Proterozoic microbial mats and their constraints on environments of silicification.

The occurrence of microfossiliferous, early diagenetic chert in Proterozoic successions is broadly restricted to peritidal marine environments. Such coastal environments are amongst the most environmentally variable of marine environments, experiencing both enhanced evaporation and potential influx of terrestrial freshwaters. To better understand potential conditions under which silicification occurs, we focus on microfossiliferous early diagenetic chert from the Mesoproterozoic Bylot Supergroup, northern Baffin Island. Spectacular preservation of silicified microbial mats, their associated mineral phases, and the petrographic fabrics of the chert itself require that silicification occurred at the sediment-water interface, penecontemporaneously with mat growth. In some cases, silica is the primary precipitated mineral phase and is not associated with replacement of precursor mineral phases. In other cases, silica deposition includes the mimetic replacement of carbonate, gypsum, and halite mineral phases. These petrographic constraints suggest that silicification potentially occurred under a range of fluid chemistries associated with environmental variability in nearshore peritidal environments. Here we provide the first direct thermodynamic modeling of hypothetical Proterozoic seawater solutions, seawater-derived brines, and mixed seawater-freshwater solutions, and demonstrate that peritidal environments are capable of providing a wide range of fluid chemistries under which early diagenetic silica can both precipitate and replace primary mineralogical phases. Despite the thermodynamic potential for silica deposition under a wide range of fluid compositions, chert is not ubiquitous in Proterozoic nearshore environments, suggesting that the kinetics of silica polymerization exert a primary control over deposition.

[The association of risk of development of cardiomyopathies with polymorphic variants of genes of angiotensin converting enzyme, glutathione-S-transferase, interleukins 8 and 10].

The article presents the results of study of association of risk of development and clinical course of cardiomyopathies with polymorphic variants of genes ACE, GSTM1, IL8 and IL10. The purpose of research was to find out molecular genetic markers of risk of development and clinical course of various types of cardiomyopathies. The analysis used the DNA samples extracted from lymphocytes of peripheral venous blood of patients with cardiomyopathies (N = 89) and control group (N = 426). The standard analysis techniques of polymerase chain reaction and restriction fragment length polymorphism were applied to detect polymorphic loci of genes candidates. It is established that genotype of DD-polymorphic locus of I/DgeneACE is a marker of development of ischemic cardiomyopathy. The allele D is a marker of development of increased rate of manifestation of extra-systoles, growth of inter-ventricular septum and reduction of fraction of discharge in patients with cardiomyopathies.

Lymphoplasmacytic lymphoma. Report of a case with three monoclonal proteins derived from a single neoplastic clone.

The unique case of a 60-year-old patient with a non-Hodgkin's B-cell lymphoma of the lymphoplasmacytic type and three associated monoclonal proteins, is described. The patient also exhibited various autoimmune phenomena that were consistent with the diagnoses of Sjögren's syndrome and autoimmune thyroiditis. The evolution from production of a single monoclonal protein (IgM-kappa) to three monoclonal proteins (IgG-kappa, IgA-kappa, and IgM-kappa) suggested that the lymphoplasmacytic cells were at different stages of terminal differentiation within a single neoplastic clone. The chronic antigenic stress imposed on the immune system by the autoimmune disorder may have played a role in the development of lymphoma and in the heavy chain immunoglobulin switching that occurred during the patients' clinical course.

The undifferentiated malignant neoplasm. Identification of lymphoma arising in skeletal muscle by immunohistochemical analysis.

The undifferentiated malignant neoplasm presents a significant problem in the intelligent selection of therapy. Because of advances in chemotherapy, there are cancers that are effectively palliated, and sometimes cured if appropriately treated. Characterization of tumors by immunohistochemical stains drastically reduces the incidence of "undifferentiated" diagnoses and will optimize patient management, as illustrated by two cases of large-cell lymphoma arising in skeletal muscle.