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Biomedical subjects

K Okada

Publications and source records attributed to K Okada.

At least 793 records · Page 44Linked to original sources
PubMed1994

Sodium ion mediated regulation of Na/K-ATPase gene expression in vascular smooth muscle cells.

OBJECTIVE: Na/K-ATPase (Na,K pump) plays an important role in the regulation of intracellular ion composition. The purpose of this study is to determine whether Na+ regulates the levels of mRNA coding for Na/K-ATPase alpha and beta isoforms in cultured rat vascular smooth muscles cells. METHODS: Na/K-ATPase alpha and beta isoform mRNA expression was evaluated by northern blot analysis. The alpha 1 subunit content was determined by ELISA. A luciferase reporter gene assay was performed to study whether the alpha 1 promoter might contain Na+ responsive elements. RESULTS: Na/K-ATPase alpha 1 and beta 1 isoform mRNAs, but not alpha 2 and alpha 3 isoform mRNAs, were expressed in cultured rat vascular smooth muscle cells. Exposure of the cells to 10 microM veratridine, an Na+ channel activator, resulted in two- and threefold increases in alpha 1 and beta 1 mRNA accumulation, respectively, with a maximum at 60 min. The veratridine induced alpha 1 and beta 1 mRNA accumulation was still observed even in the absence of extracellular Ca2+. The increase in alpha 1 mRNA accumulation caused by 10 microM veratridine was associated with a significant increase in alpha 1 subunit protein accumulation. Transfection experiments with chimeric plasmids containing 5'-flanking sequences of alpha 1 isoform gene and luciferase reporter gene showed that 10 microM veratridine caused a threefold increase in luciferase activity. CONCLUSIONS: These results suggest that Na+ stimulates the transcription of Na/K-ATPase alpha 1 and beta 1 isoform genes in vascular smooth muscle cells. The transfection study further supports the premise that Na+ responsive elements are located within the 5'-flanking sequences of alpha 1 isoform gene.

Animals↗
PubMed1994

Characterisation of the external surfaces of Pseudomonas aeruginosa isolated from human blood and respiratory tract.

The surface structures of the cell envelopes of 16 clinical isolates of Pseudomonas aeruginosa were examined by electronmicroscopy with the new fixation technique of freeze-substitution. Two types of structures were observed among the organisms. In one group of strains, mostly isolated from blood, a dense fibrous layer c. 30 nm thick was found around the outer-membrane surface, whereas no such structure was observed in the other group of isolates, most of which were from sputum. Lipopolysaccharides extracted from the isolates with a dense fibrous layer were found by SDS-PAGE to have long O-polysaccharide chains, whereas strains without such a layer mostly had lipopolysaccharides that lacked high mol. wt. O-polysaccharide chains.

Bacteremia↗
PubMed1994

Primary cutaneous histoplasmosis in papuloerythroderma (Ofuji).

We report the first Japanese patient with primary cutaneous histoplasmosis who was infected inside Japan. He was not an immunocompromised host but his cutaneous lesions developed on preexisting papuloerythroderma (Ofuji). The long-term topical corticosteroid treatment for papuloerythroderma, which could have suppressed the local immunological defence system of the skin, might have been responsible for the histoplasma infection in the present case.

Aged↗
PubMed1994

Intravenous diadenosine tetraphosphate in dogs. Cardiovascular effects and influence on blood gases.

Diadenosine tetraphosphate (AP4A) has a considerable vasodilating effect. Its dose was adjusted to decrease mean arterial pressure (MAP) by 20%, 40%, 50%, 60%, and 80% of the pretreatment value, and the effects on hemodynamics and gas exchange were evaluated. AP4A produced a dose-dependent decrease in MAP within the range of doses which decreased blood pressure by up to 60%. Heart rate remained constant at hypotension levels of 40% or less, but decreased significantly at hypotension levels of 50% or more. Cardiac output increased significantly at hypotension levels of 40% or less. Systemic vascular resistance (SVR) showed a significant decrease at that time. No significant changes were observed in central venous pressure and pulmonary capillary wedge pressure at any level of hypotension. Arterial oxygen tension and calculated pulmonary shunt ratio showed no change. Base excess and pH were decreased significantly with a 60% or 80% fall of blood pressure. In conclusion, AP4A seems to act on the resistance vessels and cause a decrease in SVR.

Acid-Base Imbalance↗
PubMed1994

CA125-producing adenocarcinoma of the seminal vesicle.

A case of primary seminal vesicle carcinoma is reported. The tumor was a CA125-producing adenocarcinoma consisting of fine papillary-tubular, intricate branching or anastomosing glandular structures and was composed of small cuboidal, but occasionally hobnailed, cells with mostly clear, but occasionally granular, cytoplasm. Some tumor cells showed evidence of secretion of seromucinous materials into the interpapillary and cystic space. Immunohistochemically, almost half of the tumor cells expressed a positive reaction with anti-CA125, a common serological marker for ovarian epithelial carcinomas; however, no tumor cells expressed any other serological tumor markers such as carcinoembryonic antigen, alpha-fetoprotein, human chorionic gonadotropin, prostatic specific acid phosphatase, or prostatic specific antigen. The patient showed a high level of serological CA125, which fluctuated parallel with the growth, removal and recurrence of the tumor. The morphological and immunohistochemical findings suggested a close relationship between the present tumor and clear cell carcinoma of the ovary, which is thought to be of a Müllerian-Wolfian duct origin.

Adenocarcinoma↗
PubMed1994

Clinical experience of lower urinary tract reconstruction using a urethral Kock pouch.

The operative procedure used in the present series involved a nerve-sparing radical cystectomy, with anastomosis of the urethra using a pouch made of detubularized ileum. The 36 patients who underwent this operation were all male with an average age of 58. No deaths resulted from the operation. As far as late complications were concerned, malfunction of the antireflux nipple valve was noted in 1 patient and stenosis occurred between the urethra and pouch in 2. One patient was found to have multiple stones in the pouch and reservoir decompensation was recognized in 2. Thus, the late complication rate was 17%. There were no cases of total incontinence, but nocturnal incontinence appeared in 11 out of 31 (35%). A total of 20 out of 25 patients (80%) recovered their erectile function during the postoperative follow-up period and the disease-free survival rate at 5 years was 78%. Therefore, the urethral Kock pouch combined with nerve-sparing cystectomy has proved to be a useful procedure as far as the quality of life is concerned.

Adult↗
PubMed1994

Pharmacological characterization of alpha 1-adrenoceptor subtypes in the human prostate: functional and binding studies.

OBJECTIVE: To characterize the alpha 1-adrenoceptor subtypes of the human benignly enlarged prostate using functional and binding studies. MATERIALS AND METHODS: Strips of prostatic tissue taken from nine patients with benign prostatic hypertrophy who were undergoing open prostatectomy were used in the study. RESULTS: The strips isolated from five prostates produced a large contraction in response to noradrenaline and phenylephrine but not to clonidine. The contractile response induced by noradrenaline was competitively antagonized by representative alpha 1-adrenoceptor antagonists (prazosin, WB4101, 5-methylurapidil and HV723), the dissociation constants (pKB) being < 8.5. Pre-treatment with chloroethylclonidine was without effect on the contractile response to noradrenaline. In saturation experiments with five prostates, [3H]-prazosin bound to the prostate membranes with two distinct affinities (pKD = 9.95 +/- 0.07 and 8.71 +/- 0.04, Bmax = 151 +/- 8 and 138 +/- 3 fmol/mg protein, respectively). Unlabelled prazosin and WB4101 biphasically displaced the binding of 200 pM [3H]-prazosin; the resulting high and low pKI values for each of the antagonists were consistent with the two pKD values obtained for [3H]-prazosin in the saturation experiments. 5-Methylurapidil and HV723 displaced the [3H]-prazosin binding monophasically with an affinity (pKI) close to 8.5. CONCLUSIONS: These results suggest the presence of at least two distinct alpha 1-adrenoceptor subtypes (presumably an alpha 1C subtype with a high affinity for prazosin and WB4101, and a putative alpha 1L subtype with a low affinity for the antagonists) in the human prostate, in which the latter subtype may be predominantly involved in the contractile response to noradrenaline.

Adrenergic alpha-Antagonists↗
PubMed1994

Granulocyte colony-stimulating factor does not enhance phagocytosis or microbicidal activity of human mature polymorphonuclear neutrophils in vitro.

The direct effects of human granulocyte colony-stimulating factor (hG-CSF) on mature polymorphonuclear neutrophils (PMNs) in vitro were studied with regard to chemotaxis, superoxide production, and phagocytosis and microbicidal activity against the following viable microorganisms: Staphylococcus aureus, serum-resistant Pseudomonas aeruginosa, and Candida albicans. Recombinant hG-CSF (rhG-CSF) acted as a chemoattractant for human PMNs in a dose-dependent manner. The chemotactic response of PMNs to N-formyl-methionyl-leucyl-phenylalanine (FMLP) was not enhanced by rhG-CSF at any of the concentrations used. rhG-CSF did not induce the generation of superoxide by itself. However, rhG-CSF was able to prime human PMNs and to enhance O2- release stimulated by FMLP in a dose-dependent manner. rhg-CSF did not enhance phagocytosis or killing of the three species of microorganisms by normal PMNs. With PMNs obtained from patients who had hematological disorders or solid tumors, no enhancement of the microbicidal activity was observed in most cases. Microbial killing mediated by PMNs depended on the ratio of PMNs to target organisms. We concluded from these facts that the most important effect of rhG-CSF was to increase the number of the peripheral PMNs and not to enhance the functions of mature PMNs.

Blood Bactericidal Activity↗
PubMed1994

Cerebrospinal fluid concentrations of interleukin-1 beta, tumour necrosis factor-alpha, and interferon gamma in bacterial meningitis.

To investigate the role of the inflammatory cytokines, the cerebrospinal fluid concentrations of interleukin (IL)-1 beta, tumour necrosis factor-alpha (TNF-alpha), and interferon gamma (IFN-gamma) were measured in 11 children with bacterial meningitis and two with mycoplasmic meningoencephalitis and compared with those in 50 children with aseptic meningitis and 15 with non-pleocytotic cerebrospinal fluid. Concentrations of IL-1 beta and TNF-alpha were each significantly higher in the cerebrospinal fluid of patients with bacterial meningitis than in those with aseptic meningitis or those with non-pleocytotic cerebrospinal fluid. IFN-gamma was detected at low concentrations in the cerebrospinal fluid of only 2/11 of those with bacterial meningitis. On the other hand, the IFN-gamma concentration was the highest in the cerebrospinal fluid of patients with aseptic meningitis. These results suggest that the inflammatory cytokines are differently released in the intrathecal space infected with viruses or bacteria.

Adolescent↗
PubMed1994

Regulation of Na-K-ATPase gene expression by angiotensin II in vascular smooth muscle cells.

Na-K-adenosinetriphosphatase (Na-K-ATPase) activity profoundly influences vascular cell excitability, contractility, and volume regulation. We investigated the effect of angiotensin II on Na-K-ATPase gene expression in cultured rat vascular smooth muscle cells (VSMC). Na-K-ATPase alpha 1- and beta 1-isoform mRNAs, but not alpha 2- and alpha 3-isoform mRNAs, were expressed in cultured rat VSMC. Angiotensin II (1 microgram/ml) caused a threefold increase in alpha 1-mRNA accumulation and a fourfold increase in beta 1-mRNA accumulation; the peak increases for both alpha 1- and beta 1-mRNA were observed at 6 h. Angiotensin II induced alpha 1- and beta 1-mRNA expression in a dose-dependent manner. Pretreatment of VSMC with cycloheximide (20 micrograms/ml) or actinomycin D (5 micrograms/ml) completely inhibited angiotensin II-induced alpha 1-mRNA accumulation. Even after protein kinase C (PKC) activity was functionally depleted by treating VSMC with phorbol 12-myristate 13-acetate (10(-6) M) for 24 h, angiotensin II increased alpha 1-mRNA accumulation. The angiotensin II-induced increase in alpha 1-mRNA accumulation was associated with an increase in alpha 1-subunit protein accumulation. These results indicate that angiotensin II stimulates Na-K-ATPase alpha 1- and beta 1-isoform gene expression in VSMC and that the effect is mediated not via activation of PKC but needs synthesis of intermediate regulatory protein(s).

Angiotensin II↗
PubMed1994

Restoration of growth hormone secretion in prolonged food-deprived rats depends on the level of nutritional intake and dietary protein.

Prolonged food deprivation inhibits GH secretion in rats. To learn more about the nutritional regulation of GH secretion, we observed whether the recovery of GH secretion from prolonged food deprivation depends on the level of nutritional intake or a specific macronutrient in the refeed meal. Adult male Wistar rats were deprived of food for 72 h. Serial blood specimens were withdrawn via an indwelling right atrial cannula every 10 min using an automatic blood-sampling device. In the 72-hour food-deprived rats, the amplitude of the GH pulse progressively decreased but the pulse frequency did not differ compared to that of the fed control rats. When adult male rats were fed 5, 10 or 40 kcal of mixed meal consisting of carbohydrate 60%, protein 25% and fat 15% after 72 h of food deprivation, both the pulse amplitude and the pulse frequency immediately increased compared to those of the fasted control rats. Following these changes, the pulsatility of GH secretion was restored to normal, while the pulse amplitude was recovered in a meal-size-dependent manner. The GH secretory pattern no longer differed from that of the fed control rats in the rats fed 40 kcal of mixed meal. In the second study, the 72-hour food-deprived rats were fed 10 or 40 kcal of a protein meal consisting only of casein powder or 40 kcal of a protein-deficient meal consisting of carbohydrate 85% and fat 15%. The GH secretory pattern was restored to normal among the food-deprived rats fed 40 kcal of a protein meal.(ABSTRACT TRUNCATED AT 250 WORDS)

Activity Cycles↗
PubMed1994

Low density lipoprotein enhances the cellular action of arginine vasopressin in rat glomerular mesangial cells in culture.

The present study was undertaken to determine whether low density lipoprotein (LDL) modulates the cellular action of arginine vasopressin (AVP) in rat glomerular mesangial cells in culture. AVP increased cellular free calcium ([Ca2+]i) in a dose-dependent manner. When cells were preincubated for 24 h with 10 microgram/ml LDL, the 1 x 10(-7) M AVP-mobilized [Ca2+]i was 874 nM, a value significantly greater than that of 375 nM in the intact cells. AVP caused a biphasic change in cellular pH (pHi), namely, an early acidification followed by a sustained alkalinization, and the change in pHi produced by AVP was also enhanced by LDL. AVP stimulated a 2.2-fold increase in [3H]thymidine incorporation, an effect significantly greater in the presence of 10 micrograms/ml LDL. Furthermore, 1 x 10(-7) M AVP significantly activated mitogen-activated protein kinase from 14.0 to 24.5 pmol/mg protein. Such an activation was significantly enhanced by the LDL pretreatment. Both [3H]thymide incorporation and mitogen-activated protein kinase were not altered by 10 micrograms/ml LDL. [3H]AVP receptor binding was not affected by the LDL pretreatment. 1 x 10(-7) M AVP increased inositol trisphosphate production by 1.9-fold, an effect significantly greater in the presence of LDL. These results indicate that LDL enhances the cellular action of AVP and the AVP-stimulated cellular proliferation in glomerular mesangial cells. A site of action of LDL is the hydrolysis of phosphatidylinositol.

Animals↗