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Biomedical subjects

Y Honda

Publications and source records attributed to Y Honda.

At least 19 recordsLinked to original sources
PubMed1992

Antibody to the inositol trisphosphate receptor blocks thimerosal-enhanced Ca(2+)-induced Ca2+ release and Ca2+ oscillations in hamster eggs.

The sulfhydryl reagent thimerosal enhanced the sensitivity of hamster eggs to injected inositol 1,4,5-trisphosphate (InsP3) or Ca2+ to generate regenerative Ca2+ release from intracellular pools. A monoclonal antibody (mAb) to the InsP3 receptor blocked both the InsP3-induced Ca2+ release (IICR) and Ca(2+)-induced Ca2+ release (CICR). The mAb also blocked Ca2+ oscillations induced by thimerosal. The results indicate that thimerosal enhances IICR sensitized by cytosolic Ca2+, but not CICR from InsP3-insensitive pools, and causes repetitive Ca2+ releases from InsP3-sensitive pools.

Animals↗
PubMed1992

Relapsing acute disseminated encephalomyelitis associated with chronic Epstein-Barr virus infection: MRI findings.

A 25-year-old women had a fever, left cervical lymphadenopathy, neurological symptoms and signs, CSF pleocytosis and persistent high serum antibodies to the Epstein-Barr virus (EBV); she had a recurrence 1 year later. She was thought to have relapsing acute disseminated encephalomyelitis associated with chronic EBV infection. MRI revealed abnormalities, mainly in the right basal ganglia and left midbrain. At the time of the recurrence, further abnormalities appeared in the opposite basal ganglia and right cerebral white matter.

Adult↗
PubMed1992

Detection of varicella-zoster virus DNA by polymerase chain reaction in cerebrospinal fluid of patients with herpes zoster meningitis.

In three of five patients with herpes zoster meningitis, varicella-zoster virus (VZV) DNA was detected by the polymerase chain reaction (PCR) in the initial samples of cerebrospinal fluid. DNA fragments of group A or B, following classification of VZV strains by the size of the variable region IV of VZV genome, were found at the 7th, 10th and 24th illness day in the three positive cases: one of these cases did not have skin lesions. These results suggest that the detection of VZV DNA by PCR is useful for the diagnosis of herpes zoster meningitis, as well as for its molecular epidemiology.

Adult↗
PubMed1992

Protective effect of 16,16-dimethyl prostaglandin E2 on isolated rat hepatocytes against complement-mediated immune attack.

16,16-Dimethyl prostaglandin E2 was examined for its ability to inhibit complement-mediated in vitro hepatocytolysis by an antigen-antibody reaction. In the presence of fresh rat serum as a source of complement, 5-min culture of isolated rat hepatocytes with a monoclonal antibody against a rat liver-specific membranous antigen resulted in a marked, significant elevation in lactate dehydrogenase leakage into the culture medium. However, with heat-inactivated rat serum, such a reaction did not occur, indicating that the hepatocytolysis induced by the antibody was attributable to the membrane damaging action of complement activated by an antigen-antibody reaction. Pretreatment of the hepatocyte with 16,16-dimethyl prostaglandin E2 significantly suppressed the cytolytic reaction induced by the antibody in a concentration-dependent manner. These results show that 16,16-dimethyl prostaglandin E2 is capable of protecting isolated rat hepatocytes against the membrane-damaging insult of activated complement.

16,16-Dimethylprostaglandin E2↗
PubMed1992

Effects of sodium iodate on the electroretinogram c-wave in the cat.

The c-wave of the vitreal electroretinogram decreased in amplitude and was replaced by a slow, polarity reversed potential following an i.v. infusion of sodium iodate, as first described by Noell. Intraretinal recordings showed that the negative-going c-wave, induced by iodate (30 mg/kg), was composed of reduced slow pIII and trans-epithelial c-wave. The effects of iodate on these components may originate from direct effects on the retinal pigment epithelial cells, namely, a large decrease in the trans-epithelial resistance. Other factors could have contributed to the change in the c-wave amplitude.

Animals↗
PubMed1992

Simple and accurate assay for tyrosine hydroxylase from bovine retina by high-performance liquid chromatography with fluorescence detection.

We present a simple and sensitive assay for tyrosine hydroxylase (TH) using high-performance liquid chromatography (HPLC) with a fluorescence detector which enabled us to study bovine retinal TH of a small quantity in crude retinal samples. The detection limit with this method was 1 pmol of dihydroxyphenylalanine (DOPA) enzymatically produced. Retinal TH exhibited the maximum activity at pH 6 to 6.3, and almost none at physiological pH of above 7, a tendency similar to that reported for striatal TH.

Animals↗
PubMed1992

Intravitreal neovascular tissue of proliferative diabetic retinopathy: an immunohistochemical study.

Intravitreal neovascular tissue in 8 cases of proliferative diabetic retinopathy was investigated using immunohistochemical techniques. All 8 cases yielded positive immunoreactivity for type II collagen (vitreous collagen). The intravitreal neovascular tissue was classified into two groups (A or B), depending upon the distribution of type II collagen. In group A (3 cases), blood vessels were entirely surrounded by vitreous collagen, and in group B (5 cases), the vessels proliferated on one side of a mass of vitreous collagen. Type I and III collagens were distributed diffusely within the extracellular space of the tissue, whereas type IV collagen and fibronectin (FN) formed a basement membrane-like foundation for the newly formed vessels. Glial fibrillary acidic protein (GFAP)-immunoreactive cells were not clearly detected in any of the cases. Neovascular tissue typically proliferated on the posterior vitreous surface (as found in group B), but was also found to penetrate the vitreous gel (as found in group A). As neovascular tissue proliferation proceeded, types I, III and IV collagens and FN were produced. Glial cells (GFAP-positive cells) were not essential for neovascular tissue formation.

Animals↗
PubMed1992

Mass cultivation of human retinal pigment epithelial cells with microcarrier.

Microcarrier cell culture permits mass cultivation of anchorage-dependent cells. In this study, mass cultivation of human retinal pigment epithelial (RPE) cells was studied using Cytodex 3 (Pharmacia) as a microcarrier. Human RPE cells were established from aborted fetuses and cultured in Dulbecco's modified Eagle's Medium (DMEM). After the 3rd-5th passages, RPE cells were suspended in 50 ml of DMEM in a spinner flask at a density of 2 x 10(5)/ml, and Cytodex 3 was added to the spinner flask at a bead density of 10 mg/ml. Cultures were maintained at 20-50 rpm (final speed) on a magnetic stirrer, and DMEM was added up to 100 ml. Fifty milliliters of DMEM were decanted and replaced with fresh DMEM every 2 days. After 1 week, a cell density of 10(6)/ml DMEM was obtained. Phase contrast microscopy showed bridging formation between microcarriers, which suggests tight cell adhesion. Microcarrier cell culture has a variety of advantages which include greater cell production, use of less medium and less risk of contamination compared to the conventional monolayer culture technique, and it also allows passaging without using proteases. Using this culture system, greater possibilities for wider application of new cell cultures can be expected.

Cell Count↗
PubMed1992

Dependence of biphasic heart rate response to sustained hypoxia on magnitude of ventilation in man.

We studied the dynamic profile of respiratory and circulatory activities during sustained isocapnic hypoxia in healthy males. In response to end-tidal PO2 depression to about 55 Torr, minute ventilation first increased briskly and then depressed. Such biphasic response to hypoxia was also observed in the heart rate. A significantly positive correlation was found between the magnitudes of ventilatory and heart rate responses. No significant increases were found in arterial noradrenaline and potassium, but adrenaline significantly increased gradually with time. Furthermore, when VT and f were intentionally maintained constant so as to prevent the biphasic ventilatory change, the biphasic heart rate response previously seen in spontaneous hypoxic breathing disappeared. We suggest that the heart rate is mainly determined by the pulmonary vagal inflation reflex. Putative neurochemicals to elicit hypoxic ventilatory depression, and arterial catecholamine and potassium concentrations may not be directly related to the specific profile of the biphasic heart rate response during moderate hypoxia.

Adult↗
PubMed1992

Growth factor-dependent phosphorylation of membrane proteins in cultured human retinal pigment epithelial cells.

Recently, growth factors are known to phosphorylate tyrosine residues of proteins to regulate cellular functions. We investigated growth factor-dependent phosphorylation of membrane proteins in cultured human retinal pigment epithelial (RPE) cells. The phosphorylation experiments were done in membrane preparations of cultured RPE cell and the reaction was started by applying [32P]adenosine 5'-triphosphate (ATP) at 0 degrees C, and terminated after 0, 1, 5, 15, and 30 min. The samples were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and were analyzed by autoradiography. Many proteins showed time-dependent phosphorylation. Among them, a 170 kDa protein showed platelet-derived growth factor (PDGF)-specific phosphorylation with both time- (up to 30 min) and dose-(maximal effect at 50 ng/ml) dependence. On the other hand, epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) showed no specific phosphorylation. Phosphoaminoacids of the 170 kDa protein were analyzed by thin layer chromatography and autoradiography. Phosphotyrosine showed much higher radioactivity than phosphoserine or phosphothreonine. Consequently, PDGF induced phosphorylation of the 170 kDa protein which mainly consisted of phosphotyrosine. The data suggest that tyrosine phosphorylation of membrane protein is involved in signal transduction of PDGF in human RPE cells.

Adenosine Triphosphate↗
PubMed1992

[Hypoxic ventilatory response and hypoxic depression].

We investigated whether or not the adaptation of peripheral chemoreceptor (PCR) activity can contribute to hypoxic ventilatory depression (HVD) during sustained hypoxia for 20 min in both healthy subjects and patients with sleep apnea. Effects of HVD on diaphragm (DIA) and genioglossal muscle (GG) were also assessed. Withdrawal test, which is well established to solely represent the function of PCR, was repeatedly conducted at 5 and 20 min during sustained hypoxic condition. The results suggested that PCR did not play an important role in the development of HVD. When HVD ensued during sustained hypoxia, minute ventilation and EMGDIA were suppressed to the same extent in both groups. On the other hand, EMGGG was strongly and consistently attenuated in OSAS, whereas it was not always the case in healthy subjects. We speculate that treatment for hypoxic conditions can induce improvement of impaired regulation of breathing via central mechanisms, and it can be an important factor reducing the incidence and the severity of upper airway occlusion or collapse.

Adult↗
PubMed1992

[Clinical and echocardiographic evaluation of the effects of atrial defibrillation in patients with idiopathic cardiomyopathy].

To elucidate the effects of atrial defibrillation in patients with idiopathic cardiomyopathy, we clinically and echocardiographically assessed 6 patients with hypertrophic cardiomyopathy (HCM) and 7 patients with dilated cardiomyopathy (DCM). Their mean age was 57 +/- 14 years and the mean duration of their atrial fibrillation (Af) was 47 +/- 29 days. There were no differences in age and the duration of Af between the HCM and DCM groups. We assessed the effects of defibrillation on the NYHA functional classification, heart rate (HR), systolic blood pressure (S-BP), M-mode echocardiographic data (LVDd, LVDs, %FS, LAD) and transmitral pulsed Doppler echocardiographic findings (peak velocity, time-velocity integral of rapid and atrial filling waves). These indices were obtained before and 52 +/- 22 days after defibrillation, and were compared with each other. 1. HR decreased (HCM: 87 +/- 16-->58 +/- 7/min, DCM: 93 +/- 19-->70 +/- 14/min) and total left ventricular filling increased (HCM: 6 +/- 1-->11 +/- 4 cm, DCM: 6 +/- 1-->10 +/- 2 cm) after defibrillation, and the increment of %FS (HCM: 36 +/- 6-->41 +/- 6%, DCM: 16 +/- 6-->25 +/- 11%) was observed. Four of 6 HCM patients and 5 of 7 DCM patients also improved with regard to the NYHA classification. 2. After defibrillation, LVDd increased in HCM (42 +/- 4-->47 +/- 4 mm), but not in DCM. However, LVDs decreased in DCM (52 +/- 9-->44 +/- 12 mm), but not in HCM. We concluded that atrial defibrillation had a beneficial effect on the recovery of the left ventricular function both in HCM and DCM due to the reduction in HR and increase in left ventricular filling. The mode of LV functional improvement after defibrillation varied depending on the state of patient's basal pathophysiology .

Adult↗
PubMed1992

Cytochemistry of protein kinase C and Na-K-ATPase in rabbit ciliary processes treated with phorbol ester.

Immunocytochemical localization of protein kinase C (PKC) in rabbit ciliary processes was investigated using anti-PKC monoclonal antibodies (MAbs) against rabbit Types 1, 2, and 3 PKC. Specific immunolabeling was observed in nonpigmented epithelial (NPE) cells and in the capillaries of the ciliary processes with anti-Types 2 and 3 MAbs. No apparent staining was seen with anti-Type 1 MAbs. Immunoelectron microscopy of Types 2 and 3 MAbs revealed a diffuse distribution of immunoreactive PKC in the cytoplasm, in the nucleus, and on the plasma membrane in the NPE cells. When incubated with phorbol 12-myristate 13-acetate (PMA), the distribution of PKC was basically similar to that of the untreated group. However, the labelling density on the plasma membrane at basolateral interdigitation increased considerably for anti-Types 2 and 3 PKC MAbs. In addition, the enzyme cytochemical activity of Na-K-ATPase (ouabain-sensitive K-NPPase) and its change after PMA administration in the ciliary processes were observed. An intense reaction was seen on the basolateral plasma membrane of the NPE cells. In the PMA-treated group, the enzyme activity of Na-K-ATPase apparently was decreased. These findings provide evidence that PKC plays a crucial role in the function of the NPE cells of the ciliary processes, possibly in aqueous humor production.

4-Nitrophenylphosphatase↗
PubMed1992

Ca2+ mobilization in nontransformed ciliary nonpigmented epithelial cells.

To investigate the calcium second messenger system in nonpigmented epithelial (NPE) cells, we studied drug-dependent cytosolic free Ca2+ concentration ([Ca2+]i) transients in cultured nontransformed human and rabbit NPE cells with a fluorescent Ca2+ indicator, fura-2, and a digital video-imaging system. The main findings of this study were: (1) The basal [Ca2+]i was 141.9 +/- 1.2 nM (mean +/- standard error of the mean, n = 401) in humans and 157.0 +/- 1.4 nM (mean +/- SEM, n = 346) in rabbits. (2) Isoproterenol (10(-4) M) had little effect on [Ca2+]i mobilization in both species. Norepinephrine (10(-4) M) and epinephrine (10(-4) M) increased [Ca2+]i in 56% and 78% of rabbit NPE cells by 1.8- and 2.1-fold of basal [Ca2+]i, respectively, but induced little [Ca2+]i change in human NPE cells. Carbachol (10(-3) M) elicited significant [Ca2+]i increase (more than 3-4-fold of basal level) in about 60-70% of NPE cells in both species. Heterogeneity was seen in the cellular response to these agonists. (3) Norepinephrine-induced response was blocked by phentolamine (10(-5) M), and the effect of carbachol was blocked by atropine (10(-4) M). (4) Time course of norepinephrine-induced [Ca2+]i change was primarily monophasic. In contrast, [Ca2+]i transients induced by carbachol were mostly biphasic. (5) The duration of carbachol- or norepinephrine-induced responses were shortened by the chelation of extracellular Ca2+ without affecting other parameters of the reaction. This study confirms the presence of the calcium signaling system in cultured nontransformed human and rabbit NPE cells.

Adrenergic alpha-Antagonists↗