Chemical sex (chemsex) in a population of French university students

Introduction

Chemsex is defined by the use of psychoactive substances to facilitate or improve sexual relations. Our objectives were to assess the prevalence of the practice of ‘chemsex’ in a population of French university students and to identify socio-demographic and clinical factors associated with this practice.

Material and methods

We have used an anonymous online questionnaire comprising 15 questions on socio-demographic characteristics, chemsex use, sexual satisfaction, the type of substances used in this sexual context and their route of administration.

Results

A total of 680 people were included in our study. Among them, 22.5% reported chemsex behaviour in the past year. Using a multivariate analysis, factors associated with chemsex were dating application use (p = 0.049) and pornography use [viewing more than once per month (p = 0.002)]. Having a sexual partner involved in chemsex (p < 0.0001), celibacy (p = 0.007), sexual orientations other than heterosexual (p = 0.0013) and especially bisexuality (p = 0.0002) were also significantly associated with chemsex.

Conclusion

This is the first study reporting a high prevalence of chemsex in a university student population. Further larger studies should be conducted to confirm these results showing a high prevalence of this at-risk behaviour.

Characteristics of prescription in 29 Level 3 Neonatal Wards over a 2-year period (2017-2018). An inventory for future research

Objectives

The primary objective of this study is to determine the current level of patient medication exposure in Level 3 Neonatal Wards (L3NW). The secondary objective is to evaluate in the first month of life the rate of medication prescription not cited in the Summary of Product Characteristics (SmPC). A database containing all the medication prescriptions is collected as part of a prescription benchmarking program in the L3NW.

Material and methods

The research is a two-year observational cohort study (2017–2018) with retrospective analysis of medications prescribed in 29 French L3NW. Seventeen L3NW are present since the beginning of the study and 12 have been progressively included. All neonatal units used the same computerized system of prescription, and all prescription data were completely de-identified within each hospital before being stored in a common data warehouse.

Results

The study population includes 27,382 newborns. Two hundred and sixty-one different medications (International Nonproprietary Names, INN) were prescribed. Twelve INN (including paracetamol) were prescribed for at least 10% of patients, 55 for less than 10% but at least 1% and 194 to less than 1%. The lowest gestational ages (GA) were exposed to the greatest number of medications (18.0 below 28 weeks of gestation (WG) to 4.1 above 36 WG) (p<0.0001). In addition, 69.2% of the 351 different combinations of an medication INN and a route of administration have no indication for the first month of life according to the French SmPC. Ninety-five percent of premature infants with GA less than 32 weeks received at least one medication not cited in SmPC.

Conclusion

Neonates remain therapeutic orphans. The consequences of polypharmacy in L3NW should be quickly assessed, especially in the most immature infants.

Klebsiella pneumoniae and Klebsiella oxytoca meningitis in infants. Epidemiological and clinical features

BACKGROUND

The incidence of meningitis caused by Klebsiella pneumoniae (Kp) and Klebsiella oxytoca (Ko) in high-income countries is unknown, and no series have been published to date.

METHODS

We conducted a nationwide multicenter observational study in France between 2006 and 2016. All children from the French national registry for paediatric bacterial meningitis under the age of 1 year and hospitalized for Kp or Ko meningitis were included. Virulence factors of four Klebsiella spp. strains were explored by whole genome sequencing.

RESULTS

Of 1859 cases of meningitis in children under the age of 1 year, 13 cases (0.7%) of Klebsiella spp. meningitis (nine for Kp meningitis and four for Ko meningitis) were registered in the French national registry. Three of the patients died and 50% of the survivors had developmental delays.

CONCLUSIONS

Prematurity, low birth weight, and congenital anomalies of the urinary tract appear to be risk factors for Klebsiella spp. meningitis as well as virulence factors of the strain.

Review shows that using surfactant a number of times or as a vehicle for budesonide may reduce the risk of bronchopulmonary dysplasia

AIM

Bronchopulmonary dysplasia (BPD) remains the most common respiratory morbidity in immature infants. This review describes the diagnosis of BPD has evolved and summarises the therapeutic approaches that have made it possible to limit the incidence of BPD.

METHOD

We reviewed the literature from the first definition of BPD by Northway in 1967 to the surfactant treatment policies that are currently in use, drawing on more than 50 papers up to 2017.

RESULTS

Our review showed that improvements in neonatal survival have been associated with an increased risk of severe BPD, significant levels of long-term morbidity and the increased use of healthcare resources. These issues have encouraged researchers to explore potential new treatments that limit the incidence of BPD. Repeated surfactant instillation and the use of surfactant as a vehicle for budesonide are promising strategies for alleviating the burden of chronic lung disease. Ongoing research on surfactant or stem cell therapy may further improve the respiratory prognosis for prematurely born children.

CONCLUSION

Considerable research has been carried out into the increase in BPD, which has resulted from improvements in neonatal survival. Key areas of research include repeated surfactant administration, using surfactant as a vehicle for budesonide and stem cell therapy.

Late Surfactant Administration in Very Preterm Neonates With Prolonged Respiratory Distress and Pulmonary Outcome at 1 Year of Age: A Randomized Clinical Trial

IMPORTANCE

Although immature neonate survival has improved, there is an increased risk of developing bronchopulmonary dysplasia, leading to significant respiratory morbidity. Measures to reduce bronchopulmonary dysplasia are not always effective or have important adverse effects.

OBJECTIVE

To evaluate the effect of late surfactant administration in infants with prolonged respiratory distress on ventilation duration, respiratory outcome at 36 weeks' postmenstrual age, and at 1 year postnatal age.

DESIGN, SETTING, AND PARTICIPANTS

Double-blind randomized clinical trial at 13 level III French perinatal centers. Participants included 118 neonates at less than 33 weeks' gestation who still required mechanical ventilation on day 14 (SD, 2) with fraction of inspired oxygen of more than 0.30. All survivors were eligible for follow-up. We performed an intent-to-treat analysis.

INTERVENTIONS

Infants received 200 mg/kg of poractant alfa (surfactant) or air after randomization. At 1 year, after parents' interview, infants underwent physical examination by pediatricians not aware of the randomization.

MAIN OUTCOMES AND MEASURES

The duration of ventilation was the primary outcome. The combined outcome of death or bronchopulmonary dysplasia at 36 weeks' postmenstrual age and respiratory morbidity at 1 year of age were the main secondary outcome measures.

RESULTS

Of the 118 infants who participated in the study, 65 (55%) were male. Fraction of inspired oxygen requirements dropped after surfactant, but not air, for up to 24 hours after instillation (0.36 [0.11] vs 0.43 [0.18]; P < .005). Severe bronchopulmonary dysplasia/death rates at 36 weeks' postmenstrual age were similar (27.1% vs 35.6%; P = .32). Less surfactant-treated infants needed rehospitalization for respiratory problems after discharge (28.3% vs 51.1%; P = .03); 39.5% vs 50% needed respiratory physical therapy (P = .35). No difference was observed for weight (7.8 [1.2] kg vs 7.6 [1.1] kg), height (69 [5] cm vs 69 [3] cm), and head circumference (44.4 [1.7] cm vs 44.2 [1.7] cm) measured at follow-up, nor for neurodevelopment outcome.

CONCLUSIONS AND RELEVANCE

Late surfactant administration did not alter the early course of bronchopulmonary dysplasia. However, surfactant-treated infants had reduced respiratory morbidity prior to 1 year of age.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01039285.

La remédiation cognitive : une stratégie thérapeutique pour les patients présentant des symptômes psychotiques associés à une mutation génétique rare (CNV)

Les jeunes adultes consultant dans les services de psychiatrie générale présentent parfois des symptômes psychotiques associés à un développement atypique (troubles comportementaux dans l’enfance, troubles des apprentissages, etc.). Ces patients constituent un enjeu pour les équipes de psychiatrie adulte : la prise en charge apparaît souvent peu efficiente (intolérance aux traitements, difficulté à établir un projet de réinsertion, etc.). Pour ces cas complexes de « psychoses de l’adolescent », nous proposons dans notre unité de remédiation cognitive (C3RP) une investigation approfondie et multidisciplinaire de la période développementale, de la petite enfance jusqu’à l’émergence des premiers symptômes psychotiques. Cette relecture sémiologique nous permet d’affiner le diagnostic et de proposer un parcours de soin individualisé, combinant des traitements pharmacologiques et des prises en charge rééducatives. Nous présentons ici le cas de Mademoiselle C., jeune femme pour laquelle le diagnostic de schizophrénie a été porté initialement. L’examen neuropsychologique et l’entretien psychiatrique centré sur la petite enfance, associés aux examens biologiques, anatomiques et génétiques nous ont permis de repenser le diagnostic comme un trouble du développement avec symptômes psychotiques dans un contexte d’anomalie génétique de novo (microduplication 17p13.3). Un traitement pharmacologique adapté (aripiprazole, méthylphénidate et S-citalopram) ainsi qu’une rééducation logico-mathématique ont été associés à des programmes de remédiation cognitive (cognition froide et cognition sociale). Pour les aspects attentionnels, exécutifs et mnésiques le programme CRT avec une adaptation spécifique au cursus universitaire a été suivi. En parallèle, le SAMSAH Prepsy a pu ajuster au quotidien les conditions de son apprentissage et l’aider à la réalisation d’une formation d’assistante de librairie. Pour ces jeunes patients complexes avec nécessité cruciale d’un parcours de réhabilitation, la conjonction d’une remédiation et d’un service d’accompagnement au quotidien est décisive pour l’accomplissement des projets professionnels et personnels.

[Impact of cocooning and maternal voice on the autonomic nervous system activity in the premature newborn infant]

INTRODUCTION

Discomfort, pain, and stress have an adverse impact on the psychomotor development in the premature newborn infant. Recent studies indicate that pain and stress are associated with a reduction of parasympathetic outflow. We hypothesized that cocooning associated with the human voice has a favorable impact on parasympathetic activity in the premature newborn infant.

METHOD

We compared heart rate variability (HRV) before and after standardized cocooning phases associated with the human voice and carried out: 1) by the mother and 2) by a third person. HRV was assessed and expressed as an index reflecting the parasympathetic tone.

RESULTS

Ten children were included (median gestational age, 33 weeks (30(+4)-33(+2))). We observed a higher HRV index after the period of cocooning associated with the human voice compared with the baseline measurement (P<0.05), whether the procedure was carried out by the mother or a third person.

CONCLUSION

This study shows that cocooning associated with the human voice enhances HRV in the preterm newborn infant, indicating an increase in parasympathetic activity after cocooning associated with the human voice. However, the impact is similar whether the cocooning associated with the human voice is performed by the mother or a third person. This result suggests that cocooning associated with the human voice carried out either by the mother or a third person contributes to decreasing stress and discomfort in the premature newborn infant.

Effects of environmental tobacco smoke on the pulmonary circulation in the ovine fetus

OBJECTIVE

Epidemiologic studies have highlighted an association between maternal smoking and persistent pulmonary hypertension of the newborn infant. However, the impact of exposure to tobacco smoke on the perinatal pulmonary circulation is currently unknown. The purpose of this study was to assess the pulmonary vascular effects of environmental tobacco smoke in the fetus.

STUDY DESIGN

We performed surgery on 16 fetal lambs and placed catheters in the main pulmonary artery, aorta, and left atrium to measure pressures. An ultrasonic blood flow transducer was placed around the left pulmonary artery to measure blood flow. The ewes were exposed to tobacco smoke for 2 hours. In another set of experiments, the pulmonary vascular response to increased fetal O(2) tension has been assessed after 2 hours of tobacco smoke inhalation or not (control group).

RESULTS

Exposure to tobacco smoke decreased pulmonary blood flow by 30% and elevated pulmonary vascular resistance by 40%. The vasodilator response to increased O(2) tension was blunted after smoke inhalation compared with control animals. Smoke inhalation was associated with a decrease in fetal PaO(2) and SaO(2).

CONCLUSION

Exposure to environmental tobacco smoke in pregnant ewes impairs both basal tone and vascular reactivity of the fetal lung.

Impaired lung function after intubation and mechanical ventilation for surgical ligation of the ductus arteriosus in preterm infants

OBJECTIVE

Significant patent ductus arteriosus (PDA) in the preterm infant has been associated with pulmonary edema and impaired gas exchange. Therefore, surgical ligature of the DA may be required. However, the effects of intubation and mechanical ventilation on the PDA-induced lung dysfunction presently are unknown. The aim of the study was to investigate whether intubation and mechanical ventilation alter pulmonary function in the preterm infant with significant PDA.

DESIGN

A prospective study.

SETTING

The neonatal intensive care unit and department of anesthesiology in a university hospital.

PARTICIPANTS

Preterm infants <32 weeks' gestational age treated with nasal continuous positive airway pressure (NCPAP) and requiring mechanical ventilation for undergoing surgical DA ligature.

INTERVENTIONS

Respiratory, Doppler echocardiographic parameters, and chest x-ray transparencies of the lungs were measured during NCPAP and 2 hours after intubation and starting mechanical ventilation.

MEASUREMENTS AND MAIN RESULTS

Twenty preterm infants (gestational age = 27 ± 1 wk, birth weight = 950 ± 140 g) were included. Heart rate, O(2) need, PaCO(2), and plasma lactate concentrations were significantly higher after intubation. The mean oxygenation index increased from 1.5 ± 0.6 to 7.2 ± 3 (p < 0.05). The overall transparencies of the lungs decreased after intubation. DA diameter, shortening fraction of the left ventricle, left pulmonary artery blood flow velocities, and left atrium/aorta did not change.

CONCLUSION

In preterm infants with significant PDA, intubation and mechanical ventilation before surgical DA ligation may increase the O(2) need and PaCO(2) and may promote lung edema formation. Mechanical ventilation-induced impairment in lung function is not associated with a change in pulmonary or systemic circulation or DA flow. Special care should be taken to prevent respiratory failure when intubation and mechanical ventilation are required for undergoing surgical DA ligation in the preterm infant.

Rebound in the incidence of pneumococcal meningitis in northern France: effect of serotype replacement

AIM

To determine whether the recent emergence of nonvaccine pneumococcal serotypes has affected the incidence of pneumococcal meningitis in children a few years after the introduction of the heptavalent pneumococcal conjugate vaccine.

METHODS

We conducted a multicentre retrospective cohort study from 2005 to 2008 in all hospitals with paediatric units in northern France. It included all patients < 18 years of age who were admitted for laboratory-confirmed pneumococcal meningitis during the study period. Data were collected from medical files and laboratory records at each hospital and compared with the regional hospital discharge codes. We assessed global and age-specific incidence rates of pneumococcal meningitis from 2005 through 2008, compared them with those from the prevaccine era (2000-2002) and evaluated pneumococcal serotypes.

RESULTS

In all, 41 cases were found during the study period. The incidence rate of pneumococcal meningitis varied from 0.8/100,000 children < 18 years in 2005 to 1.8/100,000 children in 2008 (2.2-fold increase, p = 0.06); and from 1.8 to 11.9/100,000 children < 2 years (6.5-fold increase, p = 0.004). This increase was caused by nonvaccine pneumococcal serotypes.

CONCLUSION

The incidence of pneumococcal meningitis in infants has rebounded in northern France during the pneumococcal conjugate vaccine programme, with the emergence of nonvaccine pneumococcal serotypes.

[Increased success rate in umbilical venous catheter positioning by posterior liver mobilization]

OBJECTIVE

To evaluate prospectively the benefit of posterior liver mobilization during umbilical venous catheterization to place the umbilical venous catheter (UVC) in the central position (inferior vena cava).

PATIENTS AND METHODS

Sixty-five successive newborn infants admitted in 3 neonatal intensive care units who required a UVC were enrolled over a 4-month period. UVC positions were assessed by X-ray. UVCs were placed either in an adequate position (at the right atrial-inferior vena cava junction, indicating success) or inserted within the portal system (failure). In this case, the UVC was drawn back to the 3cm mark and then, an additional attempt to insert the UVC was made during lateroposterior liver mobilization by the operator's hand. The success and failure rates at 1st and 2nd attempts were evaluated and compared. Characteristics of the population and possible catheter-related complications were recorded.

RESULTS

A total of 31 of 65 (55%) UVC insertions failed at the 1st attempt. Among these UVCs, 16 (52%) were correctly repositioned in the central position by hepatic mobilization. The success rate increased by 50% (p<0.05). No life-threatening complications were observed during the procedure.

CONCLUSION

Hand liver mobilization during umbilical venous catheterization improves the rate of adequate insertion of the UVC into the inferior vena cava. It is a simple, quick, and safe procedure.

[Lactation counselling support provided to mothers of preterm babies who intend to breastfeed. Evaluation of an educational intervention in a level III perinatal unit]

OBJECTIVE

To evaluate the educational intervention provided in a perinatal unit to support mothers of preterm babies who intend to breastfeed.

PATIENTS AND METHODS

The study was prospective and included all the infants born between 30 and 34 weeks of gestation at the Jeanne-de-Flandre university hospital in Lille and whose mothers intended to breastfeed. The studied period extended from January to December 2005, comparing the first and the last semester. The different actions were guided by the formation of the staff and lactation counselling to mothers, especially in the initiation of lactation. They were provided by one full-time nurse who was lactation consultant. The main outcome measure was the time to the first breast milk expression. Secondary outcome was the rate of infants breastfed at discharge.

RESULTS

Twenty-one educational interventions were organised for all the people working in the unit. One hundred thirty-two nurses and 17 doctors attended to these sessions. During the study period, 175 babies were born preterm at a gestational age between 30 and 34 weeks: 81 during the first semester and 94 during the second. The two populations were comparable for gestational age and the social class of the mothers, but the birth weight was higher during the second semester (1681+/-140 vs 1774+/-216 g, P=0, 01). Mothers of 65.1% of the neonates intended to breastfeed. The time of the first breast milk expression decreased significatively during the second semester (37,5 vs 30,7 h, P<0, 01). The rate of exclusively or partially breastfed neonates at discharge was stable (88,5 vs 91,9%, ns).

CONCLUSION

The program improved the initiation of lactation. This work emphasises the difficulties and the different steps necessary to promote breastfeeding in preterm babies with respect to developmental care.

Ultradian cycles in mice: definitions and links with REMS and NREMS

Sleep can be organized in two quite different ways across homeothermic species: either in one block (monophasic), or in several bouts across the 24 h (polyphasic). Yet, the main relationships between variables, as well as regulating mechanisms, are likely to be similar. Correlations and theories on sleep regulation should thus be examined on both types of sleepers. In previous studies on monophasic humans, we have shown preferential links between the number of ultradian cycles and the rapid eye movement sleep (REMS) time, rather than with its counterpart non-rapid eye movement sleep (NREMS). Here, the sleep of 26 polyphasic mice was examined, both to better describe the NREMS distribution, which is far more complex than in humans, and to replicate the analyses performed on humans. As in humans, the strongest links with the number of cycles were with REMS. Links were not significant with NREMS taken as a whole, although positive correlations were found with the NREMS immediately preceding REMS episodes and inversely significant with the residue. This convergence between monophasic and polyphasic patterns supports the central role played by REMS in sleep alternation.

Continuation of treatment with infliximab in ankylosing spondylitis: 2-yr open follow-up

OBJECTIVE

To evaluate the continuation and safety of treatment with infliximab in ankylosing spondylitis (AS) over a 2-yr period.

METHODS

This study was an open, observational, 2-yr extension study of an open-label study of three induction infusions of infliximab in refractory AS. The fourth infusion was performed only in case of relapse. Thereafter, infliximab was to be administered as needed according to the rheumatologist's opinion; however, for some patients, infusions were performed systematically.

RESULTS

None of the 50 recruited patients was lost to follow-up. Thirteen patients (26%) interrupted their treatment by infliximab: four for inefficacy, seven for adverse events, of which four were for allergic reactions to the infusion, and two for other reasons. For all of the 46 patients who had had three infusions judged efficacious and well tolerated, a fourth infusion was performed because of a flare of the disease, after a mean interval of 20.3+/-9.9 weeks (range 7.3-57.9). Over the 24 months, the mean interval between infusions was 11.6+/-9.0 weeks. This interval was longer when patients were treated only as needed (mean 14.3+/-12.1 weeks) than systematically (mean 9.8+/-5.7 weeks). Side-effects were similar to those noted in shorter-term studies; seven patients suffered serious adverse events. There were no deaths, no malignancies and no tuberculosis.

CONCLUSION

This study confirms the long-term treatment continuation of infliximab in AS, and shows an acceptable safety profile. It appears that for some patients the disease can be controlled with long intervals between infusions; these findings warrant further studies.

The association between periodontal disease and joint destruction in rheumatoid arthritis extends the link between the HLA-DR shared epitope and severity of bone destruction

OBJECTIVE

To evaluate a possible association between wrist and periodontal destruction in rheumatoid arthritis, and between periodontal destruction, dry mouth, and labial salivary gland biopsy and the contribution of genetic factors (the shared epitope (SE) and IL1B (+3954) or TNFA (-238 or -308) gene polymorphisms).

METHODS

147 patients with rheumatoid arthritis were enrolled. Periodontal damage was defined according to the Hugoson and Jordan criteria on panoramic dental x rays. Typing for the SE and cytokine polymorphisms was undertaken by enzyme linked oligosorbent assay. Odds ratios (OR), relative risk (RR), and chi2 values were calculated to quantify associations.

RESULTS

An association was observed between wrist and periodontal bone destruction (chi2=11.82; p<0.001): 63 patients had both wrist and periodontal destruction, 31 had wrist destruction alone, 20 had periodontal destruction alone, and 33 had no destruction at either site. An association was seen between a positive labial salivary gland biopsy and periodontal bone destruction (RR=2.73 (95% CI, 1.35 to 5.51), p<0.01, n=41) or wrist bone destruction (RR=4.52 (1.96 to 10.45), p<0.001, n=41). The SE was associated with wrist bone destruction (OR=2.5 (1.16 to 5.42), p<0.05) and periodontal bone destruction (OR=2.2 (1.04 to 4.84), p<0.05). No association was found between the selected cytokine polymorphisms and bone destruction.

CONCLUSIONS

A strong association was found between wrist and periodontal bone destruction. The destruction risk was further increased in patients with sicca syndrome. The SE appears to be a severity genetic marker for both wrist and periodontal bone destruction.

Differences in osteocyte density and bone histomorphometry between men and women and between healthy and osteoporotic subjects

Bone defects related to osteoporosis develop with increasing age and differ between males and females. It is currently thought that the bone remodeling process is supervised by osteocytes in a strain-dependent manner. We have shown an altered response of osteocytes from osteoporotic patients to mechanical loading, and osteocyte density is reduced in osteoporotic patients, which might relate to imperfect bone remodeling, leading to lack of bone mass and strength. Hence, information on osteocyte density will contribute to a better understanding of bone biology in males and females and to the assessment of osteoporosis. Osteocyte density as well as conventional histomorphometric parameters of trabecular bone were determined in cancellous iliac crest bone of healthy postmenopausal women and men and of osteoporotic women and men. Osteocyte density was higher in healthy females than in healthy males and lower in osteoporotic females than in healthy females. Bone mass was reduced in osteoporotic patients, both male and female. In females, trabecular number was reduced, whereas in males, trabecular thickness was reduced and eroded surface was increased. There were no correlations between the parameter groups bone architecture, bone formation, bone resorption, and osteocyte density. These results are consistent with impaired osteoblast function in osteoporotic patients and with a different mechanism of bone loss between men and women, in which osteocyte density might play a role. The reduced osteocyte numbers in female osteoporotic patients might relate to imperfect bone remodeling leading to lack of bone mass and strength.

The shared epitope is a marker of severity associated with selection for, but not with response to, infliximab in a large rheumatoid arthritis population

OBJECTIVE

To determine whether joint destruction, indication for, and response to infliximab in rheumatoid arthritis are associated with the shared epitope (SE) or selected cytokine gene polymorphisms (interleukin (IL) 1B, IL1-RN, and tumour necrosis alpha).

METHODS

In a large rheumatoid arthritis population of 930 patients from the same area (Rhône-Alpes, France), patients with (n = 198) or without infliximab treatment (n = 732) were compared according to their genetic status. Clinical, biological, and radiological data were collected. Typing for SE status and cytokine polymorphisms was carried out using enzyme linked oligosorbent assay. Statistical analysis was by chi(2) testing and calculation of odds ratios (OR).

RESULTS

A dose relation was observed between the number of SE copies and joint damage in the whole rheumatoid population (OR, 1 v 0 SE copy = 2.38 (95% confidence interval, 1.77 to 3.19), p<0.001; OR 2 v 0 SE copy = 3.92 (2.65 to 5.80), p<0.001. The SE effect increased with disease duration but was not significant before two years. Selection for infliximab treatment (n = 198) was associated with increased disease activity, joint damage, and the presence of the SE with a dose effect. In all, 66.2% patients achieved an ACR20 improvement. No clinical or genetic factors were able to predict the clinical response to infliximab.

CONCLUSIONS

This post-marketing study in a large cohort of rheumatoid arthritis patients indicates a linkage between rheumatoid arthritis severity, selection for treatment with infliximab, and the presence and dose of the SE.

Cleft lip/palate and CDH1/E-cadherin mutations in families with hereditary diffuse gastric cancer

We report the association of CDH1/E-cadherin mutations with cleft lip, with or without cleft palate (CLP), in two families with hereditary diffuse gastric cancer (HDGC). In each family, the CDH1 mutation was a splicing mutation generating aberrant transcripts with an in-frame deletion, removing the extracellular cadherin repeat domains involved in cell-cell adhesion. Such transcripts might encode mutant proteins with trans-dominant negative effects. We found that CDH1 is highly expressed at 4 and 5 weeks in the frontonasal prominence, and at 6 weeks in the lateral and medial nasal prominences of human embryos, and is therefore expressed during the critical stages of lip and palate development. These findings suggest that alteration of the E-cadherin pathway can contribute to human clefting.

Physiological strains induce differentiation in human osteoblasts cultured on orthopaedic biomaterial

We have developed an in vitro mechanical stretching model of osteoblastic cells cultured on metallic biomaterials in order to study the effects of mechanical strain on osteointegration of orthopaedic implants. Titanium alloy discs coated with alumina or hydroxyapatite were used as substrates. Three Dynacell devices were especially designed to apply cyclic strains on rigid biomaterials. The regimen (600 mu epsilon strains, 0.25Hz) was defined on the basis of physiological data and estimated deformation on hip stem prostheses. The performances of these apparatus were reproducible and provided controlled deformations. Human osteosarcoma cell line MG-63, human osteoblasts obtained from primary cultures and ROS 17/2.8 rat osteosarcoma cells were used as cell models. Cell behaviour was assessed in terms of growth and alkaline phosphatase (ALP) activity by in situ assays for two regimens: 15-min deformations repeated three times a day to mimic rehabilitation exercises and 24-h continuous deformations. We demonstrated that continuous deformation did not affect the growth and ALP activity of MG-63 cells, in contrast with sequential deformations which had no effect on cell number, but which stimulated ALP activity after 5 days of stretching. This sequential regimen can also modify the behaviour of human bone-derived cells resulting in increased proliferation after 5 days and stimulation of ALP activity after 15 days. ROS 17/2.8 rat osteosarcoma cells submitted to sequential deformations responded faster than other cell lines by increasing their ALP activity only after 1 day of stretching. Like MG-63 cells, proliferation of the ROS 17/2.8 rat osteosarcoma cell line was not affected by sequential deformations. This study suggests that short, repeated deformations defined to mimic rehabilitation exercises recommended after prostheses implantation are more likely to exert beneficial effects on implanted bone than continuous strains.

Changes in vasoactive factors associated with altered vessel morphology in the tibial metaphysis during ovariectomy-induced bone loss in rats

We hypothesized that estrogen deficiency induces changes in bone vascularization which might be involved in bone loss mechanisms. First, we studied gene expression of angiogenic (vascular endothelial growth factor (VEGF), fibroblast growth factor-2 (FGF-2)) and vasodilator (endothelial nitric oxide synthase (ecNOS), neuronal NOS (nNOS), inducible NOS (iNOS), PTH-related protein (PTHrP), and its receptor PTH/PTHrP) factors in proximal tibial metaphysis of ovariectomized (OVX) rats and OVX 17beta-estradiol-treated rats at 3, 7, and 14 days. We then evaluated bone and vessel histomorphometry in secondary spongiosae by infusing vessels with a mixture of India ink/barium sulfate after 7 and 14 days of OVX. After 7 days expression of angiogenic and vasodilator factors decreased, concomitant with a decrease in the bone vessel number and possibly area. After 14 days all factors except FGF-2 exhibited either increased or normalized expression, which was associated with the stimulation of both bone formation and resorption. 17beta-Estradiol administration for 7 or 14 days prevented not only the OVX-induced changes in bone remodeling but also the morphological alterations observed in bone vessels. It also prevented the alterations in the expression of genes modified by OVX, except for that of FGF-2 whose transcription was similarly down-regulated in OVX rats with or without estrogen treatment.

Efficacy of infliximab in refractory ankylosing spondylitis: results of a six-month open-label study

OBJECTIVE

To evaluate the efficacy and safety of a loading regimen of the anti-tumour necrosis factor alpha (TNF-alpha) antibody infliximab in predominantly axial severe ankylosing spondylitis (AS).

METHODS

We enrolled in this study 50 patients (76% males, 87% HLA-B27(+), median age 35 yr, median disease duration 13 yr) with active AS [Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) >or=30/100 and serum C-reactive protein concentration >or=15 mg/l) despite treatment with a non-steroidal anti-inflammatory drug, and without peripheral arthritis, uveitis or active inflammatory bowel disease. Other disease-modifying anti-rheumatic drugs were discontinued >or=3 months before inclusion and were not allowed during the study. Patients received three infusions of infliximab (5 mg/kg) at weeks 0, 2 and 6 and were monitored clinically and biologically until week 24.

RESULTS

Forty-eight patients completed the treatment. In intention-to-treat analysis, all parameters were significantly improved at week 2 and generally reached maximal improvement at week 8. The proportion of responders, defined by a reduction of >or=20% in the global assessment of pain (GAP) or by the AS Assessment Study Group (ASAS 20%) criteria, and the proportion of patients reaching partial remission were 98, 94 and 70% respectively. Relapse, defined as >or=50% loss of maximal GAP improvement, occurred in 73% of completers, with a median delay of 14 weeks after the third infusion. No serious adverse event related to the treatment was observed.

CONCLUSIONS

This study confirms, in a large group of severely affected AS patients, the remarkable efficacy of infliximab. Relapse usually occurred after discontinuation of the drug, but almost one-third of completers were still free of relapse 4 months after the last infusion.

Synchrotron radiation microtomography allows the analysis of three-dimensional microarchitecture and degree of mineralization of human iliac crest biopsy specimens: effects of etidronate treatment

Quantitative microcomputed tomography using synchrotron radiation (SR microCT) was used to assess the effects of a sequential etidronate therapy on both three-dimensional (3D) microarchitecture and degree of mineralization of bone (DMB) in postmenopausal osteoporosis. Thirty-two iliac crest biopsy specimens were taken from 14 patients with osteoporosis (aged 64 +/- 1.8 years) before (baseline) and after 1 year of etidronate treatment, and after 2 years of treatment for four of the patients. The samples were imaged at high spatial resolution (voxel size = 10 microm) using the microtomography system developed at the European Synchrotron Radiation Facility (ESRF), Grenoble, France. Three-dimensional microarchitecture parameters were calculated and compared with those obtained from conventional histomorphometry. In addition, the DMB was evaluated also in 3D. No significant statistical changes regarding bone mass and structural parameters were observed in histomorphometry or 3D analyses. The distribution of the DMB in cortical and trabecular bone showed a trend to a shift toward highest mineralization values after 1 year of etidronate treatment (3.88% and 1.24% in cortical and trabecular bone, respectively). This trend was more evident after 2 years. The study also showed that SR microCT is an accurate technique and the only one for quantifying both the mineralization and the microarchitecture of bone samples at the same time in 3D.

Relationships between trabecular bone remodeling and bone vascularization: a quantitative study

Beside its well-known role in bone development, vascularization plays a major role in bone cell migration for bone remodeling and metastatic tumor invasion. However, the various techniques used to identify vessels in bone have never been tested for trabecular bone vessel quantification, whereas bone remodeling quantitative parameters are commonly assessed. In this context, we developed and compared various histological techniques used to visualize blood vessels in rat bone in order to quantify them. First, several products were tested by intracardiac infusion to opacify the bone vascular network. The best results were obtained using either an India ink-1% agarose solution or an India ink-saturated barium sulfate solution followed by X-ray microradiography. Second, to identify the types of vessels, we also performed histoenzymology and immunohistochemistry stainings. Neither alkaline phosphatase (for endothelial cells) nor adenosine triphosphatase (ATPase) stainings (for smooth muscle cells) provided a low enough background to allow for vessel identification and quantification. For immunohistochemistry, various specific vessel constituents were analyzed: laminin, smooth muscle cell alpha-actin, factor VIII, and lectin Griffonia simplifolia. Anti-laminin and anti-smooth muscle cell alpha-actin antibodies gave the best results for quantification. Third, after optimization of these techniques, we performed quantitative bone and vessel histomorphometry on two groups of 12 rats each, for which bone remodeling and vessel number and area parameters were measured. No statistical differences were observed between the two groups, confirming the reproducibility of our measurements. A significant relationship was found between vessel number and histodynamic parameters; that is, bone formation rate correlated positively with India ink-positive vessel area (p < 0.009, r2 = 0.54) and alpha-actin-positive vessel number (p < 0.05, r2 = 0.66). Furthermore, we report reproducible techniques for visualization and quantification of vessels in bone that also allowed for simultaneous conventional bone histomorphometry. This methodology should help researchers to better understand the functional and anatomical relationship between trabecular bone and its vascularization during normal or pathological processes.

Rat hindlimb unloading by tail suspension reduces osteoblast differentiation, induces IL-6 secretion, and increases bone resorption in ex vivo cultures

In this research we utilized tail-suspended rats as an in vivo model for bone loss studies in order to investigate the effects of the tail suspension on the structure of the suspended bones and in ex vivo cultures the activities of trabecular osteoblasts, marrow-derived osteogenic cells, and osteoclasts obtained from treated animals, compared with untreated controls. After a 5-day hind limb unloading, trabecular thinning was already evidenced in the tibial primary spongiosa. In the secondary spongiosa, the bone formation activity was reduced whereas osteoclastic parameters were not yet altered. Bone marrow-derived osteogenic cells and differentiated osteoblasts from enzymatic digestion of posterior limb trabecular bone were prepared from 5 day tail-suspended rats and from normally loaded rats as controls. Cell morphology, alkaline phosphatase (ALPH) activity, production of mineral matrix, osteocalcin, and IL-6 secretion were evaluated in both cell populations. Tail suspension reduced the osteogenic potential of stromal marrow cells and of already differentiated osteoblasts. In fact, ALP positive colonies were significantly reduced in number and were smaller in size compared with controls and bone nodules formed in permissive conditions were also significantly fewer and smaller, whereas in cultures of cells from control conditions, large mineralizing nodules were formed. Osteocalcin secretion was not affected by unloading. Finally, IL-6 concentration was increased in marrow-derived cells from treated rats compared with controls. Primary cultures of osteoclasts were obtained from the nonadherent fraction of the bone marrow of the same animals. The number of TRAP positive cells in culture from tail-suspended rats was significantly increased, as well as bone resorption activity, measured as resorbed surfaces of a suitable synthetic hydroxyapatite, compared with controls. These data clearly suggest that skeletal unloading not only reduces the osteogenic potential of osteoblastic cells but induces an increased osteoclastogenesis and osteoclast activity in ex vivo cultures. They also indicate for the first time that a possible mediator responsible for the increased osteoclastogenesis could be represented by the IL-6 whose secretion by bone marrow cells was significantly enhanced by unloading.

Cell cycling determines integrin-mediated adhesion in osteoblastic ROS 17/2.8 cells exposed to space-related conditions

Six days of microgravity (Bion10 mission) induced dramatic shape changes in ROS 17/2.8 osteoblasts (7). During the Foton 11 and 12 space flights, we studied the kinetics (0-4 days) of ROS 17/2.8 morphology and adhesion, the relationships between adhesion and cell cycle progression after 4 days in space, and osteoblastic growth and activity after 6 days in space. Quantitative analysis of high-resolution adhesion [focal adhesion area imaged by total interference reflection fluorescent microscopy (TIRFM)] and integrin-dependent adhesion (imaged on confocal microscope by vinculin and phosphotyrosine staining) as well as cell cycle phase classification [Ki-67 staining, S-G2, mitotic cells and G1 (postmitotic cells)] were performed using programs validated in parabolic flight and clinostat. We observed disorganization of the cytoskeleton associated with disassembling of vinculin spots and phosphorylated proteins within focal contacts with no major change in TIRFM adhesion after 2 and 4 days of microgravity. Postmitotic cells, alone, accounted for the differences observed in the whole population. They are characterized by immature peripheral contacts with complete loss of central spots and decreased spreading. Osteocalcin, P1CP and alkaline phosphatase, and proliferation were similar in flight cells and 1 g centrifuge and ground controls after 6 days. In conclusion, microgravity substantially affected osteoblastic integrin-mediated cell adhesion. ROS17/2.8 cells responded differently, whether or not they were cycling by reorganizing adhesion plaque topography or morphology. In ROS 17/2.8, this reorganization did not impair osteoblastic phenotype.

Wingless capture by Frizzled and Frizzled2 in Drosophila embryos

A variety of factors could influence how far developmental signals spread. For example, the Patched receptor limits the range of its ligand Hedgehog. Somehow, the Frizzled2 receptor has the opposite effect on its ligand. Increasing the level of Frizzled2 stabilizes Wingless and thus extends the Wingless gradient in Drosophila wing imaginal disks. Here we ask whether Frizzled or Frizzled2 affects the spread of Wingless in Drosophila embryos. We show that in the embryonic epidermis, the combined expression of both receptors is lowest in the engrailed domain. This is because expression of Frizzled is repressed by the Engrailed transcription factor, whereas that of Frizzled2 is repressed by Wingless signaling. Receptor downregulation correlates with an early asymmetry in Wingless distribution, characterized by the loss of Wingless staining in the engrailed domain. Raising the expression of either Frizzled or Frizzled2 in this domain prevents the early disappearance of Wingless-containing vesicles. Apparently, Wingless is captured, stabilized, and quickly internalized by either receptor. As far as we can tell, captured Wingless is not passed on to further cells and does not contribute to the spread of Wingless. Receptor downregulation in the posterior compartment may contribute to dampening the signal at the time when cuticular fates are specified.

[Inaugural symptoms of Horton's disease in a series of 260 patients]

PURPOSE

Horton disease or 'giant cell arteritis' is a known entity in its typical form; the difficulty in diagnosis is due to the atypical signs and symptoms.

METHODS

We review 260 medical files presenting Horton disease between 1979 and 1999 in five different departments: three internal medicine departments, one rheumatology department and one geriatric department.

RESULTS

The study shows a female domination with a mean age of 75 years. Temporal artery biopsy was done on all patients. Ten patients presented a vascular manifestation. The neurological manifestation was the first symptom in four patients. Five patients had cutaneous symptomatology, with positive temporal artery in three cases. Renal manifestation was present in two patients. Two symptoms are important to discuss because of their frequency: the cough and the peripheral arthritis. We found nine observations with arthritis affecting large joints and responding to nonsteroidal antiinflammatories with positive temporal artery biopsy in seven patients, and 21 observations manifesting by cough without radiological signs; in 57% of cases the temporal artery biopsy was positive, and the cough regressed with corticoids.

CONCLUSION

These atypical symptoms have to be known to make a diagnosis and to begin a corticotherapy as soon as possible.

MAPK and SRC-kinases control EGR-1 and NF-kappa B inductions by changes in mechanical environment in osteoblasts

Bone loss occurs in microgravity whereas an increase in bone mass is observed after skeletal loading. This tissue adaptation involves changes in osteoblastic proliferation and differentiation whose mechanisms remain largely unknown. In this context, we investigated the expression and the nuclear translocation of Egr-1 and NF-kappa B, in a simulated microgravity model (clinostat) and in a model of mechanical strain (Flexcell). We performed RT-PCR and immunocytochemistry analyses at baseline and up to 2 h after stimulation (a mitogenic regimen, 1% stretch, 0.05 Hz, 10 min, or clinorotation 50 rpm, 10 min) in osteoblastic ROS17/2.8 cells. Egr-1 induction as well as NF-kappa B nuclear translocation were activated by mechanical changes. PKC downregulation and COX1/2 inhibition did not alter these inductions. In contrast, ERK1/2, p38(MAPK) and src-kinases pathways were differentially involved in both models. Thus, we demonstrated that changes in the mechanical environment induced an activation of Egr-1 and NF-kappa B with specific kinetics and involved various transduction pathways including MAPKs and src-kinases. These could partially explain the later alterations of proliferation observed.

Regulated endocytic routing modulates wingless signaling in Drosophila embryos

Embryos have evolved various strategies to confine the action of secreted signals. Using an HRP-Wingless fusion protein to track the fate of endocytosed Wingless, we show that degradation by targeting to lysosomes is one such strategy. Wingless protein is specifically degraded at the posterior of each stripe of wingless transcription, even under conditions of overexpression. If lysosomal degradation is compromised genetically or chemically, excess Wingless accumulates and ectopic signaling ensues. In the wild-type, Wingless degradation is slower at the anterior than at the posterior. This follows in part from the segmental activation of signaling by the epidermal growth factor receptor, which accelerates Wingless degradation at the posterior, thus leading to asymmetrical Wingless signaling along the anterior-posterior axis.

Influence on bone metabolism of dietary trace elements, protein, fat, carbohydrates, and vitamins

Osteoporosis is a multifactorial disease driven primarily by the genetic factors that control bone metabolism. Among environmental factors, diet may play a key role, affording a target for low-cost intervention. Calcium and vitamin D are well known to affect bone metabolism. Other nutrients may influence bone mass changes; for instance, a number of trace elements and vitamins other than vitamin D are essential to many of the steps of bone metabolism. A wide variety of foods provide these nutrients, and in industrialized countries deficiencies are more often due to idiosyncratic eating habits than to cultural influences. Both culture and vogue influence the amount of carbohydrate, fat, and protein in the typical diet. In children, the current trend is to reduce protein and to increase carbohydrate and fat. Data from epidemiological and animal studies suggest that this may adversely affect bone mass and the fracture risk.

Microgravity inhibits intestinal calcium absorption as shown by a stable strontium test

BACKGROUND

Little is known about the onset and degree of biochemical and functional alterations in calcium metabolism during microgravity.

OBJECTIVE

To evaluate the effect of microgravity on intestinal calcium absorption and calcium-regulating hormones under metabolic ward conditions.

MATERIALS AND METHODS

Fractional calcium absorption (Fc240 in percentage of dose administered) was determined pre-flight, in-flight and post-flight, by use of a stable strontium test in one cosmonaut who spent 20 days in space. Moreover, a sequence of blood samples was collected for the determination of serum parathyroid hormone (PTH), 25-hydroxyvitamin D, calcitriol and serum C-telopeptide (CTx, biomarker of bone resorption) levels. During all periods of data collection, calcium intake was held constant at a minimum level of 1.000 mg day(-1) and a daily supplement of 16.6 microg vitamin D2 was given. Personal ultraviolet (UV) light exposure was measured during the whole mission using a biologically weighting UV dosimeter.

RESULTS

Fc240 was markedly reduced on flight day 19 (4.4%) as compared to pre-flight and post-flight data (13.4% and 17.2%, respectively). Serum calcitriol levels fell from 40.6 pg mL(-1) (mean pre-flight level) to 1.3 pg mL(-1) on flight day 18 and returned into the normal range after recovery. Serum CTx increased during the flight, while serum PTH and 25-hydroxyvitamin D levels did not change significantly.

CONCLUSIONS

Intestinal calcium absorption can be diminished after only three weeks of microgravity. Changes are associated with a severe suppression of circulating calcitriol levels, but are independent of exogenous vitamin D supply and serum PTH levels.

Space flight is associated with rapid decreases of undercarboxylated osteocalcin and increases of markers of bone resorption without changes in their circadian variation: observations in two cosmonauts

BACKGROUND

Microgravity induces bone loss by mechanism(s) that remain largely unknown.

METHODS

We measured biochemical markers related to bone remodeling in two cosmonauts before, during, and after 21- and 180-day space flights, respectively.

RESULTS

During both flights, type I procollagen propeptide and bone alkaline phosphatase decreased as early as 8 days after launch. Undercarboxylated osteocalcin percentage increased early and remained high during both flights. Vitamin K supplementation restored carboxylation of osteocalcin during the long-term flight. Urinary and serum C-telopeptide of type I collagen (CTX) increased as early as day 8 of the flights; the increase was greater in serum than in urine. Pyridinoline, free deoxypyridinoline, and N-telopeptide increased less than CTX during the short-term space flight. The circadian rhythm of bone resorption assessed by urine CTX and free deoxypyridinoline was not altered by microgravity.

CONCLUSION

Vitamin K metabolism or action and bone remodeling may be altered in cosmonauts.

Practice of a testing bench to study the effects of cyclic stretching on osteoblast-orthopaedic ceramic interactions

A new experimental method has been used to study the behaviour of human osteoblasts cultured on bioceramics subjected to mechanical strains. The ceramics were alumina, hydroxyapatite (HA) and a duplex system composed of hydroxyapatite-covered alumina. The system applied 400 microdeformations for a 6-h period with a cycle frequency of 0.5 Hz to osteoblasts growing on ceramic-covered disks. The effects of strains on short-term cell viability, cell growth, alkaline phosphatase (ALP) activity, and collagen biosynthesis were assessed. When possible, the parameters (lactate dehydrogenase) were studied along the experiment in samples of the culture medium, in the other cases by comparison of stretched and unstretched cultures on the same ceramics with the same cell line. In relationship with the coating, mechanical strains resulted in a decrease in DNA corresponding to cell number, an LDH release during straining, an unchanged (alumina) or decreased (HA and duplex) ALP activity, a decrease (HA and duplex) of collagen and total protein synthesis or an increase of it (alumina). The stress-producing device and its associated protocol are shown to be suitable for investigating the behaviour of cells, cultured on biomaterials subjected to mechanical strain.

Effects of long-term microgravity exposure on cancellous and cortical weight-bearing bones of cosmonauts

BACKGROUND

Microgravity has been thought to induce osteoporosis because of reduced weight-bearing. However, up to now, few data have been available about its precise nature and timecourse.

METHODS

We measured bone mineral density (BMD) at the distal radius and tibia in 15 cosmonauts of the Russian MIR space station who sojourned in space either 1 (n=two), 2 (two), or 6 months (11). After recovery periods of similar duration to the space missions, BMD was measured for the 2-month and 6-month crews.

FINDINGS

Neither cancellous nor cortical bone of the radius was significantly changed at any of the timepoints. On the contrary, in the weight-bearing tibial site, cancellous BMD loss was already present after the first month and deteriorated with mission duration. In tibial cortices, bone loss was noted after a 2-month flight. In the 6-month group, cortical bone loss was less pronounced than that for cancellous bone. In some individuals, tibial deterioration was great. Actual BMD did not depend on preceding cumulative periods spent in space. During recovery, tibial bone loss persisted, suggesting that the time needed to recover is longer than the mission duration.

INTERPRETATION

In space, despite physical training, bone loss is an adaptive process that can become pathological after recovery on Earth. Striking interindividual variations in bone responses seem to suggest a need for adequate crew preselection. Targeted treatment or prevention strategies would be useful, not only for space purposes, but also for the increasing number of osteoporotic patients on Earth.

3D micro-computed tomography of trabecular and cortical bone architecture with application to a rat model of immobilisation osteoporosis

Bone mass and microarchitecture are the main determinants of bone strength. Three-dimensional micro-computed tomography has the potential to examine complete bones of small laboratory animals with very high resolution in a non-invasive way. In the presented work, the proximal part of the tibiae of hindlimb unloaded and control rats were measured with 3D MicroCT, and the secondary spongiosa of the scanned region was evaluated using direct evaluation techniques that do not require model assumptions. For determination of the complete bone status, the cortex of the tibiae was evaluated and characterised by its thickness. It is shown that with the proposed anatomically conforming volume of interest (VOI), up to an eight-fold volume increase can be evaluated compared to cubic or spherical VOIs. A pronounced trabecular bone loss of -50% is seen after 23 days of tail suspension. With the new evaluation techniques, it is shown that most of this bone loss is caused by the thinning of trabeculae, and to a lesser extent by a decrease in their number. What changes most radically is the structure type: the remaining bone is more rod-like than the control group's bone. Cortical bone decreases less than trabecular bone, with only -18% after 23 days.

The progeny of wingless-expressing cells deliver the signal at a distance in Drosophila embryos

Pattern formation in developing animals requires that cells exchange signals mediated by secreted proteins. How these signals spread is still unclear. It is generally assumed that they reach their target site either by diffusion or active transport (reviewed in [1] [2]). Here, we report an alternative mode of transport for Wingless (Wg), a member of the Wnt family of signaling molecules. In embryos of the fruit fly Drosophila, the wingless (wg) gene is transcribed in narrow stripes of cells abutting the source of Hedgehog protein. We found that these cells or their progeny are free to roam towards the anterior. As they do so, they no longer receive the Hedgehog signal and stop transcribing wg. The cells leaving the expression domain retain inherited Wg protein in secretory vesicles, however, and carry it forwards over a distance of up to four cell diameters. Experiments using a membrane-tethered form of Wg showed that this mechanism is sufficient to account for the normal range of Wg. Nevertheless, evidence exists that Wg can also reach distant target cells independently of protein inheritance, possibly by restricted diffusion. We suggest that both transport mechanisms operate in wild-type embryos.

Modifications of bone and connective tissue after orthostatic bedrest

Eight male volunteers were submitted to a 6-week anti-orthostatic bedrest trial followed by a 1-month reambulation period. We prospectively monitored whole-body composition by dual-energy X-ray absorptiometry, bone and connective tissue metabolism by biochemical markers and calcium regulating hormones by 1-84 parathyroid hormone and 1,25-dihydroxyvitamin D(3). Bone mineral density (BMD) did not vary significantly; however, a trend toward an increase in head BMD and a decrease in trunk, lumbar vertebrae and lower limb BMD was observed. A decrease in the lower limb lean content occurred by day 27 and was maximum by day 42 after the beginning of bedrest; it normalized by day 30 after bedrest. The serum levels of both osteocalcin and C-terminal crosslinked telopeptide of type I collagen increased as a consequence of bedrest. A slight increase in the serum levels of the N-terminal propeptide of type III collagen, a marker of connective tissue metabolism, was observed during the bedrest period. Except for the C-terminal extension propeptide of type I collagen, all markers decreased to baseline pre-immobilization levels during the 1-month recovery phase. Serum PTH and 1,25-dihydroxyvitamin D(3) levels were low during the bedrest period and rose during the reambulation phase. These results seem to reflect early changes in bone and connective tissue metabolism as a result of bedrest unloading, but their order of magnitude remains moderate, thus emphasizing the necessity to perform longer-duration trials.