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Biomedical subjects

M Higashi

Publications and source records attributed to M Higashi.

At least 19 recordsLinked to original sources
PubMed1991

Why don't all termite species have a sterile worker caste?

No general theory explains why a sterile worker caste is not found in all species of both Hymenoptera and Isoptera (Insecta). Recent empirical finding show that, in the termites (Isoptera), feeding outside the nest correlates well with the evolution of the sterile (true) worker caste from the non-sterile (false) worker caste. Here we explain the connection between food-nest separation and true worker evolution in termites, providing a general theory on the restricted distribution of the sterile worker caste in the Isoptera. A cost-benefit model suggests that there is a critical level of nest stability above which natural selection favours true workers over false workers, irrespective of genetical relatedness. Because food-nest separation tends to increase nest stability, this theoretical result implies that the less a termite species consumes its nest as food, the more likely is its nest stability to fall above the critical level and a true worker caste will evolve.

Animals↗
PubMed1991

Influence of hepatitis B virus infection and age on mode of growth of hepatocellular carcinoma.

According to the extent of hepatic involvement of the tumor and that of portal vein invasion at the time of initial diagnosis, patients with hepatocellular carcinoma (HCC) were grouped into three or four groups. Correlations among the extent of hepatic involvement, extent of portal vein invasion, and prevalence of hepatitis B surface antigen (HBsAg) and age distribution were examined. The extent of hepatic involvement of the tumor and that of portal vein invasion were significantly greater in patients with positive HBsAg compared with findings in the negative patients (P less than 0.001). For cases of both positive and negative HBsAg, patients with a more extensive HCC were significantly younger. Results of the multivariate logistic regression analysis showed that hepatitis B antigenemia and younger age were statistically significant and independent positive predictors of extensive HCC. These results strongly suggest that hepatitis B surface antigenemia and age play an important role in the growth mode and the kinetics of HCC in Japanese patients.

Adult↗
PubMed1990

[The pharmacokinetics of pranoprofen in humans].

The pharmacokinetics of pranoprofen, 2-(5H-[1]benzopyrano[2,3-b]pyridin-7-yl) propionic acid (I) in humans were examined. 1-O-Acylglucuronide of I (II) and its isomer (III) were isolated from the human urine after oral administration of I. The stability of II was tested in order to establish the suitable conditions for the storage and handling of biological samples. Maximum stability of II was found at pH 3-4. Unchanged drugs, II and III were detected in the human plasma after oral administration of I. Plasma concentrations of these compounds reached the maximum at 1-2 h after the administration and thereafter decreased biphasically. From the urinary sample, 1-O-acylglucoside of I (IV) was detected in addition to unchanged drugs, II and III. Within 24 h after dosing, 1.3, 84.0, 7.0 and 0.6% of the dose were excreted as I, II, III and IV, respectively and the total urinary excretion amounted to 92.9% in term of unchanged drug.

Administration, Oral↗
PubMed1990

[A case of the Hallermann-Streiff syndrome].

The Hallermann-Streiff Syndrome has been characterized and established according to 7 positive and 5 negative signs, which were described by François. We encountered an 11 year, 5 months old boy who had 7 positive symptoms of this syndrome in our clinic. In this study, we reported on this typical patient focusing on his dental view. 1) Prolonged retention of the primary teeth which involved microdontia were noted. Congenitally missing teeth were also seen. 2) The occlusal relationship indicated open bite, and also the mandibular function was impaired. 3) The measurements of the length and width of the dental arch were smaller than that of a normal subject, and the dental arch of the maxilla was V-shaped. 4) According to X-ray cephalometric analysis, (a) the dental calculus and the alveolar bone absorption were very evident. (b) abnormal morphologic of the glenoid fossa, mandibulars condyle and the neck of mandibula were seen. These conditions were very evident on the left side. 5) The growth obstade of the maxilla and mandibla and the left shift of the mandible were found. 6) According to histological study, enamel hypoplasia was noted.

Child↗
PubMed1990

[Experimental studies of retinal glial cell proliferation on retinal surface].

Our previous reports described the formation processes of epiretinal membranes composed of retinal glial cells in the experimental vitreous hemorrhage. This report presents the pathological changes of retinal glial cells, inner limiting membranes and vitreous body in the early stage of experimental vitreous hemorrhage. Using an operating microscope, 0.3 ml of autologous whole blood was injected through the pars plana into the vitreous cavity of albino rabbits. The eyes were enucleated at 3, 7, 10, 14 and 28 days after injection. Three days after injection, normal vitreous structure disappeared and vitreous fibers condensed. Seven days after injection, red blood cells were found on the retinal surface. The inner limiting membrane, composed of lamina rara and lamina densa, had a normal appearance. Where the red blood cell were present on the retinal surface, the lamina rara of the inner limiting membrane became thin. Fourteen days after injection, where glial cells showed upheaval, lamina rara disappeared and lamina densa became thin. Afterward, glial cells extruded their cytoplasmic processes onto the retinal surface. Twenty-eight days after injection, the inner limiting membranes were normal in appearance except for the area of glial cells penetrating the inner limiting membranes. The results suggested that, in vitreous hemorrhage, glial cell proliferation onto the retinal surface is an active reaction in order to engulf the debris of the red blood cells.

Animals↗
PubMed1989

HTLV-1 rex and HIV-1 rev act through similar mechanisms to relieve suppression of unspliced RNA expression.

Human retroviruses, human T cell leukemia viruses (HTLV) and human immunodeficiency viruses (HIV), express two classes of mRNAs; fully spliced mRNA in the early phase and intron-containing mRNA in a later phase. The expressions of HTLV-1 rex and HIV rev by early mRNAs are essential for the later phase of expression of intron-containing gag and env mRNAs. Each two cis-acting sequences seem to be involved in these regulations: HTLV-1 rex depends on a splice donor (SD) and a responsible element (RXE) at the 3' end, whereas HIV rev depends on a specific repressive sequence (CRS) and a responsible element (RRE) in the intron, but does not require an SD. For analyses of these cis-acting sequences, we inserted an HIV element RRE into an HTLV-1 construct and tested the responses to HTLV-1 rex and HIV rev regulations. The results indicated that both rex and rev could regulate RNA expression of these chimeric constructs responding to an HIV RRE. A repressive element (CRS) was dispensable, and the intronic or exonic location of RRE was not important. These observations suggest that rex and rev could be functionally equivalent to induce cytoplasmic expression of unspliced RNA which expression is suppressed either by an SD or CRS depending on the construction.

Cell Line↗
PubMed1988

Anisakiasis confirmed by radiography of the large intestine.

As yet, there has been no report of acute anisakiasis of the large intestine diagnosed by radiographic demonstration of the larvae. We present such a case, in which roentgenologic examination revealed Anisakis larvae in the ascending colon.

Adult↗
PubMed1985

[Mechanism of systolic anterior motion of the mitral valve in dogs].

The mechanism of systolic anterior motion (SAM) of the mitral valve remains somewhat controversial. We previously reported that SAM can be produced in dogs using dobutamine infusion. In the present study, dobutamine infusion, dextran infusion and venesection were performed in 13 anesthetized closed-chest dogs to study the mechanism of SAM. The degree of SAM was determined by M-mode echocardiography. End-systolic and end-diastolic short-axis areas of the left ventricle at the level of the chordae tendineae and the fractional area changes were measured by two-dimensional echocardiography. SAM was produced in six of the 13 dogs during dobutamine infusions (Group 1), but not in the other seven dogs (Group 2). During dobutamine infusions, % fractional area changes were greater in Group 1 (85 +/- 5; mean +/- standard deviation) than in Group 2 (65 +/- 15) (p less than 0.01), and the end-systolic short-axis area of the left ventricle was smaller in Group 1 (0.7 +/- 0.4 cm2) than in Group 2 (1.9 +/- 0.3 cm2) (p less than 0.01), although no significant change was observed between Groups 1 and 2 in the end-diastolic short-axis area of the left ventricle. Subsequent injections of dextran (mean 340 ml) in Group 1, decreased the degree of SAM and increased the end-diastolic and end-systolic short-axis areas of the left ventricle. Subsequently, venesections (mean 400 ml) in Group 1 resulted in increases in the degrees of SAM and decreases in the end-diastolic and end-systolic short-axis areas of the left ventricle.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Isoelectric heterogeneity of human uterine estrogen binding proteins.

Upon Isoelectric Focusing (IEF) of premenopausal uterine myometrial cytosol, specific binding of estradiol (E2) can be shown at elution pH's (EpH) of 4.0-4.4, 5.0-5.2, 5.8-6.2 and 7.5-8.0. Pre-adsorption of premenopausal uterine cytosol by Concanavalin A Sepharose (Con-A) or precipitation with 30% ammonium sulfate results in loss of estradiol binding at EpH's 4.4 and 5.0. The estradiol binding sites that bind to Con-A are present in plasma and have been shown to be Sex Hormone Binding Globulin (EpH = 5.0) and Estrogen Binding Protein (EpH = 4.4). After Con-A adsorption premenopausal cytosol preincubated with 2 nM 3HE2 reveals a single peak on IEF at EpH's congruent to 6.0, while preincubation with 40 nM 3HE2 reveals specific binding peaks at EpH's of congruent to 6.0 and 7.5-8.0. Postmenopausal uterine cytosol preincubated with either 2 or 40 nM 3H-E2 on IEF reveals EpH = 5.8-6.0 binding only. Post-labeling of IEF fractions with 20 nM 3HE2 demonstrates one peak at EpH 5.8-6.0 in postmenopausal tissue and two peaks (5.8-6.2 and 7.5-8.0) in premenopausal tissue. Scatchard analysis of postmenopausal cytosol demonstrates a single population of binding sites with a dissociation constant (Kd) of 10(-10) M. Premenopausal cytosol on Scatchard analysis contains two estradiol binding populations with Kd's of 10(-10) and 10(-9) M. The data suggest that the 10(-10) M E2 binding population has a EpH of 5.8-6.2, while the 10(-9) M component has an EpH of 7.5-8.0.

Cytosol↗
PubMed1983

Arrest of 3T3 cells in G1 phase by low density lipoprotein.

Low density lipoprotein (LDL) and high density lipoprotein (HDL) were purified from normal human serum by KBr density gradient centrifugation and gel filtration through Sepharose 4B. LDL reversibly inhibited proliferation of Swiss/3T3 cells, whereas HDL had no inhibitory effect on cell growth. The LDL-induced inhibition was LDL-dose dependent and was reversed by the addition of mevalonate, a product of the reaction of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase (mevalonate: NADP+ oxidoreductase (CoA-acylating), EC 1.1.1.34). These data suggest that a specific reduction in the activity of HMG-CoA reductase produced by the addition of LDL is the main cause of the inhibition of cell proliferation. Studies of the effect of LDL on the cell cycle showed that it inhibited the entry of cells arrested in G0/G1 into the S phase but that it did not affect the transition of cells at the G1/S boundary into the M phase. The cell cycle of 3T3 is arrested solely in G1 by LDL.

Cells, Cultured↗
PubMed1979

Relative performance test of hollow fiber dialyzers.

While a number of different hollow fiber dialyzers are on the market today, the present author studied three of the cellulosic membrane dialyzers, SD-1, CF-1500 and K-102, as to their dialysance, solutes removal rate, UFR and blood residue characteristics. In order to compare these characteristics due to the difference of the membrane and the structural geometry of the dialyzers, the test results were analysed by means of analyses of variance.

Adult↗