Clinical outcomes and prognostic factors after HCV clearance with DAA in HIV/HCV-coinfected patients with advanced fibrosis/cirrhosis.

BACKGROUND AND AIMS: We assessed long-term clinical outcomes and prognostic factors for liver disease progression after sustained viral response with direct-acting antivirals in patients coinfected with HIV/HCV with advanced fibrosis or cirrhosis. APPROACH AND RESULTS: A total of 1300 patients who achieved sustained viral response with direct-acting antivirals from 2014 to 2017 in Spain were included: 1145 with compensated advanced chronic liver disease (384 advanced fibrosis and 761 compensated cirrhosis) and 155 with decompensated cirrhosis. The median follow-up was 40.9 months. Overall, 85 deaths occurred, 61 due to non-liver non-AIDS-related causes that were the leading cause of death across all stages of liver disease. The incidence (95% CI) of decompensation per 100 person-years (py) was 0 in patients with advanced fibrosis, 1.01 (0.68-1.51) in patients with compensated cirrhosis, and 8.35 (6.05-11.53) in patients with decompensated cirrhosis. The incidence (95% CI) of HCC per 100 py was 0.34 (0.13-0.91) in patients with advanced fibrosis, 0.73 (0.45-1.18) in patients with compensated cirrhosis, and 1.92 (1.00-3.70) per 100 py in patients with decompensated cirrhosis. Prognostic factors for decompensation in patients with compensated advanced chronic liver disease included serum albumin, liver stiffness measurement (LSM), and fibrosis 4. In this population, LSM and LSM-based posttreatment risk stratification models showed their predictive ability for decompensation and HCC. CONCLUSIONS: Non-liver non-AIDS-related events were the leading causes of morbidity and mortality after direct-acting antiviral cure among coinfected patients with advanced fibrosis/cirrhosis. Among those with compensated advanced chronic liver disease, baseline LSM and posttreatment LSM-based models helped to assess decompensation and HCC risk.

Tenofovir Disoproxil Fumarate/Emtricitabine and Baricitinib for Patients at High Risk of Severe Coronavirus Disease 2019: The PANCOVID Randomized Clinical Trial.

BACKGROUND: This study was designed to evaluate if patients with high risk for severe coronavirus disease 2019 (COVID-19) would benefit from treatment with tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) followed by baricitinib in case of hypoxemia and systemic inflammation. METHODS: PANCOVID is an open-label, double-randomized, phase 3 pragmatic clinical trial including adults with symptomatic COVID-19 with ≥2 comorbidities or aged ≥60 years and was conducted between 10 October 2020 and 23 September 2021. In the first randomization, patients received TDF/FTC or no TDF/FTC. In the second randomization, patients with room air oxygen saturation <95% and at least 1 increased inflammatory biomarker received baricitinib plus dexamethasone or dexamethasone alone. The primary endpoint was 28-day mortality. Main secondary endpoint was 28-day disease progression or critical care unit admission or mortality. The trial was stopped before reaching planned sample size due to the decrease in the number of cases and a mortality rate substantially lower than expected. RESULTS: Of the 355 included participants, 97% were hospitalized at baseline. Overall, 28-day mortality was 3.1%. The 28-day mortality relative risk (RR) for participants treated with TDF/FTC was 1.76 (95% confidence interval [CI], .52-5.91; P = .379); it was 0.42 (95% CI, .11-1.59; P = .201) for those treated with baricitinib. The 28-day RR for the main secondary combined endpoint for participants treated with TDF/FTC was 0.95 (95% CI, .66-1.40; P = .774); it was 0.90 (95% CI, .61-1.33; P = .687) for those treated with baricitinib. CONCLUSIONS: Our results do not suggest a beneficial effect of TDF/FTC; nevertheless, they are compatible with the beneficial effect of baricitinib already established by other clinical trials. CLINICAL TRIALS REGISTRATION: EudraCT: 2020-001156-18.

Epidemiological trends of HIV/HCV coinfection in Spain, 2015-2019.

OBJECTIVES: We assessed the prevalence of anti-hepatitis C virus (HCV) antibodies and active HCV infection (HCV-RNA-positive) in people living with HIV (PLWH) in Spain in 2019 and compared the results with those of four similar studies performed during 2015-2018. METHODS: The study was performed in 41 centres. Sample size was estimated for an accuracy of 1%. Patients were selected by random sampling with proportional allocation. RESULTS: The reference population comprised 41 973 PLWH, and the sample size was 1325. HCV serostatus was known in 1316 PLWH (99.3%), of whom 376 (28.6%) were HCV antibody (Ab)-positive (78.7% were prior injection drug users); 29 were HCV-RNA-positive (2.2%). Of the 29 HCV-RNA-positive PLWH, infection was chronic in 24, it was acute/recent in one, and it was of unknown duration in four. Cirrhosis was present in 71 (5.4%) PLWH overall, three (10.3%) HCV-RNA-positive patients and 68 (23.4%) of those who cleared HCV after anti-HCV therapy (p = 0.04). The prevalence of anti-HCV antibodies decreased steadily from 37.7% in 2015 to 28.6% in 2019 (p < 0.001); the prevalence of active HCV infection decreased from 22.1% in 2015 to 2.2% in 2019 (p < 0.001). Uptake of anti-HCV treatment increased from 53.9% in 2015 to 95.0% in 2019 (p < 0.001). CONCLUSIONS: In Spain, the prevalence of active HCV infection among PLWH at the end of 2019 was 2.2%, i.e. 90.0% lower than in 2015. Increased exposure to DAAs was probably the main reason for this sharp reduction. Despite the high coverage of treatment with direct-acting antiviral agents, HCV-related cirrhosis remains significant in this population.

HIV/HBV coinfection: temporal trends and patient characteristics, Spain, 2002 to 2018.

BackgroundRecent and reliable estimates on the prevalence of coinfection with human immunodeficiency virus (HIV) and hepatitis B virus (HBV) in Europe are lacking.AimLeveraged on a study designed to assess HIV/HCV coinfection prevalence, we assessed the prevalence of HIV/HBV coinfection in Spain in 2018 and compared the results with five similar studies performed since 2002.MethodsThis cross-sectional prevalence study was carried out in 43 centres, and patients were selected using simple random sampling. The reference population comprised 40,322 patients and the sample size were 1,690 patients.ResultsThe prevalence of HIV/HBV coinfection in Spain at the end of 2018 was 3.2%. The prevalence in 2002, 2009, 2015, 2016 and 2017 was 4.9%, 3.4%, 3%, 3.9% and 3%, respectively. Among the HIV/HBV-coinfected patients identified in 2018, 16.7% had cirrhosis according to transient elastography and 26.3% tested positive for antibodies against hepatitis D virus. All HIV/HBV-coinfected patients were receiving drugs with activity against HBV, and 97% of those tested for HBV DNA had an HBV DNA load < 80 IU/mL.ConclusionsThe prevalence of HIV/HBV coinfection in Spain remained stable at around 3% for a decade. Our data could facilitate the design of national programmes to control HBV infection and help identify areas of patient management that need improvement.

[Translated article] Implementation of a traceability and safe drug preparation system in a clean room.

OBJECTIVE: To describe the process of implementing a traceability and safe manufacturing system in the clean room of a pharmacy service to increase patient safety, in accordance with current legislation. METHODS: The process was carried out between September 2021 and July 2022. The software program integrated all the recommended stages of the manufacturing process outlined in the "Good Practices Guide for Medication Preparation in Pharmacy Services" (GBPP). The following sections were parameterised in the software program: personnel, facilities, equipment, starting materials, packaging materials, standardised work procedures, and quality controls. RESULTS: A total of 50 users, 4 elaboration areas and 113 equipments were included. 435 components were parameterized (195 raw materials and 240 pharmaceutical specialties), 54 packaging materials, 376 standardised work procedures (123 of them corresponding to sterile medicines and 253 to non-sterile medicines, of which 52 non-sterile were dangerous), in addition, 17 were high risk, 327 medium risk, and 32 low risk, and 13 quality controls. CONCLUSIONS: The computerization of the production process has allowed the implementation of a traceability and secure manufacturing system in a controlled environment in accordance with current legislation.

Implementation of a traceability system and safe manufacturing medications in a clean room. / Implantación de un sistema de trazabilidad y elaboración segura de medicamentos en la sala blanca.

OBJECTIVE: To describe the process of implementing a traceability and safe drug manufacturing system in the clean room of a Pharmacy Service to increase patient safety, in accordance with current legislation. METHODS: The process was carried out between September 2021 and July 2022. The software program integrated all the recommended stages of the manufacturing process outlined in the "Good Practices Guide for Medication Preparation in Pharmacy Services" (GBPP). The following sections were parameterized in the software program: personnel, facilities, equipment, starting materials, packaging materials, standardized work procedures, and quality controls. RESULTS: A total of 50 users, 4 elaboration areas and 113 equipments were included. 435 components were parameterized (195 raw materials and 240 pharmaceutical specialties), 54 packaging materials, 376 standardized work procedures (123 of them corresponding to sterile medicines and 253 to non-sterile medicines, of which 52 non-sterile were dangerous), in addition 17 were high risk, 327 medium risk, 32 low risk, and 13 quality controls. CONCLUSIONS: The computerization of the production process has allowed the implementation of a traceability and secure drug manufacturing system in a controlled environment in accordance with current legislation.

Prospective study for the early detection of lung carcinoma in patients with HIV infection (GESIDA study 8815).

INTRODUCTION: Lung cancer (LC) screening detects tumors early. The prospective GESIDA 8815 study was designed to assess the usefulness of this strategy in HIV + people (PLHIV) by performing a low-radiation computed tomography (CT) scan. PATIENTS AND METHODS: 371 heavy smokers patients were included (>20 packs/year), >45 years old and with a CD4+ <200 mm3 nadir. One visit and CT scan were performed at baseline and 4 for follow-up time annually. RESULTS: 329 patients underwent the baseline visit and CT (CT0) and 206 completed the study (CT1 = 285; CT2 = 259; CT3 = 232; CT4 = 206). All were receiving ART. A total >8 mm lung nodules were detected, and 9 early-stage PCs were diagnosed (4 on CT1, 2 on CT2, 1 on CT3 and 2 on CT4). There were no differences between those who developed LC and those who did not in sex, age, CD4+ nadir, previous lung disease, family history, or amount of packets/year. At each visit, other pathologies were diagnosed, mainly COPD, calcified coronary artery and residual tuberculosis lesions. At the end of the study, 38 patients quit smoking and 75 reduced their consumption. Two patients died from LC and 16 from other causes (p = 0.025). CONCLUSIONS: The design of the present study did not allow us to define the real usefulness of the strategy. Adherence to the test progressively decreased over time. The diagnosis of other thoracic pathologies is very frequent. Including smokers in an early diagnosis protocol for LC could help to quit smoking.

Management of prediabetes from the perspective of Spanish physicians and community pharmacists: Detecta2 study.

INTRODUCTION: Prediabetes is a high-risk state for diabetes. The study aims to describe routine clinical practice and the views of physicians and pharmacists on prediabetes management. MATERIALS AND METHODS: An observational, descriptive, cross-sectional study was conducted using a structured questionnaire. RESULTS: A total of 410 physicians and 393 pharmacists completed the questionnaire. Self-adherence to clinical practice guidelines (CPGs) was reported by 51.5% and 23.2% of physicians and pharmacists, respectively. Less than 60% of participants defined prediabetes according to main CPG. Regarding the use of screening strategies to detect prediabetes (physicians: 96%; pharmacists: 42.1%), reports indicate the opportunistic strategy is widely employed (≥75%) whereas systematic screening is unusual (<20%). Changes in lifestyle were deemed essential by almost all participants (≥95%), but in clinical practice only 58.3% of healthcare centers and 28.0% of pharmacies were found to provide awareness-raising/instruction. The role of pharmacists in the prevention of prediabetes/diabetes was judged useful by most participants. CONCLUSIONS: Use of CPG, systematic prediabetes screening strategies, and specific strategies for patient education are scarce. The support of community pharmacists in prediabetes management was well valued. Therefore, it is crucial that the lines of action followed by both physicians and pharmacists align with each other and with the CPG.

Management of prediabetes from the perspective of Spanish physicians and community pharmacists: Detecta2 study.

INTRODUCTION: Prediabetes is a high-risk state for diabetes. The study aims to describe routine clinical practice and the views of physicians and pharmacists on prediabetes management. MATERIALS AND METHODS: An observational, descriptive, cross-sectional study was conducted using a structured questionnaire. RESULTS: A total of 410 physicians and 393 pharmacists completed the questionnaire. Self-adherence to clinical practice guidelines (CPGs) was reported by 51.5% and 23.2% of physicians and pharmacists, respectively. Less than 60% of participants defined prediabetes according to main CPG. Regarding the use of screening strategies to detect prediabetes (physicians: 96%; pharmacists: 42.1%), reports indicate the opportunistic strategy is widely employed (≥75%) whereas systematic screening is unusual (<20%). Changes in lifestyle were deemed essential by almost all participants (≥95%), but in clinical practice only 58.3% of healthcare centers and 28.0% of pharmacies were found to provide awareness-raising/instruction. The role of pharmacists in the prevention of prediabetes/diabetes was judged useful by most participants. CONCLUSIONS: Use of CPG, systematic prediabetes screening strategies, and specific strategies for patient education are scarce. The support of community pharmacists in prediabetes management was well valued. Therefore, it is crucial that the lines of action followed by both physicians and pharmacists align with each other and with the CPG.

Management of atherogenic dyslipidemia in the primary care setting in Spain.

AIM: To describe the management of atherogenic dyslipidemia (AD) in routine clinical practice in the Primary Care (PC) setting in Spain. METHODS: Observational, descriptive, cross-sectional study based on a structured questionnaire designed for this study and addressed to PC physicians. The questionnaire content was based on a literature review and was validated by 3 experts in AD. RESULTS: A total of 1029 PC physicians participated in the study. 96.99% indicated that AD is determinant for cardiovascular risk, even if LDL-C levels are appropriate. 88.43% evaluated residual cardiovascular risk in their clinical practice, however, only 27.89% of them evaluated it in secondary prevention. Regarding diagnosis, 82.22% reported that TC, TG, HDL-C and non-HDL-C are essential measures when evaluating AD. Almost all physicians reported that they can request fractionated cholesterol to assess HDL-C and LDL-C, however 3.69% could not. Physicians (95.63%) considered that the first step in AD treatment should be diet, regular exercise, smoking cessation and pharmaceutical treatment, if necessary. 19.1% agreed partially or completely that gemfibrozil is the most suitable fibrate to associate with statins. 74.83% completely agreed that fenofibrate is the most suitable fibrate to combine with statins. CONCLUSIONS: Physicians have access to general Spanish guidelines and recommendations associated with AD management, however, it is necessary to continue rising awareness about the importance of early detection and optimal control of AD to reduce patients' cardiovascular risk.

Physicians' and Pharmacists' Clinical Considerations for Elderly Patients with Type 2 Diabetes Mellitus: The IMPLICA2 Study.

BACKGROUND: Management of elderly patients with type 2 diabetes mellitus (T2DM) is complex due to their age-related conditions. Several clinical guidelines provide specific recommendations for management of these patients but little is known about their implementation in clinical practice. OBJECTIVE: To describe physician and community pharmacist perceptions and routine clinical practice in the management of elderly T2DM patients. METHODS: Cross-sectional study. RESULTS: A total of 993 physicians and 999 community pharmacists completed the questionnaire. More physicians than pharmacists agreed on the need to establish more flexible HbA1c targets for elderly (79.4% vs. 30.6%; p < 0.001) and frail (92.6% vs. 31.4%; p < 0.001) patients than for the general diabetic population. HbA1c targets < 7.5% for elderly patients and < 8.5% for frail patients (as recommended by the principle guidelines) were set by 38.9% and 28.7% of physicians, respectively. Furthermore, 62.8% of physicians stated they follow guideline recommendations but, based on their prescription decisions for hypothetical patients, less than 50% were aligned with them. In addition, 73.1% of physicians monitor treatment adherence, mainly by using dispensing control (59.1%). Specific nutritional approaches for elderly patients are provided by 62.9% of physicians and 56.0% of pharmacists, whilst 57.4% and 21.7%, respectively, deliver specific physical exercise programs. CONCLUSIONS: Low adherence to guideline recommendations (i.e. setting more stringent HbA1c targets or delaying treatment intensification) may lead to suboptimal glycaemic control in elderly patients. The standardization of processes, extensive monitoring of patient treatment adherence and providing advice regarding specific personal lifestyle habits may improve the management of elderly T2DM patients.

The application of atherogenic dyslipidaemia consensus recommendations in the primary care setting. DAT-AP study.

BACKGROUND AND AIMS: The "DAT-AP" (from the Spanish, "Dislipemia ATerogénica en Atención Primaria", for Atherogenic Dyslipidaemia in Primary Care) study objective is to determine to what extent published consensus guidelines for the diagnostic and therapeutic management of AD are used in the primary care setting, and to evaluate the approach of the participating physicians towards the detection, diagnosis, and treatment of AD. METHODS: This is descriptive, cross-sectional, multicentre study performed between January and May 2015 in primary care centres throughout Spain. Study data were collected in 2 independent blocks, the first addressing theoretical aspects of AD and the second, practical aspects (clinical cases) RESULTS: The theoretical part is in the process of publication. This manuscript depicts the clinical cases block. Although study participants showed good knowledge of the subject, the high prevalence of this disease requires an additional effort to optimise detection and treatment, with the implementation of appropriate lifestyle interventions and the prescription of the best treatment.

Medication adherence and persistence in type 2 diabetes mellitus: perspectives of patients, physicians and pharmacists on the Spanish health care system.

OBJECTIVE: A good relationship between diabetes patients and their health care team is crucial to ensure patients' medication adherence and self-management. To this end, we aimed to identify and compare the views of type 2 diabetes mellitus (T2DM) patients, physicians and pharmacists concerning the factors and strategies that may be associated with, or could improve, medication adherence and persistence. METHODS: An observational, cross-sectional study was conducted using an electronic self-administered questionnaire comprising 11 questions (5-point Likert scale) concerning factors and strategies related to medication adherence. The survey was designed for T2DM patients and Spanish National Health System professionals. RESULTS: A total of 963 T2DM patients, 998 physicians and 419 pharmacists participated in the study. Overall, a lower proportion of pharmacists considered the proposed factors associated with medication adherence important as compared to patients and physicians. It should be noted that a higher percentage of physicians in comparison to pharmacists perceived that "complexity of medication" (97% vs 76.6%, respectively) and "adverse events" (97.5% vs 72.2%, respectively) were important medication-related factors affecting adherence. In addition, both patients (80.8%) and physicians (80.8%) agreed on the importance of "cost and co-payment" for adherence, whereas only 48.6% of pharmacists considered this factor important. It is also noteworthy that nearly half of patients (43%) agreed that "to adjust medication to activities of daily living" was the best strategy to reduce therapeutic complexity, whereas physicians believed that "reducing the frequency of administration" (47.9%) followed by "reducing the number of tablets" (28.5%) was the most effective strategy to improve patients' adherence. CONCLUSION: Our results highlight the need for pharmacists to build a stronger relationship with physicians in order to improve patients monitoring and adherence rates. Additionally, these findings may help to incorporate greater patient-centeredness when developing management strategies, focusing on adjusting medication regimens to patients' daily lives.

Management of atherogenic dyslipidemia in the primary care setting in Spain / Manejo de la dislipemia aterogénica en el ámbito de Atención Primaria en España

Aim: To describe the management of atherogenic dyslipidemia (AD) in routine clinical practice in the Primary Care (PC) setting in Spain. Methods: Observational, descriptive, cross-sectional study based on a structured questionnaire designed for this study and addressed to PC physicians. The questionnaire content was based on a literature review and was validated by 3 experts in AD. Results: A total of 1029 PC physicians participated in the study. 96.99% indicated that AD is determinant for cardiovascular risk, even if LDL-C levels are appropriate. 88.43% evaluated residual cardiovascular risk in their clinical practice, however, only 27.89% of them evaluated it in secondary prevention. Regarding diagnosis, 82.22% reported that TC, TG, HDL-C and non-HDL-C are essential measures when evaluating AD. Almost all physicians reported that they can request fractionated cholesterol to assess HDL-C and LDL-C, however 3.69% could not. Physicians (95.63%) considered that the first step in AD treatment should be diet, regular exercise, smoking cessation and pharmaceutical treatment, if necessary. 19.1% agreed partially or completely that gemfibrozil is the most suitable fibrate to associate with statins. 74.83% completely agreed that fenofibrate is the most suitable fibrate to combine with statins. Conclusions: Physicians have access to general Spanish guidelines and recommendations associated with AD management, however, it is necessary to continue rising awareness about the importance of early detection and optimal control of AD to reduce patients' cardiovascular risk

Objetivo: Describir el manejo de la dislipemia aterogénica (DA) en la práctica clínica, en el ámbito de la atención primaria (AP) en España. Métodos: Estudio observacional, descriptivo y transversal, por medio de un cuestionario ad-hoc estructurado, dirigido a médicos de AP. El contenido del cuestionario se basó en una revisión de la literatura y fue validado por 3 expertos en DA. Resultados: Participaron en el estudio 1.029 médicos de AP. El 96,99% coincidió en que la DA constituye un factor determinante del riesgo cardiovascular aunque los niveles de cLDL sean adecuados. Un 88,43% indicó que evaluaba el riesgo residual cardiovascular en su práctica clínica habitual, aunque un 27,89% lo evaluaba solo en prevención secundaria. Un 82,22% consideró que para la valoración de un paciente con DA es imprescindible conocer el colesterol total, los triglicéridos, el cHDL, el cLDL y el no-cHDL. La mayoría indicó que podía solicitar fraccionamiento del colesterol total para valorar el cHDL y el cLDL, de forma rutinaria sin restricciones, pero el 3,69% indicó que no. Un 95,63% consideró que el primer paso en el tratamiento implica un control de la dieta, ejercicio físico, abandono del tabaco y si se precisa, tratamiento farmacológico. Un 19,1% estaba parcial o completamente de acuerdo en que el gemfibrozilo es el fibrato más adecuado para asociar con estatinas. El 74,83% estaba completamente de acuerdo en que el fenofibrato es el fibrato más apropiado para combinar con estatinas. Conclusiones: Los médicos tienen acceso a las guías y recomendaciones clínicas sobre el manejo de la DA, pero es necesario continuar concienciando de la importancia de su detección precoz y control óptimo para limitar su riesgo cardiovascular

The application of atherogenic dyslipidaemia consensus recommendations in the primary care setting. DAT-AP study / Grado de aplicación de los resultados del consenso de dislipemia aterogénica en el ámbito de Atención Primaria. Estudio DAT-AP

Background and aims: The ‘DAT-AP’ (from the Spanish, ‘Dislipemia ATerogénica en Atención Primaria’, for Atherogenic Dyslipidaemia in Primary Care) study objective is to determine to what extent published consensus guidelines for the diagnostic and therapeutic management of AD are used in the primary care setting, and to evaluate the approach of the participating physicians towards the detection, diagnosis, and treatment of AD. Methods: This is descriptive, cross-sectional, multicentre study performed between January and May 2015 in primary care centres throughout Spain. Study data were collected in 2 independent blocks, the first addressing theoretical aspects of AD and the second, practical aspects (clinical cases). Results: The theoretical part is in the process of publication. This manuscript depicts the clinical cases block. Although study participants showed good knowledge of the subject, the high prevalence of this disease requires an additional effort to optimise detection and treatment, with the implementation of appropriate lifestyle interventions and the prescription of the best treatment (AU)

Introducción y objetivos: El objetivo del estudio ‘DAT-AP’ (‘Dislipemia ATerogénica en Atención Primaria’) es determinar en qué medida las guías de consenso publicadas sobre el manejo diagnóstico y terapéutico de la dislipidemia aterogénica (DA) son utilizadas en el entorno de atención primaria, así como evaluar el abordaje de los médicos participantes en cuanto a la detección, diagnóstico y tratamiento de la DA. Métodos: Estudio transversal, descriptivo y multicéntrico, realizado entre Enero y Mayo de 2015 en centros de AP de España. Los datos fueron recogidos en 2 bloques independientes, en el que el primero recoge aspectos teóricos de la DA y el segundo aspectos prácticos (casos clínicos). Resultados: La parte teórica está en proceso de publicación. Este manuscrito describe el bloque relativo a los casos clínicos. Aunque los participantes del estudio mostraron un buen conocimiento de la materia, la alta prevalencia de esta enfermedad requiere un esfuerzo adicional para optimizar la detección y el tratamiento con la implementación de medidas adecuadas sobre el estilo de vida y la prescripción del mejor tratamiento (AU)

Severe neuropathy with leaky connexin32 hemichannels.

X-linked Charcot-Marie-Tooth disease is one of a set of diseases caused by mutations in gap junction proteins called connexins. We identified a connexin32 missense mutation (F235C) in a girl with unusually severe neuropathy. The localization and trafficking of the mutant protein in cell culture was normal, but electrophysiological studies showed that the mutation caused abnormal hemichannel opening, with excessive permeability of the plasma membrane and decreased cell survival. Abnormal leakiness of connexin hemichannels is likely a mechanism of cellular toxicity in this and perhaps other diseases caused by connexin mutations.

Molecular basis of calcium regulation in connexin-32 hemichannels.

In addition to forming gap-junction channels, a subset of connexins (Cxs) also form functional hemichannels. Most hemichannels are activated by depolarization, and opening depends critically on the external Ca2+ concentration. Here we describe the mechanisms of action and the structural determinants underlying the Ca2+ regulation of Cx32 hemichannels. At millimolar calcium concentrations, hemichannel voltage gating to the full open state of approximately 90 pS is inhibited, and ion conduction at negative voltages of the partially open hemichannels ( approximately 18 pS) is blocked. Thus, divalent cation blockage should be considered as a physiological mechanism to protect the cell from the potentially adverse effects of leaky hemichannels. A ring of 12 Asp residues within the external vestibule of the pore is responsible for the binding of Ca2+ that accounts for both pore occlusion and blockage of gating. The residue Asp-169 of one subunit and the Asp-178 of an adjacent subunit must be arranged precisely to allow interactions with Ca2+ to occur. Interestingly, a naturally occurring mutation (D178Y) that causes an inherited peripheral neuropathy induces a complete Ca2+ deregulation of Cx32 hemichannel activity, suggesting that this dysfunction may be involved in the pathogenesis of the neuropathy.