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A single-nucleotide mutation in the gene that encodes DHDDS has been identified by whole exome sequencing as the cause of the non-syndromic recessive retinitis pigmentosa (RP) in a family of Ashkenazi Jewish origin in which three of the four siblings have early onset retinal degeneration. The peripheral retinal degeneration in the affected siblings was evident in the initial examination in 1992 and only one had detectable electroretinogram (ERG) that suggested cone-rod dysfunction. The pigmentary retinal degeneration subsequently progressed rapidly. The identified mutation changes the highly conserved residue Lys42 to Glu, resulting in lower catalytic efficiency. Patterns of plasma transferrin isoelectric focusing gel were normal in all family members, indicating no significant abnormality in protein glycosylation. Dolichols have been shown to influence the fluidity and of the membrane and promote vesicle fusion. Considering that photoreceptor outer segments contain stacks of membrane discs, we believe that the mutation may lead to low dolichol levels in photoreceptor outer segments, resulting in unstable membrane structure that leads to photoreceptor degeneration. [ABSTRACT FROM AUTHOR]

The application of Bayesian analysis to the classification of discretized BeadChip⠪ signal intensities generated in the context of multiplex allele analysis is described in this chapter. This analysis enables reliable allele assignment for polymorphic genes, notably those encoding the human leukocyte antigens and the variants of RhCE and RhD antigens. [ABSTRACT FROM AUTHOR]

Skeletal muscle is one of the most heritable quantitative traits studied to date, with heritability estimates ranging from 30% to 85% for muscle strength measures and 50–80% for lean mass measures. The strong genetic contribution to skeletal muscle traits indicates the possibility of using genetic approaches to individualize treatment approaches for sarcopenia or even aid in prevention strategies through the use of genetic screening prior to functional limitations. While these possibilities provide the rationale and motivation for genetic studies of skeletal muscle traits, few genes have been identified to date that appear to contribute to variation in either skeletal muscle strength or mass phenotypes, let alone sarcopenia itself. The ACE, ACTN3, CNTF, and VDR genes have been associated with skeletal muscle strength in two or more papers each, while the AR, TRHR, and VDR genes have been similarly associated with muscle mass. Only the VDR gene has been significantly associated with sarcopenia itself as an endpoint phenotype but replication of this initial finding has not yet been performed. Large-scale clinical studies relying on advanced genome-wide association techniques are needed to provide further insights into potentially clinically relevant genes that contribute to skeletal muscle traits, with identified genes then explored functionally to determine the likelihood that genetic screening can assist in the prevention and treatment of sarcopenia. [ABSTRACT FROM AUTHOR]

In this paper it is demonstrated how two issues from the area of testing electronic components can be merged and solved by means of a genetic algorithm. The two issues are the ordering of test vectors and scan registers with the goal of reducing switching activity during test application and power consumption as a consequence of the ordering. The principles of developing an optimizing procedure with the aim of achieving a solution satisfying the required value of power consumption during power consumption are described here. A basic description of the methodology together with the functions needed to implement the procedures is provided. Experimental results are also discussed. [ABSTRACT FROM AUTHOR]

In this paper we present insights on the problem of haplotype inference for large genotype datasets. Our observations are drawn from an extensive comparison of three methods for haplotype inference using several datasets taken from HapMap. The methods chosen, PTG, Haplorec, and fastPHASE, are among the best known; they are based on different approaches, and are able to deal with large amounts of data. Our analysis controls the execution time and also the accuracy of results, based on the Error Rate and the Switch Error, as well as sequence conservation patterns. The results show that (1) fastPHASE and Haplorec are both more accurate than PTG, (2) fastPHASE is computationally the most expensive of the three methods, while Haplorec may fail to resolve long sequences, and (3) all approaches do better with more conserved sequences, and tend to fail in distinct sequence sites. [ABSTRACT FROM AUTHOR]

HCV is an RNA virus and while 4.1 million people in the USA are currently positive for antibody to HCV, the incidence of new infections is declining. Perinatal transmission is the most common mode of acquiring HCV infection in children. Screening of infants for antibody to HCV should be postponed until 18 months of age as maternal antibodies may persist until then. Evaluation of children with history of multiple transfusions in the decades before routine screening for HCV has provided useful natural history information. The majority of children infected with HCV will go on to develop chronic infection and liver disease of variable severity. Abstract Hepatitis C virus (HCV) infection is a major cause of morbidity and mortality, although the incidence of new infections appears to be declining. HCV is a RNA virus and genotype 1 is most prevalent in this country. After universal testing of blood donors has been enforced, perinatal transmission of HCV has superseded the parenteral route of transmission in the pediatric population. Over 80% of infected HCV individuals go on to develop chronic hepatitis. Numerous host- and virus--related factors have been implicated in the inability to eliminate the virus. A link between HCV and autoimmunity has been proposed. Natural history information in pediatrics is limited but following the course of high-risk children, i.e., recipients of multiple transfusions, hemodialysis, cancer survivors, and transplant recipients, is helpful, especially when these occurred before universal testing for HCV was practiced. Coinfection with HIV causes higher HCV RNA levels and more rapid progression to fibrosis. Future research should be directed to exploring host and viral factors that prevent viral elimination. [ABSTRACT FROM AUTHOR]

A million million spermatozoa, All of them alive: Out of their cataclysm but one poor Noah Dare hope to survive. And among that billion minus one Might there have chanced to be Shakespeare, another Newton, a new Donne, But the One was Me. Although biopolymers are more sophisticated than their simpler cousins, such as polythene and rubber, this alone does not give them an obvious reason for existing. Nucleic-acid codes for proteins, some of which contribute to the formation of further nucleic acid, but if these products were free to float away through the surrounding water, no advantage would be gained by the original molecule. The essential extra factor was discovered over 300 years ago. In 1663, using one of the earliest microscopes, Robert Hooke observed that cork has a structure reminiscent of a honeycomb, with pores separated by diaphragms so as to produce a collection of little boxes, which he called cells. Their universality was not appreciated until 1824, when Henri Dutrochet concluded that entire animals and plants are aggregates of cells, arranged according to some definite plan. He also suggested that growth is caused by an increase in either cell size or cell number, or both. The idea of the cell was further elevated in 1838, when Matthias Schleiden proposed that it is the basic structural unit in all organisms. [ABSTRACT FROM AUTHOR]

Chapter 4 of the book "Psychiatric Mental Health Nursing: Concepts of Care in Evidence-Based Practice" is presented. It explains the functions of cerebrum which comprises the largest part of the human brain. Neurotransmitters are chemicals which are responsible for sending information across synaptic clefts to adjacent target cells. It emphasizes the need for psychiatric nurses to incorporate knowledge of biological sciences to their practices to ensure quality care to mentally ill patients.

Species have been modified, during a long course of descent, … chiefly through the natural selection of numerous successive, slight, favourable variations; aided in an important manner by the inherited effects of the use and disuse of parts; and in an unimportant manner, that is in relation to adaptive structures, whether past or present, by the direct action of external conditions, and by variations which seem to us in our ignorance to arise spontaneously. It appears that I formerly underrated the frequency and value of these latter forms of variation, as leading to permanent modifications of structure independently of natural selection. But as my conclusions have lately been much misrepresented, and it has been stated that I attribute the modification of species exclusively to natural selection, I may be permitted to remark that in the first edition of this work, and subsequently, I placed in a most conspicuous position – namely, at the close of the Introduction – the following words: ‘I am convinced that natural selection has been the main but not the exclusive means of modification.’ This has been of no avail. Great is the power of steady misrepresentation; but the history of science shows that fortunately this power does not long endure. If there is but one passage in all Darwin's publications that set the stage for the discussion of evolutionary theory in the closing decades of the nineteenth century, it is this paragraph from the conclusion to the last edition of the Origin of Species (1872). [ABSTRACT FROM AUTHOR]

The story of the development of the synthetic theory of evolution, named from Julian Huxley 's contribution, Evolution The Modern Synthesis (1942), has been told many times, notably in Mayr (1982) and in the collective work, Mayr and Provine (1980). As Mayr has frequently emphasised, population thinking - seeing anagenesis as the establishment of new forms in interbreeding populations - plus the biological species concept, traceable to John Ray in the seventeenth century (Ray 1686; see Chapter 14), were necessary before the theory could be developed. Theoretical population genetics - the mathematical modelling of genes in populations – was developed with different emphases by Fisher, Haldane, and Sewall Wright. Contemporary with them, Chetverikov and his colleagues in Russia were not only developing parallel ideas but testing them on wild populations of the fruit-fly Drosophila, Morgan 's choice of experimental animal. Dobzhansky, not a member of Chetverikov 's group but strongly influenced by them, continued his work in the United States in a series of papers on D. pseudoobscura from 1938 to 1976 and also produced what is usually considered the first great book of the synthesis, Genetics and the Origin of Species, in 1937. The others usually recognized are Huxley 's; Mayr 's Systematics and the Origin of Species (1942); Rensch (1947), translated in its second edition as Evolution Above the Species Level (1959); and Simpson 's Tempo and Mode in volution (1944), considerably changed (Gould 1980c) and reissued as The Major Features of Evolution (Simpson 1953). [ABSTRACT FROM AUTHOR]

It is not my intention, in these two chapters on theories of evolutionary mechanism, to give a detailed history. For a more complete account readers should consult Mayr 's Growth of Biological Thought (1982), Bowler 's (1983) account of rival theories to Darwinism from the publication of the Origin in 1859 until the development of the “Neo-Darwinian” synthetic theory and finally the multi-author work on the development of the synthesis itself (Mayr and Pro vine 1980). The pre-Darwinian history of evolutionary theory in nineteenth-century Britain is treated in its sociological context by Desmond (1989). These two chapters have four principal themes: in Chapter 11, (1) a discussion of Lamarck 's theory of mechanism, representing the first complete, if flawed, evolutionary theory; (2) a critique of Darwin's and Wallace 's theory of Natural Selection; (3) the contrasting theories supported “post Darwin” and referred to above; and, in Chapter 12, (4) a critique of the Synthetic Theory and reactions to it, thus bringing the account up to date. In passing, however, we may refer to the theories of Etienne Geoffroy Saint-Hilaire and Robert Chambers, both of whom have been discussed in previous chapters. Geoffroy (1772-1844) speculated about evolution late in life (Mayr 1982). [ABSTRACT FROM AUTHOR]

We have seen in Chapter 6 and the previous chapters that dissatisfaction with traditional taxonomy gave rise, after the Second World War, to two distinct attempts at a remedy – phenetics and cladistics. In this chapter, I review the methodology of these two schools, as they were originally proposed and developed. In each case I describe the principles and methods, which I hope will be sufficiently clear to non-taxonomic readers to enable them to follow the subsequent discussion. In each case there has been an important development of the original philosophy and method. In the case of phenetics, various biochemical techniques have used phenetic methods, but also, and importantly, “numerical cladistics” has diverged from phenetics and converged on cladistics. In the case of cladistics, “transformed cladistics” is regarded by some as an offshoot and rival to mainstream cladistics and by others as a logical development of the mainstream. These will be dealt with in Chapters 8 and 9. In Chapter 10, I shall attempt to sum up the present state of taxonomy and to draw conclusions that I regard as pivotal to the theme of this book. Phenetics Pheneticists used to trace their history back to Adanson, a contemporary of Linnaeus (Sokal and Sneath 1963, p. 50). [ABSTRACT FROM AUTHOR]

Extension of the mental test model American psychologists, as we noted in chapter 7, had set about redefining the psychological problem of individual differences in terms of a comparison of performances against a competitively defined standard. This redefinition appeared to be perfectly adapted to the administrative requirements of social institutions whose efficient functioning depended upon some kind of selection process that was rationally defensible. The kinds of tasks that best lent themselves to the measurement of individual differences in this sense were tasks with answers that were unambiguously right or wrong. Performance on such tasks could be readily arithmetized by counting right and wrong answers, a procedure that had long been conventionalized in the institution of school examinations. Improvements in the precision of such procedures, made possible by Galton's fundamental contributions, eventually led to the construction of normed intelligence tests. It is hardly a cause for surprise that educational institutions provided the setting in which intelligence tests proved themselves best adapted to administrative requirements. Transferred outside their home ground, their ability to predict future performance was much diminished, often to the point where their practical usefulness vanished altogether. This problem already emerged in the first major attempt at employing intelligence tests in the service of a noneducational institution, the U.S. Army in World War I. Most of the psychologists involved appear to have been convinced of the potential applicability of intelligence tests to military selection problems. However, although they were given considerable leeway and succeeded in testing well over a million men, the army does not seem to have found the results of this exercise particularly useful. [ABSTRACT FROM AUTHOR]