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Biomedical subjects

D Lewinson

Publications and source records attributed to D Lewinson.

45 records · Page 3Linked to original sources
PubMed1981

Glucocorticoid-induced changes in the activity of cartilage alkaline phosphatase.

Glucocorticoid hormones are known to exert distinct inhibitory effects upon cartilage metabolism and endochondral bone growth. This study examined the influence of triamcinolone hexacetonide, a long-acting synthetic analogue off cortisol, on the activity of non-specific alkaline phosphatase i condylar cartilage of neonatal mice. Four-day-old mice received a single dose (10 mg/kg) of the hormone and the activity of beta-glycerophosphatase was assayed 3 and 6 days thereafter. Whereas no significant changes were noted in the enzyme's specific activity, distinct alterations were observed in the latter's distributional pattern. By 48 hours cells along both the proliferative and chondroblastic zones exhibited a significant enhancement of alkaline phosphatase activity. This increase in enzyme activity was most prominent along the cells' plasmalemma and within their adjacent matrix. Thus, glucocorticoid hormones possess a significant stimulatory effect upon alkaline phosphatase activity in very young cartilage cells which in turn might affect the mineralization process.

Alkaline Phosphatase↗
PubMed1980

Combined effect of calcitonin and glucocorticoid hormone on calcium content of cultured bone cells.

The combined effect of calcitonin and triamcinolone acetonide on Ca2+ content in cultured bone cells was studied. Cultures were first preincubated with 45Ca for 24 hrs thus achieving a steady state between the extracellular and intracellular 45Ca2+. Calcitonin was added for 24 hrs and subsequently, triamcinolone acetonide was added for time intervals ranging from 1 to 24 hrs. Calcitonin induced a significant increase in the content of cellular exchangeable Ca2+. When triamcinolone was added to cultures pretreated with calcitonin a marked efflux activity was noted. Concomitant ultrastructural histochemical examinations, using the K-pyroenthymonate fixation method, further substantiated the above finding: calcitonin treated cells revealed increased number of Ca-pyroenthymonate precipitates, whereas the combined treatment led to the disappearance of such Ca-aggregates.

Animals↗
PubMed1978

Glucocorticoid-induced alterations in collagen of neonatal mouse condylar cartilage.

Neonatal mice were treated with a single dose of triamcinolone hexacetonide, a long-acting synthetic analogue of cortisol, and their mandibular condyles were studied ultrastructurally ten days thereafter. A pronounced decrease in the number and size of matrix granules (proteoglycans) was found in the cartilaginous matrix of triamcinolone-treated condyles. In contrast, a marked increase concomitant with significant structural changes was noted in collagen fibrils. An obvious enhancement of collagen fibrillogenesis was noticed in the pre-mineralizing extracellular matrix. Atypical, wider than normal, banded collagen fibrils were found to form dense meshworks which appeared to lack any specific orientation or organization. It is proposed that glucocorticoid hormones, given systemically to neonatal mice, interfere with regulatory mechanisms involved with the biosynthesis of cartilaginous matrical macromolecules, i.e., proteoglycans and collagen and thereby promote certain aging processes within active growth centers.

Animals↗
PubMed1978

An electron microscopic study of the premineralizing zone of the condylar cartilage of the mouse mandible.

The mandibular condylar cartilage of young ICR mice was used for ultrastructural studies with special emphasis on the cells and matrix in the premineralizing zone. It became evident that cytodifferentiation of chondroblasts was accompanied by deposition of intracellular lakes of glycogen, followed within the premineralizing hypertrophic chondrocytes by a gradual reduction in the glycogen content of the lakes and its replacement by lipid-like droplets. The premineralizing condylar cartilage, like that of other cartilage involved in mineralization, showed numerous matrix vesicles (Types I and II) unassociated with appreciable amounts of collagen.

Animals↗
PubMed1977

Ultrastructure of epidermis of Salamandra salamandra followed throughout ontogenesis.

Ventral epidermal ultrastructure of the amphibian urodele Salamandra salamandra is described and followed throughout its life cycle. Tadpoles were divided into five categories on the basis of the organization of their epidermis and the ultrastructure of its cells. In newly hatched tadpoles the epidermis is arranged in two layers and four types of cells were recognized. The number of epidermal layers increases in the metamorphosing tadpole. At this stage the layers become organized in four strata. Metamorphosis involves the disappearance of some cell types and the appearance of others, typical of the adult epidermis. The significance of these ontogenetic changes in epidermal ultrastructure is discussed in respect to aquatic and terrestrial life habits.

Animals↗
PubMedDate not supplied

Corticosteroid-induced enhanced mineralization in neonatal condylar cartilage.

Neonatal mice were treated with triamcinolone hexacetonide and the cartilage of their mandibular condyle was studied biochemically and histochemically. Three days following the hormonal treatment the condylar protein content decreased significantly but a marked increase was noted in the tissue's calcium and phosphate. The condylar mineralization front extended up to the chondroblastic and proliferative zones. Triamcinolone arrest cartilage cell proliferation and enhanced an atypical hypertrophy of chondroblasts. One week following the hormonal treatment the condyle revealed clear signs of weight loss and changes in its size and form. Glucocorticoids enhance the mineralization of neonatal cartilage via: a direct effect upon chondrocytic metabolic and control systems (genom) and possibly also through an indirect adverse effect upon other organ systems.

Animals↗
PubMedDate not supplied

[Haemophilus influenzae B meningitis and Waterhouse-Friderichsen syndrome in a 5-month-old infant].

A five months old infant with Waterhouse-Friderichsen syndrome related to Haemophilus influenzae type b meningitis is reported. In spite of treatment with IV fluids, antibiotics and dopamine, he died eight hours after admission. Necropsy findings included bilateral adrenal bleeding compatible with the Waterhouse-Friderichsen syndrome. This is the younger infant reported with this diagnosis in association with Haemophilus influenzae in Chile.

Humans↗