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Biomedical subjects

M Shimada

Publications and source records attributed to M Shimada.

At least 487 records · Page 27Linked to original sources

Regulation of low density lipoprotein receptor activity in Chinese hamster ovary cells transfected with the c-fms gene.

Chinese hamster ovary (CHO) cells were transfected with the human c-fms gene, which encodes the receptor for macrophage colony-stimulating factor, to examine the effects on the low density lipoprotein (LDL) receptor activity. Degradation of [125I]LDL was significantly reduced in the transfected CHO cells as compared to non-transfected cells when incubated in lipoprotein-deficient serum. Quantitative analysis of LDL receptor mRNA using a competitive PCR method demonstrated that LDL receptor suppression occurred at transcription. These findings suggest that expression of the c-fms gene is involved in the regulation of LDL receptors on macrophages.

Animals↗

Cloning, characterization and chromosomal assignment of the human genes homologous to yeast PMS1, a member of mismatch repair genes.

Mutations in genes associated with the DNA mismatch repair system were considered to play important roles in predisposition to cancer, since hMSH2 and hMLH1, human homologues of yeast MSH2 and MLH1 as well as bacterial mutS and mutL genes, were found to be involved in hereditary nonpolyposis colorectal cancer (HNPCC). In addition, yeast PMS1 that is homologous to bacterial mutL and hexB, has also been proven to be related to the DNA mismatch repair system. As the first step to understand whether human homologue of the yeast PMS1 gene is associated with genetic predisposition to cancer, we have isolated and analyzed human counterpart of yeast PMS1 genes. DNA sequencing analyses indicated that human PMS genes constituted a multiple gene family and that some of the family members have been mapped to chromosomal bands 7q11.23 and 7q22 by fluorescent in situ hybridization.

Amino Acid Sequence↗

Postnatal development of [D-Ala2]deltorphin-I-like immunoreactive structures in the rat brain.

[D-Ala2]deltorphin-I, a highly selective ligand for delta opioid receptors, is a heptapeptide originally purified from frog skin. Previous immunohistochemical studies indicate that [D-Ala2]deltorphin-I-like molecule(s) may be present in adult rat brain, including specific neuronal cells and fibers partially overlapping with the mesocortical and nigrostriatal dopaminergic systems. Here, we examined the developmental aspect of such immunoreactive brain structures in early postnatal rats. In newborn to 21-day-old rats, positive staining in the brain occurred mainly in subpopulations of neurons and occasionally in tanycytes. On postnatal day 0, neuronal cell bodies containing [D-Ala2]deltorphin-I-like immunoreactivity were found in various brain regions, including the olfactory tubercle, ventral pallidum, hippocampus, ventral tegmental area, pars compacta of the substantia nigra, supramammillary nucleus, and dorsal raphe nucleus. Immunoreactive nerve fibers were observed in the main and accessory olfactory bulbs, olfactory tubercle, prelimbic area, anterior cingulate cortex, neostriatum, accumbens, lateral septal nucleus, lateral habenular nucleus, and superior colliculus. As pups grew, positive staining of cell bodies decreased gradually in both density and intensity, and those in the olfactory tubercle and ventral pallidum were no longer visible on postnatal day 14. On postnatal day 21, positive cells were found only in the ventral midbrain, including the pars compacta of the substantia nigra, ventral tegmental area, A8 region, and supramammillary nucleus. Positive fibers also decreased in density with age except in the accessory olfactory bulb, olfactory tubercle, prelimbic area, and anterior cingulate cortex.

Amino Acid Sequence↗

Structure of a gene and cDNA of a major constitutive form of testosterone 6 beta-hydroxylase (P450/6 beta A) encoding CYP3A2: comparison of the cDNA with P450PCN2.

P450/6 beta A gene was isolated from a rat genomic library and its encoding protein was characterized by the expression of the corresponding cDNA in COS-1 cells. Between exon regions of P450/6 beta A gene and P450PCN2 cDNA (F. J. Gonzalez, B.-J. Song, and J. P. Hardwick (1986) Mol. Cell. Biol. 6, 2969-2976), 12 nucleotide differences were observed, involving two amino acid changes, His-->Asp [429] and Asp-->Gly [445], respectively. A cDNA (6 beta-A cDNA), whose nucleotide sequence was completely identical with the corresponding exon of P450/6 beta A gene, was isolated from a rat cDNA library. Northern blotting using specific oligonucleotide probes showed that 6 beta-A mRNA, but not P450PCN2 mRNA, was a major form in livers of the male rats. 6 beta-A protein expressed in COS-1 cells (at about 0.1 to 0.3% of total microsomal protein) catalyzed testosterone 6 beta-hydroxylation. The reaction was enhanced by the addition of NADPH-P450 reductase (2.5-fold) and by the simultaneous addition of cytochrome b5 and NADPH-P450 reductase (13.7-fold). Catalytic properties of 6 beta-A for typical CYP3A substrates were consistent with those of purified rat P450(6 beta-1) and P450(6 beta-3), corresponding, respectively, to CYP3A2 or the variant form (K. Nagata, F. J. Gonzalez, Y. Yamazoe, and R. Kato (1990) J. Biochem. 107, 718-725). Apparent Michaelis constants (Km) of 6 beta-A for testosterone 6 beta-hydroxylation and a O-dealkylation ratio of propoxycoumarin to pentoxycoumarin, however, showed higher degrees of similarity to those of purified P450(6 beta-3) than those of P450(6 beta-1).

Amino Acid Sequence↗

Frequent replication errors at microsatellite loci in tumors of patients with multiple primary cancers.

Nearly 10% of cancer patients develop a second primary cancer within 10 years after surgical removal of the first tumor. Hence, detection of a genetic risk for developing multiple primary tumors would be of clinical importance. To investigate whether a genetic defect(s) involving the mismatch repair system constitutes an important risk factor in patients with multiple primary cancers, we examined replication errors (RER) at microsatellite loci in 79 primary cancers which had developed among 38 patients with multiple primary cancers. The RER(+) phenotype was observed at five microsatellite loci on chromosomes 2, 3, 11, or 17 in tumors from 34 (89%) of 38 patients with multiple primary cancers but only in 19 tumors from 174 patients (11%) with a single primary cancer. Our results suggested that: (a) genetic instability may play an important role in development of multiple primary cancers, and (b) testing for RER in a primary cancer may be an appropriate approach to detection of patients at high risk for developing multiple primary cancers.

DNA Repair↗

[Human water-contact study on schistosomiasis--its aim, achievement and prospective].

Parasitic helminths can not choose a strategy for fighting against their hosts but can only compromise with them. They do not kill their hosts because the host is necessary for their survival. Schistosoma haematobium, one of the main causes of tropical parasitic diseases, is a parasitic helminth whose only host is human beings and therefore is considered to evolve fully while adapting to humans. In a human community, the peak intensity and peak prevalence of S. haematobium infection occur in adolescence and suddenly decline thereafter. This is advantageous for the hosts and could be explained as a typical strategy of parasitic helminths. The possible mechanisms of maintaining this host-parasite relationship are the development of acquired protective immunity and the change of human water-contact behavior by age. However, our study in Kenya indicates that the worm burden is regulated mainly by the change of human water-contact behavior. Since human behavior depends on the cultural background of the society, the relation between humans and S. haematobium is an example of the great influence that the human culture has on the host-parasite relationship. For any further investigation of tropical infectious diseases, socio-cultural research is indispensable.

Age Factors↗

Requirements of the secondary structures in the primary transcript for multicopy single-stranded DNA synthesis by reverse transcriptase from bacterial retron-Ec107.

Multicopy single-stranded DNA (msDNA) is produced by bacterial retroelements called retrons. It consists of single-stranded DNA that is linked to an internal G residue of an RNA molecule by a 2',5'-phosphodiester linkage. It has been demonstrated that specific primary sequences, as well as the secondary structures immediately downstream of the G residue, are essential for the cDNA priming reaction (Shimamoto, T., Hsu, M.-Y., Inouye, S., and Inouye, M. (1993) J. Biol. Chem. 268, 2684-2692). We have now examined the requirement of the structures in the region corresponding to DNA for msDNA synthesis. The upper stem region consisting of 71 bases of msDNA-Ec107 was found not to be essential, and this region could be deleted to efficiently produce a truncated msDNA containing only a 36-base single-stranded DNA. Various mutations including base replacements, deletions, and insertions were constructed in the lower stem region. It was found that any mutations resulting in more stable secondary structures caused reduction in msDNA synthesis. The results indicated that reverse transcriptase requires a loose secondary structure in the template RNA near the cDNA priming site for cDNA elongation.

Base Sequence↗

Metabolism of chylomicron remnants in transgenic mice expressing apolipoprotein E in the intestine.

Apolipoprotein E (apoE) has high affinity for the cell surface low density lipoprotein (LDL) receptor. To determine the role of apoE in plasma chylomicron clearance, a transgenic mouse line which overexpresses apoE in the intestine was established. Immunohistochemistry demonstrated that considerable amounts of apoE were localized to mucosal cells of the intestine. In an oral retinyl palmitate challenge test, both the peak height and area under the curve in transgenic mice were less than 25% of those in controls. We speculate that the apoE molecules produced in the intestine of transgenic mice were incorporated onto newly synthesized chylomicron particles before their secretion into the plasma and thereby contributed to rapid plasma clearance of chylomicron remnants. Gene expression of apoE in the intestine would be a promising way to control postprandial hyperlipemia.

Administration, Oral↗

Modulation of coagulation and fibrinolysis in hepatic resection: a randomized prospective control study using antithrombin III concentrates.

A randomized prospective control trial for determining the efficacy of antithrombin III concentrates in hepatic resection was performed using 24 patients with hepatocellular carcinoma. Thirteen patients were given antithrombin III concentrates (1,500 IU) immediately before operation, during hepatectomy and immediately after operation. Coagulant and fibrinolytic profiles were determined by molecular markers such as thrombin-antithrombin III complex and plasmin-alpha 2plasmin inhibitor complex. During hepatic resection, both hypercoagulability and mainly primary hyperfibrinolysis occurred. Regarding the effectiveness of antithrombin III concentrates, in the antithrombin III treatment group, only a significant lower incidence of positive soluble fibrin monomer complex at postoperative days 1 and 5 was found among all the parameters studied. Therefore, no definite evidence of clinical usefulness of the perioperative administration of antithrombin III concentrates in hepatic resection was proved.

Aged↗

Specificity of priming reaction of HIV-1 reverse transcriptase, 2'-OH or 3'-OH.

It has not been unambiguously demonstrated whether the priming reaction of human immunodeficiency virus, type 1 (HIV-1) cDNA synthesis initiates with either the 2'-OH or 3'-OH group of the 3'-terminal adenosine residue of tRNA(Lys-3). In this report, we synthesized tRNA(Lys-3) of which the 3'-terminal adenosine residue lacks either a 2'-OH or 3'-OH. These tRNA molecules were used for the HIV-1 cDNA-priming reaction in a cell-free system consisting of a 141-base RNA template and purified HIV-1 reverse transcriptase. It was found that under the conditions used, the tRNA containing the 2'-deoxyadenosine was able to initiate the cDNA synthesis, while the tRNA with the 3'-deoxyadenosine was not. The results show that retroviral reverse transcriptase specifically primes cDNA synthesis from the 3'-OH group. This is in contrast to bacterial reverse transcriptase, which initiates cDNA synthesis from the 2'-OH group of an internal guanosine residue of a template RNA.

Base Sequence↗

Multiple hepatic hemangiomas with significant arterioportal venous shunting.

A patient with multiple hepatic hemangiomas and significant arterioportal shunting who was successfully treated by a left-hepatic lobectomy is presented herein. In hemangiomas with significant arterioportal venous shunting, it is essential to differentiate between hepatocellular carcinoma and hypervascular metastatic tumors because few typical findings of hemangioma can be recognized. Moreover, an increased hepatic arterial flow can increase the risk of spontaneous rupture as well as portal hypertension due to the increased inflow to the portal vein. Therefore, a definitive diagnosis should be made by liver biopsy when imaging alone is not sufficient to rule out malignancy. Furthermore, hepatic resection for hemangiomas with significant arterioportal venous shunting may be indicated due to the higher risk of rupture and the possibility of progressive portal hypertension.

Angiography↗

Liver resection for hepatocellular carcinoma in the elderly.

OBJECTIVE: To estimate the effectiveness of hepatic resection on hepatocellular carcinoma (HCC) in the elderly. DESIGN: Comparison with younger patients. SETTING: A municipal hospital and a large university hospital in Japan. PATIENTS: The study included 39 patients (age > or = 70 years [the elderly group]) and 229 patients (age < 70 years [the younger group]) who underwent hepatic resection from April 1985 to March 1993. The preoperative clinical features (Child's classification, association of cirrhosis and liver functions) were comparable between two groups. The positive rate for hepatitis C virus antibody was higher in the elderly group (88% vs 59%; P = .016). MAIN OUTCOME MEASURES: Morbidity and survival following operation and the pathological features of HCC. RESULTS: The incidence of postoperative hepatic failure was higher in the elderly group (10% vs 2%; P = .018). However, the incidence of operative death in the elderly group (5% vs 1%) as well as the incidence of other postoperative complications and rates of long-term survival (75.9% vs 51.6% at 5 years) and disease-free survival (30.4% vs 31.0% at 5 years) were similar to those in the younger group. The pathological features of HCC were identical between the two groups. CONCLUSION: The outcome of surgical treatment of HCC in the elderly group was satisfactory when compared with that in the younger group.

Age Factors↗

Detection of hepatitis C virus RNA in the ultrasonic dissector irrigating solution used in liver surgery.

Hepatitis C virus (HCV) RNA was detected in the irrigating solution aspirated by the ultrasonic dissector system used in liver surgery with a reverse transcription polymerase chain reaction technique and was then compared with HCV RNA in the serum to clarify the risk of viral transmission to hospital personnel. The positivity of HCV RNA in the aspirated irrigating solution was approximately equal in all patients whose serum was positive for HCV RNA. However, viral RNA was not detected in the aspirated irrigating solution of any patient who was seronegative for HCV RNA. These results indicate that it is necessary to be cautious regarding the transmission of HCV during liver surgery when using the ultrasonic dissector in HCV RNA seropositive patients, because the irrigating solution aspirated by this device appears to be highly infectious.

Aged↗

Expression of desmoglein I in squamous cell carcinoma of the esophagus.

Desmoglein I (DGI) is major component of the desmosomal membrane core that plays an important role in epithelial cell adhesion. The aim of this study was to explore the correlation between the expression of DGI and the clinicopathological findings of esophageal cancer. DGI expression was immunohistochemically examined using an anti-DGI monoclonal antibody in 139 patients with squamous cell carcinoma of the esophagus. Normal squamous epithelial cells strongly expressed DGI at their cell-cell boundaries. According to the intensity and pattern of DGI expression, the cancerous tissues were divided into three groups: DGI (++), DGI (+), and DGI (-). Of the 139 tumors, 35 (25%) were DGI (++), 65 (47%) were DGI (+), and 39 (28%) were DGI (-). A good inverse correlation between DGI expression and tumor invasion, lymph node metastasis, lymphatic invasion, and vessel invasion was observed. These results indicate that DGI expression may be a significant factor for invasion, metastasis, and prognosis of human esophageal cancer.

Adult↗

In vivo activity of bleomycin incorporated with biodegradable poly-d,l-lactic acid and implanted in the mediastinum of dogs.

The possible usefulness of bleomycin incorporated with biodegradable poly-d, l-lactic acid (BLM-PLA) for targeting chemotherapy for esophageal cancer was studied in vivo. Local levels of BLM after administration were compared with those after injection of BLM-SOL, an aqueous solution of BLM. BLM-PLA or BLM-SOL was administered into the upper mediastinum under a right thoracotomy in 36 mongrel dogs. On days 10, 20, and 30 after administration, connective tissues, lymph nodes, lung, liver, kidney, and spleen were removed, and BLM activity was measured. High activity of BLM was detected for 30 days after BLM-PLA administration in both the connective tissues and the lymph nodes, compared with BLM-SOL administration. BLM activity was low in the other organs after BLM-PLA administration. BLM in the blood was significantly lower after administration of BLM-PLA than BLM-SOL. The results indicate that BLM-PLA may become a useful tool in targeting chemotherapy for esophageal cancer.

Animals↗

Cloning and expression in Escherichia coli of the gene encoding the Proteus vulgaris chondroitin ABC lyase.

The structural gene encoding chondroitin ABC lyase from Proteus vulgaris was cloned and sequenced. This gene consists of a single open reading frame of 3,063 bp, including a sequence (72 bp) for a possible secretory protein leader peptide, preceded by a Shine-Dalgarno ribosomal binding site. Promoter-like and rho-independent terminator sequences were detected upstream and downstream of the open reading frame, respectively. The G+C content of the coding region was 38.6%. The transcription startpoint was located 41-bp upstream of the initiation codon (ATG). Chondroitin ABC lyase is composed of 997 amino acids, and has a relative molecular mass of 112,635. When the 5.2-kb fragment containing the 1.2-kb upstream from the gene was inserted into pSTV29, and cloned in Escherichia coli, chondroitin ABC lyase was induced in the medium containing chondroitin-6-sulfate as the carbon source. On the other hand, when a 4.2-kb fragment containing only 0.2 kb upstream was inserted into pSTV29(pCHS delta 6), and pCHS delta 6 was introduced into E. coli, the enzyme was constitutively produced, even in medium containing glucose as the carbon source. By immunoblot analysis, the polypeptide synthesized by E. coli cells carrying pCHS delta 6 appeared to be the same as that of the purified chondroitin ABC lyase from P. vulgaris.

Amino Acid Sequence↗