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Biomedical subjects

A Murakami

Publications and source records attributed to A Murakami.

At least 253 records · Page 14Linked to original sources
PubMed1993

X-arrestin: a new retinal arrestin mapping to the X chromosome.

We have been using a differential cDNA cloning approach to isolate human retina-specific and retina-enriched genes [1]. A 1,314 bp cDNA was isolated by this approach, representing a highly retina-specific message encoding a 388 amino acid protein showing 58%, 50%, and 49% homology to bovine beta-arrestin, and bovine and human retinal arrestin (S-antigen), respectively. Chromosomal mapping localized this new arrestin gene to the proximal long arm of the X chromosome, hence it was named X-arrestin. In situ hybridization demonstrated its expression in the inner and outer segments and the inner plexiform regions of the retina.

Amino Acid Sequence↗
PubMed1993

Esophageal cancer associated with multiple cancerous lesions: clinicopathologic comparisons between multiple primary and intramural metastatic lesions.

Detailed histopathological examination of serial blocks and subserial sections of the entire resected esophagus in 111 patients who underwent esophagectomy for esophageal squamous cell carcinoma revealed 38 associated cancerous lesions apart from the main tumors, in 33 patients (29.7%). These associated lesions were divided into multiple primary lesions (MPLs; 27 lesions in 23 patients) and intramural metastatic lesions (IMLs; 11 lesions in 10 patients). Thirteen and fourteen MPLs were distributed on the proximal and distal sides, respectively, of the main tumor with the same mean distance of 2.6 cm. Three and 8 IMLs were located on the proximal and distal sides, respectively, with mean distances of 3.4 cm and 4.6 cm. With respect to the histological depth of cancer invasion, MPLs were all confined within the submucosal layer (superficial cancer) while IMLs varied from the submucosa to the adventitia. Histological findings indicate that MPLs may be associated with a possible increased multicentric carcinogenic potential in the non-cancerous epithelium of the esophagus of patients who have had an antecedent esophageal cancer, and that IMLs are developed by intramural lymphatic spread from the primary esophageal cancer. These results emphasize the need for careful attention to the choice of margins during the surgical resection of the esophagus.

Aged↗
PubMed1993

Regulation of nerve growth factor secretion in L-M cells by catechol derivatives.

We investigated the mechanism responsible for the stimulation of nerve growth factor (NGF) secretion by catechol derivatives in L-M cells, using L-threo-3,4-dihydroxyphenylserine (L-DOPS). Treatment of the cells with L-DOPS increased the NGF content in the L-M cell medium by approximately 3-fold. This stimulatory effect was not blocked by a decarboxylase inhibitor, or by alpha- or beta-adrenergic blockers. Intracellular cAMP levels were not changed by exposure to L-DOPS. The antioxidants, ascorbic acid and sodium pyrosulfite, completely prevented the stimulatory effect of L-DOPS, and radical scavengers (superoxide dismutase plus catalase) caused a significant partial inhibition of the response to L-DOPS. Quinone derivatives (adrenochrome, 4-n-propyl-1,2-benzoquinone), which are the oxidative products of the catechol derivatives, increased the NGF content in the medium, and their potency was greater than that of the catechol derivatives themselves. These findings suggest that L-DOPS and other catechol derivatives might be oxidized in the medium to form quinone derivatives, and that it is these which predominantly express a stimulatory effect on NGF secretion by a novel cAMP-independent mechanism in L-M cells.

Animals↗
PubMed1993

Characterization of mammary plaques in DDD mice congenic for Mtv-2 gene, DDD/1-Mtv-2/Mtv-2.

DDD/1 mice free from exogenous mouse mammary tumor virus (MMTV) do not develop any neoplastic mammary lesions. In GR mice, the expression of Mtv-2, an endogenous proviral MMTV, leads to 100% incidence of mammary ductal hyperplasias and tumors. An Mtv-2 congenic line, DDD/1-Mtv-2/Mtv-2, was established by introducing Mtv-2 from GR into DDD/1 to elucidate its function. Development of mammary plaques (MPQ) characterized by ductal hyperplasias was investigated in 152 congenic females on day 17 to 19 of the first pregnancy. The incidence of MPQ was 48.0% and most MPQ-positive mice (75.3%) had only one MPQ. Generally, MPQ were small in size: the diameter was as small as < or = 3 mm in 77.6% of them. Of 84 MPQ implanted into intact fat pads, 43 (51.2%), 38 (45.2%) and 3 (3.6%) showed undetectable, pregnancy-dependent and autonomous growths; respectively when the hosts underwent pregnancy. Almost all MPQ produced normal-appearing ductal-alveolar outgrowths in mammary epithelium-divested or cleared fat pads of virgins. MPQ implanted into cleared fat pads were very similar to normal mammary glands in the responses to progesterone (P) and estradiol (E) alone or in combination except for association of ductal hyperplasias in 4 of 12 MPQ under E+P treatment. These findings revealed the preneoplastic nature of MPQ. Exogenous MMTV proviruses were demonstrated in all MPQ. The int-2 DNA rearrangement was found in 2 of 10 MPQ but in none of 9 mammary carcinomas and the int-1 DNA rearrangement in none of 10 MPQ but in 5 of 10 carcinomas. It is thus likely that the Mtv-2 gene participates in a very early stage of mammary tumorigenesis not directly but indirectly through insertion mutation of host genes, while the cellular oncogenes, int-2 and int-1, may contribute to preneoplastic transformation of mammary epithelium and progression from preneoplastic to more malignant states, respectively.

Animals↗
PubMed1993

International cooperation of Japanese pediatricians with Cairo University Pediatric Hospital.

In connection with 'Child Year' in 1980, an agreement on the construction and donation of a pediatric hospital was concluded between the Egyptian and Japanese Governments. Under this agreement, the Cairo University Pediatric Hospital (CUPH) was opened in March 1983, as a four-storey building with 240 beds, and including four operating rooms, an intensive care unit (ICU) and neonatal ICU. The technical cooperation and supply of medical equipment in all areas of CUPH is ongoing during this project. The subject matter of technical cooperation is as follows. (1) Dispatch of Japanese experts to Egypt for short and long terms. (2) Acceptance of Egyptian trainees to Japan. (3) Supply of medical equipment and materials. Through the first 5 years of this cooperation, the management of ICU, operating theaters, medical and surgical wards has improved markedly with great efforts from the Egyptian and Japanese staff. Based on this successful cooperation, the Pediatric Cardiovascular Center was established in 1988 with a two-storey extension in the hospital including two cardiac operation theaters, ICU and other special facilities. Now, CUPH has become the center of pediatric medical care in not only Egypt but also the surrounding Arabic countries, supported by the friendly and close relationship between Egypt and Japan.

Child↗
PubMed1993

Mouse mammary tumor virus with rearranged long terminal repeats causes murine lymphomas.

Mouse mammary tumor virus (MMTV) is a slowly transforming retrovirus associated primarily with the induction of mammary tumors. It is widely accepted that T-cell lymphomas of various mouse strains are associated with extra proviruses of MMTV. These extra proviruses showed site-specific rearrangements in the U3 region of long terminal repeats (LTRs), consisting of about 400 nucleotide deletions and occasional substitution resulting in unique tandem repeats. However, the question of whether these mutant MMTVs cause lymphomas has not been experimentally resolved. Here we present distinct evidence that they do. We constructed chimeric MMTVs by replacing the LTR of the recently constructed pathogenic MMTV provirus clone with rearranged LTRs of MMTV proviruses obtained from two DBA/2 mouse lymphoma cell lines, MLA and DL-8, and inoculated them into BALB/c mice. These mice developed lymphomas, but no mammary tumors, 4 to 11 months postinoculation, whereas the original pathogenic MMTV clone alone induced mammary tumors. These results showed that the tissue specificity of MMTV tumorigenesis is determined by the LTR structures.

Animals↗
PubMed1993

Detection of specific base sequences in solution using DNA probes labeled with d- and/or 15N-substituted spin-labels.

In order to enhance the sensitivity and the accuracy of the detection by the DNA probe method in which spin-labeled oligonucleotides are used as probes, 4-amino-2,2,6,6-tetramethylpiperidine-15N-oxyl-d16 (4-amino-TEMPO-15N-d16) and 4-amino-2,2,6,6-tetramethylpiperidine-14N-oxyl-d16 (4-amino-TEMPO-14N-d16) were incorporated into the phosphate linkage of oligonucleotides by the hydrogen phosphonate method and these DNA probes were used for the detection of target DNAs in solution. The intensities of the electron paramagnetic resonance (EPR) signals of the oligonucleotides labeled with 4-amino-TEMPO-14N-d16 and 4-amino-TEMPO-15N-d16 were 3-fold and 4-fold larger than that of the oligonucleotide labeled with 4-amino-TEMPO-14N, respectively. Also, the EPR lines of these labeled oligonucleotides do not overlap each other, allowing the detection of two different regions in the same target DNA by the single EPR measurement.

Base Sequence↗
PubMed1993

Oligonucleotides site-specifically spin-labeled at 5'-terminal or internucleotide linkage and their use in gene analyses.

Spin-labeled oligonucleotides (S-probes) were synthesized and examined as DNA probes to monitor hybrid formation. TEMPO was introduced either at the internucleotide linkage of 5'-terminus (Type 1) or at the 5'-terminal hydroxyl group (Type 2) and both types of S-probes were used in this study. The presence of target DNA was detected in solution by EPR spectroscopy for both types of S-probes. Hybridization of the S-probes resulted in notable broadening of EPR line width, accompanied by a decrease in the EPR signal height ratio for I(-1)/I(0).I(-1)/I(0) of S-probes having no spacer between oligonucleotide and TEMPO decreased more markedly than that of S-probes with a spacer, indicating that TEMPO should be introduced to an oligonucleotide directly to monitor hybrid formation. When M13mp8 single-stranded DNA with or without an EcoRI recognition site was selected as a target DNA, hybrid formation was detected only for DNA containing EcoRI site in solution using spin-labeled oligonucleotides.

Bacteriophage M13↗
PubMed1993

Effective inhibition of hydroxyl radicals by hydroxylated biphenyl compounds.

In aqueous media, approximate rate constants for the reactions between hydroxyl radicals (.OH) and biphenyl compounds such as dehydrodieugenol, magnolol, honokiol, dehydrodidihydroeugenol, dehydrodivanillyl alcohol, and dehydrodicreosol were estimated by competition reactions for .OH between these biphenyls and 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). By measuring the decrease in the height of the EPR signals of the .OH spin adduct, rate constants in the order of 10(9) to 10(10) M were measured.

Biphenyl Compounds↗
PubMed1993

Loop-like structure of dGTTG in solution.

A strong NOESY cross peak was observed between G1H8 and G4H8 for a single-stranded tetradeoxyoligonucleotide dGTTG in aqueous solution. If dGTTG is in an expanded form, NOE should not be observed because the distance between G1H8 and G4H8 is estimated to be about 13 A. This NOESY cross peak shows that the guanine residues of the both ends of dGTTG exist with short distance (< 5 A), and that dGTTG has a distorted loop-like structure in aqueous solution. This is the shortest single-stranded oligodeoxynucleotide that has a rigid structure in solution.

Magnetic Resonance Spectroscopy↗
PubMed1993

Mechanistic aspects of the interaction of antisense DNA.

To investigate the mechanism of antisense effects, diastereoisomerism of oligodeoxynucleotides with modified internucleotide phosphate linkages such as oligodeoxynucleoside phosphoramidates (OPA) and oligodeoxynucleoside phosphorothioates (OPT). Reversed-phase HPLC was used to separate the diastereoisomers of OPA (up to tetramer) and OPT (up to pentamer), and it was found that the complete purification of all diastereoisomers could be achieved by the two-step chromatographic approach. From the circular dichroism measurements, it was found that some diastereoisomers formed certain hybrids with their complementary oligonucleotides and some did not.

Chromatography, High Pressure Liquid↗
PubMed1993

[Acute aortic dissection due to cross-clamp injury during coronary artery bypass grafting--a report of successfully repaired case].

A case with successfully repaired acute aortic dissection due to cross-clamp injury during coronary bypass surgery was reported. A 54-year-old man had usual coronary artery bypass surgery by using 3 saphenous vein grafts (4 distal anastomosis). Immediately after the completion of cardiopulmonary bypass, acute aortic dissection, which was caused by aortic cross-clamp, was noted. Cardiopulmonary bypass was resumed and the injured ascending aorta was replaced with prosthetic graft under profound hypothermia and circulatory arrest. An "Island flap" of the ascending aorta (3 x 4 cm in diameter), containing 3 proximal anastomotic positions of vein grafts, was excised from the aortic wall, and was re-implanted into the frontal wall of the aortic prosthesis. The patient well tolerated the operative procedure, and fully recovered from the serious condition after 6 days of IABP support and 11 days of inotropic support. He is doing quite well one year after the surgery. This case is believed to be the first reported one of such reconstructive method for acute aortic dissection during the coronary bypass surgery.

Acute Disease↗
PubMed1993

[Single selective cerebral perfusion for aortic arch replacement].

The patients underwent aortic arch replacement for aneurysmal disease from 1988 to 1993 using a simplified cardiopulmonary bypass (CPB) technique with single selective cerebral perfusion (single SCP). Recently cold cerebral perfusion technique was also used. In order to study the effect of this technique, we monitored bilateral carotid artery pressure, blood oxygen saturation of jugular vein and brain oxygenation by near infrared spectroscopy during CPB. Of the ten patients with arch aneurysm, five had urgent operation for ruptured aneurysm. The cold single SCP was accomplished by perfusion to the right axillary artery using separate pump and separate heat exchanger (flow 10-15 ml/kg/min, pressure 40-60 mmHg, perfusion temperature under 12 degrees C) under the low CPB flow (1,000-1,500 ml/min), moderate systemic cooling (23-25 degrees C) and retro-grade cardioplegia. There were no strokes caused by this technique. This simplified technique of cold single SCP was simple and attractive method, provide satisfactory cerebral protection.

Aged↗
PubMed1992

Isolation of human retinal genes: recoverin cDNA and gene.

A human retina cDNA library enriched for retina-specific clones was prepared by subtraction with a non-retina population of cDNA in combination with polymerase chain reaction (PCR) amplifications. A highly retina-specific cDNA clone (1190 bp) was obtained through this library encoding a 200 amino acid protein with three calcium binding sites and 87% homology to the bovine photoreceptor protein, recoverin, which has been shown to mediate the recovery of the dark current after photoactivation, and 58% homology to the calcium-binding chick cone protein, visinin. Analysis of the gene indicated a 9-10 kb single-copy gene with at least three exons and two introns. The three exons contained the entire coding sequence, and all of the calcium-binding EF-hand regions were in putative exon 1. The recoverin gene was mapped to human chromosome 17 by hybridization to a panel of human-rodent hybrid DNAs.

Amino Acid Sequence↗
PubMed1992

A deletion in the ornithine aminotransferase gene in gyrate atrophy.

Gyrate atrophy (GA) is an autosomal recessive chorioretinal degenerative disease of the eye caused by an inborn defect of the nuclear encoded mitochondrial enzyme ornithine aminotransferase (OAT). We have described previously a GA patient with a 5.0-kilobase pair truncated EcoRI OAT gene fragment and the absence of OAT mRNA on Northern blot analysis. Cloning and sequencing analysis of the truncated gene fragment revealed a 1,072-base pair (bp) deletion including the entire exon 6, starting in intron 5, 172 bp upstream of exon 6 and ending in intron 6, 772 bp downstream of exon 6. A short direct repeat sequence (AGGAGC), resembling the sequence shown to cause DNA polymerase alpha to pause, and sequences capable of forming hairpin loops were both present at the 5' and 3' break-points of the deletion. Reverse transcription-polymerase chain reaction amplification of the patient's RNA with OAT primers yielded DNA fragments of two different sizes, consistent with a low level expression of OAT mRNA. Direct sequencing of the smaller fragment demonstrated the complete absence of exon 6 sequence in the mRNA predicted from the deletion, causing a reading frame shift which results in a premature termination codon at position 192. The mutation in the other allele has been demonstrated by polymerase chain reaction, denaturing gradient gel electrophoresis, and direct sequencing also to be a premature termination codon in exon 6. The absence of detectable OAT mRNA in this patient is consistent with these premature termination mutations because they have been shown to decrease the level of mRNA, especially if present early in the coding sequence.

Amino Acid Sequence↗
PubMed1992

Purification of serine hydroxymethyltransferase from Bacillus stearothermophilus with ion-exchange high-performance liquid chromatography.

The gene of serine hydroxymethyltransferase (SHMT) of a thermophilic bacterium Bacillus stearothermophilus was expressed in Escherichia coli, and SHMT was successfully purified from the crude extract of E. coli in two steps while maintaining the enzymatic activity. The purification steps involved ammonium sulphate precipitation followed by high-performance liquid chromatographic separation using the anion-exchange column Fractogel EMD DEAE-650(S). In addition to the DEAE column, three other types of anion- and cation-exchange columns were also studied for their ability to separate SHMT, and the performance of the four columns were compared.

Ammonium Sulfate↗