Kaposi sarcoma following postmastectomy lymphedema

Classical Kaposi sarcoma (KS) usually appears on lower extremities accompanied or preceded by local lymphedema. However, the development in areas of chronic lymphedema of the arms following mastectomy, mimicking a Stewart–Treves syndrome, has rarely been described. We report an 81‐year‐old woman who developed multiple, erythematous to purple tumors, located on areas of post mastectomy lymphedema. Histopathological examination evidenced several dermal nodules formed by spindle‐shaped cells that delimitated slit‐like vascular spaces with some red cell extravasation. Immunohistochemically, the human herpesvirus type 8 (HHV‐8) latent nuclear antigen‐1 was detected in the nuclei of most tumoral cells confirming the diagnosis of KS. Lymphedema could promote the development of certain tumors by altering immunocompetence. Although angiosarcoma (AS) is the most frequent neoplasia arising in the setting of chronic lymphedema, other tumors such as benign lymphangiomatous papules (BLAP) or KS can also develop in lymphedematous limbs. It is important to establish the difference between AS and KS because their prognosis and treatment are very different. Identification by immunohistochemistry of HHV‐8 is useful for the distinction between KS and AS or BLAP.     

Incidence of leukocytoclastic vasculitis in chronic idiopathic urticaria. Study of 100 cases

One hundred cases of chronic idiopathic urticaria (CIU) were studied to determine the incidence of leukocytoclastic vasculitis (LV) and the clinical and laboratory data that might indicate its presence. LV was found in 12 patients, none of whom had either clinical or laboratory data to suggest its presence. These results suggest that a small percentage of patients with CIU. 12% in this series, have LV without either clinical or laboratory signs of its existence.     

Formation of 8-oxoguanine in cellular DNA of Escherichia coli strains defective in different antioxidant defences

This paper examines the relationship in Escherichia coli betweenthe in vivo content of 8-oxoguanine (8-oxoG) in chromosomalDNA and deficiencies of various key antioxidant defences. Thestructural genes for catalases (katG and katE), cytosolic superoxidedismutases (sodA and sodB) or formamidopyrimidine-DNA glycosylase(fpg) were inactivated to obtain bacterial strains lacking thescavenger enzymes for H₂O₂ or O₂·^– or the DNA repairprotein for 8-oxoG. Wild-type bacteria showed 5-fold increasedsensitivity to both lethality and mutagenesis by H₂O₂ in K medium(1 % casamino acids and 1 % glucose), as compared with nutrientbroth. This higher sensitivity was associated with increasedchromosomal oxidative damage, estimated as the 8-oxodG content,and with a marked decrease in both catalase and SOD activities.Bacteria lacking both cytosolic SODs (sodA sodB mutant) displayedincreased 8-oxodG content in chromosomal DNA (2.8-fold thatof the wild-type) when grown under standard aerated conditions.Comparatively, no significant difference in 8-oxodG contentwas observed in cells grown without aeration. Bacteria totallydevoid of catalase activity (katG katE mutant) showed wild-typecontents of 8-oxodG in chromosomal DNA when grown under aeratedconditions. Nevertheless, the protective role of catalase inpreventing formation of 8-oxodG in chromosomal DNA became evidentunder oxidative stress conditions: growth under hyperoxygenationand, particularly, following H₂O₂ exposure. Catalase deficiencyresulted in a dramatic decrease in viability after H₂O₂ exposure.A deficiency of Fpg protein also sensitized E.coli to H₂O₂ lethality,though to lesser extent than a deficiency of catalase activity.However, the scavenger enzyme and the DNA repair protein protectedequally against 8-oxoG formed in vivo upon H₂O₂ treatment. ¹To whom correspondence should be addressed. Tel: 57 218695; Fax: 57 218688; Email: bblpucuc{at}uco.es     

Thymic stroma is required for the development of human T cell lineages in vitro

Development of the T cell lineage is characterized by the homingof hematopoietic precursors to thymus, followed by their acquisitionof receptors for antigen. T cell receptors are ß or heterodimers associated with CD3 (TCR-CD3). Very early T cellprecursors in humans have been characterized as CD7+45+ cellswhich lack the T cell differentiation antigens CD1, CD2, CD3,CD4, and CD8. A phenotypically equivalent early thymocyte populationalso occurs in postnatal life, and we have previously shownthat interleukin 2 (IL2) promotes the development in vitro ofboth the ß and the T cells from these early thymocytes.Here we have analyzed the requirements of the induction of theIL2 pathway in early thymocytes, and their developmental potential.We show that: (I) thymic stromal cells, which are present inthymocyte suspensions, are necessary to induce the IL2 pathwayand the development of ß or T cell lineages fromearly thymocytes in vitro; and (II) when removed from the invivo environment, early thymocytes can develop in vitro intoTCR-CD3^– cells of the natural killer (NK) lineage. Weconclude that CD7+45+, CD1–2–3–4–8–early thymocytes are multipotential progenitors that, at least,have the capacity to develop into ß or T cell andNK lineages. The analysis of the mechanisms of generation andselection of human T and NK cell diversity, not feasible inbone marrow cultures, is now possible.     

Vancomycin serum concentrations in pediatric oncologic/hematologic intensive care patients

BackgroundUsual treatment regimens with vancomycin often fail to provide adequate serum levels in patients with severe infections.MethodsRetrospective analysis of vancomycin trough serum measurements. The following parameters were calculated by Bayesian analysis: vancomycin clearance, distribution volume, and peak estimated concentrations. The area under the concentration curve (AUC) (total daily dose/24 h clearance of vancomycin) was used to determine the effectiveness of treatment through the ratio of AUC/minimum inhibitory concentration (MIC) above 400, using MIC = 1 μg/mL, based on isolates of Staphylococci in cultures.ResultsSixty-one vancomycin trough measurements were analyzed in 31 patients. AUC/MIC > 400 was obtained in 34 out of 61 dosages (55.7%), but the mean vancomycin dose required to achieve these levels was 81 mg/kg/day. In cases where the usual doses were administered (40–60 mg/kg/day), AUC/MIC > 400 was obtained in nine out of 18 dosages (50%), in 13 patients. Trough serum concentrations above 15 mg/L presented a positive predictive value of 100% and a negative predictive value of 71% for AUC/MIC > 400.ConclusionHigher than usual vancomycin doses may be required to treat staphylococcal infections in children with oncologic/hematologic diseases. Since the best known predictor of efficacy is the AUC/MIC ratio, serum trough concentrations must be analyzed in conjunction with MICs of prevalent Staphylococci and pharmacokinetic tools such as Bayesian analysis.