Calcium gluconate-based flame retardant towards simultaneously high-efficiency fire safety and mechanical enhancement for epoxy resin

Flame retardants containing biomass receive growing interest in environmental friendliness and sustainability but usually face the low flame-retardant efficiency and deterioration on mechanical property of matrix. Herein, a calcium gluconate-based flame retardant (CG@APP) was chemically prepared using calcium gluconate (CG) and ammonium polyphosphate (APP) via ion exchange reaction, and enabled the excellent fire safety and mechanical enhancement for epoxy resin (EP). The resulted EP composites containing 6 wt% CG@APP (EP/CG@APP6) exhibited V-0 ratings in UL-94 test. Furthermore, with respect to EP/APP6, the peak of heat release rate (pHRR) and peak of smoke production rate (pSPR) of EP/CG@APP6 decreased by 70.5 % and 50.0 %, respectively. The well synergistic flame-retardant mechanism of CG@APP between gaseous and solid phases was revealed to generate denser and more continuous charring residuals, which could do well work on insulation for heat transfer and fuel diffusion. In addition, the shell rich in hydroxyl group and Ca2+ on the surface of CG@APP well enhanced the interface compatibility through the hydrogen bond and coordinated bond, thus the tensile strength, flexural strength and impact strength of EP/CG@APP6 increased by 18.2 %, 4.5 % and 9.1 % compared with pure EP, respectively. This work provided a simple and sustainable way to construct excellent fire-safety composites.

Gram-level NH3 Electrosynthesis via NOx reduction on a Cu Activated Co Electrode

Ambient electrochemical ammonia (NH3 ) synthesis is one promising alternative to the energy-intensive Haber-Bosch route. However, the industrial requirement for the electrochemical NH3 production with amperes current densities or gram-level NH3 yield remains a grand challenge. Herein, we report the high-rate NH3 production via NO2 - reduction using the Cu activated Co electrode in a bipolar membrane (BPM) assemble electrolyser, wherein BPM maintains the ion balance and the liquid level of electrolyte. Benefited from the abundant Co sites and optimal structure, the target modified Co foam electrode delivers a current density of 2.64 A cm-2 with the Faradaic efficiency of 96.45 % and the high NH3 yield rate of 279.44 mg h-1  cm-2 in H-type cell using alkaline electrolyte. Combined with in situ experiments and theoretical calculations, we found that Cu optimizes the adsorption behavior of NO2 - and facilitates the hydrogenation steps on Co sites toward a rapid NO2 - reduction process. Importantly, this activated Co electrode affords a large NH3 production up to 4.11 g h-1 in a homemade reactor, highlighting its large-scale practical feasibility.

A Bifunctional Catalyst for Green Ammonia Synthesis from Ubiquitous Air and Water

Ammonia (NH3 ) is essential for modern agriculture and industry, and, due to its high hydrogen density and no carbon emission, it is also expected to be the next-generation of "clean" energy carrier. Herein, directly from air and water, a plasma-electrocatalytic reaction system for NH3 production, which combines two steps of plasma-air-to-NOx - and electrochemical NOx - reduction reaction (eNOx RR) with a bifunctional catalyst, is successfully established. Especially, the bifunctional catalyst of CuCo2 O4 /Ni can simultaneously promote plasma-air-to-NOx - and eNOx RR processes. The easy adsorption and activation of O2 by CuCo2 O4 /Ni greatly improve the NOx - production rate at the first step. Further, CuCo2 O4 /Ni can also resolve the overbonding of the key intermediate of * NO, and thus reduce the energy barrier of the second step of eNOx RR. Finally, the "green" NH3 production achieves excellent FENH3 (96.8%) and record-high NH3 yield rate of 145.8 mg h-1  cm-2 with large partial current density (1384.7 mA cm-2 ). Moreover, an enlarged self-made H-type electrolyzer improves the NH3 yield to 3.6 g h-1 , and the obtained NH3 is then rapidly converted to a solid of magnesium ammonium phosphate hexahydrate, which favors the easy storage and transportation of NH3 .

Chromosomal abnormalities and neurological outcomes in fetal cerebral ventriculomegaly: a retrospective cohort analysis

INTRODUCTION

This study investigated the incidences of chromosomal abnormalities and the neurological outcomes according to the degree of fetal cerebral ventriculomegaly.

METHODS

All women with antenatal ultrasound diagnosis of fetal cerebral ventriculomegaly were retrospectively identified from two maternal-fetal medicine units in Hong Kong from January 2014 to December 2018. Degrees of fetal ventriculomegaly were classified as mild (10-11.9 mm), moderate (12-14.9 mm), or severe (≥15 mm). Genetic investigation results were reviewed, including conventional karyotyping and chromosomal microarray analysis (CMA); correlations between chromosomal abnormalities and the degree of fetal ventriculomegaly were explored. The neurological outcomes of subsequent live births were analysed to identify factors associated with developmental delay.

RESULTS

Of 84 cases (ie, pregnant women and their fetuses) included, 46 (54.8%) exhibited isolated fetal ventriculomegaly, 55 (65.5%) had mild cerebral ventriculomegaly, and 29 (34.5%) had moderate or severe cerebral ventriculomegaly. Overall, 20% (14/70) of cases had chromosomal abnormalities. Moreover, 12% (3/25) of mild isolated ventriculomegaly cases had abnormal karyotype or CMA results. The CMA provided an incremental diagnostic yield of 8.6% (6/70), compared with conventional karyotyping; 4.3% exhibited pathogenic variants and 4.3% exhibited variants of uncertain significance. Among the 53 live births in the cohort, fewer cases of mild isolated ventriculomegaly were associated with developmental delay than more severe isolated ventriculomegaly (9.7% vs 41.7%, P<0.03).

CONCLUSIONS

Chromosomal microarray analysis testing should be offered to all women with fetal cerebral ventriculomegaly, including women with isolated mild ventriculomegaly. The incidence of developmental delay after birth increases with the degree of prenatal cerebral ventriculomegaly.

Expanded carrier screening using next-generation sequencing of 123 Hong Kong Chinese families: a pilot study

INTRODUCTION

To determine the carrier frequency and common mutations of Mendelian variants in Chinese couples using next-generation sequencing (NGS).

METHODS

Preconception expanded carrier testing using NGS was offered to women who attended the subfertility clinic. The test was then offered to the partners of women who had positive screening results. Carrier frequency was calculated, and the results of the NGS panel were compared with those of a target panel.

RESULTS

One hundred twenty-three women and 20 of their partners were screened. Overall, 84 (58.7%) individuals were identified to be carriers of at least one disease, and 68 (47.6%) were carriers after excluding thalassaemias. The most common diseases found were GJB2-related DFNB1 nonsyndromic hearing loss and deafness (1 in 4), alpha-thalassaemia (1 in 7), beta-thalassaemia (1 in 14), 21-hydroxylase deficient congenital adrenal hyperplasia (1 in 13), Pendred's syndrome (1 in 36), Krabbe's disease (1 in 48), and spinal muscular atrophy (1 in 48). Of the 43 identified variants, 29 (67.4%) were not included in the American College of Medical Genetics and Genomics or American College of Obstetrics and Gynecology guidelines. Excluding three couples with alpha-thalassaemia, six at-risk couples were identified.

CONCLUSION

The carrier frequency of the investigated members of the Chinese population was 58.7% overall and 47.6% after excluding thalassaemias. This frequency is higher than previously reported. Expanded carrier screening using NGS should be provided to Chinese people to improve the detection rate of carrier status and allow optimal pregnancy planning.

Hybrid solid electrolyte enabled dendrite-free Li anodes for high-performance quasi-solid-state lithium-oxygen batteries

The dendrite growth of Li anodes severely degrades the performance of lithium-oxygen (Li-O₂) batteries. Recently, hybrid solid electrolyte (HSE) has been regarded as one of the most promising routes to tackle this problem. However, before this is realized, the HSE needs to simultaneously satisfy contradictory requirements of high modulus and even, flexible contact with Li anode, while ensuring uniform Li⁺ distribution. To tackle this complex dilemma, here, an HSE with rigid Li_1.5Al_0.5Ge_1.5(PO₄)₃ (LAGP) core@ultrathin flexible poly (vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) shell interface has been developed. The introduced large amount of nanometer-sized LAGP cores can not only act as structural enhancer to achieve high Young's modulus but can also construct Li⁺ diffusion network to homogenize Li⁺ distribution. The ultrathin flexible PVDF-HFP shell provides soft and stable contact between the rigid core and Li metal without affecting the Li⁺ distribution, meanwhile suppressing the reduction of LAGP induced by direct contact with Li metal. Thanks to these advantages, this ingenious HSE with ultra-high Young's modulus of 25 GPa endows dendrite-free Li deposition even at a deposition capacity of 23.6 mAh. Moreover, with the successful inhibition of Li dendrites, the HSE-based quasi-solid-state Li-O₂ battery delivers a long cycling stability of 146 cycles, which is more than three times that of gel polymer electrolyte-based Li-O₂ battery. This new insight may serve as a starting point for further designing of HSE in Li-O₂ batteries, and can also be extended to various battery systems such as sodium-oxygen batteries.

Effects of sarcopenia, hypoalbuminemia, and laparoscopic surgery on postoperative complications in elderly patients with colorectal cancer: A prospective study

With the increasing number of elderly patients, the risk of diseases such as colorectal cancer (CRC) has increased. The objective of this prospective study was to explore the effects of sarcopenia, hypoalbuminemia, and laparoscopic surgery on postoperative complications among elderly patients who recently underwent colorectal surgery. Patients aged over 65 years who underwent surgery for CRC at the First Affiliated Hospital of Wenzhou Medical University were considered for this study. The demographical and clinical characteristics of these patients, as well as postoperative complications, were prospectively analyzed. The patients were divided into two groups depending on the diagnosis of sarcopenia, and the clinical variables corresponding to the two groups were compared. Further, the risk factors associated with postoperative complications were evaluated using univariate analysis and multivariate logistic regression analysis. A total of 360 patients fulfilled the inclusion criteria. Incidences of postoperative complications in the sarcopenia and non-sarcopenia groups were at 38.3% and 27.3%, respectively. In addition, sarcopenia (p=0.029) and hypoalbuminemia (p=0.010) were identified as independent risk factors, while laparoscopic surgery (p=0.023) was identified as a protective factor for postoperative complications. However, laparoscopic surgery was a protective factor for postoperative complications in the colon group only (p=0.001). Sarcopenia and hypoalbuminemia are independent risk factors that influence the probability of developing complications following CRC surgery. Laparoscopic surgery is a protective factor for postoperative complications of CRC patients, particularly colon cancer patients.

Chloroplast genome structure and phylogenetic position of Ruppia sinensis Shuo Yu & den Hartog

Ruppia is widely distributed in marine and inland saline habitats in temperate and tropical regions. In this study, the complete chloroplast genome sequence of R. sinensis was successfully obtained using Illumina sequencing. The full length of the chloroplast genome length was 158,897 bp with a typical quadripartite structure: one large single copy (LSC) region (88,952 bp), one small single copy (SSC) region (19,047 bp), and a pair of inverted repeats (IR) (25,449 bp each). The GC content of this genome was 35.9%. The whole genome contained 136 genes, including 88 protein-coding genes, 40 tRNA genes, and eight rRNA genes. Phylogenetic analysis indicated that R. sinensis formed a distinct clade, being separated from Zostera marina and Potamogeton perfoliatus.

Generating Defect-Rich Bismuth for Enhancing the Rate of Nitrogen Electroreduction to Ammonia

The electrochemical N₂ fixation, which is far from practical application in aqueous solution under ambient conditions, is extremely challenging and requires a rational design of electrocatalytic centers. We observed that bismuth (Bi) might be a promising candidate for this task because of its weak binding with H adatoms, which increases the selectivity and production rate. Furthermore, we successfully synthesized defect-rich Bi nanoplates as an efficient noble-metal-free N₂ reduction electrocatalyst via a low-temperature plasma bombardment approach. When exclusively using ¹ H NMR measurements with N₂ gas as a quantitative testing method, the defect-rich Bi(110) nanoplates achieved a ¹⁵ NH₃ production rate of 5.453 μg mg_Bi ^-1  h^-1 and a Faradaic efficiency of 11.68 % at -0.6 V vs. RHE in aqueous solution at ambient conditions.

Recent Advances toward the Rational Design of Efficient Bifunctional Air Electrodes for Rechargeable Zn-Air Batteries

Large-scale application of renewable energy and rapid development of electric vehicles have brought unprecedented demand for advanced energy-storage/conversion technologies and equipment. Rechargeable zinc (Zn)-air batteries represent one of the most promising candidates because of their high energy density, safety, environmental friendliness, and low cost. The air electrode plays a key role in managing the many complex physical and chemical processes occurring on it to achieve high performance of Zn-air batteries. Herein, recent advances of air electrodes from bifunctional catalysts to architectures are summarized, and their advantages and disadvantages are discussed to underline the importance of progress in the evolution of bifunctional air electrodes. Finally, some challenges and the direction of future research are provided for the optimized design of bifunctional air electrodes to achieve high performance of rechargeable Zn-air batteries.

Amorphizing of Au Nanoparticles by CeOx -RGO Hybrid Support towards Highly Efficient Electrocatalyst for N2 Reduction under Ambient Conditions

Ammonia synthesis is one of the most kinetically complex and energetically challenging chemical processes in industry and has used the Harber-Bosch catalyst for over a century, which is processed under both harsh pressure (150-350 atm) and hightemperature (623-823 K), wherein the energy and capital intensive Harber-Bosch process has a huge energy cost accounting for about 1%-3% of human's energy consumption. Therefore, there has been a rough and vigorous exploration to find an environmentally benign alternative process. As the amorphous material is in a metastable state and has many "dangling bonds", it is more active than the crystallized one. In this paper, CeO_x -induced amorphization of Au nanoparticles anchored on reduced graphite oxide (a-Au/CeO_x -RGO) has been achieved by a facile coreduction method under ambient atmosphere. As a proof-of-concept experiment, a-Au/CeO_x -RGO hybrid catalyst containing the low noble metal (Au loading is 1.31 wt%) achieves a high Faradaic efficiency (10.10%) and ammonia yield (8.3 μg h^-1 mg^-1_cat. ) at -0.2 V versus RHE, which is significantly higher than that of the crystalline counterpart (c-Au/RGO), and even comparable to the yields and efficiencies under harsh temperatures and/or pressures.

Au Sub-Nanoclusters on TiO2 toward Highly Efficient and Selective Electrocatalyst for N2 Conversion to NH3 at Ambient Conditions

As the NN bond in N₂ is one of the strongest bonds in chemistry, the fixation of N₂ to ammonia is a kinetically complex and energetically challenging reaction and, up to now, its synthesis is still heavily relying on energy and capital intensive Haber-Bosch process (150-350 atm, 350-550 °C), wherein the input of H₂ and energy are largely derived from fossil fuels and thus result in large amount of CO₂ emission. In this paper, it is demonstrated that by using Au sub-nanoclusters (≈0.5 nm ) embedded on TiO₂ (Au loading is 1.542 wt%), the electrocatalytic N₂ reduction reaction (NRR) is indeed possible at ambient condition. Unexpectedly, NRR with very high and stable production yield (NH₃ : 21.4 µg h^-1 mg^-1_cat. , Faradaic efficiency: 8.11%) and good selectivity is achieved at -0.2 V versus RHE, which is much higher than that of the best results for N₂ fixation under ambient conditions, and even comparable to the yield and activation energy under high temperatures and/or pressures. As isolated precious metal active centers dispersed onto oxide supports provide a well-defined system, the special structure of atomic Au cluster would promote other important reactions besides NRR for water splitting, fuel cells, and other electrochemical devices.

Electrochemical Reduction of N2 under Ambient Conditions for Artificial N2 Fixation and Renewable Energy Storage Using N2 /NH3 Cycle

Using tetrahexahedral gold nanorods as a heterogeneous electrocatalyst, an electrocatalytic N₂ reduction reaction is shown to be possible at room temperature and atmospheric pressure, with a high Faradic efficiency up to 4.02% at -0.2 V vs reversible hydrogen electrode (1.648 µg h^-1 cm^-2 and 0.102 µg h^-1 cm^-2 for NH₃ and N₂ H₄ ·H₂ O, respectively).

[Levels of dichlorodiphenyltrichloroethane internal exposure levels in pregnant women of Xiamen and influencing factors]

Objective: To investigate the level of and factors influencing internal exposure to dichlorodiphenyltrichloroethane (DDT) in pregnant women. Methods: In all, 1 064 pregnant women were recruited in a hospital of Xiamen. Participants were asked to complete a questionnaire to obtain data on sociodemographic characteristics and lifestyle. Peripheral venous blood and cord blood samples were collected. Of the 1 064 pregnant women, 600 were enrolled in this study after completing the questionnaire and providing peripheral venous blood and cord blood. Among those women, 150 were selected randomly using a systematic sampling method. A gas chromatography coupled electron capture detector was used to determine the concentration of six DDT homologues: p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT), o,p'-dichlorodiphenyltrichloroethane (o,p'-DDT), p,p'-dichlorodiphenyldichloroethane (p,p'-DDD), o,p'-dichlorodiphenyldichloroethane (o,p'-DDD), p,p'-dichlorodiphenylethylene (p,p'-DDE), and o,p'-dichlorodiphenylethylene (o,p'-DDE) . Pregnant women were divided into two groups according to DDT concentration: a low concentration group (detection value≤P₅₀) and a high concentration group (detection value>P₅₀). multivariate logistic regression was used to analyze the association between the DDT levels and potential influencing factors which investigated in the questionnaire. Results: The detection rates of p,p'-DDT, o,p'-DDT, p,p'-DDD, o,p'-DDD, p,p'-DDE and o,p'-DDE in the peripheral venous blood samples from the 150 pregnant women were 83.3% (125), 29.3% (44), 58.0% (87), 24.0% (36), 82.0% (123), and 34.7% (52), respectively. The median concentrations were 1.56, 0.03, 0.07, 0.03, 0.93 and 0.03 μg/ml, respectively. The detection rates of p,p'-DDT, o,p'-DDT, p,p'-DDD, o,p'-DDD, p,p'-DDE and o,p'-DDE in the cord blood samples were 69.3% (104), 10.7% (16), 29.3% (44), 20.7% (31), 81.3% (122) and 45.3% (68), and the median concentrations were 0.41, 0.03, 0.03, 0.03, 0.42 and 0.03 μg/ml, respectively. The concentration ranges in the low and high DDT concentration groups which contained 75 respondents respectively were 0-3.69 and 3.74-82.09 μg/ml, respectively. In the single-factor analysis, the number (percentage) of those who consumed seafood " rarely" , "less than twice a week" , and " twice a week or more" was 15 (20.3%), 22 (29.7%), and 37 (50.0%), respectively, in the low concentration group, and 4(5.3%), 20(26.7% ), and 51(68.0% ) in the high concentration group (χ²=8.69, P=0.013). The results of the multivariate logistic regression analysis indicate that pregnant women who consume seafood less than twice a week, twice a week or more have higher peripheral blood DDT concentrations compared with those who rarely consume seafood. The OR (95% CI) values were 1.14 (1.08-1.21), 2.11 (1.55-2.85), respectively. Conclusion: The exposure level of pregnant women to DDTs in the Xiamen area is higher than that of women in other regions. High seafood intake is a risk factor for internal exposure to DDTs.

Habitat loss other than fragmentation per se decreased nuclear and chloroplast genetic diversity in a monoecious tree

Generally, effect of fragmentation per se on biodiversity has not been separated from the effect of habitat loss. In this paper, using nDNA and cpDNA SSRs, we studied genetic diversity of Castanopsis sclerophylla (Lindl. & Paxton) Schotty populations and decoupled the effects of habitat loss and fragmentation per se. We selected seven nuclear and six cpDNA microsatellite loci and genotyped 460 individuals from mainland and island populations, which were located in the impoundment created in 1959. Number of alleles per locus of populations in larger habitats was significantly higher than that in smaller habitats. There was a significant relationship between the number of alleles per locus and habitat size. Based on this relationship, the predicted genetic diversity of an imaginary population of size equaling the total area of the islands was lower than that of the global population on the islands. Re-sampling demonstrated that low genetic diversity of populations in small habitats was caused by unevenness in sample size. Fisher's α index was similar among habitat types. These results indicate that the decreased nuclear and chloroplast genetic diversity of populations in smaller habitats was mainly caused by habitat loss. For nuclear and chloroplast microsatellite loci, values of F_ST were 0.066 and 0.893, respectively, and the calculated pollen/seed dispersal ratio was 162.2. When separated into pre-and post-fragmentation cohorts, pollen/seed ratios were 121.2 and 189.5, respectively. Our results suggest that habitat loss explains the early decrease in genetic diversity, while fragmentation per se may play a major role in inbreeding and differentiation among fragmented populations and later loss of genetic diversity.

Intratumoral expression profiling of genes involved in angiogenesis in colorectal cancer patients treated with chemotherapy plus the VEGFR inhibitor PTK787/ZK 222584 (vatalanib)

The phase III CONFIRM clinical trials demonstrated that metastatic colorectal cancer patients with elevated serum lactate dehydrogenase (LDH) had improved outcome when the vascular endothelial growth factor receptor (VEGFR) inhibitor PTK/ZK (Vatalanib) was added to FOLFOX4 chemotherapy. We investigated the hypothesis that high intratumoral expression of genes regulated by hypoxia-inducible factor-1 alpha (HIF1α), namely LDHA, glucose transporter-1 (GLUT-1), VEGFA, VEGFR1, and VEGFR2, were predictive of outcome in CONFIRM-1. Tumor tissue was isolated by laser-capture microdissection from 85 CONFIRM-1 tumor specimens; FOLFOX4/placebo n=42, FOLFOX4/PTK/ZK n=43. Gene expression was analyzed using quantitative RT-PCR. In univariate analyses, elevated mRNA expression of LDHA, GLUT-1, and VEGFR1 were associated with response to FOLFOX4/PTK/ZK. In univariate and multivariate analyses, elevated LDHA and VEGFR1 mRNA levels were associated with improved progression-free survival in FOLFOX4/PTK/ZK patients. Furthermore, increased HIF1α and VEGFR2 mRNA levels were associated with decreased survival in FOLFOX/placebo patients but not in patients who received FOLFOX4/PTK/ZK. These are the first data suggesting intratumoral mRNA expression of genes involved in angiogenesis/HIF pathway may predict outcome to VEGFR-inhibitors. Biomarkers that assist in directing VEGFR-inhibitors toward patients with an increased likelihood of benefit will improve the cost-effectiveness of these promising agents.

Isolation by elevation: genetic structure at neutral and putatively non-neutral loci in a dominant tree of subtropical forests, Castanopsis eyrei

Background

The distribution of genetic diversity among plant populations growing along elevational gradients can be affected by neutral as well as selective processes. Molecular markers used to study these patterns usually target neutral processes only, but may also be affected by selection. In this study, the effects of elevation and successional stage on genetic diversity of a dominant tree species were investigated controlling for neutrality of the microsatellite loci used.

Methodology/Principal Findings

Diversity and differentiation among 24 populations of Castanopsis eyrei from different elevations (251–920 m) and successional stages were analysed by eight microsatellite loci. We found that one of the loci (Ccu97H18) strongly deviated from a neutral model of differentiation among populations due to either divergent selection or hitchhiking with an unknown selected locus. The analysis showed that C. eyrei populations had a high level of genetic diversity within populations (A_R = 7.6, H_E = 0.82). Genetic variation increased with elevation for both the putatively selected locus Ccu97H18 and the neutral loci. At locus Ccu97H18 one allele was dominant at low elevations, which was replaced at higher elevations by an increasing number of other alleles. The level of genetic differentiation at neutral loci was similar to that of other Fagaceae species (F_ST = 0.032,  = 0.15). Population differentiation followed a model of isolation by distance but additionally, strongly significant isolation by elevation was found, both for neutral loci and the putatively selected locus.

Conclusions/Significance

The results indicate higher gene flow among similar elevational levels than across different elevational levels and suggest a selective influence of elevation on the distribution of genetic diversity in C. eyrei. The study underlines the importance to check the selective neutrality of marker loci in analyses of population structure.

Regulatory effects of eotaxin on acute lung inflammatory injury

Eotaxin, which is a major mediator for eosinophil recruitment into lung, has regulatory effects on neutrophil-dependent acute inflammatory injury triggered by intrapulmonary deposition of IgG immune complexes in rats. In this model, eotaxin mRNA and protein were up-regulated during the inflammatory response, resulting in eotaxin protein expression in alveolar macrophages and in alveolar epithelial cells. Ab-induced blockade of eotaxin in vivo caused enhanced NF-kappaB activation in lung, substantial increases in bronchoalveolar lavage levels of macrophage inflammatory protein (MIP)-2 and cytokine-induced neutrophil chemoattractant (CINC), and increased MIP-2 and CINC mRNA expression in alveolar macrophages. In contrast, TNF-alpha levels were unaffected, and IL-10 levels fell. Under these experimental conditions, lung neutrophil accumulation was significantly increased, and vascular injury, as reflected by extravascular leak of (125)I-albumin, was enhanced. Conversely, when recombinant eotaxin was administered in the same inflammatory model of lung injury, bronchoalveolar lavage levels of MIP-2 were reduced, as was neutrophil accumulation and the intensity of lung injury. In vitro stimulation of rat alveolar macrophages with IgG immune complexes greatly increased expression of mRNA and protein for MIP-2, CINC, MIP-1alpha, MIP-1beta, TNF-alpha, and IL-1beta. In the copresence of eotaxin, the increased levels of MIP-2 and CINC mRNAs were markedly diminished, whereas MIP-1alpha, MIP-1beta, TNF-alpha, and IL-1beta expression of mRNA and protein was not affected. These data suggest that endogenous eotaxin, which is expressed during the acute lung inflammatory response, plays a regulatory role in neutrophil recruitment into lung and the ensuing inflammatory damage.

Pharmacogenetic application in drug development and clinical trials

Pharmacogenetics examines the genetic characteristics of individuals to understand variations in response to therapeutics. This approach has the potential to significantly affect the development of new medicines. The application of pharmacogenetic principles could yield significant time and resource savings within the drug development process. In preclinical drug development, pharmacogenetics could be applied to compound screening and identifying potential side effects before entering full clinical testing. Subpopulations of patients with different drug responses and underlying genetic markers could be stratified in clinical trials by analyzing their genotype. These data can improve clinical trial design and offer the possibility of optimized drug prescription based on patient genotype. Pharmacogenetics can guide the development of therapeutic interventions by identifying nonresponder patient groups. Advances in high-throughput genotyping technologies have added potential by facilitating the technical hurdles and improving drug development strategies, clinical trial design, and postmarket pharmaco-vigilance. Pharmacogenetics, thus, impacts all phases of drug development and will fundamentally change the practice of medicine in the near future.

Molecular cloning and characterization of DEFCAP-L and -S, two isoforms of a novel member of the mammalian Ced-4 family of apoptosis proteins

We report the deduced amino acid sequences of two alternately spliced isoforms, designated DEFCAP-L and -S, that differ in 44 amino acids and encode a novel member of the mammalian Ced-4 family of apoptosis proteins. Similar to the other mammalian Ced-4 proteins (Apaf-1 and Nod1), DEFCAP contains a caspase recruitment domain (CARD) and a putative nucleotide binding domain, signified by a consensus Walker's A box (P-loop) and B box (Mg(2+)-binding site). Like Nod1, but different from Apaf-1, DEFCAP contains a putative regulatory domain containing multiple leucine-rich repeats (LRR). However, a distinguishing feature of the primary sequence of DEFCAP is that DEFCAP contains at its NH(2) terminus a pyrin-like motif and a proline-rich sequence, possibly involved in protein-protein interactions with Src homology domain 3-containing proteins. By using in vitro coimmunoprecipitation experiments, both long and short isoforms were capable of strongly interacting with caspase-2 and exhibited a weaker interaction with caspase-9. Transient overexpression of full-length DEFCAP-L, but not DEFCAP-S, in breast adenocarcinoma cells MCF7 resulted in significant levels of apoptosis. In vitro death assays with transient overexpression of deletion constructs of both isoforms using beta-galactosidase as a reporter gene in MCF7 cells suggest the following: 1) the nucleotide binding domain may act as a negative regulator of the killing activity of DEFCAP; 2) the LRR/CARD represents a putative constitutively active inducer of apoptosis; 3) the killing activity of LRR/CARD is inhibitable by benzyloxycarbonyl-Val-Ala-Asp (OMe)-fluoromethyl ketone and to a lesser extent by Asp-Glu-Val-Asp (OMe)-fluoromethyl ketone; and 4) the CARD is critical for killing activity of DEFCAP. These results suggest that DEFCAP is a novel member of the mammalian Ced-4 family of proteins capable of inducing apoptosis, and understanding its regulation may elucidate the complex nature of the mammalian apoptosis-promoting machinery.

Enabling large-scale pharmacogenetic studies by high-throughput mutation detection and genotyping technologies

BACKGROUND

Pharmacogenetics is a scientific discipline that examines the genetic basis for individual variations in response to therapeutics. Pharmacogenetics promises to develop individualized medicines tailored to patients' genotypes. However, identifying and genotyping a vast number of genetic polymorphisms in large populations also pose a great challenge.

APPROACH

This article reviews the recent technology development in mutation detection and genotyping with a focus on genotyping of single nucleotide polymorphisms (SNPs).

CONTENT

Novel mutations/polymorphisms are commonly identified by conformation-based mutation screening and direct high-throughput heterozygote sequencing. With a large amount of public sequence information available, in silico SNP mapping has also emerged as a cost-efficient way for new polymorphism identification. Gel electrophoresis-based genotyping methods for known polymorphisms include PCR coupled with restriction fragment length polymorphism analysis, multiplex PCR, oligonucleotide ligation assay, and minisequencing. Fluorescent dye-based genotyping technologies are emerging as high-throughput genotyping platforms, including oligonucleotide ligation assay, pyrosequencing, single-base extension with fluorescence detection, homogeneous solution hybridization such as TaqMan, and molecular beacon genotyping. Rolling circle amplification and Invader assays are able to genotype directly from genomic DNA without PCR amplification. DNA chip-based microarray and mass spectrometry genotyping technologies are the latest development in the genotyping arena.

SUMMARY

Large-scale genotyping is crucial to the identification of the genetic make-ups that underlie the onset of diseases and individual variations in drug responses. Enabling technologies to identify genetic polymorphisms rapidly, accurately, and cost effectively will dramatically impact future drug and development processes.

Regulation of chemokine mRNA expression in a rat model of vanadium-induced pulmonary inflammation

Environmental and occupational exposure to vanadium dusts results in toxic effects mainly confined to the respiratory system. Using a rat model of acute lung inflammation induced by intratracheal instillation of sodium metavanadate (NaVO3) at the dose of 200 microg V/kg, we investigated the relationship between the cytologic characterization of pulmonary inflammation and the expression of chemokine mRNA. Significant polymorphonuclear leukocyte (PMN) influx (P < 0.01) into the lung was noted 4 h after NaVO3 instillation, whereas alveolar macrophages (AMs) in bronchoalveolar lavage (BAL) cells appeared to decrease significantly. In contrast, neither PMNs nor AMs changed substantially 1 h after NaVO3 instillation. By Northern analysis, macrophage inflammatory protein (MIP)-2 mRNA in BAL cells increased markedly 1 h after NaVO3 instillation and reduced a little bit at 4 h, whereas MIP-1alpha mRNA in BAL cells was expressed relatively high 1 h after NaVO3 instillation, although a basal expression was detected in control group, and returned rapidly nearly to control level at 4 h. Since MIP-2 is a potent PMN chemoattractant and MIP-1alpha is a potent macrophage/monocyte chemoattractant has been well known. The facts that PMN influx was preceded by increased MIP-2 mRNA expression, suggesting that MIP-2 is involved in the development of NaVO3-induced pulmonary inflammation, whereas increased MIP-1alpha mRNA expression was followed by decreased AMs in BAL cells, suggesting AMs might be activated by MIP-1alpha, adherent to the lining surface of the airways and then resistant to be washed out. To delineate the mechanisms of transcriptional activation, we recently cloned the 5'-flanking region of the MIP-2 gene. The promotor region contains consensus binding sites for transcription factor nuclear factor kappaB (NF-kappaB) and activator protein-1 (AP-1). Using electrophoretic mobility shift assay, increased nuclear NF-kappaB, not AP-1, binding activity was detected 1 h after NaVO3 instillation, which correlated with the induction of MIP-2 mRNA. p65 (Rel A) and p50 protein appears to be involved in MIP-2 NF-kappaB binding. Taken together, our studies suggest that MIP-2 is an important mediator of NaVO3-induced pulmonary inflammation in the rat model. In addition, elevated MIP-2 mRNA levels are accompanied by increased NF-kappaB binding activity in BAL cells, suggesting possible MIP-2 transcriptional regulation through NF-kappaB.

Protective effects of anti-C5a in sepsis-induced thymocyte apoptosis

Multiorgan apoptosis occurs during sepsis. Following cecal ligation and puncture (CLP) in rats, thymocytes underwent apoptosis in a time-dependent manner. C5a blockade dramatically reduced thymocyte apoptosis as measured by thymic weight, binding of annexin V to thymocytes, and laddering of thymocyte DNA. When C5a was generated in vivo by infusion of purified cobra venom factor (CVF), thymocyte apoptosis was significantly increased. Similar results were found when CVF was injected in vivo during the early stages of CLP. In animals 12 hours after induction of CLP, there was an increase in the activities of caspase-3, -6, and -9, but not caspase-1 and -8. Cytosolic cytochrome c levels increased by twofold, whereas mitochondrial levels showed a 50% decrease. Western blot analysis revealed that the content of Bcl-X(L) (but not of Bcl-2, BAX, Bad, and Bim) significantly decreased in thymocytes after CLP. C5a blockade in the sepsis model almost completely inhibited caspase-3, -6, and -9 activation, significantly preserved cytochrome c in the mitochondrial fraction, and restored Bcl-X(L) expression. These data suggest that systemic activation of complement induces C5a-dependent apoptosis of thymocytes and that the blockade of C5a during sepsis rescues thymocytes from apoptosis.

Eotaxin expression in Sephadex-induced lung injury in rats

The CC chemokine eotaxin is a potent and specific eosinophil chemoattractant. Eosinophil-dependent tissue injury has been shown to contribute to airway inflammation such as that in asthma. In the present study, We investigated eotaxin expression in a rat model of pulmonary inflammation (featuring accumulation of eosinophils) induced by intratracheal instillation of cross-linked dextran beads (Sephadex G200). Intratracheal instillation of 5 mg/kg Sephadex caused a time-dependent eosinophil infiltration into the lung, reaching a peak at 24 hours. Eotaxin mRNA in the lung paralleled the eosinophil influx. Eotaxin protein in bronchoalveolar (BAL) fluids and lung homogenates was shown by Western blot and immunostaining to be maximally expressed by 24 hours. Sephadex-induced lung injury, as measured by (125)I-labeled albumin leakage from the pulmonary vasculature, developed in a time-dependent manner. Intravenous injection of blocking antibody to eotaxin significantly decreased eosinophil infiltration and lung permeability. These data suggest that, in the Sephadex model of lung inflammation, eotaxin up-regulation mediates intrapulmonary accumulation of eosinophils and the development of lung injury.

Technologies for detecting genetic polymorphisms in pharmacogenomics

BACKGROUND

Pharmacogenomics is an emerging scientific discipline examining the genetic basis for individual variations in response to therapeutics.

METHODS AND RESULTS

Genetic polymorphisms are a major cause of individual differences in drug response. Metabolic phenotyping can be accomplished by administering a probe drug or substrate and measuring the metabolites and clinical outcomes. However, this approach tends to be labor intensive and requires repeated sample collection from the individual being tested. Alternatively, genotyping allows determination of individual DNA sequence differences for a particular trait. Commonly used genotyping methods include gel electrophoresis-based techniques, such as polymerase chain reaction (PCR) coupled with restriction fragment length polymorphism analysis, multiplex PCR, and allele-specific amplification. Fluorescent dye-based high-throughput genotyping procedures are increasing in popularity, including oligonucleotide ligation assay, direct heterozygote sequencing, and TaqMan (Perkin Elmer, Foster City, CA) allelic discrimination. High-density chip array and mass spectrometry technologies are the newest advances in the genotyping field, but their wide application is yet to be developed. Novel mutations/polymorphisms also can be identified by conformation-based mutation screening and direct high-throughput heterozygote sequencing.

CONCLUSIONS

Rapid and accurate detection of genetic polymorphisms has great potential for application to drug development, animal toxicity studies, improvement of human clinical trials, and postmarket monitoring surveillance for drug efficacy and toxicity.

High throughput genotyping for the detection of a single nucleotide polymorphism in NAD(P)H quinone oxidoreductase (DT diaphorase) using TaqMan probes

AIMS

The two electron reduction of quinones to hydroquinones by NAD(P)H quinone oxidoreductase (NQO1) plays an important role in both activation and detoxification of quinone and similarly reactive compounds. A single nucleotide polymorphism at exon 6 leads to an amino acid change at codon 187 from proline to serine. The variant allele has been associated with decreased NQO1 enzyme activity and increased cancer risks. The aim of this study was to develop a rapid genotyping procedure for epidemiological and clinical research into the potential biological and toxicological implications associated with this genetic polymorphism.

METHODS

A high throughput genotyping method using fluorogenic probes has been developed to screen this single nucleotide polymorphism. This assay utilises the 5' nuclease activity of Taq polymerase in conjunction with fluorogenic TaqMan probes. The TaqMan genotyping procedure was validated by a restriction fragment length polymorphism method and direct sequencing.

RESULTS

This method can be used for the rapid screening of known polymorphisms in large populations. In a population of 143 unrelated individuals, Pro/Pro (wildtype), Pro/Ser (heterozygous), and Ser/Ser (mutant) genotypes were 69.2%, 26.6%, and 4.2%, respectively.

CONCLUSIONS

This genotyping method is highly accurate and could be applied to automated large scale genotyping studies.

Molecular cloning and characterization of a novel human CC chemokine, SCYA26

By searching the Expressed Sequence Tag database, a full-length cDNA for a novel human CC chemokine was cloned. This cDNA encoded a 94-amino-acid protein with a putative signal peptide of 26 amino acids. The deduced mature protein had the four conserved cysteine residues characteristic of CC chemokines and showed 44% identity with MIP-1beta and 40% identity with MIP-1alpha, RANTES, and MCP-4. mRNA for this chemokine was expressed constitutively in human heart and liver and with lesser but detectable levels in skeletal muscle, kidney, and small intestine. To investigate its biological activity, the protein was expressed in mammalian cells and purified by affinity chromatography. The recombinant protein demonstrated chemotactic activity in vitro for T cells and monocytes but not for neutrophils. The gene was mapped to chromosome 7q11.2 by fluorescence in situ hybridization. Based on its structural identity with other CC chemokines and the chemotactic activity and chromosomal location of this chemokine, we designate this chemokine small inducible cytokine subfamily A, member 26 (SCYA26). This gene symbol has been approved by the HUGO Gene Nomenclature Committee.

Regulation of macrophage inflammatory protein-2 gene expression by oxidative stress in rat alveolar macrophages

Chemokines are important mediators in the development of inflammation. Our previous work demonstrated that an oxidative stress can up-regulate mRNA expression of a CC chemokine macrophage inflammatory protein (MIP)-1alpha in rat alveolar macrophages. In the present study, we further investigate whether an oxidative stress can regulate the gene expression of a related CXC chemokine MIP-2, involved in both neutrophil chemotaxis and activation. A rat alveolar macrophage cell line (NR8383) was exposed to 10 microg/ml bacterial lipopolysaccharide (LPS) and MIP-2 mRNA levels dramatically increased after 4 hr of stimulation. This increase by LPS was attenuated by co-treatment with the antioxidants N-acetylcysteine and dimethylsulphoxide, suggesting that the induction of MIP-2 mRNA is mediated via the generation of reactive oxygen species. To assess directly the role of oxidative stress on regulation of MIP-2 mRNA expression, macrophages were exposed to H2O2. MIP-2 mRNA levels had significantly increased after 1 hr exposure to 0.5 mm H2O2, were maximally increased after 4 hr and decreased after 6 hr. Co-treatment of macrophages with the transcriptional inhibitor actinomycin D eliminated the H2O2-induction of MIP-2 mRNA, implicating a role for transcriptional activation in increased expression of MIP-2. Genomic cloning of the rat MIP-2 gene 5'-flanking region has identified a consensus nuclear factor-kappaB (NF-kappaB) binding site. Gel-mobility shift assays revealed NF-kappaB binding to the MIP-2 promoter/enhancer sequence was induced by H2O2. LPS treatment for 4 hr also significantly activated NF-kappaB binding, which could also be attenuated by pretreatment with N-acetylcysteine at the doses that reduced MIP-2 mRNA expression. The half-life of MIP-2 mRNA transcripts was also increased by H2O2 treatment. These observations indicate that MIP-2 gene expression is subject to both transcriptional and post-transcriptional control in response to an H2O2 oxidative stress.

High-throughput genotyping method for glutathione S-transferase T1 and M1 gene deletions using TaqMan probes

A high-throughput genotyping method has been developed to detect gene deletion polymorphisms of glutathione-S-transferase theta and mu (GSTT1 and GSTM1). This method utilizes the 5'-nuclease activity of Taq polymerase in conjunction with fluorogenic TaqMan probes. In contrast to traditional allelic discrimination genotyping to detect single nucleotide polymorphisms, the current assay has been designed to detect gene deletion by utilizing custom-designed TaqMan probes in conjunction with an exogenous internal positive control probe. The TaqMan genotyping results were validated by a commonly used multiplex PCR technique. Screening of 71 unrelated individuals revealed gene deletion (null) genotype of 15.5% and 40.8% for GSTT1 and GSTM1, respectively. This TaqMan genotyping method is rapid, reproducible, and highly sensitive and could be applied toward fully automated large-scale genotyping.

Quinones increase gamma-glutamyl transpeptidase expression by multiple mechanisms in rat lung epithelial cells

gamma-Glutamyl transpeptidase (GGT) plays an important role in glutathione (GSH) metabolism. GGT expression is increased in oxidant-challenged cells; however, the signaling mechanisms involved are uncertain. The present study used 2,3-dimethoxy-1,4-naphthoquinone (DMNQ), a redox cycling quinone that continuously produced H2O2 in rat lung epithelial L2 cells. It was found that DMNQ increased GGT mRNA content by increasing transcription, as measured by nuclear run-on. This was accompanied by increased GGT specific activity. Cycloheximide, a protein synthesis inhibitor, blocked neither the increased GGT mRNA content nor the increased GGT transcription rate caused by DMNQ, suggesting that increased GGT transcription was a direct rather than secondary response. Previous data from this laboratory (R.-M. Liu, H. Hu, T. W. Robinson, and H. J. Forman. Am. J. Respir. Cell Mol. Biol. 14: 186-191, 1996) showed that tert-butylhydroquinone (TBHQ) increased GGT mRNA content by increasing its stability. TBHQ differs markedly from DMNQ in terms of its conjugation with GSH and H2O2 generation. Together, the data suggest that quinones upregulate GGT through multiple mechanisms, increased transcription and posttranscriptional modulation, which are apparently mediated through generation of reactive oxygen species and GSH conjugated formation, respectively.

Functional characterization of recombinant rat macrophage inflammatory protein-1 alpha and mRNA expression in pulmonary inflammation

Chemokines are important inflammatory mediators that function by activating and recruiting leukocytes to an inflamed tissue. We have recently cDNA cloned the rat chemokine macrophage inflammatory protein-1 alpha (MIP-1 alpha) (1). In the present study, we characterize the biological function of recombinant MIP-1 alpha protein and describe expression of its mRNA both in vitro and in a rat model of lung inflammation. In vitro rat rMIP-1 alpha protein was chemotactic for both polymorphonuclear leukocytes (PMNs) and macrophages with maximal activity at 50 nM for both cell types. In in vivo studies, we found that intratracheal instillation of 1 and 5 micrograms of rMIP-1 alpha resulted in a significant (P < 0.05) influx of cells, primarily monocytes/macrophages, into the airspace of the lungs after 6 h. Mean numbers of lavagable PMNs were not elevated significantly (P < 0.05) for either dose of MIP-1 alpha. As a model of inflammation, rats were intratracheally instilled with 0.1 mg/kg bacterial lipopolysaccharide (LPS). Bronchoalveolar lavage (BAL) was performed 3 h later. Instillation of LPS resulted in an acute neutrophilia, but no significant change in lavagable macrophages. BAL cells from control animals (saline instilled) displayed no basal mRNA expression of either MIP-1 alpha or MIP-2 (positive control). In contrast, both MIP-1 alpha and MIP-2 mRNA levels increased markedly in BAL cells from rats instilled with LPS. The rat alveolar macrophage cell line (NR8383) also showed increased MIP-1 alpha mRNA levels in response to LPS (10 micrograms/ml) with a maximal increase after 6-8 h. The induction of MIP-1 alpha mRNA expression by LPS in NR8383 cells was attenuated by cotreatment with the antioxidants N-acetylcysteine and dimethylsulfoxide, suggesting that the induction of MIP-1 alpha mRNA by LPS is mediated via the generation of reactive oxygen species. We conclude that MIP-1 alpha is a potent chemoattractant for macrophages in vivo, and its mRNA expression in macrophages and BAL cells in response to inflammatory stimuli suggests a fundamental role in acute pulmonary inflammation.

Increased transcription of the regulatory subunit of gamma-glutamylcysteine synthetase in rat lung epithelial L2 cells exposed to oxidative stress or glutathione depletion

gamma-Glutamylcysteine synthetase (GCS) is the initial and rate-limiting enzyme in the glutathione (GSH) de novo synthesis pathway. GCS is composed of a heavy (73-kDa) catalytic subunit and a light (30-kDa) regulatory subunit, which maintains the Km for glutamate near physiologic concentrations. Previous studies have shown that the steady-state mRNA level and gene transcription for the catalytic subunit increased in response to the redox-cycling quinone 2,3-dimethoxy-1,4-naphthoquinone (DMNQ) in rat lung epithelial L2 cells (M. M. Shi, et al., 1994, J. Biol. Chem. 269,26512-26517). The ratio of the catalytic to regulatory subunit mRNAs varies among tissues, and the anticancer drug cisplatin appears to induce only the catalytic subunit, suggesting independent gene regulation of the two subunits. Nonetheless, the present study found that the steady-state mRNA level and the transcription rate of the GCS regulatory subunit also increased under DMNQ-induced oxidative stress. Changes in mRNA followed a pattern similar to that for the catalytic subunit. The mRNA levels of the two subunits of GCS also both increased above the baseline levels in cells treated with BSO, an inhibitor of GCS enzymatic activity. These data suggest that, under conditions of oxidative stress or glutathione depletion, the regulatory subunit is upregulated at the level of mRNA transcription. Along with the elevation of the catalytic subunit, this increase in GCS regulatory subunit transcription contributes to increases in GCS enzymatic activity and cellular GSH content.

Regulation of macrophage inflammatory protein-1alpha mRNA by oxidative stress

Accumulation of inflammatory cells within the lung has been implicated in oxidative injury. Recruitment of these cells to a tissue site is a complex process that depends in part upon the local expression of appropriate proinflammatory chemokines. Macrophage inflammatory protein-1alpha (MIP-1alpha), a member of the CC subfamily of chemokines, has been shown to contribute to monocyte/macrophage and neutrophil chemotaxis and activation. Our previous work demonstrated that MIP-1alpha mRNA expression in macrophages is induced by bacterial endotoxin. The objective of this study was to test the hypothesis that an oxidative stress alone may trigger expression of MIP-1alpha mRNA in macrophages and to determine the mechanism leading to increased expression. A rat alveolar macrophage cell line (NR8383) was exposed to H2O2 or menadione (2-methyl-1,4-naphthoquinone (MQ)), a quinone compound that undergoes redox cycling and generates reactive oxygen species continuously. Steady-state mRNA levels encoding MIP-1alpha were markedly increased (3-fold) in these cells after 1 h of exposure to 0.5 mM H2O2, remained higher than control levels after 4 h, and decreased after 6 h. Similarly, MQ (25 or 50 microM) caused a significant increase of MIP-1 alpha mRNA with a maximal induction after 4 h of exposure (5-fold). Both H2O2 and MQ-induced up-regulation of MIP-1 alpha mRNA was suppressed by co-treatment with N-acetylcysteine, a synthetic antioxidant. Co-treatment with actinomycin D reduced the MQ induction of MIP-1alpha mRNA to a greater extent than the H2O2-induced increase. Transcription of the MIP-1alpha gene was increased by exposure to both H2O2 and MQ. H2O2 treatment also induced a marked increase of the MIP-1alpha mRNA half-life, indicating post-transcriptional stabilization. These observations indicate that an oxidative stress can regulate MIP-1alpha mRNA expression by two distinct mechanisms: transcriptional activation of the MIP-1alpha gene and post-transcriptional stabilization of MIP-1alpha mRNA.

Molecular cloning and posttranscriptional regulation of macrophage inflammatory protein-1 alpha in alveolar macrophages

Macrophage inflammatory protein-1 alpha (MIP-1 alpha) belongs to the "chemokine" superfamily of chemoattractant pro-inflammatory cytokines. MIP-1 alpha is chemotactic for monocytes and neutrophils and thus, plays an important role in initiation and control of inflammation. We have isolated and sequenced a cDNA clone encoding rat MIP-1 alpha. This 0.75 kb cDNA includes a single open reading frame of 92 amino acids. Expression of MIP-1 alpha mRNA was characterized in NR8383, a rat alveolar macrophage cell line (RAM). In resting RAM cells, MIP-1 alpha mRNA decayed rapidly, with a half life of less than 2 hours. Lipopolysaccharide (LPS) treatment of RAM cells resulted in a dose-dependent increase in MIP-1 alpha steady state mRNA expression. The induction of MIP-1 alpha mRNA by LPS was partially the result of mRNA stabilization, as half life increased to over 6 hours.

gamma-Glutamyl transpeptidase is increased by oxidative stress in rat alveolar L2 epithelial cells

The tripeptide glutathione (GSH) is used by cells to detoxify hydroperoxides, produced during oxidative stress, and is consumed in the process. Previous studies have indicated that cells can be protected against oxidative stress by extracellular GSH through its degradation catalyzed by the exoenzyme gamma-glutamyl transpeptidase (gamma GT) and its de novo synthesis within the cytosol. We hypothesized that gamma GT would be increased as part of the adaptation of cells to oxidative stress. We examined whether oxidative stress could increase gamma GT activity, protein, and mRNA in a lung epithelial cell line (L2). Cultures were subjected to H2O2-mediated toxicity by 15 min of exposure to the redox cycling quinone, menadione. Menadione (50 microM) caused an initial decrease (27 +/- 9% of baseline after 15 min) in intracellular GSH, followed by resynthesis to levels significantly higher than baseline (335 +/- 40% after 24 h, P < 0.001). This elevation was prevented by acivicin, a gamma GT inhibitor. Menadione also caused a dose-dependent increase in gamma GT enzymatic activity (715 +/- 125% of control at 24 h after 15 min of exposure to 100 microM menadione, P < 0.001) that was prevented by actinomycin D. Western blot analysis indicated increased levels of gamma GT protein with increasing menadione. A concentration-dependent increase in gamma GT-mRNA was also observed. Previous investigation has demonstrated that an increase in gamma GT activity enhances the capacity of cells to utilize extracellular GSH. The findings presented here are consistent with a role for gamma GT in cellular adaptation to oxidative stress.

Quinone-induced oxidative stress elevates glutathione and induces gamma-glutamylcysteine synthetase activity in rat lung epithelial L2 cells

Glutathione (GSH) is one of the most important physiological antioxidants involved in detoxification of hydrogen peroxide and lipid hydroperoxide. Previous studies have shown that cells can maintain and even increase cellular GSH content in response to sublethal oxidative stress. We hypothesized that gamma-glutamylcysteine synthetase (gamma GCS), the rate-limiting enzyme in de novo GSH synthesis, could be induced by oxidative stress. Rat lung epithelial L2 cells were challenged with 2,3-dimethoxy-1,4-naphthoquinone (DMNQ), generates O2.- and H2O2 continuously through redox cycling. Exposure of confluent L2 cells with sublethal doses of DMNQ caused sustained elevation of cellular GSH levels over a 24-h period (to 2.5-fold with 10 microM). DMNQ caused increases in gamma GCS activity (70% at 24 h with 10 microM), the gamma GCS catalytic heavy subunit (gamma GCS-HS) protein level, and gamma GCS-HS mRNA content (approximately 4-fold after 6 h with 10 microM). The elevation of gamma GCS-HS mRNA by DMNQ was eliminated by co-incubation with actinomycin D. Nuclear run-on experiments demonstrated that the transcriptional rate of the gamma GCS-HS gene was increased by 3- or 6-h exposure to 10 microM DMNQ. Our results suggested that the induction of de novo GSH synthesis by naphthoquinone-induced oxidative stress is associated with the transcriptional activation of the gamma GCS-HS gene and the subsequent elevation in gamma GCS activity. Unlike simpler quinones, DMNQ cannot form a GSH conjugate. Thus, the induction of gamma GCS-HS gene transcription does not require formation of an electrophile-glutathione conjugate.

gamma-Glutamylcysteine synthetase and GSH increase in quinone-induced oxidative stress in BPAEC

Glutathione (GSH), an important physiological antioxidant, is synthesized de novo by the sequential reactions of gamma-glutamylcysteine synthetase (gamma GCS) and GSH synthetase. In the present studies, incubation with the quinones 2,3-dimethoxy-1,4-naphthoquinone (DMNQ) and menadione (MQ), which generate superoxide and hydrogen peroxide, was used to investigate GSH synthesis in bovine pulmonary artery endothelial cells under oxidative stress. MQ can also cause initial depletion of GSH through conjugation, whereas DMNQ cannot. during continuous exposure to DMNQ (5 or 10 microM), elevation of GSH by DMNQ started after 6 h, almost doubled after 24 h, and remained at this level to 48 h. The elevation of GSH by DMNQ was mostly in the reduced form, and the ratio of reduced to oxidized glutathione remained unchanged for the first 24 h. Treatment with MQ (25 or 50 microM) for 30 min caused a significant decrease in GSH and total glutathione. After changing the medium to remove any residual MQ, GSH content doubled during the next 12 h. The enzymatic activity of gamma GCS, the rate-limiting enzyme of GSH biosynthesis, increased twofold after 12 h of exposure of cells to either 5 microM DMNQ or 50 microM MQ. Both DMNQ and MQ treatment caused concentration- and time-dependent increases in gamma GCS-mRNA expression. The elevation of gamma GCS-mRNA content by DMNQ for 12 h was completely blocked by coincubation with 0.05 microgram/ml actinomycin D but not 0.5 microgram/ml cycloheximide, suggesting the elevation of gamma GCS-mRNA content occurred through increased transcription. Our results suggest that increased de novo GSH synthesis, mediated by an elevation in gamma GCS, constitutes an adaptive response to oxidative stress.

Enzymic cleavage as a probe of the molecular structures of mammalian equilibrative nucleoside transporters

We have used enzymic cleavage by trypsin in conjunction with glycosidase digestion to probe the transmembrane topologies and molecular structures of mammalian equilibrative, nitrobenzylthioinosine (NBMPR)-sensitive, nucleoside transport systems. Transporters from four species (human, pig, guinea pig, and rat) and three tissues (erythrocyte, liver, and lung), which differ from each other in size and in their sensitivity to inhibition by the vasodilator dipyridamole, were investigated. Broadly equivalent sites of [3H]NBMPR photolabeling, carbohydrate attachment, and trypsin cleavage were observed for all systems. Results from these experiments demonstrate that molecular weight differences between rat transporters and those from two other species (human and guinea pig) are due largely to oligosaccharide heterogeneity and that the low dipyridamole sensitivity of rat nucleoside transporters is probably a consequence of relatively minor differences in molecular structure. In marked contrast, carbohydrate removal increases the molecular weight difference between the pig erythrocyte transporter and, for example, that in human erythrocytes. This polypeptide difference is limited largely, if not completely, to one tryptic fragment of the protein. In the case of the human erythrocyte transporter, the site of N-linked glycosylation has been located very close to one end of the protein, and the site of NBMPR photolabeling to within 16 kDa of that site. Trypsin cleavage occurs endofacially. Our results provide evidence of substantial structural conservation among mammalian NBMPR-sensitive nucleoside transporters.

Inhibition of radioligand binding to A1 adenosine receptors by Bay K8644 and nifedipine

Two dihydropyridine compounds, Bay K8644 (a calcium entry activator) and nifedipine (a calcium entry blocker), were found to inhibit the binding of [3H]phenylisopropyladenosine ([3H]PIA) to A1 adenosine receptors in rat cerebral cortex membranes with comparable potencies (IC50 10-30 microM). Scatchard analyses indicated that both Bay K8644 and nifedipine inhibited the binding of [3H]PIA by increasing the KD but without significant effect on the Bmax. When tested at 100 microM, neither Bay K8644 nor nifedipine showed a significant effect on [3H]-p-aminoclonidine ([3H]PAC; alpha 2-adrenergic receptor), [3H]dihydroalprenolol ([3H]DHA; beta-adrenergic receptor), [3H]spiperone (dopamine receptor), and [3H]nitrobenzylthioinosine [( 3H]NBMPR; nucleoside transporter) binding. In the presence of 10 mM Mg2+, the ability of 2-chloroadenosine (2-Cl-Ad, an A1 adenosine receptor agonist) to displace [3H]PIA binding was increased. Conversely, the potencies of 1,3-diethyl-8-phenylxanthine (DPX; an A1 receptor antagonist), Bay K8644 and nifedipine in inhibiting [3H]PIA binding were unchanged. It is suggested that both Bay K8644 and nifedipine may act as antagonists of adenosine A1 receptors, in addition to their well-known effects on calcium channels.

[3H]dipyridamole binding to nucleoside transporters from guinea-pig and rat lung

Membranes from guinea-pig lung exhibited high-affinity binding of [3H]dipyridamole, a potent inhibitor of nucleoside transport. Binding (apparent KD 2 nM) was inhibited by the nucleoside-transport inhibitors nitrobenzylthioinosine (NBMPR), dilazep and lidoflazine and by the transported nucleosides uridine and adenosine. In contrast, there was no detectable high-affinity binding of [3H]dipyridamole to lung membranes from the rat, a species whose nucleoside transporters exhibit a low sensitivity to dipyridamole inhibition. Bmax. values for high-affinity binding of [3H]dipyridamole and [3H]NBMPR to guinea-pig membranes were similar, suggesting that these structurally unrelated ligands bind to the NBMPR-sensitive nucleoside transporter with the same stoichiometry.

Nucleoside transport. Photoaffinity labelling of high-affinity nitrobenzylthioinosine binding sites in rat and guinea pig lung

Binding of the potent nucleoside transport inhibitor [3H]nitrobenzylthioinosine to rat and guinea pig lung membranes was investigated. Reversible high-affinity binding was found in both species (apparent KD approximately 0.3nM). Binding was inhibited by nitrobenzylthioguanosine, adenosine and uridine. Dipyridamole was also an effective inhibitor of [3H]nitrobenzylthioinosine binding to guinea pig membranes. In contrast, rat membranes were relatively insensitive to dipyridamole. Exposure of site-bound [3H]nitrobenzylthioinosine to high intensity U.V. light resulted in the photoaffinity labelling of lung proteins with apparent molecular weights similar to that of the human erythrocyte nucleoside transporter (45,000-65,000).

Activation of ouabain-sensitive p-nitrophenylphosphatase by carbachol and cGMP in rat submandibular gland

Na+,K+-ATPase activity was monitored by measuring ouabain-sensitive K+-dependent p-nitrophenylphosphatase (p-NPPase) activity in rat submandibular gland slices. Carbachol (carbamylcholine chloride) stimulated the p-NPPase activity in the presence of calcium but not in its absence. Carbachol activation of the enzyme was totally ouabain sensitive and could be blocked by atropine. A minimal requirement of sodium ion extracellularly was required for this carbachol stimulation. cGMP and its dibutyryl analogue was also effective in stimulating the enzyme activity, whereas, cAMP was ineffective. Calcium, however, was not required for cGMP activation of the p-NPPase activity. The result indicates that calcium is the second messenger and cGMP is the tertiary connection between cholinergic stimulation and Na+,K+-ATPase activation in these glands. Activation of Na+,K+-ATPase is postulated to be responsible for primary fluid formation.