Biomedical subjects

A Ishihara

Publications and source records attributed to A Ishihara.

At least 109 records · Page 6Linked to original sources

PubMed1996

Comparison of succinate dehydrogenase activity and soma size relationships among neurons in dorsal root ganglia of rats and cats.

Compared to dorsal root ganglion (DRG) neurons at L5 in rats, DRG neurons at L7 in cat have a larger mean soma size, a bimodal rather than unimodal distribution of sizes and lower succinate dehydrogenase (SDH) activities for neurons of all sizes. In contrast to spinal motoneurons in both cats and rats, the larger DRG neurons have the higher SDH activities. The 10-20% higher SDH activity of DRG cells in rats than in cats may reflect, in part, a species difference of about 40% in metabolic rates.

Animals↗

PubMed1996

Imaging the traction stresses exerted by locomoting cells with the elastic substratum method.

The cytoskeletal activity of motile or adherent cells is frequently seen to induce detectable displacements of sufficiently compliant substrata. The physics of this phenomenon is discussed in terms of the classical theory of small-strain, plane-stress elasticity. The main results of such analysis is a transform expressing the displacement field of the elastic substrate as an integral over the traction field. The existence of this transform is used to derive a Bayesian method for converting noisy measurements of substratum displacement into "images" of the actual traction forces exerted by adherent or locomoting cells. Finally, the Monte Carlo validation of the statistical method is discussed, some new rheological studies of films are presented, and a practical application is given.

Animals↗

PubMed1996

Ionic current model of bipolar cells in the lower vertebrate retina.

We propose an ionic current model of bipolar cells based on the published experimental data. Five types of ionic currents identified in bipolar cell bodies, Ih, IKv, IA, ICa and IK(Ca) were described by a mathematical formulation similar to the Hodgkin and Huxley (Journal of Physiology, 117, 500-544, 1952) equations. The model parameters were estimated from the voltage clamp data. In simulation, we demonstrate that the present model reproduces not only the voltage clamp responses but also the current clamp responses of the bipolar cells. As a result, the model provides a better understanding of the functional role of the ionic currents in bipolar cells in generating the electrical responses.

Animals↗

PubMed1996

Influence of spaceflight on succinate dehydrogenase activity and soma size of rat ventral horn neurons.

Succinate dehydrogenase (SDH) activities and soma cross-sectional areas (CSA) of neurons in the dorsolateral region of the ventral horn at the L5 segmental level of the spinal cord in the rat were determined after 14 days of spaceflight and after 9 days of recovery on earth. The results were compared to those in age-matched ground-based control rats. Spinal cords were quick-frozen, and the SDH activity and CSA of a sample of neurons with a visible nucleus were determined using a digitizer and a computer-assisted image analysis system. An inverse relationship between CSA and SDH activity of neurons was observed in all groups of rats. No change in mean CSA or mean SDH activity or in the size distribution of neurons was observed following spaceflight or recovery. However, there was a selective decrease in the SDH activity of neurons with soma CSA between 500 and 800 microns2 in the flight rats, and this effect persisted for at least 9 days following return to 1 g. It remains to be determined whether the selected population of motoneurons or the specific motor pools affected by spaceflight may be restricted to specific muscles.

Animals↗

PubMed1996

Potent neuropeptide Y Y1 receptor antagonist, 1229U91: blockade of neuropeptide Y-induced and physiological food intake.

Neuropeptide Y (NPY) is thought to increase food intake through the action of Y1 (-like) receptors in the hypothalamus. To confirm the involvement of Y1 receptors in feeding behavior, selective and potent antagonists for Y1 receptors are required. In the present study, we showed that a peptide, 1229U91 [(Ile,Glu,Pro,Dpr,Tyr,Arg,Leu,Arg, Tyr-NH2)2 cyclic (2,4'),(2',4)-diamide], is a potent and selective antagonist for Y1 receptors. 1229U91 displaced [125I]peptide YY (PYY) binding to membranes of human neuroblastoma-derived SK-N-MC cells that predominantly express Y1 receptors with a K1 value 0.10 nM and inhibited the NPY-induced increase in intracellular calcium levels(IC50 = 0.27 nM). In contrast, the K1 values for [125I]PYY binding to Y2 receptors in membranes of human neuroblastoma-derived SK-N-BE2 cells and rat hypothalamus were 700 nM and more than 1 microM, respectively. Although [125I]PYY could not detect Y1 receptors in the rat hypothalamic membranes, [125I]1229U91 revealed binding sites with a high affinity (Kd = 18 pM), indicating the presence of Y1 receptors in the hypothalamus. Intracerebroventricular injection of 1229U91 (30 micrograms) into male Sprague-Dawley rats completely inhibited NPY (5 micrograms)-induced food intake without any other behavioral change. Furthermore, intracerebroventricular injection of 1229U91 significantly suppressed physiological feeding behavior after overnight fasting. These results indicate that Y1 receptors in the rat hypothalamus mediate NPY-induced food intake, and that physiological feeding behavior after overnight fasting may be largely regulated by NPY via Y1 receptors. 1229U91 may be useful for further elucidating the pathophysiological roles of NPY in feeding behavior.

Animals↗

PubMed1996

[The usefulness of percutaneous transhepatic cholecyst puncture (PTCCP) with ultrasoundimage control for acute cholecystitis].

Percutaneous transhepatic cholecyst puncture (PTCCP) is a unique treatment for acute cholecystitis by using of 21 gauge PTC needle with ultrasoundimage control. The procedure is as follows. A percutaneous transhepatic puncture of the gallbladder is made with ultrasonic guidance. After suction removal of the contents of the gallbladder, saline with antibiotics is injected. Finally PTC needle is removed after removal of the injected saline. We carried out PTCCP in 35 patients with acute cholecystitis, and compared its clinical effect with those of PTCCD (46 cases) or conservative treatment of antibiotics administration (38 cases). The treatment of PTCCP removed the clinical symptoms of acute cholecystitis rapidly compared with the conservative treatment and it made the hospitalization shorter compared with the treatment of PTCCD. PTCCP was also performed without any severe complications for patients with underlying diseases. The curative rate of PTCCP was the same as those of other former treatments. It was concluded that PTCCP is a safe, convenient, and useful treatment of acute cholecystitis.

Acute Disease↗

PubMed1995

An Evaluation of DNA Polymerase alpha as a Prognostic Predictor in Early Breast Cancers Smaller than 2 cm.

We examined the relationship between proliferative activity determined by DNA polymerase alpha and clinicopathologic variables in breast cancer patients, and evaluated the usefulness of DNA polymerase alpha as a prognostic predictor in 337 early breast cancers with tumors smaller than 2 cm, which had favorable outcomes. About 60% of tumors had lower proliferative activity. A significant correlationwas found between DNA polymerase alpha and ER, PgR, histological type, or the degree of infiltration into lymphatic vessels which reflect the prognosis. Cancers with higher DNA polymerase alpha activity were associated with shorter disease-free and overall survival times. In a multivariate analysis the DNA polymerase alpha was found to be an independent and significant factor in early breast cancer.

Journal Article↗

PubMed1995

Succinate dehydrogenase activity and soma size relationships among cat dorsal root ganglion neurons.

A large range in succinate dehydrogenase (SDH) activity and soma size among neurons in the dorsal root ganglion (DRG) and the dorsolateral region of the ventral horn (DLVH) at spinal cord level L7 was observed. Mean soma sizes were similar for the two populations. DLVH, but not DRG, neurons showed an inverse relationship between SDH activity and soma size. DRG neurons had a higher mean SDH activity than DLVH neurons, reflecting the observation that there was a population of DRG neurons with a higher oxidative capacity than DLVH neurons.

Animals↗

PubMed1995

Tenascin in breast cancer development--is epithelial tenascin a marker for poor prognosis?

(1) In mouse mammary gland development, immunoreactive tenascin (TN) is expressed in the dense mesenchyme surrounding the epithelial component of 14-day embryos, endbuds at puberty, and tumors. (2) Cells that produce TN are myofibroblastic and are characterized by nuclear invaginations, rough endoplasmic reticulum, and pinocytotic vesicles. These cells are not normally present in the stroma of mammary glands but present in cancer stroma, originating probably from fibroblasts differentiated under the influence of TGF-beta 1 stimulation. (3) Breast cancer cells are capable of synthesing TN under certain conditions. TN-non-producing MCF7 cells can produce TN when co-cultured with embryonic fibroblasts or with their conditioned medium. (4) Nine primary human breast cancers were examined for TN expression by in situ hybridization. TN mRNA was expressed in all nine cases in the stroma and in four cases in carcinoma cells as well. (5) Immunohistochemistry for TN was performed in human breast cancers, and it was found that the five-year survival after surgery was markedly lower in the group whose cancer cells were positive [corrected] for TN. TN expression in cancer cells appears to indicate poor prognosis.

Biomarkers, Tumor↗

PubMed1995

Effects of hypophysectomy on soleus muscle fibers and spinal motoneurons in rats.

The fiber type distribution of the soleus muscle in male and female rats was investigated 4 weeks after hypophysectomy. Oxidative enzyme activity of the soleus motoneurons in the spinal cord was also examined by enzyme histochemical assay. In male rats, the total number of fibers in the soleus muscle was not changed after hypophysectomy, but the percentage of intermediate (INT) fibers (with intermediate adenosine triphosphatase activity following alkaline preincubation, and high succinate dehydrogenase and alpha-glycerophosphate dehydrogenase activities) was increased. All types of fibers in the soleus muscle of hypophysectomized rats showed high adenosine triphosphatase activity following acid preincubation. Oxidative enzyme activity of the motoneurons innervating the soleus muscle was not changed after hypophysectomy. Similar results were obtained in female rats. It is suggested that the increased percentage of INT fibers in the rat soleus muscle after hypophysectomy is due to a lack or reduced levels of growth hormones, and that the metabolic capacities of the muscle fibers and of the innervating motoneurons are affected independently by hypophysectomy.

Animals↗

PubMed1995

Effects of hypobaric hypoxia on histochemical fibre-type composition and myosin heavy chain isoform component in the rat soleus muscle.

Histochemical fibre-type composition and myosin heavy chain isoform component in the soleus muscle were studied in normoxic rats at postnatal ages of 5, 10, 15, and 20 weeks and in rats exposed to hypobaric hypoxia (460 torr) for 5 weeks from postnatal ages of 5, 10, and 15 weeks. The increase in the percentage of type I fibres and the concomitant decrease in that of type IIa fibres in the soleus muscle of normoxic rats were observed until 15 weeks of age. On the other hand, no change in the fibre-type composition of the muscle during postnatal development was observed in hypoxic rats, irrespective of the age at which they were exposed to hypoxia. The changes in the myosin heavy chain isoform component (MHC I and MHC IIa) of the muscle during postnatal development and by hypoxia corresponded well with those in the muscle fibre-type composition. It is concluded that hypobaric hypoxia inhibits the growth-related shift of muscle fibre-types from type IIa to type I and of myosin heavy chain isoforms from MHC IIa to MHC I in the rat soleus muscle, and that there are no changes in the muscle fibre-type composition or the myosin heavy chain isoform component caused by hypoxia after the shifts in these parameters which occur during postnatal development are completed.

Aging↗

PubMed1995

Phenotypic and functional characterization of T-cell lines generated from colonoscopic biopsy specimens in patients with ulcerative colitis.

Intestinal T-cell lines were generated from lamina propria mononuclear cells isolated from colonoscopic biopsies in ulcerative colitis patients and controls. In both ulcerative colitis and controls, expanded cells were constituted largely by T-cell receptor alpha beta+, CD4+, CD45RA- (helper), and CD8+, CD11b- (cytotoxic) phenotypes. T-cell receptor V beta gene usage was not significantly changed after cell expansion and no difference was observed between ulcerative colitis and controls. Ulcerative colitis cells, especially those derived from the patients with long-standing disease, showed significantly higher levels of cytotoxicity against the target cells, including those of colonic epithelial origin, and enhanced production of tumor necrosis factor-alpha and interferon-gamma after short incubation with anti-CD3 antibody. Generation of T-cell lines from colonoscopic biopsy specimens may be useful for detailed functional characterization of locally infiltrating T cells in ulcerative colitis patients.

Adolescent↗

PubMed1995

Succinate dehydrogenase activity and soma size of motoneurons innervating different portions of the rat tibialis anterior.

The spatial distribution, soma size and oxidative enzyme activity of gamma and alpha motoneurons innervating muscle fibres in the deep (away from the surface of the muscle) and superficial (close to the surface of the muscle) portions of the tibialis anterior in normal rats were determined. The deep portion had a higher percentage of high oxidative fibres than the superficial portion of the muscle. Motoneurons were labelled by retrograde neuronal transport of fluorescent tracers: Fast Blue and Nuclear Yellow were injected into the deep portion and Nuclear Yellow into the superficial portion of the muscle. Therefore, motoneurons innervating the deep portion were identified by both a blue fluorescent cytoplasm and a golden-yellow fluorescent nucleus, while motoneurons innervating the superficial portion were identified by only a golden-yellow fluorescent nucleus. After staining for succinate dehydrogenase activity on the same section used for the identification of the motoneurons, soma size and succinate dehydrogenase activity of the motoneurons were measured. The gamma and alpha motoneurons innervating both the deep and superficial portions were located primarily at L4 and were intermingled within the same region of the dorsolateral portion of the ventral horn in the spinal cord. Mean soma size was similar for either gamma or alpha motoneurons in the two portions of the muscle. The alpha motoneurons innervating the superficial portion had a lower mean succinate dehydrogenase activity than those innervating the deep portion of the muscle. An inverse relationship between soma size and succinate dehydrogenase activity of alpha, but not gamma, motoneurons innervating both the deep and superficial portions was observed. Based on three-dimensional reconstructions within the spinal cord, there were no apparent differences in the spatial distribution of the motoneurons, either gamma or alpha, associated with the deep and superficial compartments of the muscle. The data provide evidence for an interdependence in the oxidative capacity between a motoneuron and its target muscle fibres in two subpopulations of motoneurons from the same motor pool, i.e. the same muscle.

Animals↗

PubMed1995

Breast cancer metastatic to uterine leiomyoma: a case report.

A case is reported of a 51-year-old woman who had a hysterectomy and bilateral salpingo-oophorectomy in the same year, following a radical mastoidectomy for breast cancer with metastases to the axillary lymph nodes. Histological examination showed breast cancer metastatic to uterine leiomyoma. The literature about metastasis of extragenital cancer to a leiomyoma is reviewed, and the possible mechanism involved is discussed.

Breast Neoplasms↗

PubMed1995

Influence of 12 weeks of hypobaric hypoxia on fibre type composition of the rat soleus muscle.

Explore the source record for details and available documents.

Air Pressure↗

PubMed1995

N-terminal quarter part of tetracycline transporter from pACYC184 complements K+ uptake activity in K+ uptake-deficient mutants of Escherichia coli and Vibrio alginolyticus.

In an attempt to clone a gene encoding the K+ uptake system from Vibrio alginolyticus, two plasmids, pKT2 and pKT4, were derived from pACYC184. These plasmids allowed the growth of K+ uptake-deficient mutant strains of Escherichia coli TK420 and V. alginolyticus FS181 in a low K+ medium. The pKT2 and pKT4 had an insertion about 7 and 6 kb, respectively, from the genome of V. alginolyticus. We prepared deletion plasmids from both plasmids and found that the site of genes inserted in the two was not identical and that the active locus corresponded to the structural gene encoding the N-terminal quarter part of tetA(C) gene. The N-terminal region of tetA(C) gene was ligated in another vector plasmid pHG165 to produce pHGK23. pHGK23 complemented the growth of TK420 in the low K+ medium. It contained only 62 bp from the genome of V. alginolyticus, and the open reading frame was composed of 98 amino acid residues from the N-terminal quarter part of tetA(C) and 5 amino acid residues attached by gene fusion. Using the Na+ -loaded cells of TK420, pHGK23 was found to increase the activity of K+ uptake. These results show that the N-terminal side tetA(C) gene product functions as a K+ uptake system.

Amino Acid Sequence↗

PubMed1995

Dietary high-linoleate safflower oil is not hypocholesterolemic in aged mice after a long-term feeding--comparison with lard, perilla oil and fish oil.

Aged mice (6 months of age) fed a conventional diet were shifted to diets containing 10% lard, high-linoleate safflower seed oil, high alpha-linolenate perilla seed oil or high-docosahexaenoate fish oil. A significant increase in whole body cholesterol (/g wt) was seen within 30 d after the shift (rapid response), followed by a gradual decrease in 60 to 120 d (slow response); similar changes occurred in all the dietary groups. Shortly after the shift, the serum cholesterol concentrations increased to higher levels in the lard and safflower oil groups than in the other groups, and the levels at 120 d were in the group order of safflower oil > lard > perilla oil > fish oil. Rapid and slow responses to dietary shifts were also seen in hepatic cholesterol levels (/g wt), which were higher in the lard group than in the other groups at 120 d. The arterial cholesterol contents of the fish oil group tended to be less than in the other groups at 120 d. Thus in aged mice after a relatively long-term feeding (> one tenth of the life-span), safflower oil was not hypocholesterolemic as compared with lard and other omega 3-rich oils. Long-term feeding of fish oil maintained serum cholesterol concentrations at lower levels than feeding with safflower oil or lard and without accumulating cholesterol in the aorta, liver or whole body; perilla oil was also hypocholesterolemic but to a lesser degree than fish oil.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

PubMed1995

Tenascin expression in cancer cells and stroma of human breast cancer and its prognostic significance.

Sections of formalin-fixed, paraffin-embedded tissues from 210 human breast cancers were immunohistochemically examined using the mAb against human tenascin (TN) RCB1. Immunoreactive TN was detected in the breast cancer stroma in 77 (36.7%) cases, whereas the remaining 133 (63.3%) were negative. Of the 77, 12 (5.7%) cases also showed positive staining in the carcinoma cell cytoplasm. The positive cells were often observed in the margin of the cancer nests at the site adjacent to the stroma. According to the staining pattern of TN, the breast cancer cases were classified into the three groups of cancer cell TN(+)/stromal TN(+), cancer cell(-)/stromal TN(+), and cancer cell(-)/stromal TN(-). Analysis of the relationship of these TN patterns with various clinicopathological characteristics of the tumors and the patient outcome revealed that, in comparison to the cancer cell(-)/stromal TN(-) group, the cancer cell TN(+)/stromal TN(+) group exhibited increased frequency of lymph node metastasis and exceptionally poor outcome, and the cancer cell(-)/stromal TN(+) group also showed more frequent metastasis and poorer outcome. Most of the cancer cell TN(+)/stromal TN(+) cases were c-erbB-2 positive and estrogen receptor negative. Furthermore, in situ hybridization of freshly obtained breast cancer tissues demonstrated that both cancer cells and stromal cells express TN mRNA. These results indicate that the TN in breast cancer is produced by cancer epithelial cells as well as by stromal mesenchymal cells, and that cancer cell TN might be involved in cancer spreading, resulting in unfavorable patient prognosis.

Adult↗