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Biomedical subjects

M Arai

Publications and source records attributed to M Arai.

At least 469 records · Page 26Linked to original sources
PubMed1991

Two distinct steps for spontaneous generation of subprotoplasts from a disintegrated bryopsis cell.

The unusual nature of protoplasm to generate subprotoplasts spontaneously from disintegrated Bryopsis cells was examined. Protoplasm extruded from algal cells aggregated rapidly in cell sap which was derived mainly from huge central vacuoles of the cells. Electron microscopic observations revealed extensive agglutination of algal cellular membranes in the protoplasmic masses, suggesting that this is of primary importance for the wound-healing ability of the alga. Seawater caused spheration of the resultant protoplasmic aggregates. Gelatinous sheaths were formed temporarily surrounding the spherical protoplasmic masses before reformation of cell membrane. Staining with phosphotungstic and chromic acids suggested that new cell membrane was formed by fusion of the disintegrated original cell membrane with cytoplasmic vesicles on the surfaces of the protoplasmic masses. Both pH and salts were found to be essentially important at the two steps of subprotoplast generation. The newly formed cell membranes were responsible for subsequent notable plasmolysis of the wounded cells in seawater. Thus, it is suggested that unicellular marine algae Bryopsis spp. naturally contain effective materials for agglutinating and fusing particular cellular membranes through the sequential aid of acidic cell sap and alkaline seawater after disintegration of the giant cells.

Journal Article↗
PubMed1991

Effect of thyroid hormone on the expression of mRNA encoding sarcoplasmic reticulum proteins.

The purpose of this study was to determine the expression of genes encoding various sarcoplasmic reticulum components that are functionally coupled with calcium release, uptake, and storage function during cardiac hypertrophy induced by thyroid hormone. Hyperthyroidism was induced in two groups of rabbits by the injection of 200 micrograms/kg L-thyroxine (T4) daily for 4 days (T4-4-day group) and 8 days (T4-8-day group). Hypothyroidism was induced in another group of rabbits by adding 0.8 mg/ml propylthiouracil to the drinking water for 4 weeks. The relative expression level of mRNA encoding different sarcoplasmic reticulum proteins was determined by RNA slot blot and Northern blot analysis. In hyperthyroid hearts, the steady-state level of cardiac ryanodine receptor mRNA and sarcoplasmic reticulum cardiac/slow-twitch Ca(2+)-ATPase mRNA were both increased to 147% (T4-4-day group) and 186% (T4-8-day group) of control, respectively, but decreased to 71% and 75%, respectively, in hypothyroid ventricles. The mRNA level for phospholamban was decreased in both hyperthyroidism (T4-8-day group, 72%) and hypothyroidism (77%) in these hearts. On the other hand, calsequestrin mRNA levels did not change in hyperthyroid and hypothyroid ventricles. In accord with the changes in Ca(2+)-ATPase mRNA levels, the Ca(2+)-ATPase protein was increased to 199% (T4-8-day group) in hyperthyroid ventricles and decreased to 86% of control in hypothyroid ventricles. The expression levels of ryanodine receptor, Ca(2+)-ATPase, phospholamban, and calsequestrin mRNAs were similarly altered in skeletal muscle tissues from hyperthyroid and hypothyroid rabbits. These results indicate that the mRNA levels of sarcoplasmic reticulum proteins responsible for calcium release and calcium uptake are coordinately regulated in response to changes in thyroid hormone level in both heart and skeletal muscle. These changes in mRNA level should lead to changes in protein levels and thus to altered calcium release and uptake in the chronic stages of hyperthyroidism and hypothyroidism.

Animals↗
PubMed1991

Identification and characterization of basic fibroblast growth factor in porcine thyroids.

Fibroblast growth factor (FGF) is one of the most potent endothelial cell growth factors and has been found in almost all tissues in the body. However, there is no definitive report showing that FGF exists in the thyroid. In this report, we describe heparin binding endothelial cell growth factor activity in porcine thyroids. The extract from normal adult porcine thyroids was loaded onto a heparin-sepharose affinity column. The mitogenic activity on endothelial cells was found to elute from the column with 0.9 M-2.0 M NaCl. Polyacrylamide gel electrophoresis and an immunoblotting of bioactive fractions showed the basic FGF immunoreactivity in a double band with a molecular weight of 18K and 20K. These results strongly imply that the adult porcine thyroid-derived heparin binding endothelial cell growth factor may be authentic basic FGF and one of its high molecular weight forms. In support of this conclusion, basic FGF mRNA was detected in poly A+ RNA isolated from cultured porcine thyroid cells. On the other hand, recombinant human basic FGF at the concentration of 0.1-10 ng/ml increased the incorporation of 3H-thymidine into FRTL-5 cells and porcine thyroid follicular cells in culture. The stimulatory effects were also observed when the biologically active fractions of heparin-sepharose column of the thyroid extract were added to the culture. In addition, both recombinant human basic FGF at 10 ng/ml and heparin binding fractions from porcine thyroids inhibited TSH-induced iodide uptake by porcine thyroid cells in culture. These results suggest that basic FGF may be one of the important local modulators of thyroid function, cell growth, and angiogenesis.

Animals↗
PubMed1991

Activation of the pituitary-adrenocortical axis in day-old rats by insulin-induced hypoglycemia.

Most newborn mammals, including humans, are susceptible to neonatal hypoglycemia shortly after birth, especially if fasted. Glycogenolysis provides short term benefit, but gluconeogenesis is required for glucose homeostasis at this stage of development. A functional hypothalamic-pituitary-adrenocortical (HPA) axis is essential for glucose homeostasis in adults, but little is known of the importance of this endocrine axis in this regard during the neonatal period. The neonatal rat is an excellent model for study of both glucose metabolism and the HPA, and shares many similarities with other mammals. For the first 2 weeks of postnatal life, the rat HPA appears to be relatively unresponsive to stress, however, which would seem maladaptive during the critical first 24 h. The present study examined the ability of day-old rats to respond to hypoglycemia with activation of the HPA system. Each of three doses of insulin resulted in hypoglycemia (glucose, less than 40 mg/dl), with the greatest decrease in glucose 120 min after an insulin dose of 2.5 U/kg BW. At this dose, plasma corticosterone was increased to levels comparable to those observed in adults. The steroid response was associated with a small but significant increase in ACTH, and both endocrine responses were delayed compared to those in adults. There was no difference in adrenal response time to ACTH in incubations of adrenal cells isolated from day-old or adult rats, however. The stimulatory effect of insulin was progressively diminished in older animals (2-6 days postnatal). Insulin had no direct effect on adrenal steroidogenesis either alone or in combination with ACTH when tested on dispersed cells in vitro. We conclude that 1) the adrenal gland is very sensitive to the stress of hypoglycemia for 1 day after birth, but rapidly declines in activity over the first 6 days of life; 2) the response time of the HPA axis to hypoglycemia stress is delayed in day-old rats, and this delay occurs above the level of the adrenal; and 3) there may be factors in addition to ACTH that promote steroidogenesis on the first postnatal day, or there may be bioactive or immunoreactive differences in the ACTH molecule during this time.

Adrenal Cortex↗
PubMed1991

Effects of retinoids on iodine metabolism, thyroid peroxidase gene expression, and deoxyribonucleic acid synthesis in porcine thyroid cells in culture.

Effects of retinoids on DNA synthesis, iodine metabolism, and thyroid peroxidase messenger RNA levels were studied in cultured porcine thyroid cells. Retinol (10(-8)-10(-5) M) alone did not affect DNA synthesis but potentiated that induced by epidermal growth factor or insulin-like growth factor-I without changes in the number or affinity of receptors for the growth factors, suggesting that retinol stimulates postreceptor events responsible for DNA synthesis. Retinol was an inhibitor of TSH-stimulated iodine metabolism. Iodide uptake and release of organified iodine stimulated by TSH or forskolin were inhibited dose dependently by treatment with retinol. The inhibition was detected at 10(-8) M and was approximately 50% at 10(-6) M. The potency of retinoic acid was comparable to that of retinol. The inhibitory effect of retinol was detected after treatments of thyroid cells for 24 h, and the maximal effect occurred after 48 h incubation. The cAMP accumulation in cultures treated with TSH plus retinol was lower than that of control cultures treated with TSH alone. However, iodide uptake stimulated by 8-bromo-cAMP was also inhibited by retinoids. Retinol reduced TSH- or 8-bromo-cAMP-stimulated gene expression of thyroid peroxidase. Thus, the data suggest that retinoids inhibit TSH-stimulated iodine metabolism by reducing cAMP accumulation and also by acting on the steps subsequent to cAMP production.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1991

Effect of HEBP (1-hydroxyethylidene-1,1-bisphosphonate) on experimental osteoporosis induced by ovariectomy in rats.

The present study was undertaken to test whether long term administration of HEBP could prevent the progress of bone loss induced by ovariectomy in rats. Administration of HEBP was started from day 111 after ovariectomy. The animals received subcutaneous injections of HEBP, at a dose of 0, 2, 4, or 8 mg/kg, every other day for 92 days. Tibiae, femora and incisor teeth were investigated by chemical analyses and by contact microradiography. Effects on calcium, phosphorus, and alkaline phosphatase activity in the plasma were also examined. Progress in the loss of bone density and ash content caused by ovariectomy was prevented by the administration of 2 mg/kg HEBP for 92 days and was partially prevented by the administration of 4 mg/kg. At a dose of 8 mg/kg, however, HEBP did not prevent the bone loss but, rather, potentiated it. These chemical findings were qualitatively confirmed by contact microradiography. A dose-dependent inhibition was observed in the mineralization of incisor dentin. These results suggest that HEBP, at least at low dose levels in which the inhibition of mineralization is not predominant, has a potency to prevent the progress of bone loss induced by ovariectomy. At higher doses, however, this compound seems not to be effective, because of the severe inhibition of mineralization.

Animals↗
PubMed1991

Improvement of postoperative hypocalcemia by repeated allotransplantation of parathyroid tissue without anti-rejection therapy.

Long lasting postoperative hypocalcemia, an uncomfortable complication of a thyroid operation for hyperthyroidism, was treated with allotransplantation of parathyroid tissue. Small pieces of the parathyroid tissue offered from two unrelated donors were transplanted to an 18-year-old male with severe postoperative hypoparathyroidism. Prednisolone was given for 2 days, but no other immunosuppressive drugs were used. The remaining tissue was stored in frozen for the repeat transplantation. The functional activity of the frozen tissue was determined by the production of parathyroid hormone in the tissue culture medium adjusted to appropriate concentration of calcium. Loss of the graft function, probably due to rejection, was supplemented with repeated grafting. Hypocalcemia was improved by three times of transplantation using frozen tissue (once) and fresh tissue (twice). This preliminary trial demonstrates that the tissue transplantation of the parathyroid gland is effective to lessen the symptoms and medication of postoperative hypoparathyroidism.

Adolescent↗
PubMed1991

[The diagnostic value of Tc-99m PYP, Tl-201 dual isotope SPECT to predict the viability of damaged myocardium in the acute phase of myocardial infarction--comparison with stress, delayed, and reinjected Tl-201 SPECT].

To assess the diagnostic value of Tc-99m PYP, Tl-201 dual isotope SPECT for the evaluation of myocardial viability, segmental comparison between dual isotope SPECT and exercise, delayed, and reinjected Tl study were performed with 18 AMI patients. Among 72 damaged myocardial segments, 48 segments (67%) were judged as viable by chronic phase Tl studies. The segments with severely reduced Tl uptake by dual SPECT showed significantly lower prevalence of viable myocardium than the segments with reduced and normal Tl uptake (p less than 0.001). The segments with PYP accumulation localized to the subendocardium represented the favorable outcome compared with the transmural accumulation (p less than 0.001). And overlap segments show better prognosis than the segments without overlap (p less than 0.05). Most importantly, we can get better predictive accuracy of myocardial scar by dual isotope SPECT than the judgement by Tl or PYP SPECT alone (83.3% vs 77.8%, 68.1%). Thus, we conclude that Tc-99m PYP, Tl-201 dual isotope SPECT is useful to assess the severity of myocardial damage in the acute phase of myocardial infarction.

Adult↗
PubMed1991

[Evaluation of an enzyme immunoassay for plasma thrombomodulin].

Thrombomodulin (TM) is an endothelial cell membrane glycoprotein which neutralizes thrombin clotting activity and accelerates thrombin-catalyzed activation of plasma protein C. Its role is considered to be very important to prevent thrombosis. Recently, TM has been found in circulating blood and the roles and the functions have been investigated. In this study, we evaluated the reliance and the clinical usefulness of a TM-measuring-kit by enzyme immunoassay (MGC-01-001: Mitsubishi Gas chemical company). Intraassay reproducibility test, dilution linearity test and in vitro recovery test was obtained satisfactory results. A correlation between plasma and serum on TM levels of healthy individuals was very good and the difference between them was not significant. Normal value of plasma TM levels was instituted 15.73 +/- 6.98 ng/ml by measuring 52 healthy adults. The difference between male and female was not significant. Plasma TM levels did not change significantly after venous occlusion test and on circadian fluctuation. Plasma TM levels in patients with occlusion test and on circadian fluctuation. Plasma TM levels in patients with disseminated intravascular coagulation (DIC) was 40.15 +/- 22.68 ng/ml (mean +/- SD, n = 14). It is significantly higher than the levels in healthy adults. However, the levels in patients with angina pectoris, acute myocardial infarction and aortic aneurysm were not significantly different from those of healthy adults. These findings suggest that the precision of this TM-measuring-kit is satisfactory and the measurement of plasma TM can be useful to diagnose of DIC.

Adult↗
PubMed1991

[A case of severe summer-type hypersensitivity pneumonitis treated with high-dose administration of steroid].

A 40-year-old man who lived in a wooden house built 30 years ago presented with complaints of fever, dry cough and dyspnea. Chest X-ray findings showed interstitial shadows throughout bilateral lung fields. After admission, high-dose administration of 3000 mg of methylprednisolone was performed because of deterioration of chest X-ray shadows and symptoms. In a week, clinical data and symptoms improved. Findings of BAL fluid on admission revealed a relative increase of lymphocytes, neutrophils and mast cells, and pathological findings of transbronchial lung biopsy revealed non-caseous granulation and alveolitis. Precipitating antibodies and indirect fluorescent antibodies against Trichosporon cutaneum and Cryptococcus neoformans had positive reactions and T. cutaneum was isolated and identified from the patient's house. A diagnosis of summer-type hypersensitivity pneumonitis was made according to the criteria advocated by Ando et al. This seemed to be a rare case of summer-type hypersensitivity pneumonitis prolonged after isolation from his normal living environment, successfully treated by high-dose administration of steroid.

Adult↗
PubMed1991

Lamellar scleral resection enhances subretinal fluid absorption in eyes with choroidal congestion.

The effects of choroidal congestion and lamellar scleral resection on the absorption of subretinal fluid were studied in rabbit eyes. Small retinal detachments were induced and choroidal congestion was produced by ligating two vortex veins. Absorption time was prolonged in these eyes to roughly 138% of that in the control eyes. The choroidal congestion could be alleviated by partial thickness scleral resection, after which the absorption time was only 115% of that in untreated eyes. Our data suggest that lamellar scleral resection relieves elevated choroidal tissue pressure and helps to absorb the subretinal fluid.

Absorption↗
PubMed1991

DNA diagnosis of falciparum malaria.

We have developed DNA diagnosis using Universal probe system for the rapid detection of Plasmodium falciparum parasite in blood. We chose the DHFR-TS (dihydrofolate reductase-thymidylate synthase) gene as target for detection which are the junction part (410 bp) of and the DHFR part (790 bp). In the parasite, there is only one copy of target sequence, therefore, the target sequences were amplified by PCR (polymerase chain reaction) to increase the sensitivity. Our hybridization method consists of two probes; a primary probe prepared from a chimeric phage-plasmid vector (pUCf1) containing sequence complementary to the target, and a biotin-labeled secondary probe complementary to a portion of the primary probe, which is detected by the BCIP/NBT method. We showed that the 410 bp was more sensitive than the 790 bp as a target of P. falciparum, and the limit of detection was 10(3) parasites in 1 ml human blood using 410 bp junction part. We also constructed double PCR systems using junction part of DHFR-TS gene. By amplification of the 410 bp of the junction part and reamplification of 228 bp of inside sequence of the 410 bp, as little as 10 parasites in 10 microliters human blood was sufficient for specific detection.

Animals↗
PubMed1991

[Differentiation between fibrin degradation products and fibrinogen degradation products by using newly developed ELISAs].

We should distinguish fibrin degradation products (FbDP) from fibrinogen degradation products (FgDP) in order to analyze fibrinolysis in vivo. We analyzed some disorders associated with hyperfibrinolytic states using ELISA for FbDP, FgDP and total fibrin (ogen) degradation products (TDP) (ORGANON TEKNIKA). Each ELISA was useful in terms of reproducibility and dilution linearity of plasma samples. There was no cross-reaction between FbDP and FgDP. The FgDP/FbDP ratio in normal individuals was 1.65. In patients with DIC, it was 0.43, with FgDP level being increased. These results suggest that fibrinolysis is enhanced in patients with DIC, but it is accompanied by fibrinogenolysis. On the other hand, the FgDP/FbDP ratio in patients given urokinase (UK) was 2.88. This suggests that fibrinogenolysis is enhanced in them. In our study, the FgDP/FbDP ratio increased as DIC improved. Thus, we can regard this as an index of therapeutic effects in patients with DIC. We conclude that these three ELISA are useful in analyzing disorders associated with hyperfibrinolytic states.

Disseminated Intravascular Coagulation↗
PubMed1991

[Expression of human epidermal growth factor and DNA ploidy pattern in gastric carcinoma].

Expression of human epidermal growth factor (EGF) was examined immunohistologically in 93 surgically resected gastric carcinomas, using Biotin-StreptAvidin method pretreated by protease, and its relation with cancer progression and DNA ploidy pattern was studied. DNA ploidy pattern was determined by cytofluorometric measurement. The gastric cancers were divided into two basic ploidy patterns; a diploid mode and an aneuploid mode. EGF expressions were found in 5 out of 20 cases (25%) in intramucosal carcinomas and, the more deeply the carcinomas invaded into the gastric wall, the greater the frequency of EGF expressions did not always become. In the carcinomas with the aneuploid pattern, EGF expression was found only in 2 out of 12 cases (17%) in early cancers and significantly increased in advanced cancers, 15 out of 22 cases (68%). On the other hand, in the carcinomas with the diploid pattern, EGF was expressed in 9 out of 31 cases (29%) in advanced cancers, not significantly different in early cancers, 11 out of 28 cases (39%). Consequently, in advanced cancers, EGF was found more frequently in the aneuploid tumors than in the diploid tumors. These results suggested that EGF expression in the gastric carcinomas is closely correlated with the progression to the advanced cancer with DNA aneuploidy.

Aged↗
PubMed1990

Quantitative analysis of serum IL-6 and its correlation with increased levels of serum IL-2R in HIV-induced diseases.

We have devised a luminescence sandwich ELISA for the quantification of IL-6 in both sera and cell culture supernatants, which had a detection limit of 100 fg/ml of test sample. By using the luminescence sandwich-ELISA, low but measurable levels of IL-6 (9.5 pg/ml on average) were found in the sera from normal individuals. The serum levels of IL-6 were elevated in HIV-seropositive asymptomatic carriers (55.5 pg/ml on average), and the IL-6 levels were correlated with the degree of HIV-induced disease progression (AIDS-related complex 106.8 pg/ml on average and (AIDS 283 pg/ml). IL-6 immunoreactivity in the sera of AIDS patients eluted at a 25,000 m.w. major peak, which was biologically active and heat-stable, and a 500,000 m.w. minor peak in size-exclusion HPLC. Interestingly, a significant correlation was observed between the serum IL-6 levels and soluble IL-2R levels. In vitro, HIV infection of PHA-activated PBMC led to enhanced release of IL-6 into the culture supernatants. Moreover, soluble IL-2R release was markedly increased by adding exogenous IL-6, whereas it was decreased by adding the neutralizing anti-IL-6 mAb to the cultures. These results demonstrate that increased IL-6 levels are significantly associated with sIL-2R levels, and suggest a cause of the increased levels of this receptor in patients with HIV infection. Furthermore, both serum IL-6 and serum IL-2R levels in HIV infection reflect the stage of the HIV-induced disease.

Cells, Cultured↗