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Biomedical subjects

K M Chan

Publications and source records attributed to K M Chan.

At least 163 records · Page 9Linked to original sources
PubMed1996

Eccentric and concentric isokinetic knee flexion and extension: a reliability study using the Cybex 6000 dynamometer.

OBJECTIVE: To determine the reliability of the Cybex 6000 isokinetic dynamometer in measuring the knee muscle performance concentrically and eccentrically. METHODS: 18 male and 12 female subjects with no previous knee injuries, who had not previously undergone any isokinetic testing, were studied. The flexor and extensor muscles groups of both knees were tested at 60 degrees s-1 and 120 degrees s-1 with the continuous concentric-eccentric cycle testing protocol. Variables studied included peak torque, total work, and average power. The interclass correlation coefficient (ICC 2,1) was used to determine the reliability with P < 0.05. RESULTS: Peak torque showed significantly greater ICC than the total work and average power, with test-retest reliability ranging from 0.82 to 0.91 for peak torque, from 0.76 to 0.89 for total work, and 0.71 to 0.88 for average power. Average variability for the three variables studied ranged from 9% to 14%. The ICCs for the three variables studied were significantly greater at 120 degrees s-1. The knee extensor muscle group showed greater test-retest reliability, and the results of isokinetic testing in the concentric contraction mode were more reproducible. CONCLUSIONS: The Cybex 6000 isokinetic dynamometer shows high reliability in measuring isokinetic concentric and eccentric variables. Some fluctuation should be allowed when evaluating variations of muscle performance between tests.

Adult↗
PubMed1996

Isokinetic strength of the quadriceps and hamstrings and functional ability of anterior cruciate deficient knees in recreational athletes.

OBJECTIVE: To test the hypothesis that increasing the hamstrings and quadriceps (H:Q) isokinetic strength ratio will, in the short term, improve the functional ability of an anterior cruciate ligament (ACL) deficient knee. METHODS: The isokinetic muscular characteristics at a speed of 60 degrees s-1 and 180 degrees s-1 of 46 recreational athletes with an arthroscopically confirmed ACL tear were determined using the Cybex II+ isokinetic dynamometer. The variables tested included peak torque, endurance ratio, total work output, and explosive power. Functional ability was scored with the Cincinnati rating system, measuring the severity of pain and swelling, the degree of giving way, and the overall ability to walk, run, ascent and descent stairs, jump and twist. RESULTS: Among all muscular characteristics, the H:Q ratio at 180 degrees s-1 at 30 degrees of knee flexion was shown to have the highest correlation to the functional score (r = 0.6249, P < 0.001). All variables involving hamstring strength were shown to be significantly correlated to the functional ability score (P < 0.01), while none of the variables involving quadriceps strength showed significant correlation with the functional ability of the injured knee. CONCLUSIONS: The H:Q ratio is strongly correlated to the functional ability of ACL deficient knees in Chinese recreational athletes. It could be used as an additional measure to guide in the decision making process in the management of ACL deficient knees.

Adult↗
PubMed1996

Paediatric sports injuries in Hong Kong: a seven year survey.

OBJECTIVE: To ascertain the epidemiological characteristics of sports injuries in children in Hong Kong. METHODS: Retrospective review of all cases seen in the Sports Injury Clinic of the Prince of Wales Hospital, Shatin, Hong Kong, in the period May 1984 to December 1990. The variables studied were age at presentation, gender, side of the body injured, anatomical location of the injury, type and severity of injury, sport played, level (school, recreational, amateur and professional) and frequency of sports participation, length in years of sports practice, and initial management of the injury. RESULTS: Of the 2293 patients seen, 238 were youngsters (54% boys) 16 years old or younger. Ball games accounted for the greatest number of injuries, with 37 children taking part in basketball, 28 in soccer, 12 in volleyball, and 31 children taking part in a variety of other ball games. Of the remaining children, the single largest group was practising track and field, with sprinting and middle distance running accounting for 42 injuries, and 28 children were injured while cycling. Most of the injuries (85%) were classified as non-serious, but 15% of children presented with a total of 21 fractures, two joint dislocations, five concussions, and seven torn knee ligaments. CONCLUSIONS: Children sports participation in Hong Kong, although not at high level and not as widespread as in the West, accounts for significant morbidity. These injuries should be carefully monitored to ascertain whether they result in any detrimental long term effects.

Adolescent↗
PubMed1996

Athletic knee injuries. Similarities and differences between Asian and Western experience.

The pattern and prevalence of knee injuries among athletes are different in Asia, Europe, and North America because of factors such as the different sporting cultures of the regions and the type of favorite sports. Sampling and data bias and the variable levels of diffusion of sports in the different parts of the world also are responsible for the variation. In this review, the knee emerges as the most commonly injured part of the body; such injuries present significant problems of mechanical block or instability that may compromise athletic performance. Sports specific injuries are delineated, and specific groups, such as children and adolescents, female, and master athletes, are reviewed in light of the characteristic patterns of knee injuries. Differences in the patients' attitude, health care systems, and consultations of traditional medical practitioners produce major differences in management styles. However, it is encouraging to find a concerted effort on all continents in the search for a better understanding of knee injuries and a more satisfactory coordination between clinical and basic science research in this field.

Adolescent↗
PubMed1996

Insulin-like growth factor IEa2 is the predominantly expressed form of IGF in common carp (Cyprinus carpio).

An insulin-like growth factor (IGF) complementary DNA (cDNA) was isolated from a liver cDNA library of adult common carp, Cyprinus carpio. The identity of this cDNA clone was confirmed by nucleotide sequence determination. Sequence comparison with other vertebrate and rainbow trout IGFs showed that this cDNA encodes a particular subtype of IGF-I, IGF-IEa2. A reverse transcription-polymerase chain reaction (RT-PCR) assay showed that this IGF-I is expressed mainly in the liver (hepatopancreas) of adult common carp. Analyses of 26 other cDNA clones isolated from the same library (using a probe carrying the conserved region of the common carp IGF-IEa2 cDNA clone) showed that these clones represent different insert sizes of the same IGF-IEa2. In conclusion, IGF-IEa2 is the predominantly expressed IGF in the liver of adult common carp.

Amino Acid Sequence↗
PubMed1996

Brachial plexus injury in association with fracture-dislocation of the shoulder.

Anterior dislocation of the shoulder is generally not associated with neurological compromise. We report three patients in whom a brachial plexus injury was caused by an anterior dislocation of the shoulder. One patient was further complicated by vascular involvement. The forces producing the injury are usually small, and the neurological trauma is likely to be neuropraxia. Conservative management is usually successful, and, in our patients, recovery took place after an average of six months.

Adolescent↗
PubMed1995

Interactive events subserving the pupillary light reflex in pigmented and albino rats.

The consensual pupilloconstrictor response requires the intensity information that is delivered to each eye to be integrated to produce an averaged response such that the pupillary diameter in each eye is equal. Here we have examined how luminance information from each eye is integrated in the rat and where the integration occurs, using a pupillometry system to record pupillary diameter after illumination of one or both eyes. In albino rats the size of the uncrossed optic pathway to the pupilloconstrictor centre, the olivary pretectal nucleus, is reduced three-fold and there is a concomitant but less dramatic reduction in the size of the consensual response. Unilateral lesions of the olivary pretectal nucleus in pigmented rats restrict all optic input to the opposite pretectum. Stimulation of one or both eyes in these animals suggests that integration occurs not only at the level of the olivary pretectal nucleus, but also downstream in the Edinger-Westphal nucleus. Parallels with human studies and the opportunity to perform secondary lesions suggests the rat may provide a good model in which to study the substrates of the pupilloconstrictor response and mechanisms of integration of convergent parallel inputs in general.

Animals↗
PubMed1995

Coordinated regulation of synapsin I interaction with F-actin by Ca2+/calmodulin and phosphorylation: inhibition of actin binding and bundling.

The synapsins are a family of synaptic vesicle phosphoproteins whose role seems to be to limit the availability of small synaptic vesicles for exocytosis by linking them to the cytoskeleton. One member of the family, synapsin I, has been shown to bind calmodulin in a Ca(2+)-dependent manner. In this study, we have examined whether or not calmodulin can regulate one of the activities of synapsin I, namely, its interaction with F-actin. Synapsin I is an actin bundling protein: this activity is controlled by phosphorylation. Here we show that calmodulin in the presence of Ca2+ is a competitive inhibitor of both actin binding and bundling by synapsin I. Under the conditions of our assay (0.45 microM synapsin I, 4 microM F-actin), half-maximal inhibition of actin binding and bundling by unphosphorylated synapsin I was found with 4.3 and 3.7 microM calmodulin, respectively. The actin binding activity of synapsin I phosphorylated by cAMP-dependent protein kinase or by calmodulin-dependent protein kinase II showed similar sensitivity to calmodulin inhibition to unphosphorylated synapsin I. However, inhibition of bundling was potentiated. Half-maximal inhibition of bundling by synapsin I phosphorylated by cAMP-dependent kinase was achieved at approximately 0.5 microM calmodulin. Half-maximal inhibition of bundling by synapsin I phosphorylated by calmodulin-dependent protein kinase II was achieved at less than 0.2 microM calmodulin, although the maximum binding under the conditions of the assay was lower.(ABSTRACT TRUNCATED AT 250 WORDS)

Actins↗
PubMed1995

Uncemented porous-coated anatomic total hip replacement in Chinese patients.

Primary uncemented Porous-Coated Anatomic total hip replacement was carried out in 72 hips in 62 Chinese patients. Their average age was 50 years and the average follow up was 3 1/2 years. The most common diagnosis was avascular necrosis. The average preoperative Harris score of 36.3 points improved to 83.2 at the last follow up. The pain score improved from 13.7 out of 44 to an average of 42. Seven of 8 hips with thigh pain had an inadequately fitting stem which had subsided. Only one cup was revised because of a technical error and one femoral component for loosening. Uncemented Porous-Coated Anatomic total hip replacement gave good early results in Chinese patients.

Activities of Daily Living↗
PubMed1995

Methods for estimating the numbers of motor units in human muscles.

After the introduction by A. J. McComas of the original method for estimating the number of motor units based on manual incremental stimulation of a motor nerve, several new techniques have been developed, designed to correct for some of the errors inherent in the original technique. These methods incorporate algorithms to adjust for alternation and, to a greater or lesser extent, automate the methods, rendering the techniques less subject to operator bias and various physiological and technical errors. This review explores the advantages and drawbacks in the multiple-point stimulation (MPS), spike-triggered averaging (STA), and decomposition-enhanced STA techniques, illustrates some of the current applications of the techniques, and explores some tantalizing prospects for new studies of motor-unit physiology in the future.

Algorithms↗
PubMed1995

The effect of dance training on menstrual function in collegiate dancing students.

A total of 98 dancing students from a collegiate school of dancing were studied through interview using a highly structured questionnaire to elicit details of the duration and intensity of dance training, menstrual patterns and musculoskeletal injuries sustained during training; 70 (72%) of these dancing students were eumenorrhoeic, while 15 (15.4%) had oligomenorrhoea. Thirteen (13.4%) either had amenorrhoea for over 90 days at the time of the study, or were on hormonal treatment because of amenorrhoea for over 3 months in the past 1 year. Those who were amenorrhoeic had longer training hours per week when compared with eumenorrhoeic and oligomenorrhoeic students. Both oligomenorrhoeic and amenorrhoeic students had a lower body mass index (18.25 kg/m2 and 18.26 kg/m2 versus 19.45 kg/m2, p < 0.01), and a higher incidence of musculoskeletal injuries and chronic orthopaedic problems compared to eumenorrhoeic ones. Ballet students had a higher incidence of menstrual dysfunction and musculoskeletal injuries as compared to classic Chinese dance, modern dance and musical theatre dance students as well as a significantly lower average body mass index. These data suggest a proportional correlation between menstrual dysfunction and proneness to musculoskeletal injuries in training, which could be explained by a hormonal mechanism.

Adult↗
PubMed1995

Influences of secretory activities in rat submandibular glands on tissue kallikrein circulating in the blood.

Changes in serum levels of rat tissue kallikrein (rK1) in venous blood were measured, using a newly developed radioimmunoassay, before and after autonomic nerve stimulations of submandibular salivary secretion. rK1 secreted into saliva under these conditions was measured by radioimmunoassay and by enzymic activity assay, using the fluorogenic peptide substrate D-Val-Leu-Arg-7-amino-4-trifluoromethylcoumarin (AFC). Following an overnight fast, serum rK1 concentration was 30-40 ng ml-1. Unilateral electrical stimulation of the submandibular sympathetic nerve supply (at 50 Hz in bursts of 1 s every 10 s for 60 min) evoked a small flow of saliva with a very high rK1 concentration, resulting in a large output of rK1 of 2104.4 +/- 603.5 micrograms (n = 6). Such stimulation caused a large degranulation of granular duct cells and a corresponding reduction in glandular rK1 content. Unilateral electrical stimulation of the parasympathetic nerve supply (at 5 Hz continuously for 60 min) evoked a copious flow of saliva with a very low rK1 concentration, resulting in a low output of rK1 (18.1 +/- 4.9 micrograms; n = 6). Despite these large differences in salivary outputs of rK1, serum concentrations of rK1 were increased similarly following either sympathetic or parasympathetic stimulation by 48 and 46%, respectively. If the submandibular duct was briefly obstructed during sympathetic stimulation, inducing leakage and glandular oedema, then serum rK1 increased greatly (40-fold); a similar increase to that seen by others in previous studies without deliberate obstruction. Four days after bilateral submandibular-sublingual sialadenectomy serum rK1 concentration was reduced by approximately 50%. The results indicate that submandibular glands normally contribute to circulating levels of rK1 in rats, but this contribution is independent of the amounts of rK1 secreted into saliva by sympathetically induced exocytosis, and is likely to arise from basal vesicular transport. However, if glandular leakage occurs during sympathetic stimulation of submandibular secretion this then causes increases in the circulating levels of rK1 that correlate with the large amounts being secreted into saliva.

Animals↗
PubMed1995

Bilateral isokinetic variables of the shoulder: a prediction model for young men.

Clinicians frequently want to know the pre-injury strength of an uninjured limb. The purpose of this study was to delineate the differences in bilateral isokinetic peak torque (PT) at 60 degrees and 240 degrees, and torque acceleration energy (TAE), average power (AP) and total work (TW) at 240 degrees during shoulder extension and flexion movements, and to develop a method to determine the expected maximal isokinetic variables of the dominant shoulder based upon isokinetic measurements from the non-dominant shoulder. Shoulder isokinetic measurements were obtained from 30 normal young male adults. While bilateral correlation was significant (P < 0.01), results also suggest significant bilateral differences P < 0.01). Thus, it is inappropriate to use the uninjured extremity to predict the pre-injured strength of the injured side without adjustment. In this investigation models were developed relating the expected maximal isokinetic measurement of the dominant shoulder to the non-dominant shoulder measurements.

Acceleration↗
PubMed1995

A quantifiable approach in the comparison of isokinetic assessment data--new correlation equations for the Johnson antishear device and standard shin pad in the isokinetic assessment of the knee.

The rehabilitation of the knee with a deficient anterior cruciate ligament (ACL) always presents a great challenge. Isokinetic assessment allows muscle performance to be quantified. The antishear device, introduced by Johnson, has the distinct advantage of minimizing the anterior translation force during isokinetic exercise. In a previous report, there was a significant difference between the Johnson double pad antishear device and the standard single pad device in knee extension. The main purpose of this study was to define a correlation equation such that data generated in the use of the two different devices can be compared for assessment. Ten subjects were tested with the Cybex isokinetic dynamometer with a randomly selected sequence of test speeds. Correlation coefficient (r), regression analysis and paired t tests (P) were performed to estimate the correlation and difference between the two devices. It is concluded that a significant difference in the data generated between the two devices indicated that a single device should be selected to carry out a series of comparisons on a particular subject. However, if the two devices are used in a series of testings, a set of correlation equations has been defined to facilitate such comparison. The findings in this study will widen the application of comparison of isokinetic data in the quantitative approach of rehabilitation of the knee with a deficient anterior cruciate ligament.

Adult↗
PubMed1995

Systemic lupus erythematosus--not to be forgotten in the elderly.

A 70-year-old woman presented with a skin rash, chronic headaches, congestive cardiac failure, and a moderate pericardial effusion. These were attributed to systemic lupus erythematosus (SLE). She responded to a moderate dose of corticosteroids. SLE though rare in the elderly is a disorder that should not be forgotten.

Age of Onset↗