Anthropogenic sources and liquid water drive secondary organic aerosol formation over the eastern Himalaya.

Atmospheric aerosols have a serious impact on altering the radiation balance of the vulnerable Himalayan atmosphere. Organic aerosol (OA), one of the least resolved aerosol fractions in the Himalayas, constrain our competence to assess their climate impacts on the region. Here we investigate water-soluble OA molecules in PM10 samples collected from March to May 2019 at Lachung (27.4°N and 88.4°E), a high-altitude location (2700 m a.s.l.) in the eastern Himalaya, to elucidate their origin and formation process. The dominance of oxalic acid (C2) reveals that water-soluble OA in the eastern Himalaya are atmospherically processed. Backward air mass trajectories and mass concentration ratios of organic tracers as well as relationships with inorganic species (K+, SO42-, NH4+) suggest an anthropogenic origin of water-soluble OA with significant atmospheric processing during long-range transport to the eastern Himalayan region. We used the thermodynamic prediction of aerosol liquid water (ALW) to examine the formation mechanism of secondary OA (SOA) such as oxalic acid. Correlations of ALW with SO42- and water-soluble organic matter show that ALW is sensitive to both anthropogenic sulfate and water-soluble organic compounds in Himalayan aerosols. A strong positive relationship of C2 acid with predicted ALW provides evidence of extensive SOA formation from precursors via aqueous phase photochemical processes. This inference is supported by positive correlations of C2 acid relative abundance with diagnostic mass concentration ratios of C2 acid to precursor molecules. Our findings underscore the importance of anthropogenic sources and ALW in SOA formation through aqueous phase processes in the eastern Himalaya.

Molecular composition and light-absorbing properties of organic aerosols from west-coast of tropical India.

Tropical coastal regions may provide a unique feature to study the photooxidation of various organic aerosols and their climatic effects because of high humid atmosphere and intense solar radiation. However, knowledge about organic molecular composition and its light absorption properties remains concealed, particularly over tropical Indian regions. The present study is an investigation on water-soluble dicarboxylic acids, ω-oxoacids, pyruvic acid, α-dicarbonyls, brown carbon (BrC), and other chemical species in PM1.1 collected at a coastal urban location (Kochi) on the west coast of tropical India under distinct air masses. Molecular distribution of dicarboxylic acids was characterized by the predominance of oxalic acid (C2) in all the air masses followed by adipic (C6) or terephthalic (tPh) and phthalic (Ph) acids. On average, total diacids-C accounted for 5.03 ± 1.01 % of TC. Total diacid concentration showed strong linear relationships with organic (OC), elemental carbon (EC), and non-sea-salt potassium (nss-K+). Except for the northwest (NW) air mass period, the concentration of C2 diacid and its ratios (C2/total diacids, C2/ωC2, C2/Gly) showed a strong linear relationship with nss-SO42-. By combining all these results together with Pearson correlation analysis, the present study demonstrates that organic aerosols over the study region were predominantly produced by aqueous-phase oxidation of precursor compounds derived from biomass burning and combustion-related emissions. The mass absorption coefficient of BrC (babs-BrC-365nm) was strongly correlated with nss-K+, implying that biomass burning emissions are major sources of BrC. The absorption angstrom exponent (AÅE) values of water (methanol) extracts ranged from 3.20 to 3.83 (3.05-4.55) during the entire sampling period, indicating the substantial contribution of BrC chromophores to light absorption over the region. On average, BrC absorbs 10.6 ± 6.4 % and 22.4 ± 5.75 % of solar radiation compared to BC in water and methanol extracts, respectively, suggesting that BrC is a significant aerosol climate forcing agent over the west coast of tropical India.

Significance of 'recovery ST-segment depression' in exercise stress test.

OBJECTIVE: To study the significance of ST-segment depression during 'recovery' compared to that 'during stress' and 'both the phases' in exercise stress test. METHODS: Patients with positive exercise stress test who underwent coronary angiography (CAG) from 1st January 2017 to 31st December 2018 were studied. Patients were divided into 3 groups- Group A with ST-depression restricted to recovery phase, group B with ST-depression restricted to stress phase and group C with ST-depression seen both during exercise and recovery. All patients underwent CAG. Sensitivity, specificity, and predictive values of each of these groups in diagnosis of significant coronary artery disease (CAD) were analysed and compared. RESULTS: Total 300 patients were studied. Mean age of the study population was 48.77 ± 7.94 years. 78.3% of patients with positive exercise stress test had significant CAD. 96% of patients in group A had significant CAD, which was higher than in group B (88.9%) & group C (70.1%). The specificity, positive predictive value and negative predictive value of ST-segment depression in group A (96.92%, 96% and 25.2% respectively) were higher than that of ST-depression in group B (89.23%, 88.89% and 24.47% respectively) and group C (13.85%, 70.05% and 7.96% respectively). Sensitivity and accuracy of ST-depression in group A were lower (20.43% and 37% respectively), compared to other 2 groups. CONCLUSION: Patient with ST-depression restricted to recovery phase had highest specificity, positive predictive value, and negative predictive value. However, accuracy was highest in group with both stress phase and exercise ST-segment depression.

A Prospective Study of Pulmonary Hypertension in Patients with Chronic Kidney Disease: A New and Pernicious Complication.

Pulmonary hypertension (PH) is a recently recognized complication of chronic kidney disease (CKD), especially in end-stage renal disease. It has prevalence estimates of 30%-50% and is an independent predictor of increased mortality in CKD patients. The aim of this study is to analyze the prevalence of PH in patients with CKD, its severity in different stages of CKD, and risk factors for it. One hundred and eight patients with CKD treated at Karnataka Institute of Medical Sciences, Hubli, Karnataka, between January 1, 2014, and June 30, 2015, were selected. Clinical evaluation and relevant investigations including echocardiography were done. Follow-up echocardiography was done at 3 and 6 months and assessed. The mean age of studied population was 43.53 ± 14.63 years. Sex ratio was 2.72:1 (male:female). PH was present in 47 of 108 (43.5%) cases at beginning, 41 of 83 (491.4%) at 3 months, and 32 of 64 (50%) at 6 months. The prevalence and severity of PH increased with progression of CKD stage, although not statistically significant. Heart failure with reduced ejection fraction and heart failure with preserved EF were significantly higher among PH group compared to non-PH group (P < 0.01). Mean hemoglobin in PH group was significantly lower, compared to non-PH group (P < 0.01). Mean interdialytic weight gain and central venous pressure were higher among PH group than non-PH group. Higher calcium phosphate product ≥50 was more prevalent in PH group than in non-PH group. The majority of them had moderate PH at the beginning of the study which remained same, despite being on hemodialysis. PH is a common complication in CKD patients with prevalence of 43.5%-50%. Left-sided heart failure, anemia, fluid retention, and increased calcium phosphate product are the risk factors for developing PH.

A Study of Correlation of Neck Circumference with Framingham Risk Score as a Predictor of Coronary Artery Disease.

INTRODUCTION: It has been observed that metabolic syndrome is risk factor for Coronary Artery Disease (CAD) and exerts its effects through fat deposition and vascular aging. CAD has been acknowledged as a leading cause of death. In earlier studies, the metabolic risk has been estimated by Framingham risk score. Recent studies have shown that Neck Circumference (NC) has a good correlation with other traditional anthropometric measurements and can be used as marker of obesity. It also correlates with Framingham risk score, which is slightly more sophisticated measure of CAD risk. AIM: To assess the risk of CAD in a subject based on NC and to correlate the NC to Framingham risk score. MATERIALS AND METHODS: The present cross-sectional study, done at Karnataka Institute of Medical Sciences, Hubli, Karnataka, India, includes 100 subjects. The study duration was of one year from 1st January 2015 to 31st December 2015. Anthropometric indices Body Mass Index (BMI) and NC were correlated with 10 year CAD risk as calculated by Framingham risk score. The correlation between BMI, NC, vascular age and Framingham risk score was calculated using Karl Pearson's correlation method. RESULTS: NC has a strong correlation with 10 year CAD risk (p≤0.001). NC was significantly greater in males as compared to females (p≤0.001). Males had greater risk of cardiovascular disease as reflected by higher 10 year Framingham risk score (p≤0.0035). CONCLUSION: NC gives simple and easy prediction of CAD risk and is more reliable than traditional risk markers like BMI. NC correlates positively with 10 year Framingham risk score.

Neck Circumference and Leg Length as Surrogate Markers of Coronary Artery Disease - Simplifying Cardiac Risk Stratification.

INTRODUCTION: Coronary angiography is the gold standard for quantification of coronary atherosclerosis. But, being invasive, it has inherent complications. Hence, we examined the accuracy of prediction of coronary angiography using simple anthropometric indices. AIM: To identify a patient friendly method to predict coronary artery disease using simple anthropometric parameters, by testing their correlation with coronary artery disease severity scoring system. MATERIALS AND METHODS: We conducted a cross-sectional study on patients undergoing elective coronary angiography. A total of 48 patients were included in the study. Neck circumference and leg length of the patients were noted. The severity of coronary atherosclerosis was quantified using Jenkin's scoring system. Mean and standard deviation for each continuous variable was calculated. The correlation between Jenkins' score, neck circumference and leg length was tested. The data analysis was done using IBM-SPSS software. RESULTS: Mean leg length among the study population was 88.70 cm (±2.51 cm) among males, 79.04 cm (±4.32 cm) among females and 83.66 cm (±3.26 cm) overall. Mean neck circumference was 36.87 cm (±4.37 cm) among males, 36.04 cm (±3.65 cm) among females and 36.44 cm (±3.99 cm) when combined together. There was no correlation of Jenkin's scores with leg length. But, there was significant correlation between Jenkin's scores and neck circumference. CONCLUSION: Neck circumference can be used as a simple and effective tool and is better than leg length for risk stratification of patients with coronary heart disease.