Publications by authors named "David Y L Chan"

Infertility is associated with the alteration of the seminal microbiome. However, the onset of dysbiosis remains controversial and the involvement of host factors remains elusive. This study investigates the alterations of the seminal microbiome in male infertility and examines the association and function of DEFB119, a reproductive-tract-specific host antimicrobial peptide, on the seminal microbiome and male fertility.

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Background: Time-lapse imaging systems for embryo incubation and selection might improve outcomes of in-vitro fertilisation (IVF) and intracytoplasmic sperm injection (ICSI) treatment due to undisturbed embryo culture conditions, improved embryo selection, or both. However, the benefit remains uncertain. We aimed to evaluate the effectiveness of time-lapse imaging systems providing undisturbed culture and embryo selection, and time-lapse imaging systems providing only undisturbed culture, and compared each with standard care without time-lapse imaging.

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Article Synopsis
  • Scientists wanted to find out if germs from sperm and fluid around eggs could contaminate the liquid used to grow embryos during fertility treatments.
  • They collected samples from 61 couples and studied the germs using special techniques, discovering that 82.5% of the cases had germs from the sperm in the growing media.
  • While some germs in sperm were linked to poorer sperm health and certain germs in egg fluid were associated with female infertility, they didn’t find a link between these germs and the success of the fertility treatments.
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Background: The widespread interest in male reproductive health (MRH), fueled by emerging evidence, such as the global decline in sperm counts, has intensified concerns about the status of MRH. Consequently, there is a pressing requirement for a strategic, systematic approach to identifying critical questions, collecting pertinent information, and utilizing these data to develop evidence-based strategies. The methods for addressing these questions and the pathways toward their answers will inevitably vary based on the variations in cultural, geopolitical, and health-related contexts.

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Background: Sertoli cell-only syndrome (SCOS) is the most serious pathological type of non-obstructive azoospermia. Recently, several genes related to SCOS have been identified, including FANCM, TEX14, NR5A1, NANOS2, PLK4, WNK3, and FANCA, but they cannot fully explain the pathogenesis of SCOS. This study attempted to explain spermatogenesis dysfunction in SCOS through testicular tissue RNA sequencing and to provide new targets for SCOS diagnosis and therapy.

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Article Synopsis
  • * A study with 111 couples found that male blood levels of certain metals were not significantly related to oocyte fertilization or embryo quality, but factors like antral follicle count and iron levels were associated with better pregnancy success.
  • * Specific metals like manganese and selenium in male partners were linked to reduced pregnancy and live birth rates during frozen embryo cycles, suggesting that while some metals impact outcomes, iron showed positive correlations with successful pregnancies.
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Ovarian dermoid cysts, also called mature cystic teratomas (MCTs), account for 69% of ovarian germ cell tumors in young women. The tumors are formed by tissues derived from three germ layers, and sebaceous materials are most commonly seen. The origin of MCTs is widely considered to be the germ cell origin, which completes meiosis I.

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Article Synopsis
  • Sperm carries genetic material from the father and can also have special markers that help in making the embryo grow properly.
  • Recent research showed that small noncoding RNA (sncRNA) in sperm changes as the sperm moves from the testicles to the epididymis, which could affect how the baby develops.
  • The study looks at how these changes in sperm could lead to infertility in men and possibly health problems in their children, and how this info might help with advanced reproductive methods.
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Currently, routine genetic investigation for male infertility includes karyotyping analysis and PCR for Y chromosomal microdeletions to provide prognostic information such as sperm retrieval success rate. However, over 85% of male infertility remain idiopathic. We assessed 101 male patients with primary infertility in a retrospective cohort analysis who have previously received negative results from standard-of-care tests.

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Article Synopsis
  • The text discusses the prevalence of abnormal oocytes and embryos in assisted reproductive technology (ART) and highlights the importance of gene expression in embryo development and quality for successful implantation.
  • It summarizes findings on 64 genes associated with morphological defects in embryos, noting that many of these genes have been identified in humans, which may indicate their role in embryonic changes.
  • Additionally, the review includes a database analysis of over 3000 oocytes/embryos, suggesting that understanding gene alterations can improve IVF practices, aid in selecting viable embryos, and assist patients with genetic disorders through preimplantation genetic testing.
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Article Synopsis
  • * Studies indicate that MSTN is crucial for various processes related to female fertility, such as follicular development and oocyte maturation, and its dysregulation may be linked to reproductive disorders like PCOS and preeclampsia.
  • * This review highlights the need for more research on MSTN in the context of female reproduction, summarizing its expression and functions in both normal and pathological conditions.
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Objective: The culture failure rate of conventional karyotyping in products of conception evacuated from early pregnancy loss by traditional electrical vacuum aspiration and/or dilation & curettage remains high. We aim to determine whether obtaining products of conception from early pregnancy loss via another evacuation approach, ultrasound-guided manual vacuum aspiration, could decrease the culture failure rate of karyotyping.

Methods: For patients with early pregnancy loss, ultrasound-guided manual vacuum aspiration (Case group) and traditional electrical vacuum aspiration and/or dilation & curettage (Control group) were applied as surgical methods for pregnancy loss management respectively.

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  • - The article was retracted following a disagreement among the authors about who should be credited as co-authors.
  • - Changes to authorship were made during the revision process without informing the handling Editor, violating journal policies.
  • - The Editor-in-Chief deemed the situation unacceptable, leading to the retraction of the article.
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Purpose: The prognostic value of desmoplastic reaction (DR) has not been investigated in colorectal cancer (CRC) patients with synchronous peritoneal metastasis (SPM). The present study aimed to identify whether DR can predict overall survival (OS) and develop a novel prognostic nomogram.

Methods: CRC patients with SPM were enrolled from a single center between July 2007 and July 2019.

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  • A systematic review and meta-analysis were conducted to evaluate the effects of nonoxynol-9 (N-9), a spermicide, on human sperm motility and structure based on phase I and II clinical trials.
  • Results showed that treatment with N-9 decreased the number of progressive motile sperm and shortened their penetration distance, while also damaging sperm structures like the acrosome and mitochondria.
  • Overall, the findings indicate that N-9 significantly impairs sperm function, leading to reduced motility and increased risk of contraceptive failure despite its long history of use as a spermicide.
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Patients with asthenozoospermia often present multiple defects in sperm functions apart from a decrease in sperm motility. However, the etiological factors underlying these multifaceted defects remain mostly unexplored, which may lead to unnecessary treatment and unsatisfactory assisted reproductive technologies (ART) outcome. Here, we show that the protein levels of CD147 were lowered in sperm obtained from asthenozoospermic infertile patients exhibiting defects in both sperm motility and the acrosome reaction.

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Research Question: Is air pollution related to IVF outcomes in a heavily polluted city in China?

Design: A retrospective cohort study of 8628 fresh, autologous IVF cycles was conducted for the first time at the Reproductive Medicine Center of The Third Affiliated Hospital of Zhengzhou University between May 2014 and December 2018 (oocyte retrieval date). The exposure was divided into four periods (gonadotrophin injection to oocyte retrieval [P1], oocyte retrieval to embryo transfer [P2], 1 day after embryo transfer to embryo transfer +14 days [P3] and gonadotrophin injection to embryo transfer +14 days [P4]) and four levels (Q1-Q4 according to their 25th, 50th and 75th percentiles).

Results: An interquartile range increase (Q2 versus Q1) in particulate matter ≤10 µm (PM10) during P3 and P4 and sulphur dioxide (SO) during P3 significantly decreased the clinical pregnancy rate (adjusted odds ratio [aOR] 0.

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To analyze the clinical characteristics and renal pathological manifestations of patients with monoclonal gammopathy (MG) and kidney injury. This was a multicenter retrospective cohort study conducted at four tertiary hospitals in China. The study population comprised patients with MG admitted from January 1 2013 to December 31 2020.

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Background: The association between metal/metalloid exposure on human sperm quality is still inconclusive. There is a lack of data on the effect of metal/metalloid on sperm function.

Methods: The aim of this study was to clarify the association between blood metal/metalloid concentration and traditional and functional sperm parameters, the blood concentration of Pb, Hg, Cd, As, Ni, Mo, Zn, Cu, Se, Fe, Mg, Cr and Ca of 288 men in Hong Kong were assessed by inductively coupled plasma-mass spectrometry, and sperm parameters including sperm concentration, motility, morphology, vitality, total sperm count, total motile sperm count, sperm DNA fragmentation and sperm acrosome reaction were measured.

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Immature oocytes retrieved from fertilization (IVF) and clinical maturation (IVM) is a common problem, especially in patients with advanced age, poor ovarian response (POR), or polycystic ovary syndrome (PCOS). Considering there is no common name to describe this group of oocytes, we suggest naming all of immature oocytes retrieved from IVF and clinical IVM cycles as 'Medical Unusable Oocytes' (MUO) as none of them will be used for subsequent treatment and will eventually be discarded. Scientists attempt to improve the clinical utilization rate of MUO instead of discarding them.

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Objectives: To evaluate the predictive value of endometrial thickness (EMT) during in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) cycles for ectopic pregnancy (EP).

Methods: A total of 3068 patients with 3117 fresh IVF/ICSI cycles between January 2016 and February 2019 from the Reproductive Medicine Center of Sun Yat-Sen Memorial Hospital were included in this retrospective study. The patients were divided into an EP group (n = 92) and an intrauterine pregnancy (IUP) group (n = 3025).

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Selection of the best quality embryo is the key for a faithful implantation in in vitro fertilization (IVF) practice. However, the process of evaluating numerous images captured by time-lapse imaging (TLI) system is time-consuming and some important features cannot be recognized by naked eyes. Convolutional neural network (CNN) is used in medical imaging yet in IVF.

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Systemic lupus erythematosus (SLE) is a chronic inflammatory disease that can affect fertility. There is currently little information regarding the semen profile of males with SLE. Moreover, there is no consensus on an appropriate period of sexual abstinence for semen analysis and on the use of DNA fragmentation assay, together with multiple semen analyses to document the semen profile in this clinical population.

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