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Biomedical subjects

V Wong

Publications and source records attributed to V Wong.

At least 145 records · Page 8Linked to original sources
PubMed1989

A randomized study of high-dose versus low-dose cis-platinum combined with cyclophosphamide in the treatment of advanced ovarian cancer. Hong Kong Ovarian Carcinoma Study Group.

A randomized clinical study of patients with advanced epithelial ovarian cancer after debulking surgery showed that high-dose (120 mg/m2) cis-platinum (DDP) in combination with cyclophosphamide (600 mg/m2) had a significantly higher response and survival rate than the low-dose DDP (60 mg/m2) and cyclophosphamide combination. The 3-year actuarial survival rate of the high-dose group was 60% and that of the low-dose group was 30%. Though moderate to severe marrow toxicity was evident in 80% of the patients in the high-dose group and 40% of the low-dose group, no serious sepsis or death developed as a result of the marrow depression. Mild neurotoxicity was observed in 55% of the patients in the high-dose group and only 20% in the low-dose group. Mild nephrotoxicity was seen in 25 and 17% of patients in the high- and low-dose groups, respectively. It was concluded that the 120 mg/m2 dose DDP and cyclophosphamide combination should be used in the treatment of carcinoma of the ovary in spite of its toxicities. However, it should only be used in institutions with supportive facilities in the management of patients with severe marrow depression.

Adolescent↗
PubMed1989

Possible evidence for a variant of myasthenia gravis based on HLA and acetylcholine receptor antibody in Chinese patients.

A comprehensive study of 194 Chinese patients with myasthenia gravis in Hong Kong has shown distinct differences from the patterns of disease seen in Caucasians. Restricted ocular myasthenia is the predominant disease type in patients presenting in the first two decades of life and is associated with absence or low titres of acetylcholine receptor antibody. Predisposition to this type of disease is strongly associated with HLA-DRw9. Generalized myasthenia gravis occurs predominantly in patients presenting after the age of 20 years and is accompanied by high titres of acetylcholine receptor antibody but is less strongly associated with HLA-DRw9. It is suggested that myasthenia gravis occurring within the first two decades of life and characterized by affected ocular muscles and absence or low titre of acetylcholine receptor antibody is a genetically determined variant of the disease which occurs commonly in Orientals.

Adult↗
PubMed1987

Distribution of carbonic anhydrase activity in neurons of the rat.

Certain neurons of dorsal root ganglia (DRG) and some fibers of the sciatic nerve contain histochemically demonstrable carbonic anhydrase activity. Since the distribution of this enzyme throughout the nervous system has not yet been evaluated systematically, we conducted a comprehensive histochemical survey focusing particularly on structures derived from the neural crest and nonneural crest ectoderm. In the peripheral nervous system, we observed carbonic anhydrase activity in some, but not all, neurons of dorsal root, trigeminal, celiac, and myenteric ganglia as well as in glial cells throughout the CNS. Some neurons of the nodose ganglion also showed carbonic anhydrase activity. In all first order sensory ganglia that were studied, the enzyme was found only in large (50 micron or above) and medium (20-50 micron) size neurons; in the case of spinal ganglia, the reactive neurons constituted approximately 30% of the total neuronal population. Of these reactive neurons, 56% were heavily stained and 44% were moderately stained. Several possible roles for neuronal carbonic anhydrase are considered.

Animals↗
PubMed1987

Ataxia telangiectasia in Chinese children. A clinical and electrophysiological study.

The clinical manifestations, immunological, chromosomal, and multimodal electrophysiological studies of five Chinese patients with ataxia telangiectasia are described. One died of hepatocellular carcinoma not associated with Hepatitis B-antigenaemia. Another died of respiratory failure. Two siblings are free of sinopulmonary infections although they are wheelchair bound. Computed tomography of the brain showed cerebellar atrophy in four cases. Nerve conduction studies showed evidence of axonal neuropathy in all cases with the earliest detection at six years. Electromyography showed mild denervation changes in two cases. Two patients had abnormal somatosensory evoked potentials and one had abnormal visual and brain stem auditory evoked potentials. The level of alpha foetal protein was elevated whereas the serum carcino-embryonic antigen was normal in all patients.

Adolescent↗
PubMed1987

Solubilization of a membrane factor that stimulates levels of substance P and choline acetyltransferase in sympathetic neurons.

The choice of which neurotransmitters will be produced by a developing neuron is influenced by the microenvironment of the neuron. In this study we show that neuronal contact with membrane-associated molecules promotes expression of peptidergic and cholinergic traits. Treatment of cultured neonatal rat sympathetic neurons with plasma membranes derived from adult rat spinal cord or sympathetic ganglia induced expression of the peptide transmitter substance P and increased levels of the cholinergic biosynthetic enzyme choline acetyltransferase. The transmitter-stimulating activity could be solubilized from spinal cord membranes by the detergent octyl glucoside but not by Triton X-100. The choline acetyltransferase- and substance P-stimulating activity also could be extracted from spinal cord membranes by 4 M sodium chloride, suggesting that the active material is membrane associated rather than an intrinsic structural membrane molecule. Trypsin or heat treatment of the extract destroyed the transmitter-stimulating activity, indicating that the factor contains a protein. Activity also was destroyed by hyaluronidase treatment, suggesting that the active material may contain a glycosaminoglycan. The choline acetyltransferase-stimulating activity in the 4 M NaCl extract was eluted in a single peak from a calibrated Sephadex G-75 column with a retention time slightly less than that of a 25-kDa standard. NaDodSO4/polyacrylamide gel electrophoresis of the active peak revealed a predominant band at 29 kDa. Thus, contact-mediated stimulation of substance P and choline acetyltransferase activity in sympathetic neurons results from neuronal exposure to a 29-kDa membrane-associated factor.

Animals↗
PubMed1987

Acute viral encephalitis in children.

Fifty-seven cases satisfying criteria of the diagnosis of acute viral encephalitis were studied. They were divided into two groups: Group 1 (presumed), 48 cases; Group 2 (postinfectious), nine cases. A possible association of viral aetiology was found in 26%. Viruses isolated were: influenza (3 cases), Coxsackie virus (2), adenovirus (2), mixed cytomegalovirus and adenovirus and herpes simplex viruses (1 case each). The mortality rate was 28%. Among the 41 survivors, 76% were completely normal and 24% had neurological sequelae with focal neurological deficit in 29%; personality changes in 6%; moderate mental retardation in 2%; severe mental retardation in 4%; hyperactivity in 4% and epilepsy in 4%. The best predictors to unfavourable outcome were the rapid rate of deterioration in conscious level after admission and the age of the patients.

Acute Disease↗
PubMed1987

Dystrophia myotonica and pregnancy--an instructive case.

Two cases of dystrophia myotonica, a mother and her newborn child, are reported. The diagnosis in the mother was only made after seven years and two eventful deliveries. The obstetrical and anaesthetic complications, as well as the neonatal form of dystrophia myotonica, are reviewed.

Adult↗
PubMed1985

Zinc deficiency is not a cause for abortion, congenital abnormality and small-for-gestational age infant in Chinese women.

Zinc concentration in serum and hair was measured in a cross-sectional study of 437 Chinese women of whom 310 were normal controls studied at various stages of pregnancy and up to 12 months after delivery. The rest had spontaneous abortions, fetuses with a birthweight below the 10th centile for gestation or congenital abnormalities. Zinc concentration fell throughout normal pregnancy, the fall being greater in serum than in hair. There was no correlation between serum and hair levels. The infant birthweight had a positive correlation with serum level but a negative correlation with hair level. Abortion, low birthweight and congenital abnormality were not associated with low concentrations of zinc in plasma or hair.

Abortion, Spontaneous↗
PubMed1985

A study of the adhesive, locomotory and invasive behaviour of Walker 256 carcinosarcoma cells.

We have succeeded in selecting two variant strains of the Walker 256 carcinosarcoma which display markedly different adhesive properties. Both the high (W256A) and the low (W256S) adhesive variants respond chemotactically towards 10(-8) M f-met-leu-phe (FMLP) although there is a significant difference in their locomotory ability. Nevertheless, the fact that the essentially non-adherent W256S cells can migrate in vitro argues against any simple relationship between adhesion and locomotion. We suggest that traction is important in locomotion but that it need not arise only from direct adhesive interaction. We have also tested the invasive behaviour of the W256 variants using an in vitro model system in which disruption of a cellular barrier by the invasive cells can be recorded electrophysiologically. Although leucocytes can penetrate such a barrier they do so only under chemotactic stimulation, whereas W256 tumour cells of either variant strain will do so spontaneously. The tumour variants induce cell retraction within the barrier and this may lead ultimately to cell detachment and death. The holes which arise may then be colonized by tumour cells, and in this way the invasive process could be promoted. The molecular mechanisms by which tumour cells achieve destruction of the cellular barrier are not clear, but it is likely that a number of enzymes are involved.

Animals↗
PubMed1985

In vitro characteristics of pulmonary neuroendocrine cells isolated from rabbit fetal lung. I. Effects of culture media and nerve growth factor.

Pulmonary neuroendocrine (NE) cells, dispersed throughout the airway mucosa as single cells and as innervated clusters (neuroepithelial bodies), were isolated from rabbit fetal lung and studied in short-term culture. The effects of culture media and nerve growth factor (NGF) on in vitro maintenance, differentation, and cell kinetics of isolated NE cells were examined. For demonstration of NE cells in intact lung, during cell separation and after culture, immunostaining for serotonin, formaldehyde-induced fluorescence method, histochemical reaction for acetylcholinesterase, and electron microscopy were used. The isolation procedure consisted of mechanical and enzymatic dissociation of lung tissue followed by separation of isolated cells on a discontinuous gradient of Percoll, resulting in 5- to 10-fold enrichment in NE cells. Cell fractions enriched in NE cells were cultured up to 7 days either in supplemented alpha-minimal essential medium with fetal bovine serum or in defined, hormone-supplemented, serum-free medium. NGF (2.5 S 5 to 50 ng/ml) was added to both serum-supplemented and serum-free media; cultures without NGF served as control. The number of serotonin-immunoreactive NE cells maintained in serum-supplemented medium (0.5% fetal bovine serum) increased significantly (p less than 0.05) on days 4 and 7 compared with cultures grown in serum-free medium. NE cells maintained in serum-supplemented medium incorporated [3H]thymidine and their labeling index was significantly increased (p less than 0.01) on day 7, whereas few or no NE cells were labeled in cultures grown in serum-free medium. NGF had no effect on the maintenance or kinetics of NE cells. Cultured NE cells formed elongated (unipolar or bipolar) neurite-like cytoplasmic processes with a button-like ending, regardless of the presence of NGF. Amine accumulated in perinuclear cytoplasm and in button-like endings. Staining for acetylcholinesterase (strongly positive in intact neuroepithelial bodies) was not detectable after separation into single cells, culture, or exposure to NGF. This study demonstrates that NE cells can be isolated from rabbit fetal lung and maintained in short-term culture. Low concentrations of fetal bovine serum enhanced the in vitro maintenance of NE cells, whereas NGF had no such effect. A feeder layer may be also important, since NE cells were closely associated with lung epithelial or fibroblast-like cells. The formation of neurite-like processes appears to be an expression of paracrine/paraneuron-type cell differentiation not mediated by NGF.(ABSTRACT TRUNCATED AT 400 WORDS)

APUD Cells↗
PubMed1984

Chorismate mutase/prephenate dehydrogenase from Escherichia coli K12: purification, characterization, and identification of a reactive cysteine.

The bifunctional enzyme involved in tyrosine biosynthesis, chorismate mutase/prephenate dehydrogenase, has been isolated from extracts of a regulatory mutant of Escherichia coli K12. The pure enzyme is a homodimer of total molecular weight 78 000 and displays Michaelis-Menten kinetics for both activities. Fingerprinting and amino acid sequencing of tryptic and thermolytic peptides of the S-[14C]carboxymethylated enzyme allowed the identification of three unique cysteine-containing sequences per subunit. Chemical modification of the native enzyme with 5,5'-dithiobis(2-nitrobenzoate) or iodoacetamide showed that one sulfhydryl group per subunit was particularly reactive, and the integrity of this group was essential for both enzymic activities. This work supports previous proposals for a close spatial relationship between the active sites.

Amino Acid Sequence↗
PubMed1984

Abdominal circumference vs abdominal area--which is better?

The efficacies of ultrasonic abdominal circumference (AC) and abdominal area (AA) measurements in the evaluation of intrauterine fetal growth were compared. The intraobserver random and technical errors were found to be significantly higher with AA measurements. The correlation with intrauterine fetal weight was observed to be better with AC as compared with AA measurements, the fetal weights being expressed as either linear regressions or multiple regressions involving the two parameters. Between 32 and 38 weeks, a single AC measurement detects 74 per cent of small-for-date fetuses, while a single AA measurement detects only 58 per cent of such fetuses. The false-positive rates were similar for the two parameters. It is concluded that AA measurements are no more useful than AC measurements in the routine assessment of intrauterine fetal growth.

Abdomen↗
PubMed1983

Three-dimensional reconstruction of a rat stage V Sertoli cell: I. Methods, basic configuration, and dimensions.

A model of a rat stage V Sertoli cell was reconstructed from semiserial sections. Seventy-five montages were made from 96 grids that supported the 223 sections needed to traverse the reconstructed cell. Section thickness (184.6 nm) and spacing of sections were calculated based on the diameter of spherical germ cell nuclei included within the sections. The outline of the cell border was traced on acetate sheets and from there traced on Plexiglas; then the Plexiglas was cut with a hot wire. The model, enlarged to a magnification of 7,800 times, was made from five parts that may be disassembled. The cell dimensions, as determined from the model, were 89.8 micron in the centripetal axis, 41.2 micron in the longitudinal axis, and 29.5 micron in the circumferential axis. The cell was irregularly columnar in shape with a base resting on the basal lamina and lateral surfaces in contact with adjacent Sertoli cells and round germ cells. Lateral processes were of three types: 1) conical processes extending from the lateral surface near its base; 2) cup-shaped, sheet-like processes partially encompassing round germ cells; and 3) flattened, sheet-like processes extending between round germ cells. Elongate spermatids occupied deep, irregularly shaped cylindrical recesses oriented in the centripetal axis of the Sertoli cell. The walls of the Sertoli cell forming these cylinders were thick basally and sheet-like and very thin near the lumen where they anastomosed and also composed the lateral walls of the cell. The tapered luminal extensions of the sheet-like, cylindrical processes were termed apical processes. The volume of the reconstructed cell was calculated to be 6,012 micron3. This study has provided the first unencumbered view of the external profile of a Sertoli cell. The model represents one of two major configurations that the Sertoli cell assumes during the spermatogenic cycle.

Animals↗
PubMed1983

Three-dimensional reconstruction of a rat stage V Sertoli cell: II. Morphometry of Sertoli--Sertoli and Sertoli--germ-cell relationships.

Sertoli--Sertoli and Sertoli--germ-cell configurational relationships were studied using morphometric techniques and direct measurements as obtained from micrographs used to reconstruct a model of a rat stage V Sertoli cell. Regional areas of the Sertoli cell surface, which faced germ cells, other Sertoli cells, or noncellular structures, were expressed as relative surface area percentages; and the absolute surface areas for these regional areas were calculated. The surface areas of the reconstructed cell, in its unmagnified state, was found to be 12,163 micron2. Cell processes were enumerated and studied using morphometric techniques. The surface area of the reconstructed Sertoli cell facing germ cells and Sertoli cells was also determined. Five Sertoli cells showed extensive contact with the reconstructed cell at the level of the Sertoli--Sertoli junctional contact region. This contact region averaged 3.51 micron in width. The relative and absolute surface area of subsurface ectoplasmic specialization of the Sertoli cell that faced germ cells and other Sertoli cells was calculated, and the extent of penetration of step 17 spermatids into the Sertoli crypts was determined. Surface relationships of the reconstructed cell to cellular and noncellular elements were depicted on outline drawings of the Sertoli cell.

Animals↗