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Biomedical subjects

A Tamura

Publications and source records attributed to A Tamura.

At least 289 records · Page 16Linked to original sources
PubMed1994

Electron microscopic study of the distribution and the vertical transmission of Rickettsia tsutsugamushi in Leptotrombidium pallidum.

Leptotrombidium pallidum naturally infected with Rickettsia tsutsugamushi was reared and bred in our laboratory for several generations by brother and sister mating. The larvae and adults at the 8th and 9th generations were sectioned and observed by electron microscopy for analysis for the distribution of rickettsiae in the mites. The distribution densities of rickettsiae were markedly different among organs in each mite, but rickettsiae were seen in all the organs and tissues. Rickettsiae were distributed in the highest density in the salivary gland of larvae, and in the salivary gland, excretory bladder, epidermal layer, ovary and testis of adult mites. Only a few rickettsiae were recognized in the muscle of both larvae and adults. On the other hand, we found, in the infected family line used, a significant number of mites in which no rickettsiae were found by electron microscopy. The grouping of rickettsia-positive and -negative mites according to the parent family revealed that the efficiency of vertical transmission of rickettsia was different from one parent family to another. Thus, it became clear that a significant number of rickettsia-negative mites are produced in an infected family line.

Animals↗
PubMed1994

[Lung pathology of cryptococcosis].

To elucidate the relationship between the clinical manifestations and pathologic findings of the lung in patients with cryptococcosis, we reviewed 14 autopsied cases of cryptococcosis. Five patients had pulmonary cryptococcosis and 9 had disseminated cryptococcosis. Patients with pulmonary cryptococcosis showed granulomatous reactions of the lung, such as fibrocaseous cryptococcoma (n = 2), discrete granuloma (n = 2), and granulomatous pneumonia (n = 1). Patients with disseminated cryptococcosis showed intracapillary/interstitial involvement (n = 2), mucoid pneumonia (n = 3), histiocytic pneumonia (n = 1), and granulomatous pneumonia (n = 3). There was a distinct difference between pulmonary cryptococcosis and disseminated cryptococcosis in lung pathology. Intracapillary/interstitial involvement and mucoid pneumonia were fatal because of extensive hematogeneous dissemination to other organs. Hilar lymph node involvement of cryptococcosis was found in all of the nine patients with disseminated cryptococcosis and in one of the five patients with pulmonary cryptococcosis. Pleural involvement of cryptococcosis was found in six of the nine patients with disseminated cryptococcosis. We conclude that the clinical manifestations of cryptococcosis are closely associated with the variety of lung pathology of cryptococcosis. Clinicians should understand the morphologic features to cope with patients with cryptococcosis.

Adult↗
PubMed1994

A marked decrease in defensin mRNA in the only case of congenital neutrophil-specific granule deficiency reported in Japan.

A deficiency of defensins (human neutrophil peptides, HNP) has been previously demonstrated in two individuals with congenital neutrophil-specific granule deficiency (SGD), but its genetic basis is not well understood. We have studied another case of SGD, the only case reported in Japan, to elucidate the molecular basis of defensin deficiency. Using Western blot analysis, we showed for the first time that HNP-4, a novel human defensin, was also deficient in the patient's neutrophils. Northern blot analysis demonstrated that the defensin mRNA was absent in the bone marrow cells of the patient. Limited Southern blot analysis, using a defensin cDNA probe, did not reveal any differences in fragment patterns of the genomic DNA between the patient and the control. We propose that the defensin deficiency in our patient is a consequence of a marked decrease in defensin mRNA in neutrophil precursors. Our findings were consistent with a previous speculation suggesting that the SGD defect occurs at the level of transcription.

Adult↗
PubMed1993

Cholesterol in remnant-like lipoproteins in human serum using monoclonal anti apo B-100 and anti apo A-I immunoaffinity mixed gels.

We have developed a simple, rapid assay method for apo E-rich lipoproteins (d < 1.006 g/ml), using an immunoaffinity gel mixture of anti apo B-100 and apo A-I antibodies coupled to Sepharose 4B. The immunoaffinity mixed gels adsorb normal lipoproteins containing apo A-I quantitatively as well as most lipoproteins containing apo B-100. Unbound lipoproteins are quantified by assay of cholesterol. Characterization of the unbound lipoproteins of d < 1.006 g/ml (J Lipid Res 1992; 33: 369-380) has shown that they represent chylomicron and VLDL remnant-like particles (RLP). RLP-Cholesterol(C) levels in plasma have been determined in 363 male and female normolipidemic subjects (mean +/- S.D.: 72 +/- 16 mg/l) and have been found to be higher in patients with coronary heart disease and familial dysbetalipoproteinemia. Triglyceride-rich lipoproteins may well contain both atherogenic and non-atherogenic particles that can be separated by this simple immunoadsorption assay.

Adolescent↗
PubMed1993

Stimulatory effect of phospholipase A2 treatment on glucose utilization in human erythrocytes.

We examined whether modification of membrane phospholipids of human erythrocytes by hydrolysis with phospholipase A2 (PLA2 from bee venom) would affect glucose utilization, chosen as a typical model of intracellular metabolism, and, if so, intended to clarify the mechanism of the alteration of glycolysis. Treatment of erythrocytes with PLA2 induced a marked shape change (i.e., crenation) and significantly increased the rate of lactate production from glucose. Available evidence indicated that there is no relevance of this cell-shape change to the alteration of glycolysis. The lack of a detectable effect of papain treatment on glycolysis in PLA2-treated cells suggested that the increase in glycolysis by PLA2 treatment might not be caused by the conformational change of band-3 protein through modulation of membrane phospholipids. The result of the measurement of lactate production in the presence and absence of ouabain did not support the idea that hydrolysis of phospholipids by PLA2 treatment makes plasma membranes leaky to Na+ and consequently enhances glycolysis through activation of Na+/K(+)-ATPase. The action of PLA2 on glycolysis was abolished by extraction of free fatty acids in the cell membrane with bovine serum albumin. Loading erythrocytes with free fatty acid (oleic acid, linoleic acid, or arachidonic acid) caused a significant increase in glycolysis. Analysis of glycolytic intermediates suggested that the enhancement of glycolysis was induced by activation of 6-phosphofructokinase. The data, thus, indicate that treatment of human erythrocytes with PLA2 significantly accelerates glucose utilization and suggest that the stimulation of glycolysis is caused by activation of 6-phosphofructokinase through liberation of free fatty acids of membrane phospholipids by PLA2.

Adult↗
PubMed1993

Early recovery of protein synthesis following ischemia in hippocampal neurons with induced tolerance in the gerbil.

Following brief cerebral ischemia, tolerance to subsequent ischemia is induced in the hippocampal neurons. In this experiment, recovery of protein synthesis was investigated autoradiographically in gerbils with induced tolerance. The animals were subjected to single forebrain ischemia for 5 min (5-min ischemia group) or 2 min (2-min ischemia group). To observe the effect of tolerance acquisition, double forebrain ischemia (double ischemia group), 2-min ischemia followed by 5-min ischemia was induced 2 days later. At various recirculation periods (90 min, 6 h, 1 day, and 4 days following ischemia), animals received a single dose of L-[2,3-3H]valine. In the 5-min ischemia group, protein synthesis in the CA1 sector was severely suppressed during the period from 90 min to 1 day of recirculation and never returned to the normal level even at 4 day of recirculation. In the 2-min ischemia group, protein synthesis recovered gradually and returned to near normal at 4 days of recirculation. On the other hand, in the double ischemia group, recovery of protein synthesis in the CA1 sector was rapid. At 1 day of recirculation, protein synthesis returned to near normal. Protein synthesis in the CA2 sector was inhibited during the 4 days of recirculation in this group. The present study revealed an early recovery of protein synthesis in the hippocampal CA1 neurons in the gerbil with induced tolerance. We suggest that recovery of protein synthesis is essential for the survival of neurons exposed to transient ischemia.

Amino Acids↗
PubMed1993

Expression of the large myelin-associated glycoprotein isoform in rat oligodendrocytes around cerebral infarcts.

An immunohistochemical method that uses two specific antisera-distinguishable myelin-associated glycoprotein (MAG) isoforms showed an expression of large MAG isoform (L-MAG) protein in the oligodendrocyte cytoplasms in the white matter around experimental cerebral infarcts produced by occlusion of the left middle cerebral artery in the rat. L-MAG protein also was detected in the white matter on the contralateral side. This protein appears prior to S-MAG protein in myelination and remyelination in the central and peripheral nervous systems, and is believed to function in myelin formation. Because L-MAG protein has been found in the oligodendrocyte cytoplasm only in the early development period, its appearance in this cytoplasm after ischemic insult is evidence of MAG regeneration.

Animals↗
PubMed1993

Hemostatic changes induced by percutaneous mitral valvuloplasty.

A study was conducted of hemostatic changes in 15 patients with mild-to-moderate rheumatic mitral stenosis who underwent percutaneous mitral balloon valvuloplasty (PMV). The patients were divided into two groups according to the degree of valve dilatation as evaluated by Doppler echocardiography before and 2 to 3 months after therapy: one group (n = 7) with suboptimal valvuloplasty (< 0.5 cm2) and one (n = 8) with optimal valvuloplasty (> or = 0.5 cm2). On the day of echocardiographic evaluation, hemostatic testing of the platelet, coagulation, and fibrinolytic systems was performed. Before PMV there were no differences in the hemodynamic and hemostatic variables between the two groups. No favorable hemostatic changes were achieved by PMV in the suboptimal group. In the optimal group, however, platelet-specific protein levels decreased after PMV; the mean levels of platelet factor 4 and beta-thromboglobulin were moderately elevated before and decreased after PMV from 38.5 +/- 22.2 to 8.13 +/- 5.08 ng/ml (p < 0.01) and from 132.5 +/- 78.6 to 38.8 +/- 19.5 ng/ml (p < 0.02), respectively. Coagulation and fibrinolytic systems were unchanged in this study. These data indicate that PMV produces favorable hemostatic effects when sufficient mitral valve dilatation is achieved. Analysis of our data also discloses that platelet activation plays an important role in the initial step of thrombus formation in patients with rheumatic mitral stenosis.

Blood Coagulation Tests↗
PubMed1993

Interaction of subtilisin BPN' and recombinant Streptomyces subtilisin inhibitors with substituted P1 site residues.

Kinetic analysis was performed on the interaction between subtilisin BPN' and recombinant species of a proteinaceous proteinase inhibitor, Streptomyces subtilisin inhibitor (SSI), of which the P1 site amino acid residue, Met73, was replaced by site-directed mutagenesis. The inhibitor constant, Ki, was determined from the residual enzyme activity by using a peptide substrate. The rate constant of binding, kon, and the rate constant of dissociation, koff, were determined from a progress curve of the substrate hydrolysis in the presence of the inhibitor by using newly derived equations. A recombinant SSI in which Met73 was replaced by Ile showed an affinity (1/Ki) toward subtilisin BPN' of only about 7% of that of the wild-type SSI, and the kinetic analysis revealed that the increase of koff was responsible for this difference. The affinity of other SSI mutants in which Met73 was replaced by Glu or Asp decreased significantly as pH became increasingly alkaline. The decrease in the affinity of these recombinants was due to the decrease of kon rather than the increase of koff. Stopped-flow studies revealed that the binding reaction was reconcilable with a two-step mechanism, and the kinetic parameters for each step were obtained for the binding of the enzyme and recombinant SSIs.

Bacterial Proteins↗
PubMed1993

Long QT syndrome with insulin-dependent diabetes mellitus: contiguous gene syndrome on chromosome 11p.

Long QT syndrome (Romano-Ward syndrome) and insulin-dependent diabetes mellitus (IDDM) have been documented as being linked with gene(s) on chromosome 11p although concurrence of the two disorders has not been reported. Our case is a 13-year-old boy with Romano-Ward syndrome accompanied by IDDM. The long QT syndrome seemed to be transmitted in an autosomal-dominant mode because the Q-T intervals of his father and paternal grandfather were longer than normal. There was no family member with an abnormally high level of blood glucose except the patient. The human leucocyte antigen (HLA) haplotypes of the patient and the father were DR4/DR9 and DR2/DR9, respectively. This study suggests that in our patient IDDM, as well as Romano-Ward syndrome, is linked with chromosome 11p in the presence of HLA-DR4. The results support the previous study that chromosome 11p encodes a gene implicated in HLA-DR4-dependent diabetes susceptibility.

Child↗
PubMed1993

A nationwide survey of seasonal affective disorder at 53 outpatient university clinics in Japan.

A nationwide survey of seasonal affective disorder (SAD) was performed from autumn 1990 to spring 1991 with the cooperation of 53 outpatient university psychiatric clinics in Japan. Forty-six SAD patients were identified among 5265 depressed outpatients. SAD was generally reported to occur in 1-3% of the depressed outpatients newly attending each facility. Hours of sunshine were found to be a more relevant variable influencing the prevalence of SAD than latitude or the mean temperature in December. The unexpectedly low percentage (20-30%) of SAD patients with atypical vegetative symptoms suggests that SAD patients who have no prior knowledge of SAD and those who are recruited via the media have different vegetative symptom profiles.

Adult↗
PubMed1993

Two-step polymerase chain reaction for diagnosis of scrub typhus and identification of antigenic variants of Rickettsia tsutsugamushi.

Two-step polymerase chain reaction (nested PCR) method was examined for the diagnosis of scrub typhus. Primers were derived from the type-specific antigen (TSA) gene DNA sequences of Rickettsia tsutsugamushi, Gilliam strain. These primers served to produce rickettsia-specific products in the amplification of template DNA prepared from all serovariants, Gilliam, Karp, Kato, Kawasaki, Kuroki and Shimokoshi strains, and the fragments of product after digestion with several kinds of restriction endonuclease showed the respective patterns to strain in acrylamide or agarose gel electrophoresis. The rickettsia-specific DNAs were also derived, by this nested PCR, by amplifying DNA from patients' bloods and mites from endemic areas, and the serotype of rickettsiae infected to these hosts could be identified from fragment patterns of the amplified products observed after endonuclease treatment. These results indicate that this PCR is sensitive and specific method not only for detection of rickettsial DNA in patient specimens and in mites, but also for the typing of rickettsiae infected to these hosts.

Animals↗
PubMed1993

Structures of enzymatically modified products of arbekacin by methicillin-resistant. Staphylococcus aureus.

Only a limited number of strains of methicillin-resistant Staphylococcus aureus (MRSA) moderately resistant to arbekacin (ABK) have been isolated clinically. Three inactivated products of ABK have been obtained by reaction with excess amounts of a crude enzyme preparation extracted from an ABK-resistant MRSA strain (MIC, 25 micrograms/ml). The 2"-O-phosphate was the major product together with small amounts of the 6'-N-acetate and the double modification product. The structures of these modification products were determined by MS and NMR spectral analyses.

Aminoglycosides↗
PubMed1993

[Pulmonary tumor embolism: relationship between clinical manifestations and pathologic findings].

To elucidate the relationship between the clinical manifestations and pathologic findings in pulmonary tumor embolism, we reviewed the autopsy and clinical records of 318 patients who died of various cancers, excluding lung cancer. Sixty-seven (21%) of the patients had at least one tumor embolus in the pulmonary arteries and 12 (3.8%) had multiple tumor emboli contributing to death. We considered that the 12 patients (6 with hepatoma, 3 with gastric cancer, and one each with colon cancer, pelvic cancer, and cervical cancer) had disease defined as pulmonary tumor embolism, and we fully analyzed these cases. Patients with hepatoma had manifestations of submassive pulmonary thromboembolism and patients with other cancers had manifestations of pulmonary microthromboembolism. The lungs of all of the 6 patients with hepatoma had both microscopic and macroscopic tumor emboli and 3 cases were accompanied by pulmonary infarction. On the other hand, the lungs of all of the remaining 6 patients had microscopic (including intracapillary) tumor emboli and 4 cases were accompanied by diffuse alveolar damage. The lung of 1 of the patients with hepatoma and 2 of the patients with other cancers also had pulmonary tumor thrombotic microangiopathy. In patients with hepatoma, the tumor emboli seemed to be derived from tumor invasion to large veins, while the tumor emboli seemed to be derived from widespread tumor invasion to lymphatic channels in the remaining patients. The authors conclude that pulmonary tumor embolism shows heterogeneous manifestations such as acute and subacute cor pulmonale and diffuse alveolar damage. Clinicians should keep in mind that the heterogeneity of the disease is closely associated with the varieties of malignancies and their spread.

Adenocarcinoma↗