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Biomedical subjects

T Ohta

Publications and source records attributed to T Ohta.

At least 397 records · Page 22Linked to original sources
PubMed1998

The leuO gene product has a latent ability to relieve bgl silencing in Escherichia coli.

The Escherichia coli bgl operon is of interest, since its expression is silent (phenotypically Bgl-), at least under standard laboratory conditions. Here we attempted to identify a trans-acting factor(s) that is presumably relevant to the regulation of bgl by a random insertion mutagenesis with mini-Tn10. These collected mutations, conferring the phenotype of Bgl+, were localized in three loci on the genetic map, two of which appeared to be hns and bglJ, which were previously implicated as the factors affecting the Bgl phenotype. The other locus at 1 to 2 min on the genetic map appeared to be a new one. In this case, the insertion mutation was found to be just in front of the leuO gene encoding a putative LysR-like DNA-binding protein. Genetic analyses revealed that overproduction of LeuO in the wild-type cells causes the phenotype of Bgl+. A leuO deletion mutant was also characterized in terms of expression of bgl. From these results, the possible function of LeuO in bgl expression will be discussed from an evolutionary and/or ecological point of view.

Bacterial Proteins↗
PubMed1998

DNA supercoiling factor localizes to puffs on polytene chromosomes in Drosophila melanogaster.

DNA supercoiling factor (SCF) was first identified in silkworm as a protein that generates negative supercoils in DNA in conjunction with eukaryotic topoisomerase II. To analyze the in vivo role of the factor, we cloned a cDNA encoding Drosophila melanogaster SCF. Northern analysis revealed 1.6- and 1.8-kb mRNAs throughout development. The longer mRNA contains an open reading frame that shares homology with mouse reticulocalbin whereas the shorter one encodes a truncated version lacking the N-terminal signal peptide-like sequence. An antibody against SCF detected a 45-kDa protein in the cytoplasmic fraction and a 30-kDa protein in the nuclear fraction of embryonic extracts. Immunoprecipitation suggests that the 30-kDa protein interacts with topoisomerase II in the nucleus, and hence that it is a functional form of SCF. Immunostaining of blastoderm embryos showed that SCF is present in nuclei during interphase but is excluded from mitotic chromosomes. In larvae, the antibody stained the nuclei of several tissues including a posterior part of the salivary gland. This latter staining was associated with natural or ecdysteroid-induced puffs on polytene chromosomes. Upon heat treatment of larvae, the staining on the endogenous puffs disappeared, and strong staining appeared on heat shock puffs. These results implicate SCF in gene expression.

Amino Acid Sequence↗
PubMed1998

Serum 1alpha,25-dihydroxyvitamin D3 accumulates into the fracture callus during rat femoral fracture healing.

1,25-dihydroxyvitamin D3 (1,25(OH)2D3) is thought to be an important systemic factor in the fracture repair process, but the mechanism of action of 1,25(OH)2D3 has not been clearly defined. In this study, the role of 1,25(OH)2D3 in the fracture repair process was analyzed in a rat closed femoral fracture model. The plasma concentration of 1,25(OH)2D3 rapidly decreased on day 3 and continued to decrease to 10 days after fracture. We assessed whether this decrease was based on the accelerated degradation or retardation of the synthesis rate of 1,25(OH)2D3, from 25(OH)D3. After radiolabeled 3H-1,25(OH)2D3 or 3H-25(OH)D3 was injected i.v. into fractured or control (unfractured) rats, the concentrations of 25(OH)D3 and 1,25(OH)2D3 metabolites were measured by HPLC. The plasma concentrations of these radiolabeled metabolites in fractured group were similar to those in control rats early after operation. However, radioactivity in the femurs of fractured rats was higher than that of the control group. Furthermore, the radioactivity was concentrated in the callus of the fractured group analyzed by autoradiography. 1,25(OH)2D3 receptor gene expression was detected early after fracture and, additionally, both in the soft and hard callus on days 7 and 13 after fracture. These results showed that the rapid disappearance of 1,25(OH)2D3 in the early stages after fracture was not due to either increased degradation or decreased synthesis of 1,25(OH)2D3, but rather to increased consumption. Further, these results suggest the possibility that plasma 1,25(OH)2D3 becomes localized in the callus and may regulate cellular events in the process of fracture healing.

Animals↗
PubMed1998

Electron microscopic observations on sperm penetration in cytochalasin-treated eggs of the rose bitterling.

The effects of cytochalasin B (CB), which acts on microfilaments, on sperm penetration into eggs of a teleost fish were investigated ultrastructurally. Eggs from the rose bitterling, Rhodeus ocellatus ocellatus, were pre-treated in physiological saline containing CB and inseminated in water also containing CB. Microvilli at the sperm entry site (SES) under the micropyle disappeared or shortened in length following CB treatment. However, a spermatozoon attached to and fused with the SES of CB-treated eggs. The spermatozoon present in a swollen mass (SM) remained at the egg surface even after membrane fusion and did not enter the cortex. It was unclear whether or not sperm movement from the cortex to the inner cytoplasm is CB-sensitive. The SM formed and plugged the micropyle. CB did not inhibit cortical alveolus breakdown. Based on the present experiments with fish eggs, it is concluded that CB inhibits sperm movement from the egg surface to the cortex, but not sperm attachment (binding), membrane fusion and SM formation during the process of sperm penetration.

Animals↗
PubMed1998

Action properties of HYI killer toxin from Williopsis saturnus var. saturnus, and antibiotics, aculeacin A and papulacandin B.

The mechanism of the killing and cytocidal effects produced by HYI toxin from Williopsis saturnus var. saturnus, and by the amphiphilic antibiotics aculeacin A and papulacandin B on yeast Saccharomyces bayanus cells was studied. When the yeast cells were treated with these molecules, a discharge of cell materials at the budding position was observed by phase-contrast and scanning electron microscopy. The cytocidal effect of these molecules was most pronounced when the cells were in the logarithmic growth phase. Washing the HYI toxin incubation mixture completely eliminated the killing activity, but in the case of the antibiotics, it only partially reduced the cytocidal activity. Full recovery of the killing activity in the supernatant of the washing solution was observed after HYI toxin incubation, but in the case of the antibiotics, the recovery of cytocidal activity was time-dependent. The activity of membrane beta-1,3-glucan synthase was potently inhibited by HYI toxin, and the concentration of this enzyme in the budding tip was observed. These results suggest that HYI toxin exerts a cytocidal effect on the budding of sensitive yeast cells by inhibiting cell wall synthesis. This mechanism is similar to that of the HM-1 toxin of W. saturnus var. mrakii, and to aculeacin A and papulacandin B, although there are some differences from that of HYI toxin.

Aminoglycosides↗
PubMed1998

Anandamide, an endogenous cannabinoid receptor ligand, also interacts with 5-hydroxytryptamine (5-HT) receptor.

Interactions of anandamide (N-arachidonylethanolamide), an endogenous compound for cannabinoid receptors, with the receptors for 5-hydroxytryptamine (5-HT), benzodiazepine, and gamma-aminobutyric acid(A) (GABA[A]) receptors in bovine synaptic membrane were examined. Anandamide decreased the 5-HT receptor bindings at concentrations of 1-100 microM, although it did not cause any change in benzodiazepine or GABA(A) receptor bindings. A high concentration of anandamide, 100 microM, significantly decrease both [3H]5-HT and [3H]ketanserin bindings. The present study revealed that the pharmacological activity of anandamide might be partially mediated through the 5-HT receptor.

Animals↗
PubMed1998

Two types of relaxation-mediating P2 receptors in rat gastric circular muscle.

Effects of purinoceptor antagonists on the relaxant responses to adenine nucleotides were examined to characterize the subtypes of P2-receptor in rat gastric circular muscle. In tissues contracted by acetylcholine, a P2-receptor antagonist, suramin (100 microM), inhibited the relaxant responses to ATP, adenosine 5'-O-(2-thiodiphosphate) (ADPbetaS) and alpha,beta-methylene ATP but not that to adenosine, while a P1-receptor antagonist, 8-phenyltheophylline (3 microM) did vice versa. The inhibitory effect of suramin was more potent for the relaxant responses to alpha,beta-methylene ATP than those to ATP or ADPbetaS. Pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) (3-30 microM) and 4,4'-diisothiocyanatostilbene-2,2'-disulphonate (DIDS) (30 and 100 microM) inhibited the relaxation caused by alpha,beta-methylene ATP but not by ATP, ADPbetaS or adenosine. These results suggest that ATP and ADPbetaS cause relaxation via the classical P2Y receptors resistant to PPADS and DIDS. In addition, alpha,beta-methylene ATP causes relaxation via the distinct P2 receptors sensitive to PPADS and DIDS in rat gastric circular muscle.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1998

Effect of indigestible oligosaccharides on the hepatotoxic action of D-galactosamine in rats.

The effects of dietary oligosaccharides on the hepatotoxic action of D-galactosamine (GalN) were investigated in this study. Male Wistar rats fed with 20% casein diets containing 10% oligosaccharide or D-galactose (Gal) for 2 weeks were injected with GalN (1,900 mg/kg of body weight), and the plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities and the hepatic glycogen concentration were examined 20 hours after the injection. The plasma AST and ALT activities in experiment 1 for the Gal + neomycin (NEO) group were significantly lower than those for the control (C), NEO, raffinose (RAF) + NEO and galacto-oligosaccharide (GA-LO) + NEO groups. In experiment 2, these activities were significantly lower in the Gal, Gal + NEO and RAF groups than in the RAF + NEO group when the groups were treated with GalN. On the other hand, in respect of the hepatic glycogen concentration in experiment 1, that of the Gal + NEO group was higher than that of the C, NEO, RAF + NEO or GALO + NEO groups. In experiment 2, this parameter was significantly higher in the Gal, Gal + NEO and RAF groups than in the RAF + NEO group after the GalN treatment. As a result, it is suggested that the GalN-hepatitis-suppressive effects of indigestible oligosaccharides such as RAF or GALO is mediated by the action of intestinal bacteria.

Alanine Transaminase↗
PubMed1998

P1 specificity of aqualysin I (a subtilisin-type serine protease) from Thermus aquaticus YT-1, using P1-substituted derivatives of Streptomyces subtilisin inhibitor.

Aqualysin I is an alkaline serine protease isolated from Thermus aquaticus YT-1, an extreme thermophile. We have measured the P1-specificity of aqualysin I, using wild-type and five P1-substituted derivatives of Streptomyces subtilisin inhibitor (SSI). SSIs efficiently inhibited the activity of aqualysin I, with low substrate specificity. Charge and hydrophobicity of side chain of the P1 amino acid residue showed no significant effect to the P1-specificity of this enzyme.

Bacterial Proteins↗
PubMed1998

Nursing practitioners' perception of inpatients' anxiety, self-esteem, purpose-in-life and health locus of control.

This study explored how nursing practitioners perceived inpatients' anxiety, self-esteem, purpose-in-life and multidimensional health locus of control. Seventy-three nurses, 60 third-year and 70 first-year nursing students, and 61 control students not majoring in nursing science estimated how inpatients rated these four psychological states. Their ratings were compared with those given by 121 inpatients. Findings showed that the nursing practitioners, as well as the control participants, overestimated inpatients' anxiety, while they underestimated their self-esteem and purpose-in-life. The inpatients' scores for internal locus of control were greater than their scores for the two types of external locus of control (powerful others and chance), and were also greater than the scores given by the nursing practitioners in estimating the patients' perception of internal locus of control. The findings indicate that inpatients have a more positive attitude toward themselves and their own lives, and hence much better mental health, than the nursing practitioners estimate they do.

Adult↗
PubMed1998

Cavernous angioma associated with venous angioma--two case reports.

A 17-year-old male and a 28-year-old female presented with cavernous angioma and venous angioma colocated in the same region, and manifesting as convulsions. The cavernous angiomas were extirpated without damage to the venous angioma. No postoperative neurological deficits were observed. The patients have been free of convulsions without anticonvulsant medication for 2 years. Early extirpation of cavernous angioma with presentation of venous angioma is recommended, preferably before bleeding occurs.

Adolescent↗
PubMed1998

Dietary linoleic acid alters alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD), a key enzyme of niacin synthesis from tryptophan, in the process of protein expression in rat liver.

alpha-Amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD) [EC 4.1.1.45] is a key enzyme of niacin synthesis from tryptophan. In this study, we examined whether dietary linoleic acid alters the protein expression of ACMSD in rat liver. Antibody against rat liver ACMSD was prepared by injecting mice with the purified enzyme. With the use of this polyclonal antibody and analysis by two-dimensional electrophoresis, we studied the mechanism by which the level of liver ACMSD activity was varied in rats fed a linoleic acid diet. In the rats fed a dietary linoleic acid (L), ACMSD protein levels in the liver were strongly suppressed as compared with the rats fed a fat-free diet (FF). These results suggest that the expression level of ACMSD might be modulated by linoleic acid or their metabolites.

Animals↗
PubMed1998

Cationic trypsinogen produced by human pancreatic ductal cancer has the characteristics of spontaneous activation and gelatinolytic activity in the presence of proton.

We examined whether human pancreatic ductal cancer cells express and secrete pancreatic cationic trypsinogen in vitro which can be spontaneously converted into active trypsin at acidic pH (pH 4.5-5. 5), in contrast to anionic trypsinogen. Cationic trypsinogen expression at the mRNA level was observed in differentiated Capan-1 and BxPC-3 cell lines. However, expression was not detected in either poorly-differentiated Panc-1 or undifferentiated MIAPaCa-2 cell line. The gelatinolytic activity of the activated form of trypsinogen in each conditioned medium in the presence of enterokinase (1.0 microg/ml) (a band with a molecular weight of approximately 23 kDa) corresponded well to the level of cationic trypsinogen mRNA. The spontaneous activation of trypsinogen also was observed by gelatin zymography of the acid-loaded conditioned medium (pH 5.5). These findings suggest that trypsinogen produced by human pancreatic ductal cancer has the characteristics of spontaneous activation and gelatinolytic activity in the presence of proton.

Culture Media, Conditioned↗
PubMed1998

Cell proliferative activity in intraductal papillary-mucinous neoplasms and invasive ductal adenocarcinomas of the pancreas: an immunohistochemical study.

OBJECTIVE: To evaluate cell proliferative activity and expression of cytokeratins (CKs) and epithelial membrane antigen (EMA) in intraductal papillary-mucinous neoplasm of the pancreas (IPNP). METHODS: We examined cell proliferative activity in normal pancreatic ducts, IPNP, and invasive ductal adenocarcinoma of the pancreas by immunohistochemistry for proliferating cell nuclear antigen (PCNA) and Ki67 antigen. Expression of CKs and EMA was also examined immunohistochemically. RESULTS: In normal pancreas (n = 5), PCNA- or Ki67-positive ductal epithelia were not found. Cytokeratins (polyclonal, CAM5.2, CK-7, CK-8, CK-18, and CK-19) were expressed in the ducts and ductules but not in the acinus, and EMA expression was noted in the acinus but rarely in the ducts. In IPNP (n = 9) and invasive ductal adenocarcinoma (n = 6) of the pancreas, the overall PCNA-labeling index (PCNA-LI) was 3.2 +/- 4.1 and 16.0 +/- 7.2, respectively, and overall Ki67-LI was 2.2 +/- 2.6 and 14.5 +/- 6.3, respectively. In IPNP, the PCNA-LI and Ki67-LI were low in adenoma areas (PCNA-LI = 0.9 +/- 0.7), intermediate in dysplastic areas (PCNA-LI = 3.7 +/- 2.4), and rather high in carcinoma in situ areas (PCNA-LI = 11.5 +/- 8.4). Both CKs and EMA were noted in tumor cells. CONCLUSIONS: The data suggest that cell proliferative activity is low in IPNP compared to invasive ductal adenocarcinoma, that cell proliferative activity increases with the grade of cell atypia in IPNP, and that CK expression is not changed during the neoplastic change, but EMA is newly expressed or overexpressed during the neoplastic change.

Aged↗
PubMed1998

[Polysomnography and other methods for the assessment of sleep disorders].

Polysomnography is an essential tool in the assessment of sleep disorders. However, PSG alone not always sufficient to evaluate various sleep disorders patients. For instance, in patients with suspected inadequate sleep hygiene, sleep logs or questionnaires on sleep habits may, be helpful in making the diagnosis. Patients who complain of excessive daytime sleepiness as a result of insomnia should be evaluated with the Epworth sleepiness scale and/or polysomnographic nap studies such as the multiple sleep latency test. In patients with suspected circadian rhythm sleep disorder, continuous temperature monitoring together with sleep log and actigraphy may establish the phase relationship between sleep-wake rhythms and other biological rhythms. Because polysomnographic measurements are cumbersome and expensive, it is necessary to select the suitable methods for the assessment of sleep disorders by the careful examination of the patients' complain.

Circadian Rhythm↗
PubMed1998

Chylous reflux into the lower limb with septic shock successfully treated by resection of the retroperitoneal megalymphatics.

A 15-year-old boy with primary chylous reflux into the left lower limb with septic shock was successfully treated by en bloc resection and ligation of the retroperitoneal megalymphatics. The episode of chyle discharge from the lower limb and/or genitalia and the presence of small vesicles of the skin may be an important sign in diagnosing chylous reflux. Surgical interruption of the chylous reflux and reduction of girth may be needed.

Adolescent↗
PubMed1998

[Peripheral blood stem cell transplants: clinical considerations and observations in practice in a general hospital].

Of 36 patients with malignant tumors who had been subjected to peripheral blood stem cell harvests (PBSCHs), 22 had undergone peripheral blood stem cell transplants (PBSCTs) since 1993. Flow cytometry recorded higher CD34+ cell yields in the PBSCHs of those patients with high white blood cell (WBC) counts as well as those who had been under intensive chemotherapy. Also, higher CD34+ cell yields were recorded in patients whose peripheral blood WBCs recovered more rapidly from their nadir state. WBC counts recovered rapidly in patients who received transfusions of at least 2.0 x 10(6) CD34+ cells/kg. However, patients with acute non-lymphocytic leukemia (ANLL) demonstrated a delayed recovery in their platelet counts following PBSCT. The mean disease-free survival rate and mean disease-free period were 60% and 12.8 months for the 5 patients with ANLL; and 100% and 11.3 months for the 4 patients with acute lymphocytic leukemia. These findings suggest PBSCT is a safe and effective treatment for patients with malignant tumors following high-dose chemotherapy, and can be performed in a private general hospital.

Adolescent↗