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Biomedical subjects

S Imai

Publications and source records attributed to S Imai.

At least 307 records · Page 17Linked to original sources
PubMed1993

Ischemic changes in myocardial ionic contents of the isolated perfused rat hearts as studied by NMR.

Using 31P-, 23Na- and 39K-NMR, we assessed ischemic changes in high energy phosphates and ion contents of isolated perfused rat hearts continuously and systematically. To discriminate intra- and extracellular Na+, a shift reagent (Dy(TTHA)3-) was used in 23Na-NMR study. In 39K-NMR study, the extracellular K+ signal was suppressed by inversion recovery pulse sequence in order to obtain intracellular K+ signal without using shift reagents. During the early period of ischemia, increases in intracellular Na+ and inorganic phosphate (Pi) were observed in addition to the well-documented decreases in creatine phosphate and ATP and a fall of intracellular pH, suggesting an augmented operation of Na(+)-H+ exchange triggered by a fall of the intracellular pH resulted from breakdown of ATP. At around 15 min of ischemia, a second larger increase in intracellular Na+ and a decrease in intracellular K+ were observed in association with a second increase in Pi. This was accompanied by an abrupt rise of the ventricular end-diastolic pressure. As there was a depletion of ATP at this time, the increase in intracellular Na+ and associated decrease in intracellular K+ may be explained by inhibition of the Na(+)-K+ ATPase due to the depletion of ATP. A longer observation with 31P-NMR revealed a second phosphate peak (at lower magnetic field to ordinary Pi peak) which increased its intensity as ischemic time lengthened. The pH of this 2nd peak changed in parallel with the changes in pH of the bathing solution, indicating the appearance of a compartment whose hydrogen concentration is in equilibrium with that of the external compartment. Thus, the peak could be used as an index of irreversible membrane damage of the myocardium.

Adenosine Triphosphate↗
PubMed1993

Epstein-Barr virus genomic sequences and specific antibodies in cerebrospinal fluid in children with neurologic complications of acute and reactivated EBV infections.

Four children with infectious mononucleosis (IM) and one with reactivated Epstein-Barr virus (EBV) infection had concomitant central nervous system disorders. Cerebrospinal fluid (CSF) samples from all five patients contained EBV genomic sequences and EBV-specific antibodies in the neurologic stage, but not during convalescence. Cerebrospinal fluid from two non-neurologic IM patients had neither EBV DNA nor EBV antibodies. The EBV-positive CSF of the five with neurological disorders were aseptic in culture and all negative for other human herpesvirus DNAs and antibodies: herpes simplex virus types 1 and 2, cytomegalovirus, varicella-zoster virus, and human herpesvirus 6. Epstein-Barr virus DNA and EBV antibodies were not detected in the CSF of 17 EBV-seropositive patients with mumps meningitis, rubella encephalitis, unknown febrile convulsion, or partial epilepsy. It is suggested that EBV plays a causal role in neurologic manifestations in patients with acute and reactivated EBV infections, through direct viral invasion and immunopathological reactions.

Acute Disease↗
PubMed1993

Relationship between myoglobin contents and increases in cyclic GMP produced by glyceryl trinitrate and nitric oxide in rabbit aorta, right atrium and papillary muscle.

Effects of glyceryl trinitrate (GTN) and nitric oxide (NO) on the cardiac functions and myocardial cyclic GMP (cGMP) contents were examined in comparison with those in the aorta and correlated with myoglobin (an inhibitor of soluble guanylate cyclase) contents using the preparations isolated from the reserpinized rabbit. GTN (10(-10)-10(-4) mol/l) produced a dose-dependent relaxation in the aorta. However, this compound exerted no effect on the rate of the spontaneous beat of the right atrium and the contraction of the papillary muscle. A transient and significant increase in cGMP was observed in the aorta with GTN (3 x 10(-6) mol/l). Although the increase was also observed in the right atrium, it was much smaller. No definite change was observed in papillary muscle. Increases in cGMP produced by NO (3 x 10(-6) mol/l) were larger and significant in all tissues; (AUCcGMP(GTN)/AUCcGMP(NO)) ratio was 30.1 for the aorta, 65.0 for the right atrium and 16.3% for the papillary muscle. Although higher concentrations of NO were necessary in the right atrium and papillary muscle to induce increases in cGMP, no differences were noted in the three tissues as regards the maximum accumulation of this substance. Furthermore, kinetic analysis of NO-induced increases in tissue cGMP indicated no marked difference in the production rate among the three tissues, while the rate of elimination of cGMP was lower in the aorta than in the atrium or the papillary muscle. The increases in cGMP observed in these three tissues were inversely related to the contents of myoglobin in respective tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1993

Escape from in vitro aging in SV40 large T antigen-transformed human diploid cells: a key event responsible for immortalization occurs during crisis.

A human diploid fibroblast strain MRC-5 was transfected with a replication origin-defective early region of SV40 containing the gene of large T antigen, and 48 clones of T antigen-transformed MRC-5 were isolated. Although T antigen prolonged the lifespan of MRC-5, all the transformed clones were still mortal. From two of the transformed MRC-5 clones, eight independent immortalized clones were obtained in triple experiments of immortalization. The transformed phenotypes of immortalized clones were widely varied and did not always retain those of the parental pre-immortalized clones. The immortalization occurred at the frequency of about 1-3 x 10(-7)/cell. From cell number and population doubling time of the immortalized clones, the immortalization was estimated to occur in or just before the crisis of parental mortal cells. The decreases of modal chromosome numbers and the loss of chromosomes 5 and 10 were found to be common in three independent immortalized clones examined. Thus, the escape from the cellular aging process seemed to be caused by certain genetic events including the loss of chromosomes at the end of lifespan in T antigen-transformed human diploid cells.

Aneuploidy↗
PubMed1993

Detection of Epstein-Barr virus DNA and EBV-determined nuclear antigen in angioimmunoblastic lymphadenopathy with dysproteinemia type T cell lymphoma.

Six cases of angioimmunoblastic lymphadenopathy with dysproteinemia (AILD)-like T cell lymphoma were analyzed by immunohistochemical staining, polymerase chain reaction (PCR) and Southern blot analysis. Five cases out of six showed gene rearrangements of the T cell receptor beta chain, indicating the existence of a clonal T cell proliferation. Epstein-Barr virus (EBV) DNA was detected in all six AILD type cases by PCR amplifying the sequence located in the internal repeat I, and confirmed by Southern blot hybridization, using a BamHI-W fragment as a probe. Detection of the EBV genome occurred more frequently as compared with other types of lymphoid disorders. Furthermore, EBV determined nuclear antigen (EBNA) was detected in UCHL-1 (CD45RO, pan-T cell marker) positive cells by immunostaining. These results suggest that a significant number of AILD type cases are T cell origin lymphomas and EBV infection may be relevant to the biological features of this type of lymphoma.

Adolescent↗
PubMed1993

Monoclonal antibodies to the large chondroitin sulphate proteoglycan from bovine temporomandibular joint disc.

Four hybrid cell lines producing monoclonal antibodies (designated AC2, AH12, DB10 and DD11) were derived from mice immunized with the large chondroitin sulphate proteoglycan isolated and purified from the bovine temporomandibular joint disc. The epitopes were partially characterized by enzyme-linked immunosorbent assays and staining patterns on immunoblots of intact proteoglycans and digests made with glycosidases and proteinases. All four monoclonal antibodies appeared to recognize some form of keratan sulphate although the epitopes for two (AC2 and DD11) were probably identical. One antibody (AH12) showed almost no reactivity with corneal keratan sulphate but stained a small keratan sulphate proteoglycan extracted from the disc, in addition to the large chondroitin sulphate proteoglycan. These antibodies were used for immunohistochemical staining of sections of the disc and showed that keratan sulphate associated with the large chondroitin sulphate proteoglycan was concentrated inside and away from the periphery of the structure but close to the inferior and superior surfaces, in a pattern which may reflect the adaptation of the extracellular matrix to the mechanical stresses placed on it by mastication.

Animals↗
PubMed1993

Role of visual feedback treatment for defective /s/ sounds in patients with cleft palate.

The role of visual feedback in the treatment of defective /s/ sounds in patients with cleft palate is described. Six patients with cleft palate who were similar in age, velopharyngeal function, and type of misarticulation were selected for this study. Treatment was provided using either visual feedback or no visual feedback. Visual feedback for tongue placement was provided by the Rion Electropalatograph (EPG). Visual feedback for frication was provided by a multi-function speech training aid (MFSTA). Improvement in /s/ sound production was assessed objectively using a method described previously (Michi et al., 1986). The results indicated that visual feedback for tongue placement and frication was especially useful in the treatment of defective /s/ sounds in patients with cleft palate who exhibited abnormal posterior tongue posturing during the production of dental or alveolar sounds.

Articulation Disorders↗
PubMed1993

Effects of spiraprilat, an angiotensin-converting enzyme inhibitor, on anesthetized dogs in a new model of acute left ventricular failure.

Spiraprilat, a new angiotensin-converting enzyme (ACE) inhibitor, was compared with enalaprilat for its ability to improve left ventricular (LV) function and metabolism in anesthetized open-chest dogs with a new model of acute LV failure (ALVF) induced by embolization of the left coronary artery with 50 microns plastic microspheres followed by intravenous (i.v.) infusion of methoxamine. With this procedure, LV end-diastolic pressure (LVEDP) increased from 4.2 +/- 0.7 to 12.8 +/- 1.3 mm Hg and remained at approximately 12 mm Hg throughout the experiment. Cardiac output (CO) decreased from 1.25 +/- 0.12 to 0.79 +/- 0.06 and 0.55 +/- 0.02 L/min at 30 and 90 min after methoxamine infusion, respectively. LVdP/dtmax and dP/dt/P decreased, while total peripheral resistance (TPR) increased. These hemodynamic changes indicated establishment of stable ALVF of a moderate degree. Moreover, decreases in myocardial lactate consumption and contents of creatine phosphate in the myocardium indicated the existence of moderate ischemia. The new ACE inhibitor, spiraprilat, as well as enalaprilat (30 micrograms/kg i.v.) effectively decreased mean aortic pressure (30%), LVEDP (20%), and TPR (30%) and increased stroke volume (SV) CO, and dP/dt/P. Both agents decreased myocardial oxygen consumption (20%) and caused a significant increase in myocardial creatine phosphate contents. These data indicate that the beneficial effects of both inhibitors extended not only to LV function but also to myocardial energy metabolism in ALVF.

Adenosine Triphosphate↗
PubMed1993

Markers of surface mucous cell type human gastric cancer cells: galactose oxidase-Schiff reactive mucins, monoclonal antibody SH-9 reactive mucins and cathepsin E.

Cellular differentiation of gastric cancer cells allows the classification of cell type into surface mucous cell, pyloric gland cell, intestinal absorptive cell and goblet cell types by mucin histochemistry and pepsinogen (Pg) immunohistochemistry. Surface mucous cell differentiation of gastric cancers of each histologic type has previously been detected by the galactose oxidase-Schiff (GOS) reaction although this is not always positive in all cases. Mucus granules of surface mucous cells of normal gastric mucosa show an intense reactivity for SH-9 (monoclonal antibody against CA125-bearing antigenic molecule fragments). Cathepsin E is also expressed in the cytoplasm of surface mucous cells, weakly in absorptive cells of duodenal villi and occasionally in pyloric gland cells. Expression of SH-9 reactive mucin and of cathepsin E were therefore investigated as possible additional markers to distinguish between the gastric cancer cell type in 203 primary stomach cancers. SH-9 reactive mucin was found selectively in GOS positive cancer cells of surface mucous cell type and/or cancer cells unclassified by mucin histochemistry. These latter cells were therefore classified into the surface mucous cell category. Cathepsin E was found mainly in cancer cells of the GOS positive surface mucous cell type and occasionally, in intestinal absorptive and pyloric gland cell types. Galactose oxidase-Schiff, SH-9 and cathepsin E reactive or positive cancer cells were found in 145 (71.4%), 151 (74.4%) and 144 (70.9%), respectively, of the 203 primary stomach cancers investigated.

Antibodies, Monoclonal↗
PubMed1993

Cardiac myxoma metastasized to the brain: potential role of endogenous interleukin-6.

Metastasis of a cardiac myxoma to the brain is extremely rare. We present the case of a 70-year-old man who had an atrial myxoma and two metastatic myxomas in the brain. The intracranial lesions were in fact diagnosed before the cardiac myxoma, since the patient developed hemiparesis before his cardiac symptoms occurred. Computerized tomography of the brain showed two high-density lesions, the larger of which was removed surgically. Follow-up computerized tomography revealed a progressive enlargement of the second lesion which was then resected. Histopathological examination showed all lesions to the benign myxomas. Interestingly, high concentrations of interleukin-6 were present in the patient's serum and cardiac myxoma. Interleukin-6 may possibly potentiate metastasis of cardiac myxoma.

Aged↗
PubMed1993

In vitro effects of the new calcium antagonist lacidipine.

The effects of lacidipine (LC), a new dihydropyridine calcium antagonist, were studied in comparison with those of nifedipine (NF) in isolated arteries of the dog (DG-AR) and isolated aorta (GP-AO), left and right atria (GP-LA, GP-RA) and ventricular papillary muscles (GP-PM) of the guinea pig. In DG-AR precontracted with high K+, LC and NF produced a concentration-dependent relaxation. The relaxant effect of LC was most potent in the basilar artery. The calcium antagonistic effects of LC was 8.7 and 2.1 times more potent than those of NF, in GP-AO and GP-LA, respectively. Thus, LC was about 4 times more selective towards vascular smooth muscles than NF. The negative chronotropic effects in GP-RA and the negative inotropic effect in GP-PM of NF were more pronounced than those of LC. NF was more potent in inhibiting the action potential of GP-PM than LC both in normal polarized and depolarized conditions. The effects of LC were long-lasting. These results suggest that LC is a potent, highly vascular-selective calcium antagonist with little cardiodepressant effects and as such may be suitable for the treatment of hypertension.

Animals↗
PubMed1993

Rumen ciliates of Ezo deer (Cervus nippon yesoensis) with the morphological comparison with those of cattle.

The composition of rumen ciliate protozoa was surveyed in 13 Ezo deer, Cervus nippon yesoensis, inhabiting Hokkaido, Japan. As a result, two species of the genus Entodinium, E. simplex and E. dubardi, were detected. Each Ezo deer had only a single species of protozoa, E. simplex or E. dubardi. Since E. simplex in Ezo deer had a wide variation in body size and shape, its measurements were compared with those of E. simplex, E. nanellum and E. exiguum obtained from Holstein-Friesian cattle feeding in the same area. The ciliate density ranged widely from 3.1 to 5882.4 x 10(3) with an average of 567.4 x 10(3) per 1 ml of rumen fluid.

Animals↗
PubMed1993

Compensatory adrenal growth and steroidogenesis after unilateral adrenalectomy.

To examine the effect of unilateral adrenalectomy on compensatory growth and steroidogenesis in the remaining adrenal gland, we determined the tissue concentrations of protein, DNA and corticosterone in the remaining adrenal gland and the circulating corticosterone and ACTH concentrations at 1, 3, 5, 7 and 14 days after unilateral adrenalectomy in male rats. The remaining adrenal weight and total protein content increased steadily over the 14 days after the operation, while the plasma ACTH increased transiently on the 1st day. The adrenal total DNA level was not significantly changed after unilateral adrenalectomy, whereas the protein/DNA ratio was significantly increased by the 14th day. These findings suggest that compensatory growth is not induced by an increase in ACTH and that hypertrophy may occur rather than hyperplasia in the remaining gland. The serum corticosterone levels and corticosterone concentration in the remaining gland were significantly increased by the 3rd day, when the plasma ACTH levels returned to normal. The aldosterone/corticosterone ratio in the remaining gland did not change during the experiment. These results indicate that steroidogenesis stimulating factors other than ACTH may be present and stimulate rather the early stages than the late stages of steroidogenesis under conditions of unilateral adrenalectomy.

Adrenal Glands↗
PubMed1993

Serum alpha 1-protease inhibitor levels in patients with chronic idiopathic urticaria.

A comparative study of serum alpha 1-protease inhibitor levels in patients with chronic idiopathic urticaria and control subjects revealed that the values in the patients were significantly lower than those in the controls, especially in patients over 60 years. The results suggests that some protease which can be inhibited by alpha 1-protease inhibitor may be involved in urticarial reactions in patients with chronic idiopathic urticaria.

Adult↗
PubMed1993

Studies on cell growth stimulating substances of low molecular weight. Part 2. Exfoliazone and lavanducyanin, potent growth promoting substances of rat liver cell line, RLN-8, produced by Streptomyces exfoliatus and Streptomyces aeriouvifer.

Exfoliazone and lavanducyanin isolated from Streptomyces exfoliatus BT-38 and Streptomyces aeriouvifer CL-190, respectively, showed strong growth promoting activities to liver cell RLN-8 established from normal Donryu rat. When RLN-8 cells were cultured in Eagle's minimal essential medium containing 1% fetal bovine serum, exfoliazone significantly stimulated the growth of RLN-8 cells. However, no effect was observed under serum-free conditions. Effective dose of exfoliazone was at the range of 0.004-0.1 microgram/ml. Cell proliferation was confirmed by MTT assay and by the increases of cell number and DNA synthesis. Lavanducyanin also stimulated the growth of RLN-8 cells in the same medium. It showed growth promoting activity at lower concentrations than exfoliazone and the effective dose was at the range of 0.0001-0.06 microgram/ml. Analogous compounds of exfoliazone and lavanducyanin also promoted the growth of RLN-8 cells. In addition, exfoliazone and lavanducyanin enhanced the growth of NIH 3T3 and T601 cells. These results indicate that exfoliazone, lavanducyanin and their related compounds seem to be a new type of growth promoting substances with low molecular weight produced by microorganisms, and that they can partially substitute for functions of serum. Since 12-O-tetradecanoylphorbol-13-acetate (TPA) did not show the growth promoting activities under the same conditions, the action mechanism(s) of exfoliazone and lavanducyanin are different from that of TPA.

Animals↗