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The aging characteristics or broad area InGaAlP visible light laser diodes have been investigated. Asymmetric coatings and a highly p-doped cladding layer were employed. Highly reliable operation, as high as 100 mW for more than 2000 h has been realised at 15 o C

This study was aimed to elucidate whether GDP can mediate hormonal signal to adenylate cyclase in hepatic glucagon sensitive adenylate cyclase with ATP as substrate. Conversion of added GDP to GTP catalyzed by nucleoside diphosphate kinase was suppressed to less than 0.3% of added GDP by including UDP. Inhibition of this enzyme activity by UDP was accompanied by a preferential loss of the stimulatory effect of glucagon plus GDP on cyclase activity without changes in effects of glucagon plus GTP, glucagon plus guanosine 5'-(beta, gamma-imino)triphosphate, and NaF. Under this condition, i.e. in the presence of UDP, GDP competitively inhibited the actions of GTP (Ki for GDP, 1 microM) and guanosine 5'-(beta, gamma-imino)triphosphate in the presence of glucagon, the inhibition being complete at high GDP concentrations. GDP also inhibited cyclase activity stimulated by NaF with UDP but did only slightly without UDP. It was demonstrated that nucleoside diphosphate kinase is located in membranes in addition to cytosol fraction. However, the activity of membrane-associated enzyme was not affected by the addition of glucagon. Based on these observations, it is concluded that GDP is unable to mediate hormonal signal to adenylate cyclase and that it acts as an inhibitor of cyclase activity stimulated by GTP or its analog along with hormone. The results suggest a possible role of membrane-associated nucleoside diphosphate kinase in determining GTP and GDP levels at or near their binding site so as to replenish GTP and, thereby, decrease the inhibitory action of GDP when hormone is present.

Previous studies from this laboratory have proposed that membrane-associated nucleoside diphosphate kinase (m-NDP kinase) may play a role in regulation of adenylate cyclase by channeling GTP, an essential cofactor of adenylate cyclase regulation, into GTP-binding protein (Gs) in a hormone-dependent manner. To understand the true role of m-NDP kinase, in the present study, the m-NDP kinase was solubilized and purified to apparent homogeneity from rat liver purified plasma membranes and characterized in comparison with the cytosolic enzyme purified from the same tissue (s-NDP kinase). Some physical properties determined were: molecular weight (monomer), 18,300; sedimentation coefficient (s20,w), 6.2 S; isoelectric point (pI), 6.0. These values and kinetic parameters of the m-NDP kinase were almost identical to those of the s-NDP kinase whose characteristics were more extensively studied. A peptide mapping study of the 125I-labeled m- and s-NDP kinases gave essentially identical patterns. Polyclonal antibodies against the s-NDP kinase, which also cross-reacted with the m-NDP kinase, were prepared. Immunoblotting studies with the affinity-purified antibodies revealed that the monomer molecular weight of the purified m- and s-NDP kinases was identical to the values of unpurified enzymes present in membranes and crude extract. These results demonstrate that the purified m-NDP kinase underwent no remarkable modification during solubilization and purification, and that the m- and s-NDP kinases are quite similar in protein structure, if at all different. The physiological relevance of the m-NDP kinase in relation to the adenylate cyclase system is discussed.

EDTA-treated microsomes prepared from rat brain mainly consisted of sealed membrane vesicles 200-500 nm in diameter and were rich in both Cl- -ATPase and Na+,K+-ATPase activities. Such Cl- -ATPase-rich membrane vesicles accumulated Cl- in an ATP-dependent and osmotically reactive manner in the presence of 1 nM ouabain. The Cl- uptake was maximally stimulated by ATP with a Km value of 1.5 mM; GTP, ITP, and UTP partially stimulated Cl- uptake, but CTP, beta, gamma-methylene ATP, ADP, and AMP did not. The ATP-dependent Cl- uptake was accelerated by an increase in the medium Cl- concentration with a Km value of 7.4 mM. Such stimulation of Cl- uptake by ATP was dependent on the pH of the medium, with an optimal pH of 7.4, and also on the temperature of the medium, with an optimal range of 37-42 degrees C. Ethacrynic acid dose dependently inhibited the ATP-dependent Cl- uptake with a concentration for half-maximal inhibition at 57 microM. N-ethylmaleimide (0.1 mM) completely inhibited and sodium vanadate (1 mM) partially inhibited the ATP-dependent Cl- uptake. The membrane vesicles did not accumulate H+ in the Cl- uptake assay medium. The ATP-dependent Cl- uptake profile agreed with that of Cl- -ATPase activity reported previously (Inagaki, C., Tanaka, T., Hara, M., and Ishiko, J. (1985) Biochem. Pharmacol. 34, 1705-1712), and this strongly supports the idea that Cl- -ATPase in the brain actively transports Cl-.

A radioimmunoassay system has been developed for the measurement of two major metabolites of 9,3"-diacetylmidecamycin, Mb-6 and Mb-12. A radioimmunoassay for Mb-6 was performed by using anti-Mb-6 serum and a [125I]tyramined Mb-6 derivative as a radiolabeled antigen. The labeled antigen was prepared by the chloramine T method. The antiserum was obtained from a rabbit immunized with Mb-6 conjugated to bovine serum albumin. The obtained antiserum was cross-reactive with two other metabolites of 9,3"-diacetylmidecamycin, Mb-2 and Mb-12, in addition to Mb-6. This Mb-6 radioimmunoassay system could detect Mb-6 concentrations as low as 100 pg/ml of serum. The coefficients of variation were 4.5% (intra-assay) and 5.1% (inter-assay). A radioimmunoassay for Mb-12, using anti-midecamycin serum and a [125I]tyramined-Mb-12 derivative, has also been developed. The antiserum was cross-reactive only with Mb-12 among the 9,3"-diacetylmidecamycin metabolites. This Mb-12 radioimmunoassay system could detect Mb-12 concentrations as low as 2 ng/ml. The intra- and inter-assay variances were 5.9 and 5.8%, respectively.

A novel nucleoside with an oxetanosyl-N-glycoside has been recently isolated from a culture filtrate from Bacillus megaterium and named oxetanocin A (N. Shimada, S. Hasegawa, T. Harada, T. Tomisawa, A. Fujii, and T. Takita, J. Antibiot. 39:1623-1625, 1986). In this study, we evaluated the antiherpesvirus activity of oxetanocin A and its derivatives and found that 9-(2-deoxy-2-hydroxymethyl-beta-D-erythro-oxetanosyl)guanine (OXT-G) was very potent and selective in inhibiting the replication of human cytomegalovirus (HCMV) in vitro. The median effective concentration for HCMV strain AD169 was 1.0 microgram/ml, and that for herpes simplex virus type 2 strain 186 was 3.5 micrograms/ml. The selectivity index, based on the ratio of the median inhibitory concentration for cell growth of human diploid fibroblasts to the median effective concentration for HCMV plaque formation, was more than 300. The synthesis of HCMV-induced late polypeptides such as the 150,000-molecular-weight capsid and the 68,000-molecular-weight major matrix proteins was strongly suppressed when OXT-G (5 micrograms/ml) was added to the cultures at the beginning of infection. At this concentration of OXT-G, the amount of HCMV DNA detected in the drug-treated infected cells was less than 1/10 of that detected in the infected control cells. The results suggest that the mode of action of OXT-G is inhibition of viral replication by impairing the viral DNA synthesis.

SummaryIsolation of adenylate cyclase-enriched membranes from human platelets was attempted using glycerol lysis technique followed by ultracentrifugation on discontinuous sucrose gradients composed of 24, 30, 34, 37, and 41% (w/w). Adenylate cyclase activity was enriched 4-fold in sample/24% sucrose interface, 7-fold in 24%/30% sucrose interface, and 4-fold in 30%/ 34% sucrose interface fractions with the recovery of 15-20% of the total activity. The enrichment and subcellular distribution of adenylate cyclase resembled in general those of phosphodiesterase and acid phosphatase with slight differences in each other. Protein profiles from SDS-polyacrylamide gel electrophoresis showed that the heavy chain of myosin (Mr = 200,000) was enriched in sample/24% sucrose interface and lower molecular weight proteins in 34%/37% sucrose interface and pellet. The interface fractions between 24 and 34% sucrose were, therefore, collected as adenylate cyclase-enriched membranes.Adenylate cyclase associated with the membranes displayed high specific activity (0.1 and 1-2 nmol/min/mg protein in the absence and presence of stimulants, respectively), and possessed sensitivities to prostaglandins (E1, I2, and D2) as well as cholera toxin. Activation of adenylate cyclase by these compounds required added GTP, indicating that the contamination of the membrane preparations with GTP-like substance (s) was minimal, if at all present.

The authors present two cases of transient occlusion of the major cerebral arteries which occurred during transfemoral catheterization of the carotid artery. Right hemiplegia and aphasia developed suddenly in both cases, and disappeared completely within 14 hours in one case and 25 minutes in the other. On the angiograms performed at the moment of onset of the symptoms, the site of the occlusion was the left internal carotid artery in one case and the left middle cerebral artery in the other. Angiograms which were repeated soon after clinical improvement revealed complete dissolution of the occluding emboli. These cases present direct radiographic evidence that embolic occlusion of a major cerebral artery and its disappearance is the mechanism of the transient manifestation of the neurological deficits associated with cerebrovascular catheterization.

A case of leiomyoma arising from the upper calix of the renal pelvis in a 47-year-old woman is presented. We believe this to be the fourth reported case in the literature.

Oxetanocin is a novel nucleoside containing a 4-membered sugar, oxetanosyl-N-glycoside, and adenine. The effects of oxetanocin and related compounds on the infectivity of human immunodeficiency virus (HIV) were examined. They inhibited HIV infectivity in vitro. Allopurinol and mycophenolic acid produced additive anti-HIV effects when added with these compounds.

Spontaneous abortion in the early stage of pregnancy is now linked to increased prostaglandin (PG) in blood. It has been known for some time that pregnant women's blood content of PG increases at the onset of labor. PGE2 and PGF2alpha have been used to induce labor during the last trimester. Lately PG is sometimes used to induce artificial abortion during the 2nd trimester. According to a study conducted by Dr. Kunimoto of Iwate School of Medicine, there is correlation between greatly increased PG and cramps felt by spontaneous abortion candidates during the 1st trimester. Theoretically, therefore, it is possible to prevent miscarriages in the early stage by administering antagonistic medication such as indomethacin. The antagonistic effect of indomethacin is confirmed but its side effect on the circulatory organs of the fetus still needs to be investigated.