How Student and Faculty Perceptions Differ on the Stressors that Medical Students Face.

OBJECTIVES: Medical education is notorious for the stress that students face as they strive to succeed both academically and clinically. This stress has been linked to declining academic performance and worsening mental health. To combat these negative outcomes, it is essential for medical school faculty and administration to address common stressors among medical students. No studies have addressed whether medical school faculty and students perceive stressors similarly, however. METHODS: In this two-part study, data collected from medical students in 2021 to 2022 to identify their most significant sources of stress were used to create a survey that queries the frequency and intensity of these stressors. This survey was distributed to medical students and faculty at the same institution. The responses between students and faculty were compared and student data also were analyzed by academic year to observe changes in perception that accompany progression through the medical curriculum. RESULTS: The results showed that faculty overestimated the impact of certain stressors on medical students (eg, in-house examinations, US Medical Licensing Examination Steps 1 and 2 examinations, and patient interactions). In addition, preclinical students were more concerned with finding extracurricular activities, missing opportunities, and performing research compared with clinical students. CONCLUSIONS: This study demonstrated that although faculty anticipated most medical student stressors, there are significant gaps that still need to be addressed to better reduce and respond to the stress experienced by medical students.

Kidney Stone Pathophysiology, Evaluation and Management: Core Curriculum 2023.

Kidney stone disease, also known as nephrolithiasis or urolithiasis, is a disorder in which urinary solutes precipitate to form aggregates of crystalline material in the urinary space. The incidence of nephrolithiasis has been increasing, and the demographics have been evolving. Once viewed as a limited disease with intermittent exacerbations that are simply managed by urologists, nephrolithiasis is now recognized as a complex condition requiring thorough evaluation and multifaceted care. Kidney stones are frequently manifestations of underlying systemic medical conditions such as the metabolic syndrome, genetic disorders, or endocrinopathies. Analysis of urine chemistries and stone composition provide a window into pathogenesis and direct ancillary studies to uncover underlying diseases. These studies allow providers to devise individualized strategies to limit future stone events. Given its complexity, kidney stone disease is best addressed by a team led by nephrologists and urologists with input from multiple other health professionals including dietitians, endocrinologists, interventional radiologists, and endocrine surgeons. In this installment of AJKD's Core Curriculum in Nephrology, we provide a case-based overview of nephrolithiasis, divided by the individual stone types. The reader will gain a pragmatic understanding of the pathophysiology, evaluation, and management of this condition.

Using dipstick urinalysis to predict development of acute kidney injury in patients with COVID-19.

BACKGROUND: Acute kidney injury (AKI) is a common complication in patients hospitalized with COVID-19 and may require renal replacement therapy (RRT). Dipstick urinalysis is frequently obtained, but data regarding the prognostic value of hematuria and proteinuria for kidney outcomes is scarce. METHODS: Patients with positive severe acute respiratory syndrome-coronavirus 2 (SARS-CoV2) PCR, who had a urinalysis obtained on admission to one of 20 hospitals, were included. Nested models with degree of hematuria and proteinuria were used to predict AKI and RRT during admission. Presence of Chronic Kidney Disease (CKD) and baseline serum creatinine were added to test improvement in model fit. RESULTS: Of 5,980 individuals, 829 (13.9%) developed an AKI during admission, and 149 (18.0%) of those with AKI received RRT. Proteinuria and hematuria degrees significantly increased with AKI severity (P < 0.001 for both). Any degree of proteinuria and hematuria was associated with an increased risk of AKI and RRT. In predictive models for AKI, presence of CKD improved the area under the curve (AUC) (95% confidence interval) to 0.73 (0.71, 0.75), P < 0.001, and adding baseline creatinine improved the AUC to 0.85 (0.83, 0.86), P < 0.001, when compared to the base model AUC using only proteinuria and hematuria, AUC = 0.64 (0.62, 0.67). In RRT models, CKD status improved the AUC to 0.78 (0.75, 0.82), P < 0.001, and baseline creatinine improved the AUC to 0.84 (0.80, 0.88), P < 0.001, compared to the base model, AUC = 0.72 (0.68, 0.76). There was no significant improvement in model discrimination when both CKD and baseline serum creatinine were included. CONCLUSIONS: Proteinuria and hematuria values on dipstick urinalysis can be utilized to predict AKI and RRT in hospitalized patients with COVID-19. We derived formulas using these two readily available values to help prognosticate kidney outcomes in these patients. Furthermore, the incorporation of CKD or baseline creatinine increases the accuracy of these formulas.

Hyperphosphatemia and its relationship with blood pressure, vasoconstriction, and endothelial cell dysfunction in hypertensive hemodialysis patients.

BACKGROUND: Hyperphosphatemia occurs frequently in end-stage renal disease patients on hemodialysis and is associated with increased mortality. Hyperphosphatemia contributes to vascular calcification in these patients, but there is emerging evidence that it is also associated with endothelial cell dysfunction. METHODS: We conducted a cross-sectional study in hypertensive hemodialysis patients. We obtained pre-hemodialysis measurements of total peripheral resistance index (TPRI, non-invasive cardiac output monitor) and plasma levels of endothelin-1 (ET-1) and asymmetric dimethylarginine (ADMA). We ascertained the routine peridialytic blood pressure (BP) measurements from that treatment and the most recent pre-hemodialysis serum phosphate levels. We used generalized linear regression analyses to determine independent associations between serum phosphate with BP, TPRI, ET-1, and ADMA while controlling for demographic variables, parathyroid hormone (PTH), and interdialytic weight gain. RESULTS: There were 54 patients analyzed. Mean pre-HD supine and seated systolic and diastolic BP were 164 (27), 158 (21), 91.5 (17), and 86.1 (16) mmHg. Mean serum phosphate was 5.89 (1.8) mg/dL. There were significant correlations between phosphate with all pre-hemodialysis BP measurements (r = 0.3, p = .04; r = 0.4, p = .002; r = 0.5, p < .0001; and r = 0.5, p = .0003.) The correlations with phosphate and TPRI, ET-1, and ADMA were 0.3 (p = .01), 0.4 (p = .007), and 0.3 (p = .04). In our final linear regression analyses controlling for baseline characteristics, PTH, and interdialytic weight gain, independent associations between phosphate with pre-hemodialysis diastolic BP, TPRI, and ET-1 were retained (ß = 4.33, p = .0002; log transformed ß = 0.05, p = .005; reciprocal transformed ß = -0.03, p = .047). CONCLUSIONS: Serum phosphate concentration is independently associated with higher pre-HD BP, vasoconstriction, and markers of endothelial cell dysfunction. These findings demonstrate an additional negative impact of hyperphosphatemia on cardiovascular health beyond vascular calcification. TRIAL REGISTRATION: The study was part of a registered clinical trial, NCT01862497 (May 24, 2013).

APOL1 genotype-associated morphologic changes among patients with focal segmental glomerulosclerosis.

BACKGROUND: The G1 and G2 alleles of apolipoprotein L1 (APOL1) are common in the Black population and associated with increased risk of focal segmental glomerulosclerosis (FSGS). The molecular mechanisms linking APOL1 risk variants with FSGS are not clearly understood, and APOL1's natural absence in laboratory animals makes studying its pathobiology challenging. METHODS: In a cohort of 90 Black patients with either FSGS or minimal change disease (MCD) enrolled in the Nephrotic Syndrome Study Network (58% pediatric onset), we used kidney biopsy traits as an intermediate outcome to help illuminate tissue-based consequences of APOL1 risk variants and expression. We tested associations between APOL1 risk alleles or glomerular APOL1 mRNA expression and 83 light- or electron-microscopy traits measuring structural and cellular kidney changes. RESULTS: Under both recessive and dominant models in the FSGS patient subgroup (61%), APOL1 risk variants were significantly correlated (defined as FDR <0.1) with decreased global mesangial hypercellularity, decreased condensation of cytoskeleton, and increased tubular microcysts. No significant correlations were detected in MCD cohort. Independent of risk alleles, glomerular APOL1 expression in FSGS patients was not correlated with morphologic features. CONCLUSIONS: While APOL1-associated FSGS is associated with two risk alleles, both one and two risk alleles are associated with cellular/tissue changes in this study of FSGS patients. Our lack of discovery of a large group of tissue differences in FSGS and no significant difference in MCD may be due to the lack of power but also supports investigating whether machine learning methods may more sensitively detect APOL1-associated changes.

Microbiological Evaluation of the Extension Wire and Percutaneous Epidural Lead Anchor Site Following a "2-Stage Cut-Down" Spinal Cord Stimulator Procedure.

OBJECTIVES: There are concerns regarding bacterial colonization of the temporary extension leads and subsequent infection risk using the 2-stage cut-down approach in spinal cord stimulation (SCS). We sought to quantify the extent of bacterial colonization of the temporary extension wire and percutaneous epidural lead anchor site. MATERIALS AND METHODS: We conducted a cross-sectional observational study recruiting a pragmatic sample of 25 consecutive patients listed for a cut-down trial of SCS. We excluded patients undergoing revision procedures and those who had previously received a spinal cord stimulator. The primary outcome measure was the rate and type of colonization of the extension wires and lead anchor site. RESULTS: No surgical site infections were recorded in any of the patients and no late infections subsequent to insertion of the implantable pulse generator. Overall, 24% of patients grew organisms from the temporary extension wire. Five patients grew coagulase-negative Staphylococcus aureus, and 1 patient grew Enterococcus faecalis. There were no positive wound cultures from the anchor site of the epidural lead. CONCLUSIONS: Despite the high colonization rate of the temporary extension wire, there were no surgical site infections. We conclude that provided appropriate strategies for the management of surgical site infections are implemented, the 2-stage cut-down procedure is a safe approach that is not associated with a higher incidence of infection.

Hemodialysis catheter insertion: is increased PO2 a sign of arterial cannulation? A case report.

BACKGROUND: Ultrasound-guided Central Venous Catheterization (CVC) for temporary vascular access, preferably using the right internal jugular vein, is widely accepted by nephrologists. However CVC is associated with numerous potential complications, including death. We describe the finding of a rare left-sided partial anomalous pulmonary vein connection during central venous catheterization for continuous renal replacement therapy (CRRT). CASE PRESENTATION: Ultrasound-guided cannulation of a large bore temporary dual-lumen Quinton-Mahurkar catheter into the left internal jugular vein was performed for CRRT initiation in a 66 year old African-American with sepsis-related oliguric acute kidney injury. The post-procedure chest X-ray suggested inadvertent left carotid artery cannulation. Blood gases obtained from the catheter showed high partial pressure of oxygen (PO2) of 140 mmHg and low partial pressure of carbon dioxide (PCO2) of 22 mmHg, suggestive of arterial cannulation. However, the pressure-transduced wave forms appeared venous and Computed Tomography Angiography located the catheter in the left internal jugular vein, but demonstrated that the tip of the catheter was lying over a left pulmonary vein which was abnormally draining into the left brachiocephalic (innominate) vein rather than into the left atrium. CONCLUSION: Although several mechanical complications of dialysis catheters have been described, ours is one of the few cases of malposition into an anomalous pulmonary vein, and highlights a sequential approach to properly identify the catheter location in this uncommon clinical scenario.

Off-target depletion of plasma tryptophan by allosteric inhibitors of BCKDK.

The activation of branched chain amino acid (BCAA) catabolism has garnered interest as a potential therapeutic approach to improve insulin sensitivity, enhance recovery from heart failure, and blunt tumor growth. Evidence for this interest relies in part on BT2, a small molecule that promotes BCAA oxidation and is protective in mouse models of these pathologies. BT2 and other analogs allosterically inhibit branched chain ketoacid dehydrogenase kinase (BCKDK) to promote BCAA oxidation, which is presumed to underlie the salutary effects of BT2. Potential "off-target" effects of BT2 have not been considered, however. We therefore tested for metabolic off-target effects of BT2 in Bckdk-/- animals. As expected, BT2 failed to activate BCAA oxidation in these animals. Surprisingly, however, BT2 strongly reduced plasma tryptophan levels and promoted catabolism of tryptophan to kynurenine in both control and Bckdk-/- mice. Mechanistic studies revealed that none of the principal tryptophan catabolic or kynurenine-producing/consuming enzymes (TDO, IDO1, IDO2, or KATs) were required for BT2-mediated lowering of plasma tryptophan. Instead, using equilibrium dialysis assays and mice lacking albumin, we show that BT2 avidly binds plasma albumin and displaces tryptophan, releasing it for catabolism. These data confirm that BT2 activates BCAA oxidation via inhibition of BCKDK but also reveal a robust off-target effect on tryptophan metabolism via displacement from serum albumin. The data highlight a potential confounding effect for pharmaceutical compounds that compete for binding with albumin-bound tryptophan.

Sodium-glucose co-transporter 2 Inhibitors Act Independently of SGLT2 to Confer Benefit for Heart Failure with Reduced Ejection Fraction in Mice.

Sodium-glucose co-transporter 2 inhibitors (SGLT2i) are novel, potent heart failure medications with an unknown mechanism of action. We sought to determine if the beneficial actions of SGLT2i in heart failure were on- or off-target, and related to metabolic reprogramming, including increased lipolysis and ketogenesis. The phenotype of mice treated with empagliflozin and genetically engineered mice constitutively lacking SGLT2 mirrored metabolic changes seen in human clinical trials (including reduced blood glucose, increased ketogenesis, and profound glucosuria). In a mouse heart failure model, SGLT2i treatment, but not generalized SGLT2 knockout, resulted in improved systolic function and reduced pathologic cardiac remodeling. SGLT2i treatment of the SGLT2 knockout mice sustained the cardiac benefits, demonstrating an off-target role for these drugs. This benefit is independent of metabolic changes, including ketosis. The mechanism of action and target of SGLT2i in HF remain elusive.

Two-hit mouse model of heart failure with preserved ejection fraction combining diet-induced obesity and renin-mediated hypertension.

Heart failure with preserved ejection fraction (HFpEF) is increasingly common but its pathogenesis is poorly understood. The ability to assess genetic and pharmacologic interventions is hampered by the lack of robust preclinical mouse models of HFpEF. We have developed a novel "2-hit" model, which combines obesity and insulin resistance with chronic pressure overload to recapitulate clinical features of HFpEF. C57BL6/NJ mice fed a high fat diet for >10 weeks were administered an AAV8-driven vector resulting in constitutive overexpression of mouse Renin1d . Control mice, HFD only, Renin only and HFD-Renin (aka "HFpEF") littermates underwent a battery of cardiac and extracardiac phenotyping. HFD-Renin mice demonstrated obesity and insulin resistance, a 2-3-fold increase in circulating renin levels that resulted in 30-40% increase in left ventricular hypertrophy, preserved systolic function, and diastolic dysfunction indicated by altered E/e', IVRT, and strain measurements; increased left atrial mass; elevated natriuretic peptides; and exercise intolerance. Transcriptomic and metabolomic profiling of HFD-Renin myocardium demonstrated upregulation of pro-fibrotic pathways and downregulation of metabolic pathways, in particular branched chain amino acid catabolism, similar to findings in human HFpEF. Treatment of these mice with the sodium-glucose cotransporter 2 inhibitor empagliflozin, an effective but incompletely understood HFpEF therapy, improved exercise tolerance, left heart enlargement, and insulin homeostasis. The HFD-Renin mouse model recapitulates key features of human HFpEF and will enable studies dissecting the contribution of individual pathogenic drivers to this complex syndrome. Addition of HFD-Renin mice to the preclinical HFpEF model platform allows for orthogonal studies to increase validity in assessment of interventions. NEW & NOTEWORTHY: Heart failure with preserved ejection fraction (HFpEF) is a complex disease to study due to limited preclinical models. We rigorously characterize a new two-hit HFpEF mouse model, which allows for dissecting individual contributions and synergy of major pathogenic drivers, hypertension and diet-induced obesity. The results are consistent and reproducible in two independent laboratories. This high-fidelity pre-clinical model increases the available, orthogonal models needed to improve our understanding of the causes and assessment treatments for HFpEF.

Glycolytic lactate in diabetic kidney disease.

Lactate elevation is a well-characterized biomarker of mitochondrial dysfunction, but its role in diabetic kidney disease (DKD) is not well defined. Urine lactate was measured in patients with type 2 diabetes (T2D) in 3 cohorts (HUNT3, SMART2D, CRIC). Urine and plasma lactate were measured during euglycemic and hyperglycemic clamps in participants with type 1 diabetes (T1D). Patients in the HUNT3 cohort with DKD had elevated urine lactate levels compared with age- and sex-matched controls. In patients in the SMART2D and CRIC cohorts, the third tertile of urine lactate/creatinine was associated with more rapid estimated glomerular filtration rate decline, relative to first tertile. Patients with T1D demonstrated a strong association between glucose and lactate in both plasma and urine. Glucose-stimulated lactate likely derives in part from proximal tubular cells, since lactate production was attenuated with sodium-glucose cotransporter-2 (SGLT2) inhibition in kidney sections and in SGLT2-deficient mice. Several glycolytic genes were elevated in human diabetic proximal tubules. Lactate levels above 2.5 mM potently inhibited mitochondrial oxidative phosphorylation in human proximal tubule (HK2) cells. We conclude that increased lactate production under diabetic conditions can contribute to mitochondrial dysfunction and become a feed-forward component to DKD pathogenesis.

Catheterization Without Supination-A Series of 36 Prone Position Internal Jugular Vein Cannulations.

Describe the clinical characteristics and outcomes of 32 critically ill patients who underwent central venous cannulation of the internal jugular vein while in prone position. DESIGN: Retrospective cohort analysis. SETTING: Single tertiary-care urban academic safety-net hospital. PATIENTS/SUBJECTS: Patients requiring mechanical ventilation and prone positioning for severe acute respiratory distress syndrome from March 1, 2020, through March 31, 2021. INTERVENTIONS: Internal jugular vein cannulation while in the prone position. MEASUREMENTS AND MAIN RESULTS: The technique used for venous access, procedural complications, patient demographics, and clinical outcomes are described. Thirty-six prone internal jugular vein cannulations for 32 hemodialysis catheters and four central venous catheters were successfully performed in 32 patients. One immediate and one delayed pneumothorax occurred. Inhospital mortality was 88%. CONCLUSIONS: In the largest series to date, cannulation of the internal jugular vein with the patient in prone position is feasible but associated with a 6% risk of pneumothorax. Severity of illness in patients intolerant of supine positioning results in high inhospital mortality.

Safety and Feasibility of Photodynamic Therapy for Ablation of Peripheral Lung Tumors.

BACKGROUND: Newer navigational bronchoscopy technologies render peripheral lung lesions accessible for biopsy and potential treatment. We investigated whether photodynamic therapy (PDT) delivered via navigational bronchoscopy is feasible and safe for ablation of peripheral lung tumors. METHODS: Two studies evaluated PDT in patients with solid peripheral lung tumors followed by clinical follow-up (nonresection study, N=5) or lobectomy (resection study, N=10). Porfimer sodium injection was administered 40 to 50 hours before navigational bronchoscopy. Lesion location was confirmed by radial probe endobronchial ultrasonography. An optical fiber diffuser was placed within or adjacent to the tumor under fluoroscopic guidance; laser light (630 nm wavelength) was applied at 200 J/cm of diffuser length for 500 seconds. Tumor response was assessed by modified Response Evaluation Criteria in Solid Tumors at 3 and 6 months postprocedure (nonresection study) and pathologically (resection study). RESULTS: There were no deaths, discontinuations for adverse events, or serious or grade ≥3 adverse events related to study treatments. Photosensitivity reactions occurred in 8 of 15 patients: 6 mild, 1 moderate, 1 severe (elevated porphyrins noted in blood after treatment). Among 5 patients with clinical follow-up, 1 had complete response, 3 had stable disease, and 1 had progressive disease at 6 months follow-up. Among 10 patients who underwent lobectomy, 1 had no evidence of tumor at resection (complete response), 3 had 40% to 50% tumor cell necrosis, 2 had 20% to 35%, and 4 had 5% to 10%. CONCLUSION: PDT for nonthermal ablation of peripheral lung tumors was feasible and safe in this small study. Further study is warranted to evaluate efficacy and corroborate the safety profile.

Synthetic polymer nanoparticle-polysaccharide interactions: a systematic study.

The interaction between synthetic polymer nanoparticles (NPs) and biomacromolecules (e.g., proteins, lipids, and polysaccharides) can profoundly influence the NPs fate and function. Polysaccharides (e.g., heparin/heparin sulfate) are a key component of cell surfaces and the extracelluar matrix and play critical roles in many biological processes. We report a systematic investigation of the interaction between synthetic polymer nanoparticles and polysaccharides by ITC, SPR, and an anticoagulant assay to provide guidelines to engineer nanoparticles for biomedical applications. The interaction between acrylamide nanoparticles (~30 nm) and heparin is mainly enthalpy driven with submicromolar affinity. Hydrogen bonding, ionic interactions, and dehydration of polar groups are identified to be key contributions to the affinity. It has been found that high charge density and cross-linking of the NP can contribute to high affinity. The affinity and binding capacity of heparin can be significantly diminished by an increase in salt concentration while only slightly decreased with an increase of temperature. A striking difference in binding thermodynamics has been observed when the main component of a polymer nanoparticle is changed from acrylamide (enthalpy driven) to N-isopropylacryalmide (entropy driven). This change in thermodynamics leads to different responses of these two types of polymer NPs to salt concentration and temperature. Select synthetic polymer nanoparticles have also been shown to inhibit protein-heparin interactions and thus offer the potential for therapeutic applications.

Preparation and characterization of nanocapsules for colon-targeted drug delivery system.

CONTEXT: Nanoparticles for colon-specific drug delivery system are known for their specific accumulation in the inflamed tissue in the colon and may therefore allow a selective delivery to the site of inflammation for the treatment of inflammatory bowel disease (IBD). OBJECTIVE: The objective of this study was to formulate and evaluate nanocapsules (NC), an oral system designed to achieve site-specific and instant drug release in colon for effective treatment of IBD. MATERIALS AND METHODS: Prednisolone (PD), a typical glucocorticoid, has been widely used for the treatment of IBD. In this study, nanoprecipitation method was used to prepare polymeric NC of PD with pH responsive polymer Eudragit S100. The effect of several formulation variables such as surfactant, oil, and polymer on the PD-NC properties (average size, drug release rate, and drug entrapment) was investigated. In vitro drug release study was done by changing pH method and an in vivo study on rat was done to ascertain efficiency of PD-NC to release drug specifically in colon. RESULTS AND DISCUSSION: The optimized formulations lead to the preparation of PD-NC with a mean size of 567.87 nm, high encapsulation efficiency of 90.21%. In vitro studies reveal that NC releases the drug after 4.5-h lag time corresponding to time to reach colonic region, and in vivo studies show that NC release drug after 3-h lag time in rat corresponds to arrival in colon. CONCLUSION: The above NC formulation of PD is the targeted drug to the colon and may provide effective way of treatment of colonic disease.

Molecular Signatures of Diabetic Kidney Disease Hiding in a Patient with Hypertension-Related Kidney Disease: A Clinical Pathologic Molecular Correlation.

The Kidney Precision Medicine Project (KPMP) seeks to establish a molecular atlas of the kidney in health and disease and improve our understanding of the molecular drivers of CKD and AKI. Herein, we describe the case of a 66-year-old woman with CKD who underwent a protocol KPMP kidney biopsy. Her clinical history included well-controlled diabetes mellitus, hypertension, and proteinuria. The patient's histopathology was consistent with modest hypertension-related kidney injury, without overt diabetic kidney disease. Transcriptomic signatures of the glomerulus, interstitium, and tubular subsegments were obtained from laser microdissected tissue. The molecular signatures that were uncovered revealed evidence of early diabetic kidney disease adaptation and ongoing active tubular injury with enriched pathways related to mesangial cell hypertrophy, glycosaminoglycan biosynthesis, and apoptosis. Molecular evidence of diabetic kidney disease was found across the nephron. Novel molecular assays can supplement and enrich the histopathologic diagnosis obtained from a kidney biopsy.

Dicoumarol complexes of Cu(II) based on 1,10-phenanthroline: synthesis, X-ray diffraction studies, thermal behavior and biological evaluation.

A series of Cu(II) complexes containing dicoumarol derivatives and 1, 10-phenanthroline have been synthesized. Structural and spectroscopic properties of ligands were studied on the basis of mass spectra, NMR ((1)H and (13)C) spectra, FT-IR spectrophotometry and elemental analysis, while physico-chemical, spectroscopic and thermal properties of mixed ligand complexes have been studied on the basis of infrared spectra, mass spectra, electronic spectra, powder X-ray diffraction, elemental analysis and thermogravimetric analysis. X-ray diffraction study suggested the suitable octahedral geometry for hexa-coordinated state. The kinetic parameters such as order of reaction (n), energy of activation (Ea), entropy (S(*)), pre-exponential factor (A), enthalpy (H(*)) and Gibbs free energy (G(*)) have been calculated using Freeman-Carroll method. Ferric-reducing antioxidant power (FRAP) of all complexes were measured. All the compounds were screened for their antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Streptococcus pyogenes and Bacillus subtilis, while antifungal activity against Candida albicans and Aspergillus niger have been carried out. Also compounds against Mycobacterium tuberculosis shows clear enhancement in the anti-tubercular activity upon copper complexation.

Multiple heating rate kinetic parameters, thermal, X-ray diffraction studies of newly synthesized octahedral copper complexes based on bromo-coumarins along with their antioxidant, anti-tubercular and antimicrobial activity evaluation.

Series of new Cu(II) complexes were synthesized by classical thermal technique. The biologically potent ligands (L) were prepared by refluxing 6-brom 3-acetyl coumarin with aldehydes in the presence of piperidine in ethanol. The Cu(II) complexes have been synthesized by mixing an aqueous solution of Cu(NO(3))(2) in 1:1 molar ratios with ethanolic bidentate ligands and Clioquinol. The structures of the ligands and their copper complexes were investigated and confirmed by the elemental analysis, FT-IR, (1)H NMR, (13)C NMR, mass spectral and powder X-ray diffraction studies respectively. Thermal behaviour of newly synthesized mixed ligand Cu(II) complexes were investigated by means of thermogravimetry, differential thermogravimetry, differential scanning calorimetry, electronic spectra and magnetic measurements. Dynamic scan of DSC experiments for Cu(II) complexes were taken at different heating rates (2.5-20 °C min(-1)). Kinetic parameters for second step degradation of all complexes obtained by Kissinger's and Ozawa's methods were in good agreement. On the basis of these studies it is clear that ligands coordinated to metal atom in a monobasic bidentate mode, by OO and ON donor system. Thus, suitable octahedral geometry for hexa-coordinated state has been suggested for the metal complexes. Both the ligands as well as its complexes have been screened for their in vitro antioxidant, anti-tubercular and antimicrobial activities. All were found to be significant potent compared to parent ligands employed for complexation.