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Biomedical subjects

M Hiruma

Publications and source records attributed to M Hiruma.

At least 109 records · Page 6Linked to original sources
PubMed1987

Contribution of renal angiotensin converting enzyme (ACE) to blood pressure regulation: possible role of brush border ACE.

The role of renal angiotensin converting enzyme (ACE) in blood pressure regulation is not well understood. In our studies, both acute and chronic treatment of hypertensive rats SHR and SHRSP with ACE inhibitors Enalapril and SA446 had a blood pressure lowering effect that coincided with an inhibition of renal cortical and aortic ACE, but not plasma ACE. Further, ACE activities in the renal cortex and aorta were found to increase with aging of the SHRSP, therefore concomitantly with hypertension development. In the kidney, brush border membranes (BBM) contained abundant ACE. We found that the activities of ACE in the renal cortex closely correlated to the activities in isolated BBM, in Wistar Kyoto rats and in the SHRSP. Thus, renal cortical ACE activity and blood pressure correlated in cases of ACE inhibition and hypertension development. Since the ACE activity in the renal cortex appeared to reflect the enzyme activity in BBM, the brush border ACE may have to be taken into account, in view of the relationship between renal ACE and blood pressure.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1986

Rat atrial natriuretic factor stimulates renin release from renal cortical slices.

We investigated the effect of synthetic rat atrial natriuretic factor (ANF) on renin release from rat renal cortical slices. Rat ANF (10(-6) M) increased renin release from the slices with a concomitant increase in the levels of cGMP contents. The increase in cGMP was also prominent in the case of incubation with 10(-4) M sodium nitroprusside but was not accompanied by an enhanced release renin. 8-Bromo-cGMP did not stimulate renin release. We propose that the stimulation of renin release from rat renal cortical slices is not related to an increase in endogenous cGMP.

Animals↗
PubMed1986

Effects of hyperthermia on phagocytosis and intracellular killing of Sporothrix schenckii by polymorphonuclear leukocytes.

The effects of hyperthermia on phagocytosis and killing of Sporothrix schenckii by polymorphonuclear leukocytes (PMNs) were investigated in order to clarify the mechanism of local thermotherapy for sporotrichosis. Yeast cells of S. schenckii, PMNs and serum were incubated at 37 degrees C or 40 degrees C for 2 or 4 hours. Rate of phagocytosis and killing rate (rate of germination) were estimated, and their processes were observed by transmission electron microscopy. There was no effect of hyperthermia on the phagocytosis rate, but the killing rate increased significantly at 40 degrees C. Electron microscopic examination showed an increase of granularity in the yeast cytoplasm, elongation and fragmentation of the cell membrane. The ultrastructural changes were basically identical under both temperatures, but the degree of these changes was higher at 40 degrees C than at 37 degrees C. Although both intact and degenerated yeasts were found in the same conditions, their transient forms were few, suggesting that the PMN-killing process was completed promptly.

Hot Temperature↗
PubMed1986

Angiotensin converting enzyme (ACE) in the kidney: contribution to blood pressure regulation and possible role of brush-border ACE.

With regard to the concept of the local action of the renin angiotensin system (RAS) involved in blood pressure regulation, the presence of angiotensin converting enzyme (ACE) in a variety of organs suggests that locally produced angiotensin II (ANG II) shares, at least to some extent, the actions of this peptide on respective target organs of ANG II. However, renal ACE is less well understood for its relationship between blood pressure and enzyme activity. In our present studies, with a single oral administration of enalapril to spontaneously hypertensive rats, the inhibition of renal cortical and aortic ACE, but not plasma ACE, coincided with a reduction in blood pressure. Development of high blood pressure in stroke-prone, spontaneously hypertensive rats (SHRSP) from 7 to 22 weeks of age was accompanied by an increase in ACE activity in the renal cortex. Aortic and pulmonary ACE also tended to increase with age, but was less prominent. Isolated brush-border membranes contained abundant ACE, both in Wistar-Kyoto rats and SHRSP, and the levels of ACE in renal cortical homogenates closely correlated to the levels of brush-border ACE. Thus, changes in renal cortical ACE activity in response to the ACE inhibition and in cases of SHRSP in relation to aging are apparently associated with changes in blood pressure. It is likely that renal cortical ACE activity reflects the enzyme activity in the brush borders. Thus, brush-border ACE should probably be taken into account when discussing possible roles of renal ACE.

Aging↗
PubMed1985

Ultrastructure of Cryptococcus neoformans in the cerebrospinal fluid of a patient with cryptococcal meningitis.

The ultrastructure of Cryptococcus neoformans in the cerebrospinal fluid, which was obtained from a patient suffering from systemic lupus erythematosus and cryptococcal meningitis, before treatment and on the 10th and 20th day after the start of treatment was studied. Numerous cryptococci were detected in their cerebrospinal fluid before treatment. However, in most of them their biological activity was low and their organelles were not clear. A few yeasts preserved well their organelles. Such cells showed a tendency to develop vesicular membrane structures (lomasomes) touching the internal part of the cell wall. In the cerebrospinal fluid on the 20th day all of the yeasts were dead, even though numerous yeasts were observed by an India-ink method. At this time no colonies were recovered from the fluid.

Adult↗
PubMed1983

The effects of heat on Sporothrix schenckii in vitro and in vivo.

In order to clarify the mechanism of action of topical thermotherapy on sporotrichosis, the effects of heat on Sporothrix schenckii in vitro and in vivo were investigated by observing the percentage germination and the ultrastructure. When the spores were heated to 42 degrees C, it took 10 hr with the conidia, 2 hr with the yeast-like cells and 1 hr with the spores in vivo to reduce the germination rates to 10%. The percentage germination curves were reduced slowly at first but later exponentially. Changes in the ultrastructure became evident in 2 hr with the yeast-like cells and in 8 hr with the conidia. The ribosome count declined and amorphous dense materials appeared in the cytoplasm and mitochondria. In vivo, the outstanding feature of the heated spores was the diversity of internal ultrastructural changes encountered and morphological changes. These were observed at 1 hr post treatment.

Hot Temperature↗