Determinants of exposure to endocrine disruptors following hurricane Harvey

Hurricane Harvey was a category four storm that induced catastrophic flooding in the Houston metropolitan area. Following the hurricane there was increased concern regarding chemical exposures due to damage caused by flood waters and emergency excess emissions from industrial facilities. This study utilized personal passive samplers in the form of silicone wristbands in Houston, TX to both assess chemical exposure to endocrine disrupting chemicals (EDCs) immediately after the hurricane and determine participant characteristics associated with higher concentrations of exposure. Participants from the Houston-3H cohort (n = 172) wore a wristband for seven days and completed a questionnaire to determine various flood-related and demographic variables. Bivariate and multivariate analysis indicated that living in an area with a high Area Deprivation Index (ADI) (indicative of low socioeconomic status), identifying as Black/African American or Latino, and living in the Houston neighborhoods of Baytown and East Houston were associated with increased exposure to EDCs. These results provide evidence of racial/ethnic and socioeconomic injustices in exposure to EDCs in the Houston Metropolitan Area. Since the multiple regression models conducted did not fully explain exposure (0.047 < R2 < 0.34), more research is needed on the direct sources of EDCs within this area to create effective exposure mitigation strategies.

Statin therapy inhibits fatty acid synthase via dynamic protein modifications

Statins are a class of drug widely prescribed for the prevention of cardiovascular disease, with pleiotropic cellular effects. Statins inhibit HMG-CoA reductase (HMGCR), which converts the metabolite HMG-CoA into mevalonate. Recent discoveries have shown HMG-CoA is a reactive metabolite that can non-enzymatically modify proteins and impact their activity. Therefore, we predicted that inhibition of HMGCR by statins might increase HMG-CoA levels and protein modifications. Upon statin treatment, we observe a strong increase in HMG-CoA levels and modification of only a single protein. Mass spectrometry identifies this protein as fatty acid synthase (FAS), which is modified on active site residues and, importantly, on non-lysine side-chains. The dynamic modifications occur only on a sub-pool of FAS that is located near HMGCR and alters cellular signaling around the ER and Golgi. These results uncover communication between cholesterol and lipid biosynthesis by the substrate of one pathway inhibiting another in a rapid and reversible manner.

Deglutarylation of glutaryl-CoA dehydrogenase by deacylating enzyme SIRT5 promotes lysine oxidation in mice

A wide range of protein acyl modifications has been identified on enzymes across various metabolic processes; however, the impact of these modifications remains poorly understood. Protein glutarylation is a recently identified modification that can be nonenzymatically driven by glutaryl-CoA. In mammalian systems, this unique metabolite is only produced in the lysine and tryptophan oxidative pathways. To better understand the biology of protein glutarylation, we studied the relationship between enzymes within the lysine/tryptophan catabolic pathways, protein glutarylation, and regulation by the deglutarylating enzyme sirtuin 5 (SIRT5). Here, we identify glutarylation on the lysine oxidation pathway enzyme glutaryl-CoA dehydrogenase (GCDH) and show increased GCDH glutarylation when glutaryl-CoA production is stimulated by lysine catabolism. Our data reveal that glutarylation of GCDH impacts its function, ultimately decreasing lysine oxidation. We also demonstrate the ability of SIRT5 to deglutarylate GCDH, restoring its enzymatic activity. Finally, metabolomic and bioinformatic analyses indicate an expanded role for SIRT5 in regulating amino acid metabolism. Together, these data support a feedback loop model within the lysine/tryptophan oxidation pathway in which glutaryl-CoA is produced, in turn inhibiting GCDH function via glutaryl modification of GCDH lysine residues and can be relieved by SIRT5 deacylation activity.

Effects of stocking density on large white, commercial tom turkeys reared to 20 weeks of age: 1. growth and performance

Industry standards for turkey stocking densities are variable and may not represent the more rapidly growing strains currently available. Therefore, a study was completed to evaluate 4 stocking densities: a nominal density (0.3525 m²/bird), 10% tighter density (0.3169 m²/bird), 10% looser density (0.3882 m²/bird), and 20% looser density (0.4238 m²/bird) on the effects on large white, commercial male turkeys with regard to performance from 5 to 20 wk of age. Brooding stocking density was fixed for all pens of birds with 60 birds per replicate pen at 0.46 m²/bird to 5 wk of age. Density treatments were applied from 5 to 20 wk by altering pen size with pen population held constant at 60 per pen. There were 4 pens of birds per density treatment. Birds were weighed individually at 0, 5, and 20 wk of age and performance parameters were calculated. There were no differences in bird performance at 5 wk, which was expected because stocking density was fixed. From 5 to 20 wk and at 20 wk, birds that were reared at the nominal standard (0.3525 m²/bird) and 10% tighter density (0.3169 m²/bird) had significantly lower body weight compared with the 10% looser density (0.3882 m²/bird) and 20% looser density (0.4238 m²/bird) (P = 0.03 and 0.01, respectfully). The feed conversion ratio (FCR) tended (P = 0.08) to be improved for birds reared at looser density. In addition, based on linear regression, as stocking density decreased (i.e., m²/bird increased), BW (P < 0.05) increased, and FCR (P = 0.10) tended to decrease (improve) at 20 wk. It was concluded that birds reared at looser density had improved performance.

β-Cell-specific ablation of sirtuin 4 does not affect nutrient-stimulated insulin secretion in mice

Sirtuins are a family of proteins that regulate biological processes such as cellular stress and aging by removing posttranslational modifications (PTMs). We recently identified several novel PTMs that can be removed by sirtuin 4 (SIRT4), which is found in mitochondria. We showed that mice with a global loss of SIRT4 [SIRT4-knockout (KO) mice] developed an increase in glucose- and leucine-stimulated insulin secretion, and this was followed by accelerated age-induced glucose intolerance and insulin resistance. Because whole body SIRT4-KO mice had alterations to nutrient-stimulated insulin secretion, we hypothesized that SIRT4 plays a direct role in regulating pancreatic β-cell function. Thus, we tested whether β-cell-specific ablation of SIRT4 would recapitulate the elevated insulin secretion seen in mice with a global loss of SIRT4. Tamoxifen-inducible β-cell-specific SIRT4-KO mice were generated, and their glucose tolerance and glucose- and leucine-stimulated insulin secretion were measured over time. These mice exhibited normal glucose- and leucine-stimulated insulin secretion and maintained normal glucose tolerance even as they aged. Furthermore, 832/13 β-cells with a CRISPR/Cas9n-mediated loss of SIRT4 did not show any alterations in nutrient-stimulated insulin secretion. Despite the fact that whole body SIRT4-KO mice demonstrated an age-induced increase in glucose- and leucine-stimulated insulin secretion, our current data indicate that the loss of SIRT4 specifically in pancreatic β-cells, both in vivo and in vitro, does not have a significant impact on nutrient-stimulated insulin secretion. These data suggest that SIRT4 controls nutrient-stimulated insulin secretion during aging by acting on tissues external to the β-cell, which warrants further study.

Metabolic control by sirtuins and other enzymes that sense NAD+, NADH, or their ratio

NAD⁺ is a dinucleotide cofactor with the potential to accept electrons in a variety of cellular reduction-oxidation (redox) reactions. In its reduced form, NADH is a ubiquitous cellular electron donor. NAD⁺, NADH, and the NAD⁺/NADH ratio have long been known to control the activity of several oxidoreductase enzymes. More recently, enzymes outside those participating directly in redox control have been identified that sense these dinucleotides, including the sirtuin family of NAD⁺-dependent protein deacylases. In this review, we highlight examples of non-redox enzymes that are controlled by NAD⁺, NADH, or NAD⁺/NADH. In particular, we focus on the sirtuin family and assess the current evidence that the sirtuin enzymes sense these dinucleotides and discuss the biological conditions under which this might occur; we conclude that sirtuins sense NAD⁺, but neither NADH nor the ratio. Finally, we identify future studies that might be informative to further interrogate physiological and pathophysiological changes in NAD⁺ and NADH, as well as enzymes like sirtuins that sense and respond to redox changes in the cell.

SIRT4 Is a Lysine Deacylase that Controls Leucine Metabolism and Insulin Secretion

Sirtuins are NAD⁺-dependent protein deacylases that regulate several aspects of metabolism and aging. In contrast to the other mammalian sirtuins, the primary enzymatic activity of mitochondrial sirtuin 4 (SIRT4) and its overall role in metabolic control have remained enigmatic. Using a combination of phylogenetics, structural biology, and enzymology, we show that SIRT4 removes three acyl moieties from lysine residues: methylglutaryl (MG)-, hydroxymethylglutaryl (HMG)-, and 3-methylglutaconyl (MGc)-lysine. The metabolites leading to these post-translational modifications are intermediates in leucine oxidation, and we show a primary role for SIRT4 in controlling this pathway in mice. Furthermore, we find that dysregulated leucine metabolism in SIRT4KO mice leads to elevated basal and stimulated insulin secretion, which progressively develops into glucose intolerance and insulin resistance. These findings identify a robust enzymatic activity for SIRT4, uncover a mechanism controlling branched-chain amino acid flux, and position SIRT4 as a crucial player maintaining insulin secretion and glucose homeostasis during aging.

Detection of the Previously Unobserved Stereoisomers of Thujone in the Essential Oil and Consumable Products of Sage (Salvia officinalis L.) Using Headspace Solid-Phase Microextraction-Gas Chromatography-Mass Spectrometry

The discovery of the (+)-α-thujone and (-)-β-thujone stereoisomers in the essential oil of sage (Salvia officinalis L.) and dietary supplements is documented for the first time. The detection was accomplished using a chiral resolution protocol of racemic α-/β-thujone on headspace solid-phase microextraction-gas chromatography-mass spectrometry. Because the previously unreported stereoisomers, (+)-α-thujone and (-)-β-thujone, are not commercially available, a three-step synthesis of racemic thujone from commercially available starting materials was developed. Thermolysis studies demonstrated that no racemization at the cyclopropane stereocenters occurs, corroborating that the detection is not an artifact from the hydrodistillation process. The developed chiral resolution of thujone was also used to provide evidence for the absence of the (+)-α-thujone and (-)-β-thujone enantiomers in other common thujone-containing essential oils.

Investigating the Sensitivity of NAD+-dependent Sirtuin Deacylation Activities to NADH

Protein lysine posttranslational modification by an increasing number of different acyl groups is becoming appreciated as a regulatory mechanism in cellular biology. Sirtuins are class III histone deacylases that use NAD(+)as a co-substrate during amide bond hydrolysis. Several studies have described the sirtuins as sensors of the NAD(+)/NADH ratio, but it has not been formally tested for all the mammalian sirtuinsin vitro To address this problem, we first synthesized a wide variety of peptide-based probes, which were used to identify the range of hydrolytic activities of human sirtuins. These probes included aliphatic ϵ-N-acyllysine modifications with hydrocarbon lengths ranging from formyl (C1) to palmitoyl (C16) as well as negatively charged dicarboxyl-derived modifications. In addition to the well established activities of the sirtuins, "long chain" acyllysine modifications were also shown to be prone to hydrolytic cleavage by SIRT1-3 and SIRT6, supporting recent findings. We then tested the ability of NADH, ADP-ribose, and nicotinamide to inhibit these NAD(+)-dependent deacylase activities of the sirtuins. In the commonly used 7-amino-4-methylcoumarin-coupled fluorescence-based assay, the fluorophore has significant spectral overlap with NADH and therefore cannot be used to measure inhibition by NADH. Therefore, we turned to an HPLC-MS-based assay to directly monitor the conversion of acylated peptides to their deacylated forms. All tested sirtuin deacylase activities showed sensitivity to NADH in this assay. However, the inhibitory concentrations of NADH in these assays are far greater than the predicted concentrations of NADH in cells; therefore, our data indicate that NADH is unlikely to inhibit sirtuinsin vivo These data suggest a re-evaluation of the sirtuins as direct sensors of the NAD(+)/NADH ratio.

SnapShot: Mammalian Sirtuins

The mammalian sirtuins have emerged as critical regulators of cellular stress resistance, energy metabolism, and tumorigenesis. In some contexts, they delay the onset of age-related diseases and promote a healthy lifespan. The seven mammalian sirtuins, SIRT1-7, share a highly conserved NAD+-binding catalytic core domain although they exhibit distinct expression patterns, catalytic activities, and biological functions. This SnapShot provides an overview of these properties, with an emphasis on their relevance to aging.

Lysine glutarylation is a protein posttranslational modification regulated by SIRT5

We report the identification and characterization of a five-carbon protein posttranslational modification (PTM) called lysine glutarylation (Kglu). This protein modification was detected by immunoblot and mass spectrometry (MS), and then comprehensively validated by chemical and biochemical methods. We demonstrated that the previously annotated deacetylase, sirtuin 5 (SIRT5), is a lysine deglutarylase. Proteome-wide analysis identified 683 Kglu sites in 191 proteins and showed that Kglu is highly enriched on metabolic enzymes and mitochondrial proteins. We validated carbamoyl phosphate synthase 1 (CPS1), the rate-limiting enzyme in urea cycle, as a glutarylated protein and demonstrated that CPS1 is targeted by SIRT5 for deglutarylation. We further showed that glutarylation suppresses CPS1 enzymatic activity in cell lines, mice, and a model of glutaric acidemia type I disease, the last of which has elevated glutaric acid and glutaryl-CoA. This study expands the landscape of lysine acyl modifications and increases our understanding of the deacylase SIRT5.

Generating mammalian sirtuin tools for protein-interaction analysis

The sirtuins are a family of NAD(+)-dependent deacylases with important effects on aging, cancer, and metabolism. Sirtuins exert their biological effects by catalyzing deacetylation and/or deacylation reactions in which Acyl groups are removed from lysine residues of specific proteins. A current challenge is to identify specific sirtuin target proteins against the high background of acetylated proteins recently identified by proteomic surveys. New evidence indicates that bona fide sirtuin substrate proteins form stable physical associations with their sirtuin regulator. Therefore, identification of sirtuin interacting proteins could be a useful aid in focusing the search for substrates. Described here is a method for identifying sirtuin protein interactors. Employing basic techniques of molecular cloning and immunochemistry, the method describes the generation of mammalian sirtuin protein expression plasmids and their use to overexpress and immunoprecipitate sirtuins with their interacting partners. Also described is the use of the Database for Annotation, Visualization, and Integrated Discovery for interpreting the sirtuin protein-interaction data obtained.

Deletion of CaMKK2 from the liver lowers blood glucose and improves whole-body glucose tolerance in the mouse

Ca(2+)/calmodulin-dependent protein kinase kinase 2 (CaMKK2) is a member of the Ca(2+)/CaM-dependent protein kinase family that is expressed abundantly in brain. Previous work has revealed that CaMKK2 knockout (CaMKK2 KO) mice eat less due to a central nervous system -signaling defect and are protected from diet-induced obesity, glucose intolerance, and insulin resistance. However, here we show that pair feeding of wild-type mice to match food consumption of CAMKK2 mice slows weight gain but fails to protect from diet-induced glucose intolerance, suggesting that other alterations in CaMKK2 KO mice are responsible for their improved glucose metabolism. CaMKK2 is shown to be expressed in liver and acute, specific reduction of the kinase in the liver of high-fat diet-fed CaMKK2(floxed) mice results in lowered blood glucose and improved glucose tolerance. Primary hepatocytes isolated from CaMKK2 KO mice produce less glucose and have decreased mRNA encoding peroxisome proliferator-activated receptor γ coactivator 1-α and the gluconeogenic enzymes glucose-6-phosphatase and phosphoenolpyruvate carboxykinase, and these mRNA fail to respond specifically to the stimulatory effect of catecholamine in a cell-autonomous manner. The mechanism responsible for suppressed gene induction in CaMKK2 KO hepatocytes may involve diminished phosphorylation of histone deacetylase 5, an event necessary in some contexts for derepression of the peroxisome proliferator-activated receptor γ coactivator 1-α promoter. Hepatocytes from CaMKK2 KO mice also show increased rates of de novo lipogenesis and fat oxidation. The changes in fat metabolism observed correlate with steatotic liver and altered acyl carnitine metabolomic profiles in CaMKK2 KO mice. Collectively, these results are consistent with suppressed catecholamine-induced induction of gluconeogenic gene expression in CaMKK2 KO mice that leads to improved whole-body glucose homeostasis despite the presence of increased hepatic fat content.

Characterization of the CaMKKβ-AMPK signaling complex

The AMP-activated protein kinase (AMPK) is a critical regulator of energy homeostasis, and is a potential target for treatment of metabolic diseases as well as cancer. AMPK can be phosphorylated and activated by the tumor suppressor LKB1 or the Ca(2+)/CaM-dependent protein kinase kinase β (CaMKKβ). We previously identified a physical complex between CaMKKβ and AMPK (Anderson, K. A., Ribar, T. J., Lin, F., Noeldner, P. K., Green, M. F., Muehlbauer, M. J., Witters, L. A., Kemp, B. E., and Means, A. R. (2008) Cell Metabolism 7, 377-388). Here we expand our analysis of the CaMKKβ-AMPK signaling complex and show that whereas CaMKKβ can form a complex with and activate AMPK, CaMKKα cannot. In addition, we show that CaMKKβ and AMPK associate through their kinase domains, and CaMKKβ must be in an active conformation in order to bind AMPK but not to associate with an alternative substrate, Ca(2+)/Calmodulin-dependent protein kinase IV (CaMKIV). Our results demonstrate that CaMKKβ and AMPK form a unique signaling complex. This raises the possibility that the CaMKKβ-AMPK complex can be specifically targeted by small molecule drugs to treat disease.

Organophosphorus pesticide degradation product in vitro metabolic stability and time-course uptake and elimination in rats following oral and intravenous dosing

Levels of urinary dialkylphosphates (DAPs) are currently used as a biomarker of human exposure to organophosphorus insecticides (OPs). It is known that OPs degrade on food commodities to DAPs at levels that approach or exceed those of the parent OP. However, little has been reported on the extent of DAP absorption, distribution, metabolism and excretion. The metabolic stability of O,O-dimethylphosphate (DMP) was assessed using pooled human and rat hepatic microsomes. Time-course samples were collected over 2 h and analyzed by LC-MS/MS. It was found that DMP was not metabolized by rat or pooled human hepatic microsomes. Male Sprague-Dawley rats were administered DMP at 20 mg kg(-1) via oral gavage and i.v. injection. Time-course plasma and urine samples were collected and analyzed by LC-MS/MS. DMP oral bioavailability was found to be 107 ± 39% and the amount of orally administered dose recovered in the urine was 30 ± 9.9% by 48 h. The in vitro metabolic stability, high bioavailability and extent of DMP urinary excretion following oral exposure in a rat model suggests that measurement of DMP as a biomarker of OP exposure may lead to overestimation of human exposure.

Regional-scale assessment of soil salinity in the Red River Valley using multi-year MODIS EVI and NDVI

The ability to inventory and map soil salinity at regional scales remains a significant challenge to scientists concerned with the salinization of agricultural soils throughout the world. Previous attempts to use satellite or aerial imagery to assess soil salinity have found limited success in part because of the inability of methods to isolate the effects of soil salinity on vegetative growth from other factors. This study evaluated the use of Moderate Resolution Imaging Spectroradiometer (MODIS) imagery in conjunction with directed soil sampling to assess and map soil salinity at a regional scale (i.e., 10-10(5) km(2)) in a parsimonious manner. Correlations with three soil salinity ground truth datasets differing in scale were made in Kittson County within the Red River Valley (RRV) of North Dakota and Minnesota, an area where soil salinity assessment is a top priority for the Natural Resource Conservation Service (NRCS). Multi-year MODIS imagery was used to mitigate the influence of temporally dynamic factors such as weather, pests, disease, and management influences. The average of the MODIS enhanced vegetation index (EVI) for a 7-yr period exhibited a strong relationship with soil salinity in all three datasets, and outperformed the normalized difference vegetation index (NDVI). One-third to one-half of the spatial variability in soil salinity could be captured by measuring average MODIS EVI and whether the land qualified for the Conservation Reserve Program (a USDA program that sets aside marginally productive land based on conservation principles). The approach has the practical simplicity to allow broad application in areas where limited resources are available for salinity assessment.

Central control of feeding

The rising rate of obesity in Western countries has led to intensified efforts to understand the molecular mechanisms underlying the central control of appetite and feeding behavior. This report highlights studies published from 2006 to 2008 revealing novel centrally acting anorexigenic hormones, the continued unraveling of complex hypothalamic intracellular signaling pathways that regulate feeding, and insights into leptin resistance.

Field trial and modeling of uptake rates of in situ lipid-free polyethylene membrane passive sampler

Lipid-free polyethylene membrane tubing (LFT) has been further developed in response to a growing need for an inexpensive and simple time-integrative sampling device for dissolved hydrophobic contaminants in water. The LFT sampler is based on the diffusion of dissolved hydrophobic target compounds through the aqueous boundary layer and into the polyethylene membrane, mimicking uptake by organisms. We demonstrate through laboratory and field validation studies that LFT provided the same benefits as many other passive sampling devices, withoutthe potential of analytical interference from lipid impurities. A total of 370 LFTs and semipermeable membrane devices were deployed for 21 days in paired studies at highly urbanized, undeveloped, and two Superfund sites, representing several river conditions. A simple internal surrogate spiking method served as an in situ calibration indicator of the effects of environmental conditions on the uptake rates. A modified extraction method for the LFT increased recoveries while decreasing solvent use and labor compared to other organic extraction procedures. LFT sampling rates were estimated using ratios, in situ calibration and modeling for over 45 target analytes, including PAHs, PCBs, and pesticides.

Regulation of AMP-activated protein kinase by multisite phosphorylation in response to agents that elevate cellular cAMP

The AMP-activated protein kinase (AMPK) and cAMP signaling systems are both key regulators of cellular metabolism. In this study, we show that AMPK activity is attenuated in response to cAMP-elevating agents through modulation of at least two of its alpha subunit phosphorylation sites, viz. alpha-Thr(172) and alpha1-Ser(485)/alpha2-Ser(491), in the clonal beta-cell line INS-1 as well as in mouse embryonic fibroblasts and COS cells. Forskolin, isobutylmethylxanthine, and the glucose-dependent insulinotropic peptide inhibited AMPK activity and reduced phosphorylation of the activation loop alpha-Thr(172) via inhibition of calcium/calmodulin-dependent protein kinase kinase-alpha and -beta, but not LKB1. These agents also enhanced phosphorylation of alpha-Ser(485/491) by the cAMP-dependent protein kinase. AMPK alpha-Ser(485/491) phosphorylation was necessary but not sufficient for inhibition of AMPK activity in response to forskolin/isobutylmethylxanthine. We show that AMPK alpha-Ser(485/491) can be a site for autophosphorylation, which may play a role in limiting AMPK activation in response to energy depletion or other regulators. Thus, our findings not only demonstrate cross-talk between the cAMP/cAMP-dependent protein kinase and AMPK signaling modules, but also describe a novel mechanism by which multisite phosphorylation of AMPK contributes to regulation of its enzyme activity.

Temporal bioavailability of organochlorine pesticides and PCBs

Because PCBs and organochlorine pesticides continue to be of global concern, studies that address information gaps, such as factors and influences of spatial and temporal effects on contaminant bioavailability, are valuable. The present study focused on the spatial and temporal distribution of bioavailable organochlorine pesticides and PCBs in surface waters of a contaminated harbor. Passive sampling devices were intensively deployed adjacent to various land uses on the Willamette River, OR, including Portland Harbor and McCormick and Baxter Superfund sites, during summer and fall, extreme conditions, 2001-2004. An increase of bioavailable sigmaDDTs (sum of p,p'-DDT, p,p'-DDD, and p,p'-DDE) concentrations was strongly affected bythe local historic production of DDTs and temporal changes in river conditions. The increase of bioavailable p,p'-DDD and high DDD/DDE ratios observed during summer indicates conditions favoring anaerobic reductive processes. In contrast to sigmaDDTs, the bioavailable concentrations and daily loads of dieldrin and PCBs increased during fall, especially during episodic rainstorms. On the basis of the PCB congener profiles, PCB inputs from urban runoff /sewer overflows were considered likely current sources of bioavailable PCB into the Harbor. The exceedence of the U.S. national and Oregon water quality criteria was a function of the temporal variability of each bioavailable contaminant. This illustrates the impacts associated with temporal changes of bioavailable organochlorine distributions in surface waters and the significance of considering realistic temporal, bioavailability, and site-specific conditions in risk assessment and water quality management.

The Ca2+/calmodulin-dependent protein kinase kinases are AMP-activated protein kinase kinases

The AMP-activated protein kinase (AMPK) is an important regulator of cellular metabolism in response to metabolic stress and to other regulatory signals. AMPK activity is absolutely dependent upon phosphorylation of AMPKalphaThr-172 in its activation loop by one or more AMPK kinases (AMPKKs). The tumor suppressor kinase, LKB1, is a major AMPKK present in a variety of tissues and cells, but several lines of evidence point to the existence of other AMPKKs. We have employed three cell lines deficient in LKB1 to study AMPK regulation and phosphorylation, HeLa, A549, and murine embryo fibroblasts derived from LKB(-/-) mice. In HeLa and A549 cells, mannitol, 2-deoxyglucose, and ionomycin, but not 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR), treatment activates AMPK by alphaThr-172 phosphorylation. These responses, as well as the downstream effects of AMPK on the phosphorylation of acetyl-CoA carboxylase, are largely inhibited by the Ca(2+)/ calmodulin-dependent protein kinase kinase (CaMKK) inhibitor, STO-609. AMPKK activity in HeLa cell lysates measured in vitro is totally inhibited by STO-609 with an IC50 comparable with that of the known CaMKK isoforms, CaMKKalpha and CaMKKbeta. Furthermore, 2-deoxyglucose- and ionomycin-stimulated AMPK activity, alphaThr-172 phosphorylation, and acetyl-CoA carboxylase phosphorylation are substantially reduced in HeLa cells transfected with small interfering RNAs specific for CaMKKalpha and CaMKKbeta. Lastly, the activation of AMPK in response to ionomycin and 2-deoxyglucose is not impaired in LKB1(-/-) murine embryo fibroblasts. These data indicate that the CaMKKs function in intact cells as AMPKKs, predicting wider roles for these kinases in regulating AMPK activity in vivo.

The autonomous activity of calcium/calmodulin-dependent protein kinase IV is required for its role in transcription

Calcium/calmodulin-dependent kinase IV (CaMKIV) is a multifunctional serine/threonine kinase that is positively regulated by two main events. The first is the binding of calcium/calmodulin (Ca(2+)/CaM), which relieves intramolecular autoinhibition of the enzyme and leads to basal kinase activity. The second is activation by the upstream kinase, Ca(2+)/calmodulin-dependent kinase kinase. Phosphorylation of Ca(2+)/CaM-bound CaMKIV on its activation loop threonine (residue Thr(200) in human CaMKIV) by Ca(2+)/calmodulin-dependent kinase kinase leads to increased CaMKIV kinase activity. It has also been repeatedly noted that activation of CaMKIV is accompanied by the generation of Ca(2+)/CaM-independent or autonomous activity, although the significance of this event has been unclear. Here we demonstrate the importance of autonomous activity to CaMKIV biological function. We show that phosphorylation of CaMKIV on Thr(200) leads to the generation of a fully Ca(2+)/CaM-independent enzyme. By analyzing the behavior of wild-type and mutant CaMKIV proteins in biochemical experiments and cellular transcriptional assays, we demonstrate that CaMKIV autonomous activity is necessary and sufficient for CaMKIV-mediated transcription. The ability of wild-type CaMKIV to drive cAMP response element-binding protein-mediated transcription is strictly dependent upon an initiating Ca(2+) stimulus, which leads to kinase activation and development of autonomous activity in cells. Mutant CaMKIV proteins that are incapable of developing autonomous activity within a cellular context fail to drive transcription, whereas certain CaMKIV mutants that possess constitutive autonomous activity drive transcription in the absence of a Ca(2+) stimulus and independent of Ca(2+)/CaM binding or Thr(200) phosphorylation.

Regulation and function of the calcium/calmodulin-dependent protein kinase IV/protein serine/threonine phosphatase 2A signaling complex

Calcium/calmodulin-dependent protein kinase IV (CaMKIV) is a member of the broad substrate specificity class of Ca(2+)/calmodulin (CaM)-dependent protein kinases and functions as a potent stimulator of Ca(2+)-dependent gene expression. Activation of CaMKIV is a transient, tightly regulated event requiring both Ca(2+)/CaM binding and phosphorylation of the kinase on T200 by an upstream CaMK kinase (CaMKK). Previously, CaMKIV was shown to stably associate with protein serine/threonine phosphatase 2A (PP2A), which was proposed to play a role in negatively regulating the kinase. Here we report that the Ca(2+)/CaM binding-autoinhibitory domain of CaMKIV is required for association of the kinase with PP2A and that binding of PP2A and Ca(2+)/CaM appears to be mutually exclusive. We demonstrate that inhibition of the CaMKIV/PP2A association in cells results in enhanced CaMKIV-mediated gene transcription that is independent of Ca(2+)/CaM. The enhanced transcriptional activity correlates with the elevated level of phospho-T200 that accumulates when CaMKIV is prevented from interacting with PP2A. Collectively, these data suggest a molecular basis for the sequential activation and inactivation of CaMKIV. First, in response to an increase in intracellular Ca(2+), CaMKIV binds Ca(2+)/CaM and becomes phosphorylated on T200 by CaMKK. These events result in the generation of autonomous activity required for CaMKIV-mediated transcriptional regulation. The CaMKIV-associated PP2A then dephosphorylates CaMKIV T200, thereby terminating autonomous activity and CaMKIV-mediated gene transcription.

Bioaccumulation profiles of chemical contaminants in fish from the lower Willamette River, Portland Harbor, Oregon

Twenty-five PCBs (polychlorinated biphenyls), 15 organochlorine (OC) pesticides, and mercury were determined in fish from the Willamette River in Oregon, including a Portland Harbor superfund site. Fish were collected during the summer of 2000 along a 20-mile stretch of the lower Willamette River. Concentrations of sumPCBs (sum of 25 individually determined PCB congeners) and sumDDTs (sum of p,p'-DDT, p,p'-DDE, and p,p'-DDD) in fish ranged from 14 to 530 and from 18 to 510 ng/g-wet weight, respectively. SumPCBs concentrations at all sites exceeded US EPA fish advisory's screening values. Hexachlorobiphenyl congener 153 was the most abundant of the PCBs detected and p,p'-DDE was the most abundant OC pesticide detected. Low levels of dieldrin were detected in fish at all sites with the highest concentration at the superfund site (4.6 ng/g-wet weight), while other OC pesticides tested were near or below detection limits (approximately 2 ng/g). In general, organic chemical contaminant concentrations were highest in fish from the superfund site and were lower further upriver. Smallmouth bass had the highest levels of OC compounds of three fish species examined. They also had the largest site-to-site variations whereas black crappie had little variation throughout the study area. Mercury levels in fish ranged from 13 to 520 ng/g. Historical fish residue data are limited from the Portland Harbor superfund site, what data is available is over a decade old, generally consisted of only a few fish (< or = 3) and analyses quantified only a few PCB congeners (< 3).

Family involvement in nursing homes: effects on stress and well-being

While it is clear that families remain involved in the lives of loved ones following placement in a nursing home, little research has examined whether visiting and the provision of care has effects on the emotional stress and psychological well-being of family members. Utilizing pre-placement and post-placement data from the Caregiver Stress and Coping Study (n = 185) as well as a theoretical framework to delineate the manifestation of caregiver stress (i.e., the stress process model), the goal of this analysis was to determine whether frequency of visits and provision of personal and instrumental activities of daily living assistance following institutionalization were related to post-placement emotional distress, family conflict, and psychological well-being among family members. Following control of a wide array of pre-placement and post-placement covariates, multiple regression models found that visiting was negatively associated with post-placement role overload; moreover, the provision of instrumental activities of daily living help was negatively related to loss of intimate exchange at post-placement. The results suggest that family involvement following institutionalization may operate differently than when in the community, and add to the literature emphasizing the positive implications of family involvement in residential long-term care.

Catalytic activity is required for calcium/calmodulin-dependent protein kinase IV to enter the nucleus

Calcium/calmodulin-dependent protein kinase IV (CaMKIV) is a nuclear protein kinase that responds to acute rises in intracellular calcium by phosphorylating and activating proteins involved in transcription. Consistent with these roles, CaMKIV is found predominantly in the nucleus of cells in which it is expressed. Here we evaluate nuclear entry of CaMKIV and demonstrate that the protein kinase homology domain is both necessary and sufficient for nuclear localization. Unexpectedly, although catalytic activity is required for nuclear translocation, it is not required for CaMKIV to interact with the nuclear adaptor protein, importin-alpha. Because the catalytically inactive molecules remain in the cytoplasm, these data suggest that this interaction is not sufficient for nuclear entry. We evaluated a role for other proteins known to interact with CaMKIV in regulation of its nuclear entry. Although our data do not support a role for calmodulin or protein phosphatase 2A, the catalytically inactive CaMKIV proteins interact more avidly with CaM-dependent protein kinase kinase (CaMKK), which is restricted to the cytoplasm. We find that the catalytically inactive proteins do not inhibit nuclear entry of wild-type CaMKIV but do inhibit the ability of the wild-type protein kinase to stimulate cyclic AMP response element-binding protein-mediated transcription. Because activation loop phosphorylation is required for the transcriptional roles of CaMKIV, these data suggest that CaMKK phosphorylation of CaMKIV may occur in the cytoplasm. We propose that sequestration of CaMKK may be the molecular mechanism by which catalytically inactive mutants of CaMKIV exert their "dominant-negative" functions within the cell.

Defective signaling in a subpopulation of CD4(+) T cells in the absence of Ca(2+)/calmodulin-dependent protein kinase IV

Ca(2+)/calmodulin-dependent protein kinase IV-deficient (CaMKIV(-/-)) mice have been used to investigate the role of this enzyme in CD4(+) T cells. We identify a functional defect in a subpopulation of CD4(+) T cells, characterized by a cell surface marker profile usually found on memory phenotype CD4(+) T cells. Upon T-cell receptor engagement, the mutant cells produce diminished levels of interleukin-2 (IL-2), IL-4, and gamma interferon protein and mRNA. The defect is secondary to an inability to phosphorylate CREB and to induce CREB-dependent immediate-early genes, including c-jun, fosB, fra2, and junB, which are required for cytokine gene induction. In contrast, stimulated naive CD4(+) T cells from CaMKIV(-/-) mice show normal CREB phosphorylation, induction of immediate-early genes, and cytokine production. Thus, in addition to defining an important signaling role for CaMKIV in a subpopulation of T cells, we identify differential signaling requirements for cytokine production between naive T cells and T cells that express cell surface markers characteristic of the memory phenotype.

Bioavailable organochlorine pesticides in a semi-arid region of eastern Oregon, USA, as determined by gas chromatography with electron-capture detection

A group of dissolved-bioavailable organochlorine (OC) pesticides and inorganic anions in water and total OC pesticides in sediments were measured in the Malheur Watershed, a semi-arid region in the western United States, over a 2-year period. OC pesticide levels were compared with those from a 1990 study of the lower section of the river, the most recent data available. After calculating the dissolved fraction from the 1990, study it seems that DDD and dieldrin levels have decreased in the water by 50-70%, while DDE and DDT have changed little. Although banned nearly 30 years ago, DDT is still persistent throughout the Malheur River basin/watershed because it was found in all water samples tested. All of the OC pesticides tested during the 2-year study are well below the criterion continuous concentration for aquatic community exposure as defined by the U.S. Environmental Protection Agency (EPA). OC pesticides appear to be decreasing, however, at lower Ontario there remains a human health risk (EPA Human Health Risk Water Quality Criteria) for DDT, because this criteria includes daily consumption of water and fish from the river. Overall, although the upper forest watershed sites have lower OC pesticide concentrations, they represent an important contribution to the total DDT load to this watershed, a source not previously acknowledged. The large increase in DDT and sigmaDDT between the Ontario sites may indicate a possible historical point source of contamination or historical preferential deposition of contamination. Normalized sediment (sigmaDDT/organic carbon) strongly correlates with dissolved water sigmaDDT.

Analgesia induced by chronic nicotine infusion in rats: differences by gender and pain test

RATIONALE

Acute administration of nicotine induces analgesia with subsequent development of tolerance. In human studies, females are less sensitive to the analgesic effects of nicotine than males. Few previous animal studies have investigated analgesic effects of chronic nicotine administration or addressed gender differences.

OBJECTIVES

To investigate whether chronic administration of nicotine induces analgesia in male and female rats as assessed by a battery of standard pain assays, if tolerance develops, and if hyperalgesia occurs following cessation of nicotine.

METHODS

Nicotine (free base; 6 mg/kg/day i.v.) or saline was administered for 2 weeks via implanted osmotic pumps. Pain behavior was assessed before, during, and for 3 weeks after nicotine infusion by measuring tail flick latency, hot-plate latency, and thermal paw withdrawal latency. The paw-withdrawal threshold to non-noxious mechanical stimuli was also measured. Effects of nicotine infusion, gender, and time were assessed by three-way analyses of variance.

RESULTS

Both male and female rats exhibited a comparable degree of analgesia in the hot-plate test with development of tolerance during the 2-week infusion period. Males, but not females, showed analgesia in the tail flick test. Analgesia was not observed for thermally evoked paw withdrawal in either males or females, nor did nicotine affect non-noxious mechanically evoked paw withdrawals. Males and females showed cessation of weight gain during the first week of nicotine infusion.

CONCLUSIONS

Chronic nicotine-induced analgesia was confirmed in both male and female rats as assessed using the hot-plate test which reflects integrated pain behavior. Males, but not females, exhibited analgesia in a nociceptive withdrawal reflex test (tail flick), indicating that nicotine-induced analgesia may depend on both the type of pain test and gender. The lack of nicotine-induced analgesia assessed by the tail flick reflex test in female rats is consistent with recent human studies showing that nicotine reduces pain elicited by brief noxious cutaneous stimulation in male but not female subjects.

Nedocromil sodium inhibits canine adenovirus bronchiolitis in beagle puppies

Nedocromil sodium is a nonsteroidal anti-inflammatory drug used to control asthmatic attacks. Our hypothesis is that nedocromil sodium inhibits virus-induced airway inflammation, a common trigger of asthma. We nebulized nedocromil sodium into beagle dogs (n = 10, mean +/- SEM ages: 149 +/- 13 days) before and after inoculation with canine adenovirus type 2 (CAV2). Control dogs (n = 10) received saline aerosols and were either infected with CAV2 (Sal/CAV2, n = 7, mean +/- SEM ages: 140 +/- 11 days) or were not infected (Sal/Sal, n = 3, ages: 143 +/- 0 days). All dogs were anesthetized with choralose (80 mg/kg i.v.), intubated, and mechanically ventilated. Pulmonary function tests and bronchoalveolar lavage (BAL) were performed using standard techniques. Pulmonary function tests revealed no significant change between the nedocromil sodium and non-nedocromil-treated groups. The percentage of infected bronchioles was quantitated as the number of inflamed airways of 40 bronchioles examined times 100 for each dog. Nedocromil-treated dogs had significantly (p < 0.05) less mucosal inflammation (mean +/- SEM, 39% +/- 5%), epithelial denudation (36% +/- 5%), and BAL neutrophilia (11 +/- 3) than did Sal/CAV2 dogs (51% +/- 6%, 57% +/- 4%, and 33% +/- 8%, respectively). We concluded that pretreatment with nedocromil sodium aerosols attenuated CAV2-induced airway inflammation in these beagle puppies.

Speciation of iodide, iodine, and iodate in environmental matrixes by inductively coupled plasma atomic emission spectrometry using in situ chemical manipulation

Dissolved iodine, iodide, and iodate are determined in environmental matrixes by in situ chemical manipulation and inductively coupled plasma atomic emission spectrometry (ICPAES). The method uses equipment commonly available to most laboratories involved in environmental inorganic analysis. Total dissolved iodine, iodide, and iodate are determined by ICPAES using iodine vapor generation. Total iodine is determined directly by ICPAES after filtration. Total dissolved iodide (I-) is oxidized in situ to iodine by the addition of sodium nitrite in sulfuric acid in a simplified continuous flow manifold. Iodate is determined by prereduction at the instrument before analysis by the in situ oxidation ICPAES procedure. A standard nebulizer produces the gas-liquid separation of the total iodine, which is then quantified by ICPAES at 206.16 nm. The instrument detection limit for the iodine analysis was 0.04 microgram/mL. Recoveries from seawater, saltwater, and freshwater standard reference materials ranged from 85 to 118% and averaged 98%. For samples containing both iodine and iodide, the total is determined with in situ oxidation, iodine is determined without the oxidizing reagents, and iodine is calculated from the difference. For samples containing all 3 species, pre-reduction is used and the iodine and iodide concentrations are subtracted for quantitation of iodate. The analysis is selective for these 3 species (I-, I2, and IO3). A group of 20-30 samples may be analyzed and quantitated for all 3 individual, commonly occurring iodide species in less than 1 h. The procedure is considerably faster than any other reported techniques. This method is especially well-suited to the analysis of small environmental samples.

Intrathoracic and concurrent orthopedic injury associated with traumatic rib fracture in cats: 75 cases (1980-1998)

OBJECTIVE

To characterize rib, intrathoracic, and concurrent orthopedic injuries, and prognosis associated with traumatic rib fracture in cats.

DESIGN

Retrospective study.

ANIMALS

75 cats.

PROCEDURE

Medical records from January 1980 to August 1998 were examined for cats with traumatic rib fracture. Signalment, cause of trauma, interval from trauma to evaluation at a veterinary teaching hospital, referral status and date, method of diagnosis, duration of hospitalization, number and location of rib fractures, presence of flail chest, costal cartilage involvement, intrathoracic and concurrent orthopedic injury, and clinical outcome were reviewed.

RESULTS

Median age was 3 years. Twenty-five (58%) cats with reported cause of trauma were injured by interaction with another animal. Forty-seven (78%) cats that were treated survived. Cats that died had a median duration of hospitalization of < 1 day. Ten (13%) cats had flail chest. Sixty-five (87%) cats had intrathoracic injury (median, 2 injuries). Nine (100%) cats without detected intrathoracic injury that were treated survived. Thirty-five (47%) cats had concurrent orthopedic injury. Cats with flail chest, pleural effusion, or diaphragmatic hernia were significantly more likely to die than cats without each injury.

CONCLUSIONS AND CLINICAL RELEVANCE

Traumatic rib fracture in cats is associated with intrathoracic and concurrent orthopedic injury. Aggressive treatment of cats with traumatic rib fracture is warranted, because the prognosis is generally favorable. Diagnosis and treatment of intrathoracic injury associated with traumatic rib fracture in cats should precede management of concurrent orthopedic injury.

Global distribution of crustal magnetization discovered by the mars global surveyor MAG/ER experiment

Vector magnetic field observations of the martian crust were acquired by the Mars Global Surveyor (MGS) magnetic field experiment/electron reflectometer (MAG/ER) during the aerobraking and science phasing orbits, at altitudes between approximately 100 and 200 kilometers. Magnetic field sources of multiple scales, strength, and geometry were observed. There is a correlation between the location of the sources and the ancient cratered terrain of the martian highlands. The absence of crustal magnetism near large impact basins such as Hellas and Argyre implies cessation of internal dynamo action during the early Naochian epoch ( approximately 4 billion years ago). Sources with equivalent magnetic moments as large as 1.3 x 10(17) ampere-meter2 in the Terra Sirenum region contribute to the development of an asymmetrical, time-variable obstacle to solar wind flow around Mars.

Determining the geographic origin of potatoes with trace metal analysis using statistical and neural network classifiers

The objective of this research was to develop a method to confirm the geographical authenticity of Idaho-labeled potatoes as Idaho-grown potatoes. Elemental analysis (K, Mg, Ca, Sr, Ba, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, S, Cd, Pb, and P) of potato samples was performed using ICPAES. Six hundred eight potato samples were collected from known geographic growing sites in the U.S. and Canada. An exhaustive computational evaluation of the 608 x 18 data sets was carried out using statistical (PCA, CDA, discriminant function analysis, and k-nearest neighbors) and neural network techniques. The neural network classification of the samples into two geographic regions (defined as Idaho and non-Idaho) using a bagging technique had the highest percentage of correct classifications, with a nearly 100% degree of accuracy. We report the development of a method combining elemental analysis and neural network classification that may be widely applied to the determination of the geographical origin of unprocessed, fresh commodities.

Ca2+/calmodulin-dependent protein kinase IV and calcium signaling

Ca2+/calmodulin dependent protein kinase IV (CaMKIV) is a multifunctional, serine-threonine protein kinase that is activated in the presence of increased intracellular calcium (Ca2+). CaMKIV is a potent mediator of Ca2+ induced gene expression, primarily through its ability to phosphorylate and activate transcription factors such as CREB. CaMKIV-dependent activation of CREB is a key event in the expression of genes involved in the processes of T-cell activation and neuronal long term potentiation. The focus of this review is to describe the biochemical regulation of CaMKIV and examine how CaMKIV activates transcription in response to calcium in both cell and animal models.

Components of a calmodulin-dependent protein kinase cascade. Molecular cloning, functional characterization and cellular localization of Ca2+/calmodulin-dependent protein kinase kinase beta

Ca2+/calmodulin-dependent protein kinases I and IV (CaMKI and CaMKIV, respectively) require phosphorylation on an equivalent single Thr in the activation loop of subdomain VIII for maximal activity. Two distinct CaMKI/IV kinases, CaMKKalpha and CaMKKbeta, were purified from rat brain and partially sequenced (Edelman, A. M., Mitchelhill, K., Selbert, M. A., Anderson, K. A., Hook, S. S., Stapleton, D., Goldstein, E. G., Means, A. R., and Kemp, B. E. (1996) J. Biol. Chem. 271, 10806-10810). We report here the cloning and sequencing of cDNAs for human and rat CaMKKbeta, tissue and regional brain localization of CaMKKbeta protein, and mRNA and functional characterization of recombinant CaMKKbeta in vitro and in Jurkat T cells. The sequences of human and rat CaMKKbeta demonstrate 65% identity and 80% similarity with CaMKKalpha and 30-40% identity with CaMKI and CaMKIV themselves. CaMKKbeta is broadly distributed among rat tissues with highest levels in CaMKIV-expressing tissues such as brain, thymus, spleen, and testis. In brain, CaMKKbeta tracks more closely with CaMKIV than does CaMKKalpha. Bacterially expressed CaMKKbeta undergoes intramolecular autophosphorylation, is regulated by Ca2+/CaM, and phosphorylates CaMKI and CaMKIV on Thr177 and Thr200, respectively. CaMKKbeta activates both CaMKI and CaMKIV when coexpressed in Jurkat T cells as judged by phosphorylated cAMP response element-binding protein-dependent reporter gene expression. CaMKKbeta activity is enhanced by elevation of intracellular Ca2+, although substantial activity is observed at the resting Ca2+ concentration. The strict Ca2+ requirement of CaMKIV-dependent phosphorylation of cAMP response element-binding protein, is therefore controlled at the level of CaMKIV rather than CaMKK.

Lunar surface magnetic fields and their interaction with the solar wind: results from lunar prospector

The magnetometer and electron reflectometer experiment on the Lunar Prospector spacecraft has obtained maps of lunar crustal magnetic fields and observed the interaction between the solar wind and regions of strong crustal magnetic fields at high selenographic latitude (30 degreesS to 80 degreesS) and low ( approximately 100 kilometers) altitude. Electron reflection maps of the regions antipodal to the Imbrium and Serenitatis impact basins, extending to 80 degreesS latitude, show that crustal magnetic fields fill most of the antipodal zones of those basins. This finding provides further evidence for the hypothesis that basin-forming impacts result in magnetization of the lunar crust at their antipodes. The crustal magnetic fields of the Imbrium antipode region are strong enough to deflect the solar wind and form a miniature (100 to several hundred kilometers across) magnetosphere, magnetosheath, and bow shock system.

Neuromuscular blocking and cardiovascular effects of Org 9487, a new short-acting aminosteroidal blocking agent, in anaesthetized animals and in isolated muscle preparations

This study was undertaken to investigate the neuromuscular blocking profile and cardiovascular effects of Org 9487, a new aminosteroidal, non-depolarizing, neuromuscular blocking agent structurally related to vecuronium, in anaesthetized animals and in isolated muscle preparations. In in vitro functional assays of neuromuscular blocking activity, Org 9487 was between eight and 15 times less potent than vecuronium. In cats and monkeys the potency of Org 9487 was approximately one-seventh and one-twentieth, respectively, that of vecuronium. In both species, Org 9487 induced rapidly developing (onset times between 1.5 min and 1.9 min) neuromuscular paralysis, which was shorter-lasting than that of vecuronium and similar in time course to suxamethonium. The vagal: neuromuscular blocking dose ratio for Org 9487 was 3 and ganglion block was seen only at approximately 20 times the neuromuscular blocking dose. There was no evidence in the rat that Org 9487, administered at doses up to 3 mg kg-1, inhibited noradrenaline re-uptake. In anaesthetized dogs, Org 9487 (3 x 90% blocking dose) induced only relatively small and transient haemodynamic effects. The administration of clinically relevant doses of neostigmine or pyridostigmine shortened the time-course profile of Org 9487, even when administered during profound neuromuscular block. In animals, Org 9487 is a low potency, nondepolarizing neuromuscular blocking agent with a time course profile similar to that of suxamethonium. Although Org 9487 is less selective than vecuronium for the neuromuscular junction, it is unlikely to produce prohibitive cardiovascular side effects in man.

A signaling complex of Ca2+-calmodulin-dependent protein kinase IV and protein phosphatase 2A

Stimulation of T lymphocytes results in a rapid increase in intracellular calcium concentration ([Ca2+]i) that parallels the activation of Ca2+-calmodulin-dependent protein kinase IV (CaMKIV), a nuclear enzyme that can phosphorylate and activate the cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB). However, inactivation of CaMKIV occurs despite the sustained increase in [Ca2+]i that is required for T cell activation. A stable and stoichiometric complex of CaMKIV with protein serine-threonine phosphatase 2A (PP2A) was identified in which PP2A dephosphorylates CaMKIV and functions as a negative regulator of CaMKIV signaling. In Jurkat T cells, inhibition of PP2A activity by small t antigen enhanced activation of CREB-mediated transcription by CaMKIV. These findings reveal an intracellular signaling mechanism whereby a protein serine-threonine kinase (CaMKIV) is regulated by a tightly associated protein serine-threonine phosphatase (PP2A).

Magnetic Field and Plasma Observations at Mars: Initial Results of the Mars Global Surveyor Mission

The magnetometer and electron reflectometer investigation (MAG/ER) on the Mars Global Surveyor spacecraft has obtained magnetic field and plasma observations throughout the near-Mars environment, from beyond the influence of Mars to just above the surface (at an altitude of approximately 100 kilometers). The solar wind interaction with Mars is in many ways similar to that at Venus and at an active comet, that is, primarily an ionospheric-atmospheric interaction. No significant planetary magnetic field of global scale has been detected to date (<2 x 10(21) Gauss-cubic centimeter), but here the discovery of multiple magnetic anomalies of small spatial scale in the crust of Mars is reported.

Magnetic Field and Plasma Observations at Mars: Initial Results of the Mars Global Surveyor Mission

The magnetometer and electron reflectometer investigation (MAG/ER) on the Mars Global Surveyor spacecraft has obtained magnetic field and plasma observations throughout the near-Mars environment, from beyond the influence of Mars to just above the surface (at an altitude of approximately 100 kilometers). The solar wind interaction with Mars is in many ways similar to that at Venus and at an active comet, that is, primarily an ionospheric-atmospheric interaction. No significant planetary magnetic field of global scale has been detected to date (<2 x 10(21) Gauss-cubic centimeter), but here the discovery of multiple magnetic anomalies of small spatial scale in the crust of Mars is reported.

Determination of trace boron in microsamples of biological tissues

A benign-by-design method for the determination of boron (B) in microsamples of biological tissues was developed. This is a simple, automated, microdigestion method. Use of reagents and generation of waste are minimized, and the use of toxic/hazardous reagents is eliminated as compared to currently available B methodology. Microsamples are accommodated by the method; 100-400 mg samples were used in this study. B is determined by inductively coupled plasma atomic emission spectrometry (ICPAES) at 249.678 nm. The instrument detection limit for B is 0.01 microgram/mL. Interference studies have been investigated for 21 common elements. Over 250 analyses of standard reference materials were analyzed during the study duration. Recoveries for a series of biological tissues, both plant and animal, ranged from 82-104%.

Defective survival and activation of thymocytes in transgenic mice expressing a catalytically inactive form of Ca2+/calmodulin-dependent protein kinase IV

We have generated transgenic mice that express a catalytically inactive form of Ca2+/calmodulin-dependent protein kinase IV (CaMKIV) specifically in thymic T cells. The presence of this protein results in a markedly reduced thymic cellularity, although the distribution of the remaining cells is normal based on evaluation of the CD4 and CD8 cell surface antigens that are used to gauge T cell development. Isolated thymic T cells from the transgenic mice also show a dramatically decreased survival rate when evaluated in culture under conditions that do not favor activation. When challenged with an activating stimulus such as alpha-CD3 or a combination of phorbol ester plus ionophore, the cells are severely compromised in their ability to produce the cytokine interleukin-2 (IL-2). Reduction of IL-2 production is secondary to the inability to phosphorylate the cAMP response element binding protein, CREB, and induce expression of the immediate early genes such as Fos B that are required to transactivate the IL-2 promoter. Because transgene expression was regulated by the proximal promoter of the murine lck gene and this promoter is inactivated in T cells that exit the thymus, the mutant hCaMKIV is not present in peripheral T cells. Consequently, T lymphocytes present in the spleen can be activated normally in response to either stimulus mentioned above, demonstrating that the effects of the inactive CaMKIV on activation are reversible. Our results suggest that CaMKIV may represent a physiologically relevant CREB kinase in T cells and that the enzyme is also required to ensure normal expansion of T cells in the thymus. Whereas the pathway responsible for this latter role is yet to be elucidated, it is unlikely to include CREB phosphorylation.

Effects of resistive training on strength gains in older adults

This study was designed to evaluate the effects of a moderate intensity, 16-week resistive strength training program on the rate and pattern of strength changes in trunk, upper, and lower extremity muscle groups. This study was also designed to determine the importance of muscle mass on strength gains during a training intervention with older adults. A repeated measures experimental design was employed with 43 experimental (ES) and 42 comparison subjects (CS). The active older sample had a relatively high level of strength for their age (72.1 yr) and had no contraindications for strength training. The ES trained five upper, three trunk, and three lower extremity muscle groups. Both ES and CS received pre- and post-testing assessments for muscle strength, muscle morphology, body composition, flexibility, and balance. The ES also received intermittent testing for one repetition maximum (1RM). ANOVA and Scheffé HSD tests were used to evaluate the data. The ES experienced significant strength gains (over 41% for each body segment) following the intervention. The rate of gain in this study was less than but the absolute strength gain was reasonably similar to values reported by studies in the literature [1,2]. There was no change in muscle mass (p>.05) following training. These results suggests that stronger active older adults have a muscle mass sufficient for greater strength and that training enables them to use available muscle mass more effectively. These results further suggest that muscle hypertrophy may be possible following strength training but it is not always necessary for strength improvement in older adults.

Regulation and properties of the rat Ca2+/calmodulin-dependent protein kinase IV gene and its protein products

Ca2+/calmodulin-dependent protein kinase IV (CaMKIV) is a monomeric multifunctional enzyme that is expressed only in subanatomical portions of the brain, T lymphocytes, and postmeiotic male germ cells. It is present in the nucleus of the cells in which it is expressed and can phosphorylate and activate the cyclic AMP response element binding proteins CREB and CREM tau in a manner analogous to protein kinase A. In the absence of Ca2+/calmodulin, CaMKIV is inactive. Activation requires three events: 1) binding of Ca2+/calmodulin; 2) phosphorylation of a single threonine residue present in the activation loop by a separate protein kinase that is also Ca2+/calmodulin-dependent; and 3) autophosphorylation of serine residues present in the extreme N-terminus that is required to relieve a novel form of autoinhibition. The gene for rat CaMKIV has been cloned and found to span 42 kb of DNA. The gene encodes three proteins: namely, the alpha and beta forms of CaMKIV that differ only in that the beta form contains a 28 amino acid N-terminal extension as well as calspermin. Calspermin is the C-terminal 169 amino acids of CaMKIV that binds Ca2+/calmodulin and is expressed only in postmeiotic male germ cells. The promoter for calspermin resides in the penultimate intron of the CaMKIV gene and is regulated by two CREs. This promoter is sufficient to faithfully target expression of a reporter gene to the postmeiotic male germ cells of transgenic mice. Transgene expression can be induced in cells from the transgenic mice that do not normally express it by transfection of CREM tau and CaMKIV. These data suggest that rearrangement of chromatin during meiosis together with the expression of CREM tau at high levels are sufficient to control expression of the calspermin promoter during spermatogenesis. On the other hand, the developmental expression of CaMKIV in brain and thymus appears to be controlled by thyroid hormone mediated via the thyroid hormone receptor alpha. In T lymphocytes, CaMKIV will phosphorylate CREB in response to signals that result in T cell activation. Transgenic mice that express a kinase minus mutant of CaMKIV specifically in thymic T cells show a marked reduction of total thymic cellularity. The remaining T cells undergo a much greater than normal rate of spontaneous apoptosis when placed in culture. These cells fail to generate the signals to phosphorylate CREB and produce significantly less of the cytokine Interleukin-2 (IL-2) in response to agents that either increase intracellular Ca2+ and/or activate protein kinase C. Collectively, the data suggest that CaMKIV may be involved both in preventing apoptosis during T cell development and also in the early cascade of events that is required to activate the mature T cells in response to a mitogenic stimulus.