Knowledge about the extent of total variation experienced between samples from different individuals is of great importance for the design of not only proteomics but every clinical study. This variation defines the smallest statistically significant detectable signal difference when comparing two groups of individuals. We isolated platelets from 20 healthy human volunteers aged 56 -100 years because this age group is most commonly encountered in the clinics. We determined the technical and total variation experienced in a proteome analysis using two-dimensional DIGE with IPGs in the pI ranges 4 -7 and 6 -9. Only spots that were reproducibly detectable in at least 90% of all gels (n ‫؍‬ 908) were included in the study. All spots had a similar technical variation with a median coefficient of variation (cv) of about 7%. In contrast, spots showed a more diverse total variation between individuals with a surprisingly low median cv of only 18%. Because most known biomarkers show an effect size in a 1-2-fold range of their cv, any future clinical proteomics study with platelets will require an analytical method that is able to detect such small quantitative differences. In addition, we calculated the minimal number of samples (sample size) needed to detect given protein expression differences with statistical significance. Molecular & Cellular Proteomics 7:193-203, 2008.Biomarkers are used to differentiate between different biological states and to monitor disease progress or the success of medical treatment. To fulfill these tasks, there are not only strict requirements for each biomarker candidate in terms of selectivity and specificity but also for the precision of the analytical process. Therefore knowledge on the extent of variation between the individuals within each group is crucial for the study design as well as the selection of the method of measurement. The total variation experienced between individuals within one group is the result of the biological variation caused by factors like sex, age, genetic background, lifestyle, or health status and the technical variation introduced by the applied sample handling and the method of measurement itself. This study investigated the extent of variation in human blood platelets. Platelets are responsible for the maintenance of vascular integrity and are also involved in inflammation and wound healing (1). They are anucleate cytoplasmic fragments released from megakaryocytes in the bone marrow. During platelet biogenesis, organelles, especially the mitochondria and the ␣-and dense granules, are actively transported into the platelets. Furthermore platelets receive a certain set of mRNAs during their biogenesis from the megakaryocytes and are still capable of protein synthesis and processing (2). Several proteomics studies have focused on different aspects in platelet research using 2D 1 electrophoresis followed by mass spectrometry. These studies provided 2D maps of the total platelet proteome (3, 4), the platelet secretome (5), and the processes during platelet activ...

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(−)‐[3H]Desmethoxyverapamil and (+)‐[3P]PN 200‐110 were employed to characterize phenylalkylamineselective and 1,4‐dihydropyridine‐selective receptors on purified Ca2+ channels from guinea‐pig skeletal muscle t‐tubules. In contrast to the membrane‐bound Ca2+ channel, d‐cis‐diltiazem (EC50 = 4.5 ± 1.7 μM) markedly stimulated the binding of (+)‐[3H]PN 200‐110 to the purified ionic pore. In the presence of 100 μM d‐cis‐diltiazem (which binds to the benzothiazepine‐selective receptors) the B max for (+)‐[3H]PN 200‐110 increased from 497 ± 81 to 1557 ± 43 pmol per mg protein, whereas the K d decreased from 8.8 ± 1.7 to 4.7 ± 1.8 nM at 25°C. P‐cis‐Diltiazem was inactive. (−)‐Desmethoxyverapamil, which is a negative heterotropic allosteric inhibitor of (+)‐[3H]IN 200‐110 binding to membrane‐bound channels, stimulated 1,4‐dihydropyridine binding to the isolated channel. (−)‐[3H]Desmethoxyverapamil binding was stimulated by antagonistic 1,4‐dihydropyridines [(+)‐PN 200‐110 ⪢(−)(CR)‐202‐791 ⪢(+)(4R)‐Bay K 8644] whereas the agonistic enantiomers (+)(S)‐202‐791 and (−)(4S)‐Bay K 8644 were inhibitory and (−)‐PN 200‐110 was inactive. The results indicate that three distinct drug‐receptor sites exist on the purified Ca2+ channel, two of which are shown by direct labelling to be reciprocally allosterically coupled.

According to public opinion, Enduro motorcycling is a dangerous sport. Little is known about overuse injuries in connection with this sport. The study consisted of two phases. Phase 1 was planned as a prospective feasibility study for phase 2. The latter was initiated as a prospective investigation, comprising a random sample of the participants of phase 1. Enduro motorcyclists were interviewed with a prepared questionnaire. Clinical examinations were performed immediately before, and after, a major Enduro race, including pain assessment in the hand/wrist and the forearm using the visual analog scale. The occurrence of Raynaud's syndrome carpal tunnel syndrome (CTS), and loss of grip strength in the forearm muscles were recorded in detail. Phase 1 showed that the predominant overused anatomical regions were the hand/wrist and forearms. Nearly 50% of all the riders complained of pain or paresthetic sensations. A significant increase in pain was registered after the race. After the second run 32.28% of all riders had CTS in the left hand and 43.31% in the right hand. More than one-half of the athletes complained of overuse injuries. Transient CTS is an overuse injury closely related to sports.

Two photoreactive apamin derivatives were prepared with an aryl azide [[(azidonitrophenyl)amino]acetate (ANPAA)] group coupled at different positions on the neurotoxin molecule. These ligands were used to identify membrane components in the environment of the neuronal binding site that is associated with a Ca2+-activated K+ channel. 125I-[alpha-ANPAA-Cys1] apamin labeled a single Mr 86 000 chain in cultured neurons whereas two bands corresponding to Mr 86 000 and 59,000 were detected in synaptic membrane preparations, suggesting that the Mr 59,000 polypeptide may be a degradation product. 125I-[epsilon-ANPAA-Lys4]apamin however incorporated uniquely into two smaller components with Mr 33,000 and 22,000 in both cultured neurons and synaptic membranes. Randomly modified 125I-ANPAA-apamin gave a cross-linking profile equivalent to the sum of those obtained with the two defined derivatives. The apamin binding site seems to be located at the frontier between three or more putative K+ channel subunits which are only accessible from limited regions of the receptor-associated photoprobe. Irradiation of frozen rat brain membranes with high-energy electrons led to a reduction in 125I-apamin receptor capacity, yielding a target size for the functional binding unit of Mr 84,000-115,000, which could be constituted by the Mr 86,000 subunit alone or by the Mr 86,000 subunit in conjuction with one of the two smaller subunits.