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Biomedical subjects

N Hirai

Publications and source records attributed to N Hirai.

At least 91 records · Page 5Linked to original sources
PubMed1990

Activity of crossed spinocerebellar tract neurones in the thoracic spinal cord in relation to the central respiratory rhythm.

Correlation between respiratory movement and neural discharges of antidromically identified 20 crossed spinocerebellar tract (SCT) neurones in the T8-11 segments was examined in the anaesthetized, paralysed cat. Activity of 11 neurones of them was related to phrenic nerve activity; 7 neurones increased and 4 decreased their activity during the active phase of the phrenic nerve. Their rhythmic activity remained even after artificial ventilation was turned off, indicating the central genesis of their rhythmic activity. By comparing discharge patterns with the ventilator on and off, it is suggested that half of these crossed SCT neurones appear to receive additional inputs from the periphery. Neurones which increased their firing rate during phrenic nerve activity tend to respond with decrease discharge to passive chest inflation, and vise versa.

Animals↗
PubMed1988

Activity of dorsal spinocerebellar tract neurones in the thoracic spinal cord in relation to respiratory movement.

The discharges of 22 antidromically identified dorsal spinocerebellar tract (DSCT) neurones, whose activity was modulated in phase with the spontaneous respiratory cycle, were recorded in the lower thoracic segments of anaesthetized cats. Out of them, 16 neurones increased in their firing rate during the inspiratory phase and 6 during the expiratory phase. When the animal was paralysed and artificially ventilated, rhythmic activity of DSCT neurones was locked to the respiratory pump cycle. Once the artificial ventilation was stopped, no modulation was found even though rhythmic activity of the phrenic nerve discharges still remained. The same results were obtained in vagotomized cats. These results indicate that some thoracic DSCT neurones convey information of peripheral events in the chest wall during respiratory movement.

Action Potentials↗
PubMed1988

Plasma levels of atrial natriuretic peptide during normal pregnancy and in pregnancy complicated by hypertension.

To clarify a possible role for atrial natriuretic peptide in the pathophysiology of pregnancy complicated by hypertension, we studied plasma levels of atrial natriuretic peptide in 176 pregnant women with or without hypertension. Plasma atrial natriuretic peptide levels in normal pregnant women showed a gradual increase as pregnancy advanced, but the mean (+/- SD) concentrations in women in each trimester (34.8 +/- 14.7 pg/ml in the first trimester, n = 35; 38.7 +/- 12.2 pg/ml in the second trimester, n = 34; and 43.1 +/- 20.0 pg/ml in the third trimester, n = 71) did not differ statistically from the mean plasma atrial natriuretic peptide level in nonpregnant women (38.2 +/- 13.6 pg/ml, n = 44). In contrast, plasma atrial natriuretic peptide levels were elevated in 9 of the 12 women who had hypertension. The mean plasma atrial natriuretic peptide concentration in these patients (162 +/- 95.2 pg/ml) was significantly (p less than 0.01) higher than in normal pregnant women and in nonpregnant controls. On the other hand, 11 pregnant women with proteinuria or edema but without hypertension had normal plasma atrial natriuretic peptide levels. These results suggest that plasma atrial natriuretic peptide levels are normal in women during uncomplicated pregnancy, while the levels are elevated in pregnancy complicated by hypertension. Increased atrial natriuretic peptide secretion in the latter condition may reflect a mechanism of compensation that operates in response to water and sodium retention.

Adult↗
PubMed1988

Effect of cisternal drainage after early operation for ruptured intracranial aneurysms.

The effect of postoperative cisternal drainage was assessed in 132 patients who underwent early surgery for ruptured aneurysms. Although the incidence of both cerebral vasospasm and mortality was low in the patients who had cisternal drainage, the incidence of hydrocephalus was significantly higher in these patients. Drainage has been recommended as a useful procedure because it has been shown to improve the prognosis through prophylaxis and relief of vasospasm and removal of blood-contaminated cerebrospinal fluid. However, the results of this study indicate that extensive cerebrospinal fluid drainage may lead to hydrocephalus, which can be controlled by regulation of the drainage outflow and pressure.

Cerebrospinal Fluid Shunts↗
PubMed1988

Comparison of fluorescence characteristics of products of peroxidation of membrane phospholipids with those of products derived from reaction of malonaldehyde with glycine as a model of lipofuscin fluorescent substances.

The fluorescence characteristics of product (I), formed during the lipid peroxidation of rat liver phosphatidylcholine liposomes containing glycine, and fluorescent product (II), derived from the reaction of malonaldehyde with glycine, were examined to elucidate the mechanism of fluorescent chromophore formation. Fluorescent product (I) had a fluorescence emission maximum at 430 nm when excited at 360 nm; its fluorescence intensity decreases in alkaline medium, but is restored by readjustment of pH to neutrality. In contrast, fluorescent product (II) exhibited an emission maximum at 458 nm, and the fluorescence was quenched at acidic pH. The fluorescent substances formed during the lipid peroxidation of hemoglobin-free human erythrocyte ghost membranes had similar fluorescence characteristics to product (I). Gel filtration experiments showed that molecular size of fluorescent product (I) was larger than that of fluorescent product (II). The thiobarbituric acid-reactive substances released from peroxidizing liposomal phospholipids had a larger molecular size than malonaldehyde, and produced little or no fluorescence with glycine. It is concluded that the precursor of the fluorescent product formed during the lipid peroxidation of membrane phospholipids differs from malonaldehyde. The mechanism of the formation of blue emitting fluorescent material, believed to be a component of lipofuscin, seems to involve peroxidized phospholipids of the membrane.

Animals↗
PubMed1988

Activities of the interferon system in patients with HBsAg-positive chronic hepatitis B during short-term steroid withdrawal therapy.

Changes in the host interferon system during short-term steroid hormone (prednisolone) withdrawal therapy in seven patients with HBeAg-positive chronic hepatitis B were investigated by estimating the in vitro interferon-alpha production in peripheral blood lymphocytes and 2-5 oligoadenylate synthetase activity in the serum. The interferon-alpha production induced by the Sendai virus and estimated in lymphocyte cultures was rapidly and significantly (p less than 0.01) reduced by prednisolone administration and subsequently followed by a recovery corresponding to its withdrawal. The serum 2-5 oligoadenylate synthetase activity showed a similar tendency to diminish under prednisolone administration and to revive during its withdrawal. In all four patients who developed an acute and transient post-prednisolone withdrawal exacerbation a significant initial increase in serum HBV-DNA levels was noted in accordance with the reduction in the host interferon system activity. The results suggest that the changes in the host interferon system activity, i.e. an initial fall and subsequent recovery as caused by a short-term steroid administration with gradual withdrawal, appear to promote viral replication in the early phase and the development of acute and transient exacerbation of hepatitis in the post-steroid withdrawal phase, which may lead to HBeAg/anti-HBe seroconversion in HBeAg-positive chronic hepatitis B patients.

2',5'-Oligoadenylate Synthetase↗
PubMed1987

Input-output relations of lobules I and II of the cerebellar anterior lobe vermis in connexion with neck and vestibulospinal reflexes in the cat.

In the anaesthetized cat, lobules I and II of the cerebellar anterior lobe vermis were examined to determine their role in the vestibulospinal and neck-vestibulospinal reflexes with respect to: the somatotopic representation of afferent inputs from labyrinth, neck and tail; and the inhibitory influence on vestibulospinal tract (VST) neurones receiving vestibular and neck afferent inputs. After electrical stimulation of the vestibular nerve and of neck afferents, almost identical responses via mossy fibres were evoked in the lobules, with the prominent response in lobules I and IIa of Larsell. Stimulation of the nerve supplying the dorsal region of the tail induced primarily the mossy fibre response, but also the climbing fibre response, in lobule II. The most responsive areas to tail and neck afferent stimulation did not overlap each other. In the lateral vestibular nucleus, 163 antidromically identified VST neurones were recorded extra- or intracellularly. On the basis of the response pattern to contralateral neck afferent stimulation, they were classified into 3 groups: neurones with excitation (n = 45); neurones with inhibition (n = 71); and neurones with no modulation (n = 47). Stimulation of lobules I-IIa inhibited the activities of 44 VST neurones. Out of them, 41 neurones belonged to the first group. They made up 91% of the group. Twenty-nine of these neurones, i.e. neurones receiving excitatory inputs from the neck and inhibitory inputs from the lobules, received additional excitatory input from the labyrinth. Although lobules I-IIa may be regarded as neck area in the anterior lobe vermis from the viewpoint of sensory input, they did not exert inhibitory influence only exceptionally on vestibulocollic neurones, but predominantly on VST neurones sending their axons to lower thoracic or more caudal segments in the spinal cord. It is suggested from these results that lobules I-IIa have a close relationship with the neck reflex and/or interaction of neck and vestibulospinal reflexes being concerned with the postural adjustment of a rather wide area of the body.

Animals↗
PubMed1987

Antiproliferative assay of human leucocyte interferon.

An in vitro microtitration system of the antiproliferative effect of human leucocyte interferon (IFN-alpha(Le)) was investigated. The preliminary experiments suggested that the antiproliferative effect of IFN-alpha(Le) was increased by prolonging the incubation period, by reducing the target cell concentration, and might be prescribed by the total IFN amounts in the challenge medium. By employing a system consisted of 1.5 X 10(4) Daudi cells in 0.2 ml of medium containing IFN dilutions and an incubation period of 3 days at 37 degrees C, the antiproliferative effects of twenty-one lots of partially purified IFN-alpha(Le) (PIF-alpha(Le)) preparations were titrated. The interassay variations in the antiproliferative titers of three PIF-alpha(Le) established in the present system were found to be in the same range as those in the antiviral titers estimated by a standard macroplaque reduction assay. The each titration curve was parallel, and the antiproliferative titers, assessed by the reciprocals of the IFN dilutions which suppress the cell growth in 50%, were significantly (p less than 0.01) correlated to the antiviral international units of them.

Antiviral Agents↗
PubMed1987

[Thermal analysis on water components in brain tissue--quantitative determination of free and bound water fractions].

In the living system, tissue water is considered to be composed of both free and bound water. Bound water encompasses the structural water of the cell wall and of various biological substances of high molecular weight, such as proteins and polypeptides. The present study was designed to measure thermoanalytically free and bound water on a quantitative basis in fresh brain of rats using differential scanning calorimetry (DSC). Our intention was to determine the fraction of freezable water in tissue. Freezable water in a tissue represents the fraction of free water. In the present study, freezing was conducted at a constant rate of -10 degrees C/min from room temperature to -75 degrees C by a SSC/560 S (Seiko Electronics). The system allows for calculation of the amount of free water from the differential scanning calorimetry curve employing a coloric constant of 79.4 cal/mg. Aluminium oxide was used as calorimetric reference. The fraction of bound water was calculated by subtraction of the amount of free water from that of total tissue water. Water binding to solid tissue component was estimated from tissue dry weight and the bound water fraction. Mean water content of normal gray matter in adult Wistar rats was 76.9 +/- 1.4% (SD). 88.9% of total tissue water was free whereas 11.1 +/- 2.8% (SD) was bound. Bound water of brain parenchyma amounted to 0.44 +/- 0.12 mg/mg dry weight. As compared to other tissues such as cardiac muscle and liver, brain parenchyma obviously exceeded in free water content. The total water content of serum was 94.4 +/- 1.2%; 90.7 +/- 2.6% was free and 9.3 +/- 2.6% (SD) was bound.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Histological and ultrastructural examination of the intrahepatic biliary tree in primary sclerosing cholangitis.

Intrahepatic bile ducts were examined histologically and ultrastructurally in wedge-biopsied liver specimens from three patients with primary sclerosing cholangitis. Bile ducts with periductal concentric fibrosis, which is a characteristic finding in primary sclerosing cholangitis, revealed ultrastructurally finger-like projections or fine undulations of the basal free surfaces with markedly duplicated basal lamina. The lamina was collared by a layer of elongated fibroblasts and thickened bundles of collagen fibers outwards. These changes were consistently found in all sizes of ducts examined, and might be related to progressive periductal fibrosis. Serial section observations showed that some severely affected ducts actually disappeared when accompanying severe periductal fibrosis. It would therefore appear that progressive periductal fibrosis may interrupt fluid and nutrient exchange between the bile duct epithelia and peribiliary capillary plexus, followed by obliteration of the biliary lumina. Although the bile ducts showed segmentally periductal lymphocytic infiltration and, ultrastructurally, point contacts between infiltrating lymphocytes and biliary epithelial cells were observed occasionally, the exact role of infiltrating lymphocytes in the pathogenesis of primary sclerosing cholangitis remains unclear.

Adult↗
PubMed1986

Natural killer (NK) cell activity and its in vitro response to interferon-alpha(Le) in chronic liver diseases and hepatocellular carcinoma.

The natural killer (NK) cell activity of peripheral blood lymphocytes (PBL) in patients with various chronic liver diseases, and its in vitro response to human interferon-alpha(Le) were investigated using a 16-h 51-Cr releasing cytotoxicity assay against YAC-1 or RSa target cells. The NK cell activity was found to be higher in chronic active hepatitis (CAH) and liver cirrhosis (LC) patients without HCC, whereas it was slightly lower in LC patients with hepatocellular carcinoma (HCC), than in normal controls. By the addition of IFN-alpha(Le) in vitro, the NK cell activity was clearly and dose-dependently augmented, even in chronic liver diseases, as well as in normal controls. The magnitude of this augmentation by 10,000 IU/ml of IFN-alpha(Le) in the various chronic liver diseases was not significantly different from that in normal controls. The results suggested that the response of NK cells to IFN-alpha(Le) is not impaired even in chronic liver disease conditions, while the level of NK cell activity may vary according to the type of chronic liver disease and may decrease in patients with HCC.

Adult↗
PubMed1986

Atrial natriuretic peptide in umbilical cord blood: evidence for a circulating hormone in human fetus.

To determine whether atrial natriuretic peptide (ANP) is a circulating hormone in the human fetus, ANP levels in umbilical cord plasma obtained at the time of delivery in 10 normal infants were measured by RIA. Plasma ANP levels were consistently higher in paired umbilical cord arterial than in cord venous samples. The mean umbilical cord arterial plasma ANP concentration [283 +/- 56 (+/- SEM) pg/ml] was significantly higher than that in cord venous plasma (165 +/- 27 pg/ml) or maternal peripheral venous plasma (155 +/- 25 pg/ml). Analyses by reverse phase high performance liquid chromatography revealed that the elution pattern of plasma ANP in cord arterial blood and that in maternal venous blood were nearly identical and that the retention time of the main ANP peak coincided with that of alpha-human ANP. These results suggest that alpha-human ANP is a circulating hormone in the human fetus.

Atrial Natriuretic Factor↗