bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spinal Adenosine Receptor Activation Reduces Hypersensitivity after Surgery by a Different Mechanism Than after Nerve Injury
Authors: Obata Hideaki , Li Xinhui , Eisenach James C. 
Published: April 2004

Background
Intrathecal adenosine has antinociceptive effects under conditions of hypersensitivity. T62 (2-amino-3-(4-chlorobenzoyl)-5,6,7,8-tetrahydrobenzothiophen) is an allosteric adenosine receptor modulator that enhances adenosine binding to the A1 receptor. Intrathecal T62 reduces hypersensitivity to mechanical stimuli in a rat model of neuropathic pain by a circuit that totally relies on activation of alpha2 adrenoceptors. Here, the authors tested whether this same dependence was present in the acute setting of hypersensitivity after surgery.

Methods
Intrathecal catheters were inserted in male Sprague-Dawley rats. An incision of the plantar aspect of the hind paw resulted 24 h later in hypersensitivity, as measured by applying von Frey filaments to the paw. At this time, rats received intrathecal T62, clonidine, or the combination in a blinded, isobolographic design. The effect of the alpha2-adrenoceptor antagonist idazoxan on T62 was also tested.

Results
Intrathecal T62 produced a dose-dependent antihypersensitivity effect, with no effect on ambulation or activity level. Clonidine also produced a dose-dependent antihypersensitivity effect. The ED40 (95% confidence interval) for T62 was 0.77 (0.63-0.91) microg, and that for clonidine was 1.23 (0.56-1.9) microg. Isobolographic analysis indicated synergism between T62 and clonidine. Intrathecal pretreatment with idazoxan only partially inhibited the antihypersensitivity effect of T62.

Conclusions
Intrathecal T62 is effective for postoperative hypersensitivity. The synergy of T62 with clonidine and its only partial antagonism by idazoxan suggest that T62 does not rely entirely on activation of alpha2 adrenoceptors. These results indicate that, after surgery, T62 acts via a mechanism different from that of spinal nerve ligation, a model of chronic neuropathic pain.
Queuing Theory Accurately Models the Need for Critical Care Resources
Authors: McManus Michael L. , Long Michael C. , Cooper Abbot , Litvak Eugene 
Published: April 2004

Background
Allocation of scarce resources presents an increasing challenge to hospital administrators and health policy makers. Intensive care units can present bottlenecks within busy hospitals, but their expansion is costly and difficult to gauge. Although mathematical tools have been suggested for determining the proper number of intensive care beds necessary to serve a given demand, the performance of such models has not been prospectively evaluated over significant periods.

Methods
The authors prospectively collected 2 years' admission, discharge, and turn-away data in a busy, urban intensive care unit. Using queuing theory, they then constructed a mathematical model of patient flow, compared predictions from the model to observed performance of the unit, and explored the sensitivity of the model to changes in unit size.

Results
The queuing model proved to be very accurate, with predicted admission turn-away rates correlating highly with those actually observed (correlation coefficient = 0.89). The model was useful in predicting both monthly responsiveness to changing demand (mean monthly difference between observed and predicted values, 0.4+/-2.3%; range, 0-13%) and the overall 2-yr turn-away rate for the unit (21%vs. 22%). Both in practice and in simulation, turn-away rates increased exponentially when utilization exceeded 80-85%. Sensitivity analysis using the model revealed rapid and severe degradation of system performance with even the small changes in bed availability that might result from sudden staffing shortages or admission of patients with very long stays.

Conclusions
The stochastic nature of patient flow may falsely lead health planners to underestimate resource needs in busy intensive care units. Although the nature of arrivals for intensive care deserves further study, when demand is random, queuing theory provides an accurate means of determining the appropriate supply of beds.
Hemoglobin Einstein: Semisynthetic deletion in the B‐helix of the α‐chain
Authors: Srinivasulu Sonati , Manjula Belur N. , Nagel Ronald L. , Tsai Ching‐Hsuan , Ho Chien , Prabhakaran Muthuchidambaran , Acharya Seetharama A. 
Published: April 2004

AbstractThe influence of the deletion of the tetra peptide segment α23–26 of the B‐helix of the α‐chain of hemoglobin‐A on its assembly, structure, and functional properties has been investigated. The hemoglobin with the deletion, ss‐Hemoglobin‐Einstein, is readily assembled from semisynthetic α1–141 des23–26 globin and human βA‐chain. The deletion of α23–26 modulates the O2 affinity of hemoglobin in a buffer/allosteric effector specific fashion, but has little influence on the Bohr effect. The deletion has no influence on the thermodynamic stability of the α1β1 and the α1β2 interface. The semisynthetic hemoglobin exhibits normal intersubunit interactions at the α1β1 and α1β2 interfaces as reflected by 1H‐NMR spectroscopy. Molecular modeling studies of ss‐Hemoglobin‐Einstein suggest that the segment α28–35 is in a helical conformation, while the segment α19–22 is the nonhelical AB region. The shortened B‐helix conserves the interactions of α1β1 interface. The results demonstrate a high degree of plasticity in the hemoglobin structure that accommodates the deletion of α23–26 without perturbing its overall global conformation.
Lipoprotein-Associated Phosphatidylethanol Increases the Plasma Concentration of Vascular Endothelial Growth Factor
Authors: Liisanantti Marja K. , Hannuksela Minna L. , Rämet Maria E. , Savolainen Markku J. 
Published: April 2004

Objective—To study whether qualitative changes in high-density lipoprotein (HDL) phospholipids mediate part of the beneficial effects of alcohol on atherosclerosis, we investigated whether phosphatidylethanol (PEth) in HDL particles affects the secretion of vascular endothelial growth factor (VEGF) from endothelial cells.Methods and Results—PEth increased the secretion of VEGF into the culture medium of EA.hy 926 endothelial cells. The mitogen-activated protein kinase (MAPK) phosphorylation increased by 3.3-fold and protein kinase C (PKC) by 2.2-fold by PEth-containing HDL. Moreover, we showed that intravenous injection of PEth incorporated into HDL particles increased plasma concentration of VEGF by 2.4-fold in rats in vivo. Similar effect was observed when the rats were injected with HDL particles isolated from alcohol drinkers.Conclusions—HDL particles containing PEth affect endothelial cells by MAPK and PKC signaling. This may mediate the effects of ethanol on the arterial wall by increasing VEGF secretion from endothelial vascular cells. That may explain, at least in part, the beneficial effect of moderate alcohol consumption on atherosclerosis.
Temperature along the Axillary Nerve during Radiofrequency-Induced Thermal Capsular Shrinkage
Authors: McCarty Eric C. , Warren Russell F. , Deng Xiang-Hu , Craig Edward V. , Potter Hollis 
Published: April 2004

Background There have been reports of axillary nerve palsy after thermal capsular shrinkage with radiofrequency energy-generating devices. The exact cause of this is unknown. Hypothesis The temperature of the axillary nerve increases during shoulder capsular shrinkage at various degrees of shoulder abduction. Study Design Laboratory study. Methods Fifteen cadaveric shoulders had fiberoptic thermometer probes placed at various points along the axillary nerve and major branches under the capsule. The shoulders underwent thermal capsular shrinkage with a radiofrequency energy-inducing device at various positions of abduction. Results With the arm at the side, temperatures above 50°C (56°-61°C) were evident along the teres minor branch of the axillary nerve in 4 of 6 specimens. The increase in temperature was noted in the middle to posterior aspect of the inferior capsule. At 45° of abduction, 4 of 5 shoulders demonstrated increases in temperature greater or equal to 50°. Three of 4 shoulders tested at 90° of abduction revealed similar temperature increases. Conclusions The arthroscopic technique of thermal capsular shrinkage causes an increase in the temperature of the axillary nerve and its branches in 11 of 15 cadaveric specimens tested at various arm positions—particularly affected is the teres minor branch. Clinical Relevance Orthopaedic surgeons using the radiofrequency device for thermal capsular shrinkage need to be aware of the possible increase in temperature along the axillary nerve and its branches during this procedure. The clinical effect of this type of increase on the nerve is unknown.
“All-Inside” Meniscal Repair Devices
Authors: Miller Mark D. , Kline Alex J. , Jepsen Kerry G. 
Published: April 2004

Background Although the use of “all-inside” absorbable meniscal repair devices has become popular, numerous complications have been reported. The authors applied their well-established goat model to evaluate three “all-inside” meniscal repair devices. Methods A “tear” was created in the medial meniscus of both knees in 26 goats. The animals were randomized into four groups, and the meniscus was treated as follows: (A) meniscal repair with Mitek Fastner, (B) meniscal repair with BioStinger, (C) meniscal repair with Mitek Clearfix Screw, and (D) no repair. All animals were sacrificed at 6 months postoperatively, and all specimens were carefully evaluated and results recorded and compared with historical results of meniscal repair with suture in this same animal model. Results Meniscal repair results with all three all-inside devices studied were inferior to suture repair. Chondral injury was present in 75% to 100% of repairs with all-inside devices and none of the control specimens. Discussion/Conclusion Although new all-inside meniscal repair devices are relatively quick and easy, results may not be as good as with traditional suture techniques. The high rate of chondral injury associated with these devices in the goat model is worrisome for chondral damage in humans, especially in patients with smaller or tighter knees.
Initial Fixation Strength of Flexible All-Inside Meniscus Suture Anchors in Comparison to Conventional Suture Technique and Rigid Anchors
Authors: Zantop Thore , Eggers Ann Katleen , Weimann Andre , Hassenpflug Joachim , Petersen Wolf 
Published: April 2004

Background The newest generation of meniscus repair devices is designed to combine the benefits of the all-inside technique with the biomechanical properties of sutures. Hypothesis New flexible all-inside suture anchors have better fixation strength than rigid anchors, but there is no difference when compared to conventional horizontal and vertical mattress sutures. Study Design Controlled laboratory study. Methods In fresh-frozen bovine menisci, initial fixation strength, stiffness, and failure mode of different meniscus fixation techniques (FastT-Fix, RapidLoc, Meniscus Arrow, horizontal and vertical 2.0 Ethibond sutures) were evaluated in a computer-based materials testing machine at a rate of 12.5 mm/sec. Results The vertical and horizontal FastT-Fix suture anchors were the strongest devices with regard to pullout strength, with no significant difference compared to the vertical 2-0 Ethibond sutures. Horizontal sutures, Meniscus Arrow, and RapidLoc had significantly lower pullout strength. Vertical and horizontal FastT-Fix suture anchors showed significantly higher stiffness than the other devices. Conclusions Biomechanical properties of flexible all-inside meniscus anchors (FastT-Fix) are comparable to conventional vertical suture techniques. Characteristics of the flexible RapidLoc are comparable to rigid anchors (Meniscus Arrow). Clinical Relevance From the biomechanical point of view, flexible all-inside meniscus refixation devices are an alternative to conventional suture techniques and rigid meniscus anchors.
The Effect of Growth Factors on Biomechanical Properties of the Bone-Patellar Tendon-Bone Graft after Anterior Cruciate Ligament Reconstruction
Authors: Yasuda Kazunori , Tomita Fumihisa , Yamazaki Shuji , Minami Akio , Tohyama Harukazu 
Published: April 2004

Background No studies have dealt with the effect of growth factors on the free tendon autograft in anterior cruciate ligament reconstruction. Hypothesis Application of exogenous transforming growth factor-β and epidermal growth factor may affect the structural properties and histology of the bone-patellar tendon-bone autograft after anterior cruciate ligament reconstruction. Study Design Controlled laboratory study. Methods Twenty dogs underwent anterior cruciate ligament reconstruction with the autogenous bone-patellar tendon-bone graft in bilateral knees. In 10 animals, 12 ng transforming growth factor-β and 300 ng epidermal growth factor mixed with fibrin sealant of 0.6 mL were applied to the left knee. In the remaining 10 dogs, fibrin sealant alone was applied to the left knee. No additional treatments were applied to the right knee. Results The growth factor application increased the stiffness and maximum failure load of the femur-graft-tibia complex at 12 weeks (P = .016 and P = .012, respectively); the sham treatment did not significantly affect them. Histologically, most of the cells in the grafts treated with growth factors had spindle-shaped nuclei; cells in the other grafts had round-shaped nuclei. Conclusions Application of transforming growth factor-β and epidermal growth factor improves the structural properties of the autograft after anterior cruciate ligament reconstruction in the canine model. Clinical Relevance Application of growth factors is a possible strategy to prevent graft deterioration in anterior cruciate ligament reconstruction.
Contact Pressure at Osteochondral Donor Sites in the Patellofemoral Joint
Authors: Garretson Ralph B. , Katolik Leonid I. , Verma Nikhil , Beck Paul R. , Bach Bernard R. , Cole Brian J. 
Published: April 2004

Background The lowest contact pressure point is presumed to be the best site to harvest an osteochondral plug and minimize morbidity. Hypothesis Patellofemoral contact pressures are not uniform and are lowest along the medial patellofemoral articulation. Study Design Controlled laboratory study. Methods Seven cadaveric knees were tested with an electroresistive, dynamic pressure sensor placed onto the femoral side of the patellofemoral joint. The extensor mechanism was loaded with 89.1 N and 178.2 N, and the knee was manually cycled 3 times (0°-105°) per load. Mean trochlear pressures were calculated. Results Mean contact pressures were greatest in the central trochlea (5.80 kgf/cm2), followed by the lateral (2.56 kgf/cm2) and medial trochlea (1.60 kgf/cm2) at 89.1 N (P < .05). At 178.2 N, pressures increased to 9.47, 5.81, and 2.75 kgf/cm2, respectively (P < .05). Lateral trochlear pressures decreased moving distally from 1.25 to 0.50 kgf/cm2 at 89.1 N and 4.57 to 1.29 kgf/cm2 at 178.2 N. Conclusions Contact pressures are lowest along the medial trochlea and decrease distally along the lateral trochlea. Clinical Relevance Osteochondral plugs from the medial femoral trochlea may be desirable if trochlear size permits. If harvesting from the lateral femoral trochlea, consider harvesting distally near the sulcus terminalis.
Abnormal Rotational Knee Motion during Running after Anterior Cruciate Ligament Reconstruction
Authors: Tashman Scott , Collon David , Anderson Kyle , Kolowich Patricia , Anderst William 
Published: April 2004

Background The effectiveness of anterior cruciate ligament reconstruction for restoring normal knee kinematics is largely unknown, particularly during sports movements generating large, rapidly applied forces. Hypothesis Under dynamic in vivo loading, significant differences in 3-dimensional kinematics exist between anterior cruciate ligament-reconstructed knees and the contralateral, uninjured knees. Study Design Prospective, in vivo laboratory study. Methods Kinematics of anterior cruciate ligament-reconstructed and contralateral (uninjured) knees were evaluated for 6 subjects during downhill running 4 to 12 months after anterior cruciate ligament reconstruction, using a 250 frame/s stereoradiographic system. Anatomical reference axes were determined from computed tomography scans. Kinematic differences between the uninjured and reconstructed limbs were evaluated with a repeated-measures analysis of variance. Results Anterior tibial translation was similar for the reconstructed and uninjured limbs. However, reconstructed knees were more externally rotated on average by 3.8 ± 2.3° across all subjects and time points (P = .0011). Reconstructed knees were also more adducted, by an average of 2.8 ± 1.6° (P = .0091). Although differences were small, they were consistent in all subjects. Conclusions Anterior cruciate ligament reconstruction failed to restore normal rotational knee kinematics during dynamic loading. Clinical Relevance Although further study is required, these abnormal motions may contribute to long-term joint degeneration associated with anterior cruciate ligament injury/reconstruction.
The Influence of Locally Applied Platelet-Derived Growth Factor-BB on Free Tendon Graft Remodeling after Anterior Cruciate Ligament Reconstruction
Authors: Weiler Andreas , Förster Cornelius , Hunt Patrick , Falk Roman , Jung Tobias , Unterhauser Frank N. , Bergmann Volker , Schmidmaier Gerhard , Haas Norbert P. 
Published: April 2004

Background Ligaments and tendons do not gain mechanical properties of the native tissue after injury or grafting. Purpose To determine the influence of platelet-derived growth factor on tendon graft remodeling. Study Design Laboratory animal study. Methods Forty-eight sheep underwent anterior cruciate ligament reconstruction and were sacrificed after 3, 6, 12, and 24 weeks. In 6 animals at each time point, platelet-derived growth factor was locally delivered via coated sutures. After mechanical testing, tissue samples were taken for histologic, immunohistochemical, and electron microscopy evaluations. Results With platelet-derived growth factor treatment, cross-sectional area was significantly lower at 3 and 12 weeks. Load to failure was significantly higher at 6 weeks. Tensile stress was significantly higher at 3 and 12 weeks. Crimp length was significantly higher at 3 and 6 weeks. Vascular density was significantly higher at 6 weeks. Electron microscopy showed a significantly higher collagen fibril amount at 12 weeks. Differences in these parameters at other time points were not significant. Conclusions There were alterations in several but not all time points. The local application of platelet-derived growth factor alters the tissue's mechanical properties during free tendon graft remodeling after anterior cruciate ligament reconstruction. Growth factors present a promising tool toward the complete mechanical restitution of a healing ligament substitute.
Injury Mechanisms for Anterior Cruciate Ligament Injuries in Team Handball
Authors: Olsen Odd-Egil , Myklebust Grethe , Engebretsen Lars , Bahr Roald 
Published: April 2004

Objective To describe the mechanisms for anterior cruciate ligament injuries in female team handball. Study Design Descriptive video analysis. Methods Twenty videotapes of anterior cruciate ligament injuries from Norwegian or international competition were collected from 12 seasons (1988-2000). Three medical doctors and 3 national team coaches systematically analyzed these videos to describe the injury mechanisms and playing situations. In addition, 32 anterior cruciate ligament-injured players in the 3 upper divisions in Norwegian team handball were interviewed during the 1998-1999 season to compare the injury characteristics between player recall and the video analysis. Results Two main injury mechanisms for anterior cruciate ligament injuries in team handball were identified. The most common (12 of 20 injuries), a plant-and-cut movement, occurred in every case with a forceful valgus and external or internal rotation with the knee close to full extension. The other main injury mechanism (4 of 20 injuries), a 1-legged jump shot landing, occurred with a forceful valgus and external rotation with the knee close to full extension. The results from the video analysis and questionnaire data were similar. Conclusions The injury mechanism for anterior cruciate ligament injuries in female team handball appeared to be a forceful valgus collapse with the knee close to full extension combined with external or internal rotation of the tibia.
The Effect of Length on the Structural Properties of an Achilles Tendon Graft as Used in Posterior Cruciate Ligament Reconstruction
Authors: DeFrate Louis E. , van der Ven Alexander , Gill Thomas J. , Li Guoan 
Published: April 2004

Background The clinical outcomes of posterior cruciate ligament reconstruction are varied. No previous studies have investigated the effect of graft length on the structural properties of the graft. Hypothesis Graft length significantly affects the structural properties of posterior cruciate ligament grafts. Study Design Controlled laboratory study. Methods Eight Achilles tendon grafts were tested under tensile loads up to 400 N at 3 different lengths: long (75 mm), medium (48 mm), and short (34 mm). These 3 lengths represent midtunnel fixation, inlay fixation, and fixation near the ligament insertions. Results Shortening the graft from both long to medium and from medium to short increased the stiffness by approximately 25%. Long and medium grafts displaced significantly more than medium and short grafts, respectively. Conclusion The effective length of a graft, which is determined by where it is fixed, should be considered an important variable in posterior cruciate ligament reconstruction.
Reflexive Muscle Activation Alterations in Shoulders with Anterior Glenohumeral Instability
Authors: Myers Joseph B. , Ju Yan-Ying , Hwang Ji-Hye , McMahon Patrick J. , Rodosky Mark W. , Lephart Scott M. 
Published: April 2004

Background Patients with glenohumeral instability have proprioceptive deficits that are suggested to contribute to muscle activation alterations. Hypothesis Muscle activation alterations will be present in shoulders with anterior glenohumeral instability. Study Design Posttest-only control group design. Methods Eleven patients diagnosed with anterior glenohumeral instability were matched with 11 control subjects. Each subject received an external humeral rotation apprehension perturbation while reflexive muscle activation characteristics were measured with indwelling electromyography and surface electromyography. Results Patients with instability demonstrated suppressed pectoralis major and biceps brachii mean activation; increased peak activation of the subscapularis, supraspinatus, and infraspinatus; and a significantly slower biceps brachii reflex latency. Supraspinatus-subscapularis coactivation was significantly suppressed in the patients with instability as well. Conclusions and Clinical Relevance In addition to the capsuloligamentous deficiency and proprioceptive deficits present in anterior glenohumeral instability, muscle activation alterations are also present. The suppressed rotator cuff coactivation, slower biceps brachii activation, and decreased pectoralis major and biceps brachii mean activation may contribute to the recurrent instability episodes seen in this patient group. Clinicians can implement therapeutic exercises that address the suppressed muscles in patients opting for conservative management or rehabilitation before and after capsulorraphy procedures.