Pathogenicity of various species of Candida in an experimental murine system

The systemic infection induced by Candida albicans, Candida krusei and Candida viswanathii was studied in an experimental murine system. Candida albicans is able to kill outbred CD1 mice within a few days and at a very low concentration; C. krusei is not pathogenic not even when inoculated at a higher concentration; C. viswanathii is able to kill animals only a a higher concentration. The different resistances do not seem to be under genic control, in as much as the different strains of mice used (hybrid CD2F1 and B6C3HF1, inbred Balb/c) show the same degree of resistance as the CD1 mice to the three species of Candida. The colony forming units (CFU) in the kidneys of CD1 mice inoculated intravenously with 10(5) cells of the three species of Candida, collected at various intervals showed a good correlation with the median survival times: a rapid moltiplication of the C. albicans is evident in the kidneys of the animals 24 hours after the inoculation, while the C. krusei and the C. viswanathii do not moltiply.     

Determination of metabolic equivalents during low- and high-intensity resistance exercise in healthy young subjects and patients with type 2 diabetes

The purpose of this study was to quantify the metabolic equivalents (METs) of resistance exercise in obese patients with type 2 diabetes (T2DM) and healthy young subjects and to evaluate whether there were differences between sessions executed at low- versus high-intensity resistance exercise. Twenty obese patients with T2DM (62.9±6.1 years) and 22 young subjects (22.6±1.9 years) performed two training sessions: one at vigorous intensity (80% of 1-repetition maximum (1RM)) and one at moderate intensity (60% of 1RM). Both groups carried out three strength exercises with a 2-day recovery between sessions. Oxygen consumption was continuously measured 15 min before, during and after each training session. Obese T2DM patients showed lower METs values compared with young healthy participants at the baseline phase (F= 2043.86; P<0.01), during training (F=1140.59; P<0.01) and in the post-exercise phase (F=1012.71; P<0.01). No effects were detected in the group x intensity analysis of covariance. In this study, at both light-moderate and vigorous resistance exercise intensities, the METs value that best represented both sessions was 3 METs for the obese elderly T2DM patients and 5 METs for young subjects.     

Drug treatment in the development of mismatch repair defective acute leukemia and myelodysplastic syndrome

DNA from therapy-related acute leukemia/myelodysplastic syndrome cases (tAL/MDS) from the GIMEMA [Gruppo Italiano Malattie Ematologiche Maligne dell'Adulto] Archive was examined for the microsatellite instability (MSI(+)) phenotype that is diagnostic for defective DNA mismatch repair. More than 60% (16/25) of tAL/MDS cases were MSI(+) in contrast to <4% (0/28) of de novo cases. hMLH1 gene silencing was rare and evidence of promoter methylation was found in less than one-third of the MSI(+) cases. Among the GIMEMA patients who had been treated for breast cancer there was an apparent trend towards early onset primary breast disease. This suggests that there might be common predisposing factors for breast cancer and tAL/MDS. There were also three examples of mutations in the MRE11 gene among the 25 tAL/MDS cases suggesting that defective recombinational DNA repair may promote the development of secondary malignancy. MSI(+) tAL/MDS was significantly associated with previous chemotherapy and the frequency of MSI(+) among radiotherapy patients was considerably lower. In view of the established relationship between drug resistance and mismatch repair defects, we suggest that selection for therapeutic drug resistance may contribute to the incidence of MSI(+) tAL/MDS.     

Membrane charge dependent states of the β-amyloid fragment Aβ (16-35) with differently charged micelle aggregates

Aβ (16-35) is the hydrophobic central core of β-amyloid peptide, the main component of plaques found in the brain tissue of Alzheimer's disease patients. Depending on the conditions present, β-amyloid peptides undergo a conformational transition from random coil or α-helical monomers, to highly toxic β-sheet oligomers and aggregate fibrils. The behavior of β-amyloid peptide at plasma membrane level has been extensively investigated, and membrane charge has been proved to be a key factor modulating its conformational properties. In the present work we probed the conformational behavior of Aβ (16-35) in response to negative charge modifications of the micelle surface. CD and NMR conformational analyses were performed in negatively charged pure SDS micelles and in zwitterionic DPC micelles “doped” with small amounts of SDS. To analyze the tendency of Aβ (16-35) to interact with these micellar systems, we performed EPR experiments on three spin-labeled analogues of Aβ (16-35), bearing the methyl 3-(2,2,5,5-tetramethyl-1-oxypyrrolinyl) methanethiolsulfonate spin label at the N-terminus, in the middle of the sequence and at the C-terminus, respectively. Our conformational data show that, by varying the negative charge of the membrane, Aβ (16-35) undergoes a conformational transition from a soluble helical-kink-helical structure, to a U-turn shaped conformation that resembles protofibril models.     

New functions of XPC in the protection of human skin cells from oxidative damage

Xeroderma pigmentosum (XP) C is involved in the recognition of a variety of bulky DNA-distorting lesions in nucleotide excision repair. Here, we show that XPC plays an unexpected and multifaceted role in cell protection from oxidative DNA damage. XP-C primary keratinocytes and fibroblasts are hypersensitive to the killing effects of DNA-oxidizing agents and this effect is reverted by expression of wild-type XPC. Upon oxidant exposure, XP-C primary keratinocytes and fibroblasts accumulate 8,5'-cyclopurine 2'-deoxynucleosides in their DNA, indicating that XPC is involved in their removal. In the absence of XPC, a decrease in the repair rate of 8-hydroxyguanine (8-OH-Gua) is also observed. We demonstrate that XPC-HR23B complex acts as cofactor in base excision repair of 8-OH-Gua, by stimulating the activity of its specific DNA glycosylase OGG1. In vitro experiments suggest that the mechanism involved is a combination of increased loading and turnover of OGG1 by XPC-HR23B complex. The accumulation of endogenous oxidative DNA damage might contribute to increased skin cancer risk and account for internal cancers reported for XP-C patients.     

Physicochemical characterization of a peptide deriving from the glycoprotein gp36 of the feline immunodeficiency virus and its lipoylated analogue in micellar systems

P59 is the Trp-rich 20-mer peptide ((767)L-G(786)), partial sequence of the membrane-proximal external region (MPER) of the FIV gp36. It has potent antiviral activity, possibly due to a mechanism that inhibits the fusion of the virus with the cell membranes. In the hypothesis that a lipophilic tail could enhance the adhesion of P59 to the membrane so improving its antiviral activity, we synthesized its lipoylated analogue lipo-P59. Fluorescence, CD and NMR investigations in membrane mimicking environments (such as SDS and DPC micelles) were aimed to assess the potential of the lipo-P59 lipophilic tail to affect the biophysical and conformational behaviour of the peptide. In vitro inhibitory assays using lymphoid cell cultures to check the antiviral activity of peptides were also performed. The data show that the biophysical properties and the conformational preferences of the peptides are not dramatically affected by the hydrophobic tail, suggesting that the lipopeptide is capable of preserving all the biophysical peculiarities. Similarly, antiviral experimental data show that the membrane-anchored lipo-P59 peptide is also effective in inhibiting virus replication. Moreover, the lipophilic tail allows P59 to preserve its antiviral activity even in conditions in which the non lipoylated peptide is devoid of activity. In accordance with the unusual high Trp presence, the peptides confirm the preference to be positioned on the membrane interface. Furthermore, the data point out a peculiarity of interaction of the peptides with SDS as compared with DPC.     

Methylation changes at NR3C1 in newborns associate with maternal prenatal stress exposure and newborn birth weight

Early life experiences, including those in utero, have been linked to increased risk for adult-onset chronic disease. The underlying assumption is that there is a critical period of developmental plasticity in utero when selection of the fetal phenotype that is best adapted to the intrauterine environment occurs. The current study is the first to test the idea that extreme maternal psychosocial stressors, as observed in the Democratic Republic of Congo, may modify locus-specific epigenetic marks in the newborn resulting in altered health outcomes. Here we show a significant correlation between culturally relevant measures of maternal prenatal stress, newborn birth weight and newborn methylation in the promoter of the glucocorticoid receptor NR3C1. Increased methylation may constrain plasticity in subsequent gene expression and restrict the range of stress adaptation responses possible in affected individuals, thus increasing their risk for adult-onset diseases.