Altered gating and conductance of Na+ channels in hyperkalemic periodic paralysis

Electrophysiological studies on muscle fibres from patients with hyperkalemic periodic paralysis with myotonia have shown that the episodes of weakness are caused by a sustained depolarization of the sarcolemma to potentials between -40 and -60 mV. In muscle fibre segments from three such patients this sustained depolarization was caused by noninactivating Na⁺ channels with reduced single-channel conductance blocked by TTX and procainamide. As the chloride conductance was normal, myotonia may be best explained with the abnormal reopenings of the Na⁺ channels. The recently described genetic linkage between hyperkalemic periodic paralysis with myotonia and the gene coding for the TTX-sensitive Na⁺ channel suggests an altered primary structure of this channel causing its abnormal function.     

Current concepts and practice in postoperative pain management: need for a change?

Despite a growing trend in acute pain management, many deficiencies still account for the high incidence of moderate to severe postoperative pain to date. Patients nowadays continue to receive inadequate doses of analgesics, but additionally the identification and treatment of those patients with pain still remains a significant health care problem. Advanced techniques are available including epidural or intrathecal administration of local anaesthetics and opioids, various opioid administration techniques such as patient-controlled analgesia and infusions via sublingual, oral-transmucosal, nasal, intra-articular and rectal routes. Nonopioid analgesics such as nonsteroidal anti-inflammatory drugs and newer nonopioid drugs such as alpha2-adrenergic agonists, calcium channel antagonists and various combinations of the above are possible. However, the solution to the problem of inadequate pain relief lies not so much in the development of new drugs and new techniques, but in the effective strategy of delivering these to patients through the introduction of acute pain management services on surgical wards.     

Organization of point contacts in neuronal growth cones

Growth cones from rat dorsal root ganglia plated on laminin contain integrin clusters over the entire growth cone surface, and growth cones make transient adhesions at sites called point contacts. We examined, by immunocytochemistry and confocal microscopy, the composition and distribution of point contacts in neuronal growth cones. Vinculin was concentrated in the central domain of growth cones and at the tips of filopodia. Vinculin was specifically associated with integrin clusters at the membrane-substrate interface and thus marked point contacts. The cytoskeletal proteins paxillin and talin colocalized with beta1 integrin in a subpopulation of clusters restricted to the central domain of the growth cone and to the tips of filopodia. The neuron-specific kinase, FAK+ also distributed with the vinculin-positive clusters. The Rho family proteins RhoA, RhoB, and Cdc42 were present in growth cones, and a few Rho clusters were colocalized with vinculin. Examination of proteins resistant to detergent extraction in PC12 cells confirmed the retention of beta1 integrin, paxillin, talin, and vinculin with the cytoskeleton. Moreover, we detected FAK+ and RhoA in the detergent-resistant cytoskeleton, supporting their distribution to point contacts. Our observations indicate that two types of integrin clusters are present in growth cones: those associated with vinculin at the cell substratum interface, and those not associated with vinculin. Point contacts are mature adhesion sites defined by the presence of both beta1 integrin and vinculin, and they are associated with signaling proteins.     

Sexual and pharmacostimulated erections are proportional

Even complex diagnostic tests may not establish aetiology and degree of erectile dysfunction (ED) in many patients. Therefore, we evaluated a self-report method with a restrictive focus to quality of erections which may yield information sufficient to make an aetiologic diagnosis. We studied 74 patients 25 to 75 years of age with untreated ED. Sexually stimulated erections were quantified and compared to duplexsonographically and clinically evaluated data from pharmacostimulated erections. Patients reported that there was a marked decrease in ability to penetrate the partner, to sustain an erection and of penile rigidity (p < 0.001). Parameters from duplexsonography and clinically assessed response to pharmacostimulation correlated (r = 0.72). Direct comparison of these data with quantified history showed no relation (r = 0.05). Using change in penile volume due to erection as a basis to compare with, showed significant correlation with quantified data from history (r = 0.26-0.34; p < 0.03) and measured parameters from pharmacostimulated erections (r = 0.44-0.55; p < 0.0001). Sexually- and pharmacostimulated erections are proportional to change in penile volume. Although there is a relation between erections emerging from both stimulations, quantifying history on sexually stimulated erections does not qualify to make an aetiologic diagnosis without using complex tests.     

Outbreak of meningococcal disease in western Norway due to a new serogroup C variant of the ET-5 clone: effect of vaccination and selective carriage eradication

A new sulphonamide resistant (SR) C: 15:P1.7,16 meningococcal strain, a variant of the ET-5 clone, dominated in an outbreak of 22 cases in western Norway commencing in 1995. The first eight patients were 15-21 years old from the Nordhordland area, initiating a carrier study in the local high schools. Carriage of SR serogroup C meningococci was detected by routine methods and treated with a single dose of ofloxacin 400 mg. Of 20 treated carriers, 14 harboured the outbreak strain C: 15:P1.7,16. Vaccination of 4000 children, adolescents and close contacts of patients was also performed. After the intervention, 14 additional cases of meningococcal disease occurred, 8 due to the outbreak strain. However, incidence rates dropped from 180 to 30 per 100000 per year in the student population, but increased from 0 to 13 in the rest of the population in Nordhordland. Carriage eradication is not generally recommended in Norway. However, tracing and treating meningococcal carriage may have reduced transmission and disease in this outbreak situation.