Steroidogenic factor 1 and Dax-1 colocalize in multiple cell lineages: potential links in endocrine development

Mutations of the orphan nuclear receptors, steroidogenic factor 1 (SF-1) and DAX-1, cause complex endocrine phenotypes that include impaired adrenal development and hypogonadotrophic hypogonadism. These similar phenotypes suggest that SF-1 and DAX-1 act in the same pathway(s) of endocrine development. To explore this model, we now compare directly their sites of expression. In mouse embryos, SF-1 expression in the urogenital ridge and brain either preceded or coincided with Dax-1 expression, with coordinate expression thereafter in the adrenal cortex, testis, ovary, hypothalamus, and anterior pituitary. The striking colocalization of SF-1 and Dax-1 supports the model that they are intimately linked in a common pathway of endocrine development. The slightly earlier onset of SF-1 expression and its ability to bind specifically to a conserved sequence in the Dax-1 5'-flanking region suggested that SF-1 may activate Dax-1 expression. However, promoter activity of Dax-1 5'-flanking sequences did not require this potential SF-1-responsive element, and Dax-1 expression was unimpaired in knockout mice lacking SF-1, establishing that SF-1 is not required for Dax-1 gene expression in these settings. Although the precise mechanisms remain to be established and may be multifactorial, our results strongly suggest that these two orphan nuclear receptors interact in a common pathway of endocrine development.

Social loafing and identifiability: the mediating role of achievement goal orientations

The purpose of this investigation was to determine if differences in the tendency to exhibit social loafing is a function of achievement-goal orientation and identifiability. Ninety-six males drawn from 10th-grade physical education classes responded to the Task and Ego Orientation in Sport Questionnaire (Duda, 1992) prior to completing a 30-meter sprint task under three separate conditions: as an individual, in a team with individual performance identified, and in a team with individual performance not identified. Following a median split of the task and ego values reported, subjects were divided into high and low groups for both orientations. Sprint times were compared by means of a 2 x 2 x 3 ANOVA (task x ego x sprint condition) with repeated measures on the third factor. Findings revealed that individuals with a combined low task/high ego orientation were significantly slower in the nonidentifiable team condition than in the other two conditions, whereas high-task/low-ego-oriented individuals demonstrated consistent performance across all three conditions. While confirming that identifiability of performance is an important situational variable, the findings suggest that the dispositional factor of achievement orientation may interact to provide a more detailed explanation of the social loafing phenomenon.

Sox9 expression during gonadal development implies a conserved role for the gene in testis differentiation in mammals and birds

Heterozygous mutations in SOX9 lead to a human dwarfism syndrome, Campomelic dysplasia. Consistent with a role in sex determination, we find that Sox9 expression closely follows differentiation of Sertoli cells in the mouse testis, in experimental sex reversal when fetal ovaries are grafted to adult kidneys and in the chick where there is no evidence for a Sry gene. Our results imply that Sox9 plays an essential role in sex determination, possibly immediately downstream of Sry in mammals, and that it functions as a critical Sertoli cell differentiation factor, perhaps in all vertebrates.

Mouse Dax1 expression is consistent with a role in sex determination as well as in adrenal and hypothalamus function

Duplications of a chromosome Xp21 locus DSS (Dosage Sensitive Sex reversal) are associated with male to female sex reversal. An unusual member of the nuclear hormone receptor superfamily, DAX1, maps to the DSS critical region and is responsible for X-linked adrenal hypoplasia congenita. Here we describe the isolation of the mouse Dax1 gene and its pattern of expression during development. Expression was detected in the first stages of gonadal and adrenal differentiation and in the developing hypothalamus. Moreover, Dax1 expression is down-regulated coincident with overt differentiation in the testis, but persists in the developing ovary. Comparison of the predicted protein products of the human and mouse genes show that specific domains are evolving rapidly. Our results suggest a basis for adrenal insufficiency and hypogonadotropic hypogonadism in males affected by adrenal hypoplasia congenita and are consistent with a role for DAX1 in gonadal sex determination.

Reproducibility of blood pressure and heart rate reactivity: a meta-analysis

Reproducibilities of blood pressure and heart rate (HR) reactivity reported in studies assessing responses to the same laboratory stressors across occasions were reviewed with meta-analytic techniques. Changes in HR had the greatest reproducibility (r = .555), followed by systolic blood pressure (SBP) (.407) and diastolic blood pressure (DBP) (.348). Both SBP and HR response reproducibility was higher at shorter test-retest intervals, whereas DBP values varied unsystematically with length of test-retest interval. Older samples exhibited higher SBP and DBP reproducibility to stressors. SBP and DBP reproducibilities were better for tasks that did not make speech demands. The reliability of reactivity assessment was higher when based on three or more measurements. On the basis of available evidence, the drop in stress reproducibility, as test-retest interval increases, places limits on the viability of BP reactivity as a strong marker or risk factor for coronary heart disease.

Effects of goal-setting interventions on selected basketball skills: a single-subject design

The purpose of this investigation was to examine the effects of a goal-setting intervention program on selected components of basketball performance over the course of a competitive season. A multiple-baseline, single-subject design was used with baseline observations on various performance components (e.g., turnovers, rebounds), collected for four elite college basketball players during their first eight games of the season. At the midseason break, these players selected one aspect of their play that they felt would benefit from improvement. A goal-setting program was designed based on the goal attainment scaling procedure recommended by Smith (1988), whereby subjects generated numerical targets for their chosen components. Performance components were then assessed for the next eight games as they had been in the preintervention phase. Following the intervention, 3 of the 4 subjects showed consistent improvements in their targeted areas of performance. Also, there were no outcome changes in the performance components that weren't targeted by the subjects. The findings suggest that future studies may benefit from achieving greater ecological validity and utilizing alternative designs to the traditional nomothetic approaches which may tend to mask positive intervention effects on certain individuals.

Intensity and frequency dimensions of competitive state anxiety

This study reports a preliminary investigation of intensity and frequency of symptoms of competitive state anxiety. Forty-nine track and field athletes (27 males, 22 females) responded to a modified version of the Competitive State Anxiety Inventory-2 (CSAI-2) on four occasions during the period leading up to an important competition: 2 days, 1 day, 2 h and within 30 min of competing. The questionnaire included the existing CSAI-2 (intensity) scale as well as a frequency scale for each of the 27 items of the CSAI-2. The intensity and frequency dimensions of each of the CSAI-2-sub-scales were then compared between the four conditions by means of two-way analyses of variance (gender x time-to-competition). In the case of cognitive anxiety, time-to-event effects were observed for intensity and frequency for both males and females. The intensity of the response was significantly greater at the final stage of testing than it was 2 days before competition, while the frequency of the response increased progressively throughout the experimental period. This dissociative patterning for the cognitive anxiety dimensions is discussed in the light of Multidimensional Anxiety Theory predictions. For somatic anxiety, the time-to-event effects that emerged for intensity and frequency revealed that both values increased progressively as the time to compete neared, for both male and females. The results for self-confidence revealed no effects for intensity or frequency for either gender. The findings from structured follow-up interviews served to corroborate these quantitative findings by providing information that supported the conclusions drawn from the questionnaire data. In particular, the athletes reported that they experienced considerable increases in the frequency of intrusive anxiety cognitions. While these findings clearly need to be substantiated, they do provide evidence of the existence of an additional dimension of anxiety that may assist our understanding of this complex concept. The measurement of competitive state anxiety may benefit from this more detailed approach as opposed to the rather limited intensity-alone perspective.

Intensity and direction dimensions of competitive state anxiety and relationships with performance

This study examined relationships between intensity and direction dimensions of competitive state anxiety, and also relationships with beam performance in a sample of female gymnasts. The 48 gymnasts, whose ages ranged from 14 to 16 years, competed in a beam competition and were divided, via the median split technique, into poor performance and good performance groups. All the subjects completed a modified version of the Competitive State Anxiety Inventory-2 (CSAI-2) 10 min prior to performance. This inventory included the original intensity scale plus a direction scale in which subjects rated the degree to which the experienced intensity of each symptom was either facilitative of debilitative to subsequent beam performance. Analyses of variance showed no significant group differences on any of the CSAI-2 sub-component intensity scores, or on somatic anxiety and self-confidence direction scores. However, the good performance group reported their cognitive anxiety intensity as being more facilitating and less debilitating to performance than the poor performance group. Stepwise multiple-regression analyses showed that the only significant predictor of beam performance was self-confidence intensity. These findings support the proposal that sports performers' directional perceptions of their anxiety symptoms may provide further understanding of the competitive state anxiety response, and also emphasize the importance of self-confidence in predicting performance.

Influence of sequences in the long terminal repeat and flanking cell DNA on polyadenylation of retroviral transcripts

Readthrough transcripts are formed during retrovirus infection by polyadenylation of viral RNA in cellular sequences adjacent to the provirus. We have studied such transcripts in avian leukosis virus-infected cell clones containing a single provirus, either the wild type or one with an inactivating mutation in the poly(A) addition signal. All individual wild-type proviruses produced readthrough transcripts, implying that this property is not restricted to a few integration sites. The range of sizes of viral RNA in the mutant lacking a correct signal for poly(A) addition reflected both the occurrence of functional polyadenylation sites within flanking cell DNA and increased usage of cryptic sites within viral sequences.

Circular transcripts of the testis-determining gene Sry in adult mouse testis

Sry is expressed at higher levels in the adult testis, where no function has been determined, than in the genital ridge, its critical site of action. cDNA and 5' RACE clones isolated from testis or from Sry-transfected cell lines have an unusual structure, with 3' sequences located in a 5' position. RNAase protection assays and reverse transcription polymerase chain reactions confirmed that these unusual RNA molecules represent the most abundant transcript in testis. Furthermore, oligonucleotide hybridization and RNAase H digestion proved that these Sry RNA molecules are circular. Similar transcripts were detected in the testes of mice with Mus musculus musculus, Mus musculus domesticus, and Mus spretus Sry genes. The circular RNA is found in the cytoplasm but is not substantially bound to polysomes. We suggest that the circles arise from normal splicing processes as a consequence of the unusual genomic structure surrounding the Sry locus in the mouse.

Intensity and direction as dimensions of competitive state anxiety and relationships with competitiveness

This study examined differences in intensity and direction of symptoms of competitive state anxiety in high and low competitive subjects from the sports of rugby union, basketball, soccer, and field hockey. The 69 men were dichotomized via a median-split into high and low competitive groups based on their scores on the Sport Orientation Questionnaire. All subjects completed a modified version of the Competitive State Anxiety Inventory-2 30 minutes prior to competition. This inventory included the original intensity scale plus a direction scale on which subjects rated the extent the experienced intensity of each symptom was either facilitative or debilitative to subsequent performance. There were no significant group differences on intensity of cognitive anxiety or of somatic anxiety or on direction of somatic anxiety; however, the highly competitive group of 34 subjects reported their anxiety as more facilitative and less debilitative than the low competitive group (n = 35). This supports the proposal that sports performers' directional perceptions of their anxiety symptoms may provide further understanding of the competitive state-anxiety response.

Mechanism of transduction by retroviruses

Retroviruses can capture cellular sequences and express them as oncogenes. Capture has been proposed to be a consequence of the inefficiency of polyadenylation of the viral genome that allows the packaging of cellular sequences flanking the integrated provirus in virions; after transfer into virions, these sequences could be incorporated into the viral genome by illegitimate recombination during reverse transcription. As a test for this hypothesis, a tissue culture system was developed that mimics the transduction process and allows the analysis and quantitation of capture events in a single step. In this model, transduction of sequences adjacent to a provirus depends on the formation of readthrough transcripts and their transmission in virions and leads to various recombinant structures whose formation is independent of sequence similarity at the crossover site. Thus, all events in the transduction process can be attributed to the action of reverse transcriptase on readthrough transcripts without involving deletions of cellular DNA.

Physical characterisation of plasmids in a morpholine-degrading mycobacterium

The plasmid content of an environmental mycobacterium (MorG) which degrades morpholine (Mor+ phenotype) was investigated. The combination, in what appears to be a novel way, of restriction endonuclease digestion, gel electrophoresis and scanning densitometry permitted the resolution of mixed plasmid preparations into four distinct plasmids with sizes of 54 (approximately), 27.7, 22.8 and 22.6 kb. These plasmids were named pMOR1, 2, 3 and 4, respectively. The Mor+ phenotype was found to be unstable during acriflavin treatment. In four independently isolated Mor- mutants, plasmid pMOR2 was found to have acquired an insert of approximately 1.8 kb within a specific 5.9 kb BamHI fragment. It is concluded that pMOR2 is involved in the coding of the Mor+ phenotype.

Interrelationships among multidimensional competitive state anxiety components as a function of the proximity of competition

This study examined whether the relationship between the cognitive anxiety and somatic anxiety subscales of the Competitive State Anxiety Inventory-2 changes as a function of the proximity of a competition. On five separate occasions during the period prior to an important competition 87 subjects responded to the inventory. Intercorrelations between subscale scores suggested a progressive increase in the magnitude of the relationship between cognitive and somatic anxiety as the event approached. Findings support in a sporting context the hypothesis of covariance at times of high stress.

ABC of major trauma. Trauma of the spine and spinal cord--II

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ABC of major trauma. Trauma of the spine and spinal cord--I

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Performance of seven blood glucose testing systems at high altitude

Consumers and health care professionals expect blood glucose monitoring systems to consistently generate results that are close to actual blood glucose levels. Numerous environmental, physiologic, and operational factors can affect system performance, yielding results that are inaccurate or unpredictable. This study examined the effect of one factor--high altitude--on the performance of seven blood glucose monitoring systems. One of the systems overestimated blood glucose results; the other six systems underestimated blood glucose values (more than the expected variance). The findings of this study support previous reports of altered blood glucose monitoring system performance at high altitude. Diabetes educators can use this information when counseling consumers who reside or who plan to visit locations at high altitude.

Polyadenylation at correct sites in genome RNA is not required for retrovirus replication or genome encapsidation

RNA transcripts polyadenylated at sites derived from flanking cellular DNA (readthrough transcripts) make up about 15% of the viral RNA in cells infected with avian leukosis virus. To test the functionality of such transcripts, a virus was created by introducing two mutations into the AAUAAA polyadenylation signal of Rous-associated virus 1, converting it to AAGGAA. The replication of this virus was not greatly affected at any level. However, less than 1% of viral transcripts produced during mutant virus replication were cleaved and polyadenylated at the correct site within viral long terminal repeat-related sequence. These results imply that readthrough transcripts, which are produced during normal viral replication, are polyadenylated and packaged into virions as normal transcripts and can serve as RNA genomes in the next round of replication. These results show that polyadenylation within virus-related sequences is not a necessary requirement for virus replication and that readthrough transcripts have the necessary properties to be intermediates in the process of transduction of cellular sequences.

Analysis of expression and thermoregulation of the Yersinia pseudotuberculosis inv gene with hybrid proteins

A series of translational fusions between the Yersinia pseudotuberculosis inv locus and lacZ was constructed. Each Lac+ fusion strain expressed a hybrid protein containing invasin, the product of the inv locus, at its amino-terminal end. Analysis of these gene fusions allowed determination of the direction of translation of the inv gene. Previous studies of Y. pseudotuberculosis invasion have shown that entry into animal cells is temperature regulated. It is shown here that control of expression of the inv gene is also temperature regulated. phoA gene fusions to inv, when present in Y. pseudotuberculosis, were expressed at lower levels when bacteria were grown at 37 degrees C rather than at 28 degrees C. Similar fusions, in contrast, were regulated in a temperature-independent fashion in Escherichia coli, as was the wild-type inv gene. This implies that Y. pseudotuberculosis has chromosomally encoded trans-acting functions that normally thermoregulate expression of inv.