Opposing aging-related shift of excitatory dopamine D1 and inhibitory D3 receptor protein expression in striatum and spinal cord.

Normal aging is associated with a decrease in motor function, a concomitant increase in muscle stiffness and tone, and a decrease in dopamine (DA) levels in the spinal cord. The striatum plays a critical role in the control of motor function, and it receives strong DA innervation from the substantia nigra. However, locomotor activity also requires the activation of motoneurons in the lumbar spinal cord, which in the mouse express all five DA receptor subtypes (D1-D5). Of these, the D3 receptor (D3R) expresses the highest affinity to DA and mediates inhibitory actions, while activation of the lower-affinity D1 receptor (D1R) system promotes excitatory effects. To test whether the aging-related decrease in DA levels is associated with corresponding changes in DA receptor protein expression levels, we probed with Western blot and immunohistochemical techniques for D1R and D3R protein expression levels over the normal life span of the mouse. We found that with age D1R expression levels increased in both striatum and spinal cord, while D3R expression levels remained stable in the striatum or slightly decreased in the spinal cord. The resulting D1-to-D3 ratio indicates a strong upregulation of D1R-mediated pathways in old animals, which is particularly pronounced in the lumbar spinal cord. These data suggest that aging may be associated with a shift in DA-mediated pathways in striatum and spinal cord, which in turn could be an underlying factor in the emergence of aging- and DA-related motor dysfunctions such as Parkinson's disease or Restless Legs Syndrome (RLS).

Late gastrointestinal tissue effects after hypofractionated radiation therapy of the pancreas.

BACKGROUND: To consolidate literature reports of serious late gastrointestinal toxicities after hypofractionated radiation treatment of pancreatic cancer and attempt to derive normal tissue complication probability (NTCP) parameters using the Lyman-Kutcher-Burman model. METHODS: Published reports of late grade 3 or greater gastrointestinal toxicity after hypofractionated treatment of pancreatic cancer were reviewed. The biologically equivalent dose in 1.8 Gy fractions was calculated using the EQD model. NTCP parameters were calculated using the LKB model assuming 1-5% of the normal tissue volume was exposed to the prescription dose with α/ß ratios of 3 or 4. RESULTS: A total of 16 human studies were examined encompassing a total of 1160 patients. Toxicities consisted of ulcers, hemorrhages, obstructions, strictures, and perforations. Non-hemorrhagic and non-perforated ulcers occurred at a rate of 9.1% and were the most commonly reported toxicity. Derived NTCP parameter ranges were as follows: n = 0.38-0.63, m = 0.48-0.49, and TD50 = 35-95 Gy. Regression analysis showed that among various study characteristics, dose was the only significant predictor of toxicity. CONCLUSIONS: Published gastrointestinal toxicity reports after hypofractionated radiotherapy for pancreatic cancer were compiled. Median dose was predictive of late grade ≥ 3 gastrointestinal toxicity. Preliminary NTCP parameters were derived for multiple volume constraints.

The effectiveness of bivalving, cast spreading, and webril cutting to reduce cast pressure in a fiberglass short arm cast.

BACKGROUND: A fiberglass short arm cast can be used to treat a distal radial fracture, but posttraumatic edema may lead to excessive cast tightness and resultant soft-tissue injury. We sought to quantify a simulated edema-induced pressure within a fiberglass short arm cast and to determine the effectiveness of different cast-cutting methods for pressure reduction. We hypothesized that cast cutting could eliminate all clinically relevant pressure and Ace wrap would insignificantly increase pressure. METHODS: Skin surface pressure under fiberglass short arm casts was measured on ninety wrists from forty-five volunteers randomly assigned to one cast-cutting method: single-cut (cast bivalve and Ace wrap), double-cut (cast bivalve, spread, and Ace wrap), or triple-cut (cast bivalve, spread, Webril cut, and Ace wrap). Each wrist was immobilized in a cast in the neutral position with one roll of 2-inch (5.1-cm) cotton Webril and one roll of 2-inch (5.1-cm) fiberglass. Each fiberglass short arm cast contained an empty intravenous fluid bag in which we infused air. This simulated edema, which generated a skin surface pressure, which was measured by a pressure transducer. RESULTS: Each cast-cutting method significantly reduced (p < 0.0001) the skin surface pressure from the average maximum of 92.5 mm Hg in a non-fracture setting. Prior to Ace wrapping, there was a reduction in skin surface pressure of 70.8% for the single-cut method, 85.1% for the double-cut method, and 99.9% for the triple-cut method. Ace wrap significantly increased skin surface pressure (p < 0.0001), lessening the effectiveness of cast cutting. There was an overall reduction in skin surface pressure of 55.9% for the single-cut method, 64.3% for the double-cut method, and 77.2% for the triple-cut method. Throughout our study, women had significantly higher skin surface pressure than men (p < 0.0001); the average maximum was 104.4 mm Hg for women and 81.1 mm Hg for men. CONCLUSIONS: The single-cut method provides the greatest pressure reduction, but only the triple-cut method eliminated all relevant skin surface pressure. Ace wrapping a cut cast noticeably increased skin surface pressure. CLINICAL RELEVANCE: In volunteers without a fracture, only the triple-cut method is effective enough to eliminate clinically relevant skin surface pressure. Ace wrap should be applied with caution after the cast is cut. The specific effect on pressure reduction in a patient who requires some soft-tissue pressure to maintain fracture reduction was not studied.

Anomalous muscles within the first dorsal extensor compartment of the wrist.

A 73-year-old woman presented with a 12-month history of a tender first dorsal extensor compartment of her right wrist along with swelling which extended proximally. Caring for her grandchildren exacerbated her pain, and rest relieved it. Over a 2-month period, two injections and splint immobilization failed to provide pain relief and swelling reduction. An ultrasound showed anomalous muscles within the first dorsal extensor compartment. Surgical release of the first compartment showed the abductor pollicis longus and extensor pollicis brevis tendons flanked by muscles within an inflamed sheath. Releasing the compartment resulted in complete pain relief. Anatomic variations within the first dorsal extensor compartment have been reported, but there has been no report on double anomalous muscles within the compartment. The details of the case, utility of ultrasound, and a brief review of the literature are described.

PTEN deficiency mediates a reciprocal response to IGFI and mTOR inhibition.

UNLABELLED: Recent evidence implicates the insulin-like growth factor (IGF) pathway in development of Ewing sarcoma, a highly malignant bone and soft-tissue tumor that primarily affects children and young adults. Despite promising results from preclinical studies of therapies that target this pathway, early-phase clinical trials have shown that a significant fraction of patients do not benefit, suggesting that cellular factors determine tumor sensitivity. Using FAIRE-seq, a chromosomal deletion of the PTEN locus in a Ewing sarcoma cell line was identified. In primary tumors, PTEN deficiency was observed in a large subset of cases, although not mediated by large chromosomal deletions. PTEN loss resulted in hyperactivation of the AKT signaling pathway. PTEN rescue led to decreased proliferation, inhibition of colony formation, and increased apoptosis. Strikingly, PTEN loss decreased sensitivity to IGF1R inhibitors but increased responsiveness to temsirolimus, a potent mTOR inhibitor, as marked by induction of autophagy. These results suggest that PTEN is lost in a significant fraction of primary tumors, and this deficiency may have therapeutic consequences by concurrently attenuating responsiveness to IGF1R inhibition while increasing activity of mTOR inhibitors. The identification of PTEN status in the tumors of patients with recurrent disease could help guide the selection of therapies. IMPLICATIONS: PTEN status in Ewing sarcoma affects cellular responses to IGFI and mTOR-directed therapy, thus justifying its consideration as a biomarker in future clinical trials.

EWS and RE1-Silencing Transcription Factor Inhibit Neuronal Phenotype Development and Oncogenic Transformation in Ewing Sarcoma.

The gene encoding EWS (EWSR1) is involved in various chromosomal translocations that cause the production of oncoproteins responsible for multiple cancers including Ewing sarcoma, myxoid liposarcoma, soft tissue clear cell sarcoma, and desmoplastic small round cell sarcoma. It is well known that EWS fuses to FLI to create EWS/FLI, which is the abnormal transcription factor that drives tumor development in Ewing sarcoma. However, the role of wild-type EWS in Ewing sarcoma pathogenesis remains unclear. In the current study, we identified EWS-regulated genes and cellular processes through RNA interference combined with RNA sequencing and functional annotation analyses. Interestingly, we found that EWS and EWS/FLI co-regulate a significant cluster of genes, indicating an interplay between the 2 proteins in regulating cellular functions. We found that among the EWS-down-regulated genes are a subset of neuronal genes that contain binding sites for the RE1-silencing transcription factor (REST or neuron-restrictive silencer factor [NRSF]), neuron-restrictive silencer element (NRSE), suggesting a cooperative interaction between REST and EWS in gene regulation. Co-immunoprecipitation analysis demonstrated that EWS interacts directly with REST. Genome-wide binding analysis showed that EWS binds chromatin at or near NRSE. Furthermore, functional studies revealed that both EWS and REST inhibit neuronal phenotype development and oncogenic transformation in Ewing sarcoma cells. Our data implicate an important role of EWS in the development of Ewing sarcoma phenotype and highlight a potential value in modulating EWS function in the treatment of Ewing sarcoma and other EWS translocation-based cancers.

Tumor-specific retargeting of an oncogenic transcription factor chimera results in dysregulation of chromatin and transcription.

Chromosomal translocations involving transcription factor genes have been identified in an increasingly wide range of cancers. Some translocations can create a protein "chimera" that is composed of parts from different proteins. How such chimeras cause cancer, and why they cause cancer in some cell types but not others, is not understood. One such chimera is EWS-FLI, the most frequently occurring translocation in Ewing Sarcoma, a malignant bone and soft tissue tumor of children and young adults. Using EWS-FLI and its parental transcription factor, FLI1, we created a unique experimental system to address questions regarding the genomic mechanisms by which chimeric transcription factors cause cancer. We found that in tumor cells, EWS-FLI targets regions of the genome distinct from FLI1, despite identical DNA-binding domains. In primary endothelial cells, however, EWS-FLI and FLI1 demonstrate similar targeting. To understand this mistargeting, we examined chromatin organization. Regions targeted by EWS-FLI are normally repressed and nucleosomal in primary endothelial cells. In tumor cells, however, bound regions are nucleosome depleted and harbor the chromatin signature of enhancers. We next demonstrated that through chimerism, EWS-FLI acquired the ability to alter chromatin. Expression of EWS-FLI results in nucleosome depletion at targeted sites, whereas silencing of EWS-FLI in tumor cells restored nucleosome occupancy. Thus, the EWS-FLI chimera acquired chromatin-altering activity, leading to mistargeting, chromatin disruption, and ultimately, transcriptional dysregulation.

Aberrant estrogen regulation of PEMT results in choline deficiency-associated liver dysfunction.

When dietary choline is restricted, most men and postmenopausal women develop multiorgan dysfunction marked by hepatic steatosis (choline deficiency syndrome (CDS)). However, a significant subset of premenopausal women is protected from CDS. Because hepatic PEMT (phosphatidylethanolamine N-methyltransferase) catalyzes de novo biosynthesis of choline and this gene is under estrogenic control, we hypothesized that there are SNPs in PEMT that disrupt the hormonal regulation of PEMT and thereby put women at risk for CDS. In this study, we performed transcript-specific gene expression analysis, which revealed that estrogen regulates PEMT in an isoform-specific fashion. Locus-wide SNP analysis identified a risk-associated haplotype that was selectively associated with loss of hormonal activation. Chromatin immunoprecipitation, analyzed by locus-wide microarray studies, comprehensively identified regions of estrogen receptor binding in PEMT. The polymorphism (rs12325817) most highly linked with the development of CDS (p < 0.00006) was located within 1 kb of the critical estrogen response element. The risk allele failed to bind either the estrogen receptor or the pioneer factor FOXA1. These data demonstrate that allele-specific ablation of estrogen receptor-DNA interaction in the PEMT locus prevents hormone-inducible PEMT expression, conferring risk of CDS in women.

Improved ChIP-chip analysis by a mixture model approach.

BACKGROUND: Microarray analysis of immunoprecipitated chromatin (ChIP-chip) has evolved from a novel technique to a standard approach for the systematic study of protein-DNA interactions. In ChIP-chip, sites of protein-DNA interactions are identified by signals from the hybridization of selected DNA to tiled oligomers and are graphically represented as peaks. Most existing methods were designed for the identification of relatively sparse peaks, in the presence of replicates. RESULTS: We propose a data normalization method and a statistical method for peak identification from ChIP-chip data based on a mixture model approach. In contrast to many existing methods, including methods that also employ mixture model approaches, our method is more flexible by imposing less restrictive assumptions and allowing a relatively large proportion of peak regions. In addition, our method does not require experimental replicates and is computationally efficient. We compared the performance of our method with several representative existing methods on three datasets, including a spike-in dataset. These comparisons demonstrate that our approach is more robust and has comparable or higher power than the other methods, especially in the context of abundant peak regions. CONCLUSION: Our data normalization and peak detection methods have improved performance to detect peak regions in ChIP-chip data.

The Drosophila gap gene giant has an anterior segment identity function mediated through disconnected and teashirt.

The C2H2 zinc-finger-containing transcription factors encoded by the disconnected (disco) and teashirt (tsh) genes contribute to the regionalization of the Drosophila embryo by establishing fields in which specific Homeotic complex (Hom-C) proteins can function. In Drosophila embryos, disco and the paralogous disco-related (disco-r) are expressed throughout most of the epidermis of the head segments, but only in small patches in the trunk segments. Conversely, tsh is expressed extensively in the trunk segments, with little or no accumulation in the head segments. Little is known about the regulation of these genes; for example, what limits their expression to these domains? Here, we report the regulatory effects of gap genes on the spatial expression of disco, disco-r, and tsh during Drosophila embryogenesis. The data shed new light on how mutations in giant (gt) affect patterning within the anterior gt domain, demonstrating homeotic function in this domain. However, the homeosis does not occur through altered expression of the Hom-C genes but through changes in the regulation of disco and tsh.

The appendage role of insect disco genes and possible implications on the evolution of the maggot larval form.

Though initially identified as necessary for neural migration, Disconnected and its partially redundant paralog, Disco-related, are required for proper head segment identity during Drosophila embryogenesis. Here, we present evidence that these genes are also required for proper ventral appendage development during development of the adult fly, where they specify medial to distal appendage development. Cells lacking the disco genes cannot contribute to the medial and distal portions of ventral appendages. Further, ectopic disco transforms dorsal appendages toward ventral fates; in wing discs, the medial and distal leg development pathways are activated. Interestingly, this appendage role is conserved in the red flour beetle, Tribolium (where legs develop during embryogenesis), yet in the beetle we found no evidence for a head segmentation role. The lack of an embryonic head specification role in Tribolium could be interpreted as a loss of the head segmentation function in Tribolium or gain of this function during evolution of flies. However, we suggest an alternative explanation. We propose that the disco genes always function as appendage factors, but their appendage nature is masked during Drosophila embryogenesis due to the reduction of limb fields in the maggot style Drosophila larva.