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J J Helwig

Publications and source records attributed to J J Helwig.

68 records · Page 4Linked to original sources
PubMed1978

Purification and some properties of tartrate-sensitive acid phosphatase from rabbit kidney cortex.

Two forms of tartrate-sensitive acid phosphatases (EC 3.1.3.2) were purified from rabbit kidney cortex by a multiple-column-chromatography method. The basic form constituted 90% of the enzyme and migrated as a single band of protein on polyacrylamide-gel electrophoresis. The proteins contaminating the acidic form did not exceed 5% of the total protein. The specific activity towards p-nitrophenyl phosphate was 12 mumol/min per mg for the basic form and 0.7 mumol/min per mg for the acidic form. The basic form of the enzyme differs from the acidic form in its heat-stability, Km values, inhibition rates by tartrate and fluoride and substrate specificities. Relative to p-nitrophenyl phosphate hydrolysis rate, the acidic form hydrolysed a variety of physiological monophosphate esters, whereas the basic form hydrolysed only CMP and phosphoenolpyruvate. Bacterial neuraminidases had no effect on the activity and mobility of the acidic form on polyacrylamide-gel electrophoresis. Both forms have the same molecular weight (101000 +/- 4000) and are probably composed of two identical subunits. The question whether the two forms of the enzyme are different proteins or whether one is a modified form of the other is discussed.

Acid Phosphatase↗
PubMed1977

Purification and some properties of arylsulphatases A and B from rabbit kidney cortex.

Arylsulphatases A and B (EC 3.1.6.1) of rabbit kidney cortex were purified 5250- and 7720-fold respectively by a multiple-column-chromatography method. The specific activity toward 4-nitrocatechol sulphate was 42mumol/min per mg for arylsulphatase A and 62 mumol/min per mg for arylsulphatase B. Each enzyme migrated as a single band on polyacrylamide-gel electrophoresis, and the enzyme activity corresponded to the band of protein on the gel. The rate of hydrolysis of ascorbic acid 2-sulphate by arylsulphatase A was three times that for cerebroside 3-sulphate. Arylsulphatase B hydrolysed UDP-N--acetylgalactosamine 4-sulphate and glucosamine 4,6-disulphate, but not galactosamine 6-sulphate.

Animals↗
PubMed1977

[Experimental nephrotic syndrome in the rat. Biologic parameters and study of several hydrolases in different purified kidney fractions].

The induction of nephrotoxic nephritis in rats with rabbit antibodies preparation results in proteinuria, hypoproteinemia and hyperlipidemia with little glomerular lesions. A study of some hydrolases in cortex and medulla on one hand and glomerular and tubules on the other, showed changes in the activities of following enzymes. 1) A 20-30 % decrease in Na+, K+ dependent ATP-ase in whole kidney. 2) A 20 % decrease in beta-galactosidase activity in glomerular and medulla. 3) A 20 % increase of arylsulphatase A activity in tubules. These results are discussed in the light of the present knowledge of sulphatide metabolism in kidney.

Animals↗
PubMed1975

Renal cortex guanylate cyclase. Preferential enrichment in glomerular membranes.

1. The localisation and some of the properties of rabbit kidney cortex guanylate cyclase (GTP pyrophosphatase lyase (cyclizing) EC 4.6.1.2) have been studied. Upon fractionation of dissociated renal cortex, guanylate cyclase activity was preferentially enriched in fractions of pure glomeruli, where its specific activity was 44.5 times that measured in tubular fragments. Most, if not all, of the glomerular activity was found to be firmly membrane-bound, whereas the guanylate cyclase activity of the tubules was mainly soluble. Therefore, particulate guanylate cyclase activity could serve as marker enzyme for kidney glomeruli. 2. All hormones or hormone-like agents tested were without effect on kidney guanylate cyclase activity. Triton X-100 stimulated both glomerular and tubular activity. 3. Considering the high cyclic GMP forming capacity of kidney glomeruli, part of the cyclic GMP found in urine might be synthetized locally in these structures.

Animals↗
PubMedDate not supplied

Isolation and characterization of a microvascular fraction from rabbit kidney cortex.

Collagenasic dispersion of rabbit kidney cortex followed by centrifugation on discontinuous sucrose gradient, allowed the simultaneous isolation of a microvascular fraction and of glomerular and tubular fractions. The microvessels were characterized by an overall diameter of 22 micron and the presence of granular and smooth muscle cells. Measurement of cellular renin activity and the muscle specific enzyme creatine kinase showed that these vessels were arteriolar in nature and that they contained the preglomerular arterioles. The glomerular or tubular contamination rates were assessed by means of enzymatic markers. Thus, in the arterioles, potassium fluoride-resistant acid phosphatase was some 10 times lower than in the glomeruli. The specific tubular enzymes gamma-glutamyl-transpeptidase and alkaline phosphatase were about 20 times lower in the arterioles than in the tubular fraction. The possibility of obtaining these fractions may facilitate many types of study on renal hemodynamic and glomerulo-tubular feedback control.

Acid Phosphatase↗
PubMedDate not supplied

[Are serum acid phosphatase levels of diagnostic significance in prostatic cancer? (author's transl)].

The abnormal serum level of "prostatic" acid phosphatases, stresses a cellular alteration but without an own specificity allowing to certify that it is related to a prostatic affection. One could expect that during the following years thanks to the immunological and electrophoretic methods one can be able to detect in serum specific enzymes issued from a tissue which is in a definite physiopathological state.

Acid Phosphatase↗
PubMedDate not supplied

[Nitric oxide (NO) and normal and pathologic renal development].

Nitric oxide (NO) has been identified as the mediator accounting for the biological effects of endothelium-derived relaxing factor (EDRF) and has been shown to be generated by the action of constitutive and inducible NO-synthases (NOSs) from L-arginine in a variety of cells, including macrophages, neurons and endothelial cells. NO acts as an autocrine or paracrine mediator, its half-life being very short, within the range of few seconds. The NO produced in endothelial cells exerts potent, regional vasodilatatory effects. In the kidney, NO has been shown to play a key role in various processes in normal and pathological conditions. NO is involved in the control of renal basal vascular tone and the maintenance of low vascular resistance. Increasing data suggest that NO interacts with the renin angiotensin system to ultimately influence renal haemodynamic function.

Animals↗