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Biomedical subjects

H Sakai

Publications and source records attributed to H Sakai.

At least 775 records · Page 43Linked to original sources
PubMed1992

The effect of exercise on anterior knee laxity in female basketball players.

To study the effect of physical activities on the anterior laxity of the knee joint, the anterior knee laxity of female semi-professional basketball players was measured during a typical day. The participants worked in the office in the morning, and practiced in the afternoon, which included a 60 minute warm-up, followed by a 150 minute game style practice. The laxity was measured six times in one day at different activity levels. The anterior knee laxity did not change during sedentary work in the morning, but increased significantly with game style practice. After 1 1/2 hours the increased anterior knee laxity had not recovered completely. However, after five hours it had recovered completely.

Adult↗
PubMed1992

Induction of ovarian growth and ovulation by administration of a chicken gonadotrophin preparation to Japanese quail kept under a short-day regimen.

1. Chronic administration of a glycoprotein fraction from chicken pituitary using an ALZET osmotic pump at 12.5 micrograms/h for 2 weeks induced growth of ovarian follicles to a mature size in the ovary and deposition of yolk in sexually immature 6-week-old Japanese quail females which were kept under 8L:16D short-day conditions. However, no ovulation was induced in these birds. 2. Injection of 500 micrograms of the glycoprotein into other immature short-day females was performed following the above chronic administration, 12 or 14 and 15 d after implantation of the osmotic pump. About 24 h after injection, 3 of 14 females laid one or two eggs. Ovulation was confirmed in 4 females by autopsy. A total of 5 of 14 females ovulated 6 eggs, and significant development of the oviduct and the cloacal opening were observed in all of the treated females. 3. Thus, complete ovarian function could be induced in sexually immature female Japanese quail by administration of avian gonadotrophin using a combination of an osmotic pump and an injection.

Animals↗
PubMed1992

Infection of macaque monkeys with a chimeric human and simian immunodeficiency virus.

Two macaque monkeys were inoculated with a chimeric human and simian immunodeficiency virus carrying the tat, rev, vpu and env genes of human immunodeficiency virus type 1. Infectious virus was recovered from one of the monkeys at 2 and 6 weeks post-infection. The hybrid nature of the isolated viruses was verified by Southern and Western blotting analyses. Both of the monkeys infected with the chimera elicited a humoral antibody response against the virus.

Animals↗
PubMed1992

Sequences responsible for efficient replication of simian immunodeficiency virus SIVMND in cells of the monocyte/macrophage lineage.

We determined the susceptibility of monocytic cell lines to infection with viral strains derived from two infectious clones of simian immunodeficiency virus isolated from a mandrill. One of the strains, which replicates poorly in T cell lines, was found to grow more rapidly than the other in these cells. The viral determinant for this property was genetically mapped within the env gene encoding a surface protein. Six amino acid substitutions identified appeared to be located outside of the domains corresponding to human immunodeficiency virus type 1 env functional domains such as the CD4-binding and V3 loop regions.

Animals↗
PubMed1992

A comparison between argon-dye and excimer-dye laser for photodynamic effect in transplanted mouse tumor.

Photodynamic therapy (PDT) utilizing a hematoporphyrin derivative (HpD) as a sensitizer has become a viable option for the local treatment of neoplastic disease. The argon-dye laser system is commonly used as a light source in this treatment modality. The excimer-dye laser, on the other hand, delivers high-energy red light in a pulsatile fashion. In this investigation, we treated BALB/c mice bearing mouse kidney sarcoma cell tumors with PDT using HpD at the dose of 5 mg/kg body weight as a photosensitizer and either a standard argon-dye laser or the pulsatile excimer-dye laser as the light source. At equal light energy doses (50 J/cm2), necrotic changes at depths averaging 4 mm from the tumor surface were obtained with the argon-dye laser (200 mW power output) while tumor necrosis at depths exceeding 15 mm from the tumor surface was obtained using the excimer-dye laser (6 mJ/pulse, 5 Hz). To determine the best conditions for photoirradiation with the excimer-dye laser, tumor-bearing mice were treated with different total light doses (10, 30 and 50 J/cm2), dose rates (1, 3 and 6 mJ/cm2), and frequencies (5, 15 and 50 Hz) of light exposure. Our results indicate that the optimal effects obtained with the excimer-dye laser are related to the total light dose used and the dose rate, but not to the frequency of light exposure.

Animals↗
PubMed1992

Altered production of IgE and IgA induced by IL-4 in peripheral blood mononuclear cells from patients with IgA nephropathy.

In order to elucidate the factors responsible for altered immunoglobulin production in patients with IgA nephropathy (IgAN), the in vitro effects of IL-4 and interferon-gamma (IFN-gamma) on the synthesis of IgE and IgA by peripheral blood mononuclear cells (PBMC) were studied. Spontaneous IgE and IgA synthesis by PBMC was significantly increased in patients with IgA nephropathy compared with controls. The maximum amounts of IgA and IgE synthesis by PBMC after stimulation with IL-4 were almost the same both in patients with IgAN and in controls. The enhancement rate of IL-4-induced IgE and IgA synthesis was significantly lower in IgAN than in the controls, suggesting in vivo preactivation of PBMC in IgAN patients. IFN-gamma suppressed IgA and IgE synthesis by PBMC from IgAN patients as well as controls. However, the suppressive effect on IgE synthesis was less prominent in patients with IgAN. These results suggested that altered IL-4 action might be involved in the development of IgA nephropathy.

Adolescent↗
PubMed1992

Arachidonic acid and prostaglandin E2 activate small-conductance Cl- channels in the basolateral membrane of rabbit parietal cells.

1. Cl- channels in the basolateral membrane of non-stimulated parietal cells in isolated rabbit gastric glands were studied by patch-clamp and noise analysis techniques. 2. Voltage-independent whole-cell currents were recorded from parietal cells equilibrated with Cl(-)-containing solutions. Upon reducing the Cl- concentration of the basolateral bathing solution, the current-voltage curve was rapidly shifted to the right. The reversal potential changed according to changes in the equilibrium potential for Cl-. 3. A Cl- channel blocker, 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB) inhibited whole-cell Cl- currents. The half-maximal inhibitory concentration of NPPB was 300 microM, and the inhibition was reversible (at less than or equal to 200 microM). Another Cl- channel blocker, 4-acetamido-4'-isothiocyanatostilbene-2,2'-dilsulphonic acid or diphenylamine-2-carboxylate was much less effective. 4. The power spectra of whole-cell Cl- current fluctuations contained one Lorentzian component. The single Cl- channel conductance was estimated to be 0.35 pS by the variance noise analysis, which is in agreement with the value obtained by a method of power spectrum analysis (0.29 pS). 5. The addition of arachidonic acid (10 microM) to the basolateral medium markedly increased the whole-cell Cl- current. The combined application of a cyclo-oxygenase inhibitor, indomethacin (50 microM), and a lipoxygenase inhibitor, esculetin (100 microM), increased the Cl- current, whereas the administration of a phospholipase A2 inhibitor, mepacrine (100 microM), significantly decreased the whole-cell Cl- current. 6. A sizeable increase in the whole-cell Cl- current was also induced by a metabolite of arachidonic acid, prostaglandin E2 (10 microM), but not by leukotriene B4 (5 microM) or D4 (10 microM). 7. The present study has shown that small-conductance Cl- channels are present in the basolateral membrane of rabbit parietal cells, and that the channel was functionally regulated by arachidonic acid and prostaglandin E2.

Animals↗
PubMed1992

[A case of eosinophilic meningitis due to Angiostrongylus cantonensis].

We report a case of eosinophilic meningitis caused by Angiostrongylus cantonensis. This patient, a 50-year-old male, had been eating uncooked slugs for 40 years. His chief complaints on admission were headache, fever and general fatigue. Neurological examination and CT findings were normal, but the CSF contained increased cells, most of which were eosinophilic cells. The presence of eosinophilic cells in the CSF is by itself abnormal. We therefore suspected eosinophilic meningitis and performed immunological tests. Since the gelatin particle method and immunological antigen antibody reaction were positive. We diagnosed the patient as having eosinophilic meningitis caused by Angiostrongylus cantonensis. There are only 27 reported cases of this disease in Japan, and most of them have been reported in Okinawa-Prefecture.

Angiostrongylus↗
PubMed1992

Lymphocyte adhesion can be regulated by cytoskeleton-associated, PMA-induced capping of surface receptors.

Intercellular adhesion in lymphocytes is mediated in part by the interaction of the integrin lymphocyte function-associated antigen-1 (LFA-1) with intercellular adhesion molecule-1 (ICAM-1). The B lymphoblastoid line JY expresses both LFA-1 and ICAM-1, and intercellular adhesion is enhanced by treatment with the phorbol ester phorbol 12-myristate 13-acetate (PMA), which also induced capping of LFA-1, ICAM-1, and human leukocyte antigen. Capping of LFA-1 is likely to result from protein kinase C (PKC) activation because receptor-mediated stimulation of PKC also led to capping. Additionally, adhesion mediated by PMA or lipopolysaccharide was blocked by either of two PKC inhibitors, calphostin C and staurosporine. PMA induced the apparent condensation of cytoskeletal elements that colocalized with the membrane protein cap. Cytoskeletal condensation and capping occurred in the absence of intercellular adhesion. Alteration in the distribution of cytoskeletal components and membrane redistribution of LFA-1 were inhibited by cytochalasin D, which also abolished intercellular adhesion. Taken together, these data suggest that intercellular adhesion is the result of PKC-mediated membrane redistribution of LFA-1 and ICAM-1, which is in turn associated with modification of the actin-based cytoskeleton.

Actins↗
PubMed1992

Minimum requirements for renal biopsy size for patients with IgA nephropathy.

In order to clarify the minimum requirements for renal biopsy size for a more accurate interpretation of renal biopsy information by light microscopy, we reanalyzed 92 open renal biopsy specimens in 92 patients with IgA nephropathy retrospectively. The mean number of functioning glomeruli per square millimeter in open renal biopsy specimens from 38 patients with a poor outcome was 1.2 +/- 0.4. In contrast, the mean number in 54 biopsy specimens from 54 patients with stable conditions for 10 years was 3.0 +/- 0.6. Therefore, there was a significant reduction (p less than 0.0001) in the numbers of functioning glomeruli in patients with a poor outcome. We found that the most important point in predicting the severity of tissue damage was detection not of the total numbers of glomeruli but of the density of glomeruli in given specimens in patients with IgA nephropathy. A biopsy sample of 1 mm x 7 mm in size of cortical origin is the minimum necessary to confidently interpret biopsy specimens from patients with IgA nephropathy.

Adolescent↗
PubMed1992

Increase of CD23-positive cells in peripheral blood from patients with IgA nephropathy and non-IgA proliferative glomerulonephritis.

CD23 is a surface marker of activated B cells as well as a low-affinity Fc receptor for IgE. In this study, we enumerated CD23-positive peripheral blood lymphocytes and evaluated their clinical significance in patients with IgA nephropathy (IgAN). Twenty-five patients with IgAN and 16 patients with non-IgA proliferative glomerulonephritis (PGN) were studied. Twenty-seven healthy adults served as controls. CD23-bearing cells were enumerated by flow cytometry, and serum IgE levels were measured by latex photometric immunoassay. Significant increases in the number of CD23-positive cells were observed in patients with IgAN (p less than 0.01) and PGN (p less than 0.05) compared with controls. A significant elevation of serum IgE levels was also observed in the patients with IgAN and PGN (p less than 0.05). No positive correlation between the number of CD23-positive cells and serum IgE levels was observed. We also examined the induction of surface CD23 expression on peripheral lymphocytes by interleukin (IL)-2, IL-3, IL-4, IL-5, IL-6, interferon (IFN)-gamma, IFN-alpha, phytohemagglutinin, concanavalin A, pokeweed mitogen, lipopolysaccharide and phorbol myristate acetate. IL-4 was revealed to have a significantly potent effect on the induction of cell surface CD23 compared with other stimulants. It was concluded that many patients with IgAN or PGN show high serum IgE levels and/or high CD23-positive cell counts in their peripheral blood, suggesting that hyperactivation of B cells might be involved in the development of IgAN and non-IgA PGN. It appeared that IL-4 may play a significant role in the etiology of these types of glomerulonephritis.

Adult↗
PubMed1992

SUPERMAN, a regulator of floral homeotic genes in Arabidopsis.

We describe a locus, SUPERMAN, mutations in which result in extra stamens developing at the expense of the central carpels in the Arabidopsis thaliana flower. The development of superman flowers, from initial primordium to mature flower, is described by scanning electron microscopy. The development of doubly and triply mutant strains, constructed with superman alleles and previously identified homeotic mutations that cause alterations in floral organ identity, is also described. Essentially additive phenotypes are observed in superman agamous and superman apetala2 double mutants. The epistatic relationships observed between either apetala3 or pistillata and superman alleles suggest that the SUPERMAN gene product could be a regulator of these floral homeotic genes. To test this, the expression patterns of AGAMOUS and APETALA3 were examined in superman flowers. In wild-type flowers, APETALA3 expression is restricted to the second and third whorls where it is required for the specification of petals and stamens. In contrast, in superman flowers, APETALA3 expression expands to include most of the cells that would normally constitute the fourth whorl. This ectopic APETALA3 expression is proposed to be one of the causes of the development of the extra stamens in superman flowers. The spatial pattern of AGAMOUS expression remains unaltered in superman flowers as compared to wild-type flowers. Taken together these data indicate that one of the functions of the wild-type SUPERMAN gene product is to negatively regulate APETALA3 in the fourth whorl of the flower. In addition, superman mutants exhibit a loss of determinacy of the floral meristem, an effect that appears to be mediated by the APETALA3 and PISTILLATA gene products.

Gene Expression Regulation↗
PubMed1992

Ultrastructure of detergent-resistant cytoskeletons in the noncortical domain of sea urchin eggs as revealed by the quick-freeze deep-etch technique.

The ultrastructure of detergent-resistant cytoskeletons in the noncortical cytoplasm of sea urchin eggs was studied by quick-freeze, deep-etch electron microscopy. Two different cytoskeletal organizations were identified in the detergent-treated sea urchin eggs. They were distinguished by the presence or the absence of long actin filaments and probably correspond to the cortex and the noncortical cytoplasm, respectively. The non-cortical cytoplasm was composed of a complex network (designated here as the ground network) of filaments 6 to 13 nm in diameter, that interconnected aggregates of small globular materials, yolk granules and a meshwork of uniform filaments (8-9 nm in diameter). The 6 to 13 nm filaments comprising the ground network were branched and associated with filaments of the same or other sizes, resulting in the formation of an extremely complex network. The meshwork of 8-9 nm filaments was homogeneous in composition and constitutes a novel structure which has not been previously described. The 8-9 nm filaments were connected to one another at their ends, forming a meshwork of polygons. Meshworks, ranging up to 3 microns in diameter, were distributed throughout the non-cortical cytoplasm of the egg. Similar cytoplasmic structures were also observed in fertilized eggs.

Actins↗
PubMed1992

Expression of a 66-kD heat shock protein associated with the process of cyst formation of a true slime mold, Physarum polycephalum.

Under unfavorable conditions for growth, haploid myxoamoebae of Physarum polycephalum retracted their pseudopodia and changed their cell shape into disk-like form, after which they constructed the cell walls to form microcysts. These morphological changes of haploid cells were associated with changes in intracellular distribution of actin filaments. Staining with phalloidin showed that actin filaments were almost uniformly distributed throughout the cytoplasm of the myxoamoebae. When these cells were transferred to a cyst-inducing medium, the actin structures changed into short rods or dots, after which the rods/dots disappeared in the microcysts. An incubation of the myxoamoebae in the cyst-inducing medium caused the synthesis of several proteins, among which a 66-kD protein was most prominently induced. The morphological changes and the induction of the 66-kD protein was pronounced at elevated temperatures, e.g. 40 degrees C. The 66-kD protein was not induced, however, when plasmodia of the same species were incubated at 40 degrees C. We found that the 66-kD protein was co-precipitated with polymerized actin and bound to ATP-agarose. A double staining of the disk-shaped cells with anti-66-kD protein antibody and phalloidin revealed superimposable localization of the 66-kD protein and actin filaments in the short rods or dots. Although the induction of the 66-kD protein was enhanced at high temperatures, the protein was immunologically unrelated to the common heat shock proteins, HSP70 and HSP90, those are highly conserved during evolution. These results indicate that the 66-kD protein is a novel heat shock protein which is specifically expressed during cyst formation.

Actins↗
PubMed1992

Studies on cerebral protective agents. II. Novel 4-arylpyrimidine derivatives with anti-anoxic and anti-lipid peroxidation activities. (2).

In a search for new cerebral protective agents with anti-anoxic (AA) and anti-lipid peroxidation (ALP) activities, a series of 4-arylpyrimidines, bearing an amino moiety in the C-5 position of the pyrimidine nucleus, was synthesized and tested for AA and ALP activities. Among them, 6-methyl-5-(4-methylpiperazin-1-ylcarbonyl)-4-(3-nitrophenyl )-2-phenylpyrimidin e (41, FK360) was most effective on both assays and on arachidonate-induced cerebral edema in rats. Structure-activity relationships in regard to AA activity of this series of compounds are also discussed.

Animals↗
PubMed1992

Effect of the combination of anticoagulant and thromboxane synthetase inhibitor (Y-20811) or receptor blockade (S-1452) on preventing thrombotic cyclic coronary flow reduction in dogs with coronary stenosis.

We examined the hypothesis that combined actions of anticoagulant (heparin) and Y-20811, thromboxane A2 synthetase inhibitor (TXSI), or S-1452, receptor blockade (TXRB), can provide better antithrombotic protection than TXSI or TXRB alone. In 20 of 33 dogs instrumented, placement of a critical stenosis at a focus of coronary vascular injury initiated a reproducible cyclic coronary flow reduction (CCFR). TXSI (1 mg/kg, IV) perfectly inhibited CCFR in 6 of 10 dogs (60%), and was associated with a significant decrease in 11-dehydro-TXB2 (85 +/- 8% of control; p < 0.05) and an increase in 6-keto-PGF1 alpha (155 +/- 38%; p < 0.05) in coronary sinus blood samples. In the remaining 4 dogs, additional administration of heparin (2000 IU) completely abolished CCFR. On the other hand, TXRB (1 mg/kg, IV) perfectly inhibited CCFR in 7 of 10 dogs (70%), and was accompanied by a significant increase in 6-keto-PGF1 alpha (214 +/- 65%; p < 0.05) and unchanged TXB2 level. In the remaining 3 dogs, additional administration of heparin (2000 IU) completely abolished CCFR. Thus, the combination of anticoagulant and TXSI or TXRB were more effective than TXSI or TXRB alone in abolishing thrombotic CCFR, suggesting that the combination might be effective for treating patients with impending myocardial infarction.

Animals↗
PubMed1992

Effects of Bacillus thuringiensis var. israelensis 20-kDa protein on production of the Bti 130-kDa crystal protein in Escherichia coli.

A 20-kDa protein of Bacillus thuringiensis var. israelensis (Bti) has been shown to be necessary for the efficient expression of the 27-kDa mosquitocidal protein gene in Escherichia coli. We have investigated the effects of this 20-kDa protein on the expression of two 130-kDa mosquitocidal protein genes (cryIVA, cryIVB) in E. coli by supplying the 20-kDa protein gene in trans. When a recombinant plasmid, pLH4BX, which was constructed to express cryIVA under the E. coli lac promoter on pUC19, coexisted with the 20-kDa protein gene, a striking increase in production of the fused CryIVA was detected. This was not accompanied by an increase in the amount of intracellular mRNA, suggesting that 20-kDa protein exerts a posttranscriptional effect. We conclude that the 20-kDa protein also stimulates the production of 130-kDa protein in E. coli.

Amino Acid Sequence↗