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Biomedical subjects

M Okamoto

Publications and source records attributed to M Okamoto.

At least 523 records · Page 29Linked to original sources
PubMed1995

Effects of heart rate on left atrial contractile performance and left ventricular filling during atrial systole in dogs.

Left ventricular (LV) diastolic filling and left atrial (LA) contribution have been investigated in patients with heart disease. However, many of these studies were not conducted at a constant heart rate, and the effects of heart rate remain unclear. The purpose of this study was to clarify the effects of the heart rate on left atrial contractile performance and left ventricular filling during atrial systole. The changes in LA and LV dimensions and pulmonary venous (PV) flow were determined in 9 open-chest dogs by a sonomicrometer and an electromagnetic flowmeter. With a stepwise decrease in the pacing rate from 110 beats/minute to 70 beats/minute, the LA dimension just before atrial contraction increased from 21.4 +/- 0.6 mm to 23.1 +/- 0.7 mm (p < 0.01), and the LA systolic shortening increased from 1.6 +/- 0.1 mm to 2.1 +/- 0.1 mm (p < 0.01). However, the calculated LV filling volume during atrial systole decreased from 1.9 +/- 0.3 ml to 1.4 +/- 0.2 ml (p < 0.01). The PV flow during atrial systole was directed toward the LA, and the LA influx volume from PV decreased from 0.6 +/- 0.1 ml to 0.2 +/- 0.04 ml (p < 0.01). With a decrease in the pacing rate, the LA Frank-Starling mechanism operated. However, LV filling during atrial systole decreased because of the decrease in PV flow to the LV via the LA. Thus, LA contractile performance cannot always be evaluated from LV filling.

Animals↗
PubMed1995

[Invention of a forced-air-ventilated micro-isolation cage and rack system--environment within cages: temperature and ammonia concentration].

There is little information about microenvironments within laboratory animal cages, although several guidelines on the macroenvironment in laboratory animal rooms have been reported. We have developed a forced-air ventilation system (FVMIS) to improve laboratory animal well-being. In this study, we tested the performance of the FVMIS in terms of temperature and ammonia concentration within cages. Continuous measurement of temperature and ammonia concentration was carried out in FVMIS cages housing 5 rats each. The average temperature within the cages was 22 degrees C to 24 degrees C, and the temperature difference among cages was 0.93 degrees C. The air exchange rate used was 65 changes per hour. FVMIS was capable of controlling the temperature within cages uniformly and accurately with a lower air exchange rate than with the conventional system. The ammonia concentration reached 20 ppm within 9 days in a filtercapped conventional cage, but took 13 to 16 days to reach 20 ppm with FVMIS. It appears that FVMIS is capable of suppressing the ammonia concentration increase in cages, thereby reducing the frequency of cage changes and the stress to laboratory animals when cages are changed. In the present study, it was confirmed that FVMIS contributes not only to microenvironmental control in terms of temperature and ammonia concentration with a lower air exchange rate, but also to animal well-being.

Ammonia↗
PubMed1995

[Changes in hearing features according to days from onset of sudden deafness].

We analyzed 746 patients with idiopathic sudden hearing loss who visited our clinic within 16 days after the onset. Patients were divided into 10 groups according to the number of days between the initial visit and the onset. Initial hearing levels, audiometric types and hearing recoveries were investigated in these groups to estimate the natural history of sudden deafness. The results were as follows: 1) There were no significant differences among the 10 groups regarding the averaged five-frequency hearing levels of initial audiograms. 2) Regarding the audiometric types of the initial audiograms, flat and upward slope types were frequently seen in the groups who visited us within 6 days. In contrast, the population of down slope types gradually increased in the groups presenting after 7 days. In the ultimate audiograms, flat and down slope types were frequently seen in all groups. 3) There were significant differences among the 10 groups regarding the averaged five-frequency improvement (one-way analysis of variance, p < 0.01). After 9 days, hearing recovery became less likely.

Hearing↗
PubMed1995

[Management of hypopharyngeal and cervical esophageal cancer (HCEC): a comparative study of primary-surgical and primary-radiotherapeutic regimens].

The results of two treatment regimens for HCEC were compared. Surgery played a main role in the first regimen (Group A), in which patients underwent total pharyngo-laryngo-esophagectomy (with bilateral neck dissection and primary reconstruction by pectoralis major myocutaneous flap or gastric tube) after receiving 20 Gy of irradiation therapy. Chemotherapy was combined in some patients. In the second regimen (Group B), radiation was employed as the main treatment in order to conserve the larynx. Chemotherapy (UFT 300 to 600 mg/day; in some patients one or two courses of intra-venous cisplatinum therapy) was combined with radiation therapy (60 Gy) to improve the effectiveness of this regimen. In case of radiation failure, a salvage operation was performed. We investigated 60 HCEC patients who visited the Kitasato University Hospital during the period from 1983 to 1992. The tumor was located in the PC, PS, PW, and Ce areas in 3, 48, 5, and 4 patients, respectively. There were 25 cases in group A and 35 in group B. Five-year cumulative survival rates were 52% and 55%, respectively. In group B, tumor remained or recurred after the initial treatment in 13 patients. Three patients refused to receive salvage operation. Four of the 10 patients who received salvage operation became tumor free. The larynx preservation rate was 71% in group B. From the standpoint of improving QOL, the group B regimen is recommended.

Adult↗
PubMed1995

[Clinicopathological study of incidental renal cell carcinoma].

BACKGROUND: The objective of this study is to evaluate the clinicopathological features of incidental renal cell carcinoma, compared with non-incidental carcinoma. METHODS: Between July 1st, 1984 and June 30, 1994, 87 renal cell carcinoma patients were treated at our hospital; 56 had non-incidental renal cell carcinoma and 31 had incidental carcinoma. The clinicopathological features were examined. RESULTS: The incidence of incidental cancer ranges from 0 to 66%, and the incidence has increased in recent years. The median value of maximal tumor size was 4.0cm (1.5 approximately 8.0cm) for incidental cancer, and 8.0cm (3.0 approximately 16cm) for incidental cancer, and 8.0cm (3.0 approximately 16cm) for non-incidental cancer, i.e., the incidental cancer was significantly smaller than the non-incidental one (p < 0.001). The pathological stage of the resected non-incidental renal cell carcinoma (n = 47) was pT1, pT2, pT3 and pT4 in 0, 23, 21 and 3 patients, respectively. For the resected incidental renal cell carcinoma (n = 31) 3, 26, 2 and 0 patients showed pathological stages pT1, pT2, pT3 and pT4, respectively; the pathological stage of incidental renal cell carcinoma was significantly lower than that of non-incidental carcinoma (p < 0.001). Eighteen and 29 resected non-incidental renal cell carcinoma were grades 1 and 2, respectively, whereas 17 and 14 resected incidental renal cell carcinomas were in grades 1 and 2, respectively. Vascular invasion by tumor cells was shown in 31 (66.0%) and 8 (25.8%) patients with non-incidental and incidental renal cell carcinomas, respectively; the incidence of vascular invasion in incidental cancer being significantly lower than in non-incidental cancer (p < 0.001). The performance status and general condition in patients with incidental renal cell carcinoma were superior to those in patients with the non-incidental cancer. The 1, 3 and 5-year survival rate of all 87 renal cell carcinoma patients was 81, 62 and 57%, respectively. These rates for patients with non-incidental renal cell carcinoma were 72, 48 and 41%, respectively, and those for incidental cancer patients were 100%. The survival of patients with incidental renal cell carcinoma was significantly better than that of non-incidental carcinoma patients (p < 0.005). CONCLUSION: Our results suggest that the detection of incidental renal cell carcinoma will increase, and that the prognosis for renal cell carcinoma will improve. However, even in incidental renal cell carcinoma, careful long-term follow up may be necessary, since some tumors are comparatively large and exhibit vascular invasion.

Adult↗
PubMed1995

[Quality control of fine needle aspiration cytology of breast lesions].

From 1988 to 1993 we treated 1,310 cases of fine needle aspiration cytology of breast lesions. The results were positive for malignancy in 218, suspicious in 134, negative in 857, and inadequate specimen in 101. Histological examinations were performed in 461 cases; 243 malignancies and 218 benign lesions. The cytological diagnosis of these cases was positive in 211, suspicious in 91, negative in 142 and inadequate specimen in 17. The cytologic diagnosis of the cases of histological malignancy was positive in 198, suspicious in 24, negative in 17 and inadequate specimen in 4. Therefore we have 17 false negative cases. The histological diagnoses in these cases were scirrhous carcinoma (7), papillotubular carcinoma (6), invasive lobular carcinoma (2), mucinous carcinoma (1) and angiosarcoma (1). There were 13 cases of cytologically false positive cases; the histological diagnoses were fibroadenoma (4), mastopathy (4), papilloma (3), adenosis (1) and xanthogranuloma (1). For over six years, we have used a computer system incorporating both cytologic and histologic records. This system is very useful in quickly review the correlations of cytologic-histologic diagnoses. In addition to this system, a close relationship between clinical to pathological department is necessary in the quality control of diagnostic cytology.

Biopsy, Needle↗
PubMed1995

In situ proliferating status of mononuclear cells in rat small bowel grafts.

Rat small bowel transplantation was performed in three groups: syngeneic graft, Lewis to Lewis; allogeneic graft, Brown Norway to Lewis; and allogeneic graft with the immunosuppressant FK506 (1 mg/kg). Standard histology and bromodeoxyuridine (BrdU) labelling immunohistochemistry were applied to evaluate the in situ spontaneous proliferating status of the mononuclear cells in the graft lymphoid tissue. In untreated allograft, BrdU-labelling index (BLI) in lamina propria lymphocytes increased significantly on the 5th post-operative day (POD), when no sign of rejection was detected in the villous architecture, compared with isograft (11.8 +/- 2.0% vs 1.9 +/- 0.5%, P < 0.05). Changes in the BLI of lamina propria lymphocyte were also detected on the 3rd and 7th POD, although there were statistically less significant than on the 5th POD. In intraepithelial lymphocytes the changes in BLI were more probably caused by ischaemic damage than immunological reaction. In Peyer's patches and mesenteric lymph nodes, elevation of BLI was specific to rejection like that seen in lamina propria lymphocytes. By administration of FK506, both the elevation of BLI and the histopathological changes were suppressed successfully except for a transient elevation of BLI in Peyer's patches and mesenteric lymph nodes on the 3rd POD.

Animals↗
PubMed1995

[Proliferative cystitis forming tumorous lesion: a case report].

A 66-year-old woman was admitted with asymptomatic macrohematuria. Cystoscopy revealed bladder tumor with a diameter of about 1.5 cm and smooth surface. Transurethral resection was performed and histological examination showed proliferative cystitis, mainly consisting of cystitis glandularis. Proliferative cystitis is not so rare, but tumorous formation of it seems to be unusual.

Aged↗
PubMed1995

[Pharmacokinetics of SK & F 104864 in experimental animals. I. Plasma level].

A camptothecin derivative, SK & F 104864 (topotecan), was injected for 30 minutes into the rabbit ear vein at a dose of 2 mg/kg or 5 mg/kg, and the plasma concentration was assayed by a HPLC method. The plasma level of SK & F 104864 (lactone form) decreased bi-exponentially with mean alpha and beta half-lives of 0.101 h and 0.849 h at 2 mg/kg, respectively, and 0.518 h and 7.57 h at 5 mg/kg, respectively. The AUCs were 0.846 micrograms.h/ml at 2 mg/kg and 2.14 micrograms.h/ml at 5 mg/kg. The plasma level of total topotecan (SK & F 104864 plus SK & F 105992) decreased bi-exponentially with mean alpha and beta half-lives of 0.696 h and 9.07 h at 2 mg/kg, respectively, and 0.795 h and 8.97 h at 5 mg/kg, respectively. The AUCs were 2.15 micrograms.h/ml at 2 mg/kg and 5.73 micrograms.h/ml at 5 mg/kg. The AUCs of lactone form were 39.3% of total topotecan at the 2 mg/kg dose and 37.3% at the 5 mg/kg dose, respectively. After intravenous bolus injection of SK & F 104864 at 20 mg/kg into Sarcoma 180 bearing mice, the alpha and beta half-lives of SK & F 104864 were 0.401 h and 3.99 h, respectively, and the AUC was 5.49 micrograms.hr/ml. The alpha and beta half-lives of total topotecan were 0.517 h and 4.27 h, respectively, and the AUC was 9.88 micrograms.hr/ml. The ratio of lactone form to total topotecan was 55.6%.

Animals↗
PubMed1995

[Pharmacokinetics of SK & F 104864 in experimental animals. II. Tissue distribution].

After intravenous bolus injection of a camptothecin derivative, SK & F 104864 (topotecan), at 20 mg/kg into Sarcoma 180 bearing mice, the tissue concentration of total topotecan (SK & F 104864 plus SK & F 105992) in the mice decreased bi-exponentially, and the beta half-lives in most tissues were longer than those in plasma. The AUCs of total topotecan were extremely large in the kidney, that was followed by the pancreas > intestine > stomach > spleen > liver > thymus > lung > tumor > uterus > plasma. The concentration of total topotecan after 24 hours decreased to less than 2% of the peak level in most tissues except the kidney.

Animals↗
PubMed1995

[Atrial late potential (ALP) by P wave-triggered signal-averaged electrocardiogram].

Late potentials, possibly representing fractionated electrograms recorded directly from slowly conducting cardiac tissue, can be detected by signal averaged ECG (SAECG) from the body surface noninvasively. Ventricular late potential, recorded with SAECG, is a good predictor of ventricular tachyarrhythmias. Analogously, SAECG triggered by P wave has recently been proposed determining atrial late potential (ALP), possibly related paroxysmal atrial fibrillation. ALP is analyzed by the time domain or frequency domain method. In the former, the prolongation of filtered P duration is an index of ALP. The results obtained by FFT analysis in the latter are controversial, and thus additional study will be required to confirm their meaning and significance.

Atrial Fibrillation↗
PubMed1995

[Atrial late potential by P wave-triggered signal-averaged electrocardiogram and paroxysmal atrial fibrillation].

Atrial fibrillation (AF), which is rather a common disease has a high risk of developing systemic embolism and stroke. Accordingly it can be significant for us to predict a patient at risk for AF during sinus rhythm Recently signal averaged ECG triggered by P wave has been expected to detect atrial late potential (ALP), which is thought to coincide with fractionated ECG significantly recorded directly from atrial muscle of a patient with paroxysmal AF. Although many time-domain ALP indices have been proposed, those excepting filtered P duration remain controversial with their diagnostic criteria having not yet been established, many studies agree as to the prolongation of filtered P duration, as observed for patients with AF. Although, also recently, frequency domain method has been applied to ALP for FFT analysis with the view of detecting ALP possibly undetectable by time domain method, no results better than the above method have been obtained, and further examination is hoped for.

Atrial Fibrillation↗
PubMed1995

[The development of serum alkaline phosphatase and gamma-glutamyl transpeptidase in early stages of primary biliary cirrhosis].

We carried out a retrospective study for the development of biochemical abnormalities in nine patients with early stages of primary biliary cirrhosis (PBC). All patients had elevated serum alkaline phosphatase (ALP) and gamma-glutamyl transpeptidase (gamma-GTP) levels when the diagnosis of PBC was obtained. In all cases, serum gamma-GTP levels initially increased, followed by the elevation of ALP. In the routine laboratory tests gamma-GTP is more sensitive than ALP for the screening for early PBC.

Aged↗
PubMed1995

[Treatment of middle and lower ureteral stones with ESWL: evaluation of the results of 190 solitary stones in comparison with those of upper ureteral stones].

We analyzed the results of treatment with extracorporeal shock wave lithotripsy (ESWL) (Dornier HM-3) for middle and lower ureteral solitary stones from April 1986 to March 1993 in our hospital. A total of 238 sessions of ESWL were done for 71 cases of middle ureteral stones and 119 cases of lower ureteral stones. The findings were compared with those obtained on the upper ureteral solitary stones. The final stone-free rate of the upper ureteral stones by ESWL alone were 91.9%, whereas those of middle and lower ureteral stones were 86.2% and 85.2%. We conclude that ESWL is equally useful for middle and lower ureteral stones to upper ureteral stones.

Adult↗
PubMed1995

Morphological studies on the kidney of the spontaneous nephrotic (ICGN) mice in the late stage.

Spontaneous nephrotic (ICGN) mice develop proteinuria, hypoproteinemia and hypercholesterolemia. These symptoms steadily progress to chronic renal failure. Details of the changes of the kidney, in the late stage (more than 5 months old) were investigated by both light and electron microscopy. The kidney exhibited a slightly whitish, granular surface and the cortex became thinner and contained fibrous lesions, in which clusters of unaffected and occluded renal tubules were randomly scattered. In the juxtamedullary and outer medullary zone, there were highly dilated renal tubules, which sometimes contained urinary casts. The glomerulus exhibited basement membrane thickening in the capillary loops and the capillary lumen was narrowed in size and sometimes occluded. No detachment of the podocyte from the basement membrane was observed and the podocyte foot-processes were extensively fused, causing their characteristic slits to be lost. The thickened basement membranes were found both in the glomerulus and around the occluded renal tubules, while the basement membrane in the dilated renal tubule appeared normal. Therefore, the basement membranes of the glomerulus and renal tubules appear to react differently in the pathogenesis of the condition. In conclusion, ICGN mice are a good model for not only the nephrotic syndrome but also for chronic renal failure.

Animals↗
PubMed1995

[Long-term selective beta 1-blockade therapy for a patient with anthracycline-induced cardiomyopathy].

A 44 year-old woman with acute myeloid leukemia (AML, FAB, M4E) developed heart failure during treatment with anthracyclines for AML. She had not experienced heart disease and her left ventricular ejection fraction (LVEF) was 59% at the end of a successful remission induction therapy. Because her LVEF decreased to 33% after early consolidation therapy, the chemotherapy for AML was discontinued. The cumulative dose of daunorubicin, aclarubicin and mitoxantrone was 486 mg/m2, 135 mg/m2 and 55 mg/m2, respectively. In October 1990, four months after the end of the chemotherapy, heart failure (class III, NYHA) developed and did not improve by treatment consisting of dobutamin, digoxin and diuretics. Anthracycline cardiomyopathy was histologically confirmed by endomyocardial biopsy. Then we administered selective beta 1-antagonist, metoprolol (Seloken), with an initial dose of 5 mg/day which was doubled 3 times every 4 or 8 weeks to 40 mg/day, according to the treatment schedule of dilated cardiomyopathy. She recuperated satisfactorily (Class I, NYHA), and was discharged on February '91. Her LVEF gradually improved and it has been maintained at above 50% on an outpatient basis. The patient has been in complete hematological remission during this period. It seems that low dose selective beta 1-antagonist therapy has a potential to improve myocardial function in some patients with anthracycline cardiomyopathy.

Aclarubicin↗
PubMed1995

[A case of food-dependent exercise-induced anaphylaxis induced by shrimp].

The clinical study and in vitro study used with leukocytes were made of a case of food-dependent exercise-induced anaphylaxis induced by shrimp. A 26-year-old man experienced anaphylactic reaction of nasal obstruction, face edema and dyspnea while running 90 minutes after eating shrimp. He experienced similar episodes two years ago in his past history. IgE-RAST was positive for shrimp. Anaphylactic reaction and elevation of plasma histamine levels were verified by exercise challenge test after eating 100 g shrimp. At the same time, we verified the dedine of plasma cAMP levels after eating shrimp. In leukocyte stimulating test used with shrimp antigen, histamine level elevations, which were lower compared with calcium ionophore A23187 (Ca I 10(-6) M) stimulation, were recognized in dose dependent manner in this patient. But in normal subject, histamine level elevations were not recognized. We diagnosed him food-dependent exercise-induced anaphylaxis. It was suggested that there was relation between histamine release and decline of cAMP levels of plasma after eating shrimp in this case.

Adult↗