Novel Y-chromosome short tandem repeats in Sus scrofa and their variation in European wild boar and domestic pig populations.

Y-chromosome markers are important tools for studying male-specific gene flow within and between populations, hybridization patterns and kinship. However, their use in non-human mammals is often hampered by the lack of Y-specific polymorphic markers. We identified new male-specific short tandem repeats (STRs) in Sus scrofa using the available genome sequence. We selected four polymorphic loci (5-10 alleles per locus), falling in one duplicated and two single-copy regions. A total of 32 haplotypes were found by screening 211 individuals from eight wild boar populations across Europe and five domestic pig populations. European wild boar were characterized by significantly higher levels of haplotype diversity compared to European domestic pigs (HD  = 0.904 ± 0.011 and HD  = 0.491 ± 0.077 respectively). Relationships among STR haplotypes were investigated by combining them with single nucleotide polymorphisms at two linked genes (AMELY and UTY) in a network analysis. A differentiation between wild and domestic populations was observed (FST  = 0.229), with commercial breeds sharing no Y haplotype with the sampled wild boar. Similarly, a certain degree of geographic differentiation was observed across Europe, with a number of local private haplotypes and high diversity in northern populations. The described Y-chromosome markers can be useful to track male inheritance and gene flow in wild and domestic populations, promising to provide insights into evolutionary and population genetics in Sus scrofa.

Delayed delivery of the second twin: Case report and literature review of diamniotic dichorionic twin pregnancy with very early preterm premature rupture of membranes.

In multiple pregnancies with threatened premature delivery or preterm premature rupture of membranes (pPROM) of a single sac, prolonging pregnancy after the delivery of the first baby may improve the chances of survival of the second baby. We report the delayed delivery of a second baby in a twin pregnancy with pPROM and very premature delivery of the first baby. This condition is exceptional and there are no validated medical protocols for its management; the scientific evidence is still controversial. In our case, after the birth of the first baby, pregnancy was continued for 29 days, with monitoring of maternal and fetal parameters, which enabled the delivery of the second baby with improved neonatal outcomes. This case supports the prolongation of the pregnancy of the second twin.

Macrolide-resistance mechanisms in Streptococcus pneumoniae isolates from Belgium.

Of 233 erythromycin-resistant pneumococcal isolates collected in Belgium in 1999-2000, 89.7% carried the erm(B) gene, 6% the mef(A) gene, and 3.5%erm(B) plus mef(A). Two isolates contained neither erm(B) nor mef(A); one contained an erm(A) subclass erm(TR) gene, while the other contained an A2058G mutation in domain V of the 23S rRNA gene. Of 209 erm(B)-positive isolates, 191 had clindamycin MICs > 16 mg/L and 18 had MICs < or = 16 mg/L. Mef(A)-positive isolates all displayed the M resistance phenotype. Telithromycin remained active against erythromycin-resistant isolates, with the highest telithromycin MIC50 being found in mef(A)-positive isolates. No difference in the prevalence of different resistance mechanisms was observed compared to isolates collected in 1995-1997.

Overcoming bacterial resistance by dual target inhibition: the case of streptogramins.

Streptogramins A and B are chemically unrelated antimicrobials which act synergistically. This synergy is responsible for enhanced activity of the combination compared to each of the components and allows to overcome certain mechanisms of resistance to streptogramins B.. Although not completely elucidated, the mechanism of synergy is unique and based on a stable ribosome conformational change provoked by the binding of streptogramins A which unmasks a high affinity binding site for streptogramins B. A variety of resistance mechanisms to the A or B components by drug inactivation, target site modification, and active efflux have been reported. Acquired resistance to streptogramins A partially alters the synergy between the streptogramins A and B confirming the role of this component in the synergy. Full resistance in clinical isolates is due to combinations of genes for resistance to both components often associated on a single plasmid. Recently, a mutation in the L22 ribosomal protein of Staphylococcus aureus was found to confer resistance to streptogramins B and to abolish the synergy between A and B, probably by perturbing the association of this protein with 23S rRNA.

Coxsackie B3 virus can replicate in cultured human foetal heart cells and is inhibited by interferon.

Coxsackie B viruses (types 1 to 5) are the most frequent reported cause of acute viral myocarditis. To study the pathogenesis of the disease at the cellular level, we simulated an infectious situation by infecting cultured human foetal heart cells with Coxsackie B3 (CB3) virus. Successful replication of this virus could be demonstrated by the presence of virus particles inside cultivated foetal myocytes together with high titres of progeny virus of 10(8) plaque-forming units (PFU) per millilitre culture medium. Within 9 h of infection networks of myocytes lost their ability to contract spontaneously followed by disintegration and replacement by overgrowing fibroblasts which survived the infection. These cells produced CB3 virus continuously over several months, indicating carrier state infection of human myocardial fibroblasts. Human fibroblasts interferon (IFN-beta) was found to act as a potent inhibitor of the replication of this virus. Virus yields could be reduced from 1.2 x 1.8 x 10(5) PFU/ml culture medium when human heart cells were incubated with IFN-beta 20 h prior to challenge with a high input multiplicity of 50 PFU of CB3 virus per cell, demonstrating the major protective role of IFN-beta in CB3 viral infection. It thus appear that IFN-beta might become useful as an antiviral agent in the treatment of Coxsackie myocarditis.

[Detection and localization of a ribonuclease activity associated with vaccinia virus]. / Mise en évidence et localisation d'une activité ribonucléase associée au virus de la vaccine.

A ribonuclease associated with vaccinia virus can be detected when reduced concentrations of nucleotides are used for an in vitro RNA synthesis assay. The non-viral origin of this ribonuclease may be inferred from its external location and from its variable activity on different purified virus stocks. The detection of this ribonuclease activity on purified virus grown without foetal Calf serum may suggest that this enzyme is of cellular origin.

Ongoing enterovirus-induced myocarditis is associated with persistent heart muscle infection: quantitative analysis of virus replication, tissue damage, and inflammation.

Coxsackievirus B3-induced myocarditis in different immunocompetent mouse strains was used as a model to investigate interrelationships between virus replication and development of chronic enteroviral heart disease. Using in situ hybridization to detect enteroviral RNA, we show that heart muscle infection is not only detected in acute myocarditis but is also detected during the chronic phase of the disease. Coxsackievirus B3 could evade immunological surveillance in a host-dependent fashion, thus inducing a persistent infection of the myocardium in association with ongoing inflammation. Patterns of acute and persistent myocardial infection were quantitatively assessed in one representative mouse strain (A.CA/SnJ, H-2f) by applying computer-assisted digital image processing; these patterns were then related to the extent of myocardial tissue damage as well as to inflammation. We observed a strong correlation, both spatial and temporal, between viral replication and development of myocardial lesions, indicating that acute and chronic myocardial injuries are a consequence of multifocal organ infection. Analysis of strand-specific in situ hybridization revealed that viral replication in persistent infection is restricted at the level of RNA synthesis. The described procedure for quantitating organ infection provides a powerful tool for evaluating virus-host interactions and will be of particular interest to those studying human enterovirus-induced cardiomyopathies.

In situ detection of enteroviral genomes in myocardial cells by nucleic acid hybridization: an approach to the diagnosis of viral heart disease.

We have developed an in situ hybridization assay capable of detecting enteroviral RNA in myocardial cells, using molecularly cloned coxsackievirus B3 cDNA as a diagnostic probe. Because of the high degree of nucleic acid sequence homology among the numerous enteroviral serotypes, including the group A and B coxsackieviruses and the echoviruses, detection of these various agents commonly implicated in human viral heart disease is possible in a single hybridization assay. We demonstrate the considerable potential of this method for an unequivocal diagnosis of enteroviral heart disease as well as for pathogenicity studies. Using athymic mice persistently infected with coxsackievirus B3 as a model system, we show that the myocardium is affected in a disseminated, multifocal manner.

Synergistic interaction of interferon-beta and interferon-gamma in coxsackievirus B3-infected carrier cultures of human myocardial fibroblasts.

The antiviral effects of human interferon-beta (IFN-beta) and human recombinant interferon-gamma (rIFN-gamma) were studied in persistently coxsackievirus B3-infected carrier cultures of human myocardial fibroblasts over a period of 21 days. Synergism was observed with concentrations as low as 30 IU of IFN-beta plus 10 IU of rIFN-gamma/mL, reducing mean viral titers from 6.0 x 10(7) to 1.3 x 10(4) pfu/mL and number of infected cells from 14.4% to 0.1% as determined by quantitative in situ hybridization. Higher concentrations of IFNs (both > or = 30 IU/mL) were associated with transient antagonism followed by antiviral synergism. With 100 IU of IFN-beta plus 30 IU of rIFN-gamma/mL, elimination of infectious virus was consistently achieved and sustained for 6 weeks after cessation of IFN application, whereas at least threefold higher concentrations were required with single drugs. In summary, our data support a concept of low-dose IFN combination schedules that might become useful in the treatment of enteroviral heart disease.