Showing papers by "University of Illinois at Chicago published in 1992"
1,467 citations
TL;DR: This study suggests that high doses of calcium-channel blockers in patients with primary pulmonary hypertension who respond with reductions in pulmonary-artery pressure and pulmonary vascular resistance may improve survival over a five-year period.
Abstract: Background. Primary pulmonary hypertension is a progressive, fatal disease of unknown cause. Vasodilator drugs have been used as a treatment, but their efficacy is uncertain. Methods. We treated 64 patients with primary pulmonary hypertension with high doses of calcium-channel blockers. Patients who responded to treatment (defined as those whose pulmonary-artery pressure and pulmonary vascular resistance immediately fell by more than 20 percent after challenge) were treated for up to five years. Their survival was compared with that of the patients who did not respond and with patients enrolled in the National Institutes of Health (NIH) Registry on Primary Pulmonary Hypertension. Warfarin was given to 55 percent of the patients as concurrent therapy, on the basis of a lung scan showing nonuniformity of pulmonary blood flow (47 percent of patients who responded and 57 percent of those who did not respond). Results. Seventeen patients (26 percent) responded to treatment, as indicated by a 39 percen...
1,464 citations
TL;DR: In this paper, the authors proposed a joint fitting of heat flow and bathymetry with a model with a hotter, thinner oceanic lithosphere than in previous models, including those from older lithosphere previously treated as anomalous.
Abstract: Variations in sea-floor depth and heat flow with age provide the main constraints on the thermal structure and evolution of the oceanic lithosphere. Joint fitting of heat flow and bathymetry yields a model with a hotter, thinner lithosphere than in previous models. The new model provides a significantly better fit to the data, including those from older lithosphere previously treated as anomalous. This will facilitate the analysis of lithospheric processes, including the effects of mid-plate volcanism and swells, regional subsidence, and hydrothermal circulation near spreading centers.
1,379 citations
TL;DR: Though the 27 studies are far from perfect, it is believed that they confirm the importance of many well-accepted predictors and raise some questions about others, and encourages more investigations of the potentially different predictors of transitions to experimental or regular cigarette smoking.
Abstract: We review findings from 27 prospective studies of the onset of cigarette smoking conducted since 1980. Almost 300 measures of predictors of smoking onset were examined, and 74% of them provided multivariate support for predictors of onset derived from theory and previous empirical findings. Expected relationships were strongly supported for (a) socioeconomic status, with students with compromised status being more likely to try smoking; (b) social bonding variables, particularly peer and school bonding, with less support for family bonding; (c) social learning variables, especially peer smoking and approval, prevalence estimates, and offers/availability, with less consistent support for parent smoking and approval; (d) refusal skills self efficacy; (e) knowledge, attitudes and intentions, with the expected stronger predictions from intentions than from attitudes than from knowledge; and (f) broad indicators of self-esteem. The few investigators who analyzed their data separately by age, gender, or ethnicity found many differences by these factors, though there were too few of them to detect any pattern with confidence. Though the 27 studies are far from perfect, we believe that they confirm the importance of many well-accepted predictors and raise some questions about others. In particular, family smoking, bonding and approval each received unexpectedly low support. It is not clear whether this lack of support reflects reality as it has always been, is due to a changing reality, reflects developmental changes, either in the age of subjects or the stage of onset, or is due to poor measurement and too few tests. Future prospective studies need to be theory-driven, use measures of known reliability and validity, report analyses of scale properties, and use statistical methods appropriate to the hypotheses or theories under study. Finally, we encourage more investigations of the potentially different predictors of transitions to experimental or regular cigarette smoking. This will require multi-wave studies and careful measurement of changes in smoking behavior.
896 citations
TL;DR: It is shown that the volume of distribution and kinetic parameters of C-peptide distribution and metabolism vary by <30% in a population highly heterogenous in terms of age, sex, degree of obesity, and degree of glucose tolerance.
Abstract: Insulin secretion rates can be accurately estimated from plasma C-peptide levels with a two-compartment model for C-peptide distribution and degradation. In previous studies, the kinetic parameters of C-peptide clearance were derived in each subject from the decay curve observed after bolus intravenous injection of biosynthetic human C-peptide. To determine whether standard parameters for C-peptide clearance could be defined and used to calculate insulin secretion without obtaining a decay curve in each subject, we analyzed 200 decay curves of biosynthetic human C-peptide obtained in normal, obese, and non-insulindependent diabetes mellitus subjects studied in ourlaboratory. This analysis showed that the volume of distribution and kinetic parameters of C-peptide distribution and metabolism vary by
822 citations
TL;DR: It was found that those who had higher incomes had significantly higher quality of life scores on the social and economic subscale, and support for convergent validity was provided by a strong correlation between scores from the QLI and an assessment of life satisfaction.
Abstract: The purpose of this study was to examine the psychometric properties of the Quality of Life Index (QLI) (Ferrans & Powers, 1985a). The sample consisted of 349 patients selected randomly from the adult, in-unit hemodialysis patient population of Illinois. Factor analysis was used to examine the underlying factor structure. A four-factors solution best fit the data, indicating that there were four dimensions underlying the QLI: health and functioning, socioeconomic, psychological/spiritual, and family. Factor analysis of the four primary factors revealed one higher order factor, representing quality of life. Construct validity also was supported by the contrasted groups approach. As predicted, it was found that those who had higher incomes had significantly higher quality of life scores on the social and economic subscale. Support for convergent validity was provided by a strong correlation (r = .77) between scores from the QLI and an assessment of life satisfaction. Findings supported the internal consistency reliability of the entire QLI (alpha = .93) and the four subscales (alphas = .87, .82, .90, .77).
798 citations
TL;DR: Genetic analysis has yielded new generalizations about speciation and suggests promising avenues of research in this area of evolution.
Abstract: Called the "mystery of mysteries" by Darwin, speciation is still a little-understood area of evolution. Genetic analysis, however, has yielded new generalizations about speciation and suggests promising avenues of research.
771 citations
TL;DR: The authors derived a bi-factor item-response model for binary response data, where each item has a nonzero loading on the primary dimension and at most one of the s − 1 group factors.
Abstract: A plausibles-factor solution for many types of psychological and educational tests is one that exhibits a general factor ands − 1 group or method related factors. The bi-factor solution results from the constraint that each item has a nonzero loading on the primary dimension and at most one of thes − 1 group factors. This paper derives a bi-factor item-response model for binary response data. In marginal maximum likelihood estimation of item parameters, the bi-factor restriction leads to a major simplification of likelihood equations and (a) permits analysis of models with large numbers of group factors; (b) permits conditional dependence within identified subsets of items; and (c) provides more parsimonious factor solutions than an unrestricted full-information item factor analysis in some cases.
556 citations
TL;DR: The authors empirically examined the role of finances on college persistence by presenting a causal model that relied on several theoretical frameworks and found that financial aid is important not only because it equalizes opportunities between affluent and low-income students, but also because it facilitates the integration of the student into the academic and social components of the institution as well as by influencing his or her commitment to stay in college.
Abstract: The study empirically examined the role of finances on college persistence by presenting a causal model that relied on several theoretical frameworks. A quantitative model was tested via linear structural equations for categorical data that incorporated constructs from the financial aid literature as well as the persistence literature. The research design was longitudinal in nature and analyses were conducted on a sample of 466 college students who were attending a large public urban commuter institution in the spring of 1989. In sum, results appear to suggest that financial aid, and its concomitant attitude, is important not only because it equalizes opportunities between affluent and low-income students, but also because it facilitates the integration of the student into the academic and social components of the institution as well as by influencing his or her commitment to stay in college.
555 citations
TL;DR: This paper employed a panel data set consisting of annual observations on the 48 contiguous states from 1969 to 1983 to estimate input elasticity coefficients under a specification that allows for differences over time and across states.
537 citations
TL;DR: The biochemical properties and tissue distribution of GLUT5 are consistent with a physiological role for this protein as a fructose transporter.
TL;DR: For instance, the authors found that subjects with high ASI scores were five times more likely to have an anxiety disorder during the period 1984 to 1987, compared to subjects with low 1984 ASI score.
TL;DR: It is concluded that future research should focus on the part that gender-role explanations play in assigning meaning to caregiving behaviors and on the relatively small size of the effects found.
Abstract: This study applies meta-analysis techniques to the results of 14 descriptive studies of gender differences in caregiving to determine the size and significance of gender differences in caregiving stressors (level of elder impairment and level and type of task involvement) and in caregiver burden. There were essentially no significant gender differences in functional impairment of the frail care recipient, total caregiver involvement in care, or in money management tasks. Female caregivers were more likely to carry out personal care and household tasks and more likely to report greater burden. Given the relatively small size of the effects found, we conclude that future research should focus on the part that gender-role explanations play in assigning meaning to caregiving behaviors.
TL;DR: Regulation of chromosomally determined nutrient cation and anion uptake systems shows important similarities to regulation of plasmid-determined toxic ion resistance systems that mediate the outward transport of deleterious ions.
TL;DR: The details of the central nervous system's control over ingestive behavior were revealed and it was revealed that the licking behavior of rats is organized into bursts of licking at a high rate.
Abstract: The interlick interval distribution of rats while ingesting maltose under real and sham feeding conditions and while ingesting seven concentrations of sucrose under real feeding conditions was analyzed. The analysis revealed that the licking behavior of rats is organized into bursts of licking at a high rate. These bursts occurred in clusters that were separated by brief (250-500 ms) interruptions. The clusters were separated by intervals that ranged from 500 ms to many hundreds of seconds. Sham feeding increased the length of the meal by increasing the number but not the size of the clusters. Increasing the concentration of sucrose increased monotonically the size of the clusters but varied the number of clusters as an inverted-V-shaped function. This analysis revealed the details of the central nervous system's control over ingestive behavior.
TL;DR: It is shown that human peripheral blood lymphocytes (PBL) also express P-gp, and that P- GP expression correlates with the efflux of fluorescent dyes from PBL, and this efflux was suppressed not only by chemical inhibitors of P- gp but also by a P-GP-specific monoclonal antibody UIC2, thus providing direct evidence that it was mediated by P-gas.
TL;DR: In this article, the authors generalized the FDTD method to include the accurate modeling of curved surfaces and proposed the contour path method, which accurately models the illumination of bodies with curved surfaces, yet retains the ability to model corners and edges.
Abstract: The finite-difference-time-domain (FDTD) method is generalized to include the accurate modeling of curved surfaces. This generalization, the contour path CP), method, accurately models the illumination of bodies with curved surfaces, yet retains the ability to model corners and edges. CP modeling of two-dimensional electromagnetic wave scattering from objects of various shapes and compositions is presented. >
TL;DR: The results suggest that UIC2 or its derivatives provide an alternative or supplement to chemical agents for the reversal of MDR in clinical cancer.
Abstract: P-glycoprotein (Pgp), encoded by the MDR1 gene, is an active efflux pump for many structurally diverse lipophilic compounds. Cellular expression of Pgp results in multidrug resistance (MDR) in vitro and is believed to be a clinically relevant mechanism for tumor resistance to chemotherapy. We have developed a mouse monoclonal antibody, UIC2, that recognizes an extracellular epitope of human Pgp. UIC2 inhibited the efflux of Pgp substrates from MDR cells and significantly increased the cytotoxicity of Pgp-transported drugs, under the conditions where no effect was detectable with other anti-Pgp antibodies. Potentiation of cytotoxicity by UIC2 was observed with all the tested drugs associated with MDR (vinblastine, vincristine, colchicine, taxol, doxorubicin, etoposide, actinomycin D, puromycin, and gramicidin D) but not with any of the drugs to which MDR cells are not cross-resistant (methotrexate, 5-fluorouracil, cis-platinum, G418, and gentamicin). The inhibitory effect of UIC2 in vitro was as strong as that of verapamil (a widely used Pgp inhibitor) at its highest clinically achievable concentrations. Our results suggest that UIC2 or its derivatives provide an alternative or supplement to chemical agents for the reversal of MDR in clinical cancer.
TL;DR: Long-term administration of non-steroidal anti-inflammatory drugs can often be as effective as excision for the treatment of osteoid-osteoma, without the morbidity that is associated with the operation, especially in patients in whom operative treatment would be complex or might lead to disability.
Abstract: Twenty-four patients were evaluated and diagnosed, between August 1975 and July 1989, as having probable osteoid-osteoma. Fifteen patients had operative treatment (twelve immediate and three delayed); all fifteen had complete relief of pain. The remaining nine patients were treated with non-steroidal anti-inflammatory medications; all nine had complete relief of pain, and six had resolution of the symptoms without using non-steroidal anti-inflammatory drugs, after an average of thirty-three months (range, thirty to forty months) of treatment. Thus, long-term administration of non-steroidal anti-inflammatory drugs can often be as effective as excision for the treatment of osteoid-osteoma, without the morbidity that is associated with the operation, especially in patients in whom operative treatment would be complex or might lead to disability.
TL;DR: It is shown that human peripheral blood lymphocytes (PBL) also express P-gp, and that P- GP expression correlates with the efflux of fluorescent dyes from PBL, and this efflux was suppressed not only by chemical inhibitors of P- gp but also by a P-GP-specific monoclonal antibody UIC2, thus providing direct evidence that it was mediated by P-gas.
TL;DR: Considering the n‐3 fatty acids to be partial agonists relative to n‐6 fatty acids helps consolidate into a unified interpretation the many diverse reports and controversies on the actions of these two types of essential fatty acids.
Abstract: Considering the n-3 fatty acids to be partial agonists relative to n-6 fatty acids helps consolidate into a unified interpretation the many diverse reports and controversies on the actions of these two types of essential fatty acids Some research reports illustrate the similarities between these two types and some emphasize the differences, leaving readers to evaluate the status of n-3 fatty acids from a viewpoint that is conceptually similar to regarding a glass of water as half empty or half full Both n-3 and n-6 types of fatty acids must be obtained through the diet because they are not synthesized de novo by vertebrates Both types can support important physiological and developmental processes, can form eicosanoids (prostaglandins, leukotrienes, lipoxins, etc), can be esterified to and hydrolyzed from tissue glycerolipids, and can be metabolically elongated and desaturated to a variety of highly unsaturated fatty acids However, some nonesterified n-6 acids are vigorously converted to potent n-6 e
TL;DR: In this article, the combination sensitivity of single units in the hyperstriatum ventrale, pars caudale (HVc) of urethane-anesthetized zebra finches was studied.
Abstract: Song learning shapes the response properties of auditory neurons in the song system to become highly selective for the individual bird's own ("autogenous") song. The auditory representation of autogenous song is achieved in part by neurons that exhibit facilitated responses to combinations of components of song. To understand the circuits that underlie these complex properties, the combination sensitivity of single units in the hyperstriatum ventrale, pars caudale (HVc) of urethane-anesthetized zebra finches was studied. Some neurons exhibited nonlinear temporal summation, spectral summation, or both. The majority of these neurons exhibited low spontaneous rates and phasic responses. Most combination-sensitive neurons required highly accurate copies of sounds derived from the autogenous song and responded weakly to tone bursts, combinations of simple stimuli, or conspecific songs. Temporal combination-sensitive (TCS) neurons required either two or more segments of a single syllable, or two or more syllables of the autogenous song, to elicit a facilitated, excitatory response. TCS neurons integrated auditory input over periods ranging from 80 to 350 msec, although this represents a lower limit. Harmonic combination-sensitive (HCS) neurons required combinations of two harmonics with particular frequency and temporal characteristics that were similar to autogenous song syllables. Both TCS and HCS neurons responded much more weakly when the dynamical spectral features of the autogenous song or syllables were modified than when the dynamical amplitude (waveform) features of the songs were modified. These results suggest that understanding the temporal dynamics of auditory responses in HVc may provide insight into neuronal circuits modified by song learning.
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01 Jan 1992TL;DR: This paper discusses first-order theory - syntax first order theory - semantics logic programs - syntax Logic programs - semantics - models and interpretations substitutions and unifiers fixpoint theory, a comparison of definite and disjunctive logic programs and normal logic programs.
Abstract: Part 1 Introduction and background: motivation historical background. Part 2 Definitions and terminology: first-order theory - syntax first order theory - semantics logic programs - syntax logic programs - semantics - models and interpretations substitutions and unifiers fixpoint theory. Part 3 Declarative semantics: logical consequences model theory fixpoint theory comparison of definite and disjunctive logic programs. Part 4 Proof theory: query type and correct answers SLI resolution and SLD resolution soundness of SLI resolution completeness of SLI resolution computation rule comparison of SLD and SLI resolution. Part 5 Negation: generalized closed world assumption procedural interpretation for the GCWA non-herbrand models and the GCWA constructive answers. Part 6 Weak negation: weak generalized closed world assumption finite failure semantics fixpoint characterization completion theory procedural interpretation. Part 7 Normal logic programs: normal disjunctive logic programs the generalized disjunctive well-founded semantics stationary semantics comparison of semantics normal logic programs. Part 8 Proof theory - normal programs: SLIS resolution soundness of SLIS resolution completeness of SLIS resolution. Part 9 Disjunctive deductive databases: disjunctive deductive databases queries and answers incremental evaluation of hierarchical DDDB's model trees - a data structure for sets of minimal models incremental computation on model trees computing answers on trees meaningless models and denials. Part 10 Applications: view updates combining deductive databases.
TL;DR: A model is proposed for the line shape of the optical dielectric function of zinc-blende semiconductors and is found to be more generally valid than the harmonic-oscillator model, the critical-point (CP) model, or the model of Adachi.
Abstract: A model is proposed for the line shape of the optical dielectric function of zinc-blende semiconductors. For comparison with previously proposed models, this model is used primarily with spectroscopic ellipsometry data (but also transmission data below 1.5 eV) to obtain an analytic room-temperature dielectric function for GaAs. It is found to be more generally valid than the harmonic-oscillator model, the critical-point (CP) model, or the model of Adachi. It is applicable over the entire range of photon energies, below and above the lowest band gaps, incorporates the electronic band structure of the medium, and exactly satisfies the Kramers-Kronig transformation. It goes beyond the CP parabolic-band approximation in that it correctly takes into account the full analytic form of the electronic density of states and thus does not require the use of arbitrary cutoff energies. Also, it allows one to go beyond the usual approximation of Lorentzian broadening, which is known to be incorrect for elements and compounds above very low temperatures. For these reasons, it results in excellent quantitative agreement with experimental results for the dielectric function and for its derivatives with respect to photon energy, much better than that given by earlier models. Finally, the parameters of the model are physically significant and are easily determined as functions of composition for semiconductor alloys. Application of the model to the fitting of spectroscopic data on GaAs strongly suggests that spectroscopic ellipsometry does not measure the true bulk dielectric function. It also supports the conclusion that the line-shape broadening in GaAs at room temperature is more nearly Gaussian than Lorentzian.
TL;DR: The reproducibility of the results makes it likely that analysis of fatty-acid composition of plasma lipids from individuals will prove useful in estimating the diet-related tendency for severe thrombotic, arthritic or other disorders that are mediated by (n - 6) eicosanoids.
TL;DR: Clonidine was modestly effective in the short-term treatment of irritability and hyperactivity in some children with autistic disorder.
Abstract: Many autistic children have associated problems of inattention, impulsivity, and hyperactivity that limit the effectiveness of educational and behavioral interventions. Few controlled psychopharmacologic trials have been conducted in autistic children to determine which agents may be effective for these associated features. Eight male children (8.1 +/- 2.8 years) with autistic disorder, diagnosed by DSM-III-R criteria, completed a placebo-controlled, double-blind crossover trial of clonidine. Subjects were included in the study if they had inattention, impulsivity, and hyperactivity that was excessive for their developmental level. Subjects had not tolerated or responded to other psychopharmacologic treatments (neuroleptics, methylphenidate, or desipramine). Teacher ratings on the Aberrant Behavior Checklist irritability, stereotypy, hyperactivity, and inappropriate speech factors were lower during treatment with clonidine than during treatment with placebo. Attention deficit disorder with hyperactivity: Comprehensive Teacher's Rating Scale ratings were not significantly improved during the study, except for oppositional behavior. Parent Conners Abbreviated Parent-Teacher Questionnaire ratings significantly improved during clonidine treatment. Clonidine led to increased ratings of the side effects of drowsiness and decreased activity. Clinician ratings (Children's Psychiatric Rating Scale Autism, Hyperactivity, Anger and Speech Deviance factors; Children's Global Assessment Scale; Clinical Global Impressions efficacy) of videotaped sessions were not significantly different between clonidine and placebo. Clonidine was modestly effective in the short-term treatment of irritability and hyperactivity in some children with autistic disorder.
TL;DR: Several non-invasive microwave techniques for contact and remote sensing of circulatory and respiratory movements and volume changes have been developed, capable of registering instantaneous changes in fluid volume, pressure pulse, heart rate, and respiration rate in contact with body surface or at distances greater than 30 m.
Abstract: The ability non-invasively to detect and monitor the movement of tissues and organs from outside the body provides many worthwhile areas of potential biomedical applications. Several non-invasive microwave techniques for contact and remote sensing of circulatory and respiratory movements and volume changes have been developed. In general, these systems consist of a microwave generator, a sampling device, a transmitting-receiving antenna, a set of signal-conditioning and processing devices, and a display unit. They operate at continuous-wave frequencies between 1 and 35 GHz and make use of amplitude and phase information derived from the received signal. The average power density of energy radiated by present systems ranges from approximately 0.001–1.0 mW/cm2. These systems are capable of registering instantaneous changes in fluid volume, pressure pulse, heart rate, and respiration rate in contact with body surface or at distances greater than 30 m, or behind thick layers of non-conductive walls. 1992 Wiley-Liss, Inc.
TL;DR: A constitutive viral promoter is identified which is active throughout stratified epithelium as well as a novel promoter which is induced upon epithelial cell differentiation in an in vitro organotypic raft culture system which allows for epithelial stratification at the air-liquid interface.
Abstract: The expression of viral genes during the productive life cycle of human papillomaviruses (HPV) is tightly coupled to the differentiation program of epithelial cells. We have examined transcription of HPV as a function of differentiation in an in vitro organotypic raft culture system which allows for epithelial stratification at the air-liquid interface. When CIN612 cells, which contain episomal copies of HPV type 31b (HPV31b), were allowed to stratify in raft cultures, they differentiated in a manner which was histologically similar to that seen in a cervical intraepithelial neoplasia I biopsy lesion. In monolayer cultures of CIN612 cells, two major polycistronic HPV31b transcripts of 1.7 kb which encode (i) E6, E7, E1-E4, and E5 and (ii) E6*, E7, E1-E4, and E5 were identified. These RNAs initiated at a promoter, P97, in the upstream regulatory region of the virus. Following differentiation in raft cultures, the relative abundance of RNAs initiated at P97 was unchanged. In contrast, the expression of a 1.3-kb RNA encoding an E1-E4 fusion protein and E5 was found to increase substantially following differentiation. This transcript was initiated at a novel promoter within the E7 gene (P742). These studies have therefore identified a constitutive viral promoter which is active throughout stratified epithelium as well as a novel promoter which is induced upon epithelial cell differentiation.
TL;DR: The afferent connections of the pedunculopontine tegmental nucleus (PPT) and the adjacent midbrain extrapyramidal area (MEA) were examined by retrograde tracing with wheat germ agglutinin‐conjugated horseradish peroxidase (WGA‐HRP).
Abstract: The afferent connections of the pedunculopontine tegmental nucleus (PPT) and the adjacent midbrain extrapyramidal area (MEA) were examined by retrograde tracing with wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP). Major afferents to the PPT originate in the periaqueductal gray, central tegmental field, lateral hypothalamic area, dorsal raphe nucleus, superior colliculus, and pontine and medullary reticular fields. Other putative inputs originate in the paraventricular and preoptic hypothalamic nuclei, the zona incerta, nucleus of the solitary tract, central superior raphe nucleus, substantia innominata, posterior hypothalamic area, and thalamic parafascicular nucleus. The major afferent to the medially adjacent MEA originates in the lateral habenula, while other putative afferents include the perifornical and lateral hypothalamic area, periaqueductal gray, superior colliculus, pontine reticular formation, and dorsal raphe nucleus. MEA inputs from basal ganglia nuclei include moderate projections from the substantia nigra pars reticulata, entopeduncular nucleus, and a small projection from the globus pallidus, but not the subthalamic nucleus. Dense anterograde labeling was observed in the substantia nigra pars compacta, entopeduncular nucleus, subthalamic nucleus, globus pallidus, and caudate-putamen only following WGA-HRP injections involving the MEA. The results of this study demonstrate that the PPT and MEA share many potential afferents. Remarkable differences were found that support distinguishing between these two nuclei in future studies regarding the functional organization of the midbrain and pons. The results, for example, confirm our previous observations that the largely reciprocal connections between the midbrain and basal ganglia distinguish the MEA from the PPT. Afferents from the lateral habenula and contralateral superior colliculus represent extensions of more traditional basal ganglion circuitry which further delineate the MEA from the PPT. The results are discussed with respect to the important role of the midbrain and pons in behavioral state control and locomotor mechanisms.
TL;DR: The instability of poly(GT) and poly(G) tracts in the yeast Saccharomyces cerevisiae was found to be dramatically unstable, altering length at a minimal rate of 10(-4) events per division.
Abstract: All eukaryotic genomes thus far examined contain simple sequence repeats. A particularly common simple sequence in many organisms (including humans) consists of tracts of alternating GT residues on one strand. Allelic poly(GT) tracts are often of different lengths in different individuals, indicating that they are likely to be unstable. We examined the instability of poly(GT) and poly(G) tracts in the yeast Saccharomyces cerevisiae. We found that these tracts were dramatically unstable, altering length at a minimal rate of 10(-4) events per division. Most of the changes involved one or two repeat unit additions or deletions, although one alteration involved an interaction with the yeast telomeres.