Search PubMed⌕ Search

Biomedical subjects

S Takagi

Publications and source records attributed to S Takagi.

At least 145 records · Page 8Linked to original sources
PubMed1999

Ventricular fibrillation and shortening, alternans and after-depolarizations of epicardial monophasic action potentials during coronary occlusion and reperfusion: effect of repetition of ischemia.

The relationship between the occurrence of ventricular fibrillation (VF) and repolarization abnormalities of the ischemic and reperfused myocardium is poorly understood. The present study examined the temporal relationship between ischemia- and reperfusion-induced changes in monophasic action potential (MAP) configurations and the occurrence of VF, and assessed the effects of repetition of ischemia. The left anterior descending coronary artery of 32 anesthetized dogs was occluded twice for 5 min, 30 min apart, during constant atrial pacing while recording MAPs from the epicardial ischemic zone. During the first occlusion, shortening of the MAP duration at 90% repolarization (APD90) and an increase in MAP alternans, defined as the maximal difference in APD90 between 2 consecutive beats, were observed. Afterdepolarizations also occurred transiently in 35% of the animals during occlusion and in 29% upon reperfusion. VF occurred in 28% (9/32 of the dogs) during the first sequence, and the incidence was higher in the subgroups with maximal alternans > or =20 ms (p<0.05), maximal shortening rate > or =30%, and afterdepolarizations. During the second sequence, the incidence of VF was reduced to 9% (3/32, p<0.05), associated with a significant reduction in the MAP changes. Thus, repolarization abnormalities of the ischemic and reperfused myocardium appear to be related to the occurrence of VF. The amelioration of the repolarization abnormalities by repetition of ischemia may be involved in its antifibrillatory effect.

Action Potentials↗
PubMed1999

Gadolinium suppresses stretch-induced increases in the differences in epicardial and endocardial monophasic action potential durations and ventricular arrhythmias in dogs.

We tested whether acute pressure overloading of the left ventricle (LV) had spatially different effects on repolarization, thereby causing arrhythmias. The effects of gadolinium (Gd3+), a nonspecific blocker of stretch-activated channels were also examined. In anesthetized dogs, 5 s clamping of the ascending aorta (AC), separated by 5-min intervals, was repeated while monophasic action potentials (MAPs) were recorded from the LV endocardium and epicardium. Gd3+ was injected into the left atrium before the second (500 micromol) and third AC (2500 micromol) (n=10). In a separate group (n=7), the effects of Gd3+ in the presence of verapamil were examined. Epicardial MAP durations at 50% and 90% repolarization (APD50; APD90) shortened in response to LV pressure rise and elongation of the segment length induced by the first AC, whereas endocardial MAP durations remained unchanged. Thus, the difference in APD50 and APD90 increased. Consistent with these changes, premature ventricular contractions (PVCs) developed. Gd3+ had no effect on baseline MAP durations, however it prevented an AC-induced increase in the difference by suppressing epicardial MAP shortening. Gd3+ also reduced PVCs in a dose-dependent manner at plasma concentrations of 1-4 micromol/L. The effects were also evident after administration of verapamil. Thus, gadolinium suppressed an increase in the spatial dispersion of repolarization and arrhythmias via a mechanism of action different from that of verapamil.

Action Potentials↗
PubMed1999

Ki-1 (CD30)-positive anaplastic large cell lymphoma, sarcomatoid variant accompanied by spontaneously regressing lymphadenopathy.

Although it has been reported that primary Ki-1 (CD30)-positive anaplastic large cell lymphoma (ALCL) of the skin may undergo spontaneous regression, it is rare for ALCL without cutaneous involvement to have spontaneously regressing lymphadenopathy. We report a case of sarcomatoid variant of ALCL accompanied by spontaneously regressing lymphadenopathy. The patient had gastric and pulmonary involvement of ALCL in addition to systemic lymphadenopathy, but with no cutaneous involvement. The lymphadenopathy spontaneously improved gradually during a period of one month without any treatment. At the same time, multiple small nodules in both lung fields decreased on chest computed tomography and multiple elevated gastric tumors with dimples were endoscopically recognized to have improved. He has since been treated with combination chemotherapy because of recurrence of the lymphadenopathy.

Adult↗
PubMed1999

[Prognosis predictor of chronic-stage acute myocardial infarction].

An investigation of acute myocardial infarction (AMI) was performed in Obihiro City, Hokkaido from October 1.1990 to March 31.1996. Based on the recorded cases, we conducted an investigation on the progress of 194 survivors by questionnaires, and we investigated the factors affecting long-term prognosis of AMI. The mean follow-up period was 1.62 years. The mean age at onset and frequency of hypertension were higher in women than in men. On the other hand, a larger percentage of men smoked and drank alcohol. Kaplan-Meier analysis showed that survival was strongly influenced by aging, drinking, prior history of AMI or stroke, renal dysfunction, cardiac failure and early rehabilitation. Using Cox's hazard model, it was found that mortality risk increases 1) by 1.5 times for an increase of 10 years in age (2.6-times higher for people over 65 years old), 2) by 2.5 times for people with a history of AMI or stroke, 3) by 4.6 times for people with renal dysfunction, and 4) by 5.7 times for people with cardiac failure of Killip class III or IV. On the other hand, it was found that mortality risk decreases 1) by 0.3 times for people who drink alcohol, 2) by 0.1 times for people who have undergone PTCA, and 3) by 0.3 times for people who have undergone rehabilitation. The mortality risk is high for people who do not drink alcohol and those who have not undergone rehabilitation using Cox's hazard model adjusted all those factors. In conclusion, prognostic predictor in chronic-stage acute myocardial infarction are aging, drinking, prior history of AMI or stroke, renal dysfunction, cardiac failure, early rehabilitation, and PTCA. The results also indicated that, regardless of the historical and clinical characteristics, early rehabilitation is very important to increase the probability of long-term survival.

Aged↗
PubMed1999

[Effectiveness of Nd: YAG laser therapy on Japanese cedar pollinosis].

Many have reported on the effectiveness of laser surgery therapy for perennial allergic rhinitis. However, the suppressive effects of laser irradiation on allergic rhinitis and its symptoms have not been reported in patients with pollinosis. This is because therapeutic effects on pollinosis are difficult to evaluate. The amount of pollen in the air varies during the year, and from year to year. Also, allergic symptoms develop due to exposure to the amount of pollen which is markedly influenced by the weather. In this study, the severity of allergic symptoms in the pollen season was compared between patients treated with early medication, non-treated patients and patients treated with preseasonal contact Nd: YAG laser surgery. Results suggests that laser surgery was effective in reducing the severity of symptoms in patients with cedar pollinosis. Symptoms were milder in the laser group than in the medication group and non-treated group for 3-4 weeks after the start of seasonal pollinosis, although no differences were noted in the early weeks. This may be explained by the fact that laser irradiation reduces the lamina propria of the nasal mucosa, the site of allergic reactions. This also suggests that allergic pollen can't penetrate the mucosal surface which shows squamous epithelization after laser irradiation.

Adult↗
PubMed1999

[PET evaluation of glucose metabolism in cancer].

Accelerated glycolysis is one of the biochemical characteristics of cancer cells. Based on this fact, positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) has been used in the diagnosis of various cancers. After intravenous injection of FDG and PET scans, most cancers are identified by high FDG accumulation. This metabolic tumor imaging method has been used successfully in the differentiation of benign and malignant tumors, in the diagnosis of metastasis or recurrence, in the detection of primary unknown cancers, and in cancer screening. Because the degree of FDG accumulation reflects tumor glucose consumption, quantification of FDG uptake by PET can be used in predicting biological malignancy and in monitoring treatment in both radiation and chemotherapy. The potential utility of Glut-1 and hexokinase, reported to be responsible for increased glucose metabolism, as biological markers of cancers is yet to be determined.

Cancer Care Facilities↗
PubMed1999

[Typical thymic carcinoid tumor with multiple metastases diagnosed by pleural effusion cytology].

A 57-year-old man was referred and admitted to our hospital because of anterior mediastinal tumors and pericardial effusion. Although his condition had been diagnosed as thymic cancer by another hospital, a cytologic examination of pleural effusion specimens obtained a positive stain for chromogranin A, and yielded a diagnosis of thymic carcinoid tumor with multiple metastases. Despite irradiation and relief therapy, the patient died 8 months later. A histopathologic examination of the thymic tumor at autopsy revealed typical carcinoid patterns. The cytologic examination proved capable of accurately diagnosing the carcinoid tumor. Although such tumors are usually considered to have a good prognosis, unfavorable outcomes are also a possibility, as was demonstrated in this case.

Carcinoid Tumor↗
PubMed1999

Iatrogenic gallbladder perforation during laparoscopic cholecystectomy: etiology and sequelae.

Iatrogenic perforation of the gallbladder (PGB) during laparoscopic cholecystectomy (LC) leads to spillage of bile and gallstones into the peritoneal cavity, which can result in serious postoperative infection. The objective of this study is to prospectively evaluate with long-term follow-up the risk factors, mechanisms, and complications associated with PGB in patients undergoing LC. Data from 1412 patients undergoing LC were collected prospectively between 1989 and 1995. Patients with and without iatrogenic gallbladder perforation were compared. Long-term follow-up was obtained using mailed questionnaires and telephone interviews, when needed. Of the 1412 patients, 512 (36%) sustained a PGB. Male sex, weight, gallbladder inflammation, thickening of the gallbladder, presence of adhesions, and a difficult hilar dissection were all associated with an increased incidence of PGB. The most common mechanisms of PGB were laceration due to grasper traction (55%) and electrocautery dissection (40%). Both the operating time and length of hospital stay were significantly longer in the PGB group. No difference was observed in the rate of wound infections between PGB and non-PGB patients (1.6% versus 1.8%). Only one patient (with an inflamed and perforated gallbladder) developed an early postoperative intra-abdominal abscess. Long-term follow-up averaging 48 months was achieved with a response rate of 44 per cent. No late intra-abdominal abscesses or complications attributable to retained gallstones were discovered.

Cholecystectomy, Laparoscopic↗
PubMed1999

Virulence factors of Helicobacter pylori affecting its gastric colonization in Mongolian gerbils.

Helicobacter pylori is recognized to possess a number of virulence factors. We investigated the role of motility, vacuolating cytotoxin, and urease in gastric colonization by H. pylori. Mongolian gerbils (SPF, 7 weeks old) were challenged orally with a single administration of a 24-h culture broth of H. pylori and then were killed 6 and 26 weeks after challenge. Gastric colonization, severe gastritis, ulceration, and high levels of serum anti-H. pylori immunoglobulin G were observed in the gerbils challenged with strains motile in the semisolid medium (ATCC43504, HPY-127, HPY-204), but not in gerbils challenged with strains nonmotile in the medium (ATCC49503, HPY-205, HPY-206). Only strains ATCC43504, ATCC49503, HPY-204, and HPY-206 had vacuolating cytotoxin activity against HeLa and Vero cells. Thus, motile strains were able to colonize regardless of their vacuolating cytotoxin activities, and vacuolating cytotoxin was not associated with epithelial damage in the gastric mucosa. Furthermore, the phenotypic variants of strains with the ability to colonize that lacked either motility or urease activity lost their ability to colonize. In conclusion, motility and urease activity, but not vacuolating cytotoxin activity, are essential for gastric colonization by H. pylori in Mongolian gerbils.

Animals↗
PubMed1998

Studies on removal efficiency of chloroform from tap water by rice bran.

Removal efficiency of chloroform from tap water by rice bran was investigated. The adsorption rate by rice bran was similar to activated carbon. The amount of chloroform adsorbed was plotted against the equilibrium concentration of chloroform in solution on a logarithmic scale. A linear relationship was obtained, indicating that the adsorption reaction was a Freundlich type. The adsorption of chloroform by rice bran was observed in the range of pH 1-11. Chloroform was successfully removed from tap water with average removal efficiency of 70% after 60 min when rice bran was applied to tap water that contained 0.0064 mg/L chloroform.

Adsorption↗
PubMed1998

Magnetic resonance imaging and 11C-N-methylspiperone/positron emission tomography studies in a patient with the interval form of carbon monoxide poisoning.

Magnetic resonance (MR) and (11)C-N-methylspiperone ((11)C-NMSP)/positron emission tomography (PET) imagings were repeatedly performed in a 50-year-old man with the interval form of carbon monoxide (CO) poisoning. In MR images obtained when delayed neuropsychiatric symptoms developed (two months after poisoning), the inner segments of the bilateral globus pallidus appeared as high signal intensities in the T1-weighted and low signal intensities in the T2-weighted images, suggesting prior focal hemorrhage in these areas. A PET study with (11)C-NMSP performed at that time showed an increase in dopamine D2 receptor binding in the caudate and putamen. Treatment with bromocriptine was very effective and five months after the poisoning, MR and (11)C-NMSP/PET images showed improvement, concomitantly with the disappearance of the neuropsychiatric symptoms.

Basal Ganglia↗
PubMed1998

Identification of single C motif-1/lymphotactin receptor XCR1.

Single C motif-1 (SCM-1)/lymphotactin is a member of the chemokine superfamily, but retains only the 2nd and 4th of the four cysteine residues conserved in other chemokines. In humans, there are two highly homologous SCM-1 genes encoding SCM-1alpha and SCM-1beta with two amino acid substitutions. To identify a specific receptor for SCM-1 proteins, we produced recombinant SCM-1alpha and SCM-1beta by the baculovirus expression system and tested them on murine L1.2 cells stably expressing eight known chemokine receptors and three orphan receptors. Both proteins specifically induced migration in cells expressing an orphan receptor, GPR5. The migration was chemotactic and suppressed by pertussis toxin, indicating coupling to a Galpha type of G protein. Both proteins also induced intracellular calcium mobilization in GPR5-expressing L1.2 cells with efficient mutual cross desensitization. SCM-1alpha bound specifically to GPR5-expressing L1.2 cells with a Kd of 10 nM. By Northern blot analysis, GPR5 mRNA of about 5 kilobases was detected strongly in placenta and weakly in spleen and thymus among various human tissues. Identification of a specific receptor for SCM-1 would facilitate our investigation on its biological function. Following the set rule for the chemokine receptor nomenclature, we propose to designate GPR5 as XCR1 from XC chemokine receptor-1.

Animals↗