Established beta-adrenergic receptor blocking therapy and acute myocardial infarction. A clinical study of risks and benefits

In order to evaluate the risks and benefits of continuing established therapy with beta-adrenergic receptor blocking drugs during acute myocardial infarction (AMI), 183 consecutive patients, 63 with (beta-blocker group) and 120 without (control group) this therapy, were studied. Detailed information on previous diseases, present symptoms, established medication, clinical and laboratory findings on admission and during the first 12 hours in the CCU was collected. The incidences of congestive heart failure, hypotension, AV blocks and ventricular arrhythmias were not significantly more common in the control group (8 vs. 28%, p less than 0.01). Thus, continuation of established therapy with beta-adrenergic receptor blocking drugs does not seem to increase the risk of complications after hospital admission for AMI. The reason for the low incidence of inferior wall infarction in the beta-blocker group is not clear but it cannot be excluded that when patients on beta-adrenergic receptor blocking therapy develop an inferior AMI, they may run a greater risk of sudden death.     

An established immune response against ovalbumin is suppressed by a transferable serum factor produced after ovalbumin feeding: a role of CD25+ regulatory cells

We have previously demonstrated that rats fed ovalbumin (OVA) develop a tolerogenic activity in serum, which upon transfer induces tolerance to OVA and suppression of the immune response to a bystander antigen. Here, we have extended these studies and analysed if the tolerogenic activity in serum could suppress an established immune response in the recipients. Rats were immunized with OVA, 4 and 1 week prior to the transfer of serum from either OVA-fed or control animals. Rats that received serum from OVA-fed donors had significantly lower delayed-type hypersensitivity (DTH) reaction against OVA 1 week after the serum transfer compared with the controls, and the levels of immunoglobulin (IgG) anti-OVA antibodies were significantly lower 2 and 4 weeks after serum transfer. Monomeric OVA in amounts corresponding to the OVA transferred with serum did not induce the reduction of DTH response or IgG anti-OVA antibody levels. In vitro, the proliferation of OVA-stimulated spleen cells, taken from recipients of tolerogenic serum, was significantly lower compared with spleen cells from the controls. The in vitro suppression seemed to be mediated by a population of CD25+ cells, because the removal of such cells from OVA-stimulated spleen cell suspensions resulted in increased proliferation in cultures from rats receiving tolerogenic serum. Our results showed that the tolerogenic serum factor can suppress an established immune response in recipient animals, possibly through induction of regulatory CD25+ cells. Whether this capacity might be used to influence chronic inflammatory conditions needs to be investigated.     

Prediction of AVM obliteration after stereotactic radiotherapy using radiobiological modelling

This study was carried out in order to derive the radiobiological parameters of the dose-response relation for the obliteration of arteriovenous malformation (AVM) following single fraction stereotactic radiotherapy. Furthermore, the accuracy by which the linear Poisson model predicts the probability of obliteration and how the haemorrhage history, location and volume of the AVM influence its radiosensitivity are investigated. The study patient material consists of 85 patients who received radiation for AVM therapy. Radiation-induced AVM obliterations were assessed on the basis of post-irradiation angiographies and other radiological findings. For each patient the dose delivered to the clinical target volume and the clinical treatment outcome were available. These data were used in a maximum likelihood analysis to calculate the best estimates of the parameters of the linear Poisson model. The uncertainties of these parameters were also calculated and their individual influence on the dose-response curve was studied. AVM radiosensitivity was assumed to be the same for all the patients. The radiobiological model used was proved suitable for predicting the treatment outcome pattern of the studied patient material. The radiobiological parameters of the model were calculated for different AVM locations, bleeding histories and AVM sizes. The range of parameter variability had considerable effect on the dose-response curve of AVM. The correlation between the dosimetric data and their corresponding clinical effect could be accurately modelled using the linear Poisson model. The derived response parameters can be introduced into the clinical routine with the calculated accuracy assuming the same methodology in target definition and delineation. The known volume dependence of AVM radiosensitivity was confirmed. Moreover, a trend relating AVM location with its radiosensitivity was observed.     

Nicotinamide reduces high secretion of IFN-gamma in high-risk relatives even though it does not prevent type 1 diabetes.

Type 1 diabetes (T1D) is an autoimmune disease suggested to be of a T helper (Th)1-like origin. This study aimed to investigate the Th1-like and Th2-like profile in high-risk individuals during the prediabetic phase and the immunologic effect of treatment with nicotinamide. High-risk first-degree relatives of T1D patients participating in the European Nicotinamide Diabetes Intervention Trial (ENDIT) were treated with either nicotinamide or placebo. Peripheral blood mononuclear cells (PBMC) were obtained during the prediabetic phase and close to the onset of manifest T1D and from nondiabetic high-risk individuals. Using the sensitive enzyme-linked immunospot (ELISPOT) technique to distinguish Th1-like from Th2-like lymphocytes, secretion of interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) was analyzed from PBMCs spontaneously and after in vitro stimulation with the diabetes-associated autoantigens, glutamic acid decarboxylase 65 (GAD65, protein and peptide, aa 247-279), recombinant tyrosine phosphatase (IA-2), and heat shock protein (HSP, aa 437-460). High-risk individuals showed high spontaneous as well as autoantigen-induced IFN-gamma secretion. Secretion of IFN-gamma and the IFN-gamma/IL-4 ratio, induced by autoantigens, decreased in individuals developing T1D (p < 0.05), whereas nondiabetic individuals showed an increased IL-4 response (p < 0.05). Thus, a Th1-dominated cytokine profile observed in high-risk individuals inclined toward a diagnosis of diabetes. Nicotinamide caused decreased spontaneous (p = 0.05) and in vitro autoantigen-induced IFN-gamma secretion (p < 0.05) and may play a role in immune regulation, even though it has not been shown to prevent T1D.     

Pore size in implanted polypropylene filters is critical for tissue organization

Widely different implant materials induce surprisingly similar tissue reactions in vivo in contrast to their in vitro responses. Increasing attention has recently been given to the surface texture of the material. When both the material composition and the surface topography are varied, the surface topography seems to be the predominant factor for the induced tissue response. The present study addresses differences in the tissue response to commercially available Millipore mesh filters of polypropylene with pore sizes of 0.6, 10.0 or 30.0 microm. The Millipore filters with adjacent tissue were directly sectioned in a cryostat and evaluated via an immunofluorescence technique with double and triple staining, allowing simultaneous analysis of different antigens in tissue sections. These results show that macrophages, total cells, necrotic cells, nitric oxygen distribution, early angiogenesis, and capsule thickness were influenced by the surface structure. Implants with pore sizes of 0.6 microm, where entrance of inflammatory cells was inhibited, induce the most pronounced foreign body capsule formation. The 10- and 30-microm filters, in contrast, had large amounts of macrophages inside the filter structure, although very few inflammatory cells were found outside the filters. The inflammatory cells within the filters appeared not to influence the foreign body capsule induction. The critical factor for the formation of a foreign body capsule seems to be the localization of implant-close macrophages. Whether this is due to differences in cell activation or in signal transduction to collagen-synthesizing fibroblasts remains an open question.     

Slow axonal transport of soluble proteins and calpain in retinal ganglion cells of aged rabbits.

The rate of slow axonal transport of soluble proteins in retinal ganglion cells of the rabbit decreased with approximately 25% in aged (6 years) compared to previous estimates in adult (2 years) animals. Immunobinding of calpain to microtiter plates coated with a monoclonal antibody to mu-calpain was used to isolate labelled axonally transported mu-calpain from the nerve extracts. It was found that the distribution of labelled mu-calpain in the retrobulbar optic pathway was similar to the distribution profile of the slowly migrating phase of soluble proteins.     

Development of a Cell Patterning Technique Using Poly(Ethylene Glycol) Disilane

A simple technique for controlling cell adhesion on glass substrates by surface modification using a commercially available poly(ethylene glycol) (PEG) disilane, which can bind directly to glass in a single step, in combination with photolithographic micropatterning, was developed, characterized, and evaluated for patterning of HepG2 hepatoma cells and 3T3 fibroblasts. The optimal concentration of PEG-disilane for surface modification was 5 mM, and patterning of strongly adherent cells such as HepG2 required the chelation of divalent metal cations in order to inhibit nonspecific binding and cell aggregation. Whereas the average thickness of the PEG-disilane layer was 18±3.5 nm, the perimeters of patterned areas of exposed glass exhibited ridges of average height 857±50 nm, which may have aided in constraining cell spreading and migration. Although unpatterned PEG-treated substrates were hydrophilic (contact angle 46±1°), micropatterned surfaces behaved as if they were somewhat hydrophobic (contact angle 90°), necessitating special protocols for preventing deleterious dewetting of cells. For optimized protocols, the probability of adhesion of HepG2 cells to a patterned area of exposed glass was almost 15 times higher than the probability of adhesion to a PEG-treated background region of equal area. Our technique is useful for short- to intermediate-term patterning of cell or tissue morphology, e.g., for investigation of the effects of cell–cell interactions or cell geometry.     

KIR down-regulation on NK cells is associated with down-regulation of activating receptors and NK cell inactivation

We previously reported that killer cell immunoglobulin-like receptors (KIR) could be down-regulated from the surface of T cells. Here, we show that KIR down-regulation is also induced on the surface of natural killer (NK) cells upon ligand binding. Common down-regulation characteristics are found on these two cell types: a slow kinetics and a phenomenon observed for long inhibitory forms only. Importantly, KIR down-regulation on NK cells is associated with a down-regulation of activating receptors (CD16, CD2 and 2B4) as well as with a lack of cell responsiveness (antibody-dependent and natural killing activities). This unresponsive state was not observed for MHC-restricted T cells. Our data implicate that, in addition to prevention of the immediate target cell lysis, KIR-MHC class I interactions may also regulate the subsequent NK cell cytotoxic activity. This observation opens new perspectives in the understanding of NK cell regulation.