GDF15 linked to maternal risk of nausea and vomiting during pregnancy.

GDF15, a hormone acting on the brainstem, has been implicated in the nausea and vomiting of pregnancy, including its most severe form, hyperemesis gravidarum (HG), but a full mechanistic understanding is lacking1-4. Here we report that fetal production of GDF15 and maternal sensitivity to it both contribute substantially to the risk of HG. We confirmed that higher GDF15 levels in maternal blood are associated with vomiting in pregnancy and HG. Using mass spectrometry to detect a naturally labelled GDF15 variant, we demonstrate that the vast majority of GDF15 in the maternal plasma is derived from the feto-placental unit. By studying carriers of rare and common genetic variants, we found that low levels of GDF15 in the non-pregnant state increase the risk of developing HG. Conversely, women with ß-thalassaemia, a condition in which GDF15 levels are chronically high5, report very low levels of nausea and vomiting of pregnancy. In mice, the acute food intake response to a bolus of GDF15 is influenced bi-directionally by prior levels of circulating GDF15 in a manner suggesting that this system is susceptible to desensitization. Our findings support a putative causal role for fetally derived GDF15 in the nausea and vomiting of human pregnancy, with maternal sensitivity, at least partly determined by prepregnancy exposure to the hormone, being a major influence on its severity. They also suggest mechanism-based approaches to the treatment and prevention of HG.

Fetally-encoded GDF15 and maternal GDF15 sensitivity are major determinants of nausea and vomiting in human pregnancy.

Human pregnancy is frequently accompanied by nausea and vomiting that may become severe and life-threatening, as in hyperemesis gravidarum (HG), the cause of which is unknown. Growth Differentiation Factor-15 (GDF15), a hormone known to act on the hindbrain to cause emesis, is highly expressed in the placenta and its levels in maternal blood rise rapidly in pregnancy. Variants in the maternal GDF15 gene are associated with HG. Here we report that fetal production of GDF15, and maternal sensitivity to it, both contribute substantially to the risk of HG. We found that the great majority of GDF15 in maternal circulation is derived from the feto-placental unit and that higher GDF15 levels in maternal blood are associated with vomiting and are further elevated in patients with HG. Conversely, we found that lower levels of GDF15 in the non-pregnant state predispose women to HG. A rare C211G variant in GDF15 which strongly predisposes mothers to HG, particularly when the fetus is wild-type, was found to markedly impair cellular secretion of GDF15 and associate with low circulating levels of GDF15 in the non-pregnant state. Consistent with this, two common GDF15 haplotypes which predispose to HG were associated with lower circulating levels outside pregnancy. The administration of a long-acting form of GDF15 to wild-type mice markedly reduced subsequent responses to an acute dose, establishing that desensitisation is a feature of this system. GDF15 levels are known to be highly and chronically elevated in patients with beta thalassemia. In women with this disorder, reports of symptoms of nausea or vomiting in pregnancy were strikingly diminished. Our findings support a causal role for fetal derived GDF15 in the nausea and vomiting of human pregnancy, with maternal sensitivity, at least partly determined by pre-pregnancy exposure to GDF15, being a major influence on its severity. They also suggest mechanism-based approaches to the treatment and prevention of HG.

Approaches to screening for hyperglycaemia in pregnant women during and after the COVID-19 pandemic.

AIM: To evaluate the diagnostic and prognostic performance of alternative diagnostic strategies to oral glucose tolerance tests, including random plasma glucose, fasting plasma glucose and HbA1c , during the COVID-19 pandemic. METHODS: Retrospective service data (Cambridge, UK; 17 736 consecutive singleton pregnancies, 2004-2008; 826 consecutive gestational diabetes pregnancies, 2014-2019) and 361 women with ≥1 gestational diabetes risk factor (OPHELIA prospective observational study, UK) were included. Pregnancy outcomes included gestational diabetes (National Institute of Health and Clinical Excellence or International Association of Diabetes and Pregnancy Study Groups criteria), diabetes in pregnancy (WHO criteria), Caesarean section, large-for-gestational age infant, neonatal hypoglycaemia and neonatal intensive care unit admission. Receiver-operating characteristic curves and unadjusted logistic regression were used to compare random plasma glucose, fasting plasma glucose and HbA1c performance. RESULTS: Gestational diabetes diagnosis was significantly associated with random plasma glucose at 12 weeks [area under the receiver-operating characteristic curve for both criteria 0.81 (95% CI 0.79-0.83)], fasting plasma glucose [National Institute of Health and Clinical Excellence: area under the receiver-operating characteristic curve 0.75 (95% CI 0.65-0.85); International Association of Diabetes and Pregnancy Study Groups: area under the receiver-operating characteristic curve 0.92 (95% CI 0.85-0.98)] and HbA1c at 28 weeks' gestation [National Institute of Health and Clinical Excellence: 0.83 (95% CI 0.75-0.90); International Association of Diabetes and Pregnancy Study Groups: 0.84 (95% CI 0.77-0.91)]. Each measure predicts some, but not all, pregnancy outcomes studied. At 12 weeks, ~5% of women would be identified using random plasma glucose ≥8.5 mmol/l (sensitivity 42%; specificity 96%) and at 28 weeks using HbA1c ≥39 mmol/mol (sensitivity 26%; specificity 96%) or fasting plasma glucose ≥5.2-5.4 mmol/l (sensitivity 18-41%; specificity 97-98%). CONCLUSIONS: Random plasma glucose at 12 weeks, and fasting plasma glucose or HbA1c at 28 weeks identify women with hyperglycaemia at risk of suboptimal pregnancy outcomes. These opportunistic laboratory tests perform adequately for risk stratification when oral glucose tolerance testing is not available.

Barriers to completing oral glucose tolerance testing in women at risk of gestational diabetes.

AIM: Complications of gestational diabetes (GDM) can be mitigated if the diagnosis is recognized. However, some at-risk women do not complete antenatal diagnostic oral glucose tolerance testing (OGTT). We aimed to understand reasons contributing to non-completion, particularly to identify modifiable factors. METHODS: Some 1906 women attending a tertiary UK obstetrics centre (2018-2019) were invited for OGTT based on risk-factor assessment. Demographic information, test results and reasons for non-completion were collected from the medical record. Logistic regression was used to analyse factors associated with non-completion. RESULTS: Some 242 women (12.3%) did not complete at least one OGTT, of whom 32.2% (n = 78) never completed testing. In adjusted analysis, any non-completion was associated with younger maternal age [≤ 30 years; odds ratio (OR) 2.3, 95% confidence interval (CI) 1.6-3.4; P < 0.001], Black African ethnicity (OR 2.7, 95% CI 1.2-5.5; P = 0.011), lower socio-economic status (OR 0.9, 95% CI 0.8-1.0; P = 0.021) and higher parity (≥ 2; OR 1.8, 95% CI 1.1-2.8; P = 0.013). Non-completion was more likely if testing indications included BMI ≥ 30 kg/m2 (OR 1.7, 95% CI 1.1-2.4; P = 0.009) or family history of diabetes (OR 2.2, 95% CI 1.5-3.3; P < 0.001) and less likely if the indication was an ultrasound finding (OR 0.4, 95% CI 0.2-0.9; P = 0.035). We identified a common overlapping cluster of reasons for non-completion, including inability to tolerate test protocol (21%), social/mental health issues (22%), and difficulty keeping track of multiple antenatal appointments (15%). CONCLUSIONS: There is a need to investigate methods of testing that are easier for high-risk groups to schedule and tolerate, with fuller explanation of test indications and additional support for vulnerable groups.

Seasonal variations in incidence and maternal-fetal outcomes of gestational diabetes.

AIMS: To determine whether the neonatal and delivery outcomes of gestational diabetes vary seasonally in the context of a relatively cool temperate climate. METHODS: A retrospect cohort of 23 735 women consecutively delivering singleton, live-born term infants in a single tertiary obstetrics centre in the UK (2004-2008) was identified. A total of 985 (4.1%) met the diagnostic criteria for gestational diabetes. Additive dynamic regression models, adjusted for maternal age, BMI, parity and ethnicity, were used to compare gestational diabetes incidence and outcomes over annual cycles. Outcomes included: random plasma glucose at booking; gestational diabetes diagnosis; birth weight centile; and delivery mode. RESULTS: The incidence of gestational diabetes varied by 30% from peak incidence (October births) to lowest incidence (March births; P=0.031). Ambient temperature at time of testing (28 weeks) was strongly positively associated with diagnosis (P<0.001). Significant seasonal variation was evident in birth weight in gestational diabetes-affected pregnancies (average 54th centile June to September; average 60th centile December to March; P=0.027). Emergency Caesarean rates also showed significant seasonal variation of up to 50% (P=0.038), which was closely temporally correlated with increased birth weights. CONCLUSIONS: There is substantial seasonal variation in gestational diabetes incidence and maternal-fetal outcomes, even in a relatively cool temperate climate. The highest average birth weight and greatest risk of emergency Caesarean delivery occurs in women delivering during the spring months. Recognizing seasonal variation in neonatal and delivery outcomes provides new opportunity for individualizing approaches to managing gestational diabetes.

A qualitative study of the acceptability of cognitive bias modification for paranoia (CBM-pa) in patients with psychosis.

BACKGROUND: Cognitive Bias Modification (CBM) has been used successfully as a computer-based intervention in disorders such as anxiety. However, CBM to modify interpretations of ambiguous information relevant to paranoia has not yet been tested. We conducted a qualitative investigation of a novel intervention called CBM for paranoia (CBM-pa) to examine its acceptability in patients with psychosis. METHODS: Eight participants with psychosis who completed CBM-pa were identified by purposive sampling and invited for a semi-structured interview to explore the facilitators and barriers to participation, optimum form of delivery, perceived usefulness of CBM-pa and their opinions on applying CBM-pa as a computerised intervention. The interviews were transcribed and analysed using thematic analysis by researchers working in collaboration with service users. RESULTS: Themes emerged relating to participants' perception about delivery, engagement, programme understanding, factors influencing experience, perceived impact and application of CBM-pa. CBM-pa was regarded as easy, straightforward and enjoyable. It was well-accepted among those we interviewed, who understood the procedure as a psychological intervention. Patients reported that it increased their capacity for adopting alternative interpretations of emotionally ambiguous scenarios. Although participants all agreed on the test-like nature of the current CBM-pa format, they considered that taking part in sessions had improved their overall wellbeing. Most of them valued the computer-based interface of CBM-pa but favoured the idea of combining CBM-pa with some form of human interaction. CONCLUSIONS: CBM-pa is an acceptable intervention that was well-received by our sample of patients with paranoia. The current findings reflect positively on the acceptability and experience of CBM-pa in the target population. Patient opinion supports further development and testing of CBM-pa as a possible adjunct treatment for paranoia. TRIAL REGISTRATION: Current Controlled Trials ISRCTN: 90749868 . Retrospectively registered on 12 May 2016.

Improving outcomes in gestational diabetes: does gestational weight gain matter?

AIM: Excessive gestational weight gain increases risk of gestational diabetes mellitus (GDM) but it remains unclear whether weight control after GDM diagnosis improves outcomes. We assessed whether: (1) total gestational weight gain during pregnancy (0-36 weeks); (2) early gestational weight gain (0-28 weeks, before GDM diagnosis); or (3) late gestational weight gain (28-36 weeks, after diagnosis) are associated with maternal-fetal outcomes. METHODS: Some 546 women with GDM who delivered viable singleton infants at a single UK obstetric centre (October 2014 to March 2017) were included in this retrospective observational study. RESULTS: Higher total gestational weight gain was associated with Caesarean section [n = 376; odds ratio (OR) 1.05; confidence intervals (CI) 1.02-1.08, P < 0.001] and large for gestational age (OR 1.08; CI 1.03-1.12, P < 0.001). Higher late gestational weight gain (28-36 weeks; n = 144) was associated with large for gestational age (OR 1.17; CI 1.01-1.37, P < 0.05), instrumental deliveries (OR 1.26; CI 1.03-1.55, P < 0.01), higher total daily insulin doses (36 weeks; beta coefficient 4.37; CI 1.92-6.82, P < 0.001), and higher post-partum 2-h oral glucose tolerance test concentrations (beta coefficient 0.12; CI 0.01-0.22, P < 0.05). Women who avoided substantial weight gain after GDM diagnosis had 0.7 mmol/l lower postnatal 2-h glucose and needed half the amount of insulin/day at 36 weeks compared with women with substantial weight gain after diagnosis. There were no significant associations between early gestational weight gain (0-28 weeks) and pregnancy outcomes. CONCLUSIONS: These findings suggest that controlling gestational weight gain should be a priority following GDM diagnosis to optimize pregnancy outcomes and improve maternal postnatal glucose homeostasis. The period after diagnosis of GDM (often 28 weeks gestation) is not too late to offer lifestyle advice or intervention to improve weight management and pregnancy outcomes.

Supervised Machine-Learning Reveals That Old and Obese People Achieve Low Dapsone Concentrations.

The human species is becoming increasingly obese. Dapsone, which is extensively used across the globe for dermatological disorders, arachnid bites, and for treatment of several bacterial, fungal, and parasitic diseases, could be affected by obesity. We performed a clinical experiment, using optimal design, in volunteers weighing 44-150 kg, to identify the effect of obesity on dapsone pharmacokinetic parameters based on maximum-likelihood solution via the expectation-maximization algorithm. Artificial intelligence-based multivariate adaptive regression splines were used for covariate selection, and identified weight and/or age as predictors of absorption, systemic clearance, and volume of distribution. These relationships occurred only between certain patient weight and age ranges, delimited by multiple hinges and regions of discontinuity, not identified by standard pharmacometric approaches. Older and obese people have lower drug concentrations after standard dosing, but with complex patterns. Given that efficacy is concentration-dependent, optimal dapsone doses need to be personalized for obese patients.

A systematic review and meta-analysis of the post-operative adverse effects associated with mosquito net mesh in comparison to commercial hernia mesh for inguinal hernia repair in low income countries.

PURPOSE: Abdominal wall hernia is a common surgical condition, with more than 20 million estimated to be repaired each year. Mesh repair is the standard for most repairs; however, the mesh material itself may be a barrier to care, the cost prohibitively high for some populations and healthcare systems. The aim of this systematic review and meta-analysis was to produce a pooled comparison between the adverse event rate associated with mosquito net mesh and commercial hernia mesh. METHODS: A systematic review was carried out in accordance with PRISMA guidelines. PubMed, Ovid Embase/Medline, SCOPUS, Web of Science and the Cochrane library were searched. In addition, the ISRCTN register, ClinicalTrials.gov, ICTR Platform and EU Clinical Trials Register were searched. RESULTS: Five randomised controlled trials (RCTs) were identified. The RCTs were deemed to have similar sample populations after inspection of their sample parameters. Therefore, the adverse effects were compared individually (reoccurrence, haematoma, seroma, infection, and serous discharge) and pooled. A total of 313 mosquito net meshes were included in the study, there was no significant difference between the intervention and control groups for pooled adverse effects or individually. CONCLUSIONS: There is not a significant difference between the commercial mesh group and the mosquito net mesh group for pooled [odds ratio 0.93 (0.63, 1.35)] and individual adverse event rates. However, the 95% confidence intervals of these results are still wide. To reduce this uncertainty sample sizes must increase in future studies.

Fractal Geometry-Based Decrease in Trimethoprim-Sulfamethoxazole Concentrations in Overweight and Obese People.

Trimethoprim-sulfamethoxazole (TMP-SMX) is one of the most widely drugs on earth. The World Health Organization recommends it as an essential basic drug for all healthcare systems. Dosing is inconsistently based on weight, assuming linear relationships. Given that obesity is now a global "pandemic" it is vital that we evaluate the effect of obesity on trimethoprim-sulfamethoxazole concentrations. We conducted a prospective clinical experiment based on optimized design strategies and artificial intelligence algorithms and found that weight and body mass index (BMI) had a profound effect on drug clearance and volume of distribution, and followed nonlinear fractal geometry-based relationships. The findings were confirmed by demonstrating decreased TMP-SMX peak and area under the concentration-time curves in overweight patients based on standard regression statistics. The nonlinear relationships can now be used to identify new TMP-SMX doses in overweight and obese patients for each of the infections caused by the >60 pathogens for which the drug is indicated.

Trichomonas vaginalis induces cytopathic effect on human lung alveolar basal carcinoma epithelial cell line A549.

Trichomonas vaginalis, the causative agent of trichomoniasis is generally known to inhabit the genitourinary tract. However, several case reports with supporting molecular and immunological identifications have documented its occurrence in the respiratory tract of neonates and adults. In addition, the reports have documented that its occurrence is associated with respiratory failures. The medical significance or consequence of this association is unclear. Thus, to establish the possible outcome from the interaction of T. vaginalis with lung cells, the cytopathic effects of the parasites were evaluated using monolayer cultures of the human lung alveolar basal carcinoma epithelial cell line A549. The possible effect of association of T. vaginalis with A549 epithelial cells was analyzed using phase-contrast, scanning electron microscopy and fluorescence microscopy. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), crystal-violet and TUNEL (terminal deoxynucleotidyltransferase-mediated dUTP nick-end labelling) assays were conducted for cytotoxicity testing. The results demonstrate that T. vaginalis: (1) adheres to A549 epithelial cells, suggesting a density-dependent parasite-cell association; (2) adherence on A549 is through flagella, membrane and axostyle; (3) causes cell detachment and cytotoxicity (50-72.4%) to A549 and this effect is a function of parasite density; and (4) induces apoptosis in A549 about 20% after 6 h of incubation. These observations indicate that T. vaginalis causes cytopathic effects on A549 cell. To date, this is the first report showing a possible interaction of T. vaginalis with the lung cells using A549 monolayer cultures. Further studies are recommended to completely elucidate this association.

Evidence of biochemical hyperandrogenism in women: the limitations of serum testosterone quantitation.

Hyperandrogenism in women is a common clinical scenario and is characterised by menstrual disturbance, hirsutism and infertility. Accurate measurement of serum testosterone is often used in these patients to diagnose polycystic ovary syndrome (PCOS) and to prompt further investigation in patients with suspected androgen-secreting tumours. Immunoassay methods are commonly used for serum testosterone quantitation, although the 'gold standard' reference method is mass spectrometry (MS), which is only available at certain tertiary centres. In this retrospective observational study, 57 female patients were investigated for possible hyperandrogenism. Biochemical testing for testosterone using an immunoassay was compared to an MS method. Correlation between the immunoassay and MS method was worse at lower testosterone concentrations, however overall, gave a reasonably strong correlation coefficient of 0.73. This study highlights the ongoing controversy over the most reliable test for hyperandrogenism in clinical practice. It is vital that clinicians are aware of the limitations of these methods and the clinical repercussions.

Efficacy of increasing dosages of clarithromycin for treatment of experimental Mycoplasma pneumoniae pneumonia.

OBJECTIVES: Mycoplasma pneumoniae respiratory infection is a common cause of acute respiratory infection in children and adults. We evaluated the efficacy of increasing dosages of clarithromycin for the optimized therapy of M. pneumoniae respiratory infection in a mouse model. METHODS: BALB/c mice were intranasally inoculated once with M. pneumoniae or SP4 broth (control). Groups of mice were treated with increasing dosages of clarithromycin (10, 25 or 75 mg/kg/day) or placebo subcutaneously daily. Groups of mice were evaluated after 1, 2, 3, 6 and 12 days of therapy. Outcome variables included quantitative M. pneumoniae culture, histopathological score of the lungs, bronchoalveolar lavage (BAL) cytokine/chemokine/growth factor concentrations and plethysmography after aerosolized methacholine to assess airway hyperresponsiveness. RESULTS: Elevated dosages of clarithromycin resulted in greater antimicrobial efficacy with significantly reduced M. pneumoniae quantitative cultures (P < 0.05), as well as greater improvement in markers of disease severity with significantly reduced lung histopathology scores, BAL cytokine concentrations and airway hyperresponsiveness (P < 0.05). CONCLUSIONS: Escalated dosing of clarithromycin resulted in significantly greater therapeutic efficacy in the treatment of experimental M. pneumoniae respiratory infection.

Use of high-intensity statin therapy with simvastatin 80 mg and atorvastatin 80 mg in primary care.

AIMS: Cardiovascular disease (CVD) is the most common cause of death worldwide. Pharmaceutical risk reduction with high-intensity statin therapy is advisable for high-risk patients. Clinicians face a conflict between prescribing for cost (simvastatin 80 mg) or for efficacy (atorvastatin 80 mg). The aim of this audit was to examine the use, efficacy and tolerability of high intensity statin treatment (simvastatin 80 mg; atorvastatin 80 mg) in primary care. METHODOLOGY: Electronic medical records were examined from two general practitioners' surgeries. Analyses involved Mann-Whitney U and χ(2) tests. RESULTS: A total of 116 patients had taken simvastatin 80 mg or atorvastatin 80 mg. Patients were similar between treatment groups: mostly men (62.9%), over 60 years old (68.1%), non-smokers (81.0%) taking statins for secondary prevention (56.9%). More patients on simvastatin withdrew from treatment as a result of inefficacy (49.3% vs. 23.2%, p=0.025) compared with the atorvastatin group. Furthermore, patients on simvastatin were more likely to be failing conventional targets of lipid control, compared with patients on atorvastatin 80 mg (43.5% vs. 21.3%, p=0.006). Tolerability was similar between the two groups. DISCUSSION: UK guidelines recommend simvastatin 80 mg as an economic choice, despite scant evidence at this dose and recent safety concerns. Conversely, robust evidence exists for atorvastatin 80 mg. Head-to-head clinical trials or clinical studies comparing these agents are lacking. The present study suggests that atorvastatin 80 mg compares favourably to simvastatin in terms of efficacy and has a similar tolerability profile. CONCLUSION: This retrospective observational study suggests that despite national guidelines, atorvastatin 80 mg is used in clinical practice and is more effective and at least as well tolerated as simvastatin 80 mg.

A systematic review of exercise trials post stroke.

OBJECTIVE: To perform a systematic review of exercise trials post stroke. DESIGN: A systematic review of controlled clinical trials. SEARCH STRATEGY: MEDLINE, EMBASE, CINAHL, Amed, Sports Discus, Cochrane controlled trials register and PEDro were searched for relevant trials. INCLUSION CRITERIA: Studies--randomized or quasi-randomized controlled clinical trials. Participants--Adults of any age with a clinical diagnosis of stroke. Interventions--Any cardiovascular exercise intervention aimed at improving cardiovascular fitness and/or function. OUTCOMES: Impairment: gait speed, strength, endurance, balance, flexibility, tonus and exercise capacity. Disability: global dependency, functional independence. Extended activities of daily living. Quality of life. Death. DATA COLLECTION AND ANALYSIS: Two independent reviewers categorized selected trials, documented the methodological quality and extracted the relevant data. Comparisons of cardiovascular exercise interventions versus no cardiovascular intervention were made. Statistical comparisons were carried out using a random effects model to calculate standardized mean differences. RESULTS: We identified three eligible trials. Small numbers and heterogeneous outcomes limited the analyses and comparisons. Based on the limited data available, we found that cardiovascular exercise post stroke was no better than no exercise with respect to disability, impairment, extended activities of daily living, quality of life and death. CONCLUSION: Insufficient evidence was identified to establish if cardiovascular exercise has a positive effect on disability, impairment, extended activities of daily living, quality of life and case fatality post stroke.

The presence of inducible cytochrome P450 types 1A1 and 1A2 in the BeWo cell line.

The activity and inducibility of cytochrome P450 systems (CYP1A1:1A2) of the human placenta were assessed in a representative human trophoblast-like cell line, BeWo. The activity of CYP1A1 and CYP1A2 in microsome preparations from human liver, placenta, primary cultures of human cytotrophoblast, and BeWo cells was measured by O -dealkylation of 7-ethoxyresorufin (EROD) and 7-methoxyresorufin O -demethylation (MROD), respectively. Results indicated high EROD and MROD activity associated with human liver microsomes, sometimes comparable activities in human placenta microsomes prepared from smokers, and relatively low activities in human placenta microsomes from nonsmokers and in the primary cultures of cytotrophoblasts isolated from nonsmokers. Microsomes from BeWo cell monolayers exhibited the lowest EROD and MROD activities relative to all other microsome preparations. However, compared to primary cultures of normal trophoblasts, the EROD activity of the BeWo cells was far more sensitive to typical inducers, 3-methylcholanthrene, 1,2-benzanthracene, and beta-naphthoflavone. EROD activity in BeWo cells was induced approximately 200-fold by 3-methylcholanthrene. Both EROD and MROD activity in BeWo cells was readily induced by 1,2-benzanthracene, 100-fold and 60-fold, respectively. After induction with 1,2-benzanthracene, the CYP1A1 selective inhibitor, alpha-naphthoflavone, and the CYP1A2 selective inhibitor, furafylline, effectively inhibited enzyme activities with IC(50)s of 2.4 microM and 12.8 microM, respectively, in microsomes from both trophoblasts culture systems. These results show that major cytochrome P450 forms present in human placenta are present and inducible in BeWo cells, a potential model for investigation of drug metabolism mechanisms in the human trophoblast.

Assessing the efficacy of a ram-genotyping programme to reduce susceptibility to scrapie in Great Britain.

Susceptibility to clinical scrapie is associated with polymorphisms in the PrP gene. The 'ARR' allele of this gene reduces susceptibility to clinical disease caused by all known strains of the transmissible spongiform encephalopathy (TSE) agent. The British government proposes to use a ram-genotyping scheme to breed genetic resistance to clinical scrapie into the national sheep population. We considered how best to target limited genotyping resources to achieve the maximum rate of genotype evolution. We created a metapopulation model of the British sheep industry, which includes the major pure-breeds of sheep and the cross-breeds produced by crossing these pure-bred animals. The main criterion for assessing the efficacy of different strategies was the time taken to increase the prevalence of the ARR allele in the slaughter-lamb population. Our model predicted that the most-effective strategy would be to target genotyping to those rams used for pure-breeding (i.e. mated with the same breed of ewe). This strategy was compared to two further strategies, in which the proportion of rams genotyped in each breed depended on the prevalence of the ARR/ARR genotype in that breed. A policy in which the proportion of animals genotyped is reduced as the ARR prevalence in that breed increases is efficient. The most-effective policy was targeting the hill sector in the early years and gradually switching to genotyping more terminal-sire and longwool rams as the resistance of the hill sector increases.

Spatial confinement of avidin domains in microwell arrays.

Microwell arrays were chemically etched across the distal faces of coherent fiber-optic bundles. A typical 1.6 mm diameter array comprised approximately 3000 individual microwells that were approximately 1-14 microm deep and approximately 22 microm wide. A methodology involving organosilane functionalized microwell surfaces and site-selective photobiotin chemistry was developed to partially fill microwells with a thin avidin layer. Avidin microwell arrays were characterized using charge coupled device optical microscopy and scanning electron microscopy. The avidin microwell arrays had individual well volumes that were six orders of magnitude smaller and up to 30-fold more numerous than commercially available avidin-coated microtiter plates. Preliminary results indicated that individual avidin microwells were ideally suited to house single biological cells. Using standard epifluorescence microscope optics and a mercury-arc lamp, an individual 22 microm wide microwell could be optically addressed and selectively filled with avidin without the use of a photolithographic mask. The ability to control both the size and position of avidin domains on the microwell array surface demonstrates the utility of this methodology towards fabricating a single microwell array with multianalyte sensing capabilities.

Efficacy of VectoLex WDG against Anopheles quadrimaculatus and Psorophora columbiae larvae in Arkansas and Mississippi rice.

In 1999, an aerial application of VectoLex WDG (water-dispersible granules) at 1.68 and 0.56 kg/ha, applied against sentinel 3rd-stage larvae of Psorophora columbiae installed in 0.42-ha rice plots 48 h after treatment, provided no control at 72 and 96 h after treatment. Less than 10% reduction was obtained at both rates 8 and 9 days after treatment against larvae of Ps. columbiae installed at 7 days after treatment. In a later test, VectoLex WDG manually applied at 5.04 and 1.68 kg/ha to small rice plots containing sentinel 3rd-stage larvae of Ps. columbiae and Anopheles quadrimaculatus obtained 90 and 97% control of Ps. columbiae at both rates, respectively, 24 h after treatment. A 2nd installation of Ps. columbiae at 24 h after treatment resulted in 7% and no control at both rates, respectively, even in the presence of larval carcasses from the 1st installation. VectoLex WDG was not effective against Ps. columbiae after 24 h atter treatment at either rate. Poor control was obtained at both rates against An. quadrimaculatus 24 h and 48 h after treatment for both installations. Two types of commercial rice fields containing native populations of larvae of An. quadrimaculatus were used for field tests in Cleveland, MS. In 1999, VectoLex WDG, aerially applied at 1.68 and 0.56 kg/ha to 0.2-ha plots in a contoured rice field, produced 81 and 85% reductions in early (neonate and 1st- and 2nd-stage) larvae and 94 and 76% reductions in late (3rd- and 4th-stage) larvae 2 days after treatment, respectively. At 2 days after treatment, means for all 4 developmental groupings (early larvae, late larvae, pupae, and combined stages) were significantly higher in untreated plots. Both VectoLex WDG rates did not differ significantly from one another. At 8 days after treatment, untreated plots contained significantly greater mean numbers of early larvae, late larvae, and combined stages, whereas both VectoLex WDG treatments were not significantly different. In 2000, VectoLex WDG applied at 1.68 kg/ha to two 0.40-ha plots in a precision-leveled field yielded 59 and 100% reductions of early and late larvae, respectively, 2 days after treatment. Reduction of late larvae remained 100% at 8 days after treatment. The numbers of late larvae, pupae, and combined stages were significantly greater in the untreated plot 2 days after treatment. At 8 days after treatment, numbers of early larvae and combined stages were significantly higher in the VectoLex WDG plot, whereas numbers of late larvae were significantly higher in the untreated plot. The differences in susceptibility of Ps. columbiae and An. quadrimaculatus to VectoLex WDG could be attributed to species differences in larval feeding behavior, body positioning in the water column, and developmental time. In tests in Arkansas, Ps. columbiae were controlled more quickly, usually within 24 h of exposure, whereas the percent reduction for An. quadrimaculatus in both tests in Cleveland, MS, suggests that control of this species within the region tested required from 48 h up to 8 days of exposure.

Efficacy of Dibrom, Trumpet, and Scourge against four mosquito species in Louisiana.

Adult mortality of Anopheles quadrimaculatus, Culex quinquefasciatus, and the Aedes spp. complex (Aedes sollicitans and Aedes taeniorhynchus) was observed after aerial ultra-low volume (ULV) exposure to Dibrom, Trumpet, and Scourge. Dibrom was applied at 112 g active ingredient (AI)/ha, Trumpet at 112 g AI/ha, and Scourge at 1.96 g AI/ha. At all time intervals, Dibrom and Trumpet were significantly more effective against the Aedes spp. complex than against An. quadrimaculatus and Cx. quinquefasciatus. Scourge was significantly more effective against An. quadrimaculatus and Cx. quinquefasciatus than Dibrom or Trumpet. Trumpet was evaluated at lower labeled rates (28, 56, and 84 g AI/ha) against Cx. quinquefasciatus and the Aedes spp. complex. Adult mortality with Trumpet increased significantly at 1 and 24 h against Cx. quinquefasciatus. With the Aedes spp. complex, mortality increased with rate at 1 h, but at 12 and 24 h, the medium and high dosages were not significantly different from each other. Culex quinquefasciatus and the Aedes spp. complex were also subjected to ULV ground applications of Dibrom, Trumpet, and Scourge. Dibrom was applied at 22.4 g AI/ha, Trumpet at 22.4 g AI/ha, and Scourge as a 1:6 mineral oil mixture at 1.96 g AI/ha. Relative to Dibrom and Trumpet, mortality from Scourge differed greatly with mosquito species. Against Cx. quinquefasciatus, Scourge was significantly more effective than Dibrom and Trumpet at all times and distances, but against the Aedes spp. complex Scourge was significantly less effective.