大面积皮肤坏死患者的临床分析

目的探讨大面积皮肤坏死的诱因、治疗和危害。方法对1998年1月至2008年1月收治的36例患者大面积皮肤坏死的情况进行调查分析。结果大面积皮肤坏死引起肢体功能障碍15例,部分功能障碍19例,无功能障碍2例。结论大面积皮肤坏死与皮肤撕脱,厌氧菌和需氧菌混合感染,其他继发疾患引起有关,应采取积极治疗措施,提高患者生存质量。     

Coumarin induced acral skin necrosis associated with hereditary protein C deficiency

Hemorrhagic skin necrosis of the toes was observed in a patient with heterozygous protein C deficiency (protein C:Ag 32% and protein C activity 30%) on the 4th day of coumarin treatment overlapping with effective intravenous anticoagulation with heparin. Family studies revealed protein C deficiency in two sisters of the proposita without a history of thromboembolic disease. Immunologic studies in the proposita at the time of coumarin necrosis revealed slight depression of complement factor C4 and the presence of immune complexes. The present case and review of the literature show that the pathogenetic mechanism leading to coumarin necrosis in patients with protein C deficiency seems not yet to be fully understood.     

Electrochemical antigen-retrieval of formaldehyde fixed and paraffin-embeddedarchived leprosy skin biopsies

Summary While formaldehyde fixation preserves tissue morphology, it often hinders immunodetection of antigens in paraffin-embedded tissue because the antigens are masked. Antigen unmasking can be achieved with treatments such as microwave irradiation but they often lead to excessive tissue damage. Therefore, an electrochemical antigen-retrieval method (EAR) was devised in which an alternating electric current is passed through the tissue in a chamber containing an electrolyte buffer. The results obtained with this method were compared to those after microwave irradiation using archived samples of formaldehyde-fixed and paraffin-embedded lepromatous leprosy skin. The efficacy of the two unmasking procedures was assessed by the immunodetectability of several marker antigens using 24 antibodies. Fifteen antibodies that were directed against transmembrane proteins (CD), and the remaining 9 against cytokeratins 18.6 and 19, laminin, vimentin, S100a, BCG,Ulex europaeus lectin, PCNA, and P21^ras. Simple and double immunohistochemistry was performed using the universal ENVISION and LSAB + AP detection systems. After unmasking with the EAR method, immunoreactivity was clearly detected with 22 of the 24 antibodies in single labeling reactions. They include the critical antigens CD3 and CD4 for identifying the T lymphocyte lineages. In contrast, only 20 of the antibodies reacted after microwave irradiation. After double immunolabeling, immunoreactivity was quantitatively similar with both methods. However, the EAR unmasking produced a stronger labeling reaction. Thus, with double labeling immunohistochemistry, EAR made it possible to use higher antibody dilutions and shorter incubation times. Heat damage was also prevented. In conclusion, EAR treatment produces better staining results than microwave irradiation treatment.     

Critical temperature for skin necrosis in experimental cryosurgery

To investigate the minimal lethal freezing temperature required to produce skin necrosis in dogs, multiple skin sites were frozen with cryosurgical equipment. Tissue temperatures were recorded from thermocouple sites placed at diverse distances, usually 5 mm from the edge of the freezing probe. In single freezing cycles of about 3 min duration, tissue temperatures in the range of 0 to ?60 °C were produced. Punch biopsies of the skin at the thermocouple sites 3 days after freezing injury provided tissues for estimation of viability by histologic examination.The histologic findings permitted classification of the biopsy tissue into three groups, that is, viable, borderline, or necrotic. When classified as borderline, the division between the necrotic and viable tissue was evident on the histologic slide. The viable specimens were scattered through the 0 to ?35 °C range. All specimens frozen to ?10 °C or warmer were viable. In biopsies classified as borderline, the range of viability extended from ?11 ° to ?50 °C. The necrotic biopsies covered a range of ?14 ° to ?50 °C. Cell death was certain at temperatures colder than ?50 °C. The data showed cryosurgical freezing conditions produced a range of temperatures in which viability or death of tissue may occur and that the ranges of viability and necrosis overlapped to a great extent.The wide range of temperatures at which cells were viable shows the need to achieve tissue temperatures in the range of ?50 °C in the cryosurgical treatment of cancer.     

Prevention of skin flap necrosis by a course of treatment with vasodilator drugs.

Large island skin flaps, comprising the entire abdominal covering in rats, were raised on one neurovascular pedicle in the groin. A standard area of necrosis was produced on the other side from the pedicle. However, when the animals were treated with certain vasodilator drugs for 15 days before and 7 days after the flaps were raised, there was little or no necrosis. The effect of the drug therapy was the same as a surgical delay.     

Intravital microscopy demonstrating antibody-mediated immobilisation of Plasmodium berghei sporozoites injected into skin by mosquitoes

Previous studies have shown that mosquitoes inject Plasmodium sporozoites into avascular portions of the skin of their rodent host rather than directly into the blood circulation. Then, over time, these sporozoites move into the circulation, from where they reach the liver to initiate a malaria infection. By use of intravital microscopy of the skin, we present direct morphological evidence of mosquito probing that introduces sporozoites into avascular tissue, of the migration of these sporozoites through the dermis and into blood vessels, and of the role of anti-sporozoite antibodies in blocking sporozoite invasion of these dermal blood vessels.     

Reaction of formaldehyde with calf-thymus nucleohistone

The reactions of formaldehyde with calf thymus nucleohistone were analyzed in the following ways: measurement with fluorescamine of the decrease in primary amino groups resulting from hydroxymethylation and crosslinking reactions, measurement with dodecylsulphate-gel electrophoresis of formation of histone oligomers, measurement of fixation of histones to the DNA in nucleohistone, and measurement of changes in the circular dichroism spectrum in the region of 250--300 nm. In the presence of formaldehyde, the primary amino groups of histones decreased very rapidly, attaining an equilibrium within 60 min, and successively intermolecular crosslinks were also formed between histone molecules, the resulting dimers and oligomers being separable by dodecylsulfate-gel electrophoresis. Whereas the fixation reaction proceeded much more slowly. The extent of fixation could be measured more accurately by dodecylsulfate/sucrose centrifugation analysis than by sulfuric acid extraction. After removal of formaldehyde from the reaction mixture, the fraction of masked amino groups decreased, perhaps due to the reverse reaction, but the extent of fixation of histones continued to increase with time. No specificity was observed among five molecular species of histones in the fixation reaction. With increase in formaldehyde concentration, the ellipticity of nucleohistone decreased to a minimum with about 0.4% formaldehyde, and then increased.     

Microbiota induces expression of tumor necrosis factor in postnatal mouse skin

Tumor necrosis factor (TNF) is a pleiotropic cytokine that regulates many important processes in the body. TNF production in a physiological state supports the structure of lymphoid organs and determines the development of lymphoid cells in hematopoiesis. However, chronic TNF overexpression leads to the development of various autoimmune disorders. Sites of TNF production in the naive state remain unclear due to the lack of in vivo models. In the present study, we used TNF-2A-Kat reporter mice to monitor the expression of TNF in different tissues. Comparative analysis of tissue fluorescence in TNF-2A-Kat reporter mice and wild type mice revealed constitutive expression of TNF in the skin of naive adult mice. In the skin of TNF-2A-Kat reporter mouse embryos, no statistically significant differences in the expression of TNF compared to wild type animals were observed. Furthermore, we established that local depletion of microflora with topical antibiotics leads to a reduction in the fluorescence signal. Thus, we assume that the skin microflora is responsible for the expression of TNF in the skin of mice.