Variable dystrophin expression in different muscles of a Duchenne muscular dystrophy carrier

The majority of Duchenne muscular dystrophy (DMD) female carriers show dystrophin immunostaining abnormalities, although a significant proportion of clinically non-manifesting carriers are normal following this analysis. We had the opportunity to study dystrophin immunostaining in two different muscles, the vastus lateralis and the rectus abdominis of a possible DMD carrier. While the vastus showed normal dystrophin immunostaining, pathological staining was detected in her rectus abdominis. These findings seem to indicate that dystrophin expression can vary in different muscle groups of a DMD carrier. The implications of these findings in DMD carrier detection and possible dystrophin function are discussed.     

Macrophage antitumor activity in vitro. Comparative analysis of cytolytic, cytostatic, and cytotoxic activities of mouse macrophages and human monocytes

Mouse peritoneal M phi and human blood monocytes were assayed for their antitumor activity in vitro with a cytolysis, a cytostasis and a cytotoxicity test performed in parallel. Both natural and stimulus-induced M phi antitumor capacities were assessed. Results indicate that natural cytolytic activity of unstimulated M phi is generally unable to restrict final tumor cell growth, since it is not coupled with cytostatic capacity. In contrast, exposure of M phi in vitro to either MAF or IFN-beta, besides augmenting M phi cytolytic capacity, induced a very significant cytostatic activity and thus efficiently restricted the survival of tumor cells.     

Biallelic somatic inactivation of the mismatch repair gene MLH1 in a primary skin melanoma

Inactivation of mismatch repair (MMR) genes has been linked to the hereditary nonpolyposis colon cancer syndrome and to a subset of sporadic cancers. A phenotypic characteristic of tumors with defective MMR is microsatellite instability (MSI). Although MSI has been reported in a proportion of cutaneous melanomas, inactivation of MMR genes in this tumor type has not been detected thus far. We recently described a human melanoma cell line, PR-Mel, and a cutaneous metastasis from the same patient, which displayed a MMR defect, and showed high MSI. Here we report that in the PR-Mel cell line both MLH1 alleles are somatically inactivated. One allele is lost through a chromosomal deletion of the region 3p21-24, whereas the remaining allele harbors a G --> A transition at position -1 of the acceptor splice site of intron 15, leading to the in-frame skipping of exon 16. The primary melanoma of the PR patient shows loss of heterozygosity at the BAT21 microsatellite marker, located in the MLH1 gene, and does not express the MLH1 and PMS2 proteins. Moreover, it harbors the same mutation detected in the PR-Mel cells. These results demonstrate that biallelic inactivation of MLH1 had occurred in the primary melanoma of the PR patient and suggest that disruption of MMR might have had a role in the development of the melanoma. This is the first report in which genetic defects leading to disruption of MMR function in a human melanoma have been identified.     

ABCA1 gene deletion protects against cerebral malaria: potential pathogenic role of microparticles in neuropathology

The ATP-binding cassette transporter A1 (ABCA1) modulates the transbilayer distribution of phosphatidylserine at the outer leaflet of the plasma membrane. This external exposure of phosphatidylserine is a hallmark of microparticle production and is impaired in ABCA1(-/-) mice. In this study, we report about the complete resistance to cerebral malaria of these mice. On analysis of histological and systemic parameters we evidenced an impairment of cellular responses to Plasmodium berghei ANKA infection in ABCA1(-/-) mice, as shown by lower plasma tumor necrosis factor levels, a weaker up-regulation of endothelial adhesion molecules in brain microvessels, a reduced leukocyte sequestration, as well as an ablated platelet accumulation. Besides, the number and the procoagulant activity of microparticles were dramatically reduced in the plasma of ABCA1(-/-) compared to ABCA1(+/+) mice. Moreover, microparticles derived from Plasmodium berghei ANKA-infected ABCA1(+/+) mice induced a significant increase of tumor necrosis factor release by noninfected macrophages. In ABCA1(-/-) mice platelet and macrophage responses to vesiculation agonists were ablated and reduced, respectively. Altogether, by pointing out the ABCA1 transporter as a major element controlling cerebral malaria susceptibility, these data provide a novel insight into its pathophysiological mechanisms and are consistent with a pathogenic role of microparticles in this neurological syndrome.     

Asymmetrical hemispheric EEG activation evoked by stimulus position during the Simon task

The Simon effect has been previously shown to be asymmetric at both the behavioral and electrophysiological levels. The present investigation was aimed to clarify whether, during a Simon task, hemispheric asymmetry is also observed in the early phases of stimulus processing. In a group of healthy subjects performing the Simon task, we analyzed scalp potentials evoked by the first lateralized cue (left or right), instead of the classical readiness potential preceding the motor response. ERP results showed a significant left cortical activation to stimuli presented in the right visual field at the 140–160 ms time window. Instead, left stimuli elicited a significant activation of the right versus left hemisphere starting at the next 160–180 ms time interval. We linked this asymmetry to that observed in behavioral data: the Simon effect recorded with left stimuli is smaller than the Simon effect recorded with right stimuli. Results confirm the hypothesis that in right handed subjects, left hemisphere is specialized for motor response selection and is able to process right stimuli faster than the right hemisphere does for left stimuli.     

Phenotype-genotype characterization of 10 families with severe a subunit factor XIII deficiency

Factor XIII (FXIII) deficiency is a very rare severe autosomal bleeding disorder with a frequency of 1:2,000,000 in the general population and only a few patients have been genetically characterized so far. We report a phenotype-genotype characterization of 10 unrelated Iranian patients. Two FXIII (transglutaminase) activity assays showed no FXIII activity, except a conserved residual activity in patients receiving prophylactic substitution treatment. FXIII antigen concentrations measured by two immunoassays were comparable. Genotype characterization identified four novel mutations (2 missense and 2 small deletions) and two previously reported missense mutations in the FXIII A subunit gene (F13A). Molecular modeling was carried out to reveal the structural consequences of the missense mutations, that caused the replacement of an arginine residue involved in the formation of structurally important extensive hydrogen-bonded network. The replacements [c.320G>A (p.Arg77His) in the beta-sandwich, c.868C>T (p.Arg260Cys), c.869G>A (p.Arg260His) and c.1236G>T (p.Arg382Ser) in the core domain] resulted in the loss or impairment of such H-bonded network. Energy decomposition analysis demonstrated that this situation leads to the instability and perhaps to the incorrect folding of the A subunit, that would explain the development of severe FXIII deficiency.     

Genetic control of in vitro natural cell-mediated activity against Salmonella typhimurium by intestinal and splenic lymphoid cells in mice.

In vitro natural anti-bacterial activity against Salmonella typhimurium by lymphocytes from Peyer's patches and spleens was assessed in several mouse strains. C3H/HeN and CBA/J mice, which are resistant to S. typhimurium infections, showed a natural anti-bacterial activity significantly higher than BALB/c, C57BL/10, C57BL/6 and C3H/HeJ mice, i.e. strains susceptible to the in vivo bacterial infection. In these susceptible strains and also in A/J mice, a significantly higher natural activity was observed in females compared to males. The sex control of natural anti-bacterial activity was further stressed by the fact that orchidectomy could induce a strong activity in low responder C57BL/10 male mice. With the exception of Beige mice, a low natural killer (NK) strain also with no natural activity against S. typhimurium in both sexes, the genetic distribution of natural anti-bacterial activity was extremely different from that of the NK activity. Thus, these results further stress the difference between natural anti-bacterial activity and NK cytotoxicity. Furthermore, our data establish a possible link, although with some exceptions, between in vivo susceptibility to S. typhimurium infections and in vitro natural activity against these bacteria.