Fundamental approaches to the study of zebrafish nutrition

The value of the zebrafish model has been well established. However, culture variability within and among laboratories remains a concern, particularly as it relates to nutrition. Investigators using rodent models addressed this concern several decades ago and have developed strict nutritional regimes to which their models adhere. These investigators decreased the variability associated with nutrition in most studies by developing standardized reference and open formulation diets. Zebrafish investigators have not embraced this approach. In this article, we address the problems associated with the lack of nutritional information and standardization in the zebrafish research community. Based on the knowledge gained from studies of other animals, including traditional research models, other fish species, domesticated and companion animals, and humans, we have proposed an approach that seeks to standardize nutrition research in zebrafish. We have identified a number of factors for consideration in zebrafish nutrition studies and have suggested a number of proposed outcomes. The long term-goal of nutrition research will be to identify the daily nutritional requirements of the zebrafish and to develop appropriate standardized reference and open formulation diets.

First Report of Verticillium Wilt on Lettuce (Lactuca sativa) in Washington Caused by Verticillium tricorpus

Symptoms of Verticillium wilt were observed on lettuce (Lactuca sativa L.) harvested from high tunnel and open field experimental plots in annual, consecutive spring plantings in western Washington from 2010 to 2012. Leaves had v-shaped, chlorotic lesions, and yellow or brown vascular tissue was noted in the crowns. Total disease incidence increased from 0.2% in 2010 to 1.9% in 2011 and to 14.4% in 2012. Verticillium spp. obtained from infected crown tissues and cultured on half-strength potato dextrose agar medium produced yellow pigment, black microsclerotia, white mycelia, tan chlamydospores, and uniseptate conidia averaging 10.6 × 3.7 μm. Isolates were identified tentatively as Verticillium tricorpus I. (3). Three isolates, Vt.Ls.2010, Vt.Ls.2011-1, and Vt.Ls.2011-2, were evaluated for pathogenicity on 4-week-old 'Coastal Star' seedlings in two greenhouse trials. In Trial I, four replicates of two duplicate plants per each isolate, and in Trial II, five replicates of one plant per each isolate were inoculated with conidial suspensions adjusted to 2.0 × 10⁶ and 5.0 × 10⁶ conidia/ml, respectively. Additionally, in each trial, two sets of control treatments of five plants each were inoculated with either an isolate of V. dahliae at the same conidial concentration or with sterile water. Root tips were cut and exposed to the suspensions for 5 s, then seedlings were transplanted into Sunshine Mix #1 (SunGro Horticulture Distribution Inc., Bellevue, WA), and kept in a greenhouse at 17.7 ± 3.4°C. Plants were harvested 8 to 9 weeks post-inoculation, and symptoms were rated visually. Vt.Ls.2010, Vt.Ls.2011-1, and Vt.Ls.2011-2 caused chlorosis and vascular discoloration on 25, 13, and 13% of the plants in Trial I; and 40, 60, and 20% of plants in Trial II, respectively. V. dahliae caused similar symptoms on 25 and 40% of the plants in the two trials, respectively, but these plants had greater intensity and length of vascular discoloration compared with the three test isolates. None of the water control plants were symptomatic. All V. tricorpus isolates were recovered from inoculated plants, and colony morphologies were similar to the original isolates. The internal transcribed spacer (ITS) rDNA of isolate Vt.Ls.2010 was amplified with ITS4 and ITS6 primer sets. ITS rDNA sequences between Vt.Ls.2010 and two isolates of V. tricorpus in GenBank (Accession Nos. FJ900211 and AB353343) were 100% identical. V. tricorpus is considered a weak pathogen of lettuce crops in California (2), but authors in Japan recently reported pathogenic isolates of V. tricorpus on lettuce (4). To our knowledge, this is the first report of Verticillium wilt caused by V. tricorpus in Washington. Lettuce is the number two crop grown in high tunnels in the United States (1), and cropping lettuce continuously in them can increase the risk of this and other soilborne pathogens. References: (1) E. E. Carey et al. HortTechnology 19:37, 2009. (2) Q.-M. Qin et al. Plant Dis. 92:69, 2008. (3) H. C. Smith. N. Z. J. Agric. Res. 8:450, 1965. (4) T. Usami et al. J. Gen. Plant Pathol. 77:17, 2010.

Pilocytic astrocytoma mimicking craniopharyngioma: a case series

Although they are one of the most common brain tumours in childhood, pilocytic astrocytomas are rare in adulthood. We report a series of three pilocytic astrocytomas presenting as an intra/suprasellar mass in the fourth to sixth decades of life. All three radiologically mimicked the appearance of a craniopharyngioma, thus representing a potential radiological and diagnostic pitfall. In this series all three patients underwent successful operative management and have remained well throughout follow-up. The majority of information concerning pilocytic astrocytomas is derived from paediatric populations and so only limited and often conflicting data exist for pilocytic astrocytomas developing in adulthood. Decisions regarding treatment of pilocytic astrocytomas in adults must be made on a multidisciplinary, case-by-case basis.

Genetic variation in radiation and platinum pathways predicts severe acute radiation toxicity in patients with esophageal adenocarcinoma treated with cisplatin-based preoperative radiochemotherapy: results from the Eastern Cooperative Oncology Group

PURPOSE

Germline genetic variations may partly explain the clinical observation that normal tissue tolerance to radiochemotherapy varies by individual. Our objective was to evaluate the association between single-nucleotide polymorphisms (SNPs) in radiation/platinum pathways and serious treatment-related toxicity in subjects with esophageal adenocarcinoma who received cisplatin-based preoperative radiochemotherapy.

METHODS

In a multicenter clinical trial (E1201), 81 eligible treatment-naïve subjects with resectable esophageal adenocarcinoma received cisplatin-based chemotherapy concurrent with radiotherapy, with planned subsequent surgical resection. Toxicity endpoints were defined as grade ≥3 radiation-related or myelosuppressive events probably or definitely related to therapy, occurring during or up to 6 weeks following the completion of radiochemotherapy. SNPs were analyzed in 60 subjects in pathways related to nucleotide/base excision- or double stranded break repair, or platinum influx, efflux, or detoxification.

RESULTS

Grade ≥3 radiation-related toxicity (mostly dysphagia) and myelosuppression occurred in 18 and 33% of subjects, respectively. The variant alleles of the XRCC2 5' flanking SNP (detected in 28% of subjects) and of GST-Pi Ile-105-Val (detected in 65% of subjects) were each associated with higher odds of serious radiation-related toxicity compared to the major allele homozygote (47% vs. 9%, and 31% vs. 0%, respectively; P = 0.005). No SNP was associated with myelosuppression.

CONCLUSIONS

This novel finding in a well-characterized cohort with robust endpoint data supports further investigation of XRCC2 and GST-Pi as potential predictors of radiation toxicity.

Abstract P3-11-16: First Pregnancy Events Determine Future Breast Density Independent of Systemic Sex Steroid Levels

Introduction: Pregnancy outcomes (e.g., preterm birth, preeclampsia, and birthweight) have been associated with altered breast cancer risk. Hypotheses linking pregnancy outcomes and subsequent breast cancer risk include persistent changes in endogenous hormones and/or imprinted changes in mammary gland differentiation and morphology. Limited information exists on the relationship between pregnancy characteristics and mammographic density. The Marin Women's Study (MWS) was initiated in 2006 to examine breast cancer in a mammography population in an area with high breast cancer incidence (Marin County). MWS enrollment occurs at mammography sites in Marin County that participate in the San Francisco Mammography Registry, one of seven registries included in the National Cancer Institute Breast Cancer Surveillance Consortium. The MWS includes ∼14,000 participants, covering ∼80% of the County's mammography screening population. An analysis was undertaken using MWS data to examine the relationship between first pregnancy outcomes and later life mammographic density, controlling for standard breast cancer risk factors.

Methods: Reproductive characteristics were self-reported on the MWS questionnaire at the time of mammogram. Volumetric compositional breast density (BDsxa) using single X-ray absorptiometry techniques (SXA) was measured on screening digital mammography examinations measured by the San Francisco Mammography Registry. Systemic sex steroid hormone levels were measured on a single early morning saliva sample. Women were excluded if they reported a history of breast cancer, if their first birth was a multi-fetal gestation, if they reported using antiestrogens within the five years preceding the questionnaire, or if they were missing data on any of the model variables. Robust regression models were controlled for current age, body mass index (BMI), race, education, physical activity, alcohol consumption, smoking, family history of breast cancer, hysterectomy, menopausal status, and hormone use at the time of mammography.

Results: The study population included 2162 parous women. Using multivariable regression we found that a history of gestational hypertension during first pregnancy was associated with a statistically significant decrease in BDsxa (b=-0.29, p=0.01), while each month of breastfeeding after first birth was associated with a statistically significant increase in BDsxa (b=0.01, p=0.01). Menopausal status (pre-and peri-vs. postmenopausal) and age at first birth (<30 vs. 30+ y) modified these associations. Reproductive factors explained a greater proportion of the variability in BDsxa in premenopausal than in postmenopausal women (40% vs 31%), and a greater proportion of variability in those with a later age at first birth (45% of age 30+ y vs. 36% of age <30y). Salivary hormone levels (E2, P, T, DHEA) were not consistently associated with breast density.

Conclusions: This analysis demonstrates that a woman's first pregnancy outcomes may determine future breast density, and that this association varies by age at first birth and menopausal status at the time of breast density measurement. These findings suggest that pregnancy may exert its influence on future breast cancer risk via changes in breast morphology and density.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-11-16.