Molecular mechanism of adaptive response to alkylating agents.
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Alkylating Agents↗
Biomedical subjects
M Sekiguchi
Publications and source records attributed to M Sekiguchi.
Changes in the peripheral vasculature of various organs in patients with sarcoidosis--possible role of microangiopathy.
Vascular involvement in sarcoidosis is briefly reviewed with emphasis on the outcome of a 10-year project-study by the Sarcoidosis Research Committee of the Japanese Ministry of Health and Welfare. Examples of vascular disorder associated with sarcoidosis are presented, including basal lamina layering of the capillaries in the skeletal muscle, cardiac muscle, and lung, glomerulopathy in the kidney, vascular changes in the ocular fundus and bronchi, and impaired peripheral circulation that could be detected by thermography. According to our tentative definition, all of these disorders should be collectively called microangiopathy. The possible role of microangiopathy in the pathogenetic mechanism of sarcoidosis is also discussed. Although microangiopathy in sarcoidosis is a comprehensive term, it should be included, in addition to systemic granulomatous disease, as part of the clinicopathological entity of sarcoidosis.
Bronchi↗
Structure and function of dnaQ and mutD mutators of Escherichia coli.
The nucleotide sequences of the recessive dnaQ49 and the dominant mutD5 mutator were determined. The dnaQ49 mutator has a single base substitution in the dnaQ gene, thus causing one amino acid change, 96Val (GTG)----Gly (GGG), in the DnaQ protein (epsilon subunit of DNA polymerase III holoenzyme). The mutD5 mutator possesses two base substitutions in the same gene, resulting in two amino acid changes, 73Leu (TTG)----Trp (TGG) and 164Ala (GCA)----Val (GTA), which were designated the mutD52 and mutD51 mutations, respectively. Construction of chimaeric genes carrying one or two of these mutations revealed: either mutD51 or mutD52 alone causes the dominant mutator phenotype when present in a multi-copy plasmid; mutator phenotype when present in a low-copy plasmid; the dominant mutD51 mutator activity is suppressed by the dnaQ49 mutation when both mutations are present in the same gene. Based on these findings, we devised a model for the action of these mutators.
Amino Acid Sequence↗
Transfer of the E. coli O6-methylguanine methyltransferase gene into repair-deficient human cells and restoration of cellular resistance to N-methyl-N'-nitro-N-nitrosoguanidine.
We have constructed a plasmid on which the E. coli O6-methylguanine-DNA methyltransferase (MT) gene (ada gene) was linked with an SV40 promoter sequence and a poly(A) site. After transferring this plasmid into Mer- HeLa MR cells by DNA transfection, effective expression of E. coli MT was observed. Isolated stable transformant clones showed higher resistance to N-methyl-N'-nitro-N-nitrosoguanidine in colony formation and sister-chromatid exchange induction than HeLa MR cells.
Cell Survival↗
Transforming gene from human stomach cancers and a noncancerous portion of stomach mucosa.
DNAs from 21 human stomach cancers, 16 metastatic stomach cancers to lymph nodes, and 21 apparently noncancerous specimens of stomach mucosae from a total of 26 patients with stomach cancer were tested for their ability to induce neoplastic transformation of NIH 3T3 cells on transfection by the calcium phosphate precipitation technique. Three samples of DNA were shown to have transforming activity; one was from a primary stomach cancer of one patient, the second was from a noncancerous portion of stomach mucosa of the same patient, and the third was from a lymph node metastasis of stomach cancer from another patient. These transformants were tumorigenic in nude mice, and DNAs from the cells could induce secondary transformants. A portion of the transforming gene from the stomach cancer of one patient, which contained the sequences expressed in the NIH 3T3 transformants, was cloned. The transforming gene did not have any homology with the transforming sequences reported previously. We have applied the term hst to this novel human transforming gene. The transforming gene, hst, was found to be present in all the primary and secondary transformants induced by the other two samples of DNA.
Adenocarcinoma↗
Regulatory mechanisms for induction of synthesis of repair enzymes in response to alkylating agents: ada protein acts as a transcriptional regulator.
Expression of the ada and alkA genes, both of which are involved in the adaptive response of Escherichia coli to alkylating agents, is positively controlled by Ada protein, the product of the ada gene. Large amounts of ada- and alkA-specific RNA were formed in cells treated with a methylating agent, whereas little such RNA was produced in untreated cells. The in vivo transcription-initiation sites for the two genes were determined by primer-extension cDNA synthesis. In an in vitro reconstituted system, both ada and alkA transcripts were formed in an Ada protein-dependent manner. However, responses of the two transcription reactions to methylating agents differed; ada transcription was stimulated by methylnitrosourea, while alkA transcription was suppressed. We prepared a methylated form of Ada protein by an in vitro reaction and compared the activity with that of the normal, unmethylated form. The methylated form was more effective in promoting ada transcription than was the unmethylated form, but the effects of both forms were much the same with regard to alkA transcription. Based on these findings, we propose a model for the molecular mechanism of adaptive response.
Alkylating Agents↗
Structure of the activated c-raf-1 gene from human stomach cancer.
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Animals↗
Molecular cloning of a human gene that regulates chromosome condensation and is essential for cell proliferation.
The tsBN2 cell line, a temperature-sensitive (ts) mutant of baby hamster kidney cell line BHK21/13, seems to possess a mutation in the gene that controls initiation of chromosome condensation. At the nonpermissive temperature (39.5 degrees C), the chromatin of tsBN2 cells is prematurely condensed, and the cells die. Using tsBN2 cells as a recipient of DNA-mediated gene transfer, we investigated a human gene that is responsible for regulation of chromosome condensation and cell proliferation. We found that the human gene complementing the tsBN2 mutation resides in the area of the 40- to 50-kilobase HindIII fragment, derived from HeLa cells. Based on this finding, we initiated cloning of a human gene complementing the tsBN2 mutation. From lambda and cosmid libraries carrying partial digests of DNA from the secondary transformants, the 41.8-kilobase HindIII fragment containing the human DNA was isolated. The cloned human DNA was conserved in ts+ transformants through primary and secondary transfections. Two cosmid clones convert the ts- phenotype of tsBN2 cells to ts+ with more than 100 times a higher efficiency, compared with cases of transfection with total human DNA. Thus, the cloned DNA fragments contain an active human gene that complements the tsBN2 mutation.
Cell Cycle↗
Age-associated myocardial changes in various heart diseases. A clinicopathologic analysis in biopsied and autopsied myocardium.
Age-associated changes in histopathologic and ultrastructural aspects of cardiac myocytes were systematically compared with clinical problems. The study material consisted of 1,515 endomyocardial biopsies; 150 normal and 50 diseased cardiac myocytes from pediatric autopsy specimens; 34 intraoperative endomyocardial biopsy specimens from the left ventricle and 28 surgical biopsy specimens from the right or left atrium. The following results were obtained: The myocytes developed to adult size by the age of 15 years. Thereafter, the size did not change up to the age of 59. Short-term hemodynamic overloading to the ventricle caused reactive hyperfunction and hypertrophy of myocytes. Stable hypertrophy resulted in long-term overloading. In cardiomyopathy, compensated or stable hypertrophy occurred, but progression to decompensated or gradual exhaustion and progressive cardiosclerosis (Meerson) took place. Progress of endocardial thickening was often observed during the course of the disease. In the right and left atrial myocardium, extremely advanced pathology was observed and changes were related to the duration of the disease rather than to the severity of the hemodynamics.
Aging↗
Analysis of histopathologic findings in cases with dilated cardiomyopathy with special reference to formulating diagnostic criteria on the possibility of postmyocarditic change.
From our study employing serial endomyocardial biopsy in patients with acute viral or idiopathic myocarditis, we were able to construct histopathologic criteria for acute, subacute and convalescent myocarditis. We realize that it is difficult for the inexperienced observer to make an appropriate diagnosis of myocarditis or postmyocarditic changes in patients with dilated cardiomyopathy (DCM). In order to overcome this problem, each finding was graded and the scores obtained were analyzed statistically and compared with those from hypertrophic cardiomyopathy (HCM) and chronic right ventricular overloading (CRVO). The scores were obtained by summing the gradings for each of the following findings: increase of fibrocytes, increase of fibroblasts in the interstitium, hypertrophy of myocytes, fragmentation of muscle bundles, interstitial fibrosis, disarrangement of muscle bundles, abnormal branching, variation in size, increased glycogen deposition in the sarcoplasm, scarcity of myofibrils, and nuclear degeneration of myocytes and endocardial thickening. Since the increase in number of fibrocytes was considered important, its value was doubled. Scores in each group were as follows: convalescent myocarditis: 17.1 +/- 4.7 (n = 10), DCM: 13.2 +/- 3.3 (n = 47), HCM: 9.7 +/- 2.4 (n = 20), CRVO: 7.0 +/- 3.6 (n = 21). It was found that the scores for cases with myocarditis in the convalescent stage and in DCM were higher than those found for cases with either HCM and CRVO (p less than 0.05). In summary, the high score for postmyocarditis in DCM could suggest that prior myocarditis is an important causative factor of this disease.
Biopsy↗
Apolipoprotein E phenotypes and plasma lipids in young and middle-aged subjects.
The relationship between apolipoprotein (apo) E phenotypes and the levels of plasma lipid, lipoprotein and apo E in young (mean, 21 years of age) and middle-aged (mean, 49 years of age) subjects was investigated. Apo E phenotypes were determined by a rapid flat gel isoelectric focusing method that we had developed previously. Young subjects with apo E3/2 and E4/3 had significantly higher levels of plasma triglyceride (TG), very low density lipoprotein (VLDL)-TG and VLDL-cholesterol than those with apo E3/3. Middle-aged subjects with apo E3/2 (54.5%) and E4/3 (39.1%) had higher frequency of hyperlipoproteinemia (mainly type IV) than those with apo E3/3 (25.8%). Furthermore, the middle-aged subjects with apo E3/2 had significantly higher levels of plasma TG, VLDL-TG and apo E, and significantly lower levels of plasma high density lipoprotein-cholesterol than those with apo E3/3. These results indicate that apo E phenotype E3/2 and E4/3 are associated with lipid abnormalities even in young subjects, which may be caused by impaired functions of apo E2 and E4.
Adolescent↗
[A case of sarcoid polyneuropathy with granuloma in the peripheral nerve].
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Female↗
Apolipoprotein E polymorphism and hyperlipemia in type II diabetics.
The relationship between apolipoprotein E (apoE) polymorphism and plasma lipids and hyperlipemia was investigated in 105 male type II diabetics and 111 male nondiabetics. ApoE phenotypes were determined by a one-dimensional rapid flat gel isoelectric focusing method as described previously. The apoE phenotype frequency in diabetics was similar to that in nondiabetics. The frequency of hyperlipemia was higher in diabetics (56.2%) than in nondiabetics (32.4%). It was highest in the apoE3/2 group of diabetics and nondiabetics, followed by the apoE4/3 and apoE3/3 groups in the order described, indicating that the susceptibility to hyperlipemia differs among the apoE phenotype groups. ApoE3/2 diabetics had significantly higher levels of apoE and very-low-density lipoprotein (VLDL) cholesterol (chol)/VLDL triglyceride (TG) ratios than apoE3/3 diabetics. The effects of diabetes mellitus on plasma lipid levels differed among the various apoE phenotype groups: i.e., plasma total chol and low-density lipoprotein (LDL) chol increased only in apoE3/2 and apoE4/3 diabetics and plasma high-density lipoprotein chol decreased only in apoE3/3 diabetics, as compared with the corresponding apoE phenotype groups of nondiabetics, whereas plasma TG, VLDL TG, and VLDL chol increased in the three apoE phenotype diabetics. Furthermore, an increase of apoEII:apoEIII ratio was observed in apoE3/3 diabetics, particularly in those with hypertriglyceridemia. This study has also shown that the increased apoEII:apoEIII ratio is due to increased sialation of apoE based on the study of sialidase digestion of apo VLDL.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
The correlation between the diameter of biopsied left and right ventricular myocardial cells and hemodynamic parameters in essential hypertension and mitral valve disease.
For the purpose of studying the correlation between the diameter of myocardial cells and hemodynamic parameters in human beings, the left ventricular endomyocardial biopsy was performed in 29 cases. Eleven cases were normotensive patients. The remaining 18 subjects had a history of hypertension for more than 5 years. The mean diameter of the left ventricular myocardial cells was correlated with the systolic aortic pressure (r = 0.51, p less than 0.01) and the systemic vascular resistance index (r = 0.66, p less than 0.01). The same study was done on the right ventricle of 7 controls and 11 patients with mitral valve disease in which chronic right ventricular pressure overload was present. The mean diameter of myocardial cells biopsied from the right ventricle was correlated with the systolic pulmonary arterial pressure (r = 0.61, p less than 0.01) and the pulmonary vascular resistance index (r = 0.72, p less than 0.01). These findings indicate that the diameter of myocardial cells in both the left and right ventricles was closely related with its afterload.
Adult↗
Expression of transferrin receptor on human carcinomas--an immunohistological study.
Thirty specimens taken from 25 adenocarcinomas, 1 squamous cell carcinoma, 2 anaplastic carcinomas and 2 malignant lymphomas were studied for the presence of transferrin receptor (TR). Immunoperoxidase technique was used and OKT9, an anti-transferrin receptor monoclonal antibody, was introduced. The tissue localization of carcino-embryonic antigen (CEA) and epithelial membrane antigen (EMA) were also studied. Of these, 5 cases were strongly stained for TR, 17 moderately and 6 weakly stained. TR was demonstrated on the basal site while luminal preference was evident with CEA and EMA. This polarity was observed in the well- to moderately-differentiated adenocarcinomas and in the well-differentiated squamous cell carcinoma but not in the poorly-differentiated and anaplastic variants. Putatively normal epithelium registered very weak positivity though the polarity was still maintained.
Adenocarcinoma↗
Structure of the activated c-raf-1 gene from human stomach cancer.
We previously isolated a novel human transforming gene from a primary stomach cancer and identified it as an activated version of the c-raf-1 gene which is the human homologue of v-raf, a viral oncogene encoding a serine/threonine-specific protein kinase. Analyses of cDNA and genomic clones of this gene revealed that it was generated by substitution of 5'-sequence (exons 1-5) of the normal c-raf-1 gene with an unrelated human sequence. We identified the region in the genomic clone where the rearrangement had occurred. The rearranged EcoRI fragment was detected in all the primary transformants obtained from two independent transfections, suggesting that the recombination had occurred in the primary cancer. By sequence analysis of cDNA, the putative product of the transforming gene was inferred to have a hydrophobic stretch ahead of the ser/thr-protein kinase domain of the c-raf-1 gene product. We introduced one of the cDNA which contains the 1.6-kb open reading frame into the pUC9 vector. An autophosphorylating, 58 kd protein was induced in Escherichia coli cells bearing the plasmid upon induction. Since ser/thr-protein kinase activity of the normal c-raf protein has not been evidenced, these results suggest that the truncation/replacement of the amino-terminal domain of the c-raf-1 protein leads to constitutive activation of the protein kinase probably residing on the downstream domain.
DNA Restriction Enzymes↗
[Changes in nonspecific suppressor factors in the serum of gastric cancer patients after surgery and immunochemotherapy].
After curative surgery for gastric cancers judged macroscopically to be at stage 2 or 3, patients were divided into 4 groups by randomization. As the basic treatment, patients were given one-shot Mitomycin and Tegafur as maintenance therapy for 8 months (group A). PSK (group B), OK-432 (group C) or both PSK and OK-432 (group D) were added to the treatment of group A for 8 months. Sera were obtained from these groups of patients at 4 weeks and 3, 6, 9 and 12 months after surgery. In all of these groups, values of IAP increased slightly at 4 weeks but decreased at 3 months and were maintained at such a level by 12 months. On the other hand, suppressive effects of such sera on the blastogenesis of murine spleen cells in response to PHA varied among these group. In groups A and C, the suppressive effect of sera increased after surgery and was detected continuously by 12 months. In groups B and D, in contrast, the suppressive effect disappeared from 3 to 12 months. The rise and fall of such a suppressive effect of sera may reflect the mode of action of PSK.
Female↗
Detection of amplified DNA sequences in gastric cancers by a DNA renaturation method in gel.
A DNA renaturation method in gel was used to detect amplified DNA fragments in eight gastric cancer cell lines, KATO-III, OKAJIMA, SCH, MKN1, MKN7, MKN28, MKN45 and MKN74 cells, and tissues of three metastases of gastric cancers to lymph nodes. There were amplified DNA sequences in three gastric cancer cell lines. Judging from the intensities of the bands, HindIII-digested DNA fragments were amplified several hundred times in the KATO-III and MKN7 cell lines. DNA from OKAJIMA cell line contained multiple bands with less intensity. KATO-III cells were found to contain a homogeneously staining region in chromosome 11.
Base Sequence↗