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Biomedical subjects

M Nakazawa

Publications and source records attributed to M Nakazawa.

At least 343 records · Page 19Linked to original sources
PubMed1990

Myocardial perfusion after aortic implantation for anomalous origin of the left coronary artery from the pulmonary artery.

Postoperative myocardial perfusion and function were evaluated using thallium-201 myocardial imaging and technetium-99m cardiac pool imaging in five patients with an anomalous left coronary artery arising from the pulmonary artery. The patients underwent reimplantation of the left coronary artery at an age ranging from 10 months to 13 years. Postoperative electrocardiographic and radionuclide studies were performed both at rest and during stress 1 to 4 years after the operation. Electrocardiograms which were abnormal preoperatively returned to normal after surgery except that the T wave in lead aVL remained negative. Postoperatively, left ventricular ejection fraction measured by technetium-99m cardiac pool imaging was normal in all patients. Postoperative thallium-201 myocardial imaging, however, showed a perfusion defect with incomplete redistribution at the high-lateral or antero-lateral segment in all patients after a stress test. These data suggest that although myocardial ischaemic change decreases and global cardiac function improves after establishment of a dual coronary artery system, severe myocardial damage remains at the high-lateral or antero-lateral segment.

Adolescent↗
PubMed1990

Adrenoceptor-blocking activity and cardiohemodynamic effects of carvedilol in animals.

The beta-blocking activities of a new beta-adrenoceptor blocking drug, carvedilol, evaluated in isolated atria and trachea of the guinea pig were 2.0 (beta 1) and 3.2 times (beta 2), respectively, as potent as those of propranolol. Carvedilol exhibited the alpha-blocking activities in the aorta of guinea pigs and rats. Carvedilol was 2 and 50 times less potent in guinea pigs and rats, respectively, than prazosin as an alpha-blocker. Thus, the alpha-blocking activities were twice as potent as the beta-blocking activity in the rat and one-fifth that of the beta-blocking activity in the guinea pig. In anesthetized open-chest dogs, the beta-blocking activity of carvedilol was 1.5 times more potent than that of propranolol and had 3.8 times the alpha-blocking activity. Thus, carvedilol is a nonselective beta-blocking drug with a potent alpha-blocking activity. Carvedilol and propranolol showed dose-dependent and significant decreases in the blood pressure, total cardiac output, left ventricular pressure, dp/dt, heart rate, coronary flow, and oxygen consumption in anesthetized open-chest dogs. Carvedilol decreased the total peripheral resistance significantly (the decrease was not proportional to the decreases in the blood pressure at high doses), while propranolol increased it significantly and dose-dependently. These results indicate the importance of alpha-adrenoceptor blocking activity in the decrease in blood pressure produced by carvedilol.

Adrenergic alpha-Antagonists↗
PubMed1990

Ventricular volume characteristics in double-inlet left ventricle before and after septation.

Septation is one of the surgical choices for double-inlet left ventricle, yet postoperative hemodynamics have not been well defined. We studied ventricular volume characteristics in 10 patients with double-inlet left ventricle before and after septation. Preoperative end-diastolic volume (EDV) of the ventricle was 291 +/- 111% (+/- SD) of normal and ejection fraction (EF) was 0.59 +/- 0.07. Postoperatively, EDV of the right-sided ventricle (RV) was 82 +/- 24%, and EDV of the left-sided ventricle (LV) was 153 +/- 41%. Ejection fraction of the RV was 0.77 +/- 0.10, and LVEF was 0.49 +/- 0.13. On the short-axis view of two-dimensional echocardiography, fractional change of the cross-sectional area was 0.65 +/- 0.16 for the RV and 0.23 +/- 0.11 for the LV. Fractional shortening of the septum-to-ventricular free wall axis was 0.51 +/- 0.17 in the RV and -0.05 +/- 0.09 in the LV. Analysis of the curvature of the new septum during cardiac cycle on two-dimensional echocardiography revealed that the septum shifted to the right side during systole in all patients in whom the systolic LV/RV pressure ratio was larger than 1.0. The septum shifted toward the LV during diastole in eight patients in whom end-diastolic pressure in the RV was higher than or equal to that in the LV, whereas it remained in the right side in two patients with higher left-side pressure. The cardiac index of these two patients was 2.4 and 2.6 l/min/m2, respectively, whereas it averaged 4.4 +/- 1.0 l/min/m2 in the other eight patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Effect of atrial natriuretic peptide on hemodynamics of the stage 21 chick embryo.

Atrial natriuretic peptide (ANP) is important in the modulation of hemodynamics and fluid balance in the mature subject, but its hemodynamic effects at early stages of morphogenesis are not defined. We studied the effect of rat atriopeptin III on hemodynamics in chick embryos at Hamburger-Hamilton stage 21. The cardiovascular system is not yet innervated, nor is the kidney formed in these embryos. The vitelline arterial and venous blood pressures were measured with a servo-null, micro-pressure system and the dorsal aortic blood flow was measured with a 20 MHz pulsed Doppler velocity meter. The peptide was infused into the vitelline vein with a microinjector at doses of 0.1, 1.0, and 10 ng. Doses normalized by body wt of embryos averaged 0.003, 0.035, and 0.32 ng/mg (n = 61), respectively. Vitelline arterial blood pressure decreased in a dose dependent manner [y = 55.8 - 9.9x; r = -0.49; p less than 0.01 (y = % of baseline, x = log ng/mg)], and dorsal aortic blood flow, a measure of cardiac output, decreased similarly (y = 39.6 - 16.2x; r = -0.47; p less than 0.01). Heart rate did not change. Ten ng of ANP increased the vitelline venous diameter, determined directly under a microscope, from 125 +/- 47 (SD) microns to 139 +/- 49 microns (n = 11; p less than 0.01), and decreased vitelline venous pressure from 0.34 +/- 0.05 mm Hg to 0.10 +/- 0.07 mm Hg (n = 5). We conclude that ANP exerts its hemodynamic effect by direct venodilation in the noninnervated and anephric circulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Effects of calcium antagonists, felodipine and nicardipine, on cerebral circulation in dogs.

The effects of a calcium antagonist of the dihydropyridine type, felodipine, on the cerebral circulation were studied in comparison with those of nicardipine in pancuronium-bromide immobilized unanesthetized dogs. Felodipine (0.3-10 micrograms/kg, i.v.) and nicardipine (0.3-10 micrograms/kg, i.v.) produced a dose-related decrease in mean blood pressure with almost equal potencies. However, at a dose of 3 micrograms/kg, felodipine produced a more prominent increase in cerebral blood flow (CBF) than nicardipine. Decreases in cerebral vascular resistance were significantly greater in the felodipine group at doses of 0.3 and 3 micrograms/kg, when compared with the nicardipine group. Cerebral oxygen consumption calculated by multiplying the arterio-venous difference of oxygen content by CBF was increased by these two drugs, but the changes were minimal. These data suggest that the increase in CBF produced by felodipine and nicardipine was primarily due to the direct dilatation of the cerebral blood vessels.

Animals↗
PubMed1990

[Chronic idiopathic neutropenia improved by recombinant granulocyte colony stimulating factor].

A 55-year-old man was admitted to our hospital for the evaluation of neutropenia. On physical examination, he had apthae and splenomegaly. CBC showed 1,000/microliter WBC with 5% neutrophils, and microcytic anemia consistent with iron deficiency. Bone marrow examination revealed a marked decrease of mature neutrophils, but normal percentage of immature myeloid cells. There was no morphological abnormality in the hemopoietic cells. He had no drug or family history responsible for the neutropenia. Anti-neutrophil auto-antibody was negative. Hence, a diagnosis of chronic idiopathic neutropenia (CIN) was made. He developed frequent episodes of infection such as balanitis, peri-anal infection, gingivitis, and pharyngitis. He was treated with steroid pulse therapy, anabolic hormone, and high dose gamma-globulin infusion, but no significant improvement occurred. Then, recombinant granulocyte-colony stimulating factor (rG-CSF) was started. The neutrophil count was normalized by the 7th day of 5 micrograms/kg/day rG-CSF administration. The administration of G-CSF was discontinued after a 14-day course. Thereafter, the neutrophil count remained at near normal level (approximately 1,500/microliter) and there have been no episodes of infection in the last 5 months. However this cannot be explained simply by the direct effect of rG-CSF on the myeloid precursors; rather, it suggests some unknown effect of G-CSF on the bone marrow microenvironment regulating myeloid hemopoiesis. We consider this to be a rare case of CIN with frequent episodes of infection, which was successfully treated with G-CSF.

Agranulocytosis↗
PubMed1990

Immunoperoxidase evaluation of the relationship between necrotic lesions and causative bacteria in lungs of calves with naturally acquired pneumonia.

An immunoperoxidase technique was used to study the relationship between the necrotic lesions and causative bacteria found in lungs of 53 calves that had naturally acquired pneumonia. Four types of necrotic lesions were identified on the basis of morphologic characteristics as follows: type 1 had coagulation necrosis surrounded by a dense zone of numerous degenerated leukocytes; type 2 was similar to type 1, but the central area of the lesions was severely affected, had no alveolar architecture remaining, and was surrounded by a thin, sparse layer of degenerated leukocytes; type 3 had small swirling accumulation of degenerated leukocytes; and type 4 had necropurulent lesions resembling abscesses. By use of the immunoperoxidase technique, Pasteurella haemolytica serovar 1 antigen was confirmed to be associated with the necrotic lesions in many cases of type 1 and in some cases of types 2 and 3. Although some lesions were induced by other bacteria (Haemophilus somnus or Actinomyces pyogenes), the pneumonic lesions associated with P haemolytica could be differentiated from other pneumonic lesions in calves by use of the immunoperoxidase technique.

Age Factors↗
PubMed1990

Histopathologic findings of endomyocardial biopsies in pediatric patients with arrhythmias or conduction disturbances.

Histopathologic findings of endomyocardial biopsy in 23 pediatric patients with arrhythmias or conduction disturbance were analyzed. ECG abnormalities consisted of atrioventricular block (AVB) in 11, ventricular arrhythmia including premature ventricular contractions (PVC) and ventricular tachycardia in 7, sick sinus syndrome (SSS) in 3, and bundle branch block in 2 cases. Biopsy specimens were obtained from the right ventricle in all cases and, additionally, from the right atrium in SSS cases. Biopsy revealed significant pathology in 19 cases (83%). Advanced histologic changes, including myocyte hypertrophy, disarrangement of muscle bundles, and interstitial fibrosis with or without myocyte degeneration, were observed in 7/11 AVB cases and 1/6 PVC cases. SSS cases showed interstitial fibrosis with disarrangement of muscle bundles in the right atrium, but no significant pathologic changes were seen in the right ventricle. There was no clinical evidence of hypertrophic or dilated cardiomyopathy, cardiac defects, or other heart disease in these patients. It is suggested that these cases may fall under the arrhythmia-conduction disturbance type of cardiomyopathy.

Adolescent↗
PubMed1990

Immunohistochemical study on human atrial natriuretic polypeptide in the ventricle of hearts with endocardial fibroelastosis.

The presence and distribution of human atrial natriuretic polypeptide (ANP) were investigated immunohistochemically in the ventricles of hearts of 14 cases with endocardial fibroelastosis and 15 cases with noncardiac disease in children. Paraffin sections of autopsied hearts with endocardial fibroelastosis were stained with polyclonal antibodies against human alpha-ANP. Immunoreactive myocytes were clearly demonstrated in the ventricles of 10 hearts with endocardial fibroelastosis. The distribution of ANP-positive cells was most frequent in the inner one-third of the left ventricle. No ANP immunoreactivity was detected in any heart in cases with noncardiac disease. The left ventricular volume index of hearts with ANP-positive cells was larger than that with ANP-negative cells. The mean diameter of ANP-positive myocytes was greater than that of ANP-negative myocytes. These results suggest that ANP expression in ventricular myocytes is related to severe dilatation of the ventricular cavity and to development of myocardial hypertrophy in endocardial fibroelastosis.

Atrial Natriuretic Factor↗
PubMed1990

[The relationship between responsiveness to splenectomy and clinical course after splenectomy in chronic idiopathic thrombocytopenic purpura (ITP)].

Fifty-four ITP patients were treated by the protocol proposed by Japanese Idiopathic Disease of Hematopoietic Organ Research Committee. Forty-eight patients were treated with corticosteroid (CS). Twenty-eight patients out of 30 patients who were refractory to CS were splenectomized. To study natural courses of splenectomized patients, 25 patients were splenectomized without elevation of platelet counts at the operation and were followed up their platelet counts and PAIgG for one month without treatment. Clinical courses after splenectomy were classified into four types by the platelet increment followed by splenectomy and the platelet counts at one month after splenectomy; type I (markedly over-shooted platelet peak and normalized platelet counts), type II (moderate platelet peak and 50 approximately 100 x 10(3)/microliters platelets), type III (minimal platelet peak and less than 50 x 10(3)/microliters platelets), and type IV (elevation of platelet counts at day 7 or later of splenectomy and normalized platelet counts). The results of analyses from 25 patients indicated that the numbers of type I, II, III and IV were 10, 5, 6 and 4, respectively. The clinical course of type IV suggests that platelet production may be impaired by anti-platelet antibodies.

Adult↗
PubMed1990

Septation and Fontan repair of univentricular atrioventricular connection.

From April 1986 to September 1988, 12 patients with double- or common-inlet left ventricle and left anterior rudimentary right ventricle underwent septation while 17 patients with double- or common-inlet left or right ventricle underwent the Fontan operation. In the septation group, three patients who had pressure gradients ranging from 10 to 85 mm Hg between the left ventricle and the aorta underwent enlargement of the outlet foramen, and all survived. One of the 12 patients had a common atrioventricular valve that was repaired by separating the atrioventricular valve by the procedure used for atrioventricular septal defect. One had complete heart block before septation and the other one had it after separation. One 17-year-old woman, who had the smallest left ventricle (168% of normal), died in the hospital (mortality, 8.3%). In the Fontan group, one patient who died in the hospital (5.9%) had high pulmonary resistance of 4.4 U/m2, and one late death (5.9%) occurred in a patient who had complete heart block and a high mean pulmonary arterial pressure of 20 mm Hg. Because of suprasystemic pressure in the pulmonary ventricle, two patients had immediate takedown of the septation repair and substitution of the Fontan repair. Although right atrial pressure was almost equal in both groups after operation, the cardiac index was significantly higher in the septation group than in the Fontan repair group (p less than 0.01). These data suggest that patients who are candidates for either septation or Fontan repair might fare better with septation.

Adolescent↗
PubMed1990

[Left ventricular function after Konno procedure for congenital aortic stenosis].

From February, 1984 to September, 1988, eighteen patients with congenital aortic stenosis underwent Konno procedure. There was no operative death, but one late death (5.6%). The annular diameter ranged from 9 mm to 23 mm (mean 15 mm). Preoperative left ventricular ejection fraction (LVEF) measured by cineangiography ranged from 0.59 to 0.92 (mean 0.77) and half of the patients had more than 0.80 of LVEF. Left ventricular function after the operation was evaluated at rest or during exercise by radionuclide ventriculography. Postoperative LVEF ranged from 0.59 to 0.89 (mean 0.75). Although there were no statistically significant changes between preoperative and postoperative LVEF, there was a trend that preoperative supernormal LVEF improved to normal after surgery. The response to exercise also improved in some cases after surgery. We concluded that Konno procedure can be safely undertaken with improvement of left ventricular function.

Adolescent↗
PubMed1990

[Pentatrichomonas hominis from beagle dogs--detection method, characteristics and route of infection].

Pentatrichomonas sp. from the feces of beagles was cultured axenically, and identified as P. hominis. The culture medium used was slightly modified Diamond's medium supplemented with chicken liver extract and rifampicin. Based upon good proliferation after inoculating only a few organisms in this medium, a fecal examination method employing cultivation was developed. Resistance of the trichomonad against disinfectants and metronidazole was tested, and it was found that the protozoan was rather susceptible. After oral administration of the organism to mice and rats, all the treated animals were infected. Since two types of the trichomonad, moving and non-moving, were detected, the presence of any type resistant to standing or drying was ruled out. A possible route of trichomonad infection to beagles is discussed.

Animals↗
PubMed1989

Structure of the promoter region and tissue specificity of the human glycophorin C gene.

Glycophorin C (GPC) is an integral membrane protein of human erythrocytes which plays an important role in regulating the deformability and mechanical stability of red cells. Recently, the structural gene for this glycoprotein has been cloned (Colin, Y., Le Van Kim, C., Tsapis, A., Clerget, M., d'Auriol, L., London, J., Galibert, F., and Cartron, J. P. (1989) J. Biol. Chem. 264, 3773-3780), and we have now determined the sequence of the 1050 base pairs of DNA preceding the transcription initiation site mapped in erythroid cells. This region contains different potential regulatory cis-acting elements found in a variety of eukaryotic promoters (TATA box, CAAT box, Sp1-binding site) as well as sequences present in the promoter and enhancer regions of genes specific for the erythroid lineage (CACCC box and NF-E1-binding site). Northern blot analysis and immunological studies indicate that the GPC gene is expressed in a large number of cells and tissues. However, the level of transcription as well as the glycosylation of the mature GPC differ in erythroid and nonerythroid cells. Primer extension analysis and mapping of the 5' end GPC mRNA by the polymerase chain reaction indicate that different transcription sites are utilized for the expression of the GPC gene in erythroid and nonerythroid tissues and cell lines.

Base Sequence↗
PubMed1989

KU 812: a pluripotent human cell line with spontaneous erythroid terminal maturation.

A human leukemic cell line KU 812 was recently established and described as a basophilic cell line. In the present study we show that KU 812 and two of its clones are at least bipotent: in addition to a minor component of basophils, the majority of KU 812 cells belongs to the erythroid cell lineage with a significant percentage (about 15%) of mature hemoglobinized erythroblasts. This terminal differentiation is associated with the synchronized synthesis of the main erythroid proteins, including glycophorins, spectrin beta chain, band 3, and hemoglobin. The predominant hemoglobins are adult, fetal, and Bart's hemoglobin. Adult hemoglobin represented up to 75% of all hemoglobins in the KU 812 F clone in passages containing a high number of mature erythroblasts. Transcripts of all human globin chains were present with ten times less embryonic chain messenger RNA (mRNA) than alpha-, beta- or gamma-chain mRNA. Hemin slightly increased the total hemoglobin production of the cell line, especially gamma-globin chain synthesis, but did not modify the percentage of hemoglobinized cells. Phorbol myristate acetate (PMA) had a complex effect, inducing a proportion of KU 812 cells to adhere to the plastic culture flask. The adherent cell fraction expressed a very low level of specific erythroid proteins, but their ultrastructure was consistent with immature erythroid cells. In contrast, approximately 40% of the nonadherent cells were mature erythroid cells. Cell-sorting experiments showed that this paradoxic effect of PMA is mostly due to cell selection, the more mature cells being unable to adhere. In addition, KU 812 F was found to be sensitive to erythropoietin, which slightly increased its plating efficiency range (from 0% to 50%) in semisolid medium and enhanced hemoglobin accumulation twofold. In binding experiments using 125I erythropoietin, a single class of high-affinity Epo receptors (Kd: 250 pM) was detected by binding with a density of 205 receptors per cell. The KU 812 cell line is therefore a unique model for studying cell commitment toward different hematopoietic lineages and erythroid differentiation.

Antigens, Differentiation↗