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Biomedical subjects

T Iwasa

Publications and source records attributed to T Iwasa.

At least 19 recordsLinked to original sources
PubMed1994

Phylogenetic relationships among vertebrate visual pigments.

Genomic DNA fragments in exon 4 of chicken, goldfish and salmon visual pigments were amplified by polymerase chain reaction, using oligonucleotide mixtures as primers, and hypothetical phylogenetic trees were drawn up from the deduced amino acid sequences. The results suggest that vertebrate visual pigments have evolved along at least five lines, and that these lines diverged from an ancestral gene before the bony fishes diverged from the rest of the higher vertebrates.

Amino Acid Sequence↗
PubMed1994

The biological significance of glycyrrhizin- and glycyrrhetinic acid derivative-induced selective phosphorylation of histones H2A and H2B by A-kinase in vitro.

Histones H2A and H2B were found to be glycyrrhizin (GL)-binding proteins, because (i) the two histones H2A-H2B pairs were isolated selectively from the crude histone preparations of calf thymus by means of GL-affinity column chromatography (HPLC); (ii) phosphorylation of these two histones by A-kinase was remarkably stimulated by native GL or oGA (a derivative of glycyrrhetinic acid) at 20 microM; and (iii) in the crude histone preparations of calf thymus, these two histones were selectively phosphorylated by A-kinase in the presence of both dsDNA and 20 microM oGA or 20 microM GL. The provided data suggest that the GL-induced selective phosphorylation of histones H2A and H2B by A-kinase may be implicated in the transcriptional activation involved in the biological activities of the drug.

Animals↗
PubMed1993

GTP-binding protein couples with metabotropic glutamate receptor in bovine retinal on-bipolar cell.

GTP-binding protein (G protein) linking to metabotropic glutamate receptor of bovine retinal on-bipolar cell was studied by use of pharmacologically selective ligands, 2-amino-4-phosphonobutyric acid (APB) on bacterial toxin-catalyzed ADP-ribosylation and GTP gamma S-binding. In contrast to the electrophysiological findings reported, G protein coupling to APB-sensitive glutamate receptor served as a substrate for pertussis toxin but did not for cholera toxin. Several glutamate analogues effective on on-bipolar cell, as well as APB, increased GTP gamma S binding to retinal membranes devoid of rod outer segments. The enhancement of GTP gamma S binding by APB was completely abolished when the membranes were pretreated with pertussis toxin and NAD. These results suggest that, in retinal on-bipolar cell, the G protein which couples metabotropic glutamate receptor to hyperpolarizing response of the cell is sensitive to pertussis toxin.

Animals↗
PubMed1993

Infrared studies of octopus rhodopsin. Existence of a long-lived intermediate and the states of the carboxylic group of Asp-81 in rhodopsin and its photoproducts.

The infrared absorption spectra of octopus rhodopsin and its photoproducts have been observed at 282K and 210K under irradiation of blue and orange light in a neutral condition. The acid metarhodopsin-minus-rhodopsin and lumirhodopsin-minus-rhodopsin difference spectra have been obtained. A new intermediate (called transient acid metarhodopsin) with a lifetime of about 5 s has been found to exist prior to acid metarhodopsin. The present results, together with the data obtained previously, give information on the state of the carboxylic group in the side chain of Asp-81, which is the only acidic amino-acid residue in the part of opsin buried inside the membrane. This carboxylic group is protonated throughout the transformation series, but its state changes on going from transient acid metarhodopsin to acid metarhodopsin. It is probable that these two photoproducts are different from each other only in the opsin moiety.

Animals↗
PubMed1993

Primary neurilemoma of the thyroid gland: report of a case.

Neurilemoma, like other non-epithelial tumors, seldom occurs in the thyroid gland. A 57-year-old man was first referred to our hospital with an asymptomatic anterior neck tumor. A solid tumor was detected in the right lobe of the thyroid and an enucleation of the thyroid tumor was performed. The tumor was 35 x 33 x 33 mm in size, and diagnosed as Antoni A type neurilemoma. We were only able to find seven previously reported detailed cases of primary neurilemoma of the thyroid gland. A review of these cases, however, revealed that neurilemoma tends to develop in the right lobe of the thyroid gland. An operation is thus considered necessary and an enucleation of the tumor is appropriate.

Humans↗
PubMed1993

Submassive hepatic necrosis induced by dichloropropanol.

A hitherto undescribed industrial liver injury of fulminant form induced by dichloropropanol is reported. Two middle-aged men developed severe hepatic injury just after cleaning a dichloropropanol tank at a plant producing dichloropropanol. They died from hepatic failure 4 and 11 days respectively, after carrying out the work. Liver specimens taken at autopsy from one of the cases showed submassive hepatic necrosis. This accident prompted us to undertake an experimental study in rats of intraperitoneal one-shot injection of two isomeric substances of dichloropropanol, that is, 2,3-dichloro-1-propanol (DC1P) and 1,3-dichloro-2-propanol (DC2P). Saline was injected into the control rats. One, two, four, six, 24, 48, 72 h, and 1 week after the injection, rats in each group were sacrificed. Neither control nor DC1P-injected rats showed significant biochemical or histopathological abnormalities. DC2P-injected rats revealed elevations of transaminase from 6 h after the injections, and submassive necrosis of the liver was observed in many rats. It was concluded that the severe liver injuries in both the human cases and rats in our study were caused by DC2P.

Adult↗
PubMed1993

Reduction of leaky lymphocyte clones producing immunoglobulins and thymic lymphocytic leukemia by selective inbreeding of SCID (severe combined immunodeficiency) mice.

Selective inbreeding of C.B17-scid/scid mouse pairs showing undetectable IgG and IgM has been carried out in order to reduce the mortality of mice by early occurrence of thymic lymphocytic leukemia and abnormal lymphocyte clones producing immunoglobulins, both of which inhibit the successful heterotransplantation of normal and neoplastic human tissues. Although the majority of C.B17-scid/scid mice showed undetectable (< 1 microgram/ml) or low level (< or = 25 micrograms/ml) of serum IgG and IgM, some produced abnormally high concentrations of IgG and IgM (> 25 micrograms/ml). The incidence of such mice showing higher levels of IgG was very high at F1 and F2 generation (10/55, 18.2%), but significantly low after the F3 generation (18/446, 4.0%, p << 0.001). Although leukemia incidence was very high at F4 to F5 generations (8/40, 20.0%), death from leukemia was not observed early in life (4-6 months after birth) at F7 to F10 generations (0/36, 0%, p < 0.01) and was very low during the age of 6-10 months after the F8 generation (11/66, 16.7% at F4 and F5 vs 4/93, 4.3% at F8-10), p < 0.01). Scid mice improved by the selective inbreeding will provide an invaluable experimental system for the heterotransplantation of normal and neoplastic human tissues.

Animals↗
PubMed1993

[Brachial plexus block with a nerve stimulator and "around the needle" catheter technique].

Brachial plexus block using a nerve stimulator is an accurate procedure. But prolonged analgesic effect can not be obtained. Therefore we used "around the needle" catheter technique to have a long analgesic effect. A 20-gauge, 5-inch intravenous catheter (Angiocath) was threaded over a 23-gauge, 10-cm needle (Pole). We used axillary approach. The cathode of the nerve stimulator (NS-2CA, Professional Instrument company) is connected to the needle, and its anode is connected to the electrode on the surface of the skin. When the needle is introduced and advanced, 1 mA of electric current is applied for nerve stimulation. When the muscle twitch is obtained, a plastic cannula is then threaded off the needle into the axillary sheath. An infusion tube and three way stopcock is connected to the cannula. From 1988 to 1991 we had 31 cases. The success rate is about 90%. If we stimulate other nerves in the same sheath, it is not necessary to seek aimed one. But the musculocutaneous nerve is the only exception, because it may be stimulated outside the neurovascular sheath.

Brachial Plexus↗
PubMed1992

[Fulminant hepatitis after the inhalation of dichloropropanols].

A fatal case of acute fulminant hepatitis following exposure to dichloropropanols is reported. A 59-year-old male worker in a chemical plant developed general malaise, nausea and vomiting several hours after cleaning a tank that had contained dichloropropanols. He had no previous history of hepatic dysfunction. On admission, hepatomegaly was prominent. Because of highly elevated levels of GOT and GPT in the serum, reduced prothrombin time and a lowered consciousness level, a diagnosis of fulminant hepatitis was made. Significant decreases of leukocytes and platelets were also observed. Serum creatinine and BUN were slightly elevated. Although plasma exchanges were conducted on the third and fourth day, the liver functions continued to deteriorate. The patient died on the fifth day. Because dichloropropanols could be detected in the blood specimens obtained at the time of admission, we considered that fulminant hepatitis in this case was attributed to dichloropropanols exposure. To our knowledge, this is the first case of fulminant hepatitis after dichloropropanols-exposure.

Administration, Inhalation↗
PubMed1992

[Toxicity of dichloropropanols--changes in hematological findings and serum chemistry].

We investigated the toxicity of dichloropropanols (DCPs) in hematological findings and serum chemistry. The solutions of two isomers of DCPs, 1,3-dichloro-2-propanol (DC2P) and 2,3-dichloro-1-propanol (DC1P) were dissolved in saline at the concentration of 100 mg/ml, and 0.1 ml of each solution was subcutaneously injected into male Wistar rats weighing about 200 g. At 6 hours after the injections, in the DC2P group, the number of white blood cells and platelets showed a significant decrease. Transaminases, alkaline phosphatase and lactate dehydrogenase were greatly elevated. Blood urea nitrogen and creatinine also showed a significant increase. There were no changes in the measurements in the DC1P group. These results indicate that there is a prominent hepatotoxicity in DC2P, and that there is a considerable difference in the toxicity present in DC2P and DC1P. Furthermore, in the workplace where DCPs, especially DC2P, is used, the monitoring of the working environment and biological monitoring should be mandatory.

Alkaline Phosphatase↗
PubMed1992

Artificial pigments of halorhodopsin and their chloride pumping activities.

Halorhodopsin (HR), the light-driven chloride pump of Halobacterium halobium, was bleached with hydroxylamine and regenerated with all-trans-retinal under several different conditions. The largest recovery of the pigment was found with apoprotein obtained from detergent-free HR [HR(BB)]. To compare the chloride-pumping mechanism of HR with that of bacteriorhodopsin (BR; the light-driven proton pump of the same bacteria), HR pigment analogues were reconstituted with the bleached HR (BB) and retinal analogues. The corresponding BR pigment analogues have previously been shown to have little or no proton-pumping activity, except for retinal2 (3,4-dehydroretinal). Pigment analogues with 13-demethylretinal or retinal2 showed an "opsin shift" similar to that of the all-trans-retinal pigment of both HR and BR. Opsin shifts of the pigments of 9-12-phenylretinal and 3,7-dimethyl-2,4,6,8-decatetraenal and haloopsin are slightly different from those of the corresponding BR pigment analogues, presumably reflecting differences of the chromophoric structures in HR and BR. In addition to the spectral properties, the effect of chloride ion on deprotonation of the Schiff base was measured. These pigment analogues showed the "chloride effect" (a shift of the pK value for deprotonation of the Schiff base), but a smaller one than that seen in HR. For a measurement of the chloride-pumping activity, each retinal analogue was added to a culture of L07 cells (BOP-, HOP+, Ret-), and the activity was measured with the cell suspension. Only cultures with retinal or retinal2 showed chloride-pumping activity, as is true for proton pumping by BR. This suggests that a similar retinal-protein interaction is necessary for both ion pumps.

Bacteriorhodopsins↗
PubMed1992

Isolation rates and pathogenicity of enterococci in obstetric and gynecological operations.

Isolation of enterococci in patients undergoing obstetric and gynecological operations was studied as well as reviewing the postoperative infection due to this organism during the period from 1985 to 1990. 1) In 126 cases undergoing abdominal total hysterectomy, vaginal specimens were obtained before and after (3rd day) the operation. The isolation rates increased after the operation (before 16.7%, after 35.7%). They increased not only in the group using PIPC, CEZ, CEPR, CMZ, and LMOX by drip infusion but also in the group without prophylactic use of antibiotics. On the other hand in the group using CP vaginal suppositories, the isolation rate decreased. However no statistical proof was obtained as to antibiotics especially in regard to cephem drugs as the reason for the increase. 2) Enterococci were isolated from the surgical field during abdominal total hysterectomy in only 2.0% (n = 88). 3) Isolation rates of enterococci inside the transvaginal drain following radical hysterectomy (n = 30) reached 86.7%. 4) E. faecalis was isolated in 20.0% of the cases with wound infection (n = 25). However isolated Enterococcus strains were not regarded to be the causative organism. 5) There was one case of postoperative enterococcal septicemia in treating stage Ib adenocarcinoma of the uterine cervix.

Anti-Bacterial Agents↗
PubMed1992

Production and biological activities of a new antifungal antibiotic, TAN-950 A.

A novel antifungal antibiotic, TAN-950 complex, was isolated from the culture filtrate of Streptomyces platensis A-136 (IFO 14603, FERM BP-1786). The water-soluble amphoteric substances in this complex were purified by chromatography using ion-exchange resins, QAE-Sephadex and adsorptive resins and were designated TAN-950 A and TAN-950 A-E mixture. The molecular formula of TAN-950 A was determined to be C6H7N2O4Na for the sodium salt. This new amino acid antibiotic showed antifungal activity against Candida albicans in vitro and in vivo, and had low toxicity in mice.

Animals↗
PubMed1991

Isolation and characterization of lamprey rhodopsin cDNA.

Genomic DNA fragments coding a visual pigment of the lamprey were amplified by polymerase chain reaction, using oligonucleotide mixtures as primers. The complete coding region of the cDNA was obtained by separate amplification of both cDNA ends. The deduced amino acid sequence of the coding region showed 78-82% identity with those of rhodopsins of higher vertebrates, but only 43-47% identity with those of human color pigments. The cloned DNA appears to be the cDNA of a lamprey rhodopsin, which is expressed in the "short" photoreceptor cell.

Amino Acid Sequence↗
PubMed1990

Cloning of cDNA and amino acid sequence of one of chicken cone visual pigments.

The chicken has four kinds of color visual pigments, in addition to rhodopsin. A chicken genomic DNA library was screened with cDNA of human red-sensitive pigment and a chicken genomic DNA fragment including rhodopsin exons 2, 3 and 4, and then a genomic DNA fragment encoding a visual pigment, possibly an iodopsin, was cloned. A cDNA library, constructed from chicken retina mRNA, was screened with the genomic DNA fragment and the cDNA of human red-sensitive pigment, and the cDNA encoding the pigment was cloned. The nucleotide sequence of this cDNA was similar to that of the human red-sensitive pigment, with identities of 78% for the nucleotide sequence and 84% for the amino acid sequence with human red-sensitive pigment.

Amino Acid Sequence↗
PubMed1990

[A serous cystadenoma of the ovary of borderline malignancy with a fifteen-year history. A case report].

A case of a serous cystadenoma of a ovary of borderline malignancy is reported. Sixteen years earlier, the patient had undergone an exploratory laparotomy because of ovarian tumor, and the histologic diagnosis had been a serous cystadenocarcinoma. Postoperative chemotherapy was not effective and drainage of the tumor fluid had been performed for 15 years, with the estimated drainage volume estimated to have reached, 1,000 1. Gradual malnutrition and marked tumor growth then become apparent. A reevaluation of the initial histologic slides and her clinical course strongly suggested a serous cystadenoma of borderline malignancy. Thus a tumor resection, a bilateral salpingo-oophorectomy, and a hysterectomy was performed. A histologic diagnosis of a resected specimen confirmed a serous cystadenoma of borderline malignancy and the histologic features were quite similar to those of the initial biopsy specimens. The patient is living well postoperatively for 8 months without postoperative chemotherapy.

Adult↗