The Role of Spinal Neurokinin-2 Receptors in the Processing of Nociceptive Information from the Joint and in the Generation and Maintenance of Inflammation-evoked Hyperexcitability of Dorsal Horn Neurons in the Rat

In spinal cord neurons in anesthetized rats, the role of neurokinin A and neurokinin-2 receptors in the processing of nociceptive information from the knee joint was studied. The specific non-peptide antagonist at the neurokinin-2 receptor, SR48968, its inactive R -enantiomer, SR48965, neurokinin A, substance P and ( R, S )-α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA), were administered ionophoretically close to neurons with input from the knee joint. SR48968 reduced the effects of exogenous neurokinin A, but not those of exogenous substance P and AMPA, indicating selective blockade of neurokinin-2 receptors. In most neurons with input from the normal knee joint, SR48968 reduced dose-dependently the responses to noxious pressure applied to the knee, and in ˜50% of the neurons the responses to innocuous pressure. The administration of SR48968 during the induction of an experimental joint inflammation markedly attenuated the development of inflammation-evoked hyperexcitability. In hyperexcitable neurons with input from the inflamed joint, SR48968 reduced the responses to noxious and innocuous pressure. The relative reduction of the responses was more pronounced than in neurons with input from the normal joint. None of the effects of SR48968 was mimicked by SR48965. These data show that neurokinin-2 receptors are involved in the spinal processing of nociceptive information from the normal joint. Furthermore, neurokinin-2 receptors must be coactivated at an early stage of inflammation, to allow the generation of hyperexcitability. Finally, neurokinin-2 receptors are involved in the maintenance of hyperexcitability during inflammation. In summary, spinal neurokinin-2 receptors are important in the generation of pain in the normal and inflamed joint.     

Vasoconstrictor responses to the P2x-purinoceptor agonist beta, gamma-methylene-L-ATP in human cutaneous and renal blood vessels.

1. Strips of human saphenous veins and of human renal arteries and veins were superfused with Krebs-Henseleit solution at 37 degrees C. Constrictor responses were elicited by exogenous noradrenaline and the P2x-purinoceptor-selective agonist, beta, gamma-methylene-L-ATP. 2. In human saphenous veins, beta, gamma-methylene-L-ATP (0.3-30 microM; EC50 2.2 microM) induced marked constrictor responses. The maximal response to beta, gamma-methylene-L-ATP was similar to the maximal response to noradrenaline. The P2-purinoceptor antagonist suramin (30 microM) shifted the concentration-response curve of beta, gamma-methylene-L-ATP to the right (apparent pKB value 4.8); suramin (100 microM) markedly inhibited the responses to beta, gamma-methylene-L-ATP. The preferential P2x-purinoceptor antagonist, pyridoxal-phosphate-6-azophenyl-2',4'-disulphonic acid (PPADS; 3 microM) slightly reduced the response to beta, gamma-methylene-L-ATP. At a ten times higher concentration (30 microM), PPADS almost abolished the responses to beta, gamma-methylene-L-ATP. PPADS (30 microM), in contrast, caused no significant change in the concentration-response curve of noradrenaline. 3. In extrarenal and intrarenal arteries, EC50 values and maximal responses to noradrenaline were similar when compared with responses to noradrenaline in saphenous veins. Noradrenaline also constricted extrarenal veins. However, in contrast to the results obtained on saphenous veins, beta, gamma-methylene-L-ATP caused almost no constrictor responses in extrarenal veins and arteries and only moderate responses in intrarenal arteries. 4. The results demonstrate marked differences in responsiveness of human blood vessels to the selective P2x-purinoceptor agonist, beta, gamma-methylene-L-ATP, suggesting tissue differences in the occurrence or operation of P2x-purinoceptors in human vascular tissues. Moreover, the results indicate that PPADS blocks P2x-purinoceptors in human isolated blood vessels as previously demonstrated in animal blood vessels.     

Effects of an experimental arthritis on the sensory properties of fine articular afferent units

An acute experimental arthritis was induced in the right knee joint of adult cats anesthetized with chloralose, and the activity of single fine afferent units of the medial articular nerve was recorded from filaments of the saphenous nerve. All units included in this study were sensitive to local mechanical probing of the medial and anteromedial aspects of the knee joint. The units were identified by their conduction velocity as belonging either to group III (2.5-20 m/s, 48 U) or group IV (less than 2.5 m/s, 29 U). After the identification, the resting activity was measured, and the evoked activity was determined using local mechanical stimulation with glass rods and von Frey hairs, and passive movements of the knee joint. The results were compared with those obtained in a similar study of fine articular units from normal joints. Resting activity was observed in 75% of the group III and 83% of the group IV units. The discharges were irregular and often of high frequency. Both the percentages of units with resting activity and the frequencies of their discharges were more than twice as high as in the control sample. Nearly all units from inflamed joints had low threshold to movements (group III 89%, group IV 72%), and most units responded well to flexion and extension. In contrast, in units from normal joints only 33% of the group III and 10% of the group IV units responded well to passive movements in the normal working range of the joint. In inflamed as well as in normal joints the responses were mostly tonic in character and adapted slowly or not at all when the joint was held in a new position. In normal joints 24% of the group III and 36.5% of the group IV afferent units with local mechanosensitive receptive fields could not be excited by any physiological or noxious joint movements. Such units were only very occasionally seen in the present sample. The average number of receptive fields per unit found in inflamed joints exceeded considerably that in normal units, but no systematic drop in von Frey thresholds was seen when comparing the control sample with the inflamed one. From the above data we conclude that an acute inflammation sensitizes many fine articular units, making them active at rest and increasing the responsiveness more readily to normally innocuous joint movements. Both nociceptors and units with low threshold to movement seem to become sensitized by the inflammation.(ABSTRACT TRUNCATED AT 400 WORDS)     

Interrelationship between TP53 gene deletion, protein expression and chromosome 17 aneusomy in gastric adenocarcinoma

Background  

This study evaluates the existence of numerical alterations of chromosome 17 and TP53 gene deletion in gastric adenocarcinoma. The p53 protein expression was also evaluated, as well as, possible associations with clinicopathological characteristics.     

Apoptotic vesicles crossprime CD8 T cells and protect against tuberculosis

CD8 T lymphocytes are important effectors in protective immunity against Mycobacterium tuberculosis. We recently characterized the detour pathway of CD8 T cell activation in tuberculosis mediated by apoptotic vesicles from infected cells that transport mycobacterial antigens to dendritic cells (DCs). Here we demonstrate that apoptotic vesicles from mycobacteria-infected macrophages stimulate CD8 T cells in vivo. Homing of DCs to draining lymph nodes was critically required for effective crosspriming. Subsequent fate of vesicle-associated antigens in recipient DCs was characterized by endosomal mechanisms predominating over proteasomal processing. In addition, vesicle processing depended on the presence of saposins to disintegrate apoptotic membranes. Apoptotic vesicles displayed potent adjuvant activity by stimulating through Toll-like receptors (TLR). Ultimately, vaccination with vesicles from infected cells induced protection against M. tuberculosis infection. Taken together, we propose the detour pathway to represent a genuine immunological mechanism mediating crosspriming of CD8 T cells in vivo and protection against tuberculosis.     

Grundlagenorientierte Schmerzforschung

Ohne Zusammenfassung     

Increased Ca2+ sensitivity of myofibrillar tension in ischaemic vs dilated cardiomyopathy

1. There is evidence that different aetiologies of heart failure, especially ischaemic vs dilated cardiomyopathy (ICM and DCM, respectively), may influence the prognosis of patients with this disease. Patients with ICM have a worse prognosis than those with DCM; the mechanisms underlying this difference have not yet been clarified. The aim of the present study was to investigate whether there are changes in myofibrillar function depending on the aetiology of human heart failure. 2. Ca²⁺‐dependent tension (DT) and actomyosin ATPase acitivity (MYO) in Triton X‐skinned fibre preparations of the left ventricular myocardium from patients with heart failure due to ICM (n = 5) and DCM (n = 5) were measured. Tension‐dependent ATP consumption was calculated by the ratio of DT and MYO (‘tension cost’). Non‐failing myocardium (NF) from donor hearts, which could not be transplanted because of technical reasons, was evaluated as a control. 3. Although DT was reduced, the myofibrillar Ca²⁺ sensitivity of DT and MYO, as well as tension cost, were increased in preparations from ICM and DCM myocardium compared with NF. The Ca²⁺ sensitivity of DT and MYO was significantly increased in ICM compared with DCM preparations, resulting in more economic cross‐bridge cycling in ICM than in DCM. 4. In conclusion, ICM is associated with an increased Ca²⁺ sensitivity of myofibrillar tension and ATPase activity accompanied by decreased tension cost compared with DCM. Thus, the worse prognosis associated with ICM does not seem to be due to differences in myofibrillar function.