Pacemaker activity of spontaneously active neurons and heart cells is controlled by a depolarizing, mixed Na+/K+ current, named Ih (or I(f) in the sinoatrial node of the heart). This current is activated on hyperpolarization of the plasma membrane. In addition to depolarizing pacemaker cells, Ih is involved in determining the resting membrane potential of neurons and provides a mechanism to limit hyperpolarizing currents in these cells. Hormones and neurotransmitters that induce a rise in cyclic AMP levels increase Ih by a mechanism that is independent of protein phosphorylation, and which involves direct binding of the cyclic nucleotide to the channel that mediates Ih. Here we report the molecular cloning and functional expression of the gene encoding a hyperpolarization-activated cation channel (HAC1) that is present in brain and heart. This channel exhibits the general properties of Ih channels. We have also identified full-length sequences of two related channels, HAC2 and HAC3, that are specifically expressed in the brain, indicating the existence of a family of hyperpolarization-activated cation channels.

Background Data are lacking on the relative incidence of thrombotic thrombocytopenic purpura (TTP), haemolytic uraemic syndrome (HUS) caused by Shiga toxin–producing Escherichia coli (STEC) and atypical HUS (aHUS) in patients presenting with thrombotic microangiopathies (TMAs). Methods This was a prospective, cross-sectional, multicentre and non-interventional epidemiological study. Patients fulfilling criteria for TMAs (platelet consumption, microangiopathic haemolytic anaemia and organ dysfunction) were included in the study. The primary objective was to assess the relative incidence of TTP, STEC-HUS, aHUS and ‘other’ physician-defined diagnoses. The secondary objective was to develop an algorithm to predict a severe deficiency in ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) activity (≤10%) using routine laboratory parameters. A post hoc classification using the recent Kidney Disease: Improving Global Outcomes diagnostic criteria was then undertaken to further classify patient groups. Results aHUS was diagnosed with a relative incidence of 61%, whereas TTP, STEC-HUS and ‘other’ were diagnosed in 13, 6 and 20% of patients, respectively. In the post hoc analysis, 27% of patients with a TMA were classified as ‘primary aHUS’ and 53% as ‘secondary aHUS’. Multivariate analysis revealed that severe deficiency in ADAMTS13 activity (≤10%) was unlikely to underlie TMA if platelet and serum creatinine were above threshold values of 30 × 109/L and 1.8 mg/dL, respectively (negative predictive value of 92.3 and 98.1, respectively, if one or both values were above the threshold). Conclusions In this study, aHUS was the most common single diagnosis among patients presenting with a TMA. In the absence of an ADAMTS13 activity result, platelet count and serum creatinine may aid in the differential diagnosis.

Risedronate 150 mg once monthly has demonstrated less reduction of BTM and non-inferior BMD gains versus daily, whereas 150 mg once monthly ibandronate has demonstrated BTM suppression within the premenopausal range and BMD gains superior to the daily regimen. Furthermore, ibandronate has demonstrated antifracture efficacy with intermittent dosing in two pooled analyses. Risedronate has yet to demonstrate anti-fracture efficacy with an extended (intermittent) dosing regimen.

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