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Biomedical subjects

T Sako

Publications and source records attributed to T Sako.

At least 91 records · Page 5Linked to original sources
PubMed1991

Dieulafoy's ulcer associated with the tortuous caliber persistent arteries: report of three cases.

Many papers have reported that Dieulafoy's ulcer is one of the notorious causes of gastric hemorrhage. Three cases of shallow subfundic ulcers with massive bleeding are reported. The resected specimens have demonstrated that elevated caliber-persistent artery (CPA), a branch of the left gastric artery with few anastomoses, in the base of the ulcer has tortuous penetration from the serosa to submucosa, showing patchy, eccentric intimal fibroelastosis. These findings of CPA are almost the same in both anterior and posterior walls, namely both the ruptured and contralateral sides. Thus, morphogenesis of the ulcer may have originated from anatomical deviation, which is related to regional hypertension aggravated by longterm peristalsis, as well as aging.

Aged↗
PubMed1991

Production of granulocyte-macrophage colony-stimulating factor or GM-CSF-like growth factor by rat thymic epithelial cell line.

An epithelial cell line, IT-45R1, has been established from a thymus of normal Wistar rat and was found to produce growth factor which stimulated the proliferation of bone marrow cells. This growth factor induced the formation of colonies composed of macrophages, granulocytes, or both, in semi-solid medium and stimulated the proliferation of an interleukin 3 (IL3)/granulocyte-macrophage colony-stimulating factor (GM-CSF)-dependent clone. Neither IL3-dependent clone nor IL6-dependent clone responded to IT-45R1 factor. Additionally, IT-45R1 factor acted on both rat and mouse bone marrow cells but not on human bone marrow cells. Molecular weight of IT-45R1 factor was 30 kD and its isoelectric point was 4.5. To determine whether IT-45R1 factor is GM-CSF or not, Northern blot analysis and neutralization with anti-mouse GM-CSF antibody were carried out. IT-45R1 expressed GM-CSF mRNA, but neither M-CSF nor IL6 transcripts. However, antiserum specific for mouse GM-CSF did not neutralize IT-45R1 factor. Taken together, a rat thymic epithelial cell line, IT-45R1, constitutively produces GM-CSF or GM-CSF-like growth factor.

Animals↗
PubMed1991

Neutrophil adherence, phagocytic-nitroblue tetrazolium reduction and chemiluminescence in canine whole blood.

Methods for measuring neutrophil adherence, phagocytic-nitroblue tetrazolium (NBT) reducing activity and chemiluminescence were applied to canine whole blood as means for routine assessment of neutrophil functions. The phagocytic-NBT reduction test appeared to be useful for monitoring the NBT reducing activity of phagocytic cells associated with phagocytic functions. Ethylene diamine tetraacetic acid suppressed both the adherence and the phagocytic-NBT reducing activity of neutrophils. Increased phagocytic-NBT reduction and an enhanced chemiluminescence response were observed in dogs with neutrophilia. These methods provide a rapid and practical screening procedure for measuring selected phagocytic functions in canine whole blood.

Animals↗
PubMed1991

Atrial natriuretic peptide in the dog with mitral regurgitation.

The concentration and molecular form of the plasma atrial natriuretic peptide (ANP) in dogs with mitral regurgitation was investigated. Plasma ANP concentration in dogs with mitral regurgitation was significantly increased (29.4 +/- 1.88 pmol litre-1, n = 40) compared to that in the controls (14.5 +/- 0.62 pmol litre-1, n = 20, P less than 0.01). Molecular forms of plasma ANP were determined by the gel permeation chromatogram. A single peak corresponding to alpha-ANP was detected in the plasma from the controls. However, a peak corresponding to beta-ANP and, or, gamma-ANP was detected in the plasma of the dogs with mitral regurgitation in addition to alpha-ANP. These results suggest that the process of ANP synthesis was altered and excretion of ANP from the heart was enhanced in dogs with mitral regurgitation.

Animals↗
PubMed1991

Novel prlA alleles defective in supporting staphylokinase processing in Escherichia coli.

A class of prlA (secY) alleles of Escherichia coli (prlA4-1 and prlA401) which specifically block the export of staphylokinase has been identified (T. Iino and T. Sako, J. Biol. Chem. 263:19077-19082, 1988; T. Sako and T. Iino, J. Bacteriol. 170:5389-5391, 1988). To determine more precisely the region in PrlA (SecY) effective for the blockage of processing of the staphylokinase precursor, additional prlA mutants which failed to support processing of the staphylokinase precursor were isolated. Two of the five mutant alleles isolated (secY121 and secY161) complemented the temperature sensitivity of a secY24 strain and had no detectable effect on the processing of endogenous secretory proteins of E. coli. In addition, a staphylokinase mutant having glycine in place of serine at position 17 in its signal sequence relieved the detrimental effect of these mutations. All of these characteristics indicate that these two alleles resemble the prlA4-1 and prlA401 alleles. On the other hand, the remaining three mutant alleles (secY47, secY105, and secY112) had no significant PrlA activity. The mutations of secY121 and secY161 were mapped very close to those of prlA4-1 and prlA401 in the presumed transmembrane segment 7 of PrlA. These results indicate that transmembrane segment 7 of PrlA plays a crucial role in the recognition of the staphylokinase signal sequence.

Alleles↗
PubMed1991

Glycated hemoglobin fractions in normal and diabetic dogs measured by high performance liquid chromatography.

We established a new analytical condition to measure the canine glycated hemoglobin by high performance liquid chromatography (HPLC) using cation exchange column. The canine hemoglobin gave five peaks consisting of 2 major and 3 minor hemoglobin fractions such as HbA1a, HbA1b and HbA1c. Measurement was done in 38 clinically normal dogs and 10 diabetic dogs. Mean HbA1c values (% of total Hb) in normal and diabetic dogs were 2.60 and 6.41%, respectively. And mean HbA1 values were 3.58 and 7.41%, respectively. The mean values of the canine HbA1c and HbA1 in diabetic dogs was higher than those in normal dogs, significantly (p less than 0.01). Advantages of the HPLC method and applicability for monitoring effectiveness of insulin therapy in the canine diabetes mellitus are discussed.

Animals↗
PubMed1990

Bovine atrial natriuretic peptide in heart failure.

The present study describes the concentration and molecular form of atrial natriuretic peptide (ANP) in Holstein dairy cattle with mild (bacterial endocarditis; BEC) or severe (dilated cardiomyopathy; DCM) heart failure. Significant increases in plasma concentration of ANP were observed in cattle with DCM (73.3 +/- 16.02 pmol/l, n = 4, P less than 0.01) and BEC (20.6 +/- 3.45 pmol/l, n = 7, P less than 0.05), when compared with those in control cattle (14.5 +/- 1.84 pmol/l, n = 12). The concentration of ANP in cattle with DCM was significantly (P less than 0.01) higher compared with that in cattle with BEC. Plasma concentration of ANP correlated significantly with right atrial pressure (r = 0.95, P less than 0.01) and left ventricular end-diastolic pressure (r = 0.84, P less than 0.01). Gel-permeation chromatography of ANP in plasma and the right atrium from control and cattle with BEC revealed a single peak corresponding to the elution position of authentic human ANP(99-126) in plasma, and two peaks corresponding to those of authentic human ANP(99-126) and pro-ANP in the atrial extract. In cattle with DCM, however, peaks corresponding to the elution positions of authentic human beta-ANP and/or pro-ANP were detected in addition to the peak corresponding to ANP(99-126). The content of ANP in the right atrium of cattle with DCM was significantly (P less than 0.05) increased compared with that in control cattle and those with BEC. The present study therefore suggests that the synthesis and secretion of ANP might be stimulated by atrial distention induced by increased atrial pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Cyclosporin levels in semen of renal transplant patients].

Cyclosporin (CsA) has powerful immunosuppressive properties, and its recent application to organ transplantation has resulted in markedly improved graft survival. However, CsA has certain adverse side effects, the most notable being nephrotoxicity and hepatotoxicity. Among other untoward effects, little is known about the effects of CsA on the reproductive organs. Since good graft survival is now expected with CsA, the long term effect of the drug on the gonads should be monitored carefully, particularly for young recipients. Prior to investigation of the effect of CsA on the testis, the level of CsA in semen of the adult renal transplant patients were measured. Twelve samples of semen from eight recipients, mean age 35 (SD 9), were collected by masturbation in the morning just before taking CsA after more than 5 day abstinence, and it was frozen at -80 degrees C. They had been taking immunosuppressants that were a combination of either CsA and prednisolone, or CsA, azathioprine and prednisolone for 5 to 63 months. The dose of CsA was 3.7 mg/kg to 5.0 mg/kg. The range of the level of serum creatinine was 1.1 mg/dl to 2.9 mg/dl. CsA in whole blood was measured by high performance liquid chromatography (HPLC), and CsA in semen was also measured by HPLC after extracting CsA with diethylether. The level of CsA in semen was 27 ng/ml to 165 ng/ml and that in whole blood was 51 ng/ml to 133 ng/ml. The relation between both levels was linear (r = 0.68, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Changes in plasma cortisol concentration by ages in dogs under ketamine and thiopental anesthesia.

In order to examine the change in adrenocortical responses with age in dogs, 36 healthy beagle dogs were divided by age into 6 groups and were treated with ketamine or thiopental. The plasma cortisol concentrations were determined before and after the treatment. The concentrations prior to the induction of anesthesia were 2.23 +/- 0.44 micrograms/dl (mean +/- SD) in pups (2 to 3 months old), 4.35 +/- 2.04 micrograms/dl in adults (2 years old), and 3.40 +/- 1.25 micrograms/dl in aged dogs (8 to 10 years old). This result indicated the following order of plasma cortisol levels in dogs: pups less than aged dogs less than adults. The plasma cortisol concentrations after ketamine administration tended to increase. This suggested that the adrenocortical function in the dog was stimulated by ketamine. In the ketamine treated dogs, significant differences were demonstrated among the age groups. Namely, a significantly lower response was noted in pups compared to adults or aged dogs (p less than 0.001). On the other hand, the plasma cortisol levels after the thiopental treatment showed a temporary slight increase in aged dogs but tended to decrease in pups and adults. Thiopental was found to have a suppressive effect on the adrenocortical function in dogs in contrast to ketamine.

Adrenal Cortex↗
PubMed1989

Pharmacokinetics of quinidine sulfate in dairy cattle.

Pharmacokinetic profile and therapeutic range of plasma quinidine concentration were determined in dairy Holstein cows. Plasma half-life of intravenous quinidine was 1.28 +/- 0.492 (0.41-1.65) hr. The pattern of plasma quinidine transition after oral administration varied greatly among individuals. Total body clearance was 58.7 +/- 24.49 ml/min/kg, although renal quinidine clearance was 0.76 +/- 0.441 ml/min/kg. Therefore, the involvement of some extrarenal organ as the main site of excretion was suspected. Seven cows, diagnosed as atrial fibrillation or ventricular premature contraction, were orally administered with quinidine at various dosages. They showed plasma concentration of 2.3 +/- 1.59 mg/l when therapeutic effect was observed. Clinical signs of intoxication were observed at plasma quinidine concentrations over 10 mg/l. These results suggest the difficulty with the maintenance of effective plasma quinidine concentration by an oral or a single intravenous administration, and thus it is concluded that use of quinidine for treatment arrhythmic cows must be carefully done in order to avoid possible intoxication.

Administration, Oral↗
PubMed1988

Inhibition and resumption of processing of the staphylokinase in some Escherichia coli prlA suppressor mutants.

Escherichia coli strains carrying certain prlA mutations (prlA4 and prlA401) could not support the processing and export of staphylokinase, resulting in the accumulation of the precursor form under high-level synthesis conditions. In order to clarify the cause of the defect in the structure of staphylokinase, we constructed signal peptide mutations of sak which suppressed the processing defect in the prlA4 cells by site-directed mutagenesis. The processing defect was suppressed when glycine or asparagine was introduced in place of the serine residue at position 17 from the amino terminus of the signal peptide. Substitutions of glycine for the leucine residue at position 15 and for the serine residue at position 19 were also effective. Other mutations we constructed had no suppression activity. Taking account of the correlation between the suppression activity and the parameter value of each substituted amino acid for the beta-turn probability, we predict that the staphylokinase signal peptide requires a more bending structure at the end of the hydrophobic core to act efficiently in the prlA4 cells than in the prl+ cells and that a function of the PrlA protein necessary to recognize the staphylokinase signal peptide has become deficient through the prlA4 mutation.

Amino Acid Sequence↗
PubMed1988

Contrasting actions of staurosporine, a protein kinase C inhibitor, on human neutrophils and primary mouse epidermal cells.

Staurosporine, a recently described microbial alkaloid, is uniquely potent as an inhibitor of protein kinase C in vitro, being active at nM concentrations rather than the microM concentrations typical of other inhibitor classes. Like these other inhibitors, however, staurosporine exhibits only limited selectivity among different protein kinases. We report here that, in intact human neutrophils, nM concentrations of staurosporine blocked the action of the phorbol ester tumor promoters. In mouse primary epidermal cells, on the other hand, staurosporine failed to block the effects of phorbol 12,13-dibutyrate on epidermal growth factor binding and on induction of ornithine decarboxylase and epidermal transglutaminase. Unexpectedly, staurosporine induced morphological changes in keratinocytes to a dendritic shape resembling that induced by the phorbol esters. It also induced epidermal transglutaminase and cornified envelope production, markers of the differentiative pathway in the epidermal cells. We conclude that the effectiveness of staurosporine as a protein kinase C inhibitor in intact cells may depend markedly on the cell system. Other actions of staurosporine may predominate, and, in keratinocytes, its activity is suggestive of a tumor promoter rather than of an inhibitor of tumor promotion.

Alkaloids↗