Intestinal floras of populations that have a high risk of colon cancer

The fecal floras of polyp patients, Japanese-Hawaiians, North American Caucasians, rural native Japanese, and rural native Africans were compared. The polyp patients and Japanese-Hawaiians were considered to be groups at high risk of colon cancer, and the rural native Japanese and rural native Africans were considered to be groups at low risk. The North American Caucasians were found to have a flora composition intermediate between these two groups. Fifteen bacterial taxa from the human fecal flora were significantly associated with high risk of colon cancer, and five were significantly associated with low risk of colon cancer. Total concentrations of Bacteroides species and, surprisingly, Bifidobacterium species were generally positively associated with increased risk of colon cancer. Some Lactobacillus species and Eubacterium aerofaciens, which also produces major amounts of lactic acid, showed closest associations with low risk of colon cancer.

An informal school-based peer-led intervention for smoking prevention in adolescence (ASSIST): a cluster randomised trial

BACKGROUND

Schools in many countries undertake programmes for smoking prevention, but systematic reviews have shown mixed evidence of their effectiveness. Most peer-led approaches have been classroom-based, and rigorous assessments are scarce. We assessed the effectiveness of a peer-led intervention that aimed to prevent smoking uptake in secondary schools.

METHODS

We undertook a cluster randomised controlled trial of 10 730 students aged 12-13 years in 59 schools in England and Wales. 29 schools (5372 students) were randomly assigned by stratified block randomisation to the control group to continue their usual smoking education and 30 (5358 students) to the intervention group. The intervention (ASSIST [A Stop Smoking In Schools Trial] programme) consisted of training influential students to act as peer supporters during informal interactions outside the classroom to encourage their peers not to smoke. Follow-up was immediately after the intervention and at 1 and 2 years. Primary outcomes were smoking in the past week in both the school year group and in a group at high risk of regular smoking uptake, which was identified at baseline as occasional, experimental, or ex-smokers. Analysis was by intention to treat. This study is registered, number ISRCTN55572965.

FINDINGS

The odds ratio of being a smoker in intervention compared with control schools was 0.75 (95% CI 0.55-1.01) immediately after the intervention (n=9349 students), 0.77 (0.59-0.99) at 1-year follow-up (n=9147), and 0.85 (0.72-1.01) at 2-year follow-up (n=8756). The corresponding odds ratios for the high-risk group were 0.79 (0.55-1.13 [n=3561]), 0.75 (0.56-0.99 [n=3483]), and 0.85 (0.70-1.02 [n=3294]), respectively. In a three-tier multilevel model with data from all three follow-ups, the odds of being a smoker in intervention compared with control schools was 0.78 (0.64-0.96).

INTERPRETATION

The results suggest that, if implemented on a population basis, the ASSIST intervention could lead to a reduction in adolescent smoking prevalence of public-health importance.

The association of age and semen quality in healthy men

BACKGROUND

Although the effect of maternal age on fertility is well known, it is unclear whether paternal age also affects fertility. This cross-sectional study sought to characterize the association between age and semen quality, a well-known proxy of fertility status.

METHODS

A convenience sample of 97 non-smoking men (aged 22-80 years) without known fertility problems was recruited from a national government laboratory. The men provided semen samples and information relating to lifestyle, diet, medical and occupational details. Semen volume (ml), sperm concentration (x10(6)/ml), total sperm count (x10(6)), motility (%), progressive motility (%) and total progressively motile sperm count (x10(6)) were measured.

RESULTS

After adjusting for covariates, semen volume decreased by 0.03 ml per year of age (95% CI: -0.05, -0.01); motility decreased by 0.7% per year (95% CI: -0.92, -0.43); progressive motility decreased by 3.1% per year (95% CI: -4.5, -1.6); and total progressively motile sperm count decreased by 4.7% per year (95% CI: -7.2, -2.2). There was a suggested decrease in sperm concentration and count. The proportion of men with abnormal volume, concentration and motility was significantly increased across the age decades.

CONCLUSIONS

In a convenience sample of healthy men from a non-clinical setting, semen volume and sperm motility decreased continuously between 22-80 years of age, with no evidence of a threshold.

The microflora of periodontal sites showing active destructive progression

20 adult periodontitis (AP) subjects were examined every 2 to 4 months and microbiological samples were collected and cultured when 2 mm or more loss of attachment (active sites) was detected by 2 examiners. Similar sites in which no progressive destruction was observed (control sites) also were sampled in the same subjects. By lambda-analysis, there was no statistically significant difference in floras of active (42 sites from 12 subjects) and control (36 sites from 12 subjects) sites or between the floras of the active and control sites and of 63 samples from 22 AP subjects that were examined previously in a cross-sectional study. By paired t test, no microbial species had a significantly greater association with active than with control sites. The only species that were detected in one or more samples from all subjects with active sites were Wolinella recta, Fusobacterium nucleatum, and Peptostreptococcus micros. Porphyromonas gingivalis and 9 other taxa were isolated from one-half or more of the persons with active sites. The composition of microbiological floras of all periodontitis samples was statistically significantly different from that of subjects with healthy gingiva. The composition of microfloras of sites in subjects with naturally-occurring gingivitis was intermediate between that of subjects with healthy gingiva and that of active and control sites in AP subjects.

Prostate specific antigen and local recurrence after radical prostatectomy

We evaluated the location of recurrent disease in 63 patients with carcinoma of the prostate who had abnormal levels of prostate specific antigen (greater than 0.4 ng./ml., Tandem-R assay) 6 to 240 months after radical prostatectomy but who were otherwise considered to be without evidence of disease. The evaluation involved physical examination including digital rectal examinations by 3 urologists, isotopic bone scans, computerized tomography scans of the abdomen and pelvis, cystoscopy, and random needle biopsies of the urethrovesical anastomotic area. In 6 patients metastatic disease to the bone and/or lymph nodes was found and local prostate cancer was discovered in 5. Among 57 patients without evidence of disease by the usual methods of evaluation needle biopsies of the anastomosis revealed local disease in 42%. No local disease was discovered in 30 post-radical prostatectomy patients with normal prostate specific antigen levels. There was a wide range of transrectally palpable contours after radical prostatectomy in patients with and without elevated prostate specific antigen levels. We conclude that prostate specific antigen but not digital rectal examination is an excellent early indicator of possible local recurrence after radical prostatectomy. Whether the prevalence of local disease after radical prostatectomy using prostate specific antigen levels and needle biopsies of the anastomosis is greater than heretofore has been appreciated will require further study.

C-ring cleavage of flavonoids by human intestinal bacteria

Four hitherto undescribed Clostridium strains capable of cleaving the C ring of quercetin, kaempferol, and naringenin at C-3-C-4 were isolated from the fecal flora of humans. None of the strains cleaved catechin. C-ring fission occurred when the substrate was either in solution or in suspension. Mixed cultures of flavonoid-hydrolyzing bacteria, flavonoid-cleaving bacteria, and Escherichia coli, which was used to provide the anaerobic environment, rapidly metabolized rutin to 3,4-dihydroxyphenylacetic acid, indicating that the intestinal half-life of the biologically active aglycone is short. The cleaving strains shared many phenotypic characteristics, including their inability to ferment sugars, but they differed sufficiently to indicate that they represent different species.

A family of cyclin-like proteins that interact with the Pho85 cyclin-dependent kinase

In budding yeast, entry into the mitotic cell cycle, or Start, requires the Cdc28 cyclin-dependent kinase (Cdk) and one of its three associated G1 cyclins, Cln1, Cln2, or Cln3. In addition, two other G1 cyclins, Pcl1 and Pcl2, associate with a second Cdk, Pho85, to contribute to Start. Although Pho85 is not essential for viability, Pcl1,2-Pho85 kinase complexes become essential for Start in the absence of Cln1,2-Cdc28 kinases. In addition, Pho85 interacts with a third cyclin, Pho80, to regulate acid phosphatase gene expression. Other cellular roles for Pho85 cyclin-Cdk complexes are suggested by the multiple phenotypes associated with deletion of PHO85, in addition to Start defects and deregulated acid phosphatase gene expression. Strains with pho80, pcl1, and pcl2 deletions show only a subset of the pho85 mutant phenotypes, suggesting the existence of additional Pho85 cyclins (Pcls). We used two-hybrid screening and database searching to identify seven additional cyclin-related genes that may interact with Pho85. We found that all of the new genes encode proteins that interacted with Pho85 in an affinity chromatography assay. One of these genes, CLG1, was previously suggested to encode a cyclin, based on the protein's sequence homology to Pcl1 and Pcl2. We have named the other genes PCL5, PCL6, PCL7, PCL8, PCL9, and PCL10. On the basis of sequence similarities, the PCLs can be divided into two subfamilies: the Pcl1,2-like subfamily and the Pho80-like subfamily. We found that deletion of members of the Pcl1,2 class of genes resulted in pronounced morphological abnormalities. In addition, we found that expression of one member of the Pcl1,2 subfamily, PCL9, is cell cycle regulated and is decreased in cells arrested in G1 by pheromone treatment. Our studies suggest that Pho85 associates with multiple cyclins and that subsets of cyclins may direct Pho85 to perform distinct roles in cell growth and division.

A comparison of tonsillar size and oropharyngeal dimensions in children with obstructive adenotonsillar hypertrophy

Hypertrophy of the tonsils and adenoids is the most common cause of obstructive sleep apnea in children. There is relatively little known about the occurrence of subclinical variations in the dimensions of the oropharynx which may predispose to the development of obstructive sleep apnea in children without obvious craniofacial abnormalities. Fifty-one children (3-10 years) were divided into two groups: the first group consisted of 18 patients with small tonsils and no history of snoring who underwent tonsillectomy for chronic tonsillitis. They were compared to a second group of 33 patients with large tonsils who underwent tonsillectomy and adenoidectomy for symptoms of obstructive sleep apnea. Age, height, weight, body surface area and tonsil weight were correlated to the dimensions of the oropharynx obtained by direct measurement intraoperatively including the length of the soft palate, anterior-posterior depth of the nasopharynx and the distances between the medial tonsillar surfaces, anterior tonsillar pillars and lateral pharyngeal walls at mid-tonsil level. Increased patient height, weight and surface area correlated positively to increased distance between the lateral pharyngeal walls and to the length of the soft palate in the patients with small tonsils. No such correlation existed in the patients with obstructive adenotonsillar hypertrophy. In addition, the distance between the lateral pharyngeal walls was significantly decreased in the group with large, obstructing tonsils as compared to those with small tonsils and no history of obstruction (P less than 0.01). However, the patients with small tonsils and no obstruction had significantly longer soft plates (P less than 0.01) and less depth tot eh nasopharynx (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Seizures after primary intracerebral hemorrhage

We followed 123 patients with primary intracerebral hemorrhage (ICH), defined as bleeding without known precipitating cause except hypertension, for an average of 4.6 years or until death in order to determine the incidence, prevalence, and type of epileptic seizures. Twenty-five percent had seizures. In one-half of these, the seizures began within 24 hours of the hemorrhage. Survival table analysis predicted a potential cumulative seizure incidence of 50%, had all patients survived 5 years. Seizure incidence was high with bleeding into lobar cortical structures (54%), low with basal ganglionic hemorrhages (19%), and zero with thalamic hemorrhages. Within the basal ganglia, caudate involvement predicted seizures; within the cortex, temporal or parietal involvement predicted seizures. Although seizure incidence was high, prevalence of chronic epilepsy was much lower: 13% in 30-day to 2-year survivors and 6.5% in 2- to 5-year survivors. Seizure incidence is higher than previously reported after ICH because small lobar hemorrhages are the most epileptogenic and are now easily recognized with computed tomography.

Association between natural scrapie and PrP genotype in a flock of Suffolk sheep in Scotland

The incidence of natural scrapie in sheep is associated with polymorphisms of the PrP gene, particularly those at codons 136, 154 and 171. In many breeds, the PrP allele encoding valine at codon 136 confers an extremely high risk of scrapie, but in Suffolk sheep this allele is vanishingly rare. In this study of a single closed flock of Suffolk sheep in Scotland, scrapie occurred primarily in animals which were homozygous for glutamine at codon 171, a genotype which was significantly less frequent in healthy flockmates. However, the apparent linkage between glutamine at codon 171 and scrapie was not completely recessive because two of 64 scrapie cases were heterozygous glutamine/arginine. These results suggest that breeding for increased resistance to scrapie in Suffolks by the selection of animals according to their PrP genotype is a feasible option.

The PCL2 (ORFD)-PHO85 cyclin-dependent kinase complex: a cell cycle regulator in yeast

Cyclin-dependent kinase (cdk) complexes are essential activators of cell cycle progression in all eukaryotes. In contrast to mammalian cells, in which multiple cdk's contribute to cell cycle regulation, the yeast cell cycle is largely controlled by the activity of a single cdk, CDC28. Analysis of the putative G1 cyclin PCL2 (ORFD) identified a second cyclin-cdk complex that contributes to cell cycle progression in yeast. PCL2 interacted with the cdk PHO85 in vivo and in vitro and formed a kinase complex that had G1-periodic activity. Under genetic conditions in which the Start transition was compromised, PHO85 and its associated cyclin subunits were essential for cell cycle commitment. Because PHO85 and another cyclin-like molecule, PHO80, also take part in inorganic phosphate metabolism, this cdk enzyme may integrate responses to nutritional conditions with the cell cycle.

School smoking policies and smoking prevalence among adolescents: multilevel analysis of cross-sectional data from Wales

OBJECTIVE

To examine the association between school smoking policies and smoking prevalence among pupils.

DESIGN

Multilevel analysis of cross-sectional data from surveys of schools and pupils.

SETTING

55 secondary schools in Wales.

SUBJECTS

55 teachers and 1375 pupils in year 11 (aged 15-16).

MAIN OUTCOME MEASURES

Self-reported smoking behaviour.

RESULTS

The prevalence of daily smoking in schools with a written policy on smoking for pupils, teachers, and other adults, with no pupils or teachers allowed to smoke anywhere on the school premises, was 9.5% (95% confidence interval (CI) 6.1% to 12.9%). In schools with no policy on pupils' or teachers' smoking, 30.1% (95% CI 23.6% to 36.6%) of pupils reported daily smoking. In schools with an intermediate level of smoking policy, 21.0% (95% CI 17.8% to 24.2%) smoked every day. School smoking policy was associated with school level variation in daily smoking (p = 0.002). In multilevel analysis, after adjusting for pupils' sex, parents' and best friends' smoking status, parental expectations, and alienation from school, there was less unexplained school level variation, but school smoking policy remained significant (p = 0.041). The association of smoking policy with weekly smoking was weaker than for daily smoking, and not significant after adjustment for pupil level variables. Both daily and weekly smoking prevalence were lower in schools where pupils' smoking restrictions were always enforced. Enforcement of teacher smoking restrictions was not significantly associated with pupils' smoking.

CONCLUSIONS

This study demonstrates an association between policy strength, policy enforcement, and the prevalence of smoking among pupils, after having adjusted for pupil level characteristics. These findings suggest that the wider introduction of comprehensive school smoking policies may help reduce teenage smoking.

Systematic review of the effects of schools and school environment interventions on health: evidence mapping and synthesis

Background

In contrast to curriculum-based health education interventions in schools, the school environment approach promotes health by modifying schools' physical/social environment. This systematic review reports on the health effects of the school environment and processes by which these might occur. It includes theories, intervention outcome and process evaluations, quantitative studies and qualitative studies.

Research questions

Research question (RQ)1: What theories are used to inform school environment interventions or explain school-level health influences? What testable hypotheses are suggested? RQ2: What are the effects on student health/inequalities of school environment interventions addressing organisation/management; teaching/pastoral care/discipline; and the physical environment? What are the costs? RQ3: How feasible/acceptable and context dependent are such interventions? RQ4: What are the effects on student health/inequalities of school-level measures of organisation/management; teaching/pastoral care/discipline; and the physical environment? RQ5: Through what processes might such influences occur?

Data sources

A total of 16 databases were searched between 30 July 2010 and 23 September 2010 to identify relevant studies, including the British Educational Index, the Cumulative Index to Nursing and Allied Health Literature, the Health Management Information Consortium, EMBASE, MEDLINE and PsycINFO. In addition, references of included studies were checked and authors contacted.

Review methods

In stage 1, we mapped references concerning how the school environment affects health and consulted stakeholders to identify stage 2 priorities. In stage 2, we undertook five reviews corresponding to our RQs.

Results

Stage 1: A total of 82,775 references were retrieved and 1144 were descriptively mapped. Stage 2: A total of 24 theories were identified (RQ1). The human functioning and school organisation, social capital and social development theories were judged most useful. Ten outcome evaluations were included (RQ2). Four US randomised controlled trials (RCTs) and one UK quasi-experimental study examined interventions building school community/relationships. Studies reported benefits for some, but not all outcomes (e.g. aggression, conflict resolution, emotional health). Two US RCTs assessed interventions empowering students to contribute to modifying food/physical activity environments, reporting benefits for physical activity but not for diet. Three UK quasi-experimental evaluations examined playground improvements, reporting mixed findings, with benefits being greater for younger children and longer break times. Six process evaluations (RQ3) reported positively. One study suggested that implementation was facilitated when this built on existing ethos and when senior staff were supportive. We reviewed 42 multilevel studies, confining narrative synthesis to 10 that appropriately adjusted for confounders. Four UK/US reports suggested that schools with higher value-added attainment/attendance had lower rates of substance use and fighting. Three reports from different countries examined school policies on smoking/alcohol, with mixed results. One US study found that schools with more unobservable/unsupervised places reported increased substance use. Another US study reported that school size, age structure and staffing ratio did not correlate with student drinking. Twenty-one qualitative reports from different countries (RQ5) suggested that disengagement, lack of safety and lack of participation in decisions may predispose students to engage in health risks.

Limitations

We found no evidence regarding health inequalities or cost, and could not undertake meta-analysis.

Conclusions

There is non-definitive evidence for the feasibility and effectiveness of school environment interventions involving community/relationship building, empowering student participation in modifying schools' food/physical activity environments, and playground improvements. Multilevel studies suggest that schools that add value educationally may promote student health. Qualitative studies suggest pathways underlying these effects. This evidence lends broad support to theories of social development, social capital and human functioning and school organisation. Further trials to examine the effects of school environment modifications on student health are recommended.

Funding

The National Institute for Health Research Public Health Research programme.

Selective amplification of additional members of the ADP-ribosylation factor (ARF) family: cloning of additional human and Drosophila ARF-like genes

The ADP-ribosylation factor (ARF) family is one of four subfamilies of the RAS superfamily of low molecular weight GTP-binding proteins (G proteins). Highly degenerate oligonucleotides encoding two conserved regions were used in a PCR reaction to amplify cDNAs encoding each of the known ARF proteins and eight additional cDNA fragments encoding previously unreported human members of the ARF family. Additional sequences were obtained from yeast or fly libraries by using this technique. These oligonucleotides specifically amplify members of the ARF family but not the structurally related G protein alpha subunits or members of the other three subfamilies of the RAS superfamily. Fragments obtained by PCR were used to obtain full-length sequences encoding highly homologous ARF-like (ARL) gene products from human and Drosophila melanogaster libraries, termed ARL2 and Ar184F, respectively. The encoded proteins are each 184 amino acids long and are 76% identical, with 40-45% identity to human ARF1 and Drosophila arf-like (arl) proteins. These genes appear to be generally expressed in human tissues and during Drosophila development. The purified human ARL2 protein differed in several biochemical properties from human ARF proteins, including the complete absence of ARF activity. Thus, the ARF family of low molecular weight GTP-binding proteins includes at least 15 distinct but structurally conserved members, including both the functionally conserved ARF proteins and the functionally disparate ARL proteins. The latter proteins currently comprise two distinct gene products in Drosophila (arl and ARL84F) and one in man (ARL2).

Flow through, immunomagnetic cell separation

A brief, process-oriented overview of immunologically based cell separation technology is presented. In addition, the design and preliminary experimental data of two unique flow-through immunomagnetic cell separation devices are presented. The first design is based on a dipole magnetic field, while the second design is basis on a quadrupole magnetic field. The dipole design can "fractionate" an inlet, magnetically labeled, cell stream into different outlet streams on the basis of the degree to which the cell is immunomagnetically labeled. The quadrupole separator splits an inlet, immunomagnetically labeled, cell stream into two outlet streams in which the purity, recovery, and potentially the degree to which the cells are immunomagnetically labeled is controlled by the flow rates in the inlet and outlet flows. A 99% purity and 86% recovery have been achieved with this system. Some distinct advantages of these two systems are the potential of high purity, recovery, and throughput at a cost which is potentially significantly lower than current, comparable technologies.

Plant antitumor agents. 30. Synthesis and structure activity of novel camptothecin analogs

A large number of camptothecin (CPT) analogs have been prepared in the 20S, 20RS, and 20R configurations with a number of ring A substituents. Topoisomerase I (T-I) inhibition data (IC50) have been obtained by standard procedures. In general, substitution at the 9 or 10 positions with amino, halogeno, or hydroxyl groups in compounds with 20S configuration results in compounds with enhanced T-I inhibition. Compounds in the 20RS configuration were less active in vitro and in vivo and those in the 20R configuration were inactive. Compounds with 10,11-methylenedioxy substitution on ring A displayed a marked increase in potency in the T-I inhibition assay. The activities of some of the analogs as determined in a variety of in vivo assays including the L-1210 mouse leukemia assay were, in general, in accord with T-I inhibition. A number of water-soluble analogs such as 20-glycinate esters, 9-glycinamides, or hydrolyzed lactone salts were prepared and tested in in vitro and in vivo assays. In general, these compounds were less active than CPT both in terms of T-I inhibition and life prolongation in the L-1210 assay. However, certain 20-glycinate esters showed good in vivo activity after iv administration.

Cyclin partners determine Pho85 protein kinase substrate specificity in vitro and in vivo: control of glycogen biosynthesis by Pcl8 and Pcl10

In Saccharomyces cerevisiae, PHO85 encodes a cyclin-dependent protein kinase (Cdk) with multiple roles in cell cycle and metabolic controls. In association with the cyclin Pho80, Pho85 controls acid phosphatase gene expression through phosphorylation of the transcription factor Pho4. Pho85 has also been implicated as a kinase that phosphorylates and negatively regulates glycogen synthase (Gsy2), and deletion of PHO85 causes glycogen overaccumulation. We report that the Pcl8/Pcl10 subgroup of cyclins directs Pho85 to phosphorylate glycogen synthase both in vivo and in vitro. Disruption of PCL8 and PCL10 caused hyperaccumulation of glycogen, activation of glycogen synthase, and a reduction in glycogen synthase kinase activity in vivo. However, unlike pho85 mutants, pcl8 pcl10 cells had normal morphologies, grew on glycerol, and showed proper regulation of acid phosphatase gene expression. In vitro, Pho80-Pho85 complexes effectively phosphorylated Pho4 but had much lower activity toward Gsy2. In contrast, Pcl10-Pho85 complexes phosphorylated Gsy2 at Ser-654 and Thr-667, two physiologically relevant sites, but only poorly phosphorylated Pho4. Thus, both the in vitro and in vivo substrate specificity of Pho85 is determined by the cyclin partner. Mutation of PHO85 suppressed the glycogen storage deficiency of snf1 or glc7-1 mutants in which glycogen synthase is locked in an inactive state. Deletion of PCL8 and PCL10 corrected the deficit in glycogen synthase activity in both the snf1 and glc7-1 mutants, but glycogen synthesis was restored only in the glc7-1 mutant strain. This genetic result suggests an additional role for Pho85 in the negative regulation of glycogen accumulation that is independent of Pcl8 and Pcl10.

The Drosophila kismet gene is related to chromatin-remodeling factors and is required for both segmentation and segment identity

The Drosophila kismet gene was identified in a screen for dominant suppressors of Polycomb, a repressor of homeotic genes. Here we show that kismet mutations suppress the Polycomb mutant phenotype by blocking the ectopic transcription of homeotic genes. Loss of zygotic kismet function causes homeotic transformations similar to those associated with loss-of-function mutations in the homeotic genes Sex combs reduced and Abdominal-B. kismet is also required for proper larval body segmentation. Loss of maternal kismet function causes segmentation defects similar to those caused by mutations in the pair-rule gene even-skipped. The kismet gene encodes several large nuclear proteins that are ubiquitously expressed along the anterior-posterior axis. The Kismet proteins contain a domain conserved in the trithorax group protein Brahma and related chromatin-remodeling factors, providing further evidence that alterations in chromatin structure are required to maintain the spatially restricted patterns of homeotic gene transcription.

A motility function for the paraflagellar rod of Leishmania parasites revealed by PFR-2 gene knockouts

We demonstrate a functional role for the paraflagellar rod (PFR) in motility of Leishmania mexicana. The PFR is a complex cytoskeletal structure running parallel to the axoneme in the flagella of kinetoplastid protozoa. The PFR is composed of a latticework of protein filaments whose major constituents are two related proteins (PFR-1 and PFR-2 in Leishmania). The molecular details of their assembly into PFR filaments are unknown as is the biological function of the PFR. As an approach to understanding the structure and function of the PFR in Leishmania, we made L. mexicana null mutants of PFR-2. PFR-2 minus parasites grow and divide normally in culture and still express the PFR-1 protein. They lack most of the PFR structure demonstrating that the PFR-2 protein is an essential constituent of the PFR. Detailed ultrastructural analysis of the PFR-2 null mutant reveals the presence of a residual inner substructure of the PFR which contains PFR-1 protein, indicating that PFR-1 can polymerize in the absence of PFR-2. The PFR-2 null mutant displays pronounced changes in flagellar beat waveform and forward swimming velocity, compared to wild type parasites consistent with decreased internal elastic bending resistance in PFR-lacking flagella, and indicating a functional role for the PFR in the motility of Leishmania.

When Racial Ambivalence Evokes Negative Affect, Using a Disguised Measure of Mood

Many White people simultaneously hold both sympathetic and antagonistic attitudes toward Blacks. The present research found that activation of these conflicted racial attitudes gives rise to psychological tension and discomfort, as evidenced by negative mood change, and that the amount of discomfort depends on individual differences in measured ambivalence. The salience of Mite subjects' racial attitudes was manipulated by exposing half the subjects to controversial statements about a recent local incident of racial violence; the other half read neutral material Before and after this manipulation, subjects took a mood test disguised as a subliminal perception task. Subjects in the high-salience condition showed significantly more negative mood change. This effect was carried by high-salience subjects who were also relatively high on dispositional racial ambivalence, as measured by a questionnaire. Ambivalence was unrelated to mood in the control condition. A second study showed that merely completing the questionnaire was not sufficient to produce negative mood change.

The trithorax group gene osa encodes an ARID-domain protein that genetically interacts with the brahma chromatin-remodeling factor to regulate transcription

The trithorax group gene brahma (brm) encodes the ATPase subunit of a chromatin-remodeling complex involved in homeotic gene regulation. We report here that brm interacts with another trithorax group gene, osa, to regulate the expression of the Antennapedia P2 promoter. Regulation of Antennapedia by BRM and OSA proteins requires sequences 5′ to the P2 promoter. Loss of maternal osa function causes severe segmentation defects, indicating that the function of osa is not limited to homeotic gene regulation. The OSA protein contains an ARID domain, a DNA-binding domain also present in the yeast SWI1 and Drosophila DRI proteins. We propose that the OSA protein may target the BRM complex to Antennapedia and other regulated genes.

Sedentary behaviour, physical activity and weight problems in adolescents in Wales

OBJECTIVE

We studied the prevalence and stability of overweight and obesity in a cohort of adolescents, and the effects of sedentary behaviour and physical activity on changes in body mass. The study also examined the extent to which physical activity mediated the relationship between sedentary behaviour and body mass.

DESIGN

Four-year cohort study.

METHODS

The study was part of the Health Behaviour of School-aged Children Study that took place in Wales between 1994 and 1998. Body height and weight measurements and self-report data on sedentary behaviour, physical activity and psychosocial adjustment were collected from 355 adolescents on two occasions 4 years apart. The mean age of the sample at baseline was 12.30 (SD=6.30) years.

RESULTS

Weight conditions (underweight, overweight and obesity) and body mass were moderately stable over the interval. Regression analyses showed that sedentary behaviour at Time 1 predicted body mass at Time 2, while physical activity predicted a change in body mass over time. The influence of sedentary behaviour on body mass was not found to be mediated by physical activity. However, weight problems in Year 7 coincided with getting bullied, bullying others, and feeling left out of things. Obesity was also related to snacking and skipping breakfast.

CONCLUSIONS

Sedentary behaviour and physical activity in early adolescence both influenced body mass in late adolescence. Results indicated that promoting healthy diets and physical activities may have long-term health benefits for young people.