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Biomedical subjects

K Asano

Publications and source records attributed to K Asano.

At least 307 records · Page 17Linked to original sources
PubMed1992

Chemical modification of recombinant human granulocyte colony-stimulating factor by polyethylene glycol increases its biological activity in vivo.

Recombinant human granulocyte colony-stimulating factor (rHuG-CSF) produced in Escherichia coli was chemically modified by polyethylene glycol (PEG) of molecular weights 4,500 or 10,000. The neutrophils observed at 32 hours after intravenous injection of the rHuG-CSF modified with PEG (4,500) or PEG (10,000) to mice were, respectively, 2.5 times and 5 times more than that observed after the injection of the unmodified rHuG-CSF. These results show that the covalent attachment of PEG to rHuG-CSF enhanced its pharmacological activity in vivo and that the modification with the larger PEG molecule is more effective to enhance the in vivo activity of rHuG-CSF.

Animals↗
PubMed1992

The effects of phentolamine and nitroglycerin on right-sided hemodynamics in cardiac patients can be explained by a shift of the systemic venous return curve and right-ventricular output curve.

The present study investigated the effects of phentolamine (PH) and nitroglycerin (NG) on the hemodynamics of the right heart in patients with cardiac disease. The patients were divided into a well-functioning left heart group (W group, n = 15) and a poorly-functioning left heart group (P group, n = 15). Right cardiac hemodynamic parameters and plasma noradrenaline (NA) and adrenaline (A) concentrations were measured before and after administering PH (0.1 mg/kg, i.v.) or NG (0.6 mg, sublingual). In a parallel animal study we obtained a systemic venous return curve by measuring mean circulatory pressure (MCP), mean right atrial pressure (RAP) and cardiac output, before and after administering PH (0.1 mg/kg, i.v.) or NG (12.5 micrograms/kg, i.v.) to anesthetized open-chest dogs (n = 14). We used MCP data (W group: 7.5 mmHg, P group: 10 mmHg) obtained in a separate series of human studies in our laboratory. We constructed the venous return curve by connecting the MCP point on abscissa with the cardiac index (CI)-RAP plot obtained in the clinical study. We also constructed the right ventricular output curve by connecting the point of -2 mmHg on the abscissa with the CI-RAP plot. We obtained the following results: (1) PH shifted the CI-RAP plot to the left and upwards, while NG shifted the CI-RAP plot to the left almost horizontally on the CI-RAP plane, where CI was plotted on ordinate and RAP on abscissa. The length [formula: see text] C = control point, PH = point after PH) of the shift of CI-RAP plot due to PH was greater in the P group than in W group, while there was no difference in the length [formula: see text] C = control point, NG = point after NG) of the shift of CI-RAP plot due to NG between P and W groups. (2) Both PH and NG significantly elevated plasma NA and A concentrations in both the W and P groups. In the P group, PH increased the plasma NA concentration significantly more than did NG, but both drugs increased plasma A concentration to a similar extent. (3) Both PH and NG significantly decreased the mean pulmonary arterial pressure with NG doing so significantly more than PH.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1992

The role of recombinant human tissue-type plasminogen activator in the treatment of acute pulmonary thromboembolism.

The effect of intravenous recombinant human tissue-type plasminogen activator (tPA) on arterial blood gases was compared with the effect of heparin treatment in acute pulmonary thromboembolism. Fifteen patients received heparin alone (group A), 5 cases were treated with 7.7 x 10(6) I.U. of tPA (group B) and 10 cases with 15 x 10(6) I.U. of tPA (group C) combined with heparin treatment. Arterial oxygen tension before treatment was not significantly different among the three groups. PaO2 was dramatically improved on the 1st day in group C. By the 7th day, PaO2 of group B had improved to the level of group C. However, the PaO2 of group A on the 7th day was not significantly different compared to the pre-treatment value. In group C, post-treatment perfusion lung scintigrams were improved compared to the pre-treatment images, but this was not the case in group B. Treatment with tPA is more effective for acute pulmonary thromboembolism than heparin alone and a high dose of tPA (15 x 10(6) I.U.) leads to rapid improvement in arterial blood gases and lung perfusion images.

Acute Disease↗
PubMed1992

[Analysis of tumor volume in latent prostatic carcinoma].

An assessment has been made of the histopathological characteristics of latent prostatic carcinoma and the tumor volume in 500 male Japanese patients who underwent dissection at The Jikei University since 1983. A microscopic observation was made of the prostatic glands extirpated totally at the necropsy, fixed with formalin and prepared as a step-section in a thickness of 3 mm. In the cases of latent carcinoma, after photographing the lesion in the same magnification and measuring the area of the carcinoma lesion with a digitizer, the volume was calculated by multiplying the thickness of 3 mm, and carcinoma volume was determined by integrating the value of each slice and adjusted by a conversion formula. The incidence of latent carcinoma was 104 cases out of 500 (22%). The incidence increased as the age layer becomes higher, and latent carcinoma was observed in 44% of the patients aged 80 and above. Complication of latent carcinoma with prostatic hyperplasia was presumed to be an independent phenomenon in so far as it is seen from the statistical aspect. The patients were classified histopathologically into well-differentiated type (64%), mixed type (27%) and poorly-differentiated type (9%), showing high incidence in the low-aged layer of well-differentiated lesions and in the high-aged layer of mixed type lesions and in the high-aged layer of mixed type lesions. The average tumor volume of latent carcinoma was so small as 231 mm3, but many of the lesions in the cases of well-differentiated type were small, being on average 103.9 mm3, but many of the lesions in the cases of poorly-differentiated type were large, being on average 642.2 mm3. Statistically, with a tumor size of 200 mm3 as the boundary, a difference was observed in the distribution of histological constitution between the group with smaller lesions and the group with larger lesions. As an application of this result to the clinical carcinoma of stage A, the value of volume of 200 mm3 was considered to be important as a diagnostic criterion in deciding the necessity of treatment.

Adenocarcinoma↗
PubMed1992

[Alteration of oxygen extraction and blood flow in various organs under acute hypoxia].

To assess the compensatory mechanisms involved in maintaining aerobic metabolism in various organs during exposure to acute hypoxia, five anesthetized and paralyzed dogs were ventilated with either normoxic (FIO2: 0.21) or hypoxic gas mixture (FIO2: 0.13). Under both conditions, we examined systemic and pulmonary hemodynamic parameters, and took samples of arterial and mixed venous blood as well as venous blood from various organs including the heart, brain splanchic organs (hepatic vein) and kidney. Based on PO2, PCO2 and pH values as measured with electrodes, we calculated O2 and CO2 contents in each blood sample. The values thus obtained were then used to estimate the O2 extraction ratio (ER), gas exchange ratio (R) and difference of base excess between arterial and venous blood (avBE) in the whole body as well as in each organ. In addition, both O2 delivery (DO2) and O2 consumption (VO2) in the whole body were calculated. Although the whole body showed a decrease in DO2 and an increase in ER during hypoxic gas breathing, other parameters including R, avBE and VO2 did not change significantly. Higher ER values were found in the heart and brain than those in the splanchic organs and kidney, the qualitative trend being the same irrespective of FIO2. On the other hand, increase in ER during hypoxic gas breathing was considerably larger in the splanchic organs and kidney than that in the heart and brain. There was no significant difference in R and avBE in any of the organs between normoxic and hypoxic conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1992

[Pyelolymphatic backflow complicating acute hemorrhagic cystitis: a case report].

The clinical course of a case of pyelolymphatic backflow complicated with acute hemorrhagic cystitis is reported. The patient was a 19-year-old woman. She had disturbed passage in the intravesical ureter due to acute hemorrhagic cystitis caused by adenovirus. Pyelolymphatic backflow occurred because of increased pelvic pressure.

Adenoviridae Infections↗
PubMed1992

[Inhibitory effect of IPD-1151T (suplatast tosilate) on mast cell induction from normal mouse spleen cells].

The effects of IPD-1151T (suplatast tosilate), a novel anti-allergic drug, on murine mast cell induction were examined by the in vitro cell culture technique. Spleen cells from BALB/c mice suspended in RPMI-1640 medium containing interleukin 3 were cultured in the presence or absence of IPD-1151T. Half the volume of the medium was changed every 4 days. Mast cell numbers increased as the culture time went on and reached a peak on the 16th day, when spleen cells were cultured without IPD-1151T. However, induction of mast cells from spleen cell cultures was inhibited by IPD-1151T in a dose dependent fashion. These results strongly suggest that IPD-1151T is a very useful agent for therapy in allergic diseases.

Animals↗
PubMed1992

[Measurements of plasmin-alpha 2 plasmin inhibitor complex and FDP.D dimer levels in the fibrinolytic therapy of acute pulmonary thromboembolism].

The key enzyme for fibrinolysis is plasmin, which is converted from plasminogen by plasminogen activator. Activated plasmin lyses fibrinogen and fibrin to make fibrin degradation products(FDPs) and plasmin is inactivated immediately by alpha 2 plasmin inhibitor. As FDP.D dimer is derived solely from insoluble fibrin, FDP.D dimer is thought of as an index for clot lysis. We measured plasmin-alpha 2 plasmin inhibitor complex(PIC) and FDP.D dimer plasma levels in 3 patients with acute pulmonary thromboembolism treated with recombinant tissue plasminogen activator(tPA). Fifteen million units of tPA(TD-2061) were infused in one hour on the first, second and third hospital days. PIC and FDP.D dimer before tPA infusion showed slightly elevated values as compared to normal ranges. They increased markedly after tPA infusion. These findings suggest that the fibrinolytic system is slightly activated in the acute phase of pulmonary thromboembolism and also strongly activated by tPA infusion. Increased FDP D dimer suggests that fibrin clots are dissolved by activated plasmin. Improvement of arterial oxygen tension was observed after tPA infusion. As sustained higher FDP.D dimer means the existence of fibrin clots, heparin treatment should be continued for prevention of clot formation as long as FDP.D dimer shows higher value. In conclusion, PIC and FDP.D dimer are useful indices not only to detect the activated state of the fibrinolytic system but also to know clot lysis in tPA treatment.

Acute Disease↗
PubMed1992

Automated microanalysis of creatinine by coupled enzyme reactions.

Hydrogen peroxide was generated from creatinine by the sequential enzyme reactions of creatinine amidohydrolase, creatine amidinohydrolase and sarcosine oxidase. Hydrogen peroxide was, in turn, used stoichiometrically for the condensation of 4-aminoantipyrine and N-ethyl-N-(2-hydroxy-3-sulfopropyl)-m-toluidine catalyzed by horse-radish peroxidase, resulting in the formation of quinone dye with maximum absorbance at 546 nm. The optimized assay conditions for the enzymatic determination of creatinine in a HITACHI 7250 autoanalyzer was established. This system, which requires less than 5 microliters of sample, was found to be the most economical for laboratories equipped with autoanalyzers.

Autoanalysis↗
PubMed1991

An induced mRNA secondary structure enhances repZ translation in plasmid ColIb-P9.

Translation of the repZ gene encoding a DNA replication initiation protein of plasmid ColIb-P9 depends on not only the translation of a transcribed leader sequence (repY) but also the specific intergenic base pairing within RepZ mRNA between two short complementary sequences located in the repY and inc gene regions. In addition, repZ translation can be negatively regulated by Inc RNA, the product of the inc gene and a countertranscript to RepZ mRNA. Here we present evidence indicating that a stable secondary structure of RepZ mRNA, designated as structure III, sequesters one of the complementary sequences and the ribosome-binding site, thereby preventing repZ translation. When site-directed mutagenesis was used to destabilize structure III without changing the ribosome-binding site, a significant level of repZ expression was observed even in the absence of repY translation. Under these conditions, however, repZ expression could be substantially reduced by additional mutations that directly diminished the intergenic base pairing at the mRNA level between the two complementary sequences. These results indicate that repY translation is essential for the disruption of structure III by inducing the formation of a new secondary structure through the intergenic base pairing, and more importantly, that this new structure enhances repZ translation. We also found that the site of repY translation termination played a critical role in the intramolecular conformational alteration of structure III.

Bacteriocin Plasmids↗
PubMed1991

Changes in the rat liver mitochondrial DNA upon aging.

During experiments on the molecular basis of morphological and functional changes observed in rat liver mitochondria upon aging, we found that the buoyant density profile of mitochondrial DNA (mtDNA) shows a wide distribution pattern especially in the lighter region than that of young rat liver mtDNA. The heterogeneous pattern may be partly recovered to become similar to that of young rat liver mtDNA by treatment with proteinase K. Therefore, it is quite likely that mtDNA of old rat liver contains firmly bound protein(s) or peptides. During the morphological observation of mtDNA by electron microscopy, we found that mtDNA of old rat had a novel property, that is, the ability to attach to negatively charged mica in the absence of magnesium ions, although their morphological features showing circular 5 microns contour length form did not change. Further, mtDNA gained resistance against EcoRI digestion during aging. This property was not shared by the DNA from young animal, and might be due to the binding protein(s).

Adsorption↗
PubMed1991

Pharmacokinetics of recombinant human granulocyte colony-stimulating factor conjugated to polyethylene glycol in rats.

The pharmacokinetics of recombinant human granulocyte colony-stimulating factor conjugated to polyethylene glycol (PEG-rhG-CSF) and rhG-CSF were studied in male Sprague-Dawley rats. The serum concentration after i.v. administration at a dose of 100 micrograms protein/kg was investigated by a bioassay. The serum rhG-CSF concentration decreased steadily after injection with a terminal half-life of 1.79 h. The PEG-rhG-CSF concentration after injection decreased much more slowly with a half-life of 7.05 h. The slower disappearance of PEG-rhG-CSF resulted in a greater area under the concentration-time curve. The neutrophil count after 100 micrograms of protein/kg of rhG-CSF administration reached a peak 12 h after injection and returned to the control level 48 h after injection. The neutrophil count after 100 micrograms of protein/kg of PEG-rhG-CSF administration was identical to that of rhG-CSF after 12 h but the highest level was maintained for 24 to 72 h after injection and returned to the control level after 168 h. These data indicated that PEG-rhG-CSF administration exerted a sustained biological effect on peripheral blood neutrophils. It is expected that PEG-rhG-CSF may contribute greatly to human G-CSF treatment because it has a prolonged neutrophil-proliferating activity enabling fewer administrations.

Animals↗
PubMed1991

Desensitization of the epidermal adenylate cyclase system: agonists and phorbol esters desensitize by independent mechanisms.

Exposure of pig epidermis to adenylate cyclase stimulators results in receptor-specific desensitization. We investigated the nature of the agonist-induced desensitization, which was compared with the phorbol ester-induced, receptor-nonspecific desensitization. Both phorbol ester-induced desensitization and the agonist-induced desensitization were accompanied by an increase in forskolin- and cholera toxin-induced cyclic AMP accumulations. The magnitude of the increase in the agonist-induced desensitization was parallel to the degree of the initial cyclic AMP accumulation; histamine and adenosine, which increase more cyclic AMP than epinephrine, resulted in a more marked increase in forskolin- and cholera toxin-induced cyclic AMP accumulations. Similarly, epidermis desensitized to multiple receptors revealed more marked forskolin- and cholera toxin-induced cyclic AMP accumulations than epidermis desensitized to a single receptor. In contrast to the phorbol ester-induced desensitization, agonist-induced desensitization was not affected by the protein kinase C inhibitors H-7 and staurosporin. Further, agonist-induced desensitization was still inducible in phorbol ester-desensitized epidermis and vice versa. In contrast to the agonist-induced desensitization, which is accompanied by the preceding adenylate cyclase stimulation, no evidence for the stimulation of the adenylate cyclase during phorbol ester treatment was obtained. Neither agonist-induced desensitization nor phorbol ester-induced desensitization affected the content of inhibitory guanine nucleotide binding protein of the epidermis, which was monitored by the pertussis toxin (IAP)-catalyzed ADP ribosylation reaction. Our results indicate that agonist-induced desensitization and the phorbol ester-induced desensitization are independent of each other. Although both processes are characterized by increased forskolin- and toxin-induced cyclic AMP accumulations, the former is accompanied by initial cyclic AMP accumulation; the latter is not.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1991

Positive and negative regulations of plasmid CoLIb-P9 repZ gene expression at the translational level.

Expression of the repZ gene involved in DNA replication of the ColIb-P9 plasmid depends on translation of a transcribed repZ leader sequence (repY) and is negatively regulated by Inc RNA, the product of the inc gene and a countertranscript to RepZ mRNA. To further understand the regulatory loop of repZ expression, we isolated and characterized replication-defective ColIb-P9 mutants that affected the level of repZ expression. Here we report that mutations occurring in two complementary sequences, one (5'GGCG3') in the inc region and one in the repY region, reduce the level of repZ expression without affecting transcription. The mutations in one complementary sequence were suppressed by compensatory base changes in the other sequence, restoring the ability of repZ expression. These results indicated that interaction by base pairing between the two complementary sequences of RepZ mRNA was essential for repZ translation. The two sequences, separated by 107 bases from each other, have a potential to form a novel pseudoknot in the RepZ mRNA leader. We also found that some mutations in the 5'GGCG3' sequence altered the specificity of Inc RNA, thereby reducing significantly its regulatory activity. Thus, this single specific sequence is involved in both positive and negative regulations for repZ expression. Possible regulatory mechanisms of repZ expression are discussed.

Amino Acid Sequence↗
PubMed1991

Isolation and genetic study of p-fluoro-DL-phenylalanine-resistant mutants overproducing beta-phenethyl-alcohol in Saccharomyces cerevisiae.

p-Fluoro-DL-phenylalanine (PFP)-resistant mutants which produce a large amount of beta-phenethyl-alcohol, a rose-like flavor component, were isolated from the isogenic strains X2180-1A and X2180-1B of Saccharomyces cerevisiae. Cells of these mutants accumulated phenylalanine and tryptophan more than 3-fold times that of wild-type cells, while they accumulated less than half the tyrosine. The activity of prephenate dehydrogenase (PDG) (EC 1.3.1.12) was markedly decreased while that of 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase (EC 4.1.2.15) was increased. Genetic analysis revealed that the mutation occurred at the TYR1 locus, encoding PDG, and that the mutated TYR1 gene, try1-pfp, caused both PFP resistance and beta-phenethyl-alcohol overproduction. This was supported by molecular genetic studies with cloned tyr1-pfp DNA.

Alleles↗
PubMed1991

A mutated ARO4 gene for feedback-resistant DAHP synthase which causes both o-fluoro-DL-phenylalanine resistance and beta-phenethyl-alcohol overproduction in Saccharomyces cerevisiae.

o-Fluoro-DL-phenylalanine (OFP)-resistant mutants which overproduce beta-phenethyl-alcohol were isolated from a laboratory strain of Saccharomyces cerevisiae. Cells of one of the mutants accumulated tyrosine and phenylalanine 1.5-3 fold more than did wild-type cells. Its 3-deoxy-D-arabino-hepturosonate-7-phosphate (DAHP) synthase (EC 4.1.2.15), encoded by ARO4, was free from feedback inhibition by tyrosine. Genetic analysis revealed that the mutation was controlled by a single dominant gene, ARO4-OFP, encoding feedback-resistant DAHP synthase by tyrosine, and that this gene caused both the OFP resistance and beta-phenethyl-alcohol overproduction. This was supported by molecular genetic studies using cloned ARO4 both from the wild-type and its mutant strain.

3-Deoxy-7-Phosphoheptulonate Synthase↗
PubMed1991

Immunological and virological characterization of improved construction of recombinant vaccinia virus expressing rinderpest virus hemagglutinin.

We constructed a recombinant vaccinia virus (RVV) expressing rinderpest virus (RPV) hemagglutinin (H) by modifying the promoter region of the original RVV. The promotor region was modified at three points, i.e., an outframe ATG was eliminated, the sequence between the promoter and initiation codon was shortened and the base sequence just upstream of the initiation codon was changed. As compared with the original RVV, the modified RVV was found to produce a remarkably large amount of H protein in infected rabbit kidney cells cultured in vitro and to induce high titers of anti-RPV-H antibodies in rabbits. The median protective doses in rabbits of the modified and of the original RVVs were 10(2) pfu and 10(3.5) pfu, respectively, indicating that the modified RVV was at least 10-times more effective in protection than the original. The neurovirulence of the modified RVV and the parental LC16mO strain was roughly at the same level, and was much lower than that of WR strain. The modified RVV was as heat-stable as the original one. These results indicate that the modified RVV could be a candidate rinderpest vaccine for further examinations including cattle.

Animals↗