Weight Loss Predicts Progression of Mild Cognitive Impairment to Alzheimer’s Disease

Background

Weight loss is common in people with Alzheimer’s disease (AD) and it could be a marker of impending AD in Mild Cognitive Impairment (MCI) and improve prognostic accuracy, if accelerated progression to AD would be shown.

Aims

To assess weight loss as a predictor of dementia and AD in MCI.

Methods

One hundred twenty-five subjects with MCI (age 73.8 ± 7.1 years) were followed for an average of 4 years. Two weight measurements were carried out at a minimum time interval of one year. Dementia was defined according to DSM-IV criteria and AD according to NINCDS-ADRDA criteria. Weight loss was defined as a ≥4% decrease in baseline weight.

Results

Fifty-three (42.4%) MCI progressed to dementia, which was of the AD-type in half of the cases. Weight loss was associated with a 3.4-fold increased risk of dementia (95% CI = 1.5–6.9) and a 3.2-fold increased risk of AD (95% CI = 1.4–8.3). In terms of years lived without disease, weight loss was associated to a 2.3 and 2.5 years earlier onset of dementia and AD.

Conclusions

Accelerated progression towards dementia and AD is expected when weight loss is observed in MCI patients. Weight should be closely monitored in elderly with mild cognitive impairment.     

HTLV-I protease cleavage of P19/24 substrates is not dependent on NaCl concentration

Understanding the factors that affect the activity of Human T-cell Leukemia Virus type I (HTLV-I) protease is essential for the discovery of inhibitors to be used for the treatment of HTLV-I infection, but little has been reported on the protease to date. Here we report the production of HTLV-I protease in purified yields greater than 150 mg/L, determination of its extinction coefficient, and determination of the optimum conditions for cleavage of the p19/24 substrates (DABCYL)-(GABA)-PQVL-Nph-VMH-(EDANS), (DABSYL)-(GABA)-PQVL-Nph-VMH-(EDANS), and (DABSYL)-(GABA)-PQVLPVMH-(EDANS). The highest activity was found at pH 5.2-5.3 and 37 degrees C. There was no effect on activity upon change in sodium chloride concentration from 0 to 1500 mM. The values of K(m) and k(cat) for cleavage of these substrates by the protease with and without the histidine tag were determined.     

Analysis of protein distribution in budding yeast

Flow cytometry is a fast and sensitive method that allows monitoring of different cellular parameters on large samples of a population. Protein distributons give relevant information on growth dynamics, since they are related to the age distribution and depend on the law of growth of the population and the law of protein accumulation during the cell cycle. We analyzed protein distributions to evaluate alternative growth models for the budding yeast Saccharomyces cerevisiae and to monitor the changes in population dynamics that result from environmental modifications; such an analysis could potentially give parameters useful in the control of biotechnological processes. Theoretical protein distributions (taking into account the unequal division of yeast cells and the exponential law of protein accumulation during a cell cycle) quantitatively fit experimental distributions, once appropriate variability sources are introduced. Best fits are obtained when the protein threshold required for bud emergence increases at each new generation of parent cells.     

Less label, more free: approaches in label-free quantitative mass spectrometry

In this review we examine techniques, software, and statistical analyses used in label-free quantitative proteomics studies for area under the curve and spectral counting approaches. Recent advances in the field are discussed in an order that reflects a logical workflow design. Examples of studies that follow this design are presented to highlight the requirement for statistical assessment and further experiments to validate results from label-free quantitation. Limitations of label-free approaches are considered, label-free approaches are compared with labelling techniques, and forward-looking applications for label-free quantitative data are presented. We conclude that label-free quantitative proteomics is a reliable, versatile, and cost-effective alternative to labelled quantitation.     

Constitutive expression of heat shock proteins hsp25 and hsp70 in the rat oviduct during neonatal development, the oestrous cycle and early pregnancy

Certain heat shock proteins are regulated by steroid hormones and are associated with oestrogen receptor function in reproductive tissues, indicating that these proteins have a role during implantation, decidualization and placentation. In the present study, the expression of hsp25, hsp70 and oestrogen receptor alpha were examined by immunohistochemistry in oviducts from rats during neonatal development, the oestrous cycle and during early pregnancy. Oestrogen receptor alpha was the first protein observed in the neonatal oviduct, and its expression preceded that of hsp70 and hsp25. Although these heat shock proteins have been associated with the oestrogen receptor, this study showed that during early development of the oviduct, the receptor protein was not associated with the concomitant expression of hsp25 and hsp70. However, these heat shock proteins were expressed when oviductal cells became differentiated. In the adult oviduct, hsp70 was more abundant than hsp25, moreover, there were no significant modifications in expression of hsp25 during the oestrous cycle. In contrast, the expression of hsp70 was significantly higher in epithelial cells during dioestrus, when the maximum amount of oestrogen receptor alpha was also observed. Therefore, the present study shows that hsp70, but not hsp25, is an oviductal protein modulated by the oestrous cycle and that it is a protein marker for specific phases of the oestrous cycle. In addition, hsp70 was more responsive to the hormonal changes in the infundibulum and ampullar regions of the oviduct. During early pregnancy, hsp25 expression was downregulated (unlike in the endometrium), whereas hsp70 was relatively abundant in the oviduct. hsp70 was observed in all functional segments of the oviduct during pregnancy, indicating that in the oviduct, this protein is modulated by oestrogens and progesterone and possibly by other pregnancy-related hormones.     

The impact of high hydrostatic pressure on structure and dynamics of β-lactoglobulin

Methods

Combining small-angle X-ray and neutron scattering measurements with inelastic neutron scattering experiments, we investigated the impact of high hydrostatic pressure on the structure and dynamics of β-lactoglobulin (βLG) in aqueous solution.

Background

βLG is a relatively small protein, which is predominantly dimeric in physiological conditions, but dissociates to monomer below about pH 3.

Results

High-pressure structural results show that the dimer–monomer equilibrium, as well as the protein–protein interactions, are only slightly perturbed by pressure, and βLG unfolding is observed above a threshold value of 3000 bar. In the same range of pressure, dynamical results put in evidence a slowing down of the protein dynamics in the picosecond timescale and a loss of rigidity of the βLG structure. This dynamical behavior can be related to the onset of unfolding processes, probably promoted from water penetration in the hydrophobic cavity.

General significance

Results suggest that density and compressibility of water molecules in contact with the protein are key parameters to regulate the protein flexibility.     

Detection of Tissue Factor Antigen and Coagulation Activity in Coronary Artery Thrombi Isolated from Patients with ST-Segment Elevation Acute Myocardial Infarction

Introduction

Although ruptured atherosclerotic plaques have been extensively analyzed, the composition of thrombi causing arterial occlusion in patients with ST-segment elevation acute myocardial infarction has been less thoroughly investigated. We sought to investigate whether coagulant active tissue factor can be retrieved in thrombi of patients with STEMI undergoing primary percutaneous coronary intervention.

Methods

Nineteen patients with ST-segment elevation acute myocardial infarction referred for primary percutaneous coronary intervention were enrolled in this study. Coronary thrombi aspirated from coronary arteries were routinely processed for paraffin embedding and histological evaluation (4 patients) or immediately snap frozen for evaluation of tissue factor activity using a modified aPTT test (15 patients). Immunoprecipitation followed by immunoblotting was also performed in 12 patients.

Results

Thrombi aspirated from coronary arteries showed large and irregular areas of tissue factor staining within platelet aggregates, and in close contact with inflammatory cells. Some platelet aggregates stained positive for tissue factor, whereas others did not. Monocytes consistently stained strongly for tissue factor, neutrophils had a more variable and irregular tissue factor staining, and red blood cells did not demonstrate staining for tissue factor. Median clotting time of plasma samples containing homogenized thrombi incubated with a monoclonal antibody that specifically inhibits tissue factor-mediated coagulation activity (mAb 5G9) were significantly longer than their respective controls (88.9 seconds versus 76.5 seconds, respectively; p<0.001). Tissue factor was also identified by immunoprecipitation in 10 patients, with significant variability among band intensities.

Conclusions

Active tissue factor is present in coronary artery thrombi of patients with ST-segment elevation acute myocardial infarction, suggesting that it contributes to activate the coagulation cascade ensuing in coronary thrombosis.     

CD38 stimulation lowers the activation threshold and enhances the alloreactivity of cord blood T cells by activating the phosphatidylinositol 3-kinase pathway and inducing CD73 expression

We have recently described in cord blood T cells (CBTC) a novel pathway linking CD38 and CD73, two signal transducers with ecto-enzyme activity. The aim of this study was 2-fold: first, to characterize the mechanisms by which CD38 regulates CD73 expression; and second, to determine whether surface-induced CD73 modulates CBTC responses. A marked increase in CD73 expression was observed in CD38+ cells after incubation with the appropriate CD38 mAbs. The induction of CD73 was blocked by wortmannin, a specific inhibitor of phosphatidylinositol 3-kinase (PI3-K). CD38 stimulation induced tyrosine phosphorylation of the p85 regulatory subunit of PI3-K and its association with other tyrosine-phosphorylated proteins. Surface-induced CD73 was as efficient in delivering activatory signals as the CD73 constitutively expressed on adult T cells. Highly CBTC, totally unresponsive to mitogenic concentrations of plastic-immobilized CD3 mAb, proliferated vigorously when exposed to the combination of plastic-immobilized CD3 and CD73 mAbs. The reactivity to allogeneic irradiated PBMC was also significantly enhanced by CD38 stimulation and was dependent on CD73 expression. Thus, CD38 stimulation lowers the activation threshold of CBTC by the CD3/TCR complex and enhances their reactivity to allogeneic cells via activation of the PI3-kinase pathway and CD73 expression.