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Biomedical subjects

S Shiono

Publications and source records attributed to S Shiono.

At least 37 records · Page 2Linked to original sources
PubMed1995

Long-term hypothermic preservation of cardiac myocytes isolated from the neonatal rat ventricle: a comparison of various crystalloid solutions.

In this study, the functional and biochemical effects of crystalloid solutions on immature cardiac myocytes incubated under hypothermic conditions were evaluated. Cardiac myocytes were isolated from neonatal rat ventricles and cultured for 4 days, following which 12.5 x 10(5) myocytes per flask were incubated at 4 degrees C for 3, 6, 12, and 18 h in five types of crystalloid solutions: lactated Ringer's (LR), St. Thomas' Hospital (ST), University of Wisconsin (UW), 5% glucose-based potassium (GK), and normal saline (NS). The levels of creatine phosphokinase (CPK) and lactate dehydrogenase (LDH) in the solutions were measured after each hypothermic incubation, following which the myocytes were cultured for an additional 24 h at 37 degrees C to evaluate the recovery of the myocyte beating rate. In the LR, UW, and NS groups, the recovery ratios of the myocyte beating rate were over 95% of the control (the beating rate prior to hypothermic incubation) at 3 h, but decreased to 20.3, 15.1, and 0%, respectively, at 18 h. The ST and GK groups had significantly lower recovery ratios than the other three groups (72.9% and 63.4%, respectively) at 3 h. The release of CPK and LDH in the LR, UW, and NS groups was significantly suppressed compared to the ST and GK groups, with the greatest suppression observed in the LR group. Moreover, the ST and GK groups had the highest CPK and LDH levels, respectively. Thus, LR solution had the least cytotoxic effects, indicating that it could be the most suitable basic solution of the various cardioplegic or preservation solutions during the neonatal period.

Adenosine↗
PubMed1995

Hypoxic injury of immature cardiac myocytes under various hypothermic conditions using an in vitro cell-culture model.

The purpose of this study was to evaluate the functional and biochemical effects in immature cardiac myocytes under hypoxic and hypothermic conditions. Cardiac myocytes were isolated from neonatal rat ventricles and cultured for 4 days, after which 12.5 x 10(5) myocytes/flask were incubated under 3% hypoxic conditions at 4 degrees C, 10 degrees C, 15 degrees C, 20 degrees C, 25 degrees C, and 37 degrees C for 6, 12, and 24 h. After each hypoxic incubation, creatine kinase (CK) and lactate dehydrogenase (LDH) were measured in the incubation medium. The myocytes were then cultured for an additional 24 h at 37 degrees C to evaluate the recovery of the myocyte beating rate. In the 4 degrees C and 37 degrees C groups, the myocyte beating rate recovery markedly decreased with increasing incubation times from 78.1% and 97.2% at 6 h to 0.0% and 38.4% of the control, which was the beating rate prior to hypoxic incubation, at 24 h, respectively. However, in the 10 degrees C, 15 degrees C, and 25 degrees C groups, this value decreased significantly only at 24 h. In the 20 degrees C group, beating rate completely recovered in 24 h. A marked increase was found in the release of CK and LDH in the 4 degrees C group from 28.5 mIU/flask and 232.9 mIU/flask at 6 h to 83.7 mIU/flask and 640.7 mIU/flask at 24 h, respectively. However, in the 25 degrees C and 37 degrees C groups, this release was significantly increased only at 24 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

[A case of pulmonary arteriovenous fistula failed in transcatheter embolization and followed by emergency operation].

We reported a 55-year-old male case with pulmonary arteriovenous fistula. The lesion existed in right S9b and was about 6 cm in diameter. The afferent artery and the efferent vein, both were more than 10 mm in diameter, were shown on the chest CT and DSA film. At first transcatheter embolization with steel coils and Histoacryl was tried. Though we succeeded in embolization of the afferent artery, embolization of the fistula was failed because of reflux from the drainage vein. And a coil, a fragment of Histoacryl dropped and floated in the fistula. With concerning about the risk of embolization of the other organ with these materials, we performed the enucleation of the fistula at the next day. Although transcatheter embolization is useful in treating pulmonary arteriovenous fistula, in the case of wide communication with large drainage vein such as our case, it seems to be risky.

Arteriovenous Fistula↗
PubMed1995

The protective effect of probucol on adriamycin nephrosis in the rat.

Recent research has indicated the role of reactive oxygen species (ROS) in experimental nephritis. We examined the role of ROS and the effect of probucol, an anti-hyperlipidemic drug with antioxidant activity, on adriamycin (ADR)-induced nephrosis in the rat. Fourteen days after single intravenous injection of ADR (7.5 mg/kg b.w.), a nephrotic state was observed. Compared with the normal control values, the total kidney glutathione content was lower on day 5, but significantly higher on day 14 in the ADR-injected rats. Feeding ADR-injected rats with food containing 1% probucol was effective in reducing urinary protein excretion. Serum lipid peroxide level and kidney total glutathione content, both of which increased on day 14 in the ADR-injected rats, were also decreased significantly by concomitant probucol treatment. During long-term observation period of 18 weeks, probucol treatment relieved both urinary protein excretion and the progression of renal impairment. These protective effects of probucol suggest a role of ROS in the induction and progression of ADR nephrosis.

Animals↗
PubMed1994

Molecular cloning of the complementary DNA and gene that encode mouse brain natriuretic peptide and generation of transgenic mice that overexpress the brain natriuretic peptide gene.

Brain natriuretic peptide (BNP) is a cardiac hormone that occurs predominantly in the ventricle. To study the roles of BNP in chronic cardiovascular regulation, we isolated mouse BNP cDNA and genomic clones, and generated transgenic mice with elevated plasma BNP concentration. The mouse BNP gene was organized into three exons and two introns. Two BNP mRNA species were identified, which were generated by the alternative mRNA splicing. The ventricle was a major site of BNP production in mice. Mouse preproBNP was a 121- (or 120-) residue peptide, and its COOH-terminal 45-residue peptide was the major storage form in the heart. Transgenic mice carrying the human serum amyloid P component/mouse BNP fusion gene were generated so that the hormone expression is targeted to the liver. In the liver of these mice, considerable levels of BNP mRNA and peptide were detected, reaching up to 10-fold greater than in the ventricle. These animals showed 10- to 100-fold increase in plasma BNP concentration accompanied by elevated plasma cyclic GMP concentration, and had significantly lower blood pressure than their nontransgenic littermates. The present study demonstrates that these mice provide a useful model system with which to assess the roles of BNP in cardiovascular regulation and suggests the potential usefulness of BNP as a long-term therapeutic agent.

Alternative Splicing↗
PubMed1993

Characterization of slow postsynaptic K+ current of Aplysia LUQ neurons in culture.

We have characterized the slow inhibitory synaptic connection between an left upper quadrant (LUQ) neuron and neuron L10, L12 or L13 in culture. A slow postsynaptic outward current in the LUQ neuron was elicited by repetitive firing of the co-cultured cholinergic neuron L10 as well as neuron L12 or L13 which were not cholinergic but FMRFamide synthesizing neurons. This outward current was due to an increase in K+ conductance and was relatively insensitive to external application of tetraethylammonium and 4-aminopyridine. We also investigated the effects of injection of a guanosine 5'-triphosphate (GTP) analogue into the LUQ neuron and extracellular application of serotonin and an adenosine 3',5'-cyclic monophosphate (cAMP) analogue on the current. In all the investigated properties, no significant difference was found among neuron L10, L12 and L13 as a presynaptic neuron. The slow postsynaptic current appeared to be virtually identical to the FMRFamide or acetylcholine (ACh)-induced K+ current reported in vivo, which resembled the 'S' current in Aplysia sensory neurons. We performed experiments to see the effect of phenyltrimethylammonium, an ACh antagonist, on the postsynaptic, ACh-, and FMRFamide-induced currents, clearly indicating that the neurotransmitter used in the cultured synapses was not ACh.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1993

Neurotransmitter release from lysophosphatidic acid stimulated PC12 cells: involvement of lysophosphatidic acid receptors.

The significance of phospholipase D in metabolic regulation is being recognized. The products of phospholipase D action are phosphatidic acid and lysophosphatidic acid (LPA). Whether these lipid products exert their effect through plasma membrane receptor-mediated mechanism is not yet clear. In the present study we have shown the presence of specific receptors for LPA in plasma membranes of PC12 pheochromocytoma cells. LPA evoked a transient rise in [Ca2+]i concomitant with formation of IP3. LPA also stimulated dopamine release from PC12 cells. These results indicate that LPA stimulates catecholamine release via specific LPA receptors presumably by activating the IP3 mediated Ca2+ release.

Animals↗
PubMed1993

Information theoretic analysis of action potential trains. I. Analysis of correlation between two neurons.

A crosscorrelational method of action potential trains has been proposed, based on information theory. Two information theoretic quantities, mutual information and channel capacity, were calculated from a pair of action potential trains for detecting a crosscorrelation and estimating synaptic connectivity. The method was compared with conventional ones, using action potential trains obtained by the simulation of a neuron model. This method was shown to have the advantages to more easily find a weak but significant crosscorrelation and to give better estimation of synaptic connectivity independent of the firing probability of a presynaptic neuron.

Action Potentials↗
PubMed1993

Optical recording and information theoretic analysis of Aplysia gill-withdrawal reflex.

A new experimental setup has been devised to perform Aplysia optical recording, the firing of the siphon sensory neurons being precisely controlled. Significant crosscorrelations between the siphon sensory neurons and optically detected neurons were obtained by our information theory-based analysis, and we discussed possible roles of the detected neurons in the gill-withdrawal reflex.

Action Potentials↗
PubMed1992

Data processing for multi-channel optical recording: action potential detection by neural network.

Using a neural network, we have developed a program for fast and precise detection of action potentials (AP) in raw multi-channel optical recording data. The AP detection was performed in two steps: first, peaks were detected in raw optical data, and, second, the peaks were classified by the neural network into APs, noise and undecided peaks. The network was optimized and trained by the backpropagation learning algorithm, employing some thousands of manually classified peaks. The performance of the optimized network was found to be not completely satisfactory, although it was better than the classification by template matching and nearest-neighbor rules. The addition of a signal-to-noise ratio (SNR) of a peak to the network classification improved the classification performance: in comparison with the manual classification results, 96% of manually classified APs were detected. The causes of classification errors were discussed. In spite of the fact that the program required a slight amount of human intervention for undecided peaks, the program could allow mostly automatic AP detection.

Action Potentials↗
PubMed1992

448-detector optical recording system: development and application to Aplysia gill-withdrawal reflex.

The spatial resolution of a fast, multichannel, optical recording apparatus has been improved in an attempt to increase the completeness of optical recordings of neuron activity responsible for the Aplysia gill-withdrawal reflex. We developed a new optical apparatus, increasing the number of pixels to 448. Action potential activity from 168 to 192 neurons could be detected. Hence, the number of optically detected neurons increased about 2.5 times in comparison with a previously used 100- or 124-detector optical apparatus. Because optically detected action potential signals were shown to be due to the cell body of a neuron, it was possible to know its position as well as its approximate size. The distribution of the detected active neurons and those neurons that showed an apparent change in spike frequency to the siphon stimulation were determined.

Action Potentials↗
PubMed1991

Post-translational processing and secretory pathway of human atriopeptin in rat pheochromocytoma cells.

Atriopeptin (AP) is expressed in several tissues with each tissue capable of specific differences in processing of the prohormone (pro-AP) to mature low molecular forms of the peptide. Since pro-AP has low biological activity, processing into mature AP is a critical activation event. This observation prompted us to study whether granule storage or regulated secretion of AP is essential for cleavage of mature peptide. We examined the processing of AP in adrenal medulla derived cells, using the rat pheochromocytoma cell line (PC12 cell) stably transfected with a genomic human AP DNA in the presence and absence of nerve growth factor (NGF), and also examined the mechanism of AP secretion and compared the results with those obtained using transfected chinese hamster ovary cells (CHO cells). The amount of prohormone was 5-10 fold higher than that of low molecular form of AP in the transfected PC12 cells. This ratio was essentially unchanged in differentiated PC12 cells after NGF treatment of the cells. Potassium depolarization of the transfected PC12 cells caused a 5-fold increase in AP release into the medium primarily as the intact prohormone. On the other hand, transfected CHO cells only exhibited constitutive AP release which is non-response to depolarization. These results suggest that the AP prohormone is sorted into secretory granules as the prohormone in PC12 cells and undergoes regulated release in response to depolarization indicating granule storage or release is not the critical determinant of AP prohormone cleavage.

Adrenal Gland Neoplasms↗
PubMed1991

Pathophysiological role of augmented atrial natriuretic polypeptide gene expression in DOCA-salt hypertension. Effects of atrial natriuretic polypeptide monoclonal antibody.

To elucidate the pathophysiological significance of endogenous atrial natriuretic polypeptide (ANP) in hypertension, we investigated the biosynthesis and secretion of ANP in deoxycorticosterone acetate (DOCA)-salt hypertensive rats and also examined the effect of passive immunization with monoclonal antibody raised against alpha-rat ANP on the development of hypertension in DOCA-salt rats. The plasma ANP level in DOCA-salt rats was significantly elevated in comparison to control rats. While the atrial ANP concentration in DOCA-salt rats was not significantly altered, the atrial level of ANPmRNA in DOCA-salt rats was two-fold higher than that in control rats. These results suggest the augmented biosynthesis of ANP in the atrium and the oversecretion of ANP from the heart in DOCA-salt rats. The levels of ANP and ANPmRNA in the ventricle of DOCA-salt rats exhibited significant increases, compared with those in control rats, suggesting the induction of ANP gene expression in the ventricle of DOCA-salt hypertensive rats under pre/after overload. Weekly intravenous administrations of monoclonal antibody with high affinity for alpha-rat ANP significantly augmented the rise in blood pressure of DOCA-salt rats. These results support the hypothesis that the augmented secretion of ANP is one of the defensive mechanisms to counteract high arterial pressure in this model of hypertension.

Animals↗
PubMed1990

Isolation and sequence determination of human brain natriuretic peptide in human atrium.

We isolated human brain natriuretic peptide (human BNP) from the human atrium. Sequence analysis has revealed that it is a 32-amino-acid peptide with the sequence S-P-K-M-V-Q-G-S-G-C-F-G-R-K-M-D-R-I-S-S-S-S-G-L-G-C-K-V-L-R-R-H, which is identical to the C-terminal sequence (77-108) of the human BNP precursor deduced from the cDNA sequence. The sequence of human BNP (77-108) is preceded by Pro75-Arg76 in the human BNP precursor, which is the same processing signal as Pro97-Arg98 of the precursor of atrial natriuretic peptide (ANP). The processing of the BNP precursor occurs in the cardiocyte, although that of the ANP precursor in the cardiocyte is unclear at present.

Amino Acid Sequence↗
PubMed1990

Alternative mechanisms for atriopeptin prohormone processing by isolated perfused rat hearts.

The isolated perfused rat heart releases atriopeptin-28 [AP28 (ANF99-126)], whereas the storage form of AP in the heart is the intact prohormone AP126 (ANF1-126). Right atrial stretch or phenylephrine (5 x 10(-5) M) stimulated the release of AP28. The processing of the prohormone during stretch was inhibited by infusion of the protease inhibitor aprotinin, resulting in the appearance of intact AP126 in the cardiac effluent. Other protease inhibitors including p-aminobenzamidine and soybean trypsin inhibitor did not alter prohormone processing by the isolated heart subjected to stretch. In contrast, aprotinin did not block the prohormone processing induced by phenylephrine. Ca+(+)-free medium markedly inhibited prohormone processing during stretch without a significant effect on AP release, whereas phenylephrine-stimulated AP release was completely suppressed by Ca+(+)-free medium. Exogenous AP126 could be cleaved by isolated rat hearts perfused either with Krebs-Henseleit solution or with Ca+(+)-free medium. However, amino acid sequence analysis revealed that the prohormone cleavage in Ca+(+)-free medium occurred at sites other than between Arg98 and Ser99 and that the resultant low molecular weight APs were not AP28. These findings suggest: 1) the characteristics of the enzyme(s) involved in the processing of AP prohormone in isolated perfused rat hearts are different from the described properties of purified enzymes; 2) in isolated perfused rat hearts the specific AP processing enzyme is Ca++ dependent, whereas nonspecific cleavage does not necessarily require Ca++ and 3) two independent AP processing pathways differentially activated by mechanical (stretch) and pharmacologic (alpha 1-adrenergic agonist) stimuli exist.

Animals↗
PubMed1989

A study on limulus amebocyte lysate (LAL) reactive material derived from dialyzers.

The amebocytes of horseshoe crab (Limulus) hemolymph contain a coagulation system highly sensitive to bacterial endotoxins. Limulus amebocyte lysate (LAL) reactive material derived from cuproammonium rayon membranes, however, is not an endotoxin and acts upon the alternative pathway in the coagulation cascade found in Limulus amebocyte lysate. This study confirmed these facts by using the coagulation system of Limulus without factor G, which is a substrate of the alternative pathway. LAL reactive material lingered in the circulation for a relatively long time. In acute hemodialysis, its plasma concentration increased by an average of 100 pg/ml with each dialysis and eventually reached a plateau of approximately 300 pg/ml. In patients with chronic renal failure under regular hemodialysis, the mean level of LAL reactive material was 330.0 +/- 8.0 pg/ml before hemodialysis which increased by 70.6 +/- 20.7 pg/ml after four hours of hemodialysis.

Acute Kidney Injury↗
PubMed1989

Assessment of the early cellular membrane response to live Escherichia coli bacteremia.

Alterations in skeletal muscle cellular function during septic shock have been previously demonstrated. However, whether these alterations represent a specific response to the septic state or are simply a consequence of low flow is uncertain. The present study was designed to evaluate the cellular membrane response to the early bacteremic state, prior to the onset of hemodynamic compromise. A clinically relevant model of sepsis was achieved in six mongrel dogs by intraarterial infusion of live Escherichia coli organisms and concurrent volume loading with lactated Ringer's solution. Four sham-treated dogs served as controls. Forty-eight hours after induction of sepsis, resting transmembrane potential (Em) was measured in a hindlimb adductor muscle. Contemporaneous muscle biopsy was performed for determination of transmembrane water and electrolyte distribution. The bacteremic state was associated with depolarization of Em to -79.7 +/- 1.2 mV from a basal value of -89.3 +/- 0.2 mV (P less than 0.01), while Em in the sham-treated group remained unchanged over the same time course. In addition, there was a significant increase in the calculated intracellular Na+ and Cl- concentrations in the septic group (P less than 0.02), while intracellular K+ was unchanged. These data are consistent with a selective increase in cell membrane permeability to Na+ and indicate that cellular alterations in skeletal muscle occur early in the septic course, in the absence of hemodynamic compromise. This alteration in membrane permeability appears to be common to cells of disparate organ systems in response to sepsis, and may represent a protean manifestation of cellular injury.

Adenosine Triphosphate↗