Showing papers by "Stony Brook University published in 1996"

Distribution Volume Ratios without Blood Sampling from Graphical Analysis of PET Data

Abstract: The distribution volume ratio (DVR), which is a linear function of receptor availability, is widely used as a model parameter in imaging studies. The DVR corresponds to the ratio of the DV of a receptor-containing region to a nonreceptor region and generally requires the measurement of an arterial input function. Here we propose a graphical method for determining the DVR that does not require blood sampling. This method uses data from a nonreceptor region with an average tissue-to-plasma efflux constant k2 to approximate the plasma integral. Data from positron emission tomography studies with [15C]raclopride (n = 20) and [11C]d-threo-methylphenidate ([11C]dMP) (n = 8) in which plasma data were taken and used to compare results from two graphical methods, one that uses plasma data and one that does not. k2 was 0.163 and 0.051 min−1 for [11C]raclopride and [11C]dMP, respectively. Results from both methods were very similar, and the average percentage difference between the methods was −0.11% for [11C]raclop...

Conceptual pacts and lexical choice in conversation.

Abstract: When people in conversation refer repeatedly to the same object, they come to use the same terms. This phenomenon, called lexical entrainment, has several possible explanations. Ahistorical accounts appeal only to the informativeness and availability of terms and to the current salience of the object's features. Historical accounts appeal in addition to the recency and frequency of past references and to partner-specific conceptualizations of the object that people achieve interactively. Evidence from 3 experiments favors a historical account and suggests that when speakers refer to an object, they are proposing a conceptualization of it, a proposal their addresses may or may not agree to. Once they do establish a shared conceptualization, a conceptual pact, they appeal to it in later references even when they could use simpler references. Over time, speakers simplify conceptual pacts and, when necessary, abandon them for new conceptualizations.

Catatonia. I. Rating scale and standardized examination.

Abstract: To facilitate the systematic description of catatonic signs, we developed a catatonia rating examination, rating scale and screening instrument. We constructed a 23-item rating scale and a truncated 14-item screening instrument using operationalized definitions of signs ascribed to catatonia in published sources. Inter-rater reliability was tested in 44 simultaneous ratings of 28 cases defined by the presence of ≥2 signs on the 14-item screen. Inter-rater reliability for total score on the rating scale was 0.93, and mean agreement of items was 88.2% (SD 9.9). Inter-rater reliability for total score on the screening instrument was 0.95, and mean agreement of items was 92.7% (SD 4.9). Diagnostic agreement was high based on criteria for catatonia put forth by other authors. Seven per cent (15/215) of consecutively admitted patients to an academic psychiatric in-patient facility met criteria for catatonia. It is concluded that catatonia is a distinct, moderately prevalent neuropsychiatric syndrome. The rating scale and screening instrument are reliable and valid. Their use facilitates diagnosis, treatment protocols, and cross-study comparisons.

Conservation of hippocampal memory function in rats and humans

Abstract: The hippocampus is critical to declarative memory in humans. This kind of memory involves associations among items or events that can be accessed flexibly to guide memory expression in various and even new situations. In animals, there has been controversy about whether the hippocampus is specialized for spatial memory or whether it mediates a general memory function, as it does in humans. To address this issue we trained normal rats and rats with hippocampal damage on non-spatial stimulus-stimulus associations, then probed the nature of their memory representations. We report here that normal rats demonstrated two forms of flexible memory expression, transitivity, the ability to judge inferentially across stimulus pairs that share a common element, and symmetry, the ability to associate paired elements presented in the reverse of training order. Rats with neurotoxic damage limited to the hippocampus demonstrated neither form of flexible expression, indicating that non-spatial declarative processing depends specifically on the hippocampus in animals as it does in humans.

Preserved neuron number in the hippocampus of aged rats with spatial learning deficits.

Abstract: Hippocampal neuron loss is widely viewed as a hallmark of normal aging. Moreover, neuronal degeneration is thought to contribute directly to age-related deficits in learning and memory supported by the hippocampus. By taking advantage of improved methods for quantifying neuron number, the present study reports evidence challenging these long-standing concepts. The status of hippocampal-dependent spatial learning was evaluated in young and aged Long-Evans rats using the Morris water maze, and the total number of neurons in the principal cell layers of the dentate gyrus and hippocampus was quantified according to the optical fractionator technique. For each of the hippocampal fields, neuron number was preserved in the aged subjects as a group and in aged individuals with documented learning and memory deficits indicative of hippocampal dysfunction. The findings demonstrate that hippocampal neuronal degeneration is not an inevitable consequence of normal aging and that a loss of principal neurons in the hippocampus fails to account for age-related learning and memory impairment. The observed preservation of neuron number represents an essential foundation for identifying the neurobiological effects of hippocampal aging that account for cognitive decline.

Inhibition of monoamine oxidase B in the brains of smokers

Abstract: The massive health problem associated with cigarette smoking is exacerbated by the addictive properties of tobacco smoke and the limited success of current approaches to cessation of smoking. Yet little is known about the neuropharmacological actions of cigarette smoke that contribute to smoking behaviour, or why smoking is so prevalent in psychiatric disorders and is associated with a decreased risk of Parkinson's disease. Here we report that brains of living smokers show a 40% decrease in the level of monoamine oxidase B (MAO B; EC 1.4.3.4) relative to non-smokers or former smokers. MAO B is involved in the breakdown of dopamine, a neurotransmitter implicated in reinforcing and motivating behaviours as well as movement. MAO B inhibition is therefore associated with enhanced activity of dopamine, as well as with decreased production of hydrogen peroxide, a source of reactive oxygen species. We propose that reduction of MAO B activity may synergize with nicotine to produce the diverse behavioural and epidemiological effects of smoking.

Double-Blind, Placebo-Controlled Study of the Effects of Carvedilol in Patients With Moderate to Severe Heart Failure The PRECISE Trial

Abstract: Background Carvedilol has improved the symptomatic status of patients with moderate to severe heart failure in single-center studies, but its clinical effects have not been evaluated in large, multicenter trials. Methods and Results We enrolled 278 patients with moderate to severe heart failure (6-minute walk distance, 150 to 450 m) and a left ventricular ejection fraction ≤0.35 at 31 centers. After an open-label, run-in period, each patient was randomly assigned (double-blind) to either placebo (n=145) or carvedilol (n=133; target dose, 25 to 50 mg BID) for 6 months, while background therapy with digoxin, diuretics, and an ACE inhibitor remained constant. Compared with placebo, patients in the carvedilol group had a greater frequency of symptomatic improvement and lower risk of clinical deterioration, as evaluated by changes in the NYHA functional class (P=.014) or by a global assessment of progress judged either by the patient (P=.002) or by the physician (P<.001). In addition, treatment with carvedilol...

Decreases in Dopamine Receptors but not in Dopamine Transporters in Alcoholics

Abstract: It has been hypothesized that ethanol's actions on the dopamine (DA) system may participate in addiction. The purpose of this study was to evaluate the DA system in the brain of alcoholics. We evaluated 10 alcoholics and 17 nonalcoholics using positron emission tomography and [11C]raclopride to measure DA D2 receptors. In addition, in 5 of the alcoholics and 16 of the nonalcoholics, we also measured DA transporters with [11C]d-threo methylphenidate. The ratio of the distribution volumes in striatum to that in cerebellum, which corresponds to Bmax/Kd + 1, was used as model parameter of DA D2 receptor and transporter availability. Dopamine D2 receptor availability (Bmax/Kd) was significantly lower in alcoholics (2.1 +/- 0.5) than in nonalcoholics (2.7 +/- 0.6) (p < 0.05) and was not correlated with days since last alcohol use. Alcoholics showed DA transporter values similar to those in nonalcoholics. The ratio of DA D2 receptor to transporter availability was significantly higher in nonalcoholics (1.4 +/- 0.1) than in alcoholics (1.1 +/- 0.1) (p < 0.005). Alcoholics showed significant reductions in D2 receptors (postsynaptic marker) but not in DA transporter availability (presynaptic marker) when compared with nonalcoholics. Because D2 receptors in striatum are mainly localized in gamma-aminobutyric acid (GABA) cells these results provide evidence of GABAergic involvement in the dopaminergic abnormalities seen in alcoholics.

A three-hybrid system to detect RNA-protein interactions in vivo

Abstract: RNA-protein interactions are pivotal in fundamental cellular processes such as translation, mRNA processing, early development, and infection by RNA viruses. However, in spite of the central importance of these interactions, few approaches are available to analyze them rapidly in vivo. We describe a yeast genetic method to detect and analyze RNA-protein interactions in which the binding of a bifunctional RNA to each of two hybrid proteins activates transcription of a reporter gene in vivo. We demonstrate that this three-hybrid system enables the rapid, phenotypic detection of specific RNA-protein interactions. As examples, we use the binding of the iron regulatory protein 1 (IRP1) to the iron response element (IRE), and of HIV trans-activator protein (Tat) to the HIV trans-activation response element (TAR) RNA sequence. The three-hybrid assay we describe relies only on the physical properties of the RNA and protein, and not on their natural biological activities; as a result, it may have broad application in the identification of RNA-binding proteins and RNAs, as well as in the detailed analysis of their interactions.

Molecular genetic bases of Salmonella entry into host cells

Abstract: Salmonella spp. can enter into non-phagocytic cells, a property that is essential for their pathogenicity. Recently, considerable progress has been made in the understanding of the molecular genetic bases of this process. It is now evident that Salmonella entry functions are largely encoded on a 35-40 kb region of the Salmonella chromosome located at centisome 63. The majority of the loci in this region encode components of a type III or contact-dependent secretion system homologous to those described in a variety of animal and plant-pathogenic bacteria as well as a number of proteins that require this system for their export to the extracellular environment. A somewhat unexpected finding has been the remarkable homology between the Salmonella and Shigella proteins that mediate the entry of these organisms into cultured epithelial cells.

Role of the Kv4.3 K+ Channel in Ventricular Muscle: A Molecular Correlate for the Transient Outward Current

Abstract: The expression of 15 different K + channels in canine heart was examined, and a new K + channel gene (Kv4.3), which encodes a rapidly inactivating K + current, is described. The Kv4.3 channel was found to have biophysical and pharmacological properties similar to the native canine transient outward current (I to ). The Kv4.3 gene is also expressed in human and rat heart. It is concluded that the Kv4.3 channel underlies the bulk of the I to in canine ventricular myocytes, and probably in human myocytes. Both the Kv4.3 and Kv4.2 channels are likely to contribute to the I to in rat heart, and differential expression of these two channels can account for observed differences in the kinetic properties of the I to in different regions of rat ventricle. There are significant differences in the pattern of K + channel expression in canine heart, compared with rat heart, and these differences may be an adaptation to the different requirements for cardiac function in mammals of markedly different sizes. It is possible that the much longer ventricular action potential duration observed in canine heart compared with rat heart is due, in part, to the lower levels of Kv1.2, Kv2.1, and Kv4.2 gene expression in canine heart.

Social constraints, intrusive thoughts, and depressive symptoms among bereaved mothers.

Abstract: The study examined how social constraints on discussion of a traumatic experience can interfere with cognitive processing of and recovery from loss. Bereaved mothers were interviewed at 3 weeks (T1), 3 months (T2), and 18 months (T3) after their infants' death. Intrusive thoughts at T1, conceptualized as a marker of cognitive processing, were negatively associated with talking about infant's death at T2 and T3 among socially constrained mothers. The reverse associations were found among unconstrained mothers. Controlling for initial level of distress, there was a positive relation between T1 intrusive thoughts and depressive symptoms over time among socially constrained mothers. However, higher levels of T1 intrusive thoughts were associated with a decrease in T3 depressive symptoms among mothers with unconstrained social relationships.

Molecular Evidence for Deep Precambrian Divergences Among Metazoan Phyla

Abstract: A literal reading of the fossil record suggests that the animal phyla diverged in an “explosion” near the beginning of the Cambrian period. Calibrated rates of molecular sequence divergence were used to test this hypothesis. Seven independent data sets suggest that invertebrates diverged from chordates about a billion years ago, about twice as long ago as the Cambrian. Protostomes apparently diverged from chordates well before echinoderms, which suggests a prolonged radiation of animal phyla. These conclusions apply specifically to divergence times among phyla; the morphological features that characterize modern animal body plans, such as skeletons and coeloms, may have evolved later.

Promotion and Tenure: Community and Socialization in Academe

Abstract: (1997). Promotion and Tenure: Community and Socialization in Academe. The Journal of Higher Education: Vol. 68, No. 5, pp. 591-593.

Tabled evaluation with delaying for general logic programs

Abstract: SLD resolution with negation as finite failure (SLDNF) reflects the procedural interpretation of predicate calculus as a programming language and forms the computational basis for Prolog systems. Despite its advantages for stack-based memory management, SLDNF is often not appropriate for query evaluation for three reasons: (a) it may not terminate due to infinite positive recursion; (b) it may be terminate due to infinite recursion through negation; and (c) it may repeatedly evaluate the same literal in a rule body, leading to unacceptable performance.We address all three problems for goal-oriented query evaluation of general logic programs by presenting tabled evaluation with delaying, called SLG resolution. It has three distinctive features:(i) SLG resolution is a partial deduction procedure, consisting of seven fundamental transformations. A query is transformed step by step into a set of answers. The use of transformations separates logical issues of query evaluation from procedural ones. SLG allows an arbitrary computation rule for selecting a literal from a rule body and an arbitrary control strategy for selecting transformations to apply.(ii) SLG resolution is sound and search space complete with respect to the well-founded partial model for all non-floundering queries, and preserves all three-valued stable models. To evaluate a query under differenc three-valued stable models, SLG resolution can be enhanced by further processing of the answers of subgoals relevant to a query.(iii) SLG resolution avoids both positive and negative loops and always terminates for programs with the bounded-term-size property. It has a polynomial time data complexity for well-founded negation of function-free programs. Through a delaying mechanism for handling ground negative literals involved in loops, SLG resolution avoids the repetition of any of its derivation steps.Restricted forms of SLG resolution are identified for definite, locally stratified, and modularly stratified programs, shedding light on the role each transformation plays.

Advocacy Coalitions, Policy Entrepreneurs, and Policy Change

Abstract: The advocacy coalition framework (AC) explains policy stability The policy entrepreneurship model (PE) explains dynamic policy change. Thus, augmenting the AC with insights from the PE provides a method of explaining a common empirical phenomenon: policy stability punctuated by dynamic policy change. This analytical strategy could be used to explore stability and change in many policy arenas. Here, we use it to interpret the background lo and dynamics of recent education policy reform in Michigan.

Intrinsic connections of the rat amygdaloid complex: Projections originating in the accessory basal nucleus

Abstract: The amygdaloid complex is involved in associational processes, such as the formation of emotional memories about sensory stimuli. However, the anatomical connections through which the different amygdaloid nuclei process incoming information and communicate with the other amygdaloid nuclei, is poorly understood. As part of an ongoing project aimed at elucidating the intrinsic connections of the rat amygdaloid complex, we injected the anterograde tracer PHA-L (Phaseolus vulgaris-leucoagglutinin) into different rostrocaudal levels of the basal nucleus of the amygdala in 21 rats and analyzed the distribution of labeled fibers and terminals throughout the amygdaloid complex. The connectional analysis, together with cytoarchitectonic observations, suggested that contrary to previous notions the basal nucleus in the rat has three divisions: magnocellular, intermediate, and parvicellular. The magnocellular division has heavy reciprocal connections with the lateral portion of the parvicellular division and the intermediate division projects weakly to the parvicellular division, whereas the projection from the medial portion of the parvicellular division to the intermediate division is heavy and the lateral and medial portions of the parvicellular division are only weakly interconnected, as are the magnocellular and intermediate divisions. The main intraamygdaloid targets of the basal nucleus projections are the nucleus of the lateral olfactory tract, the anterior amygdaloid area, the medial and capsular divisions of the central nucleus, the anterior cortical nucleus, and the amygdalohippocampal area. Our findings provide the most detailed understanding of the intra-amygdala connections of the basal nucleus to date and show that the connections within the basal nucleus and between the basal nucleus and other amygdaloid areas are more widespread and topographically organized than previously recognized.

Salmonella spp. are cytotoxic for cultured macrophages

Abstract: We have shown by a variety of microscopical and biochemical techniques that Salmonella spp. are cytotoxic for cultured J774A.1 and bone marrow-derived murine macrophages. The cytotoxicity is initially manifested by inhibition of membrane ruffling and macropinocytosis in infected macrophages, and is followed by cell death. Macrophages killed by Salmonella spp. exhibited features of apoptosis such as condensation and fragmentation of chromatin, membrane blebbing, and the presence of cytoplasmic nucleosomes and apoptotic bodies. Cytotoxicity does not require bacterial internalization as cytochalasin D, a drug that prevents bacterial uptake, did not prevent Salmonella-induced macrophage cell death. However, the cytotoxic effects are strictly dependent upon the expression of the invasion-associated Type III protein-secretion system encoded at centisome 63 of the Salmonella chromosome. Wild-type Salmonella typhimurium grown under conditions that do not allow optical expression of this system or strains of Salmonella carrying mutations in genes that encode components of this protein-secretion system were devoid of macrophage cytotoxicity. In addition, mutations in invJ, spaO, sipB, sipC and sipD, which encode proteins that are secreted via this secretion apparatus and are required for bacterial entry into non-phagocytic cells, also abolished the toxicity. In contrast, mutations in sipA and sptP, which encode secreted proteins that are not required for bacterial invasion, had no effect on macrophage cytotoxicity. These results indicate a close correlation between the mechanisms of bacterial internalization into non-phagocytic cells and those that lead to macrophage cytotoxicity. Host-adapted serotypes of Salmonella such as S. typhi, S. gallinarum and S. dublin were also toxic for murine macrophages, indicating that this virulence property is probably present in most Salmonella spp. and is not associated with the mechanisms responsible for host range.

Avalanche dynamics in evolution, growth, and depinning models

Abstract: The dynamics of complex systems in nature often occurs in terms of punctuations, or avalanches, rather than following a smooth, gradual path. A comprehensive theory of avalanche dynamics in models of growth, interface depinning, and evolution is presented. Specifically, we include the Bak-Sneppen evolution model, the Sneppen interface depinning model, the Zaitsev flux creep model, invasion percolation, and several other depinning models into a unified treatment encompassing a large class of far from equilibrium processes. The formation of fractal structures, the appearance of 1/f noise, diffusion with anomalous Hurst exponents, L\'evy flights, and punctuated equilibria can all be related to the same underlying avalanche dynamics. This dynamics can be represented as a fractal in d spatial plus one temporal dimension. The complex state can be reached either by tuning a parameter, or it can be self-organized. We present two exact equations for the avalanche behavior in the latter case. (1) The slow approach to the critical attractor, i.e., the process of self-organization, is governed by a ``gap'' equation for the divergence of avalanche sizes. (2) The hierarchical structure of avalanches is described by an equation for the average number of sites covered by an avalanche. The exponent \ensuremath{\gamma} governing the approach to the critical state appears as a constant rather than as a critical exponent. In addition, the conservation of activity in the stationary state manifests itself through the superuniversal result \ensuremath{\eta}=0. The exponent \ensuremath{\pi} for the L\'evy flight jumps between subsequent active sites can be related to other critical exponents through a study of ``backward avalanches.'' We develop a scaling theory that relates many of the critical exponents in this broad category of extremal models, representing different universality classes, to two basic exponents characterizing the fractal attractor. The exact equations and the derived set of scaling relations are consistent with numerical simulations of the above mentioned models. \textcopyright{} 1996 The American Physical Society.

Untangling Multiple Factors in Spatial Distributions: Lilies, Gophers, and Rocks

Abstract: Despite broad consensus on the power of experiments, correlational studies are still important in ecology, and may become more so as spatial studies proliferate. Conventional correlation analysis, however, (1) fundamentally conflicts with the basic ecological concept of limiting factors, and (2) ignores spatial structure in data, which can produce spuriously high correlations. Especially for field data, bivariate scattergrams often show factor—ceiling" distributions wherein data points are widely scattered beneath an upper limit, due to the action of other factors. Although most ecological information in such a graph resides in the upper limit, standard correlation/regression does not characterize such limits. If other factors have been measured, path analysis may be useful, but otherwise, direct description of ecological ceilings is desirable. Objective methods for doing so are barely known to ecologists; we review recent proposals for statistical testing and data display. For correcting correlations for spatial patchiness of the variables, another new technique has been proposed by Clifford, Richardson, and Hemon: by reducing the effective sample size to account for the autocorrelation it allows significance tests. We discuss these issues with reference to counts of glacier lily (Erythronium grandiflorum) seedlings, vegetative plants, and flowering plants in a square grid of 256 contiguous $2 \times 2$ m quadrats in subalpine meadow in western Colorado. We also measured soil moisture, pocket gopher activity, and soil rockiness. All six variables showed significant patchiness (spatial autocorrelation) at similar scales. The abundance of flowering plants was positively correlated with rockiness and negatively correlated with moisture and gopher activity. Although limited seed dispersal suggests that seedlings should be spatially associated with flowering plants, no such correlation existed: indeed, examination of the bivariate scatterplot suggests a negative association, in the particular and restricted sense that seedlings are abundant only in quadrats where flowering is low. We hypothesize that seed germination is higher in less rocky areas of deeper, moister soil than in the rocky areas where most seeds land, but that seedlings seldom reach maturity unless they are in a rocky refuge from predation. Results from path analysis are consistent with this hypothesis. Such an ecological situation should weaken natural selection on characters enhancing seed dispersal.

Stimulation of Membrane Ruffling and MAP Kinase Activation by Distinct Effectors of RAS

Abstract: The RAS guanine nucleotide binding proteins activate multiple signaling events that regulate cell growth and differentiation. In quiescent fibroblasts, ectopic expression of activated H-RAS (H-RASV12, where V12 indicates valine-12) induces membrane ruffling, mitogen-activated protein (MAP) kinase activation, and stimulation of DNA synthesis. A mutant of activated H-RAS, H-RASV12C40 (where C40 indicates cysteine-40), was identified that was defective for MAP kinase activation and stimulation of DNA synthesis, but retained the ability to induce membrane ruffling. Another mutant of activated H-RAS, H-RASV12S35 (where S35 indicates serine-35), which activates MAP kinase, was defective for stimulation of membrane ruffling and induction of DNA synthesis. Expression of both mutants resulted in a stimulation of DNA synthesis that was comparable to that induced by H-RASV12. These results indicate that membrane ruffling and activation of MAP kinase represent distinct RAS effector pathways and that input from both pathways is required for the mitogenic activity of RAS.

Phylogenetic performance of mitochondrial protein-coding genes in resolving relationships among vertebrates.

Abstract: A large number of studies in evolutionary biology utilize phylogenetic information obtained from mitochondrial DNA Researchers place trust in this molecule and expect it generally to be a reliable marker for addressing questions ranging from population genetics to phylogenies among distantly related lineages Yet, regardless of the phylogenetic method and weighting treatment, individual mitochondrial genes might potentially produce misleading evolutionary inferences and hence might not constitute an adequate representation neither of the entire mitochondrial genome nor of the evolutionary history of the organisms from which they are derived We investigated the performance of all mitochondrial protein-coding genes to recover two expected phylogenies of tetrapods and mammals According to these tests, mitochondrial protein-coding genes can be roughly classified into three groups of good (ND4, ND5, ND2, cytb, and COI), medium (COII, COIII, ND1, and ND6), and poor (ATPase 6, ND3, ATPase 8, and ND4L) phylogenetic performers in recovering these expected trees among phylogenetically distant relatives How general our findings are is unclear Simple length differences and rate differences between these genes cannot account for their different phylogenetic performance The phylogenetic performance of these mitochondrial genes might depend on various factors that play a role in determining the probability of discovering the correct phylogeny such as the density of lineage creation events in time, the phylogenetic "depth" of the question, lineage-specific rate heterogeneity, and the completeness of taxa representation

Dynamic view-dependent simplification for polygonal models

Abstract: Presents an algorithm for performing view-dependent simplifications of a triangulated polygonal model in real-time. The simplifications are dependent on viewing direction, lighting and visibility, and are performed by taking advantage of image-space, object-space and frame-to-frame coherences. A continuous level-of-detail representation for an object is first constructed off-line. This representation is then used at run-time to guide the selection of appropriate triangles for display. The list of displayed triangles is updated incrementally from one frame to the next. Our approach is more effective than the current level-of-detail-based rendering approaches for most scientific visualization applications where there are a limited number of highly complex objects that stay relatively close to the viewer.

A protein linkage map of Escherichia coli bacteriophage T7.

Abstract: Genome sequencing projects are predicting large numbers of novel proteins, whose interactions with other proteins must mediate the function of cellular processes. To analyse these networks, we used the yeast two-hybrid system on a genome-wide scale to identify 25 interactions among the proteins of Escherichia coli bacteriophage T7. Among these is a set of six interactions connecting proteins that function in DMA replication and DMA packaging. Remarkably, two genes, arranged such that one entirely overlaps the other and uses a different reading frame, encode interacting proteins. Several of the interactions reflect intramolecular associations of different domains of the same polypeptide, suggesting that the two-hybrid assay may be useful in the analysis of protein folding. This global approach to protein–protein interactions may be applicable to the analysis of more complex genomes whose sequences are becoming available.

Catatonia. II. Treatment with lorazepam and electroconvulsive therapy.

Abstract: Case material and retrospective studies support the use of both lorazepam and ECT in treating catatonia, but few prospective investigations exist and none employ quantitative monitoring of response. In this study we test their efficacy in an open, prospective protocol, and define a "lorazepam test' with predictive value for treatment. Twenty-eight patients with catatonia were treated systematically with parenteral and/or oral lorazepam for up to 5 days, and with ECT if lorazepam failed. Outcome was monitored quantitatively during the treatment phase with the Bush-Francis Catatonia Rating Scale (BFCRS). In 16 of 21 patients (76%) who received a complete trial of lorazepam (11 with initial intravenous challenge), catatonic signs resolved. A positive response to an initial parenteral challenge predicted final lorazepam response, as did length of catatonic symptoms prior to treatment. Neither demographic variables nor severity of catatonia predicted response to lorazepam. Four patients failing lorazepam responded promptly to ECT. It is concluded that lorazepam and ECT are effective treatments for catatonia. The rating scale has predictive value and displays sensitivity to change in clinical status.

Aggression Between Heterosexual Dating Partners An Examination of a Causal Model of Courtship Aggression

Abstract: The authors used structural equation analyses of data obtained from a survey of 345 college undergraduates (232 women, 113 men) to test a predictive model of dating aggression based on the background-situational model proposed by Riggs and O'Leary (1989). Results offer initial support for the background-situational model. Among men and women, dating aggression was directly related to the individual's attitudes about dating aggression, history of aggressive behavior, and conflict within the relationship. However, the predicted association between family of origin violence and attitudes toward aggression and general aggressive behavior was found only among women. Among men, the predictors explained more than 60% of the variance in the latent variable of relationship aggression; among women, 32% of the variance was explained. Discussion focuses on the utility of the background-situational model for understanding etiological factors of dating aggression and indentifying targets for interventions aimed at redu...