Detection of Cyanide in a Decomposed Exhumed Body: A Case Report.

Cyanide is a lethal poison that induces immediate fatality. Infrequently employed as a homicidal poison, it is not an ideal choice for homicide as it causes a 'dramatic' death causing suspicion among others. Cyanide is a rapidly metabolized poison that also rapidly disintegrates after death, posing challenges for chemical analysis, particularly when dealing with decomposed bodies. Detection of cyanide from a decomposed body is infrequent. A suspected case of intentional poisoning resulting in death was interred without conducting a postmortem examination. The exhumation process revealed the presence of hydrogen cyanide in the postmortem fluids collected from the body cavities three years after interment.

Comparing the posture and comfort of anaesthesiologists during laryngoscopy and tracheal intubation in the head-elevated laryngoscopy position in supine position and with a 25° backup: A randomised clinical crossover trial.

Background and Aims: The head-elevated laryngoscopy position (HELP) and a 25° backup have been proposed to enhance glottic visualisation, yet concerns about ergonomic discomfort hinder their widespread adoption. This study compares the comfort and posture adopted by anaesthesiologists while performing laryngoscopy and tracheal intubation with patients in HELP while in a supine position or with 25° backup. Methods: The study included 48 patients aged 18-60 years with normal airways and 12 experienced anaesthesiologists. Patients were randomised into two groups using permuted block randomisation. Anaesthesiologists performed laryngoscopy and intubation in supine HELP and 25° backup HELP positions. Anaesthesiologist's posture was determined by measuring the angles of neck, wrist, elbow, back and knee joints, which were compared using Student's t-test, and subjective comfort assessed on a Likert scale was compared using the Chi-square test. As mentioned by the anaesthesiologist, Cormack- Lehane grading was also noted and compared using a Chi-square test between groups, taking a P value <0.05 as significant. Results: Both positions demonstrated comparable anaesthesiologist posture (P = 0.919) and comfort (P = 0.644). However, the 25° backup HELP positions significantly improved Cormack-Lehane grades, with 68% achieving grade 1 compared to 31% in the supine HELP group (P = 0.012). Haemodynamic stability and tracheal intubation time showed no significant differences between the groups (P = 0.475 and 0.117, respectively), and no complications were reported in either group. Conclusion: Anaesthesiologists' posture and comfort during laryngoscopy and tracheal intubation are similar between supine and 25° backup in patients with easy airways.

18F-FDG PET/CT Findings in a Rare Case of Paraneoplastic Vestibulocerebellar Syndrome Associated With Isolated Antiamphiphysin Antibodies.

ABSTRACT: Paraneoplastic cerebellar degeneration (PCD) is an immune-mediated neurological disease characterized by adaptive immune response against onconeural antigens physiologically expressed in the cerebellum. It is characterized by presence of highly specific onconeural autoantibodies such as anti-Yo, anti-Hu, anti-Ri, and anti-Ma2 in the serum and cerebrospinal fluid as diagnostic biomarkers. Antiamphiphysin autoantibody-related paraneoplastic encephalitis is a less commonly seen autoimmune neurological disorder usually presenting as stiff person syndrome. We present an unusual case of isolated antiamphiphysin antibody-related PCD presenting as vestibulocerebellar syndrome with associated sensorineural hearing loss and sensory neuropathy. FDG PET helped in topographical localization of brain lesion along with early detection of extragonadal germ cell tumor in the retroperitoneum.

On the folding of a structurally complex protein to its metastable active state.

For successful protease inhibition, the reactive center loop (RCL) of the two-domain serine protease inhibitor, α1-antitrypsin (α1-AT), needs to remain exposed in a metastable active conformation. The α1-AT RCL is sequestered in a ß-sheet in the stable latent conformation. Thus, to be functional, α1-AT must always fold to a metastable conformation while avoiding folding to a stable conformation. We explore the structural basis of this choice using folding simulations of coarse-grained structure-based models of the two α1-AT conformations. Our simulations capture the key features of folding experiments performed on both conformations. The simulations also show that the free energy barrier to fold to the latent conformation is much larger than the barrier to fold to the active conformation. An entropically stabilized on-pathway intermediate lowers the barrier for folding to the active conformation. In this intermediate, the RCL is in an exposed configuration, and only one of the two α1-AT domains is folded. In contrast, early conversion of the RCL into a ß-strand increases the coupling between the two α1-AT domains in the transition state and creates a larger barrier for folding to the latent conformation. Thus, unlike what happens in several proteins, where separate regions promote folding and function, the structure of the RCL, formed early during folding, determines both the conformational and the functional fate of α1-AT. Further, the short 12-residue RCL modulates the free energy barrier and the folding cooperativity of the large 370-residue α1-AT. Finally, we suggest experiments to test the predicted folding mechanism for the latent state.

Comparison of Pioglitazone and Metformin Efficacy against Glucocorticoid Induced Atherosclerosis and Hepatic Steatosis in Insulin Resistant Rats.

INTRODUCTION: Insulin Resistance is a major cause of Atherosclerosis (AS) and Non Alcoholic Fatty Liver Disease (NAFLD). These lipid alterations in blood vessels and liver may progress to cardiovascular abnormalities and cirrhosis respectively. Drugs like pioglitazone (PIO) and metformin (MET) are effective insulin sensitizers used in T2DM. But their efficacy and tolerability needs to be compared in IR associated abnormalities. AIM: To compare the efficacy of PIO and MET in glucocorticoid induced AS, Hepatic Steatosis (HS) and IR in albino rats. MATERIALS AND METHODS: Male Wistar albino rats were randomized into four groups (n=6). Group 1 (Normal control) rats consumed 2% gum acacia orally for 12 days. Group 2 {dexamethasone (DEX) control} rats were administered 2% gum acacia orally for 12 days and DEX (8 mg/kg) intraperitoneally (i.p.) from 7th to 12th day during the study period. Group 3 and 4 (PIO and MET control) rats received oral administration of PIO (45 mg/kg) and MET (1000 mg/kg) for 12 days respectively. Both groups were treated with DEX (8 mg/kg/i.p.) from 7th to 12th day during the study period. On last day, fasting blood was collected and rats were sacrificed by cervical dislocation; aorta and liver tissues were isolated for the histopathological examination. Body weight, liver weight and liver volume were measured. Blood samples were processed for biochemical parameters. The data were analysed by One-way Analysis of variance (ANOVA) followed by Scheffe's multiple comparison post-hoc test. The statistical significance was assumed at p<0.05. RESULTS: Our results established the possible role of DEX in the development of AS and HS. Histopathological examination of Group 2 rats treated with DEX showed a marked lipid accumulation in the aorta and liver. Administration of MET and PIO resulted in partial to complete restoration of DEX induced fatty changes in aorta and liver. Both drugs significantly (p<0.05) prevented the elevation of insulin, lipid, glucose levels, liver weight and liver volume in DEX treated rats. They had significantly (p<0.05) improved body weight and insulin sensitivity. However, PIO was highly significant (p<0.05) compared to MET in reducing DEX induced IR complications. CONCLUSION: These findings suggest that PIO was more effective insulin sensitizer compared to MET in reducing AS, HS and IR induced by glucocorticoids.

Capturing the Membrane-Triggered Conformational Transition of an α-Helical Pore-Forming Toxin.

Escherichia coli cytolysin A (ClyA) is an α-helical pore-forming toxin (PFT) which lyses target cells by forming membrane permeabilizing pores. The rate-determining step of this process is the conversion of the soluble ClyA monomer into a membrane inserted protomer. We elucidate the mechanism of this conformational transition using molecular dynamics simulations of coarse-grained models of ClyA and a membrane. We find that a membrane is necessary for the conformational conversion because membrane-protein interactions counteract the loss of the many intraprotein hydrophobic interactions that stabilize the membrane-inserting segments in the ClyA monomer. Of the two membrane-inserting segments, the flexible and highly hydrophobic ß-tongue inserts first while the insertion of helix αA1 is membrane assisted. We conclude that the ß-tongue is designed to behave as a quick-response membrane sensor, while helix αA1 improves target selectivity for cholesterol-containing cell membranes by acting as a fidelity check.

Using the folding landscapes of proteins to understand protein function.

Proteins fold on a biologically-relevant timescale because of a funnel-shaped energy landscape. This landscape is sculpted through evolution by selecting amino-acid sequences that stabilize native interactions while suppressing stable non-native interactions that occur during folding. However, there is strong evolutionary selection for functional residues and these cannot be chosen to optimize folding. Their presence impacts the folding energy landscape in a variety of ways. Here, we survey the effects of functional residues on folding by providing several examples. We then review how such effects can be detected computationally and be used as assays for protein function. Overall, an understanding of how functional residues modulate folding should provide insights into the design of natural proteins and their homeostasis.

Dose Dependent Hepatic and Endothelial Changes in Rats Treated with Dexamethasone.

AIMS AND OBJECTIVES: To study the effect of dexamethasone on liver and endothelium, and to determine the optimum dose which induces the abnormal changes in liver and endothelium in Wistar rats. MATERIALS AND METHODS: Albino Wistar rats were divided into 7 groups (n=6). Control group rats received normal saline. Graded doses of dexamethasone (0.5,1,2,4,8 and 16mg/kg/ i.p.) was administered to the groups for six days. Liver and aorta were dissected at the end of the study and examined for histopathological changes under microscope. RESULTS: Intraperitoneal administration of dexamethasone (4,8 and 16mg/kg) for six days resulted in fatty changes in liver and same doses have shown thickening of endothelial layers in aorta, in comparison to control group. There were not much significant changes seen in low doses of dexamethasone (0.5, 1 and 2mg/kg). CONCLUSION: It is concluded that the acute high doses of dexamethasone (4,8 and 16mg/kg) for six days caused hepatic steatosis and showed mild to moderate arteriosclerosis in aorta. These changes may be secondary consequences of insulin resistance. Hence, it can be used as new animal model to screen the various plants and medicines in the treatment of insulin resistance.

Structural Perturbations Present in the Folding Cores of Interleukin-33 and Interleukin-1ß Correlate to Differences in Their Function.

The interleukin-1 cytokines belong to the ß-trefoil fold family and play a key role in immune responses to infections and injury. We simulate the structure-based models of two interleukin-1 cytokines, IL-33 and IL-1ß, and find that IL-33 has a lower barrier to folding than IL-1ß. We then design the folding motif (FM) of the ß-trefoil fold and identify structural deviations of IL-33 and IL-1ß from this FM. In previous work, we found that structural deviations from the FM that are large enough to lower folding free energy barriers were part of ligand binding sites. In contrast, we find that structural perturbations in IL-33 and IL-1ß which reduce the folding free energy barrier are located in the folding core and do not bind ligands. In both proteins, such core residues are interleaved with surface residues which are proximal to receptor binding sites. However, IL-33 has a lower folding barrier because its core perturbations are larger than those in IL-1ß. In order to understand the role of these core perturbations, we perform atomistic simulations of both proteins and find that the larger core perturbations may allow IL-33 to communicate signals differently across the protein. Integrating previous data, we also hypothesize that the larger IL-33 core perturbations may help accommodate its more charged binding site and may also aid in its inactivation by caspase-mediated cleavage. Together, our results suggest that protein folding landscapes are modulated not only by larger functional features such as binding sites but also by the details of protein function and fate. Furthermore, a comparative study of such landscapes may be a facile way to identify subtle differences in allosteric connectivity between two similar proteins.

In the multi-domain protein adenylate kinase, domain insertion facilitates cooperative folding while accommodating function at domain interfaces.

Having multiple domains in proteins can lead to partial folding and increased aggregation. Folding cooperativity, the all or nothing folding of a protein, can reduce this aggregation propensity. In agreement with bulk experiments, a coarse-grained structure-based model of the three-domain protein, E. coli Adenylate kinase (AKE), folds cooperatively. Domain interfaces have previously been implicated in the cooperative folding of multi-domain proteins. To understand their role in AKE folding, we computationally create mutants with deleted inter-domain interfaces and simulate their folding. We find that inter-domain interfaces play a minor role in the folding cooperativity of AKE. On further analysis, we find that unlike other multi-domain proteins whose folding has been studied, the domains of AKE are not singly-linked. Two of its domains have two linkers to the third one, i.e., they are inserted into the third one. We use circular permutation to modify AKE chain-connectivity and convert inserted-domains into singly-linked domains. We find that domain insertion in AKE achieves the following: (1) It facilitates folding cooperativity even when domains have different stabilities. Insertion constrains the N- and C-termini of inserted domains and stabilizes their folded states. Therefore, domains that perform conformational transitions can be smaller with fewer stabilizing interactions. (2) Inter-domain interactions are not needed to promote folding cooperativity and can be tuned for function. In AKE, these interactions help promote conformational dynamics limited catalysis. Finally, using structural bioinformatics, we suggest that domain insertion may also facilitate the cooperative folding of other multi-domain proteins.

Evaluation of antiulcerogenic potential of antioxidant α-tocopherol in pylorus-ligated albino rats.

BACKGROUND: Oxidative free radicals and lipid peroxidation mediate gastric injury. α-Tocopherol is a redox agent with biological and antioxidant property, hence, may provide ulcer protection. METHODS: Pylorus-ligated Shay rats (n=6) were used as the experimental gastric ulcer animal model. The rats were divided into three groups. Group I received saline (5 mL/kg), Group II α-tocopherol (12.5 mg/kg), and Group III omeprazole (3.6 mg/kg), orally daily for 5 days prior to ulcerogenic challenge. Nineteen hours after the challenge, the rats were sacrificed and their stomachs isolated and studied for degree of gastric injury. Formed gastric juice was collected for measurement of volume, titrimetric estimation of free and total acidity, and total acid output by the conventional methods. The ulcer index and total acid outputs were calculated. RESULTS: α-Tocopherol exerted significant (p<0.05) antiulcer activity (the ulcer index was reduced to 7.4 ± 1.0 from the control value of 19.8 ± 4.1). α-Tocopherol also significantly reduced free and total acidity, gastric juice volume, and total acid output (p<0.01). The results were analyzed by ANOVA and Scheffe's multiple comparison test. CONCLUSIONS: The study demonstrates that α-tocopherol has significant antiulcer activity. It, perhaps, acts by decreasing hydrochloric acid output.