julilili42/papers huggingface dataset:
Hyphenation of Capillary HPLC to Microcoil 1H NMR Spectroscopy for the Determination of Tocopherol Homologues
2004-03-27

Highly selective reversed phases (C(30) phases) are self-packed in 250 microm inner diameter fused-silica capillaries and employed for capillary HPLC separation of shape-constrained natural compounds (tocopherol homologues, vitamin E). Miniaturized hyphenated systems such as capillary HPLC-ESI-MS (positive ionization mode) and, with special emphasis, continuous-flow capillary HPLC- NMR are used for structural determination of the separated compounds. Despite the small amount of sample available (1.33 microg of each tocopherol), the authors have been able to monitor the capillary HPLC separation under continuous-flow (1)H NMR conditions, thus allowing an immediate peak identification. Further structural assignment was carried out in the stopped-flow NMR mode as shown, for example, by a 2D (1)H,(1)H COSY NMR spectrum of alpha-tocopherol. We demonstrate in this paper the considerable potential of hyphenated capillary separations coupled to MS and NMR for the investigation of restricted amounts of sample.
Organic Osmolyte Permeabilities of the Malaria-induced Anion Conductances in Human Erythrocytes
2004-03-29

Infection of human erythrocytes with the malaria parasite Plasmodium falciparum induces new permeability pathways (NPPs) in the host cell membrane. Isotopic flux measurements demonstrated that the NPP are permeable to a wide variety of molecules, thus allowing uptake of nutrients and release of waste products. Recent patch-clamp recordings demonstrated the infection-induced up-regulation of an inwardly and an outwardly rectifying Cl− conductance. The present experiments have been performed to explore the sensitivity to cell volume and the organic osmolyte permeability of the two conductances. It is shown that the outward rectifier has a high relative lactate permeability (Plactate/PCl = 0.4). Sucrose inhibited the outward-rectifier and abolished the infection-induced hemolysis in isosmotic sorbitol solution but had no or little effect on the inward-rectifier. Furosemide and NPPB blocked the outward-rectifying lactate current and the sorbitol hemolysis with IC50s in the range of 0.1 and 1 μM, respectively. In contrast, the IC50s of NPPB and furosemide for the inward-rectifying current were &amp;gt;10 μM. Osmotic cell-shrinkage inhibited the inwardly but not the outwardly rectifying conductance. In conclusion, the parasite-induced outwardly-rectifying anion conductance allows permeation of lactate and neutral carbohydrates, whereas the inward rectifier seems largely impermeable to organic solutes. All together, these data should help to resolve ongoing controversy regarding the number of unique channels that exist in P. falciparum–infected erythrocytes.
Cellular responses and cytokine production in post-treatment hookworm patients from an endemic area in Brazil
2004-03-30

SUMMARY Human hookworm infections are distributed widely in tropical areas and have a significant impact on host morbidity and human health. In the present study, we investigated the cellular responsiveness and cytokine production in peripheral blood mononuclear cells (PBMC) from Necator americanus-infected schoolchildren who had recently received chemotherapy, and compared them with non-infected endemic controls. Hookworm patients and treated, egg-negative individuals showed a lower cellular reactivity against phytohaemagglutinin (PHA) and hookworm antigen when compared with egg-negative endemic controls. The baseline production of proinflammatory tumour necrosis factor-α (TNF-α) in PBMC from infected patients and treated, egg-negative individuals was elevated. On the other hand, PHA- or hookworm antigen-induced interleukin (IL)-12 and interferon (IFN)-γ secretion was higher in endemic controls than in hookworm patients, who either continued egg-positive or were egg-negative after treatment. Also, PBMC from endemic controls secreted more IL-5 and IL-13 than the other patient groups. Opposite to that, the spontaneous as well as the antigen-driven IL-10 secretion was lower in endemic controls when compared with the other groups. In summary, patently hookworm-infected as well as egg-negative treated patients disclosed an elevated spontaneous cellular secretion of proinflammatory TNF-α, a prominent secretion of regulatory Th2-type IL-10 and an impaired production of IL-12, IFN-γ, IL-5 and IL-13.
How Efficient is a Simple Copying Task to Diagnose Spatial Neglect in its Chronic Phase?
2004-03-30

Twenty-five patients with spatial neglect were tested in the acute phase and about 1.3 years after a right-hemisphere stroke. Ten patients had developed chronic spatial neglect. We investigated how sensitive a simple copying task is in detecting spatial neglect in the chronic phase. When the stroke was acute, all 10 patients omitted a considerable number of contralesionally located items in the copying task. In the chronic phase, 60% of the chronic neglect patients still demonstrated noticeable neglect in the copying task. The data indicate that a simple task such as the copying of a multi-object scene is a helpful tool to detect residual symptoms of spatial neglect even more than 1 year after the stroke.
Mass Spectrometric Analysis of Surfactant Metabolism in Human Volunteers Using Deuteriated Choline
2004-03-30

Surfactant reduces surface tension at pulmonary air-liquid interfaces. Although its major component is dipalmitoyl-phosphatidylcholine (PC16:0/16:0), other PC species, principally palmitoylmyristoyl-PC, palmitoylpalmitoleoyl-PC, and palmitoyloleoyl-PC, are integral components of surfactant. The composition and metabolism of PC species depend on pulmonary development, respiratory rate, and pathologic alterations, which have largely been investigated in animals using radiolabeled precursors. Recent advances in mass spectrometry and availability of precursors carrying stable isotopes make metabolic experiments in human subjects ethically feasible. We introduce a technique to quantify surfactant PC synthesis in vivo using deuteriated choline coupled with electrospray ionization tandem mass spectrometry. Endogenous PC from induced sputa of healthy volunteers comprised 54.0 +/- 1.5% PC16:0/16:0, 9.7 +/- 0.7% palmitoylmyristoyl-PC, 10.0 +/- 1.0% palmitoylpalmitoleoyl-PC, and 13.1 +/- 0.3% palmitoyloleoyl-PC. Infusion of deuteriated choline chloride (3.6 mg/kg body weight) over 3 hours resulted in linear incorporation into PC over 30 hours. After a plateau of 0.61 +/- 0.04% labeled PC between 30 and 48 hours, incorporation decreased to 0.30 +/- 0.02% within 7 days. Compared with native PC, fractional label was initially lower for PC16:0/16:0 (31.9 +/- 8.3%) but was higher for palmitoyloleoyl-PC (21.0 +/- 1.2%), and equilibrium was achieved after only 48 hours. We conclude that infusion of deuteriated choline and electrospray ionization tandem mass spectrometry is useful to investigate surfactant metabolism in humans in vivo.
Staphylococcal NreB: an O2‐sensing histidine protein kinase with an O2‐labile iron–sulphur cluster of the FNR type
2004-03-30

Summary The nreABC ( n itrogen re gulation) operon encodes a new staphylococcal two‐component regulatory system that controls dissimilatory nitrate/nitrite reduction in response to oxygen. Unlike other two‐component sensors NreB is a cytosolic protein with four N‐terminal cysteine residues. It was shown that both the NreB–cysteine cluster and Fe ions are required for function. Isolated NreB was converted to the active form by incubation with cysteine desulphurase, ferrous ions and cysteine. This activation is typical for FeS‐containing proteins and was reversed by oxygen. During reconstitution an absorption band at 420 nm and a yellow‐brownish colour (typical for an FNR‐type iron–sulphur cluster formation) developed. After alkylation of thiol groups in NreB and in the cysteine mutant NreB(C62S) almost no iron–sulphur cluster was incorporated; both findings corroborated the importance of the cysteine residues. Comparison of the kinase activity of (i) the reconstituted (ii) the unreconstituted, and (iii) the unreconstituted and deferrated NreB–His indicated that NreB kinase activity depended on iron availability and was greatly enhanced by reconstitution. NreB is the first direct oxygen‐sensing protein described in staphylococci so far. Reconstituted NreB contains 4–8 acid‐labile Fe and sulphide ions per NreB which is in agreement with the presence of 1–2 iron–sulphur [4Fe‐4S] 2+ clusters of the FNR‐type. Unlike FNR, NreB does not act directly as transcriptional activator, but transfers the phosphoryl group to the response regulator NreC.
Regulation of intestinal phosphate cotransporter NaPi IIb by ubiquitin ligase Nedd4–2 and by serum- and glucocorticoid-dependent kinase 1
2004-03-30

Serum and glucocorticoid-inducible kinase 1 (SGK1) is highly expressed in enterocytes. The significance of the kinase in regulation of intestinal function has, however, remained elusive. In Xenopus laevis oocytes, SGK1 stimulates the epithelial Na + channel by phosphorylating the ubiquitin ligase Nedd4–2, which regulates channels by ubiquitination leading to subsequent degradation of the channel protein. Thus the present study has been performed to explore whether SGK1 regulates transport systems expressed in intestinal epithelial cells, specifically type IIb sodium-phosphate (Na + -P i ) cotransporter (NaPi IIb). Immunohistochemistry in human small intestine revealed SGK1 colocalization with Nedd4–2 in villus enterocytes. For functional analysis cRNA encoding NaPi IIb, the SGK isoforms and/or the Nedd4–2 were injected into X. laevis oocytes, and transport activity was quantified as the substrate-induced current ( I P ). Exposure to 3 mM phosphate induces an I P in NaPi IIb-expressing oocytes. Coinjection of Nedd4–2, but not the catalytically inactive mutant C938S Nedd4–2, significantly downregulates I P , whereas the coinjection of S422D SGK1 markedly stimulates I P and even fully reverses the effect of Nedd4–2 on I P . The effect of S422D SGK1 on NaPi IIb is mimicked by wild-type SGK3 but not by wild-type SGK2, constitutively active T308D,S473D PKB, or inactive K127N SGK1. Moreover, S422D SGK1 and SGK3 phosphorylate Nedd4–2. In conclusion, SGK1 stimulates the NaPi IIb, at least in part, by phosphorylating and thereby inhibiting Nedd4–2 binding to its target. Thus the present study reveals a novel signaling pathway in the regulation of intestinal phosphate transport, which may be important for regulation of phosphate balance.
Evidence for a role of protein kinase C-α in urine concentration
2004-03-30

In mouse kidney, the conventional protein kinase C (PKC) isoenzyme α is expressed in glomeruli, the cortical collecting duct (intercalated cells only), and medullary collecting duct. To get insights on its function, PKC-α knockout (−/−) and wild-type (+/+) mice were studied. When provided free access to water, PKC-α −/− mice showed ∼50% greater urine flow rate and lower urinary osmolality in 24-h metabolic cage experiments despite a greater urinary vasopressin-to-creatinine ratio vs. PKC-α +/+ mice. Renal albumin excretion was not different. Clearance experiments under inactin/ketamine anesthesia revealed a modestly reduced glomerular filtration rate and showed a reduced absolute and fractional renal fluid reabsorption in PKC-α −/− mice. The sodium-restricting response to a low-sodium diet was unaffected in PKC-α −/− mice. Urinary osmolality was reduced to similar hypotonic levels in PKC-α −/− and +/+ mice during acute oral water loading or application of the vasopressin V 2 -receptor antagonist SR-121463. In comparison, the lower urinary osmolality observed in PKC-α −/− mice vs. wild-type mice under basal conditions persisted during water restriction for 36 h. In conclusion, PKC-α appears not to play a major role in renal sodium reabsorption but, consistent with its expression in the medullary collecting duct, contributes to urinary concentration in mice. Considering that PKC-βI and -βII are coexpressed with PKC-α in mouse medullary collecting duct, the present results indicate that conventional PKC isoenzymes cannot fully compensate for each other.
Immunolocalization of protein kinase C isoenzymes α, βI, βII, δ, and ε in mouse kidney
2004-03-30

Localization of protein kinase C (PKC) isoenzymes α, βI, βII, δ, and ε was studied employing Western blot analysis and immunohistochemical methods including confocal laser-scanning microscopy in the kidney of two mice strains, namely, C57BL/6 and 129/Sv, which have recently been used as genetic backgrounds for respective knockout mice. Immunoblot analysis identified immunoreactive bands for each isoenzyme in total kidney cell extracts. Isoenzyme expression sites were identical for both strains. Glomeruli expressed PKC-α, -βI, and -ε. The latter isoenzme was also detected in apical aspects of proximal convoluted but not in proximal straight tubules. In contrast to rats, neither PKC-α nor PKC-βI was detectable in the proximal tubule. Immunofluorescence was observed in luminal membranes of medullary (MTAL) and cortical thick ascending limbs for PKC-βI and in MTAL for PKC-ε. The cortical collecting duct expressed PKC-α, -βI, and -δ in intercalated cells only. In the outer medullary collecting duct, PKC-α and -βI were detectable in principal cells, whereas PKC-δ was found in intercalated cells. In the inner medullary collecting duct, PKC-α, -βI, and -βII were detected. As described for the rat, the expression of PKC-βII was otherwise restricted to cortical and medullary interstitial cells. The specificity of all labeling was confirmed in respective PKC isoenzyme knockout mice. In summary, distinct expression patterns were shown for PKC isoenzymes α, βI, βII, δ, and ε in the mouse kidney.
A 63bp Deletion in the Promoter of RAGE Correlates with a Decreased Risk for Nephropathy in Patients with Type 2 Diabetes
2004-03-30

Several polymorphisms have been identified in the RAGE-promoter region that might modulate the outcome of disease. Here we analyse the association of a 63bp deletion (delta63) spanning from bp - 407 to bp - 345 with diabetic nephropathy. The deletion was determined using the polymerase chain reaction (PCR) in a cross-sectional study with 1087 patients with type 1 diabetes (n = 559) and type 2 diabetes (n = 528). 475 patients with osteoporosis served as disease independent control. The prevalence of the heterozygous genotype did not significantly differ between the three groups (type 1: 2.15 %, type 2: 2.27 %, controls: 1.47 %), indicating that heterozygous delta63 is not related to the manifestation of diabetes. Homozygous carriers were not identified in this study. The heterozygous delta63 genotype, was associated with a reduced prevalence of diabetic nephropathy in patients with type 2 diabetes (OR = 0.06; 95 % CI: [0.05, 0.07]), but not in patients with type 1 (OR = 1.49; 95 % CI: [1.14, 1.94]). We conclude, that patients with type 2 diabetes and the 63bp deletion in the promoter of RAGE seem to be protected from diabetic nephropathy. The observed difference between type 1 and type 2 diabetes might point to diverse pathomechanisms of nephropathy in both types of diabetes.
Parasite‐specific antibody and cytokine profiles in newborns from Plasmodium falciparum and Entamoeba histolytica/ dispar‐infected mothers
2004-03-30

Passage of parasites and their antigens across the placenta occurs with metazoan as well as protozoan parasites, and this study addressed to which extent exposure to and infection of mothers with Plasmodium spp. and Entamoeba histolytica/dispar has sensitized their offspring for parasite‐specific immune responses. While at delivery none of the mothers presented with an acute malaria attack, 42% were seropositive for P. falciparum . In half of the mothers cysts of E. histolytica/dispar were detected in stool specimen, 51% of them were found seropositive for E. histolytica , and E. histolytica ‐specific immunoglobulin A (IgA) responses were detected in neonates of seropositive mothers as well. Umbilical cord blood cells (UCBC) from neonates, when activated with the mitogen phytohaemagglutinine (PHA) and bacterial streptolysin O (SL‐O), released significantly less interferon (IFN)‐ γ , interleukin (IL)‐10 and tumor necrosis factor (TNF)‐ α into cell culture supernatants than peripheral blood cells (PBMC) of mothers. In response to Plasmodium ‐ and Entamoeba ‐specific antigens UCBC and PBMC produced equal amounts of IL‐1 β , TNF‐ α , IFN‐ γ and IL‐5, but PBMC from mothers secreted significantly more IL‐10. Parasite‐specific production of inflammatory and Th 1 ‐ and Th 2 ‐type cytokines was similar in newborns of Plasmodium and Entamoeba seropositive and seronegative mothers. In summary, repeated exposure and subclinical infection of mothers with E. histolytica or P. falciparum will suffice to prime in utero their children for inflammatory and both Th 1 ‐ and Th 2 ‐type cytokine responses, and such broad and mixed cytokine spectrum may be of advantage upon secondary parasite challenge in later life.
On-line event detection by recursive Dynamic Principal Component Analysis and gas sensor arrays under drift conditions
2004-03-30

Leakage detection is an important issue in many chemical sensing applications. Leakage detection hy thresholds suffers from impor-tant drawbacks when sensors have serious drifts or they are af-fected by cross-sensitivities. Here we present an adaptive method based in a Dynamic Principal Component Analysis that models the relationships between the sensors in the may. In normal con-ditions a certain variance distribution characterizes sensor signals. However, in the presence of a new source of variance the PCA decomposition changes drastically. In order to prevent the influ-ence of sensor drifts the model is adaptive and it is calculated in a recursive manner with minimum computational effort. The behav-ior of this technique is studied with synthetic signals and with real signals arising by oil vapor leakages in an air compressor. Results clearly demonstrate the efficiency of the proposed method.
A Chemically Modified Platinum Electrode as a Bidentate Diamine Ligand for Forming Well‐Defined, Immobilized Bis(η1‐P‐ether phosphane)(diamine)ruthenium(II) Complexes
2004-03-30

Ligands with potential: Hydrogenation catalysts similar to Noyori's complexes are assembled on the surface of a chemically modified platinum electrode, and the immobilized organometallic species are characterized by cyclic voltammetry, revealing a chelate-type structure. The organometallic compound is bound by a single chain to the modified platinum surface (see picture).
Triggering Receptor Expressed on Myeloid Cells-1 in Neutrophil Inflammatory Responses: Differential Regulation of Activation and Survival
2004-04-01

Abstract Polymorphonuclear neutrophils (PMN) are crucial in the innate host defense by their ability to rapidly accumulate in inflamed tissues and clear a site of infection from microbial pathogens by their potent effector mechanisms. The triggering receptor expressed on myeloid cells (TREM)-1 is a recently described activating receptor on PMN with an important role in inflammation. However, the effects of TREM-1 stimulation on a cellular level remain to be further defined. To characterize TREM-1-mediated activation of human PMN, we evaluated the effect of receptor ligation on PMN effector functions. Activation via TREM-1 induces immediate degranulation of neutrophilic granules resulting in the release of IL-8, respiratory burst, and phagocytosis. TREM-1 ligation synergizes with the activation by the Toll-like receptors (TLR) ligands LPS, Pam3Cys, and R-848. In contrast, no synergy between TREM-1- and TLR-mediated stimulation was observed concerning PMN survival, whereas TLR-mediated stimuli protect PMN from apoptosis, concurrent TREM-1 activation neutralizes these anti-apoptotic effects. These results give a new perspective for the regulation of neutrophil inflammatory responses emphasizing the importance of TREM-1 in innate immunity.
Aspergillus fumigatus antigens activate innate immune cells via toll‐like receptors 2 and 4
2004-04-01

Summary Invasive aspergillosis (IA) is a leading cause of mortality in haematological patients. Appropriate activation of the innate immune system is crucial for the successful clearance of IA. Therefore, we studied the Aspergillus fumigatus ‐mediated activation of human granulocytes and monocyte‐derived immature dendritic cells (DCs), as well as murine bone marrow‐derived DCs (BMDCs) from wild type, toll‐like receptor (TLR)4‐deficient, TLR2 knockout, and TLR2/TLR4 double deficient mice. Aspergillus fumigatus antigens induced the activation and maturation of immature DCs as characterized by CD83 expression, upregulation of major histocompatibility complex and co‐stimulatory molecules. Moreover, fungal antigens enhanced the phagocytosis and production of interleukin (IL)‐8 in granulocytes. The release of IL‐12 by BMDCs in response to A. fumigatus antigens was dependent on the expression of TLR2, whereas the release of IL‐6 was dependent on the expression of functional TLR4 molecules. The protein precipitate of A. fumigatus supernatant provided strong stimulation of DCs and granulocytes, indicating that a factor secreted by A. fumigatus might activate innate immune cells. In conclusion, A. fumigatus antigens induced the activation of DCs and granulocytes. Our results indicated that this activation was mediated via TLR2 and TLR4. Future studies are needed to assess the clinical impact of these findings in patients at high risk for IA.
Mechanisms and Time Course of Neuronal Degeneration in Experimental Autoimmune Encephalomyelitis
2004-04-01

Neuronal and axonal damage is considered to be the main cause for long‐term disability in multiple sclerosis. We analyzed the mechanisms and kinetics of neuronal cell death in experimental autoimmune encephalomyelitis (EAE) induced by myelin oligodendrocyte glycoprotein (MOG) by combining an electrophysiological in vivo assessment of the optic pathway with the investigation of retinal ganglion cell (RGC) counts. In accordance with our previous findings in this animal model, neuritis of the optic nerve (ON) leads to apoptotic RGC death. By further investigating the time course of RGC apoptosls in the present study, we found that neuronal cell death together with decreased visual acuity values occurred before the onset of clinical symptoms. Simultaneously with the time course of RGC apoptosis, we found a down‐regulation of phospho‐Akt as well as a shift in the relation of 2 proteins of the Bcl‐2 family, Bax and Bcl‐2, towards a more proapoptotic ratio in these cells. Comparing the kinetics and mechanisms of RGC death during MOG‐EAE with those following complete surgical transection of the ON, we found significant agreement. We hypothesize that the main reason for RGC loss in MOG‐EAE is the inflammatory attack but RGC death also occurs independently of histopathological ON changes.