Implant strategy affects scaffold stability and integrity in cartilage treatment.

PURPOSE: To identify the most appropriate implantation strategy for a novel chondral scaffold in a model simulating the early post-operative phase, in order to optimize the implant procedure and reduce the risk of early failure. METHODS: Eight human cadaveric limbs were strapped to a continuous passive motion device and exposed to extension-flexion cycles (0°-90°). Chondral lesions (1.8 cm diameter) were prepared on condyles, patella and trochlea for the implant of a bi-layer collagen-hydroxyapatite scaffold. The first set-up compared four fixation techniques: press-fit (PF) vs. fibrin glue (FG) vs. pins vs. sutures; the second compared circular and square implants; the third investigated stability in a weight-bearing simulation. The scaffolds were evaluated using semi-quantitative Drobnic and modified Bekkers scores. RESULTS: FG presented higher total Drobnic and Bekkers scores compared to PF (both p = 0.002), pins (p = 0.013 and 0.001) and sutures (p = 0.001 and < 0.0005). Pins offered better total Drobnic and Bekkers scores than PF in the anterior femoral condyles (p = 0.007 and 0.065), similar to FG. The comparison of round and square implants applied by FG showed worst results for square lesions (Drobnic score p = 0.049, Bekkers score p = 0.037). Finally, load caused worst overall results (Drobnic p = 0.018). CONCLUSIONS: FG improves the fixation of this collagen-HA scaffold regardless of lesion location, improving implant stability while preserving its integrity. Pins represent a suitable option only for lesions of the anterior condyles. Square scaffolds present weak corners, therefore, round implants should be preferred. Finally, partial weight-bearing simulation significantly affected the scaffold. These findings may be useful to improve surgical technique and post-operative management of patients, to optimize the outcome of chondral scaffold implantation.

Fibrin glue improves osteochondral scaffold fixation: study on the human cadaveric knee exposed to continuous passive motion.

OBJECTIVE: To evaluate stability and integrity of bi-layer and three-layer collagen-hydroxyapatite (C-HA) osteochondral scaffolds in a human cadaveric knee exposed to continuous passive motion (CPM) with and without loading and the role of added fibrin glue to improve the press-fit fixation of C-HA scaffolds. DESIGN: Osteochondral lesions (2.0 × 1.5 cm) were chiseled out on both condyles and trochlea in eight human cadaveric knees. A total of 24 bi-layer (5 mm, four in each condyle) or three-layer C-HA scaffolds (8 mm, eight in the trochlea, four in each condyle) were first press-fit implanted and underwent testing with CPM, 90 cycles, 0°-90°. The second set of 24 scaffolds was implanted in cleaned lesions with the addition of fibrin glue. Two knees with fibrin glue fixation were additionally exposed to 15 kg loading, with 30 cycles of CPM, 0°-30°. Then, the knees were reopened and the scaffolds were evaluated using semi-quantitative Drobnic and modified Bekkers scores. RESULTS: All but two scaffolds remained in the lesions site throughout CPM. Two implants failed: both were bi-layer osteochondral scaffolds, press-fit implanted at the lateral femoral condyle (LFC). A statistically significant difference was obtained between press-fit and fibrin glue implants with both Drobnic (2.9 ± 0.7 vs 4.3 ± 0.1, P < 0.0005) and Bekkers (3.3 ± 1.0 vs 5.0 ± 0.1, P < 0.0005) scores. Additional knee loading did not affect fibrin glue scaffold fixation or integrity. CONCLUSION: This cadaveric study showed fibrin glue notably improved bi-layer or three-layer C-HA scaffold press-fit fixation regardless of lesion location. It is therefore recommended that fibrin glue be used during surgery to improve early post-operative C-HA scaffold stability and integrity.

Cartilage from the edge of a debrided articular defect is inferior to that from a standard donor site when used for autologous chondrocyte cultivation.

The aim of this study was to evaluate the cultivation potential of cartilage taken from the debrided edge of a chronic lesion of the articular surface. A total of 14 patients underwent arthroscopy of the knee for a chronic lesion on the femoral condyles or trochlea. In addition to the routine cartilage biopsy, a second biopsy of cartilage was taken from the edge of the lesion. The cells isolated from both sources underwent parallel cultivation as monolayer and three-dimensional (3D) alginate culture. The cell yield, viability, capacity for proliferation, morphology and the expressions of typical cartilage genes (collagen I, COL1; collagen II, COL2; aggrecan, AGR; and versican, VER) were assessed. The cartilage differentiation indices (COL2/COL1, AGR/VER) were calculated. The control biopsies revealed a higher mean cell yield (1346 cells/mg vs 341 cells/mg), but similar cell proliferation, viability and morphology compared with the cells from the edge of the lesion. The cartilage differentiation indices were superior in control cells: COL2/COL1 (threefold in biopsies (non-significant)); sixfold in monolayer cultures (p = 0.012), and 7.5-fold in hydrogels (non-significant), AGR/VER (sevenfold in biopsies (p = 0.04), threefold (p = 0.003) in primary cultures and 3.5-fold in hydrogels (non-significant)). Our results suggest that the cultivation of chondrocytes solely from the edges of the lesion cannot be recommended for use in autologous chondrocyte implantation.

Debridement of cartilage lesions before autologous chondrocyte implantation by open or transarthroscopic techniques: a comparative study using post-mortem materials.

We compared the quality of debridement of chondral lesions performed by four arthroscopic (SH, shaver; CU, curette; SHCU, shaver and curette; BP, bipolar electrodes) and one open technique (OPEN, scalpel and curette) which are used prior to autologous chondrocyte implantation (ACI). The ex vivo simulation of all five techniques was carried out on six juvenile equine stifle joints. The OPEN, SH and SHCU techniques were tested on knees harvested from six adult human cadavers. The most vertical walls with the least adjacent damage to cartilage were obtained with the OPEN technique. The CU and SHCU methods gave inferior, but still acceptable results whereas the SH technique alone resulted in a crater-like defect and the BP method undermined the cartilage wall. The subchondral bone was severely violated in all the equine samples which might have been peculiar to this model. The predominant depth of the debridement in the adult human samples was at the level of the calcified cartilage. Some minor penetrations of the subchondral end-plate were induced regardless of the instrumentation used. Our study suggests that not all routine arthroscopic instruments are suitable for the preparation of a defect for ACI. We have shown that the preferred debridement technique is either open or arthroscopically-assisted manual curettage. The use of juvenile equine stifles was not appropriate for the study of the cartilage-subchondral bone interface.

Growth and differentiation of alveolar bone cells in tissue-engineered constructs and monolayer cultures.

The ability to enhance bone regeneration by implanting autologous osteoblasts in combination with an appropriate scaffold would be of great clinical interest. The aim of our study was to compare the growth and differentiation of alveolar bone cells in tissue-engineered constructs and in monolayer cultures, as the basis for developing procedures for routine preparation of bone-like tissue constructs. Alveolar bone tissue was obtained from four human donors and explant cultures of the cells were established. Expanded cells were seeded on macroporous hydroxyapatite granules, and cultured in medium supplemented with osteogenic differentiation factors for up to 3 weeks. Control monolayer cultures were established in parallel, and cultured in media with or without osteogenic supplements. Cell proliferation, alkaline phosphatase (AP) activity and gene expression of AP, osteopontin and osteocalcin were determined under different culture conditions at weekly intervals. Cells in tissue constructs exhibited growth patterns similar to those in control monolayer cultures: enhanced proliferation was noted during the first 2 weeks of cultivation, followed by a decrease in cell numbers. AP activity at 3 weeks was higher in all cultures in osteogenic medium than in control medium. Gene expression levels were stable in monolayer cultures in both types of media whereas, in tissue constructs, they exhibited patterns of osteogenic differentiation. Light and scanning electron microscopy examination of the cell-seeded constructs showed uniform cell distribution, as well as cell attachment and growth into the interior region of the hydroxyapatite granules. Our results show that bone-like constructs with viable cells exhibiting differentiated phenotype can be prepared by cultivation of alveolar-bone cells on the tested hydroxyapatite granules.

[Economy-class syndrome or Immobile Traveler's syndrome?]. / 'Síndrome de la clase turista o síndrome del viajero inmovilizado?

Economy class syndrome describes the situation of patients who suffer pulmonary embolism following prolonged immobility in a long distance flight. The objective of the present study was to analyze whether there is a risk of pulmonary thromboembolism after a long overland journey. The study consecutively enrolled 100 patients diagnosed with pulmonary thromboembolism. Nine of them had previously undertaken a long journey (>5 h), 6 of which had been over land. Consequently, we think that the preventative measures recommended for airline passengers should be extended to users of other means of transport.

¿Síndrome de la clase turista o síndrome del viajero inmovilizado? / Economy class syndrome or immobile traveler´s syndrome?

El síndrome de la clase turista es el que se asocia a personas que presentan una embolia pulmonar a consecuencia de una inmovilización prolongada tras un viaje por vía aérea de larga duración. El objetivo del presente trabajo ha sido analizar si existe riesgo de tromboembolia pulmonar tras un viaje de larga duración por vía terrestre. Se ha estudiado a 100 pacientes consecutivos diagnosticados de tromboembolia pulmonar. De ellos, 9 presentaban el antecedente de haber realizado un viaje prolongado (> 5 h) y en 6 de estos casos el transporte fue terrestre. Por este motivo pensamos que las medidas preventivas propuestas para los viajeros por vía aérea deben extenderse a quienes utilizan otro medio de transporte

Economy class syndrome describes the situation of patients who suffer pulmonary embolism following prolonged immobility in a long distance flight. The objective of the present study was to analyze whether there is a risk of pulmonary thromboembolism after a long overland journey. The study consecutively enrolled 100 patients diagnosed with pulmonary thromboembolism. Nine of them had previously undertaken a long journey (>5 h), 6 of which had been over land. Consequently, we think that the preventative measures recommended for airline passengers should be extended to users of other means of transport

Comparison of four techniques for the fixation of a collagen scaffold in the human cadaveric knee.

OBJECTIVE: Four fixation techniques for a fibrinogen and thrombin coated collagen fleece, used as a scaffold in the cartilage repair, were compared simulating the initial postoperative period in the cadaveric knee joints. METHODS: Full-thickness chondral lesions were made on the medial femoral condyles of seven human cadaveric inferior extremities. Four scaffolds without seeded chondrocytes were implanted into each lesion using four fixation techniques consecutively: self-adhesion without additional material (SA), fibrin sealant (FS), bone sutures (BS), and periosteal cover (PC). After each implantation 150 cycles of continuous passive motion (CPM) were performed. Two cases were additionally exposed to 50 cycles of 10 and 20 kg loading each after the completion of CPM. The scaffolds were evaluated after every 30 cycles, and the fixation strength was tested after the motion was completed. RESULTS: All the SA scaffolds were detached before 60 cycles. The other scaffolds remained stable throughout the testing with only minor disruptions. The endpoint fixation strength was higher for BS and PC than for the FS scaffolds. The FS scaffolds were detached as a result of additional load cycles, while the BS and PC scaffolds showed substantial deformations. CONCLUSION: SA of tested scaffold did not provide sufficient fixation. The FS fixation was easy to perform and assured satisfactory scaffold stability. BS and PC provided excellent scaffold stability, but the techniques were difficult and caused additional injuries. Regardless of the fixation technique used, the tested collagen scaffold may not be exposed to loading in the initial postoperative period.

Viability of human chondrocytes in an ex vivo model in relation to temperature and cartilage depth.

Chondrocytes in human articular cartilage remain viable post-mortem. It has however not been established yet how the storage temperature affects their survival, which is essential information when post-mortem cartilage is used for toxicologic studies. Our aim was to construct a simple model of explanted knee cartilage and to test the influences of time and temperature on the viability of chondrocytes in the ex vivo conditions. Osteochondral cylinders were procured from the cadaveric femoral condyles. The cylinders were embedded in water-tight rubber tubes, which formed separate chondral and osteal compartments. Tubes were filled with normal saline, without additives, to keep chondrocytes under close-to-normal conditions. The samples were divided into two groups stored at 4 degrees C and 35 degrees C, respectively. Three samples of each of these two groups were analysed at the time of removal, and then three and nine days later. Images of Live-Dead staining were scanned by a confocal laser microscope. Count of viable chondrocytes in four regions, from surface to bone, was obtained using image analysis software. The regression model revealed that the number of viable chondrocytes decreased every day by 19% and that an increase in temperature by 1 degree C decreased their viability by 5.8%. The temperature effect fell by 0.2 percentage points for every 100 microm from the surface to the bone. Herein we demonstrate that chondrocytes remain viable in the ex vivo model of human knee cartilage long enough to be able to serve as a model for toxicologic studies. Their viability is, however, significantly influenced by time and temperature.

Inhaled tobramycin in non-cystic fibrosis patients with bronchiectasis and chronic bronchial infection with Pseudomonas aeruginosa.

BACKGROUND: Non-cystic fibrosis (CF) patients with bronchiectasis usually develop chronic bronchial infection with Pseudomonas aeruginosa (PA) that is related to worsening lung function and increased morbidity and mortality. OBJECTIVE: To determine whether direct aerosol delivery of tobramycin to the lower airways may control infection and produce only low systemic toxicity. METHODS: A double-blind, placebo-controlled crossover trial involving 30 patients was conducted to determine the clinical effectiveness and safety of 6-month tobramycin inhalation therapy. Patients received 300 mg of aerosolized tobramycin or placebo twice daily in 2 cycles, each for 6 months, with a one-month washout period. The number of exacerbations, number of hospital admissions, number of hospital admission days, antibiotic use, pulmonary function, quality of life, tobramycin toxicity, density of PA in sputum, emergence of bacterial resistance, and emergence of other opportunistic bacteria were recorded. RESULTS: The number of admissions and days of admission (mean +/- SD) during the tobramycin period (0.15 +/- 0.37 and 2.05 +/- 5.03) were lower than those during the placebo period (0.75 +/-1.16 and 12.65 +/- 21.8) (p < 0.047). A decrease in PA density in sputum was associated with tobramycin administration in the analysis of the first 6-month cycle (p = 0.038). No significant differences were observed in the number of exacerbations, antibiotic use, pulmonary function, and quality of life. The emergence of bacterial resistance and other bacteria did not differ between the 2 periods of study. Inhaled tobramycin was associated with bronchospasm in 3 patients, but not with detectable ototoxicity or nephrotoxicity. CONCLUSIONS: Aerosol administration of high-dose tobramycin in non-CF bronchiectatic patients for endobronchial infection with PA appears to be safe and decreases the risk of hospitalization and PA density in sputum. Nevertheless, pulmonary function and quality of life are not improved, and the risk of bronchospasm is appreciable.

An attempt to estimate students' workload.

Following the recent introduction of the European Credit Transfer System (ECTS) into several European university programs, a new interest has developed in determining students' workload. ECTS credits are numerical values describing the student workload required to complete course units; ECTS has the potential to facilitate comparison and create transparency between institutional curricula. ECTS credits are frequently listed alongside institutional credits in course outlines and module summaries. Measuring student workload has been difficult; to a large extent, estimates are based only upon anecdotal and casual information. To gather more systematic information, we asked students at the Veterinary Faculty, University of Ljubljana, to estimate the actual total workload they committed to fulfill their coursework obligations for specific subjects in the veterinary degree program by reporting their attendance at defined contact hours and their estimated time for outside study, including the time required for examinations and other activities. Students also reported the final grades they received for these subjects. The results show that certain courses require much more work than others, independent of credit unit assignment. Generally, the courses with more contact hours tend also to demand more independent work; the best predictor of both actual student workload and student success is the amount of contact time in which they participate. The data failed to show any strong connection between students' total workload and grades they received; rather, they showed some evidence that regular presence at contact hours was the most positive influence on grades. Less frequent presence at lectures tended to indicate less time spent on independent study. It was also found that pre-clinical and clinical courses tended to require more work from students than other, more general subjects. While the present study does not provide conclusive evidence, it does indicate the need for further inquiry into the nature of the relationship between teaching and learning in higher education and for evaluation of the benefits (or otherwise) of more "self-directed" study.

Anti-Pseudomonas aeruginosa antibody detection in patients with bronchiectasis without cystic fibrosis.

BACKGROUND: Pseudomonas aeruginosa is a frequent cause of infection in patients with bronchiectasis. Differentiation between non-infected patients and those with different degrees of P aeruginosa infection could influence the management and prognosis of these patients. The diagnostic usefulness of serum IgG antibodies against P aeruginosa outer membrane proteins was determined in patients with bronchiectasis without cystic fibrosis. METHODS: Fifty six patients were classified according to sputum culture into three groups: group A (n=18) with no P aeruginosa in any sample; group B (n=18) with P aeruginosa alternating with other microorganisms; and group C (n=20) with P aeruginosa in all sputum samples. Each patient had at least three sputum cultures in the 6 months prior to serum collection. Detection of antibodies was performed by Western blot and their presence against 20 protein bands (10-121 kd) was assessed. RESULTS: Antibodies to more than four bands in total or to five individual bands (36, 26, 22, 20 or 18 kd) differentiated group B from group A, while antibodies to a total of more than eight bands or to 10 individual bands (104, 69, 63, 56, 50, 44, 30, 25, 22, 13 kd) differentiated group C from group B. When discordant results between the total number of bands and the frequency of P aeruginosa isolation were obtained, the follow up of patients suggested that the former, in most cases, predicted chronic P aeruginosa colonisation. CONCLUSION: In patients with bronchiectasis the degree of P aeruginosa infection can be determined by the number and type of outer membrane protein bands indicating which serum antibodies are present.

Bronquiolitis constrictiva y bronquiolitis obliterante con neumonía organizada en las enfermedades sistémicas / Constrictive bronchiolitis and obliterating bronchiolitis with organized pneumonia in systemic diseases

No disponible

[Occupational asthma due to isocyanates: a study of 21 patients]. / Asma ocupacional por isocianatos: estudio de 21 pacientes.

BACKGROUND: A descriptive-evolutive study of a series of patients diagnosed with bronchial occupational asthma due to isocyanate exposure. SUBJECTS AND METHODS: Retrospective study of 21 patients diagnosed with bronchial occupational asthma due to isocyanates. Family story, clinical data, functional respiratory study, allergic and laboratory tests were collected. Clinical and functional performance one year after diagnosis was evaluated in patients who had and who had not stopped causal exposure. RESULTS: 17 men and 4 women aged 22 to 59 years were evaluated. In 5 cases (23.8%) family story of atopy was documented and 12 (57.14%) patients were smokers. Seven out of 21 patients were exposed to paint related products at work being this the most common reason. Average time (SD) from the beginning of exposure to development of symptoms was 16.10 (22.5) months. IgE levels were high in 6 (28.57%) and specific IgE to isocyanates was high in 8 (38%), in all cases bronchial hyperreactivity was detected. In 18 patients (85.7%), the study of maxim expiratory flow (MEF) register demonstrated occupational asthma while in the remaining 3 patients a provocation test was performed with positive result. In the annual follow up visit, the 17 patients who avoided casual exposure showed clinical improvement, 7 of them also with functional improvement while in the remaining 10 patients no significant functional change was observed. On the other hand, 3 of the 4 patients who, although protected, underwent exposure, became clinical and functionally worse (p = 0.003, Fisher test). CONCLUSIONS: The etiology of occupational asthma due to isocyanates is not often assessed and usually lately diagnosed. This aspect is worth considering as the illness prognosis seems related to casual agent avoidance.

[Delayed nonspecific cutaneous hypersensitivity in extrinsic allergic alveolitis and idiopathic pulmonary fibrosis]. / Hipersensibilidad cutánea retardada inespecífica en la alveolitis alérgica extrínseca y en la fibrosis pulmonar idiopática.

BACKGROUND: A study of delayed nonspecific cutaneous hypersensitivity in extrinsic allergic alveolitis and in idiopathic pulmonary fibrosis. METHODS: 13 patients with extrinsic allergic alveolitis, 10 with idiopathic pulmonary fibrosis, 34 with sarcoidosis and a control group of 110 subjects without respiratory disease or apparent defects in cell immunity were evaluated. The skin tests of delayed hypersensitivity were carried out with five antigenic extracts (candidin, staphylococcal toxoid, tuberculin-PPD, trichophyllin, streptokinase-streptodornase). The reactions were read after 48 hours. Delayed nonspecific cutaneous hypersensitivity was globally calculated, both quantitatively (sum of the mean diameters) and quantitatively (overall average of positive reactions). RESULTS: No significant differences were found between the group of patients with idiopathic pulmonary fibrosis and the control group, nor between those with extrinsic allergic alveolitis and those with sarcoidosis. However, differences were found between the control group and the patients with extrinsic allergic alveolitis, both in the quantitative and the qualitative analysis. CONCLUSIONS: Delayed nonspecific cutaneous hypersensitivity in extrinsic allergic alveolitis is depressed in a similar way as in sarcoidosis, whereas it appears to be preserved in idiopathic pulmonary fibrosis. Therefore, extrinsic allergic alveolitis should be considered as another cause of reduction of delayed nonspecific cutaneous hypersensitivity as it is the case with sarcoidosis.