Biomedical subjects

H Sakamoto

Publications and source records attributed to H Sakamoto.

At least 397 records · Page 22Linked to original sources

PubMed1996

An anatomical analysis of the relationships between the intercostal nerves and the thoracic and abdominal muscles in man. II. Detailed analysis of innervation of the three lateral abdominal muscles.

Minute dissection was performed in one male adult cadaver in order to elucidate the detailed distribution of muscular branches of intercostal nerves within the lateral abdominal muscles as well as the segmental relationships. In the obliquus internus and transversus abdominis, as well as in the upper half of the obliquus externus, each muscle fascicle receives the nerve of the corresponding segmental attachment to the rib. On the other hand, in the lower half, the obliquus externus abdominis receives a twig from the lower adjacent segmental nerve, because within the muscle the corresponding segmental nerve first runs horizontally and enters the upper adjacent fascicle before descending obliquely, parallel to the fiber direction.

Abdominal Muscles↗

PubMed1996

Myocardial infarction in myxoma patients with normal coronary arteries. Case reports.

Three cases of patients with cardiac myxoma who had attacks of acute myocardial infarction are presented. Cineangiographic study showed normal coronary arteries. Immunohistochemical and serologic examination revealed that both interleukin-6 and interleukin-8 were secreted in cardiac myxoma. The authors discuss the relation between these cytokines and myocardial infarction with normal coronary arteries.

Adult↗

PubMed1996

Abnormal Q wave, ST-segment elevation, T-wave inversion, and widespread focal myocytolysis associated with subarachnoid hemorrhage.

A 74-year-old Japanese woman with subarachnoid hemorrhage was admitted to our hospital. During her hospitalization, serial electrocardiograms showed the combination of abnormal Q waves, ST-segment elevation, and T-wave inversion, which strongly suggested acute myocardial infarction. However, postmortem examination revealed widespread focal myocytolysis of the myocardium which was unrelated to vascular distribution.

Aged↗

PubMed1996

Evaluation of perospirone (SM-9018), a novel serotonin-2 and dopamine-2 receptor antagonist, and other antipsychotics in the conditioned fear stress-induced freezing behavior model in rats.

We studied the effects of perospirone (SM-9018), a novel serotonin-2 (5-HT2) and dopamine-2 (D2) receptor antagonist (SDA), on conditioned fear stress (CFS)-induced freezing behavior in rats and compared its actions with those of other antipsychotics. Exposure of rats to the environment previously paired with foot shock induced marked freezing behavior, which was reduced by the anxiolytic diazepam (0.1-3 mg/kg, p.o.) or antidepressants, desipramine and imipramine (10-100 mg/kg, p.o.). Perospirone at 0.3-3 mg/kg, p.o. significantly attenuated the CFS-induced freezing behavior in a dose-dependent manner, while the effect was reduced at the higher dose of 6 mg/kg. Other SDA-type antipsychotics, clozapine (1-30 mg/kg, p.o.) and risperidone (0.03-1 mg/kg, p.o.), and selective 5-HT2 antagonists, ritanserin (0.1-1 mg/kg, p.o.) and ketanserin (0.3-1 mg/kg, p.o.), all reduced the freezing behavior with U-shaped dose-response curves. However, neither conventional antipsychotic, haloperidol (0.1-3 mg/kg, p.o.), chlorpromazine (3-100 mg/kg, p.o.), thioridazine (3-100 mg/kg, p.o.), mosapramine (3-100 mg/kg, p.o.) nor tiapride (30-1000 mg/kg, p.o.) reduced the CFS-induced freezing behavior. In addition, subacute treatment of rats with perospirone (1-10 mg/kg/day) or imipramine (30 mg/kg/day) for 2 weeks prevented the induction of the freezing behavior by CFS. These findings suggest that SDA-type antipsychotics including perospirone are effective for the treatment of mood disturbances such as anxiety and depressive mood associated with schizophrenia and have a broader efficacy profile as compared with the conventional antipsychotics.

Animals↗

PubMed1996

The effects of xylazine on intrauterine pressure, uterine blood flow, maternal and fetal cardiovascular and pulmonary function in pregnant goats.

To investigate the effects of xylazine on pregnant goats, xylazine induced changes in heart rate (HR), arterial blood pressure (ABP) and arterial blood pH and gases in the mother and fetus, as well as changes in intrauterine pressure (IUP) and uterine blood flow (UBF), were studied using a chronic preparation model of pregnant goats. Intramuscular administration of xylazine (0.2 mg/kg b.w.) caused a marked decrease in HR and ABP of the mother, which remained significantly reduced up to 120 min. In the fetus, a significant decrease in HR and a significant increase in ABP were recorded after only 5 min. Significant decreases of maternal arterial blood pH and oxygen partial pressure (Po2) were observed up to 120 and 30 min after the injection, respectively. Fetal arterial blood pH and Po2 also decreased, but these changes were milder and less persistent than those of the mother. Within 2 to 5 min after the administration of xylazine, IUP began to increase and remained high for about 15 min. Thereafter, there was a frequent periodic increase in IUP. After 5 min, UBF decreased significantly and remained low up to 120 min. A fall in UBF was associated with a rise in IUP. These findings suggested that administration of xylazine to pregnant goats results in a decrease in UBF arising from the induction of uterine contractions, a decrease in circulating blood volume, hypoxemia and acidosis in the mother.

Animals↗

PubMed1996

Effect of positive end-expiratory pressure on extravascular lung water and cardiopulmonary function in dogs with experimental severe hydrostatic pulmonary edema.

The effects of ventilation at positive end-expiratory pressure (PEEP) on extravascular lung water (EVLW) and cardiopulmonary function were studied in dogs with experimental severe hydrostatic pulmonary edema, which was generated by inflating a left atrial balloon and simultaneously injecting warm 5% glucose solution into the pulmonary artery. The EVLW was measured by the double indicator dilution method using heat and sodium ions. All the dogs were ventilated at zero end-expiratory pressure (ZEEP) until the EVLW had increased by 200-300% (maximal edema), when they were divided into two groups, one of which (n = 6) was ventilated at a PEEP of 10 cm H2O throughout the 4 hr study period (PEEP group) and the other (n = 6) was maintained at ZEEP during their survival period (ZEEP group). All the dogs in the PEEP group survived ventilation for 4 hr, whereas all those in the ZEEP group died within 3 hr, (2 within 1 hr, 1 between 1 and 2 hr and 3 between 2 and 3 hr). The EVLW of the PEEP group remained unchanged throughout the 4 hr study period, whereas that of the ZEEP group showed a tendency to increase. The arterial oxygen tension (PaO2) increased significantly throughout the 4 hr period of ventilation in the PEEP group but tended to decrease in the ZEEP group. In conclusion, PEEP improves gaseous exchange, but does not decrease the EVLW in dogs with experimental severe hydrostatic edema.

Analysis of Variance↗

PubMed1996

Maternal and fetal catecholamine responses to acute hypoxemia in Japanese Saanen goats.

Our purposes were to investigate the effects of acute hypoxemia on maternal and fetal physiological and biochemical responses in Japanese Saanen goat and to compare these responses to those obtained in other species in the previous studies. Five pregnant Japanese Saanen goats at about 120 days of gestation were operated to make fetal chronic preparation models. After a minimum of 4 days of postoperation, hypoxemia was induced by having the ewe breathe a hypoxic gas mixture (10% O2, 3% CO2, in N2) for 30 min. Maternal PO2 decreased from 84 to 40 mmHg, and fetal PO2 decreased from 22 to 16 mmHg. Only the fetal pH was significantly decreased by hypoxemia. Maternal heart rate increased with increases in arterial pressures. On the other hand, fetal heart rate showed bradycardia with a transient increase in blood pressure. During hypoxemia, maternal catecholamines minimally increased, while fetal plasma concentrations of epinephrine and norepinephrine were significantly increased. These changes in Japanese Saanen goats were first revealed by the current study and were compatible with the previous reports with sheep and monkeys. These observations suggest that the Japanese Saanen goats may be an adequate animal model for investigation of fetal physiology.

Animals↗

PubMed1996

Comparison of circulatory effects between arginine vasopressin (AVP) and dopamine in conscious newborn goats.

By using conscious chronically instrumented newborn goats, the circulatory effect of arginine vasopressin (AVP) (20 mIU/kg/ min) was studied, assuming a potential use for AVP to treat circulatory failure in the newborn, and the results were compared with those of dopamine (20 micrograms/kg/min). The AVP infusion decreased heart rate (HR) and cardiac output (CO) significantly, and increased systemic arterial pressure (SAP) and pulmonary arterial wedge pressure (PAWP) significantly, but did not change pulmonary arterial pressure (PAP) appreciably. The dopamine infusion did not change HR, SAP, and PAWP but increased CO and PAP significantly. Right atrial pressure (RAP) increased significantly in both groups. The pulmonary vascular resistance (PVR) increased significantly in both groups. The systemic vascular resistance (SVR) increased significantly in the AVP group, but did not change during experiments in the dopamine group. The calculated PVR/SVR ratios decreased significantly from the baseline value after initiation of the AVP infusion. In contrast, the dopamine infusion increased PVR/SVR ratios significantly throughout the experiments. Persistent pulmonary hypertension of the newborn (PPHN) is a syndrome characterized by right-to-left shunting of blood at the level of the foramen ovale and ductus arteriosus. AVP may reduce the shunting of blood by elevating only SAP selectively.

Animals↗

PubMed1996

Effects of antihypertensive drugs on maternal and fetal hemodynamics and uterine blood flow in pregnant goats--comparison of nicardipine and labetalol.

This study was designed to compare the effects of nicardipine (0.02 mg/kg) and labetalol (0.5 mg/kg) on the uterine blood flow and fetal circulation after intravenous administration in unanesthetized, chronically instrumented pregnant goats. Significant decreases in maternal blood pressure and uterine blood flow were observed in both groups. The maternal heart rate increased significantly after the injection of nicardipine, whereas this change was not observed after the labetalol injection. The fetal heart rate, blood pressure and acid-base status did not change after the injection of either nicardipine or labetalol. These observations in pregnant goats suggest that both nicardipine and labetalol might be useful drugs for the treatment of acutely hypertensive crises in pregnant patients.

Animals↗

PubMed1996

Radiographical evaluation of bone maturation in Japanese black beef cattle.

Epiphyseal ossification in the radius, ulna, metacarpus, proximal phalanx and tuber calcaneus was examined radiographically in Japanese Black beef cattle. The grade of standard ossification was assessed monthly for each epiphysis. Bone maturations could be divided into 8 grades for the distal radius and distal ulna, 7 grades for the distal metacarpus, 5 grades for the proximal phalanx, and 8 grades for the tuber calcaneus, respectively. The closure of the epiphyseal line completed at the earliest (12-14 months of age) on the proximal phalanx, and at the latest (35-37 months of age) on the distal ulna. Changes in gradings were steep at 0 to 5 months of age but became almost constant after 10 months of age in all the epiphyses. There were no significant differences in bone maturation between the cattle with different sex and breeding conditions.

Aging↗

PubMed1996

Effects of inhaled nitric oxide on hypoxic pulmonary vasoconstriction in dogs and a case report of venae cavae syndrome.

We investigated the effect of inhaled nitric oxide (NO) on hypoxic pulmonary vasoconstriction (HPV) in dogs, by treating a dog suffering from venae cavea syndrome (VCS) and pulmonary hypertension (PH) with NO inhalation. The increasing mean pulmonary arterial pressure (mPAP) induced by hypoxia was lessened significantly by NO inhalation. High PAP in VCS also declined as a result of NO inhalation. These results suggested that inhaled NO can reverse HPV in dogs and prevent worsening PH during surgical extraction of heartworm in VCS.

Administration, Inhalation↗

PubMed1996

Evaluation of pulmonary vasodilatory capacity with inhaled nitric oxide in a dog with patent ductus arteriosus.

A female Maltese dog with patent ductus arteriosus (PDA) showing left congestive heart failure and moderate pulmonary hypertension was evaluated for pulmonary vasodilatory capacity using low concentrations of inhaled nitric oxide (NO) in comparison with oxygen during preoperative cardiac catheterization. Increasing the inspired oxygen concentration (FiO2) to 1.0 without adding NO did not reduce the mean pulmonary arterial pressure (mPAP). However, inhalation of NO at FiO2 1.0 reduced mPAP rapidly without changing other hemodynamic and gas exchange parameters. From these results, inhaled NO caused selective pulmonary vasodilation without producing systemic vasodilation, which may provide a safe and effective mean of evaluating the pulmonary vasodilatory capacity of dogs with PDA.

Administration, Inhalation↗

PubMed1996

Tensile force of pacing lead extraction. A comparison between tined type and screw-in type.

Three months after implantation of endocardial pacing leads in 10 mongrel dogs, the tensile forces needed to remove 5 tined type and 5 screw-in type leads were compared experimentally. Mean maximum tensile force was 291 +/- 174 g with the screw-in type and 1174 +/- 369 g with the tined type (p < 0.01). Histopathologically, no changes suggesting any myocardial damage due to lead extraction were recognized in cases where screw-in type leads were used. These results support the clinical feasibility of safe and easy manual retraction of infected pacing leads of the screw-in type.

Animals↗

PubMed1996

Branching patterns in coronary artery and ischemic areas induced by coronary arterial occlusion in the CLAWN miniature pig.

This study of 28 CLAWN miniature pigs (male 17, female 11, mean weight 29 kg) was undertaken to investigate the coronary arterial branching patterns and the ischemic area induced by surgical occlusion of the left anterior descending artery (LAD) and change in the ischemic area over time. These results were compared with those in dogs, which have frequently been used in myocardial ischemic research. Regarding the coronary arterial branching pattern, there were fewer ventricular branches from the right and left coronary arteries than in dogs. The septal branches arose from only the LAD and the posterior descending artery (PD). The largest septal artery branched from the LAD. There were two types of septal artery branching patterns. In approximately 80% of the CLAWN miniature pigs, the PD arose from the right coronary artery (Right dominance). The peculiarity of the coronary arterial branching pattern in the CLAWN miniature pigs was more similar to human beings than to dogs. The ischemic area induced by occlusion at three-fifths distal section of the LAD was 12.1% to 22.6% (mean 17.1%) of the left ventricle. The ischemic area in all animals that died of global left ventricular malfunction and hemodynamic instability after LAD occlusion was more than 25% of the left ventricle.

Animals↗

PubMed1996

Relationship between arterial and end-tidal carbon dioxide pressure during controlled ventilation in porcine neonates.

To investigate the validity of ETCO2 in porcine neonates, which have been frequently used as an experimental model for human neonates, the relationship between arterial (PaCO2) and end-tidal PCO2 (ETCO2) in porcine neonates was examined under different respiratory conditions by regulating both inspiratory flow and positive end expiratory pressure (PEEP). The difference between PaCO2 and ETCO2 widened significantly, according to the significant decrease in tidal volume/body weight ratio (TV/BW) caused by the increase of PEEP. A lower correlation between PaCO2 and ETCO2 was observed in < 6 ml/kg than in > or = 6 ml/kg TV/BW. It therefore seems reasonable to conclude that, in porcine neonates, the valid ETCO2 measurements corresponding to PaCO2 would be obtained at > or = 6 ml/kg TV/BW.

Animals↗

PubMed1996

Smooth muscle cell proliferation in the arterial intima after stretch injury: relationship between the severity of stretching and intima hyperplasia in New Zealand white rabbits.

We examined histologically whether the severity of arterial stretch injury is related to the degree of subsequent intimal hyperplasia. In six male New Zealand White rabbits, the common carotid artery was hyperextended with a 3F Fogarty balloon catheter. Two weeks later, no proliferative change was evident in the intima in the most hyperextended portion. Paradoxically, however, intimal hyperplasia due to smooth muscle cell proliferation was observed in the moderately extended portions. The intimal hyperplasia appeared to be exacerbated where the arterial stretching was more severe. It is concluded that the severity of arterial stretch injury is closely related to the intimal proliferation of smooth muscle cells.

Animals↗

PubMed1996

Lack of inhibitory effect of dexamethasone on exhalation of nitric oxide by healthy humans.

Nitric oxide (NO) is present in the breath exhaled from healthy humans. The location and subtype of the NO synthase responsible for the expired NO are unknown. As dexamethasone inhibits the induction of NO synthase, we evaluated the effect of administering dexamethasone (4 mg/day for 2 days) on the amount of NO exhaled by eight healthy men. The amount of NO showed a significant linear correlation with the duration of exhalation, allowing the rate of NO release to be calculated. The rate of NO release was 0.047 +/- 0.023 nmol/s before drug administration. There was no significant change in the release rate at the end of the 2-day administration of drug or at 5 days after cessation. Serum concentrations of interferon-gamma and interleukin-1 beta were unaffected by the administration of dexamethasone. These results suggest that the NO released from the human airway under normal conditions is not generated by the action of inducible NO synthase.

Adult↗

PubMed1996

Non-traumatic arteriovenous fistulas of the scalp treated by a combination of embolization and surgical removal.

Three patients with non-traumatic arteriovenous fistulas (AVFs) of the scalp were treated by embolization using acrylate glue through the transarterial route or by direct puncture of the lesions and then surgical resection. Complete cure was achieved in all three patients. Selective angiography is indispensable in the correct diagnosis of scalp AVFs. Embolization facilitates surgical removal when necessary, and this combination is the treatment of choice for scalp AVFs.

Acrylates↗