Biomedical subjects

I Nakamura

Publications and source records attributed to I Nakamura.

At least 181 records · Page 10Linked to original sources

PubMed1994

Salt preference elicited by chronic intracerebroventricular angiotensin II.

1. Much more water was consumed than either 0.9% or 2.7% saline in response to various dipsogenic stimuli in untreated normal replete rats when they had free access to water, 0.9% and 2.7% saline. On the other hand, the rats drank more 0.9% saline than water and 2.7% saline when each solution is the sole drinking fluid offered. 2. A marked increase in preference for 0.9% saline was observed during the chronic i.c.v. injection of angiotensin II at a dose of 25 ng/hr for 7 consecutive days in the three bottle choice test. After the cessation of angiotensin II infusion, most rats (45 out of 50 rats) returned to drink much more water than 0.9% and 2.7% saline, similar to the drinking pattern of the 0.9% saline-treated control rats. However, some rats (5 out of 50 rats) still preferred 0.9% saline and this persisted for up to 3 months although these rats did not show a hypertensive state and an increase of plasma renin activity.

Angiotensin II↗

PubMed1994

Effects of delapril hydrochloride on the myocardium of spontaneously hypertensive rats.

OBJECTIVE: To investigate the effects of long term treatment with delapril hydrochloride (an angiotensin-converting enzyme inhibitor) on myocardial contractility and ventricular myosin isoenzymes in spontaneously hypertensive rats (SHR). DESIGN: Delapril hydrochloride (10 mg/kg/day by mouth) was administered to 22- to 24-week-old male SHR for eight to 10 weeks. The isometric contractions of isolated left ventricular papillary muscles were observed while being perfused with Tyrode's solution (32 degrees C, pH 7.4, bubbled with 95% oxygen: 5% carbon dioxide, stimulation frequency 0.2 Hz). The left ventricular myosin isoenzymes were separated using pyrophosphate-gel electrophoresis. MAIN RESULTS: The mean systolic blood pressure of the delapril-treated group was significantly lower than that of the untreated control group. The mean ventricular weight was also lower in the delapril-treated than control group (mean +/- SD, untreated: 211 +/- 11 mmHg, n = 6; delapril-treated: 183 +/- 14 mmHg, n = 8, P < 0.01). The mean isometric developed tension (T) and +/-dT/dtmax of isolated left ventricular papillary muscles from the delapril-treated and untreated SHR did not differ significantly. The left ventricular myosin isoenzyme pattern obtained by pyrophosphate-gel electrophoresis, however, showed a significant shift towards VM-1 after long term delapril treatment. CONCLUSIONS: Long term treatment of SHR with delapril hydrochloride reduced blood pressure, which was associated with regression of cardiac hypertrophy, and changed the ventricular myosin isoenzyme pattern without significantly affecting myocardial contractility.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1993

Myocardial contractility and energetics in cardiac hypertrophy and its regression.

The changes in myocardial contractility and ventricular myosin isoenzymes were investigated in rats with pressure-overload cardiac hypertrophy as well as during its regression. Hypertrophic myocardium was obtained from rats with renovascular hypertension (Goldblatt rats), rats with abdominal aortic constriction (AC), and spontaneously hypertensive rats (SHR). Regression of cardiac hypertrophy was induced by lowering the blood pressure through nephrectomy on the affected side in Goldblatt rats, by opening the clip which constricted the abdominal aorta in AC rats, and by the administration of antihypertensive agents to SHR. The isometric developed tension of isolated left ventricular papillary muscles and the maximum rate of increase in the tension (dT/dtmax) were measured. Left ventricular myosin isoenzymes were separated by pyrophosphate gel electrophoresis. Isometric developed tension remained unchanged, but dT/dtmax was decreased in hypertrophic myocardium, although it recovered along with the regression of cardiac hypertrophy. The left ventricular myosin isoenzyme pattern was shifted towards V3 in hypertrophic myocardium, and shifted back again towards V1 with the regression of cardiac hypertrophy. These results indicate that relief of hemodynamic overload is one of the most important elements in the regression of cardiac hypertrophy and the associated physiological or biochemical alterations. However, other factors such as neurohumoral influences must also be taken into consideration.

Animals↗

PubMed1993

Water-soluble chymotrypsin specific inhibitors containing arginine.

In an attempt to develop water-soluble, potent inhibitors for chymotrypsin, structurally rigid dipeptides containing arginine were designed and synthesized. The dipeptide H-D-Arg-Phe-NHBzl inhibited chymotrypsin very strongly (Ki = 5.9 microM). The dipeptide with the inverse sequence, H-D-Phe-Arg-NHBzl, was also a moderate inhibitor for chymotrypsin with Ki of 240 microM. In spite of the presence of arginine in these dipeptides, they inhibited trypsin only weakly, indicating that they are highly specific for chymotrypsin. High resolution 1H-NMR (400-MHz) indicated that these dipeptides can make a strong intramolecular hydrophobic interaction between Arg-beta, gamma, delta-methylenes and Phe-phenyl, producing a rigid hydrophobic core which interacts with the chymotrypsin S2 site. Since these dipeptides are easily soluble in water, they are regarded as the sophisticated and effective inhibitors for chymotrypsin.

Amino Acid Sequence↗

PubMed1993

Mitochondrial DNA deletion in human myocardium.

Mutation of myocardial mitochondrial DNA was investigated in human left ventricles obtained at autopsy using the polymerase chain reaction (PCR). Seventeen autopsy cases were examined, including patients with diabetes mellitus, myocardial infarction, cardiomyopathy, cancer, and other diseases. Two cases of diabetes mellitus, 2 of myocardial infarction, and 1 of pulmonary fibrosis showed a 7.4 kb deletion of myocardial mitochondrial DNA. Primer shift PCR confirmed that an amplified DNA fragment had not been obtained by misannealing of the primers. It is unclear how much these findings are related to the severity or prognosis of the various diseases, but they indicate that mutation of myocardial mitochondrial DNA can occur in other diseases besides cardiomyopathy, although the influence of aging could not be excluded.

Aging↗

PubMed1993

Chymotrypsin inhibitory conformation of dipeptides constructed by side chain-side chain hydrophobic interactions.

A complete series of configurational isomers (L-L, L-D, D-L and D-D) of a dipeptide Leu-Phe benzyl ester have been synthesized and assayed for chymotrypsin. In the conformational analysis by 400 MHz 1H NMR, the L-D and D-L isomers, but not the L-L and D-D isomers, showed fairly large upfield shifts (0.2-0.4 ppm) of Leu-beta CH2 and gamma CH proton signals, indicating the presence of shielding effects from the benzene ring. In addition to distinct signal splitting of Phe-beta CH2, the NOE enhancement observed between Leu-delta CH3 and Phe-phenyl groups revealed that these groups are in close proximity. These data indicated that L-D and D-L isomers form a hydrophobic core between side chains of adjacent Leu and Phe residues. When the dipeptides were examined for inhibition of chymotrypsin using Ac-Tyr-OEt as a substrate, the L-L isomer showed no inhibition, itself becoming a substrate. However, the other three isomers inhibited chymotrypsin in a competitive manner, and the D-L isomer was strongest with Ki of 2.2 x 10(-5) M. It was found that the D-L isomer was only slowly hydrolysed but the L(or D)-D isomer was not. H-D-Phe-L-Leu-OBzl with the inverse sequence of H-D-Leu-L-Phe-OBzl inhibited chymotrypsin more strongly (Ki = 6.3 x 10(-6) M).(ABSTRACT TRUNCATED AT 250 WORDS)

Chymotrypsin↗

PubMed1993

Latent menstrual cycle in pre-menarcheal monozygotic twins.

The distribution of menarcheal interval-length between cotwins in 67 pairs of female identical twins in Tokyo was found to cluster at fairly constant intervals. When delayed in one twin, the menarche occurred in the second twin at intervals of approximately 28 days after that of the earlier twin. This finding suggests the existence of a latent lunar or menstrual cycle in pre-menarcheal girls, evidence for which was detected by recording the menarcheal intervals between MZ cotwins in days.

Adolescent↗

PubMed1993

Distribution of radioisotopic beryllium in mice after administration by various routes of injection.

A 7BeCl2 solution containing 0.5 micrograms Be per mouse was injected subcutaneously, intraperitoneally, intramuscularly, intrathoracically, and intravenously, and distribution was observed for periods up to 1 wk. 7Be was excreted more rapidly following intravenous injection than by the other routes of injection. The amount of Be found in the liver or the spleen was substantial at 1 d after intraperitoneal injection. It increased more in the spleen at 7 d after either intraperitoneal or intrathoracic injection. On the other hand, the amounts of Be stayed almost constant in the kidneys, by the various routes of injection. When injected intrathoracically, the amounts of Be in the heart and the lung were greater than when administered by the other routes of injection. The amounts of Be in the femurs of mice administered by these routes of injection, except with intravenous injection, were greater than in the other organs. The percentage of 7Be in the mineralized bone was 90% of that of 7Be in the femurs when injected intraperitoneally or intrathoracically. However, the ratio of Be in the mineralized bone to that in the bone marrow was 3 to 2. Beryllium had thus a closer affinity for the femurs than for the other organs investigated, with the different modes of administration used. The amount of Be in the entire skeleton was estimated to be substantial. Within the limitations of 1 wk of exposure, the skeleton would appear to be a critical organ. This would suggest that osteosarcomas may occur following administration of Be to laboratory animals for a long-term period.

Animals↗

PubMed1993

Protection against cucumber mosaic virus (CMV) strains O and Y and chrysanthemum mild mottle virus in transgenic tobacco plants expressing CMV-O coat protein.

Transgenic tobacco expressing the coat protein (CP) of cucumber mosaic virus strain O (CMV-O) showed a significant level of protection against CMV strains O and Y. When inoculum concentrations were increased, the transformants showed a stronger level of protection against CMV-O than against CMV-Y. The substitution of an amino acid residue between CMV-O and CMV-Y, which is presumed to change the conformation of CP, may reflect the difference in susceptibility to these viruses. Furthermore the transgenic tobacco plants showed a significant level of protection against chrysanthemum mild mottle virus, a member of the cucumovirus group but with no serological relationship to CMV.

Capsid↗

PubMed1993

[Biological characters of the clinically isolated strains of Escherichia coli O157:H7 in Canada].

Biological characters of enterohemorrhagic Escherichia coli (EHEC) strains isolated from food poisoning cases in Canada, 1987-1988 were examined in comparison with that isolated in Saitama, 1990. The Saitama strain was found to belong to biotype I, and biotypes I and II were found in Canada. Most of the strains including the Saitama strain were found to have siderophilins suggesting their advantageous growth in vivo. An enteroinvasive strain with 140 megadalton (Md) plasmid and two colicinogenic strains with 4.8 Md plasmids were detected. All strains were found to have 60 Md plasmids. This plasmid might be specific for this serotype. A few strains were resistant to streptomycin (SM) and/or tetracycline (TC), and a strain transferred its SM-TC resistances by conjugation. Many strains including the Saitama strain were found to produce vero cytotoxin (VT) types 1 and 2 (VT1 and VT2). A few type 2 and untypable toxin producing strains were also detected. VT titers produced by untypable toxin producing strains were over 10 times lower than those by other strains. High annealing temperature for PCR amplification of VT1 gene and a variety of annealing temperatures of VT2 gene suggested that the nucleotide sequences for VT1 gene were well preserved, but that those for VT2 might have some mutations.

Animals↗

PubMed1993

A transcription initiation site for the hepatitis B virus X gene is directed by the promoter-binding protein.

Recent studies have demonstrated the transacting function of the X gene product of hepatitis B virus. However, little information is available on the regulation of X gene expression. In this report, we first investigate a cellular factor regulating X gene transcription by DNA transfection, using the human hepatoma cell line HuH-7, which is permissive for HBV replication as well as X mRNA transcription. A sequence-specific cellular factor was found to bind to the promoter region upstream of the first ATG (nucleotide [nt] 1248) of the X open reading frame. DNase I footprinting analysis showed the binding sequence of this factor to be situated between nt 1097 and 1119, where an 8-bp palindrome structure resides. S1 nuclease analysis of X gene transcripts demonstrated the binding site to be adjacent to two major start sites (nt 1117 and 1125) of X mRNA. Second, we demonstrate that introduction of a mutation into the binding site gives rise to a loss of the binding with a concomitant shift of the transcription start site of X mRNA beyond the 8-bp palindrome structure, causing it to become more heterogeneous. Thus, the promoter-binding protein appears to be involved in directing the transcription initiation site of the X gene toward the downstream region of the X promoter when X protein is produced from X mRNA.

Base Sequence↗

PubMed1993

Delirium associated with Joseph disease.

Three Japanese patients with Joseph disease from different families developed sleep disturbance, followed by delirium at the middle to end stage. Brain CT scans of the three patients showed brainstem tegmental atrophy. EEG revealed slowing of background activity. Two necropsy cases showed degeneration of the reticular formation, raphe nuclei and locus ceruleus in the brainstem tegmentum in addition to the common pathological findings of Joseph disease. The clinicopathological correlation between the delirium and the brainstem tegmental atrophy in Joseph disease is discussed.

Atrophy↗

PubMed1993

[Effects of quinapril on the development of hypertension, cardiac hypertrophy and stroke in salt-sensitive Dahl rats and stroke-prone spontaneously hypertensive rats].

The effects of repeated administration of quinapril (10 mg/kg/day) on the development of hypertension, cardiac hypertrophy and survival rate were examined, and compared with those of enalapril (10 mg/kg) in salt-sensitive Dahl (Dahl S) rats and 1% saline-loaded stroke-prone spontaneously hypertensive rats (SHRSP). The Dahl S rats were treated with the drugs at 10 to 20 weeks of age and the SHRSP, at 8-19 weeks of age. (1) In the Dahl S rats, salt loading rapidly raised systolic blood pressure, which was around 220 mmHg at 10 weeks of age. Both quinapril and enalapril significantly prevented the development of hypertension (below 160 mmHg) and cardiac hypertrophy. Age-associated histopathological alterations in the kidney and mesenteric artery in Dahl S rats were suppressed by the drug treatment. (2) Salt-loaded SHRSP rapidly developed severe hypertension (270 mmHg at 12 weeks of age) accompanied with stroke signs, and 19 animals out of 20 died by the end of the experiment. Both quinapril and enalapril significantly inhibited the age-associated development of hypertension and markedly improved the survival rate (only two animals out of 16 died in both groups). These results suggest that quinapril has protective actions against age-associated development of hypertension and cardiac hypertrophy, and as a result, it prolongs the life span.

Animals↗

PubMed1993

HLA B44-restricted cytotoxic T lymphocytes recognizing an epitope on hepatitis C virus nucleocapsid protein.

Cytotoxic T lymphocytes have been reported to be involved in the immune clearance of virus-infected cells and in the pathogenesis of viral infection. We studied the cytotoxic T lymphocyte response to the putative nucleocapsid protein of hepatitis C virus in patients with chronic hepatitis C. Cytotoxic T lymphocytes specific for hepatitis C virus nucleocapsid protein were generated from peripheral blood lymphocytes by means of repeated stimulation with a synthetic hepatitis C virus nucleocapsid protein peptide. The cytotoxic T lymphocytes were CD8 positive and recognized an epitope in hepatitis C virus nucleocapsid protein residues 81 to 100 in association with a human leukocyte antigen class I molecule, B44. The peptide-induced cytotoxic T lymphocytes recognized target cells synthesizing hepatitis C virus nucleocapsid protein endogenously, though less efficiently than peptide-pulsed target cells. The human leukocyte antigen B44-restricted cytotoxic T lymphocyte response was observed in three of five patients with chronic hepatitis C and a human leukocyte antigen B44 molecule but in neither of two hepatitis C virus-negative healthy individuals with human leukocyte antigen B44 molecules. The results demonstrate the presence of hepatitis C virus-specific cytotoxic T lymphocytes in the peripheral blood of patients with chronic hepatitis C and provide a strategy to study the role of cytotoxic T lymphocytes in the viral clearance and the pathogenesis of hepatitis C virus infection.

Antigens, Viral↗

PubMed1992

Hemopoietic histocompatibility (Hh-1) phenotype and the regulation of its expression.

Hybrid resistance (HR) is primarily controlled by the genes of the Hemopoietic histocompatibility-1 (Hh-1) locus within the H-2 complex. HR is a consequence of the Hh-1-controlled target determinants in homozygous parental strain mice and their absence in heterozygous F1 hybrid mice. To examine the mechanism that controls the Hh-1 phenotype, three independent clones of somatic cell hybrids between parental lines EL-4 (C57BL/6 origin, H-2b) and R1 (C58 origin, H-2k) were studied. The line EL-4 is Hh-1b-positive and is subject to HR by H-2b heterozygous F1 mice, but R1 lacks the Hh-1b allele and is not susceptible to HR. Of the three hybrid clones, F263.2 is Hh-1b-positive, whereas the other two, F262.2 and F264.2, are Hh-1b-negative, as judged by these cells' capacity to compete in vivo with the grafted parental C57BL/6 bone marrow cells in the resistant (C57BL/6 x C3H)F1 mice. All three clones express the H-2b and H-2k class I antigens equally well, are susceptible to activated NK cells to the same extent, and all carry four copies of chromosome 17. However, Southern analysis reveals that clone F263.2 contains three copies of H-2b chromosome and one H-2k, whereas the other two clones carry two copies each of the parental chromosome 17. The results suggest that the relative copy number of specific alleles is the crucial determinant of the Hh-1 phenotype, and render unlikely both the gene dosage hypothesis and the trans-acting dominant suppression hypothesis to account for the noncodominant expression of the Hh-1 phenotype.

Animals↗

PubMed1992

Pathology of the cerebellar dentate and interpositus nuclei in Joseph disease: a morphometric investigation.

Cerebellar dentate and interpositus nuclei pathology was studied morphometrically in 3 patients with Joseph disease compared to 3 control subjects. Size of neurons, number of small neurons (cell body area: 50-199 microns 2) and large neurons (cell body area: 200 microns 2 or greater) at the rostral, medial and caudal levels, neuronal cell density, total volume of the gray bands, and total neuronal cell number were evaluated in the dentate, emboliform, and globose nuclei, using an image analyzer, after making horizontal serial 20-microns thick sections of a unilateral cerebellar hemisphere embedded in celloidin. The number of large neurons in Joseph disease was around 20% of that in the controls at each level in the individual nucleus (P less than 0.05 or P less than 0.01). In contrast, the number of small neurons was significantly reduced only at the caudal level of the dentate nucleus (P less than 0.05). The neuronal cell density was decreased within the nuclei. The total volume of the gray bands was reduced to about 70% within the nuclei (P less than 0.05 or P less than 0.01). The total number of neurons was decreased to about a third, a half, and a third within the dentate (P less than 0.001), emboliform (P less than 0.01), and globose nuclei (P less than 0.001), respectively. The principal pathologic change of the dentate and interpositus nuclei in Joseph disease was severe loss of neurons, with significant loss of the large neurons, indicating that Joseph disease is a type of cerebellar efferent system disorder.

Adult↗

PubMed1992

Identification of a binding protein to the X gene promoter region of hepatitis B virus.

The X protein of hepatitis B virus (HBV) is a transactivator to homologous and heterologous viral and cellular transcriptional regulatory elements. One sequence-specific binding protein, whose binding site located from nt 1102 to nt 1117 of HBV DNA, was identified by mobility shift assay and DNase I foot-printing analysis. A CAT assay experiment demonstrated this 16-bp binding site to have a promoter activity in the X gene transcription. The 58-bp DNA fragment (nt 1085 to nt 1142), which contains the above binding site, could be enhanced by the HBV enhancer. Mobility shift assay using the mutated 58-bp DNA fragments as probes, showed that the mutation, which damaged the palindrome structure between nt 1105 and nt 1112, resulted in loss of the binding activity. This mutation also remarkably reduced the promoter activity. The binding site differed from the target sequences of known transcriptional factors. This factor was thus concluded to be a binding protein to the X gene promoter (X-PBP) of HBV. A homology search demonstrated the binding site to be highly homologous to the promoter elements of human laminin receptor (2H5epitope) and lipoprotein receptor-related protein (LRP) genes.

Base Sequence↗

PubMed1992

The alterations of norepinephrine and acetylcholine concentrations in immature rat urinary bladder caused by streptozotocin-induced diabetes.

The concentrations of norepinephrine (NE) and acetylcholine (ACh) in the body and base of the bladder were investigated two, four and eight weeks after the administration of streptozotocin to four-week-old rats. At four and eight weeks after following dosage, NE concentrations in the base of the bladder of the diabetic rats were significantly higher than those of control rats. At the two-week diabetic condition, ACh concentrations in both the body and base of the bladder diabetic rats were about two-fold higher than in the respective control levels and remained constant for eight weeks. However, the control rats showed dramatic increase in ACh concentration from two to four weeks after dosage. There was no significant difference in the response of bladder muscle strips to phenylephrine, isoproterenol and ACh in the diabetic vs. control rats throughout the experiment. These observations suggest that the alteration of autonomic nervous system may occur at an early stage of diabetes mellitus in immature rats and that the high concentration of NE in the diabetic bladder base may reflect an adaptive overfunction of the adrenergic system probably to maintain continence. Furthermore, the lack of change in ACh concentration with age in diabetic rats may suggest an impaired development of the cholinergic system.

Acetylcholine↗