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Biomedical subjects

S Y Wong

Publications and source records attributed to S Y Wong.

At least 19 recordsLinked to original sources
PubMed1992

Synthesis of 1-N-glycyl beta-oligosaccharide derivatives. Reactivity of Lens culinaris lectin with a fluorescent labeled streptavidin pseudoglycoprotein and immobilized neoglycolipid.

The lectin from Lens culinaris (lentil) has a binding specificity for glycopeptides bearing 6-O-linked fucose on the reducing terminus on complex-type N-linked oligosaccharides. Lentil lectin therefore provides an excellent example of a carbohydrate binding protein in which high-affinity interactions are dependent on the integrity of the oligosaccharide core structure. We report here the synthesis of the 1-N-glycyl beta-derivative of Gal beta 4GlcNAc beta 2Man alpha 6(Gal beta 4GlcNAc beta 2Man alpha 3)Man beta 4GlcNAc beta 4(Fuc alpha 6)-GlcNAc (Gal-2F) and its subsequent biotinylation and palmitoylation. The biotin derivative when bound to a streptavidin-fluorescein isothiocyanate (FITC) conjugate was able to bind to both concanavalin A (ConA) and lentil lectin affinity columns. In contrast, synthesis of the biotin derivative of the glycamine derivative of Gal-2F and subsequent binding to streptavidin-FITC afforded reactivity to a ConA affinity column but not to a lentil lectin affinity column. Lentil lectin also bound to plastic microtiter plates containing the adsorbed palmitoyl-1-N-glycyl beta-derivative. No binding occurred when the homologous glycamine neoglycolipid was used. These results suggest the 1-N-glycyl beta-derivative of oligosaccharides may have general utility as an intermediate in the synthesis of novel glycoconjugate probes.

Bacterial Proteins↗
PubMed1992

Transmission of disseminated histoplasmosis via cadaveric renal transplantation: case report.

A 30-year-old woman received a cadaveric renal allograft from a donor who was subsequently found to have renal infection due to Histoplasma capsulatum. The recipient had funguria in the early postoperative period and later developed cutaneous manifestations of disseminated histoplasmosis. We report a case of histoplasmosis transmitted via renal transplantation and describe the subsequent 20-year clinical course.

Adult↗
PubMed1992

Thrombospondin and other possible related matrix proteins in malignant and benign breast disease. An immunohistochemical study.

Thrombospondin (TSP), which plays an important hemostatic role, is a 450-kd cytoadhesive protein present in the alpha granules of platelets. In vitro experiments using cultured malignant cells suggest that it may help to mediate malignant cell attachment to extracellular matrix and may be important in cancer invasiveness. The authors studied a group of malignant and benign breast tissues for the expression of TSP and provide evidence that TSP may have a role in tumor invasiveness. Using immunohistochemical techniques, the authors found in 48 fresh specimens of breast carcinoma that TSP stained strongly in the desmoplastic stroma or at the basement membrane associated with the malignant ductal epithelium. Tumor cells abutting these tissues revealed cytoplasmic staining for TSP. Stronger TSP staining was seen in the poorly differentiated tumors. These findings were compared with those of normal and benign breast tissue, which showed no TSP staining apart from reactivity in the large distended cysts of fibrocystic disease and faint staining in the stroma of fibroadenomas. Staining for integrin was positive in lymphocytes of both malignant and benign breast disease and equivocally also in the stromal cells of the breast cancer tissue. Immunoreactivity to TSP in tissues was also compared with that of fibronectin, laminin, and collagen type I, III, and IV. The overall findings suggest that thrombospondin may have a role in the tumor biology of invasiveness.

Adult↗
PubMed1992

Metabolic studies in kidney stone disease.

Patients with kidney stones (n = 59) and healthy controls (n = 31) collected a 24-hour urine sample and later underwent a 6-hour 'fast and load' test in which an oral calcium load was taken after 2 hours. In the 24-hour urine sample, mean calcium excretion was higher in patients than controls, while mean urate, oxalate and citrate levels were similar. The patients had higher levels of fasting plasma calcium, serum calcitriol and fasting urinary calcium, and lower levels of plasma phosphate than did the controls. Following the calcium load, plasma and urinary calcium increased similarly in both groups. Serum parathyroid hormone (PTH) levels were similar in both groups and decreased similarly following the calcium load. Multiple linear regression, relating the presence or absence of stone formation to all variables, found the only variables significantly related to stone formation to be plasma levels of calcium (p less than 0.001) and phosphate (p = 0.001) and fasting urinary urea (p less than 0.001), and 24-hour urinary calcium excretion (p less than 0.05). Urinary oxalate and citrate were not related to stone formation. The data do not support the hypothesis that primary stimulation by calcitriol produces a normal fasting plasma calcium level, with an exaggerated increase after an oral calcium load. The findings instead suggest an abnormality of parathyroid cell 'set point', such that PTH secretion continues until the plasma calcium level is a little higher and the phosphate a little lower than in controls.

Adult↗
PubMed1991

Malignant glandular triton tumor.

A case of left brachial plexus-related malignant peripheral nerve sheath tumor showing neoplastic, glandular, and rhabdomyoblastic elements in a 39-year-old Chinese man is reported. The authors suggested that this tumor be termed a malignant glandular triton tumor in view of the presence of the adenocarcinomatous component. The patient had extensive local recurrence comprising mainly the Schwann spindle cells within a year after complete piecemeal removal and died 15 months later after the initial presentation. The natural behavior of this tumor, as in other reported cases of malignant triton tumor, is extremely aggressive, unlike malignant schwannoma or glandular malignant schwannoma. The histogenesis of this tumor is likely to be from primitive neural crest cells, Schwann's cell precursors, or metaplastic malignant Schwann's cells.

Adult↗
PubMed1991

An outbreak of aflatoxicosis and boric acid poisoning in Malaysia: a clinicopathological study.

An outbreak of food poisoning resulting in 13 deaths in children occurred in Malaysia during the Chinese Festival of the Nine-Emperor Gods in 1988. The offending food was a Chinese noodle called 'Loh See Fun' (LSF). The source was traced to a factory where a banned food preservative was added to make the LSF. The food poisoning was attributable to aflatoxins and boric acid. The clinical features included vomiting, pyrexia, diarrhoea, abdominal pain, anorexia, giddiness, seizures, and eventual coma. Initially, many presented with a Reye-like syndrome. Eleven post-mortem examinations were performed. The pathological findings included extensive coagulative necrosis of the liver with proliferative 'ductal/ductular metaplasia of the hepatocytes'. Giant cell formation, central vein sclerosis, bile stasis, and steatosis were also noted. There was presence of acute tubular necrosis, superficial upper gastrointestinal erosions, and ensuing encephalopathy. The eventual cause of death is acute hepatic and renal failure.

Aflatoxins↗
PubMed1991

Epstein-Barr virus--a possible missing link in the initiation of cervical carcinogenesis?

Salient epidemiological and molecular biological features of Epstein-Barr virus (EBV) infection correlate well with the natural history of carcinoma of the cervix. It is therefore hypothesised that the incorporation of EBV into the genome of cervical epithelial cells at an early age (teens) could be an important early event in cervical carcinogenesis.

Female↗
PubMed1991

HTLV-1 associated T cell lymphoma in South East Asia: case report and family study.

Geographic clustering of human T cell lymphoma/leukaemia virus type 1 (HTLV-1) infection is well recognised, particularly in south western Japan, parts of West and Central Africa, the south eastern United States and the Caribbean islands. Sporadic cases have been reported in many other parts of the world. The first case of HTLV-1 associated leukaemia/lymphoma (ATLL) in South East Asia is reported. Contact tracing showed a high incidence of carriers among the relatives.

Carrier State↗
PubMed1991

Immunohistochemical assessment of ER-P31, a mouse anti-oestrogen receptor protein monoclonal antibody in human breast cancers: comparison with ER-ICA (Abbott) and radioligand assays.

A new mouse anti-oestrogen receptor (ER) monoclonal antibody, ER-P31, has been developed. Comparisons of immunohistochemical detection of ER in human breast cancers using ER-P31 with anti-ER from ER-immunocytochemical assay (ER-ICA; Abbott Diagnostic Division) and radioligand dextran-coated charcoal (DCC) assays were carried out. A total of 63 breast cancers, both ER-negative and -positive, were tested. A highly significant degree of correlation between immunostaining for ER-P31 and both ER-ICA and DCC assays was obtained. It is hoped that once ER-P31 is widely available commercially, determination of ER status in breast cancers should be routinely and economically available to all women with breast cancer. Moreover, with the introduction and implementation of a screening programme for detecting breast cancers, immunocytochemical determination of ER status in unequivocal and equivocal positive fine-needle aspirates of breast lesions can be readily performed.

Alkaline Phosphatase↗
PubMed1990

Bone death in hip fracture in the elderly.

We examined femoral head bone from 50 cadavers and from 21 patients who had suffered pathologic fracture of the femoral neck. We used a histochemical technique for lactate dehydrogenase (LDH) activity to demonstrate osteocyte viability. The femoral heads were removed within 36 hours of death or fracture, as LDH activity persists in the cytoplasm of viable cells for this time at 37 degrees after interruption of the blood supply. In the controls, there was an age-related reduction in mean osteocyte viability, from 88 +/- 7% (mean +/- SD) at age 10-29 years to 58 +/- 12% at age 70-89 years. In the hip fracture patients, mean osteocyte viability was 58 +/- 21% but there was much variability in both osteocyte viability and bone mass. In 5 fracture patients, there was extensive osteocyte death, suggesting that most of the femoral head bone was nonviable; these patients had little microfracture callus. Others had predominantly viable bone which was usually osteoporotic, and their bone frequently showed microfracture callus. Osteomalacia was not seen in any patient. It is suggested that bone death, in addition to osteoporosis, may sometimes contribute to hip fracture in the elderly.

Aged↗
PubMed1990

Breast cancers with extremely high oestrogen receptor protein status.

Seventeen cases of primary and one case of metastatic breast cancer which expressed greater than 900 fmol oestrogen receptor sites per mg soluble protein were examined. All these patients were post-menopausal at the time of their presentation. These were a heterogeneous group of well-differentiated cellular breast carcinomas, comprising cases of invasive duct carcinoma with extensive tubular differentiation or with focal argyrophilia, tubulolobular carcinoma, lobular carcinoma of mixed type containing abundant intracytoplasmic lumina, papillary carcinoma and type B colloid carcinoma. There was very little tumour necrosis. Nodal metastasis, tumour size and host inflammatory response did not appear to show any relationship with oestrogen receptor status. The patients, apart from two who died from other causes, remain alive (Fisher's exact test, P less than 0.01). In contrast, 17 randomly selected cases of oestrogen receptor negative breast cancer in the same study period were focally necrotic, poorly-differentiated invasive duct carcinomas. Six patients died from metastatic disease, seven were alive and well, one was alive with metastatic disease, one was lost to follow-up and two died from diseases unrelated to breast cancer.

Age Factors↗
PubMed1989

Measurement of bone in the os calcis: a clinical evaluation.

Bone mineral content (BMC) was measured in the os calcis of 232 normal subjects aged 17-82 years. The mean reproducibility (coefficient of variation) of the measurement was 1.8%. Substantial bone loss occurred between the ages of 20 and 50 years, and in females the menopause was associated with additional bone loss. There was no significant difference in the rate of bone loss in females and males, but the mean BMC was greater at all ages in males than in females. We also compared os calcis BMC with spinal bone mineral density (BMD), measured by quantitative computed tomographic (CT) scanning, in 85 subjects: 33 were normal controls, 19 had osteoporosis defined by the presence of one or more pathological fractures, and in the remainder the CT examination was performed at the patient's request. Os calcis BMC correlated with spinal BMD in both females (r = 0.69, p less than 0.001) and males (r = 0.84, p less than 0.001). However, the os calcis BMC did not reliably predict spine values around the CT "fracture threshold" of 90-100 mg/cm3 and did not correlate with osteoporotic fracture as well as did spinal BMD. It is concluded that measurement of the os calcis BMC is of limited clinical usefulness for the early diagnosis of osteoporosis.

Adolescent↗
PubMed1989

JC virus genomes in progressive multifocal leukoencephalopathy: detection using a sensitive non-radioisotopic in situ hybridization method.

JC virus genomes have been localized in formalin-fixed, paraffin-embedded brain tissues of two cases of known progressive multifocal leukoencephalopathy by in situ hybridization utilizing a biotinylated JC virus DNA probe. A three-stage immunoperoxidase system with gold-silver amplification of the diaminobenzidine substrate was used to visualize biotinylated nucleic acid hybrids. Dot-blot quantification of this visualization system indicates that subpicogramme amounts of biotinylated DNA can be detected. Optimal detection of the virus genomes in the brain tissues required a microwave irradiation step prior to hybridization. JC virus genomes were observed in the nuclei of enlarged oligodendrocytes and of some bizarre astrocytes. No other cell types were found to harbour the genomes.

Brain↗
PubMed1989

Bilateral massive ovarian oedema--report of a case due to lymphangiitis carcinomatosa.

A 40 year-old Caucasian woman, with clinical and radiological evidence of pulmonary lymphangiitis carcinomatosa presented with weight loss, productive cough and lower abdominal pain. At operation, she was found to have massive bilateral ovarian oedema. No abdominal primary tumour was found. A transbronchial biopsy showed extensive infiltration by a poorly differentiated, focally necrotic cribriform adenocarcinoma and there was extensive lymphatic permeation by this metastatic carcinoma in the stroma of the cervix uteri, myometrium, mesosalpinx, mesoovarii, surface of the ovaries, rectosigmoid colonic wall and peritoneal fat. The cut surface of the enlarged, soft and fluctuant ovaries oozed oedema fluid readily. Histologically, there was wide separation of the stromal cells by oedema in the ovaries which contained many dilated lymphatics. Compression and collagenization of the outer cortex was noted. The pathogenesis of the massive ovarian oedema was apparently due to neoplastic obstruction of the lymphatic system.

Adenocarcinoma↗