Caffeine, a naturally occurring purine-based alkaloid, is the most consumed psychostimulant worldwide. Since caffeine pharmacokinetics shows extreme interindividual variability, it is not easy to establish its toxic dose. Only a few cases of death due to acute caffeine intoxication have been described so far, the majority of which attributable to massive assumption of caffeine-based medications. We present a case of acute caffeine overdose due to ingestion of pure caffeine. The extremely high blood concentration of caffeine determined a strong cardiovascular response, leading to fatal arrhythmia, as supported by histological evidence of myocardial injury. Quantitation of catecholamines and their metabolites in urine samples was performed and showed level near the highest limit of normal ranges for norepinephrine and high level of epinephrine. Contraction band is a pathological modification of the myocell caused by the catecholaminergic action and can occur in conditions of alteration due to the interaction between calcium and catecholamines. We demonstrated the β1-adrenoceptor involvement in our fatal case by immunohistochemical analysis.

β1-Adrenoreceptor (ADRB1) genetic polymorphisms are widely studied for susceptibility to many cardiovascular diseases such as essential hypertension. However, the mRNA expression of ADRB1 is rarely studied.
A case-control pilot study with 292 hypertensives and 324 controls was designed to evaluate the role of the Ser49Gly and Arg389Gly, which are commonly studied single nucleotide polymorphisms (SNP), in the mRNA levels of ADRB1, in conjunction with its genetic predisposition to essential hypertension.
Differential expression of ADRB1 mRNA was seen between hypertensives and controls (p<0.01) based on genetic variants of Ser49Gly. Among hypertensive subjects, Ser49Ser and Gly49Gly were highly expressed in comparison to Ser49Gly (p<0.05 and p<0.01, respectively), whereas genetic variants of Arg389Gly did not demonstrate any such variations. We found no association between the ADRB1 SNPs viz., Ser49Gly and Arg389Gly and essential hypertension.
The increased mRNA levels of Gly49Gly may indicate a plausible role in the interindividual variations in drug response. Further, ADRB1 polymorphisms did not contribute to the genetic risk of essential hypertension. Studies with larger sample size are warranted to confirm these observations in the South Indian population.

Takotsubo cardiomyopathy (TCM), also known as \"broken heart syndrome\", is a type of heart failure characterized by transient ventricular dysfunction in the absence of obstructive coronary lesions. Although associated with increased levels of catecholamines, pathophysiological mechanisms are unknown. Relapses and family heritability indicate a genetic predisposition. Several small studies have investigated associations between three different loci; the β1-adrenic receptor (ADRB1), G-protein-coupled receptor kinase 5 (GRK5), Bcl-associated athanogene 3 (BAG3) and TCM but no consensus has been reached.
Participants were recruited using the Swedish Coronary Angiography and Angioplasty Register (SCAAR). TCM patients without coronary artery disease (CAD)(n = 258) were identified and age- and sex-matched subjects with (n = 164) and without (n = 243) CAD were selected as controls. DNA was isolated from saliva and genotyped for candidate single nucleotide polymorphisms in the ADRB1, GRK5 and BAG3 genes. Allele frequencies and Odds Ratios (OR) with 95% Confidence Intervals (CI) for the investigated polymorphisms were compared, respectively calculated for TCM patients and controls.
There were no differences in allele frequencies between TCM patients and controls. OR (CI) for TCM patients having at least one minor allele using controls as reference were 1.07 (0.75-1.55) for ADRB1, 0.45 (0.11-1.85) for GRK5 and 1.27 (0.74-2.19) for BAG3.
By genotyping a large takotsubo cohort, we demonstrate a lack of association between candidate SNPs in the ADRB1, GRK5 and BAG3 genes, earlier suggested to contribute to TCM. Our result indicates a need to expand the search for new genetic candidates contributing to TCM.

The spectacular advances in G-protein-coupled receptor (GPCR) structure determination have opened up new possibilities for structure-based GPCR ligand discovery. The structure-based prediction of whether a ligand stimulates (full/partial agonist), blocks (antagonist), or reduces (inverse agonist) GPCR signaling activity is, however, still challenging. A total of 31 β1 (β1R) and β2 (β2R) adrenoceptor crystal structures, including antagonist, inverse agonist, and partial/full agonist-bound structures, allowed us to explore the possibilities and limitations of structure-based prediction of GPCR ligand function. We used all unique protein-ligand interaction fingerprints (IFPs) derived from all ligand-bound β-adrenergic crystal structure monomers to post-process the docking poses of known β1R/β2R partial/full agonists, antagonists/inverse agonists, and physicochemically similar decoys in each of the β1R/β2R structures. The systematic analysis of these 1920 unique IFP-structure combinations offered new insights into the relative impact of protein conformation and IFP scoring on selective virtual screening (VS) for ligands with a specific functional effect. Our studies show that ligands with the same function can be efficiently classified on the basis of their protein-ligand interaction profile. Small differences between the receptor conformation (used for docking) and reference IFP (used for scoring of the docking poses) determine, however, the enrichment of specific ligand types in VS hit lists. Interestingly, the selective enrichment of partial/full agonists can be achieved by using agonist IFPs to post-process docking poses in agonist-bound as well as antagonist-bound structures. We have identified optimal structure-IFP combinations for the identification and discrimination of antagonists/inverse agonist and partial/full agonists, and defined a predicted IFP for the small full agonist norepinephrine that gave the highest retrieval rate of agonists over antagonists for all structures (with an enrichment factor of 46 for agonists and 8 for antagonists on average at a 1% false-positive rate). This β-adrenoceptor case study provides new insights into the opportunities for selective structure-based discovery of GPCR ligands with a desired function and emphasizes the importance of IFPs in scoring docking poses.

Stroke is a multi-factorial disease caused by a combination of genetic and environmental factors. The purpose of this case control study was to determine the relationship of beta-1 adrenergic receptor polymorphism with ischemic stroke in North Indian population. In this study, 224 patients and 224 age- and sex-matched controls were recruited from the outpatient department and neurology ward of All India Institute of Medical Sciences, New Delhi. Genotyping was performed by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. PCR results were confirmed by DNA sequencing. Frequency distributions of genotypes and alleles were compared between cases and controls using logistic regression. Mean age of cases and controls was 53.9 ± 13.4 and 53.6 ± 12.9 years respectively. Multivariate logistic regression analysis showed an independent association between Ser49Gly polymorphism and ischemic stroke under a dominant model of inheritance (OR, 2.5; 95% CI, 1.2 to 5) and large vessel disease (LVD) under a recessive model of inheritance (OR, 6.5; 95% CI, 1.7 to 23; P=0.005). Independent association of Arg389Gly polymorphism with small vessel disease (SVD) (OR, 7.09; 95% CI, 1.9 to 25; P=0.003) under recessive model of inheritance. The findings of the present study Ser49Gly polymorphism of the ADRB1 gene confer higher risk of ischemic stroke in a North Indian population and especially in patients with LVD. Our findings also show that Arg389Gly polymorphism of ADRB1 confers higher risk of SVD in North Indian population.

BACKGROUND: Stroke is a multifactorial, polygenic disorder, influenced by both environmental and genetic factors.
OBJECTIVE: The purpose of this study was to determine the association of beta-1 and beta-2 adrenergic receptor (AR) polymorphisms with intracerebral hemorrhagic stroke (ICH) in a North Indian population.
METHODS: One hundred and six patients with intracerebral hemorrhage (ICH) and 106 age- and sex- matched controls were recruited. Genotyping was performed by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. RFLP results of three samples of each genotype were confirmed by DNA sequencing.
RESULTS: Mean age of cases and controls were 53.47 ± 14 and 52.92 ± 13.4, respectively. Significant association between Ser49Gly polymorphism of beta-1 AR and ICH in patients who had onset of disease at a later stage of life (>50 years) under a dominant model of inheritance (OR, 3.6; 95% 1.4 to 9.7) was observed. Under the dominant model of inheritance, Gln27Glu polymorphism of beta-2 AR was associated with risk of ICH (OR, 3.2; 95% CI, 1.7 to 5.8) and significant association persisted even after adjustment for demographic and other risk factor variables (OR, 2.9; 95% CI, 1.04 to 8; P = 0.04). Age-stratified analysis showed an independent significant association of Gln27Glu polymorphism of beta-2 AR with risk of ICH in patients those had onset of disease at young age (<50 years) under a dominant model of inheritance (OR, 3.5; 95% CI, 1.1 to 11).
CONCLUSIONS: The present study provides the first preliminary evidence that Gln27Glu polymorphism of beta-2 AR may contribute modest effect in increase in risk of ICH in North Indian Population. Large prospective studies with large sample size are required to confirm these findings.

BACKGROUND: Adrenergic activation has a central role in the development of HF. The function of the beta1- and the alpha2C-adrenergic receptors is influenced by gene polymorphisms: the beta1Arg389 variant is associated with increased beta1-receptor sensitivity and the alpha2C-receptor Del322-325 variant is associated with decreased alpha2C receptor function and increased norepinephrine release. We hypothesised that these polymorphisms could influence the prevalence of heart failure.
METHODS: The role of the beta1- and alpha2C-adrenergic receptor gene polymorphisms as risk factors for heart failure (HF) was assessed in an Italian white Caucasian population using a case-control study design. Genomic DNA was analysed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RLFP).
RESULTS: We compared 260 Caucasian patients with HF and 230 normal subjects. The beta1Arg389 allele was frequent both in the patients with HF (69%) and in the normal subjects (73%). The alpha2CDel322-325 variant was rare in both groups (9% and 8%, respectively). Patients homozygotes for either the beta1Arg389 or the alpha(2C)Del322-325 alleles had no increased risk of HF (odds ratio [OR], 0.8; 95%CI: 0.5-1.2 and OR, 0.8; 95% CI: 0.4-1.8, respectively). Patients homozygotes for both the beta1Arg389 and the alpha(2C)Del322-325 alleles had no increased risk of HF as well (OR: 0.6; 95% CI: 0.2-2.1).
CONCLUSIONS: Beta1-ARs and alpha2C-ARs polymorphisms are not associated with an increased risk of HF in an Italian white Caucasian population.

BACKGROUND: We hypothesised that the polymorphisms of the genes encoding for beta1- and the beta2-adrenoceptors may have a role in the pathogenesis of heart failure (HF). We therefore compared the polymorphisms of the beta1-adrenoceptor gene (Arg389Gly), the beta2-adrenoceptor gene (Arg16Gly, Gln27Glu) and their combinations in patients with HF and normal subjects living in the same area.
RESULTS: A total of 256 cases with HF (left ventricular ejection fraction < or = 40%) and 230 normal subjects were enrolled. The beta1- and beta2-adrenoceptor gene polymorphisms were assessed by PCR, followed by restriction enzyme digestion. No differences were observed in the distribution of any of the three genotypes studied in patients with HF and normal subjects. An analysis of the genotype combinations showed a non-significant increase in the risk of HF associated with the Arg389Gly16Gln27 (odds ratio = 1.4; 95%CI 0.5-3.6) and Arg389Gly16 Glu27 (odds ratio = 1.2; 95%CI, 0.5-2.8) homozygous allele combinations.
CONCLUSIONS: None of the three most common polymorphisms of beta-adrenoreceptors are associated with an increased risk of HF.