Search PubMed⌕ Search

Biomedical subjects

M Morikawa

Publications and source records attributed to M Morikawa.

At least 217 records · Page 12Linked to original sources
PubMed1989

Bay K 8644-induced potentiation of the contractile response of rabbit iliac artery to caffeine in a Ca2+-free medium.

1. In a Ca2+-free medium caffeine (10 mM) was still able to cause a phasic contraction in rabbit iliac arteries. 2. Bay K 8644 at 10(-6) but not at 10(-7) M potentiated the residual response to caffeine in a Ca2+-free medium. In a Ca2+-free medium with or without KCl (40 mM), Bay K 8644, however, caused no contraction. 3. Nifedipine (10(-6) M) did not affect the residual caffeine-response or the potentiating effect of Bay K 8644. Verapamil (10(-6) M), however, inhibited both the caffeine response and the potentiation. 4. Bay K 8644 (10(-6) M) potentiated the contractile response to Ca2+ (0.01-2.4 mM) in a Ca2+-free medium containing KCl. The potentiation was equally inhibited by nifedipine or verapamil. 5. La#+ (1 mM), EGTA (0.1 mM), or vanadate (10(-4) M) completely inhibited the Bay K 8644-induced potentiation without affecting the residual caffeine response. 6. These results suggest that the potentiating action of Bay K 8644 on the residual caffeine response in a Ca2+-deficient medium may not be related to voltage-dependent Ca2+ channels. In addition, the activity of Ca2+-ATPase in sarcolemmal membranes may be important in this potentiation.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1989

Inhibitory effects of TYB 3823, a new antiarrhythmic agent, on mechanical responses in the vascular smooth muscles.

1. TYB 3823 (3 x 10(-5) M to 10(-3) M) but not lidocaine (10(-4) M) inhibited the contractile response to norepinephrine in rabbit aorta in a competitive manner. On the other hand, TYB 3823 had no effect on contractile responses to histamine, 5-hydroxytryptamine, high KCl and Ca2+. 2. In rabbit aorta, TYB 3823 (10(-5) M and 10(-4) M) but not lidocaine (10(-4) M) also antagonized the ouabain-induced contraction and this action was less potent than that of phentolamine (10(-6) M). 3. In rabbit coronary arteries precontracted with KCl (40 mM), either TYB 3823 or lidocaine inhibited the isoproterenol-induced relaxation to the same levels. Propranolol at 10(-8) M shifted the relaxation curve for isoproterenol to the right and at 10(-6) M it almost completely prevented the relaxation. Further, the effect of a combined treatment with propranolol (10(-8) M) and TYB 3823 (3 x 10(-5) M) was not different from that of a single treatment with propranolol (10(-8) M). 4. In rabbit iliac arteries, TYB 3823 (3 x 10(-5) M and 10(-4) M) but not lidocaine (10(-4) M) suppressed the contractile response to caffeine in a Ca2+-free medium with EGTA and nifedipine. Nitroglycerin (10(-4) M) also inhibited the response but this action was less potent than that of TYB 3823. The combined treatment of the tissue with TYB 3823 and nitroglycerin (both 10(-4) M) further inhibited the responses to caffeine as compared to a single treatment with each drug. 5. These results suggested that TYB 3823 may interfere with the responses due to the mobilization of intracellular Ca2+ activated by caffeine and also has both alpha- and beta-adrenoceptor blocking actions on the vascular smooth muscles.

Animals↗
PubMed1989

Structure and activity of artificial mutant variants of human growth hormone.

Four artificial mutant variants of human growth hormone (hGH) with the following characteristics were prepared in Escherichia coli by in vitro mutagenesis: (i) replacement of Trp86 with Tyr (W86Y hGH); (ii) deletion of Trp86 (delta W86 hGH); (iii) deletion of residues 32-46 (20-kd-hGH); and (iv) deletion of residues 32-71 (17.5-kd-hGH). Both W86Y hGH and delta W86 hGH have a point mutation at Trp86 which is the only Trp residue in hGH and is conserved among members of the growth hormone family. 20-kd-hGH is a minor component of hGH in the pituitary gland and plasma and is the result of an alternative splicing of the primary gene transcript, while only the corresponding mRNA and not the protein has been found in the case of 17.5-kd-hGH. The biological activities (adipogenic activity and potentiation of gain in body weight) and structures (as analyzed by circular dichroism) were mostly retained by the W86Y, delta W86 and 20-kd-hGH variants but not by 17.5-kd-hGH.

Adipose Tissue↗
PubMed1989

Structural characteristics of growth hormone receptors on mouse 3T3 cells having different biological responses to growth hormone.

Cultured 3T3-F442A preadipocytes are able to undergo GH-promoted differentiation into adipocytes. The relationship between the structure and function of GH receptors on 3T3 cells (3T3-F442A preadipocytes, differentiated adipocytes and 3T3-C2 cells, which vary in susceptibility to adipose conversion or with respect to carbohydrate and lipid metabolism) was studied by the covalent cross-linking of 125I-labelled human (h) GH to intact cells with the bifunctional reagent disuccinimidyl suberate. When preadipocytes were cross-linked and analysed using sodium dodecylsulphate-polyacrylamide gel electrophoresis, a prominent 125I-labelled hGH-receptor complex of Mr 130,000 was observed along with minor complexes (Mr 300,000, 230,000 and 60,000) on autoradiography. Non-reducing-reducing two-dimensional gel electrophoresis revealed that the higher molecular weight complexes also contained the Mr 130,000 complex. Neuraminidase and tunicamycin treatment demonstrated that the GH receptor on F442A preadipocytes is a sialo-glycoprotein with N-linked carbohydrate chains. When the differentiated 3T3-F442A adipocytes and 3T3-C2 cells (a sub-line with no susceptibility to adipose conversion with GH) were examined in the same way as 3T3-F442A preadipocytes, no differences were observed in the specificity of GH binding and in the molecular size of the 125I-labelled hGH-receptor complexes and their glycosylation characteristics. This suggests that the structural characteristics of the GH receptor are closely related in each cell type, but that the hormonal signals produced after GH binding to the receptor may cause different effects according to the cell type.

Adipose Tissue↗
PubMed1989

Analysis of abutment tooth movement utilizing mandibular kinesiography (MKG). Part 2. Effects of clasp design in unilateral free-end denture.

The three-dimensional dynamic movement of the abutment tooth was successfully analyzed on a simulation model utilizing the mandibular kinesiography. When the unilateral free-end denture retained by the RPA, RPI or Aker's clasp was subjected to various directions of loads, the abutment tooth was inclined mainly by the sliding displacement of the denture over the alveolar ridge and the lever action around the denture. The Aker's clasp assembly induced the largest tooth movement. The RPA clasp generally exhibited similar tendencies to the Aker's clasp, showing a larger tooth inclination in the disto-buccal direction. The RPI clasp seemed to be preferable for protecting the periodontal tissues from damage associated with unfavorable tooth movements since it induced less distal tooth inclination.

Dental Abutments↗
PubMed1989

[Analysis of the urinary risk factors of urolithiasis in healthy children].

Since incidence of idiopathic calcium oxalate urolithiasis in children was very low, a study was made to analyze the risk factors of calcium oxalate stone in male volunteers without any episode of urolithiasis. They were divided into four groups, group I: eight years old, group II: 11 years old, group III: 18 to 24 years old, group IV: 41 to 45 years old. Inhibitory activities of urine were significantly higher in groups of children than in groups of adults. However, inhibitory activities of filtered urine, extracted through filters with conserved limit of 25000 of molecular weight, were reduced significantly. Therefore, it was suggested that materials with molecular weight over 25000 participated in the inhibitory activities. Furthermore, the activities of filtered urine of group I were still higher than those of the non-filtered urine in groups of adults. Accordingly it was considered that substances less than 25000 of molecular weight also participated in the inhibitory activities in children. An analysis of uric acid, citrate, magnesium and uronic acid in urine revealed that magnesium excretion volume and magnesium concentration ratio to creatinine were higher in children than in adults. Magnesium seemed to boost the inhibitory activities in children. In the measurement of crystalloid materials, the concentration of calcium was significantly lower in children groups than in groups of adults. It seemed that calcium also takes part in reduction of incidence of urinary stone in children.

Adolescent↗
PubMed1989

[Radiotherapy of bone metastases from cervical cancer].

The authors have investigated 6 cases of bone metastases from cervical cancer out of a total of 90 cases of metastatic bone tumors that were irradiated for relief of associated pain at the Department of Radiology, Nagasaki University Hospital from April 1977 to March 1987. In 2 of the 6 cases, a rare, delayed recurrence with paraaortic lymph node metastases was seen. An invasion to the psoas major muscle, ilio major muscle was demonstrated by Computed Tomography after the initiation of therapy, so that the size of the field was modified. Computed Tomography was found useful to determine the exact field size for radiotherapy of metastatic bone tumor.

Aged↗
PubMed1989

The potentiation of norepinephrine-induced contraction of rabbit aorta by Mg2+ deletion in a Ca2+-free medium.

Residual responses to norepinephrine (NE) in an Mg2+-, Ca2+-free medium with low EGTA (0.1 mM) for 15 min were potentiated following preincubation of rabbit aortas in Mg2+-free medium for 60 min. Responses to Ca2+ in a Ca2+-free medium with nifedipine and NE were not affected under a similar Mg2+-free condition. Nifedipine, theophylline, dibutyryl cAMP, 8-bromo-cGMP, methylene blue, La3+ or vanadate did not affect the residual response or the potentiation. However, high EGTA (1 mM) inhibited both the residual response and the potentiation. The residual response to NE was not potentiated following incubation in Mg2+-, Ca2+-free medium for 60 min. These results suggest that, in the rabbit aorta, Mg2+ deletion from the medium selectively potentiates the residual response to NE in a Ca2+-free medium without any effect on the response due to Ca2+-influx through receptor-operated channels. This potentiation does not appear to be related to either the levels of cAMP and cGMP or the activity of an Mg2+-dependent, Ca2+-ATPase.

Animals↗
PubMed1989

[Image diagnosis of hyperparathyroidism].

Between January, 1983 and January 1988, the diagnosis of hyperparathyroidism was made on 14 patients (8 primary and 6 secondary), and was identified operatively in all. The procedures for image diagnosis were computed tomography (CT), ultrasonography and scintigraphy. Scintigraphy was performed using Tc-99m and Tl-201 by a subtraction technique. For primary hyperparathyroidism, the accuracy of localization was 100% by CT, 87.5% by ultrasonography, 100% by scintigraphy, and 100% by the combination of these three methods. For secondary hyperparathyroidism, it was 68% by CT, 68% by ultrasonography, 36% by scintigraphy and 84% by the combination of these three methods. Ultrasonography and CT were quite useful for imaging of small abnormal parathyroid glands. The accuracy of scintigraphy in secondary hyperparathyroidism was low. Because the swellings of glands do not occur equally in most secondary hyperparathyroidism cases, we consider that large glands absorb the majority of injected radionuclides. Some discussion on merits and demerits of each image procedure was done.

Adult↗
PubMed1989

[Diffusion of sulbactam and cefoperazone into the prostatic tissue].

Diffusion of sulperazone (SBT) and cefoperazone (CPZ) into the prostatic tissue was studied in 20 cases. Two g of SBT/CPZ was injected intravenously and 1 hour later, prostatic tissue was obtained surgically and venous blood was drawn simultaneously. The serum concentration of CPZ (58.0 micrograms/ml +9.2) was higher than that of SBT (25.9 micrograms/ml +/- 9.3) and the prostatic tissue concentration of CPZ (14.9 micrograms/ml +/- 6.1) was higher than that of SBT (10.9 micrograms +/- 6.1). However, the SBT concentration ratio of prostatic tissue to serum level (P/S ratio) was significantly higher (42.5%) than that of CPZ (25.9%). The SBT concentration in the prostatic tissue was high enough to enhance the antibacterial activity of CPZ. SBT/CPZ was appraised to be an effective chemotherapeutic agent for infections of prostate caused by susceptible organisms, especially by beta-lactamase producing bacteria.

Aged↗
PubMed1989

[Surgical management of acquired tricuspid valve disease--the effects and comparison of tricuspid annuloplasty (De Vega) and tricuspid valve replacement].

A total of 92 patients with tricuspid valvular disease (TR) had surgical repair of DeVega's annuloplasty in 80 patients (87%) and of valve replacement in 12 patients (13%) from January, 1978, to March, 1988. All of those patients were diagnosed by cardiac catheterization and angiogram, clinical findings and in recent cases, pulsed and color Doppler echocardiography were applied. Eighty-nine of 92 patients (97%) were in NYHA class III or IV before operation. There were 7 early death (8.5%) with DeVega procedure and one death (8.3%) in TVR and late deaths were noted in 3 patients (3.6%) (DeVega's procedure) and one (8.3%) in TVR. Two patients after DeVega procedure at 5 and 6 years were required re-operation of TVR because of recurrent mitral valvular disease. Seventy-seven of 80 survivors were in NYHA class I or II postoperatively. Twenty-seven randomized selected patients after DeVega's annuloplasty were investigated by pulsed and color Doppler echocardiography, 17 of them (63%) had no regurgitation and the remaining 10 patient had mild to moderate regurgitation. This study suggests that DeVega's annuloplasty has a simple and reliable procedure in patients with functional TR and results in excellent hemodynamic and functional effects postoperatively.

Adolescent↗
PubMed1989

[Evaluation of left ventricular function in the patients with aortic regurgitation following aortic valve replacement by radionuclide cardiography].

Twenty patients undergoing AVR were subjected to this study and divided into the early and the late groups. 6 healthy adults were dealt as the control group. The EF, PER, 1/3 EF, TPE were compared among these three groups both at rest and during exercise. The detailed responses to the exercise were measured by %delta between at rest and during exercise. Furthermore, the LV function in the filling period were examined by the 1/3 FF and RFR at rest. This study suggests that although the left ventricular function and contractile reserve to the exercise remained insufficient in the early postoperative phase, nearly complete recovery of the reserve could be obtained in the later phase, while the left ventricular function in the rapid filling period was significantly decreased in both early and late postoperative phase.

Adolescent↗
PubMed1988

Reproducibility of the vertical dimension of occlusion with an improved measuring gauge.

An improved gauge using an eyeglass frame, the TOM gauge, was devised. The reproducibility of the record of vertical dimension with this gauge was evaluated through repeated measurements on subjects having a definite centric stop with the natural dentition. Because of the stabilization provided by the frame and the reference point on the apex nasi, the TOM gauge showed excellent reproducibility of the record compared with the conventional gauges. The TOM gauge can be expected to significantly reduce the risk of errors in measuring the vertical dimension of occlusion especially in complete denture fabrication.

Chin↗
PubMed1988

Engineering of human lysozyme as a polyelectrolyte by the alteration of molecular surface charge.

The surface positive charges of human lysozyme were either increased or decreased to alter the electrostatic interaction between enzyme and substrate in the lytic action of human lysozyme using site-directed mutagenesis. The amino acid substitutions accompanying either the addition or the removal of two units of positive charge have shifted the optimal ionic strength (NaCl concentration in 10 mM Mes buffer, pH 6.2) for the lysis of Micrococcus lysodeikticus cell from 0.04 M to 0.1 M and from 0.04 M to 0.02 M respectively. In addition to the change in ionic strength-activity profile, the pH-activity profile and the effect of a polycationic electrolyte, poly-L-Lys-HCl, on the lytic activity were significantly changed. Owing to the shifts in both ionic strength profiles and pH profiles the Arg74/Arg126 mutant has become a better catalyst than wild-type enzyme under the conditions of high ionic strength and high pH, and the Gln41/Ser101 mutant has become a better catalyst under the conditions of low ionic strength and low pH.

Amino Acid Sequence↗
PubMed1988

Hemochromatosis of the pituitary gland: MR imaging.

Magnetic resonance imaging of the pituitary gland in a patient with secondary hemochromatosis is described. On T1-weighted images, the anterior lobe had almost no signal intensity, and only the high-signal posterior lobe was seen. These findings are compatible with the distribution of iron deposition and clinical symptoms in hemochromatosis.

Adult↗