University of Texas System

About: University of Texas System is a education organization based out in Austin, Texas, United States. It is known for research contribution in the topics: Cancer & Population. The organization has 13901 authors who have published 10925 publications receiving 319328 citations. The organization is also known as: UT System.

Release of dopamine from tuberoinfundibular neurons into pituitary stalk blood after prolactin or haloperidol administration

Abstract: The effects of PRL or haloperidol on the release of dopamine from tuberoinfundibular neurons were assessed by measuring the concentrations of dopamine in hypophysial portal plasma. The mean concentration of dopamine in portal plasma of male rats which had received an intracerebroventricular injection of PRL or a sc injection of haloperidol on the day before the collection of pituitary stalk blood was approximately 5 times that in stalk plasma of vehicle-treated control rats. The haloperidol- induced increase in the concentration of dopamine in pituitary stalk plasma appeared to be PRL mediated, since this effect of haloperidol was significantly attenuated in rats which had been pretreated with antiserum to PRL. These observations are consistent with the view that the mechanisms involved in the release of dopamine from tuberoinfundibular neurons are regulated, in part, by PRL. Moreover, in view of the inhibitory effect of dopamine on PRL secretion, a PRL-induced increase in the release of dopamine from tub...

Process for production of nanoparticles and microparticles by spray freezing into liquid

Abstract: The present invention provides a system and a method for the production of microparticles and nanoparticles of materials that can be dissolved. The system and method of the present invention provide quicker freezing times, which in turn produces a more uniform distribution of particle sizes, smaller particles, particles with increased porosity and a more intimate mixing of the particle components. The system and method of the present invention also produce particles with greater surface area than conventional methods. One form of the present invention provides a method for the preparation of particles. An effective ingredient is mixed with water, one or more solvents, or a combination thereof, and the resulting mixture is sprayed through an insulating nozzle located at or below the level of a cryogenic liquid. The spray generates frozen particles.

Age-Related Changes in the Leydig Cell Population, Seminiferous Tubules, and Sperm Production in Stallions

Abstract: Age-related changes in the Leydig cell population of horses between 2 and 20 years old were characterized by a twofold increase in Leydig cell number per gram parenchyma, a threefold increase in Leydig cell number per testis, a threefold increase in Leydig cell volume per gram parenchyma, and a fivefold increase in Leydig cell volume per testis. Due to the increased volume of Leydig cells per gram of testicular parenchyma and the increased size and accumulation of lipofuscin granules in individual cells, the gross appearance of the parenchyma became darker with age. The Leydig cell population increased with age by replacing the noncellular components of the interstitium and did not alter the proportion of the testis occupied by blood vessels, lymph vessels, or seminiferous tubules. Both the diameter and length of seminiferous tubules increased with age. Daily sperm production per testis increased between postpuberty and adulthood yet did not increase significantly beyond adulthood. However, the number of Leydig cells per testis continued to increase in the aging horse. Other significant changes included increases in testicular weight, volume of Leydig cells per testis, seminiferous tubular length per testis, and daily sperm production per testis in April-May compared with February-March.

Identification and characterization of zebrafish thrombocytes

Abstract: To analyse primary haemostasis in the zebrafish we have identified and characterized the zebrafish thrombocyte by morphologic, immunologic and functional approaches. Novel methods were developed for harvesting zebrafish blood with preservation of thrombocytes, and assaying whole blood adhesion/aggregation responses in microtitre plates. Light and electron microscopy of the thrombocyte illustrated morphological characteristics including the formation of aggregates, pseudopodia, and surface-connected vesicles analagous to the platelet canalicular system. Immunostaining with polyclonal antisera versus human platelet glycoproteins demonstrated the presence of glycoprotein Ib and IIb/IIIa-like complexes on the thrombocyte surface. Whole blood assays for adhesion/aggregation and ATP release showed ristocetin-induced adhesion without ATP release, and platelet agonist (collagen, arachidonic acid) induced aggregation with ATP release. Blood harvested from zebrafish treated with aspirin demonstrated inhibition of arachidonic acid induced aggregation and agonist induced ATP release, consistent with at least partial dependence on an intact cyclo oxygenase pathway. The combined morphologic immunologic and functional evidence suggest that the zebrafish thrombocyte is the haemostatic homologue of the mammalian platelet. Conservation of major haemostatic pathways involved in platelet function and coagulation suggests that the zebrafish is a relevant model for mammalian haemostasis and thrombosis.