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Biomedical subjects

T Ohtomo

Publications and source records attributed to T Ohtomo.

At least 37 records · Page 2Linked to original sources
PubMed1995

Humanization of mouse ONS-M21 antibody with the aid of hybrid variable regions.

Mouse monoclonal antibody, ONS-M21, directed against human medulloblastoma cells, has been humanized by complementarity determining region (CDR) grafting. A humanized ONS-M21 VH region, comparable to the original mouse ONS-M21 VH region, was easily constructed based on framework regions (FRs) 1, 2 and 3 from human EU antibody and on FR4 from human ND antibody. Five alterations in the FRs were made at amino acids 27, 28, 29, 30 and 94 which are all part of the canonical structure for CDR1 (H1). The humanized ONS-M21 VL regions were constructed based on the FRs from human REI antibody. We first identified five amino acid residues in the FRs at positions 20, 21, 71, 73 and 87 as having a possible adverse influences on antigen binding. None of the versions with a variety of combinations at these five positions showed any bindings to antigen. In order to identify the mouse residues that must be retained in the human FRs, hybrid VL regions were constructed by joining the mouse ONS-M21 VL region and the first humanized version within CDR2. The hybrid VL regions revealed that residues in FR1 and/or FR2 were critical in creating a functional antigen binding site. Redesigning several versions with alterations in FR1 and FR2 revealed that the Pro-46 residue was the only critical residue for creating an antigen binding site. This approach should be helpful in identifying key residues in difficult cases of antibody humanization.

Amino Acid Sequence↗
PubMed1992

[Study on uric acid metabolism in patients with primary aldosteronism].

This study was conducted to elucidate renal uric acid metabolism in patients with primary aldosteronism (PA;16 cases) as compared with normotensive subjects (NT;25 cases) and essential hypertensives (EHT;51 cases). All subjects were hospitalized and received a regular diet(Na;120 mEq,K;75 mEq,daily) for more than two weeks, after which renal clearance tests were performed, and serum uric acid(SUA), fractional excretions of uric acid(FEUA), sodium(FENa), and inorganic phosphorus(FEP) were evaluated. Plasma aldosterone concentration(PAC) was measured in 16 patients with PA before treatment and in 8 patients after adrenalectomy. SUA was lower in PA than in either NT or EHT, and this lowering was more obvious in male subjects. In NT, PA and EHT, FEUA, an index of renal excretion of uric acid, correlated negatively with SUA and positively with FENa and FEP, which reflected sodium reabsorption at the renal total tubules and proximal tubules, respectively. Although FENa was nearly the same in all the three groups, FEUA and FEP were significantly higher in PA than in EHT or NT. However, no significant correlation was found between PAC and SUA or FEUA in PA. In PA a significant increase of SUA, and decreases of FEUA and FEP were observed after the removal of adenoma compared to before the surgery. These results suggest that uric acid transport might be closely related to sodium transport in the renal tubules, particularly at the proximal site, and also lead to the conclusion that the lower SUA in PA resulted from the suppression of reabsorption and/or an enhancement of secretion of uric acid in the proximal tubules, being related to the so-called escape phenomenon.

Adenoma↗
PubMed1992

[Effects of intravenously infused magnesium on renal calcium metabolism and plasma parathyroid hormone in patients with essential hypertension].

This study aimed to elucidate the effects of intravenously infused magnesium on renal calcium and sodium metabolism in patients with essential hypertension. Mean arterial pressure (MAP), heart rate (HR), urine volume (UV), endogenous creatinine clearance (Ccr), urinary excretion of calcium (UCaV) and sodium (UNaV), fractional excretion of calcium (FECa) and sodium (FENa), plasma ionized calcium (pCa2+) and parathyroid hormone(PTH) were measured before and after intravenous infusion of 10% magnesium sulfate (initial dose: Mg 13.5mg/m2.BSA/15 min.: maintenance dose: Mg 2.7mg/m2.BSA/105min) in 6 normotensive subjects (NT) and 13 mild-to-moderate essential hypertensives (EHT). After the magnesium infusion, significant increases of UV, UCaV, UNaV, FECa and FENa, and a significant decrease of PTH were observed in both NT and EHT while MAP and HR did not change in either group. PCa2+ significantly decreased and Ccr tended to increase only in EHT. Although no significant difference was found in the change in Ccr (delta Ccr) or PTH (delta PTH) between NT and EHT, the changes of UCaV (delta UCaV), UNaV (delta UNaV), FECa (delta FECa) and FENa (delta FENa) were greater in EHT than each in NT. A positive correlation was found between delta UCaV and delta FECa, as well as delta UCaV and delta Ccr, but the former was more remarkable in both groups. In addition, delta UCaV was positively correlated with delta FENa in EHT, but not in NT. No significant relationship was observed between delta UCaV and delta PTH in either group.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium↗
PubMed1991

[The role of the renal dopaminergic and the prostaglandin systems in renal uric acid metabolism in patients with essential hypertension].

The present study aimed to elucidate the role of renal dopaminergic and prostaglandin (PG) systems in renal uric acid metabolism in essential hypertension. Mean arterial pressure (MAP), heart rate (HR), endogenous creatinine clearance (Ccr), serum uric acid (SUA), urinary excretions of uric acid (UUAV) and sodium (UNaV), fractional excretions of uric acid (FEUA) and sodium (FENa), plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were measured before and after intravenous injection of a dopamine receptor antagonist, metoclopramide (MCP: 8 mg/m2.BSA), or before and after a single oral administration of prostaglandin synthesis inhibitor, indomethacin (IM: 75 mg), in 34 mild-to-moderate essential hypertensives (EHT). MCP injection or acute oral administration of IM caused significant decreases of UNaV and FENa in each group, whereas MAP, HR and SUA did not change in either group. Significant decreases in Ccr, UUAV and FEUA and increases in PRA and PAC were demonstrated by MCP injection, while no significant changes in these parameters were revealed by IM administration. There was a significant positive correlation between delta UUAV and delta Ccr or delta FEUA in both groups. In addition, a close positive correlation between delta UUAV and delta UNaV as well as between delta FEUA and delta FENa was found in the MCP group, but not in the IM group. On the other hand, no significant correlation was observed between delta UUAV and delta PRA or delta PAC in either MCP or IM administration. The decreases of UUAV and FEUA were significantly greater in MCP than in IM administration, despite similar changes in Ccr, UNaV and FENa between the two procedures. These data suggest that the endogenous renal dopaminergic system may contribute to renal uric acid metabolism, which is rather closely related to sodium handling in essential hypertension than the prostaglandin system. Furthermore, the attenuated renal dopaminergic activity may contribute to the elevation of serum uric acid level in patients with essential hypertension.

Adult↗
PubMed1991

Platelet aggregation induced by strains of various species of coagulase-negative staphylococci.

Major species of coagulase-negative staphylococci (CNS) were tested for their ability to induce platelet aggregation in rabbit platelet-rich plasma (PRP). Among 11 species of CNS tested, a majority of the strains of 10 species of CNS (S. epidermidis, S. simulans, S. capitis, S. hyicus, S. sciuri, S. cohnii, S. xylosus, S. hominis, S. haemolyticus, S. warneri) caused induction of the platelet aggregation and serotonin release, while S. saprophyticus did not show such activity. The addition of aspirin (10 mM) or quinacrine (1 mM) to PRP resulted in no remarkable effect on the platelet aggregation induced by these strains and it was shown that the platelet aggregation did not require arachidonate pathways. Complement system components were shown to be one of the plasma factors required for platelet aggregation by ten strains of each species of CNS. The bacterial substance participating in the platelet aggregation by ten species of CNS tested was indicated to be heat-stable and trypsin-resistant, while the activity of a strain of S. epidermidis was susceptible to trypsin.

Animals↗
PubMed1990

Inhibition of platelet aggregation by a whole cell extract from strains of group B streptococcus.

A whole cell extract (HCl-Ext) from strains of group B streptococci (GBS) possessing fibrinogen binding activity prevented the platelet aggregation induced with adenosine 5'-diphosphate (ADP), collagen and thrombin, while aggregation by epinephrine and ristocetin was slightly inhibited and arachidonic acid-induced platelet aggregation was not affected whatsoever. When the HCl-Ext was added after commencement of the aggregation, deaggregation was observed in cases induced by ADP, collagen, and thrombin. By precoating the washed platelets with HCl-Ext, both of ADP- and collagen-induced platelet aggregation were suppressed. The active factor in the HCl-Ext seemed to be undialyzable, trypsin-susceptible, and proteinaceous substance, unlike GBS polysaccharide type antigen.

Fibrinogen↗
PubMed1990

Immunochemical characterization and biological properties of a cell surface antigen extracted from encapsulated Staphylococcus epidermidis strain SE-10.

Protection inducing antigen (PIA) was mechanically extracted from Staphylococcus epidermidis (encapsulated strain SE-10) and purified by DEAE-Sephadex A 25 (C1- form) ion exchange chromatography. Major carbohydrate constituents of PIA were galactose, glucose, and N-acetylglucosamine at the molar ratio 1.00:0.96:0.78. Antigenic activity was considerably reduced after sodium metaperiodate oxidation, however, pronase digestion was not effective. N-acetylglucosamine residues were shown to be closely related to the antigenic determinant. No cross reactivity to PIAs from other encapsulated strains of S. epidermidis was found which indicates type specificity. Protection of mice after immunization and enhancement of human granulocyte function suggests that PIA might be considered to be a biological response modifying substance.

Antigens, Bacterial↗
PubMed1990

Isolation of a serologically different compact-colony-forming active substance from strains of Staphylococcus aureus.

To observe the possible serological heterogeneity of compact-colony-forming active substance (CCFAS), heat-killed vaccines were prepared by two strains of Staphylococcus aureus, strains SMU 1-46 and SMU 7931, cultured in 0.03 M trishydrochloride-buffered brain heart infusion, pH 8.4. After immunization with the vaccine in rabbits, antibody responses were observed during a period of six weeks after the immunization either by homologous and heterologous organisms using alkaline serum-soft agar technique. The results showed that remarkable antibody production was shown only against homologous strain, but not against heterologous strain. The antibodies were absorbed out only with highly purified preparation of CCFAS extracted from homologous strain and not with heterologous CCFAS. Differences of the major chemical composition of the substances showed that highly purified CCFAS extracted from strain SMU 7931 contained 2.84 and 2.04 times higher amounts of galactose and 2-amino-2-deoxy-D-galacturonic acid than those of CCFAS obtained from strain SMU 1-46.

Agar↗
PubMed1990

Binding of staphylococcal cell surface polysaccharide to human fibrinogen.

The interaction between the binding site of a polysaccharide (called compact colony forming active substance (CCFAS)), obtained from the cell surface of a strain of Staphylococcus, and human fibrinogen (HF) was investigated. The CCFAS was found to bind specifically to both the B beta and gamma chains of HF at pH 7.0 and 8.0, and the A alpha chain at pH 5.0. The binding of CCFAS with fibrinogen fragments obtained by digestion with plasmin were also investigated. Fragments with Mr of 55,000, 24,000, and 19,000 were the major bands precipitated by CCFAS at pH 7.0 and 8.0. Fragments with Mr of 85,000 and 75,000 bound to CCFAS at pH 5.0. Binding of CCFAS (7 micrograms) with fibrinogen could be inhibited by 1.2 micrograms of B beta chain and 1.5 micrograms gamma chain at alkaline pH or 6.2 micrograms of the A alpha chain at pH 5.0. CCFAS was, therefore, assumed to be specifically bonded with HF molecules, in the alkaline range at least, resulting in compact colony forming activity in serum soft agar and paracoagulation.

Cell Membrane↗
PubMed1990

[Tetralogy of Fallot revealed by autopsy in an elderly subject].

A 62-year-old women had a history of cyanosis and easy fatigability from school age but had refused medical examinations. She was admitted to our department with exacerbation of dyspnea at the age of 59. Laboratory tests showed hypoxia complicated with polycythemia with 35 mmHg of PaO2, 8.5 x 10(6) erythrocytes per mm3. The systolic pressure of the right ventricle was 155 mmHg. RI angio demonstrated a high degree of the right-to-left shunt at the ventricular level. The patient was given oxygen therapy at home without diagnosis of tetralogy of Fallot (TOF) and eventually died at the age of 62. Tetralogy of Fallot was diagnosed at autopsy. Pulmonary stenosis of this case was located in infundibulum. The lining of the infundibular inlet was constituted of the thick fibrous tissue which remarkably augmented the pulmonic stenosis. Although the autopsy findings were considered to be relatively mild TOF, the death was presumed to be caused by development of the infundibular stenosis due to formation of fibrous tissue. This is the oldest patient in Japanese medical literature to be identified by cardiac catheterization and autopsy finding as a case of TOF.

Age Factors↗
PubMed1989

[The role of the Na, K-ATPase inhibitor in renal sodium handling in patients with essential hypertension].

The present study aimed to elucidate the role of Na, K-ATPase inhibitor in renal sodium metabolism in essential hypertension. Mean arterial pressure (MAP), heart rate(HR), urine volume (UV), urinary excretion of sodium (UNaV), endogenous creatinine clearance (Ccr), fractional excretion of sodium (FENa), plasma renin activity(PRA) plasma aldosterone concentration(PAC), plasma noradrenaline concentration (PNA) and urinary excretion of noradrenaline(UNA) were measured before and after intravenous injection of ouabain (0.1 mg/m2.BSA) in 12 normotensive(NT) and 22 mild-to-moderate essential hypertensive subjects(EHT). Following ouabain injection, UV, UNaV FENa significantly increased, but PRA decreased, in both NT and EHT. MAP, HR, Ccr, PNA, and UNA did not change significantly in either group. On the other hand, a significant decrease in PAC was observed in NT, but not in EHT. The changes of UNaV and FENa were significantly attenuated in EHT as compared to NT. No significant difference in change of MAP, HR, UV, Ccr, PNA, UNA, or PRA was demonstrated between NT and EHT. A significantly positive correlation was found between delta UNaV and delta FENa in both NT and EHT, while no significant correlation was observed between delta UNaV and delta MAP, delta UV, delta Ccr, delta PRA, delta PAC, delta PNA and delta UNA in either group. These results suggest that 1) Na, K-ATPase inhibitor clearly augments natriuresis by suppression of sodium reabsorption in renal tubules, 2) since this augmentation was attenuated, there is an elevation of endogenous Na, K-ATPase inhibitor(s) should be considered in EHT, and 3) an increase of the inhibitor might participate to the hypertensive mechanism in EHT.

Adult↗
PubMed1989

[The effects of intravenous infused magnesium on hemodynamics and renal water-sodium metabolism in patients with essential hypertension].

Mean arterial pressure (MAP), heart rate (HR), urine volume (UV), urinary excretion of sodium (UNaV), endogenous creatinine clearance (Ccr), fractional excretion of sodium (FENa) were measured before and after intravenous infusion of 10% magnesium sulfate (an initial dose: Mg 13.5 mg/m2.BSA/15 min; a maintenance dose: Mg 2.7 mg/m2.BSA/105 min) in 6 normotensive subjects (NT) and 12 mild-to-moderate essential hypertensives (EHT). Following magnesium infusion, serum magnesium concentration (s-Mg) increased and reached the level of about 1.8 times basal value. Significant increases of UV, UNaV and FENa in both NT and EHT, and a similar tendency of Ccr in EHT were observed, while no significant change in MAP nor HR was found in the two groups. The changes in UNaV (delta UNaV) were positively correlated with those in FENa (delta FENa) and a similar tendency was shown between delta UNaV and change in Ccr (delta Ccr) in all subjects. While there was no significant percentage change of s-Mg (% delta s-Mg) nor of Ccr (% delta Ccr), those of UNaV (% delta UNaV) and FENa (% delta FENa) were significantly greater in EHT. It is concluded from these findings that magnesium infusion produces diuresis and the natriuresis which might result from suppression of renal tubular reabsorption of sodium, without any change in systemic hemodynamics in NT and EHT. The pronounced natriuretic response to magnesium in EHT might contribute to the hypotensive mechanism of magnesium loading in EHT.

Female↗
PubMed1988

Comparison of compact colony-forming activity and paracoagulation activity of strains of Staphylococcus aureus in serum and plasmas of various animals.

Using 20 strains of Staphylococcus aureus isolated from clinical specimens, the compact colony-forming activity (CCFA) in serum-soft agar (SSA) in sera from various animals and the paracoagulation (PC) activity of the compact colony-forming active substance (CCFAS) extracted from these strains were investigated. The results of this comparative study revealed that the CCFA and PC of S. aureus for sera from various animals in SSA were different, not only among different strains but also in the same strains. In addition, the effect of galactose and calcium ions on the PC activity of these strains in experiments employing human fibrinogen permitted the recognition of these groups of S. aureus strains. In one group, PC activity was decreased by galactose but unaffected by calcium ions, in the second group PC activity was unaffected by galactose but increased by calcium ions, while in the third group it was unaffected by both. These results suggest the possibility of heterogeneity of CCFA among different strains of S. aureus.

Animals↗
PubMed1988

Adhesion of Staphylococcus aureus to fibrinogen, collagen and lectin in relation to cell surface structure.

The adherence of an encapsulated strain of Staphylococcus aureus, S-P, and its variants to fibrinogen-, collagen-, and lectin-coated hydroxyapatite were compared. The parent strain, S-P, possesses a large capsule while its variants S-A and S-B possess a small capsule and microcapsule, respectively. The third variant, S-C, has no capsule. Adherence to proteinaceous substances varied according to the strains. While all four strains showed a similar degree of adhesion to collagen, the adhesion of strains S-A, S-B and S-C to fibrinogen and lectin differed from those of strain S-P. The effect of physical and enzymatic pretreatment of the strains on adhesion characteristics was measured. Generally, these results suggest that both carbohydrate and protein moieties on cell surface may be involved in adherence. In addition, the inhibition of adhesion by cell-surface polymers and monosaccharides was measured. The inhibition of adhesion of large capsulated (S-P) and unencapsulated (S-C) strains by proteinaceous substances differed. The large capsulated strain (S-P) of S. aureus had different adherence capacities in early-, mid-, or late log phases of growth, whereas the adherence capacities of the unencapsulated strain S-C remained nearly constant.

Bacterial Adhesion↗
PubMed1988

Outermost-cell-surface changes in an encapsulated strain of Staphylococcus aureus after preservation by freeze-drying.

The effects of drying time during freeze-drying on the outermost cell surface of an encapsulated strain of Staphylococcus aureus S-7 (Smith, diffuse) were investigated, with special attention paid to capsule and slime production. To quantify capsule and slime production, capsule antigen production and cellular characteristics such as growth type in serum-soft agar, cell volume index, and clumping factor reaction were examined. After freeze-drying the colonial morphology of strain S-7 was altered from a diffuse to a compact type in serum-soft agar. In accordance with these changes, the titer of the clumping factor reaction increased while the cell volume index, capsule and slime production, and capsule antigen production were markedly decreased in parallel with the period of freeze-drying. The ability of the strain to adhere to collagen, fibrinogen, and soybean lectin was also compared before and after freeze-drying. Fibrinogen levels slightly increased when 10% skim milk and 2% honey were used as cryoprotective agents and showed a remarkable increase when 0.05 M phosphate buffer was used as a control. Also, the ability of strain S-7 to adhere to soybean lectin declined, whereas no changes were observed for collagen under any conditions. Strain S-7 was phage nontypable before freeze-drying but the number of typable cells increased after freeze-drying; phage-typable cells reacted to phage 52 alone after 5 h of freeze-drying, but additional cells also proved to be phage typable to phage 42E after 10 h. Electron micrographs indicated that strain S-7, an encapsulated strain, was converted to an unencapsulated state after freeze-drying.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial Adhesion↗