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Biomedical subjects

A Tamura

Publications and source records attributed to A Tamura.

At least 55 records · Page 3Linked to original sources
PubMed2001

Immunohistochemical study of the phosphorylated and activated form of c-Jun NH2-terminal kinase in human aorta.

c-Jun NH2-terminal kinase is a key enzyme mediating the cellular response to a variety of extracellular stimuli. In the present study, we performed immunohistochemical studies of the expression of the phosphorylated form of the kinase in 51 human aortas of various ages. The phosphorylated kinase immunoreactivity was strongly detected in vascular smooth muscle cells of the medial vessel layer of atherosclerotic lesions from adults. Immunoreactivity was also strongly detected in similar cells of the intima. On the other hand, immunoreactive phosphorylated kinase was only weakly defected in the medial vascular smooth muscle cells of non-atherosclerotic lesions from adults. We also investigated the expression of the phosphorylated kinase in infant aortas. In contrast to its weak immunoreactivity in adult non-atherosclerotic lesions, the kinase immunoreactivity was detected in high amounts in vascular smooth muscle cells of non-atherosclerotic lesions from infants. Thus, the abundant expression of the phosphorylated kinase in these cells in atherosclerotic lesions of adults and non-atherosclerotic lesions of infants suggests that the activation of c-Jun NH2-terminal kinase may be an important element initiating the proliferation of vascular smooth muscle cells during atherogenesis and aortic development.

Adult↗
PubMed2001

Induction of lymphocyte apoptosis in rat liver allograft with ongoing rejection by FTY720.

The action mechanism of FTY720, a novel immunosuppressant, is completely different from conventional immunosuppressants. The drug, which triggers apoptosis in murine and human lymphocytes, has a potent immunosuppressive activity to prevent allograft rejection without any severe side-effect. The present study was designed to determine whether FTY720 induces apoptotic cell death in activated lymphocytes infiltrated into liver grafts with ongoing rejection. FTY720 was orally administered at 5 mg/kg to the recipients on day 3 and day 4 after grafting, when the graft rejection was histologically confirmed. The intragraft patterns of IL-2, interferon-gamma (IFN-gamma), perforin, and granzyme B gene expression were detected by reverse transcriptase-polymerase chain reaction. The treatment reversed ongoing rejection and significantly prolonged recipient survival time compared with the control group. Light microscopic observation of the graft sections stained with the DNA nick-end labelling method showed that the apoptosis in the control allografts was mainly induced in hepatocytes, while that in the FTY720-treated allografts was in infiltrated lymphocytes. The rejection therapy with FTY720 did not alter the expression of IL-2, IFN-gamma, and perforin mRNAs, but slightly decreased granzyme B expression. Our results suggest that FTY720 does not alter the intrinsic lymphocyte function to produce the rejection-related cytokines, but strongly induces apoptotic cell death in the activated lymphocytes. Thus, FTY720 affords new insight into the mechanisms underlying improvements in immunosuppressive treatments.

Animals↗
PubMed2001

Immunolocalisation of the janus kinases (JAK)--signal transducers and activators of transcription (STAT) pathway in human epidermis.

The janus kinases (JAK) and signal transducers and activators of the transcription (STAT) pathway have been shown to be activated by a number of cytokines or growth factors and to play significant roles in the differentiation of various cell types. In the present study, we investigated the distribution of the JAK-STAT pathway using immunohistochemistry in the human epidermis. Each element of the pathway showed abundant and differential expression in the epidermis. The differential distribution of the elements was most strikingly observed in the horny keratinised cell and granular layers of the epidermis. JAK2, JAK3, STAT1 and STAT5 were expressed in high amounts, and JAK1, TYK2, STAT2, STAT3, STAT4 and STAT6 to a much lesser extent in the horny cell layer. JAK3, TYK2, STAT2, STAT3, STAT4 and STAT6 were more abundantly expressed in the granular layer than the lower layers of the epidermis. JAK1, STAT1 and STAT5 were expressed at almost the same levels in the various layers of the epidermis. These results show that elements of the JAK-STAT pathway are abundantly and differentially expressed in the epidermis. It is suggested that each element of the pathway may play a role at a distinct stage of keratinocyte differentiation.

Adult↗
PubMed2001

Possible involvement of Fyn kinase in ethanol-stimulated Cas tyrosine phosphorylation in rat cerebellum and cerebral cortex.

In the present study, we have investigated the effect of intraperitoneal injection of ethanol (3.5 g/kg) on tyrosine phosphorylation in rat brain. Immunoblot analysis using an antiphosphotyrosine antibody revealed that a 130-kDa protein band was detected in the brain extract in response to ethanol administration. This ethanol-stimulated tyrosine phosphorylation of the 130-kDa protein was found in the brain but not in the heart, liver or thymus. The 130-kDa phosphotyrosine-containing protein was identified by immunoprecipitation to be Cas, a crk-associated src substrate. This ethanol-stimulated tyrosine phosphorylation of Cas was observed most prominently in the cerebellum and the cerebral cortex. We further examined the possible involvement of Fyn kinase in ethanol-stimulated Cas tyrosine phosphorylation. Immunecomplex kinase assay showed that Fyn was activated in the cerebellum and cerebral cortex of ethanol-administered rats. Immunoprecipitation experiments also showed that Fyn was co-immunoprecipitated with an anti-Cas antibody in these regions from ethanol-administered rats. Furthermore, exogenous Fyn was shown to phosphorylate Cas from cerebellum and cerebral cortex in vitro. These findings indicate that ethanol stimulates tyrosine phosphorylation of Cas in rat cerebellum and cerebral cortex, and that Fyn may be involved in the process.

Animals↗
PubMed2001

Clinical evaluation of Amplicor Mycobacterium detection system for the diagnosis of pulmonary mycobacterial infection using sputum.

SETTING: The Amplicor Mycobacterium detection kit was evaluated for the diagnosis of active pulmonary mycobacterial infection using sputum. OBJECTIVE: To assess the clinical usefulness of the Amplicor Mycobacterium kit for the diagnosis of pulmonary tuberculosis and non-tuberculous mycobacterial infection in the country of medium prevalence. DESIGN: All the patients were diagnosed with bacterial, histopathological, and clinical 'gold standard'. The sensitivity and specificity for diagnosing clinically active pulmonary tuberculosis and Mycobacterium avium and Mycobacterium intracellulare infections were evaluated comparing Amplicor results and clinical diagnosis. RESULTS: A total of 1088 sputum specimens were collected from 780 in and out patients. Mycobacteria were recovered from 339 specimens by culture. The sensitivity and specificity of conventional culture method for the diagnosis of pulmonary tuberculosis were 60.2% and 99.8% respectively based on the number of patients. The figures for Amplicor were 61.8% and 97.4% respectively. There was no statistical significant difference between these methods. In rapidity, the Amplicor was significantly superior to the microscopy method in sensitivity. CONCLUSION: Patients with Amplicor positive and conventional negative result had mostly mycobacteria related diseases. The Amplicor positive result indicated mostly active mycobacterial infection and was clinically useful for rapid diagnosis.

Chi-Square Distribution↗
PubMed2001

Immunolocalization of the mitogen-activated protein kinase signaling pathway in Hassall's corpuscles of the human thymus.

In the present study, we investigated the immunohistochemical localization of mitogen-activated protein kinase (MAPK) signaling pathway in the human thymus. Three members of MAPK, the extracellular signal-regulated kinase (ERK), the c-Jun N-terminal kinase (JNK) and the p38 kinase, showed differential expression patterns in the thymus medulla. The phosphorylated form of ERK (p-ERK) was abundantly present in the outer layer of Hassall's corpuscles, and the phosphorylated form of p38 kinase (p-p38 kinase) was present in the entire Hassall's corpuscles. The phosphorylated form of JNK (p-JNK) was expressed in medullary thymocytes. We also examined localization of MAPK kinases (MAPKK or MEK) which specifically activate MAPK. MEK1, an activator of ERK, was found in the outer layer of Hassall's corpuscles where p-ERK was expressed. MEK3, an activator of p38 kinase, was also expressed in the outer layer. MEK4 and MEK7, which are activators of JNK, were present in the entire Hassall's corpuscles. Thus, differential expression of MAPK in the thymus supports the concept that the MAPK signaling pathway controls the specificity of functional thymic responses to extracellular stimuli. Furthermore, the abundant expression of various elements of the pathway in Hassall's corpuscles suggests that the pathway is involved in thymic medullary epithelial maturation.

Child, Preschool↗
PubMed2001

Interleukin-1 or tumor necrosis factor-alpha augmented the cytotoxic effect of mycobacteria on human fibroblasts: application to evaluation of pathogenesis of clinical isolates of Mycobacterium tuberculosis and M. avium complex.

Mycobacteria-induced in vitro events reflecting human tuberculosis can contribute to the evaluation of the pathogenesis of Mycobacterium tuberculosis (MTB). In this study, we propose such an in vitro method based on live mycobacteria-induced cytotoxicity to human cell lines. When human lung-derived normal fibroblast cell line MRC-5 was infected with various strains of mycobacteria (M. tuberculosis H(37)Rv and H(37) Ra, Mycobacterium avium 427S and 2151SmO, and Mycobacterium bovis BCG Pasteur and Tokyo), the fibroblasts were killed by mycobacteria according to the degree of virulence. Other human originated macrophage (U-937, THP-1), myeloid (HL-60), and epithelial carcinoma (A549) cell lines exhibited a similar cytotoxic response to virulent mycobacteria. MRC-5 was most susceptible to virulent mycobacteria among various human cell lines examined. The cytotoxicity was enhanced by the proinflammatory cytokines, interleukin-1 (IL-1) and tumor necrosis factor-a (TNF-alpha), which in the absence of mycobacteria stimulate the growth of normal human fibroblasts. This in vitro evaluation system was applied to clinical isolates of drug-sensitive MTB (DS-MTB), drug-resistant MTB (DR-MTB) including multidrug-resistant (MDR-MTB), and M. avium complex (MAC). MTB strains (n = 24) exhibited strong cytotoxic activity, but MAC strains (n = 5) had only weak activity. Furthermore, there was no significant difference in cytotoxicity between DS-MTB (n = 11) and DR-MTB (n = 13). Collectively, these results suggest that this new in vitro system is useful for evaluating the pathogenesis of mycobacteria and that there was no difference in the pathogenesis between drug-susceptible and drug-resistant clinical isolates.

Cell Death↗
PubMed2001

Epidemiological survey of Orientia tsutsugamushi distribution in field rodents in Saitama Prefecture, Japan, and discovery of a new type.

There are various antigenic variants of Orientia tsutsugamushi which are distinguished by immunological and molecular genetic methods targeted at the antigenic diversity of 56-kDa type-specific antigen proteins. The present study was performed to analyze 15 strains successfully isolated from rodents in Saitama Prefecture, Japan, by 56-kDa gene sequence homologies, reactivities with type-specific monoclonal antibodies and polymerase chain reaction (PCR) using type-specific primer-pairs. We demonstrated the presence of a new type of O. tsutsugamushi among the isolates. This new type, designated as the Saitama type, was located in the branch of Karp type in the phylogenetic tree based on 56-kDa gene sequences, but distant from the known Karp types, such as Karp, JP-1 and JP-2, showing less than 90% homology. Strains of this type could not be distinguished by immunological methods from Karp type strains, but a new primer-pair for PCR which specifically amplifies the DNA of this new type strain was designed. This primer-pair may serve to find this strain type in future studies.

Animals↗
PubMed2001

Spontaneous normalization of negative T waves in infarct-related leads reflects improvement in left ventricular wall motion even in patients with persistent abnormal Q waves after anterior wall acute myocardial infarction.

This study aimed to clarify whether spontaneous T-wave normalization (TWN) in infarct-related leads reflects improvement in left ventricular (LV) wall motion even in patients with persistent abnormal Q waves after acute myocardial infarction (AMI). Eighty-five patients were classified into the following 3 groups: patients with Q-wave regression (group A, n = 21), those with persistent abnormal Q waves and TWN (group B, n = 36), and those with persistent abnormal Q waves and absence of TWN (group C, n = 28). Groups A and B had greater improvement in LV ejection fraction and regional wall motion between 1 and 6 months after AMI than group C. In conclusion, spontaneous TWN in the healing stage of anterior AMI reflects functional recovery of viable myocardium in the infarct region even in patients with persistent abnormal Q waves.

Aged↗
PubMed2001

Post-ischemic administration of DY-9760e, a novel calmodulin antagonist, reduced infarct volume in the permanent focal ischemia model of spontaneously hypertensive rat.

We assessed the effect of a novel calmodulin antagonist, DY-9760e (3-[2-[4-(3-chloro-2-methylphenyl)-1-piperazinyl]ethyl]-5,6-dimethoxy-1-(4-imidazolylmethyl)-1H-indazole dihydrochloride 3.5 hydrate) in a spontaneously hypertensive rat (SHR) permanent focal cerebral ischemia. In experiment I, the left middle cerebral artery was permanently occluded in 62 SHRs. DY-9760e (0.5 mg kg(-1) h(-1)) or vehicle alone were administered continuously i.v. for 6 h, beginning 0, 30, or 60 min after the arterial occlusion. The infarct volume was measured 24 h of ischemia. In experiment II, the effect of DY-9760e on CBF was assessed in 10 SHRs. Administration without a delay resulted in a mean infarct volume of 166.7 +/- 21.0 mm3 (vehicle; n = 10) and 125.1 +/- 31.8 mm3 (DY-9760e; n = 9). Administration with a 30 min delay resulted in a mean infarct volume of 173.2 +/- 32.4 mm3 (vehicle; n = 12) and 143.3 +/- 35.3 mm3 (DY-9760e; n = 11). Dy-9760e significantly reduced the infarct under these conditions (p < 0.05). The administration with a 60 min delay failed to reduce the infarct. DY-9760e had no effect on the CBF. Continuous i.v. administration of DY-9760e reduced infarct volume in a SHR permanent focal ischemia without affecting ischemic CBF.

Animals↗
PubMed2001

Relationship between terminal QRS distortion on the admission electrocardiogram and the time course of left ventricular wall motion in anterior wall acute myocardial infarction.

In order to clarify the time course of left ventricular (LV) wall motion in patients with anterior acute myocardial infarction (AMI) showing terminal QRS distortion on the admission electrocardiogram (ECG), the present study examined 106 patients with their first anterior AMI (< or =6 h) who underwent emergency coronary arteriography and cardiac cathetherization at 1 and 6 months after the infarction. The patients were classified into 2 groups according to the presence (group A, n=23) or absence (group B, n=83) of terminal QRS distortion (emergence of the J point at > or =50% of the R-wave amplitude in leads with QR configuration and/or absence of S waves in leads with RS configuration) on the admission ECG. Group A had a lower LV ejection fraction and more reduced regional wall motion (RWM) in the infarct region at both 1 and 6 months after AMI than group B. The degree of improvement in RWM between 1 and 6 months after AMI was less in group A than in group B (-0.1+/-0.5 vs 0.4+/-0.6 SD/chord, p<0.01). This study indicates that patients with anterior AMI showing terminal QRS distortion on the admission ECG have more severely depressed LV wall motion and less improvement in RWM in the infarct region in the healing stage, suggesting that this sign is an indicator of severe myocardial damage.

Aged↗
PubMed2001

Differential effects of activity and climate on onset of subarachnoid hemorrhage.

Conflicting findings of the effect of climate on onset of subarachnoid hemorrhage (SAH) may result from the influence of strenuous activities which can trigger aneurysmal rupture independent of climatological factors. The effect of climate and patient activities on onset of SAH were analyzed. The clinical records of 786 consecutive patients with aneurysmal SAH admitted to our hospital for 10 years were reviewed. Activities at onset were categorized according to the intensity of strain at onset. Seasonal variation, circannual cyclic trend, and association with 90 meteorological factors were examined in each category and the results were compared between categories. Bimonthly occurrence in the light strain group showed a significant seasonal variation and cyclic trend with two peaks in early spring and fall, whereas no significant trend was detected in the overall patients and in the heavy strain group. The significant meteorological factors were global solar radiation, sunshine hours, changes in mean and minimum temperature and mean vapor pressure from the previous day, and minimum pressure in the previous 7 days. Lower global solar radiation in the light strain group was associated with onset with the lowest p value (p = 0.0046). No factors were significant in the heavy strain group. There is some evidence of the possible influence of climatological factors on onset of SAH without strenuous activity. Strenuous activity seems to affect onset more strongly, which masks any effect of climate.

Adult↗
PubMed2001

[The causes of death in patients with non-MDR pulmonary tuberculosis in our hospital].

We studied the causes of death in 295 patients (mean (+/- SD) age 70.5 +/- 13.2 y.o.) with active non-MDR pulmonary tuberculosis who died in our hospital between 1991 and 1999. A hundred and twenty eight patients (43.4%, group A) died of tuberculosis, while 167 patients (56.6%) of other accompanying diseases. In 46 patients of the latter (15.6%, group B), pulmonary tuberculosis gave an unfavorable impact on their clinical course. In these patients the extent of pulmonary tuberculosis on chest roentgenograph was similar with the remaining 121 patients who also died of the accompanying diseases (41.0%, group C) and was less severe than those of the group A patients. Their nutritional conditions measured by serum albumin and choline-esterase level on admission, however, were as low as those of the group A patients and distinctly worse than those of the group C patients. Most patients of groups A and B died within 3 months after admission, while less than half patients of group C died during the same period. The age frequency distribution of the patients in groups B and C had a single peak in the age group 70 to 89, while that in group A showed two peaks, one similar peak as in groups B and C, and another peak in the age group 50 to 59. The numbers of homeless patients, of the patients with extensive cavitary lesions, and of the patients who died of ARDS (Adult Respiratory Distress Syndrome) or severe pneumothorax in group A were the most also in the age group 50 to 59, indicating that the patients' delay in admitting to hospitals was the major cause of high motality in this age group. As to detailed causes of death in group A, patients died of respiratory failure (32 cases), emaciation (28 cases), progression of pulmonary tuberculosis (20 cases), ARDS (15 cases), tuberculosis-related diseases such as pneumothorax, hemoptysis, and DIC (24 cases). In groups B and C patients died of organ failure (36 cases), infectious diseases (33 cases) and malignancy (30 cases). The total number of died patients has increased, and the proportion of cases dying of ARDS and infectious diseases has increased statistically significantly recently.

Adult↗
PubMed2001

Astrocytic swelling in the ipsilateral substantia nigra after occlusion of the middle cerebral artery in rats.

BACKGROUND AND PURPOSE: Focal cerebral ischemia results in neuronal changes in remote areas that have fiber connections with the ischemic area. We reported previously that a high-signal-intensity lesion was observed in the substantia nigra after striatal infarction on T2-weighted MR images in both clinical and experimental cases. However, the origin of these changes in signal intensity remains unclear. The aim of this study was to investigate the nigral changes by examining the correlation between the apparent diffusion coefficient (ADC) and the tissue structure. METHODS: Sprague-Dawley rats were subjected to middle cerebral artery occlusion. Four days after the occlusion, when T2-weighted images revealed the presence of an area of high signal intensity in the ipsilateral substantia nigra, diffusion-weighted imaging was performed using a 4.7-T superconductive MR unit, and the ADCs were calculated and imaged. Histopathologic examination by both light and electron microscopy was performed on day 4 after surgery. RESULTS: Diffusion-weighted images showed an area of high signal intensity in the ipsilateral substantia nigra, and the ADC map revealed uniform reduction of the ADC in this area. Swelling of astrocytic end-feet was observed, especially in the pars reticulata. CONCLUSION: These findings suggest that MR changes in the ipsilateral substantia nigra after striatal injury consist mainly of swelling in the astrocytic end-feet.

Animals↗
PubMed2001

[A study on the clinical features of pulmonary tuberculosis in elderly patients].

The clinical findings of pulmonary tuberculosis in elderly patients aged 75 years of age or older (elderly group) were compared with the middle-aged patients aged between 45 and 54 years of age (middle-aged group) and the young patients aged 34 years of age or younger (young group). The elderly patients who died in hospital were also compared with the elderly patients who survived. Study subjects were culture-positive pulmonary tuberculosis patients who were discharged from our hospital from December 1996 to November 1998. There were 79 patients in the elderly group, 95 in the middle-aged group, and 88 in the young group. The results were as follows. 1) The male/female ratio was significantly lower in the elderly group (1.9:1) than the middle-aged group (6.9:1). 2) Complication was noted more frequently in the elderly group. However, diabetes mellitus was noted less frequently in the elderly group (12.7%) than the middle-aged group (28.4%). 3) The frequency of cavitation was lower in the elderly group (59.5%) than the middle-aged group (87.4%). 4) The fever over 38 degrees C was noted less frequently in the elderly group (17.7%) than the other groups, while the frequency of the fever over 37 degrees C showed no significant difference between the elderly group and the other groups. 5) The frequencies of hypoalbuminemia and appetite loss were higher in the elderly group than the other groups. 6) The elderly group showed high mortality rate of 31.6%. The complication with cerebrovascular disease was noted significantly higher in the patients who died in hospital than those who survived. The frequency of widespread infiltrates, fever over 38 degrees C, neutrophilia, hypoalbuminemia and appetite loss were all significantly higher in the patients who died in hospital while their sputa were still positive on culture than those who survived. Our study clearly showed the features of elderly pulmonary tuberculosis patients in comparison with middle-aged patients and young patients. These features are very important to suspect the diagnosis of pulmonary tuberculosis in elderly patients with some atypical manifestation. Our study also suggests that the delay in diagnosing tuberculosis causes more frequently the patients' deterioration and death in elderly patients than in middle-aged patients and young patients.

Adult↗
PubMed2001

[HIV seroprevalence in patients with tuberculosis].

The number of patients co-infected with human immunodeficiency virus (HIV) and tuberculosis (TB) in our hospital is increasing year after year. Although most patients were HIV tested because of miliary tuberculosis or extra-pulmonary tuberculosis, some patients were found HIV seropositive by chance. In order to determine the incidence of HIV seropositivity among TB patients, HIV testing was carried out in TB patients for two years from January 1998 with the consent of patients. TB patients who received anti-HIV antibody examination were 164 in 1998, and 149 in 1999 and among them HIV seropositive TB patients were 4 in 1998 and 6 in 1999. The incidence of HIV seropositivity was 3.2% in all TB patients, 28.6% in miliary TB patients, and 1.0% in typical TB patients. The number of patients co-infected with HIV and TB in Tokyo was estimated by using these HIV seropositivity, it was 23 cases/year among miliary TB patients and 16 cases/year among typical TB patients. As there were many HIV-infected persons and many TB patients in Tokyo, it was thought that HIV testing in TB patients was important for the early detection of HIV infection and the early initiation of HIV treatment.

Adolescent↗
PubMed2000

Lethal forebrain ischemia stimulates sphingomyelin hydrolysis and ceramide generation in the gerbil hippocampus.

Ceramide, a hydrolyzed product of sphingomyelin, is reported to play an important role in apoptosis. In this study, we measured the sphingomyelin and ceramide levels in the hippocampus of the gerbil after transient forebrain ischemia for 5 min (lethal) or 2 min (sublethal). The aim was to examine alterations in the sphingomyelin cycle during delayed neuronal death, which we considered could be due to apoptosis. Sphingolipids were separated on high-performance thin-layer chromatography plates and analyzed by gas-liquid chromatography. At 30 min and 24 h after lethal ischemia, sphingomyelin levels were decreased and ceramide levels were increased compared with control levels. No significant changes were observed after sublethal ischemia. These results suggest that the sphingomyelin cycle may have a role in neuronal death.

Animals↗