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1.
Nutrients ; 16(14)2024 Jul 09.
Article in English | MEDLINE | ID: mdl-39064633

ABSTRACT

The current study aimed to evaluate the effect different modalities (pictures and words) of food stimuli have on inhibitory control under different homeostatic states. To this end, the homeostatic state was altered by asking participants to fast for 16 h (n = 67) or eat lunch as usual (n = 76) before completing an online stop-signal task with modal (pictures) and amodal (words) food and valenced-matched non-food stimuli. The inclusion of non-food stimuli allowed us to test the food specificity of the effect. We found a significant Group × Modality × Stimulus Type interaction (F(1,141) = 5.29, p = 0.023, ηp2 = 0.036): fasted individuals had similar inhibitory capacity for modal and amodal food stimuli but better inhibitory capacity for non-food words compared to images, while there were no inhibitory differences in dependence on either modality or stimulus type in satiated individuals. Thus, we were able to show that inhibitory capacities to modal compared to amodal stimuli depend on participants' current state of fasting. Future studies should focus on how this lowered inhibitory capacity influences food intake, as well as the role of stimulus valence in cognitive processing, to clarify potential implications for dieting and weight loss training.


Subject(s)
Fasting , Inhibition, Psychological , Humans , Fasting/physiology , Female , Male , Young Adult , Adult , Eating/psychology , Eating/physiology , Food , Photic Stimulation/methods , Satiation/physiology
2.
Eur Eat Disord Rev ; 32(1): 90-98, 2024 Jan.
Article in English | MEDLINE | ID: mdl-37612812

ABSTRACT

OBJECTIVE: Restrained eaters (RE) show behaviourally unregulated food intake, which is often explained by a deficit in inhibitory control. Despite evidence for general inhibitory deficits in RE, it remains unclear how the variety of (food) cues in our environment can influence cognitive control. METHOD: In this re-analysis, we explored the inhibitory capacity of RE and unrestrained eaters (URE) on a stop-signal task with modal (pictures) and amodal (word) food and non-food stimuli. RESULTS: Although we did not find the expected inhibitory deficits in RE compared to URE, we found a significant Group × Modality × Stimulus Type interaction. This indicated that RE have relatively good inhibitory control for food, compared to non-food modal cues, and that this relationship is reversed for amodal cues. CONCLUSIONS: Hence, we showed differential processing of information based on food-specificity and presentation format in RE. The format of food cues is thus an important new avenue to understand how the food environment impedes those struggling with regulating their eating behaviour.


Subject(s)
Cues , Food , Humans , Feeding Behavior/psychology , Inhibition, Psychological , Eating/psychology
3.
Eur J Trauma Emerg Surg ; 49(2): 875-884, 2023 Apr.
Article in English | MEDLINE | ID: mdl-36266477

ABSTRACT

PURPOSE: In the last decades, total elbow arthroplasty, elbow osteosynthesis and revision surgery have been more popularized. The study aimed to assess the course of the anconeus branch of the radial nerve in relation to two variations of the lateral para-olecranon approach, considering iatrogenic nerve injuries. METHODS: The study consisted of 120 upper extremities from 60 Thiel-embalmed human specimens. Two randomized versions of the lateral para-olecranon approach (centrally orientated: P1 and laterally orientated: P2) were performed. The olecranon and the intersection points to the anconeus branch of the radial nerve were determined as anatomical landmarks. The measurements were assessed by two independent observers. Differences were analyzed using the Student's t test; associations were computed with the Pearson correlation (r). An alpha of 0.05 (p) and a confidence interval of 95% were set. RESULTS: The intersection points averaged 12.3 cm (SD 1.8, range 8.2-16.8) for P1 versus 5.5 cm (SD 1.4, range 3.0-9.2) for P2 (p ≤ 0.001). Statistically significantly higher values for male and longer humeral specimens were revealed (all values: p < 0.05). Comparison of left and right sides yielded no difference. Excellent inter-rater agreements were found (ICC = 0.902, range 0.860-0.921). A correlation was evaluated between the humeral length and the distances in both approaches (P1: r = 0.550, p < 0.001, P2: r = 0.669, p < 0.001). CONCLUSION: The data presented here allow preservation of the anconeus branch. The P1 forms a potential advantage by owing a broader safe zone. Using the centrally orientated approach seems to provide adequate nerve protection during surgery for one of the motor branches for extension of the elbow joint and might result in improved postoperative benefits.


Subject(s)
Elbow Joint , Olecranon Process , Male , Humans , Elbow Joint/surgery , Olecranon Process/surgery , Elbow/surgery , Humerus/surgery , Muscle, Skeletal/surgery
4.
Ann Anat ; 243: 151958, 2022 Aug.
Article in English | MEDLINE | ID: mdl-35644467

ABSTRACT

BACKGROUND: The aim of the study was to design a convenient technique for dorsal minimally invasive plate osteosynthesis (MIPO) of extra-articular fractures of both distal thirds of the humeral shaft as well as to characterise the course and proximity of the radial nerve (RN) and the axillary nerve (AN). METHODS: The collective consisted of 20 upper extremities of human adult body donors. A 3.5 mm Locking Compression Plate (LCP), an extra-articular distal humerus plate was inserted through a MIPO approach including two incisions. The primary incision was performed 5 cm in lenght on the dorsal side of the lateral epicondyle. An additional 5 cm incision was conducted distal to the humeral deltoid muscle insertion and the RN was depicted. The longest suitable plate was advanced under nerve protection starting distally and fixed by locking screws. A third incision with a length of 5 cm was made beginning at the distal border of the deltoid muscle, and a muscle split was performed to dissect the AN. The respective plate holes, where the AN and RN were located and the distances between the nerves were examined. RESULTS: The RN was mostly (30%) localised on holes 6 and 7 (starting distally). The AN laid directly on the plate in 65% and on the most proximal plate hole in 12 cases, but was never situated underneath the plate. The distance between the AN and RN was at mean 93.5 mm. CONCLUSIONS: MIPO via a dorsal method proves to be a noteworthy technique and valuable option as indicated by our results. This 5-5-(5) concept may be performed as a two-incision or three-incision technique for extra-articular fractures of both distal thirds of the humerus.


Subject(s)
Humeral Fractures , Surgical Wound , Adult , Bone Plates , Feasibility Studies , Fracture Fixation, Internal/methods , Humans , Humeral Fractures/surgery , Humerus/surgery , Minimally Invasive Surgical Procedures/methods , Treatment Outcome
5.
Brain Sci ; 12(4)2022 Mar 25.
Article in English | MEDLINE | ID: mdl-35447972

ABSTRACT

Sleep and Attention-Deficit/Hyperactivity Disorder (ADHD) have repeatedly been found to be associated with each other. However, the ecological validity of daily life studies to examine the effect of sleep on ADHD symptoms is rarely made use of. In an ambulatory assessment study with measurement burst design, consisting of three bursts (each 6 months apart) of 18 days each, 70 German schoolchildren aged 10-12 years reported on their sleep quality each morning and on their subjective ADHD symptom levels as well as their sleepiness three times a day. It was hypothesized that nightly sleep quality is negatively associated with ADHD symptoms on the inter- as well as the intraindividual level. Thus, we expected children who sleep better to report higher attention and self-regulation. Additionally, sleepiness during the day was hypothesized to be positively associated with ADHD symptoms on both levels, meaning that when children are sleepier, they experience more ADHD symptoms. No association of sleep quality and ADHD symptoms between or within participants was found in multilevel analyses; also, no connection was found between ADHD symptoms and daytime sleepiness on the interindividual level. Unexpectedly, a negative association was found on the intraindividual level for ADHD symptoms and daytime sleepiness, indicating that in moments when children are sleepier during the day, they experience less ADHD symptoms. Explorative analyses showed differential links of nightly sleep quality and daytime sleepiness, with the core symptoms of inattention and hyperactivity/impulsivity, respectively. Therefore, future analyses should take the factor structure of ADHD symptoms into account.

6.
Indian J Orthop ; 55(Suppl 2): 330-335, 2021 Jul.
Article in English | MEDLINE | ID: mdl-34306545

ABSTRACT

BACKGROUND: The aim of our study was to project the A1-pulley of the thumb onto the total thumb length to enable its complete division with and without direct sight. MATERIALS AND METHODS: The study involved 50 hands from adult human cadavers. The proximal and distal borders of the A1-pulley were measured with reference to the first metacarpophalangeal joint (MCPJ). The length of the thumb was defined as the interval between the first carpometacarpal joint (CMCJ) and the apex of the thumb. The length of the pulley is calculated proportionally with reference to the line between the first CMCJ and apex of the thumb. RESULTS: Approximated by computing 95% confidence intervals, the pulley can be expected to lie in an area between 34.0% (proximal border) and 57.8% (distal border) alongside this line. CONCLUSION: Percutaneous and minimally-invasive division of the A1-pulley needs to be performed between 34.0 and 57.8% of the length between the first CMCJ and apex of the thumb.

7.
Plast Reconstr Surg ; 147(6): 1361-1367, 2021 Jun 01.
Article in English | MEDLINE | ID: mdl-34019506

ABSTRACT

BACKGROUND: The aim of this study was to investigate the axillary nerve's location along superficial anatomical landmarks, and to define a convenient risk zone. METHODS: A total of 123 upper extremities were evaluated. After dissection of the axillary nerve, the vertical distance between the upper border of the anterolateral edge of the acromion and the proximal border of the nerve was measured. Furthermore, the interval between the proximal border and the distal border of the axillary nerve's branches was evaluated. The interval between the distal border of the branches and the most distal part of the lateral humeral epicondyle was measured. The distance between the anterolateral edge of the acromion and the lateral humeral epicondyle was evaluated. Measurements were expressed as proportions with respect to the distance between the acromion and the lateral humeral epicondyle. RESULTS: The distance between the acromion and the proximal border of the axillary nerve's branches was at a height of 10 percent of the distance between the acromion and the lateral humeral epicondyle, starting from the acromion (90 percent when starting from the lateral humeral epicondyle). The interval between the proximal and distal margins of the axillary nerve's branches was between 10 percent and 30 to 35 percent of this interval, starting from the acromion (65 to 70 percent when starting from the lateral humeral epicondyle). CONCLUSIONS: The authors were able to locate the branches of the axillary nerve at an interval between 10 and 35 percent of the distance between the acromion and the lateral humeral epicondyle, starting from the acromion. This makes the proximal third of this distance an easily applicable risk zone during shoulder surgery.


Subject(s)
Anatomic Landmarks , Axilla/innervation , Peripheral Nerves/anatomy & histology , Shoulder/innervation , Aged , Aged, 80 and over , Cadaver , Female , Humans , Male , Middle Aged
8.
Indian J Orthop ; 54(Suppl 1): 188-192, 2020 Sep.
Article in English | MEDLINE | ID: mdl-32952929

ABSTRACT

BACKGROUND: Posterior interosseous nerve (PIN) entrapment syndrome is a rare condition and is predisposed by anatomical factors such as narrow passages through fibrous arcades; whereas, the Arcade of Frohse (AF) is the most common entrapment point. The aim of this study was to evaluate the entrance and exit points of the PIN into the supinator in detail. MATERIALS AND METHODS: One hundred unpaired upper extremities underwent dissection. The PIN's entrance and exit points from the supinator were depicted. The distances between the tip of the radial head (RH) and the AF and the exit point of the PIN from the supinator were measured. Further, it was checked if the borders of the AF and the exit point were muscular, tendinous or a combination of these. RESULTS: The interval between the PIN's entry into the supinator and the tip of the RH was at a mean of 28.9 mm. Concerning the border of the AF, in 54 cases a muscular and in 46 specimens a tendinous version could be observed. The interval between the exit point of the PIN and the tip of the RH proved to be at a mean of 64.2 mm. Further, the exit's border was muscular in 65 specimens and tendinous in 35 cases. CONCLUSION: During surgical treatment of the PIN syndrome, it needs to be kept in mind that approximately one-third of all patients might also suffer from entrapment at the exit point of the PIN.

9.
Sci Rep ; 10(1): 22460, 2020 12 31.
Article in English | MEDLINE | ID: mdl-33384437

ABSTRACT

Children with attention-deficit/hyperactivity disorder (ADHD) are characterized by symptoms of inattention, impulsivity, and hyperactivity. Neurophysiological correlates of ADHD include changes in the P3 component of event-related brain potentials (ERPs). Motivated by recent advances towards a more dimensional understanding of ADHD, we investigate whether ADHD-related ERP markers relate to continuous variations in attention and executive functioning also in typically-developing children. ERPs were measured while 31 school children (9-11 years) completed an adapted version of the Continuous Performance Task that additionally to inhibitory processes also isolates effects of physical stimulus salience. Children with higher levels of parent-reported ADHD symptoms did not differ in task performance, but exhibited smaller P3 amplitudes related to stimulus salience. Furthermore, ADHD symptoms were associated with the variability of neural responses over time: Children with higher levels of ADHD symptoms demonstrated lower variability in inhibition- and salience-related P3 amplitudes. No effects were observed for ERP latencies and the salience-related N2. By demonstrating that ADHD-associated neurophysiological mechanisms of inhibition and salience processing covary with attention and executive functioning in a children community sample, our study provides neurophysiological support for dimensional models of ADHD. Also, temporal variability in event-related potentials is highlighted as additional indicator of ADHD requiring further investigation.


Subject(s)
Attention Deficit Disorder with Hyperactivity/diagnosis , Attention Deficit Disorder with Hyperactivity/psychology , Biomarkers , Attention , Attention Deficit Disorder with Hyperactivity/epidemiology , Child , Cognition , Electroencephalography , Evoked Potentials , Female , Humans , Inhibition, Psychological , Male , Social Behavior , Surveys and Questionnaires , Symptom Assessment
10.
J Phys Chem A ; 120(43): 8716-8724, 2016 Nov 03.
Article in English | MEDLINE | ID: mdl-27726368

ABSTRACT

We have combined ion mobility mass spectrometry with quantum chemical calculations to investigate the gas-phase structures of multiply negatively charged oligomers of meso-tetra(4-sulfonatophenyl)metalloporphyrins comprising the divalent metal centers ZnII, CuII, and PdII. Sets of candidate structures were obtained by geometry optimizations based on calculations at both the semiempirical PM7 and density functional theory (DFT) levels. The corresponding theoretical cross sections were calculated with the projection approximation and also with the trajectory method. By comparing these collision cross sections with the respective experimental values we were able to assign oligomer structures up to the tetramer. In most cases the cross sections of the lowest energy isomers predicted by theory were found to agree with the measurements to within the experimental uncertainty (2%). Specifically, we find that for a given oligomer size the structures are independent of the metal center but depend strongly on the charge state. Oligomers in low charge states with a correspondingly larger number of sodium counterions tend to form stacked, cofacial structures reminiscent of H-aggregate motifs observed in solution. By contrast, in higher charge states, the stack opens to form coplanar structures.

11.
J Phys Chem Lett ; 7(7): 1167-72, 2016 Apr 07.
Article in English | MEDLINE | ID: mdl-26963821

ABSTRACT

We have used both action and photoelectron spectroscopy to study the response of isolated Pd(II) meso-tetra(4-sulfonatophenyl)porphyrin tetraanions ([PdTPPS](4-)) to electronic excitation over the 2.22-2.98 eV photon energy range. The action spectrum obtained by recording the wavelength-dependent intensity of charged decay products closely resembles the absorption spectrum of PdTPPS in aqueous solution (which shows pronounced Q and Soret absorption bands). The two main decay channels observed are sulfonate group loss and, predominantly, electron emission. To better understand the electron emission channel, we have also acquired photoelectron spectra at multiple detachment photon energies covering the range probed in action spectroscopy. Upon both Q and Soret band excitation, we find that electrons are emitted in three characteristic kinetic energy ranges. The corresponding detachment processes are identified as (delayed) tunneling emission from both excited singlet and triplet states (each of which is accessed by/after one-photon absorption) as well as resonant two-photon detachment. The first triplet state lifetime of isolated [PdTPPS](4-) is significantly longer than 10 µs, possibly on the 100 µs time scale. We estimate that more than 50% of the electron emission observed upon photoexcitation occurs by way of this triplet state.

12.
Chemistry ; 20(49): 16273-8, 2014 Dec 01.
Article in English | MEDLINE | ID: mdl-25297441

ABSTRACT

Branched organic nanostructures are useful scaffolds that find multiple applications in a variety of fields. Here, we present a novel approach to dendrimer-like structures. Our design contains a rigid hydrocarbon-based core (hexaphenylxylylene/tetraethynylphenylmethane) combined with a library of N-substituted oligoglycines (so-called peptoids) providing a flexible shell. The use of click chemistry allows rapid assembly of the nanostructures. The possibility of tuning the size and the solubility of this new type of nanostructure will be advantageous for future applications such as heterogeneous catalysis.


Subject(s)
Dendrimers/chemistry , Methane/analogs & derivatives , Peptoids/chemistry , Terphenyl Compounds/chemistry , Click Chemistry , Magnetic Resonance Spectroscopy , Methane/chemistry , Models, Molecular , Nanostructures/chemistry
13.
Phys Chem Chem Phys ; 16(13): 6225-32, 2014 Apr 07.
Article in English | MEDLINE | ID: mdl-24562665

ABSTRACT

Supramolecular guest-host complexes comprising various azaporphines stacked in a coordination nanoprism consisting of tris(4-pyridyl)triazines as panels, 1,4-bis(pyridyl)benzenes as pillars and (en)Pd as hinges were synthesized according to the procedure of Fujita and coworkers and characterized as ions in the gas-phase by high-resolution electrospray ionization mass spectrometry and collision induced dissociation as well as in solution by analytical ultracentrifugation. Apart from fully filled nanoprisms we have also prepared and observed partially filled as well as empty congeners in aqueous solutions. Upon mixing room temperature solutions of two types of nanoprisms, we observe that azaporphine guest exchange reactions occur on a timescale of minutes, indicating that the formation of the guest-host complexes is reversible.


Subject(s)
Gases/chemistry , Nanostructures/chemistry , Porphyrins/chemistry , Solutions/chemistry , Aza Compounds/chemistry , Centrifugation , Copper/chemistry , Metalloporphyrins/chemistry , Spectrometry, Mass, Electrospray Ionization
14.
J Phys Chem A ; 118(2): 369-79, 2014 Jan 16.
Article in English | MEDLINE | ID: mdl-24328135

ABSTRACT

We present structures and photoelectron spectra of Mn(III) and Cu(II) meso-tetra(4-sulfonatophenyl)porphyrin (TPPS) multianions, as well as of homomolecular dimers and trimers thereof. The structural assignments are based on a combination of mass spectrometry, ion mobility measurements, and semiempirical as well as density functional theory (DFT) calculations. Depending on the type of central metal atom, two completely different dimer structural motifs are found. With a central Mn(III), the monomeric units are connected via sulfonic-acid-manganese bonds resulting in a tilted stack arrangement of porphyrin rings. With Cu(II) as the central atom, the sulfonic acid groups preferentially bind to the sodium counterions, resulting in a flat dimer structure with coplanar porphyrins. Photoelectron spectra were recorded for monomers, dimers, and trimers, each in a number of different negative charge states as determined by protonation degree (+nH). In some cases, e.g., [Cu(II)TPPS](4-), [(Mn(III)TPPS)2 + H](5-), and [(Mn(III)TPPS)3 + 3H](6-), we observe electron detachment energies close to zero, or even slightly negative. In all cases, we find a large repulsive Coulomb barrier. The observed trends in detachment energies can be interpreted in terms of a simple electrostatic model.


Subject(s)
Copper/chemistry , Manganese/chemistry , Metalloporphyrins/chemistry , Molecular Structure , Photoelectron Spectroscopy , Quantum Theory
15.
J Digit Imaging ; 26(3): 393-401, 2013 Jun.
Article in English | MEDLINE | ID: mdl-23179407

ABSTRACT

To provide prospective information about quality- and satisfaction-related product features in radiology, a customer-centered approach for acquiring clinicians' requirements and their prioritizations is essential. We introduced the Kano model for the first time in radiology to obtain such information. A Kano questionnaire, consisting of pairs of questions regarding 13 clinician requirements related to computed tomography (CT), magnetic resonance imaging (MRI) access and report turnaround time (RTT), was developed and administered. Each requirement was assigned a Kano category, and its satisfaction and dissatisfaction coefficients were calculated and presented in a Kano diagram. The data were stratified based on different clinics and on staff and resident clinicians. The time interval was evaluated between the completion of an examination and the first attempt to access the report by a clinician. Consultation for modality selection and scheduling and access to CT within 24 h and RTT within 8 to 24 h were considered as must-be requirements. Access to CT within 4 h and within 8 h, access to MRI within 8 h and within 24 h, and access to RTT within 4 h were one-dimensional requirements. The extension of operation time for CT or MRI, as well as MRI access within 4 h, was considered attractive. Eight out of nine clinics considered RTT within 8 h as a must-be requirement. There were differences in responses both among different clinics and between staff and resident clinicians. Access attempts to reports by clinicians in the first 4 h after the examination completion accounted for 65 % of CTs and 49 % of MRIs.


Subject(s)
Magnetic Resonance Imaging , Needs Assessment , Radiology/standards , Referral and Consultation , Surveys and Questionnaires , Tomography, X-Ray Computed , Hospitals, University , Humans
16.
J Chem Phys ; 136(15): 154309, 2012 Apr 21.
Article in English | MEDLINE | ID: mdl-22519328

ABSTRACT

The structures of bismuth cluster cations in the range between 4 and 14 atoms have been assigned by a combination of gas phase ion mobility and trapped ion electron diffraction measurements together with density functional theory calculations. We find that above 8 atoms the clusters adopt prolate structures with coordination numbers between 3 and 4 and highly directional bonds. These open structures are more like those seen for clusters of semiconducting-in-bulk elements (such as silicon) rather than resembling the compact structures typical for clusters of metallic-in-bulk elements. An accurate description of bismuth clusters at the level of density functional theory, in particular of fragmentation pathways and dissociation energetics, requires taking spin-orbit coupling into account. For n = 11 we infer that low energy isomers can have fragmentation thresholds comparable to their structural interconversion barriers. This gives rise to experimental isomer distributions which are dependent on formation and annealing histories.

17.
Phys Chem Chem Phys ; 14(1): 234-45, 2012 Jan 07.
Article in English | MEDLINE | ID: mdl-22071636

ABSTRACT

The structures of medium sized tin cluster anions Sn(n)(-) (n = 16-29) were determined by a combination of density functional theory, trapped ion electron diffraction and collision induced dissociation (CID). Mostly prolate structures were found with a structural motif based on only three repeatedly appearing subunit clusters, the Sn(7) pentagonal bipyramid, the Sn(9) tricapped trigonal prism and the Sn(10) bicapped tetragonal antiprism. Sn(16)(-) and Sn(17)(-) are composed of two face connected subunits. In Sn(18)(-)-Sn(20)(-) the subunits form cluster dimers. For Sn(21)(-)-Sn(23)(-) additional tin atoms are inserted between the building blocks. Sn(24)(-) and Sn(25)(-) are composed of a Sn(9) or Sn(10) connected to a Sn(15) subunit, which closely resembles the ground state of Sn(15)(-). Finally, in the larger clusters Sn(26)(-)-Sn(29)(-) additional bridging atoms again connect the building blocks. The CID experiments reveal fission as the main fragmentation channel for all investigated cluster sizes. This rather unexpected "pearl-chain" cluster growth mode is rationalized by the extraordinary stability of the building blocks.

18.
J Am Coll Radiol ; 8(9): 649-56, 2011 Sep.
Article in English | MEDLINE | ID: mdl-21889754

ABSTRACT

PURPOSE: The aim of this study was to provide better patient access to MRI within 24 hours through process improvement. METHODS: The MRI process in an academic radiology department was examined. Customer value was determined using a Kano questionnaire. Current state process and performance data were measured. Process time and process value mapping were conducted. Underlying root causes that hampered MRI process flow were identified and prioritized using a fishbone diagram and failure mode and effect analysis. Statistical analysis, queuing theory, and statistical process control were used to describe and understand process behaviors, to test hypotheses, to validate solutions, and to monitor results. RESULTS: Timely access to MRI examinations within 24 hours was identified as a key customer value. A total of 33 failure modes leading to process wastes, together with 113 potential failure causes, were worked out, of which 14 failure modes were prioritized and dealt with. Having improved the process, patient access within 24 hours increased from 53% to >90%. The mean cycle time was reduced from 52 to 39 minutes. The monthly throughput increased by 38%. Scanner productivity was increased by 32%. Revenue and savings are estimated to be about €247,000 in the first year, after subtracting all costs. CONCLUSIONS: Patient access to MRI within 24 hours has been granted for >90% of requests. Improved productivity and cost saving are achieved simultaneously.


Subject(s)
Health Services Accessibility , Magnetic Resonance Imaging , Process Assessment, Health Care , Radiology Department, Hospital/organization & administration , Academic Medical Centers , Analysis of Variance , Efficiency, Organizational , Humans , Regression Analysis , Statistics, Nonparametric , Surveys and Questionnaires , Total Quality Management
19.
Blood ; 103(7): 2593-600, 2004 Apr 01.
Article in English | MEDLINE | ID: mdl-14644996

ABSTRACT

Platelets play a key role in hemostasis through their ability to rapidly adhere to activated or injured endothelium, subendothelial matrix proteins, and other activated platelets. A strong equilibrium between activating and inhibiting processes is essential for normal platelet and vascular function, impairment of this equilibrium being associated with either thrombophilic or bleeding disorders. Both cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) have been established as crucial and synergistic intracellular messengers that mediate the effects of platelet inhibitors such as nitric oxide (NO) and prostacyclin (PG-I2). However, it was recently suggested that a rapid cGMP/cGMP-dependent protein kinase (cGK)-mediated extracellular signal-related kinase (ERK) phosphorylation promotes platelet activation. This hypothesis was examined here by evaluating established and proposed cGK activators/inhibitors with respect to their capacity to promote either platelet activation or inhibition. In particular, the regulatory role of cGK for ERK phosphorylation and thrombin-, thromboxane-, and VWF-induced platelet activation was investigated. The data obtained do not support the concept that cGK-mediated ERK phosphorylation promotes platelet activation but confirm the inhibitory role of cGK in platelet function. One explanation for these discrepancies is the novel finding that extracellular cGMP analogs potently and rapidly inhibit thrombin-, thromboxane-, and VWF-induced human platelet signaling and activation by a cGK-independent mechanism.


Subject(s)
Blood Platelets/physiology , Cyclic GMP-Dependent Protein Kinases/blood , Cyclic GMP/analogs & derivatives , Cyclic GMP/pharmacology , Platelet Aggregation Inhibitors/pharmacology , Platelet Aggregation/physiology , 8-Bromo Cyclic Adenosine Monophosphate/pharmacology , Blood Platelets/drug effects , Blood Platelets/enzymology , Calcium/blood , Cyclic GMP/blood , Humans , Kinetics , Nitric Oxide Donors/pharmacology , Platelet Aggregation/drug effects , S-Nitroso-N-Acetylpenicillamine/pharmacology , von Willebrand Factor/pharmacology
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