julilili42/papers huggingface dataset:
Role of Charge Properties of Bacterial Envelope in Bactericidal Action of Human Group IIA Phospholipase A2against Staphylococcus aureus
2002-11-28

Mammalian Group IIA phospholipases A(2) (PLA(2)) potently kill Staphylococcus aureus. Highly cationic properties of these PLA(2) are important for Ca(2+)-independent binding and cell wall penetration, prerequisites for Ca(2+)-dependent degradation of membrane phospholipids and bacterial killing. To further delineate charge properties of the bacterial envelope important in Group IIA PLA(2) action against S. aureus, we examined the effects of mutations that prevent specific modifications of cell wall (dltA) and cell membrane (mprF) polyanions. In comparison to the parent strain, isogenic dltA(-) bacteria are approximately 30-100x more sensitive to PLA(2), whereas mprF(-) bacteria are <3-fold more sensitive. Differences in PLA(2) sensitivity of intact bacteria reflect differences in cell wall, not cell membrane, properties since protoplasts from all three strains are equally sensitive to PLA(2). A diminished positive charge in PLA(2) reduces PLA(2) binding and antibacterial activity. In contrast, diminished cell wall negative charge by substitution of (lipo)teichoic acids with d-alanine reduces antibacterial activity of bound PLA(2), but not initial PLA(2) binding. Therefore, the potent antistaphylococcal activity of Group IIA PLA(2) depends on cationic properties of the enzyme that promote binding to the cell wall, and polyanionic properties of cell wall (lipo)teichoic acids that promote attack of membrane phospholipids by bound PLA(2).
Evidence for shared recognition of a peptide ligand by a diverse panel of non-obese diabetic mice-derived, islet-specific, diabetogenic T cell clones
2002-11-28

MHC class II-restricted autoreactive T cells play a major role in the development of autoimmune diabetes mellitus in both human and mouse. Two of our groups previously established panels of islet-reactive CD4+ T cell clones from prediabetic non-obese diabetic (NOD) mice. These clones express distinct sets of TCR V alpha , V beta , J alpha and J beta , and also differ in the structure of the junctional region of TCR. All of the T cell clones have been shown to cause insulitis and several induce diabetes when transferred to various recipients. The antigen specificities of these T cell clones have not been determined, but they do not react with defined islet cell antigens such as glutamic acid decarboxylase. To identify the peptide ligands recognized by these clones, we examined the reactivity of the T cell clones to peptide mixtures in which anchor residues for H2-A g7 were fixed. Most of the clones showed similar reactivity to the peptide mixtures. To further determine the peptide ligands of the T cell clones, we synthesized several peptides based on the favored amino acid motifs and examined clone reactivity to the synthetic peptides. Some of the peptides, e.g. HLAI-RM and HIPI-RM, could stimulate most of the T cell clones tested, even though the clones expressed different TCR. The results suggest that our islet-reactive T cell clones recognize in islet beta cells a natural ligand that is similar to these peptides.
An Arabidopsis thaliana knock‐out mutant of the chloroplast triose phosphate/phosphate translocator is severely compromised only when starch synthesis, but not starch mobilisation is abolished
2002-12-01

Summary The Arabidopsis thaliana tpt‐1 mutant which is defective in the chloroplast triose phosphate/phosphate translocator (TPT) was isolated by reverse genetics. It contains a T‐DNA insertion 24 bp upstream of the start ATG of the TPT gene. The mutant lacks TPT transcripts and triose phosphate (TP)‐specific transport activities are reduced to below 5% of the wild type. Analyses of diurnal variations in the contents of starch, soluble sugars and phosphorylated intermediates combined with 14 CO 2 labelling studies showed, that the lack of TP export for cytosolic sucrose biosynthesis was almost fully compensated by both continuous accelerated starch turnover and export of neutral sugars from the stroma throughout the day. The utilisation of glucose 6‐phosphate (generated from exported glucose) rather than TP for sucrose biosynthesis in the light bypasses the key regulatory step catalysed by cytosolic fructose 1,6‐bisphosphatase. Despite its regulatory role in the feed‐forward control of sucrose biosynthesis, variations in the fructose 2,6‐bisphosphate content upon illumination were similar in the mutant and the wild type. Crosses of tpt‐1 with mutants unable to mobilise starch ( sex1 ) or to synthesise starch ( adg1‐1 ) revealed that growth and photosynthesis of the double mutants was severely impaired only when starch biosynthesis, but not its mobilisation, was affected. For tpt‐1 / sex1 combining a lack in the TPT with a deficiency in starch mobilisation, an additional compensatory mechanism emerged, i.e. the formation and (most likely) fast turnover of high molecular weight polysaccharides. Steady‐state RNA levels and transport activities of other phosphate translocators capable of transporting TP remained unaffected in the mutants.
Activation of Tubular Epithelial Cells in Diabetic Nephropathy
2002-12-01

Previous studies have shown that renal function in type 2 diabetes correlates better with tubular changes than with glomerular pathology. Since advanced glycation end products (AGEs; AGE-albumin) and in particular carboxymethyllysine (CML) are known to play a central role in diabetic nephropathy, we studied the activation of nuclear factor κB (NF-κB) in tubular epithelial cells in vivo and in vitro by AGE-albumin and CML. Urine samples from healthy control subjects (n = 50) and type 2 diabetic patients (n = 100) were collected and tested for excretion of CML and the presence of proximal tubular epithelial cells (pTECs). CML excretion was significantly higher in diabetic patients than in healthy control subjects (P &amp;lt; 0.0001) and correlated with the degree of albuminuria (r = 0.7, P &amp;lt; 0.0001), while there was no correlation between CML excretion and HbA1c (r = 0.03, P = 0.76). Urine sediments from 20 of 100 patients contained pTECs, evidenced by cytokeratin 18 positivity, while healthy control subjects (n = 50) showed none (P &amp;lt; 0.0001). Activated NF-κB could be detected in the nuclear region of excreted pTECs in 8 of 20 patients with pTECs in the urine sediment (40%). Five of eight NF-κBp65 antigen-positive cells stained positive for interleukin-6 (IL-6) antigen (62%), while only one of the NF-κB-negative cells showed IL-6 positivity. pTECs in the urine sediment correlated positively with albuminuria (r = 0.57, P &amp;lt; 0.0001) and CML excretion (r = 0.55, P &amp;lt; 0.0001). Immunohistochemistry in diabetic rat kidneys and a human diabetic kidney confirmed strong expression of NF-κB in tubular cells. To further prove an AGE/CML-induced NF-κB activation in pTECs, NF-κB activation was studied in cultured human pTECs by electrophoretic mobility shift assays (EMSAs) and Western blot. Stimulation of NF-κB binding activity was dose dependent and was one-half maximal at 250 nmol/l AGE-albumin or CML and time dependent at a maximum of activation after 4 days. Functional relevance of the observed NF-κB activation was demonstrated in pTECs transfected with a NF-κB-driven luciferase reporter plasmid and was associated with an increased release of IL-6 into the supernatant. The AGE- and CML-dependent activation of NF-κBp65 and NF-κB-dependent IL-6 expression could be inhibited using the soluble form of the receptor for AGEs (RAGE) (soluble RAGE [sRAGE]), RAGE-specific antibody, or the antioxidant thioctic acid. In addition transcriptional activity and IL-6 release from transfected cells could be inhibited by overexpression of the NF-κB-specific inhibitor κBα. The findings that excreted pTECs demonstrate activated NF-κB and IL-6 antigen and that AGE-albumin and CML lead to a perpetuated activation of NF-κB in vitro infer that a perpetuated increase in proinflammtory gene products, such as IL-6, plays a role in damaging the renal tubule.
Molecular cloning and sequence analysis of the clorobiocin biosynthetic gene cluster: new insights into the biosynthesis of aminocoumarin antibiotics The GenBank accession number for the sequence of cosmid K1F2 is AF329398.
2002-12-01

The biosynthetic gene cluster of the aminocoumarin antibiotic clorobiocin was cloned by screening of a cosmid library of Streptomyces roseochromogenes DS 12.976 with two heterologous probes from the novobiocin biosynthetic gene cluster. Sequence analysis revealed 27 ORFs with striking similarity to the biosynthetic gene clusters of novobiocin and coumermycin A(1). Inactivation of a putative aldolase gene, cloR, by in-frame deletion led to the abolishment of the production of clorobiocin. Feeding of the mutant with 3-dimethylallyl-4-hydroxybenzoic acid (Ring A of clorobiocin) restored clorobiocin production. Here, it is suggested that the formation of Ring A of clorobiocin may proceed via a retro-aldol reaction catalysed by CloR, i.e. by a mechanism different from the previously elucidated benzoic acid biosynthetic pathway in Streptomyces maritimus. A comparison of the gene clusters for clorobiocin, novobiocin and coumermycin A(1) showed that the structural differences between the three antibiotics were reflected remarkably well by differences in the organization of their respective biosynthetic gene clusters.
Preoperative magnetic source imaging for brain tumor surgery: a quantitative comparison with intraoperative sensory and motor mapping
2002-12-01

Object. The aim of this study was to compare quantitatively the methods of preoperative magnetic source (MS) imaging and intraoperative electrophysiological cortical mapping (ECM) in the localization of sensorimotor cortex in patients with intraaxial brain tumors. Methods. Preoperative magnetoencephalography (MEG) was performed while patients received painless tactile somatosensory stimulation of the lip, hand, and foot. The early somatosensory evoked field was modeled using a single equivalent current dipole approach to estimate the spatial source of the response. Three-dimensional magnetic resonance image volume data sets with fiducials were coregistered with the MEG recordings to form the MS image. These individualized functional brain maps were integrated into a neuronavigation system. Intraoperative mapping of somatosensory and/or motor cortex was performed and sites were compared. In two subgroups of patients we compared intraoperative somatosensory and motor stimulation sites with MS imaging—based somatosensory localizations. Mediolateral projection of the MS imaging source localizations to the cortical surface reduced systematic intermodality discrepancies. The distance between two corresponding points determined using MS imaging and ECM was 12.5 ± 1.3 mm for somatosensory—somatosensory and 19 ± 1.3 mm for somatosensory—motor comparisons. The observed 6.5 mm increase in site separation was systematically demonstrated in the anteroposterior direction, as expected from actual anatomy. In fact, intraoperative sites at which stimulation evoked the same patient response exhibited a spatial variation of 10.7 ± 0.7 mm. Conclusions. Preoperative MS imaging and intraoperative ECM show a favorable degree of quantitative correlation. Thus, MS imaging can be considered a valuable and accurate planning adjunct in the treatment of patients with intraaxial brain tumors.
Pharmacokinetic modelling of morphine, morphine-3-glucuronide and morphine-6-glucuronide in plasma and cerebrospinal fluid of neurosurgical patients after short-term infusion of morphine
2002-12-01

From the population pharmacokinetic model presented, CSF concentration profiles can be derived for M, M3G and M6G on the basis of dosing information and creatinine clearance without collecting CSF samples. Such profiles may then serve as the link between dose regimen and effect measurements in future clinical effect studies.
Screening for biologically active metabolites with endosymbiotic bacilli isolated from arthropods
2002-12-01

Endosymbiotic bacteria from the genus Bacillus were isolated from different compartments of the gut of various members of insects (Hexapoda) and millipedes (Diplopoda). They were grown in submerged culture and investigated by biological assays and HPLC-diode array analysis regarding their production of bioactive metabolites, which were isolated and determined in structure. Known compounds and yet unknown derivatives from the primary metabolism were detected, as well as antibacterially and antifungally acting peptide antibiotics.
The Role of the Oculomotor Vermis in the Control of Saccadic Eye Movements
2002-12-01

A bstract : The oculomotor vermis is a part of the posterior cerebellum, characterized by a low threshold (&lt;10 μA) for evoked saccades. It comprises vermal lobuli VIc and VIIA. Many Purkinje cells in this area show eye position or saccade‐related responses or combinations of the two and usually lack responses to the presentation of visual targets, guiding the oculomotor behavior. The saccade‐related responses are directionally selective and show preferences for saccade amplitude or duration, which differ widely between cells. However, at the population level, these saccade‐related Purkinje cells give a very precise account of the timing of the saccadic eye movement and, specifically, of the time it ends. This population signal might therefore contribute to determining the end of the saccadic eye movement. Furthermore, by changing the duration of the population response, the amplitude of the saccade could be changed. In other words, saccadic adaptation could be a consequence of changing a representation of time in the cerebellum.
Embryo and Endosperm Development Is Disrupted in the Female Gametophytic capulet Mutants of Arabidopsis
2002-12-01

Abstract The female gametophyte of higher plants gives rise, by double fertilization, to the diploid embryo and triploid endosperm, which develop in concert to produce the mature seed. What roles gametophytic maternal factors play in this process is not clear. The female-gametophytic effects on embryo and endosperm development in the Arabidopsis mea, fis, and fie mutants appear to be due to gametic imprinting that can be suppressed by METHYL TRANSFERASE1 antisense (MET1 a/s) transgene expression or by mutation of the DECREASE IN DNA METHYLATION1 (DDM1) gene. Here we describe two novel gametophytic maternal-effect mutants, capulet1 (cap1) and capulet2 (cap2). In the cap1 mutant, both embryo and endosperm development are arrested at early stages. In the cap2 mutant, endosperm development is blocked at very early stages, whereas embryos can develop to the early heart stage. The cap mutant phenotypes were not rescued by wild-type pollen nor by pollen from tetraploid plants. Furthermore, removal of silencing barriers from the paternal genome by MET1 a/s transgene expression or by the ddm1 mutation also failed to restore seed development in the cap mutants. Neither cap1 nor cap2 displayed autonomous seed development, in contrast to mea, fis, and fie mutants. In addition, cap2 was epistatic to fis1 in both autonomous endosperm and sexual development. Finally, both cap1 and cap2 mutant endosperms, like wild-type endosperms, expressed the paternally inactive endosperm-specific FIS2 promoter GUS fusion transgene only when the transgene was introduced via the embryo sac, indicating that imprinting was not affected. Our results suggest that the CAP genes represent novel maternal functions supplied by the female gametophyte that are required for embryo and endosperm development.
Antitubercular Isoniazid and Drug Resistance of Mycobacterium tuberculosis — A Review
2002-12-01

Abstract Isoniazid is one of the most potent drugs available for tuberculosis treatment. As a pro‐drug it requires activation, which is performed by catalase/peroxidase. The active principle, whose identity has not yet been determined unambiguously, then acts on at least one target molecule, the enoyl‐acyl carrier protein, required for the synthesis of the vital mycolic acids present in the cell wall of the bacterium. Some other targets have been proposed in order to explain the unusual potency of isoniazid; however, the supporting data are still controversial. We thoroughly discuss the action of isoniazid, resistance mechanisms, and the possible active product, which includes an isonicotinic acid‐NADH adduct as well as a meta ‐isomer of NADH. Both structures have been probed positively in a 3D modeling analysis.
Recent progress in enantiomeric separation by capillary electrochromatography
2002-12-01

Abstract Recent progress in enantiomeric separations by capillary electrochromatography (CEC) is reviewed. The development of simple and robust CEC column technologies plays an important role for popularization of CEC. During the last several years, various approaches for the preparation of enantioselective columns have been reported. Currently, the monolithic column technology (continuous beds) represents the most advanced approach for the preparation of CEC columns. The development of new chiral stationary phase used for CEC is another important issue in this field. Fundamental investigations on electrochromatographic behaviors of various CSPs are necessary in order to understand the separation mechanism and thus improve the separation performance. Some chiral stationary phases performed better under nonaqueous CEC conditions than reversed‐phase conditions. Coupling CEC with mass spectrometry (MS) provides a powerful tool for enantiomeric separation. Finally, some applications of enantiomeric separation by CEC are summarized.
Inflammatory stimuli recruit cathepsin activity to late endosomal compartments in human dendritic cells
2002-12-01

Proteolysis by endocytic cysteine proteases is a central element of the antigen-presentation machinery in dendritic cells (DC). It controls the generation of immunogenic peptides, guides the transit of both MHC class II and MHC-like molecules through the endocytic compartment and converts class II into a peptide-receptive state - features closely linked to DC maturation. Differential activity of endocytic proteases, in particular cathepsins, in subcellular compartments has been implicated as a key regulatory element in controlling this machinery in murine DC. We analyzed the expression and subcellular distribution of the major endocytic cysteine proteases (cathepsins S, B, L and H) along with their major endogenous inhibitor, Cystatin C, in resting and stimulated human DC. Although the majority of cathepsin activity was restricted to lysosomes in resting DC, cathepsins selectively accumulated in late endosomes after LPS-induced stimulation. Surprisingly, expression and distribution of Cystatin C was unaffected by DC maturation. Thus, late endosomes represent a specialized compartment where proteolytic activity is developmentally regulated in DC. This could facilitate the conversion of exogenous protein into MHC class II-peptide complexes.
Sequential genotyping ofPseudomonas aeruginosafrom upper and lower airways of cystic fibrosis patients
2002-12-01

A controversy exists concerning the adequate specimen to characterise colonisation of cystic fibrosis (CF) airways by Pseudomonas aeruginosa . Oropharyngeal, sputum and bronchoalveolar lavage samples were evaluated from 38 stable CF patients for the detection of P. aeruginosa , genetically different isolates within the same host and longitudinal variations in the genotype during repeated examinations. Bacterial isolates were typed by pulsed-field gel electrophoresis of deoxyribonucleic acid macrorestriction fragments. Sensitivity, negative and positive predictive values and specificity to detect P. aeruginosa were 35.7, 73.5, 83.3 and 96.2% for oropharyngeal cultures in nonexpectorating patients and 91.7, 94.1, 100 and 100% for sputum cultures from expectorating patients, respectively. Genotypes of Pseudomonas isolates recovered from oropharyngeal swabs and sputum differed to the strains recovered by bronchoscopy in 55% and 40%, respectively. In 62% longitudinal variations in the genotype occurred. One-half of these alterations were detectable by bronchoscopy only. In conclusion, sputum samples were of equal value as specimens from bronchoalveolar lavage to detect Pseudomonas aeruginosa colonisation. Cultures from the oropharynx are not suitable for characterising bacterial conditions in the cystic fibrosis lung. Different genotypes within the same host and longitudinal genetic alterations are common and may be detectable in the bronchoalveolar lavage fluid exclusively.
Ex Vivo and In Vitro Identification of a Consensus Promoter for VSG Genes Expressed by Metacyclic-Stage Trypanosomes in the Tsetse Fly
2002-12-01

ABSTRACT The trypanosome variant surface glycoprotein (VSG) is first expressed during differentiation to the infective, metacyclic population in tsetse fly salivary glands. Unlike the VSG genes expressed by bloodstream form trypanosomes, metacyclic VSG s ( MVSG s) have their own promoters. The scarcity of metacyclic cells has meant that only indirect approaches have been used to study these promoters, and not even their identities have been agreed on. Here, we isolated trypanosomes by dissection from salivary glands and used an approach involving 5′ rapid amplification of cDNA ends to identify the transcription start site of three MVSG s. This shows that the authentic start site is that proposed for the MVAT series of MVSG s (K. S. Kim and J. E. Donelson, J. Biol. Chem. 272: 24637-24645, 1997). In the more readily accessible procyclic trypanosome stage, where MVSG s are normally silent, we used reporter gene assays and linker scanning analysis to confirm that the 67 bp upstream of the start site is a promoter. This is confirmed further by accurate initiation in a homologous in vitro transcription system. We show also that MVSG promoters become derepressed when tested outwith their endogenous, subtelomeric loci. The MVSG promoters are only loosely conserved with bloodstream VSG promoters, and our detailed analysis of the 1.63 MVSG promoter reveals that its activity depends on the start site itself and sequences 26 to 49 bp and 56 to 60 bp upstream. These are longer than those necessary for the bloodstream promoter.
β3-Adrenergic regulation of an ion channel in the heart—inhibition of the slow delayed rectifier potassium current IKs in guinea pig ventricular myocytes
2002-12-01

We have demonstrated a functional coupling between the beta(3)-adrenoceptor and ion channel function in the mammalian heart. Our findings point to a potential role for beta(3)-adrenoceptors in cardiac electrophysiology and pathophysiology.
Allergic cholestatic hepatitis and exanthema induced by metamizole: verification by lymphocyte transformation test
2002-12-01

Abstract: We report about a 66‐year‐old‐male patient who was hospitalized with generalized exanthema and increase of liver enzymes after intake of metamizole because of flue‐like symptoms. Despite initial high dose steroids, disease activity persisted, and therefore liver biopsy was performed. Histology revealed acute hepatitis with perivenular non‐bridging confluent necrosis and granuloma formation consistent with drug‐induced hepatitis. A metamizole‐induced process was suspected. Lymphocyte transformation test confirmed the sensitization of the patient's lymphocytes to metamizole and three of its four metabolites (4‐methylaminoantipyrine, 4‐acetylaminoantipyrine and 4‐formylaminoantipyrine). Other drugs could be excluded with high probability. In the follow‐up, the general condition of the patient improved, and liver enzymes decreased under treatment with steroids. Thus, we conclude that in this patient metamizole has induced an allergic reaction not only of the skin but also of the liver. To our knowledge, an allergic cholestatic hepatitis caused by metamizole has been reported only once in literature.