Evolution of cisplatin resistance through coordinated metabolic reprogramming of the cellular reductive state

BACKGROUND

Cisplatin (CDDP) is a mainstay treatment for advanced head and neck squamous cell carcinomas (HNSCC) despite a high frequency of innate and acquired resistance. We hypothesised that tumours acquire CDDP resistance through an enhanced reductive state dependent on metabolic rewiring.

METHODS

To validate this model and understand how an adaptive metabolic programme might be imprinted, we performed an integrated analysis of CDDP-resistant HNSCC clones from multiple genomic backgrounds by whole-exome sequencing, RNA-seq, mass spectrometry, steady state and flux metabolomics.

RESULTS

Inactivating KEAP1 mutations or reductions in KEAP1 RNA correlated with Nrf2 activation in CDDP-resistant cells, which functionally contributed to resistance. Proteomics identified elevation of downstream Nrf2 targets and the enrichment of enzymes involved in generation of biomass and reducing equivalents, metabolism of glucose, glutathione, NAD(P), and oxoacids. This was accompanied by biochemical and metabolic evidence of an enhanced reductive state dependent on coordinated glucose and glutamine catabolism, associated with reduced energy production and proliferation, despite normal mitochondrial structure and function.

CONCLUSIONS

Our analysis identified coordinated metabolic changes associated with CDDP resistance that may provide new therapeutic avenues through targeting of these convergent pathways.

Glutathione peroxidase 2 is a metabolic driver of the tumor immune microenvironment and immune checkpoint inhibitor response

BACKGROUND

The existence of immunologically 'cold tumors' frequently found across a wide spectrum of tumor types represents a significant challenge for cancer immunotherapy. Cold tumors have poor baseline pan-leukocyte infiltration, including a low prevalence of cytotoxic lymphocytes, and not surprisingly respond unfavorably to immune checkpoint (IC) inhibitors. We hypothesized that cold tumors harbor a mechanism of immune escape upstream and independent of ICs that may be driven by tumor biology rather than differences in mutational neoantigen burden.

METHODS

Using a bioinformatic approach to analyze TCGA (The Cancer Genome Atlas) RNA sequencing data we identified genes upregulated in cold versus hot tumors across four different smoking-related cancers, including squamous carcinomas from the oral cavity (OCSCC) and lung (LUSC), and adenocarcinomas of the bladder (BLCA) and lung (LUAD). Biological significance of the gene most robustly associated with a cold tumor phenotype across all four tumor types, glutathione peroxidase 2 (GPX2), was further evaluated using a combination of in silico analyses and functional genomic experiments performed both in vitro and in in vivo with preclinical models of oral cancer.

RESULTS

Elevated RNA expression of five metabolic enzymes including GPX2, aldo-keto reductase family 1 members AKR1C1, AKR1C3, and cytochrome monoxygenases (CP4F11 and CYP4F3) co-occurred in cold tumors across all four smoking-related cancers. These genes have all been linked to negative regulation of arachidonic acid metabolism-a well-established inflammatory pathway-and are also known downstream targets of the redox sensitive Nrf2 transcription factor pathway. In OCSCC, LUSC, and LUAD, GPX2 expression was highly correlated with Nrf2 activation signatures, also elevated in cold tumors. In BLCA, however, GPX2 correlated more strongly than Nrf2 signatures with decreased infiltration of multiple leukocyte subtypes. GPX2 inversely correlated with expression of multiple pro- inflammatory cytokines/chemokines and NF-kB activation in cell lines and knockdown of GPX2 led to increased secretion of prostaglandin E2 (PGE2) and interleukin-6. Conversely, GPX2 overexpression led to reduced PGE2 production in a murine OCSCC model (MOC1). GPX2 overexpressing MOC1 tumors had a more suppressive tumor immune microenvironment and responded less favorably to anti-cytotoxic T-lymphocytes-associated protein 4 IC therapy in mice.

CONCLUSION

GPX2 overexpression represents a novel potentially targetable effector of immune escape in cold tumors.

Impact of Climate Change and Land Use on Groundwater Salinization in Southern Bangladesh-Implications for Other Asian Deltas

Pervasive salinity in soil and water is affecting agricultural yield and the health of millions of delta dwellers in Asia. This is also being exacerbated by climate change through increases in sea level and tropical storm surges. One consequence of this has been a widespread introduction of salt water shrimp farming. Here, we show, using field data and modeling, how changes in climate and land use are likely to result in increased salinization of shallow groundwater in SE Asian mega-deltas. We also explore possible adaptation options. We find that possible future increase of episodic inundation events, combined with salt water shrimp farming, will cause rapid salinization of groundwater in the region making it less suitable for drinking water and irrigation. However, modified land use and water management practices can mitigate the impacts on groundwater, as well as the overlying soil, from future salinization. The study therefore provides guidance for adaptation planning to reduce future salinization in Asian deltas.

Human and livestock waste as a reduced carbon source contributing to the release of arsenic to shallow Bangladesh groundwater

Recent studies have demonstrated that the supply of relatively young organic carbon stimulates the release of arsenic to groundwater in Bangladesh. This study explores the potential role of human and livestock waste as a significant source of this carbon in a densely populated rural area with limited sanitation. Profiles of aquifer sediment samples were analyzed for phytosterols and coprostanol to assess the relative contributions of plant-derived and human/livestock waste-derived organic carbon at two well-characterized sites in Araihazar. Coprostanol concentrations increased with depth from non-detection (<10m at Site B and <23m at Site F) to maxima of 1.3 and 0.5ng/g in aquifer sands recovered from 17m (Site B) and 26m (Site F), respectively. The commonly used sewage contamination index ([5β-coprostanol]/([5α-cholestanol]+[5β-coprostanol])) exceeds 0.7 between 12 and 19m at Site B and between 24 and 26m at Site F, indicating input of human/livestock waste to these depths. Urine/fecal input within the same depth range is supported by groundwater Cl/Br mass ratios >1000 compared to Cl/Br <500 at depths >50m. Installed tube wells in the area's study sites may act as a conduit for DOC and specifically human/livestock waste into the aquifer during flood events. The depth range of maximum input of human/livestock waste indicated by these independent markers coincides with the highest dissolved Fe (10-20mg/L) and As (200-400μg/L) concentrations in groundwater at both sites. The new findings suggest that the oxidation of human/livestock waste coupled to the reductive dissolution of iron-(oxy)-hydroxides and/or arsenate may enhance groundwater contamination with As.

Microhomology-mediated end joining is activated in irradiated human cells due to phosphorylation-dependent formation of the XRCC1 repair complex

Microhomology-mediated end joining (MMEJ), an error-prone pathway for DNA double-strand break (DSB) repair, is implicated in genomic rearrangement and oncogenic transformation; however, its contribution to repair of radiation-induced DSBs has not been characterized. We used recircularization of a linearized plasmid with 3΄-P-blocked termini, mimicking those at X-ray-induced strand breaks, to recapitulate DSB repair via MMEJ or nonhomologous end-joining (NHEJ). Sequence analysis of the circularized plasmids allowed measurement of relative activity of MMEJ versus NHEJ. While we predictably observed NHEJ to be the predominant pathway for DSB repair in our assay, MMEJ was significantly enhanced in preirradiated cells, independent of their radiation-induced arrest in the G2/M phase. MMEJ activation was dependent on XRCC1 phosphorylation by casein kinase 2 (CK2), enhancing XRCC1's interaction with the end resection enzymes MRE11 and CtIP. Both endonuclease and exonuclease activities of MRE11 were required for MMEJ, as has been observed for homology-directed DSB repair (HDR). Furthermore, the XRCC1 co-immunoprecipitate complex (IP) displayed MMEJ activity in vitro, which was significantly elevated after irradiation. Our studies thus suggest that radiation-mediated enhancement of MMEJ in cells surviving radiation therapy may contribute to their radioresistance and could be therapeutically targeted.

Terrestrial water load and groundwater fluctuation in the Bengal Basin

Groundwater-level fluctuations represent hydraulic responses to changes in groundwater storage due to aquifer recharge and drainage as well as to changes in stress that include water mass loading and unloading above the aquifer surface. The latter 'poroelastic' response of confined aquifers is a well-established phenomenon which has been demonstrated in diverse hydrogeological environments but is frequently ignored in assessments of groundwater resources. Here we present high-frequency groundwater measurements over a twelve-month period from the tropical, fluvio-deltaic Bengal Aquifer System (BAS), the largest aquifer in south Asia. The groundwater level fluctuations are dominated by the aquifer poroelastic response to changes in terrestrial water loading by processes acting over periods ranging from hours to months; the effects of groundwater flow are subordinate. Our measurements represent the first direct, quantitative identification of loading effects on groundwater levels in the BAS. Our analysis highlights the potential limitations of hydrogeological analyses which ignore loading effects in this environment. We also demonstrate the potential for employing poroelastic responses in the BAS and across other tropical fluvio-deltaic regions as a direct, in-situ measure of changes in terrestrial water storage to complement analyses from the Gravity and Climate Experiment (GRACE) mission but at much higher resolution.

Evidence for Elevated Levels of Arsenic in Public Wells of Bangladesh Due To Improper Installation

One of the mainstays of mitigation to reduce the exposure of the rural population of Bangladesh to arsenic (As) from private, mostly <90-m deep wells over the past 15 years has been the installation of over 300,000 deeper community wells. A comprehensive testing campaign previously conducted across a 180 km² of area of Bangladesh identified 9 out of total of 927 wells >90 m deep that contained >50 µg/L arsenic. We show here that for five of these nine wells, conductivity profiles obtained after spiking the well bore with salt indicate a shallow leak that could explain the high As in the well water. In two of the five leaky wells, the presence of additional screens at the depth of the leak was documented with a downhole camera. The downhole camera did not detect anomalies in the construction of the remaining three leaky wells or in the four wells that did not leak. The four wells that did not leak were all >150-m deep and located in two villages separated by less than 500 m. Excluding these two villages and a handful of leaky wells, the results indicate an aquifer that is consistently low in As over a sizeable area at depths >90 m. Isolated cases of public wells that are elevated in As that have been reported elsewhere in Bangladesh may therefore reflect improper installation rather than actual contamination of the deep aquifer.

Reactive transport modeling of subsurface arsenic removal systems in rural Bangladesh

Subsurface Arsenic Removal (SAR) is a technique for in-situ removal of arsenic from groundwater. Extracted groundwater is aerated and re-injected into an anoxic aquifer, where the oxygen in the injected water reacts with ferrous iron in the aquifer to form hydrous ferric oxide (HFO). Subsequent extraction of groundwater contains temporarily lower As concentrations, because As sorbs onto the HFO. Injection, storage, and extraction together is called a cycle. A reactive transport model (RTM) was developed in PHREEQC to determine the hydrogeochemical processes responsible for As (im)mobilization during experimental SAR operation performed in Bangladesh. Oxidation of Fe(II) and As(III) were modeled using kinetic-rate expressions. Cation exchange, precipitation of HFO, and surface complexation, were modeled as equilibrium processes. A best set of surface complexation reactions and corresponding equilibrium constants was adopted from previous studies to simulate all 20 cycles of a SAR experiment. The model gives a reasonable match with observed concentrations of different elements in the extracted water (e.g., the r(2) value of As was 0.59 or higher). As concentrations in the extracted water are governed by four major processes. First, As concentration decreases in response to the elevated pH of injection water and likewise increases when native neutral pH groundwater flows in. Second, the sorption capacity for As increases due to the gradual buildup of HFO. Third, As sorption is enhanced by preferential removal of As(V). Fourth, competitive sorption of Si limits the capacity of freshly precipitated HFO for As sorption. Transferability of the developed reactive transport model was demonstrated through successful application of the model, without further calibration, to two additional SAR sites in Bangladesh. This gives confidence that the model could be useful to assess potential SAR performance at locations in Bangladesh based on local hydrogeochemical conditions.

A review of arsenic and its impacts in groundwater of the Ganges-Brahmaputra-Meghna delta, Bangladesh

Arsenic in drinking water is the single most important environmental issue facing Bangladesh; between 35 and 77 million of its 156 million inhabitants are considered to be at risk from drinking As-contaminated water. This dominates the list of stress factors affecting health, livelihoods and the ecosystem of the delta region. There is a vast literature on the subject so this review provides a filter of the more important information available on the topic. The arsenic problem arises from the move in the 1980s and 1990s by international agencies to construct tube wells as a source of water free of pathogens, groundwater usually considered a safe source. Since arsenic was not measured during routine chemical analysis and also is difficult to measure at low concentrations it was not until the late 1990s that the widespread natural anomaly of high arsenic was discovered and confirmed. The problem was exacerbated by the fact that the medical evidence of arsenicosis only appears slowly. The problem arises in delta regions because of the young age of the sediments deposited by the GBM river system. The sediments contain minerals such as biotite which undergo slow "diagenetic" reactions as the sediments become compacted, and which, under the reducing conditions of the groundwater, release in the form of toxic As(3+). The problem is restricted to sediments of Holocene age and groundwater of a certain depth (mainly 30-150 m), coinciding with the optimum well depth. The problem is most serious in a belt across southern Bangladesh, but within 50 m of the coast the problem is only minor because of use of deep groundwater; salinity in shallow groundwater here is the main issue for drinking water. The Government of Bangladesh adopted a National Arsenic Policy and Mitigation Action Plan in 2004 for providing arsenic safe water to all the exposed population, to provide medical care for those who have visible symptoms of arsenicosis. There is as yet no national monitoring program in place. Various mitigation strategies have been tested, but generally the numerous small scale technological remedies have proved unworkable at village level. The current statistics show that use of deep groundwater (below 150 m) is the main source of arsenic mitigation over most of the arsenic affected areas as well as rainwater harvesting in certain location.

NF-κB regulates radioresistance mediated by β1-integrin in three-dimensional culture of breast cancer cells

β1-integrin induction enhances breast cancer cell survival after exposure to ionizing radiation (IR), but the mechanisms of this effect remain unclear. Although NF-κB initiates prosurvival signaling pathways post-IR, the molecular function of NF-κB with other key elements in radioresistance, particularly with respect to extracellular matrix-induced signaling, is not known. We discovered a typical NF-κB-binding site in the β1-integrin promoter region, indicating a possible regulatory role for NF-κB. Using three-dimensional laminin-rich extracellular matrix (3D lrECM) culture, we show that NF-κB is required for β1-integrin transactivation in T4-2 breast cancer cells post-IR. Inhibition of NF-κB reduced clonogenic survival and induced apoptosis and cytostasis in formed tumor colonies. In addition, T4-2 tumors with inhibition of NF-κB activity exhibit decreased growth in athymic mice, which was further reduced by IR with downregulated β1-integrin expression. Direct interactions between β1-integrin and NF-κB p65 were induced in nonmalignant breast epithelial cells, but not in malignant cells, indicating context-specific regulation. As β1-integrin also activates NF-κB, our findings reveal a novel forward feedback pathway that could be targeted to enhance therapy.

Abstract P1-05-08: Targeting integrin signaling suppresses invasive recurrence in a three-dimensional model of radiation treated ductal carcinoma in situ

Background: DCIS (ductal carcinoma in situ) is comprised of cancerous cells that are contained within the milk duct and separated from the stroma by a basement membrane. Akt activation is implicated in breast cancer progression and also upregulated in ∼30% of DCIS lesions. We have previously shown that β1-integrin inhibition enhanced the efficacy of ionizing radiation (IR) in invasive breast cancer, via an Akt-mediated effect. Radiation therapy (RT) is commonly used to treat DCIS, resulting in a decrease in recurrence risk by ∼50%. However, DCIS still recurs in a substantial number of patients, and as invasive disease half of the time. This study aimed to identify the effects of IR on Akt-driven DCIS, and possible mechanisms underlying invasive progression in surviving cells.

Materials and Methods: To model DCIS, we took advantage of the ability of non-invasive mammary epithelial cells, MCF10A that form duct-like structures in 3-dimensional laminin-rich extracellular matrix (3D lrECM), and overexpressed an activated myristoylated form of the serine/threonine kinase, Akt. The 3D lrECM cultured MCF10A-Akt cells show filled lumen and retained basal polarity, characteristic of DCIS lesions in vivo. After DCIS structures formed in 3D lrECM, cultures were exposed to 8 Gy IR. Confocal microscopy analysis, western blot analysis, matrigel chemoinvasion assay and matix degradation assay were performed to characterize the IR effect on luminal or basal cells of the DCIS like structures.

Results: MCF10A-Akt structures post-8 Gy IR shows a significant increase in apoptosis measured by cleaved caspase-3 (n = 3, P &lt; 0.05). When we propagated cells post-IR in 3D lrECM, an invasive phenotype emerged in a sub-population of survivors (n = 3, P &lt; 0.01). We also confirmed that inhibitory antibodies to β1-integrin suppressed the invasive phenotype that was induced by 8 Gy IR. In addition to this, invasion activity emerged by 8 Gy IR was inhibited by nuclear factor-kappaB (NF-κB) inhibitor JSH-23 (n = 3, P &lt; 0.01). Finally, inhibition of β1-integrins or NF-κB translocation completely suppresses the formation of invasive colonies.

Discussion: In present study, we found that inhibition of β1-integrins abrogates the emergence of an invasive phenotype among surviving clones. Our current data suggest that regulation of β1-integrin signaling via NF-κB plays an important role in the emergence of invasive disease after radiation, and may be an important clinical target.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-05-08.

Abstract P4-06-05: NF-κB Upregulates β1-integrin via Increased Transcriptional Activity in Three-dimensional Culture: a Mechanism by which Malignant Breast Cells Acquire Radioresistance

The molecular mechanisms giving rise to tumor viability after therapeutic radiation remain elusive. We showed previously that β1-integrin is associated with enhanced cell survival of breast cancer cells after exposure to high dose ionizing radiation (IR). Recently, we discovered that a typical binding site for Nuclear factor-κB (NF-κB), a stress-sensitive heterodimeric transcription factor, was located in human β1-integrin promoter, which indicates that β1-integrin-mediated resistance to radiation may be functionally regulated by NF-κB. The aim of the present study was to investigate the relationship between NF-κB and β1-integrin pathways in radioprotection of malignant T4-2 breast cells in three-dimensional laminin-rich extracellular matrix (3D lrECM). We show that NF-κB is required for radiation-induced β1-integrin transactivation. Inhibition of NF-κB activity significantly reduced clonogenic survival with the inhibition of IR-induced total and phosphorylated (Thr 788/789) β1-integrins, correlated with increased DNA binding activity at the β1- integrin promoter. Treatment of T4-2 colonies with NF-κB activation inhibitor before IR resulted in a reduction of the size of colonies, associated with a decrease in proliferation and increase in apoptosis, indicating an increased susceptibility to IR. Further studies revealed that a direct interaction of β1-integrin with α5-integrin was highly induced, but not with NF-κB p65, in T4-2 cells surviving IR. These interactions were found to be oppositely regulated in radiosensitive S1 cells, suggesting that IR induces the formation of α5β1-integrin complexes leading to increased survival post-IR. Together these results provide the first evidence that NF-κB-induced β1-integrin transactivation is responsible for increased survival post IR in breast cancer. Since β1-integrin is shown to activate NF-κB, our data further suggest a loop-like β1-integrin–NF-κB–β1-integrin pathway in tumor radioresistance. This novel pathway may serve as an efficient drug target to re-sensitize radioresistant tumor cells.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-06-05.

Growth performance and nutrient composition of juvenile Nile tilapia (Oreochromis niloticus) fed Spirulina flakes, rice bran and mustard oil cake

INTRODUCTION

Tilapia (Oreochromis niloticus) is an important cultured fish that is widely distributed in Bangladesh. This study was conducted to improve the growth performance and nutrient contents of the fish using five different types of feeds.

METHODS

Tilapia fingerlings were fed two types of commercial fish feeds (Feed-1 and Feed-2), Spirulina flakes (Feed-3), Feed-2 mixed with Spirulina flakes (Feed-4) and manually mixed feed made from a mixture of mustard oil cake and rice bran (Feed-5). After 4 weeks of being fed with the diets, growth parameters and meat nutrient composition of the tilapia fingerlings were recorded.

RESULTS

Significant growth in length and weight was observed in juvenile tilapia fish fed with commercial Feed-1 only, while growth performance varied significantly among fingerlings fed other types of feeds. Body tissue calcium (92.8 mg/100 g), iron (1.29 mg/100 g) was higher in fishes fed with dry Spirulina flakes (Feed 3), while the highest amount of zinc (2.09 mg/100 g) was recorded in fishes fed Feed-5. Protein (13.32%) content was highest in fish fed Feed-2 mixed with Spirulina flakes (Feed-4).

CONCLUSION

Meat nutritional quality of tilapia can be improved by combining commercial feeds with Spirulina flakes, compared with feeding commercial feeds in isolation.

P3-01-06: NF-kB Inhibition Promotes Radiosensitivity of Breast Cancer Cells in Three-Dimensional Culture through Abating b1-Integrin Expression

Therapy-associated tumor resistance, giving rise to recurrence and mortality, is a critical issue in cancer therapy. The molecular mechanisms causing tumor resistnace to the therapeutic radiation remain elusive. Nuclear factor-KB (NF-KB), a stress-sensitive heterodimeric transcription factor in the regulation of the stress-responsive genes, has been shown to initiate prosurvival signaling pathways. The cooperative function of NF-KB with other key stress elements in radioresistance remains to be elucidated. We have previously reported that induction of α5β1-integrin is associated with the enhanced cell survival of breast cancer cells after exposure to high dose IR (ionizing radiation). Because a typical NF-KB binding site was located in human β1-integrin promoter region, β1-integrin-mediated resistance to radiation may be regulated by NF-KB. The aim of the present study was to reveal a connection between NF-KB and β1-integrin pathways in radioprotection of malignant T4-2 mammary epithelial cells in 3D ***lrECM (three-dimensional laminin-rich extracellular matrix). We show that the elevated NF-KB activity was correlated with enhanced clonogenic survival, and increased NF-KB heterodimer p50/p65 levels were associated with an increase in total and phosphorylated (Thr 788/789) β1-integrins. Inhibition of NF-KB activation significantly reduced clonogenic survival with the inhibition of β1-integrin. These results indicate that NF-KB-mediated induction of β1-integrin is associated with an increased radiation resistance. Treatment of T4-2 colonies, formed at day 4, with NF-KB activation inhibitor in 3D lrECM before exposure to IR (4-Gy X-ray) resulted in a reduction of the size of colonies. The surviving colonies were associated with a decrease in proliferation and increase in apoptosis, indicating a decrease of resistance to IR. Together, these results provide the first evidence that NF-KB-mediated β1-integrin expression is responsible for tumor radioresistance. The NF-KB/β1-integrin pathway may serve as an efficient drug target to re-sensitize radioresistant tumor cells.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-01-06.

Arsenic migration to deep groundwater in Bangladesh influenced by adsorption and water demand

Drinking shallow groundwater with naturally elevated concentrations of arsenic is causing widespread disease in many parts of South and Southeast Asia. In the Bengal Basin, growing reliance on deep (>150 m) groundwater has lowered exposure. In the most affected districts of Bangladesh, shallow groundwater concentrations average 100 to 370 μg L(-1), while deep groundwater is typically < 10 μg L(-1). Groundwater flow simulations have suggested that, even when deep pumping is restricted to domestic use, deep groundwater in some areas of the Bengal Basin is at risk of contamination. However, these simulations have neglected the impedance of As migration by adsorption to aquifer sediments. Here we quantify for the first time As sorption on deeper sediments in situ by replicating the intrusion of shallow groundwater through injection of 1,000 L of deep groundwater modified with 200 μg L(-1) of As into a deeper aquifer. Arsenic concentrations in the injected water were reduced by 70% due to adsorption within a single day. Basin-scale modelling indicates that while As adsorption extends the sustainable use of deep groundwater, some areas remain vulnerable; these areas can be prioritized for management and monitoring.

Temporal variations in arsenic uptake by rice plants in Bangladesh: the role of iron plaque in paddy fields irrigated with groundwater

The transfer of arsenic to rice grains is a human health issue of growing relevance in regions of southern Asia where shallow groundwater used for irrigation of paddy fields is elevated in As. In the present study, As and Fe concentrations in soil water and in the roots of rice plants, primarily the Fe plaque surrounding the roots, were monitored during the 4-month growing season at two sites irrigated with groundwater containing approximately 130microgl(-1) As and two control sites irrigated with water containing <15microgl(-1) As. At both sites irrigated with contaminated water, As concentrations in soil water increased from <10microgl(-1) to >1000microgl(-1) during the first five weeks of the growth season and then gradually declined to <10microgl(-1) during the last five weeks. At the two control sites, concentrations of As in soil water never exceeded 40microgl(-1). At both contaminated sites, the As content of roots and Fe plaque rose to 1000-1500mgkg(-1) towards the middle of the growth season. It then declined to approximately 300mgkg(-1) towards the end, a level still well above As concentration of approximately 100mgkg(-1) in roots and plaque measured throughout the growing season at the two control sites. These time series, combined with simple mass balance considerations, demonstrate that the formation of Fe plaque on the roots of rice plants by micro-aeration significantly limits the uptake of As by rice plants grown in paddy fields. Large variations in the As and Fe content of plant stems at two of the sites irrigated with contaminated water and one of the control sites were also recorded. The origin of these variations, particularly during the last month of the growth season, needs to be better understood because they are likely to influence the uptake of As in rice grains.

Derepression of HMGA2 via removal of ZBRK1/BRCA1/CtIP complex enhances mammary tumorigenesis

The high mobility group AT-hook 2 (HMGA2), a DNA architectural protein, is highly regulated during development and plays an important role in tumorigenesis. Indeed, HMGA2 was overexpressed in many different kinds of tumors. However, the mechanisms regulating HMGA2 expression remain elusive. Using microarray analysis, we found that HMGA2, along with a dozen of other genes, was co-repressed by ZBRK1, BRCA1, and CtIP. BRCA1 exerts its transcriptional repression activity through interaction with the transcriptional repressor ZBRK1 in the central domain, and with CtIP in the C-terminal BRCT domain. Here, we show that ZBRK1, BRCA1, and CtIP form a repression complex that coordinately regulates HMGA2 expression via a ZBRK1 recognition site in the HMGA2 promoter. Depletion of any of the proteins in this complex via adenoviral RNA interference in MCF10A mammary epithelial cells activates HMGA2 expression, resulting in increased colony formation in soft agar. Similarly, depletion of ZBRK1, or ectopic overexpression of HMGA2, in MCF10A cells induces abnormal acinar size with increased cell number and inhibits normal acinar formation. Consistently, many BRCA1-deficient mouse breast tumors express higher levels of HMGA2 than BRCA1-proficient tumors. These results suggest that activation of HMGA2 gene expression through derepression of the ZBRK1/BRCA1/CtIP complex is a significant step in accelerating breast tumorigenesis.

Coactivation of ATM/ERK/NF-kappaB in the low-dose radiation-induced radioadaptive response in human skin keratinocytes

Elucidating the molecular mechanism of the low-dose radiation (LDR)-mediated radioadaptive response is crucial for inventing potential therapeutic approaches to improving normal tissue protection in radiation therapy. ATM, a DNA-damage sensor, is known to activate the stress-sensitive transcription factor NF-kappaB upon exposure to ionizing radiation. This study provides evidence of the cooperative functions of ATM, ERK, and NF-kappaB in inducing a survival advantage through a radioadaptive response as a result of LDR treatment (10 cGy X-rays). By using p53-inhibited human skin keratinocytes, we show that phosphorylation of ATM, MEK, and ERK (but not JNK or p38) is enhanced along with a twofold increase in NF-kappaB luciferase activity at 24 h post-LDR. However, NF-kappaB reporter gene transactivation without a significant enhancement of p65 or p50 protein level suggests that NF-kappaB is activated as a rapid protein response via ATM without involving the transcriptional activation of NF-kappaB subunit genes. A direct interaction between ATM and NF-kappaB p65 is detected in the resting cells and this interaction is significantly increased with LDR treatment. Inhibition of ATM with caffeine, KU-55933, or siRNA or inhibition of the MEK/ERK pathway can block the LDR-induced NF-kappaB activation and eliminate the LDR-induced survival advantage. Altogether, these results suggest a p53-independent prosurvival network involving the coactivation of the ATM, MEK/ERK, and NF-kappaB pathways in LDR-treated human skin keratinocytes, which is absent from mutant IkappaB cells (HK18/mIkappaB), which fail to express NF-kappaB activity.

NF-kappaB-mediated HER2 overexpression in radiation-adaptive resistance

The molecular mechanisms governing acquired tumor resistance during radiotherapy remain to be elucidated. In breast cancer patients, overexpression of HER2 (human epidermal growth factor receptor 2) is correlated with aggressive tumor growth and increased recurrence. In the present study, we demonstrate that HER2 expression can be induced by radiation in breast cancer cells with a low basal level of HER2. Furthermore, HER2-postive tumors occur at a much higher frequency in recurrent invasive breast cancer (59%) compared to the primary tumors (41%). Interestingly, NF-kappaB is required for radiation-induced HER2 transactivation. HER2 was found to be co-activated with basal and radiation-induced NF-kappaB activity in radioresistant but not radiosensitive breast cancer cell lines after long-term radiation exposure, indicating that NF-kappaB-mediated HER2 overexpression is involved in radiation-induced repopulation in heterogeneous tumors. Finally, we found that inhibition of HER2 resensitizes the resistant cell lines to radiation. Since HER2 is shown to activate NF-kappaB, our data suggest a loop-like HER2-NF-kappaB-HER2 pathway in radiation-induced adaptive resistance in breast cancer cells.

Comparison of arsenic concentrations in simultaneously-collected groundwater and aquifer particles from Bangladesh, India, Vietnam, and Nepal

One of the reasons the processes resulting in As release to groundwater in southern Asia remain poorly understood is the high degree of spatial variability of physical and chemical properties in shallow aquifers. In an attempt to overcome this difficulty, a simple device that collects groundwater and sediment as a slurry from precisely the same interval was developed in Bangladesh. Recently published results from Bangladesh and India relying on the needle-sampler are augmented here with new data from 37 intervals of grey aquifer material of likely Holocene age in Vietnam and Nepal. A total of 145 samples of filtered groundwater ranging in depth from 3 to 36 m that were analyzed for As (1-1000 mug/L), Fe (0.01-40 mg/L), Mn (0.2-4 mg/L) and S (0.04-14 mg/L) are compared. The P-extractable (0.01-36 mg/kg) and HCl-extractable As (0.04-36 mg/kg) content of the particulate phase was determined in the same suite of samples, in addition to Fe(II)/Fe ratios (0.2-1.0) in the acid-leachable fraction of the particulate phase. Needle-sampler data from Bangladesh indicated a relationship between dissolved As in groundwater and P-extractable As in the particulate phase that was interpreted as an indication of adsorptive equilibrium, under sufficiently reducing conditions, across 3 orders of magnitude in concentrations according to a distribution coefficient of 4 mL/g. The more recent observations from India, Vietnam and Nepal show groundwater As concentrations that are often an order of magnitude lower at a given level of P-extractable As compared to Bangladesh, even if only the subset of particularly reducing intervals characterized by leachable Fe(II)/Fe >0.5 and dissolved Fe >0.2 mg/L are considered. Without attempting to explain why As appears to be particularly mobile in reducing aquifers of Bangladesh compared to the other regions, the consequences of increasing the distribution coefficient for As between the particulate and dissolved phase to 40 mL/g for the flushing of shallow aquifers of their initial As content are explored.

Flushing history as a hydrogeological control on the regional distribution of arsenic in shallow groundwater of the Bengal Basin

Whereas serious health consequences of widespread consumption of groundwater elevated in As have been documented in several South Asian countries, the mechanisms responsible for As mobilization in reducing aquifers remain poorly understood. We document here a previously unrecognized and consistent relationship between dissolved As concentrations in reducing groundwater and the phosphate-mobilizable As content of aquifer sediment for a set of precisely depth-matched samples from across Bangladesh. The relationship holds across nearly 3 orders of magnitude in As concentrations and suggests that regional as well as local patterns of dissolved As in shallow groundwater are set by the solid phase according to a remarkably constant ratio of approximately 250 microg/L dissolved As per 1 mg/kg P-mobilizable As. We use this relationship in a simple model of groundwater recharge to propose that the distribution of groundwater As in shallow aquifers of the Bengal Basin could primarily reflect the different flushing histories of sand formations deposited in the region over the past several thousand years.

ATM-NF-kappaB connection as a target for tumor radiosensitization

Ionizing radiation (IR) plays a key role in both areas of carcinogenesis and anticancer radiotherapy. The ATM (ataxia-telangiectasia mutated) protein, a sensor to IR and other DNA-damaging agents, activates a wide variety of effectors involved in multiple signaling pathways, cell cycle checkpoints, DNA repair and apoptosis. Accumulated evidence also indicates that the transcription factor NF-kappaB (nuclear factor-kappaB) plays a critical role in cellular protection against a variety of genotoxic agents including IR, and inhibition of NF-kappaB leads to radiosensitization in radioresistant cancer cells. NF-kappaB was found to be defective in cells from patients with A-T (ataxia-telangiectasia) who are highly sensitive to DNA damage induced by IR and UV lights. Cells derived from A-T individuals are hypersensitive to killing by IR. Both ATM and NF-kappaB deficiencies result in increased sensitivity to DNA double strand breaks. Therefore, identification of the molecular linkage between the kinase ATM and NF-kappaB signaling in tumor response to therapeutic IR will lead to a better understanding of cellular response to IR, and will promise novel molecular targets for therapy-associated tumor resistance. This review article focuses on recent findings related to the relationship between ATM and NF-kappaB in response to IR. Also, the association of ATM with the NF-kappaB subunit p65 in adaptive radiation response, recently observed in our lab, is also discussed.

NF-kappa B-mediated adaptive resistance to ionizing radiation

Ionizing radiation (IR) began to be a powerful medical modality soon after Wilhelm Röntgen's discovery of X-rays in 1895. Today, more than 50% of cancer patients receive radiotherapy at some time during the course of their disease. Recent technical developments have significantly increased the precision of dose delivery to the target tumor, making radiotherapy more efficient in cancer treatment. However, tumor cells have been shown to acquire a radioresistance that has been linked to increased recurrence and failure in many patients. The exact mechanisms by which tumor cells develop an adaptive resistance to therapeutic fractional irradiation are unknown, although low-dose IR has been well defined for radioadaptive protection of normal cells. This review will address the radioadaptive response, emphasizing recent studies of molecular-level reactions. A prosurvival signaling network initiated by the transcription factor NF-kappa B, DNA-damage sensor ATM, oncoprotein HER-2, cell cyclin elements (cyclin B1), and mitochondrial functions in radioadaptive resistance is discussed. Further elucidation of the key elements in this prosurvival network may generate novel targets for resensitizing the radioresistant tumor cells.

siRNA-mediated MDM2 inhibition sensitizes human lung cancer A549 cells to radiation

MDM2 (murine double minute 2) is well-documented to play a key role in radiation response and tumor radiosensitivity, thus offering an attractive clinic drug target to enhance tumor sensitivity to anti-cancer radiotherapy. In this study, we designed and tested two siRNA fragments against human MDM2 in non-small cell human lung cancer A549 cells. Transfection of mammalian expression vector pUR/U6 containing either MDM2 siRNA1 or siRNA2 fragment was shown to reduce MDM2 mRNA levels by 72% and 31%, respectively. Western blotting detected a similar inhibition of MDM2 protein levels in cells transfected with MDM2 siRNA1. A549 cells transfected with the expression vector for siRNA1 significantly decreased cell proliferation and rendered cells more sensitive to radiation. The basal apoptotic and necrotic cells, 1% and 2%, respectively, detected among A549 cells were increased to 2.6% and 14.4% after gamma-irradiation with 5 Gy. Transfection of MDM2 siRNA1 induced 30.1% apoptosis and 12.7% necrosis while combined treatment of siRNA1 and 5-Gy radiation increased apoptosis and necrosis to 45.9% and 15.2%, respectively. These data provide the first evidence that specific siRNA fragment (MDM2 siRNA1) targeting human MDM2 mRNA is able to enhance lung cancer radiosensitivity.

Therapeutic effects of alpha-lipoic acid on bleomycin-induced pulmonary fibrosis in rats

Pulmonary fibrosis (PF) is a major side effect of radiotherapy and chemotherapy. Recent clinical trials, unfortunately, have failed to identify any therapeutic agent which has the potential to reduce the consequences of this devastating condition. Reactive oxygen species and tissue remodeling regulators, such as metalloproteinases (MMPs) and their inhibitors (TIMPs), are thought to be involved in the development of PF. We investigated these factors to determine the protective effects of antioxidant alpha-lipoic acid (LA) against antineoplastic agent bleomycin (BLM)-induced oxidant lung toxicity in Sprague-Dawley rats. At different time intervals after BLM administration, pathological changes of the lung were analyzed with the measurement of total protein in bronchoalveolar lavage fluid (BALF), hydroxyproline (HYP) content and the level of three oxidative stress markers, i.e. malondialdehyde (MDA), the GSH/GSSG ratio, and total antioxidative capability (T-AOC). Also, the expression changes of MMP-1 and TIMP-1 were measured. At day 14 or 28 after BLM administration, protein content in BALF, and HYP, MDA and T-AOC contents of the lung increased significantly with a decreased GSH/GSSG ratio, implicating an increased efflux of GSSG from the lung and consumption of GSH. In contrast, treatment with LA protected BLM-induced pulmonary injury by suppressing oxidative stress with the reduction of MDA, and the enhancement of the GSH/GSSG ratio and T-AOC. The BLM-stimulated symptoms of PF were relieved with significant reduction of HYP and total proteins in LA-treated rats. LA also ameliorated the MMP-1/TIMP-1 ratio. These results suggest that LA inhibits BLM-induced lung toxicity associated with oxidative damage. Therefore, antioxidant LA has a potential therapeutic effect in the prevention and alleviation of PF.

Nuclear factor-kappaB and manganese superoxide dismutase mediate adaptive radioresistance in low-dose irradiated mouse skin epithelial cells

Mechanisms governing inducible resistance to ionizing radiation in untransformed epithelial cells pre-exposed to low-dose ionizing radiation (LDIR; </=10 cGy) are not well understood. The present study provides evidence that pre-exposure to 10 cGy X-rays increases clonogenic survival of mouse skin JB6P+ epithelial cells subsequently exposed to 2 Gy doses of gamma-rays. To elucidate the molecular pathways of LDIR-induced adaptive radioresistance, the transcription factor nuclear factor-kappaB (NF-kappaB) and a group of NF-kappaB-related proteins [i.e., p65, manganese superoxide dismutase (MnSOD), phosphorylated extracellular signal-regulated kinase, cyclin B1, and 14-3-3zeta] were identified to be activated as early as 15 min after LDIR. Further analysis revealed that a substantial amount of both 14-3-3zeta and cyclin B1 accumulated in the cytoplasm at 4 to 8 h when cell survival was enhanced. The nuclear 14-3-3zeta and cyclin B1 were reduced and increased at 4 and 24 h, respectively, after LDIR. Using YFP-fusion gene expression vectors, interaction between 14-3-3zeta and cyclin B1 was visualized in living cells, and LDIR enhanced the nuclear translocation of the 14-3-3zeta/cyclin B1 complex. Treatment of JB6P+ cells with the NF-kappaB inhibitor IMD-0354 suppressed LDIR-induced expression of MnSOD, 14-3-3zeta, and cyclin B1 and diminished the adaptive radioresistance. In addition, treatment with small interfering RNA against mouse MnSOD was shown to inhibit the development of LDIR-induced radioresistance. Together, these results show that NF-kappaB, MnSOD, 14-3-3zeta, and cyclin B1 contribute to LDIR-induced adaptive radioresistance in mouse skin epithelial cells.

Targeting low-arsenic groundwater with mobile-phone technology in Araihazar, Bangladesh

The Bangladesh Arsenic Mitigation and Water Supply Program (BAMWSP) has compiled field-kit measurements of the arsenic content of groundwater for nearly five million wells. By comparing the spatial distribution of arsenic inferred from these field-kit measurements with geo-referenced laboratory data in a portion of Araihazar upazila, it is shown here that the BAMWSP data could be used for targeting safe aquifers for the installation of community wells in many villages of Bangladesh. Recent experiences with mobile-phone technology to access and update the BAMWSP data in the field are also described. It is shown that the technology, without guaranteeing success, could optimize interventions by guiding the choice of the drilling method that is likely to reach a safe aquifer and identifying those villages where exploratory drilling is needed.

Impact of irrigating rice paddies with groundwater containing arsenic in Bangladesh

Soil and soil-water As profiles were obtained from 4 rice paddies in Bangladesh during the wet growing season (May-November), when surface water with little arsenic is used for irrigation, or during the dry season (January-May), when groundwater elevated in arsenic is used instead. In the upper 5 cm of paddy soil, accumulation of 13+/-12 mg/kg acid-leachable As (n=11) was observed in soil from 3 sites irrigated with groundwater containing 80-180 microg/L As, whereas only 3+/-2 mg/kg acid-leachable As (n=8) was measured at a control site. Dissolved As concentrations averaged 370+/-340 microg/L (n=7) in the upper 5 cm of the soil at the 3 sites irrigated with groundwater containing 80-180 microg/L As, contrasting with soil water As concentrations of only 18+/-7 microg/L (n=4) over the same depth interval at the control site. Despite the accumulation of As in soil and in soil water attributable to irrigation with groundwater containing elevated As levels, there is no evidence of a proportional transfer to rice grains collected from the same sites. Digestion and analysis of individual grains of boro winter rice from the 2 sites irrigated with groundwater containing 150 and 180 microg/L As yielded concentrations of 0.28+/-0.13 mg/kg (n=12) and 0.44+/-0.25 mg/kg (n=12), respectively. The As content of winter rice from the control site was not significantly different though less variable (0.30+/-0.07; n=12). The observations suggest that exposure of the Bangladesh population to As contained in rice is less of an immediate concern than the continued use of groundwater containing elevated As levels for drinking or cooking, or other potential consequences of As accumulation in soil and soil-water.

Responses of 6500 households to arsenic mitigation in Araihazar, Bangladesh

This study documents the response of 6500 rural households in a 25 km(2) area of Bangladesh to interventions intended to reduce their exposure to arsenic contained in well water. The interventions included public education, posting test results for arsenic on the wells, and installing 50 community wells. Sixty-five percent of respondents from the subset of 3410 unsafe wells changed their source of drinking water, often to new and untested wells. Only 15% of respondents from the subset of safe wells changed their source, indicating that health concerns motivated the changes. The geo-referenced data indicate that distance to the nearest safe well also influenced household responses.

Limited temporal variability of arsenic concentrations in 20 wells monitored for 3 years in Araihazar, Bangladesh

Millions of people in Bangladesh have probably switched their water consumption to wells that meet the local standard for As in drinking water of 50 microg/L as a result of blanket field testing throughout the country. It is therefore important to know if As concentrations in those wells could change over time. To address this issue, we report here precise groundwater As analyses for time-series samples collected from a suite of 20 tube wells containing < or =50 microg/L As and ranging from 8 to 142 m in depth. For 17 out of 20 wells, the standard deviation of groundwater As concentrations was <10 microg/L over the 3-year monitoring period (n = 24-44 per well). Six of the 17 wells are community wells, each of which serves the needs of several hundred people in particularly affected villages. Of the three wells showing larger fluctuations in chemical composition including As, two are very shallow (8 and 10 m). Variations in As concentrations for one of these wells (50 +/- 32 microg/L, n = 36), as well as another shallow well showing smaller variations (48 +/- 5 microg/L, n = 36), appear to be coupled to seasonal precipitation and recharge linked to the monsoon. The other shallow well showing larger variations in composition indicates a worrisome and steady increase in As concentrations from 50 to 70 microg/L (n = 36) over 3 years. The time series of As (30 +/- 11 microg/L, n = 24) and other constituents in one deep community well (59 m) show large fluctuations that suggest entrainment of shallow groundwater through a broken PVC pipe. Even though the majority of wells that were initially safe remained so for 3 years, our results indicate that tube wells should be tested periodically.

Reliability of a commercial kit to test groundwater for arsenic in Bangladesh

A comparison of field and laboratory measurements of arsenic in groundwater of Araihazar, Bangladesh, indicates that the most widely used field kit correctly determined the status of 88% of 799 wells relative to the local standard of 50 microg/L As. Additional tests showthatthe inconsistencies, mainly underestimates in the 50-100 microg/L As range, can be avoided by increasing the reaction time from 20 to 40 min. Despite this limitation, the field data already compiled for millions of wells by the Bangladesh Arsenic Mitigation and Water Supply Project, in combination with information on well location and depth, should prove to be extremely useful to prioritize interventions in thousands of affected villages.

Testing groundwater for arsenic in Bangladesh before installing a well

Profiles of groundwater and sediment properties were collected at three sites in Bangladesh with an inexpensive sampling device that is deployed by modifying the local manual drilling method. Dissolved As concentrations in the groundwater samples ranging from 5 to 600 microg/L between 5 and 50 m depth closely matched vertical profiles from nearby nests of monitoring wells. In combination with a field kit, the device provides a means of targeting aquifers for the installation of tube wells that meet the drinking water standard for As. The device is also a useful research tool for unraveling the relationships between the As content of groundwater and the complex structure of flood plain and deltaic environments throughout South Asia.

Community wells to mitigate the arsenic crisis in Bangladesh

OBJECTIVE

To monitor the effectiveness of deep community wells in reducing exposure to elevated levels of arsenic in groundwater pumped from shallower aquifers.

METHODS

Six community wells ranging in depth from 60 m to 140 m were installed in villages where very few of the wells already present produced safe water. By means of flow meters and interviews with villagers carrying water from the community wells, a study was made of the extent to which these were used during one year. The results were compared with household and well data obtained during a previous survey in the same area.

FINDINGS

The mean arsenic concentration in water pumped from wells already in use in the villages where the community wells, were installed was 180 +/- 140 micrograms/l (n = 956). Monthly sampling for 4-11 months showed that arsenic levels in groundwater from five of the six newly installed wells were consistently within the WHO guideline value of 10 micrograms/l for drinking-water. One of these wells met the Bangladesh standard of 50 micrograms/l arsenic but failed to meet the WHO guideline values for manganese and uranium in drinking-water. The community wells were very popular. Many women walked hundreds of metres each day to fetch water from them. On average, 2200 litres were hand-pumped daily from each community well, regardless of the season.

CONCLUSION

A single community well can meet the needs of some 500 people residing within a radius of 150 m of it in a densely populated village. Properly monitored community wells should become more prominent in campaigns to reduce arsenic exposure in Bangladesh. Between 8000 and 10,000 deep community wells are needed to provide safe water for the four to five million people living in the most severely affected parts of the country.

Association of an intronic polymorphism in the midkine (MK) gene with human sporadic colorectal cancer

Midkine (MK) is a heparin-binding growth factor specified by a retinoic acid responsive gene. It plays important roles in development and carcinogenesis. The MK gene is located on chromosome 11q11.2 in humans. A heterozygous G to T transition at the 62nd base in intron 3 of this gene has been identified in sporadic colorectal and gastric cancers (Int. J. Mol. Med. 6 (2000) 281). To clarify whether this polymorphism is associated with a cancer risk, a case-control study was conducted. We examined 98 colorectal, 60 gastric, 59 esophagus, 32 lung and 37 breast cancer tissue specimens and their corresponding non-neoplastic tissues. Also, 86 unaffected control specimens were examined. The G/T genotype frequency in colorectal cancers was higher than that in normal samples (11.2 versus 2.3%; P=0.017). Therefore, this genotype could represent a risk factor for tumorigenesis in the colon and rectum of Japanese.

Effect of combined praziquantel and recombinant glutathione S-transferase on resistance to reinfection in murine Schistosomiasis mansoni

This study was undertaken to evaluate the effect of recombinant Schistosoma mansoni-26 Glutathione S-transferase (rSm 26 GST) or soluble egg antigen (SEA) alone and in addition to praziquantel (PZQ) on the state of resistance to S. mansoni reinfection. The associated changes in the immune responses were evaluated. The experimental group of mice were injected intravenously before S. mansoni infection (80 cercariae/mouse) either with rSm26 GST (1 microgx4) or SEA (10 microgx4) in addition to PZQ (2x500 mg/kg) administered 6 weeks post-infection. Seven control groups were used, three of them were the infected (80 cercariae/mouse), the challenged (240 cercariae/mouse) and the infected challenged controls (80+240 cercariae/mouse). The rest of the four groups were the treated controls receiving: the GST-Lyzate, rSmGST, SEA and PZQ in the same doses and at the same timings. Challenge infection was conducted for all the groups 8 weeks post-infection. Animals were sacrificed 3 weeks post-challenge. After sacrifice animals were perfused and percentage resistance to reinfection was calculated. Immune responses were assessed by the measurement of hepatic granuloma diameter, intralesional T-cell phenotypes and serum immunoglobulin isotypes. The highest percentage of resistance to reinfection was observed in rGST-treated group while the lowest percentage of resistance was detected in PZQ-treated group. Whereas in mice receiving combined rGST or SEA and PZQ, percentage resistance to reinfection was significantly higher than that in PZQ treated mice. The remarkable reduction in granuloma diameter in rGST-treated group with or without PZQ was associated with decrease in the intralesional L(3)T(4)(+) and increase in Lyt(2)(+) T-cell phenotypes. However, no special relationship was observed between the percentage of resistance and the changes in granuloma diameter or intralesional T-cell phenotypes. The increase in percentage resistance to reinfection was found accompanied by increased anti SWAP IgE. Combined rGST and PZQ provided the complementary goals of improved state of resistance to reinfection 'which was compromized after cure with PZQ' and the maximal reduction in granuloma diameter.

Genetic variations of the midkine (MK) gene in human sporadic colorectal and gastric cancers

Midkine (MK), a retinoic acid responsible protein, is regulated during development and may play an important role in tumorigenesis. A search for genetic variations of the MK gene, located on chromosome 11q11.2 in humans, has not yet been conducted in cancers. To examine the entire coding region, as well as 4 regions of the promoter covering all functional motifs, 8 sets of intron-based and promoter region primers were designed. Using these primers, polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis of genomic DNA samples from 60 sporadic colorectal and 37 sporadic gastric cancer patients was carried out. This analysis, followed by DNA sequencing, revealed a heterozygous g/t polymorphism at the 62nd base on intron 3 in five colorectal tumors (8.3%) and one gastric tumor (2.7%). In the promoter region, a heterozygous CTT deletion, creating a (CTTTT)2 repeat, in one colorectal cancer sample (1.67%) and a heterozygous 2-bp deletion in the G7 tract in another colorectal cancer patient were detected. A/G and A/A alleles were also detected at nt. -1741 in 36 (97.3%) and one (2.7%) gastric cancer samples, respectively. The A/G alleles were observed in all colorectal cancer patients (100%). All variations observed in the promoter region showed polymorphism. These results suggest that in sporadic colorectal and gastric cancers some gene alterations are present in the MK promoter region, but alterations in the coding region are rare.

A new flavone diglycoside from Carthamus tinctorius seeds

From the aqueous ethanol extract (AE) of Carthamus tinctorius seeds, a new acacetin diglycoside has been isolated and identified as acacetin 7-O-beta-D-apiofuranosyl-(1"'-->6" instead of 6')-O-beta-D-glucopyranoside together with previously isolated kaempferol 7-O-beta-D-glucopyranoside, acacetin 7-O-alpha-L-rhamnopyranoside and acacetin. The structures of these metabolites have been established on the basis of chemical, chromatographic and spectral methods.

A new flavonoid from Limonium axillare

A new flavonol glycoside identified as myricetin 3-O-beta-D-sorboside (1) has been isolated from the leaves of L. axillare. The new compound showed a moderate inhibition of Ehrlich ascites carcinoma cells.

Molecular analysis of toxigenic Vibrio cholerae O139 Bengal strains isolated in Bangladesh between 1993 and 1996: evidence for emergence of a new clone of the Bengal vibrios

Vibrio cholerae O139 Bengal emerged in 1992 and rapidly spread in an epidemic form, in which it replaced existing strains of V. cholerae O1 in Bangladesh during 1992 and 1993. The subsequent emergence of a new clone of V. cholerae O1 of the El Tor biotype that transiently displaced the O139 vibrios during 1994 to 1995 and the recent reemergence of V. cholerae O139 and its coexistence with the El Tor vibrios demonstrated temporal changes in the epidemiology of cholera in Bangladesh. We studied clonal diversity among V. cholerae O139 strains isolated from cholera patients and environmental surface water since their first appearance until their transient disappearance in 1994 as well as the O139 strains that reemerged during 1995 to 1996 and were isolated in the capital Dhaka and four rural districts of Bangladesh to investigate the origin of the reemerged strains. Analysis of restriction fragment length polymorphisms in genes for conserved rRNA and cholera toxin (CT) (ctxA) or in DNA sequences flanking these genes revealed four different ribotypes and four different ctx genotypes among the 93 strains of V. cholerae O139 studied. Ribotypes I and II and ctx genotypes A through C were shared by strains isolated from the epidemic outbreak during 1992 and 1993 in Bangladesh and India, ribotype III was represented by a single CT-negative O139 strain from Argentina, and 16 of 27 (59.2%) of the reemerged strains isolated during 1995 and 1996 belonged to a new ribotype of O139 vibrios designated ribotype IV. All 16 strains belonging to ribotype IV also belonged to a new ctx genotype (genotype 4). These results provide evidence for the emergence of a new clone of toxigenic V. cholerae O139 in Bangladesh. Further analysis of the rfb gene cluster by PCR revealed the absence of a large region of the O1-specific rfb operon and the presence of an O139-specific genomic region in all O139 strains. The PCR amplicon corresponding to the rfaD gene of a CT-negative O139 strain from Argentina was smaller in length than those of the toxigenic O139 strains but was identical to those of seven non-O1 and non-O139 strains. All O139 strains except the CT-negative strain carried structural and regulatory genes for CT and toxin-coregulated pili (ctxA, tcpA, tcpI, and toxR). These results suggest that the O139 Bengal strains possibly emerged from an El Tor strain but that the CT-negative non-Bengal O139 strain might have emerged from a non-O1, non-O139 strain. Thus, strains belonging to the O139 serogroup may have emerged from similar serotype-specific genetic changes in more than one progenitor strain of V. cholerae.

Emergence of a new clone of toxigenic Vibrio cholerae O1 biotype El Tor displacing V. cholerae O139 Bengal in Bangladesh

The emergence of Vibrio cholerae O139 Bengal in 1993, its rapid spread in an epidemic form, in which it replaced existing strains of V. cholerae O1 during 1992 and 1993, and the subsequent reemergence of V. cholerae O1 of the El Tor biotype in Bangladesh since 1994 have raised questions regarding the origin of the reemerged El Tor vibrios. We studied 50 El Tor vibrio strains isolated in Bangladesh and four other countries in Asia and Africa before the emergence of V. cholerae O139 and 32 strains isolated in Bangladesh during and after the epidemic caused by V. cholerae O139 and 32 strains isolated in Bangladesh during and after the epidemic caused by V. cholerae O139 to determine whether the reemerged El Tor vibrios were genetically different from the El Tor vibrios which existed before the emergence of V. cholerae O139. Analysis of restriction fragment length polymorphisms in genes for conserved rRNA, cholera toxin (ctxA), and zonula occludens toxin (zot) or in DNA sequences flanking the genes showed that the El Tor strains isolated before the emergence of V. cholerae O139 belonged to four different ribotypes and four different ctx genotypes. Of 32 El Tor strains isolated after the emergence of O139 vibrios, 30 strains (93.7%) including all the clinical isolates belonged to a single new ribotype and a distinctly different ctx genotype. These results provide evidence that the reemerged El Tor strains represent a new clone of El Tor vibrios distinctly different from the earlier clones of El Tor vibrios which were replaced by the O139 vibrios. Further analysis showed that all the strains carried the structural and regulatory genes for toxin-coregulated pilus (tcpA, tcpI, and toxR). All strains of the new clone produced cholera toxin (CT) in vitro, as assayed by the GM1-dependent enzyme-linked immunosorbent assay, and the level of CT production was comparable to that of previous epidemic isolates of El Tor vibrios. Further studies are required to assess the epidemic potential of the newly emerged clone of V. cholerae O1 and to understand the mechanism of emergence of new clones of toxigenic V. cholerae.

The role of village leaders in the implementation of multidrug therapy for leprosy, Sudan -- a pilot study in the Angasana Hills

The purpose of this study is to implement multidrug therapy (MDT) and to evaluate the possible role of village leaders in supervising MDT treatment in remote and inaccessible areas in Sudan where health facilities are poor. Three villages from the Angasana Hills in the south-east of Sudan, where leprosy is endemic, have been chosen for this study. A health education course for village leaders in the area was conducted. Three medical assistants from a nearby village were identified to examine all leprosy suspects and to put the diagnosed cases on treatment. The village leaders were to supervise the treatment of the patients during the rainy season. Out of 43 cases detected all paucibacillary (PB) cases detected (11 cases) completed their treatment and 28 out of 32 multibacillary (MB) cases were regularly on treatment. It has been obvious that the village leaders were useful in supervising MDT in the Angasana area, a process which can be extended to other inaccessible areas in the Sudan.

Community based distribution of ivermectin in eastern Sudan: acceptability and early post-treatment reactions

A study to monitor ivermectin acceptability and post-treatment reactions during mass community distribution was carried out in eastern Sudan, where severe reactive onchodermatitis is prevalent. Of 1081 individuals eligible for treatment, 1076 (99.5%) accepted the ivermectin. Post-treatment reactions were monitored by self reporting, 5 d after a single dose of about 150 micrograms/kg (range 103-200 micrograms/kg); 230 persons reported adverse events (21.4%). No reaction was rated as severe. The most common problem was itching with cutaneous papular eruptions (16.2%). Local oedematous swelling was the second most common and the most slowly resolving complaint (5.4%), followed by musculoskeletal pain. There was a high acceptance rate of the treatment and remarkable tolerance of the post-treatment effects, probably due to efforts made to prepare the community to expect reactions to ivermectin, widespread awareness of the beneficial effects of treatment by villagers who had participated in clinical trials previously, and the encouragement we gave to the population to become involved in improvement of their health care services. Single doses of ivermectin resulted in good clinical responses and created much goodwill among villagers. Improvements in physical fitness, ability to work, and freedom from musculoskeletal pain were reported at the 3 months' follow-up. We recommend that, during mass distribution of ivermectin, community involvement in planning overall health improvement should be included, since the treatment initiates the process well. In areas where sowda syndrome is prevalent, medical surveillance for 3 d or more should be considered.

An evaluation of nitinol and stainless steel files used by dental students during a laboratory proficiency exam

Eighty-one dental students instrumented two curved canals in acrylic blocks with the use of stainless steel files in one block and nitinol files in the other. Overlay tracings were made of photographs taken before and after instrumentation of the acrylic blocks and differences between the tracings were measured along the canal walls. The canals instrumented with nitinol files were shaped better than those instrumented with stainless steel files; working length was maintained more often without ledging the canal walls and with less zipping of the apical foramen.

Tissue glutathione levels in mice treated with delta-9-tetrahydrocannabinol

Glutathione (GSH) is widely distributed among living cells and is involved in many biological functions. It provides the sulfhydryl groups for conjugation of toxic metabolites of several xenobiotica. Acetaminophen (Tylenol) toxicity is a classical example of this property. For this purpose, we studied the effects of delta-9-tetrahydrocannabinol (THC) on tissue levels of GSH in the mice. Groups of male Swiss Webster mice weighing 25 +/- 5 g were treated with 50 mg/kg, PO THC at 1300 h. Control mice were given equal volume of sesame oil (5 ml/kg, PO) which was the vehicle for THC. Ninety minutes following THC administration, mice were sacrificed, their plasma, brain, heart, liver, kidney and testis were collected. All tissues were homogenized in 5% TCA/EDTA solution and supernatant solutions of these homogenates were diluted. In these diluted samples, levels of GSH were determined by a modified spectrophotometric procedure and the GSH levels were expressed as micromoles of GSH/g tissue. In this study, THC caused no effects on GSH levels in brain, heart, testis and plasma. However, GSH levels in liver and kidney were decreased by 14% and 7% respectively. Although the decrease in kidney GSH levels were insignificant, these changes in liver and kidney could be indicative of a possible metabolic and/or dispositional interaction between THC and different commonly available drugs such as acetaminophen.