Actionability of Recommendations for Additional Imaging in Head and Neck Radiology.

PURPOSE: The aims of this study were to measure the actionability of recommendations for additional imaging (RAIs) in head and neck CT and MRI, for which there is a near complete absence of best practices or guidelines; to identify the most common recommendations; and to assess radiologist factors associated with actionability. METHODS: All head and neck CT and MRI radiology reports across a multi-institution, multipractice health care system from June 1, 2021, to May 31, 2022, were retrospectively reviewed. The actionability of RAIs was scored using a validated taxonomy. The most common RAIs were identified. Actionability association with radiologist factors (gender, years out of training, fellowship training, practice type) and with trainees was measured using a mixed-effects model. RESULTS: Two hundred nine radiologists generated 60,543 reports, of which 7.2% (n = 4,382) contained RAIs. Only 3.9% of RAIs (170 of 4,382) were actionable. More than 60% of RAIs were for eight examinations: thyroid ultrasound (14.1%), neck CT (12.6%), brain MRI (6.9%), chest CT (6.5%), neck CT angiography (5.5%), temporal bone CT (5.3%), temporal bone MRI (5.2%), and pituitary MRI (4.6%). Radiologists >23 years out of training (odds ratio, 0.39; 95% confidence interval, 0.15-1.02; P = .05) and community radiologists (odds ratio, 0.53; 95% confidence interval, 0.22-1.31; P = .17) had substantially lower estimated odds of making actionable RAIs than radiologists <7 years out of training and academic radiologists, respectively. CONCLUSIONS: The studied radiologists rarely made actionable RAIs, which makes it difficult to identify and track clinically necessary RAIs to timely performance. Multifaceted quality improvement initiatives including peer comparisons, clinical decision support at the time of reporting, and the development of evidence-based best practices, may help improve tracking and timely performance of clinically necessary RAIs.

Recommendations for Additional Imaging on Head and Neck Imaging Examinations: Interradiologist Variation and Associated Factors.

Background: A paucity of relevant guidelines may lead to pronounced variation among radiologists in issuing recommendations for additional imaging (RAI) for head and neck imaging. Objective: To explore associations of RAI for head and neck imaging examinations with examination, patient, and radiologist factors, and to assess the role of individual radiologist-specific behavior in issuing such RAI. Methods: This retrospective study included 39,200 patients (median age, 58 years; 21,855 female, 17,315 male, 30 with missing sex information) who underwent 39,200 head and neck CT or MRI examinations, interpreted by 61 radiologists, from June 1, 2021 through May 31, 2022. A natural language processing (NLP) tool with manual review of NLP results was used to identify RAI in report impressions. Interradiologist variation in RAI rates was assessed. A generalized mixed-effects model was used to assess associations between RAI and examination, patient, and radiologist factors. Results: A total of 2946 (7.5%) reports contained an RAI. Individual radiologist RAI rates ranged from 0.8% to 22.0% (median 7.1%, IQR 5.2%-10.2%), representing 27.5-fold difference between minimum and maximum values and 1.8-fold difference between 25th and 75th percentiles. In multivariable analysis, RAI likelihood was higher for CTA than for CT examinations (OR: 1.32), for examinations that included a trainee in report generation (OR: 1.23), and for patients with self-identified race of Black or African American than of White (OR: 1.25); lower for male than female patients (OR: 0.90); and associated with increasing patient age (OR: 1.09 per decade) and inversely associated with radiologist years since training (OR: 0.90 per 5 years). The model accounted for 10.9% of the likelihood of RAI. Of explainable likelihood of RAI, 25.7% was attributable to examination, patient, and radiologist factors; 74.3% was attributable to radiologist-specific behavior. Conclusion: Interradiologist variation in RAI rates for head and neck imaging was substantial. RAI appeared to be more substantially associated with individual radiologist-specific behavior than with measurable systemic factors. Clinical Impact: Quality improvement initiatives, incorporating best practices for incidental findings management, may help reduce radiologist preference-sensitive decision-making in issuing RAI for head and neck imaging and associated care variation.

Point Prevalence Study (PPS) of Antibiotic Usage and Bacterial Culture Rate (BCR) among Secondary Care Hospitals of Small Cities in Central India: Consolidating Indian Evidence.

Objective Indian hospitals (especially government-run public sector hospitals) have a nonexistent antimicrobial stewardship program (AMSP). After successfully initiating AMSPs in tertiary care hospitals of India, the Indian Council of Medical Research envisages implementing AMSP in secondary care hospitals. This study is about the baseline data on antibiotic consumption in secondary care hospitals. Materials and Methods It was a prospective longitudinal observational chart review type of study. Baseline data on antibiotic consumption was captured by a 24-hour point prevalence study of antibiotic usage and bacterial culture rate. The prescribed antibiotics were classified according to the World Health Organization (WHO) Access, Watch, and Reserve classification. All data were collated in Microsoft Excel and summarized as percentages. Results Out of the 864 patients surveyed, overall antibiotic usage was 78.9% (71.5% in low-priority areas vs. 92.2% in high-priority areas). Most of the antibiotic usage was empirical with an extremely low bacterial culture rate (21.9%). Out of the prescribed drugs, 53.1% were from the WHO watch category and 5.5% from the reserve category. Conclusion Even after 5 years of the launch of the national action plan on AMR (NAP-AMR) of India, AMSP is still non-existent in small- and medium-level hospitals in urban cities. The importance of trained microbiologists in the health care system is identified as a fulcrum in combating antimicrobial resistance (AMR); however, their absence in government-run district hospitals is a matter of grave concern and needs to be addressed sooner than later.

Changing Trends in Antimicrobial Susceptibility Patterns of Bloodstream Infection (BSI) in Secondary Care Hospitals of India.

Introduction Bloodstream infection (BSI) and subsequent sepsis are life-threatening medical conditions. The onset of antimicrobial resistance and subsequent multi-drug resistant organisms (MDRO) significantly increase healthcare-associated expenditure with adverse clinical outcomes. The present study was undertaken to identify the trends of BSI in community settings in secondary care hospitals (smaller private hospitals and district hospitals) in the state of Madhya Pradesh in Central India with the support of the Indian Council of Medical Research (ICMR) and National Health Mission, Madhya Pradesh. Methodology The present study was a prospective, longitudinal observational chart review type of study. The study was carried out at 10 secondary care hospitals (eight smaller private hospitals and two government district hospitals) nominated by the State Government as part of the ICMR Antimicrobial Resistance Surveillance and Research Network (AMRSN). The hospitals were nominated depending on the availability of a microbiology laboratory and a full-time microbiologist. Result A total of 6202 blood samples were received from patients with suspected BSI, out of which 693 samples were positive for aerobic culture. Among these, 621 (89.6%) showed bacterial growth and 72 (10.3%) grew Candida species (spp). Out of the 621 bacterial growth samples, Gram-negative bacteria were 406 (65.3%) and Gram-positive bacteria were 215 (34.6%). Among the Gram-negative isolates (406), the predominant isolate was Escherichia coli (115; 28.3%) followed by Klebsiella pneumoniae (109; 26.8%), Pseudomonas aeruginosa (61; 15%), Salmonella spp. (52; 12.8%), Acinetobacter spp. (47; 11.6%) and the other Enterobacter spp. (22; 5.4%). Among the Gram-positive isolates (215), the predominant isolate was Staphylococcus aureus (178; 82.8%) followed by Enterococcus spp. (37; 17.2%). Among the Escherichia coli, third-generation cephalosporin resistance was identified in 77.6%, piperacillin-tazobactam resistance in 45.2%, carbapenem resistance in 23.5% and colistin resistance in 16.5% of cases. Among the Klebsiella pneumoniae, third-generation cephalosporin resistance was identified in 80.7%, piperacillin-tazobactam resistance in 72.8%, carbapenem resistance in 63.3% and colistin resistance in 14% of cases. Among the Pseudomonas aeruginosa, ceftazidime resistance was identified in 61.2%, piperacillin-tazobactam resistance in 55%, carbapenem resistance in 32.8%, and colistin resistance in 38.3% of cases. Among the Acinetobacter spp., piperacillin-tazobactam resistance was identified in 72.7%, carbapenem resistance in 72.3%, and colistin resistance in 9.3% cases. While analyzing the antibiogram for Staphylococcus aureus isolates, methicillin resistance (MRSA) was seen in 70.3% of cases, followed by vancomycin resistance (VRSA) in 8% of cases and linezolid resistance in 8.1%. Among the Enterococcus spp. isolates, linezolid resistance was found in 13.5%, vancomycin resistance (VRE) in 21.6%, and teicoplanin resistance in 29.7% of cases. Conclusion In conclusion, the first-ever study to identify the risk of high-end antibiotics causing significant drug resistance in secondary and tertiary care settings has highlighted the urgent need for more randomized control studies and proactive measures from healthcare authorities and serves as a beacon for future research efforts and underscores the importance of implementing antibiograms to combat the growing threat of antibiotic resistance.

Isolation and Culture of Primary Fibroblasts from Neonatal Murine Hearts to Study Cardiac Fibrosis.

Cardiac fibroblasts are one of the major constituents of a healthy heart. Cultured cardiac fibroblasts are a crucial resource for conducting studies on cardiac fibrosis. The existing methods for culturing cardiac fibroblasts involve complicated steps and require special reagents and instruments. The major problems faced with primary cardiac fibroblast culture are the low yield and viability of the cultured cells and contamination with other heart cell types, including cardiomyocytes, endothelial cells, and immune cells. Numerous parameters, including the quality of the reagents used for the culture, conditions maintained during digestion of the cardiac tissue, composition of the digestion mixture used, and age of the pups used for culture determine the yield and purity of the cultured cardiac fibroblasts. The present study describes a detailed and simplified protocol to isolate and culture primary cardiac fibroblasts from neonatal murine pups. We demonstrate the transdifferentiation of fibroblasts into myofibroblasts through transforming growth factor (TGF)-ß1 treatment, representing the changes in fibroblasts during cardiac fibrosis. These cells can be used to study the various aspects of cardiac fibrosis, inflammation, fibroblast proliferation, and growth.

Palliative care education in an Australian undergraduate pharmacy curriculum: an exploratory descriptive study.

OBJECTIVES: To examine the self-perceived knowledge, confidence and preparedness of undergraduate pharmacy students to provide palliative care. METHODS: A descriptive exploratory analysis was conducted in 2021 at an Australian university involving final-year pharmacy students (n = 200) who were provided with the opportunity to complete a survey on self-perceived knowledge, confidence and preparedness overall and with respect to a range of graduate capabilities which are essential to provide care in palliative care settings. Key capability areas include: communication, showing empathy, making clinical judgements and self-reflection. This was measured using the Palliative Care Curriculum for Undergraduates Questionnaire which was distributed electronically. Descriptive statistics were undertaken and Mann-Whitney U tests were used to explore any differences in outcomes with respect to factors related to demographics, personal experience and education. Thematic analysis was utilised for qualitative data. KEY FINDINGS: Forty-five percent of the student cohort (n = 89) responded, 70% of whom were female, and the median age for students was 22 years. Median scores (interquartile range) were modest for overall self-perceived knowledge: 5.0 (3.0-5.0), confidence: 4.0 (3.0-5.0) and preparedness: 4.0 (2.5-5.0). Students who had participated in learning about palliative care through clinical placements (n = 25, 28%), self-directed learning activities (n = 18, 20%) or case-/problem-based learning (n = 14, 16%) demonstrated a statistically significant increase in overall preparedness (P = 0.017), confidence with specific capabilities including evidence-based practice (P = 0.013), responding to medication queries (P < 0.05) and managing symptoms other than pain (P = 0.018). CONCLUSIONS: Findings suggest students were confident to manage symptoms and medication-related issues but less confident to address distress or discuss sensitive matters with patients and their families. There may be a need for greater exposure and practical experience in palliative care settings.

Brucellosis: epidemiology, pathogenesis, diagnosis and treatment-a comprehensive review.

Background: Brucellosis is a pervasive zoonotic disease caused by various Brucella species. It mainly affects livestock and wildlife and poses significant public health threats, especially in regions with suboptimal hygiene, food safety, and veterinary care standards. Human contractions occur by consuming contaminated animal products or interacting with infected animals. Objective: This study aims to provide an updated understanding of brucellosis, from its epidemiology and pathogenesis to diagnosis and treatment strategies. It emphasizes the importance of ongoing research, knowledge exchange, and interdisciplinary collaboration for effective disease control and prevention, highlighting its global health implications. Methods: Pathogenesis involves intricate interactions between bacteria and the host immune system, resulting in chronic infections characterized by diverse clinical manifestations. The diagnostic process is arduous owing to non-specific symptomatology and sampling challenges, necessitating a fusion of clinical and laboratory evaluations, including blood cultures, serological assays, and molecular methods. Management typically entails multiple antibiotics, although the rise in antibiotic-resistant Brucella strains poses a problem. Animal vaccination is a potential strategy to curb the spread of infection, particularly within livestock populations. Results: The study provides insights into the complex pathogenesis of brucellosis, the challenges in its diagnosis, and the management strategies involving antibiotic therapy and animal vaccination. It also highlights the emerging issue of antibiotic-resistant Brucella strains. Conclusions: In conclusion, brucellosis is a significant zoonotic disease with implications for public health. Efforts should be directed towards improved diagnostic methods, antibiotic stewardship to combat antibiotic resistance, and developing and implementing effective animal vaccination programs. Interdisciplinary collaboration and ongoing research are crucial for addressing the global health implications of brucellosis.

Tumor-intrinsic SIRPA promotes sensitivity to checkpoint inhibition immunotherapy in melanoma.

Checkpoint inhibition immunotherapy has revolutionized cancer treatment, but many patients show resistance. Here we perform integrative transcriptomic and proteomic analyses on emerging immuno-oncology targets across multiple clinical cohorts of melanoma under anti-PD-1 treatment, on both bulk and single-cell levels. We reveal a surprising role of tumor-intrinsic SIRPA in enhancing antitumor immunity, in contrast to its well-established role as a major inhibitory immune modulator in macrophages. The loss of SIRPA expression is a marker of melanoma dedifferentiation, a key phenotype linked to immunotherapy efficacy. Inhibition of SIRPA in melanoma cells abrogates tumor killing by activated CD8+ T cells in a co-culture system. Mice bearing SIRPA-deficient melanoma tumors show no response to anti-PD-L1 treatment, whereas melanoma-specific SIRPA overexpression significantly enhances immunotherapy response. Mechanistically, SIRPA is regulated by its pseudogene, SIRPAP1. Our results suggest a complicated role of SIRPA in the tumor ecosystem, highlighting cell-type-dependent antagonistic effects of the same target on immunotherapy.

Sirtuin 6 inhibition protects against glucocorticoid-induced skeletal muscle atrophy by regulating IGF/PI3K/AKT signaling.

Chronic activation of stress hormones such as glucocorticoids leads to skeletal muscle wasting in mammals. However, the molecular events that mediate glucocorticoid-induced muscle wasting are not well understood. Here, we show that SIRT6, a chromatin-associated deacetylase indirectly regulates glucocorticoid-induced muscle wasting by modulating IGF/PI3K/AKT signaling. Our results show that SIRT6 levels are increased during glucocorticoid-induced reduction of myotube size and during skeletal muscle atrophy in mice. Notably, overexpression of SIRT6 spontaneously decreases the size of primary myotubes in a cell-autonomous manner. On the other hand, SIRT6 depletion increases the diameter of myotubes and protects them against glucocorticoid-induced reduction in myotube size, which is associated with enhanced protein synthesis and repression of atrogenes. In line with this, we find that muscle-specific SIRT6 deficient mice are resistant to glucocorticoid-induced muscle wasting. Mechanistically, we find that SIRT6 deficiency hyperactivates IGF/PI3K/AKT signaling through c-Jun transcription factor-mediated increase in IGF2 expression. The increased activation, in turn, leads to nuclear exclusion and transcriptional repression of the FoxO transcription factor, a key activator of muscle atrophy. Further, we find that pharmacological inhibition of SIRT6 protects against glucocorticoid-induced muscle wasting in mice by regulating IGF/PI3K/AKT signaling implicating the role of SIRT6 in glucocorticoid-induced muscle atrophy.

Clinico-Epidemio-Microbiological Exploratory Review Among COVID-19 Patients with Secondary Infection in Central India.

Purpose: Secondary infections (SI) in COVID-19 have been documented from 3.6% to 72% in various studies with mortality ranging from 8.1% to 57.6%. There is a gap in knowledge for clinico-epidemio-microbilogical association among COVID-19 patients with concomitant SI. Patients and Methods: This is a retrospective chart review, in central India. The study was undertaken for hospitalized adult patients during 1st June 2020 to 30th November 2020, with laboratory proven COVID-19 infection and secondary infection. Results: Out of the total 2338 number of patients, only 265 (11.3%) patients were investigated for microbiological identification of SI. Male gender was predominant (76.8%) and the mean age was 53.7 ± 17.8 years. Only 3.5% (82/2338) of patients were having microbiologically confirmed (bacterial or fungal) SI. The overall mortality was 50.9% (54/82) with a differential mortality of 88.8% (48/54) in high-priority areas and 21.4% (6/28) in low-priority areas. Blood was the most commonly investigated sample (56%) followed by urine (20.7%) and respiratory secretion (15.8%). A. baumanii complex (20/82, 24.3%) was the most common bacteria isolated followed by K. pneumonia (12/82, 14.6%) and E. coli (11/82, 13.4%). Candida spp. (20/82, 24.3%) was the most common fungal pathogen isolated. Sixty percent (12/20) of Acinetobacter spp. were carbapenam-resistant and 70.3% of Enterobacterales were carbapenam-resistant. Fluconazole resistant Candid a spp. was isolated only in 10% (2/20) of cases. Diabetes was the most common co-morbidity 54.8% (45/82) followed by hypertension (41.4%) and chronic heart disease (13.4%). The negative predictors of secondary infections are urinary catheterization, placement of central line and mechanical ventilation (invasive and non-invasive). Conclusion: There is an urgent need of better anti-microbial stewardship practices in India (institutional and extra institutional) for curtailment of secondary infection rates particularly among COVID-19 patients.

Impact of an Anti-Microbial Stewardship Program on Targeted Antimicrobial Therapy in a Tertiary Care Health Care Institute in Central India.

Introduction Antimicrobial resistance (AMR) has become a global pandemic. In order to identify this menace, World Health Organisation (WHO) has developed the Global Action Plan on AMR (GAP AMR). Antimicrobial stewardship programs (AMSP) have been identified as a decisive tool for combating AMR. One of the most efficient measures of these programs has been the implementation of point prevalence surveys (PPS) of antibiotic usage and subsequent audit feedback. The present study was undertaken to identify the impact of AMSP on curtailing of empirical usage of antibiotics and the augmentation of targeted therapy.  Methods It is an observational, cross-sectional study comprising 1396 patients. The microbiology culture details and anti-microbial-sensitivity results were recorded. Antibiotic prescriptions were recorded in each patient during their hospital stay. Result Out of 1396 patients treated over four quarters (Q1-Q4), 711 (50.9%) patients were on antibiotics, and among them, only 415 patients were subjected to any microbiological cultures with an overall bacterial culture rate (BCR) of 58.3%, and 296 patients (41.6%) were treated with antibiotics empirically without sending any samples for bacterial culture. There was a statistically significant rise in BCR from 47.3% in the first quarter to 77.6% in the fourth quarter. Sending specimens for blood culture increased significantly from 29.2% in Q1 to 37.6% in Q4. After receiving culture reports, 72.3% of cases continued with the same antibiotic, the antibiotic was changed in 19.9% of cases, and the antibiotic was stopped in 7.8% of cases. Conclusion There was a strong positive impact of AMSP in curtailment of empirical usage of antibiotics and augmenting targeted therapy as evidenced by the significant rise in BCR over Q1-Q4 PPS as well as a significant rise in ordering for blood culture over the same time period.

Practice of antimicrobial stewardship in a government hospital of India and its impact on extended point prevalence of antibiotic usage.

BACKGROUND: Antimicrobial resistance (AMR) is a global concern requiring immediate attention. Among many proven measures of decreasing AMR, practice of antimicrobial stewardship is the lowest hanging which can be adapted with negligible financial implications. METHODS: This is a case record based extended cross-sectional type of observational operation research study conducted at an institute of national importance established by Government of India. Point prevalence of antibiotic usage among the patients admitted in the hospital, on four different days in four different quarters of a year was done to study the impact of antimicrobial stewardship program (AMSP). RESULTS: A cumulative 711 patients were exposed on antibiotics among 1396 study participants. There was a significant decrease in antibiotic consumption across the 1st and 4th quarter. The average antibiotic usage was 50.9% (61.75, 60%, 48.4%, and 39% respectively in the 1st to 4th quarter). Among the total number of patients, intravenous antibiotic usage was 47.9% (60.71%, 58.4%, 44.9%, and 34.2% respectively in 1st to 4th quarter). Among the newly admitted patients, the consumption of antibiotic usage decreased from 45.9% to 25.7%. Among the intravenous antibiotics, the top 10 consumed antibiotics were 3rd generation cephalosporin (39.8%), aminoglycoside (14.8%), amoxicillin/amoxy-clav (12.5%), piperacillin-tazobactum (8.5%), carbapenams (6.6%), cefuroxime (6.4%), quinolones (4.3%), vancomycin/linezolid (4.1%), colistin (0.8%), and others (0.8%). CONCLUSION: Government run hospitals can run low budget antimicrobial stewardship program with sustainable impact on antibiotic consumption. For a successful AMSP, it requires change in attitude, commitment, and administrative support rather than a huge financial support.

Bone tissue engineering techniques, advances and scaffolds for treatment of bone defects.

Bone tissue engineering (BTE) aims to develop strategies to regenerate damaged or diseased bone using a combination of cells, growth factors, and biomaterials. This article highlights recent advances in BTE, with particular emphasis on the role of the biomaterials as scaffolding material to heal bone defects. Studies encompass the utilization of bioceramics, composites, and myriad hydrogels that have been fashioned by injection molding, electrospinning, and 3D bioprinting over recent years, with the aim to provide an insight into the progress of BTE along with a commentary on their scope and possibilities to aid future research. The biocompatibility and structural efficacy of some of these biomaterials are also discussed.

A Model for Studying the Biomechanical Effects of Varying Ratios of Collagen Types I and III on Cardiomyocytes.

PURPOSE: To develop a novel model composed solely of Col I and Col III with the lower and upper limits set to include the ratios of Col I and Col III at 3:1 and 9:1 in which the structural and mechanical behavior of the resident CM can be studied. Further, the progression of fibrosis due to change in ratios of Col I:Col III was tested. METHODS: Collagen gels with varying Col I:Col III ratios to represent a healthy (3:1) and diseased myocardial tissue were prepared by manually casting them in wells. Absorbance assay was performed to confirm the gelation of the gels. Rheometric analysis was performed on each of the collagen gels prepared to determine the varying stiffnesses and rheological parameters of the gels made with varying ratios of Col I:Col III. Second Harmonic Generation (SHG) was performed to observe the 3D characterization of the collagen samples. Scanning Electron microscopy was used for acquiring cross sectional images of the lyophilized collagen gels. AC16 CM (human) cell lines were cultured in the prepared gels to study cell morphology and behavior as a result of the varying collagen ratios. Cellular proliferation was studied by performing a Cell Trace Violet Assay and the applied force on each cell was measured by means of Finite Element Analysis (FEA) on CM from each sample. RESULTS: Second harmonic generation microscopy used to image Col I, displayed a decrease in acquired image intensity with an increase in the non-second harmonic Col III in 3:1 gels. SEM showed a fiber-rich structure in the 3:1 gels with well-distributed pores unlike the 9:1 gels or the 1:0 controls. Rheological analysis showed a decrease in substrate stiffness with an increase of Col III, in comparison with other cases. CM cultured within 3:1 gels exhibited an elongated rod-like morphology with an average end-to-end length of 86 ± 28.8 µm characteristic of healthy CM, accompanied by higher cell growth in comparison with other cases. Finite element analysis used to estimate the forces exerted on CM cultured in the 3:1 gels, showed that the forces were well dispersed, and not concentrated within the center of cells, in comparison with other cases. CONCLUSION: This study model can be adopted to simulate various biomechanical environments in which cells crosstalk with the Collagen-matrix in diseased pathologies to generate insights on strategies for prevention of fibrosis.

Methods for histological characterization of cryo-induced myocardial infarction in a rat model.

Ligation of the left anterior descending (LAD) coronary artery has been commonly employed to induce myocardial infarction (MI) in animals; however, it is known to pose setbacks in the form of cardiac arrhythmias and unpredictable areas of necrotic damage. Cryo-infarction is an alternate method that has been adopted to create a reproducible model of a myocardial injury. In this study, Sprague-Dawley rats were subjected to thoracotomy followed by cryo-induced infarction of the heart, while the control-sham group was only subjected to thoracotomy following which the heart was collected from all animals. Tissue sections were stained with hematoxylin and eosin and analyzed to determine cardiac muscle density, fiber length, and fiber curvature. Observations revealed reduced muscle density, cardiac fiber length, and distorted fibers in infarcted tissue sections. Gomori's Trichrome staining was performed on tissue sections to study the effects of post MI on collagen, which showed enhanced intensity of collagen staining indicating fibrosis for the experimental models as compared to the sham models, an established consequence to myocardial injury. Immunohistochemical staining of the tissue sections with DAPI and connexin-43 (Cx-43) revealed that there was reduced DAPI staining and a less pronounced expression of Cx-43 in the experimental samples as compared to the sham samples. Results implied significant cell damage resulting from the cryo-infarction, subsequently disrupting and disaggregating the functional Cx-43 junction in cardiac myocytes, which is essential for normal and healthy cardiac physiology and function. This quantitative histological study of cryo-induced MI in a rat model can aid others attempting to optimize MI models in rats via cryo-injury, to study cardiac disease progression, and to aid in the construction of engineered cardiac tissues.

Hydrogel scaffolds with elasticity-mimicking embryonic substrates promote cardiac cellular network formation.

Hydrogels are a class of biomaterials used for a wide range of biomedical applications, including as a three-dimensional (3D) scaffold for cell culture that mimics the extracellular matrix (ECM) of native tissues. To understand the role of the ECM in the modulation of cardiac cell function, alginate was used to fabricate crosslinked gels with stiffness values that resembled embryonic (2.66 ± 0.84 kPa), physiologic (8.98 ± 1.29 kPa) and fibrotic (18.27 ± 3.17 kPa) cardiac tissues. The average pore diameter and hydrogel swelling were seen to decrease with increasing substrate stiffness. Cardiomyocytes cultured within soft embryonic gels demonstrated enhanced cell spreading, elongation, and network formation, while a progressive increase in gel stiffness diminished these behaviors. Cell viability decreased with increasing hydrogel stiffness. Furthermore, cells in fibrotic gels showed enhanced protein expression of the characteristic cardiac stress biomarker, Troponin-I, while reduced protein expression of the cardiac gap junction protein, Connexin-43, in comparison to cells within embryonic gels. The results from this study demonstrate the role that 3D substrate stiffness has on cardiac tissue formation and its implications in the development of complex matrix remodeling-based conditions, such as myocardial fibrosis.

Targeting metabolic syndrome with phytochemicals: Focus on the role of molecular chaperones and hormesis in drug discovery.

Adaptive cellular stress response confers stress tolerance against inflammatory and metabolic disorders. In response to metabolic stress, the key mediator of cellular adaptation and tolerance is a class of molecules called the molecular chaperones (MCs). MCs are highly conserved molecules that play critical role in maintaining protein stability and functionality. Hormesis in this context is a unique adaptation mechanism where a low dose of a stressor (which is toxic at high dose) confers a stress-resistant adaptive cellular phenotype. Hormesis can be observed at different level of biological organization at various measurable endpoints. The MCs are believed to play a key role in adaptation during hormesis. Several phytochemicals are known for their hormetic response and are called phytochemical hormetins. The role of phytochemical-mediated hormesis on the adaptive cellular processes is proposed as a potential therapeutic approach to target inflammation associated with metabolic syndrome. However, the screening of phytochemical hormetins would require a paradigm shift in the methods currently used in drug discovery.

Evolution of Radicals from the Photolysis of High Ionic Strength Alkaline Nitrite Solutions.

Reactive nitrogen species (RNS), along with reactive oxygen species (ROS), are significant products from radiolysis in solution. While much research has been focused on biological systems, these species are also important products in the autoradiolysis that occurs in nuclear waste. Here, we determine the correlation between solution constituents, particularly nitrite, and radical products in highly alkaline solutions relevant to liquid waste. Because these radicals tend to be very short-lived, we employ spin trapping in conjunction with electron paramagnetic resonance (EPR) to detect them and quantify their production. Most spin traps do not function in these conditions (>1 M NaOH); however, nitroalkanes such as nitromethane will act as spin traps in their aci form, which is dominant at high pH. To restrict the products to those originating from nitrite, we use 280-480 nm UV light to generate radicals, avoiding products from the photolysis of water. Under these circumstances, nitric oxide, nitrite radicals, and hydroxyl radicals are detected, and the trends with the concentration of the constituents of the solutions are tracked. These include nitrite, nitrate, hydroxide, and carbonate. We find that, while the equilibrium shifts with increasing pH from hydroxyl radicals to the more slowly reacting oxide radicals, the production of nitrite radicals does not decrease.

Sirtuin 6 deficiency transcriptionally up-regulates TGF-ß signaling and induces fibrosis in mice.

Caloric restriction has been associated with increased life span and reduced aging-related disorders and reduces fibrosis in several diseases. Fibrosis is characterized by deposition of excess fibrous material in tissues and organs and is caused by aging, chronic stress, injury, or disease. Myofibroblasts are fibroblast-like cells that secrete high levels of extracellular matrix proteins, resulting in fibrosis. Histological studies have identified many-fold increases of myofibroblasts in aged organs where myofibroblasts are constantly generated from resident tissue fibroblasts and other cell types. However, it remains unclear how aging increases the generation of myofibroblasts. Here, using mouse models and biochemical assays, we show that sirtuin 6 (SIRT6) deficiency plays a major role in aging-associated transformation of fibroblasts to myofibroblasts, resulting in tissue fibrosis. Our findings suggest that SIRT6-deficient fibroblasts transform spontaneously to myofibroblasts through hyperactivation of transforming growth factor ß (TGF-ß) signaling in a cell-autonomous manner. Importantly, we noted that SIRT6 haploinsufficiency is sufficient for enhancing myofibroblast generation, leading to multiorgan fibrosis and cardiac dysfunction in mice during aging. Mechanistically, SIRT6 bound to and repressed the expression of key TGF-ß signaling genes by deacetylating SMAD family member 3 (SMAD3) and Lys-9 and Lys-56 in histone 3. SIRT6 binding to the promoters of genes in the TGF-ß signaling pathway decreased significantly with age and was accompanied by increased binding of SMAD3 to these promoters. Our findings reveal that SIRT6 may be a potential candidate for modulating TGF-ß signaling to reduce multiorgan fibrosis during aging and fibrosis-associated diseases.

Fabrication of Surfactant-Dispersed HiPco Single-Walled Carbon Nanotube-Based Alginate Hydrogel Composites as Cellular Products.

In this study, we designed, synthesized, and characterized ultrahigh purity single-walled carbon nanotube (SWCNT)-alginate hydrogel composites. Among the parameters of importance in the formation of an alginate-based hydrogel composite with single-walled carbon nanotubes, are their varying degrees of purity, their particulate agglomeration and their dose-dependent correlation to cell viability, all of which have an impact on the resultant composite's efficiency and effectiveness towards cell-therapy. To promote their homogenous dispersion by preventing agglomeration of the SWCNT, three different surfactants-sodium dodecyl sulfate (SDS-anionic), cetyltrimethylammonium bromide (CTAB-cationic), and Pluronic F108 (nonionic)-were utilized. After mixing of the SWCNT-surfactant with alginate, the mixtures were cross-linked using divalent calcium ions and characterized using Raman spectroscopy. Rheometric analysis showed an increase in complex viscosity, loss, and storage moduli of the SWCNT composite gels in comparison with pure alginate gels. Scanning electron microscopy revealed the presence of a well-distributed porous structure, and all SWCNT-gel composites depicted enhanced electrical conductivity with respect to alginate gels. To characterize their biocompatibility, cardiomyocytes were cultured atop these SWCNT-gels. Results comprehensively implied that Pluronic F108 was most efficient in preventing agglomeration of the SWCNTs in the alginate matrix, leading to a stable scaffold formation without posing any toxicity to the cells.