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1.
Nanotechnology ; 34(50)2023 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-37748477

RESUMO

Two-dimensional (2D) p-n heterojunctions have attracted great attention due to their outstanding properties in electronic and optoelectronic devices, especially in photodetectors. Various types of heterojunctions have been constituted by mechanical exfoliation and stacking. However, achieving controlled growth of heterojunction structures remains a tremendous challenge. Here, we employed a two-step KI-assisted confined-space chemical vapor deposition method to prepare multilayer WSe2/SnS2p-n heterojunctions. Optical characterization results revealed that the prepared WSe2/SnS2vertical heterostructures have clear interfaces as well as vertical heterostructures. The electrical and optoelectronic properties were investigated by constructing the corresponding heterojunction devices, which exhibited good rectification characteristics and obtained a high detectivity of 7.85 × 1012Jones and a photoresponse of 227.3 A W-1under visible light irradiation, as well as a fast rise/fall time of 166/440µs. These remarkable performances are likely attributed to the ultra-low dark current generated in the depletion region at the junction and the high direct tunneling current during illumination. This work demonstrates the value of multilayer WSe2/SnS2heterojunctions for applications in high-performance photodetectors.

2.
Mol Hum Reprod ; 28(2)2022 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-35150275

RESUMO

Histone-to-protamine transition is an essential step in the generation of fully functional spermatozoa in various mammalian species. In human and mouse, one of the two protamine-encoding genes produces a precursor pre-protamine 2 (pre-PRM2) protein, which is then processed and assembled. Here, we design an original approach based on the generation of pre-PRM2-specific antibodies to visualize the unprocessed pre-PRM2 by microscopy, flow cytometry and immunoblotting. Using mouse models with characterized failures in histone-to-protamine replacement, we show that pre-PRM2 retention is tightly linked to impaired nucleosome disassembly. Additionally, in elongating/condensing spermatids, we observe that pre-PRM2 and transition protein are co-expressed spatiotemporally, and their physical interaction suggests that these proteins act simultaneously rather than successively during histone replacement. By using our anti-human pre-PRM2 antibody, we also measured pre-PRM2 retention rates in the spermatozoa from 49 men of a series of infertile couples undergoing ICSI, which shed new light on the debated relation between pre-PRM2 retention and sperm parameters. Finally, by monitoring 2-pronuclei embryo formation following ICSI, we evaluated the fertilization ability of the sperm in these 49 patients. Our results suggest that the extent of pre-PRM2 retention in sperm, rather than pre-PRM2 accumulation per se, is associated with fertilization failure. Hence, anti-pre-PRM2 antibodies are valuable tools that could be used in routine monitoring of sperm parameters in fertility clinics, as well as in experimental research programmes to better understand the obscure process of histone-to-protamine transition.


Assuntos
Histonas , Injeções de Esperma Intracitoplásmicas , Animais , Feminino , Histonas/metabolismo , Humanos , Masculino , Mamíferos , Camundongos , Protaminas/metabolismo , Espermatozoides/metabolismo
3.
Small ; 16(22): e2000420, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32350995

RESUMO

MoS2 , one of the most valued 2D materials beyond graphene, shows potential for future applications in postsilicon digital electronics and optoelectronics. However, achieving hole transport in MoS2 , which is dominated by electron transport, is always a challenge. Here, MoS2 transistors gated by electrolyte gel exhibit the characteristics of hole and electron transport, a high on/off ratio over 105 , and a low subthreshold swing below 50 mV per decade. Due to the electrolyte gel, the density of electrons and holes in the MoS2 channel reaches ≈9 × 1013 and 8.85 × 1013 cm-2 , respectively. The electrolyte gel-assisted MoS2 phototransistor exhibits adjustable positive and negative photoconductive effects. Additionally, the MoS2 p-n homojunction diode affected by electrolyte gel shows high performance and a rectification ratio over 107 . These results demonstrate that modifying the conductance of MoS2 through electrolyte gel has great potential in highly integrated electronics and optoelectronic photodetectors.

4.
J Assist Reprod Genet ; 35(5): 879-884, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29589293

RESUMO

PURPOSE: To evaluate the differences in implantation and pregnancy rates when embryo transfer occurs on D2 versus D3 in women with a low yield of fertilized oocytes. METHODS: A total of 156 IVF/ICSI cycles from 141 women at an academic fertility center were analyzed in a retrospective fashion. Women with a low number of fertilized oocytes (≤ 2 two pronuclei (2PN) stage zygotes) who had their fresh embryo transfer on D2 or D3 were included in the study. Positive pregnancy test per IVF cycle (PPT), clinical pregnancy rate (CPR), spontaneous abortion rate (SABR), and implantation rate (IMPR) were the main outcome measures assessed. Mann-Whitney U test and χ2 test were used as appropriate. A generalized linear mixed effect model adjusted for relevant covariates was conducted. P < 0.05 was considered significant. RESULTS: Patients having their embryo transfer on D2, when compared to those who had a D3 embryo transfer, experienced similar PPT [30.8 vs. 28.2%, respectively; adjusted OR (95%CI): 0.49 (0.16, 1.52)], CPR [26.9 vs. 25.6%, respectively; adjusted OR (95%CI): 0.44 (0.12, 1.67)], and IMPR [17.3 vs. 16.7%, respectively; adjusted ß (95%CI) - 5.6% (- 15.0, 3.9)]. CONCLUSION: Our findings suggest that transferring embryos on D2 versus D3 in women with a limited number of 2PN stage zygotes does not affect early pregnancy outcomes. These results indicate that there can be some flexibility in scheduling the day of transfer at the convenience of both the patient and the center.


Assuntos
Transferência Embrionária/métodos , Fertilização in vitro/métodos , Aborto Espontâneo , Adulto , Implantação do Embrião , Feminino , Humanos , Recuperação de Oócitos , Gravidez , Resultado da Gravidez , Taxa de Gravidez , Estudos Retrospectivos , Fatores de Tempo
5.
J Assist Reprod Genet ; 35(7): 1349-1356, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29704226

RESUMO

PURPOSE: Cleavage of the zygote during human reproduction is a key event of early embryonic development. The genetic events associated with idiopathic embryonic cleavage failure are not certain. Mutations in the tubulin beta 8 class VIII (TUBB8) gene have been reported to be associated with oocyte maturation, fertilization, and developmental arrest. Here, we aimed to assess the clinical and genetic characteristics of complete cleavage failure in fertilized eggs. METHODS: We have characterized a patient with a 9-year history of primary infertility in a non-consanguineous family from China. The patient presented complete cleavage failure in all two-pronuclear (2PN) fertilized oocytes after 2 cycles of in vitro fertilization (IVF). We performed Sanger sequencing of the TUBB8 gene in the patient, and further bioinformatics analysis to identify pathogenesis of gene. RESULTS: A novel homozygous mutation, c.322G > A (p.Glu108Lys), was detected, and this change was absent from 179 control subjects. Glutamic acid is highly conserved at this position, and replacement by lysine was predicted to be repelled by the α-tubulin positive region, disrupting the α-ß tubulin interaction. CONCLUSIONS: Our findings presented a homozygous mutation of TUBB8 associated with complete cleavage failure in fertilized eggs and provided new data for the genotype-phenotype of TUBB8-related diseases.


Assuntos
Fase de Clivagem do Zigoto/fisiologia , Desenvolvimento Embrionário/fisiologia , Mutação/genética , Oócitos/fisiologia , Tubulina (Proteína)/genética , Adulto , China , Feminino , Fertilização in vitro/métodos , Humanos , Infertilidade Feminina/genética , Zigoto/fisiologia
6.
Arch Gynecol Obstet ; 297(2): 529-537, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29230537

RESUMO

PURPOSE: The aim of this study was to accurately describe outcome differences (cryo-survival, pregnancy rate and live birth rate, both per ET and cumulatively), between the vitrification method and slow-freezing method of surplus 2PN oocytes in an IVF program. METHODS: In 2004, the freezing method for 2PN oocytes was changed from slow-cooling to vitrification. The data of 711 patients (timespan: 1/1999-7/2011; 410 vitrification and 301 slow-cooling events) undergoing a first IVF/ICSI cycles with freezing of 2PN oocytes were retrospectively analyzed. The outcome of one, the first, IVF cycle per patient was explored. The data were analyzed per freezing-thawing attempt as well as cumulatively per one complete IVF cycle, taking pregnancy occurrence after a fresh embryo transfer preceding the cryo-cycle(s) and other confounders (such as female age, elective vs. surplus 2PN cryopreservation) into account by means of exploratory regression analyses. RESULTS: In the vitrification and slow-cooling group, 756 and 376, respectively, attempts of thawing 2PN oocytes were recorded. Each attempt of thawing 2PN oocytes showed statistically significantly higher mean cryo-survival rates after vitrification (effect size approximately 30-40%, with vitrification cryo-survival consistently above 90% in all thawing attempts). Furthermore, the incidence of "zero survival" was lower after vitrification (0.5 vs. 7.3%, p < 0.01). It is estimated that the odds of achieving a live birth per one IVF cycle (fresh and frozen transfers combined) with vitrification of 2PN oocytes is increased approximately 1.4-fold (OR of 1.405, 95% CI 0.968-2.038; p = 0.07); however, statistical significance was not achieved due to sample size. Female age and elective cryopreservation of all 2PN oocytes without a fresh transfer (e.g., hyperresponders) were found to be negatively and positively, respectively, associated with the chance of achieving a live birth. CONCLUSIONS: The introduction of vitrification has a measurable impact on the efficacy of an IVF program. However, this effect is not large despite the impressively higher cryo-survival rates with vitrification. The "true" net efficacy effect of introducing 2PN vitrification in an IVF program will, in real life, be lower due to patients not having surplus 2PN oocytes available for freezing and later transfer.


Assuntos
Criopreservação/métodos , Transferência Embrionária/métodos , Resultado da Gravidez , Taxa de Gravidez , Vitrificação , Adulto , Coeficiente de Natalidade , Feminino , Fertilização in vitro , Congelamento , Humanos , Nascido Vivo/epidemiologia , Oócitos , Gravidez , Estudos Retrospectivos
7.
Reprod Biomed Online ; 31(6): 799-804, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26507280

RESUMO

Artificial oocyte activation (AOA) has been previously suggested as a means to overcome the problem of total fertilization failure, which affects about 1-3% of the intracytoplasmic sperm injection (ICSI) cycles. A preliminary study on the application of chemical AOA was conducted using A23187 Ca(2+) ionophore to improve embryonic development in four women with a history of complete fertilization arrest and inability to transit to cleavage stage during previous ICSI trials. Data indicated that activated oocytes resulted in better fertilization, embryonic development and clinical pregnancy in one of the four couples. Therefore, ICSI combined with AOA using Ca(2+) ionophore may be useful in selected patients with cleavage failure, and may help the zygotes to reach more advanced developmental stages.


Assuntos
Ionóforos de Cálcio/farmacologia , Fase de Clivagem do Zigoto/efeitos dos fármacos , Injeções de Esperma Intracitoplásmicas/métodos , Zigoto/efeitos dos fármacos , Adulto , Ionóforos de Cálcio/uso terapêutico , Fase de Clivagem do Zigoto/citologia , Feminino , Fertilização/efeitos dos fármacos , Humanos , Técnicas de Maturação in Vitro de Oócitos/métodos , Masculino , Oócitos/efeitos dos fármacos , Oócitos/fisiologia , Oogênese/efeitos dos fármacos , Projetos Piloto , Gravidez , Resultado do Tratamento , Adulto Jovem , Zigoto/citologia , Zigoto/fisiologia
8.
J Int Med Res ; 52(3): 3000605241233985, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38548469

RESUMO

OBJECTIVE: This study aimed to compare the pregnancy outcomes of Day 2 (D2) fresh embryo transfer and D3 fresh embryo transfer in women with only one zygote with two pronuclei (2PN). METHODS: Data on 432 in vitro fertilization-embryo transfer cycles with only one 2PN zygote from January 2016 to January 2022 were retrospectively collected. A total of 302 fresh embryo transfers on D2 (n = 193) and D3 (n = 109) were analyzed, and pregnancy outcomes were compared. RESULTS: The patients' characteristics were not different between D2 and D3 embryo transfer. There were no significant differences in the rates of clinical pregnancy, early abortion, or live birth between D2 and D3 embryo transfer. A multivariate logistic regression model controlling for age, the fertilization method, the number of oocytes harvested, and the number of high-quality embryos transferred showed that the live birth rate was similar between D2 and D3 embryo transfer. CONCLUSION: In in vitro fertilization-embryo transfer cycles with only one 2PN zygote, D2 fresh embryo transfer may provide similar pregnancy outcomes to those of D3 embryo transfer. D2 embryo transfer may be an option because of the risk of cycle cancellation due to the absence of viable embryos on D3.


Assuntos
Fertilização in vitro , Zigoto , Gravidez , Humanos , Feminino , Estudos Retrospectivos , Taxa de Gravidez , Fertilização in vitro/métodos , Transferência Embrionária/métodos
9.
Front Cell Dev Biol ; 11: 1095069, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36711030

RESUMO

Introduction: Cryopreservation of bipronuclear (2PN) stage zygotes is an integral part of IVF laboratory practice in countries with strict embryo culture legislation. Vitrification of zygotes is compatible with several strategies in infertility treatments holding a freeze-all indication and allows for effective workload management in settings with limited resources. Although it yields high survival rates and clinical outcomes, the ideal timing to commence vitrification of zygotes is elusive while it is empirically practiced in the window between 17 and 21 h post-insemination (hpi). We aimed to deduce the association between pregnancy rate and the time interval from insemination (IVF and ICSI) to vitrification to contribute to the standardization ofzygote cryopreservation. Methods: A retrospective analysis of data on vitrification timings and pregnancy outcomes collected between 2011 and 2019 was performed. All included women received an embryo transfer after warming of vitrified zygotes at the 2PN stage. Results: A total of 468 embryo transfers were included of which 182 (38.9%) resulted in pregnancy and 286 (61.1%) not. Vitrification was on average performed 18.74 ±0.63 hpi in the pregnant group and 18.62 ± 0.64 hpi in the non-pregnant group (OR 1.36, 95% CI 1.01; 1.83, p = 0.045). A multivariate analysis controlling for uterine pathologies, maternal age, AMH, the number of MII oocytes, previous history of pregnancy success, endometriosis, AFC, nicotine intake and male factor infertility showed no predictive value of vitrification timing on pregnancy rate. Three time intervals between insemination and vitrification were defined: 17:00 to 18:00 hpi (Group A), 18:01 to 19:00 hpi (Group B) and 19:01 to 21:00 hpi (Group C). Pregnancy occurred in 40/130 women (30.80%) in Group A, in 115/281 women (40.90%) in Group B and in 27/57 women (47.40%) in Group C. Univariate but not multivariate analysis showed a significantly higher pregnancy rate after the latest time interval between insemination and 2PN vitrification when compared to the earliest (Group C vs. A, OR 2.03, 95% CI 1.07; 3.84, p = 0.031). Discussion: These findings encourage further investigation on the impact of vitrification timing on clinical outcomes and hold the potential to standardize cryopreservation of zygotes from IVF/ICSI cycles to eventually improve the quality of long-term ART outcomes.

10.
J Ovarian Res ; 16(1): 195, 2023 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-37730647

RESUMO

BACKGROUND: Natural cycle- in vitro fertilization (NC-IVF) is particularly recommended for women with decreased ovarian reserve (DOR) or poor response to controlled ovarian hyperstimulation. In these cases, it can be challenging to determine the optimal timing for a trigger, and follicles of varying sizes are typically obtained. The influence of follicular size on IVF outcomes in women with DOR remains uncertain. This study aims to investigate the association between different follicular sizes and NC-IVF outcomes in women with DOR. METHODS: A retrospective cohort study involving 477 NC-IVF cycles from 2015 to 2021 was conducted at one of the largest reproductive medical centers in China. Follicular growth was monitored using transvaginal ultrasonography, and the follicles were categorized into three groups based on their diameters:12-15 mm; 16-17 mm and ≥ 18 mm. Laboratory outcomes were evaluated, including the number of canceled cycles, number of oocytes retrieved, 2PN fertilization, embryo and good-quality embryo, fresh embryo transfers, and frozen embryo. Additionally, clinical outcomes, such as the rates of biochemical pregnancy, clinical pregnancy, ongoing pregnancy, and live birth, were investigated and compared among the different follicular size groups. RESULTS: A total of 68 cycles with follicles sizes of 12-15 mm, 171 cycles with follicles sizes of 16-17 mm, and 236 cycles with follicles sizes ≥ 18 mm were included in this study. The basic characteristics, including female age, male age, infertility duration, infertility type, and parity, were comparable among the groups. The rate of cycle cancellation in the 12-15 mm group (27.9%) was higher compared to the other two groups. The 2PN fertilization rate for follicles with a diameter of 16-17 mm (75.0%) was higher than that of follicles with a diameter of 12-15 mm (61.3%) and ≥ 18 mm (56.6%) (P = 0.031). Other clinical outcomes, such as the number of oocytes retrieved, good-quality embryos, fresh embryo transfers, and frozen embryos, did not show significant differences between groups. Further analysis revealed no significant difference in the rates of clinical pregnancy, ongoing pregnancy, and live birth rate among the three groups. CONCLUSIONS: This study indicates that in women with DOR undergoing NC-IVF, if a premature LH surge occurs and small follicles are retrieved, these follicles can still be used in subsequent treatment and provide a comparable chance of clinical pregnancy to normal-sized follicles. These findings have important implications for guiding NC-IVF treatment in patients with severe DOR. TRIAL REGISTRATION NUMBER: N/A.


Assuntos
Infertilidade , Reserva Ovariana , Gravidez , Humanos , Feminino , Masculino , Estudos Retrospectivos , Folículo Ovariano/diagnóstico por imagem , Fertilização in vitro
11.
Front Endocrinol (Lausanne) ; 13: 877471, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35784567

RESUMO

Objective: To explore the clinical application value of half-ICSI treatment for infertility in assisted reproductive technology. Method: A retrospective analysis of 1130 half-ICSI treatments was conducted at the Affiliated Reproductive Hospital of Shandong University from January 2011 to December 2015. Patients with low fertilization rates in previous cycles, primary infertility for >5 years with unexplained reason, or secondary infertility for >5 years without fallopian tube factor were involved in this study. The 2PN rate, high-quality embryo rate, oocyte utilization rate, and clinical outcomes were compared between IVF insemination group (IVF group) and ICSI insemination group (ICSI group). The clinical outcome of half-ICSI insemination treatment, grouped according primary and secondary infertility, was also analyzed. Results: Compared with IVF, ICSI resulted in a significantly higher 2PN rate (74.8% vs. 62.9%), high-quality embryo rate (54.6% vs. 51.7%), and oocyte utilization rate (35.9% vs. 32.8%; P<0.05). Among the 884 fresh-embryo transfer cycles, there were no notable differences in clinical pregnancy rate, live birth rate, or neonatal abnormality rate between the IVF and ICSI groups. Among the 792 primary infertility cycles, ICSI resulted in a significantly higher 2PN rate, high-quality embryo rate, and oocyte utilization rate compared with IVF (75.3% vs. 62.4%, 54.3% vs. 50.8%, 36.4% vs. 32.6%, P<0.05). For the 338 secondary infertility cycles, ICSI resulted in a significantly higher 2PN rate (73.6% vs. 63.9%, P<0.05) compared with IVF, but there were no notable differences in other laboratory results. Moreover, the biochemical pregnancy rate of the ICSI group was significantly lower than for IVF in secondary infertility cycles (49.3% vs. 65.6%; P<0.05). A total of 89 cycles (7.9%) with complete IVF fertilization failure showed a low second polar body (2PB) rate (33.6%) after a 5-h short-time fertilization period, including 34 cycles (3.0%) with no 2PB oocytes observed in the IVF group. Conclusion: ICSI insemination improved laboratory results compared with IVF insemination, however, fresh-embryo transfer of ICSI originated embryos did not improve clinical pregnancy and live birth rates. Rescue ICSI has been successfully applied in clinical IVF insemination to avoid fertilization failure. Therefore, as an extra intervention, it is suggested that ICSI be used judiciously.


Assuntos
Infertilidade , Injeções de Esperma Intracitoplásmicas , Embrião de Mamíferos , Feminino , Humanos , Masculino , Gravidez , Estudos Retrospectivos , Sêmen
12.
Mediastinum ; 6: 4, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35340837

RESUMO

Objective: To summarize the principal studies investigating the role of postoperative radiation therapy (PORT) for non-small cell lung cancer (NSCLC) and to discuss the recent major breakthroughs deriving from the Lung ART trial, in order to provide a real-world scenario of the management of resected NSCLC patients. Background: Surgery followed by platinum-based chemotherapy remains the mainstay of adjuvant treatments for completely resected stage II and IIIA NSCLC. Less consistent is the employment of PORT, as no significant benefit was clearly identified from the previous published meta-analysis. Furthermore, the recent results of Lung ART trial questioned for the first time the efficacy of PORT for pathological N2 (pN2) NSCLC patients. Hence, the need to define if PORT still has a role for resected NSCLC and which subgroup of patients could benefit most from this treatment. Methods: A literature search of PubMed was performed to identify publications, including prospective and retrospective clinical studies, meta-analysis and systematic review of PORT for NSCLC. No limit concerning years of publication or publication status were applied. Only papers using the English language were selected. The ESMO 2020 and ESMO 2021 online resources were used to analyze the Lung ART trial results. The authors provide a narrative summary of the findings and implications of these studies and how they improve the clinical practice. Conclusions: PORT was considered the standard of care for patients with completely resected pN2 NSCLC based on the results of an old meta-analysis that did not demonstrate a detrimental effect. The more recent randomized phase III Lung ART trial concluded that PORT could not anymore be recommended for pN2 NSCLC as a significant benefit in terms of 3 years disease-free survival (DFS) was not reached and an increased rate of radiotherapy related toxicity was observed. Retrospective studies suggest a possible role of PORT for incompletely resected NSCLC patients and those with an extranodal extension (ENE), but this issue needs to be reinforced from randomized prospective trials. The extensive publication of Lung ART trial is largely awaited to define if there is a role of PORT for resected NSCLC patients.

13.
MethodsX ; 8: 101347, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34430250

RESUMO

Hyperscanning is an emerging technique that allows for the study of brain similarities between interacting individuals. This methodology has powerful implications for understanding the neural basis of joint actions, such as conversation; however, it also demands precise time-locking between the different brain recordings and sensory stimulation. Such precise timing, nevertheless, is often difficult to achieve. Recording auditory stimuli jointly with the ongoing high temporal resolution neurophysiological signal presents an effective way to control timing asynchronies offline between the digital trigger sent by the stimulation program and the actual onset of the auditory stimulus delivered to participants via speakers/headphones. This configuration is particularly challenging in hyperscanning setups due to the general increased complexity of the methodology. In other designs using the related technique of pseudo-hyperscanning, combined brain-auditory recordings are also a highly desirable feature, since reliable offline synchronization can be performed by using the shared audio signal. Here, we describe two hardware configurations wherein the real-time delivered auditory stimulus is recorded jointly with ongoing electroencephalographic (EEG) recordings. Specifically, we describe and provide customized implementations for joint EEG-audio recording in hyperscanning and pseudo-hyperscanning paradigms using hardware and software from Brain Products GmbH.•Joint EEG-audio recording configuration for hyperscanning and pseudo-hyperscanning paradigms.•Near zero-latency playback of auditory signal captured by a microphone.•Precise alignment between EEG and auditory stimulation.

14.
Appl Radiat Isot ; 156: 108842, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31732424

RESUMO

The flux-weighted average cross sections of 127I(γ,xn)126,124,123I reactions were experimentally determined with the bremsstrahlung end-point energies of 50 and 70 MeV by activation and off-line γ-ray spectrometric technique, using the 100 MeV electron linac at the Pohang Accelerator Laboratory, Korea. The 127I(γ,xn)126-121I reaction cross sections as a function of photon energy were theoretically calculated using the TALYS 1.8 code. The flux-weighted average cross sections of 127I(γ, xn)126,124,123I reactions as a function of bremsstrahlung end-point energies were also obtained from the literature and TALYS data based on mono-energetic photons and are found to be in close agreement with the present data. The experimental and theoretical 127I(γ, xn)126-121I reaction cross-sections increase with bremsstrahlung energy, which indicates the role of excitation energy. After a certain energy, the individual 127I(γ, xn)126-121I reaction cross sections decrease with increase of bremsstrahlung energy due to opening of other reactions, which indicates sharing of energy in different reaction channels. The radioactive iodine isotopes production cross-sections are important for the useful medical purpose.

15.
J Steroid Biochem Mol Biol ; 139: 114-21, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23685395

RESUMO

The objective is to present an overview of trials and appreciate the relevant data on the effect of steroids pretreatment (oral contraceptives, 17ß-estradiol and estradiol valerate) in assisted reproduction cycles. The subject of the study is to evaluate the clinical characteristics during steroids pretreatment cycles focused on the prevention of ovarian cysts, the positive contraceptive effect on the onset of regular period during long gonadotropin releasing hormone agonist protocol. In gonadotropin releasing hormone antagonist protocol the review is interested in supporting ovarian stimulation in low responders, the idea of cycle scheduling and improving treatment outcomes. The method is a review from MEDLINE/Pubmed database between 1994 and July 2012. We identified 15 randomised controlled trials (n=3069 patients). One trail (n=83 patients) assessed GnRH agonist protocol with or without steroids pretreatment, 8 trials (n=1884 patients) assessed GnRH antagonist protocols with or without steroids pretreatment and 6 trials (n=1102 patients) assessed GnRH antagonist protocols versus agonist ones with steroid pretreatment. Data demonstrates that oral contraceptives offer the effective prevention of functional ovarian cysts, the predictable onset of period during desensitisation. Existing data suggest that pretreatment with oral contraceptive pills or estradiol valerate give no advantage concerning number of oocytes or pregnancy rate. Pretreatment with oral contraceptive pills aiming to avoid weekend oocytes retrievals has to be more elucidated. In low responders oral contraceptive pill pretreatment may be beneficial in improving ovarian responses by reducing the amount of gonadotropins and the number of days required for ovarian stimulation. Current research indicates that also 17ß-estradiol may be encouraging pretreatment in low responders and in cycle scheduling. This article is part of a Special Issue entitled 'Pregnancy and Steroids'.


Assuntos
Anticoncepcionais Orais/administração & dosagem , Estradiol/análogos & derivados , Técnicas de Reprodução Assistida , Estradiol/administração & dosagem , Feminino , Hormônio Liberador de Gonadotropina/agonistas , Hormônio Liberador de Gonadotropina/antagonistas & inibidores , Hormônio Liberador de Gonadotropina/fisiologia , Humanos , Cistos Ovarianos/prevenção & controle , Gravidez , Taxa de Gravidez , Ensaios Clínicos Controlados Aleatórios como Assunto , Resultado do Tratamento
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