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Control Pairs (control + pair)
Selected AbstractsOptimal control of an HIV immunology modelOPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 4 2002Hem Raj Joshi Abstract A system of ordinary differential equations, which describes the interaction of HIV and T -cells in the immune system is utilized, and optimal controls representing drug treatment strategies of this model are explored. Two types of treatments are used, and existence and uniqueness results for the optimal control pair are established. The optimality system is derived and then solved numerically using an iterative method with a Runge,Kutta fourth order scheme. Copyright © 2002 John Wiley & Sons, Ltd. [source] Social context affects testosterone-induced singing and the volume of song control nuclei in male canaries (Serinus canaria)DEVELOPMENTAL NEUROBIOLOGY, Issue 10 2006Géraldine Boseret Abstract The contribution of social factors to seasonal plasticity in singing behavior and forebrain nuclei controlling song, and their interplay with gonadal steroid hormones are still poorly understood. In many songbird species, testosterone (T) enhances singing behavior but elevated plasma T concentrations are not absolutely required for singing to occur. Singing is generally produced either to defend a territory or to attract a mate and it is therefore not surprising that singing rate can be influenced by the sex and behavior of the social partner. We investigated, based on two independent experiments, the effect of the presence of a male or female partner on the rate of song produced by male canaries. In the first experiment, song rate was measured in dyads composed of one male and one female (M-F) or two males (M-M). Birds were implanted with T-filled Silastic capsules or with empty capsules as control. The number of complete song bouts produced by all males was recorded during 240 min on week 1, 2, 4, and 8 after implantation. On the day following each recording session, brains from approximately one-fourth of the birds were collected and the volumes of the song control nuclei HVC and RA were measured. T increased the singing rate and volume of HVC and RA but these effects were affected by the social context. Singing rates were higher in the M-M than in the M-F dyads. Also, in the M-M dyads a dominance-subordination relationship soon became established and dominant males sang at higher rates than subordinates in T-treated but not in control pairs. The differences in song production were not reflected in the size of the song control nuclei: HVC was larger in M-F than in M-M males and within the M-M dyads, no difference in HVC or RA size could be detected between dominant and subordinate males. At the individual level, the song rate with was positively correlated with RA and to a lower degree HVC volume, but this relationship was observed only in M-M dyads, specifically in dominant males. A second experiment, carried out with castrated males that were all treated with T and exposed either to another T-treated castrate or to an estradiol-implanted female, confirmed that song rate was higher in the M-M than in the M-F condition and that HVC volume was larger in heterosexual than in same-sex dyads. The effects of T on singing rate and on the volume of the song control nuclei are thus modulated by the social environment, including the presence/absence of a potential mate and dominance status among males. 2006 Wiley Periodicals, Inc. J Neurobiol, 2006 [source] Maternal carotenoid supplementation does not affect breeding performance in the Great Tit (Parus major)FUNCTIONAL ECOLOGY, Issue 4 2007VLADIMÍR REME Summary 1Carotenoids are micronutrients with many beneficial health-related effects. They are effective antioxidants and stimulants of the immune system. Carotenoids cannot be synthesized in animals and must be obtained from food. As such, they may limit reproductive output and performance, and on the proximate level mediate reproductive trade-offs. 2We studied carotenoid limitation in wild Great Tits (Parus major) by supplementing prelaying and laying females with lutein, the most abundant carotenoid in this species. We followed the effects of this supplementation on egg yolk carotenoid composition, and offspring and parental performance. 3Females transferred the supplemented lutein into egg yolks, increasing lutein concentration to the upper limit of naturally occurring concentrations in control pairs. Concentrations of zeaxanthin, ,-carotene and ,-carotene did not differ between supplemented and control pairs. 4Effects on offspring and parental performance were generally absent or weak. There were no effects on timing of laying, clutch size, hatching success, nestling survival, nestling mass (day 6 and 14), tarsus length or T-cell mediated immune response. Males on supplemented nests fed their young more than those on control nests. There was no positive effect on female feeding or mass. 5Negligible effects of lutein supplementation on offspring and parental performance might be explained by high natural abundance of carotenoids or other antioxidants, where additional carotenoids bear no strong advantage to the birds. Additionally, conflicting results of different studies may be explained by species-specific features of their life-histories. [source] Dietary intake in sensitized children with recurrent wheeze and healthy controls: a nested case,control studyALLERGY, Issue 4 2006C. S. Murray Background:, The rising prevalence of asthma and allergic disease remains unexplained. Several risk factors have been implicated including diet, in particular poly-unsaturated fats and antioxidant intake. Methods:, A nested case,control study comparing the dietary intake of sensitized children with recurrent wheeze (age 3,5 years) and nonsensitized children who had never wheezed was carried out within an unselected population-based cohort. Cases and controls were matched for age, sex, parental atopy, indoor allergen exposure and pet ownership. Dietary intake was assessed using a validated semi-quantitative food frequency questionnaire and nutrient analysis program. Results:, Thirty-seven case,control pairs (23 male, mean age 4.4 years) participated. Daily total polyunsaturated fat intake was significantly higher in sensitized wheezers (g/day, geometric mean, 95% confidence intervals: 7.1, 6.4,7.9) compared with nonsensitized nonwheezy children (5.6, 5.0,6.3, P = 0.003). Daily omega-3 and omega-6 fat intakes were not significantly different between the two groups. No significant differences were found in intake of any antioxidant or antioxidant cofactors between the groups. Conclusions:, Young sensitized wheezy children had a significantly higher total polyunsaturated fat intake compared with nonsensitized nonwheezy children. However, we were unable to distinguish a significant difference in specific poly-unsaturated fat intakes. Otherwise the children in both groups had a very similar nutritional intake. [source] Coffee, caffeine-related genes, and Parkinson's disease: A case,control study,MOVEMENT DISORDERS, Issue 14 2008Maurizio F. Facheris MD Abstract An inverse association between coffee and Parkinson's disease (PD) has been reported. However, it remains uncertain why some but not all coffee drinkers are less susceptible to PD. We considered the possibility of a pharmacogenetic effect. In our study, we included 1,208 subjects (446 case-unaffected sibling pairs and 158 case-unrelated control pairs) recruited from an ongoing study of the molecular epidemiology of PD in the Upper Midwest (USA). We collected information on lifetime coffee drinking and we studied two genes: ADORA2A, which encodes the major receptor activity of caffeine in the brain (variants rs5751876 and rs3032740), and CYP1A2, which encodes the major rate-limiting step of caffeine metabolism (variants rs35694136 and rs762551). We did not observe significant associations of coffee drinking or of the genetic variants with PD susceptibility, either independently or jointly, in the sample overall and in most strata. Our study neither supports the hypothesis that coffee protects against PD nor provides evidence for a pharmacogenetic effect. © 2008 Movement Disorder Society [source] Metabolic effects and the methylenetetrahydrofolate reductase (MTHFR) polymorphism associated with neural tube defects in southern Brazil,BIRTH DEFECTS RESEARCH, Issue 7 2004Têmis Maria Félix Abstract BACKGROUND The importance of metabolic factors in neural tube defects (NTDs) has been the focus of many investigations. Several authors have suggested that abnormalities in homocysteine metabolism, such as hyperhomocysteinemia, folate deficiency, and low vitamin B12, may be responsible for these malformations and that both nutritional factors and genetic abnormalities are associated with them. METHODS We conducted a case-control study to investigate the influence of biochemical and genetic factors in NTDs in infants in southern Brazil. Levels of folate, vitamin B12, total homocysteine (t-Hcy) and the 677C>T and 1298A>C polymorphisms of the MTHFR gene were analyzed in 41 NTD child,mother pairs and 44 normal child,mother control pairs. RESULTS Subjects in the case group had a higher mean blood folate level than those in the control group. The level of vitamin B12 was lower in mothers in the NTD group than in control mothers (p = 0.004). The level of t-Hcy was not different in the two groups, but t-Hcy and vitamin B12 were correlated (p = 0.002). There was no difference in the genotype distribution for 677C>T and 1298A>C polymorphisms of MTHFR in the case and control pairs. The level of t-Hcy was correlated with 677TT. CONCLUSIONS Despite the small sample in this study, we suggest that low vitamin B12 and, consequently, hyperhomocysteinemia are important risk factors for NTDs in our population. Birth Defects Research (Part A), 2004. © 2004 Wiley-Liss, Inc. [source] Triage Presenting Complaint Descriptions Bias Emergency Department Waiting TimesACADEMIC EMERGENCY MEDICINE, Issue 8 2008Martin J. Dutch BMedSci Abstract Objectives:, The authors aimed to determine whether certain emergency department (ED) triage "presenting complaint" descriptions are associated with shorter or longer waiting times, when compared with matched controls. Methods:, This was a retrospective, analytical study in three tertiary referral EDs. Data relating to adult patients with Australasian National Triage Scale (NTS) Category 3,5 complaints, who presented over 1 year, were accessed. A pilot study of 25 emergency physicians (EPs) identified five most liked and five most disliked presenting complaints. For each liked or disliked complaint, "cases" were identified using key words and phrases in the triage presentation description. For each case, the previous presentation at that institution with the same NTS category was used as a "control." Cases and controls were compared for waiting time and proportions seen within the Australasian College for Emergency Medicine (ACEM)-recommended waiting times. Results:, Data on 28,566 case,control pairs were examined. Compared to their controls, three of the five most liked complaints (dislocations, fractures, and palpitations) had significantly shorter waiting times, and significantly more were seen within the recommended waiting times (p < 0.05). In contrast, three of the five most disliked complaints (dizziness, constipation, and back pain) had significantly longer waiting times, and significantly fewer were seen within the recommended waiting times (p < 0.05). Other presenting complaints showed similar, although nonsignificant, trends. Conclusions:, Waiting times for patients with certain presenting complaints are significantly associated with triage presenting complaint descriptions. It is likely that these descriptions allow EPs to selectively seek or avoid patients with liked or disliked complaints, respectively. The impact of this for patients and ED flow needs investigation. [source] Fecal microbiota in sensitized wheezy and non-sensitized non-wheezy children: a nested case,control studyCLINICAL & EXPERIMENTAL ALLERGY, Issue 6 2005C. S. Murray Summary Background It has been suggested that intestinal microbiota of allergic and non-allergic children differs in composition, and that microbiota,immune system interactions may predispose children to develop sensitization. Previous studies have examined fecal microbiota of allergic children with atopic dermatitis, but little is known about that of atopic wheezy children. Objective To investigate the composition of the fecal microbiota of young sensitized wheezy and non-sensitized non-wheezy children, using molecular methods. Methods Within the context of a prospective birth cohort, we carried out a nested case,control study of sensitized wheezy children (cases) and non-sensitized non-wheezy controls. Cases and controls were matched for age, sex, parental atopy, allergen exposure, and pet ownership. We evaluated the composition of fecal microbiota by nucleic acid-based methods (PCR combined with denaturing gradient gel electrophoresis and quantification of bifidobacteria by fluorescent in situ hybridization). Results Thirty-three case,control pairs (mean age 4.4 years) provided stool samples. Comparison of total bacterial community profiles showed that each child had a unique fecal microbiota (mean Dice's similarity coefficient 22%, range 3.3,60.8%). There was no difference between the groups in prevalence of Lactic Acid bacteria (12/33 vs. 11/33, P=0.8) or bifidobacteria (30/33 vs. 31/33, P=1.00, cases vs. controls). The bifidobacterial species detected were similar in both groups. The percentage of bifidobacteria in total fecal microflora was no different between cases (median 1.7%, range 0,20.8%) and controls (1.9%, 0,18.2%, P=0.7). However, cases with eczema had significantly fewer bifidobacteria (median 1.6%, range 0,4.8%) than their controls (4.0%, 1.9,18.2%, P=0.05). Conclusion We found no differences in fecal microbiota composition between sensitized wheezy and non-sensitized, non-wheezy children aged 3,5 years using nucleic acid-based methods. Differences appear to be isolated to those allergic children with eczema. [source] | |||||||||||||