Biomedical subjects

H Kodama

Publications and source records attributed to H Kodama.

At least 181 records · Page 10Linked to original sources

PubMed1998

Interaction and orientation of an alpha-aminoisobutyric acid- and tryptophan-containing short helical peptide pore-former in phospholipid vesicles, as revealed by fluorescence spectroscopy.

The interaction and orientation of a membrane protein ion channel model, an alpha-aminoisobutyric acid analogue of gramicidin B (GBA), in egg yolk phosphatidylcholine vesicles was studied by means of fluorescence spectroscopic techniques. GBA helices form stable ion-conducting pores in membranes [Jelokhani-Niaraki et al. (1995) J. Chem. Soc. Perkin Trans. 2, 801-808]. In an alpha-helical model for the peptide, all Trp residues (intrinsic fluorophores) are distributed near the C-terminus. Fluorescence quenching experiments revealed the exposure of the helical peptides' C-termini to aqueous environments. Dansyl-labeled vesicles were used to investigate the GBA dynamism of the interaction with membranes. It was shown that considerable amounts of peptide reside on and in the vicinity of the outer surface of lipid bilayers. The transmembrane transfer to the inner layer is slow due to the high affinity of Trp residues for bilayer interfaces which anchor the peptide to the outer surface. A structural-functional interpretation of the GBA interaction with membranes is presented.

Gramicidin↗

PubMed1998

Effect of tylosin tartrate (Tylan Soluble) on cellular immune responses in chickens.

Although many antimicrobial agents have been reported to cause immunosuppression in animals, macrolide antibiotics enhance immune function. Tylosin is a macrolide antibiotic approved for the control of mycoplasmosis in poultry. The purpose of this investigation was to determine the effect of tylosin on cellular immune functions in chickens. There was no significant difference in adherent splenocyte chemotaxis between tylosin-treated and untreated (control) chickens. Tylosin increased splenocyte proliferation and splenocyte conditioned medium (CM) proliferative activity above control levels. Removal of adherent splenocytes before preparation of CM caused a reduction in CM proliferative activity. Tylosin also increased antitumor activity of splenocytes. These data are the first to suggest that the macrolide antibiotic, tylosin tartrate, has a modulatory effect in chickens on the immune parameters studied.

Animals↗

PubMed1998

Characterization of transgenic tobacco with an increased alpha-linolenic acid level

Microsomal omega-3 fatty acid desaturase catalyzes the conversion of 18:2 (linoleic acid) to 18:3 (alpha-linolenic acid) in phospholipids, which are the main constituents of extrachloroplast membranes. Transgenic tobacco (Nicotiana tabacum) plants with increased 18:3 contents (designated SIIn plants) were produced through the introduction of a construct with the tobacco microsomal omega-3 fatty acid desaturase gene under the control of the highly efficient promoter containing the E12Omega sequence. 18:3 contents in the SIIn plants were increased by about 40% in roots and by about 10% in leaves compared with the control plants. With regard to growth at 15 degreesC and 25 degreesC and the ability to tolerate chilling at 1 degreesC and 5 degreesC, there were no discernible differences between the SIIn and the control plants. Freezing tolerance in leaves and roots, which was assessed by electrolyte leakage, was almost the same between the SIIn and the control plants. The fluidity of plasma membrane from the SIIn plants was almost the same as that of the control plants. These results indicate that an increase in the 18:3 level in phospholipids is not directly involved in compensation for the diminishment in growth or membrane properties observed under low temperatures.

Journal Article↗

PubMed1998

A novel cis-acting element in promoters of plant B-type cyclin genes activates M phase-specific transcription.

Plant B-type cyclin genes are expressed late in the G2 and M phases of the cell cycle. Previously, we showed that the promoter of a Catharanthus roseus B-type cyclin, CYM, could direct M phase-specific transcription of a beta-glucuronidase reporter gene in synchronously dividing BY2 tobacco cells. In this study, we determined the regulatory elements contained within the CYM promoter by using a luciferase reporter gene. Mutational analysis showed that a 9-bp element is essential for M phase-specific promoter activity in synchronized BY2 cells. The CYM promoter contains three other sequences similar to this element. A gain-of-function assay demonstrated that when fused to a heterologous promoter, these elements are sufficient for M phase-specific expression; therefore, we named these elements M-specific activators (MSAs). We found MSA-like sequences in B-type cyclin promoters from tobacco, soybean, and Arabidopsis as well as in the promoters of two M phase-specific genes, NACK1 and NACK2, which encode tobacco kinesin-like proteins. Thus, MSA may be a common cis-acting promoter element that controls M phase-specific expression of cell cycle-related genes in plants.

Base Sequence↗

PubMed1998

Antitumor effect of diphtheria toxin A-chain gene-containing cationic liposomes conjugated with monoclonal antibody directed to tumor-associated antigen of bovine leukemia cells.

Monoclonal antibody c143 against tumor-associated antigen (TAA) expressed on bovine leukemia cells was conjugated to cationic liposomes carrying a plasmid pLTR-DT which contained a gene for diphtheria toxin A-chain (DT-A) under the control of the long terminal repeat (LTR) of bovine leukemia virus (BLV) in the multicloning site of pUC-18. The specificity and antitumor effects of the conjugates were examined in vitro and in vivo using TAA-positive bovine B-cell lymphoma line as the target tumor. In vitro studies with the TAA-positive cell line indicated that luciferase gene-containing cationic liposomes associated with the c143 anti-TAA monoclonal antibody caused about 2-fold increase in luciferase activity compared with cationic liposomes having no antibody, and also that the c143-conjugated cationic liposomes containing pLTR-DT exerted selective growth-inhibitory effects on the TAA-positive B-cell line. Three injections of pLTR-DT-containing cationic liposomes coupled with c143 into tumor-bearing nude mice resulted in significant inhibition of the tumor growth. The antitumor potency of the c143-conjugated cationic liposomes containing pLTR-DT was far greater than that of normal mouse IgG-coupled cationic liposomes containing pLTR-DT as assessed in terms of tumor size. These results suggest that cationic liposomes bearing c143 are an efficient transfection reagent for BLV-infected B-cells lymphoma cells, and that the delivery of the pLTR-DT gene into BLV-infected B-cells by the use of such liposomes may become a useful technique for gene therapy of bovine leukosis.

Animals↗

PubMed1998

Effect of tylosin tartrate on humoral immune responses in chickens.

While many antimicrobial agents have been reported to cause immunosuppression in animals, macrolide antibiotics enhance the immune function. Tylosin tartrate is a macrolide antibiotic approved for the control of mycoplasmosis in poultry. The purpose of this investigation was to determine the effect of tylosin on the humoral immune functions in chickens. Three days after oral tylosin tartrate administration, 4- or 8-week-old chickens were immunized intravenously with carbolic acid-killed Brucella abortus bacterin or sheep red blood cells. Seven days (plasma antibodies titre) or 4 days (antibody forming cells) post-immunization, there was a significant increase in antibody production as well as in the numbers of antibody-producing cells in tylosin tartrate-administered chickens compared with the untreated controls. However, 3 days after tylosin tartrate administration, there was no difference in the distribution of T-lymphocyte subpopulations (CD4 or CD8 positive cells) or B lymphocytes (surface immunoglobulin positive cells) in either the peripheral blood or spleens or untreated control chickens.

Animals↗

PubMed1998

In vitro and in vivo antidermatophyte activities of NND-502, a novel optically active imidazole antimycotic agent.

In vitro and in vivo antidermatophyte activities of NND-502, a new imidazole antimycotic agent, were compared with those of two existing antifungal agents, lanoconazole and terbinafine. NND-502 exhibited strong in vitro antifungal activity against Trichophyton spp.; its MIC was 1 to 4 times lower than that of lanoconazole or terbinafine. In an in vivo study with a guinea pig model of tinea pedis, 7-day topical treatment with a 0.5% solution of NND-502 (dissolved in polyethylene glycol 400) was more effective than that with a 0.5% solution of either lanoconazole or terbinafine for eradicating fungi from the infected feet. When the duration of treatment was shortened to 3 days, a topical 1% solution of NND-502 achieved a complete mycological cure, while topical 1% solutions of lanoconazole and terbinafine did not.

Animals↗

PubMed1998

Progressive lineage analysis by cell sorting and culture identifies FLK1+VE-cadherin+ cells at a diverging point of endothelial and hemopoietic lineages.

Totipotent murine ES cells have an enormous potential for the study of cell specification. Here we demonstrate that ES cells can differentiate to hemopoietic cells through the proximal lateral mesoderm, merely upon culturing in type IV collagen-coated dishes. Separation of the Flk1+ mesoderm from other cell lineages was critical for hemopoietic cell differentiation, whereas formation of the embryoid body was not. Since the two-dimensionally spreading cells can be monitored easily in real time, this culture system will greatly facilitate the study of the mechanisms involved in the cell specification to mesoderm, endothelial, and hemopoietic cells. In the culture of ES cells, however, lineages and stages of differentiating cells can only be defined by their own characteristics. We showed that a combination of monoclonal antibodies against E-cadherin, Flk1/KDR, PDGF receptor(alpha), VE-cadherin, CD45 and Ter119 was sufficient to define most intermediate stages during differentiation of ES cells to blood cells. Using this culture system and surface markers, we determined the following order for blood cell differentiation: ES cell (E-cadherin+Flk1-PDGFRalpha-), proximal lateral mesoderm (E-cadherin-Flk1+VE-cadherin-), progenitor with hemoangiogenic potential (Flk1+VE-cadherin+CD45-), hemopoietic progenitor (CD45+c-Kit+) and mature blood cells (c-Kit-CD45+ or Ter119+), though direct differentiation of blood cells from the Flk1+VE-cadherin- stage cannot be ruled out. Not only the VE-cadherin+CD45- population generated from ES cells but also those directly sorted from the yolk sac of 9.5 dpc embryos have a potential to give rise to hemopoietic cells. Progenitors with hemoangiogenic potential were identified in both the Flk1+VE-cadherin- and Flk1+VE-cadherin+ populations by the single cell deposition experiment. This line of evidence implicates Flk1+VE-cadherin+ cells as a diverging point of hemopoietic and endothelial cell lineages.

Animals↗

PubMed1998

Correlation between the drinkability of beer and gastric emptying.

A subjective evaluation of beer drinkability and the degree of stomach fullness were found to correlate with the relaxed cross-sectional area of the pylorus antrum measured by real-time ultrasonography. Five kinds of beer with a different malt/adjuncts ratio and degree of attenuation were used. Each beer was given to 9 healthy volunteers at the rate of 3 ml/kg/15 min, and they each recorded the degree of stomach fullness, desire to drink and tastiness every 30 min. With increasing volume drunk, the degree of tastiness and desire to drink were lowered, and the degree of stomach fullness raised. The relaxed cross-sectional area of the pylorus antrum measured by an ultrasonic image analyzer every 30 min was highly correlated with the degree of stomach fullness, tastiness of the beer, and desire to drink (p = 0.0021, < 0.0001, 0.001). The beer giving the lowest degree of stomach fullness was appraised to be tasty and highly drinkable. These findings suggest that the rate of gastric emptying is one of the factors determining the drinkability of beer, and that measurement of the relaxed cross-sectional area of the pylorus antrum is useful to evaluate stomach fullness during beer drinking.

Adult↗

PubMed1998

Antibody response in the intestinal tract of mice orally immunized with antigen associated with liposomes.

In order to evaluate the usefulness of liposomes, which are stable in acidic solution, bile and pancreatin solution (stable liposomes), as vehicle for oral vaccines, the intestinal IgA antibody responses of mice to liposome-associated antigen after oral administration were examined. The intestinal IgA antibody responses against ganglioside GM1 were detected after the oral immunization of ganglioside GM1-containing stable liposomes. When monophosphoryl lipid A was incorporated into stable liposomes containing ganglioside GM1, further augmentation of IgA responses to ganglioside GM1 was observed. On the other hand, the oral administration with ganglioside GM1 alone was unable to induce any detectable intestinal anti-ganglioside GM1 IgA antibody response. These results suggest that liposomes which are stable in acidic solution, bile, and pancreatin solution would serve effectively as an oral delivery vehicle for inducing mucosal immune responses.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed1998

Cytotoxicity induced by recombinant human tumor necrosis factor-alpha dependent on the types of its receptors on canine cells.

Based on the recent findings that show how recombinant human tumor necrosis factor (rh-TNF)-alpha has potent antitumor activity on human cancer patients when it locally administrated, we have tested the cytotoxicity of rh-TNF-alpha on 3 canine cultured cells: (1) canine kidney carcinoma (CKCa-1), (2) mastocytoma and (3) Mardin Darby canine kidney cells (MDCK). The cell surface expression of TNF-alpha receptors on these canine cells was also determined with anti-human TNF RI and RII polyclonal antibodies. Our data shows that on CKCa-1 which has TNF RI receptors rh-TNF-alpha induced cytotoxicity. By contrast, it exhibited no toxicity on canine mastocytoma which has mainly RII receptors. The data also suggest actinomycin D (ACT-D), an anticancer antibiotic, enhanced the cytotoxicity of rh-TNF-alpha. Combined with ACT-D, rh-TNF-alpha showed the cytotoxicity on MDCK which possessed both TNF RI and RII receptors. The results indicate that the cytotoxicity of rh-TNF-alpha depends on the presence of TNF RI receptors on canine tumor cells.

Animals↗

PubMed1998

GH and zinc treatments for short stature caused by steroid treatments in a young patient with autoimmune hepatitis (type 1).

An 8-yr-old boy with autoimmune chronic active hepatitis (AiCAH) was treated with steroid hormones. Liver function improved with this treatment, but the patient's growth was severely disturbed. At the age of 10 y, GH treatment was added to the steroid therapy because of his short stature (height: -2.5 SD), but in the following 12 months, he only grew 2 cm. Oral administration of zinc (5 mg/kg/day) was also added to the patient's therapy, but his height has not improved in the 12 months of this combined therapy.

Body Height↗

PubMed1998

Characterization of stress-induced sudden death in cardiomyopathic hamsters.

Stress is known clinically and experimentally to contribute to the development or exacerbation of cardiovascular dysfunction. In an attempt to construct an animal model of stress-induced cardiovascular dysfunction and to understand its mechanisms, the effects of cold-immobilization stress and its cardiovascular consequences were investigated in cardiomyopathic Syrian hamsters (BIO 14.6) and age-matched healthy control hamsters. Repeated exposure (5 days) to cold-immobilization in the supine position induced no detectable ill effects in the healthy control hamsters but had a lethal effect in the cardiomyopathic hamsters: more than half of the animals died suddenly during or after the stress sessions. Autopsy study of these animals showed significant increases in the weights of the heart, adrenal, liver and kidney and in the serum levels of alkaline phosphatase, urea nitrogen, creatinine and glucose in the cardiomyopathic hamsters subjected to the stress. Propranolol (0.1-10 mg/kg i.p.) administered just before each cold-immobilization for 5 consecutive days dose-dependently and significantly prevented the lethal effects of the stress. Furthermore, it was demonstrated that the drug significantly reduced the increase in the weights of the heart, adrenal, liver and kidney observed in the stressed cardiomyopathic hamsters, whereas phentolamine (0.1-10 mg/kg) and atropine (0.1-10 mg/kg) did not prevent the stress-induced sudden death. The series of acute experiments using single exposure of this stress revealed that the stress evoked severe arrhythmia in some of the cardiomyopathic hamsters and increased the levels of circulating catecholamines in both healthy and cardiomyopathic hamsters. These results taken together suggest that stress accelerates the cardiovascular dysfunction in cardiomyopathic hamsters and provide the first evidence that excitation of the sympathetic nerves, in which beta-adrenoceptors appear to be involved, but not the parasympathetic nerves, has an important role in the etiology of stress-induced cardiac sudden death of cardiomyopathic hamsters.

Animals↗

PubMed1998

[Advantages and disadvantages of SMANCS-Lipiodol intrahepatic arterial infusion chemotherapy for unresectable hepatocellular carcinoma].

Though SMANCS-Lipiodol suspension has advantages over tumor regression, its disadvantages should also be considered: (1) Anaphylactic reaction due to its high molecular weight. (2) Since it readily destroys the tissue, a smaller dose and repeated administration are required. (3) Due to its low viscosity, it easily enters the arterioles and causes damage even to the extrahepatic organs. When this drug is infused into the left hepatic artery in subsegmental fashion, it enters the neighboring gastric tissues through the communication of the left hepatic and left gastric arteries, and this ultimately causes intractable gastric ulcers. Considering the above facts, this drug should be used carefully.

Adult↗

PubMed1998

Flt3/Flk-2 and c-Kit are not essential for the proliferation of B lymphoid progenitor cells in the bone marrow of the adult mouse.

The receptor tyrosine kinase Flk-2/Flt3 was originally cloned from hematopoietic stem cell-enriched fetal liver and placenta and is believed by some investigators to play a role in the regulation of the hematopoietic stem cell. However, targeted disruption of the flt3 gene results in a specific deficiency in early B cell progenitors. Using an antagonistic monoclonal antibody developed against the extracellular domain of Flt3, we investigated the expression and function of the molecule on B lymphoid lineage cells in the bone marrow (BM) of adult mice. Approximately 10% of B220+ cells in the BM expressed Flt3 on the cell surface, and most of the cells belonged to a pro-B cell fraction when judged by an expression pattern of CD43, heat-stable antigen, and BP-1. However, B lymphoid precursor cells that are clonable in vitro could not be enriched in the B220+/Flt3+ cell fraction sorted by flow cytometry. Furthermore, proliferation of B lymphoid precursor cells in the adult BM was not blocked by administration of the antagonistic monoclonal antibodies against Flt3 and c-Kit, suggesting that signalings mediated by Flt3 and c-Kit receptors are not essential for the proliferation of B cell progenitors in adult mouse BM.

Animals↗

PubMed1997

Simultaneous determination of creatinine, creatine, and guanidinoacetic acid in human serum and urine using liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.

A rapid and direct method for simultaneous determination of creatinine, creatine, and guanidinoacetic acid in biological samples has been developed by using column liquid chromatography-mass spectrometry (LC/APCI-MS). The determinations of creatinine, creatine, and guanidinoacetic acid in the samples of human urine and serum were carried out by scanning the [M + H]+ ions of each compound. The recoveries of authentic compounds were 93.87 +/- 6.00% (n = 5) for creatinine, 94.80 +/- 8.93% (n = 5) for creatine, and 90. 92 +/- 7.96% (n = 5) for guanidinoacetic acid after ion-exchange resin treatment. The content of creatinine in human urine and serum was also measured by the Jaffé method, a common method of determination of creatinine currently used in hospitals. The contents of creatinine, creatine, and guanidinoacetic acid obtained using LC/APCI-MS coincided well with those reported in previous papers.

Atmospheric Pressure↗

PubMed1997

Priming effect of N-acetyl-S-(3-oxo-3-carboxy-n-propyl)cysteine in human neutrophils and tyrosyl phosphorylation of 45 kDa protein.

Human peripheral blood polymorphonuclear leukocytes were preincubated with N-acetylcystathionine and N-acetyl-S-(3-oxo-3-carboxy-n-propyl)cysteine (NAc-OCPC) found in the urine of a patient with cystathioninuria. NAc-OCPC significantly enhanced the N-formyl-methionyl-leucyl-phenylalanine-induced superoxide generation, whereas N-acetylcystathionine did not enhance the superoxide generation. When the cells were incubated with NAc-OCPC, the tyrosyl phosphorylation of 45 kDa protein of the cell was markedly increased with time. The phosphorylation process was dependent on the concentration of NAc-OCPC. Both the superoxide generation and the tyrosyl phosphorylation of 45 kDa protein increased by NAc-OCPC were inhibited by genistein and herbimycin A, the inhibitors of protein tyrosine kinase, but were rather enhanced by staurosporine, an inhibitor of protein kinase C.

Amino Acids↗

PubMed1997

Simultaneous determination of urinary cystathionine, lanthionine, S-(2-aminoethyl)-L-cysteine and their cyclic compounds using liquid chromatography-mass spectrometry with atmospheric pressure chemical ionization.

A measurement system for cystathionine (Cysta) lanthionine (LT), and S-(2-aminoethyl)-L-cysteine (AEC), and reduced products of their ketimines, perhydro-1,4-thiazepine-3,5-dicarboxylic acid (PHTZDC), 1,4-thiomorpholine-3,5-dicarboxylic acid (TMDA) and 1,4-thiomorpholine-3-carboxylic acid (TMA) in the urine samples of a patient with cystathioninuria and normal human subjects has been developed, using column liquid chromatography-mass spectrometry. The recoveries were about 90-105% for Cysta, LT and AEC, and about 77-87% for PHTZDC, TMDA and TMA after ion-exchange treatment. The concentrations of Cysta and PHTZDC in the urine of a patient with cystathioninuria were much higher compared with those in the urine of normal human subjects. The concentrations of AEC and TMDA were almost the same. LT and TMA could not be detected in the urine samples by this method. This method proved useful for the determination of sulfur-containing amino acids and their cyclic compounds in biological samples.

Alanine↗