Detection and characterization of new genetic mutations in individuals heterozygous for lactate dehydrogenase-B(H) deficiency using DNA conformation polymorphism analysis and silver staining

In northwest European countries maternal age is increasing. This will lead to an increase of the prevalence of Down syndrome conceptuses. Meanwhile, the increased use of prenatal cytogenetic diagnosis (PCD) will lead to a decrease in the prevalence of Down syndrome among livebirths. We were interested to know what the result of these two opposite developments would be in the near future, and we describe here a model to quantify these processes and the resulting livebirth prevalence of Down syndrome. The model is demonstrated for The Netherlands from 1992 to 2001. The predicted livebirth prevalence for The Netherlands in 1992 is 1.36 per 1000. Demographic factors will cause an increase to 1.76 per 1000 in 2001 with present indications for PCD and a utilization ratio of 50%. An increase of the utilization ratio to 90% in 2001 will lead to a prevalence of 1.22 per 1000, a little less than the present prevalence. Alternative screening programs, including maternal serum screening, could lead to a further decrease of the livebirth prevalence. The model described here can be used for evaluation of the consequences of alternative forms of Down syndrome screening.     

Evidence of Commingling in Human Eating Behavior

This investigation tested whether distributions of certain aspects of eating behavior were consistent with the notion of a “mixture model;” that is, two or more distinct Commingled component distributions, consistent with the possibility of major gene action. Undergraduates (n=901) completed self-report trait measures of hunger, disinhibition, and dietary restraint. Variables were residualized for gender and age and transformed to remove skewness. Residualized transformed distributions were tested for departure from unimodality with Hartigan's (14) dip statistic. The distributions of all three aspects of eating behavior were significantly non-unimodal. Next, component multivariate normal distributions were estimated via maximum likelihood. Likelihood ratio tests were employed to compare nested models. A mixture of four distributions with unequal variance-covariance matrices tit significantly better than any more parsimonious model. In sum, these data strongly suggest that the distributions of several measures of eating behavior are composed of four component distributions. This finding is consistent with the possibility of major gene effects for eating behavior.     

Bycatch: from emotion to effective natural resource management

Although bycatch has been an acknowledged component of fishery management for many years, its explosive growth as a major management issue has occurred over the past decade. Emergence of the bycatch issue can be traced to increasing world competition for the ocean's fishery resources and the rapid rise of the conservation and environmental movement in recent years. Bycatch has in the past several years been equated to waste, non-selective fishing methods that threaten non-target species and degradation of ocean ecosystems. Although some important steps have been taken to abate bycatch, frequently the problem is not perceived as a component of fishery management, e.g. establishing bycatch mortality rates and evaluating their consequences upon affected populations. Fishery scientists often estimate levels of bycatch, but the overall consequences of discard mortality resulting from the complex of fisheries operating in a region are frequently unknown and speculative. The sum of fishery-induced mortalities occurring as a result of harvesting often involves a significant number of fish in addition to catch and discard. An ICES study group has characterized fishing mortality as the aggregate of all catch mortalities including discard, illegal fishing and misreporting. It is unlikely that managers will, in the near future, have a full accounting of unobserved fishing mortality. Progress toward identifying and measuring such mortalities is receiving increasing attention.The authors suggest and provide an example of a matrix-type analysis for recording bycatch and other fishing mortalities. The matrix presentation would allow managers to evaluate various fishery-related mortality factors and their importance in developing management strategies.     

Strategies for the identification and purification of ligands for orphan biomolecules

The isolation of related genes with evolutionary conserved motifs by the application ofpolymerase chain reaction-based molecular biology techniques, or from database searchingstrategies, has facilitated the identification of new members of protein families. Many of theseprotein molecules will be involved in protein–protein interactions (e.g. growth factors,receptors, adhesion molecules), since such interactions are intrinsic to virtually every cellularprocess. However, the precise biological function and specific binding partners of these novelproteins are frequently unknown, hence they are known as orphan molecules.Complementary technologies are required for the identification of the specific ligands orreceptors for these and other orphan proteins (e.g., antibodies raised against crude biologicalextracts or whole cells). We describe herein several alternative strategies for the identification,purification and characterisation of orphan peptide and protein molecules, specifically thesynergistic use of micropreparative HPLC and biosensor techniques.     

Emerging mechanisms of the behavioral effects of steroids

Within two models of steroid-modulated behavior, sodium appetite and sexual receptivity, novel mechanisms of steroid action have emerged. These include interactions between different types of steroid receptors, plasticity of synapses, activation of unliganded steroid receptors, and rapid effects of steroids. These mechanisms highlight the diversity of steroid action in the central nervous system.     

Computer determination of perfusion patterns in pulmonary capillary networks

Hanger, Christopher C., Robert G. Presson, Jr., Osamu Okada,Steven J. Janke, John J. Watkins, Wiltz W. Wagner, Jr., and Ronald L. Capen. Computer determination of perfusion patterns in pulmonarycapillary networks. J. Appl. Physiol.82(4): 1283-1289, 1997.Individual pulmonary capillaries are notsteadily perfused. By using in vivo microscopy, it can readily bedemonstrated that perfusion continually switches between capillarysegments and between portions of the network within a single alveolarwall. These changes in capillary perfusion occur even when upstream pressure and flow are constant. Flow switching between capillary segments in the absence of hemodynamic changes in large upstream vessels suggests that capillary perfusion patterns could be random. Tocalculate the probability that perfusion patterns could occur bychance, it is necessary to know the total number of possible perfusionpatterns in a given capillary network. We developed a computer programthat can determine every possible perfusion pattern for any givencapillary network, and from that information we can calculate whetherperfusion of individual segments in the network is random. With theresults of the computer program, we have obtained statistical evidencethat some capillary segments in a network are nonrandomly perfused.