A ribonucleotide reductase gene involved in a p53-dependent cell-cycle checkpoint for DNA damage

The p53 gene is frequently inactivated in human cancers. Here we have isolated a p53-inducible gene, p53R2, by using differential display to examine messenger RNAs in a cancer-derived human cell line carrying a highly regulated wild-type p53 expression system. p53R2 contains a p53-binding sequence in intron 1 and encodes a 351-amino-acid peptide with striking similarity to the ribonucleotide reductase small subunit (R2), which is important in DNA synthesis during cell division. Expression of p53R2, but not R2, was induced by ultraviolet and gamma-irradiation and adriamycin treatment in a wild-type p53-dependent manner. Induction of p53R2 in p53-deficient cells caused G2/M arrest and prevented cells from death in response to adriamycin. Inhibition of endogenous p53R2 expression in cells that have an intact p53-dependent DNA damage checkpoint reduced ribonucleotide reductase activity, DNA repair and cell survival after exposure to various genotoxins. Our results indicate that p53R2 encodes a ribonucleotide reductase that is directly involved in the p53 checkpoint for repair of damaged DNA. The discovery of p53R2 clarifies a relationship between a ribonucleotide reductase activity involved in repair of damaged DNA and tumour suppression by p53.

Role of Kupffer cells and gut-derived endotoxins in alcoholic liver injury

The hepatotoxic effects of alcohol have been described in detail, but factors responsible for its hepatotoxicity have only partially been characterized. For example, it is known that chronic ethanol ingestion increases hepatotoxicity and produces fatty liver, hepatitis and cirrhosis. However, acute ethanol consumption reduces endotoxin hepatotoxicity. It now appears that Kupffer cells participate in several aspects of these phenomena. Previously, most studies on the effects of alcohol on liver function have focused chiefly on the hepatocyte. Recently, attention has been directed towards the effect of ethanol ingestion on Kupffer cell function, which is stimulated by gut-derived endotoxins (lipopolysaccharides) via mechanisms dependent on increased gut permeability and the possible relationship between Kupffer cells and alcohol-induced liver injury. Here we will review new evidence for the proposal that Kupffer cells and endotoxins play a pivotal role in hepatotoxicity following alcohol exposure, based on studies using the continuous intragastric enteral feeding model developed by Tsukamoto and French and an acute model developed by us.

Cure of Helicobacter pylori infection does not improve symptoms in non-ulcer dyspepsia patients-a double-blind placebo-controlled study

BACKGROUND

It remains controversial whether the cure of H. pylori infection improves NUD symptoms.

AIM

To conduct a double-blind placebo-controlled single centre study with concealed allocation to investigate this question.

PATIENTS AND METHODS

Ninety NUD patients with H. pylori infection were randomly assigned to either the treatment group (50 patients) or placebo group (40 patients). The treatment group received omeprazole, amoxycillin, clarithromycin and the placebo group received omeprazole and placebos for 7 days. Symptoms were assessed every week for up to 12 weeks after completion of medication by a symptom questionnaire. Alteration of histological parameters for gastritis was also evaluated.

RESULTS

The infection was cured in 41 out of 48 patients in the treatment group and none in the placebo group. There was no significant difference in the mean symptom scores at any assessment point up to 12 weeks between the treatment and placebo groups. Regarding histological parameters, activity and inflammation, not atrophy or intestinal metaplasia, were significantly improved in the treatment group.

CONCLUSION

Although histological parameters were significantly improved in the treatment group, there was no significant improvement in symptoms of NUD in the treatment group compared to placebo.

Characterization of dihydropyrimidine dehydrogenase on immunohistochemistry in colon carcinoma, and correlation between immunohistochemical score and protein level or messenger RNA expression

BACKGROUND

Dihydropyrimidine dehydrogenase (DPD) is the first enzyme that metabolizes 5-fluorouracil (5-FU). Until now, enzymatic activity or mRNA expression of DPD has been investigated. However, there are no papers on immunohistochemical evaluation of DPD. We investigated DPD staining on immunohistochemistry, and examined the relationship among immunohistochemical score, protein level and mRNA expression of DPD.

MATERIALS AND METHODS

Forty-seven resected colon cancer specimens, four colon cancer cell lines, two xenografts by colon cancer cell lines, and human mononuclear cells were used. Immunohistochemistry was performed using DPD monoclonal antibody. Protein levels were determined by Western blot analysis. And mRNA levels were calculated by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

DPD was strongly expressed in the cytoplasm of cancer cells, and in the cytoplasm of macrophage and plasma cells. The immunohistochemical score was more correlated with protein levels (P = 0.0054) than mRNA expression (P = 0.9028).

CONCLUSIONS

We investigated the characterization of DPD immunohistochemically, and showed that immunohistochemical expression of DPD can be used to predict the sensitivity of colorectal carcinomas to 5-FU.

Identification of seven genes regulated by wild-type p53 in a colon cancer cell line carrying a well-controlled wild-type p53 expression system

We applied a differential display method to screen mRNAs isolated from a newly established cell line that carried a wild-type p53 transgene under control of the lactose operon. To investigate the p53 signaling pathway, we looked for genes whose expression was significantly induced or suppressed by induction of wild-type p53 protein, and identified seven. DNA sequence analyses revealed that the two genes that were upregulated encoded isozyme 6 of aldehyde dehydrogenase (ALDH6) and subunit I of cytochrome c oxidase (COI). The five genes that were downregulated encoded protein-tyrosine kinase (Syk), high mobility group chromosomal protein 17 (HMG-17), transferrin receptor, human alpha-tubulin, and sds22-like protein. The results indicated that genes related to cell cycle regulation, cell respiration, and cytoskeletal structure are involved in the process of growth arrest induced by wild-type p53.

[A case of polymyositis presenting pregnancy with acute respiratory failure]

A 33-year-old pregnant woman developed respiratory difficulty with bilateral pleural effusion 31 weeks into gestation. On admission she had an elevated serum level of creatine kinase, but muscle weakness in the extremities was mild. After an immediate and successful Cesarean section, she developed respiratory failure and mechanical ventilation was required. The patient was diagnosed as having polymyositis from the limb muscle biopsy. She was treated with dexamethasone at a dose of 8 mg, methylprednisolone++, 1 g daily for three days, and then prednisolone 60 mg daily. One week later the serum level of creatine kinase was normalized and the patient was weaned from ventilator support. The dose of prednisolone was tapered 10 mg every week and she was discharged two months after delivery without prednisolone. A chest CT scan revealed no interstitial pneumonitis or aspiration pneumonia, so her respiratory failure seemed to be ascribable to polymyositis-related respiratory muscle weakness and pleural effusion. However, severe involvement of respiratory muscles without generalized marked muscle weakness is extremely rare, and pleural complications have usually been described in association with pulmonary parenchymal diseases. During the following two years polymyositis has not recurred in this patient and there have been no data indicative of other overlapping collagen diseases. Reports of polymyositis which occurred during pregnancy are rare, and the pathogenesis and clinical outcome of these patients need to be carefully investigated.

Taurine preserves gap junctional intercellular communication in rat hepatocytes under oxidative stress

Gap junctional intercellular communication (GJIC) between hepatocytes is important for the maintenance of differentiated liver functions. Taurine is known to be cytoprotective, and is used clinically to improve liver functions. We evaluated the effect of taurine on GJIC in hepatocyte doublets under oxidative stress. Hepatocyte doublets were isolated from female Wistar rats, using a collagenase perfusion technique, and cultured in Leibovitz-15 medium containing fetal bovine serum (10%). H2O2 (2 mM) and/or taurine (0.1-1 mM) were added 2 h after inoculation, and the culture was incubated for 3 h. Fluorescent dye (Lucifer Yellow CH) coupling between adjacent cells was evaluated by microinjection. The distribution and quantity of connexin 32 (Cx32) in hepatocytes were detected using indirect immunofluorescence analysis and Western blotting. Steady state mRNA levels of Cx32 were detected by Northern blotting. The percentage of dye coupling 5 h after inoculation was 88 +/- 6.3% in the control. however, this was decreased to almost half the control value by H2O2. Taurine prevented the decrease caused by H2O2 in a dose-dependent manner. Immunofluorescence analysis for Cx32 demonstrated numerous punctate fluorescent spots along the intercellular plasma membrane in controls, which were significantly decreased by H2O2. Taurine prevented the decrease of Cx32. Western blot analysis also showed the decrease of Cx32 protein levels by H2O2 treatment, which decrease was prevented by taurine. Interestingly, H2O2 and/or taurine treatments did not affect Cx32 mRNA levels. Our findings indicated that H2O2 treatment decreased GJIC between hepatocytes, most likely due to augmenting the degradation of Cx32 proteins, whereas taurine prevented this process. This effect of taurine is beneficial for the preservation of differentiated functions in the liver under oxidative stress.

Viability of Q-wave infarcted myocardium with restored positive and persistent negative T waves after optimal revascularization compared with dobutamine stress echocardiography

To clarify the clinical difference in viability of myocardium with negative and positive T waves in Q-wave anterior or anteroseptal myocardial infarction, we performed low-dose dobutamine stress echocardiography in 17 patients with negative T waves and in 13 patients with positive T waves with optimal revascularization of infarct-related arteries in the chronic phase of infarction. At baseline the wall motion score (WMS) of the negative and positive T groups was 25.8 +/- 3.0 and 22.3 +/- 2.2 points (p <0.05), respectively. At peak stress WMS in each group was 27.2 +/- 4.2 and 19.8 +/- 2.4 points (p <0.0001), respectively. With dobutamine stress WMS in the positive T group was more decreased than that of the negative T group (p <0.0001). We conclude that the restored positive T waves in Q-wave myocardial infarction indicate a significantly greater amount of viable myocardium than the negative T waves, showing better regional wall motion improvement with low-dose dobutamine stress.

Efficacy of reduced dosage of rabeprazole in PPI/AC therapy for Helicobacter pylori infection: comparison of 20 and 40 mg rabeprazole with 60 mg lansoprazole

Proton pump inhibitor (PPI)- based triple therapy has been a recent trend for treatment of Helicobacter pylori infection, with the PPI-amoxicillin-clarithromycin (PPI/AC) regimen being one of the most popular. We have reported the effectiveness of PPI/AC regimens in the Japanese population and have demonstrated that the effectiveness of 40 mg rabeprazole, a recently developed PPI, is similar to that of 40 mg of omeprazole and 60 mg of lansoprazole when used in combination with amoxicillin and clarithromycin. In this study, we focused on whether 20 mg of rabeprazole is effective in our patient population by comparing that dosage with 40 mg of rabeprazole and 60 mg of lansoprazole. In all, 308 H. pylori-infected patients [236 men and 72 women; age (mean +/- SEM) 49.3+/-0.6 years] with peptic ulcer disease (N = 270) or nonulcer dyspepsia (N = 38) were randomly assigned to one of three different PPI/AC regimens for seven days: LAC (N = 104), consisting of lansoprazole 30 mg twice a day, amoxicillin 500 mg three times a day, and clarithromycin 200 mg twice a day; RAC (N = 104), consisting of rabeprazole 20 mg twice a day, amoxicillin 500 mg three times a day, and clarithromycin 200 mg twice a day; and the R1/2AC regimen (N = 100), which included rabeprazole 10 mg twice a day, amoxicillin 500 mg three times a day, and clarithromycin 200 mg twice a day. Cure of the infection was determined by the [13C]urea breath test one month after completion of the treatment. Intention-to-treat based and per-protocol based cure rates for the LAC, RAC, and R1/2AC regimens were 82.7 (95% CI, 74-89) and 88.7% (81-94), 85.6 (77-92) and 89.8% (82-95), and 87.0 (79-93) and 89.7% (82-95), respectively. Although adverse effects were reported by 20.3% of the patients, these affected compliance in only five patients in the RAC and LAC regimens and none in the R1/2AC group. Overall complete compliance was achieved in 94.7% of interviewed patients. In conclusion, the effectiveness of the PPI/AC regimen with 20 mg of rabeprazole is comparable with and even safer than that of 40 mg of rabeprazole and 60 mg of lansoprazole in our patient population.

Isolation and characterization of a novel TP53-inducible gene, TP53TG3

We applied the differential mRNA display method to isolate genes regulated by wild-type TP53 in cells of a colon-cancer line (SW480) in which we had established an inducible TP53 expression system under the control of the lactose operon. Here we report isolation and characterization of a novel TP53-inducible gene, termed TP53TG3 (TP53 target gene 3). Its DNA sequence was identical to sequences present in two BAC clones that had been mapped to chromosome band 16p13. The gene expressed several transcripts by alternative splicing; the two major transcripts, TP53TG3a and TP53TG3b, encoded 124- and 132-amino-acid peptides that were expressed predominantly in testis. Immunohistochemical analysis using cancer cells (HeLa or H1299) that had been transfected with plasmid DNA designed to express the MYC-fused TP53TG3 proteins indicated that these products were present mainly in the cytoplasm 20 hr after transfection. However, 40 hr after transfection, the recombinant proteins had accumulated in the nuclei of some cells. Because no known nuclear localization domain was present in the amino acid sequence, we suspect that this protein plays an important role in the TP53-mediated signaling pathway, when it forms complexes with other protein(s) and is transferred by them into the nucleus. Genes Chromosomes Cancer 26:329-335, 1999.

How useful is the detection kit for antibody to Helicobacter pylori in urine (URINELISA) in clinical practice?

OBJECTIVE

Increased knowledge of the significance of Helicobacter pylori (H. pylori) infection in gastric disorders has accelerated the trend of screening patients with dyspepsia for its infection. Serological examination of antibody for H. pylori has been widely performed. Recently, a urine-based enzyme-linked immunosorbent assay (URINELISA) kit for detection of antibody for H. pylori has been developed. Accordingly, we evaluated its diagnostic accuracy in clinical practice.

METHODS

Subjects of this study were 132 patients who presented at our university hospital because of dyspeptic symptoms (81 men, 51 women; age, 41.5+/-1.4 yr). 13C urea breath test, blood drawing for serological antibody for H. pylori infection by four different kits, and urine collection for the URINELISA test for detection of the antibody were performed. Diagnostic accuracy of the commercially available antibodies in serum and in urine were investigated using the results of the 13C urea breath test as the gold standard.

RESULTS

Sensitivity, specificity, and accuracy of URINELISA were 86.3% (95% confidence intervals [CI], 76-93%), 91.5% (95% CI, 81-97%), and 88.6% (95% CI, 82-93%), respectively, which were comparable to those of imported serological kits.

CONCLUSIONS

The URINELISA kit for detecting anti-H. pylori antibody in urine provides diagnostic accuracy comparable to that of imported kits for detecting antibodies in serum and is considered to be clinically useful for the diagnosis of H. pylori infection.

Partial-liver transplantation to treat familial amyloid polyneuropathy: follow-up of 11 patients

BACKGROUND

Recently, liver transplantation has been used to treat patients with familial amyloid polyneuropathy (FAP).

OBJECTIVE

To describe the clinical course of patients with FAP who received partial-liver transplantation from living donors.

DESIGN

Case series.

SETTING

University hospital in Matsumoto, Japan.

PATIENTS

11 patients with FAP who underwent partial-liver transplantation. The transthyretin gene abnormality in all 11 patients was the substitution of methionine for valine at position 30.

INTERVENTION

Partial liver transplantation from living donors.

MEASUREMENTS

Preoperative and follow-up (3 to 64 months) clinical data, including routine laboratory data, nerve conduction velocity tests, and sural nerve histology.

RESULTS

All 7 patients who had severe gastrointestinal autonomic disorders or polyneuropathy localized to the lower limbs for less than 4 years showed improvement. Three of 4 patients with polyneuropathy involving both the upper and lower limbs had adverse outcomes, including two deaths. The preoperative duration of their illness was more than 6 years. These 3 patients also had marked decreases in creatinine clearance and nerve conduction velocities and severe loss of myelinated fibers in sural nerves.

CONCLUSION

Preoperative clinical severity and duration of illness are associated with outcomes after liver transplantation for FAP.

[A case of relapsing polychondritis with oculobulbar symptoms and successful treatment of respiratory failure with BiPAP]

A 66-year-old man developed diplopia, ptosis, dysphagia, and acute respiratory failure. The initial diagnosis was myasthenia gravis and prednisolone had been administrated for three years. Because of recurrent upper respiratory infections, prednisolone was tapered off. Two months later, auricular chondritis, arthritis, and conjunctivitis appeared. He was diagnosed as having relapsing polychondritis on the basis of histological findings of the ear lobe biopsy. Reinstituted prednisolone had the effect on the auricular chondritis, arthritis, and conjunctivitis, but no effect on dysphagia, hoarseness, and respiratory failure caused by the deformity of the pharynx and airway. Tracheal collapse usually causes rapid death, so early tracheostomy and the use of endotracheal prostheses have been recommended in patients with airway obstruction from relapsing polychondritis, but such surgical management can only partially open up the large airways and has no effect on smaller airways. In this case tracheostomy and endoluminal stent placement have helped improve the patient's respiratory failure, but have had little effect on its aggravation at night in the supine position. The use of BiPAP after surgical management can be an effective treatment for airway involvement in relapsing polychondritis probably because it keeps the narrowed airways from collapsing, especially at night.

Renin-angiotensin system in elasmobranch fish: A review

The renin-angiotensin system (RAS) has been identified recently in elasmobranch fish, and the structure of angiotensin II (ANG II) is unusual ([Asp(1),Pro(3),Ile(5)]-ANG II) compared to other vertebrates. Receptors for ANG II have been identified in blood vessels and in a variety of osmoregulatory tissues including the gill, kidney and rectal gland. In addition, there is considerable binding to the interrenal gland and the stimulation of 1alpha-hydroxycorticosterone production in vitro suggests a physiological role in corticosteroidogenesis. ANG II is a potent vasoconstrictor and this effect does not appear to be mediated by sympathetic activation or catecholamine release. Although the RAS may not be involved in maintaining basal blood pressure, it may be important in situations in which blood pressure is reduced. Understanding of the role of ANG II as an osmoregulatory hormone is only just emerging with putative roles in the control of gill, rectal gland and perhaps, drinking. In addition, the stimulation of corticosteroid secretion may provide another means of controlling osmoregulation. J. Exp. Zool. 284:526-534, 1999.

Structural and functional evolution of the natriuretic peptide system in vertebrates

The natriuretic peptide (NP) system consists of three types of hormones [atrial NP (ANP), brain or B-type NP (BNP), and C-type NP (CNP)] and three types of receptors [NP receptor (R)-A, NPR-B, and NPR-C]. ANP and BNP are circulating hormones secreted from the heart, whereas CNP is basically a neuropeptide. NPR-A and NPR-B are membrane-bound guanylyl cyclases, whereas NPR-C is assumed to function as a clearance-type receptor. ANP, BNP, and CNP occur commonly in all tetrapods, but ventricular NP replaces BNP in teleost fish. In elasmobranchs, only CNP is found, even in the heart, suggesting that CNP is an ancestral form. A new guanylyl cyclase-uncoupled receptor named NPR-D has been identified in the eel in addition to NPR-A, -B, and -C. The NP system plays pivotal roles in cardiovascular and body fluid homeostasis. ANP is secreted in response to an increase in blood volume and acts on various organs to decrease both water and Na+, resulting in restoration of blood volume. In the eel, however, ANP is secreted in response to an increase in plasma osmolality and decreases Na+ specifically, thereby promoting seawater adaptation. Therefore, it seems that the family of NPs were originally Na(+)-extruding hormones in fishes; however, they evolved to be volume-depleting hormones promoting the excretion of both Na+ and water in tetrapods in which both are always regulated in the same direction. Vertebrates expanded their habitats from fresh water to the sea or to land during evolution. The structure and function of osmoregulatory hormones have also undergone evolution during this ecological evolution. Thus, a comparative approach to the study of the NP family affords new insights into the essential function of this osmoregulatory hormone.

Cardiovascular control via angiotensin II and circulating catecholamines in the spiny dogfish, Squalus acanthias

The contributions of circulating angiotensin II (Ang II) and catecholamines to cardiovascular control in the spiny dogfish were investigated by monitoring the effects of exogenous and endogenous dogfish [Asn1, Pro3, Ile5]-Ang II (dfAng II) on plasma catecholamine levels and blood pressure regulation. Bolus intravenous injections of dfAng II (30-1200 pmol kg-1) elicited dose-dependent increases in plasma adrenaline and noradrenaline concentrations, caudal artery pressure (PCA), and systemic vascular resistance (RS), and a decrease in cardiac output (Q). Similar injections of Ang II in dogfish pre-treated with the alpha-adrenoceptor antagonist yohimbine (4 mg kg-1) also elicited dose-dependent increases in plasma catecholamine levels yet the cardiovascular effects were abolished. Dogfish treated with yohimbine were hypotensive and had elevated levels of plasma Ang II and catecholamines. Intravenous injection of the smooth muscle relaxant papaverine (10 mg kg-1) elicited a transient decrease in PCA and RS, and increases in plasma Ang II and catecholamine levels. In dogfish first treated with lisinopril (10(-4) mol kg-1), an angiotensin converting enzyme inhibitor, papaverine treatment caused a more prolonged and greater decrease in PCA and RS, an attenuated increase in plasma catecholamines, and no change in plasma Ang II. By itself, lisinopril treatment had little effect on PCA, and no effect on RS, plasma Ang II or catecholamines. In yohimbine-treated dogfish, papaverine treatment elicited marked decreases in PCA, RS, and Q, and increases in plasma Ang II and catecholamines. Among the three papaverine treatments, there was a positive linear relationship between plasma Ang II and catecholamine concentrations, and the cardiovascular and hormonal changes were most pronounced in the yohimbine + papaverine treatment. Therefore, under resting normotensive conditions, while Ang II does not appear to be involved in cardiovascular control, catecholamines play an important role. However, during a hypotensive stress elicited by vascular smooth muscle relaxation. Ang II indirectly contributes to cardiovascular control by dose-dependently stimulating catecholamine release.

Comb-type copolymers for controlled DNA delivery

Various comb-type copolymer containing a polycation as a main chain was design to construct delivery systems of DNAs. The comb-type copolymers having cell-specific polysaccharides were proved to be useful to deliver DNA to the target cells in vivo. Of interest, the copolymers with abundant side chains of hydrophilic polymers are capable of stabilizing DNA triplex. Further, injectable nanoparticles for controlled releases of DNAs were fabricated from the copolymer and a biodegradable polymer.

Effects of nitric oxide synthase inhibition on the cerebral circulation and brain damage during kainic acid-induced seizures in newborn rabbits

The nitric oxide (NO) synthase inhibitor, N-omega-nitro-L-arginine methyl ester (L-NAME), was used to investigate the effect of endogenous NO on the cerebral circulation and brain damage during kainic acid (KA)-induced seizures in newborn rabbits. The cerebral blood flow (CBF), by laser doppler flowmetry, cerebral oxygenation (concentrations of oxy-(HbO2), deoxy-(HbR) and total hemoglobin (tHb) in brain tissue), by near-infrared spectroscopy (NIRS), mean arterial blood pressure (MABP), electroencephalography (EEG), and hippocampal neuronal damage were evaluated. Pretreatment with L-NAME caused significant decreases in CBF, HbO2, and tHb, and a significant increase in HbR during KA-induced seizures, compared with pretreatment with saline (P < 0.05), without a significant difference in MABP. Our study also demonstrated that pretreatment with L-NAME reduced the seizure activity and neuronal cell death in the hippocampus elicited by the systemic administration of KA in the neonatal brain. These results suggest that NO is of major importance in the neurodestructive process in spite of its roles in maintaining both the CBF and cerebral oxygenation during KA-induced seizures in the neonatal brain.

Impairment of inhibitory synaptic transmission in mice lacking synapsin I

Deletion of the synapsin I genes, encoding one of the major groups of proteins on synaptic vesicles, in mice causes late onset epileptic seizures and enhanced experimental temporal lobe epilepsy. However, mice lacking synapsin I maintain normal excitatory synaptic transmission and modulation but for an enhancement of paired-pulse facilitation. To elucidate the cellular basis for epilepsy in mutants, we examined whether the inhibitory synapses in the hippocampus from mutant mice are intact by electrophysiological and morphological means. In the cultured hippocampal synapses from mutant mice, repeated application of a hypertonic solution significantly suppressed the subsequent transmitter release, associated with an accelerated vesicle replenishing time at the inhibitory synapses, compared with the excitatory synapses. In the mutants, morphologically identifiable synaptic vesicles failed to accumulate after application of a hypertonic solution at the inhibitory preterminals but not at the excitatory preterminals. In the CA3 pyramidal cells in hippocampal slices from mutant mice, inhibitory postsynaptic currents evoked by direct electrical stimulation of the interneuron in the striatum oriens were characterized by reduced quantal content compared with those in wild type. We conclude that synapsin I contributes to the anchoring of synaptic vesicles, thereby minimizing transmitter depletion at the inhibitory synapses. This may explain, at least in part, the epileptic seizures occurring in the synapsin I mutant mice.

Teleost-type angiotensin is present in Australian lungfish, Neoceratodus forsteri

Angiotensin I (ANG I) was produced from the incubation of lungfish plasma with homologous kidney extracts. The purified peptide was found to have the sequence of H-Asn-Arg-Val-Tyr-Val-His-Pro-Phe-Thr-Leu-OH, which is homologous for the first eight residues with all teleost angiotensins so far sequenced, although lungfish generally possess tetrapod-type hormones. The lungfish decapeptide (ANG I) induced dose-dependent increases in arterial pressure in the rat. The lungfish octapeptide (ANG II) released aldosterone from kidney-adrenal tissue in vitro in a dose-dependent manner and induced dose-dependent increases in arterial pressure of the lungfish. Substitution of asparagine with aspartic acid in the first position (tetrapod-type ANG II) did not alter the blood pressure response significantly, but a second substitution of the valine in the (5)-position with isoleucine (ANG II form found in human and rat) abolished the rise in arterial pressure in lungfish over the same dose range.

[Ethanol-induced hepatic microcirculatory disturbance]

Alcoholic liver injury predominates in the pericentral region, in which oxygen tension is physiologically lowest. The enhanced injurious effect of ethanol at this site is postulated to be due to hypoxia, resulting from an enhanced oxygen demand of hepatocytes for the oxidative metabolism of ethanol. Moreover, we found that ethanol at higher concentrations induces hypoxia in the liver by causing microcirculatory disturbance. Upon initiation of ethanol infusion into the portal vein of isolated perfused rat liver at concentrations ranging from 25 to 100 mM, portal pressure began to increase in a concentration-dependent manner and reached maximal levels in 2-5 min (initial phase), followed by a gradual decrease over the period of ethanol infusion (escape phase). Sodium nitroprusside, a known vasodilator, diminished the ethanol-induced increase in portal pressure, increased oxygen consumption leading to inhibition of the reduction of the respiratory cytochromes of the liver, and diminished liver injury. The data indicate that the ethanol-induced hepatic vasoconstriction disturbs hepatic microcirculation, leading to hepatic hypoxia and hepatocellular injury. Endothelin-1 antiserum inhibited significantly hepatic vasoconstriction induced by ethanol. Cessation of infusion of endothelin-1 antiserum was followed by a subsequent increase in portal pressure. On the other hand, when a nitric oxide synthesis inhibitor, NG-monomethyl-L-arginine (L-NMMA), was infused into the portal vein simultaneously with ethanol, the initial phase of the response of portal pressure to ethanol was not altered and the peak values of portal pressure remained unchanged. However, following the peak increase in portal pressure, the rate of decrease was less than in the absence of L-NMMA. Thus, L-NMMA diminished the escape phase the sustained the vasoconstriction. Based on the current results, we propose that the sinusoidal tone in the presence of ethanol is regulated predominantly by the actions of the two endothelium-derived vasoactive factors, endothelin-1 and nitric oxide.