Retinoic acid induces changes in Xenopus embryo glycolipid pattern

Retinoic acid (RA), known for its important role in cellular differentiation, may cause a modification of glycolipid distribution characterized by a shift from globoserie towards latto- and ganglio-series. In the present paper, we have investigated the modifications of the lipidic pattern after exogenous RA treatment of Xenopus embryos. We have noticed a decrease in neutral glycolipids with a parallel increase in gangliosides; the content of sulfatides does not seem to be modified. Beside the shift toward ganglio-serie, we have also observed a redistribution inside this class of lipids. In particular, following RA treatment, the relative distribution of GD1b and GT1b increases while that of GM3 decreases.     

Effect of dexamethasone on T-cell receptor/CD3 expression

Glucocorticoid hormones (GCH) are anti-inflammatory and immunosuppressive agents that inhibit T-cell growth and activation. Since the T-cell receptor (TCR)/CD3 complex mediates T-lymphocyte activation, we studied the effect of in vitro dexamethasone (DEX), a synthetic GCH, on TCR/CD3 expression.DEX-treatment of a hybridoma T-cell line and normal un-transformed T-cell clones induced a decrease of the TCR/CD3 membrane expression after 4 days. After 4 weeks, TCR/CD3 was undetectable. However, the amount of mRNAs coding TCR/CD3 chains, including TCR, TCR, CD3, CD3 and CD3, as well as the amount of CD3 protein, a major component of the complex, were unaltered. By contrast, a decrease of the mRNAs deriving from the TCR gene locus, as well as of the TCR protein which is responsible for the membrane expression of the TCR/CD3 complex, was induced.These data suggest that the down-modulation of TCR expression is due to the diminution of TCR gene products in DEX-treated cells. (Mol Cell Biochem 167: 135-144, 1997)     

Collagen-Hydroxyapatite Scaffolds Induce Human Adipose Derived Stem Cells Osteogenic Differentiation In Vitro

Mesenchymal stem cells (MSCs) play a crucial role in regulating normal skeletal homeostasis and, in case of injury, in bone healing and reestablishment of skeletal integrity. Recent scientific literature is focused on the development of bone regeneration models where MSCs are combined with biomimetic three-dimensional scaffolds able to direct MSC osteogenesis. In this work the osteogenic potential of human MSCs isolated from adipose tissue (hADSCs) has been evaluated in vitro in combination with collagen/Mg doped hydroxyapatite scaffolds. Results demonstrate the high osteogenic potential of hADSCs when cultured in specific differentiation induction medium, as revealed by the Alizarin Red S staining and gene expression profile analysis. In combination with collagen/hydroxyapatite scaffold, hADSCs differentiate into mature osteoblasts even in the absence of specific inducing factors; nevertheless, the supplement of the factors markedly accelerates the osteogenic process, as confirmed by the expression of specific markers of pre-osteoblast and mature osteoblast stages, such as osterix, osteopontin (also known as bone sialoprotein I), osteocalcin and specific markers of extracellular matrix maturation and mineralization stages, such as ALPL and osteonectin. Hence, the present work demonstrates that the scaffold per se is able to induce hADSCs differentiation, while the addition of osteo-inductive factors produces a significant acceleration of the osteogenic process. This observation makes the use of our model potentially interesting in the field of regenerative medicine for the treatment of bone defects.     

Polyunsaturated Fatty Acids Attenuate Diet Induced Obesity and Insulin Resistance,Modulating Mitochondrial Respiratory Uncoupling in Rat Skeletal Muscle

Objectives

Omega (ω)-3 polyunsaturated fatty acids (PUFA) are dietary compounds able to attenuate insulin resistance. Anyway, the precise actions of ω-3PUFAs in skeletal muscle are overlooked. We hypothesized that PUFAs, modulating mitochondrial function and efficiency, would ameliorate pro-inflammatory and pro-oxidant signs of nutritionally induced obesity.

Study Design

To this aim, rats were fed a control diet (CD) or isocaloric high fat diets containing either ω-3 PUFA (FD) or lard (LD) for 6 weeks.

Results

FD rats showed lower weight, lipid gain and energy efficiency compared to LD-fed animals, showing higher energy expenditure and O₂ consumption/CO₂ production. Serum lipid profile and pro-inflammatory parameters in FD-fed animals were reduced compared to LD. Accordingly, FD rats exhibited a higher glucose tolerance revealed by an improved glucose and insulin tolerance tests compared to LD, accompanied by a restoration of insulin signalling in skeletal muscle. PUFAs increased lipid oxidation and reduced energy efficiency in subsarcolemmal mitochondria, and increase AMPK activation, reducing both endoplasmic reticulum and oxidative stress. Increased mitochondrial respiration was related to an increased mitochondriogenesis in FD skeletal muscle, as shown by the increase in PGC1-α and -β.

Conclusions

our data strengthened the association of high dietary ω3-PUFA intake with reduced mitochondrial energy efficiency in the skeletal muscle.     

Development of a Short Version of MSQOL-54 Using Factor Analysis and Item Response Theory

BackgroundThe Multiple Sclerosis Quality of Life-54 (MSQOL-54, 52 items grouped in 12 subscales plus two single items) is the most used MS specific health related quality of life inventory.ObjectiveTo develop a shortened version of the MSQOL-54.MethodsMSQOL-54 dimensionality and metric properties were investigated by confirmatory factor analysis (CFA) and Rasch modelling (Partial Credit Model, PCM) on MSQOL-54s completed by 473 MS patients. Their mean age was 41 years, 65% were women, and median Expanded Disability Status Scale (EDSS) score was 2.0 (range 0–9.5). Differential item functioning (DIF) was evaluated for gender, age and EDSS. Dimensionality of the resulting short version was assessed by exploratory factor analysis (EFA) and CFA. Cognitive debriefing of the short instrument (vs. the original) was then performed on 12 MS patients.ResultsCFA of MSQOL-54 subscales showed that the data fitted the overall model well. Two subscales (Role Limitations—Physical, Role Limitations—Emotional) did not fit the PCM, and were removed; two other subscales (Health Perceptions, Social Function) did not fit the model, but were retained as single items. Sexual Satisfaction (single-item subscale) was also removed. The resulting MSQOL-29 consisted of 25 items grouped in 7 subscales, plus 4 single items. PCM fit statistics were within the acceptability range for all MSQOL-29 items except one which had significant DIF by age. EFA and CFA indicated adequate fit to the original two-factor (Physical and Mental Health Composites) hypothesis. Cognitive debriefing confirmed that MSQOL-29 was acceptable and had lost no key items.ConclusionsThe proposed MSQOL-29 is 50% shorter than MSQOL-54, yet preserves key quality of life dimensions. Prospective validation on a large, independent MS patient sample is ongoing.     

Relevant genetic differentiation among Brazilian populations of Anastrepha fraterculus (Diptera,Tephritidae)

We used a population genetic approach to detect the presence of genetic diversity among six populations of Anastrepha fraterculus across Brazil. To this aim, we used Simple Sequence Repeat (SSR) markers, which may capture the presence of differentiative processes across the genome in distinct populations. Spatial analyses of molecular variance were used to identify groups of populations that are both genetically and geographically homogeneous while also being maximally differentiated from each other. The spatial analysis of genetic diversity indicates that the levels of diversity among the six populations vary significantly on an eco-geographical basis. Particularly, altitude seems to represent a differentiating adaptation, as the main genetic differentiation is detected between the two populations present at higher altitudes and the other four populations at sea level. The data, together with the outcomes from different cluster analyses, identify a genetic diversity pattern that overlaps with the distribution of the known morphotypes in the Brazilian area.     

Domain folding and flexibility of Escherichia coli FtsZ determined by tryptophan site-directed mutagenesis

FtsZ has two domains, the amino GTPase domain with a Rossmann fold, and the carboxyl domain that resembles the chorismate mutase fold. Bioinformatics analyses suggest that the interdomain interaction is stronger than the interaction of the protofilament longitudinal interfaces. Crystal B factor analysis of FtsZ and detected conformational changes suggest a connection between these domains. The unfolding/folding characteristics of each domain of FtsZ were tested by introducing tryptophans into the flexible region of the amino (F135W) and the carboxyl (F275W and I294W) domains. As a control, the mutation F40W was introduced in a more rigid part of the amino domain. These mutants showed a native-like structure with denaturation and renaturation curves similar to wild type. However, the I294W mutant showed a strong loss of functionality, both in vivo and in vitro when compared to the other mutants. The functionality was recovered with the double mutant I294W/F275A, which showed full in vivo complementation with a slight increment of in vitro GTPase activity with respect to the single mutant. The formation of a stabilizing aromatic interaction involving a stacking between the tryptophan introduced at position 294 and phenylalanine 275 could account for these results. Folding/unfolding of these mutants induced by guanidinium chloride was compatible with a mechanism in which both domains within the protein show the same stability during FtsZ denaturation and renaturation, probably because of strong interface interactions.