Absence of Correlation Between Delayed-Type Hypersensitivity and Protection in Experimental Systemic Candidiasis in Immunized Mice

We found that in mice which had been immunized intraperitoneally with 2 × 10⁸ heat-killed Candida albicans cells there was a striking temporal relationship between resistance to systemic challenge with 10⁶ living C. albicans cells and a number of measurable cellular parameters of the host response. These included the emergence of delayed-type hypersensitivity and the development of granulocytosis. Since it had been shown in previous work that granulocytosis was associated with an increase in resistance when nonspecific immunostimulation was used, we performed experiments to induce delayed-type hypersensitivity without any measurable modification of the granulocyte population. Adoptive transfer of delayed-type hypersensitivity with spleen cells from immune and resistant donor mice did not produce any increase in resistance in normal recipients. When separate groups of mice were immunized intraperitoneally or subcutaneously with varying doses of heat-killed C. albicans, we found that doses of less than 10⁸ cells did induce significant delayed-type hypersensitivity without any increase in granulocytosis. In such mice, as well as in animals pretreated with immunomodulators before immunization with heat-killed C. albicans, the presence of cell-mediated immunity, as measured by the delayed-type hypersensitivity test, was not associated with an increase in resistance against systemic candidiasis. On the contrary, the results suggested that cell-mediated immunity was associated with an increase in the susceptibility of these mice. The same effect on candidiasis susceptibility was observed when animals were immunized with heat-killed filamentous C. albicans.     

Pathology of inverted Takotsubo cardiomyopathy

Myocardial dysfunction without coronary involvement may occur in acute cerebral diseases. The inverted Takotsubo pattern has been recently recognized as a novel heart neurologic stress-related syndrome. We report on the case of a 40-year-old woman presenting with massive subarachnoid hemorrhage and brain death. Echocardiography revealed an extensive left ventricular circumferential akinesis except at the apex. Histologic analysis of the heart confirmed the absence of myocardial infarction and revealed only sparse foci of myocyte necrosis with contraction bands in the akinetic areas.     

Cell extract-derived differentiation of embryonic stem cells

Various means have been used to encourage the differentiation of embryonic stem cells (ESCs) toward specific lineages, including growth factor administration, genetic modification, and coculture with relevant cells/tissues. Cell extract-based reprogramming has recently been used to derive mature cells from nonrelated phenotypes. In this communication, we tested whether this in vitro reprogramming approach can be used to direct ESC differentiation. Permeabilized murine ESCs exposed to extracts of murine type II pneumocytes showed increased expression of surfactant protein C and its corresponding mRNA, reflecting enhanced differentiation of pneumocytes. Subsequent differentiation to a type I phenotype was demonstrated by expression of aquaporin 5. Pneumocyte formation occurred quicker than with growth factor-induced differentiation. Our findings establish that ESCs can be differentiated in vitro using cellular extracts. This model provides a tool for analysis of the key factors involved in the differentiation of ESCs to type II pneumocytes.     

Virus-inhibiting surgical glove to reduce the risk of infection by enveloped viruses

Needle puncture and other accidents that occur during surgery and other procedures may lead to viral infections of medical personnel, notably by hepatitis C (HCV) and human immunodeficiency virus (HIV), now that hepatitis B can be prevented by vaccination. A new surgical glove called G-VIR, which contains a disinfecting agent for enveloped viruses, has been developed. Herpes simplex type 1 (HSV) was used as a standard enveloped virus in both in vitro and in vivo tests of the virucidal capacity of the glove. Bovine viral diarrhea virus (BVDV) and feline immunodeficiency virus (FIV) were used as models for HCV and HIV, respectively. For in vitro study, a contaminated needle was passed through a glove and residual virus was titrated; for in vivo studies, animals were stuck with a contaminated needle through a glove. Despite variation in virus enumeration inherent in the puncture technique, statistical evaluation showed that infection was reproducibly and substantially reduced by passage through the virucidal layer. For BVDV, the amount of virus passing through the virucidal glove was reduced in 82% of pairwise comparisons with control gloves that lacked the virucidal agent; when plaque counts were adjusted to a common dilution, the median count for the virucidal glove was on the average reduced >10-fold. In experiments in which the proportion of wells infected with FIV was measured, the ratio of TCID(50) values (control glove to G-VIR) was >15, and probably much higher. For HSV, the amount of virus passing through the virucidal glove was reduced in 81% of comparisons with control gloves; the median of adjusted plaque counts was reduced on the average approximately eightfold or ninefold. In vivo tests with FIV and HSV in cats and mice, respectively, found smaller percentage reductions in infection than the in vitro tests but confirmed the virucidal effect of the gloves.     

Minicircular DNA having sequence homologies with chloroplast DNA in a bleached mutant of Euglena gracilis

Summary Chloroplast DNA was isolated from total cellular DNA of a bleached mutant of Euglena gracilis (Y₃BUD) by enrichment of the light component (p = 1.686) by repeated CsCl equilibrium centrifugations. Electron microscope visualization of this DNA showed minicircular DNA molecules in addition to large circular molecules (42 pm) identical to wild type chloroplast DNA. They were heterogenous in size and their contour lengths ranged from 0.8 to 8.5 m. Fractionnation by agarose gel electrophoresis gave several discrete bands. Some of them hybridized with pure chloroplast DNA and with several cloned chloroplast DNA fragments, particularly to ribosomal fragments, while others did not show homology with chloroplast DNA being probably of extrachloroplatic origin.     

Effects of interleukin 4 on CD25+CD4+ regulatory T cell function

CD25+CD4+ regulatory T cells (Tregs) contribute to the maintenance of peripheral tolerance against self and non-self. The modulatory effects of cytokines, such as interleukin 4 (IL-4) on the function of Tregs have not been explored in detail. We here report that IL-4 prevents spontaneous apoptosis and the decline of foxp3 mRNA which were found to occur during culture of isolated Tregs. Tregs exposed to IL-4 were more potent in suppressing the proliferation of na?ve CD4+ T cells and they better inhibited IFN-gamma production by CD4+ T cells as compared to Tregs cultured in medium. IL-4 also enhanced membrane IL-2Ralpha (CD25) expression on Tregs above the levels observed on freshly isolated cells. IL-4-mediated effects on Treg function persisted in Tregs from Stat6-/- mice, pointing to a Stat6-independent intracellular transduction pathway. In conclusion, our data suggest that the anti-inflammatory function of IL-4 could partly be mediated by effects on Tregs function.