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Biomedical subjects

N Hirata

Publications and source records attributed to N Hirata.

At least 91 records · Page 5Linked to original sources
PubMed1997

Surgical repair of pulmonary stenosis with intact ventricular septum in a 68-year-old woman.

Patients with mild pulmonary stenosis after infancy rarely have symptoms or develop increasing obstruction. We experienced a 68-year-old woman with severe pulmonary valvar and infundibular stenosis (peak to peak pressure gradient = 80 mmHg). She had been pointed out heart disease at the age of six. Endocarditis at the age of 17 might induce calcification of valve and affect the progression of pulmonary stenosis, and moreover, which might gradually develop severe subvalvar obstruction and poststenotic aneurysm of pulmonary trunk. She refused operative intervention because of mild clinical symptoms (NYHA class II), but we recommended surgical repair due to repeated transient ischemic attacks, which were suspected paradoxical embolism through persistent foramen ovale. She underwent pulmonary valvotomy and infundibular resection and is doing well.

Aged↗
PubMed1997

[Difference between the clinical significance of Credé voiding and Valsalva voiding in the urological management of spina bifida patients].

Retrospective analyses were performed to elucidate the clinical significance between Credé voiding (n = 56) and Valsalva voiding (n = 22) in the urological management of spina bifida patients who do not match the indication of clean intermittent catheterization. The age at initiating the urological management ranged from 0 to 31 years old (mean 2.1) in the Credé voiding and from 0 to 20 years old (mean 4.5) in the Valsalva voiding group. Seventeen patients in the Credé voiding group and 13 in the Valsalva voiding group were followed up for more than 10 years with a mean follow-up period of 14.6 and 13.7 years, respectively. Three patients in the Credé voiding group and one in the Valsalva voiding group showed progression of bladder deformity. In one patient in the latter group, vesicoureteral reflux newly appeared. In the Valsalva voiding group, disappearance or improvement of hydronephrosis was seen in three patients and that of hydroureter in three, bladder deformity in one, and vesicoureteral reflux in one. On the contrary, no patients in the Credé voiding group showed favorable changes in these pathological conditions except for disappearance of vesicoureteral reflux in one patient. Although these findings suggest possible superiority of Valsalva voiding over Credé voiding in the preservation of urinary tract, the differences between the two groups were not statistically significant. The clinical significance of Valsalva voiding remains to be elucidated through further study in neurogenic bladder patients.

Abdomen↗
PubMed1996

Urethral opening pressure in patients with myelodysplasia.

We evaluated 60 patients with myelodysplasia using the urethral opening pressure (UOP) which is defined as the total intravesical pressure at the moment when urine passes through the external sphincter by the Credé or the Valsalva maneuver. Twenty nine of the patients showed UOP value greater than 35 cmH2O and 31 below 35 cmH2O. In the high pressure group, patients showed a tendency to preserve sphincter activity and had mild paralysis of the lower extremities. In contrast, most of patients in the low pressure group showed an underactive sphincter and severe paralysis of the lower extremities. The incidence of deterioration of the upper urinary tract, vesicoureteral reflux (VUR) and bladder deformity were significantly high in the high pressure group than those in the low pressure group (75.9% vs 16.1%, 72.4% vs 22.6%, 82.8% vs 29.0%, respectively, P < 0.05). During the follow-up period (42 months on average), the voiding methods were changed in 15 patients from the Credé maneuver to clean intermittent catheterization, and total of 12 operations were performed (10 antiVUR operation and two with an ileocystoplasty). Finally, approximately 90% of the patients in both the high and the low pressure groups were evaluated as improved or stable in the upper urinary tract, VUR and bladder deformity after conservative or surgical managements. UOP is considered to be one of the useful parameters to select the high risk patient in the urological management of myelodysplastic patients.

Adolescent↗
PubMed1996

Inhibitory effect of tyrosine kinase inhibitors on antigen-induced tracheal contraction and histamine release in guinea pigs.

We examined the effect of two different types of tyrosine kinase inhibitor, herbimycin A and genistein, on antigen-induced tracheal contraction and antigen-induced histamine release from the trachea in sensitized guinea pigs in vitro. Herbimycin A (1-10 microM) and genistein (1-10 microM) significantly inhibited antigen-induced tracheal contraction, compared with control. Additionally, herbimycin A (1-10 microM) and genistein (3-10 microM) significantly inhibited antigen-induced histamine release from the trachea in a concentration-dependent manner, compared with control. On the contrary, herbimycin A and genistein did not suppress acetylcholine- and histamine-induced tracheal contraction. We concluded that herbimycin A and genistein inhibit antigen-induced tracheal contraction without inhibiting smooth muscle contractility, and these inhibitory effects are due to, at least partially, inhibiting histamine release from tracheal mast cells.

Acetylcholine↗
PubMed1995

Evidence that PGF2 alpha-induced contraction of isolated guinea pig bronchi is mediated in part by release of tachykinins.

To investigate whether prostaglandin F2 alpha (PGF2 alpha) stimulates the release of tachykinins and whether the tachykinins play a role in the PGF2 alpha-induced bronchial contraction, we examined the contractile response to PGF2 alpha in the presence or absence of a neutral endopeptidase (NEP) inhibitor phosphoramidon in the guinea pig main bronchus in vitro. Because NEP effectively cleaves tachykinins, we hypothesized that the inhibition of NEP would enhance a PGF2 alpha-induced bronchial contraction if PGF2 alpha stimulates the release of tachykinins. Phosphoramidon significantly enhanced the concentration-response curve to PGF2 alpha. And it also significantly enhanced 10(-5) M PGF2 alpha-induced contraction. The enhancement was significantly attenuated in tissues where the tachykinins had been depleted by treatment with capsaicin. Furthermore, the enhancement of contraction was also significantly attenuated in the presence of tachykinin antagonist FK-224 (10(-5) M). Tetrodotoxin, a sodium-channel blocker that blocks nerve conduction, did not affect the enhancement. From these results we conclude that 1) PGF2 alpha causes the release of tachykinin-like substances, 2) these substances play a role in bronchial contraction in tissues where NEP activity is inhibited, and 3) nerve conduction is not necessary for the release of these substances in the guinea pig bronchus.

Animals↗
PubMed1995

[Fine needle aspiration cytology in screening of prostatic cancer].

Between October 1990 and June 1993, 112 patients underwent fine needle aspiration cytology and core needle biopsy of the prostate under transrectal ultrasonographic guidance. They were suspected of having prostatic cancer from the prostatic antigen level, digital rectal examination and/or transrectal ultrasonography. Twenty seven of the 112 cases (24%) were diagnosed with prostatic cancer. Their cytological diagnoses showed 22 class IV or V, 2 class III, and 3 class I or II. Efficiency, false negative rate and false positive rate were 86%, 11% and 0% in fine needle aspiration cytology. We could obtain sufficient samples for fine needle aspiration cytology in all cases. No severe complication was observed. However, we missed 3 patients, in fine needle aspiration cytology, who were strongly suspected of having prostatic cancer, and reexamination or additional core needle biopsy would have been necessary on 15 of the 112 patients (13%) who showed false negative or class III cytological results, if we had screened prostatic cancer only by fine needle aspiration cytology. In conclusion, fine needle aspiration cytology may not be as useful as core needle biopsy to screen prostatic cancer.

Adenocarcinoma↗
PubMed1995

[Evaluation of sexual function in adults with myelomeningocele].

In the present study, sexual function in 46 patients (22 males and 24 females) with myelomeningocele was assessed by a questionnaire study. The mean age of the patients was 24.0 +/- 9.6 years (with an age range of 18 to 50) for male patients and 25.2 +/- 6.2 years (with an age range of 18 to 42) for female patients. Having interest in the opposite sex and sexual desire were evident in 95% and 100% of male patients, and 83% and 75% of female patients, respectively. In male patients, erection was achieved in 95% by visual stimulation and in 86% by tactile stimulation. However, only 27% of the patients with erectility were satisfied with penile rigidity. Ejaculation and orgasm was noted in 67%. Orgasm was frequently seen in patients whose external sphincter activity was maintained. The age and the degree of lower extremity paralysis according to Sharrard classification were not significantly correlated with sexual function. In female patients, menstruation was regular in 95%, vaginal secrete was adequate in 88%, but only 19% of the patients felt ecstacy around perineal lesion at coital movements. In female patients, sexual function was not correlated with the age, the degree of lower extremity paralysis and detrusor activity-sphincter activity. Although most patients had sexual desire, only 18% of the males, and 33% of the females, had sexual intercourse activities. It appears, therefore, that these patients need to be given appropriate advice.

Adolescent↗
PubMed1994

Response of right ventricular systolic function to exercise stress: effects of pulmonary vascular resistance on right ventricular systolic function.

To elucidate factors influencing responses of right ventricular systolic function to exercise stress, we evaluated the right ventricular ejection fraction and peak ejection rate with two different loading conditions, atrial septal defect and mitral stenosis, at rest and during exercise by means of gated equilibrium blood pool radionuclide ventriculography. In both atrial septal defect and mitral stenosis, strong correlations between changes in the right ventricular ejection fraction with exercise and pulmonary vascular resistance at rest (r = -0.97, p < 0.001; r = -0.86, p < 0.005: respectively) were found. Significant correlations between changes in the right ventricular peak ejection rate with exercise and pulmonary vascular resistance at rest (r = -0.85, p < 0.05; r = -0.75, p < 0.01: respectively) were found in atrial septal defect and mitral stenosis. Both the right ventricular ejection fraction and peak ejection rate were lower during exercise than at rest when pulmonary vascular resistance at rest was more than 200 dynes.sec.cm-5.m2 in both atrial septal defect and mitral stenosis. In conclusion, right ventricular systolic function responding to exercise stress was influenced by the pulmonary vascular resistance in both atrial septal defect and mitral stenosis.

Adult↗
PubMed1994

Synthetic studies of sesquiterpenes with a cis-fused decalin system, 5. A synthetic approach to the study of structure-activity relationships of the termiticidal norsesquiterpenoids, chamaecynone and related compounds.

Various analogues of chamaecynone [1] were prepared from alpha-santonin, and the termiticidal activity of these compounds was examined. All compounds possessing a 5 beta H-13-noreudesmane skeleton with a ethynyl group at C-7 showed significant termiticidal activity. Changes in the structure of the A-ring of these compounds also influenced the potency of their termiticidal activity.

Animals↗
PubMed1994

Alendronate modulates osteogenesis of human osteoblastic cells in vitro.

The bisphosphonates, which are carbon-substituted pyrophosphates, have been studied extensively both in vivo and in vitro to elucidate their effects on bone tissues and cells. However, because these agents were shown to have a potent inhibitory effect on bone resorption, the majority of studies have focused on only this aspect of bone metabolism. There appears to be less information regarding the direct effect of bisphosphonates on bone formation, so thus we undertook experiments to investigate the effects of bisphosphonates, especially alendronate, on the mineralization and matrix protein synthesis of human osteoblastic cells in vitro. The data show that the bisphosphonates, alendronate, etidronate and pamidronate, suppressed 1,25-dihydroxycholecalciferol (1,25(OH)2D3)-stimulated mineralization of human osteoblastic cells at high concentrations, while relatively lower concentrations of alendronate and etidronate potentiated mineralization of the cells in the presence of 1,25(OH)2D3. The potentiation of mineralization with alendronate was accompanied by increased synthesis of bone matrix proteins, osteocalcin and collagen, and the mRNA of pro alpha(I) collagen. These findings show that in addition to their well-known effects on bone resorption, bisphosphonates have significant and direct effects on osteogenesis in osteoblasts in vitro. The actual mechanism remains to be further investigated.

Alendronate↗
PubMed1994

Crossed and uncrossed segmental synaptic effects on obliquus externus abdominis motoneurons from cutaneous and cutaneous-muscle nerve in spinal cats and alpha-chloralose-anesthetized cats.

Segmental synaptic responses in the obliquus externus abdominis (OEA) for stimulation of the dorsal cutaneous and cutaneous-muscle (CD) nerve and the ventral cutaneous and cutaneous-muscle (CV) nerve were investigated in 49 spinal cats and 28 cats under alpha-chloralose anesthesia (chloralose cats) with an intracellular recording method. The result that there was no monosynaptic PSP in OEA motoneurons for stimulation of the CD or CV nerves (containing the cutaneous-muscle nerve) indicates that the cutaneous muscle of the dorsal or ventral area does not connect monosynaptically to the OEA motoneuron. The OEA motoneurons in chloralose cats received few effects from descending pathways coming from the upper spinal cord and the brain. Almost all OEA neurons had polysynaptic EPSP responses for stimulation of the ipsilateral or contralateral CD or CV nerves at 5-10T stimulus intensity in spinal or chloralose cats, which indicates that the OEA muscle can contract bilaterally when strong impulses of superficial afferents from the left or right skin or cutaneous muscle enter in the spinal cord.

Anesthesia, General↗
PubMed1994

Evaluation of regional myocardial perfusion in areas of old myocardial infarction after revascularization by means of intraoperative myocardial contrast echocardiography.

Because myocardial revascularization to areas of old myocardial infarction brings about functional recovery to some extent to myocytes in those areas, the assessment of regional myocardial perfusion on those areas after myocardial revascularization may allow myocardial viability to be estimated. Using intraoperative myocardial contrast echocardiography by direct injection of 2 ml sonicated 5% human albumin into saphenous vein grafts, we assessed regional myocardial perfusion in 16 revascularized areas of old myocardial infarction. We estimated the myocardial viability of areas with respect to myocardial perfusion, and we compared these results to both the improvement of regional wall motion after myocardial revascularization (increase in segmental wall thickening during systole) and relative thallium 201 activity obtained by quantitative analysis of preoperative exercise myocardial thallium 201 distribution on delayed images. The background-subtracted peak peak intensity of myocardial enhancement and the ratio of endocardial to epicardial intensity were determined in each revascularized area. An inverse correlation existed between peak intensity (18 +/- 7) and the endocardial/epicardial ratio (0.88 +/- 0.17) (r = -0.63, p < 0.01). A good correlation was found between peak intensity and both the percent increase in segmental wall thickening (r = 0.73, p < 0.005) and the relative thallium 201 activity (r = 0.81, p < 0.005). These results suggested that regional myocardial perfusion after myocardial revascularization in areas of old myocardial infarction distributed better to the epicardial halves than to the endocardial halves, and that the peak intensity could be related to myocardial viability.

Aged↗
PubMed1993

Long-term appraisal of coronary bypass operations in familial hypercholesterolemia.

Long-term results of coronary artery bypass grafting (CABG) in consecutive 32 patients with familial hypercholesterolemia, 6 homozygotes and 26 heterozygotes between 1976 and 1990, were analyzed. Seventeen patients in the early series underwent CABG with vein grafts alone. Subsequently, 15 patients underwent CABG with internal mammary artery grafting to the left anterior descending artery and received intensive lipid-lowering treatments early after CABG. All homozygotes and 1 heterozygote received intermittent low-density lipoprotein apheresis after CABG. There was only one late noncardiac death (3%), and the actuarial rates of freedom from cardiac events (myocardial infarction, cardiac death, and angina pectoris) were 60% at 5 and 10 years for homozygotes, and 87% and 73% for heterozygotes. The cardiac event-free curve for the heterozygous familial hypercholesterolemia group was comparable with that for the random age-matched subset of patients without familial hypercholesterolemia who underwent CABG during the same period. Two of 3 homozygotes and 4 of 14 heterozygotes in the early series had one or more cardiac events, whereas no patients in the late period had cardiac events. The patency rate of internal mammary artery grafts to the left anterior descending artery from 1 to 3 years after CABG was significantly higher than that of vein grafts to the left anterior descending artery (92 versus 45%; p < 0.05). Abdominal aortic aneurysm developed postoperatively in 2 homozygotes and 2 heterozygotes without sufficient cholesterol reduction. In conclusion, internal mammary artery grafting in combination with postoperative intensive lipid-lowering treatments, including low-density lipoprotein apheresis, may provide acceptably good long-term results of coronary revascularization in patients with FH.

Actuarial Analysis↗
PubMed1993

Renal hypouricemia due to enhanced tubular secretion of urate associated with urolithiasis: successful treatment of urolithiasis by alkalization of urine K+, Na(+)-citrate.

We encountered a case of hypouricemia with increases both in urate clearance (Cur) and in the ratio of Cur to creatinine clearance (Cur/Ccr), the normal daily urinary excretion of urate, and urolithiasis. Pyrazinamide markedly decreased Cur and Cur/Ccr, and both probenecid and benzbromarone markedly increased Cur and Cur/Ccr, however, benzbromarone did not increase either Cur or Cur/Ccr under pretreatment with pyrazinamide in the patient. Thus, the diagnosis was made of renal hypouricemia due to enhanced tubular secretion of urate. The urinary pH of the patient tended to be acidic. Three months after the start of alkalization of the patient's urine by K+, Na(+)-citrate, both urolithiasis and the symptoms related to urolithiasis disappeared. These results suggest that renal hypouricemia due to enhanced tubular secretion of urate can result in urolithiasis and the alkalization of urine may be an effective treatment for uric acid stones.

Benzbromarone↗
PubMed1993

Colonic submucosal tumors: a new classification based on radiologic characteristics.

OBJECTIVE: Despite advances in gastrointestinal radiologic techniques, findings from barium enema studies cannot be used reliably to predict the histologic nature of a colonic submucosal tumor. Therefore, we generated a new and comprehensive classification system for all colonic submucosal tumors based on a correlation between their radiologic characteristics and their histopathologic features. MATERIALS AND METHODS: Between 1978 and 1990, 89 patients had 95 colonic submucosal tumors diagnosed on the basis of barium enema studies and confirmed by biopsy or surgery. Of these, 39 patients (44%) were symptomatic and 50 patients (56%) were asymptomatic. Single lesions (82 cases) and multiple lesions (12 cases of lymphoma and one case of blue rubber bleb nevus) were observed. The 95 lesions included 21 carcinoids, 27 malignant lymphomas, 17 lipomas, 10 lymphangiomas, six leiomyosarcomas, five leiomyomas, and nine others. We analyzed the radiologic findings and classified these lesions according to their appearance. RESULTS: All tumors were classified on the basis of their morphologic appearance into five types: (1) wide-based sessile lesion with gradually sloping margin and smooth surface (17 cases); (2) wide-based sessile lesion, more polypoid than the first type, with a smooth surface, with or without a central depression (49 cases); (3) wide-based sessile lesion with lobulated surface (six cases); (4) pedunculated lesion with smooth or granular surface (17 cases); (5) unclassified, not any of the previously mentioned types, may be diffusely stenotic or aneurysmal (six cases). The most common finding was the wide-based sessile lesion with a smooth surface and a possible central depression; next most common was the wide-based sessile lesion with gradually sloping margin and smooth surface; next was the pedunculated lesion with a smooth or granular surface. Eighty-six percent of the lesions were single; 14% were multiple. Histologic confirmation revealed mainly lymphoma (29%) and carcinoid (22%), of which the most common finding was a wide-based sessile lesion with a smooth surface, with or without a central depression. CONCLUSION: This new classification based on radiologic characteristics covers all varieties of colonic submucosal tumors. It can serve as a guideline for predicting a specific diagnosis of a colonic submucosal tumor on the basis of radiologic findings.

Adolescent↗