The role of reactive astrocytes in the resistance of melanoma brain metastasis to chemotherapy

Brain metastasis is resistant to chemotherapy while the leaky blood-brain-barrier in brain metastasis can not be the underlying reason. Metastatic tumor cells (“seed”) exploit the host microenvironment (“soil”) for survival advantages. Astrocytes which maintain the homeostasis of the brain microenvironment become reactive subsequent to brain damages and protect neurons from various injuries. We observed reactive astrocytes surrounding and infiltrating into brain metastasis in both clinical specimen and experimental animal model, thus raising a possibility that reactive astrocytes may protect tumor cells from cytotoxic chemotherapeutic drugs. ^ To test this hypothesis, we first generated an immortalized astrocyte cell line from H-2Kb-tsA58 mice. The immortal mouse astrocytes expressed specific markers including GFAP. Scanning electron microscopy demonstrated that astrocytes formed direct physical contact with tumor cells. Moreover, the expression of GFAP by astrocytes was up-regulated subsequent to co-culture with tumor cells, indicating that the co-culture of astrocytes and tumor cells may serve as a model to recapitulate the pathophysiological situation of brain metastasis. ^ In co-culture, astrocytes dramatically reduced apoptosis of tumor cells produced by various chemotherapeutic drugs. This protection effect was not because of culturing cells from different species since mouse fibroblasts did not protect tumor cells from chemotherapy. Furthermore, the protection by astrocytes was completely dependent on a physical contact. ^ Gap junctional communication (GJC) served as this physical contact. Tumor cells and astrocytes both expressed the major component of gap junctional channel—connexin 43 and formed functional GJC as evidenced by the “dye transfer” assay. The blockage of GJC between tumor cells and astrocytes by either specific chemical blocker carbenoxolone (CBX) or by genetically knocking down connexin 43 on astrocytes reversed the chemo-protection. ^ Calcium was the signal molecule transmitted through GJC that rescued tumor cells from chemotherapy. Accumulation of cytoplasmic calcium preceded the progress of apoptosis in tumor cells treated with chemotherapeutic drugs. Furthermore, chelation of accumulated cytoplasmic calcium inhibited the apoptosis of tumor cells treated with chemotherapeutic drugs. Most importantly, astrocytes could “shunt” the accumulated cytoplasmic calcium from tumor cells (treated with chemotherapeutic drug) through GJC. We also used gene expression micro-array to investigate global molecular consequence of tumor cells forming GJC with astrocytes. The data demonstrated that astrocytes (but not fibroblasts), through GJC, up-regulated the expressions of several well known survival genes in tumor cells. ^ In summary, this dissertation provides a novel mechanism underlying the resistance of brain metastasis to chemotherapy, which is due to protection by astrocytes through GJC. Interference with the GJC between astrocytes and tumor cells holds great promise in sensitizing brain metastasis to chemotherapy and improving the prognosis for patients with brain metastasis. ^

Identification of a conserved cluster in the RH domain of GRK critical for activation by GPCRs

One of the most critical aspects of G Protein Coupled Receptors (GPCRs) regulation is their rapid and acute desensitization following agonist stimulation. Phosphorylation of these receptors by GPCR kinases (GRK) is a major mechanism of desensitization. Considerable evidence from studies of rhodopsin kinase and GRK2 suggests there is an allosteric docking site for the receptor distinct from the GRK catalytic site. While the agonist-activated GPCR appears crucial for GRK activation, the molecular details of this interaction remain unclear. Recent studies suggested an important role for the N- and C-termini and domains in the small lobe of the kinase domain in allosteric activation; however, neither the mechanism of action of that site nor the RH domain contributions have been elucidated. To search for the allosteric site, we first indentified evolutionarily conserved sites within the RH and kinase domains presumably deterministic of protein function employing evolutionary trace (ET) methodology and crystal structures of GRK6. Focusing on a conserved cluster centered on helices 3, 9, and 10 in the RH domain, key residues of GRK5 and 6 were targeted for mutagenesis and functional assays. We found that a number of double mutations within helices 3, 9, and 10 and the N-terminus markedly reduced (50–90%) the constitutive phosphorylation of the β-2 Adrenergic Receptor (β2AR) in intact cells and phosphorylation of light-activated rhodopsin (Rho*) in vitro as compared to wild type (WT) GRK5 or 6. Based on these results, we designed peptide mimetics of GRK5 helix 9 both computationally and through chemical modifications with the goal of both confirming the importance of helix 9 and developing a useful inhibitor to disrupt the GPCR-GRK interaction. Several peptides were found to block Rho* phosphorylation by GRK5 including the native helix 9 sequence, Peptide Builder designed-peptide preserving only the key ET residues, and chemically locked helices. Most peptidomimetics showed inhibition of GRK5 activity greater than 80 % with an IC50 of ∼ 30 µM. Alanine scanning of helix 9 has further revealed both essential and non-essential residues for inhibition. Importantly, substitution of Arg 169 by an alanine in the native helix 9-based peptide gave an almost complete inhibition at 30 µM with an IC50 of ∼ 10 µM. In summary we report a previously unrecognized crucial role for the RH domain of GRK5 and 6, and the subsequent identification of a lead peptide inhibitor of protein-protein interaction with potential for specific blockade of GPCR desensitization. ^

Seroprevalence of toxoplasmosis and current thinking regarding screening in pregnancy: A review of the literature and case study discussion

The approach to the diagnosis and treatment of congenital toxoplasmosis has been one of flux and debate, fueled by lack of knowledge, lack of consensus, different methods of screening and different national policies for screening in different parts of the world. Countries with higher prevalence of disease such as in Europe and South America have a heightened awareness of the need to screen and treat for this parasitic infection during pregnancy. In contrast, in the United States, it is a condition scarcely discussed and has been largely ignored except in some large centers and by a few researchers. Policies and research strategies for any condition should start with obtaining good data. The aims of this thesis included a review of prevalence studies conducted in the United States, focused on the past 20 years, combined with a description of original research conducted by the author several years ago. The latter was a cross-sectional study performed in Houston, one of the largest American cities with a great ethnic mix. The study analyzed prevalence rates of Toxoplasma gondii IgG antibody in sera of women of reproductive age. Overall seroprevalence was 12.3%. In keeping with other studies, higher prevalence correlated with lower socioeconomic status, Black and Hispanic and Asian ethnicities, and increasing age. A literature search revealed only three prevalence studies performed in the United States over the past 20 years, with another four studies only referred to as personal communications or within a textbook, without further study detail available. The literature review also revealed a lack of consensus on whether or not to screen for toxoplasmosis in pregnancy, and even whether or not treatment in utero is worthwhile.^ Proponents of screening and treatment in pregnancy site studies both in the United States and France, emphasize that treatment reduces disease manifestations in infants. Opponents cite other studies that show only marginal benefits, together with potential side effects of medication regimens and generation of anxiety in parents. What is agreed on so far is the value of educating pregnant women on how to avoid contracting toxoplasmosis, and educating physicians on making the best use of reference laboratories before major treatment decisions are made. Further research to reevaluate the literature critically, review new treatment regimens and examine costs and benefits of screening and treatment of toxoplasmosis in pregnancy, bringing together European and American researchers, is needed.^

Variance of familial dietary intake

Although many family-based genetic studies have collected dietary data, very few have used the dietary information in published findings. No single solution has been presented or discussed in the literature to deal with the problem of using factor analyses for the analyses of dietary data from several related individuals from a given household. The standard statistical approach of factor analysis cannot be applied to the VIVA LA FAMILIA Study diet data to ascertain dietary patterns since this population consists of three children from each family, thus the dietary patterns of the related children may be correlated and non-independent. Addressing this problem in this project will enable us to describe the dietary patterns in Hispanic families and to explore the relationships between dietary patterns and childhood obesity. ^ In the VIVA LA FAMILIA Study, an overweight child was first identified and then his/her siblings and parents were brought in for data collection which included 24 hour recalls and food frequency questionnaire (FFQ). Dietary intake data were collected using FFQ and 24 hour recalls on 1030 Hispanic children from 319 families. ^ The design of the VIVA LA FAMILIA Study has important and unique statistical considerations since its participants are related to each other, the majority form distinct nuclear families. Thus, the standard approach of factor analysis cannot be applied to these diet data to ascertain dietary patterns. In this project we propose to investigate whether the determinants of the correlation matrix of each family unit will allow us to adjust the original correlation matrix of the dietary intake data prior to ascertaining dietary intake patterns. If these methods are appropriate, then in the future the dietary patterns among related individuals could be assessed by standard orthogonal principal component factor analysis.^

GMZ27 is a new organic arsenic derivative with anti-leukemic activity, via the induction of reactive oxygen species through NADPH oxidase and mitochondrial pathway that lead to leukemia cell apoptosis

Arsenic trioxide (ATO) is an inorganic arsenic derivative that is very effective against relapsed acute promyelocytic leukemia. It is being investigated as therapy for other cancers, but the risk/benefit ratio is questionable due to significant side effects. In contrast, organic arsenic derivatives (OAD) are known to be much less toxic than ATO. Based on high activity, we selected GMZ27 (dipropil-s-glycerol arsenic) for further study and have confirmed its potent activity against human acute leukemia cell lines. This anti-leukemic activity is significantly higher than that of ATO. Both in vivo and in vitro tests have shown that GMZ27 is significantly less toxic to normal bone marrow mononuclear cells and normal mice. Therefore, further study of the biological activity of GMZ27 was undertaken. ^ GMZ27, in contrast to ATO, can only marginally induce maturation of leukemic cells. GMZ27 has no effect on cell cycle. The anti-leukemic activity of GMZ27 against acute myeolocytic leukemia cells is not dependent upon degradation of PML-RARα fusion protein. GMZ27 causes dissipation of mitochondrial transmembrane potential, cleavage of caspase 9, caspase 3 activation. Further studies indicated that GMZ27 induces intracellular reactive oxygen species (ROS) production, and modification of intracellular ROS levels had profound effect on its potential to inhibit proliferation of leukemic cells. Therefore ROS production plays a major role in the anti-leukemic activity of GMZ27. ^ To identify how GMZ27 induces ROS, our studies focused on mitochondria and NADPH oxidase. The results indicated that the source of ROS generation induced by GMZ27 is dose dependent. At the low dose (0.3 uM) GMZ27 induces NADPH oxidase activity that leads to late ROS production, while at the high dose (2.0 uM) mitochondria function is disrupted and early ROS production is induced leading to dramatic cell apoptosis. Therefore, late, ROS production can be detected in mitochondria are depleted Rho-0 cells. Our work not only delineates a major biologic pathway for the anti-leukemic activity of GMZ27, but also discusses possible ways of enhancing the effect by the co-application of NADPH oxidase activator. Further study of this interaction may lead to achieving better therapeutic index.^

The combined effect of pravastatin and aspirin on clinical cardiovascular events

The 3-hydroxy-3methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, or statins, can achieve significant reductions in plasma low-density lipoprotein (LDL)-cholesterol levels. Experimental and clinical evidence now shows that some statins interfere with formation of atherosclerotic lesions independent of their hypolipidemic properties. Vulnerable plaque rupture can result in thrombus formation and artery occlusion; this plaque deterioration is responsible for most acute coronary syndromes, including myocardial infarction (MI), unstable angina, and coronary death, as well as coronary heart diseaseequivalent non-hemorrhagic stroke. Inhibition of HMG-CoA reductase has potential pleiotropic effects other than lipid-lowering, as statins block mevalonic acid production, a precursor to cholesterol and numerous other metabolites. Statins' beneficial effects on clinical events may also thus involve nonlipid-related mechanisms that modify endothelial function, inflammatory responses, plaque stability, and thrombus formation. Aspirin, routinely prescribed to post-MI patients as adjunct therapy, may potentiate statins beneficial effects, as aspirin does not compete metabolically with statins but acts similarly on atherosclerotic lesions. Common functions of both medications include inhibition of platelet activity and aggregation, reduction in atherosclerotic plaque macrophage cell count, and prevention of atherosclerotic vessel endothelial dysfunction. The Cholesterol and Recurrent Events (CARE) trial provides an ideal population in which to examine the combined effects of pravastatin and aspirin. Lipid levels, intermediate outcomes, are examined by pravastatin and aspirin status, and differences between the two pravastatin groups are found. A modified Cox proportional-hazards model with aspirin as a time-dependent covariate was used to determine the effect of aspirin and pravastatin on the clinical cardiovascular composite endpoint of coronary heart disease death, recurrent MI or stroke. Among those assigned to pravastatin, use of aspirin reduced the composite primary endpoint by 35%; this result was similar by gender, race, and diabetic status. Older patients demonstrated a nonsignificant 21% reduction in the primary outcome, whereas the younger had a significant reduction of 43% in the composite primary outcome. Secondary outcomes examined include coronary artery bypass graft (38% reduction), nonsurgical bypass, peripheral vascular disease, and unstable angina. Pravastatin and aspirin in a post-MI population was found to be a beneficial combination that seems to work through lipid and nonlipid, anti-inflammatory mechanisms. ^

Regulation of estrogen receptor alpha by the tumor suppressor p53 in breast cancer cells

Estrogen receptor (ER) and the tumor suppressor p53 are key prognostic indicators in breast cancer. Estrogen signaling through its receptor (ER) controls proliferation of normal as well as transformed mammary epithelial cells, and the presence of ER is established as a marker of good prognosis and response to therapy. The p53 tumor suppressor gene is often referred to as the "cellular gatekeeper" due to its extensive control of cell proliferation and apoptosis. Loss of functional p53 is a negative prognostic indicator and is correlated with lack of response to antiestrogens, reduced disease-free interval and increased chance of disease recurrence. Clinical studies have demonstrated that tumors with mutated p53 tend to be ER negative, while ER positive tumors tend to have wild type p53. ^ Recent studies from our lab indicate that p53 genotype correlates with estrogen receptor expression in mammary tumors in vivo. We therefore hypothesized that p53 regulates ER expression in mammary cancer cells by recruitment of specific cofactors to the ER promoter. To test this, MCF-7 cells were treated with doxorubicin or ionizing radiation, both of which stimulated significant increases in p53 expression, as expected, but also increased ER expression in a p53-dependent manner. Furthermore, in cells treated with siRNA targeting p53, both p53 and ER protein levels were significantly reduced. P53 was also demonstrated to transcriptionally regulate the ER promoter in luciferase assays and chromatin immunoprecipitation assays showed that p53 was recruited to the ER promoter along with CARM1, CBP, c-Jun and Sp1 and that this multifactor complex was formed in a p53-dependent manner. The regulation of ER by p53 has therapeutic implications, as the treatment of breast cancer cells with doxorubicin sensitized these cells to tamoxifen treatment. Furthermore, response to tamoxifen as well as to estrogen was dependent on p53 expression in ER positive human breast cancer cells. Taken together, these data demonstrate that p53 regulates ER expression through transcriptional control of the ER promoter, accounting for their concordant expression in human breast cancer and identifying potentially beneficial therapeutic strategies for the treatment of ER positive breast cancers. ^

Antibody chemical reactivity: Beneficial and pathogenic roles

Antibodies (Abs) to autoantigens and foreign antigens (Ags) mediate, respectively, various pathogenic and beneficial effects. Abs express enzyme-like nucleophiles that react covalently with electrophiles. A subpopulation of nucleophilic Abs expresses proteolytic activity, which can inactivate the Ag permanently. This thesis shows how the nucleophilicity can be exploited to inhibit harmful Abs or potentially protect against a virus. ^ Inactivation of pathogenic Abs from Hemophilia A (HA) patients by means of nucleophile-electrophile pairing was studied. Deficient factor VIII (FVIII) in HA subjects impairs blood coagulation. FVIII replacement therapy fails in 20-30% of HA patients due to production of anti-FVIII Abs. FVIII analogs containing electrophilic phosphonate group (E-FVIII and E-C2) were hypothesized to inactivate the Abs by reacting specifically and covalently with nucleophilic sites. Anti-FVIII IgGs from HA patients formed immune complexes with E-FVIII and E-C2 that remained irreversibly associated under conditions that disrupt noncovalent Ab-Ag complexes. The reaction induced irreversible loss of Ab anti-coagulant activity. E-FVIII alone displayed limited interference with coagulation. E-FVIII is a prototype reagent suitable for further development as a selective inactivator of pathogenic anti-FVIII Abs. ^ The beneficial function of Abs to human immunodeficiency virus type 1 (HIV-1) was analyzed. HIV-1 eludes the immune system by rapidly changing its coat protein structure. IgAs from noninfected subjects hydrolyzed gp120 and neutralized HIV-1 with modest potency by recognizing the gp120 421-433 epitope, a conserved B cell superantigenic region that is also essential for HIV-1 attachment to host cell CD4 receptors. An adaptive immune response to superantigens is generally prohibited due to their ability to downregulate B cells. IgAs from subjects with prolonged HIV-1 infection displayed improved catalytic hydrolysis of gp120 and exceptionally potent and broad neutralization of diverse CCR5-dependent primary HIV isolates attributable to recognition of the 421-433 epitope. This indicates that slow immunological bypass of the superantigenic character of gp120 is possible, opening the path to effective HIV vaccination. ^ My research reveals a novel route to inactivate pathogenic nucleophilic Abs using electrophilic antigens. Conversely, naturally occurring nucleophilic Abs may help impede HIV infection, and the Abs could be developed for passive immunotherapy of HIV infected subjects. ^

Antibiotic susceptibility and resistance among bacterial enteropathogens isolated from international travelers to Mexico, Guatemala, and India, 2006--2008

The incidence rates of travelers' diarrhea (TD) have remained unchanged for the last fifty years. More recently, there have been increasing recommendations for self-initiated therapy and even prophylactic therapy for TD. There is no recent data on the in vitro activities of commonly used antibiotics for TD therapy and whether there have been any changes in susceptibilities over the last ten years. 456 enteropathogens were isolated from adult travelers to Mexico, India, and Guatemala between the years 2006 to 2008. MICs were determined for 10 different antimicrobials by the agar dilution method. Traditional antibiotics such as ampicillin, trimethoprim/sulfamethoxazole, and doxycycline continue to show high levels of resistance. Current first line antibiotic agents including fluoroquinolones and azithromycin had significantly higher MICs when compared to 10 years ago and MIC90 levels were beyond the CSLI cutoffs for resistance. There were significant geographical differences in resistance patterns when comparing Central America with India. Entertoxigenic Escherichia coli (ETEC) isolates were more resistant to ciprofloxacin (p=0.023), and levofloxacin (p=0.0078) in India; whereas, enteroaggregative Escherichia coli (EAEC) isolates from Central America showed more resistance. When compared to MICs of isolates 10 years prior, there was a four to ten-fold increase in MIC90s for ceftriaxone, ciprofloxacin, levofloxacin and azithromycin for both ETEC and EAEC. There were no significant changes in rifaximin MICs over the last ten years, which makes it a promising agent for TD. Rising MICs over time implicate the need for continuous surveillance of susceptibility patterns worldwide and for geography specific recommendations in TD therapy.^

Performance recovery from exercise: A review from a statistical point of view

Background. Research into methods for recovery from fatigue due to exercise is a popular topic among sport medicine, kinesiology and physical therapy. However, both the quantity and quality of studies and a clear solution of recovery are lacking. An analysis of the statistical methods in the existing literature of performance recovery can enhance the quality of research and provide some guidance for future studies. Methods: A literature review was performed using SCOPUS, SPORTDiscus, MEDLINE, CINAHL, Cochrane Library and Science Citation Index Expanded databases to extract the studies related to performance recovery from exercise of human beings. Original studies and their statistical analysis for recovery methods including Active Recovery, Cryotherapy/Contrast Therapy, Massage Therapy, Diet/Ergogenics, and Rehydration were examined. Results: The review produces a Research Design and Statistical Method Analysis Summary. Conclusion: Research design and statistical methods can be improved by using the guideline from the Research Design and Statistical Method Analysis Summary. This summary table lists the potential issues and suggested solutions, such as, sample size calculation, sports specific and research design issues consideration, population and measure markers selection, statistical methods for different analytical requirements, equality of variance and normality of data, post hoc analyses and effect size calculation.^

E2F1's role in ultraviolet-induced DNA damage response

The E2F1 transcription factor is a well-known regulator of cell proliferation and apoptosis, but its role in the DNA damage response is less clear. It has been shown that E2F1 becomes stabilized in response to DNA double strand breaks (DSBs) and accumulates at sites of DSBs. This process requires ATM kinase and serine 31 phosphorylation, which provides a binding site for TopBp1. However, the role of E2F1 at sites of DNA damage is not clear. We expanded the study of E2F1's role in the DNA damage response by exploring its functions in ultraviolet (UV) induced DNA damage, and identified that E2F1 promotes DNA repair and cell survival. To further investigate the mechanisms underlying our findings, we examined the possibility for direct involvement of E2F1 in DNA repair. We found that E2F1 localizes to sites of UV irradiation-induced DNA damage dependent on the ATR kinase and serine 31 of E2F1. E2F1 also associates with the GCN5 histone acetyltransferase in response to UV irradiation and recruits GCN5 to sites of DNA damage. This correlates with an increase in histone H3 lysine 9 (H3K9) acetylation and chromatin relaxation. In the absence of E2F1 or GCN5, nucleotide excision repair (NER) proteins do not efficiently localize to sites of UV damage and DNA repair is impaired. E2F1 mutants unable to bind DNA or activate transcription retain the ability to stimulate NER. These findings demonstrate a non-transcriptional role for E2F1 in DNA repair involving GCN5-mediated H3K9 acetylation and increased accessibility to the NER machinery. ^

Role of activation of the protein tyrosine kinase, Src, in colorectal cancer chemoresistance

Advances in therapy for colorectal cancer have been hampered by development of resistance to chemotherapy. The Src family of protein tyrosine kinases has been associated with colorectal cancer development and progression. Activation of the prototypic member of the family, Src, occurs in advanced colorectal cancer and is associated with a worse outcome. This work tests the hypotheses that Src activation contributes to chemoresistance in some colon tumors and that this resistance can be overcome by use of Src inhibitors. The aims of the proposal were to (1) determine if constitutive Src activation is sufficient to induce oxaliplatin resistance; (2) evaluate the role of reactive oxygen species (ROS) in the activation of Src after oxaliplatin treatment; (3) determine the frequency of Src activation in liver metastases after oxaliplatin treatment; and (4) evaluate the safety, preliminary efficacy, and pharmacodynamics of the combination of dasatinib with oxaliplatin-based therapy in patients with metastatic colorectal cancer. ^ Using a panel of colon cancer cell lines and murine models, I demonstrate that administration of oxaliplatin, a commonly utilized chemotherapy for colorectal cancer, results in an increased activation of Src. The activation occurs acutely in some, but not all, colorectal carcinoma cell lines. Cell lines selected for oxaliplatin resistance are further increased in Src activity. Treatment of cell lines with dasatinib, a non-selective pharmacologic inhibitor of the Src family kinases synergistically killed some, but not all cell lines. Cell lines with the highest acute activation of Src after oxaliplatin administration were the most sensitive to the combination therapy. Previous work demonstrated that siRNA to Src increased sensitivity to oxaliplatin, suggesting that the effects of dasatinib are primarily due to its ability to inhibit Src in these cell lines. ^ To examine the mechanism underlying these results, I examined the effects of reactive oxygen species (ROS), as previous studies have demonstrated that platinum chemotherapeutics result in intracellular oxidative stress. I demonstrated that oxaliplatin-induced reactive oxygen species were higher in the cell lines with Src activation, relative to those in which Src was not activated. This oxaliplatin-induced Src activation was blocked by the administration of anti-oxidants, thereby demonstrating that synergistic killing between dasatinib and oxaliplatin was associated with the ability of the latter to generate ROS. ^ In a murine model of colorectal cancer metastasis to the liver, the combination of dasatinib and oxaliplatin was more effective in reducing tumor volume than either agent alone. However, when oxaliplatin resistant cell lines were treated with a combination of oxaliplatin and AZD0530, an inhibitor in the clinic with increased specificity for Src, no additional benefit was seen, although Src was activated by oxaliplatin and Src substrates were inhibited. The indolent growth of oxaliplatin-resistant cells, unlike the growth of oxaliplatin resistant tumors in patients, precludes definitive interpretation of these results. ^ To further explore Src activation in patients with oxaliplatin exposure and resistance, an immunohistochemistry analysis of tumor tissue from resected liver metastases of colorectal cancer was performed. Utilizing a tissue microarray, staining for phosphorylated Src and FAK demonstrated strong staining of tumor relative to stromal and normal liver. In patients recently exposed to oxaliplatin, there was increased FAK activation, supporting the clinical relevance of the prior preclinical studies. ^ To pursue the potential clinical benefit of the combination of Src inhibition with oxaliplatin, a phase IB clinical trial was completed. Thirty patients with refractory metastatic colorectal cancer were treated with a combination of 5-FU, oxaliplatin, an epidermal-growth factor receptor monoclonal antibody, and dasatinib. The recommended phase II dose of dasatinib was established, and toxicities were quantified. Pharmacodynamic studies demonstrated increased phosphorylation of the Src substrate paxillin after dasatinib therapy. Tumor biopsies were obtained and Src expression levels were quantitated. Clinical benefit was seen with the combination, including a response rate of 20% and disease control rate of 56%, prompting a larger clinical study. ^ In summary, although Src is constitutively activated in metastatic colorectal cancer, administration of oxaliplatin chemotherapy can further increase its activity, through a reactive oxygen species dependent manner. Inhibition of Src in combination with oxaliplatin provides additional benefit in vitro, in preclinical animal models, and in the clinic. Further study of Src inhibition in the clinic and identification of predictive biomarkers of response will be required to further advance this promising therapeutic target. ^

Metabolic syndrome and cardiovascular mortality among participants of the hypertension detection and follow-up program

Metabolic Syndrome (MetS) is a clustering of cardiovascular (CV) risk factors that includes obesity, dyslipidemia, hyperglycemia, and elevated blood pressure. Applying the criteria for MetS can serve as a clinically feasible tool for identifying patients at high risk for CV morbidity and mortality, particularly those who do not fall into traditional risk categories. The objective of this study was to examine the association between MetS and CV mortality among 10,940 American hypertensive adults, ages 30-69 years, participating in a large randomized controlled trial of hypertension treatment (HDFP 1973-1983). MetS was defined as the presence of hypertension and at least two of the following risk factors: obesity, dyslipidemia, or hyperglycemia. Of the 10,763 individuals with sufficient data available for analysis, 33.2% met criteria for MetS at baseline. The baseline prevalence of MetS was significantly higher among women (46%) than men (22%) and among non-blacks (37%) versus blacks (30%). All-cause and CV mortality was assessed for 10,763 individuals. Over a median follow-up of 7.8 years, 1,425 deaths were observed. Approximately 53% of these deaths were attributed to CV causes. Compared to individuals without MetS at baseline, those with MetS had higher rates of all-cause mortality (14.5% v. 12.6%) and CV mortality (8.2% versus 6.4%). The unadjusted risk of CV mortality among those with MetS was 1.31 (95% confidence interval [CI], 1.12-1.52) times that for those without MetS at baseline. After multiple adjustment for traditional risk factors of age, race, gender, history of cardiovascular disease (CVD), and smoking status, individuals with MetS, compared to those without MetS, were 1.42 (95% CI, 1.20-1.67) times more likely to die of CV causes. Of the individual components of MetS, hyperglycemia/diabetes conferred the strongest risk of CV mortality (OR 1.73; 95% CI, 1.39-2.15). Results of the present study suggest MetS defined as the presence of hypertension and 2 additional cardiometabolic risk factors (obesity, dyslipidemia, or hyperglycemia/diabetes) can be used with some success to predict CV mortality in middle-aged hypertensive adults. Ongoing and future prospective studies are vital to examine the association between MetS and cardiovascular morbidity and mortality in select high-risk subpopulations, and to continue evaluating the public health impact of aggressive, targeted screening, prevention, and treatment efforts to prevent future cardiovascular disability and death.^

Evaluation of risk factors for long term changes in refractive error among adult patients at a Dallas Texas private setting A retrospective chart-review study

Background. Over 39.9% of the adult population forty or older in the United States has refractive error, little is known about the etiology of this condition and associated risk factors and their entailed mechanism due to the paucity of data regarding the changes of refractive error for the adult population over time.^ Aim. To evaluate risk factors over a long term, 5-year period, in refractive error changes among persons 43 or older by testing the hypothesis that age, gender, systemic diseases, nuclear sclerosis and baseline refractive errors are all significantly associated with refractive errors changes in patients at a Dallas, Texas private optometric office.^ Methods. A retrospective chart review of subjective refraction, eye health, and self-report health history was done on patients at a private optometric office who were 43 or older in 2000 who had eye examinations both in 2000 and 2005. Aphakic and pseudophakic eyes were excluded as well as eyes with best corrected Snellen visual acuity of 20/40 and worse. After exclusions, refraction was obtained on 114 right eyes and 114 left eyes. Spherical equivalent (sum of sphere + ½ cylinder) was used as the measure of refractive error.^ Results. Similar changes in refractive error were observed for the two eyes. The 5-year change in spherical power was in a hyperopic direction for younger age groups and in a myopic direction for older subjects, P<0.0001. The gender-adjusted mean change in refractive error in right eyes of persons aged 43 to 54, 55 to 64, 65 to 74, and 75 or older at baseline was +0.43D, +0.46 D, -0.09 D, and -0.23D, respectively. Refractive change was strongly related to baseline nuclear cataract severity; grades 4 to 5 were associated with a myopic shift (-0.38 D, P< 0.0001). The mean age-adjusted change in refraction was +0.27 D for hyperopic eyes, +0.56 D for emmetropic eyes, and +0.26 D for myopic eyes.^ Conclusions. This report has documented refractive error changes in an older population and confirmed reported trends of a hyperopic shift before age 65 and a myopic shift thereafter associated with the development of nuclear cataract.^

Impact of real time polymerase chain reaction technology on the therapeutic approach to treatment of staphylococcal infections

Can the early identification of the species of staphylococcus responsible for infection by the use of Real Time PCR technology influence the approach to the treatment of these infections? ^ This study was a retrospective cohort study in which two groups of patients were compared. The first group, ‘Physician Aware’ consisted of patients in whom physicians were informed of specific staphylococcal species and antibiotic sensitivity (using RT-PCR) at the time of notification of the gram stain. The second group, ‘Physician Unaware’ consisted of patients in whom treating physicians received the same information 24–72 hours later as a result of blood culture and antibiotic sensitivity determination. ^ The approach to treatment was compared between ‘Physician Aware’ and ‘Physician Unaware’ groups for three different microbiological diagnoses—namely MRSA, MSSA and no-SA (or coagulase negative Staphylococcus). ^ For a diagnosis of MRSA, the mean time interval to the initiation of Vancomycin therapy was 1.08 hours in the ‘Physician Aware’ group as compared to 5.84 hours in the ‘Physician Unaware’ group (p=0.34). ^ For a diagnosis of MSSA, the mean time interval to the initiation of specific anti-MSSA therapy with Nafcillin was 5.18 hours in the ‘Physician Aware’ group as compared to 49.8 hours in the ‘Physician Unaware’ group (p=0.007). Also, for the same diagnosis, the mean duration of empiric therapy in the ‘Physician Aware’ group was 19.68 hours as compared to 80.75 hours in the ‘Physician Unaware’ group (p=0.003) ^ For a diagnosis of no-SA or coagulase negative staphylococcus, the mean duration of empiric therapy was 35.65 hours in the ‘Physician Aware’ group as compared to 44.38 hours in the ‘Physician Unaware’ group (p=0.07). However, when treatment was considered a categorical variable and after exclusion of all cases where anti-MRS therapy was used for unrelated conditions, only 20 of 72 cases in the ‘Physician Aware’ group received treatment as compared to 48 of 106 cases in the ‘Physician Unaware’ group. ^ Conclusions. Earlier diagnosis of MRSA may not alter final treatment outcomes. However, earlier identification may lead to the earlier institution of measures to limit the spread of infection. The early diagnosis of MSSA infection, does lead to treatment with specific antibiotic therapy at an earlier stage of treatment. Also, the duration of empiric therapy is greatly reduced by early diagnosis. The early diagnosis of coagulase negative staphylococcal infection leads to a lower rate of unnecessary treatment for these infections as they are commonly considered contaminants. ^