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Biomedical subjects

K M Khan

Publications and source records attributed to K M Khan.

At least 55 records · Page 3Linked to original sources
PubMed2001

A school-based exercise intervention augments bone mineral accrual in early pubertal girls.

OBJECTIVE: To evaluate the effects of an elementary school-based physical education exercise intervention program on bone mineral accrual in prepubertal and early pubertal girls. STUDY DESIGN: A total of 14 schools were randomly assigned to control (C) and intervention (I) groups. Girls in the I group completed a 10-minute, 3 times per week circuit of varied jumping activities over 7 months. We measured total body, lumbar spine, proximal femur, femoral neck, and trochanteric bone mineral content and areal bone mineral density and estimated femoral neck volumetric bone mineral density at baseline and final measurement in 87 girls in the I group and 90 girls in the C group. Girls were between 8.7 and 11.7 years at baseline. Tanner stage 1 girls were considered prepubertal; Tanner stages 2 and 3 girls were considered early pubertal. We used analysis of covariance (adjusting for baseline bone values, change in size, age, and maturity) to compare 7-month change in bone mineral content, areal bone mineral density, and volumetric bone mineral density between C and I groups within prepubertal and early pubertal girls. RESULTS: There was no difference in 7-month change in bone parameters between prepubertal I and C groups. Early pubertal girls in the I group gained 1.5% to 3.1% more bone at the femoral neck and lumbar spine than early pubertal girls in the C group (P <.05); gain at other sites did not differ. CONCLUSIONS: In girls, early puberty may be a particularly opportune time during growth for simple exercise interventions to have a positive effect on bone health.

Absorptiometry, Photon↗
PubMed2001

Lifestyle risk factors for osteoporosis in Asian and Caucasian girls.

PURPOSE: We investigated ethnic differences in areal bone mineral density (aBMD; g x cm(-2)) and its determinants at two levels of maturity in Asian- and Caucasian-Canadian girls. METHODS: Participants were 131 Asian (26 Tanner breast stage I (aTI) and 30 Tanner II (aTII)), and Caucasian (30 Tanner I (cTI) and 45 Tanner II (cTII)) girls. We measured calcium intake by a food frequency questionnaire, general physical activity, and extracurricular sports with a modified Physical Activity Questionnaire for Children and loaded physical activity by 7-d recall. Fat mass, lean mass, and aBMD for the total body (TB), and aBMD at the lumbar spine (LS), proximal femur (PF), femoral neck (FN), and trochanter (TR) were measured by DXA (Hologic QDR 4500). We used ANCOVA (controlling for size and lean and fat mass) to compare bone mineral content (BMC) and aBMD between ethnicities within Tanner stages. RESULTS: Calcium intake was significantly lower for Asian girls in both TI and TII (P < 0.001) as compared with Caucasians. For physical activity measures, only the general score was greater in cTI than aTI (P < 0.05). Participation in loaded physical activities and extracurricular sports was significantly less for aTII than cTII (both, P < 0.01), whereas general physical activity did not differ. aBMD measures were similar between aTI and cTI. However, TB, PF, FN, and aBMD were significantly lower (approximately 9-14%) in aTII as compared with cTII. CONCLUSION: Thus, there was greater ethnic disparity in lifestyle factors related to bone health and absolute measures of bone mineral with advanced maturity.

Anthropometry↗
PubMed2001

Changes in hip and ankle range of motion and hip muscle strength in 8-11 year old novice female ballet dancers and controls: a 12 month follow up study.

OBJECTIVES: To evaluate in a 12 month longitudinal study changes in hip and ankle range of motion and hip muscle strength in young female novice ballet dancers. METHODS: Fifty three of the original 77 (69%) female dancers aged 8-11 years and 40 of the original 49 (82%) controls returned for follow up measurements one year later. Supine right active hip external (ER) and internal (IR) rotation were measured using an inclinometer. A turnout protractor was used to assess standing active turnout range. Range of right weight bearing ankle dorsiflexion and calf muscle length were measured in a standing lunge position using an inclinometer. A manual muscle tester was used to assess right hip flexor, IR, ER, abductor and adductor strength. RESULTS: The mean (SD) 12 month change in hip ER did not differ between dancers (11.7 (11.3)degrees) and controls (8.1 (17.6)degrees). Dancers gained 12.5 (13.5)degrees hip IR which was significantly greater than controls (0.5 (13.9)degrees). Greater IR change was associated with improved IR strength (r = 0.34, p<0.001). Dancers increased total turnout (12.0 (16.7)degrees) significantly more than controls (2.2 (20.0)degrees). There was no significant change in ankle dorsiflexion range in either group. Dancers and controls increased in all measures of hip muscle strength (p<0.001) and dancers achieved significantly greater gains in three out of five muscle groups (all, p<0.05). CONCLUSIONS: Total hip range of motion increased in both ballet students and controls at this young age. However, ankle dorsiflexion did not, which is probably due to this movement being blocked by bony apposition, rather than soft tissue stretch. This has implications for ballet teachers, as it has long been accepted that this movement could be improved with training. Dancers had greater increases in hip strength after 12 months compared with controls in muscles specific for ballet, suggesting that hip strength can be trained at this young age. Whether these gains are permanent requires further study.

Analysis of Variance↗
PubMed2001

A randomised clinical trial of the efficacy of drop squats or leg extension/leg curl exercises to treat clinically diagnosed jumper's knee in athletes: pilot study.

OBJECTIVES: To compare the therapeutic effect of two different exercise protocols in athletes with jumper's knee. METHODS: Randomised clinical trial comparing a 12 week programme of either drop squat exercises or leg extension/leg curl exercises. Measurement was performed at baseline and after six and 12 weeks. Primary outcome measures were pain (visual analogue scale 1-10) and return to sport. Secondary outcome measures included quadriceps and hamstring moment of force using a Cybex II isokinetic dynamometer at 30 degrees/second. Differences in pain response between the drop squat and leg extension/curl treatment groups were assessed by 2 (group) x 3 (time) analysis of variance. Two by two contingency tables were used to test differences in rates of return to sport. Analysis of variance (2 (injured versus non-injured leg) x 2 (group) x 3 (time)) was also used to determine differences for secondary outcome measures. RESULTS: Over the 12 week intervention, pain diminished by 2.3 points (36%) in the leg extension/curl group and 3.2 points (57%) in the squat group. There was a significant main effect of both exercise protocols on pain (p<0.01) with no interaction effect. Nine of 10 subjects in the drop squat group returned to sporting activity by 12 weeks, but five of those subjects still had low level pain. Six of nine of the leg extension/curl group returned to sporting activity by 12 weeks and four patients had low level pain. There was no significant difference between groups in numbers returning to sporting activity. There were no differences in the change in quadriceps or hamstring muscle moment of force between groups. CONCLUSIONS: Progressive drop squats and leg extension/curl exercises can reduce the pain of jumper's knee in a 12 week period and permit a high proportion of patients to return to sport. Not all patients, however, return to sport by that time.

Adolescent↗
PubMed2001

Reproducibility and clinical utility of tendon palpation to detect patellar tendinopathy in young basketball players. Victorian Institute of Sport tendon study group.

BACKGROUND: Palpation is an important clinical test for jumper's knee. OBJECTIVES: To (a) test the reproducibility of palpation tenderness, (b) evaluate the sensitivity and specificity of palpation in subjects with clinical symptoms of jumper's knee, and (c) determine whether tenderness to palpation may serve as a useful screening test for patellar tendinopathy. The yardstick for diagnosis of patellar tendinopathy was ultrasonographic abnormality. METHODS: In 326 junior symptomatic and asymptomatic athletes' tendons, palpation was performed by a single examiner before ultrasonographic examination by a certified ultrasound radiologist. In 58 tendons, palpation was performed twice to test reliability. Tenderness to palpation was scored on a scale from 0 to 3 where 0 represented no pain, and 1, 2, and 3 represented mild, moderate, and severe tenderness respectively. RESULTS: Patellar tendon palpation was a reliable examination for a single examiner (Pearson r = 0.82). In symptomatic tendons, the positive predictive value of palpation was 68%. As a screening examination in asymptomatic subjects, the positive predictive value of tendon palpation was 36-38%. Moderate and severe palpation tenderness were better predictors of ultrasonographic tendon pathology than absent or mild tenderness (p<0.001). Tender and symptomatic tendons were more likely to have ultrasound abnormality than tenderness alone (p<0.01). CONCLUSIONS: In this age group, palpation is a reliable test but it is not cost effective in detecting patellar tendinopathy in a preparticipation examination. In symptomatic tendons, palpation is a moderately sensitive but not specific test. Mild tenderness in the patellar tendons in asymptomatic jumping athletes should be considered normal.

Adolescent↗
PubMed2001

The VISA-A questionnaire: a valid and reliable index of the clinical severity of Achilles tendinopathy.

BACKGROUND: There is no disease specific, reliable, and valid clinical measure of Achilles tendinopathy. OBJECTIVE: To develop and test a questionnaire based instrument that would serve as an index of severity of Achilles tendinopathy. METHODS: Item generation, item reduction, item scaling, and pretesting were used to develop a questionnaire to assess the severity of Achilles tendinopathy. The final version consisted of eight questions that measured the domains of pain, function in daily living, and sporting activity. Results range from 0 to 100, where 100 represents the perfect score. Its validity and reliability were then tested in a population of non-surgical patients with Achilles tendinopathy (n = 45), presurgical patients with Achilles tendinopathy (n = 14), and two normal control populations (total n = 87). RESULTS: The VISA-A questionnaire had good test-retest (r = 0.93), intrarater (three tests, r = 0.90), and interrater (r = 0.90) reliability as well as good stability when compared one week apart (r = 0.81). The mean (95% confidence interval) VISA-A score in the non-surgical patients was 64 (59-69), in presurgical patients 44 (28-60), and in control subjects it exceeded 96 (94-99). Thus the VISA-A score was higher in non-surgical than presurgical patients (p = 0.02) and higher in control subjects than in both patient populations (p<0.001). CONCLUSIONS: The VISA-A questionnaire is reliable and displayed construct validity when means were compared in patients with a range of severity of Achilles tendinopathy and control subjects. The continuous numerical result of the VISA-A questionnaire has the potential to provide utility in both the clinical setting and research. The test is not designed to be diagnostic. Further studies are needed to determine whether the VISA-A score predicts prognosis.

Achilles Tendon↗
PubMed2001

Results of a 10 week community based strength and balance training programme to reduce fall risk factors: a randomised controlled trial in 65-75 year old women with osteoporosis.

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.

Accidental Falls↗
PubMed2001

Assessment of a low-intensity cardiac rehabilitation programme using the six-minute walk test.

OBJECTIVE: To examine the utility of the six-minute walk test (6'WT), in assessing the effectiveness of a six-week cardiac rehabilitation programme, of which exercise training was an integral part. SETTING: Royal Liverpool and Broad Green Hospitals Rehabilitation Unit. DESIGN: Two hundred and thirty-nine consecutive patients referred for cardiac rehabilitation were allocated to one of two groups. In group A 209 entered and 159 completed the usual rehabilitation programme whilst group B patients (n = 30) acted as a control by deferring entry to the programme for six weeks, continuing only activities of daily living. OUTCOME MEASURES: Both groups were assessed using the 6'WT, peak expiratory flow rate (PEFR) and isometric grip strength at enrolment and six weeks. RESULTS: At baseline, groups A and B were demographically identical without significant differences in terms of 6'WT, PEFR or grip strength. Following the study period, group A showed a significant increase in 6'WT from 314.7 +/- 76.2 to 377.3 +/- 78.6 m, in PEFR from 406.9 +/- 115.9 to 437.8 +/- 118.6 litres per minute and in grip strength from 28.8 +/- 9.31 to 30.3 +/- 8.93 kg, all p < 0.001. There were no significant changes in group B. CONCLUSIONS: The 6'WT proved to be a simple and effective measurement of functional capacity in patients performing cardiac rehabilitation. The clinical programme investigated successfully increased patients' functional capacity as assessed by the 6'WT. Significant improvement in PEFR and grip strength was also demonstrated, compared with a control population.

Aged↗
PubMed2001

Exercise in the prevention of falls in older people: a systematic literature review examining the rationale and the evidence.

Falls are a major source of death and injury in elderly people. For example, they cause 90% of hip fractures and the current cost of hip fractures in the US is estimated to be about 10 billion dollars. Age-related changes in the physiological systems (somatosensory, vestibular and visual) which contribute to the maintenance of balance are well documented in older adults. These changes coupled with age-related changes in muscle and bone are likely to contribute to an increased risk of falls in this population. The integrated rehabilitation-based model of fall risk factors reveals multiple sites for interventions that may reverse fall risk factors. Regular exercise may be one way of preventing falls and fall-related fractures. The evidence for this contention comes from a variety of sources. On the basis of 9 randomised controlled studies conducted since 1996, exercise appears to be a useful tool in fall prevention in older adults, significantly reducing the incidence of falls compared with control groups. However, current limitations such as inconsistencies in the measurement of key dependent and independent variables do not, at present, permit a meta-analysis of intervention trials. Further investigation, using trials designed with the current limitations in mind, is necessary to establish the optimum exercise programme to maximise fall prevention in older adults.

Accidental Falls↗
PubMed2000

Immunohistochemical localization of adenylyl cyclase isoforms in the lateral wall of the rat cochlea.

The enzymatic activity of adenylyl cyclase (AC) is attributable to nine isoforms with individual pharmacology and tissue distribution. Polyclonal antibodies for AC isoforms I-IV, VII and VIII were applied to sections of cochlear lateral wall, a tissue involved in ion transport contributing to the unique ion content of endolymph and electrical potential of scala media. Within the stria vascularis, immunoreactivity primarily to Ca(2+)/calmodulin-independent isoforms II, IV and VII was localized to sites consistent in position to the basolateral extensions of marginal cells. Little immunoreactivity was observed in the stria vascularis for Ca(2+)/calmodulin-dependent isoforms I, III and VIII. Within the spiral ligament, type II and type IV fibrocytes exhibited moderate staining for ACII, IV and VII, less staining for VIII and little for I and III. Immunoreactivity to ACII, IV, VII and VIII was observed in type I fibrocytes. The outer sulcus cells and root processes were highly immunoreactive for isoforms I and VIII, but not for III or the Ca(2+)/calmodulin-independent isoforms. The differential pattern of immunoreactivity in the lateral wall overall appears to reflect subfamily-specific expression with Ca(2+)/calmodulin-independent isoforms expressed in the stria vascularis and Ca(2+)/calmodulin-dependent isoforms expressed in the outer sulcus cells and root processes. cAMP-mediated modulation of ion transport by marginal cells is predicted to exhibit, in the microenvironment of basolateral membrane infoldings, pharmacological characteristics of the AC type II subfamily (II, IV and VII), including activation by protein kinase C (II and VII).

Adenylyl Cyclases↗
PubMed2000

Selective activation of MAPK(erk1/2) by laminin-1 peptide alpha1:Ser(2091)-Arg(2108) regulates macrophage degradative phenotype.

Components of the extracellular matrix contain cryptic domains, which are exposed by proteolysis and elicit biological responses distinct from intact molecules. The disparate cellular response to extracellular matrix fragments and parent intact molecules suggests differential recognition and signaling pathways. In experiments reported here, we demonstrate that urokinase and matrix metalloproteinase-9 expression by RAW264.7 macrophages is stimulated by a synthetic laminin peptide derived from the alpha1-chain (SRARKQAASIKVAVSADR), whereas intact laminin-1 has no effect on proteinase expression by macrophages. Incubation of macrophages with alpha1:SRARKQAASIKVAVSADR stimulates tyrosine phosphorylation of several proteins including mitogen-activated protein kinase (MAPK)(erk1/2). In contrast, neither intact laminin-1 nor the beta1-chain peptide CDPGYIGSR stimulated protein tyrosine phosphorylation in these cells. Inhibition of tyrosine kinases or protein kinase C blocked alpha1-chain peptide-induced phosphorylation of MAPK(erk1/2) and the up-regulation of steady state levels of urokinase mRNA and matrix metalloproteinase-9 activity. A MAPK kinase inhibitor blocked alpha1-chain-induced phosphorylation of MAPK(erk1/2) and the induction of proteinase expression. Intact laminin-1, which was unable to induce macrophage proteinase expression, failed to stimulate the phosphorylation of MAPK(erk1/2). These data demonstrate that incubation of macrophages with alpha1:SRARKQAASIKVAVSADR, but not intact laminin-1, triggers protein kinase C-dependent activation of MAPK(erk1/2), leading to the up-regulation of proteinase expression.

Amino Acid Sequence↗
PubMed2000

Lifestyle determinants of bone mineral: a comparison between prepubertal Asian- and Caucasian-Canadian boys and girls.

The purpose of this study was to examine the difference in lifestyle and morphometric factors that affect bone mineral and the attainment of peak bone mass in 168 healthy Asian (n = 58) and Caucasian (n = 110) Canadian, prepubertal girls and boys (mean age 8.9+/-0.7) living in close geographical proximity. DXA (Hologic 4500) scans of the proximal femur (with regions), lumbar spine, and total body (TB) were acquired. We report areal bone mineral densities (aBMD g/cm(2)) at all sites and estimated volumetric density (aBMD, g/cm(3)) at the femoral neck. Dietary calcium, physical activity, and maturity were estimated by questionnaire. Of these prepubertal children, all of the boys and 89% of the girls were Tanner stage 1. A 2x2 ANOVA demonstrated no difference between ethnicities for height, weight, body fat, or bone mineral free lean mass. Asian children consumed significantly less dietary calcium (35%) on average and were significantly less active (15%) than their Caucasian counterparts (P<0.001). There were significant ethnicity main effects for femoral neck bone mineral content (BMC) and alphaBMD (both P<0.001) and significant sex by ethnicity interactions (P<0.01). The Asian boys had significantly lower femoral neck BMC (11%), aBMD (8%), and vBMD (4.4%). At the femoral neck, BMFL mass, sex, and physical activity explained 37% of the total variance in aBMD (P<0.05). In summary, this study demonstrated differences in modifiable lifestyle factors and femoral neck bone mineral between Asian and Caucasian boys.

Asian People↗
PubMed2000

Augmented trochanteric bone mineral density after modified physical education classes: a randomized school-based exercise intervention study in prepubescent and early pubescent children.

BACKGROUND: Of the few exercise intervention studies focusing on pediatric populations, none have confined the intervention to the scheduled physical education curriculum. OBJECTIVE: To examine the effect of an 8-month school-based jumping program on the change in areal bone mineral density (aBMD), in grams per square centimeter, of healthy third- and fourth-grade children. STUDY DESIGN: Ten elementary schools were randomized to exercise (n = 63) and control groups (n = 81). Exercise groups did 10 tuck jumps 3 times weekly and incorporated jumping, hopping, and skipping into twice weekly physical education classes. Control groups did regular physical education classes. At baseline and after 8 months of intervention, we measured aBMD and lean and fat mass by dual-energy x-ray absorptiometry (Hologic QDR-4500). Calcium intake, physical activity, and maturity were estimated by questionnaire. RESULTS: The exercise group showed significantly greater change in femoral trochanteric aBMD (4.4% vs 3.2%; P <.05). There were no group differences at other sites. Results were similar after controlling for covariates (baseline aBMD change in height, change in lean, calcium, physical activity, sex, and ethnicity) in hierarchical regression. CONCLUSIONS: An easily implemented school-based jumping intervention augments aBMD at the trochanteric region in the prepubertal and early pubertal skeleton.

Absorptiometry, Photon↗
PubMed2000

Studies of surgical outcome after patellar tendinopathy: clinical significance of methodological deficiencies and guidelines for future studies. Victorian Institute of Sport Tendon Study Group.

Patellar tendinopathy is often treated surgically after failure of conservative treatment but clinical experience suggests that results are not uniformly excellent. The aim of this review was to (i) identify the different surgical techniques that have been reported and compare their success rates, and (ii) critically assess the methodology of studies that have reported surgical outcomes. Twenty-three papers and two abstracts were included in the review. Surgical procedures were categorized and outcomes summarized. Using ten criteria, an overall methodology score was derived for each paper. Criteria for which scores were generally low (indicating methodological deficiency) concerned the type of study, subject selection process and outcome measures. We found a negative correlation between papers' reported success rates and overall methodology scores (r= -0.57, P<0.01). There was a positive correlation between year of publication and overall methodology score (r=0.68, P<0.001). We conclude that study methodology may influence reported surgical outcome. We suggest practical guidelines for improving study design in this area of clinical research, as improved study design would provide clinicians with a more rigorous evidence-base for treating patients who have recalcitrant patellar tendinopathy.

Bias↗
PubMed2000

Patellar tendinopathy in junior basketball players: a controlled clinical and ultrasonographic study of 268 patellar tendons in players aged 14-18 years.

Anterior knee pain is a common presenting complaint amongst adolescent athletes. We hypothesised that patellar tendinopathy may occur at a younger age than is generally recognised. Thus, we studied the patellar tendons in 134 elite 14- to 18-year-old female (n=64) and male (n=70) basketball players and 29 control swimmers (17 female, 12 male) clinically and with ultrasonography. We found that of 268 tendons, 19 (7%) had current patellar tendinopathy on clinical grounds (11% in males, 2% in females). Twenty-six percent of the basketball players' patellar tendons contained an ultrasonographic hypoechoic region. Ultrasonographic abnormality was more prevalent in the oldest tertile of players (17-18 years) than the youngest tertile (14-15.9 years). Of tendons categorised clinically as 'Never patellar tendinopathy', 22% had an ultrasonographic hypoechoic region nevertheless. This study indicates that patellar tendinopathy can occur in 14- to 18-year-old basketball players. Ultrasonographic tendon abnormality is 3 times as common as clinical symptoms.

Adolescent↗