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Biomedical subjects

K Otsuka

Publications and source records attributed to K Otsuka.

At least 325 records · Page 18Linked to original sources
PubMed1984

Biosynthesis of osteonectin by fetal porcine calvarial cells in vitro.

The biosynthesis of osteonectin, a major glycoprotein of bone, has been studied in vitro using bone cells from fetal porcine calvariae. The calvarial cells, which were shown to produce osteonectin by immunotransfer and immunocytochemical analysis, were pulse labeled with [35S]methionine and the radiolabeled osteonectin in the cell layers and in the chase-medium was isolated by specific immunoprecipitation. The osteonectin, representing 0.1% of the radiolabeled cell layer and 1% of the medium proteins, co-migrated with authentic bovine osteonectin on sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reduced and nonreduced conditions (Mr approximately 40,000), and was bound selectively to hydroxyapatite in the presence of 4 M guanidine HCl. The co-migration of the osteonectins indicates that the tissue-extracted osteonectin represents an intact protein and that a pro- form of osteonectin is unlikely. However, a preosteonectin form (Mr approximately 46,000) could be immunoprecipitated from cell-free translation of calvarial mRNA. The minimal secretion time for osteonectin synthesized in serum-containing medium was found to be approximately 40 min but maximal accumulation did not occur until 2 h postlabeling. In serum-free media, extensive degradation of osteonectin, characterized by the presence of two immunoprecipitable fragments (Mr approximately 36,000 and 31,000), was evident.

Animals↗
PubMed1984

Collagenase synthesis by osteoblast-like cells.

Cultures of osteoblast-like cells from a rat sarcoma and osteoblast-enriched populations of rat calvarial cells synthesize and secrete a true collagenase and collagenase inhibitor. The enzyme, which is produced in a latent form, appears to be similar to the enzyme produced by fibroblasts.

Animals↗
PubMed1984

Myospherulosis of the mandible. Report of a case and review of the literature.

A case of myospherulosis in a 67-year-old female is reported. The lesion appeared as a submucosal mass firmly attached to the buccal periosteum of the right molar region of the mandible. Although the records of our case did not specify what medication was placed in the lesion, clinicopathologic features further supported the hypothesis that myospherulosis may be a unique instance of iatrogenic disease caused by petrolatum-based antibiotic ointments.

Aged↗
PubMed1984

Change in phenotype in long-term cultures of a clonal rat bone cell line: switch to the synthesis of alpha 1(I)-trimer collagen.

A number of bone cell clones isolated from rat calvaria have been maintained in culture for more than 3 years. Several of these clones have undergone dramatic changes in phenotype. One of these clones, RCB 2.2, was observed originally to have a fibroblastic morphology in culture and to respond to parathyroid hormone (PTH), but not prostaglandin E2 (PGE2), with an increase in intracellular cAMP. Throughout several passages in early subcultures, these cells synthesized mostly type I collagen, with small amounts of type III and type V collagens. Whereas PTH had no detectable effect on collagen synthesis, PGE2 decreased the amount of total cell layer collagen, with the greatest effect on type III collagen, while increasing the proportion of type V collagen. Subsequent studies on these cells during 3 years in culture have indicated changes in their phenotype including a progressive change in morphology to a more cuboidal shape and a change in collagen synthesis, the cells producing large amounts of the "embryonic" collagen, alpha 1(I) trimer. The reason(s) for the change in collagen expression is unknown, but may be the result of a change in which gene(s) is being expressed.

Animals↗
PubMed1984

An osteonectinlike protein in porcine periodontal ligament and its synthesis by periodontal ligament fibroblasts.

Periodontal ligament, a soft connective tissue that lies between cementum and alveolar bone in the periodontium, has been shown to contain an osteonectinlike protein. The similarity between porcine ligament osteonectin and bovine bone osteonectin was evident from immunochemical studies, from migration characteristics on sodium dodecyl sulfate - polyacrylamide gel electrophoresis (SDS-PAGE) and from binding studies on hydroxyapatite. Using immunotransfer and immunodot analyses, ligament osteonectin was found to be extractable from tissues with 4 M guanidine-HCl (GuHCl) and 4 M GuHCl - 0.5 M EDTA and to comigrate with authentic bovine osteonectin on SDS-PAGE with a relative mass approximately 38 000. Furthermore, osteonectin from guanidine extracts of ligament was bound to hydroxyapatite in the presence of 4 M GuHCl. Immunofluorescence studies showed the osteonectin to be distributed throughout the extracellular matrix of the ligament and to be present within the ligament fibroblasts in a perinuclear, punctate distribution. Biosynthesis of osteonectin by ligament fibroblasts was studied following pulse-chase labelling with [35S]methionine and immunoprecipitation. The labelled osteonectin in the chased culture medium represented approximately 0.5% of the total labelled proteins secreted. It comigrated on SDS-PAGE with the corresponding labelled protein from pulsed cells and with the protein extracted from the tissue.

Animals↗
PubMed1984

Effect of pindolol and nifedipine alone and in combination on haemodynamic parameters/variables in essential hypertension.

Thirteen patients with essential hypertension were started on pindolol 10-20 mg daily and twelve on nifedipine 20-60 mg daily. At the end of 6 weeks inadequate responders (B.P. greater than 140/90) were put onto combined treatment with both drugs, ten of the pindolol and six of the nifedipine patients being affected. Combined therapy then continued for a further 6-week period, while adequate responders (B.P. less than 140/90) continued with their initial drug. In addition to blood pressure, heart rate and cardiac index were also measured, and total peripheral resistance index was calculated. Where blood pressure decreased below 140/90 at the end of 12 weeks in patients on combined treatment, the original drug was withdrawn, leaving the patient on a single-drug regimen again, this time with the 'second compound'. This manoeuvre was followed by a rise in blood pressure in five out of eight patients in whom pindolol was withdrawn and in two out of six after nifedipine withdrawal. No definite conclusions can be drawn from these findings, and it may be that a better approach to the problem of poor responders would be to try each drug on its own before combining them, rather than combining first and then withdrawing the initial treatment. The increased peripheral resistance typical of essential hypertension was not adversely affected by either drug, while combined treatment had a beneficial effect on this parameter.

Adult↗
PubMed1983

Effects of estrogen on the excitability of neurons projecting from the noradrenergic A1 region to the preoptic and anterior hypothalamic area.

Estradiol benzoate administered to ovariectomized female rats significantly elevated the mean spontaneous firing rate and frequency of successful antidromic propagation into the somatodendritic spike and significantly reduced the strength of post-stimulus inhibition in presumed A1 noradrenergic neurons projecting directly to the preoptic and anterior hypothalamic area. The occurrence of both antidromic spikes and post-stimulus inhibition of the majority of these neurons was completely abolished by the injection of 6-hydroxydopamine but not by 5, 7-dihydroxytryptamine directly into the medial forebrain bundle.

5,7-Dihydroxytryptamine↗