Pregnancy loss in major fetal congenital heart disease: incidence, risk factors and timing.

OBJECTIVE: Fetuses with congenital heart disease (CHD) are at increased risk of pregnancy loss compared with the general population. We aimed to assess the incidence, timing and risk factors of pregnancy loss in cases with major fetal CHD, overall and according to cardiac diagnosis. METHODS: This was a retrospective, population-level cohort study of fetuses and infants diagnosed with major CHD between 1997 and 2018 identified by the Utah Birth Defect Network (UBDN), excluding cases with termination of pregnancy and minor cardiovascular diagnoses (e.g. isolated aortic/pulmonary pathology and isolated septal defects). The incidence and timing of pregnancy loss were recorded, overall and according to CHD diagnosis, with further stratification based on presence of isolated CHD vs additional fetal diagnosis (genetic diagnosis and/or extracardiac malformation). Adjusted risk of pregnancy loss was calculated and risk factors were assessed using multivariable models for the overall cohort and prenatal diagnosis subgroup. RESULTS: Of 9351 UBDN cases with a cardiovascular code, 3251 cases with major CHD were identified, resulting in a study cohort of 3120 following exclusion of cases with pregnancy termination (n = 131). There were 2956 (94.7%) live births and 164 (5.3%) cases of pregnancy loss, which occurred at a median gestational age of 27.3 weeks. Of study cases, 1848 (59.2%) had isolated CHD and 1272 (40.8%) had an additional fetal diagnosis, including 736 (57.9%) with a genetic diagnosis and 536 (42.1%) with an extracardiac malformation. The observed incidence of pregnancy loss was highest in the presence of mitral stenosis (< 13.5%), hypoplastic left heart syndrome (HLHS) (10.7%), double-outlet right ventricle with normally related great vessels or not otherwise specified (10.5%) and Ebstein's anomaly (9.9%). The adjusted risk of pregnancy loss was 5.3% (95% CI, 3.7-7.6%) in the overall CHD population and 1.4% (95% CI, 0.9-2.3%) in cases with isolated CHD (adjusted risk ratio, 9.0 (95% CI, 6.0-13.0) and 2.0 (95% CI, 1.0-6.0), respectively, based on the general population risk of 0.6%). On multivariable analysis, variables associated with pregnancy loss in the overall CHD population included female fetal sex (adjusted odds ratio (aOR), 1.6 (95% CI, 1.1-2.3)), Hispanic ethnicity (aOR, 1.6 (95% CI, 1.0-2.5)), hydrops (aOR, 6.7 (95% CI, 4.3-10.5)) and additional fetal diagnosis (aOR, 6.3 (95% CI, 4.1-10)). On multivariable analysis of the prenatal diagnosis subgroup, years of maternal education (aOR, 1.2 (95% CI, 1.0-1.4)), presence of an additional fetal diagnosis (aOR, 2.7 (95% CI, 1.4-5.6)), atrioventricular valve regurgitation ≥ moderate (aOR, 3.6 (95% CI, 1.3-8.8)) and ventricular dysfunction (aOR, 3.8 (95% CI, 1.2-11.1)) were associated with pregnancy loss. Diagnostic groups associated with pregnancy loss were HLHS and variants (aOR, 3.0 (95% CI, 1.7-5.3)), other single ventricles (aOR, 2.4 (95% CI, 1.1-4.9)) and other (aOR, 0.1 (95% CI, 0-0.97)). Time-to-pregnancy-loss analysis demonstrated a steeper survival curve for cases with an additional fetal diagnosis, indicating a higher rate of pregnancy loss compared to cases with isolated CHD (P < 0.0001). CONCLUSIONS: The risk of pregnancy loss is higher in cases with major fetal CHD compared with the general population and varies according to CHD type and presence of additional fetal diagnoses. Improved understanding of the incidence, risk factors and timing of pregnancy loss in CHD cases should inform patient counseling, antenatal surveillance and delivery planning. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Extracting microplastic decay rates from field data.

Being able to estimate and predict future microplastic distributions in the environment is one of the major challenges of the rapidly developing field of microplastic research. However, this task can only be achieved if our understanding of the decay of individual microplastic particles is significantly enhanced. Here, we show by using a rate equation model that currently available data of size distributions measured at single times cannot provide useful insights into this process. To analyze what data contains more information we generated more complex artificial data mimicking subsequent measurements using a stochastic simulation algorithm. Applying our model to this data revealed the following minimal requirements for future experimental data: (1) data should be collected as time series at identical spots and (2) size measurements should be combined with mass measurements. In contrast to currently available data, flux rates and decay parameters of individual particles can be extracted from such data.

Multicomponent superconducting order parameter in UTe2.

An unconventional superconducting state was recently discovered in uranium ditelluride (UTe2), in which spin-triplet superconductivity emerges from the paramagnetic normal state of a heavy-fermion material. The coexistence of magnetic fluctuations and superconductivity, together with the crystal structure of this material, suggests that a distinctive set of symmetries, magnetic properties, and topology underlie the superconducting state. Here, we report observations of a nonzero polar Kerr effect and of two transitions in the specific heat upon entering the superconducting state, which together suggest that the superconductivity in UTe2 is characterized by a two-component order parameter that breaks time-reversal symmetry. These data place constraints on the symmetries of the order parameter and inform the discussion on the presence of topological superconductivity in UTe2.

Cannabis use while trying to conceive: a prospective cohort study evaluating associations with fecundability, live birth and pregnancy loss.

STUDY QUESTION: Is cannabis use assessed via urinary metabolites and self-report during preconception associated with fecundability, live birth and pregnancy loss? SUMMARY ANSWER: Preconception cannabis use was associated with reduced fecundability among women with a history of pregnancy loss attempting pregnancy despite an increased frequency of intercourse. WHAT IS KNOWN ALREADY: Cannabis use continues to rise despite limited evidence of safety during critical windows of pregnancy establishment. While existing studies suggest that self-reported cannabis use is not associated with fecundability, self-report may not be reliable. STUDY DESIGN, SIZE, DURATION: A prospective cohort study was carried out including 1228 women followed for up to six cycles while attempting pregnancy (2006 to 2012), and throughout pregnancy if they conceived. PARTICIPANTS/MATERIALS, SETTING, METHODS: Women aged 18-40 years with a history of pregnancy loss (n = 1228) were recruited from four clinical centers. Women self-reported preconception cannabis use at baseline and urinary tetrahydrocannabinol metabolites were measured throughout preconception and early pregnancy (up to four times during the study: at baseline, after 6 months of follow-up or at the beginning of the conception cycle, and weeks 4 and 8 of pregnancy). Time to hCG-detected pregnancy, and incidence of live birth and pregnancy loss were prospectively assessed. Fecundability odds ratios (FOR) and 95% CI were estimated using discrete time Cox proportional hazards models, and risk ratios (RRs) and 95% CI using log-binomial regression adjusting for age, race, BMI, education level, baseline urine cotinine, alcohol use and antidepressant use. MAIN RESULTS AND THE ROLE OF CHANCE: Preconception cannabis use was 5% (62/1228), based on combined urinary metabolite measurements and self-report, and 1.3% (11/789) used cannabis during the first 8 weeks of gestation based on urinary metabolites only. Women with preconception cannabis use had reduced fecundability (FOR 0.59; 95% CI 0.38, 0.92). Preconception cannabis use was also associated with increased frequency of intercourse per cycle (9.4 ± 7 versus 7.5 ± 7 days; P = 0.02) and higher LH (percentage change 64%, 95% CI 3, 161) and higher LH:FSH ratio (percentage change 39%, 95% CI 7, 81). There were also suggestive, though imprecise, associations with anovulation (RR 1.92, 95% CI 0.88, 4.18), and live birth (42% (19/45) cannabis users versus 55% (578/1043) nonusers; RR 0.80, 95% CI 0.57, 1.12). No associations were observed between preconception cannabis use and pregnancy loss (RR 0.81, 95% CI 0.46, 1.42). Similar results were observed after additional adjustment for parity, income, employment status and stress. We were unable to estimate associations between cannabis use during early pregnancy and pregnancy loss due to limited sample size. LIMITATIONS, REASONS FOR CAUTION: Owing to the relatively few cannabis users in our study, we had limited ability to make conclusions regarding live birth and pregnancy loss, and were unable to account for male partner use. While results were similar after excluding smokers, alcohol use and any drug use in the past year, some residual confounding may persist due to these potential co-exposures. WIDER IMPLICATIONS OF THE FINDINGS: These findings highlight potential risks on fecundability among women attempting pregnancy with a history of pregnancy loss and the need for expanded evidence regarding the reproductive health effects of cannabis use in the current climate of increasing legalization. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (Contract numbers: HHSN267200603423, HHSN267200603424, HHSN267200603426, HHSN275201300023I). Jeannie G. Radoc has been funded by the National Institutes of Health Medical Research Scholars Program, a public-private partnership supported jointly by the National Institutes of Health and generous contributions to the Foundation for the National Institutes of Health from the Doris Duke Charitable Foundation (DDCF Grant # 2014194), Genentech, Elsevier, and other private donors. The authors report no conflict of interest in this work and have nothing to disclose. TRIAL REGISTRATION NUMBER: Clinicaltrials.gov NCT00467363.

Quantification of microplastics: Which parameters are essential for a reliable inter-study comparison?

Inconsistencies in microplastic quantification are a problem in current microplastic research, leading to difficulties in inter-study comparability. This study proposes a guideline for consistent quantification of microplastic distributions. It contains specific recommendations on how to quantify common microplastic particle parameters, such as size or shape. These recommendations are based on how reliably a parameter can be measured and its importance for inter-study comparability. Furthermore, our study proposes a multidimensional vector approach, where one vector contains the information for the microplastic distribution in one sample. In this way geometric and statistical means can be used to quantitatively compare different studies. In particular, in combination with our proposed quantification procedure, a meaningful comparison of microplastic distributions across different studies becomes possible. Ultimately, this allows comparable long-term and global scale assessments, as well as the development of modeling approaches.

Marijuana use in young mothers and adverse pregnancy outcomes: a retrospective cohort study.

OBJECTIVE: To evaluate the association between marijuana use and a composite adverse pregnancy outcome using biological sampling. DESIGN: Retrospective cohort study. SETTING: Single tertiary center. POPULATION: Young women (13-22 years old) with singleton, non-anomalous pregnancies delivered from September 2011 to May 2017. METHODS: Exposure was defined as marijuana detected on universal urine toxicology testing or by self-report. Multivariable logistic regression modelling was used to estimate the effect of any marijuana use on the primary composite outcome. The effect of marijuana exposure was also estimated for self-reported use, toxicology-detected use, and multiple use detected by toxicology. MAIN OUTCOME MEASURE: The primary composite outcome included spontaneous preterm birth, hypertensive disorders of pregnancy, stillbirth, or small for gestational age. RESULTS: Of 1206 pregnant young women, 17.5% (n = 211) used marijuana. Among the women who used marijuana, 8.5% (n = 18) were identified by self-report alone, 63% (n = 133) by urine toxicology alone, and 28.4% (n = 60) by both. Urine toxicology testing results were available for 1092 (90.5%) births. The composite outcome occurred more frequently in pregnancies exposed to marijuana (46 versus 34%, P < 0.001). This remained significant after adjusting for race/ethnicity and tobacco in the multivariable model (adjusted OR 1.50, 95% CI 1.09-2.05). When marijuana exposure was defined by self-report only, the association with adverse pregnancy outcome became non-significant (adjusted OR 1.01, 95% CI 0.62-1.64). CONCLUSION: In a population of young women with nearly universal biological sampling, marijuana exposure was associated with adverse pregnancy outcomes. The heterogeneity of findings in existing studies evaluating the impact of marijuana on mothers and neonates may result from the incomplete ascertainment of exposure. TWEETABLE ABSTRACT: Marijuana use, as detected by universal urine testing, was associated with a composite adverse pregnancy outcome among young mothers.

Demethylation of the hypoxia induction factor 1 binding site of GPX3 at excess blood ammonia in propionic acidemia.

OBJECTIVES: Elevated levels of metabolites such as ammonia and propionylcarnitine in propionic acidemia (PA) lead to an increased reactive oxygen species (ROS) production which could activate and stabilize the epigenetic regulated hypoxia-inducible factor-1α (HIF-1α). In order to evaluate the DNA methylation status of the HIF-1α binding site in PA, we investigated the antioxidant gluthatione peroxidase 3 gene (GPX3) promoter region. DESIGN AND METHODS: Using leukocyte DNA extracted from bloodspots collected 2-4 days after birth from diet free newborns, the cytosine phosphodiester bond guanine (CpG) dinucleotides of a HIF-1α binding site (CGTTTTTTACG) in the promoter region of GPX3 was retrospectively analysed. Patients included 7 PA. and 7 healthy controls (KO) respectively. RESULTS: A demethylated TGTTTTTTATG allele was detected in 3 PA patients with blood ammonia (NH3) concentrations of 500, 595, and 987 umol/L respectively; a demethylated/partial methylated TGTTTTTTAC/TG allele in 4 PA patients (2 PA with blood NH3 = 213, 271 umol/L respectively); a partial methylated C/TGTTTTTTAC/TG allele in 5 healthy controls respectively; a partial methylated/methylated C/TGTTTTTTACG allele in 2 healthy controls. CONCLUSION: Our results suggest that at excess NH3, the DNA methylation status of the HIF-1α binding site of GPX3 in newborns with PA is demethylated (TGTTTTTTATG allele). However, the demethylated allele has to be confirmed as a statistically significant change in more patients.

Plasma lipidome reveals critical illness and recovery from human Ebola virus disease.

Ebola virus disease (EVD) often leads to severe and fatal outcomes in humans with early supportive care increasing the chances of survival. Profiling the human plasma lipidome provides insight into critical illness as well as diseased states, as lipids have essential roles as membrane structural components, signaling molecules, and energy sources. Here we show that the plasma lipidomes of EVD survivors and fatalities from Sierra Leone, infected during the 2014-2016 Ebola virus outbreak, were profoundly altered. Focusing on how lipids are associated in human plasma, while factoring in the state of critical illness, we found that lipidome changes were related to EVD outcome and could identify states of disease and recovery. Specific changes in the lipidome suggested contributions from extracellular vesicles, viremia, liver dysfunction, apoptosis, autophagy, and general critical illness, and we identified possible targets for therapies enhancing EVD survival.

Low-dose aspirin for pre-eclampsia prevention in twins with elevated human chorionic gonadotropin.

OBJECTIVE: The objective of the study is to evaluate low-dose aspirin (LDA) for pre-eclampsia prevention in twin gestations with elevated maternal serum human chorionic gonadotropin (hCG). STUDY DESIGN: Secondary analysis of the Maternal-Fetal Medicine Units High-Risk Aspirin trial for pre-eclampsia prevention. A threshold hCG level for predicting pre-eclampsia was identified in placebo-randomized patients. Pre-eclampsia incidence and time of onset were compared between treatment groups, overall and by hCG threshold category. RESULTS: Pre-eclampsia incidence was lower with LDA than with placebo (6% vs 16%, OR 0.32, 95% CI 0.12 to 0.82). An hCG threshold of 29.96 IU ml(-1) best predicted pre-eclampsia. In patients with hCG <29.96 IU ml(-1), the differences in pre-eclampsia incidence or time of onset were not significant. In patients with hCG >29.96 IU ml(-1), LDA was associated with lower pre-eclampsia incidence than placebo (6% vs 23%, OR 0.21, 95% CI 0.06 to 0.79) and delayed onset. CONCLUSION: Twin gestations with elevated hCG levels may benefit from LDA for pre-eclampsia prevention.

[Superficial acral fibromyxoma in a sub-matricial location: An unusual variant]. / Fibromyxome acral superficiel de localisation sous-matricielle : une forme clinique inhabituelle.

BACKGROUND: Superficial acral fibromyxoma (SAFM) is a benign soft tissue tumor located in the acral areas, particularly the peri- and sub-ungueal areas. Sub-matricial localisations have not been reported to date. PATIENTS AND METHODS: We report herein the clinical and pathological presentation of three cases of SAFM located solely under the matrix. The patients presented with pseudo-clubbing, onychogryphosis or triangular macrolunula. The histopathological appearance was characteristic. DISCUSSION: SAFM is a slow-growing, skin-colored, firm nodule, located chiefly on the digits or the toes, and especially in the nail area. It may or may not be painful. Microscopically, it presents as a relatively well-circumscribed but unencapsulated dermal tumor, composed of spindle shaped cells integrated in a myxocollagenic matrix, sometimes invading the subcutis. Tumor cells diffusely express CD34. A conservative surgical approach is recommended. Both clinicians and pathologists should be aware of this entity in order to avoid misdiagnosis, which can lead to unwarranted mutilating surgery. CONCLUSION: Sub-matricial localisation of SAFM is extremely rare and may present as pseudo-clubbing, isolated onychogryphosis or a triangular macrolunula. A conservative surgical approach should be recommended.

Cost-effectiveness of prenatal screening strategies for congenital heart disease.

OBJECTIVE: The economic implications of strategies to improve prenatal screening for congenital heart disease (CHD) in low-risk mothers have not been explored. The aim was to perform a cost-effectiveness analysis of different screening methods. METHODS: We constructed a decision analytic model of CHD prenatal screening strategies (four-chamber screen (4C), 4C + outflow, nuchal translucency (NT) or fetal echocardiography) populated with probabilities from the literature. The model included whether initial screens were interpreted by a maternal-fetal medicine (MFM) specialist and different referral strategies if they were read by a non-MFM specialist. The primary outcome was the incremental cost per defect detected. Costs were obtained from Medicare National Fee estimates. A probabilistic sensitivity analysis was undertaken on model variables commensurate with their degree of uncertainty. RESULTS: In base-case analysis, 4C + outflow referred to an MFM specialist was the least costly strategy per defect detected. The 4C screen and the NT screen were dominated by other strategies (i.e. were more costly and less effective). Fetal echocardiography was the most effective, but most costly. On simulation of 10 000 low-risk pregnancies, 4C + outflow screen referred to an MFM specialist remained the least costly per defect detected. For an additional $580 per defect detected, referral to cardiology after a 4C + outflow was the most cost-effective for the majority of iterations, increasing CHD detection by 13 percentage points. CONCLUSIONS: The addition of examination of the outflow tracts to second-trimester ultrasound increases detection of CHD in the most cost-effective manner. Strategies to improve outflow-tract imaging and to refer with the most efficiency may be the best way to improve detection at a population level.

Effect of antioxidants and ACE inhibition on chemical modification of proteins and progression of nephropathy in the streptozotocin diabetic rat.

AIMS/HYPOTHESIS: This study was designed to determine whether inhibition of formation of AGE and advanced lipoxidation end-products (ALE) is a mechanism of action common to a diverse group of therapeutic agents that limit the progress of diabetic nephropathy. We compared the effects of the ACE inhibitor enalapril, the antioxidant vitamin E, the thiol compound lipoic acid, and the AGE/ALE inhibitor pyridoxamine on the formation of AGE/ALE and protection against nephropathy in streptozotocin diabetic rats. METHODS: Renal function and AGE/ALE formation were evaluated in rats treated with the agents listed above. Plasma was monitored monthly for triglycerides, cholesterol, creatinine and TNF-alpha, and 24-h urine samples were collected for measurement of albumin and total protein excretion. After 29 weeks, renal expression of mRNA for extracellular matrix proteins was measured, and AGE/ALE were quantified in skin and glomerular and tubular collagen. RESULTS: Diabetic animals were both hyperglycaemic and dyslipidaemic, and showed evidence of early nephropathy (albuminuria, creatinaemia). All interventions limited the progression of nephropathy, without affecting glycaemia. The order of efficacy was: pyridoxamine (650 mg.kg(-1).day(-1)) > vitamin E (200 mg.kg(-1).day(-1)) > lipoic acid (93 mg.kg(-1).day(-1)) approximately enalapril (35 mg.kg(-1).day(-1)). Pyridoxamine also significantly inhibited AGE/ALE accumulation in tissues; effects of other agents were mixed, but the degree of renoprotection was consistent with their effects on AGE/ALE formation. CONCLUSIONS/INTERPRETATION: All interventions inhibited the progression of nephropathy at the doses studied, but the maximal benefit was achieved with pyridoxamine, which also limited dyslipidaemia and AGE/ALE formation. These experiments indicate that the more effective the renoprotection, the greater the inhibition of AGE/ALE formation. For optimal protection of renal function, it would be beneficial to select drugs whose mechanism of action includes inhibition of AGE/ALE formation.

Role of lipids in chemical modification of proteins and development of complications in diabetes.

Hyperglycaemia is the major risk factor for the development of complications in both Type I and Type II diabetes; however, there is growing evidence from several clinical trials that dyslipidaemia, including hypertriglyceridaemia, is a significant and independent risk factor for diabetic complications. In this paper, we propose that chemical modification of proteins by lipids may be a underlying pathogenic mechanism linking dyslipidaemia to diabetic complications. Thus the major AGEs (advanced glycation end-products) in tissues, such as carboxymethyl-lysine, carboxyethyl-lysine and hydroimidazolones, may, in fact, be ALEs (advanced lipoxidation end-products), derived from lipids. Increased lipid peroxidation and accelerated ALE formation, possibly catalysed by hyperglycaemia and oxidative stress, may be the mechanistic link between dyslipidaemia and diabetic complications. If correct, this proposal would suggest that inhibition or reversal of glycation, which is a central theme of this symposium, may not be sufficient for protection against diabetic complications.

Mass spectrometric analysis of glucose-modified ribonuclease.

RNase A (1 mM) was incubated with glucose (0.4 M) at 37 degrees C for up to 14 days in phosphate buffer (0.2 M, pH 7.4), digested with trypsin and analysed by LC-MS. The major sites of fructoselysine formation were Lys(1), Lys(7), Lys(37) and Lys(41). Three of these sites (Lys(7), Lys(37) and Lys(41)) were also the major sites of N epsilon-(carboxymethyl)lysine formation.

Molecular characterisation of antidepressant effects in the mouse brain using gene expression profiling.

Antidepressants are widely used for the treatment of psychiatric disorders, including depression and anxiety. Although they are efficient drugs, there are several unsolved questions regarding their clinical pharmacology. Furthermore, the molecular mechanisms of action of antidepressants are still poorly understood and the molecular targets and pathways remain to be identified. To address these issues, we performed a gene expression analysis in mice treated with two commonly used antidepressants with differing pharmacology (paroxetine or mirtazapine) for 1, 7 or 28 days. We quantified the effects of these treatments on gene expression in the mouse brain with cDNA-microarrays containing 3624 expressed sequence tags (ESTs) representing murine genes expressed in the brain. We found that both drugs led to downregulation of four common genes. In addition, although it was possible to identify common targets for the two drugs, the expression profiles of the drugs differed in a fundamental manner, and the longer the treatment duration, the greater the difference in the profiles. These findings suggest that antidepressants with different pharmacologies can share molecular targets even though the primary pathways at which they act are different.

c-erbB-2 expression in small-cell lung cancer is associated with poor prognosis.

Small-cell lung cancer (SCLC) carries a bad prognosis despite good initial response to chemotherapy. It is therefore important to identify molecular markers that influence survival as potential new therapeutic targets. In our study, expression of the tyrosine kinase c-erbB-2 (HER2/neu) receptor in tumor tissues of 107 consecutive newly diagnosed patients with primary SCLC was quantified using a monoclonal antibody directed against the c-terminal domain of c-erbB-2. A clear-cut positive expression of c-erbB-2 was observed in 13% of patients. Surprisingly, c-erbB-2 was an independent prognostic factor (RR = 2.16; p = 0.014) when a proportional-hazard model was adjusted to stage (limited vs. extensive disease) and performance status (WHO I-IV), the most relevant clinical parameters. Similarly, a significant association between c-erbB-2 and survival was obtained if a larger number of clinical parameters were included into the analysis, namely response to chemotherapy, TNM stage, lactate dehydrogenase (LDH), neuron-specific enolase (NSE), gender and age (p = 0.033). Interestingly, c-erbB-2 expression was more relevant for patients with advanced tumors. In the subgroup of patients with bad performance status (WHO II-IV), median survival of patients with undetectable c-erbB-2 expression was 274 days compared with only 23 days for patients with clear-cut positive c-erbB-2 immunohistochemistry (p = 0.0031; log-rank test). Similar results were obtained for patients with extensive disease (p = 0.028) and high TNM stages (T>2 or N>1 or M1; p < 0.068, all comparisons). In contrast, c-erbB-2 expression was not associated with survival in patients with limited disease (p = 0.97), low TNM stages (p > 0.56, all comparisons) and good performance status (p = 0.97). In conclusion, c-erbB-2 is expressed in more than 10% of SCLC. Expression of c-erbB-2 is an independent prognostic factor of survival. The effect of c-erbB-2 expression seems to become more important in advanced stages of the disease. Since c-erbB-2 is a therapeutical target in other types of cancer, further studies to identify the role of c-erbB-2 in SCLC are clearly warranted.

Greenhouse tests on resistance management of Bt transgenic plants using refuge strategies.

Experimental evaluation of the effectiveness of resistance management tactics is vital to help provide guidelines for the deployment of transgenic insecticidal crops. Transgenic broccoli expressing a Cry1Ac gene of Bacillus thuringiensis (Bt) and the diamondback moth, Plutella xylostella (L.), were used in greenhouse tests to evaluate the influence of size and placement of nontransgenic refuge plants on changes in resistance allele frequency and pest population growth. In the first test with an initial Cry1Ac-resistance (R) allele frequency of 0.007, P. xylostella were introduced into cages with the following treatments: 0, 3.3, 10, 20, and 100% refuge plants. Results after four generations showed that resistance could be delayed by increasing the proportion of refuge plants in the cage. Population growth was also influenced by refuge size with the highest populations occurring in treatments that had either no refuge plants or all refuge plants. In the second test, we evaluated the effect of refuge placement by comparing 20% separate and 20% mixed refuges. P. xylostella with an initial frequency of resistant alleles at 0.0125 were introduced into cages and allowed to cycle; later generations were evaluated for resistance and population growth. Separating the refuge had a pronounced effect on delaying resistance and slowing establishment of resistant larvae on Bt plants. Combining information from both trials, we found a strong negative correlation between the number of larvae on Bt plants and the mortality of the population in leaf dip bioassays. Results from larval movement studies showed that separate refuges delayed resistance better than mixed refuges because they conserved relatively more susceptible alleles than R alleles and did not increase the effective dominance of resistance.

Field tests on managing resistance to Bt-engineered plants.

Several important crops have been engineered to express toxins of Bacillus thuringiensis (Bt) for insect control. In 1999, US farmers planted nearly 8 million hectares (nearly 20 million acres) of transgenic Bt crops approved by the EPA. Bt-transgenic plants can greatly reduce the use of broader spectrum insecticides, but insect resistance may hinder this technology. Present resistance management strategies rely on a "refuge" composed of non-Bt plants to conserve susceptible alleles. We have used Bt-transgenic broccoli plants and the diamondback moth as a model system to examine resistance management strategies. The higher number of larvae on refuge plants in our field tests indicate that a "separate refuge" will be more effective at conserving susceptible larvae than a "mixed refuge" and would thereby reduce the number of homozygous resistant (RR) offspring. Our field tests also examined the strategy of spraying the refuge to prevent economic loss to the crop while maintaining susceptible alleles in the population. Results indicate that great care must be taken to ensure that refuges, particularly those sprayed with efficacious insecticides, produce adequate numbers of susceptible alleles. Each insect/Bt crop system may have unique management requirements because of the biology of the insect, but our studies validate the need for a refuge. As we learn more about how to refine our present resistance management strategies, it is important to also develop the next generation of technology and implementation strategies.