Kidney disease appears common in residents of Quezalguaque, Nicaragua, particularly in younger men, with features most consistent with tubulointerstitial disease. Further research is needed to elucidate the causes of kidney disease in this region.

Nicotine permeates into the endoplasmic reticulum (ER) where it begins an “inside-out” pathway that leads to addiction. Shivange et al. develop genetically encoded nicotine biosensors and show that nicotine and varenicline equilibrate in the ER within seconds of extracellular application.

A leucine to alanine substitution (L9ЈA) was introduced in the M2 region of the mouse ␣4 neuronal nicotinic acetylcholine receptor (nAChR) subunit. Expressed in Xenopus oocytes, ␣4(L9ЈA)␤2 nAChRs were Ն30-fold more sensitive than wild type (WT) to both ACh and nicotine. We generated knock-in mice with the L9ЈA mutation and studied their cellular responses, seizure phenotype, and sleepwake cycle. Seizure studies on ␣4-mutated animals are relevant to epilepsy research because all known mutations linked to autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) occur in the M2 region of ␣4 or ␤2 subunits. Thalamic cultures and synaptosomes from L9ЈA mice were hypersensitive to nicotine-induced ion flux. L9ЈA mice were ϳ15-fold more sensitive to seizures elicited by nicotine injection than their WT littermates. Seizures in L9ЈA mice differed qualitatively from those in WT: L9ЈA seizures started earlier, were prevented by nicotine pretreatment, lacked EEG spike-wave discharges, and consisted of fast repetitive movements. Nicotine-induced seizures in L9ЈA mice were partial, whereas WT seizures were generalized. When L9ЈA homozygous mice received a 10 mg/kg nicotine injection, there was temporal and phenomenological separation of mutant and WT-like seizures: an initial seizure ϳ20 s after injection was clonic and showed no EEG changes. A second seizure began 3-4 min after injection, was tonic-clonic, and had EEG spike-wave activity. No spontaneous seizures were detected in L9ЈA mice during chronic video/EEG recordings, but their sleep-wake cycle was altered. Our findings show that hypersensitive ␣4* nicotinic receptors in mice mediate changes in the sleep-wake cycle and nicotineinduced seizures resembling ADNFLE.

The gene defective in cystic fibrosis encodes a C1-channel, the cystic fibrosis transmembrane conductance regulator (CFTR). CFTR is blocked by diphenylamine-2-carboxylate (DPC) when applied extracellularly at millimolar concentrations. We studied the block of CFTR expressed in Xenopus oocytes by DPC or by a closely related molecule, flufenamic acid (FFA). Block of whole-cell CFTR currents by bath-applied DPC or by FFA, both at 200 v,M, requires several minutes to reach full effect. Blockade is voltage dependent, suggesting open-channel block: currents at positive potentials are not affected but currents at negative potentials are reduced. The binding site for both drugs senses ~ 40% of the electric field across the membrane, measured from the inside. In single-channel recordings from excised patches without blockers, the conductance was 8.0 -+ 0.4 pS in symmetric 150 mM CI-. A subconductance state, measuring ~60% of the main conductance, was often observed. Bursts to the full open state lasting up to tens of seconds were uninterrupted at depolarizing membrane voltages. At hyperpolarizing voltages, bursts were interrupted by brief closures. Either DPC or FFA (50 tzM) applied to the cytoplasmic or extracellular face of the channel led to an increase in flicker at I'm = -100 mV and not at Vm = +100 mV, in agreement with whole-cell experiments. DPC induced a higher frequency of flickers from the cytoplasmic side than the extracellular side. FFA produced longer closures than DPC; the FFA closed time was roughly equal (~1.2 ms) at -100 mV with application from either side. In cell-attached patch recordings with DPC or FFA applied to the bath, there was flickery block at Vm = -100 mV, confirming that the drugs permeate through the membrane to reach the binding site. The data are consistent with the presence of a single binding site for both drugs, reached from either end of the channel. Open-channel block by DPC or FFA may offer tools for use with site-directed mutagenesis to describe the permeation pathway.

ART treatment was not a risk factor for adverse perinatal outcome, and risks for several outcomes were somewhat lower among ART twin deliveries. Nonetheless, ART is strongly associated with twinning and twins remain a high-risk group, relative to singletons. Promoting singleton gestation in assisted conception is an important strategy for reducing adverse outcomes.