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Biomedical subjects

K Oka

Publications and source records attributed to K Oka.

At least 397 records · Page 22Linked to original sources
PubMed1990

Suppression of endogenous cortisol for evaluating pharmacodynamics of prednisolone in early allograft rejection in renal transplantation.

Concentrations of endogenous cortisol were examined in 34 kidney-transplant recipients by improved "high-performance" liquid chromatography. Ten recipients were treated with prednisolone and azathioprine, the others with prednisolone and cyclosporine. Peripheral serum samples were collected just before transplantation, daily for two weeks after the transplant, weekly until discharge for about two months, and then monthly or occasionally. Mean (+/- SD) cortisol concentrations, initially 145 +/- 87 micrograms/L, decreased immediately to 5.93 +/- 5.11 micrograms/L after transplant, remained at almost these same values for two months, and then swiftly increased to 51 +/- 59 micrograms/L by 1000 days. Cortisol concentrations within the period characterized by a cumulative dose of prednisolone at 300-700 mg were correlated significantly with the presence or absence of acute allograft rejection; patients with cortisol greater than 4 micrograms/L had a higher risk of rejection. The majority of stable patients showed cortisol concentrations between 1 and 4 micrograms/L throughout the cumulative prednisolone period characterized above. Concentrations less than 1 microgram/L after high-dose administration of methylprednisolone were accompanied by severe lung infection. We conclude that suppressed concentrations of endogenous cortisol, as assessed by highly specific HPLC, might provide a basis for predicting the therapeutic efficacy and adverse effects of prednisolone.

Adult↗
PubMed1989

Determination of the active-site serine of 6-aminohexanoate-dimer hydrolase.

Diisopropylfluorophosphate, an inhibitor of serine proteinase, was used to label 6-aminohexanoate-dimer hydrolase, a nylon oligomer degradative enzyme of Flavobacterium sp. K172. More than 95% of the enzyme activity was lost upon incorporation of 1-1.5 molecules inhibitor/subunit of the enzyme. The tryptic peptide of the labeled enzyme was purified by HPLC (reverse-phase partition) and its amino acid sequence was identified. Radioactivity was found to be incorporated into an 8-amino-acid peptide (108His-Leu-Leu-Met-Ser-Val-Ser-Lys115). Amino acid alteration from Ser to Ala at the position 112 by site-directed mutagenesis caused loss of enzyme activity to below the detection threshold (1% of the activity of the parental enzyme). These results indicate that Ser112 is essential for the activity.

Affinity Labels↗
PubMed1989

Expression of lipoprotein lipase gene in combined lipase deficiency.

The expression of the gene for lipoprotein lipase (LPL) was studied in brown adipose tissue and the liver of combined lipase deficient (cld/cld) and unaffected mice. The mRNA specific for LPL was detected in both animals. Although the size of LPL mRNA in cld mice was similar to that of unaffected mice, the mRNA concentration in affected animals was higher than in unaffected animals. We also studied the LPL gene mutation in cld mice by Southern blot analysis. No restriction fragment length polymorphisms were observed after digestion with 16 endonucleases. These data indicate that there is no gene insertion or deletion, but do not exclude the possibility of point mutation in the LPL structural gene. However, the present results agree with the hypothesis that the genetic defect in cld is not due to a mutation in the LPL structural gene, but instead involves the defective post-translational processing of LPL or defective cellular function affecting transport and secretion of this enzyme group.

Animals↗
PubMed1989

Determination of cyclosporin A in the serum of kidney transplant patients by rapid-flow fractionation and normal-phase high-performance liquid chromatography.

High-performance liquid chromatography was used to determine cyclosporin A (CsA) concentrations in the serum of kidney transplant patients by rapid-flow fractionation (RFF) followed by silica gel normal-phase high-performance liquid chromatography (HPLC). The extraction of CsA from serum was achieved by RFF using a short diatomaceous earth column eluted with diethyl ether-n-hexane (50:50, v/v). The recovery was more than 80% at concentrations of 50-150 micrograms/l. The concentration of this compound was determined by HPLC using a conventional silica gel column with 3.3 M ammonia solution-ethanol-n-hexane (0.31:10.69:89, v/v) as eluent. Concentration calibration was made on the basis of the peak-height ratio of CsA to CsD as the internal standard. The coefficient of variation of this assay was less than 6.5% and the results were used for the therapeutic drug monitoring of CsA administered to kidney transplant patients. Measurements of the CsA concentrations in 160 serum specimens were also made by conventional radioimmunoassay (RIA) using commercial kits. The data obtained by RIA were on average 2.5 times those obtained by HPLC. Higher values in RIA were observed characteristically with patients with severe disfunction resulting from CsA hepatotoxicity. From the results, it appeared that HPLC rather than RIA provides more precise and reliable values for the concentration of this drug.

Adult↗
PubMed1989

Fungus invasion of human hair tissue in tinea capitis caused by Microsporum canis: light and electron microscopic study.

Previously, we reported a morphological change of Trichophyton violaceum in hair tissue in black dot ringworm. To investigate the morphology of Microsporum canis in human hais tissue, three cases of tinea capitis by M. canis were examined by both light and electron microscopy. The fungal elements, which were located deeplyin the keratogenous zone, showed nonseptate hyphae in the outer part of the hair cortex. With the upward development of hair tissues, some hyphae invaded the keratinized inner root sheath and were there transformed into arthrospores, which then occupied the large volume of the inner root sheath; each spore was surrounded by an electron-lucent halo. In some affected hair follicles, at the follicular isthmus level, a microabscess composed of polymorphonuclear leukocytes was often formed in the outer root sheath adjacent to the arthrospores in the keratinized inner root sheath. On the other hand, the remaining hyphae in the cortex became degenerated. Fungi did not invade the hair-germinative cells. There is a distinct relationship between the morphological change of fungi and the differentiation of hair cells in tinea capitis by M. canis as well as in that by T. violaceum, although the direction of invasion and pathological roles of fungal elements within hair tissue are significantly different between the two species of fungi.

Child, Preschool↗
PubMed1989

DNA polymorphisms at the lipoprotein lipase gene: associations in normal and hypertriglyceridaemic subjects.

Lipoprotein lipase is a rate determining enzyme for the removal of triglyceride-rich lipoproteins from the blood stream. We examined whether genetic variation at the lipoprotein lipase gene locus was related to the fasting plasma level of triglycerides in both a normal and hypertriglyceridaemic population. Two restriction fragment length polymorphisms revealed by the enzymes PvuII and HindIII generated alleles designated H1, 17.5 kb;H2, 8.7 kb;P1, 7.0 kb;P2, 4.4 and 2.5 kb, respectively. These were studied in 46 Caucasian hypertriglyceridaemic subjects in comparison with 86 normolipidaemic controls. The respective allelic frequencies were H1 0.211, H2 0.789 and H1 0.414, H2 0.586 (p less than 0.01). Similar differences in allelic frequencies were found in a smaller group of Japanese hypertriglyceridaemic subjects (n = 29) compared to Japanese controls (n = 41, p less than 0.01). Ninety-three healthy Caucasians were genotyped for both polymorphic sites to relate to levels of plasma triglyceride. We found that individuals with genotype P1P1 had fasting triglyceride levels of 0.96 +/- 0.31 mmol/l (n = 20) compared to genotype P2P2 with levels of 1.31 +/- 0.66 mmol/l (n = 30, p less than 0.02); heterozygous subjects (P1P2) had intermediate levels of plasma triglyceride (1.15 +/- 0.46 mmol/l, n = 43). The HindIII alleles were not significantly associated with variation in levels of plasma triglyceride, cholesterol, or HDL-cholesterol. We conclude that DNA variations at, or around, the lipoprotein lipase gene may constitute genetic determinants for both the population variation in plasma triglyceride levels as well as for the common metabolic disorder of primary hypertriglyceridaemia.

DNA↗
PubMed1989

Effects of synthetic and naturally occurring flavonoids on mitogen-induced proliferation of human peripheral-blood lymphocytes.

Examination was made of the effects of 17 synthetic and naturally occurring flavonoids on human lymphocyte proliferation in the presence of concanavalin A as a mitogen. Twelve of the flavonoids examined were mono-hydroxy or methoxy derivatives. The mitogen-induced response of lymphocytes was evaluated from the extent of the incorporation of [3H]thymidine into cells in vitro. All the compounds showed inhibitory effects; 4.5-77.7% of [3H]thymidine incorporation was blocked by an 1.0 micrograms/ml concentration. The viability of lymphocytes before and after treatment, as assessed by a dye exclusion test, indicated no change, and thus the flavonoids may inhibit DNA synthesis. The flavonoids possessing 5-hydroxyl, 5-methoxyl and 6-methoxyl groups, and those with cyclohexyl instead of phenyl substituent (i.e. 2-cyclohexyl-benzopyran-4-one), showed the greatest inhibition. The inhibitory effect of any one of them was less than one half that of prednisolone, but essentially the same or somewhat exceeding that of bredinine or azathioprine. It would thus appear that the well-known anti-inflammatory effects of flavonoids may possibly arise in part from the inhibition of the proliferative response of lymphocytes.

Chemical Phenomena↗
PubMed1989

Effects of synthetic and naturally occurring flavonoids on Na+,K+-ATPase: aspects of the structure-activity relationship and action mechanism.

A comparative study was made of the effects of 15 synthetic and naturally occurring flavonoids on the hydrolytic activity of Na+, K+-adenosine triphosphatase (ATPase). Twelve of the flavonoids examined were mono-hydroxy or mono-methoxy derivatives. All inhibited Na+, K+-ATPase from dog kidney cortex when present at concentrations from 40-1000 microM. Flavones possessing cyclohexyl instead of the phenyl group (i.e., 2-cyclohexyl-benzopyran-4-one derivatives), were the most potent with IC50 at 257-320 microM. Structure-activity relationships were observed among the following mono-substituted flavones as: i) 2-cyclohexyl-benzopyran-4-one much greater than 2-phenyl-benzopyran-4-one; ii) 2-cyclohexyl-7-hydroxybenzopyran-4-one greater than 2-cyclohexyl-6-hydroxybenzopyran-4-one greater than 2-cyclohexyl-5-hydroxybenzopyran-4-one. Some flavonoids showing potent inhibitory activity were also examined for ouabain-displacement activity on human erythrocytes. Hardly any of the flavonoids were able to block [3H]ouabain binding to erythrocytes. These results suggest that the mechanism by which flavonoid block Na+, K+-ATPase is not related to the cardiac glycoside-specific binding site(s) of this enzyme.

Animals↗
PubMed1989

Immunohistochemical study of low affinity Fc receptor for IgE in reactive and neoplastic follicles.

The distribution of low affinity IgE Fc receptors (FceR2, FceRII) in reactive and neoplastic follicles was studied by an indirect immunoperoxidase method with monoclonal antibody specifically reacting to FceRII (H107). The tissues examined in this study included lymph nodes, extranodal tissues of divergent diseases, and follicular lymphomas. In the germinal centers (GCs) of the lymph follicles. FceRII showed a lace-like pattern irrespective of the distribution of IgE. In general, FceRII was positive only in the light zone and not in the dark zone of GCs. The distribution of FceRII was different from that of DRC1(+) FDC which were FceRII(+) and FceRII(-). FceRII was seen by immunoelectron microscopy on the cell surface of follicular dendritic cells (FDCs). IgE-positive GCs in Kimura's disease and Warthin's tumor were intensely positive for FceRII in their entire portion. In IgE-positive GCs, an increased number of FceRII-positive lymphoid GC cells was recognized by immunoelectron microscopic observation. In follicular lymphoma, there were also two types of FDC which were FceRII(+) and FceRII(-). These findings indicated that FceRII on FDCs was closely related to the IgE immune response and also was a marker for functional phase or differentiation of FDCs.

Angiolymphoid Hyperplasia with Eosinophilia↗
PubMed1989

Primary calvarial meningiomas.

Two cases of primary calvarial meningioma developing epidurally and protruding extracranially without subdural involvement are reported. The relevant literature on calvarial meningioma is reviewed.

Aged↗
PubMed1989

Human non-Hodgkin's malignant lymphomas serially transplanted in nude mice conditioned with whole-body irradiation.

Direct transplantation of non-Hodgkin's malignant lymphoma into athymic nude mice was successfully achieved after whole-body irradiation (5 Gy). Twenty-seven per cent (6/22) of transplanted lymphomas were established as nude mouse lines. The successful lines were derived solely from the patients with diffuse lymphoma who showed advanced clinical stage, high LDH value, large mass and poor prognosis. The histological, immunophenotypic and chromosomal characteristics of the nude mouse lines were compared with those of the original lymphomas, and the proliferative characteristics of the lines were examined. The transplanted lymphomas substantially retained the characteristics of the original lymphomas, and could be useful in biological, oncological and therapeutic studies of human malignant lymphoma.

Animals↗
PubMed1989

Clinical observations of mosquito bite reactions in man: a survey of the relationship between age and bite reaction.

To evaluate the mechanism of mosquito bite reaction in man, the reaction to Aedes albopictus was observed in 162 subjects ranging in age between 1 to 68 years old. Bite reactions were found to consist of both an immediate and a delayed reaction. The eruption and time course of the immediate reaction were consistent with type I hypersensitivity. The eruption and time course of the delayed reaction were consistent with cutaneous basophil hypersensitivity. Positive rates of immediate reaction increased from early childhood to adolescence and decreased with age from adulthood. The appearance and intensity of the delayed reaction decreased with age. Mosquito bite reactions in human beings exposed continuously and regularly are known to change from stage 1 to stage 5 (stage 1; no reaction, 2; delayed reaction only, 3; immediate and delayed reaction, 4; immediate reaction only, 5; no reaction). Analysis of the relationship between age and bite reaction in this study indicated that the principle held true even when the exposures were irregular or at random.

Adolescent↗
PubMed1989

Correlation of Aedes albopictus bite reaction with IgE antibody assay and lymphocyte transformation test to mosquito salivary antigens.

To investigate the mechanisms responsible for mosquito bite reaction, 120 subjects were experimentally exposed to Aedes albopictus bite and two types of immunological tests were performed. Specific IgE antibodies to salivary gland extract (SGE) antigens of female Aedes albopictus were measured by enzyme-linked immunosorbent assay (ELISA) in all subjects. Lymphocyte transformation tests (LTTs) to the same antigens were measured in 51 of the 120 subjects. The relationships between the results of ELISA and LTTs with bite reactions were statistically analysed. The amount of specific IgE antibodies correlated well with immediate bite reactions (r = 0.55) (p less than 0.01). Stimulation indices (SIs) to SGE antigens correlated with delayed bite reactions (r = 0.54) (p less than 0.01). The results suggest that type I hypersensitivity plays a role in the immediate reaction to mosquito bites and a cellular immune mechanism is responsible for the pathogenesis of delayed bite reactions.

Adolescent↗
PubMed1989

A study of mosquito salivary gland components and their effects on man.

To evaluate the mechanism of mosquito bite reaction in man, salivary gland extracts from female Aedes albopictus were prepared. When the extract of the gland was analysed by ion-exchange high performance liquid chromatography the amount of histamine in a pair of salivary glands of one mosquito was found to be below the limit of detection, an amount which is insufficient to produce an immediate reaction. Salivary gland extracts were fractionated to higher and lower molecular weight components. Intradermal injection tests with salivary gland extracts, which contained less than 100 ng of protein showed that the higher molecular weight fraction (molecular weight greater than 10,000) elicited an immediate and a delayed reaction similar to a bite reaction.

Adult↗