Spider silk constructs enhance axonal regeneration and remyelination in long nerve defects in sheep

BACKGROUND

Surgical reapposition of peripheral nerve results in some axonal regeneration and functional recovery, but the clinical outcome in long distance nerve defects is disappointing and research continues to utilize further interventional approaches to optimize functional recovery. We describe the use of nerve constructs consisting of decellularized vein grafts filled with spider silk fibers as a guiding material to bridge a 6.0 cm tibial nerve defect in adult sheep.

METHODOLOGY/PRINCIPAL FINDINGS

The nerve constructs were compared to autologous nerve grafts. Regeneration was evaluated for clinical, electrophysiological and histological outcome. Electrophysiological recordings were obtained at 6 months and 10 months post surgery in each group. Ten months later, the nerves were removed and prepared for immunostaining, electrophysiological and electron microscopy. Immunostaining for sodium channel (NaV 1.6) was used to define nodes of Ranvier on regenerated axons in combination with anti-S100 and neurofilament. Anti-S100 was used to identify Schwann cells. Axons regenerated through the constructs and were myelinated indicating migration of Schwann cells into the constructs. Nodes of Ranvier between myelin segments were observed and identified by intense sodium channel (NaV 1.6) staining on the regenerated axons. There was no significant difference in electrophysiological results between control autologous experimental and construct implantation indicating that our construct are an effective alternative to autologous nerve transplantation.

CONCLUSIONS/SIGNIFICANCE

This study demonstrates that spider silk enhances Schwann cell migration, axonal regrowth and remyelination including electrophysiological recovery in a long-distance peripheral nerve gap model resulting in functional recovery. This improvement in nerve regeneration could have significant clinical implications for reconstructive nerve surgery.

A novel Respiratory Health Score (RHS) supports a role of acute lung damage and pig breed in the course of an Actinobacillus pleuropneumoniae infection

Background

Bacterial lung infections are a major cause of economic losses in the pig industry; they are responsible for approximately 50% of the antibiotics used in pigs and, therefore, also present an increasing concern to consumer protection agencies. In response to this changing market we investigated the feasibility of an old approach aimed at the breeding selection of more resistant pigs. As a first step in this direction we applied a new respiratory health score system to study the susceptibility of four different pig breeding lines (German Landrace, Piétrain, Hampshire, Large White) towards the respiratory tract pathogen Actinobacillus (A.) pleuropneumoniae.

Results

A controlled experimental aerosol infection with an A. pleuropneumoniae serotype 7 isolate was performed using 106 weaning pigs of defined breeding lines from the breeds German Landrace, Piétrain, Hamphire, and Large White. Pigs were clinically assessed on days 4 and 20 post infection following a novel scoring system, the Respiratory Health Score (RHS), which combines clinical, sonographic and radiographic examination results. The ranking on day 4 was significantly correlated with the ranking based on the pathomorphological Lung Lesion Score (LLS; Spearman Rank Correlation Coefficient of 0.86 [p < 0.0001]). Based on their RHS pigs were assigned to the different quartiles independent of the breeding line. The RHS-based rankings of pigs on day 4 and on day 20 were highly correlated (Spearman Rank Correlation Coefficient of 0.82 [p < 0.0001]) independent of the breeding line. Pigs of the Hampshire line were predominantly found in the lowest scoring quartile (47.6%) and absent in the highest scoring quartile. In contrast, pigs of the German Landrace and Piétrain breeding lines were predominantly found in the highest scoring quartile (32.3% and 35.7%, respectively).

Conclusion

These results demonstrate that the RHS obtained from live pigs shows a highly significant correlation to the lung lesion score considered as a "gold standard". The correlation of the ranking at days 4 and 20 post infection implies that the course of disease is highly dependent on the acute lung damage. The different severity of signs among the tested pig breeding lines clearly suggests a genetic difference in the susceptibility of pigs to A. pleuropneumoniae infection.

[Comparison of the diagnostic significance of clinical, radiographic and ultrasonographic results after an experimental aerosol infection of pigs with Actinobacillus pleuropneumoniae]

Scoring schemes for clinical, ultrasonographic and radiographic findings in pigs were developed based upon a standardized animal model for Actinobacillus pleuropneumoniae infection.The results of these methods were compared to each other as well as with the corresponding pathomorphological findings during necropsy. Altogether 69 pigs of different breeding lines (Hampshire, Pietrain and German Landrace were examined. Positive correlations were found between the results of all three methods as well as with the necropsy scores (p <0.0001). Different pathomorphological findings were detected either by radiographic or by ultrasonographic examination dependent upon the type of lung tissue alterations: Alterations of the pleura as well as sequestration of lung tissue on the lung surface could be clearly identified during the ultrasonographic examination while deep tissue alterations with no contact to the lung surface could be detected reliably by radiographic examination. Both methods complement each other, and the application of a combined ultrasonographic and radiographic examination of the thorax allows a comprehensive inspection of the lung condition. Particularly during the acute phase of the disease the extent of lung tissue damage can be estimated more precisely than by clinical examination alone.

Klinische Symptome bei Ziegen mit Läsionen wie beim Bösartigen Katarrhalfieber

Ziel: Der Fallbericht beschreibt die klinischen Symptome und Befunde sowie die Ergebnisse der labordiagnostischen Untersuchungen von Ziegen mit Läsionen wie beim Bösartigen Katarrhalfieber (BKF). Falldarstellung: Drei Ziegen aus zwei Beständen, in denen auch Schafe gehalten wurden, entwickelten zentralnervöse Ausfallserscheinungen. Zwei lebend vorgestellte Ziegen wiesen meist eine erhöhte Körpertemperatur, Ataxie und Somnolenz auf. Eine Ziege zeigte einen Kopftremor und entwickelte schließlich Durchfall sowie eine Korneatrübung. Die andere fiel durch Drangwandern und verminderte Haltungs- und Stellreaktionen auf, später traten tonisch-klonische Krämpfe auf. Labordiagnostisch zeigten die Tiere Anämie, Hypoproteinämie, erhöhte Leberenzymaktivitäten, zeitweilig Azotämie und Lymphopenie sowie im Liquor eine Pleozytose. 22 bzw. 23 Tage nach Auftreten der ersten Symptome verendeten beide Ziegen. Die dritte, bereits euthanasiert eingelieferte Ziege wurde direkt pathologisch untersucht. In der Sektion fanden sich bei diesen Tieren Vergrößerungen von Lymphknoten, Milz und Leber. Histologisch zeigten sich hochgradige lymphohistiozytäre, teils fibrinoid-nekrotisierende Vaskulitiden in nahezu allen Organen, insbesondere Nieren, Milz, Lunge, Gehirn und Leber. Mittels PCR wurde in verschiedenen Organen DNA des ovinen Herpesvirus Typ 2 (OvHV-2) nachgewiesen. Schlussfolgerungen und klinische Relevanz: Das OvHV-2 ist ein im Schaf persistierendes Virus, das bei einer Infektion von Rindern zum BKF führen kann. Neben Schafen galten Ziegen bisher als reaktionslose Träger dieser Infektion. Der vorliegende Fall zeigt, dass bei Ziegen mit neurologischen Erkrankungen BKF differenzialdiagnostisch berücksichtigt werden muss. Die Diagnose lässt sich vor allem mithilfe pathomorphologischer und molekularbiologischer Untersuchungen bestätigen.

Malignant catarrhal fever-like lesions associated with ovine herpesvirus-2 infection in three goats

This is the first description of malignant catarrhal fever-like lesions associated with ovine herpesvirus-2 (OvHV-2) infection in goats with central nervous symptoms. The diagnosis was based on typical histological lesions characterized by systemic lymphohistiocytic and fibrinoid vasculitis and confirmed by polymerase chain reaction and subsequent phylogenetic analysis of the detected OvHV-2 sequences.

Urolithiasis beim kleinen Wiederkäuer – Behandlungsmethoden und klinische Rekonvaleszenz

Gegenstand und Ziel: Ermittlung der Prognose bei klinisch manifester Urolithiasis des kleinen Wiederkäuers in Abhängigkeit von der Behandlungsstrategie mit besonderem Augenmerk auf die Erfolgsraten zweier Methoden zur temporären Katheterzystostomie. Material und Methode: In einer retrospektiven Studie wurde das therapeutische Vorgehen an Schaf- und Ziegenböcken mit obstruktiver Urolithiasis hinsichtlich der Krankheitsverläufe zusammengefasst und evaluiert. Ergebnisse: Zwischen Januar 2000 und März 2006 wurden 27 Schaf- und 28 Ziegenböcke mit Urolithiasis vorgestellt. Bei 20% der Tiere erfolgte aus wirtschaftlichen Gründen auf Besitzerwunsch oder eines schlechten Allgemeinzustands die Euthanasie ohne Therapieversuch; 20% der Tiere wurden sofort durch eine Katheterzystostomie nach Laparotomie mit temporärer Implantation eines Ballonkatheters versorgt, wovon 57,1% als geheilt entlassen werden konnten. Bei 56,4% aller Patienten fand eine Therapie entsprechend einer Behandlungskaskade“ mit steigender Invasivität statt: Zunächst wurde der Processus urethrae abgesetzt. Bei 45,5% der so behandelten Tiere konnte der Harnfluss wieder hergestellt und die Heilung herbeigeführt werden. Bei 30,3% erfolgte eine chirurgische Versorgung zunächst durch transabdominale Zystostomie mittels Spaltkanüle und transkutaner Implantation eines Ballonkatheters unter Ultraschallkontrolle, die bei zwei Tieren erfolgreich war. Bei einem Bock schloss sich eine erfolgreiche Laparotomie mit erneuter temporärer Katheterzystostomie an, ein weiterer erfuhr eine erfolgreiche Urethrostomie. Die übrigen Tiere wurden wegen ihres schlechten Allgemeinzustandes und auf Besitzerwunsch oder aufgrund von Komplikationen euthanasiert oder verendeten. Schlussfolgerung und klinische Relevanz: Bei kleinen Wiederkäuern mit obstruktiver Urolithiasis bestanden die besten Heilungsaussichten, wenn der Harnfluss bereits durch Absetzen des Processus urethrae wieder hergestellt werden konnte. Gelang dies nicht, bildete die sofortige laparotomische Zystotomie mit temporärer Implantation eines Ballonkatheters die Methode mit dem größten Heilungserfolg. Die transabdominale Katheterzystostomie erwies sich gegenüber dem laparotomischen Vorgehen als unterlegen.

Pressure signal transmission of five commercially available oesophageal balloon catheters

OBJECTIVE

Five commercially available oesophageal balloon catheters (OBCs) were tested to evaluate the accuracy in transmitting fast-changing pressure signals which can be observed, for example, during phrenic nerve stimulation.

SETTING

Research laboratory of a university hospital.

METHOD

The OBCs tested varied in length (900-1390 mm) and inner diameter (0.9-1.5 mm) as well as in balloon material [latex or polyvinylchloride (PVC)]. A 180-cm tube served as a control. A sudden pressure drop was generated by the explosion of a pressurized latex balloon. The time between the pressure drop and 75, 50, 25 and 10% of the maximal pressure was measured.

RESULTS

The time intervals required to transduce a pressure drop of 90% varied between the different OBCs from 85 to 476 ms (control 32 ms). Transmission time was lower in OBCs with a larger inner diameter. Shortening the OBCs resulted in a further decrease in transmission time.

CONCLUSION

The type of OBC used has an impact on signal processing. An OBCs with a short transmission time should be chosen, especially if fast pressure changes are to be evaluated such as during phrenic nerve stimulation.

Transferrin receptor assay and zinc protoporphyrin as markers of iron-deficient erythropoiesis in end-stage renal disease patients

To evaluate storage iron deficiency and iron-deficient erythropoiesis we determined, in a cross-sectional study of 95 patients mainly including end-stage renal disease patients (ESRD) with (32) and without rh-EPO therapy (55), the following parameters: hemoglobin, mean corpuscular red cell volume, ferritin, transferrin saturation (TS), zinc protoporphyrin (ZPP) and soluble transferrin receptor (TfR). In the dialysis group the percentage of positive samples with each marker of tissue iron supply defined as TS < 20%, ZPP > 40 mumol/mol Heme and TfR > 3.05 microgram/ml was as follows: TS 43.7% and 32.2% at a diagnostic threshold level of < 16%, ZPP 33.3% and TfR 17.2%. Manifest storage iron deficiency defined as ferritin < 30 ng/ml was observed in 5.7% of the samples while the mean ferritin concentration of the rh-Epo treated dialysis patients was 509.3 ng/ml compared to 262.5 ng/ml in the group without rh-EPO therapy. These data reflect a generous iron substitution in our series taking a TS < 20% as an intervention criterion. Looking at the different results of the three markers the best correspondence was found between ZPP and TfR resulting in a weak positive correlation (+0.64). In conclusion, we found quite different results with different assays when evaluating endogenous iron availability in our series of mainly ESRD patients in a cross-sectional study. Because a gold-standard is not defined further firm conclusions cannot be drawn from this type of study. The adequacy of the different parameters of iron metabolism including threshold levels and, consequently, the decision and route of iron substitution deserve an evaluation in a longitudinal study to characterize the best marker or marker combination in this setting.

Mutations in the human factor XII gene

The factor XII gene from 31 unrelated factor XII-deficient patients from Germany, Switzerland, and Austria was screened for mutations at the genomic level. Several novel mutations were detected and their absence in a control group of 74 healthy unrelated individuals was checked. Most changes are in the serine protease domain affecting the catalytic triad His-393-Asp-442-Ser-544; two missense mutations, R398Q (arginine 398 to glutamine; gene bank accession no. U71276) and L395M (leucine 395 to methionine; gene bank accession no. U71277), are close to the active site histidine at position 393. Another mutation detected in a cross-reacting material (CRM)-positive female with a history of three abortions affects the active site aspartic acid by changing it to asparagine (D442N; gene bank accession no. U71275). The novel mutation G570R (glycine 570 to arginine; gene bank accession no. U71274) giving rise to a CRM-positive phenotype is located next to Cys571, which forms a vital disulfide bridge. Two mutations are causing reading frame shifts: one single basepair deletion in exon 12 [exon 12: 10590(DelC); gene bank accession no. U71278] and one acceptor splice site mutation [exon 14: 11397(G --> A); gene bank accession no. L43615]. The putative regulatory mutation exon 1:-8 (g --> c) in the upstream region of the gene is associated with an aberrant Taq I restriction site allele in intron B of the gene (gene bank accession no. X80393).

[Variation in inspiratory gas flow in pressure support ventilation. The effect on respiratory mechanics and respiratory work]

During pressure support ventilation (PSV), the timing of the breathing cycle is mainly controlled by the patient. Therefore, the delivered flow pattern during PSV might be better synchronised with the patient's demands than during volume-assisted ventilation. In several modern ventilators, inspiration is terminated when the inspiratory flow decreases to 25% of the initial peak value. However, this timing algorithm might cause premature inspiration termination if the initial peak flow is high. This could result not only in an increased risk of dyssynchronization between the patient and the ventilator, but also in reduced ventilatory support. On the other hand, a decreased peak flow might inappropriately increase the patient's inspiratory effort. The aim of our study was to evaluate the influence of the variation of the initial peak-flow rate during PSV on respiratory pattern and mechanical work of breathing.

PATIENTS

Six patients with chronic obstructive pulmonary disease (COPD) and six patients with no or minor nonobstructive lung pathology (control) were studied during PSV with different inspiratory flow rates by variations of the pressurisation time (Evita I, Drägerwerke, Lübeck, Germany). During the study period all patients were in stable circulatory conditions and in the weaning phase.

METHOD

Patients were studied in a 45 degrees semirecumbent position. Using the medium pressurization time (l s) during PSV the inspiratory pressure was individually adjusted to obtain a tidal volume of about 8 ml/kg body weight. Thereafter, measurements were performed during five pressurization times (< 0.1, 0.5, 1, 1.5, 2 s defined as T 0.1, T 0.5, T 1, T 1.5 and T 2) in random order, while maintaining the pressure support setting at the ventilator. Between each measurement steady-state was attained. Positive end-exspiratory pressure (PEEP) and FIO2 were maintained at prestudy levels and remained constant during the study period. Informed consent was obtained from each patient or his next of kin. The study protocol was approved by the ethics committee of our medical faculty. Gas flow was measured at the proximal end of the endotracheal tube with a pneumotachometer (Fleisch no. 2, Fleisch, Lausanne, Switzerland) and a differential pressure transducer. Tracheal pressure (Paw) was determined in the same position with a second differential pressure transducer (Dr. Fenyves & Gut, Basel, Switzerland). Esophageal pressure (Pes) was obtained by a nasogastric balloon-catheter (Mallinckrodt, Argyle, NY, USA) connected to a further differential pressure transducer of the same type as described above. The balloon was positioned 2-3 cm above the dome of the diaphragm. The correct balloon position was verified by an occlusion test as described elsewhere. The data were sampled after A/D conversion with a frequency of 20 Hz and processed on an IBM-compatible PC. Software for data collection and processing was self-programmed using a commercially available software program (Asyst 4.0, Asyst Software Technologies, Rochester, NY, USA). Patient's inspiratory work of breathing Wpi (mJ/l) was calculated from Pes/ volume plots according to the modified Campbell's diagram. Dynamic intrinsic PEEP (PEEPidyn) was obtained from esophageal pressure tracings relative to airway pressure as the deflection in Pes before the initiation of inspiratory flow Patient's additive work of breathing (Wadd) against ventilator system resistance was calculated directly from Paw/V tracings when Paw was lower than the pressure on the compliance curve. Two-way analysis of variance (ANOVA) was used for statistical analysis, followed by post hoc testing of the least significant difference between means for multiple comparisons. Probability values less than 0.05 were considered as significant.

RESULTS

COPD patients had significantly higher pressure support than control patients. With decreasing inspiratory flow, Wpi increased significantly in COPD patients.(ABSTRACT TRUNCATED)

Organochlorine pesticide accumulation and genotoxicity in Mexican free-tailed bats from Oklahoma and New Mexico

The summer population of Mexican free-tailed bats (Tadarida brasiliensis) at Carlsbad Caverns, New Mexico, declined from an estimated 8.7 million in 1936 to 200,000 in 1974; thereafter, it increased to approximately 700,000 in 1991. This decline has been attributed primarily to organochlorine (OC) pesticide contamination and habitat disturbance. Similar declines have been observed in other populations of this species. This study examined the potential genotoxic effects of OC pesticide contamination on two populations of T. brasiliensis. Pesticide accumulation, frequencies of chromosomal aberrancy, and nuclear DNA content variation in spleen and testicular tissues were examined in specimens collected from Carlsbad Caverns and Vickery Cave, a maternity colony in northwestern Oklahoma, during the summers of 1990 and 1991. Pesticide residues in brain and carcass tissues were identified and quantified by electron capture gas chromatography. Genotoxicity was examined with the standard bone marrow chromosomal aberration assay and flow cytometry. Statistical relationships among pesticide content, observed chromosomal aberrancy, and nuclear DNA content variation were examined. Both populations demonstrated significant levels of DDE contamination; however, the Carlsbad Caverns population showed consistently higher pesticide loads. Males also demonstrated higher levels than females. No statistical differences in chromosomal aberrancy or nuclear DNA content variation were observed among sexes, sites, or collected periods. Positive correlations were detected between brain and carcass DDE concentrations for all bats examined. A significant negative relationship was found between brain DDE concentration and coefficients of variation in spleen DNA content only for males.

Detection of primary HIV infection by a second-generation HIV(p24) antigen test

We studied the course of a primary HIV infection in a 54-year-old woman. Probably the source of infection was sexual intercourse, since other risks, such as i.v. drug use, acupuncture and transfusion were excluded. On admission she presented with fever, a maculopapular rash, and moderate enlargement of nuchal lymph nodes. At that time the anti-HIV 1,2 enzyme immunoassay was negative. However, the HIV-p24 Ag test, which was performed in every HIV screening in our laboratory, was positive. The suspicion of an acute HIV infection was supported by a positive HIV-cDNA-PCR and confirmed by Western blot after seroconversion. As additional finding, the blood smear showed abnormal white cell differential count, indicating viral infection. Aminotransferases were slightly increased, and antibodies to hepatitis B surface and core antigens demonstrated former hepatitis B infection. It is concluded that in this case the HIV-p24 Ag test proved its suitability for early diagnosis of an acute HIV infection. In case of testing blood donors, none of the compulsory serological screening methods would have detected the HIV infection.

[Fulminating E. coli sepsis in Fournier's gangrene]

Fournier's gangrene is a necrotising soft-tissue infection of the scrotum and perineal region caused by gram-negative and gram-positive Enterobacteriaceae. The disease is characterised by its unique appearance, its speed of onset, and its high mortality. CASE REPORT. A 26-year-old male presented to the emergency room complaining of a painful, tremendously swollen scrotum and penis (Fig. 1) that had developed within the past 24 h. Later, slurred speech, pallor, and hypotension were recognised, leading to the patient's admission to the intensive care unit. Suspecting a severe internal haemorrhage, vigorous volume therapy was started using crystalloids and colloids until blood and fresh frozen plasma were available. One hour later, septic shock was presumed and therapy augmented by IV antibiotics, tracheal intubation, and mechanical ventilation. Despite all efforts, the patients condition deteriorated rapidly and he died a few hours later due to multiple organ failure in septic shock. Postmortem, a perforated external hemorrhoidal node was found to be the primary focus of sepsis. Microbiologic cultures revealed Escherichia coli in blood and tissue samples. DISCUSSION. Fournier's gangrene is a rare disease; nevertheless, its clinical picture has to be recognised immediately in order to provide appropriate treatment in time. It occurs predominantly in males after minor trauma, colorectal or urological disease, and perineal or abdominal surgery. Fournier's gangrene usually begins with itching and pain in the scrotal region followed by swelling and dark-blueish discolouration of the scrotum and penis, occasionally including the lower abdominal wall. Fever and chills are usually present. The illness progresses to severe prostation and septic shock with a mortality of 20%-50%. Tissue cultures mostly reveal E. coli, gram-positive enterococci, Pseudomonas, Proteus, and various anaerobes. The treatment should include immediate radical surgical debridement, i.v. administration of broad-spectrum antibiotics, and cardiopulmonary support. CONCLUSION. The dramatic course of Fournier's gangrene requires early recognition, extensive surgical debridement, as well as intensive care treatment in order to prevent irreversible septic shock.

Lithium effect on smooth pursuit eye movements of healthy volunteers

Smooth pursuit eye movement (SPEM) dysfunctions in major affective disorder patients have been reported to be associated with lithium treatment. We report that SPEM of 13 healthy volunteers, either taking lithium (n = 7) or placebo (n = 6), were not significantly impaired by lithium. This could point to a pathophysiologic difference between affective disorder patients and a normal population.

Selective removal of low-density lipoproteins from plasma by polyacrylate-coated Fractogel in vitro and in experimental extracorporeal perfusion

Polyacrylate, covalently bound to Fractogel, was tested as a sorbent for lipoproteins from human plasma in a perfusion column. Experiments in vitro indicated complete elimination of low-density lipoproteins from citrated plasma. No binding of high-density lipoproteins, fibrinogen, or the complement factors C3 and C4 was observed. Biocompatibility was demonstrated by extracorporeal plasma perfusion in sheep. The results indicate the potential use of polyacrylate-coated Fractogel for the removal of low-density lipoproteins from plasma ex vivo.