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The Journal of Pediatrics Jul 2017
Topics: Physicians; Sexual Maturation
PubMed: 28648279
DOI: 10.1016/j.jpeds.2017.05.013 -
Journal of Environmental Radioactivity Jan 2019There are still considerable gaps in knowledge regarding the biological effects of chronic ionising radiation exposure in amphibians. To fill these gaps, Tohoku hynobiid...
There are still considerable gaps in knowledge regarding the biological effects of chronic ionising radiation exposure in amphibians. To fill these gaps, Tohoku hynobiid salamanders, Hynobius lichenatus (Amphibia, Caudata), were chronically irradiated with Cs γ-rays from embryonic to adult stages over 1954 days, and the effects on their growth and sexual maturation were examined under laboratory conditions. Irradiation at a dose rate of 33 μGy h had some stimulatory effects on growth (body weight increase) of H. lichenatus, while growth was temporarily or permanently suppressed at 150 or 510 μGy h, respectively. On day 1802, secondary sexual characteristics (a tubercle at the anterior angle of the cloacal vent for males and ovisac development for females) were observed in 91% of the salamanders irradiated at 33 μGy h, and in a similar percentage of non-irradiated controls. At 150 and 510 μGy h, secondary sexual characteristics were not observed in any individuals. These results suggest that the derived consideration reference level (DCRL) of the International Commission on Radiological Protection (ICRP) for Reference Frog, i.e. 40-400 μGy h, is applicable for the protection of H. lichenatus, and that growth and sexual maturation of this salamander may not have been adversely affected even in the most severely contaminated area in Fukushima, where the highest dose rate to salamanders was estimated to be 50 μGy h. However, observations in the contaminated area are required to confirm this conclusion, considering the possible confounding factors which may make this salamander more sensitive to radiation in the natural environment than under laboratory conditions.
Topics: Animals; Gamma Rays; Sexual Maturation; Urodela
PubMed: 30423483
DOI: 10.1016/j.jenvrad.2018.10.017 -
Neuroendocrinology 2014All reproductively competent adults have gone through puberty. While key genes and signaling pathways that lead to the onset of sexual maturation are known, the... (Review)
Review
All reproductively competent adults have gone through puberty. While key genes and signaling pathways that lead to the onset of sexual maturation are known, the molecular mechanisms that determine when an individual enters puberty are only beginning to be understood. Both genetic and environmental factors determine the timing of puberty. New advances in understanding how environmentally sensitive, yet highly heritable developmental processes are regulated have come from the field of epigenetics. Of note, studies investigating the epigenetic control of the onset of puberty suggest that epigenetic repression of key inhibitory loci may play a fundamental role in the initiation of puberty. Current technologies that not only read out the DNA sequence, but also determine how the DNA is modified in response to the environment, promise new insight into how puberty is regulated, including the identification and understanding of gene regulatory networks that control the biological pathways affecting pubertal timing. Here we review the findings to date and discuss how epigenetic investigation can further our understanding of this fundamental aspect of human development.
Topics: Animals; Epigenesis, Genetic; Epigenomics; Humans; Puberty; Sexual Maturation
PubMed: 24718029
DOI: 10.1159/000362559 -
General and Comparative Endocrinology Apr 2017Interactions between the immune and endocrine systems are not well studied in marsupials and monotremes. One exception to this is the phenomenon of semelparity, which is... (Review)
Review
Interactions between the immune and endocrine systems are not well studied in marsupials and monotremes. One exception to this is the phenomenon of semelparity, which is well covered in the literature as this is an unusual reproductive strategy amongst mammals and is only observed in some dasyurid and didelphid marsupials. Thymus involution provides a direct link between the endocrine and immune systems and warrants further study in marsupials and monotremes. The thymus is a primary immune tissue which is essential for overall immune function. Whilst the organ is large in juvenile animals, it begins to involute around puberty due to the suppressive effects of sex steroids. Thymus involution has a significant effect on the immune system, as it signals the onset of immune aging and decline in function. The output of naïve T lymphocytes by the thymus decreases, increasing susceptibility of aged individuals to infection and cancers. Understanding the links between the immune and endocrine system in marsupials and monotremes may shed light on diseases such as devil facial tumour disease (DFTD) which threatens the future of the Tasmanian devil. We hypothesise that changes in sex hormones around puberty may drive changes in the immune system, such as thymus involution, which may make devils more susceptible to DFTD as they age. In addition, the Schwann cell origin of DFTD may enable tumours to respond to sex hormones, as occurs in similar cancers in humans.
Topics: Animals; Humans; Marsupialia; Monotremata; Sexual Maturation
PubMed: 28132863
DOI: 10.1016/j.ygcen.2017.01.026 -
Endocrine Practice : Official Journal... Oct 2008To evaluate the reliability of a self-assessment tool as a surrogate means for estimating phase of sexual maturation in children and adolescents with diabetes mellitus.
OBJECTIVE
To evaluate the reliability of a self-assessment tool as a surrogate means for estimating phase of sexual maturation in children and adolescents with diabetes mellitus.
METHODS
Children and adolescents between 8 and 16 years of age with the diagnosis of type 1 or type 2 diabetes mellitus were recruited from the pediatric endocrinology clinic at a children's hospital. Participants were given a series of gender-appropriate drawings representing the 5 Tanner stages of sexual maturation for genital development in boys and breast and genital development in girls and asked to select the illustration that best represented their current maturity stage. The self-assessments were compared with physical examination findings by pediatric endocrinologists. Demographic and clinical data including age, race, hemoglobin A1c level, type of diabetes, and body mass index were also collected. Agreement rates between participants and physician assessment were compared. A level of agreement greater than 80% and a kappa coefficient greater than 0.61 were considered substantial.
RESULTS
Eighty-seven children and adolescents completed the study. Agreement rates for girls were greater than 80%. Agreement rates for boys were 76%. All kappa coefficients for boys and girls were greater than 0.61, corresponding to good agreement. However, peripubertal participants overestimated their sexual maturity rating almost half the time. The role of age, metabolic control (as measured by hemoglobin A1c), race, type of diabetes, and body mass index did not influence a participant's ability to accurately assess sexual maturity.
CONCLUSION
While useful in mid- to late-pubertal youth with diabetes, this self-assessment tool does not appear to be helpful in identifying the early stages of puberty.
Topics: Adolescent; Child; Diabetes Mellitus; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Humans; Puberty; Self-Assessment; Sexual Maturation
PubMed: 18996811
DOI: 10.4158/EP.14.7.840 -
Animal Reproduction Science Nov 2015MicroRNAs (miRNAs) have been implicated in several cellular processes of reproductive tissues through post-transcriptional regulation of protein coding genes. The...
MicroRNAs (miRNAs) have been implicated in several cellular processes of reproductive tissues through post-transcriptional regulation of protein coding genes. The presence of miRNAs, their expression patterns and processing machinery genes in different stages of testicular and ovarian cellular development have demonstrated the potential role of miRNAs in testicular and ovarian physiology. The Chinese mitten crab (Eriocheir sinensis) is one of the most important aquaculture species in China and has high commercial value as a food source. The molecular mechanisms underlying testis development in these and other crustaceans, which migrate to a new habitat to breed, remain poorly understood. We focus on the gonad of E. sinensis and systematically examined the expression profile of miRNAs in testes during sexual maturation stages using the Illumina Solexa sequencing technology. We found that the microRNA transcriptome exhibited dynamic expression during crab testis development. Subsequent bioinformatic analysis on both conserved and 15 novel miRNAs illustrated that some miRNAs demonstrated a tissue-specific expression pattern and were associated with target genes involved in reproductive function. Our study illustrates how detailed profiling of miRNA expression during stages of sexual maturation and in different tissues can lead to elucidate the role of miRNAs in regulating the development and differentiation of reproductive organs.
Topics: Animals; Brachyura; Female; Gene Expression Profiling; High-Throughput Nucleotide Sequencing; Male; MicroRNAs; Sexual Maturation; Testis
PubMed: 26455894
DOI: 10.1016/j.anireprosci.2015.09.008 -
Orvosi Hetilap Nov 1958
Topics: Humans; Puberty; Puberty, Precocious; Sexual Maturation
PubMed: 13623199
DOI: No ID Found -
JAMA Sep 1982
Topics: Adolescent; Child; Female; Gonadotropin-Releasing Hormone; Humans; Male; Puberty; Sexual Maturation
PubMed: 7050424
DOI: 10.1001/jama.248.10.1157 -
Journal of Neuroendocrinology Aug 1998In many species, delayed sexual maturation occurs when metabolic conditions are not satisfactory. Recently, leptin was shown to be involved in the regulation of food...
In many species, delayed sexual maturation occurs when metabolic conditions are not satisfactory. Recently, leptin was shown to be involved in the regulation of food intake and body mass. Furthermore, leptin administration was shown to advance sexual maturation in mice and to rescue sexual function in adverse metabolic conditions. We examined plasma leptin levels in female rats during development and evaluated the role of leptin on sexual maturation in rats subjected to food restriction. In normal rats, plasma leptin levels were low at day 24 of life, then steadily increased during the juvenile period, reaching 740+/-56 pg/ml at 40 days at time of vaginal opening (VO) and further increasing by day 60 (957+/-73 pg/ml). Food restriction initiated at day 25 strongly impaired this increase, in proportion to the severity of the restriction. With a daily food intake reduced to 7-8 g/day, that permanently prevented VO, plasma leptin levels were very low at day 53 (169+/-67 pg/ml). Following switch to ad libitum feeding, plasma leptin reached high levels within 2 days (1577+/-123 pg/ml), and VO occurred 4 days later. If the severe food restriction was maintained and a central infusion of leptin (10 microg/day) was initiated, a significant decrease in body weight compared with vehicle-infused controls was observed. In these conditions, VO occurred in eight out of the nine leptin-treated rats, representing induction of the process of sexual maturation confirmed by increases in ovarian and uterine weights. This induction of sexual maturation exclusively results from a central effect of leptin because no leak of the i.c.v. administered leptin to the general circulation was observed. These data suggest that the rising plasma levels of leptin in the prepubertal period represent a signal to the brain indicating that the young animal is metabolically ready to go through the process of sexual maturation.
Topics: Animals; Brain; Female; Food Deprivation; Infusion Pumps, Implantable; Leptin; Mice; Proteins; Rats; Rats, Sprague-Dawley; Sexual Maturation
PubMed: 9725715
DOI: 10.1046/j.1365-2826.1998.00247.x -
Journal of Theoretical Biology May 2018Ectothermic and endothermic vertebrates differ not only in their source of body temperature (environment vs. metabolism), but also in growth patterns, in timing of...
Ectothermic and endothermic vertebrates differ not only in their source of body temperature (environment vs. metabolism), but also in growth patterns, in timing of sexual maturation within life, and energy intake functions. Here, we present a mathematical model applicable to ectothermic and endothermic vertebrates. It is designed to test whether differences in the timing of sexual maturation within an animal's life (age at which sexual maturity is reached vs. longevity) together with its ontogenetic gain in body mass (growth curve) can predict the energy intake throughout the animal's life (food intake curve) and can explain differences in energy partitioning (between growth, reproduction, heat production and maintenance, with the latter subsuming any other additional task requiring energy) between ectothermic and endothermic vertebrates. With our model we calculated from the growth curves and ages at which species reached sexual maturity energy intake functions and energy partitioning for five ectothermic and seven endothermic vertebrate species. We show that our model produces energy intake patterns and distributions as observed in ectothermic and endothermic species. Our results comply consistently with some empirical studies that in endothermic species, like birds and mammals, energy is used for heat production instead of growth, and with a hypothesis on the evolution of endothermy in amniotes published by us before. Our model offers an explanation on known differences in absolute energy intake between ectothermic fish and reptiles and endothermic birds and mammals. From a mathematical perspective, the model comes in two equivalent formulations, a differential and an integral one. It is derived from a discrete level approach, and it is shown to be well-posed and to attain a unique solution for (almost) every parameter set. Numerically, the integral formulation of the model is considered as an inverse problem with unknown parameters that are estimated using a series of empirical data.
Topics: Animals; Body Mass Index; Body Temperature; Energy Intake; Growth; Models, Theoretical; Sexual Maturation; Thermogenesis; Vertebrates
PubMed: 29452173
DOI: 10.1016/j.jtbi.2018.02.007