Search PubMed⌕ Search

Biomedical subjects

H Tamura

Publications and source records attributed to H Tamura.

At least 253 records · Page 14Linked to original sources
PubMed1994

[Therapeutic effectiveness of prednisolone in Mycoplasma pulmonis-infected pneumonia in mice].

The present investigation was designed to analyze the therapeutic efficacy of prednisolone in the development of pulmonary lesions in Mycoplasma pulmonis-infected mice. Mice were treated every day from day 3 to day 9 after M. pulmonis inoculation with minocycline (group M), prednisolone (group P), or with minocycline and prednisolone (group MP) and a control group was left untreated. Mice from each group were sacrificed at days 7, 14, and 21. The macroscopic lung lesion scores of group MP at days 7, 14, 21, and of group M at day 7 were significantly lower (p < 0.05) compared with the control group. Pathological findings in group M and MP showed reduction of the polymorphonuclear leukocyte response in the alveoli compared with the controls. However, infiltration of lymphocytes around the bronchioles and blood vessels of group M was not less than that in group MP. The titer of CF antibody in group MP was the lowest of the four groups. Among the four groups, M. pulmonis was cultured in the joints of group P. These results suggest that combination therapy with minocycline and prednisolone was effective because the mice of group MP had a more marked reduction of infiltration of lymphocytes around the bronchioles and blood vessels as compared with group M. Simultaneously, with prednisolone alone therapy, a risk of dissemination of the mycoplasma organism and diminution of antibody production were suggested.

Animals↗
PubMed1993

The role of acidic amino-acid residues in catalytic and adsorptive sites of Bacillus cereus sphingomyelinase.

By the modification of acidic amino-acid residues with Woodward's reagent K (N-ethyl-5-phenylisoxazolium-3'-sulfonate), the activity of sphingomyelinase of Bacillus cereus was decreased by 80-90%. Also, the reduction of Cys residues in the sphingomyelinase molecule by dithiothreitol caused a drastic decrease in enzymatic activity, whereas the sphingomyelinase activity was not affected by treatment with p-chloromercuribenzenesulfonic acid. Actually, no inactivation of sphingomyelinase activity was observed after selective modification of basic amino-acid residues such as Lys, His and Arg, and of the uncharged amino-acid residues Ser and Thr. The treatment of the sphingomyelinase molecule with Woodward's reagent K or dithiothreitol also brought about the inhibition of the specific adsorption of sphingomyelinase toward intact erythrocyte membranes. However, the extent of inhibition in the enzyme adsorption, 20-50%, was less than that observed in the sphingomyelinase activity. These results suggest that acidic amino-acid residues, such as Asp and Glu, in the sphingomyelinase molecule are involved in the catalytic sites and the adsorptive sites. Apparently, the disruption of disulfide linkage in the sphingomyelinase molecule by dithiothreitol destabilized its structure, resulting in a drastic decrease in sphingomyelin-hydrolyzing activity and specific adsorption of sphingomyelinase towards erythrocyte membranes.

Amino Acid Sequence↗
PubMed1993

A 60-kDa thymic epithelial cell surface protein as a potent molecule mediating the cellular interaction with immature T cells.

A unique 60-kDa surface protein expressed on the thymic epithelial cells was characterized as a potent molecule participating in the interaction between thymic stromal cells (TSC) and immature T cells. Previously, we reported an athymic mouse-derived T cell clone, N-9F, which proliferates on TSC. In the present study, we established a TSC clone, SL10.3, from a BALB/c mouse. SL10.3 has an epithelial cell nature and supports N-9F and fetal thymocytes growth in vitro. The two rat monoclonal antibodies, AS19 and AS32, directed to the SL10.3 cell surface inhibited N-9F and fetal thymocytes growth on SL10.3, suggesting that the reactive molecule may mediate the cellular interaction between TSC and immature T cells. Both antibodies are directed to the same 60-kDa protein with a pI point of 5.4, but to different epitopes on the protein. The 60-kDa protein is distributed on thymic epithelial cells, fibroblasts, and vascular endothelial cells, but not on the hematopoietic cells tested.

Animals↗
PubMed1993

Inhibition of cell growth by bafilomycin A1, a selective inhibitor of vacuolar H(+)-ATPase.

Bafilomycin A1, a potent selective inhibitor of vacuolar H(+)-ATPase, inhibited the growth of a variety of cultured cells dose-dependently, including golden hamster embryo and NIH-3T3 fibroblasts, whether or not they were transformed, and PC12 and HeLa cells. The concentration of bafilomycin A1 for 50% inhibition of cell growth ranged from 10 to 50 nM. The dose response was nearly parallel with that of the bafilomycin A1-induced lysosomal pH increase. The degree of pH increase for growth inhibition produced by bafilomycin A1 was similar to that produced by NH4Cl in which little difference was recognized in effect among cell types.

3T3 Cells↗
PubMed1993

Purification and cDNA cloning of bovine liver 5'-nucleotidase, a GPI-anchored protein, and its expression in COS cells.

A glycosylphosphatidylinositol (GPI)-anchored protein, 5'-nucleotidase [EC 3.1.3.5], was released from the membrane of bovine liver by use of phosphatidylinositol-specific phospholipase C (PI-PLC) of Bacillus thuringiensis and purified by several column chromatographies to a homogeneous state. The purified protein has an apparent molecular mass of 61 kDa, as estimated by SDS-polyacrylamide gel electrophoresis. From the partial amino acid sequence of a tryptic peptide, mixed oligonucleotides were synthesized and used to screen a lambda gt11 liver cDNA library, and one positive clone, pE1, was isolated. Since the insert of the clone lacked the NH2-terminal coding region, another lambda gt11 liver cDNA library was screened by using a synthetic probe corresponding to the 5' region of the insert of pE1. Three additional cDNA clones were obtained. Sequencing of these cDNAs revealed an open reading frame that encodes a 574-residue polypeptide with a calculated mass of 63,084 Da. The predicted structure showed two highly hydrophobic stretches at both ends of the protein, like those of rat and human 5'-nucleotidases. The NH2-terminal 26 residues comprise a signal peptide and the COOH-terminal hydrophobic stretch may serve as a signal for the posttranslational GPI modification. An expression vector of the cDNA, pSVNT, was constructed in a mammalian expression vector pSVL and the 5'-nucleotidase activity was transiently expressed in COS-1 cells. The expressed activity was about 8 times higher than the pSVL-transfected control activity. PI-PLC released 45% of the transiently expressed 5'-nucleotidase activity, indicating that the cDNA isolated here encodes this enzyme expressed as a GPI-anchored protein.

5'-Nucleotidase↗
PubMed1993

Activation of limulus coagulation factor G by several (1-->3)-beta-D-glucans: comparison of the potency of glucans with identical degree of polymerization but different conformations.

It has been demonstrated that both linear and branched (6-O-beta-D-glucosyl) (1-->3)-beta-D-glucans taking a single helical conformation are more effective than those taking a triple helical conformation for the activation of factor G from horseshoe crab amebocytes, as revealed by high-resolution solid-state 13C-NMR spectroscopy [Saitô, H. et al. (1991) Carbohydr. Res. 217, 181-190]. Annealing the linear glucan at 180 degrees C was essential to convert the conformation from the single helix to the triple helix. We found that heating of the glucan at such a high temperature resulted in depolymerization of the sample to molecular weight smaller than 10,000, which may influence the conformation and the above-mentioned biological activity. To eliminate ambiguity arising from the depolymerization of the glucan during annealing, we aimed to relate the biological activity to the conformation of samples whose chain lengths are identical, because the potency is known to depend on the molecular weight of the glucans. This molecular weight dependency of the potency, however, was found to be not the dominant factor, provided that the molecular weight is large enough to allow formation of the single helix conformation. Therefore, the single helical conformation of (1-->3)-beta-D-glucans is clearly demonstrated to be the dominant contributor to the activation of limulus coagulation factor G.

Animals↗
PubMed1993

Development of local horizontal interactions in cat visual cortex studied by cross-correlation analysis.

1. To explore the functional development of local horizontal interactions in the primary visual cortex, we carried out cross-correlation analysis of spike trains recorded simultaneously from a pair of neurons separated horizontally by < 1 mm, in kittens ranging in age postnatally from the second to ninth week. 2. Significantly correlated firings were found in 87 pairs of cells among 423 pairs analyzed, and 77 pairs of them were classified into three types on the basis of their functional implications: 1) excitatory interactions, 2) inhibitory interactions, and 3) common inputs to both neurons of the pair from other sources. 3. Common inputs and excitatory linkage were observed even in animals at the second postnatal week, whereas inhibitory linkage was not seen before the fourth week of age. The probability of observing common inputs and inhibitory linkage increased during development, whereas that of excitatory linkage tended to decrease after the sixth week of age. 4. Significant correlation was rarely seen in pairs with horizontal separation > 600 microns in the seventh to ninth week. In the fourth to sixth week of age, however, approximately 30% of the pairs with horizontal separation between 600 and 800 microns were significantly correlated. 5. Cells that were not sensitive for orientation or that lacked a visual response were observed mainly before the sixth week of age. These cells tended to receive excitatory effects from and share common inputs with other orientation-sensitive cells that were located within the horizontal distance of 400 microns. 6. All three types of correlations were observed mostly in cell pairs with preferred orientations that differed < 45 degrees at all ages studied. In the fourth to sixth week, however, the similarity of orientation preference was not strict, and correlated firings were observed even in a pair with orthogonal orientation preferences; whereas in the seventh to ninth week the tuning became sharper. 7. These results suggest that functional interactions between cortical neurons exist but are much less specific with respect to horizontal separation and orientation preference before the sixth week of age, and these interactions become more specific so as to operate between neurons with similar orientation preferences in more restricted region after the seventh to ninth week of age and thus in adulthood.

Aging↗
PubMed1993

Application of limulus test (G pathway) for the detection of different conformers of (1-->3)-beta-D-glucans.

The reactivity of factor G mediated coagulation pathway in limulus amebocyte lysate which is triggered by (1-->3)-beta-D-glucans is thought to depend on the structure of the glucans, especially on the ultrastructure: triple helix, single helix and random coil. We used Sonifilan (SPG) and grifolan (GRN) as parent compounds to compare the reactivities of these three conformers. Under a neutral condition, alkaline treated SPG (SPG-OH, single helix) and polycarboxylated SPG (PC-SPG, random coil) showed significantly stronger reactivity than untreated SPG (triple helix). After the alkaline treatment, all three conformers showed comparable reactivities. It is suggested that the pretreatment of the glucan preparations by sodium hydroxide is quite important to compare quantitatively the reactivity of the glucans by limulus test, and comparing the data of untreated and alkaline treated glucans would provide information about their conformations. Using this approach, it was found that after heat treatment at around 150 degrees C, the conformation of GRN was changed to rich in the triple helix, and that following sodium hydroxide treatment and dialysis of GRN, the conformation of GRN was changed to single helix rich conformer. About half of the single helix conformer was gradually changed to triple helix conformer over one week at 4 degrees C.

Carbohydrate Conformation↗
PubMed1993

Cardiopulmonary effects of a combination of medetomidine and butorphanol in atropinized pigs.

Cardiopulmonary effects of a combination of medetomidine and butorphanol were evaluated in atropinized pigs. This combination unchanged the cardiac output and significantly lowered the oxygen consumption compared with base-line values. Although some statistically significant changes were recorded, both medetomidine and butorphanol did not have a marked effect on the cardiopulmonary parameters in atropinized pigs. It was indicated that the administration of the combination of medetomidine and butorphanol is relatively safe in atropinized pigs.

Adrenergic alpha-Agonists↗
PubMed1993

Comparison of sedative and analgesic/anesthetic effects induced by medetomidine, acepromazine, azaperone, droperidol and midazolam in laboratory pigs.

The sedative and analgesic/anesthetic effects of medetomidine, acepromazine, azaperone, droperidol and midazolam were compared in laboratory pigs. In these sedatives, medetomidine produced the most profound degree of sedation with greater drowsiness than was achieved by other sedatives tested. Medetomidine induced sedation accompanied with weak analgesia and muscle relaxation smoothly and quickly and depressed arousal reaction deeply as compared with other sedatives. Pigs given medetomidine were not aroused easily even by moderately rough stimulation for approximately 60 min after injection.

Acepromazine↗
PubMed1993

Sedative effect induced by a combination of medetomidine and midazolam in pigs.

Sedative and analgesic/anesthetic effects induced by a combination of medetomidine and midazolam were evaluated in pigs. This combination exerted a much more potent sedative effect than that induced by a medetomidine alone, even if the dose of medetomidine was reduced to one half, and even if the pigs were stimulated continuously during the induction phase. Pigs given this combination were induced to sedation smoothly and very quickly. During being sedated the arousal reaction induced by sensory stimuli were depressed profoundly and pigs could be placed in dorsal recumbency without any resistance. In addition, this combination produced moderate analgesic effect and apparent muscle relaxation. This potent effect induced by this combination seemed to be induced by a synergistic interaction between medetomidine and midazolam because the sedative effect achieved with this combination was much greater than that which could be expected from a simple additive response of both sedatives. This sedative combination may be a widely available and valuable for chemical restraint in pigs.

Analgesia↗
PubMed1993

Antagonistic effects of atipamezole and flumazenil on medetomidine-midazolam induced sedation in laboratory pigs.

Antagonistic effects of atipamezole (80, 160 and 240 micrograms/kg, im), and flumazenil (100 micrograms/kg, iv) or atipamezole (80 micrograms/kg) and flumazenil (100 micrograms/kg) on medetomidine-midazolam induced sedation were evaluated in laboratory pigs. Atipamezole at each dose effectively reversed sedation, and the arousal time, standing time and total recovery time were significantly shortened. The optimal action of atipamezole was seen at a dose of 160 micrograms/kg. At this dose recovery from the sedation was quick and smooth, and adverse effects such as hyperactivity or tachycardia were minimal. Flumazenil reversed sedation temporary, but the pigs went back to moderate sedation soon after arousal. The combination of atipamezole and flumazenil most effectively reversed the sedation, however atipamezole (160 micrograms/kg) alone was thought to be practically potent enough to antagonize sedation induced by medetomidine-midazolam in laboratory pigs.

Adrenergic alpha-Antagonists↗
PubMed1993

[Postoperative pain relief by continuous epidural infusion: a comparison of three solutions].

The effect of three solutions on postoperative pain relief by continuous epidural infusion was studied. Seventy-five patients after upper or lower abdominal surgeries were assigned to one of three groups and the postoperative pain relief was evaluated for 48 hours. Group I: bolus injection of buprenorphine (Bn) 0.1 mg + saline (S) 8 ml and continuous infusion (2 ml.h-1) of Bn 0.8 mg + S 92 ml; Group II: bolus injection of Bn 0.1 mg + 0.5% bupivacaine (Bc) 4 ml + S 4 ml and continuous infusion of Bn 0.8 mg + S 92 ml; Group III: bolus injection of Bn 0.1 mg + 0.5% Bc 4 ml + S 4 ml and continuous infusion of Bn 0.8 mg + 0.5% Bc 40 ml + S 60 ml. The combination of buprenorphine with low-dose bupivacaine (Group III) offered the most effective postoperative analgesia in three groups without increasing the frequency of adverse effects induced by epidural administration of local anesthetics. However, even in Group III, the percentage of patients complaining of pain at bed rest was still high during early postoperative period (56% at 6 hours postoperatively). The results suggest that further consideration is necessary on agents selection and dosage adjustment for the postoperative epidural analgesia.

Aged↗
PubMed1993

[Comparison of buprenorphine and fentanyl for postoperative pain relief by continuous epidural infusion].

This study examined analgesic efficacy and adverse effects of buprenorphine and fentanyl for the postoperative pain relief by continuous epidural infusion. Fifty patients after upper or lower abdominal surgeries were assigned to two groups and buprenorphine and fentanyl were epidurally administered postoperatively. Buprenorphine (B) group received bolus injection of B 0.1mg + saline 8 ml and continuous infusion of B 0.8 mg+saline 92 ml (2 ml.h-1). Fentanyl group received bolus injection of F 0.1 mg+saline 6 ml and continuous infusion of F 0.6 mg+saline 84 ml (2 ml.h-1). There was no significant difference between the two groups in the analgesic efficacy, which became lower from 2 to 12 hours postoperatively. However, compared with buprenorphine group, the incidence of nausea or vomiting and dizziness was significantly less in the fentanyl group (11 vs. 4 cases and 7 vs. 1 cases). These results imply that the major site of action of epidurally administered fentanyl is the spinal cord. In contrast, analgesic effect of epidural buprenorphine appears to be enhanced by the supraspinal action. We conclude that fentanyl is superior to buprenorphine for postoperative pain relief by continuous epidural infusion.

Abdomen↗
PubMed1993

[The quantitative assay of (1-->3)-beta-D-glucan in culture medium of Candida albicans using G-test].

It has been difficult to diagnose the deep-seated fungal infection. Limulus test which originally has been developed to detect endotoxin in blood is also activated by (1-->3)-beta-D-glucan, the cell wall component of the fungi. Factor G in limulus lysate is activated by (1-->3)-beta-D-glucan and not by endotoxin. The quantitative assay of (1-->3)-beta-D-glucan is possible by the G-test using factor G. (1-->3)-beta-D-glucan in RPMI culture medium of Candida albicans was periodically measured using G-test and the effect of antifungal drug or neutrophil to the changes of (1-->3)-beta-D-glucan in the culture medium was studied. Increase in the level of (1-->3)-beta-D-glucan was in parallel with the growth of Candida albicans. G-test may be applied to the clinical diagnosis of fungal infection.

Candida albicans↗