Molecular mechanisms and clonal lineages of colistin-resistant bacteria across the African continent: a scoping review.

Colistin (also known as polymyxin E), a polymyxin antibiotic discovered in the late 1940s, has recently reemerged as a last-line treatment option for multidrug-resistant infections. However, in recent years, colistin-resistant pathogenic bacteria have been increasingly reported worldwide. Accordingly, the presented review was undertaken to identify, integrate and synthesize current information regarding the detection and transmission of colistin-resistant bacteria across the African continent, in addition to elucidating their molecular mechanisms of resistance. PubMed, Google Scholar and Science Direct were employed for study identification, screening and extraction. Overall, based on the developed literature review protocol and associated inclusion/exclusion criteria, 80 studies published between 2000 and 2021 were included comprising varying bacterial species and hosts. Numerous mechanisms of colistin resistance were reported, including chromosomal mutation(s) and transferable plasmid-mediated colistin resistance (encoded by mcr genes). Perhaps unexpectedly, mcr-variants have exhibited rapid emergence and spread across most African regions. The genetic variant mcr-1 is predominant in humans, animals and the natural environment, and is primarily carried by IncHI2- type plasmid. The highest number of studies reporting the dissemination of colistin-resistant Gram-negative bacteria were conducted in the North African region.

Attenuation of 7-ketocholesterol- and 7ß-hydroxycholesterol-induced oxiapoptophagy by nutrients, synthetic molecules and oils: Potential for the prevention of age-related diseases.

Age-related diseases for which there are no effective treatments include cardiovascular diseases; neurodegenerative diseases such as Alzheimer's disease; eye disorders such as cataract and age-related macular degeneration; and, more recently, Severe Acute Respiratory Syndrome (SARS-CoV-2). These diseases are associated with plasma and/or tissue increases in cholesterol derivatives mainly formed by auto-oxidation: 7-ketocholesterol, also known as 7-oxo-cholesterol, and 7ß-hydroxycholesterol. The formation of these oxysterols can be considered as a consequence of mitochondrial and peroxisomal dysfunction, leading to increased in oxidative stress, which is accentuated with age. 7-ketocholesterol and 7ß-hydroxycholesterol cause a specific form of cytotoxic activity defined as oxiapoptophagy, including oxidative stress and induction of death by apoptosis associated with autophagic criteria. Oxiaptophagy is associated with organelle dysfunction and in particular with mitochondrial and peroxisomal alterations involved in the induction of cell death and in the rupture of redox balance. As the criteria characterizing 7-ketocholesterol- and 7ß-hydroxycholesterol-induced cytotoxicity are often simultaneously observed in major age-related diseases (cardiovascular diseases, age-related macular degeneration, Alzheimer's disease) the involvement of these oxysterols in the pathophysiology of the latter seems increasingly likely. It is therefore important to better understand the signalling pathways associated with the toxicity of 7-ketocholesterol and 7ß-hydroxycholesterol in order to identify pharmacological targets, nutrients and synthetic molecules attenuating or inhibiting the cytotoxic activities of these oxysterols. Numerous natural cytoprotective compounds have been identified: vitamins, fatty acids, polyphenols, terpenes, vegetal pigments, antioxidants, mixtures of compounds (oils, plant extracts) and bacterial enzymes. However, few synthetic molecules are able to prevent 7-ketocholesterol- and/or 7ß-hydroxycholesterol-induced cytotoxicity: dimethyl fumarate, monomethyl fumarate, the tyrosine kinase inhibitor AG126, memantine, simvastatine, Trolox, dimethylsufoxide, mangafodipir and mitochondrial permeability transition pore (MPTP) inhibitors. The effectiveness of these compounds, several of which are already in use in humans, makes it possible to consider using them for the treatment of certain age-related diseases associated with increased plasma and/or tissue levels of 7-ketocholesterol and/or 7ß-hydroxycholesterol.

Rabies in Tunisia: A spatio-temporal analysis in the region of CapBon-Nabeul.

Human rabies is a significant public health concern in Tunisia. However, the spatiotemporal spread pattern of rabies in dogs, the major reservoir and vector, and its determinants are poorly understood. We collected geographic locations and timeline of reported animal rabies cases in the region of CapBon (study area), for the years 2015-2019 and integrated them in Geographical Information System (GIS) approach to explore the spatio-temporal pattern of dog rabies. The results show that roads and irrigated areas can act as ecological corridors to viral spread. Our study showed that there was a significant seasonal variation in the number of cases of rabies recorded, with a strong peak in spring and lower peak in winter and summer. These findings may play a role in updating and directing public health policy, as well as providing opportunities for authorities to explore control options in time and space. A better knowledge of the ecology and dog population dynamics is still necessary and important to achieve an effective rabies control.

High occurrence of enterotoxigenic isolates and low antibiotic resistance rates of Staphylococcus aureus isolated from raw milk from cows and ewes.

This study aimed to analyse the frequency of genes encoding virulence factors and to characterize resistance profiles of Staphylococcus aureus isolated from raw milk. In total, 47 and 9 S. aureus isolates were recovered from 150 and 100 raw bovine and ovine milk samples, respectively, in Tunisia. The majority of isolates was resistant to penicillin, and no methicillin-resistant S. aureus was detected. Eighteen and two isolates harboured etd and eta genes respectively. Sixteen enterotoxin-encoding genes were detected (n, %): sed (25, 44·6%), sec (16, 28·6%), sei (16, 28·6%), seh (13, 23·2%), seln (13, 23·2%), sell (10, 17·8%), seg (9, 16%), selu (8, 14·3%), selq (7, 12·5%), selo (7, 12·5%), selm (7, 12·5%), seb (7, 12·5%), sea (6, 10·7%), selk (3, 5·4%), ser (1, 1·8%) and selp (1, 1·8%). Ten isolates carried the tsst1 gene. All isolates carried the haemolysin toxin (hla, hld and hlg). The immune evasion cluster system-type B was predominant (20 isolates) followed by C (3 isolates), A and E (1 isolate each). The occurrence of enterotoxigenic S. aureus in raw milk constitutes a potential risk for human health. SIGNIFICANCE AND IMPACT OF THE STUDY: This paper describes the characteristics of Staphylococcus aureus isolated from raw milk samples from healthy cows and ewes collected from small family farms in Tunisia. Fifty-six strains were analysed by determining their antibiotic susceptibility and genes encoding antibiotic resistance and virulence factors. Methicillin-resistant strains were not detected, and overall low level of antimicrobial resistance was reported. However, our strains harboured several genes encoding virulence factors and 87·5% of them carried at least one gene encoding for enterotoxins showing a high risk of spread of food-borne diseases.

[Resistance to vitamin K antagonist revealing interaction with soy lecithin]. / Résistance aux antivitamines K révélant une interaction avec la lécithine de soja.

Vitamin K antagonists (VKA) are difficult to use because of a narrow therapeutic index and of a marked inter- and intra-individual variability among patients in the required dosage. This drug may interact with many other drugs and same with certain food compounds. We report the case of potential interaction between soy lecithin and Vitamin K antagonists in a 46 years-old woman. Subtherapeutic INR values were detected despite the increase gradually in dose and replacing acenocoumarol by fluindione. An enquiry of pharmacovigilance was conducted found the consumption of soy lecithin capsules. Fifteen days after its stopping, the INR values have really increased. Clinicians should think to the possibility of interaction between oral anticoagulants and food supplement that is increasingly used.

Gender differences in the association of ELMO1 genetic variants with type 2 diabetes in Tunisian Arabs.

PURPOSE: Polymorphisms of the engulfment and cell motility 1 (ELMO1) gene were recently associated with type 2 diabetes (T2DM) and its complications. We investigated the association of rs10255208, rs7782979, and rs2041801 ELMO1 gene variants with T2DM in Tunisian Arabs. METHODS: Subjects comprised 900 T2DM patients and 600 normoglycemic controls. ELMO1 genotyping was done by PCR-RFLP; the contribution of ELMO1 variants to T2DM was analyzed by Haploview and regression analysis. RESULTS: Minor allele frequencies of rs7782979 and rs10255208 ELMO1 variants were significantly higher among unselected T2DM cases than controls, and significant differences in the distribution of rs7782979 genotypes were seen between T2DM cases and control subjects, which was seen in male but not female subjects. Three-locus ELMO1 haplotype analysis identified haplotype GAA to be positively associated, and haplotypes GCA, AAA, and GCG to be negatively associated with T2DM. The distribution of these haplotypes was gender-dependent for some (GCA, GCG, AAG), and gender-independent for others (GAA, AAA). This translated into altered risk of T2DM in male or female subjects, which persisted after adjusting for BMI, systolic and diastolic blood pressure, and serum lipid profile. CONCLUSION: These results confirm role for ELMO1 as T2DM susceptibility locus, which appears to be gender-dependent.

A novel Bluetongue virus serotype 3 strain in Tunisia, November 2016.

Since 1998, southern Europe has experienced multiple incursions of different serotypes and topotypes of Bluetongue virus, a vector-borne transmitted virus, the causative agent of Bluetongue (BT), a major disease of ruminants. Some of these incursions originated from northern Africa, likely because of wind-blown dissemination of infected midges. In this report, we describe the detection and whole genome characterization of a novel BTV-3 strain identified in a symptomatic sheep in Tunisia. Sequences were immediately deposited with the GenBank Database under Accession Nos KY432369-KY432378. Alert and preparedness are requested to face the next vector seasons in northern Africa and the potential incursion of this novel strain in southern Europe.

Identification of Suitable Areas for West Nile Virus Circulation in Tunisia.

West Nile virus (WNV) is a mosquito-transmitted Flavivirus belonging to the Japanese encephalitis antigenic complex of the Flaviviridae family. It is transmitted primarily by the bite of infected mosquitoes, particularly Culex spp. and Aedes/Ochlerotatus spp., which acquire the virus by feeding on viraemic birds. Humans, horses and other mammals are regarded as incidental or dead-end hosts. In the last decades, an increasing number of cases of WNV infection in horses and humans have been notified in the Mediterranean basin. In Tunisia, human cases of WNV-related meningoencephalitis were detected in 1997, 2003, 2007, 2010, 2011 and 2012. Based on the analysis of climatic and environmental conditions found in the locations where human cases have been reported in 2012, the aim of this study was to identify similar areas in Tunisia potentially at risk of disease occurrence. Data related to 85 neuroinvasive West Nile fever (WNF) human cases were georeferenced and a set of environmental and climatic variables (wetlands and humid areas, normalized difference vegetation index (NDVI), temperatures and elevation, migratory bird settlements) were used in the analysis. Areas, ecologically similar to those where human cases were detected, were identified using the Mahalanobis distance statistic. A leave-one-out cross-validation was performed to validate the sensitivity of the model, and 78 of 85 points were correctly classified.

Congenital neuroblastoma presenting with paraplegia following spinal puncture in a neonate. Case report and review of the literature.

Neuroblastoma is the most common intraspinal solid tumor of childhood. Neurological deterioration due to an intratumoral hemorrhage following a spinal puncture is extremely rare. We report on the case of a 23-day-old neonate who was admitted to our institution for the onset of a paraplegia following a diagnostic lumbar puncture. The MRI showed an epidural tumor with massive intratumoral hemorrhage. Operatively and with histologic confirmation, the mass was determined to be a neuroblastoma. Following surgery, neurological function improved.

HLA-G 14 bp insertion/deletion polymorphism and its association with sHLA-G levels in Behçet's disease Tunisian patients.

The purpose of this study was to investigate the HLA-G 3'UTR 14 bp polymorphism and sHLA-G levels in Tunisian patients with BD. The study included 119 patients with BD and 170 healthy blood donors (HD). HLA-G 14 bp polymorphism was genotyped by polymerase chain reaction. Serum levels of soluble HLA-G (sHLA-G) were measured using a commercial ELISA kit. A significant increased frequency of the -14 bp HLA-G allele was detected in patients with BD compared to HD (0.58 vs 0.49, p=0.023), and a significant increased frequency of HLA-G -14/-14 bp was observed in patients with BD compared to HD [0.37 vs 0.22, p=0.007, OR 2.04 (95% CI 1.21-3.42)]. The mean plasmatic concentration of sHLA-G levels were significantly increased in patients with active disease [231.63±286.4 U/mL] compared to those with inactive disease (103.14±77.8 U/mL, p=0.03) and HD (121.41±24.1 U/mL, p=0.04). Furthermore, our results showed that there is no association between HLA-G 14 bp polymorphism and sHLA-G plasma levels.

Identifying Areas Suitable for the Occurrence of Rift Valley Fever in North Africa: Implications for Surveillance.

Rift Valley fever (RVF) is a vector-borne zoonotic disease that has caused widespread outbreaks throughout Africa and the Arabian Peninsula, with serious consequences for livestock-based economies and public health. Although there have never been any reports of RVF in Morocco, Algeria, Tunisia and Libya, it is a priority disease in the Maghreb, due to the threat of introduction of the virus through transboundary livestock movements or infected mosquito vectors. However, the implementation of surveillance activities and early warning contingency plans requires better knowledge of the epidemiological situation. We conducted a multicriteria decision analysis, integrating host distribution with a combination of important ecological factors that drive mosquito abundance, to identify hotspots and suitable time periods for RVF enzootic circulation (i.e. stable transmission at a low to moderate level for an extended period of time) and an RVF epizootic event (i.e. a sudden occurrence of a large number of infected animals over a large geographic area) in the Maghreb. We also modelled vector species distribution using available information on vector presence and habitat preference. We found that the northern regions of the Maghreb were moderately suitable for RVF enzootics, but highly suitable for RVF epizootics. The vector species distribution model identified these regions as the most favourable mosquito habitats. Due to the low density of animal hosts and arid conditions, the desert region showed low RVF suitability, except in oases. However, the presence of competent vectors in putative unsuitable areas underlines the need for further assessments of mosquito habitat preference. This study produced monthly RVF suitability maps useful for animal health managers and veterinary services involved in designing risk-based surveillance programmes. The suitability maps can be further enhanced using existing country-specific sources of information and by incorporating knowledge - as it becomes available - on the epidemiology of the disease and distribution of vectors in the Maghreb.

Mucosal lichenoid drug reaction associated with glimepiride: a case report.

We report the case of a 52-year-old man with type 2 diabetes, who developed severe mucosal erosions of the tongue, glans penis and perianal area, induced by glimepiride. A tissue biopsy was performed and revealed the characteristics of lichen planus (LP). The improvement of the patient's condition after withdrawal of glimepiride added to recurrence of the lesions when medication was reintroduced confirmed that the second generation anti-diabetic was the causative agent. To the best of our knowledge, this has not been reported previously.

Relationship between GII.3 norovirus infections and blood group antigens in young children in Tunisia.

Noroviruses (NoVs) constitute a major cause of gastroenteritis in Tunisia. One hundred and fourteen matched saliva and stool samples were collected from children (n = 114) suffering from acute gastroenteritis at the hospital of Monastir during the winter season 2011-2012. For 98 of 114 children, blood samples were collected for secretor genotyping. NoVs were associated with 36.8% (n = 42/114) of the gastroenteritis cases. The GII.3 genotype was the most common (69% of all NoVs). For patients who were phenotyped (n = 114) for human blood group antigens (HBGAs), the secretor and non-secretor phenotypes represented 79% and 21%, respectively. Of the NoV infections, 83% were detected in all ABO groups. Five GII.3 isolates, one GII.1 isolate and one GII.7 isolate were detected in Lewis-positive non-secretors, confirmed by genotyping of the FUT2 gene. Even though our data showed that GII.3 NoVs could infect non-secretors, no binding was observed with saliva and GII.3 baculovirus-expressed virus-like particles from the same symptomatic non-secretor individual. This suggests that other factors might also participate in NoV attachment in children and newborns.

First detection of co-circulation of West Nile and Usutu viruses in equids in the south-west of Tunisia.

In the last fifteen years, West Nile Virus (WNV) has dramatically expanded its geographic range and is now considered the most widespread arbovirus in the world. In Tunisia, West Nile Fever (WNF) outbreaks were reported in humans in 1997, 2003 and 2012. Usutu Virus (USUV), which is a 'new' emerging Flavivirus antigenically close to WNV, has never been reported in Tunisia. A serological investigation in 284 equids was conducted in 2012 in the southern west region of the country to assess the presence and prevalence of the WNV and USUV infection. Of the 284 samples tested by competitive enzyme-linked immunoassay, 129 were positive. Of these, 120 (42.3%) had WNV-specific neutralizing antibodies. The prevalence was significantly higher in areas closer to the oasis compared with that of the surrounding arid areas. Antibody titres against USUV were also reported in 10 equids. This was the first evidence of USUV circulation in Tunisia. Data recorded by this study indicate that WNV and USUV have circulated/are circulating in the region and that there is an urgent need to adapt the current surveillance programmes to this new scenario.

Phenotypic abnormalities of peripheral blood mononuclear cells in patients with Behçet's disease and association with HLA-B51 expression.

The aim of this study was to investigate the subclasses and the immunophenotypic profile of peripheral mononuclear cells in patients with Behçet's disease (BD) and to assess associations between the expression of HLA-B51 antigen and that of other cell markers. Thirty healthy volunteer blood donors and forty patients with BD were enrolled into this study. Phenotyping was performed using two color flow cytometry. HLA-B51 typing was performed using the complement dependent microlymphocytotoxicity assay. Unlike controls, patients with BD presented a modified immunophenotypic profile of lymphocytes. Compared to those in the remission phase, patients with active BD showed an increased mean of MFI ratio of CD56 on CD16+CD56+ cells (32.47 ± 14.26 versus 23.87 ± 10.3; p = 0.032), increased absolute numbers of CD4(-)CD8(bright) and CD4(+)CD8(+) cells (657.1 ± 463.6 cells/µL versus 319.24 ± 116.4 cells/µL; p = 0.017 and 40.77 ± 36.41 cells/µL versus 10.77 ± 9.78 cells/µL; p < 0.0001, respectively) and an elevated mean of MFI ratio of CD19 on B cells (252.3 ± 56.7 versus 205.67 ± 32.3; p = 0.021). However, expression of HLA-B51 was not associated with any specific immunophenotypic profile. In conclusion, abnormal immunophenotypic profile of peripheral lymphocytes was found in patients with BD, especially in active phase, reflecting an immune dysregulation. Moreover, HLA-B51 expression was not found to be related to the expression of other cell markers.

In vitro developmental competence of prepubertal goat oocytes cultured with recombinant activin-A.

The present study was designed to evaluate the effect of activin-A during the in vitro oocyte maturation (IVM) and in vitro embryo culture (IVC) on nuclear maturation, blastocyst yield and blastocyst quality of prepubertal goat oocytes. In Experiment 1, three groups of oocytes were used during the IVM of prepubertal goat oocytes to determine the optimal concentration of recombinant human activin-A added to the maturation medium. Cumulus-oocyte complexes were matured in an IVM medium containing 0, 10 and 100 ng/ml (groups A0, A10 and A100), fertilized and in vitro cultured using standard procedures. In Experiment 2, the addition of 10 ng/ml activin-A at IVM (A10A0), IVC (A0A10) or IVM+IVC (A10A10) was studied and compared with the control group (A0A0). Results of the first experiment demonstrated that the addition of activin-A yielded similar percentages of maturation (⩽71.0%) and blastocyst formation rates (⩽24.9%) than the control group (A0). Experiment 2 showed that exposure of prepubertal goat oocytes to an IVC medium containing 10 ng/ml activin-A (A0A10) significantly increased the rates of development to the blastocyst stage, as compared with the control group (A0A0) (19.5±2.21% v. 13.1±2.37%, respectively; P<0.05). With regard to the blastocyst quality, total number of cells, inner cell mass (ICM) and trophectoderm of prepubertal goat embryos produced in the presence of activin-A did not differ significantly among experimental groups. In summary, these results indicate that supplementation of the IVC medium with activin-A enhances embryo development of prepubertal goat oocytes.

ANALYSIS OF BIOTIC AND ABIOTIC FACTORS INFLUENCING THE OCCURRENCE OF WEST NILE VIRUS INFECTION IN TUNISIA.

Eco-climatic conditions are often associated with the occurrence of West Nile Disease (WND) cases. Among the complex set of biotic and abiotic factors influencing the emergence and spread of this vector-borne disease, two main variables have been considered to have a great influence on the probability of West Nile Virus (WNV) introduction and circulation in Tunisia: the presence of susceptible bird populations and the existence of geographical areas where the environmental and climatic conditions are more favourable to mosquito multiplications. The aim of this study was to identify and classify the climatic and environmental variables possibly associated with the occurrence of WNVhuman cases in Tunisia. The following environmental and climatic variables have been considered: wetlands and humid areas, Normalised Difference Vegetation Index (NDVI), temperatures and elevation. A preliminary analysis for the characterization of main variables associated with areas with a history of WNV human cases in Tunisia between 1997 and 2011 has been made. This preliminary analysis clearly indicates the closeness to marshes ecosystem, where migratory bird populations are located, as an important risk factor for WNV infection. On the contrary the temperature absolute seems to be not a significant factor in Tunisian epidemiological situation. In relation to NDVI values, more complex considerations should be made.

Hypoxemic Bronchiolitis Related to Major Histocompatibility Class II Deficiency.

Major histocompatibility complex class II expression deficiency is an autosomal recessive primary combined immunodeficiency. The prevalence of this deficiency is the highest in Mediterranean areas, especially North Africa. Early diagnosis is essential due to high mortality in the first 2 years of life. Prognosis is very poor when bone marrow transplantation cannot be performed. We report the case of an infant with major histocompatibility complex class II expression deficiency revealed by hypoxemic bronchiolitis due to Pneumocystis jiroveci.

Developmental competence and embryo quality of small oocytes from pre-pubertal goats cultured in IVM medium supplemented with low level of hormones, insulin-transferrin-selenium and ascorbic acid.

The aim of this study was to test the effect of insulin-transferrin-selenium (ITS) and L-ascorbic acid (AA) supplementation and the hormonal level during in vitro maturation (IVM) of small oocytes from pre-pubertal goat on the blastocyst yield and quality. Concretely, we used four maturation media: conventional IVM medium (CM), growth medium (GM: CM+ITS+AA and low level of hormones), modified CM (mCM: CM with low level of hormones) and modified GM (mGM: CM+ITS+AA and normal level of hormones). Cumulus-oocyte complexes (COCs) were classified into two categories according to oocyte diameter: <125 µm and ≥ 125 µm. Large oocytes were matured 24 h in CM (Treatment A). Small oocytes were matured randomly in six experimental groups: Treatment B: 24 h in CM; Treatment C: 12 h in GM and 12 h in CM; Treatment D: 24 h in mGM; Treatment E: 12 h in mGM and 12 h in CM; Treatment F: 12 h in mCM and 12 h in CM; and Treatment G: 12 h in GM and 12 h in mGM. After IVM, oocytes were fertilized and cultured for 8 days. The blastocyst quality was assessed by the survival following vitrification/warming and the mean cell number. When different maturation media were combined, the blastocyst rate did not improve. The large oocytes produced the highest blastocysts yield. However, the culture of small oocytes in GM (53.3%) enhanced the post-warming survival of blastocysts compared to large oocytes matured in CM (35.7%). In conclusion, IVM of pre-pubertal goat small oocytes in GM would be useful to improve the quality of in vitro-produced blastocysts.

Purinergic signalling - a possible mechanism for KCNQ1 channel response to cell volume challenges.

AIM: A number of K(+) channels are regulated by small, fast changes in cell volume. The mechanisms underlying cell volume sensitivity are not known, but one possible mechanism could be purinergic signalling. Volume activated ATP release could trigger signalling pathways that subsequently lead to ion channel stimulation and cell volume back-regulation. Our aim was to investigate whether volume sensitivity of the voltage-gated K(+) channel, KCNQ1, is dependent on ATP release and regulation by purinergic signalling. METHODS: We used Xenopus oocytes heterologously expressing human KCNQ1, KCNE1, water channels (AQP1) and P2Y2 receptors. ATP release was monitored by a luciferin-luciferase assay and ion channel conductance was recorded by two-electrode voltage clamp. RESULTS: The luminescence assay showed that oocytes released ATP in response to mechanical, hypoosmotic stimuli and hyperosmotic stimuli. Basal ATP release was approx. three times higher in the KCNQ1 + AQP1 and KCNQ1 injected oocytes compared to the non-injected ones. Exogenously added ATP (0.1 mm) did not have any substantial effect on volume-induced KCNQ1 currents. Nevertheless, apyrase decreased all currents by about 50%. Suramin inhibited about 23% of the KCNQ1 volume sensitivity. Expression of P2Y2 receptors stimulated endogenous Cl(-) channels, but it also led to 68% inhibition of the KCNQ1 currents. Adenosine (0.1 mm) also inhibited the KCNQ1 currents by about 56%. CONCLUSION: Xenopus oocytes release ATP in response to mechanical stimuli and cell volume changes. Purinergic P2 and P1 receptors confer some of the KCNQ1 channel volume sensitivity, although endogenous adenosine receptors and expressed P2Y2 receptors do so in the negative direction.