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Biomedical subjects

R Sakai

Publications and source records attributed to R Sakai.

At least 181 records · Page 10Linked to original sources
PubMed1987

Development and application of an enzyme-linked immunosorbent assay for acid stable trypsin inhibitor (ASTI) in human plasma.

An enzyme-linked immunosorbent assay (ELISA) for acid-stable trypsin inhibitor was developed using goat antibodies raised against urinary trypsin inhibitor purified from normal human urine. The assay was highly sensitive and precise, and gave reproducible results in the range of 1-1,000 ng/ml. The specificity and sensitivity of this assay permitted measurement of a low content of acid stable trypsin inhibitor in different tissue extracts and body fluids. Using the new method, the mean level in plasma samples taken from healthy individuals was found to be 54.9 +/- 17.4 (mean +/- SD) micrograms/ml and that of acid-treated plasma was 11.5 +/- 3.0 micrograms/ml (n = 27). The calculated specific activity of acid stable trypsin inhibitor in acid treated plasma was 300 U/mg, while that of highly purified inhibitor is 2,100 U/mg. These results suggest the presence of both acid unstable protein having the same antigenicity as urinary trypsin inhibitor and the inactive form of acid stable trypsin inhibitor.

Enzyme-Linked Immunosorbent Assay↗
PubMed1987

[Studies on the half-life of C-terminal parathyroid hormone in chronic renal failure].

Subtotal parathyroidectomy (PTX) was performed for patients with hyperparathyroidism associated with chronic renal failure, and from sequential determination of PTH after PTX, the half-life of 2 different C-PTH was calculated. The half-life (T 1/2) of 46 approximately 84 PTH and 65 approximately 84 PTH was 18.1 +/- 3.9 and 14.0 +/- 2.2 hours (Mean +/- SD) respectively. Half-life of both C-PTH was markedly prolonged compared with that (30 approximately 60 minutes) of healthy subjects. It is considered that the longer half-life of 46 approximately 84 PTH than 65 approximately 84 PTH might be attributed to the difference of molecular weight, degrading enzymes and operative procedures. Determined value of C-PTH in chronic renal failure should be evaluated in consideration of prolonged metabolic clearance of C-PTH.

Adult↗
PubMed1986

Amiloride inhibition of DNA synthesis and immunoglobulin production by activated human peripheral blood mononuclear cells is independent of sodium/hydrogen antiport.

Activation of sodium/proton (Na+/H+) antiport activity has been shown to occur as an early event in mitogenesis. Because amiloride inhibits Na+/H+ antiport activity, it is hypothesized that mitogenesis may be inhibited by amiloride. In this work, we examined the effect of amiloride on DNA synthesis as measured by [3H]thymidine uptake and immunoglobulin (Ig) production as measured by an ELISA system in human peripheral blood mononuclear cells (PBM). Amiloride at 100 microM concentration inhibited irradiated Raji cell (*R)-activated and phytohemagglutinin-P (PHA-P)-stimulated DNA synthesis by 50 +/- 11% and 72 +/- 12%, respectively. IgG production was inhibited by 71% at 100 microM amiloride concentration in *R-activated PBM. This concentration of amiloride inhibited Na+/H+ antiport activity by 92%. Because amiloride is known to inhibit other pre-replicative cellular functions such as protein synthesis, we used an amiloride analogue, dimethylamiloride, which inhibited Na+/H+ antiport activity by 90% at a concentration of 1 microM without inhibition of PBM Ig or DNA synthesis. Furthermore, neither PHA-P nor *R-stimulated PBM demonstrated an intracellular alkalinization even after 6 hr of stimulation. Similarly, T cell-enriched or B cell-enriched populations did not show intracellular alkalinization after PHA-P or *R activation. Thus, it appears that Na+/H+ antiport activation is not an early event in PBM mitogenesis. The inhibition of mitogenesis by amiloride may be due to abrogation of premitotic events such as protein synthesis.

Adult↗
PubMed1985

Quantitation of circulating immune complexes in human serum by the Raji cell and F(ab')2 anti-C3 micro enzyme immunoassays.

Two micro enzyme immunoassays (microEIA) for circulating immune complexes (CICs) are described. The Raji cell microEIA was similar in sensitivity, reproducibility and specificity to the Raji radioimmunoassay. The F(ab')2 anti-C3 microEIA was comparable to the 2 Raji cell assays. The 2 microEIAs for CICs were used to analyze sera from patients with systemic lupus erythematosus (SLE), the acquired immune deficiency syndrome (AIDS) and from hemophiliacs with AIDS-like symptoms. The microEIAs were very sensitive in detecting CICs in pathologic sera. In contrast, only 3% of normals (n = 30) were positive in the Raji microEIA while none were positive in the F(ab')2 anti-C3 microEIA. The initial high positivity of some normals (9/30) in the F(ab')2 microEIA was due to bovine serum albumin (BSA)-anti-BSA immune complex formation in vitro and was corrected when human albumin was used in buffer preparation instead of BSA. The reagents required for the microEIAs are more stable and less expensive than those required for the RIAs and the need for facilities to deal with 125-labeling and disposal is avoided.

Acquired Immunodeficiency Syndrome↗
PubMed1985

1,25-Dihydroxyvitamin D3 suppresses human T helper/inducer lymphocyte activity in vitro.

The active form of vitamin D3, 1 alpha,25-dihydroxyvitamin D3 (1,25-(OH)2-D3), suppresses in vitro immunoglobulin (Ig) production by activated peripheral blood mononuclear cells (PBM) from normal human subjects by inhibiting T helper/inducer TH cell activity. Normal PBM were fractionated into B, TH and T suppressor/cytotoxic (Ts) cells by fluorescence-activated cell sorting techniques. The resultant subsets were activated with mitogens and were cultured in the presence or absence of a receptor-saturating concentration of 1,25-(OH)2-D3. The sterol reduced [3H]thymidine incorporation in TH cells by 56%, with no effect on Ts or B cells. When 1,25-(OH)2-D3-treated TH cells were co-cultured with untreated B cells and culture supernatants assayed for Ig production, 1,25-(OH)2-D3 abrogated the inducing effect of TH cells on Ig synthesis by B cells. There was no inhibitory effect of the sterol on Ts or B cell activity. In addition, 1,25-(OH)2-D3 produced a dramatic inhibition of interleukin 2 (IL 2) production by activated PBM, but did not inhibit IL 2 receptor generation by these cells. Other vitamin D metabolites tested did not produce this effect. These results suggest that the TH lymphocyte is the specific cellular target for the immunoinhibitory effects of 1,25-(OH)2-D3.

Animals↗
PubMed1985

A point survey of periurban and urban malaria in Karachi.

A point survey of malaria in Karachi revealed a concentration of malaria cases in the periurban perimeter and marginal areas where immigrating groups, including Afghan refugees and Biharis from Bangladesh are concentrated. Populations of Anopheles stephensi, Karachi's main vector, were low, and were feeding chiefly on buffaloes which are also concentrated along the periurban perimeter. Maintenance of malaria transmission in periurban zones may depend on immigration of susceptibles, bovid hosts which help maintain zoophilic vector populations, and mosquito breeding sites in water tanks or buffalo hoofprints. The vector's switch to man-biting behaviour may occur either due to a 'spillover' effect from buffalo corrals to surrounding houses, or when buffaloes become less available for biting. Four types of chromosome inversions were found in the Karachi An. stephensi; as this species is not a vector in similar habitats in Lahore and Pondicherry where such inversions are not prevalent, it is likely that its status as a vector is related to chromosomal polymorphism influencing behaviour.

Adolescent↗
PubMed1984

A study on chronologic change of the relationship between cigarette smoking and lung cancer based on autopsy diagnosis.

Human cases autopsied at the Department of Pathology, University of Tokyo, were studied to investigate the chronologic changes in the relationship between cigarette smoking and lung cancer occurrence. The results obtained were as follows: (1) it was confirmed that the incidence of lung cancer was significantly higher among cigarette smokers than among nonsmokers, and that there was a definite dose-response relationship between the quantity of cigarettes smoked and the occurrence of lung cancer; and (2) over the time span studied, the incidence of lung cancer among autopsies showed a remarkable increase. However, this tendency was seen in both cigarette smokers and nonsmokers, and in fact, the increase was comparatively higher in the latter group. It should be stressed that the relative importance of cigarette smoking in human pulmonary carcinogenesis seems to have decreased in the past 40 years or so, and factors other than cigarette smoking seems to have become more important.

Adult↗
PubMed1984

False-negative anti-DNA antibody activity in infantile systemic lupus erythematosus (SLE).

A 2.5-month-old previously healthy female infant presented with serositis , nephrotic syndrome, progressive renal failure, anemia, and thrombocytopenia. Renal biopsy revealed a proliferative glomerulonephritis with glomerular and extraglomerular deposits of IgG, IgM, C3, and Clq by direct immunofluorescence (IF) techniques. Skin biopsy was positive for IgG and C3 deposits in the dermal-epidermal junction by IF. Despite strong clinical and pathological criteria for systemic lupus erythematosus (SLE), tests for antinuclear and anti-DNA antibodies were negative. Circulating immune complexes (CICs) were detected in three separate assay systems. Immunochemical analysis of isolated CICs showed that anti-DNA antibody was present. Analysis of kidney biopsy material by antigen-specific solubilization techniques showed antibodies reactive with ds-DNA in the kidney. These studies confirm that SLE may be a cause of the congenital nephrotic syndrome and that negative SLE serologies may be secondary to binding of available antibody by excess antigen. Analysis of CICs may be helpful in confirming the diagnosis of SLE in seronegative patients.

Adult↗
PubMed1984

Induction of tolerance to factor VIII in a child with a high-titer inhibitor: in vitro and in vivo observations.

High dose factor VIII concentrate was infused over 12 months in a 3-year-old child with hemophilia A and a high-titer inhibitor. This regimen was successful in producing clinical tolerance to the factor VIII and was associated with a fall of inhibitor titer from 85 BU to less than 1 BU. Subsequently, a rise in inhibitor to peak at 3.5 BU correlated with a decrease in infusion dose. In vitro studies using a microdroplet assay for immunoglobulin synthesis in the presence of varying concentrations of factor VIII was carried out prior to the clinical trial. This system indicated that the patient's peripheral blood mononuclear cells were stimulated to release IgG by 0.01 U/ml factor VIII coagulant activity and inhibited at 0.9 U/ml FVIIIc. Lymphocyte subsets were monitored during the course of therapy. The ratio of Leu-3a+/Leu-2a+ (helper/suppressor) varied considerably, fluctuating between a peak of 4.4 and low point of 0.6, with the initial pretrial ratio being 1.2.

Antibodies↗
PubMed1984

1 alpha,25-dihydroxyvitamin D3 suppresses proliferation and immunoglobulin production by normal human peripheral blood mononuclear cells.

Activated B and T lymphocytes from normal human subjects are known to have the specific high-affinity receptor for 1,25-dihydroxyvitamin D3 (1,25-(OH)2-D3). In an attempt to determine a functional role for the sterol in such cells, we studied the effect of 1,25-(OH)2-D3 on DNA synthesis and Ig production by normal human peripheral blood mononuclear (PBM) cells activated in vitro by the polyclonal lymphocyte activators pokeweed mitogen and phytohemagglutinin, and the specific antigen dermatophyton O. A dose-dependent inhibition of [3H]thymidine incorporation was observed in cells incubated with 1,25-(OH)2-D3 in concentrations ranging from 10(-10) to 10(-7) M. Production of IgG and IgM, determined by enzyme-linked immunosorbent assay, was similarly inhibited by increasing concentrations of 1,25-(OH)2-D3. Half-maximal inhibition of DNA and Ig synthesis was found at 10(-10) to 10(-9) M 1,25-(OH)2-D3. This suppressive effect was specific for 1,25-(OH)2-D3; of the other vitamin D metabolites examined, only 10(-7) M 24R,25 dihydroxyvitamin D3 (24,25-(OH)2-D3) had a similar inhibitory effect. 1,25-(OH)2-D3 was not cytotoxic and did not affect unactivated PBMs. These data demonstrate that 1,25-(OH)2-D3 is a potent inhibitor of human PBM Ig production in vitro and suggest that this action is mediated through the hormone's antiproliferative effect on Ig-producing B cells and/or helper T cells.

24,25-Dihydroxyvitamin D 3↗
PubMed1983

Classification of potentially toxic chemicals based on their effects on mitochondrial respiration.

The classification of potentially toxic chemicals including environmental pollutants was made with respect to state 3 and state 4 respiration of mitochondria. The concentration of certain metals for 50% inhibition of respiratory control index (RCI; state 3/state 4) was lower than that of organic compounds tested. Various chemicals including environmental pollutants were classified into four groups by combination of effects on state 3 and state 4 respiration.

Animals↗
PubMed1982

Circulating immune complexes during various forms of renal allograft rejection episodes.

Previous reports on the nephritogenic and immunological enhancing capacity of posttransplant circulating immune complexes (CICs) are conflicting and have been confined to the study of acute rejection episode (AR). This study was undertaken to assess the nephritogenicity of CICs in patients undergoing accelerated acute rejection (AAR) and chronic rejection (CR) episodes. We also assessed the possible role of CICs as mediators of immunological enhancement by assessing CIC levels in long-term-stable allograft recipients. To asses the nephritiogenic role of CICs, 98 CIC determinations were performed on 49 serum samples from 41 pediatric renal transplant recipients using the C1q solid-phase assay (C1q-SPA) and the Raji cell radioimmunoassay (Raji-RIA). Serum samples from normal subjects served as controls. No recipient undergoing AAR had evidence of CICs by eigher assay. 5 of 21 (23.8%) recipients undergoing CR had positive CIC levels in the Raji-RIA, while 4 of 21 (19%) recipients had positive CICs inthe C1q-SPA. There was no statistically significant correlation of CIC levels with long-term allograft function. In addition, there was no evidence supporting antithymocyte globulin as an immunogen in patients demonstrating posttransplant CICs. In summary, CICs do not appear to be an important mediator of AAR or CR episodes, and CICs were not routinely detected in patients with good long-term allograft function.

Antigen-Antibody Complex↗
PubMed1982

The effects of echinatin and its related compounds on the mitochondrial energy transfer reaction.

To investigate the mechanism by which various biological action of licorice root are brought about, the effects of echinatin as a small constituent of Glycyrrhiza echinata and several related compounds on mitochondrial energy transfer reactions were examined. The results obtained were as follows: 1) Echinatin, 4'-hydroxychalcone, chalcone and 3,4'-dihydroxychalcone at a low concentration cause deterioration of respiratory control and oxidative phosphorylation of isolated rat liver mitochondria. 2) Chalcone and 4'-hydroxychalcone stimulate both latent and DNP-ATPase activity of mitochondria. Echinatin inhibits DNP-ATPase activity while stimulating range latent ATPase activity in the low concentration. 3) Chalcone and 4'-hydroxychalcone induce a rapid potassium release from mitochondrial vesicles, while echinatin and 3,4'-dihydroxychalcone have lesser effect than the former two substances. From these results, it can be concluded that echinatin and several related compounds disturb the mitochondrial energy transfer reactions and membrane permeability.

Adenosine Triphosphatases↗