Browsing by Subject "catecholamine"

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    Visual evoked potentials in pregnancy
    (1999) Yilmaz H.; Erkin E.F.; Mavioglu H.; Sungurtekin Ü.
    Pregnancy is a period when the estrogen/progesterone ratio rises considerably because of the passage of estrogen from the placenta. These changes in the level of estrogen during pregnancy increase the sensitivity of the central nervous system to cathecholamines. As a result, the sensitivity of the receptors in both the visual cortex and the inner plexiform layer of the retina to dopamine increases, and transmission in the optic pathways becomes faster. Inspired by this knowledge, we studied monocular pattern-reversal visual evoked potentials (PRVEPs) in both eyes of 30 pregnant women in the first trimester and 30 healthy nonpregnant women in the reproductive age. Mean P100 latency of pregnant women was significantly shorter than mean P100 latency of nonpregnant women (p<0.001). Mean P100 amplitude values were higher in pregnant women, although not statistically significant (p>0.05). Plasma estrogen and progesterone levels of pregnant women showed a negative correlation with PRVEP latencies, but a positive correlation with PRVEP amplitudes. In conclusion, this study supports the impression that changes in the levels of sex steroids affect the formation of PRVEPs by their actions on the central nervous system. The increase in estrogen during pregnancy seems to facilitate neural transmission in the optic pathways. Rise in the estrogen-progesterone level might be responsible for the shorter PRVEPs latencies in pregnant women.
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    The effect of gravity on the living organisms; [Yerçekimi deǧişikliklerinin canlilar üzerine etkileri: Mikroyerçekiminde ne ofmaktadir?]
    (2000) Varol T.
    The terrestrial animals are continuously under the effect of gravity. Gravity plays a role as an environmental factor, which determinates the process of intrauterine and postnatal development starting from fertilisation to every stage of life. The effect of gravity on the living organisms has become more important since space travelling with human and the possibility of colonisation in the space. There is great research on the effect of microgravity as an altered environmental factor in the space and in the planet which has smaller mass than earth. The progressive decreased bone mass occurs in the microgravity environment. This space osteoporosis which is similar to postmenopausal osteoporosis associates especially in the sponges part of weight bearing bones. It has been explained by the sensitivity of the osteoblast against the gravity and has been shown by the studies, which the number and the function of these cells were decreased in the microgravity environment. Rapid skeletal muscle atrophy and decrease of the neuronal activation in the CNS can be seen in the microgravity environment. There is also clear decrease of the number of T lymphocyte in microgravity conditions but it has not yet shown that this is a dangerous risk for human health. Other clinical symptoms like moderate hypothyroidism, decrease of insulin sensitivity, anaemia due to decrease of the erithropoietin levels in this conditions are still remains unclear, however, it seems that they are originated from the decrease of mobility and the decrease of energy requirement. In contrast, there is increase of cathecholamine activity that seems parodoxal. The negative effect of microgravity on the fertilisation and embryogenesis has not been shown yet and it does not effect lactation and maternal behaviour. Microgravity results in changes in the vestibular otolith organs and in the processing of inputs from otolith receptors and in alterations in the gain of vestibular influences on cardiovascular control which may produce orthostatic hypotension. The results of studies in the simulation of microgravity in the world and/or in the space laboratory shows that locomotor system, vestibular system and endocrine system are more effected by the microgravity environment. Although, these studies are still far away from the clear answers of the scientific questions for this matter but the life in microgravity and the possibility of alternative treatment using microgravity are not impossible and not a dream.
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    Hypertrophic cardiomyopathy: Pathological features and molecular pathogenesis
    (2004) Çam F.S.; Cüray M.
    Hypertrophic cardiomyopathy (HCM) is a heterogeneous genetic cardiac disorder with various genotypic and phenotypic manifestations, and is often a diagnostic challenge. Although more than forty years have passed since the first description of HCM, a variety of mutations in genes encoding sarcomeric proteins, that cause the disease have been defined by laboratory and clinical studies over the past few years. The fact that HCM is the most common cause of sudden death in young competitive athletes and that it is actually an important cause of morbidity and mortality in people of all ages, has made the researchers to concentrate more on the molecular basis and treatment strategies of the disease. This study aims to summarize both pathological features and rapidly evolving molecular genetics of HCM, and so to understand this not infrequently seen, complex disorder better.