Effects of thermoregulation on human sleep patterns: A mathematical model of sleep-wake cycles with REM-NREM subcircuit

In this paper we construct a mathematical model of human sleep/wake regulation with thermoregulation and temperature e ects. Simulations of this model show features previously presented in experimental data such as elongation of duration and number of REM bouts across the night as well as the appearance of awakenings due to deviations in body temperature from thermoneutrality. This model helps to demonstrate the importance of temperature in the sleep cycle. Further modi cations of the model to include more temperature e ects on other aspects of sleep regulation such as sleep and REM latency are discussedPostprint (author's final draft

African experience with sperm morphology training courses

This paper reports on the results of a 6-year ongoing training and quality control programme for sperm morphology. The programme consists of a 5-day semenology workshop, during which participants receive intensive training on issues such as sperm concentration, motility, vitality and morphology. Following the workshop, all the participants are enrolled in a continuous quality control (CQC) programme for sperm morphology. These workshops and quality control programmes are presented by the Department of Obstetrics and Gynaecology at Tygerberg Hospital (South Africa) in conjunction with the World Health Organization's (WHO) Special Programme for Research Development and Research Training. Seventy individuals from 11 countries in sub-Saharan Africa have been trained since 1997; 58 of these are still participating in the quality control programme. Using the results from the quality control programme, participants were classified according to their sperm morphology reading skills recorded over an extended period. It is concluded that an external quality control programme can be highly successful, on condition that it is presented continuously with a 3-4 month interval between tests.Articl

Comparison between propidium iodide and 7-amino-actinomycin-D for viability assessment during flow cytometric analyses of the human sperm acrosome

Evaluation of the acrosome reaction can shed light on the fertilising competence of spermatozoa. To eliminate false-positive results when evaluating the acrosome status of human sperm cells, two viability probes propidium iodide (PI) and 7-amino-actinomycin D (7-AAD) were compared for their ability to stain nonviable cells post-fixation and permeabilisation. Both the mean fluorescence and % dead cells differed significantly with time (P < 0.0001). Unlike PI, 7-AAD did not leach from cells and fluorescence remained stable for up to 4 h. Furthermore, 7-AAD proved to be a proficient marker to exclude dead sperm cells during flow cytometric evaluation of ionophore-induced acrosome reaction. © 2009 Blackwell Publishing Ltd.Evaluation of the acrosome reaction can shed light on the fertilising competence of spermatozoa. To eliminate false-positive results when evaluating the acrosome status of human sperm cells, two viability probes propidium iodide (PI) and 7-amino-actinomycin D (7-AAD) were compared for their ability to stain nonviable cells post-fixation and permeabilisation. Both the mean fluorescence and % dead cells differed significantly with time (P < 0.0001). Unlike PI, 7-AAD did not leach from cells and fluorescence remained stable for up to 4 h. Furthermore, 7-AAD proved to be a proficient marker to exclude dead sperm cells during flow cytometric evaluation of ionophore-induced acrosome reaction. © 2009 Blackwell Publishing Ltd.ArticleArticl

The influence of sperm/zona pellucida collision rates on zona binding

The satisfying success rates reported with intra-cytoplasmic sperm injection (ICSI) urged clinicians and scientists to re-address the emphasis in the management of the male factor patient towards gamete manipulation in order to circumvent the underlying problem causing fertilization failure. We have designed a study to (i) calculate the collision rate of a sperm population with the human zona pellucida, using a mathematical hypothesis and (ii) use the calculated collision rate to evaluate subsequent zona binding results obtained under hemizona assay conditions. Microdroplets were used to co-incubate sperm and human oocytes in order to evaluate zona binding. Using microvolumes, the track followed by sperm, as well as the maximum distance travelled were employed to calculate the collision rate of sperm and zona pellucida. The sperm concentrations of swim up samples were adjusted to 4 x 106 and 0.8 x 106 sperm ml-1. Five separate droplets each of 20 μl containing 4 x 106 sperm ml (80 000 motile sperm) and 200 μl containing 0.8 x 106 sperm ml-1 (160 000 motile sperm), respectively, were prepared. Both volumes were incubated for 18 h at 37 °C. The mean (± SD) number of spermatozoa tightly bound to hemizona, incubated in 20 μl and 200 μl sperm droplets, was 2444±612 and 548±315, respectively (P=0.0001). The results can be used as a guideline to calculate the optimum insemination concentration needed for a specific sperm population to ensure the maximum collision rates with the oocyte.Articl

Can a cumulus cell complex be used to select spermatozoa for assisted reproduction?

Since the onset of intracytoplasmic sperm injection, researchers have intensified the search for the ideal spermatozoa to be used for injection. The aim of this study was to record the functional role of cumulus cell interaction with human spermatozoa as far as capacitation, acrosome reaction, morphology, zona binding and chromatin packaging quality are concerned. Using a previously described cumulus oophorus model, we recorded specific sperm functional aspects of sperm populations that transverse a cumulus cells mass. Control spermatozoa were kept under similar experimental conditions in the culture media only. Results indicated cumulus cells to be beneficial to spermatozoa as far as functional and capacitational events are concerned. The mean percentage of morphologically normal spermatozoa in the control sample was 6.9%, while the spermatozoa that traversed the cumulus oophorus (test) had a significantly higher percentage of normal forms (mean 9.5%; P ≤ 0.01). We observed a decline in the percentage of CMA3-positive spermatozoa when we compared the control population (49.1%) to the test, i.e. 38.4%, (P = <0.05), thus implying that the spermatozoa with good chromatin condensation increased during cumulus penetration. Significantly more (P ≤ 0.01) acrosome-reacted spermatozoa were found in the penetrated spermatozoa (mean 23%) than in the control spermatozoa (mean 11%). The test spermatozoa had a higher zona binding capacity with significantly more (P ≤ 0.01) tightly bound spermatozoa on the hemizona (61 ± 15) than the control spermatozoa (47 ± 18). In the absence of sophisticated and expensive sperm selection products, the use of a cumulus model to select spermatozoa for intracellular sperm injection seems to be an alternative method. © 2009 Blackwell Verlag GmbH.Articl

The clinical significance of sperm-zona pellucida binding: 17 Years later

The development of homologous functional bioassays for sperm quality assessment has been a focal point of reproductive biologists in order to provide a scientifically-based diagnosis in cases of fertilization failure. The availability of viable oocytes still remains an important limiting factor for laboratories to embark on the methodology of assays that examine sperm-oocyte interaction. The use of zonae pellucidae obtained from oocytes derived from post mortem tissue and failed in vitro fertilization cycles, enhanced the availability of zona material. Sperm-zona pellucida binding has been illustrated to be an essential requisite during human fertilization. This fundamental biological step can be measured under hemizona assay as well intact-oocyte test conditions. The sensitivity and specificity of sperm-zona binding results indicated the assay to be positively and significantly correlated with in vitro fertilization outcome. Furthermore, highly significant correlations were demonstrated between normal sperm morphology, hyperactivated motility, sperm creatine kinase activity and the zona binding capacity of a given sperm sample. It was concluded that andrology testing remains an ever-growing component in the work-up of the infertile couple. We enter the next millennium with many questions that remain to be answered by the hand of efficacious screening techniques and a new formidable therapy in intracytoplasmicc sperm injection.Revie

The role of paternal chromosomes and sperm morphology on the outcome of intracytoplasmic sperm injection

The study investigated the possible relationship between the X/Y chromosomes bearing spermatozoa and the outcome of intracytoplasmic sperm injection (ICSI) therapy and morphological appearance/shape (Tygerberg criteria) of the sperm cell injected into the oocyte during ICSI therapy and fertilisation. Thirty-nine patients were recruited for the study from an assisted reproductive programme. Semen samples were prepared by using gradient centrifugation techniques. Prior to injection sperm images were captured using high-quality video graphic equipment. Sperm selection was based on the concept of 'best-looking' spermatozoa i.e. spermatozoa lacking gross and obvious malformations such as broken necks, cytoplasmic droplets, amorphous or elongated heads. Photomicrographs of each sperm cell were produced from video footage. The photographical material was used to determine the basic shape and the actual length-to-width ratio of the injected sperm heads. Embryo biopsies and fluorescent in situ hybridisation (FISH) was performed on 12 randomly selected couples from a set of 39. Embryos were evaluated on day 3 for development and embryo transfer. Embryo biopsies and FISH analyses were performed on those embryos that showed no developmental potential following injection. It was found that 70% of the embryos that showed no developmental potential were Y chromosome-bearing embryos. The sperm selection process for ICSI based on the approach of choosing the 'best-looking' spermatozoon in the ejaculate seems to provide cells that can be classified as normal based on the length-to-width ratio set by the World Health Organization for normal cells. © 2006 The Authors.Articl

The establishment of sperm morphology satellite training laboratories in Africa

Discrepancies in the results of semen analysis can be caused by a variety of factors, for example, a microscope for semen analysis can be situated in the practice of an urologist, cytologist or microbiologist, or even in a health care office in the countryside in a developing country. The study aimed to evaluate the (i) sperm morphology assessment skills of the participants who attended WHO seminology workshops and (ii) to appraise the possibility of using trained technologists to set up satellite training facilities in their own area. The Centre for Research in Reproductive Health, Ogun State University Teaching Hospital (Nigeria) initiated training sessions in their area. Subsequently, 16 technologists were trained in three sessions. Papanicolaou-stained slides, supplied by Tygerberg were used as test material. Pre- and post-training results were used to calculate the mean percentage of normal cells as well as the percentage deviation from the reference laboratory. The mean percentage normal spermatozoa recorded by the Nigerian trainees during pre-training evaluations differed by 38% from the reference value, compared with a post-training difference of 16% (P < 0.001). Tertiary academic hospitals can play an important educational role in the region. The present results underline the power of long distance educational programmes. Similar laboratories are currently being set up in Kenya and Zambia. © 2005 Blackwell Publishing Ltd.Articl

Does training assist medical laboratory scientists with better evaluation of sperm morphology?

This study aimed to evaluate the quality of sperm morphology evaluation skills of 16 technologists who are responsible for semen analyses in their institution. The 1-day workshop was held at the Centre for Research in Reproductive Health in Sagamu, Nigeria. Participants were requested to complete a questionnaire that provided information regarding their experience and training as technologists in their institution. The workshop consisted of 4 sections, namely (i) pre-training test, (ii) lectures on morphometric characteristics and details of normal and abnormal sperm (iii) a laboratory-based hands-on, post training test and (iv) a consensus training session. The findings of the questionnaire indicated that none of the participants had any previous formal training and that all participants had very little knowledge about the morphological appearance of normal spermatozoa. These findings were supported by the results obtained during the pre-training session that showed a mean percentage difference of 24% between the reference and participant's values. These somewhat alarming results highlight the need for training facilities for technologists who work in the clinical diagnostic field of reproductive science.Articl