首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
Due to the risks to the foetus with invasive prenatal diagnosis, non-invasive prenatal diagnosis (NIPD) is gaining tremendous interest but no reliable method that can be widely used has been developed to date. Manipulation of foetal cells and foetal cell-free genetic material in the maternal blood are two promising approaches being researched. The manipulation of foetal cells in the maternal circulation is more popular as it can provide complete genetic information of the foetus particularly the diagnosis of aneuploidies. However, the foetal cell numbers in the maternal circulation are small and their enrichment and ex vivo culture remain two major challenges for NIPD. Primitive foetal erythroblasts (pFEs) have been considered as a good potential candidate for early first trimester NIPD but their nature, properties and manipulation to provide adequate cell numbers remain a challenging task and several approaches need to be meticulously evaluated. In this review we describe the current status of NIPD and suggest some novel approaches in manipulating pFEs for future clinical application of NIPD. These novel approaches include (1) understanding the pFE enucleation process, (2) enriching pFE numbers by individual pick-up of pFEs from maternal blood using micromanipulation and microdroplet culture, (3) expansion of pFEs using mitogens and (4) decondensation of the pFE nucleus with histone deacetylase (HDAC) inhibitors followed by reprogramming using gene delivery protocols with/without small reprogramming molecules to improve reprogrammed pFE proliferation rates for successful NIPD.  相似文献   

3.
The morphogenesis of the foetal membranes of the African cane rat (Thryonomys swinderianus, Temminck) was studied and compared with that of the caviomorphs from South America. Like the guinea pig and chinchilla, implantation in the cane rat is interstitial, amniogenesis is by cavitation, there is very early and complete inversion of yolk sac endoderm, there is a well-developed subplacenta which persists throughout gestation, and the interhaemal membrane is haemomonochorial in nature. The phylogenetic significance of these findings are discussed in the light of long geographical and temporal separation between the continents.  相似文献   

4.
The aim of this study is to determine the effects of early and mid-gestation nutrient restriction on maternal metabolites and foetal growth. Primiparous Angus cows were synchronized and inseminated with semen from one sire. Dietary treatments were: control to gain 1 kg/week (CON) or 0.55% maintenance energy and CP requirements (nutrient restricted; NR). A subset of dams was fed NR (n=8) or CON (n=8) from days 30 to 110 of gestation. Another group was fed CON (n=8), days 30 to 190; NR (n=7), days 30 to 110 followed by CON days 110 to 190; or CON, (n=7) days 30 to 110 followed by NR days 110 to 190. Cows were harvested at days 110 or 190 of gestation, when foetal measurements and samples were collected. Cows that were NR during days 30 to 110 or 110 to 190 of gestation lost significant BW and body condition score (P<0.001), this was associated with reduced plasma glucose during NR (P<0.002). Foetal weights, empty foetal weights, abdominal and thoracic circumferences were all reduced (P<0.03) in day 110 NR animals. Foetal perirenal adipose as a percentage of empty foetal weight was increased (P=0.01) in NR day 110 female foetuses compared with CON foetus. Maternal serum triglycerides at day 110 of gestation were decreased (P<0.05) in NR dams, whereas foetal serum triglycerides were increased (P<0.05) in response to maternal NR. Foetal weights tended to be reduced (P=0.08) in NR/CON and CON/NR v. CON/CON cattle at day 190 of gestation. Empty foetal weights, abdominal and thoracic circumferences were reduced (P⩽0.03) in NR/CON and CON/NR v. CON/CON cattle. Brain weight as a percentage of empty foetal weight was increased (P<0.001) in NR/CON and CON/NR v. CON/CON cattle. Foetal perirenal adipose as a percentage of empty foetal weight was increased (P=0.003) in NR/CON and CON/NR v. CON/CON cattle. Maternal serum triglycerides at day 190 of gestation were decreased (P<0.05) in association with maternal NR. Foetal serum triglycerides at day 190 of gestation were increased (P<0.05) in response to maternal NR during early gestation but decreased by NR in mid gestation compared with CON foetuses. The data show that maternal nutrient restriction during early or mid-gestation cause’s asymmetrical foetal growth restriction, regardless if the restriction is preceded or followed by a period of non-restriction.  相似文献   

5.
Recent animal research suggests that it may soon be possible to support the human fetus in an artificial uterine environment for part of a pregnancy. A technique of extending gestation in this way (“ectogestation”) could be offered to parents of extremely premature infants (EPIs) to improve outcomes for their child. The use of artificial uteruses for ectogestation could generate ethical questions because of the technology’s potential impact on the point of “viability”—loosely defined as the stage of pregnancy beyond which the fetus may survive external to the womb. Several medical decisions during the perinatal period are based on the gestation at which infants are considered viable, for example decisions about newborn resuscitation and abortion, and ectogestation has the potential to impact on these. Despite these possible implications, there is little existing evidence or analysis of how this technology would affect medical practice. In this paper, we combine empirical data with ethical analysis. We report a survey of 91 practicing Australian obstetricians and neonatologists; we aimed to assess their conceptual understanding of “viability,” and what ethical consequences they envisage arising from improved survival of EPIs. We also assess what the ethical implications of extending gestation should be for newborn and obstetric care. We analyze the concept of viability and argue that while ectogestation might have implications for the permissibility of neonatal life-prolonging treatment at extremely early gestation, it should not necessarily have implications for abortion policy. We compare our ethical findings with the results of the survey.  相似文献   

6.
The morphogenesis of the foetal membranes and placenta of the root-rat Tachyoryctes splendens was studied by light microscopy. Implantation of the blastocyst is antimesometrial. The mode of implantation is secondary interstitial and the decidual reaction is similar to that in other rodents. Amniogenesis is by cavitation with a temporary open epamniotic cavity. Inversion of the yolk sac is complete but the disappearance of the parietal segment occurs relatively late. With the breakdown of both the decidua capsularis and parietalis, the yolk sac wall near the margins of the placenta becomes bathed in a pool of maternal blood and tissue debris resembling the haemophagous organ. The yolk sac villi are well vascularized. The allantoic cavity is persistent up to the limb bud stage. The definitive placenta is haemochorial and shows conspicuous endodermal sinuses or placental pits.  相似文献   

7.
The effects of l-arginine on porcine foetal development and myogenesis were determined. Twenty Swiss Large White gilts were randomly allocated to either the control (C) or l-arginine treatment (A). In addition to the standard gestation diet, A-sows received 26 g l-arginine daily from days 14 to 28 of gestation. At day 75 of pregnancy, sows were sacrificed and the number and weight of foetuses were recorded. From each litter, the lightest, heaviest and the ones with an average foetal weight (FtW) were selected. Primary (P), secondary (S) and total myofiber number as well as S/P ratio were determined in the semitendinosus (ST) and rhomboideus (RH) muscles. In A-sows, the number of viable foetuses (13.0 v. 9.3) and total FtW (4925 v. 3729 g) was greater (P ⩽ 0.04) than in C-sows. Compared to C-sow foetuses, the ST of A-sow foetuses had 7% more (17 699 v. 16 477; P = 0.04) P myofibers and the S/P ratio in both muscles was lower (ST = 20.3 v. 21.5; RH = 24.1 v. 27.1; P ⩽ 0.07). Regardless of the maternal diet, the S myofiber number and the S/P ratio in both muscles were greater (P ⩽ 0.01) in foetuses with a high FtW compared to low FtW. These data suggest that l-arginine supplemented to gilts during early gestation enhanced foetal survival and in the ST positively affected the primary phase of myofiber formation.  相似文献   

8.
TOLGA GUVEN  GURKAN SERT 《Bioethics》2010,24(3):127-133
Advance directives are not a part of the healthcare service in Turkey. This may be related with the fact that paternalism is common among the healthcare professionals in the country, and patients are not yet integrated in the decision‐making process adequately. However, starting from the enactment of the Regulation of Patient Rights in 1998, this situation started to change. While the paternalist tradition still appears to be strong in Turkey, the Ministry of Health has been taking concrete measures in the recent years to ensure that patient rights are implemented in healthcare practice. Therefore, Turkey now seems to be in a transitional period where a move towards a more patient‐autonomy centred approach is being supported by the regulatory authorities, as well as the academic circles and the public at large. In the light of this background, this paper aims to examine the potential benefits of advance directives, particularly with regard to their possible effect in the clinical decision‐making process of Turkey's context. It will be argued that advance directives, if correctly understood and implemented in the right settings, may be beneficial, particularly for improving communication between patients and healthcare professionals and for implementing of the right to refuse treatment.  相似文献   

9.
In recent years, there has been growing interest in estimating the degree of heating caused by the diagnostic ultrasound in clinical practice. Both theoretical and experimental methods have been suggested for estimating the heating potential, or thermal hazard, of diagnostic ultrasound. Aim of this study was to evaluate in vivo effects of ultrasound exposure of variable duration (from 10 up to 20 min) with commercially available imaging systems commonly used for diagnostic imaging. Numerical results related to the thermal effect are obtained by simulation program based on B-mode (scanning) and Doppler (non-scanning). To investigate the biological effects of the ultrasound exposure to the brain and liver tissues, the antioxidant enzyme activity and thiobarbituric acid reactive substances (TBARS) of the tissues were evaluated. In liver tissue, as a lipid peroxidation index, TBARS levels very significantly increase in Doppler group compared to control. However, in B-mode, TBARS levels are the same with the control group. Use of B-mode in foetal tissue is more reliable than Doppler mode because temperature rise is very small compared to the Doppler mode. On the other hand, the antioxidant enzyme activities tend to increase in B-mode and Doppler groups compared to the control group as a defensive mechanism. In the brain tissue, lipid peroxidation is increased slightly in B-mode compared to the control group. This situation is related to the molecular structure of the brain tissue because of its high lipid concentration. In brain tissue, the antioxidant enzyme activities and lipid peroxidation were significantly increased, such as liver tissue in Doppler groups. Doppler ultrasound may produce harmful effects in rat foetus liver and brain tissues as a result of the high temperature rises.  相似文献   

10.
Minor disulfide-bonded collagen (previously termed X1-X7 and now called type IX collagen) was isolated from foetal calf cartilage after pepsin treatment. At least three native fractions, containing, respectively, the X1X2X3, X4, and X5X6X7 chains, were separated; and from further biochemical and physicochemical experiments (differential scanning calorimetry, electrical birefringence, rotary shadowing), we propose a tentative model for their organization within a parent molecule. X1 and X2 are molecules composed of three chains of apparent Mr 62,000 and 50,000 linked by interchain disulfide bonds and containing pepsin-sensitive regions. The cleavage of at least three of these sites, present within X2, gives rise to the X3 and X5X6X7 fractions composed of molecules 80-100 nm and 40-55 nm in length, respectively. The X5X6X7 fraction is not digested by pepsin at 30 degrees C owing to its high thermal stability (certainly explained by its high hydroxyproline + proline content). This organization is in good accordance with that proposed for chicken cartilage type IX collagen; differences could only exist in the number and (or) the location of the pepsin-sensitive sites.  相似文献   

11.
The prediction from sex ratio theory that natural selection on sexually dimorphic mammals should favour an excess of male offspring only when mothers are in good condition, has been tested extensively but with little consistency in results. Although recent studies have shown that environmental variations may cause some of the discrepancy, there have also been reports of contrasting sex ratios under similar environmental settings. Here it is suggested that variation in timing of environmental stress and sex-specific differences in foetal growth pattern in relation to maternal condition, may explain such seeming contradictions in sex ratio variation of polygynous mammals.  相似文献   

12.
A considerable amount of recent medical research focuses on factors involving patient satisfaction. This study attempts to examine the role of autonomy in the gynecologist-patient relationship as it relates to patient satisfaction. Fifty-five patients at a women’s clinic completed measures assessing autonomy preference (API) before the medical visit and patient-perceived autonomy support (HCCQ) and patient satisfaction (MISS) after the visit. Analyses revealed patients prefer a more equal level of decision making with their doctor (a medium level of autonomy) when asked general questions about medical decisions but preferred less autonomy when presented with actual scenarios. Results show a significant relationship between scenario-based autonomy preference level and visit satisfaction for both satisfaction measures. A significant relationship between perceived autonomy support and visit satisfaction was also found for both satisfaction measures. The findings of this study suggest autonomy is important to the gynecologist-patient relationship and worthy of future study.  相似文献   

13.
Summary Haem proteins of different molecular sizes were perfused into the foetal circulation of the guinea-pig placenta to study the permeability of the foetal endothelium.The smallest molecules tested, microperoxidase (ae 1.0 nm) and cytochrome C (ae 1.5 nm), readily penetrated the endothelium; tracer-reaction product was found in the subendothelial space of the capillaries. However, there was no uptake of these two tracers into the syncytiotrophoblast layer of the placenta. An intermediate-sized molecule, myoglobin (ae 1.7 nm), produced only a weak reaction product in the subendothelial space even when perfused at high concentration. The largest molecule tested, haemoglobin (ae 2.8 nm), did not penetrate the foetal endothelium at any of the concentrations employed.The foetal capillary endothelium thus provided a barrier to protein penetration from the foetal circulation, dependent on molecular size. There was evidence that the site of this barrier was located in the lateral intercellular spaces between the endothelial cells.The syncytiotrophoblast of this haemomonochorial placenta provided an almost absolute barrier to protein penetration from the foetal circulation. As other workers have described maternal-to-foetal transmission of proteins across this layer in the guinea-pig, a working hypothesis of the role of endothelium and syncytiotrophoblast in maternal/foetal protein exchange is discussed.  相似文献   

14.
Intracerebral haemorrhage (ICH) can lead to secondary insults and severe neurological deficits. Transplantation of neural stem cells (NSCs) was suggested as an alternative to improve ICH-induced neurological dysfunction. The present study aimed at investigating the therapeutic role and long-term survival of foetal NSCs and potential role of foetal NSCs-produced factors in ICH. Our results demonstrated that foetal NSCs could differentiate into neural axons and dendrites and astrocytes in both in vitro and in vivo conditions, demonstrated by positive double or triple staining with Hoechst, neuronal specific nuclear protein, neurofilaments and glial fibrillary acidic protein. Intracerebral transplantation of foetal NSCs 3 days after ICH induction by intrastriatal administration of bacterial collagenase could improve the functional performance in the limb-placing test and shorten the duration of the recovery from ICH-induced neural disorders. The foetal NSCs may also produce neurotrophic and/or neuroprotective factors during culture, because the culture medium alone could partially improve functional performance. Thus, our data suggest that the foetal NSCs may be one of the therapeutic candidates for ICH.  相似文献   

15.
Self‐admission to inpatient treatment is a novel approach that aims to increase agency and autonomy for patients with severe psychiatric illness and a history of high utilization of inpatient care. By focusing on brief, preventive hospital admissions in times of increased risk of relapse, self‐admission seeks to reduce the need for prolonged episodes of inpatient treatment. Participants are generally satisfied with the model, which is not surprising given that self‐admission programs allocate a scarce resource—hospital beds—to a select group. However, the patients targeted by these programs are not necessarily those in most need of hospital admission, which may compromise the commonly accepted ‘principle of need’ in allocation of public healthcare resources. In light of the current lack of consistent evidence of the usefulness and cost‐effectiveness of the model, several aspects need to be further studied in order to guide any large‐scale implementation of self‐admission in psychiatry.  相似文献   

16.
17.
There are three lines of argument in defence of coercive treatment of patients with mental disorders: arguments regarding (1) societal interests to protect others, (2) the patients' own health interests, and (3) patient autonomy. In this paper, we analyse these arguments in relation to an idealized case, where a person with a mental disorder claims not to want medical treatment for religious reasons. We also discuss who should decide what in situations where patients with mental disorders deny treatment on seemingly rational grounds. We conclude that, in principle, coercive treatment cannot be defended for the sake of protecting others. While coercive actions can be acceptable in order to protect close family and others, medical treatment is not justified for such reasons but should be given only in the interest of patients. Coercive treatment may be required in order to promote the patient's health interests, but health interests have to waive if they go against the autonomous interests of the patient. We argue that non-autonomous patients can have reasons, rooted in their deeply-set values, to renounce compulsory institutional treatment, and that such reasons should be respected unless it can be assumed that their new predicaments have caused them to change their views.  相似文献   

18.
19.
Left ventricular torsion is caused by shortening and relaxation of the helical fibres in the myocardium, and is thought to be an optimal configuration for minimizing myocardial tissue strains. Characteristics of torsional motion has also been proposed to be markers for cardiac dysfunction. However, its effects on fluid and energy dynamics in the left ventricle have not been comprehensively investigated. To investigate this, we performed image-based flow simulations on five healthy adult porcine and two healthy human foetal left ventricles (representing two different length scales) at different degrees of torsional motions. In the adult porcine ventricles, cardiac features such as papillary muscles and mitral valves, and cardiac conditions such as myocardial infarctions, were also included to investigate the effect of twist. The results showed that, for all conditions investigated, ventricular torsional motion caused minimal changes to flow patterns, and consistently accounted for less than 2% of the energy losses, wall shear stresses, and ejection momentum energy. In contrast, physiological characteristics such as chamber size, stroke volume and heart rate had a much greater influence on flow patterns and energy dynamics. The results thus suggested that it might not be necessary to model the torsional motion to study the flow and energy dynamics in left ventricles.  相似文献   

20.
Braude H  Kimmelman J 《Bioethics》2012,26(3):149-156
Over the past several decades the 'affective revolution' in cognitive psychology has emphasized the critical role affect and emotion play in human decision-making. Drawing on this affective literature, various commentators have recently proposed strategies for managing therapeutic expectation that use contextual, symbolic, or emotive interventions in the consent process to convey information or enhance comprehension. In this paper, we examine whether affective consent interventions that target affect and emotion can be reconciled with widely accepted standards for autonomous action. More specifically, the ethics of affective consent interventions is assessed in terms of key elements of autonomy, comprehension and voluntariness. While there may appear to be a moral obligation to manage the affective environment to ensure valid informed consent, in circumstances where volunteers may be prone to problematic therapeutic expectancy, this moral obligation needs to be weighed against the potential risks of human instrumentalization. At this point in time we do not have enough information to be able to justify clearly the programmatic manipulation of human subjects' affective states. The lack of knowledge about affective interventions requires corresponding caution in its ethical justification.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号