Pityriasis alba: a study of pathogenic factors

BACKGROUND: The aetiology of pityriasis alba (PA), a common dermatosis in childhood, is still controversial. The objective of this study was to assess the possible aetiopathogenic factors of this disease in infants. METHODS: Forty-four patients with PA and 31 healthy children were examined and compared. Personal hygiene habits, sun exposure, presence of Staphylococcus aureus in nasal fossae and presence of major or minor signs of atopy were assessed during anamnesis and physical examination. Susceptibility to ultraviolet (UV) B radiation was measured by the onset of a contact hypersensitivity reaction to diphenylcyclopropenone in individuals sensitized in previously irradiated areas. RESULTS: The prevalence of PA was higher in individuals with darker skin, in high phototype categories, as well as in males. The number of daily baths and sun exposure between 10.00 h and 15.00 h were significantly higher in the PA group when compared with controls (P = 0.03 and P = 0.0015, respectively). The presence of atopy signs was more common in pityriasis patients (P = 0.002). Susceptibility to UVB radiation was 29.6% in the PA group vs. 29.0% in the control group; nevertheless, important differences were found after stratification in order to control possible confounding factors. The presence of S. aureus in the nostrils was equal in both groups. CONCLUSIONS: Our results confirm that PA, in our population, is more prevalent in males and in individuals in higher phototype categories. In those with inadequate personal hygiene and sun exposure habits the disease is more accentuated, demonstrating that the xerosis presenting in individuals with atopic diathesis is an important element in the development of the disease. S. aureus is not an important aetiopathogenic factor in PA. Susceptibility to UVB becomes important when related to the patient's phototype.     

Synergistic cytotoxic effect of azidothymidine and recombinant interferon alpha on normal human bone marrow progenitor cells

Azidothymidine (AZT) and interferon alpha (IFN-alpha) are among the drugs showing strong in vitro activity against the human immunodeficiency virus type-1 (HIV-1). Each drug, however, has significant toxicity against normal marrow progenitor cells that frequently proves dose-limiting in patients. In this study, AZT and recombinant IFN-alpha 2a (rIFN-alpha 2a) were tested as single agents and in combination against normal myeloid (CFU-GM) and erythroid (BFU- E) colony forming cells in a standard methylcellulose culture assay. The data were analyzed using a quantitative computerized analysis based on the median-effect principle and the isobologram equation as described by Chou and Talalay (Adv Enz Regul 22:27, 1984). The ED90 for BFU-E and CFU-GM inhibition was then compared with previously measured in vivo plasma levels of each drug and the ED90 for the anti-HIV-1 effect in vitro. We demonstrate that (a) the drugs are strongly synergistic in inhibiting marrow progenitor cell growth and that this synergism occurs at drug levels that are within the range of measured plasma levels in phase I clinical trials, (b) BFU-E are more sensitive than CFU-GM to the inhibiting effects of AZT, rIFN-alpha 2a or both drugs in combination, (c) the drug concentrations in combination that synergistically inhibit bone marrow progenitors are much higher than those required to inhibit HIV-1 replication in vitro, and (d) the anti- HIV-1 effect for the combination of AZT and rIFN-alpha 2a was clearly superior to the effect of AZT or rIFN-alpha 2a alone as indicated by the combination index and the dose-reduction index. These data suggest that substantially lower doses of AZT and rIFN-alpha than those currently being tested in clinical trials might not only maintain a strong synergistic anti-HIV-1 effect but might also avoid significant hematologic toxicity.     

Intraluminal calcifications in the small bowel of newborn infants with total colonic aganglionosis

Intraluminal calcifications were found in the small bowel of 4 newborns with total colonic aganglionosis. Abdominal radiography demonstrated circular aggregations of small punctate calcific densities in the right lower quadrant and evidence of bowel obstruction. There was a microcolon in each case. The calcifications, which resemble those seen in small intestinal atresia and stenosis, are probably related to fetal intestinal stasis, and may be differentiated from those due to meconium peritonitis.     

Magnetic resonance imaging of the brainstem: normal structure and basic functional anatomy

Normal structure and basic functional anatomy of the brainstem were studied using anatomic sections obtained with a cryomicrotome whole-organ sectioning technique. Major tracts and nuclei were identified and their function summarized. Magnetic resonance imaging of the brainstem was performed on 10 normal volunteers. By comparing these images with the corresponding anatomic sections, normal structures, including major tracts and nuclei, were identified. Knowledge of location and function of clinically important brainstem nuclei and tracts is necessary for optimal magnetic resonance image interpretation.     

A comparative study on the morphology and topography of the ciliary ganglion in midday gerbil (Meriones meridianus) and turtle (Agrionemys horsfieldii).

The morphology and topography of the ciliary ganglia in the midday gerbil and turtle were studied with use of histochemical and histological techniques. The ciliary ganglion of the midday gerbil consisted of two cell agglomerations: the main ganglion and the accessory ganglion. The main ganglion was situated in the orbit and usually closely attached to the nerve for the inferior oblique muscle. The short ciliary nerves arose from the superior end of the main ganglion and reached the orbit. The accessory ciliary ganglion was smaller than the main ganglion. Usually it was attached to short ciliary nerves. The ganglionic neurocytes, 25.97 microm in diameter, were distributed regularly over the entire surface of the main ganglion. They typically had a single clear nucleus. The ciliary ganglion in the turtle formed a characteristic triangular structure on the inferior branch of the oculomotor nerve. The histological examination showed a small number of nerve cells in comparison to the nerve fibres. The neurocytes were placed mainly in the nasal part of ganglion and they had an irregular arrangement. The average diameter of neurons was 23.55 microm. Significant differences in density of ganglionic components in both species were observed. In midday gerbil the cells were densely packed and took up about 80% of a cross-section, while, in the turtle, neurocytes were located mainly in the surface part of ganglion.