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Query: UMLS:C0851184 (thinning)
 11,252 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Long-term application up to 8 weeks of a 10% urea solution provokes an epidermal thinning expressed in a decreased number of DNA-synthetizing cells. This epidermal reaction cannot be established after topical use of HTH emulsion. Even by daily application during 8 weeks no change was seen. The absence of epidermal thinning after HTH exposure can be explained as an additive effect of urea and the other constituents of the HTH emulsion. This opinion is supported by the results after application of urea together with Tween 60 in that the acanthogenic effect of Tween 60 is decreased by addition of urea. On the other side, the therapeutic efficiency of 10% 5-fluorouracil solution can be increased remarkably by preliminary treatment with HTH emulsion. These findings could reach importance in the topical therapy with regard to the possibility to improve the effectiveness of any drug by addition of, or preliminary treatment with, urea.
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PMID:[Therapeutical action of urea on the skin (author's transl)]. 89 18

The epidermis thins in response to short-term contact with urea, and the results of extensive enzymological and autoradiographical studies suggest that urea acts on processes involved in epidermal proliferation. After long-term exposure of skin to urea, lasting more than 2, 4, or 6 weeks, no further thinning occurs, and there is no tendency for atrophy to develop during this period. This assertion is made on the basis of biometrical, autoradiographical, and cytophotometrical data. It is likely, however that a reduced number of cells synthesizing DNA is not the only change in normal epidermal proliferation leading to the peidermal thinning that was measured. The urea could also alter factors regulating either cell entry into DNA synthesis or the synthetic process itself, or both. These findings clearly are of significance not only in industrial medicine but also in the use of urea in topical dermatological therapy.
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PMID:[Reaction of epidermis after long-term action of urea]. 122 52

As a reaction of the epidermis subsequent upon contact with urea, a thinning is ascertainable 5 days later, for which corresponding enzymological and autoradiographical findings cause to presume the DNA being the working point. Further information about the mechanism of this reaction was obtained first by short time tests, whence by means of 3H thymidine autoradiography not later than the second day after contact with urea a decreased number of cells synthesizing DNA in the stratum basale were to be secured. These findings obtained using the model of the guinea-pig's ear are also ascertainable in the human skin, an unspecified effect, also to be released by other non-electrolytes, having been excluded by controls of glucose replacing urea. The quick invasion of urea into the epidermis, deducible from the short time tests, was proved by 14C traced urea, ascertainable not later than 15 min after its contact with the skin amongst the blood - even if in little activity. Hence, the urea enters into the cutis speedily, releasing there a disturbance in the process of the epidermal proliferation, which conducts in the sequel to an epidermal thinning.
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PMID:[Investigations on the mechanism of the activity of urea upon the epidermis (author's transl)]. 125 64

We showed previously that the proliferation of hamster airway secretory cells decreases during vitamin A deficiency (VAD) but later increases when submucosal inflammation develops (Virchows Arch [B] 59:231-242, 1990). This observation has important biological implications since two morphological extremes (atrophy and quiescence versus hyperplasia and hyperproliferation) are reported in the literature for VAD tracheal epithelium in vivo. In the present study, histological slides of tracheal rings from 35-day-old control and VAD hamsters (Virchows Arch [B] 45:197-219, 1984) were reviewed again. Rings from VAD hamsters were selected based on the absence or presence of a florid submucosal inflammation. Quantitative analyses were made on the cartilaginous part of rings from the anterior third of the trachea. When inflammation was absent, a mucociliary pseudostratified epithelium was, for the most part, maintained. The mitotic rate (MR, 6 h colchicine blockade) of secretory cells was markedly reduced (29-fold) but that of basal cells was not changed significantly. Moreover, cell density was not changed by VAD but ciliated cells and secretory cells were decreased and basal cells were increased, proportionally. We call this "minimal morphological change." Thinning (atrophy) of the minimally changed epithelium was associated with focal cell sloughing. Small scattered foci of epidermoid metaplasia (multiple layers of highly keratinized cells which were extremely flat, so that the epithelium was thin and attenuated) were also seen. We call this "atrophic epidermoid metaplasia." When inflammation was present, hyperplastic changes (stratification and epidermoid metaplasia) predominated and cells were in mitosis at all epithelial levels (low, middle, superficial) except in the most superficial (terminally differentiated) squames. The tracheal epithelium was thickened and hypercellular. The cells were piled up at the stratified lesions, and epithelial height, cell density and epithelial MR were significantly increased compared with the non-inflamed VAD epithelium. The effects of VAD and inflammation on cell proliferation were analyzed further by studying 7 h bromodeoxyuridine (BrdU) labelling patterns of cells in VAD tracheal epithelium, with and without submucosal inflammation. In addition, inflammation was induced in "minimally changed epithelium" by mild mechanical injury. The BrdU labelling patterns confirmed that DNA synthesis by secretory cells is reduced markedly by VAD. However, this suppression is overidden by the influx of inflammatory cells (the nature of the stimulus is unknown). The results indicate that the morphological contrasts (atrophy and hyperplasia) seen in the trachea during VAD in vivo are related to extremes in proliferation rates of tracheal secretory cells, regulated by VAD alone (minimal replication) and by inflammation (maximal replication).
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PMID:Vitamin A deficiency and inflammation: the pivotal role of secretory cells in the development of atrophic, hyperplastic and metaplastic change in the tracheal epithelium in vivo. 134 77

We have analyzed the effect of extracellular stimuli on the differentiation state of the CA77 thyroid C-cell line as a model to understand the control of neural crest cell differentiation. In contrast to the endocrine C-cell phenotype, we found that CA77 cells have a neuronal phenotype characterized by laminin-induced neurites, neuronal antigens, and calcitonin gene-related peptide (CGRP) mRNA expression. Treatment with dexamethasone and retinoic acid reversibly repressed some of these neuronal characteristics to induce features more characteristic of the parental C-cells. In the case of dexamethasone treatment, there was a partial retraction and thinning of neurites, an increased number of secretory vesicles in the cell bodies, and about a 10-fold decrease in DNA synthesis. Treatment with retinoic acid alone or in combination with dexamethasone caused decreased cell adhesion and an even more extensive retraction of the neurites. Dexamethasone also biased the steady state levels of the alternatively spliced transcripts from the calcitonin/CGRP gene to favor calcitonin relative to CGRP mRNA. While retinoic acid treatment decreased both calcitonin and CGRP mRNA levels, the combination of dexamethasone and retinoic acid still yielded the increase in calcitonin relative to CGRP mRNA. These results suggest that glucocorticoids and retinoic acid may contribute to a late and reversible differentiation of thyroid C-cells by partly repressing neuronal properties.
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PMID:Neuronal properties of a thyroid C-cell line: partial repression by dexamethasone and retinoic acid. 156 64

The hairless mouse has been used as a model to distinguish between local and systemic atrophogenic effects of topical steroids. Hydrocortisone-17-butyrate, betamethasone-17-valerate, budesonide and clobetasol-17-propionate were applied topically daily for 21 days. Skinfold thickness and dermal DNA synthesis of treated and untreated skin were evaluated as parameters of local and systemic atrophogenicity. Further, body weight gain and thymus weight were assessed as markers of systemic activity. With respect to local effects, skin thickness and dermal DNA synthesis both proved to be good parameters. Of the systemic parameters, thymic involution and body weight gain paralleled quite well the skin thinning on the untreated side. The results confirmed the potency differences of the steroids. Furthermore, they emphasize the usefulness of the hairless mouse to assess the relative safety with respect to local and systemic side effects of chronically applied topical corticosteroids.
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PMID:The hairless mouse as a model for study of local and systemic atrophogenic effects following topical application of corticosteroids. 167 10

The safety and efficacy of 1% dextran in Chondroitin Sulfate Corneal Storage Medium (CSM) in reducing corneal swelling after 4 degrees C storage was assessed in a corneal endothelial cell culture system. No difference was found in 3H-thymidine incorporation by cells incubated in either CSM-dextran medium or CSM medium alone. Subsequently, 21 pairs of corneas, stored in either CSM or CSM-dextran from 30 to 112 hours, were transplanted into 42 eyes of 42 patients, paired by diagnostic group and procedure. All CSM grafts and 19 of 21 CSM-dextran grafts were clear at 4 months with no primary donor failures in either group. Intraoperative corneal thickness was significantly greater in the CSM group (0.82 +/- 0.07 mm) than the CSM-dextran group (0.76 +/- 0.06 mm); however, the two groups did not differ thereafter. No differences in all endothelial morphometric parameters were noted between the two groups pre- and postoperatively. Average endothelial cell loss by 4 months was 13.0 +/- 16.4% for the CSM group and 16.4 +/- 15.5% for the CSM-dextran group. The addition of dextran to CSM medium results in significant intraoperative corneal thinning without adversely affecting endothelial DNA synthesis in vitro and endothelial survival in vivo.
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PMID:An in vitro and clinical comparison of corneal storage with chondroitin sulfate corneal storage medium with and without dextran. 169 Mar 74

Growth plate cartilage from normal and vitamin D-phosphate deficient (-VDP) rats was cultured to study the production of collagenase and tissue inhibitor of metalloproteinases (TIMP) in vitro. All tissues secreted latent collagenase into the medium at a constant rate during the 5 days in culture. Microdissected-VDP growth plates, containing predominatly hypertrophic cells, released up to 8-fold more collagenase into the medium than either intact-VDP or normal growth plates. TIMP was also secreted during the culture, but its rate of production was not as dependent on tissue type as collagenase. The tissue level of collagenase and TIMP before culture was compared with that found in conditioned medium and remnant tissue after culture. During the 5 day culture period microdissected-VDP growth plates, containing predominatly hypertrophic cells, produced 3-times more collagenase/microgram DNA over the starting level than either intact-VDP or normal growth plates. TIMP was never found in tissues after they had been cultured, but was present in all tissues before culture except those containing predominatly hypertrophic cells. The amount of TIMP required to block collagenase was calculated. Growth plates in culture produced enough TIMP to block all collagenase found in the medium and remnant tissue, while extracts of uncultured intact -VDP growth plates, and those divided to contain hypertrophic cells, had an excess of collagenase over TIMP. The results suggest that hypertrophic cells produce far more collagenase than other cells in the growth plate, but all cell types have about the same capacity to synthesize TIMP. As a result, increased collagenase synthesis by hypertrophic cells may surpass increases in TIMP synthesis and lead to collagen removal. This would allow for thinning of the longitudinal septa and expansion of the hypertrophic cells.
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PMID:Production of collagenase and tissue inhibitor of metalloproteinases (TIMP) by rat growth plates in culture. 196 14

Late-onset cerebellar degeneration can be induced transplacentally in mice by a single low-dose (1 mg/kg) injection of the direct-acting DNA alkylating agent N-methyl-N-nitrosourea (MNU) on day 16 of pregnancy. The offspring develop a mild ataxia that manifests by 12-16 weeks of age postnatally when the animals are challenged with a motor coordination task. Morphological evidence of degeneration includes pyknosis of Purkinje cells and abnormal foliation patterns. Additionally, these animals demonstrate a progressive retinopathy characterized by thinning of the nuclear and plexiform layers of the retina. Efforts to retard the cerebellar degeneration were undertaken in the present study. MNU-exposed and control animals were fed a standard mouse chow diet supplemented with 0.75% butylated hydroxytoluene (BHT), an antioxidant. This supplementation commenced 24 h following exposure to the teratogen and continued throughout the life of the offspring. A second group of MNU-exposed and control mice were fed a non-BHT-supplemented, standard Purina mouse chow diet. Quantitative histological evaluation of cerebellar coronal sections indicated that by 4 weeks of age BHT-fed, MNU-exposed mice had significantly fewer pyknotic Purkinje cells than non-BHT-fed, MNU-exposed animals. This was true for the vermal, paravermal, and lateral areas of the cerebellum. The findings suggest the usefulness of teratogenic models of degenerative diseases for the testing of potential intervention strategies.
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PMID:The antioxidant butylated hydroxytoluene can retard cerebellar degeneration induced transplacentally by a single low dosage of N-methyl-N-nitrosourea. 256 66

In this study, the antiproliferative activity of a 0.05% alclometasone ointment (Alc, Delonal) on the epidermis of the mouse tail was investigated. We have found that Alc thins the epidermis to approximately the same extent as hydrocortisone acetate (1%), but has an extremely slighter epidermal thinning effect than betamethasone (betametasone-17,21-dipropionate, 0.064%, Diprosis). The incorporation rate of 3H-thymidine triphosphate into the DNA was inhibited to almost the same extent. In conclusion the small antiproliferative effect of Alc shows no correlating effects compared with its high vasoconstrictory efficacy.
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PMID:Comparative investigation of the antiproliferative efficacy of alclometasone. 275 36


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