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Biomedical subjects

M Ikeuchi

Publications and source records attributed to M Ikeuchi.

At least 91 records · Page 5Linked to original sources

Phosphorylation of Photosystem II Components, CP43 Apoprotein, D1, D2, and 10 to 11 Kilodalton Protein in Chloroplast Thylakoids of Higher Plants.

Phosphorylated thylakoid proteins of spinach (Spinacia oleracea L.) and pea (Pisum sativum L.) were solubilized, fractionated by sucrose density gradient centrifugation, and analyzed by gel electrophoresis and crossed immunoelectrophoresis to identify the phosphoproteins. It was found that in addition to intense phosphorylation of light-harvesting chlorophyll complex II, four photosystem II components, CP43 apoprotein, D1, D2, and a 10 to 11 kilodalton protein, are substantially phosphorylated in the light. Furthermore, the CP43 apoprotein, D1 and D2 can be resolved into two electrophoretic subspecies, only one of which is phosphorylated. This indicates that only a fraction of the PSII polypeptides is phosphorylated. Finally, analysis of detergent procedures suggests that the 10 to 11 kilodalton phosphoprotein is a peripheral component of the O(2)-evolving PSII reaction center complex.

Journal Article↗

Characterization of O2 evolution by a wheat photosystem II reaction center complex isolated by a simplified method: disjunction of secondary acceptor quinone and enhanced Ca2+ demand.

An O2-evolving photosystem II (PSII) reaction center complex was prepared from wheat by a simple method consisting of octylglucoside solubilization of Triton PSII particles followed by one-step sucrose density gradient centrifugation. The complex contained six species of proteins including the 33-kDa extrinsic protein with the same relative abundance as in the original PSII particles, one cytochrome b559, 4 Mn, and about 40 chlorophyll (Chl) per O2-evolving unit, and evolved O2 at a high rate of 1400-1700 mumol O2/mg Chl/h. O2 evolution by the complex was dependent on acceptor species, showing a hierarchy, ferricyanide greater than dichlorobenzoquinone greater than phenylbenzoquinone greater than dimethylbenzoquinone greater than duroquinone, and insensitive to DCMU, indicative of disjunction of the secondary quinone acceptor of PSII from the electron transport pathway. O2 evolution also showed a marked dependence on Cl- and Ca2+: about 10-fold acceleration by Cl- and an additional 2- to 3-fold by Ca2+. Comparison of the dissociation constants for Cl- and Ca2+ between the complex and NaCl-washed PSII particles revealed that octylglucoside treatment gives rise to a new Ca2+-sensitive site by removal of some unknown factor(s) other than the extrinsic 22- and 16-kDa proteins, while it preserves the Cl(-)-sensitive site as native as in NaCl-washed PSII particles. Analysis of the relationship between Cl- demand and Ca2+ demand revealed that Ca2+ absence noncompetitively inhibits the Cl(-)-supported O2 evolution, indicative of the independence of the binding site of these two factors.

Benzoquinones↗

5'-Nucleotidase activities in human fetus.

Specific 5'-nucleotidase (5'-N) activity in 17 human fetuses was systemically studied in order to get basic values of the enzyme activity. A wide spectrum of 5'-N activity among the organs was revealed. Very strong activity was found in placenta (42.62 +/- 19.24 nmol adenosine/mg protein/min), skeletal muscle (31.80 +/- 11.10) and skin (27.31 +/- 13.00); strong activity in liver (18.96 +/- 7.60), pituitary (15.06 +/- 6.13) and thyroid (12.69 +/- 4.47); moderate activity in lung (8.43 +/- 3.68), pancreas (8.20 +/- 2.26), small intestine (8.07 +/- 2.28), lymph node (7.26 +/- 2.22), thymus (7.06 +/- 2.52), spinal cord (5.86 +/- 1.96) and spleen (5.65 +/- 2.52), and weak activity in testis (4.02 +/- 0.79), heart (3.95 +/- 1.22), adrenal (3.46 +/- 1.68), kidney (3.16 +/- 0.83), ovary (3.16 +/- 0.72), aorta (2.98 +/- 1.20), cerebellar hemisphere (2.28 +/- 1.09) and frontal lobe of the cerebrum (1.49 +/- 0.54). These data are the first to be reported on specific 5'-N activity in the human fetus. The significance of the wide range of 5'-N activity among the organs, and future aspects on the study of 5'-N activity with respect to cell differentiation, maturation, development, aging or malignant transformation were discussed.

5'-Nucleotidase↗

The study of local fibrinolysis in abortion.

The etiology of abortion, which is still a moot question, is now under intense investigation. The present study discussed the possible role of local fibrinolysis (villous tissue fibrinolysis) in the pathogenesis of abortion by studying tissue fibrinolytic activity in tissue culture as well as blood coagulation, fibrinolysis and the kinin system. Subjects studied include: 1) normal villous tissue (n=46), early pregnancy loss, whose fetal cardiac activity had once been identified (n=22) designated as Group A, and Group B whose fetal cardiac activity had never been identified (n=82). The villous tissues were cultured for 24 hours and then the urokinase (UK) inhibition activity in the medium was determined. 2) Threatened abortion resulted in abortion (poor prognosis, n=42) or the pregnancy continued (good prognosis, n=81). In these patients the following substances in plasma were determined: Prekallikrein, alpha 2-plasmin inhibitor, alpha 1-antitrypsin, alpha 2-macroglobulin, C1-inactivator, antithrombin-III, plasminogen, fibrinogen, fibrin degradation products (FDP). The results are: 1) UK inhibition activity (against UK 2.5 iu), normal villous tissue 26.3 +/- 14.6%, Group A 26.0 +/- 10.3%, Group B 9.6 +/- 10.7%, a significant difference between the normal villous tissue and Group B villous tissue was observed. This suggested that the increased villous tissue fibrinolytic activity due to decreased UK inhibition activity may be one of the causes of abortion. 2) Prekallikrein was significantly reduced in patients with abdominal pain. Also, a significant reduction in plasminogen and elevated C1-inactivator was observed in patients with poor prognosis. The significance of these findings was discussed.

Abortion, Threatened↗

[Fundamental and clinical studies on aztreonam in the gynecological field].

Aztreonam (AZT), a new monocyclic beta-lactam antibiotic was studied on clinical efficacy for infectious disease in gynecological field. At about 80 minutes following intravenous injection of 1 g dose of AZT, it penetrated well into internal genital organs at therapeutic levels. Moreover it transferred very fast and enough into intrapelvic dead space exudate, and its level was kept still as high at 12 hours after administration. AZT was given to 20 women affected with gynecological infectious disease. The outcome of AZT therapy was as follows: effective in 5 out of 6 patients (83.3%) administered intravenously and in all of 14 patients (100%) received intramuscularly. Notable adverse effects or abnormal laboratory findings were not observed except 1 case of diarrhea and 2 cases of transient and slight elevation of serum CPK and transaminases. Based on these results, we may conclude that AZT is a highly effective and a very safe antibiotic for the treatment of infectious disease in gynecological field.

Adult↗

Glucagon and forskolin have dual effects upon islet cell electrical activity.

We have investigated the effects of glucagon and forskolin upon pancreatic islet cell electrical activity using intracellular recordings from single mouse islets. Glucagon (0.1-2.0 microM) and forskolin (0.5-5.0 microM), both adenylate cyclase activators, potentiated glucose (200 mg/dl)-induced electrical activity. In the steady-state, islet cells have cyclic electrical activity with periodically recurring "plateau" depolarizations (with superimposed Ca++ action potentials) separated by silent hyperpolarizations. Both glucagon and forskolin mimicked glucose stimulation by increasing the fraction of each cycle spent in the plateau phase (the "plateau fraction"). Unlike glucose, however, glucagon and forskolin increased, rather than decreased, the overall frequency of plateaus, suggesting that plateau frequency is not tightly linked to changes of plateau fraction. This dissociation was also apparent during the onset of drug action. Plateau fraction increased immediately (within one minute), fell to a nadir and then rose to a new steady state level. Plateau frequency, however, rose slowly and monotonically to a new level. Following drug withdrawal plateau fraction returned to control levels several minutes before plateau fraction. From these results it was concluded that cAMP has two effects upon islet cell electrical activity: one is to increase plateau fraction possibly by stimulating glucose-dependent process, which results in increasing in Ca++ influx, and the other to increase plateau frequency possibly by reducing intracellular Ca++ buffering.

Action Potentials↗

Rat islet cells have glucose-dependent periodic electrical activity.

In order to examine whether rat islet cells have a glucose-dependent plateau/silent phase pattern of electrical activity as seen in mouse islets, intracellular recordings were made in cultured whole rat islets. Rat islet cells responded to glucose stimulation with membrane potential alterations between a polarized silent phase and a depolarized plateau phase associated with spikes. Increasing or decreasing glucose stimulation prolonged or shortened the relative duration of plateau phase, respectively. Removal of glucose from the medium caused membrane hyperpolarization with disappearance of electrical activity while reintroduction of glucose caused membrane depolarization and biphasic onset of electrical activity. These results indicate that rat islet cells have a glucose dependent plateau/silent phase electrical mechanism nearly identical to that seen in mouse islets.

Animals↗

In vitro paracrine regulation of islet B-cell function by A and D cells.

In monolayer cultures of islet cells from neonatal rats, incubation of cells for 1 hour with either anti-somatostatin serum or anti-glucagon serum enhanced insulin release. The former appears to be due to neutralization of endogenously secreted somatostatin. The latter may be due to removal of a stimulatory effect of endogenously released glucagon upon somatostatin secretion. Thus, although exogenously added glucagon stimulates insulin secretion, the effect of endogenously released glucagon upon islet B cells is a restraining one which may be mediated through an effect upon D cells and their release of endogenous somatostatin.

Animals↗

[Experimental and clinical studies of cefmenoxime in the field of obstetrics and gynecology].

The study group was organized to evaluate the usefulness of cefmenoxime (CMX) injection, a new synthetic cephalosporin, for the treatment of infections in the field of obstetrics and gynecology. Fundamental and clinical studies were made by the society and the following results were obtained. 1. The peak distribution of CMX's MIC for E. coli, Klebsiella sp., Enterobacter sp., Bacteroides sp. and Peptococcus sp. isolated from obstetrical and gynecological infections with relatively high frequencies area 0.1, less than or equal to 0.05, 0.2, 3.13, 1.56 micrograms/ml, respectively, with an inoculation of 10(6) cells/ml. 2. When 1 g of CMX is administered by intravenous drip infusion for 1 hour, the maximum concentrations in various tissues of female genital organs were as follows: 14.2 and 13.2 micrograms/g in ovary and oviduct, respectively, at 1.20 hours after the start of administration, and 16.9 and 26.3 micrograms/g in corpus uteri and cervix uteri, respectively, after 1 hour. As for the transfer to the exudate in the pelvic dead cavity, the peak concentration was 15.6 micrograms/ml after 2.13 hours. 3. In the clinical studies, CMX was given to 258 cases with female genital organ infections and others. As for the clinical effects, with exclusion of 3 cases in which other antibiotics are concomitantly used, responses were excellent in 76 cases, good in 162 cases and poor in 17 cases, among 255 cases in total. The efficacy rate was 93.3%. The efficacy rates by diseases were 97.1% (68/70) for intrauterine infections, 88.8% (79/89) for intrapelvic infections, 98.4% (62/63) for adnexitis, and 100% (23/23) for infections of external genital organs. As for the clinical effects on causative bacteria, the efficacy rates were 100% (19/19) for single infections due to Gram-positive bacteria, 94.8% (55/58) for single infections due to Gram-negative bacteria, and 88.2% (15/17) for single infections due to anaerobic bacteria. And its efficacy rates were 89.6% (69/77) for mixed infection cases. Side effects were observed in 2 cases (0.8%); 1 case with eruption, and 1 case with diarrhea and vomiting. As for abnormal laboratory findings, lower white blood cell count was observed in 2 cases and elevation of the values regarding hepatic functions in 9 cases. All cases were returned to the normal after the completion of the administration. Cefmenoxime showed a satisfactory clinical efficacy and a potent bacteriological effect in treatment of the infections in the field of obstetrics and gynecology, and it has been concluded that cefmenoxime will be useful addition to the antibiotics for the therapy of these infections.

Adolescent↗

Amylase-producing lung cancer: case report and review of the literature.

A case of hyperamylasemia with lung cancer is described. Macroamylasemia was excluded by a normal amylase/creatinine clearance ratio and by a sedimentation constant obtained by sucrose density gradient centrifugation. Positive immunofluorescent staining of tumor cells with a specific antibody against human salivary amylase and significant amylase activity in the primary tumor and metastases support the hypothesis of independent production of amylase by the lung tumor. Cellulose--acetate membrane electrophoresis demonstrated three bands of amylase activity. The major component corresponded to normal salivary amylase in electrophoretic mobility, isoelectric point and molecular size. The minor bands, one of which occupied about 10% of the total amylase activity in serum, urine and tissue homogenates, demonstrated a lower electrophoretic mobility and a more acidic isoelectric point. Gel filtration and electrophoresis disclosed that these minor bands were derived from an amylase isozyme with a larger molecular size than that of normal salivary amylase. The results suggest ectopic tumor production of heterogenous amylase isozymes, with the larger form being secreted into the circulation.

Adenocarcinoma, Papillary↗

Dual effects of veratridine on glucagon and insulin secretion: dependence upon extracellular and intracellular calcium.

The stimulatory effect of the sodium ionophore, veratridine (10, 25 and 50 microM), on glucagon and insulin secretion was investigated using monolayer cultures of newborn rat pancreas. The results suggest that intracellular accumulation of sodium modulates hormone secretion from both alpha- and beta-cells. The action of veratridine is dependent, at least in part, on the extracellular calcium as its effect was attenuated or lost when extracellular calcium was deleted. Its action was also dependent on intracellular calcium since preincubation of cells in low, normal, or high calcium to diminish, maintain, or increase intracellular calcium, followed by incubation with veratridine in the absence of calcium, altered the secretory responses of both glucagon and insulin. Ouabain (0.5 mM) stimulated glucagon and insulin secretion, although its effect was less than that of veratridine (50 microM). These results suggest that a common releasing mechanism, dependent on extra- and intracellular calcium, is involved in both endocrine cells.

Animals↗

[Transfer of cefotaxime to the pelvic organs (author's transl)].

The new antibiotic cefotaxime (HR 756, CTX) has been proved to be clinically effective against infections observed in the field of obstetrics and gynecology. The present study was intended to investigate the transfer of CTX to the internal genital organs and the dead pelvic space. The results were obtained as follows: 1. The concentrations of CTX transferred to the uteri and its appendages after CTX 1 g intravenous injection were sufficiently effective against the major pathogens (Gram-negative and anaerobic bacteria) demonstrated in the field of obstetrics and gynecology. 2. The concentrations of CTX transferred to the dead space of the pelvis were effective against almost all of the Gram-negative bacteria for 6 to 12 hours after CTX 1 g or 2 g intravenous injection. CTX was thus proved to be very effective for the prevention and treatment of infections of the dead pelvic space.

Cefotaxime↗

Monolayer culture of human fetal and adult pancreas. Static and dynamic studies of insulin release in vitro.

Insulin release from pancreata of human fetuses aged 4 to 9 months and from adult pancreata were studied in monolayer cell culture by static incubation and perifusion technique. Fetal pancreata at the midterm of gestation (4 to 6 months) showed no response of insulin release to glucose. In a case of 9 months-old fetus, in which a small but significant increase of insulin release was observed with glucose (300 mg/ml). Tolbutamide (100 microgram/ml) had no effect on insulin release from all the pancreata of fetuses tested. Caffeine (5 and 10 mM), a phosphodiesterase inhibitor, potentiated insulin release by itself and also induced the glucose-stimulated insulin release from the fetal pancreata in the dose related manner. Glucagon (2 microgram/ml), L-isoproterenol (2 microgram/ml), L-arginine (10 mM) and L-leucine (10 mM) failed to induce any increase of insulin release from fetal pancreata. In the presence of caffeine, the significant increase of insulin release from fetal pancreata was observed with L-leucine, but not with L-arginine. There was no evidence of the maturation of B-cells during the culture periods (4 to 8 days), probably lacking the key steps of stimulus-secretion couplings in relation to adenylate cyclase-cyclic AMP system. By contrast, glucose (100 and 300 mg/100 ml), tolbutamide (100 microgram/ml), L-arginine (10 mM) and caffeine (5 mM) caused a significant increase of insulin release from adult pancreata. Thus, the development of human pancreatic B-cells seems to depend substantially on gestational age, being ready to equip most machinary of insulin release before delivery.

Arginine↗

Isoproterenol-stimulated C-peptide and insulin secretion in diabetic and nonobese normal subjects: decreased hepatic extraction of endogenous insulin in diabetes.

After the iv injection of 2 micrograms isoproterenol, peripheral plasma insulin and C-peptide concentrations were measured in 16 nonobese normal subjects and 53 maturity-onset diabetic subjects. Basal insulin (P < 0.01) and C-peptide (P < 0.05) levels were increased in obese diabetic subjects compared to nonobese normal subjects. Isoproterenol-stimulated insulin (P < 0.01) and C-peptide (P < 0.05) increments were increased in obese diabetic subjects compared to nonobese diabetic subjects. Hepatic insulin extraction, measured by comparing the ratios of insulin increment to C-peptide increment after isoproterenol injection, was decreased in both nonobese and obese diabetics compared to normals (P < 0.05). No significant differences in the ratios were found between nonobese and obese diabetics or between patients on diet or sulfonylurea therapy. Age, sex, duration of disease, familial predisposition to diabetes, and diabetic retinopathy did not influence the ratios. Isoproterenol-stimulated C-peptide increments (P < 0.05) and fasting blood glucose levels (P < 0.05) were decreased in diabetics showing decreased hepatic insulin extraction compared to diabetics with normal hepatic insulin extraction. Isoproterenol-stimulated insulin increments in diabetics showing decreased hepatic insulin extraction were higher than in normals (P < 0.05). These studies indicate that hepatic insulin extraction decreases in nonobese and obese diabetic subjects. It might be postulated that the lesser amount of secreted insulin is able to show biological activities more efficiently in diabetics with decreased hepatic insulin extraction.

Adult↗

The relationship of intracytoplasmic movement of beta granules to insulin release in monolayer-cultured pancreatic beta-cells.

To study the mechanism of insulin release, we examined beta-granule movement in the cytoplasm of monolayer-cultured B-cells. The majority of the granules do not move, while about 2% of the granules moved per minute. The velocities of 90% of the moving granules exceeded 0.4 micrometer/s and showed saltatory type of movement. This movement may have a role in transport of the beta granule from Golgi to B-cell membrane. We studied the mechanism of this movement using colchicine. Granule movement decreased exponentially by treatment with colchicine (10(-6) M to 10(-4) M). Almost 60 min was necessary to get a full inhibitory effect of colchicine on granule movement. Colchicine (10(-8) M to 10(-4) M) inhibited insulin release in a dose-dependent manner. Maximum inhibition of insulin release (by about 40%) by colchicine (10(-4) M) required 60 min. Granule movement also decreased when insulin release was inhibited by lowering glucose from 16.5 mM to 2.7 mM. Thus, granule movement participates in the mechanism of insulin release and may be related to the microtubular system.

Animals↗