University of Texas Health Science Center at San Antonio

About: University of Texas Health Science Center at San Antonio is a education organization based out in San Antonio, Texas, United States. It is known for research contribution in the topics: Population & Melatonin. The organization has 28008 authors who have published 44104 publications receiving 2281613 citations. The organization is also known as: UT Health San Antonio.

Physicochemical and Functional Identity of Rabbit Platelet-Activating Factor (PAF) Released in Vivo during IgE Anaphylaxis with PAF Released in Vitro from IgE Sensitized Basophils

Abstract: Platelet activating factor (PAF) released in vivo into the plasmas of rabbits during development of IgE-induced systemic anaphylactic shock had indistinguishable physicochemical and functional properties when compared with PAF released in vitro from antigen-stimulated, washed buffy coat cells containing IgE-sensitized basophils. Our findings represent the first documentation for the release of PAF in vivo and strongly support its role as an important chemical mediator involved in acute inflammatory reactions and tissue injury. The intravascular release of PAF during IgE anaphylaxis correlated temporally with the development of intravascular platelet aggregation and the development of thrombocytopenia and neutropenia. Passive transfer experiments indicated that IgE-sensitized basophils alone can initiate the intravascular release of PAF and development of the various platelet and neutrophil alterations similar to those observed during the anaphylactic syndrome in the actively immunized rabbit. The PAF released in vivo or in vitro was completely recoverable by chloroform-methanol-water extraction and was easily and completely phased into a chloroformrich layer after the addition of water. All of the PAF samples studied consistently migrated on thin layer chromatography as a sharp band between sphingomyelin and lysolecithin on silica gel G plates by utilizing a solvent system of chloroform-methanol-water, 65:35:4, v/v. The mobility of the PAF on thin layer chromatography was essentially unaffected when chloroformmethanol-acetic acid-water, 25:15:4:2, v/v, or chloroform-methanol-25% ammonia 65:35:4, v/v, were utilized as the solvent systems. These observations, coupled with the fact that PAF preparations could not be extracted from the chloroform solution with NaHCO 3 argue for a neutral lipid molecule. Functional PAF activity and migratory properties on thin layer chromatography were stable to acid conditions, exposure to air, treatment with periodic acid or sodium nitrite, but were exquisitely labile to methanolic NaOH. The above characteristics would eliminate the occurrence of a structure containing a vinyl ether linkage, a free glycerol, glycol or sugar moiety, but would support a neutral polar lipid containing a fatty acid ester group.

Mechanical strain opens connexin 43 hemichannels in osteocytes: a novel mechanism for the release of prostaglandin.

Abstract: Mechanosensing bone osteocytes express large amounts of connexin (Cx)43, the component of gap junctions; yet, gap junctions are only active at the small tips of their dendritic processes, suggestin...

Platelet-activating factor: receptors and signal transduction

Abstract: During the past two decades, studies describing the chemistry and biology of PAF have been extensive. This potent phosphoacylglycerol exhibits a wide variety of physiological and pathophysiological effects in various cells and tissues. PAF acts, through specific receptors and a variety of signal transduction systems, to elicit diverse biochemical responses. Several important future directions can be enumerated for the characterization of PAF receptors and their attendant signalling mechanisms. The recent cloning and sequence analysis of the gene for the PAF receptor will allow a number of important experimental approaches for characterizing the structure and analysing the function of the various domains of the receptor. Using molecular genetic and immunological technologies, questions relating to whether there is receptor heterogeneity, the precise mechanism(s) for the regulation of the PAF receptor, and the molecular details of the signalling mechanisms in which the PAF receptor is involved can be explored. Another area of major significance is the examination of the relationship between the signalling response(s) evoked by PAF binding to its receptor and signalling mechanisms activated by a myriad of other mediators, cytokines and growth factors. A very exciting recent development in which PAF receptors undoubtedly play a role is in the regulation of the function of various cellular adhesion molecules. Finally, there remain many incompletely characterized physiological and pathophysiological situations in which PAF and its receptor play a crucial signalling role. Our laboratory has been active in the elucidation of several tissue responses in which PAF exhibits major autocoid signalling responses, e.g. hepatic injury and inflammation, acute and chronic pancreatitis, and cerebral stimulation and/or trauma. As new experimental strategies are developed for characterizing the fine structure of the molecular mechanisms involved in tissue injury and inflammation, the essential role of PAF as a primary signalling molecule will be affirmed. Doubtless the next 20 years of experimental activity will be even more interesting and productive than the past two decades.

Prospective Multicenter Surveillance Study of Funguria in Hospitalized Patients

Abstract: Although fungal urinary tract infections are an increasing nosocomial problem, the significance of funguria is still not clear. This multicenter prospective surveillance study of 861 patients was undertaken to define the epidemiology, management, and outcomes of funguria. Diabetes mellitus was present in 39% of patients, urinary tract abnormalities in 37.7%, and malignancy in 22.2%; only 10.9% had no underlying illnesses. Concomitant nonfungal infections were present in 85%, 90% had received antimicrobial agents, and 83.2% had urinary tract drainage devices. Candida albicans was found in 51.8% of patients and Candida glabrata in 15.6%. Microbiological and clinical outcomes were documented for 530 (61.6%) of the 861 patients. No specific therapy for funguria was given to 155 patients, and the yeast cleared from the urine of 117 (75.5%) of them. Of the 116 patients who had a catheter removed as the only treatment, the funguria cleared in 41 (35.3%). Antifungal therapy was given to 259 patients, eradicating funguria in 130 (50.2%). The rate of eradication with fluconazole was 45.5%, and with amphotericin B bladder irrigation it was 54.4%. Only 7 patients (1.3%) had documented candidemia. The mortality rate was 19.8%, reflecting the multiple serious underlying illnesses found in these patients with funguria.