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Biomedical subjects

M Nishijima

Publications and source records attributed to M Nishijima.

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

Both sphingolipids and cholesterol participate in the detergent insolubility of alkaline phosphatase, a glycosylphosphatidylinositol-anchored protein, in mammalian membranes.

SPB-1, a Chinese hamster ovary cell variant defective in serine palmitoyltransferase activity for sphingolipid synthesis, provides a useful system for studying the effects of sphingolipids and/or cholesterol deprivation on cellular functions and membrane properties. To investigate whether there was an interaction among sphingolipids, cholesterol, and glycosylphosphatidylinositol (GPI)-anchored proteins in biological membranes, we introduced human placental alkaline phosphatase (PLAP) in SPB-1 and in wild type cells by stable transfection and examined the effects of sphingolipid and/or cholesterol deprivation on the solubility of PLAP in Triton X-100. Although the PLAP solubility of the membranes isolated from the control cells in Triton X-100 was only 10%, deprivation of sphingolipid and cholesterol further enhanced the solubility, which reached 50% when both sphingolipids and cholesterol were deprived. The enhanced solubility was suppressed to the control level by metabolic complementation with exogenous sphingosine and cholesterol. The sphingolipid and cholesterol content of the isolated membranes changed independently, eliminating the possibility that sphingolipid deprivation induced a reduction in cellular cholesterol and enhanced PLAP solubility and vice versa. It was also unlikely that the enhanced solubility was due to structural changes in PLAP molecules since, regardless of sphingolipid and cholesterol deprivations, almost all PLAP had the GPI-anchor moiety and there were no differences in the apparent molecular weight of the protein in supernatant and precipitate fractions of the detergent-treated membranes. In addition, the expression level of caveolin in the isolated membranes was not significantly affected by sphingolipids and/or cholesterol depletion. These results indicated that both sphingolipids and cholesterol were involved in the PLAP insolubility and suggested that these lipids coordinately played a role in formation of Triton X-100-resistant complexes.

Acyltransferases↗
PubMed1995

Plasma platelet-derived growth factor-B chain is elevated in patients with extensively large brain tumour.

The plasma concentration of the platelet-derived growth factor (PDGF)-B chain and the plasma platelet factor 4 (PF4) levels were measured in 17 healthy controls and 55 brain tumour patients. In the 17 normal controls, the plasma PDGF-B and PF4 levels were 523 +/- 157 pg/ml (mean +/- SD) and 84 +/- 37 ng/ml, respectively. In the brain tumour patients, these values were 881 +/- 854 pg/ml and 93 +/- 64 ng/ml, respectively. The plasma PDGF-B concentration was elevated above the upper limit of normal individuals in 12 (22%) of the 55 patients. However, since the corresponding PF4 levels suggested the platelet activation, the increased plasma PDGF-B may have originated from platelets. To address this, platelet releasing experiments were performed on citrated blood samples from 5 normal individuals. The plasma PDGF-B and PF4 levels from the 17 normal controls and those observed in the platelet releasing experiments correlated with a regression line of Y = 240 + 4.86X (Y:PDGF, X:PF4). There were only 6 (11%) patients whose plasma PDGF-B level was elevated above the 95% confidence limit estimated from the corresponding PF4 value. In these patients, the tumour volumes were extensively large, and those elevated PDGF-B values decreased after treatment and became elevated again in three patients with recurrent glioblastoma. Although the plasma tumour-derived PDGF-B was detected only in an extensively large brain tumour, it might be a useful plasma marker evaluating the effects of therapy and prognosis in such patients.

Adolescent↗
PubMed1995

Dense Community of Hyperthermophilic Sulfur-Dependent Heterotrophs in a Geothermally Heated Shallow Submarine Biotope near Kodakara-Jima Island, Kagoshima, Japan.

Microbial communities in marine hydrothermal sediments (0 to 30 cm deep) in an inlet of Kodakara-Jima Island, Kagoshima, Japan, were studied with reference to environmental factors, especially the presence of amino acids. The study area was shallow, and the sea floor was covered with sand through which hot volcanic gas bubbled and geothermally heated water seeped out. The total bacterial density increased with depth in the sediments in parallel with a rise in the ambient temperature (80(deg)C at the surface and 104(deg)C at a depth of 30 cm in the sediments). As estimated by most-probable-number studies, hyperthermophilic sulfur-dependent heterotrophs growing at 90(deg)C dominated the microbial community (3 x 10(sup7) cells (middot) g of sediment(sup-1) at a depth of 30 cm in the sediments), followed in abundance by hyperthermophilic sulfur-dependent facultative autotrophs (3.3 x 10(sup2) cells (middot) g of sediment(sup-1)). The cooler sandy or rocky floor surrounding the hot spots was covered with white bacterial mats which consisted of large Beggiatoa-like filaments. Both the total organic carbon content, most of which was particulate (75% in the surface sediments), and the amino acid concentration in void seawater in the sediments decreased with depth. Amino acids, both hydrolyzable and free, constituted approximately 23% of the dissolved organic carbon in the surface sediments. These results indicate that a lower amino acid concentration is probably due to consumption by dense populations of hyperthermophilic sulfur-dependent heterotrophs, which require amino acids for their growth and thus create a gradient of amino acid concentration in the sediments. The role of primary producers, which supply essential amino acids to sustain this microbial community, is also discussed.

Journal Article↗
PubMed1995

Structural analysis of alkaline-soluble polysaccharide, P-1, from the kernels of Prunus mume Sieb. et Zucc.

A polysaccharide fraction extracted with cold 0.5 M NaOH from the kernels of Prunus mume exhibited some biological activities. A polysaccharide, P-1, was purified from the 0.5M NaOH extract by ion-exchange chromatography and gel-filtration. The results of the structural analysis of P-1 to determine the relationship between the activities and the structure are described in this paper. In the mild acid hydrolysis of P-1, the nondialyzable hydrolysate (I-3) believed to be its core portion was obtained. The yield of I-3 was 26.0% and contained 59.8% uronic acid as galacturonic acid (GalA). The neutral sugars of I-3 were composed of rhamnose, xylose and galactose in a molar ratio of 1.0:3.4:0.3 following analysis by gas-liquid chromatography. The molecular weight of I-3 was estimated to be ca. 14000 by gel-filtration on Toyopearl HW55F. I-3 exhibited the mitogenic activity toward spleen cells as well as P-1. These facts appeared to confirm that I-3 was the core part of P-1 and important for its biological activity. I-3 was successfully reduced by the Taylor and Conrad method to avoid so much repetition. Methylation analysis of the reduced hydrolysate by gas-liquid chromatography and gas chromatography-mass spectroscopy showed that the ratio of 1,4-linked galactopyranosyl and 1,3,4-linked galactopyranosyl residues were significantly increased in comparison with native I-3. These results suggested that I-3 was composed of 1,4- and 1,3,4-linked galacturonic acid residues in the main chain.

Animals↗
PubMed1995

Oxytocin-induced natriuresis mediated by the renal kallikrein-kinin system in anesthetized male rats.

Intravenous infusion of oxytocin (OT) (10-100 nmol/kg/30 min) to 8-week-old anesthetized male rats resulted in a dose-dependent increase in urine volume, which showed a peak value 30-45 min after the start of OT-infusion. Urinary excretions of sodium, chloride and potassium were also increased by OT, showing peak values at 30-45 min, without any increase in the creatinine level. The natriuresis by OT was accompanied by increased excretion of urinary active kallikrein, which showed a peak value 15 min after the start of OT-infusion. The urinary kinin level was also increased. Intravenous infusion of a kallikrein inhibitor, aprotinin (15 mg/kg/90 min), when started 30 min before the OT-infusion, significantly inhibited the OT-induced increase in urine volume and urinary excretion of sodium, chloride and potassium. Intravenous infusion of a bradykinin B2 antagonist, Hoe 140 (D-Arg[Hyp3,Thi5,D-Tic7,Oic8]BK, 4.5 mg/kg/90 min), when started 30 min before the OT-infusion, significantly inhibited the OT-induced increases in urine volume and urinary excretion of sodium and chloride, but not that of potassium. These results indicate that the OT-infusion induces natriuresis in male rats, and more than half of the natriuresis is mediated by a concomitant increase in excretion of urinary active kallikrein and the kinin generated.

Anesthesia↗
PubMed1995

Induction of cyclooxygenase type-2 (COX-2) in rat endometrium at the peak of serum estradiol during the estrus cycle.

We investigated the induction of cyclooxygenase (COX) in rat endometrium during the estrus cycle. The estrus cycle was divided into five stages (proestrus, estrus, diestrus-1, diestrus-2, diestrus-3) by cytological observation of vaginal smears. COX-1 was detected in the endometrium during all five stages of the estrus cycle. In contrast, COX-2 in the endometrium was detectable only in three stages (diestrus-3, proestrus, estrus) and showed a peak at diestrus-3, coinciding with the peak in serum estradiol level, suggesting the estradiol-dependent induction of COX-2.

Animals↗
PubMed1995

Antiproliferative effect of multiple autocrine loop blockade in human malignant glioma cell lines.

The effects of specific antibodies against growth factors and receptors on deoxyribonucleic acid (DNA) synthesis in two established human glioma cell lines, A172 and TM-1, were examined. Anti-platelet-derived growth factor (PDGF), anti-basic fibroblast growth factor (bFGF), and anti-epidermal growth factor receptor (EGF-R) antibodies inhibited thymidine incorporation by both cell lines in serum-free medium. Antibody specific to transforming growth factor-alpha only slightly suppressed DNA synthesis by both cell lines. Although the antiproliferative effects of anti-PDGF and anti-bFGF antibodies decreased in serum-supplemented medium, the effect of anti-EGF-R antibody was little changed. The combination of anti-PDGF, anti-bFGF, and anti-EGF-R antibodies significantly inhibited thymidine incorporation by the two cell lines even in serum-supplemented medium. This preliminary study suggests that simultaneous blockade of multiple autocrine loops may provide a new approach to the treatment of human malignant gliomas.

Antibodies, Monoclonal↗
PubMed1995

Clinical study of enlarged infundibular dilation of the origin of the posterior communicating artery.

Although some aneurysmal dilations of the origin of the posterior communicating artery (PCoA) that are revealed on carotid angiogram are true aneurysms or preaneurysmal lesions, the authors warn that diagnosis should not be based only on the size and shape of the dilation, especially when the PCoA does not fill. In the present retrospective study, the authors analyzed intraoperative and angiographic findings in 32 patients with 34 lesions of the PCoA that were preoperatively diagnosed as aneurysms. Only 10 of the lesions were true aneurysms (six cases) or enlarged infundibular dilations with reddish bulges (that is, preaneurysmal bulge; four cases) at the origin of the PCoA. All of the other 24 lesions, including one lesion with PCoA occlusion, were merely enlarged infundibular dilations without any wall abnormality. A well-developed PCoA was observed only in cases of true aneurysm and dilation with reddish bulge. No other clinical or angiographic characteristics proved useful in identifying the type of lesions. These findings may be helpful to the physician in evaluating the clinical features of such lesions and in determining the diagnosis of enlarged infundibular dilation of the PCoA.

Aged↗
PubMed1995

[Enzyme immunoassay of pesticide residues in foods].

Analytical techniques for pesticide residues in food include gas chromatography (GC), gas chromatography/mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC). These procedures are time consuming, cumbersome and require specialized instrumentation. A number of enzyme immunoassay methods for pesticide have appeared in recent years. In addition, nowadays a lot of immunoassay kits for various kinds of pesticide are in the market. The assay offers alternative means that is more sensitive, faster and cost-effective than previous methods. However, it is subject to problems that the assay does not suit multi-residue analysis and has possibility to encounter interferences which would affect the assay precision in case of some crops. Assuming that researcher knows which pesticide were applied to the analyzed crops beforehand, the pesticide would be detected easily by immunoassay. Also, when suitable sample kit for analyzed pesticide is available, the assay could be an excellent screening tool for large number of food samples. In conclusion, it will be necessary to consider analytical purpose to confirm utility of immunoassay when applying to pesticide analysis.

Food Analysis↗
PubMed1994

Liquid chromatographic determination of carnitine by precolumn derivatization with pyrene-1-carbonyl cyanide.

A method is described for the determination of carnitine chloride in pharmaceutical preparations by precolumn derivatization and high-performance liquid chromatography (HPLC). Carnitine chloride is derivatized by reaction with pyrene-1-carbonyl cyanide (PCC) in dimethyl sulphoxide. The PCC derivative of carnitine is then used for quantitative HPLC analysis on a cation-exchange column with fluorescence detection. The calibration graph was linear over a sample concentration range from 2.0 to 20 micrograms/ml; the limit of detection was 0.5 microgram/ml under the conditions studied. The proposed method was applied satisfactorily to the determination of carnitine chloride in pharmaceutical preparations.

Carnitine↗
PubMed1994

Platelet-activating factor (PAF) and the development of chronic subdural haematoma.

Platelet activating factor (PAF) content and PAF-acetylhydrolase (PAFAH) activity were measured in the plasma and haematoma of 34 chronic subdural haematoma (CSH) patients. The plasma PAF level in patients with CSH was higher than that in healthy controls. Although there was no correlation between the plasma PAF levels and the interval between the onset of symptoms and the day of sampling, namely, the interval after bleeding, the haematoma PAF level gradually decreased according to the interval after the onset of symptoms. There was no difference between plasma PAFAH activity in patients with CSH and that in healthy controls, and haematoma enzyme activity gradually increased correlated with the interval between the onset of symptoms and surgery. In addition, the localization of PAF in haematoma capsules was histochemically determined. PAF was solely localized to the peri-sinusoidal vessels in the outer membrane of haematoma capsules. Based on these biochemical and histochemical studies, we speculated that PAF may play a role in the development of chronic subdural haematomas.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1994

Dural arteriovenous fistulae involving the transverse-sigmoid sinus and foramen magnum.

The authors present a rare case of dural arteriovenous fistulae (AVFs) involving both the transverse-sigmoid sinus and the foramen magnum, which was treated successfully with multi-staged endovascular procedures. The transverse-sigmoid sinus, which was thrombosed proximally and distally, was occluded by transarterial embolization followed by intraoperative embolization of the sinus using platinum coils. The dural AVF involving the foramen magnum was occluded via a transvenous approach.

Arteriovenous Fistula↗