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1.
Mucosal Immunol ; 13(3): 559, 2020 05.
Article in English | MEDLINE | ID: mdl-32005924

ABSTRACT

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

2.
Mucosal Immunol ; 13(2): 205-215, 2020 03.
Article in English | MEDLINE | ID: mdl-31907364

ABSTRACT

The intestinal microbiota plays important roles in human health. This last decade, the viral fraction of the intestinal microbiota, composed essentially of phages that infect bacteria, received increasing attention. Numerous novel phage families have been discovered in parallel with the development of viral metagenomics. However, since the discovery of intestinal phages by d'Hérelle in 1917, our understanding of the impact of phages on gut microbiota structure remains scarce. Changes in viral community composition have been observed in several diseases. However, whether these changes reflect a direct involvement of phages in diseases etiology or simply result from modifications in bacterial composition is currently unknown. Here we present an overview of the current knowledge in intestinal phages, their identity, lifestyles, and their possible effects on the gut microbiota. We also gather the main data on phage interactions with the immune system, with a particular emphasis on recent findings.


Subject(s)
Bacteriophages , Gastrointestinal Microbiome/immunology , Immune System/virology , Intestines/virology , Animals , Humans , Immunity , Intestines/microbiology , Metagenome
3.
Osteoporos Int ; 22(9): 2475-85, 2011 Sep.
Article in English | MEDLINE | ID: mdl-21104232

ABSTRACT

UNLABELLED: We examined the association of serum 25-hydroxyvitamin D [25(OH)D] with indices of bone quality in older men. Positive associations for 25(OH)D and bone mineral density, content, cortical thickness, and axial and polar strength strain indices were observed among Caucasians; however, among men of African descent findings were either null or negative. INTRODUCTION: There are limited data on serum 25(OH)D and bone measures in men of African ancestry. To better understand racial differences in vitamin D status and bone health, a cross-sectional study among 446 Caucasian men in the US and 496 men of African ancestry in Tobago (age ≥ 65 years) was conducted. METHODS: Serum 25(OH)D (liquid chromatography and tandem mass spectrometry) was measured, and peripheral quantitative computed tomography scans were administered. Bone measures estimated included trabecular and cortical volumetric bone mineral density (vBMD), bone mineral content (BMC), bone geometry (cross-sectional area and cortical thickness), and polar and axial strength strain indices (SSIp and SSIx). RESULTS: Men of African ancestry had higher 25(OH)D than Caucasians (34.7 vs. 27.6 ng/ml, p < 0.01). Among Caucasians, 25(OH)D was positively (p trend < 0.05) associated with cortical vBMD, total BMC, cortical thickness, SSIp, and SSIx at the distal radius after adjustment for potential confounders. Similar patterns were observed at the distal tibia. In contrast, in men of African ancestry, there was an inverse association (p trend < 0.05) between 25(OH)D and the cross-sectional area, and SSIx. Race modified (p for interaction < 0.05) the association between 25(OH)D and total BMC, cross-sectional area, SSIp, SSIx, and trabecular vBMD of the radius. In men of African ancestry, there was evidence of a threshold effect (at approximately 18 ng/ml) for 25(OH)D on tibial total BMC and cortical thickness. CONCLUSIONS: More studies are needed to better comprehend these race differences for 25(OH)D and bone density, geometry, and indices of bone strength.


Subject(s)
Bone Density/physiology , Radius , Tibia , Vitamin D/analogs & derivatives , Aged , Black People , Cross-Sectional Studies , Humans , Male , Pennsylvania , Radius/anatomy & histology , Radius/physiology , Tibia/anatomy & histology , Tibia/physiology , Trinidad and Tobago/ethnology , Vitamin D/blood , White People
4.
J Musculoskelet Neuronal Interact ; 10(2): 128-35, 2010 Jun.
Article in English | MEDLINE | ID: mdl-20516629

ABSTRACT

Harold Frost first proposed the existence of several mechanical thresholds in bone, two of which determine whether bone is added to, or lost from, the skeleton. Recent evidence from bone biology helps elucidate the role of osteocytes in determining these mechanical thresholds. Specifically, when mechanical stimuli fall below the resorption threshold, osteocyte apoptosis occurs, followed by bone resorption. Conversely, mechanical loading maintains osteocytes viability, and consequently, no bone is lost. With a greater than customary mechanical stimulus, osteocytes perturbation from pulsatile fluid flow results in release of anabolic factors and subsequent bone formation. Osteocytes also play a pivotal role in bone remodeling in response to alterations in the mechanical environment. In particular, osteocyte apoptosis results in bone turnover in disuse as well as in response to greater than customary mechanical stimuli due to microdamage accumulation. Given the important role of osteocytes in bone modeling and remodeling, these cells provide an ideal target for both drug therapies and exercise to prevent bone fragility.


Subject(s)
Bone Remodeling/physiology , Osteocytes/physiology , Animals , Apoptosis/physiology , Homeostasis/physiology , Humans , Stress, Mechanical , Weight-Bearing/physiology
5.
Osteoporos Int ; 21(4): 609-17, 2010 Apr.
Article in English | MEDLINE | ID: mdl-19575140

ABSTRACT

UNLABELLED: The growing skeleton is particularly responsive to exercise around the time of puberty, suggesting a possible role for estrogen in mechanical adaptation in young women. We assessed femoral neck strength index at age 17 in young women with varying adolescent physical activity levels and E2 levels in the first 3 years after menarche. The results indicate that both E2 levels in the first year after menarche and adolescent physical activity are positively associated with bone strength in young adulthood, such that hormone levels may modify human osteogenic responses to exercise. INTRODUCTION: It is well established that physical activity contributes to bone strength in young females, but less is known about how peripubertal estrogen affects skeletal responses to exercise. METHODS: We used data from 84 participants in the Penn State Young Women's Health Study to test the prediction that young women who (1) had higher E2 levels during the first year after menarche or (2) were more physically active in adolescence will have greater bone strength at the end of adolescence. Subjects were divided into tertiles of physical activity and of E2 level in the first, second, and third postmenarchal years, and femoral strength was calculated from dual-energy X-ray absorptiometry scans of the proximal femur using hip structure analysis. RESULTS: At age 17, subjects with the highest E2 levels in year 1 after menarche had 5-14% greater strength in the narrow neck and intertrochanteric region, and the most active subjects had 10-11% greater strength in the femoral narrow neck vs. less active girls. CONCLUSIONS: This study suggests that both physical activity and peripubertal estrogen have important influences on young adult bone strength and that hormone levels may be mediators of human osteogenic responses to exercise.


Subject(s)
Estradiol/urine , Femur Neck/physiology , Motor Activity/physiology , Puberty/physiology , Adolescent , Calcium/urine , Estradiol/physiology , Female , Femur Neck/growth & development , Humans , Longitudinal Studies , Menarche/physiology , Vitamin D/administration & dosage , Vitamins/administration & dosage
6.
Bone ; 44(5): 970-5, 2009 May.
Article in English | MEDLINE | ID: mdl-19442622

ABSTRACT

PURPOSE: Ethnic differences in bone strength and structure likely contribute to the disparity in fracture rates, however few studies have assessed bone structure in multiethnic cohorts of children. The purpose of this study was to investigate ethnic differences in bone strength in childhood and to characterize the structural bases for these differences. METHODS: Peripheral quantitative computed tomography (pQCT 3000, Orthometrix) was used to assess bone parameters at the radius and tibia in Caucasian (CA, n=21), African American (AA, n=23), and Hispanic (HI, n=29) children (10.9+/-0.1 yrs). At the distal site (8%), we measured compressive bone strength (BSI), trabecular and total bone density, and total bone area. Polar strength-strain index, total and cortical bone area, and cortical density were assessed at the midshaft (50%). Muscle cross-sectional area (CSA) and fat CSA were measured at the tibia (66%) and the radius (50%). Physical activity and calcium intake were assessed by questionnaire. Analysis of covariance was used to compare bone outcomes among ethnic groups adjusting for age, sex, limb length and muscle CSA. RESULTS: Age, BMI, and body composition were similar among the 3 groups, however AA children were taller and had longer bone length. At all sites, AA and HI children had higher bone strength (SSIp and BSI +10-37%) than CA children due mainly to greater bone tissue density (2-18%>CA) at the distal sites of the radius and tibia. The greater bone strength at the midshaft was due to both a higher bone density (2-5%) and greater bone area than CA (7-18%). CONCLUSION: AA and HI children have significantly higher bone strength than CA children, due to greater bone volumetric density and greater cortical area. AA and HI children also have higher bone strength relative to load. These observations suggest that ethnic differences in bone strength manifest in childhood.


Subject(s)
Bone and Bones/anatomy & histology , Bone and Bones/physiology , Ethnicity , Anthropometry , Body Composition , Body Height , Body Mass Index , Bone and Bones/metabolism , Child , Female , Humans , Male , Radius/anatomy & histology , Radius/metabolism , Radius/physiology , Surveys and Questionnaires , Tibia/anatomy & histology , Tibia/metabolism , Tibia/physiology
7.
Osteoporos Int ; 19(10): 1445-56, 2008 Oct.
Article in English | MEDLINE | ID: mdl-18357403

ABSTRACT

UNLABELLED: The effects of physical activity on bone strength acquisition during growth are not well understood. In our cluster randomized trial, we found that participation in a novel school-based physical activity program enhanced bone strength acquisition and bone mass accrual by 2-5% at the femoral neck in girls; however, these benefits depended on teacher compliance with intervention delivery. Our intervention also enhanced bone mass accrual by 2-4% at the lumbar spine and total body in boys. INTRODUCTION: We investigated the effects of a novel school-based physical activity program on femoral neck (FN) bone strength and mass in children aged 9-11 yrs. METHODS: We used hip structure analysis to compare 16-month changes in FN bone strength, geometry and bone mineral content (BMC) between 293 children who participated in Action Schools! BC (AS! BC) and 117 controls. We assessed proximal femur (PF), lumbar spine (LS) and total body (TB) BMC using DXA. We compared change in bone outcomes between groups using linear regression accounting for the random school effect and select covariates. RESULTS: Change in FN strength (section modulus, Z), cross-sectional area (CSA), subperiosteal width and BMC was similar between control and intervention boys, but intervention boys had greater gains in BMC at the LS (+2.7%, p = 0.05) and TB (+1.7%, p = 0.03) than controls. For girls, change in FN-Z tended to be greater (+3.5%, p = 0.1) for intervention girls than controls. The difference in change increased to 5.4% (p = 0.05) in a per-protocol analysis that included girls whose teachers reported 80% compliance. CONCLUSION: AS! BC benefits bone strength and mass in school-aged children; however, our findings highlight the importance of accounting for teacher compliance in classroom-based physical activity interventions.


Subject(s)
Femur Neck/physiology , Models, Biological , Motor Activity/physiology , Puberty/physiology , Absorptiometry, Photon , Anthropometry/methods , Bone Density/physiology , Child , Exercise/physiology , Female , Humans , Lumbar Vertebrae/physiology , Male , Schools , Sex Factors
8.
Pathol Biol (Paris) ; 55(3-4): 208-10, 2007.
Article in French | MEDLINE | ID: mdl-17412523

ABSTRACT

Circadian clock genes have been identified in humans but information regarding their expression has remained very limited. However from a basic point as well as in a diagnostic and therapeutic perspective, it is important to evaluate molecular clock gene expression. Peripheral blood mononuclear cells represent an ideal material to investigate non-invasively the human clock at the molecular level. Several studies including ours reported rhythmic expression of clock genes in these cells, with significant intersubject variability of expression. In addition, our results reveal the existence of different chronotypes of clock gene expression patterns and suggest specific regulatory mechanisms in these human cells as compared to other peripheral tissues.


Subject(s)
Biological Clocks/genetics , Circadian Rhythm/genetics , Gene Expression Regulation , Leukocytes, Mononuclear/physiology , ARNTL Transcription Factors , Basic Helix-Loop-Helix Transcription Factors/genetics , Cell Cycle Proteins/genetics , Humans , Nuclear Proteins/genetics , Period Circadian Proteins , Transcription Factors/genetics
9.
Osteoporos Int ; 18(6): 797-804, 2007 Jun.
Article in English | MEDLINE | ID: mdl-17205221

ABSTRACT

INTRODUCTION: Better characterization of bone geometry in adolescents with anorexia nervosa (AN) may improve understanding of skeletal deficits in this population. Our objective was to determine whether hip cross-sectional geometry and bone strength were altered in adolescents with AN. METHODS: Measurements of the left total proximal femur and body composition were obtained in 85 adolescents with AN and 61 healthy controls by dual X-ray absorptiometry. The Hip Structural Analysis (HSA) program was used to determine aBMD, cross-sectional area (CSA), and section modulus (Z) at the femoral neck and shaft. Strength indices were calculated and corrected for lean mass. RESULTS: Femoral neck and shaft aBMD were lower in AN patients than healthy controls (-36% and -29%, p < 0.001). In both regions, bone CSA and Z were lower in AN sufferers (-11 to -35%, p < 0.001). While lean body mass correlated with HSA variables (r = 0.48 to 0.58, p < 0.001), body fat did not. AN sufferers had lower indices of both whole bone strength (-40%, p < 0.001) and relative bone strength (-36%, p < 0.001) than controls. CONCLUSIONS: Anorexia nervosa sufferers had decreased resistance to axial (CSA) and bending loads (Z) compared with healthy controls. Differences in strength properties were significant even when adjusted for lean mass, suggesting that not only decreased mechanical loading, but also known metabolic differences are likely responsible for deficits in bone strength in these patients.


Subject(s)
Anorexia Nervosa/pathology , Femur/pathology , Absorptiometry, Photon , Adolescent , Adult , Anorexia Nervosa/physiopathology , Anthropometry/methods , Biomechanical Phenomena , Body Composition , Bone Density , Female , Femur/physiopathology , Femur Neck/pathology , Femur Neck/physiopathology , Humans , Weight-Bearing
10.
Article in English | MEDLINE | ID: mdl-16172512

ABSTRACT

The clinical tools available to evaluate bone development in children are often ambiguous, and difficult to interpret. Unfortunately bone densitometry methods (i.e., dual energy X-ray absorptiometry, DXA) which have a relatively straightforward application in adult osteoporosis, are far more difficult to evaluate in the growing skeleton. Even with adequate "adjustment" for bone size or maturity, bone "density" (areal or volumetric) alone often gives an inaccurate assessment of bone strength--especially in children. Ideally, we would like to measure both material and geometric properties of bone to accurately estimate "strength". Mechanically meaningful measures of bone geometry (bone cross-sectional area, cortical thickness) and estimates of bending strength (section modulus, or SSI) are available with non-invasive techniques such as (p)QCT and some DXA software. With new technology it might be possible to also measure bone material properties, which will be especially important in some pediatric disorders. In children, we also need to know something about the loads imposed on a child's bone and consider not only absolute bone strength, but also the strength of bone relative to the physiologic loads. Interpreting bone strength in light of the loads imposed (particularly muscle force) is critical for an accurate diagnosis of the developing bone.


Subject(s)
Aging/physiology , Anthropometry/methods , Bone Density/physiology , Bone Development/physiology , Bone and Bones/physiology , Bone and Bones/anatomy & histology , Calcification, Physiologic/physiology , Child , Humans , Software , Stress, Mechanical , Weight-Bearing/physiology
11.
BMC Bioinformatics ; 6: 171, 2005 Jul 12.
Article in English | MEDLINE | ID: mdl-16011797

ABSTRACT

BACKGROUND: Public databases now contain multitude of complete bacterial genomes, including several genomes of the same species. The available data offers new opportunities to address questions about bacterial genome evolution, a task that requires reliable fine comparison data of closely related genomes. Recent analyses have shown, using pairwise whole genome alignments, that it is possible to segment bacterial genomes into a common conserved backbone and strain-specific sequences called loops. RESULTS: Here, we generalize this approach and propose a strategy that allows systematic and non-biased genome segmentation based on multiple genome alignments. Segmentation analyses, as applied to 13 different bacterial species, confirmed the feasibility of our approach to discern the 'mosaic' organization of bacterial genomes. Segmentation results are available through a Web interface permitting functional analysis, extraction and visualization of the backbone/loops structure of documented genomes. To illustrate the potential of this approach, we performed a precise analysis of the mosaic organization of three E. coli strains and functional characterization of the loops. CONCLUSION: The segmentation results including the backbone/loops structure of 13 bacterial species genomes are new and available for use by the scientific community at the URL: http://genome.jouy.inra.fr/mosaic.


Subject(s)
Bacteria/classification , Bacteria/genetics , Genome, Bacterial/genetics , Agrobacterium tumefaciens/classification , Bacillus cereus/classification , Chlamydophila pneumoniae/classification , Chromosome Mapping/instrumentation , Conserved Sequence , Databases, Genetic , Escherichia coli/classification , Evolution, Molecular , Information Systems/organization & administration , Internet , Sequence Alignment , Species Specificity
12.
Pathol Biol (Paris) ; 53(5): 261-4, 2005 Jun.
Article in French | MEDLINE | ID: mdl-15939134

ABSTRACT

Dihydropyrimidine deshydrogenase (DPD) is the rate limiting enzyme of 5-fluorouracil (5-FU) catabolism and its activity is generally determined in peripheral blood mononuclear cells. Several studies have highlighted interactions between toxicities to 5-FU and a DPD activity deficiency. Circadian variations in 5-FU anabolism enzymes are suggested. Circadian variations in 5-FU catabolism enzymes, and especially for DPD in healthy subjects or patients, have shown in some cases circadian variations in DPD activity but with different peak times. Based on this knowledge, chronomodulated therapy for the association 5-FU-folinic acid with maximal delivery rate in the first half of the night was shown clearly to be 5 times less toxic than control flat therapy. Nevertheless, in the most active chronotherapy pattern, 30% of the patients have also toxicities. However the timing of the individual peak of DPD activity remains controversial.


Subject(s)
Circadian Rhythm , Dihydrouracil Dehydrogenase (NADP)/metabolism , Fluorouracil/pharmacokinetics , Biotransformation , Humans , Kinetics , Leukocytes, Mononuclear/enzymology
13.
Int J Sports Med ; 25(7): 496-501, 2004 Oct.
Article in English | MEDLINE | ID: mdl-15459829

ABSTRACT

Resistance exercise has positive effects on bone mass, but little is known about the mechanisms by which this occurs. The purpose of this study was to determine if a single bout of moderate intensity resistance exercise alters biochemical markers of bone cell activity. Indices of bone turnover were measured in nine healthy, untrained men (21.9 +/- 1.2 yrs old), before and following a single 45 minute session of resistance exercise, and during a control trial. A cross-over design was used so that all participants performed both trials in random order. Blood samples were collected immediately before, immediately after, and at 1, 8, 24, and 48 hours post exercise and analyzed for bone-specific alkaline phosphatase (BAP), type I collagen propeptide (PICP), and type I collagen N-telopeptide (sNTX). Urine from the second morning void was collected over four days (day before, day of, and two days following exercise) and analyzed for type I collagen N-telopeptide (uNTX). Exercise resulted in a significant increase (p < 0.05) in the ratio of biochemical markers of bone formation to bone resorption eight hours post exercise, largely due to a decrease in sNTX. Markers return to baseline within 24 hrs. These data suggest that moderate intensity resistance training acutely reduces bone resorption, leading to a favorable change in overall bone turnover, for at least 8 hours post exercise in untrained young men. Further work is needed to determine if long-term benefits to bone strength follow with persistent training.


Subject(s)
Bone Remodeling/physiology , Bone and Bones/cytology , Exercise/physiology , Weight Lifting/physiology , Adult , Biomarkers/blood , Bone Density , Bone and Bones/physiology , Cross-Over Studies , Humans , Male , Weight-Bearing
14.
Br J Sports Med ; 37(4): 315-20, 2003 Aug.
Article in English | MEDLINE | ID: mdl-12893716

ABSTRACT

BACKGROUND: Oral contraceptives are commonly used by women athletes. However, their effect on athletic performance is unclear. OBJECTIVES: To examine the effects of a moderate dose, triphasic oral contraceptive on measures of athletic performance in highly trained women athletes. METHODS: This is a double blind, placebo controlled trial in 14 women with ovulatory menstrual cycles and maximal aerobic capacity (VO(2)MAX) >/==" BORDER="0">50 ml/kg/min. Four measures of athletic performance were tested: VO(2)MAX, anaerobic capacity (anaerobic speed test), aerobic endurance (time to fatigue at 90% of VO(2)MAX), and isokinetic strength (Cybex II dynamometer). Height, weight, and six skinfold measurements were also recorded. All these observational tests were completed during both the follicular and mid-luteal phases of an ovulatory menstrual cycle. Cycle phases were confirmed by assaying plasma oestradiol and progesterone. Participants were subsequently randomly assigned to either a tricyclic oral contraceptive or placebo and retested in identical fashion (oral contraceptive phase). RESULTS: Absolute and relative changes in VO(2)MAX from follicular to oral contraceptive phase decreased in the oral contraceptive group by 4.7%, whereas the placebo group showed a slight increase (+1.5%) over the same time period. Two of the women taking oral contraceptive had decreases of 4 and 9 ml/kg/min. In contrast, most women in the placebo group improved or maintained VO(2)MAX. There was also a significant increase in the sum of skinfolds in women taking oral contraceptive compared with those taking placebo (p<0.01). There were no significant changes in other physiological variables (maximum ventilation, heart rate, respiratory exchange ratio, packed cell volume) or measures of performance (anaerobic speed test, aerobic endurance, isokinetic strength) as a function of oral contraceptive treatment. CONCLUSIONS: The decrease in VO(2)MAX that occurs when oral contraceptive is taken may influence elite sporting performance in some women. Further studies are required to determine the mechanisms of this change.


Subject(s)
Contraceptives, Oral, Hormonal/pharmacology , Physical Endurance/drug effects , Sports/physiology , Adolescent , Adult , Anthropometry , Body Composition , Double-Blind Method , Female , Humans , Knee Joint/physiology , Menstrual Cycle/physiology , Physical Endurance/physiology
15.
Mol Genet Genomics ; 267(3): 391-400, 2002 May.
Article in English | MEDLINE | ID: mdl-12073041

ABSTRACT

The DNA helicase PcrA is found in gram-positive bacteria and belongs to the superfamily 1 (SF1) of helicases, together with Rep and UvrD helicases from Escherichia coli. These helicases have been extensively studied in vitro and their mode of unwinding are well characterised. However, little is known about the putative cellular partners of such helicases. To identify PcrA-interacting factors, PcrA was used as a bait in a genome-wide yeast two-hybrid screen of a Bacillus subtilis library. Three proteins with unknown functions - YxaL, YwhK and YerB - were found to interact specifically with PcrA. The yxaL gene was cloned, the product was overexpressed and purified, and its effect on the PcrA activity was investigated in vitro. YxaL enhanced the processivity of the PcrA helicase. A comparison of the amino acid sequence of YxaL with other proteins from data banks suggests that YxaL belongs to a family of proteins with a repeated domain, which adopt a typical three-dimensional structure designated as a "beta-propeller". This raises the possibility that YxaL acts as a connector protein between PcrA and another cellular component.


Subject(s)
Bacillus subtilis/metabolism , Bacterial Proteins/metabolism , Amino Acid Sequence , Bacillus subtilis/genetics , DNA Helicases/metabolism , Molecular Sequence Data , Sequence Analysis, Protein , Two-Hybrid System Techniques
16.
J Bone Miner Res ; 17(5): 834-44, 2002 May.
Article in English | MEDLINE | ID: mdl-12009014

ABSTRACT

We examined the effects of a 7-month jumping intervention (10 minutes, 3 times per week) on bone mineral gain in prepubertal Asian and white boys (10.3+/-0.6 years, 36.0+/-9.2 kg) at 14 schools randomized to control (n = 60) and intervention (n = 61) groups. Intervention and control groups had similar mean baseline and change in height, weight, lean mass and fat mass, baseline areal bone mineral density (aBMD; g/cm2), bone mineral content (BMC; g; dual-energy X-ray absorptiometry [DXA], QDR 4500W), and similar average physical activity and calcium intakes. Over 7 months, the intervention group gained more total body (TB) BMC (1.6%,p < 0.01) and proximal femur (PF) aBMD (1%, p < 0.05) than the control group after adjusting for age, baseline weight, change in height, and loaded physical activity. We also investigated the 41 Asian and 50 white boys (10.2+/-0.6 years and 31.9+/-4.4 kg) who were below the 75th percentile (19.4 kg/m2) of the cohort mean for baseline body mass index (BMI). Boys in the intervention group gained significantly more TB and lumbar spine (LS) BMC, PF aBMD, and trochanteric (TR) aBMD (+ approximately2%) than boys in the control group (adjusted for baseline weight, final Tanner stage, change in height, and loaded physical activity). Bone changes were similar between Asians and whites. Finally, we compared the boys in the control group (n = 16) and the boys in the intervention group (n = 14) whose baseline BMI fell in the highest quartile (10.5+/-0.6 years and 49.1+/-8.2 kg). Seven-month bone changes (adjusted as aforementioned) were similar in the control and intervention groups. In summary, jumping exercise augmented bone mineral accrual at several regions equally in prepubertal Asian and white boys of average or low BMI, and intervention effects on bone mineral were undetectable in high BMI prepubertal boys.


Subject(s)
Bone Density/physiology , Exercise/physiology , Asian People , Body Mass Index , Child , Humans , Male , Schools , Time Factors , White People
17.
J Bone Miner Res ; 17(3): 363-72, 2002 Mar.
Article in English | MEDLINE | ID: mdl-11874228

ABSTRACT

We compared 7-month changes in bone structural properties in pre- and early-pubertal girls randomized to exercise intervention (10-minute, 3 times per week, jumping program) or control groups. Girls were classified as prepubertal (PRE; Tanner breast stage 1; n = 43 for intervention [I] and n = 25 for control [C]) or early-pubertal (EARLY; Tanner stages 2 and 3; n = 43 for I and n = 63 for C). Mean +/- SD age was 10.0 +/- 0.6 and 10.5 +/- 0.6 for the PRE and EARLY groups, respectively. Proximal femur scans were analyzed using a hip structural analysis (HSA) program to assess bone mineral density (BMD), subperiosteal width, and cross-sectional area and to estimate cortical thickness, endosteal diameter, and section modulus at the femoral neck (FN), intertrochanter (IT), and femoral shaft (FS) regions. There were no differences between intervention and control groups for baseline height, weight, calcium intake, or physical activity or for change over 7 months (p > 0.05). We used analysis of covariance (ANCOVA) to examine group differences in changes of bone structure, adjusting for baseline weight, height change, Tanner breast stage, and physical activity. There were no differences in change for bone structure in the PRE girls. The more mature girls (EARLY) in the intervention group showed significantly greater gains in FN (+2.6%, p = 0.03) and IT (+1.7%, p = 0.02) BMD. Underpinning these changes were increased bone cross-sectional area and reduced endosteal expansion. Changes in subperiosteal dimensions did not differ. Structural changes improved section modulus (bending strength) at the FN (+4.0%, p = 0.04), but not at the IT region. There were no differences at the primarily cortical FS. These data provide insight into geometric changes that underpin exercise-associated gain in bone strength in early-pubertal girls.


Subject(s)
Bone and Bones/anatomy & histology , Bone and Bones/metabolism , Exercise Therapy/methods , Biomechanical Phenomena , Bone Density , Child , Female , Femur/anatomy & histology , Femur/growth & development , Femur/metabolism , Humans , Prospective Studies , Puberty
18.
Br J Sports Med ; 35(5): 348-51, 2001 Oct.
Article in English | MEDLINE | ID: mdl-11579072

ABSTRACT

OBJECTIVE: To test the efficacy of a community based 10 week exercise intervention to reduce fall risk factors in women with osteoporosis. METHODS: Static balance was measured by computerised dynamic posturography (Equitest), dynamic balance by timed figure of eight run, and knee extension strength by dynamometry. Subjects were randomised to exercise intervention (twice weekly Osteofit classes for 10 weeks) or control groups. RESULTS: The outcome in 79 participants (39 exercise, 40 control) who were available for measurement 10 weeks after baseline measurement is reported. After confounding factors had been controlled for, the exercise group did not make significant gains compared with their control counterparts, although there were consistent trends toward greater improvement in all three primary outcome measures. Relative to the change in control subjects, the exercise group improved by 2.3% in static balance, 1.9% in dynamic balance, and 13.9% in knee extension strength. CONCLUSIONS: A 10 week community based physical activity intervention did not significantly reduce fall risk factors in women with osteoporosis. However, trends toward improvement in key independent risk factors for falling suggest that a study with greater power may show that these variables can be improved to a level that reaches statistical significance.


Subject(s)
Accidental Falls/prevention & control , Community Health Services/statistics & numerical data , Exercise Therapy/statistics & numerical data , Osteoporosis, Postmenopausal/therapy , Aged , Analysis of Variance , British Columbia , Female , Humans , Muscle, Skeletal/physiology , Outcome Assessment, Health Care , Postural Balance , Posture , Program Evaluation , Regression Analysis , Risk Factors , Tensile Strength , Treatment Outcome
19.
J Med Virol ; 65(3): 493-504, 2001 Nov.
Article in English | MEDLINE | ID: mdl-11596084

ABSTRACT

Lamivudine, an antiviral agent, has a potential role in the treatment of recurrent or acquired de novo hepatitis B virus (HBV) infection after liver transplantation. During lamivudine therapy, residual HBV particles in serum, PBMC, and liver were quantified in 7 patients in whom hepatitis B occurred de novo (n = 4) or recurred (n = 3). HBV DNA and preS1 antigen were measured using a sensitive PCR technique and an in-house ELISA method, respectively. The genetic and antigenic properties of HBV variants that emerged during lamivudine treatment were also examined. One month after the outset of lamivudine treatment, all 7 patients remained positive for both HBV DNA and preS1 antigen in serum, reflecting residual HBV replication. At the end of therapy, four patients were considered to be lamivudine responders, including one who seroconverted to anti-HBs but remained HBV DNA positive in the liver (> 10(3) copies/microg of DNA). Among the three patients who did not respond to lamivudine, one had pol mutations (L450P and S550C) that had not been described previously, in addition to the common mutations within the YMDD locus and B domain. Defective core and preS viral proteins and atypical sedimentation profiles of HBV DNA-positive particles were observed in all three lamivudine-resistant patients. These findings confirm the persistence of HBV in liver transplant recipients despite strong inhibition of replication by lamivudine, and show abnormal viral transcription and/or morphogenesis in lamivudine-resistant patients.


Subject(s)
DNA, Viral/blood , Hepatitis B Surface Antigens/blood , Hepatitis B virus/physiology , Hepatitis B/drug therapy , Lamivudine/therapeutic use , Liver Transplantation/adverse effects , Protein Precursors/blood , Adult , Aged , Alanine Transaminase/blood , Antiviral Agents/therapeutic use , Enzyme-Linked Immunosorbent Assay , Female , Hepatitis B/virology , Hepatitis B e Antigens/blood , Humans , Male , Middle Aged , Polymerase Chain Reaction , Virion/physiology , Virus Replication
20.
J Bacteriol ; 183(19): 5772-7, 2001 Oct.
Article in English | MEDLINE | ID: mdl-11544244

ABSTRACT

The B. subtilis DeltahelD allele rendered cells proficient in transformational recombination and moderately sensitive to methyl methanesulfonate when present in an otherwise Rec(+) strain. The DeltahelD allele was introduced into rec-deficient strains representative of the alpha (recF strain), beta (addA addB), gamma (recH), epsilon (DeltarecU), and zeta (DeltarecS) epistatic groups. The DeltahelD mutation increased the sensitivity to DNA-damaging agents of addAB, DeltarecU, and DeltarecS cells, did not affect the survival of recH cells, and decreased the sensitivity of recF cells. DeltahelD also partially suppressed the DNA repair phenotype of other mutations classified within the alpha epistatic group, namely the recL, DeltarecO, and recR mutations. The DeltahelD allele marginally reduced plasmid transformation (three- to sevenfold) of mutations classified within the alpha, beta, and gamma epistatic groups. Altogether, these data indicate that the loss of helicase IV might stabilize recombination repair intermediates formed in the absence of recFLOR and render recFLOR, addAB, and recH cells impaired in plasmid transformation.


Subject(s)
Adenosine Triphosphatases/metabolism , Bacillus subtilis/genetics , DNA Helicases/metabolism , DNA Repair , Recombination, Genetic , Adenosine Triphosphatases/genetics , Bacillus subtilis/growth & development , Bacillus subtilis/metabolism , DNA Helicases/genetics
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