Biomedical subjects
Publications and source records attributed to F Chan.
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%.
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.
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.
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A renaissance of the Golgi impregnation method has focused interest on dendritic aspects of neuronal development. The visual cortices of 39 "neurologically normal" infants from 14 weeks' gestation to 6 months of age were prepared at postmortem for rapid Golgi impregnation studies. These were stained and duplicated with camera lucida drawings. The total number of cells in defined columns of the visual cortex was counted on cresyl violet-stained sections, and differentiated neurons were identified. The number of spines on the apical and basal dendrites of selected cells was counted for a given interval along the dendrites. The camera lucida drawings, cell counts, and spine counts were used to illustrate the normal ontogeny of the visual cortex.
Antisera made to prototype serogroup B strains of Neisseria meningitidis were used to serotype, by agar gel double diffusion, 262 meningococcal serogroups B and C strains isolated in Canada. The strains included 93 from patients and 169 from carriers. Serotype 2 was associated with 39 of 75 (52%) of group B strains and 14 of 18 (77.8%) of group C strains isolated from patients. The group B strains were mainly (87.2%) serotype 2b, while the majority (92.2%) of group C strains was serotype 2a. Other serotypes (including a new provisional serotype) represented 25.3 and 5.5% of groups B and C strains, respectively. The new serotype accounted for 13% of the group B strains. Approximately 23% of the strains isolated from patients were nontypable. The distribution of serotype 2, nontype 2 (other serotypes), and nontypable strains isolated from carriers was 2.1, 36.6, and 61.3%, respectively, for group B meningococci and 22.2, 29.6, and 48.25, respectively, for group C meningococci. Serotype 11 was the most prominent of the strains isolated from carriers. Approximately 7% of all the strains were multiple serotypes. Serotype 2 is an important virulence marker associated with meningococcal groups B and C disease in Canada, with serotypes 2a and 2b being markedly associated with groups C and B meningococcal disease, respectively.
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.
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.
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.
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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.
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.
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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.
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.
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.
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.