Effects of reinnervation with normal and tetrodotoxin-inactive nerves on resting membrane potential of rat skeletal muscle

Resting membrane potentials (RMPs) have been recorded in vitro near the end-plate region of rat soleus muscles reinnervated with tetrodotoxin-inactive nerves and compared with those of denervated muscles whose reinnervation had been prevented. The two muscle groups exhibited the same low values of RMP typical of denervated muscles. In control muscles of rats in which impulse conduction was left unimpaired, reinnervation induced the expected increase in RMP values towards normal. It is suggested that, at least for this property, reinnervation restores to normal the muscle fibre membrane essentially through the return of activity.     

Thyrotoxicosis in children: thirty years'experience

Optimal treatment for thyrotoxicosis remains controversial in adults, but more so in paediatric practice. We have conducted a retrospective review of the records of 76 paediatric patients seen between 1965 and 1995 to determine management practice and outcome of therapeutic interventions. Seventeen are currently on antithyroid drug (ATD) treatment, while four have had their care transferred. Of the remaining 55, 21 (38%) achieved long-term remission with ATD alone following a mean treatment duration of 3.3 y (range 0.5-7 y). Block-replacement (high dose of ATD with thyroxine replacement) was more convenient than the titration regimen (3.4+/-0.3 visits to hospital per year versus 6.1+/-0.4, p<0.001). Surgery (subtotal/total thyroidectomy) was carried out in 27 patients, of whom 24 subsequently became hypothyroid and were treated with thyroxine. I131 was used successfully in six patients, two following surgery. ATD should remain the first-line therapy; a block-replacement regimen is more convenient. Surgery in a specialized centre carries a low risk. Caution should still be exercised in the use of I131 in young children.     

Vestibulospinal effects on hindlimb motoneurons of the frog

Summary Field and intracellular potentials were recorded in the lumbar spinal cord of the frog following stimulation of the anterior branch of the vestibular nerve and vestibular nucleus. The field potential recorded in the motoneuron pool after VIIIth nerve stimulation consisted of two presynaptic positive-negative potentials (latencies 1.7 and 2.6 msec) followed by a slow negative wave. The latency of the first presynaptic field potential was only 0.6 msec longer than the presynaptic field potential evoked by stimulation of the vestibular nucleus; it is suggested that electrotonic coupling in the vestibular nuclei is responsible for the fast vestibulospinal transmission.Whereas VIIIth nerve stimulation produced EPSPs in both flexor (peroneal) and extensor (tibial) motoneurons, IPSPs were found only in extensor motoneurons. The functional implication of these findings was discussed. Comparison of PSP latencies with the extracellular presynaptic field potentials generated by VIIIth nerve or nucleus stimulation indicated that EPSPs were produced by the excitatory action of vestibulospinal axons on motoneurons. The longer latencies of the vestibular induced IPSPs suggested that they were generated indirectly by inhibitory spinal interneurons. Preliminary experiments on the interaction of segmental and vestibular induced PSPs suggest that the latter are generated close to the soma of motoneurons.     

Combined use of hyperbaric oxygen and sprayed keratinocyte suspension to tackle a difficult wound

This is the first reported case in the literature to combine the use of a well established therapy to achieve wound healing (ie hyperbaric oxygen treatment) and a novel sprayed keratinocyte suspension technique to treat a challenging wound successfully. The merits and potential issues associated with these treatments are outlined and the case is detailed.     

Recombinant human interleukin-6 induces a rapid and reversible anemia in cancer patients

Initial studies have shown that recombinant human interleukin-6 (rhIL- 6) induces anemia. Until now, the pathophysiologic mechanism of this induced anemia has been unknown. To unravel the underlying mechanism, we examined 15 cancer patients receiving rhIL-6 as an antitumor immunotherapy in a phase II study. rhIL-6 was administered subcutaneously at 150 micrograms once daily for 6 consecutive weeks. Various hematologic and biochemical parameters were measured weekly during rhIL-6 treatment and 4 weeks after rhIL-6 discontinuation. To determine plasma volume and red blood cell (RBC) volume, radioisotope dilution assays with labeled autologous RBCs and with human serum albumin were performed before rhIL-6 administration and on day 8 of rhIL-6 therapy. Hemoglobin levels decreased (mean change +/- SE) 7% +/- 1.5% within 3 days after the start of rhIL-6 therapy (P < .0001) and 19% +/- 2% at week 4. Levels had normalized at follow-up. The plasma volume increased 18% +/- 5% during the first week of rhIL-6 administration (P < .003), whereas RBC volume remained unaffected. The mean RBC corpuscular volume remained unchanged for 2 weeks and then began to decrease slowly, reaching its nadir at week 6 (5% +/- 1%; P < .01). Serum iron levels decreased 65% +/- 12% at week 4 (P < .002) and then returned to initial baseline values. Erythropoietin levels increased rapidly up to 68% at week 3 (P < .0001) and had normalized 4 weeks after rhIL-6 therapy. Levels of serum albumin, prealbumin, and transferrin decreased (P < .0001, P < .003, and P < .0001, respectively), whereas levels of serum amyloid A (P < .003), C-reactive protein, haptoglobin, and alpha-1-antitrypsin (P < .0001) increased during rhIL-6 treatment. All levels returned to pretreatment values after discontinuation of rhIL-6. No alterations in reticulocyte counts, serum lactic dehydrogenase levels, and bilirubin levels were observed. A 6-week regimen of subcutaneous rhIL-6 results in a rapid dilution anemia, caused by an acute and significant increase in plasma volume and followed by hypoferremia. This anemia is reversible after the cessation of rhIL-6 treatment.