Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0033774 (pruritus)
 14,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Weaned hairless rats were fed a diet deficient in fat, magnesium and folacin. After approximately 1 week, an erythematous dermatitis developed which was associated with extreme generalized pruritus. Scratching led to excoriations and hemorrhagic crusting. The acute stage (pruritic rash) resolved after several days and was followed by sporadic non-itching relapses. Subsequent to the onset of symptoms, rats were treated orally, once daily for 3 days with CyA, CyH or FK506. The immunosuppressants CyA and FK506 caused a dose-dependent inhibition of symptoms in contrast to CyH. The immediate clinical response was associated with changes in blood histamine, white blood cell counts and histological parameters. Since CyH is known to lack immunosuppressive activity, these results may indicate that the cutaneous changes induced by the nutritional deficiency are associated with immunological abnormalities. The results may also indicate mechanisms influenced by CyA and FK506 but not by CyH; for example, release of chemical mediators from inflammatory cells.
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PMID:Diet-induced dermatitis response of hairless rats to systemic treatment with cyclosporin A (Sandimmun), cyclosporin H and FK506. 128 11

Postburn hypertrophic scars on the pubic area are rare. A local iliac flap has been used in four female patients for covering the raw areas after total excision of these scars. The largest flap in this series was 7 x 13 cm. Although bilateral flaps could be used simultaneously, only a unilateral flap was used in each patient. All the donor sites were closed primarily. The postoperative course was uneventful in each patient. Itching subsided completely in all patients and distortions of the genitalia were corrected. There was no recurrence of the scar formation in the follow-up period from 2 to 7 years. The only drawback of this flap for coverage of the symphysis pubis is that it is hairless. The experience with the present patients proved that this is an easy, quick and reliable method for removing hypertrophic scars on the pubic area.
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PMID:Management of hypertrophic scars on the pubic area with an iliac flap. 189 55

An animal experiment is presented in which three groups of albino hairless mice (Skh-hr 1) were exposed to daily doses of either UV-B or UV-A to study carcinogenesis. The UV-A was filtered carefully so as to eliminate contaminating UV-B. The doses required for acute effects (erythema and edema) were also determined for the two radiation modalities. In order to study the relative carcinogenic risks of exposures to UV-A and to UV-B, for both modalities, the doses causing skin tumors were compared to the doses required for eliciting acute effects in the skin. In the experiment on carcinogenesis all animals developed tumors, the ones exposed to UV-A as well as the ones exposed to UV-B. A striking difference, however, was that the induction times of the first tumors showed a larger spread in the mice exposed to UV-A than in the UV-B groups. Also, the development of successive tumors in each individual mouse was more spread in time in the UV-A group. A second difference between the effects on the skin was that in the animals exposed to UV-B no skin reactions were seen until the tumors developed. However, in most UV-A exposed animals, a marked scratching, probably caused by severe itching, and hyperkeratosis preceded the development of the tumors. Histologically at least 60% of the larger tumors induced by UV-A appeared to be squamous cell carcinomas. This finding is very similar for UV-B induced tumors. The elastic fibers in the UV-A exposed animals were also examined and actinic elastosis was observed.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The carcinogenic risks of modern tanning equipment: is UV-A safer than UV-B? 317 87

Exposure of anthracene treated skin to long-wave ultraviolet radiation (UVA) will produce hyperemia, increased vascular permeability, burning and itching. This photosensitized inflammation was produced in the skin of hairless mice by the topical application of a 0.025% (w/v) solution of anthracene followed by exposure to UVA. The resultant hyperemia was quantified by the increase in 51Cr-erythrocyte content (cpm/wet weight) of skin. After 1000 sec (1.3 x 10(4)J/M2) of UVA, the blood content of the skin had increased nine-fold. Pyrilamine (H1 antagonist), administered orally, did not inhibit the hyperemia in response to anthracene-UVA, whereas cimetidine (H2 antagonist) increased the blood content of the skin. However, a combination of pyrilamine and cimetidine significantly inhibited the hyperemia, indicating that histamine may mediate the anthracene-UVA hyperemia via H1 and H2 receptors on dermal vessels. Since neither antagonist alone blocked the response, the mechanism of histamine action in this response may involve histamine receptors on other dermal components in addition to the blood vessels. In particular, the exacerbation of this photosensitized inflammation by cimetidine lends support to the concept of H2 receptors on mast cells which negatively modulate histamine release.
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PMID:Quantitation of phototoxic hyperemia and permeability to protein: II. Inhibition by histamine (H1 and H2) receptor antagonists in mouse skin. 743 Jul 9

The studies described herein characterize animal behavioral models for conjunctival and cutaneous itch. Histamine was used as the reference stimulus for model development because it is firmly established as a pruritogen in both conjunctiva and skin. Itching evokes the desire to scratch in human subjects, so hind limb scratching at the afflicted area was used to identify pruritogenic stimuli. Under optimized environmental conditions, hind limb scratching behavior yielded substantial and highly reproducible responses. The conjunctival itch-scratch response was delineated from pain and foreign body sensations by using appropriate stimuli. Examination of a large and diverse variety of autocoids revealed that only histamine, platelet-activating factor (PAF) and arachidonic acid and its cyclooxygenase metabolite prostaglandin E2 possessed meaningful pruritogenic activity. PAF-induced ocular pruritus did not involve histamine release, according to studies with appropriate antagonists. Thus PAF-induced ocular pruritus was unaffected by the histamine H1-receptor antagonist pyrilamine but was substantially attenuated by the PAF antagonists WEB 2086 and CV-6209 and was virtually abolished by E-6123. Similar itch-scratch behaviors were quantified in hairless guinea pig skin following the application of cowhage or the iontophoretic administration of histamine and PAF. Findings from these newly developed itching models suggest that PAF could be an important mediator of the pruritic sensation by activating a population of nerve endings responsible for encoding the itch sensation.
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PMID:Characterization of a behavioral model for peripherally evoked itch suggests platelet-activating factor as a potent pruritogen. 785 91

The purpose of the study was to establish a useful animal model for quantification of itching and to examine whether the wavelengths inducing itching were identical to those inducing erythema. Four groups of hairless mice were irradiated with 4 different light sources in order to provoke itch. The light sources were adjusted to give equal erythrogenic doses. The groups were treated 5 times weekly for a year. For the first 16 weeks the daily dose was 0.6 minimal erythema dose (MED) and for the following 36 weeks 1.2 MED. The severity of the itching in the 4 groups and in a control group of untreated mice was compared. The chosen parameters were the number of scratch-sequences and the summarized time of scratching during an observation period of 1 h. Ultraviolet irradiation provoked itching. Especially the wavelengths 315-330 nm were more itch-provoking than erythemogenic. The difference between the control group and a group treated with Philips TL12 combined with a Tempax filter was significant. An action spectrum of itching does not seem to be identical to the erythema action spectrum. The animal model described is usable to quantify itch but has to be simplified. Of the lamps used, Philips TL01 was the least itch-provoking lamp type and may be preferred in the treatment of itching diseases.
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PMID:Scratching and ultraviolet irradiation: an experimental animal model. 818 99

The feasibility of iontophoretic transdermal delivery of tranilast (N-(3,4-dimethoxycinnamoyl) anthranilic acid) for the treatment of keloid and hypertrophic scars was evaluated in hairless rats and humans. A drug electrode containing tranilast 1.5 ml (8 mg/ml in ethanol/water (8/2, v/v) mixture) was placed on the dorsal skin surface of anaesthetised rats or the affected parts of patients, and connected to the negative pole; an electric current (0.5-4 mA for rats, 2 mA for people) was pulsed through at one minute intervals. Tranilast was effectively delivered transdermally iontophoretically into the restricted skin tissues of hairless rats and the affected parts of four patients with hypertrophic scars with no skin damage. In four other patients tranilast given iontophoretically for a period of 30 minutes a week reduced the patients' complaints of pain and itching after only one or two treatments although there were some variations among patients. These results indicate that the transdermal iontophoretic delivery of tranilast is a useful treatment for keloid and hypertrophic scars, particularly for relieving pain and itching, and is more beneficial than tranilast given orally.
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PMID:Treatment of keloid and hypertrophic scars by iontophoretic transdermal delivery of tranilast. 923

In a study on the dose-response relationship for longwave UVA (UVA1; 340-400 nm) carcinogenesis in hairless mice scratch marks appeared after months of daily exposure as an unwanted side effect. Tumor induction in the highest of the 4 tested dose groups (receiving a daily dose of 430 kJ/m2 of 365-nm radiation) could not be determined because extensive scarification occurred prior to the development of any tumors. The induction of scratch marks could be scored and quantified in all 4 dose groups tested. The UVA1 dose-dependencies for the induction of tumors and scratch marks were compared. We found that the induction of scratch marks depended mainly on the cumulative UVA1 exposure, whereas tumor induction showed a lesser dose-dependency. An attempt was made to prevent the apparent pruritogenic effect of UVA1 irradiation and to understand its mechanism. The influence of ketanserin, a serotonin/histamine antagonist, on the UVA1 induction of scratch marks was tested in groups of 8 mice daily irradiated with 430 kJ/m2. No difference was found between treated and untreated animals. Histological examination of skin biopsies from irradiated mice from the 430-kJ/m2 dose group from the UVA1 carcinogenic experiment, showed no changes in numbers of mast cells or other inflammatory features when compared to skin biopsies from unirradiated control mice. This indicated that UVA1-induced scratching is not mediated through mast cell release of serotonin and/or histamine. An adequate therapeutic treatment which can prevent UVA1-induced scratching would enable us to test tumor induction with UVA1 over a larger dose range, and may provide additional insight in how this radiation damages the skin. It remains conjectural whether there exists an analogous UVA-induced pruritus in human skin.
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PMID:Chronic UVA (365-nm) irradiation induced scratching in hairless mice: dose-time dependency and the effect of ketanserin. 941 16

The ascomycin macrolactam derivative pimecrolimus (Elidel, SDZ ASM 981; Novartis Pharma AG, Basel Switzerland) is a cell-selective inhibitor of inflammatory cytokines specifically developed for the treatment of inflammatory skin diseases, such as atopic dermatitis, allergic contact dermatitis, irritant contact dermatitis, and plaque-type psoriasis. It inhibits the production of inflammatory cytokines in T cells and mast cells and prevents the release of preformed inflammatory mediators from mast cells. Topically administered pimecrolimus is as effective as the high-potency corticosteroid clobetasol-17-propionate in a pig model of allergic contact dermatitis (ACD). Unlike clobetasol, however, it does not cause skin atrophy. Given orally, pimecrolimus is as potent or superior to tacrolimus (FK 506) in treating ACD in mice and rats. Pimecrolimus also effectively reduces skin inflammation and pruritus in hypomagnesemic hairless rats, a model that mimics acute signs of atopic dermatitis. Pimecrolimus shows only a low potential to impair systemic immune responses when compared with tacrolimus as shown in rats in (1) the localized graft-versus-host reaction, (2) the antibody formation to sheep red blood cells, and (3) kidney transplantation. Pimecrolimus permeates through pig skin in vitro at a 10-times lower rate than tacrolimus, indicating a lower potential for percutaneous absorption in vivo. The data suggest that pimecrolimus combines high anti-inflammatory activity in the skin with a low potential to impair systemic immune reactions.
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PMID:Pimecrolimus (Elidel, SDZ ASM 981)--preclinical pharmacologic profile and skin selectivity. 1177 Sep 10

Experimental scratching in animals has hitherto been provoked by substances injected into the skin or central nervous system. We aimed to investigate if spontaneous scratching in the rat can be reduced by sedatives and antipruritics, and to assess if spontaneous scratching is elicited from the skin or the central nervous system. It may also be a complex behaviour related to the rat species, different from clinical itch. Eight male hairless rats were studied for 6 weeks. The animals were recorded on videotape in the middle of the day and at night, and the scratching activity was counted. The following substances were tested sequentially: midazolam, mepyramine, a eutectic mixture of lignocaine and prilocaine (EMLA, betamethasone dipropionate and a vehicle. On days 1-3 of each sequence, the test material was applied to a 42-cm(2) area on the rostral part of the back. Subsequent treatment of the whole body was made on day 4. Midazolam was injected intraperitoneally from day 1 to day 4. After 4 days of treatment, there was a wash-out phase of 3 days until the next sequence. We found a positive correlation between minutes awake and number of scratch episodes. Spontaneous scratching was lower after mepyramine on day 4 (p = 0.046) and after midazolam injections on days 1-3 (p = 0.009) and day 4 (p = 0.003). The local anaesthetic, EMLA, did not significantly influence spontaneous scratching. In conclusion, only the drugs with sedative properties suppressed spontaneous scratching, which is probably a cerebral phenomenon or otherwise explained general behaviour, rather than a reaction to skin stimuli. Thus, for testing of topically applied antipruritics, spontaneous scratching cannot be used as an animal model. Furthermore, evaluation of provocative scratching should eliminate/exclude spontaneous scratching.
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PMID:Suppression of spontaneous scratching in hairless rats by sedatives but not by antipruritics. 1221 83


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