The Effect of Liquid Slurry-Enhanced Corrosion on the Phase Composition of Selected Portland Cement Pastes

This paper presents the scientific problem of the biological corrosion of Portland cements and its effects on the phase composition of cement pastes after the corrosion process in the environment of reactive media from the agricultural industry. Seven Portland cements produced from different cement plants exposed to pig slurry and water as a reference medium for a period of six weeks were tested. After the exposure process in both of the above-mentioned reaction environments, the hydrating cement pastes were characterized in terms of their phase composition using the XRD method and were also subjected to morphological observations and a chemical composition analysis with the application of SEM and EDS methods. The results of these studies indicate the presence of a biological corrosion product in the form of taumasite [C₃S·CO₂·SO₃·15H₂O], which is a phase formed as a result of the reaction of dead matter (cement paste) with living matter, caused by the presence of bacteria in pig slurry. In addition to taumasite, the tested samples also showed the presence of the hydration product of Portland cements named portlandite (Ca(OH)₂). Moreover, unreacted phases of cement clinker, i.e., dicalcium silicate (C₂S) and tricalcium aluminate (C₃A), were detected. Based on microscopic observations and analyses of the chemical composition of selected areas of the samples, the presence of the taumasite phase and compact areas of pseudo-crystalline C-S-H phases with different morphological structures, derived from the hydration products of cements doped with ions originating from the corrosive environment, were confirmed.     

The Osteopathic Applicant

The number of osteopathic students choosing emergency medicine (EM) as a specialty is continuously increasing. However, EM remains a competitive specialty. Accordingly, in this article we guide osteopathic students interested in EM through the Comprehensive Osteopathic Medical Licensing Examination (COMLEX), the United States Medical Licensing Examination (USMLE), third- and fourth-year rotations, and the match process. Additionally, we provide tips on the process of applying to allopathic programs and we discuss the timeline of both the allopathic and osteopathic match. Finally, we discuss the effect of the Single Accreditation System and the Memorandum of Understanding, an agreement to merge the allopathic and osteopathic graduate medical education systems into a single graduate medical education accreditation system. This is expected to be completed as of July 1, 2020. Therefore, we elucidate the expectations for osteopathic applicants (particularly with regards to the USMLE and COMLEX examinations).     

Expression and function of a receptor for hyaluronan-mediated motility on normal and malignant B lymphocytes

Migration through extracellular matrix is fundamental to malignant invasion. A receptor for hyaluronan-mediated motility (RHAMM) has previously been shown to play a fundamental role in locomotion of ras- transformed cells as well as functioning in signal transduction. Expression of RHAMM was characterized on B lymphocytes from normal and malignant lymphoid tissues using multiparameter phenotypic immunofluorescence analysis as well as functional analysis of its role in locomotion of malignant hairy cell leukemia B cells. RHAMM is not detectable on most normal B cells located in blood, spleen, or lymph node, but it is detectable on bone marrow and thymic B cells. Among B- cell malignancies, it is expressed on most terminally differentiated B cells from multiple myeloma bone marrows, is present on a subset of non- Hodgkin's lymphomas, and is absent on B chronic lymphocytic leukemia. Activation of peripheral blood B cells by Staphylococcus A cowan (SAC), but not by pokeweed mitogen, induced transient expression of RHAMM at day 3 of culture, suggesting RHAMM may be used by antigen-activated normal B cells. For malignant cells, expression of RHAMM increased on long-term culture of bone marrow plasma cells from multiple myeloma patients, indicating prolonged expression in contrast to the transient expression on SAC-activated normal B cells. Intriguingly, RHAMM was expressed on hairy leukemia cells located in spleen but absent from those in peripheral blood of the same patient. RHAMM, as expressed on splenic hairy cells, was a 58-Kd molecule that binds hyaluronan, is encoded by a 5.2-kb messenger RNA, and participates in locomotion by these cells. Hairy cells locomoted in response to hyaluronan at 4 mu per minute. Monoclonal antibody to RHAMM inhibited this locomotion almost completely as detected using video time-lapse cinemicrography. These observations are consistent with a role for RHAMM in malignant invasion and metastatic growth.     

Effect of Alkaloid-Free and Alkaloid-Rich preparations from Uncaria tomentosa bark on mitotic activity and chromosome morphology evaluated by Allium Test

Ethnopharmacological revelance

Uncaria tomentosa (Willd.) DC. is the most popular Peruvian plant, used in folk medicine for different purposes. It contains thousands of active compounds with great content of alkaloids.

Aim of study

Two different fractions of Alkaloid-Rich and Alkaloid-Free were researched on chromosome morphology, mitotic activity and phases indexes.

Materials and methods

Cells of Allium Test (meristematic cells of root tips) were incubated up to 24 h in different concentrations of Alkaloid-Free and Alkaloid-Rich fraction obtained from Uncaria tomentosa bark followed by 48 h of postincubation in water. The chromosome morphology was analyzed and the content of mitotic and phase indexes were done. Individual compounds, oxindole alkaloids, phenolic compounds and sugars were determined.

Results

In Alkaloid-Rich and Alkaloid-Free fractions (different in chemical composition) we observed condensation and contraction of chromosomes (more in Alkaloid-Rich) with retardation and/or inhibition of mitoses and changed mitotic phases. Postincubation reversed results in the highest concentration which was lethal (in mostly Alkaloid-Rich fraction).

Conclusions

Our studies indicate that different action can depend on different groups of active compounds in a preparation either containing alkaloids or not. Other fraction analysis may be useful in the future.     

Antigen-specific suppression of cytotoxic T cell responses in mice. I. Suppressor T cells are not cytotoxic cells.

The main conclusion from these experiments is that the antigen-specific suppressor T cell of mice which inhibits the induction of cytotoxic T lymphocytes is not itself a cytotoxic T cell. This conclusion is supported by two main observations: first, a certain cell number from first-step cultures which was suppressive in the presence of a high dose of antigen actually helped the cytotoxic response at a lower antigen dose. This observation is difficult to reconcile with the hypothesis that suppression is due to the killing of the stimulator or the responder cells in the second-step culture by cytotoxic T cells. Second, cells from first-step cultures of cortisone-treated mice displayed cytotoxic activity but had no suppressive effect on the generation of killer cells. It was further demonstrated that these cells failed to influence in any way the suppressive effect, however weak, of cells from first-step cultures of normal spleen. We therefore favor the view that the suppression observed in this system is due to a regulatory signal which occurs as a result of the ability of both inhibitory cells and responder cells to recognize and respond to allogeneic determinants expressed on the surface of stimulator cells. The suppressor T cells described here act by linked associative recognition of antigen. That is, suppressor T cells only inhibit the induction of a precursor cytotoxic T cell in the presence of an antigen to which both the precursor cell and the suppressor cell can bind. In this sense, suppressors act in a manner analogous to helper T cells in T-B cell cooperation; carrier-specific helper T cells only enhance an anti-hapten B cell response in the presence of hapten-carrier conjugates. Similarly, alloantigen a (carrier)-specific suppressor T cells only inhibit alloantigen b (hapten)-specific cytotoxic responses in the presence of (a × b)F₁ stimulator cells (hapten-carrier conjugate), not in the presence of a mixture of parental stimulator cells (a + b).     

Charakterisierung von Strukturelementen in den Lipopolysacchariden von Pasteurella multocida

In the main fraction of oligosaccharides obtained after the acetic acid hydrolysis of the lipopolysaccharides of the strain PM were identified: terminal bound glucose and L-glycero-D-mannoheptose, 1,2-,1,3,4-, and 1,3,4,6,-linked heptose. The oligosaccharide of the strain 1297 S contains terminal linked galactose, 1,4- or 1,6-linked glucose and 1,4-linked N-acetylglucosamine additionally. The molar ratios of these elements show the heterogenicity of the preparations. The determined molecular weights underline the R-character of the LPS In the by-fractions of the acetic acid hydrolysis the known mannan and another polysaccharide with galactose and glucosamine were identified.     

Karsch-Neugebauer syndrome: split foot/split hand and congenital nystagmus

A family with four members with split foot/split hand malformations and congenital nystagmus is described. The clinical characteristics in this family correspond to those seen in two other families previously reported. Taken together, these three families suggest that a single, pleiotropic dominant gene is causal. Karsch-Neugebauer syndrome is suggested as an appropriate eponymic designation for this disorder.