A gamma-glutamyl peptide isolated from onion (Allium cepa L.) by bioassay-guided fractionation inhibits resorption activity of osteoclasts

One gram of onion added to the food of rats inhibits significantly (p < 0.05) bone resorption as assessed by the urinary excretion of tritium released from bone of 9-week-old rats prelabeled with tritiated tetracycline from weeks 1 to 6. To isolate and identify the bone resorption inhibiting compound from onion, onion powder was extracted and the extract fractionated by column chromatography and medium-pressure liquid chromatography. A single active peak was finally obtained by semipreparative high-performance liquid chromatography. The biological activity of the various fractions was tested in vitro on the activity of osteoclasts to form resorption pits on a mineralized substrate. Medium, containing the various fractions or the pure compound, was added to osteoclasts of new-born rats settled on ivory slices. After 24 h of incubation, the tartrate-resistant acid phosphatase positive multinucleated cells, that is, osteoclasts, were counted. Subsequently, the number of resorption pits was determined. Activity was calculated as the ratio of resorption pits/osteoclasts and was compared to a negative control, that is, medium containing 10% fetal bovine serum only and to calcitonin (10(-12) M) as a positive control. Finally, a single peak inhibited osteoclast activity significantly (p < 0.05). The structure of this compound was elucidated with high-performance liquid chromatography-electrospray ionization-mass spectrometry, time-of-flight electrospray ionization mass spectrometry, and nuclear magnetic resonance spectroscopy. The single peak was identified as gamma-L-glutamyl-trans-S-1-propenyl-L-cysteine sulfoxide (GPCS). It has a molecular mass of 306 Da and inhibits dose-dependently the resorption activity of osteoclasts, the minimal effective dose being approximately 2 mM. As no other peak displayed inhibitory activity, it likely is responsible for the effect of onion on bone resorption.

Studies on the reduction of the nitro group in 3-aryl-2-methylene-4-nitro-alkanoates afforded by the Baylis-Hillman adducts: Synthesis of 4-aryl-3-methylene-2-pyrrolidinones and 3-(1-alkoxycarbonyl-vinyl)-1H-indole-2-carboxylates

The formation of substituted 2-pyrrolidinones and indoles by the reduction of the secondary nitro group in appropriate 3-aryl-2-methylene-4-nitroalkanoates afforded by Baylis-Hillman chemistry via different reducing agents is described. The 3-aryl-2-methylene-4-nitroalkanoate obtained from SN2 nucleophilic reaction between the acetate of Baylis-Hillman adducts and ethyl nitroacetate upon reduction with indium-HCl furnishes a mixture of cis and trans substituted phenyl-3-methylene-2-pyrrolidinones. In contrast, similar reductions of analogous substrates derived from nitroethane stereoselectively furnished only the trans substituted phenyl-3-methylene-2-pyrrolidinones. On the other hand the SnCl2.2H2O-promoted reductions of substrates derived from nitro ethylacetate give oxime derivatives while the ones obtained from nitroethane yield a mixture of cis and trans 4-aryl-3-methylene-2-pyrrolidinones. Alternatively, the SnCl2.2H2O-promoted reduction of substituted 2-nitrophenyl-2-methylene-alkanoate furnished from ethyl nitroacetate yields 3-(1-alkoxycarbonyl-vinyl)-1H-indole-2-carboxylate while indium-promoted reaction of this substrate leads to a complex mixture. Analogous reactions with SnCl2.2H2O of substituted 2-nitrophenyl-2-methylene-alkanoate obtained from nitroethane yield 4-alkyl-3-methylene-2-quinolones in moderate yields

Anti-eosinophil activity and clinical efficacy of the CRTH2 antagonist OC000459 in eosinophilic esophagitis

BACKGROUND: Eosinophilic esophagitis (EoE) is a chronic, Th2-type inflammatory disease. Chemoattractant receptor-homologous molecule on Th2 cells (CRTH2) is a prostaglandin D(2) (PGD(2)) receptor, expressed by Th2 cells and other inflammatory cells, including eosinophils and basophils, that mediates chemotaxis and activation. OC000459 is a selective CRTH2 antagonist and would be expected to suppress eosinophilic tissue inflammation. The purpose of this study was to evaluate the efficacy and safety of an OC000459 monotherapy in adult patients with active, corticosteroid-dependent or corticosteroid-refractory EoE. METHODS: In this randomized, double-blind, placebo-controlled trial, 26 adult patients (m/f = 22/4; mean age 41 years, range 22-69 years) with active EoE, dependent or resistant to corticosteroids, were treated either with 100 mg OC000459 (n = 14) or placebo (n = 12) twice daily. Pre- and post-treatment disease activity was assessed clinically, endoscopically, histologically, and via biomarkers. The primary end point was the reduction in esophageal eosinophil infiltration. RESULTS: After an 8-week OC000459 treatment, the esophageal eosinophil load decreased significantly, from 114.83 to 73.26 eosinophils per high-power field [(eos/hpf), P = 0.0256], whereas no reduction was observed with placebo (102.80-99.47 eos/hpf, P = 0.870). With OC000459, the physician's global assessment of disease activity improved from 7.13 to 5.18 (P = 0.035). OC000459 likewise reduced extracellular deposits of eosinophil peroxidase and tenascin C, the effects not seen with placebo. No serious adverse events were observed. CONCLUSIONS: An 8-week treatment with the CRTH2-antagonist, OC000459, exerts modest, but significant, anti-eosinophil and beneficial clinical effects in adult patients with active, corticosteroid-dependent or corticosteroid-refractory EoE and is well tolerated.

Diversity and function of mutations in p450 oxidoreductase in patients with Antley-Bixler syndrome and disordered steroidogenesis

P450 oxidoreductase (POR) is the obligatory flavoprotein intermediate that transfers electrons from reduced nicotinamide adenine dinucleotide phosphate (NADPH) to all microsomal cytochrome P450 enzymes. Although mouse Por gene ablation causes embryonic lethality, POR missense mutations cause disordered steroidogenesis, ambiguous genitalia, and Antley-Bixler syndrome (ABS), which has also been attributed to fibroblast growth factor receptor 2 (FGFR2) mutations. We sequenced the POR gene and FGFR2 exons 8 and 10 in 32 individuals with ABS and/or hormonal findings that suggested POR deficiency. POR and FGFR2 mutations segregated completely. Fifteen patients carried POR mutations on both alleles, 4 carried mutations on only one allele, 10 carried FGFR2 or FGFR3 mutations, and 3 patients carried no mutations. The 34 affected POR alleles included 10 with A287P (all from whites) and 7 with R457H (four Japanese, one African, two whites); 17 of the 34 alleles carried 16 "private" mutations, including 9 missense and 7 frameshift mutations. These 11 missense mutations, plus 10 others found in databases or reported elsewhere, were recreated by site-directed mutagenesis and were assessed by four assays: reduction of cytochrome c, oxidation of NADPH, support of 17alpha-hydroxylase activity, and support of 17,20 lyase using human P450c17. Assays that were based on cytochrome c, which is not a physiologic substrate for POR, correlated poorly with clinical phenotype, but assays that were based on POR's support of catalysis by P450c17--the enzyme most closely associated with the hormonal phenotype--provided an excellent genotype/phenotype correlation. Our large survey of patients with ABS shows that individuals with an ABS-like phenotype and normal steroidogenesis have FGFR mutations, whereas those with ambiguous genitalia and disordered steroidogenesis should be recognized as having a distinct new disease: POR deficiency.

Endocardial Ablation to Eliminate Epicardial Arrhythmia Substrate in Scar-Related Ventricular Tachycardia

OBJECTIVES We evaluated the feasibility and safety of epicardial substrate elimination using endocardial radiofrequency (RF) delivery in patients with scar-related ventricular tachycardia (VT). BACKGROUND Epicardial RF delivery is limited by fat or associated with bleeding, extra-cardiac damages, coronary vessels and phrenic nerve injury. Alternative ablation approaches may be desirable. METHODS Forty-six patients (18 ischemic cardiomyopathy [ICM], 13 non-ischemic dilated cardiomyopathy [NICM], 15 arrhythmogenic right ventricular cardiomyopathy [ARVC]) with sustained VT underwent combined endo- and epicardial mapping. All patients received endocardial ablation targeting local abnormal ventricular activities in the endocardium (Endo-LAVA) and epicardium (Epi-LAVA), followed by epicardial ablation if needed. RESULTS From a total of 173 endocardial ablations targeting Epi-LAVA at the facing site, 48 (28%) applications (ICM: 20/71 [28%], NICM: 3/39 [8%], ARVC: 25/63 [40%]) successfully eliminated the Epi-LAVA. Presence of Endo-LAVA, most delayed and low bipolar amplitude of Epi-LAVA, low unipolar amplitude in the facing endocardium, and Epi-LAVA within a wall thinning area at CT scan were associated with successful ablation. Endocardial ablation could abolish all Epi-LAVA in 4 ICM and 2 ARVC patients, whereas all patients with NICM required epicardial ablation. Endocardial ablation was able to eliminate Epi-LAVA at least partially in 15 (83%) ICM, 2 (13%) NICM, and 11 (73%) ARVC patients, contributing to a potential reduction in epicardial RF applications. Pericardial bleeding occurred in 4 patients with epicardial ablation. CONCLUSIONS Elimination of Epi-LAVA using endocardial RF delivery is feasible and may be used first to reduce the risk of epicardial ablation.

Trigger activity more than three years after left atrial linear ablation without pulmonary vein isolation in patients with atrial fibrillation.

OBJECTIVES The aim of this study was to analyze trigger activity in the long-term follow-up after left atrial (LA) linear ablation. BACKGROUND Interventional strategies for curative treatment of atrial fibrillation (AF) are targeted at the triggers and/or the maintaining substrate. After substrate modification using nonisolating linear lesions, the activity of triggers is unknown. METHODS With the LA linear lesion concept, 129 patients were treated using intraoperative ablation with minimal invasive surgical techniques. Contiguous radiofrequency energy-induced lesion lines involving the mitral annulus and the orifices of the pulmonary veins without isolation were placed under direct vision. RESULTS After a mean follow-up of 3.6 +/- 0.4 years, atrial ectopy, atrial runs, and reoccurrence of AF episodes were analyzed by digital 7-day electrocardiograms in 30 patients. Atrial ectopy was present in all patients. Atrial runs were present in 25 of 30 patients (83%), with a median number of 9 runs per patient/week (range 1 to 321) and a median duration of 1.2 s/run (range 0.7 to 25), without a significant difference in atrial ectopy and atrial runs between patients with former paroxysmal (n = 17) or persistent AF (n = 13). Overall, 87% of all patients were completely free from AF without antiarrhythmic drugs. CONCLUSIONS A detailed rhythm analysis late after specific LA linear lesion ablation shows that trigger activity remains relatively frequent but short and does not induce AF episodes in most patients. The long-term success rate of this concept is high in patients with paroxysmal or persistent AF.

The substrate degradome of meprin metalloproteases reveals an unexpected proteolytic link between meprin β and ADAM10.

The in vivo roles of meprin metalloproteases in pathophysiological conditions remain elusive. Substrates define protease roles. Therefore, to identify natural substrates for human meprin α and β we employed TAILS (terminal amine isotopic labeling of substrates), a proteomics approach that enriches for N-terminal peptides of proteins and cleavage fragments. Of the 151 new extracellular substrates we identified, it was notable that ADAM10 (a disintegrin and metalloprotease domain-containing protein 10)-the constitutive α-secretase-is activated by meprin β through cleavage of the propeptide. To validate this cleavage event, we expressed recombinant proADAM10 and after preincubation with meprin β, this resulted in significantly elevated ADAM10 activity. Cellular expression in murine primary fibroblasts confirmed activation. Other novel substrates including extracellular matrix proteins, growth factors and inhibitors were validated by western analyses and enzyme activity assays with Edman sequencing confirming the exact cleavage sites identified by TAILS. Cleavages in vivo were confirmed by comparing wild-type and meprin(-/-) mice. Our finding of cystatin C, elafin and fetuin-A as substrates and natural inhibitors for meprins reveal new mechanisms in the regulation of protease activity important for understanding pathophysiological processes.

Observations of the northern seasonal polar cap on Mars: I. Spring sublimation activity and processes

Spring sublimation of the seasonal CO2 northern polar cap is a dynamic process in the current Mars climate. Phenomena include dark fans of dune material propelled out onto the seasonal ice layer, polygonal cracks in the seasonal ice, sand flow down slipfaces, and outbreaks of gas and sand around the dune margins. These phenomena are concentrated on the north polar erg that encircles the northern residual polar cap. The Mars Reconnaissance Orbiter has been in orbit for three Mars years, allowing us to observe three northern spring seasons. Activity is consistent with and well described by the Kieffer model of basal sublimation of the seasonal layer of ice applied originally in the southern hemisphere. Three typical weak spots have been identified on the dunes for escape of gas sublimed from the bottom of the seasonal ice layer: the crest of the dune, the interface of the dune with the interdune substrate, and through polygonal cracks in the ice. Pressurized gas flows through these vents and carries out material entrained from the dune. Furrows in the dunes channel gas to outbreak points and may be the northern equivalent of southern radially-organized channels ("araneiform" terrain), albeit not permanent. Properties of the seasonal CO2 ice layer are derived from timing of seasonal events such as when final sublimation occurs. Modification of dune morphology shows that landscape evolution is occurring on Mars today, driven by seasonal activity associated with sublimation of the seasonal CO2 polar cap.

Ribozyme-mediated reduction of wild-type and mutant cartilage oligomeric matrix protein (COMP) mRNA and protein.

Dominant-negative mutations in the homopentameric extracellular matrix glycoprotein cartilage oligomeric matrix protein (COMP) result in inappropriate intracellular retention of misfolded COMP in the rough endoplasmic reticulum of chondrocytes, causing chondrocyte cell death, which leads to two skeletal dysplasias: pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia (EDM1). COMP null mice show no adverse effects on normal bone development and growth, suggesting a possible therapy involving removal of COMP mRNA. The goal of this study was to assess the ability of a hammerhead ribozyme (Ribo56, designed against the D469del mutation) to reduce COMP mRNA expression. In COS7 cells transfected with plasmids that overexpress wild-type or mutant COMP mRNA and Ribo56, the ribozyme reduced overexpressed normal COMP mRNA by 46% and mutant COMP mRNA by 56% in a dose-dependent manner. Surprisingly, the use of recombinant adenoviruses to deliver wild-type or mutant COMP mRNA and Ribo56 simultaneously into COS7 cells proved problematic for the activity of the ribozyme to reduce COMP expression. However, in normal human costochondral cells (hCCCs) infected only with adenoviruses expressing Ribo56, expression of endogenous wild-type COMP mRNA was reduced in a dose-dependent manner by 50%. In chondrocytes that contain heterozygous COMP mutations (D469del, G427E and D511Y) that cause PSACH, Ribo56 was more effective at reducing COMP mRNA (up to 70%). These results indicate that Ribo56 is effective at reducing mutant and wild-type COMP levels in cells and suggests a possible mode of therapy to reduce the mutant protein load.

ROLE OF PROSTAGLANDIN E2 IN THE REGULATION OF PANCREATIC STELLATE CELLS HYPER ACTIVITY ASSOCIATED WITH PANCREATIC CANCER

Pancreatic cancer is one of the most lethal type of cancer due to its high metastasis rate and resistance to chemotherapy. Pancreatic fibrosis is a constant pathological feature of chronic pancreatitis and the hyperactive stroma associated with pancreatic cancer. Strong evidence supports an important role of cyclooxygenase-2 (COX-2) and COX-2 generated prostaglandin E2 (PGE2) during pancreatic fibrosis. Pancreatic stellate cells (PSC) are the predominant source of extracellular matrix production (ECM), thus being the key players in both diseases. Given this background, the primary objective is to delineate the role of PGE2 on human pancreatic stellate cells (PSC) hyper activation associated with pancreatic cancer. This study showed that human PSC cells express COX-2 and synthesize high levels of PGE2. PGE2 stimulated PSC migration and invasion; expression of extra cellular matrix (ECM) genes and tissue degrading matrix metallo proteinases (MMP) genes. I further identified the PGE2 EP receptor responsible for mediating these effects on PSC. Using genetic and pharmacological approaches I identified the receptor required for PGE2 mediates PSC hyper activation. Treating PSC with Specific antagonists against EP1, EP2 and EP4, demonstrated that blocking EP4 receptor only, resulted in a complete reduction of PGE2 mediated PSC activation. Furthermore, siRNA mediated silencing of EP4, but not other EP receptors, blocked the effects of PGE2 on PSC fibrogenic activity. Further examination of the downstream pathway modulators revealed that PGE2 stimulation of PSC involved CREB and not AKT pathway. The regulation of PSC by PGE2 was further investigated at the molecular level, with a focus on COL1A1. Collagen I deposition by PSC is one of the most important events in pancreatic cancer. I found that PGE2 regulates PSC through activation of COL1A1 expression and transcriptional activity. Downstream of PGE2, silencing of EP4 receptor caused a complete reduction of COL1A1 expression and activity supporting the role of EP4 mediated stimulation of PSC. Taken together, this data indicate that PGE2 regulates PSC via EP4 and suggest that EP4 can be a better therapeutic target for pancreatic cancer to reduce the extensive stromal reaction, possibly in combination with chemotherapeutic drugs can further kill pancreatic cancer cells.

Insulin-associated changes in carnitine palmitoyltransferase activity are mediated through the insulin-like growth factor I pathway in the cultured neonatal rat cardiac myocyte

The mitochondrial carnitine palmitoyltransferase (CPT) system is composed of two proteins, CPT-I and CPT-II, involved in the transport of fatty acids into the mitochondrial matrix to undergo $\beta$-oxidation. CPT-I is located outside the inner membrane and CPT-II is located on the inner aspect of the inner membrane. The CPT proteins are distinct with different molecular weights and activities. The malonyl-CoA sensitivity of CPT-I has been proposed as a regulatory step in $\beta$-oxidation. Using the neonatal rat cardiac myocyte, assays were designed to discriminate between these activities in situ using digitonin and Triton X-100. With this methodology, we are able to determine the involvement of the IGF-I pathway in the insulin-mediated increase in CPT activities. Concentrations of digitonin up to 25 $\mu$M fail to release citrate synthase from the mitochondrial matrix or alter the malonyl-CoA sensitivity of CPT-I. If the mitochondrial matrix was exposed, malonyl-CoA insensitive CPT-II would reduce malonyl-CoA sensitivity. In contrast to digitonin, Triton X-100 (0.15%) releases citrate synthase from the matrix and exposes CPT-II. CPT-II activity is confirmed by the absence of malonyl-CoA sensitivity. To examine the effects of various agents on the expression and/or activity of CPT, it is necessary to use serum-free medium to eliminate mitogenic effects of serum proteins. Comparison of different media to optimize CPT activity and cell viability resulted in the decision to use Dulbecco's Modified Eagle medium supplemented with transferrin. In three established models of cardiac hypertrophy using the neonatal rat cardiac myocyte there is a significant increase in CPT-I and CPT-II activity in the treated cells. Analogous to the situation seen in the hypertrophy model, insulin also significantly increases the activity of the mitochondrial proteins CPT-I, CPT-II and cytochrome oxidase with a coinciding increase the expression of CPT-II and cytochrome oxidase mRNA. The removal of serum increases the I$\sb{50}$ (concentration of inhibitor that halves enzyme activity) of CPT-I for malonyl-CoA by four-fold. Incubation with insulin returns I$\sb{50}$ values to serum levels. Incubation with insulin significantly increases malonyl-CoA and ATP levels in the cells with a resulting reduction in palmitate oxidation. Once malonyl-CoA inhibition of CPT-I is removed by permeabilizing the cells, insulin significantly increases the oxidation of palmitoyl-CoA in a manner which parallels the increase in CPT-I activity. Interestingly, CPT-II activity increases significantly only at the tissue culture concentration (1.7 $\mu$M) of insulin suggesting that the IGF-I pathway may be involved. Supporting a role for the IGF-I pathway in the insulin-induced increase in CPT activity is the significant increase in the synthesis of both cellular and mitochondrial proteins as well as increased synthesis of CPT-II. Consistent with an IGF-mediated pathway for the effect of insulin, IGF-I (10 ng/ml) significantly increases the activities of both CPT-I and -II. An IGF-I analogue which inhibits the autophosphorylation of the IGF-I receptor blunts the insulin-mediated increase in CPT-I and -II activity by greater than 70% and virtually eliminates the IGF-I response by greater than 90%. This is the first study to demonstrate the involvement of the IGF-I pathway in the regulation of mitochondrial protein expression, e.g. CPT. ^

Modulating bioreductive drug activity with antivascular agents

Modulation of tumor hypoxia to increase bioreductive drug antitumor activity was investigated. The antivascular agent 5,6-dimethylxanthenone acetic acid (DMXAA) was used in combination studies with the bioreductive drugs Tirapazamine (TPZ) and Mitomycin C (MMC). Blood perfusion studies with DMXAA showed a maximal reduction of 66% in tumor blood flow 4 hours post drug administration. This tumor specific decrease in perfusion was also found to be dose-dependent, with 25 and 30 mg/kg DMXAA yielding greater than 50% reduction in tumor blood flow. Increases in antitumor activity with combination therapy (bioreductive drugs $+$ DMXAA) were significant over individual therapies, suggesting an increased activity due to increased hypoxia induced by DMXAA. Combination studies yielded the following significant tumor growth delays over control: MMC (5mg/kg) $+$ DMXAA (25mg/kg) = 20 days, MMC (2.5mg/kg) $+$ DMXAA (25 mg/kg) = 8 days, TPZ (21.4mg/kg) $+$ DMXAA (17.5mg/kg) = 4 days. The mechanism of interaction of these drugs was investigated by measuring metabolite production and DNA damage. 'Real time' microdialysis studies indicated maximal metabolite production at 20-30 minutes post injection for individual and combination therapies. DNA double strand breaks induced by TPZ $\pm$ DMXAA (20 minutes post injection) were analyzed by pulsed field gel electrophoresis (PFGE). Southern blot analyses and quantification showed TPZ induced DNA double strand breaks, but this effect was not evident in combination studies with DMXAA. Based on these data, combination studies of TPZ $+$ DMXAA showed increased antitumor activity over individual drug therapies. The mechanism of this increased activity, however, does not appear to be due to an increase in TPZ bioreduction at this time point. ^

Structural studies of cytochrome P4501A1: Identification of substrate and cumene hydroperoxide binding regions in the active site of P4501A1 and characterization of the P4501A1 interaction with cytochrome P450 reductase

Cytochromes P450 are a superfamily of heme-thiolate proteins that function in a concert with another protein, cytochrome P450 reductase, as terminal oxidases of an enzymatic system catalyzing the metabolism of a variety of foreign compounds and endogenous substrates. In order to better understand P450s catalytic mechanism and substrate specificity, information about the structure of the active site is necessary. Given the lack of a crystal structure of mammalian P450, other methods have been used to elucidate the substrate recognition and binding site structure in the active center. In this project I utilized the photoaffinity labeling technique and site-directed mutagenesis approach to gain further structural insight into the active site of mammalian cytochrome P4501AI and examine the role of surface residues in the interaction of P4501A1 with the reductase. ^ Four crosslinked peptides were identified by photoaffinity labeling using diazido benzphetamine as a substrate analog. Alignment of the primary structure of cytochrome P4501A1 with that of bacterial cytochrome P450102 (the crystal structure of which is known) revealed that two of the isolated crosslinked peptides can be placed in the vicinity of heme (in the L helix region and β10-β11 sheet region of cytochrome P450102) and could be involved in substrate binding. The other two peptides were located on the surface of the protein with the label bound specifically to Lys residues that were proposed to be involved in reductase-P450 interaction. ^ Alternatively, it has been shown that some of the organic hydroperoxides can support P450 catalyzed reactions in the absence of NADPH, O2 and reductase. By means of photoaffinity labeling the cumene hydroperoxide binding region was identified. Using azidocumene as the photoaffinity label, the tripeptide T501-L502-K503 was shown to be the site where azidocumene covalently binds to P4501A1. The sequence alignment of cytochrome P4501A1 with cytochrome P450102 predicts that this region might correspond to β-sheet structure localized on the distal side of the heme ring near the I helix and the oxygen binding pocket. The role of Thr501 in the cumene hydroperoxide binding was confirmed by mutations of this residue and kinetic analysis of the effects of the mutations. ^ In addition, the role of two lysine residues, Lys271 and Lys279, in the interaction with reductase was examined by means of site-directed mutagenesis. The lysine residues were substituted with isoleucine and enzymatic activity of the wild type and the mutants were compared in reductase- and cumene hydroperoxide-supported systems. The lysine 279 residue has been shown to play a critical role in the P4501A1-reductase interaction. ^

Impact of Acetazolamide and CPAP on Cortical Activity in Obstructive Sleep Apnea Patients

STUDY OBJECTIVES 1) To investigate the impact of acetazolamide, a drug commonly prescribed for altitude sickness, on cortical oscillations in patients with obstructive sleep apnea syndrome (OSAS). 2) To examine alterations in the sleep EEG after short-term discontinuation of continuous positive airway pressure (CPAP) therapy. DESIGN Data from two double-blind, placebo-controlled randomized cross-over design studies were analyzed. SETTING Polysomnographic recordings in sleep laboratory at 490 m and at moderate altitudes in the Swiss Alps: 1630 or 1860 m and 2590 m. PATIENTS Study 1: 39 OSAS patients. Study 2: 41 OSAS patients. INTERVENTIONS Study 1: OSAS patients withdrawn from treatment with CPAP. Study 2: OSAS patients treated with autoCPAP. Treatment with acetazolamide (500-750 mg) or placebo at moderate altitudes. MEASUREMENTS AND RESULTS An evening dose of 500 mg acetazolamide reduced slow-wave activity (SWA; approximately 10%) and increased spindle activity (approximately 10%) during non-REM sleep. In addition, alpha activity during wake after lights out was increased. An evening dose of 250 mg did not affect these cortical oscillations. Discontinuation of CPAP therapy revealed a reduction in SWA (5-10%) and increase in beta activity (approximately 25%). CONCLUSIONS The higher evening dose of 500 mg acetazolamide showed the "spectral fingerprint" of Benzodiazepines, while 250 mg acetazolamide had no impact on cortical oscillations. However, both doses had beneficial effects on oxygen saturation and sleep quality.

Reduction in Northward Incursions of the South Asian Monsoon Since ~1400 AD Inferred from a Mt. Everest Ice Core

A highly resolved Mt. Everest ice core reveals a decrease in marine and increase in continental air masses related to relatively high summer surface pressure over Mongolia, and reduction in northward incursions of the summer South Asian monsoon since similar to 1400 AD. Previously published proxy records from lower sites south of the Himalayas indicate strengthening of the monsoon since this time. These regional differences are consistent with a south north seesaw in convective activity in the Asian monsoon region, and reflect a southward shift in the mean summer position of the monsoon trough since similar to 1400 AD. The change in monsoonal circulation at 1400 AD is synchronous with a reduction in solar irradiance and the onset of the LIA. This demonstrates a hemispheric scale circulation reorganization at this time, and the potential for future large shifts in monsoonal circulation.