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Biomedical subjects

V Wong

Publications and source records attributed to V Wong.

At least 163 records · Page 9Linked to original sources
PubMed1983

Three-dimensional reconstruction of a rat stage V Sertoli cell: III. A study of specific cellular relationships.

Specific Sertoli--Sertoli and Sertoli--germ-cell contacts and/or junctions were investigated employing micrographs used to reconstruct serially a model of a rat stage V Sertoli cell. The Sertoli--Sertoli junctional contact areas occurred in a belt-like arrangement near the base of the Sertoli cell. This configuration is consistent with their proposed function as a sealing element limiting the passage of materials toward the tubular lumen. Sertoli ectoplasmic specializations also formed a continuous belt, or band, around the reconstructed cell at the junctional contact area. Eighteen Sertoli--Sertoli tubulobulbar complexes were found; some (12 in number) invaginated the reconstructed cell, while others (6) emanated from it. Of 37 round germ cells that were sectioned in their entirety and adjoined the reconstructed cell, 23 displayed desmosome-gap junctions with either the reconstructed cell or an adjoining cell. Since there were multiple junctions connecting some germ cells to Sertoli cells, the total number of junctions was much greater (35). Desmosome-gap junctions of the Sertoli cell were numerous connecting pachytene spermatocytes, less numerous connecting type B spermatogonia, and even less numerous connecting step 5 spermatids; and none was seen joining Sertoli cells with elongate spermatids. Most desmosome-gap junctions join germ cells to the body of the Sertoli cell at its basal aspect. Their numbers and position indicate that they play a role in the maintenance of the integrity of the seminiferous epithelium and may provide a route for cell-to-cell communication. Ectoplasmic specializations of the reconstructed cell were seen facing only 3 of 37 round germ cells, and 7 ectoplasmic specializations from adjoining Sertoli cells faced these germ cells, all of which were step 5 spermatids. That there were no ectoplasmic specializations facing pachytene cells indicates that ectoplasmic specializations are not acquired as these cells pass through Sertoli--Sertoli junctions, but are acquired later in spermatogenesis.

Animals↗
PubMed1983

Left-right pairing at the crest synapses of rat interpeduncular nucleus.

Synaptic terminals of the habenulo-interpeduncular axons in rat interpeduncular nucleus are demonstrated by electron-microscopic autoradiography following [3H]leucine injection into the habenula. The endings are of two types, S and crest synapses. Previous descriptions of the S synapses based on indirect identification were confirmed. The crest synapses in the interpeduncular nucleus consist of two habenular afferents contacting a narrowed dendrite. Injection of both habenulae with radiolabeled amino acid resulted in autoradiographic labeling of both axons at 48% of individual crest synapses, and of one axon at 39%. However, when only one habenula was injected, no more than one axon was labeled at individual crest synapses; this occurred at 59%. Interpretation of unlabeled endings is possible using the "detection rate" of the method (per cent ratio of labeled to total endings). The detection rate, which can be determined for the bilateral injection case, allows recalculation of the raw data for the unilateral injection case. Left-right pairing of habenular afferents actually occurs at approximately 90% of crest synapses. The use of detection rates in this way, additionally exemplified by analysis of an electron-microscopic degeneration study, is also important in many other applications of both of these experimental neuroanatomical methods, especially when comparisons between two sets of data are made. The conclusions of studies which have not taken this problem into account must be interpreted with caution.

Afferent Pathways↗
PubMed1983

Term breech delivery--is a high Caesarean section rate justified?

The Caesarean section rate for breech presentation has fallen from 60% in 1978 to 38% in 1980 at the University teaching hospital in Hong Kong. The number of Caesarean sections carried out for the indication of "unfavourable pelvis' in 1980 was approximately half that in 1978. No significant difference in perinatal outcome was noted in the group delivered vaginally in these 2 years. It was concluded that a high Caesarean section rate in term breech presentation may not be justified in modern obstetric practice because of the associated increase in maternal morbidity. Many patients labelled as having an "unfavourable pelvis' can in fact have a safe vaginal breech delivery.

Adult↗
PubMed1982

The effect of oral contraceptives on coagulation and fibrinolytic parameters in the Chinese--a prospective study.

Thirty-two Chinese and 7 Caucasians were studied prospectively for 12 months for the effects of oral contraceptives (OC) on certain coagulation and fibrinolytic parameters. In both ethnic groups there was an increase in alpha 1 antitrypsin level. There was no significant change in antithrombin III concentration measured either by radioimmunoassay (At-III-RIA) or chromogenic assay (anti Xa-chromogenic) in the Chinese, but a significant decrease in anti Xa-chromogenic at 7 months and At-III-RIA at 12 months in the Caucasians. Also, alpha 2 plasmin inhibitor (alpha 2 PI) levels were unchanged in the Chinese but a significant increase occurred in the Caucasians at 12 months. Enhanced fibrinolytic response to venous occlusion was demonstrated in the Chinese at 12 months but not in the Caucasians.

Adult↗
PubMed1982

Flexure and residual astigmatism with Polycon and polymethyl methacrylate lenses on toric corneas.

Previous investigators have shown that thin polymethyl methacrylate (PMMA) contact lenses (less than or equal to 0.12 mm) flex on toric corneas, thereby altering the residual astigmatism. The present study was designed to evaluate the flexure and residual astigmatism of gas permeable Polycon contact lenses on toric corneas and compare the results with those obtained with PMMA lenses on the same corneas. Eight subjects (16 eyes) with corneal toricities ranging from 1.25 to 4.25 D wore four pairs of identical Polycon and PMMA lenses. The only lens parameter that varied was center thickness, which ranged from 0.07 to 0.16 mm. Flexure and residual astigmatism were measured on all corneas with all lenses in a double-masked fashion. Our results indicate that Polycon lenses undergo significantly more flexure and alter residual astigmatism more on toric corneas than PMMA lenses at all center thicknesses evaluated. For both materials, flexure and residual astigmatism increased as center thickness decreased. The clinical implications of these findings are discussed.

Adult↗
PubMed1980

Deep vein thrombosis and changes in coagulation and fibrinolysis after gynaecological operations in Chinese: the effect of oral contraceptives and malignant disease.

Of 154 Chinese patients who underwent gynaecological operations, four showed a positive 125I fibrinogen leg scan for venous thrombosis, and overall incidence of 2 . 6%. In those who were on oral contraceptives and had major pelvic surgery for benign conditions, the incidence was 10 . 5%; in those who had Wertheim hysterectomy for carcinoma of cervix, it was 6 . 7%. This confirms the rarity of post-operative thromboembolism in the Chinese. Fragment E showed a biphasic rise after major operation due to tissue injury and venous thrombosis. In patients with malignancy, the postoperative 'fibrinolytic shutdown', represented by decreased plasminogen activator together with increased alpha 1 antitrypsin and C1- inhibitor levels, was more marked. In addition, alpha 2 macroglobulin level was lower and fell significantly after operation. In patients on oral contraceptives, fragment E levels were higher after surgery and there was no decrease in plasminogen activator levels. Antithrombin III levels did not fall except in three of the four patients with venous thrombosis. A marked increase in fragment E level and a decrease in antithrombin III level might be useful diagnostic markers for postoperative venous thrombosis.

Asian People↗
PubMed1980

The effect of maternal cardiac disease and digotoxin administration on labour, fetal weight and maturity at birth.

One hundred and twenty-two patients with cardiac disease were compared with 250 controls with respect to the duration of pregnancy and labour, birth weight percentile and Apgar score. The babies of the patients with cardiac disease were light-for-dates (18% below the 10th percentile); the mothers, if multiparous, delivered at an earlier gestational age. The patients with cardiac disease did not have shorter labours than the control group. Digoxin administration and the severity of heart disease had no significant effect on these variables.

Apgar Score↗
PubMed1979

Neuro-epithelial bodies in organ cultures of fetal rabbit lungs. Ultrastructural characteristics and effects of drugs.

Lung explants from fetal rabbit at the late glandular stage of development (20 days' gestation) and near term (31 days' gestation) were maintained in organ culture for up to 22 days. They were studied by light and electron microscopy to determine whether neuro-epithelial bodies (NEB) of the lung retain structural integrity in vitro. Cultured NEB retained argyrophilia and specific amine fluorescence after formaldehyde condensation. Their ultrastructural morphology showed some differences from that of uncultured NEB: the terminal axons had degenerated and the secretory granules (dense-core vesicles, DCV) were slightly larger, more pleomorphic, more electron-dense, and redistributed throughout the cytoplasm rather than being confined chiefly to the basal regions. These changes, together with hypertrophy of Golgi zones, suggest increased synthesis and storage of secretory products in the DCV during culture. In NEB from near-term explants cultured for 7 days and incubated with reserpine, the core of DCV decreased in size and electron-density and became finely granular, a sign of amine release. Ca++ ionophore No. A-23187, also, induced changes in the ultrastructure of DCV, suggesting that the secretory process in lung neuro-endocrine cells, as in other secretory cells, is Ca++-dependent.

Animals↗
PubMed1979

Increased ejection fraction produced by a long-term subhypertensive infusion of norepinephrine in the conscious dog.

Five mongrel dogs with chronically implanted catheters in the left atrium, mid-thoracic aorta, and right atrium were continuously infused with subhypertensive doses of norepinephrine for 3 months. Left ventricular cineangiography, determinations of aortic pressure, and cardiac output were performed in the conscious dog. After 3 months of continuous norepinephrine infusion, stroke volume increased from 38 +/- 3.0 to 67 +/- 8.0 ml. (p less than .01), the left ventricular end-diastolic volume increased from 72 +/- 6.4 to 89 +/- 12.9 ml. (p less than .05), and the ejection fraction increased from 52 +/- 3.6 to 76 +/- 3.6% (p less than .005). We postulate that norepinephrine results in an increased myocardial function by producing physiological myocardial hypertrophy.

Animals↗
PubMed1979

The determination of antithrombin III by radioimmunoassay and its clinical application.

A radioimmunoassay (RIA) had been developed for the determination of antithrombin III (AT III) in man. The detection limit was 25 microgram/dl. AT III-RIA level and biological activity (anti-Xa) was significantly correlated (r = 0.737, P less than 0.001). Plasma levels in 36 healthy males (mean +/- SD, 19.9 +/- 2.5 mg/dl) and 21 healthy females (19.1 +/- 2.4 mg/dl) were similar. Serial AT III measurements in normal menstruating females showed lower levels during midcycle and higher concentrations during menstruation. In carcinomas, the AT III levels were lower than normal, particularly in hepatocellular carcinoma. In cirrhosis of liver, the levels were markedly decreased and in some patients were below that found in congenital AT III deficiency. Patients with deep vein thrombosis and patients with heart valve replacement had lower levels than normal, while patients with cerebral vascular occlusion had normal levels. The possible use of AT III as a diagnostic tool of post-operative deep vein thrombosis was demonstrated in one patient after hysterectomy. The increased sensitivity, specificity and precision of this type of assay offer distinct advantages over existing methods of AT III estimation.

Adult↗
PubMed1978

Transfer of digoxin across the placenta and into breast milk.

Eleven mothers given digoxin throughout pregnancy because of rheumatic heart disease were studied. Digoxin was identified in the placenta and, for the first time, in milk. Paired cord and maternal blood samples obtained at parturition showed lower digoxin levels in cord blood than in maternal blood. The total tissue-bound digoxin level in the placenta correlated closely with maternal digoxin levels. These findings suggest strongly the presence of a placental barrier for digoxin. Similar digoxin concentrations (0.825 +/- 0.015 nmol/l) were found in milk samples obtained daily between the third and seventh days post partum. The half-life of digoxin in the newborn was 36.2 +/- 5.43 hours (Mean +/- SEM); thus all the digoxin present at birth would be excreted within 10 to 11 days.

Adolescent↗
PubMed1976

Von Hippel-Lindau disease: clinical and pathological manifestations in nine families with 50 affected members.

Fifty individuals in nine families had von Hippel-Lindau disease. Nearly all of the morbidity and mortality of the entity is associated with six of its manifestations, each of which can be successfully treated. Retinal angiomatosis, which occurs in more than half of those affected, can produce blindness if not treated. Cerebellar hemangioblastoma, which is observed in one third of patients, is the most common source of initial symptoms and caused more than half of the deaths in the series. Medullary and spinal hemangioblastomas occur infrequently. Pheochromocytoma is common in certain families and is usually bilateral. Renal cell carcinoma, which generally arises at a later age, may befall the patient who is successfully treated for the tumors that occurred earlier. However, this tumor can be treated also, if there is early detection.

Adenocarcinoma↗
PubMed1976

Dissociation of epithelial cells from rabbit trachea and small intestine with demonstration of APUD endocrine cells.

In this study the entire epithelial lining of tracheas and a 15-cm segments of small intestine were dissociated into individual cell components after 45-minute incubation with 1% pronase. Light and electron microscopy of isolated cells confirmed good morphologic preservation of various epithelial cell types dissociated from the trachea and small intestinal mucosa. Of particular interest was the recovery and preservation of APUD endocrine cells, which are known to be widely dispersed amongst various non-endocrine epithelial cells in both the trachea and small intestine. The APUD cells were demonstrated in dissociated cell preparations by a formaldehyde-induced fluorescence method, Grimelius' silver nitrate stain, and electron microscopy. The isolated APUD cells retained their characteristic features, e.g., amine-handling properties, argyrophilia and cytoplasmic dense-core vesicles. The cell dissociation method described in this report provides high yields of viable epithelial cells in single cell suspensions which are suitable for further cell separation into homogeneous populations of single kinds of cells, including the APUD endocrine cells. Availability of methods for isolation of tracheal and intestinal APUD cells will facilitate further studies, in vitro, on secretory, metabolic and functional aspects of these cells.

Amines↗
PubMed1975

Ultrastructure and fluorescence histochemistry of endocrine (APUD-type) cells in tracheal mucosa of human and various animal species.

This study describes distrinctive cells with ultrastructural and histochemical features of APUD-type endocrine cells within the tracheal epithelium of human fetuses, newborns and children as well as different animal species. These cells referred to as Kultschitzky cells (K cells) were found to be argyrophilic, but not argentaffin, and are considered analogous to the same type of cells in lung and gastro-intestinal tract. Fluorescence histochemistry demonstrated the presence of intracellular amine within tracheal K cells, but only after in-vitro or in-vivo administration of amine precursor (L-DOPA). Ultrastructurally, these cells are characterized by the presence of numerous cytoplasmic granules (dense core vesicles) which show species related morphologic variations. Two different types of K cells were found in trachea of lamb and armadillo, each type possessing morphologically different dense core vesicles. In human and rabbit tracheas, only one type of K cell was identified. K cells in the trachea are distributed as single cells between other epithelial cells; neuroepithelial bodies such as those found in bronchial mucosa were not identified. Well differentiated K cells were found in tracheas of early human fetuses and throughout gestation, infancy, and childhood. Preservation of K cells in human autopsy material and widespread occurence of these cells in various laboratory animals will permit further studies into the nature and function of tracheobronchial endocrine cells.

Animals↗