University of Texas Health Science Center at Houston

About: University of Texas Health Science Center at Houston is a education organization based out in Houston, Texas, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 27309 authors who have published 42520 publications receiving 2151596 citations. The organization is also known as: UTHealth & The UT Health Science Center at Houston.

A Comparison of Demineralized Freeze‐Dried Bone and Autologous Bone to Induce Bone Formation in Human Extraction Sockets

Abstract: The purpose of this study was to test the bone-forming capacity of demineralized freeze-dried bone (DFDBA) and autologous bone grafts in extraction sockets. Seven paired sites were grafted with either DFDBA or autologous bone. The sites were reentered between 3 and 13 months for the purposes of obtaining biopsies of the grafted sites and to place endosseous implants. Biopsies from 6 of the 7 grafted sites were evaluated for new bone formation. DFDBA sites revealed the presence of dead particles of DFDBA with no evidence of bone formation on the surfaces of the implanted particles and no evidence of osteoclastic resorption of the bone particles. Biopsies from the 6 autologous sites revealed vascular channels with woven and lamellar bone. Some specimens had retained cortical, non-vital bone chips. These bone chips were undergoing active osteoclastic resorption. The results of this study questions the use of DFDBA as a bone inductive graft material. J Periodontol 1994;65:1128–1133.

Attitudes, Norms, and Self-Efficacy: A Model of Adolescents' HIV-Related Sexual Risk Behavior:

Abstract: Using data from a cross-sectional, statewide survey of 1,720 Texas ninth graders in 13 school districts, a model of psychosocial predictors of human immunodeficiency virus (HIV)-related sexual risk behavior was tested. Predictor variables in the model, based on variables from the Theory of Reasoned Action and Social Learning Theory, were attitudes, norms, self-efficacy, and behavioral intentions. Attitudes, norms, and self-efficacy predicted 36.4% of the variance in the intention to limit the number of sexual partners and the same variables plus intention predicted 24.6% of the variance in number of sexual partners in the past year. Attitudes, norms, and self-efficacy regarding condom use predicted 17.0% of the variance in condom use intentions; these variables plus intentions predicted 19.0% of the variance in condom use frequency. Attitudes, norms, and intentions were directly related to the number of sexual partners, while self-efficacy ad condom use intentions were directly related to frequency of condom use.

Fludarabine potentiates metabolism of cytarabine in patients with acute myelogenous leukemia during therapy.

Abstract: Purpose A protocol was designed to test the hypothesis that fludarabine infusion before arabinosylcytosine (cytarabine [ara-C]) would increase the accumulation of the active metabolite ara-C triphosphate (ara-CTP) in acute myelogenous leukemia (AML) blasts during therapy. Patients and methods Patients (n = 5) received 1 g/m2 of ara-C infused intravenously (IV) for 2 hours, followed at 20 hours by 30 mg/m2 of fludarabine for 30 minutes. At 24 hours, another identical dose of ara-C was infused. To determine the optimal duration of ara-C infusion following fludarabine, five additional patients were treated on an amended protocol in which the ara-C infusion was extended to 3 g/m2 infused over 6 hours. Results Comparison of ara-CTP pharmacokinetics in circulating AML cells demonstrated that the area under the curve (AUC) of ara-CTP increased significantly (median, 1.8-fold; range, 1.6 to 2.4; P = .004) after fludarabine infusion. Neither the median plasma ara-C concentrations, the levels of its deamination product arabinosyluracil, nor the rate of ara-CTP elimination from circulating blasts was affected by fludarabine infusion. However, the rate of ara-CTP accumulation by AML cells was increased by a median of 2.0-fold (range, 1.8 to 2.2; P = .001) after fludarabine; the peak occurred within 1 hour of the end of the infusion. In vitro incubation of these cells with arabinosyl-2-fluoroadenine (F-ara-A) before ara-C also produced a median 1.7-fold increase in the ara-CTP accumulation rate. Pharmacology studies in patients receiving 6-hour infusions of ara-C demonstrated that the rate of ara-CTP accumulation was potentiated beyond 2 hours, but not for 6 hours. Conclusion Infusion of fludarabine before ara-C augments the rate of ara-CTP synthesis in circulating AML blasts during therapy. Evaluation of 6-hour ara-C infusions demonstrated that potentiation of ara-CTP synthesis is maximal up to 4 hours in most patients; this pharmacologically optimized regimen should be considered for combination with other antileukemia drugs.

Pattern of polymorphism after strong artificial selection in a domestication event

Abstract: The process of strong artificial selection during a domestication event is modeled, and its effect on the pattern of DNA polymorphism is investigated. The model also considers population bottleneck during domestication. Artificial selection during domestication is different from a regular selective sweep because artificial selection acts on alleles that may have been neutral variants before domestication. Therefore, the fixation of such a beneficial allele does not always wipe out DNA variation in the surrounding region. The amount by which variation is reduced largely depends on the initial frequency of the beneficial allele, p. As a consequence, p has a strong effect on the likelihood of detecting the signature of selection during domestication from patterns of polymorphism. These theoretical results are discussed in light of data collected from maize. Although the main focus of this article is on domestication, this model can also be generalized to describe selective sweeps from standing genetic variation.