Biomedical subjects

M Kihara

Publications and source records attributed to M Kihara.

333 records · Page 19Linked to original sources

PubMedDate not supplied

Humoral trophic influence on cardiovascular structural changes in hypertension.

Since the early development of structural cardiovascular change in spontaneously hypertensive rats (SHR) and stroke-prone SHR (SHRSP) indicated the involvement of non-pressure-dependent factors in this process in hypertension, smooth muscle cells (SMC) from the aorta of SHR, SHRSP, and normotensive Wistar-Kyoto rats (WKY) were investigated under tissue culture conditions free from blood pressure and humoral factors in vivo. By the observation of such factors as growth rate and DNA or protein synthesis vascular SMC from these rats with genetic hypertension were proved to have intrinsically greater growth activity independently of blood pressure. Although serum from SHR and SHRSP had no specific stimulative effect on SMC growth, circulating epinephrine may accelerate cardiovascular structural changes because isoproterenol added to the culture media enhanced ornithine decarboxylase (ODC) activity. Moreover, SMC from SHR and SHRSP showed greater thymidine incorporation than those from WKY even in response to lower extracellular Na+ concentration. Local nutritional conditions of SMC, which were proved to have a great effect on the morphology and structure of cultured SMC, may be a basic determinant of the development of hypertension-induced structural vascular changes or lesions.

Animals↗

PubMedDate not supplied

Permeability of intracranial extracerebral vessels in stroke-prone SHR.

Permeability of intracranial extracerebral arteries of stroke-prone spontaneously hypertensive rats (SHRSP) was studied using labeling techniques (ferritin and horseradish peroxidase), at the cellular level. In the arterial endothelial cells, the tracer molecules were slowly but constantly transported by the plasmalemmal vesicles to the subendothelial space. This endothelial transportation of the tracers into these cerebral arteries did not seem to be significantly influenced by aging, increased blood pressure, hyperlipidemia or the existence of cerebral bleeding and infarction. Around the adventitia, there were a great number of periadventitial capillaries, especially near bifurcations. In the periadventitial capillaries, the tracer molecules were readily trapped by endothelial cells and were quickly transported to pericapillary spaces. The tracer molecules were then detected in the phagocytes adjacent to the deeper layers of the media, and further in the medial smooth muscle cells. The possibility that large amounts of plasma components are supplied to the media from periadventitial capillaries in the intracranial extracerebral arteries has to be considered in the pathogenic mechanisms of cerebrovascular lesions.

Animals↗

PubMedDate not supplied

Increased transendothelial channel transport of cerebral capillary endothelium in stroke-prone SHR.

Permeability of brain capillaries of stroke-prone spontaneously hypertensive rats (SHRSP) was studied using labelling (horseradish peroxidase) and cytochemical techniques at the cellular level. In the cerebral capillary endothelium the tracer molecules were quickly transported by abundant transendothelial channels which directly connected the capillary lumen to the subendothelial space. Transendothelial channels are abundant and should be postulated as structural formations engaged in the increased transport of proteins across the capillary endothelium. Ultracytochemical studies revealed that the channels, bounded by indistinct delimiting membranes, initially had no acid phosphatase activity. With the passage of time, however, the channels showed acid phosphatase activity and were lined with distinct membranes. These observations suggested that the lysosomes might fuse with the transendothelial channels and might play an important part in the transport of macromolecules.

Acid Phosphatase↗

PubMedDate not supplied

Knowledge of and attitudes toward the pill: results of a national survey in Japan.

CONTEXT: After decades of debate, the oral contraceptive pill was legalized in Japan in June 1999. Because the pill had been unavailable up until then, little is known about the public's knowledge about, attitudes toward and intentions to use the pill. METHODS: In a nationwide probability sample, 630 women and men were interviewed in their homes in March 1999. Respondents were asked a range of questions to gauge their knowledge about and attitudes toward the pill. RESULTS: Most respondents (79%) could identify both the name and purpose of the birth control pill. Roughly the same proportion of respondents held an overall positive impression (44%) as held a negative impression (42%) of the pill, and 14% were undecided about the method. The pill's high level of effectiveness in pregnancy prevention was the most common reason for having a favorable impression of it (47%). Women were more concerned about side effects than were men, and they also knew more about the pill's potential side effects than did men. Only 12% of respondents said they intended to use the pill if it were approved. Roughly one-quarter (23-26%) did not correctly identify the pill's inability to protect against HIV and other sexually transmitted diseases (STDs). CONCLUSIONS: Legalization of oral contraceptives in Japan has led to an urgent need to educate both men and women on the inability of the pill to protect against STDs, including HIV Policymakers and providers need to recognize the importance of encouraging dual method use in Japan.

Adult↗

PubMedDate not supplied

Release of [3H]- and endogenous GABA from slices of the rat medulla oblongata: modification by 3-mercaptopropionic acid, nipecotic acid and diaminobutyric acid.

Slices of the rat medulla oblongata were superfused and electrically stimulated. The amount of [3H]- and endogenous GABA was determined. There was a stimulus-evoked release of [3H]- and endogenous GABA, which was Ca2+-dependent and tetrodotoxin-sensitive. 3-Mercaptopropionic acid (3-MP) reduced the release of endogenous GABA, whereas the release of [3H]-GABA was not affected by this agent. Nipecotic acid enhanced the spontaneous and stimulus-evoked release of both [3H]- and endogenous GABA. 3-MP, nipecotic acid and diaminobutyric acid modified the stimulus-evoked release of endogenous GABA from slices containing the rostral ventrolateral medulla, the caudal ventrolateral medulla or the nucleus tractus solitarii, regions responsible for blood pressure regulation. These results suggest that 3-MP inhibits the stimulus-evoked release of GABA without affecting its release process, whereas nipecotic acid enhances the release via its uptake inhibition action.

3-Mercaptopropionic Acid↗

PubMedDate not supplied

Effect of hydralazine-induced hypotension on glutamate, gamma-aminobutyric acid and some other amino acid levels in medullary regions of the rat.

Concentrations of glutamate, gamma-aminobutyric acid (GABA), glycine, beta-alanine and taurine were measured in microdissected areas of the rostral ventrolateral medulla (RVL), nucleus tractus solitarii (NTS) and caudal ventrolateral medulla (CVL) of the rat, and the effects of hydralazine-induced hypotension on the concentrations of amino acids were examined. All five amino acids were ubiquitously present in these brainstem regions. Hydralazine-induced hypotension increased glutamate levels in the NTS and CVL regions, but decreased GABA levels in all the regions studied. The level of glycine was decreased in the RVL region after hydralazine. Hydralazine decreased beta-alanine levels in the NTS and CVL regions. Electrical stimulation of slices containing the RVL region decreased glutamate levels but increased GABA levels in tissues. These results are compatible with the hypothesis that glutamate and GABA systems in these brainstem areas are related to blood pressure regulation.

Amino Acids↗

PubMedDate not supplied

Cardiovascular effects of GABA system activating drugs injected into the caudal ventrolateral medulla of the rat.

Drugs activating GABAergic systems were microinjected into the caudal ventrolateral medulla of the rat and effects on blood pressure and heart rate were investigated. In urethane-anesthetized rats, a dose-dependent increase in blood pressure and heart rate was induced by unilateral injections of GABA (30-300 ng) into the caudal ventrolateral medulla. Unilateral injections of the GABA receptor agonist muscimol (1-10 ng) and baclofen (0.1-10 ng) into the brainstem area also increased both the cardiovascular parameters. The GABA uptake inhibitors nipecotic acid (1-3 micrograms) and L-2,4-diaminobutyric acid (1 microgram), and the GABA-T inhibitor gamma-acetylenic GABA (1-3 micrograms) injected unilaterally into the brainstem area also produced hypertension and tachycardia. Bilateral microinjections of nipecotic acid (0.3 microgram) into the area potentiated the pressor and tachycardiac responses to carotid artery occlusion in pentobarbital-anesthetized rats. Lesioning of the rat nucleus tractus solitarii did not alter the GABA content in the lesioned side of the caudal ventrolateral medulla. The data provide further evidence that endogenous GABAergic mechanisms in the rat caudal ventrolateral medulla are involved in the regulation of blood pressure. It seems unlikely that the GABAergic mechanisms originate mainly from neurons in the nucleus tractus solitarii.

Animals↗

PubMedDate not supplied

Sudomotor dysfunction in amyotrophic lateral sclerosis.

We performed a quantitative sudomotor function test on 11 patients with classic amyotrophic lateral sclerosis (ALS) and 11 age-matched control subjects. Thermal warming increased the sweat rate in the forearm of ALS patients and in the forearm and thigh of control subjects. The sweat rate in the thigh of ALS patients was lower than that of controls. Thyrotropin releasing hormone increased the sweat rate in the forearm and thigh and decreased oral temperature in both ALS and controls but the lower extremity response was reduced in ALS. Results of the sudomotor axon reflex test on the thigh indicate that in ALS, there is mild postganglionic sudomotor dysfunction. We conclude that patients with ALS have mild thermoregulatory sweat dysfunction due to postganglionic lesions in the lower extremities.

Amyotrophic Lateral Sclerosis↗

PubMedDate not supplied

A case of neuro-Behçet's encephalitis with pleds as distinct from herpes simplex encephalitis: a differential diagnosis.

We report a male patient with neuro-Behçet's disease who had somnolence, mild motor aphasia and periodic lateralized epileptiform discharge. SPECT study showed decreased cerebral blood flow in the left frontal and temporal lobes. An MRI scan of the head showed only mild brain stem atrophy. His clinical signs were markedly improved after administration of prednisolone. We propose that some cases of neuro-Beh,cet's disease may have very similar clinical features to herpes simplex encephalitis and that SPECT and MRI examinations can be very useful in distinguishing the ischemic lesion of neuro-Behçet's from the inflammatory lesion of herpes simplex encephalitis.

Behcet Syndrome↗