GD3 synthase regulates epithelial-mesenchymal transition and metastasis in breast cancer

The epithelial-mesenchymal transition (EMT) bestows cancer cells with increased stem cell properties and metastatic potential. To date, multiple extracellular stimuli and transcription factors have been shown to regulate EMT. Many of them are not druggable and therefore it is necessary to identify targets, which can be inhibited using small molecules to prevent metastasis. Recently, we identified the ganglioside GD2 as a novel breast cancer stem cell marker. Moreover, we found that GD3 synthase (GD3S)--an enzyme involved in GD2 biosynthesis--is critical for GD2 production and could serve as a potential druggable target for inhibiting tumor initiation and metastasis. Indeed, there is a small molecule known as triptolide that has been shown to inhibit GD3S function. Accordingly, in this manuscript, we demonstrate that the inhibition of GD3S using small hairpin RNA or triptolide compromises the initiation and maintenance of EMT instigated by various signaling pathways, including Snail, Twist and transforming growth factor-β1 as well as the mesenchymal characteristics of claudin-low breast cancer cell lines (SUM159 and MDA-MB-231). Moreover, GD3S is necessary for wound healing, migration, invasion and stem cell properties in vitro. Most importantly, inhibition of GD3S in vivo prevents metastasis in experimental as well as in spontaneous syngeneic wild-type mouse models. We also demonstrate that the transcription factor FOXC2, a central downstream effector of several EMT pathways, directly regulates GD3S expression by binding to its promoter. In clinical specimens, the expression of GD3S correlates with poor prognosis in triple-negative human breast tumors. Moreover, GD3S expression correlates with activation of the c-Met signaling pathway leading to increased stem cell properties and metastatic competence. Collectively, these findings suggest that the GD3S-c-Met axis could serve as an effective target for the treatment of metastatic breast cancers.

A population-based study of Kaposi Sarcoma-associated herpesvirus seropositivity in Uganda using principal components analysis

Background

Kaposi sarcoma-associated herpesvirus (KSHV) seropositivity is associated with sexual, environmental, and socioeconomic exposures. Whether these characteristics are independent risk factors is uncertain because of reliance on selected high-risk or hospital-based populations and incomplete adjustment for confounding. Therefore, we evaluated risk factors for KSHV seropositivity in a population-based study in Uganda using principal components analysis (PCA).

Methods

The study population comprised 2,681 individuals randomly selected from a nationally-representative population-based HIV/AIDS sero-behavioral survey conducted in 2004/05. Questionnaire and laboratory data (97 variables) were transformed into a smaller set of uncorrelated variables using PCA. Multivariable logistic regression models were fitted to estimate odds ratios and 95% confidence intervals for the association between components and KSHV seropositivity.

Results

Data were reduced to three principal components (PCs) labeled as Sexual behavioral, Socioeconomic, and Knowledge PCs. In crude analysis, KSHV seropositivity was associated with the Knowledge (p_trend = 0.012) and Socioeconomic components (p_trend = 0.0001), but not with the Sexual-behavioral component (p_trend = 0.066). KSHV seropositivity was associated with the Socioeconomic PC (p_trend = 0.037), but not with the Sexual-behavioral and Knowledge PCs, in the models including PCs, age, gender and geographic region.

Conclusions

Our results fit with the view that in Uganda socioeconomic characteristic may influence KSHV seropositivity. Conversely, the results fit with the interpretation that in Uganda sexual-behavioral characteristics, if relevant, contribute minimally.

Abstract 5487: Investigating human herpesvirus 8 infection among adults in Uganda: A factor analysis approach

Objective: Human Herpesvirus 8 (HHV8) is highly prevalent in Uganda, and it is a necessary agent for Kaposi Sarcoma (KS). During the AIDS era, KS became epidemic. There is some evidence but limited information on sexual transmission, and prevalence varies by age, sex and region. However, current knowledge about HHV8 is based on selected populations including hospital-based samples and high-risk cohort groups, which may be biased. Methods: We analyzed a subset of the Uganda HIV/AIDS serobehavioral survey (UHSBS) 04/05 to estimate the association with risk factors and HHV8 seropositivity. HHV8 seropositivity was determined using HHV8 K8.1 and orf65 glycoproteins. Odds ratios and 95% confidence intervals (CIs) were determined and components were obtained by Principal Component Analysis (PCA). Results: Among 2,681 individuals tested, HHV8 seropositivity was 55.4% (95% CI, 53.0%-57.8%). Three components were identified by PCA: sexual behavioral, socioeconomic, and cultural components. In bivariate analysis, HHV8 seropositivity was positively associated with sexual behavioral (ORquartile2=1.39, ORquartile3=1.37, ORquartile4=1.27, and Ptrend=0.1085) and cultural components (ORquartile2=1.29, ORquartile3=1.39, ORquartile4=1.59, and Ptrend=0.0024), but inversely associated with socioeconomic component (ORquartile2=0.77, ORquartile3=0.65, ORquartile4=0.59, and Ptrend<0.0001). Multivariable analysis showed that HHV8 seropositivity was strongly associated with the socioeconomic component but not the other when adjusted by age, sex and region (Ptrend=0.0137). Conclusions: HHV8 infection in Uganda adults was strongly associated with lower socioeconomic status with age, sex and region adjusted but weakly associated with sexual behavioral and cultural characteristics. Lower socioeconomic class can be an indicator of having less education, poorer nutrition, and worse sanitation, which might enhance HHV8 transmission. As socioeconomic status improves over time, HHV8 seroprevalence might decline in this population.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5487. doi:1538-7445.AM2012-5487

Aryl hydrocarbon receptor in association with RelA modulates IL-6 expression in non-smoking lung cancer

Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that is activated by cigarette smoke. Previously, we demonstrated that AhR is overexpressed in lung adenocarcinomas (ADs). In this study we observed that AhR expression is significantly correlated with nuclear RelA (a nuclear factor-κB (NFκB) subunit) and cytosolic interleukin-6 (IL-6) in 200 non-small cell lung cancer patients, especially among never smokers. Overexpression of AhR increased IL-6 expression in H1355 cells and immortalized human bronchial epithelial cells BEAS-2B. As NFκB inhibitor and knockdown RelA expression greatly reduced constitutive AhR-induced IL-6 expression, we hypothesized that AhR expression, in the absence of exogenous ligand, is able to modulate NFκB activity and subsequently upregulate IL-6 expression, thus promoting the development of lung AD. Specifically, AhR overexpression significantly increased NFκB activity, whereas interference with AhR expression significantly reduced NFκB activity and IL-6 expression in H1355 cells. We demonstrated that AhR associates with RelA in the cytosol and nucleus of human lung cells. Furthermore, AhR overexpression enhanced nuclear localization of AhR and RelA, and increased the association of AhR-RelA with the NFκB response element of the IL-6 promoter. However, p50 was not involved. Our results indicate that AhR, without exposure to a ligand, associates with RelA, which then positively modulates NFκB activity and then upregulates IL-6 expression in human lung cells. Thus we have identified a new mechanism for lung tumorigenesis in non-smokers.

Anchorage-independent cell growth signature identifies tumors with metastatic potential

The oncogenic phenotype is complex, resulting from the accumulation of multiple somatic mutations that lead to the deregulation of growth regulatory and cell fate controlling activities and pathways. The ability to dissect this complexity, so as to reveal discrete aspects of the biology underlying the oncogenic phenotype, is critical to understanding the various mechanisms of disease as well as to reveal opportunities for novel therapeutic strategies. Previous work has characterized the process of anchorage-independent growth of cancer cells in vitro as a key aspect of the tumor phenotype, particularly with respect to metastatic potential. Nevertheless, it remains a major challenge to translate these cell biology findings into the context of human tumors. We previously used DNA microarray assays to develop expression signatures, which have the capacity to identify subtle distinctions in biological states and can be used to connect in vitro and in vivo states. Here we describe the development of a signature of anchorage-independent growth, show that the signature exhibits characteristics of deregulated mitochondrial function and then demonstrate that the signature identifies human tumors with the potential for metastasis.

Asymmetric division and stem cell renewal without a permanent niche: lessons from lymphocytes

Numerous tissues in long-lived organisms are composed of short-lived cells. The continual regeneration of some barrier surfaces, for example, relies on adult stem cells that have the capacity to divide and produce one daughter cell destined for terminal differentiation and function and another daughter cell that renews the stem cell fate. The immune system of higher animals possesses a cellular component called lymphocytes, which face a similar need for regeneration. A lymphocyte that is recruited during an infection must give rise to cellular progeny that undergo terminal differentiation to eliminate an invading microbe, yet retain progeny that replace the recruited cell in order to maintain immunity to reinfection. Emerging evidence suggests that specifying the divergent cell fates necessary for immunity relies on the ability of the lymphocyte to exploit an evolutionarily conserved strategy for making kindred cells different--asymmetric cell division. Although the lymphocyte does not possess constitutive polarity, it appears to use a facultative interaction with another cell to nucleate unequal segregation of fate determinants relative to its plane of division. Herein, we propose that other mobile and nonadherent cells, such as blood and cancer stem cells, might exploit provisional interactions with their niche or microenvironment to achieve diversity among their daughter cells.

Compensation and specificity of function within the E2F family

Functions encoded by single genes in lower organisms are often represented by multiple related genes in the mammalian genome. An example is the retinoblastoma and E2F families of proteins that regulate transcription during the cell cycle. Analysis of gene function using germline mutations is often confounded by overlapping function resulting in compensation. Indeed, in cells deleted of the E2F1 or E2F3 genes, there is an increase in the expression of the other family member. To avoid complications of compensatory effects, we have used small-interfering RNAs that target individual E2F proteins to generate a temporary loss of E2F function. We find that both E2F1 and E2F3 are required for cells to enter the S phase from a quiescent state, whereas only E2F3 is necessary for the S phase in growing cells. We also find that the acute loss of E2F3 activity affects the expression of genes encoding DNA replication and mitotic activities, whereas loss of E2F1 affects a limited number of genes that are distinct from those regulated by E2F3. We conclude that the long-term loss of E2F activity does lead to compensation by other family members and that the analysis of acute loss of function reveals specific and distinct roles for these proteins.

DSG3 is overexpressed in head neck cancer and is a potential molecular target for inhibition of oncogenesis

To identify genes that could potentially serve as molecular therapeutic markers for human head and neck cancer (HNC), we employed differential display analysis to compare the gene expression profiles between HNC and histopathologically normal epithelial tissues. Using reverse transcription-polymerase chain reaction and Western blot analysis, desmoglein 3 (DSG3) was identified as being differentially expressed at both the RNA and protein levels. Of 56 patients assayed, 34 (61%) had overexpression of DSG3, which correlated statistically with T stage (P=0.009), N stage (P=0.047), overall stage (P=0.011), tumor depth (P=0.009) and extracapsular spread in lymph nodes (P=0.044), suggesting that DSG3 participates in carcinogenesis of HNC. Consistent with the clinical findings, inhibition of DSG3 by RNA interference (RNAi) significantly reduced cell growth and colony formation to 57-21% in three HNC cell lines. Use of an in vitro wound healing and Matrigel invasion assays, we found that cell migration and invasive ability were also inhibited to 30-48% in three cell lines tested. An in vivo xenograft study showed that administration of DSG3-RNAi plasmid significantly inhibited tumor growth for 2 months in BALB/C nude mice. In conclusion, DSG3 is identified overexpressed in HNC, with the degree of overexpression associated with clinicopathologic features of the tumor. Inhibition of DSG3 significantly suppresses carcinogenic potential in cellular and in vivo animal studies. These findings suggest that DSG3 is a potential molecular target in the development of adjuvant therapy for HNC.

hTERT phosphorylation by PKC is essential for telomerase holoprotein integrity and enzyme activity in head neck cancer cells

Telomerase activity is suppressed in normal somatic tissues but is activated in most cancer cells. We have previously found that all six telomerase subunit proteins, including hTERT and hsp90 are needed for full enzyme activity. Telomerase activity has been reported to be upregulated by protein kinase C (PKC), but the mechanism is not clear. In this study, we examined how PKC regulates telomerase activity in head and neck cancer cells. PKC inhibitor, bisindolylmaleimide I (BIS), inhibited telomerase activity but had no effect on the expressions of telomerase core subunits. RNA interference (RNAi) and in vitro phosphorylation studies revealed that PKC isoforms α, β, δ, ε, ζ specifically involved in telomerase regulation, and the phosphorylation target was on hTERT. Treatment with the hsp-90 inhibitor novobiocin dissociated hsp90 and hTERT as revealed by immunoprecipitation and immunoblot analysis and reduced telomerase activity. Treatment with the PKC activator SC-10 restored the association of hsp90 and hTERT and reactivate telomerase, suggesting that hTERT phosphorylation by PKC is essential for telomerase holoenzyme integrity and function. Analysis on clinical normal and tumour tissues reveal that the expressions of PKC α, β, δ, ε, ζ were higher in the tumour tissues, correlated with telomerase activity. Disruption of PKC phosphorylation by BIS significantly increased chemosensitivity to cisplatin. In conclusion, PKC isoenzymes α, β, δ, ε, ζ regulate telomerase activity in head and neck cancer cells by phosphorylating hTERT. This phosphorylation is essential for telomerase holoenzyme assembly, leading to telomerase activation and oncogenesis. Manipulation of telomerase activity by PKC inhibitors is worth exploring as an adjuvant therapeutic approach.

False positive fluorine-18 fluorodeoxy-D-glucose positron emission tomography finding caused by osteoradionecrosis in a nasopharyngeal carcinoma patient

Nasopharyngeal carcinoma (NPC) is treated by radiotherapy with or without chemotherapy. It is not uncommon to find the residual/recurrent lesion in the skull base area. For patients who had received radiotherapy, it is difficult to differentiate the skull base tumour from post-treatment change in the CT or MRI. (18)F-2-fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) provides an alternative diagnostic choice in this situation for head and neck cancer including NPC especially when there is inconclusive CT/MRI finding. This report of an NPC patient who received radiotherapy 18 months previously, describes the misdiagnosis of tumour recurrence at the skull base found in both MRI and FDG PET scan. Histopathological studies showed osteoradionecrosis of the debrided tissue and follow-up PET showed complete regression of the skull base lesion. Therefore, a false positive result in FDG PET caused by osteoradionecrosis was confirmed. To the best of our knowledge, this is the first case report in the literature.

Prognostic significance of EGFR and Her-2 in oral cavity cancer in betel quid prevalent area cancer prognosis

Although several studies have found overexpression of epidermal growth factor receptor (EGFR) proteins EGFR and Her-2 in head and neck cancers, the clinical relevance of the finding varies. We examined the expression and clinical association of these molecules with oral squamous cell carcinoma in an area where betel chewing is prevalent. EGFR and Her-2 proteins were measured in 59 paired (grossly normal and cancer) tissues by an enzyme immunoassy method. The cutoff value for gene overexpression was defined as the level of mean expression in normal tissue plus two s.d. A total of 59% of the patients consumed alcohol, 90% smoked tobacco, and 90% chewed betel quid. Of the patients assayed, 34 (58%) and 24 (41%) had EGFR and Her-2 overexpression, with average 3.5- and 1.5-fold elevations. EGFR overexpression has been shown to be statistically associated with T stage, N stage, overall TMN stage, primary tumour depth, lymph node extra-capsular spread, and poor survival. Her-2 overexpression, however, did not demonstrate a similar association with clinicopathological parameters or therapeutic outcome. On multivariant analysis, EGFR overexpression (P=0.041) and N stage (P=0.024) were the only independent factors for overall survival. These results indicate that the molecular targeting therapy to EGFR may be a treatment for oral cavity cancer in the betel quid-chewing prevalent area.

Isolated paraaortic lymph node recurrence after definitive irradiation for cervical carcinoma

PURPOSE

To evaluate the clinical features of isolated paraaortic lymph node (PALN) recurrence after definitive radiotherapy, and analyze the prognostic factors and effect of salvage treatment.

METHODS AND MATERIALS

Of a total 876 patients who received pelvic radiotherapy after the diagnosis of primary cervical carcinoma, 26 were found to have isolated PALN recurrence as the first recurrent site, and these patients enrolled in this study. Only those with primary-site carcinoma controlled and who were free of other distant metastases were eligible. Nineteen of the 26 patients accepted salvage therapy. Fourteen patients accepted concurrent chemoradiation (CCRT), 1 accepted radiation to the paraaortic region, and 4 accepted chemotherapy alone. Clinical parameters evaluated included tumor markers (SCC and CEA) and image studies.

RESULTS

Seven of the 26 patients were alive and disease-free. All 7 survivors had salvage treatment with radiation to the paraaortic region and concurrent cisplatin-based chemotherapy. None of the patients receiving chemotherapy or radiation alone enjoyed long-term, disease-free survival. The 5-year survival rate for isolated PALN recurrence of the 14 patients who accepted salvage concurrent chemoradiation (CCRT) was 51.2%. The presence of a clinical symptom at the time of PALN recurrence was analyzed. Seven of the 12 asymptomatic patients and none of the 14 symptomatic patients survived without disease after salvage treatment. The SCC levels at recurrence showed a statistically significant relationship to disease-free survival.

CONCLUSIONS

An SCC level of < or = 4 ng/ml and a lack of symptoms at the time of recurrence were good prognostic factors in isolated PALN recurrence after primary radiation therapy. In addition to concurrent CCRT, periodical surveillance with tumor markers and imaging studies allowed early detection and salvage of those patients.

Characteristics of mutations in the p53 gene in oral squamous cell carcinoma associated with betel quid chewing and cigarette smoking in Taiwanese

p53 mutations are etiologically associated with the development of oral squamous cell carcinomas (OSCCs) or are associated with exposure to specific carcinogens. In this study, we used PCR-single strand conformation polymorphism and DNA sequencing to analyze the conserved regions of the p53 gene (exons 5-9) in OSCC tumor specimens from 187 patients with varied histories of betel quid, tobacco and alcohol use. Ninety-one of the 187 OSCCs (48.66%) showed p53 gene mutations at exons 5-9. The incidence of p53 mutations was not associated with age, sex, TNM stage, status of cigarette smoking or betel quid chewing. However, alcohol drinkers exhibited a significantly higher incidence (57/101, 56.44%) of p53 mutations than non-users (39.53%, 34/86) (P = 0.02). The effect of alcohol on the incidence of p53 mutations was still statistically significant (RR = 2.24; 95% CI, 1.21-4.15) after adjustment for cigarette smoking and betel quid (BQ) chewing. G:C to A:T transitions were the predominant mutations observed and associated with BQ and tobacco use. Alcohol drinking could enhance these transitions. After adjustment for cigarette smoking and BQ chewing, alcohol drinking still showed an independent effect on G:C to A:T transitions (RR = 2.41; 95% CI, 1.01-5.74). These findings strongly suggest an important contributive role of tobacco carcinogens to p53 mutation in this series of Taiwanese OSCCs and alcohol might enhance these mutagenic effects. As safrole-DNA adducts have been detected in 77% (23/30) of the OSCC tissues from Taiwanese oral cancer patients with a BQ chewing history, we cannot rule out the possibility that safrole or other carcinogens present in the BQ may cause a similar pattern of mutagenesis. Determination of the role of safrole and other carcinogens present in BQ on the pattern of p53 gene mutation in OSCC will require further study.

Methodology standards associated with quality reporting in clinical studies in pediatric surgery journals

BACKGROUND/PURPOSE

Reports of clinical trials often lack adequate descriptions of design and analysis; recent attention has focused on improving this omission so readers can properly assess the strength of the findings and draw their own conclusions. Similar analysis of study design and methodologic standards associated with quality reporting has not been carried out for pediatric surgery journals.

METHODS

All studies (n = 642) published in 1998 in Journal of Pediatric Surgery (JPS) and Pediatric Surgery International (PSI), were reviewed for demographic data and study design. The frequency of reporting of 11 basic elements of design and analysis was evaluated in randomized clinical trials (RCT), nonrandomized clinical trials (NRCT), and retrospective cohorts (RC) from JPS by consensus of 2 assessors.

RESULTS

Of the 642 studies, 17% of articles (111 of 642) were classified as clinical studies. Sixty-three were comparative studies and consisted of RC (n = 48), NRCT (n = 12), and RCT (n = 3). Two-thirds of articles published were either case reports or case series (431 of 642), and 16% were basic science articles. Demographic analysis showed a wide range of topics addressed, 4 authors per article, and multiple country of origin of authors. More than 66% of all RCT in JPS reported on eligibility criteria, admission before allocation, random allocation, method of randomization, patients' blindness to treatment, treatment complications, statistical analyses, statistical methods, loss to follow-up, and statistical methods; 2 elements of design and analysis, however, were poorly reported: blind assessment of outcome (33%) and power (17%).

CONCLUSIONS

There were few randomized, controlled trials in pediatric surgery journals, and further attention should be given to evaluate the causal factors. Nine elements of quality reporting were well reported; however, 2 others were poorly reported; this may improve if editors of pediatric surgical journals provide authors with guidelines on how to report clinical trial design and analysis.

Basic microarray analysis: grouping and feature reduction

DNA microarray technologies are useful for addressing a broad range of biological problems - including the measurement of mRNA expression levels in target cells. These studies typically produce large data sets that contain measurements on thousands of genes under hundreds of conditions. There is a critical need to summarize this data and to pick out the important details. The most common activities, therefore, are to group together microarray data and to reduce the number of features. Both of these activities can be done using only the raw microarray data (unsupervised methods) or using external information that provides labels for the microarray data (supervised methods). We briefly review supervised and unsupervised methods for grouping and reducing data in the context of a publicly available suite of tools called CLEAVER, and illustrate their application on a representative data set collected to study lymphoma.

Poor prognosis in nasopharyngeal cancer patients with low glucose-6-phosphate-dehydrogenase activity

Nasopharyngeal carcinoma (NPC) is endemic among well-defined ethnic groups in several world regions, such as Southeastern China and Taiwan. Glucose-6-phosphate-dehydrogenase (G6PD)- deficiency, a sex-linked disorder, is one of the most common enzymopathies in Taiwan. The major role of G6PD is to generate NADPH to protect cells from oxidative damage, which is a major contributing factor to certain degenerative diseases, such as aging and cancer. In view of the coincidence of epidemic distribution of NPC and G6PD deficiency, as well as the house-keeping function of G6PD in cellular oxidative defense, we investigated the correlation of G6PD activity with NPC. The stage of NPC was classified by AJCC (1997) criteria. G6PD levels were determined in 108 NPC male patients and 75 healthy male individuals. The mean G6PD level of NPC patients was 218.9 U/10(12) RBC or 7.53 U/g hemoglobin (Hb), being much lower than in normal individuals (260.6 U/10(12) erythrocytes (RBC) or 8.92 U / gHb). The level of G6PD activity had no correlation with tumor stage or lymph node or distant metastasis, but was significantly correlated with tumor recurrence (P = 0.004 when using G6PD = 130 U/10(12) RBC as cutoff value). These results indicated that low G6PD activity in patients with NPC is associated with poor prognosis.

Expression and permeation properties of the K(+) channel Kir7.1 in the retinal pigment epithelium

Bovine Kir7.1 clones were obtained from a retinal pigment epithelium (RPE)-subtracted cDNA library. Human RPE cDNA library screening resulted in clones encoding full-length human Kir7.1. Northern blot analysis indicated that bovine Kir7.1 is highly expressed in the RPE. Human Kir7.1 channels were expressed in Xenopus oocytes and studied using the two-electrode voltage-clamp technique. The macroscopic Kir7.1 conductance exhibited mild inward rectification and an inverse dependence on extracellular K+ concentration ([K+]o). The selectivity sequence based on permeability ratios was K+ (1.0) approximately Rb+ (0.89) > Cs+ (0.013) > Na+ (0.003) approximately Li+ (0.001) and the sequence based on conductance ratios was Rb+ (9.5) >> K+ (1.0) > Na+ (0.458) > Cs+ (0.331) > Li+ (0.139). Non-stationary noise analysis of Rb+ currents in cell-attached patches yielded a unitary conductance for Kir7.1 of approximately 2 pS. In whole-cell recordings from freshly isolated bovine RPE cells, the predominant current was a mild inwardly rectifying K+ current that exhibited an inverse dependence of conductance on [K+]o. The selectivity sequence based on permeability ratios was K+ (1.0) approximately Rb+ (0.89) > Cs+ (0.021) > Na+ (0.003) approximately Li+ (0.002) and the sequence based on conductance ratios was Rb+ (8.9) >> K+ (1.0) > Na+ (0.59) > Cs+ (0.23) > Li+ (0.08). In cell-attached recordings with Rb+ in the pipette, inwardly rectifying currents were observed in nine of 12 patches of RPE apical membrane but in only one of 13 basolateral membrane patches. Non-stationary noise analysis of Rb+ currents in cell-attached apical membrane patches yielded a unitary conductance for RPE Kir of approximately 2 pS. On the basis of this molecular and electrophysiological evidence, we conclude that Kir7.1 channel subunits comprise the K+ conductance of the RPE apical membrane.

Including biological literature improves homology search

Annotating the tremendous amount of sequence information being generated requires accurate automated methods for recognizing homology. Although sequence similarity is only one of many indicators of evolutionary homology, it is often the only one used. Here we find that supplementing sequence similarity with information from biomedical literature is successful in increasing the accuracy of homology search results. We modified the PSI-BLAST algorithm to use literature similarity in each iteration of its database search. The modified algorithm is evaluated and compared to standard PSI-BLAST in searching for homologous proteins. The performance of the modified algorithm achieved 32% recall with 95% precision, while the original one achieved 33% recall with 84% precision; the literature similarity requirement preserved the sensitive characteristic of the PSI-BLAST algorithm while improving the precision.

A Case of Malingering: Feigning a Painful Disorder in the Presence of True Medical Illness

The potential for malingering must always be considered among patients presenting with pain. When malingering is identified, care may be discontinued. This case report describes a patient who feigned sickle cell crisis, a painful condition, in the presence of other identifiable and potentially painful medical illnesses.

Requirements for the maintenance of Th1 immunity in vivo following DNA vaccination: a potential immunoregulatory role for CD8+ T cells

Protective immunity against Leishmania major generated by DNA encoding the LACK (Leishmania homologue of receptor for activated C kinase) Ag has been shown to be more durable than vaccination with LACK protein plus IL-12. One mechanism to account for this may be the selective ability of DNA vaccination to induce CD8+ IFN-gamma-producing T cells. In this regard, we previously reported that depletion of CD8+ T cells in LACK DNA-vaccinated mice abrogated protection when infectious challenge was done 2 wk postvaccination. In this study, we extend these findings to study the mechanism by which CD8+ T cells induced by LACK DNA vaccination mediate both short- and long-term protective immunity against L. major. Mice vaccinated with LACK DNA and depleted of CD8+ T cells at the time of vaccination or infection were unable to control infection when challenge was done 2 or 12 wk postvaccination. Remarkably, it was noted that depletion of CD8+ T cells in LACK DNA-vaccinated mice was associated with a striking decrease in the frequency of LACK-specific CD4+ IFN-gamma-producing T cells both before and after infection. Moreover, data are presented to suggest a mechanism by which CD8+ T cells exert this regulatory role. Taken together, these data provide additional insight into how Th1 cells are generated and sustained in vivo and suggest a potentially novel immunoregulatory role for CD8+ T cells following DNA vaccination.

The effect of nodal status on determinants of initial treatment response and patterns of relapse-free survival in nasopharyngeal carcinoma

PURPOSE

To study the effect of regional nodal status on predictors of treatment response, failure patterns, and the time-dependent nature of the various pattern of relapse via a hazard function analysis.

METHODS AND MATERIALS

We reviews tumor control data of 496 patients with nasopharyngeal carcinoma (NPC) to whom a radical course of radiotherapy (RT) with or without induction chemotherapy (CT) was given. All alive patients had a median follow-up period of 131 months. Primary tumor (T) and nodal (N) status were staged according to the TNM system of the American Joint Committee. Remote after-loading brachytherapy may be added to teletherapy in T1-2 lesions while induction CT could be given for N3 and/or T4 lesions. Hazard function analysis over 1-year interval was carried out for locoregional or distant relapse.

RESULTS

T stage and brachytherapy were two independent predictors for complete response (CR) at the primary site irrespective of nodal status, whereas N stage and brachytherapy are major determinants for regional CR in node (+) patients. Multivariate analysis revealed that contributors to a relatively long disease-free interval in (1) node (-) patients were for locoregional relapse, induction CT(-) (p = 0.0062) or brachytherapy (+) (p = 0.0268) and for distant relapse, none; (2) node (+) patients were for locoregional relapse, early T stage (p = 0.0377) or regional CR (p = 0.0075) and for distant relapse, induction CT(-) (p = 0.0001) or regional CR (p = 0.0001). In node (-) or (+) patients, primary CR rate yield no independent prognostic value on various types of disease-free survival. Hazard function analysis for relapse revealed that hazard rates are in general negatively correlated with time, being highest at the first year post-treatment, decreasing from time to time, and approaching zero after a longer follow-up period in patients with locoregional CR than in patients without.

CONCLUSION

Nodal status had no significant impact on predictors of primary CR, whereas in node (+) patients regional CR rate had an independent value in predicting disease-free survival to locoregional and distant relapse. Hazard function analysis revealed a decreasing hazard rate over a protracted post-treatment time in primary and regional CR patients. This indicates the continued risk of late recurrence in this subset of patients for whom long-term observation is recommended.

An extension of affected-pedigree-member analyses to triads of relatives

The affected third-degree relatives method ("cousins method"-CM) shares key features with the affected-sibling method, but it groups first cousins in triads, with the hope of requiring fewer individuals to be typed. The aim is to provide an efficient and computationally convenient method of genome screening, capitalizing on the vast number of highly informative markers mapped in recent years. The nonparametric CM statistic measures increased marker similarity, making no assumptions concerning how the disease is inherited; this can be advantageous when dealing with complex diseases for which the mode of inheritance is difficult to determine. This article presents a brief statistical development of the CM method and describes the results of applying the method to one replicate of the simulated extended family data set.

CpG oligonucleotides are potent adjuvants for the activation of autoreactive encephalitogenic T cells in vivo

The mechanism of action of microbial adjuvants in promoting the differentiation of autoimmune effector cells remains to be elucidated. We demonstrate that CpG-containing oligodeoxynucleotides (ODN) can completely substitute for heat-killed mycobacteria in the priming of encephalitogenic myelin-reactive T cells in vivo. The adjuvanticity of the CpG ODN was secondary to their direct ability to induce IL-12 or to act synergistically with endogenous IL-12 to promote Th1 differentiation and encephalitogenicity. T cells primed in the absence of CpG with Ag and IFA alone appeared to be in a transitional state and had not undergone differentiation along a conventional Th pathway. Unlike Th2 cells, they expressed low levels of the IL-12R beta 2 subunit and retained the ability to differentiate into encephalitogenic effectors when reactivated in vitro under Th1-polarizing conditions. These results support the use of CpG ODN as adjuvants but also suggest that they could potentially trigger autoimmune disease in a susceptible individual.