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Biomedical subjects

N McClure

Publications and source records attributed to N McClure.

At least 19 recordsLinked to original sources
PubMed2005

Effects of vasectomy on spermatogenesis and fertility outcome after testicular sperm extraction combined with ICSI.

BACKGROUND: Each year 40,000 men have a vasectomy in the UK whilst another 2400 request a reversal to begin a second family. Sperm can now be obtained by testicular biopsy and subsequently used in assisted conception with ICSI. The study aims were to compare sperm yields of men post-vasectomy or with obstructive azoospermia (OA) of unknown aetiology with yields of fertile men and to assess any alteration in the clinical pregnancy rates after ICSI. METHODS: Testicular tissue was obtained by Trucut needle from men who had undergone a vasectomy >5 years previously or had OA from other causes and from fertile men during vasectomy. Seminiferous tubules were milked to measure sperm yields. Numbers of Sertoli cells and spermatids and thickness of the seminiferous tubule walls were assessed using quantitative computerized analysis. RESULTS AND CONCLUSIONS: Sperm yields/g testis were significantly decreased in men post-vasectomy and in men with OA, relative to fertile men. Significant reductions were also observed in early (40%) and mature (29%) spermatid numbers and an increase of 31% was seen in the seminiferous tubule wall (basal membrane and collagen thickness) of vasectomized men compared with fertile men. Clinical pregnancy rates in couples who had had a vasectomy were also significantly reduced.

Adult↗
PubMed2004

An algorithm to predict pregnancy in assisted reproduction.

BACKGROUND: Male fertility potential cannot be measured by conventional parameters for the assisted reproduction technique; ICSI. This study determines the relationship between testicular and ejaculated sperm mitochondrial (mt) DNA deletions, nuclear (n) DNA fragmentation, and fertilization and pregnancy rates in ICSI. METHODS: Ejaculated sperm were obtained from 77 men and testicular sperm from 28 men with obstructive azoospermia undergoing ICSI. Testicular sperm were retrieved using a Trucut needle. mtDNA was analysed using a long PCR. The alkaline Comet assay determined nDNA fragmentation. RESULTS: Of subjects who achieved a pregnancy (50%) using testicular sperm, only 26% had partners' sperm with wild-type (WT) mtDNA. Of pregnant subjects (38%) using ejaculated sperm, only 8% had partner sperm with WT mtDNA. In each, the successful group had less mtDNA deletions and less nDNA fragmentation. There were inverse relationships between pregnancy and mtDNA deletion numbers, size and nDNA fragmentation for both testicular and ejaculated sperm. No relationships were observed with fertilization rates. An algorithm for the prediction of pregnancy is presented based on the quality of sperm nDNA and mtDNA. CONCLUSION: In both testicular and ejaculated sperm, mtDNA deletions and nDNA fragmentation are closely associated with pregnancy in ICSI.

Algorithms↗
PubMed2002

The effects of cryopreservation on sperm morphology, motility and mitochondrial function.

BACKGROUND: The effects of cryoinjury were determined simultaneously on the mitochondrial function, motility, morphology and viability of ejaculated human sperm. METHOD: Rhodamine 123 (R123) uptake (% of sperm) and stain intensity were used to determine sperm mitochondrial activity before and after cryopreservation from the semen of 50 men attending for infertility investigation. Morphology was assessed using Tygerberg's strict criteria and viability was assessed by eosin Y. Sperm motility was measured using computer-assisted semen analysis (CASA). RESULTS: Freeze-thawing caused a 37% (P = 0.001) reduction in normal morphological forms of sperm. All CASA sperm motility parameters except amplitude of lateral head displacement were similarly reduced. R123 uptake and intensity within sperm mitochondria decreased by 36 and 47% respectively (both P = 0.001). In addition, there was a similar significant decrease (31%, P = 0.001) in the viability of the sperm. CONCLUSIONS: Sperm morphology, motility, mitochondrial activities and viability are equally susceptible to cryopreservation-induced damage. R123 intensity is a novel and robust indicator of mitochondrial function before and after such trauma.

Cell Survival↗
PubMed2002

Mitochondrial DNA deletions and nuclear DNA fragmentation in testicular and epididymal human sperm.

BACKGROUND: There are still concerns about the safety of intracytoplasmic sperm injection (ICSI) due to its brief clinical record and lack of animal testing. Testicular and epididymal sperm are now used routinely for ICSI in patients with obstructive azoospermia. The use of such immature sperm compounds fears, since little is known of their mitochondrial and nuclear DNA quality. METHODS: A modified long polymerase chain reaction (LPCR) was employed to study mitochondrial DNA (mtDNA) and a modified alkaline Comet assay to determine nuclear DNA (nDNA) fragmentation in testicular and epididymal sperm from men with obstructive azoospermia (n = 25) attending the Regional Fertility Centre. RESULTS: Testicular sperm displayed significantly more wild-type mtDNA (45% of patients) than epididymal sperm (16% of patients). They also had a lower incidence of multiple deletions and smaller mtDNA fragments. Epididymal sperm harboured more large-scale deletions (P < 0.05). There was a strong correlation between nuclear DNA fragmentation, the number of mtDNA deletions (r = 0.48, r = 0.50, P < 0.001) and their size (r = 0.58, r = 0.60, P < 0.001) in both epididymal and testicular sperm. CONCLUSION: This study suggests that mtDNA and nDNA of testicular sperm have fewer mutations and fragmentation than epididymal sperm and should be used in preference for ICSI in clinical treatment.

Base Sequence↗
PubMed2002

A comparison of mitochondrial and nuclear DNA status in testicular sperm from fertile men and those with obstructive azoospermia.

BACKGROUND: Mitochondria are vital to sperm as their motility powerhouses. They are also the only animal organelles with their own unique genome; encoding subunits for the complexes required for the electron transfer chain. METHODS: A modified long PCR technique was used to study mitochondrial DNA (mtDNA) in ejaculated and testicular sperm samples from fertile men undergoing vasectomy (n = 11) and testicular sperm from men with obstructive azoospermia (n = 25). Nuclear DNA (nDNA) fragmentation was measured by an alkaline gel electrophoresis (comet) assay. RESULTS: Wild-type mtDNA was detected in only 60% of fertile men's testicular sperm, 50% of their ejaculated sperm and 46% of testicular sperm from men with obstructive azoospermia. The incidence of mitochondrial deletions in testicular sperm of fertile and infertile men was not significantly different, but the mean size of the deletions was significantly less in testicular sperm from fertile men compared with men with obstructive azoospermia (P < 0.02). NDNA fragmentation in testicular sperm from fertile men and men with obstructive azoospermia was not significantly different. CONCLUSION: Multiple mtDNA deletions are common in testicular and ejaculated sperm from both fertile and infertile men. However, in males with obstructive azoospermia, the mtDNA deletions in testicular sperm are of a larger scale.

Base Sequence↗
PubMed2001

Objective psychomotor skills assessment of experienced, junior, and novice laparoscopists with virtual reality.

Objective assessment of psychomotor skills in surgery is now a priority; however, this assessment is difficult to achieve because of measurement difficulties associated with the reliability and validity of assessing surgical skills in vivo and in the laboratory. In this study virtual reality (VR) was used to overcome these problems in the objective psychomotor assessment of senior, junior, and novice laparoscopists. Twelve experienced laparoscopic surgeons (performed >50 Minimal Access Surgery (MAS) procedures), 12 inexperienced laparoscopic surgeons (<10 MAS procedures), and 12 laparoscopic novices (no MAS procedures) participated in the study. Each subject completed all six tasks of the Minimally Invasive Surgical Trainer; Virtual Reality (MIST VR). In comparison to the other groups, experienced laparoscopic surgeons performed the tasks significantly (p < 0.01) faster, had a lower error rate, were more economic in their movement of surgical instruments and in the use of diathermy. As a group they also showed greater consistency in their performance. MIST VR distinguished between the three groups of laparoscopists. VR provides a useful objective assessment tool for evaluating psychomotor skills for laparoscopic surgery.

Adult↗
PubMed2001

Virtual reality training leads to faster adaptation to the novel psychomotor restrictions encountered by laparoscopic surgeons.

BACKGROUND: The fulcrum effect of the body wall on instrument handling poses a major obstacle to the mastery of instrument coordination for junior laparoscopic surgeons. This study evaluated three types of laparoscopic simulator training to assess their ability to promote the user's adaptation to the fulcrum effect. METHODS: Thirty-two participants with no previous experience in laparoscopic surgery were randomly assigned to one of four groups representing different training conditions. One group was assigned to use a virtual reality simulator (MIST VR); two others were given a laparoscopic Z or U maze-tracking task. The control group received no training. Subjects were asked to perform a 2-min laparoscopic cutting task under normal laparoscopic imaging conditions first before and then after training. RESULTS: In the test trial, subjects who trained on MIST VR made significantly more correct incisions (p < 0.0001) and fewer incorrect incisions (p < 0.0001). CONCLUSION: Training on a virtual reality simulator such as MIST VR helps laparoscopic novices adapt to the fulcrum effect faster.

Clinical Competence↗
PubMed2001

Ultrasound, antisperm antibody, and hormone profiles after testicular Trucut biopsy.

OBJECTIVE: To assess the effect of Trucut needle biopsy on the ultrasound appearances of the testis in obstructive and nonobstructive azoospermia to test serum samples for antisperm antibodies and gonadotropin and testosterone levels. DESIGN: Prospective case analysis. SETTING: IVF unit. PATIENT(S): Sixteen subjects with obstructive azoospermia had postbiopsy ultrasound scans, 18 had assessment of hormone profiles, and 20 had evaluation of antisperm antibodies. INTERVENTION(S): Trucut needle testicular biopsies under local anesthetic. MAIN OUTCOME MEASURE(S): Postbiopsy testicular ultrasound, the presence of serum antisperm antibodies, and follicle stimulating and luteinizing hormone and testosterone levels. RESULT(S): There were no postbiopsy hematomas or scars, antisperm antibodies did not develop, and pituitary gonadotropins did not rise nor testosterone levels fall. CONCLUSION(S): Trucut needle testicular biopsy in men with obstructive azoospermia is not associated with defects of parenchymal structure or function.

Autoantibodies↗
PubMed2001

Cryopreservation of human semen and prepared sperm: effects on motility parameters and DNA integrity.

OBJECTIVE: To investigate effects of cryopreservation on sperm motility and DNA integrity. DESIGN: Pre-cryopreservation and post-cryopreservation analysis of motility and DNA integrity of semen and prepared sperm samples. SETTING: A hospital andrology laboratory. PATIENT(S): Forty men attending the Regional Fertility Centre, Belfast, Northern Ireland. INTERVENTION(S): Each sample was divided, and an aliquot was frozen unprepared. Remaining aliquots were prepared by Percoll density centrifugation (95.0:47.5) or direct swim-up procedure and divided into aliquots to allow direct comparison of fresh and frozen semen and prepared sperm (frozen with or without the addition of seminal plasma) from the same ejaculate. Samples were frozen by static-phase vapor cooling and being plunged into liquid nitrogen. Thawing was carried out at room temperature. MAIN OUTCOME MEASURE(S): Sperm DNA integrity was determined using a modified alkaline single cell gel electrophoresis (comet) assay, and motility was determined using computer-assisted semen analysis. RESULT(S): Sperm frozen unprepared in seminal fluid appeared more resistant to freezing damage than frozen prepared sperm. Further improvements can be achieved by selecting out the subpopulation of sperm with best motility and DNA integrity and freezing these sperm in seminal plasma, making this the optimal procedure. CONCLUSION(S): Freezing sperm in seminal plasma improves postthaw motility and DNA integrity.

Cryopreservation↗
PubMed2001

Biofilms and microbially influenced cuprosolvency in domestic copper plumbing systems.

AIMS: To survey biofilm accumulation within domestic copper plumbing pipes in South Australian drinking water distribution systems and examine its role in copper solvation (cuprosolvency). METHODS AND RESULTS: Cold water copper pipes were sampled from two different plumbing systems receiving filtered and unfiltered potable water respectively. Biomass was quantified by total organic carbon measurements and viable cell counts and microbial activity by respirometry. Biofilm accumulation was related to water chemistry within the systems, particularly nutrients, alkalinity and conductivity, as well as water turbulence. Laboratory coupon experiments were used to determine the effect of extracted biofilm on copper solvation. Biofilms were shown to be capable of both increasing and decreasing aqueous copper concentrations in comparison to sterile controls. CONCLUSIONS: The results suggest that water quality may influence the accumulation of biofilms in copper plumbing systems, as well as potential cuprosolvency activity. SIGNIFICANCE AND IMPACT OF THE STUDY: The presence of biofilms in copper plumbing systems and their ability to influence aqueous copper concentrations has implications for both public health and the management of distribution systems.

Bacteria↗
PubMed2001

Assessment of DNA integrity and morphology of ejaculated spermatozoa from fertile and infertile men before and after cryopreservation.

Cryopreservation of human spermatozoa is extensively used in artificial insemination and IVF programmes. Despite various advances in cryopreservation methodology, the recovery rate of functional post-thaw spermatozoa remains mediocre, with sperm motility being significantly decreased after freezing. This aim of this study was to investigate the effects of cryopreservation on both DNA integrity and morphology of spermatozoa from fertile and infertile men. Semen samples were obtained from 17 fertile and 40 infertile men. All samples were prepared by discontinuous Percoll density centrifugation (95.0:47.5). Samples were divided into aliquots to allow direct comparison of fresh and frozen spermatozoa from the same ejaculate. Aliquots for cryopreservation were mixed with a commercial cryoprotectant and frozen by static phase vapour cooling before plunging into liquid nitrogen. Thawing was carried out slowly at room temperature. Sperm DNA integrity was determined using a modified alkaline single cell gel electrophoresis (comet) assay and sperm morphology analysed using the Tygerberg criteria. DNA of semen and prepared spermatozoa from fertile men was found to be unaffected by cryopreservation. In marked contrast, spermatozoa from infertile men were significantly damaged by freeze-thawing. Cryopreservation had a detrimental effect on morphology of semen and prepared samples from fertile and infertile men.

Cryopreservation↗
PubMed2001

Abnormal uterine bleeding: an evaluation endometrial biopsy, vaginal ultrasound and outpatient hysteroscopy.

Abnormal uterine bleeding is a common gynaecological symptom. Whilst most patients have benign disease, thorough investigation is necessary, particularly in the peri- and post-menopausal woman. Hysteroscopy with directed biopsy of suspicious lesions is the gold standard investigation but it is invasive and is not offered in all units as an outpatient procedure. Ultrasound and outpatient biopsy techniques may allow patients to be triaged to select those who require formal evaluation by hysteroscopy. We assessed the records of 100 consecutive referrals to the outpatient hysteroscopy clinic at the Royal Maternity Hospital, Belfast. In order to develop a nomogram for the investigation of women with abnormal bleeding patterns, we compared ultrasound/biopsy diagnoses with hysteroscopy/biopsy diagnosis. Pre- and peri-menopausal patients, and post-menopausal patients taking hormone replacement therapy should be investigated further if the endometrial thickness is more than 10 mm, if endometrial biopsy is abnormal, or if symptoms are recurrent. Similarly, post-menopausal patients not taking hormone replacement therapy with an endometrial thickness of 5 mm or more should be referred for hysteroscopy.

Adult↗
PubMed2000

A comparison between randomly alternating imaging, normal laparoscopic imaging, and virtual reality training in laparoscopic psychomotor skill acquisition.

OBJECTIVES: To evaluate virtual reality as a laparoscopic training device in helping surgeons to automate to the "fulcrum effect" by comparing it to time-matched training programs using randomly alternating images (ie, y-axis inverted and normal laparoscopic) and normal laparoscopic viewing conditions. METHODS: Twenty-four participants (16 females and 8 males), were randomly assigned to minimally invasive surgery virtual reality (MIST VR), randomly alternating (between y-axis inverted and normal laparoscopic images), and normal laparoscopic imaging condition. Participants were requested to perform a 2-minute laparoscopic cutting task before and after training. RESULTS: In the test trial participants who trained on the MIST VR performed significantly better than those in the normal laparoscopic and randomly alternating imaging conditions. CONCLUSION: The results show that virtual reality training may provide faster skill acquisition with particular reference to automation of the fulcrum effect. MIST VR provides a new way of training laparoscopic psychomotor surgical skills.

Adult↗
PubMed2000

A comparison of the morphology of testicular, epididymal, and ejaculated sperm from fertile men and men with obstructive azoospermia.

OBJECTIVE: To assess the morphology of testicular, epididymal, and ejaculated sperm. DESIGN: Morphology of the three types of sperm was assessed by using Tygerberg strict criteria. SETTING: The Regional Fertility Center, Royal Maternity Hospital, Belfast, Northern Ireland, United Kingdom. PATIENT(S): Thirty-two men with obstructive azoospermia and 10 fertile men. INTERVENTION(S): Trucut needle testicular biopsy and percutaneous epididymal sperm aspiration under local anesthetic. MAIN OUTCOME MEASURE(S): Percentages of normal sperm and sperm with head, midpiece, and tail defects for testicular, epididymal, and ejaculated sperm. Testicular sperm morphology in men with obstructive azoospermia was compared with that of fertile men. RESULT(S): The percentage of normal testicular sperm (4.3%) differed significantly from the percentages of normal epididymal (10. 8%) and ejaculated sperm (9.6%). Testicular sperm morphology in men with obstructive azoospermia did not differ from that in fertile men. CONCLUSION(S): Tygerberg strict criteria are not suitable for the assessment of testicular sperm morphology.

Ejaculation↗
PubMed2000

Testicular sperm extraction by Trucut needle and milking of seminiferous tubules: a technique with high yield and patient acceptability.

OBJECTIVE: To assess the sperm yield and patient acceptability of Trucut needle testicular biopsy followed by seminiferous tubule milking. DESIGN: Prospective case analysis. SETTING: The Regional Fertility Center, Royal Maternity Hospital, Belfast, Northern Ireland, United Kingdom. PATIENT(S): Forty-one males with obstructive azoospermia (normal testicular volume and FSH and LH levels). INTERVENTION(S): Trucut needle testicular biopsies under local anesthetic with milking of the seminiferous tubules. MAIN OUTCOME MEASURE(S): Quantitation of sperm retrieved per biopsy core and patient follow-up by questionnaire. RESULT(S): A mean of 105,634 sperm (range, 5,000-427,800) were retrieved, and the mean biopsy weight was 9.17 mg. Twenty-six subjects found the biopsy painless and 15 were pain-free after biopsy. CONCLUSION(S): The Trucut needle can be used in combination with seminiferous tubule milking to obtain large numbers of sperm in men with obstructive azoospermia.

Anesthesia, Local↗
PubMed2000

Comparison of the effects of two methods of cryopreservation on testicular sperm DNA.

OBJECTIVE: To assess the effects of two methods of freezing on testicular sperm DNA from subjects with obstructive azoospermia and to compare these with samples of fresh and freeze-thawed testicular sperm from fertile men. DESIGN: The Comet assay was used to determine the percentage of undamaged DNA in fresh testicular sperm, testicular sperm freeze-thawed in suspension and in a biopsy sample (men with obstructive azoospermia), and in fresh and freeze-thawed testicular sperm (fertile men). SETTING: The Regional Fertility Center, Royal Maternity Hospital, Belfast, Northern Ireland, United Kingdom. PATIENT(S): Twelve males with obstructive azoospermia (normal testicular volume and hormone profiles) and nine fertile control subjects. INTERVENTION(S): Trucut needle testicular biopsy under local anesthetic. MAIN OUTCOME MEASURE(S): Measurement of the percentage of undamaged DNA in fresh and freeze-thawed testicular sperm using the Comet assay. RESULT(S): No significant difference was found between the percentage of undamaged DNA of fresh testicular sperm and of both types of freeze-thawed testicular sperm. There was also no significant difference between the percentage of undamaged DNA in fresh or freeze-thawed testicular sperm from controls. Control ejaculated sperm DNA was significantly more damaged than testicular sperm DNA from control men. CONCLUSION(S): Cryopreservation of testicular sperm does not increase baseline levels of DNA damage.

Biopsy↗
PubMed2000

Ovarian hyperstimulation syndrome.

Ovarian hyperstimulation syndrome is an iatrogenic complication of assisted reproduction. In its most severe form, it is potentially fatal. The major clinical components are marked ovarian enlargement and increased capillary permeability leading to ascites, hydrothorax and pericardial effusion. Severe cases are associated with thromboembolic phenomena, respiratory distress and renal failure. The definitive pathophysiology is unknown. The available evidence would support a central role for inflammatory cytokines and angiogenic growth factors. Ultrasound examination and serum oestradiol values are currently used to predict patients at risk. The ideal treatment is prevention, but there has been only limited success. The main aims of treatment are to correct fluid imbalance, maintain renal perfusion and support the patient until the condition resolves. Drug therapy has a limited role, although anticytokine agents may prove useful.

Chorionic Gonadotropin↗