Biomedical subjects

K Momma

Publications and source records attributed to K Momma.

At least 127 records · Page 7Linked to original sources

PubMed1992

Hypoplasia of the lung and heart in fetal rats with diaphragmatic hernia.

We studied 11 fetal rats with normal heart and diaphragmatic hernia induced by administration of bis-diamine (200 mg) on the 9th and 10th day of pregnancy. After rapid whole-body freezing on the 21st day, the fetuses were studied by means of serial cross-sectional photographs of the frozen thorax. In the fetuses with hernia, the left half of the diaphragm was completely absent, and the liver and stomach were in the left hemithorax. The lung and heart were hypoplastic in fetal diaphragmatic hernia. Cardiac volume reduction involved all four chambers and was more prominent in the left atrium and ventricles. The great vessels were also smaller.

Abnormalities, Multiple↗

PubMed1992

HCO3(-)-dependent intracellular pH regulation in the premature myocardium.

This study investigated developmental changes in Na(+)-H+ exchange and HCO3(-)-Cl- exchange activities in newborn and adult rabbit hearts. pHi was measured using the fluorescent dye 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein in isolated myocytes. Myocardial mechanical function was measured in the isolated ventricular preparation. Intracellular acidosis with normal pHo was induced by an NH4Cl (10 mM) prepulse technique. Upon removal of NH4Cl, pHi fell transiently and then recovered toward the control level. In the HCO3-/CO2-buffered solution, the rate of recovery of pHi in the newborn was greater than in the adult. In the HCO3-/CO2-buffered solution, 5-(N-ethyl-N-isopropyl)amiloride (EIPA), an inhibitor of Na(+)-H+ exchange, inhibited the recovery of pHi completely in the adult. In the newborn, however, significant recovery of pHi was observed in the presence of EIPA. In the presence of both EIPA and 4-acetamido-4'-isothiocyanatostilbene-2',2'-disulfonic acid (SITS), an inhibitor of HCO3(-)-Cl- exchange, the recovery of pHi was not observed in the two age groups. In the HEPES-buffered solution that did not contain HCO3-/CO2, the rate of recovery of pHi after NH4Cl removal was similar in the two age groups. In the HEPES-buffered solution, the recovery of pHi was completely inhibited by EIPA in the two age groups. In the presence of EIPA in the HCO3-/CO2-buffered solution, contractile function decreased during acidosis after NH4Cl removal and did not recover in the adult. In the newborn, significant recovery of contractile function was observed after NH4Cl removal in the presence of EIPA. The recovery of mechanical function observed in the presence of EIPA in the newborn was inhibited by SITS. These data suggest that, although there is no developmental change in the Na(+)-H+ exchange activity, HCO3(-)-Cl- exchange is more active in the premature myocardium. The presence of the HCO3(-)-Cl- exchanger is important in maintaining myocardial contractile function during acidosis, especially when Na(+)-H+ exchange is inhibited and may partly explain the greater resistance of the premature myocardium to acidosis.

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗

PubMed1992

In situ morphology of the ductus venosus and related vessels in the fetal and neonatal rat.

In situ cross-sectional morphology of the ductus venosus and related vessels was studied after rapid whole-body freezing of the fetal and neonatal rat. In the fetus, the ductus venosus was open widely, connecting the umbilical sinus and the inferior vena cava. The diameter of the ductus venosus was 50% of the diameter of the umbilical sinus. The ductus venous joined the left dorsal side of the inferior vena cava. A thin, short, membrane-like edge was present at the inner junction of the ductus venosus and the inferior vena cava, presumably effecting laminar flow of the ductus venosus blood to the left side of the thoracic inferior vena cava. A very prominent eustachian valve was present at the junction of the inferior vena cava and the right atrium, presumably directing its flow to the opening of the foramen ovale. After birth, the ductus venosus narrowed rapidly and closed completely in 2 d. The closing ductus venosus was tubular, with the cranial end slightly wider than the caudal portion. Localized constriction was not present. These observations showed the structural substrate for preferential flow from the ductus venosus to the foramen ovale and left atrium in the fetus and did not support localized sphincter mechanism in postnatal closure of the ductus venosus.

Animals↗

PubMed1992

In situ morphology of the foramen ovale in the fetal and neonatal rat.

In situ cross-sectional morphology of the foramen ovale was studied after rapid whole-body freezing of the fetal and neonatal rat. In the fetus, the foramen ovale was open widely toward the left atrium with a thin, short primum septum. The opening area of the foramen ovale was 40% of the cross-section of the thoracic inferior vena cava, and the ratio of the long diameter to the short diameter was 2 to 1. After birth, the primum septum became longer, thicker, and straighter, with less leftward bowing. The opening of the foramen ovale diminished in the first 2 d and closed completely 3 d after birth. Postnatal thickening of the primum septum was very remarkable, increasing by 400% in the first 2d, while only minimal change was noticed in the right and the left atrial walls. The length of the primum septum was short and was only 90% of the diameter of the fossa ovalis in the fetus. It increased and reached 97% and 111% of the diameter of the fossa ovalis 1 and 2 d after birth, respectively. The septum secundum also grew rapidly after birth, and its length and width increased by 40% and 29% after 1 and 2 d, respectively. These observations indicate a sudden, explosive growth of the atrial septum in the early neonatal period in the rat.

Age Factors↗

PubMed1992

Prediction of surgical result of valve replacement for chronic isolated mitral regurgitation--the significance of preoperative estimation of postoperative left ventricular afterload.

Left ventricular (LV) afterload increases after mitral valve replacement, thus it would be useful to estimate postoperative LV afterload before surgery. We tested the usefulness of an index, wall stress, obtained from preoperative end-diastolic LV dimensions and diastolic blood pressure which would represent LV afterload after surgery. The data were compared with surgical mortality and morbidity. The wall stress ranged from 98 to 220 kdynes/cm2 and was 202 or higher in 3 patients who died. Five patients had wall stress above 200 kdynes/cm2. Among these, intra-aortic balloon pumping (IABP) was used in 4, and 3 died. Prolonged catecholamine support for greater than 10 days was given to all of the 4 patients, including two who died 14 and 23 days after surgery. Among 38 patients who had wall stress less than 200 kdynes/cm2, none died, IABP was performed in 3 patients, and prolonged catecholamine infusion was required in 5 patients. The incidence of mortality and morbidity were significantly higher in the high stress than in the low stress group (Chi-square analysis). Left ventricular end-diastolic index was larger in the high stress than in the low stress group (p less than 0.05). The mass/end-diastolic volume ratio was smaller in the high stress group than in the low stress group (P less than 0.05). In conclusion, this new index, predictive wall stress, is useful in selecting patients who would have high mortality and morbidity.

Cardiac Catheterization↗

PubMed1991

Effect of partial Na pump and Na-H exchange inhibition on [Ca]i during acidosis in cardiac cells.

This study investigated the effects of partial Na pump inhibition and Na-H exchange inhibition on contractile function, intracellular pH (pHi), and intracellular Ca concentration ([Ca]i) during intracellular acidosis, using the fluorescent dyes 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein and fura-2 in isolated cardiac cells of adult rabbits. Intracellular acidosis with normal extracellular pH was induced by an NH4Cl (10 mM) prepulse technique. A nontoxic concentration (0.5 microM) of ouabain was used to inhibit the Na pump. 5-(N-ethyl-N-isopropyl)amiloride (EIPA) was used to inhibit Na-H exchange. In both the absence and presence of ouabain, pHi fell transiently and then recovered after removal of NH4Cl. Ouabain did not alter the pHi changes observed after removal of NH4Cl. Diastolic and systolic [Ca]i increased during acidosis after NH4Cl removal. In the presence of ouabain, the increase in [Ca]i during acidosis was greater than that in the absence of this drug. Ouabain enhanced the recovery of contractile function during acidosis. In both the absence and presence of ouabain, Na-H exchange inhibition by EIPA reduced the recovery of pHi and mechanical function and the increase in [Ca]i, which were normally observed after NH4Cl removal. These data suggest that in adult rabbit myocytes the Na pump inhibition enhances the increase in [Ca]i during acidosis, and the Na-H exchange inhibition reduces it. The [Ca]i increase during acidosis may be in part due to the altered Na-Ca exchange, which in turn results from the increased Na-H exchange.

Acidosis↗

PubMed1991

Fetal cardiovascular morphology of truncus arteriosus with or without truncal valve insufficiency in the rat.

BACKGROUND: Recent advances in fetal echocardiography have necessitated further study on fetal in situ cardiovascular morphology of truncus arteriosus and the effects of truncal valve insufficiency. METHODS AND RESULTS: We studied 55 fetal rats with truncus arteriosus among 300 fetuses from 40 virgin females treated with 200 mg fertilysin on the 10th day of pregnancy. After rapid whole-body freezing on the 21st day, the fetuses were studied by means of serial cross-sectional photographs of the frozen thorax. Thirty-five fetuses with a normal heart treated with fertilysin served as controls. Truncus arteriosus was characterized by a large ventricular septal defect, a solitary artery (truncus arteriosus) overriding the ventricular septum, the right and left pulmonary arteries originating from the truncus arteriosus with or without a common trunk (main pulmonary artery), and absent ductus arteriosus. Fetuses with truncal valve insufficiency had thick truncal valves, a large truncus arteriosus, and large ventricles. The subgroup of 12 fetuses with a large truncus (truncal diameter greater than 160% of the ascending aorta diameter in the controls) showed significantly greater values for right ventricular volume (200% of control) and mass (120% of control), left ventricular volume (170% of control) and mass (110% of control), right (120% of control) and left (110% of control) atrial volume, and pericardial fluid (140% of control) than the controls. These changes were less prominent and ventricular volumes were not increased in the remaining subgroup with a truncal diameter of 160% or less of aorta diameter in the controls. CONCLUSIONS: In fetal truncus arteriosus, truncal valve insufficiency was associated with increased ventricular volume load and incomplete cardiac compensation in rats.

Abnormalities, Multiple↗

PubMed1991

Natural histories of atrial septal defect with pulmonary hypertension, and ventricular septal defect with pulmonary hypertension.

A study of the natural history of 51 adult patients with atrial septal defect with pulmonary hypertension (ASD + PH) was performed. ASD + PH of less than 14 Um2 of pulmonary artery resistance (PVR) was considered an indication for surgery. The prognosis of surgically treated patients was favorable, but that of medically treated patients was poor. For patients with ventricular septal defect with pulmonary hypertension (VSD + PH), surgery was considered for pulmonary-systemic vascular resistance ratio (Rp/Rs) less than 0.5, and for patients under than 10 years and, ideally, under 2 years of age.

Adult↗

PubMed1990

Characteristics and natural history of abnormal atrial rhythms in left isomerism.

The object of this study is to document variation in atrial pacemaker rate and P-wave axis, and to clarify the natural history of abnormally slow atrial rhythms in left isomerism. Standard 15-lead electrocardiograms of 50 patients with left isomerism were retrospectively studied. On the average, 9 electrocardiograms covering 7 years for each patient were available. For comparison, atrial rhythms in patients with right isomerism and in those with situs solitus and 5 representative congenital cardiac conditions were studied with the same study protocol. In left isomerism, atrial rhythm with constantly normal P-wave axis was exceptional and the presence of atrial rhythm with abnormal P-wave axis was the rule. The most frequent abnormal mean frontal P-wave axis was between -30 and -90 degrees, recorded in 70%. Slow atrial rates below the second percentile were observed in 50%, either transiently and recurrently (in 40%), or persistently (in 10%), and were associated with junctional escape in 42%. The number of patients with slow atrial rate increased with age. In right isomerism, multiple atrial rhythms were also frequent, but slow atrial rhythms was present in only 4%. Multiple atrial rhythms or bradycardia associated with junctional escape were rare in the group of patients with congenital heart disease and situs solitus. It is concluded that multiplicity and progressive slowing of the atrial rhythm are characteristic in patients with left isomerism.

Abnormalities, Multiple↗

PubMed1990

Ostial stenosis of the left coronary artery as a sole clinical manifestation of Takayasu's arteritis: a possible cause of unexpected sudden death.

An 11-year-old girl experienced several syncopal attacks and her electrocardiogram showed ST depression with exercise. Ostial stenosis of the left coronary artery was disclosed by the coronary angiography. We suspected the coronary involvement was due to Takayasu's arteritis. On operation, aortitis in the ascending aorta involving ostium of the left coronary artery was observed. Therefore Takayasu's arteritis is considered to be one of the causes of sudden death.

Aortic Arch Syndromes↗

PubMed1990

Abnormal development of fourth aortic arch derivatives in the pathogenesis of tetralogy of Fallot.

Aortic arch (AoA) anomalies were studied in 233 patients with tetralogy of Fallot (TOF) of whom some had coexisting pulmonary atresia (PA). There was a 23% incidence of a right AoA in patients without PA, 21% in those with both PA and persistent ductus arteriosus (PDA), and 50% in those with PA and major aortopulmonary collateral arteries (MAPCAs). There was a 5% incidence of an aberrant subclavian artery in patients without PA and a 16% incidence in those with PA and MAPCAs. In this cohort an elongated ascending aorta was observed both with and without high aortic arch. These aortic arch anomalies were frequently associated with PA and MAPCAs.

Adolescent↗

PubMed1990

Transplacental cardiovascular effects of four popular analgesics in rats.

The purpose of this study is to clarify fetal cardiovascular effects of four popular analgesics administered to a maternal animal model. Clinical doses of aspirin (14 mg/kg), acetaminophen (14 mg/kg), ibuprofen (6 mg/kg), or indomethacin (0.7 mg/kg) were administered orally to near-term rats. At 1, 4, 8, or 24 hours later fetuses were delivered by cesarean section, and were fixed immediately by the whole-body freezing technique. The ductus diameter, pericardial effusion, and volume and mass of the ventricles were studied by photographing multiple planes of the heart. Fetal ductal constriction was most remarkable with ibuprofen, with the diameter decreased 70% +/- 5% (mean +/- SEM) at 1 to 8 hours. Both ventricles were dilated 60% +/- 27%, and pericardial fluid was increased 120% +/- 20%. These changes partly disappeared at 24 hours. Milder but more persistent effects were observed with indomethacin. The fetal ductus was constricted 30% at 4 to 24 hours. Pericardial fluid was increased 140% +/- 30% at 24 hours. Aspirin and acetaminophen constricted the fetal ductus 10%. In conclusion, clinical doses of ibuprofen and indomethacin constricted the fetal rat ductus and caused cardiac failure. The effects of aspirin and acetaminophen were much milder.

Acetaminophen↗

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

Fetal cardiovascular cross-sectional morphology of tetralogy of Fallot in rats.

In order to clarify cross-sectional morphology of tetralogy of Fallot in the fetus, 202 rat fetuses with tetralogy of Fallot induced by maternal administration of bis-diamine were studied using cesarean section, the whole body freezing method and by photographing cross sections of the fetal heart on a freezing microtome. Some characteristic features such as large subaortic ventricular septal defects, aortic overriding over the ventricular septum, aortomitral fibrous continuity, and narrow infundibulum and pulmonary valve were found. Moreover, three subtypes were noticed. In classic tetralogy of Fallot with stenotic infundibulum, the size of the pulmonary arteries was smaller in proportion to the infundibular stenosis. In the second type with absent infundibular septum and severe valvular pulmonary stenosis, the pulmonary arteries were most hypoplastic. In the third type with absent pulmonary valve, the pulmonary arteries were dilated forming aneurysms. In the last type only, ventricles were dilated and grossly hypertrophic.

Animals↗

PubMed1990

Fetal cardiac morphology of tetralogy of Fallot with absent pulmonary valve in the rat.

Fetal in situ cardiovascular and bronchial morphologies were studied in rats with tetralogy of Fallot and absent pulmonary valve to clarify the prenatal pathology of this complex. There were 42 fetal rats with this complex among 300 fetuses treated with N,N'-bis-(dichloroacetyl)-1,8-octamethylenediamine (bis-diamine) (200 mg) on the 10th day of pregnancy. After undergoing rapid whole-body freezing on the 21st day, they were studied by means of serial cross-sectional photographs of the frozen thorax. Fetuses with normal heart treated with bis-diamine served as control. Tetralogy of Fallot and absent pulmonary valve in the fetus was associated with absence of the ductus arteriosus, enlargement and hypertrophy of both ventricles, and enlargement of the pulmonary arteries that compressed the bronchial trees. These abnormalities were inversely correlated with the degree of pulmonary stenosis. Milder stenosis (pulmonary valve ring greater than 50% of control, n = 28) was associated with larger pulmonary arteries (250 +/- 12% of control) (mean +/- SEM) and larger ventricles (volume, 200 +/- 15%; mass, 130 +/- 4%). Severe stenosis (pulmonary valve ring less than 50% of control, n = 14) was associated with mildly enlarged pulmonary arteries and mild bronchial compression. We concluded that enlargement of the pulmonary arteries and bronchial compression develop in fetal life and are associated with mild pulmonary stenosis in tetralogy of Fallot and absent pulmonary valve.

Animals↗

PubMed1989

Right ventricular concentric hypertrophy and left ventricular dilatation by ductal constriction in fetal rats.

Fetal cardiac changes due to ductal constriction by maternal ingestion of nonsteroidal anti-inflammatory drugs were studied morphologically in near-term rats as an animal model, and results were compared with values of control 1 (C1, twenty-first day) and control 2 (C2, twenty-second day). The fetal ductus was constricted (-70%) (p less than 0.05) by maternal administration of 10 mg/kg indomethacin. Dilatation of the right ventricle and evidence of congestive heart failure including increased pericardial effusion (+200%) (p less than 0.05) and an increase in water content in the abdominal wall were present at 1, 4, and 8 hours after drug administration. At 24 hours after drug administration, concentric right ventricular hypertrophy was shown by a diminished right ventricular cavity (-36% vs. C2) (p less than 0.05), increased right ventricular wall thickness (+70% vs. C2) (p less than 0.05), and increased right ventricular mass (+31% vs. C1) (p less than 0.05). Left ventricular dilatation was indicated by an increased cavity volume (+87% vs. C2) (p less than 0.05) and increased muscle mass (+29% vs. C1 [p less than 0.05] or +9% vs. C2 [p greater than 0.05]). Both the wet and dry weights of the ventricles were increased. In conclusion, fetal ductal constriction caused right ventricular hypertrophy, diminished right ventricular cavity, and left ventricular dilatation and hypertrophy at 24 hours after drug administration in rats after initial congestive failure.

Animals↗

PubMed1989

Increased constriction of the ductus arteriosus with combined administration of indomethacin and betamethasone in fetal rats.

To find a better treatment for patient ductus arteriosus of preterm infants, we studied the combined effect of indomethacin and betamethasone on the fetal ductus in rats. We used a rapid whole-body freezing technique, and the ratio of the inner diameter of the ductus to the main pulmonary artery, which was 1.0 in controls, was used as an index of constriction. Indices of ductal constriction 4 h after administration of indomethacin (1 mg/kg) alone, betamethasone (1 mg/kg) alone or in combination in near-term rats were 0.56 +/- 0.05 (mean +/- SEM), 0.76 +/- 0.06, and 0.17 +/- 0.03, respectively. In preterm rats too, a marked increase in fetal ductus constriction was observed with the combined administration of these two drugs. Study of the dose effect of betamethasone revealed that maximal effects were obtained with 1 mg/kg of betamethasone combined with indomethacin in both preterm and near-term fetal rats. Increased constriction of the fetal ductus with combination treatment persisted from 1 to 8 h after administration. Administration of betamethasone 24 h before the rat was killed did not augment constriction of the fetal ductus by indomethacin administered 4 h before they were killed. Fetal ductus constriction by sulindac, another nonsteroidal antiinflammatory drug with little inhibitory effect on renal function, also was augmented by combined use with betamethasone (1 mg/kg). In conclusion, ductal constriction was markedly increased by combined administration of indomethacin and betamethasone in near-term and preterm fetal rats.

Animals↗

PubMed1989

Fetal cardiovascular effects of nifedipine in rats.

In this study we clarify the fetal cardiovascular effects of nifedipine. Nifedipine was administered to near-term rats and cardiovascular morphology of the fetus was studied with a rapid whole-body freezing technique. Fetal cardiac failure was estimated by accumulation of pericardial effusion and ventricular dilatation. Dose-response study at 8 h after administration revealed that slight ventricular dilatation occurred with 0.1 mg/kg of nifedipine, and remarkable ventricular dilatation and pericardial fluid accumulation were noted with 10 mg/kg nifedipine. Time-course study with one dose of 10 mg/kg nifedipine revealed early ventricular dilatation at 1 h, peak ventricular dilatation and fluid accumulation at 8 h, and slight effects at 24 h. In conclusion, the cardiodepressive effect of nifedipine in the fetal rat was mild with the therapeutic dose, and its effects increased dose dependently.

Animals↗