Nuo to, kaip elgiasi individas priklauso, kokia bus jo sveikata. Sveikatai žalingas elgesys turi daug formų: alkoholio, tabako, kitų narkotinių medžiagų vartojimas, neatsakingas ar per ankstyvas lytinis aktyvumas. Tyrėjai yra pastebėję, jog lytinės brandos pradžia ir alkoholio vartojimas padidėjęs depresiškumas, ankstyvas seksualinis gyvenimas turi glaudžių sąsajų. Darbo tikslas – ištirti ankstyvosios lytinės brandos ir draugų elgesio sąsajas su sveikatai žalingu elgesiu paauglystėje. Palyginti ankstyvosios lytinės brandos paauglių, turinčių draugų, kuriems būdingas sveikatai žalingas elgesys, elgesį, su tokių draugų turinčių, kito lytinės brandos statuso paauglių elgesiu. Tyrime naudotas Jessor R. modifikuotas probleminio elgesio klausimynas, bei lytinio brendimo skalė. Tyrime dalyvavo 198 (84 berniukai ir 114 mergaitės) 14 – 19 metų tiriamieji amžius. Iš jų 50 buvo priskirti ankstyvosios lytinės bandos grupei. Tyrimo rezultatai atskleidė, jog sveikatai žalingas elgesys yra labiau būdingas berniukams negu mergaitėms, taip pat, kad ankstyvoji lytinė branda turi mažai sąsajų su sveikatai žalingo elgesio pasireiškimu ir tai, jog yra daugiau sąsajų tarp draugų elgesio ir sveikatai žalingo elgesio pasireiškimo, negu tarp sveikatai žalingo elgesio pasireiškimo ir ankstyvosios lytinės brandos. / Pubertal processes have a major effect on physical, psychological, and social development. Early pubertal timing is associated with early initiation of alcohol, sexual behaviour, drug use and deviance in adolescence. The aim of this study was to examine the relationship between pubertal statuses, peer behaviour and health behaviour in adolescence. Children reported their pubertal development status and timing using a self-report Pubertal Development Scale and Jessor R. questionnaire of Problem Behaviour. There were 198 (84 boys and 98 girls) investigate in the study. The findings demonstrated that boys were more likely than girls to use alcohol, drugs and have early sexual intercourse. There were no associations between puberty, peer behaviour and health behaviour, but there are association between peer behaviour and health behaviour.

Biological factors regulating feed efficiency were investigated in replacement beef heifers to establish factors that differ between efficient and less efficient animals. Feed efficiency, measured as residual feed intake (RFI) adjusted for body ultrasound measurements, was determined in forty-seven cross-bred heifers. Reproductive differences between efficient (low RFI) and less efficient (high RFI) heifers were examined. Low RFI heifers had an earlier age at both sexual maturity (P=0.08) and conception (P=0.08), and delivered heavier calves (P=0.006). The potential of fecal progesterone metabolites (FP4M) as an indicator of sexual maturity was examined. Measurements of FP4M present a promising non-invasive alternative technique for determining the onset of sexual maturity. A subset of 36 heifers was used to determine if plasma triiodothyronine (T3) concentrations could be used to predict feed efficiency. Triiodothyronine concentrations a correlation of 0.58 (P=0.001) to those from a quadratic prediction model of RFI in heifers sampled as yearlings. / Research into reproductive characteristics associated with residual feed intake, and to determine the effectiveness of the thyroid hormones as a screening tool for feed efficient animals. / OMAFRA (Ontario Ministry of Agriculture, Food, and Rural Affairs) through the Farm Innovation Program, Agriculture Canada through the Growing Forward Project, the Canadian Cattlemen’s Association through the Beef Cattle Research Council, and the Ontario Cattlemen’s Association.

Viena iš svarbiausių daugiamečio sportinio rengimo veiksmingumo sąlygų yra tikslingas profesionalus rengimo valdymas: multispektrinis ir daugiamokslinis vyksmas – tikslingas atleto sportinio parengtumo gerinimas, įgyvendinant numatytas pratybų ir varžybų programas Būtina veiksmingo sportinio rengimo valdymo sąlyga – svarbiausių veiksnių, labiausiai lemiančių jaunųjų krepšininkų sportinį parengtumą ir sportinių rezultatų gerėjimą, geriausių rezultatų siekimą, pažinimas. Tai svarbu todėl, kad krepšininkų žaidimo kokybė, sėkmė svarbiausiose varžybose priklauso nuo daugelio veiksnių. Deja, pasigendama tyrimų, nagrinėjančių pagrindinių jaunųjų krepšininkų morfologinių ir greitumo jėgos rodiklių priklausomybę, jų įtaką fiziniam jaunųjų krepšininkų parengtumui. Iškyla aktuali mokslinė problema – nustatyti jaunųjų krepšininkų morfologinių ir greitumo jėgos rodiklius, jų kaitą ir tarpusavio ryšį brendimo laikotarpiu. Tyrimo objektas – jaunųjų krepšininkų morfologiniai ir greitumo jėgos rodikliai, jų kaita ir tarpusavio ryšys. Tyrimo tikslas – nustatyti ir įvertinti jaunųjų krepšininkų morfologinius ir greitumo jėgos rodiklius, jų kaitą ir tarpusavio ryšį brendimo laikotarpiu. Tyrimo uždaviniai: 1. Nustatyti ir įvertinti pagrindinius jaunųjų krepšininkų morfologinius rodiklius ir jų kaitą. 2. Nustatyti ir įvertinti greitumo jėgos rodiklius ir jų kaitą. 3. Nustatyti morfologinių ir greitumo jėgos rodiklių tarpusavio ryšį. Tyrimo metodai Tyrimo uždaviniams spręsti buvo taikyti tokie... [toliau žr. visą tekstą] / One of the most significant conditions for the effective long-term athlete training is a purposeful professional control of training: multispectral and interdisciplinary process focused on the improvement of athletic training by implementing planned programs of training sessions and competitions. An essential condition for effective athletic training is the understanding of the most important factors influencing athletic fitness and increased sport performance in young basketball players. The quality of their play and the success in the main competitions depend on a series of factors. This awareness and the lack of previous studies analysing interdependence between the key morphological characteristics and the indicators of velocity power as well as their influence on physical fitness in young players make this scientific problem to determine morphological characteristics and the indicators of velocity power in young basketball players, their change and correlation during puberty relevant. Object of the study: morphological characteristics and indicators of velocity power in young basketball players, their change and interrelations. Aim of the study is to determine and evaluate morphological characteristics and indicators of velocity power, their change and correlation during the period of puberty. Objectives of the study: 4. To determine and evaluate the main morphological characteristics in young basketball players and their change. 5. To determine and evaluate indicators... [to full text]

Leptin is a peripheral adiposity signal and a key hormone in energy balance regulation in mammals, acting as a link between nutritional status and the endocrine reproductive axis. If this is also the role of leptin in fish is not fully understood. This thesis investigates how different components of the leptin system are affected by sexual maturation and seasonal changes in energy balance in male Atlantic salmon (Salmo salar L.) parr under fully fed and feed-restricted conditions. Moreover, the role of sex steroids as being one of the possible mechanisms by which sexual maturation interacts with leptin is explored. The salmon leptin-a genes, lepa1 and lepa2, were expressed mainly in liver and the leptin receptor (lepr) in brain and ubiquitously in peripheral tissues. Seasonal characterization of the lepa genes and lepr during the growth and reproductive season in one-year old males showed that hepatic lepa1 and lepa2 mRNA levels and plasma leptin levels were down-regulated concomitantly with an increase in weight and body fat. Feed restriction up-regulated hepatic leptin, and pituitary lepr expression as well as plasma leptin levels. Correlation between leptin levels and body lipid stores were either lacking or negative. These findings show that leptin and lepr are sensitive to changes in energy balance, but that leptin might not reflect adiposity in juvenile salmon. Hepatic lepa1 and lepa2, and testicular lepr expression increased during mid- to late spermatogenesis in early maturing males. This up-regulation was preceded by rapid gonadal growth and elevated pituitary follicle-stimulating hormone gene expression levels, whereas peak leptin levels coincided with peak pituitary luteinizing hormone expression and the presence of running milt in the testes. The sex steroids testosterone (T), 11-ketotestosterone and 17-β estradiol stimulated lepa1 and lepa2 gene expression in Atlantic salmon hepatocytes in vitro differentially depending on developmental stage. T was also able to stimulate hepatic lepa1 and pituitary lepa1 and lepr gene expression in immature male salmon in vivo. These results suggest that leptin plays a role in male fish reproduction during later stages of the maturational process and that the elevation of leptin expression during spermatogenesis could be caused by androgen stimulation.

Sexual maturation during commercial culture of Atlantic cod (Gadus morhua L.) represents a significant production bottleneck restricting the profitability of the industry. Such problems in other species have traditionally been addressed by artificial manipulation of photoperiod cycles, however little research exists in this field in cod. This thesis therefore investigates the interactions between artificial photoperiod manipulation, sexual maturation and somatic growth in this species. In the first experiment, populations of Atlantic cod (hatched, spring 1999) were maintained on either a simulated natural photoperiod (SNP) or continuous illumination (LL) from approximately 15 months post hatch (MPH) (July 2000) in an enclosed tank system. Growth performance was recorded monthly along with observations of reproductive activity over the subsequent 2 years (up to July 2002). At both 2 and 3 years of age the entire population raised under SNP matured and spawned, during which time mean weight reduced by 13% and 24% respectively. No spawning individuals were recorded at 2 years of age in the LL population and only 18% were observed to spawn at 3. However, observations of both changes in gonadal morphology (observed via ultrasound scanning) and a suppression in growth rate at 2 years of age in the LL population alluded to a maturation “dummy run” regulated by an endogenous clock. Despite this phenomenon, the LL treatment realised a 39% and 43% improvement in wet weight following 1 and 2 years of exposure to LL respectively. When the diel cycle of plasma melatonin was compared between the treatments in February 2001 (23MPH) the SNP population displayed an A-profile diel rhythm ranging between 20 and 50 pg/ml while the LL treatment did not display any rhythm. In the second experiment of this work, two populations of cod (hatched, spring 2001) were reared in commercial open cage systems, one of which experienced continuous additional artificial illumination between July 2002 (15MPH) and October 2003 (30MPH) provided by four, 400W submerged lighting units. Growth and maturation were assessed in both populations throughout. In March 2003 (24MPH) it was apparent that spawning individuals were present in both the SNP and LL populations though a significantly lower number of spawning individuals in the LL treatment suggested that the peak in spawning activity was delayed by about 1 to 2 months. With both populations apparently maturing at 2 years of age, there was no significant difference in weight between the populations at the end of the trial. In comparison to experiments I and IV of this work, these results would suggest that in comparison to salmonids for example, Atlantic cod appear to have a heightened sensitivity to light allowing individuals to differentiate the ambient photoperiod signal from the application of continuous artificial light. In the third experiment, 6 populations of approximately 20 tagged individuals (hatched spring 1999) were maintained, from December 2000 to July 2002, under either SNP, LL or one of four, out of season “square wave” photoperiod regimes (repeating cycles with a 12 month period, consisting of a 6 month window of LL followed by six months of short day lengths [SD, 7L:17D] which had been staggered to start over a six month period). Each individual was monitored monthly for maturation status. Out of season “square wave” photoperiods were demonstrated to successfully entrain maturation and hence significantly alter the spawning profiles in these populations. Application of LL from December 2000 failed to inhibit maturation in the spring of 2001 and, in fact, advanced the spawning season by 1 month while those that experienced SD from the same date showed significant extension of the subsequent spawning season. Interestingly, the males maintained on LL throughout the experiment matured both in the spring of 2001 and one year later in the spring of 2002 while females under the same treatment only matured and spawned in 2001. In the fourth experiment, a total of 830 tagged individuals were raised either under SNP or one of 7 photoperiod treatments, consisting of 5 groups transferred from SNP to LL at 3 monthly intervals between 6 and 18 MPH where they remained and a further two groups maintained on LL from 6 to 15MPH and 6 to 21 MPH respectively before being returned to SNP. Both the gonadic and somatic axes were monitored at the physiological and endocrinological level at three monthly intervals from 6 to 27 MPH. The results demonstrated that it is the falling autumnal photoperiod signal after the summer solstice, more specifically after October, that is responsible for recruiting individuals to enter the sexual maturation cycle. Furthermore, in all treatments where this signal was masked i.e. those which experienced LL starting at or prior to 15MPH, except for some restricted spermatogenic activity in the males testis observed at 27MPH, there was no significant reproductive activity and growth was improved by up to 60% at 27 MPH. While providing evidence for direct photic stimulation of somatic growth, the growth results were also correlated with the measurement of plasma IGF-I and demonstrated its potential as a tool to assess growth rates in the species. Plasma melatonin measured at 15MPH, as in experiment I, was suppressed in all populations which were under LL photoperiods. By identifying the photoperiod “window of opportunity” which recruits individuals into the sexual maturation cycle, this work was able to conclude that the application of LL from the summer solstice prior to maturation is the most efficient photoperiod strategy to be adopted by the aquaculture industry to realise maximum growth potential from their cultured stocks.

Tez (Tıpta Uzmanlık) - Süleyman Demirel Üniversitesi, Tıp Fakültesi, Çocuk Sağlığı ve Hastalıkları Anabilim Dalı, 2006. / Bibliyografya var.

Thesis (doctoral)--University, Nijmegen, 2004. / Includes bibliographical references (p. 335-348).

Thesis (doctoral)--University, Nijmegen, 2004. / Includes bibliographical references (p. 335-348).

Thesis (Ph. D.)--Illinois State University, 1998. / Title from title page screen, viewed July 14, 2006. Dissertation Committee: Patricia A. Jarvis (chair), Deborah Gentry, Matthew Hesson-McInnis, Connie B. Horton, Margaret Nauta. Includes bibliographical references (leaves 82-93) and abstract. Also available in print.

Made available in DSpace on 2014-06-11T19:32:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-09-04Bitstream added on 2014-06-13T18:44:42Z : No. of bitstreams: 1 ortiz_js_dr_botfmvz.pdf: 233113 bytes, checksum: e2f5b280eca34f04cda10253a62b2d41 (MD5) / Universidade Estadual Paulista (UNESP) / O experimento foi desenvolvido no setor de Ovinocultura da Universidade de Marília com o objetivo de avaliar os efeitos dos níveis de suplementação alimentar com ração contendo 25% de PB e 3,18 Mcal EM/kg/MS para cordeiras criadas em pastagem com comedouro privativo sobre o peso e desempenho em distintas idades, bem como o inicio da puberdade e desempenho reprodutivo. Foram utilizadas 21 cordeiras Suffolk oriundas de parto simples, divididas em 3 lotes experimentais, sem e com suplementação, alimentadas do nascimento ao desmame em comedouros privativos com 2 níveis de ingestão de concentrado (300 e 600 g/dia) fornecido uma vez ao dia com o registro das sobras diárias. As cordeiras foram identificadas, pesadas ao nascimento e a cada 30 dias, permanecendo com suas mães até o desmame, pré-estabelecido em 60 dias. Não houve diferenças significativas para peso e ganho médio de peso diário aos 30 dias de idade, demonstrando que os níveis de ingestão não influenciaram os parâmetros analisados. O peso e ganho médio de peso diário foram influenciados pelo nível de suplementação alimentar. O lote com consumo de 600 gramas mostrou desempenho superior aos outros dois lotes aos 60 e 120 dias de idade. Para os lotes de 300 gramas e sem suplementação não houve diferença para os parâmetros analisados. A disponibilidade de 600 gramas diários de concentrado contendo 25% de PB e 3,18 Mcal de EM/kg/MS para as cordeiras até o desmame promoveu maior ganho médio de peso diário aos 60 e 120 dias de vida e melhor desempenho reprodutivo no 2º ano de cobertura. / The experiment was developed in the Sheep Production Department at University of Marília, wich aim was to evaluate the effects of the levels of the food supplies (without supplies, 300, 600 g of concentrate/day) with concentrate containing 25% of CP and 3,18 Mcal ME/kg/DM for females lambs raised in pasture with creep feeding about weight and acting in different ages, as well as the beginning of puberty and reproductive performance. The subjects were 21 female lambs Suffolk breed proceeding from simple birth which were divided into 3 experiment lots, fed from birth up to weaning in creep feeding with 2 levels of ingestion of concentrated (without supplied, 300 and 600 g/concentrate/day) given once a day by recording daily leftovers. The female lambs were identified weighed soon after birth and then, weighed every 30 days, remaining with their mothers up to weaning, pre established for 60 days. There was no significant difference for weight and medium gain of weight daily at 30 days of age, showing that the levels of ingestion did not influence the analyzed parameters. The weight and medium gain of daily weight were influenced for the level of food supplied, the lot consuming of 600 g showed performance greater than the other 2 lots at 60 and 120 days of age. For the lots of 300 g and without supplied there was no significant differences for the analyzed parameters. The availability of 600 g concentrated daily containing 25% of CP and 3,18 Mcal of ME/kg/DM for the female lambs up to weaning resulted in higher medium gain of weight daily at age of 60 and 120 days, as well as better reproductive performance in the 2º year of animal copulation.