Lead Isotope Signatures and Source Identification of Heavy Metals in Vegetable Soils Irrigated with Swine Wastewater of Jiangxi Province, China.

The rapid development of livestock and poultry industry in China has caused serious environment pollution problems. To understand the heavy metals accumulation and identify their sources, 7 heavy metals contents and lead isotope ratios were determined in 24 soil samples from vegetable fields irrigated with swine wastewater in Dongxiang County, Jiangxi Province, China. The results showed that the concentration of Cr, Ni, Cu, Zn, As, Cd and Pb in the swine wastewater irrigated vegetable soils varied from 38.5 to 86.4, 7.57 to 30.6, 20.0 to 57.1, 37.5 to 174, 9.18 to 53.1, 0.043 to 0.274 and 12.8 to 37.1 mg/kg, respectively. The soils were moderately to heavily polluted by As, moderately polluted by Cr, Ni, Cu, Zn and Cd, and unpolluted to moderately polluted by Pb. Sampling soils were classified as moderately polluted according to the Nemerow comprehensive pollution index. Lead isotope and Principal Component Analysis (PCA) analysis indicated that swine wastewater irrigation and atmospheric deposition were the primary sources of the heavy metals.

Constructing CoNi-LDH/Fe MOF/NF Heterostructure Catalyst for Energy-Efficient OER and UOR at High Current Density.

The sluggish kinetics of the oxygen evolution reaction (OER) always results in a high overpotential at the anode of water electrolysis and an excessive electric energy consumption, which has been a major obstacle for hydrogen production through water electrolysis. In this study, we present a CoNi-LDH/Fe MOF/NF heterostructure catalyst with nanoneedle array morphology for the OER. In 1.0 M KOH solution, the heterostructure catalyst only required overpotentials of 275 and 305 mV to achieve high current densities of 500 and 1000 mA/cm2 for OER, respectively. The catalytic activities are much higher than those of the reference single-component CoNi-LDH/NF and Fe MOF/NF catalysts. The improved catalytic performance of the heterostructure catalyst can be ascribed to the synergistic effect of CoNi-LDH and Fe MOF. In particular, when the anodic OER is replaced with the urea oxidation reaction (UOR), which has a relatively lower thermodynamic equilibrium potential and is expected to reduce the cell voltage, the overpotentials required to achieve the same current densities can be reduced by 80 and 40 mV, respectively. The cell voltage required to drive overall urea splitting (OUS) is only 1.55 V at 100 mA/cm2 in the Pt/C/NF||CoNi-LDH/Fe MOF/NF two-electrode electrolytic cell. This value is 60 mV lower compared with that required for overall water splitting (OWS). Our results indicate that a reasonable construction of a heterostructure catalyst can significantly give rise to higher electrocatalytic performance, and using UOR to replace the anodic OER of the OWS can greatly reduce the electrolytic energy consumption.

Research progress on mechanisms of acupuncture and moxibustion underlying improvement of oxidative stress. / é’ˆç¸æ”¹å–„æ°§åŒ–åº”æ¿€ä½œç”¨æœºåˆ¶çš„ç ”ç©¶è¿›å±•.

Oxidative stress is associated with a variety of disease pathologies, it may lead to mitochondrial dysfunction, damage of impaired DNA repairment, cell damage or apoptosis. Acupuncture and moxibustion therapy has been proved to have a role in reducing oxidative stress in organisms under pathological conditions. In the present paper, we collected literatures in both English and Chinese from domestic and foreign databases on the mechanisms of acupuncture and moxibustion underlying amelioration of oxidative stress over the past 5 years, and analyzed the link between acupuncture-moxibustion intervention and redox biology from four aspects： 1) regulation of the production of reactive oxygen species (ROS), 2) affecting antioxidant enzyme-related pathways to reduce ROS, 3) repairing proteins, lipids and DNAs attacked by ROS, and 4) inhibiting downstream apoptosis or autophagy of ROS pathway. By summarizing and prospecting such antioxidant mechanisms, this paper may provide some basis and ideas for in-depth mechanism research on acupuncture and moxibustion to improve oxidative stress and related diseases.

Resolving defence mechanisms: A perspective based on dissipative structure theory.

Theories and classifications of defence mechanisms are not unified. This study addresses the psychological system as a dissipative structure which exchanges information with the external and internal world. When using defence mechanisms, the cognitive-affective schema of an individual could remain stable and ordered by excluding psychological entropy, obtaining psychological negentropy or by dissipating the energy of self-presentation. From this perspective, defences can be classified into three basic types: isolation, compensation and self-dissipation. However, not every kind of defence mechanisms can actually help the individual. Non-adaptive defences are just functioning as an effective strategy in the short run but can be a harmful approach in the long run, while adaptive defences could instead help the individual as a long-term mechanism. Thus, we would like to suggest that it is more useful for the individual to use more adaptive defence mechanisms and seek out social or interpersonal support when undergoing psychic difficulties. As this model of defences is theoretical at present, we therefore aim to support and enrich this viewpoint with empirical evidence.

Neural mass models as a tool to investigate neural dynamics during seizures.

Epilepsy is one of the most common neurological disorders and is characterized by recurrent seizures. We use theoretical neuroscience tools to study brain dynamics during seizures. We derive and simulate a computational model of a network of hippocampal neuronal populations. Each population within the network is based on a model that has been shown to replicate the electrophysiological dynamics observed during seizures. The results provide insights into possible mechanisms for seizure spread. We observe that epileptiform activity remains localized to a pathological region when a global connectivity parameter is less than a critical value. After establishing the critical value for seizure spread, we explored how to correct the effect by altering particular synaptic gains. The spreading of seizures is quantified using numerical methods for seizure detection. The results from this study provide a new avenue of exploration for seizure control.

Jackknife variance of the partial area under the empirical receiver operating characteristic curve.

Receiver operating characteristic analysis provides an important methodology for assessing traditional (e.g., imaging technologies and clinical practices) and new (e.g., genomic studies, biomarker development) diagnostic problems. The area under the clinically/practically relevant part of the receiver operating characteristic curve (partial area or partial area under the receiver operating characteristic curve) is an important performance index summarizing diagnostic accuracy at multiple operating points (decision thresholds) that are relevant to actual clinical practice. A robust estimate of the partial area under the receiver operating characteristic curve is provided by the area under the corresponding part of the empirical receiver operating characteristic curve. We derive a closed-form expression for the jackknife variance of the partial area under the empirical receiver operating characteristic curve. Using the derived analytical expression, we investigate the differences between the jackknife variance and a conventional variance estimator. The relative properties in finite samples are demonstrated in a simulation study. The developed formula enables an easy way to estimate the variance of the empirical partial area under the receiver operating characteristic curve, thereby substantially reducing the computation burden, and provides important insight into the structure of the variability. We demonstrate that when compared with the conventional approach, the jackknife variance has substantially smaller bias, and leads to a more appropriate type I error rate of the Wald-type test. The use of the jackknife variance is illustrated in the analysis of a data set from a diagnostic imaging study.

Estimating the Area Under ROC Curve When the Fitted Binormal Curves Demonstrate Improper Shape.

RATIONALE AND OBJECTIVES: The "binormal" model is the most frequently used tool for parametric receiver operating characteristic (ROC) analysis. The binormal ROC curves can have "improper" (non-concave) shapes that are unrealistic in many practical applications, and several tools (eg, PROPROC) have been developed to address this problem. However, due to the general robustness of binormal ROCs, the improperness of the fitted curves might carry little consequence for inferences about global summary indices, such as the area under the ROC curve (AUC). In this work, we investigate the effect of severe improperness of fitted binormal ROC curves on the reliability of AUC estimates when the data arise from an actually proper curve. MATERIALS AND METHODS: We designed theoretically proper ROC scenarios that induce severely improper shape of fitted binormal curves in the presence of well-distributed empirical ROC points. The binormal curves were fitted using maximum likelihood approach. Using simulations, we estimated the frequency of severely improper fitted curves, bias of the estimated AUC, and coverage of 95% confidence intervals (CIs). In Appendix S1, we provide additional information on percentiles of the distribution of AUC estimates and bias when estimating partial AUCs. We also compared the results to a reference standard provided by empirical estimates obtained from continuous data. RESULTS: We observed up to 96% of severely improper curves depending on the scenario in question. The bias in the binormal AUC estimates was very small and the coverage of the CIs was close to nominal, whereas the estimates of partial AUC were biased upward in the high specificity range and downward in the low specificity range. Compared to a non-parametric approach, the binormal model led to slightly more variable AUC estimates, but at the same time to CIs with more appropriate coverage. CONCLUSIONS: The improper shape of the fitted binormal curve, by itself, ie, in the presence of a sufficient number of well-distributed points, does not imply unreliable AUC-based inferences.

Development of a Method for the Analysis of Multiclass Antibiotic Residues in Milk Using QuEChERS and Liquid Chromatography-Tandem Mass Spectrometry.

A precise and simplified method of sample preparation for the simultaneous quantification of the antibiotics ß-lactam, macrolide, tetracycline, sulfonamide, and quinolone in bovine milk was developed. The central composite design of response surface methodology was used to design and optimize the method for the determination of six different antibiotic residues in milk. The recovery of each antibiotic was studied using a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method. Octadecylsilane (C18), primary secondary amine (PSA), and sodium acetate (Na acetate) were the main factors affecting the recovery of each antibiotic. After optimization, the maximum predicted recovery rate was 84.18% for erythromycin under the optimized conditions of 101.20 mg C18, 52.00 mg PSA, and 1.01 g Na acetate. The recovery rates of the five other antibiotic residues ranged from 86.09% to 115.99%. The results suggested that modified QuEChERS could effectively be implemented in the analysis of antibiotic residues in milk.

A new comprehensive index for discriminating adulteration in bovine raw milk.

This paper proposes a new comprehensive index, called Q, which can effectively discriminate artificial adulterated milk from unadulterated milk. Both normal and adulterated samples of bovine raw milk were analysed by Fourier transform infrared spectroscopic instrument to measure the traditional indices of quality, including fat (FAT), protein (PRO), lactose (LAC), total solids (TS), non-fat solid (NFS), freezing point (FP) and somatic cell counts (SCC). From these traditional indices, this paper elaborates a method to build the index Q. First, correlated analysis and principle component analysis were used to select parameter pairs TS-FAT and FP-LAC as predominant variables. Second, linear-regression analysis and residual analysis are applied to determine the index Q and its discriminating ranges. The verification and two-blind trial results suggested that index Q could accurately detect milk adulteration with maltodextrin and water (as low as 1.0% of adulteration proportions), and with other nine kinds of synthetic adulterants (as low as 0.5% of adulteration proportions).

Comparison of two-dimensional synthesized mammograms versus original digital mammograms alone and in combination with tomosynthesis images.

PURPOSE: To assess interpretation performance and radiation dose when two-dimensional synthesized mammography (SM) images versus standard full-field digital mammography (FFDM) images are used alone or in combination with digital breast tomosynthesis images. MATERIALS AND METHODS: A fully crossed, mode-balanced multicase (n = 123), multireader (n = 8), retrospective observer performance study was performed by using deidentified images acquired between 2008 and 2011 with institutional review board approved, HIPAA-compliant protocols, during which each patient signed informed consent. The cohort included 36 cases of biopsy-proven cancer, 35 cases of biopsy-proven benign lesions, and 52 normal or benign cases (Breast Imaging Reporting and Data System [BI-RADS] score of 1 or 2) with negative 1-year follow-up results. Accuracy of sequentially reported probability of malignancy ratings and seven-category forced BI-RADS ratings was evaluated by using areas under the receiver operating characteristic curve (AUCs) in the random-reader analysis. RESULTS: Probability of malignancy-based mean AUCs for SM and FFDM images alone was 0.894 and 0.889, respectively (difference, -0.005; 95% confidence interval [CI]: -0.062, 0.054; P = .85). Mean AUC for SM with tomosynthesis and FFDM with tomosynthesis was 0.916 and 0.939, respectively (difference, 0.023; 95% CI: -0.011, 0.057; P = .19). In terms of the reader-specific AUCs, five readers performed better with SM alone versus FFDM alone, and all eight readers performed better with combined FFDM and tomosynthesis (absolute differences from 0.003 to 0.052). Similar results were obtained by using a nonparametric analysis of forced BI-RADS ratings. CONCLUSION: SM alone or in combination with tomosynthesis is comparable in performance to FFDM alone or in combination with tomosynthesis and may eliminate the need for FFDM as part of a routine clinical study.

Facile synthesis and excellent recyclable photocatalytic activity of pine cone-like Fe3O4@Cu2O/Cu porous nanocomposites.

L-Cys-modified Fe3O4 was first prepared by a one-step partially-reduced method under mild conditions. Then, novel pine cone-like Fe3O4@Cu2O/Cu nanocomposites (NCs) with photomagnetic difunction were successfully synthesized via a one-pot solvothermal method on Fe3O4 without any additional linker or reducer. The average diameter of the as-synthesized products was about 4 µm, and the products were orderly assembled into many sheets with an average thickness of ~100 nm, possessing a porous structure. A possible formation mechanism of Fe3O4@Cu2O/Cu NCs involving interfacial recognization of ions, nucleation, aggregation, in situ transformation from Cu2O to Cu and Ostwald ripening process is proposed. The pine cone-like porous composites show excellent photocatalytic activity such that MO degradation efficiency is about 96% at an irradiation time of 20 min under visible light. Also, the composites present higher stability than Fe3O4@Cu2O and do not exhibit any significant loss after five recycles for the photodegradation of MO. The above results demonstrate that Cu could improve the photocatalytic activity of NCs and also inhibit the photocorrosion behavior of NCs. These novel Fe3O4@Cu2O/Cu composite materials are ideal candidates in water treatment and environmental cleaning as well as in magnetic applications, etc.

[Reverse osmosis membrane fouling by humic acid using XDLVO approach: effect of calcium ions].

Interfacial interactions involved in reverse osmosis (RO) membrane fouling by humic acid were quantitatively evaluated using the XDLVO (extended Derjaguin-Landau-Verwey-Overbeek) approach. The role of each individual interfacial interaction during membrane fouling was elucidated with special emphasis devoted into the influence of Ca2+ under different solution pHs. The results showed that, regardless of the presence of Ca2+, van der Waals interaction favoring fouling contributed the most to the interfacial interactions at pH 3, whereas the polar interaction inhibiting fouling played a dominant role at pH 7 and pH 10. Electrostatic double layer interaction appeared to be the weakest in all cases, thus contributing the least to membrane fouling. It was the changing of polar interaction that gave rise to the influence of Ca2+ on membrane fouling, which turned out to be more significant at lower pH. Ca2+ would accelerate humic acid RO membrane fouling at most cases. Correlation analysis between interfacial free energy and fouling extent revealed that XDLVO approach could reasonably predict humic acid RO membrane fouling behaviors under different solution conditions.

Expression of intercellular adhesion molecule (ICAM)-1 or ICAM-2 is critical in determining sensitivity of pancreatic cancer cells to cytolysis by human gammadelta-T cells: implications in the design of gammadelta-T-cell-based immunotherapies for pancreatic cancer.

BACKGROUND AND AIMS: gammadelta-T cells can recognize and kill malignant cells, particularly those of epithelial origin, through mechanisms which do not require the recognition of tumor-specific antigens (innate immune response). This natural ability of gammadelta-T cells to kill tumor cells in a tumor antigen-independent manner provides a strong rationale for developing clinical trials designed to exploit the innate antitumor properties of gammadelta-T cells. METHODS: In vitro studies were carried out to asses the sensitivity of pancreatic cancer cells (MIA PaCa2, BxPC-3, PANC-1) to killing by ex vivo expanded human gammadelta-T cells. RESULTS: The capacity of gammadelta-T cells to bind to as well as to kill pancreatic cancer cells correlated with the degree of surface expression of key intercellular adhesion molecules (ICAM) present on pancreatic cancer cells. Moreover, pancreatic cancer cells expressing neither ICAM-1 nor ICAM-2 were bound poorly by gammadelta-T cells and were found to be resistant to gammadelta-T-cell killing. However, upon transfection of resistant cells with ICAM-1 or ICAM-2, gammadelta-T cells were then able to bind to and subsequently kill these cells. CONCLUSION: In vitro, the expression of ICAM-1 or ICAM-2 on human pancreatic cancer cells is critically important in determining the extent to which these cells are sensitive to killing by human gammadelta-T cells. Accordingly, in ongoing and future clinical studies using gammadelta-T cells for the treatment of a variety of epithelial-derived solid tumors-including pancreatic cancer-interventions intended to modulate ICAM expression on tumor cells may become important adjuncts to gammadelta-T-cell-based immunotherapies.

Protective immunosurveillance and therapeutic antitumor activity of gammadelta T cells demonstrated in a mouse model of prostate cancer.

In contrast to Ag-specific alphabeta T cells, gammadelta T cells can kill malignantly transformed cells in a manner that does not require the recognition of tumor-specific Ags. Although such observations have contributed to the emerging view that gammadelta T cells provide protective innate immunosurveillance against certain malignancies, particularly those of epithelial origin, they also provide a rationale for developing novel clinical approaches to exploit the innate antitumor properties of gammadelta T cells for the treatment of cancer. Using TRAMP, a transgenic mouse model of prostate cancer, proof-of-concept studies were performed to first establish that gammadelta T cells can indeed provide protective immunosurveillance against spontaneously arising mouse prostate cancer. TRAMP mice, which predictably develop prostate adenocarcinoma, were backcrossed with gammadelta T cell-deficient mice (TCRdelta(-/-) mice) yielding TRAMP x TCRdelta(-/-) mice, a proportion of which developed more extensive disease compared with control TRAMP mice. By extension, these findings were then used as a rationale for developing an adoptive immunotherapy model for treating prostate cancer. Using TRAMP-C2 cells derived from TRAMP mice (C57BL/6 genetic background), disease was first established in otherwise healthy wild-type C57BL/6 mice. In models of localized and disseminated disease, tumor-bearing mice treated i.v. with supraphysiological numbers of syngeneic gammadelta T cells (C57BL/6-derived) developed measurably less disease compared with untreated mice. Disease-bearing mice treated i.v. with gammadelta T cells also displayed superior survival compared with untreated mice. These findings provide a biological rationale for clinical trials designed to adoptively transfer ex vivo expanded autologous gammadelta T cells for the treatment of prostate cancer.

[Analysis of bacterial diversity of kefir grains by denaturing gradient gel electrophoresis and 16S rDNA sequencing].

Kefir is an acidic, mildly alcoholic dairy beverage produced by the fermentation of milk with a grain-like starter culture. These grains usually contain a relatively stable and specific balance of microbes that exist in a complex symbiotic relationship. Kefir grains can be considered a probiotic source as it presents anti-bacterial, anti-mycotic, anti-neoplasic and immunomodulatory properties. The microorganisms in Kefir grains are currently identified by traditional methods such as growth on selective media, morphological and biochemical characteristics. However, the microorganisms that isolate by these methods can not revert to Kefir grains which indicate that there are some other bacteria that are not isolate from it. In this study, PCR-based Denaturing gradient gel electrophoresis(DGGE) and sequence analysis of 16S ribosomal RNA gene (16S rDNA) clone libraries was used for the rapid and accurate identification of microorganisms from Kefir grains. The PCR primers were designed from conserved nucleotide sequences on region V3 of 16S rDNA with GC rich clamp at the 5'-end. PCR was performed using the primers and genomic DNAs of Kefir grains bacteria. The generated region V3 of 16S rDNA fragments were separated by denaturing gel, and the dominant 16S rDNA bands were cloned, sequenced and subjected to an online similarity search. Research has shown that regions V3 of 16S rDNAs have eight evident bands on the DGGE gel. The sequence analysis of these eight bands has indicated that they belong to different four genera, among them three sequences are similar to Sphingobacterium sp. whose similarities with database sequences are over 98%, three sequences are similar to Lactobacillus sp. whose similarities with database sequences are over 96%, the other two sequence are similar to Enterobacter sp., and Acinetobacter sp. whose similarities with database sequences are over 99% respectively. Although the DGGE method may have a lower sensitivity than the ordinary PCR methods, because when universal bacterial PCR primers are used, only the dominant microbiota of an ecosystem will be visualized on a DGGE gel, producing complex banding patterns. However, it could visualize the bacterial qualitative compositions and reveal the major species of the Kefir grains. Among them Sphingobacterium can be found in Kefir grains as the predominant flora which is reported for the first time. PCR-based DGGE and sequence analysis of 16S rDNA proved to be a valuable culture-independent approach for the rapid and specific identification of the microbial species present in microecosystem and probiotic products.

Innate anti-breast cancer immunity of apoptosis-resistant human gammadelta-T cells.

We previously identified a CD2-initiated signaling pathway which inhibits activation-induced cell death in mitogen-stimulated human gammadelta-T cells permitting the large-scale expansion of these cells. Here we report the innate anti-tumor activity of expanded human gammadelta-T cells against human breast cancer cells. Apoptosis-resistant human gammadelta-T cells which were expanded in vitro from cultured human peripheral blood mononuclear cells displayed lytic activity against breast cancer cell lines MDA-MB-231, MCF-7 and T-47D, but failed to kill normal human skin fibroblasts and normal human liver cells. Monoclonal antibodies (mAb) directed against the gammadelta-T cell receptor (TCR) or mAb directed against either the Vgamma9 or the Vdelta2 TCR chains were able to block gammadelta-T cell-mediated lysis of MDA-MB-231 cells. In addition, mAb against intercellular adhesion molecules-1 (ICAM-1/CD54) or CD18 (beta subunit of ICAM-1 counter-receptor) also blocked gammadelta-T cell-mediated killing of MDA-MB-231 cells. Ex vivo expanded human gammadelta-T cells are thus able to innately recognize and kill human breast cancer cells in a gammadelta-TCR-dependent manner; ICAM-1 and CD18 also appear to be involved in the interactions between sensitive breast cancer cells and cytolytic gammadelta-T cells. As apoptosis-resistant human gammadelta-T cells can now readily be expanded to large numbers (clinical scale), these findings must be considered in the context of developing adoptive immunotherapy strategies to exploit gammadelta-T cell innate immune responses for the primary or adjuvant treatment of breast cancer.

Ex vivo expanded human Vgamma9Vdelta2+ gammadelta-T cells mediate innate antitumor activity against human prostate cancer cells in vitro.

PURPOSE: We have previously identified a CD2 mediated, interleukin-12 dependent signaling pathway that inhibits activation induced cell death in mitogen stimulated human gammadelta-T cells, permitting the large-scale expansion of these cells. Herein we report the innate antitumor activity of expanded human Vgamma9Vdelta2+ gammadelta-T cells against human prostate cancer cells. MATERIALS AND METHODS: Apoptosis resistant human gammadelta-T cells were expanded in vitro from cultured human peripheral blood mononuclear cells and then enriched to high purity by immunomagnetic separation. In vitro cytotoxicity of expanded gammadelta-T cells was measured against human prostate cancer cell lines using standard cytotoxicity assays. RESULTS: gammadelta-T cells derived from various donors consistently showed lytic activity against the prostate cancer cell lines DU-145 and PC-3 but not LNCaP. mAbs against Vgamma9 or Vdelta2 T-cell receptor chains as well as mAb against intercellular adhesion molecule-1 (ICAM-1) or CD18, the beta subunit of ICAM-1 counter receptors, blocked gammadelta-T cell mediated killing of prostate cancer cells. gammadelta-T cells lysed prostate cancer cell lines largely through the perforin/granzyme pathway. CONCLUSIONS: Ex vivo, expanded human Vgamma9Vdelta2+ gammadelta-T cells are able innately to recognize and kill certain human prostate tumor cell lines in vitro. The recognition and killing of prostate cancer cells occurs in a gammadelta-T-cell receptor dependent manner and it also appears to involve interactions between ICAM-1 and CD18. Because apoptosis resistant human Vgamma9Vdelta2+ gammadelta-T cells can readily be expanded to large numbers (clinical scale), these findings must be considered in the context of developing adoptive immunotherapy strategies to exploit gammadelta-T cell innate immune responses to prostate cancer.

Down-regulation of IL-2 receptor alpha (CD25) characterizes human gammadelta-T cells rendered resistant to apoptosis after CD2 engagement in the presence of IL-12.

We recently identified a CD2-mediated, IL-12-dependent signaling pathway that inhibits apoptosis in mitogen-stimulated human gammadelta-T cells. Here we show that gammadelta-T cells which acquire resistance to mitogen-induced apoptosis upregulate IL-12 receptor beta 1 subunit (IL-12Rbeta1); in contrast, gammadelta-T cells which remain sensitive to mitogen-induced apoptosis fail to express IL-12Rbeta1. Next we show that gammadelta-T cells which are rendered resistant to mitogen-induced apoptosis attenuate their expression of the IL-2 receptor alpha chain (IL-2Ralpha/CD25), this in part accounting for their acquired resistance to IL-2-induced death. In contrast, apoptosis-sensitive gammadelta-T cells are shown to persist in their expression of IL-2Ralpha/CD25, thus remaining sensitive to IL-2-induced death. Moreover, we show that apoptosis-resistant, but not apoptosis-sensitive, gammadelta-T cells display an enhanced responsiveness to IL-15, a finding in keeping with the known function of IL-15 as a growth and survival factor. Finally, we present evidence to suggest that this differential responsiveness to IL-15 occurs in part by the increased expression of the IL-15Ralpha chain on apoptosis-resistant gammadelta-T cells, compared to apoptosis-sensitive gammadelta-T cells. The biological and clinical implications of these findings are discussed.