Recombinant rat guanidinoacetate methyltransferase: structure and function of the NH2-terminal region as deduced by limited proteolysis.

Recombinant rat liver guanidinoacetate methyltransferase, a monomeric protein with Mr 26,000, is inactivated upon incubation with low concentrations of trypsin. Examination of the reaction products by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and high-performance liquid chromatography followed by amino acid analysis and sequencing of isolated peptides reveals that the inactivation is due to the cleavage of the NH2-terminal segment after Arg20. The cleaved peptide is not tightly associated with the rest of the protein.

Hydroxylation of o-halogenophenol and o-nitrophenol by salicylate hydroxylase.

Salicylate hydroxylase [EC 1.14.13.

Electron-microscopic observations of the alveolar brush cell of the rat.

The alveolar brush cells in the rat lung were observed by transmission electron microscopy. The general structural features of the brush cells in this report were basically in agreement with earlier descriptions. However, this report is the first to detect long, thick microvilli with a unique form protruding into the alveolar lumen in parallel with the basement membrane, not vertically to the basement membrane.

Site-directed mutagenesis of rat liver S-adenosylhomocysteinase. Effect of conversion of aspartic acid 244 to glutamic acid on coenzyme binding.

Aspartic acid 244 that occurs at the putative NAD(+)-binding site of rat liver S-adenosylhomocysteinase was replaced by glutamic acid by oligonucleotide-directed mutagenesis. The mutant enzyme was purified to homogeneity as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Gel permeation chromatography showed that the purified mutant enzyme was a tetramer as is the wild-type enzyme.

Effect of sodium intake on the hypotensive effect of calcium antagonists.

To clarify the influence of Na balance on the hypotensive effect of calcium antagonists, the changes of blood pressure and humoral factors after a single oral administration of 40 mg nicardipine were evaluated in 15 subjects with essential hypertension under high, normal, and low Na regimens (mean 24 hour urinary Na excretion: 320 +/- 24, 147 +/- 7, 27 +/- 6 mEq, respectively). Nicardipine induced a significant reduction of mean blood pressure and increase in heart rate. The change of mean blood pressure after nicardipine was negatively related to the pretreatment mean blood pressure under the three levels of Na intake (p less than 0.

Fixed drug eruption. Expression of epidermal keratinocyte intercellular adhesion molecule-1 (ICAM-1).

The pathogenic mechanism of preferential localization to certain skin sites of fixed drug eruption lesions has remained unknown. Skin biopsy specimens were obtained from four patients with fixed drug eruptions at various time points after final exposure to the causative drug and were studied immunohistologically using monoclonal antibodies to intercellular adhesion molecule-1 (ICAM-1), lymphocyte function-associated antigen-1, and HLA-DR. The expression of ICAM-1 by keratinocytes was confined exactly to the involved epidermis.

Expression of rat liver S-adenosylhomocysteinase cDNA in Escherichia coli and mutagenesis at the putative NAD binding site.

The cDNA for rat liver S-adenosylhomocysteinase has been cloned, and the nucleic acid sequence has been determined. By comparison of the deduced amino acid sequence for S-adenosylhomocysteinase with that of the dinucleotide binding region for other proteins, the sequence from amino acids 213 to 244 in rat liver S-adenosylhomocysteinase was proposed to be part of the NAD binding site (Ogawa, H., Gomi, T.

Human liver serine dehydratase. cDNA cloning and sequence homology with hydroxyamino acid dehydratases from other sources.

Rat liver serine dehydratase cDNA was used to screen a human liver cDNA library in lambda gt11. One positive clone occurred in every 5,000 clones. Fifteen positive clones were plaque purified.

Effects of OKY-046, a selective thromboxane synthetase inhibitor, on blood pressure and thromboxane synthesis in spontaneously hypertensive rats.

The effects of OKY-046, a specific thromboxane (TX) synthetase inhibitor, on blood pressure, urinary TX excretion, TX synthesis in blood platelets, kidney slices and aortic strips, were evaluated in adult spontaneously hypertensive rats (SHR). OKY-046 was dissolved in drinking water at concentrations of 1, 10, 100 mg/dl. The average intakes of OKY-046 were 1.

Alteration of vascular thromboxane in rats with subtotal renal ablation.

To assess the roles of vascular prostaglandins in the hypertension of chronic renal failure, the release of prostacyclin and thromboxane (TX) from aorta was evaluated in male Sprague-Dawley rats, the renal mass of which was reduced by removing one kidney and two-thirds of the contralateral kidney ("5/6 nephrectomy"). Five-sixths nephrectomy was followed by significant rises in serum creatinine to 0.55 +/- 0.

Participation of the sympathetic nervous system in hypertension in rats with subtotal renal ablation.

To clarify the role of the sympathetic nervous system in the development of hypertension in chronic renal failure, plasma levels and urinary excretions of catecholamines were evaluated in male Sprague-Dawley rats. The renal mass of the rats was reduced by removing one kidney and two-thirds of the contralateral kidney (5/6 nephrectomy). Five-sixths nephrectomy was followed by significant increases in serum creatinine (to 0.

Effect of sodium restriction on platelet function in patients with essential hypertension.

The effects of sodium intake on blood pressure and platelet function were evaluated in 19 subjects with essential hypertension (10 men and 9 women; mean age 49.7 years). The study was conducted under 3 conditions: (1) normal sodium diet (12 g/day of salt was used in cooking), (2) after 5 days of mild sodium restriction diet (6 g/day of salt was used in cooking) and (3) after moderate sodium restriction (no salt was used in cooking).

In vitro migration of L3T4+ cloned T cells to epidermis: possible role for keratinocyte-derived factors.

Three types of L3T4+ cloned T cells with different antigen specificities, auto-, allo-, and antigen-reactive, were characterized with respect to their migratory potential using an in vitro migration assay under agar gel. Autoreactive T cells, BB5, and alloreactive T cells, SK 1, both of which have been proved to be epidermotropic in vivo, showed specific directional migration to the epidermis, whereas no directional migration was seen with non-epidermotropic cloned T cells and freshly isolated lymph node T cells. Both BB5 and SK 1 cells were equally attracted to all the epidermal fragments tested regardless of their I-A antigens.

Rat liver S-adenosylhomocysteinase. Spectrophotometric study of coenzyme binding.

Rat liver S-adenosylhomocysteinase, a homotetramer, was resolved by treatment with acid ammonium sulfate into apoenzyme and NAD. The apoenzyme thus prepared retained a tetrameric structure but differed in the mobility on nondenaturing polyacrylamide gel electrophoresis. The inactive apoenzyme was reactivated upon incubation with NAD.

Captopril, an angiotensin I-converting enzyme inhibitor, decreases proteinuria in hypertensive patients with renal diseases.

A crossover study was planned in order to compare the effects of captopril and slow channel calcium entry blocker (Ca antagonist) on urinary protein excretion in 7 hypertensive patients with renal diseases, including 4 with IgA nephropathy, 2 with lupus nephritis and 1 with benign nephrosclerosis. Captopril decreased urinary protein excretion by 52% without any change in creatinine clearance, while Ca antagonist was having a slight effect on proteinuria even though the drug showed an equivalent antihypertensive effect as captopril. These results suggest that the attenuation of proteinuria induced by captopril may be related to an inhibition of angiotensin II formation and/or a direct action of this drug on protein permeability of glomerular basement membrane.

Relationship between transient DNA hypomethylation and erythroid differentiation of murine erythroleukemia cells.

The state of DNA methylation in mouse erythroleukemia (MEL) cells has been analyzed in relation to commitment to differentiation in response to treatment with hexamethylenebisacetamide (HMBA). Previous experiments have shown that induction by HMBA involves transient genome-wide hypomethylation of DNA that is achieved by replacement of 5-methylcytosine with cytosine residues. The experiments described in the present communication revealed that hypomethylation is a very early event in the process of differentiation.

Plasma beta-thromboglobulin to platelet factor 4 ratios as indices of vascular complications in essential hypertension.

The ratio of the plasma level of beta-thromboglobulin (beta-TG) to platelet factor 4 (PF-4) which is regarded as a most reliable indicator of platelet activation in vivo, was followed in 52 subjects at various stages of essential hypertension according to the WHO classification. These comprised 30 cases at stage I, 19 cases at stage II and three cases at stage III, and 20 age-matched normotensive control subjects. The observed beta-TG:PF-4 ratio in the hypertensive patients was 4.

Effects of guanfacine monotherapy on blood pressure, heart rate, plasma renin activity, aldosterone, and catecholamines in hypertensive patients with chronic glomerulonephritis.

Effects of guanfacine, a centrally acting antihypertensive, on blood pressure, heart rate, plasma renin activity, serum aldosterone, plasma norepinephrine, and renal function were evaluated in 16 patients with hypertension with biopsy-proved chronic glomerulonephritis. Guanfacine monotherapy with a daily dose of 1 to 2.5 mg at bedtime for 6 months brought about a significant reduction in blood pressure (171 +/- 2/110 +/- 2 to 144 +/- 2/89 +/- 1 mm Hg; P less than 0.

Molecular cloning, sequence analysis, and expression in Escherichia coli of the cDNA for guanidinoacetate methyltransferase from rat liver.

Five cDNA clones encoding rat liver guanidinoacetate methyltransferase (S-adenosyl-L-methionine: guanidinoacetate N-methyltransferase, EC 2.1.1.

Amino acid sequence of S-adenosyl-L-homocysteine hydrolase from rat liver as derived from the cDNA sequence.

Rat liver cDNA libraries constructed in lambda gt11 were screened for reactivity with polyclonal antibodies to native S-adenosyl-L-homocysteine (AdoHcy) hydrolase (adenosylhomocysteinase; EC 3.3.1.