Articles: cations.
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Neurochemical research · Jan 2004
Electroneutral cation-chloride cotransporters in the central nervous system.
Several members of the cation-chloride cotransporter (solute carrier family 12, SLC12) gene family are expressed within the central nervous system, with one family member, the K+-Cl- cotransporter KCC2, exclusive to neurons. These transporters are best known for their roles in cell volume regulation and epithelial salt transport, but are increasingly receiving attention in neuroscience. ⋯ This relationship has important implications for neuronal development, sensory perception, neuronal excitability, and the response to neuronal injury. Finally, the association between loss of function in the K+-Cl- cotransporter KCC3, with a severe peripheral neuropathy associated with agenesis of the corpus callosum, has revealed an unexpected role for K+-Cl- cotransport in the development and/or maintenance of both the central and peripheral nervous systems.
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Comparative Study
Pre- and post-synaptic effects of manipulating surface charge with divalent cations at the photoreceptor synapse.
Persistence of horizontal cell (HC) light responses in extracellular solutions containing low Ca2+ plus divalent cations to block Ca2+ currents (ICa) has been attributed to Ca2+-independent neurotransmission. Using a retinal slice preparation to record both ICa and light responses, we demonstrate that persistence of HC responses in low [Ca2+]o can instead be explained by a paradoxical increase of Ca2+ influx into photoreceptor terminals arising from surface charge-mediated shifts in ICa activation. Consistent with this explanation, application of Zn2+ or Ni2+ caused a hyperpolarizing block of HC light responses that was relieved by lowering [Ca2+]o. ⋯ Nominally divalent-free media produced inversion of HC light responses even though rod light responses remained hyperpolarizing; HC response inversion can be explained by surface charge-mediated shifts in ICa. In summary, HC light responses modifications induced by low divalent cation solutions can be explained by effects on photoreceptor light responses and membrane surface charge without necessitating Ca2+-independent neurotransmission. Furthermore, these results suggest that surface charge effects accompanying physiological changing divalent cation levels in the synaptic cleft may provide a means for modulating synaptic output from photoreceptors.
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Postoperative vomiting remains a common complication of general anesthesia and occurs more frequently in children than adults. Prophylactic antiemetics have limited efficacy and have a potential for side effects. The new 5 HT3 antagonists are effective but expensive, while the older less expensive drugs such as droperidol have come under disrepute because of the potential for serious, life-threatening, cardiac arrhythmias. This review examines the literature to aid practicing anesthesiologists in the choice of patient who will benefit from prophylactic antiemetics. ⋯ Anesthesiologists should practice evidence-based medicine in reducing the common anesthetic complication of postoperative vomiting by an individualized approach that balances the choice of drugs with the expected risk of postoperative vomiting for cost-effective management.
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Skull Base Interd Ap · Nov 2003
Submental Orotracheal Intubation: An Alternative to Tracheotomy in Transfacial Cranial Base Surgery.
This retrospective study evaluated the safety and efficacy of submental intubation not only for trauma treatment but also for oncological cranial base surgery. The medical records of 24 patients who underwent submental intubation from 1996 to 2002 were reviewed. There were 6 procedures for craniofacial trauma, 12 transmaxillary approaches to the clivus for clivus chordomas, and 6 transmaxillary approaches to the cranial base for chondrosarcomas. ⋯ It avoids the complications associated with tracheostomy. It also permits considerable downward retraction of the maxilla after a Le Fort I osteotomy and is associated with good clival exposure. Furthermore, it does not interfere with maxillomandibular fixation at the end of the surgery.
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Migraine is a common, chronic neurologic disorder that affects approximately 12% of the adult population in Western countries. Once migraine is diagnosed, illness severity must be assessed. Clinicians and patients should then work together to develop a treatment plan based on patient needs and preferences. ⋯ A variety of behavioral interventions are helpful. The clinician has an armamentarium of ever-expanding variety of medications. With experience, clinicians can match individual patient needs with the specific characteristics of a drug to optimize therapeutic benefit.