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Biomedical subjects

H Nakamoto

Publications and source records attributed to H Nakamoto.

At least 91 records · Page 5Linked to original sources

Further simplification of ultrasensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) for anti-HTLV-I IgG using microplates and fluororeader.

In a previously reported ultrasensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) for anti-HTLV-I IgG, polystyrene beads were handled with tweezers, and bound beta-D-galactosidase activity was measured with a fluorometer. The use of tweezers was causative of false-positivity by carryover, and testing many samples was difficult. Recently, these drawbacks have been minimized using microplates and a fluororeader. However, tweezers were still required in the initial and final steps. In the present study, the immune complex, comprising 2,4-dinitrophenyl-antigen, anti-HTLV-I IgG, and antigen-beta-D-galactosidase conjugate, was formed in and trapped onto microplate wells coated with (anti-2,4-dinitrophenyl group) IgG. Subsequently, the microplate wells were incubated with epsilon N-2,4-dinitrophenyl-L-lysine and polystyrene beads, modified by attaching to plates through cylindrical bars and coated with (antihuman IgG gamma-chain) IgG, to transfer the immune complex from the microplate wells to the modified polystyrene beads. Alternatively, modified polystyrene beads coated with (anti-2,4-dinitrophenyl group) IgG and microplate wells coated with (antihuman IgG gamma-chain) IgG were substituted for microplate wells coated with (anti-2,4-dinitrophenyl group) IgG and modified polystyrene beads coated with (antihuman IgG gamma-chain) IgG, respectively. The fluorescence intensity for bound beta-D-galactosidase activity was quickly measured with a fluororeader. Thus the modified polystyrene beads were transferred from wells to wells more quickly and easily without tweezers, eliminating false-positivity due to carryover, and it became easy to test many samples with high sensitivity and reliability, although the assay of bound beta-D-galactosidase activity became slightly more time-consuming.

Animals↗

Status of patients who underwent uninephrectomy in adulthood more than 20 years ago.

We investigated the status of patients without systemic diseases who had undergone uninephrectomy for unilateral renal diseases in adulthood more than 20 years ago at Tokyo Denryoku Hospital. There were 21 participants (mean age +/- SD, 58.6 +/- 8.0 years) who fulfilled these criteria. The average interval since nephrectomy was 27.9 +/- 6.2 years. The mean current creatinine clearance was 88.5 +/- 21.2 mL/min/1.73 m2, which is 92.9% of that in healthy age- and sex-matched controls with two kidneys. The 24-hour urine protein excretion in these patients was only slightly higher than in the controls (214 +/- 190 mg v 119 +/- 62 mg, P = NS). Age at nephrectomy, length of time with a single kidney, or sex had little effect on the remnant renal functions. There was a positive correlation between current mean arterial pressure and serum creatinine (r = 0.44, P < 0.05). Patients who developed hypertension after uninephrectomy had a family history of hypertension more frequently than those with normotension (86% v 29%, P < 0.05). We conclude that (1) renal function after compensatory hyperfiltration of more than 20 years due to uninephrectomy for unilateral renal diseases in adulthood is well maintained, although hypertension has a considerable effect on the renal functions, and that (2) family history of hypertension plays a key role in determining the incidence of hypertension even in the uninephrectomized patients.

Adult↗

Prevalence of senile dementia in Okinawa, Japan. COSEPO Group. Study Group of Epidemiology for Psychiatry in Okinawa.

METHODS. The prevalence of dementia was investigated in Okinawa Prefecture, Japan. In all, 3524 subjects, > or = 65 years old, were sampled randomly (urban and rural populations 61.1% and 38.9% respectively). Phase 1 of the survey was carried out by specially trained students of the Faculty of Medicine who used the Mini-Mental State (MMS) scale (interview rate: 94.3%) to screen 522 (15.8%) of the 3312 subjects for the phase 2 survey. Phase 2, conducted by psychiatrists using the Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R) criteria, detected 172 cases of dementia. RESULTS. The estimated prevalence of dementia was 6.7%. For women, the rate increased sharply in the 90-99 year old group, and was 41.4%; for men in the 90-99 year old group prevalence was 21.2%. The ratio of Alzheimer-type dementia to multi-infarct dementia was 1.5:1 (men 1.2:1, women 1.7:1). The breakdown of the severity of dementia in the total cases was: mild 16.9%, moderate 30.8%, and severe 52.3%. The number of severe cases increased with age.

Age Distribution↗

Flow cytometric analysis of nuclear DNA content in the endoscopic biopsy tissues of gastric cancer.

The nuclear DNA content was measured by flow cytometry in gastric cancer patients using endoscopically biopsied tissue specimens. When the specimens were classified into diploid and aneuploid according to the DNA histogram, 56% (65/117) of the specimens were aneuploid, and advanced cancer was clearly more often aneuploid than early cancer. The frequency of aneuploidy appeared to be higher as the histologic depth of cancer was greater. Noncancerous tissues of the stomach were mostly diploid. The nuclear DNA ploidy pattern in gastric cancer cells could be analyzed by using endoscopic biopsy samples and this flow cytometric investigation would be possibly contributive to further characterization of gastric cancer in the diagnostic procedure of malignancy.

Adult↗

Central nervous system mediates an antihypertensive property in glucocorticoid hypertension in dogs.

OBJECTIVE: To determine whether the central nervous system has a pressor or a depressor role in glucocorticoid-induced hypertension. METHODS: Intracerebroventricular dexamethasone or its receptor antagonist, RU 38486, was administered in 20 trained conscious dogs. In addition, intracerebroventricular RU 38486 was administered in dogs treated with oral dexamethasone. RESULTS: Intracerebroventricular dexamethasone induced a dose-related reduction in blood pressure accompanied by decreased heart rate and cardiac output. In contrast, intracerebroventricular RU 38486 caused a slight but not significant elevation in blood pressure. Total peripheral resistance showed no significant change throughout the treatment with dexamethasone or RU 38486. In contrast, oral dexamethasone caused significant elevation of blood pressure associated with increased total peripheral resistance and reduced heart rate. In hypertensive dogs treated with oral dexamethasone, intracerebroventricular RU 38486 elicited a more severe form of hypertension accompanied by an attenuation of the heart rate and a reduction in cardiac output. Intracerebroventricular dexamethasone induced a significant reduction in plasma levels of adrenocorticotrophic hormone, cortisol, arginine vasopressin and noradrenaline. In addition, simultaneous central administration of RU 38486 with intracerebroventricular dexamethasone blocked the reduction in blood pressure and heart rate completely. CONCLUSION: The present data strongly suggest that endogenous glucocorticoid in the central nervous system may not have a role in the regulation of systemic haemodynamics and hormones under resting conditions, but does play an important part during the glucocorticoid excess state, for example glucocorticoid hypertension caused by oral treatment with dexamethasone. The glucocorticoid in the central nervous system opposed the elevation of blood pressure in glucocorticoid-induced hypertension by attenuating the reduction in heart rate and cardiac output via direct stimulation of glucocorticoid receptors in the brain.

Animals↗

Automated measurement of reticulated platelets in estimating thrombopoiesis.

We described a fully automated measurement of reticulated platelets using a fluorescent dye, auramine O, and a reticulocyte counter, the R-3000, equipped with special software. Reproducibility and linearity were shown to be good. In the normal subjects studied (n = 60), the mean value for reticulated platelets was 0.98% +/- 0.41% and the mean absolute count was 2.12 +/- 0.69 x 10(9)/l. The absolute count for reticulated platelets was significantly lower (p < 0.05) in patients with reduced thrombopoiesis as seen in acute myeloblastic leukemia, aplastic anemia or chemotherapy-induced thrombocytopenia and it was elevated (p < 0.05) in essential thrombocythemia and in chronic myelocytic leukemia with thrombocytosis. All 20 patients with chronic idiopathic thrombocytopenic purpura had a high percentage of reticulated platelets. The percentage of reticulated platelets was significantly increased (p < 0.05) in patients with impaired thrombopoiesis despite the reduction in the absolute count. In 2 leukemic patients, an apparent rise was noticed in the percentage of reticulated platelets which preceded by several days a progressive increase in the platelet count at the recovery phase of thrombocytopenia. The results suggest that an automated measurement of reticulated platelets can be applied to routine laboratories for clinical use.

Adolescent↗

Angiotensin-(1-7) and nitric oxide interaction in renovascular hypertension.

New studies suggest that vasodilator systems may play an important role in restraining the rise in peripheral vascular resistance associated with the evolution of arterial hypertension. We characterized in conscious dogs the hemodynamic and hormonal effects of 4 weeks of feeding either the nitric oxide synthase inhibitor N omega-nitro-L-arginine (3 mg.kg-1.d-1) or the nitric oxide precursor L-arginine (0.3 mg.kg-1.d-1) during the evolution of two-kidney, one clip hypertension. Inhibition of nitric oxide production elicited a form of hypertension more severe than that produced in placebo-fed two-kidney, one clip dogs. The higher levels of blood pressure were accompanied by lower levels of plasma renin activity and lower angiotensin II concentrations. During the chronic phase of renovascular hypertension, the fall in blood pressure produced by acute systemic injections of lisinopril or losartan was significantly reduced in dogs given the nitric oxide inhibitor. In contrast, chronic administration of L-arginine had no effect on the magnitude of hypertension or on the increases in renin activity and hyperangiotensinemia associated with the evolution of renal hypertension. Likewise, the fall in blood pressure produced by pharmacological blockade of angiotensin II was not different from that recorded in untreated renal hypertensive dogs. The vasodilator component of the blood pressure response due to intravenous injections of angiotensin-(1-7) (1 to 100 nmol/kg) was augmented in both untreated and L-arginine-treated two-kidney, one clip hypertensive dogs, but was significantly attenuated in hypertensive dogs fed the nitric oxide synthase inhibitor.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Oxidoreductases↗

Targeted inactivation of the gene psaI encoding a subunit of photosystem I of the cyanobacterium Synechocystis sp. PCC 6803.

The psaI gene encoding the 4 kDa polypeptide subunit (PsaI) of the photosystem I was cloned from the Synechocystis sp. PCC 6803, a readily transformable cyanobacterium. The gene is located immediately downstream of the psaL gene in this cyanobacterial genome and encodes a polypeptide of 40 amino acid residues with a deduced molecular mass of 4,413 Da. The deduced amino acid sequence is homologous to PsaI from other cyanobacterial and higher plants. The poly-peptide has an internal hydrophobic region with a hydrophilic C-terminal region. The gene is present as a single copy in the genome. While some of its transcripts are expressed as polycistronic mRNAs which are co-transcribed with psaL, the other may be expressed as monocistronic mRNAs. Stable mutant strains in which the gene psaI was interrupted by a gene conferring resistance to kanamycin, were generated by targeted mutagenesis. One of the mutants was characterized in detail. SDS polyacrylamide gel electrophoresis revealed that the mutant strain contained other polypeptides of photosystem I in thylakoid membranes. Growth and photosynthetic characteristics of the mutant strain under photoautotrophic conditions were similar to those of the wild type, suggesting a dispensable unknown role of PsaI for photosynthesis in Synechocystis sp. PCC 6803.

Amino Acid Sequence↗

Estrogen augments the contribution of nitric oxide to blood pressure regulation in transgenic hypertensive rats expressing the mouse Ren-2 gene.

Transgenic rats carrying the mouse Ren-2 gene (Ren-2d)27 provide a unique model to study the interplay between the renin-angiotensin system and estrogen in the pathogenesis of hypertension. In this study we measured the effects of ovariectomy and estrogen replacement on blood pressure and the contribution of vascular endothelium relaxing factor, nitric oxide, in female transgenic hypertensive rats and normotensive Sprague-Dawley (SD) rats. Both groups of animals were either ovariectomized or sham-operated at 12 weeks of age. Ovariectomized rats were treated with either 17 beta-estradiol (70 micrograms/day) or placebo for 4 weeks, whereas sham-operated rats received placebo alone. Mean arterial blood pressure measured in conscious rats directly by an arterial catheter was significantly higher in ovariectomized rats, compared with ovariectomized rats given estrogen replacement therapy for both transgenic (167 +/- 5 v 154 +/- 4 mm Hg, P < .05) and SD rats (125 +/- 4 v 113 +/- 5 mm Hg, P < .05). The contribution of endothelium-derived nitric oxide to the maintenance of blood pressure was examined by acute systemic injection of NG-monomethyl-L-arginine (L-NMMA, 10 mg/kg). L-NMMA caused a significantly greater increase in blood pressure in sham-operated transgenic as compared to SD rats (34 +/- 3 v 14 +/- 3 mm Hg, P < .05). The response in ovariectomized transgenic rats was markedly reduced (13 +/- 3 mm Hg), reaching levels that were no different from sham-operated SD rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Correlation between event-related potentials and MR measurements in chronic alcoholic patients.

Event-related potentials were recorded in 25 abstinent alcoholics, and 25 gender- and age-matched controls during a two-tone discrimination (odd ball) task. All the subjects were free from medication and dextral. MR images were examined in the alcoholics. The amplitudes of N100, N200 and P300 in the alcoholics were reduced compared with those of the controls. In order to identify morphological changes responsible for ERP abnormalities, linear regression analyses were performed between ERP measures and MRI parameters. The amplitude of N100 was inversely correlated with ventricular size. The amplitudes of P300 were inversely correlated with both ventricular size and width of cortical sulci. It was suggested that the N100 abnormality was related to subcortical structure, and P300 alteration was related to both subcortical and cortical structures in the alcoholics.

Adult↗

Effects of oral AVP receptor antagonists OPC-21268 and OPC-31260 on congestive heart failure in conscious dogs.

Rapid right ventricular pacing could induce congestive heart failure in conscious dogs with significant increase in plasma concentration of arginine vasopressin (AVP) (from 1.2 +/- 0.2 to 3.4 +/- 0.6 pg/ml). In this experimental model of heart failure, oral administration of the selective AVP V1 receptor antagonist OPC-21268 significantly increased cardiac output and improved renal function without significant changes in serum electrolytes and hormones. Oral administration of the selective AVP V2 receptor antagonist OPC-31260 induced marked water diuresis, which resulted in significant increases in serum sodium concentration, plasma renin activity, and plasma concentration of AVP, although it did not produce hemodynamic improvement. Combined administration of OPC-21268 and OPC-31260 showed supra-additive hemodynamic responses as well as additive renal and metabolic responses, i.e., it showed prolonged decrease in mean arterial pressure and profound increase in cardiac output. These results suggest that AVP plays a significant role in elevation of vascular tone through V1 receptors and plays a major role in retaining free water through V2 receptors in this model of heart failure. Furthermore, combined administration of V1 and V2 receptor antagonists could induce not only metabolic and hormonal responses but also more beneficial hemodynamic responses than those observed following treatment with V1 receptor antagonist alone.

Animals↗

Targeted inactivation of the gene psaL encoding a subunit of photosystem I of the cyanobacterium Synechocystis sp. PCC 6803.

Photosystem I is a multisubunit pigment-protein complex that functions as a light-driven plastocyanin-ferredoxin oxidoreductase in thylakoid membranes of cyanobacteria and higher plants. A 16-kDa protein subunit of photosystem I complex was isolated from the cyanobacterium Synechocystis sp. PCC 6803. The sequence of its NH2-terminal residues was determined and a corresponding oligonucleotide probe was used to isolate the gene encoding this subunit. The gene, designated as psaL, codes for a protein of 16,605 Da. The deduced amino acid sequence is homologous to the subunit PsaL of barley photosystem I. There are two conserved hydrophobic regions in the subunit PsaL that may cross or interact with thylakoid membranes. The gene psaL exists as a single copy in the genome and is expressed as a monocistronic RNA. Stable mutant strains in which the gene psaL was interrupted by a gene conferring resistance to chloramphenicol, were generated by targeted mutagenesis. Growth and photosynthetic characteristics of a selected mutant strain under photoautotrophic conditions were similar to those of the wild type, suggesting that the function of PsaL is dispensable for photosynthesis in Synechocystis sp. PCC 6803. Western analysis and subunit composition of purified photosystem I revealed that the mutant strain contained other subunits of photosystem I in thylakoid membranes and in the assembled complex. When photosystem II activity was inhibited and glucose was supplied in the medium, mutant strains grew faster than the wild type. Under these conditions of growth, re-reduction of P700 in the mutant cells, but not in the wild type cells, showed a component with an uncharacteristically rapid half-time.

Amino Acid Sequence↗

Arginine vasopressin produces renal vasodilation via V2 receptors in conscious dogs.

In conscious dogs, 36-h water deprivation induced a significant increase in renal blood flow (RBF) with elevation of the plasma arginine vasopressin (AVP) concentration to 9.6 +/- 1.8 pg/ml. To simulate such a condition, a mild elevation of plasma AVP was produced by infusing AVP intravenously at a dose of 0.1 ng.kg-1.min-1 for 20 min. The plasma AVP concentration then increased to 6.8 +/- 0.7 pg/ml. This dose of AVP increased the RBF by 21.7 +/- 2.6% and decreased the renal vascular resistance by 18.1 +/- 2.3% without significant changes in mean arterial pressure, cardiac output, or heart rate. The mechanism of this renal vasodilatory action was examined using newly developed, orally effective, selective AVP antagonists OPC-21268 (a V1-receptor antagonist) and OPC-31260 (a V2-receptor antagonist). In 36-h water-deprived dogs, V2-receptor blockade with OPC-31260 significantly decreased the RBF by 20.5 +/- 2.6% without significant changes in cardiac output. The exogenous AVP-induced renal vasodilatory response tended to be augmented when V1 receptors were blocked by pretreatment with OPC-21268, but the change did not achieve statistical significance. On the other hand, V2-receptor blockade by either pretreatment with OPC-31260 or simultaneous infusion of OPC-31260 inhibited this vasodilatory response. Furthermore, intravenous infusion of 1-desamino-8-D-arginine vasopressin (DDAVP) at a dose of 0.3 ng.kg-1 x min-1 for 20 min significantly increased the RBF by 36.5 +/- 1.7%, and this DDAVP-induced renal vasodilation was inhibited by simultaneous infusion of V2-receptor antagonist.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Case report: hypertension in Cushing's syndrome.

Pathogenesis of hypertension in Cushing's syndrome has remained controversial. A 56-year-old Japanese man with Cushing's syndrome due to adrenal carcinoma has been followed up for more than 6 years. During the followup period, left adrenalectomy and hemihepatectomy due to metastatic lesion were performed. Blood pressure, serum cortisol, and urinary excretion of 17-OHCS, as well as other routine biochemicals, have been measured periodically. These data revealed that there is a marked correlation between the levels of blood pressure and serum cortisol or urinary excretion of 17-OHCS. This finding suggests that cortisol production by tumor is a determinant factor in hypertension in Cushing's syndrome.

Adrenal Gland Neoplasms↗

Depressor systems contribute to hypertension induced by glucocorticoid excess in dogs.

OBJECTIVE: The aim of this study was to investigate the role of depressor systems in glucocorticoid-induced hypertension. METHODS: The serial changes in cardiorenal hemodynamics, urinary excretions of kallikrein and prostaglandins (PGE2 and the prostacyclin derivative 6-keto-PGF1 alpha) before, and during the administration of both low and high doses of dexamethasone (9 alpha-fluoro-16 alpha-methylprednisolone) and after the cessation of dexamethasone were examined in conscious trained dogs. In addition, pressor responses to prostaglandin, bradykinin, bradykinin antagonist and indomethacin were studied during the administration of dexamethasone. RESULTS: High-dose dexamethasone induced a significant elevation in mean arterial pressure (MAP) that was accompanied by a significant reduction in the urinary excretion of kallikrein, PGE2 and 6-keto-PGF1 alpha. In contrast, low-dose dexamethasone treatment had no significant effect upon MAP but induced a transient elevation in the urinary excretion of kallikrein, PGE2 and 6-keto-PGF1 alpha. Furthermore, additional oral administration of indomethacin produced a significant elevation in MAP in dogs treated with low-dose dexamethasone; but did not affect the hemodynamics of animals with high-dose dexamethasone. Whilst i.v. administration of either bradykinin or prostacyclin induced a significant reduction in MAP in high-dose but not low-dose dexamethasone-treated dogs, administration of a competitive bradykinin antagonist, D-Arg-[Hyp3, Thi5,8, D-Phe7]-bradykinin induced a significant elevation in MAP in low-dose but not high-dose dexamethasone-treated dogs. CONCLUSION: Depressor systems play an important role in regulation of blood pressure in glucocorticoid-treated dogs.

Animals↗

Usefulness of thyroglobulin antibody detected by ultrasensitive enzyme immunoassay: a good parameter for immune surveillance in healthy subjects and for prediction of post-partum thyroid dysfunction.

OBJECTIVE: Using newly developed ultrasensitive enzyme immunoassay (EIA) for thyroglobulin antibody (TgAb), we have evaluated physiological and pathological implications of the antibody in healthy subjects as well as in autoimmune thyroid diseases. MEASUREMENTS: This EIA was based on the immune complex transfer method, and was 10(4)-fold more sensitive compared with the conventional haemagglutination assay (HA); the detection limit was 0.1 micrograms IgG/I, and the specificity of the assay was confirmed from the unequivocal decrease in the fluorescence intensity by the preincubation of test serum with Tg and/or inactive beta-D-galactosidase which blocks antibodies to the enzyme. RESULTS: TgAb was detectable in 159 (91%) of 175 healthy subjects aged 3rd to 7th decade (96 men and 79 women), and did not exhibit age or sex-associated change. In nine healthy women, the TgAb level significantly decreased as pregnancy progressed but increased transiently after delivery. TgAb was detectable in 52 (98%) of 53 patients with Graves' disease and all (100%) of 107 patients with chronic thyroiditis. Abnormal high TgAb values (> 40 micrograms/I), determined from the 95th percentile in healthy subjects, were shown in 40 (75%) with the former disease and 94 (88%) with the latter disease. Moreover, in 14 goitrous patients with biopsy-proved chronic thyroiditis with negative HA results, 12 (86%) showed abnormal high TgAb levels. In 69 patients with post-partum thyrotoxicosis in Graves' disease, 15 (79%) of 19 patients with the TgAb level of more than 2 x 10(3) micrograms/I in early pregnancy showed destructive thyrotoxicosis and 46 (92%) of 50 with less than this level showed stimulative thyrotoxicosis. This TgAb test could discriminate the two types of thyrotoxicosis more clearly than could the conventional TGHA test. In chronic thyroiditis, the mean TgAb value in early pregnancy was significantly higher in patients with postpartum hypothyroidism than in those without thyroid dysfunction. Hypothyroidism developed in 80% of the patients with a TgAb value of more than 10(3) micrograms/I. CONCLUSIONS: The ultrasensitive TgAb EIA was useful for detecting the physiological changes in autoantibody formation in healthy subjects and the TgAb value was useful for predicting post-partum thyroid dysfunction in autoimmune thyroid diseases. This EIA is useful for the evaluation of the immune surveillance in patients with autoimmune thyroid diseases as well as in healthy subjects.

Adult↗

Use of inactive beta-D-galactosidase for elimination of interference by anti-beta-D-galactosidase antibodies in immune complex transfer enzyme immunoassay for anti-thyroglobulin IgG in serum using beta-D-galactosidase from Escherichia coli as label.

A novel enzyme immunoassay (immune complex transfer enzyme immunoassay) for anti-thyroglobulin IgG using beta-D-galactosidase from Escherichia coli as label was reported previously. This immunoassay was highly sensitive in demonstrating anti-thyroglobulin IgG not only in all patients with Graves' disease and chronic thyroiditis but also in a large proportion of healthy subjects. However, the detection of anti-thyroglobulin IgG at low levels in some serum samples was difficult, probably due to the presence of anti-beta-D-galactosidase antibodies. In the present study, the use of inactive beta-D-galactosidase was tested for elimination of interference by anti-beta-D-galactosidase antibodies. Preincubation of serum samples with excess of inactive beta-D-galactosidase resulted in sufficiently low backgrounds to detect low levels of anti-thyroglobulin IgG with little effect on the dose-response of anti-thyroglobulin IgG. As a result, it was revealed that anti-thyroglobulin IgG was present in almost all healthy subjects as well as all patients with Graves' disease and chronic thyroiditis.

Adult↗