Reduced Expression of TMEM16A Impairs Nitric Oxide-Dependent Cl- Transport in Retinal Amacrine Cells.

Postsynaptic cytosolic Cl- concentration determines whether GABAergic and glycinergic synapses are inhibitory or excitatory. We have shown that nitric oxide (NO) initiates the release of Cl- from acidic internal stores into the cytosol of retinal amacrine cells (ACs) thereby elevating cytosolic Cl-. In addition, we found that cystic fibrosis transmembrane conductance regulator (CFTR) expression and Ca2+ elevations are necessary for the transient effects of NO on cytosolic Cl- levels, but the mechanism remains to be elucidated. Here, we investigated the involvement of TMEM16A as a possible link between Ca2+ elevations and cytosolic Cl- release. TMEM16A is a Ca2+-activated Cl- channel that is functionally coupled with CFTR in epithelia. Both proteins are also expressed in neurons. Based on this and its Ca2+ dependence, we test the hypothesis that TMEM16A participates in the NO-dependent elevation in cytosolic Cl- in ACs. Chick retina ACs express TMEM16A as shown by Western blot analysis, single-cell PCR, and immunocytochemistry. Electrophysiology experiments demonstrate that TMEM16A functions in amacrine cells. Pharmacological inhibition of TMEM16A with T16inh-AO1 reduces the NO-dependent Cl- release as indicated by the diminished shift in the reversal potential of GABAA receptor-mediated currents. We confirmed the involvement of TMEM16A in the NO-dependent Cl- release using CRISPR/Cas9 knockdown of TMEM16A. Two different modalities targeting the gene for TMEM16A (ANO1) were tested in retinal amacrine cells: an all-in-one plasmid vector and crRNA/tracrRNA/Cas9 ribonucleoprotein. The all-in-one CRISPR/Cas9 modality did not change the expression of TMEM16A protein and produced no change in the response to NO. However, TMEM16A-specific crRNA/tracrRNA/Cas9 ribonucleoprotein effectively reduces both TMEM16A protein levels and the NO-dependent shift in the reversal potential of GABA-gated currents. These results show that TMEM16A plays a role in the NO-dependent Cl- release from retinal ACs.

Knowledge and Needs of Resident Physicians Regarding Osteoporosis: A Nationwide Survey of Residents.

Large-scale studies have not addressed the knowledge level of US resident physicians regarding osteoporosis management. We gauged the knowledge level of family medicine, internal medicine, and obstetrics and gynecology resident physicians regarding osteoporosis management. In 2019, we sent an anonymous survey via e-mail to all program directors of Accreditation Council for Graduate Medical Education-accredited residency programs in family medicine, internal medicine, and obstetrics and gynecology for distribution to resident physicians. Knowledge items assessed osteoporosis screening, diagnosis, and treatment. We received responses from 182 family medicine, 275 internal medicine, and 122 obstetrics and gynecology programs. Of 582 resident physician respondents, 31% were family medicine residents, 47% were internal medicine residents, and 21% were obstetrics and gynecology residents. Although 77% of respondents correctly selected the T-score threshold for the diagnosis of osteoporosis among persons aged 50 years and older (-2.5), only 20% of respondents correctly identified minimal-trauma hip fracture as being diagnostic of osteoporosis. One-third of respondents correctly identified which medications were demonstrated in clinical trials to decrease hip fracture risk. Fifteen percent of respondents correctly identified that denosumab and alendronate are associated with osteonecrosis of the jaw; and 40% of respondents correctly identified that decline in bone density is more rapid after discontinuation of denosumab than after discontinuation of bisphosphonates. Less than half of resident physicians knew that bisphosphonate-associated atypical femoral fractures are duration-dependent. One-quarter of respondents felt not at all prepared to manage osteoporosis. In this nationwide survey of resident physicians, knowledge regarding osteoporosis diagnosis and treatment was poor, with a striking lack of knowledge regarding the two most serious adverse effects of osteoporosis pharmacotherapy (osteonecrosis of the jaw and atypical femoral fractures). The undertreatment of osteoporosis is unlikely to improve without increased education of resident physicians. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

A pilot study of stored low titer group O whole blood + component therapy versus component therapy only for civilian trauma patients.

BACKGROUND: This pilot assessed transfusion requirements during resuscitation with whole blood followed by standard component therapy (CT) versus CT alone, during a change in practice at a large urban Level I trauma center. METHODS: This was a single-center prospective cohort pilot study. Male trauma patients received up to 4 units of cold-stored low anti-A, anti-B group O whole blood (LTOWB) as initial resuscitation followed by CT as needed (LTOWB + CT). A control group consisting of women and men who presented when LTOWB was unavailable, received CT only (CT group). Exclusion criteria included antiplatelet or anticoagulant medication and death within 24 hours. The primary outcome was total transfusion volume at 24 hours. Secondary outcomes were mortality, morbidity, and intensive care unit- and hospital-free days. RESULTS: Thirty-eight patients received LTOWB, with a median of 2.0 (interquartile range [IQR] 1.0-3.0) units of LTOWB transfused. Thirty-two patients received CT only. At 24 hours after presentation, the LTOWB +CT group had received a median of 2,138 mL (IQR, 1,275-3,325 mL) of all blood products. The median for the CT group was 4,225 mL (IQR, 1,900-5,425 mL; p = 0.06) in unadjusted analysis. When adjusted for Injury Severity Score, sex, and positive Focused Assessment with Sonography for Trauma, LTOWB +CT group patients received 3307 mL of blood products, and CT group patients received 3,260 mL in the first 24 hours (p = 0.95). The adjusted median ratio of plasma to red cells transfused was higher in the LTOWB + CT group (0.85 vs. 0.63 at 24 hours after admission; p = 0.043. Adjusted mortality was 4.4% in the LTOWB + CT group, and 11.7% in the CT group (p = 0.19), with similar complications, intensive care unit-, and hospital-free days in both groups. CONCLUSION: Beginning resuscitation with LTOWB results in equivalent outcomes compared with resuscitation with CT only. LEVEL OF EVIDENCE: Therapeutic (Prospective study with 1 negative criterion, limited control of confounding factors), level III.

A role for the cystic fibrosis transmembrane conductance regulator in the nitric oxide-dependent release of Cl- from acidic organelles in amacrine cells.

γ-Amino butyric acid (GABA) and glycine typically mediate synaptic inhibition because their ligand-gated ion channels support the influx of Cl- However, the electrochemical gradient for Cl- across the postsynaptic plasma membrane determines the voltage response of the postsynaptic cell. Typically, low cytosolic Cl- levels support inhibition, whereas higher levels of cytosolic Cl- can suppress inhibition or promote depolarization. We previously reported that nitric oxide (NO) releases Cl- from acidic organelles and transiently elevates cytosolic Cl-, making the response to GABA and glycine excitatory. In this study, we test the hypothesis that the cystic fibrosis transmembrane conductance regulator (CFTR) is involved in the NO-dependent efflux of organellar Cl- We first establish the mRNA and protein expression of CFTR in our model system, cultured chick retinal amacrine cells. Using whole cell voltage-clamp recordings of currents through GABA-gated Cl- channels, we examine the effects of pharmacological inhibition of CFTR on the NO-dependent release of internal Cl- To interfere with the expression of CFTR, we used clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 genome editing. We find that both pharmacological inhibition and CRISPR/Cas9-mediated knockdown of CFTR block the ability of NO to release Cl- from internal stores. These results demonstrate that CFTR is required for the NO-dependent efflux of Cl- from acidic organelles.NEW & NOTEWORTHY Although CFTR function has been studied extensively in the context of epithelia, relatively little is known about its function in neurons. We show that CFTR is involved in an NO-dependent release of Cl- from acidic organelles. This internal function of CFTR is particularly relevant to neuronal physiology because postsynaptic cytosolic Cl- levels determine the outcome of GABA- and glycinergic synaptic signaling. Thus the CFTR may play a role in regulating synaptic transmission.