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Biomedical subjects

T Shiga

Publications and source records attributed to T Shiga.

At least 109 records · Page 6Linked to original sources
PubMed1994

Biochemical characterization and immunolocalization of SC2 protein: SC2 protein is indistinguishable from the cell adhesion molecule axonin-1.

SC2 is a monoclonal antibody that was previously shown to recognize a subset of neurons in the developing nervous system of the chick. We have now used the SC2 monoclonal antibody to purify from chick embryo brain membranes a glycoprotein that migrates at approximately 125 kDa on SDS/PAGE. The size of this protein and its distribution pattern in the spinal cord are similar to that observed for axonin-1. A polyclonal anti-axonin-1 antibody R26 specifically reacted with the SC2 protein from brain. This antibody, as well as polyclonal antibody (369) against purified SC2 protein, reacted with 115-130 kDa proteins in vitreous humor, a rich source of axonin-1, and with similar sized proteins precipitated from vitreous humor by the 369, and SC2 antibodies. Treatment of SC2 protein isolated from chick brain membranes with PI-PLC indicated that it contains a glycophosphatidylinositol (GPI) moiety. Co-aggregation experiments using Covaspheres with covalently bound proteins indicated that SC2 protein binds heterophilically to Ng-CAM. Immunohistochemical analysis of chick embryos showed that SC2 protein is abundant in the sensory nerve bundles of both the central and peripheral nervous systems during development. Its expression was restricted and it was specifically localized in the dorsal funiculus of the spinal cord, as well as in olfactory, retinal, trigeminal, vestibulocochlear, glossopharyngeal and vagal nerve fibers. The biochemical and immunohistochemical data show that SC2 protein is axonin-1, and the immunolocalization studies support the hypothesis that SC2 protein may play a role during development of particular fiber systems by interacting with other cell adhesion molecules such as Ng-CAM.

Animals↗
PubMed1994

Direct proof of nitric oxide formation from a nitrovasodilator metabolised by erythrocytes.

When 15N-isosorbide dinitrate was injected into rats, the venous blood showed a 2-line hyperfine structure in the electron spin resonance (ESR) spectra of NO hemoglobin (HbNO), proving generation of 15N-NO. When human blood was mixed with 15N-isosorbide dinitrate anaerobically, ESR spectra showed initially 14N-HbNO, which was then overwhelmed with the increased 15N-HbNO. With deoxygenation of the blood of another 4 male donors without addition of isosorbide dinitrate, two showed 14N-HbNO, but others did not, suggesting varied amount of NO-precursers, nitrosothiols, in human blood. Neither N-ethylmaleimide nor S-hexylglutathione, a glutathione-S-transferase inhibitor, inhibited the formation of UbNO in the hemolysate mixed anaerobically with isosorbide dinitrite.

Adult↗
PubMed1994

Nitrosyl hemoglobin production during reperfusion after focal cerebral ischemia in rats.

We first detected a definite nitrosyl hemoglobin (HbNO) signal in the jugular blood by electron spin resonance spectroscopy during early reperfusion after cerebral ischemia. A distinct three-line hyperfine structure, characteristic to HbNO, was demonstrated at 30 min of recirculation after 2 h of middle cerebral artery occlusion in rats. Only a weak HbNO signal was observed in animals with 2 h sustained ischemia or with sham operation. The present findings suggest that reperfusion after cerebral ischemia facilitates nitric oxide generation in the brain, which leads to the increased nitrosylation of erythrocyte hemoglobin in the cerebral circulating blood.

Animals↗
PubMed1994

Electron spin resonance signals of non-heme iron as an indicator of ischemia-reperfusion injury of the liver.

Although many different methods have been proposed to assess the viability of preserved or reperfused liver, none of them are definitive. In this study, we investigated the usefulness of electron spin resonance (ESR) spectrometry in the rat liver ischemia model. Ischemia was induced in Wistar rats weighing 250-300 g by clamping the portal triad. At 15, 30, 60, or 90 min after the clamping, the liver was reperfused by removing the clamp. Liver specimens obtained before and after the clamping and also 30 min after reperfusion were frozen with liquid nitrogen and analyzed at 140K by ESR spectrometry. Two significant signals of g-values of 2.0 and 1.96 were observed with the fresh liver. The former was thought to be a mixture of CoQ, flavin, and succinate radicals. The intensity of this signal did not change throughout the experimental period. The latter was regarded as the signal from non-heme irons of mitochondria. The intensity of this signal decreased as the ischemic time became longer (the ratio to the signal intensity of the fresh liver was 0.69 +/- 0.19, 0.22 +/- 0.08, 0.20 +/- 0.05, and 0.18 +/- 0.09 at the end of 15, 30, 60, and 90 min of ischemia, respectively). After reperfusion, each ratio recovered to 0.95 +/- 0.12, 0.77 +/- 0.06, 0.56 +/- 0.15, and 0.37 +/- 0.20, respectively. This suggests that detectable signals with Fe(II)-Fe(III) decreased and became undetectable as the reduced form of non-heme irons under the anoxic state. Then, after reperfusion, the reduced form of non-heme irons decreased and the oxidized form increased. Incomplete recovery was thought to be due to decrease in the viability or function of liver cells. ATP and energy charge had the same tendency as the non-heme iron signal observed with ESR. There was a significant correlation between the non-heme iron signal and energy charge (y = 0.73x + 0.32, r = 0.78, P < 0.001), demonstrating that the signal intensity reflects the viability or function of liver cells. This study suggests that the signal from non-heme irons detected by ESR can be a good parameter of the metabolic state of the liver in ischemia and reperfusion. This method is simple and quick and should be applicable in clinical liver transplantation.

Adenosine Diphosphate↗
PubMed1994

Comparison of the pharmacokinetics, pharmacodynamics, and safety of oral (Catapres) and transdermal (M-5041T) clonidine in healthy subjects.

The pharmacokinetic as well as pharmacodynamic properties of a transdermal clonidine, M-5041T (M) and its safety were compared with those of oral clonidine, Catapres (Nippon Boehringer Ingelheim, Hyogo, Japan). One patch of M containing 6 mg of clonidine was applied on the right chest for 3 days or one tablet of Catapres (.075 mg) was given orally every 12 hours for 3 days in eight healthy subjects. The study was conducted by a crossover design with 14 to 16 days' interval between the cross-over. Blood and urine samples for clonidine concentration were obtained, and blood pressure (BP) was measured for a 168-hour period after application of M and for a 96-hour period after initiation of Catapres therapy. Plasma concentration of clonidine increased gradually after application of M and decreased gradually after removal, whereas this parameter increased rapidly during the absorption phase and decreased rapidly in the elimination phase after each dosage of Catapres. Elimination half-life of clonidine after removal of M was significantly greater than that after the final dosage of Catapres. No significant difference was observed in maximum plasma concentration or area under the plasma concentration-time curve between the two trials. The BP lowering effects of M and Catapres did not differ significantly. Adverse symptoms occurred more frequently during Catapres therapy than during treatment with M. Most of these symptoms were observed when plasma clonidine concentration was relatively higher in each trial. These results suggest that M is effective for the treatment of hypertension with a lower incidence of adverse symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Cutaneous↗
PubMed1994

Renal clearance of lomefloxacin is decreased by furosemide.

The interaction between lomefloxacin, a new quinolone, and furosemide, a loop diuretic, has been examined. Oral lomefloxacin 200 mg and furosemide 40 mg were given together or separately to 8 healthy subjects, and blood and urine samples were obtained over the following 12 h. The plasma concentrations of lomefloxacin following coadministration with furosemide were higher than after lomefloxacin alone and its AUC was increased, and its total and renal clearances were decreased. No change in the pharmacokinetics of furosemide was found after coadministration of lomefloxacin. As quinolones and furosemide are reported to be excreted in urine by the renal tubular anion transport system, the present results suggest that the renal tubular secretion of lomefloxacin is diminished by furosemide. It is not clear whether this pharmacokinetic interaction might be clinically important.

Adult↗
PubMed1994

Effect of interferon-gamma on nitric oxide hemoglobin production in endotoxin-treated rats and its synergism with interleukin 1 or tumor necrosis factor.

We studied the in vivo effect of interferon-gamma (IFN-gamma) on nitric oxide (NO) generation. ESR spectra of nitric oxide hemoglobin (HbNO) appeared after a lag time of 2h in the blood of rats treated with Escherichia coli lipopolysaccharide (LPS). IFN-gamma enhanced LPS-induced HbNO formation in rats without modifying the time lag, although IFN-gamma alone did not induce HbNO formation. The plasma nitrate concentration was approximately one order of magnitude higher than the HbNO concentration. On treatment with LPS alone, the amount of tumor necrosis factor (TNF) released decreased after 2 h. Simultaneous addition of IFN-gamma and LPS increased TNF release for at least 8 h. Interleukin 1 (IL-1) release was detected only at 2 h in both groups. We also investigated the in vivo interactions of these cytokines. TNF plus IL-1 induced the greatest HbNO generation, followed by TNF plus IFN-gamma, and then IL-1 plus IFN-gamma. These results suggest that increase of TNF release by IFN-gamma plays a key role in NO generation in LPS-treated rats.

Animals↗
PubMed1994

Intravital microreflectometry of individual pial vessels and capillary region of rat.

A microscopic reflectance spectrophotometer was constructed to obtain the spectra of single pial vessels and of a region containing only capillaries (capillary region). The difference in the oxygen saturation (SO2) of hemoglobin between the regional arteriole and venule [R(A - V)] and that between the regional arteriole or capillaries [R(A - C)] were calculated. The reduction of cytochrome aa3 was also estimated in the capillary region. This method was applied to the brain surface of spontaneously breathing rats subjected to hypoxic and anemic hypoxia. On decreasing the inhaled O2 from 100 to 15%, elevation of R(A - V) and R(A - C) with slight arteriolar dilatation (though statistically not significant) was observed. Below 10% O2 (especially at 4 and 3% O2), the R(A - V) and R(A - C) decreased in spite of significant arteriolar dilatation with progressive reduction of cytochrome aa3, indicating suppression of oxygen transport to mitochondria. In the case of hemodilution down to 37% hematocrit (Ht), elevation of R(A - V) and R(A - C) occurred with a slight tendency toward arteriolar dilatation. Below 32% Ht, the R(A - V) decreased but the R(A - C) remained steady, while reduction of cytochrome aa3 progressed. Altogether, the SO2 in the capillary region decreased and the reduction of cytochrome aa3 progressed with the decline of arteriolar O2 supply in both hypoxic and anemic hypoxia.

Anemia↗
PubMed1994

Elevation of plasma nitric oxide end products during focal cerebral ischemia and reperfusion in the rat.

We investigated the alterations in the stable end products of nitric oxide, i.e., nitrate and nitrite, in the plasma during and after rat focal cerebral ischemia by an automated procedure based on the Griess reaction. At 2 h of middle cerebral artery (MCA) occlusion, plasma nitrate/nitrite levels were significantly higher (53 +/- 8 microM, mean +/- SD, n = 5, p < 0.05) than in rats with sham operation (36 +/- 9 microM, n = 5), and were mildly elevated at 4 h of MCA occlusion (42 +/- 9 microM, n = 5, n.s.). At 30 min of reperfusion after 2 h of MCA occlusion, plasma nitrate/nitrite levels were more markedly elevated (72 +/- 7 microM, n = 5, p < 0.01 vs. sham operation), but were moderately elevated at 2 h of reperfusion after 2 h of MCA occlusion (61 +/- 10 microM, n = 5, p < 0.05). Plasma nitrite levels were not changed during these experimental periods. Administration of 20 mg/kg of NG-nitro-L-arginine methyl ester (L-NAME) significantly decreased plasma nitrate/nitrite as well as nitrite at 30 min of reperfusion after 2 h of MCA occlusion (n = 5), but 2 mg/kg of L-NAME did not (n = 3). The effect of 20 mg/kg of L-NAME on plasma nitric oxide end products was reversed by the simultaneous administration of 200 mg/kg of L-arginine (n = 3), but not D-arginine (n = 3). The present study suggests that the L-arginine-nitric oxide pathway is activated during acute cerebral ischemia and reperfusion.

Animals↗
PubMed1994

Microspectroscopic measurement of the optical properties of rat liver in the visible region.

Microspectroscopy is used to investigate optical properties of haemoglobin-free perfused rat liver. Visible spectra of 20 microns diameter spot size were measured in transmission and/or reflection modes as a function of the thickness (< 1200 microns) of the liver-edge. Optical density (OD) in transmission mode increased with the increasing liver thickness, whereas in reflection mode OD decreased but became almost constant above a certain thickness (c.600 microns) of the liver. The Kubelka-Munk (KM) two-flux model, with a minor modification, was applied successfully to the analysis of the changes in OD as a function of the thickness. This approach estimates the KM absorption coefficient (EKM), KM scattering coefficient (SKM) and effective penetration depth (delta eff) of the liver. The optical properties were similar to reported values, obtained with different methods.

Animals↗
PubMed1994

ESR spectral transition by arteriovenous cycle in nitric oxide hemoglobin of cytokine-treated rats.

Nitric oxide (NO) generation was induced in rats by Escherichia coli lipopolysaccharide (LPS) as detected by electron spin resonance (ESR) signals of NO hemoglobin (HbNO). However, there were inconsistencies in ESR spectral shape among them. We have therefore carried out a systematic study to clarify the in vivo spectral changes. First, the spectra of the alpha-NO heme species had the distinct three-line hyperfine structure in venous blood but not in arterial blood in all rats treated with tumor necrosis factor, interleukin-1, and/or LPS, and methemoglobin was not detected at the g = 6 (high-spin methemoglobin) region. Second, when the treated rats died, the three-line hyperfine structure was very distinct even in arterial blood. Third, even if HbNO was formed by injection of nitrite to rats, the three-line hyperfine structure of HbNO in venous blood was more marked than that in arterial blood, independent of the appearance of the methemoglobin signal. Fourth, an ex vivo study using whole blood demonstrated that the three-line hyperfine structure intensified lineally when O2 saturation of hemoglobin decreased but disappeared on reoxygenation of hemoglobin. These results directly demonstrate in vivo quaternary structural transition of the hemoglobin tetramer from the high-affinity state in the arterial cycle to the low-affinity state in the venous cycle. The transition makes the diverse ESR spectra of HbNO in vivo.

Animals↗
PubMed1994

Assessment of rate of O2 release from single hepatic sinusoids of rats.

Characteristics of O2 release from single hepatic sinusoids are described in relation to the sinusoidal O2 inflow for the first time. Microspectroscopic measurement of the rate of O2 release (RO2) from single sinusoids to surrounding hepatocytes was carried out at the edge of the liver of anesthetized rats. The oxyhemoglobin inflow ([HbO2] inflow) into sinusoids, which is a product of sinusoidal blood flow rate and inflowing oxyhemoglobin concentration ([HbO2]), was varied by exchange transfusion of blood with physiological saline. 1) RO2 from single hepatic sinusoids of control rats was fairly constant [0.66 +/- 0.14 (SD) nmol.cm-2.s-1, with 18 sinusoids of 9 rats] over a wide range of [HbO2] inflow (50-200 fmol/s). 2) In the cases of mild anemia, [HbO2] inflow scarcely decreased but RO2 increased, probably because of the increased metabolism of hepatocytes. 3) In the cases of severe anemia, [HbO2] inflow decreased below 50 fmol/s and RO2 decreased accordingly. 4) In all cases no difference was observed between the RO2 values obtained from periportal zone and those from pericentral zone. These results are discussed on the bases of the vascular structure and function of hepatic sinusoids and on the animal model of hemorrhagic shock.

Acute Disease↗
PubMed1994

Reactive oxygen species involved in phenazine-methosulfate-induced rat lens opacification. An experimental model of cataract.

The excised rat crystalline lens opacified when incubated aerobically with phenazine methosulfate, but no opacification was observed under anaerobic conditions. Morphological studies revealed development of opacification in the cortex. The opacification resembled that often seen in the early period of senile cataract as well as in naphthalene-induced and UV cataract. Both an increase in hydration and in electrolyte imbalance accompanied this opacification. Na,K-ATPase activity of the opacified lens was found to decrease. In order to investigate if activated oxygen is involved in these processes, we conducted an electron spin resonance study by means of a spin trapping technique. When the lens homogate was incubated with phenazine methosulfate, OH radicals were generated under aerobic but not under anaerobic conditions. Reduced pyridine nucleotides must be involved in the process, because the mixture of nicotinamide adenine dinucleotide phosphate [NAD(P)] and phenazine methosulfate did not generate OH radicals, but the mixture of NAD(P)H and phenazine methosulfate generates OH radicals, indicating that reduced phenazine methosulfate was involved in the OH radical generation. Probably, the generated OH radicals inactivated Na,K-ATPase residing in the epithelium of the lens, which eventually caused opacification of the lens. The present experiment system may be used for the elucidation of lens opacification (cataract) involved with reactive oxygen species.

Animals↗
PubMed1994

Administration time-dependent change in the effect of spironolactone in rats.

The present study was undertaken to examine whether the natriuretic effect of spironolactone, a competitive antagonist of mineralocorticoid, varies with its time of administration. Wistar rat maintained under the condition of light from 7 hr to 19 hr were divided into two groups. The first group had a bilateral adrenalectomy and received a 50-mg deoxycorticosterone acetate (DOCA) tablet intraperitoneally (DOCA group). The second group had a sham operation (control group). Spironolactone (50 mg/kg) was given orally at 12 hr or 24 hr, and the 8-hr urine was collected. At the end of the experiment, the blood sample for measurement of aldosterone was obtained at 12 hr and 24 hr in the control group. The natriuretic effect of spironolactone in the 24 hr-trial was significantly greater than that of the 12 hr-trial in the control group. However, such a time-dependent difference was diminished and did not reach statistical significance in the DOCA group. The plasma aldosterone concentration at 24 hr was significantly higher than that at 12 hr in the control group. These results suggest that the natriuretic effect of spironolactone varies with its time of administration. Daily variation in mineralocorticoid activity might be involved in this chronopharmacological phenomenon of spironolactone.

Administration, Oral↗
PubMed1994

[High dose epidural fentanyl suppresses the increase in cortisol levels during open chest surgery].

We investigated the effect of high dose epidural fentanyl (HEF) on plasma levels of epinephrine (E), norepinephrine (NE) and cortisol (C) during open chest surgery (OCS). Twenty five patients undergoing open chest surgery was divided randomly into two groups. Thirteen patients had HEF (F-Group) and the rest of 12 patients had epidural mepivacaine (M-Group). Epidural puncture (Th5-6) and catheterization were performed before anesthetic induction. Anesthesia was induced with thiamylal (5 mg.kg-1) and trachea was intubated after injection of vecuronium (0.1 mg.kg-1). Anesthesia was maintained with 50% N2O and isoflurane as needed. After 0.2 ml.kg-1 of fentanyl was injected through the epidural catheter, fentanyl was infused continuously (0.05 mg.h-1) in F-Group. In M-Group, after 0.2 ml.kg-1 of 1% mepivacaine was injected through the epidural catheter, 1% mepivacaine was infused continuously (10 ml.h-1). For the measurement of E, NE and C, blood samples were collected at following points; 1) before anesthetic induction, 2) before incision, 3) during open chest and 4) in the recovery room. In both groups, E and NE levels did not change significantly. In F-Group, plasma C levels decreased significantly when chest was opened. C levels in F-Group, were significantly lower than in M-Group before incision and during open chest.

Aged↗
PubMed1994

[An evaluation of the hemodynamics in metastatic liver tumor by using ultrasound color Doppler flow mapping examination].

Eighty-one patients with metastatic liver tumors were studied by ultrasound color Doppler flow mapping examination. Primary origins consisted of gastric (19 cases), colorectal (40 cases), breast (7 cases), pancreatic (3 cases), gallbladder (3 cases) cancers and the others (9 cases). Metastatic lesions originated from breast, gastric and colorectal cancers had higher detection rates, however no blood flow could be observed within metastatic liver cancers from pancreatic and gallbladder cancers. There were no differences among the maximum blood flow velocity (Vmax), the resistance index (RI) and the pulsatile index (PI) in various metastatic liver tumors. In case of colorectal cancers, metastatic lesions originated from moderately differentiated adenocarcinoma had significantly lower RI (p < 0.05) and PI (p < 0.01) than that from well differentiated adenocarcinoma. In conclusion, ultrasound color Doppler flow mapping examination is a useful method for evaluation of the blood flow within metastatic liver tumors and could offer the histological differentiation of the primary origins, in case of metastatic liver cancers originated from colorectal cancers.

Adult↗