Differetial sensitivity of spontaneously hypertensive rats to the hypothermic effect of dopaminergic drugs

The dopaminergic agonist apomorphine produces dose-related hypothermia in naive rats as does L-DOPA in carbidopa-pretreated rats. The hypothermic responses to these two dopaminergic drugs were significantly more pronounced and prolonged in the spontaneously hypertensive rat than in normotensive Wistar control rats. The greater sensitivity of the SHR to these drugs was reflected as a leftward shift of the dose-response curves for apomorphine- and L-DOPA-induced hypothermias.     

Hydrocarbon-metabolizing activity of various mammalian cells in culture

Summary Two methods for determining the hydrocarbon-metabolizing enzyme activity of cultured mammalian cells were compared. The method designed to measure benzo[a]an-thracene-induced aryl hydrocarbon hydroxylase activity could detect and quantify enzyme activities in low passage rodent cells, but could not reproducibly detect levels in intermediate or high passage mouse, rat, or human cells. The method designed to measure the ability of a cell to convert benzo[a]pyrene from an organic-soluble to an aqueous acetone-soluble form proved to be more reproducible. This technique, when modified, was demonstrated to be an effective screening test for the detection of those lines with higher levels of hydrocarbon-metabolizing enzymes. Supported by the Council for Tobacco Research and Contract NIH 70-2068 within the Virus Cancer Program, National Cancer Institute, National Institutes of Health.     

Limb regeneration of the adult newt (Notophthalmus viridescens) in the absence of the spleen

Summary It has been suggested that the immune system might figure prominently in the regulation of forelimb regeneration. However, neither the nature of this influence nor the aspect(s) of regeneration influenced are clearly known. The determination of which components of the immune system are indispensable for regeneration would be a logical first step in attempting to address such questions. This investigation, therefore, examined the effects of removing the spleen, a major lymphoid organ in the newt, upon the progress of regeneration. Splenectomies performed concomitantly with or after forelimb amputation failed to alter the time course of regeneration. Splenectomies, but not sham-splenectomies, performed prior to amputation reduced the time required to achieve successive stages of regeneration under some, but not all conditions, i.e., when performed 10–20 days before amputation, during the late fall and winter. Up until 35 days after amputation, no gross morphological distortions were observed as a result of splenectomy. It was concluded that the spleen is not required for regeneration to occur.Portions of this work constitute part of the thesis submitted by M.E. Fini in partial fulfillment of the requirements for the M.S. degree in Biology at Boston College     

1-Alkyl-3-amino-5-aryl-1H-[1,2,4]triazoles: novel synthesis via cyclization of N-acyl-S-methylisothioureas with alkylhydrazines and their potent corticotropin-releasing factor-1 (CRF(1)) receptor antagonist activities.

Cyclizations of alkylhydrazines with N-acyl-S-methylisothioureas, readily synthesized from acyl chlorides, sodium thioisocyanate, dialkylamines then methyl iodide in a one-pot reaction, gave 1-alkyl-3-dialkylamino-5-phenyltriazoles 7 as major products. The regioisomers were assigned through the use of NOE NMR experiments. While bearing a N-bis(cyclopropyl)methyl-N-propylamino group, this series of compounds shows very good binding affinity on the human CRF₁ receptor. Among them, 1-methyl-3-[N-bis(cyclopropyl)methyl-N-propylamino]-5-(2,4-dichlorophenyl)-1H-[1,2,4]triazole 7a had the best binding affinity for the CRF₁ receptor (K_i=9 nM).     

Cardiac Fibroblasts Contribute to Myocardial Dysfunction in Mice with Sepsis: The Role of NLRP3 Inflammasome Activation

Myocardial contractile dysfunction in sepsis is associated with the increased morbidity and mortality. Although the underlying mechanisms of the cardiac depression have not been fully elucidated, an exaggerated inflammatory response is believed to be responsible. Nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) inflammasome is an intracellular platform that is involved in the maturation and release of interleukin (IL)-1β. The aim of the present study is to evaluate whether sepsis activates NLRP3 inflammasome/caspase-1/IL-1β pathway in cardiac fibroblasts (CFs) and whether this cytokine can subsequently impact the function of cardiomyocytes (cardiac fibroblast-myocyte cross-talk). We show that treatment of CFs with lipopolysaccharide (LPS) induces upregulation of NLRP3, activation of caspase-1, as well as the maturation (activation) and release of IL-1β. In addition, the genetic (small interfering ribonucleic acid [siRNA]) and pharmacological (glyburide) inhibition of the NLRP3 inflammasome in CFs can block this signaling pathway. Furthermore, the inhibition of the NLRP3 inflammasome in cardiac fibroblasts ameliorated the ability of LPS-chalenged CFs to impact cardiomyocyte function as assessed by intracellular cyclic adenosine monophosphate (cAMP) responses in cardiomyocytes. Salient features of this the NLP3 inflammasome/ caspase-1 pathway were confirmed in in vivo models of endotoxemia/sepsis. We found that inhibition of the NLRP3 inflammasome attenuated myocardial dysfunction in mice with LPS and increased the survival rate in mice with feces-induced peritonitis. Our results indicate that the activation of the NLRP3 inflammasome in cardiac fibroblasts is pivotal in the induction of myocardial dysfunction in sepsis.     

Alteration of membrane permeability by amphotericin B

Amphotericin B (AmB) increased unidirectional Na transport and net transcellular sodium movements across the skin of the frog, Rana pipiens, when added to the solution bathing the corium side, but not from the outer epidermal surface. The AmB response was prevented with pretreatment with amiloride, ouabain and mucosal sodium substitution. Alteration in pH markedly reduced the permeability changes induced by AmB. AmB did not interfere with the increase in sodium transport induced by antidiuretic hormone. The present study demonstrates that AmB interacts with the skin of the frog, Rana pipiens, from the corium side specifically increasing transepithelial sodium transport. The increase in transport apparently occurs through the existing sodium pathway.