Cell biological and biomechanical evaluation of two different fixation techniques for rotator cuff repair.

Our objective was to evaluate the cell biology and biomechanical aspects of the healing process after two different techniques in open rotator cuff surgery - double-loaded bio-absorbable suture anchors combined with so-called arthroscopic Mason-Allen stitches (AAMA) and a trans-osseous suture technique combined with traditional modified Mason-Allen stitches (SMMA). Thirty-six mature sheep were randomized into two repair groups. After 6, 12, or 26 weeks, evaluation of the reinsertion site of the infraspinatus tendon was performed. The mechanical load-to-failure and stiffness results did not indicate a significant difference between the two groups. After 26 weeks, fibrocartilage was sparse in the AAMA group, whereas the SMMA group showed the most pronounced amount of fibrocartilage. We found no ultrastructural differences in collagen fiber organization between the two groups. The relative expression of collagen type II mRNA in the normal group was 1.11. For the AAMA group, 6 weeks after surgery, the relative expression was 55.47, whereas for the SMMA group it was 1.90. This in vivo study showed that the AAMA group exhibited a tendon-to-bone healing process more favorable in its cell biology than that of the traditional SMMA technique. Therefore, the AAMA technique might also be more appropriate for arthroscopic repair.

[Evaluation of cartilage defects in the knee: validity of clinical, magnetic-resonance-imaging and radiological findings compared with arthroscopy]. / Diagnostik von Knorpelschäden des Kniegelenks: Validität der klinischen, radiologischen und kernspintomographischen Diagnostik im Vergleich zur Arthroskopie.

BACKGROUND: The study was aimed to evaluate the validity of clinical, radiological and MRI examination for cartilage defects of the knee compared with arthroscopic finding. METHODS: Seven-hundred seventy-two patients who were suffering from knee pain over more than 3 months were evaluated clinical (grinding-sign) and with radiography and magnetic resonance imaging (MRI) and subsequent arthroscopy. RESULTS: The grinding sign had a sensitivity of 0.39. The association of a positive grinding test with high grade cartilage defects was significant (p<0.000). In 97.4% an intact chondral surface correlated with a normal radiological finding. Subchondral sclerosis, exophytes and a joint space narrowing was significantly associated with high grade cartilage defects (p<0.000). The accuracy of MRI was 59.5%. The MRI resulted in an overestimation in 36.6% and an underestimation in 3.9%. False-positive results were significant more often assessed in low-grade cartilage defects (p<0.000). CONCLUSIONS: Clinical signs, x-ray imaging and MRI correlate with arthroscopic findings in cases of deep cartilage lesions. In intact or low-grade degenerated cartilage often results an overestimating of these findings.

Autologous chondrocyte transplantation for treating cartilage defects of the talus.

BACKGROUND: Despite its highly specialized nature, articular cartilage has a poor reparative capability. Treatment of symptomatic osteochondral defects of the talus has been especially difficult until now. METHODS: We performed autologous chondrocyte transplantation in twelve patients with a focal deep cartilage lesion of the talus. There were seven female and five male patients with a mean age of 29.7 years. The mean size of the lesion was 2.3 cm(2). All patients were studied prospectively. Evaluation was performed with use of the Hannover ankle rating score, the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, a visual analogue scale for pain, and magnetic resonance imaging. RESULTS: All patients were available for follow-up at a mean of sixty-three months. There was a significant improvement in the Hannover score, from 40.4 points preoperatively to 85.5 points at the follow-up examination, with seven excellent results, four good results, and one satisfactory result. The AOFAS mean score was 88.4 points compared with 43.5 points preoperatively. Magnetic resonance imaging showed a nearly congruent joint surface in seven patients, discrete irregularities in four, and an incongruent surface in one. The patients who had been involved in competitive sports were able to return to their full activity level. CONCLUSIONS: The promising clinical results of this study suggest that autologous chondrocyte transplantation is an effective and safe way to treat symptomatic osteochondral defects of the talus in appropriately selected patients.

Factors that influence high tibial osteotomy results in patients with medial gonarthritis: a score to predict the results.

OBJECTIVE: High tibial osteotomy (HTO) for the treatment of unicompartmental knee osteoarthritis in the presence of axial malalignment is recognized as an effective treatment for young and active patients. The aim of this study was to identify HTO prognostic factors. METHODS: A total of 94 patients who had undergone HTO with additive arthroscopy were scored using the "knee injury and osteoarthritis outcome score" (KOOS). A KOOS of less than 114 points was judged as a poor outcome. RESULTS: A total of 84 patients were available for follow-up after a time-interval of 45.9+/-7.6 (range 34-60) months. The KOOS increased from 46.1+/-11.1 to 120.3+/-40.8. The preoperative varus angle in all patients was 7.5 degrees +/-1.9 (range 5-14 degrees ). In follow-up the patients had a mean valgus angle of 3.7 degrees +/-2.5. Twenty-three patients (27.4%) had suffered a loss of correction (0.8 degrees , range 0-2 degrees ). A loss of correction correlated with a minor result in tendency. A total of 25 patients (29.8%) had a poor KOOS. Factors associated with a poor HTO outcome were a patient history of more than 24 months, a preoperative KOOS>50 points, obesity, and smoking. However, the results were also influenced by radiological findings, such as medial tibial exophyte, a medial joint space width of less than 5mm, and intraarticular damage, such as a degree IV cartilage defect of the tibia. Gender was also a minor prognostic factor. Patient's age and the event of prior surgery did not influence the outcome. CONCLUSION: This study identified relevant factors that significantly influenced HTO results. It was possible to create a "predictive score" for HTO patients. Patients with more than 4 of the poor prognostic factors should chose primary arthroplasty.

Clinical outcome of the arthroscopic management of sports-related "anterior ankle pain": a prospective study.

Anterior impingement syndrome is a generally accepted diagnosis for a condition characterized by anterior ankle pain with limited and painful dorsiflexion. The cause can be either soft tissue or bony obstruction. We reviewed 26 (16 male and 10 female) athletes with a mean age of 27 years treated arthroscopically for symptoms due to soft-tissue (group I, n = 12) and bony obstruction (group II, n = 14). They suffered from anterior pain, reduction of dorsiflexion and recurrent swelling with severe impairment in their sports activities. There was no clinical improvement for at least 6 months despite of conservative treatment with a mean duration of symptoms about 20 months. There were no further operations. Evaluation included the Karlsson ankle rating score, the activity score of Tegner, and a visual analogue scale (VAS) reflecting patients' pain. Conventional radiographs and Magnetic resonance imaging (MRI) were done preoperatively. All patients were available for follow up after 31 months (range, 25-48 months) with a significant improvement (p < 0.05) of the Karlsson score from 66 to a mean of 92 at the follow-up examination. The mean Tegner score was eight points compared to three points preoperatively. Regarding the subjective assessment observed by the decrease of pain and the ability of the athelete to return to competition sport, there were 25 very satisfied and one unsatisfied athlete. No significant difference in the outcome of group I and II (p > 0.05) could be estimated. The results demonstrate ' excellent ' to ' good ' results for arthroscopic treatment of sports-related anterior ankle pain in a group of athletes who were involved in competition sport. The promising clinical results confirm an effective way of treating soft-tissue and bony impingement. In addition, we recommend prior to surgery, an adequate course of non-operative treatment, including modifications in the exercise program and athletic activity.

Human phosphatidylethanolamine-binding protein facilitates heterotrimeric G protein-dependent signaling.

In this study we report that human phosphatidylethanolamine-binding protein (hPBP) facilitates heterotrimeric G protein-coupled signaling. In Xenopus laevis oocytes, coexpression of hPBP with human mu opioid receptor, human delta opioid receptor, or human somatostatin receptor 2 evoked an agonist-induced increase in potassium conductance of G protein-activated inwardly rectifying potassium channels. This activation of heterotrimeric G protein signaling in oocytes could also be elicited by injection of bacterially overexpressed and purified hPBP. Stimulatory effect was pertussis toxin-sensitive and present even in the absence of coexpressed receptors. Additionally, an increase in G protein-mediated inhibition of adenylate cyclase activity, measured by the inhibition of forskolin-mediated cAMP accumulation, could be detected in HEK293 and NIH3T3 cells after expression of hPBP and in Xenopus oocytes after injection of hPBP. As [(35)S]guanosine 5'-3-O-(thio)triphosphate (GTPgammaS) binding to membranes prepared from hPBP-expressing cells was significantly elevated and recombinant hPBP dose-dependently stimulated [(35)S]GTPgammaS binding to native membranes, the results presented provide strong evidence that hPBP-induced effects are G protein-dependent. These data suggest a novel function of hPBP in regulating G protein and G protein-coupled receptor signaling in vivo.

C-terminal splice variants of the mouse mu-opioid receptor differ in morphine-induced internalization and receptor resensitization.

The main analgesic effects of the opioid alkaloid morphine are mediated by the mu-opioid receptor. In contrast to endogenous opioid peptides, morphine activates the mu-opioid receptor without causing its rapid endocytosis. Recently, three novel C-terminal splice variants (MOR1C, MOR1D, and MOR1E) of the mouse mu-opioid receptor (MOR1) have been identified. In the present study, we show that these receptors differ substantially in their agonist-selective membrane trafficking. MOR1 and MOR1C stably expressed in human embryonic kidney 293 cells exhibited phosphorylation, internalization, and down-regulation in the presence of the opioid peptide [d-Ala(2),Me-Phe(4),Gly(5)-ol]enkephalin (DAMGO) but not in response to morphine. In contrast, MOR1D and MOR1E exhibited robust phosphorylation, internalization, and down-regulation in response to both DAMGO and morphine. DAMGO elicited a similar desensitization (during an 8-h exposure) and resensitization (during a 50-min drug-free interval) of all four mu-receptor splice variants. After morphine treatment, however, MOR1 and MOR1C showed a faster desensitization and no resensitization as compared with MOR1D and MOR1E. These results strongly reinforce the hypothesis that receptor phosphorylation and internalization are required for opioid receptor reactivation thus counteracting agonist-induced desensitization. Our findings also suggest a mechanism by which cell- and tissue-specific C-terminal splicing of the mu-opioid receptor may significantly modulate the development of tolerance to the various effects of morphine.

L-selectin and leukocyte function in skeletal muscle reperfusion injury.

HYPOTHESIS: Treatment with anti-L-selectin monoclonal antibody will reduce venular neutrophil-endothelial rolling (flux and velocity) and adhesion associated with ischemia reperfusion injury in rat skeletal muscle. DESIGN: Prospective, randomized experimental trials. SETTING: Basic science research laboratory. MATERIALS: Male Wistar rats weighing 109 +/- 5 g (mean +/- SEM). INTERVENTIONS: Gracilis pedicle muscle flaps were elevated and microcirculation was observed by intravital microscopy. Two groups were evaluated: (1) the control group, which received 4 hours of global ischemia, and (2) the experimental group, which received 4 hours of global ischemia, plus treatment with anti-L-selectin monoclonal antibody 30 minutes before reperfusion. MAIN OUTCOME MEASURES: The number of rolling and adherent leukocytes in postcapillary venules were counted in the 2 groups at baseline and at 1 through 5, 10, 15, 20, 30, 45, and 60 minutes of reperfusion. RESULTS: Treatment with the monoclonal antibody to L-selectin significantly reduced the number of rolling leukocytes (flux) at 2 through 5, 20, 30, 45, and 60 minutes of reperfusion compared with controls (P<.05). Use of the monoclonal antibody significantly reduced the number of adherent neutrophils at 5, 10, 15, 20, 30, 45, and 60 minutes of reperfusion (P<.05). There was no significant difference in leukocyte velocity. CONCLUSION: L-Selectin plays a significant role in leukocyte rolling and adherence to venular endothelium in rat skeletal muscle ischemia reperfusion injury.

Root reinforcement with a resin-bonded preformed post.

PURPOSE: This study evaluated the ability of resin-bonded posts to reinforce teeth that are structurally weak in the cervical area against fracture. MATERIAL AND METHODS: Forty canine roots were endodontically treated and randomly distributed into four groups of 10. Parallel-sided preformed posts were cemented into the roots of these teeth after their crowns were removed. The cervical third of the canals were flared to simulate teeth weakened in this area as a result of caries or endodontic therapy. Three resin cements and a zine-phosphate cement, which was used as the control, were used to secure the posts into the roots. Cemented posts were loaded in an Instron testing machine with a gradually increasing force at a 60-degree angle to the long axis of the root until the root fractured. RESULTS: Roots in which the posts were cemented with Panavia were significantly more resistant to fracture than those where zinc phosphate was used (p < 0.05). Because of the inability to determine exactly the point of failure of the zinc-phosphate cement, no statistically significant difference was found when compared with the other two resin cements (ANOVA and Student-Newman-Keuls test).

Luminal cholecystokinin and gastrin cause gallbladder contraction.

Cholecystokinin-8 placed in the gallbladder lumen causes gallbladder contraction by a neurally mediated, tetrodotoxin-sensitive mechanism. We wished to determine whether other cholecystokinin-like peptides in the gallbladder lumen cause contraction and whether this response is inhibited by cholecystokinin-receptor antagonists. In this study, we measured gallbladder contraction induced by cholecystokinin-like peptides or by hepatic bile placed in the gallbladder lumen. Isolated gallbladders were suspended in an organ bath while luminal hormones were infused. Gallbladder contraction was measured by continuous monitoring of luminal pressure. Cholecystokinin-8, cholecystokinin-5, and gastrin-17 caused dose-related gallbladder contraction with similar potency when placed in the lumen. Each stimulated 70-80% maximal contraction at a luminal concentration of 10(-6) M. Cholecystokinin-receptor antagonists CR1409 and loxiglumide partially inhibited contraction caused by luminal cholecystokinin-8. Bile from fed animals, but not from fasted animals, stimulated gallbladder contraction to 36 +/- 4% of maximal when placed in the gallbladder lumen. We conclude that cholecystokinin and gastrin peptides in the gallbladder lumen cause contraction. This may be mediated through receptors of the cholecystokinin-B type, possibly on intrinsic nerves. Bile from fed animals also contains substances that stimulate gallbladder contraction when bile is placed in the gallbladder lumen. These findings suggest intrinsic nerves participate in the postprandial gallbladder response to cholecystokinin.

Radioactive choline metabolism in guinea pig gallbladder. Is there measurable acetylcholine release?

Acetylcholine may be released from gallbladder intrinsic nerves in response to cholecystokinin stimulation. This study characterized metabolites of [14C]choline produced in the gallbladder and released during incubation, with or without cholecystokinin-octapeptide. Radiolabeled [14C]choline was applied to the mucosal or muscle surface of intact guinea pig gallbladders in an organ bath. After radiolabeling, gallbladders were incubated with or without the contractile agonist cholecystokinin-octapeptide. Metabolites of [14C]choline were identified in gallbladder tissue and incubation buffers using HPLC and thin-layer chromatography. The major metabolites of [14C]choline were betaine and phosphocholine. [14C]Phosphocholine was incorporated slowly into [14C]phosphatidylcholine. [14C]Choline was released into buffers during incubation. [14C]Acetylcholine constituted less than 1% of radiolabel in the gallbladder. There was no identifiable [14C]acetylcholine released in buffers. Cholecystokinin-octapeptide did not affect choline metabolism. These studies showed that choline in the gallbladder is metabolized along pathways similar to those in the liver. Gallbladders released mostly choline, rather than acetylcholine, even during hormonally induced contraction.