Androgen maintenance of erectile function in the rat penis.

Previous research has shown that the frequency and duration of penile erection is diminished after castration and that replacement with testosterone will restore the process. Using rats, the present study was designed to confirm that erection is androgen-dependent and to determine whether castration and androgen replacement affect the penile vascular smooth muscle responsiveness to vasoactive drugs. Blood pressure in the corpus cavernosum was measured directly during erections induced by electrical stimulation of the autonomic innervation of the penis. Maximal cavernosal pressure was markedly reduced after castration but was returned to normal levels if the castrated animals were treated with testosterone. Infusion of nitroglycerin (vasodilator) or phenylephrine (vasoconstrictor) resulted in a decline in cavernosal pressure in androgen-treated animals but not in castrated animals, even though the mean arterial blood pressure was strongly affected in all treatment groups by these drugs. When an inhibitor of nitric oxide synthesis was infused, cavernosal pressure was decreased in all groups, indicating that this substance is involved in penile erection. Taken together, these results show that androgens maintain the erectile process and may act specifically to support the responsiveness of the vascular smooth muscle to vasoactive drugs.     

Phytochemical complementarities among endophyte-infected tall fescue, reed canarygrass, birdsfoot trefoil and alfalfa affect cattle foraging

We determined whether plant diversity and sequence of plant ingestion affected foraging when cattle chose from plants that varied in concentrations of alkaloids, tannins and saponins. We hypothesized cattle that ate high-alkaloid grasses (endophyte-infected tall fescue (TF) or reed canarygrass (RCG)) would prefer forages high in tannins (birdsfoot trefoil, BFT+) or saponins (alfalfa, ALF+), because tannins and saponins can bind to alkaloids, presumably reducing their absorption. We further hypothesized that forages with tannins or saponins consumed before, rather than after, foraging on high-alkaloid grasses would promote greater use of those grasses presumably by binding to alkaloids, thereby reducing their absorption. In Phase 1, cattle (n = 32) grazed on either high (+) or low (-) alkaloid grass (TF or RCG) pastures for 30 min each morning at 0600 h and were then offered a choice of BFT+, BFT-, ALF+ and ALF- for 60 min each day for 12 days. In Phase 2, cattle (n = 32) were first offered a choice of BFT+ or ALF+ for 30 min at 0600 h and then placed on grass (TF+ or -, or RCG+ or -) pastures for 60 min for 12 days. In both phases, we had four spatial replications of four treatments with 2 per calves assigned to each of the 16 replications per treatment combinations. Scan samples of individuals at 2-min intervals were used to determine incidence of foraging on each plant species (%). Cattle grazed more on RCG than on TF in Phases 1 (62% v. 27%; P = 0.0015) and 2 (71% v. 32%; P = 0.0005). In Phase 1, cattle that first foraged on RCG+ or TF- subsequently preferred ALF over BFT, whereas cattle offered RCG- or TF+ foraged on ALF and BFT equally. Foraging by cattle on RCG was cyclic during Phase 1, whereas cattle foraging on TF markedly decreased incidence of use of TF from 41% to only 16% by the end of the 12-day trial (P = 0.0029). Contrary to the cyclic (RCG) or steadily declining (TF) use of grasses in Phase 1, cattle steadily and dramatically increased foraging on both RCG and TF throughout Phase 2, when they first grazed BFT+ or ALF+ followed by high-alkaloid grasses (P = 0.0159). Our findings suggest that in plant species the sequence of ingestion influenced foraging behavior of cattle and that secondary compounds influenced those responses.     

An integrative expression vector for <Emphasis Type="Italic">Actinosynnema pretiosum</Emphasis>

Background  

The Actinomycete Actinosynnema pretiosum ssp. auranticum has commercial importance due to its production of ansamitocin P-3 (AP-3), a potent antitumor agent. One way to increase AP-3 production would be to constitutively express selected genes so as to relieve bottlenecks in the biosynthetic pathway; however, an integrative expression vector for A. pretiosum is lacking. The aim of this study was to construct a vector for heterologous gene expression in A. pretiosum.     

Development and standardization of multiplexed antibody microarrays for use in quantitative proteomics

BACKGROUND: Quantitative proteomics is an emerging field that encompasses multiplexed measurement of many known proteins in groups of experimental samples in order to identify differences between groups. Antibody arrays are a novel technology that is increasingly being used for quantitative proteomics studies due to highly multiplexed content, scalability, matrix flexibility and economy of sample consumption. Key applications of antibody arrays in quantitative proteomics studies are identification of novel diagnostic assays, biomarker discovery in trials of new drugs, and validation of qualitative proteomics discoveries. These applications require performance benchmarking, standardization and specification. RESULTS: Six dual-antibody, sandwich immunoassay arrays that measure 170 serum or plasma proteins were developed and experimental procedures refined in more than thirty quantitative proteomics studies. This report provides detailed information and specification for manufacture, qualification, assay automation, performance, assay validation and data processing for antibody arrays in large scale quantitative proteomics studies. CONCLUSION: The present report describes development of first generation standards for antibody arrays in quantitative proteomics. Specifically, it describes the requirements of a comprehensive validation program to identify and minimize antibody cross reaction under highly multiplexed conditions; provides the rationale for the application of standardized statistical approaches to manage the data output of highly replicated assays; defines design requirements for controls to normalize sample replicate measurements; emphasizes the importance of stringent quality control testing of reagents and antibody microarrays; recommends the use of real-time monitors to evaluate sensitivity, dynamic range and platform precision; and presents survey procedures to reveal the significance of biomarker findings.     

Effect of ionizing radiation on thymic epithelial cell function. I. Radiation-spared thymic epithelial grafts expedite the recovery of T cell function in lethally irradiated and fetal liver reconstituted mice

A murine model system was developed to determine whether ionizing radiation has a detrimental influence on thymic epithelium, cell function. Normal mice were lethally irradiated, grafted intracamerally with normal fetal thymic epithelium, and then reconstituted with fetal liver cells. These animals were compared with a group of animals who received their thymic grafts before the irradiation protocol. Analysis of the reconstitution of T cell function in peripheral lymph nodes and spleens at various times post transplantation demonstrated that animals with radiation-spared thymic grafts had superior proliferative responses to T cell mitogens and alloantigens. It was also determined that the capacity of these animals to elicit contact hypersensitivity responses was significantly greater when compared with animals whose thymic grafts had been radiated. The observed difference in T cell function could not be ascribed to a difference in the rate of export of mature T cells from the thymic grafts since the absolute number of Thy-1+, L3T4+, or Lyt-2+ lymphocytes present in the peripheral lymphoid compartment of our two groups of animals was equivalent. Immunohistologic analysis of the thymic grafts demonstrated a marked reduction in the medullary compartment of the repopulated grafts that had been exposed to ionizing radiation. The results of this study suggest: 1) that irradiation of the thymic microenvironment during marrow ablative preparative regimens may be in part responsible for some of the immune alterations observed in marrow transplant recipients, and 2) that our model system may provide a valuable tool for delineating the roles played by medullary and cortical epithelial cells of the thymus on the T cell maturation and education processes.     

Thymic modulation of IL-2 and IL-4 synthesis by peripheral T cells

In this paper we provide several lines of evidence to support the hypothesis that the thymus can exert regulatory influences on the functional capabilities of mature recirculating T cells. Our studies demonstrate that while the IL-2-producing potential of T cells that repopulate the secondary lymphoid organs of lethally irradiated and stem cell-reconstituted mice is significantly reduced compared to that of T cells harvested from normal mice, the amount of IL-4 produced by the T cells of these experimental animals is equivalent to, or greater than, the amount produced by T cells from control animals. In addition, we determined that the amount of biologically active IL-2 and IL-4 secreted by T cells harvested from lethally irradiated animals who reconstitute their hematopoietic and immune systems under the influence of nonirradiated thymic epithelial grafts is essentially identical to the amount produced by T cells harvested from nonirradiated control animals. Collectively, these findings suggest that: (1) the alterations observed in the lymphokine-producing potential of T cells harvested from lethally irradiated and stem cell-reconstituted mice is not due to a direct effect of ionizing radiation on the T lymphocytes themselves, and (2) the exposure of the epithelial cells of the thymus to ionizing radiation during marrow-ablative regimens abrogates or modifies a component of thymic function which can influence the lymphokine-secreting potential of recirculating T cells. Further evidence for thymic involvement in the regulation of lymphokine production by peripheral T cells comes from our finding of a post-thymectomy time-dependent reduction in the capacity of T cells from animals to produce IL-2. Coincident with this reduction, T cells harvested from peripheral lymphoid organs of thymectomized animals demonstrated an augmentation in their IL-4-producing capabilities. The finding that treatment of thymectomized animals with the androgen steroid hormone dehydroepiandrosterone reestablished a normal IL-2-producing potential by their T cells makes it unlikely that the reduced capacity to produce IL-2 was secondary to a loss in fresh thymic emigrants.     

The CD11a partner in Sus scrofa lymphocyte function-associated antigen-1 (LFA-1): mRNA cloning, structure analysis and comparison with mammalian homologues

Background  

Lymphocyte function-associated antigen-1 (LFA-1, CD11a/CD18, alphaLbeta2), the most abundant and widely expressed beta2-integrin, is required for many cellular adhesive interactions during the immune response. Many studies have shown that LFA-1 is centrally involved in the pathogenesis of several diseases caused by Repeats-in-toxin (RTX) -producing bacteria.