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Biomedical subjects

M Hamada

Publications and source records attributed to M Hamada.

At least 271 records · Page 15Linked to original sources
PubMed1995

Conservative treatment of isolated injuries to the posterior cruciate ligament in athletes.

We assessed arthroscopically 22 young athletes with an isolated acute posterior cruciate ligament (PCL) injury. Four had significant damage to the articular cartilage of the medial femorotibial compartment and were advised not to resume sports. Three underwent PCL reconstruction because of a reparable meniscal tear or instability. The other 15 were treated conservatively and resumed sport. At an average follow-up of 51 months, one had developed arthritic symptoms due to newly-developed severe chondral damage to the medial femoral condyle, but none of the other 14 had developed arthritic symptoms and most remained athletically active. Severe chondral damage should be seen at an early arthroscopy. Knees with an isolated injury to the PCL with concomitant articular damage may be successfully managed by conservative treatment.

Activities of Daily Living↗
PubMed1995

Salvage chemotherapy for recurrent Ewing's sarcomas.

Metastatic disease tends to recur after remission of Ewing's sarcoma. The effectiveness of ifosfamide in patients with recurrent Ewing's sarcoma was reported in recent years. We administered IFOS combined with etoposide, pirarubicin, and cyclophosphamide to 4 Ewing's sarcoma patients with metastatic disease, and succeeded in inducing second remissions in all cases.

Adolescent↗
PubMed1995

Clinical evidence for an association between left ventricular geometric adaptation and extracardiac target organ damage in essential hypertension.

OBJECTIVES: To elucidate an association between left ventricular geometric adaptation to sustained hypertension and preclinical extracardiac target organ damage in essential hypertension. We also studied the clinical significance of neurohumoral factors for cardiovascular structural changes. DESIGN: One hundred and forty patients with essential hypertension were divided into four subgroups, based on left ventricular mass index and relative wall thickness. With respect to extracardiac target organ damage, we measured the funduscopic grade of retinal changes and serum creatinine levels. RESULTS: Among the hypertensive patients, only 19 (14%) had a typical concentric hypertrophy (increase in left ventricular mass index and relative wall thickness). Hypertensive patients with concentric hypertrophy had the most advanced funduscopic abnormalities and the greatest renal involvement, and hypertensive patients without left ventricular hypertrophy had the least extracardiac target organ damage. Plasma renin activity and plasma aldosterone concentration were higher in hypertensive patients with than in those without concentric hypertrophy. In a multiple regression model there was a strongly significant correlation between the degree of left ventricular mass index and the severity of hypertensive retinopathy and renal involvement, independent of office blood pressure. CONCLUSIONS: These results clearly demonstrate that echocardiographically determined left ventricular mass and geometry stratify extracardiac target organ damage in patients with essential hypertension more closely than office blood pressure. The present study also suggests that, in addition to blood pressure load, the renin-angiotensin-aldosterone system appears to play an important role in myocardial hypertrophy and peripheral vascular damage in hypertension.

Aldosterone↗
PubMed1995

Contractile properties of left ventricular myocytes isolated from spontaneously hypertensive rats: effect of angiotensin II.

OBJECTIVE: This study was undertaken to clarify whether the myocardial dysfunction observed in the hypertensive heart is an intrinsic property of the myocyte or not. MATERIALS AND METHODS: We investigated left ventricular function and contractile function of myocytes from 30-week-old spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). We also evaluated the effect of angiotensin II on contractile function of myocytes from both rats. RESULTS: The time constant of isovolumic pressure fall was significantly greater in SHR (13.2 +/- 0.6 ms) than in WKY (10.3 +/- 0.5 ms). The extent of shortening in isolated myocytes was significantly higher in SHR (11.3 +/- 0.4%) than in WKY (9.8 +/- 0.4%, P<0.01). Both the normalized maximal velocity of shortening and the normalized maximal velocity of relengthening were significantly greater in SHR (2.12 +/- 0.08 and 2.10 +/- 0.08 s-1; both P<0.01) than in WKY (1.76 +/- 0.06 and 1.75 +/- 0.07 s-1). Angiotensin II caused significant decreases in the extent of shortening, the normalized maximal velocity of shortening and the normalized maximal velocity of relengthening in isolated myocytes from SHR, but these parameters were unchanged in WKY. CONCLUSIONS: These results suggest that left ventricular diastolic dysfunction in SHR is not due to an intrinsic abnormality of the cardiac myocytes, and that angiotensin II suppresses the function of myocytes from hypertrophied hearts.

Animals↗
PubMed1995

Effect of age on left ventricular geometric patterns in hypertensive patients.

OBJECTIVES: To investigate the effect of age on left ventricular structure and geometry in hypertensive patients, we studied the relationship between age and echocardiographic variables in patients with uncomplicated essential hypertension. PATIENTS AND METHODS: We divided 168 patients with hypertension into three groups according to age: young (<40 years), middle-aged (40-59 years) and an elderly group (> or = 60 years). They were further categorized according to relative wall thickness and the left ventricular mass index. We then evaluated the prevalence of left ventricular geometric patterns in these patients according to age. RESULTS: The left ventricular end-diastolic dimension decreased with age, both in normotensive control subjects and in hypertensive patients. The magnitude of this decrease was similar for both. The relative wall thickness and left ventricular mass index were greater in the hypertensive patients than in the normotensive control subjects, and these increased with age both in the controls and the hypertensives. The differences between normotensives and hypertensives in these variables remained unchanged with age. The prevalence of a normal left ventricle (normal relative wall thickness and left ventricular mass index) in the hypertensive patients decreased with age. Conversely, the prevalence of concentric remodeling (increased relative wall thickness with normal left ventricular mass index) and concentric hypertrophy (increased relative wall thickness and left ventricular mass index) increased with age. CONCLUSIONS: These results demonstrate that age significantly affects left ventricular structure both in normotensive control subjects and in hypertensive patients. Thus, the differences in left ventricular geometric patterns with age may have important implications in assessing left ventricular structure and geometric patterns in hypertensive patients.

Adult↗
PubMed1994

Labeling of v-Src and BCR-ABL tyrosine kinases with [14C]herbimycin A and its use in the elucidation of the kinase inactivation mechanism.

The ansamycin antibiotic, herbimycin A, selectively inactivates cytoplasmic tyrosine kinases, most likely by binding irreversibly to the reactive SH group(s) of kinases. To further investigate the mechanism of herbimycin A action, we attempted to label tyrosine kinases with [14C]herbimycin A. p60v-src and p210BCR-ABL in immune complexes were labeled with [14C]herbimycin A, demonstrating that the antibiotic binds directly to tyrosine kinases. Digestion of [14C]herbimycin A-labeled p60v-src with Staphylococcus aureus V8 protease revealed that the herbimycin A binding site is within the C-terminal 26-kDa fragment of p60v-src, which contains the tyrosine kinase domain. Herbimycin A treatment inhibited labeling of p60v-src by [14C]fluorosulfonylbenzoyl adenosine, an affinity labeling reagent of nucleotide binding sites, indicating that herbimycin A-modified p60v-src cannot interact with ATP. The results suggest that herbimycin A inactivates tyrosine kinases by binding directly to the kinase domain, thereby inhibiting access to ATP.

3T3 Cells↗
PubMed1994

Maturation-related biochemical changes in swine anterior cruciate ligament and tibialis posterior tendon.

In order to determine the differences between ligaments and tendons in terms of change in biochemical composition during maturation, the biochemical characteristics of the anterior cruciate ligament and tibialis posterior tendon of swine were studied. The collagen content of the tibialis posterior tendon was found to increase rapidly with growth of the body, reaching a plateau prior to maturation. In contrast, the rate of increase in the anterior cruciate ligament was slow, indicating that maturation of this tissue is delayed. The quantity of glycosaminoglycan in both the anterior cruciate ligament and the tibialis posterior tendon decreased with growth. In mature animals, glycosaminoglycans in the anterior cruciate ligament included chondroitin sulfate, hyaluronic acid, and dermatan sulfate, but only trace amounts of chondroitin sulfate were found in the tibialis posterior tendon. Although the ratio of dermatan sulfate to hyaluronic acid generally increased with growth, this increase was more conspicuous in the tibialis posterior tendon than in the anterior cruciate ligament. The anterior cruciate ligament and tibialis posterior tendon both contained collagen of types I, III, and V. In mature swine, type III was increased in the anterior cruciate ligament but not in the tibialis posterior tendon. These findings demonstrate slower maturation for ligament than for tendon with regard to the changes in biochemical constituents, especially those in collagen type and glycosaminoglycan, during the growth process, and also suggest that the composition of these tissues changes in accordance with their changing functional requirements.

Animals↗
PubMed1994

Inhibitory effect of interleukin-2 on histamine release from rat mast cells.

Interleukin-2 (IL-2) inhibited histamine release from rat mast cells induced by compound 48/80 in a concentration-dependent manner. The inhibitory effect of IL-2 on histamine release was also dependent on the length of the incubation period; the maximum inhibition was achieved at 8 h after IL-2 addition. Furthermore, IL-2 inhibited not only IP3 production but also 45Ca uptake in mast cells stimulated by compound 48/80. Since IL-2 enhanced [3H]-leucine uptake into mast cells, this suggests that protein synthesis may be related in some way with the inhibition of histamine release. IL-2 treatment augmented the synthesis of a protein having a molecular weight of approximately 35 kDa. From Western blotting analysis, it became clear that the production of lipocortin-I was augmented in rat mast cells by IL-2 treatment. The present study shows that IL-2 induces the synthesis of lipocortin-I in mast cells and that lipocortin-I may play some role in inhibiting histamine release from mast cells.

Animals↗
PubMed1994

Usefulness of magnetic resonance imaging for detecting intrasubstance tear and/or degeneration of lateral discoid meniscus.

In order to determine the usefulness of magnetic resonance imaging (MRI) for detection of intrasubstance tears or degeneration of the lateral discoid meniscus, we compared findings obtained with MRI with those of histological examination. Sixty-four symptomatic lateral discoid menisci were studied using MRI before surgical treatment. Of these, 18 (28%) met the criteria that MRI signals did not extend to the surface and that no visible tears were observable at arthroscopy. Findings of intrameniscal regions of high signal intensity and flattening in shape on MR images were found to represent intrasubstance tears or degeneration not detected at arthroscopy. Our findings thus demonstrate that MRI is more sensitive than arthroscopy in the detection of intrasubstance pathologies of the lateral discoid menisci.

Adolescent↗
PubMed1994

Contractile dysfunction in the diabetic-rat heart is an intrinsic abnormality of the cardiac myocyte.

1. In order to clarify whether the myocardial dysfunction observed in diabetic-rat hearts is an intrinsic property of the myocytes or not, we investigated cardiac function and myocyte contractile function in diabetic rats 5 weeks after the injection of streptozotocin. 2. Maximal and minimal dP/dt and time constant of isovolumic pressure fall were measured using a micromanometer in diabetic and age-matched control rats. 3. Isolated myocytes were enzymically obtained from each rat heart and were stimulated at 1 Hz (37 degrees C) in a buffer containing 1.5 mmol/l Ca2+. The images of myocyte contractions were recorded by a video system. Normalized maximal velocity of shortening (maximal velocity of cell shortening/resting cell length; s-1), normalized maximal velocity of relengthening (maximal velocity of cell relengthening/resting cell length; s-1) and extent of shortening [(twitch amplitude/resting cell length) x 100; %] were analysed by a digitalized computer as contractile functions of the myocyte. 4. The maximal and minimal dP/dt in diabetic rats (7876, 5341 mmHg/s) were significantly lower than those in control rats (9349, 7876 mmHg/s). The time constant of isovolumic pressure fall in diabetic rats (12.7 ms) was significantly greater than that in control rats (8.6 ms). Moreover, the normalized maximal velocity of shortening, normalized maximal velocity of relengthening and extent of shortening in myocytes from diabetic rats (1.40 s-1, 1.38 s-1, 9.5%) were significantly lower than those in myocytes from control rats (1.64 s-1, 1.60 s-1, 11.8%). 5. These results suggest that contractile impairment in this diabetic-rat heart model is mainly due to an intrinsic abnormality of the cardiac myocytes.

Animals↗
PubMed1994

Effects of azelastin on pruritus and plasma histamine levels in hemodialysis patients.

BACKGROUND: Persistent pruritus is the most common symptom in hemodialysis patients. Its causes are poorly understood and there is no effective treatment. We have studied the effect of azelastin HCL on the plasma histamine concentrations and pruritus in maintenance dialysis patients with or without erythropoietin therapy. PATIENTS: Twenty-eight hemodialysis patients were divided into four groups according to the presence or absence of pruritus and whether or not they received erythropoietin therapy. RESULTS: Histamine concentrations in the patient groups were significantly higher than in healthy volunteers, but a significant difference could not be found among the four groups. The patients with pruritus showed no change in their histamine concentration during treatment with azelastin HCL, but their pruritus scores decreased remarkably. CONCLUSIONS: The present data do not support the thesis that the increased plasma histamine concentration is causally related to pruritus in hemodialysis patients or that the antiallergic drug, azelastin HCL, alleviates the pruritus of dialysis patients by decreasing plasma histamine levels. The possible role of the increased tissue levels of histamine remains to be studied.

Adult↗
PubMed1994

Expression of multidrug resistance gene product (P-glycoprotein) in transitional cell carcinomas of the upper urinary tract.

We assessed the expression of P-glycoprotein, the product of the multidrug resistance gene, in 107 specimens from patients with transitional cell carcinoma of the upper urinary tract, using an immunohistochemical method with a polyclonal antibody. P-glycoprotein was expressed in 28 of 107 (26%) specimens. While P-glycoprotein expression was not related to the grade or stage of these tumors, the incidence of P-glycoprotein in specimens with tumors which coexisted in renal pelvic and ureter is significantly higher than those with either renal pelvic or ureter tumor alone. In the patients with advanced upper urinary tract tumor who had adjuvant chemotherapy including at least one P-glycoprotein-transported drug (mdr regimen), overall survival of patients with P-glycoprotein-positive tumor was significantly shorter than that of patients with negative tumor. This pilot study demonstrates that P-glycoprotein can be expressed in one fourth of transitional cell carcinomas of the upper urinary tract and that P-glycoprotein expression serves as a prognostic indicator in patients with these tumors who are treated with mdr regimens.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

Myocardial scintigraphic characteristics in patients with primary aldosteronism.

To evaluate the difference in myocardial damage between primary aldosteronism and untreated essential hypertension, we performed thallium-201 myocardial single-photon emission computed tomography in 10 patients with primary aldosteronism and 10 patients with essential hypertension who were matched for age, sex, blood pressure, and the severity of left ventricular hypertrophy for primary aldosteronism. From the analysis of thallium-201 myocardial scintigraphy, extent score was calculated. Extent score was significantly higher in primary aldosteronism than in essential hypertension (45.8 +/- 23.5% versus 9.5 +/- 7.3%, P < .01). After operation, blood pressure significantly decreased, and the precordial voltages (SV1 + RV5) and left ventricular mass indexes were significantly reduced in patients with primary aldosteronism. Extent score was also significantly improved. These results suggest that despite the same severity of myocardial hypertrophy between primary aldosteronism and essential hypertension, the myocardial damage estimated by thallium-201 myocardial scintigraphy is more severe in primary aldosteronism than in essential hypertension. Extent score was useful for evaluation of the severity of myocardial damage in hypertensive patients.

Echocardiography↗
PubMed1994

Evaluation of aortic distensibility in patients with essential hypertension by using cine magnetic resonance imaging.

In order to evaluate the exact distensibility in various parts of aorta in hypertensive patients, the authors performed cine magnetic resonance (MR) in 30 normal control (NC) subjects and 30 hypertensive (HT) patients whose age and sex were matched. Cine MR was carried out at transverse sections in the ascending, descending, and abdominal aorta. Aortic diameter and area were measured in the frames of the maximum and the minimum aortic area. Aortic distensibility was calculated from the following formula: (Max area-Min area)/(Min area x delta P), where delta P is pulse pressure. Cardiac parameters were measured with echocardiography in all subjects. Aortic distensibility was significantly lower in HT patients than in NC subjects at each transverse section (P < 0.01). Minimum diameter index (Min diameter/body surface area) and cardiac function parameter showed no significant differences between NC and HT groups. From these findings, it is suspected that hypertension is a strongly contributing factor that promotes aortic sclerosis.

Adult↗
PubMed1994

Isolated congenital left ventricular diverticulum in an adult. A case report.

A sixty-three-year-old man presented himself with atrial flutter and congestive heart failure. Cardiac catheterization revealed that left ventricular diverticulum was located on the anterobasal wall with narrow connection to the left ventricular cavity. Coronary angiography revealed normal coronary arteries. The patient had been asymptomatic until adult life with no other thoracoabdominal or cardiac anomalies. This is an extremely rare finding in the adult population.

Atrial Flutter↗
PubMed1994

Evaluation of short axial blood flow pattern in thoracic descending aorta by use of tagging cine magnetic resonance.

The authors, for the first time, evaluated the short axial blood flow profile by using tagging cine magnetic resonance (MR). Cine MR was performed on 15 healthy volunteers aged 51.5 +/- 23.1 (SD) years. The transverse plane of the thoracic descending aorta was imaged at the middle level of the left ventricle. Two or four radial tags, whose thickness was 3 mm width each, were established to the short axial image of the descending aorta at 2 msec and 300 msec following the R wave of the subjects' QRS complex on the electrocardiogram. They observed the flow patterns and measured the rotating flow velocity of the thoracic descending aorta in early systole and late systole from the following formula: v = d/t, (v = velocity, d = displacement of tags over the interval, t = time interval between the time of presaturation and the time of imaging). In the short axial image of the descending aorta, 13 subjects showed the clockwise rotation of tags in the supine position from the foot side view. Flow image of the other 2 subjects showed as undefined. Rotating flow velocity was 1.63 +/- 0.88 cm/sec in early systole and was 1.37 +/- 1.11 cm/sec in late systole. Tagging cine MR is useful to evaluate the blood flow profile in the thoracic descending aorta.

Adult↗
PubMed1994

In vivo microdialysis for pharmacokinetic investigations: a plasma protein binding study of valproate in rabbits.

The use of microdialysis to study the binding of valproate (VPA) to plasma proteins was evaluated in rabbits. Prior to an in vivo microdialysis, in vitro relative recovery of VPA respectively from Ringer's solution, 5% (w/v) of albumin solution and plasma sample via a microdialysis probe was examined. The in vitro relative recovery was defined as a ratio of the VPA concentration determined in the dialysate to the free VPA concentration in the sample solution surrounding the membrane of the microdialysis probe. When the sample solution was well stirred at 700 rpm and maintained at 37 degrees C, the in vitro relative recovery of VPA was significantly different among them. It increased in the order of Ringer's solution (34.3 +/- 2.6%) > 5% (w/v) of albumin solution (25.7 +/- 4.6%) > rabbit plasma sample (15.8 +/- 1.2%). Thereafter, pharmacokinetics of VPA was determined using both microdialysis sampling via the rabbit femoral vein and collection of whole blood via the rabbit ear vein after intravenous administration of VPA at a dose of 43 mg/kg. Free concentrations of VPA in plasma were determined by ultrafiltration method as opposed to microdialysis method. There was no difference in the elimination half-life of VPA determined by microdialysis, 1.09 +/- 0.22 h, or ultrafiltration, 1.22 +/- 0.21 h. The AUC of VPA in dialysate was 15 +/- 4 micrograms.h/ml, which corresponded to 15% of that in ultrafiltrate (103 +/- 17 micrograms.h/ml). The value was in good agreement with the in vitro relative recovery of VPA from plasma sample (15.8 +/- 1.2%).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗