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Biomedical subjects

I Nakamura

Publications and source records attributed to I Nakamura.

At least 253 records · Page 14Linked to original sources
PubMed1988

Familial ataxia with abnormal CSF, with special reference to an autopsy case from three affected siblings.

We report here the clinical features of 3 affected siblings and neuropathological findings of the CNS from an autopsied case among them. Their common clinical features consisted of cerebellar ataxia and tremors through movements and postures. Two of the 3 siblings showed autonomic abnormalities, hard-of-hearing, pyramidal sign and areflexia. Then they always had xanthochromia and an elevated protein without pleocytosis in their CSFs. Neuropathologically, intracytoplasmic eosinophilic inclusion bodies were found in the neurons of some restricted nuclei or nerve cell groups of the brain stem, cerebellum and spinal cord. Similar bodies appeared also in glial, ependymal and choroid plexus epithelial cells. Such eosinophilic bodies are thought to consist of protein-rich substances from histochemical properties, and result from an unknown inherited metabolic error.

Adult↗
PubMed1988

Positive reaction in mouse ligated intestinal loop assay with nonenterotoxigenic and nonhemolytic strains of Staphylococcus aureus.

Nonenterotoxigenic and nonhemolytic strains of Staphylococcus aureus exhibited a positive reaction in the mouse intestinal loop assay except for a strain negative for the egg yolk reaction. Edema and swelling in all positive loops, increased bacterial cell numbers within intestinal loops, and extremely close adhesion to or inclusion of numerous bacterial cells in HeLa cells after inoculation of the strains were observed. These results suggest a possible invasive ability of the strains.

Animals↗
PubMed1988

Myocardial mechanical and myosin isoenzyme alterations in streptozotocin-diabetic rats.

Fifteen week old male Wistar rats (n = 7) were made diabetic by intravenous injection of streptozotocin (50 mg/kg). Age-matched, untreated male Wistar rats (n = 9) served as controls. Hearts were removed after 5-6 weeks of diabetes, and the isometric developed tension (T) of isolated left ventricular papillary muscles and its first derivative (dT/dt) were measured at a frequency of 0.2 Hz. During testing, the muscles were perfused with Tyrode's solution (Ca2+ concentration was half of normal Tyrode's solution, pH 7.4, 32 degrees C, bubbled with 95% O2 and 5% CO2). In addition, the left ventricular isoenzyme pattern, which is related to myocardial energetics, was determined by pyrophosphate gel electrophoresis. There was no significant difference in isometric developed tension between diabetic and control rats (DM: 2.90 +/- 0.89 vs controls: 2.87 +/- 0.85 g/mm2, mean +/- SD), but in diabetic rats, dT/dtmax decreased significantly as compared with controls (DM: 23.5 +/- 4.2 vs controls: 31.9 +/- 7.9 g/mm2.s, p less than 0.05). Myocardial mechanical responses to isoproterenol (10(-7)M) and dibutyryl cyclic AMP (10(-5)M) also decreased in diabetic rats. The left ventricular myosin isoenzyme pattern shifted toward VM-3 in diabetic rats (VM-3: DM: 74.9 +/- 10.7 vs controls: 9.5 +/- 4.1%, p less than 0.001). These results indicate that diabetes influences myocardial contractility and changes cardiac energetics. Post-receptor processes may play a role in myocardial mechanical responses to catecholamines in streptozotocin-diabetic rats.

Animals↗
PubMed1988

Effects of bunitrolol on myocardial contractility and left ventricular myosin isoenzyme pattern.

Effects of long term treatment of hypertension with bunitrolol on myocardial contractility and left ventricular myosin isoenzyme pattern were examined. Male 22-week-old spontaneously hypertensive rats were treated with bunitrolol (30-40 mg/kg/d, p.o.) for 8-10 weeks. The blood pressure of the bunitrolol-treated group did not differ from that of the untreated group, but ratio of ventricular weight to body weight was significantly lower in the treated group. There were no significant differences in isometric developed tension and dT/dtmax of isolated left ventricular papillary muscles between bunitrolol-treated and control groups. Myocardial mechanical responses to isoprenaline (isoproterenol) also showed no differences between the two groups. Left ventricular myosin isoenzyme pattern obtained by pyrophosphate gel electrophoresis was significantly shifted to VM-1 by bunitrolol treatment.

Animals↗
PubMed1987

Lateral reticular nucleus neurons sending their axons to the contralateral inferior cerebellar peduncle. A horseradish peroxidase study in the rat.

The lateral reticular nucleus of the medulla oblongata (LRN) in the rat was observed after injecting horseradish peroxidase (HRP) bilaterally into the anterior lobe of the cerebellum; the inferior cerebellar peduncle had been cut unilaterally prior to the HRP injections. HRP-labeled neurons were seen bilaterally in the LRN; 89% in the contralateral, and 11% in the side ipsilateral to the pedunculotomy. The labeled neurons in the LRN ipsilateral to the pedunculotomy were assumed to send their axons to the anterior lobe of the cerebellum via the controlateral inferior cerebellar peduncle. Of these neurons, 60, 11 and 29% were distributed in the magnocellular, subtrigeminal and parvicellular divisions of the LRN, respectively.

Animals↗
PubMed1987

Defective differentiation of natural killer cells in SJL mice. Role of the thymus.

As previously shown, three distinct phenotypes exist in murine natural killer (NK) cell activity when it is evaluated by the endogenous levels of activity and the susceptibility to augmentation by interferon (IFN) and IFN inducers. The "low" phenotype has low levels of activity which can be poorly augmented by IFN, as in mice of SJL strain. The "inducible" phenotype exhibits low endogenous levels but can vigorously respond to IFN-mediated augmentation, as in A.SW strain. The "high" NK phenotype shows high levels of endogenous activity which can be augmented to still higher levels by IFN, as in B10.S mice. Since SJL mice with congenital absence of the thymus (nude) were of the inducible type, the effect of neonatal thymectomy was examined in the present study. Neonatal thymectomy was found to convert the low phenotype of SJL mice to the inducible, mimicking the effect of nu/nu genotype. Thymectomy as late as 25 days after birth was effective, but retransplantation of a syngeneic newborn or adult thymus, or thymocytes, failed to reverse the effect of thymectomy. The poor responsiveness of NK activity to IFN in SJL, therefore, is extrinsic to the NK cell lineage and is attributable to suppression or maturational block of NK cell differentiation by the thymus during the first few weeks of neonatal life. A series of experiments with bone marrow chimeras showed that the SJL recipients did not allow the expression of inducible or high phenotype by bone marrow progenitors from allogeneic donors with either phenotype. Therefore, the SJL recipients provide an environment which suppresses not only the development of IFN-sensitive NK cell precursors, but also the levels of endogenous NK cell activity. SJL bone marrow cells gave rise to NK activity of inducible phenotype in B10.S recipients, confirming the crucial role of the environment in which NK cell differentiation takes place.

Animals↗
PubMed1987

Class I H-2Db determinants are not involved in hybrid resistance to parental H-2b/Hh-1b bone marrow allograft.

Hybrid resistance to parental H-2b bone marrow grafts is directed to a cell surface structure controlled by the Hh-1 locus in or near the H-2D region. The nature of this surface structure is not known. Since homozygosity at the class I H-2D locus or loci in this haplotype would seem a necessary but not sufficient condition for the grafts' susceptibility to resistance, we tested whether the expression of this phenotype is dependent on the expression of class I H-2Db determinants. Cloned variants of H-2b tumor RBL-5 were obtained by immunoselection for the absence of H-2Db expression, as determined by the inability to bind specific antibody and to induce or react with alloreactive cytotoxic T lymphocytes. The three clones used in this study were H-2Db negative but H-2Kb positive and were natural killer cell resistant. When tested in vivo as competitive inhibitors the variant cells were capable of blocking hybrid resistance to parental H-2b bone marrow grafts as were unselected H-2Db-positive parental line cells. Therefore, H-2Db expression is irrelevant for Hh-1b expression. An incidental observation was that YAC-1 cells, a non-H-2b tumor with pronounced susceptibility to natural killing, were able to block hybrid resistance. This reactivity, not observed in our previous studies, raises the possibility that at least some of the effector cells are cross-reactive or capable of dual recognition.

Animals↗
PubMed1987

Myocardial contractility and left ventricular myosin isoenzyme pattern in cardiac hypertrophy due to chronic volume overload.

Chronic volume overloaded cardiac hypertrophy was induced by abdominal arteriovenous shunt in 10-week-old male Wistar rats. Ten weeks after the operation, myocardial mechanical examination was performed with isolated left ventricular papillary muscles. Left ventricular myosin isoenzyme pattern was also examined by pyrophosphate gel electrophoresis. In addition, morphological study by electron microscope was performed. In arteriovenous shunt rats, isometric developed tension (T) and its first derivative (dT/dt) were decreased, resting tension (RT) was increased and time to peak tension (TPT) was prolonged as compared to sham-operated control rats (T: 2.4 +/- 0.5 vs 2.8 +/- 0.8 g/mm2, NS. dT/dt: 23.9 +/- 4.8 vs 31.9 +/- 7.0 g/mm2.s, p less than 0.05. RT: 1.2 +/- 0.2 vs 0.9 +/- 0.1 g/mm2, p less than 0.05. TPT: 151.7 +/- 20.2 vs 128.3 +/- 10.3 msec, p less than 0.05). Myocardial mechanical responses to isoproterenol (10(-7) mol/l) and dibutyryl cyclic AMP (10(-5) mol/l) were both depressed in hypertrophied myocardium, although not significant statistically. Left ventricular myosin isoenzyme pattern was shifted towards VM-3 by chronic volume overload. Electron microscope study revealed increased collagen content in hypertrophied myocardium.

Adenosine Triphosphatases↗
PubMed1987

Genetic control of the target structures recognized in hybrid resistance.

Hybrid resistance of lethally irradiated (C57BL/6 X DBA/2)F1 and (C57BL/10 X C3H)F1 hybrid mice to the engraftment of parental C57BL/6 or C57BL/10 bone marrow cells is controlled by the H-2-linked Hh-1 locus. This resistance can be specifically blocked or inhibited by the injection of irradiated spleen cells from lethally irradiated, marrow reconstituted donor mice of certain strains. By testing the ability of regenerating spleen cells from various donor strains to block the resistance, we studied the genetic requirements for the expression of putative cell-surface structures recognized in hybrid resistance to H-2b marrow cells. Strains of mice bearing informative intra-H-2 or H-2/Qa-Tla recombinant haplotypes provided evidence that the Hh-1 locus is located telomeric to the H-2S region complement loci and centromeric to the H-2D region class I locus in the H-2b chromosome. Two mutations that affect the class I H-2Db gene have no effect on Hh-1b gene expression. The H-2D region of the H-2s haplotype contains an allele of the Hh-1 locus indistinguishable from that of the H-2Db region, as judged by the phenotypes of relevant strains and F1 hybrids. Collectively these data indicate that the Hh-1 locus is distinct from the class I H-2D (L) locus in the H-2b or H-2s genome, and favor the view that the expression or recognition of the relevant determinants is not associated with class I gene products.

Alleles↗