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Biomedical subjects

F Chan

Publications and source records attributed to F Chan.

At least 55 records · Page 3Linked to original sources
PubMed1989

Bone mineralisation in preterm infants measured by dual energy radiographic densitometry.

Dual energy radiographic densitometry was used to follow postnatal changes in the bone mineral content of the radii of 15 infants of less than 30 weeks' gestation. The system permitted bone mineral content to be measured with minimal disturbance to the infants in their incubators. Mean bone mineral content at birth was 2.4 mg/mm shaft length, decreasing to 1.9 mg/mm at 6 weeks of age, before starting to rise. Mineralisation was poor compared with that of a fetus at an equivalent postconceptual age. Mean intakes of calcium and phosphate were considerably less than the intrauterine accumulation of these minerals and it is postulated that this was the main cause of the poor mineralisation. Radiographic densitometry is both accurate and precise and has advantages over photon absorptiometry in that it can be used to measure bone mineral in infants who are not only preterm, but also ill enough to require intensive care.

Aging↗
PubMed1988

The Carpentier-Edwards standard porcine bioprosthesis: long-term evaluation of the high pressure glutaraldehyde fixed prosthesis.

The Carpentier-Edwards standard porcine bioprosthesis was implanted in 1,000 operations (988 patients with 1,092 valves) between 1975 and 1981. The mean age of the patients was 56.8 years (range 8 to 85 years). During the years 1975 and 1981, approximately 97% of the total valvular surgery population received the prosthesis. The early mortality was 7.8% (including patients with concomitant procedures including coronary artery bypass and ascending aortic aneurysm resection). Late mortality was 3.8% per patient-year. The total cumulative follow-up was 5,937 years. Thromboembolism (TE) was 1.3% per patient-year (fatal 0.4%/patient-year) (minor 0.4%; major 0.9%); antithromboembolic therapy-related hemorrhage (ATH) 0.5% (fatal 0.1%); prosthetic valve endocarditis (PVE) 0.5% (fatal 0.2%); periprosthetic leak (PPL) 0.4% (fatal 0.2%); clinical valve dysfunction (CVD) 0.2% (fatal 0.02%); and structural valve deterioration (SVD)/primary tissue failure 1.6% per patient-year (fatal 0.2%/pt-yr). Thromboembolism and SVD occurring primarily between the sixth and tenth year of evaluation, were the significant complications. The overall patient survival was 60.5% +/- 2.4% at 10 years. The patients were classified as 93.5% NYHA functional Class III and IV, preoperatively and 93.1% Class I and II, postoperatively. The freedom at 10 years from TE was 82.9% +/- 2.7%; SVD 76.9% +/- 2.9%; and reoperation 70.8% +/- 3.1%. Freedom from all valve-related complications at 10 years was 54.3% +/- 3.1%; valve-related mortality 86.4% +/- 2.3%; mortality and reoperation (valve failure) 64.0% +/- 3.2%; mortality and residual morbidity (treatment failure) 82.3% +/- 2.6%; and mortality, residual morbidity, and reoperation (valve failure and dysfunction) 60.6% +/- 3.2%. There were 61 valve-related deaths of a total 352 deaths (early 7, late 54) (TE 21; ATH 7; CVD 1; PVE 12; PPL 9; and SVD 11). Valve-related reoperations were performed in 128 patients (TE 3; CVD 4; PVE 14; PPL 17; and SVD 90). The standard Carpentier-Edwards porcine bioprosthesis has provided very satisfactory clinical performance and afforded patients excellent quality of life. Primary tissue failure is the significant long-term complication.

Adolescent↗
PubMed1988

Differential attitudes of Chinese students toward people with disabilities: a cross-cultural perspective.

The purpose of this study was to examine the attitudes of 338 Chinese secondary school students toward three major disability groups (people who are physically disabled, emotionally disturbed, and mentally retarded) using an adaptation of the American Scale of Attitudes toward Disabled Persons (SADP). We found that physically disabled persons were rated higher across the three subscales of the SADP compared to either emotionally disturbed and mentally retarded individuals, who were rated similarly low by the students. The lack of differentiation between the two mental handicapping conditions is at variance with contemporary western findings. The overall negative attitudes toward people with mental disabilities may have significant implications for community rehabilitation programming for this population.

Adolescent↗
PubMed1987

Effect of optic nerve denervation on lens regeneration in adult newts, Triturus viridescens.

This experiment was designed to study the effect of optic nerve denervation on lens regeneration. Adult newts, Triturus viridescens, were divided into 4 groups: A) lentectomized newts, which served as controls, B) lentectomized newts with the optic nerve exposed and lightly palpated, C) newts with lens removed and the optic nerve cut simultaneously, and D) newts with lens removed first and optic nerve cut 7 days and 14 days later. Control animals required about 21 days to produce a new lens, and animals in group B demonstrated the same regeneration rate. In groups C and D, the regeneration rate was greatly retarded during the first 14 days. However, most of these animals regenerated a perfect new lens by 21 days postlentectomy.

Animals↗
PubMed1987

A Golgi study of the cerebral cortex in Fukuyama-type congenital muscular dystrophy, Walker-type "lissencephaly," and classical lissencephaly.

The cortical neuronal organization of the brain was studied and compared in three conditions. The neurons in the polymicrogyric cortex from a subject with Fukuyama-type congenital muscular dystrophy and from a child with ocular dysplasia (Walker-type lissencephaly) were large, irregularly aligned, and not completely mature. In the former condition, the abnormal neuronal arrangement was predominantly in the superficial cortex; in the latter both the superficial and deep cortex were involved. These two diseases may have a similar pathogenetic mechanism. In classical lissencephaly without evidence of other disease manifestations, the neurons were arranged in a radial pattern with heterotopia but no large neurons. The pathogenesis of these conditions is discussed.

Cerebral Cortex↗
PubMed1987

Diagnostic validity of the McCarron-Dial System in neuropsychological rehabilitation assessment.

The purpose of this study was to investigate the diagnostic validity of a neuropsychologically-based vocational evaluation battery, the McCarron-Dial System (MDS), in differentiating between brain-damaged and non-brain-damaged rehabilitation clients. Multiple discriminant analysis results indicate that 89% of the subjects were correctly classified. The results tentatively support the validity of the MDS for neurobehavioral diagnosis. However, additional emotional and behavioral information may be needed to increase classification accuracy and to determine more specific diagnosis. Because of its long tradition in vocational rehabilitation and established strengths in predicting vocational and community adjustment outcomes, the MDS may be potentially useful for both vocational and clinical neuropsychological assessment.

Adolescent↗
PubMed1986

Dendritic atrophy in children with Down's syndrome.

Dendritic branching was evaluated in the visual cortex of 8 children with Down's syndrome and 10 controls, ranging in age from 4 months to 7 years and divided into infantile, late-infantile, and juvenile groups. Camera lucida drawings of Golgi-impregnated neurons were used for examining the following dendritic aspects: dendritic intersections as a function of distance from the cell body, point of maximum dendritic branching, number of branch orders, total number of branch segments, and total dendritic length. The number of intersections and the total dendritic length were above normal in the infantile period (6 months old or less) and dropped steadily to significantly below normal in the juvenile group (older than 2 years). These reductions contrasted with expanding dendritic arborization in normal children. The results suggest that the dendritic tree atrophies in early childhood in Down's syndrome.

Child, Preschool↗
PubMed1986

Stereotyping. Physical and occupational therapists characterize themselves and each other.

Physical therapists (n = 53) and occupational therapists (n = 53) appraised themselves and each other by selecting personal and job-based adjectives (54 pairs) on the Health Team Stereotype Scale. The PTs' self-appraisal differed statistically from the OTs' perception of PTs on 31 adjective pairs (57%). The OTs judged PTs as having fewer of the qualities PTs professed on 16 pairs. On 15 pairs, the OTs chose negative adjectives, whereas the PTs chose the positive. The OTs' self-assessment differed statistically from the PTs' perception of OTs on 24 pairs. The PTs perceived OTs as having fewer of the positive adjectives than did the OTs. The PTs' and OTs' self-assessments differed statistically on pairs such as Strong-Weak, Intelligent-Unintelligent, and Aggressive-Passive, with the PTs' mean scores being higher than the OTs'. Overall, the PTs' self-appraisal mean scores were higher than the OTs'. The extent of differences perceived by another profession may explain team conflict or team effectiveness.

Attitude of Health Personnel↗
PubMed1986

The Street Survival Skills Questionnaire: a correlational study.

The appropriateness of the Street Survival Skills Questionnaire as a specific adaptive behavior measure for independent living was examined. The questionnaire was administered to 55 mentally retarded adults, along with Part I of the Public School Version of the Adaptive Behavior Scale and the Wechsler Adult Intelligence Scale. In addition, three of the subtests of the questionnaire were "operationalized," using actual stimulus materials such as tools, clocks, and money instead of the photographs used in the standardized version of the test. High significant correlations were observed among the questionnaire, the Adaptive Behavior Scale, and the operationalized versions of the Tools, Time, and Money subtests. Results support the appropriateness of this questionnaire as a measure of specific adaptive behavior.

Activities of Daily Living↗
PubMed1984

Dendritic development in human occipital cortical neurons.

Using quantitative techniques on rapid Golgi impregnations, the dendrites from neurons of visual cortex from 14 infants ranging in age from 20 weeks gestation to 7 years were assessed. Neurons in layers 3 and 5 were separately evaluated. The total dendritic length for all dendritic branches reached a maximum of 2800 microns for layer 3 neurons and 3400 microns for layer 5 neurons. At or before 40 weeks gestation, the dendritic tree of layer 3 neurons had reached 35% of the maximum compared with 55% of the maximum for layer 5 neurons. Dendritic branching occurred earlier in layer 5 and growth continued to be more advanced than in layer 3. After 40 weeks gestation in these layers no new branch orders were added to basal dendrites but 3 branch orders were added to apical dendrites. The determination of normal values for dendritic length, number of orders, and number of branches during early development provides a foundation for comparison of dendritic maturation in children with a variety of neurologic disorders.

Child↗
PubMed1982

Comparison of lens regeneration in adult newts, Triturus viridescens, between light and dark preadapted and non-preadapted animals.

It is well known that if the original lens is removed from the eyeball in certain Urodeles, a new lens will regenerate from the dorsal iris. Experiments were designed to study the different effects on lens regeneration in the newt, Triturus viridescens, between the light and dark preadapted animals and light and dark non-preadapted animals. The preadapted animals were preadapted to continuous light or dark for 90 days prior to lentectomy. The newts remained in the same controlled environments postlentectomy for 25 days to test the effect of light preadaptation on lens regeneration. The non-preadapted animals were placed in the light controlled environment immediately after lentectomy for a 25-day regeneration period. The results indicated that there was no difference in the rate of regeneration between continuous light preadapted and non preadapted animals. However, the dark non-preadapted animals regenerated new lenses at a much slower rate than the dark preadapted animals. The rate of lens regeneration was similar among the controls with 12 hours of light per 24-hour period, the dark preadapted, the continuous light preadapted, and continuous light non-preadapted groups.

Adaptation, Physiological↗
PubMed1982

Enzyme immunoassay of gentamicin with the Abbott ABA-100 analyzer.

The enzyme immunoassay of gentamicin using "EMIT" reagents was adapted to take advantage of the small reagent volume required by the Abbott ABA-100. The method increases fourfold the maximum number of tests per kit. The correlation with the bacterial inhibition method was 98%.

Autoanalysis↗
PubMed1981

Abnormal neuronal development in the visual cortex of the human fetus and infant with down's syndrome. A quantitative and qualitative Golgi study.

The developmental morphology of visual cortical neurons (their numbers, dendritic arborization and numbers of spines) in 14 fetuses and infants with Down's syndrome were studied and compared with that of neurologically normal, age-matched controls. Fetuses with Trisomy 21 showed the same neuronal morphology and spine counts as control fetuses. However, the newborns and older infants with Down's syndrome showed shorter basilar dendrites and decreased numbers of spines with altered morphology and defective cortical layering.

Age Factors↗
PubMed1981

Hormonal induction of pulmonary maturation in the rabbit fetus: effects of maternal treatment with estradiol-17 beta on th endogenous levels of cholinephosphate, CDP-choline and phosphatidylcholine.

1. Administration of estradiol-17 beta to pregnant rabbits at 25 days gestation (term, 31 days) resulted n a significant increase in the incorporation of [14C]-choline, but not [14C]ethanolamine, into the lipids of fetal lung slices. The incorporation of [35S]methionine was not affected. 2. Enzymatic assays conducted in vitro revealed no significant effect on either the activities of several enzyme markers for subcellular organelles, the activities of the enzymes responsible for the production of phosphatidylglycerol and phosphatidylinositol, membrane-bound or aqueously dispersed phosphatidate-dependent phosphatidic acid phosphohydrolase activities or the activities of the auxiliary enzymes responsible for the synthesis of dipalmitoylphosphatidylcholine. 3. The activity of the enzymes involved in the choline pathway for the de novo biosynthesis of phosphatidylcholine were not significantly altered except for a 66% increase in the CTP:cholinephosphate cytidylyltransferase activity assayed in the cytosol. The addition of phosphatidylglycerol stimulated cholinephosphate cytidylyltransferase activity approx. 3-fold. However, in the presence of this lipid, the activities in cytosol from control and treated fetuses were similar, indicating that the increased activity noted in the absence of phosphatidylglycerol was due to an activation of existing cytidylyltransferase activity rather than an increase in total enzyme units. 4. Estrogen treatment of the does was also associated with a marked decrease in the levels of cholinephosphate in fetal lung and significant increases in the levels of CDPcholine and phosphatidylcholine. These alterations in pool size are consistent with an increase in the activity of cholinephosphate cytidyltransferase in vivo. The results suggest that cholinephosphate cytidylyltransferase may catalyse an important rate-determining reaction in the synthesis of phosphatidylcholine in fetal lung. The data also support the view that the reaction catalysed by CDPcholine:diacylglycerol cholinephosphotransferase also has a regulatory role during development.

Animals↗