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Biomedical subjects

R Hara

Publications and source records attributed to R Hara.

At least 55 records · Page 3Linked to original sources

Fourier transform infrared spectroscopic study on retinochrome and its primary photoproduct, lumiretinochrome.

Structural studies of retinochrome, and its photoproduct, lumiretinochrome, were done by Fourier transform infrared difference spectroscopy. The absorption bands in the carbonyl stretching region which shift in D2O show the changes in the protein part during the photoreaction. Strong absorption bands in the finger-print region show that the all-trans-retinal chromophore in retinochrome isomerizes to the 11-cis-retinal chromophore in lumiretinochrome upon illumination with yellow-green light at 83K.

Animals↗

Studies on beta-lactam antibiotics. II. Synthesis and antibacterial activity of cephalosporins with substituted 1,3-dithietane directly attached to the C-3 position.

Preparation of cephalosporins bearing a 1,3-dithietane ring attached to the C-3 position using intramolecular rearrangement are described. The diastereoisomers (6a-I and 6a-II) were separated by silica gel column chromatography. These 3-[4-(carbamoyl carboxymethylene)-1,3-dithietane-2-yl]cephems showed comparable activity against Gram-negative bacteria to that of ceftazidime.

Cephalosporins↗

Studies on beta-lactam antibiotics. III. Syntheses and antibacterial activities of new 3-(1,3-dithiolan-2-yl)cephalosporins, YM-22508, YM-16457 and their prodrug-type esters.

The syntheses and biological activities of new 7-beta-[(Z)-2-(2-amino-4-thiazolyl)-2-hydroxy-iminoacetamido]-3-(1 ,3- dithiolan-2-yl)-3-cephem-4-carboxylic acid (YM-22508, 1a), 7-beta-[(Z)-2-(2-amino-4-thiazolyl)-2- methoxyiminoacetamido]-3-(1,3-dithiolan-2-yl)-3-cephem-4-carboxyli c acid (YM-16457, 1d) and their prodrug-type esters are described. Among them, YM-22561 (1c), the 1-acetoxyethyl ester of 1a, showed good in vivo efficacy in mice against infections of Staphylococcus aureus Smith, Streptococcus pyogenes S 23 and Escherichia coli NY-17 and a long plasma T1/2 in mice.

Animals↗

Cloning and nucleotide sequence of cDNA for retinochrome, retinal photoisomerase from the squid retina.

The Rhodopsin-retinochrome system is essential for the visual photoreception of molluscs. cDNA coding for retinochrome of the squid (Todarodes pacificus) was cloned and the nucleotide sequence has been determined. The sequence (2.1 kb) covers the whole coding region of 903 bp. The deduced primary sequence suggests that retinochrome contains seven transmembrane spanning domains. The homology with bovine rhodopsin and the possible retinal binding site are also discussed.

Amino Acid Sequence↗

[A case report of widely recurrent carcinoid tumor of the thymus].

We performed wide resection of recurrent carcinoid tumor of thymus. A 62-year-old male patient admitted to our department because of swelling of anterior chest wall. He had received extirpation of thymic carcinoid tumor 5 years ago and he was pointed out large mass formation in anterior mediastinum before admission. Wide resection of tumor including pericardium, chest wall, left lung and left brachiocephalic vein was performed. Left brachiocephalic vein was reconstructed and pericardium was replaced with Gore-Tex patch. The carcinoid tumor of thymus sometimes invade to adjacent organs and is apt to recur long time after first operation.

Carcinoid Tumor↗

Retinal-binding protein as a shuttle for retinal in the rhodopsin-retinochrome system of the squid visual cells.

The molluscan visual cell is characterized by having two photopigment systems, rhodopsin and retinochrome. In connection with these systems, located separately in the rhabdomal microvilli and in the nucleated cell bodies, the physiological role of retinal-binding protein (RALBP) was investigated in the squid (Todarodes pacificus) by using 3-dehydroretinal (retinal 2) as a tracer for retinal chromophore. In dark-adapted eyes, squid RALBP is combined abundantly with 11-cis-retinal. However, upon incubation with an excess of all-trans-retinal or retinol, RALBP took up great amounts of each of them, releasing its native retinoid ligands. When an all-trans-retinal-rich RALBP thus produced was incubated in the dark with metaretinochrome 2-carrying membranes, the RALBP released all-trans-retinal to the membranes to regenerate retinochrome, taking up 11-cis-retinal 2 from metaretinochrome 2. Upon further incubation of this 11-cis-retinal 2-rich RALBP with metarhodopsin-carrying membranes, the RALBP released the 11-cis-retinal 2 to the membranes to form rhodopsin 2, receiving all-trans-retinal from metarhodopsin. These findings show that squid RALBP is capable of serving as a shuttle during the recycling of retinal in the rhodopsin-retinochrome conjugate system to maintain the photoreceptive function of the visual cells.

Animals↗

Subacute toxicity of (-)15-deoxyspergualin in BALB/c mice. I. Hematological study.

(-)15-Deoxyspergualin (DSP), a bacterial metabolite obtained from Bacillus laterosporus, was shown to effectively suppress autoantibody production in mice and alloimmune reaction in mice and rats. Its potential toxicity and safety margin in BALB/c mice were studied by administering the drug, 0.5-5.0 mg/kg body weight, s.c., 6 days/week for 3 months. The animals were weighted every two weeks, and their blood was drawn for hematological and liver function studies. Control animals showed a gradual increase in body weight from 17.8 +/- 1.1 g (SD) to 20.2 +/- 3.2 g during the 3 months of treatment. The body weight of 0.5 mg- and 2.5 mg-DSP group was not significantly different from that of the control group. In contrast, 5.0 mg-DSP group of animals showed significant decrease in their weight compared with the control after 5 weeks of treatment (P less than 0.01). They were then sacrificed. WBC in 0.5 mg-, 2.5 mg- and 5.0 mg-DSP groups were significantly lower compared with the control after 3 months of treatment. On the other hand, only 5.0 mg-DSP group showed significantly lower level in their RBC, Hb and Hct values (P less than 0.05). In contrast, platelet counts in 2.5 mg- and 5.0 mg-DSP group significantly increased. No manifest effect due to DSP on differential count of leukocytes was observed, although on day 92, a significant difference was shown in the stab cells of the 0.5 mg-DSP group and in the eosinophils in the 2.5 mg-DSP.(ABSTRACT TRUNCATED AT 250 WORDS)

Alanine Transaminase↗

Subacute toxicity of (-)15-deoxyspergualin in BALB/c mice. II. Histopathological study.

Following the preceding report on hematological aspects in subacute toxicity of (-)15-deoxyspergualin (DSP), the present report dealt with the histopathological changes produced by DSP, 0.5-5.0 mg/kg, given to BALB/c mice for three months. At sacrifice, various internal organs such as heart, lungs, liver, spleen and kidneys, were taken, and their wet weights immediately measured. HE- or PAS-stained sections were histopathologically studied under light microscope. Additionally, frozen sections of the spleen were prepared to evaluate the effect of DSP on the lymphocyte surface markers like thy 1 and B220 by avidin-biotin complex (ABC) technique. Although the mean weights of lungs, liver, spleen and kidneys in the 0.5 mg- and 2.5 mg-DSP groups were not significantly different from those in the control animals, the weights of the heart, lungs, liver and spleen in the 5 mg-DSP group were significantly lower. Histopathological studies by light microscopy revealed no abnormalities in the heart, lungs, liver or kidneys taken from the mice given 0.5-5.0 mg/kg DSP. In contrast, significant changes were observed in the spleen and bone marrow of the 5.0 mg group of mice. Likewise, in the intestine of the 0.5-5.0 mg groups dose-dependent lesions, such as degeneration or disappearance of the mucosal epithelium, infiltration by inflammatory cells, and pseudo-membrane formation, was observed. By ABC technique, preferential decrease of B cells was seen in the splenic corpuscles of the DSP-treated mice. Histopathological changes due to DSP predominantly seen in the lymphoid and/or hematopoietic organs may be directly related to the immunosuppressive potency inherent to this drug.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

IRBP-like proteins in the eyes of six cephalopod species--immunochemical relationship to vertebrate interstitial retinol-binding protein (IRBP) and cephalopod retinal-binding protein.

SDS polyacrylamide gel electrophoresis and immunoblotting were used to examine soluble proteins from the eyes of six species of cephalopods i.e. Lolliguncula brevis, Sepia officinalis, Octopus maya, Octopus bimaculoides, Rossia pacifica and Loligo opalescens. All species had a protein ("IRBP") with molecular weight virtually identical with vertebrate interstitial retinol-binding protein (IRBP) averaging 132,400 +/- 700 (n = 6). "IRBP" reacted on nitrocellulose blot transfers with rabbit antibovine IRBP and rabbit antifrog IRBP antibodies. Unlike vertebrate IRBP, cephalopod "IRBP" (from L. brevis) did not bind exogenous retinol or concanavalin A. The N-terminal amino acid appeared to be blocked in samples electroeluted from SDS gels. The antifrog IRBP antibodies also reacted with a series of proteins with molecular weights between 46,000 and 47,000, identified as retinal-binding protein (RALBP) with anti-RALBP antibodies. Anti-IRBP also reacted with pure RALBP prepared from Todarodes pacificus. Occasionally, anti-RALBP antibodies were seen to react weakly with "IRBP" in some cephalopods. We conclude that RALBP, cephalopod "IRBP" and vertebrate IRBP share a common but distant ancestry, and that a protein resembling IRBP appeared before the vertebrates diverged from the invertebrates. Both RALBP and IRBP appear to have analogous functions in shuttling retinoids between rhodopsin and the corresponding isomerizing system, retinochrome in the cephalopods and retinol isomerase in the vertebrates. The function of cephalopod "IRBP" is unknown.

Amino Acids↗

Isolation and characterization of a retinal-binding protein from the squid retina.

A retinal-binding protein (RALBP) was isolated from the squid retina, and purified by anion-exchange and size-exclusion chromatography. The molecular weight was determined to be 51,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by gel filtration. The purified sample showed absorption maxima at about 330 and 400 nm in addition to a protein band, indicating the occurrence of retinol and retinal, respectively. The relative heights of these two peaks varied from preparation to preparation, depending on retinoid ligands. Irradiation of RALBP caused no marked change in absorption, but the amount of 11-cis-retinal decreased to form a photosteady state mixture with all-trans- and 13-cis-retinals. RALBP was fairly stable even in the presence of hydroxylamine (100 mM), but was affected by sodium borohydride (30 mM) or borane dimethylamine (400 mM), with the retinal reduced to retinol. When incubated with metaretinochrome-carrying membranes in the dark, RALBP specifically took up 11-cis-retinal and lost all-trans-retinol. Upon further incubation of this RALBP with opsin-containing membranes, rhodopsin was progressively formed in the dark. Squid RALBP may act as a shuttle in transferring the 11-cis-retinal from metaretinochrome to opsin in the visual cells.

Animals↗

Studies on beta-lactam antibiotics. I. Synthesis and in vitro anti-pseudomonal activity of 3-isothiazole-cephalosporin derivatives.

The synthesis and in vitro activity of 7 beta-[(Z)-2-(2-amino-4-thiazolyl)-2-(2-carboxy-2- alkoxyimino)acetamido]cephalosporins with a (4-carboxy-3-hydroxy-5-isothiazolyl)thiomethyl group at the 3-position are described. These cephalosporins (9a approximately 9i) showed excellent activity against Gram-negative bacteria including beta-lactamase producing strains. The most interesting compound of the series was 7 beta-[(Z)-2-(2-amino-4-thiazolyl)-2- (2-carboxy-2-propoxyimino)acetamido]-3-cephem-4-carboxylic acid (9g, YM-13115) because of its outstanding inhibitory potency against Pseudomonas aeruginosa and highly prolonged plasma half-life in rats.

Anti-Bacterial Agents↗

Rhodopsin and retinochrome in the retina of a marine gastropod, Conomulex luhuanus.

Photopigments in the conch retina were examined with special attention given to the photic vesicles characteristic of gastropod photoreceptors. Three different fractions of visual cell fragments were prepared from the retina: the MV-fraction containing the rhabdomal microvilli, and the PVH- and PVL-fractions containing the photic vesicles located in the visual cell body. Rhodopsin was found in the MV-fraction (lambda max = 474 nm), and yielded a photoequilibrium mixture with metarhodopsin (lambda max = 512 nm) on irradiation with blue light. Retinochrome was found in both of the PVH- and PVL-fractions (lambda max = approximately 510 nm), and was bleached into metaretinochrome by exposure to orange light, showing no marked shift of the absorption peak. Unlike the PVH-fraction, the PVL-fraction contains much aporetinochrome in addition to retinochrome, suggesting that the large mass of photic vesicles around the nucleus may serve as storage for retinal in retinochrome and for newly synthesized aporetinochrome. The total amount of retinochrome in the retina was several times higher than that of rhodopsin, distinguishing the gastropod eye from the cephalopod eye.

Animals↗