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Biomedical subjects

T Itoh

Publications and source records attributed to T Itoh.

At least 433 records · Page 24Linked to original sources
PubMed1998

Physiological features of visceral smooth muscle cells, with special reference to receptors and ion channels.

Visceral smooth muscle cells (VSMC) play an essential role, through changes in their contraction-relaxation cycle, in the maintenance of homeostasis in biological systems. The features of these cells differ markedly by tissue and by species; moreover, there are often regional differences within a given tissue. The biophysical features used to investigate ion channels in VSMC have progressed from the original extracellular recording methods (large electrode, single or double sucrose gap methods), to the intracellular (microelectrode) recording method, and then to methods for recording from membrane fractions (patch-clamp, including cell-attached patch-clamp, methods). Remarkable advances are now being made thanks to the application of these more modern biophysical procedures and to the development of techniques in molecular biology. Even so, we still have much to learn about the physiological features of these channels and about their contribution to the activity of both cell and tissue. In this review, we take a detailed look at ion channels in VSMC and at receptor-operated ion channels in particular; we look at their interaction with the contraction-relaxation cycle in individual VSMC and especially at the way in which their activity is related to Ca2+ movements and Ca2+ homeostasis in the cell. In sections II and III, we discuss research findings mainly derived from the use of the microelectrode, although we also introduce work done using the patch-clamp procedure. These sections cover work on the electrical activity of VSMC membranes (sect. II) and on neuromuscular transmission (sect. III). In sections IV and V, we discuss work done, using the patch-clamp procedure, on individual ion channels (Na+, Ca2+, K+, and Cl-; sect. IV) and on various types of receptor-operated ion channels (with or without coupled GTP-binding proteins and voltage dependent and independent; sect. V). In sect. VI, we look at work done on the role of Ca2+ in VSMC using the patch-clamp procedure, biochemical procedures, measurements of Ca2+ transients, and Ca2+ sensitivity of contractile proteins of VSMC. We discuss the way in which Ca2+ mobilization occurs after membrane activation (Ca2+ influx and efflux through the surface membrane, Ca2+ release from and uptake into the sarcoplasmic reticulum, and dynamic changes in Ca2+ within the cytosol). In this article, we make only limited reference to vascular smooth muscle research, since we reviewed the features of ion channels in vascular tissues only recently.

Animals↗
PubMed1998

Synthesis of new peptides with prolactin-releasing activity by a combination of recombinant DNA technology and a cysteine-specific cyanylation reaction.

A newly isolated peptide from bovine hypothalamus with prolactin-releasing activity (prolactin-releasing peptide; PrRP) was synthesized by a combination of recombinant DNA technology and a cysteine-specific cyanylation reaction, together with rat and human homologs. The peptides were expressed in the form of fusion proteins with basic fibroblast growth factor mutein, which were purified by heparin-affinity chromatography. The fusion proteins were cleaved at the cysteine residues of the junction site by cyanylation, followed by treatment with ammonia for C-terminal amidation. Purification of the resulting crude peptides was performed using chromatography on a gel-filtration column, a cation-exchange column, and a reversed-phase column. As an example, about 90 mg of bovine PrRP (bPrRP) was obtained from 201 of culture bloth. The purified b PrRP showed full biological activities in binding to its receptor expressed on CHO cells and releasing arachidonic acid metabolite from the same cells, while the C-terminal acid form of bPrRP had little of these activities. These results indicate that the C-terminal amide structure is very important for expressing biological activity. The peptides obtained here might be very useful for studies on their biological significance and roles in vivo.

Amino Acid Sequence↗
PubMed1998

Survival using percutaneous cardiopulmonary support after acute myocardial infarction due to occlusion of the left main coronary artery--a report of two cases.

Two cases of acute myocardial infarction due to an occlusion of the left main coronary artery (LMCA) are presented. Their cardiogenic shock was successfully treated with percutaneous cardiopulmonary support (PCPS), in addition to reperfusion therapy and an intraaortic balloon pump. The 2 patients were able to be weaned from PCPS and discharged from hospital. It is suggested that the early use of PCPS may be life-saving in patients with myocardial infarction due to the occlusion of the LMCA who have progressed to cardiogenic shock.

Acute Disease↗
PubMed1998

Application of two-dimensional mapping for an analysis of galactosyllactoses in yogurt.

A two-dimensional mapping analysis was performed by HPLC for 4 kinds of standard galactosyllactoses (GLs, trisaccharide) which were assumed to be produced from lactose (galactopyranosyl beta 1-->4 glucopyranose) in yogurt during the fermentation of lactic acid bacteria. After the pyridylamination of GLs, they were analyzed by HPLC in the reverse-phase (RP) and anion-exchange (AE) modes. The retention times of each peak obtained were converted to glucose units (GU) in RP mode for the pyridylaminated isomaltooligosaccharides (G1-3) and to relative retention time (RRT) in AE mode against pyridylaminated-isomaltotriose, and then the address data [GU, RRT] were plotted on a graph. This two-dimensional mapping method was found useful for a rapid qualitative evaluation of the chemical structure of trisaccharides formed in yogurt.

Aminopyridines↗
PubMed1998

Molecular cloning and sequencing of two phospho-beta-galactosidase I and II genes of Lactobacillus gasseri JCM1031 isolated from human intestine.

Lactobacillus (Lb.) gasseri JCM1031, which is classified into the B1 subgroup of the Lb. acidophilus group of lactic acid bacteria, characteristically produces two different phospho-beta-galactosidases (P-beta-gal) I and II in the same cytosol as reported in our previous papers [Biosci. Biotech. Biochem., 60, 139-141, 708-710 (1996)]. To clarify the functional and genetic properties of the two enzymes, the structural genes of P-beta-gal I and II were cloned and sequenced. The structural gene of P-beta-gal I had 1,446 bp, encoding a polypeptide of 482 amino acid residues. The structural gene of P-beta-gal II had 1,473 bp, encoding a polypeptide of 491 amino acid residues. The deduced relative molecular masses of 55,188 and 56,243 agreed well with the previous value obtained from the purified P-beta-gal I and II protein, respectively. Multiple alignment of the protein sequence of P-beta-gal I and II with those of P-beta-gals from 5 microorganisms had 30-35% identity on the amino acid level, but those with phospho-beta-glucosidases from 5 microorganisms had the relatively high identity of about 50%. Considering that this strain grows on lactose medium and shows no beta-galactosidase activity, and that purified P-beta-gal I and II can obviously hydrolyze o-nitrophenyl-beta-D-galactopyranoside 6-phosphate (substrate), and also the conservation of a cysteine residue in the molecule, the P-beta-gal I and II were each confirmed as a novel P-beta-gal enzyme.

Amino Acid Sequence↗
PubMed1998

Gassericin A; an uncommon cyclic bacteriocin produced by Lactobacillus gasseri LA39 linked at N- and C-terminal ends.

Gassericin A, a bacteriocin that was produced by Lactobacillus gasseri LA39, was treated with lysylendopeptidase and 3-bromo-3-methyl-2-(2-nitrophenyl-mercapto)-3H-indole. The fragments were recovered by SDS-PAGE and sequenced. All amino acids of gassericin A were distributed by sequence analysis and the bacteriocin did not contain any modified amino acids. The amino acid sequence of gassericin A completely coincided with that found through the cloning of the structural gene. Gassericin A was shown to be a cyclic bacteriocin (class II) which is bound at the N- and C-terminal ends. This is the first example of a cyclic bacteriocin from lactobacilli lactic acid bacteria.

Amino Acid Sequence↗
PubMed1998

Sequence analysis by cloning of the structural gene of gassericin A, a hydrophobic bacteriocin produced by Lactobacillus gasseri LA39.

Gassericin A, a bacteriocin from Lactobacillus gasseri LA39, was purified to homogeneity from the culturesupernatant mainly by reverse-phase chromatography. The molecular weight of gassericin A was found to be 5,652 by mass analysis, unlike the estimated 3,800 found by SDS-PAGE. However, when the purified preparation was treated with lysylendopeptidase, it migrated as a single band to 5,600 with bacteriocin activity on SDS-PAGE. N- and C-terminal amino acids could not be identified. The internal amino acid could be identified after gassericin A was hydrolyzed with lysylendopeptidase. The DNA of the structural gene of gassericin A was sequenced by cloning of the gene from chromosomal DNA with an oligonucleotide probe. The structural gene of gassericin A was found on the chromosomal DNA as an open reading frame encoding a protein composed of 91 amino acids. The amino acid sequence of mature gassericin A was predicted to be 58 residues from the DNA sequence and results of mass analysis. These results suggested that gassericin A has a closed circular structure with N- and C-terminals linked. Gassericin A is a hydrophobic class II bacteriocin; it was 98% identical with acidocin B produced by Lactobacillus acidophilus M46.

Amino Acid Sequence↗
PubMed1998

Repair of ulnar segmental defect by recombinant human bone morphogenetic protein-2 in dogs.

The efficacy of recombinant human bone morphogenetic protein-2 (rhBMP-2) combined with poly D, L lactic-co-glycolic acid (PLGA)/gelatin sponge complex (PGS) as a carrier on the repair of segmental long-bone defects was evaluated using an ulnar model in dogs. The defect was 2 cm in length and was fixed with bone plating. After implantation of PGS with or without rhBMP-2, the repair process of the defect was evaluated by serial radiography until 16 postoperative weeks. All defects treated with 160 micrograms or 640 micrograms of rhBMP-2/PGS revealed bone union radiographically by 12 postoperative weeks, whereas all defects treated with PGS alone revealed no radiographic evidence of healing throughout the experimental period. In defects treated with 40 micrograms of rhBMP-2/PGS, new bone appeared partially at the defects but did not accomplish union. Bone mineral contents at the defect sites after harvest at 16 weeks postoperatively were significantly (p < 0.05) higher in those treated with 160 micrograms or 640 micrograms of rhBMP-2 than in those treated with 40 micrograms of rhBMP-2 or PGS alone. Histologically, defects radiographically diagnosed as having achieved union showed the appearance of cortical bone and bone marrow cells. These findings suggest the use of rhBMP-2/PGS as a potential bone graft substitute in reconstructive surgery in dogs.

Animals↗
PubMed1998

Femoral nonunion fracture treated with recombinant human bone morphogenetic protein-2 in a dog.

This is the first report on successful treatment of spontaneous nonunion fracture of a dog by use of recombinant human bone morphogenetic protein-2 (rhBMP-2). A 4-year-old Pomeranian dog with a 2-year history of femoral nonunion fracture was treated with implantation of rhBMP-2. The dog had received surgical correction twice prior to the admission but radiography of the affected limb revealed a typical figure of nonunion fracture. Glossly, the fractured ends were sclerotic and the area between the ends was filled with fibrous tissue. After debridement the femoral shaft was fixed by an 8-hole plate. rhBMP-2 at a total dose of 256 micrograms was implanted with a synthetic carrier into the 8-mm defect formed by the debridement. Callus formation responding to rhBMP-2 was radiographically observed at 2 weeks after implantation and the defect reached radiographic union by 8 weeks after implantation. The plate was removed at 9 months after implantation. Any complications were not observed for 5 months after removal of the plate.

Animals↗
PubMed1998

Molecular typing of Listeria monocytogenes isolated in Japan by pulsed-field gel electrophoresis.

A total of 40 strains of Listeria monocytogenes which have been demonstrated to be serovar 1/2a, 1/2b, and 4b were genotyped by pulsed-field gel electrophoresis (PFGE) after separate digestion with Apa I, Asc I, Sma I, and Sse 8387 I. Twenty-seven unrelated strains including four representative strains showed distinctly different genotypes according to their PFGE profiles. Then nine strains isolated from shredded cheese of different lots and four strains isolated from the cheese-processing environment were shown to display the same genotype. Therefore, it is suggested that the Listeria was spread in cheese by cross-contamination from the cheese-processing environment. Thus, PFGE analysis has a good typeability and excellent discriminatory power, and has provided a useful tool for investigation of the source of Listeria contamination.

Animals↗
PubMed1998

Veno-right ventricular extracorporeal membrane oxygenation for thoracic surgery: an experimental study in dogs.

BACKGROUND: Although the indications for extracorporeal membrane oxygenation (ECMO) have been extended, ECMO has yet to be used as a respiratory support system during thoracic surgery. The purpose of this experimental study was to investigate whether veno-right ventricular (veno-RV) ECMO can be used for thoracic surgery without mechanical ventilation. METHODS: Acute experimental study: Veno-RV ECMO as total lung support was maintained for 60 min without mechanical ventilation in six dogs. A venous drainage cannula was inserted in the superior cavoatrial junction through the right femoral vein and a venous return cannula was inserted in the right ventricle through the right jugular vein. The veno-RV ECMO system comprised a centrifugal pump and membrane oxygenator. Survival model: After veno-RV ECMO had been established in three dogs, a two-ring thoracic tracheal segment was resected and the tracheal ends were anastomosed by video-assisted thoracic surgery without ventilation. RESULTS: In the acute study, when the veno-RV ECMO flow was maintained at 100 mL/kg/min, all six dogs remained hemodynamically stable and the arterial oxygen saturation was maintained at more than 98%, despite total lung collapse. In the survival study, all three dogs made an uneventful postoperative recovery. CONCLUSION: Video-assisted tracheal surgery can be performed without conventional respiratory support. Veno-RV ECMO as total lung support may become an alternative respiratory management device for thoracic surgery.

Anastomosis, Surgical↗
PubMed1998

Thermoregulation and body fluid osmolality.

Thermoregulatory responses induce dehydration, and dehydration itself raises body temperature, causing an increase in the threshold temperature for cutaneous vasodilatation and sweating, the sensitivity of cutaneous vasodilatation in response to a unit rise in body temperature, and the maximum attainable level of cutaneous circulation, and sweat rate. The reduction of these thermoregulatory responses has been related to hypovolemia and hyperosmolality. Evidence showing the involvement of cardiopulmonary baroreceptors is discussed along with an introduction on the effect of hyperosmolality on skin blood flow and sweating and the involvement of central nervous mechanisms. Heat induced hyperosmolality triggers regulatory responses maintaining blood volume and circulatory function, including a fluid shift between body fluid compartments and the control of fluid intake. Evidence showing the importance of the osmotic regulation of body fluid by drinking is also presented. Finally, the effect of hypovolemia and hyperosmolality under thermal stress due to hot environment or physical activity is discussed from the viewpoint of the interaction between circulation, thermoregulation and body fluid homeostasis.

Animals↗
PubMed1998

Effect of mouse intestinal bacteria on incidence of colorectal tumors induced by 1,2-dimethylhydrazine injection in gnotobiotic transgenic mice harboring human prototype c-Ha-ras genes.

We produced transgenic (Tg) gnotobiotic (GB) mice carrying human prototype c-Ha-ras genes and compared the incidence of colorectal tumors induced by 1,2-dimethylhydrazine (DMH) injection. At 7 to 11 weeks of age, germfree (GF) CB6F1-Tg Hras2 mice were inoculated with various mouse fecal suspensions or mixtures of bacteria isolated from mouse feces. Three weeks after bacterial inoculation, DMH was administered by subcutaneous injection at 20 mg per kg body weight for 20 weeks. Mice were euthanized 5 weeks after the last injection to investigate the number of colorectal tumors. The incidence of colorectal tumors was high in both Tg- and non-Tg-GF mice (100%). In Tg-specific pathogen-free (SPF) mice and Tg-GB-4 mice associated with basic mouse flora consisting of Escherichia coli, lactobacilli, Bacteroides and clostridia, the incidence of colorectal tumors was as high as that in GF mice. In Tg-SPF mice, the tumor score was higher than in Tg-GF mice (p < 0.01), but no colorectal tumors were detected in non-Tg groups of SPF, and the tumor incidence was remarkably low in non-Tg-GB-4 mice. The tumor incidence and score in Tg- and non-Tg-GB mice varied depending on the bacterial combination in their intestine. These results indicate that the presence of human c-Ha-ras genes and intestinal bacteria substantially modify colorectal tumorigenesis induced by DMH.

1,2-Dimethylhydrazine↗
PubMed1998

Prevalence of "orphan" parvovirus infections in mice and rats.

"Orphan" parvovirus (OPV) infection in laboratory mice and rats was serologically surveyed for 465 mouse sera and 271 rat sera collected from 1986 to 1987 and from 1993 to 1996 in Japan. The results suggest that parvovirus infection is rare in mice but common in rats (positive rate: 13-22%) and that most putative viruses were OPVs. OPV is therefore considered to already have been harbored for at least ten years in Japan.

Animals↗
PubMed1998

A patient with Paget's disease of bone treated with etidronate disodium.

A 69-year-old Japanese woman was referred to our hospital because of abnormal skull X-ray findings. Serum total alkaline phosphatase, bone-specific alkaline phosphatase 3, osteocalcin and propeptide carboxyterminal of type I procollagen (PICP) levels were markedly elevated. Urinary excretion of hydroxyproline was also increased, suggesting that both bone formation and resorption were accelerated. Radiography of the skull showed "cotton wool" appearance. T1-enhanced MRI revealed that the skull-cap and diploe were swelled up. In 99mTc-MDP bone scintigraphy, all areas of the skull and a part of the right hemipelvis showed high uptake of the radioisotope. Based on the findings we made diagnosis of Paget's disease of bone which is a rare bone disorder in Japanese. Three-month oral administration of etidronate disodium resulted in normalization of serum PICP levels and urinary hydroxyproline excretion, whereas alkaline phosphatase levels were only partially lowered. Levels of the markers of bone turnover remained normal during a follow-up period of 3 months after the discontinuation of the treatment.

Aged↗
PubMed1998

Structural analysis of new antihypertensive peptides derived from cheese whey protein by proteinase K digestion.

Whey protein was digested with one of seven kinds of proteases at 37 degrees C (trypsin, proteinase K, actinase E, thermolysin, or papain) or at 25 degrees C (pepsin or chymotrypsin) for 24 h. The digested samples were assayed for the inhibitory activity of angiotensin-converting enzyme and for changes in the systolic blood pressure caused in spontaneously hypertensive rats after gastric intubation. The strongest depressive effect on the systolic blood pressure (-55 mm Hg) was observed at 6 h after gastric intubation of the whey protein that was digested by proteinase K. Finally, six peptides were chromatographically isolated from the proteinase K digest by a combination of hydrophobic reversed-phase HPLC and gel filtration. The amino acid sequences and their origins were clarified as follows: Val-Tyr-Pro-Phe-Pro-Gly [beta-casein (CN); f 59-64], Gly-Lys-Pro (beta 2-microglobulin; f 18-20), Ile-Pro-Ala (beta-lactoglobulin; f 78-80), Phe-Pro (serum albumin; f 221-222; beta-CN, f 62-63, f 157-158, and f 205-206), Val-Tyr-Pro (beta-CN; f 59-61), and Thr-Pro-Val-Val-Val-Pro-Pro-Phe-Leu-Gln-Pro (beta-CN; f 80-90). Chemical synthesis of these six peptides confirmed that all peptides, except an undecapeptide, have antihypertensive activity in spontaneously hypertensive rats. The synthetic tripeptide Ile-Pro-Ala, originating from beta-lactoglobulin, showed the strongest antihypertensive activity (-31 mm Hg).

Amino Acid Sequence↗
PubMed1998

Thermal inactivation analysis of mesophiles using the Arrhenius and z-value models.

The Arrhenius and z-value models were compared for thermal inactivation analysis of a mesophilic bacterium. The models produced a linear curve for the thermal inactivation data. Concerning the rate constant of inactivation, the D and k values predicted by the models at a constant temperature were similar. For extrapolated temperatures the z-value model predicted an insignificant decrease in the survival ratio compared to the Arrhenius model. The dynamic temperature survival curves predicted by the models were similar, and the models characterized the results. These results demonstrated that the models can be used for thermal inactivation analysis of mesophiles at various temperatures.

Escherichia coli↗