Ecologic studies of rodent reservoirs: their relevance for human health

To gain insight into the immunomodulatory effects of vitamin E (VE), immune cell population analyses were conducted using thymus and spleen from male broilers fed diets with various levels of VE supplementation (0, 17, 46, and 87 mg dl-alpha-tocopherol acetate/kg of feed). At 2 and 7 wk of age, the percentages of B cells, macrophages, and T cell subsets, delineated by the expression of CD4, CD8, and T cell receptor (TCR) isotype, in thymus and spleen were determined by flow cytometry. The percentages of thymic and splenic B cells and macrophages from 2- and 7-wk-old chickens, as well as the percentage of thymic T cells in 2-wk-old chickens, were unaffected by VE treatment. However, 7-wk-old broilers maintained on 87 mg VE/kg feed had a higher percentage of CD4+CD8- thymocytes, a higher CD4+CD8- to CD4-CD8+ thymocyte ratio, and a lower percentage of CD4+CD8+ thymocytes than chickens receiving no dietary VE supplementation. The VE-induced increase in the percentage of CD4+CD8- thymocytes was due to an increase in the TCR2+CD4+CD8- thymocyte subset, whereas the decrease in the percentage of CD4+CD8+ thymocytes involved all TCR defined T cell subsets. In the spleen, the percentage of CD4+CD8- T cells was lower in 2-wk-old chickens and higher in 7-wk-old chickens maintained on 87 mg/kg feed than in chickens receiving no dietary VE supplementation. The decrease in CD4+CD8- splenocytes at 2 wk of age was due to a decline in the percentage of TCR2+CD4+CD8- splenocytes, whereas the increase in CD4+CD8- splenocytes in 7-wk-old chicks was due to an increase in the percentages of all TCR defined CD4+CD8- T cell subsets. These data support an immunomodulatory effect of VE on CD4+CD8- T cells.     

The potential relevance of growth hormone to female reproductive physiology and pathophysiology

OBJECTIVE: To assess possible interfacing between the somatotrophic and reproductive axes. DESIGN: Literature review. MAIN OUTCOME MEASURES: Ovarian growth hormone reception and action. RESULTS: The available literature strongly supports a permissive role for the somatotrophic axis in the reproductive process. CONCLUSIONS: Although a role for growth hormone in reproductive biology appears highly likely, its relevance to the process of puberty and to the normal workings of the menstrual cycle, as well as its possible application in reproductive pathology must await further investigation.     

Structures of personality and their relevance to psychopathology.

Trait concepts are used extensively in psychopathology research, but much of this research has failed to consider recent advances in the dimensional structure of personality. Many investigators have discounted the importance of this structural research, arguing that (1) little progress has been made in this area, (2) structural models have little direct relevance for psychopathology research, and (3) the principal methodological tool of structural research, factor analysis, is too subjective to yield psychologically meaningful results. The authors dispute each of these objections. Specifically, an integrative hierarchical model is offered, composed of 4 higher order traits, which is congruent with each of the major structural subtraditions within personality. The implications of this integrative scheme for basic trait research, for the conceptualization and assessment of psychopathology, and for the etiology of disorder are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Morphophysiopathologic studies on the biology of myocardium in acquired valvulopathies

Myocardial lesions due to various valvulopathies were sampled during open heart surgery under extracorporeal circulation, and histologically, histoenzymologically and ultrastructurally investigated. Various cardiomyocitary and interstitial nonspecific progressive lesions, due especially to hemodynamic and hypoxic alterations, were identified. During the pathogenic stages, we remarked the onset and chronic evolution of perivascular and interstitial oedema, enhanced by a reduced lymph draining. The progressive processes of hyalinization, sclerosis and interstitial fibrosis were subsequent to the interstitial matrix modification. These processes accentuate the myocardial hypoxic lesion due to the nutritional and gaseous exchange alterations. The infrastructure, mitochondrial enzyme equipment, sarcoplasma and tubular network lesions, as well as the intramyocitary oedema that destroys the sarcomeric structure, ended with the activation of lysosome and lysosomal enzymes, giving rise to consequent cytolytic foci. Therefore, the process was extending. In this context, we remarked at the electronmicroscopic examination ventricular natriuremic granules, that are rarely mentioned in literature.     

Recent advances in the biology of central nervous system tumors

BACKGROUND: In order to study the biosynthesis of vitamin B12, it is necessary to produce various intermediates along the biosynthetic pathway by enzymic methods. Recently, information on the organisation of the biosynthetic pathway has permitted the selection of the set of enzymes needed to biosynthesise any specific identified intermediate. The aim of the present work was to use recombinant enzymes in reconstituted multi-enzyme systems to biosynthesise particular intermediates. RESULTS: The products of the cobG and cobJ genes from Pseudomonas denitrificans were expressed heterologously in Escherichia coli to afford good levels of activity of the corresponding enzymes, CobG and CobJ. Aerobic incubation of precorrin-3A with the CobG enzyme alone yielded precorrin-3B. When CobJ and S-adenosyl-L-methionine were included in the incubation, the product was precorrin-4. Both precorrin 3B and precorrin-4 are known precursors of vitamin B12 and their availability has allowed new mechanistic studies of enzymic transformations. CONCLUSIONS: Our results show that the expression of the CobG and CobJ enzymes has been successful, thus facilitating the biosynthesis of two precursors of vitamin B12. This lays the foundation for the structure determination of CobG and CobJ as well as future enzymic experiments focusing on later steps of vitamin B12 biosynthesis.     

Break temperatures of mould fluxes and their relevance to continuous casting

Abstract

The break temperatures of mould fluxes are important since they help to control the horizontal heat transfer and lubrication between the steel shell and the mould, and consequently affect occurrences of longitudinal cracking and sticker breakout in continuous casting. Break temperatures T _br have been determined for both steady state and dynamic measurement of the viscosity, and equations relating T _br to chemical composition have been obtained for both cases. It has been found that T _br can be affected by (i) cooling rates and (ii) fluorine losses during the measurements.     

Recent progress in the molecular biology of receptors and intra-cellular signal transduction

Extracellular signals are recognized by the receptors on the surface of cytoplasmic membrane and are transmitted through the complex array of intracellular signal transduction networks. Through recent advances in molecular and genetic analyses, we are beginning to understand the outline of the signaling machineries leading from receptors to targets at molecular level. This review intends to describe the general characteristics of receptors and components of intra-cellular signal transduction systems. Future prospects of the studies on signal transduction in medicine are also discussed.     

Surface properties of the conidiospores of Phanerochaete chrysosporium and their relevance to pellet formation

The conidiospores of the white rot basidiomycete Phanerochaete chrysosporium tend to aggregate during swelling and germination in agitated liquid medium; as time passes, the initial aggregates tend to associate together and to capture conidiospores that remain isolated. The surface chemical compositions of the conidiospores and of developed hyphae were analyzed by X-ray photoelectron spectroscopy. The data were interpreted by modelling the surface in terms of proteins, polysaccharides and hydrocarbonlike compounds. The surface molecular composition of the dormant conidiospores was estimated to be about 45% proteins, 20% carbohydrates, and 35% hydrocarbonlike compounds. There was an increase in the polysaccharide content during germination. Later, when the hyphae were developed, the polysaccharide content became still higher, and the protein content dropped. The initial step of aggregation is attributed to polysaccharide bridging; its occurrence cannot be explained by a change of the overall hydrophobicity or electrical properties of the conidiospores.     

Comparative histological and morphometrical studies into the relevance of intimal thickening to coronary sclerosis

It was found by comparative histological and morphometrical studies, carried out on 125 human hearts of different age (20-90 years) and sex, that there exist critical limiting ranges of intima thickness and the intima/media relationship (IMR) for diffuse intimal thickening and the preatheroma phase of arteriosclerosis. Since furthermore a maximum and a minimum intima thickness as relating to diffuse intimal thickening could be determined, it is assumed that the location and formation of arteriosclerotic plaques is determined by the degree of so-called diffuse intimal thickening. It follows from these findings that postnatal intimal proliferation represents a potential prearteriosclerotic lesion of the intima, and that progressive intimal thickening supports the arteriosclerotic alteration of the intima, leading, through an extensive necrosis of the intima, to the atheroma phase.     

Recent progress in the biology of multiple myeloma and future directions in the treatment

A great amount of scientific information, accumulated over recent years on the biology of Multiple Myeloma (MM), has fuelled speculation about the origin of malignant plasma cells, about a purported critical role played by the bone marrow stroma, and further still, on cytokine interactions and in particular that of IL-6 and its relationship with the immune system. Among the growth factors secreted by stroma cells, IL-6 is a potent stimulator of myeloma cells in vitro but does not induce a malignant phenotype in normal plasma cells. Many efforts have been produced to identify the stem cell in MM and probably memory B lymphocytes are the best candidates. The demonstration of a Graft vs Myeloma effect in the allogeneic setting strongly supports the immunotherapy in MM. Recent data also suggest that a virus (Kaposi-associated herpes virus, HHV-8) may be significantly associated with the development of MM. In parallel, progress has been achieved in the treatment of this incurable disease with well defined prognostic factors, more efficient supportive care and its corollary, improved quality of life and dose-intensified chemo-radiotherapy followed by autologous hematopoietic stem cell support. Improving the quality of grafts with the selection of CD34 positive cells is another approach aimed at reducing plasma cell contamination without impairing haematological recovery. An EBMT randomized study assessing the role of CD34 selection has been initiated by our group Increasingly efficient first-line therapy, better quality autografts and improved post-remission treatment with, for example, anti-idiopathic vaccination are the most promising future directions.     

The biology and clinical relevance of somatostatin receptor scintigraphy in adrenal tumor management

Somatostatin receptors are present in the normal adrenal cortex and medulla. These receptors are also expressed by tumors that cause Cushing's syndrome and by pheochromocytomas. Somatostatin analogues such as octreotide have been developed to target somatostatin receptors for diagnostic and therapeutic purposes. This article reviews the current knowledge of the biology of somatostatin receptors in the normal adrenal gland and in adrenal tumors and defines the current role of the somatostatin receptor in the diagnosis, staging and management of Cushing's syndrome and pheochromocytomas.     

Signal transduction pathways and their relevance in human astrocytomas

Aberrations in a number of signal transduction pathways have been identified as playing a key role in the molecular pathogenesis of astrocytomas and their progression to high grade glioblastoma multiforme (GBM). GBMs are characterized by overexpression of the Platelet Derived Growth Factor Receptors (PDGFR) and their ligands (PDGF), as well as the Epidermal Growth Factor Receptor (EGF-R). These receptors activate the Ras pathway, a key cellular signal transduction pathway, culminating in the activation of a wide range of Ras-dependent cellular events. GBMs have also been found to either overexpression or lose expression of various Protein Kinase C (PKC) isoforms. Major strides are being made in developing pharmacological agents which specifically inhibit these growth factor receptors and intracellular signal transduction pathways. Elucidating the role of these pathways in GBMs is thus of major clinical importance, as these novel molecularly-targeted agents may prove of use in the clinical management of GBMs in the future.     

Comparison among strains of porcine reproductive and respiratory syndrome virus for their ability to cause reproductive failure

OBJECTIVE: To compare the virulence of selected strains of porcine reproductive and respiratory syndrome virus (PRRSV) relative to reproductive performance of pregnant gilts. DESIGN: 16 pregnant gilts (principals) were exposed oronasally to 4 strains (vaccine strain RespPRRS, field strains VR-2385, VR-2431, and NADC-8, 4 gilts/strain) of PRRSV on or about day 90 of gestation, 4 pregnant gilts (controls) were kept under similar conditions, except for exposure to PRRSV. Samples and specimens obtained from gilts, pigs (before ingestion of colostrum), and fetuses were tested for PRRSV and homologous antibody. ANIMALS: 20 pregnant gilts. PROCEDURE: The virulence of each strain of PRRSV was evaluated mainly on the clinical status of the corresponding litters at farrowing. RESULTS: Most gilts remained clinically normal throughout the study and farrowed normally at or near the expected farrowing time. All virus strains crossed the placenta of principal gilts to infect fetuses in utero. The number of late-term dead fetuses (which appeared to be the best measure of relative virulence) ranged from 0 for litters of control gilts and gilts exposed to strain RespPRRS, to 38 for gilts exposed to strain NADC-8. All principal gilts became viremic and developed antibody against PRRSV. All strains persisted in alveolar macrophages of at least some principal gilts for at least 7 weeks after exposure. CONCLUSION: Strains of PRRSV vary in virulence. CLINICAL RELEVANCE: The effects of PRRSV on reproductive performance are strain dependent and this should be considered in making a tentative diagnosis on the basis of clinical observations.     

A discussion of hospital social atmosphere profiles and their relevance to effectiveness.

Recent data purporting to show that hospital social atmospheres lead to hospital effectiveness were questioned on the basis of sampling, design, and strong indications that an alternative explanation was as reasonable as the one put forward by the authors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The relevance of data on physicians and disability on the right to assisted suicide: Can empirical studies resolve the issue?

Opponents of a right to physician-assisted suicide rely heavily on the results of several empirical studies, particularly data concerning physicians and other health professionals. This commentary on C. J. Gill's article examining the suitability of people with irreversible disabilities to be candidated for assisted suicide (see record 2001-17060-021) concludes that values, not empirical data, must ultimately determine the legality of assisted suicide. Studies cannot resolve the fundamental issue. (PsycINFO Database Record (c) 2010 APA, all rights reserved)