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

Theophylline (1 mM) produced a net transport of Na and Cl from aqueous humor to tears (.02-.04 mumol/cm2 h) in the isolated rabbit cornea denuded of endothlium and in the presence of normal resting potential (25-35 mV). The active transport of Na (tears to aqueous) and of Cl (aqueous to tears), estimated with the Goldman constant-field equations, was confirmed. A 10 degrees C rise in temperature produced changes close to those predicted for passive processes in both unidirectional fluxes of Na and in the tears-to-aqueous flux of Cl, but not for the aqueous-to-tears flux of Cl. Theophylline treatment doubled Cl permeability but did not significantly affect Na or urea permeability, suggestingspecificity of affect. In separate experiments it was shown that stromal thinning occurred in previously swollen corneas when the endothelium was blocked by silicone oil and the epithelium was treated with theophylline. These findings provide further support for the argument that the mammalian epithelium could have an active role in the regulation of corneal thickness in situ.
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PMID:Transport of Na, Cl, and water by the rabbit corneal epithelium at resting potential. 16 32

If urea, a physiologic substance, is applied locally, it has a favorable effect on the skin, it keeps the horny layer moist. However, high concentrations might impair the functions of the skin, for urea penetrates easily into the skin, exerts mucolytic and keratolytic effects, changes the keratin structure, and promotes just like dimethylsulfoxide, the permeation and the resorption of active ingredients. Moreover, urea causes a thinning of the epidermis by influencing the epidermal prolifertion. The properties of urea are of considerable interest in dermatotherapy. However, high concentrations of urea should only be applied for long periods of time, and on large surfaces of the skin, for instance in the treatment of dry skin, in the form of cosmetics, under medical supervision.
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PMID:[Urea : properties, effects, use]. 86 89

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

Intestinal absorption and intraluminal pressures were measured at perfusion rates between 0.3 and 200 ml per min in the rat ileum in vivo. Glucose absorption from a 72 mM glucose solution and tritiated water ([3-H]water) diffusion rate were used to reflect changes in mucosal surface area. Glucose absorption from a 4 mM solution was used to indicate changes in unstirred water layer thickness, and mannitol and urea absorption were used as markers of passive mucosal permeability. In a partially obstructed intestinal segment, designed to keep the gut partially filled even at low perfusion rates and to minimize surface area change as perfusion rate was increased, glucose absorption from a 4 mM solution increased by 150% as perfusion rate was increased from 1 to 100 ml per min. Forty per cent of this increase was due to increased surface area (estimated from the change in [3-H]water absorption), and 110% of the increase is attributed to thinning of the unstirred water layer. Because mannitol absorption was zero at all perfusion rates, none of the enhanced glucose absorption rate need be attributed to enhanced mucosal permeability, even though intraluminal pressure was increased at higher perfusion rates. Urea absorption was apparently influenced by surface area and by permeability changes, but not by the thickness of the unstirred water layer. This model was also used to explore the effect of unstirred water layer thickness on the inhibitory effect of sodium replacement by magnesium on glucose absorption from a 4 mM glucose solution. Inhibition by sodium removal was equal at 1, 10, 100, and 200 ml per min perfusion rates, suggesting that unstirred water layer thickness does not play an important role in the interaction of glucose and sodium absorption when intraluminal sodium concentration is reduced. Additional experiments in an unobstructed ileal segment revealed that the major effect of enhanced perfusion rate is to increase mucosal surface area; relatively high rates of perfusion were required to thin significantly the unstirred water layer when intestinal outflow was not partially obstructed.
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PMID:Effect of perfusion rate on absorption, surface area, unstirred water layer thickness, permeability, and intraluminal pressure in the rat ileum in vivo. 113 32

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

A clinical trial has been conducted to assess the efficacy of 1% bifonazole and 40% urea ointment for 2 weeks followed by 1% bifonazole cream for one month in the topical treatment of onychomycosis. Thinning and total avulsion of the nails occurred in 97% of 30 patients with candidal onychomycosis and regrowth of a normal appearing nail was found in 92% of 26 patients. Failure rate was 4% and recurrence rate was 12% in 26 patients. Results of the treatment was followed up for 12 weeks. Side effects were negligible.
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PMID:Treatment of onychomycosis with a bifonazole-urea combination. 214 98

Due to keratolytic and epidermis-thinning effects 10% urea/w/o is effective in the treatment of papillomatosis cutis verrucosa (lymphostatic papillomatosis). If possible, compression bandages should be used. Indirect lymphography reveals abnormalities of dermal lymphdrainage in papillomatosis cutis verrucosa.
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PMID:[Treatment success using topical drugs containing urea in papillomatosis cutis verrucosa (lymphostatic edema papillomatosis)]. 280 31

Chronic, rapid ventricular pacing produces congestive heart failure in the dog. Using echocardiography, the features of developing heart failure were analysed and the capacity of this model for recovery was assessed once pacing had been discontinued. Fifteen dogs were studied; nine were paced at 250 beats/min (bpm) to severe heart failure (5.0 +/- 1.8 weeks) and six served as sham controls. In the paced animals at severe heart failure, two-dimensional echocardiography demonstrated a significant increase in diastolic cross-sectional cardiac area (from 11 +/- 3 to 16 +/- 2 cm2, p less than 0.05), associated with a marked fall n area ejection fraction (54 +/- 8 to 21 +/- 8%, p less than 0.05), and significant left ventricular wall thinning (from 6.0 +/- 0.7 to 4.7 +/- 0.9 mm, p less than 0.05). In addition, significant increases in heart rate (77 +/- 7 to 126 +/- 13 bpm, sinus rhythm; p less than 0.05), respiratory rate (41 +/- 13 to 80 +/- 20 cycles/min, p less than 0.05), and body weight (21 +/- 1 to 24 +/- 3 kg, p less than 0.05) were noted. Serum sodium fell (146 +/- 3 to 140 +/- 8 mmol/L, p less than 0.05), while blood urea nitrogen (6 +/- 2 to 10 +/- 2 mmol/L, p less than 0.05) and creatinine (86 +/- 12 to 101 +/- 15 mmol/d, p less than 0.05) increased. Recovery was characterized by rapid improvement such that all measured parameters normalized by 1 week, except for cross-sectional cardiac area which remained dilated up to 4 weeks (14 +/- 3 cm2, p less than 0.05 versus control).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Recovery from heart failure: structural and functional analysis in a canine model. 322 85

Renal physiological and morphological adjustments to a reduced protein diet were studied in young Munich-Wistar rats. Two groups of animals were used for the correlative physiological-morphological studies: normal protein (NP, 24% dietary protein) rats and reduced protein (LP, 8% dietary protein) rats. Both groups were fed their respective diets for 4-5 wk and had free access to drinking water. Physiological measurements of GFR and urea clearance were made on five animals from each group. These data showed that the changes in renal function specifically and almost exclusively affected the handling of urea. There was no difference in GFR between the NP and LP rats. Urea clearance was substantially reduced in LP rats. Morphological analyses were made on perfusion-fixed kidneys of five animals from each group. Selected slices were examined and photographed by light and electron microscopy. These data showed no difference in size and number of elements within the vascular bundles but showed significantly smaller lumina of the thin limbs of the short-looped nephrons and a significant thinning of the wall of the thin descending limbs of the long-looped nephrons. These morphological changes may in part be responsible for the observed physiological adjustments to a reduced protein diet. An additional group of rats (6 NP and 5 LP, all dehydrated) were analyzed for distribution of solutes within the inner medulla. The data showed that the concentration of urea, but not that of Na+, was reduced at the papillary tip in LP rats.
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PMID:Physiological and morphological responses of the rat kidney to reduced dietary protein. 397 Jan 63


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