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Biomedical subjects

R G Price

Publications and source records attributed to R G Price.

At least 91 records · Page 5Linked to original sources
PubMed1978

N-acetyl-beta-d-glucosaminidase in marmoset kidney, serum and urine.

N-Acetyl-beta-D-glucosaminidase activities were determined in homogenates of marmoset kidney, in serum and in urine by using the 4-methylumbelliferyl substrate. The enzyme activity was separated into several components by DEAE-cellulose ion-exchange chromatography, starch-gel electrophoresis and isoelectric focusing. The kidney contained two major forms of the enzyme, A and B, which had similar pH optima and Km values. The A-form bound to DEAE-cellulose at pH 6.8, migrated towards the anode on starch-gel electrophoresis and had a pI of 5.0. The B-form did not bind to DEAE-cellulose at pH 6.8, remained near the origin on starch-gel electrophoresis and had a pI of 7.64. The isoenzymes also differed in heat stability, the B-form being the more stable. Serum contained B-form activity and, in addition, two intermediate forms (I1 and I2) were loosely bound to DEAE-cellulose. The serum A-form activity was less firmly bound to DEAE-cellulose than was the tissue A-form and was designated As. Serum from a pregnant marmoset contained a form which may be analogous to the human P-isoenzyme. Urine contained only a small amount of B-form activity, the majority being present in the A-form. The kidney A- and B-forms both had mol.wts. of 96000--100000 and the activity was predominantly lysosomal. Partial purification of the kidney A isoenzyme was undertaken. Immunoprecipitation studies indicated a relationship between marmoset kidney A-form and human liver A-form activity.

Acetylglucosaminidase↗
PubMed1977

Studies on the metabolism of the renal glomerular basement membrane. Turnover measurements in the rat with the use of radiolabeled amino acids.

The synthesis and degradation of the renal glomerular basement membrane have been investigated in the rat with the aid of injected tracer doses of various tritiated amino acids including L-proline, L-lysine, L-phenylalanine, L-leucine, and glycine. After incorporation into the basement membrane the turnover times of these amino acid constituents, as well as of hydroxyproline and hydroxylysine, were determined from the decay in their specific radioactivities. The loss of radioactivity from the proline and hydroxyproline of the glomerular basement membrane was as slow as that from tail tendon collagen in the same animals (turnover time of more than 100 days) and contrasted with the radiodecay of the proline in other glomerular proteins (turnover time of 9 days). The glycine of the membrane similarly turned over at this very slow rate. The total replacement times of the leucine, hydroxylysine, lysine, and phenylalanine constituents of the basement membrane were determined to be somewhat shorter with a range of 65 to 23 days. The nonuniform turnover of these membrane components may be a function of the polydispersity of the peptide subunits of the basement membrane observed by polyacrylamide gel electrophoresis and may reflect a subtle morphological and functional heterogeneity. The amino acid and saccharide composition of the rat glomerular basement membrane used in these studies are also reported.

Amino Acids↗
PubMed1977

The separation and characterization of marmoset kidney beta-D-galactosidase and beta-D-glucosidase.

beta-D-Galactosidase and beta-D-glucosidase activities were determined in homogenates of marmoset kidney by using the appropriate 4-methylumbelliferyl glycoside, beta-D-Galactosidase activity was separated into two main components by ion-exchange chromatography on DEAE-cellulose, starch-gel electrophoresis, isoelectric focusing and gel filtration on Sephadex G-200. One form designated A had a pI of 5.1, was loosely bound to DEAE-cellulose at pH7.0, remained near the origin on starch-gel electrophoresis at pH 7.0 and had an apparent molecular weight of 160000. The second beta-D-galactosidase component, designated B, was associated with the total beta-D-glucosidase activity, had a pI of 4.3, was firmly bound to DEAE-cellulose, migrated rapidly towards the anode on starch-gel electrophoresis and had an apparent molecular weight of 50000. The optimum pH values of beta-D-galactosidase A and B were 4.5 and 6.0 respectively. beta-D-Galactosidase A was activated by 0.1 M-NaC1 but the activity of the B form was inhibited by 1 M-NaC1 at pH 4.5. beta-D-galactosidase had a bimodal distribution, the A form being recovered in the lysosomal fraction whereas the B form was present in the soluble fraction, as was the major portion of the beta-D-glucosidase activity. The lysosomal and soluble forms were further characterized by DEAE-cellulose chromatography.

Animals↗
PubMed1977

Changes in rat renal cortex, isolated plasma membranes and urinary enzymes following the injection of mercuric chloride.

Some of the biochemical changes in rat kidney following the administration of mercuric chloride have been determined. Mercuric chloride had an immediate effect on the renal brush border resulting in rapid loss of the microvilli. Plasma membranes were isolated and characterised at various stages in the necrotic process, mircovilli were absent from these preparations and the activities of marker enzymes for the brush border were significantly decreased. In contrast the basal plasma membranes were unaffected by the nephrotoxin during the early stages and no change occurred in the activity of (Na+ + K+)-ATPase, a marker enzyme for the basal membranes. The change in the pattern of urinary enzyme excertion closely paralleled the ultrastructural changes in the tubular cells. The sequence of subcellular change following the administration of mercuric chloride is discussed in relation to the known mechanism of action of this agent.

Acid Phosphatase↗
PubMed1976

A note on the practical aspects of the assay of N-acetyl-beta-glucosaminidase in human urine.

1. Some practical aspects of the assay of urinary N-acetyl-beta-glucosaminidase activity were studied in patients with renal disease. 2. Centrifugation and dialysis of urine were not necessary prior to assay. 3. When enzyme activity was related to urinary creatinine random urine samples could be used. 4. Since preservatives used to prevent bacterial growth may inhibit enzyme activities, samples should be assayed immediately after collection or stored at 4 degrees C or 20 degrees C. 5. Mild visible haemoglobinuria, eg. derived from lysed red blood cells did not interfere with the enzyme assay.

Acetylglucosaminidase↗
PubMed1975

Presence of serum and tissue forms of N-acetyl-beta-glucosaminidase in urine from patients with renal disease.

1. The A, B, I1 and I2 forms of N-acetyl-beta-glucosaminidase present in urine, serum, kidney, liver and cerebral spinal fluid were separated on DEAE-cellulose and their presence confirmed by cellogel electrophoresis. The relative activities of each enzyme were determined by integrating the area under the elution peaks. 2. Serum A-form was eluted at a lower molarity of chloride than liver A-form and this was designated the As-form to distinguish it from the A-form of N-acetyl-beta-glucosaminidase found in liver and kidney. 3. The P-form of N-acetyl-beta-glucosaminidase present in the serum of a group of pregnant women was not detectable in urine samples from the same women. 4. Urinary NAG activities were found to be abnormally high in patients with impaired renal function. 5. The activity of both N-acetyl-beta-glucosaminidases A and B increased in pathological urines. The higher the total N-acetyl-beta-glucosaminidase activity excreted the higher the % of activity of the B-form present. 6. In a number of patients with haematuria an A-form similar to the serum As-form was present in the urine.

Acetylglucosaminidase↗
PubMed1975

Urinary N-acetyl- beta-D-glucosaminidase activities in patients with renal disease.

Urinary N-acetyl-beta-D-glucosaminidase (NAG) activities were assayed in every urine void throughout 24 hours in 17 normal people and in four patients with renal disease. The variation in NAG activity due to changing rates of urine flow was almost eliminated by factoring enzyme activity by the urinary creatinine concentration. Random samples of urine may thus be used for assay. The results of NAG assay in 36 patients with acute and chronic renal diseases showed that NAG was a sensitive indicator of renal damage. This simple test may be valuable in detecting or monitoring renal disease.

Acetylglucosaminidase↗