Molecular evidence for the expression of nicotinic acetylcholine receptor alpha-chain in mouse thymus.

The presence and structure of nicotinic acetylcholine receptor (nAChR) in the thymus has been a subject of interest for many years because of its possible role in the pathogenesis of the autoimmune disease myasthenia gravis. Using the polymerase chain reaction with primers specific for the alpha-chain of nAChR (nAChR-alpha), an 880-bp homologous band was found after amplification of cDNA prepared from mouse thymus, thymic medullary and cortical epithelial cell lines, but not from thymocytes or kidney. Sequencing of the polymerase chain reaction product from the thymus and thymic medullary and cortical epithelial lines showed identity with skeletal muscle nAChR-alpha over the region examined. This region includes the domains of the molecule on which B cell and T cell autoantigenic targets have been described. No evidence was found in mouse tissue for the exon 3A, which has been described in human muscle and the human rhabdomyosarcoma cell line TE671. Our results provide evidence at the RNA level for the expression of the nAChR-alpha on stromal cells but not on thymocytes in normal murine thymus and are consistent with a role for intrathymic autoantigen expression in the pathogenesis of myasthenia gravis.     

The Functional Repertoire of Survivin's Tails

Survivin is a multitasking protein that can inhibit cell death and that is essential for mitosis. Due to these prosurvival activities and the correlation of its expression with tumor resistance to conventional cancer treatments, survivin has received much attention as a potential oncotherapeutic target. Nevertheless, many questions regarding its exact role at the molecular level remain to be elucidated. In this study we ask whether the extreme C- and NH₂ termini of survivin are required for it to carry out its cytoprotective and mitotic duties. When assayed for their ability to act as a cytoprotectant, both survivin_1–120 and survivin_11–142 were able to protect cells against TRAIL-mediated apoptosis, but when challenged with irradiation cells expressing survivin_11–142 had no survival advantage. During mitosis, however, removing the NH₂ terminal 10 amino acids (survivin_11–142) had no apparent effect but truncating 22 amino acids from the C-terminus (survivin_1–120) prevented survivin from transferring to the midzone microtubules during anaphase. Collectively the data herein presented suggest that the C-terminus is required for cell division, and that the NH₂ terminus is dispensable for apoptosis and mitosis but required for protection from irradiation.     

Hyperthermic treatment of chromomycosis with disposable chemical pocket warmers

A case of chromomycosis in which hyperthermia proved effective is reported. The patient was a 56-year-old male bean curd maker who, without any previous history of minor trauma, developed on the extensor side of the left upper arm an eczematous lesion that underwent gradual radial expansion. The lesion showed a well-defined, 7×10 cm infiltrated erythematous plaque with the central area healed and, at the upper and lower borders, adherent scales and crusts on the surface. Histological examination revealed granulomatous changes in the dermis, as well as sclerotic cells within giant cells and microabscesses. On culturing,Fonsecaea pedrosoi was isolated. The patient was treated with disposable chemical pocket warmers, which were secured over the lesion with a rather tight elastic bandage, so that they kept the affected area warm for 24 hours a day. After a month of such hyperthermic treatment, the erythema and infiltration had decreased considerably, and microscopic examination and culture of the crusts both yielded negative results. Examination of biopsy specimens of the lesion after the third month showed that it had cicatrized. The treatment was stopped after 4 months, and no relapse occurred. We also summarize the published results of local hyperthermic treatment of chromomycosis in Japan.     

Investigation of the mechanism of protein turnover in HeLa S-3 cells by incubation at elevated temperatures

An apparent paradox relating to the degradation of endogenous proteins in HeLa S-3 cells occurs at 45 degrees C, at which their proteolysis is considerably enhanced in vitro but completely inhibited in vivo. No significant differences in rates of degradation of short-lived (nascent) and long-lived ('existing') proteins synthesised at 37 degrees C were found when chased at temperatures up to 43 degrees C, but at 45 degrees C degradation of both categories was reduced to zero in vivo. Synthesis of protein was suppressed at temperatures above 41 degrees C, being reduced by up to 60% at 43 degrees C. Proteolysis in vitro proceeded 1.6-1.7 times faster at 45 degrees C than at 37 degrees C and neutral pH. Evidence is presented for the involvement of the basal system; the findings both in vivo and in vitro do not seem to implicate the lysosomal system, no firm indication being obtained of its 'induction' at elevated temperatures. The results are discussed in terms of the arrest of intracellular circulation at elevated temperatures, thereby reducing the delivery rate of proteins as substrates of the intracellular basal proteolytic enzyme system to negligible levels (i.e., to the frequency of encounters due solely to the diffusion of protein molecules with the cytoplasm).     

Identification of HLA-B44 subtypes associated with extended MHC haplotypes

The HLA class I antigen B44 is found in each of two different extended major histocompatibility haplotypes (allele combinations of HLA-B, HLA-DR, and complement genes BF, C2, C4A, and C4B in linkage disequilibrium). Using isoelectric focusing, two variants of HLA-B44 were identified. The basic variant was found in all cell lines with the extended haplotype HLA-B44, DR7, FC31, and the acidic variant in all cell lines with the extended haplotype HLA-B44, DR4, SC30. The occurrence of each antigen variant with a unique extended haplotype explains previous observations concerning the nonrandom association of B44 variants with DR antigens.     

Randomised trial of prophylactic daily aspirin in British male doctors

A six year randomised trial was conducted among 5139 apparently healthy male doctors to see whether 500 mg aspirin daily would reduce the incidence of and mortality from stroke, myocardial infarction, or other vascular conditions. Though total mortality was 10% lower in the treated than control group, this difference was not statistically significant and chiefly involved diseases other than stroke or myocardial infarction. Likewise, there was no significant difference in the incidence of non-fatal myocardial infarction or stroke—indeed, disabling strokes were somewhat commoner among those allocated aspirin. The lower confidence limit for the effect of aspirin on non-fatal stroke or myocardial infarction, however, was a substantial 25% reduction. Migraine and certain types of musculoskeletal pain were reported significantly less often in the treated than control group, but as the control group was not given a placebo the relevance of these findings was difficult to assess. There was no apparent reduction in the incidence of cataract in the treated group.The lack of any apparent reduction in disabling stroke or vascular death contrasts with the established value of antiplatelet treatment after occlusive vascular disease.     

Pulmonary paracoccidioidomycosis in immunized mice

Paracoccidioidomycosis was induced in immunized (IM) and non-immunized (NI) mice. The histopathology, the number of fungi in the lungs, the cellular (footpad test — FPT and macrophage inhibition factor assay — MIF) and humoral (immunodiffusion test) immune response were investigated serially postinfection. In the IM mice, at days 1 and 3, there was intense and predominant macrophagic-lymphocytic alveolitis with loose granulomatous reaction; at day 30, inflammation was mild. In the NI group, up to day 3, the lesions were focal; later there was formation of extensive epithelioid granuloma. The number of fungi in IM mice were always smaller than those of NI group. Immunization alone induced positive FPT and MIF indices with low titer of antibody. After infection, there was a significant decrease of the FPT indices in the IM group, which we interpreted as desensitization due to trapping of sensitized lymphocytes in the lungs. In conclusion, (1) The lesional pattern of pulmonary paracoccidioidomycosis in IM mice was similar to that of a hypersensitivity pneumonitis. This reaction was probably effective in reducing the extension of the infection and decrease the number of fungi. (2) In this model, pulmonary resistance against P. brasiliensis seems to be related to local and systemic delayed-type hypersensitivity reaction.     

Comparative effects of a recombinant and a mutein type of granulocyte colony stimulating factor on the growth of Meth-A fibrosarcoma with 5-fluorouracil chemotherapy

The present study was designed to evaluate the effects of a recombinant human G-CSF (rhG-CSF) and a mutein G-CSF(KW-2228) on leucopenia and tumor growth in mice treated with 5-fluorouracil (5-FU). In normal mice, the number of leucocytes (white blood cell, WBC) reached the peak 12 hours after a single injection of either type of G-CSF and decreased to the normal level after 24 hours. Daily administration induced a continuous increase in the WBC count, however, administrations at intervals did not. Meth-A fibrosarcoma was subcutaneously inoculated into the backs of syngeneic BALB/c mice. The mice were treated with 5-FU alone or with G-CSFs. Chemotherapy with 5-FU alone resulted in leucopenia and an insignificant inhibition of tumor growth. The conjunctive administration of G-CSFs with 5-FU resulted in a significantly augmented inhibition of tumor growth, and leukopenia was not seen. This augmenting effect was more prominent with KW-2228.These results suggest that in 5-FU chemotherapy G-CSFs may be beneficial in restoring the number of leucocytes from leucopenic state and in augmenting the tumor inhibitory effect. Furthermore, KW-2228 may be more beneficial than the natural type rhG-CSF.