Association of Superoxide dismutases (SOD1 and SOD2) and Glutathione peroxidase 1 (GPx1) gene polymorphisms with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a metabolic disorder resulting from oxidative stress (OS), the root cause of insulin resistance, β-cell dysfunction, and impaired glucose tolerance. Antioxidant enzymes play key roles in cellular defense and can be used as important biomarkers for T2DM. The present study was undertaken to evaluate three genetic polymorphisms viz. SOD1 + 35A/C, SOD2 + 47C/T, and GPx + 599C/T in 207 T2DM cases and 210 healthy controls from North India. DNA was extracted from blood samples and genotyping was done by PCR-RFLP. Genotypic/allelic frequencies and haplotype/gene-gene interaction analysis were performed using SPSS (version 15.0) and SHEsis (v. online). Except age, all other biochemical parameters showed highly significant association in T2DM cases (P < 0.001). In North Indian population, SOD1 + 35A/C variant was monomorphic. Genotype/allele frequencies of SOD2 + 47C/T polymorphism and carriage rate of 'C' allele showed significant association (p < 0.05, < 0.001; OR 2.434). Genotype/allele frequencies of GPx1 + 599C/T and carriage rate showed no association although the odds ratio of GPx1 'C' allele indicated a 1.362 times higher risk of T2DM. SOD2 'CT' and GPx1 'CC' genotypes showed maximum association with biochemical parameters. Haplotype/gene-gene interaction analysis in controls and cases showed that SOD2 + 47C/T and GPx1 + 599C/T were in linkage disequilibrium (D: 0.168; r(2): 0.10) and individuals with this combination had a 1.273 times higher risk [OR; CI (95%)] of developing T2DM. Thus, we conclude that it is essential to assess the combinatorial association of gene variants with T2DM in order to identify risk haplotypes in a population.

Crystal structure of peptidyl-tRNA hydrolase from a Gram-positive bacterium, Streptococcus pyogenes at 2.19 Å resolution shows the closed structure of the substrate-binding cleft

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Structure of peptidyl-tRNA hydrolase (Pth) from Streptococcus pyogenes.

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First structure of Pth from a Gram-positive bacterium.

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Conformations of the lid and gate loops are different from those observed in other Pth enzymes.

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The substrate-binding channel is closed at both sites of the lid and gate loops.

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In Pth structures from other species, the channel is fully open at the lid loop.

Peptidyl-tRNA hydrolase (Pth) catalyses the release of tRNA and peptide components from peptidyl-tRNA molecules. Pth from a Gram-positive bacterium Streptococcus pyogenes (SpPth) was cloned, expressed, purified and crystallised. Three-dimensional structure of SpPth was determined by X-ray crystallography at 2.19 Å resolution. Structure determination showed that the asymmetric unit of the unit cell contained two crystallographically independent molecules, designated A and B. The superimposition of C^α traces of molecules A and B showed an r.m.s. shift of 0.4 Å, indicating that the structures of two crystallographically independent molecules were identical. The polypeptide chain of SpPth adopted an overall α/β conformation. The substrate-binding cleft in SpPth is formed with three loops: the gate loop, Ile91–Leu102; the base loop, Gly108–Gly115; and the lid loop, Gly136–Gly150. Unlike in the structures of Pth from Gram-negative bacteria, the entry to the cleft in the structure of SpPth appeared to be virtually closed. However, the conformations of the active site residues were found to be similar.

Long-term quality of life after living kidney donation

BACKGROUND

The supply of deceased donor kidneys available for transplantation is not sufficient to meet the demand. Despite a low rate of complications for donors and superior outcomes for recipients, living kidney donation (LKD) is on the decline for reasons that remain unclear.

METHODS

We performed a retrospective review and analysis of living kidney donors (LDs) who underwent donor nephrectomy between January 1, 2000 and December 31, 2010. Candidates who were excluded from LKD were identified as control subjects (CSs). LDs and CSs were invited to voluntarily undergo a quality of life assessment using Short Form 12 v1.0 Questionnaire (SF-12) and an addendum questionnaire (AQ). The SF-12 and AQ were administered by telephone. Statistical analysis of the results was performed to obtain the SF-12 physical component score (PCS), SF-12 mental component score (MCS), and the AQ score. PCS and MCS for the general population were obtained from the 1998 National Survey of Functional Health Status.

RESULTS

During the study period, 83 LDs and 116 CSs were interviewed. LDs were noted to have higher PCS (54.1 vs 49.6) and MCS (55.7 vs 49.4) compared with the general population. Ninety-nine percent of LDs believed that their quality of life did not decrease after LKD; 21.7% reported experiencing complications. Half of the LDs (48%) reported missing 1 day of work for evaluation; 71% of LDs reported missing at least 4 weeks of work after LKD. Nearly all LDs (99%) would undergo donation again. Fifty-two percent of LDs reported adhering to the recommended 2-year follow-up schedule with the transplantation team; 87% of LDs reported seeing their primary care physician.

CONCLUSION

LDs are physically and mentally healthier after LKD compared to the general population. Most donors miss at least 1 month of work for LKD and undergo some form of post-donation monitoring. Despite this commitment, LKD is a very satisfying experience.

Occurrence of complications in newly diagnosed type 2 diabetes patients: a hospital based study

Type 2 diabetes is characterised by a long asymptomatic period of hyperglycaemia and many individuals with type 2 diabetes have complications even at the time of diagnosis. The purpose of present study was to study and compare the prevalence of complications at the time of diagnosis of type 2 diabetes in newly diagnosed asymptomatic and symptomatic patients. One hundred and five consecutive newly diagnosed cases of type 2 diabetes were selected for study based on fasting blood glucose level > or = 126 mg/dl. Individuals who were known diabetic, individuals presenting with acute complications were excluded from study. The prevalence rates of various complications in newly diagnosed diabetic patients were studied in both asymptomatic and symptomatic subjects and results were analysed statistically using test of proportion and Chi-square test. There were 40.95% of newly diagnosed diabetes patients who were asymptomatic. There was no significant difference between those having symptoms of diabetes and those without symptoms of diabetes with regard to age, sex, weight and hypertension. Occurrence of both microvascular and macrovascular complications were not different in the two groups studied. We also observed a very high prevalence of microvascular (32.55%) complications in asymptomatic newly diagnosed type 2 diabetes patients. Since 35.20% of cases in this study were below 50 years and various complications develop 10-20 years after onset of disease, this study suggests that screening for diabetes should commence at the age of 40 years in general population.

Safety of the pipeline embolization device in treatment of posterior circulation aneurysms

BACKGROUND AND PURPOSE

The published results of treating internal carotid artery aneurysms with the PED do not necessarily apply to its use in the posterior circulation because disabling brain stem infarcts can be caused by occlusion of a single perforator. In this multicenter study, we assessed the safety of PED placement in the posterior circulation.

MATERIALS AND METHODS

A prospective case registry was maintained of all posterior circulation aneurysms treated with PEDs at 3 Australian neurointerventional centers during a 27-month period. The objective was to assess the complications and aneurysm occlusion rates associated with posterior circulation PEDs.

RESULTS

Thirty-two posterior circulation aneurysms were treated in 32 patients. No deaths or poor neurologic outcomes occurred. Perforator territory infarctions occurred in 3 (14%) of the 21 patients with basilar artery aneurysms, and in all 3, a single PED was used. Two asymptomatic intracranial hematomas were recorded. No aneurysm rupture or PED thrombosis was encountered. The overall rate of permanent neurologic complications was 9.4% (3/32); all 3 patients had very mild residual symptoms and a good clinical outcome. Aneurysm occlusion was demonstrated in 85% of patients with >6 months of follow-up and 96% of patients with >1 year of follow-up.

CONCLUSIONS

The PED is effective in the treatment of posterior circulation aneurysms that are otherwise difficult or impossible to treat with standard endovascular or surgical techniques, and its safety is similar to that of stent-assisted coiling techniques. A higher clinical perforator infarction rate may be associated with basilar artery PEDs relative to the internal carotid artery.

A risk-prediction model for in-hospital mortality after heart transplantation in US children

We sought to develop and validate a quantitative risk-prediction model for predicting the risk of posttransplant in-hospital mortality in pediatric heart transplantation (HT). Children <18 years of age who underwent primary HT in the United States during 1999-2008 (n = 2707) were identified using Organ Procurement and Transplant Network data. A risk-prediction model was developed using two-thirds of the cohort (random sample), internally validated in the remaining one-third, and independently validated in a cohort of 338 children transplanted during 2009-2010. The best predictive model had four categorical variables: hemodynamic support (ECMO, ventilator support, VAD support vs. medical therapy), cardiac diagnosis (repaired congenital heart disease [CHD], unrepaired CHD vs. cardiomyopathy), renal dysfunction (severe, mild-moderate vs. normal) and total bilirubin (≥ 2.0, 0.6 to <2.0 vs. <0.6 mg/dL). The C-statistic (0.78) and the Hosmer-Lemeshow goodness-of-fit (p = 0.89) in the model-development cohort were replicated in the internal validation and independent validation cohorts (C-statistic 0.75, 0.81 and the Hosmer-Lemeshow goodness-of-fit p = 0.49, 0.53, respectively) suggesting acceptable prediction for posttransplant in-hospital mortality. We conclude that this risk-prediction model using four factors at the time of transplant has good prediction characteristics for posttransplant in-hospital mortality in children and may be useful to guide decision-making around patient listing for transplant and timing of mechanical support.

Crystal structure of peptidyl-tRNA hydrolase from mycobacterium smegmatis reveals novel features related to enzyme dynamics

Peptidyl-tRNA hydrolase from Mycobacterium smegmatis is a single domain 21 kDa protein involved in the hydrolysis of prematurely produced peptidyl-tRNAs to ensure the viability of cells in bacteria, thus making it a potentially important drug target. In order to aid the development of potent drugs for controlling bacterial infections, the three-dimensional structure of peptidyl-tRNA hydrolase from Mycobacterium smegmatis has been determined. The protein adopts a compact α/β globular fold with a twisted β-sheet surrounded by α-helices. The functionally important C-terminal stretch has been unambiguously modeled for the first time in the unliganded structure of peptidyl-tRNA hydrolase. The segment, Gly138 - Val150 is mobile because it lacks significant interactions with the rest of the protein molecule. This conformational flexibility is reflected through different values of distances between a reference atom Ala147 C(α) of the segment Gly138 - Val150 to Gly114 C(α) from another segment from opposite side of the substrate binding channel in Mycobacterium smegmatis (7.8 Ǻ), Mycobacterium tuberculosis (9.5 Ǻ) and Escherichia coli (11.8 Ǻ). Similarly, the conformation of loop Gly109 - Gly117 with respect to another loop Asp95 - Asp100 also shows variability of the substrate binding cleft as the distance between Asp98 O(δ2) to Gly113 C(α) in Mycobacterium smegmatis is 4.5 Ǻ while the corresponding distances in Mycobacterium tuberculosis and Escherichia coli are 3.1 Ǻ and 6.7 Ǻ respectively. The hydrogen bonded interactions between Asn116, His22 and Asp95 indicate a stereochemically favorable arrangement of these residues for catalytic action.

Trends in wait-list mortality in children listed for heart transplantation in the United States: era effect across racial/ethnic groups

We sought to evaluate trends in overall and race-specific pediatric heart transplant (HT) wait-list mortality in the United States (US) during the last 20 years. We identified all children <18 years old listed for primary HT in the US during 1989-2009 (N = 8096, 62% White, 19% Black, 13% Hispanic and 6% Other) using the Organ Procurement and Transplant Network database. Wait-list mortality was assessed in four successive eras (1989-1994, 1995-1999, 2000-2004 and 2005-2009). Overall wait-list mortality declined in successive eras (26%, 23%, 18% and 13%, respectively). The decline across eras remained significant in adjusted analysis (hazard ratio [HR] 0.70 in successive eras, 95% confidence interval [CI], 0.67-0.74) and was 67% lower for children listed during 2005-2009 versus those listed during 1989-1994 (HR 0.33; CI, 0.28-0.39). In models stratified by race, wait-list mortality decreased in all racial groups in successive eras. In models stratified by era, minority children were not at higher risk of wait-list mortality in the most recent era. We conclude that the risk of wait-list mortality among US children listed for HT has decreased by two-thirds during the last 20 years. Racial gaps in wait-list mortality present variably in the past are not present in the current era.

Endovascular treatment using predominantly stent-assisted coil embolization and antiplatelet and anticoagulation management of ruptured blood blister-like aneurysms

BACKGROUND AND PURPOSE

BBA is a rare type of intracranial aneurysm that is difficult to treat both surgically and endovascularly and is often associated with a high degree of morbidity/mortality. The aim of this study was to present clinical and angiographic results, as well as antiplatelet/anticoagulation regimens, of endovascular BBA treatment by using predominantly stent-assisted coil embolization.

MATERIALS AND METHODS

Thirteen patients (men/women, 6/7; mean age, 49.3 years) with ruptured BBAs were included from 2 different institutions. Angiographic findings, treatment strategies, anticoagulation/antiplatelet protocols, and clinical (mRS) and angiographic outcome were retrospectively analyzed.

RESULTS

Eleven BBAs were located in the supraclinoid ICA, and 2 on the basilar artery trunk. Nine of 13 were ≤3 mm in the largest diameter, and 8/13 showed early growth before treatment. Primary stent-assisted coiling was performed in 11/13 patients, double stents and PAO in 1 patient, each. Early complementary treatment was required in 3 patients, including PAO in 2. In stent-placement procedures, altered periprocedural antiplatelet (11/12) and postprocedural heparin (6/12) protocols were used without evidence of thromboembolic events. Two patients had early rehemorrhage, including 1 major fatal SAH. Twelve of 13 BBAs showed complete or progressive occlusion at late angiographic follow-up. Clinical midterm outcome was good (mRS scores, 0-2) in 12/13 patients.

CONCLUSIONS

Stent-assisted coiling of ruptured BBAs is technically challenging but can be done with good midterm results. Reduced periprocedural and postprocedural antiplatelet/anticoagulation protocols may be used with a low reasonable risk of thromboembolic complications. However, regrowth/rerupture remains a problem underlining the importance of early angiographic follow-up and re-treatment, including PAO if necessary.

Association of race and socioeconomic position with outcomes in pediatric heart transplant recipients

We assessed the association of socioeconomic (SE) position with graft loss in a multicenter cohort of pediatric heart transplant (HT) recipients. We extracted six SE variables from the US Census 2000 database for the neighborhood of residence of 490 children who underwent their primary HT at participating transplant centers. A composite SE score was derived for each child and four groups (quartiles) compared for graft loss (death or retransplant). Graft loss occurred in 152 children (122 deaths, 30 retransplant). In adjusted analysis, graft loss during the first posttransplant year had a borderline association with the highest SE quartile (HR 1.94, p = 0.05) but not with race. Among 1-year survivors, both black race (HR 1.81, p = 0.02) and the lowest SE quartile (HR 1.77, p = 0.01) predicted subsequent graft loss in adjusted analysis. Among subgroups, the lowest SE quartile was associated with graft loss in white but not in black children. Thus, we found a complex relationship between SE position and graft loss in pediatric HT recipients. The finding of increased risk in the highest SE quartile children during the first year requires further confirmation. Black children and low SE position white children are at increased risk of graft loss after the first year.

Clinical use of sildenafil in pulmonary artery hypertension

Severe pulmonary hypertension is a debilitating disease with short life expectancy that often affects young people. It is usually idiopathic pulmonary artery hypertension and is characterized by progressive elevation of pulmonary artery pressure and vascular resistance, right ventricular failure and death with a limited median survival time. There is an imbalance in vasoconstrictive and vasodilatory substances. The phosphodiesterase-5 inhibitor sildenafil, a pulmonary and penile vasodilator initially approved for erectile dysfunction, is found to be efficacious in severe pulmonary artery hypertension. There are limited treatment options for the management of pulmonary artery hypertension in developing countries and sildenafil is a reasonable treatment option. This article reviews the relevant clinical data in pulmonary hypertension and the role of sildenafil in its management.

Racial and ethnic differences in mortality in children awaiting heart transplant in the United States

Racial differences in outcomes are well known in children after heart transplant (HT) but not in children awaiting HT. We assessed racial and ethnic differences in wait-list mortality in children <18 years old listed for primary HT in the United States during 1999-2006 using multivariable Cox models. Of 3299 listed children, 58% were listed as white, 20% as black, 16% as Hispanic, 3% as Asian and 3% were defined as 'Other'. Mortality on the wait-list was 14%, 19%, 21%, 17% and 27% for white, black, Hispanic, Asian and Other children, respectively. Black (hazard ratio [HR] 1.6, 95% confidence interval [CI] 1.3, 1.9), Hispanic (HR 1.5, CI 1.2, 1.9), Asian (HR, 2.0, CI 1.3, 3.3) and Other children (HR 2.3, CI 1.5, 3.4) were all at higher risk of wait-list death compared to white children after controlling for age, listing status, cardiac diagnosis, hemodyamic support, renal function and blood group. After adjusting additionally for medical insurance and area household income, the risk remained higher for all minorities. We conclude that minority children listed for HT have significantly higher wait-list mortality compared to white children. Socioeconomic variables appear to explain a small fraction of this increased risk.

Proteomics-based approach for identification and purification of human phosphate binding apolipoprotein from amniotic fluid

Human amniotic fluid is of both maternal and fetal origin; it protects the fetus and provides the environment for growth and development of the fetus. We used a proteomics-based approach for targeting and purifying human phosphate binding protein, a member of the DING family of proteins from amniotic fluid, using Blue Sepharose CL-6B, DEAE-Sephacel and gel filtration chromatography. The protein had earlier been reported to be serendipitously purified along with PON1 (paraoxonase 1). It was identified using electro-spray-ionization-time-of-flight mass spectrometry and was found to be human phosphate binding protein. Human phosphate binding proteins have been reported to play a role as phosphate scavengers and may have a protective function against phosphate-related disorders, such as atherosclerosis, diabetes and kidney stones.

Isolation, purification, crystallization and preliminary crystallographic studies of amaryllin, a plant pathogenesis-related protein from Amaryllis belladonna

A novel antifungal protein, amaryllin, has been isolated from the underground bulbs of Amaryllis belladonna, purified to homogeneity and crystallized. The protein was extracted using ammonium sulfate fractionation. The purified protein samples indicated a molecular weight of 15 kDa on SDS-PAGE. The protein showed antifungal activity against Aspergillus flavus and Fusarium oxysporum. The N-terminal sequence of the first 15 amino-acid residues was determined using Edman degradation and did not show significant sequence identity to any known protein. The protein was crystallized using the hanging-drop vapour-diffusion method with 30% PEG 8000 as precipitating agent. The crystals diffracted to 2.7 A resolution and belonged to the orthorhombic space group I222 or I2(1)2(1)2(1), with unit-cell parameters a = 48.6, b = 61.9, c = 79.6 A. The complete sequence and structure determination of amaryllin are in progress.

Waiting list mortality among children listed for heart transplantation in the United States

BACKGROUND

Children listed for heart transplantation face the highest waiting list mortality in solid-organ transplantation medicine. We examined waiting list mortality since the pediatric heart allocation system was revised in 1999 to determine whether the revised allocation system is prioritizing patients optimally and to identify specific high-risk populations that may benefit from emerging pediatric cardiac assist devices.

METHODS AND RESULTS

We conducted a multicenter cohort study using the US Scientific Registry of Transplant Recipients. All children <18 years of age who were listed for a heart transplant between 1999 and 2006 were included. Among 3098 children, the median age was 2 years (interquartile range 0.3 to 12 years), and median weight was 12.3 kg (interquartile range 5 to 38 kg); 1294 (42%) were nonwhite; and 1874 (60%) were listed as status 1A (of whom 30% were ventilated and 18% were on extracorporeal membrane oxygenation). Overall, 533 (17%) died, 1943 (63%) received transplants, and 252 (8%) recovered; 370 (12%) remained listed. Multivariate predictors of waiting list mortality include extracorporeal membrane oxygenation support (hazard ratio [HR] 3.1, 95% confidence interval [CI] 2.4 to 3.9), ventilator support (HR 1.9, 95% CI 1.6 to 2.4), listing status 1A (HR 2.2, 95% CI 1.7 to 2.7), congenital heart disease (HR 2.2, 95% CI 1.8 to 2.6), dialysis support (HR 1.9, 95% CI 1.2 to 3.0), and nonwhite race/ethnicity (HR 1.7, 95% CI 1.4 to 2.0).

CONCLUSIONS

US waiting list mortality for pediatric heart transplantation remains unacceptably high in the current era. Specific high-risk subgroups can be identified that may benefit from emerging pediatric cardiac assist technologies. The current pediatric heart-allocation system captures medical urgency poorly. Further research is needed to define the optimal organ-allocation system for pediatric heart transplantation.

Characterization of anisotropy in viscoelastic properties of intra-abdominal soft tissues

A portable instrumentation rig is presented for characterizing nonlinear viscoelastic anisotropic response of intra-abdominal organ-tissues. Two linearly independent in-situ experiments are performed at each indentation site on the intra-abdominal organ, by subjecting the organ to 1) normal and 2) tangential displacement stimuli using the above robotic device. For normal indentation experiments, the indenter is ramped into the tissue and held for 10 seconds before sinusoidal indentation stimuli are applied. For tangential (shear) loading, the indenter tip is rigidly glued to the soft tissue surface. Sinusoidal displacement stimuli are then applied laterally in the tangential plane and the force response is recorded. Tangential loading is repeated along orthogonal directions to measure in-plane mechanical properties. Combined analysis of both experiments leads to assessment of anisotropy. In situ experiments on fresh human cadavers are currently under way at the Albany Medical College.

Cosmic inhomogeneities and averaged cosmological dynamics

If general relativity (GR) describes the expansion of the Universe, the observed cosmic acceleration implies the existence of a "dark energy." However, while the Universe is on average homogeneous on large scales, it is inhomogeneous on smaller scales. While GR governs the dynamics of the inhomogeneous Universe, the averaged homogeneous Universe obeys modified Einstein equations. Can such modifications alone explain the acceleration? For a simple generic model with realistic initial conditions, we show the answer to be "no." Averaging effects negligibly influence the cosmological dynamics.

Crystal structure of the novel complex formed between zinc alpha2-glycoprotein (ZAG) and prolactin-inducible protein (PIP) from human seminal plasma

This is the first report on the formation of a complex between zinc alpha2-glycoprotein (ZAG) and prolactin-inducible protein (PIP). The complex was purified from human seminal plasma and crystallized using 20% polyethylene glycol 9000 and 5% hexaethylene glycol. The structure of the complex has been determined using X-ray crystallographic method and refined to an R(cryst) of 0.199 (R(free)=0.239). The structure of ZAG is broadly similar to the structure of serum ZAG. The scaffolding of PIP consists of seven beta-strands that are organized in the form of two antiparallel beta-pleated sheets, resulting in the formation of a sandwiched beta-sheet. The amino acid sequence of PIP contains one potential N-glycosylation site at Asn77, and the same is found glycosylated with four sugar residues. The structure of the complex shows that the beta-structure of PIP is ideally aligned with the beta-structure of domain alpha3 of ZAG to form a long interface between two proteins. The proximal beta-strands at the long interface are arranged in an antiparallel manner. There are 12 hydrogen bonds and three salt bridges between ZAG and PIP. At the two ends of vertical interface, two salt bridges are formed between pairs of Lys41-Asp233 and Lys68-Glu229. On the perpendicular interface involving alpha1-alpha2 domains of ZAG and a loop of PIP, another salt bridge is formed. The internal space at the corner of the L-shaped structure is filled with solvent molecules including a carbonate ion. The overall buried area in the complex is approximately 914 A(2), which is considerably higher than the 660 A(2) reported for the class I major histocompatibility complex structures.

Crystal structure of the complex of group I PLA2with a group II-specific peptide Leu-Ala-Ile-Tyr-Ser (LAIYS) at 2.6 Å resolution

Phospholipases A(2)s (PLA(2)s) are widely distributed in mammals and snake venoms. They catalyze the production of arachidonic acid from membrane phospholipids leading to the bioynthesis of pro-inflammatory eicosanoids. A peptide Leu-Ala-Ile-Tyr-Ser (LAIYS) was designed and synthesized as a specific inhibitor of PLA(2). It was shown earlier that the peptide bound to group II PLA(2) specifically and had a dissociation constant (K(d)) of 8.8 x 10(-9) M. In the present studies for the binding of LAIYS with a group I PLA(2) from Naja naja sagittifera using surface plasmon resonance the dissociation constant was found to be 4.5 x 10(-5) M which is considerably lower than the value found for the group II PLA(2). In order to determine the details of binding at the molecular level, a group I PLA(2) from the venom of Naja naja sagittifera was crystallized with peptide LAIYS. The crystal structure showed the presence of LAIYS at the substrate-binding site but has fewer interactions than those observed with group II PLA(2) from Daboia russelli pulchella. The observed difference in the binding affinity is caused primarily due to poor fitting of the peptide LAIYS in the binding site of group I PLA(2). Apparently, the location of Trp 19 in group I PLA(2) is not favourable for the binding of LAIYS. The two complexes also differ drastically in the formation of intermolecular interactions. In the present structure, the side chain of Ser (P) interacts with His 48 and Asp 49 while in the complex with group II PLA(2) it was Tyr (P) OH that formed the corresponding interactions. Tyr (P) in group I PLA(2) is the main contributor of the hydrophobic interactions whereas in the complex of LAIYS with group II PLA(2) it was the peptide segment Leu-Ala-Ile that produced the bulk of hydrophobic forces. The structures further showed that the peptide LAIYS was fully inside the substrate-binding region of the group II PLA(2) while a significant portion of the peptide LAIYS was hanging outside the surface of the group I PLA(2). The buried area in the complex with group II PLA(2) was 811 A(2) whereas, the corresponding area in group I PLA(2) was 449 A(2). This shows that the peptide LAIYS is very compatible with the substrate-binding site of group II PLA(2) and rather poorly fits into the substrate-binding site of group I PLA(2). This indicates that a highly specific ligand for one form of PLA(2) may be a poor partner for another form of enzyme.

Endothelin and its receptor interactions: role of extracellular receptor domain and length of peptide ligands

Human endothelin B receptor and its domain-truncated forms were cloned and expressed in Pichia pastoris. Ligand binding studies with expressed proteins were carried out using biotinylated endothelins. Competitive binding and liposome incorporation studies showed that the extracellular region is essential for ligand binding and that longer peptides have higher affinity.

The mistletoe lectin I--phloretamide structure reveals a new function of plant lectins

The X-ray structure at 2.7A resolution of the complex between the European mistletoe lectin I (Viscum album, ML-I) and the plant growth hormone, 3-(p-hydroxyphenyl)-propionic acid amide (phloretamide, PA) from xylem sap has revealed the binding of PA at the so far undescribed hydrophobic cavity located between the two subunits of this ribosome-inhibiting protein. No such cavity is observed in related lectins. The binding of PA is achieved through interactions with the non-conserved residues Val228A, Leu230A, Arg388B, and the C-terminal Pro510B. It is conceivable that binding of PA to ML-I is part of a defence mechanism of the parasite against the host, whereby the parasite prevents the growth hormone of the host from interfering with its own regulatory system. The specific binding of PA to ML-I indicates that heterodimeric RIPs are multifunctional proteins whose functions in the cell have not yet been fully recognized and analyzed.

Cardiac rehabilitation improves heart rate recovery following peak exercise in children with repaired congenital heart disease

We assessed heart rate (HR) recovery following peak exercise before and after a 12-week cardiac rehabilitation program in 14 children, 12.1+/-1.8 years of age, with repaired complex congenital heart disease (CHD; 11 with Fontan surgery) and impaired exercise performance. Exercise testing using bicycle ergometry was performed at baseline, after completion of the rehab program and 1.0+/-0.2 years after the baseline test. These data were compared to HR recovery in 15 controls (age, 12.7+/-2.4 years) with CHD (13 with Fontan surgery) with two serial exercise tests at an interval of 1.1+/- 0.3 years. There was no change in peak HR between the two serial tests in either group. Peak VO2 improved in the rehab group (26.3+/-9.6 ml/kg/min at baseline vs 30.9+/-9.6 ml/kg/min after rehab, p=0.01) but remained unchanged in controls on serial testing. One-minute HR recovery (in beats per minute) improved significantly following completion of the rehab program (27+/-15 at baseline vs 40+/-23 after rehab, p=0.01). Partial improvement in 1-minute HR recovery in the rehab group persisted 1 year later (1-minute HR recovery, 35+/-19; p=0.1 compared to baseline). There was no change in 1-minute HR recovery over time in the control group (37+/-16 vs 40+/-13, p = not significant). In conclusion, HR recovery following peak exercise improves in children with CHD after participation in a cardiac rehab program.

Protective role of antioxidant enzymes under high temperature stress

An experiment was conducted to study the effect of high temperature stress on the antioxidant enzyme activity in five wheat genotypes viz., PBW 343, PBW 175, HDR-77, HD 2815 and HD 2865. There was significant increase in the activity of superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT) in the late and very late planting and at all stages of plant growth, i.e., vegetative, anthesis and 15 days after anthesis (DAA), however glutathione reductase (GR) and peroxidase (POX) activity decreased under late and very late plantings compared to normal planting. In general HD 2815, HDR-77 showed relatively higher SOD, APX, GR, CAT and POX activity in the late plantings compared to PBW 343, PBW 175 and HD 2865. Significant reduction in chlorophyll content and increase in membrane injury index were observed in all genotypes with age, and also under late and very late sowings at all the stages of plant growth. However HD 2815 and HDR-77, which showed highest activity of various antioxidant enzymes under late and very late sowing also showed minimum reduction in chlorophyll content and lower membrane injury index, indicating the amelioration of high temperature stress induced oxidative stress by antioxidant enzymes. Various antioxidant enzymes showed positive correlation (r) with chlorophyll content and negative with membrane injury index at most of the stages in the five wheat genotypes.

Specific binding of non-steroidal anti-inflammatory drugs (NSAIDs) to phospholipase A2: structure of the complex formed between phospholipase A2 and diclofenac at 2.7 A resolution

Type IIA secretory phospholipase A2 (PLA2) enzymes catalyze the hydrolysis of the sn-2 ester bond of glycerophospholipids to release fatty acids and lysophospholipids. In order to elucidate the role of PLA2 in inflammatory disorders and to determine the mode of binding of non-steroidal anti-inflammatory drugs (NSAIDs) to PLA2, the detailed three-dimensional structure of a complex formed between a group IIA PLA2 from Daboia russelli pulchella and 2-[(2,6-dichlorophenyl)amino]benzeneacetic acid (diclofenac) has been determined. The preformed complex was crystallized by equilibrating the protein solution against a mixture of 0.20 M ammonium sulfate and 30% PEG 4000. The crystals belong to space group P4(3), with unit-cell parameters a = b = 53.0, c = 48.4 A. The structure was solved by the molecular-replacement method and refined to R(cryst) and R(free) factors of 0.192 and 0.211, respectively, using reflections to 2.7 A resolution. The structure showed that diclofenac occupies a very favourable position in the centre of the substrate-binding hydrophobic channel that allows a number of intermolecular interactions. The binding mode of diclofenac involved crucial interactions with important residues for substrate recognition such as Asp49, His48 and Gly30. In addition, it included three new interactions involving its Cl atoms with Phe5, Ala18 and Tyr22. It also showed an extensive network of hydrophobic interactions involving almost all of the residues of the substrate-binding hydrophobic channel. The binding affinity of diclofenac was determined using surface plasmon resonance, which gave an equilibrium constant of 4.8 +/- 0.2 x 10(-8) M.