Masked excitatory action of noradrenaline on rat islet β-cells via activation of phospholipase C

The effect of noradrenaline (NE) on rat islet -cells was examined. NE reduced insulin secretion from rat islets exposed to extracellular solutions containing glucose at 5.5 or 16.6 mM. In islets treated with pertussis toxin (PTX), however, NE increased insulin secretion. The NE-induced augmentation of insulin secretion was inhibited by prazosin. In intact islets, NE increased phospholipase C (PLC) activity, an effect that was prevented by treatment of islets with U-73122. NE elevated intracellular [Ca²⁺] ([Ca²⁺]_i) in isolated -cells independently of PTX. Although this NE effect was inhibited by prazosin, phenylephrine did not mimic it. The [Ca²⁺]_i response to NE was also prevented by the treatment of cells with U-73122. NE produced depolarization of -cells followed by nifedipine-sensitive action potentials. NE reduced the whole-cell membrane currents through ATP-sensitive K⁺ channels (K_ATP), responsible for the depolarization. This NE effect was prevented by treatment of -cells with U-73122 or BAPTA/AM. Although at least some of our results imply the presence of ₁-adrenoceptors, -cells were not stained by a polyclonal IgG antibody recognizing all adrenergic ₁-receptor subtypes so far identified. These results suggest that an interaction of NE with an unknown type of receptor activates rat islet -cells via a PLC-dependent signal pathway. This effect is, however, masked by the inhibitory action via a PTX-sensitive pathway also activated by NE.     

Amino acid substitutions in NS5A region of GB virus C and response to interferon therapy

GB virus C (GBV-C) is related to hepatitis C virus (HCV) and has a similar genomic structure. Some predictors for the efficacy of interferon (IFN) therapy on HCV have been reported: genotype, viral load, IFN dose, and the amino acid substitutions in the NS5A region, designated as the interferon sensitivity determining region (ISDR). To evaluate the correlation between the amino acid substitutions in the GBV-C NS5A region and the response to IFN therapy, single-strand conformation polymorphism (SSCP) analysis was performed in the 12 concomitantly GBV-C-and HCV-infected patients who received IFN therapy at three time points: before, end-point, and after the IFN therapy. The region in the GBV-C NS5A studied includes the amino acids that exhibit some homology to the ISDR and the various substitutions. By SSCP analysis, amplicons were separated into 1-4 bands, which indicated the existence of heterogeneity in each host. However, the deduced amino acid sequences in these bands exhibited no characteristic differences among these strains irrespective of response to IFN therapy. Of the 32 strains separated by SSCP, 7 strains were responders, and 25 were nonresponders. The mean amino acid substitution, compared with the consensus sequence of nonresponders, was 1.00+/-0.93 among responders, and 1.40+/-0.85 among non-responders (P= NS). No correlation between the amino acid sequence in the GBV-C NS5A region and response to IFN therapy was found, indicating that the GBV-C NS5A region dose not act as the ISDR.     

A pore-forming toxin produced by Aeromonas sobria activates Ca2+ dependent Cl- secretion

Bacteria produce many types of hemolysin that induce diarrhea by mechanisms that are not completely understood. Aeromonas sobria hemolysin (ASH) is a major virulence factor produced by A. sobria, a human pathogen that causes diarrhea. Since epithelial cells in the intestine are the primary targets of hemolysin, we investigated the effects of ASH on ion transport in human colonic epithelial (Caco-2) cells. ASH increased short-circuit currents (Isc) in a dose-dependent manner, and it also activated a 125I efflux from Caco-2 cells. ASH-induced Isc increases and 125I efflux activations were both suppressed by low Ca2+ levels in the extracellular solution or by pretreatment with the Ca2+ chlelator BAPTA-AM. Intracellular Ca2+ levels were increased by ASH in a biphasic fashion characterized by a rapid sharp increase (peak 1) followed by a sustained low plateau (peak 2). ASH-induced peak 1 was inhibited by pretreatment with pertussis toxin, indicating that Ca2+ was mobilized from intracellular stores, and peak 2 was induced by an influx of extracellular Ca2+. Peak 2 but not peak 1 was related to Cl- secretion. These results indicate that ASH activates Ca2+-dependent Cl- secretion.     

Effect of murine recombinant interferon-gamma in the protection of mice against Salmonella

The ability of recombinant murine (rMu) interferon (IFN)-gamma to activate anti-Salmonella-activity in normal mice and beige mutant (bg/bg) mice with Chediak-Higashi syndrome (CHS) was examined. Previous intraperitoneal (i.p.) injection of rMuIFN-gamma (10(4) U per mouse) significantly hindered the bacterial growth in the peritoneal cavities, spleens and livers of the mice after the i.p. infection with Salmonella enteritidis No. 11 strain. It was also effective on the beige mice that have phagocytic cells with a genetically impaired bactericidal function, suggesting that IFN-gamma activates the pathway irrelevant to the beige mutation. The effect was the maximum, when IFN-gamma was given 6 h before the challenge. The effect seemed to be due to the augmentation of bactericidal capacity rather than the prevention of systemic spread of bacteria. Recombinant human IFN-alphaA/D (10(2)-10(6) U per mouse), which produced effects identical to those of murine IFN-beta, did not show such a bactericidal effect. Bactericidal activity enhancement was also seen in mice that had been injected with a small amount of rMuIFN-gamma (10(2) U) and bacterial lipopolysaccharide (LPS) (10 ng) together at 6 h before the challenge, although the IFN-gamma or LPS alone at these doses produced very little if any effect. Bactericidal effect enhancement was seen in mice that had been injected with IFN-gamma at 6 h and LPS at 3 h before the challenge, while it could be hardly seen in mice injected with them in a reversed order.(ABSTRACT TRUNCATED AT 250 WORDS)     

The inhibitory effect of oxatomide, an anti-allergic agent, on eosinophil-mediated and eosinophilic cell line-mediated natural cytotoxicity against bronchial epithelial cells

Recently, eosinophils have been implicated as inflammatory effector cells in allergic and inflammatory reactions such as bronchial asthma. In this study eosinophil-mediated and eosinophilic cell line-mediated natural cytotoxicity against bronchial epithelial cells and the effects of oxatomide, an anti-allergic agent, on their cytotoxicity were investigated. Treatment with oxatomide diminished both eosinophil-mediated and eosinophilic cell line-mediated natural cytotoxicity in vitro. We concluded from these results that oxatomide not only has anti-allergic activity but also anti-inflammatory properties for eosinophils. In addition this method for isolating eosinophils seems to well serve the purpose of evaluating eosinophil function as in this investigation, as we have reported previously.     

The significance of the determination of AFP-isoform in the early diagnosis of hepatocellular carcinoma]

To evaluate the significance of the determination of the AFP-isoform in the early diagnosis of hepatocellular carcinoma (HCC), the AFP-isoform was determined in 48 patients with HCC and in 53 patients with liver cirrhosis, using the lectin electrophoresis of AFP by antibody-affinity blotting technique. 1. The HCC-type AFP-isoform was detected in 44 of the 48 patients with HCC, 2. In about 30% of the patients with HCC, the HCC-type AFP-isoform appeared 3-10 months before the graphic diagnosis of HCC, 3. In about 60% of the patients with liver cirrhosis found to have the HCC-type AFP-isoform, HCC developed within one year. Thus, the serial determination of the AFP-isoform in patients with liver cirrhosis was considered very useful for the early diagnosis of HCC.     

Accelerated age-dependent decline in the T suppressor capacity of SJL mice

Tolerance induction with rabbit gamma-globulin was employed as a probe for age-dependent changes in suppressor capacity of SJL lymphoid cells. The tolerant state was assessed by loss of cooperative capacity and by infectious tolerance. The supply of precursor cells was assessed by thymectomy and by treatment with colchicine and cyclophosphamide, which have been reported to eliminate suppressor cells. Thymectomy, 16-18 days before tolerance induction, did not affect antibody response or tolerance inducibility; thymectomy, 33 days before tolerance induction, reduced both antibody response and tolerance inducibility. Colchicine, injected together with aggregate-freed rabbit gamma-globulin, inhibited tolerance induction partially in 35-day-old mice and completely in 106-day-old mice. Colchicine, given to younger mice, thymectomized 17 days before tolerance induction, prevented tolerance induction completely. A low dose of cyclophosphamide interfered with tolerance induction in older, but not in younger mice. A high dose of cyclophosphamide interfered with tolerance induction in thymus cells of younger and older mice. After thymectomy, there was a much more profound interference of a low dose of cyclophosphamide with tolerance induction. Results were discussed in terms of an age-dependent decline of thymus progenitors and of peripheral progenitors of suppressor cells.     

Improvement of action myoclonus by an administration of 5-hydroxytryptophan and carbidopa in a child with muscular subsarcolemmal hyperactivity

We report a 3-year-11-month-old boy who manifested action myoclonus only. Histochemical analysis of the quadriceps muscle revealed subsarcolemmal hyperactivity. The administration of 5-hydroxytryptophan and carbidopa dramatically improved the action myoclonus and reduced an amplitude of giant somatosensory evoked potentials. A nosological relation of this case with "essential myoclonus" and mitochondrial encephalomyopathy was discussed.     

Increase in choroidal blood flow in rabbits with endothelin-1 induced transient complete obstruction of retinal vessels

Background: In a previous paper, we reported that retinal blood flow (RBF) ceased immediately after injection of 1 nmol endothelin-1 (ET-1) and no recovery of RBF was detected for at least 50 min. In this study, we confirmed the same duration of RBF cessation and measured choroidal blood flow (CBF) for 180 min. Methods: We measured CBF in a rabbit model of transient complete obstruction of retinal vessels induced by intravitreal injection of a high dose of ET-1, using the hydrogen clearance method. We also investigated the effects of intravitreal injection of ET-1 on intraocular pressure (IOP), blood pressure, pulse rate and blood gases. Results: CBF was significantly greater in the ET-1-injected eyes than in the control eyes 40–130 min after injection of ET-1 (P < 0.05). The maximal CBF ratio in the ET-1-injected eyes was 128 ± 7.4% at 40 min. CBF decreased to the pre-injection level at 140 min after the injection of ET-1. There was no significant change in blood pressure, pulse rate and blood gases throughout this experiment, and there was no significant difference in IOP between ET-1-injected eyes and control eyes. Conclusion: It seems likely that the increase in CBF resulted from some local mechanisms of control that compensated for the decrease in RBF induced by intravitreal injection of ET-1. This model may be useful for investigation of the regulatory system of intraocular circulation, including endothelin receptors.     

Intra-arterial chemotherapy via reservoir system for advanced bladder cancer and prostate cancer

A clinical study was performed on the efficacy of intra-arterial chemotherapy using a reservoir system for advanced urological malignancies. The reservoir system was indwelted in the femoral subcutaneous layer by Seldinger's method. Fifteen cases of inoperable complicated advanced bladder cancer and 10 cases of postoperative local recurrent bladder cancer were administered intra-arterial chemotherapy using a reservoir system. Then, 23 cases of local relapsed prostate cancer and two cases of endpocrine-resistant prostate cancer were administered the chemotherapy. The administered anti-cancerous agents were methotraxate, cis-platinum and adriamycin, then 5-FU or carboplatin was administered as maintenance therapy. The mean number of courses of chemotherapy was six for bladder cancer and four for prostate cancer. During stabilization of the local lesion, no distant deterioration was recognized. The overall clinical efficacy was a positive response (PR) and no change (NC): for 18 and 7 cases of bladder cancer, and 11 and 14 cases of prostate cancer, respectively. The median duration of stabilization was 23 months for bladder cancer and 12 months for prostate cancer. The adverse effects were fever than those with systemic chemotherapy.