Demonstration of cellular retinoic acid binding protein in cultured human skin fibroblasts

Previous studies have indicated that retinoids, such as all-trans-retinoic acid and 13-cis-retinoic acid, can modulate connective tissue metabolism in human skin fibroblast cultures. Such effects could be mediated through binding of these retinoids to specific cellular binding proteins. In the present study we have demonstrated cellular retinoic acid binding protein using both whole cell and cytosol binding assays with [3H]all-trans-retinoic acid or [3H]13-cis-retinoic acid as the ligand. Specific binding of [3H]all-trans-retinoic acid could be demonstrated by both techniques and the binding could be displaced by unlabelled all-trans-retinoic acid and 13-cis-retinoic acid, but not by retinol or RO-10-9359 (etretinate) in a 100-fold excess. Gel filtration chromatography of the cytosol proteins after incubation with [3H]all-trans-retinoic acid demonstrated that the specific binding protein had an apparent molecular weight of approximately 15 000 daltons. Thus, the cellular retinoic acid binding protein demonstrated in human skin fibroblasts may mediate the effects of the retinoids on connective tissue metabolism in these cells.     

QUANTITATIVE HISTOCHEMICAL ANALYSIS OF MAST CELLS AND SENSORY NERVES IN PSORIATIC SKIN

To study the elements of neurogenic inflammation in psoriatic skin, morphological contacts were examined between mast cells and sensory nerves containing the neuropeptides substance P (SP), calcitonin gene-related peptide (CGRP) or vasoactive intestinal polypeptide (VIP). Because mast cells in psoriatic lesions appear in great numbers at the basement membrane (BM) zone, neuropeptide–mast cell contacts with the BM were also counted. A double stain for active mast cell tryptase and the neuropeptides was applied and the contacts were quantitated morphometrically. Sensory nerve–mast cell contacts were also studied three-dimensionally with a confocal laser scanning microscope. Increases in the contact values of SP and CGRP with mast cells, as well as with the BM, were obtained in developing (1–3 weeks) lesions when compared with their non-lesional controls. This increase reached statistical significance in mature lesions. In contrast, the corresponding contact values for VIP were decreased. By confocal microscopy, a close association between mast cells and sensory nerves was observed in the lesional dermis. Since tryptase is known to degrade CGRP but not SP, neurogenic stimuli, mainly via SP, can result in degranulation of mast cells, which release substances to enhance inflammation. At the BM zone in psoriatic lesions, the numerous mast cells loaded with tryptase can promote degradation of BM components and allow entry of various mediators to interact with keratinocytes.     

A THREE-STEP PROCEDURE FOR ASSESSING BIOEQUIVALENCE IN THE GENERAL MIXED MODEL FRAMEWORK

Bioavailability data arising from a standard two-period cross-over study are routinely analysed to establish bioequivalence between test and reference formulations. Current regulatory guidelines only require evidence of equivalence in average bioavailability for the assessment of bioequivalence. Under normality assumptions, this is achieved by demonstrating equivalence between the formulation means (step 1). However, the equivalence of formulation variances should also be assessed to get evidence of population bioequivalence (step 2), since a difference in variability of bioavailability may also pose significant problems in drug safety and efficacy. On the other hand, even population bioequivalence does not ensure that an individual subject could be expected to respond similarly to the two formulations. Therefore, whenever individual bioequivalence is the ultimate goal, the magnitude of intra-subject correlation should always be examined as the final stage (step 3). In this paper, these three successive concepts of bioequivalence are cast into the general mixed model framework and a stepwise testing procedure for the global assessment of bioequivalence is proposed. In addition to this, important issues addressed in the regulatory guidelines, such as verification of the model assumptions and application of the log-transformation, are discussed. Lastly, an example is presented to illustrate the proposed three-step procedure on the original and log-transformed scale of measurement.     

ESTIMATION BY DATA AUGMENTATION IN REGRESSION MODELS WITH CONTINUOUS AND DISCRETE COVARIATES MEASURED WITH ERROR

Estimation methods are considered for regression models which have both misclassified discrete covariates and continuous covariates measured with error. Adjusted parameter estimates are obtained using the method of data augmentation, where the true values of the covariates measured with error are regarded as missing data. Validation data on the covariates are assumed to be available. The distinction between internal and external validation data is emphasized, and its effects on the analysis are examined. The method is illustrated with simulated data. © 1997 by John Wiley & Sons, Ltd.     

Dietary calcium intake and its relation to bone mineral density in patients with inflammatory bowel disease

Objectives. To investigate calcium intake and its association with bone mineral density (BMD) and the type and extent of the disease in patients with inflammatory bowel disease (IBD).
Setting. University hospital clinic.
Subjects. A total of 152 unselected IBD patients and 73 healthy controls.
Measurements. Dietary calcium intake was assessed with a food frequency questionnaire and BMD of the lumbar spina and proximal femur was measured.
Results. The IBD patients had lower dietary calcium intake (1034 [SD 493] mg) than the controls (1334 [514] mg, P <0.001). The difference was significant in the males (1047 [552] mg and 1575 [586] mg, respectively, P <0.001), but not in the females (1020 [422] mg and 1112 [303] mg). The dietary daily calcium intake was below 1000 mg in 53% of the patients and 27% of the controls ( P = 0.0004) and below 400 mg in 9.2% of the patients and none of the controls ( P =0.007). The calcium intake was not associated with the severity or the type of IBD. Seventy-one (47%) patients and eight (11%) controls avoided lactose in their diet ( P < 0.001). In the IBD patients, no association between the calcium intake and BMD was detected, whereas in the controls a positive correlation between the calcium intake and the BMD of the proximal femur was found.
Conclusions. Calcium intakes below the recommendations are seen more often in the IBD patients than in the healthy controls, but in the IBD patients the calcium intake is not associated with BMD in a cross-sectional study. A low-lactose diet is common among IBD patients. To reduce the risk of inadequate calcium intake, unnecessary dietary restrictions concerning, e.g. milk products, should be avoided for these patients.     

A population-based analysis of variation in Caesarean birth rates

Our aim was to find hospital characteristics and indicatorsof clinical practice patterns associated with hospital Caesareanbirth rates. The data were derived from the national FinnishBirth Registry for 1987 and 1988 (n=120,277). In addition tohospital-specific Caesarean birth rates, rates in geographicallydefined hospital service areas were used. This was done to controlfor selection due to referrals. Few hospital characteristicsexamined were associated with Caesarean birth rates. There wasa negative relationship between the hospital service area-specificrate, but not between the hospital specific rate and the sizeand level of the hospital. This was due to a referral systemin which small, level I hospitals manage mainly low-risk deliveries.High Caesarean birth rates were characterized by frequent operationsamong normal birth weight, full-term deliveries and for dystoda.The relative excess of Caesareans was seen only at times convenientfor surgery. Low Caesarean birth rates were characterized byless Caesareans for all major indications and at all times ofthe day and week. We conclude that insufficient adaptation ofclinical practice patterns to fit a low-risk case mix in a hospitalmay lead to unnecessary operations. High Caesarean birth ratesare not characterized by aggressive management of risks, butby a dispersion of operations among the normal population.     

Verrucous lesions in patients with discoid lupus erythematosus

Seven cases of classical discoid lupus erythematosus of the face associated with hyperkeratotic, papulo-nodular lesions on the arms and hands were studied. Clinically the hyperkeratotic lesions resembled keratoacanthomas or hypertrophic lichen planus. The clinical course was marked by chronicity, an absence regression of the lesions, and resistance to treatment. Histopathologically, a lichenoid cellular reaction seemed to play a key role in the development of the hypertrophic lesions which resembled either keratoacanthomoas or hypertrophic lichen planus. Elastic fibres were prominent in the upper dermis, the lower levels of the epidermis and in the hyperkeratotic horny layer. Immunofluorescence of the papulo-nodular lesions demonstrated the deposition of IgG and IgM in a globular pattern at the dermal-epidermal junction. Discontinuous deposition of these antibodies was also seen at the basement membrane zone. On the basis of the immunofluorescence, histopathological and clinical studies, we suggest that the verrucous, hyperkeratotic lesions on the upper extremities represent an unusual, but distinct, form of discoid lupus erythematosus.