Three downstream sites repress transcription of a Ty2 retrotransposon in Saccharomyces cerevisiae

Transcription of Ty1 and Ty2 retrotransposons of the yeast Saccharomyces cerevisiae is modulated by multiple downstream regulatory sites. Both transposon families include a positively acting site within the transcribed region which resembles a higher eukaryotic enhancer. We have demonstrated the existence of a repression site distal to the enhancer of the Ty2-917 element. Here we describe experiments investigating the internal structure of this site. We show that this 200-bp region includes three distinct repression sites which we term DRSI (downstream repression site I), DRSII, and DRSIII. Individually each site causes almost twofold repression, and together the sites repress eightfold. Unexpectedly, when the entire region encompassing the DRS sites is moved outside the transcription unit, it acts as a qualitatively positively acting element. In this context the DRS sites still repress transcription, since eliminating them increases transcription further. That the region can activate transcription implies that it includes activation sites in addition to the three repression sites. The change from qualitatively negatively acting to positively acting must reflect a change in the relative effects of the multiple positive and negative sites; when moved outside the transcription unit, the activators predominate. Importantly, DRSII and DRSIII repress transcription autonomously when inserted upstream of a heterologous promoter activated by the transcriptional activator GCN4, showing that they are indeed transcriptional repression sites.

Altered brain development in Turner's syndrome: an event-related potential study

We compared event-related brain potentials (ERPs) and reaction time (RT) measures from untreated young (prepubertal and peripubertal; ages 9 to 14) and old (postpubertal; ages 15 to 20) Turner's syndrome (TS) subjects with those from normal age-matched controls. Comparisons among groups permitted the assessment of the relative roles of congenital and maturational brain alterations as possible bases of the cognitive deficits in TS. All subjects were presented with series of auditory stimuli, and they either counted one of the two stimuli or made rapid discriminative button presses to both. The results indicated that, whereas the ERPs in young TS females were essentially the same as those in their age-matched controls, the ERPs in old TS females more closely resembled those in both young groups than those in their age-matched controls. Specifically, a late (400 to 900 msec) frontal negative slow wave (Nc) in the old TS subjects failed to show the normal maturational course in which the amplitude and duration of this component steadily decreases with age. Except for slightly greater amounts of N1 amplitude in the young TS group, the latencies, amplitudes, and scalp distributions of the other ERP components (N1, P2, N2, P300) were all the same at all ages in the TS subjects and their controls. Behaviorally, both TS groups had longer RTs than their controls but, consistent with the ERP results, they did not make more errors.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of physical health benefits utilization. Mental and physical health claimants, 1989 and 1990

Research has indicated an association between mental health problems and physical illness, including higher physical health benefits utilization among persons with a mental health diagnosis. We hypothesized that mental health claimants will have higher covered health benefits and be more likely to make physical health claims than physical health claimants. The data for the study included all health benefits claims for 1989 and 1990. The results indicated that mental health claimants have higher total covered benefits and higher covered benefits in a number of diagnostic categories. In addition, the findings revealed a greater likelihood to make any health claim as well as a claim for several diagnostic categories among persons with a mental health diagnosis. The study indicates the need for coordination between mental health and physical health benefits cost management.

Growth pressure can drive early chick lens geometries

Over a number of morphological stages during chick lens morphogenesis, a flat plate of cuboidal ectodermal cells infolds to form a deep cup of tall, pyramidal lenticular cells. This invagination process is accompanied by asynchronous cellular multiplication over a basal region constrained by an adhesive extracellular matrix. A lens placode is formed as the cells crowd into columnar "palisades." A lens cup forms as the cells pyramidalize owing to basal nuclear movements. Invagination ends when the opening into the lens cup is closed to form a lens vesicle. In this paper, equations are developed that provide a quantitative, mathematical formulation of an earlier theory that explains this invagination as a growth driven process. The equations take into account the lens cell cycle, the extracellular matrix, and nuclear migratory behaviors. Based on the equations, geometries simulating the morphological stages and the cell cycle phases are generated for the 1st day of lens development. The mathematical formulation of lens invagination helps demonstrate how growth pressure alone can be the primary driving force for tissue folding. In this view, recruitment occurs before the shape changes; and cell-autonomous mechanisms of invagination, involving the cytoskeleton or differential adhesion alone, offer inadequate explanations of these changes.

CAR2, a prestalk cAMP receptor required for normal tip formation and late development of Dictyostelium discoideum

Extracellular cAMP serves as a primary signaling molecule to regulate the development of Dictyostelium discoideum. It is required for chemotaxis, aggregation, cytodifferentiation, and morphogenetic movement. The receptors for cAMP are members of the family of cell-surface receptors that are linked to G proteins and characterized by seven putative transmembrane domains. Previously, we have isolated the gene for the cAMP receptor subtype 1 (CAR1) from Dictyostelium and suggested that several genes related to CAR1 were present in the genome. Here, we describe a family of cAMP receptor genes of Dictyostelium and the isolation and function of the gene for the cAMP receptor subtype 2, CAR2. CAR2 is structurally similar to CAR1. Overall, their transmembrane and loop domains are approximately 75% identical in amino acid sequence; however, their carboxyl termini are quite dissimilar; CAR2 possesses homopolymeric runs of histidines and asparagines that are absent from the corresponding region in CAR1. Although CAR1 is maximally expressed during the early stages of development, CAR2 is expressed only after cells have aggregated and, then, preferentially in prestalk cells. Transgenic Dictyostelium that have had their wild-type CAR2 gene replaced by a defective copy using homologous recombination proceed through early development but are detained at the tight mound stage. CAR2 may be required for cAMP-directed sorting of prestalk cells during pattern formation within the aggregation mound. Furthermore, although prestalk genes are expressed normally in aggregates that lack CAR2, they exhibit an enhanced expression of prespore-specific mRNA. Previously, we had shown that there was a requirement for CAR1 during early development. The present results demonstrate that the multiple responses of Dictyostelium to cAMP are regulated by distinct cAMP receptors that are encoded by unique genes.

Five to eight year results of the Johnson-Elloy (Accord) total knee arthroplasty

Between February 1982 and December 1985, 133 knees in 107 patients were replaced with a cemented Johnson-Elloy (Accord) total knee arthroplasty. Thirty-five knees were lost during the follow-up period because of death in 29, revision in 3, infection in 1, and refusal of follow-up evaluation in 2. The results of the remaining 98 knees in 76 patients with a 5-8 year follow-up period are presented. The procedure was carried out in all cases presenting for surgery, irrespective of pathology and degree of deformity. The range of flexion achieved as a mean of 93.5 degrees in the osteoarthritic group and 100 degrees in the rheumatoid arthritic group. Eighty-seven percent of the osteoarthritic group and 95% of the rheumatoid arthritic group achieved between 10 degrees and 50 degrees of rotation at 90 degrees of flexion, which was maintained for the duration of the study. Adequate stability in both groups, valgus-varus and rotation in extension, and anteroposterior in flexion was achieved. Survivorship was 97.7% at 80 months.

Relationship of C5a receptor modulation to the functional responsiveness of human polymorphonuclear leukocytes to C5a

The relationship of C5a receptor expression on human polymorphonuclear leukocytes (PMN) to the functional response of these cells to C5a was studied using flow cytometry. C5a receptor expression was determined with a fluorescein conjugate of C5a and oxidative burst activity was monitored by conversion of dichlorofluorescein to dichlorofluorescein (DCF) as a measure of H2O2 production. These studies showed that after incubation of PMN with increasing concentrations of C5a, and allowing for internalization of bound ligand, more than 40% of the cell surface C5a receptors were internalized before the DCF response to optimal concentrations of C5a was decreased below the levels for untreated control cells. Although C5a responsiveness was lost after preincubation with 10(-8) M C5a, cells remained responsive to formyl peptide. In other studies, cells were preincubated with unlabeled C5a under conditions that provided for internalization of nearly all C5a receptors. PMN were then cultured for up to 90 min and monitored for C5a receptor reexpression and return of cell function. In these studies, the DCF response of PMN to C5a returned to 100% much earlier than the cells regained full expression of C5a receptors. The DCF response to formyl peptide remained intact throughout the period of C5a receptor reexpression. These studies showed that once > 40% of the original population of C5a receptors are reexpressed on the PMN, that these cells regain 100% of their functional responsiveness to C5a in the DCF assay. Evaluation of the affinity and number of C5a receptors using 125I-labeled C5a after receptor reexpression showed that maximal receptor reexpression was approximately 73% of that obtained with control cells and the Kd of reexpressed receptors was 0.60 vs 0.94 nM for control cells. These studies demonstrate that only a portion of the total C5a receptors expressed on PMN are essential to stimulate a 100% functional response in PMN and that the reexpressed receptors are capable of transducing a signal that activates the oxidative burst in these cells.

Does depression invalidate competence? Consultants' ethical, psychiatric, and legal considerations

The ethical principle of respect for autonomy has come into its own In American medicine since World War II as equal in importance to the traditional medicomoral principles of nonmaleficence and beneficence. Respect for autonomy provides the ethical underpinning for the patient's right to exercise an informed choice – whether to consent to or to refuse recommended medical treatment. However, an informed choice demands a certain level of competence. Typical criteria for patient competence to accept or to refuse medical treatments Include ability to make a choice and ability to comprehend the nature of the treatment, as well as the risks and benefits of accepting or refusing the treatment.

An in vitro dynamic evaluation of prophylactic knee braces during lateral impact loading

To determine the ability of prophylactic knee braces to reduce or limit medial collateral and anterior cruciate ligament elongation under dynamic loading conditions, we used cadaveric specimens that had a surrogate soft tissue material that matched the tissue compliance of in vivo contracted muscles. Eight cadaveric specimens were fitted with four prophylactic knee braces and instrumented with Hall Effect Strain Transducers on both the medial collateral and anterior cruciate ligament. Each specimen was mounted in a testing frame while a lateral impact was applied to the knee joint by a pendulum at levels below the injury threshold. Legs were tested at 0 degrees and 30 degrees of knee flexion, both with and without an intact anterior cruciate ligament. The maximum elongation for each ligament was calculated as a percentage of the initial measured length. The addition of a prophylactic knee brace significantly reduced the level of impact force at the point of impact, but this did not result in a significant reduction of anterior cruciate ligament elongation for any test. Although not significant, all braces tested were more effective at reducing medial collateral ligament elongation during a lateral impact with the knee flexion at 30 degrees than at 0 degrees.

F reticulocyte response in sickle cell anemia treated with recombinant human erythropoietin: a double-blind study

Studies on baboons and preliminary observations in three patients with sickle cell anemia (SS) suggested that high doses of pulse administered recombinant human erythropoietin (rHuEPO) stimulate F-reticulocyte production. We now report on the administration of rHuEPO in a double-blind format to ascertain frequency of response and potential precipitation of side effects. Ten patients were enrolled, but one was discontinued due to the indication of a blood transfusion. Of the other nine, five received rHuEPO in escalating doses (from 400 to 1,500 U per kg twice daily [BID] per week), alternating with a placebo, in blinded fashion. The second group, consisting of four patients, followed an identical protocol (except starting dose was 1,000 U/Kg, BID per week) and were iron supplemented during treatment. The criterion of response was a transient doubling (as a minimum) of the steady-state F-reticulocyte level. We found that none of the five patients in the first group responded to rHuEPO, and two of them became iron deficient, as judged by a significant decrease in ferritin. Of the second group, four patients responded with F-reticulocyte increases. In three patients, open label administration of rHuEPO confirmed the effect. We observed seven painful episodes during this study, two during the EPO administration and five during the placebo arm. Three patients were phlebotomized because the hemoglobin level increased 1.5 g/dL more than steady-state levels. Of the six patients followed-up by percent dense cell determinations, one exhibited increased levels during periods of the treatment, whereas the other five showed no change. No anti-rHuEPO antibodies were detected. We conclude that rHuEPO can stimulate F-reticulocyte response in some patients with sickle cell anemia, without apparent negative clinical side effects. The state of iron stores may be critical. Whether higher doses of rHuEPO and/or a different regimen might induce sustained F cells and fetal hemoglobin increases remains to be determined.

Determination of plasma and brain concentrations of SCH 39166 and their correlation to conditioned avoidance behavior in rats

Plasma and brain concentrations of the dopamine D1 receptor antagonist, SCH 39166, were measured and compared to behavioral activity in the conditioned avoidance response paradigm (CAR). SCH 39166 was administered at two behaviorally active doses (1 mg/kg, SC and 10 mg/kg, PO) and the time course for CAR activity was compared with the plasma and brain concentrations of unconjugated SCH 39166. Conjugation and N-demethylation of SCH 39166 after oral administration were also determined and first pass metabolism examined. Results from these studies demonstrated a similar time-dependent disappearance of unconjugated SCH 39166 from both the plasma and brain, independent of route of administration. Brain concentrations of SCH 39166 were approximately 5-fold higher than corresponding plasma concentrations, regardless of route. However, plasma and brain concentrations of unconjugated SCH 39166 were higher after SC administration of 1.0 mg/kg, than after PO administration of 10 mg/kg, suggesting a substantial first pass metabolism of SCH 39166. In addition, total (conjugated and unconjugated) plasma concentrations of SCH 39166 were at least 10-fold higher than unconjugated concentrations of SCH 39166 after PO administration of 10 mg/kg, demonstrating that a high proportion of drug was conjugated. Metabolism to the N-desmethyl analog, SCH 40853, was observed after PO administration of 10 mg/kg SCH 39166 and a high proportion of conjugation of the desmethyl analog was also seen. Finally, plasma concentrations of unconjugated SCH 39166 exhibited a high positive correlation (r = 0.934, P < 0.001) with brain concentrations of unconjugated SCH 39166.(ABSTRACT TRUNCATED AT 250 WORDS)

On the neural generators of the P300 component of the event-related potential

The triarchic model of P300 amplitude (Johnson, 1986, 1988a) postulated that the overall amplitude of the P300 recorded at any given electrode site represented the summation of activity from different neural generators, each related to the processing of a different type of information. However, neither of these original accounts provided an explicit description of the methods required to establish experimentally the presence of multiple neural sources. This paper reviews the triarchic amplitude model, the subsequently obtained data that support the postulated presence of multiple generators underlying the P300, and the methods used to demonstrate the presence of these multiple sources. These methods are straightforward because it is only necessary to show that the portions of P300 amplitude associated with different experimental variables have different scalp distributions. The implications of the multiple-generator basis of P300 on such factors as component definition, neural source analyses, and the cognitive processes underlying its activity are discussed.

Relationship of C5a receptor modulation to the functional responsiveness of human polymorphonuclear leukocytes to C5a

The relationship of C5a receptor expression on human polymorphonuclear leukocytes (PMN) to the functional response of these cells to C5a was studied using flow cytometry. C5a receptor expression was determined with a fluorescein conjugate of C5a and oxidative burst activity was monitored by conversion of dichlorofluorescein to dichlorofluorescein (DCF) as a measure of H2O2 production. These studies showed that after incubation of PMN with increasing concentrations of C5a, and allowing for internalization of bound ligand, more than 40% of the cell surface C5a receptors were internalized before the DCF response to optimal concentrations of C5a was decreased below the levels for untreated control cells. Although C5a responsiveness was lost after preincubation with 10(-8) M C5a, cells remained responsive to formyl peptide. In other studies, cells were preincubated with unlabeled C5a under conditions that provided for internalization of nearly all C5a receptors. PMN were then cultured for up to 90 min and monitored for C5a receptor reexpression and return of cell function. In these studies, the DCF response of PMN to C5a returned to 100% much earlier than the cells regained full expression of C5a receptors. The DCF response to formyl peptide remained intact throughout the period of C5a receptor reexpression. These studies showed that once &gt; 40% of the original population of C5a receptors are reexpressed on the PMN, that these cells regain 100% of their functional responsiveness to C5a in the DCF assay. Evaluation of the affinity and number of C5a receptors using 125I-labeled C5a after receptor reexpression showed that maximal receptor reexpression was approximately 73% of that obtained with control cells and the Kd of reexpressed receptors was 0.60 vs 0.94 nM for control cells. These studies demonstrate that only a portion of the total C5a receptors expressed on PMN are essential to stimulate a 100% functional response in PMN and that the reexpressed receptors are capable of transducing a signal that activates the oxidative burst in these cells.

Effects of brief, heavy exertion on circulating lymphocyte subpopulations and proliferative response

Ten healthy males (mean age 22.3 +/- 0.8 yr) pedaled with maximal effort for 30 s against a workload adjusted prior to the start of the test to 0.98 N.kg body mass-1. Blood samples were collected before, and 3 min and 1 h following exercise. Peak and average power mean values were 1020 +/- 51 and 738 +/- 34 W, respectively. Total leukocytes increased 40% in response to the exercise bout, but were 16% below pretest levels after 1 h of recovery (F = 123, P < 0.001). Neutrophils and lymphocytes represented approximately 60% and 30% of the leukocytosis, respectively. Lymphocytes increased 30% following exercise, but were 36% below pretest levels after 1 h recovery (F = 56.4, P < 0.001). The post-test lymphocytosis can be explained primarily from the 176% increase in natural killer cells (NK) and 28% increase in cytotoxic/suppressor T cells, while the 1-h recovery lymphopenia occurred because of a sharp decrease in total T cells and a moderate decrease in NK cells. No significant changes in lymphocyte proliferative response or serum immunoglobulin levels were found when appropriate adjustments for changes in plasma volume or lymphocyte subset changes were made. Plasma epinephrine increased 300% in response to the exercise bout, and best explains the measured changes in circulating levels of lymphocyte subsets. These results demonstrate that changes in circulating levels of leukocyte and lymphocyte subsets, especially NK cells, occur rapidly in response to 30 s of brief, heavy exertion.