The Regenstrief Medical Record System: a quarter century experience

Entrusted with the records for more than 1.5 million patients, the Regenstrief Medical Record System (RMRS) has evolved into a fast and comprehensive data repository used extensively at three hospitals on the Indiana University Medical Center campus and more than 30 Indianapolis clinics. The RMRS routinely captures laboratory results, narrative reports, orders, medications, radiology reports, registration information, nursing assessments, vital signs, EKGs and other clinical data. In this paper, we describe the RMRS data model, file structures and architecture, as well as recent necessary changes to these as we coordinate a collaborative effort among all major Indianapolis hospital systems, improving patient care by capturing city-wide laboratory and encounter data. We believe that our success represents persistent efforts to build interfaces directly to multiple independent instruments and other data collection systems, using medical standards such as HL7, LOINC, and DICOM. Inpatient and outpatient order entry systems, instruments for visit notes and on-line questionnaires that replace hardcopy forms, and intelligent use of coded data entry supplement the RMRS. Physicians happily enter orders, problems, allergies, visit notes, and discharge summaries into our locally developed Gopher order entry system, as we provide them with convenient output forms, choice lists, defaults, templates, reminders, drug interaction information, charge information, and on-line articles and textbooks. To prepare for the future, we have begun wrapping our system in Web browser technology, testing voice dictation and understanding, and employing wireless technology.

Electrophilic prostaglandins and lipid aldehydes repress redox-sensitive transcription factors p53 and hypoxia-inducible factor by impairing the selenoprotein thioredoxin reductase

Tumor suppressor p53 exhibits an enigmatic phenotype in cells exposed to electrophilic, cyclopentenone prostaglandins of the A and J series. Namely, cells harboring a wild-type p53 gene accumulate p53 protein that is conformationally and functionally impaired. This occurs via an unknown molecular mechanism. We report that electrophilic cyclopentenone prostaglandins covalently modify and inhibit thioredoxin reductase, a selenoprotein that governs p53 and other redox-sensitive transcription factors. This mechanism accounts fully for the unusual p53 phenotype in cells exposed to electrophilic prostaglandins. Based on this mechanism we derived, tested, and affirmed several predictions regarding the kinetics of p53 inactivation; the protective effects of selenium; the structure-activity relationships for inhibition of thioredoxin reductase and impairment of p53 by electrophilic lipids; the susceptibility of hypoxia-inducible factor to inactivation by electrophilic lipids; and the equivalence of chemical inactivation of p53 to deletion of a p53 allele. Chemical precepts dictate that other electrophilic agents should also inhibit thioredoxin reductase and impair its governance of redox-sensitive proteins. Our results provide a novel framework to understand how endogenous and exogenous electrophiles might participate in carcinogenesis; how selenoproteins and selenium might confer protection against cancer; how certain tumors might acquire their paradoxical p53 phenotype; and how chronic inflammation might heighten the risk for cancer.

Melanocortin 1 receptor genotype: an important determinant of the damage response of melanocytes to ultraviolet radiation

The melanocortin 1 receptor gene is a main determinant of human pigmentation, and a melanoma susceptibility gene, because its variants that are strongly associated with red hair color increase melanoma risk. To test experimentally the association between melanocortin 1 receptor genotype and melanoma susceptibility, we compared the responses of primary human melanocyte cultures naturally expressing different melanocortin 1 receptor variants to α-melanocortin and ultraviolet radiation. We found that expression of 2 red hair variants abolished the response to α-melanocortin and its photoprotective effects, evidenced by lack of functional coupling of the receptor, and absence of reduction in ultraviolet radiation-induced hydrogen peroxide generation or enhancement of repair of DNA photoproducts, respectively. These variants had different heterozygous effects on receptor function. Microarray data confirmed the observed differences in responses of melanocytes with functional vs. nonfunctional receptor to α-melanocortin and ultraviolet radiation, and identified DNA repair and antioxidant genes that are modulated by α-melanocortin. Our findings highlight the molecular mechanisms by which the melanocortin 1 receptor genotype controls genomic stability of and the mutagenic effect of ultraviolet radiation on human melanocytes.

Evaluation of a 7-Day Continuous Intravenous Infusion of Decitabine: Inhibition of Promoter-Specific and Global Genomic DNA Methylation

Purpose

The nucleoside analog 5-aza-2′-deoxycytidine (5-aza-CdR, decitabine) is a potent inhibitor of DNA methylation in vitro. Cellular treatment with this agent induces the re-expression of methylation-silenced genes. It remains unclear to what extent this compound inhibits DNA methylation in vivo. A clinical study was designed to examine the molecular effects and toxicity of a continuous 1-week intravenous infusion of decitabine in solid tumor patients.

Methods

Ten patients with refractory solid tumors were included in this study. Decitabine was administered at 2 mg/m2/d via continuous infusion for 168 hours. Quantitative polymerase chain reaction and high performance liquid chromatography were utilized to measure promoter-specific and global DNA methylation in peripheral-blood cells before and after treatment.

Results

Transient grade III/IV neutropenia (two patients) and grade II thrombocytopenia (one patient) was observed at the lowest planned dose step (2 mg/m2/d for 7 days). Nonhematologic toxicities were not observed. Quantitative polymerase chain reaction demonstrated significant MAGE-1 promoter hypomethylation by 14 days after the start of treatment in all 13 treatment cycles examined. Significant genomic DNA hypomethylation was also seen by day 14 in 11 of 13 treatment cycles analyzed. Genomic DNA methylation reverted to baseline levels by 28 to 35 days after the start of treatment, demonstrating that inhibition of DNA methylation by decitabine is transient.

Conclusion

A 168-hour continuous infusion of decitabine is well tolerated and results in the inhibition of promoter-specific and genomic DNA methylation in vivo. This treatment schedule is suitable for evaluation of decitabine in combination with agents whose activity may be enhanced by the reversal of DNA methylation–mediated gene silencing.

The p16(INK4A) tumor suppressor regulates cellular oxidative stress

Mutations or deletions in the cyclin-dependent kinase inhibitor p16(INK4A) are associated with multiple cancer types, but are more commonly found in melanoma tumors and associated with familial melanoma predisposition. Although p16 is thought to function as a tumor suppressor by negatively regulating the cell cycle, it remains unclear why the genetic compromise of p16 predisposes to melanoma over other cancers. Here we describe a novel role for p16 in regulating oxidative stress in several cell types, including melanocytes. Expression of p16 was rapidly upregulated following ultraviolet-irradiation and in response to H₂O₂-induced oxidative stress in a p38 stress-activated protein kinase-dependent manner. Knockdown of p16 using small interfering RNA increased intracellular reactive oxygen species (ROS) and oxidative (8-oxoguanine) DNA damage, which was further enhanced by H₂O₂ treatment. Elevated ROS levels were also observed in p16-depleted human keratinocytes and in whole skin and dermal fibroblasts from Cdkn2a-deficient mice. Aberrant ROS and p38 signaling in Cdkn2a-deficient fibroblasts was normalized by expression of exogenous p16. The effect of p16 depletion on ROS was not recapitulated by the knockdown of retinoblastoma protein (Rb) and did not require Rb. Finally, p16-mediated suppression of ROS could not be attributed to the potential effects of p16 on cell cycle phase. These findings suggest a potential alternate Rb-independent tumor-suppressor function of p16 as an endogenous regulator of carcinogenic intracellular oxidative stress. Compared with keratinocytes and fibroblasts, we also found increased susceptibility of melanocytes to oxidative stress in the context of p16 depletion, which may explain why the compromise of p16 predisposes to melanoma over other cancers.

Identification, genetic testing, and management of hereditary melanoma

Several distinct melanoma syndromes have been defined, and genetic tests are available for the associated causative genes. Guidelines for melanoma genetic testing have been published as an informal "rule of twos and threes," but these guidelines apply to CDKN2A testing and are not intended for the more recently described non-CDKN2A melanoma syndromes. In order to develop an approach for the full spectrum of hereditary melanoma patients, we have separated melanoma syndromes into two types: "melanoma dominant" and "melanoma subordinate." Syndromes in which melanoma is a predominant cancer type are considered melanoma dominant, although other cancers, such as mesothelioma or pancreatic cancers, may also be observed. These syndromes are associated with defects in CDKN2A, CDK4, BAP1, MITF, and POT1. Melanoma-subordinate syndromes have an increased but lower risk of melanoma than that of other cancer(s) seen in the syndrome, such as breast and ovarian cancer or Cowden syndrome. Many of these melanoma-subordinate syndromes are associated with well-established predisposition genes (e.g., BRCA1/2, PTEN). It is likely that these predisposition genes are responsible for the increased susceptibility to melanoma as well but with lower penetrance than that observed for the dominant cancer(s) in those syndromes. In this review, we describe our extension of the "rule of twos and threes" for melanoma genetic testing. This algorithm incorporates an understanding of the spectrum of cancers and genes seen in association with melanoma to create a more comprehensive and tailored approach to genetic testing.

Skin cancer screening: recommendations for data-driven screening guidelines and a review of the US Preventive Services Task Force controversy

Melanoma is usually apparent on the skin and readily detected by trained medical providers using a routine total body skin examination, yet this malignancy is responsible for the majority of skin cancer-related deaths. Currently, there is no national consensus on skin cancer screening in the USA, but dermatologists and primary care providers are routinely confronted with making the decision about when to recommend total body skin examinations and at what interval. The objectives of this paper are: to propose rational, risk-based, data-driven guidelines commensurate with the US Preventive Services Task Force screening guidelines for other disorders; to compare our proposed guidelines to recommendations made by other national and international organizations; and to review the US Preventive Services Task Force's 2016 Draft Recommendation Statement on skin cancer screening.

Thioredoxin reductase is required for the inactivation of tumor suppressor p53 and for apoptosis induced by endogenous electrophiles

Previous studies demonstrate that the covalent modification of thioredoxin reductase (TrxR) by both endogenous and exogenous electrophiles results in disruption of the conformation of the tumor suppressor protein p53. Here we report that the loss of normal cellular TrxR enzymatic activity by electrophilic modification or deletion of the C-terminal catalytic selenocysteine residue has functional consequences that are distinct from those resulting from depletion of TrxR protein in human RKO colon cancer cells. A thorough kinetic analysis was performed on purified TrxR in order to characterize the mechanism of its inhibition by electrophiles. Furthermore, electrospray mass spectrometry confirmed the alkylation of TrxR by lipid electrophiles and liquid chromatography-mass spectrometry/mass spectrometry identified the C-terminus as one target for alkylation. Then the consequences of TrxR modification by electrophiles on p53 conformation, transactivation and apoptosis were compared and contrasted with the effects of depletion of TrxR protein by treatment of cells with small interfering RNA directed against TrxR1. We found that cells depleted of TrxR were actually less sensitive to electrophile-induced disruption of p53 conformation and apoptosis than were cells expressing normal levels of TrxR. When RKO cells depleted of wild-type TrxR were transfected with C-terminal mutants of TrxR lacking the catalytic selenocysteine, p53 was found to be conformationally deranged, similar to cells treated with electrophiles. These results lead us to conclude that C-terminal modification of TrxR is both necessary and sufficient for the disruption of p53 and for the induction of apoptosis. Endogenous lipid electrophiles have been our primary focus; however, metabolic activation of hormones can generate endogenous mutagens, and we demonstrate that estrone-quinone attenuates p53 function in human MCF7 cells.

Studies on the binding of staphylococcal 125I-labeled alpha-toxin to rabbit erythrocytes

Staphylococcal alpha-toxin, a hemolytic exotoxin, can be iodinated using the lactoperoxidase method. 125 I-Labeled alpha-toxin binds to rabbit erythrocytes in an apparently irreversible and highly specific manner. The binding of 125 I-labeled alpha-toxin to erythrocytes of rabbit and human reflects the species specificity of native alpha-toxin. Binding of 125I-labeled alpha-toxin is blocked by the presence of native alpha-toxin, 127I-labeled alpha-toxin, or anti-alpha-toxin antibody. Simultaneous assays of 125I-labeled alpha-toxin binding and leakage of intracellular 86Rb+ suggest that toxin binding and membrane damage are separate, sequential functions. Both the rate and extent of binding are temperature dependent. Rabbit erythrocytes possess 5 X 10(3) binding sites/cell, while human erythrocytes possess no detectable binding sites. Treatment of rabbit erythrocytes with 125I-labeled alpha-toxin appears to decrease the number of unoccupied binding sites. Chaotropic ions can inhibit 125I-labeled alpha-toxin binding and cause bound 125I-labeled alpha-toxin to dissociate from rabbit erythrocyte membranes. Treatment of intact rabbit erythrocytes with pronase reduces both the binding capacity of the cells for 125I-labeled alpha-toxin, and the cells' sensitivity to hemolysis by native alpha-toxin. It is proposed that the primary binding site for alpha-toxin in biomembranes is a surface membrane protein.

N-acetylcysteine protects melanocytes against oxidative stress/damage and delays onset of ultraviolet-induced melanoma in mice

PURPOSE

UV radiation is the major environmental risk factor for melanoma and a potent inducer of oxidative stress, which is implicated in the pathogenesis of several malignancies. We evaluated whether the thiol antioxidant N-acetylcysteine (NAC) could protect melanocytes from UV-induced oxidative stress/damage in vitro and from UV-induced melanoma in vivo.

EXPERIMENTAL DESIGN

In vitro experiments used the mouse melanocyte line melan-a. For in vivo experiments, mice transgenic for hepatocyte growth factor and survivin, shown previously to develop melanoma following a single neonatal dose of UV irradiation, were given NAC (7 mg/mL; mother's drinking water) transplacentally and through nursing until 2 weeks after birth.

RESULTS

NAC (1-10 mmol/L) protected melan-a cells from several UV-induced oxidative sequelae, including production of intracellular peroxide, formation of the signature oxidative DNA lesion 8-oxoguanine, and depletion of free reduced thiols (primarily glutathione). Delivery of NAC reduced thiol depletion and blocked formation of 8-oxoguanine in mouse skin following neonatal UV treatment. Mean onset of UV-induced melanocytic tumors was significantly delayed in NAC-treated compared with control mice (21 versus 14 weeks; P = 0.0003).

CONCLUSIONS

Our data highlight the potential importance of oxidative stress in the pathogenesis of melanoma and suggest that NAC may be useful as a chemopreventive agent.

Evaluation of Biodistribution of Sulforaphane after Administration of Oral Broccoli Sprout Extract in Melanoma Patients with Multiple Atypical Nevi

Broccoli sprout extract containing sulforaphane (BSE-SFN) has been shown to inhibit ultraviolet radiation-induced damage and tumor progression in skin. This study evaluated the toxicity and potential effects of oral BSE-SFN at three dosages. Seventeen patients who each had at least 2 atypical nevi and a prior history of melanoma were randomly allocated to 50, 100, or 200 μmol oral BSE-SFN daily for 28 days. Atypical nevi were photographed on days 1 and 28, and plasma and nevus samples were taken on days 1, 2, and 28. Endpoints assessed were safety, plasma and skin sulforaphane levels, gross and histologic changes, IHC for phospho-STAT3(Y705), Ki-67, Bcl-2, HMOX1, and TUNEL, plasma cytokine levels, and tissue proteomics. All 17 patients completed 28 days with no dose-limiting toxicities. Plasma sulforaphane levels pooled for days 1, 2, and 28 showed median postadministration increases of 120 ng/mL for 50 μmol, 206 ng/mL for 100 μmol, and 655 ng/mL for 200 μmol. Median skin sulforaphane levels on day 28 were 0.0, 3.1, and 34.1 ng/g for 50, 100, and 200 μmol, respectively. Plasma levels of proinflammatory cytokines decreased from day 1 to 28. The tumor suppressor decorin was increased from day 1 to 28. Oral BSE-SFN is well tolerated at daily doses up to 200 μmol and achieves dose-dependent levels in plasma and skin. A larger efficacy evaluation of 200 μmol daily for longer intervals is now reasonable to better characterize clinical and biological effects of BSE-SFN as chemoprevention for melanoma. Cancer Prev Res; 11(7); 429-38. ©2018 AACR.

Responses of human cells to ZnO nanoparticles: a gene transcription study

The gene transcript profile responses to metal oxide nanoparticles was studied using human cell lines derived from the colon and skin tumors. Much of the research on nanoparticle toxicology has focused on models of inhalation and intact skin exposure, and effects of ingestion exposure and application to diseased skin are relatively unknown. Powders of nominally nanosized SiO2, TiO2, ZnO and Fe2O3 were chosen because these substances are widely used in consumer products. The four oxides were evaluated using colon-derived cell lines, RKO and CaCo-2, and ZnO and TiO2 were evaluated further using skin-derived cell lines HaCaT and SK Mel-28. ZnO induced the most notable gene transcription changes, even though this material was applied at the lowest concentration. Nano-sized and conventional ZnO induced similar responses suggesting common mechanisms of action. The results showed neither a non-specific response pattern common to all substances nor synergy of the particles with TNF-α cotreatment. The response to ZnO was not consistent with a pronounced proinflammatory signature, but involved changes in metal metabolism, chaperonin proteins, and protein folding genes. This response was observed in all cell lines when ZnO was in contact with the human cells. When the cells were exposed to soluble Zn, the genes involved in metal metabolism were induced but the genes involved in protein refoldling were unaffected. This provides some of the first data on the effects of commercial metal oxide nanoparticles on human colon-derived and skin-derived cells.

The State of Melanoma: Emergent Challenges and Opportunities

Five years ago, the Melanoma Research Foundation (MRF) conducted an assessment of the challenges and opportunities facing the melanoma research community and patients with melanoma. Since then, remarkable progress has been made on both the basic and clinical research fronts. However, the incidence, recurrence, and death rates for melanoma remain unacceptably high and significant challenges remain. Hence, the MRF Scientific Advisory Council and Breakthrough Consortium, a group that includes clinicians and scientists, reconvened to facilitate intensive discussions on thematic areas essential to melanoma researchers and patients alike, prevention, detection, diagnosis, metastatic dormancy and progression, response and resistance to targeted and immune-based therapy, and the clinical consequences of COVID-19 for patients with melanoma and providers. These extensive discussions helped to crystalize our understanding of the challenges and opportunities facing the broader melanoma community today. In this report, we discuss the progress made since the last MRF assessment, comment on what remains to be overcome, and offer recommendations for the best path forward.

Inhibition of Ca2+-activated tension and myosin light chain phosphorylation in skinned smooth muscle strips by the phenothiazines

The antipsychotic phenothiazine drugs trifluoperazine, chlorpromazine, and promethazine inhibited Ca2+-activated tension in functionally skinned rabbit ileum and rabbit pulmonary artery strips. Exogenous calmodulin rapidly reversed the inhibition of tension. Inhibition of the endogenous myosin light chain kinase by these drugs resulted with ATP or its analog. ATP gamma S, as a substrate. The evidence presented suggests the inhibition of Ca2+ activation of tension in skinned smooth muscle preparations by phenothiazines is due to the inhibition of Ca2+-activated phosphorylation of the 20,000 dalton myosin light chain by the endogenous myosin light chain kinase.

A study of inter-arm blood pressure differences in primary care

OBJECTIVES

To investigate whether there are inter-arm blood pressure differences that are of clinical importance to general practice.

DESIGN AND SETTING

Pragmatic study with randomised order of use of left or right arm carried out in routine surgeries in an inner city and suburban general practice.

SUBJECTS

There were 237 patients presenting opportunistically for blood pressure measurement to a nurse or general practitioner.

MAIN OUTCOME MEASURES

95% limits of agreement between measurements on the left and right arm and bias between arms.

RESULTS

Large inter-arm blood pressure differences exist reflected in wide 95% limits of agreement; -16 mm Hg to 24 mm Hg for the right minus the left arm diastolic blood pressure. There is a small but statistically significant bias to the right arm blood pressure measuring higher than the left (3.7 mm Hg diastolic, 2.4 to 5 mm Hg 95% confidence intervals). An interarm difference of 10 mm Hg or greater for diastolic blood pressure occurred in 40% of subjects and a difference of 20 mm Hg or more for systolic blood pressure occurred in 23% of subjects.

CONCLUSIONS

In a primary care setting blood pressure should be measured routinely in both arms. If one arm is to be preferred for pragmatic clinical purposes, then this should be the right arm.

Evaluation of Ixekizumab Treatment for Patients With Pityriasis Rubra Pilaris: A Single-Arm Trial

Importance

Pityriasis rubra pilaris is a rare and disabling cutaneous disease that is frequently recalcitrant to conventional therapies and appears to involve interleukin (IL)-17 overexpression.

Objective

To investigate the clinical response and safety of ixekizumab in treating pityriasis rubra pilaris.

Design, Setting, and Participants

Single-arm, investigator-initiated trial conducted in adult patients with moderate to severe pityriasis rubra pilaris at a single-center academic university from June 2018 to January 2020. A total of 41 patients were screened, 12 were enrolled, and 11 completed the full duration of therapy. A referred, consecutive sample was used during participant selection. The treatment period and primary outcome occurred over 24 weeks with additional patient follow-up through 36 weeks.

Intervention

Subcutaneous administration of ixekizumab, a humanized IgG4 antibody that binds IL-17A, at the US Food and Drug Administration-approved dosing schedule for treatment of psoriasis for 24 weeks.

Main Outcomes and Measures

The primary outcome was the mean change in Psoriasis Area and Severity Index at 24 weeks. Secondary outcomes included change in affected body surface area, quality of life, induction of sustained remission, and association of improvement with CARD14 genetic variations and cutaneous cytokine expression.

Results

A total of 12 white patients (mean [SD] age, 49.8 [15.1] years; 8 male [67%]) were enrolled between June 2018 and April 2019, with 11 completing the full course of intervention. The mean (SEM) improvements in Psoriasis Area and Severity Index, affected body surface area, and Dermatology Life Quality Index were 15.2 (2.1) (P < .0001), 29.8% (9.3%) (P = .009), and 9.5 (2.5) (P = .004), respectively. The 4 participants with the most improvement in Psoriasis Area and Severity Index at week 24 stayed in remission at week 36 (defined as lack of increase in Psoriasis Area and Severity Index from week 24 through week 36), off therapy. Relative dermal IL-17A expression decreased by a 1.9 log-fold change. No participants had known pathogenic CARD14 variations. There were no serious adverse events.

Conclusions and Relevance

In this single-armed trial, ixekizumab was associated with reduced clinical signs and symptoms of pityriasis rubra pilaris in a subset of patients, including those in whom other systemic therapies have failed.

Trial Registration

ClinicalTrials.gov Identifier: NCT03485976.

Atrial fibrillation: a risk factor for increased mortality--an AVID registry analysis

Emerging evidence suggests that atrial fibrillation is not a benign arrhythmia. It is associated with increased risk of death. The magnitude of association is controversial and potential causes remain unknown. Patients in the registry of the Antiarrhythmics Versus Implantable Defibrillators (AVID) Trial form the basis for this report. Baseline variables, in particular the presence or absence of a history of atrial fibrillation/flutter, were examined in relation to survival. Multivariate Cox regression was used to adjust for differences in important baseline co-variables using 27 pre-selected variables. There were 3762 subjects who were followed for an average of 773+/-420 days; 1459 (39 %) qualified with ventricular fibrillation and 2303 (61 %) with ventricular tachycardia. A history of atrial fibrillation/flutter was present in 24.4 percent. There were many differences in baseline variables between those with and those without a history of atrial fibrillation/flutter. After adjustment for baseline differences, a history of atrial fibrillation/flutter remained a significant independent predictor of mortality, (relative risk=1.20; 95 % confidence intervals=1.03-1.40; p=0.020). Antiarrhythmic drug use, other than amiodarone or sotalol, was also a significant independent predictor of mortality (relative risk 1.34; 95 % confidence intervals 1.07-1.69, p=0.011. Atrial fibrillation/flutter is a significant independent risk factor for increased mortality in patients presenting with ventricular tachyarrhythmias. This risk may have been overestimated in previous studies that could not adjust for the proarrhythmic effects of antiarrhythmic drugs other than amiodarone or sotalol.

Yeast protein farnesyltransferase: steady-state kinetic studies of substrate binding

Protein farnesyltransferase (PFTase) catalyzes the alkylation of cysteine in C-terminal CaaX sequences of a variety of proteins, including Ras, nuclear lamins, large G-proteins, and phosphodiesterases, by farnesyl diphosphate (FPP). These modifications enhance the ability of the proteins to associate with membranes and are essential for their respective functions. The binding mechanism for yeast PFTase was deduced from a combination of steady-state kinetic and equilibrium studies. Rates for prenylation were measured by a continuous assay based on an enhancement in the fluorescence of the dansyl moiety in pentapeptide dansyl-GCVIA upon farnesylation by FPP. Unreactive substrate analogs for FPP and dansyl-GCVIA gave steady-state inhibition patterns for the dead-end inhibitors typical of an ordered sequential mechanism in which FPP adds to the enzyme before the peptide. The kinetic analysis was complicated by substrate inhibition for dansyl-GCVIA. The substrate inhibition was reversed at high concentrations of FPP, indicating that formation of the nonproductive enzyme--peptide complex is competitive with respect to FPP. Progress curves were fitted to an integrated form of the rate expression to determine the catalytic constant, kcat = 4.5 +/- 1.9 s-1, and the Michaelis constant for dansyl-GCVIA, KMD = 0.9 +/- 0.1 microM. The dissociation constant for FPP, KD = 75 +/- 15 nM, was measured using a membrane retention assay.

Protein purification: adsorption chromatography on controlled pore glass with the use of chaotropic buffers

Chromatography on controlled pore glass in combination with chaotropic buffers makes possible, in a single step, protein purifications of several hundredfold. The new emphasis is on highly selective controllable adsorption. The method is useful for the purification and concentration of proteins from large volumes of complex media and for the purification of proteins that are poorly soluble or tend to aggregate in aqueous solution D-(-)-Beta-Hydroxybutyrate dehydrogenase, a mitochondrial membrane-bound protein, several soluble proteins, and staphylococcal alpha toxin, which can be purified directly from large volumes of culture medium, are used to illustrate the method.

Purification of staphylococcal alpha-toxin by adsorption chromatography on glass

Staphylococcal alpha-toxin was purified from Staphylococcus aureus growth medium using adsorption chromatography on controlled pore glass beads. Elution of alpha-toxin from the unmodified glass surface of the beads with various anions generally followed the chaotropic series. Alpha-toxin, purified by glass bead chromatography, is composed of a single electrophoretic form, containing less than 2% of other forms.

Use of oral N-acetylcysteine for protection of melanocytic nevi against UV-induced oxidative stress: towards a novel paradigm for melanoma chemoprevention

PURPOSE

Induction of oxidative stress has been implicated in UV-induced melanoma. We sought to determine whether the antioxidant N-acetylcysteine (NAC) could be safely administered to protect melanocytic nevi from the oxidative stress resulting from acute UV exposure.

EXPERIMENTAL DESIGN

Patients at increased risk for melanoma were recruited from a screening clinic. Induction and detection of oxidative stress (reactive oxygen species and glutathione depletion) was optimized in nevi following ex vivo UV irradiation. Nevi were removed from patients before, and following, oral ingestion of a single (1,200 mg) dose of NAC, and then these nevi were UV irradiated (4,000 J/m(2)).

RESULTS

Oxidative stress was induced in nevi 24 to 48 hours following ex vivo UV irradiation. A single oral dose of NAC was well tolerated in all patients (n = 72). Basal levels of reduced glutathione and the NAC metabolite cysteine were well correlated between similar-appearing nevi from the same patient and were significantly increased in nevi removed 3 hours after NAC ingestion compared with nevi removed before drug ingestion. In approximately half (9 of 19) of patients tested, UV-induced glutathione depletion was attenuated in the postdrug (compared with predrug) nevus.

CONCLUSIONS

NAC can be safely administered to patients for the purpose of modulating UV-induced oxidative stress in nevi. This study suggests the feasibility of patients taking NAC prophylactically before acute UV exposure, to prevent pro-oncogenic oxidative stress in nevi and ultimately reduce long-term melanoma risk.

Novel approaches in melanoma prevention and therapy

The incidence of cutaneous melanoma has risen at a rate significantly higher than that for other malignancies. This increase persists despite efforts to educate the public about the dangers of excess exposure to UV radiation from both the sun and tanning beds. Melanoma affects a relatively younger population and is notorious for its propensity to metastasize and for its poor response to current therapeutic regimens. These factors make prevention an integral component to the goal of decreasing melanoma-related mortality. Transformation of melanocytes into malignant melanoma involves the interplay between genetic factors, UV exposure, and the tumor microenvironment. The roles of UV radiation in the etiology of melanoma are mediated by both direct damage of DNA through formation of photoproducts and production of reactive oxygen species (ROS). Many of the promising antioxidant agents under development for the prevention of melanoma are derived from foodstuffs. B-Raf is a member of the Raf kinase family of serine/threonine-specific protein kinases that plays a role in regulating the MAP kinase/ERKs signaling pathway. About 50 % of melanomas harbor activating BRAF mutations. BRAF mutations are found in 59 % of the melanomas arising in skin with intermittent sun exposure, such as trunk and arms, as compared with only 23 % of the acral melanomas, 11 % of mucosal melanomas, and 0 % of uveal melanomas. Two new agents, ipilimumab and vemurafenib, have been shown to improve outcome of advanced melanoma as presented at the plenary session of the 2011 annual meeting of the American Society of Clinical Oncology. Vemurafenib is the first personalized compound which demonstrated an improvement in progression-free survival (PFS) and overall survival (OS) in metastatic melanoma harboring the BRAFV600 mutation and represents the first drug of a class that exerts its anti-proliferative activity through inhibition of a highly specific molecular target. GSK2118436 (dabrafenib), the second BRAF inhibitor, in phase I and II trial obtained similar results to vemurafenib. A phase III trial is now ongoing. Taken together, the early clinical development of vemurafenib and dabrafenib clearly confirms that BRAF inhibitors can halt or reverse disease in patients with melanomas carrying this mutation, improving survival times compared with historically standard treatments (chemotherapy and interleukin-2). The clinical development of other new BRAF inhibitors such as RAF265 and LGX818 is now ongoing. Combination strategies of BRAF inhibitors with ipilimumab, an anti-CTLA-4 antibody, and/or MEK inhibitors or metformin are now under investigation in clinical trials.

Selenium for the prevention of cutaneous melanoma

The role of selenium (Se) supplementation in cancer prevention is controversial; effects often depend on the nutritional status of the subject and on the chemical form in which Se is provided. We used a combination of in vitro and in vivo models to study two unique therapeutic windows for intervention in the process of cutaneous melanomagenisis, and to examine the utility of two different chemical forms of Se for prevention and treatment of melanoma. We studied the effects of Se in vitro on UV-induced oxidative stress in melanocytes, and on apoptosis and cell cycle progression in melanoma cells. In vivo, we used the HGF transgenic mouse model of UV-induced melanoma to demonstrate that topical treatment with l-selenomethionine results in a significant delay in the time required for UV-induced melanoma development, but also increases the rate of growth of those tumors once they appear. In a second mouse model, we found that oral administration of high dose methylseleninic acid significantly decreases the size of human melanoma xenografts. Our findings suggest that modestly elevation of selenium levels in the skin might risk acceleration of growth of incipient tumors. Additionally, certain Se compounds administered at very high doses could have utility for the treatment of fully-malignant tumors or prevention of recurrence.