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Biomedical subjects

Y Murakami

Publications and source records attributed to Y Murakami.

At least 829 records · Page 46Linked to original sources
PubMed1988

Requirement of the Escherichia coli dnaA gene function for integrative suppression of dnaA mutations by plasmid R 100-1.

The phenotype of Escherichia coli dnaA missense and nonsense mutations was integratively suppressed by plasmid R100-1. The suppressed strains, however, could not survive when the dnaA function was totally inactivated. This was demonstrated by the inability of replacing the dnaA allele in the suppressed strain by a dnaA::Tn10 insertion using phage P1-mediated transduction. When the intact dnaA+ allele was additionally supplied by a specialized transducing phage, lambda imm21 dnaA+, which integrated at the att lambda site on the E. coli chromosome, then the dnaA::Tn10 insertion, together with a delta oriC deletion, were able to be introduced into the suppressed strain. Thus, the mechanisms of dnaA function for oriC and for the replication origin of R100-1 may not be quite the same.

Bacterial Proteins↗
PubMed1988

Difference in growth behavior of human, swine, equine, and avian influenza viruses at a high temperature.

Growth characteristics of a wide range of influenza A viruses from different mammals and bird species were examined in an established line of canine kidney (MDCK) cells at an ordinary (37 degrees C) and a high temperature (42 degrees C). Although all viruses employed in the present study possessed a capability of replicating at 37 degrees C, virus growth at 42 degrees C showed considerable variation and reflected differences in the natural hosts of the isolates. All reference strains and isolates from bird species grew well in the MDCK cells maintained at 42 degrees C, but human viruses did not, showing an asymmetrical growth behavior. In contrast to this, growth of swine and equine viruses showed growth characteristics intermediate between human and avian viruses. Of the two swine viruses examined, replication of one strain occurred equally well at both temperatures and another failed to grow at 42 degrees C. Similarly, two of the three equine viruses tested belonging to H3N8 antigenic subtypes grew at 42 degrees C. However, the results obtained from comparison of plaque sizes and growth curves indicated that the replication of the above swine and equine viruses was restricted under a stringent temperature when compared to avian viruses. The detailed analysis of cloned viruses revealed that some of the swine and equine viruses contained two variants which are readily distinguished by growth behavior at 42 degrees C. Genome analysis of parental and virus clones by oligonucleotide mapping and migration profiles of RNA segments did not detect any differences among the above variants exhibiting the asymmetrical growth characteristics at 42 degrees C.

Animals↗
PubMed1988

Inhibition of transforming activity of tyrosine kinase oncogenes by herbimycin A.

We studied the effectiveness of herbimycin A, an inhibitor of the function of the temperature-sensitive src oncogene, to reverse the morphologies of chicken and mammalian cells transformed by various oncogenes. It was found that the antibiotic was effective against the cells transformed by tyrosine kinase oncogenes src, yes, fps, ros, abl, erbB, but did not reverse the transformed morphologies induced by oncogenes raf, ras, and myc. Moreover, decreases in phosphotyrosine content of the total cellular proteins and in 36K protein phosphorylation by herbimycin treatment supported the selective inhibition of the antibiotic on the transforming activity of tyrosine kinase oncogenes.

Animals↗
PubMed1988

Two-step purification of mouse kidney ornithine decarboxylase.

We developed a simple two-step purification procedure for ornithine decarboxylase (ODC, EC 4.1.1.17), consisting of DEAE-Cellulofine chromatography and affinity chromatography on a HO-101 monoclonal anti-rat liver ODC antibody-Affi-Gel 10 column. By this method, ODC was purified 1700-fold to homogeneity with about 80% yield from the kidney of ICR mice treated with testosterone enanthate. The final specific activity range between 1.0 x 10(6)-1.4 x 10(6) nmol/h.mg protein. On SDS-polyacrylamide gel electrophoretic analysis, the final preparations gave a major protein band of Mr 54,000 and a minor band of Mr 51,000. Although relative staining intensity of the two bands varied depending on preparations, both bands could be stained by immunoblotting and labeled by a preincubation with [14C]difluoromethylornithine (DFMO). On Oudin double diffusion immunoanalysis, a single fused precipitin line was formed between purified anti-mouse kidney ODC IgG and both the purified enzyme and crude mouse kidney extract. In contradiction with earlier reports, no significant difference was observed between mouse kidney ODC and rat liver ODC in either final specific activity or specific binding of labeled DFMO.

Animals↗
PubMed1988

Relationship between enzyme activities involved in oxygen metabolism and oxygen tolerance in black-pigmented Bacteroides.

In this study, the relationship between enzyme activities involved in oxygen metabolism and the degrees of oxygen tolerance in black-pigmented Bacteroides was investigated. All strains of Bacteroides tested possessed the activities of NADH oxidase and superoxide dismutase, whereas the activities of catalase and peroxidases were not detected in the cell-free extracts. There were relatively high correlations between oxygen tolerance and activity of either NADH oxidase or superoxide dismutase. The activity of superoxide dismutase showed a higher correlation with oxygen tolerance than with that of NADH oxidase. Among the species tested, Bacteroides gingivalis showed the highest activities of both the enzymes and was the most tolerant in the presence of oxygen. Furthermore, the activities of these two enzymes increased during aeration of the oxygen-tolerant strain Bacteroides gingivalis 381, but not in the oxygen-sensitive strain Bacteroides denticola ATCC 33185. These results suggest that superoxide dismutase and NADH oxidase might be important for protection of black-pigmented Bacteroides against the toxic effect of oxygen.

Bacteroides↗
PubMed1988

Stimulation of growth hormone secretion by central administration of atrial natriuretic polypeptide in the rat.

Intracerebroventricular (icv) injection of alpha-human atrial natriuretic polypeptide (alpha hANP) or alpha-rat ANP (0.6 and 3 nmol/rat) elicited an increase in plasma GH levels both in conscious freely moving rats and in urethane-anesthetized rats when given at the trough of spontaneous GH secretion. Antiserum specific for rat GRF did not affect the plasma GH increase induced by icv injection of alpha hANP. Intracerebroventricular injection of alpha ANP (3 nmol/rat) failed to stimulate GH secretion in conscious rats pretreated with cysteamine (30 mg/100 g BW, sc), a depletor of somatostatin (SRIF), and in conscious rats during constant iv infusion of SRIF (55 ng/ml). GH release induced by iv injection of synthetic rat GRF (200 ng/100 g BW) was exaggerated by alpha hANP (3 nmol/rat, icv) in conscious rats. These results suggest that central ANP stimulates pituitary GH secretion possibly by inhibiting SRIF release from the hypothalamus in the rat.

Animals↗
PubMed1988

Urinary growth hormone levels measured by ultrasensitive enzyme immunoassay in patients with renal insufficiency.

An ultrasensitive enzyme immunoassay was used to measure urinary GH levels in patients with renal insufficiency and normal subjects. Urinary GH excretion varied widely, but was significantly higher (P less than 0.01) in patients with renal insufficiency (median, 339; range, 2-17,000 ng/day) than in normal subjects (5.4; 1.2-15 ng/day). Urinary GH excretion correlated positively with urinary beta 2-microglobulin excretion (r = 0.79; P less than 0.001) and negatively with creatinine clearance (r = -0.83; P less than 0.001). Gel chromatography of urine from patients with renal insufficiency revealed a major peak of urinary GH corresponding to a mol wt of 22K, that of pituitary GH. These findings suggest that the kidneys play an important role in the catabolism of GH and that urinary GH may reflect, at least in part, renal function as well as hypothalamo-pituitary function.

Adolescent↗
PubMed1988

Urinary growth hormone (GH) measurements are useful for evaluating endogenous GH secretion.

Daily (24-h) urinary GH excretion was measured using a highly sensitive sandwich enzyme immunoassay in 10 normal adults, 6 patients with hypopituitarism, 25 normal but short children who had normal plasma GH responses (peak plasma GH level, greater than 10 micrograms/L) to provocative tests, and 8 patients with acromegaly. The mean urinary GH values in the normal adults, patients with acromegaly, and patients with hypopituitarism were 13.8 +/- 4.0 (+/- SE) and 431.1 +/- 149.1 ng/g creatinine (Cr) (1.56 +/- 0.45 and 48.77 +/- 16.87 ng/mmol Cr) and undetectable, respectively; these mean values were significantly different from each other. In the normal but short children the urinary values ranged from undetectable to 55.8 ng/g Cr (6.31 ng/mmol Cr). All of the normal but short children and 4 patients with hypopituitarism participated in a 24-h endogenous GH secretion study. The urinary GH values correlated significantly with the mean 24-h plasma GH concentrations as an index of endogenous GH secretion (r = 0.81; P less than 0.001) and plasma somatomedin-C levels (r = 0.67; P less than 0.001), respectively. In 6 patients with acromegaly whose plasma GH levels were constant throughout a 4-h period, the urinary GH values also significantly correlated with the mean plasma GH levels (r = 0.95; P less than 0.01). These data indicate that urinary GH measurements reflect endogenous GH secretion and that measurement of urinary GH excretion is a useful, simple, and practical method for evaluating endogenous GH secretion.

Acromegaly↗
PubMed1988

Left ventricular end-systolic wall stress--dimension relationship in unanesthetized dogs with perinephritic hypertension.

To study myocardial contractility in hypertensive hearts with normal wall motion, we examined left ventricular end-systolic wall stress-dimension relationships (ESWDR) during a baseline period (CS: control stage) and in the eighth week after induction of systemic hypertension by Page's method (HS: hypertensive stage) in unanesthetized dogs. The mean aortic blood pressure increased from 94 +/- 11 to 142 +/- 26 mmHg (p less than 0.01). The end-diastolic left ventricular posterior wall thickness increased significantly during the HS (9.4 +/- 1.3 vs 7.3 +/- 1.3 mm; HS vs CS), and its dimension was significantly (p less than 0.05) smaller than it was during the CS (37.0 +/- 4.2 vs 39.9 +/- 4.6 mm; HS vs CS). There were no significant differences between the 2 stages in left ventricular fractional shortening (31.9 +/- 5.0 vs 32.6 +/- 2.8; HS vs CS), in end-systolic meridional left ventricular wall stress (75.3 +/- 10.8 vs 68.3 +/- 15.6 10(3) dynes/cm2; HS vs CS), or in the ESWDR slopes (98.6 +/- 17.7 vs 94.0 +/- 19.7; HS vs CS). The ESWDR dimension intercepts significantly decreased from 2.0 +/- 0.3 to 1.8 +/- 0.3 cm during the HS; that is, the relationship shifted to the left with no significant change in the slope. At autopsy, the ratio of left ventricular weight to body weight of the hypertensive dogs was significantly (p less than 0.01) greater than that of sham-operated control dogs (6.0 +/- 0.9 vs 4.3 +/- 0.5 g/kg).(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗
PubMed1988

Ventricular fibrillation threshold measured by continuous 50 cps stimulation for the evaluation of the antifibrillatory effect of the drugs.

The role of electrophysiologic parameters on the induction of ventricular fibrillation (VF) by continuous 50 cycle per second (cps) electrical stimulation was studied in 21 open chest dogs. The current strength of the 50 cps stimulation required to induce VF when applied to the ventricle for 2 seconds was defined as the ventricular fibrillation threshold (VFT). The intravenous injection of antiarrhythmic drugs raised the VFT in a dose dependent manner. The changes in VFT were associated with a rise in excitation threshold. The slopes of the regression equations relating the excitation threshold to VFT were almost identical, that is, 2.8 with lidocaine, 3.4 with procainamide and 3.2 with disopyramide. Prolongation of refractory period increased the cycle length of ventricular excitations just prior to VF but was not correlated with the changes in VF. Localized myocardial ischemia induced by coronary ligation also resulted in the elevation of VFT. The slope of the regression equation between excitation threshold and VFT was 1.9 which was slightly lower than that observed at the administration of the drugs. The fact that the VFT was mainly attributed to the changes in excitation threshold at the site where the test stimulus was applied would limit the usefulness of the 50 cps continuous stimulation method for the evaluation of vulnerability to VF.

Animals↗
PubMed1988

Sensitive sandwich enzyme immunoassay of human growth hormone (hGH) in serum and urine using monoclonal antibody-coated polystyrene balls.

A sensitive sandwich enzyme immunoassay for human growth hormone (hGH) using monoclonal antibody is described. A monoclonal anti-hGH IgG-coated polystyrene ball was incubated with hGH and subsequently with affinity-purified rabbit anti-hGH Fab'-horseradish peroxidase conjugate. Peroxidase activity bound to the polystyrene ball was assayed by fluorimetry using 3-(4-hydroxyphenyl) propionic acid as a substrate. The detection limits of hGH in serum and urine were 1.5 ng/l using 20 microliters of serum and 0.2 ng/l using 0.15 ml of urine, respectively. The specificity and assay precision were satisfactory. hGH levels in serum and urine determined by the present sandwich enzyme immunoassay using monoclonal anti-hGH IgG-coated polystyrene balls were well correlated to those determined by the previous sandwich enzyme immunoassay using rabbit anti-hGH IgG-coated polystyrene balls. Levels of hGH in urine collected as first morning voids from healthy subjects aged 19-28 yr were 6.4 +/- 3.2 (SD) ng/g creatinine. However, the present assay gave lower hGH levels than the previous assay. This was at least partly explained by the fact that hGH in urine was less efficiently bound to monoclonal anti-hGH IgG-polystyrene balls than standard hGH, while the binding of hGH in urine and standard hGH to rabbit anti-hGH IgG-coated polystyrene balls was equally efficient. In addition, gel filtration showed that 22K hGH, a major component, in urine was less efficiently bound to monoclonal anti-hGH IgG-coated polystyrene balls than standard 22K hGH. The nature of hGH in serum and urine remains to be investigated.

Adult↗
PubMed1988

[Two cases of acute idiopathic subdural hematoma with delayed intracranial hypertension].

Two cases of acute idiopathic subdural hematoma with delayed intracranial hypertension were presented. The first case was a 68-year-old man admitted for vomiting following headache for eight days. There was no history of head trauma. A CT scan revealed a high-density mass that had a concave inner margin in the left temporo-parietal region with a slight midline shift. No vascular lesion was noted on the angiogram. The consciousness of the patient deteriorated suddenly on the 12th day. An operation was performed because of a marked midline shift on the CT. At operation, a subdural clot was removed. The postoperative recovery was good. The patient was discharged 7 days later without any neurological deficit. The second case was a 69-year-old man who was admitted with sudden onset of headache. There was no history of head trauma. A CT scan showed a high density mass in the right temporoparietal subdural space with a slight midline shift. The consciousness of the patient deteriorated suddenly on the 15th day. An operation was performed because of a marked midline shift on the CT. At operation, a subdural hematoma was removed. Two days later, suddenly his consciousness deteriorated. A CT scan showed his severe brain edema with a marked midline shift without increased hematoma. External decompression was performed immediately. The postoperative recovery was very good and 40 days after the second operation, the patient was discharged with no neurological deficit. The delayed intracranial hypertension appeared in these two cases about 10 days after the initial symptom. Two kinds of mechanisms are suspected: 1) swelling of the hematoma because of the adsorption of cerebrospinal fluid, 2) the occurrence of secondary brain edema. From our experience, a repeated CT scan is necessary for 2 to 3 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗