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H Ohshika

Publications and source records attributed to H Ohshika.

At least 73 records · Page 4Linked to original sources
PubMed1994

[Recent advances in immunological diagnosis for tuberculosis].

Recent advances in immunological diagnosis for tuberculosis including tuberculin Mantoux test and serodiagnosis were reviewed. New tuberculins (T1327, T1456) were reported to be more specific than the conventional one (RT23). Tuberculins from atypical mycobacteria (PPD-B, PPD-Y, PPD-F) were reported as a useful tool for the diagnosis of atypical mycobacteriosis. Optical density index method is a most appropriate method for a clinical use among several methods for the expression of antigen titer in serodiagnosis using ELISA. The duration of disease is important for understanding the results. IgM antibody rises in the early stage of the disease and comes down in 10 weeks after onset, while IgG antibody rises lately. Anti-cord factor antibody is a highly specific antibody for tuberculosis and may be a potent candidate for a clinical diagnostic tool. Anti-PPD-B antibody was elevated in atypical mycobacteriosis and pulmonary tuberculosis also. The ratio of anti-PPD-B antibody to anti-PPDs antibody was elevated in atypical mycobacteriosis while it was lowered in pulmonary tuberculosis. It may be helpful for suggesting the causative organism when the sputum smear is positive. The opposite results have been reported on the serodiagnosis in HIV infection. The usefulness of serodiagnosis for tuberculosis in HIV infected patients remained controversial.

Antibodies, Bacterial↗
PubMed1994

Effects of ethanol on the function of G proteins in rat cerebral cortex membranes.

The acute effects of ethanol on the function of G protein in rat cerebral cortical membranes were examined using immunoblotting and photosensitive GTP labeling. Ethanol potentiated GppNHp-dependent activation of adenylyl cyclase and inhibition of forskolin-stimulated activity of the enzyme in corticol membranes from Wistar rats. It also enhanced guanine nucleotide binding to Gs and Gi as estimated by photoaffinity labeling. However, ethanol had no effects on the contents of Gs/alpha, Gi(1) alpha and Gi(2) alpha, and G beta subunits. While it potentiated Gi-mediated inhibition of adenylyl cyclase in Wistar rats, ethanol had no effect on the inhibitory regulation of the enzyme in the membranes from Fischer 344 rats. These results suggest that ethanol in vitro enhances both Gs and Gi functions in cerebral cortical membranes from Wistar rats and that the Gi function in the cerebral cortex may be differentially regulated by ethanol in Wistar and Fischer 344 rats.

Adenylyl Cyclases↗
PubMed1994

Reduced sensitivity to ethanol of Gs alpha and Gi/o alpha in the cerebral cortex of alcoholic patients.

In this study, we examined the quantity and quality of G proteins in membrane preparations from cortical regions (frontal, parietal, temporal and occipital cortex) in post-mortem brains obtained from subjects with chronic alcoholism and controls matched with respect to age and post-mortem delay (PMDT). Immunoblot analysis showed that the level of GsH alpha (52 kDa) was significantly decreased in temporal cortical membranes from alcoholics compared with controls, while no differences were observed in the amount of any G protein in frontal, parietal and occipital regions. Additionally, ethanol enhanced photoaffinity guanine nucleotide binding to both G alpha and Gi/o alpha in human cortical membranes. The percentage of increase in ethanol-stimulated photoaffinity GTP labeling of Gs alpha and Gi/o alpha was decreased in alcoholic patients in all cortical regions. These observations indicated that subsensitivities to ethanol-induced stimulation in G protein may contribute to impaired trans-signaling in cortical membranes of chronic alcoholics.

Alcoholism↗
PubMed1993

Adrenoceptor coupling mechanisms which regulate salivary secretion during aging.

In parotid slices and membranes from Wistar rats 2, 12 and 24 months old, changes are noted in adrenoceptor-stimulated K+ fluxes, formation of [3H]inositol phosphates ([3H]IPs), cAMP production, and membrane environment. Norepinephrine-stimulated K+ efflux and formation of [3H]IPs in the slices proceed through an alpha 1-adrenergic mechanism and are reduced 20% and 40% during aging, respectively. In beta-adrenoceptor stimulation with isoproterenol, no age changes were observed in K+ influx and cAMP production. The cholesterol content in membranes was reduced with age; concomitantly, the membrane viscosity decreased with age. These results indicate that the alterations in the membrane environment may provide age-dependent modulation of alpha 1-adrenoceptor coupling mechanisms and their functions.

Aging↗
PubMed1993

Alpha 1-adrenoceptors in neonatal rat cardiac myocytes: hypoxia alters the responsiveness of alpha 1A and alpha 1B subtypes.

We investigated the contribution of alpha 1-adrenoceptor subtypes to the chronotropic response to norepinephrine (NE) in cultured neonatal rat cardiac myocytes under normoxia and hypoxia. A dose-dependent negative chronotropic response was induced by NE in the presence of propranolol. Hypoxic exposure inverted the negative chronotropic response to NE to a positive one. All of these chronotropic responses were completely antagonized by prazosin. In normoxic conditions, the NE-induced negative chronotropic response was completely antagonized by WB4101 but only partially (55%) so by chloroethylclonidine (CEC). After hypoxic exposure, WB4101 partially antagonized the positive chronotropic response to NE (54%), while CEC completely suppressed the action of NE. Hypoxic exposure did not alter the number of alpha 1A- and alpha 1B-adrenoceptor subtypes as measured by [3H]prazosin binding following CEC treatment. These results indicate (1) that cultured neonatal rat cardiac myocytes contain both alpha 1-adrenoceptor subtypes, i.e., alpha 1A and alpha 1B, and (2) that the predominant alpha 1-adrenoceptor subtypes mediating NE-induced chronotropy were altered by hypoxia.

Animals↗
PubMed1993

Down-regulation of beta-adrenoceptors and loss of Gs alpha subunit levels in ventricular myocardium of rats treated with isoproterenol.

We investigated the influence of chronic beta-adrenergic stimulation on the beta-adrenoceptor-G protein-adenylyl cyclase system in rat ventricular myocardium. The rats received twice-daily injections of 4 mg/kg isoproterenol (ISO) alone or with 8 mg/kg propranolol (PROP) for 4 days. The ISO (10 microM)-induced increase in tissue cAMP production was lower (50%) after chronic ISO treatment than in control myocardium. The beta-adrenoceptor density decreased by 43% in ventricular membranes from ISO-treated rats. Immunoblotting techniques using specific antibodies against G proteins revealed that ventricular myocardium contains three Gs alpha subunit isoforms of 45, 47 and 52kDa. ISO treatment decreased levels of the three Gs alpha subunits by a total of 40%, while no change in Gi alpha (40/41kDa) and Gcommon beta (35/36kDa) levels were found in the same membrane preparations. The antagonist PROP almost totally blocked the effects of ISO treatment on cAMP, beta-adrenoceptors and Gs alpha subunits. These results suggest that chronic beta-adrenergic stimulation causes not only down-regulation of beta-adrenoceptors, but also loss of Gs alpha subunit levels in rat ventricular myocardium.

Animals↗
PubMed1993

Characterization of alpha 1-adrenoceptors which mediate chronotropy in neonatal rat cardiac myocytes.

1. In the present study, we investigated the effect of culture on alpha 1-adrenoceptors that mediate chronotropy and on alpha 1-adrenergic signal transduction in neonatal rat cardiac myocytes. 2. The spontaneous beating rate of neonatal rat myocytes after 3 or 7 days in culture was 37.4 +/- 4.2 or 102.0 +/- 4.3 beats min-1, respectively. The alpha 1-adrenoceptor-mediated chronotropic effect of norepinephrine was positive at day 3 of culture. In contrast to day 3 of culture, the neonatal myocytes exhibited a negative chronotropic response to norepinephrine on day 7 of culture. Both of these effects of norepinephrine were completely abolished by prazosin. 3. The affinity (Kd) and/or density (Bmax) of alpha 1-adrenoceptors labeled with [3H]prazosin in membranes from cultured myocytes were not significantly different between day 3 and day 7 of culture. 4. The expression of Gs, Gi, Gq and Go alpha-subunits in membranes from cultured myocytes was found to be significantly increased with the passage of culture time by immunoblot analysis. In contrast, no significant differences in G beta-subunit expression were observed between day 3 and day 7 of culture. 5. Norepinephrine-stimulated inositol 1,4,5-trisphosphate production by radio-binding protein in neonatal myocytes after 7 days of culture was significantly higher than that of the day 3 counterpart. 6. No significant changes in phospholipid and cholesterol contents in membranes from neonatal myocytes were observed with longer culture times.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

[Application of a Fotonic Sensor for measurement of chronotropy and contractility in cultured rat cardiac myocytes].

We used a Fotonic Sensor, a fiber optic displacement measurement instrument, to measure the chronotropy and the contractility of cultured neonatal rat cardiac myocytes. The principle of the measurement is to detect changes in the distance between the probe and myocytes vertically extruded by the contraction. A fiber optic probe consists of adjacent pairs of light-transmitting and light-receiving fibers. The ratio of reflected light to transmitted light changes proportionally to the distance between the probe and an object at a certain range shown in a calibration curve. The analogue output from the sensor was transferred to a personal computer through an analogue/digital converter and analyzed. The sensor was able to detect the rate of myocyte beating, i.e., chronotropy, with a high correlation to the frequency of electrically stimulated beating and agreed well with the beating rate counted visually under a microscope. The contractility was evaluated by the maximum contraction velocity (Vm) by the first derivatives of the contraction curves obtained by the sensor. Norepinephrine (NE) and isoproterenol (ISO) increased the contractility in cultured myocytes in a dose-dependent fashion. In the preparation of rat ventricular papillary muscle, NE- and ISO-induced increase in the Vm in the radial direction significantly correlated with the increase in tension measured with a force-displacement transducer. These results indicate that the Fotonic Sensor is an appropriate instrument for evaluating the chronotropy and the contractility of cultured myocytes.

Animals↗
PubMed1993

[Successful surgery for pulmonary aspergillosis progressing to subacute process].

A 59-year-old woman with diabetes and rheumatoid arthritis was given prednisolone following the diagnosis of rheumatoid lung disease. She developed fever and bloody sputum, and chest X-ray showed a massive shadow in the right lower lung field. Chest CT revealed a giant massive shadow with unclear margin in the right posterior lower lobe. With enhancement, a round low density area appeared in the shadow. Aspergillus hyphae were detected from a bronchial brushing specimen. Pulmonary aspergillosis was diagnosed administration of anti-fungal agents was commenced but the improvement was not satisfactory. Surgical resection, which may be curative, was subsequently performed. The resected lung contained an aspergillus ball formation within an enlarged bronchus, that is, a bronchial aspergilloma, surrounded by widespread inflammatory cell infiltration. Most pulmonary aspergillomas are of the "colonization type", but in our case progression to subacute process occurred according to the extent of our patient's immunological reaction. For the treatment of localized pulmonary aspergillosis, our results suggest that surgery is recommended.

Arthritis, Rheumatoid↗
PubMed1993

[Effects of ethanol on Gi protein function in rat cerebral cortex of Wistar and Fischer 344 rats: evaluation by low pH treatment].

The present study was designed to provide further information regarding the effect of ethanol on the function of inhibitory GTP-binding (Gi) protein. To eliminate the Gs function in the regulation of adenylyl cyclase, cerebral cortex membranes from Wistar or Fischer 344 rats were pretreated at pH 4.5 ("low pH"), whereupon Gpp(NH)p-dependent inhibition of forskolin-stimulated adenylyl cyclase was examined. In the membranes from Wistar rats, ethanol (100 or 250 mM) resulted in left-shifted Gpp(NH)p inhibition curves and reduced IC50 values for Gpp(NH)p in an ethanol dose-dependent manner. In contrast, ethanol exhibited no effect on the Gpp(NH)p-dependent inhibition of the enzyme or on IC50 values for Gpp(NH)p in the membranes from Fischer 344 rats. These results are consistent with the idea that ethanol, in vitro, enhances the Gi function in the cerebral cortex of Wistar rats, and that ethanol's effect on Gi protein in the cerebral cortex is different in Wistar and Fischer 344 rats.

Animals↗
PubMed1992

Practical usage concentrations of monensin have non-specific actions other than as a sodium ionophore in rat parotid acinar cells.

Monensin is used as a sodium ionophore to examine the effect of Na+ on cellular function in a variety of cell types. In the present study, we investigated the effects of different concentrations of monensin on the signal transduction system in exocrine parotid acinar cells. Monensin increased cytosolic free Na+ concentration, measured by the Na+ indicator sodium-binding benzofuran isophthalate in a concentration-dependent manner (0.01 to 100 microM). Likewise, monensin concentration-dependently increased amylase release and intracellular Ca2+ concentration in the presence and the absence of extracellular Ca2+. Low concentrations (0.01 to 1 microM) of monensin did not release Ca2+ from non-mitochondrial intracellular pools in permeabilized cells with saponin but high concentrations (10 and 100 microM) of monensin which are of practical usage did. Monensin itself did not change the cyclic AMP accumulation, whereas high concentrations (10 and 100 microM) but not low concentrations (0.01 to 1 microM) of monensin inhibited cyclic AMP accumulation elevated by isoproterenol in the presence and absence of extracellular Na+. These results indicate that high concentrations of monensin, which are practically used, have nonspecific actions in rat parotid acinar cells, and lower concentrations of monensin are recommended for use as a sodium ionophore.

Adenosine Triphosphate↗
PubMed1991

The thapsigargin-sensitive intracellular Ca2+ pool is more important in plasma membrane Ca2+ entry than the IP3-sensitive intracellular Ca2+ pool in neuronal cell lines.

In NG108-15 cells, bradykinin (BK) and thapsigargin (TG) caused transient increases in a cytosolic free Ca2+ concentration ([Ca2+]i), after which [Ca2+]i elevated by TG only declined to a higher, sustained level than an unstimulated level. In PC12 cells, carbachol (CCh) evoked a transient increase in [Ca2+]i followed by a sustained rise of [Ca2+]i, whereas [Ca2+]i elevated by TG almost maintained its higher level. In the absence of extracellular Ca2+, the sustained elevation of [Ca2+]i induced by each drug we used was abolished. In addition, the rise in [Ca2+]i stimulated by TG was less affected after CCh or BK, whereas CCh or BK caused no increase in [Ca2+]i after TG. TG neither increased cellular inositol phosphates nor modified the inositol phosphates format on stimulated by CCh or BK. We conclude that TG may release Ca2+ from both IP3-sensitive and -insensitive intracellular pools and that some kinds of signalling to link the intracellular Ca2+ pools and Ca2+ entry seem to exist in neuronal cells.

Animals↗
PubMed1991

Interaction between PAF and drugs that stimulate formation of inositol phosphates.

1. We examined the effect of platelet-activating factor (PAF) on alpha 1-adrenergic and muscarinic cholinergic receptors in the membranes of rat parotid and the functional responses to norepinephrine (NE) and carbamylcholine (CCh) in exocrine secretion. 2. Pretreatment of parotid slices with 1 microM PAF caused a significant decrease the density of [3H]prazosin and [3H]quinuclidinyl benzilate binding sites without a change in the affinity. 3. In functional studies, pretreatment of parotid slices with 1 microM PAF markedly reduced the increase in intracellular 3H-labeling of inositol phosphates induced by NE and CCh. However, the EC50 values for NE and CCh stimulation of [3H]inositol phosphates in 1 microM PAF treated slices were significantly higher when compared to those of controls. 4. In addition, NE- and CCh-induced K+ release from parotid slices were also inhibited by PAF (1 microM) treatment. CV3988, a PAF antagonist, protected against these PAF-induced changes. 5. These results suggests that PAF-induced downregulation of alpha 1-adrenergic and muscarinic cholinergic receptors is mediated through specific PAF receptors in rat parotid glands, and that PAF could be a mediator which alters alpha 1-adrenergic and muscarinic cholinergic responses.

Animals↗
PubMed1991

[Mechanism of activation of receptor-operated calcium entry in non-excitable cells].

Inositol phosphates have an important role in Ca2+ mobilization and especially inositol 1, 4, 5-trisphosphate (IP3) is now believed to release Ca2+ from the endoplasmic reticulum (ER). On the other hand, the mechanism of activation of Ca2+ entry is unknown. Non-excitable cells have only receptor-operated Ca2+ channels, lacking voltage-operated Ca2+ channels, and are a useful system for studying signal transduction. In this review, some mechanisms for the regulation of Ca2+ entry in non-excitable cells are discussed and a new hypothesis originally proposed by Putney (1986), the capacitative Ca2+ entry model, is focussed. In this model, Ca2+ influx across the plasma membrane is increased when the IP3-sensitive Ca2+ pools is emptied. Capacitative Ca2+ entry is now confirmed in rat parotid acinar cells by studies on the refilling process for intracellular Ca2+ pools and by using the microsomal Ca(2+)-ATPase inhibitor thapsigargin, which does not increase cellular IP3. Finally, capacitative Ca2+ entry is expected to exist in a variety of cell types including excitable cells.

Animals↗
PubMed1991

Enhancement in beta-adrenergic responsiveness of adenylate cyclase in rat liver after galactosamine administration.

In rat liver at 48 hours after galactosamine (GalN) treatment, isoproterenol-induced accumulation of cyclic AMP and activation of adenylate cyclase (AC) were significantly enhanced. AC activity stimulated with GppNHp or NaF was also augmented in membranes from GalN-treated rats. However, the MnCl2-stimulated or forskolin-stimulated activity in GalN-treated rats did not differ from the control. These data suggest that the beta-adrenergic responsiveness of AC in rat liver is potentiated, possibly due to the enhanced function of the Gs protein, during the process of regeneration after GalN treatment.

Adenylyl Cyclases↗
PubMed1991

Stable inhibition of adenylate cyclase by muscarinic agonist in rat parotid gland: effects of neomycin and pertussis toxin.

Treatment of rat parotid slices with carbachol (CCh) resulted in the stable inhibition of isoproterenol-induced activation of adenylate cyclase (AC); the inhibition of the enzyme was persistently observed in washed membrane prepared from parotid slices pretreated with CCh. Methoxamine, but not clonidine, also caused stable inhibition. Activation of AC by 5'-guanylylimidodiphosphate (GppNHp) and by NaF was also attenuated by treatment with either CCh or methoxamine, indicating reduction of the Gs protein function. Pertussis toxin treatment prevented CCh-induced inhibition of the enzyme. However, MnCl2-stimulated and forskolin-stimulated activity, and the inhibition of forskolin-stimulated activity by GppNHp were not altered by CCh treatment. It appears, therefore, that the stable muscarinic inhibition of AC involves the Gi protein, but it does not result from the inhibitory regulation of AC activity by the interaction between the Gi protein and the catalytic unit of AC. Furthermore, the inhibition of GppNHp-stimulated AC activity by CCh was effectively reversed by the pretreatment of slices with neomycin. This suggests that the stimulation of phosphoinositide hydrolysis elicited by CCh possibly participates in stable muscarinic inhibition of AC presumably by reducing the function of the Gs protein. Thus, in the rat parotid gland, CCh appears to cause a stable inhibition of AC through two different mechanisms; one is associated with the Gi protein and the other is associated with the stimulation of phosphoinositide metabolism.

Adenylate Cyclase Toxin↗
PubMed1990

Residual secretion of amylase induced by isoproterenol from rat parotid gland slices.

1. During pretreatment with isoproterenol (ISP) for 2 min the accumulation of cyclic AMP increased in a dose-dependent manner but amylase release did not increase even in the highest dose of ISP used. 2. After a brief pretreatment with ISP, the following 10-min incubations with fresh medium without ISP caused increase in amylase secretion (residual secretion). However, cyclic AMP accumulation returned to the non-treated level during the residual secretion of amylase. 3. Both residual amylase release and cyclic AMP accumulation after pretreatment with ISP were enhanced in the presence of isobutyl-methylxanthine. Residual amylase release was not affected in the absence of extracellular calcium ion. 4. We suggest that there may be another pathway than cyclic AMP to cause residual amylase secretion induced by brief pretreatment with ISP in rat parotid acinar cells.

1-Methyl-3-isobutylxanthine↗