Showing papers by "University of California, San Diego published in 1987"
TL;DR: The relationship between co-integration and error correction models, first suggested in Granger (1981), is here extended and used to develop estimation procedures, tests, and empirical examples.
Abstract: The relationship between co-integration and error correction models, first suggested in Granger (1981), is here extended and used to develop estimation procedures, tests, and empirical examples. If each element of a vector of time series x first achieves stationarity after differencing, but a linear combination a'x is already stationary, the time series x are said to be co-integrated with co-integrating vector a. There may be several such co-integrating vectors so that a becomes a matrix. Interpreting a'x,= 0 as a long run equilibrium, co-integration implies that deviations from equilibrium are stationary, with finite variance, even though the series themselves are nonstationary and have infinite variance. The paper presents a representation theorem based on Granger (1983), which connects the moving average, autoregressive, and error correction representations for co-integrated systems. A vector autoregression in differenced variables is incompatible with these representations. Estimation of these models is discussed and a simple but asymptotically efficient two-step estimator is proposed. Testing for co-integration combines the problems of unit root tests and tests with parameters unidentified under the null. Seven statistics are formulated and analyzed. The critical values of these statistics are calculated based on a Monte Carlo simulation. Using these critical values, the power properties of the tests are examined and one test procedure is recommended for application. In a series of examples it is found that consumption and income are co-integrated, wages and prices are not, short and long interest rates are, and nominal GNP is co-integrated with M2, but not M1, M3, or aggregate liquid assets.
27,170 citations
TL;DR: Assaying the expression of luciferase provides a rapid and inexpensive method for monitoring promoter activity and is estimated to be from 30- to 1,000-fold more sensitive than assaying chloramphenicol acetyltransferase expression.
Abstract: The nucleotide sequence of the luciferase gene from the firefly Photinus pyralis was determined from the analysis of cDNA and genomic clones. The gene contains six introns, all less than 60 bases in length. The 5' end of the luciferase mRNA was determined by both S1 nuclease analysis and primer extension. Although the luciferase cDNA clone lacked the six N-terminal codons of the open reading frame, we were able to reconstruct the equivalent of a full-length cDNA using the genomic clone as a source of the missing 5' sequence. The full-length, intronless luciferase gene was inserted into mammalian expression vectors and introduced into monkey (CV-1) cells in which enzymatically active firefly luciferase was transiently expressed. In addition, cell lines stably expressing firefly luciferase were isolated. Deleting a portion of the 5'-untranslated region of the luciferase gene removed an upstream initiation (AUG) codon and resulted in a twofold increase in the level of luciferase expression. The ability of the full-length luciferase gene to activate cryptic or enhancerless promoters was also greatly reduced or eliminated by this 5' deletion. Assaying the expression of luciferase provides a rapid and inexpensive method for monitoring promoter activity. Depending on the instrumentation employed to detect luciferase activity, we estimate this assay to be from 30- to 1,000-fold more sensitive than assaying chloramphenicol acetyltransferase expression.
3,074 citations
TL;DR: It is demonstrated that AZT administration can decrease mortality and the frequency of opportunistic infections in a selected group of subjects with AIDS or AIDS-related complex, at least over the 8 to 24 weeks of observation in this study.
Abstract: We conducted a double-blind, placebo-controlled trial of the efficacy of oral azidothymidine (AZT) in 282 patients with the acquired immunodeficiency syndrome (AIDS) manifested by Pneumocystis carinii pneumonia alone, or with advanced AIDS-related complex. The subjects were stratified according to numbers of T cells with CD4 surface markers and were randomly assigned to receive either 250 mg of AZT or placebo by mouth every four hours for a total of 24 weeks. One hundred forty-five subjects received AZT, and 137 received placebo. When the study was terminated, 27 subjects had completed 24 weeks of the study, 152 had completed 16 weeks, and the remainder had completed at least 8 weeks. Nineteen placebo recipients and 1 AZT recipient died during the study (P less than 0.001). Opportunistic infections developed in 45 subjects receiving placebo, as compared with 24 receiving AZT. The base-line Karnofsky performance score and weight increased significantly among AZT recipients (P less than 0.001). A statistically significant increase in the number of CD4 cells was noted in subjects receiving AZT (P less than 0.001). After 12 weeks, the number of CD4 cells declined to pretreatment values among AZT recipients with AIDS but not amonG AZT recipients with AIDS-related complex. Skin-test anergy was partially reversed in 29 percent of subjects receiving AZT, as compared with 9 percent of those receiving placebo (P less than 0.001). These data demonstrate that AZT administration can decrease mortality and the frequency of opportunistic infections in a selected group of subjects with AIDS or AIDS-related complex, at least over the 8 to 24 weeks of observation in this study.
3,062 citations
01 Oct 1987
TL;DR: In this paper, the published experimental data of Hansson and Mehrbach et al. have been critically compared after adjustment to a common pH scale based upon total hydrogen ion concentration, and the results have been pooled to yield reliable equations that can be used to estimate pK1∗and pK2∗ for seawater media a salinities from 0 to 40 and at temperatures from 2 to 35°C.
Abstract: The published experimental data of Hansson and of Mehrbach et al. have been critically compared after adjustment to a common pH scale based upon total hydrogen ion concentration. No significant systematic differences are found within the overall experimental error of the data. The results have been pooled to yield reliable equations that can be used to estimate pK1∗and pK2∗ for seawater media a salinities from 0 to 40 and at temperatures from 2 to 35°C.
2,785 citations
TL;DR: Results strongly suggest that AP-1 is at the receiving end of a complex pathway responsible for transmitting the effects of phorbol ester tumor promoters from the plasma membrane to the transcriptional machinery.
2,773 citations
TL;DR: Using F-heaps, a new data structure for implementing heaps that extends the binomial queues proposed by Vuillemin and studied further by Brown, the improved bound for minimum spanning trees is the most striking.
Abstract: In this paper we develop a new data structure for implementing heaps (priority queues). Our structure, Fibonacci heaps (abbreviated F-heaps), extends the binomial queues proposed by Vuillemin and studied further by Brown. F-heaps support arbitrary deletion from an n-item heap in O(log n) amortized time and all other standard heap operations in O(1) amortized time. Using F-heaps we are able to obtain improved running times for several network optimization algorithms. In particular, we obtain the following worst-case bounds, where n is the number of vertices and m the number of edges in the problem graph: O(n log n + m) for the single-source shortest path problem with nonnegative edge lengths, improved from O(mlog(m/n+2)n);O(n2log n + nm) for the all-pairs shortest path problem, improved from O(nm log(m/n+2)n);O(n2log n + nm) for the assignment problem (weighted bipartite matching), improved from O(nmlog(m/n+2)n);O(mβ(m, n)) for the minimum spanning tree problem, improved from O(mlog log(m/n+2)n); where β(m, n) = min {i | log(i)n ≤ m/n}. Note that β(m, n) ≤ log*n if m ≥ n.Of these results, the improved bound for minimum spanning trees is the most striking, although all the results give asymptotic improvements for graphs of appropriate densities.
2,484 citations
TL;DR: A progressive alignment method that utilizes the Needleman and Wunsch pairwise alignment algorithm iteratively to achieve the multiple alignment of a set of protein sequences and to construct an evolutionary tree depicting their relationship is described.
Abstract: A progressive alignment method is described that utilizes the Needleman and Wunsch pairwise alignment algorithm iteratively to achieve the multiple alignment of a set of protein sequences and to construct an evolutionary tree depicting their relationship. The sequences are assumed a priori to share a common ancestor, and the trees are constructed from difference matrices derived directly from the multiple alignment. The thrust of the method involves putting more trust in the comparison of recently diverged sequences than in those evolved in the distant past. In particular, this rule is followed: “once a gap, always a gap”. The method has been applied to three sets of protein sequences: 7 superoxide dismutases, 11 globins, and 9 tyrosine kinase-like sequences. Multiple alignments and phylogenetic trees for these sets of sequences were determined and compared with trees derived by conventional pairwise treatments. In several instances, the progressive method led to trees that appeared to be more in line with biological expectations than were trees obtained by more commonly used methods.
2,014 citations
TL;DR: In this article, the authors examined the behavior of forecasts made from a co-integrated system as introduced by Granger (1981), Granger and Weiss (1983), and Engle and Granger (1987).
2,003 citations
TL;DR: Together the hMR and hGR provide unexpected functional diversity in which hormone-binding properties, target gene interactions, and patterns of tissue-specific expression may be used in a combinatorial fashion to achieve complex physiologic control.
Abstract: Low-stringency hybridization with human glucocorticoid receptor (hGR) complementary DNA was used to isolate a new gene encoding a predicted 107-kilodalton polypeptide. Expression studies demonstrate its ability to bind aldosterone with high affinity and to activate gene transcription in response to aldosterone, thus establishing its identity as the human mineralocorticoid receptor (hMR). This molecule also shows high affinity for glucocorticoids and stimulates a glucocorticoid-responsive promoter. Together the hMR and hGR provide unexpected functional diversity in which hormone-binding properties, target gene interactions, and patterns of tissue-specific expression may be used in a combinatorial fashion to achieve complex physiologic control.
1,854 citations
TL;DR: These scales are among the first measures of social support behaviors specific to dietary- and exercise-habit change and correlated with respective self-reported dietary and exercise habits, providing evidence of concurrent criterion-related validity.
1,405 citations
TL;DR: This article reviews the use of nonlinear regression in a practical and nonmathematical manner to demystify non linear regression so that both its power and its limitations will be appreciated.
Abstract: Many types of data are best analyzed by fitting a curve using nonlinear regression, and computer programs that perform these calculations are readily available. Like every scientific technique, however, a nonlinear regression program can produce misleading results when used inappropriately. This article reviews the use of nonlinear regression in a practical and nonmathematical manner to answer the following questions: Why is nonlinear regression superior to linear regression of transformed data? How does nonlinear regression differ from polynomial regression and cubic spline? How do nonlinear regression programs work? What choices must an investigator make before performing nonlinear regression? What do the final results mean? How can two sets of data or two fits to one set of data be compared? What problems can cause the results to be wrong? This review is designed to demystify nonlinear regression so that both its power and its limitations will be appreciated.
TL;DR: The 50 kd activator protein 2 (AP-2) as discussed by the authors is another enhancer-binding protein interacting with the human metallothionein IIA (hMT-IIA) gene control region.
TL;DR: Continuous intracerebral infusion of NGF over a period of four weeks can partly reverse the cholinergic cell body atrophy and improve retention of a spatial memory task in behaviourally impaired aged rats.
Abstract: In aged rodents, impairments in learning and memory have been associated with an age-dependent decline in forebrain of cholinergic function, and recent evidence indicates that the cholinergic neurons in the nucleus basalis magnocellularis, the septal-diagonal band area and the striatum undergo age-dependent atrophy. Thus, as in Alzheimer-type dementia in man, degenerative changes in the forebrain cholinergic system may contribute to age-related cognitive impairments in rodents. The cause of these degenerative changes is not known. Recent studies have shown that the central cholinergic neurons in the septal-diagonal band area, nucleus basalis and striatum are sensitive to the neurotrophic protein nerve growth factor (NGF). In particular, intraventricular injections or infusions of NGF in young adult rats have been shown to prevent retrograde neuronal cell death and promote behavioural recovery after damage to the septo-hippocampal connections. It is so far not known, however, whether the atrophic cholinergic neurons in aged animals are responsive to NGF treatment. We report here that continuous intracerebral infusion of NGF over a period of four weeks can partly reverse the cholinergic cell body atrophy and improve retention of a spatial memory task in behaviourally impaired aged rats.
TL;DR: Treatment with probucol significantly reduced the rate of development of fatty-streak lesions even though plasma cholesterol levels were no lower than lovastatin-treated (control) rabbits.
Abstract: It has been postulated that low density lipoprotein (LDL) becomes fully atherogenic only if it first undergoes oxidative modification. The oxidatively modified form, but not native LDL, is recognized by the acetyl-LDL or "scavenger" receptor and could, therefore, be taken up rapidly by tissue macrophages to generate the fatty-streak lesion of atherosclerosis. However, there is thus far very little direct evidence for oxidative modification in vivo. The studies reported here take advantage of the fact that probucol is an effective antioxidant transported in lipoproteins, including LDL, and blocks the oxidative modification of LDL in vitro. We now show that the rate of degradation of LDL in the macrophage-rich fatty-streak lesions of the LDL receptor-deficient rabbit treated with probucol (1% by weight in the diet) is reduced to about one-half of that in the lesions of receptor-deficient rabbits not given probucol (but matched for plasma cholesterol levels). In contrast, the rates of degradation in the nonlesioned areas of the aorta were no different in probucol-treated and control animals. Most of the LDL degradation in fatty-streak lesions takes place in macrophages, whereas in nonlesioned aorta, which contains very few macrophages, the degradation is almost exclusively in endothelial cells and smooth muscle cells. Thus, the results are compatible with the postulate that the native LDL taken up and degraded by foam cells in the developing fatty-streak lesions was in part first converted to a form recognized by the scavenger receptor (by oxidative or analogous modification). Finally, and most importantly, we show that treatment with probucol significantly reduced the rate of development of fatty-streak lesions even though plasma cholesterol levels were no lower than lovastatin-treated (control) rabbits.
TL;DR: This paper found that students responded to stimulus foils that were homophonic to category exemplars (e.g., ROWS for the category A FLOWER) than when they responded to spelling control foils.
Abstract: Skilled readers generally are assumed to make little or no use of words’ phonological features in visual word identification. Contrary to this assumption, college students’ performance in the present reading experiments showed large effects of stimulus word phonology. In Experiments 1 and 2, these subjects produced larger false positive error rates in a semantic categorization task when they responded to stimulus foils that were homophonic to category exemplars (e.g., ROWS for the category A FLOWER) than when they responded to spelling control foils. Additionally, in Experiment 2, this homophony effect was found under brief-exposure pattern-masking conditions, a result consistent with the possibility that phonology is an early source of constraint in word identification. Subjects did, however, correctly reject most homophone foils in Experiments 1 and 2. Experiment 3 investigated the source of this ability. The results of Experiment 3 suggest that subjects detected homophone impostors, such as ROWS, by verifying target foil spellings against their knowledge of the correct spellings of category exemplars, such as ROSE.
TL;DR: A reflection observed on multi-channel seismic profiles along and across the East Pacific Rise between 8°50′ N and 13°30′ N is interpreted to arise from the top of a crustal magma chamber located 1.2-2.4 km below the sea floor as discussed by the authors.
Abstract: A reflection observed on multi-channel seismic profiles along and across the East Pacific Rise between 8°50′ N and 13°30′ N is interpreted to arise from the top of a crustal magma chamber located 1.2–2.4 km below the sea floor. The magma chamber is quite narrow (<4 – 6 km wide), but can be traced as a nearly continuous feature for tens of kilometres along the rise axis.
TL;DR: Aging affects the frontal and temporal lobes more than the parietal; the salient change is shrinkage of large neurons with consequently increasing numbers of small neurons in the midfrontal and superior temporal areas.
Abstract: Fifty-one brains from clinically and neuropathologically normal individuals ranging in age from 24 to 100 years were studied to determine what changes occur in neocortical neuroectodermal cell populations as a function of normal aging. Twenty-m-thick sections from the midfrontal, superior temporal, and inferior parietal areas were examined with an image-analysis apparatus with combined manual and automatic editing capacity. Neuroectodermal cells were counted, measured, and assigned to one of ten categories, which were later summarized in three: large neurons (<90 m2), small neurons (41 to 90 m2), and glia (5 to 40 m2). Determinations were also made of brain weight, cortical thickness, neuronal density, neuron--glia ratio, and percentage of cell area. The results showed statistically significant age-related decrements in the following values: brain weight, cortical thickness in the midfrontal and superior temporal areas, large neurons in all three areas, and the neuron--glia ratio in the midfrontal and inferior parietal areas. The total number of neurons, neuronal density, and percentage of cell area were all unchanged. Increasing with age were the number of small neurons in the midfrontal cortex and glia in the midfrontal and superior temporal areas. The following conclusions were drawn: (1) Aging affects the frontal and temporal lobes more than the parietal; the salient change is shrinkage of large neurons with consequently increasing numbers of small neurons; (2) constant neuronal density coupled with diminished cortical volume (decreased brain weight and cortical thinning) indicate that there is some neuronal loss with age, but it is of much lesser magnitude than previously supposed; and (3) the number of glia increases with age.
TL;DR: Biochemical fractionation and immunofluorescence studies demonstrate that the majority of the RB protein is located within the nucleus, suggesting that the RB gene product may function in regulating other genes within the cell.
Abstract: The human gene (RB) that determines susceptibility to hereditary retinoblastoma has been identified recently by molecular genetic techniques. Previous results indicate that complete inactivation of the RB gene is required for tumour formation. As a 'cancer suppressor' gene, RB thus functions in a manner opposite to that of most other oncogenes. Sequence analysis of RB complementary DNA clones demonstrated a long open reading frame encoding a hypothetical protein with features suggestive of a DNA-binding function. To further substantiate and identify the RB protein, we have prepared rabbit antisera against a trypE-RB fusion protein. The purified anti-RB IgG immunoprecipitates a protein doublet with apparent relative molecular mass (Mr) of 110,000-114,000. The specific protein(s) are present in all cell lines expressing normal RB mRNA, but are not detected in five retinoblastoma cell lines examined. The RB protein can be metabolically labelled with 32P-phosphoric acid, indicating that it is a phosphoprotein. Biochemical fractionation and immunofluorescence studies demonstrate that the majority of the protein is located within the nucleus. Furthermore, the protein can be retained by and eluted from DNA-cellulose columns, suggesting that it is associated with DNA binding activity. Taken together, these results imply that the RB gene product may function in regulating other genes within the cell.
TL;DR: Stable transformants have a dramatic reduction in the amount of MHC A protein, grow slowly, and generate giant multinucleated progeny, indicating an impairment in cytokinesis, and expression of the endogenous mhcA messenger RNA can be increased relative to expression of antisense RNA.
Abstract: The role of myosin in the contraction of striated muscle cells is well known, but its importance in nonmuscle cells is not yet clear. The function of myosin in Dictyostelium discoideum has been investigated by isolating cells which specifically lack myosin heavy chain (MHC A) protein. Cells were transformed with a vector encoding RNA complementary to mhcA messenger RNA (antisense RNA). Stable transformants have a dramatic reduction in the amount of MHC A protein, grow slowly, and generate giant multinucleated progeny, indicating an impairment in cytokinesis. Surprisingly, the cells adhere to surfaces, extend pseudopods and are capable of ameboid locomotion. The developmental sequence that is initiated by starving cells is severely impaired by the lack of myosin. The cells are unable to form multicellular aggregates normally and do not undergo subsequent morphogenesis. By changing the food source from liquid medium to bacteria, expression of the endogenous mhcA messenger RNA can be increased relative to expression of antisense RNA. When grown in this way, the transformed cells accumulate MHC A protein, remain mononucleate, and proceed through development normally.
TL;DR: The L\'evy walk as discussed by the authors is a random walk with nonlocal memory coupled in space and in time in a scaling fashion, which results in enhanced diffusion, i.e., diffusion that grows as
Abstract: We introduce a stochastic process called a L\'evy walk which is a random walk with a nonlocal memory coupled in space and in time in a scaling fashion. L\'evy walks result in enhanced diffusion, i.e., diffusion that grows as ${\mathrm{t}}^{\mathrm{\ensuremath{\alpha}}}$,\ensuremath{\alpha}g1. When applied to the description of a passive scalar diffusing in a fluctuating fluid flow the model generalizes Taylor's correlated-walk approach. It yields Richardson's ${\mathrm{t}}^{3}$ law for the turbulent diffusion of a passive scalar in a Kolmogorov -(5/3) homogeneous turbulent flow and also gives the deviations from the (5/3) exponent resulting from Mandelbrot's intermittency. The model can be extended to studies of chemical reactions in turbulent flow.
TL;DR: Almost all large RNA virus clonal populations are quasispecies collections of differing, related genomes, which presents daunting challenges for the design of effective vaccines for the control of diseases caused by rapidly evolving RNA virus populations.
Abstract: The high error rate inherent in all RNA synthesis provides RNA virus genomes with extremely high mutation rates. Thus nearly all large RNA virus clonal populations are quasispecies collections of differing, related genomes (14, 49). These rapidly mutating populations can remain remarkably stable under certain conditions of replication. Under other conditions, virus-population equilibria become disturbed, and extremely rapid evolution can result. This extreme variability and rapid evolution can cause severe problems with previously unknown virus diseases (such as AIDS). It also presents daunting challenges for the design of effective vaccines for the control of diseases caused by rapidly evolving RNA virus populations.
TL;DR: It is concluded that the tyrosine kinase activity of the EGF receptor is essential for the diverse biochemical effects of EGF, including rapid alterations in intracellular calcium, activation of gene transcription, receptor down-regulation and the ultimate stimulatory effects on cell proliferation.
Abstract: The epidermal growth factor (EGF) receptor is a transmembrane glycoprotein of relative molecular mass 170,000 with intrinsic ligand-dependent protein tyrosine kinase activity1–6. Binding of EGF to its receptor activates a number of immediate biochemical processes, such as alterations of intracellular free calcium, pH, and increased transcription of several responsive genes, which usually culminate many hours later in DNA replication and cell division7–14. Abolishing the tyrosine kinase activity of three related oncogenes, v-src, v-mos, and v-fps, eliminates their capacity to transform cells15–17. Several reports have suggested that specific aspects of EGF receptor function are independent of the intrinsic tyrosine kinase activity18,19; however, these studies used an antibody against EGF receptor which failed to activate phosphoryla-tion of exogenous substrates18 and an insertional mutation in the EGF receptor tyrosine kinase domain which had not been shown to abolish protein kinase activity in cells19. Because many transmembrane receptors interact with intrinsic membrane proteins to activate second messenger systems, it is important to resolve experimentally whether mechanisms, in addition to activation of the intrinsic tyrosine kinase activity, mediate some EGF actions. From functional analyses of an EGF receptor containing a single amino-acid mutation at a site required for phosphate transfer from ATP, we conclude that the tyrosine kinase activity of the EGF receptor is essential for the diverse biochemical effects of EGF, including rapid alterations in intracellular calcium, activation of gene transcription, receptor down-regulation and the ultimate stimulatory effects on cell proliferation.
TL;DR: Event-related brain potentials were recorded during an incidental learning paradigm and showed that the ERP differences based on later memory performance did not necessarily arise from amplitude variation in P3 waves that occurred at the same time.
TL;DR: It is postulate that central nervous system involvement by HIV may begin early in the course of AIDS and cause mild cognitive deficits in otherwise asymptomatic persons.
Abstract: Although a high prevalence of central nervous system disease is seen in persons with the acquired immunodeficiency syndrome (AIDS), the natural history of brain involvement with human immunodeficiency virus (HIV) remains poorly understood. Neuropsychologic evaluations of 55 ambulatory homosexual men revealed abnormalities in 13 of 15 with AIDS, 7 of 13 [corrected] with AIDS-related complex, 7 of 16 [corrected] with HIV-seropositivity only, and 1 of 11 with HIV-seronegativity. Common neuropsychologic problems included impaired abstracting ability, learning difficulties, and slowed speed of information processing. Magnetic resonance imaging had abnormal findings in 9 of 13 patients with AIDS and 5 of 10 patients with AIDS-related complex who were available for scans. The commonest abnormalities were sulcal and ventricular enlargement and bilateral patchy areas of high signal intensity in the white matter. We postulate that central nervous system involvement by HIV may begin early in the course of AIDS and cause mild cognitive deficits in otherwise asymptomatic persons.
TL;DR: A cell-free system derived from Xenopus eggs that reconstitutes nuclear structure around an added protein-free substrate (bacteriophage lambda DNA) is developed, indicating that during reconstitution nuclear organization is assembled one level at a time.
TL;DR: The findings suggest that populations of these shore fishes are in at least a quasi‐equilibrium with respect to migration, mutation, and genetic drift.
Abstract: Ten species of marine shore fishes with a wide range of life-history strategies were collected from four areas in southern California, U.S.A., and Baja California, Mexico, and examined for patterns of genetic differentiation. Multilocus D and FST values (based on 32-42 presumptive gene loci in each species) were both negatively correlated with estimated dispersal capability. These results were robust to variations in the number and type of loci used in the analysis and are compatible with the hypothesis that levels of genetic differentiation in these shore fishes are determined primarily by gene flow and genetic drift. There is no a priori reason to expect the observed correlation to result from natural selection or historical factors. The findings thus suggest that populations of these shore fishes are in at least a quasi-equilibrium with respect to migration, mutation, and genetic drift. Present data were also used to compare estimates of mNe obtained by three different methods. Estimates based on FST values calculated by the methods of Nei and Chesser (FST(N) ) and Weir and Cockerham (FST(W) ) were highly correlated, but FST(N) ≤ FST(W) for every species, leading to generally higher mNe estimates for Nei and Chesser's method. Estimates of mNe based on the frequency of private alleles (Slatkin, 1985a) were not as strongly correlated with dispersal capability as were FST and D values. A low incidence of private alleles in many species may be responsible for this relatively weak correlation and may limit the general usefulness of Slatkin's method. In spite of their sensitivity to natural selection, FST and D may be better indicators of relative gene flow levels for high gene flow species.
TL;DR: Measurement of hCG and hCG‐alpha in maternal serum samples can be used as a screening procedure for detecting pregnancies at risk for fetal chromosome abnormalities and both elevated and depressed gonadotropin levels resulted in detection of 76% of abnormal pregnancies.
Abstract: The alpha subunit of human chorionic gonadotropin (alpha-hCG), human chorionic gonadotropin (hCG) and alpha fetoprotein (AFP) were measured in the serum of 25 women with chromosomally abnormal fetuses between 18 and 25 weeks of gestation and in 74 normal pregnancies. AFP levels less than 0.5 multiples of the median (MoM) or greater than 2.5 MoM were observed in 24 per cent of the abnormal pregnancies and in 6.76 per cent of the normal pregnancies. A low concentration of hCG ( 2.5 MoM) was observed in 56 per cent of abnormals and in 1.35 per cent of normals. Elevated hCG-alpha (>2.5 MoM) was observed in 28 per cent of abnormals and in none of the normals. Determination of elevated levels of hCG-alpha or hCG resulted in detection of 68 per cent of pregnancies with chromosomally abnormal fetuses with a false positive rate of 1.35 per cent. Determination of both elevated and depressed gonadotropin levels resulted in detection of 76 per cent of abnormal pregnancies with a false positive rate of 4.05 per cent. Measurement of hCG and hCG-alpha in maternal serum samples can be used as a screening procedure for detecting pregnancies at risk for fetal chromosome abnormalities.
TL;DR: The increased rate of prematurity, intrauterine growth retardation, and per inatal complications associated with perinatal exposure to cocaine or methamphetamine was greater than that predicted by coexisting risk factors and was consistent with the pharmacologic properties of these drugs.
TL;DR: The goal of the proposed studies is to characterize the effects of noradrenergic (NA) afferents on cortical information processing and examine the relationship between the intensity of LC neuronal activity and rates of norepinephrine release in neocortex and hippocampus during manipulation of LC activity.
Abstract: : The goal of the proposed studies is to characterize the effects of noradrenergic (NA) afferents on cortical information processing. our previous studies indicate that the primate locus coeruleus (LC) system, originating in the pontine brainstem, innervates neocortex more densely than previously thought, exhibiting highly specific patterns in terms of the regional and laminar distribution of its axons. our previous neurophysiological observations suggest that this system imposes state-related modulatory effects on thalamo- cortical and cortico-cortical systems. The proposed studies have the following Specific Aims: (1) To examine, in monkeys, the effects of manipulating the LC-NA system on ERPs, EEG characteristics, and associated behaviors in operant paradigms that utilize visual or auditory cues; (2) To correlate the activities of individual monkey LC-NA neurons with cortical neuronal activity and the measures utilized in Aim 1; (3) To extend our preliminary observation that activation of the LC by local drug infusion, in halothane-anesthetized rats, produces EEG signs of cortical and hippocampal activation; (4) To examine the relationship between the intensity of LC neuronal activity and rates of norepinephrine release in neocortex and hippocampus by performing microdialysis in these forebrain terminal regions in anesthetized rats during manipulation of LC activity.