Pathogenesis and prevention of biomaterial centered infections.

One of the major drawbacks in the use of biomedical materials is the occurrence of biomaterials centered infections. After implantation, the host interacts with a biomaterial by forming a conditioning film on its surface and an immune reaction towards the foreign material. When microorganisms can reach the biomaterials surface they can adhere to it.

Temporary, but essential requirement of CD8+ T cells early in the pathogenesis of diabetes in BB rats as revealed by thymectomy and CD8 depletion.

Autoimmunity-prone BB rats demonstrate a T lymphocytopenia and abnormal T cell subset distribution. To test whether the life span of all T cells or only of certain subsets is reduced in BB rats, we thymectomised 8-week-old BB and PVG rats and subsequently assessed size and composition of the T cell population over a 6-week-period. In both strains, thymectomy (Tx) was followed by a decrease in peripheral T cell numbers, which was proportionally larger in BB rats.

Positively charged biomaterials exert antimicrobial effects on gram-negative bacilli in rats.

Biomaterial-centered infection is a much-dreaded complication associated with the use of biomedical implants. Although positively charged biomaterial surfaces stimulate bacterial adhesion, it has been suggested that surface growth of adhering Gram-negative bacilli is inhibited on positively charged surfaces. In the present paper, we determined the infection rate of differently charged poly(methacrylates) in rats.

In vitro and in vivo antimicrobial activity of covalently coupled quaternary ammonium silane coatings on silicone rubber.

Biomaterial-centered infection is a dreaded complication associated with the use of biomedical implants. In this paper, the antimicrobial activity of silicone rubber with a covalently coupled 3-(trimethoxysilyl)-propyldimethyloctadecylammonium chloride (QAS) coating was studied in vitro and in vivo. Gram-positive Staphylococcus aureus ATCC 12600, Staphylococcus epidermidis HBH, 102, and Gram-negative Esherichia coli O2K2 and Pseudomonas aeruginos AK1 were seeded on silicone rubber with and without QAS-coating, in the absence or presence of adsorbed human plasma proteins.

Successful dexamethasone pulse therapy in a toxic epidermal necrolysis (TEN) patient featuring recurrent TEN to oxazepam.

A 62-year-old female patient is described who developed toxic epidermal necrolysis (TEN) after medication with phenytoin and oxazepam. Initially phenytoin was discontinued and dexamethasone pulse therapy (1.5 mg/kg on 3 consecutive days) was initiated on the tenth day of skin disease.

Late hematogenous infection of subcutaneous implants in rats.

Late biomaterial-centered infection is a major complication associated with the use of biomaterial implants. In this study biomaterials that had been implanted subcutaneously in rats were hematogenously challenged with bacteria 4 weeks after implantation. Bacteria were spread either by intravenous injection or by stimulation of bacterial translocation.

Origin of neointimal endothelium and alpha-actin-positive smooth muscle cells in transplant arteriosclerosis.

The development of transplant arteriosclerosis (TA) is today's most important problem in clinical organ transplantation. Histologically, TA is characterized by perivascular inflammation and progressive intimal thickening. Current thought on this process of vascular remodeling assumes that neointimal vascular smooth muscle (VSM) cells and endothelium in TA are graft-derived, holding that medial VSM cells proliferate and migrate into the subendothelial space in response to signals from inflammatory cells and damaged graft endothelium.

Intrathymic immune modulation prevents acute rejection but not the development of graft arteriosclerosis (chronic rejection).

Background: We showed previously that our intrathymic immune modulation protocol induces virtually permanent graft survival of simultaneously transplanted cardiac allografts in MHC-incompatible rat strain combinations. It is, however, unknown whether this procedure prevents the development of graft arterial disease (GAD).

Methods: Male AO recipient rats were intrathymically inoculated with 2.

Recipient origin of neointimal vascular smooth muscle cells in cardiac allografts with transplant arteriosclerosis.

Background: Coronary artery disease is today's most important post-heart transplantation problem after the first perioperative year. Histologically, coronary artery disease is characterized by transplant arteriosclerosis. The current view on this vasculopathy is that vascular smooth muscle (VSM) cells from the media of affected arteries proliferate and migrate into the sub-endothelial space (intima) in response to signals from inflammatory cells and damaged graft endothelium.

Rat cytomegalovirus replication in the salivary glands is exclusively confined to striated duct cells.

The salivary gland is the preferred organ for cytomegalovirus (CMV) replication and viral persistence. In order to identify the nature of infected cells and to study viral replication in more detail, several experiments were conducted. Using the rat CMV (RCMV) model, acutely infected young adult rats (6 weeks of age) and new-born rats (3 days of age) were infected, and submandibular, parotid and sublingual glands were harvested at different time points after infection.

Most marginal zone B cells in rat express germline encoded Ig VH genes and are ligand selected.

The present study was performed to analyze whether marginal zone B (MZ-B) cells in nondeliberately immunized adult rats are selected on basis of the specificity of their B cell receptor, and to determine to what extent memory B cells contribute to the MZ-B cell subset. To this end, the Ig PC7183 V(H) gene repertoire was studied among V(H)DJ(H)-mu transcripts expressed in four sequential stages of B cell development, of two individual untreated adult rats. B cell subsets, i.

Vascular remnants in the rabbit vitreous body. II. Enzyme digestion and immunohistochemical studies.

The purpose of this study was to evaluate the composition of ghost vessels and the newly identified intravitreal structures type 1 and 2 (IVS-1 and 2) observed in the rabbit vitreous body. Rabbit eyes (n = 10, 0.5- approximately 36 months of age) were fixed and embedded in plastic.

Vascular remnants in the rabbit vitreous body. I. Morphological characteristics and relationship to vitreous embryonic development.

Using light and transmission electron microscopy, we observed novel structures in the rabbit vitreous body. They were found in 18 out of 27 eyes from rabbits 0.5-36 months of age.

Chronic allograft rejection associated vasculopathy and synthetic biodegradable vascular grafts: a lesson to learn?

In chronic allografts, graft vessels eventually develop so-called "transplant vascular sclerosis" or "intimal hyperplasia". A major question is whether the cells in the neointima are donor or recipient derived. The process of transplant vascular sclerosis closely resembles the remodeling of the vascular wall as seen when synthetic biodegradable small caliber vascular grafts are implanted.

Single expression of CD45RC and RT6 in correlation with T-helper 1 and T-helper 2 cytokine patterns in the rat.

Previous studies involving the function and development of peripheral T cells have proposed that, in the rat, CD4(+)CD45RC(+)RT6(-) and CD4(+)CD45RC(-)RT6(+) T-cell subsets may represent Th1 and Th2 cells, respectively. Here we tested this hypothesis directly by analyzing frequencies of IFN-gamma- and IL-4-producing cells in these two subpopulations using ELISPOT assays. We found that the CD4(+)CD45RC(-)RT6(+) subset showed higher numbers of IL-4-producing cells than the CD4(+)CD45RC(+)RT6(-) subset and, though less pronounced, that the latter demonstrated higher numbers of IFN-gamma producers.

Homing of negatively charged albumins to the lymphatic system: general implications for drug targeting to peripheral tissues and viral reservoirs.

The present study shows the lymphatic distribution of the negatively charged anti-HIV-1 agents succinylated or aconytilated human serum albumins (HSAs) in rats. Quantitation of blood and lymphatic concentrations of these proteins was performed through fluorescence detection of the fluorescein isothiocyanate (FITC)-labeled proteins. At several time points after i.

Organization of the rabbit vitreous body: lamellae, Cloquet's channel and a novel structure, the 'alae canalis Cloqueti'.

Even though the rabbit is a frequently used animal model for studies on vitreous function and pathobiology, data on the structural organization of the rabbit vitreous are scarce. The aim of the present study is to give a detailed description of rabbit vitreous structure in order to provide a basis for studies on changes in vitreous organization induced by pathophysiological processes. We studied the vitreous body of adult rabbit eyes by complementary anatomical evaluation methods, by light microscopy and by transmission electron microscopy.

The origin of marginal zone B cells in the rat.

The marginal zone is a unique compartment that is only found in the spleen. Rat marginal zone B cells (MZ-B) can be distinguished from other B cells, e.g.

Liver cell proliferation after partial hepatectomy in rats with liver metastases.

Objective: To validate proliferating cell nuclear antigen (PCNA) expression and flow cytometry as proliferation markers in regenerating rat liver containing metastases.

Study Design: Rats containing colorectal liver metastases were killed at various days after 70% partial hepatectomy or a sham operation. [3H]thymidine and 5-bromo-2'deoxyuridine (BrdU) incorporation, PCNA expression and flow cytometry were used to evaluate liver cell proliferation.

Post-thymic T-cell development in the rat.

The presence or absence of CD4, CD8, Thy-1, RT6 and CD45RC revealed a number of T-cell subpopulations in the rat. Vascular thymus transplantation was used in RT7 congenics to establish the lineage relationship between these subpopulations by following phenotypic changes after thymus emigration. We found that recent thymic emigrants exhibit the Thy-1+/RT6-/CD45RC- phenotype and express either CD4 or CD8.