Macromolecules of the central nervous system and acoustic priming in C57BL/6Bg mice

Short-term cultures of androgen-responsive Shionogi 115 (S115) cells exhibited density-dependent regulation of proliferation rate in the presence or absence of testosterone. The average surface area per cell exposed to the growth medium was inversely proportional to population density. By contrast, long-term cultures (serially passaged in testosterone-containing medium for several months) did not exhibit density-dependent regulation of proliferation rate when grown in testosterone-containing medium. In this medium, cells became elongated and no longer exhibited any obvious decrease in exposed surface area with increasing density. Nevertheless, when subcultured into testosterone-free medium, these cells reverted to an epithelial morphology and exhibited density-dependent regulation of proliferation rate. These relationships suggested that the proliferation rate of cells decreased with density in proportion to the decrease in exposed surface area...     

Fibrin regulates neutrophil migration in response to interleukin 8, leukotriene B4, tumor necrosis factor, and formyl-methionyl-leucyl-phenylalanine

We have examined the capacity of four different chemoattractants/cytokines to promote directed migration of polymorphonuclear leukocytes (PMN) through three-dimensional gels composed of extracellular matrix proteins. About 20% of PMN migrated through fibrin gels and plasma clots in response to a gradient of interleukin 8 (IL-8) or leukotriene B4 (LTB4). In contrast, < 0.3% of PMN migrated through fibrin gels in response to a gradient of tumor necrosis factor alpha (TNF) or formyl-methionyl-leucyl-phenylalanine (FMLP). All four chemoattractants stimulated PMN to migrate through gels composed of collagen IV or of basement membrane proteins (Matrigel), or through filters to which fibronectin or fibrinogen had been adsorbed. PMN stimulated with TNF or FMLP adhered and formed zones of close apposition to fibrin, as measured by the exclusion of a 10-kD rhodamine-polyethylene glycol probe from the contact zones between PMN and the underlying fibrin gel. By this measure, IL-8- or LTB4-treated PMN adhered loosely to fibrin, since 10 kD rhodamine-polyethylene glycol permeated into the contact zones between these cells and the underlying fibrin gel. PMN stimulated with FMLP and IL-8, or FMLP and LTB4, exhibited very little migration through fibrin gels, and three times as many of these cells excluded 10 kD rhodamine-polyethylene glycol from their zones of contact with fibrin as PMN stimulated with IL-8 or LTB4 alone. These results show that PMN chemotaxis is regulated by both the nature of the chemoattractant and the composition of the extracellular matrix; they suggest that certain combinations of chemoattractants and matrix proteins may limit leukocyte movements and promote their localization in specific tissues in vivo.     

Detection of clonal platelet antibodies in immunologically-mediated thrombocytopenias: association with circulating clonal/oligoclonal B cells

Aware that T and B cells in autoimmune thrombocytopenia are abnormal, including the existence of clonal B cell populations, we sought to characterize this clonal phenomenon in various immunological thrombocytopenias using platelet antibody light chain analysis, flow cytometry, Southern blot analysis, and PCR. Using a monoclonal antibody-antigen capture ELISA, we analysed sera from 21 of 26 patients with autoimmune, alloimmune, or drug-induced immunological thrombocytopenia for the light chain phenotypes of their platelet antibodies. Alloantibodies and drug-dependent antibodies from four and 14 patients, respectively, were found that expressed a predominant type of light chain, suggesting that these platelet-reactive antibodies were monoclonal or oligoclonal in nature. 14 of the 26 patients were available for light chain B cell phenotyping studies. Of these 14 patients, thrombocytopenia was due to autoimmunity in two, drug-induced immunity in four, and alloimmunity in eight. We detected clonal populations of B cells in all 14 patients by flow cytometry. Although six of these latter patients possessed platelet antibodies with clonal characteristics, light chain phenotypes of antibodies in five patients were opposite to those of their B cells. Eight of these patients were further examined for immunoglobulin gene rearrangement using Southern and/or polymerase chain reaction analysis. In all eight patients we detected clonal or oligoclonal B cell populations. Only two of these patients had malignancies (chronic lymphocytic leukaemia) that would be expected to have detectable clonal B cells, and thus the mechanism for clonal expansion in the other six patients did not appear to be related to an obvious neoplastic process. Prior to these studies, detection of clonal B cells in thrombocytopenic patients without known malignancies was limited to individuals with autoimmune thrombocytopenia, prompting the speculation that this particular autoimmune disorder arises from B cell dysregulation, rather than from expansion of specific autoantibody producing B cell clones. In contrast, the current studies provide evidence that clonal B cells are common to patients with any form of immunologically-mediated thrombocytopenia. Moreover, the majority of the platelet antibodies (86%) present in these disorders exhibited monoclonal characteristics in that there was an apparent restriction in light chain usage.     

Leishmania mexicana: proteinase activities and megasomes in axenically cultivated amastigote-like forms

Proteinase activities and megasomes were examined in axenically cultivated amastigote-like forms, freshly isolated lesion amastigotes, and promastigotes. Megasomes were absent in promastigotes and present in both amastigote stages, but they seemed to be less numerous and more homogeneous in cultured amastigote-like forms. Contrasting with the poor detection of proteinase activities in promastigote lysates, both types of amastigotes shared multiple proteinases, which were classified in two groups: (a) 60 to > 100 kDa, o-phenanthroline-sensitive activities; and (b) 23- to 40-kDa cysteine proteinases, of which those resolving as 35- to 40-kDa bands in gelatin gels were more clearly visualized in lysates of cultured amastigote-like forms. Incubation of both kinds of amastigotes with 0.25 to 1.0 microM of either Z-Phe-AlaCHN2 or Z-Tyr-AlaCHN2 selectively inactivated cysteine proteinases, but not the 35- to 40-kDa activities, which, again, were detected with higher intensity in cultured amastigote-like forms. The expression of the 35- to 40-kDa proteinases progressively increased when promastigotes were allowed to transform into amastigote-like forms or when lesion amastigotes were incubated at 34 degrees C for different time periods prior to exposure to Z-Phe-AlaCHN2; activities comparable to those of amastigote-like forms were attained within 24 to 48 hr. The activities resistant to Z-Phe-AlaCHN2 in vivo were fully inhibited by E-64 or Z-Phe-AlaCHN2 during gelatin digestion, suggesting that the 35- to 40-kDa proteinases were mainly inactive before cell lysis. The presence of cycloheximide (at 10, 50, and 100 micrograms/ml) during the pulse with Z-Phe-AlaCHN2 abolished the 35- to 40-kDa activities of lesion amastigotes and significantly reduced gelatin digestion by the similar enzymes of cultured amastigote-like forms. In the latter, the 35- to 40-kDa proteinases were no more detected when cycloheximide was given 60 min prior to Z-Phe-AlaCHN2. The results indicate higher rates of synthesis of the 35- to 40-kDa enzymes, and the existence of a more representative pool of inactive enzyme precursors, in cultured amastigote-like forms.     

Potential for an external vaginal antiitch cream containing benzocaine to cause methemoglobinemia in healthy women

OBJECTIVES: Our purpose was to assess the potential for an external vaginal antiitch cream (20% benzocaine, 3% resorcinol) to significantly increase levels of methemoglobin above normal in healthy women. STUDY DESIGN: Fifty-five women reporting external vaginal itch were recruited for the study. Each patient was used as her own control with methemoglobin levels being measured before and after use of the cream. Women were instructed to apply a 1-inch strip of cream by fingertip to the external genital area three or four times a day for 7 consecutive days. RESULTS: There were no significant differences in methemoglobin levels before and after use or in levels from a subgroup of women aged > 50 years compared with levels in a younger population. CONCLUSIONS: This preparation appears to be safe when used as directed; however, the results cannot be extrapolated to the very young. Nevertheless, lavish or frequent application over wide areas of excoriation might lead to toxic concentrations and methemoglobinemia. Therefore patients with serious vaginal disease should be advised against self-treatment beyond the 7-day limit imposed by the Food and Drug Administration for over-the-counter external analgesic medications.