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Biomedical subjects

W Schalla

Publications and source records attributed to W Schalla.

At least 19 recordsLinked to original sources
PubMed1998

Assessment of the impact of a CD4+ T-cell testing laboratory improvement program.

OBJECTIVE: To evaluate the effectiveness of the Centers for Disease Control and Prevention's CD4+ T-cell laboratory testing improvement program and the influence of other laboratory improvement programs on CD4+ T-cell testing practices. DESIGN: Surveys asking for practice changes and factors that influenced the changes, a survey of clinicians' perceptions of laboratory quality in CD4 testing, and analysis of data from the Model Performance Evaluation Program. INTERVENTIONS: Centers for Disease Control and Prevention interventions included a series of 3-day workshops on flow cytometry, CD4+ T-cell testing guidelines published in the Morbidity and Mortality Weekly Report, the Clinical Laboratory Improvement Amendments of 1988, and the Model Performance Evaluation Program. PARTICIPANTS: All known laboratories in the United States that perform clinical CD4+ T-cell testing, workshop participants, and a sample of clinicians that treat patients infected with the human immunodeficiency virus. MAIN OUTCOME MEASURES: Changes in practices, factors most influential in effecting change, and performance on samples mailed to laboratories by the Model Performance Evaluation Program; knowledge before and after presentation of material in workshops; and practicing clinicians' observations of any effects of changes in laboratory practices. RESULTS: Many existing laboratories changed practices as a result of both governmental and nongovernmental CD4+ T-cell testing improvement programs. Sources of influence varied with each testing practice. Perceptions that test results were more reproducible seemed to offset presumed increases in the time and cost of testing. Clinicians who had ordered CD4+ T-cell testing for more than 10 years noted some improvements in results reported. CONCLUSIONS: As new complex testing methodologies are introduced into clinical and public health laboratories, the users seem to seek guidance in appropriate application of preanalytic, analytic, and postanalytic phases of the testing process. Testing improvement programs from a variety of sources were credited with changing practices and should continue to provide this guidance.

CD4 Lymphocyte Count↗
PubMed1991

Potency assessment of topical corticoids in the vasoconstrictor assay and on tuberculin-induced inflammation.

The topical anti-inflammatory activity of potent and very potent corticoids was studied in normal and inflamed skin using the vasoconstriction assay and tuberculin-induced inflammation in four double-blind intraindividual comparison trials. Instrumental techniques in addition to visual scores and several time points were applied to get better insight into the reliability of the models and the sensitivity of the different variables. Beta-methasone-17-valerate and two concentrations of prednicarbate were used as potent corticoids, clobetasol-17-propionate, betamethasone-17,21-dipropionate and different biopharmaceutical forms of desoximetasone (DOM) as very potent corticoids. Visual scores, the reactive skin hyperemia after arterial occlusion and skin colorimetry were used to quantify vasoconstriction; erythema scores, surface area of infiltration and changes in skin colorimetry, skin blood flow and skin temperature for the tuberculin reaction. The time courses of blanching (n = 20) and of the tuberculin reaction (n = 10) were described by orthogonal polynomials and the coefficients were statistically analyzed by nonparametric tests, the discriminative variables in tuberculin inflammation in addition by the parametric multiple analysis of variance. Important differences in the release rates of corticoids demand several assessment times and not just one as often used. The potency ranking may otherwise be misleading. In general, ointments released corticoids slowlier than the cream which in turn liberated slowlier than the gels. The DOM gel declined rapidly after an apparent peak at 5.5 h in terms of its blanching effect, but was nevertheless comparable after once-daily application to other very potent corticoids in its activity against delayed-type inflammation. Such differences may explain discrepancies found for some corticoid preparations between their blanching response and clinical efficacy. The more potent a corticoid the more the erythema is reduced, the less pronounced the cell infiltration and the more delayed the peak seems from 24 to 48 h in the tuberculin reaction. The inflammatory response is diminished in the following manner: very potent greater than potent corticoids; erythema greater than infiltration. Visual scores were the most reliable parameters in normal and inflamed skin and they correlated well with skin colorimetry which shows greater variability. Reactive hyperemia after arterial occlusion gave poor results in terms of ranking in the vasoconstriction assay as did resting skin blood flow in inflamed skin. Changes in the temperature of inflamed skin are sensitive enough to discriminate the active drugs from the controls, but have a somewhat different time course, reflecting perhaps a higher impact of the amount of mediator release in the early phase relative to the cell invasion in the later phase.

Administration, Topical↗
PubMed1987

Influence of an essential fatty acid deficient diet on absorption of topical hydrocortisone in the rat.

Using a rat dermatosis model, produced by dietary essential fatty acid deficiency (EFAD), which is characterized by histological changes and elevated transepidermal water loss, changes in skin permeability were studied using [14C]-hydrocortisone (HC). Skin, serum and urinary levels of HC were measured, and absorption and excretion of HC in EFAD rats compared with that in control rats on a normal diet. This animal model has demonstrated the importance of the functional integrity of the horny layer in skin penetration.

Administration, Topical↗
PubMed1984

Short contact anthralin therapy of psoriasis with and without UV-irradiation and maintenance schedule to prevent relapses.

A short term anthralin application schedule was used at home in 42 patients with severe psoriasis. In another group of 21 patients treated at our day care center, UV-B irradiation was added when the surplus of anthralin had been washed off. Good healing results within 3-8 weeks were noted in most patients. To prevent relapses 31 patients continued the anthralin treatment once or twice a week after healing. In 15 cases this was combined with UV irradiation. One patient relapsed after a severe infection, but 16 others were observed for 6-9 months and 14 for 3-5 months without relapses. Irritation of non-affected skin is common especially at the beginning of the treatment and some staining of clothes and linen can occur. With proper information about this, the treatment is well accepted by the patient who generally finds it reasonably simple without the need of special protective dressings.

Adult↗
PubMed1981

[The risks of photochemotherapy (author's transl)].

The side effect of phototherapy with 8-methoxypsoralen was divided in short- and longterm damage. From 1969 till 1980 2 013 patients were treated. The pattern of alteration by PUVA depends on doses, continuance of therapy and type of dermatoses as psoriasis, vitiligo, mycosis fungoides, physical urticarias, chronic eczemas. The spontaneous development of tumors, the initiating or promotion of tumors by PUVA as well as a regression of tumors by PUVA has to be taken into account regarding the absolute numbers of tumors after PUVA-therapy. The risk of the PUVA-therapy depends on the doses of continuance of the treatment including the combination with other sources of radiations or natural sun-exposition. The possibilities of drug combinations to lower the total doses of light energy are discussed according the recommendation of several teams in Germany.

Chronic Disease↗
PubMed1980

Minimum phototoxicity dose (MPD). Comparison of conventional light sources and different lasers.

A pilot study was performed on groups of 5-7 volunteers to evaluate the minimum phototoxicity dose (MPD) of several light sources with different UVA qualities to optimise photochemotherapy. Visual observation was more suitable than reflection photometry in determining the threshold and gradation of erythema reactions; thermometry gave poor results. There were no individual differences between the MPD of a PUVA 4000 box and a continuously emitting argon-ion laser with 40 and 400 mW, respectively. The pulsed radiation of a nitrogen laser was the most effective. The limited validity of the Bunsen-Roscoe law for high peak power could thus be tested for a secondary photochemical reaction of the skin. The nitrogen laser (337.1 nm) proved that a repetition rate of 20 Hz was superior to 10 and 40 Hz. The MPD was intraindividually higher at 25 Hz than at 10 and 16.7 Hz for the dye laser tested (325 and 330 nm, respectively).

Dose-Response Relationship, Radiation↗
PubMed1979

Melanin granula distribution and phagocytosis in psoriasis vulgaris after PUVA therapy.

Melanin-containing basal cells of the epidermis, melanin-containing macrophages, mast cells, eosinophilic granulocytes and plasma cells were quantitatively investigated with the purpose of gaining an understanding of the quantitative changes in these cell systems under PUVA therapy. This patients have been exposed to solar radiation some weeks or months before the begin of the PUVA-treatment. Different dying-processes were used to investigate biopsy samples of psoriatically healthy and psoriatically affected skin, from 28 patients before, and 39 patients after PUVA therapy, using a 2 d micrometer with a field of view of 0.1 mm2. Altogether more than 9,000 fields of view have been analysed. The average radiation amount was 12 irradiations with an average total energy of 21.5 J/cm2. It was found that the count of granula-containing basal layer cells decreases in the psoriatic "healthy" region due to pigment incontinence and increase in the psoriatically affected region. The subepidermal melanin-containing phagocytes increase in both regions to a similar extent. In the case of the mast cells there was no trend to degranulation. The count of eosinophilic granulocytes and plasma cells was unchanged.

Eosinophils↗
PubMed1979

Contraception via topical application? - A review.

The skin, generally speaking, is not an absorption organ but one of its major functions is the protection of the body against the entrance of foreign material. Under certain circumstances, however, drugs can be introduced into the skin and thereby into the body as can be seen in the topical treatment of skin diseases. Though percutaneous pharmacokinetics of steroids seem appropriate for contraception, the variability of the absorption process appears to be too high for this purpose.

Absorption↗