Formation and characterization of stable human serum albumin-tris-malonic acid [C60]fullerene complex

The preparation and characterization of the stable human serum albumin (HSA)-C3 isomer of tris-malonic acid [C60]fullerene complex is reported. Other than the anti-fullerene antibody, a stable protein-fullerene complex with a native protein has never been observed. This study may provide valuable answers to the growing concern regarding the effects of carbonaceous nanomaterials on human health on one hand and, on the other, may lead to the development of novel antioxidant therapeutic agents, radiopharmaceuticals, and components for bioelectronic devices.     

Subcellular localization of VDAC in mitochondria and ER in the cerebellum

The voltage-dependent anion channel (VDAC) provides passage for adenine nucleotides, Ca2+ and other metabolites into and from mitochondria. Here, the intracellular localization and oligomeric organization of VDAC in brain mitochondria and ER are demonstrated. Immunohistochemical staining of VDAC in rat cerebellum showed high labeling of the Purkinje neurons. Immunogold labeling and EM analysis of the cerebellar molecular layer showed specific VDAC immunostaining of the mitochondrial outer membrane, highly enhanced in contact sites between mitochondria or between mitochondria and associated ER. Purified ER membranes contain VDAC, but not other mitochondrial proteins. Chemical cross-linking of isolated mitochondria, ER or purified VDAC demonstrated the existence of VDAC in oligomeric form. Based on the enrichment of VDAC in the junctional face of closely associated mitochondrial and ER membranes and the existence of VDAC oligomers, we propose an involvement of VDAC in specialized intermembrane communication between mitochondria or between ER and mitochondria, serving to complement the tight structural and functional coupling observed between these organelles.     

Delineation of Cohen syndrome following a large-scale genotype-phenotype screen

Cohen syndrome is an autosomal recessive condition associated with developmental delay, facial dysmorphism, pigmentary retinopathy, and neutropenia. The pleiotropic phenotype, combined with insufficient clinical data, often leads to an erroneous diagnosis and has led to confusion in the literature. Here, we report the results of a comprehensive genotype-phenotype study on the largest cohort of patients with Cohen syndrome assembled to date. We found 22 different COH1 mutations, of which 19 are novel, in probands identified by our diagnostic criteria. In addition, we identified another three novel mutations in patients with incomplete clinical data. By contrast, no COH1 mutations were found in patients with a provisional diagnosis of Cohen syndrome who did not fulfill the diagnostic criteria ("Cohen-like" syndrome). This study provides a molecular confirmation of the clinical phenotype associated with Cohen syndrome and provides a basis for laboratory screening that will be valuable in its diagnosis.     

Impact of acute hypoxic pulmonary hypertension on LV diastolic function in healthy mountaineers at high altitude

In pulmonary hypertension right ventricular pressure overload leads to abnormal left ventricular (LV) diastolic function. Acute high-altitude exposure is associated with hypoxia-induced elevation of pulmonary artery pressure particularly in the setting of high-altitude pulmonary edema. Tissue Doppler imaging (TDI) allows assessment of LV diastolic function by direct measurements of myocardial velocities independently of cardiac preload. We hypothesized that in healthy mountaineers, hypoxia-induced pulmonary artery hypertension at high altitude is quantitatively related to LV diastolic function as assessed by conventional and TDI Doppler methods. Forty-one healthy subjects (30 men and 11 women; mean age 41 +/- 12 yr) underwent transthoracic echocardiography at low altitude (550 m) and after a rapid ascent to high altitude (4,559 m). Measurements included the right ventricular to right atrial pressure gradient (DeltaP(RV-RA)), transmitral early (E) and late (A) diastolic flow velocities and mitral annular early (E(m)) and late (A(m)) diastolic velocities obtained by TDI at four locations: septal, inferior, lateral, and anterior. At a high altitude, DeltaP(RV-RA) increased from 16 +/- 7 to 44 +/- 15 mmHg (P < 0.0001), whereas the transmitral E-to-A ratio (E/A ratio) was significantly lower (1.11 +/- 0.27 vs. 1.41 +/- 0.35; P < 0.0001) due to a significant increase of A from 52 +/- 15 to 65 +/- 16 cm/s (P = 0.0001). DeltaP(RV-RA) and transmitral E/A ratio were inversely correlated (r(2) = 0.16; P = 0.0002) for the whole spectrum of measured values (low and high altitude). Diastolic mitral annular motion interrogation showed similar findings for spatially averaged (four locations) as well as for the inferior and septal locations: A(m) increased from low to high altitude (all P < 0.01); consequently, E(m)/A(m) ratio was lower at high versus low altitude (all P < 0.01). These intraindividual changes were reflected interindividually by an inverse correlation between DeltaP(RV-RA) and E(m)/A(m) (all P < 0.006) and a positive association between DeltaP(RV-RA) and A(m) (all P < 0.0009). In conclusion, high-altitude exposure led to a two- to threefold increase in pulmonary artery pressure in healthy mountaineers. This acute increase in pulmonary artery pressure led to a change in LV diastolic function that was directly correlated with the severity of pulmonary hypertension. However, in contrast to patients suffering from some form of cardiopulmonary disease and pulmonary hypertension, in these healthy subjects, overt LV diastolic dysfunction was not observed because it was prevented by augmented atrial contraction. We propose the new concept of compensated diastolic (dys)function.     

Differential regulation of polygalacturonase and pectin methylesterase gene expression during and after heat stress in ripening tomato (Lycopersicon esculentum Mill.) fruits

The effects of extended heat stress on polygalacturonase (PG; EC 3.2.1.15) and pectin methylesterase (PME; EC 3.1.1.11) gene expression at mRNA, protein and activity levels in ripening tomato fruits were investigated. Steady state levels of PG mRNA declined at temperatures of 27°C and above, and a marked reduction in PG protein and activity was observed at temperatures of 32°C and above. Exogenous ethylene treatment did not reverse heat stress-induced inhibition of PG gene expression. Transfer of heat-stressed fruits to 20°C partly restored PG mRNA accumulation, but the rate of PG mRNA accumulation declined exponentially with duration of heat stress. Heat stress-induced inhibition of PME mRNA accumulation was recoverable even after 14 days of heat stress. In fruits held at 34°C, both PG and PME protein and activity continued to accumulate for about 4 days, but thereafter PG protein and activity declined while little change was observed in PME protein and activity. In spite of increases in mRNA levels of both PG and PME during the recovery of heat-stressed fruit at 20°C, levels of PG protein and activity declined in fruits heat-stressed for four or more days while PME protein and activity levels remained unchanged. Collectively, these data suggest that PG gene expression is being gradually and irreversibly shut off during heat stress, while PME gene expression is much less sensitive to heat stress.     

Tropolone as a substrate for horseradish peroxidase

Tropolone (2,4,6-cycloheptatrien-1-one), in the presence of hydrogen peroxide but not in its absence, can serve as a donor for the horseradish peroxidase catalysed reaction. The product formed is yellow and is characterized by a new peak at 418 nm. The relationship between the rate of oxidation of tropolone (ΔA at 418 nm/min) and various concentrations of horseradish peroxidase, tropolone and hydrogen peroxide is described. The yellow product obtained by the oxidation of tropolone by horseradish peroxidase in the presence of hydrogen peroxide was purified by chromatography on Sephadex G-10 and its spectral properties at different pHs are presented. The M, of the yellow product was estimated to be ca 500, suggesting that tropolone, in the presence of horseradish peroxidase and hydrogen peroxide is converted to a tetratropolone.