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Biomedical subjects

K Okuda

Publications and source records attributed to K Okuda.

At least 685 records · Page 38Linked to original sources
PubMed1988

Integrated structures of duck hepatitis B virus DNA in hepatocellular carcinoma.

The structure of integrated viral DNA in a hepatocellular carcinoma of a duck from Chi-tung county in China was analyzed. Three different clones of integrated viral DNA, lambda DHS 6-1, lambda DHS 6-2, and lambda DHE 6-2, were obtained from the neoplastic portion of the liver by molecular cloning. One of the three clones, lambda DHS 6-1, showed inverted repetition of integrated viral DNA with chromosomal flanking sequences. Another clone, lambda DHS 6-2, showed a head-to-head configuration of the core and surface gene regions of duck hepatitis B virus (DHBV) DNA. The virus-chromosome junctions were often located near direct repeat 1 or 2 of DHBV DNA in three independent clones. Nucleotide sequences at the virus-virus junctions in two clones, lambda DHS 6-1 and 6-2, indicated the possible rearrangement of chromosomal DNA and recombination of viral DNA. DHBV DNA appears to be integrated into the genome of hepatocytes in a manner similar to that of human and woodchuck hepatitis viruses. Thus, the duck system may serve as a useful animal model for the study of human hepatocarcinogenesis.

Animals↗
PubMed1988

Genetic control of delayed-type hypersensitivity to D-penicillamine antigen.

For determining the mechanism of genetic control of D-penicillamine free-base-specific delayed-type hypersensitivity (DTH) in mice, footpad swelling response was employed. Studies with various congenic and recombinant inbred strains of mice revealed that D-penicillamine free-base-specific DTH was controlled by the I-A subregion. The footpad swelling response showed a highly antigen-specific pattern, and revealed that D-penicillamine free base was not cross-reactive with D-penicillamine disulfide or L-penicillamine, but with D-penicillamine HCl. Treatment of immune lymphoid cells with monoclonal antibodies plus complement revealed that the cells responsible for DTH transfer were Lyt-1+2-, L3T4+ and Ia-T cells.

Animals↗
PubMed1988

Streptococcal adherence on various restorative materials.

The adherence of Streptococcus sanguis ATCC 10556, S. sanguis ATCC 10557, S. mutans Ingbritt, and S. mutans OMZ 176 to the surfaces of composite resins, amalgam alloys, and a Au-Ag-Pd alloy was measured. Adhesion was correlated with values for hydrophobicity and zeta-potential of the bacteria and the restorative materials. The hydrophobicity of the restoratives showed a positive correlation between the numbers of adherent S. sanguis cells, suggesting that hydrophobic interactions are important for the adherence of this bacterial species. In contrast, the numbers of adherent S. mutans cells showed a positive correlation with the zeta-potential of the restoratives, suggesting that electrostatic interactions are important in adherence of this bacterium.

Bacterial Adhesion↗
PubMed1988

Protective efficacy of active and passive immunizations against experimental infection with Bacteroides gingivalis in ligated hamsters.

The protective efficacy of immunization against Bacteroides gingivalis infection was examined in hamsters. Whole cells or extracted hemagglutinin of B. gingivalis 381 was injected with incomplete Freund adjuvant into the inguinal regions of hamsters. Two weeks after the rats received a booster injection, cotton threads were tied coronally to the gingival margins of the mandibular first molars, and then a streptomycin-resistant B. gingivalis 381R' strain was inoculated into the rats' oral cavities. The subcutaneous immunizations resulted in slight reductions in the numbers of B. gingivalis on the ligature threads compared with the sham-immunized group. Peroral administration of whole cells of B. gingivalis to hamsters elicited salivary immunoglobulin responses, but no reduction of B. gingivalis 381R' colonization was found in this group. Repeated passive immunizations with rabbit antiserum to B. gingivalis into the oral cavities of the hamsters resulted in a reduction in the number of organisms in the periodontal region.

Animals↗
PubMed1988

Relationship between cardiac function and the sympathetic nervous system during exercise in patients with essential hypertension.

The relationship between echographical cardiac function and sympathetic nerve activity during dynamic exercise was examined in patients with essential hypertension. Nine normotensives (Group N), 11 hypertensive patients without cardiac hypertrophy (Group NH) and 13 hypertensive patients with cardiac hypertrophy (Group HH) were studied during multistage exercise using a supine bicycle ergometer. The shortening fraction (SF) and the peak negative dD/dt in Group HH, being within the normal range, tended to be smaller than those in Group N at the 75-watt load. The mean value of the peak positive dD/dt (+dD/dt) in Group HH was significantly smaller than that in Group N at rest and during the 75-watt load. The percent increase of plasma norepinephrine (NE) levels (% delta NE) at the 75-watt load was significantly greater in Group HH than in Group N. Plasma NE, in some patients with cardiac hypertrophy and compromised cardiac function, markedly increased (% delta NE greater than or equal to 186) during exercise. % delta NE was directly related to the left ventricular mass index among all of the groups, but it was inversely related to the SF, -dD/dt, and to +dD/dt at the 75-watt load. We conclude that the augmented sympathetic nerve activity may contribute to preserving left ventricular systolic function during exercise within the normal range in hypertensive patients with cardiac hypertrophy.

Adult↗
PubMed1988

Effect of FK506 in experimental organ transplantation.

FK506 is the most potent immunosuppressive agent known. Its toxicity is substantial in dogs, minor in rats, and unknown in subhuman primates. In small doses that are nontoxic even in dogs, it can be used in synergistic combination with cyclosporine, steroids, and presumably in other drugs.

Animals↗
PubMed1988

Different distribution of decay-accelerating factor on hematopoietic progenitors from normal individuals and patients with paroxysmal nocturnal hemoglobinuria.

Deficiency of decay-accelerating factor (DAF) occurs in blood cells in paroxysmal nocturnal hemoglobinuria (PNH), characterized by an unusual susceptibility to hemolysis by complement activation. This study examined DAF expression on hematopoietic progenitors from normal individuals and PNH patients using a fluorescence-activated cell sorter (FACS) with monoclonal antibodies to DAF. Nonphagocytic mononuclear marrow cells expressing different density distributions of DAF were sorted into DAF-, DAF+/-, DAF+, and DAF++ fractions. The cells from each fraction were cultured in methylcellulose and assayed for CFU-E, BFU-E, CFU-GM, and CFU-Mix. The percentages of distribution of DAF-negative normal progenitors increased in the order of CFU-E, CFU-GM, BFU-E, and CFU-Mix, whereas those of DAF-positive cells inversely decreased in this order. These results indicate that DAF expression may accompany differentiation from CFU-Mix to CFU-E. On the other hand, most progenitors in PNH patients had little, if any, expression of DAF on their cell surfaces. These findings were supported by another approach using a complement-dependent cytotoxicity method with the anti-DAF monoclonal antibodies. Abnormal expression of DAF was found on the progenitors in the bone marrow as well as on mature cells circulating in the blood in PNH.

Blood Proteins↗
PubMed1988

Effects of forskolin and cilostazol on clot retraction.

We examined the effects of two inhibitors of aggregation of human platelets the, Forskolin and Cilostazol on clot retraction. Both substances suppressed clot retraction in a dose-dependent way. Both suppress platelet aggregation because of an increase in intercellular cyclic AMP, but there was no close correlations were shown between suppression rate for clot retraction and cyclic-AMP content in platelets in the clot in each substance. Furthermore, although it has been considered that actomyosin in platelets is a major contractile source for clot retraction and that failure of actin polymerization results suppression of clot retraction. As it was difficult to obtain active actin from platelets of the reagents on the polymerization. Cilostazol accelerated actin polymerization, whereas Forskolin did not. From these findings, it was considered that the effects of both substances on clot retraction could not be interpreted directly just by the increasing effect for intracellular cyclic-AMP. Clot retraction is consider to be a in vitro model of hemostasis and its contractile force is supplied from platelets (1,2,3). Experiments used prostaglandin E-1 revealed that elevation of cyclic-AMP (c-AMP) would regulate the clot retraction, and experiments used cytochalasin B demonstrated that actomyosin is responsible to the retraction (4,5). Many date demonstrate that elevation of c-AMP level suppresses platelet aggregation (6,7). c-AMP, therefore, should play a key role on platelet activation. Forskolin and Cilostazol are newly-developed reagents as a suppress for platelet functions. Pharmacological action of these substances have been interpreted to process increase effect for intracellular c-AMP of platelets(8,9). If so, both substances should show some effect on clot retraction. Under this assumption, we examined the effects.

Actins↗
PubMed1988

Effect of LHRH agonist (buserelin) on pulsatile secretion of LHRH and LH.

The LHRH agonist buserelin was administered intranasally to eight patients with endometriosis in doses of 300, 600 or 900 micrograms/day for six months. In all patients buserelin clearly suppressed ovulation. In the patients treated with 900 micrograms/day, estradiol levels declined to less than 30pg/ml, and LH release in response to LHRH testing decreased markedly after 2 months of treatment. A mild decrease in LH release was noted in the premarin test at the end of the treatment. At the end of buserelin treatment baseline levels of plasma LHRH, LHRH pulse amplitude and frequency were not lowered. However, baseline levels of plasma LH and LH pulse amplitude decreased. These results indicate that buserelin may act to decrease pituitary response to LHRH.

Adult↗
PubMed1988

[Morphometrical study on prognosis of stage I pulmonary adenocarcinoma].

The prognostic significance of morphometry in stage I pulmonary adenocarcinoma had been examined in Papanicolaou-stained bronchial brushings, using an image analyzer. The data of long-term survivors (LTS), alive for more than 5 years, and short-term survivors (STS), who had died within 5 years, were compared. LTS were found to have a smaller nuclear area, a shorter nuclear perimeter, and a smaller nucleolar area than those of the STS. The nuclear size is considered important in any histological subtypes. The variation index of the nuclear area, the nuclear circularity, and the number of nucleoli did not differ between the two groups. These results would seem to be useful in determining the prognosis and the indication type of adjuvant therapy to be used in surgical operations.

Adenocarcinoma↗