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Biomedical subjects

Y Nakata

Publications and source records attributed to Y Nakata.

At least 91 records · Page 5Linked to original sources
PubMed2000

Does an early increase in heart rate during tilting predict the results of passive tilt testing?

Head-up tilt testing is a useful but time-consuming procedure. If we could accurately predict the tilt testing results; we would be able to substantially shorten the duration of tilt protocol. To clarify the hypothesis that an early increase in heart rate (HR) during tilting can predict the passive tilt results in our protocol (80-degree angle for 30 minutes), we studied 115 consecutive patients (72 men, 43 women, mean age 46 +/- 19 years) who were clinically diagnosed with neurally mediated syncope. Twenty-nine (25%) patients had a positive tilt test (P group), whereas 86 (75%) patients had a negative test (N group). The early HR increase was defined as the maximum HR during the first 5 minutes of tilting minus the resting HR before tilting. The early HR increase was significantly higher in the P group (23.8 +/- 9.5 beats/min) than in the N group (17.5 +/- 8.2 beats/min, P = 0.0008), but it was negatively correlated with the tilt duration to positive response (r = -0.52, P = 0.0032) and the patient age in the entire study population (r = 0.62, P < 0.0001). Results of multiple regression analysis indicated that age, tilt result, and tilt duration were independently associated with the early HR increase. As a result, an early HR increase > or = 18 beats/min, the best apparent cut-off point obtained in our study, was a sensitive (100%) marker for prediction of a positive response at < or = 15 minutes of tilting, but it showed a low specificity (61%). In conclusion, an early HR increase during 80-degree tilting may be only predictive for a positive result < or = 15 minutes because it depends on the tilt duration to a positive response and patient age.

Adolescent↗
PubMed2000

Successful radiofrequency catheter ablation of left ventricular tachycardia following surgical correction of tetralogy of Fallot.

A 13-year-old boy had recurrent ventricular tachycardia following surgical correction of tetralogy of Fallot. Pharmacological management with multiple antiarrhythmic drugs failed, and the patient underwent electrophysiological evaluation. A reentrant tachycardia involving a slowly conducting region in the left ventricular outflow tract was demonstrated. We performed radiofrequency catheter ablation after identifying the essential components of the reentrant circuit. The ventricular tachycardia could no longer be induced and did not recur spontaneously during a 13-month follow-up.

Adolescent↗
PubMed2000

Circadian variation of vasovagal syncope.

INTRODUCTION: Circadian patterns have been demonstrated for several cardiovascular catastrophes. Chronobiologic factors play a role in the emergence of vasovagal syncope (VVS); however, diurnal variation of syncopal episodes in VVS has not been reported previously. METHODS AND RESULTS: We assessed daily distribution of the time of syncopal episodes in VVS. Time of syncope could be determined in 80 episodes in 54 patients (32 men and 22 women; mean age 37 years, range 12 to 67). Patients who were prescribed beta blockers or vasodilators, and who had syncopes related to alcohol intake, were excluded from the study. Head-up tilt testing was performed in 53 patients. The distribution of the episodes of VVS in 3-hour intervals differed significantly from uniform occurrence (P < 0.0001), with a peak frequency between 6 A.M. and noon (67.5% of total episodes). In patients who had experienced the initial syncope in the morning, most (78%) of the next syncopal episodes also occurred in the morning. There was no significant correlation between the time of last syncopes and tilt testing results. CONCLUSION: We demonstrated a prominent circadian variation in the frequency of VVS, with a peak in the morning. Recognition of the daily distribution of VVS is useful for patient education and therapeutic strategy.

Adolescent↗
PubMed2000

[Neural-immune interactions in dorsal root ganglia].

Interleukin-1 (IL-1) beta is a proinflammatory cytokine that is produced by a large variety of cells, including macrophages, fibroblasts, mesangial cells and endothelial cells, and is believed to play important roles in the inflammatory responses, including hyperalgesia. Hyperalgesia is characterized by intensified pain with a reduced threshold to somatic stimulation, and it is involved in chronic inflammatory disease. Substance P (SP), an undecapeptide, has been shown to relay noxious signals as a neurotransmitter in primary afferent neurons. Thus it is expected that the change of neuropeptide activities in primary afferent neurons is attributed to inflammatory hyperalgesia by IL-1 beta. In our recent studies, IL-1 beta was found to stimulate SP release from cultured dorsal root ganglion cells via the cyclooxygenase system. These studies provide a new insight in the neural-immune intercommunication involved in the pain-regulation system observed in inflammation-induced hyperalgesia.

Animals↗
PubMed2000

[Methodology of 80 degrees head-up tilt testing with and without low dose isoproterenol provocation in Japanese patients with neurally mediated syncope].

The usefulness of 80 degrees head-up tilt testing with and without low dose isoproterenol provocation was evaluated for the diagnosis of neurally mediated syncope (NMS) in Japanese. Head-up tilt testing was performed in 114 consecutive patients with clinical diagnoses of NMS (68 men, 46 women, mean age 46 +/- 21 years), and 57 times in 36 healthy volunteers (26 men, 10 women, mean age 31 +/- 8 years) who had no history of syncope or presyncope. Head-up tilt testing used an 80 degrees angle for 30 minutes (passive tilt), and if the passive tilt resulted in negative response, isoproterenol was infused at 0.01-0.02 microgram/kg/min and the tilt repeated for 10 minutes (isoproterenol tilt). A positive response was defined as the development of syncope or a presyncopal state associated with hypotension, bradycardia or cardiac arrest. The sensitivities of passive tilt testing for a positive response after 5-, 10-, 15-, 20-, 25- and 30-minute tilting were 1%, 9%, 14%, 19%, 24%, and 28%, respectively, and specificities after 5-, 10-, 15-, 20-, 25- and 30-minute tilting were 100%, 95%, 91%, 88%, 86%, and 84%, respectively. The sensitivities of isoproterenol tilt testing with 0.01 and 0.02 microgram/kg/min were increased to 37% and 48%, respectively. This improvement was statistically significant between the passive tilt and isoproterenol tilt testing with a dose of 0.02 microgram/kg/min (p < 0.01). However, specificities were comparable with those of the passive tilt testing (84% and 82%, respectively). In conclusion, 80 degrees passive tilt testing for 30 minutes showed a low sensitivity (28%) but acceptable specificity (84%). Low-dose isoproterenol provocation was useful for improving sensitivity (48%) while maintaining a comparable specificity (82%).

Adult↗
PubMed1999

Pertussis toxin-sensitive signal controls the trafficking of thymocytes across the corticomedullary junction in the thymus.

We investigated a role of chemokines in thymocyte trafficking. Genes encoding stromal cell-derived factor-1 and its receptor CXCR4 were detected in the cortex by in situ hybridization. Early immigrant cells did not express CXCR4, whereas their descendant CD44+CD25+CD4-CD8- cells did. CXCR4 expression was down-modulated when CD4+CD8+ double-positive cells became CD4+CD8- or CD4-CD8+ single-positive (SP) cells. Positively selected CD69+CD3intermediate cells gained CCR4, of which ligand, thymus activation-regulated chemokine, was expressed in the medulla. At the next developmental stage, CD69-CD3high cells lost CCR4 but gained CCR7. These results suggest that thymocytes use different chemokines along with their development. Blockade of chemokine receptor-mediated signaling by pertussis toxin perturbed the normal distribution of SP cells and resulted in the accumulation of SP cells in the cortex. Thus, a pertussis toxin-sensitive event controls the trafficking of SP cells across the corticomedullary junction.

Animals↗
PubMed1999

Successful simultaneous operation of concomitant early gastric cancer, transverse colon cancer, and a common iliac artery aneurysm.

In an 83-year-old Japanese man, concomitant bleeding colon cancer, early gastric cancer, and an expanding right common iliac artery aneurysm were evident. The patient underwent an artificial graft implantation, partial gastrectomy, and transverse colectomy, simultaneously. To protect against graft infection, the aneurysm was resected first, and then the retroperitoneum was tightly closed to isolate the graft from the peritoneal cavity. The postoperative course was uneventful, except for symptoms of temporary delirium. Recently, simultaneous surgery for concomitant abdominal aortic aneurysms and early gastric cancer has been commonly performed in Japan because the contamination of the peritoneal cavity during a gastrectomy is thought to be less severe than that during lower abdominal surgery. However, the positive rate for bacterial culture in colorectal resections is virtually the same as that in gastrectomies. Moreover, the incidence of graft infection is substantially lower than the positive rate for bacterial culture in surgery for aneurysms. Some surgeons object to a simultaneous resection due to fear of graft infection, but even the presence of infectious organisms does not always result in graft infection. The present case illustrates the benefits of a simultaneous operation for both an aneurysm and gastrointestinal malignancy.

Adenocarcinoma↗
PubMed1999

Acute myeloid leukemia with hypergranular cytoplasm accompanied by t(X;11)(q24;q23) and rearrangement of the MLL gene.

This report describes a unique case of acute myeloid leukemia with hypergranular cytoplasm and t(X;11)(q24;q23). The breakpoint on 11q23 was identified within the MLL gene. The hypergranular cytoplasm of leukemic cells and the associated coagulopathy resembled a characteristic of acute promyelocytic leukemia, despite the absence of RARalpha gene rearrangement in this case. The Xq24 site possibly played a role in this atypical blast phenotype.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1999

Evaluation of role of mast cells in the development of liver fibrosis using mast cell-deficient rats and mice.

BACKGROUND/AIMS: Several studies have suggested that mast cells participate in the development of liver fibrosis in rodent models. In this study mast cell-deficient mutant Ws/Ws rats and W/Wv mice were used to examine whether mast cells are involved in the development of liver fibrosis. METHODS: Liver fibrosis was induced in rats by bile duct resection (BDR), and by intraperitoneal injections of carbon tetrachloride (CCl4) or porcine serum, and in mice by intragastric administrations of CCl4, and BDR. The degree of fibrosis was evaluated by measuring the hydroxyproline content (microg/mg tissue) of the liver as an index of the collagen content. The density of mast cells (number/cm2 liver section) was determined by counting mast cells in liver sections stained with alcian blue. RESULTS: In the liver of control non-mutant (+/+) rats, mast cells were found principally in portal areas, and their average density was 200-300/cm2 liver section. BDR, and treatments with CCl4 and porcine serum increased the density of mast cells in the liver of +/+ rats several-fold, and induced liver fibrosis, increasing the liver hydroxyproline content markedly. BDR, and treatments with CCl4 and porcine serum also induced liver fibrosis in Ws/Ws rats, increasing the liver hydroxyproline content to a similar or higher level than that in +/+ rats. However, the average densities of mast cells in the liver of Ws/Ws rats after BDR and treatment with CCl4 and porcine serum were at most 10.2/cm2 liver section. The density of mast cells in the liver of control +/+ mice was extremely low (average, less than 2), and neither BDR nor treatment with CCl4 caused any significant increase in their density, whereas these treatments induced liver fibrosis and markedly increased the liver hydroxyproline content. Furthermore, treatment with CCl4 induced fibrosis in the liver of W/Wv mice similarly to that in +/+ mice, but the density of mast cells in the liver of W/Wv mice was very low (average, less than 1), and was not increased by treatment with CCl4. CONCLUSIONS: The present results indicate that mast cells play no role in the development of liver fibrosis in rats and mice.

Animals↗
PubMed1999

Binding affinity of sarpogrelate to 5-HT(2A) receptor ligand recognition sites in rat renal cortical and mesangial cells in culture.

We detected specific binding of 3H-ketanserin (0.6 nM) in rat renal cortical membrane preparations (4.70 +/- 0.57 fmol/mg protein) and mesangial cells (7.55 +/- 0.92 fmole/10(6) cells). Thus, the value in the renal cortical membrane corresponded to 15% of that in the cerebral cortical membranes (30.0 +/- 2.9 fmole/mg protein). The affinity of 3H-ketanserin binding displacement activities by sarpogrelate, a selective 5-HT2A receptor antagonist, in the renal cortical membrane (IC50; 0.448 +/- 0.061 microM) and mesangial cells (IC50; 0.656 +/- 0.187 microM) were almost 100-fold less than that in the cerebral cortical membrane (IC50; 4.62 +/- 1.02 nM). In the renal cortical membranes and mesangial cells, methysergide displaced a tiny fraction of 3H-ketanserin binding at concentrations up to 10 microM. These results did not explain the functional activity of 5-HT in the mesangial cells, and we conclude that specific 3H-ketanserin binding sites in the mesangial cells consisted of methysergide-resistant and non-serotonergic sites with low affinity for sarpogrelate.

DOM 2,5-Dimethoxy-4-Methylamphetamine↗
PubMed1999

Morbidity and mortality of hospitalized patients after the 1995 Hanshin-Awaji earthquake.

The objective of this study was to provide an overview of the morbidity and mortality of hospitalized patients during the Hanshin-Awaji earthquake. Medical records of 6,107 patients admitted to 95 hospitals (48 affected hospitals within the disaster area and 47 back-up hospitals in the surrounding area) during the initial 15 days after the earthquake were analyzed retrospectively. Patient census data, diagnoses, dispositions, and prognoses were considered. A total of 2,718 patients with earthquake-related injuries were admitted to the 95 hospitals included in our survey, including 372 patients with crush syndrome and 2,346 with other injuries. There were 3,389 patients admitted with illnesses. Seventy-five percent of the injured were hospitalized during the first 3 days. In contrast, the number of patients with illnesses continued to increase over the entire 15-day period after the earthquake. The mortality rates were 13.4% (50/372), 5.5% (128/2,346), and 10.3% (349/3,389) associated with crush syndrome, other injuries, and illness, respectively. The overall mortality rate was 8.6% (527/6,107 patients). Morbidity as well as mortality rates increased with age in patients with both injuries and illnesses. In the initial 15-day period, there was an unprecedented number of patients suffering from trauma, and they converged upon the affected hospitals. Subsequently an increased incidence of illness was observed. This survey underscores the need for adequate disaster response in such an urban situation.

Adolescent↗
PubMed1999

Insertion of the cuffed oropharyngeal airway (COPA) with propofol or sevoflurane in adults.

STUDY OBJECTIVES: To compare the respiratory depressant effects of propofol and sevoflurane used to facilitate the placement of the cuffed oropharyngeal airway (COPA), and to evaluate the effectiveness of the COPA in supporting positive pressure ventilation during anesthetic-induced apnea. DESIGN: Randomized, single-blinded study. SETTING: University hospital. PATIENTS: 60 ASA physical status I and II adult patients scheduled for elective surgery with general anesthesia. INTERVENTIONS: Patients were induced either with spontaneous inhalation of 5% sevoflurane or with propofol 2.0 mg/kg intravenously (i.v.) followed by a continuous infusion of 170 micrograms kg-1 min-1. If the propofol patient had a tight jaw in 90 seconds, additional propofol (0.5 mg/kg) was administered and the infusion rate was increased to 200 micrograms kg-1 min-1. The COPA was placed as soon as the jaw was sufficiently relaxed to allow its insertion into the mouth. MEASUREMENTS AND MAIN RESULTS: The median (range) time to the COPA placement were 90 seconds (30 to 150 sec) and 120 seconds (60 to 210 sec) with propofol and sevoflurane, respectively (p = 0.07, Mann-Whitney U-test). Unacceptable responses to the placement (3 or more coughs, vigorous or persistent [> 30 sec] movements) occurred in 23% and 17% of those who received propofol and sevoflurane, respectively, (p = 0.35. Chi-square test). All these responses were easily suppressed by additional doses of the assigned induction drug. After placement of the COPA, 53% (16/30) of the propofol patients had apnea lasting at least 30 seconds. Notably, the positive airway pressure at which a leak occurred in the mouth (pharyngeal leak pressure) was lower during this propofol-induced apnea than after the return of spontaneous breathing [9 (5 to 20) cmH2O vs. 15 (5 to 20) cmH2O, p < 0.01, Wilcoxon's signed-rank test]. In contrast, at no time were the sevoflurane patients apneic, and their pharyngeal leak pressure immediately following the placement was 12 (10 to 20) cmH2O. CONCLUSIONS: Propofol and sevoflurane are equally effective in facilitating the placement of the COPA. However, propofol often induces apnea, which is complicated by a less effective seal of the airway by the COPA against positive pressures. Because sevoflurane induction allows spontaneous respiration to continue and provides an adequate pharyngeal seal immediately following the placement of the COPA, it may be advantageous when apnea is not desired.

Adult↗
PubMed1999

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↗