Differential gene expression of neonatal and adult DRG neurons correlates with the differential sensitization of TRPV1 responses to nerve growth factor

Cultures of neonatal and adult dorsal root ganglion (DRG) neurons are commonly used in in vitro models to study the ion channels and signaling events associated with peripheral sensation under various conditions. Differential responsiveness between neonatal and adult DRG neurons to physiological or pathological stimuli suggests potential differences in their gene expression profiles. We performed a microarray analysis of cultured adult and neonatal rat DRG neurons, which revealed distinct gene expression profiles especially of ion channels and signaling molecules at the genomic level. For example, Ca²⁺-stimulated adenylyl cyclase (AC) isoforms AC3 and AC8, PKCδ and CaMKIIα, the voltage-gated sodium channel β1 and β4, and potassium channels K_v1.1, K_v3.2, K_v4.1, K_v9.1, K_v9.3, K_ir3.4, K_ir7.1, K_2P1.1/TWIK-1 had significantly higher mRNA expression in adult rat DRG neurons, while Ca²⁺-inhibited AC5 and AC6, sodium channel Na_v1.3 α subunit, potassium channels K_ir6.1, K_2P10.1/TREK-2, calcium channel Ca_v2.2 α1 subunit, and its auxiliary subunits β1 and β3 were conversely down regulated in adult neurons. Importantly, higher adult neuron expression of ERK1/2, PI3K/P110α, but not of TRPV1 and TrkA, was found and confirmed by PCR and western blot. These latter findings are consistent with the key role of ERK and PI3K signaling in sensitization of TRPV1 by NGF and may explain our previously published observation that adult, but not neonatal, rat DRG neurons are sensitized by NGF.     

Children's Oncology Group's 2013 blueprint for research: Survivorship and outcomes

Improvements in the treatment of childhood cancer have resulted in over 360,000 survivors of childhood cancer in the U.S. There is now a heightened recognition of the need to reduce treatment‐related sequelae and optimize the quality of life of children treated for cancer. Survivorship studies conducted in the cooperative group setting have provided us with important information on long‐term intellectual function, organ toxicity, reproductive outcomes, second cancers, late mortality, and disparities in outcomes. Ongoing health education initiatives have helped standardize the follow‐up care for childhood cancer survivors and facilitate the early transfer of health‐related information to patients, families, and healthcare providers. Pediatr Blood Cancer 2013; 60: 1063–1068. © 2012 Wiley Periodicals, Inc.     

UGT1A1 is a major locus influencing bilirubin levels in African Americans

Total serum bilirubin is associated with several clinical outcomes, including cardiovascular disease, diabetes and drug metabolism. We conducted a genome-wide association study in 619 healthy unrelated African Americans in an attempt to replicate reported findings in Europeans and Asians and to identify novel loci influencing total serum bilirubin levels. We analyzed a dense panel of over two million genotyped and imputed SNPs in additive genetic models adjusting for age, sex, and the first two significant principal components from the sample covariance matrix of genotypes. Thirty-nine SNPs spanning a 78 kb region within the UGT1A1 displayed P-values <5 × 10⁻⁸. The lowest P-value was 1.7 × 10⁻²² for SNP rs887829. None of SNPs in the UGT1A1 remained statistically significant in conditional association analyses that adjusted for rs887829. In addition, SNP rs10929302 located in phenobarbital response enhancer module was significantly associated with bilirubin level with a P-value of 1.37 × 10⁻¹¹; this enhancer module is believed to have a critical role in phenobarbital treatment of hyperbilirubinemia. Interestingly, the lead SNP, rs887829, is in strong linkage disequilibrium (LD) (r²≥0.74) with rs10929302. Taking advantage of the lower LD and shorter haplotypes in African-ancestry populations, we identified rs887829 as a more refined proxy for the causative variant influencing bilirubin levels. Also, we replicated the reported association between variants in SEMA3C and bilirubin levels. In summary, UGT1A1 is a major locus influencing bilirubin levels and the results of this study promise to contribute to understanding of the etiology and treatment of hyperbilirubinaemia in African-ancestry populations.     

The Fanconi anaemia pathway orchestrates incisions at sites of crosslinked DNA

Fanconi anaemia (FA) is a rare, autosomal recessive, genetically complex, DNA repair deficiency syndrome in man. Patients with FA exhibit a heterogeneous spectrum of clinical features. The most significant and consistent phenotypic characteristics are stem cell loss, causing progressive bone marrow failure and sterility, diverse developmental abnormalities and a profound predisposition to neoplasia. To date, 15 genes have been identified, biallelic disruption of any one of which results in this clinically defined syndrome. It is now apparent that all 15 gene products act in a common process to maintain genome stability. At the molecular level, a fundamental defect in DNA repair underlies this complex phenotype. Cells derived from FA patients spontaneously accumulate broken chromosomes and exhibit a marked sensitivity to DNA-damaging chemotherapeutic agents. Despite complementation analysis defining many components of the FA DNA repair pathway, no direct link to DNA metabolism was established until recently. First, it is now evident that the FA pathway is required to make incisions at the site of damaged DNA. Second, a specific component of the FA pathway has been identified that regulates nucleases previously implicated in DNA interstrand crosslink repair. Taken together, these data provide genetic and biochemical evidence that the FA pathway is a bona fide DNA repair pathway that directly mediates DNA repair transactions, thereby elucidating the specific molecular defect in human Fanconi anaemia.     

Neovascularization and recurrent varicose veins: more histologic and ultrasound evidence

BACKGROUND: The recurrence of varicose veins is a common and costly consequence of varicose vein surgery. Despite the long history and vast experience of varicose vein surgery, the exact cause of recurrence is still unknown. This study aims to investigate the cause of recurrence further by correlating findings from duplex ultrasound scans, resin casts, and histologic investigation at the recurrence of the saphenofemoral junction. In particular, frequency and neovascularization are evaluated. METHOD: Forty-nine saphenofemoral junctions (SFJs) from 42 patients who presented for re-operation on their varicose veins were examined with duplex ultrasound and physiologic air plethysmography tests before surgery. All patients had reflux at the groin for which surgery was carried out. Specimens taken during surgery were sectioned and stained for conventional histology and immunohistology, and 5 specimens were infused with resin to form a cast of the venous vasculature. RESULTS: All but 3 re-operation specimens (94%) showed multiple vessels at the stump site of the previous SFJ ligation. Neovascular channels of variable size, number, and tortuosity accounted for the ultrasound appearances and reflux to recurrent varicosities in the vast majority of specimens. These new vessels connected to the common femoral vein at the site of the previous SFJ. In 2 incompetent junctions without femoral vein involvement, while small vessels were seen surrounding the femoral stump scar, ultrasound and histology confirmed both neovascular and residual (enlarged collateral) connections from epigastric and pudendal vessels into the thigh. CONCLUSION: Neovascularisation is the major cause for ultrasound-confirmed recurrence of reflux in the groin following varicose vein surgery.