Molecular epidemiology of macrolide-resistant Streptococcus pneumoniae isolates in Europe

In many European countries, the level of pneumococcal resistance to macrolides has now passed the level of resistance to penicillin G. A total of 82 erythromycin A-resistant isolates of Streptococcus pneumoniae were collected by 11 laboratories in seven European countries. All of the isolates were tested for antimicrobial susceptibility, analyzed for clonal relatedness by multilocus sequence typing, and characterized for macrolide resistance genotypes. The prevalence of the macrolide resistance genotypes varied substantially between countries. In France (87.5% of all strains), Spain (77.3%), Switzerland (80%), and Poland (100%), strains were predominantly erm(B) positive, whereas higher levels of mef(A)-positive strains were reported from Greece (100%) and Germany (33.3%). Macrolide resistance was caused by the oligoclonal spread of some multilocus sequence types, but significant differences in clonal distribution were noted between France and Spain, countries from which high levels of macrolide resistance have been reported. Overall, sequence type 81 (Spain23F-1 clone) was by far the most widespread. The mainly erm(B)-positive serotype 14 clone (sequence type 143), first reported in Poland in the mid-1990s, is now widespread in France.     

Characterization of monocyte-derived dendritic cells in recent-onset diabetes mellitus type 1

Dendritic cells (DC) may play an important role in the immunopathogenesis of type 1 diabetes mellitus (DM-1). In this study, we have analyzed phenotypical changes during cytokine-driven maturation from CD14+ monocytes to mature DC and DC-dependent T-cell stimulation in recent-onset pediatric DM-1 patients and healthy controls. DC maturation was monitored by flow cytometric analyses for the expression of surface markers (HLA-DR, CD1a, CD40, CD80, CD86, CD83, CD14, CD32, mannose-receptor, and CD11c). Flow cytometric analysis of isolated peripheral blood monocytes did not reveal apparent differences between patients and controls. During DC maturation no obvious differences in the expression patterns of surface markers over time or evidence for maturation impairments in DM-1 patients could be appreciated. Solely, a marginal, but significant, transient down-regulation of CD1a on Day 3 (mean MDFI 3.82 vs 7.25; P = 0.021), which was accompanied by an increase of IL-6, could be observed. The comparison of mature DCs (Day 10) between patients and controls indicated no significant differences, except for CD83 (mean MDFI 1.7 vs 1.5; P = 0.042) and CD80 (mean MDFI 15.92 vs 12.73; P = 0.042). Moreover, no difference in T-cell stimulatory capacity was seen. In conclusion, our analysis of a cohort of recent-onset DM-1 patients and controls does not support a role for disease-related alterations in cytokine-driven maturation of monocyte-derived DC.     

Ambiguous Role of Interleukin-12 in Yersinia enterocolitica Infection in Susceptible and Resistant Mouse Strains

Endogenous interleukin-12 (IL-12) mediates protection against Yersinia enterocolitica in C57BL/6 mice by triggering gamma interferon (IFN-γ) production in NK and CD4⁺ T cells. Administration of exogenous IL-12 confers protection against yersiniae in Yersinia-susceptible BALB/c mice but exacerbates yersiniosis in resistant C57BL/6 mice. Therefore, we wanted to dissect the different mechanisms exerted by IL-12 during Yersinia infections by using different models of Yersinia-resistant and -susceptible mice, including resistant C57BL/6 mice, susceptible BALB/c mice, intermediate-susceptible wild-type 129/Sv mice, 129/Sv IFN-γ-receptor-deficient (IFN-γR^−/−) mice and C57BL/6 tumor necrosis factor (TNF) receptor p55 chain-deficient (TNFR p55^−/−) mice. IFN-γR^−/− mice turned out to be highly susceptible to infection by Y. enterocolitica compared with IFN-γR^+/+ mice. Administration of IL-12 was protective in IFN-γR^+/+ mice but not in IFN-γR^−/− mice, suggesting that IFN-γR-induced mechanisms are essential for IL-12-induced resistance against yersiniae. BALB/c mice could be rendered Yersinia resistant by administration of anti-CD4 antibodies or by administration of IL-12. In contrast, C57BL/6 mice could be rendered more resistant by administration of transforming growth factor β (TGF-β). Furthermore, IL-12-triggered toxic effects in C57BL/6 mice were abrogated by coadministration of TGF-β. While administration of IL-12 alone increased TNF-α levels, administration of TGF-β or TGF-β plus IL-12 decreased both TNF-α and IFN-γ levels in Yersinia-infected C57BL/6 mice. Moreover, IL-12 did not induce toxicity in Yersinia-infected TNFR p55^−/− mice, suggesting that TNF-α accounts for IL-12-induced toxicity. Taken together, IL-12 may induce different effector mechanisms in BALB/c and C57BL/6 mice resulting either in protection or exacerbation. These results are important for understanding the critical balance of proinflammatory and regulatory cytokines in bacterial infections which is decisive for beneficial effects of cytokine therapy.     

Activin controls skin morphogenesis and wound repair predominantly via stromal cells and in a concentration-dependent manner via keratinocytes

The transforming growth factor-beta family member activin is a potent regulator of skin morphogenesis and repair. Transgenic mice overexpressing activin in keratinocytes display epidermal hyper-thickening and dermal fibrosis in normal skin and enhanced granulation tissue formation after wounding. Mice overexpressing the secreted activin antagonist follistatin, however, have the opposite wound-healing phenotype. To determine whether activin affects skin morphogenesis and repair via activation of keratinocytes and/or stromal cells, we generated transgenic mice expressing a dominant-negative activin receptor IB mutant (dnActRIB) in keratinocytes. The architecture of adult skin was unaltered in these mice, but delays were observed in postnatal pelage hair follicle morphogenesis and in the first catagen-telogen transformation of hair follicles. Although dnActRIB-transgenic mice showed slightly delayed wound re-epithelialization after skin injury, the strong inhibition of granulation tissue formation seen in follistatin-transgenic mice was not observed. Therefore, although endogenous activin appeared to affect skin morphogenesis and repair predominantly via stromal cells, overexpressed activin strongly affected the epidermis. The epidermal phenotype of activin-overexpressing mice was partially rescued by breeding these animals with dnActRIB-transgenic mice. These results demonstrate that activin affects both stromal cells and keratinocytes in normal and wounded skin and that the effect on keratinocytes is dose-dependent in vivo.     

Dominant-negative soluble PDGF-beta receptor inhibits hepatic stellate cell activation and attenuates liver fibrosis

Hepatic fibrogenesis is a consequence of hepatic stellate cells that become activated and transdifferentiate into a myofibroblastic phenotype with the ability to proliferate and synthesize large quantities of extracellular matrix components. In this process, platelet-derived growth factor (PDGF) is the most potent stimulus for hepatic stellate cell proliferation and migration, and is overexpressed during active hepatic fibrogenesis. This cytokine binds to the PDGF receptor type beta, activates Ras and sequentially propagates the stimulatory signal sequentially via phosphorylation of Raf-1, MEK and the extracellular-signal regulated kinases ERK1/ERK2. Hepatic injury is associated with both increased autocrine PDGF signaling and upregulation of PDGF receptor. In this study, we report that a dominant-negative soluble PDGF-beta receptor consisting of a chimeric IgG containing the extracellular portion of the PDGF receptor type beta blocks HSC activation and attenuates fibrogenesis induced by ligation of the common bile duct in rats. In culture-activated hepatic stellate cells, the soluble receptor blocks phosphorylation of endogenous PDGF receptor, phosphorylation of the ERK1/EKR2 signal and reduces proliferative activities of HSC. In vivo, both the delivery of the purified soluble PDGF antagonist and the administration of adenoviruses expressing the artificial transgene were able to reduce significantly the expression of collagen and alpha-smooth muscle actin. Our results demonstrate that PDGF plays a critical role in the progression and initiation of experimental liver fibrogenesis, and suggest that early anti-PDGF intervention should have a therapeutical impact on the treatment of liver fibrogenesis.     

Experimental pneumococcal meningitis: impaired clearance of bacteria from the blood due to increased apoptosis in the spleen in Bcl-2-deficient mice

Necrotic and apoptotic neuronal cell death can be found in pneumococcal meningitis. We investigated the role of Bcl-2 as an antiapoptotic gene product in pneumococcal meningitis using Bcl-2 knockout (Bcl-2(-/-)) mice. By using a model of pneumococcal meningitis induced by intracerebral infection, Bcl-2-deficient mice and control littermates were assessed by clinical score and a tight rope test at 0, 12, 24, 32, and 36 h after infection. Then mice were sacrificed, the bacterial titers in blood, spleen, and cerebellar homogenates were determined, and the brain and spleen were evaluated histologically. The Bcl-2-deficient mice developed more severe clinical illness, and there were significant differences in the clinical score at 24, 32, and 36 h and in the tight rope test at 12 and 32 h. The bacterial titers in the blood were greater in Bcl-2-deficient mice than in the controls (7.46 +/- 1.93 log CFU/ml versus 5.16 +/- 0.96 log CFU/ml [mean +/- standard deviation]; P < 0.01). Neuronal damage was most prominent in the hippocampal formation, but there were no significant differences between groups. In situ tailing revealed only a few apoptotic neurons in the brain. In the spleen, however, there were significantly more apoptotic leukocytes in Bcl-2-deficient mice than in controls (5,148 +/- 3,406 leukocytes/mm2 versus 1,070 +/- 395 leukocytes/mm2; P < 0.005). Bcl-2 appears to counteract sepsis-induced apoptosis of splenic lymphocytes, thereby enhancing clearance of bacteria from the blood.     

Microproteins in amniotic fluid as an index of changes in fetal renal function during development

Protein content and protein composition were studied in amniotic fluid obtained from 171 healthy pregnant women between the 16th and 38th week of gestation, using microgradient gel electrophoresis to separate proteins according to their molecular size into albumin (68 KD), proteins of low molecular weight (LMW proteins, <68 KD), and proteins of high molecular weight (HMW proteins, >68 KD). Additionally -1-microglobulin (-1-MG, 33 KD) and -2-microglobulin (-2-MG, 11,8 KD) were analysed as micromolecular marker proteins. Concentrations of LMW proteins were 0.15–0.22 g/l, of -1-MG 28.4–34.5 mg/l, and of -2-MG 7.2–11.6 mg/l during the second trimester of gestation, and thereafter decreased progressively to 0.03 g/l, 14.1 mg/l and 2.4 mg/l respectively near term. The same developmental trends were confirmed by calculating the protein/creatinine ratios in amniotic fluid. The concentrations of LMW proteins found in the first postnatal urine of 73 healthy infants born prematurely or at term were similar to those in amniotic fluid of corresponding fetal age. Concentrations of albumin and HMW proteins in postnatal urine were about 5% and 15% respectively when compared with amniotic fluid concentrations. No strong correlation existed between gestational age and either of the analysed proteins which would allow accurate assessment of fetal maturation by protein analysis in amniotic fluid. It is concluded that fetal urinary excretion is the major determinant of the microprotein content of amniotic fluid. Microproteins seem to reflect an increasing tubular reabsorption capacity, which accelerates rapidly after the second trimester of gestation.     

Hydrocephalus in infancy and childhood: diagnosis and indication for operation

Improvement of the prognosis for children suffering from hydrocephalus requires prompt diagnosis and reliable indication of surgical treatment. Today, intrauterine hydrocephalus is detectable within the first three months of pregnancy; in infancy, before the cranial sutures have fused, pathological growth of the head is the principal sign confirming together with anatomical examinations (ultrasound, CT scan) the indication of operative treatment. In later childhood, surgical treatment is only definitely indicated by symptoms and morphological examination of clearly active hypertensive hydrocephalus. Intermittently normotensive hydrocephalus (not "normal-pressure-hydrocephalus"!) showing symptoms adapted to childhood, however, often requires exact examination of intracranial pressure dynamics, including quantitative volume provocation test. "Step-by-step-procedure" is advisable (Table III).     

Using Longitudinal Social Network Analysis to Evaluate a Community-Wide Parenting Intervention

Prevention Science - Harsh parenting attitudes and behaviors negatively impact children’s behavior and development, and are linked to heightened levels of violence in children. Parent...