Mouse models of tumor development in neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is a prevalent familial cancer syndrome resulting from germ line mutations in the NF1 tumor suppressor gene. Hallmark features of the disease are the development of benign peripheral nerve sheath tumors (neurofibromas), which can progress to malignancy. Unlike humans, mice that are heterozygous for a mutation in Nf1 do not develop neurofibromas. However, as described here, chimeric mice composed in part of Nf1-/- cells do, which demonstrates that loss of the wild-type Nf1 allele is rate-limiting in tumor formation. In addition, mice that carry linked germ line mutations in Nf1 and p53 develop malignant peripheral nerve sheath tumors (MPNSTs), which supports a cooperative and causal role for p53 mutations in MPNST development. These two mouse models provide the means to address fundamental aspects of disease development and to test therapeutic strategies.

Analysis of changes in acute-phase plasma proteins in an acute inflammatory response and in rheumatoid arthritis using two-dimensional gel electrophoresis

Two-dimensional (2-D) gel analysis was used to examine differences in the levels of 19 plasma proteins: before and after an acute inflammatory reaction (parenteral typhoid vaccination) in normal subjects, between rheumatoid arthritis (RA) patients and normals and in RA patients treated with tenidap (120 mg) and piroxicam (20 mg). Typhoid vaccination increased levels of SAA, haptoglobin alpha1, haptoglobin alpha2, haptoglobin beta and alpha1-anti-chymotrypsin but decreased transthyretin and apolipoprotein E. In RA patients, serum amyloid A (SAA), haptoglobin alpha2, haptoglobin beta, alpha1-antichymotrypsin and C3 proactivator levels were elevated while apolipoprotein A-I, apolipoprotein A-IV, transthyretin, Gc-globulin, alpha2-HS glycoprotein, alpha2-macroglobulin and alpha1-B glycoprotein levels were decreased, compared to normals. Compared to piroxicam, tenidap lowered levels of alpha1-antiprotease and SAA but raised the levels of transthyretin, Gc-globulin, alpha2-HS-glycoprotein and alpha2-macroglobulin in RA patients. C-reactive protein (CRP) could not be quantified on 2-D gels but, when measured by rate nephelometry, levels were reduced after treatment with tenidap compared to piroxicam. The general pattern of the acute phase protein response to an acute inflammatory response to typhoid vaccination is similar to that in the chronic inflammatory condition, RA. The impact of tenidap on both positive and negative acute-phase proteins in RA patients could clearly be distinguished from that of piroxicam.

A biophysical study of integral membrane protein folding

In order to characterize the thermodynamic constraints on the process of integral membrane protein folding and assembly, we have conducted a biophysical dissection of the structure of bacteriorhodopsin (BR), a prototypical alpha-helical integral membrane protein. Seven polypeptides were synthesized, corresponding to each of the seven transmembrane alpha-helices in BR, and the structure of each individual polypeptide was characterized in reconstituted phospholipid vesicles. Five of the seven polypeptides form stable transmembrane alpha-helices in isolation from the remainder of the tertiary structure of BR. However, using our reconstitution protocols, the polypeptide corresponding to the F helix in BR does not form any stable secondary structure in reconstituted vesicles, and the polypeptide corresponding to the G helix forms a hyperstable beta-sheet structure with its strands oriented perpendicular to the plane of the membrane. [The polypeptide corresponding to the C helix spontaneously equilibrates in a pH-dependent manner between a transmembrane alpha-helical conformation, a peripherally bound nonhelical conformation, and a fully water soluble conformation; the conformational properties of this polypeptide are the subject of the accompanying paper: Hunt et al. (1997) Biochemistry 36, 15177-15192.] Our observations suggest that the folding of alpha-helical integral membrane proteins may proceed spontaneously. However, the preference for a non-native conformation exhibited by two of the polypeptides suggests that the formation of some transmembrane substructures could require external constraints such as the links between the helices, interactions with the rest of the protein, or the involvement of cellular chaperones or translocases. Our results also suggest a strategy for improving the thermodynamic stability of alpha-helical integral membrane proteins, a goal that could facilitate attempts to overexpress and/or refold them.

Lotus corniculatus condensed tannins decrease in vivo populations of proteolytic bacteria and affect nitrogen metabolism in the rumen of sheep

Condensed tannins in forage legumes improve the nutrition of sheep by reducing ruminal degradation of plant protein and increasing crude protein flow to the intestine. However, the effects of condensed tannins in forage legumes on rumen bacterial populations in vivo are poorly understood. The aim of this study was to investigate the specific effects of condensed tannins from Lotus corniculatus on four proteolytic rumen bacteria in sheep during and after transition from a ryegrass (Lolium perenne)-white clover (Trifolium repens) diet (i.e., low condensed tannins) to a Lotus corniculatus diet (i.e., higher condensed tannins). The bacterial populations were quantified using a competitive polymerase chain reaction. Lotus corniculatus was fed with or without ruminal infusions of polyethylene glycol (PEG), which binds to and inactivates condensed tannins, enabling the effect of condensed tannins on bacterial populations to be examined. When sheep fed on ryegrass-white clover, populations of Clostridium proteoclasticum B316T, Butyrivibrio fibrisolvens C211a, Eubacterium sp. C12b, and Streptococcus bovis B315 were 1.5 x 10(8), 1.1 x 10(6), 4.6 x 10(8), and 7.1 x 10(6) mL(-1), respectively. When the diet was changed to Lotus corniculatus, the average populations (after 8-120 h) of C. proteoclasticum, B. fibrisolvens, Eubacterium sp., and S. bovis decreased (P < 0.001) to 2.4 x 10(7), 1.1 x 10(5), 1.1 x 10(8), and 2.5 x 10(5) mL(-1), respectively. When PEG was infused into the rumen of sheep fed Lotus corniculatus, the populations of C. proteoclasticum, B. fibrisolvens, Eubacterium sp., and S. bovis were higher (P < 0.01-0.001) than in sheep fed Lotus corniculatus without the PEG infusion, with average populations (after 8-120 h) of 4.9 x 10(7), 3.8 x 10(5), 1.9 x 10(8), and 1.0 x 10(6), respectively. Sheep fed the Lotus corniculatus diet had lower rumen proteinase activity, ammonia, and soluble nitrogen (P < 0.05-0.001) than sheep that were fed Lotus corniculatus plus PEG. The Lotus corniculatus diet reduced rumen nitrogen digestibility (P < 0.05) and ammonia pool size and increased the flow of undegraded feed nitrogen to the abomasum. The nitrogen intake, rumen non-ammonia nitrogen pool size, rumen microbial non-ammonia nitrogen pool size, and abomasal microbial non-ammonia nitrogen fluxes were similar both in sheep fed only Lotus corniculatus and in sheep fed Lotus corniculatus plus PEG, but nonmicrobial non-ammonia nitrogen flux to the abomasum was higher (P < 0.01) for the sheep fed only Lotus corniculatus. Although condensed tannins in Lotus corniculatus reduced the populations of some proteolytic bacteria, total ruminal microbial protein and microbial protein outflow to the abomasum were unchanged, suggesting a species-specific effect of condensed tannins on bacteria in the rumen.

An elective-titration study of the comparative effectiveness of two angiotensin II-receptor blockers, irbesartan and losartan. Irbesartan/Losartan Study Investigators

This multicenter, randomized, double-masked, elective-titration study was designed to compare the effectiveness, safety, and tolerability of irbesartan and losartan, two angiotensin II subtype AT1-receptor blockers, in the treatment of patients with mild-to-moderate hypertension. After a 3-week, single-masked, placebo lead-in period, 432 patients with a mean seated diastolic blood pressure (SeDBP) of 95 to 115 mm Hg were randomly allocated to receive either irbesartan 150 mg once daily (n = 213) or losartan 50 mg once daily (n = 219). At week 4, if SeDBP at trough (i.e., 24 +/- 3 hours after the previous dose) was > or = 90 mm Hg, the daily dose was doubled (to irbesartan 300 mg or losartan 100 mg). At week 8, if trough SeDBP was > or = 90 mm Hg, hydrochlorothiazide 12.5 mg once daily was added to the regimen; consistent with the prescribing information for losartan, the dose of losartan was reduced to 50 mg once daily on the addition of hydrochlorothiazide. A total of 370 patients (178 irbesartan and 192 losartan) were evaluable for efficacy. The mean change in trough SeDBP at week 8, the primary efficacy end point, was significantly greater in patients receiving irbesartan monotherapy than in those receiving losartan monotherapy (-10.2 mm Hg vs -7.9 mm Hg, respectively). At week 12, reductions in trough SeDBP and seated systolic blood pressure were greater with irbesartan treatment than with losartan treatment (-13.8 mm Hg vs -10.8 mm Hg and -18.0 mm Hg vs -13.9 mm Hg, respectively), and a greater proportion of irbesartan patients responded to therapy (i.e., trough SeDBP < 90 mm Hg or reduction in trough SeDBP > or = 10 mm Hg) compared with losartan patients (78% vs 64%, respectively). Both regimens were well tolerated.

Detection of Clostridium proteoclasticum and closely related strains in the rumen by competitive PCR

A competitive PCR technique was used to enumerate the proteolytic bacterium Clostridium proteoclasticum from the rumen. A PCR primer, which circumscribes this organism and several closely related strains, was designed for a variable region within their 16S rRNA genes and was used in conjunction with a universal forward primer. This primer pair was tested for specificity against 85 ruminal bacterial strains. An internal control DNA was constructed for use in competitive PCRs and was shown to amplify under the same reaction conditions and with the same amplification efficiency as the target DNA. DNA from a known number of C. proteoclasticum cells was coamplified with the internal control to construct a standard curve. Rumen samples were collected from eight dairy cows fed four diets in rotation: high nitrogen, high nitrogen supplemented with carbohydrate, low nitrogen, and low nitrogen supplemented with carbohydrate. DNA extracted from these and spiked with internal control DNA was amplified with the C. proteoclasticum primer pair. The relative intensities of the PCR products were used to quantitate the numbers of C. proteoclasticum cell equivalents from the rumen samples. The numbers ranged from 2.01 x 10(6) ml-1 to 3.12 x 10(7) ml-1. There was no significant effect on the numbers of C. proteoclasticum detected in rumen samples among cows fed the four diets. The utility of the competitive PCR approach for quantifying ruminal bacterial populations in vivo and the occurrence of C. proteoclasticum in forage-fed dairy cows are discussed.

Efficacy of intravenously administered theophylline in children hospitalized with severe asthma

PURPOSE

To determine whether intravenously administered theophylline, when added to frequently nebulized albuterol and intravenously administered methylprednisolone, benefits children hospitalized with severe asthma.

DESIGN

Prospective, randomized, placebo-controlled, parallel-group, double-blind study.

SETTING

Inpatient pediatric service at a tertiary-care teaching hospital.

PATIENTS

Twenty-one children 5 to 18 years of age.

INTERVENTIONS

All patients received 2.5 to 5.0 mg of nebulized albuterol every 20 minutes to every 6 hours, intravenously administered methylprednisolone (1 mg/kg every 6 hours), and either intravenously administered theophylline (as aminophylline) or placebo for 36 hours. Serum theophylline concentrations were maintained between 55 and 110 mumol/L (between 10 and 20 micrograms/ml) by adjusting loading doses and continuous infusion rates.

MEASUREMENTS AND MAIN RESULTS

Forced expired volume in 1 second (FEV1) and clinical score were measured at 0, 1, 3, 6, 12, 24, and 36 hours after the start of each individual study. The total number of nebulizations, total albuterol dosage, adverse effects, and duration of hospital stay were recorded. Twelve children received theophylline and nine received placebo. The two groups did not differ significantly in age, sex, or baseline FEV1. In both groups, clinical score significantly improved from baseline by 12 hours, and FEV1 by 24 hours (p < 0.05). There were no significant differences between the groups in FEV1 or clinical score at any of the measured time points. There were no significant differences in rate of improvement in FEV1, total number of nebulizations, total albuterol dosage, or duration of hospital stay. Adverse effects were mild and infrequent and did not differ significantly between the two groups.

CONCLUSIONS

Theophylline, at therapeutic concentrations, did not additionally benefit children hospitalized with severe asthma who were being treated frequently with nebulized albuterol and with methylprednisolone intravenously.

Autoradiographic localization of (125)i[Tyr(14)] nociceptin/orphanin FQ binding sites in macaque primate CNS

Nociceptin/orphanin FQ (N/OFQ) is a recently identified neuropeptide that has been implicated in a multitude of CNS functions. These include nociception, feeding, cognition, locomotion, stress and neuroendocrine control. The endogenous receptor for this ligand is the nociceptin/orphanin FQ peptide (NOP) receptor. The distribution of NOP in rodent has been widely reported by the use of in situ hybridization, immunohistochemistry and autoradiographic radioligand binding but less is known of its localization in higher species. We have therefore sought to optimize and determine the distribution of (125)I[Tyr(14)]N/OFQ binding sites in macaque primate brain and spinal cord. Highest levels of binding were observed in neocortical areas, hippocampus, amygdala, caudate nucleus and putamen, medial thalamic nuclei and superficial laminae of the superior colliculus. These novel data present for the first time, the distribution of N/OFQ receptors in non-human primate CNS and, by comparison with localization in the rat, reveal that species differences may exist in the distribution of this neuropeptide receptor. These data have important implications regarding the roles of N/OFQ across species and may have ramifications in the interpretation of preclinical pharmacological studies.

Differences between a supervised and independent strength and conditioning program with chronic low back syndromes

The purpose of this study was to evaluate changes in physiologic parameters seen in a group of patients with chronic low back syndrome assigned to supervised and independent strength and conditioning programs. Forty patients with chronic low back syndrome were assigned either to a control group (independent exercise) or to an experimental group (supervised exercise). All subjects underwent pre-testing for aerobic fitness, strength and responses to visual analog pain rating scales. Twenty control subjects were given predesigned exercise programs and told to exercise four times per week for 6 months. Twenty experimental subjects were given predesigned exercise programs but were monitored by a strength and conditioning specialist for the same period. Statistically significant results were seen for increases in aerobic fitness and strength, decreases in reported pain, and percent body fat in the experimental group. Since the experimental group completed 90.75 sessions out of 96, compared with 31.95 for the control group, it could be concluded that supervision increases chances for compliance and success as measured by these parameters.

A controlled clinical trial for stuttering in persons aged 9 to 14 years

This paper presents the results of a controlled trial of child stuttering treatment. The aim of the study was, first, to compare the effectiveness of three viable treatments, and, second, to compare these three treatments to a no-treatment control composed of children who stuttered of a similar age and sex ratio who were on treatment waiting lists. The three treatments investigated included intensive smooth speech, intensive electromyography feedback, and home-based smooth speech. The children/adolescents were assessed across three speaking contexts on measures of percentage syllables stuttered (% SS) and syllables spoken per minute (SPM) and outcomes were assessed 12 months later. Repeated measures analyses of variance demonstrated significant differences between the control group and all three treatment groups across time on conversations in the clinic, on the telephone, and at home (although home measures were not taken for the intensive smooth speech group). Although the controls' stuttering did not change across time, the treatment groups' stuttering was decreased to very low levels posttreatment (less than 1% syllables stuttered on average), with mean improvement in stuttering frequency of at least 85% to 90% across all assessment contexts. Stuttering did not increase significantly up to 3 months and one year posttreatment in the experimental groups, although levels did rise across time (less than 3% syllables stuttered on average). Speech naturalness results showed increasing naturalness across time as rated by the clinician and parent. This was not the case for the controls. The children were also less anxious across time following treatment. The results suggest that all three treatments for children aged 9-14 who stutter were very successful in the long term for over 70% of the group, though the EMG feedback and home-based treatments were superior when percentages falling below a cutoff point (2%SS) were used to discriminate between groups. Implications for child/adolescent treatment in the community are discussed. Long-term outcomes will be assessed up to 5 years after the treatment.

The role of foot and ankle assessment of patients with lower limb osteoarthritis

OBJECTIVES

Physiotherapists do not routinely examine the feet of patients with lower limb osteoarthritis, and there is no widely used tool for measuring foot posture. However, differences in foot posture have been demonstrated between patients with medial compartment osteoarthritis of the knee and osteoarthritis of the hip, and guidelines for managing these patients include interventions such as orthotics which presume foot assessment. This study considers a new clinical tool, the Foot Posture Index (FPI). It examines its utility in a physiotherapy outpatient setting with a cohort of patients with medial compartment osteoarthritis of the knee and osteoarthritis of the hip, and investigates the relationship of FPI scores with the range of dorsiflexion of the ankle.

DESIGN

Cross-sectional observational study.

SETTING

A specialist orthopaedic hospital.

PARTICIPANTS

In total, there were 60 participants: 20 patients with medial compartment osteoarthritis of the knee, 20 patients with osteoarthritis of the hip, and a control group of 20 age-matched healthy volunteers.

OUTCOME MEASURES

A single measurement of the FPI and range of dorsiflexion.

RESULTS

Significant differences in FPI scores and range of dorsiflexion were seen between groups. On average, patients with osteoarthritis of the hip had more supinated, plantarflexed feet, and patients with medial compartment osteoarthritis of the knee had pronated feet. Healthy controls fell within the normal range. Patients with osteoarthritis of the hip had a median FPI score of -4.5, patients with medial compartment osteoarthritis of the knee had a median FPI score of 7.0, and the healthy controls had a median FPI score of 1.0. The median difference in FPI scores between patients with osteoarthritis of the hip and medial compartment osteoarthritis of the knee was 12 [95% confidence interval (CI) 10 to 13]; between patients with osteoarthritis of the hip and the healthy group was 6 (95% CI 3 to 9); and between patients with medial compartment osteoarthritis of the knee and the healthy group was 5 (95% CI 3 to 8). The median difference in dorsiflexion scores between patients with osteoarthritis of the hip and medial compartment osteoarthritis of the knee was 10 degrees (95% CI 8 to 15); between patients with osteoarthritis of the hip and the healthy group was 10 degrees (95% CI 7 to 15); and between patients with medial compartment osteoarthritis of the knee and the healthy group was 0 degrees (95% CI -3 to 5). Foot posture and range of dorsiflexion were moderately positively correlated (rho 0.57), with pronated feet having a greater range of dorsiflexion.

CONCLUSION

The FPI is sufficiently sensitive to measure differences in foot posture of patients with medial compartment osteoarthritis of the knee and osteoarthritis of the hip, and is easy to use. Accurate foot assessment is useful as foot postures may be influenced by specific physiotherapy treatment modalities and orthotic interventions.

Clostridium proteoclasticum sp. nov., a novel proteolytic bacterium from the bovine rumen

A novel proteolytic bacterium was isolated from rumen contents of New Zealand cattle grazing fresh forage and was designated strain B316(T) (T = type strain). Strain B316(T) cells were straight to slightly curved rods (width, 0.4 to 0.6 microns; length, 1.3 to 3.0 microns) that were gram-positive and possessed a single subterminal flagellum. This isolate did not produce catalase, indole, ammonia, lipase, or lecithinase, or reduce nitrate, but it did produce a curd reaction with milk. Strain B316(T) was proteolytic, hydrolyzing casein and fraction I leaf protein. The crude proteinase was predominantly the serine type, but some cysteine proteinase and metallo-proteinase activities were also detected. The DNA base composition of strain B316(T) was 28 mol% G+C. A 16S ribosomal DNA sequence analysis of strain B316(T) indicated that it was most closely related to a member of clostridial cluster XIVa, viz., Clostridium aminophilum, an amino acid-fermenting organism isolated from the rumen; the similarity value was 92.2%. The results of the phenotypic characterization analysis, G+C content analysis, and phylogenetic analysis of the 16S ribosomal DNA sequence set strain B316(T) apart from all of the members of cluster XIVa. We propose that strain B316(T) should be designated a new species of the genus Clostridium, Clostridium proteoclasticum. Strain B316 is the type strain and has been deposited in the American Type Culture Collection as strain ATCC 51982.

Identification of proteolytic rumen bacteria isolated from New Zealand cattle

The protease activities of 212 strains of rumen bacteria isolated from New Zealand cattle grazing pasture were measured. Thirty-seven per cent of strains had activity greater than or equal to the proteolytic rumen bacterium Prevotella ruminicola and 43 of these isolates were identified by morphology, carbon source utilization, Gram stain, biochemical tests and fermentation end-product analysis. Hierarchical Cluster Analysis showed that the strains formed four clusters: cluster A contained 26 strains and clustered with a reference strain of Streptococcus bovis; cluster C contained three strains and clustered with a reference strain of Butyrivibrio fibrisolvens, while clusters B (10 strains) and D (three strains) did not cluster with any of the remaining rumen bacterial type strains. Further tests identified strains of cluster B as Eubacterium budayi, while cluster D strains most closely resembled B. fibrisolvens and were described as B. fibrisolvens-like. An unclustered strain, C21a, was identified as P. ruminicola. The significance of these proteolytic bacterial populations is discussed in relation to protein breakdown in New Zealand ruminants.

Isolation and characterisation of a cassava catalase expressed during post-harvest physiological deterioration

Storage roots of cassava undergo a rapid, endogenous, post-harvest deterioration response that is thought to involve oxidative processes. A cassava catalase (MecCAT1) was isolated from a root cDNA library. The transcript is expressed predominantly in roots with little expression in leaves. Catalase enzyme activity and MecCAT1 transcript expression during the post-harvest period were compared in highly susceptible and less susceptible cultivars and suggest that high levels of catalase activity may play a role in delaying the deterioration response.

The production of varicella Zoster virus antiserum in laboratory animals. Brief report

Hyperimmune anti-varicella zoster virus (VZV) antisera were prepared in BALB/c mice, Lewis rats and New Zealand rabbits by subcutaneous inoculations of purified VZ virions suspended in Freund's adjuvant. VZV antibodies were demonstrated both by an enzyme-linked immunosorbent assay (ELISA) and by indirect immunofluorescence (IF). VZV could not be detected in organs of any inoculated animals by IF or by cocultivation of tissue fragments from infected animals with human diploid fibroblasts.

Diagnosis and treatment of lower urinary tract symptoms suggestive of overactive bladder and bladder outlet obstruction among men in general practice in the UK

OBJECTIVE

To assess the epidemiology and treatment of storage symptoms suggestive of overactive bladder (OAB) and voiding symptoms suggestive of bladder outlet obstruction (BOO) because of benign prostatic hyperplasia in UK general practice.

PATIENTS AND METHODS

This was a retrospective analysis of data collected between 2000 and 2006 and entered in The Health Improvement Network general practice database, containing medical records for > 1 million men (aged >or= 18 years) in the UK. Using Read codes, we analysed the prevalence of storage and voiding lower urinary tract symptoms (LUTS) as well as prescribing trends for 5alpha-reductase inhibitors (5ARIs) and alpha-blockers for LUTS secondary to BOO and antimuscarinics for OAB.

RESULTS

In 2006, the prevalence of diagnosed LUTS/OAB was only 0.3% and the recorded prevalence of LUTS/BOO was only 2.2%. Treatment rates also remained low throughout the study period. In the 12 months before 1 January 2006, only 25% of men diagnosed with OAB and 6-7% of men with storage LUTS received antimuscarinics, whereas 36% of men with a record of LUTS/BOO received alpha-blockers and/or 5ARIs. Alpha-blockers were prescribed to approximately 10% of men diagnosed with OAB or storage LUTS who did not have any recorded BOO diagnosis or symptoms.

CONCLUSION

Diagnosis of both storage and voiding LUTS occurs at much lower rates than indicated by prevalence estimates. Despite the availability of effective prescription therapies, many men with storage and/or voiding LUTS may not be receiving appropriate treatment in UK general practice.

Seroepidemiologic studies of hantavirus infection among wild rodents in California

A total of 4,626 mammals were serologically tested for antibodies to Sin Nombre virus. All nonrodent species were antibody negative. Among wild rodents, antibody prevalence was 8.5% in murids, 1.4% in heteromyids, and < 0.1% in sciurids. Of 1,921 Peromyscus maniculatus (deer mice), 226 (11.8%) were antibody positive, including one collected in 1975. The highest antibody prevalence (71.4% of 35) was found among P. maniculatus on Santa Cruz Island, off the southern California coast. Prevalence of antibodies among deer mice trapped near sites of human cases (26.8% of 164) was significantly higher than that of mice from other sites (odds ratio = 4.5; 95% confidence interval = 1.7, 11.6). Antibody prevalence increased with rising elevation (> 1,200 meters) and correlated with a spatial cluster of hantavirus pulmonary syndrome cases in the Sierra Nevada.

Bone replaces articular cartilage in the rat knee joint after prolonged immobilization

BACKGROUND

Lost joint range of motion (ROM) is common in chronic osteoarthritis, alters regional weight-bearing across the articular surfaces, and contributes to loss of cartilage and bone alterations. Limited data exist on the regional effects on joints subjected to chronic losses of ROM.

OBJECTIVE

To characterize the regional replacement by bone as part of articular cartilage degeneration after prolonged immobilization.

METHODS

Eleven rat knees were rigidly-immobilized in flexion for 32weeks with contralateral and sham-operated (n=6) knees as controls. Sagittal medial tibial epiphysis histological sections assessed the anterior (non-weight-bearing), middle and posterior (both weight-bearing) regions. We quantified the distribution of collagen I, collagen II, cartilage thickness, glycosaminoglycan (GAG) staining, Mankin scoring, and subchondral bone plate cross-sectional area. Using immunohistochemistry (IHC), we visualized blood vessels, osteoblasts, and mesenchymal stem cells (MSCs).

RESULTS

Immobilized cartilage had increased collagen I content in the anterior tibial region with picrosirius red staining (immobilized=61±20%; contralateral=43±12%, p=0.033; sham=20±10%, p=0.028) and collagen I IHC (immobilized=40±10%; contralateral=11±4%, p=0.003; sham=5±3%, p=0.043). Articular cartilage was thinner anteriorly (18±30μm) in immobilized knees versus contralateral (124±40μm, p<0.001) and sham (125±43μm, p=0.043). GAG staining covered 2±4% of the anterior articular area in immobilized knees versus 28±12% contralaterally (p=0.003) and 26±7% in sham (p=0.043). Mankin scores in immobilized knees were 4.7±1.7 versus 0.2±0.4 and 0±0 for contralateral and sham (p=0.003, p=0.042), respectively. The trabecular bone plate area of anterior and posterior regions showed relative loss of cross-sectional area in immobilized knees compared to controls (immobilized/contralateral area ratios of 0.67 and 0.46 respectively, both p=0.003), while the area in the middle region was preserved. Movat's pentachrome stain and CD31 staining showed chondral vascular ingrowth from subchondral bone. Osteocalcin and CD90 MSC staining were decreased in immobilized knees versus contralateral (p=0.003, p=0.036 respectively).

CONCLUSIONS

Bony replacement characterizes articular cartilage degeneration of knees immobilized for 32weeks in the anterior, non-weight bearing region of the tibia. Replacement of cartilage by bone may have been mediated by chondral vascularization, suggesting irreversible changes. These findings stress the importance of weight-bearing and joint motion to maintain cartilage structure.

Design and use of 16S ribosomal DNA-directed primers in competitive PCRs to enumerate proteolytic bacteria in the rumen

Competitive Polymerase Chain Reaction primers were designed for Streptococcus, B. fibrisolvens, P. bryantii, Eubacterium sp., Prevotella, and a universal primer for the eubacteria. DNA was extracted from rumen contents collected from eight dairy cows fed four diets: adequate nitrogen, adequate nitrogen plus carbohydrate, low nitrogen, and low nitrogen plus carbohydrate. B. fibrisolvens was significantly higher on the adequate nitrogen plus carbohydrate and the low nitrogen plus carbohydrate diets compared with the other diets, while P. bryantii was significantly higher on the low nitrogen plus carbohydrate diet compared with the adequate nitrogen diet. The population of Eubacterium sp. was significantly lower on both the adequate nitrogen plus carbohydrate and low nitrogen plus carbohydrate diets. Streptococcus populations were significantly lower on the low nitrogen plus carbohydrate diet compared with all three other diets, whereas there were no significant differences in populations of Prevotella or total eubacteria on any of the diets.

Integration and Impact of Telemedicine in Underserved Pediatric Primary Care

Telemedicine, more novel in provision of pediatric care, rapidly expanded due to the recent coronavirus disease 2019 pandemic. This study aimed to determine the feasibility of telemedicine for acute and chronic care provision in an underserved pediatric primary care center. Items assessed included patient demographic data, chief complaint, and alternative care locations if telemedicine was not available. In our setting, 62% of telemedicine visits were for acute concerns and 38% for chronic concerns. Of acute telemedicine visits, 16.5% of families would have sought care in the Emergency Department/Urgent Care, and 11.3% would have opted for no care had telemedicine not been offered. The most common chronic issues addressed were attention deficit hyperactivity disorder (80.3%) and asthma (16.9%). Racial disparities existed among our telemedicine visits with Black patients utilizing telemedicine services less frequently than non-Black patients. Telemedicine is feasible for pediatric acute and chronic care, but systems must be designed to mitigate widening racial disparities.

Quantitative computer-assisted osteodensitometry in total hip arthroplasty

Several factors can cause bone loss and fixation failure following total hip arthroplasty (THA), including polyethylene wear debris, implant micromotion and stress shielding. Various techniques have been used in an effort to detect bone density loss in vivo, all with varying success. Quantitative computed tomography (qCT)-assisted osteodensitometry has been shown to be useful in assessing the in vivo structural bone changes after THA. It has a high resolution, accuracy and reproducibility, thereby making it a useful tool for research purposes, and it is able to differentiate between cortical and cancellous bone structures and assess the bone/implant interface. This technique also provides valuable information about the pattern of stress shielding which occurs around the prosthesis and can show early bony changes, which may prove informative about the quality of implant fixation and surrounding bone adaptation. In conjunction with finite-element analysis, qCT is able to generate accurate patient-specific meshes on which to model implants and their effect on bone remodelling. This technology can be useful to predict bone remodelling and the quality of implant fixation using prostheses with different design and/or biomaterials. In the future, this tool could be used for pre-clinical validation of new implants before their introduction in the market-place.

Evolution of the oxygen sensitivity of cytochrome c oxidase subunit 4

Vertebrates possess two paralogs of cytochrome c oxidase (COX) subunit 4: a ubiquitous COX4-1 and a hypoxia-linked COX4-2. Mammalian COX4-2 is thought to have a role in relation to fine-tuning metabolism in low oxygen levels, conferred through both structural differences in the subunit protein structure and regulatory differences in the gene. We sought to elucidate the pervasiveness of this feature across vertebrates. The ratio of COX4-2/4-1 mRNA is generally low in mammals, but this ratio was higher in fish and reptiles, particularly turtles. The COX4-2 gene appeared unresponsive to low oxygen in nonmammalian models (zebrafish, goldfish, tilapia, anoles, and turtles) and fish cell lines. Reporter genes constructed from the amphibian and reptile homologues of the mammalian oxygen-responsive elements and hypoxia-responsive elements did not respond to low oxygen. Unlike the rodent ortholog, the promoter of goldfish COX4-2 did not respond to hypoxia or anoxia. The protein sequences of the COX4-2 peptide showed that the disulfide bridge seen in human and rodent orthologs would be precluded in other mammalian lineages and lower vertebrates, all of which lack the requisite pair of cysteines. The coordinating ligands of the ATP-binding site are largely conserved across mammals and reptiles, but in Xenopus and fish, sequence variations may disrupt the ability of the protein to bind ATP at this site. Collectively, these results suggest that many of the genetic and structural features of COX4-2 that impart responsiveness and benefits in hypoxia may be restricted to the Euarchontoglires lineage that includes primates, lagomorphs, and rodents.

Physical activity and social connectedness interventions in outdoor spaces among children and youth: a rapid review

INTRODUCTION

The rise in sedentary behaviour, coupled with the decline in overall mental health among Canadian children and youth in recent decades, demonstrates a clear need for applied research that focusses on developing and evaluating cross-disciplinary interventions. Outdoor spaces provide opportunities for physical activity and social connectedness, making them an ideal setting to address these critical health concerns among children and youth.

METHODS

We conducted a rapid review of peer-reviewed (n = 3096) and grey literature (n = 7) to identify physical activity and/or social connectedness outdoor space interventions targeted at children and youth (19 years and under) in Australia and New Zealand, Canada, Europe and the United States. We determined if interventions were effective by analyzing their research design, confidence intervals and reported limitations, and then conducted a narrative synthesis of the effective interventions.

RESULTS

We found 104 unique studies, of which 70 (67%) were determined to be effective. Overall, 55 interventions targeted physical activity outcomes, 10 targeted social connectedness outcomes and 5 targeted both. Play (n = 47) and contact with nature (n = 25) were dominant themes across interventions, with most taking place in a school or park. We report on the identifying features, limitations and implications of these interventions.

CONCLUSION

The incorporation of natural and play-focussed elements into outdoor spaces may be effective ways to improve physical activity and social connectedness. There is a considerable need for more Canadian-specific research. Novel methods, such as incorporating smartphone technology into the design and evaluation of these interventions, warrant consideration.

Hydrogen peroxide and flavan-3-ols in storage roots of cassava (Manihot esculenta crantz) during postharvest deterioration

Cassava storage roots are an important staple food throughout the lowland humid tropics. However, cassava suffers from a poorly understood storage disorder, known as postharvest physiological deterioration (PPD), which constrains its exploitation. In an attempt to broaden the understanding of PPD, nine different cassava cultivars were analyzed for specific compounds accumulating during the process. The production of hydrogen peroxide (H(2)O(2)) is involved in the early stages of PPD in cassava roots. H(2)O(2) was quantified and localized histochemically at the tissue and cell level in deteriorating roots. This reactive oxygen species accumulated during the first 24 h after harvest, especially in the inner parenchymatic tissue. Three flavan-3-ols, (+)-catechin, (+)-catechin gallate, and (+)-gallocatechin, accumulated during the storage of cassava roots. However, these potential antioxidants cannot be related to early storage disorders or wound responses because they start to accumulate only after 4-6 days.