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Abstract
The intestinal microbiota plays important roles in human health. This last decade, the viral fraction of the intestinal microbiota, composed essentially of phages that infect bacteria, received increasing attention. Numerous novel phage families have been discovered in parallel with the development of viral metagenomics. However, since the discovery of intestinal phages by d'Hérelle in 1917, our understanding of the impact of phages on gut microbiota structure remains scarce. Changes in viral community composition have been observed in several diseases. However, whether these changes reflect a direct involvement of phages in diseases etiology or simply result from modifications in bacterial composition is currently unknown. Here we present an overview of the current knowledge in intestinal phages, their identity, lifestyles, and their possible effects on the gut microbiota. We also gather the main data on phage interactions with the immune system, with a particular emphasis on recent findings.
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Affiliation(s)
- R Sausset
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
- Myriade, 68 boulevard de Port Royal, 75005, Paris, France
| | - M A Petit
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - V Gaboriau-Routhiau
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
- Laboratory of Intestinal Immunity, INSERM UMR 1163, Institut Imagine, Paris, France
- Université Paris Descartes-Sorbonne Paris Cité, 75006, Paris, France
| | - M De Paepe
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France.
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2
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Abstract
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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Affiliation(s)
- R. Sausset
- 0000 0004 4910 6535grid.460789.4Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France ,Myriade, 68 boulevard de Port Royal, 75005 Paris, France
| | - M. A. Petit
- 0000 0004 4910 6535grid.460789.4Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - V. Gaboriau-Routhiau
- 0000 0004 4910 6535grid.460789.4Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France ,grid.462336.6Laboratory of Intestinal Immunity, INSERM UMR 1163, Institut Imagine, Paris, France ,0000 0001 2188 0914grid.10992.33Université Paris Descartes-Sorbonne Paris Cité, 75006 Paris, France
| | - M. De Paepe
- 0000 0004 4910 6535grid.460789.4Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
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Hughes JM, Petit MA. Biological underpinnings of Frost's mechanostat thresholds: the important role of osteocytes. J Musculoskelet Neuronal Interact 2010; 10:128-135. [PMID: 20516629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Harold Frost first proposed the existence of several mechanical thresholds in bone, two of which determine whether bone is added to, or lost from, the skeleton. Recent evidence from bone biology helps elucidate the role of osteocytes in determining these mechanical thresholds. Specifically, when mechanical stimuli fall below the resorption threshold, osteocyte apoptosis occurs, followed by bone resorption. Conversely, mechanical loading maintains osteocytes viability, and consequently, no bone is lost. With a greater than customary mechanical stimulus, osteocytes perturbation from pulsatile fluid flow results in release of anabolic factors and subsequent bone formation. Osteocytes also play a pivotal role in bone remodeling in response to alterations in the mechanical environment. In particular, osteocyte apoptosis results in bone turnover in disuse as well as in response to greater than customary mechanical stimuli due to microdamage accumulation. Given the important role of osteocytes in bone modeling and remodeling, these cells provide an ideal target for both drug therapies and exercise to prevent bone fragility.
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Affiliation(s)
- J M Hughes
- University of Minnesota, School of Kinesiology, Minneapolis, MN 55455, USA
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Devlin MJ, Stetter CM, Lin HM, Beck TJ, Legro RS, Petit MA, Lieberman DE, Lloyd T. Peripubertal estrogen levels and physical activity affect femur geometry in young adult women. Osteoporos Int 2010; 21:609-17. [PMID: 19575140 PMCID: PMC3230251 DOI: 10.1007/s00198-009-0999-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2009] [Accepted: 05/22/2009] [Indexed: 10/20/2022]
Abstract
UNLABELLED The growing skeleton is particularly responsive to exercise around the time of puberty, suggesting a possible role for estrogen in mechanical adaptation in young women. We assessed femoral neck strength index at age 17 in young women with varying adolescent physical activity levels and E2 levels in the first 3 years after menarche. The results indicate that both E2 levels in the first year after menarche and adolescent physical activity are positively associated with bone strength in young adulthood, such that hormone levels may modify human osteogenic responses to exercise. INTRODUCTION It is well established that physical activity contributes to bone strength in young females, but less is known about how peripubertal estrogen affects skeletal responses to exercise. METHODS We used data from 84 participants in the Penn State Young Women's Health Study to test the prediction that young women who (1) had higher E2 levels during the first year after menarche or (2) were more physically active in adolescence will have greater bone strength at the end of adolescence. Subjects were divided into tertiles of physical activity and of E2 level in the first, second, and third postmenarchal years, and femoral strength was calculated from dual-energy X-ray absorptiometry scans of the proximal femur using hip structure analysis. RESULTS At age 17, subjects with the highest E2 levels in year 1 after menarche had 5-14% greater strength in the narrow neck and intertrochanteric region, and the most active subjects had 10-11% greater strength in the femoral narrow neck vs. less active girls. CONCLUSIONS This study suggests that both physical activity and peripubertal estrogen have important influences on young adult bone strength and that hormone levels may be mediators of human osteogenic responses to exercise.
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Affiliation(s)
- M J Devlin
- Department of Anthropology, Harvard University, Cambridge, MA 02138, USA.
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Wetzsteon RJ, Hughes JM, Kaufman BC, Vazquez G, Stoffregen TA, Stovitz SD, Petit MA. Ethnic differences in bone geometry and strength are apparent in childhood. Bone 2009; 44:970-5. [PMID: 19442622 DOI: 10.1016/j.bone.2009.01.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Revised: 12/31/2008] [Accepted: 01/09/2009] [Indexed: 11/28/2022]
Abstract
PURPOSE Ethnic differences in bone strength and structure likely contribute to the disparity in fracture rates, however few studies have assessed bone structure in multiethnic cohorts of children. The purpose of this study was to investigate ethnic differences in bone strength in childhood and to characterize the structural bases for these differences. METHODS Peripheral quantitative computed tomography (pQCT 3000, Orthometrix) was used to assess bone parameters at the radius and tibia in Caucasian (CA, n=21), African American (AA, n=23), and Hispanic (HI, n=29) children (10.9+/-0.1 yrs). At the distal site (8%), we measured compressive bone strength (BSI), trabecular and total bone density, and total bone area. Polar strength-strain index, total and cortical bone area, and cortical density were assessed at the midshaft (50%). Muscle cross-sectional area (CSA) and fat CSA were measured at the tibia (66%) and the radius (50%). Physical activity and calcium intake were assessed by questionnaire. Analysis of covariance was used to compare bone outcomes among ethnic groups adjusting for age, sex, limb length and muscle CSA. RESULTS Age, BMI, and body composition were similar among the 3 groups, however AA children were taller and had longer bone length. At all sites, AA and HI children had higher bone strength (SSIp and BSI +10-37%) than CA children due mainly to greater bone tissue density (2-18%>CA) at the distal sites of the radius and tibia. The greater bone strength at the midshaft was due to both a higher bone density (2-5%) and greater bone area than CA (7-18%). CONCLUSION AA and HI children have significantly higher bone strength than CA children, due to greater bone volumetric density and greater cortical area. AA and HI children also have higher bone strength relative to load. These observations suggest that ethnic differences in bone strength manifest in childhood.
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Affiliation(s)
- R J Wetzsteon
- Department of Pediatrics, Division of Nephrology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
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Macdonald HM, Kontulainen SA, Petit MA, Beck TJ, Khan KM, McKay HA. Does a novel school-based physical activity model benefit femoral neck bone strength in pre- and early pubertal children? Osteoporos Int 2008; 19:1445-56. [PMID: 18357403 DOI: 10.1007/s00198-008-0589-z] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Accepted: 01/30/2008] [Indexed: 11/28/2022]
Abstract
UNLABELLED The effects of physical activity on bone strength acquisition during growth are not well understood. In our cluster randomized trial, we found that participation in a novel school-based physical activity program enhanced bone strength acquisition and bone mass accrual by 2-5% at the femoral neck in girls; however, these benefits depended on teacher compliance with intervention delivery. Our intervention also enhanced bone mass accrual by 2-4% at the lumbar spine and total body in boys. INTRODUCTION We investigated the effects of a novel school-based physical activity program on femoral neck (FN) bone strength and mass in children aged 9-11 yrs. METHODS We used hip structure analysis to compare 16-month changes in FN bone strength, geometry and bone mineral content (BMC) between 293 children who participated in Action Schools! BC (AS! BC) and 117 controls. We assessed proximal femur (PF), lumbar spine (LS) and total body (TB) BMC using DXA. We compared change in bone outcomes between groups using linear regression accounting for the random school effect and select covariates. RESULTS Change in FN strength (section modulus, Z), cross-sectional area (CSA), subperiosteal width and BMC was similar between control and intervention boys, but intervention boys had greater gains in BMC at the LS (+2.7%, p = 0.05) and TB (+1.7%, p = 0.03) than controls. For girls, change in FN-Z tended to be greater (+3.5%, p = 0.1) for intervention girls than controls. The difference in change increased to 5.4% (p = 0.05) in a per-protocol analysis that included girls whose teachers reported 80% compliance. CONCLUSION AS! BC benefits bone strength and mass in school-aged children; however, our findings highlight the importance of accounting for teacher compliance in classroom-based physical activity interventions.
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Affiliation(s)
- H M Macdonald
- Department of Orthopaedics, University of British Columbia, #302 2647 Willow St, Vancouver, BC, Canada, V5Z 3P1
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7
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DiVasta AD, Beck TJ, Petit MA, Feldman HA, LeBoff MS, Gordon CM. Bone cross-sectional geometry in adolescents and young women with anorexia nervosa: a hip structural analysis study. Osteoporos Int 2007; 18:797-804. [PMID: 17205221 PMCID: PMC3195422 DOI: 10.1007/s00198-006-0308-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2006] [Accepted: 11/22/2006] [Indexed: 01/23/2023]
Abstract
INTRODUCTION Better characterization of bone geometry in adolescents with anorexia nervosa (AN) may improve understanding of skeletal deficits in this population. Our objective was to determine whether hip cross-sectional geometry and bone strength were altered in adolescents with AN. METHODS Measurements of the left total proximal femur and body composition were obtained in 85 adolescents with AN and 61 healthy controls by dual X-ray absorptiometry. The Hip Structural Analysis (HSA) program was used to determine aBMD, cross-sectional area (CSA), and section modulus (Z) at the femoral neck and shaft. Strength indices were calculated and corrected for lean mass. RESULTS Femoral neck and shaft aBMD were lower in AN patients than healthy controls (-36% and -29%, p < 0.001). In both regions, bone CSA and Z were lower in AN sufferers (-11 to -35%, p < 0.001). While lean body mass correlated with HSA variables (r = 0.48 to 0.58, p < 0.001), body fat did not. AN sufferers had lower indices of both whole bone strength (-40%, p < 0.001) and relative bone strength (-36%, p < 0.001) than controls. CONCLUSIONS Anorexia nervosa sufferers had decreased resistance to axial (CSA) and bending loads (Z) compared with healthy controls. Differences in strength properties were significant even when adjusted for lean mass, suggesting that not only decreased mechanical loading, but also known metabolic differences are likely responsible for deficits in bone strength in these patients.
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Affiliation(s)
- A D DiVasta
- Division of Adolescent Medicine, Children's Hospital Boston, Boston, MA 02115, USA.
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Petit MA, Beck TJ, Kontulainen SA. Examining the developing bone: What do we measure and how do we do it? J Musculoskelet Neuronal Interact 2005; 5:213-24. [PMID: 16172512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The clinical tools available to evaluate bone development in children are often ambiguous, and difficult to interpret. Unfortunately bone densitometry methods (i.e., dual energy X-ray absorptiometry, DXA) which have a relatively straightforward application in adult osteoporosis, are far more difficult to evaluate in the growing skeleton. Even with adequate "adjustment" for bone size or maturity, bone "density" (areal or volumetric) alone often gives an inaccurate assessment of bone strength--especially in children. Ideally, we would like to measure both material and geometric properties of bone to accurately estimate "strength". Mechanically meaningful measures of bone geometry (bone cross-sectional area, cortical thickness) and estimates of bending strength (section modulus, or SSI) are available with non-invasive techniques such as (p)QCT and some DXA software. With new technology it might be possible to also measure bone material properties, which will be especially important in some pediatric disorders. In children, we also need to know something about the loads imposed on a child's bone and consider not only absolute bone strength, but also the strength of bone relative to the physiologic loads. Interpreting bone strength in light of the loads imposed (particularly muscle force) is critical for an accurate diagnosis of the developing bone.
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Affiliation(s)
- M A Petit
- University of Minnesota, School of Kinesiology, Minneapolis, MN 55455, USA.
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Whipple TJ, Le BH, Demers LM, Chinchilli VM, Petit MA, Sharkey N, Williams NI. Acute Effects of Moderate Intensity Resistance Exercise on Bone Cell Activity. Int J Sports Med 2004; 25:496-501. [PMID: 15459829 DOI: 10.1055/s-2004-820942] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Resistance exercise has positive effects on bone mass, but little is known about the mechanisms by which this occurs. The purpose of this study was to determine if a single bout of moderate intensity resistance exercise alters biochemical markers of bone cell activity. Indices of bone turnover were measured in nine healthy, untrained men (21.9 +/- 1.2 yrs old), before and following a single 45 minute session of resistance exercise, and during a control trial. A cross-over design was used so that all participants performed both trials in random order. Blood samples were collected immediately before, immediately after, and at 1, 8, 24, and 48 hours post exercise and analyzed for bone-specific alkaline phosphatase (BAP), type I collagen propeptide (PICP), and type I collagen N-telopeptide (sNTX). Urine from the second morning void was collected over four days (day before, day of, and two days following exercise) and analyzed for type I collagen N-telopeptide (uNTX). Exercise resulted in a significant increase (p < 0.05) in the ratio of biochemical markers of bone formation to bone resorption eight hours post exercise, largely due to a decrease in sNTX. Markers return to baseline within 24 hrs. These data suggest that moderate intensity resistance training acutely reduces bone resorption, leading to a favorable change in overall bone turnover, for at least 8 hours post exercise in untrained young men. Further work is needed to determine if long-term benefits to bone strength follow with persistent training.
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Affiliation(s)
- T J Whipple
- Department of Kinesiology and Noll Laboratory, Pennsylvania State University, Hershey, PA, USA
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Lebrun CM, Petit MA, McKenzie DC, Taunton JE, Prior JC. Decreased maximal aerobic capacity with use of a triphasic oral contraceptive in highly active women: a randomised controlled trial. Br J Sports Med 2003; 37:315-20. [PMID: 12893716 PMCID: PMC1724664 DOI: 10.1136/bjsm.37.4.315] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Oral contraceptives are commonly used by women athletes. However, their effect on athletic performance is unclear. OBJECTIVES To examine the effects of a moderate dose, triphasic oral contraceptive on measures of athletic performance in highly trained women athletes. METHODS This is a double blind, placebo controlled trial in 14 women with ovulatory menstrual cycles and maximal aerobic capacity (VO(2)MAX) >/==" BORDER="0">50 ml/kg/min. Four measures of athletic performance were tested: VO(2)MAX, anaerobic capacity (anaerobic speed test), aerobic endurance (time to fatigue at 90% of VO(2)MAX), and isokinetic strength (Cybex II dynamometer). Height, weight, and six skinfold measurements were also recorded. All these observational tests were completed during both the follicular and mid-luteal phases of an ovulatory menstrual cycle. Cycle phases were confirmed by assaying plasma oestradiol and progesterone. Participants were subsequently randomly assigned to either a tricyclic oral contraceptive or placebo and retested in identical fashion (oral contraceptive phase). RESULTS Absolute and relative changes in VO(2)MAX from follicular to oral contraceptive phase decreased in the oral contraceptive group by 4.7%, whereas the placebo group showed a slight increase (+1.5%) over the same time period. Two of the women taking oral contraceptive had decreases of 4 and 9 ml/kg/min. In contrast, most women in the placebo group improved or maintained VO(2)MAX. There was also a significant increase in the sum of skinfolds in women taking oral contraceptive compared with those taking placebo (p<0.01). There were no significant changes in other physiological variables (maximum ventilation, heart rate, respiratory exchange ratio, packed cell volume) or measures of performance (anaerobic speed test, aerobic endurance, isokinetic strength) as a function of oral contraceptive treatment. CONCLUSIONS The decrease in VO(2)MAX that occurs when oral contraceptive is taken may influence elite sporting performance in some women. Further studies are required to determine the mechanisms of this change.
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Affiliation(s)
- C M Lebrun
- Fowler Kennedy Sport Medicine Clinic 3M Centre, University of Western Ontario, London, ON N6A 3K7, Canada.
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MacKelvie KJ, McKay HA, Petit MA, Moran O, Khan KM. Bone mineral response to a 7-month randomized controlled, school-based jumping intervention in 121 prepubertal boys: associations with ethnicity and body mass index. J Bone Miner Res 2002; 17:834-44. [PMID: 12009014 DOI: 10.1359/jbmr.2002.17.5.834] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We examined the effects of a 7-month jumping intervention (10 minutes, 3 times per week) on bone mineral gain in prepubertal Asian and white boys (10.3+/-0.6 years, 36.0+/-9.2 kg) at 14 schools randomized to control (n = 60) and intervention (n = 61) groups. Intervention and control groups had similar mean baseline and change in height, weight, lean mass and fat mass, baseline areal bone mineral density (aBMD; g/cm2), bone mineral content (BMC; g; dual-energy X-ray absorptiometry [DXA], QDR 4500W), and similar average physical activity and calcium intakes. Over 7 months, the intervention group gained more total body (TB) BMC (1.6%,p < 0.01) and proximal femur (PF) aBMD (1%, p < 0.05) than the control group after adjusting for age, baseline weight, change in height, and loaded physical activity. We also investigated the 41 Asian and 50 white boys (10.2+/-0.6 years and 31.9+/-4.4 kg) who were below the 75th percentile (19.4 kg/m2) of the cohort mean for baseline body mass index (BMI). Boys in the intervention group gained significantly more TB and lumbar spine (LS) BMC, PF aBMD, and trochanteric (TR) aBMD (+ approximately2%) than boys in the control group (adjusted for baseline weight, final Tanner stage, change in height, and loaded physical activity). Bone changes were similar between Asians and whites. Finally, we compared the boys in the control group (n = 16) and the boys in the intervention group (n = 14) whose baseline BMI fell in the highest quartile (10.5+/-0.6 years and 49.1+/-8.2 kg). Seven-month bone changes (adjusted as aforementioned) were similar in the control and intervention groups. In summary, jumping exercise augmented bone mineral accrual at several regions equally in prepubertal Asian and white boys of average or low BMI, and intervention effects on bone mineral were undetectable in high BMI prepubertal boys.
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Affiliation(s)
- K J MacKelvie
- School of Human Kinetics, University of British Columbia, Vancouver, Canada
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Petit MA, McKay HA, MacKelvie KJ, Heinonen A, Khan KM, Beck TJ. A randomized school-based jumping intervention confers site and maturity-specific benefits on bone structural properties in girls: a hip structural analysis study. J Bone Miner Res 2002; 17:363-72. [PMID: 11874228 DOI: 10.1359/jbmr.2002.17.3.363] [Citation(s) in RCA: 251] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We compared 7-month changes in bone structural properties in pre- and early-pubertal girls randomized to exercise intervention (10-minute, 3 times per week, jumping program) or control groups. Girls were classified as prepubertal (PRE; Tanner breast stage 1; n = 43 for intervention [I] and n = 25 for control [C]) or early-pubertal (EARLY; Tanner stages 2 and 3; n = 43 for I and n = 63 for C). Mean +/- SD age was 10.0 +/- 0.6 and 10.5 +/- 0.6 for the PRE and EARLY groups, respectively. Proximal femur scans were analyzed using a hip structural analysis (HSA) program to assess bone mineral density (BMD), subperiosteal width, and cross-sectional area and to estimate cortical thickness, endosteal diameter, and section modulus at the femoral neck (FN), intertrochanter (IT), and femoral shaft (FS) regions. There were no differences between intervention and control groups for baseline height, weight, calcium intake, or physical activity or for change over 7 months (p > 0.05). We used analysis of covariance (ANCOVA) to examine group differences in changes of bone structure, adjusting for baseline weight, height change, Tanner breast stage, and physical activity. There were no differences in change for bone structure in the PRE girls. The more mature girls (EARLY) in the intervention group showed significantly greater gains in FN (+2.6%, p = 0.03) and IT (+1.7%, p = 0.02) BMD. Underpinning these changes were increased bone cross-sectional area and reduced endosteal expansion. Changes in subperiosteal dimensions did not differ. Structural changes improved section modulus (bending strength) at the FN (+4.0%, p = 0.04), but not at the IT region. There were no differences at the primarily cortical FS. These data provide insight into geometric changes that underpin exercise-associated gain in bone strength in early-pubertal girls.
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Affiliation(s)
- M A Petit
- School of Human Kinetics, University of British Columbia, Vancouver, Canada
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13
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Petit MA, Buffello-Le Guillou D, Roche B, Dussaix E, Duclos-Vallée JC, Féray C, Samuel D. Residual hepatitis B virus particles in liver transplant recipients receiving lamivudine: PCR quantitation of HBV DNA and ELISA of preS1 antigen. J Med Virol 2001; 65:493-504. [PMID: 11596084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
Lamivudine, an antiviral agent, has a potential role in the treatment of recurrent or acquired de novo hepatitis B virus (HBV) infection after liver transplantation. During lamivudine therapy, residual HBV particles in serum, PBMC, and liver were quantified in 7 patients in whom hepatitis B occurred de novo (n = 4) or recurred (n = 3). HBV DNA and preS1 antigen were measured using a sensitive PCR technique and an in-house ELISA method, respectively. The genetic and antigenic properties of HBV variants that emerged during lamivudine treatment were also examined. One month after the outset of lamivudine treatment, all 7 patients remained positive for both HBV DNA and preS1 antigen in serum, reflecting residual HBV replication. At the end of therapy, four patients were considered to be lamivudine responders, including one who seroconverted to anti-HBs but remained HBV DNA positive in the liver (> 10(3) copies/microg of DNA). Among the three patients who did not respond to lamivudine, one had pol mutations (L450P and S550C) that had not been described previously, in addition to the common mutations within the YMDD locus and B domain. Defective core and preS viral proteins and atypical sedimentation profiles of HBV DNA-positive particles were observed in all three lamivudine-resistant patients. These findings confirm the persistence of HBV in liver transplant recipients despite strong inhibition of replication by lamivudine, and show abnormal viral transcription and/or morphogenesis in lamivudine-resistant patients.
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Affiliation(s)
- M A Petit
- INSERM E99-41 and UPRES 1596, Centre Hépato-Biliaire, Villejuif, France.
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Carter ND, Khan KM, Petit MA, Heinonen A, Waterman C, Donaldson MG, Janssen PA, Mallinson A, Riddell L, Kruse K, Prior JC, Flicker L, McKay HA. Results of a 10 week community based strength and balance training programme to reduce fall risk factors: a randomised controlled trial in 65-75 year old women with osteoporosis. Br J Sports Med 2001; 35:348-51. [PMID: 11579072 PMCID: PMC1724401 DOI: 10.1136/bjsm.35.5.348] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVE To test the efficacy of a community based 10 week exercise intervention to reduce fall risk factors in women with osteoporosis. METHODS Static balance was measured by computerised dynamic posturography (Equitest), dynamic balance by timed figure of eight run, and knee extension strength by dynamometry. Subjects were randomised to exercise intervention (twice weekly Osteofit classes for 10 weeks) or control groups. RESULTS The outcome in 79 participants (39 exercise, 40 control) who were available for measurement 10 weeks after baseline measurement is reported. After confounding factors had been controlled for, the exercise group did not make significant gains compared with their control counterparts, although there were consistent trends toward greater improvement in all three primary outcome measures. Relative to the change in control subjects, the exercise group improved by 2.3% in static balance, 1.9% in dynamic balance, and 13.9% in knee extension strength. CONCLUSIONS A 10 week community based physical activity intervention did not significantly reduce fall risk factors in women with osteoporosis. However, trends toward improvement in key independent risk factors for falling suggest that a study with greater power may show that these variables can be improved to a level that reaches statistical significance.
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Affiliation(s)
- N D Carter
- BC Women's Hospital and Health Centre Osteoporosis Program and Faculty of Medicine, University of British Columbia, Vancouver, Canada
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Carrasco B, Fernández S, Petit MA, Alonso JC. Genetic recombination in Bacillus subtilis 168: effect of DeltahelD on DNA repair and homologous recombination. J Bacteriol 2001; 183:5772-7. [PMID: 11544244 PMCID: PMC95473 DOI: 10.1128/jb.183.19.5772-5777.2001] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2001] [Accepted: 07/09/2001] [Indexed: 11/20/2022] Open
Abstract
The B. subtilis DeltahelD allele rendered cells proficient in transformational recombination and moderately sensitive to methyl methanesulfonate when present in an otherwise Rec(+) strain. The DeltahelD allele was introduced into rec-deficient strains representative of the alpha (recF strain), beta (addA addB), gamma (recH), epsilon (DeltarecU), and zeta (DeltarecS) epistatic groups. The DeltahelD mutation increased the sensitivity to DNA-damaging agents of addAB, DeltarecU, and DeltarecS cells, did not affect the survival of recH cells, and decreased the sensitivity of recF cells. DeltahelD also partially suppressed the DNA repair phenotype of other mutations classified within the alpha epistatic group, namely the recL, DeltarecO, and recR mutations. The DeltahelD allele marginally reduced plasmid transformation (three- to sevenfold) of mutations classified within the alpha, beta, and gamma epistatic groups. Altogether, these data indicate that the loss of helicase IV might stabilize recombination repair intermediates formed in the absence of recFLOR and render recFLOR, addAB, and recH cells impaired in plasmid transformation.
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Affiliation(s)
- B Carrasco
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CSIC, Campus Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
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16
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Barr SI, Petit MA, Vigna YM, Prior JC. Eating attitudes and habitual calcium intake in peripubertal girls are associated with initial bone mineral content and its change over 2 years. J Bone Miner Res 2001; 16:940-7. [PMID: 11341340 DOI: 10.1359/jbmr.2001.16.5.940] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This 2-year prospective study examined associations among bone mineral acquisition and physical, maturational, and lifestyle variables during the pubertal transition in healthy girls. Forty-five girls, initially 10.5+/-0.6 years, participated. Body composition and bone mineral content (BMC) at the spine and total body (TB) were assessed at baseline and annually thereafter using dual-energy X-ray absorptiometry (DXA). Nutrient intakes were assessed using 3-day diet records and a calcium food frequency questionnaire (FFQ), physical activity by questionnaire, sexual maturation using Tanner's stages of breast and pubic hair maturation, growth by height and weight, and eating attitudes using the children's Eating Attitudes Test (Children's EAT). Mean children's EAT subscale scores (dieting, oral control [OC], and bulimia) were stable over time. Median split of OC subscale scores was used to form high and low OC groups. Groups had similar body composition, dietary intake, activity, and Tanner stage at baseline and 2 years. Using height, weight, and Tanner breast stage as covariates, girls with low OC scores had greater TB BMC at baseline (1452+/-221 g vs. 1387+/-197 g; p = 0.030) and 2 years (2003+/-323 g vs. 1909+/-299 g; p = 0.049) and greater lumbar spine (LS) BMC at 2 years (45.2+/-8.8 g vs. 41.2+/-9.6 g; p = 0.042). In multiple regression analysis, OC score predicted baseline, 2 years, and 2-year change in TB and spinal BMC, contributing 0.9-7.6% to explained variance. Calcium intake predicted baseline, 2 years, and 2-year change in TB BMC, explaining 1.6-5.3% of variance. We conclude that both OC and habitual calcium intake may influence bone mineral acquisition.
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Affiliation(s)
- S I Barr
- Food, Nutrition and Health, University of British Columbia, Vancouver, Canada
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17
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Delpuech O, Buffello-Le Guillou DB, Rubinstein E, Féray C, Petit MA. The hepatitis C virus (HCV) induces a long-term increase in interleukin-10 production by human CD4+ T cells (H9). Eur Cytokine Netw 2001; 12:69-77. [PMID: 11282549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Patients with chronic hepatitis C present an imbalance of Th1/Th2 cytokine production. Therefore, we investigated whether the exposure of the CD4+ T cell line H9 to HCV could induce activation of cells through synthesis of IL-10. Three infection protocols were performed to enhance HCV propagation. Viral particles were prepared by ultracentrifugation of serum from patients. From 3 to 81 days post-infection (p.i.), HCV-RNA was monitored both in supernatants and cells by nested RT-PCR, IL-10 protein in medium by ELISA, and IL-10 mRNA in cells by semi-quantitative RT-PCR. The expression of tetraspanins was analyzed by flow cytometry. The PKC signal pathway was studied using specific inhibitors. The H9 cells express CD81. HCV-RNA (+) was detected in cells until 21 days p.i, and in culture media over 39 days p.i. Up to day 81 p.i., HCV exposure induced a specific, 2-fold increase of IL-10 production by H9 cells. IL-10 production was inhibited by a PKC inhibitor (Calphostin C). This study shows that even if the infection of H9 T cells did not result in any viral progeny, HCV induced the activation of IL-10 secretion, which supports the role of IL-10 in HCV pathogenesis.
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Affiliation(s)
- O Delpuech
- INSERM E. 99-41, Centre Hépato-Biliaire, Hôpital Paul-Brousse, 12, avenue Paul-Vaillant Couturier, 94800 Villejuif, France
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18
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Abstract
DNA ligases are grouped into two families, ATP-dependent and NAD-dependent, according to the cofactor required for their activity. A surprising capability of both kinds of ligases to complement for one another in vivo has been observed. Bacillus subtilis harbours one NAD-dependent ligase, YerG, and two ATP-dependent ligases, YkoU and YoqV, this last one being encoded by the 134 kb lysogenic bacteriophage SPss and consisting of a single adenylation domain typical of ATP-dependent ligases. Because the genetics of ligases in B.subtilis had not been studied previously, the genes encoding for one ligase of each kind, yerG and yoqV, were investigated. We found that the yerG gene was essential in B.subtilis. This suggests that none of the ATP-dependent ligases was able to complement the yerG defect. In addition, the ATP-dependent ligase encoded by yoqV, when cloned on a plasmid under appropriate expression signals, was unable to rescue a yerG mutant strain. The two B.subtilis ligase genes yerG and yoqV were also introduced in an Escherichia coli strain encoding a thermosensitive ligase (ligts), and whereas yoqV did not complement the ligts defects, yerG fully complemented the growth and UV sensitivity defects of the lig mutant. We propose to rename the yerG and yoqV genes of B.subtilis ligA and ligB respectively.
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Affiliation(s)
- M A Petit
- Laboratoire de Génétique Microbienne, INRA, 78352 Jouy en Josas, France.
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19
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Le Guillou DB, Duclos-Vallée JC, Eberle F, Capel F, Petit MA. Evaluation of an enzyme-linked immunosorbent assay for detection and quantification of hepatitis B virus PreS1 envelope antigen in serum samples: comparison with two commercial assays for monitoring hepatitis B virus DNA. J Viral Hepat 2000; 7:387-92. [PMID: 10971828 DOI: 10.1046/j.1365-2893.2000.00248.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
An in-house sensitive and easy-to-use solid-phase enzyme-linked immunoassay (ELISA) was adapted for the detection and quantification of hepatitis B virus (HBV) PreS1 envelope antigen in serum, and compared with the HBV DNA Hybrid Capturetrade mark system from Murex and the polymerase chain reaction (PCR) Amplicortrade mark HBV Monitor assay from Roche. Twenty-five patients with chronic hepatitis B after liver transplantation were included in this study. The sensitivity of our ELISA was found to be 50 pg of HBsAg/PreS1Ag ml-1. The linearity was between 0.1 and 100 ng ml-1. Intra-assay reproducibility was obtained with a standard deviation of <1%. No correlation between the presence of serum PreS1 antigen and viral DNA detected by direct hybridization (Murex) was observed. In contrast, there was a significant 96% correspondence in the presence of PreS1 antigen and viral DNA detected and quantified by the PCR assay (Roche). In conclusion, the most important and reliable markers for monitoring residual HBV replication in serum were HBV DNA by the PCR assay, and virus envelope PreS1Ag by our in-house ELISA. Thus, PreS1Ag disappearance in serum could be used for evaluating the efficacy of antiviral therapies.
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Affiliation(s)
- D B Le Guillou
- Centre Hépato-Biliaire, INSERM E99-41 and UPRES 1596, Hòpital Paul Brousse, Villejuif, France; Roche Diagnostics, Grenoble, France
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20
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McKay HA, Petit MA, Bailey DA, Wallace WM, Schutz RW, Khan KM. Analysis of proximal femur DXA scans in growing children: comparisons of different protocols for cross-sectional 8-month and 7-year longitudinal data. J Bone Miner Res 2000; 15:1181-8. [PMID: 10841187 DOI: 10.1359/jbmr.2000.15.6.1181] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Dual-energy X-ray absorptiometry (DXA) is a widely used method for measuring bone mineral in the growing skeleton. Because scan analysis in children offers a number of challenges, we compared DXA results using six analysis methods at the total proximal femur (PF) and five methods at the femoral neck (FN). In total we assessed 50 scans (25 boys, 25 girls) from two separate studies for cross-sectional differences in bone area, bone mineral content (BMC), and areal bone mineral density (aBMD) and for percentage change over the short term (8 months) and long term (7 years). At the proximal femur for the short-term longitudinal analysis, there was an approximate 3.5% greater change in bone area and BMC when the global region of interest (ROI) was allowed to increase in size between years as compared with when the global ROI was held constant. Trend analysis showed a significant (p < 0.05) difference between scan analysis methods for bone area and BMC across 7 years. At the femoral neck, cross-sectional analysis using a narrower (from default) ROI, without change in location, resulted in a 12.9 and 12.6% smaller bone area and BMC, respectively (both p < 0.001). Changes in FN area and BMC over 8 months were significantly greater (2.3%, p < 0.05) using a narrower FN rather than the default ROI. Similarly, the 7-year longitudinal data revealed that differences between scan analysis methods were greatest when the narrower FN ROI was maintained across all years (p < 0.001). For aBMD there were no significant differences in group means between analysis methods at either the PF or FN. Our findings show the need to standardize the analysis of proximal femur DXA scans in growing children.
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Affiliation(s)
- H A McKay
- School of Human Kinetics, University of British Columbia, Vancouver, Canada
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21
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McKay HA, Petit MA, Khan KM, Schutz RW. Lifestyle determinants of bone mineral: a comparison between prepubertal Asian- and Caucasian-Canadian boys and girls. Calcif Tissue Int 2000; 66:320-4. [PMID: 10773099 DOI: 10.1007/s002230010067] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The purpose of this study was to examine the difference in lifestyle and morphometric factors that affect bone mineral and the attainment of peak bone mass in 168 healthy Asian (n = 58) and Caucasian (n = 110) Canadian, prepubertal girls and boys (mean age 8.9+/-0.7) living in close geographical proximity. DXA (Hologic 4500) scans of the proximal femur (with regions), lumbar spine, and total body (TB) were acquired. We report areal bone mineral densities (aBMD g/cm(2)) at all sites and estimated volumetric density (aBMD, g/cm(3)) at the femoral neck. Dietary calcium, physical activity, and maturity were estimated by questionnaire. Of these prepubertal children, all of the boys and 89% of the girls were Tanner stage 1. A 2x2 ANOVA demonstrated no difference between ethnicities for height, weight, body fat, or bone mineral free lean mass. Asian children consumed significantly less dietary calcium (35%) on average and were significantly less active (15%) than their Caucasian counterparts (P<0.001). There were significant ethnicity main effects for femoral neck bone mineral content (BMC) and alphaBMD (both P<0.001) and significant sex by ethnicity interactions (P<0.01). The Asian boys had significantly lower femoral neck BMC (11%), aBMD (8%), and vBMD (4.4%). At the femoral neck, BMFL mass, sex, and physical activity explained 37% of the total variance in aBMD (P<0.05). In summary, this study demonstrated differences in modifiable lifestyle factors and femoral neck bone mineral between Asian and Caucasian boys.
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Affiliation(s)
- H A McKay
- School of Human Kinetics, University of British Columbia, Vancouver, B.C. V6J 1K7, Canada
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22
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Pichoud C, Berby F, Stuyver L, Petit MA, Trépo C, Zoulim F. Persistence of viral replication after anti-HBe seroconversion during antiviral therapy for chronic hepatitis B. J Hepatol 2000; 32:307-16. [PMID: 10707872 DOI: 10.1016/s0168-8278(00)80077-x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
BACKGROUND/AIMS Hepatitis B virus genome mutants may be selected during the immune-mediated clearance of infection or during long-term nucleoside analog administration and may escape both antiviral pressures. The pattern of anti-HBe seroconversion was analyzed in patients receiving new nucleoside analogs, lamivudine or famciclovir, in comparison with patients treated with interferon alpha. METHODS Eighteen consecutive patients who seroconverted to anti-HBe were included in the study. Serial serum samples were studied with the quantitative determination of HBV DNA by the branched DNA assay (Chiron) and by a quantitative PCR assay (Roche diagnostics), determination of pre-S1 Ag, the genetic analysis of the viral genome with the determination of pre-core promoter or pre-core region mutations with a line probe assay (Innogenetics) and, in selected samples of polymerase gene mutations. RESULTS The quantitative PCR assay was found to be more sensitive than the bDNA assay, allowing a 25-log decrease in viral DNA levels to be demonstrated after anti-HBe seroconversion. Viral persistence after anti-HBe seroconversion induced by interferon, lamivudine or famciclovir, was often associated with circulating HBV genomes harboring mutations in the precore promoter. The clinical significance of these findings was demonstrated by the observation of reversion to HBeAg in two patients treated with interferon and one with lamivudine. CONCLUSION Persistence of significant levels of viremia that are not detected by the branched DNA assay may be observed after anti-HBe seroconversion. A precise monitoring of viremia levels with more sensitive assays and HBV mutant strains is warranted in patients undergoing antiviral therapy.
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Affiliation(s)
- C Pichoud
- INSERM Unit 271, Hôtel Dieu, Lyon, France
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23
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McKay HA, Petit MA, Schutz RW, Prior JC, Barr SI, Khan KM. Augmented trochanteric bone mineral density after modified physical education classes: a randomized school-based exercise intervention study in prepubescent and early pubescent children. J Pediatr 2000; 136:156-62. [PMID: 10657819 DOI: 10.1016/s0022-3476(00)70095-3] [Citation(s) in RCA: 191] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
BACKGROUND Of the few exercise intervention studies focusing on pediatric populations, none have confined the intervention to the scheduled physical education curriculum. OBJECTIVE To examine the effect of an 8-month school-based jumping program on the change in areal bone mineral density (aBMD), in grams per square centimeter, of healthy third- and fourth-grade children. STUDY DESIGN Ten elementary schools were randomized to exercise (n = 63) and control groups (n = 81). Exercise groups did 10 tuck jumps 3 times weekly and incorporated jumping, hopping, and skipping into twice weekly physical education classes. Control groups did regular physical education classes. At baseline and after 8 months of intervention, we measured aBMD and lean and fat mass by dual-energy x-ray absorptiometry (Hologic QDR-4500). Calcium intake, physical activity, and maturity were estimated by questionnaire. RESULTS The exercise group showed significantly greater change in femoral trochanteric aBMD (4.4% vs 3.2%; P <.05). There were no group differences at other sites. Results were similar after controlling for covariates (baseline aBMD change in height, change in lean, calcium, physical activity, sex, and ethnicity) in hierarchical regression. CONCLUSIONS An easily implemented school-based jumping intervention augments aBMD at the trochanteric region in the prepubertal and early pubertal skeleton.
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Affiliation(s)
- H A McKay
- Departments of Human Kinetics, Medicine, Division of Endocrinology and Metabolism, and Human Nutrition, University of British Columbia, Vancouver, British Columbia, Canada
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24
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Roque Afonso AM, Jiang J, Penin F, Tareau C, Samuel D, Petit MA, Bismuth H, Dussaix E, Féray C. Nonrandom distribution of hepatitis C virus quasispecies in plasma and peripheral blood mononuclear cell subsets. J Virol 1999; 73:9213-21. [PMID: 10516029 PMCID: PMC112955 DOI: 10.1128/jvi.73.11.9213-9221.1999] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The existence of an extrahepatic reservoir of hepatitis C virus (HCV) is suggested by differences in quasispecies composition between the liver, peripheral blood mononuclear cells, and serum. We studied HCV RNA compartmentalization in the plasma of nine patients, in CD19(+), CD8(+), and CD4(+) positively selected cells, and also in the negatively selected cell fraction (NF). HCV RNA was detected in all plasma samples, in seven of nine CD19(+), three of eight CD8(+), and one of nine CD4(+) cell samples, and in seven of eight NF cells. Cloning and sequencing of HVR1 in two patients showed a sequence grouping: quasispecies from a given compartment (all studied compartments for one patient and CD8(+) and NF for the other) were statistically more genetically like each other than like quasispecies from any other compartment. The characteristics of amino acid and nucleotide substitutions suggested the same structural constraints on HVR1, even in very divergent strains from the cellular compartments, and homogeneous selection pressure on the different compartments. These findings demonstrate the compartmental distribution of HCV quasispecies within peripheral blood cell subsets and have important implications for the study of extrahepatic HCV replication and interaction with the immune system.
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Affiliation(s)
- A M Roque Afonso
- Centre Hépato-Biliaire, Laboratoire de Recherche, Equipe Mixte INSERM (Institut National de la Santé et de la Recherche Médicale) 9941, 94804 Villejuif, France
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25
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Abstract
PURPOSE Exercise is understood to exert positive effects on bone. However cancellous bone has not been shown to increase with exercise. Previous results of our 1-yr observational prospective study in ovulatory women related 20% of the change in cancellous spinal bone mineral density (BMD), measured by quantitative computed tomography (QCT), to luteal phase length (the time from ovulation to menstruation, LL). METHODS The 66 women who documented exercise daily included normally active women (N = 23) and those who ran consistently or were increasing running in preparation for a marathon (N = 43). Exercise did not affect BMD change in the women as a whole. We re-evaluated those data to determine whether exercise-related effects on spinal cancellous BMD change in regularly cycling premenopausal women were related to ovulatory characteristics. The potential relationship of exercise to BMD change was reanalyzed by stratifying women into tertiles according to average LL documented by quantitative basal temperature analysis. RESULTS Repeated-measures ANOVA indicated independent positive effects of both luteal length (P = 0.001) and activity (P = 0.041). The 11 runners with LL > 10.9 d had a nonsignificant 0.5% increase in lumbar BMD while the 15 who averaged short LL (<9.9 d) experienced a significant 3.6% loss. In the runners as a group, however, kilometers run per week was negatively related to BMD change throughout (r = -0.347, P = 0.024). CONCLUSIONS These data are the first to indicate that, in women with regular cycles, luteal length and exercise independently and positively affect change in spinal cancellous BMD.
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Affiliation(s)
- M A Petit
- Department of Human Kinetics, University of British Columbia and Vancouver Hospital Health Sciences Center, Canada
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26
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Petit MA, Hitchcock CL, Prior JC, Barr SI, Vigna YM, McKay HA, Khan KM. Ovulation and spinal bone mineral density. J Clin Endocrinol Metab 1998; 83:3757-60. [PMID: 9768701 DOI: 10.1210/jcem.83.10.5187-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Duclos-Vallée JC, Capel F, Mabit H, Petit MA. Phosphorylation of the hepatitis B virus core protein by glyceraldehyde-3-phosphate dehydrogenase protein kinase activity. J Gen Virol 1998; 79 ( Pt 7):1665-70. [PMID: 9680129 DOI: 10.1099/0022-1317-79-7-1665] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In order to characterize the hepatitis B virus (HBV) hepatocellular receptor, several proteins have previously been identified in HepG2 hepatoma cells and in primary cultured normal human hepatocytes (PCHs) that reacted with an anti-idiotypic antibody against a preS1(21-47)-specific MAb (F35.25). Here, we report the identification of one of these preS1-binding proteins, a 35 kDa protein (preS1-BP35), as glyceraldehyde-3-phosphate dehydrogenase (GAPD). GAPD is well-known as a key enzyme involved in glycolysis and gluconeogenesis. Nevertheless, GAPD has also been shown to have many other functions such as protein kinase activity (GAPD-PK). HBV core particles derived from infected hepatocytes possess an associated kinase activity that phosphorylates HBcAg, and the nucleocapsid may acquire sequential functions through selective phosphorylation. Therefore, we have investigated the potential role of GAPD-PK in HBV replication. In this study, we found that the endogenous PK associated with human liver-derived HBV core particles (hL-HBcAg) and GAPD-PK were sensitive to the same types of inhibitors. Interestingly, capsid protein phosphorylation decreased in a concentration-dependent manner (at concentrations of 5-30 mM) in the presence of specific inhibitors for GAPD-PK (NADH and GAP). Furthermore, we demonstrated in vitro that GAPD-PK could phosphorylate the major core protein P22 in hL-HBcAg particles. The data suggest that GAPD is an additional cellular kinase which might interfere in the life-cycle of HBV.
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Petit MA, Dervyn E, Rose M, Entian KD, McGovern S, Ehrlich SD, Bruand C. PcrA is an essential DNA helicase of Bacillus subtilis fulfilling functions both in repair and rolling-circle replication. Mol Microbiol 1998; 29:261-73. [PMID: 9701819 DOI: 10.1046/j.1365-2958.1998.00927.x] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The only DNA helicase essential for Escherichia coli viability is DnaB, the chromosome replication for helicase. In contrast, in Bacillus subtilis, in addition to the DnaB counterpart called DnaC, we have found a second essential DNA helicase, called PcrA. It is 40% identical to the Rep and UvrD DNA helicases of E. coli and 61% identical to the PcrA helicase of Staphylococcus aureus. This gene is located at 55 degree on the chromosome and belongs to a putative operon together with a ligase gene (lig) and two unknown genes named pcrB and yerH. As PcrA was essential for cell viability, conditional mutants were constructed. In such mutants, chromosomal DNA synthesis was slightly decreased upon PcrA depletion, and rolling-circle replication of the plasmid pT181 was inhibited. Analysis of the replication intermediates showed that leading-strand synthesis of pT181 was prevented upon PcrA depletion. To compare PcrA with Rep and UvrD directly, the protein was produced in rep and uvrD mutants of E. coli. PcrA suppressed the UV sensitivity defect at a uvrD mutant but not its mutator phenotype. Furthermore, it conferred a Rep-phenotype on E. coli. Altogether, these results show that PcrA is an helicase used for plasmid rolling-circle replication and suggest that it is also involved in UV repair.
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Affiliation(s)
- M A Petit
- Laboratoire de Génétique Microbienne, INRA, Jouy en Josas, France.
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29
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Petit MA, Nelson CM, Rhodes EC. Comparison of a mathematical model to predict 10-km performance from the Conconi test and ventilatory threshold measurements. Can J Appl Physiol 1997; 22:562-72. [PMID: 9415829 DOI: 10.1139/h97-036] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The purpose of this study was to validate a mathematical model (MM) that evaluates the Conconi test and predicts 10-km race time. In addition, the relationship between ventilatory threshold (Tvent) determined from a laboratory test and heart rate deflection (HRd) from the Conconi test were examined. Seventeen trained runners performed the Conconi test, and performance times were predicted using a MM based on a logistics function. A correlational analysis indicated a highly significant relationship (r = .98, p < .01) between MM predicted time and actual time. Significant relationships were found between velocity at Tvent and HRd (r = .95, p < .01), and predicted times from each method (r = .96, p < .01). Heart rates from Tvent and HRd were also related (r = .79, p < .01). These results suggest that a MM of the Conconi test is a valid method of predicting 10-km performance and is closely related to traditional laboratory measures.
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Affiliation(s)
- M A Petit
- School of Human Kinetics, University of British Columbia, Vancouver
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30
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Leroux-Roels G, Desombere I, De Tollenaere G, Petit MA, Desmons P, Hauser P, Delem A, De Grave D, Safary A. Hepatitis B vaccine containing surface antigen and selected preS1 and preS2 sequences. 1. Safety and immunogenicity in young, healthy adults. Vaccine 1997; 15:1724-31. [PMID: 9364674 DOI: 10.1016/s0264-410x(97)00117-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The safety and immunogenicity of a yeast-derived recombinant hepatitis B virus (HBV) vaccine containing surface antigen (S) and selected preS1 and preS2 sequences (S-L*) were compared with those of a vaccine prepared with S alone (Engerix-B). S-L* consisted of composite particles containing S and L* at a ratio of 70/30. L* encompassed amino acid residues 12-52 of preS1 residues 133-145 of preS2, and the entire S domain. A total of 100 healthy, HBV-seronegative, young adults were randomized to receive 20 micrograms/dose of either S-L* or Engerix-B under double-blind conditions according to a 0-, 1-, 2-, 12-month schedule. In vivo humoral and in vitro lymphoproliferative responses to S and preS regions were monitored. Addition of the selected preS sequences to S did not enhance the in vivo humoral anti-HBs response but improved the in vitro stimulating capacity of the antigen (L*) in S-L* primed subjects.
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Affiliation(s)
- G Leroux-Roels
- Department of Clinical Chemistry, University of Gent, Belgium.
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Leroux-Roels G, Desombere I, Cobbaut L, Petit MA, Desmons P, Hauser P, Delem A, De Grave D, Safary A. Hepatitis B vaccine containing surface antigen and selected preS1 and preS2 sequences. 2. Immunogenicity in poor responders to hepatitis B vaccines. Vaccine 1997; 15:1732-6. [PMID: 9364675 DOI: 10.1016/s0264-410x(97)00118-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The immunogenicity of a yeast-derived recombinant hepatitis B virus (HBV) vaccine containing surface antigen (S) and selected preS1 and preS2 sequences (S-L*) was compared with that of a vaccine containing S alone (Engerix-B) in 32 healthy adults with a previous history of poor response (anti-HBs < 10 mIU ml-1) after at least three consecutive monthly doses of hepatitis B vaccines. The poor responders were randomized to receive three additional 20-microgram doses of either S-L* or Engerix-B in a double-blind fashion according to a 0-, 1-, 2-month schedule. In vivo humoral and in vitro lymphoproliferative responses to the S and preS regions were monitored. Although the addition of the selected preS sequences to S did not enhance the in vivo humoral anti-HBs response, the administration of the three additional vaccine doses, irrespective of their preS content, induced seroprotective anti-HBs levels in most vaccinees (29/32, 91%). In vitro proliferative responses to HBV surface antigens were only observed in subjects displaying anti-HBs titers > 1000 mIU ml-1 after the third additional vaccine dose.
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Affiliation(s)
- G Leroux-Roels
- Department of Clinical Chemistry, University of Gent, Belgium.
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Pollicino T, Zanetti AR, Cacciola I, Petit MA, Smedile A, Campo S, Sagliocca L, Pasquali M, Tanzi E, Longo G, Raimondo G. Pre-S2 defective hepatitis B virus infection in patients with fulminant hepatitis. Hepatology 1997; 26:495-9. [PMID: 9252165 DOI: 10.1002/hep.510260235] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Controversial data were recently published concerning the association of hepatitis B virus (HBV) variants with fulminant hepatitis (FH). In this study, we first analyzed the complete nucleotide sequences of HBV genomes isolated from serum samples from a surgeon and his mother, who was accidentally infected by the son; both died of FH. The infecting viruses were genetically almost identical in both patients; all the clones examined carried a double nucleotide mutation in the start codon of the pre-S2 region that prevented the synthesis of the corresponding protein. Analyses of different serum samples from the son revealed only wild-type precore sequences in a high viremic serum, whereas hepatitis B e antigen (HBeAg)-defective strains were prevalent when the viremia had decreased. Subsequently, we extended the analysis to the viral genomes isolated from 18 additional patients with acute HBV infection and different clinical behaviors: 3 of 5 patients with FH and without previous liver disease had pre-S2 start codon mutations preventing pre-S2 protein synthesis, whereas none of the 13 control cases had similar genomic rearrangements. Analysis of the precore region showed that viral populations normally producing HBeAg were the only or the prevalent viral strains in all of these cases. In summary, our results support the hypothesis that the pre-S2 protein is not essential for HBV infectivity. They also show that infection by pre-S2-defective virus is frequently associated with FH, indicating that this variant might play a pathogenetic role in cases of acute liver failure. Finally, they suggest that the emergence of HBeAg-defective viruses might be a late event in the course of FH, occurring when HBeAg-producing viruses have been mostly cleared.
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Affiliation(s)
- T Pollicino
- Dipartimento di Medicina Interna, Università di Messina, Italy
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Oquendo J, Karray S, Galanaud P, Petit MA. Effect of hepatitis B virus on tumour necrosis factor (TNF alpha) gene expression in human THP-1 monocytic and Namalwa B-cell lines. Res Immunol 1997; 148:399-409. [PMID: 9443579 DOI: 10.1016/s0923-2494(97)82873-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In response to viruses, monocytes and B cells produce TNF alpha. Therefore, we investigated TNF alpha gene expression and protein secretion in a human monocytic cell line, THP-1, and a Burkitt's lymphoma B-cell line, Namalwa, in response to hepatitis B virus (HBV). Stimulation by phorbol myristate acetate (PMA) (100 ng/ml for 48 h) induced TNF alpha secretion in THP-1 and Namalwa cells (100 to 300 pg/ml). In THP cells, the optimum response (> 2000 pg/ml) was obtained in the presence of a second mitogenic signal such as lipopolysaccharide (LPS) (10 microg/ml for 24 h). In our activation conditions, Northern blot analysis revealed a marked accumulation of TNF alpha mRNA species at 1.7 kb in both cell lines. When PMA- or PMA+LPS-stimulated THP-1 cells were exposed to HBV, TNF alpha protein and mRNA significantly decreased (> 50%). In contrast, HBV exposure of PMA-activated Namalwa cells resulted in strongly increased TNF alpha protein secretion (1 ng/ml). In this case, HBV induced TNF alpha mRNA accumulation that consisted of two types: a regular 1.7 kb and two novel high molecular weight (HMW) species at 3.7 and 4.3 kb. Exposure of stimulated THP-1 and Namalwa cells to HBV resulted in HBs and pre-S1 antigen production in the supernatants. In addition, HMW HBV DNA forms were detected in both cell lines, but with distinct HindIII restriction patterns. These findings indicate that TNF alpha gene expression may be differently regulated by HBV in activated human macrophages and B cells, and thus TNF alpha may be involved in the pathogenesis of HBV.
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Affiliation(s)
- J Oquendo
- INSERM Unité 131, Immunopathologie et Immunologie Virale, Clamart, France
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34
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Jannière L, Bidnenko V, McGovern S, Ehrlich SD, Petit MA. Replication terminus for DNA polymerase I during initiation of pAM beta 1 replication: role of the plasmid-encoded resolution system. Mol Microbiol 1997; 23:525-35. [PMID: 9044286 DOI: 10.1046/j.1365-2958.1997.d01-1874.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Replication of plasmid pAM beta 1 is initiated by DNA polymerase I (Pol I) and completed by DNA polymerase III holoenzyme contained in the replisome machinery. In this study we report that initiation of DNA replication generates D-loop structures containing the nascent leading strand paired to its template, and that D-loop extension is arrested approximately 230 bp from the initiation site of DNA synthesis in the presence of the plasmid-encoded resolvase. In vitro and in vivo data suggest that this arrest is caused by a collision between Pol I and the resolvase bound to its target. As the arrested D-loop replication intermediates carry a single-stranded primosome-assembly site, we hypothesize that the biological role of the replication arrest is to limit the region replicated by Pol I and to promote the replacement of Pol I by the replisome in order to initiate concerted synthesis of the leading and lagging strands.
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Affiliation(s)
- L Jannière
- Laboratoire de Génétique Microbienne, Institut National de la Recherche Agronomique, Jouy-en-Josas, France.
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Oquendo J, Dubanchet S, Capel F, Mabit H, Petit MA. Suppressive effect of hepatitis B virus on the induction of interleukin-1 beta and interleukin-6 gene expression in the THP-1 human monocytic cell line. Eur Cytokine Netw 1996; 7:793-800. [PMID: 9010683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The major target organ for Hepatitis B Virus (HBV) is the liver, but extrahepatic sites including monocytes express receptors for HBV and may become infected. Therefore, we investigated the effect of HBV on the in vitro expression of interleukin-beta (IL-1 beta) and interleukin-6 (IL-6) by the monocytoid cell line THP-1, exposed to various stimuli (LPS, PMA or both). Nonstimulated THP-1 cells did not synthesize IL-1 beta and IL-6, even after in vitro exposure to HBV. LPS stimulation alone induced moderate secretion of both IL-1 beta and IL-6 (300 pg/ml). After induction of macrophage differentiation by PMA, THP-1 cells acquired adherence and expressed a higher level of IL-1 beta (up to 2 ng/ml) but did not synthesize IL-6. Treatment of THP-1 cells with PMA and LPS caused the highest production of both IL-1 beta and IL-6 (> 5ng/ml). In vitro exposure of PMA + LPS-stimulated THP-1 cells to HBV resulted in secretion of both HBsAg and preS2Ag which was maintained over 10 days of culture. Southern blot technique was used to study the state of HBV DNA in the cells. Hybridization of non-digested cellular DNA showed only high molecular weight HBV DNA forms. The HindIII restriction pattern revealed bands corresponding to large DNA fragments and the presence of bands at the 3.2 kb position. Under these conditions (PMA + LPS), HBV inhibited the production of IL-1 beta and IL-6 proteins and completely suppressed the IL-1 beta and IL-6 mRNA. Thus, our findings (i) strongly support a relationship between the state of cell differentiation and susceptibility of cells to HBV infection, and (ii) demonstrate that HBV exerts an inhibitory effect on the induction of IL-1 beta and IL-6 genes expression in monocytic THP-1 cells. These results suggest that HBV leads to a fall of pro-inflammatory cytokine production by monocytes/macrophages, which may contribute to impaired host immune response during infection.
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Abstract
The promiscuous plasmid pAM beta 1 from Gram-positive bacteria encodes a resolution system which differs from that of Tn3 in that (i) it requires a histone-like protein and an unusual resolvase-DNA interaction to promote recombination and (ii) it mediates in vivo DNA inversion in plasmid substrates. In this in vivo analysis, the pAM beta 1 resolution site is narrowed down to a 99 bp segment, the strand exchange is mapped within 10 bp and the serine residue at position 10 of the resolvase is shown to be essential for enzyme activity. In addition, data showing that the resolution system does not promote DNA inversion in the Bacillus subtilis chromosome are presented. Implications of this observation are discussed.
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Affiliation(s)
- L Jannière
- Laboratoire de Génétique Microbienne, Institut National de la Recherche Agronomique, Jouy en Josas, France
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38
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Berthillon P, Crance JM, Leveque F, Jouan A, Petit MA, Deloince R, Trepo C. Inhibition of the expression of hepatitis A and B viruses (HAV and HBV) proteins by interferon in a human hepatocarcinoma cell line (PLC/PRF/5). J Hepatol 1996; 25:15-9. [PMID: 8836896 DOI: 10.1016/s0168-8278(96)80322-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
AIMS/METHODS PLC/PRF/5 is a continuous human hepatocarcinoma cell line whose genome contains integrated HBV DNA and which secretes two of the hepatitis B virus envelope proteins (HBs and PreS2). This line is also susceptible to infection by hepatitis A virus and was therefore used to compare the effects of interferon on protein synthesis of these two viruses and to assess the interactions which occur between them during infection. RESULTS Results showed that recombinant interferon alpha 2-a inhibited the expression of the two hepatitis B virus envelope antigens (HBs and PreS2) and of the only hepatitis A virus antigen in a dose-dependent fashion. Comparison of the effect of interferon on antigenic protein production of these two viruses, showed stronger inhibition of hepatitis A virus capsid antigen than of hepatitis B virus envelope antigens. Infection with hepatitis A virus also downregulates the expression of the two hepatitis B virus proteins. CONCLUSIONS Considering the absence of cytotoxic effects from the doses used, this study confirms the relevance of this cellular model for the study of antiviral cytokines in vitro. It also provides a further rationale for the clinical evaluation of the therapeutic potential of interferons in severe hepatitis cases due either to hepatitis A virus alone or to superinfection of hepatitis B virus carriers by hepatitis A virus.
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Kremsdorf D, Garreau F, Capel F, Petit MA, Brechot C. In vivo selection of a hepatitis B virus mutant with abnormal viral protein expression. J Gen Virol 1996; 77 ( Pt 5):929-39. [PMID: 8609489 DOI: 10.1099/0022-1317-77-5-929] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
We have investigated the molecular basis for the in vivo selective advantage of a hepatitis B virus (HBV) mutant. We have determined the complete nucleotide sequences of the major HBV forms identified at the beginning (B1-83) and end (B1-89) of a 6 year follow-up of a chronically infected patient. The B1-89 sequence showed marked nucleotide rearrangements (a nucleotide divergence of 11.3 % compared with the adw2 subtype), but sequence comparison showed that both viral molecules were of common origin (62/138 mutations were found on both molecules, compared to adw2). In vitro transfection of Huh7 cells showed important modifications in B1-89 viral protein expression. We observed a decrease in B1-89 envelope protein expression associated with a modification of the migration pattern of the large envelope protein. For the B1-89 capsid protein, an insertion of 36 nucleotides at the 5' end of the C gene resulted in increased expression of a core-specific protein of abnormal size (24 kDa versus 22 kDa). Finally, our data also suggest an increase in the transcomplementation efficiency of the mutated B1-89 polymerase protein. Thus, we were able to demonstrate distinct intrinsic properties of HBV DNA molecules isolated from a chronic carrier with virus multiplication at different times during infection. Modifications of viral protein expression in the mutated form illustrate strategies used by the virus to prevent clearance and to contribute to viral persistence.
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Affiliation(s)
- D Kremsdorf
- Institut National de la Santé et de la Recherche Médicale U.370, Paris, France
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40
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Abstract
BACKGROUND/AIMS We analyzed the hepatitis B virus envelope specificities (HBs, preS2 and preS1) involved in virus attachment to normal human hepatocytes, and we performed in vitro hepatitis B virus infection experiments without addition of dimethyl sulfoxide and polyethylene glycol, which may affect cell membrane integrity, in order to study further the early steps of the life cycle of the hepatitis B virus. METHODS Primary normal human hepatocytes were prepared from surgical biopsies by the two-step collagenase perfusion technique, and cultured in a fetal calf serum-free medium supplemented with 10(-6) M dexamethasone. Cell-binding assays, ligand blotting and immunohistochemistry experiments were carried out using our anti-idiotypic (Ab2) antibodies (Ab2s/preS1, Ab2s/preS2 and Ab2s/HBs). RESULTS Probing primary normal human hepatocytes, the 35-kDa major preS1-binding protein (preS1-BP35) we have previously identified in human hepatoma HepG2 cells was recognized in blotting, whereas both HBs- and preS1-specificities of the hepatitis B virus envelope interacted strongly with normal human hepatocyte cell membrane in cell-binding assays and immunohistochemistry experiments. Hepatitis B virus infectivity studies confirmed a great inter-experimental variability depending on donors and liver perfusion, and demonstrated a great intra-experimental variability depending on the serum-derived hepatitis B virus isolate used for the inoculation. In our culture conditions, only increased detection of the RC and CCC DNA forms of hepatitis B virus in cells and of hepatitis B virus surface antigens in medium was observed 4 to 8 days after exposure of cells to hepatitis B virus. CONCLUSION These findings support a potential role for preS1-BP35 as a receptor protein for hepatitis B virus. In our hands, limitation(s) in the hepatitis B virus life cycle may occur at some step after virion binding, and likely result from complex regulation of reverse transcription of the RNA and translation of core protein by extrahepatic host factors or/and by the virus itself. However, the normal human hepatocyte model developed here is available for studying the initial steps in hepatitis B virus entry into cells.
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Affiliation(s)
- H Mabit
- Institut National de la Santé de la Recherche Médicale Unité, Unité, Clamart, France
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41
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Zoulim F, Capel F, Berthillon P, Trépo C, Petit MA. [Clinical and virological evaluation of the detection of pre-S1 and pre-S2 antigens in serum from patients with chronic hepatitis B]. Gastroenterol Clin Biol 1995; 19:970-5. [PMID: 8729407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVES AND METHODS We performed a prospective study to determine the clinical and virological significance of pre-S antigen detection in serum samples from patients with chronic hepatitis B virus infection. Four hundred thirty seven consecutive serum samples from 116 patients were tested for the presence of both pre-S1 and pre-S2 antigens by radioimmunoassay using specific monoclonal antibodies. RESULTS The pre-S1 antigen/HBs antigen ratio, gave an estimation of the number of pre-S1 epitopes expressed on the surface of circulating viral particles, and was positively correlated with the intensity of viral replication intensity (P < 0.05). Moreover, the pre-S1 antigen/HBs antigen ratio was significantly higher in patients suffering from chronic hepatitis associated with viral replication (24% +/- 13); in anti-HBe positive patients, the pre-S1 antigen/HBs antigen ratio was higher in patients replicating a HBe antigen minus variant of the hepatitis B virus and suffering from chronic hepatitis (17% +/- 9) than in asymptomatic HBs antigen carriers (5% +/- 6) (P < 0.05). The pre-S2 antigen/HBs antigen ratio was not correlated with the level of viral replication or with the patient's clinical status. CONCLUSION This study confirms that pre-S1 antigen detection is a reliable marker of hepatitis B virus replication which can be easily performed in chronically infected patients. This assay is especially useful in identifying anti-HBe positive carriers who replicate a minus pre-core mutant and could benefit from antiviral therapy.
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Affiliation(s)
- F Zoulim
- Service d'Hépato-Gastroentérologie, Hôtel-Dieu, Lyon
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42
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Abstract
The broad-host-range plasmid pAM beta 1 from Gram-positive bacteria encodes a resolvase, designated Res beta, which shares homology with the proteins of the resolvase-invertase family. Here we report the purification and in vitro characterization of Res beta. This resolvase is particular in two aspects: it has an atypical binding site and requires a cofactor to promote resolution in vitro. Res beta binds to two regions within its resolution site res. One contains two inverted repeats (R1 and R2), the other contains only one repeat (R3). The cofactor required for resolution in vitro is present in crude extracts of both Bacillus subtilis and Escherichia coli and can be substituted by the E. coli histone-like protein HU. The possible mode of action of HU in the resolution process is discussed.
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Affiliation(s)
- M A Petit
- Laboratoire de Génétique Microbienne, Jouy en Josas, France
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43
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Ganne-Carrié N, Kremsdorf D, Garreau F, Thévenin M, Petit MA, Nalpas B, Bréchot C. Effects of ethanol on hepatitis B virus Pre-S/S gene expression in the human hepatocellular carcinoma derived HEP G2 hepatitis B DNA positive cell line. J Hepatol 1995; 23:153-9. [PMID: 7499786 DOI: 10.1016/0168-8278(95)80329-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
BACKGROUND/AIMS Among the reported interactions between ethanol and hepatitis B virus (HBV), studies of transgenic mice have suggested an effect of ethanol on the secretion of viral envelope proteins. METHODS We further investigated these interactions in vitro by determining HBs antigen levels and performing northern blots of viral mRNA in human cell culture (HepG2 HBV positive cells) exposed for 3 to 12 days to various concentrations of ethanol. RESULTS In cultures exposed to 200 mM ethanol, HBs antigen concentrations increased in the medium (p < 0.05) after 3 days as Pre-S1 and Pre-S2 protein concentrations. This increase was not specific, as albumin and ferritin increased in the same proportions. Ethanol also increased the HBs antigen concentration in the cells (p < 0.05), whereas levels of viral mRNA encoding surface proteins were unaffected. CONCLUSIONS These findings show that short-term ethanol exposure in vitro can induce HBs antigen overexpression via a post-transcriptional mechanism.
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Rosmorduc O, Petit MA, Pol S, Capel F, Bortolotti F, Berthelot P, Brechot C, Kremsdorf D. In vivo and in vitro expression of defective hepatitis B virus particles generated by spliced hepatitis B virus RNA. Hepatology 1995; 22:10-9. [PMID: 7601398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/06/2022]
Abstract
The mechanisms involved in hepatitis B virus (HBV) persistence are still poorly understood. We have previously shown that the encapsidation of the singly spliced 2.2 kb-HBV RNA leads to the secretion of circulating HBV defective particles in patients with chronic hepatitis. We have now investigated the presence of the HBV defective particles in sera from patients with acute and chronic hepatitis, using polymerase chain reaction. These defective particles were detected in a larger amount in sera of patients with acute hepatitis that progressed to chronic hepatitis, or had already developed chronic hepatitis, as compared with those who recovered from acute hepatitis (the increase was estimated to be an average of 50-fold). In addition, we showed that the presence of these defective HBV particles is closely associated with the chronic course of hepatitis B virus infection and with viral multiplication. We also analyzed viral RNAs and proteins synthetized after in vitro transfection of Huh7 cell line with the corresponding defective hepatitis B virus DNA molecule. We showed that expression of the defective hepatitis B virus DNA alone leads to a marked intracellular accumulation of the major core protein (HBcAg) and to an increased secretion of hepatitis B e antigen (HBeAg). These observations may be consistent with a role of these defective hepatitis B virus (HBV) particles in viral persistence.
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45
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Mabit H, Dubanchet S, Capel F, Dauguet C, Petit MA. In vitro infection of human hepatoma cells (HepG2) with hepatitis B virus (HBV): spontaneous selection of a stable HBV surface antigen-producing HepG2 cell line containing integrated HBV DNA sequences. J Gen Virol 1994; 75 ( Pt 10):2681-9. [PMID: 7931154 DOI: 10.1099/0022-1317-75-10-2681] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The degree of susceptibility of human hepatoma (HepG2) cells to direct hepatitis B virus (HBV) infection remains unknown. We previously observed a low level of Dane particle production and viral DNA replication after in vitro infection of HepG2 cells with serum-derived HBV. However, this culture system appeared to be affected by variations as human hepatocyte cultures. In the present study, HBV infection of HepG2 cells led to a significant increase in the secretion of three envelope antigens (HBsAg, preS2Ag and preS1Ag) at 4 days post-infection, and Northern blot analysis revealed the presence of both preS1 (2.6 kb) and preS2/S (2.2 kb) transcripts. Expression of preS1Ag and the corresponding viral RNA became undetectable on 21 days post-infection whereas the 2.2 kb RNA species persisted and was associated with secretion of subviral HBs particles expressing preS2-epitopes and banding between 30 and 35% sucrose. At 35 days post-infection (fifth passage), a sudden high level production of HBsAg and preS1Ag was observed, followed by a massive cell death (90%). A stable HBsAg-producing HepG2 cell line, designated HepG2-BV3, grew out of the surviving cells. HepG2-BV3 cells could integrate HBV DNA sequences and produce the three HBV surface antigens. Treatment with dexamethasone increased the HBsAg and preS1Ag secretion. Such a HBsAg-producing HepG2 cell line obtained by in vitro HBV infection seems to mimick events that occur in the naturally occurring persistent chronic infection, and therefore may be an efficient in vitro model for studying the contribution of viral integration in the dysregulation of HBV and liver-specific genes expression.
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Affiliation(s)
- H Mabit
- INSERM Unité 131, Clamart, France
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46
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Petit MA, Bedale W, Osipiuk J, Lu C, Rajagopalan M, McInerney P, Goodman MF, Echols H. Sequential folding of UmuC by the Hsp70 and Hsp60 chaperone complexes of Escherichia coli. J Biol Chem 1994; 269:23824-9. [PMID: 7916347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Replication-blocking lesions generate a signal in Escherichia coli that leads to the induction of the multigene SOS response. Among the SOS-induced genes are umuD and umuC, whose products are necessary for the increased mutation rate in induced bacteria. The mutations are likely to result from replication across the DNA lesion, and such a bypass event has been reconstituted in vitro (Rajagopalan, M., L, C., Woodgate, R., O'Donnel, M., Goodman, M. F., Echols, H. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 10777-10781). In this work, we show that the chaperone proteins promote the proper folding of UmuC protein in vitro. We treated purified and inactive UmuC with Hsp70 and Hsp60. After Hsp70 treatment, the DNA binding activity of UmuC was recovered, but the ability to promote replication across DNA lesions was not. However, lesion bypass activity was recovered upon further treatment with Hsp60. The biological significance of such a folding pathway for UmuC protein is strengthened by in vivo evidence for a role of DnaK in UV-induced mutagenesis.
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Affiliation(s)
- M A Petit
- Division of Biochemistry and Molecular Biology, University of California, Berkeley 94720
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47
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Petit MA, Zoulim F, Berthillon P, Capel F, Li J, Dauguet C, Ferrari C, Trépo C. PreS1 antigen/antibody patterns following interferon therapy in acute and chronic hepatitis B. J Hepatol 1994; 20:47-56. [PMID: 8201222 DOI: 10.1016/s0168-8278(05)80466-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The relation between preS1 antigen/antibody system and different phases of hepatitis B virus infection were studied in 425 serum samples from 50 hepatitis B patients before, during and after antiviral therapy using interferon alone or in combination with corticosteroid withdrawal. A typical profile of self-limited acute hepatitis B was characterized by hepatitis B virus-DNA clearance using polymerase chain reaction and preS antigens using monoclonal radioimmunoassays and by antibody responses to the middle and the large HBs proteins (gp33/gp36 and p39/gp42) using immunoblotting quantitative analysis. After interferon therapy in patients with protracted hepatitis B, complete eradication of the virus was observed in 70% of patients, and antibody response directed to middle HBs and large HBs proteins could be induced. Conversely, this antibody response was never detected in follow-up studies of chronic active hepatitis B patients who responded well to antiviral therapy and lost HBs, preS2 and preS1 antigens. Most interesting, in 50% of patients with HBeAg-positive chronic active hepatitis B who received combination therapy and in 67% of patients with anti-HBe-positive chronic active hepatitis B given interferon alone, the elevated serum preS1Ag/HBsAg ratio persisted after treatment was discontinued and even increased until the end of the follow-up when hepatitis B virus DNA was undetectable in serum by the conventional hybridization technique. This rebound of preS1 antigen expression following antiviral therapy in patients with chronic active hepatitis B may indicate virus persistence, suggesting the possibility of relapse through wild-type hepatitis B virus or the emergence of hepatitis B virus mutants.
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Kremsdorf D, Garreau F, Duclos H, Thiers V, Schellekens H, Petit MA, Bréchot C. Complete nucleotide sequence and viral envelope protein expression of a hepatitis B virus DNA derived from a hepatitis B surface antigen-seronegative patient. J Hepatol 1993; 18:244-50. [PMID: 8409340 DOI: 10.1016/s0168-8278(05)80252-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
An HBV strain isolated from a patient lacking conventional serological markers of HBV infection was characterized. The complete nucleotide sequence was determined following PCR amplification. Only 22 nucleotide substitutions were found relative to the reported sequence of the ayw subtype. Five of these point mutations in the preS/S and preC/C genes led to amino acid substitutions and, with one exception, were located in regions coding for antigenic determinants of viral envelope or capsid proteins. Eight amino acid substitutions were located in terminal protein and the spacer domain of the polymerase gene product. Despite these amino acid changes, transient expression of the preS2 and S envelope proteins in eucaryotic cells yielded viral proteins detectable in the culture medium with polyclonal and monoclonal anti-preS2 and -S antibodies. These data conclusively demonstrate persistent infection by HBV in subjects without HBV serological markers. The absence of conventional HBV serological markers is probably due to several factors: a low level of viral replication, some genetic modifications, as well as an abnormal immune response to the virus.
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Hoffmann HJ, Lyman SK, Lu C, Petit MA, Echols H. Activity of the Hsp70 chaperone complex--DnaK, DnaJ, and GrpE--in initiating phage lambda DNA replication by sequestering and releasing lambda P protein. Proc Natl Acad Sci U S A 1993; 89:12108-11. [PMID: 1361234 PMCID: PMC50707 DOI: 10.1073/pnas.89.24.12108] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Initiation of DNA replication by phage lambda requires the ordered assembly and disassembly of a specialized nucleoprotein structure at the origin of replication. In the disassembly pathway, a set of Escherichia coli heat shock proteins termed the Hsp70 complex--DnaK, DnaJ, and GrpE--act with ATP to release lambda P protein from the nucleo-protein complex, freeing the DnaB helicase for its DNA-unwinding reaction. To investigate the mechanism of the release reaction, we have examined the interaction between P and the three heat shock proteins by glycerol gradient sedimentation and gel electrophoresis. We have discovered an ATP-dependent ternary interaction between P, DnaK, and DnaJ; this P.DnaK.DnaJ complex is dissociated by GrpE. We have concluded that the function of the Hsp70 complex in sequestering and releasing P protein provides for the critical step in the disassembly pathway. Based on our data and other work on protein folding, the formation of the P.DnaK.DnaJ complex might involve a conformational shift to a folding intermediate of P.
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Affiliation(s)
- H J Hoffmann
- Division of Biochemistry and Molecular Biology, University of California, Berkeley 94720
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Abstract
Hepatitis B virus (HBV) serology has become extremely refined. As well as the recognised hepatitis B surface (HBs), hepatitis B core (HBc), and hepatitis B e (HBe) antigen-antibody systems, new markers have been introduced including pre-S1, pre-S2 for the envelope and the functional X protein. New automates have been introduced allowing flexibility in the different tests according to precise needs. The monitoring of pre-S1 antigen provides a relevant correlate of viral replication. The quantitative determination of HBV-DNA, pre-S1 Ag, and IgM anti-HBc seem most useful for the decision to use, and the monitoring of, antiviral treatment. Second generation ELISAs detect antibodies to three sets of hepatitis C virus (HCV) protein including the c22 core, and c33, and c100, which correspond to the non-structural regions (NS3 and NS4, respectively). Second generation ELISAs require confirmation by supplement assays, but their biggest limitation is the delayed appearance of anti-HCV after primary infection. In addition 10% of chronic infections with liver disease still remain seronegative despite circulating HCV RNA in serum or liver, or both. Much progress still has to be made before HCV serology can reach the level of sophistication of HBV.
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