A Tridimensional View of Intradermal Nevi as Revealed by Scanning Electron Microscopy

When scanning electron microscopy (SEM) was applied to the study of intradermal nevi, interesting tridimensional features were recognized. The free surface of the lesions showed ruffled keratinized cells. "Normal" hairs as well as "corkscrew" hairs emerged from the follicular openings. Nevus cells were either round or elongated and surrounded by connective tissue fibers.     

Centroblastic transformation of chronic lymphocytic leukaemia with primary skin involvement—cutaneous presentation of Richter's syndrome

The development of a large-cell non-Hodgkin's lymphoma in a patient suffering from chronic lymphocytic leukaemia is known as Richter's syndrome, representing one of the possible anaplastic transformations of the leukaemia. Cutaneous involvement is an extremely rare event. The case of a 45-year-old man with B-cell chronic lymphocytic leukaemia is reported. Five years later multiple cutaneous nodules developed on his extremities. Biopsies of the skin showed a diffuse large-cell lymphoma, bearing the same cell surface immunoglobulin light chain isotype as the leukaemia, suggesting the original relationship between both neoplasms.     

CD69 is a stimulatory receptor for natural killer cell and its cytotoxic effect is blocked by CD94 inhibitory receptor

CD69 is a differentiation antigen expressed shortly after activation on T lymphocytes and other cells of haematopoietic origin, including natural killer (NK) cells. The function of CD69 on T lymphocytes acting as a costimulatory molecule in proliferation and lymphokine secretion is well established. NK cells express CD69 after activation by different stimuli such as phorbol 12-myristate 13-acetate (PMA), interleukin (IL)-2, IL-12, interferon-alpha (IFN-alpha) or anti-CD16 monoclonal antibodies (mAbs). However, although it has been shown that CD69 triggers NK-cell-mediated cytolytic activity, its effect on other NK-cell functions has not been studied. Furthermore, the possible interaction of CD69 triggering with other C-lectin type inhibitory receptors is not known. Thus, the objective of this work is to determine whether CD69-mediated NK cytotoxicity can be regulated by CD94 inhibitory receptor and the role of CD69 on other NK-cell functions different of cytotoxicity. The results show that CD69-mediated NK cytotoxicity can be abrogated by CD94 stimulation in NK cells expressing the CD94 inhibitory form of the receptor, indicating that CD94 regulates the cytotoxic events initiated by a wide variety of NK activatory receptors. We also show that anti-CD69 mAbs, not only triggered NK cytotoxicity, but also induce NK-cell proliferation, CD25 and intracellular adhesion molecule-1 (ICAM-1) expression, TNF-alpha production and Ca2+ mobilization in preactivated NK cells. These results suggest that CD69 plays a crucial role in NK-cell function contributing to sustain NK-cell activation, as it has been previously demonstrated in T cells.     

Naevus spilus as a precursor of cutaneous melanoma: report of a case and literature review

Naevus spilus is defined as a melanocytic macule in which there are dark maculopapular speckles. We describe a patient with a superficial spreading malignant melanoma arising in a congenital naevus spilus, and review the literature on this association.     

Conformation and dynamics of the chemotactic peptide formyl-L-methionyl-L-leucyl-L-phenylalanine in solution

Several conformational and dynamic features of the chemotactic peptide formyl-L-methionyl-L-leucyl-L-phenylalanine in solution have been delineated by investigations of NMR and IR spectroscopic parameters. Both 1D and 2D NMR experiments have been performed for detection of scalar and dipolar proton-proton connectivities, whereas ¹³C and ¹H relaxation parameters have been interpreted in terms of molecular dynamics. The main conformation appeared to be unfolded with the three hydrophobic side chains extending in divergent directions with respect to the backbone. The existence of relatively weak inter-molecular hydrogen bonds was demonstrated, involving the formamide end group, with increase in the hydrophobicity of the external surface.     

Effects of Oral Propafenone Therapy on Chronic Myocardial Pacing Threshold

The effects of oral propafenone therapy on pacing threshold were studied in 36 patients chronically paced for sick sinus syndrome or AV block. The pacemakers, all unipolar models and with noninvasive threshold measurement facilities, were: 9 VVI, 15 AAI, and 12 DDD. Each patient received an initial propafenone dose of 450 mg/day, that in 18 cases was increased to 900 mg/day. Threshold was tested at baseline and at each dosage after 7 days of therapy. With the lower propafenone dosage the threshold, measured at 2.5 V, rose from 0.14 +/- 0.10 to 0.21 +/- 0.16 msec (+55%) in the atrium (P less than 0.0001) and from 0.10 +/- 0.08 to 0.15 +/- 0.09 msec (+63%) in the ventricle (P less than 0.0001). In the 18 patients who received both dosages, the mean atrial and ventricular threshold increased from 0.12 +/- 0.10 to 0.17 +/- 0.14 msec with the lower dose and to 0.27 +/- 0.22 msec (+125%) with the higher dose (P less than 0.0001 for both increments). With the 900 mg/day dose, a threshold increment greater than or equal to 300% was observed in 15% of the stimulated chambers. A good linear correlation (r = 0.76) was found between the ventricular threshold increment and the drug induced QRS widening. In conclusion, treatment with oral propafenone increases atrial and ventricular stimulation threshold in pacemaker patients. Threshold increment is dose dependent and proportional to the drug induced QRS widening. In the majority of the cases the threshold increment is not clinically significant, but caution must be used in prescribing high doses of the drug to patients with high baseline threshold.     

Prognostic implications of DNA aneuploidy in 156 untreated multiple myeloma patients

In this study the incidence of DNA aneuploidy in a large series of untreated multiple myeloma (MM) patients was assessed in order to determine its clinical and prognostic significance. A total of 156 MM patients were included in the study. DNA measurements were performed in all cases at diagnosis using two different flow cytometry methods: (1) propidium iodide (PI) staining on isolated nuclei, and (2) CD38/PI double staining on whole cells. The DNA ploidy status was correlated with the most relevant clinical and haematological disease characteristics. From the 156 cases analysed, 91 (58%) were aneuploid (56% hyperdiploid and 2% hypodiploid). The correlation between the two techniques on the detection of DNA aneuploidy was excellent, although CD38/PI double staining would be preferable in cases with <5% of DNA aneuploid plasma cells (PC). Upon comparing the clinical and haematological disease characteristics of hyperdiploid versus diploid cases, the former group was characterized by a lower age, reduced incidence of anaemia, lower 02M levels, higher proliferative activity within the residual normal haemopoietic cells, increased expression of CD 5 6 antigen in PC, and higher proportion of PB CD4⁺ T cells. In contrast, diploid cases had a higher expression of the CD10, CD20 and CD15 antigens and greater numbers of PB CD56⁺CD3 NK cells (P < 0–05). Circulating PC were identified in six cases, all being diploid. Overall survival was significantly longer in hyperdiploid compared to diploid MM (P = 0–02).     

Ultrastructural Basis for the Assay of Topical Acne Treatments. Transmission and Scanning Electron Microscopy of Untreated Comedones

After two decades of using systemic antibiotics as a main treatment for acne, emphasis is again being placed on topical agents. Thus, it is highly desirable to have a procedure whereby the activity of the various compounds can be evaluated by direct visualization. Scanning electron microscopy combined with transmission electron microscopy provide the tools for such in assay. This study describes the ultrastructure of untreated comedones and provides the baseline or control data necessary for testing topical treatments. Comedones obtained by punch biopsies or comedo extractors were processed for electron microscopy and studied with an ETEC Autoscan Scanning Electron Microscope and with Philips EM 300 and EM 301 Transmission Electron Microscopes. Microorganisms, keratinized cells, sebum, and hairs interact with each other to form the comedonal mass. Corynebacterium acnes and Pityrosporum ovale proliferate abundantly in close association with sebum and penetrate the keratinized cells. Fine structural details of bacteria and yeasts as well as features of host-microbial relationship have been elucidated.