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Biomedical subjects

A Tamura

Publications and source records attributed to A Tamura.

At least 253 records · Page 14Linked to original sources
PubMed1995

Significant discrepancies between van't Hoff and calorimetric enthalpies.

In this paper we show that the usual assumption in studies of the temperature variation of equilibrium constants for equilibria of the form A+B <-->AB that a plot of ln K vs. 1/T (K = equilibrium constant, T = temperature in degrees kelvin) is a straight line with slope equal to -delta HvH/R (delta HvH = van't Hoff or apparent enthalpy, R = gas constant) is not valid in many cases. In all the cases considered here, delta HvH is temperature dependent and is significantly different from the true or calorimetrically measured enthalpy, and the respective values for delta Cp are also significantly different.

Calorimetry↗
PubMed1995

Phylogenetic position of Rickettsia tsutsugamushi and the relationship among its antigenic variants by analyses of 16S rRNA gene sequences.

The 16S rRNA gene sequences of Rickettsia tsutsugamushi and Rickettsia sibirica were determined by PCR and DNA sequencing. Phylogenetic analysis revealed that R. sibirica is positioned in a cluster of the genus Rickettsia with a similarity value of 98.1-99.6%, whereas R. tsutsugamushi is located apart from the cluster with a similarity value of 90.2-90.6%. This evidence suggests that R. tsutsugamushi should be excluded taxonomically from the genus Rickettsia. The phylogenetic classification of six antigenic variants in R. tsutsugamushi moderately reflected their antigenic relationship known in closely and distantly related strains.

Antigens, Bacterial↗
PubMed1995

Regional diastolic function in effort angina pectoris: assessment with biplane left ventriculography.

To investigate left ventricular (LV) regional diastolic function in effort angina pectoris (AP), we performed left ventriculography in 14 patients with AP and isolated left anterior descending artery disease and in 9 normal subjects (N). LV volume (V), regional area (S) [anterior, apex, and inferior], and the first derivative of V and S (dV/dt, dS/dt) were derived from analysis of the left ventriculogram. Normalized peak filling rate (nPFR) and peak atrial filling rate (nPAFR) were derived from dV/dt. The ratio of filling volume to stroke volume during rapid filling and atrial contraction were defined as rapid filling fraction (RFF) and atrial filling fraction (AFF). Similarly, peak area changing rate (PACR), peak area changing rate during atrial contraction (PACRac), rapid area changing fraction (RACF), and atrial area changing fraction (AACF) were derived from S and dS/dt. We also calculated the time constant of LV relaxation (T), and LV global and regional compliance during atrial contraction [(dV/VdP)ac, (dS/SdP)ac]. The LV global diastolic function (T increases, nPFR decreases) was impaired in the angina patients. LV regional diastolic function (nPACR decreases, RACF decreases) was also impaired in the affected region of the AP group. While their rapid filling was impaired, nPACRac was maintained and AACF was increased in the affected region. Furthermore, nPACR and RACF each showed a significant inverse correlation with AACF in the anterior region [r = -0.57 (P < 0.01), r = -0.92 (P < 0.001)]. In the affected region of the patients with AP, (dS/SdP)ac was increased, but not significantly. Thus, LV global and regional diastolic functions were simultaneously impaired in patients with isolated left anterior descending artery disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Long-term spatial cognitive impairment after middle cerebral artery occlusion in rats: no involvement of the hippocampus.

The behavioral and neurochemical changes in the chronic phase of permanent occlusion of the right middle cerebral artery (MCA) in rats were investigated. One month after MCA occlusion, 23 rats were unable to solve a radial eight-arm maze task during an entire 1-month period, whereas seven rats were able to solve this task. Three months after occlusion, 19 MCA-occluded rats failed to solve the task successfully again for at least 1 month (the cognitively impaired rats), whereas 11 MCA-occluded rats were able to solve it (the cognitively unimpaired rats). The rats that underwent behavioral testing were examined for any changes in the acetylcholine (ACh) levels in the hippocampus using HPLC with electrochemical detection or the formation of long-term potentiation (LTP) in the population spike of the hippocampal CA1 field. The immunohistochemical distribution of either the microtubule-associated protein 2 (MAP2) or glial fibrillary acidic protein (GFAP) in the hippocampus of the cognitively impaired rats was also studied. In the cognitively impaired rats, neither the suppression of the induction of LTP, nor the degradation of MAP2, nor the increase in the GFAP immunoreactivity was observed in the hippocampus. The levels of ACh in the hippocampus did not change significantly among the cognitively impaired, unimpaired, and the sham-operated rats. These results suggest that MCA occlusion is capable of producing long-term spatial cognitive disturbance in rats without any evidence of neurobiological damage in the hippocampus.

Acetylcholine↗
PubMed1995

The neuroprotective effect of the novel noncompetitive NMDA antagonist, FR115427 in focal cerebral ischemia in rats.

The present study was carried out to compare the neuroprotective effect of the novel noncompetitive NMDA antagonist, FR115427, with that of(+)MK-801 in rat focal cerebral ischemia. Focal cerebral ischemia was produced by permanent occlusion of the left middle cerebral artery (MCA). Drugs were administered intraperitoneally immediately after ischemia and once a day for 6 successive days. FR115427 (10 mg/kg, i.p.) significantly improved neurologic deficit at 1 day after ischemia and reduced total infarct volume (54%) at 7 days after ischemia. Although FR115427 (10 mg/kg, s.c.) produced neuronal vacuolization similar to (+)MK-801, FR115427 did not produce adverse effects such as a loss of body weight, mortality, and hypothermia, in contrast to (+)MK-801. These results suggest that FR115427 may be useful in the treatment of stroke.

Animals↗
PubMed1995

Long-term spatial cognitive impairment following middle cerebral artery occlusion in rats. A behavioral study.

Behavioral changes in the chronic phase of permanent occlusion of the right middle cerebral artery (MCA) in rats were investigated. One month after MCA occlusion, 23 rats were unable and 7 rats were able to solve a radial 8-arm maze task during a 1-month period. Three months after occlusion, 19 MCA-occluded rats failed to solve the task successfully again during at least a 1-month period (the cognitively impaired rats), and 11 MCA-occluded rats were able to solve it (the cognitively unimpaired rats). When a delay of 60 min was imposed for this task, five cognitively unimpaired rats failed to solve it. The locomotor activity of the cognitively impaired rats increased significantly 2 months after occlusion, and this increase showed good correlation with spatial cognitive deficit. However, the mean time a rat spent at each arm remained unchanged among the cognitively impaired, unimpaired, and sham-operated rats. There was no significant difference in the ratio between the cognitively impaired and unimpaired rats for disturbed motor coordination. These results suggest that MCA occlusion is capable of producing long-term spatial cognitive disturbance in rats. In addition, this spatial cognitive deficit does not seem to be primarily due to hypermotility or a disturbance in motor coordination.

Animals↗
PubMed1995

Inferior ST segment depression as a useful marker for identifying proximal left anterior descending artery occlusion during acute anterior myocardial infarction.

To determine whether or not ST segment deviation on admission electrocardiograms can identify patients with anterior acute myocardial infarction due to proximal left anterior descending artery occlusion, the magnitude and location of ST segment elevation or depression were compared between patients with proximal left anterior descending artery occlusion (group A, n = 47) and those with distal left anterior descending artery occlusion (group B, n = 59). ST segment depression in each of the inferior leads was significantly greater in group A than in group B. The incidence of ST segment depression > or = 1 mm in each of the inferior leads (II; 81% vs 27%, III; 85% vs 54%, aVF; 87% vs 47%, P < 0.01) was significantly higher in group A than in group B. In addition, the incidence of ST segment depression > or = 1 mm in all of the inferior leads was significantly greater in group A than in group B (77% vs 22%, P < 0.01). In group A, maximal ST segment elevation was more frequent in lead V2 alone (43% vs 14%, P < 0.01). Group A had greater ST segment elevation in lead aVL than group B, and the incidence of ST segment elevation > or = 1 mm in lead aVL was significantly higher in group A than in group B (66% vs 47%, P < 0.05). ST segment depression > or = 1 mm in all of the inferior leads was most valuable for identifying group A patients (77% sensitivity and 78% specificity). In contrast, the maximal ST segment elevation in lead V2 alone or ST segment elevation > or = 1 mm in lead aVL had a low diagnostic value (43% sensitivity and 86% specificity, 66% sensitivity and 53% specificity, respectively). In conclusion, this study indicates that analysis of ST segment deviation in the inferior leads is useful for identifying patients with acute anterior myocardial infarction due to proximal left anterior descending occlusion.

Adult↗
PubMed1995

Occupational scleroderma. A 17-year follow-up study.

Two patients with a scleroderma-like disorder induced by epoxy resins were reported from the Department of Dermatology, Gunma University School of Medicine, Japan in 1980. Here, we describe the clinical and laboratory characteristics of these patients after 17 years' follow-up from 1976 to 1993. Their systemic manifestations and indurated sclerotic skin changes disappeared within 5 years. No internal organ involvement has developed during the period of follow-up. On routine laboratory tests, no abnormalities have been found in the peripheral blood or in the blood chemistry or serology. Histological examination revealed atrophy of the dermis and restoration of the normal pattern of fine collagen bundles, when compared with the previous skin biopsy specimens. This scleroderma-like disorder induced by epoxy resins is considered to be different from systemic sclerosis: it has an acute onset and a fairly good prognosis, and does not show involvement of the internal organs.

Adult↗
PubMed1995

Alveolar basement membrane breaks down in diffuse alveolar damage: an immunohistochemical study.

Sequential structural changes of the alveoli in diffuse alveolar damage (DAD) were examined by immunohistochemical methods. Lung specimens obtained at autopsy from 52 patients with DAD were stained with antibodies to laminin, 7S collagen (7S) and type IV collagen (type IV) for alveolar basement membrane, to von Willebrand factor, CD-31 and thrombomodulin (TM) for the alveolar capillary endothelial cell, and to epithelial membrane antigen and surfactant apo-protein (PE-10) for the alveolar epithelium. Forty-two of the patients had the exudative form of DAD; 10 of the patients had the proliferative form of DAD. The results were summarized as follows: (i) laminin was most easily impaired both in the epithelial and capillary basement membrane in the early exudative stage; (ii) following laminin, 7S and type IV in the capillary basement membrane were also injured in the early exudative stage, and recovered in the proliferative stage; (iii) subsequently, 7S and type IV in the epithelial basement membrane were also impaired in the late exudative stage, and remained impaired even in the proliferative stage; and (iv) alveolar epithelium regenerated almost completely in the late exudative stage, but staining for TM in the alveolar capillary recovered in the proliferative stage. Because the alveolar basement membrane must govern the homeostasis of alveolar tissue architecture, it was concluded that its preservation is necessary to avoid the abnormal remodeling of the alveoli in the reparative stage of DAD, if the patient survives the acute episodes of the disease.

Adolescent↗
PubMed1995

Serum lipoprotein(a) concentrations are related to coronary disease progression without new myocardial infarction.

OBJECTIVE: To examine the association between serum lipoprotein(a) and angiographically assessed coronary artery disease progression without new myocardial infarction. PATIENTS AND DESIGN: 85 patients with coronary artery disease who underwent serial angiography with an interval of at least two years were studied. Progression of coronary artery disease was defined as an increase in diameter stenosis of 15% or more. Vessels on which angioplasty had been performed were excluded from the analysis. The patients were classified into two groups: a progression group without new myocardial infarction (n = 48) and non-progression group (n = 37). Risk factors including lipoprotein(a) were evaluated to see how they were related to progression without myocardial infarction. RESULTS: There were no differences between the two groups in the following factors: age, gender, the time interval between the angiographic studies, the distribution of the analysed coronary arteries, and history of well established coronary risk factors. Univariate analysis showed that serum lipoprotein(a) (P = 0.0002), cigarette smoking between the studies (P = 0.002), serum high density lipoprotein (P = 0.003), and serum low density lipoprotein (P = 0.01) were related to progression without myocardial infarction. Multivariate analysis selected two independent factors for progression without myocardial infarction: serum lipoprotein(a) (P = 0.003) and serum high density lipoprotein (P = 0.03). CONCLUSIONS: Serum lipoprotein(a) concentrations are closely related to the progression of coronary artery disease without new myocardial infarction. Lipoprotein(a) lowering treatment may be needed to prevent disease progression in patients with coronary artery disease and high serum lipoprotein(a).

Aged↗
PubMed1995

Clinical significance of inferior ST elevation during acute anterior myocardial infarction.

OBJECTIVES: To clarify the genesis and clinical significance of inferior ST elevation during acute anterior myocardial infarction. PATIENTS AND DESIGN: A total of 106 patients with first acute anterior myocardial infarction (< or = 6 h) were divided into two groups according to the presence (group A, n = 12) or absence (group B, n = 94) of ST elevation of > or = 1 mm in at least two of the inferior leads on the admission electrocardiogram. RESULTS: On admission electrocardiograms, group A had a smaller summed ST deviation in the lateral limb leads than group B. On emergency coronary arteriograms, the incidence of a wrapped left anterior descending artery was higher in group A than in group B (100% v 27%, P < 0.01). The incidence of occlusion of a left anterior descending artery distal to its first diagonal branch was higher in group A than in group B (100% v 46%, P < 0.01). Peak serum creatine kinase activity and in-hospital mortality tended to be lower in group A than in group B. Group A had better left ventricular ejection fraction and regional wall motion in the anterobasal and anterolateral regions in the chronic phase than group B. In contrast, regional wall motion in the diaphragmatic region was reduced to a greater extent in group A than in group B. CONCLUSIONS: Inferior ST elevation during acute anterior myocardial infarction appears only in the presence of a combination of a lesser degree of transmural ischaemic myocardium in the anterobasal and anterolateral wall together with transmural ischaemic myocardium in the inferior wall; in all cases there was occlusion of a wrapped left anterior descending artery distal to its first diagonal branch. Patients with such an ST elevation appear to have a better in-hospital prognosis than those without it.

Coronary Angiography↗
PubMed1995

Reduction of serum cholesterol levels alters lesional composition of atherosclerotic plaques. Effect of pravastatin sodium on atherosclerosis in mature WHHL rabbits.

We examined whether serum cholesterol reduction alters the lesional composition of atherosclerotic plaques. To reduce serum cholesterol levels, we gave pravastatin sodium, a 3-hydroxy-3-methylglutaryl Coenzyme A reductase inhibitor, to mature Watanabe heritable hyperlipidemic rabbits, an LDL receptor-deficient animal model, for 48 weeks. Atherosclerotic lesions were immunohistochemically and conventionally stained and each lesional component area was measured by a color image analyzer. Compared with those of a placebo group, serum LDL cholesterol levels were reduced by 22% (P<.05). Data for atherosclerosis indicated a significant decrease in percent of surface lesion area (26% reduction) and in intimal thickening (30% reduction) in the abdominal aorta, as well as in coronary stenosis (29% reduction). Data for lesional composition indicated a significant decrease in the percent area of macrophage plus extracellular lipid deposits in aortic lesions (32% reduction) and coronary lesions (45% reduction). A significant increase was observed in the percent area of collagen in aortic lesions and in the percent area of smooth muscle cells in coronary lesions. The plaques seemed to become stable lesions as a result of pravastatin treatment. In conclusion, a long-term reduction of serum LDL cholesterol reduced lipid-related lesional components, in addition to suppressing the progression of established atherosclerosis.

Animals↗
PubMed1995

[Suppressive effects of iodinated contrast media on human platelet aggregation].

Suppressive effects of several iodinated contrast media on stimulus-induced aggregation of human platelets were demonstrated. All contrast media, including ionic (iothalamate and ioxaglate) and non-ionic ones (iohexol, ioversol and iopamidol), suppressed the collagen- and thrombin-induced aggregation in a concentration-dependent manner. The effects of the former were much stronger than those of the latter. With ioxaglate, a similar inhibitory effect was also observed on PAF- and U46619-stimulated aggregation. The suppressive effect of ioxaglate on collagen-stimulated aggregation almost disappeared upon dilution of the medium with the platelet-poor plasma, suggesting that the effect is reversible.

Collagen↗
PubMed1995

Posterior pituitary hematoma in a case of posttraumatic diabetes insipidus. Case report.

A 28-year-old man presented with diabetes insipidus (DI) 10 days after basilar skull fracture without brain injury. Magnetic resonance (MR) imaging revealed a hematoma in the posterior lobe of the pituitary gland but no lesions in the hypothalamus or pituitary stalk. The patient's DI continued for 2 months at which time transsphenoidal surgery was performed to decompress the cystic hematoma with persistent mass effect. The DI attenuated shortly after the surgery and the patient became completely free from DI 5 months later. Although hemorrhage into the posterior lobe is one of the frequent pathological changes in fatal head-injury victims and secondary DI in these cases has usually been thought to be acute and transient, the true incidence and natural course of the posterior pituitary hemorrhage and subsequent DI in nonfatal head-injury patients are totally unknown. In this article, the authors present the first demonstration on MR imaging of a posterior pituitary hematoma in a patient with head injury. The authors propose that serial MR imaging is an important diagnostic tool in patients with posttraumatic DI because some of them may harbor pituitary hematoma and because decompression surgery may prevent transition to permanent DI, especially in cases when the mass effect is persistent due to a cystic change in the hematoma.

Acute Disease↗