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Biomedical subjects

H K Ngai

Publications and source records attributed to H K Ngai.

12 recordsLinked to original sources
PubMed2003

A ubiquitin-like peptide with ribonuclease activity against various polyhomoribonucleotides from the yellow mushroom Cantharellus cibarius.

A peptide, with a molecular weight of 9K and an N-terminal sequence identical to that of ubiquitin, was isolated from fresh fruiting bodies of the yellow mushroom Cantharellus cibarius. The peptide manifested ribonucleolytic activity toward poly A, poly C, poly G, and poly U, with the activity toward the first two polyhomoribonucleotides being higher. Maximal activity toward yeast tRNA was observed at a temperature of 70 degrees C and a pH of 7. The peptide was adsorbed on DEAE-cellulose, CM-Sepharose, and Q-Sepharose. The yield of the peptide was 7mg from 1.8kg mushroom.

Amino Acids↗
PubMed1985

A rapid method for reprocessing paraffin sections for diagnostic electron microscopy.

A rapid method for re-embedding paraffin sections into epoxy resin for diagnostic electron microscopy is described. The method requires a relatively shorter time than the traditional block retrieval technique and produces a reasonable retrieval technique and produces a reasonable quality of ultrastructure for diagnostic purposes.

Carcinoma, Squamous Cell↗
PubMed1984

Resin-slide for X-ray analysis of inorganic deposits on paraffin sections in the scanning electron microscope.

A preparation method for x-ray analysis of inorganic deposits on paraffin sections is described. It involves the use of resin-slides for mounting paraffin sections which are then dewaxed, carboncoated and examined in the SEM. The resin support, being much cheaper than the carbon planchet and having a perfectly flat surface, facilitates the adhesion of paraffin sections to it, and slides can be stored desiccated for retrospective study. The method also permits direct examination of sections under a light microscope to locate areas of interest. It is simple and useful for the analysis of inorganic inclusions in biological samples.

Elements↗
PubMed1982

The preparation of glomeruli from renal biopsy specimens for scanning electron microscopy.

A method for the preparation of human renal biopsy specimens for scanning electron microscopy (SEM) is described. This involves glomerular isolation by fine needle dissection and the simultaneous processing of 10 or more specimens in a specially designed tissue cassette. The method is simple and reliable with minimal glomerular loss during processing. Processed glomeruli appear intact under the SEM. They have clean surfaces with minimal extraneous deposits. Surface topography of the glomerulus is clearly seen and changes of the podocytes in glomerular diseases can be readily studied.

Biopsy↗
PubMed1980

Effects of 6-chloro-6-deoxyglucose on electrolyte and water transport in the epididymis and fertility of male rats.

The effects of 6-chloro-6-deoxyglucose (6 CDG) on the transport of electrolytes and water in the cauda epididymidis and fertility of male rats were studied. Injection of 6 CDG into male rats at a dose rate of 120 muM/kg/day for 7-14 days induced sterility and inhibited sodium and water reabsorption in the perfused cauda epididymidis by about 60%. The rates of potassium and protein secretion were unaffected. When these rats were allowed to recover for 10 weeks, both fertility and the Na and water reabsorption of the cauda were restored. It is proposed that the chlorinated sugar may affect epididymal sperm metabolism through an effect on the transport function of the epididymis.

Animals↗
PubMed1980

The isolated duct of the rat cauda epididymidis as a model for isosmotic transport studies.

Electrolytes and water transport have been studied in the perfused isolated duct of the rat cauda epididymis in vitro. The rates of reabsorption of sodium, chloride and water and of secretion of potassium were found to be comparable to those in the perfused rat cauda epididymidis in vivo. Sodium reabsorption was isotonic and inhibited by the metabolic uncoupler 2,4-dinitrophenol and cooling. Removal of sodium ions from the intraluminal fluid abolished water reabsorption in the isolated duct. When potassium ions were removed from the peritubular medium the secretion of potassium was abolished, but the reabsorption of sodium and water was unaffected. Under this condition, the reabsorption of chloride was enhanced. Removal of calcium ions from the lumen increased the rates of sodium and water reabsorption and potassium secretion by twofold. Amiloride (10(-4) M) added to the intraluminal fluid had no effect on the electrolyte and water transport in the isolated duct, whereas triaminopyrimidine produced a dose-dependent inhibition of sodium and water reabsorption when added to both sides. Sodium and water reabsorption were found to be inhibited by the application of ouabain (10(-3) M) to the peritubular side and of ethacrynic acid (10(-4) to 10(-5) M) to the luminal peritubular side and of ethacrynic acid (10(-4) to 10(-5) M) to the luminal side. These results are discussed in the light of the recent concepts of isosmotic transepithelial transport.

Amiloride↗