Biomedical subjects

N Sakai

Publications and source records attributed to N Sakai.

At least 19 recordsLinked to original sources

PubMed1992

Effects of the histamine H3 receptor ligands thioperamide and (R)-alpha-methylhistamine on histidine decarboxylase activity of mouse brain.

The effects of the histamine H3 receptor ligands thioperamide and (R)-alpha-methylhistamine on the histidine decarboxylase (HDC) activity and histamine content of mouse brain were examined. Thioperamide, a histamine H3 antagonist, significantly increased the HDC activity in the brain of ddY, W/Wv and ICR mice 2-6 hr after its intraperitoneal (i.p.) injection. On the other hand, (R)-alpha-methylhistamine, a histamine H3-receptor agonist, caused no significant change in the HDC activity. The whole brain histamine content of ddY mice decreased significantly to 60-70% of the control level 2-8 hr after injection of thioperamide (25 mg/kg, i.p.), but then increased to 90% of the control level 10 hr after the injection. These in vivo results showed that blockade of the presynaptic histamine H3-receptor, which causes release of presynaptic histamine, increased the HDC activity.

Animals↗

PubMed1992

Rainbow trout cytochrome P-450c17 (17 alpha-hydroxylase/17,20-lyase). cDNA cloning, enzymatic properties and temporal pattern of ovarian P-450c17 mRNA expression during oogenesis.

A cDNA clone encoding cytochrome P-450c17 (17 alpha-hydroxylase/17,20-lyase) was isolated from a rainbow trout ovarian follicle cDNA library. The cDNA contained an open reading frame of 1,542 nucleotides encoding a protein of 514 amino acid residues. The amino acid sequence of trout P-450c17 shows a much greater homology with chicken P-450c17 than with that of human, bovine and rat. The trout P-450c17 expressed in non-steroidogenic mammalian COS-1 cells showed both 17 alpha-hydroxylase and 17,20-lyase activities. The cDNA only hybridized to a single species of mRNA (2.4 kb) isolated from rainbow trout ovaries; the 2.4 kb transcripts were abundant in trout ovaries during the later stages of oogenesis.

Aldehyde-Lyases↗

PubMed1992

Proton nuclear magnetic resonance studies on water structure in peritumoral edematous brain tissue.

Spin-lattice relaxation times (T1) of water protons and cross-relaxation times (TIS) between irradiated protein and water protons were measured to study the water structure in peritumoral edematous brain tissue of rats. Despite small changes in T1, water, and electrolyte contents, TIS values of water protons were significantly reduced in peritumoral edematous brain tissue when compared to those of the controls. Results indicate that the water structure in brain tissues may become altered at an early stage of edemic formation without causing any significant changes in cellular hydration. TIS might serve as a sensitive parameter for studying the water structure in a variety of tissues, such as in edematous brain tissue.

Animals↗

PubMed1992

Proton NMR studies on ischemic rat brain tissue.

The spin-lattice relaxation time (T1) of water protons and the cross-relaxation time (TIS) between irradiated protein protons and observed water protons were measured in order to study water-macromolecular interactions in ischemic rat brain tissues. Tissues were obtained by bilateral common carotid artery occlusion from stroke-prone spontaneously hypertensive rats. Water, Na, and K contents were measured in ischemic brain tissue at the same time. Water and Na content increased while the TIS value and K content decreased following ischemic insults. The T1 value did not change until 180 min after ischemia had been induced. Changes in the TIS value occurred earlier than changes observed for the T1 value, water, and electrolyte contents. Results indicate that the value of TIS may be useful for detecting cerebral ischemia and that the physical structure of water-macromolecular interaction may be altered soon after ischemic onset in brain tissue.

Animals↗

PubMed1992

Proliferative assessment of craniopharyngioma and epidermoid by nucleolar organizer region staining.

The histologic distinction between craniopharyngioma and epidermoid is equivocal. Eight craniopharyngiomas and ten epidermoids (including three dermoids) as well as nine rat (Wistar) abdominal skins that acted as control were investigated by a silver colloid method for nucleolar organizer regions (Ag-NORs). The mean number of Ag-NORs in at least 200 cells of both basal (columnar) epithelial cells and suprabasal (prickle) cells was evaluated. It was found that the mean number of Ag-NORs in basal cells of epidermoid and rat skin was significantly greater than that in suprabasal cells (P < 0.001 in nine of ten epidermoids and in all rat skins). On the other hand, of eight craniopharyngiomas, the mean Ag-NOR number in basal cells was not significantly different from that in suprabasal cells in five cases, and, further, the former was significantly smaller than the latter in the other three cases (P < 0.01 in two and P < 0.05 in one). These findings suggest that a stepwise maturation of the epithelial cells like that in mammalian skin epidermis exists in epidermoids but not in craniopharyngiomas. In craniopharyngiomas, the maturation of the epithelial cells seems to be considerably limited or lost from the aspect of proliferative potential as assessed by Ag-NOR score, which indicates neoplastic growth of craniopharyngiomas. Ag-NOR staining may thus be a useful method to distinguish craniopharyngioma from epidermoid.

Animals↗

PubMed1992

Distribution of cellular carbohydrate moieties in human dysontogenetic brain tumors, especially in craniopharyngioma and epidermoid/dermoid.

Cellular carbohydrate moieties of 65 human dysonotogenetic brain tumors (craniopharyngioma, epidermoid/dermoid, Rathke cleft cyst, germinoma and non-germinomatous germ-cell tumors) and 60 common brain tumors (glioma, meningioma, neurinoma and pituitary adenoma) were investigated histochemically using sections from Ulex europaeus (UEA-1), Dolichos biflorus (DBA), peanut (PNA) and soybean (SBA), and with anti-blood group A and LewisY (LeyY) antibodies. In craniopharyngiomas and epidermoid/dermoids, it was found that PNA and SBA binding sites existed in suprabasal cells of the epithelium, and that antigen of either blood group A or H (demonstrable by UEA-1) existed in more differentiated epithelial cells compared to the results reported in normal human skin epidermis. Rathke cleft cysts were stained with PNA or SBA, and two out of three Rathke cleft cysts also expressed either H or A antigen. In addition, DBA binding sites, as well as LeY antigen, were frequently seen in craniopharyngiomas and Rathke cleft cysts, but they were entirely absent in the epithelium of epidermoid/dermoid. On the other hand, PNA and SBA reactivities was also found in common brain tumors, while blood group A, H and LeY antigens and DBA reactivity were almost absent in these tumors. These findings demonstrate that carbohydrate moieties such as those of blood group antigens reported to be found in human skin epidermis exist in a similar form in craniopharyngioma, epidermoid/dermoid and the Rathke cleft cyst. The identification of blood group A, H and LeY antigens and DBA reactivity in brain tumors seems to be considerably limited and specific.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigens, Neoplasm↗

PubMed1992

Intracranial cavernous angioma in the 1st year of life and a review of the literature.

Three cases of symptomatic cavernous angioma occurring in the 1st year of life are presented. All three patients were treated with radical extirpation. Postoperatively, two of them improved, but the third died due to cerebral herniation secondary to recurrence of bleeding of the lesion. The clinical characteristics of cavernous angioma in the 1st year of life are briefly discussed and a review of the literature presented, including 16 previous cases operated on directly.

Brain Neoplasms↗

PubMed1992

Dolichos biflorus agglutinin binding to intracranial germ-cell tumors: detection of embryonal components in germinomas.

Dolichos biflorus agglutinin (DBA) binding was examined in 32 cases of intracranial human germ-cell tumors. In embryonal carcinomas, intense DBA binding sites were found on the free surface and cytoplasm of embryonal cells. In teratomas, glandular structures often had positive DBA binding sites. Yolk sac carcinomas and choriocarcinomas showed negative DBA affinity. Of 19 cases of germinomas, 10 showed no DBA-positive cells, while sporadically and/or collectively distributed-DBA positive cells were found in the other 9 cases. Common brain tumors such as gliomas, neurinomas and meningiomas were negative for DBA staining. Considering the cellular carbohydrate structure, these findings suggest that DBA-positive cells in germinoma might be evidence of differentiation into embryonal or some somatic components. In addition, because of the absence of DBA binding sites in the common brain tumors, the identification of such binding sites in brain tumors might act as a marker for embryonal or somatic components, especially among germ-cell tumors.

Alkaline Phosphatase↗

PubMed1992

Low-density lipoproteins in hyperalphalipoproteinemic heavy alcohol drinkers have reduced affinity for the low-density lipoprotein receptor.

Heavy alcohol intake causes a marked inhibition of cholesteryl ester transfer protein (CETP) activity resulting in cholesterol ester enrichment of HDL. In this study we have characterized LDL of 35 chronic heavy alcohol drinkers with hyperalphalipoproteinemia to clarify the effect of alcohol on the metabolism of LDL. Serum concentrations of LDL-cholesterol and apolipoprotein B were normal, while the chemical composition of LDL was characterized by depletion of cholesteryl ester and enrichment of triglyceride. The LDL particles of the drinkers were significantly smaller in size than those of controls and had reduced affinity for LDL receptors of normal human fibroblasts. After cessation of alcohol, these abnormal characteristics returned toward normal along with elevation of CETP activity. These results suggest that heavy alcohol intake alters the compositions and particle size of LDL, consequently reducing their affinity for LDL receptors. This may be attributed, at least in part, to the reduction of CETP activity.

Adult↗

PubMed1992

Isolation and characterization of goldfish cdk2, a cognate variant of the cell cycle regulator cdc2.

This paper reports the nucleotide and predicted amino acid sequences of the goldfish cdk2, a cognate variant of the cell cycle regulator cdc2. The predicted protein sequence shows strong homology to the other known cdk2 (88% for Xenopus and 90% for human). A monoclonal antibody against the C-terminal sequence of goldfish cdk2 recognized a 34-kDa protein in extracts from various goldfish tissues. The protein level was high in such tissues as testis and ovary containing actively dividing cells. Protein cdk2 binds to p13sucl, the fission yeast suc1+ gene product, but not to cyclin B, with which cdc2 forms a complex. The kinase activity of cdk2 increased 30-fold when oocytes matured, although its protein level did not remarkably change. Anti-cdk2 immunoprecipitates from 32P-labeled mature oocyte extracts contained a 47-kDa protein, which was not recognized by either anti-cyclin A or anti-cyclin B antibody, indicating complex formation of cdk2 with a protein other than cyclins A or B.

Amino Acid Sequence↗

PubMed1992

Effects of (S)-alpha -fluoromethylhistidine and metoprine on locomotor activity and brain histamine content in mice.

We examined the effects of (S)-alpha -fluoromethylhistidine (FMH), an inhibitor of histidine decarboxylase, and metoprine, an inhibitor of histamine N-methyltransferase, on the locomotor activity and the brain histamine content of ICR mice. The brain histamine content was decreased by FMH (12.5 or 50 mg/kg, i.p.) and increased by metoprine (4 mg/kg, i.p.). Under these conditions, the locomotor activity and the number of rearing were significantly decreased and increased by FMH and metoprine, respectively. The higher the brain histamine content, the greater the locomotor activity and vice versa. In a previous paper [Sakai et al., Life Sciences, 48, 2397-2404 (1991)], we showed that thioperamide, a histamine H3 antagonist, which enhances the release of histamine from histaminergic neurons, in doses of 12.5 and 25 mg/kg, i.p. increases the locomotor activity, whereas it decreases the brain histamine content. Taken together, these results support the hypothesis that central histaminergic neurons may be involved in the control of state of locomotion and rearing.

Animals↗

PubMed1992

Polydisperse low-density lipoproteins in hyperalphalipoproteinemic chronic alcohol drinkers in association with marked reduction of cholesteryl ester transfer protein activity.

Long-term heavy alcohol intake is well known to increase serum high-density lipoprotein (HDL) cholesterol concentrations. Epidemiologic studies have shown that the protective effect of alcohol intake against coronary heart disease (CHD) is observed in moderate alcohol drinkers, but not in heavy ones. To clarify whether heavy alcohol intake may cause abnormalities in lipoprotein metabolism, we analyzed the plasma lipoproteins in eight male chronic heavy alcohol drinkers with marked hyperalphalipoproteinemia. Although their serum HDL cholesterol levels were remarkably high, ranging from 2.67 to 3.58 mmol/L, three patients had CHD and corneal arcus was present in seven patients. Cholesteryl ester transfer protein (CETP) activity was reduced in all subjects (7.3% +/- 4.2%/10 microL/18 h in alcohol drinkers v 20.5% +/- 2.4%/10 microL/18 h in control; mean +/- SD, P < .001). The CETP mass levels were also markedly reduced in these subjects. The analysis of low-density lipoprotein (LDL) on nondenaturing polyacrylamide gradient gel electrophoresis revealed that four subjects with severely low CETP activity (< 25% of control) had polydisperse LDLs, similar to those observed in genetic CETP deficiency. The other four subjects with approximately half the normal CETP activity had homogeneous but smaller-sized LDLs, as compared with control subjects. Particle size of HDL was larger than that of normal control HDL in all subjects. After cessation of alcohol intake, plasma HDL cholesterol levels were decreased and LDLs became more homogeneous and normal in size, in parallel with elevation of CETP activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Phase differences between chest and mouth flows in patients suffering from pulmonary disease.

The phase difference (PD) between mouth flow and chest flow during rest breathing was measured in pulmonary diseased patients using a body box and the results were compared with normal subjects. Whereas the PD increased in patients with chronic pulmonary obstructive disease (COPD) compared to normal subjects, PD was found to be normal in patients with interstitial pulmonary fibrosis (IPF) (Normal: 2.94 +/- 1.25, COPD: 11.32 +/- 4.17*, IPF: 2.62 +/- 1.67 degrees; *P < 0.01). PD correlated well with FEV1.0/VC%, PFR, RV/TLC, VTG and Ra (r: -0.759, -0.672, -0.788, 0.666, 0.606). From an in-depth analysis of the results, we suggest that the factors which increase PD in COPD patients include hyperinflation of the lung, increases in airway resistance and increases in the parallel inhomogeneity of airway resistance accompanied by an unevenness of alveolar pressures. PD was thought to be clinically useful for the evaluation of the pathological stages of COPD because it reflects the overall clinical manifestations in COPD patients.

Adult↗

PubMed1992

Central neurocytoma presenting with gigantism: case report.

We report a case of central neurocytoma presenting with gigantism. The patient was a 19-year-old man with a 2-year history of rapid growth. Computed tomography revealed a round, slightly enhancing calcified tumor in the septal region. This lesion was resected, and postoperative radiotherapy was given. The preoperative serum growth hormone level was 20.7 ng/mL, and postoperatively this fell to 0.9 ng/mL. Pituitary dysfunction was not noted either before or after the operation. A low level of production of growth hormone releasing factor was detected when tumor cells obtained during surgery were cultured.

Adult↗

PubMed1992

Thromboxane A2 mimetic U46619 stimulates ciliary motility of rabbit tracheal epithelial cells.

To elucidate whether thromboxane A2 (TxA2), one of the important arachidonic acid metabolites that may play a role in the development of airway inflammation, affects respiratory ciliary motility and, if so, what the mechanism of action is, we measured ciliary beat frequency (CBF) of rabbit cultured tracheal epithelium in response to U46619, a TxA2 mimetic agonist, by a photoelectric method. Addition of U46619 (10(-5) M) increased CBF from 17.7 +/- 0.7 to 22.8 +/- 1.4 Hz (mean +/- SE, p less than 0.01) within 5 min, which was followed by a decline to the baseline value by 10 min. This effect was concentration-dependent, the maximal increase from the baseline value and the drug concentration required to produce a half-maximal effect (EC50) being 26.9 +/- 4.6% (p less than 0.01) and 3 x 10(-7) M, respectively. The U46619-induced increase in CBF was abolished by SQ29548, and TxA2 receptor antagonist, and inhibited by verapamil, a Ca(2+)-entry blocker, and H-7, a protein kinase C inhibitor. These results suggest that TxA2 stimulates ciliary motility through the activation of airway epithelial TxA2 receptors, and that this effect may be exerted from Ca(2+)-influx and protein kinase C.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1992

Double 20q- anomaly in myelodysplastic syndrome.

Two patients with myelodysplastic syndrome (MDS) whose bone marrow (BM) cells contained duplicate 20q- chromosomes are reported. No particular differences between the hematologic findings of four patients with single 20q- and the two patients with double 20q- chromosomes were noted. No differences in breakpoints on the 20q- chromosome were noted in these six patients, and the breakpoint was identified as 20q11. The presence of double 20q- chromosomes in MDS patients suggests, however, that the deleted chromosome has oncogenic activity.

Aged↗

PubMed1992

Modulation of cell-to-cell coupling between myometrial cells of the human uterus during pregnancy.

OBJECTIVE: The purpose of this study was to investigate changes in cell-to-cell coupling of human myometrium during pregnancy to assess the presence and permeability of gap junctions. STUDY DESIGN: To evaluate the coupling, input resistance was measured and intercellular spread of Lucifer yellow was observed with microelectrode techniques in intact myometrial preparations from four nonpregnant women, 13 women not in labor, and three women in labor. Octanol, isoproterenol, and dibutyryl adenosine 3',5'-cyclic monophosphate were applied to the preparations to assess their effects on cell-to-cell coupling. RESULTS: Input resistance of myometrial cells was decreased (p less than 0.001) and intercellular spread of Lucifer yellow was increased during pregnancy. Octanol, isoproterenol, and dibutyryl adenosine 3',5'-cyclic monophosphate rapidly and reversibly increased input resistance (p less than 0.001 for all these agents) and blocked Lucifer yellow spread in tissues from pregnant patients. CONCLUSIONS: Cell-to-cell coupling between human myometrial cells is spontaneously improved during pregnancy because of the presence of gap junctions. The coupling is rapidly and reversibly decreased by octanol, isoproterenol, and dibutyryl adenosine 3',5'-cyclic monophosphate as a result of decreased permeability of gap junctions. These two methods of modulation of gap junctions are suggested to be major mechanisms for control of myometrial contractile activity in the human uterus during pregnancy.

1-Octanol↗

PubMed1992

Studies of connexin 43 and cell-to-cell coupling in cultured human uterine smooth muscle.

OBJECTIVE: The aim of this study was to assess the presence and the permeability of gap junctions between human uterine smooth-muscle cells in culture. STUDY DESIGN: The uterine smooth muscles obtained from term-pregnant women were cultured. The presence of gap junction was evaluated by immunocytochemistry with gap junction protein antibodies and by measuring input resistance and intercellular spread of lucifer yellow. These measures also evaluated the permeability of gap junctions. Octanol, isoproterenol, dibutyryl cyclic adenosine monophosphate and forskolin were applied to the cultures to assess their effects on the permeability of gap junctions. RESULTS: During culture, immunocytochemical staining of gap junction protein (connexin 43) was increased and input resistance was decreased on day 2 of culture versus day 21 (18.4 +/- 7.87 M omega day 2; 3.8 +/- 1.76 M omega, day 21; p < 0.001). However, the decrease in input resistance was related to cell density rather than time in culture (16.4 +/- 5.01 M omega, single cells on days 1 and 2; 5.3 +/- 2.35 M omega, high-density cultures on days 1 and 2; p < 0.001). Octanol increased input resistance and intercellular spread of lucifer yellow in confluent cultures; isoproterenol, dibutyryl cyclic adenosine monophosphate, and forskolin did not. CONCLUSIONS: The increased staining of connexin 43 and the decreased input resistance during culture are evidence of elevated number of gap junctions between cells. The rapid and reversible increase in input resistance and decrease in spread of lucifer yellow by octanol are the result of decreased permeability of gap junctions. These two methods of modulation of gap junctions in human uterine smooth muscles are thought to be major mechanisms for the control of uterine contractility.

Cell Communication↗