Optimizing purebred selection for crossbred performance using QTL with different degrees of dominance

A method was developed to optimize simultaneous selection for a quantitative trait with a known QTL within a male and a female line to maximize crossbred performance from a two-way cross. Strategies to maximize cumulative discounted response in crossbred performance over ten generations were derived by optimizing weights in an index of a QTL and phenotype. Strategies were compared to selection on purebred phenotype. Extra responses were limited for QTL with additive and partial dominance effects, but substantial for QTL with over-dominance, for which optimal QTL selection resulted in differential selection in male and female lines to increase the frequency of heterozygotes and polygenic responses. For over-dominant QTL, maximization of crossbred performance one generation at a time resulted in similar responses as optimization across all generations and simultaneous optimal selection in a male and female line resulted in greater response than optimal selection within a single line without crossbreeding. Results show that strategic use of information on over-dominant QTL can enhance crossbred performance without crossbred testing.     

Multicenter evaluation of the performance and clinical utility in longitudinal monitoring of the Bayer Immuno 1 complexed PSA assay.

We conducted a multicenter evaluation of the analytical and clinical performance of the automated Bayer Immuno 1 complexed PSA (cPSA) assay, and compared assay performance to the Bayer Immuno 1 PSA assay. We sought to determine whether measurements of cPSA could be of clinical utility in the management of patients with prostate cancer. Results of the 10-day imprecision across three evaluation sites produced total CV < 2.50% and an analytical sensitivity of 0.02 microgram/L. There was an increased trend in clinical sensitivity for prostate cancer with increasing stage of disease (71-86%). Clinical specificity for patients with benign urogenital disease was 74.8%, and for other nonprostate diseases ranged from 91.1-100%. Retrospective serial monitoring of 155 patients with prostate cancer demonstrated concordance of cPSA measurements to clinical status for 97% of the patients analyzed. Results from the clinical studies using the Bayer Immuno 1 cPSA assay were comparable to results obtained with the Bayer Immuno 1 PSA assay. The Bayer Immuno 1 cPSA assay demonstrates analytical performance and clinical effectiveness in the management of prostate cancer patients during the course of disease and therapy.     

Solid tumor preparation for clinical application of flow cytometry

Intense interest in advanced squamous cell cancers of the head and neck (SCC of H&N) has resulted from the recent progress made in tumor responses with chemotherapy and radiotherapy. Unfortunately, the response patterns and clinical outcome of such patients are not adequately predicted on an individual patient basis using clinical parameters or conventional morphology. The study of flow cytometrically determined cellular parameters in such tumors is therefore of interest, but is hindered by inadequate tumor preparative technology. The previous article (10) in this journal describes the use of a murine SCC tumor, LC12, which was employed for comparative testing and determination of optimum techniques of preparation for this tumor. This report describes the application of these techniques to 144 specimens of human SCC of H&N. The mean total yield for these specimens is 7.4 X 10(7) cells/g of tissue. The mean viable enzymatic yield (3.3 X 10(7) cells/g) was higher than the mean viable mechanical yield (2.0 X 10(7) cells/g) except when lymph nodes were the source of the specimen (5.4 X 10(7) cells/g). The mean dye exclusion viability from enzymatically dissociated specimens were above 90%. Significant aneuploidal subpopulation losses were evident in mechanically dissociated and enucleated specimens. 65% of the enzymatically dissociated specimens were successfully cultured with a mean cloning efficiency of 2.1 X 10(-3). Preparative techniques derived from comparative testing with a murine standard tumor have been successfully applied to 144 specimens of SCC of H&N with resultant high yields and excellent viability. Technical problems detected during the preliminary testing with LC12 were confirmed in the human tumors.     

Effect of postnatal development on calcium currents and slow charge movement in mammalian skeletal muscle

Single- (whole-cell patch) and two-electrode voltage-clamp techniques were used to measure transient (Ifast) and sustained (Islow) calcium currents, linear capacitance, and slow, voltage-dependent charge movements in freshly dissociated fibers of the flexor digitorum brevis (FDB) muscle of rats of various postnatal ages. Peak Ifast was largest in FDB fibers of neonatal (1-5 d) rats, having a magnitude in 10 mM external Ca of 1.4 +/- 0.9 pA/pF (mean +/- SD; current normalized by linear fiber capacitance). Peak Ifast was smaller in FDB fibers of older animals, and by approximately 3 wk postnatal, it was so small as to be unmeasurable. By contrast, the magnitudes of Islow and charge movement increased substantially during postnatal development. Peak Islow was 3.6 +/- 2.5 pA/pF in FDB fibers of 1-5-d rats and increased to 16.4 +/- 6.5 pA/pF in 45-50-d-old rats; for these same two age groups, Qmax, the total mobile charge measurable as charge movement, was 6.0 +/- 1.7 and 23.8 +/- 4.0 nC/microF, respectively. As both Islow and charge movement are thought to arise in the transverse-tubular system, linear capacitance normalized by the area of fiber surface was determined as an indirect measure of the membrane area of the t-system relative to that of the fiber surface. This parameter increased from 1.5 +/- 0.2 microF/cm2 in 2-d fibers to 2.9 +/- 0.4 microF/cm2 in 44-d fibers. The increases in peak Islow, Qmax, and normalized linear capacitance all had similar time courses. Although the function of Islow is unknown, the substantial postnatal increase in its magnitude suggests that it plays an important role in the physiology of skeletal muscle.     

Benzodiazepine Receptor Binding in Cerebellar Cortex: Observations in Olivopontocerebellar Atrophy

Benzodiazepine receptor binding was measured in cerebellar cortex of 15 patients with dominantly inherited olivopontocerebellar atrophy (OPCA). The majority of these patients had a moderate to marked Purkinje cell loss, as judged by the lowered levels of dentate nucleus gamma-aminobutyric acid (GABA), a marker of Purkinje cells. Despite the reduction in Purkinje cell number cerebellar cortical benzodiazepine receptor density was either normal or slightly elevated in the OPCA patients. These results are in contrast to the findings in a mutant strain of mice deficient in Purkinje cells in which the concentration of benzodiazepine receptors in cerebellum is greatly reduced. Our data indicate that in the human, cerebellar cortical benzodiazepine receptors are either not significantly associated with Purkinje cells or that in OPCA Purkinje cell loss triggers a de novo synthesis of extra benzodiazepine binding sites. It is concluded that, in contrast with the rodent, in the human benzodiazepine receptor binding may not serve as a marker for cerebellar Purkinje cells.     

Characterization of the solubilized and reconstituted ATP-dependent vesicular glutamate uptake system

We have previously provided evidence for ATP-dependent glutamate uptake into synaptic vesicles, and, based upon the unique properties of the vesicular uptake system, we have proposed that the vesicular glutamate translocator plays a crucial role in selecting glutamate for neurotransmission. In this study, we have solubilized the vesicular glutamate uptake system, proposed to consist of at least a glutamate translocator and a proton pump Mg-ATPase, from rat brain synaptic vesicles, and reconstituted the functional ATP-dependent glutamate uptake system into liposomes. The glutamate uptake in the reconstituted system is dependent upon ATP, markedly potentiated by low millimolar concentrations of chloride and inhibited by agents known to dissipate electrochemical proton gradients. Moreover, it exhibited low affinity for glutamate (Km = 2 mM), yet high specificity for glutamate; thus, it did not recognize aspartate and other agents known to interact with glutamate receptors. These properties are indistinguishable from those observed in intact synaptic vesicles. The solubilized functional components of the glutamate uptake system, alone or as a complex, have been estimated to have a Stokes radius in the range of 69 to 84 A. The reconstitution experiments described here provide a functional assay for the solubilized vesicular glutamate uptake system and represent an initial step towards the purification of the glutamate translocator.     

Down''s Syndrome Individuals Begin Life with Normal Levels of Brain Cholinergic Markers

We measured the activities of the cholinergic marker enzymes choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) in autopsied brains of seven infants (age range 3 months to 1 year) with Down's syndrome (DS), a disorder in which virtually all individuals will develop by middle age the neuropathological changes of Alzheimer's disease accompanied by a marked brain cholinergic reduction. When compared with age-matched controls cholinergic enzyme activity was normal in all brain regions of the individuals with infant DS with the exception of above-normal activity in the putamen (ChAT) and the occipital cortex (AChE). Our neurochemical observations suggest that DS individuals begin life with a normal complement of brain cholinergic neurons. This opens the possibility of early therapeutic intervention to prevent the development of brain cholinergic changes in patients with DS.     

Brain S-Adenosylmethionine Levels Are Severely Decreased in Alzheimer's Disease

Abstract: S -Adenosylmethionine is an essential ubiquitous metabolite central to many biochemical pathways, including transmethylation and polyamine biosynthesis. Reduced CSF S -adenosylmethionine levels in Alzheimer's disease have been reported; however, no information is available regarding the status of S -adenosylmethionine or S -adenosylmethionine-dependent methylation in the brain of patients with this disorder. S -Adenosylmethionine concentrations were measured in postmortem brain of 11 patients with Alzheimer's disease. We found decreased levels of S -adenosylmethionine (−67 to −85%) and its demethylated product S -adenosylhomocysteine (−56 to −79%) in all brain areas examined (cerebral cortical subdivisions, hippocampus, and putamen) as compared with matched controls (n = 14). S -Adenosylmethionine and S -adenosylhomocysteine levels were normal in occipital cortex of patients with idiopathic Parkinson's disease (n = 10), suggesting that the decreased S -adenosylmethionine levels in Alzheimer's disease are not simply a consequence of a chronic, neurodegenerative condition. Reduced S -adenosylmethionine levels could be due to excessive utilization in polyamine biosynthesis. The severe reduction in levels of this essential biochemical substrate would be expected to compromise seriously metabolism and brain function in patients with Alzheimer's disease and may provide the basis for the observations of improved cognition in some Alzheimer's patients following S -adenosylmethionine therapy.     

Polyamines in Human Brain: Regional Distribution and Influence of Aging

Abstract: Depolarization of adult rat forebrain slices with veratrine induced the release of excitatory amino acids (glutamate and aspartate), the synthesis of nitric oxide (NO), and increases in cyclic GMP (cGMP). The NO synthase inhibitors N ^ω-monomethyl- l -arginine and N ^ω-nitro- l -arginine methyl ester decreased the release of NO and the levels of cGMP without affecting the release of excitatory amino acids. In contrast, the antiepileptic drug lamotrigine inhibited the release of excitatory amino acids and of NO, and decreased the levels of cGMP without causing a significant direct inhibition of the NO synthase. Furthermore, the synthesis of NO and the increases in cGMP induced by veratrine were partially blocked by the N -methyl- d -aspartate (NMDA) receptor antagonist MK-801 but not by 6-nitro-7-sulphamobenzo( f )quinoxaline-2,3-dione, a non-NMDA receptor antagonist. Neither of these compounds inhibited directly the NO synthase or the release of excitatory amino acids. Thus, these three types of compound act as an inhibitor of voltage-sensitive sodium channels (lamotrigine), as a receptor antagonist (MK-801), or as direct inhibitors of the NO synthase, to block the pathway leading to increased cGMP after veratrine depolarization. It is likely that some of the pharmacological and therapeutic actions shared by these three types of compound are, at least in part, a consequence of inhibition of the synthesis of NO.