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Biomedical subjects

Y Shimada

Publications and source records attributed to Y Shimada.

At least 487 records · Page 27Linked to original sources
PubMed1992

Spatial relationship of nebulin relative to other myofibrillar proteins during myogenesis in embryonic chick skeletal muscle cells in vitro.

The developmental expression of nebulin was studied in embryonic chick skeletal muscle cells in vitro by means of immunofluorescence microscopy. Initially nebulin appeared homogeneously or in a punctate form in the cytoplasm, and then it was assembled into I-Z-I-like complexes containing actin and alpha-actinin but not myosin and connectin (titin). Striated patterns of nebulin ('singlets') in myofibrils appeared simultaneously with those of alpha-actinin (Z-bands), myosin (A-bands) and connectin ('doublets'), but earlier than those of actin. After actin striations were formed as myofibrils matured, each nebulin band started to exhibit 'droplets'. The delayed development of nebulin compared to the I-Z-I brush formation and the myofibril maturation seems to indicate that this giant myofibrillar protein is unnecessary for both the initial (formation of I-Z-I-like structures) and the subsequent (regular alignment of myofibrils) phases of myofibrillogenesis.

Animals↗
PubMed1992

The sequential change of serum 2',5' oligoadenylate synthetase in different infectious patterns of duck hepatitis B virus in ducks in experimental transmission.

Duck hepatitis B virus (DHBV) shows clear age-dependent infectious patterns like that of Hepatitis B virus, and many factors have been assumed to have a role in the persistence of the infection. In the present study, the activities of the interferon-induced enzyme 2',5' oligoadenylate synthetase (2,5AS) were observed sequentially in the serum of ducks experimentally infected with DHBV on posthatch days 1, 7 and 14. These were compared with the infectious pattern to investigate whether the endogenous interferon response after infection in ducks of different ages has a major role in its determination. The infectious pattern of DHBV in 1-day-old ducks was persistent without hepatitis and the others were transient with hepatitis. Persistently infected ducks showed significantly lower activities of 2,5AS compared with those with transient hepatitis, which resulted in a rapid elimination of DHBV. Although 1-day-old ducks showed significantly high 2,5AS compared with non-infected ducks, interferon response alone appeared to be insufficient for the elimination of DHBV. The immune response seemed necessary for the complete elimination of DHBV by way of evoking hepatitis and stimulating more interferon response during the usual infectious course. The interferon system alone did not seem to have a critical role in determining the infectious pattern. Other factors, including the immune response to the virus, seemed to have a major role in this problem.

2',5'-Oligoadenylate Synthetase↗
PubMed1992

Regional differences in skin blood flow and temperature during total spinal anaesthesia.

Three patients were studied to determine the changes in regional skin temperature and blood flow during extensive sympathetic blockade following total spinal anaesthesia (TSA). Skin temperature was measured at the right upper arm, the right anterior chest at the nipple level, the right hand and the foot, using infrared thermography. Skin blood flow of the right upper arm (C6 area) was measured with a laser Doppler flowmeter. The temperature of the truncal area, arm and leg decreased by 1 degree C following TSA, whereas the temperature of the hand and foot increased by 3 degrees C. The mean blood flow in three patients decreased to 26.1, 61.4, 51.7% of the control values 15 min after TSA. Our results indicate that extensive sympathetic nervous blockade during total spinal anaesthesia induces regional different changes in skin temperature and decrease in truncal skin blood flow.

Anesthesia, Spinal↗
PubMed1992

Prostaglandin E1 and carbon dioxide reactivity during cerebral aneurysm surgery.

The purpose of this study was to evaluate the effect of prostaglandin E1 (PGE1) on CO2 reactivity during cerebral aneurysm surgery in 37 patients under neuroleptoanaesthesia (NLA). The patients were divided into two groups based on the timing of surgery (A: late surgery B: early surgery). In the early surgery group, aneurysm surgery was performed within three days of subarachnoid haemorrhage (SAH) and in the late surgery group surgery was performed more than four days after SAH. Presurgical neurological status was worse in the early surgery group than in the late surgery group (P less than 0.01). Local cerebral blood flow (LCBF) measurements were made using a thermal gradient blood flow meter. Hypotension was induced by PGE1 administration at an initial dose of 0.1 micrograms.kg-1.min-1 and adjusted to maintain the mean arterial pressure (MAP) at about 70 mmHg. The CO2 reactivity was calculated by the % change in LCBF divided by the change in PaCO2 (% delta LCBF/delta PaCO2 (%.mmHg-1)). LCBF, heart rate and mean arterial blood pressure were measured during and after PGE1 infusion. Carbon dioxide reactivity was measured before, during and after PGE1 administration. The LCBF did not change throughout the study but CO2 reactivity was greater in Group A (before hypotension: 2.74 +/- 0.85 %.mmHg-1, during hypotension: 2.54 +/- 0.73 % .mmHg-1, after hypotension: 2.59 +/- 1.17 %.mmHg-1) than in group B (before hypotension: 1.54 +/- 0.57%.mmHg-1, during hypotension: 1.56 +/- 0.59 %.mmHg-1, after hypotension: 1.49 +/- 0.42%.mmHg-1) (P less than 0.01). Outcome which was graded by Glasgow Outcome Scale at discharge, was better in Group A (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Effect of aging on macrophage adherence to extracellular matrix proteins.

Fibronectin, type I, type IV and type V collagens were compared for their abilities to promote mouse peritoneal resident macrophage adherence and the effect of aging on macrophage adhesion to these matrix proteins was examined. Adherence of macrophages to fibronectin was remarkable and more than 5-fold compared to type I, type IV or type V collagens. Adherence of macrophages to fibronectin and type I collagen increased during aging. However, no age-related changes were observed in macrophage adherence to type IV and type V collagens. The percent of inhibition of macrophage adherence to fibronectin by arginine-glycine-aspartic acid-serine (RGDS) peptide (58.1 +/- 2.7%) was significantly (P < 0.01) higher than that in cells from young mice (23.1 +/- 5.7%). These data suggest that macrophage attach preferentially to fibronectin and that the ability of macrophage to attach to fibronectin increases during aging. The age-related increase in macrophage attachment to fibronectin is related to the concentration of cell surface receptors of macrophage which recognize RGDS sequence within fibronectin during aging. Adherence of macrophage to fibronectin implies retention of macrophages in subendothelial space. Age-related increase in macrophage ability to attach to fibronectin may be related to atherogenesis during aging.

Aging↗
PubMed1992

Effects of fentanyl-diazepam-pancuronium anesthesia on heart rate variability: a spectral analysis.

The effects of induction of anesthesia with fentanyl, 62.1 +/- 7.9 micrograms/kg, diazepam, 0.21 +/- 0.08 mg/kg, and pancuronium on beat-to-beat heart rate variations were studied in seven patients undergoing cardiac surgery. Spectral analysis was used to determine the intensity of the variations in each of the two main frequency bands in which variations are known to occur: (1) high-frequency band, mediated by the parasympathetic nervous system, at the frequency band of respiration, and (2) the low-frequency band, mediated by both sympathetic and parasympathetic nervous systems, at 0.04-0.12 Hz. Both the mean low- and high-frequency band areas were significantly decreased after induction of anesthesia. The ratio of high-to-low frequency band areas increased significantly after induction of anesthesia, from 45% to 62% (P less than 0.05). These results suggest that fentanyl-diazepam-pancuronium anesthesia decreases total autonomic nervous system activity and alters the balance between parasympathetic and sympathetic activities. Thus, spectral analysis of heart rate variations during anesthesia may provide a quantitative measure of assessing the activity of the autonomic nervous system.

Adult↗
PubMed1992

Purification and characterization of a novel thermostable lipase from Pseudomonas cepacia.

A thermostable lipase from Pseudomonas cepacia has been purified to homogeneity as judged by SDS-PAGE and isoelectric focusing. The purification included treatment of the culture supernatant with acrinol, hydrophobic interaction chromatography, and gel filtration. The enzyme was a monomeric protein with M(r) of 36,500 and pI of 5.1. The optimal pH at 50 degrees C and optimal temperature at pH 6.5 were 5.5-6.5 and 55-60 degrees C, respectively, when olive oil was used as the substrate. Simple triglycerides of short and middle chain fatty acids (C < or = 12) were the preferred substrates over those of long chain fatty acids. The enzyme cleaved all the ester bonds of triolein, with some preference for the 1,3-ester bonds. The enzyme retained all its activity even after incubation at 75 degrees C (pH 6.5) for 30 min. Further, the activity was not impaired during 21 h storage at pH 6.5 in 40% water-miscible solvents including methanol, ethanol, acetone, acetonitrile, dimethylformamide, dimethylsulfoxide, and dioxane. The addition of dimethylsulfoxide or acetone to the assay mixture in the range of 0-35% stimulated the enzyme, whereas benzene or n-hexane had an inhibitory effect. These properties together with the N-terminal amino acid sequence confirmed that the enzyme differs from the known Pseudomonas sp. lipases.

Amino Acid Sequence↗
PubMed1992

Hepatic venous hemoglobin oxygen saturation predicts liver dysfunction after hepatectomy.

A fiberoptic flow-directed catheter inserted into the hepatic vein continuously measures hepatic venous oxygen hemoglobin saturation (ShvO2). This study determined whether intraoperatively measured ShvO2 could predict postoperative serum activities of aminotransferases and patient outcome in 83 patients undergoing hepatectomy. The duration of intraoperative ShvO2 less than or equal to 10, 20, 30, 40, and 50% was calculated in each case. Significant increases in postoperative serum aminotransferases were associated with more than 1, 11, 31, 51, and 181 min of duration of ShvO2 less than or equal to 10, 20, 30, 40, and 50%, respectively. The incidence of postoperative liver failure significantly increased when the duration of ShvO2 less than or equal to 20, 30, and 40% exceeded 11, 31, and 51 min, respectively. The mortality from liver failure was significantly higher when the duration of ShvO2 less than or equal to 30 and 40% exceeded 31 and 51 min, respectively. Therefore, intraoperative monitoring of ShvO2 may predict not only the increase in postoperative serum aminotransferases but also patient outcome in terms of postoperative liver failure after hepatectomy.

Adult↗
PubMed1992

The effect of dobutamine on hepatic blood flow and oxygen supply-uptake ratio during enflurane nitrous oxide anesthesia in humans undergoing liver resection.

Liver surgery is often accompanied by hepatic hypoperfusion and hypoxia, and it is controversial whether catecholamines increase hepatic blood flow and oxygen supply. The effects of 3 micrograms.kg-1.min-1 dobutamine on hepatic circulation and oxygen balance were examined in patients anesthetized with enflurane, nitrous oxide, and oxygen for liver surgery. Dobutamine did not cause a significant increase in hepatic arterial blood flow. However, total hepatic blood flow and portal venous blood flow were increased, resulting in an increase in hepatic oxygen delivery (HDO2). The increase in HDO2 was not associated with an improvement of hepatic oxygen supply-uptake ratio, since hepatic oxygen uptake (HVO2) also increased. After hepatectomy, the increases in portal venous blood flow and HDO2 were not accompanied by an increase in HVO2. The stimulation of hepatocellular oxygen metabolism by dobutamine and depressed responsiveness of adrenoceptors on hepatocytes in which metabolism was already augmented are the likely explanation for the different reactions before and after hepatectomy.

Adult↗
PubMed1992

Spectral analysis of heart rate variability during isoflurane anesthesia.

The autonomic nervous system is an important neural control system for maintaining cardiovascular stability in humans. Analysis of heart rate variations may provide important clinical information on the influence of anesthesia on the autonomic nervous system and the central nervous system. Therefore, the effects of 1.0, 1.5, and 2.0 minimum alveolar concentrations of isoflurane anesthesia on beat-to-beat heart rate variations were studied in ten patients (ASA Physical Status 1). Spectral analysis was used to determine the intensity of the variations. For each power spectrum, the frequency components were identified as follows: 1) the parasympathetically mediated respiratory component (0.15-0.4 Hz) and 2) both parasympathetically and sympathetically mediated components (0.04-0.15 Hz). The latter was subdivided into the low-frequency component (0.04-0.09 Hz) of vasomotor origin and the mid-frequency component (0.09-0.15 Hz) of baroreceptor origin. Marked reductions in the power of heart rate variations, at all frequencies, were found during isoflurane anesthesia, indicating isoflurane decreased total autonomic nervous system activity. Isoflurane decreased the high-frequency and mid-frequency components in a concentration-dependent manner. The low-frequency component increased transiently at 1.5 minimum alveolar concentrations concomitant with the burst suppression in the electroencephalogram. The ratio of mid-frequency to high-frequency components did not change significantly during isoflurane anesthesia compared with the awake period. These frequency characteristics of heart rate variations during isoflurane anesthesia suggest there are dose-related decreases in autonomic nervous system activity in both the vagus and the cardiac sympathetic nerves.

Adult↗
PubMed1992

Effects of probucol on impaired cardiac performance and lipid metabolism in streptozotocin-induced diabetic rats.

Plasma lipids and cardiac performance were studied in diabetic rats treated with probucol. Male Wistar rats were rendered diabetic with a single intraperitoneal injection of streptozotocin (STZ, 75 mg/kg). Nondiabetic control rats received the vehicle alone. Two weeks after STZ or vehicle injection, control and diabetic rats were randomly assigned to probucol-treated or untreated groups. The rats in the two probucol-treated groups (control- and diabetic-probucol groups) were fed a diet containing 1% probucol (w/w) for 4 weeks. Blood was drawn, and then cardiac performance was assessed by the isolated perfused working heart technique. Probucol treatment had no effect on the cardiac performance of the nondiabetic control rats. The peak left ventricular developed pressure and maximum rate of change in left ventricular pressure during systole were significantly greater in the probucol-treated diabetic rats than in the untreated diabetic rats (p less than 0.05), although cardiac performance did not improve to the level in the nondiabetic rats. Plasma cholesterol, free fatty acid, and phospholipid were significantly elevated in the untreated diabetic rats, and probucol treatment decreased significantly the plasma cholesterol and free fatty acid concentrations (p less than 0.05). These data suggest that probucol treatment improves plasma lipids and cardiac performance in rats with experimental diabetes and may prevent diabetic cardiomyopathy.

Animals↗
PubMed1992

A case report of Moyamoya disease: successfully treated with Chinese medicine.

The incidence of Willis' ring obstruction (Moyamoya disease) in Japan is higher than in Europe and North America. The therapeutic technique usually employed is either surgery or Western drug treatment. But these methods are still not satisfactory. We attempted to apply Chinese medicinal treatment to a patient with Moyamoya disease. This patient was referred to our department because of the ineffectiveness of Western drug treatment. The patient made satisfactory progress with Gui-Zhi-Fu-Ling-Wan and Xiao-Xu-Ming-Tang. We also noticed the improvement of the "stagnated blood condition." Whole blood viscosity was decreased and the blood flow rate in the bulbar conjunctiva was increased.

Blood Viscosity↗
PubMed1992

Inhibition of mouse alveolar macrophage production of tumor necrosis factor alpha by acute in vivo and in vitro exposure to tobacco smoke.

We investigated the effects of tobacco smoke exposure on the production of tumor necrosis factor alpha (TNF alpha) by alveolar macrophages (AM) in mice (C57BL/6). The results obtained are as follows: (1) In vivo tobacco smoke exposure caused a significant decrease in the production of TNF alpha by AM with the stimulation of lipopolysaccharide (LPS; control group: 19.32 +/- 5.52 U/ml, smoked group: 4.28 +/- 0.98 U/ml; p less than 0.05). (2) In vitro exposure of AM to tobacco smoke extracts (water-soluble extracts) also caused a decrease in the production of TNF alpha up to 93% of control with stimulation of LPS (p less than 0.05) without any decrease in cellular viability. We concluded that the production of TNF alpha by AM was impaired by smoking via direct action of the factors present in tobacco smoke.

Animals↗
PubMed1992

Effect of sympathetic nerve stimulation on lung vascular permeability in the rat.

The present study was undertaken to evaluate the role of sympathetic nerves in increasing lung vascular permeability. An isolated rat sympathetic nerve-lung preparation was used. Three minutes after an increase in lung weight was induced by elevating the intravascular pressure, stimulation of sympathetic nerves was performed in the presence of papaverine, which further increased the lung weight in a graded manner. After the nerve stimulation, deposits of carbon were observed in alveolar macrophages and perivascular walls, indicating an increase in vascular permeability. The response of lung weight to the sympathetic nerve stimulation was altered, depending on the magnitude of intravascular pressure change as well as on the voltage and frequency of electrical stimulation. Furthermore, these responses were prevented by tetrodotoxin. Calculation of the relationship between the maximal slope of the graded lung weight gain and the slope obtained just before the nerve stimulation gave a slope ratio at a frequency of 30 cps in normal rats of 4.47 +/- 0.21. Treatment with phentolamine diminished the value to 1.93 +/- 0.15, and with reserpine, to 1.43 +/- 0.14. In reserpinized rats, the slope ratio was restored by an administration of norepinephrine to 2.11 +/- 0.05 at 30 cps, being further increased by propranolol and blocked partially by phentolamine. The capillary filtration coefficient was not affected by either of the agents. In capsaicin-treated rats, sympathetic nerve stimulation did not cause any response in terms of lung weight (slope ratio = 1.0).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Expression of a 66-kD heat shock protein associated with the process of cyst formation of a true slime mold, Physarum polycephalum.

Under unfavorable conditions for growth, haploid myxoamoebae of Physarum polycephalum retracted their pseudopodia and changed their cell shape into disk-like form, after which they constructed the cell walls to form microcysts. These morphological changes of haploid cells were associated with changes in intracellular distribution of actin filaments. Staining with phalloidin showed that actin filaments were almost uniformly distributed throughout the cytoplasm of the myxoamoebae. When these cells were transferred to a cyst-inducing medium, the actin structures changed into short rods or dots, after which the rods/dots disappeared in the microcysts. An incubation of the myxoamoebae in the cyst-inducing medium caused the synthesis of several proteins, among which a 66-kD protein was most prominently induced. The morphological changes and the induction of the 66-kD protein was pronounced at elevated temperatures, e.g. 40 degrees C. The 66-kD protein was not induced, however, when plasmodia of the same species were incubated at 40 degrees C. We found that the 66-kD protein was co-precipitated with polymerized actin and bound to ATP-agarose. A double staining of the disk-shaped cells with anti-66-kD protein antibody and phalloidin revealed superimposable localization of the 66-kD protein and actin filaments in the short rods or dots. Although the induction of the 66-kD protein was enhanced at high temperatures, the protein was immunologically unrelated to the common heat shock proteins, HSP70 and HSP90, those are highly conserved during evolution. These results indicate that the 66-kD protein is a novel heat shock protein which is specifically expressed during cyst formation.

Actins↗
PubMed1992

The substitution of cysteine 17 of recombinant human G-CSF with alanine greatly enhanced its stability.

Human recombinant granulocyte-colony stimulating factor (rhG-CSF) has one free cysteine at position 17 and has two disulfide bridges (Cys36-Cys42 and Cys64-Cys74). The Cys17 of rhG-CSF was substituted with Gly, Ala, Ser, Ile, Tyr, Arg, and Pro, or deleted using site-directed mutagenesis in order to improve its thermostability. With the exception of Pro17-rhG-CSF, all mutant proteins retained biological activity which promotes the growth of mouse bone marrow cells in vitro. Among these mutant proteins, Ala17-rhG-CSF had more than 5 times higher stability than rhG-CSF. But Ser17-rhG-CSF had almost same stability as rhG-CSF and other mutant proteins had only lower stability.

Alanine↗
PubMed1992

Lysinuric protein intolerance presenting deficiency of argininosuccinate synthetase.

A 35-yr-old woman, who suffered from relapsing coma with hyperammonemia for 17 yr, was diagnosed to have lysinuric protein intolerance (LPI). Increased urinary dibasic amino acids (lysine, arginine and ornithine) and impaired absorption of orally administered lysine and arginine proved the defects of renal tubular and intestinal transport of dibasic amino acids. These defects are the primary cause of impaired urea cycle metabolism in LPI. Further, the level of argininosuccinate synthetase (ASS), a urea cycle enzyme, was analyzed and it was found to be below the normal level. This is the second reported case of LPI presenting ASS deficiency.

Adult↗