Modification of collagen matrices for enhancing angiogenesis

The vascularization of engineered tissues in many cases does not keep up with the ingrowth of cells. Nutrient and oxygen supply are not sufficient, which ultimately leads to the death of the invading cells. The enhancement of the angiogenic capabilities of engineered tissues therefore represents a major challenge in the field of tissue engineering. The immobilization of angiogenic growth factors may be useful for enhancing angiogenesis. The most potent angiogenic growth factor specific to endothelial cells, vascular endothelial growth factor (VEGF), occurs in several splice variants. The variant with 165 amino acids both has a high angiogenic activity and a high affinity for heparin. We therefore incorporated heparin molecules into collagen matrices by covalently cross-linking them to amino functions on the collagen. Physical binding of VEGF to the heparin may then prevent a rapid clearance from the implant, while the release rate may become coupled to the degradation of the collagen matrix. The modified matrices were characterized by determination of the extent of the heparin immobilization, the in vitro degradation rate by collagenase. For testing the angiogenic properties, non-modified and heparinized collagen specimens were--either loaded with VEGF or non-loaded--subcutaneously implanted on the back of rats. Specimens were explanted after varying periods of implantation, the dry weights and the hemoglobin contents, as well as immunostained histological sections were evaluated: heparinized collagen matrices loaded with VEGF are vascularized to a substantially higher extent as compared to non-modified matrices.     

Influenza: Diagnosis,epidemiology, prophylaxis

Sans résumé     

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.     

Crystal Containing Membrane Bound Intracellular Inclusion Bodies in the Epithelium of Experimentally Infected Sinus Mucosa

The sinus mucosa of 16 rabbits was experimentally infected with Bacteroides fragilis. This paper describes and discusses large inclusion bodies, which were found in abundance by light and electron microscopy inside ciliated cells of the sinus epithelium in 3 of the studied animals. The spindle-shaped inclusions were located in the apical portion of the cytoplasm. They were bound by a trilaminar membrane with several coils to the interior as well as to the exterior. The interior of an inclusion body consisted to a large extent of electron-lucent, floccular substance, but fibrogranular aggregates and rod-shaped crystals with a line periodicity center-to-center of about 15 nm were also conspicuous. These peculiar formations may be constituted by abnormally stored material from defective synthesis of cilia.     

The use of proteomics in biomarker discovery in neurodegenerative diseases

Biomarkers for neurodegenerative diseases should reflect the central pathogenic processes of the diseases. The field of clinical proteomics is especially well suited for discovery of biomarkers in cerebrospinal fluid (CSF), which reflects the proteins in the brain under healthy conditions as well as in several neurodegenerative diseases. Known proteins involved in the pathology of neurodegenerative diseases are, respectively, normal tau protein, beta-amyloid (1-42), synaptic proteins, amyloid precursor protein (APP), apolipoprotein E (apoE), which previously have been studied by protein immunoassays. The objective of this paper was to summarize results from proteomic studies of differential protein patterns in neurodegenerative diseases with focus on Alzheimer's disease (AD). Today, discrimination of AD from controls and from other neurological diseases has been improved by simultaneous analysis of both beta-amyloid (1-42), total-tau, and phosphorylated tau, where a combination of low levels of CSF-beta-amyloid 1-42 and high levels of CSF-tau and CSF-phospho-tau is associated with an AD diagnosis. Detection of new biomarkers will further strengthen diagnosis and provide useful information in drug trials. The combination of immunoassays and proteomic methods show that the CSF proteins express differential protein patterns in AD, FTD, and PD patients, which reflect divergent underlying pathophysiological mechanisms and neuropathological changes in these diseases.     

Tailoring Antireflux Surgery: A Randomized Clinical Trial

A hypothesis has been formulated that mandates the adjustment of antireflux surgery to either a total or a partial wrap depending on the motor function of the esophagus to avoid dysphagia and other obstructive complaints. This hypothesis has been tested in a randomized, clinical trial where 106 chronic gastroesophageal reflux patients were allocated to either a total Nissen-Rossetti (n= 53) or a Toupet partial posterior (n= 53) fundoplication, irrespective of their preoperative esophageal motor function. All patients were followed at least 3 years, during which time none had a relapse of moderate to severe reflux symptoms. Motor dysfunctions defined as peristaltic amplitude ≤ 30 mmHg in the distal third and failed primary peristalsis with or without > 20% simultaneous contractions were noted in 67 patients preoperatively, but these patients did not have a specific symptom profile (e.g., dominated by obstructive symptoms) nor did seven patients with “aperistaltic esophagus.” The incidence of dysphagia decreased from 20% preoperatively to 8% (mild) at 3 years after the operation with no difference between the surgical procedures. We were unable to demonstrate a relation between preoperative manometric findings and postoperative symptoms when assessed in the total group or when subdivided by the type of fundoplication (r < 0.3). Flatulence occurred more frequently among those with a total fundic wrap (p < 0.01). When patients representing motor dysfunction (see above) were specifically analyzed, we again observed no difference in outcome between those having a total or a partial fundic wrap. In conclusion, the concept of tailoring antireflux surgery based on the preoperative motor function of the esophagus in patients with chronic gastroesophageal reflux disease was not supported by the results of this clinical trial.     

Day care attendance, recurrent respiratory tract infections and asthma

OBJECTIVE: Our objective was to use a causal model for childhood asthma to determine whether the effect of day care attendance on asthma was mediated by recurrent respiratory tract infections. DESIGN: A cross-sectional survey among 1447 children aged 6-16 years in Oslo. Their parents completed written questionnaires. A recursive logit model was used to estimate direct effects in terms of adjusted odds ratios (aOR). RESULTS: Year of birth, number of siblings and length of maternal education were significantly associated with day care attendance. Attendance at day care increased the risk of early infections, aOR = 1.8 (1.3-2.5), and infections were associated with asthma, aOR = 4.9 (3.4-7.3). The crude association between day care and asthma was cOR = 1.5 (1.0-2.2), whereas the estimated direct effect was small and nonsignificant, aOR = 1.2 (0.8-1.9). The results may be influenced by overreporting of infections among parents of children with asthma. CONCLUSIONS: Our results suggest that children who attend day care have an increased risk of asthma with early infections as a mediator of risk.     

Lesion pattern in patients with multiple sclerosis and depression

To assess if a specific lesion pattern or changes of the basal limbic system as seen in primary depression and depression associated with neurodegenerative disorders might be identified in depressive multiple sclerosis (MS) patients, we submitted 78 MS patients to a MRI examination consisting of a quantitative measurement of lesions and of hyperintense signals from the pontomesencephalic midline (raphe). Furthermore relaxometry of the pontomesencephalic midline, a transcranial ultrasound examination rating its echogenicity semiquantitatively and a standardized neurological, neuropsychiatric and neuropsychological assessment were obtained. Thirty-one patients fulfilled the DSM-IV criteria for depression. Depressed MS patients had a significantly larger temporal lesion load than non-depressed MS patients, especially on the right side. A trend of difference was detected for lesions of the right parietal lobe, the right frontal lobe, the cerebellum and the total lesion load. Neither hyperintense signals or relaxometry nor echogenicity of the region at the level of the pontomesencephalic midline were significantly different between the groups. We conclude that depression in MS patients is not associated with an alteration of the basal limbic system at the brainstem as seen in Parkinson's disease or unipolar depression but with an increased lesion load of the projection areas of the basal limbic system.