Statins are potent inhibitors of HMG-CoA reductase, the key rate-limiting enzyme in cholesterol biosynthesis, and are some of the best selling drugs globally. We have explored the effect of chronic cholesterol depletion induced by mevastatin on the function of human serotonin(1A) receptors expressed in CHO cells. An advantage with statins is that cholesterol depletion is chronic which mimics physiological conditions. Our results show a significant reduction in the level of specific ligand binding and G-protein coupling to serotonin(1A) receptors upon chronic cholesterol depletion, although the membrane receptor level is not reduced at all. Interestingly, replenishment of mevastatin-treated cells with cholesterol resulted in the recovery of specific ligand binding and G-protein coupling. Treatment of cells expressing serotonin(1A) receptors with mevastatin led to a decrease in the diffusion coefficient and an increase in the mobile fraction of the receptor, as determined by fluorescence recovery after photobleaching measurements. To the best of our knowledge, these results constitute the first report describing the effect of chronic cholesterol depletion on the organization and function of a G-protein-coupled neuronal receptor. Our results assume significance in view of recent reports highlighting the symptoms of anxiety and depression in humans upon statin administration, and the role of serotonin(1A) receptors in anxiety and depression.
Cholesterol crystalline domains characterize atherosclerotic membranes, altering vascular signaling and function. Omega-3 fatty acids reduce membrane lipid peroxidation and subsequent cholesterol domain formation. We evaluated non-peroxidation-mediated effects of eicosapentaenoic acid (EPA), other TG-lowering agents, docosahexaenoic acid (DHA), and other long-chain fatty acids on membrane fluidity, bilayer width, and cholesterol domain formation in model membranes. In membranes prepared at 1.5:1 cholesterol-to-phospholipid (C/P) mole ratio (creating pre-existing domains), EPA, glycyrrhizin, arachidonic acid, and alpha linolenic acid promoted the greatest reductions in cholesterol domains (by 65.5%, 54.9%, 46.8%, and 45.2%, respectively) compared to controls; other treatments had modest effects. EPA effects on cholesterol domain formation were dose-dependent. In membranes with 1:1 C/P (predisposing domain formation), DHA, but not EPA, dose-dependently increased membrane fluidity. DHA also induced cholesterol domain formation without affecting temperature-induced changes in-bilayer unit cell periodicity relative to controls (d-space; 57Å-55Å over 15-30°C). Together, these data suggest simultaneous formation of distinct cholesterol-rich ordered domains and cholesterol-poor disordered domains in the presence of DHA. By contrast, EPA had no effect on cholesterol domain formation and produced larger d-space values relative to controls (60Å-57Å; p<0.05) over the same temperature range, suggesting a more uniform maintenance of lipid dynamics despite the presence of cholesterol. These data indicate that EPA and DHA had different effects on membrane bilayer width, membrane fluidity, and cholesterol crystalline domain formation; suggesting omega-3 fatty acids with differing chain length or unsaturation may differentially influence membrane lipid dynamics and structural organization as a result of distinct phospholipid/sterol interactions.
The infection with SARS-CoV-2 is reported to be accompanied by the shedding of the virus in faecal samples of infected patients. Earlier reports have suggested that COVID-19 agents can be present in the sewage samples and thus it can be a good indication of the pandemic extent in a community. However, no such studies have been reported in the Indian context. Hence, it becomes absolutely necessary to detect the presence of the SARS-CoV-2 in the wastewater samples from wastewater treatment plants (WWTPs) serving different localities of Jaipur city. Samples from different WWTPs and hospital wastewater samples were collected and wastewater based epidemiology (WBE) studies were carried out using the RT-PCR to confirm the presence of different COVID-19 target genes namely S gene, E gene, ORF1ab gene, RdRp gene and N gene. The results revealed that the untreated wastewater samples showed the presence of SARS-CoV-2 viral genome, which was correlated with the increased number of COVID-19 positive patients from the concerned areas, as reported in the publically available health data. This is the first study that investigated the presence of SARS-CoV-2 viral genome in wastewater, at higher ambient temperature (45 °C), further validating WBE as potential tool in predicting and mitigating outbreaks.
Lipids that are labeled with the NBD (7-nitrobenz-2-oxa-1,3-diazol-4-yl) group are widely used as fluorescent analogues of native lipids in biological and model membranes to monitor a variety of processes. The NBD group of acyl chain labeled NBD lipids is known to loop up to the membrane interface in fluid phase membranes. However, the organization of these lipids in gel phase membranes is not resolved. In this paper, we monitored the influence of the membrane phase state on the looping up behavior of acyl chain labeled NBD lipids utilizing red edge excitation shift (REES) and other sensitive fluorescence approaches. Interestingly, our REES results indicate that NBD group of lipids, which are labeled at the fatty acyl region, resides in the more hydrophobic region in gel phase membranes, and complete looping of the NBD group occurs only in the fluid phase. This is supported by other fluorescence parameters such as polarization and lifetime. Taken together, our results demonstrate that membrane packing, which depends on temperature and the phase state of the membrane, significantly affects the localization of acyl chain labeled NBD lipids. In view of the wide ranging use of NBD-labeled lipids in cell and membrane biology, these results could have potentially important implications in future studies involving these lipids as tracers.
Astrocytes and microglia are activated during cerebral malaria (CM) and contribute to the production and release of several mediators during neuroinflammatory processes. Whether these changes are the consequence of a direct crosstalk between glial cells and the malarial parasite and how these cells participate in the pathogenesis of CM is not yet clear. We therefore examined the interaction of astrocytes and microglia with Plasmodium berghei ANKA-infected red blood cells using primary cell cultures derived from newborn C57BL/6 mice. We observed a dynamic transfer of vesicles from the parasite to astrocytes within minutes of contact, and the phagocytosis of infected red blood cells by microglia. Differential gene expression studies using the Affymetrix GeneChip microarray, and quantitative PCR analyses showed the increase in expression of the set of genes belonging to the immune response network in parasite activated astrocytes and microglia. Interestingly, expression of these genes was also significantly upregulated in brains of mice dying from CM compared with uninfected mice or infected mice that did not develop the neuropathology. Accumulation of parasite-derived vesicles within astrocytes, and the phagocytosis of infected red blood cells by microglia induced a subsequent increase in interferon gamma inducible protein 10 (IP10) in both the brain and plasma of infected mice at the onset of CM, confirming a role for this molecule in CM pathogenesis. Altogether, these observations point to a possible role for glial cells in the neuropathological processes leading to CM. GLIA 2016 GLIA 2017;65:75-92.
Background The Lancet Commission on Global Surgery established the Three Delays framework, categorising delays in accessing timely surgical care into delays in seeking care (First Delay), reaching care (Second Delay), and receiving care (Third Delay). Globally, knowledge gaps regarding delays for fracture care, and the lack of large prospective studies informed the rationale for our international observational study. We investigated delays in hospital admission as a surrogate for accessing timely fracture care and explored factors associated with delayed hospital admission. MethodsIn this prospective observational substudy of the ongoing International Orthopaedic Multicenter Study in Fracture Care (INORMUS), we enrolled patients with fracture across 49 hospitals in 18 low-income and middle-income countries, categorised into the regions of China, Africa, India, south and east Asia, and Latin America. Eligible patients were aged 18 years or older and had been admitted to a hospital within 3 months of sustaining an orthopaedic trauma. We collected demographic injury data and time to hospital admission. Our primary outcome was the number of patients with open and closed fractures who were delayed in their admission to a treating hospital. Delays for patients with open fractures were defined as being more than 2 h from the time of injury (in accordance with the Lancet Commission on Global Surgery) and for those with closed fractures as being a delay of more than 24 h. Secondary outcomes were reasons for delay for all patients with either open or closed fractures who were delayed for more than 24 h. We did logistic regression analyses to identify risk factors of delays of more than 2 h in patients with open fractures and delays of more than 24 h in patients with closed fractures. Logistic regressions were adjusted for region, age, employment, urban living, health insurance, interfacility referral, method of transportation, number of fractures, mechanism of injury, and fracture location. We further calculated adjusted relative risk (RR) from adjusted odds ratios, adjusted for the same variables. This study was registered with ClinicalTrials.gov, NCT02150980, and is ongoing. Findings Between April 3, 2014, and May 10, 2019, we enrolled 31 255 patients with fractures, with a median age of 45 years (IQR 31-62), of whom 19 937 (63•8%) were men, and 14 524 (46•5%) had lower limb fractures, making them the most common fractures. Of 5256 patients with open fractures, 3778 (71•9%) were not admitted to hospital within 2 h. Of 25 999 patients with closed fractures, 7141 (27•5%) were delayed by more than 24 h. Of all regions, Latin America had the greatest proportions of patients with delays (173 [88•7%] of 195 patients with open fractures; 426 [44•7%] of 952 with closed fractures). Among patients delayed by more than 24 h, the most common reason for delays were interfacility referrals (3755 [47•7%] of 7875) and Third Delays (cumulatively interfacility referral and delay in emergency department: 3974 [50•5%]), while Second Delays ...
The infection with SARS-CoV-2 is reported to be accompanied by the shedding of the virus in stool samples of infected patients. Earlier reports have suggested that COVID-19 agents can be present in the fecal and sewage samples and thus it can be a good indication of the pandemic extent in a community. However, no such studies have been reported in the Indian context so far. Since, several factors like local population physiology, the climatic conditions, sewage composition, and processing of samples could possibly affect the detection of the viral genome, it becomes absolutely necessary to check for the presence of the SARS-CoV-2 in the wastewater samples from wastewater treatment plants (WWTPs) serving different localities of Jaipur city, which has been under red zone (pandemic hotspots) since early April 2020. Samples from different local municipal WWTPs and hospital wastewater samples were collected and wastewater based epidemiology (WBE) studies for the presence of SARS-CoV-2 were carried out using the RT-PCR technique to confirm the presence of different COVID-19 target genes namely S gene, E gene, ORF1ab gene, RdRp gene and N gene in the viral load of wastewater samples. In the present study, the untreated wastewater samples from the municipal WWTPs and hospital wastewater samples showed the presence of SARS-CoV-2 viral genome, which was correlated with the increased number of COVID-19 positive patients from the concerned areas, as per reported in the publically available health data. This is the first study that investigated the presence of SARS-CoV-2 viral genome in wastewater, at higher ambient temperature (above 40°C), further validating WBE as a potential tool in predicting and mitigating outbreaks.
The organization and dynamics of cellular membranes in the nervous system are crucial for the function of neuronal membrane receptors and signal transduction. Previous work from our laboratory has established hippocampal membranes as a convenient natural source for studying neuronal receptors. In this paper, we have monitored the organization and dynamics of hippocampal membranes and their modulation by cholesterol using pyrene fluorescence. The apparent dielectric constant experienced by pyrene in hippocampal membranes turns out to be ∼20 ( 3, depending on the experimental condition. Our results show that the polarity of the hippocampal membrane is increased upon cholesterol depletion, as monitored by changes in the ratio of pyrene vibronic peak intensities (I 1 /I 3 ). This is accompanied by an increase in lateral diffusion, measured as an increase in the pyrene excimer/monomer ratio. These results are relevant in understanding the complex organization and dynamics of hippocampal membranes and could have implications in neuronal diseases characterized by defective cholesterol metabolism.
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