Sample average treatment effect on the treated (SATT) analysis using counterfactual explanation identifies BMT and SARS-CoV-2 vaccination as protective risk factors associated with COVID-19 severity and survival in patients with multiple myeloma

Patients with multiple myeloma (MM), an age-dependent neoplasm of antibody-producing plasma cells, have compromised immune systems and might be at increased risk for severe COVID-19 outcomes. This study characterizes risk factors associated with clinical indicators of COVID-19 severity and all-cause mortality in myeloma patients utilizing NCATS' National COVID Cohort Collaborative (N3C) database. The N3C consortium is a large, centralized data resource representing the largest multi-center cohort of COVID-19 cases and controls nationwide (>16 million total patients, and >6 million confirmed COVID-19+ cases to date). Our cohort included myeloma patients (both inpatients and outpatients) within the N3C consortium who have been diagnosed with COVID-19 based on positive PCR or antigen tests or ICD-10-CM diagnosis code. The outcomes of interest include all-cause mortality (including discharge to hospice) during the index encounter and clinical indicators of severity (i.e., hospitalization/emergency department/ED visit, use of mechanical ventilation, or extracorporeal membrane oxygenation (ECMO)). Finally, causal inference analysis was performed using the Coarsened Exact Matching (CEM) and Propensity Score Matching (PSM) methods. As of 05/16/2022, the N3C consortium included 1,061,748 cancer patients, out of which 26,064 were MM patients (8,588 were COVID-19 positive). The mean age at COVID-19 diagnosis was 65.89 years, 46.8% were females, and 20.2% were of black race. 4.47% of patients died within 30 days of COVID-19 hospitalization. Overall, the survival probability was 90.7% across the course of the study. Multivariate logistic regression analysis showed histories of pulmonary and renal disease, dexamethasone, proteasome inhibitor/PI, immunomodulatory/IMiD therapies, and severe Charlson Comorbidity Index/CCI were significantly associated with higher risks of severe COVID-19 outcomes. Protective associations were observed with blood-or-marrow transplant/BMT and COVID-19 vaccination. Further, multivariate Cox proportional hazard analysis showed that high and moderate CCI levels, International Staging System (ISS) moderate or severe stage, and PI therapy were associated with worse survival, while BMT and COVID-19 vaccination were associated with lower risk of death. Finally, matched sample average treatment effect on the treated (SATT) confirmed the causal effect of BMT and vaccination status as top protective factors associated with COVID-19 risk among US patients suffering from multiple myeloma. To the best of our knowledge, this is the largest nationwide study on myeloma patients with COVID-19.

Cancer-associated mesothelial cells are regulated by the anti-Müllerian hormone axis

Cancer-associated mesothelial cells (CAMCs) in the tumor microenvironment are thought to promote growth and immune evasion. We find that, in mouse and human ovarian tumors, cancer cells express anti-Müllerian hormone (AMH) while CAMCs express its receptor AMHR2, suggesting a paracrine axis. Factors secreted by cancer cells induce AMHR2 expression during their reprogramming into CAMCs in mouse and human in vitro models. Overexpression of AMHR2 in the Met5a mesothelial cell line is sufficient to induce expression of immunosuppressive cytokines and growth factors that stimulate ovarian cancer cell growth in an AMH-dependent way. Finally, syngeneic cancer cells implanted in transgenic mice with Amhr2-/- CAMCs grow significantly slower than in wild-type hosts. The cytokine profile of Amhr2-/- tumor-bearing mice is altered and their tumors express less immune checkpoint markers programmed-cell-death 1 (PD1) and cytotoxic T lymphocyte-associated protein 4 (CTLA4). Taken together, these data suggest that the AMH/AMHR2 axis plays a critical role in regulating the pro-tumoral function of CAMCs in ovarian cancer.

COVID-19 omicron variants demonstrated different virulence in infected patients with cancer: The real-world evidence from the National COVID Cohort Collaborative (N3C)

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Background: Comprehensive real-world evidence of the virulence of COVID-19 Omicron, Delta, and Alpha variants as well as the effectiveness of booster vaccinations in patients with cancer are lacking. We aimed to fill in these gaps for cancer patients and provide essential insights on the management of the fast-evolving pandemic by leveraging the nationally-representative electronic medical records from the National COVID Cohort Collaborative (N3C) registry. Methods: The virulence of COVID-19 variants was examined according to severe outcomes of infected patients with cancer, compared with non-cancer patients, using the N3C data between 12/01/2020 and 02/03/2022. Variants were inferred according to the time periods of variant dominance at > 95% accuracy. The Cox proportional hazards model was employed to evaluate the effects of COVID-19 variants, adjusting for age, gender, race/ethnicity, geographic regions, vaccination status, cancer types, smoking status, cancer treatments, and adjusted Charlson Comorbidity Index (CCI). Results: Our study cohort included 114,195 COVID-19 patients with cancer and 160,493 without cancer as control. Among them, 52,539 (21%) were infected by Omicron, 82,579 (33%) by Delta, and 115,200 (46%) by Alpha variants. Prior to the COVID-19 breakthrough infection, 7%, 22%, 3%, and 69% were vaccinated with 1 dose, 2 doses, a booster, or unvaccinated respectively. The proportions of hospitalization and death among patients with vs without cancer were 40% and 7% vs 18% and 0.4%, respectively. Characteristics of the cancer subcohort are summarized in the Table. Our analysis showed dramatically lower risks of severe outcomes for patients who were infected by Omicron (HR 0.42, 95%CI: 0.38 – 0.46) and slightly lower risks for Delta (HR 0.93, 95%CI: 0.89 – 0.98) compared with those infected by Alpha, after adjusting for other demographic clinical risk factors, and vaccination status. This trend remained similar in subgroups of patients with solid tumors, hematologic malignancies, or without cancer. Similar associations were observed when virulence was evaluated in association with mortality. The effectiveness of booster vaccinations varied across sub-cohorts stratified by variants and cancer types. Booster shots reduced the risk of severe outcomes for patients with solid tumors infected by Omicron variant or hematologic malignancies infected by Delta variants. Conclusions: Our work provides up-to-date and comprehensive real-world evidence of the virulence of COVID-19 variants in patients with cancer. Omicron variant showed significantly reduced virulence for different cancer types.[Table: see text]

Major risk factors associated with severe COVID-19 outcomes in patients with multiple myeloma: Report from the National COVID-19 Cohort Collaborative (N3C)

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Background: Patients with multiple myeloma (MM), an age-dependent neoplasm of antibody-producing plasma cells, have compromised immune systems due to multiple factors that may increase the risk of severe COVID-19. The NCATS’ National COVID Cohort Collaborative (N3C) is a centralized data resource representing the largest multi-center cohort of ̃12M COVID-19 cases and controls nationwide. In this study, we aim to analyze risk factors associated with COVID-19 severity and death in MM patients using the N3C database. Methods: Our cohort included MM patients within the N3C registry diagnosed with COVID-19 based on positive PCR or antigen tests or ICD-10–CM. The outcomes of interest include all-cause mortality (including discharge to hospice) during the index encounter, and clinical indicators of severity (hospitalization/ED visit, use of mechanical ventilation, or extracorporeal membrane oxygenation/ECMO). Results: As of 09/10/2021, the N3C registry included 690371 cancer patients, out of which 17791 were MM patients (4707 were COVID-19+). The mean age at diagnosis was 65.9yrs, 57.6% were >65yo, 46.4% were females, and 21.8% were Blacks. 25.6% had a Charlson Comorbidity Index (CCI) score of ≥2. 55.6% required an inpatient or ED visit, and 3.65% required invasive ventilation. 11.4% developed acute kidney injury during hospitalization. Multivariate logistic regression analysis showed histories of pulmonary disease (OR 2.2; 95%CI: 1.7-2.8), renal disease (OR 1.8; 95%CI: 1.4-2.4), and black race (p<0.001) were associated with higher risk of severity. Interestingly, smoking status was significantly associated with a lower risk of severity (OR 0.7; 95%CI: 0.5-0.9). Further, protective association was also observed between COVID-19 severity and blood or marrow transplant (BMT) (OR 0.52; 95%CI: 0.4-0.7), daratumumab therapy (OR 0.64; 95%CI: 0.42-0.99) and COVID-19 vaccination (OR 0.28; 95%CI: 0.18-0.44). IMiDs were associated increase in the risk of COVID-19 severity (OR 2.1; 95%CI: 1.6-2.7). 2.3% of N3C-myeloma COVID-19+ patients died within the first 10 days, while 4.95% died within 30 days of COVID-19 hospitalization. Overall, the survival probability was 90.5% across the course of the study. Multivariate cox proportional hazard model showed that CCI score ≥2 (HR 4.4; 95%CI: 2.2-8.8), hypertension (HR 1.6; 95%CI: 1.02-2.4), IMiD (HR 2.6; 95%CI: 1.8-3.8) and proteasome inhibitor (HR 1.6; 95%CI: 1.1-2.5) therapy were associated with worse survival. COVID-19 vaccination (HR 0.195; 95%CI: 0.09-0.45) and BMT (HR 0.65; 95%CI: 0.4-0.995) were associated with lower risk of death. Conclusions: We have identified previously unpublished potential risk factors for COVID-19 severity and death in MM as well as validated some published ones. To the best of our knowledge, this is the largest nationwide study on multiple myeloma patients with COVID-19.

Long COVID-19 in patients with cancer: Report from the National COVID Cohort Collaborative (N3C)

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Background: Post-acute sequelae of SARS-CoV-2 or long COVID, is characterized by persistence of symptoms and/or emergence of new symptoms post COVID-19 infection. As evidence accumulates and national initiatives arise to address this increasingly prevalent syndrome, characterization of specific patient groups is still lacking including patients with cancer. Using a nationally representative sample of over 4.3M COVID-19 patients from the National COVID Cohort Collaborative (N3C), we aim to describe characteristics of patients with cancer and long COVID. Methods: We employed two approaches to identify long COVID patients within N3C: i) patients presenting to a long COVID clinic at four N3C sites and ii) patients diagnosed using the recently introduced ICD-10 code: U09.9 Post COVID-19 condition, unspecified. We included patients with at least one positive COVID-19 diagnosis between 1/1/2020 and 2/3/2022. Patients had to survive at least 90 days from the date of their COVID-19 diagnosis. Analyses were performed in the N3C Data Enclave on the Palantir platform. Results: A total of 1700 adult patients with long COVID were identified from the N3C cohort; 634 (37.3%) were cancer patients and 1066 were non-cancer controls. The most common represented cancers were skin (21.9%), breast (17.7%), prostate (8.3%), lymphoma (8.0%) and leukemia (5.7%). Median age of long-COVID cancer patients was 64 years (Interquartile Range: 54-72), 48.6% were 65 years or older, 60.4% females, 76.8% non-Hispanic White, 12.3% were Black, and 3% Hispanic. A total of 41.1% were current or former smokers, 27.7% had an adjusted Charlson Comorbidity Index score of 0, 18.6% score of 1 and 11.2% score of 2. A total of 57.2% were hospitalized for their initial COVID-19 infection, the average length of stay in the hospital was 9.6 days (SD: 16.7 days), 9.1% required invasive ventilation, and 13% had acute kidney injury during hospitalization. The most common diagnosis among the non-cancer long COVID patients was asthma (26%), diabetes (17%), chronic kidney disease (12%), heart failure (9.4%), and chronic obstructive pulmonary disease (7.8%). Among long COVID patients, compared to non-cancer controls, cancer patients were more likely to be older (OR = 2.4, 95%CI: 1.1-5.4, p = 0.03), have comorbidities (OR = 4.3, 95%CI: 2.9-6.2, p < 0.0001), and to be hospitalized for COVID-19 (OR = 1.3, 95%CI: 1.0-1.7, p = 0.05), adjusting for sex, race/ethnicity, body mass index and smoking history. Conclusions: In a nationally representative sample of long COVID patients, there was a relative overrepresentation of patients with cancer. Compared to non-cancer controls, cancer patients were older, more likely to have more comorbidities and to be hospitalized for COVID-19 warranting further investigation to identify risk factors for long COVID in patients with cancer.

Single-Cell Proteomics and Tumor RNAseq Identify Novel Pathways Associated With Clofazimine Sensitivity in PI- and IMiD- Resistant Myeloma, and Putative Stem-Like Cells

Multiple myeloma (MM) is an incurable plasma cell malignancy with dose-limiting toxicities and inter-individual variation in response/resistance to the standard-of-care/primary drugs, proteasome inhibitors (PIs), and immunomodulatory derivatives (IMiDs). Although newer therapeutic options are potentially highly efficacious, their costs outweigh the effectiveness. Previously, we have established that clofazimine (CLF) activates peroxisome proliferator-activated receptor-γ, synergizes with primary therapies, and targets cancer stem-like cells (CSCs) in drug-resistant chronic myeloid leukemia (CML) patients. In this study, we used a panel of human myeloma cell lines as in vitro model systems representing drug-sensitive, innate/refractory, and clonally-derived acquired/relapsed PI- and cereblon (CRBN)-negative IMiD-resistant myeloma and bone marrow-derived CD138+ primary myeloma cells obtained from patients as ex vivo models to demonstrate that CLF shows significant cytotoxicity against drug-resistant myeloma as single-agent and in combination with PIs and IMiDs. Next, using genome-wide transcriptome analysis (RNA-sequencing), single-cell proteomics (CyTOF; Cytometry by time-of-flight), and ingenuity pathway analysis (IPA), we identified novel pathways associated with CLF efficacy, including induction of ER stress, autophagy, mitochondrial dysfunction, oxidative phosphorylation, enhancement of downstream cascade of p65-NFkB-IRF4-Myc downregulation, and ROS-dependent apoptotic cell death in myeloma. Further, we also showed that CLF is effective in killing rare refractory subclones like side populations that have been referred to as myeloma stem-like cells. Since CLF is an FDA-approved drug and also on WHO's list of safe and effective essential medicines, it has strong potential to be rapidly re-purposed as a safe and cost-effective anti-myeloma drug.

Risk and Outcome of Breakthrough COVID-19 Infections in Vaccinated Patients With Cancer: Real-World Evidence From the National COVID Cohort Collaborative

PURPOSE

To provide real-world evidence on risks and outcomes of breakthrough COVID-19 infections in vaccinated patients with cancer using the largest national cohort of COVID-19 cases and controls.

METHODS

We used the National COVID Cohort Collaborative (N3C) to identify breakthrough infections between December 1, 2020, and May 31, 2021. We included patients partially or fully vaccinated with mRNA COVID-19 vaccines with no prior SARS-CoV-2 infection record. Risks for breakthrough infection and severe outcomes were analyzed using logistic regression.

RESULTS

A total of 6,860 breakthrough cases were identified within the N3C-vaccinated population, among whom 1,460 (21.3%) were patients with cancer. Solid tumors and hematologic malignancies had significantly higher risks for breakthrough infection (odds ratios [ORs] = 1.12, 95% CI, 1.01 to 1.23 and 4.64, 95% CI, 3.98 to 5.38) and severe outcomes (ORs = 1.33, 95% CI, 1.09 to 1.62 and 1.45, 95% CI, 1.08 to 1.95) compared with noncancer patients, adjusting for age, sex, race/ethnicity, smoking status, vaccine type, and vaccination date. Compared with solid tumors, hematologic malignancies were at increased risk for breakthrough infections (adjusted OR ranged from 2.07 for lymphoma to 7.25 for lymphoid leukemia). Breakthrough risk was reduced after the second vaccine dose for all cancers (OR = 0.04; 95% CI, 0.04 to 0.05), and for Moderna's mRNA-1273 compared with Pfizer's BNT162b2 vaccine (OR = 0.66; 95% CI, 0.62 to 0.70), particularly in patients with multiple myeloma (OR = 0.35; 95% CI, 0.15 to 0.72). Medications with major immunosuppressive effects and bone marrow transplantation were strongly associated with breakthrough risk among the vaccinated population.

CONCLUSION

Real-world evidence shows that patients with cancer, especially hematologic malignancies, are at higher risk for developing breakthrough infections and severe outcomes. Patients with vaccination were at markedly decreased risk for breakthrough infections. Further work is needed to assess boosters and new SARS-CoV-2 variants.

Irg1/itaconate metabolic pathway is a crucial determinant of dendritic cells immune-priming function and contributes to resolute allergen-induced airway inflammation

Itaconate is produced from the mitochondrial TCA cycle enzyme aconitase decarboxylase (encoded by immune responsive gene1; Irg1) that exerts immunomodulatory function in myeloid cells. However, the role of the Irg1/itaconate pathway in dendritic cells (DC)-mediated airway inflammation and adaptive immunity to inhaled allergens, which are the primary antigen-presenting cells in allergic asthma, remains largely unknown. House dust mite (HDM)-challenged Irg1^-/- mice displayed increases in eosinophilic airway inflammation, mucous cell metaplasia, and Th2 cytokine production with a mechanism involving impaired mite antigen presentations by DC. Adoptive transfer of HDM-pulsed DC from Irg1-deficient mice into naïve WT mice induced a similar phenotype of elevated type 2 airway inflammation and allergic sensitization. Untargeted metabolite analysis of HDM-pulsed DC revealed itaconate as one of the most abundant polar metabolites that potentially suppress mitochondrial oxidative damage. Furthermore, the immunomodulatory effect of itaconate was translated in vivo, where intranasal administration of 4-octyl itaconate 4-OI following antigen priming attenuated the manifestations of HDM-induced airway disease and Th2 immune response. Taken together, these data demonstrated for the first time a direct regulatory role of the Irg1/itaconate pathway in DC for the development of type 2 airway inflammation and suggest a possible therapeutic target in modulating allergic asthma.

Short Palate, Lung, and Nasal Epithelial Clone1 (SPLUNC1) level determines steroid-resistant airway inflammation in aging

Asthma and its heterogeneity change with age. Increased airspace neutrophil numbers contribute to severe steroid-resistant asthma exacerbation in the elderly, which correlates with the changes seen in adults with asthma. However, whether that resembles the same disease mechanism and pathophysiology in aged and adults is poorly understood. Here, we sought to address the underlying molecular mechanism of steroid-resistant airway inflammation development and response to corticosteroid (Dex) therapy in aged mice. To study the changes in inflammatory mechanism, we used a clinically relevant treatment model of house-dust mite (HDM)-induced allergic asthma and investigated lung adaptive immune response in adult (20–22 wk old) and aged (80–82 wk old) mice. Our result indicates an age-dependent increase in airway hyperresponsiveness (AHR), mixed granulomatous airway inflammation comprising eosinophils and neutrophils, and Th1/Th17 immune response with progressive decrease in frequencies and numbers of HDM-bearing dendritic cells (DC) accumulation in the draining lymph node (DLn) of aged mice as compared with adult mice. RNA-Seq experiments of the aged lung revealed short palate, lung, and nasal epithelial clone 1 (SPLUNC1) as one of the steroid-responsive genes, which progressively declined with age and further by HDM-induced inflammation. Moreover, we found increased glycolytic reprogramming, maturation/activation of DCs, the proliferation of OT-II cells, and Th2 cytokine secretion with recombinant SPLUNC1 (rSPLUNC1) treatment. Our results indicate a novel immunomodulatory role of SPLUNC1 regulating metabolic adaptation/maturation of DC. An age-dependent decline in the SPLUNC1 level may be involved in developing steroid-resistant airway inflammation and asthma heterogeneity.

Target highlights in CASP13: Experimental target structures through the eyes of their authors

The functional and biological significance of selected CASP13 targets are described by the authors of the structures. The structural biologists discuss the most interesting structural features of the target proteins and assess whether these features were correctly reproduced in the predictions submitted to the CASP13 experiment.

Abstract LB-267: Transcriptomic and epigenomic analysis of metastatic castration-resistant prostate cancer and a pan-cancer analysis of its genetic signatures

Prostate cancer (PCa) is the 2nd leading cause of non-cutaneous cancer related deaths in the United States. The 5-year survival rate for local or regional disease is high. However, many patient’s disease will progress to the aggressive metastatic castration-resistant form of prostate cancer (mCRPC) - the estimated mortality rates of mCRPC is 19.5% for 2020 (www.cancer.org). Treatment with docetaxel or cabazitaxel alone or in combination with bevacizumab, thalidomide and prednisone increases survival rate slightly, but lead to drug resistance. The use of immunotherapy has further increased overall survival by 4-5 months. Therefore, a greater understanding of the underlying molecular mechanisms responsible for disease progression is needed.To understand and identify appropriate targets for therapy, we performed mRNA and miRNA expression studies and identified potential candidate cancer pathway genes and miRNA-mRNA pairs as biomarkers for aggressive Prostate cancer (mCRPC). Gene expression signatures were identified using differential expression (DE) analysis softwares. Spearman’s rank-based correlation and TargetScan were used to assess the association between mRNA and miRNA expression. We identified disparate mRNA and miRNA expression signatures for aggressive vs non-aggressive prostate cancers. The gene signatures were validated using the human prostate cancer patient cohort from The Cancer Genome Atlas (TCGA) database. The top ten genes that were significantly (p&lt;0.0001) associated with patient survival in PCa patients, stratified by Gleason scores, were PLAU, TGFB1, SERPINE1, MET, TIPM1, ITGA3, SERPINB5, PLAUR, CDKN1A and IGF1. Ingenuity Pathway Analysis (IPA) identified the activation of angiogenesis pathway as key factor for cancer aggressiveness. Epigenetic analysis showed distinct alterations in aggressive vs non-aggressive PCa. We also identified miRNA-mRNA pairs (including PLAU- mir181) which may influence differential gene expression in advanced-stage cancers. Furthermore, we performed a pan-cancer analysis of these top PCa survival-associated genes in other solid tumor types using patient expression profiles from the TCGA database. Our results identified significant (p&lt;0.05) associations of the expression of the following genes with cancer survival: PLAU (testicular, skin, lung, pancreatic and brain); TGBF1 (bladder, cervical and testicular); SERPINE1 (bladder and cervical); TIPM1 (bladder); ITGA3 (endometrial and cervical); SERPINB5 (endometrial); PLAUR (cervical); CDKN1A (bladder); and IGF1 (ovarian). In conclusion, we used genomic, transcriptomic and epigenomic approaches to identify and validate genetic signatures that may be used to further understand the molecular basis of aggressive cancers (specifically mCRPC) and develop personalized treatments with the goal of improving overall survival.

Citation Format: Taraswi Mitra Ghosh, Amit Kumar Mitra, Joshua Davis, Brian Cummings, Clayton Yates, Robert Arnold. Transcriptomic and epigenomic analysis of metastatic castration-resistant prostate cancer and a pan-cancer analysis of its genetic signatures [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-267.

Abstract LB-266: A novel computational combination-therapy prediction algorithm (secDrug) identifies the Nampt inhibitor FK866 reverses PI-resistant multiple myeloma

Drug resistance is a major cause of concern in cancer chemotherapy that not only reduces efficacy but also causes toxicity through overdosing. For example, Ixazomib, an oral proteasome inhibitor, has proven to remarkably improve myeloma patient outcomes but is associated with dose limiting toxicities and drug resistance. Therefore, new combination treatment regimens are urgently needed for the treatment of cancers, including multiple myeloma, which can lower the required dose of standard-of-care drug without compromising on treatment efficacy. We will present an optimization-regularization based computational prediction method called secDrug that uses large-scale pharmacogenomics databases to identify novel secondary drug combinations to reverse drug resistance. In this study, we applied secDrug to Ixazomib-resistant cell lines (&gt;100) in the Genomics of Drug Sensitivity in Cancer (GDSC) database and predicted that the following FDA-approved drug classes can be best combined with Ixazomib to overcome resistance in MM: nicotinamide phospho ribosyl transferase or Nampt inhibitor (FK866), HDAC inhibitors (Panobinostat, SAHA), neddylation inhibitor (MLN4924), Raf inhibitor (PLX-4720) and HSP90 inhibitor (17-AAG). Our results corroborate with earlier studies that have indicated these drugs could potentially be used in MM, alone or in combination. To validate our prediction results, we treated our panel of &gt;50 human multiple myeloma cell lines (Ix-sensitive and Ix-resistant HMCLs) with the top predicted drug combination - FK866 + Ixazomib. The results, based on combination index theorem, show that this combination works highly synergistically where the IC50 of ixazomib in MM cells was significantly reduced in presence of FK866. Similar results were obtained for the other top predicted combination regimens. Our findings provide a strong case for using secDrug for predicting secondary drugs in cancers resistant to the standard-of-care therapy. Furthermore, this provides additional evidence in support of combining FK866 with ixazomib to enhance sensitivity or overcome resistance to ixazomib and thereby improve patient outcome. Our future aim is to investigate the mechanism behind the synergism between proteasome inhibitors and the top drugs identified by our algorithm as candidates for secondary combination therapies using next-gen transcriptomics and single-cell approaches.

Citation Format: Harish Kumar, Ujjal Kumar Mukherjee, Sayak Chakravarti, Li Chen, Brian Van ness, Amit Kumar Mitra. A novel computational combination-therapy prediction algorithm (secDrug) identifies the Nampt inhibitor FK866 reverses PI-resistant multiple myeloma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-266.

Molecular signatures of multiple myeloma progression through single cell RNA-Seq

We used single cell RNA-Seq to examine molecular heterogeneity in multiple myeloma (MM) in 597 CD138 positive cells from bone marrow aspirates of 15 patients at different stages of disease progression. 790 genes were selected by coefficient of variation (CV) method and organized cells into four groups (L1–L4) using unsupervised clustering. Plasma cells from each patient clustered into at least two groups based on gene expression signature. The L1 group contained cells from all MGUS patients having the lowest expression of genes involved in the oxidative phosphorylation, Myc targets, and mTORC1 signaling pathways (p < 1.2 × 10⁻¹⁴). In contrast, the expression level of these pathway genes increased progressively and were the highest in L4 group containing only cells from MM patients with t(4;14) translocations. A 44 genes signature of consistently overexpressed genes among the four groups was associated with poorer overall survival in MM patients (APEX trial, p < 0.0001; HR, 1.83; 95% CI, 1.33–2.52), particularly those treated with bortezomib (p < 0.0001; HR, 2.00; 95% CI, 1.39–2.89). Our study, using single cell RNA-Seq, identified the most significantly affected molecular pathways during MM progression and provided a novel signature predictive of patient prognosis and treatment stratification.

Single cell sequencing reveals heterogeneity within ovarian cancer epithelium and cancer associated stromal cells

OBJECTIVES

The purpose of this study was to determine the level of heterogeneity in high grade serous ovarian cancer (HGSOC) by analyzing RNA expression in single epithelial and cancer associated stromal cells. In addition, we explored the possibility of identifying subgroups based on pathway activation and pre-defined signatures from cancer stem cells and chemo-resistant cells.

METHODS

A fresh, HGSOC tumor specimen derived from ovary was enzymatically digested and depleted of immune infiltrating cells. RNA sequencing was performed on 92 single cells and 66 of these single cell datasets passed quality control checks. Sequences were analyzed using multiple bioinformatics tools, including clustering, principle components analysis, and geneset enrichment analysis to identify subgroups and activated pathways. Immunohistochemistry for ovarian cancer, stem cell and stromal markers was performed on adjacent tumor sections.

RESULTS

Analysis of the gene expression patterns identified two major subsets of cells characterized by epithelial and stromal gene expression patterns. The epithelial group was characterized by proliferative genes including genes associated with oxidative phosphorylation and MYC activity, while the stromal group was characterized by increased expression of extracellular matrix (ECM) genes and genes associated with epithelial-to-mesenchymal transition (EMT). Neither group expressed a signature correlating with published chemo-resistant gene signatures, but many cells, predominantly in the stromal subgroup, expressed markers associated with cancer stem cells.

CONCLUSIONS

Single cell sequencing provides a means of identifying subpopulations of cancer cells within a single patient. Single cell sequence analysis may prove to be critical for understanding the etiology, progression and drug resistance in ovarian cancer.

A de novo splice site mutation in EHMT1 resulting in Kleefstra syndrome with pharmacogenomics screening and behavior therapy for regressive behaviors

Background

Kleefstra syndrome (KS) is a rare autosomal dominant developmental disability, caused by microdeletions or intragenic mutations within the epigenetic regulator gene EHMT1 (euchromatic histone lysine N‐methyltransferase 1). In addition to common features of autism, young adult regressive behaviors have been reported. However, the genetic downstream effects of the reported deletions or mutations on KS phenotype have not yet been completely explored. While genetic backgrounds affecting drug metabolism can have a profound effect on therapeutic interventions, pharmacogenomic variations are seldom considered in directing psychotropic therapies.

Methods

In this report, we used next‐generation sequencing (exome sequencing and high‐throughput RNA sequencing) in a patient and his parents to identify causative genetic variants followed by pharmacogenomics‐guided clinical decision‐making for making positive changes toward his treatment strategies. The patient had an early autism diagnosis and showed significant regressive behaviors and physical aberrations at age 23.

Results

Exome sequencing identified a novel, de novo splice site variant NM_024757.4: c.2750‐1G>T in EHMT1, a candidate gene for Kleefstra syndrome, in the patient that results in exon skipping and downstream frameshift and termination. Gene expression results from the patient showed, when compared to his parents, there was a significant decreased expression of several reported gene variants associated with autism risk. Further, using a pharmacogenomics genotyping panel, we discovered that the patient had the CYP2D6 nonfunctioning variant genotype *4/*4 that results in very low metabolic activity on a number of psychotropic drugs, including fluvoxamine which he was prescribed. As reported here, a change in psychotropic drugs and intense behavior therapies resulted in a significant reversal of the regressive behaviors and physical aberrations.

Conclusion

These results demonstrate an individualized approach that integrated genetic information and behavior therapies, resulting in a dramatic improvement in regressive behaviors associated with KS.

Abstract AS23: Microenvironment mediated downregulation of miR-193b promotes ovarian cancer metastasis

The cross-talk between ovarian cancer cells with the microenvironment of the site of metastasis is an essential determinant of successful metastatic colonization. microRNAs have been well established to play critical roles in various stages of cancer progression, including metastasis. However, the role of the signals from the microenvironment in regulating key microRNAs in metastasizing cancer cells has not been studied. Using a 3D culture model mimicking the human omentum, one of the principal sites of ovarian cancer metastasis, we have identified the microenvironment-induced downregulation of a tumor suppressor microRNA miR-193b in the metastasizing ovarian cancer cells. The direct interaction of the ovarian cancer cells with the mesothelial cells covering the surface of the omentum caused DNA methyltransferase 1 (DNMT1) mediated methylation and decreased expression of miR-193b. The reduction in miR-193b enabled the metastasizing cancer cells to invade and proliferate in the omentum both in vitro and in a mouse xenograft model of ovarian cancer metastasis. The functional effects of miR-193b were mediated at least partly through the concomitant increased expression of its target urokinase-type plasminogen activator (uPA). Our findings link paracrine signals from the microenvironment with the regulation of a key microRNA in cancer cells that is essential for the initial steps of ovarian cancer metastatic colonization. Targeting miR-193b would be a promising approach to treat ovarian cancer metastasis.

Citation Format: AK Mitra, CY Chiang, P Tiwari, ME Peter, E Lengyel. Microenvironment mediated downregulation of miR-193b promotes ovarian cancer metastasis [abstract]. In: Proceedings of the 10th Biennial Ovarian Cancer Research Symposium; Sep 8-9, 2014; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(16 Suppl):Abstract nr AS23.

Microenvironment-induced downregulation of miR-193b drives ovarian cancer metastasis

The cross-talk between ovarian cancer (OvCa) cells and the metastatic microenvironment is an essential determinant of successful colonization. Micro(mi)RNAs play several critical roles during metastasis; however, the role of microenvironmental cues in the regulation of miRNAs in metastasizing cancer cells has not been studied. Using a 3D culture model that mimics the human omentum, one of the principal sites of OvCa metastasis, we identified and characterized the microenvironment-induced downregulation of a tumor suppressor miRNA, miR-193b, in metastasizing OvCa cells. The direct interaction of the OvCa cells with mesothelial cells, which cover the surface of the omentum, caused a DNA methyltransferase 1 (DNMT1) mediated decrease in the expression of miR-193b. The reduction in miR-193b enabled the metastasizing cancer cells to invade and proliferate into human omental pieces ex vivo and into the omentum of a mouse xenograft model of OvCa metastasis. The functional effects of miR-193b were mediated, in large part, by the concomitant increased expression of its target, urokinase-type plasminogen activator (uPA), a known tumor-associated protease. These findings link paracrine signals from the microenvironment with the regulation of a key miRNA that is essential for the initial steps of OvCa metastatic colonization. Targeting miR-193b could prove effective in the treatment of OvCa metastasis.

A novel packing arrangement of AcrB in the lipid bilayer membrane

The central component AcrB of the Escherichia coli drug efflux complex AcrA-AcrB-TolC has been extensively investigated by X-ray crystallography of detergent-protein 3-D crystals. In these crystals, AcrB packs as trimers - the functional unit. We visualized the AcrB-AcrB interaction in its native environment by examining E. coli lipid reconstituted 2-D crystals, which were overwhelmingly formed by asymmetric trimers stabilized by strongly-interacting monomers from adjacent trimers. Most interestingly, we observed lattices formed by an arrangement of AcrB monomers distinct from that in traditional trimers. This hitherto unobserved packing, might play a role in the biogenesis of trimeric AcrB.

Exon 8-9 mutations of DNA polymerase β in ovarian carcinoma patients from Haldia, India

BACKGROUND

Ovarian cancer is the number one killer among all the gynecological cancers. We undertook association study to identify potential alterations in the genomic DNA of a DNA repair gene, DNA polymerase beta (polβ), involved in base excision repair (BER), in ovarian carcinomas of patients from Haldia, India. Mutations, splice variants have been reported earlier in different tumors other than ovarian tumors.

AIM

In this study we explored the possibility of association of any mutation of pol beta (Exon 8) with prognosis in 152 ovarian cancer samples.

RESULTS

Alteration in the exon 8 region (Exon 8:468, AgC; 15.1%) was noted among fifty seven polymorphism positive samples. Alteration in the intervening sequence 8 (IVS8, -25, AgC; 3.9%) was also noted. All alterations are heterozygous in nature.

CONCLUSIONS

We found no significant association among the samples from serous type, stage IV, and the polβ mutations (P ≤ 0.01). Only a slight tendency of association was evident between IVS8, -25, A to C; and stage III. Further analysis with a larger number of samples is needed.

Functional characterization of folate transport proteins in Staten's Seruminstitut rabbit corneal epithelial cell line

PURPOSE

The overall objective of this study was to investigate and characterize the expression of folate transport proteins in Staten's Seruminstitut rabbit corneal (SIRC) epithelial cell line.

METHODS

[(3)H]Folic acid uptake was studied with respect to time, pH, temperature, sodium, and chloride ion dependency. Inhibition studies were conducted with structural analogs, vitamins, and metabolic inhibitors. [(3)H]Folic acid uptake was also determined with varying concentrations of cold folic acid. Uptake kinetics was studied in the presence of various modulators of intracellular regulatory pathways, protein kinases A and C (PKA and PKC), protein tyrosine kinase (PTK), and calcium-calmodulin modulators. Ex vivo corneal permeability studies were carried out with [(3)H]folic acid in the presence and absence of 1 mM cold folic acid.

RESULTS

Linear increase in [(3)H]folic acid uptake was observed over 30 min. The process followed saturation kinetics with apparent K(m) of 14.2 ± 0.2 nM, V(max) of (1.5 ± 0.1)*10(-5) micro.moles/min/mg protein, and K(d) of (2.1 ± 0.2)*10(-6) min(-1). The uptake process was found to be dependent on pH, sodium ions, chloride ions, temperature, and energy. Uptake was inhibited in the presence of structural analogs (cold folic acid, methyltetrahydro folate, and methotrexate), but structurally unrelated vitamins did not show any effect. Membrane transport inhibitors SITS, DIDS, probenecid and endocytic inhibitor, colchicine significantly inhibited the [(3)H]folic acid uptake indicating the involvement of receptor/transporter mediated process. PKA, PTK, and Ca(2+)/calmodulin pathways significantly regulate the process. RT-PCR and Western blot analysis confirmed the presence of folate receptor-α (FR-alpha) and proton-coupled folate transporter (PCFT). Permeability of [(3)H]folic acid across the rabbit cornea was (1.48 ± 0.13)*10(-05) cm/sec, and in the presence of cold folic acid it was (1.08 ± 0.10)*10(-05) cm/sec.

CONCLUSIONS

This work demonstrated the functional and molecular presence of FR-alpha and PCFT in SIRC epithelial cell line.

Protective association exhibited by the single nucleotide polymorphism (SNP) rs1052133 in the gene human 8-oxoguanine DNA glycosylase (hOGG1) with the risk of squamous cell carcinomas of the head & neck (SCCHN) among north Indians

BACKGROUND & OBJECTIVES

Imbalances in compactly regulated DNA repair pathways in the form of single nucleotide polymorphisms (SNPs) within vital DNA repair genes may result in insufficient DNA repair and increase in DNA breaks thus rendering the human system vulnerable to the debilitatory effects of grave diseases like cancers. The present study involves investigation of association of the non-synonymous SNP rs1052133 (C8069G/Ser326Cys) located in the exonic region of the gene human 8-oxoguanine DNA glycosylase (hOGG1) with the risk of squamous cell carcinomas of the head and neck (SCCHN).

METHODS

Case-control based genetic association study was performed among 575 (250 SCCHN cases and 325 normal healthy controls) sub-population cluster-matched (Indo-Europeans linguistic subgroup + Caucasoid morphological subtype) samples from the north Indian States of Uttar Pradesh and Uttarakhand using polymerase chain reaction followed by restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing analysis.

RESULTS

Our results demonstrated statistically significant protective association for the heterozygous CG [Odds Ratio (OR) 0.6587, 95% Confidence Interval (CI) 0.4615 to 0.9402, P=0.0238], homozygous mutant GG (OR 0.2570, 95% CI 0.1070 to 0.6175, P=0.0013) and combined mutant CG + GG (OR 0.6057, 95% CI 0.4272 to 0.8586, P=0.0059) genotypes.

INTERPRETATION & CONCLUSIONS

The results indicate that the polymorphism rs1052133 is strongly associated with SCCHN susceptibility and the mutant (G) allele might be a protective factor for SCCHN among north Indian subpopulations.

Effect of high temperature and the presence of stone-wales defects on the mechanical behavior of a single wall carbon nanotube under tension and compression

On the basis of molecular dynamics simulation, a zigzag (7, 0) SWCNT is examined under axial tension and compression to observe its mechanical behavior and fracture pattern in the absence and presence of Stone-Wales (SW) defects coupled with the variation of temperature. A defect-free tube is subjected to tensile or compressive stresses at different temperatures. Then SW defects are introduced into it and stress is applied with the increase of temperature. The defective and defect-free tubes show different fracture patterns with increasing temperature showing significant changes in their mechanical properties. Compression of the tube also reveals interesting changes in its buckling behavior with variation of temperature and inclusion of defects.

Viral obesity: fact or fiction?

The aetiology of obesity is multifactorial. An understanding of the contributions of various causal factors is essential for the proper management of obesity. Although it is primarily thought of as a condition brought on by lifestyle choices, recent evidence shows there is a link between obesity and viral infections. Numerous animal models have documented an increased body weight and a number of physiologic changes, including increased insulin sensitivity, increased glucose uptake and decreased leptin secretion that contribute to an increase in body fat in adenovirus-36 infection. Other viral agents associated with increasing obesity in animals included canine distemper virus, rous-associated virus 7, scrapie, Borna disease virus, SMAM-1 and other adenoviruses. This review attempted to determine if viral infection is a possible cause of obesity. Also, this paper discussed mechanisms by which viruses might produce obesity. Based on the evidence presented in this paper, it can be concluded that a link between obesity and viral infections cannot be ruled out. Further epidemiologic studies are needed to establish a causal link between the two, and determine if these results can be used in future management and prevention of obesity.

Three-photon-induced four-photon absorption and nonlinear refraction in ZnO quantum dots

Three-photon-induced four-photon absorption via excited-state absorption and self-defocusing nonlinear refraction are reported for the first time, to our knowledge, in ZnO quantum dots with average sizes of 2.0+/-0.1 nm with 1064 nm radiation from a Q-switched Nd:YAG laser at a peak intensity of 2.5 GW/cm(2). By employing the three-level two-step model, the experimental results can be explained quite satisfactorily.

Conformational analysis of cyclo (L-cystine)

Conformational analysis of cyclo(L-cystine) shows that the diketopiperazine ring has to exist only in the boat form. With this geometry, the molecule can adopt two distinct forms differing mainly in the chirality of the disulphide bridge. In both the P- and M-models, corresponding to dihedral angles of nearly +90 degrees and -90 degrees respectively about the S-S- bond, the molecule displays an approximate two-fold symmetry. According to our semi-empirical energy calculations, the minimum energy of the M-model is --9.2 kcal/mol, only 0.3 kcal/mol lower than that of the P-model. Because the difference between the two minima is so small, neither form is clearly superior to the other. However, the number of low energy conformations of the M-model in the allowed conformational space is significantly larger than that of the P-model by a ratio of 3 to 1, and therefore the former is likely to be thermodynamically favoured.

Association of polymorphisms in base excision repair genes with the risk of breast cancer: a case-control study in North Indian women

Inheritance of common genetic variants at one or more base excision repair (BER) genes may result in a reduced DNA repair capacity and in an increased risk of cancers like breast cancer. The present case-control study with 390 north Indian women (155 breast cancer cases and 235 controls) was aimed to investigate the association of seven nonsynonymous BER gene polymorphisms viz. rs1130409/T1865G (APEX1), rs1799782/T22142C (XRCC1), rs25487/G23990A (XRCC1), rs4989588/T3337A (FEN1), rs4989586/ G3259A (FEN1), rs4989587/C3315T (FEN1), and rs1050525/G6941T (PCNA) with breast cancer susceptibility. Statistically significant association with breast cancer risk was observed for rs1130409 homozygous mutant GG [odds ratio (OR) 3.35, 95% confidence interval (CI) 1.36-8.26), heterozygous GT (OR 2.42, 95% CI 1.56-3.76), and combined mutant (GT + GG) (OR 2.52, 95% CI 1.65-3.86] genotypes and rs25487 homozygous mutant AA (OR 2.91, 95% CI 1.66-5.10) and combined mutant (AA + AG) (OR 1.41, 95% CI 0.903-2.19) genotypes, whereas protective association was exhibited by rs1799782 homozygous mutant CC (OR 0.413, 95% CI 0.082-2.08), heterozygous TC (OR 0.351, 95% CI 0.189-0.650), and combined mutant (TC + CC) (OR 0.357, 95% CI 0.199-0.641) genotypes. Association study using reconstructed haplotypes of XRCC1 gene showed positive association for the TA haplotype (OR 2.014, 95% CI 1.462-2.775) and a protective association for the CG haplotype (OR 0.173, 95% CI 0.052-0.576) pertaining to breast cancer risk. The results indicate that the polymorphisms rs1130409 (APEX1) and rs25487 (XRCC1) might be involved in contributing towards breast cancer susceptibility, while rs1799782 (XRCC1) might have protective influence.

EDXRF analysis of municipal solid waste using 109Cd source

Elemental compositions of municipal solid waste (MSW) samples have been analyzed using the non-destructive energy dispersive X-ray fluorescence (EDXRF) technique. The samples were collected from three different dumping sites of urban and suburban areas of the city of Kolkata, West Bengal, India. The EDXRF spectrometer consisted of a (109)Cd radioactive source and a Si (Li) detector. To check the reliability of the system, NIST Standard Reference Material-1648 UPM had been analyzed and it was found that within the experimental errors, our results agree quite well with the certified and non-certified values. The elemental compositions of all the three MSW samples were subsequently estimated using the same procedure. The matrix effects were estimated following the emission-transmission method. It was observed that except Fe, all the elements from Ti to Pb show concentration levels higher by a factor of 2-7 than the ecological screening values where as in the case of Fe, this factor varies from 100 to 200.

In stent restenosis: bane of the stent era

The long term outcome of stent implantation is affected by a process called in stent restenosis (ISR). Multiple contributory factors have been identified, but clear understanding of the overall underlying mechanism remains an enigma. ISR progresses through several different phases and involves numerous cellular and molecular constituents. Platelets and macrophages play a central role via vascular smooth muscle cell migration and proliferation in the intima to produce neointimal hyperplasia, which is pathognomic of ISR. Increased extracellular matrix formation appears to form the bulk of the neointimal hyperplasia tissue. Emerging evidence of the role of inflammatory cytokines and suppressors of cytokine signalling make this an exciting and novel field of antirestenosis research. Activation of Akt pathway triggered by mechanical stretch may also be a contributory factor to ISR formation. Prevention of ISR appears to be a multipronged attack as no therapeutic "magic bullet" exists to block all the processes in one go.

A comparison of stent-induced stenosis in coronary and peripheral arteries

BACKGROUND AND OBJECTIVES

Restenosis is a complication of interventional procedures such as angioplasty and stenting, often limiting the success of these procedures. Knowledge regarding the relative behaviour of different arteries after these procedures is limited, despite the extensive use of different vascular models. Although the results from studies using different vessels are analysed to predict the behaviour of coronary arteries and other vasculature, direct controlled comparisons between different arteries are necessary for a better understanding of the differential response to restenosis.

METHODS

This study examines the response to stenting in coronary and internal iliac arteries as characterised by intimal hyperplasia and restenosis. In a swine model of in-stent stenosis, coronary arteries exhibited higher levels of intimal hyperplasia and per cent stenosis than internal iliac arteries.

RESULTS

After normalisation for injury score, coronary arteries were found to undergo 47% more intimal hyperplasia (p<0.05), whereas per cent stenosis normalised for injury score tended to be higher (p = 0.01). Other measurements reflecting post-stenting intimal hyperplasia (maximal intimal thickness, medial area) did not exhibit significant differences between the artery groups.

CONCLUSIONS

These results show that coronary vessels are more prone to develop significant intimal hyperplasia and subsequent restenosis than internal iliac vessels. A better insight into how different arteries and arterial components behave is important in understanding and developing newer and better therapeutic measures for restenosis.

Comparing 2-year outcomes of anterior cruciate ligament reconstruction using either patella-tendon or semitendinosus-tendon autografts: a non-randomised prospective study

PURPOSE

To compare the results of anterior cruciate ligament (ACL) reconstructions using either a patella-tendon autograft or a semitendinosus-tendon autograft.

METHODS

Based on surgeon experience and preference, 68 patients underwent ACL reconstruction using either a quadruple-strand semitendinosus autograft (n = 34) or a central one-third bone-patella tendon-bone autograft (n = 34). Each patient was assessed preoperatively and postoperatively at 3, 6, and 24 months using the International Knee Documentation Committee (IKDC) knee score, Biodex muscle strength and endurance testing, and the KT1000 instrumented arthrometer test of knee laxity to anterior translation. All assessments at the 2-year follow-up were performed by the same physician and physiotherapist.

RESULTS

While ACL reconstruction improved knee stability and IKDC knee scores significantly, there was no statistically significant difference between semitendinosus- and patella-tendon autograft reconstructions in terms of long-term knee score or laxity to anterior translation. Semitendinosus graft reconstruction was associated with less donor-site morbidity and hamstring weakness. Meniscectomy was associated with poorer long-term knee scores.

CONCLUSION

ACL reconstruction is associated with a significantly better IKDC knee score and laxity measurement at 2-year follow-up. However, we were unable to demonstrate a significantly better long-term outcome in knee score or laxity to anterior translation with either a patella-tendon autograft or a semitendinosus-tendon autograft.

Assessment of blood-induced cartilage damage in rabbit knees using scanning electron microscopy

PURPOSE

To investigate the harmful effects of a single episode of intra-articular bleeding on articular cartilage of rabbit knees using scanning electron microscopy.

METHODS

Autologous blood was injected into the right knee joints of 18 New Zealand white rabbits. Surface and cellular damages were examined by the scanning electron microscope (n=9) and light microscope (n=34), respectively. The injected right knees were then compared with the corresponding control left knees at one, 3, and 6 weeks after the blood injection.

RESULTS

The articular surface of the injected knees turned uniformly rough with multiple pits after one week. Maximal changes with elevations and depressions were observed at 3 weeks. These changes reversed at 6 weeks with the irregularities smoothing out. A similar pattern of transient cartilage damage was noted histologically.

CONCLUSION

Both scanning electron microscopic and light microscopic findings suggest that a single episode of intra-articular bleeding leads to articular cartilage damage but this appears to be reversible. Our findings of transient damage to the articular cartilage suggest that there is no need for intra-articular evacuation and washout following an acute episode of haemarthrosis.

Arsenic concentrations in rice, vegetables, and fish in Bangladesh: a preliminary study

Arsenic contaminating groundwater in Bangladesh is one of the largest environmental health hazards in the world. Because of the potential risk to human health through consumption of agricultural produce grown in fields irrigated with arsenic contaminated water, we have determined the level of contamination in 100 samples of crop, vegetables and fresh water fish collected from three different regions in Bangladesh. Arsenic concentrations were determined by hydride generation atomic absorption spectrophotometry. All 11 samples of water and 18 samples of soil exceeded the expected limits of arsenic. No samples of rice grain (Oryza sativa L.) had arsenic concentrations more than the recommended limit of 1.0 mg/kg. However, rice plants, especially the roots had a significantly higher concentration of arsenic (2.4 mg/kg) compared to stem (0.73 mg/kg) and rice grains (0.14 mg/kg). Arsenic contents of vegetables varied; those exceeding the food safety limits included Kachu sak (Colocasia antiquorum) (0.09-3.99 mg/kg, n=9), potatoes (Solanum tuberisum) (0.07-1.36 mg/kg, n=5), and Kalmi sak (Ipomoea reptoms) (0.1-1.53 mg/kg, n=6). Lata fish (Ophicephalus punctatus) did not contain unacceptable levels of arsenic. These results indicate that arsenic contaminates some food items in Bangladesh. Further studies with larger samples are needed to demonstrate the extent of arsenic contamination of food in Bangladesh.

Morbidity following anterior cruciate ligament reconstruction using hamstring autograft

INTRODUCTION

As anterior cruciate ligament (ACL) reconstruction becomes more frequently performed, the expectation of earlier return to activities becomes higher; hence graft selection becomes more important. The use of hamstring tendon autograft is perceived to have less postoperative morbidities. We evaluate the early postoperative complications in this prospective study.

MATERIALS AND METHODS

Seventy-six patients operated by the same surgeon were assessed preoperatively, and 3 and 6 months after surgery. The hamstring and quadriceps strength were measured with Biodex machine and the side-to-side laxity measured using KT-1000 instrument. The patients were also assessed for their subjective complaints using IKDC (International Knee Documentation Committee) Knee Scoring System.

RESULTS

The strength and endurance index of the quadriceps and hamstrings recovered and improved by the sixth month after surgery. The recovery by the quadriceps muscle is more marked and by the sixth month, it has recovered to more than the preoperative level. As for laxity, the average side-to-side difference at 30 pounds was 2.75 mm by 6 months. Of these patients, the side-to-side difference was less than 5 mm in 66 patients (5 mm as taken to be acceptable for graft success). As for IKDC rating, at the sixth month, 71 patients had normal or near normal knee by their own assessment. No patients had anterior knee pain at rest. Sensory deficits were only present in 3 patients with complaints of numbness over the distribution of the saphenous nerve or its infrapatellar branch.

CONCLUSION

Most morbidities are temporal in nature and do not significantly affect the patient's activities.

The posterior cruciate ligament: an anthropometric study in Asians and evaluation of safe limits for bony tunnel creation during reconstruction

INTRODUCTION

Quantitative data regarding the dimensions of the posterior cruciate ligament (PCL) and its insertions have not been studied in Asians, and concerns have been raised regarding the danger of vascular injury when the bony tunnels are created during arthroscopically-assisted reconstruction.

MATERIALS AND METHODS

Ten male cadavers were used in this study, incorporating dissection and procedural arms. In the procedural arm, the path of the drill bit was tracked fluoroscopically as the tibial and femoral tunnels were created during simulated reconstructive surgery, and the effect of varying knee flexion angles was studied. Fluoroscopic images were analysed using specialised image processing software.

RESULTS

The mean length of the PCL at full extension was 37.7 +/- 1.9 mm, and the mean mid-substance width was 13.7 +/- 1.7 mm. The mean sagittal distance between the exit point of the tibial tunnel and the anterior surface of the popliteal artery, across all knee flexion positions, was merely 6.0 mm (range, 2.8 to 10.2 mm). This distance tended to increase with increasing knee flexion, but this was not statistically significant. The mean distance between the exit point of the femoral tunnel and the femoral artery was 51.1 mm (range, 42.1 to 59.0 mm).

CONCLUSIONS

The dimensions of the PCL and its insertions in Asians do not vary greatly from those reported for Western subjects. The distance from the exit point of the tibial tunnel to the popliteal artery is very small and, although this distance increases with increasing knee flexion, the improvement in the safety margin may neither be clinically nor statistically significant. The margin of safety for drilling of the femoral tunnel is much greater.

Caffeine ameliorates radiation-induced skin reactions in mice but does not influence tumour radiation response

Intramuscular administration of caffeine at a dose of 80 mg kg(-1) body weight to the gastrocnemius muscles of Swiss mice 5 min prior to local irradiation (35 Gy) of the leg delayed the progression of radiation-induced skin reactions in such animals. While 90% epilation with reddening of the skin was noted in animals treated with radiation alone, animals pretreated with caffeine suffered only partial hair loss with slight reddening of the skin on the 16th and 20th days post-irradiation. Beyond the 28th day, damage scores in irradiated feet for both the groups were similar (score 3) and remained unchanged until the 32nd day and then decreased and disappeared completely in both treatment groups by the 40th day after irradiation. In addition, the effect of caffeine on the radiation response of a mouse fibrosarcoma was investigated. Results showed that intratumoral administration of caffeine at a dose of 80 mg kg(-1) body weight 5 min prior to local exposure of tumours to 10 Gy of 60Co gamma-rays did not influence the response of tumours to radiation. The present study thus showed that although caffeine ameliorated radiation-induced skin reactions in the mouse leg, it did not affect the tumour radiation response, indicating its potential application in cancer radiotherapy.

Time-dependent loss of radioactivity counts associated with paracellular markers in the presence of cyclodextrin

This communication reports an unexpected phenomenon observed during the counting of radiolabeled paracellular marker solutions in the presence of 2-hydroxypropyl-beta-cyclodextrin (HPbetaCD). The results revealed time-dependent loss of 14C-mannitol and 14C-polyethlene glycol 4000 radioactivity counts with increased percentages of HPbetaCD. However, 14C-diazepam, a transcellular marker, displayed a stable count. A hypothesis behind this phenomenon is being proposed, involving water transfer from aqueous droplets to the surfactant rich scintillation fluid. The remaining droplets, becoming more and more concentrated in cyclodextrin, entrap the hydrophilic markers and consequently exhibit an increasing quenching effect. This effect shows that careful monitoring of radiolabeled markers used in transport experiments is necessary, even with high quench resistant scintillation fluids, to prevent erroneous interpretation of the transport data.

Intestinal absorption and biodistribution of cosalane and its amino acid conjugates: novel anti-HIV agents

Cosalane and its amino acid conjugates are potent inhibitors of HIV replication. The purpose of this study was to investigate: (1) the pharmacokinetic disposition of the diglycine (GC) and the diaspartic acid (ASPC) conjugates of cosalane in male Sprague-Dawley rats; (2) intestinal absorption of cosalane and its amino acid conjugates using in vitro (small intestinal segments), in situ (closed loop); and (3) biodistribution of GC and its absolute oral bioavailability in rat. Cosalane and its conjugates exhibited biexponential disposition with very long half-lives upon intravenous dosing. However, these compounds failed to permeate the small intestine unless sodium desoxycholate (5-20 mM) was used as an intestinal permeation enhancer. A rank order correlation in terms of permeation enhancement in a descending order is as follows: GC>Cosalane>ASPC. In situ studies revealed that although the bile salt enhanced the permeation of cosalane across the enterocyte, its hepatic uptake was extensive. However, 66% of the absorbed dose of GC escaped uptake by the reticuloendothelial system (RES) and its biodistribution studies showed that the uptake by the RES was significantly lower compared to the parent compound. GC had an absolute oral bioavailability of 5.10+/-1.51%. Therefore, GC appears to be a favorable candidate for further development.

Hyperimmune bovine colostrum in the treatment of shigellosis in children: a double-blind, randomized, controlled trial

Immunological approaches have been considered as an alternative therapeutic option for the treatment of enteric infections over the past few years. Hyperimmune bovine colostrum (HBC) is a potentially innovative immunological option in the management of shigellosis together with traditional antibiotic therapy. Children aged 1-12 y with a history of bloody mucoid diarrhoea of less than 5 d duration were enrolled after their stool specimen was found to be positive for Shigella dysenteriae type I antigen by a rapid diagnostic fluorescent antibody staining test. They were randomized to receive either HBC containing very high titres of antibody against S. dysenteriae type I antigen or bovine colostrum (BC) without any antibody. The study group received 100 ml of HBC three times a day orally for 3 d and control group received BC. Children also received pivmecillinam in a dose of 50 mg kg(-1) d(-1) in four divided doses orally for 5 d. Admission characteristics of the 34 children in the HBC group and 35 in the BC group were comparable. No significant differences were observed in duration of diarrhoea, fever, anorexia, abdominal pain, tenesmus, stool frequency or visible blood in the stool between the groups. Two (6%) children in the study and five (14%) in the control group remained stool culture positive for S. dysenteriae type 1, even after 5 d of sensitive antimicrobial therapy.

CONCLUSION

The results indicate that HBC as an adjuvant is unable to show any beneficial effect in reducing the stool frequency, duration or severity of childhood shigellosis due to S. dysenteriae type I infection.

Strategies to overcome simultaneous P-glycoprotein mediated efflux and CYP3A4 mediated metabolism of drugs

Cytochrome P450 3A4 (CYP3A4), abundant in both the liver and upper intestinal enterocytes, limits the systemic bioavailability of xenobiotics. P-glycoprotein (P-gp), the MDR1 gene product, is also known to reduce the oral bioavailability of the drug molecules. High cellular expression of P-gp and CYP3A4 in mature intestinal enterocytes and their similar substrate specificity suggest that the function of these proteins may be complementary and may form a co-ordinated intestinal barrier. Various ongoing preclinical and clinical studies have demonstrated that the oral bioavailability of various P-gp and/or CYP3A4 substrates can be increased by simultaneous administration of P-gp and/or CYP3A4 inactivators. The current review describes the background and summarises several proposed hypotheses in modifying oral bioavailability by various drug-inhibitor interactions.

Transport of acyclovir ester prodrugs through rabbit cornea and SIRC-rabbit corneal epithelial cell line

The purpose of this study is to assess the permeability of acyclovir (ACV) prodrugs through the rabbit corneal cell line (SIRC) as well as the cornea, and characterize the SIRC cell line for transport and metabolism studies of ester prodrugs. Prodrug derivatization of an acycloguanosine antiviral agent, acyclovir, was employed to improve its permeability across the cornea. New Zealand albino rabbits were used as an animal model for corneal studies. The SIRC cell line grown on polyester membranes was used for transport of these prodrugs. SIRC cells grown on the membrane support for 10 days developed four to six layers of epithelial cells, and this is comparable to the normal rabbit corneal epithelial layer. Transport experiments were conducted across the rabbit cornea and confluent SIRC cells using side-by-side diffusion-cell apparatus. Enzymatic hydrolysis of these compounds was evaluated in SIRC cell lysates. Appropriate reversed phase HPLC method(s) were employed for quantitation of both the prodrug and ACV simultaneously. Corneal permeabilities of some of these prodrugs (Malonyl ACV and Acetyl ACV) were higher relative to ACV. The SIRC cell line permeability values of all the prodrugs were higher compared to that of the intact cornea. The total amount of ACV-prodrugs transported, i.e., unhydrolyzed prodrugs and regenerated ACV, across the SIRC cell line was more relative to ACV. Hydrolytic studies in the SIRC cell line homogenate demonstrated the bioreversion potential of the prodrugs and the presence of enzymes, particularly the cholinesterase in the SIRC cell line. It may be concluded that the SIRC cell line is leakier compared to the cornea. Keeping in mind the limitations, the SIRC cell line after further characterization may be used for transport and metabolism studies of ester prodrugs.