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K M Chan

Publications and source records attributed to K M Chan.

At least 235 records · Page 13Linked to original sources
PubMed1987

Male-enhanced expression and genetic conservation of a gene isolated with an anti-H-Y antibody.

The hypothesis of the serological H-Y antigen as the inducer molecule for mammalian male sex differentiation has been considered an important working model in developmental biology. However, because of the difficulties involved in its detection, supporting evidence in molecular terms is lacking for this hypothesis. The isolation of the gene for the serological H-Y antigen is essential to the acertainment of its proposed functions. Using recombinant DNA technology and specific anti-H-Y sera we have isolated a candidate gene, the MEA gene, for the serological H-Y antigen. Molecular characterization of the MEA gene shows male-enhanced expression and genetic conservation patterns similar to those attributed to the serological H-Y antigen. The isolation of this candidate gene for the serological H-Y antigen. The isolation of this candidate gene for the serological H-Y antigen would allow further investigations to identify the functions for this molecule in molecular terms.

Aging↗
PubMed1987

Interference of the chemotherapeutic agent etoposide with the direct phosphotungstic acid method for uric acid.

A 62-year-old woman receiving chemotherapy with etoposide showed discrepant uric acid values as measured by a direct phosphotungstic acid (PTA) method (150 mg/L) compared with a uricase technique (40 mg/L). After ultrafiltration, the positive interference for the direct PTA method was retained in the protein fraction, but not in the filtrate. Adding exogenous etoposide to drug-free serum confirmed this interference for the direct PTA method, but not for the uricase procedure or a PTA technique preceded by dialysis. Decisions for aggressive patient management are often based on the magnitude of hyperuricemia. We do not recommend that the direct phosphotungstic acid method be used to measure uric acid in patients receiving etoposide.

Etoposide↗
PubMed1987

The theophylline method of the Abbott "Vision" analyzer evaluated.

We evaluated the analytical performance of the Abbott "Vision" analyzer for theophylline measurement. The within-day precision (CV) was 1.8% and 3.1% at theophylline concentrations of 15.2 and 25.2 mg/L, respectively; between-day precision was 3.5% and 4.8% at 14.9 and 24.4 mg/L, respectively. Bilirubin (143 mg/L) and triglyceride (7.4 g/L) did not interfere, but hemoglobin caused lower values for apparent theophylline, the magnitude of the decrease being proportional to the hemoglobin concentration. At the cutoff concentration of 1 g/L programmed into the instrument by the manufacturer, hemoglobin reduced the theophylline value by less than 10%. Results by the Vision method (y) compared well with those by the "TDX" procedure (x): r = 0.98, y = 0.978x - 0.270 mg/L. The Vision method gave comparable theophylline values for serum, plasma, and whole-blood samples. We also validated analytically and clinically that capillary blood samples collected by finger stick can be used interchangeably with blood samples collected by venipuncture for monitoring theophylline therapy.

Autoanalysis↗
PubMed1986

A direct colorimetric assay for Ca2+ -stimulated ATPase activity.

A simple and rapid colorimetric assay for measuring the high affinity Ca2+-ATPase activity in subcellular fractions is presented. With this method a one-step addition of a malachite green/molybdate/polyvinyl alcohol reagent to the assay mixture at the end of the incubation period is all that is required for the spectrophotometric quantification of the phosphomolybdate-malachite green complex. The presence of polyvinyl alcohol allows the quantification of released phosphate without having to separate it from protein. We have validated this assay by characterizing the high affinity Ca2+-ATPase activity in isolated rat liver microsomes. Comparable Ca2+-ATPase activities in rat liver microsomes and adipocyte plasma membranes were found when measured with this colorimetric assay and an isotopic assay. This method is applicable to the measurement of other types of ATPase activities.

Adipose Tissue↗
PubMed1985

The mechanism of calcium uptake by liver microsomes: effect of anions and ionophores.

The mechanism of calcium uptake by liver microsomes was investigated using various anions and ionophores. Calcium uptake was shown to be specific to microsomes and unlikely to be due to contamination by plasma membranes by correlation of calcium uptake to the marker enzymes specific for these two fractions. Under the conditions employed, phosphates, sulfate, chloride, acetate, nitrate, thiocyanate, maleate, succinate and oxalate all stimulated calcium uptake by microsomes, but to different degrees. The greatest effect (4-6-fold) was observed with phosphate. On the contrary, phosphate is the only anion that stimulates the plasma membrane calcium uptake to any significant degree. Treatment of isolated microsomes with 4,4'-diisothiocyano-2,2'-disulfonic acid stilbene (DIDS) resulted in inhibition of ATP- and anion-dependent calcium uptake. A lipid-permeable organic acid such as maleate retained its ability to promote calcium uptake in DIDS-treated microsomes. However, a lipophilic anion, such as nitrate, stimulated calcium uptake only in the presence of the protonophore carbonyl cyanide m-chlorophenylhydrazone (CCCP). In addition, 2 microM valinomycin, when added in the absence or presence of 10 to 100 mM K+, had no stimulatory effect on calcium uptake. These results appear to be consistent with a model in which the active uptake of calcium into microsomes involves electroneutral Ca2+-nH+ exchange.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1985

Fractured patella: operative treatment using the tension band principle.

The tension band principle was applied in the operative treatment of fractures of the patella in 139 patients, of which 100 were reviewed retrospectively; 61 per cent were males and 70 per cent were aged between 50 and 70. The fractures were treated soon after admission and movement of the knee was started as soon as possible after the operation. Sixty-eight patients were reviewed and 72 per cent were happy with the resulting knee function. Objectively, 81.3 per cent had an excellent or good result. Minor troubles from the operations were common but it was concluded that the wiring of fractured patellas using the tension band principle is a safe and effective technique.

Adult↗
PubMed1985

Ankle fracture treated with the AO principle--an experience with 116 cases.

One hundred and sixteen cases of ankle fractures were classified by the AO system and treated by open reduction and internal fixation in accordance with the AO principles. The stabilization of the lateral malleolus was emphasized. Ninety-six cases were available for functional assessment with an average follow-up of 39 months. The results were good or excellent in 90 per cent of type A fractures and in 70-80 per cent of type B and C fractures. There was no death or non-union. Local complications included wound infection (8.6 per cent) and skin necrosis (3 per cent). This study illustrates the importance of exact anatomical reduction and stable internal fixation to allow early movement after an intra-articular fracture of the ankle.

Adult↗
PubMed1985

Conservative treatment of paraplegia following acute trauma in a patient with tuberculous kyphosis: case report and review of the literature.

This is the third known reported case in the medical literature of complete paraplegia following acute trauma in a patient with tuberculous kyphosis. Early clinical evidence of neurological recovery and the absence of a radiological fresh lesion are important indications for conservative treatment. The patient made a complete recovery. The mechanism of injury is probably both mechanical and vascular.

Accidents, Traffic↗
PubMed1985

Effects of dextran on five biuret-based procedures for total protein in serum.

We evaluated the effect of dextran on values for total protein in serum as measured by the biuret method with five widely used automated instruments: the American Monitor Parallel; the Du Pont aca II; the Roche Cobas-Bio; the Kodak Ektachem 400; and the Beckman Astra 8. Dextran concentrations as great as 25 or 30 g/L had relatively little or no influence on total protein measurements by the latter three instruments. Dextran concentrations exceeding 6 g/L caused falsely low results with the aca, whereas the Parallel gave falsely high results when the dextran concentration exceeded 2 g/L. The aca total protein procedure could be protected from the interference by dextran concentrations up to 30 g/L by injecting 0.4-0.8 mL of ethylene glycol directly into the reagent pack before sampling. However, we could not eliminate the interference with the Parallel procedure by any simple means; we thus recommend that it not be used for measuring total protein in serum samples from patients who are being treated with dextran.

Adult↗