Ralf Henkel

Ralf Henkel
LogixX Pharma · LogixX Fertility

PhD, Habil.

About

363
Publications
134,021
Reads
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8,605
Citations
Citations since 2016
226 Research Items
5679 Citations
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201620172018201920202021202202004006008001,0001,2001,400
201620172018201920202021202202004006008001,0001,2001,400
Introduction
Ralf Henkel is Chief Scientific Advisor at LogixXPharma, Reading, UK, Visiting Reader in the Dept. of Metabolism, Digestion & Reproduction at Imperial College London, UK, Extraord. Prof. at UWC, Honorary Prof. at Universidad Peruana Cayetano Heredia, Lima, Peru, and Adj. Snr. Scientist at ACRM, Cleveland Clinic, Cleveland, OH. Ralf is also Editor-in-Chief of ANDROLOGIA. Thus far, Ralf published 176 research papers and review articles, 48 book chapters as well as 3 books; his h-index is 43.
Additional affiliations
April 2018 - present
American Centre for Reproductive Medicine
Position
  • Senior Researcher
Description
  • Andrology, Oxidative stress
January 2018 - present
John Wiley And Sons
Position
  • Editor
Description
  • Editor-in-Chief
May 2017 - August 2017
Cleveland Clinic
Position
  • Professor

Publications

Publications (363)
Article
Full-text available
Purpose: Despite the significant role of varicocele in the pathogenesis of male infertility, the impact of varicocele repair (VR) on conventional semen parameters remains controversial. Only a few systematic reviews and meta-analyses (SRMAs) have evaluated the impact of VR on sperm concentration, total motility, and progressive motility, mostly us...
Article
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Background: Idiopathic causes of infertility is associated with oxidative stress. Antioxidants are known to scavenge the excessive production of reactive oxygen species (ROS). Green tea (Camellia sinensis) contains polyphenols that enhance its antioxidant potential. Aim: This study focused on the impact of aqueous green tea extract on normozoosper...
Article
Full-text available
Biomedical science is rapidly developing in terms of more transparency, openness and reproducibility of scientific publications. This is even more important for all studies that are based on results from basic semen examination. Recently two concordant documents have been published: the 6th edition of the WHO Laboratory Manual for the Examination a...
Article
Full-text available
This study aims to evaluate the expression of genes associated with the fertilisation potential and embryo development, sperm DNA fragmentation (SDF), and acrosome reaction in male partners of infertile couples with different sperm parameters compared to fertile men. First, male partners of infertile couples with abnormal (N = 25) and normal sperm...
Article
Full-text available
Antisperm antibodies (ASA), as a cause of male infertility, have been detected in infertile males as early as 1954. Multiple causes of ASA production have been identified, and they are due to an abnormal exposure of mature germ cells to the immune system. ASA testing (with mixed anti-globulin reaction, and immunobead binding test) was described in...
Article
Recurrence following varicocelectomy is an important cause of treatment failure and persistence of subnormal semen parameters. This original study was combined with a systemic review and meta‐analysis aiming to evaluate the efficacy of redo varicocelectomy on male fertility potential and pregnancy outcome. The retrospective study included 32 patien...
Article
Full-text available
Purpose Varicocele is a common problem among infertile men. Varicocele repair (VR) is frequently performed to improve semen parameters and the chances of pregnancy. However, there is a lack of consensus about the diagnosis, indications for VR and its outcomes. The aim of this study was to explore global practice patterns on the management of varico...
Chapter
Male infertility is considered as a multifactorial complex reproductive illness, and male urogenital infection and inflammation are crucial etiologies contributing up to 35% of all cases. Mostly triggered by sexually transmitted diseases and uropathogens, chronic manifestation of such infection may cause irreversible infertility in the male. Male u...
Chapter
Since the discovery by John MacLeod in 1943 that spermatozoa produce small amounts of hydrogen peroxide, a member of the so-called reactive oxygen species (ROS), the importance and functions of these highly reactive oxygen derivatives in physiology and pathology are a subject of numerous studies. It has been shown that they play essential roles, no...
Article
Full-text available
The inability to conceive is a baleful experience for thousands of couples worldwide. Among different well‐known reproductive techniques, medicinal plants have been utilized to treat male infertility. Medicinal plants, provide a therapeutic alternative, which is available and affordable for infertile couples. We investigated the direct effect of un...
Article
Research question Has seminal oxidation-reduction potential (ORP) clinical relevance for reproductive outcome. Design In this prospective observational study a total of 144 couples who had an ICSI cycle between June 2018 and December 2020 were included. The study included patients undergoing fresh ICSI cycles with autologous gametes. Cycles that h...
Article
Full-text available
Study question: We aim to develop, disseminate and implement a minimum data set, known as a core outcome set, for future male infertility research. What is known already: Research into male infertility can be challenging to design, conduct and report. Evidence from randomized trials can be difficult to interpret and of limited ability to inform cl...
Article
Full-text available
Sperm vitality testing is a basic semen examination that has been described in the World Health Organization (WHO) Laboratory Manual for the Examination and Processing of Human Semen from its primary edition, 40 years ago. Several methods can be used to test sperm vitality, such as the eosin-nigrosin (E-N) stain or the hypoosmotic swelling (HOS) te...
Article
Full-text available
Oxidative stress (OS) due to an imbalance between reactive oxygen species (ROS) and antioxidants has been established as an important factor that can negatively affect the outcomes of assisted reproductive techniques (ARTs). Excess ROS exert their pathological effects through damage to cellular lipids, organelles, and DNA, alteration of enzymatic f...
Article
Full-text available
American Center for Reproductive Medicine Reasearch Collaborators-2018
Article
The present study aimed to investigate the clinical role of standard sperm diagnosis parameters (sperm concentration, motility, morphology) as well as aniline blue staining of histones, 8‐OHdG, TUNEL assay were performed on semen samples in infertile men with oligoasthenoteratozoospermia (OAT). Thirty‐two infertile and ten proven fertile men were i...
Article
With the advance of assisted reproduction techniques, and the trend towards blastocyst culture and single embryo transfer, gamete and embryo assessment have gained greater importance in ART treatment. Embryo quality depends mainly on gamete quality and culture conditions. Oocyte maturity identification is necessary in order to plan fertilization ti...
Article
Full-text available
Purpose: This study provides a comprehensive analysis of research trends on the etiology, mechanisms, potential risk factors, diagnosis, prognosis, surgical and non-surgical treatment of varicocele, and clinical outcomes before and after varicocele repair. Materials and methods: Varicocele studies published between 1988 and 2020 were retrieved f...
Article
Purpose: Azoospermia is defined as the absence of spermatozoa in the pellet of a centrifuged semen sample. In fact, when a basic semen analysis fails to detect sperm in the ejaculate, there is still the possibility of detecting rare sperm after centrifugation of the sample and examination of the pellet. In this study, we assessed the role of Cytos...
Article
Full-text available
Varicocele, a condition associated with increased oxidative stress, negatively affects sperm DNA integrity and reduces pregnancy rates. However, the molecular mechanisms related to DNA integrity, damage, and repair in varicocele patients remain unclear. This study aimed to determine the role of DNA repair molecular mechanisms in varicocele-related...
Article
Full-text available
Semen analysis is the cornerstone of male fertility evaluation with WHO guidelines providing the basis for procedural standardization and reference values worldwide. The first WHO manual was published in 1980, and five editions have been subsequently released over the last four decades. The 6th Edition was published in July 2021. In this review, we...
Article
This retrospective cohort study aimed to explore whether paternal age and semen quality parameters affect the embryological and clinical outcomes of ICSI with oocyte donation. A total of 339 oocyte donation (OD)-ICSI cycles were categorized into four groups according to the semen parameter profiles of the male counterparts: normozoospermia (NS, n =...
Article
To identify the most prevalent chromosomal abnormalities in patients with non‐obstructive azoospermia (NOA), consolidate their surgical sperm retrieval (SSR) rates and determine the significant predictors of positive SSR in this patient population. A systematic review and meta‐analysis were performed following the Preferred Reporting Items for Syst...
Article
Full-text available
Background : The use of herbal medicine and alternative medicine is reported to be in up to 50% of prescriptions for benign prostate hyperplasia (BPH) in Europe, along with an increased global interest for holistic medicinal approaches. This study aimed to systematically review the published evidence investigating the use of herbal medicines as a t...
Article
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Purpose: In response to the COVID-19 pandemic, the American Center for Reproductive Medicine (ACRM) transitioned its annual training in assisted reproductive technology (ART) from a hands-on, laboratory-based training course to a fully online training endorsed by the American College of Embryology. Here we describe our experience and assess the qu...
Article
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Androgens, testosterone and dihydrotestosterone (DHT) are endocrine regulators of spermatogenesis and act via androgen receptor (AR). The aim of this study was to investigate the association(s) of AR (CAG repeat length), SRD5A2 (rs523349, V89L) and TNF‐α (rs1800629, ‐308G/A) polymorphisms with idiopathic male infertility in Turkish men. This case‐c...
Article
Immunological infertility contributes significantly to the etiology of idiopathic male infertility. Shielding the spermatogenic cells from systemic immune responses is fundamental to secure normal production of spermatozoa. The body’s immune system is tuned with the host self-components since the early postnatal period, while sperm first develops d...
Article
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Objective : To examine the effect of paternal age on intracytoplasmic sperm injection (ICSI) outcomes in unexplained infertility Subjects and Methods : This retrospective study, done at the Hamad Medical Corporation, Doha, Qatar screened infertile couples who underwent ICSI between 2014 and 2019 for the inclusion and exclusion criteria defining ‘u...
Article
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Our study objective was to assess the effect of various sperm DNA fragmentation levels on clinical intracytoplasmic sperm injection outcome. This retrospective study included 392 patients who underwent ICSI and performed sperm DNA fragmentation testing before the procedure. Based on sperm DNA fragmentation cut-off values, the patients were differen...
Article
Full-text available
Objective: To systematically review the available literature on the long-term effects of sexually transmitted diseases (STIs) on male reproductive functions. Methods: A PubMed search was conducted on 3 January 2021, and as a result, 952 articles were retrieved. Exclusion of irrelevant articles resulted in 36 articles, dating from 1998 to 2020, whic...
Article
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Purpose: The use of antioxidants is common practice in the management of infertile patients. However, there are no established guidelines by professional societies on antioxidant use for male infertility. Materials and methods: Using an online survey, this study aimed to evaluate the practice pattern of reproductive specialists to determine the...
Article
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Background: Computer-aided sperm analyzers (CASA) are currently used worldwide for semen analysis. However, there are doubts about their reliability to fully substitute the human operator. Therefore, this study aimed to systematically review the current literature comparing results from semen evaluation by both CASA-based and manual approaches. Met...
Article
Full-text available
Semen analysis is the first, and frequently, the only step in the evaluation of male fertility. Although the laboratory procedures are conducted according to the World Health Organization (WHO) guidelines, semen analysis and especially sperm morphology assessment is very difficult to standardize and obtain reproducible results. This is mainly due t...
Cover Page
Full-text available
Certificate for Work in ACRM Scientific Research, Mahsa
Cover Page
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Certificate for Work in ACRM Scientific Research, Sara
Article
Full-text available
The current WHO 2010 manual for human semen analysis defines leukocytospermia as the presence of peroxidase-positive leukocytes at a concentration >1×106/mL of semen. Granular leukocytes when activated are capable of generating high levels of reactive oxygen species in semen resulting in oxidative stress. Oxidative stress has been correlated with p...
Chapter
Full-text available
Within the male reproductive system, oxidative stress (OS) has been identified as prevailing etiology of male infertility. The effects of reactive oxygen species (ROS) on male fertility depend on the dimensions, “modus operandi” of the ROS and the oxido-reduction potential (ORP) of the male reproductive tract. Hereupon, for an adequate response to...
Article
Full-text available
In this study, we investigated the prevalence of sexual dysfunction among males with advanced chronic kidney disease and the effect of treating hyperprolactinemia among these patients. In this prospective study, patients were assessed with history, physical examination, hormonal assessment, and two questionnaires, IIEF and AIPE. Patients with hyper...
Article
Aspalathus linearis (rooibos) is a herbal medicinal plant originally from South Africa's fynbos and well known for its medicinal effects in treating different medical conditions. Rooibos contains significant levels of antioxidants capable of inhibiting the production of reactive oxygen species, which may improve seminal parameters. This study focus...
Article
Full-text available
Semen analysis is a basic test for evaluating male fertility potential, as it plays an essential role in driving the future management and treatment of infertility in couples. Manual semen analysis includes the evaluation of both macroscopic and microscopic parameters, whereas automated semen analysis is conducted through a computer-aided sperm ana...
Chapter
Selecting good-quality sperm for use in in-vitro fertilization is a key step in assisted reproduction. For many years purely morphological attributes have been used to assess suitability, but increasingly biochemical and molecular biological techniques are now identifying sperm with the best chances of producing viable and healthy embryos. Focusing...
Chapter
Selecting good-quality sperm for use in in-vitro fertilization is a key step in assisted reproduction. For many years purely morphological attributes have been used to assess suitability, but increasingly biochemical and molecular biological techniques are now identifying sperm with the best chances of producing viable and healthy embryos. Focusing...
Article
Full-text available
It is widely accepted that oxidative stress plays an important role in the pathophysiology of male infertility and that antioxidants could have a significant role in the treatment of male infertility. The main objectives of this study are: 1) to systematically review the current evidence for the utility of antioxidants in the treatment of male infe...
Article
The cryopreservation of spermatozoa has the main purpose of preserving male fertility. However, current preservation techniques have shown to produce lesions in the structure and alter sperm functions, probably due to the production of reactive oxygen species (ROS) during cryopreservation. To overcome the damage provoked by ROS, we introduced a nov...
Article
Varicocele ligation has been proven to restore semen parameters and improve pregnancy rates in men with clinical disease. However, its effect in men with severe oligozoospermia (SO) is less clearly elucidated. This original report and meta‐analysis examined the impact of subinguinal microsurgical varicocelectomy on semen parameters and fertility ou...
Article
Purpose: The objective of this scientometric analysis was to recognize the top 100 cited articles on 'Male infertility and Antioxidants' and analyze its publication characteristics. Materials and methods: The Scopus database was used to retrieve related articles and the top 100 identified based on citation rate. Results: The articles were publ...
Article
The cryopreservation of spermatozoa has the main purpose of preserving male fertility. However, current preservation techniques have shown to produce lesions in the structure and alter sperm functions, probably due to the production of reactive oxygen species (ROS) during cryopreservation. To overcome the damage provoked by ROS, we introduced a nov...
Article
Obesity is considered a global health problem affecting more than a third of the population. Complications of obesity include cardiovascular diseases, type 2 diabetes mellitus, malignancy (including prostatic cancer), neurodegeneration and accelerated ageing. In males, these further include erectile dysfunction, poor semen quality and subclinical p...
Article
In 2020, the COVID‐19 pandemic led to the suspension of the annual Summer Internship at the American Center for Reproductive Medicine (ACRM). To transit it into an online format, an inaugural 6‐week 2020 ACRM Online Mentorship Program was developed focusing on five core pillars of andrology research: scientific writing, scientific methodology, plag...
Article
It is estimated that infertility affects 8-12% of couples globally, with a male factor being a primary or contributing cause in approximately 50% of couples. Causes of male subfertility vary highly, but can be related to congenital, acquired, or idiopathic factors that impair spermatogenesis. Many health conditions can affect male fertility, which...
Chapter
Natural plant products have been used throughout human history for various purposes. At present, herbal products are being used to treat several health issues and conditions, as well as allergies, arthritis, migraine, fatigue, wounds, burns, gastrointestinal issues, skin infections, genetic disorders, and even cancer. Once a patient is stricken by...
Chapter
Among Asian populations, including that of the Indian subcontinent, herbal remedies have been practiced since ancient times for the management of many complex diseases, including andrological problems. The efficacy of herbal medicines has largely been attributed to the synergistic interactions of the individual components because they are used most...
Article
Full-text available
The aim of the study was to investigate whether the promoter methylation of XRCC1 and ERCC2 genes is associated with sperm DNA fragmentation and chromatin condensation in idiopathic oligoasthenoteratozoospermic men. This study involved 77 infertile men with idiopathic oligoasthenoteratozoospermia and 51 normozoospermic controls. The methylight meth...
Article
Obesity is a significant global health and socio-economic challenge, and considered an important risk factor for poor health outcomes including male reproductive dysfunction and infertility. As excess adiposity causes testicular dysfunction and infertility, novel therapeutic strategies require investigation. Nigella sativa (Ns) seed oil and metform...
Article
The effects of aqueous leaf extract of Moringa oleifera (MO) on human sperm functions and integrity was studied in vitro. Semen was obtained by masturbation after 3–5 days' abstinence from 34 healthy donors in Western Cape, South Africa. Liquefied semen was washed in human tubular fluid supplemented with 1% bovine serum albumin (HTF-BSA;1:5) with 1...
Article
Full-text available
Assisted reproductive technologies (ART) are considered as one of the primary mana gement options to address severe male factor infertility. The purpose of this study was to identify the research trends in the field of male infertility and ART over the past 20 years (2000-2019) by analysing scientometric data (the number of publications per year, a...
Book
Full-text available
Foreword The issue of herbal medicine has gained increasing worldwide attention. Considering that about 80% of the global population have to rely on traditional remedies including herbal medicine for their primary health care, it is extremely important to investigate if and how these herbal remedies work. In the past, important medicines such as As...
Cover Page
Full-text available
Herbal Medicine in Andrology: An Evidence-Based Update provides a comprehensive overview of ethnomedical approaches in andrology, including ethnopharmacology of plant extracts and relevant bioactive compounds. It highlights information on the availability of medicinal plants and the legal and procedural processes involved in developing a marketable...
Article
To investigate the semiquantitative methylation alterations of MLH1 and MSH2 and the possible association among methylation of MLH1 and MSH2, sperm DNA fragmentation and sperm chromatin condensation in idiopathic oligoasthenoteratozoospermic men. Seventy-five idiopathic infertile men and 52 fertile and/or normozoospermic men were included in the st...
Article
Full-text available
Purpose: To know which sperm selection technique, physiological intracytoplasmic sperm injection (PICSI) or magnetic-activated cell sorting (MACS), is better for the selection of sperm with abnormal sperm DNA fragmentation (SDF) in patients undergoing intracytoplasmic sperm injection (ICSI). Methods: A prospective randomized trial included 413 I...