Measuring the reinforcing strength of abused drugs

Animal models for human diseases are highly valued for their utility in developing new therapies. Animals have long provided suitable platforms for the development of innovative surgical procedures and for the study of disease states that are relatively easy to produce in otherwise healthy animals, such as diabetes or hypertension. Increasingly, new strains of animals susceptible to common human illnesses are being introduced into medical research, promising new inroads into the treatment of a variety of organic disorders. Despite these advances in model development, psychiatric disorders, by and large, remain among the hardest to induce experimentally, and the search for reasonable animal procedures to study diseases of the mind is an ongoing challenge for experimental biologists. An exception to this limitation, however, comes in the study of drug abuse. Major developments in this area of research over the last several decades have steadily advanced our ability to identify pharmacological, genetic, and environmental determinants that contribute to the development of drug dependence and addictive behavior.     

Relations between hydrological variables and year-class strength of sportfish in eight Florida waterbodies

Hydrological variables have influenced fish recruitment in lakes, reservoirs and rivers. We evaluated how annual and seasonal hydrological variables were related to year-class strength (i.e., residuals from catch curves) of sportfish across eight Florida waterbodies (four rivers and four lakes). Multiple regression equations computed for black bass Micropterus spp. were combined across rivers and year-class strength was negatively related to spring median flow rates and in some cases positively related to winter median flow rates (all p0.10). Conversely, Lepomis spp. residuals combined from the rivers indicated that year-class strength was positively related to median flow rates in the fall prior to spawning and negatively related to post-spawn fall median flow rates (all p0.10). Fish recruitment combined across lakes were not related to water levels in this study, although within lake relationships did occur in some instances. Ecological implications of this work include regulations such as minimum flows and levels (MFLs) regarding sportfish species. Impacts of hydrology on year-class strength of sportfish were stronger in rivers than in lakes for these Florida systems. High flows at least once every 3years in the fall may allow inundation of floodplain habitat, providing favorable environmental conditions for Lepomis spp. reproduction. Setting MFLs during periods of drought (i.e., 3years or more) should consider impacts to short-lived species such as Lepomis spp.     

Relations between animal transgenesis and reproduction

Transgenesis has become an essential tool for the study of gene expression mechanisms and functions. Transgenesis is also more and more used for biotechnological applications such as the study of human diseases, the adaptation of pig organs to humans, the production of pharmaceutical proteins in milk and likely in the future for the improvement of animal production. The use of transgenesis relies on the efficiency of gene transfer. New tools have been recently designed to improve gene transfer. The methods of gene transfer are highly dependent on the techniques of animal reproduction. Conversely, the need to improve transgenesis urges researchers to study some of the key steps in reproduction and to find new techniques for gene transfer. This paper summarises the recent data and the perspectives offered by animal transgenesis.     

Relations and dependencies between morphological characters

In biological classification, a character is a property of a taxon that can distinguish it from other taxa. Characters are not independent, and the relations between characters can arise from structural constraints, developmental pathways or functional constraints. That has lead to famous controversies in the history of biology. In addition, a character as a tool of data analysis has some subjective aspects. In this contribution, I develop algebraic and geometric schemes to address these issues in a mathematical framework.     

Relations of self-regulation and self-efficacy for exercise and eating and BMI change: A field investigation

Objectives  

This study aimed to assess relations of self-regulatory skill use with self-efficacy for exercise and appropriate eating, and the resulting change in weight associated with participation in a nutrition and exercise treatment supported by cognitive-behavioral methods.     

Relations between biochemical thermodynamics and biochemical kinetics

The parameters in steady-state or rapid-equilibrium rate equations for enzyme-catalyzed reactions depend on the temperature, pH, and ionic strength, and may depend on the concentrations of specific species in the buffer. When the complete rate equation (i.e. the equation with parameters for the reverse reaction as well as the forward reaction) is determined, there are one or more Haldane relations between some of the kinetic parameters and the apparent equilibrium constant for the reaction that is catalyzed. When the apparent equilibrium constant can be calculated from the kinetic parameters, the equilibrium composition can be calculated. This is remarkable because the kinetic parameters all depend on the properties of the enzymatic site, but the apparent equilibrium constant and the equilibrium composition do not. The effects of ionic strength and pH on the unoccupied enzymatic site and the occupied enzymatic site have to cancel in the Haldane relation or in the calculation of the apparent equilibrium constant using the rate constants for the steps in the mechanism. Several simple enzymatic mechanisms and their complete rate equations are discussed.     

Relations between blood polymorphism and uterine carcinoma

In a study of 63 female patients with cervical carcinoma and 37 with corpus carcinoma (all patients from Hamburg), polymorphisms of the blood were determined, which have not previously or only rarely been studied in such patients. Comparisons with a control group revealed no significant differences for the MNSs, P, Jk, SEP, PGM, GPT, EsD, Hp, Gc, and Gm systems. The patients with corpus carcinoma, however, exhibited a lesser frequency of Ccee and an increased frequency of homozygotes in the Fy system. Furthermore, the proportion of patients with GLO1 was greater among the women with cervix carcinoma.