Analysis of radon mitigation methods: 10-year review.

Exposure to the radon gas within a building can result in an increased risk of lung cancer. To minimise the health risk, indoor radon concentrations can be reduced using well-established mitigation methods. The performance of various radon reduction methods, their combination as well as other factors that can impact the efficiency of radon mitigation, were analysed using data collected from approximately 2,800 dwellings that had installed radon mitigation techniques during the period 2007 to 2017. As demonstrated previously (Hodgson 2011), active methods are the most effective at reducing high concentrations of radon to below the Action and Target Levels (200 Bq m-3 and 100 Bq m-3 respectively). Reduction factors of up to 5.5 using single active methods and 8.3 using a combination of active methods were estimated in this study. For indoor radon levels greater than 1,000 Bq m-3, the Active Sump remained the most efficient technique, with the Active Underfloor Ventilation being the second most effective method. Passive methods alone or in combination with other passive methods offered moderate reductions at high radon concentration. Of the passive methods, Underfloor Ventilation was found to have the highest performance with a reduction factor of 1.8. The conclusions of this study should be used to update guidance for stakeholders including householders, contractors, radon awareness campaigns and the UKradon.org website.

Accelerometer-based prediction of skeletal mechanical loading during walking in normal weight to severely obese subjects.

There is no objective way to monitor mechanical loading characteristics during exercise for bone health improvement. We developed accelerometry-based equations to predict ground reaction force (GRF) and loading rate (LR) in normal weight to severely obese subjects. Equations developed had a high and moderate accuracy for GRF and LR prediction, respectively, thereby representing an accessible way to determine mechanical loading characteristics in clinical settings. INTRODUCTION: There is no way to objectively prescribe and monitor exercise for bone health improvement in obese patients based on mechanical loading characteristics. We aimed to develop accelerometry-based equations to predict peak ground reaction forces (pGRFs) and peak loading rate (pLR) on normal weight to severely obese subjects. METHODS: Sixty-four subjects (45 females; 84.6 ± 21.7 kg) walked at different speeds (2-6 km·h-1) on a force plate-equipped treadmill while wearing accelerometers at lower back and hip. Regression equations were developed to predict pGRF and pLR from accelerometry data. Leave-one-out cross-validation was used to calculate prediction accuracy and Bland-Altman plots. Actual and predicted values at different speeds were compared by repeated measures ANOVA. RESULTS: Body mass and peak acceleration were included for pGRF prediction and body mass and peak acceleration transient rate for pLR prediction. All pGRF equation coefficients of determination were above 0.89, a good agreement between actual and predicted pGRFs, with a mean absolute percent error (MAPE) below 6.7%. No significant differences were observed between actual and predicted pGRFs at each walking speed. Accuracy indices from our equations were better than previously developed equations for normal weight subjects, namely a MAPE approximately 3 times smaller. All pLR prediction equations presented a lower accuracy compared to those developed to predict pGRF. CONCLUSION: Walking pGRF and pLR in normal weight to severely obese subjects can be predicted with moderate to high accuracy by accelerometry-based equations, representing an easy and accessible way to determine mechanical loading characteristics in clinical settings.

A major advance of tropical Andean glaciers during the Antarctic cold reversal.

The Younger Dryas stadial, a cold event spanning 12,800 to 11,500 years ago, during the last deglaciation, is thought to coincide with the last major glacial re-advance in the tropical Andes. This interpretation relies mainly on cosmic-ray exposure dating of glacial deposits. Recent studies, however, have established new production rates for cosmogenic (10)Be and (3)He, which make it necessary to update all chronologies in this region and revise our understanding of cryospheric responses to climate variability. Here we present a new (10)Be moraine chronology in Colombia showing that glaciers in the northern tropical Andes expanded to a larger extent during the Antarctic cold reversal (14,500 to 12,900 years ago) than during the Younger Dryas. On the basis of a homogenized chronology of all (10)Be and (3)He moraine ages across the tropical Andes, we show that this behaviour was common to the northern and southern tropical Andes. Transient simulations with a coupled global climate model suggest that the common glacier behaviour was the result of Atlantic meridional overturning circulation variability superimposed on a deglacial increase in the atmospheric carbon dioxide concentration. During the Antarctic cold reversal, glaciers advanced primarily in response to cold sea surface temperatures over much of the Southern Hemisphere. During the Younger Dryas, however, northern tropical Andes glaciers retreated owing to abrupt regional warming in response to reduced precipitation and land-surface feedbacks triggered by a weakened Atlantic meridional overturning circulation. Conversely, glacier retreat during the Younger Dryas in the southern tropical Andes occurred as a result of progressive warming, probably influenced by an increase in atmospheric carbon dioxide. Considered with evidence from mid-latitude Andean glaciers, our results argue for a common glacier response to cold conditions in the Antarctic cold reversal exceeding that of the Younger Dryas.

The effect of a physical activity consultation on body mass index z-score of overweight adolescents: results from a pediatric outpatient obesity clinic.

Physical activity (PA) is recognized as having many health benefits. Despite of all the efforts, the majority of the overweight adolescents still present low levels of PA. PA consultation can be a cost-effective way of enhancing PA and improve weight status among overweight adolescents. The main aim of this study was to analyze whether adolescents attending a PA consultation in a clinical setting show more therapeutic success at 6 months, based on body mass index (BMI) z-score and waist circumference (WC), compared to those only followed by the pediatrician and nutritionist. Clinical records from 396 patients were analyzed: PA consultation (PAc) group, n = 198; standard consultation (STc) group, n = 198. Baseline differences between groups were analyzed using chi-square and independent sample t tests. Changes within groups and between groups were analyzed using paired sample t tests and independent sample t tests, respectively. Patients in both groups decreased their BMI z-score. The PAc has shown a higher decrease in the BMI z-score (PAc -0.12, p < 0.0001; STc -0.05, p < 0.0001). The WC of the PAc group has increased 2.2 cm less than the one of the STc group (p < 0.005). The difference in waist-to-height ratio between the PAc and STc groups was of 0.015 (p < 0.005), showing a trend to decrease in the PAc group (-0.005, p = 172). CONCLUSION: Although the success of adolescent obesity management cannot be based only on BMI, a PA consultation on the top of the traditional pediatric and nutrition interventions may further improve the BMI z-score outcome at 6 months. What is Known: • Physical activity (PA) plays an important role in weight management. However, most adolescents, in particular those who are overweight, present low levels of PA. • There is no consensus whether PA counseling influences PA behavior. What is New: • A PA consultation (a structured form of PA counseling) as part of a multidisciplinary team may further be useful for weight management of overweight adolescents followed at the clinical setting, compared to the traditional approach including only the pediatric and nutrition consultations. • Waist-to-height ratio may be more suitable than waist circumference per se to track changes in abdominal adiposity among adolescents who are still growing.

Effects of doxorubicin administration on bone strength and quality in sedentary and physically active Wistar rats.

Doxorubicin (DOX) is used in pediatric cancer treatment. This study assessed the effects of 7 weeks of DOX and 10-week recovery on bone quality and biomechanical properties in sedentary and exercised Wistar rats. DOX decreases femur diaphysis radial growth and biomechanical properties. Some of these DOX effects were aggravated by exercise. INTRODUCTION: Bone growth in pre-pubertal years critically influences adult fracture risk. DOX is widely used in the treatment of pediatric cancers, but there is limited evidence on its potential negative effects on bone growth. Exercise improves bone growth in children, but there is no evidence if it protects against DOX-induced bone toxicity. This study investigates the early and intermediate effects of a 7-week course of DOX on bone histomorphometry and strength in sedentary and exercised growing animal models. METHODS: Sixty-eight male Wistar rats (8 weeks) were treated with DOX (2 mg kg-1) or vehicle for 7 weeks and afterward housed in standard cages or in cages with a running wheel and killed 2 or 10 weeks after last DOX administration. Femurs and blood were collected for assaying geometry, trabecular microarchitecture (histology), biomechanical properties (three-point bending and shearing of the femoral neck), bone calcium content and density (atomic absorption spectroscopy), and bone turnover markers (ELISA). RESULTS: DOX treatment reduced the femur diaphysis radial growth, with DOX-treated animals having a lower tissue area, cortical area, cortical thickness, and moment of inertia. DOX also decreased distal femur trabecular bone volume and trabecular number and increased trabecular separation. Femur diaphysis stiffness and maximum load were also reduced in past DOX-treated animals. Exercise was shown to worsen the effects of past DOX treatment on the femur diaphysis mechanical properties. CONCLUSION: DOX negatively affects bone geometry, trabecular microarchitecture, and femur mechanical properties in growing Wistar rats. Exercise further aggravates the detrimental effects of past DOX treatment on bone mechanical properties.

Retrospective study of the medium-chain acyl-CoA dehydrogenase deficiency in Portugal.

Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is the commonest genetic defect of mitochondrial fatty acid ß-oxidation. About 60% of MCADD patients are homozygous for the c.985A>G (p.Lys329Glu) mutation in the ACADM gene (G985 allele). Herein, we present the first report on the molecular and biochemical spectrum of Portuguese MCADD population. From the 109 patients studied, 83 were diagnosed after inclusion of MCADD in the national newborn screening, 8 following the onset of symptoms and 18 through segregation studies. Gypsy ancestry was identified in 85/109 patients. The G985 allele was found in homozygosity in 102/109 patients, in compound heterozygosity in 6/109 and was absent in one patient. Segregation studies in the Gypsy families showed that 93/123 relatives were carriers of the G985 allele, suggesting its high prevalence in this ethnic group. Additionally, three new substitutions-c.218A>G (p.Tyr73Cys), c.503A>T (p.Asp168Val) and c.1205G>T (p.Gly402Val)-were identified. Despite the particularity of the MCADD population investigated, the G985 allele was found in linkage disequilibrium with H1(112) haplotype. Furthermore, two novel haplotypes, H5(212) and H6(122) were revealed.

The biomaterial-mediated healing of critical size bone defects in the ovariectomized rat.

UNLABELLED: This study demonstrated an impaired biomaterial-mediated bone regeneration in a critical sized calvarial defect established within an ovariectomized rat model. Histological and microtomographic evidences were supported by an impaired osteoblastic gene expression and altered expression of estrogen receptors and adipogenic markers. INTRODUCTION: This work aims to address the bone regeneration process in the ovariectomized rat model, by assessing a calvarial critical size defect implanted with a biocompatible bovine bone mineral graft. METHODS: Animals were randomly divided into two groups: Ovx (bilateral ovariectomy) and Sham (control surgery). Following 8 weeks, all animals were submitted to a surgical bicortical craniotomy (5-mm circular critical size defect), which was filled with a biocompatible mineral graft. Animals were euthanized at 1, 3, and 6 months following graft implantation (n = 10), and results on the orthotopic bone regeneration process were blindly evaluated by radiographic, microtomographic, histological, histomorphometric, and gene expression techniques. RESULTS: In the attained model, in both Sham and Ovx groups, the bone regenerative process was found to occur in a slow-paced manner. Likewise, a qualitative evaluation of the microtomographic and histological analysis, as well as quantitative data from histomorphometric indexes, revealed reduced bone regeneration in Ovx animals, at the assayed time points. Significant differences were attained at the 3 and 6 months. Gene expression analysis revealed a reduced expression of osteoblastic-related genes and an altered expression of estrogen receptors and adipogenic markers, within the regenerating bone of Ovx animals. CONCLUSIONS: Due to the similarities between the osteoporotic animal model and the human condition of postmenopausal osteoporosis, it might be relevant to consider the potential clinical implication of the osteoporotic condition in the biomaterial-mediated bone tissue healing/regeneration process.

Physical inactivity is a major contributor to ovariectomy-induced sarcopenia.

Since the mechanism(s) underlying menopause-related sarcopenia remain unknown we aimed to investigate the role of physical inactivity in its etiology. Ovariectomized and sham-operated rats were allocated into 2 experimental groups: (1) sedentary-standard housing; and (2) exercise-housed with running wheel. After a 9-month experimental period, soleus muscle structure and biochemical properties were analyzed. No differences existed in muscle fibre size or ultrastructure between sedentary sham and ovariectomized animals housed in standard conditions. In the exercise groups, average daily running distance was 10-fold less in ovariectomized compared to sham-animals. Further, in exercised animals, soleus fibre size was smaller in ovariectomized compared to sham-animals. Nonetheless, compared to both sedentary groups, muscle fibre size was larger in the exercised ovariectomized animals. Our results indicate that ovariectomy-induced sarcopenia is not due to the loss of ovarian hormones per se, but is largely due to physical inactivity.

Lifelong sedentary behaviour and femur structure.

The aim of the present study was to analyze the lifelong differences of femur structure in sedentary and physically active animal models. Thirty male C57BL/6 mice, 2 months old, were either: i) housed in cages with running wheel (AA; n=10), ii) housed in cages without running wheel (AS; n=10), iii) or sacrificed without intervention (Y; n=10). AA and AS animals were sacrificed after 23 months of housing. Right femur structure was analyzed in all animals by histomorphometry. Significant differences in several microarchitectural parameters of cancellous and cortical bone were identified between Y mice and both groups of aged mice, as well as between AA and AS groups. Lifelong physically active mice had significantly higher cancellous bone surface (Cn.BS) and trabecular number (Tb.N) and decreased trabecular separation (Tb.Sp) at both epiphyses when compared to AS animals. No differences were observed between Y and AA groups regarding osteocyte number (N.Ot) despite its significant reduction in AS animals, suggesting that age alone was not a cause for decreases in N.Ot. Our results suggest that the reduced bone quality observed in the elderly is not only a consequence of age but also of lack of physical activity since sedentary behaviour significantly aggravated the degenerative age-related bone differences.

How much does overweight impact the adolescent developmental process?

BACKGROUND: To analyse the associations between body mass index (BMI) and health-related behaviours among Portuguese adolescents based on the three waves of the Health Behaviour in School-aged Children (HBSC) survey conducted in Portugal. METHODS: Data were derived from the three waves (1998, 2002 and 2006) of the World Health Organization collaborative cross-national survey HBSC, including 17, 024 public school students (6th, 8th and 10th grades). Separate analyses of the variables under study were individually conducted for each of the three waves of the survey, and for the total sample according to BMI (normal-weight and overweight/obese) using Chi square. At a second step, a multivariate logistic regression model was tested using all the variables that were significantly associated with normal or excess BMI values at a bivariate level, in order to determine whether they would predict being overweight, when controlling for all the others in the model. RESULTS: Overweight adolescents reported their health as fair or poor more often, reported a poorer perception of academic achievement, were more likely than their peers to describe themselves as 'unhappy', and reported irritability or bad temper more often. According to our findings, being overweight can be predicted by being a male, being younger, having low body satisfaction, having a perception of poor academic achievement, of poor personal health and of being unhappy. Being overweight was not significantly predicted by the year of data collection. CONCLUSIONS: Overweight adolescents were consistently far more likely to exhibit difficulties with their physical and emotional health when compared with their non-overweight peers. Although the effects of overweight on psychosocial functioning remain incompletely defined, they may constitute important determinants of overweight persistency, as well as have a detrimental effect on the adolescent's developmental process.

Validity of BMI based on self-reported weight and height in adolescents.

AIM: To assess in a subset of a nationally representative sample of Portuguese adolescents, the validity of Body Mass Index (BMI) based on self-reported weight and height. METHODS: This study included 462 students in grades 6, 8 and 10 (mean age 14.0 +/- 1.9 years) from 12 public schools randomly selected from the list of schools which took part in the 2006 Health Behaviour in School Aged Children Portuguese survey, corresponding to approximately 10% of the sample. Self-reported weight and height were recorded and then measured. RESULTS: Prevalence of normal weight, overweight and obesity based on self-report compared with that of measured values was not significantly different for boys and girls, and among age groups. BMI based on measured weight and height was underestimated compared with BMI based on self-reported data, both among girls and boys. Larger limits of agreement were found for boys, indicating a higher variability of self-reported BMI in estimating measured BMI, specifically below the age of 14 years. CONCLUSION: These data suggest that BMI based on self-reported weight and height is not accurate for BMI prediction at an individual level. However, self-reported BMI may be used as a simple and valid tool for BMI estimates of overweight and obesity in epidemiological studies.

Shortening the postpartum anoestrous interval in suckled crossbred dual purpose cows using progestagen intravaginal sponges plus eCG and PGF(2alpha).

One hundred and twenty-six suckled crossbred cows (Bos taurus x Bos indicus), with body condition score >or=3 (1-5 point scale), were employed in the present study to evaluate the effectiveness of intravaginal progestin-releasing sponges (IVS) for shortening anoestrous interval. Fifty-four cows were assigned to control group. Seventy-two cows were treated with IVS impregnated with 250 mg of medroxy-acetate-progesterone (MAP) as follows: day 0, IVS plus 5 mg of 17beta-E and 50 mg of MAP i.m.; day 6, 500 IU of equine chorionic gonadotropin and 25 mg prostaglandin F(2alpha) i.m.; day 8, IVS withdrawal and day 9, 1 mg 17beta-E i.m. Cows were also grouped according to postpartum days (dpp) at treatment: MAP <70 days (n = 25); control <70 days (n = 22); MAP >70 days (n = 47); control >70 days (n = 32). From IVS removal, cows were detected in oestrus and inseminated. Cows not detected in oestrus were timed artificial insemination 72 h after sponge removal. Treatment effect on oestrous rate (ER), conception rate (CR), pregnancy rate (PR) and treatment to conception intervals (TCI) and calving to conception intervals (CCI) were evaluated. The ER, CR and PR were analysed using PROC LOGISTIC, while TCI and CCI with PROC GLM of SAS. The groups MAP <70 days and MAP >70 days showed higher (p < 0.01) ER than control <70 days and control >70 days (84.0% and 76.6% vs 31.8% and 31.3% respectively). The PR was higher (p < 0.01) in MAP <70 days vs control <70 days (64.0% vs 22.7%) and also higher (p < 0.05) in MAP >70 days vs control <70 days (40.4% vs 18.8%). The TCI and CCI were shorter (p < 0.01) in MAP <70 days vs control <70 days (36.0 and 95.8 days; 95.3 and 158.6 days respectively). In conclusion, only cows treated with IVS before 70 dpp had a CCI shorter than 100 days, consequently this treatment shortened postpartum anoestrous interval in crossbred dual purpose cattle.

Molecular picture of cobalamin C/D defects before and after newborn screening era.

Objective Birth prevalence of Cobalamin (Cbl) C or D defects in Portugal is an estimated 1:85,000, one of the highest worldwide. We compared the genotype/phenotype of patients identified with CblC or CblD before and after the implementation of expanded newborn screening. Methods Twenty-five Portuguese CblC/D patients, 14 symptomatic and 11 identified through screening, were diagnosed using gas chromatography or tandem mass spectrometry. Molecular characterization was performed through the study of MMACHC and MMADHC genes. Results The most common MMACHC mutation, c.271dupA, was present in 100% of MMACHC alleles of all CblC screened patients, in contrast with the 61% identified before expanded newborn screening. All studied cases (except one, who presented a CblD deficiency) presented a CblC defect. More CblC late-onset patients were diagnosed before the introduction of newborn screening than in the post newborn screening era, probably because some early onset patients died without a definitive diagnosis. Conclusion The molecular data found in this cohort contribute to the improvement of screening and diagnosis of Cbl defects and would enable a confirmatory diagnosis of these patients, reducing the need for complex, costly, laborious, and time-consuming biochemical/enzymatic tests.

Stents for bronchial stenosis after lung transplantation: should they be removed?

BACKGROUND: Airway complications after lung transplantation are the major cause of morbidity, affecting up to 33% of all cases. Bronchial stenosis is the most common complication. The use of stents has been established as the most effective therapy; however, their removal is recommended after 3-6 months of use. We have been using self-expandable stents as a definitive treatment and remove them only if necessary. For this report, we evaluated the use of self-expandable stents as a definitive treatment for bronchial stenosis after lung transplantation. METHODS: We performed a retrospective cohort study to evaluate patients with bronchial stenosis from August 2003 to April 2014. Clinical and pulmonary function test data were collected. RESULTS: Two hundred lung transplants were performed, 156 of which were bilateral. Sixteen patients experienced airway complications: 4 had dehiscence, 2 necrosis, and 10 bronchial stenosis. Of these patients, 7 had undergone bilateral procedures, and 2 patients developed stenosis in both sides. Twelve anastomotic stenoses were observed. The follow-up after stenting ranged from 1 to 7 years. All patients had increased lung function, and 4 remained stable with sustained increase in pulmonary function without episodes of infection. Three patients required removal of their prosthesis 6 months to 1 year after implantation because of complications. Two patients died owing to unrelated causes. CONCLUSIONS: Definitive treatment of bronchial stenosis with self-expandable stents is a viable option. The 1st year seems to be the most crucial for determining definitive treatment, because no patients required removal of their stent after 1 year.

Prevalence of anti-Leishmania donovani antibody among Brazilian blood donors and multiply transfused hemodialysis patients.

The prevalence of anti-Leishmania donovani antibodies was investigated in 1,500 Brazilian blood donors and multiply transfused hemodialysis patients. Sera were tested using the fucose-mannose ligand (FML) ELISA, which was shown to have 100% sensitivity and 96% specificity for kala-azar. Among 1,194 volunteer blood donors, seroreactivity was 9%, increasing to 25% in a periurban kala-azar focus. However, higher positivity (37%) was found in multiply transfused hemodialysis patients from Natal, where kala-azar is constantly present in low numbers (endemic), with sporadic outbreaks in localized regions (endemic and epidemic). Risk factors included blood transfusion, which was significantly associated with the presence of anti-Leishmania antibodies (chi2 = 8.567, P < 0.005), but did not include potential exposure to sandfly bites (chi2 = 0.033, P > 0.1). The prevalence significantly decreased to 7% in hemodialysis patients from Rio de Janeiro, where kala-azar is only occasionally seen, and was 0% in patients undergoing continuous ambulatorial peritoneal dialysis. The prospective analysis of 27 FML-seroreactive donors from Natal revealed amastigotes of Leishmania in the bone marrow of one subject while four had clinical complaints, including splenomegaly and hepatosplenomegaly. Our results point to the need for control of blood transfusion as a possible route for transmission of kala-azar in endemic areas.

Health risk behaviors and associated risk and protective factors among Brazilian adolescents in Santos, Brazil.

OBJECTIVE: To describe the prevalence of health risk behaviors and identify risk and protective factors that are associated with several health risk behaviors (cigarette smoking, drug use, onset of sexual intercourse before age 15, pregnancy, gun-carrying, suicidal ideation, and suicide attempts) among adolescents in Brazil, as well as to explore gender differences. METHODS: We estimated prevalence rates, evaluated bivariate associations, and explored multivariate analyses using logistic regression on data from a 1997 survey of adolescent health among 2059 eighth- and 10(th)-grade students in Santos, Brazil. RESULTS: Youth in Santos, Brazil report high rates of gun-carrying, suicidal thoughts and attempts, sexual intercourse, and pregnancy. Factors associated with diminished involvement for nearly all health risk behaviors, for both boys and girls, included having good family relationships, and feeling liked by friends and teachers. Factors associated with increases in nearly all health risk behaviors were: gun-carrying and gun availability in the home, drug use, and sexual abuse. CONCLUSIONS: Factors that are associated with a wide range of health risk behaviors among adolescents in Brazil appear to parallel those found in industrialized countries: access to guns, substance use, and sexual abuse. Likewise, connectedness to family, school, and peers is consistently the protective factor associated with diminished risky behaviors.

Influences of epidermal growth factor and insulin-like growth factor-I on bovine blastocyst development in vitro.

Experiments were carried out to investigate putative beneficial effects of adding epidermal growth factor (EGF) or insulin-like growth factor-I (IGF-I) for bovine embryo culture in chemically defined media. Presumptive zygotes (18 h post-insemination) were randomly assigned to culture treatments. In experiment 1, treatments involved additions of recombinant human EGF to provide concentrations of 0 ng (control), 1, 5, and 25 ng/ml. No differences were seen in numbers of 4-cell stage embryos between groups. A concentration of 5 ng/ml EGF but not 1 or 25 ng/ml during embryo culture improved percentages of 4-cell stage embryos reaching blastocysts compared to the control (P<0.05). Numbers of inner cell mass (ICM) cells and trophoblast cells of day 8 blastocysts were similar for the control and 5 ng/ml EGF-treated groups. In experiment 2, culture with recombinant human IGF-I in concentrations of 0 ng (control), 2, 10, and 50 ng/ml resulted in no differences in numbers of 4-cell stage embryos between groups. When compared to controls, IGF-I treatments at 10 and 50 ng/ml improved proportions of 4-cell stage embryos that reached blastocysts (P<0.05). In experiment 3, numbers of ICM cells of day 8 blastocysts were significantly higher after being cultured with 50 ng/ml of IGF-I compared to those of the controls (P<0.05). No additive effect of combining EGF (5 ng/ml) and IGF-I (50 ng/ml) was seen when results were compared to those following supplementation of the media with either EGF or IGF-I alone. In conclusion, both EGF and IGF-I could independently enhance bovine preimplantational development in chemically defined media and IGF-I but not EGF may play a mitogenic role during early bovine development.

Offspring resulting from direct transfer of cryopreserved bovine embryos produced in vitro in chemically defined media.

The present work was designed to study the in vitro and in vivo viability, as assessed by blastocyst formation, pregnancy rate and term delivery of bovine embryos produced under completely defined conditions with or without insulin-like growth factor I (IGF-I) following direct transfer after cryopreservation. Slaughterhouse-derived bovine oocytes were matured for 24h, fertilized with frozen-thawed spermatozoa and cultured in vitro under completely defined conditions with or without exposure to IGF-I (5 ng/ml). Only those embryos classified as excellent or good quality blastocysts were frozen. Each blastocyst was individually loaded into a straw, seeded and pre-cooled to -7 degrees C. After 10 min at -7 degrees C straws were frozen further to -30 degrees C at a rate of 0.3 degrees C/min and then plunged into liquid nitrogen. Synchronized recipient cows received one embryo in the horn ipsilateral to the corpus luteum (CL). Pregnancies were diagnosed by ultrasonography 35-45 days after embryo transfer (ET). IGF-I failed to improve cleavage rate, as well as blastocyst production, when added during in vitro culture (IVC). Pregnancy outcome was not significantly improved in cows that received an IGF-I-treated embryo compared with controls (4/10 versus 3/10, respectively). Five out of six calves delivered to date were born alive and healthy. We have shown that it is possible to obtain healthy live offspring from frozen-thawed embryos produced under chemically defined conditions after direct transfer.

Embryotoxic effects adjacent and opposite to the early regressing bovine corpus luteum.

Early luteal regression in cattle has an embryotoxic effect that is not overcome by replacement with progesterone, but is prevented by removal of the regressing CL. Two experiments were designed to test the null hypothesis that the luteal component of the embryotoxic effect is delivered by a systemic pathway. Beef heifers and cows (n = 39) received two good quality embryos, one placed into each uterine horn on Day 6 or 7 of the estrous cycle. Treated animals (n = 20) received 15 mg of PGF2alpha three times per day from Day 7 (n = 11; Experiment 1) or 5 (n = 9; Experiment 2) through 8; controls (n = 19) received saline. Progestogen replacement therapy (12 mg flurogestone acetate daily, s.c.) was provided from Day 6 (Experiment 1) or 4 (Experiment 2) until ultrasonographic diagnosis of embryo survival on Day 35 after estrus. The effects of treatment, location of the embryo and location by treatment interaction on embryo survival were tested by Chi square. In Experiment 1, there was no significant difference in embryo survival rate between PGF2alpha-treated and control recipients. In Experiment 2, only 6 of 18 embryos survived to Day 35 when transferred to animals treated with PGF2alpha compared to 12 of 18 in control animals (P< 0.05). The survival of embryos did not differ with location (adjacent or opposite to the regressing CL) or location by treatment interaction. Thus no evidence was obtained to support a local effect of the regressing CL. The embryo mortality associated with luteolytic doses of PGF2alpha in cows receiving replacement therapy with progestogen probably involves compounds that either act systemically or are transported via the uterine lumen to the uterine horn contralateral to the regressing CL.

Effect of leukemia inhibitory factor on bovine embryos produced in vitro under chemically defined conditions.

The objective of these experiments was to assess putative embryotrophic effects of leukemia inhibitory factor (LIF) on bovine preimplantation development in chemically defined media. Recombinant human LIF was added to embryo culture media at a concentration of 100 ng/ml. When added for culture of morulae LIF had no positive effect on the proportion of embryos reaching the blastocyst stage. However, LIF significantly reduced development to the blastocyst stage when added for culture of 4-cell stage embryos (P<0.05). In contrast, a positive effect was found for progression of blastocyst development. In vitro blastocyst hatching rates were significantly improved in the presence of LIF (P<0.02). Number of total cells and of inner cell mass (ICM) cells were increased in LIF-treated blastocysts. In vitro survival of frozen-thawed blastocysts was not improved by adding LIF to morula stage embryos before cryopreservation. The pregnancy rate after direct transfer of cryopreserved LIF-treated embryos was not different from that for untreated control embryos. Data indicate that addition of LIF has no major beneficial effect on bovine embryos produced in these chemically defined conditions.