S100A2 in cancerogenesis: a friend or a foe?

Owing to the exceptional intracellular distribution and the heterogeneous expression pattern during transformation and metastasis in various tumors, the EF-hand calcium-binding protein S100A2 attracts increasing attention. Unlike the majority of S100 proteins, S100A2 expression is downregulated in many cancers and the loss in nuclear expression has been associated with poor prognosis. On the other hand, S100A2 is upregulated in some cancers. This mini review highlights the general characteristics of S100A2 and discusses recent findings on its putative functional implication as a suppressor or promoter in cancerogenesis.     

Growth and analysis of crystal forms of toxic shock syndrome toxin 1

Native toxic shock syndrom toxin 1 (TSST-1) purified from Staphylococcus aurius has been crystallized in four different forms. The highest resolution data (2.05 Å) was collected from orthorhombic crystals belonging to the space group C222₁. The unit cell dimension are a = 108.7 Å, b = 177.5 Å, c = 97.6 Å. Rotation function analysis of this from indicates that there is trimer of toxin molecules in the asymmetric unit with a local 3-fold axis parallel to the crystallographic c axis. Crystals of a double mutant of TSST-1 have been grown which has a single molecule in the asymmetric unit and diffract to 1.9 Å. The space group is P2₁ with unit cell parameters of a = 44.4 Å, b = 34.0 Å, c = 55.2 Å, β = 93.0°. © 1993 Wiley-Liss, Inc.     

Population genetic structure of a California endemic branchiopod,Branchinecta sandiegonensis

Branchinecta sandiegonensis (Crustacea: Anostraca) is a narrow range endemic fairy shrimp discontinuously distributed in ephemeral pools on coastal mesas in San Diego County, USA. Ten populations across the range of the species were subjected to allozyme analysis for eleven loci. The species exhibits low variability (P₉₅ =9.1–45.5) and one third of the loci tested did not conform to Hardy-Weinberg equilibrium expectations. The species also exhibited a high degree of genetic differentiation between populations. F _ST values (fixation index) for most pairs of populations were above 0.25 (0.036–0.889).Low genetic variability and high genetic structure may result from low gene flow and founder effects due to habitat fragmentation and the lack of potential vectors for cyst dispersal. The unpredictable rainfall of the region also creates potential for variable population sizes which could affect structure and variability. This revised version was published online in August 2006 with corrections to the Cover Date.     

Sustained effects of biofeedback-assisted relaxation therapy in essential hypertension

The usefulness of biofeedback-assisted relaxation as an adjunct or substitute for pharmacotherapy in essential hypertension can be enhanced if the effects are shown to persist after formal treatment has ended. Patients with essential hypertension successfully treated with biofeedback-assisted relaxation were recalled for follow-up yearly after the termination of treatment. Twenty-six of 40 patients met the BP criterion for success. At one-, two-, and three-year follow-up, 31%, 38%, and 27% of the successful completers continued to meet the criterion for success. The pretreatment-posttreatment decreases in BP were accompanied by decreases in forehead muscle tension and urinary cortisol. Forehead muscle tension, urinary cortisol, and anxiety levels were significantly lower than pretreatment one year after the end of treatment. Self-report data were used to assess continued relaxation practice. No relationship was found between practice and any other dependent measure. It appears that some patients trained in biofeedback-assisted relaxation can maintain lowered blood pressure, muscle tension, anxiety, and cortisol levels over the long term; however, the role of relaxation practice in maintaining these lowered levels remains unclear.     

Capacitance,short-circuit current and osmotic water flow across different regions of the isolated toad skin

Summary The amphibian antidiuretic hormone, arginine vasotocin, stimulated osmotic water flow across isolated skin from the pelvic but not the pectoral skin of the toad, Bufo woodhouseii. Changes in the apical membrane capacitance were not observed for either region of the skin following treatment with arginine vasotocin when there was an osmotic gradient across the tissue. In the absence of an osmotic pressure gradient, the apical membrane capacitance of the pelvic skin increased from 2.8±0.5 to 3.3±0.6 F · cm^-2 after treatment with 5 · 10^-8 M arginine vasotocin. Under these conditions, apical membrane capacitance of the pectoral skin was 1.8±0.1 F · cm^-2 and did not change significantly after arginine vasotocin treatment. The amiloride-sensitive short-circuit current across the pelvic skin was stimulated by arginine vasotocin as was the density of channels in the apical membrane as determined by fluctuation analysis. Values for channel density in the pelvic skin also correlated with apical membrane capacitance and increased from 90 to 273 channels per m² of estimated membrane area following arginine vasotocin treatment. In the pectoral skin the stimulation of short-circuit current following arginine vasotocin treatment was small and an increase in channel density could not be demonstrated. The current through single Na⁺ channels in both regions of the skin did not different either before or after arginine vasotocin treatment.Abbreviations A amiloride - ADH antidiuretic hormone - AVT arginine vasotocin - C capacitance - C _a capacitance of apical membrane - f _c corner frequency - i single-channel current - osmotic water flow - IMP intramembrane particles - I _sc short-circuit current - amiloride-sensitive short-circuit current - M channel density - P _o probability of a channel being open - R channel receptor - R _a apical resistance - R _p paracellular resistance     

Effect of pseudophosphorylation and cross-linking by lipid peroxidation and advanced glycation end product precursors on tau aggregation and filament formation

Accumulation of hyperphosphorylated Tau protein as paired helical filaments in pyramidal neurons is a major hallmark of Alzheimer disease. Besides hyperphosphorylation, other modifications of the Tau protein, such as cross-linking, are likely to contribute to the characteristic features of paired helical filaments, including their insolubility and resistance against proteolytic degradation. In this study, we have investigated whether the four reactive carbonyl compounds acrolein, malondialdehyde, glyoxal, and methylglyoxal accelerate the formation of Tau oligomers, thioflavin T-positive aggregates, and fibrils using wild-type and seven pseudophosphorylated mutant Tau proteins. Acrolein and methylglyoxal were the most reactive compounds followed by glyoxal and malondialdehyde in terms of formation of Tau dimers and higher molecular weight oligomers. Furthermore, acrolein and methylglyoxal induced the formation of thioflavin T-fluorescent aggregates in a triple pseudophosphorylation-mimicking mutant to a slightly higher degree than wild-type Tau. Analysis of the Tau aggregates by electron microscopy study showed that formation of fibrils using wild-type Tau and several Tau mutants could be observed with acrolein and methylglyoxal but not with glyoxal and malondialdehyde. Our results suggest that reactive carbonyl compounds, particularly methylglyoxal and acrolein, could accelerate tangle formation in vivo and that this process could be slightly accelerated, at least in the case of methylglyoxal and acrolein, by hyperphosphorylation. Interference with the formation or the reaction of these reactive carbonyl compounds could be a promising way of inhibiting tangle formation and neuronal dysfunction in Alzheimer disease and other tauopathies.