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Biomedical subjects

Y Ohta

Publications and source records attributed to Y Ohta.

At least 397 records · Page 22Linked to original sources
PubMed1996

Tracheal, circulatory, and respiratory responses to femoral nerve stimulation.

Tracheal, circulatory, and respiratory responses to electrical stimulation of the afferent nerve from the hindlimb were analyzed in decerebrate, paralyzed, and mechanically ventilated dogs. Tension of the tracheal smooth muscle (TSM), arterial blood pressure, and phrenic nerve activity (PNA) were measured during stimulation of the proximal end of the transected femoral nerve (FNS) with train pulses (duration; 0.5 ms, frequency; 40 Hz). With low intensity (e.g., 0.62 V) FNS, TSM exhibited relaxation, arterial pressure decreased, and neural respiratory output (NRO) was reduced (3 of 8 dogs) or unchanged (5 of 8 dogs). With increases in stimulus intensity, TSM always exhibited relaxation while arterial pressure and NRO exhibited excitatory responses almost at the same thresholds (approximately 5 V). The TSM relaxation and the excitatory NRO and arterial responses augmented with increases in stimulus intensity up to 16 times of threshold of the excitatory NRO response. TSM response was blocked by intravenous atropine but pressor response and phrenic response were not. The arterial response disappeared after administration of a ganglionic blocker. These findings suggest that TSM, arterial pressure, and PNA may be controlled by one neuronal mechanism during high intensity FNS, but that arterial pressure and PNA may be modified by another mechanism in an inhibitory direction when the stimulus intensity is low. This study suggested the existence of a neural mechanism which controls the airway and cardiorespiratory systems properly to execute exercise. Physiological significance of the responses to low intensity femoral nerve stimulation was uncertain.

Animals↗
PubMed1996

Lack of immunoreactivity for myoglobin in skeletal muscle of acute stroke patients.

Sternothyroid muscle biopsy specimens, obtained during tracheostomies from 15 patients with acute stroke and respiratory failure, were examined immunohistochemically to immunoreactivity to myoglobin (Mb). A marked decrease or lack of Mb immunoreactivity in association with hyaline degeneration was observed in 0.8 to 44.4% of the muscle fibers on both the paretic and non-paretic sides of all patients. The percentages of negative staining for Mb were less than 3.1% in 5 patients with acute respiratory failure due to causes other than stroke. The pattern and incidence of attenuated Mb immunoreactivity in the muscle fibers was found to be distinctively different in the two patients groups. In one group of 5 patients, a large number of muscle fibers (24.8 +/- 15.6%) had no Mb staining and were clearly bordered and grouped. In another 10-patient group, only a limited number of muscle fibers (3.3 +/- 2.5%) had no staining for Mb and these fibers were scattered. Four patients in the former group had catastrophic outcomes, while all the patients in the latter group survived. Ischemia, produced by an increase in catecholamines, and the consequent vasoconstriction, rather than hypoxemia seemed to be the cause of the negative immunoreactivity for Mb in the group pattern. In contrast, hypoxemia may have caused the scattered pattern of negative Mb immunoreactivity. It was concluded that negative immunostaining for Mb in muscle fibers represents a common and characteristic complication in acute stroke patients.

Acute Disease↗
PubMed1996

Involvement of oxidative stress in D-xylose-induced cataractogenesis in cultured rat lenses.

In order to clarify the involvement of oxidative stress in in vitro sugar-induced cataractogenesis, we examined changes in lipid peroxide, reduced glutathione, vitamin E, and water contents following cataractogenesis in rat lenses cultured with 20 mM D-xylose over a period of 24 h. In D-xylose-treated lenses, an apparent opacity appeared at the equator after 6 h of D-xylose treatment, increases in lipid peroxide and water contents and decreases in reduced glutathione and vitamin E contents occurred with the appearance of opacity. We further examined the effect of the treatment of vitamin E in a liposomal form on cataractogenesis and the changes of lipid peroxide, reduced glutathione, vitamin E, water, and xylitol contents in rat lenses cultured with 20 mM D-xylose for 24 h. This vitamin E treatment significantly prevented not only cataractogenesis, but also an increase in lipid peroxide content and a decrease in vitamin E content in the D-xylose-treated lenses. However, the vitamin E treatment had no effect not only on a decrease in reduced glutathione content, but also on increases in water and xylitol contents, which are known to be induced via aldose reductase, in the D-xylose-treated lenses. These results indicate that not only osmotic stress but also oxidative stress should be involved in cataractogenesis in rat lenses cultured with D-xylose and support the involvement of oxidative stress in in vitro sugar-induced cataractogenesis.

Animals↗
PubMed1996

Eye movement modifies motion trajectory of a moving target.

Smooth pursuit eye movements have strong modulating effects on perceived motion both temporally and spatially. Abrupt changes in the direction of a target cause non-veridical perceived velocity and trajectory pattern when a visual cues appear with the moving target. In addition, this condition of non-veridical velocity and trajectory perception increases no visual cues are presented. Non-veridical perception was also connected with target velocity: the more difficult the eye pursuit, the more frequent was the non-veridical perception.

Acceleration↗
PubMed1996

[A clinical analysis of the patients with chest wall reconstruction].

Twenty-three patients underwent chest wall reconstruction in our department. The underlying disease was bronchial carcinoma in 14, urachus tumor in 2, breast cancer in 1, renal cancer in 1, thymic Hodgkin's lymphoma in 1, tuberculosis in 1, fibrosarcoma in 1, and pseudoaneurysm of the aortic arch caused by reconstructed material in 1. An average of 3.4 ribs were resected in 18 patients and sternectomies were performed in 5. Chest wall reconstruction was performed with Marlex mesh in 14, Marlex mesh with methyl methacrylate in 5, Marlex mesh with steel wire in 1, Marlex mesh with omentopexy in 1, Marlex mesh with A-O plate in 1, and net formation with catgut in 1. There was no operative death. Postoperative wound infection occurred in only 1 patient with Marlex mesh cleaned by irrigation and administration of antibiotics. Three patients with Marlex mesh and metyl methacrylate required removal of the prosthetic material postoperatively because of wound infection in 1, seroma in 1, and dislocation of the former reconstructed material in 1. One patient with Marlex mesh and steel wire had protrusion of the wire under the skin and the wire was removed. Eleven patients of lung cancer died at 2-17 months after surgery. In conclusion, chest wall reconstruction with Marlex mesh had excellent results, and chest wall resection and reconstruction for malignancy could be good palliation.

Adult↗
PubMed1996

Discordant phenotype in siblings with X-linked agammaglobulinemia.

X-linked agammaglobulinemia (XLA) is a congenital humoral immunodeficiency caused by a defect in a B-cell-specific signaling molecule, Btk. There has been little concordance of phenotype with genotype in this disorder, and defects in Btk cause immunodeficiencies that range from mild impairment to complete inability to produce antibodies. The factors modifying the phenotype of XLA are not understood. The current study is the first description of two male siblings with identical T134 --> C mutations in the translation initiation ATG of Btk who have different clinical phenotypes. The proband lacks immunoglobulins and B cells and has recurrent infections, while the elder, affected brother has normal levels of IgG and IgM and very few infections. Both have undetectable levels of Btk kinase activity in circulating mononuclear cells. Complete sequencing of Btk gene transcripts in both brothers revealed no additional mutations to account for the discordant phenotypes. This description provides unequivocal evidence that the phenotype of XLA is influenced by factors additional to the Btk gene.

Adolescent↗
PubMed1996

Focal accumulation of iodine-123-BMIPP in liposarcoma of the thigh.

Findings for focal accumulation of 123I-15-(p-iodophenyl)-3-R,S-methylpentadecanoic acid ([123I]BMIPP) in a patient with liposarcoma of the thigh are presented. Iodine-123-BMIPP accumulated heterogeneously in the liposarcoma. The region with marked accumulation of [123I]BMIPP was diagnosed as mixoid liposarcoma. The region with little accumulation of [123I]BMIPP was diagnosed as well-differentiated liposarcoma. Differences in the accumulation of [123I]BMIPP may reflect differences in fatty acid metabolism between histopathological types of liposarcoma.

Adult↗
PubMed1996

[Study on a predictive marker for evaluating the effectiveness of steroid therapy in IgA nephropathy-significance of extracapillary changes].

In order to obtain a useful index that can predict the effectiveness of steroid therapy in IgA nephropathy, we investigated the relationship between steroid therapy and extracapillary change. We analysed 51 cases consisting of a group of 24 cases in which steroid was administered (initial dose: prednisolone 20-60 mg/day orally, or pulse therapy), and a group of 27 cases in which steroid was not administered. First of all, we compared these two groups in terms of a clinical improvement rate over 3, 12 and 60-month-periods after the therapy, respectively. It was found that steroid therapy led to a higher improvement rate (p < 0.01-0.05), indicating that steroid is effective for IgA nephropathy. Among the group undergoing steroid therapy, the frequency of cellular crescents (C) was significantly higher (p < 0.05-0.01) in the cases in whom steroid was effective and that of fibrous crescents or adhesion (F) was significantly lower (p < 0.05-0.01). We then assessed C/F in each case of the steroid-administered group, and studied its relationship with the improvement rate. As a result, the improvement rate was below 50% in the group of C/F < 0.25, over 50% of the group of 0.25 < or = C/F < 0.75, and 100% of the group of 0.75 < or = C/F. Accordingly, we concluded that C/F could be used a parameter for predicting the effectiveness of steroid therapy in IgA nephropathy and for determining indications for steroid therapy.

Adolescent↗
PubMed1996

[Effects of halothane, isoflurane, enflurane, and sevoflurane on the monosynaptic reflex response in the isolated spinal cord of newborn rats].

Monosynaptic reflex responses (MSRs) in the isolated spinal cord of newborn rats were elicited in the ventral root by stimulation of the ipsilateral dorsal root. MSRs were considered to be mediated by non-NMDA class glutamate receptors. We studied the depressant effects of halothane, isoflurane, enflurane, and sevoflurane on MSR amplitudes as a function of anesthetic concentration comparing with MAC value of each anesthetics. The spinal cord of newborn rats were rapidly dissected out, and placed in a chamber superfused with artificial cerebrospinal fluid (ACSF, pH 7.4, 34 degrees C) equilibrated with 95% O2 - 5% CO2. Anesthetic gases were delivered with specific vaporizers and bubbled in the ACSF. Each anesthetic concentration was determined by gas chromatography. Either of the anesthetics reversibly depressed MSR amplitudes in a concentration dependent fashion. Concentration-response curves for MSR amplitudes were constructed and the concentrations which produced a half-maximum inhibition (IC50) were 0.56, 0.65, 0.97 and 1.18 mM for halothane, isoflurane, enflurane, and sevoflurane, respectively. These IC50 values correlated well with those of MAC values (r = 0.999, P < 0.001) obtained from adult rats in an in vivo condition. The MSR response in the isolated spinal cord of newborn rats is considered as a useful model for analysis of potency of volatile anesthetics.

Anesthetics, Inhalation↗
PubMed1996

[Evaluation of differential media in Helicobacter pylori culture].

Culture is one of the important methods for detecting Helicobacter pylori(Hp). Culture method is generally lower sensitive in comparison with other Hp detection methods. However, culture is necessary for determination of MIC and analysis of bacteriological characteristics. Several culture media are now commercially available for Hp. In this study, we compared commercial media with our original medium. Original medium for Hp culture was most sensitive and showed no false-positive results compared with other commercial media.

Culture Media↗
PubMed1996

[Suppression by methylprednisolone of the expression of LFA-1 by alveolar macrophages in irradiated rat lungs].

A common side effect of radiotherapy is the development of fibrosis in the irradiated tissue. To study the effects of methylprednisolone on acute radiation-induced lung injury, we counted neutrophils, lymphocytes, and macrophages, and measured the expression on alveolar macrophages of lymphocyte function associated molecule-1 (LFA-1) in bronchoalveolar lavage fluid recovered from irradiated rat lungs. Twenty 10-week-old male Wistar rats were divided into 4 groups of 5 rats each: (1) a radiation group (R), which received 20 Gy of radiation from 60Co to the left hemithorax in one fraction; (/) a methylprednisolone treatment group (RS), which received the same dose of radiation as the R group, along with 2.0 mg x kg-1 of methylprednisolone (6 alpha methylprednisolone 21-acetate) by intramuscular injection 6 hours before and every 48 hours after irradiation; (3) an untreated control group (C); and (4) a methylprednisolone control group (S), which received the same dosage of methylprednisolone as the RS group. Rats were kept under specific-pathogen-free conditions. Bronchoalveolar lavage of the left lung was done in all 4 groups 2 week after irradiation. The number of neutrophils in the recovered fluid was significantly higher in the R and RS groups than in the C and S groups. The expression of LFA-1 on alveolar macrophages was significantly higher in the R group than in the RS, C, and S groups. The number of neutrophils in bronchoalveolar lavage fluid and the expression of LFA-1 on alveolar macrophages were significantly higher in the R group than in the RS groups. These results suggest that the increase in the expression of LFA-1 on alveolar macrophages and the increase in the number of neutrophils in bronchoalveolar lavage fluid are related to acute radiation-induced lung injury. Methylprednisolone suppressed the expression of LFA-1 on alveolar macrophages and the increase in the number of neutrophils measured in bronchoalveolar lavage fluid 2 weeks after irradiation.

Animals↗
PubMed1996

Effects of sphingomyelinase and sphingosine on arterial vasomotor regulation.

The sphingomyelin pathway is an important signal transduction system regulating various cellular functions. However, little is known about the effect of sphingomyelin metabolites on vasomotor function. We examined the vascular effects of sphingomyelin, sphingosine, and sphingomyelinase (SPMase) in vitro. In pig coronary rings precontracted with prostaglandin F2 alpha, sphingosine and SPMase evoked initial contraction and subsequent gradual relaxation; however, sphingomyelin did not influence the tone. The initial contractions in response to either SPMase (40 microU/ml to 0.4 U/ml) or sphingosine (0.5-10 microM) treatment were abolished in rings denuded of endothelium. This initial contraction in response to sphingosine treatment was significantly attenuated by a cyclo-oxygenase inhibitor indomethacin, but not altered by either a nitric oxide synthase inhibitor, N omega-monomethyl-L-arginine (L-NMMA), a protein kinase C (PKC) inhibitor staurosporine, or superoxide dismutase (SOD, 100 U/ml). Incubation of coronary rings with sphingosine (10 microM) or SPMase (0.4 U/ml) for 120 min significantly attenuated subsequent endothelium-dependent relaxation in response to thrombin and A23187, but did not affect endothelium-independent relaxation in response to sodium nitroprusside. In contrast, sphingomyelin (10 microM) did not alter the endothelium-dependent relaxation. In conclusion, in the sphingomyelin pathway, sphingosine induces vasoconstriction in coronary arteries that seems to be mediated by the release of cyclooxygenase-sensitive vasoconstrictor prostanoids from the endothelium. Sphingosine also induced endothelial dysfunction characterized by impaired endothelium-dependent relaxation. Thus, the sphingomyelin pathway may be an important regulator of vascular function.

Animals↗
PubMed1996

[Hemodynamic changes during laparoscopic cholecystectomy under different anesthesia methods].

We measured cardiovascular changes associated with insufflation of carbon dioxide and the reverse Trendelenburg position during laparoscopic cholecystectomy. Twenty eight ASA I and II patients were assigned to three groups depending on the anesthesia method. Inhalation anesthesia (I) group (n = 10) was maintained with nitrous oxide-oxygen-isoflurane (GOI), fentanyl (F) group (n = 10) was maintained with GOI and fentanyl (4.8 +/- 0.9 micrograms . kg-1), and epidural (E) group (n = 8) was maintained with GOI and continuous epidural infusion (1.5% lidocaine, 5 ml . h-1). Swan-Gantz catheters were inserted to the patients in groups F and E. Heart rate and arterial blood pressure increased significantly in group I and this elevated pressure was difficult to control using even high concentrations in isoflurane. Heart rate, arterial blood pressure, right atrial pressure, pulmonary arterial pressure cardiac output, and systemic and pulmonary vascular resistance were not significantly changed in groups E and E. Stroke volume decreased significantly in group F after pneumoperitoneum. Our result showed that hemodynamics during laparoscopic cholecystectomy were the most stable in group E.

Adult↗
PubMed1996

[Acid base changes and muscle relaxants].

Previous publications have provided conflicting results concerning the effects of respiratory and metabolic acid base changes on the neuromuscular effects of nondepolarizing muscle relaxants. The varying results can be attributed not only to experimental design or species difference, but also to the accompanying changes in the pharmacokinetics in vivo. Using the phrenic nerve-hemidiaphragm preparation of rats, in which many variables of in vivo studies can be eliminated, respiratory and metabolic acid-base changes were induced by varying carbon dioxide (PCO2) and bicarbonate (HCO3) concentrations in the Krebs' solution and their effects on the potencies of muscle relaxants were compared. Decreasing pH by increasing Pco2 or by decreasing HCO3 increased the potencies of the monoquaternary relaxants (d-tubocurarine, vecuronium and rocuronium), while pH changes did not affect the potencies of the bisquaternary relaxants (metocurine, pancuronium and pipecuronium). Above difference between mono- and bisquaternary relaxants may reflect pH-induced changes in the ionization of the tertiary ammonium and resulting in changes in the sensitivity to the anionic nicotinic receptors. Neostigmine-induced antagonism was not affected by acid-base changes. These results in vitro were compared and correlated with the previous results in vivo.

Acid-Base Equilibrium↗
PubMed1996

Response of endogenous reduced glutathione through hepatic glutathione redox cycle to enhancement of hepatic lipid peroxidation with the development of acute liver injury in mice intoxicated with carbon tetrachloride.

In the liver of male ddY mice intoxicated once with carbon tetrachloride (CCl4), the change in lipid peroxide (LPO) level with the development of damage over a 24 hr period after i.p. treatment of the toxicant (1.0 mL/kg) was compared with the changes in reduced glutathione (GSH) and oxidized glutathione (GSSG) levels, GSSG/GSH ratio, and activities of the glutathione redox cycle-related enzymes such as Se-dependent glutathione peroxidase (Se-GSH-px), glutathione reductase (GSSG reductase), and glucose-6-phosphate dehydrogenase (G-6-PDH) and of Se-independent glutathione peroxidase (non-Se-GSH-px) with the development of damage during the same period. An apparent liver injury was observed 0.5 hr after CCl4 treatment and the injury progressed rapidly later than 8 hr, judging from the activities of serum transaminases, marker enzymes of liver cell damage. Hepatic LPO level slightly increased once during the first 4 hr after CCl4 treatment and a marked increase in the level occurred later than 12 h, while serum LPO level increased later than 12 h. Hepatic GSH level decreased rapidly during the first 4 hr after CCl4 treatment and the decreased level recovered slowly thereafter, although the recovered level did not reach the control level. Hepatic GSSG level rapidly increased once during the first 1 hr after CCl4 treatment and an increase in the level occurred again later than 12 h. Hepatic GSSG/GSH increased during the first 1 hr and later than 8 hr after CCl4 treatment, although the ratio was maintained above the control level later than 0.5 h. Hepatic Se-GSH-px activity increased during the first 2 hr after CCl4 treatment and later than 8 h, while hepatic non-Se-GSH-px activity increased during the first 1 hr but decreased below the control level at 8 and 12 h. Hepatic GSSG reductase activity decreased during the first 2 hr after CCl4 treatment but the decrease activity returned up to the control level at 8 h. Hepatic G-6-PDH activity increased rapidly during the first 2 hr after CCl4 treatment and the increase proceeded slowly thereafter. These results indicate that although hepatic lipid peroxidation is enhanced at early and progressed stages of liver injury in mice intoxicated once with CCl4, endogenous GSH through hepatic glutathione redox cycle can respond well to enhanced hepatic lipid peroxidation at an early stage of liver injury but not enough to enhanced hepatic lipid peroxidation at a progressed stage of liver injury.

Alanine Transaminase↗
PubMed1996

[The spread of contrast medium in the epidural space and the analgesic area in epidural anesthesia in elderly patients].

We evaluated the relationship between the spread of contrast medium in epidural space and the analgesia area in epidural anesthesia in elderly patients. The spread of contrast medium was examined radiographically after the injection of iotrolan 5 ml through the epidural catheter and the analgesia area was examined by pin prick following the epidural injection of the same volume of 1% lidocaine. In lumbar group (group L) (n = 10), the radiographic spread was 10.4 (4-17) segments (mean, minimum-maximum) and the analgesic area was 8.5 (4-15) dermatomes. In cervical or thoracic group (group C/T) (n = 10), the radiographic spread was 12.4 (8-17) segments and the analgesic area was 10.4 (6-15) dermatomes. The dose of local anesthetics required to get analgesia per. one dermatome was 0.7 (0.3-1.3) ml in group L and 0.5 (0.3-0.8) ml in group C/T. The spread of contrast medium correlated well with the analgesic area in both groups (group L:Y = 0.79X + 0.31, r = 0.92, group C/ T:Y = 0.80X + 0.52, r = 0.79). The mean dose of local anesthetics required for analgesia was smaller than that of previous reports although individual variations were large. We conclude that the spread of contrast medium is useful for predicting the spread of epidural block.

Aged↗