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Biomedical subjects

S Imai

Publications and source records attributed to S Imai.

At least 235 records · Page 13Linked to original sources
PubMed1995

Use of dextran-primed extracorporeal circuit in the canine model for venous return: with special references to the effects of two dihydropyridine-type Ca2+ channel blockers.

1. A successful canine "venous return (VR)" model is described, in which all hemodynamic parameters were stable for about an hour, by minimizing extracorporeal circuit primed with dextran (DX) so that the dilution of the blood was kept about 33%. 2. Increases in VR by norepinephrine (1 micrograms/kg) and dose-dependent decreases in VR by glyceryl trinitrate (1-30 micrograms/kg) were clearly observed. 3. While 1 microgram/kg of nifedipine produced a small, but significant decrease in VR, only a tendency for decrease was observed with higher doses which produced a definite fall in blood pressure. 4. Nisoldipine (1 microgram/kg) caused a small decrease in VR. However, higher doses that produced a large and persistent hypotension produced an increase in VR due probably to intense reflex translocation of the blood. The increase in VR was reversed with carvedilol, a beta-blocker with alpha-blocking activity.

Animals↗
PubMed1995

Immunochemical analysis and localisation of a cell wall antigen of Streptococcus rattus with a specific monoclonal antibody.

A monoclonal antibody specific to a cell wall antigen of Streptococcus rattus (S. rattus) was prepared after cell fusion of mouse myeloma cells to the spleen cells of mice immunized with whole cells of strain FA1. The monoclonal antibody reacted with a crude and purified polysaccharide antigen of S. rattus in precipitin reactions as well as in a solid phase enzyme assay (EIA). It also reacted in the EIA with whole cells of S. rattus strains, but did not react with any other species of the mutans group or of other oral and streptococcal species. Moreover, among many haptenic sugars and their derivatives tested, D-galactosamine and D-glucosamine strongly inhibited the reaction in a competitive enzyme immunoassay using the purified antigen and whole cells, indicating that the type-specific antigenic determinant of the organism has a structure similar to the amino group of the sugar molecules. Furthermore, immunoelectron microscopy revealed that the antigen epitopes formed an irregular fibrous structure over the entire surface of individual cells.

Animals↗
PubMed1995

Speech function following maxillectomy reconstructed by rectus abdominis myocutaneous flap.

Post-surgical maxillary defects have recently been reconstructed by microvascularized free flaps. However, few reports have evaluated the resulting speech function. This study compared the speech intelligibility of four maxillectomy patients who underwent reconstruction by rectus abdominis myocutaneous flaps (RAMCF) with that of four non-reconstructed patients who were treated with split-skin grafts and prostheses, to explore ways of achieving better speech function. Speech function was assessed by a Japanese language speech intelligibility test. Intelligibility scores ranged from 57.3% to 75.8% (mean, 70.4%) in the non-reconstructed group and from 66.2% to 77.2% (mean, 71.0%) in the reconstructed group. An analysis of articulatory manners and sites revealed that speech disorders resulted mainly from poor oronasal separation in the non-reconstructed group and from incorrect linguopalatal contact in the reconstructed group, especially for linguodentoalveolar and linguovelar sounds. Therefore, for higher speech function in the reconstructed group, dentoalveolar and palatal contours of the maxilla must be restored as closely as possible. This must also be done in patients whose maxillae are reconstructed by other types of microvascularized myocutaneous or cutaneous flaps that have similar postoperative palatal contours.

Adult↗
PubMed1995

Comparative effects of losartan, captopril, and enalapril on murine acute myocarditis due to encephalomyocarditis virus.

Losartan, a recently developed nonpeptide angiotensin II (AII) receptor antagonist, was orally administered for 14 days to mice with viral myocarditis, beginning 7 days after encephalomyocarditis virus inoculation. The angiotensin-converting enzyme inhibitors (ACEI) captopril and enalapril were also administered in the same manner to compare the therapeutic effects of these three drugs on the degree of myocarditis, acute heart failure, and left ventricular (LV) hypertrophy. Heart weight and the heart weight/body weight ratio were reduced by losartan (60 mg/kg/day) and captopril (7.5 mg/kg/day), but not by enalapril (1 mg/kg/day). LV wall thickness and cavity dimension were decreased in the losartan and captopril groups. Captopril reduced both myocardial necrosis and inflammation, whereas enalapril reduced myocardial necrosis but not inflammation. However, none of the studied losartan doses (1.2, 12, 60 mg/kg/day) influenced myocardial necrosis and inflammation resulting from viral infection. Thus, specific blockade of AII is beneficial in congestive heart failure (CHF) and LV hypertrophy but is not effective in viral-evoked inflammation and injury.

Acute Disease↗
PubMed1995

Immunohistochemical study on choline acetyltransferase in the spinal cord of patients with amyotrophic lateral sclerosis.

The authors developed a polyclonal antibody against a fusion protein containing 598 amino acids from a human choline acetyltransferase (ChAT) cDNA and 12 amino acids derived from an expression vector, and examined immunohistochemical reactivity for ChAT in large motor neurons (30 microns and more in somal minimal diameter) of the lumbar spinal cords of four patients with amyotrophic lateral sclerosis (ALS) and of four control cases. In controls, the number of large neurons included in the tissue with a total thickness of 100 microns ranged from 74 to 105 (average 87). About 60-90% (average 80%) of the neurons were positively stained in their perikarya with an anti-human ChAT antibody. In the cases of ALS, the number of large motor neurons was greatly reduced (25-60, average 38). About 4-13% (average 8%) were positively stained. These results indicate that not only large neurons are reduced in number, but also their positivity for ChAT is decreased in the anterior horn of ALS spinal cord.

Adult↗
PubMed1995

Endothelin-1 and its binding sites are upregulated in pressure overload cardiac hypertrophy.

The purpose of this study was to determine whether endothelin and endothelin receptors play an important role in the development of cardiac hypertrophy due to pressure overload in vivo. Cardiac hypertrophy was produced by placing a constricting clip around the suprarenal abdominal aorta of rats. Hemodynamic parameters and plasma and ventricular concentrations of endothelin-1 (ET-1) were measured in control unoperated rats, and 30 min, 2 and 6 h, and 1 and 8 days after operation in pressure overload rats and sham-operated rats. The density and dissociation constant of ET-1 binding sites were also measured in control rats and 1 and 8 days after pressure overload and sham operation. Additionally, in situ mRNA hybridization for preproendothelin-1 (preproET-1) mRNA was performed to determine which cells were responsible for increased ET-1 levels. Ventricular ET-1 levels increased markedly on day 8 of pressure overload, whereas plasma ET-1 levels increased transiently only 30 min after operation, quickly returning to control level. In addition, ventricular ET-1 levels on day 8 showed a significant positive correlation with the degree of cardiac hypertrophy. In situ mRNA hybridization revealed that cardiac myocytes expressed preproET-1 mRNA in hypertrophied hearts in vivo. In accord with the elevation of ventricular ET-1 levels, the density of ET-1 binding sites was increased significantly, without affecting their binding affinity, on day 8 of pressure overload. These data are compatible with the hypothesis that increases in locally produced ET-1 and the density of ET-1 binding sites have an important relationship with the development of cardiac hypertrophy in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Myocardial uptake of an iodinated branched fatty acid analog, assessed by SPECT, may detect metabolic derangement of the myocardium in diabetic patients with coronary heart disease.

The clinical implications of single-photon emission computed tomography using both a beta-methyl-branched fatty acid analog, 123I-15-(p-iodophenyl)-3-methyl-pentadecanoic acid (BMIPP), and thallium-201 (201Tl) were assessed in 30 patients with myocardial infarction (MI), 8 diabetics, 4 patients with impaired glucose tolerance, and 18 nondiabetic patients. Discordant decreases in BMIPP uptake, as compared with 201Tl uptake, in diabetic patients were significantly (p < 0.01) more frequent than in nondiabetic patients. The left ventricular (LV) ejection fraction in diabetics was significantly (p < 0.05) reduced and the LV diastolic dimension was significantly increased (p < 0.01), as compared with those in nondiabetic subjects. Analysis of peripheral blood showed no significant differences among the three test groups in metabolic abnormality. A discordant decrease in BMIPP uptake, as compared with Tl uptake, in cardiac tomography may indicate a metabolic derangement of the myocardium in diabetic patients with MI.

Adenosine Triphosphate↗
PubMed1995

Changes in the E/A ratio induced by handgrip-exercise are related to changes in the plasma atrial natriuretic peptide level, but not to changes in brain natriuretic peptide in mild essential hypertension.

We investigated the relationship between changes in atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) and changes in cardiac function during mild exercise in patients with mild hypertension. The handgrip test (HGT) was performed by 21 untreated, mildly hypertensive patients, mean age 45 +/- 5 years. M-mode and pulse Doppler echocardiograms were recorded before and during HGT. In 7 patients (Group A), diastolic function, which was determined by the peak early velocity and peak atrial velocity (E/A) ratio using Doppler echocardiography was attenuated during HGT (1.19 +/- 0.21 TO 1.04 +/- 0.16, p < 0.05). There was no change in diastolic function in the remaining 14 patients, left atrial diameter, cardiac index, ejection fraction, plasma renin activity, plasma norepinephrine, blood pressure, nor heart rate were different between the two groups. While ANP was increased in Group A during HGT (from 41.0 +/- 18.2 to 54.0 +/- 24.1 pg/ml, p < 0.05) it was unchanged in Group B (36.8 +/- 16.3 to 33.5 +/- 11.9 pg/ml). BNP did not change in either Group (Group A: 2.9 +/- 3.1 to 3.0 +/- 3.4 pg/ml, Group B: 2.6 +/- 1.6 to 3.6 +/- 4.8 pg/ml). The percent change in ANP during HGT did not correlate with the percent change in BNP. Thus, the impairment of cardiac functional reserve appeared to influence ANP excretion in patients with mild hypertension.

Adult↗
PubMed1995

Rumen ciliates of Tokara native goat in Kagoshima, Japan.

The composition of rumen ciliate protozoa was surveyed in 15 Tokara native goats, Capra hircus domesticus, inhibiting Kagoshima, Japan. As a result, of 11 species with 3 forms under 5 genera detected, Entodinium simplex, E. nanellum and E. rectangulatum were found in all the animals examined. The large ophryoscolecid ciliates detected were Polyplastron multivesiculatum and Metadinium affine alone, which have been regarded as the typical members of Type A composition proposed by Eadie. Since Tokara native goats have been bred isolated in a small islet for a long time, native goats that had been kept in south Japan might possess Type A fauna. Average ciliate density was 43.9 x 10(4) per 1 ml of rumen fluid. The number of species per host was 8.3 on average. Diversity index was 1.412 on average.

Animals↗
PubMed1995

Cyclic GMP as a second messenger in the cardiovascular system.

To delineate the importance of cyclic GMP (cGMP) as a second messenger for signal transduction within the cell, catalytic and regulatory features of the proteins involved in the synthesis and degradation of cGMP, i.e., guanylate cyclases and phosphodiesterases, are described. Characteristic features of cGMP-dependent protein kinases as intracellular receptors for cGMP and the contribution of this enzyme to the physiological functions of cGMP in the cardiovascular system are discussed.

Amino Acid Sequence↗
PubMed1995

Radiation-induced lymphomas in MSM, (BALB/cHeA x MSM) F1 and (BALB/cHeA x STS/A) F1 hybrid mice.

M.MOL-MSM (MSM) mice derived from Mus musculus molossinus progenitors showed extreme resistance to the induction of lymphomas following whole-body X-irradiation with four doses of 1.7 Gy. (BALB/cHeA x MSM) F1 mice between a high lymphoma strain, BALB/cHeA and the MSM showed a high incidence of radiation-induced lymphomas which was quite similar to that in BALB/cHeA mice, but the latent period was prolonged in the hybrids. Susceptibility in incidence was dominant over resistance in these crosses. Incidences of (BALB/cHeA x MSM)F1 hybrids irradiated with four doses of 2.5 Gy X-rays were 77% in females and 88% in males. F1 hybrids between BALB/cHeA and another resistant strain STS/A, (BALB/cHeA x STS/A) F1, also showed a high level of susceptibility, that is, lymphoma incidence was 64% in females and 63% in males. The mean latent period in the (BALB/cHeA x STS/A) F1 hybrids was similar to that in (BALB/cHeA x MSM) F1 hybrids. As all cases of tumors developed in F1 hybrids are informative concerning the detection of the loss of heterozygosity in the loci depending on the combination of two parental strains, the radiation-induced lymphomas obtained from (BALB/cHeA x MSM) F1 and (BALB/cHeA x STS/A) F1 hybrids could be useful for fine analysis of the genetic alterations involved in lymphomagenesis.

Animals↗
PubMed1995

Occult intrasacral meningocele with tethered cord--case report.

A 32-year-old female presented with a history of intermittent, severe lower back pain, exacerbated by pregnancy and persisting for several years. Magnetic resonance (MR) imaging showed a sacral mass as a low signal intensity area on the T1-weighted image and a high signal intensity area on the T2-weighted image, consistent with a cystic structure containing cerebrospinal fluid. A tethered cord attached to the thecal sac was also confirmed. Sacral laminectomy revealed thinned sacral vertebral laminae, but no neuronal elements existed within the cyst. The cyst was attached to the distal thecal sac by a small fistula. The thecal sac was explored, revealing a thick filum terminale, which was transected. The severe pain resolved postoperatively. This type of meningeal cyst, often called "occult intrasacral meningocele," is best diagnosed by MR imaging. Surgery to obliterate the fistulous tract is the optimum treatment. Total removal of the cyst is unnecessary, but evaluation of other associated congenial abnormalities is important.

Adult↗
PubMed1995

An opiate receptor in the neurohypophysis of laying hens.

An opiate binding component in the membrane fraction of the neurohypophysis of the laying hen showed a high affinity, limited capacity, reversible binding, and binding specificity to [3H]diprenorphine. The binding sites were of a single class. The equilibrium dissociation constant was .30 +/- .03 nM (mean +/- SEM; n = 5) in Scatchard analysis and .31 +/- .02 nM (n = 5) in kinetic analysis. The maximum binding capacity determined by Scatchard analysis was 619 +/- 34 fmol/mg protein (n = 5). The association and dissociation rate constants determined by kinetic analysis were .088 +/- .002 nM-1 min-1 (n = 5) and .027 +/- .001 min-1 (n = 5), respectively. The results suggest that the binding component is regarded as being an opiate receptor.

Animals↗
PubMed1995

PCR inhibition assay for DNA-targeted antibiotics.

DNA amplification by polymerase chain reaction (PCR) should be inhibited if the target for amplification region in the template DNA is nicked or cut. Based on this premise, we established a sensitive and differential assay using PCR to detect antibiotics that act on DNA. After template lambda DNA (10 pg) was incubated with antibiotics (10 approximately 20 ng) at 37 degrees C for 30 minutes in a 5 microliters reaction volume, a PCR assay (10 microliters reaction volume; 25 approximately 30 cycles) was performed under the conditions we modified, resulting in amplification of a 500 bp fragment of lambda DNA which was monitored by agarose gel electrophoresis. Among the several antibiotics examined, the anthracyclines, bleomycin, D-cycloserine and mitomycin C clearly inhibited the PCR amplification reaction, whereas actinomycin D and ofloxacin did not. Preincubation of template DNA in the presence of Fe++ was necessary for bleomycin and cycloserine to exhibit marked inhibition of PCR. Mitomycin C exhibited the inhibition in the presence of DTT and Cu+. By contrast, non-DNA-acting antibiotics (200 ng) such as aminoglycosides, beta-lactams, and macrolides showed no inhibition. The PCR-amplified fragment from lambda DNA was not degraded by incubation with the antibiotics (20 ng) that inhibited PCR. Furthermore, ethylacetate extracts of the cultured broths of actinomycetes proved to be suitable as samples for this PCR inhibition assay.

Actinomycetales↗
PubMed1995

Synergistic effects of tacrolimus and human interferon-alpha A/D in murine viral myocarditis.

The effects of interferon-alpha A/D (IFN) therapy in combination with various immunosuppressants were investigated in a murine model of viral myocarditis. Viral infection is an important cause of morbidity in immunocompromised hosts and transplant recipients. Human IFN therapy reduces viral replication, reducing the virus-induced myocardial destruction. Groups consisting of 25 C3H/He mice received i.p. injections of prednisolone, azathioprine, 15-deoxyspergualin, cyclosporine or tacrolimus (FK506), for 16 days beginning 2 days before inoculation with 500 plaque-forming units of encephalomyocarditis virus (EMCV). IFN, 10(4) U/g daily, was administered i.p. alone or in combination with immunosuppressants to separate groups of mice beginning on the day of viral inoculation. Animals were sacrificed at random at 4 or 10 days after inoculation with EMCV. The survival rate was significantly higher in mice treated with azathioprine, 15-deoxyspergualin, cyclosporine or FK506 in combination with IFN than in infected controls (P < .01) and was similar to the rate in the IFN monotherapy group. Survival in mice treated with prednisolone resembled that in infected controls and was significantly lower than in mice treated with IFN (P < .01). Heart weight was lower and cellular infiltration in the myocardium was reduced in mice treated with both FK506 and IFN compared with mice given IFN monotherapy. The results suggest that the effect of IFN therapy in viral myocarditis differs depending on which immunosuppressants is used. The findings suggest that the combination of FK506 and IFN may have beneficial effects in hosts with viral myocarditis by reducing cellular infiltration of heart.

Animals↗
PubMed1995

Effect of combination therapy with OK432 and recombinant human interferon-alpha A/D on atrial natriuretic peptide gene expression in mice with viral myocarditis.

The effects of combination therapy with the immunomodulators OK432 (derived from the Su strain of Streptococcus pyogenes A3; 1 unit corresponds to 0.1 mg of dried streptococci dissolved in 0.1 ml of saline) and human recombinant interferon-alpha A/D (IFN) on cardiac atrial natriuretic peptide (ANP) gene expression and myocardial hypertrophy were examined in a murine model of viral myocarditis with congestive heart failure. Therapy was started 24 h after inoculation with encephalomyocarditis virus and was continued for 14 days. The plasma ANP concentration in untreated infected mice was significantly (P < .01) increased on day 10 (115 +/- 48 pg/ml) and day 30 (43 +/- 22 pg/ml) after inoculation relative to that in uninfected controls (5 +/- 4 pg/ml), whereas plasma ANP levels in treated mice were significantly (P < .01) reduced on day 10 (14 +/- 13 pg/ml) and day 30 (11 +/- 9 pg/ml) in comparison with untreated infected mice. The atrial and ventricular ANP messenger RNA (mRNA) concentrations in untreated mice showed increases of approximately 1.4- and 29.3-fold, respectively, on day 10 and increases of 1.8- and 34-fold, respectively, on day 30 compared with the concentration in uninfected controls. Combined OK432 and IFN significantly (P < .01) reduced the increase in ANP mRNA concentration in ventricles to 6.0- and 6.7-fold on days 10 and 30, respectively. Neither OK432 nor IFN monotherapy reduced the ANP mRNA concentrations in atria and ventricles compared with those in untreated controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗