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Biomedical subjects

M Oikawa

Publications and source records attributed to M Oikawa.

At least 55 records · Page 3Linked to original sources
PubMed1998

Antiherpesvirus activities of (1'S,2'R)-9-[[1',2'-bis(hydroxymethyl)cycloprop-1'-yl]methyl]guanine (A-5021) in cell culture.

Antiherpetic activity of (1'S,2'R)-9-([1',2'-bis(hydroxymethyl)cycloprop-1'yl]methyl)guanine (A-5021) was compared with those of acyclovir (ACV) and penciclovir (PCV) in cell cultures. In a plaque reduction assay using a selection of human cells, A-5021 showed the most potent activity in all cells. Against clinical isolates of herpes simplex virus type 1 (HSV-1, n = 5) and type 2 (HSV-2, n = 6), mean 50% inhibitory concentrations (IC50s) for A-5021 were 0.013 and 0.15 microgram/ml, respectively, in MRC-5 cells. Corresponding IC50s for ACV were 0.22 and 0.30 microgram/ml, and those for PCV were 0.84 and 1.5 micrograms/ml, respectively. Against clinical isolates of varicella-zoster virus (VZV, n = 5), mean IC50s for A-5021, ACV, and PCV were 0.77, 5.2, and 14 micrograms/ml, respectively, in human embryonic lung (HEL) cells. A-5021 showed considerably more prolonged antiviral activity than ACV when infected cells were treated for a short time. The selectivity index, the ratio of 50% cytotoxic concentration to IC50, of A-5021 was superior to those of ACV and PCV for HSV-1 and almost comparable for HSV-2 and VZV. In a growth inhibition assay of murine granulocyte-macrophage progenitor cells, A-5021 showed the least inhibitory effect of the three compounds. These results show that A-5021 is a potent and selective antiviral agent against HSV-1, HSV-2, and VZV.

Animals↗
PubMed1998

The relationship between pentosidine and hemodialysis-related connective tissue disorders.

Dialysis-related amyloidosis (DRA), such as destructive spondyloarthropathy (DSA) and carpal tunnel syndrome (CTS), occurs in the connective tissues of patients on long-term hemodialysis (HD). Recently, it was suggested that advanced glycation end products (AGEs) and beta2-microglobulin (beta2m) modified with AGEs are related to DRA. The aim of this study is to elucidate whether serum levels of pentosidine, which is an AGE, relate to the occurrence of DRA in patients with long-term HD. 127 end-stage renal failure patients, with DSA or CTS and undergoing HD, were examined. Serum pentosidine was measured by the HPLC method with column switching. Beta2m and intact parathyroid hormone (i-PTH) were measured. Pentosidine levels were significantly elevated in the DSA, CTS, and DRA groups (patients in the DRA group had either DSA and/or CTS). There were no significant differences in the beta2m and i-PTH levels between any group. The duration of HD did not correlate with either pentosidine or beta2m levels, but did with i-PTH. Receiver-operating characteristic (ROC) analysis was performed to examine the discriminatory ability of pentosidine, beta2m, and i-PTH for DRA. The area under the ROC curve was the greatest for pentosidine. Serum beta2m levels were not related with the occurrence of DRA. The fact that serum pentosidine was higher in DRA than in non-DRA indicates that it has potential as an indicator of the occurrence of DRA in long-term HD patients.

Adult↗
PubMed1998

[Advantages and disadvantages of SMANCS-Lipiodol intrahepatic arterial infusion chemotherapy for unresectable hepatocellular carcinoma].

Though SMANCS-Lipiodol suspension has advantages over tumor regression, its disadvantages should also be considered: (1) Anaphylactic reaction due to its high molecular weight. (2) Since it readily destroys the tissue, a smaller dose and repeated administration are required. (3) Due to its low viscosity, it easily enters the arterioles and causes damage even to the extrahepatic organs. When this drug is infused into the left hepatic artery in subsegmental fashion, it enters the neighboring gastric tissues through the communication of the left hepatic and left gastric arteries, and this ultimately causes intractable gastric ulcers. Considering the above facts, this drug should be used carefully.

Adult↗
PubMed1998

Immunocytochemical differences in adenohypophyseal cells among adult Mongolian pony mares, stallions, and geldings.

OBJECTIVE: To analyze the sex difference in 6 kinds of adenohypophyseal cells of Mongolian ponies and the effect of prepubertal orchidectomy on adenohypophyseal cells. SAMPLE POPULATION: Pituitary glands collected from 15 adult Mongolian ponies, 5 to 10 years old: 5 stallions, 5 mares, and 5 geldings, orchidectomized between the ages of 1 and 2 years. PROCEDURE: Morphologic comparison of 6 kinds of adenohypophyseal cells among mares, stallions, and geldings was done, using immunocytochemistry and morphometry. RESULTS: A sex difference was evident in the percentage of somatotrophs, gonadotrophs (follicle-stimulating hormone [FSH] and luteinizing hormone [LH] cells), and lactotrophs in adult ponies: somatotrophs were more numerous (P = 0.0003) in stallions (approx 40%) than in mares (approx 25%), whereas FSH and LH cells and lactotrophs were more numerous (P = 0.0116, P = 0.0044, P = 0.0085, respectively) in mares (approx 10, 20, and 24%, respectively) than in stallions (approx 6, 15, and 15%, respectively). Prepubertal orchidectomy markedly reduced the proportion of somatotrophs (approx 28%; P = 0.0016) and increased that of lactotrophs (approx 22%; P = 0.0318) in geldings, compared with stallions. The LH cell area was larger in mares than stallions (P < 0.0001). Prepubertal orchidectomy increased FSH (P = 0.0005) and LH (P < 0.0001) cell areas in adult geldings, compared with stallions. CONCLUSIONS: A sex difference exists in adenohypophyseal cells of adult ponies: somatotrophs are more abundant in stallions; FSH and LH cells and lactotrophs are more abundant in mares. Our data indicate that equine testes during postnatal life may stimulate development of GH cells while suppressing development of FSH and LH cells and lactotrophs. The effects of prepubertal orchidectomy on pony somatotrophs and lactotrophs differ greatly from effects on those cells in mice.

Animals↗
PubMed1997

Chemical structure of lipid A from Helicobacter pylori strain 206-1 lipopolysaccharide.

The chemical structure of a novel lipid A, which was obtained as a major component from lipopolysaccharide of Helicobacter pylori strain 206-1, was determined to be a glucosamine beta(1-6) disaccharide 1-(2-aminoethyl)phosphate acylated by (R)-3-hydroxyoctadecanoic acid and (R)-3-(octadecanoyloxy)octadecanoic acid at the 2- and 2'-position, respectively. The absence of a phosphoryl group at the 4'-position and fatty acyl groups at the 3- and 3'-position, and the stoichiometric presence of 2-aminoethyl phosphate at the 1-position are unique features, distinguishing it from the lipid A of enterobacteria.

Carbohydrate Sequence↗
PubMed1997

A case of a pony with Cushing's disease.

The pars intermedia of the pituitary gland, and plasma ACTH and cortisol levels in the pony, which was first diagnosed in Japan as indicating equine Cushing's disease, were examined by immunohistochemistry and radioimmunoassay, respectively. The pars intermedia was greatly enlarged and most of its cells were immunoreactive for antisera to both adenocorticotropic hormone (ACTH) and beta-endorphin (beta-End). The plasma ACTH level was elevated when clinical symptoms appeared. The present results reveal that equine Cushing's disease in this pony was induced by the hypersecretion of ACTH and beta-End from the enlarged pars intermedia of the pituitary gland.

Adrenal Glands↗
PubMed1997

Effect of transportation on the composition of bronchoalveolar lavage fluid obtained from horses.

OBJECTIVE: To study the effects of extended transportation on the composition of bronchoalveolar lavage fluid (BALF) obtained from horses. ANIMALS: 30 horses (14 males, 16 females: 25 Thoroughbreds and 5 Thoroughbred-Arabian cross-breds; 27 to 30 months old) without a history or clinical signs of respiratory tract disease. Bronchoalveolar lavage was performed on nontransported control horses (groups 1 and 2) and transported horses (group 3). PROCEDURE: 20 horses were used to determine the effect of 41 hours of transportation on the composition of BALF (group 3). Bronchoalveolar lavage fluid was analyzed for recovered volume, number and distribution of nucleated cells, total protein and phospholipid concentrations, and phospholipid composition. RESULTS: Total number of nucleated cells in BALF from group-3 horses increased by approximately four-fold after transportation. Total protein concentration in BALF from group-3 horses also increased by approximately fivefold after transportation. Total phosphorus concentrations in group-3 horses decreased significantly from time 0 to immediately after transportation. In group-3 horses, the most characteristic change in composition of BALF after transport was a significant decrease in the concentration of phosphatidylglycerol. CONCLUSION AND CLINICAL RELEVANCE: The decrease in phosphatidylglycerol concentration in BALF after transportation indicates a reduction in the quantity of surfactant. This change may reflect either a decreased production of surfactant by alveolar type II epithelial cells or an increased removal of surfactant from the alveolar region. It is likely that extended transportation resulted in a decreased concentration of surfactant in BALF. Such a decrease may reduce the pulmonary defence mechanisms in the alveolar region, possibly resulting in infection.

Aging↗
PubMed1997

Immunocytochemical localization of adrenocorticotropic hormone-immunoreactive cells of the pars intermedia in thoroughbreds.

OBJECTIVE: To analyze and characterize adenoma and hyperplasia of the pars intermedia (PI) of Thoroughbred mares. ANIMALS: 165 Thoroughbred mares, without clinical signs of hyperadrenocorticism that had been euthanatized or had died, of causes such as sudden death, colic, pneumonia, or trauma, and were necropsied. Five of those horses, 17 to 25 years old, had a large pituitary gland at necropsy. Eight mares, 5 to 15 years old with normal-size pituitary gland, were selected at random for comparison. PROCEDURE: A morphologic comparison of the pituitary gland between horses with and without tumors of the PI was conducted by use of immunocytochemistry and morphometry. RESULTS: In horses with normal pituitary gland, the PI was supplied by a vast capillary or sinusoidal plexus, which connected that in the pars distalis (PD) with that in the pars nervosa (PN). Cells of the PI stained slightly with ACTH antiserum, but some cells in the border region, which is contiguous to the PD, were strongly ACTH immunoreactive. At necrospy, horses with an enlarged pituitary gland also had adenoma of the pituitary gland involving the PI. Cells of the border region were hypertrophied and stained strongly with ACTH antiserum. The area and number of individual tumor cells of the border region of the PI of horses with adenoma were significantly increased, compared with those in horses with normal pituitary gland. CONCLUSIONS: Cells of the PI-PD border region may secrete substantial quantities of ACTH, owing to stimulation by corticotropin-releasing factor. Adenoma and hyperplasia of the PI in Thoroughbred mares may be associated with hyperadrenocorticism.

Adenoma↗
PubMed1996

High concentrations of immunoreactive inhibin in the plasma of mares and fetal gonads during the second half of pregnancy.

Plasma concentrations of immunoreactive (ir)-inhibin were measured in seven pregnant mares from around Day 140 of gestation to Day 2 after parturition using a heterologous bovine-based radioimmunoassay (RIA). Concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), oestradiol-17 beta, progesterone and relaxin were also measured in the same samples. A marked increase in plasma concentrations of ir-inhibin, FSH and LH occurred between Day 220 and Day 300 of gestation but the concentrations of all three hormones returned to baseline by about Day 320 (three weeks before parturition). In contrast, circulating concentrations of the three placental hormones, oestradiol-17 beta, progesterone and relaxin, increased during the final weeks of pregnancy and then decreased markedly to basal values within two days of parturition. There was a positive correlation between circulating concentrations of ir-inhibin and FSH (r = 0.75, P < 0.01) rather than the expected negative correlation. ir-inhibin was not detected in homogenates obtained at Day 190 of pregnancy and form term placenta, but high concentrations of ir-inhibin were present in homogenates of fetal and newborn gonads. Despite the high concentrations of ir-inhibin in these homogenates, they failed to exert any suppressive bioactivity on FSH secretion by rat pituitary cells cultured in vitro. Furthermore, immunohistochemical staining revealed the presence of inhibin in the interstitial cells of equine fetal gonads at Day 190 of gestation. These findings demonstrate for the first time that high concentrations of ir-inhibin, LH and FSH are secreted into the peripheral circulation of the mare during the second half of pregnancy. However, ir-inhibin present in the plasma of pregnant mares appears to be biologically inactive. This hormone is not presumed to be of placental origin but it is proposed that either the enlarged fetal gonads or the maternal ovaries, or both of these organs, may be a source of inhibin in response to the coincident increase in circulating concentrations of LH and FSH.

Animals↗
PubMed1996

Pathomorphological findings in a case of onychomycosis of a racehorse.

The hooves of a racehorse which were affected with white line disease and hoof wall disorders on both forelimbs were histopathologically investigated using thin ground section and standard paraffin section techniques. On both hooves, large quantities of fungus were found to have invaded the white line tissues, especially in the terminal horn which were markedly damaged. The fungus was also present among the cellular debris in the fissures of horny tissues. The morphological characteristics of the fungus were brown (its natural color), PAS-positive, mold-like shape with septa inside the tissues, and unicellular spores outside the tissues. These findings suggest that onychomycosis was a primary and/or secondary cause of white line disease in this subject.

Animals↗
PubMed1996

[Relief of dyspnea after lung volume reduction in patients with pulmonary emphysema].

We studied dyspnea and pulmonary function during treadmill exercise in 10 patients with pulmonary emphysema before and at least 3 months after thoracoscopic volume reduction. Dyspnea was significantly less after surgery. Ventilatory function, gas exchange, respiratory muscle function, and exercise performance also improved significantly. The degree of volume reduction, estimated by the decrease in FRC as measured by body plethysmography correlated with the degree to which dyspnea was relieved. Volume reduction may be appropriate as a treatment for dyspnea in patients with pulmonary emphysema.

Dyspnea↗
PubMed1995

Pathology of equine respiratory disease occurring in association with transport.

Eight young thoroughbred horses, taken 1858 km by road (travelling time, 41 h), were examined to assess the pathological nature of respiratory disease associated with transport. Three of the horses showed clinical abnormalities including pyrexia, coughing, leucocytosis and neutrophilia after the first 20 h of transportation. Endoscopical examination of the trachea revealed exacerbation of airway inflammation as a result of transport in two of the three affected horses. A consistent finding in the affected horses was focal serous neutrophilic pneumonia affecting the cranio-ventral portion of the caudal lung lobe with a propensity to affect the right lung. Streptococcus equi subspecies zooepidemicus was isolated from the pneumonic areas, in which corresponding bacterial antigens were identified immunohistochemically. Viral cultures from the pneumonic lesions proved negative for respiratory viruses. It is suggested that transport predisposes the upper respiratory tract and the lower airways to invasion by the bacterium, with episodic pyrexia and acute pneumonia.

Acute Disease↗
PubMed1995

Age-related morphometrical changes of arteries of uterine wall in mares.

To investigate the morphological changes of uterine wall arteries associated with the progression of age in Thoroughbred broodmares, uterine wall arteries from 13 mares, aged 2 to 31 years, were studied by routine histomorphometry. The ratio of intimal thickness to external diameter increased due to hyperplasia of elastic fibers and was significantly correlated with age (r = 0.95, P < 0.001). The ratio of medial thickness to external diameter decreased and was also significantly correlated with age (r = -0.84, P < 0.001). Using electron microscopy, it was determined that the cross-sectional area of the tunica media occupied by smooth muscle cells gradually decreased with increasing age. These results demonstrate that in arteries of the uterine wall in mares, hyperplasia of intimal elastic fiber and thinning of the medial smooth muscular layer is associated with aging, suggesting that aging may influence endometrial pathology.

Aging↗
PubMed1994

Pathology of equine pneumonia associated with transport and isolation of Streptococcus equi subsp. zooepidemicus.

Seven horses that died of pneumonia associated with transport yielded Streptococcus equi subsp. zooepidemicus (S.z.) from their pulmonary lesions. These lesions were divisible roughly into two types, serous haemorrhagic pneumonia and multiple foci of coagulative necrosis, which were considered to reflect a temporal difference in the process of lesion formation. Immunohistologically, S.z. antigen was detected in both types of lesion. Acute necrotic lacunar tonsillitis was considered to play an important role in the onset of the pneumonia.

Animals↗
PubMed1994

Preparation and characterization of monoclonal antibodies against equine chondrocytes, osteoblasts and osteocytes.

Three monoclonal antibodies capable of individually recognizing chondrocytes, osteoblasts and osteocytes were prepared. EB-1 reacted with a 55-kDa antigen on the chondrocyte membrane, EB-2 with a 110-kDa antigen on the membrane of osteoblasts and/or partial osteocytes, and EB-3 with a 130-kDa antigen on the membrane of osteocytes. These monoclonal antibodies may be useful probes for studying the differentiation and maturation of osteogenic cells.

Animals↗