Zebrafish Larvae as an Model for Antimicrobial Activity Tests against Intracellular .

Introduction: Blood infections from multi-drug-resistant pose a major health burden. This is especially true because can survive and replicate intracellularly, and the development of new treatment strategies is dependent on expensive and time-consuming trials. The aim of this study was to develop a -infection model that makes it possible to directly observe infections of macrophages and to use this model to test the effect of antimicrobials against intra- and extracellular in order to close the gap between and rodent-infection models.

Importance of aspartyl protease 5 in the establishment of the intracellular niche during acute and chronic infection of Toxoplasma gondii.

Virulence and persistence of the obligate intracellular parasite Toxoplasma gondii involve the secretion of effector proteins belonging to the family of dense granule proteins (GRAs) that act notably as modulators of the host defense mechanisms and participate in cyst wall formation. The subset of GRAs residing in the parasitophorous vacuole (PV) or exported into the host cell, undergo proteolytic cleavage in the Golgi upon the action of the aspartyl protease 5 (ASP5). In tachyzoites, ASP5 substrates play central roles in the morphology of the PV and the export of effectors across the translocon complex MYR1/2/3.

Tissue compartmentalization enables persistence during chemotherapy.

Antimicrobial chemotherapy can fail to eradicate the pathogen, even in the absence of antimicrobial resistance. Persisting pathogens can subsequently cause relapsing diseases. In vitro studies suggest various mechanisms of antibiotic persistence, but their in vivo relevance remains unclear because of the difficulty of studying scarce pathogen survivors in complex host tissues.

Outer membrane permeability: Antimicrobials and diverse nutrients bypass porins in .

Gram-negative bacterial pathogens have an outer membrane that restricts entry of molecules into the cell. Water-filled protein channels in the outer membrane, so-called porins, facilitate nutrient uptake and are thought to enable antibiotic entry. Here, we determined the role of porins in a major pathogen, , by constructing a strain lacking all 40 identifiable porins and 15 strains carrying only a single unique type of porin and characterizing these strains with NMR metabolomics and antimicrobial susceptibility assays.

Regulation of chaperone function by coupled folding and oligomerization.

The homotrimeric molecular chaperone Skp of Gram-negative bacteria facilitates the transport of outer membrane proteins across the periplasm. It has been unclear how its activity is modulated during its functional cycle. Here, we report an atomic-resolution characterization of the Skp monomer-trimer transition.

Disruption of Coronin 1 Signaling in T Cells Promotes Allograft Tolerance while Maintaining Anti-Pathogen Immunity.

The ability of the immune system to discriminate self from non-self is essential for eradicating microbial pathogens but is also responsible for allograft rejection. Whether it is possible to selectively suppress alloresponses while maintaining anti-pathogen immunity remains unknown. We found that mice deficient in coronin 1, a regulator of naive T cell homeostasis, fully retained allografts while maintaining T cell-specific responses against microbial pathogens.

Structural basis for maintenance of bacterial outer membrane lipid asymmetry.

The Gram-negative bacterial outer membrane (OM) is a unique bilayer that forms an efficient permeation barrier to protect the cell from noxious compounds . The defining characteristic of the OM is lipid asymmetry, with phospholipids comprising the inner leaflet and lipopolysaccharides comprising the outer leaflet . This asymmetry is maintained by the Mla pathway, a six-component system that is widespread in Gram-negative bacteria and is thought to mediate retrograde transport of misplaced phospholipids from the outer leaflet of the OM to the cytoplasmic membrane .

PLEKHM1 regulates Salmonella-containing vacuole biogenesis and infection.

The host endolysosomal compartment is often manipulated by intracellular bacterial pathogens. Salmonella (Salmonella enterica serovar Typhimurium) secrete numerous effector proteins, including SifA, through a specialized type III secretion system to hijack the host endosomal system and generate the Salmonella-containing vacuole (SCV). To form this replicative niche, Salmonella targets the Rab7 GTPase to recruit host membranes through largely unknown mechanisms.

Phenotypic variation of Salmonella in host tissues delays eradication by antimicrobial chemotherapy.

Antibiotic therapy often fails to eliminate a fraction of transiently refractory bacteria, causing relapses and chronic infections. Multiple mechanisms can induce such persisters with high antimicrobial tolerance in vitro, but their in vivo relevance remains unclear. Using a fluorescent growth rate reporter, we detected extensive phenotypic variation of Salmonella in host tissues.

Disparate impact of oxidative host defenses determines the fate of Salmonella during systemic infection in mice.

Reactive oxygen and nitrogen species function in host defense via mechanisms that remain controversial. Pathogens might encounter varying levels of these species, but bulk measurements cannot resolve such heterogeneity. We used single-cell approaches to determine the impact of oxidative and nitrosative stresses on individual Salmonella during early infection in mouse spleen.

Parallel exploitation of diverse host nutrients enhances Salmonella virulence.

Pathogen access to host nutrients in infected tissues is fundamental for pathogen growth and virulence, disease progression, and infection control. However, our understanding of this crucial process is still rather limited because of experimental and conceptual challenges. Here, we used proteomics, microbial genetics, competitive infections, and computational approaches to obtain a comprehensive overview of Salmonella nutrition and growth in a mouse typhoid fever model.

Immunity to intracellular Salmonella depends on surface-associated antigens.

Invasive Salmonella infection is an important health problem that is worsening because of rising antimicrobial resistance and changing Salmonella serovar spectrum. Novel vaccines with broad serovar coverage are needed, but suitable protective antigens remain largely unknown. Here, we tested 37 broadly conserved Salmonella antigens in a mouse typhoid fever model, and identified antigen candidates that conferred partial protection against lethal disease.

The anterior T-frame external fixator for high-energy proximal tibial fractures.

The authors' experience using anterior T-frame external fixation combined with percutaneous internal fixation for treatment of high-energy proximal tibial fractures is reported. Thirty-six patients (38 fractures) were reviewed who were treated during a consecutive 42-month period. Three patients died and one patient had an amputation for a Type IIIC open injury, leaving 20 males and 12 females with 21 closed and 13 open fractures (two Type II, seven Type IIIA, three Type IIIB, and one Type IIIC).

[The monorail system--bone segment transport over unreamed interlocking nails].

A treatment protocol is demonstrated, consisting of an osteotomy, either proximal or distal, of the bone defect with subsequent segmental transport via an anteromedially (tibia) or laterally (femur) mounted AO external fixation over an unreamed interlocking nail (monorail system). Twenty patients were treated by this method with indications as follows: 13 had a segmental bone defect of the tibia, 3 of the femur. Three patients showed post-traumatic and postinfectious leg-length discrepancies and one was treated for hypertrophic non-union of the femur.

Influence of type of medullary nail on the development of local infection. An experimental study of solid and slotted nails in rabbits.

Any operation involving the implantation of a foreign body increases the risk of infection. The implant material and its surface, the dead space, and any necrosis or vascular changes play a significant role in susceptibility to infection. We investigated the effect of the dead space in an intramedullary nail on the rate of local infection.

Iatrogenic fractures of the femoral neck during closed nailing of the femoral shaft.

We have reviewed our experience of four iatrogenic femoral neck fractures in 315 consecutive closed intramedullary nailings with the AO/ASIF universal femoral nail. The average neck-shaft angle in the bones that fractured was 139.3 degrees +/- 1.

Segmental transport after unreamed intramedullary nailing. Preliminary report of a "Monorail" system.

The Ilizarov method of segmental bone transport has been shown to be an alternative to more conventional treatments of posttraumatic bony defects. After extensive clinical experience with the unreamed tibial nail in open fractures up to Grade IIIb, a new monorail fixation system for callus distraction and segmental bone transport was devised. This Monorail system is composed of an unreamed intramedullary (IM) nail and a unilateral AO distraction device.

Closed retrograde Hackethal nail stabilization of humeral shaft fractures.

We retrospectively reviewed 48 consecutive humeral shaft fractures treated with Hackethal stacked, flexible, intramedullary (IM) nails. The indications for fixation were polytrauma or fracture patterns not amenable to bracing. The average age of patients was 40 years.

[Primary management of fresh injuries of the thoracic and lumbar vertebrae].

Results of conservative treatment of vertebral body fractures and of repositioning and internal fixation, are compared with those obtained by dorsoventral repositioning and fusion. The results achieved with patients treated by dorsoventral fusion were statistically significantly better than those obtained with the other two treatment methods. Consequently, we modified the treatment concept of thoracic and lumbar vertebral body fractures.

[Validity of nuclear magnetic resonance tomography in evaluation of the traumatized intervertebral disk].

The validity of the magnetic resonance imaging (MRI) in the diagnosis of injured intervertebral discs was examined by a prospective diagnostic study. The golden standard being intraoperative discography. The examinations were carried out on both intervertebral discs adjoining the fractured vertebral body.

[Aggressive debridement and early soft tissue coverage of 3d degree open tibial fractures].

93 patients with grade III open tibial fractures were treated without a treatment protocol from 1980 to 1982. This group is compared to 147 pts. managed between 1983 to 1986 according to a standardized prospectively designed protocol with aggressive debridement augmented by pulsatile Jet-lavage.