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Biomedical subjects

R Nakayama

Publications and source records attributed to R Nakayama.

At least 91 records · Page 5Linked to original sources
PubMed1985

Identification of prostaglandin E metabolites from primary cultures of rat hepatocytes.

Primary cultured rat hepatocytes were shown to bind to prostaglandins E1, E2, D2 and F2 alpha and then rapidly degrade at 37 degrees C. 6-Ketoprostaglandin F1 alpha and thromboxane B2, which are inactive metabolites of prostaglandin I2 and thromboxane A2, respectively, bound less effectively to the cells and were not degraded. Incubation of hepatocytes with 3H-labeled prostaglandins, treatment of the cells at an acidic pH, and analysis of the acid solution by thin-layer chromatography, showed that the radioactive material was bound to the cell surface and consisted of intact prostaglandin and its metabolites. The metabolites of prostaglandin E that accumulated in the culture medium were purified by silicic acid column and silica gel thin-layer chromatographies, and analyzed by gas chromatography-mass spectrometry. Prostaglandins E1 and E2 gave exactly the same metabolites, which were identified as dinorprostaglandin E1 and tetranorprostaglandin E1, representing products of beta-oxidation. These data suggest that part of the carboxyl side chain of prostaglandins, but not of inactive metabolites, was eliminated by a beta-oxidation system in the hepatocytes, while the rest of the molecule was not degraded appreciably and was rapidly transferred to the outside of the cells.

Animals↗
PubMed1985

Generation of acetyl glyceryl ether phosphorylcholine from the rat skin and muscle tissues stimulated by moxibustion.

Platelet-activating factor was obtained from the rat skin and muscle tissues which were stimulated by moxibustion. It showed a typical aggregation pattern on interaction with washed rabbit platelets but when it was treated with phospholipases A2 and C, and CV 3988 the aggregation activity was lost. Platelet-activating factor was hydrolysed with phospholipase C and the resulting lipid product was converted to the tert-butyldimethylsilyl derivative. After purification by thin layer chromatography, the ether type of derivative was analysed by a selected ion monitoring technique of gas chromatography-mass spectrometry. 1-0-Hexadecyl-2-acetyl-sn-glyceryl-3-phosphorylcholine only was identified.

Animals↗
PubMed1985

Hemodynamic effects of intravenous PGE1 on patients with arterial occlusive disease of the leg.

In 42 patients with arterial occlusive disease of the leg, the hemodynamic effects of prostaglandin E1 (PGE1) given intravenously were studied. Blood pressure of the leg and crest time of the pulse wave did not change significantly, while increases in blood flow at the calf and foot, amplitude of the pulse wave, velocity, and skin temperature at the foot and toes were significant. Skin temperature of the calf dropped significantly. The increase in blood flow, velocity, and skin temperature was significantly more dominant in the distal part of the leg than that in the proximal part. In separate observation of individuals, 12 of the 66 legs with arterial occlusive disease (18%) showed a decrease in skin temperature at the toes. The steal phenomenon was observed most frequently in limbs with rest pain, gangrene, or both.

Adult↗
PubMed1985

Assessment of venous insufficiency using photoplethysmography: a comparison to strain gauge plethysmography.

Simultaneous photoplethysmographic (PPG) and strain gauge plethysmographic (SPG) recordings were obtained in normal subjects and patients with venous insufficiency. In PPG tracings, a so called "negative segment," which represented a further fall below the baseline after exercising, was often observed. This negative segment is produced by blood flow from the superficial to the deep veins during relaxation, which indicates that PPG can be used to assess the circulatory hemodynamics in the skin. PPG and SPG tracings from limbs with primary varicosis showed a shorter refilling time after exercise than those from normal limbs at the distal as well as the midcalf levels. The mean refilling time measured at the distal level by PPG was unaffected by tourniquets applied proximal to the transducer, indicating that the PPG tracings determined at the distal level were not always influenced by the reflux of blood through the incompetent saphenous system, but by altered cutaneous circulation. SPG was of greater diagnostic value for deep venous disease than PPG. From these results, it would be concluded that PPG in combination with SPG offers a rational approach to the assessment and the understanding of the pathophysiology of venous diseases.

Adult↗
PubMed1984

Dietary induction of glucose-6-phosphate dehydrogenase synthesis.

The effect of dietary carbohydrate on rat liver glucose-6-phosphate dehydrogenase synthesis has been determined by using a method which can accurately quantitate relative rates of synthesis as low as 0.001 percent of total protein synthesis. Hepatocytes were incubated with (3H) leucine for 60 min and G6PD was separated from all other proteins by immunoprecipitation and electrophoresis on two-dimensional O'Farrell gels. The relative rate of synthesis of G6PD increased 70-fold (from 0.0015 to 0.11% of total protein synthesis) in hepatocytes from fasted rats refed a high carbohydrate diet. We have concluded that the 20-30 fold dietary induction of G6PD is due to a 70 and 3 fold increase in synthesis and degradation, respectively.

Animals↗
PubMed1984

Kinetics for changes in enzyme synthesis and mRNA content and hormones required for induction of 6-phosphogluconate dehydrogenase in hepatocytes.

Rats fasted for 2 days were refed a 60% glucose diet for varying periods of time in order to follow the kinetics for changes in 6-phosphogluconate dehydrogenase synthesis and mRNA content. Hepatocytes isolated from control or induced rats were incubated with actinomycin D and the rate of decline in 6-phosphogluconate dehydrogenase mRNA was determined by translating RNA in a nuclease-treated reticulocyte lysate. The half-life for 6-phosphogluconate dehydrogenase mRNA under both of these conditions was about 2 h. Thus, increases in transcription or the processing of nuclear RNA may increase 6-phosphogluconate dehydrogenase mRNA during the dietary induction of this enzyme. Hepatocytes prepared from fasted rats were cultured with 5% serum and various hormones and energy sources. If hepatocytes were isolated from thyroidectomized rats and cultured in serum from a thyroidectomized calf, the 4-fold induction of 6-phosphogluconate dehydrogenase was primarily dependent upon added insulin. In the presence of optimal insulin concentrations (10(-7) M) triiodothyronine slightly stimulated 6-phosphogluconate dehydrogenase induction. The gut hormones somatostatin and secretin had no effect on 6-phosphogluconate dehydrogenase induction in cultured hepatocytes. Hepatocytes cultured in carbohydrate-free medium and 5% serum required added insulin for maximal induction. 8-Br-cGMP did not significantly affect 6-phosphogluconate dehydrogenase induction in hepatocytes either in the presence or absence of added insulin. Dibutyryl cAMP did not alter the time course or extent of 6-phosphogluconate dehydrogenase induction in cultured hepatocytes. We have concluded that under these conditions insulin is a potent signal regulating the levels of 6-phosphogluconate dehydrogenase mRNA and that this induction is not mediated by cyclic nucleotides.

Animals↗
PubMed1984

Isolation and genetic characterization of a thymineless death-resistant mutant of Escherichia coli K12: identification of a new mutation (recQ1) that blocks the RecF recombination pathway.

An Escherichia coli K12 mutant resistant to thymineless death (TLD) was isolated, and its genetic analysis led us to identify a new mutation (recQ1) located between corA and metE on the standard linkage map. The mutation was found to result in increased sensitivity to ultraviolet light and deficiency in conjugational recombination when placed in the recBC sbcB background, indicating that it blocked the RecF pathway of recombination. It seemed likely that this mutation is also capable of causing partial resistance to TLD, but we reserve the possibility of a separate mutation closely linked to recQ1 giving rise to this phenotype. The original mutant was shown to carry an additional mutation probably in the vicinity of the uhp locus, which was also required for the full TLD resistance of the mutant to be expressed.

Chromosome Mapping↗
PubMed1984

Leakage of glutathione from bacterial cells caused by inhibition of gamma-glutamyltranspeptidase.

Glutathione leaked from cells of Proteus mirabilis grown in medium containing an inhibitor of gamma-glutamyltranspeptidase. In medium containing 100 mM L-serine and borate, up to 300 microM glutathione accumulated. L-Serine in the medium was consumed during the logarithmic phase of growth, gamma-glutamyltranspeptidase activity was restored, and glutathione decreased in the medium. In the presence of 2 mM 6-diazo-5-oxo-L-norleucine, cells increased normally, gamma-glutamyltranspeptidase was inhibited completely, and the maximum concentration of glutathione which accumulated in the medium was 20 microM. The glutathione content of cells rose before leakage began. Glutathione leaked from intact cells of other bacteria, although to a lesser extent than was seen with P. mirabilis.

Bacterial Physiological Phenomena↗
PubMed1984

Purification and properties of gamma-glutamyltranspeptidase from Proteus mirabilis.

gamma-Glutamyltranspeptidase was purified ca. 15,200-fold from cell-free extracts of Proteus mirabilis to electrophoretic homogeneity and then crystallized. The enzyme has an estimated molecular weight of 80,000 and consists of two different subunits with molecular weights of ca. 47,000 and 28,000. The purified enzyme catalyzed hydrolysis and transpeptidation of various gamma-glutamyl compounds, including the oxidized and reduced forms of glutathione, gamma-glutamyl compounds of L-phenylalanine, L-tyrosine, L-histidine, L-alpha-aminobutyrate, L-leucine, and p-nitroaniline. Glycylglycine, L-phenylalanine, L-methionine, L-histidine, L-tryptophan, and L-isoleucine were good acceptors of the gamma-glutamyl moiety in the transpeptidation reaction. Km values for gamma-glutamyl compounds were on the order of 10(-4) to 10(-5) M, and those for acceptor peptides and amino acids were on the order of 10(-2) to 10(-3) M. The enzyme was inhibited by L-serine plus borate and 6-diazo-5-oxo-L-norleucine, which are inhibitors of gamma-glutamyltranspeptidases isolated from mammals. Various amino acids alone were found to inhibit the transpeptidation competitively with a gamma-glutamyl donor. Kinetic analysis suggested that the reaction sequence of substrate binding and product release proceeds according to a ping pong bi bi mechanism.

Amino Acids↗
PubMed1984

gamma-Glutamyltranspeptidase from Proteus mirabilis: localization and activation by phospholipids.

Antiserum was prepared against the purified gamma-glutamyltranspeptidase (EC 2.3.2.2) of Proteus mirabilis. The antiserum inactivated the gamma-glutamyltranspeptidase activities of both purified enzyme and intact cells. Native cells were agglutinated with the antibody. Immunocytochemical studies with indirect immunofluorescence and electron microscopy analysis suggested that gamma-glutamyltranspeptidase is localized on the surface of the cell. Its distribution in the cell wall or periplasmic space or both was also confirmed by the treatment of cells with lysozyme-EDTA. The purified enzyme was activated by the addition of membrane phospholipids isolated from the same bacterium. The hydrolysis activity was stimulated more than the transpeptidation activity by several phospholipids.

Enzyme Activation↗
PubMed1984

Radioimmunoassay for serum levels of an anti-androgen TSAA-291 (Oxendolone) in rats.

A simple radioimmunoassay method was established to determine serum levels of a steroidal anti-androgen, TSAA-291 (Oxendolone, 16 beta-ethyl-17 beta-hydroxy-4-estren-3-one) utilizing ether-extract of serum. Using an antiserum raised against TSAA-291-3-oxime-BSA conjugate in a rabbit, a standard curve was obtained in the assay range from 30 pg to 12 ng/tube. Intra- and inter-assay coefficients of variation were calculated to be 11 and 21%, respectively. Recovery rate of unlabeled TSAA-291 was 84%. Cross-reaction with endogenous steroids was less than 0.2%. TSAA-291 estimates were compared with those determined after further purification on a Celite column, or with those assayed with a gas-liquid chromatograph. The difference between these estimates was less than 16 and 25%, respectively, suggesting little contribution of the metabolites of TSAA-291 to the estimates by the radioimmunoassay. After successive treatments of male rats with TSAA-291 in an aqueous suspension in daily doses of 5, 15 and 50 mg/kg body weight for two weeks, serum TSAA-291 levels were determined by the radio immunoassay and calculated to be 22.7, 76.9 and 194.9 ng/ml, respectively.

Animals↗
PubMed1984

Pulmonary veno-occlusive disease in an elderly man: case report and review of the literature.

A 75-year-old man complaining of dyspnea and having sings of postcapillary pulmonary hypertension was diagnosed as pulmonary veno-occlusive disease and confirmed at autopsy. This is the oldest case ever reported. Almost all the small veins 2 mm or less in external diameter were partially or nearly completely occluded by intimal fibrous tissue, and the obstructive changes in the pulmonary arteries were much more limited. Pulmonary veno-occlusive disease is a rare, almost inevitably fatal disease of unknown etiology which has only recently been separated clearly from primary pulmonary hypertension as a distinct entity. Chest roentgenogram finding suggesting postcapillary pulmonary hypertension is a clue to a diagnosis and differentiates this from two other causes of clinical primary pulmonary hypertension, that is, recurrent pulmonary embolism and plexogenic pulmonary arteriopathy.

Aged↗
PubMed1984

Biphasic release of thyrotropin in response to thyrotropin-releasing hormone (TRH) from rat anterior pituitary cells in vitro: possible dependence on protein synthesis.

Mechanisms related to the biphasic release of TSH were studied using primary cultured cells of the rat anterior pituitary gland on micro-carrier beads in a superfusion system. Release of TSH in response to continuous exposure to TRH exhibited a biphasic pattern; the first phase was characterized by a rapid, transient and high-rate release (phase I) and the second phase by a chronic and low-rate release (phase II). The shift of the release from phase I to phase II occurred by treatment with TRH at concentrations from submaximal to maximal. When the Ca2+ concentration in the medium was decreased, the phase I release was partially inhibited, while the phase II release was completely inhibited, suggesting a difference between the mechanisms in phase I and phase II release. The phase I release was not suppressed by cycloheximide. This protein synthesis-independent release of phase I seemed to be linked to the intracellular releasable pool of TSH. The phase II release was suppressed by the presence of a protein synthesis inhibitor. After the phase II release was suppressed by cycloheximide, the magnitude of phase I release in response to re-exposure to TRH markedly decreased. The decreased phase I release in response to TRH was observed with the cells which were previously stimulated by high K+ instead of TRH, suggesting that the decrease in the response of phase I reflects the depletion of a releasable pool of TSH rather than homologous desensitization of thyrotrophs with TRH. These results suggest that the phase I release of TSH depends on a portion of the previously prepared-releasable pool while phase II release depends on previously prepared plus newly prepared pools of TSH. Replenishment of the releasable TSH pool was considered to involve protein synthesis.

Animals↗
PubMed1984

In vitro thyrotrophin release with thyrotropin-releasing hormone and an analogue, DN-1417.

Using dispersed and primarily cultured cells of rat pituitary glands, thyrotrophin (TSH) release by TSH-releasing hormone (TRH) and an analogue, gamma-butyrolactone-gamma-carbonyl-L-histidyl-L- prolinamide (DN-1417) which is more potent than TRH on central nervous system behavioural paradigms, was examined under conditions of static incubation and superfusion. Static incubations of the cells with different concentrations of DN-1417 (10(-7)-10(-4) M) and TRH (10(-10)-10(-6) M) resulted in a dose-related increase of TSH release and the response to both peptides, in logarithmic doses, was in parallel. The potency of DN-1417 related to TSH release was 0.14-0.26% that of TRH. Maximal TSH release induced by DN-1417 (10(-5) M) was slightly but significantly greater than that by TRH (10(-7) M). In the presence of 3-isobutyl-1-methylxanthine, the TSH response to either of the peptides was augmented, and the difference in the maximal TSH release by either peptide became insignificant, suggesting that TRH as well as DN-1417 act through the same mechanism of mediation by the cyclic nucleotides. In the superfusion study, a biphasic profile of TSH release was observed during a continuous exposure (100 min) to maximal doses of either the analogue or TRH. The biphasic release of TSH was thought to be specific to TRH action because high K+ produced a different profile of the release. These results indicate that the potency of DN-1417 in TSH release is considerably lower than that of TRH, and also suggest that the direct action of DN-1417 on TSH release is qualitatively similar to that of TRH.

Animals↗