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Biomedical subjects

Y Ishiguro

Publications and source records attributed to Y Ishiguro.

At least 37 records · Page 2Linked to original sources

Effect of xenon on autonomic cardiovascular control--comparison with isoflurane and nitrous oxide.

STUDY OBJECTIVES: To clarify the effect of xenon on the autonomic nervous system by comparing similar effects of isoflurane and nitrous oxide. DESIGN: Prospective, randomized study. SETTING: Operating room at a university hospital. PATIENTS: 39 ASA physical status I and II patients scheduled for general anesthesia. INTERVENTIONS: Patients were randomly allocated into one of three groups and received one of the following inhalational anesthetics: 56% of xenon (Group X), 0.94% of isoflurane (Group I), or 70% of nitrous oxide and 0.15% of isoflurane (Group N). Phenylephrine (pressor test) and nicardipine (depressor test) were given to assess baroreflex sensitivity. MEASUREMENTS AND MAIN RESULTS: Continuous blood pressure (BP) and electrocardiogram (ECG) were recorded before and during anesthesia to analyze heart rate (HR) variability and baroreflex sensitivity. Power spectrum of HR variability was calculated by fast Fourier transformation and power spectrum densities at low frequency (LF: 0.04-0.15Hz) and high frequency (HF: 0.15-0.40 Hz) were compared. Baroreflex sensitivity was calculated from the slope of regression for BP changes versus associated changes in R-R intervals. For HR variability, Group X showed lower power spectrum densities (ms(2).Hz(-1)) in LF and HF than did Group I (LF: 0.09 +/- 0.06 vs. 0.35 +/- 0.53; p < 0.05; HF: 0.40 +/- 0.34 vs. 0.98 +/- 0.68, p < 0.01). Group X had the lowest baroreflex sensitivity (ms.mmHg(-1)) via pressor test of the three study groups (Group X: 2.00 +/- 0.87, Group I: 3.53 +/- 2.14, Group N: 3.78 +/- 2. 17, p < 0.05). CONCLUSIONS: Xenon depressed both sympathetic and parasympathetic transmission more than isoflurane at 0.8 MAC. Xenon was also suggested to be relatively vagotonic.

Adolescent↗

Effect of xenon on endotracheal tube cuff.

STUDY DESIGN: To investigate the effect of xenon on the endotracheal tube cuff in comparison to that of nitrous oxide. DESIGN: Prospective, randomized study. SETTING: Laboratory in vitro testing of endotracheal tubes. INTERVENTIONS: Exposure of air-filled endotracheal tube cuffs to xenon or nitrous oxide (79 vol%) mixed with a balance of oxygen (21 vol%) for 3 hours. MEASUREMENTS: The intra-cuff pressure and gas volume in the cuff were measured for 3 hours. MAIN RESULTS AND CONCLUSION: Increase in pressure and gas volume was significantly less and slower with xenon than with nitrous oxide. More nitrous oxide passes into the cuff than xenon.

Air Pressure↗

MRI findings in patients with symptomatic localization-related epilepsies beginning in infancy and early childhood.

We studied MRI findings in patients with symptomatic localization-related epilepsy (S-LRE) beginning in infancy and early childhood and their relation to some clinical features. MRI findings were investigated in 183 patients with S-LRE beginning before 6 years of age. S-LRE was defined as an epileptic syndrome manifesting with only partial seizures at least for a certain period during the clinical course, having specific neuroimaging abnormalities considered to be related to epileptic seizures, moderate or severe mental retardation, or cerebral palsy. The timing of injury was divided into the following four groups; prenatal, perinatal, postnatal and unknown. It was presumed prenatal in 56 patients (31%), perinatal in 25 (14%), postnatal in 32 (18%) and unknown in 70 (38%). The median age at the onset of partial seizures was 24 months in the congenital (prenatal and unknown) group, 39 months in the perinatal group and 25 months in the postnatal group. The onset of partial seizures was later in the perinatal group than in the congenital group. There were no significant differences in the other clinical characteristics among groups except for more frequent association of cerebral palsy in the perinatal group than in the congenital group. Our study suggests that congenital (prenatal and unknown group) disorders may be most common in patients with S-LRE beginning in infancy and early childhood. The onset of partial seizures occurred later in the perinatal group.

Brain↗

Bispectral analysis of the electroencephalogram does not predict responsiveness to verbal command in patients emerging from xenon anaesthesia.

The bispectral index (BIS) is derived empirically from the electroencephalogram database of patients receiving common anaesthetics, but it may not be valid for uncommon agents. Therefore, we investigated how xenon affects the BIS. Nine and 11 patients were anaesthetized with 0.8 of the minimal alveolar concentration (MAC) of isoflurane (0.92%) and xenon (56%), respectively. After the end of operation, these concentrations were decreased in decrements of 0.1 MAC (isoflurane 0.12% or xenon 7%) and each new concentration was maintained for 15 min. This was repeated until the patient first opened her eyes or squeezed the investigator's hand on command. Isoflurane and xenon at 0.8 MAC reduced the BIS to a median of 40 (range 36-53) and 36 (30-61), respectively. With decreasing concentrations of isoflurane, the BIS increased progressively and it reached a median of 96 (90-98) when the patients awoke. In contrast, four patients receiving xenon responded to verbal command while the BIS was below 50 [median 45 (range 41-49)]. The remaining seven patients in the xenon group awoke when their BIS was greater than 80 [median 96 (range 82-98)], but in four of them the BIS was no greater than 50 when the xenon concentration was only 0.1 MAC (7%) higher than that associated with awakening. We conclude that low BIS values (< 50) do not guarantee adequate hypnosis during xenon anaesthesia.

Adult↗

Plasma concentration of fentanyl with xenon to block somatic and hemodynamic responses to surgical incision.

BACKGROUND: Although anesthesia with xenon has been supplemented with fentanyl, its requirement has not been established. This study was conducted to determine the plasma concentrations of fentanyl necessary to suppress somatic and hemodynamic responses to surgical incision in 50% patients in the presence of 0.7 minimum alveolar concentration (MAC) xenon. METHODS: Twenty-five patients were allocated randomly to predetermined fentanyl concentration between 0.5 and 4.0 ng/ml during 0.7 MAC xenon anesthesia. Fentanyl was administered using a pharmacokinetic model-driven computer-assisted continuous infusion device. At surgical incision each patient was monitored for somatic and hemodynamic responses. A somatic response was defined as any purposeful bodily movement. A positive hemodynamic response was defined as a more than 15% increase in heart rate or mean arterial pressure more than the preincision value. The concentrations of fentanyl to prevent somatic and hemodynamic responses in 50% of patients were calculated using logistic regression. RESULTS: The concentration of fentanyl to prevent a somatic response to skin incision in 50% of patients in the presence of 0.7 MAC xenon was 0.72 +/- 0.07 ng/ml and to prevent a hemodynamic response was 0.94 +/- 0.06 ng/ml. CONCLUSIONS: Comparing these results with previously published results in the presence of 70% nitrous oxide, the fentanyl requirement in xenon anesthesia is smaller than that in the equianesthetic nitrous oxide anesthesia.

Abdomen↗

Minimum alveolar concentration-awake of Xenon alone and in combination with isoflurane or sevoflurane.

BACKGROUND: The minimum alveolar concentration (MAC)-awake is a traditional index of hypnotic potency of an inhalational anesthetic. The MAC-awake of xenon, an inert gas with anesthetic properties (MAC = 71%), has not been determined. It is also unknown how xenon interacts with isoflurane or sevoflurane on the MAC-awake. METHODS: In the first part of the study, 90 female patients received xenon, nitrous oxide (N2O), isoflurane, or sevoflurane supplemented with epidural anesthesia (n = 36 for xenon and n = 18 per group for other anesthetics). In the second part, 72 additional patients received either xenon or N2O combined with the 0.5 times MAC-awake concentration of isoflurane or sevoflurane (0.2% and 0.3%, respectively, based on the results of the first part; n = 18 per group). During emergence, the concentration of an assigned anesthetic (xenon or N2O only in the second part) was decreased in 0. 1 MAC decrements every 15 min from 0.8 MAC or from 70% in the case of N2O until the patient followed the command to either open her eyes or to squeeze and release the investigator's hand. The concentration midway between the value permitting the first response to command and that just preventing it was defined as the MAC-awake. RESULTS: The MAC-awake were as follows: xenon, 32.6 +/- 6.1% (mean +/- SD) or 0.46 +/- 0.09 MAC; N2O, 63.3 +/- 7.1% (0.61 +/- 0.07 MAC); isoflurane, 0.40 +/- 0.07% (0.35 +/- 0.06 MAC); and sevoflurane, 0.59 +/- 0.10% (0.35 +/- 0.06 MAC). Addition of the 0.5 MAC-awake concentrations of isoflurane and sevoflurane reduced the MAC-awake of xenon to 0.50 +/- 0.15 and 0.51 +/- 0.16 times its MAC-awake as a sole agent, but that of N2O to the values significantly greater than 0.5 times its MAC-awake as a sole agent (0.68 +/- 0.12 and 0.66 +/- 0.14 times MAC-awake; P < 0.01, analysis of variance and Dunnett's test). CONCLUSIONS: The MAC-awake of xenon is 33% or 0.46 times its MAC. In terms of the MAC-fraction, this is smaller than that for N2O but greater than those for isoflurane and sevoflurane. Unlike N2O, xenon interacts additively with isoflurane and sevoflurane on MAC-awake.

Adult↗

Development of small hepatocellular carcinoma 80 months after clearance of hepatitis C virus with interferon therapy.

We describe a patient who had a complete and sustained response to interferon (IFN) therapy for chronic hepatitis C but developed small hepatocellular carcinoma (HCC) 80 months later. A 55-year-old Japanese man with hepatitis C virus (HCV) infection and histological features of chronic active hepatitis was treated with recombinant IFN alpha-2a, 9,000,000 U daily for 2 weeks followed by three times a week for 22 weeks. He successfully responded to IFN therapy with a normalization of serum alanine aminotransferase and continuous disappearance of serum HCV-RNA. However, 80 months after the cessation of IFN therapy, the patient's alpha-fetoprotein (AFP) level became elevated for the first time and HCC, 12 mm in diameter, was detected by routine ultrasonographic screening. Laparotomy revealed a small HCC with no metastasis, and the nontumorous liver demonstrated chronic inactive hepatitis. This case indicates the need for careful follow-up using ultrasonography and AFP testing for at least 7 years after completing IFN therapy in all patients with chronic hepatitis C, even if the patients have a complete response to the therapy.

Carcinoma, Hepatocellular↗

Prognostic impact of telomerase activity in patients with neuroblastoma.

Neuroblastoma is one of the most common malignant neoplasms occurring among children. The prognosis for this disease is strongly associated with age, disease stage, histology, and some biologic features. It has been reported that telomerase, a ribonucleoprotein enzyme, which maintains the telomere length in immortal cells, is related to disease stage and other biologic features. The purpose of this study was to evaluate the prognostic value of telomerase activity compared to TrkA expression in 65 patients with neuroblastoma. Telomerase activity and TrkA expression were examined in tissue samples collected between 1980 and 1994 from 65 patients by polymerase chain reaction-based telomerase activity. TrkA expression was examined by immunoblotting using a rabbit anti-gp140 proto-trk polyclonal antibody. Low telomerase activity was found in 22 of 30 (73.3%) patients with Stages 1, 2, or 4S neuroblastomas; 7 of 13 (53.8%) with Stage 3; and 8 of 22 (36.3%) with stage 4; no telomerase activity was detected in 7 of 22 (31.8%) patients with Stage 4 neuroblastoma. The 5-year event-free survival (EFS) rate was 86.5% for patients with low telomerase activity, while it was 53.8% for patients with high telomerase activity. By the combination of telomerase activity and TrkA expression, the 5-year EFS rate was highest among patients with a high TrkA expression and a low or non-existent telomerase activity (91.7%), and it was lowest among patients with a low TrkA expression and a high telomerase activity (29.6%). Thus, it appears that telomerase activity would be a useful prognostic factor for neuroblastoma, especially when used in combination with the TrkA expression.

Adolescent↗

Natural antibody against neuroblastoma among Japanese children with or without neuroblastoma.

BACKGROUND: This study was conducted to examine the distribution of a natural antibody against neuroblastoma (NB) among Japanese children as well as the clinical significance of the presence of this antibody in the sera during treatment in patients with International Neuroblastoma Staging System Stage 4 NB. METHODS: Human sera were obtained from 8 healthy volunteers, 82 patients with nonmalignant surgical diseases, and 35 patients with NB including 3 with Stage 1 disease, 6 with Stage 2, 7 with Stage 3, 17 with Stage 4, and 2 with Stage 4S. This natural antibody was quantified by flow cytometry and its antitumor activity was measured by complement-dependent cytotoxicity (CDC) using TGW cells, a human NB cell line, as the target. RESULTS: Immunoglobulin (Ig) M antibody and CDC activity against NB could be detected in all sera from healthy volunteers and from patients with nonmalignant surgical diseases who were age > 1 year. The amount of IgM antibody and CDC activity in sera from patients with Stage 4 NB at diagnosis consistently was low, most likely because of massive absorption by tumor cells. In this group of patients, the increased CDC activity detected during treatment was indicative of a favorable factor for survival (P < 0.005). CONCLUSIONS: A natural antibody against NB appears to exist in the sera of Japanese children. The sequential assessment of the levels of this antibody in the sera from Stage 4 NB patients during treatment may serve as a prognostic indicator.

Adolescent↗

Genetic analysis of the susceptibility in rats to aberrant crypt foci formation by 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine, PhIP.

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), the most abundant heterocyclic amine produced while cooking fish and meat, induces aberrant crypt foci (ACF) and colon cancers in rats. We previously reported that F344 rats were sensitive and ACI rats resistant to ACF formation by PhIP, and that the genetic susceptibility in F344 rats to ACF formation by PhIP was autosomally dominant over ACI rats. To identify candidate susceptibility genes in F344 rats, a preliminary genome-wide linkage analysis was employed using a subset of 170 progeny of (F344 x ACI)F1 x ACI backcross rats with either high or low sensitivity to ACF formation by PhIP. Three chromosomes, 1, 6 and 16, demonstrated the presence of loci with a logarithm of the odds (lod) scores of more than 1.0, and a susceptible gene for ACF formation by PhIP was suggested to reside on chromosomes 16.

Animals↗

Biological and biochemical properties of Ret with kinase domain mutations identified in multiple endocrine neoplasia type 2B and familial medullary thyroid carcinoma.

Several mutations were identified in the kinase domain of the RET proto-oncogene in patients with multiple endocrine neoplasia (MEN) 2B, familial medullary thyroid carcinoma (FMTC) or sporadic medullary thyroid carcinoma. We introduced seven mutations (glutamic acid 768-->aspartic acid (E768D), valine 804-->leucine (V804L), alanine 883-->phenylalanine (A883F), serine 891-->alanine (S891A), methionine 918-->threonine (M918T), alanine 919-->proline (A919P) and E768D/A919P) into the short and long isoforms of RET cDNA and transfected the mutant cDNAs into NIH3T3 cells. The transforming activity of the long isoform of Ret with each mutation was much higher that that of its short isoform. Based on the levels of the transforming activity, these mutant RET genes were classified into two groups; a group with high transforming activity (A883F, M918T and E768D/A919P) and a group with low transforming activity (E768D, V804L, S891A and A919P) (designated high group and low group). Interestingly, the level of transforming activity correlated with clinical phenotypes; high group Ret with the A883F or M918T mutation and low group Ret with the E768D, V804L or S891A mutation were associated with the development of MEN 2B and FMTC, respectively. In addition, we found that substitution of phenylalanine for tyrosine 905 present in the kinase domain abolished both transforming and autophosphorylation activities of low group Ret whereas it did not affect the activities of high group Ret.

Amino Acid Substitution↗

An accessory lobe of the liver disturbing closure of the umbilical ring.

The authors report a small omphalocele involving an accessory lobe of the liver (ALL) embedded in a cranial portion of the amniotic sac. The pedicle of liver tissue was markedly elongated. In this case, it was reasonable to assume that the ALL was formed during development of the embryonic body-wall folds and disturbed complete closure of the umbilical ring. Surgical resection of the ALL was performed to avoid its postoperative torsion. The pertinent literature is also reviewed.

Biopsy↗

Mucosal proinflammatory cytokine production correlates with endoscopic activity of ulcerative colitis.

Proinflammatory cytokines are believed to be involved in the pathogenesis of ulcerative colitis (UC). The aim of this study was to clarify the profiles of proinflammatory cytokine production in patients with UC in terms of disease intractability, endoscopic findings, and host response to lipopolysaccharide (LPS) stimulation. Colonic mucosal tissues were obtained from patients with active UC (n = 15, including 4 patients with intractable disease) and inactive UC (n = 7), non-inflammatory bowel disease (IBD) colitis (n = 11), and controls (n = 20). Organ culture was performed, and the amounts of four cytokines (described below) in the culture media were determined by enzyme-linked immunosorbent assay (ELISA). LPS stimulation enhanced interleukin (IL)-1beta, IL-8, and IL-6 production in colonic specimens from all groups, but enhanced tumor necrosis factor (TNF)-alpha production only in active UC specimens. Levels of IL-6, IL-8, and TNF-alpha were significantly higher in active UC than in non-IBD colitis, and the production of all three of these cytokines was correlated to the endoscopic grade of inflammation. The production of these cytokines was also significantly higher in patients with intractable disease receiving corticosteroids than in patients with non-intractable disease receiving corticosteroids. These results suggest that enhanced production of mucosal proinflammatory cytokines may be implicated in the pathogenesis of UC.

Adult↗

Role of microtubules in the contractile dysfunction of hypertrophied myocardium.

OBJECTIVES: We sought to determine whether the ameliorative effects of microtubule depolymerization on cellular contractile dysfunction in pressure overload cardiac hypertrophy apply at the tissue level. BACKGROUND: A selective and persistent increase in microtubule density causes decreased contractile function of cardiocytes from cats with hypertrophy produced by chronic right ventricular (RV) pressure overloading. Microtubule depolymerization by colchicine normalizes contractility in these isolated cardiocytes. However, whether these changes in cellular function might contribute to changes in function at the more highly integrated and complex cardiac tissue level was unknown. METHODS: Accordingly, RV papillary muscles were isolated from 25 cats with RV pressure overload hypertrophy induced by pulmonary artery banding (PAB) for 4 weeks and 25 control cats. Contractile state was measured using physiologically sequenced contractions before and 90 min after treatment with 10(-5) mol/liter colchicine. RESULTS: The PAB significantly increased RV systolic pressure and the RV weight/body weight ratio in PAB; it significantly decreased developed tension from 59+/-3 mN/mm2 in control to 25+/-4 mN/mm2 in PAB, shortening extent from 0.21+/-0.01 muscle lengths (ML) in control to 0.12+/-0.01 ML in PAB, and shortening rate from 1.12+/-0.07 ML/s in control to 0.55+/-0.03 ML/s in PAB. Indirect immunofluorescence confocal microscopy showed that PAB muscles had a selective increase in microtubule density and that colchicine caused complete microtubule depolymerization in both control and PAB papillary muscles. Microtubule depolymerization normalized myocardial contractility in papillary muscles of PAB cats but did not alter contractility in control muscles. CONCLUSIONS: Excess microtubule density, therefore, is equally important to both cellular and to myocardial contractile dysfunction caused by chronic, severe pressure-overload cardiac hypertrophy.

Animals↗

Preoperative pulse wave velocity fails to predict hemodynamic responses to anesthesia and to surgical stimulation.

STUDY OBJECTIVE: To determine whether pulse wave velocity (PWV), which is a useful indicator of cardiovascular disease, can predict the hemodynamic responses to anesthesia and surgical stimulation in surgical patients. DESIGN: Prospective, randomized study. SETTING: Operating rooms at a university hospital. PATIENTS: 30 ASA physical status I and II female patients presenting for elective gynecologic surgery. INTERVENTION: Patients who received one of the following anesthesia techniques were studied; isoflurane, sevoflurane and sevoflurane with nitrous oxide (N2O). MEASUREMENTS AND MAIN RESULTS: Patients underwent preoperative PWV measurements using an automatic PWV measurement device. Systolic blood pressure and heart rate levels were recorded at baseline, during anesthesia, and at skin incision. PWV had no significant correlation with percent changes of systolic blood pressure or heart rate, even after controlling the choice of anesthetic drugs. CONCLUSIONS: Preoperative PWV fails to predict hemodynamic responses to anesthesia and to surgical stimulation.

Adult↗

Xenon suppresses the hypnotic arousal in response to surgical stimulation.

STUDY OBJECTIVE: To evaluate the suppressive effects of xenon (Xe) on hypnotic arousal at skin incision. DESIGN: Prospective, randomized study. SETTING: Operating rooms at a university hospital. PATIENTS: 35 ASA physical status I and II patients presenting for elective lower abdominal surgery. INTERVENTIONS: Patients were randomly assigned to receive one of the following regimens: 1.3 minimum alveolar concentration (MAC) isoflurane, 1.3 MAC sevoflurane, 0.7 MAC Xe with 0.6 MAC sevoflurane, 1 MAC Xe with 0.3 MAC sevoflurane, or 0.7 MAC nitrous oxide (N2O) with 0.6 MAC sevoflurane (n = 7 each group). MEASUREMENTS AND MAIN RESULTS: The bispectral index (BIS) was measured at baseline, during anesthesia, and after skin incision. BIS increased significantly at skin incision from the values noted during anesthesia in the sevoflurane and N2O groups, whereas it remained stable at incision in the other three groups (mean change in BIS: 0 +/- 9 for isoflurane, 15 +/- 8 for sevoflurane, 5 +/- 6 for 0.7 MAC Xe, 4 +/- 11 for 1 MAC Xe, and 9 +/- 5 for N2O). CONCLUSIONS: Unlike N2O, Xe was able to suppress hypnotic arousal in response to surgical stimulation when administered with sevoflurane.

Abdomen↗