Fungal Depletion Bolsters Anti-Tumor Immune Response Elicited by Anti-PD1 Alone and in Combination with Radiation Therapy

PURPOSE/OBJECTIVE(S)

Pembrolizumab in combination with chemotherapy has become the standard of care treatment for both metastatic and early-stage triple negative breast cancer (TNBC). Clinical trials are currently underway investigating the use of pembrolizumab with radiation in the neoadjuvant setting in early TNBC. Several groups have described a link between the microbiome and the efficacy of chemotherapy and anti-PD1 immune checkpoint inhibitors (ICIs) in preclinical models. Recent work from our lab has shown that targeting commensal fungi in the microbiome enhances the radiation induced antitumor immune response. Therefore, we hypothesized that fungal depletion might positively impact anti-PD1 therapy and combination treatment with anti-PD1 and radiation therapy (RT).

MATERIALS/METHODS

This study utilized an orthotopic syngeneic breast tumor model in which the syngeneic cell line E0771 was injected into the mammary fat pad of female C57BL/6 mice. Tumor-bearing mice were then treated with and without the antifungal fluconazole, anti-PD1, and radiation (16 Gy single fraction) using the X-RAD SmART platform with CT guidance. Tumor volumes were compared using 2-way ANOVA and survival curves analyzed using log rank. In a separate set of experiments, tumor-infiltrating immune cells were isolated and analyzed by high-dimensional multiplex flow cytometry.

RESULTS

We found that fungal depletion with fluconazole prior to treatment with anti-PD1 reduced the tumor volume and significantly improved survival in comparison to those treated with anti-PD1 alone (P = 0.0016). To identify what changes in the tumor immune microenvironment is driving this increased anti-tumor response, we performed flow cytometry on immune cells isolated from the tumors. We found that the use of fluconazole prior to anti-PD1 treatment reduced the proportion of CD11b+F4/80+ tumor-associated macrophages (TAMs) (P = 0.01) and increased tumor infiltrating cytotoxic T cell population (P = 0.04) when compared with the use of anti-PD1 alone. We also evaluated the effect of fungal depletion on combination therapy with RT and anti-PD1. Strikingly, we found that mice depleted of fungi with fluconazole prior to radiation and anti-PD1 therapy, have decreased tumor burden and significantly increased survival when compared to their fungally-intact counterparts (P = 0.043).

CONCLUSION

Our data indicates that the depletion of the gut fungal populations induces an increased antitumor response following anti-PD1 alone and in combination with radiation. This increased antitumor immune response is associated with an increase in the cytotoxic CD8+ T cell compartment with concomitant decrease in immunosuppressive tumor associated macrophages.

Non-Redundant Mechanisms of Immune Resistance to Radiotherapy Converge on Innate Immunity

PURPOSE/OBJECTIVE(S)

Despite evidence of preclinical synergy between radiotherapy (RT) and immune checkpoint blockade (ICB), randomized trials of RT/ICB have demonstrated limited benefit in solid tumors. We performed single-cell RNA sequencing (scRNA-seq) and CITE-seq (cellular indexing of transcriptomes and epitopes) to address the discordance between preclinical and clinical data. We hypothesized that multiple orthogonal inhibitory immune pathways restrain the local and systemic efficacy of RT beyond T-cell oriented immune checkpoints.

MATERIALS/METHODS

We used the EO771 syngeneic murine model of breast cancer to characterize the immune tumor microenvironment following RT with or without ICB. RT (16 Gy x 1) was delivered using the X-RAD SmART platform with CT image guidance. Neutralizing antibodies (anti-PD-1/Ly6G/Gr-1/CD47) were delivered by intraperitoneal injections. scRNA-seq analysis were performed by Seurat and BBrowser (BioTuring).

RESULTS

We found that adaptive ICB (anti-PD-1) reprogrammed the immune response to RT by promoting an M1-like interferon-primed state (ISG15, CXCL10) in tumor associated macrophages (TAMs) and by increasing the late recruitment of intratumoral neutrophils. Given that neutrophils may drive resistance to RT in other models, we evaluated the effect of intratumoral neutrophil depletion using anti-Ly6G or anti-Gr-1 on the antitumor efficacy of RT/ICB. Both neutrophil depletion strategies led to enhanced tumor control and improved survival in advanced EO771 tumors compared to RT/ICB alone (P<0.001). In parallel to this approach, we found that TAMs upregulated several innate immune checkpoints including SIRPα in response to RT. Disruption of the SIRPα-CD47 interaction by anti-CD47 antibodies similarly enhanced the antitumor efficacy of RT/ICB by improving tumor control and survival (P<0.001). Using scRNA-seq and unbiased clustering, we found that anti-CD47 eliminated an entire cluster of chronically inflamed TAMs, characterized by pro-inflammatory markers (IL1A, NOS2) and chemokines (CCL3, CXCL1/2/3). Anti-CD47 also reduced intratumoral neutrophils by eliminating a cluster of pathologically activated neutrophils, termed myeloid-derived suppressor cells (PMN-MDSCs) that expressed several markers of ferroptosis (TFRC, PTGS2, SLC3A2). Consistent with the potent immunosuppressive capacity of PMN-MDSCs, we found that anti-CD47 increased tumor-infiltrating lymphocytes including central memory TCF7+ T cells and CD19+ B cells. Lastly, by inference and analysis of cell-cell communication (CellChat), we found that anti-CD47 strengthened the interactions between TAMs and CD8+ T cells compared to RT/ICB alone.

CONCLUSION

Our data collectively indicate that resistance to RT/ICB in the EO771 model Is driven by innate immune cells including neutrophils and chronically inflamed TAMs. Targeted disruption of the CD47-SIRPα axis is a promising approach to overcoming immune resistance by reprogramming TAMs and eliminating PMN-MDSCs.

Reshaping Macrophage Polarization Potential Enhances Antitumor Immune Response to Radiation Therapy

PURPOSE/OBJECTIVE(S)

Although radiation therapy (RT) remains a cornerstone in the treatment of breast cancer, many trials combining RT with immune checkpoint blockade (ICB) have failed to demonstrate benefit in solid tumors including breast cancer. Maximal efficacy of RT relies on the generation of antitumor immunity following treatment which largely consists of cytotoxic T cells and macrophages. Broad depletion of macrophages modestly enhances tumor responses to RT suggesting that they can shape RT-induced antitumor immunity. Although IL4 signaling through GATA-3 is known to polarize T cells into the protumor Th2 phenotype, such central drivers of macrophage polarization are not well established. Given that macrophages abundantly express IL4 receptor, we hypothesized that GATA-3 may direct the transition of macrophages to M2/alternative phase and that genetic ablation of GATA-3 in macrophages can enhance antitumor immunity by arresting macrophage transition to an M2-like pro-tumor state.

MATERIALS/METHODS

We generated a macrophage specific GATA-3 KO mouse model (mG3KO) driven by the LysM-Cre promoter. Using a syngeneic orthotopic murine model of breast cancer (EO771), we evaluated the differential effect of RT (16Gy x 1) in WT and mG3KO mice. Multiparametric flow cytometry was performed to investigate the immune changes within the tumor microenvironment on day 3, day 5 and day 10 after RT. T cell depletion was performed using antibodies to CD4 and CD8 by intraperitoneal injections to understand the role of adaptive immunity in the response to RT in WT and mG3KO mice.

RESULTS

We found that mG3KO mice bearing advanced EO771 tumors demonstrated significantly improved tumor regression compared to WT mice (p<0.001), which translated to increased overall survival. In vitro characterization of bone-marrow derived macrophages from mG3KO and WT mice suggest that macrophages with ablated GATA-3 expressed increased levels of iNOS and decreased levels of Arginase (Arg-1), consistent with an M1-like phenotype. Immune profiling of the tumors also revealed that mGATA-3 KO animals have significant enrichment of CD8+ T cells in the tumor milieu post RT and these CD8+ T cells express higher amounts of interferon gamma (p<0.001) and Granzyme B (p<0.0015) than their WT counterparts. Using neutralizing antibodies to deplete CD8+ T cells, we show that anti-tumor effects in the mG3KO mice were abolished, suggesting that mG3KO macrophages impact survival, at least, in part by enhancing cytotoxic CD8+T cells. Studies are currently ongoing to reveal the detailed mechanism of GATA-3 ablation in improving the efficacy of RT.

CONCLUSION

Our data indicates that GATA-3 is a central regulator of macrophage polarization in response to RT. Further, directed ablation of GATA-3 appears to drive macrophages towards an M1-like phenotype, which enhances T cell recruitment to irradiated tumors. These data suggest that the antitumor efficacy of RT can be prolonged by targeting GATA-3-dependent signaling within myeloid cells.

Feasibility and Acceptability of ChatGPT Generated Radiology Report Summaries for Cancer Patients

PURPOSE/OBJECTIVE(S)

Patients now have direct access to their diagnostic imaging reports. However, they can include complex terminology that can be difficult for patients to understand. ChatGPT (OpenAI, San Francisco, CA) is an artificial intelligence (AI) text-generating model that can simplify complex text and generate human-like responses. We assessed ChatGPT's ability to generate summarized MRI reports for patients with prostate cancer and evaluated physician satisfaction with providing patients with an AI-summarized report.

MATERIALS/METHODS

We used ChatGPT to summarize five prostate cancer MRI reports performed at our institution from 2021-2022. Using a standard prompt, we asked ChatGPT to summarize the full MRI reports into a patient letter at a 6th grade reading level. To account for variability in text output, we generated three different summarized reports per unique MRI report. Full MRI and summarized reports were assessed for readability using Flesch-Kincaid Grade Level (FK) score. Radiation oncologists at our institution were asked to evaluate the summarized reports with an anonymous questionnaire. Physicians were shown two full MRI reports and three summarized versions for each full report. For each summarized report, physicians were asked six questions assessing the following: factual correctness, ease of understanding, completeness, potential for harm, overall quality, and likelihood they would send the report to a patient. Qualitative responses were given on a 1-5 Likert-type scale.

RESULTS

A total of 15 summarized reports were generated from five full MRI reports using ChatGPT. The median FK score for the full MRI reports and summarized reports was 9.6 vs. 5.0, (p<0.05), respectively. 12 radiation oncologists responded to our questionnaire with experience levels of: resident (25%), attending <5 years (33%), attending 5-10 years (17%), and attending >10 years (25%). The mean [SD] rating across all six summarized reports for each of the questions were: factual correctness (4.0 [0.6], understanding 4.0 [0.7]), completeness (4.1 [0.5]), potential for harm (3.5 [0.9]), overall quality (3.4 [0.9]), and likelihood to send to patient (3.1 [1.1]). 89%, 78%, and 93% of respondents answered agree or strongly agree for correctness, ease of understanding, and completeness of the summarized reports. 51%, 53%, and 46% of respondents answered agree or strongly agree for potential for harm, overall quality, and likelihood to send to patient.

CONCLUSION

ChatGPT was able to summarize prostate MRI reports at a reading level appropriate for patients. Physicians were likely to be satisfied with the summarized reports with respect to factual correctness, ease of understanding, and completeness. They were less likely to be satisfied with respect to potential for harm, overall quality, and likelihood to send to patients. Further research is needed to optimize ChatGPT's ability to summarize radiology reports for patients and understand what factors influence physician trust in AI-summarized reports.

Homologous peptides derived from influenza A, B and C viruses induce variable CD8+ T cell responses with cross-reactive potential

Objective

Influenza A, B and C viruses (IAV, IBV and ICV, respectively) circulate globally, infecting humans and causing widespread morbidity and mortality. Here, we investigate the T cell response towards an immunodominant IAV epitope, NP_265‐273, and its IBV and ICV homologues, presented by HLA‐A*03:01 molecule expressed in ~ 4% of the global population (~ 300 million people).

Methods

We assessed the magnitude (tetramer staining) and quality of the CD8⁺ T cell response (intracellular cytokine staining) towards NP_265‐IAV and described the T cell receptor (TCR) repertoire used to recognise this immunodominant epitope. We next assessed the immunogenicity of NP_265‐IAV homologue peptides from IBV and ICV and the ability of CD8⁺ T cells to cross‐react towards these homologous peptides. Furthermore, we determined the structures of NP_265‐IAV and NP_323‐IBV peptides in complex with HLA‐A*03:01 by X‐ray crystallography.

Results

Our study provides a detailed characterisation of the CD8⁺ T cell response towards NP_265‐IAV and its IBV and ICV homologues. The data revealed a diverse repertoire for NP_265‐IAV that is associated with superior anti‐viral protection. Evidence of cross‐reactivity between the three different influenza virus strain‐derived epitopes was observed, indicating the discovery of a potential vaccination target that is broad enough to cover all three influenza strains.

Conclusion

We show that while there is a potential to cross‐protect against distinct influenza virus lineages, the T cell response was stronger against the IAV peptide than IBV or ICV, which is an important consideration when choosing targets for future vaccine design.

Mathematical models to describe the growth curves of Vietnamese Ri chicken

Ri chicken is the most popular backyard chicken breed in Vietnam, but little is known about the growth curve of this breed. This study compared the performances of models with three parameters (Gompertz, Brody, and Logistic) and models containing four parameters (Richards, Bridges, and Janoschek) for describing the growth of Ri chicken. The bodyweight of Ri chicken was recorded weekly from week 1 to week 19. Growth models were fitted using minpack.lm package in R software and Akaike's information criterion (AIC), Bayesian information criterion (BIC), and root mean square error (RMSE) were used for model comparison. Based on these criteria, the models having four parameters showed better performance than the ones with three parameters, and the Richards model was the best one for males and females. The lowest and highest value of asymmetric weights (α) were obtained by Bridges and Brody models for each of sexes, respectively. Age and weight estimated by the Richard model were 8.46 and 7.51 weeks and 696.88 and 487.58 g for males and for females, respectively. Differences in the growth curves were observed between males and female chicken. Overall, the results suggested using the Richards model for describing the growth curve of Ri chickens. Further studies on the genetics and genomics of the obtained growth parameters are required before using them for the genetic improvement of Ri chickens.

Molecular Basis of a Dominant SARS-CoV-2 Spike-Derived Epitope Presented by HLA-A*02:01 Recognised by a Public TCR

The data currently available on how the immune system recognises the SARS-CoV-2 virus is growing rapidly. While there are structures of some SARS-CoV-2 proteins in complex with antibodies, which helps us understand how the immune system is able to recognise this new virus; however, we lack data on how T cells are able to recognise this virus. T cells, especially the cytotoxic CD8+ T cells, are critical for viral recognition and clearance. Here we report the X-ray crystallography structure of a T cell receptor, shared among unrelated individuals (public TCR) in complex with a dominant spike-derived CD8+ T cell epitope (YLQ peptide). We show that YLQ activates a polyfunctional CD8+ T cell response in COVID-19 recovered patients. We detail the molecular basis for the shared TCR gene usage observed in HLA-A*02:01+ individuals, providing an understanding of TCR recognition towards a SARS-CoV-2 epitope. Interestingly, the YLQ peptide conformation did not change upon TCR binding, facilitating the high-affinity interaction observed.

Biogeochemical functioning of an urbanized tropical estuary: Implementing the generic C-GEM (reactive transport) model

Estuaries are amongst the most productive ecosystems of the land ocean continuum, but they are also under high anthropic pressures due to coastal urbanization. Too sparse observations have hindered the understanding of complex interactions between water quality and estuarine hydrodynamics and biogeochemical transformations. Until now, estuarine modelling studies have mainly focused on temperate estuarine systems in industrialized countries. This study investigates the responses of a tropical estuary to pollution load from a megacity (Ho Chi Minh City, Southern Vietnam) by applying a one-dimensional, biogeochemical estuarine model (C-GEM). The Saigon River Estuary flows through the megacity of Ho Chi Minh (HCMC) and is subject to episodic hypoxia events due to wastewater inputs from urban discharges. Good agreements are found between simulation outputs and observations for tidal propagation, salinity, total suspended sediment, and water quality variables in dry season in Saigon River Estuary. C-GEM reproduces the increases in ammonium, total organic carbon, phytoplankton and dissolved oxygen depletion in the urban section of the Saigon River as an impact of untreated wastewaters from HCMC. The steady-state version of C-GEM also reveals the formation of a pollutant cloud (30-km stretch) resulting from the combined effects of tidal fluctuation and low flushing capacity during the dry season. Furthermore, the quantification of the reaction fluxes simulated by the model demonstrates that nitrification is the main process removing NH₄⁺ from the Saigon River. For the first time in such a type of environment, our study demonstrates the effectiveness of C-GEM at unraveling the complex interplay between biogeochemical reactions and transport in a tropical estuary with a minimized data requirement. This is significant for tropical estuaries in developing countries, where intensive monitoring programs are rare and have thus been rarely the object of modelling investigations.

CD8+ T cells specific for an immunodominant SARS-CoV-2 nucleocapsid epitope cross-react with selective seasonal coronaviruses

Efforts are being made worldwide to understand the immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for the coronavirus disease 2019 (COVID-19) pandemic, including the impact of T cell immunity and cross-recognition with seasonal coronaviruses. Screening of SARS-CoV-2 peptide pools revealed that the nucleocapsid (N) protein induced an immunodominant response in HLA-B7+ COVID-19-recovered individuals that was also detectable in unexposed donors. A single N-encoded epitope that was highly conserved across circulating coronaviruses drove this immunodominant response. In vitro peptide stimulation and crystal structure analyses revealed T cell-mediated cross-reactivity toward circulating OC43 and HKU-1 betacoronaviruses but not 229E or NL63 alphacoronaviruses because of different peptide conformations. T cell receptor (TCR) sequencing indicated that cross-reactivity was driven by private TCR repertoires with a bias for TRBV27 and a long CDR3β loop. Our findings demonstrate the basis of selective T cell cross-reactivity for an immunodominant SARS-CoV-2 epitope and its homologs from seasonal coronaviruses, suggesting long-lasting protective immunity.

Pre-existing cellular immunity to SARS-CoV-2 through an immunodominant epitope

Significant efforts are being made worldwide to understand the immune response to SARS-CoV-2, responsible for the COVID-19 pandemic, including the role of preexisting T cell immunity. Understanding the mechanisms that promote crossrecognition by T cells induced by seasonal coronaviruses will be critical for future predictions on the role of pre-existing immunity in protection against severe disease. We demonstrate that the SARS-CoV-2 nucleocapsid (N) protein induces an immunodominant response in HLA-B7+ COVID-19-recovered individuals that is also readily detectable in unexposed donors. This immunodominant response is driven by a single N-encoded epitope that displays a high degree of conservation with the homologous region in circulating coronaviruses. We show that T cell-mediated crossreactivity can be detected towards the circulating OC43/HKU-1 coronaviruses, but not the 229E or NL63 coronaviruses, due to different peptide conformations. This cross-reactivity is driven by private T cell receptor repertoires with a bias for TRBV27 and a long CDR3b loop in unexposed and COVID-19-recovered individuals. Together, our findings demonstrate the basis of pre-existing immunity to a conserved and highly immunogenic SARS-CoV-2 epitope driven by cross-reactive memory T cells, suggesting long-lived protective immunity.

The presentation of SARS-CoV-2 peptides by the common HLA-A∗02:01 molecule

CD8+ T cells are crucial for anti-viral immunity; however, understanding T cell responses requires the identification of epitopes presented by human leukocyte antigens (HLA). To date, few SARS-CoV-2-specific CD8+ T cell epitopes have been described. Internal viral proteins are typically more conserved than surface proteins and are often the target of CD8+ T cells. Therefore, we have characterized eight peptides derived from the internal SARS-CoV-2 nucleocapsid protein predicted to bind HLA-A^∗02:01, the most common HLA molecule in the global population. We determined not all peptides could form a complex with HLA-A^∗02:01, and the six crystal structures determined revealed that some peptides adopted a mobile conformation. We therefore provide a molecular understanding of SARS-CoV-2 CD8+ T cell epitopes. Furthermore, we show that there is limited pre-existing CD8+ T cell response toward these epitopes in unexposed individuals. Together, these data show that SARS-CoV-2 nucleocapsid might not contain potent epitopes restricted to HLA-A^∗02:01.

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HLA-A∗02:01 individuals have limited pre-existing immunity to SARS-CoV-2 nucleocapsid

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High-resolution crystal structures of HLA-A∗02:01 presenting SARS-CoV-2 peptides

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Structural analysis of pHLA shows stability influences peptide immunogenicity

Overlapping Peptides Elicit Distinct CD8+ T Cell Responses following Influenza A Virus Infection

The presentation of pathogen-derived peptides on MHC class I molecules is essential for the initiation of adaptive CD8⁺ T cell immunity, which in turn is critical for effective control of many significant human infections. The identification of immunogenic pathogen-derived epitopes and a detailed understanding of how they are recognized by TCRs is essential for the design of effective T cell-based vaccines. In this study, we have characterized the T cell recognition and immune responses in mice to two naturally presented influenza A virus-derived peptides previously identified from virally infected cells via mass spectrometry. These neuraminidase-derived peptides, NA_181-190 (SGPDNGAVAV) and NA_181-191 (SGPDNGAVAVL), are completely overlapping with the exception of a 1 aa extension at the C terminus of the longer peptide. This minor peptidic difference results in the induction of two completely independent and non-cross-reactive T cell populations that show distinct functional characteristics after influenza A virus infection of B6 mice. We show that the unique TCR reactivity to the overlapping peptides is present in the naive repertoire prior to immune expansion in B6 mice. Moreover, we provide a structural explanation underlying the distinct CD8⁺ T cell reactivities, which reinforces the concept that peptide length is a key determinant of Ag specificity in CD8⁺ T cell responses.

CD4+ T cell recognition of haemagglutinin epitope across Influenza strains

In 2018 the World Health Organisation listed influenza pandemics as one of the top threats to global health. Influenza pandemics occur as a result of the emergence of antigenically distinct strains, which arise due to genomic re-assortment or through the acquisition of mutations. The resulting strains have different antigenic make-ups and implicate the ability of the immune system to respond quickly following infection. Particular HLA class II allomorphs including HLA-DRB1*07:01 have been linked with the occurrence of severe influenza infections and non-response to the influenza vaccine. However, other allomorphs such as HLA-DRB1*11:01 have been shown to be protective in viral diseases such as HIV and HCV, and might be important for influenza infection. The mechanism surrounding these associations of influenza infection and HLA class II molecules expression is unclear. As some individuals expressing particular HLA allomorphs are at a greater risk of developing severe influenza infection, further investigation into the mechanism of this association is warranted. Through stimulating T cells from donors expressing HLA-DRB1*11:01 or HLA-DRB1*07:01 with an influenza epitope (HA) derived from pandemic and epidemic influenza strains, we determined the level of cross-reactivity, phenotype and polyfunctionality of the responding CD4+ specific T cells. We have compared different allomorphs and provide the first insight into the molecular basis of influenza epitope recognition by different HLA class II allomorphs, and its functional impact.

The unconventional role of HLA-E: The road less traveled

Histocompatibility Leukocyte Antigens, or HLAs, are one of the most polymorphic molecules in humans. This high degree of polymorphism endows HLA molecules with the ability to present a vast array of peptides, an essential trait for responding to ever-evolving pathogens. Unlike classical HLA molecules (HLA-Ia), some non-classical HLA-Ib molecules, including HLA-E, are almost monomorphic. Several studies show HLA-E can present self-peptides originating from the leader sequence of other HLA molecules, which signals to our immune system that the cell is healthy. Therefore, it was traditionally thought that the chief role of HLA-E in the body was in immune surveillance. However, there is emerging evidence that HLA-E is also able to present pathogen-derived peptides to the adaptive immune system, namely T cells, in a manner that is similar to classical HLA-Ia molecules. Here we describe the early findings of this less conventional role of HLA-E in the adaptive immune system and its importance for immunity.

Tumor cell capture from blood by flowing across antibody-coated surfaces

The load of circulating tumor cells (CTC) is related to poor outcomes in cancer patients. A sufficient number of these cells would enable a full characterization of the cancer. An approach to probe larger blood volumes, allowing for the detection of more of these very rare CTC, is the use of leukapheresis. Currently available techniques allow only the analysis of a small portion of leukapheresis products. Here, we present a method that uses flow rather than static conditions which allows processing of larger volumes. We evaluated the conditions needed to isolate tumor cells from blood while passing antibody coated surfaces. Results show that our set-up efficiently captures cancer cells from whole blood. Results show that the optimal velocity at which cells are captured from blood is 0.6 mm s-1. Also, it can be concluded that the VU1D9 antibody targeting the EpCAM antigen has very high capture efficiency. When using an antibody that does not capture 100% of all cells, combining multiple antibodies on the capture surface is very beneficial leading to an increase in cell capture and is therefore worthwhile considering in any cancer cell capture methodology.

Intraoperative serum lactate is not a predictor of survival after glioblastoma surgery

BACKGROUND

Cancer cells can produce lactate in high concentrations. Two previous studies examined the clinical relevance of serum lactate as a biomarker in patients with brain tumors. Patients with high-grade tumors have higher serum concentrations of lactate than those with low-grade tumors. We hypothesized that serum lactic could be used of biomarker to predictor of survival in patients with glioblastoma (GB).

METHODS

This was a retrospective study. Demographic, lactate concentrations and imaging data from 275 adult patients with primary GB was included in the analysis. The progression free survival (PFS) and overall survival (OS) rates were compared in patients who had above and below the median concentrations of lactate. We also investigated the correlation between lactate concentrations and tumor volume. Multivariate analyses were conducted to test the association lactate, tumor volume and demographic variables with PFS and OS.

RESULTS

The median serum concentration of lactate was 2.3mmol/L. A weak correlation was found between lactate concentrations and tumor volume. Kaplan-Meier curves demonstrated similar survival in patients with higher or lower than 2.3mmol/L of lactate. The multivariate analysis indicated that the intraoperative levels of lactate were not independently associated with changes in survival. On another hand, a preoperative T1 volume was an independent predictor PFS (HR 95%CI: 1.41, 1.02-1.82, p=0.006) and OS (HR 95%CI: 1.47, 1.11-1.96, p=0.006).

CONCLUSION

This retrospective study suggests that the serum concentrations of lactate cannot be used as a biomarker to predict survival after GB surgery. To date, there are no clinically available serum biomarkers to determine prognosis in patients with high-grade gliomas. These tumors may produce high levels of lactic acid. We hypothesized that serum lactic could be used of biomarker to predictor of survival in patients with glioblastoma (GB). In this study, we collected perioperative and survival data from 275 adult patients with primary high-grade gliomas to determine whether intraoperative serum acid lactic concentrations can serve as a marker of prognosis. The median serum concentration of lactate was 2.3mmol/L. Our analysis indicated the intraoperative levels of lactate were not independently associated with changes in survival. This retrospective study suggests that the serum concentrations of lactate cannot be used as a biomarker to predict survival after GB surgery.

Abstract P1-08-11: Association of variants in candidate genes on lipid profiles in women with early breast cancer on adjuvant aromatase inhibitor therapy

Background

Aromatase inhibitors (AI) can exert unfavorable effects on lipid profiles, but previous studies have reported inconsistent results. Given the intricate biological relationship between estrogen and lipid profiles, these mixed results may be explained in part by variation in genes encoding proteins involved in the drug's target and in estrogen metabolism and signaling. The purpose of this study was to investigate associations of single-nucleotide polymorphisms (SNP) in candidate genes with AI-mediated changes in lipid profiles.

Methods

We completed a prospective multicenter randomized observational open-label study to test the association of SNPs in candidate genes on biomarkers of estrogenic and anti-estrogenic activity in post-menopausal women with early breast cancer who were recommended adjuvant AI therapy. Eligible women were randomly assigned to exemestane or letrozole, and were followed for 2 years. We genotyped 137 SNPs from germ line DNA in the following candidate genes: ARVCF, COMT, CYP19A1, ESR1, ESR2, PGR, EP300, EZH2, NCOA1-3, NCOR1-2, NRIP, and PELP1. Lipid profiles including total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglycerides (TG) were measured at baseline and 3 months after initiating AI. We conducted genetic association data analysis and multivariate linear regressions to analyze the genetic effects using dominant, recessive, and additive models. Multivariate analysis included age, body mass index, prior hormone replacement therapy, and prior tamoxifen. To adjust for multiple comparisons, only SNPs with a p&lt;0.0003 were considered significant.

Results

We enrolled 502 women in to the study, but for this analysis we excluded women who did not have genetic data (n = 33), had incomplete data (n = 23), discontinued or crossed over AI therapy (n = 48), women not fasting at both time points (n = 89), or those on lipid-lowering medications (n = 162). A total of 200 women were evaluable (letrozole 107, exemestane 93). Lipid profiles in all patients (n = 200) at baseline and 3 months after initiating AI, respectively, were as follows: TC 204.9 and 203.3 (unchanged, p = 0.43); HDL 61.3 and 56.8 (decreased, p = 6.3E-10); LDL 122.2 and 124.6 (unchanged, p = 0.22); and TG 107.1 and 103.6 (unchanged, p = 0.26). Genetic association and multivariate analysis revealed that SNPs in ESR1 and NCOR1 are significantly associated with additional changes in lipid parameters as summarized in Table 1.

Table 1.Significant findings of multivariate linear regressions analyzing genetic associations between candidate gene SNPs and lipid profiles of AI-treated women.CohortNumberSNP (gene)Minor Allele FrequencyLipid ParameterModel UsedMean Absolute Change (mg/dL)P-valueAll patients184rs9340958 (ESR1)0.07TCRecessive-2.250.0003Letrozole96rs9340958 (ESR1)0.07TCRecessive5.280.00009 101rs3020368 (ESR1)0.09TCRecessive6.350.00007Exemestane93rs3798758 (ESR1)0.03HDLDominant, additive-7.970.00001 88rs926848 (ESR1)0.03HDLDominant, additive-7.970.00002 93rs61753150 (NCOR1)0.01TGDominant, additive-11.630.00003

Conclusions

Variants in genes involved in estrogen metabolism and signaling are associated with changes in lipid profiles in AI-treated women and should be validated in other studies.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-08-11.

Genome-wide discovery of genetic variants affecting tamoxifen sensitivity and their clinical and functional validation

BACKGROUND

Beyond estrogen receptor (ER), there are no validated predictors for tamoxifen (TAM) efficacy and toxicity. We utilized a genome-wide cell-based model to comprehensively evaluate genetic variants for their contribution to cellular sensitivity to TAM.

DESIGN

Our discovery model incorporates multidimensional datasets, including genome-wide genotype, gene expression, and endoxifen-induced cellular growth inhibition in the International HapMap lymphoblastoid cell lines (LCLs). Genome-wide findings were further evaluated in NCI60 cancer cell lines. Gene knock-down experiments were performed in four breast cancer cell lines. Genetic variants identified in the cell-based model were examined in 245 Caucasian breast cancer patients who underwent TAM treatment.

RESULTS

We identified seven novel single-nucleotide polymorphisms (SNPs) associated with endoxifen sensitivity through the expression of 10 genes using the genome-wide integrative analysis. All 10 genes identified in LCLs were associated with TAM sensitivity in NCI60 cancer cell lines, including USP7. USP7 knock-down resulted in increasing resistance to TAM in four breast cancer cell lines tested, which is consistent with the finding in LCLs and in the NCI60 cells. Furthermore, we identified SNPs that were associated with TAM-induced toxicities in breast cancer patients, after adjusting for other clinical factors.

CONCLUSION

Our work demonstrates the utility of a cell-based model in genome-wide identification of pharmacogenomic markers.

A SNP in steroid receptor coactivator-1 disrupts a GSK3β phosphorylation site and is associated with altered tamoxifen response in bone

The coregulator steroid receptor coactivator (SRC)-1 increases transcriptional activity of the estrogen receptor (ER) in a number of tissues including bone. Mice deficient in SRC-1 are osteopenic and display skeletal resistance to estrogen treatment. SRC-1 is also known to modulate effects of selective ER modulators like tamoxifen. We hypothesized that single nucleotide polymorphisms (SNP) in SRC-1 may impact estrogen and/or tamoxifen action. Because the only nonsynonymous SNP in SRC-1 (rs1804645; P1272S) is located in an activation domain, it was examined for effects on estrogen and tamoxifen action. SRC-1 P1272S showed a decreased ability to coactivate ER compared with wild-type SRC-1 in multiple cell lines. Paradoxically, SRC-1 P1272S had an increased protein half-life. The Pro to Ser change disrupts a putative glycogen synthase 3 (GSK3)β phosphorylation site that was confirmed by in vitro kinase assays. Finally, knockdown of GSK3β increased SRC-1 protein levels, mimicking the loss of phosphorylation at P1272S. These findings are similar to the GSK3β-mediated phospho-ubiquitin clock previously described for the related coregulator SRC-3. To assess the potential clinical significance of this SNP, we examined whether there was an association between SRC-1 P1272S and selective ER modulators response in bone. SRC-1 P1272S was associated with a decrease in hip and lumbar bone mineral density in women receiving tamoxifen treatment, supporting our in vitro findings for decreased ER coactivation. In summary, we have identified a functional genetic variant of SRC-1 with decreased activity, resulting, at least in part, from the loss of a GSK3β phosphorylation site, which was also associated with decreased bone mineral density in tamoxifen-treated women.

Plasma letrozole concentrations in postmenopausal women with breast cancer are associated with CYP2A6 genetic variants, body mass index, and age

The associations between plasma letrozole concentrations and CYP2A6 and CYP3A5 genetic variants were tested in the Exemestane and Letrozole Pharmacogenomics (ELPH) trial. ELPH is a multicenter, open-label prospective clinical trial in women randomly assigned (n≈250 in each arm) to receive 2 years of treatment with either oral letrozole (2.5 mg/day) or oral exemestane (25 mg/day). CYP2A6 and CYP3A showed effects on letrozole metabolism in vitro. DNA samples were genotyped for variants in the CYP2A6 and CYP3A5 genes. Plasma letrozole concentrations showed high interpatient variability (>10-fold) and were associated significantly with CYP2A6 genotypes (P<0.0001), body mass index (BMI) (P<0.0001), and age (P=0.0035). However, CYP3A5 genotypes showed no association with plasma letrozole concentrations. These data suggest that CYP2A6 is the principal clearance mechanism for letrozole in vivo. CYP2A6 metabolic status, along with BMI and age, may serve as a biomarker of the efficacy of letrozole treatment or a predictor of adverse effects.

Cytochrome P450 2D6 activity predicts discontinuation of tamoxifen therapy in breast cancer patients

The selective estrogen receptor modulator tamoxifen is routinely used for treatment and prevention of estrogen-receptor-positive breast cancer. Studies of tamoxifen adherence suggest that over half of patients discontinue treatment before the recommended 5 years. We hypothesized that polymorphisms in CYP2D6, the enzyme responsible for tamoxifen activation, predict for tamoxifen discontinuation. Tamoxifen-treated women (n=297) were genotyped for CYP2D6 variants and assigned a 'score' based on predicted allele activities from 0 (no activity) to 2 (high activity). Correlation between CYP2D6 score and discontinuation rates at 4 months was tested. We observed a strong nonlinear correlation between higher CYP2D6 score and increased rates of discontinuation (r(2)=0.935, P=0.018). These data suggest that presence of active CYP2D6 alleles may predict for higher likelihood of tamoxifen discontinuation. Therefore, patients who may be most likely to benefit from tamoxifen may paradoxically be most likely to discontinue treatment prematurely.

Estrogen receptor genotypes, menopausal status, and the lipid effects of tamoxifen

Tamoxifen induces important changes in serum lipid profiles in some women; however, little information is available to predict which women will experience improved lipid profiles during tamoxifen therapy. As part of a multicenter prospective observational trial in 176 breast cancer patients, we tested the hypothesis that tamoxifen-induced lipid changes were associated with genetic variants in candidate target genes (CYP2D6, ESR1, and ESR2). Tamoxifen lowered low-density lipoprotein cholesterol (P<0.0001) by 23.5 mg/dl (13.5-33.5 mg/dl) and increased triglycerides (P=0.006). In postmenopausal women, the ESR1-XbaI and ESR2-02 genotypes were associated with tamoxifen-induced changes in total cholesterol (P=0.03; GG vs GA/AA) and triglycerides (P=0.01; gene-dose effect), respectively. In premenopausal women, the ESR1-XbaI genotypes were associated with tamoxifen-induced changes in triglycerides (P=0.002; gene-dose effect) and high-density lipoprotein (P=0.004; gene-dose effect). Our results suggest that estrogen receptor genotyping may be useful in predicting which women would benefit more from tamoxifen.

The pharmacogenetics research network: from SNP discovery to clinical drug response

The NIH Pharmacogenetics Research Network (PGRN) is a collaborative group of investigators with a wide range of research interests, but all attempting to correlate drug response with genetic variation. Several research groups concentrate on drugs used to treat specific medical disorders (asthma, depression, cardiovascular disease, addiction of nicotine, and cancer), whereas others are focused on specific groups of proteins that interact with drugs (membrane transporters and phase II drug-metabolizing enzymes). The diverse scientific information is stored and annotated in a publicly accessible knowledge base, the Pharmacogenetics and Pharmacogenomics Knowledge base (PharmGKB). This report highlights selected achievements and scientific approaches as well as hypotheses about future directions of each of the groups within the PGRN. Seven major topics are included: informatics (PharmGKB), cardiovascular, pulmonary, addiction, cancer, transport, and metabolism.

Combined mitochondrial and nuclear sequences support the monophyly of forcipulatacean sea stars

Previous molecular phylogenetic analyses of forcipulatacean sea stars (Echinodermata: Asteroidea) have reconstructed a non-monophyletic order Forcipulatida, provided that two or more forcipulate families are included. This result could mean that one or more assumptions of the reconstruction method was violated, or else the traditional classification could be erroneous. The present molecular phylogenetic analysis included 12 non-forcipulatacean and 39 forcipulatacean sea stars, with multiple representatives of all but one of the forcipulate families and/or subfamilies. Bayesian analysis of approximately 4.2kb of sequence data representing seven partitions (nuclear 18S rRNA and 28S rRNA, mitochondrial 12S rRNA, 16S rRNA, 5 tRNAs and cytochrome oxidase I with first and second codon positions analyzed separately from third codon positions) recovered a consensus tree with three well-supported clades (78%-100% bootstrap support) that corresponded at least approximately to traditional taxonomic ranks: the superorder Forcipulatacea (Forcipulatida + Brisingida) + Pteraster, the Brisingida/Brisingidae and Asteriidae + Rathbunaster + Pycnopodia. When a molecular clock was enforced, the partitioned Bayesian analysis recovered the traditional Forcipulatacea. Five of six genera represented by two or more species were monophyletic with 100% bootstrap support. Most of the traditional subfamilial and familial groupings within the Forcipulatida were either unresolved or non-monophyletic. The separate partitions differed considerably in estimates of model parameters, mainly between nuclear sequences (with high GC content, low rates of sequence substitution and high transition/transversion rate ratios) and mitochondrial sequences.

Metal-catalyzed oxidation induces carbonylation of peroxisomal proteins and loss of enzymatic activities

Peroxisomes are involved in oxidative metabolic reactions and have the capacity to generate large amounts of reactive oxygen species that could damage biomolecules including their own resident proteins. The purpose of this study was to determine whether peroxisomal proteins are susceptible to oxidation and whether oxidative damage affects their enzymatic activity. Peroxisomal proteins were subjected to metal-catalyzed oxidation (MCO) with CuCl(2)/ascorbate and derivatized with 2,4-dinitrophenylhydrazine which allowed for spectrophotometric quantification of carbonylation. Immunochemical detection of carbonylated peroxisomal proteins, resolved by gel electrophoresis and detected with anti-DNP antibodies, revealed five oxidatively modified proteins with the following molecular weights: 80, 66, 62, 55, and 50 kDa. The proteins at 66, 62, and 55 kDa were identified as malate synthase (MS), isocitrate lyase, and catalase (CAT), respectively. MS and CAT were estimated to contain 2-3 mol of carbonyl/mol of protein as a result of MCO. Enzymatic assays revealed varying degrees of activity loss. Isocitrate lyase and malate synthase showed significant loss of activity while catalase and malate dehydrogenase were less inhibited by carbonylation. Our findings show that peroxisomal proteins are vulnerable to MCO damage and thus may also be affected by in vivo exposure to reactive oxygen species.

Cytotoxic constituents from Plumbago zeylanica

The bioassay-guided fractionation of the dichloromethane extract of aerial parts of Plumbago zeylanica led to the isolation of beta-sitosterol, beta-sitosteryl-3beta-glucopyranoside, beta-sitosteryl-3beta-glucopyranoside-6'-O-palmitate (1), lupenone, lupeol acetate, plumbagin and trilinolein. Compound 1 showed cytotoxic activity against MCF7 and Bowes cancer cell lines (IC50 113 microM and 152 microM, respectively), beta-sitosterol inhibited Bowes cell growth (IC50 36.5 microM) and plumbagin was cytotoxic against MCF7 and Bowes cells (IC50 1.28 microM and 1.39 microM, respectively).

Determination of levofloxacin in plasma, bronchoalveolar lavage and bone tissues by high-performance liquid chromatography with ultraviolet detection using a fully automated extraction method

The aim of this study was to develop a specific and sensitive high-performance liquid chromatographic (HPLC) assay for the determination of levofloxacin in human plasma, bronchoalveolar lavage and bone tissues. The sample extraction was based on a fully automated liquid-solid extraction with an OASIS cartridge. The method used ultraviolet detection set at a wavelength of 299 nm and a separation with a Supelcosil ABZ+ column. The assay has been found linear over the concentration range 0.25-25 microg/ml for levofloxacin in plasma, 1-6 microg/ml in bronchoalveolar lavage and 0.5-10 microg/g for bone tissues and it provided good validation data for accuracy and precision. The assay will be applied to determine the penetration of levofloxacin in human bronchoalveolar lavage (BAL) and bone tissues during pharmacokinetic steady state.

Longer duration of predialysis nephrological care is associated with improved long-term survival of dialysis patients

BACKGROUND

Late nephrological referral of chronic renal failure patients has been shown to be associated with high morbidity and short-term mortality on dialysis. However, the impact of predialysis nephrological care duration (PNCD) on the long-term survival of dialysis patients had not been evaluated.

METHODS

We studied data from all 1057 consecutive patients who started dialysis treatment at the Necker Hospital from 1989 to 1998 (mean age at start of dialysis 53.8+/-17.2 years (range 18-91 years), excluding from analysis patients who presented with acute renal failure (n=60) or advanced malignancy (n=35). We evaluated the effects of PNCD and clinical risk factors on all-cause mortality after long-term follow-up on dialysis.

RESULTS

Among the 1057 patients analysed (13.2% diabetics), PNCD was <6 months in 258 patients, 6-35 months in 267 patients, 36-71 months in 227 patients and >or=72 months in 307 patients. Cardiovascular (CV) morbidity, namely a history of myocardial or cerebral infarction, peripheral arteriopathy, and/or cardiac failure, before starting dialysis was 39.6% and 37.4%, respectively, in patients followed for <6 months or 6-35 months, compared with 24.4% in those followed for 36-71 months and 19.9% in those followed for >or=72 months (P<0.001). Five-year survival was significantly lower in patients with a PNCD of <6 months (59+/-4.1%) than for 36-71 months or >or=72 months (77.1+/-3.7 and 73.3+/-3.6%, respectively, P<0.001), but similar to those followed for 6-35 months (65.3+/-3.9%, NS). By Cox proportional hazard analysis, PNCD <6 months, age, diabetes and prior CV disease were independent predictive factors of all-cause death on dialysis.

CONCLUSIONS

This study provides suggestive evidence that longer duration of regular nephrological care in the predialysis period, at least for several years prior to the start of dialysis, is associated with a better long-term survival on dialysis. Such data strongly support the argument for early referral and regular nephrological care of chronic renal failure patients.

Advantages of short-lived positron-emitting radioisotopes for intracoronary radiation therapy with liquid-filled balloons to prevent restenosis

Balloon catheters filled with liquid radioisotopes provide excellent dose homogeneity for intracoronary radiation therapy but are associated with risk for rupture or leakage. We hypothesized that the safety of liquid-filled balloons may be improved once positron emitters with half-lives below 2 h are used instead of the high-energy beta-emitters 166Ho, 186Re, or 188Re, all of which have a longer half-life of at least 17 h.

METHODS

To support this concept, the suitability of 18F (half-life, 109.8 min), 68Ga (half-life, 67.6 min), 11C (half-life, 20.4 min), 13N (half-life, 9.97 min), and 15O (half-life, 2.04 min) for intracoronary radiation therapy was evaluated. Potential tissue penetration of positron radiation was assessed in a series of phantom experiments using Gafchromic film. Antiproliferative efficacy of positrons emitted by 68Ga was investigated in vitro using cultured bovine aortic smooth muscle cells (BASMCs), and was compared with gamma-radiation emitted by 137Cs. To characterize the remaining risk, we estimated radiotoxicity after accidental intravascular balloon rupture on the basis of tabulated isotope-specific doses (ICRP 53) and compared these values with 188Re.

RESULTS

Half-dose depth of tissue penetration measured in phantom experiments was 0.29 mm for 18F, 0.42 mm for 11C, 0.54 mm for 13N, 0.79 mm for 15O, and 0.9 mm for 68Ga. Irradiation of cultured BASMCs with positron radiation (68Ga) induced dose-dependent inhibition of proliferation with complete proliferative arrest at doses exceeding 6 Gy. ED(50) and ED(80) were 2.5 +/- 0.4 Gy (mean +/- SD) and 4.4 +/- 0.8 Gy, respectively. Antiproliferative efficacy was equal to that of the 662-keV gamma-radiation emitted by 137Cs (ED(50), 3.8 +/- 0.2 Gy; ED(80), 8.0 +/- 0.3 Gy). Estimates made for patient whole-body and organ doses were generally below 50 mSv/1.85 GBq for all investigated positron emitters. The same dose estimates for 188Re were 6-20 fold higher.

CONCLUSION

Among the studied radioisotopes, 68Ga is the most attractive source for liquid-filled balloons because of its convenient half-life, sufficient positron energy (2.92 MeV), documented antiproliferative efficacy, and uncomplicated availability from a radioisotope generator. The safety profile for 68Ga is significantly better than that of 188Re, which suggests this radioisotope should be evaluated further in preclinical studies.

Liquid-filled balloon brachytherapy using (68)Ga is effective and safe because of the short 68-minute half-life: results of a feasibility study in the porcine coronary overstretch model

BACKGROUND

Liquid-filled balloons for coronary brachytherapy provide significant advantages over solid sources in dose homogeneity but carry the risk of life-threatening radiointoxication after balloon rupture and laboratory contamination in case of a spill. We hypothesized that the positron emitter (68)Ga, with a half-life of only 68 minutes, was well suited to overcome these safety obstacles while providing full therapeutic efficacy.

METHODS AND RESULTS

The feasibility, efficacy, and safety of (68)Ga liquid-filled balloon brachytherapy were investigated in the porcine coronary overstretch model. Four groups of 5 balloon-induced coronary lesions were irradiated with 8, 12, 16, and 24 Gy targeted to the adventitia. Ten unirradiated lesions served as controls. Segments treated with 16 or 24 Gy exhibited marked suppression of neointimal proliferation at 28-day follow-up, with quantitative parameters of intraluminal proliferation reduced to <20%. This beneficial effect was not compromised by untoward edge effects. Uninjured but irradiated vessels did not show histological signs of radiation damage. The (68)Ga whole-body dose due to balloon rupture was estimated to be 5 rem/50 mCi treatment activity and compared favorably with that of (188)Re (78 rem/50 mCi).

CONCLUSIONS

(68)Ga positron radiation suppresses neointimal proliferation at doses of 16 and 24 Gy. This biological efficacy, coupled with the attractive safety profile, suggests the selection of (68)Ga as an attractive isotope for liquid-filled balloon brachytherapy.

Primary genitourinary melanoma

OBJECTIVES

To describe the presentation, management, and clinical outcome of patients with genitourinary melanoma.

METHODS

We identified 14 patients with genitourinary melanoma treated at Memorial Sloan-Kettering Cancer Center, New York and Tripler Army Medical Center, Honolulu, Hawaii. The presentation, surgical treatment, disease progression, and outcome of these patients were reviewed. Survival was analyzed, using the Kaplan-Meier product limit method.

RESULTS

The presentation and management of patients with genitourinary melanoma were varied. Overall, the prognosis was poor, with a median survival of 43 months, and only 3 patients were alive, without disease, at last follow-up. Our findings confirm a poor prognosis in patients with this rare disease.

CONCLUSIONS

Genitourinary melanoma is a rare form of the disease with an unfavorable clinical outcome. Less than one third of patients survive long term, although patients with scrotal melanomas may have a better prognosis.

Beneficial influence of recombinant human erythropoietin therapy on the rate of progression of chronic renal failure in predialysis patients

BACKGROUND

Partial correction of anaemia with recombinant human erythropoietin (rHuEpo) has been shown to markedly improve the general condition and quality of life of predialysis patients, but the effects of rHuEpo therapy on blood pressure and the rate of progression of chronic renal failure (CRF) are still disputed. In particular, no study evaluated the time duration until the start of maintenance dialysis in treated patients, compared to untreated predialysis patients.

METHODS

We retrospectively evaluated the rate of decline of creatinine clearance (Delta Ccr) and the duration of the predialysis period in 20 patients with advanced CRF treated with rHuEpo (Epo+ group), and in 43 patients with a similar degree of CRF but with less marked, asymptomatic anaemia, not requiring rHuEpo therapy (Epo- group). All patients were submitted to identical clinical and laboratory surveillance. All received similar oral supplementation with B(6), B(9), and B(12) vitamins and oral iron supplementation. Maintenance dose of subcutaneous epoetin was 54.3+/-16.5 U/kg/week (median dose 3300 U/week).

RESULTS

Initial and final haemoglobin (Hb) levels were 8.8+/-0.7 and 11.3+/-0.9 g/dl in the Epo+ group, vs 10.9+/-1.2 and 9.5+/-0.9 g/dl in the Epo- group. In the Epo+ group, Delta Ccr declined from 0.36+/-0.16 during the preceding 24 months to 0.26+/-0.15 ml/min/ 1.73 m(2)/month after the start of rHuEpo therapy (P<0.05). No significant variation was observed in the Epo- group. Time duration until the start of dialysis was 16.2+/-11.9 in the Epo+ group, compared to 10.6+/-6.1 months in the Epo- group (P<0.01). Slowing of progression was observed in 10 Epo+ patients, whereas no significant variation in Delta Ccr occurred in the other 10. There was no difference in previous Delta Ccr rate, nor in Hb or blood pressure levels while on rHuEpo therapy between the two subgroups.

CONCLUSIONS

Our study affords conclusive evidence that rHuEpo therapy did not result in accelerated progression of CRF in any treated predialysis patients, nor deleterious increase in blood pressure, but instead resulted in significant slowing of progression and substantial retardation of maintenance dialysis. Such encouraging results remain to be validated in a large prospective, randomized study.

Individual cholesterol variation in response to a margarine- or butter-based diet: A study in families

CONTEXT

The effectiveness of dietary modification in reducing low-density lipoprotein cholesterol (LDL-C) levels can be reliably predicted for populations, but not for individuals.

OBJECTIVE

To determine whether individual variation in cholesterol response to dietary modification is a familial trait.

DESIGN

Two-period, outpatient crossover trial conducted from September 1997 to September 1999.

SETTING AND PARTICIPANTS

Fifty-six families from the Dallas-Ft Worth, Tex, area with 2 biological parents and at least 2 children aged 5 years or older volunteered; 46 families (n = 92 adults and n = 134 children) completed the study.

INTERVENTION

All families followed two 5-week dietary regimens that included individualized daily dietary prescriptions and emphasized a low-saturated fat diet supplemented with specially manufactured baked goods and spreadable fat. One regimen used butter only and the other used margarine only.

MAIN OUTCOME MEASURE

Mean LDL-C levels during the last 2 weeks of each dietary period.

RESULTS

Margarine intake compared with butter intake lowered LDL-C levels 11% in adults (95% confidence interval [CI], 13% to 9%) and 9% in children (95% CI, 12% to 6%) (P<.001 for both adults and children). The distribution of individual responses were peaked around the mean response. For adults and children together, family membership accounted for 19% of variability in response (P =.007). In children, family membership accounted for 40% of variability in response of percent change in LDL-C levels (P =.002). Body mass index and change in cholesterol ester (CE) 18:2/18:1 ratio accounted for 26% of variation, leaving 26% still attributable to family membership. In all participants, BMI predicted response-heavier individuals had higher LDL-C levels, less excursion in CE fatty acids, and less LDL-C response to dietary change.

CONCLUSIONS

Our results suggest that individual variation in response to a cholesterol-lowering diet is a familial trait. Body weight is an important modifiable factor that influences response. JAMA. 2000;284:2740-2747.

Ritonavir increases the level of active ADD-1/SREBP-1 protein during adipogenesis

OBJECTIVE

A novel lipodystrophy syndrome characterized by truncal adiposity, peripheral fat atrophy, type 2 diabetes mellitus, and dyslipidemia occurs in HIV-infected individuals, and may be aggravated by HIV-1 protease inhibitors. The increase in truncal fat could be due to enhanced preadipocyte differentiation. Using the 3T3-L1 preadipocyte model, we reported that ritonavir enhances adipocyte differentiation in culture. The goal of this study was to characterize the molecular mechanism of ritonavir on preadipocyte differentiation.

DESIGNS AND METHODS

Time course studies of 3T3-L1 preadipocytes placed in standard differentiation medium (insulin, dexamethasone, and isobutylmethylxanthine) were performed. Glycerol phosphate dehydrogenase (GPDH) was assayed enzymatically, and triacylglycerol (TG) mass was quantified. The adipogenic transcription factors adipocyte determination and differentiation-dependent factor 1 (ADD-1)/sterol regulatory element binding protein 1 (SREBP-1), CCAAT/enhancer-binding protein-alpha (CEBPalpha), and peroxisome proliferator activated receptor-gamma (PPARgamma), were measured by Western analysis.

RESULTS

Ritonavir (10 microg/ml) enhanced 3T3-L1 preadipocyte differentiation (30% increase in TG mass; 50% increase in GPDH activity), and transiently raised levels of the 68 kDa active mature form of ADD-1/SREBP-1 during adipogenesis by threefold, compared with standard differentiation. In contrast, ritonavir attenuated the differentiation-induced increase in CEBPalpha and PPARgamma.

CONCLUSIONS

Our data suggest that ritonavir enhances 3T3-L1 adipogenesis by increasing the level of active mature ADD-1/SREBP-1. This effect may be due to reduced proteolysis of ADD-1/SREBP-1, as ritonavir inhibits an N-acetyl-leucyl-leucyl-norleucinal (ALLN)-sensitive proteosomal degradation pathway in lymphocytes, and ALLN itself inhibits the breakdown of mature ADD-1/SREBP-1. As mature ADD-1/SREBP-1 regulates several lipogenic enzymes, higher levels may explain the effect of ritonavir on TG accumulation and GPDH activity. Studying ADD-1/SREBP-1 may lead to better understanding and prevention of the lipodystrophy syndrome.

Good visual function in posterior microphthalmos

Posterior microphthalmos is a rare condition in which the anterior segment is normal in size and configuration, but the posterior segment is reduced in size; this results in axial hyperopia and retinal folding. Patients have decreased vision that is caused by posterior segment abnormalities, high refractive error, and amblyopia. We present a case of posterior microphthalmos in which retinal function was relatively intact and visual loss was believed to be primarily caused by refractive error and amblyopia. After treatment, the child's visual acuity and school performance improved. This case emphasizes the need for careful examination, refraction, and follow-up for these children because their visual potential may be reasonably good.

Promoting cancer prevention activities among Vietnamese physicians in California

BACKGROUND

To promote prevention and early detection of cancer, the authors conducted a three-year intervention targeting Vietnamese physicians in solo practice in California.

METHODS

Twenty subjects who had received their medical training in Vietnam were recruited into a randomized controlled trial. The intervention included computerized or manual cancer screening reminders, continuing medical education seminars, Vietnamese-language health education materials, newsletters, and oncology data-query programs. Evaluation included chart audits for eight targeted activities pre- and post-intervention.

RESULTS

Before the intervention, annual physician performance rates were low for all eight activities: routine checkups (65.6%), Pap testing (13.8%), pelvic examinations (19.8%), clinical breast examinations (13.3%), mammography (6.4%), hepatitis B serologies (21.9%), hepatitis B immunizations (12.8%), and smoking cessation counseling (1.6%). After the intervention, performance rates increased significantly for smoking cessation counseling (p = 0.02), Pap testing (p = 0.004), and pelvic examinations (p = 0.01).

CONCLUSIONS

The results demonstrate the efficacy of an intervention targeting Vietnamese primary care physicians in promoting smoking cessation counseling, Pap testing, and pelvic examinations, but not other cancer prevention activities.

Sustained reduction of hyperhomocysteinaemia with folic acid supplementation in predialysis patients

BACKGROUND

Moderate hyperhomocysteinaemia, as occurs in chronic renal failure patients, is an established independent risk factor for atherosclerotic arterial occlusive accidents, the incidence of which is abnormally high in such patients. Folic acid supplementation has been shown to reduce plasma homocysteine level in end-stage renal disease patients treated with haemodialysis or peritoneal dialysis, but its long-term effects in predialysis patients had not been assessed.

METHODS

We prospectively treated a total of 78 predialysis patients with folic acid for at least 1 year (range 12-74 months) together with oral pyridoxine and vitamin B12 supplements. Of the patients, 67 received 5 mg folic acid three times per week, whereas the other 11 patients who were treated with recombinant erythropoietin received 5 mg/day. Plasma fasting total homocysteine concentration was determined at baseline, after 3 months and at the end of follow-up.

RESULTS

Mean (+/-SD) plasma total homocysteine level decreased from 21.2+/-6.4 micromol/l at baseline to 14.2+/-4.6 at 3 months and remained at 12.8+/-3.7 micromol/l at the end of follow-up (average duration 2.8 years), whereas plasma creatinine rose from 268+/-129 to 399+/-234 micromol/l. Mean plasma folate concentration rose from 19+/-12 to 47+/-13 nmol/l and mean plasma vitamin B12 rose from 237+/-119 to 347+/-191 pmol/l from baseline to end of follow-up.

CONCLUSIONS

Moderate folic acid supplementation (2.15 mg/day) allows a substantial (40% as a mean) and sustained (up to 6 years) reduction of plasma total homocysteine level in predialysis uraemic patients without any detectable side effect. Folic acid supplementation may thus contribute to lower the risk of accelerated atherosclerosis in such patients.

Human alpha1,3/4-fucosyltransferases. III. A Lys/Arg residue located within the alpha1,3-FucT motif is required for activity but not substrate binding

Amino acid sequence alignment of human alpha1, 3/4-fucosyltransferases (FucTs) demonstrates that three highly conserved Lys residues are present in the catalytic domain of FucTs III, IV, V, and VI. Two of these sites are conserved in FucT VII, with the third located within the alpha1,3-FucT motif as a conservative change to Arg at position 223. Site-directed mutagenesis experiments were conducted to change Lys255 of FucT V (equivalent to Arg223 of FucT VII) to either Arg255 or Ala255. Enzyme assays demonstrate that the FucT V K255R mutant has a 34-fold lower specific activity than native FucT V and that the K255A mutant is inactive. Site-directed mutagenesis of FucT VII was also conducted to change Arg223 to Lys223 for analysis of the effect on enzyme kinetic parameters. No differences in acceptor specificities or Km values for either substrate were observed between native FucT VII and the R223K mutant; however, the purified R223K mutant enzyme had a 2-fold increased specific activity compared with purified native FucT VII. No change in GDP-fucose-protectable pyridoxal-P/NaBH4 inactivation was observed for native or mutant FucT V or VII, further supporting the absence of involvement of this residue in sugar nucleotide binding. The results indicate that a basic residue in this position is required for enzyme activity, with a Lys residue providing higher intrinsic activity. The lack of influence of this site on substrate binding parameters and its location within the alpha1,3-FucT motif suggest that at least some of the residues within this motif are involved in catalysis rather than substrate binding.

Human alpha1,3/4-fucosyltransferases. I. Identification of amino acids involved in acceptor substrate binding by site-directed mutagenesis

In a previous study (Xu, Z., Vo, L., and Macher, B. A. (1996) J. Biol. Chem. 271, 8818-8823), a domain swapping approach demonstrated that a region of amino acids found in human alpha1, 3/4-fucosyltransferase III (FucT III) conferred a significant increase in alpha1,4-FucT acceptor substrate specificity into alpha1, 3-fucosyltransferase V (FucT V), which, under the same assay conditions, has extremely low alpha1,4-FucT acceptor substrate specificity. In the current study, site-directed mutagenesis was utilized to identify which of the eight amino acids, associated with alpha1,4-FucT acceptor substrate specificity, is/are responsible for conferring this new property. The results demonstrate that increased alpha1,4-FucT activity with both disaccharide and glycolipid acceptors can be conferred on FucT V by modifying as few as two (Asn86 to His and Thr87 to Ile) of the eight amino acids originally swapped from FucT III into the FucT V sequence. Neither single amino acid mutant had increased alpha1,4-FucT activity relative to that of FucT V. Kinetic analyses of FucT V mutants demonstrated a reduced Km for Galbeta1,3GlcNAc (type 1) acceptor substrates compared with native FucT V. However, this was about 20-fold higher than that found for native FucT III, suggesting that other amino acids in FucT III must contribute to its overall binding site for type 1 substrates. These results demonstrate that amino acid residues near the amino terminus of the catalytic domain of FucT III contribute to its acceptor substrate specificity.

Advanced oxidation protein products as novel mediators of inflammation and monocyte activation in chronic renal failure

We previously demonstrated the presence of advanced oxidation protein products (AOPP), a novel marker of oxidative stress in the plasma of uremic patients receiving maintenance dialysis. The present study in a cohort of 162 uremic patients showed that plasma concentrations of AOPP increased with progression of chronic renal failure and were closely related to advanced glycation end products (AGE)-pentosidine (r = 0.52, p < 0.001), taken as a marker of AGE. In vivo, the relevance of AOPP and AGE-pentosidine in monocyte-mediated inflammatory syndrome associated with uremia was evidenced by close correlations between AOPP or AGE-pentosidine and monocyte activation markers, including neopterin, IL-1R antagonist, TNF-alpha, and TNF soluble receptors (TNF-sR55 and TNF-sR75). To determine the mechanisms by which AOPP and AGE could be directly involved in monocyte activation, AOPP-human serum albumin (HSA) and AGE-HSA were produced in vitro by treating HSA with oxidants or glucose, respectively. Spectroscopic analysis confirmed that AOPP-HSA contains carbonyls and dityrosine. Both AOPP-HSA and AGE-HSA, but not purified dityrosine, were capable of triggering the oxidative burst of human monocytes in cultures. The AOPP-HSA-induced respiratory burst was dependent on the chlorinated nature of the oxidant and on the molar ratio HSA/HOCI. Collectively, these data first demonstrate that AOPP act as a mediator of oxidative stress and monocyte respiratory burst, which points to monocytes as both target and actor in the immune dysregulation associated with chronic uremia.

Renal Na+, K+-ATPase in SHR: studies of activity and gene expression

The mechanism by which increased dietary intake of calcium reduces blood pressure in the spontaneously hypertensive rat is unknown. The present studies were designed to determine if there were alterations in the activity of the major membrane ion translocating pump, sodium, potassium-ATPase (NKA), in the kidneys of hypertensive rats and whether increased dietary calcium intake affected the activity of this enzyme. Fifteen-week old SHR's were found to have lower total ATPase activity in microsomal preparations from the kidney than age matched Wistar-Kyoto animals. Both the ouabain-sensitive component (NKA) and the ouabain-insensitive component were lower in SHR. Increasing dietary calcium intake from 1% to 3% elevated both components of the ATPase activity in SHR, but was without effect in WKY. Measurement of membrane phospholipid composition suggested that altered phospholipid composition did not account for the reduced ATPase activity observed, but indicated a reduced density of ATPase in SHR. A technique has been devised for qualitative and quantitative analysis of Na, K-ATPase alpha isoforms using RT-PCR. This technique reveals that the alpha 1 isoform is the sole catalytic isoform present in the nephron. Accurate and precise quantification of the amount of gene expression in individual nephron segments is reported and will be applied to determine whether dietary calcium influences blood pressure by a mechanism which alters nephron NKA gene expression.

[Benefits of early nephrological management of chronic renal failure]

OBJECTIVES

We evaluated whether early nephrological referral of patients with chronic renal failure (CRF) resulted in improved condition of patients at initiation of maintenance dialysis and in better outcome on dialysis.

PATIENTS AND METHODS

We prospectively recorded clinical status, laboratory parameters, length of hospital stay and outcome of 900 CRF patients who started maintenance dialysis at Necker hospital between January 1989 and December 1996. We compared patients who benefited regular nephrological follow-up, and patients who were referred in emergency conditions at the ultimate stage of CRF.

RESULTS

Among the 900 patients, 731 (81.2%) had regular nephrological follow-up, including 632 (70.2%, group IA) with optimal preparation to dialysis and 99 (11%, group IB) whose clinical course was complicated due to heavy comorbidity, whereas 169 (18.8%, group II) had no previous nephrological management. Over the 8-year observation period, the proportion of the latter group did not decrease. Late referred patients had higher blood pressure level, more frequent fluid overload, higher serum levels of urea, creatinine, uric acid and phosphate, and lower levels of bicarbonate, calcium, albumin and creatinine clearance that did well-prepared patients. Mean (+/- SD) hospital stay was 29.7 +/- 15.8 days in the former compared to only 4.8 +/- 3.3 days (p < 0.001) in the latter. Early deaths within 3 months of dialysis initiation were more frequent (7.1 vs 1.6% p < 0.05) and less patients subsequently were able to be treated out-center (20.1 vs 40.7%, p < 0.05) in group II than in group IA. The overcost induced by late referral may be estimated at 0.25 million French francs per patient.

CONCLUSION

An unjustified late nephrological referral of CRF patients still is observed in nearly 20% of cases. Such late referral is detrimental to both patients in terms of altered quality of life and long hospital stay, and to the collectivity due to heavy overcost. Closer cooperation between family physicians and nephrologists is needed to provide optimal management and allow timely preparation to maintenance dialysis of CRF patients.

[Benefits of early nephrological management in chronic renal failure]

OBJECTIVES

We evaluated whether early nephrological referral of patients with chronic renal failure (CRF) resulted in improved condition of patients at initiation of maintenance dialysis and in better outcome on dialysis.

PATIENTS AND METHODS

We prospectively recorded clinical status, laboratory parameters, length of hospital stay and outcome of 900 CRF patients who started maintenance dialysis at Necker hospital between January 1989 and December 1996. We compared patients who benefited regular nephrological follow-up, and patients who were referred in emergency conditions at the ultimate stage of CRF.

RESULTS

Among the 900 patients, 731 (81.2%) had regular nephrological follow-up, including 632 (70.2%, group IA) with optimal preparation to dialysis and 99 (11%, group IB) whose clinical course was complicated due to heavy comorbidity, whereas 169 (18.8%, group II) had no previous nephrological management. Over the 8-year observation period, the proportion of the latter group did not decrease. Late referred patients had higher blood pressure level, more frequent fluid overload, higher serum levels of urea, creatinine, uric acid and phosphate, and lower levels of bicarbonate, calcium, albumin and creatinine clearance that did well-prepared patients. Mean (+/- SD) hospital stay was 29.7 +/- 15.8 days in the former compared to only 4.8 +/- 3.3 days (p < 0.001) in the latter. Early deaths within 3 months of dialysis initiation were more frequent (7.1 vs 1.6%, p < 0.05) and less patients subsequently were able to be treated out-center (20.1 vs 40.7%, p < 0.05) in group II than in group IA. The overcost induced by late referral may be estimated at 0.25 million French francs per patient.

CONCLUSION

An unjustified late nephrological referral of CRF patients still is observed in nearly 20% of cases. Such late referral is detrimental to both patients in terms of altered quality of life and long hospital stay, and to the collectivity due to heavy overcost. Closer cooperation between family physicians and nephrologists is needed to provide optimal management and allow timely preparation to maintenance dialysis of CRF patients.

Severe pulmonary hypertension in liver transplant candidates

Advanced liver disease with portal hypertension may be associated with pulmonary hypertension. A review of 1,205 consecutive liver transplant patients was made to assess the incidence and severity of pulmonary hypertension in patients with end-stage liver disease. Postoperative data were reviewed to determine if outcome was influenced and, in patients with severe pulmonary hypertension, whether pulmonary hypertension was reversed after transplantation. The hemodynamic data of 5 patients who were found to have severe pulmonary hypertension before transplantation and did not receive transplants were also reviewed. The incidence of pulmonary hypertension in the patients who received transplants was 8.5% (n = 102; mean pulmonary artery pressure, > 25 mmHg). The incidence of mild pulmonary hypertension was 6.72% (n = 81; systolic pulmonary artery pressure, 30 to 44 mmHg); that of moderate pulmonary hypertension was 1.16% (n = 14; systolic pulmonary artery pressure, 45 to 59 mmHg); and that of severe pulmonary hypertension was 0.58% (n = 7; systolic pulmonary artery pressure, > 60 mmHg). Mild and moderate pulmonary hypertension did not influence the outcome of the procedure. Severe pulmonary hypertension was associated with mortality rates of 42% at 9 months posttransplantation and 71% at 36 months posttransplantation. Only 2 of 7 patients with severe pulmonary hypertension have survived liver transplantation with a good quality of life. The remaining 5 patients continued to deteriorate with progressive right heart failure with no evidence of amelioration of the pulmonary hypertension. This experience supports the view that in most patients who have severe pulmonary hypertension associated with advanced liver disease, it is caused by fixed pathological changes in the pulmonary vasculature, is not reversible with liver transplantation, and is associated with a very high perioperative mortality rate.

Continuous small-dose tranexamic acid reduces fibrinolysis but not transfusion requirements during orthotopic liver transplantation

Tranexamic acid (TA) is a synthetic drug that inhibits fibrinolysis. It has been administered to decrease the use of blood products during cardiac surgery and orthotopic liver transplantation when infused in larger doses. A small-dose infusion of aprotinin causes a reduction in fibrinolysis and blood product requirement during orthotopic liver transplantation without apparent risk of intravascular thrombosis. This prospective study was designed to investigate whether a small-dose infusion of TA would be equally effective in reducing fibrinolysis and blood product transfusions during orthotopic liver transplantation. A double-blind, controlled study was undertaken to compare the efficacy of a small-dose TA infusion with that of a placebo. Thirty-two consecutive patients were randomized either to the TA group (n = 16), which received an intravenous infusion of 2 mg x kg(-1) x h(-1), or to the control group (n = 16), which received an identical volume of normal saline. Coagulation values were measured, a field rating was made by the surgeon, and a thromboelastogram was produced at four predetermined intervals throughout the case-before TA infusion was started, after portal vein ligation, 10 min after reperfusion, and at the end of surgery. Intraoperative transfusion requirements were recorded during the procedure and for the first 24 h postoperatively. A record was kept of any intraoperative epsilon-aminocaproic acid administered for uncontrolled fibrinolysis. The thromboelastogram clot lysis index was significant for lysis in the control group during both the anhepatic and the neohepatic phases (P < 0.01 and P < 0.05, respectively) when compared with the TA group. Fibrin degradation products were significantly increased (>20 microg/mL) in the control group at reperfusion (P < 0.03) and at the end of surgery (P < 0.01). D-dimers were also significantly increased (>1 mg/L) in the control group at the end of surgery (P < 0.04). Nine of the 16 control patients versus 3 of the 16 TA patients required epsilon-aminocaproic acid rescue for fibrinolysis. There were no other significant differences between groups. Transfusion requirements during surgery and for the first 24 h postoperatively did not differ significantly between the two groups. We conclude that the use of small-dose TA reduces fibrinolysis but not transfusion requirements during orthotopic liver transplantation.

Duration of rocuronium-induced neuromuscular block during liver transplantation: a predictor of primary allograft function

The prolongation of vecuronium-induced neuromuscular block has been reported as a predictor of hepatic allograft dysfunction. This study investigates the duration of action of rocuronium, which also relies on hepatic clearance, to examine whether it also is prolonged with allograft dysfunction. Fifty-seven patients undergoing orthotopic liver transplant were given rocuronium (0.6 mg/kg) prior to allograft placement and the recovery of contraction of the orbicularis oculi muscle to a 2-Hz train-of-four stimulus was recorded. Fifteen minutes after reperfusion of the allograft, rocuronium (0.6 mg/kg) was administered and the time to recovery of muscle contraction to a train-of-four stimulus (train-of-four time) was again recorded. The patients were divided into two groups according to posttransplant liver function. Group I consisted of 50 patients with immediate normal liver function. Group II contained 7 patients with primary dysfunctional livers. Primary dysfunction was determined by peak serum aspartate aminotransferase and alanine aminotransferase levels > 2000 U/L, and prothrombin time > 16 s. The train-of-four time in Group II was prolonged compared with Group I (P < 0.05). Immediate graft function testing using the recovery time from rocuronium of > 150 min has a positive predictive value of 100% and a negative predictive value of 96%. The sensitivity and specificity is 71% and 100%, respectively. Receiver operating characteristic analysis supports this conclusion.

Nitric oxide does not reverse pulmonary hypertension associated with end-stage liver disease: a preliminary report

Pulmonary hypertension is a well known, though uncommon complication of end-stage liver disease (ESLD). Patients with severe pulmonary hypertension and ESLD undergoing orthotopic liver transplantation (OLT) may develop right ventricular failure and death. This study investigates the reversibility of pulmonary hypertension by the inhalation of nitric oxide in patients under evaluation for OLT. Ten patients with ESLD who were discovered to have moderate to severe pulmonary hypertension were administered nitric oxide via face mask in concentrations ranging from 0 to 80 ppm. Inhaled nitric oxide is a potent pulmonary vasodilator without apparent systemic effects. Nitric oxide had no demonstrable effect on mean pulmonary artery pressure (PAP) (37 vs. 37 mm Hg), transpulmonary gradient (TPG) (26 vs. 26 mm Hg), or pulmonary vascular resistance (PVR) (295 vs. 288 dynes x sec x cm (-5)). Two patients were discovered to have an elevated pulmonary artery occlusion pressure (PAOP) on baseline readings. The cause of pulmonary hypertension in these two patients was secondary to volume overload as a result of hepato-renal syndrome rather than primary pulmonary arteriolar pathology and was responsive to diuresis or dialysis but not to nitric oxide therapy. In conclusion nitric oxide does not reverse pulmonary hypertension associated with ESLD.

Disturbed myeloperoxidase-dependent activity of neutrophils in cystic fibrosis homozygotes and heterozygotes, and its correction by amiloride

The present study addresses the question of a possible linkage between the cystic fibrosis (CF) genetic autosomal recessive disorder and disturbance in neutrophil function. Neutrophil-dominated chronic airway inflammation is present at an early age in children with CF, even in the absence of detectable infection. As evidenced by extracellular superoxide anion release (measured by lucigenin luminescence) or intracellular hydrogen peroxide production (measured by 2',7'-dichlorofluorescein (DCF) fluorescence), no significant difference in the nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase activity of isolated neutrophils was observed in noninfected CF children (homozygotes), their mothers or fathers (CF heterozygotes), and controls. In contrast, both myeloperoxidase (MPO)-dependent oxygenation activity (measured by luminol luminescence) and chloramine release were increased significantly in both CF homozygotes and heterozygotes as compared with controls. In the presence of either amiloride (a sodium channel inhibitor and sodium/proton antiport blocker) or EIPA (5-ethyl-N-isopropyl-amiloride, a specific inhibitor of the antiport), or choline buffer, intracellular MPO activity was decreased significantly in controls and in the CF homozygotes and heterozygotes, thus bringing intracellular MPO-dependent activity in CF subjects back to the level of controls. Extracellular release of MPO, measured by an ELISA to provide an activity-independent assessment of the enzyme, was increased only in CF homozygotes, and was decreased by amiloride and choline buffer, but not by EIPA. We conclude that a modification of intracellular pH and/or ionic concentrations may be related to the altered MPO enzymatic activity observed in CF neutrophils.

Disturbed myeloperoxidase-dependent activity of neutrophils in cystic fibrosis homozygotes and heterozygotes, and its correction by amiloride

The present study addresses the question of a possible linkage between the cystic fibrosis (CF) genetic autosomal recessive disorder and disturbance in neutrophil function. Neutrophil-dominated chronic airway inflammation is present at an early age in children with CF, even in the absence of detectable infection. As evidenced by extracellular superoxide anion release (measured by lucigenin luminescence) or intracellular hydrogen peroxide production (measured by 2',7'-dichlorofluorescein (DCF) fluorescence), no significant difference in the nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase activity of isolated neutrophils was observed in noninfected CF children (homozygotes), their mothers or fathers (CF heterozygotes), and controls. In contrast, both myeloperoxidase (MPO)-dependent oxygenation activity (measured by luminol luminescence) and chloramine release were increased significantly in both CF homozygotes and heterozygotes as compared with controls. In the presence of either amiloride (a sodium channel inhibitor and sodium/proton antiport blocker) or EIPA (5-ethyl-N-isopropyl-amiloride, a specific inhibitor of the antiport), or choline buffer, intracellular MPO activity was decreased significantly in controls and in the CF homozygotes and heterozygotes, thus bringing intracellular MPO-dependent activity in CF subjects back to the level of controls. Extracellular release of MPO, measured by an ELISA to provide an activity-independent assessment of the enzyme, was increased only in CF homozygotes, and was decreased by amiloride and choline buffer, but not by EIPA. We conclude that a modification of intracellular pH and/or ionic concentrations may be related to the altered MPO enzymatic activity observed in CF neutrophils.

Presumed ocular tuberculosis in an AIDS patient

BACKGROUND

Prior to the advent of anti-tuberculosis medications, ocular manifestations of tuberculosis, including choroidal tubercles, were common.

METHODS

A 46-year-old Hispanic male with a history of AIDS, tuberculosis and treated neurosyphilis presented for examination complaining of decreased vision in the left eye. Ophthalmoscopy revealed a large, elevated, juxtapapillary lesion consistent with a choroidal tubercle or an intraocular lymphoma.

RESULTS

During follow-up, the lesion responded well to systemic anti-tuberculosis therapy.

CONCLUSIONS

With the recent increase in incidence of tuberculosis in both th general population and AIDS patients, ocular manifestations of tuberculosis once thought to be rare may be increasing. Ocular tuberculosis should be considered in the differential diagnosis of patients presenting with intraocular masses, especially in individuals at high risk for exposure.