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M Nishikawa

Publications and source records attributed to M Nishikawa.

At least 235 records · Page 13Linked to original sources
PubMed1998

Three classes of GABA-like immunoreactive neurons in the mushroom body of the cockroach.

The mushroom body (MB) is a higher center of the insect brain and is critical to some forms of associative memory. Each MB consists of calyces connected to alpha and beta lobes via pedunculus. In the calyces, input neurons make synaptic connections with intrinsic neurons. In the pedunculus and lobes, intrinsic neurons make synaptic connections with output neurons. Here, the distribution of gamma-aminobutyric acid (GABA)-like immunoreactivity in the MB of the cockroach Periplaneta americana was investigated, using an antiserum against a GABA-protein conjugate, to elucidate inhibitory pathways of the MB. We report that three classes of extrinsic neurons of the MB exhibit GABA-like immunoreactivity. The first is four large neurons which arborize in a diffuse neuropil surrounding the alpha lobe and project into whole areas of the calyces. Their cell bodies are 30-50 micron in diameter, among the largest in the brain. The second group is 7-9 neurons ascending from the circumesophageal connective and projecting into the calyces, which probably represent inhibitory input neurons. The third group is ca. 40 neurons with dendritic arborizations in the junction between the pedunculus and the lobes, which probably represent inhibitory output neurons.

Animals↗
PubMed1998

Function-specific distribution patterns of axon terminals of input neurons in the calyces of the mushroom body of the cockroach, Periplaneta americana.

Input neurons (INs) in the calyces of the mushroom bodies (MBs) of the cockroach brain were examined by single- or multiple-staining with cobalt lysine and by Golgi impregnation. Olfactory INs had axon terminals with tuft-like, button-like or spiny-blebbed arbors in specific concentric zones in calycal neuropil. INs which responded to light stimulation had thick brush-like arbors along with axonal branches extending radially along the inner layer of calycal neuropil. Some of multiglomerular INs and two types of protocerebral INs extended blebbed axonal branches to the outer surface layer of calycal neuropil or thick bush-like axonal branches with many varicosities to entire calycal neuropil. The distribution patterns of dendrites and axon terminals of INs in the calyces suggest the existence of functional subdivisions in calycal neuropil.

Animals↗
PubMed1998

Inhibitory effect of 1alpha-hydroxyvitamin D3 on N-methyl-N'-nitro-N-nitrosoguanidine-induced gastrointestinal carcinogenesis in Wistar rats.

The effect of 1alpha-hydroxyvitamin D3 (1alpha(OH)D3) on gastrointestinal carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was investigated in male Wistar rats. After oral treatment with 0.01% MNNG for 24 weeks, rats were given 0.04 microg of 1alpha(OH)D3 or its vehicle by gastric intubation three times a week for 24 weeks. The incidence of gastrointestinal tumors was 16/30 (53%) in rats treated with MNNG alone, 16/30 (53%) in those treated with MNNG plus vehicle and 8/30 (27%, P < 0.05) in those treated with MNNG plus 1alpha(OH)D3. The number of tumors per rat in the group treated with MNNG plus 1alpha(OH)D3 was half those in the control groups (P < 0.05). Results indicated that a non-hypercalcemic dose of 1alpha(OH)D3 had an inhibitory effect on MNNG-induced duodeno-intestinal carcinogenesis.

Animals↗
PubMed1998

Pharmacokinetic analysis of hepatic uptake of galactosylated bovine serum albumin in a perfused rat liver.

Hepatic uptake of 111In-labelled galactosylated bovine serum albumin (Gal-BSA) with different number of galactose residues per BSA were studied in rat liver perfusion experiments. During a single-pass constant infusion mode, [111In]Gal-BSAs (0.1-2.0 micrograms/ml) were continuously extracted by the liver and its extraction ratio at steady-state (Ess) was lowered as the inflow concentration increased. Hepatic clearance of [111In]Gal-BSAs increased significantly according to the increase in the number of galactose residues per BSA at an inflow concentration of 0.7 micrograms/ml. The outflow patterns of [111In]Gal-BSAs at various inflow concentrations were simultaneously fitted to a one-organ pharmacokinetic model, by which we can characterize their binding to the cell surface and internalization processes separately. The parameters obtained were varied significantly among [111In]Gal-BSAs depending on the number of galactose residues and indicate that not only the binding to the receptors but also the internalization after the binding are regulated by the number of galactose residues per BSA during hepatic uptake.

Animals↗
PubMed1998

Poor outcome in disseminated intravascular coagulation or thrombotic thrombocytopenic purpura patients with severe vascular endothelial cell injuries.

Various hemostatic and vascular endothelial cell markers were measured in patients with disseminated intravascular coagulation (DIC), non-DIC, or thrombotic thrombocytopenic purpura (TTP) and in healthy volunteers to examine the relationships between the hemostatic abnormalities or vascular endothelial cell injuries and the patients' outcomes. Although the plasma levels of soluble fibrin monomer, thrombin-antithrombin complex, plasmin-plasmin inhibitor complex, and D-dimer were significantly increased in the DIC patients, there were no significant differences in these markers between the DIC patients who survived and those who died, suggesting that these markers might not be directly related to the patient outcome. The plasma thrombomodulin (TM) levels in the DIC and TTP patients were significantly higher than those in the healthy volunteers, and the plasma TM levels in the patients who died were significantly higher than those in the patients who survived. These findings showed that the TM level reflected the outcome, and that the outcome of the diseases underlying DIC and TTP might depend on vascular endothelial cell injuries. The plasma protein C and antithrombin activities were markedly reduced in the DIC, non-DIC, and TTP patients who died compared to those who survived. These findings suggest that reduced plasma antithrombin and protein C activities are useful markers of systemic vascular endothelial injuries. Although the plasma tissue factor (TF) levels were significantly increased in the DIC patients, there was no significant difference in the plasma TF levels between the DIC patients who died and those who survived. In conclusion, we found that the outcome of the diseases underlying DIC and TTP is related to vascular endothelial cells, and that plasma TM, antithrombin, and protein C are useful markers for systemic vascular endothelial cell injury.

Antifibrinolytic Agents↗
PubMed1998

Role of glutathione in nitric oxide-dependent regulation of energy metabolism in rat hepatoma cells.

Previous studies in this laboratory revealed that nitric oxide (NO) reversibly inhibits the respiration of isolated mitochondria and ascites hepatoma (AH-130) cells by an oxygen concentration-dependent mechanism. The inhibitory effect of NO on the respiration of AH-130 cells was enhanced by treating with digitonin that selectively permeabilized plasma membranes and released cytosolic low-molecular-weight compounds. Reduced glutathione (GSH) is the most abundant cytosolic thiol that easily reacts with NO. To elucidate the mechanism by which digitonin enhanced the inhibitory action of NO, the effect of GSH and related thiols was studied with AH-130 cells and their mitochondria. The inhibitory effect of NO on the respiration of digitonin-treated cells was suppressed by either GSH, L-cysteine, or N-acetylcysteine, but not by oxidized glutathione. The inhibitory effect of NO on the respiration of their mitochondria was also decreased by GSH. In contrast, the inhibitory effect of NO was markedly enhanced with AH-130 cells obtained from animals that were pretreated with L-buthionine sulfoximine (BSO), a specific inhibitor for GSH synthesis. Kinetic analysis revealed that NO dose-dependently decreased GSH levels in AH-130 cells with concomitant generation of S-nitrosothiols. Although S-nitrosoglutathione (GSNO), a slow releaser of NO, also inhibited the respiration of tumor cell mitochondria, its effect was significantly lower than that of NO. These results suggest that cellular GSH might play pivotal roles in the regulation of energy metabolism in hepatoma cells by modulating free forms of NO.

Acetylcysteine↗
PubMed1998

Macrophage-derived nitric oxide induces apoptosis of rat hepatoma cells in vivo.

Although nitric oxide (NO) has been postulated to play important roles in host defense mechanisms against tumor cells, a direct evidence supporting this hypothesis is lacking. To obtain molecular insights into the antitumor action of NO, its metabolism and effect on ascites hepatoma (AH-130) cells were investigated in tumor-bearing rats. Kinetic analysis revealed that substantial amounts of nitrite and nitrate, metabolites of NO, appeared in plasma and ascites of AH-130-inoculated rats. Western blot analysis revealed that a large number of macrophages that expressed inducible type of NO synthase (iNOS) appeared in cancerous ascites, particularly during 1 to 2 weeks after inoculation of AH-130 cells. When NO generation by peritoneal macrophages increased, a significant fraction of AH-130 in ascites fluid underwent apoptosis as judged from the fragmentation of their nuclear DNA. Kinetic analysis revealed that NO strongly inhibited mitochondrial electron transport and changed calcium status in AH-130 cells, particularly under low oxygen tensions such as in cancerous ascites. Intraperitoneal injection of NO donor strongly enhanced DNA fragmentation of AH-130 cells. Antimycin A, a specific inhibitor for mitochondrial electron transport, also induced DNA fragmentation of AH-130 cells by a mechanism that was inhibited by adding ascorbate and tetramethyl-p-phenylene diamine (TMPD) as electron donors. These results indicate that NO derived from peritoneal macrophages inhibits mitochondrial electron transport and disturbs calcium homeostasis in ascites hepatoma AH-130 cells, thereby inducing their apoptosis in vivo.

Animals↗
PubMed1998

Clinical significance of ventricular size in shunted-hydrocephalic children.

For maintaining the intracranial buffering capacity against shunt obstruction, we tried to seek the most suitable size of the lateral ventricles in hydrocephalic children. Thirty-seven shunted-hydrocephalic children who required emergent revision of the shunt were analyzed. At the time of shunt obstruction, the lateral ventricle remained small (0.35 or less than 0.35 on the Evans' index) in 13 patients (Slit-like group), but it enlarged (more than 0.35 on the Evans' index) in 24 patients (Dilated group). The mean age in the Slit-like group was significantly older than in the Dilated group and there was no patient younger than 3 years in the Slit-like group. Compared with the Dilated group, the Slit-like group showed significantly rapid deterioration into lethargy after shunt obstruction. Also, at the time of obstruction CT scans showed a significantly higher rate of narrowing of the ambient cistern. While the shunt was working well before shunt obstruction, the Evans' index was less than 0.33 in all patients of the Slit-like group. In conclusion, because small ventricles after shunt strongly suggest the presence of ventricular tautness, the lateral ventricular size should be maintained at more than 0.33 on the Evans' index in shunted children at an age of 3 or more than 3 years.

Adolescent↗
PubMed1998

Serial MR observation of cortical laminar necrosis caused by brain infarction.

To examine the chronological changes characteristic of cortical laminar necrosis caused by brain infarction, 16 patients were repeatedly examined using T1-, T2-weighted spin-echo, T2*-weighted gradient echo, fluid attenuated inversion recovery (FLAIR) images, and contrast enhanced T1-weighted images at 1.0 or 1.5 T. High intensity cortical lesions were visible on the T1-weighted images from 2 weeks after ictus and became prominent at 1 to 3 months, then became less apparent, but occasionally remained at high intensity for 2 years. High intensity cortical lesions on FLAIR images became prominent from 1 month, and then became less prominent from 1 year, but occasionally remained at high intensity for 2 years. Subcortical lesions did not display high intensity on T1-weighted images at any stage. On FLAIR images, subcortical lesions initially showed slightly high intensity and then low intensity from 6 months due to encephalomalacia. Cortical lesions showed prominent contrast enhancement from 2 weeks to 3 months, but subcortical lesions were prominent from 2 weeks only up to 1 month. T2*-weighted images disclosed haemosiderin in 3 of 7 patients, but there was no correlation with cortical short T1 lesions. Cortical laminar necrosis showed characteristic chronological signal changes on T1-weighted images and FLAIR images. Cortical short T1 lesions were found not to be caused by haemorrhagic infarction.

Adult↗
PubMed1998

Intracranial aneurysms in identical twins.

BACKGROUND: Though familial intracranial aneurysms are well documented, only a few cases of intracranial aneurysms in identical twins have been reported. CASE REPORT: Our patient, a 46-year-old woman, presented with a subarachnoid hemorrhage (SAH) due to a ruptured aneurysm. At the age of 36, her identical twin sister had also suffered SAH from a ruptured aneurysm. Both twins were treated successfully. CONCLUSION: The likelihood of the occurrence of an aneurysm may be higher for a twin whose identical twin has developed an aneurysm than for the general population. Therefore, it is reasonable to perform certain screening procedures for aneurysms on an asymptomatic twin when the other presents with SAH due to a ruptured aneurysm.

Diseases in Twins↗
PubMed1998

Trans-kingdom conjugation offers a powerful gene targeting tool in yeast.

Gene targeting is one of the powerful techniques used to investigate eukaryotic genes. In a typical eukaryotic microbe, Saccharomyces cerevisiae yeast, we examined trans-kingdom conjugation between Escherichia coli bacterium and yeast as a gene targeting tool. Here, it is shown that trans-kingdom conjugation effectively induced gene replacement even on yeast's target loci (e.g. ura3-52 allele) which is never targeted by conventional transformation. This clearly indicates that trans-kingdom conjugation offers a very powerful gene targeting tool in yeasts. In fact, Southern hybridization analysis of transconjugants distinctly verified the accuracy in the conjugative gene replacement. The efficiency of gene replacement was about 0.4 x 10(-7) per recipient yeast. This is enough to sustain gene targeting with gene replacement by trans-kingdom conjugation. We also discuss the mechanism of conjugative gene replacement.

Conjugation, Genetic↗
PubMed1998

Mouse mammary carcinoma cell line (BALB/c-MC) stimulates osteoclast formation from mouse bone marrow cells through cell-to-cell contact.

We recently reported that numerous osteoclasts (OC) were formed in cocultures of some mouse cancer cell lines and bone marrow cells. In this study, we examined mechanisms by which one of the cell lines, BALB/c-MC, induces OC. BALB/c-MC dose dependently stimulated OC formation in cocultures. In cocultures where direct cell-to-cell contact between BALB/c-MC and bone marrow cells was inhibited by membrane filters, OC formation was not stimulated. The stimulation of OC formation in the coculture was completely abolished by adding 10(-7)-10(-6) mol/L indomethacin. The concentration of prostaglandin E2 (PGE2) in the culture media of cocultures with cell-to-cell contact was higher than that of cocultures without cell-to-cell contact or marrow cultures alone, and it reached levels sufficient to induce OC (11.9 +/- 5.3 ng/mL [about 3.4 x 10(-8) mol/L]). When BALB/c-MC or bone marrow cells were fixed with formalin and then cocultured with bone marrow cells or BALB/c-MC, respectively, the concentration of PGE2 in the culture media of cocultures of fixed BALB/c-MC and bone marrow cells increased, whereas that of cocultures of BALB/c-MC and fixed bone marrow cells did not increase. These results indicate that BALB/c-MC stimulate OC formation through direct cell-to-cell contact with bone marrow cells, and PGE2 released from bone marrow cells through direct cell-to-cell contact are involved in OC formation by the cell line.

Animals↗
PubMed1998

Osteoclastogenesis inhibitory factor exhibits hypocalcemic effects in normal mice and in hypercalcemic nude mice carrying tumors associated with humoral hypercalcemia of malignancy.

Osteoclastogenesis inhibitory factor (OCIF) is a novel secreted protein that inhibits osteoclastogenesis both in vitro and in vivo. In this study, we examined the effects of OCIF on serum calcium (Ca) concentrations in normal mice and in hypercalcemic nude mice carrying tumors associated with humoral hypercalcemia of malignancy. In normal mice, a single intraperitoneal injection of OCIF reduced serum Ca levels in a dose-dependent manner. Significant decrease in serum Ca (by 1.6 +/- 0.3 mg/dL, n = 5) was observed 2 h after the injection of OCIF at 20 mg/kg and the hypocalcemic effect continued for up to 12 h. Serum phosphate (Pi) concentrations also decreased in response to OCIF. Urinary excretion of Ca, Pi, and creatinine did not change significantly after injection of OCIF or vehicle. In hypercalcemic, tumor-bearing nude mice, a single intraperitoneal injection of OCIF at 20 mg/kg resulted in a dramatic decrease in serum Ca (maximal decrease 2.8 +/- 0.37 mg/dL, n = 11), which continued for up to 24 h. The results suggest that OCIF decreased serum Ca through its inhibitory effect on bone resorption. Furthermore, it is suggested that OCIF has therapeutic potential for the treatment of hypercalcemic conditions such as malignancy-associated hypercalcemia.

Animals↗
PubMed1998

Maternal thyroid function in multiple pregnancy: the variable thyrotropic activity of human chorionic gonadotropin.

The present study was undertaken to evaluate thyroid function and thyrotropic action of hCG in multiple pregnancy. We examined serum samples from 9 multiple pregnant women (3 triplets and 6 twins) and 27 singleton pregnant women as control subjects. Serum hCG levels in multiple pregnancy were higher than those in singleton pregnancy in the second and third trimesters (P < 0.01). The mean free T3 and T4 concentrations in multiple pregnancy did not differ from those in singleton pregnancy in each trimester. Serum hCG levels showed a statistically significant positive correlation with free T3 and T4 levels in singleton pregnancy (P < 0.001). However, these correlations were not observed in multiple pregnancy. Thyroid stimulation activity (TSA) determined by cAMP accumulation in FRTL-5 cells in multiple pregnancy sera was significantly higher than that in singleton pregnancy in the first trimester (P < 0.05), but did not differ in the second and third trimesters. Moreover, TSA did not show any correlation with serum hCG levels in multiple pregnancy in contrast with the results in normal pregnancy. A bioactivity/immunoreactivity ratio of hCG in multiple pregnancy was lower than in singleton pregnancy in the second and third trimesters. The discrepancy between immunoreactivity and thyrotropic activity of hCG may be caused by the variable thyrotropic potency of heterogeneous hCG molecules in multiple pregnancy.

Adult↗
PubMed1998

Granulocyte-macrophage colony-stimulating factor expressed in T cells mediates immunity against herpes simplex virus type 1 encephalitis.

A model of herpes simplex virus type 1 (HSV-1) infection was developed in rats to study systemic immune responses elicited by intravitreous inoculation of the virus. HSV-1 inoculation led to distinct granulocyte-macrophage colony-stimulating factor (GM-CSF)-producing memory T cells, which did not develop in rats inoculated with either HSV-1 intraperitoneally or inactivated HSV-1 intravitreously. On subsequent intraperitoneal viral boosting, systemic GM-CSF production was elicited as a secondary immune response that caused neutroeosinophilia. To examine the role of GM-CSF in anti-herpetic immunity, cytokine-producing and -nonproducing rats were intravitreously challenged with HSV-1, which causes lethal encephalitis. Only intravitreously primed rats were protected upon production of GM-CSF. Furthermore, pretreatment with recombinant GM-CSF protected unimmunized rats against the encephalitis. It is thus strongly suggested that the production of GM-CSF leads to anti-HSV-1 immunity against the transneuronal spread of challenged HSV-1 within the visual system.

Adoptive Transfer↗
PubMed1998

Induction of type 2 deiodinase activity by cyclic guanosine 3',5'-monophosphate in cultured rat glial cells.

We investigated the effects of cyclic guanosine 3',5'-monophosphate (cGMP) on type 2 iodothyronine deiodinase (D2) in cultured rat glial cells. Rat glial cells were cultured in Dulbecco's modified Eagle's medium supplemented with 15% fetal bovine serum. When cells were cultured in the presence of 8-bromo cGMP (8-Br cGMP), an analogue of cGMP, D2 activity was increased in a time- and concentration-dependent manner. Lineweaver-Burk plots revealed that the stimulation of D2 activity by 8-Br cGMP (10(-3) M) was associated with fivefold increase in maximum velocity but without a significant change in Michaelis-Menten constant, suggesting that cGMP increases D2 activity via new enzyme synthesis. Both atrial natriuretic peptide (ANP) and C-type natriuretic peptide (CNP) are well known to increase the intracellular cGMP level via their guanylate cyclase-linked receptors in rat glial cells. In the present study, ANP (10(-6) M) and CNP (10(-6) M) significantly increased the D2 activity in rat glial cells (1.9-fold [ANP] or 2.3-fold [CNP] compared with control activity, respectively). Northern blot analysis demonstrated that D2 mRNA level increased in the presence of 8-Br cGMP (10(-3) M), and reached a plateau (six-fold) after 4 hours of incubation. The increment of D2 mRNA level by 8-Br cGMP was comparable with the increase of the D2 activity by this agent. Our data suggest that cGMP induces rat D2 activity, at least in part, at the pretranslational level, and that ANP and CNP increase D2 activity most likely via their guanylate cyclase-linked receptors in rat glial cells.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1998

Identification of metabolites of nerve agent VX in serum collected from a victim.

A human serum sample collected from a victim of the Osaka VX incident was analyzed according to our developed technique for metabolites of VX. Gas chromatography-mass spectrometry (GC-MS) in full-scan electron impact and chemical ionization modes were used, and, for more reliable confirmation, GC-MS-MS was also employed. In the serum sample, both ethyl methylphosphonic acid and 2-(diisopropylamino-ethyl)methyl sulfide were detected. These results indicated that the techniques using GC-MS and GC-MS-MS were applicable to biological samples such as serum. These results also provide the first documented, unequivocal identification of the specific metabolites of VX in victim's serum and, furthermore, clarify a part of the metabolic pathway of VX in the human body.

Adult↗