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Biomedical subjects

M K Chan

Publications and source records attributed to M K Chan.

At least 109 records · Page 6Linked to original sources
PubMed1987

Controlled trial of antiplatelet agents in mesangial IgA glomerulonephritis.

A trial of antiplatelet therapy (slow-release aspirin and dipyridamole) in mesangial IgA glomerulonephritis was conducted. Vitamin B was given to the control group. Altogether, 38 patients were observed for a mean of 33.2 months. Antiplatelet therapy did not favorably modify the course of mesangial IgA glomerulonephritis. The rate of progression of the disease, measured by the slope of reciprocals of serum creatinine v time plots, correlated significantly with the severity of tissue damage as assessed by an arbitrary morphologic score from renal biopsy specimens.

Adult↗
PubMed1987

The influence of permethrin-impregnated bednets and mass drug administration on the incidence of Plasmodium falciparum malaria in children in Sabah, Malaysia.

A small-scale trial was carried out in the Upper Kinabatangan district of Sabah, Malaysia, to determine the effect of using permethrin-impregnated bednets on malaria transmission. A total of 306 nylon bednets with cotton borders, impregnated at a dose estimated to have been 0.062 g permethrin/m2 of nylon netting, were distributed to 139 households in five villages. At the time of distributing bednets, mass drug administration with Fansidar plus primaquine was also administered to the human population to clear all parasitaemias due to Plasmodium falciparum Welch. In another village, for comparison, mass drug administration was the only intervention. After intervention measures in December 1984 and January 1985, the parasite rates in children declined in all villages during the first month, significantly more in the villages with impregnated bednets than in the control, thus proving that the nets had an impact on malaria. However, after about 2 months, parasite rates started to increase again. After 4-6 months, parasite rates in the villages with bednets approached the rate in the control village without nets. The increase in parasite rates was paralleled by a significant deterioration in the quality, physical condition and the degree of non-utilization of bednets. Entomological evaluation proved the efficacy of permethrin-impregnated nets for controlling Anopheles balabacensis Baisas and other anophelines. Bioassays (1 h exposure) of permethrin-impregnated bednets gave 100% mortality initially and 44-61% mortality after 85-106 days. Mosquito collections in treated bednets were significantly reduced for at least 217 days. The project failed to achieve prolonged suppression of malaria transmission for a combination of entomological, sociological and practical reasons which are discussed in relation to the objectives and implementation of future bednet studies.

Animals↗
PubMed1987

Cyclosporin A in steroid-sensitive nephrotic syndrome with frequent relapses.

Eight patients with steroid-sensitive nephrotic syndrome which frequently relapsed despite cyclophosphamide treatment were given cyclosporin A (7.5 mg/kg/day to 10 mg/kg/day) for 8 to 12 weeks. Six had minimal change glomerulonephritis and two had focal segmental glomerulonephritis. Cyclosporin A was given to 5 patients when their nephrotic syndrome was in relapse and to 3 patients when the nephrotic syndrome was in remission. Cyclosporin A induced a transient remission in only one patient.

Adult↗
PubMed1987

Immunoglobulins (IgG, IgA, IgM, IgE) and complement components (C3, C4) in nephrotic syndrome due to minimal change and other forms of glomerulonephritis, a clue for steroid therapy?

Serum IgG, IgA, IgM, IgE, C3 and C4 were measured in 13 patients with minimal change (MC) glomerulonephritis and 10 with the nephrotic syndrome (NS) due to other forms of glomerulonephritis. The tests were repeated in all patients with MC glomerulonephritis when they went into remission. Serum IgG was reduced, IgM, IgE and C3 were raised while serum IgA was within the normal range when the patients were nephrotic. Changes in serum immunoglobulins and complement components were not specific to MC glomerulonephritis and these parameters reverted towards normal when the NS went into remission. Elevated C3 levels probably reflected increased hepatic protein synthesis since C3 correlated significantly with serum cholesterol. There was a tendency for serum IgE concentrations to positively correlate with the total dose of prednisolone required to bring the NS to remission.

Adolescent↗
PubMed1987

Nephrotic syndrome associated with angiofollicular lymph node hyperplasia.

A women presented at the age of 22 with anemia, hepatosplenomegaly, polyclonal hypergammaglobulinemia and a mediastinal shadow. At thoracotomy she had enlarged mediastinal lymph nodes which displayed histological features typical of angiofollicular hyperplasia. Marrow plasmacytosis was present. She developed diabetes mellitus at the age of 29 yrs after she had received oral steroid treatment for one year. The nephrotic syndrome supervened another year later. Her kidneys were enlarged before the onset of diabetes. The glomerular changes included a marked increase of mesangial matrix and segmental hypercellularity. The association of the nephrotic syndrome and angiofollicular lymph node hyperplasia is extremely rare and their interrelation remains enigmatic.

Adult↗
PubMed1987

Adult Fanconi syndrome in kappa light chain myeloma.

Distinctive morphological features in both the marrow infiltrate and the kidney were seen in a 52-year-old woman with kappa light chain-producing plasma cell myeloma, diagnosed on the basis of multiple osteolytic lesions, the presence of atypical plasma cells in the bone marrow, and monoclonal immunoglobulin production as demonstrated by immunoperoxidase staining on marrow sections. Large focal collections of histiocytes in the bone marrow and the renal proximal tubular epithelium had abundant glassy cytoplasm. Characteristic crystalline inclusions were seen ultrastructurally in both types of cells. It is believed that these crystalline deposits are lysosomal inclusions composed of altered kappa light chains taken up by these cells. The renal changes were entirely different from those of myeloma kidneys and were associated with proximal tubular dysfunction of adult Fanconi syndrome without distal tubule abnormality.

Biopsy↗
PubMed1987

Continuous ambulatory peritoneal dialysis (CAPD): experience with the first 100 patients in a Hong Kong centre.

We treated 100 Chinese patients age 16 to 83 years by CAPD, using three 2-litre exchanges per day. The treatment was self-financed in 69 patients, by charitable organisations in 25 patients, and by government funds in 6 patients. Satisfactory biochemistry was maintained and there was no gross hyperlipidaemia, renal osteodystrophy, or loss of ultrafiltration capacity of the peritoneum. Rehabilitation was good and 62% of patients returned to full-time employment. The average duration of hospitalization was 11.3 days per patient year. Peritonitis usually due to Staphylococcus pyogenes occurred at a frequency of one episode per 12.3 patient-months. Sixteen patients were transplanted and had a 2-year graft survival of 78.5%. The cumulative patient survival was 97% at 1 year and 84% at 2 years. The corresponding technique survival rates were 87% and 76% respectively.

Adolescent↗
PubMed1987

Ofloxacin pharmacokinetics in patients on continuous ambulatory peritoneal dialysis.

Pharmacokinetics of ofloxacin (OFX) was studied in patients on continuous ambulatory peritoneal dialysis (CAPD) carrying out three exchanges per day. In 11 patients given 300 mg of OFX orally, serum OFX concentration peaked at 2.44 mg/l 3.7 hours after administration and the mean elimination half-life of OFX was 25 hours. OFX concentrations in peritoneal fluid underwent cyclical changes with each change of solutions, reaching beyond 0.5 mg/l after 2 hours of equilibration. There was a highly significant correlation between corresponding serum and peritoneal fluid concentrations of OFX after an 8 h equilibration (r = 0.85, p less than 0.001). In 5 patients given a 400 mg loading dose followed by 200 mg of OFX per day for 7 days, trough serum OFX concentrations ranged from 1.35 to 7.00 mg/l and no adverse effects were noticed. CAPD per exchange removed less than 2% of the total dose of OFX given.

Adult↗
PubMed1987

Acute inflammation in gram-negative infection: endotoxin, interleukin 1, tumor necrosis factor, and neutrophils.

Experimental bacterial infection of the dermis induced with gram-negative microorganisms is associated with an acute inflammatory reaction, which represents the principal local defense against spread of the infection. When the inflammatory reaction is quantitated with radiolabeled cells and proteins, the kinetics resemble acute inflammation induced with other agents, such as immune complexes or chemotaxins. There is an interrelationship between the components or events of the inflammatory reaction; inasmuch as vascular injury is neutrophil-dependent, neutrophils must migrate to the site where the bacteria multiply. In neutropenic animals there is no such emigration and bacterial multiplication is not inhibited. The microorganisms shed endotoxin, which in turn induces secretion of interleukin 1 (IL 1) and probably tumor necrosis factor. Endotoxin is the most potent agent (10(-15) mol vs. 10(-12) mol of C5ades Arg) capable of inducing a neutrophil influx. Desensitization or tachyphylaxis of the tissues (probably of postcapillary venular endothelium) to IL 1 seems to control cessation of the neutrophil influx (also in vitro evidence). Phagocytosis of the bacteria by neutrophils is associated with release of oxygen radicals and lysosomal proteases from the neutrophils. These are instrumental in eliciting microvascular injury, which is characterized by enhanced vasopermeability, hemorrhage, and thrombosis.

Acute Disease↗
PubMed1986

Modulation of phospholipid methylation in rabbit leukocytes by indomethacin.

Methylation of membrane phospholipids has been implicated as an early biochemical signal for the chemotactic migration of phagocytic cells into inflammatory sites. In this study, the ability of indomethacin to modulate phospholipid methylation as one of its mechanisms of antiinflammatory action was investigated. Nontoxic doses of indomethacin (10(-4) M and 10(-5) M) were found to retard the methylation of phosphatidylmonomethylethanolamine (PMME) to phosphatidyldimethylethanolamine (PDME) and phosphatidylcholine (PC) in rabbit leukocytes, suggesting inhibition of methyltransferase II activity. Indomethacin was, however, without effect on the uptake of L-[methyl 3H]methionine by rabbit leukocytes. It is suggested that the inhibition of membrane phospholipid methylation could result in the suppression of inflammatory responses such as prostaglandin and leukotriene synthesis, generation of reactive oxygen radicals, and chemotaxis.

Animals↗
PubMed1986

Oliva vidua fulminans, a marine mollusc, responsible for five fatal cases of neurotoxic food poisoning in Sabah, Malaysia.

This is the first report in which a marine mollusc, Oliva vidua fulminans (olives), generally not known to be poisonous, was responsible for death in five children after consuming boiled olives with tamarind. The onset of symptoms was rapid 10 to 20 min after consumption of the olives. Signs and symptoms included nausea, vomiting, abdominal pain, tingling sensation around the lips, numbness around the mouth, drowsiness, lethargy and generalized weakness with paraesthesia in the limbs. The five deaths occurred within 3 to 4 hours after eating the poisoned olives and resulted from respiratory failure. Left-over olives from the affected household and freshly collected live olives had a toxicity of 14,200 mouse units (M.U.) and 15,000 M.U. per 100 g meat respectively. No other common chemical poison and organophosphorus insecticides were detected. The neurotoxic agent was acid and heat stable and was toxic at pH less than 4. Its action was similar to that of paralytic shellfish poisoning which was caused by toxins from certain dinoflagellates.

Adolescent↗