Search PubMed⌕ Search

Biomedical subjects

M Hirayama

Publications and source records attributed to M Hirayama.

At least 127 records · Page 7Linked to original sources
PubMed1995

[Changes in hearing features according to days from onset of sudden deafness].

We analyzed 746 patients with idiopathic sudden hearing loss who visited our clinic within 16 days after the onset. Patients were divided into 10 groups according to the number of days between the initial visit and the onset. Initial hearing levels, audiometric types and hearing recoveries were investigated in these groups to estimate the natural history of sudden deafness. The results were as follows: 1) There were no significant differences among the 10 groups regarding the averaged five-frequency hearing levels of initial audiograms. 2) Regarding the audiometric types of the initial audiograms, flat and upward slope types were frequently seen in the groups who visited us within 6 days. In contrast, the population of down slope types gradually increased in the groups presenting after 7 days. In the ultimate audiograms, flat and down slope types were frequently seen in all groups. 3) There were significant differences among the 10 groups regarding the averaged five-frequency improvement (one-way analysis of variance, p < 0.01). After 9 days, hearing recovery became less likely.

Hearing↗
PubMed1995

Acute hemolysis during cyclosporine therapy successfully treated with vitamin E.

The immunosuppressant cyclosporine induces acute hemolysis (hemolytic uremic syndrome) in some patients after transplantation, possibly because of its effects on the vascular endothelium. We report a case of Coombs-negative, non-immune severe hemolytic anemia during cyclosporine therapy after allogeneic bone marrow transplantation for severe aplastic anemia. Uremia was not observed. Vitamin E was effective in treating the intravascular hemolysis.

Acute Disease↗
PubMed1994

Isolation and characterization of alginate-derived oligosaccharides with root growth-promoting activities.

Lytic digestion of poly(mannuronate), poly(guluronate), and alginate with an alginate lyase from Alteromonas macleodii was used to prepare mixtures of unsaturated oligosaccharides. Four oligosaccharides isolated from the alginate lyase-lysate by anion-exchange chromatography on Q-Sepharose were found to be the major components of the root growth-promoting lysate. The oligosaccharides were analyzed by NMR and SIMS and identified as di- and tri-saccharides having O-(4-deoxy-L-erythro-hex-4-enopyranosyluronic acid)-1--> at the nonreducing terminus. The trisaccharides from the lysate were found to have root growth-promoting activity in a barley bioassay.

Alginates↗
PubMed1994

TGF-beta mediates natural suppressor activity of IL-2-activated lymphocytes.

In addition to generating cells with non-MHC-restricted cytotoxic activity that is characteristic of lymphokine-activated killer (LAK) cells, in vitro cultures of lymphocytes with relatively high concentrations of IL-2 generate cells that simultaneously exhibit two distinct types of suppressor activities: veto, the ability of cells to specifically suppress generation of allo-CTL against their own histocompatibility Ags; and natural suppression, the ability of these same cells to nonspecifically suppress the generation of allo-CTL against both their own and unrelated cell surface Ags. In contrast to veto, which is known to require cell-cell contact between veto-active cells and precursors of CTL, natural suppression is known to be mediated by soluble factors. To identify and characterize suppressor factors that might mediate the natural suppressor activity of IL-2-activated lymphocytes, murine spleen cells were cultured with 1000 U/ml IL-2, and, after varying periods of incubation, their LAK cytolytic activity and natural suppressor activity was determined and cell supernatants were collected and tested for their effects on mixed lymphocyte culture-induced generation of allo-CTL. Like the IL-2-activated lymphocytes themselves, supernatants of these cells nonspecifically inhibited mixed lymphocyte culture-induced generation of allo-CTL. Rabbit anti-TGF-beta specifically neutralized the suppressive effects of both LAK cell supernatants and the IL-2-activated lymphocytes themselves. These findings indicate that TGF-beta is the primary mediator of the natural suppressor activity of IL-2-activated lymphocytes.

Animals↗
PubMed1994

Effects of caffeine and casein phosphopeptides on fertilization in vitro of pig oocytes matured in culture.

Two experiments were conducted to assess the effects of caffeine and casein phosphopeptides (CPPs). One experiment tested the ability of frozen-thawed epididymal spermatozoa from boar (A, B, C), of proven low in vitro fertilization rates, to penetrate pig follicular oocytes. The other experiment tested the ability of ejaculated spermatozoa to uptake Ca2+. In Experiment 1, oocytes matured in vitro were inseminated with spermatozoa (Boar A) in medium that contained 0, 2, 5, 10, 15, and 20 mM caffeine and CPPs (1 mg/ml), or in medium that contained the same caffeine concentrations without CPPs. When CPPs were added to the caffeine-containing medium, significantly higher penetration rates were obtained than when the oocytes were inseminated in the CPPs-free medium. When the oocytes were inseminated with the spermatozoa (Boar A, B, C) in medium that contained 5 mM caffeine and dephosphorylated CPPs (dCPP:1 mg/ml), the penetration rate was significantly lower than when the oocytes were inseminated with the spermatozoa in medium containing 5 mM caffeine and CPPs (1 mg/ml). In Experiment 2, the concentration of Ca2+ in ejaculated spermatozoa of proven low in vitro fertilization rates during incubation in the fertilization medium was determined with fluorescence, Fura2/AM. When the medium contained CPPs, the intracellular concentration of Ca2+ in spermatozoa increased with a peak of 113 nM after 90 min of incubation. The concentration of Ca2+ was gradually decreased in the medium without CPPs. However, addition of CPPs in the medium had no effect on the motility of spermatozoa in Experiments 1 and 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

A radiological analysis of heart sympathetic functions with meta-[123I]iodobenzylguanidine in neurological patients with autonomic failure.

Cardiac scintigraphy with meta-[123I]iodobenzylguanidine (MIBG) is used to assess cardiac sympathetic function. We performed [123I]MIBG scintigraphy in 7 patients with neurological diseases presenting orthostatic hypotension and other autonomic failures (AF), 22 neurological patients without AF, and 9 healthy subjects. Thallium scintigraphy and echocardiography were also performed in all subjects. In this series, patients with any evidence of cardiac dysfunction were excluded. No [123I]MIBG accumulation was observed in all patients with AF, and cardiac defects were noted in 7 patients (5 with Parkinson's disease [PD], 2 with spinocerebellar degenerations [SCD]), and in some patients without AF. In contrast, the distribution of [123I]MIBG was normal in all the healthy subjects. No decrease in [123I]MIBG accumulation was resulted from drug therapy (droxidopa, amezinium and thyrotropin-releasing hormone). In conclusion, reduced accumulation on [123I]MIBG scintigraphy may be due to myocardial beta-adrenoceptor dysfunction or reduced central sympathetic activity of the heart, or both.

3-Iodobenzylguanidine↗
PubMed1994

Cultural views of breastfeeding among high-school female students in Japan and the United States: a survey.

This study compares the attitudes toward breastfeeding of high-school students in Japan and the United States. The study was conducted as a cross-sectional survey with a convenience sample (N = 329). Data were collected in 1989 and 1990 at two private, girls-only high schools (Tokyo, Japan and Farmington, Michigan). Retrieval rates were 100 percent (Tokyo) and 78 percent (Michigan) respectively. Responses were compared by the chi-square (chi 2) test with Yate's correction and factor analyses. Tokyo students perceived that their mothers talked positively about breastfeeding (54 percent), while only 17 percent of Michigan students reported that their mothers did so (< .001). Less than five percent of the Tokyo students felt that breastfeeding disturbs family life, whereas nearly 98 percent of the Michigan students felt so (p < .001). Tokyo students scored significantly higher on the 'family' factor, while the Michigan students scored significantly higher on the 'self' factor. Overall, this study indicates that high school students in Japan have more positive attitudes toward breastfeeding than students in the United States; however, teenagers in the United States are more interested than their Japanese age-mates in gaining information about breastfeeding.

Adolescent↗
PubMed1994

Investigation of pure-tone hearing levels at a single frequency in sudden deafness.

Hearing levels in patients with sudden deafness are commonly discussed in terms of average thresholds at 3 or 5 frequencies, but an investigation of hearing levels at a single frequency is also important. In this paper, pure tone thresholds at 500 Hz and 4,000 Hz were investigated in patients with sudden deafness who came to our clinic within 4 days of onset. Particular attention was paid to the relationship between audiometric types according to the contour of the initial loss and degree of hearing recovery at each frequency. In the group of patients whose initial hearing level at 500 Hz was between 55 and 70 dB, the hearing recovery at 500 Hz in the upward slope type was significantly greater than that in the downward slope type, but in other groups no significant differences in hearing recovery were observed among the different types of initial audiograms. We considered that the hearing recovery at a single frequency was not related to the audiometric type except in the patients with the upward slope type with moderate hearing loss.

Adolescent↗
PubMed1994

Study on the distribution of hearing levels in idiopathic bilateral sensorineural hearing loss.

The pattern of aggravation in hearing was investigated in 105 patients who were diagnosed as having idiopathic bilateral sensorineural hearing loss at the Hearing Loss Clinic, Department of Otolaryngology, Kitasato University Hospital. Audiograms were taken 1,069 times from the 105 cases over more than 3 years, and were used to obtain the distribution of hearing levels at each test frequency. The clinical course of idiopathic bilateral sensorineural hearing loss was divided into three stages: Stages I, II and III, based on the pattern of aggravation. The pattern of distribution of hearing levels at different stages was compared with each other with reference to peaks or clustering points. Similar peaks were noted at Stage II and Stage III as aggravation proceeded from Stage I. Another peak was noted in the zone of scale-out.

Adolescent↗
PubMed1993

Regulation of iron metabolism in HepG2 cells: a possible role for cytokines in the hepatic deposition of iron.

In chronic inflammation it is reported that serum iron is depleted and hepatic iron is increased because of reticuloendothelial system iron blockade. However, recent studies indicate that hepatic parenchymal cells increase the uptake of transferrin-bound iron after in vivo stimulation with bacterial lipopolysaccharide, suggesting that endotoxemia itself or lipopolysaccharide-induced production of inflammation-related cytokines may also be responsible for this phenomenon. In this study the actions of inflammation-related cytokines on the synthesis of iron-binding proteins (transferrin and ferritin) and transferrin receptor and the uptake of transferrin-bound iron were investigated in a human hepatoblastoma cell line, HepG2, which is the most commonly used cell line for examining the regulation of hepatic protein synthesis by cytokines. The cells were exposed to interleukin-1 beta, interleukin-6 or tumor necrosis factor-alpha separately for 24 hr. In each cytokine treatment group, the level of transferrin, which is secreted into the conditioned medium, was found to be decreased compared with that of untreated cells. On the other hand, the biosynthesis of ferritin was markedly elevated after the same treatment. This increase in ferritin by cytokine treatment was diminished when deferoxamine was used concomitantly to deplete intracellular chelatable iron. After stimulation with interleukin-1 beta, interleukin-6 or tumor necrosis factor-alpha, 59Fe-labeled transferrin uptake into the cells was increased by 36%, 48%, or 18%, respectively, and this uptake was inhibited by the addition of excess unlabeled transferrin. A binding study with 125I-labeled diferric transferrin revealed that the three cytokines increased the number of transferrin receptors on the cell surface by 1.15-fold to 1.35-fold.(ABSTRACT TRUNCATED AT 250 WORDS)

Carcinoma, Hepatocellular↗
PubMed1993

Treatment of postprandial hypotension with selective alpha 1 and beta 1 adrenergic agonists.

In order to treat postprandial hypotension (PPH), we orally administered a combination of denopamine (10 mg, a selective beta 1-adrenergic agonist) and midodrine-HCl (4 mg, a selective alpha 1-adrenergic agonist) to eight patients with autonomic failure (AF) prior to and after eating. When the patients were given 75 g glucose with 225 ml water without drugs, blood pressure fell subsequently, cardiac output (CO) was unchanged, and vascular resistance of the lower legs (LVR) decreased. However, concomitant administration of denopamine and midodrine-HCl prevented PPH and increased CO and LVR. The portal blood flow was not indifferent to the drugs. A marked increase in heart rate after drug administration was seen in some patients with AF, which reflects the supersensitivity to denopamine. Combined oral administration of denopamine and midodrine-HCl is a safe and useful therapy for PPH in patients with AF.

Adrenergic alpha-Agonists↗
PubMed1993

Postprandial hypotension: hemodynamic differences between multiple system atrophy and peripheral autonomic neuropathy.

To clarify the mechanism of postprandial hypotension (PPH), we performed hemodynamic investigation after oral glucose ingestion in ten patients with multiple system atrophy (MSA), three patients with peripheral autonomic neuropathy (PN) and 16 normal controls. Blood pressure (BP) and heart rate (HR) were measured with an automatic sphygmomanometer; cardiac out (CO) and lower leg blood flow (LBF) with impedance plethysmography; and portal blood flow (PBF) using a B-mode pulse Doppler. In normal subjects, BP, LBF and vascular resistance of the lower leg (LVR) were not changed, but HR slightly increased, and PBF and CO significantly increased after oral ingestion of 75 g glucose. In the patients with MSA, BP fell significantly 15 min after glucose ingestion, and HR and CO did not increase. PBF and LBF increased and LVR fell significantly. In PN patients, BP decreased at 15 min after glucose ingestion, but soon recovered. Increase of PBF and decrease of LVR in them were almost similar to those in the MSA group, and increase of CO was greater than that in the controls. These results suggest that both systemic vasodilatation (presumably due to gastrointestinal vasodilatatory peptides) and lack of compensatory increase of CO and LVR play important roles in PPH.

Administration, Oral↗