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Biomedical subjects

M Sekiguchi

Publications and source records attributed to M Sekiguchi.

At least 469 records · Page 26Linked to original sources
PubMed1987

Development of myocardial contractile system in the fetal rabbit.

Developmental changes in the myocardial contractile system were evaluated in the fetus at 18, 21, and 28 days of gestation (full term 31 days) and in 3- to 5-day-old newborn rabbits. Mechanical function was studied using the isolated arterially perfused heart. Perfusion with ryanodine (10(-5) M), an inhibitor of Ca release from the sarcoplasmic reticulum, decreased contractile force and increased the time to peak tension in the 28-day fetus and newborn but these changes were minimal in the 18- and 21-day fetus. Postextrasystolic potentiation, which is thought to be caused by Ca release from the sarcoplasmic reticulum, was observed in the 28-day fetus and the newborn, but was not significant in the 18- and 21-day fetus. An ultrastructural study showed poorly developed sarcoplasmic reticulum and myofibrils in the 18- and 21-day fetus. Although the maximum developed tension observed at high extracellular calcium increased with development, the relative value of developed tension at various extracellular calcium was similar in the three fetal groups and only in the newborn the extracellular calcium-developed tension curve shifted to the right. Myofibrillar yield increased with development but sensitivity of myofibrillar ATPase activity to Ca was similar in the fetus and newborn. These data suggest that 1) the sarcoplasmic reticulum does not function significantly in the 18- and 21-day fetus, 2) although sarcoplasmic reticulum starts to function at late gestation, it does not cause significant changes in intracellular calcium in the fetal period, 3) myocardial contractility remains similar in the fetus from the 18th to 28th day of gestation and major changes in contractility occur after birth.

Animals↗
PubMed1987

Mechanism of luminal enlargement in PTCA and restenosis: a histopathological study of necropsied coronary arteries collected from various centers in Japan.

Necropsy studies of coronary arteries were made in 14 patients who died after percutaneous transluminal coronary angioplasty (PTCA). Eight patients died shortly after PTCA, while the other six patients died some considerable time later. A total of 9,920 serial step sections of necropsied coronary arteries at the site of PTCA were prepared and examined histopathologically by light microscope to determine the mechanism of luminal enlargement in PTCA, as well as the occurrence of restenosis. Of the eight patients who died shortly after PTCA, two had disruption of the intima and the media in the arterial wall located opposite the site that had atheroma, in spite of the fact that the former wall is more normal than the latter. Dissection of the media was camed out in four patients and intimal desquamation performed in six. All the patients revealed fresh thrombus formation. Of the six patients who survived for a long time after PTCA was performed, two had disruption of the intima and the media located opposite the site with atheroma. In one, the media was dissected and in another, intimal desquamation was camed out. In one patient, release of atheroma into the lumen was suspected. Proliferation of intimal cells was revealed in three patients indicating that restenosis had occurred. No compression of the atheroma was observed in any of the 14 patients. The above findings led to the conclusion that the mechanisms of luminal enlargement in PTCA are: 1) intimal and medial disruption in the arterial wall located opposite the atheroma; 2) medial dissection; 3) intimal desquamation; 4) release of atheroma into the lumen; and 5) any combination of 1) -4).

Adult↗
PubMed1987

Endomyocardial biopsy approach to patients with ventricular tachycardia with special reference to arrhythmogenic right ventricular dysplasia.

Right ventricular endomyocardial biopsies were performed in patients with repetitive ventricular tachycardia (VT; 8 patients) or ventricular premature beats (1 patient) which showed left bundle branch block morphology in electrocardiograms. These 9 male patients ranging in age from 21-55 years (mean 37.7 years) revealed enlargement and/or asynergy of the right ventricle in the ventriculogram. Randomly selected biopsied patients with dilated cardiomyopathy (DCM; 18 patients) and chronic right ventricular overloading (14 patients) who did not show the above-described arrhythmias served as controls. A histopathological analysis revealed advanced myocardial interstitial fibrosis associated with an increase in fatty tissue in 8 of the 9 patients (89%). Moreover, advanced hypertrophy of myocytes (grade 2 or more of our criteria), disarrangement of muscle bundles and endocardial thickening were prominent with incidences of 75%, 75% and 78%, respectively. Incidence of all findings was more pronounced in the ARVD group. Suggestiveness of post-myocarditic change in the biopsied specimen was high in 1 patient, showing a lower incidence (12%) than the DCM group (17%). From these results, we can conclude that different etiological factors may be the bases of these pathological changes. We believe that the presence of a large amount of fatty tissue within the myocardial tissue is an important element in the etiology of ventricular arrhythmias as it has also been recognized in patients with non-ARVD idiopathic ventricular tachycardia in our biopsy series.

Adult↗
PubMed1987

Prognosis of dilated cardiomyopathy: from a retrospective to a prospective study employing multivariate analysis.

To determine the prognostic factors of dilated cardiomyopathy (DCM), a retrospective long-term investigation of 111 patients seen between 1967 and 1983 was carried out. Fifty-four deaths were divided into 3 subgroups: (1): sudden death (n = 6); (2): sudden death on the basis of heart failure (n = 17); (3): refractory heart failure death (n = 31). Multivariate analysis was employed to ascertain the prognostic score, which was constructed from the grading of the New York Heart Association functional classification, the cardiothoracic ratio, electrocardiographic findings and cardiac function. Individual variables were indicated on the first (I) and second (II) principal component axes. The mean center points for the death modes were as follows: (1): I = -0.4, II = +0.8, (2): I = +0.7, II = +1.1, (3): I = +1.4, II = -0.8. Surviving cases (n = 57) showed I = -0.6, II = +0.1. Forty-one cases examined during 1984-1985 were analyzed to evaluate the prognostic efficacy of this score. Fourteen of 17 cases (82%) located in the refractory heart failure death group died within one year after determination of the prognosis, showing thereby that the prognostic determination by multivariate analysis is effective.

Adult↗
PubMed1987

Increased frequency of apolipoprotein epsilon 4 allele in type II diabetes with hypercholesterolemia.

The apolipoprotein E (apoE) phenotype and allele frequencies were examined in type II (non-insulin-dependent) diabetic patients with normolipidemia (n = 134) and hypercholesterolemia (type IIa hyperlipoproteinemia, n = 35; type IIb hyperlipoproteinemia, n = 42). The frequencies of apoE4-present phenotypes (apoE4/3, apoE4/4, and apoE4/2) were highest in the type IIa group (51.4%), followed by the type IIb group (38.1%) and the normolipidemic group (16.4%), respectively, whereas the frequency of the most common phenotype, apoE3/3, was lowest in the type IIa group (48.6%), followed by the type IIb group (61.9%) and the normolipidemic group (79.9%), respectively. There were significant differences in the apoE phenotype frequencies between the normolipidemic group and the type IIa and IIb groups. The frequency of the epsilon 4 allele was significantly higher in the type IIa (28.6%) and IIb (20.2%) groups than in the normolipidemic group (8.9%), whereas the frequency of the epsilon 3 allele was significantly lower in the type IIa (71.4%) and IIb (78.6%) groups than in the normolipidemic group (89.2%). The frequency of the epsilon 2 allele tended to be lower in diabetic patients with hypercholesterolemia. In addition, these frequencies were also examined in nondiabetic subjects (n = 59). The frequency of the epsilon 4 allele tended to be higher in hypercholesterolemic diabetic subjects (24.1%) than in hypercholesterolemic nondiabetic subjects (15.3%). These data suggest that diabetic patients with the epsilon 4 allele may be more susceptible to hypercholesterolemia than diabetic patients without the epsilon 4 allele and possibly nondiabetic subjects with the epsilon 4 allele, although the underlying mechanism is unknown.

Adult↗
PubMed1987

Expression and function of class II antigens on gastric carcinoma cells and gastric epithelia: differential expression of DR, DQ, and DP antigens.

The expression of human histocompatibility leukocyte antigen class II antigens on gastric epithelia and gastric carcinoma (GaCa) was studied with the use of murine monoclonal antibodies to DR, DQ, and DP antigens. DR and DP antigens but not DQ antigens were demonstrated in fundic glands of normal gastric epithelia, and DP+ cells were located in part of the DR+ epithelia. Of 15 GaCas examined, 11 expressed DR antigen, and the degree of the expression varied considerably among the specimens. DP antigen was found in 3 of the 11 DR+ carcinomas, and the DQ antigen was found in one of the 3 DR+ DP+ specimens. Thus the expression of class II antigens in normal gastric epithelia and GaCas appears to be in the order of DR, DP, and DQ. Studies on 3 GaCa cell lines (Kato III, MKN28, and MKN45) demonstrated that 1 line (Kato III) expressed DR antigen only, and the remaining lines were negative. Interferon (IFN)-gamma treatment enhanced the expression of DR antigen on Kato III cells and induced expression of DQ and DP antigens. The IFN-gamma treatment also induced expression of DR antigen but not DQ or DP antigens in 1 of the 2 negative cell lines. The induction of the class II antigens by IFN-gamma was shown to be dose dependent. However, maximal induction of DQ and DP antigens on the Kato III cells and DR antigens on MKN45 cells required 10 times more IFN-gamma than that needed for the maximal expression of DR antigen on Kato III. Northern blot analyses of cytoplasmic RNA from these cells were in agreement with and affirmed the above-described expression of the class II antigens on the cell lines. The DR antigen on the Kato III cells was capable of stimulating allogeneic lymphocytes in MLR, and its stimulatory activity was significantly enhanced by IFN-gamma. These results demonstrated a differential expression of class II antigens in the "DR, DP, and DQ order" in normal gastric epithelia, GaCa cells, and GaCa cell lines, suggesting different mechanisms acting discordantly on the expression of each of these antigens and that the DR antigen on the GaCa cell lines possesses MLR-stimulatory ability.

Animals↗
PubMed1987

[A case of metastasis of renal cell carcinoma to the abdominal wall 13 years after nephrectomy].

A 68-year-old man was admitted to our hospital complaining of a tumor of the left abdominal wall. Thirteen years previously, had undergone a nephrectomy of a right renal cell carcinoma with T2, N0, M0, manifestations stage I. Prior to his second operation, a parenchymal tumor was strongly suspected. The tumor, however, was finally diagnosed pathologically as being a metastatic renal cell carcinoma. Postoperatively, the patient has been well for 21 months without any evidence of recurrence at the time of this report. Long-term follow-up is thought to be essential for cases of renal cell carcinoma with a slow-growing type of metastasis.

Abdominal Muscles↗
PubMed1987

Varying methods of sterilisation, and their effects on the structure and permeability of dialysis membranes.

This study elucidates changes in membrane structure and permeability due to the methods of sterilisation and the conditions under which they are carried out. Tubular dialysis membranes of regenerated cellulose having various values for porosity were sterilised by ethylene oxide gas, autoclave or gamma irradiation under varying conditions. Non-sterilised membranes were included as controls. The solute permeability of the membranes was determined using 14C-urea. The membranes tested showed no difference in clearance of urea or creatinine. Gamma-ray sterilisation under dry conditions greatly reduced the vitamin B12 clearance and hydraulic permeability of membranes with a water content of below 60%. Hydraulic permeability increased with gamma irradiation for membranes sterilised under wet conditions. A reduction in vitamin B12 clearance for membranes with a water content of above 60% resulted after autoclave sterilisation. Pore model calculation reveals that membrane shrinkage resulted from sterilisation both by gamma-rays under dry conditions, and by autoclave. Thus, the structure of dialysis membranes varies with the method of sterilisation and the conditions under which the sterilisation is carried out.

Cellulose↗
PubMed1987

[Activated c-raf-1 gene from human stomach cancer].

We previously isolated a novel human transforming sequence from a primary stomach cancer and identified the gene 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. Of 57 kbp of the human sequence isolated, a region of 40 kbp was found to be the minimum functional unit for the transforming activity, because a cosmid clone harboring this region was capable of inducing foci upon transfection. The size of the transcript of the transforming c-raf-1 gene was estimated to be about 2.8kb. Analyses of cDNA clones of this gene revealed that the gene was generated by substitution of the 5'-sequence (exons 1-5) of the normal c-raf-1 gene with an unrelated human sequence. We identified a 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. The substituted cDNA sequence is composed of an open reading frame, which joins to exon 6 of the c-raf-1 gene in an in-phase manner. The substituted open reading frame encodes an extremely hydrophobic polypeptide. Thus, the putative product of the transforming gene seems to have a hydrophobic stretch ahead of the ser/thr-protein kinase domain of the c-raf-1 gene product. These results suggest that the truncation or replacement of the amino-terminal domain of the c-raf-1 protein leads to constitutive activation of the protein kinase residing in the downstream domain.

Cloning, Molecular↗
PubMed1987

Natural history of atrial fibrillation.

The clinical significance of atrial fibrillation was analyzed in cases with chronic or acute heart disease and its significance at the acute and chronic stages of the disease was investigated in various disease groups. The types of disease, number of patients, and incidence of atrial fibrillation were: atrial septal defect (92, 14.1%), mitral valve disease (128, 79.7%), nonrheumatic valvular disease (32, 56.2%), aortic regurgitation (71, 2.8%), aortic stenosis (10, 10.0%), hypertrophic cardiomyopathy (181, 11.6%), dilated cardiomyopathy (111, 37.8%), acute myocardial infarction (823, 9.0%), healthy subjects (31,886, 0.3%). A histopathological and electron-microscopic evaluation of the atrial heart muscle revealed that the advancement of the morphological changes was closely related to the occurrence of atrial fibrillation. Decrease in size of F waves in the electrocardiogram correlated well with the extent of right and left atrial fibrosis. Also, it was noteworthy that the atrial fibrillation in cases with dissecting aneurysm (n = 60) was an expression of the myocardial damage due to the infiltration of the bleeding into the right atrium. Intra-atrial electrogram in 48 patients with various heart diseases revealed that the electric potentials obtained from various parts of the atrium varied to a great extent and finally the patient's condition transformed to that of atrial standstill. We conclude that atrial fibrillation is an expression of some important aspect of the progression of heart disease and is not directly associated with hemodynamic overloading to the atrium. A strategy for quinidine treatment was also introduced.

Age Factors↗
PubMed1987

[Relationships between distribution of disorganized cardiac muscle cells and disease state in hypertrophic cardiomyopathy].

Congestive heart failure is rare in hypertrophic cardiomyopathy (HCM). Therefore, disorganization of the cardiac muscle cells, a histological hallmark of HCM, has not been associated with reduced ventricular contraction. We performed a clinicopathological study of 18 patients with HCM to determine whether disorganization contributes to dilatation and impaired contraction of the ventricles, resulting in affecting the disease condition. The subjects were classified into Group A (11 patients) without dilatation of the ventricular cavities after formalin fixation at autopsy (left 11.9 ml and right 19.1 ml), Group B (two patients) with dilatation of the left but without of the right ventricular cavity (left 31.9 ml and right 25.6 ml), and Group C (five patients) with biventricular dilatation (left 38.6 ml and right 36.8 ml). Various parameters were compared among the three groups. The mean age of the patients was 44.0 years for Group A, 18.5 for Group B and 10.2 section for Group C. The mean cardiothoracic ratio was 51.8% (n = 7) for Group A, 53% (n = 1) or Group B, and 74.0% section for Group C. Obstruction of the left ventricular outflow tract was observed in 100% (n = 8) of the Group A patients, in 0% section of the Group B patients, and in 20.0% section of the Group C patients. The mean left ventricular ejection fraction was 81.0% (n = 5) in Group A, 65.5% in Group B and 39.0% section (n = 2) in Group C. None of the Group A patients had chronic congestive heart failure, whereas all Group C patients died of this condition. Using transverse and longitudinal tissue sections from the ventricles, and a quantitative method employing light microscopy, we determined the area of the myocardium characterized by disorganization and interstitial fibrosis. Septal disorganization was observed in 67.4%, 83.4% and 91.1% section of the transverse sections in Groups A, B and C, respectively, and in 17.0%, 24.9% and 63.5% section of the longitudinal sections in the respective groups. As for the left ventricular free wall, disorganization involved 21.2%, 69.4% section and 90.8% section of the transverse sections and 15.9%, 34.9% section and 38.1% section of the longitudinal sections in Groups A, B and C, respectively. In the right ventricular free wall, there was disorganization in 17.7%, 20.4% and 84.3% section of the transverse sections in 12.4%, 11.5% and 57.0% section of the longitudinal sections in the respective groups.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1986

Purification and structure of 3-methyladenine-DNA glycosylase I of Escherichia coli.

We constructed a recombinant plasmid carrying a gene that suppresses tag mutation. To overproduce its gene product, a 0.8-kilobase DNA fragment which carries the gene was placed under the control of the lac promoter in pUC8. 3-Methyladenine-DNA glycosylase activity in cells carrying such plasmids (pCY5) was 450-fold higher than that of wild type strain, on exposure to isopropyl-beta-D-thiogalactopyranoside. From an extract of such cells, the enzyme was purified to apparent physical homogeneity, and the amino acid composition and the amino-terminal amino acid sequence of the enzyme were determined. The data were in accord with nucleotide sequence of the gene, determined by the dideoxy method. It was deduced that 3-methyladenine-DNA glycosylase I comprises 187 amino acids and its molecular weight is 21,100, consistent with the value estimated from the sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified protein. Only 3-methyladenine was excised from methylated DNA by the purified glycosylase. These results show that the tag is the structural gene for 3-methyladenine-DNA glycosylase I.

Amino Acid Sequence↗
PubMed1986

Structure and expression of the alkB gene of Escherichia coli related to the repair of alkylated DNA.

When the alkB gene of Escherichia coli that controls sensitivity of bacteria to methyl methanesulfonate was placed under the control of the lac regulatory region on a multicopy plasmid, the gene product, AlkB protein, was overproduced. By monitoring the band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the protein was purified to near physical homogeneity. An amino-terminal sequence and total amino acid composition of the purified AlkB protein were in accord with the amino acid sequence deduced from the nucleotide sequence of the alkB gene, determined by the phage M13 dideoxy method. It was concluded that the AlkB protein is comprised of 216 amino acids and has a molecular weight of 23,900. The nucleotide sequence analysis also revealed that the ada and alkB genes are adjacent on the E. coli chromosome and that the first initiation codon for AlkB protein overlaps with the termination codon for Ada protein. We constructed hybrid plasmids carrying an alkB'-lacZ' fusion, with or without the ada control region, and investigated expression of the alkB gene in response to the alkylating agent. We obtained evidence that the ada and alkB genes constitute an operon.

Alkylation↗
PubMed1986

Identification of a DNA segment containing the human DNA polymerase alpha gene.

We isolated a temperature-sensitive mutant from mouse FM3A cells, designated as tsFT20, the DNA polymerase alpha activity of which is heat-labile. A hybrid clone (M6-39 cells) between human cells and tsFT20 cells contained one or two human chromosomes. M6-39 cells (primary hybrid) were exposed to gamma-ray and re-fused with tsFT20, after which we isolated two temperature-resistant secondary hybrids, both of which retained an identical minute portion of the human chromosome, 400-500 kilobase pairs (kbp). Immunological studies demonstrated that this secondary hybrid expressed human DNA polymerase alpha. Thus, the human DNA polymerase alpha gene was located within a DNA region of 400-500 kbp.

Animals↗
PubMed1986

Effects of mechanical trauma of blood cells on dynamic viscoelasticity of blood during clotting.

Effects of mechanical trauma of platelets and red blood cells on dynamic viscoelasticity of blood during clotting were examined. Two different methods were attempted to give the mechanical damage to blood cells. In one method, a flow apparatus consisting of a thin teflon tube and two sample reservoirs connecting to both ends of the tube was employed. After a blood sample repeated the shuttle flow many times through the tube, the dynamic rigidity modulus (G') and loss modulus (G") of the blood sample during clotting were measured. The mechanical trauma of platelets brought about the increase of G' and G" for clots of PRP and whole blood, in addition to shorter clotting time. Slight hemolysis of red blood cells (less than 0.5% of total hemolysis) only yielded shorter clotting time for whole blood. In other method, packed red blood cells were hemolyzed by exposing the ultrasonic wave (the amount of hemolysis was about 5% of total hemolysis). Addition of supernatant of hemolyzed red blood cells to PRP caused the platelet aggregation. Furthermore, a marked hemolysis brought about higher values of G' and G" for blood clot, in addition to shorter clotting time. These results suggest that the release of constituents from damaged red blood cells and alteration of cell surface due to mechanical damage would accelerate the coagulation sequence.

Blood Coagulation↗
PubMed1986

Release of endogenous aspartate and glutamate induced by electrical stimulation in guinea pig cerebellar slices.

Whether endogenous aspartate and glutamate, candidates for the excitatory neurotransmitter of cerebellar climbing and parallel fibers, are actually released from guinea pig cerebellar slices by electrical stimulation of the cerebellar white matter, was examined by means of mass fragmentography using gas chromatograph-mass spectrometer and thin layer chromatography. Both endogenous aspartate and glutamate were found to be significantly released in a Ca- and stimulus-frequency-dependent manner. Although the origin of each amino acid could not be specified in spite of pharmacological attempt to selectively block the mossy fiber-granule cell (parallel fiber) system, these results were at least in favor of the electrophysiologically and pharmacologically suggested candidacy of these amino acids for the transmitters of cerebellar climbing and parallel fibers.

Animals↗