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At least 793 records · Page 44Linked to original sources

PubMed2006

Human SGT interacts with Bag-6/Bat-3/Scythe and cells with reduced levels of either protein display persistence of few misaligned chromosomes and mitotic arrest.

The human small glutamine-rich TPR-containing protein (hSGT) is essential for cell division since RNA-interference-mediated strong reduction of hSGT protein levels causes mitotic arrest (M. Winnefeld, J. Rommelaere, and C. Cziepluch, The human small glutamine-rich TPR-containing protein is required for progress through cell division, Exp. Cell Res. 293 (2004), 43-57). Analysis of HeLa cells expressing a histone 2A-YFP fusion protein revealed the continuous presence of few mislocalized chromosomes close to the spindle poles as possible cause for hSGT depletion-dependent prometaphase arrest. Cells unable to rescue these mislocalized chromosomes into the metaphase plate died at this stage through apoptosis. In order to address hSGT function at the molecular level, mass spectrometry analysis of proteins which co-immunoprecipitated with Flag-tagged hSGT was performed. Thereby, Hsp70 and Bag-6/Bat-3/Scythe were identified as novel hSGT interaction partners while interaction with Hsc70 was confirmed. Results obtained with truncated versions of the hSGT protein revealed that Bag-6/Bat-3/Scythe and Hsp70 or Hsc70 were independently able to form complexes with hSGT. Interaction of hSGT with Hsc70, Hsp70 or Bag-6/Bat-3/Scythe was demonstrated in prometaphase, thereby suggesting a possible role for complexes containing hSGT and distinct (co)-chaperones during mitosis. Finally, cells from populations with reduced levels of Bag-6/Bat-3/Scythe also displayed persistence of mislocalized chromosomes and mitotic arrest, which strongly indicated that hSGT-Bag-6/Bat-3/Scythe complexes could be directly or indirectly required for complete chromosome congression.

Apoptosis↗

PubMed2002

Drosophila crooked-neck protein co-fractionates in a multiprotein complex with splicing factors.

The Drosophila crooked neck (crn) gene encodes an unusual TPR-containing protein whose function is essential for embryonic development. Homology with other TPR-proteins involved in cell cycle control, initially led to the proposal that Crn might play a critical role in regulation of embryonic cell divisions. Here, we show that Crn does not have a cell cycle function in the embryo. By using specific antibodies we also show that the Crn protein is a nuclear protein which localizes in "speckles" which could correspond to preferential localization of several other splicing factors. Fractionation of nuclear extracts on sucrose gradients revealed Crn in a 900 kDa multiproteic complex together with snRNPs, suggesting that Crn participates in the assembly of the splicing machinery in vivo.

Animals↗

PubMed2003

Activation of brainstem catecholaminergic neurons during voluntary diving in rats.

Underwater submergence produces a complex autonomic response that includes apnea, a parasympathetically-mediated bradycardia, and a sympathetically-mediated increase in total peripheral resistance (TPR). The present study was designed to identify brainstem catecholaminergic neurons that may be involved in producing the increased TPR during underwater submergence. Twelve male Sprague-Dawley rats were trained to voluntarily dive 5 m through an underwater maze. On the day of the experiment the rats were randomly separated into a Diving group that repetitively dived underwater, a Swimming group that repetitively swam on the surface of the water, and a Control group that remained in their cages. After the experiment the brainstems of the rats were immunohistologically processed for Fos as an indicator of neuronal activation, and for tyrosine hydroxylase (TH) as an indentifier of catecholaminergic neurons. Neurons labeled with both Fos and TH identified activated catecholaminergic neurons. In Diving rats there was increased Fos+TH labeling in A1, C1, A2, A5, and sub-coeruleus, as well as globosa neurons in the lateral A7 region compared with Control rats, and in A1, C1 and A5 compared with Swimming rats. In Swimming rats Fos+TH labeling was significantly increased in caudal A1, A5, sub-coeruleus and globosa neurons compared with Control rats. These data suggest that selective groups of catecholaminergic neurons within the brainstem are activated by voluntary underwater submergence, and some probably contribute to the sympathetically-mediated increase in vascular tone during diving.

Animals↗

PubMed1997

Haemodynamic and endocrine effects of type 1 angiotensin II receptor blockade in patients with hypoxaemic cor pulmonale.

OBJECTIVES: Angiotensin II (ANG II) is known to be a potent vasoconstrictor agent in the pulmonary circulation. Furthermore, type 1 ANG II receptor blockade with losartan attenuates acute hypoxic pulmonary vasoconstriction in normal subjects. The aim of this study was therefore to evaluate the haemodynamic and endocrine sequelae of type 1 ANG II receptor blockade in patients with hypoxaemic cor pulmonale. METHODS: Nine patients with chronic obstructive pulmonary disease (COPD) age 67 +/- 3 years with pulmonary hypertension and normal left ventricular systolic function were studied on two separate occasions in a double-blind, placebo-controlled, crossover study. They were randomised to receive either 50 mg of oral losartan or matched placebo. Pulsed wave Doppler echocardiography was used to measure cardiac output (CO), mean pulmonary artery pressure (MPAP) and hence systemic vascular resistance (SVR) and total pulmonary vascular resistance (TPR). Haemodynamic measurements and venous blood samples were taken at baseline and after 2 and 4 h. RESULTS: Maximal effects were observed at 4 h where losartan compared to placebo resulted in a significant reduction in both MPAP (28.6 +/- 2.0 vs 32.4 +/- 1.5 mmHg) and TPR (428 +/- 40 vs 510 +/- dyn.s.cm-5), respectively. Similarly losartan compared to placebo resulted in a significant reduction in MAP (87 +/- 4.5 vs 93 +/- 3.2 mmHg) and SVR (1293 +/- 94 vs 1462 +/- 112 dyn.s.cm-5), and significantly increased CO (5.58 +/- 0.43 vs 5.31 +/- 0.42 l/min). In addition, plasma aldosterone was significantly lower after treatment with losartan compared to placebo: 76 +/- 23 vs 164 +/- 43 pg/ml respectively. CONCLUSIONS: Thus, selective type 1 ANG II receptor blockade appears to have beneficial pulmonary and endocrine effects, suggesting a possible therapeutic role in the management of hypoxaemic cor pulmonale.

Aged↗

PubMed2002

Detection of low-molecular-weight proteins in urine by dipsticks.

BACKGROUND: Testing of urines with dipsticks for proteinuria, glycosuria, etc., is common practice. A deficiency with currently available dipsticks is their lack of chemical sensitivity and underestimation of low-molecular-weight proteins such as light chains. METHODS: We experimented with a number of dyes that gave an easily recognized color change on dipsticks for various low-molecular-weight proteins such as alpha-1-glycoprotein, alpha-1- and beta-2-microglobulin, and kappa and lambda light chains. We were successful in formulating a dye for impregnating dipsticks that gave a color change with low-molecular-weight proteins. RESULTS: Most dipsticks will measure proteins down to about 1 g/l. Our composite of two dyes (described here as the "TPR" dipsticks) gave reproducible results for protein concentrations of >/=300 mg/l, and detected low-molecular proteins. The TPR reagent is resistant to interferences from many compounds; also, the protein results are not altered in a given urine at a pH between 5 and 8. CONCLUSIONS: We have developed a dipstick that detects low-molecular-weight proteins. The dipsticks are easy to use and are suitable for outpatient or point-of-care testing. The precision of the dipsticks is satisfactory and is only marginally lower than quantitative spectrophotometric methods using pyrogallol red (PYR).

Coloring Agents↗

PubMed2002

Interaction of FLU, a negative regulator of tetrapyrrole biosynthesis, with the glutamyl-tRNA reductase requires the tetratricopeptide repeat domain of FLU.

Regulation of tetrapyrrole biosynthesis in plants has been attributed to feedback control of glutamyl-tRNA reductase (GLU-TR) by heme. Recently, another negative regulator, the FLU protein, has been discovered that operates independently of heme. A truncated form of FLU that contains two domains implicated in protein-protein interaction was co-expressed in yeast with either GLU-TR or glutamate-1-semialdehyde-2-1-aminotransferase (GSA-AT), the second enzyme involved in delta-aminolevulinic acid (ALA) biosynthesis. FLU interacts strongly with GLU-TR but not with GSA-AT. Two variants of FLU that carry single amino acid exchanges within their coiled coil and tetratricopeptide repeat (TPR) domains, respectively, were also tested. Only the FLU variant with the mutated TPR motif lost the capacity to interact with GLU-TR.

Aldehyde Oxidoreductases↗

PubMed1999

Tpr1, a Schizosaccharomyces pombe protein involved in potassium transport.

The Schizosaccharomyces pombe Tpr1 was isolated as suppressor of the Saccharomyces cerevisiae Delta trk1,2 potassium uptake deficient phenotype. Tpr1, for tetratrico peptide repeat, encodes a 1039 amino acid residues protein with several reiterated TPR units displaying significant homology to p150(TSP), a recently identified phosphoprotein of mouse, to S. cerevisiae CTR9 and to related sequences of human, Caenorhabditis elegans, Methanoccocus jannaschii and Arabidopsis thaliana. Expression of Tpr1 restored growth on 0.2 mM K(+) media, induced K(+) transport with a K(T) of 4.6 mM and resumed inward currents of -90 pA at -250 mV (pH 7.2) conducting K(+) and other alkali-metal ions. The tetratrico peptide repeat is a degenerate motif of 34 amino acids that is repeated several times within TPR-containing proteins and has been suggested to mediate protein-protein interactions. The sequence and putative binding properties of Tpr1 suggest the protein unlikely as transporter but involved in the enhancement of K(+) uptake via conventional carriers.

Aldose-Ketose Isomerases↗

PubMed2002

Determination of chlorophenols by solid-phase microextraction and liquid chromatography with electrochemical detection.

A solid-phase microextraction method has been developed for the determination of 19 chlorophenols (CPs) in environmental samples. The analytical procedure involves direct sampling of CPs from water using solid-phase microextraction (SPME) and determination by liquid chromatography with electrochemical detection (LC-ED). Three kinds of fibre [50 microm carbowax-templated resin (CW-TPR), 60 microm polydimethylsiloxane-divinylbenzene (PDMS-DVB) and 85 microm polyacrylate (PA)] were evaluated for the analysis of CPs. Of these fibres, CW-TPR is the most suitable for the determination of CPs in water. Optimal conditions for both desorption and absorption SPME processes, such as composition of the desorption solvent (water-acetonitrile-methanol, 20:30:50) and desorption time (5 min), extraction time (50 min) and temperature (40 degrees C) as well as pH (3.5) and ionic strength (6 g NaCl) were established. The precision of the SPME-LC-ED method gave relative standard deviations (RSDs) of between 4 and 11%. The method was linear over three to four orders of magnitude and the detection limits, from 3 to 8 ng l(-1), were lower than the European Community legislation limits for drinking water. The method was applied to the analysis of CPs in drinking water and wood samples.

Chlorophenols↗

PubMed2003

Solid-phase microextraction coupled with high-performance liquid chromatography for the determination of phenylurea herbicides in aqueous samples.

Solid-phase microextraction coupled with high-performance liquid chromatography was successfully applied to the analysis of nine phenylurea herbicides (metoxuron, monuron, chlorotoluron, isoproturon, monolinuron, metobromuron, buturon, linuron, and chlorbromuron). Polydimethylsiloxane-divinylbenzene (PDMS-DVB, 60 microm) and Carbowax-templated resin (CW-TPR, 50 microm) fibers were selected from four commercial fibers for further study because of their better extraction efficiencies. The parameters of the desorption procedure were studied and optimized. The effects of the properties of analytes and fiber coatings, carryover, duration and temperature of absorption, pH, organic solvent and ionic strength of samples were also investigated. External calibration with an aqueous standard can be used for the analysis of environmental samples (lake water) using either PDMS-DVB or CW-TPR fibers. Good precisions (1.0-5.9%) are achieved for this method, and the detection limits are at the level of 0.5-5.1 ng/ml.

Calibration↗

PubMed1999

Determination of hydroxyaromatic compounds in water by solid-phase microextraction coupled to high-performance liquid chromatography.

Solid-phase microextraction (SPME) coupled with high-performance liquid chromatography (HPLC) for the analysis of hydroxyaromatic compounds is described. Three kinds of fibers [50 microns carbowax-templated resin (CW-TPR), 60 microns polydimethylsiloxane-divinylbenzene (PDMS-DVB) and 85 microns polyacrylate (PA) fibers] were evaluated. CW-TPR and PDMS-DVB were selected for further study. The parameters of the desorption procedure (such as desorption mode, the composition of the solvent for desorption and the duration of fiber soaking) were studied and optimized. The effect of the structure and physical properties of analytes, carryover, duration of absorption, temperature of absorption, pH and ionic strength of samples were also investigated. The method was applied to environmental samples (lake water) using a simple calibration curve.

Adsorption↗

PubMed2003

A study of thoria on the surface of gamma-Al2O3.

The dispersion of thoria on the surface of gamma-Al2O3 and the surface properties of ThO2/gamma-Al2O3 samples, as well as the influence of the loading amount of thoria on the reduction behavior of copper oxide species, have been studied using XRD, XPS, FTIR, and TPR. The results indicate that the dispersion capacity of thoria, like that of ceria, is much lower than for two other tetravalent metal oxides, zirconia and titania, and the surface adsorption amount of the carbonyl compound and H2O slightly increases with increasing thoria loading. The different thoria loadings can influence the reduction behavior of the dispersed copper oxide by comparing the TPR results of CuO/ThO2/gamma-Al2O3 samples. In addition, the lower dispersion capacities of thoria and ceria on gamma-Al2O3 are tentatively discussed by considering the structural stability of the two oxides.

Journal Article↗

PubMed2001

Similar patterns of cardiovascular response during emotional activation as a function of affective valence and arousal and gender.

OBJECTIVE: Laboratory studies of emotion-induced cardiovascular responses have been conducted predominantly with a specific affects approach rather than a dimensional approach. The purpose of this study was to apply the principles of the Circumplex Model of Affect (i.e., valence and arousal) to investigate cardiovascular reactivity during emotional activation in men and women. METHODS: Forty-two healthy university students (mean age = 19.45, 52% women, 58% Caucasian) engaged in personally relevant recall tasks that varied as a function of valence and arousal. Self-reported valence and arousal, systolic and diastolic blood pressure (SBP and DBP, respectively), heart rate (HR), preejection period (PEP), stroke index (SI), cardiac index (CI), and total peripheral resistance (TPR) were measured during baseline and task periods. RESULTS: Cardiovascular responses were found to be largely comparable across the recall tasks and were characterized by significant increases in blood pressure, HR, and TPR, and decreases in SI (Ps < .001). In addition, SBP during negative valence tasks was significantly higher than during positive valence tasks (P < .03), and PEP lengthened more during low as compared to high arousal tasks (P < .03). CONCLUSIONS: These results highlight the similarity of hemodynamic adjustments during the verbal expression of emotion across gender and the dimensions of valence and arousal. The overall response pattern suggests alpha-adrenergically mediated sympathetic activation and vagal withdrawal.

Adolescent↗

PubMed2002

Acculturation and cardiovascular reactivity of second-generation Turkish migrants in Germany.

OBJECTIVE: Previous studies have shown that migration and acculturation lead to higher blood pressures and a higher prevalence of cardiovascular diseases. Heightened cardiovascular reactivity is considered as a risk factor for cardiovascular diseases. Therefore, the purpose of the present study was to examine cardiovascular reactivity in young and healthy second-generation Turkish migrants to Germany. METHOD: Forty-one Turkish and 20 German male students worked on a mental arithmetic task for 6 min and underwent the cold pressor test for 90 s. Heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were taken in intervals of 2 min at baseline and during task periods. Stroke volume (SV), cardiac output (CO), preejection period (PEP), and total peripheral resistance (TPR) were registered continuously by impedance cardiography. The Turkish volunteers were divided into weak and advanced acculturated migrants based on self-ratings given in a questionnaire. RESULTS: Advanced acculturated Turkish students showed greater HR and CO increases and greater PEP and TPR decreases to the mental arithmetic task than Germans or weak acculturated Turkish students. No group differences were found for the cold pressor test. CONCLUSION: Migrants' acculturation is associated with an enhanced beta-adrenergic activation pattern of the sympathetic nervous system that might put them at greater risk with regards to essential hypertension and coronary heart disease.

Adaptation, Psychological↗

PubMed1997

Hemodynamic responses to the stroop and cold pressor tests after submaximal cycling exercise in normotensive males.

The effect of 30 min of cycling exercise at 60% VO2max on hemodynamic responses to the Stroop and cold pressor tests in 12 normotensive males was examined. Subjects were randomly assigned in a counterbalanced design to perform the stressors pre- and postexercise and served as their own controls. Cardiac output (CO), heart rate (HR), and stroke volume were measured continuously by impedance cardiography. Blood pressure was measured beat to beat using a photoplethysmographic volume transducer. Total peripheral resistance (TPR) was calculated. The systolic blood pressure response (elevation) to the Stroop test was significantly attenuated postexercise (4.2 +/- 1.4%, p < 0.05) as compared to preexercise and control (10.1 +/- 1.8%). Postexercise HR reactivity was also significantly attenuated to the Stroop test postexercise (0.3 +/- 1.7%) compared to preexercise and control (6.5 +/- 2.3%, p < 0.05). Hemodynamic variables among treatment groups, with the possible exception of HR, appeared to be unaffected during the cold pressor postexercise. Neither central (i.e., CO) nor peripheral (i.e., TPR) responses appeared to be solely responsible for the attenuated blood pressure response to the Stroop stressor.

Adult↗

PubMed2005

Purification and assay of the chaperone-dependent ubiquitin ligase of the carboxyl terminus of Hsc70-interacting protein.

It is notable that both chaperone and ubiquitin-proteasome systems are required for the removal of aberrant cellular proteins to ensure protein homeostasis in cells. However, the entity that links the two systems had remained elusive. The carboxyl terminus of Hsc70-interacting protein (CHIP), originally identified as a cochaperone of Hsc70, has both a TPR motif and a U-box domain. The TPR motif associates with Hsp70 and Hsp90, whereas the U-box domain executes ubiquitin ligase activity. Thus, CHIP is an ideal molecule, acting as a protein quality control ubiquitin ligase that selectively leads abnormal proteins recognized by molecular chaperones to degradation by the proteasome. This chapter describes methods of analyzing chaperone-dependent ubiquitin ligase activity of CHIP using firefly luciferase as a model substrate.

Animals↗

PubMedDate not supplied

System identification of dynamic closed-loop control of total peripheral resistance by arterial and cardiopulmonary baroreceptors.

Prolonged exposure to microgravity in space flight missions (days) impairs the mechanisms responsible for defense of arterial blood pressure (ABP) and cardiac output (CO) against orthostatic stress in the post-flight period. The mechanisms responsible for the observed orthostatic intolerance are not yet completely understood. Additionally, effective counter measures to attenuate this pathophysiological response are not available. The aim of this study was to investigate the ability of our proposed system identification method to predict closed-loop dynamic changes in TPR induced by changes in mean arterial pressure (MAP) and right atrial pressure (RAP). For this purpose we designed and employed a novel experimental animal model for the examination of arterial and cardiopulmonary baroreceptors in the dynamic closed-loop control of total peripheral resistance (TPR), and applied system identification to the analysis of beat-to-beat fluctuations in the measured signals. Grant numbers: NAG5-4989.

Animals↗

PubMed2004

Bupropion and paroxetine differentially influence cardiovascular and neuroendocrine responses to stress in depressed patients.

BACKGROUND: There exists a need to identify safe and effective treatments for depression in patients with coronary heart disease (CHD). METHODS: Using a cross-sectional design, 17 depressed patients being treated with bupropion (200-450 mg/day) were compared with 17 depressed patients being treated with paroxetine (10-50 mg/day) and with a group of 15 unmedicated, non-depressed controls for cardiovascular, neuroendocrine and heart rate variability (HRV) measures at rest and in response to mental and physical stressors. RESULTS: Regardless of treatment, both treated groups exhibited blunted plasma cortisol, plasma epinephrine, systolic blood pressure, cardiac output, and pre-ejection period responses to mental stressors relative to controls. Bupropion treated individuals exhibited greater total peripheral resistance (TPR) increases than either the paroxetine or control groups, and greater plasma norepinephrine (NE) increases to mental stressors than the paroxetine group. The bupropion group also displayed reduced HRV at rest relative to the controls and during orthostatic challenge relative to both the control and paroxetine groups. LIMITATIONS: Despite the fact that the treated groups were well matched for depression and other psychiatric histories, lack of randomization into treatment arms may be associated with a selection bias in the two treated groups. CONCLUSIONS: Although both pharmacological treatments were associated with a blunting of some cardiovascular and neuroendocrine responses to stress relative to controls, which may be reflective of their therapeutic mechanisms of action, the results of our study also suggest that bupropion is associated with a more detrimental autonomic profile than paroxetine, as reflected in increased TPR and NE, and reduced HRV. The results of this study may have implications for the pharmacological treatment of depression in CHD patients.

Adult↗

PubMed1999

Effects of treatment of obstructive sleep apnea on circadian hemodynamics.

INTRODUCTION: The role of obstructive sleep apnea syndrome (OSAS) in the etiology of daytime hypertension is still an issue of debate, which is fed by the high prevalence of the syndrome in hypertensive patients. In this study the anti-hypertensive effect of short-term treatment of obstructive sleep apnea with nasal continuous positive airway pressure (nCPAP) was assessed. PATIENTS AND METHODS: In eight patients with documented OSAS (mean apnea index 62 apneas/h), two 24-h continuous finger blood pressure registrations (Portapres) were performed. At baseline and after 3 weeks of treatment with nCPAP. Ten hypertensive control subjects were studied. Stroke volume (SV), cardiac output (CO) and total peripheral resistance (TPR) were assessed by pulse contour analysis. RESULTS: Hemodynamics were highly reproducible in the controls. nCPAP therapy improved apnea-activity in all OSAS patients. This was associated with a reduction of nighttime systolic (SBP), mean arterial (MAP) and diastolic blood pressure (DBP). Treatment also reduced daytime MAP by -11 mm Hg (ranging from -27 to 1; P < 0.05), and DBP by -7 mm Hg (-24 to 3; P < 0.05). CO was significantly increased in daytime by 9% (-4 to 25; P < 0.05), whereas TPR was reduced by -15% (-34 to 3; P < 0.05). CONCLUSIONS: Treatment of OSAS caused a reduction in daytime MAP and DBP, associated with a reduction of vascular resistance. These findings are consistent with the hypothesis of a reduced sympathetic outflow at night after therapy of obstructive sleep apnea, carrying over to the day.

Adult↗