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Biomedical subjects

Y Yoshimura

Publications and source records attributed to Y Yoshimura.

At least 397 records · Page 22Linked to original sources
PubMed1991

Involvement of leukotriene B4 in ovulation in the rabbit.

The present study was undertaken to assess the effects of lipoxygenase products on ovulation, oocyte maturation, and steroid production in the perfused rabbit ovary preparation. Ovulatory efficiency was significantly reduced when rabbit ovaries were perfused with human CG (hCG) plus nordihydroguaiaretic acid (NDGA) at 10(-5) or 10(-6) M, as compared to contralateral hCG-treated controls. The addition of NDGA to the perfusate inhibited hCG-induced ovulation in a dose-related manner. The percentage of ovulated ova and follicular oocytes achieving germinal vesicle breakdown did not differ significantly between NDGA-treated ovaries and contralateral controls. Leukotriene B4 (LTB4) production by the perfused rabbit ovaries reached its maximum 6 h after exposure to hCG and then declined. The addition of NDGA at 10(-5) M significantly inhibited hCG-stimulated LTB4 production by rabbit ovaries throughout the entire perfusion periods. The ovulatory efficiency in ovaries treated with hCG alone or with hCG plus NDGA correlated significantly with LTB4 production by perfused rabbit ovaries 6 h after exposure to hCG (alpha = 0.8893, P less than 0.01). Furthermore, the addition of LTB4 at 100 ng/ml to the perfusate reversed the inhibitory effects of NDGA on hCG-induced ovulation. However, exposure to NDGA affected neither progesterone nor estradiol production elicited by hCG administration. These results suggest that NDGA may block hCG-induced ovulation in vitro, probably via the inhibition of LTB4 production by rabbit ovaries.

Animals↗
PubMed1991

Changes in convulsion susceptibility of lidocaine by alteration of brain catecholaminergic functions.

Influences of the manipulation of brain catecholaminergic neuronal activity on the incidence of lidocaine-induced convulsions in mice were studied and compared with those of pentylenetetrazol (PTZ)-induced convulsions. alpha-Methyl-p-tyrosine (alpha-MPT) decreased both brain noradrenaline (NA) and dopamine (DA) levels, and disulfiram decreased the NA level and increased the DA level. The incidence of lidocaine-induced convulsions was decreased by treatments with alpha-MPT and disulfiram, while that of PTZ was increased by either treatment. The incidence of lidocaine-induced convulsions was slightly, but not significantly increased by L-dihydroxyphenylalanine (L-DOPA), although the brain DA level was increased by L-DOPA. Methamphetamine and desipramine increased the incidences of lidocaine-induced convulsions. These results may suggest that brain catecholaminergic neurons, differing from their role in inhibiting control of PTZ-seizure, act to facilitate lidocaine-induced convulsions.

Animals↗
PubMed1991

Uptake of nicotinamide by rat pancreatic beta cells with regard to streptozotocin action.

Exposure of rat pancreatic beta cells in monolayer culture to 2 mmol streptozotocin (STZ)/l for 1 h followed by thorough washing inhibited their uptake of [14C]nicotinamide and [3H]2-deoxyglucose [( 3H]2-DG) to about 50% and also reduced the intracellular ATP concentration to 50% of that in control cells. These changes were not due to a lethal cytotoxic effect of STZ, because cell viability, as estimated by succinic dehydrogenase activity, was 90% of that of control cells. Oligomycin and carbonylcyanide-m-chlorophenylhydrazone (CCCP), an uncoupler of oxidative phosphorylation, caused a dose-dependent decrease in intracellular ATP concentration while maintaining high cell viability. These ATP-depleted cells showed a decrease in insulin release and an inhibition of the uptake of [14C]nicotinamide and [3H]2-DG in a dose-dependent manner. Therefore oligomycin and CCCP reproduced the same effects as those found in beta cells treated with STZ. These results suggest that the uptake of nicotinamide and 2-DG by beta cells might be regulated by their intracellular ATP concentration. The decreased uptake of nicotinamide in ATP-depleted beta cells caused by STZ might explain the lack of protective effect of nicotinamide against STZ cytotoxicity when administered after the latter. Furthermore, the radiotracer experiments demonstrated that the transport of nicotinamide by intact beta cells was inhibited in a dose-dependent manner by 2-DG and vice versa, i.e. the transport of 2-DG was inhibited by nicotinamide. These findings suggest the existence of a common transport mechanism in beta cells responsible for the uptake of nicotinamide and 2-DG, the transport of which is known to occur by facilitated diffusion.

Adenosine Triphosphate↗
PubMed1991

The ultrastructure of cartilage formation from neonatal skeletal muscle in vitro.

Histological changes in cultured neonatal skeletal muscle tissue at the early stage of cartilage induction by syngeneic insoluble bone matrix gelatin (BMG) containing bone morphogenetic protein were examined by light and electron microscopy. Minced skeletal muscle was cultured on hemicylindrical pieces of BMG for 14 days. Chondroblasts first appeared in the crevices of the BMG on Day 7 of the culture, and cartilage tissue was seen to fill the crevices completely by Day 10. The main findings in this work are as follows: 1) the activation of satellite cells and necrosis of myonuclei; 2) the migration of satellite cells from the basement membrane; 3) fibroblasts with increased numbers of organelles between degenerated muscle fibers closely resembling the migratory satellite cells; 4) the migration of the spindle-shaped cells into the crevices of the BMG; and 5) change of the spindle-shaped cells to chondroblasts. These findings suggest that neonatal skeletal muscles, which appear more mature than embryonic muscles, also have a chondrogenetic potential when grown on BMG, and that chondroblasts originate from the spindle-shaped cells which are thought to result from migratory satellite cells as well as fibroblasts.

Animals↗
PubMed1991

Oxygen dependence of lipid peroxidation in mice.

Peroxidation of lipids in serum and tissues of mice placed in low or high levels of oxygen was examined. After exposure to 100% oxygen for 3 h, no significant differences were observed between control and exposed mice. However, exposure to 100% oxygen for 6 h resulted in a decrease in oxygen consumption, an increase in lipid peroxides in tissues and serum, and the formation of hydroxyl radicals in tissues and serum. At low concentrations of oxygen (14% or 16%), a decrease in oxygen consumption, peroxidation of lipids and formation of hydroxyl radicals also were observed. Damage to mice was great with the lower oxygen concentrations of oxygen. There was a close correlation between the consumption of oxygen lipid peroxidation, formation of hydroxyl radicals.

Animals↗
PubMed1991

Architecture of implanted bone matrix gelatin influences heterotopic calcification and new bone formation.

Heterotopic bone formation in skeletal muscle induced by compacted demineralized bone matrix gelatin (BMG) was studied histologically and biochemically. BMG was obtained by dehydrating diaphyseal shafts of femora and tibiae of 4-week-old male Sprague-Dawley rats, cutting the bone into chips, and demineralizing and extracting the chips with various solutions. The BMG was treated with 4 M guanidine-HCl, and compacted BMG was prepared by centrifugation. The compacted BMG was implanted into the rectus abdominis muscle of 5-week-old male Sprague-Dawley rats. The resulting specimens were examined histologically, and their alkaline phosphatase activity and the calcium content of the tissues were measured 3, 5, 7, 10, and 15 days after implantation. The BMG (separated BMG) with 75- to 500-microns particle sizes were implanted into control rats. The results showed that calcification, alkaline phosphatase activity, and bone formation were suppressed by implantation of the compacted BMG and that scarcely any vascularization occurred. Calcification, vascularization, and alkaline phosphatase activity were related and were indispensable for bone formation. In the control group, bone formation was observed at sites of high activity of alkaline phosphatase and well-developed vascularization. These results suggested that compacting of BMG suppressed vascularization, decreased calcification, and consequently reduced the induction of bone formation.

Alkaline Phosphatase↗
PubMed1991

Localization of progesterone receptors in the shell gland of laying and nonlaying chickens.

The aim of the present study was to localize the progesterone receptor (PR) in the shell gland of the chicken and to determine if the localization and the amount of PR in the shell gland change with egg laying activity. White Leghorn hens laying regularly or out of lay for more than 2 wk were used. Localization of PR in the shell gland was done by immunocytochemistry. The amount of PR in the shell gland mucosal tissues was measured by Western blot analysis. Monoclonal antibodies to the chicken PR, PR6, and PR13 were used in both experiments. The PR were present in the nuclei of the surface epithelial cells, tubular gland cells, stromal fibroblasts, and smooth muscle cells in the arterial wall and myometrium of laying hens. The PR were localized in the same tissues of the shell gland of nonlaying hens as in laying hens. However, the density of PR-positive cells in nonlaying hens was greater, possibly because the tissues were atrophied. Western blot analysis indicated that the amount of PR was greater in nonlaying hens than in laying hens when equal amounts of proteins were used, whereas the molecular weights of PR of laying and nonlaying hens were identical. These results suggest that progesterone acting through its receptor may regulate the secretory activity of the surface epithelium and tubular gland cells for shell formation and the contractile activity of the myometrium. Moreover, once the cells of the shell gland differentiate and become responsive to progesterone, these cells maintain this responsiveness even during the nonlaying period.

Animals↗
PubMed1991

Studies on condensed-heterocyclic azolium cephalosporins. I. Synthesis and antibacterial activity of 7 beta-[2-(2-aminothiazol-4-yl)-2(Z)- alkoxyiminoacetamido]-3-(imidazo[1,2-a]pyridinium-1-yl)methyl-3- cephem-4-carboxylates.

In our study of the structure-activity relationships of cephalosporins bearing quaternary ammonium groups at the 3 position, we postulated that delocalization of the azolium positive charge would lead to an expanded antibacterial spectrum and increased activity. Since quaternization of condensed-heterocyclic compounds such as imidazo[1,2-a]pyridine gives positive charge delocalization, 7 beta-[2-(2-aminothiazol-4-yl)-2(Z)-alkoxyiminoacetamido] cephalosporin derivatives (1-53) bearing various (imidazo[1,2-a]pyridinium-1-yl)methyl moieties at the 3 position were prepared and their antibacterial activity was determined. As expected, these cephalosporins exhibited potent activity against both Gram-positive and Gram-negative bacteria including Pseudomonas aeruginosa. These results imply that imidazo[1,2-a]pyridine is a quite useful substituent for improving antibacterial activity and spectrum. The structure-activity studies revealed that a favorable substituent on the imidazo[1,2-a]pyridine is the cyano radical at the 6 position of the ring, and ethoxyimino or 1-carboxy-1-methylethoxyimino groups are suitable for the alkoxyimino substituent. Among the cephalosporins tested, 7 beta-[2-(2-aminothiazol-4-yl)-2(Z)- ethoxyiminoacetamido]-3-(6-cyanoimidazo[1,2-a]pyridinium -1-yl)methyl-3-cephem-4-carboxylate (45) and 7 beta-[2-(2-aminothiazol-4-yl)-2(Z)-(1- carboxy-1-methylethoxyiminoacetamido]-3-(6-cyanoimidazo[1,2- a] pyridinium-1-yl)methyl-3-cephem-4-carboxylate (49) showed good antibacterial activity.

Cephalosporins↗
PubMed1991

Studies on condensed-heterocyclic azolium cephalosporins. II. Synthesis and antibacterial activity of 7 beta-[2-(2-aminothiazol-4-yl)-2(Z)-alkoxyiminoacetamido]-3-(condensed- heterocyclic azolium)methyl-3-cephem-4-carboxylates.

From our series of studies on cephalosporins bearing condensed-heterocyclic azolium methyl groups at the 3 position in the cephalosporin nucleus, we describe here the synthesis and antibacterial activity of 7 beta-[2-(2-aminothiazol-4-yl)-2(Z)-alkoxyiminoacetamido]ceph alosporins containing imidazo[1,5-a]pyridinium, imidazo[1,2-b]pyridazinium, imidazo[1,2-a]pyrimidinium, imidazo[1,2-c]pyrimidinium, and pyrazolo[1,5-a]pyridinium methyl groups at the 3 position. Among the cephalosporins tested, 7 beta-[2-(2-aminothiazol-4-yl)-2(Z)-methoxyiminoacetamido]-3- (imidazo[1,5-a]pyridinium-2-yl) (1), (imidazo[1,2-b]pyridazinium-1-yl) (2), and (pyrazolo[1,5-a]-pyridinium-1-yl) (3)methyl-3-cephem-4-carboxylates showed potent antibacterial activity and broad antibacterial spectrum. The antibacterial activity of these cephalosporins (1 approximately 3) was superior to that of ceftazidime (CAZ). These results imply that the delocalization of the positive charge of the imidazo[1,5-a]pyridinium, pyrazolo[1,5-a]pyridinium and imidazo[1,2-b]pyridazinium groups leads to an expanded antibacterial spectrum and increased activity and that these condensed-heterocyclic compounds as well as imidazo[1,2-a]pyridine are effective moieties for improving antibacterial activity and spectrum.

Cephalosporins↗
PubMed1991

[The effect of sex hormones on tubular aggregates in normal mouse skeletal muscles].

Although tubular aggregates (TAs) are nonspecific findings observed in various neuromuscular disorders, they are specifically recognizable in the muscles of patients with periodic paralysis. However, their function and significance are still unknown. We have previously reported that TAs were observed in normal male, but not in female mouse muscles. To clarify the effects of sex hormones on morphogenesis of TAs, the following studies were performed. In normal male mice (ICR/JCL, N = 102), TAs began to appear at 3-4 months, and were seen in all animals above 6-7 months of age. On the other hand, in normal female mice (N = 50), TAs were observed in only 2 mice, at 14 and 18 months of age. When mice were castrated (N = 69: male 34/female 35), TAs were not found in either males or females. The results suggested that there is a close relationship between TA formation and male hormone. Testosterone propionate (TP) was administered to both castrated and un-castrated mice (N = 167: male 84/female 83). TAs were not found in castrated, TP 10 mg/2M implanted mice (N = 22: male 12/female 10). When TP was increased to 20 mg/1M, TAs began to appear in both male and female, castrated and un-castrated mice at 3 months, and were observed in 100% of mice, except female un-castrated mice, older than 4-5 months of age. Accordingly, a fairly large amount of TP above a certain threshold and a long incubation time of at least 3 months is necessary to induce TAs in the skeletal muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[A case of idiopathic calcinosis of the scrotum].

We report a case of idiopathic calcinosis of the scrotum. The patient was a 33-year-old male with a complaint of multiple scrotal nodules, from which white chalky materials occasionally broke out. The nodules were first noticed 17 years ago, and since then gradually increased in size and number. Sometimes he had felt itching on the scrotum, but otherwise he had been in good health. Blood analysis and biochemical analysis revealed normal findings. In addition, there were no abnormal findings in serum electrolyte analysis including calcium and phosphate concentrations. Analysis of the intra-nodular content by infrared spectrophotometry showed that it consisted of calcium phosphate (52%) and magnesium ammonium phosphate (48%). We reviewed the literature and discuss the etiology of this disease.

Adult↗
PubMed1991

Muscle tissue reactions to implantation of bone matrix gelatin.

Histologic changes of muscle tissue in the early stage of heterotopic osteogenesis induced by syngeneic insoluble bone matrix gelatin (BMG) with bone morphogenetic protein in rats was observed by light and electron microscopy. BMG induced cartilage in muscle tissue by Day 7 after its implantation, woven bone by Day 10, and lamellar bone with bone marrow by Day 14. The new findings in this work include (1) the disappearance of the basement membrane of muscle fibers; (2) the activation of the satellite cells of muscle fibers; (3) the appearance of fibroblastlike cells that closely resembled activated satellite cells among the degenerated muscle fibers or on the surface of the BMG; and (4) the change of fibroblastlike cells to chondroblasts or osteoblasts. These findings suggest that intramuscular implantation of BMG caused the conspicuous disappearance of the basement membrane of the muscle fiber and may play a part in osteogenesis induced by BMG.

Animals↗
PubMed1991

Subperiosteal implantation of bone morphogenetic protein adsorbed to hydroxyapatite.

Bone development was induced by bone morphogenetic protein (BMP) adsorbed to hydroxyapatite (HAP) under the periosteum of rat parietal bone. The BMP was isolated by Sephacryl-S200 column chromatography after passage through a membrane filter system. The yield of the fraction with BMP activity was 20 times greater than yields obtained by conventional methods. BMP was adsorbed to HAP in vacuo. HAP alone was implanted as a control. The formation of cartilage and bone was observed seven days after the implantation of BMP-HAP, and the newly formed bone fused with the host calvaria after 28 days. In control rats, no bone formation was seen within 56 days after implantation. The BMP-HAP complex was more effective in induced periosteal bone formation than HAP only.

Adsorption↗
PubMed1990

[Study on endoscopic features in responders to systemic chemotherapy in advanced gastric cancer].

We studied the endoscopic features in 6 cases of advanced gastric cancer responded to chemotherapy. Patient characteristics were as follows. [table; see text] Age 43-77 (mean 63 years old) Endoscopic type Mean duration of PR was 26.6 weeks. The process of the improvement of primary lesion as judged by endoscopic findings were as follows. Firstly getting flat of wall, secondly reduction in size of ulcer, and lastly changing into scar. Number of reported cases including our case No. 6 which are diagnosed as scar endoscopically after chemotherapy and are operated successfully has been increasing. Most of them showed scar macroscopically with wide and irregular surface. Especially our case No. 6 showed keloidal scar. In these cases, the histological improvement into grade 2-3 was observed in scared tissue. Sooner or later, such a process of endoscopic improvement was observed 4-8 weeks after initiation of chemotherapy. Unless the endoscopic improvement was observed 8 weeks after initiation, regimen of chemotherapy should be changed into others.

Adult↗
PubMed1990

Contents of tissue CEA and CA19-9 in colonic polyp and colorectal cancer, and their clinical significance.

In precancerous states or early cancer, the serum levels of tumor markers are almost not detectable. Therefore, the tissue contents of CEA and CA19-9 were measured in 48 colonic polyps, 8 colorectal cancers and 5 normal colonic mucosa. These tissue specimens were obtained by endoscopic polypectomy, surgery or autopsy, and homogenated in normal saline (10 ml/wet g of tissue). After centrifugation, the supernatant was assayed by enzyme or radioimmunoassay. There was no correlation between serum levels and tissue contents of CEA or CA19-9 in colonic adenomas and colorectal cancers. The mean contents of tissue CEA and CA19-9 in colonic polyp and colorectal cancer were significantly higher than normal colonic mucosa, and the highest contents of CEA and CA19-9 were found in colorectal cancer. The contents of tissue CEA and CA19-9 in cancerous regions were markedly increased as compared with noncancerous regions. In adenomas, there was a relationship between the degree of histological dysplasia and the tissue content of CEA. Relationships were also found between macroscopic findings and tissue tumor markers in adenomas. These results suggest the possibility that the measurement of tissue tumor markers may be useful for borderline colonic lesions.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed1990

Pilomatrixoma of the preauricular region.

Pilomatrixoma is a relatively rare benign skin neoplasm, which is generally present as a single, asymptomatic dermal or subcutaneous nodule, which occurs most often in the first 2 decades of life with a higher incidence in females. The usual sites are the face and upper extremities. This paper describes a case of such a tumour presenting in the right preauricular region of a 14-year-old Japanese girl.

Adolescent↗