Biomedical subjects

Gareth Evans

Publications and source records attributed to Gareth Evans.

At least 19 recordsLinked to original sources

PubMed2006

Assessment of in vitro sperm characteristics in relation to fertility in dairy bulls.

The performance of frozen-thawed spermatozoa from 10 Holstein bulls in a range of in vitro diagnostic tests and the relationship with adjusted in vivo fertility data was determined. The tests included an assessment of motility (subjective and computer-assisted), morphology, concentration, viability, acrosomal and chromatin integrity conducted immediately post-thaw and after swim-up, in conjunction with membrane status (CTC staining) and migration in an artificial cervical mucus. Adjusted in vivo fertility correlated with subjectively assessed post-thaw motility (r=0.672, p=0.033), post-thaw straight-line velocity (r=0.636, p=0.048), post-thaw sperm morphology (r=-0.762, p=0.010), post-thaw sperm viability (r=0.635, p=0.048), the concentration of spermatozoa after swim-up (r=0.649, p=0.042), sperm morphology after swim-up (r=-0.687, p=0.028), the number of spermatozoa migrating 10mm into artificial cervical mucus (r=0.632, p=0.050) and the distance migrated by the vanguard spermatozoon in artificial mucus (r=0.701, p=0.024). A stepwise regression analysis identified tests which, when combined, produced models with a strong correlation (R(2)>0.9) to fertility.

Acrosome↗

PubMed2006

Late toxicity is not increased in BRCA1/BRCA2 mutation carriers undergoing breast radiotherapy in the United Kingdom.

PURPOSE: To undertake the first substantial clinical study of breast radiotherapy toxicity in BRCA1 and BRCA2 mutation carriers in the United Kingdom. EXPERIMENTAL DESIGN: Acute and late radiation effects were evaluated in a retrospective study of 55 BRCA1 and BRCA2 mutation carriers treated with radiotherapy for breast cancer at four centers between 1983 and 2002. Individual matching with controls who had sporadic breast cancer was undertaken for age at diagnosis, time since completion of radiation, and treatment variables. Detailed assessments were undertaken by one examiner. Median follow-up was 6.75 years for carriers and 7.75 years for controls. Rates of late events (rib fractures, lung fibrosis, necrosis of soft tissue/bone, and pericarditis) as well as LENT-SOMA scores and clinical photography scores of breast size, shape, and skin telangiectasia were the primary end points. RESULTS: No increase in clinically significant late toxicity was seen in the mutation carriers. CONCLUSIONS: These data add substantial weight to the evidence that the outcomes in the treated breast from radiotherapy in women with BRCA1 or BRCA2 mutations are comparable with those in women with sporadic breast cancer.

Adult↗

PubMed2006

Acute chemotherapy-related toxicity is not increased in BRCA1 and BRCA2 mutation carriers treated for breast cancer in the United Kingdom.

PURPOSE: To evaluate acute toxicity induced by chemotherapy for breast cancer in a retrospective study of 62 BRCA1/2 mutation carriers matched 1:1 with women who had treatment for sporadic disease in the United Kingdom between 1983 and 2003. EXPERIMENTAL DESIGN: All participants were interviewed by one of two researchers using standardized questionnaires, and their medical records were reviewed by one research nurse. The two main regimens received were cyclophosphamide, methotrexate, and fluorouracil and fluorouracil, epirubicin, and cyclophosphamide. The proportion of cases and controls receiving anthracycline-based treatment was equivalent, but fewer BRCA1 cases received this treatment than did BRCA2 mutation carriers. Toxicity was documented using the Eastern Cooperative Oncology Group Common Toxicity Criteria for hematologic, infective, and gastrointestinal toxicities. No increase in toxicity was seen in BRCA1/2 mutation carriers. RESULTS: The only significant difference was that neutropenia was less evident in BRCA2 mutation carriers than in either BRCA1 mutation carriers or controls. As a result, there was no requirement for dose reduction among BRCA2 mutation carriers, in contrast to 10 of 39 BRCA1 carriers and 16 of 62 controls (P = 0.02). CONCLUSIONS: This result has implications for therapy and indicates that women with mutations in BRCA1 and BRCA2 may be given the same doses of chemotherapy as noncarriers.

Adult↗

PubMed2006

Effect of seminal plasma fractions from entire and vasectomized rams on the motility characteristics, membrane status, and in vitro fertility of ram spermatozoa.

Whole seminal plasma from ram semen collected before and after vasectomy was separated into 2 fractions, supernatant and pellet of vesicles, and their protein profiles characterized by one-dimensional (1D) gel electrophoresis. The effects of autologous whole seminal plasma and these fractions on motility characteristics (assessed subjectively and by computer-assisted sperm analysis), membrane status (assessed by chlortetracycline staining patterns), and in vitro fertility (assessed by fertilization success and timing of fertilization events) of washed frozen-thawed ram spermatozoa were studied. Regardless of vasectomy, whole seminal plasma and supernatant displayed similar protein patterns. These fractions, when included in the postthaw buffer, improved the motility characteristics (59.6% +/- 6.21% and 39.6% +/- 6.21% vs 31.7% +/- 6.46% and 15.5% +/- 6.46% total motility) and membrane integrity (36.6% +/- 8.52% and 31.2% +/- 8.19% vs 30.3% +/- 11.49% and 21.6% +/- 10.28% B staining pattern [characteristic of capacitated acrosome-intact cells] for whole seminal plasma and supernatant vs control at 3 and 6 hours of postthaw incubation, respectively) of frozen-thawed spermatozoa and improved their ability to fertilize in vitro-matured oocytes compared with control buffer without seminal plasma fractions (25.3%, 47.4%, and 37.4% vs 12.3%, 20.2%, and 20.5% oocytes fertilized for spermatozoa incubated with supernatant vs control at 2, 6, and 18 hours after insemination, respectively). Vesicles were absent from semen collected after vasectomy. Pellets of vesicles collected before vasectomy had no effect on spermatozoa at their normal protein concentration but marginally improved both motility characteristics and in vitro fertility, possibly due to contamination from supernatant proteins, when their concentration in the postthaw medium was increased by threefold. It was concluded that the vesicle-free supernatant fraction of seminal plasma, but not the seminal plasma membrane vesicles, improved the function and fertility of frozen-thawed ram spermatozoa when added to the postthaw medium.

Animals↗

PubMed2006

Evidence for a colorectal cancer susceptibility locus on chromosome 3q21-q24 from a high-density SNP genome-wide linkage scan.

To identify a novel susceptibility gene for colorectal cancer (CRC), we conducted a genome-wide linkage analysis of 69 pedigrees segregating colorectal neoplasia in which involvement of known loci had been excluded, using a high-density single nucleotide polymorphism (SNP) array containing 10,204 markers. Multipoint linkage analyses were undertaken using both non-parametric (model-free) and parametric (model-based) methods. After the removal of SNPs in strong linkage disequilibrium, we obtained a maximum non-parametric linkage statistic of 3.40 (P=0.0003) at chromosomal region 3q21-q24. The same genomic position also yielded the highest multipoint heterogeneity LOD (HLOD) score under a dominant model (HLOD=3.10, genome-wide P=0.038) with 62% of families linked to the locus. We provide evidence for a novel CRC susceptibility gene. Further studies are needed to confirm this localization and to evaluate the contribution of this locus to disease incidence.

Chromosome Mapping↗

PubMed2006

Effect of chest X-rays on the risk of breast cancer among BRCA1/2 mutation carriers in the international BRCA1/2 carrier cohort study: a report from the EMBRACE, GENEPSO, GEO-HEBON, and IBCCS Collaborators' Group.

PURPOSE: Women who carry germline mutations in the BRCA1 and BRCA2 genes are at greatly increased risk of breast cancer (BC). Numerous studies have shown that moderate to high doses of ionizing radiation are a risk factor for BC. Because of the role of the BRCA proteins in DNA repair, we hypothesized that BRCA carriers might be more sensitive to ionizing radiation than women in the general population. PATIENTS AND METHODS: A retrospective cohort study of 1,601 female BRCA1/2 carriers was performed. Risk of breast cancer from exposure to chest x-rays, as assessed by questionnaire data, was analyzed using a weighted Cox proportional hazards model. RESULTS: In this cohort, any reported exposure to chest x-rays was associated with an increased risk of BC (hazard ratio [HR] = 1.54; P = .007). This risk was increased in carrier women aged 40 years and younger (HR = 1.97; P < .001) and in women born after 1949 (HR = 2.56; P < .001), particularly those exposed only before the age of 20 years (HR = 4.64; P < .001). CONCLUSION: In our series of BRCA carriers, we detected a relatively large effect on BC risk with a level of radiation exposure that is at least an order of magnitude lower than in previously studied medical radiation-exposed cohorts. Although part of this increase may be attributable to recall bias, the observed patterns of risk in terms of age at exposure and attained age are consistent with those found in previous studies. If confirmed, the results have important implications for the use of x-ray imaging in young BRCA1/2 carriers.

Adult↗

PubMed2006

Pregnancies, breast-feeding, and breast cancer risk in the International BRCA1/2 Carrier Cohort Study (IBCCS).

BACKGROUND: Multiparity, young age at first childbirth, and breast-feeding are associated with a reduced risk of breast cancer in the general population. The breast cancer predisposition gene, BRCA1, regulates normal cell differentiation. Because mammary gland cells divide and differentiate during pregnancy, reproductive factors may influence breast cancer risk in BRCA1/2 mutation carriers differently than they do in noncarriers. METHODS: We performed a retrospective cohort study of 1601 women in the International BRCA1/2 Carrier Cohort Study cohort, all of whom carried a mutation in BRCA1 or BRCA2. Information on reproductive factors was obtained from a questionnaire. At the time of interview 853 subjects were classified with breast cancer. Data were analyzed by using a weighted cohort approach. All statistical tests were two-sided. RESULTS: There was no statistically significant difference in the risk of breast cancer between parous and nulliparous women. Among parous women, an increasing number of full-term pregnancies was associated with a statistically significant decrease in the risk of breast cancer (Ptrend = .008); risk was reduced by 14% (95% confidence interval [CI] = 6% to 22%) for each additional birth. This association was the same for carriers of mutations in either BRCA1 or BRCA2 and was restricted to women older than 40 years. In BRCA2 mutation carriers, first childbirth at later ages was associated with an increased risk of breast cancer compared with first childbirth before age 20 years (20-24 years, hazard ratio [HR] = 2.33 [95% CI = 0.93 to 5.83]; 25-29 years, HR = 2.68 [95% CI = 1.02 to 7.07]; > or = 30 years, HR = 1.97 [95% CI = 0.67 to 5.81]), whereas in BRCA1 mutation carriers, first childbirth at age 30 years or later was associated with a reduced risk of breast cancer compared with first childbirth before age 20 years (HR = 0.58 [95% CI = 0.36 to 0.94]). Neither history of interrupted pregnancies (induced abortions or miscarriage) nor history of breast-feeding was statistically significantly associated with the risk of breast cancer. CONCLUSIONS: BRCA1 and BRCA2 mutation carriers older than 40 years show a similar reduction in breast cancer risk with increasing parity as non-carriers.

Abortion, Induced↗

PubMed2006

Mortality after bilateral salpingo-oophorectomy in BRCA1 and BRCA2 mutation carriers: a prospective cohort study.

BACKGROUND: Bilateral prophylactic salpingo-oophorectomy (BPSO) is used widely used to reduce the risk of breast and ovarian cancer in women with BRCA1 and BRCA2 mutations. However, the reduction in mortality after this surgery is unclear. We aimed to assess whether BPSO improves overall mortality or cancer-specific mortality in BRCA1 and BRCA2 mutation carriers. METHODS: We identified a prospective cohort of 666 women with disease-associated germline mutations in BRCA1 or BRCA2 and no previous cancer diagnosis. In our primary analysis, we compared 155 women who had had BPSO and 271 women matched for age at BPSO who had not had BPSO. In our secondary analysis, we compared 188 women who had had BPSO with 478 women who had not. In both analyses, we compared overall mortality and cancer-specific mortality. All analyses were adjusted for centre, mutation (BRCA1 vs BRCA2), and birth year. FINDINGS: In the primary analysis, mean follow-up from BPSO to censoring was 3.1 years [SD 2.4] in the BPSO group and 2.1 years [2.0] in the non-BPSO group. The hazard ratio (HR) for overall mortality was 0.24 (95% CI 0.08-0.71), for breast-cancer-specific mortality was 0.10 (0.02-0.71), and for ovarian-cancer-specific mortality was 0.05 (0.01-0.46) for women who had BPSO compared with those who had not. In secondary analysis, BPSO was associated with reduced overall mortality (HR 0.28 [95% CI 0.10-0.74]), but not with breast-cancer-specific mortality (0.15 [0.02-1.18] or ovarian-cancer-specific mortality (0.23 [0.02-1.87]. When regarded as a time-dependent covariate, BPSO was not associated significantly with mortality. INTERPRETATION: If confirmed, the finding that BPSO improves overall survival and cancer-specific survival in women with BRCA mutations will complement our existing knowledge of cancer-risk reduction associated with BPSO. Together, these data could give information to women who are considering genetic testing.

Adult↗

PubMed2005

In vitro and in vivo survival of bisected sheep embryos derived from frozen-thawed unsorted, and frozen-thawed sex-sorted and refrozen-thawed ram spermatozoa.

Ovine IVP embryos were derived from frozen-thawed unsorted and frozen-thawed sex-sorted spermatozoa that had been refrozen and thawed. The embryos were bisected and cultured in vitro, or transferred to recipient ewes to determine their survival in vitro and in vivo. Oocyte progression to the blastocyst stage was similar for unsorted (97/232, 41.8%) and sex-sorted spermatozoa (113/286, 39.5%; P > 0.05). Embryo survival in vitro post-bisection was similar for demi-embryos derived from unsorted and sex-sorted sperm, and embryos bisected at the blastocyst and expanded blastocyst stage (P > 0.05). A higher proportion of recipient ewes were pregnant at Day 63 after transfer of two intact embryos derived from unsorted (17/21, 80.9%) than two demi-embryos derived from unsorted (5/15, 33.3%) or sex-sorted spermatozoa (7/17, 41.2%). The number of fetuses per original embryo at Day 63 did not differ among groups (unsorted intact: 23/42, 54.8%; unsorted demi: 7/15, 46.7%; sex-sorted demi: 10/17, 58.8%) and twin pregnancies were observed in all groups. Embryo survival to term was high, and was not significantly different among intact (unsorted: 22/42, 52.4%) and demi-embryos (unsorted: 4/15, 26.7%; sex-sorted spermatozoa: 7/17, 41.2%; P > 0.05). Dizygotic twins (n = 6 sets) were born after the transfer of two intact embryos derived from unsorted spermatozoa, but only singleton lambs resulted from the transfer of demi-embryos. In conclusion, bisected IVP embryos successfully developed into morphologically normal lambs. However, embryo survival to term was neither increased nor decreased by embryo bisection.

Animals↗

PubMed2005

The perceptions of occupational health in primary care.

AIM: A random sample of general practitioners (GPs), practice nurses (PNs) and practice managers (PMs) in Sheffield and Manchester was recruited into a study to evaluate the perceptions of occupational health (OH) in primary care. METHODS: Qualitative data were collected using focus groups with three groups of primary care sector professionals. Quantitative data were collected nationally from 295 GPs using a postal questionnaire. RESULTS: GPs and PNs had minimal OH training, and 60% of GPs reported constraints in addressing OH matters with patients. The lack of referral routes (63 and 67%, respectively) was also seen as a barrier. OH was regarded as a speciality, and primary care professionals preferred to refer patients with OH problems to specialist centres because they perceived barriers to their dealing with the issues. A total of 74% of GPs surveyed thought that speedier access to secondary care would help them to address OH problems. CONCLUSIONS: This study has identified some of the problems associated with delivering OH through primary care. It also demonstrated a need for greater emphasis on OH education in medical and nurse training, and a need for better advice for GPs, PNs and PMs regarding support services for OH.

Adult↗

PubMed2005

The effect of gamete co-incubation time during in vitro fertilization with frozen-thawed unsorted and sex-sorted ram spermatozoa on the development of in vitro matured adult and prepubertal ewe oocytes.

In vitro matured adult (Experiment 1) and prepubertal (Experiment 2) ewe oocytes were co-incubated with unsorted or sex-sorted frozen-thawed spermatozoa for 2 to 3 h (short) or 18 to 20 h (long) to determine the effects of reducing the gamete co-incubation time during IVF on subsequent embryonic development in vitro. For oocytes derived from adult ewes, there were no differences in oocyte fertilization and cleavage at 24 h post insemination (hpi) between types of spermatozoa or co-incubation times (P > 0.05). By 48 hpi, oocyte cleavage was higher after a short (390/602, 64.8%) compared with a long (381/617, 61.7%) co-incubation (P < 0.05), and was not significantly different for unsorted (266/372, 71.5%) and sex-sorted (505/849, 59.9%) spermatozoa. Blastocyst formation from cleaved oocytes was similar for unsorted (150/266, 56.4%) and sex-sorted (295/505, 58.4%) spermatozoa, but was higher after a short (240/390, 61.5%) than long (205/381, 53.8%) co-incubation (P < 0.05). Oocyte development to the blastocyst stage was not different for unsorted (150/372; 40.3%) and sex-sorted (295/847; 34.8%) spermatozoa but was significantly increased by a short (240/602, 39.9%) compared with a long (205/617, 33.2%) co-incubation. Fertilization of oocytes from prepubertal ewes was similar for types of spermatozoa and for duration of co-incubation. Oocyte cleavage (48 hpi) was similar for a short (241/377, 63.9%) and long (226/349, 64.8%) co-incubation with unsorted spermatozoa, but was increased (P < 0.05) by a long co-incubation (286/500, 57.2% versus 163/517, 31.5%) with sex-sorted spermatozoa. Blastocyst formation from cleaved oocytes was similar for unsorted (230/467, 49.3%) and sex-sorted (186/449, 41.4%) spermatozoa, and a short (200/404, 49.5%) or long (216/512, 42.1%) co-incubation. However, oocyte development to the blastocyst stage was higher (P < 0.05) after IVF with unsorted (230/726, 37.1%) than sex-sorted (186/1017, 18.3%) spermatozoa. Reducing the duration of gamete co-incubation did not deleteriously affect the in vitro development of adult and prepubertal ewe derived oocytes after IVF with unsorted and sex-sorted spermatozoa. In general, sex-sorting had no substantial influence on fertilization and embryo development rates.

Animals↗

PubMed2005

Prediction of BRCA1 status in patients with breast cancer using estrogen receptor and basal phenotype.

PURPOSE: To investigate the proportion of breast cancers arising in patients with germ line BRCA1 and BRCA2 mutations expressing basal markers and developing predictive tests for identification of high-risk patients. EXPERIMENTAL DESIGN: Histopathologic material from 182 tumors in BRCA1 mutation carriers, 63 BRCA2 carriers, and 109 controls, collected as part of the international Breast Cancer Linkage Consortium were immunohistochemically stained for CK14, CK5/6, CK17, epidermal growth factor receptor (EGFR), and osteonectin. RESULTS: All five basal markers were commoner in BRCA1 tumors than in control tumors (CK14: 61% versus 12%; CK5/6: 58% versus 7%; CK17: 53% versus 10%; osteonectin: 43% versus 19%; EGFR: 67% versus 21%; P < 0.0001 in each case). In a multivariate analysis, CK14, CK5/6, and estrogen receptor (ER) remained significant predictors of BRCA1 carrier status. In contrast, the frequency of basal markers in BRCA2 tumors did not differ significant from controls. CONCLUSION: The use of cytokeratin staining in combination with ER and morphology provides a more accurate predictor of BRCA1 mutation status than previously available, that may be useful in selecting patients for BRCA1 mutation testing. The high percentage of BRCA1 cases positive for EGFR suggests that specific anti-tyrosine kinase therapy may be of potential benefit in these patients.

Biomarkers, Tumor↗

PubMed2005

In vitro and in vivo developmental capabilities and kinetics of in vitro development of in vitro matured oocytes from adult, unstimulated and hormone-stimulated prepubertal ewes.

The in vitro and in vivo developmental capabilities and kinetics of in vitro development of embryos derived from adult ewes and from unstimulated (16- to 24-week-old) and hormone-stimulated prepubertal (3- to 5-week-old) ewes were assessed. Cleavage was lower for hormone-stimulated (617/1025; 60.2%) than unstimulated prepubertal (117/169; 69.2%) and adult ewe oocytes (184/267; 68.9%; P < 0.05). Blastocyst formation by Day 7 (from zygotes) was similar for unstimulated (45/117; 38.5%), hormone-stimulated prepubertal (229/617; 37.1%) and adult ewes (101/184; 54.9%). Blastocysts derived from hormone-stimulated prepubertal ewes developed mainly on day 7, compared with Day 6 for adult and unstimulated prepubertal ewes. Pregnancy rates (day 60) and embryonic loss (between Days 20 and 60) did not differ after transfer to adult recipient ewes of adult, unstimulated and hormone-stimulated prepubertal-derived fresh or frozen-thawed embryos. The number of lambs born as a proportion of embryos transferred did not differ for fresh and frozen embryos derived from adult ewes (3/16; 18.8% and 1/12; 8.3%, respectively) and unstimulated prepubertal lambs (2/6; 33.3%, and 1/10; 10.0%, respectively), but was higher for fresh than frozen embryos from hormone-stimulated prepubertal ewes (7/16; 43.8%, and 2/14; 14.3%, respectively; P < 0.05). There were high rates of in vitro and in vivo development of oocytes from 3- to 5-week-old lambs, but in vitro development was lower than with oocytes from adult ewes. However, the speed of embryonic development in vitro and the in vivo development of fresh and frozen embryos were similar to those derived from adult and unstimulated prepubertal ewes. The present results were an improvement in the efficiency of producing embryos and offspring from hormone-stimulated 3- to 5-week-old lambs.

Animals↗

PubMed2005

Flow cytometric evaluation of sperm parameters in relation to fertility potential.

Most laboratory methods used to evaluate semen quality have not correlated highly with fertilizing capacity. The discovery of a variety of fluorochromes and compounds conjugated to fluorescent probes has enabled a more widespread analysis of sperm attributes, and in conjunction with the flow cytometer, permit the evaluation of a large number of spermatozoa. A number of characteristics of sperm integrity, viability and function can be assessed by flow cytometry. The DNA status of spermatozoa has been determined using the metachromatic properties of acridine orange (AO). AO staining, when used in the sperm chromatin structure assay (SCSA), correlates with fertility in a number of species. DNA fragmentation can also be assessed using the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay, which identifies DNA strand breaks by labeling free 3'-OH termini with modified nucleotides. The status of the sperm acrosome can be determined using fluorescently labeled lectins and LysoTracker Green DND-26, a fluorescent acidotropic probe. Capacitation status has been observed through calcium-mediated changes using chlortetracycline (CTC) or by changes in membrane fluidity monitored by the binding of the fluorescent amphiphilic probe, Merocyanine 540. Fluorescently labeled annexin-V, C6NBD and Ro-09-0198 can also be used to detect changes in membrane phospholipid distribution. Cell viability can be determined using the propensity of propidium iodide (PI), ethidium homodimer-1 (EthD-1) or Yo-Pro-1 to permeate damaged membranes. These are generally more adaptable to clinical flow cytometry than the bisbenzimide membrane impermeable stain, Hoechst 33258, which excites in the ultraviolet range and requires UV laser equipment. Mitochondrial function can be determined using rhodamine 123 (R123) and MitoTracker Green FM (MITO) and 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolyl-carbocyanine iodide (JC-1). Flow cytometry is a tool that may be used in the future to monitor many new potential markers of sperm function.

Acrosome↗

PubMed2005

Flow cytometric sorting of non-human primate sperm nuclei.

Pre-determination of the sex of offspring has implications for management and conservation of captive wildlife species, particularly those with single sex-dominated social structures. Our goal is to adapt flow cytometry technology to sort spermatozoa of non-human primate species for use with assisted reproductive technologies. The objectives of this study were to: (i) determine the difference in DNA content between X- and Y-bearing spermatozoa (ii) sort sperm nuclei into X- and Y-enriched samples; and (iii) assess the accuracy of sorting. Spermatozoa were collected from two common marmosets (Callithrix jacchus), seven hamadryas baboons (Papio hamadryas) and two common chimpanzees (Pan troglodytes). Human spermatozoa from one male were used as a control. Sperm nuclei were stained (Hoechst 33342), incubated and analyzed using a high-speed cell sorter. Flow cytometric reanalysis of sorted samples (sort reanalysis, 10,000 events/sample) and fluorescence in situ hybridization (FISH; 500 sperm nuclei/sample) were used to evaluate accuracy of sorting. Based on fluorescence intensity of X- and Y-bearing sperm nuclei, the difference in DNA content between X and Y populations was 4.09 +/- 0.03, 4.20 +/- 0.03, 3.30 +/- 0.01, and 2.97 +/- 0.05%, for marmoset, baboon, chimpanzee and human, respectively. Sort reanalysis and FISH results were similar; combined data revealed high levels of purity for X- and Y-enriched samples (94 +/- 0.9 and 93 +/- 0.8%, 94 +/- 0.7 and 94 +/- 0.5%, 91 +/- 0.9 and 97 +/- 0.6%, 94 +/- 0.6 and 94 +/- 0.9%, for marmoset, baboon, chimpanzee and human, respectively). These data indicate the potential for high-purity sorting of spermatozoa from non-human primates.

Animals↗

PubMed2005

Effects of lamb age, hormone stimulation and response to hormone stimulation on the yield and in vitro developmental competence of prepubertal lamb oocytes.

Experiments were conducted to determine the effects of lamb age, hormone stimulation (Experiment 1) and response to stimulation (Experiment 2) on the in vitro production of embryos from prepubertal lambs aged 3-4 and 6-7 weeks of age. For 3-4-week-old lambs, hormone stimulation increased the number of follicles (29.9 +/- 15.3 v. 70.6 +/- 8.2), oocytes per ovary (18.3 +/- 6.3 v. 39.3 +/- 5.8) and oocyte development to the blastocyst stage (0/192 (0.0%) v. 115/661 (17.4%); P < 0.05). Lamb age (3-4 v. 6-7 weeks old) increased oocyte development to the blastocyst stage (115/661 (17.4%) v. 120/562 (21.4%) respectively). In Experiment 2, hormone-stimulated lambs (3-4 and 6-7 weeks old) were divided into low, medium or high responders based on the number of ovarian follicles (<20, 20-50 and >100 follicles per ovary respectively). The response to hormone stimulation did not affect oocyte recovery rate, but the number of oocytes suitable for culture was increased for high-responding 3-4-week-old lambs only (P < 0.05). Oocyte development to the blastocyst stage was not affected by response to stimulation for 3-4-week-old lambs (15.2-25.6%; P > 0.05), but was reduced for high (6.7%) compared with low (19.5%) and medium (30.9%) responding 6-7-week-old lambs (P < 0.05). These results demonstrate that the production of embryos from prepubertal lambs is increased by hormone stimulation and lamb age and the response to stimulation does not affect embryo production from 3-4-week-old lambs, although by 6-7 weeks of age a high response to stimulation reduces blastocyst formation.

Animals↗

PubMed2005

Spinal tumors in neurofibromatosis type 2. Is emerging knowledge of genotype predictive of natural history?

OBJECT: The authors conducted a study to examine the incidence, classification, and progression of spinal tumors in patients with neurofibromatosis Type 2 (NF2) treated at a single center, and to examine relationships with the known mutational subtypes of NF2. METHODS: They performed a retrospective review of clinical records, neuroimaging studies, and genetic data obtained in 61 patients with NF2. Forty-one (67%) of 61 patients harbored one or more spinal tumors. Thirty-four patients had undergone serial spinal magnetic resonance imaging during a mean follow-up period of 52 months (range 10-103 months; median 53 months). In 16 patients there were multiple extramedullary tumors smaller than 5 mm, which did not progress. Fourteen patients harbored at least one extramedullary tumor that was greater than 5 mm; of these, radiological progression was demonstrated or spinal tumor excision was performed during the follow-up period in eight cases (57%). Eleven patients harbored intramedullary cord tumors in addition to small and large extramedullary tumors, three (27%) of which exhibited radiological progression. In cases in which genotypes were known, protein-truncating mutations were significantly more likely to be associated with the presence of spinal tumors than in other types (p = 0.03, Fisher exact test). No associations between clinical behavior of spinal tumors and genotype, however, could be demonstrated. CONCLUSIONS: Spinal tumors in cases involving NF2 are heterogeneous in type, distribution, and behavior but larger-size tumors are more likely to progress significantly. Intramedullary tumors usually accompany multiple extramedullary tumors. In the authors' experience subtyping of the NF2 mutation has not yet influenced management. Protein-truncating mutations are associated with an increased prevalence of spinal tumors.

Adolescent↗

PubMed2004

Eight novel MSH6 germline mutations in patients with familial and nonfamilial colorectal cancer selected by loss of protein expression in tumor tissue.

Germline mutations in mismatch repair (MMR) genes, predominantly in MLH1 and MSH2, are responsible for hereditary nonpolyposis colorectal cancer (HNPCC), a cancer-susceptibility syndrome with high penetrance. In addition, MSH6 mutations have been reported to account for about 10% of all germline mismatch repair (MMR) gene mutations in HNPCC patients, and have been associated with a later age of onset of the disease compared to MLH1 and MSH2 mutations. Here, we report eight novel germline mutations in MSH6. The patients were selected by having developed tumors with loss of MSH6 protein expression. All tumors showed high-level microsatellite instability (MSI-H). Seven mutations resulted in premature stop codons, comprised of two nonsense mutations (c.426G>A [p.W142X], c.2105C>A [p.S702X]), two insertions (c.2611_2614dupATTA [p.I872fsX10], c.3324dupT [p.I1109fsX3]) and three deletions (c.1190_1191delAT [p.Y397fsX3], c.1632_1635delAAAA [p.E544fsX26], c.3513_3514delTA [p.1171fsX5]). In addition, an amino acid substitution of an arginine residue (c.2314C>T [p.R772W]) conserved throughout a wide variety of mutS homologs has been found in a patient not fulfilling the Bethesda criteria for HNPCC. Our results emphasize the suitability of IHC as a pre-selection tool for MSH6 mutation analysis and the high frequency of germline mutation detection in patients with MSH6-deficient tumors. In addition, our findings point towards a broad variability regarding penetrance associated with MSH6 germline mutations.

Adult↗