Comparison of evoked spinal potentials by stimulation of the sciatic nerve and the spinal cord.

Spinal cord monitoring during surgery using evoked spinal potentials (ESP) is now popular. In cats, ESPs due to both sciatic nerve (SN-ESP) and spinal cord stimulation (SC-AESP and SC-DESP) were recorded from the epidural space. Both SN-ESP and SC-AESP were compared by parameter studies. Stimulus frequencies up to 100 Hz did not significantly alter the SC-AESP, whereas the later components of the SN-ESP decreased greatly in amplitude. The SN-ESP was more sensitive to asphyxia than the SC-AESP. Augmentation of the ESP occurred approximately 5 minutes after the asphyxia was introduced, which was interpreted as an impending sign of anoxia of the spinal cord. The SN-ESP had more potentials arising from synaptic and postsynaptic activities, while the SC-AESP was mainly derived from the spinal tracts. To monitor the function of the spinal cord, both methods should be used.

Foot and ankle injuries related to rock climbing. The role of footwear.

Interest in rock climbing has grown dramatically over the past decade. Although considerable research has been conducted on upper-extremity injuries sustained during rock climbing, there has been no comprehensive evaluation of lower-extremity injuries and related biomechanics. The authors performed a retrospective investigation of rock-climbing injuries using a survey of 104 active rock climbers of varying levels of expertise. The results show that 81% of the respondents have suffered acute or chronic pain or associated pathology in the foot or ankle during or after climbing. The authors propose that this morbidity has biomechanical etiologies related to the common practice among rock climbers of wearing climbing shoes that are smaller than their street shoes.

Acute renal failure associated with Candida albicans infection.

A 16-year-old male with a long history of steroid-responsive nephrotic syndrome developed fever, abdominal pain, thrombocytopenia and acute renal failure. The clinical course and renal histology were similar to, but not typical of, haemolytic uremic syndrome. Positive cultures (throat, oesophagus, stool), an elevation in serum levels of specific antibody and fungal polysaccharide (1,3) beta-D-glucan and response to the antifungal therapy indicated an association between this syndrome and infection with Candida albicans.

Arginine vasopressin stimulates phosphorylation of aquaporin-2 in rat renal tissue.

Aquaporin-2 (AQP2), the protein that mediates arginine vasopressin (AVP)-regulated apical water transport in the renal collecting duct, possesses a single consensus phosphorylation site for cAMP-dependent protein kinase A (PKA) at Ser256. The aim of this study was to examine whether AVP, and other agents that increase cAMP levels, could stimulate the phosphorylation of AQP2 in intact rat renal tissue. Rat renal papillae were prelabeled with 32P and incubated with vehicle or drugs, and then AQP2 was immunoprecipitated. Two polypeptides corresponding to nonglycosylated (29 kDa) and glycosylated (35-48 kDa) AQP2 were identified by SDS-PAGE. AVP caused a time- and dose-dependent increase in phosphorylation of both glycosylated and nonglycosylated AQP2. The threshold dose for a significant increase in phosphorylation was 10 pM, which corresponds to a physiological serum concentration of AVP. Maximal phosphorylation was reached within 1 min of AVP incubation. This effect on AQP2 phosphorylation was mimicked by the vasopressin (V2) agonist, 1-desamino-[8-D-arginine]vasopressin (DDAVP), or forskolin. Two-dimensional phosphopeptide mapping indicated that AVP and forskolin stimulated the phosphorylation of the same site in AQP2. Immunoblot analysis using a phosphorylation state-specific antiserum revealed an increase in phosphorylation of Ser256 after incubation of papillae with AVP. The results indicate that AVP stimulates phosphorylation of AQP2 at Ser256 via activation of PKA, supporting the idea that this is one of the first steps leading to increased water permeability in collecting duct cells.