Inhibition of human recombinant T-type calcium channels by phytocannabinoids in vitro

BACKGROUND AND PURPOSE

T-type Ca channels (I_Ca ) regulate neuronal excitability and contribute to neurotransmitter release. The phytocannabinoids Δ⁹ -tetrahydrocannabinol and cannabidiol effectively modulate T-type I_Ca , but effects of other biologically active phytocannabinoids on these channels are unknown. We thus investigated the modulation of T-type I_Ca by low abundance phytocannabinoids.

EXPERIMENTAL APPROACH

A fluorometric (FLIPR) assay was used to investigate modulation of human T-type I_Ca (Ca_V 3.1, 3.2 and 3.3) stably expressed in FlpIn-TREx HEK293 cells. The biophysical effects of some compounds were examined using whole-cell patch clamp recordings from the same cells.

KEY RESULTS

In the FLIPR assay, all eleven phytocannabinoids tested modulated T-type I_Ca , with most inhibiting Ca_V 3.1 and Ca_V 3.2 more effectively than Ca_V 3.3. Cannabigerolic acid was the most potent inhibitor of Ca_V 3.1 (pIC₅₀ 6.1 ± 0.6) and Ca_V 3.2 (pIC₅₀ 6.4 ± 0.4); in all cases phytocannabinoid acids were more potent than their corresponding neutral forms. In patch clamp recordings, cannabigerolic acid inhibited Ca_V 3.1 and 3.2 with similar potency to the FLIPR assay, the inhibition was associated with significant hyperpolarizing shift in activation and steady state inactivation of these channels. In contrast, cannabidiol, cannabidivarin and cannabigerol only affected channel inactivation.

CONCLUSION AND IMPLICATIONS

Modulation of T-type calcium channels is a common property of phytocannabinoids, which all increase steady state inactivation at physiological membrane potentials, with some also affecting channel activation. Thus, T-type I_Ca may be a common site of action for phytocannabinoids, and the diverse actions of phytocannabinoids on channel gating may provide insight into structural requirement for selective T-type I_Ca modulators.

Synthesis and pharmacological evaluation of newly detected synthetic cannabinoid receptor agonists AB-4CN-BUTICA, MMB-4CN-BUTINACA, MDMB-4F-BUTICA, MDMB-4F-BUTINACA and their analogs

Synthetic cannabinoid receptor agonists (SCRAs) continue to make up a significant portion new psychoactive substances (NPS) detected and seized worldwide. Due to their often potent activation of central cannabinoid receptors in vivo, use of SCRAs can result in severe intoxication, in addition to other adverse health effects. Recent detections of AB-4CN-BUTICA, MMB-4CN-BUTINACA, MDMB-4F-BUTICA and MDMB-4F-BUTINACA mark a continuation in the appearance of SCRAs bearing novel tail substituents. The proactive characterization campaign described here has facilitated the detection of several new SCRAs in toxicological case work. Here we detail the synthesis, characterization, and pharmacological evaluation of recently detected SCRAs, as well as a systematic library of 32 compounds bearing head, tail, and core group combinations likely to appear in future. In vitro radioligand binding assays revealed most compounds showed moderate to high affinity at both CB₁ (pK _i = < 5 to 8.89 ± 0.09 M) and CB₂ (pK _i = 5.49 ± 0.03 to 9.92 ± 0.09 M) receptors. In vitro functional evaluation using a fluorescence-based membrane potential assay showed that most compounds were sub-micromolar to sub-nanomolar agonists at CB₁ (pEC₅₀ = < 5 to 9.48 ± 0.14 M) and CB₂ (pEC₅₀ = 5.92 ± 0.16 to 8.64 ± 0.15 M) receptors. An in silico receptor-ligand docking approach was utilized to rationalize binding trends for CB₂ with respect to the tail substituent, and indicated that rigidity in this region (i.e., 4-cyanobutyl) was detrimental to affinity.

Gene-specific MicroRNA antagonism protects against HIV Tat and TGF-β-mediated suppression of CFTR mRNA and function

BACKGROUND

MicroRNAs play an important role in health and disease. TGF-β signaling, upregulated by HIV Tat, and in chronic airway diseases and smokers upregulates miR-145-5p to suppress cystic fibrosis transmembrane conductance regulator (CFTR). CFTR suppression in chronic airway diseases like Cystic Fibrosis, COPD and smokers has been associated with suppressed MCC and recurrent lung infections and inflammation. This can explain the emergence of recurrent lung infections and inflammation in people living with HIV.

METHODS

Tat-induced aberrant microRNAome was identified by miRNA expression analysis. microRNA mimics and antagomirs were used to validate the identified miRNAs involved in Tat mediated CFTR mRNA suppression. CRISPR-based editing of the miRNA target sites in CFTR 3'UTR was used to determine rescue of CFTR mRNA and function in airway epithelial cell lines and in primary human bronchial epithelial cells exposed to TGF-β and Tat.

FINDINGS

HIV Tat upregulates miR-145-5p and miR-509-3p. The two miRNAs demonstrate co-operative effects in suppressing CFTR. CRISPR-based editing of the miRNA target site preserves CFTR mRNA and function in airway epithelial cells INTERPRETATION: Given the important roles of TGF-β signaling and the multitude of genes regulated by miRNAs, we demonstrate that CRISPR-based gene-specific microRNA antagonism approach can preserve CFTR mRNA and function in the context of HIV Tat and TGF-β signaling without suppressing expression of other genes regulated by miR-145-5p.

Changes in hemodynamics, renal blood flow and urine output during continuous renal replacement therapies

Continuous renal replacement therapies (CRRT) affect hemodynamics and urine output. Some theories suggest a reduced renal blood flow as the cause of the decreased urine output, but the exact mechanisms remain unclear. A prospective experimental study was carried out in 32 piglets (2–3 months old) in order to compare the impact of CRRT on hemodynamics, renal perfusion, urine output and renal function in healthy animals and in those with non-oliguric acute kidney injury (AKI). CRRT was started according to our clinical protocol, with an initial blood flow of 20 ml/min, with 10 ml/min increases every minute until a goal flow of 5 ml/kg/min. Heart rate, blood pressure, central venous pressure, cardiac output, renal blood flow and urine output were registered at baseline and during the first 6 h of CRRT. Blood and urine samples were drawn at baseline and after 2 and 6 h of therapy. Blood pressure, cardiac index and urine output significantly decreased after starting CRRT in all piglets. Renal blood flow, however, steadily increased throughout the study. Cisplatin piglets had lower cardiac index, higher vascular resistance, lower renal blood flow and lower urine output than control piglets. Plasma levels of ADH and urine levels of aquaporin-2 were lower, whereas kidney injury biomarkers were higher in the cisplatin group of piglets. According to our findings, a reduced renal blood flow doesn’t seem to be the cause of the decrease in urine output after starting CRRT.

Hematological complications in children subjected to extracorporeal membrane oxygenation

OBJECTIVES

To analyze the hematological complications and need for transfusions in children receiving extracorporeal life support (ECLS).

DESIGN

A retrospective study was carried out.

SETTING

A pediatric intensive care unit.

PATIENTS

Children under 18 years of age subjected to ECLS between September 2006 and November 2015.

INTERVENTIONS

None.

VARIABLES OF INTEREST

Patient and ECLS characteristics, anticoagulation, hematological and coagulation parameters, transfusions and clinical course.

RESULTS

A total of 100 patients (94 with heart disease) with a median age of 11 months were studied. Seventy-six patients presented bleeding. The most frequent bleeding point was the mediastinum and 39 patients required revision surgery. In the first 3days, 97% of the patients required blood transfusion (34.4ml/kg per day), 94% platelets (21.1ml/kg per day) and 90% plasma (26.6ml/kg per day). Patients who were in the postoperative period, those who were bleeding at the start of ECLS, those requiring revision surgery, those who could not suspend extracorporeal circulation, and those subjected to transthoracic cannulation required a greater volume of transfusions than the rest of the patients. Thromboembolism occurred in 14 patients and hemolysis in 33 patients. Mortality among the children who were bleeding at the start of ECLS (57.6%) was significantly higher than in the rest of the patients (37.5%) (P=.048).

CONCLUSIONS

Children subjected to ECLS present high blood product needs. The main factors related to transfusions were the postoperative period, bleeding at the start of ECLS, revision surgery, transthoracic cannulation, and the impossibility of suspending extracorporeal circulation. Children with bleeding suffered greater mortality than the rest of the patients.

[Long-term outcomes of children treated with continuous renal replacement therapy]

INTRODUCTION

The objective of this study is to analyze long-term outcomes and kidney function in children requiring continuous renal replacement therapy (CRRT) after an acute kidney injury episode.

PATIENTS AND METHODS

A retrospective observational study was performed using a prospective database of 128 patients who required CRRT admitted to the pediatric intensive care unit between years 2006 and 2012. The subsequent outcomes were assessed in those surviving at hospital discharge.

RESULTS

Of the 128 children who required RRT in the pediatric intensive care unit, 71 survived at hospital discharge (54.4%), of whom 66 (92.9%) were followed up. Three patients had chronic renal failure prior to admission to the NICU. Of the 63 remaining patients, 6 had prolonged or relapses of renal function disturbances, but only one patient with atypical Hemolytic Uremic Syndrome developed end-stage renal failure. The rest had normal kidney function at the last check-up.

CONCLUSIONS

Most of surviving children that required CRRT have a positive outcome later on, presenting low mortality rates and recovery of kidney function in the medium term.

Does the opinion of the therapeutic team match with psychometric measures during the course of eating disorders?

INTRODUCTION

Is there a group of psychometric variables, which correlates with the criteria of an interdisciplinary team about the course of ED?

OBJECTIVES

The aim of this study was to analyse the correlation between the clinic criteria of an interdisciplinary team with respect to the course of eating disorders (ED) and different psychometric criteria.

METHODS

The course was analysed in a final sample of 30 ED outpatients during their six first months of treatment. A scale of clinical criteria of the course of ED (therapeutic team's opinion) and different questionnaires on psychological, psychopathological and eating-related variables were used. The statistical analysis comprised of a discriminant analysis in order to find the variables with a discriminant function to distinguish between a fair-bad course and a good course.

RESULTS

Perceived stress, self-esteem, the variables of the SCL-90-R, depression, thought-shape fusion, anxiety, food craving and the score on body shape questionnaire were found to have discriminant function. Comparing the therapeutic team's criteria and the results of the questionnaires a 10% of patients were misclassified.

DISCUSSION

The results highlight the necessary and permanent checking of the relationship among the clinical criteria regarding the course of ED (members' team opinion) and different psychological, psychopathological and eating-related variables.

[Thrombolytic therapy using a low dose of tissue plasminogen activator in children]

OBJECTIVE

To analyse the efficacy and side effects of low doses of tissue plasminogen activator for the treatment of acute arterial and/or venous thrombosis in children.

PATIENTS AND METHODS

Prospective observational clinical study. 18 children between 1 months and 11 years treated with low doses (0.01-0.06 mg/kg/h) of continuous intravenous thrombolytic therapy with t-PA were studied.

RESULTS

A total of 94% of patients improved with low doses t-PA (72% complete resolution of the thrombosis and 22% partial resolution). One patient suffered a severe haemorrhage secondary to t-Pa and had to stop the treatment. The incidence of severe side effects was low (5%)

CONCLUSIONS

Thrombolytic therapy with low doses of t-PA (0.01-0.05 mg/kg/h) is effective in a high percentage of children with acute arterial and/or venous thrombosis and produces a relatively low frequency of side effects.

Risk factors for gastrointestinal complications in critically ill children with transpyloric enteral nutrition

OBJECTIVE

To study the risk factors for gastrointestinal complications related to enteral nutrition in critically ill children.

DESIGN

A prospective, observational study.

SETTING

Pediatric intensive care unit.

SUBJECTS

Five hundred and twenty-six critically ill children who received transpyloric enteral nutrition(TEN).

METHODS

Univariate and multivariate logistic regression analysis were used to identify risk factors for gastrointestinal complications.

RESULTS

Sixty six patients (11.5%) presented gastrointestinal complications, 33 (6.2%) abdominal distension and/or excessive gastric residue, 34 (6.4%) diarrhea, one gastrointestinal bleeding, three necrotizing enterocolitis and one duodenal perforation. Enteral nutrition was definitively suspended because of gastrointestinal complications in 11 (2.1%) patients. Fifty patients (9.5%) died. Gastrointestinal complications were more frequent in the patients who died. Death was related to complications of the nutrition in only one patient. The frequency of gastrointestinal complications was significantly higher in children with shock, acute renal failure, hypokalemia, hypophosphatemia and in those receiving dopamine, epinephrine and vecuronium. The stepwise multivariate logistic regression analysis showed that the most important factors associated with gastrointestinal complications were shock, epinephrine at a rate higher than 0.3 microg/kg/min and hypophosphatemia.

CONCLUSIONS

The tolerance of TEN in critically ill children is good, although the incidence of gastrointestinal complications is higher in patients with shock, acute renal failure, hypokalemia, hypophosphatemia, and those receiving epinephrine, dopamine, and vecuronium.

Percutaneous placement of inferior vena cava filters

Pulmonary embolism is a serious and difficult problem. Many approaches for the prevention of recurrent pulmonary embolism have been tried. Percutaneous placement of inferior vena cava filters is an easy, safe, available and well established procedure for the prevention of pulmonary embolism. The authors review the indications for use of IVC filters, and they review the main filters available in terms of ease of use, the physical characteristics, the technique of introduction, the efficacy and morbidity, and the potential complications associated with their use. Insertion of IVC filters by percutaneous approach was successfully performed in 6 patients with recurrent pulmonary embolism. Following the intervention procedure without complication there were no further pulmonary emboli.