Bivalirudin for the treatment of patients with confirmed or suspected heparin-induced thrombocytopenia

BACKGROUND

Heparin-induced thrombocytopenia (HIT) is an adverse immune-mediated response to unfractionated heparin and, less commonly, low molecular weight heparin. It is associated with a high thrombotic risk and the potential for limb and life-threatening complications. Argatroban is the only approved and currently available anticoagulant for HIT treatment in the USA.

OBJECTIVES

To report safety and efficacy outcomes with bivalirudin for HIT treatment.

METHODS

We retrospectively examined records from our registry of patients with a suspected, confirmed or previous history of HIT and who had received bivalirudin for anticoagulation in a single tertiary-care center over a 9-year period.

RESULTS

We identified 461 patients who received bivalirudin: 220 (47.7%) were surgical patients, and 241 (52.3%) were medical patients. Of this population, 107 (23.2%) were critically ill, and 109 (23.6%) were dialysis-dependent. Suspected, confirmed and previous history of HIT were reported in 262, 124 and 75 patients, respectively. Of 386 patients with suspected or confirmed HIT, 223 patients (57.8%) had thrombosis at HIT diagnosis. New thrombosis was identified in 21 patients (4.6%) while they were on treatment with therapeutic doses of bivalirudin. No patient required HIT-related amputation. Major bleeding occurred in 35 patients (7.6%). We found a significant increase in major bleeding risk in the critically ill population (13.1%; odds ratio 2.4, 95% confidence interval 1.2-4.9, P = 0.014). The 30-day all-cause mortality rate was 14.5% (67 patients), and eight of 67 (1.7%) deaths were HIT-related.

CONCLUSION

Bivalirudin may be an effective and safe alternative option for the treatment of both suspected and confirmed HIT, and appears to reduce the rate of HIT-related amputation.

LIM proteins in actin cytoskeleton mechanoresponse

The actin cytoskeleton assembles into branched networks or bundles to generate mechanical force for critical cellular processes such as establishment of polarity, adhesion, and migration. Stress fibers (SFs) are contractile actomyosin structures that physically couple to the extracellular matrix through integrin-based focal adhesions (FAs), thereby transmitting force into and across the cell. Recently, LIN-11, Isl1, and MEC-3 (LIM) domain proteins have been implicated in mediating this cytoskeletal mechanotransduction. Among the more well-studied LIM domain adapter proteins is zyxin, a dynamic component of both FAs and SFs. Here we discuss recent research detailing the mechanisms by which SFs adjust their structure and composition to balance mechanical forces and suggest ways that zyxin and other LIM domain proteins mediate mechanoresponse.

High-power beam transport through a hollow-core photonic bandgap fiber

We investigate the use of a seven-cell hollow-core photonic bandgap fiber for transport of CW laser radiation from a single-mode, narrow-linewidth, high-power fiber laser amplifier. Over 90% of the amplifier output was coupled successfully and transmitted through the fiber in a near-Gaussian mode, with negligible backreflection into the source. 100 W of power was successfully transmitted continuously without damage and 160 W of power was transmitted briefly before the onset of thermal lensing in the coupling optics.

Review of the clinical and biologic aspects of human papillomavirus-positive squamous cell carcinomas of the head and neck

Human papillomavirus (HPV), a known etiology of a subset of head-and-neck squamous cell carcinomas (HNCs), causes numerous alterations in normal cellular functions. This article reviews the biology, detection, and treatment of HPV-positive HNC. The role of HPV oncoproteins in tumor development, the natural history of HPV infection, and risk factors for and prevention of transmission of oral HPV are considered. Commonly used methods for detecting HPV infection, including limitations of these methods, are discussed to aid the practicing clinician in using these tests in their clinical practice. Clinical characteristics of HPV-positive HNC, including potential explanations for the improved outcomes seen in patients with HPV-positive HNC, are assessed. Ongoing clinical trials specific for patients with HPV-positive HNC are described, and areas in need of additional research are summarized. Until the results of ongoing trials are known, treatment of HPV-positive HNC should not differ in clinical practice from treatment of similar non-HPV related cancers.

Colon Cancer Staging in Vulnerable Older Adults: Adherence to National Guidelines and Impact on Survival

BACKGROUND

There is concern that elders are not adequately evaluated prior to colon cancer surgery. We sought to determine adherence with ACOVE-3 (Assessing Care of Vulnerable Elders) quality indicators for pre-operative staging prior to colectomy for colon cancer utilizing the Surveillance, Epidemiology and End Results (SEER)-Medicare linked database (1992-2005).

METHODS

We determined the proportion of patients aged 75 and older who had preoperative staging prior to colectomy for colon adenocarcinoma. Preoperative staging was defined as abdominopelvic computed tomography or magnetic resonance imaging scan (SCAN) and colonoscopy or flexible sigmoidoscopy (SCOPE). Multivariate logistic regression identified predictors of adherence. Odds ratios were adjusted for comorbidity, socioeconomic status, and disease severity. The association of adherence to ACOVE-3 and survival was quantified.

RESULTS

Of the 37,862 patients, the majority were 75-84 years, 28% of the patients were ≥85 years. Regarding preoperative staging in the 6-month interval prior to surgical resection, 8% had neither SCAN nor SCOPE, 6% had only SCAN, 43% had only SCOPE, and 43% had both SCAN and SCOPE. Compared to patients who were not staged, those evaluated with either SCOPE alone or SCAN plus SCOPE had lower odds of 3-year mortality. Patients who were staged with SCAN alone had an increased odds of death compared to those who had neither SCAN or SCOPE.

CONCLUSIONS

These data demonstrate that the majority of vulnerable elders with colon cancer did not receive appropriate preoperative staging prior to resection. The findings also confirm that adherence to ACOVE-3 guidelines is associated with improved long-term survival.

Functional analysis of serially expanded human iPS cell-derived RPE cultures

PURPOSE

To determine the effects of serial expansion on the cellular, molecular, and functional properties of human iPS cell (hiPSC)-derived RPE cultures.

METHODS

Fibroblasts obtained from four individuals were reprogrammed into hiPSCs and differentiated to RPE cells using previously described methods. Patches of deeply pigmented hiPSC-RPE were dissected, dissociated, and grown in culture until they re-formed pigmented monolayers. Subsequent passages were obtained by repeated dissociation, expansion, and maturation of RPE into pigmented monolayers. Gene and protein expression profiles and morphological and functional characteristics of hiPSC-RPE at different passages were compared with each other and to human fetal RPE (hfRPE).

RESULTS

RPE from all four hiPSC lines could be expanded more than 1000-fold when serially passaged as pigmented monolayer cultures. Importantly, expansion of hiPSC-RPE monolayers over the first three passages (P1-P3) resulted in decreased expression of pluripotency and neuroretinal markers and maintenance of characteristic morphological features and gene and protein expression profiles. Furthermore, P1 to P3 hiPSC-RPE monolayers reliably demonstrated functional tight junctions, G-protein-coupled receptor-mediated calcium transients, phagocytosis and degradation of photoreceptor outer segments, and polarized secretion of biomolecules. In contrast, P4 hiPSC-RPE cells failed to form monolayers and possessed altered morphological and functional characteristics and gene expression levels.

CONCLUSIONS

Highly differentiated, pigmented hiPSC-RPE monolayers can undergo limited serial expansion while retaining key cytological and functional attributes. However, passaging hiPSC-RPE cultures beyond senescence leads to loss of such features. Our findings support limited, controlled passaging of patient-specific hiPSC-RPE to procure cells needed for in vitro disease modeling, drug screening, and cellular transplantation.

Synergistic activities of a silver(I) glutamic acid complex and reactive oxygen species (ROS): a novel antimicrobial and chemotherapeutic agent

The antimicrobial and chemotherapeutic activities of a silver(I) glutamic acid complex with the synergistic concomitant generation of reactive oxygen species (ROS) were investigated here. The ROS generation system employed was via Fenton chemistry. The antimicrobial and chemotherapeutic activities were investigated on Staphylococcus aureus ATCC 43300 and Escherichia coli bacteria, and Vero and MCF-7 tumor cell lines, respectively. Antimicrobial activities were conducted by determining minimum inhibitory concentration (MIC), while chemotherapeutic efficacies were done by serial dilution using standard techniques to determine the half maximal inhibitory concentration (IC50). The antimicrobial and chemotherapeutic results obtained were compared with positive control drugs gentamicin, oxacillin, penicillin, streptomycin and cisplatin, a ubiquitously used platinum-based antitumor drug, and with the silver(I) glutamic acid complex and hydrogen peroxide separately. Based on MIC and IC50 values, it was determined that this synergistic approach was very effective at extremely low concentrations, especially when compared with the other drugs evaluated here. This finding might be of great significance regarding metronomic dosing when this synergistic approach is clinically implemented. Since silver at low concentrations exhibits no toxic, mutagenic and carcinogenic activities, this might offer an alternative approach for the development of safer silver-based antimicrobial and chemotherapeutic drugs, thereby reducing or even eliminating the toxicity associated with current drugs. Accordingly, the present approach might be integrated into the systemic clinical treatment of infectious diseases and cancer.

Mechanism of allopurinol induced TPMT inhibition

Up to 1/5 of patients with wildtype thiopurine-S-methyltransferase (TPMT) activity prescribed azathioprine (AZA) or mercaptopurine (MP) demonstrate a skewed drug metabolism in which MP is preferentially methylated to yield methylmercaptopurine (MeMP). This is known as thiopurine hypermethylation and is associated with drug toxicity and treatment non-response. Co-prescription of allopurinol with low dose AZA/MP (25-33%) circumvents this phenotype and leads to a dramatic reduction in methylated metabolites; however, the biochemical mechanism remains unclear. Using intact and lysate red cell models we propose a novel pathway of allopurinol mediated TPMT inhibition, through the production of thioxanthine (TX, 2-hydroxymercaptopurine). In red blood cells pre-incubated with 250 μM MP for 2h prior to the addition of 250 μM TX or an equivalent volume of Earle's balanced salt solution, there was a significant reduction in the concentration of MeMP detected at 4h and 6h in cells exposed to TX (4 h, 1.68, p=0.0005, t-test). TX acts as a direct TPMT inhibitor with an apparent Ki of 0.329 mM. In addition we have confirmed that the mechanism is relevant to in vivo metabolism by demonstrating raised urinary TX levels in patients receiving combination therapy. We conclude that the formation of TX in patients receiving combination therapy with AZA/MP and allopurinol, likely explains the significant reduction of methylated metabolites due to direct TPMT inhibition.

Enhanced radiation sensitivity in HPV-positive head and neck cancer

Patients with human papillomavirus (HPV+)-associated head and neck cancer (HNC) show significantly improved survival outcome compared with those with HPV-negative (HPV-) tumors. Published data examining this difference offers conflicting results to date. We systematically investigated the radiation sensitivity of all available validated HPV+ HNC cell lines and a series of HPV- HNC cell lines using in vitro and in vivo techniques. HPV+ HNCs exhibited greater intrinsic radiation sensitivity (average SF2 HPV-: 0.59 vs. HPV+: 0.22; P < 0.0001), corresponding with a prolonged G2-M cell-cycle arrest and increased apoptosis following radiation exposure (percent change 0% vs. 85%; P = 0.002). A genome-wide microarray was used to compare gene expression 24 hours following radiation between HPV+ and HPV- cell lines. Multiple genes in TP53 pathway were upregulated in HPV+ cells (Z score 4.90), including a 4.6-fold increase in TP53 (P < 0.0001). Using immortalized human tonsillar epithelial (HTE) cells, increased radiation sensitivity was seen in cell expressing HPV-16 E6 despite the effect of E6 to degrade p53. This suggested that low levels of normally functioning p53 in HPV+ HNC cells could be activated by radiation, leading to cell death. Consistent with this, more complete knockdown of TP53 by siRNA resulted in radiation resistance. These results provide clear evidence, and a supporting mechanism, for increased radiation sensitivity in HPV+ HNC relative to HPV- HNC. This issue is under active investigation in a series of clinical trials attempting to de-escalate radiation (and chemotherapy) in selected patients with HPV+ HNC in light of their favorable overall survival outcome.

Neurofilaments are the major neuronal target of hydroxynonenal-mediated protein cross-links

Lipid peroxidation generates reactive aldehydes, most notably hydroxynonenal (HNE), which covalently binds amino acid residue side chains leading to protein inactivation and insolubility. Specific adducts of lipid peroxidation have been demonstrated to be intimately associated with pathological lesions of Alzheimer's disease (AD), suggesting that oxidative stress is a major component in the disease. Here, we examined the HNE-cross-linking modifications by using an antibody specific for a lysine-lysine cross-link. Since in a prior study we noted no immunolabeling of neuritic plaques or neurofibrillary tangles but instead found strong labeling of axons, we focused this study on axons. Axonal labeling was examined in mouse sciatic nerve, and immunoblotting showed the cross-link was restricted to neurofilament heavy and medium subunits, which while altering migration, did not indicate larger NF aggregates, indicative of intermolecular cross-links. Examination of mice at various ages showed the extent of modification remaining relatively constant through the life span. These findings demonstrate lipid-cross-linking peroxidation primarily involves lysine-rich neurofilaments and is restricted to intramolecular cross-links.

Abstract 5474: Epidermal growth factor inhibition of HPV positive head and neck cancer cells and primary tumorgrafts results in significant growth inhibition mediated by apoptosis

Purpose: Cetuximab, a monoclonal antibody targeting the epidermal growth factor receptor (EGFR), is approved for use in the treatment of head and neck cancer (HNC). One recent study (SPECTRUM) suggested that patient with recurrent or metastatic HPV+ HNC do not benefit from treatment with EGFR targeted therapy. However, most studies of EGFR inhibition have been performed with HPV-negative cells and clinical trials have been performed without regard to HPV status. We performed this study to determine whether HPV+ HNC cells and patient-derived tumorgrafts respond to cetuximab and to examine the mechanisms through which cetuximab affects HPV+ HNC.

Methods: Four HPV+ cell lines (UD-SCC2, UM-SCC47, UPCI-SCC90, 93-VU-147T) were assessed for EGFR expression by western blot. Sensitivity to cetuximab was tested by assessing cell density 2, 4, 6, and 8 days after cetuximab treatment and by assessing colony formation 2 weeks after plating. Apoptosis was measured by caspase activation, flow cytometry for Annexin V and propidium iodide staining, and immunoblot. Cell cycle was assessed by immunoblot for cyclin D1, cyclin B1, and p27Kip-1 and confirmed by flow cytometry for propidium iodide stained cells. Subcutaneous flank xenografts and tumorgrafts were performed in Hsd:athymic Nude-Foxn1nu female mice treated with intraperitoneal cetuximab (0.2mg/mouse) delivered twice weekly for 2 weeks. Time to tumor quadrupling from baseline was assessed by Kaplan-Meier method.

Results: Significant variation in EGFR expression was seen in HPV+ cells. Cetuximab treatment resulted in significant delay in cell proliferation (p&lt;0.005 for all lines) and decrease in colony formation (p&lt;0.04 for all lines). In these cell lines, cetuximab caused an increase in apoptosis as measured by caspase activity, Bax activation, and Annexin V labeling. In addition, as previously seen in HPV- cell lines, cetuximab increased p27Kip-1 and decreased cyclin B1 and cyclin D1 coinciding with in a G1 cell cycle arrest. Using both a cell line xenograft model and a direct-from-patient tumorgraft model of HPV+ HNCs, cetuximab resulted in significant tumor growth delay (median time to tumor quadrupling: 15 vs. 24 days, p=0.02; and 42 vs. 89 days, p=0.0001, respectively).

Conclusions: Epidermal growth factor receptor inhibition by cetuximab appears to be effective in slowing proliferation and inducing apoptosis in HPV+ HNC. The proposed mechanism of action appears to be similar to that shown over a decade ago in HPV- HNC. These results suggest that cetuximab may play a role in the management of patients with HPV+ HNC.

Citation Format: Grace C. Blitzer, Molly A. Smith, Alexandra D. Torres, Eric A. Armstrong, Paul M. Harari, Paul F. Lambert, Randall J. Kimple. Epidermal growth factor inhibition of HPV positive head and neck cancer cells and primary tumorgrafts results in significant growth inhibition mediated by apoptosis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5474. doi:10.1158/1538-7445.AM2013-5474

Abstract 73: Preclinical evaluation of chemoradiation with cetuximab HPV-positive head and neck cancer suggests significant radiosensitization

PURPOSE: Whether cetuximab, a monoclonal antibody to the epidermal growth factor receptor, should be combined with radiation in patients with human papillomavirus (HPV) positive locally advanced head and neck cancer (HNC) is not known. Currently available data are inadequate to address this important therapeutic question. We sought to examine the ability of cetuximab to act as a radiosensitizer and to examine the mechanism of action of this combination in a model system of HPV+ HNC.

METHODS: Four cell lines (UD-SCC2, UM-SCC47, UPCI-SCC90, 93-VU-147T) validated for HPV expression were used for all assays. Subcutaneous flank xenografts were performed in Hsd:athymic Nude-Foxn1nu female mice treated with intraperitoneal cetuximab (0.2mg/mouse) or flank radiation (2 Gy/fraction) delivered twice weekly for 2 weeks. Time to tumor quadrupling from baseline was assessed by Kaplan-Meier method. Flow cytometry was used to assess apoptosis by Annexin V staining and cell cycle distribution by propidium iodide staining.

RESULTS: While there was minimal in vitro radiosensitization after treatment with cetuximab (similar to that seen in HPV-negative HNC), cetuximab + radiation resulted in a significant increase in time to tumor quadrupling compared to cetuximab alone (p=0.001) or radiation alone (p&lt;0.0001) in HPV+ HNC xenografts. Increased apoptosis was seen in cetuximab and radiation treated cells. Analysis of cell cycle distribution 24 hours after drug treatment showed that cetuximab induced a modest G1 cell cycle arrest when given prior to radiation, but that 24 hours after combined therapy, a significant G2 arrest was present.

CONCLUSIONS: Using HPV+ HNC cell lines, radiation and cetuximab appear to be beneficial compared to either treatment alone. This combination, currently undergoing study in randomized clinical trial is being further evaluated in a direct from patient tumorgraft model of HPV+ HNC to further understand predictors of response.

Citation Format: Molly A. Smith, Grace C. Blitzer, Alexandra D. Torres, Eric A. Armstrong, Paul F. Lambert, Paul M. Harari, Randall J. Kimple. Preclinical evaluation of chemoradiation with cetuximab HPV-positive head and neck cancer suggests significant radiosensitization. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 73. doi:10.1158/1538-7445.AM2013-73

B vitamins and cognitive performance in older adults: review

A copious amount of scientific scrutiny has been dedicated to documenting typical and atypical human ageing, with a substantial body of work focusing upon the impact of lifestyle choices. One such lifestyle choice is that of diet and, in particular, micronutrient ingestion. Epidemiological studies have reported positive associations between B vitamin status and cognitive function, including negative associations between biological markers (i.e., homocysteine) of dysregulated one-carbon metabolism and cognitive function. This has led to a surge of randomised control trials (RCTs) investigations into B vitamin therapy. However, results have continuingly failed to show beneficial behavioural effects. Despite this, results reliably show treatment-related increases in B vitamin level and decreases in homocysteine level—both of which have been identified as risk factors for atypical ageing. In this paper we argue that it would be premature to conclude that B vitamin therapy has no potential and that more research is needed to systematically investigate the optimal dose, the therapeutic “window,” and individual differences in therapy responders and nonresponders. We start with a brief look at one-carbon metabolism and then consider the evidence from epidemiological studies and RCTs in relation to three specific B vitamins: folic acid (B9), pyridoxine (B6), and cobamides (B12).

Two methods for modelling the propagation of terahertz radiation in a layered structure

Modelling the interaction of terahertz(THz) radiation with biological tissueposes many interesting problems. THzradiation is neither obviously described byan electric field distribution or anensemble of photons and biological tissueis an inhomogeneous medium with anelectronic permittivity that is bothspatially and frequency dependent making ita complex system to model.A three-layer system of parallel-sidedslabs has been used as the system throughwhich the passage of THz radiation has beensimulated. Two modelling approaches havebeen developed a thin film matrix model anda Monte Carlo model. The source data foreach of these methods, taken at the sametime as the data recorded to experimentallyverify them, was a THz spectrum that hadpassed though air only.Experimental verification of these twomodels was carried out using athree-layered in vitro phantom. Simulatedtransmission spectrum data was compared toexperimental transmission spectrum datafirst to determine and then to compare theaccuracy of the two methods. Goodagreement was found, with typical resultshaving a correlation coefficient of 0.90for the thin film matrix model and 0.78 forthe Monte Carlo model over the full THzspectrum. Further work is underway toimprove the models above 1 THz.

Catalogue of human tissue optical properties at terahertz frequencies

Recently published studies suggest thatterahertz pulsed imaging will have applications inmedicine and biology, but there iscurrently very little information about the opticalproperties of human tissue at terahertzfrequencies. Such information would be useful forpredicting the feasibility of proposedapplications, optimising acquisition protocols,providing information about variability ofhealthy tissue and supplying data for studies of theinteraction mechanisms. Research ethicscommittee approval was obtained, andmeasurements made from samples of freshlyexcised human tissue, using a broadbandterahertz pulsed imaging system comprisingfrequencies approximately 0.5 to 2.5 THz.Refractive index and linear absorptioncoefficient were found. Reproducibility wasdetermined using blood from one volunteer,which was drawn and measured on consecutivedays. Skin, adipose tissue, striatedmuscle, vein and nerve were measured (to date, from oneindividual). Water had a higher refractiveindex (2.04 ± 0.07) than any tissue.The linear absorption coefficient was higher formuscle than adipose tissue, as expectedfrom the higher hydration of muscle. As these samples camefrom a single subject, there is currentlyinsufficient statistical power to draw firmconclusions, but results suggest that in vivo clinical imaging will be feasible in certainapplications.

The mu/kappa agonist nalbuphine attenuates sensitization to the behavioral effects of cocaine

Sensitization refers to an increase in sensitivity to a drug and is believed to play a role in the etiology of substance use disorders. The purpose of the present study was to evaluate the ability of the mixed mu/kappa agonist nalbuphine to modulate sensitization to the locomotor and positive reinforcing effects of cocaine. Rats were habituated to a locomotor activity chamber and treated with saline (1.0 ml/kg, ip), cocaine (10 mg/kg, ip), or cocaine+nalbuphine (10 mg/kg, ip) every day for 10 days. Following locomotor activity testing, rats were implanted with intravenous catheters and cocaine self-administration was examined on fixed ratio (FR) and progressive ratio (PR) schedules of reinforcement. Rats treated with cocaine exhibited a progressive increase in locomotor activity over the 10-day treatment period, and this effect was significantly reduced in rats treated with cocaine+nalbuphine. In self-administration tests, rats treated with cocaine exhibited significantly higher levels of responding at a threshold dose of cocaine (0.03 mg/kg/infusion) on both FR and PR schedules than rats treated with saline. This increase in responding at a threshold dose of cocaine was blocked completely in rats treated with cocaine+nalbuphine. These data suggest that nalbuphine attenuates the development of sensitization to the behavioral effects of cocaine.

Development and characterization of HPV-positive and HPV-negative head and neck squamous cell carcinoma tumorgrafts

PURPOSE

To develop a clinically relevant model system to study head and neck squamous cell carcinoma (HNSCC), we have established and characterized a direct-from-patient tumorgraft model of human papillomavirus (HPV)-positive and HPV-negative cancers.

EXPERIMENTAL DESIGN

Patients with newly diagnosed or recurrent HNSCC were consented for donation of tumor specimens. Surgically obtained tissue was implanted subcutaneously into immunodeficient mice. During subsequent passages, both formalin-fixed/paraffin-embedded as well as flash-frozen tissues were harvested. Tumors were analyzed for a variety of relevant tumor markers. Tumor growth rates and response to radiation, cisplatin, or cetuximab were assessed and early passage cell strains were developed for rapid testing of drug sensitivity.

RESULTS

Tumorgrafts have been established in 22 of 26 patients to date. Significant diversity in tumorgraft tumor differentiation was observed with good agreement in degree of differentiation between patient tumor and tumorgraft (Kappa 0.72). Six tumorgrafts were HPV-positive on the basis of p16 staining. A strong inverse correlation between tumorgraft p16 and p53 or Rb was identified (Spearman correlations P = 0.085 and P = 0.002, respectively). Significant growth inhibition of representative tumorgrafts was shown with cisplatin, cetuximab, or radiation treatment delivered over a two-week period. Early passage cell strains showed high consistency in response to cancer therapy between tumorgraft and cell strain.

CONCLUSIONS

We have established a robust human tumorgraft model system for investigating HPV-positive and HPV-negative HNSCC. These tumorgrafts show strong correlation with the original tumor specimens and provide a powerful resource for investigating mechanisms of therapeutic response as well as preclinical testing.

iPS cell modeling of Best disease: insights into the pathophysiology of an inherited macular degeneration

Best disease (BD) is an inherited degenerative disease of the human macula that results in progressive and irreversible central vision loss. It is caused by mutations in the retinal pigment epithelium (RPE) gene BESTROPHIN1 (BEST1), which, through mechanism(s) that remain unclear, lead to the accumulation of subretinal fluid and autofluorescent waste products from shed photoreceptor outer segments (POSs). We employed human iPS cell (hiPSC) technology to generate RPE from BD patients and unaffected siblings in order to examine the cellular and molecular processes underlying this disease. Consistent with the clinical phenotype of BD, RPE from mutant hiPSCs displayed disrupted fluid flux and increased accrual of autofluorescent material after long-term POS feeding when compared with hiPSC-RPE from unaffected siblings. On a molecular level, RHODOPSIN degradation after POS feeding was delayed in BD hiPSC-RPE relative to unaffected sibling hiPSC-RPE, directly implicating impaired POS handling in the pathophysiology of the disease. In addition, stimulated calcium responses differed between BD and normal sibling hiPSC-RPE, as did oxidative stress levels after chronic POS feeding. Subcellular localization, fractionation and co-immunoprecipitation experiments in hiPSC-RPE and human prenatal RPE further linked BEST1 to the regulation and release of endoplasmic reticulum calcium stores. Since calcium signaling and oxidative stress are critical regulators of fluid flow and protein degradation, these findings likely contribute to the clinical picture of BD. In a larger context, this report demonstrates the potential to use patient-specific hiPSCs to model and study maculopathies, an important class of blinding disorders in humans.

Cocaine-induced cardiotoxicity in vitro

A growing number of reports have related cocaine use with the onset of myocardial infarction in young otherwise healthy individuals. Although the cardiac effects of cocaine have traditionally been attributed to sympathomimetic stimulation, several studies have suggested that cocaine may be directly cardiotoxic. The purpose of this study was to evaluate the cardiotoxic effects of cocaine in an in vitro preparation devoid of sympathetic innervation. Primary cultures of rat cardiac muscle and non-muscle cells were prepared from hearts excised from 3-5-day-old Sprague-Dawley rats. Cultures were exposed to various cocaine concentrations (1 x 10(-7)-1 x 10(-3)m) for 1-24 hr. Beating activity, morphological status and lactate dehydrogenase (LDH) leakage were evaluated following cocaine exposure. A decrease in the beating activity of cultured muscle cells was observed 1 hr after exposure to the highest cocaine concentrations (1 x 10(-5)-1 x 10(-3)m) tested. Similar results were obtained 24 hr after exposure. Morphological alterations in muscle cells were evident only after exposure to the highest concentration (1 x 10(-3)m). Vacuoles appeared 1 hr after cocaine exposure and were replaced by dark granules within 24 hr. LDH release was significantly elevated in the muscle cell cultures exposed to 1 x 10(-3)m cocaine for 24 hr. The pattern of cocaine-induced morphological alterations and enzyme leakage was similar in non-muscle cells. These data suggest that cocaine induces direct toxic effects on both cardiac muscle and non-muscle cells maintained in an environment free of neuronal and hormonal influences.

Formation of amino acids and nucleotide bases in a Titan atmosphere simulation experiment

The discovery of large (>100 u) molecules in Titan's upper atmosphere has heightened astrobiological interest in this unique satellite. In particular, complex organic aerosols produced in atmospheres containing C, N, O, and H, like that of Titan, could be a source of prebiotic molecules. In this work, aerosols produced in a Titan atmosphere simulation experiment with enhanced CO (N(2)/CH(4)/CO gas mixtures of 96.2%/2.0%/1.8% and 93.2%/5.0%/1.8%) were found to contain 18 molecules with molecular formulae that correspond to biological amino acids and nucleotide bases. Very high-resolution mass spectrometry of isotopically labeled samples confirmed that C(4)H(5)N(3)O, C(4)H(4)N(2)O(2), C(5)H(6)N(2)O(2), C(5)H(5)N(5), and C(6)H(9)N(3)O(2) are produced by chemistry in the simulation chamber. Gas chromatography-mass spectrometry (GC-MS) analyses of the non-isotopic samples confirmed the presence of cytosine (C(4)H(5)N(3)O), uracil (C(5)H(4)N(2)O(2)), thymine (C(5)H(6)N(2)O(2)), guanine (C(5)H(5)N(5)O), glycine (C(2)H(5)NO(2)), and alanine (C(3)H(7)NO(2)). Adenine (C(5)H(5)N(5)) was detected by GC-MS in isotopically labeled samples. The remaining prebiotic molecules were detected in unlabeled samples only and may have been affected by contamination in the chamber. These results demonstrate that prebiotic molecules can be formed by the high-energy chemistry similar to that which occurs in planetary upper atmospheres and therefore identifies a new source of prebiotic material, potentially increasing the range of planets where life could begin.

Preclinical pharmacology of AZD2327: a highly selective agonist of the δ-opioid receptor

In the present article, we summarize the preclinical pharmacology of 4-{(R)-(3-aminophenyl)[4-(4-fluorobenzyl)-piperazin-1-yl]methyl}-N,N-diethylbenzamide (AZD2327), a highly potent and selective agonist of the δ-opioid receptor. AZD2327 binds with sub-nanomolar affinity to the human opioid receptor (K(i) = 0.49 and 0.75 nM at the C27 and F27 isoforms, respectively) and is highly selective (>1000-fold) over the human μ- and κ-opioid receptor subtypes as well as >130 other receptors and channels. In functional assays, AZD2327 shows full agonism at human δ-opioid receptors ([(35)S]GTPγ EC(50) = 24 and 9.2 nM at C27 and F27 isoforms, respectively) and also at the rat and mouse δ-opioid receptors. AZD2327 is active in a wide range of models predictive of anxiolytic activity, including a modified Geller-Seifter conflict test and social interaction test, as well as in antidepressant models, including learned helplessness. In animals implanted with microdialysis probes and then given an acute stressor by pairing electric shock delivery with a flashing light, there is an increase in norepinephrine release into the prefrontal cortex associated with this acute anxiety state. Both the benzodiazepine anxiolytic standard diazepam and AZD2327 blocked this norepinephrine release equally well, and there was no evidence of tolerance to these effects of AZD2327. Overall, these data support the role of the δ-opioid receptor in the regulation of mood, and data suggest that AZD2327 may possess unique antidepressant and anxiolytic activities that could make a novel contribution to the pharmacotherapy of psychiatric disorders.

Formation of NH3 and CH2NH in Titan's upper atmosphere

The large abundance of NH3 in Titan's upper atmosphere is a consequence of coupled ion and neutral chemistry. The density of NH3 is inferred from the measured abundance of NH4+. NH3 is produced primarily through reaction of NH2 with H2CN, a process neglected in previous models. NH2 is produced by several reactions including electron recombination of CH2NH2+. The density of CH2NH2+ is closely linked to the density of CH2NH through proton exchange reactions and recombination. CH2NH is produced by reaction of N(2D) and NH with ambient hydrocarbons. Thus, production of NH3 is the result of a chain of reactions involving non-nitrile functional groups and the large density of NH3 implies large densities for these associated molecules. This suggests that amine and imine functional groups may be incorporated as well in other, more complex organic molecules.