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Biomedical subjects

F Chan

Publications and source records attributed to F Chan.

88 records · Page 5Linked to original sources
PubMed1980

The effect of prolonged light and dark adaptation on lens regeneration in the adult newt Triturus viridescens.

Light intensity has been shown to affect lens regeneration in adult newts. Experiments were designed to study the effects of different light controlled environments on lens regeneration in the newt T, viridescens. Animals were preadapted to three light conditions: control, light from below and dark for ninety (90) days prior to lentectomy. The newts remained in the controlled environments post-lentectomy to test the effects of light preadaptation on lens regeneration. The results indicate that controlled light sources from below cannot stimulate the ventral iris to regenerate a new lens or inhibit the dorsal iris from normal lens regeneration. Lens regeneration in preadapted dark animals is similar in rate and amount to the control group indicating a totally dark environment does not always inhibit lens regeneration.

Adaptation, Ocular↗
PubMed1979

Glucocorticoid induction of pulmonary maturation in the rabbit fetus. The effect of maternal injection of betamethasone on the activity of enzymes in fetal lung.

1. Maternal administration of betamethasone (0.2 mg/kg) on day 25 or 26 of gestation produced a significant decrease in the lung/body weight ratio of the rabbit fetuses within 24 h. 2. The incorporation of [14C]choline but not [14C]ethanolamine into the lipids of fetal lung slices was significantly increased, indicating that there was a specific effect on phosphatidylcholine synthesis. 3. The activities of a number of marker enzymes for subcellular organelles were elevated, especially in the lungs of fetuses delivered on day 26. The increases in monoamine oxidase (mitochondrial outer membrane), beta-glycerophosphatase and aqueously dispersed phosphatidic acid-dependent phosphatidic acid phosphohydrolase (lysosomal) activities were significant. 4. Although the activity of cholinephosphotransferase was not affected by glucocorticoid treatment, the activities of glycerol-3-phosphate phosphatidyltransferase and the activities of two enzymes in the auxiliary pathways for the production of disaturated phosphatidylcholine (lysophosphatidylcholine:lysophosphatidylcholine transacylase and lysophosphatidylcholine:acyl-CoA acyl-transferase) were significantly increased. 5. Membrane-bound phosphatidic acid-dependent phosphatidic acid phosphohydrolase activity was elevated to a lesser extent than the aqueously dispersed phosphatidate-dependent activity and this increase was not significant. 6. The incorporation of E135S]methionine into protein by slices of fetal lung was significantly reduced after maternal treatment with betamethosone. 7. These results are consistent with the general view that glucocorticoids can induce pulmonary maturation and surfactant production in the rabbit fetus but indicate that some of the former hypotheses regarding the mechanism by which lipid synthesis is accelerated must be reevaluated.

Animals↗
PubMed1977

Bordetella pertussis in the National Capital Region: prevalent serotype and immunization status of patients.

Over a 2-year period 67 strains of Bordetella pertussis were identified in 231 single specimens of nasopharyngeal secretions submitted from patients suspected to have whooping cough in the National Capital Region; 89.5% of the identifications were made by culture. Serotype 1,3 was predominant. At least 75% of the patients with bacteriologically confirmed whooping cough had not been fully immunized. There was no evidence that adenoviruses or other viruses played any important etiologic role in the 204 cases of whooping cough or whooping cough syndrome studied virologically.

Bordetella pertussis↗
PubMedDate not supplied

Aberrant neuronal development in hemimegalencephaly: immunohistochemical and Golgi studies.

Immunohistochemical and Golgi studies were performed on 6 patients with hemimegalencephaly. Immunohistochemical staining demonstrated glial, neuronal, and myelin heterotopia in the leptomeninges, cortex, and white matter with glial fibrillary acidic protein, myelin basic protein, and synaptophysin antisera. Golgi studies revealed small and deformed neurons in the superficial layers around abnormal sulci, and hypertrophic neurons with an increased number of dendrites and spines in the deeper cortex. The coexistence of a cell migration disorder, proliferation, and hypertrophy in each patient may imply a growth factor disturbance that controls cell proliferation. These unilateral cerebral malformations suggest that early surgical excision may be beneficial.

Astrocytes↗
PubMedDate not supplied

Abnormal dendritic development in maple syrup urine disease.

The neuropathology of a 6-year-old boy with maple syrup urine disease revealed spongy appearance of the white matter and marked edema of the brainstem. Golgi studies demonstrated aberrant orientation of neurons together with abnormalities of dendrites and dendritic spines. Similar changes were observed in a patient with dihydropteridine reductase deficiency. Disorders of amino acid metabolism may be associated with alterations in the terminal stages of neuronal migration and maturation.

Brain↗
PubMedDate not supplied

Valve replacement surgery complicated by acute renal failure--predictors of early mortality.

BACKGROUND: Acute renal failure (ARF) is a serious complication of valve replacement surgery. The aim of this study was to determine the predictors of early mortality and if causative factors are preventable. METHODS: In the 25-year period between 1977 and 2002, 255 (2.6%) of 9721 patients (11,007 operations), who had valve replacement surgery, were managed for ARF with dialysis. The mean age of the patient population was 67.1 +/- 11.6 years (range 24 to 87 years, median 70.3 years). Fifty preoperative, operative, and postoperative risk factors were assessed as predictors of early mortality by univariate and multivariate modeling. RESULTS: The early mortality was 25.1% (64 patients). The predictors by univariate analysis were: New York Heart Association class (p = 0.001); ASA within 5 days (p = 0.030); cardiogenic shock (p = 0.010); infection--perioperative sepsis and preoperative endocarditis (p = 0.000); intraoperative stroke (p = 0.003); status--emergent (p = 0.000); mitral valve replacement (p = 0.040); ischemic (X-clamp) time >120 minutes (p = 0.020); cardiopulmonary bypass time >180 minutes (p = 0.000); surgical time >360 minutes (p = 0.000); surgical hemorrhage (p = 0.020); acute respiratory distress syndrome (ARDS) (p = 0.040). Multivariate predictors were urgent status of operation, odds ratio (OR) 0.3 (p = 0.029); emergent status of operation, OR 5.8 (p = 0.034); ischemic (X-clamp) time >120 minutes, OR 4.4 (p = 0.030); surgical time >360 minutes, OR 6.3 (p = 0.019); surgical hemorrhage, OR 5.1 (p = 0.003); perioperative nosocomial sepsis, OR 3.8 (p = 0.006); and preoperative endocarditis, OR 4.4 (p = 0.004). CONCLUSIONS: Early mortality from ARF in valve replacement surgery is related to emergent status, ischemic and surgical times, surgical hemorrhage, and nosocomial infection/preoperative endocarditis. Among the variables assessed, preoperative renal insufficiency, unstable angina/recent myocardial infarction <6 weeks, and concomitant coronary artery bypass were not predictive. The evaluation of predictors of ARF requires further extensive assessment.

Acute Kidney Injury↗
PubMedDate not supplied

Cellular distribution of enzymes involved in phosphatidylcholine synthesis in developing rat lung.

The incorporation of radioactive choline into phosphatidylcholine and disaturated phosphatidylcholine in rat lung slices increased markedly before term and peaked after birth. The specific activity of cholinephosphate cytidylyltransferase in the microsomal fraction increased before birth but fell after delivery. The specific activity of this enzyme in the cytosol showed a marked increased at birth. The developmental profile for the total cytosolic activity per gram lung was similar to the pattern observed with choline incorporation. Although the specific activity of cholinephosphotransferase in the whole homogenate remained relatively constant throughout pulmonary maturation, there was a marked increase in the specific activity of this enzyme in the microsomal fraction at term. Similar findings were obtained with the microsomal marker NADPH-cytochrome c reductase. The basis of this disparity in specific activity profiles is being investigated further. The specific activity of lysophosphatidylcholine:lysophosphatidylcholine transacylase in rat lung homogenates increased during gestation but rose a further 10-fold between day 3 after birth and the adult. The specific activity of lysophosphatidylcholine:palmitoyl-CoA acyltransferase remained relatively constant throughout development. At term, the specific activity of the acylation enzyme was 10- to 15-fold greater than the specific activity of the transacylation enzyme. These observations are consistent with previous studies indicating that the accumulation of phosphatidylcholine and dipalmitoyl phosphatidylcholine during the perinatal period may be due to alterations in the activity of cholinephosphate cytidylyltransferase. Cholinephosphotransferase could also play a regulatory role. The formation of dipalmitoyl phosphatidylcholine appears to occur via the acylation, rather than the transacylation pathway.

1-Acylglycerophosphocholine O-Acyltransferase↗
PubMedDate not supplied

Neuropsychological assessment of brain damage: discriminative validity of the McCarron-Dial System.

The purpose of this study was to investigate the discriminative validity of the McCarron-Dial System (MDS) in neuropsychological assessment. Multiple discriminant analysis results indicate that 92.6% of the brain-damaged and non-brain-damaged groups, and 69.6% of the right, left and diffused brain-damaged subgroups were correctly classified using the abbreviated version of the MDS. The results tentatively support the discriminative ability of the MDS for neurobehavioural diagnosis. Since the MDS has a long tradition in vocational rehabilitation and established strengths in predicting vocational and community adjustment outcomes, it may be potentially useful for both vocational and clinical neuropsychological assessment.

Adolescent↗
PubMedDate not supplied

Cortical dysgenesis in a variant of phenylketonuria (dihydropteridine reductase deficiency).

The neuropathology of a 2 1/2-year-old patient with dihydropteridine reductase deficiency showed diffuse demyelination throughout white matter and spongy vacuolation in the long tracts of the brain stem. These changes are characteristic neuropathologic observations in untreated phenylketonuria. In addition, extensive neuronal loss, calcification and abnormal vascular proliferation were noted in the cerebral cortex, white matter, basal ganglia, and thalamus. Golgi studies demonstrated an abnormal orientation of neurons together with abnormalities of dendrites and dendritic spines. The pathogenesis of the vascular abnormalities in this condition is unknown, although folate deficiency may be involved. The secondary deficiency of serotonin and dopamine occurring during neuronal growth and differentiation may also affect the terminal stages of neuronal maturation.

Cerebral Cortex↗
PubMedDate not supplied

Cultural perspectives in caring for Chinese renal patients.

The meaning of the human body, concept of health and illness, beliefs in diet, languages, and family structure all have impact on the planning of nursing interventions in caring for patients. This article focuses on the impact of the above variables on Chinese patients who have renal disease. Suggestions are given in caring for this particular group of Chinese patients.

Canada↗
PubMedDate not supplied

Prestige: radiologic technologists rate themselves and other allied health professionals.

This study investigated radiologic technologists' (RTs) prestige ratings of 13 allied health professions and 13 general occupations selected from the original National Opinion Research Center (NORC) list. RTs ranked themselves fifth and on the whole tended to elevate the ratings of the allied health professions. There was a high degree of agreement between RTs' ratings and the NORC occupations data. Implications for the RT profession and for future research are noted.

Allied Health Personnel↗
PubMedDate not supplied

Aberrant dendritic development in the human agyric cortex: a quantitative and qualitative Golgi study of two cases.

A quantitative and qualitative Golgi comparison of the visual cortex from two agyric brains and of two age-matched controls is reported. In the camera lucida drawings, most pyramidal cells were oriented vertically to the pial surface in the external cellular layer, frequently with their apical dendrites directed toward the deep layers (inverted pyramidal neurons). The deep cellular layer contained pyramidal and polymorphic neurons normally found in the second to fourth cortical layers. In quantitative analysis of the agyric cortex of a ten-month-old patient, relative immaturity of basal dendritic arborization was apparent together with a bipolar configuration of dendritic development of the pyramidal neurons. The 3-year-old patient had a significant delay in apical dendritic arborization (shorter branch length, decreased number of dendritic intersections) compared with his age-matched normal control. The pathogenesis of the abnormal dendritic development in agyria is discussed.

Cerebral Cortex↗
PubMedDate not supplied

Prestige of radiologic technologists: perception of two allied health professions.

Physical and Occupational Therapists in large urban hospitals rated the prestige of 13 allied health professions, generally hospital based. Radiologic Technologist was ranked 13th by PTs and 12th by OTs. PTs were more negative with 35% using ratings below "average," while OTs assigned 28%. Only 27% of the PTs used ratings above "average," while 33% of the OTs did so. Prestige scores derived for Radiologic Technologists placed them among nonprofessionals.

Attitude of Health Personnel↗