Deep Learning Assistance Closes the Accuracy Gap in Fracture Detection Across Clinician Types

BACKGROUND

Missed fractures are the most common diagnostic errors in musculoskeletal imaging and can result in treatment delays and preventable morbidity. Deep learning, a subfield of artificial intelligence, can be used to accurately detect fractures by training algorithms to emulate the judgments of expert clinicians. Deep learning systems that detect fractures are often limited to specific anatomic regions and require regulatory approval to be used in practice. Once these hurdles are overcome, deep learning systems have the potential to improve clinician diagnostic accuracy and patient care.

QUESTIONS/PURPOSES

This study aimed to evaluate whether a Food and Drug Administration-cleared deep learning system that identifies fractures in adult musculoskeletal radiographs would improve diagnostic accuracy for fracture detection across different types of clinicians. Specifically, this study asked: (1) What are the trends in musculoskeletal radiograph interpretation by different clinician types in the publicly available Medicare claims data? (2) Does the deep learning system improve clinician accuracy in diagnosing fractures on radiographs and, if so, is there a greater benefit for clinicians with limited training in musculoskeletal imaging?

METHODS

We used the publicly available Medicare Part B Physician/Supplier Procedure Summary data provided by the Centers for Medicare & Medicaid Services to determine the trends in musculoskeletal radiograph interpretation by clinician type. In addition, we conducted a multiple-reader, multiple-case study to assess whether clinician accuracy in diagnosing fractures on radiographs was superior when aided by the deep learning system compared with when unaided. Twenty-four clinicians (radiologists, orthopaedic surgeons, physician assistants, primary care physicians, and emergency medicine physicians) with a median (range) of 16 years (2 to 37) of experience postresidency each assessed 175 unique musculoskeletal radiographic cases under aided and unaided conditions (4200 total case-physician pairs per condition). These cases were comprised of radiographs from 12 different anatomic regions (ankle, clavicle, elbow, femur, forearm, hip, humerus, knee, pelvis, shoulder, tibia and fibula, and wrist) and were randomly selected from 12 hospitals and healthcare centers. The gold standard for fracture diagnosis was the majority opinion of three US board-certified orthopaedic surgeons or radiologists who independently interpreted the case. The clinicians' diagnostic accuracy was determined by the area under the curve (AUC) of the receiver operating characteristic (ROC) curve, sensitivity, and specificity. Secondary analyses evaluated the fracture miss rate (1-sensitivity) by clinicians with and without extensive training in musculoskeletal imaging.

RESULTS

Medicare claims data revealed that physician assistants showed the greatest increase in interpretation of musculoskeletal radiographs within the analyzed time period (2012 to 2018), although clinicians with extensive training in imaging (radiologists and orthopaedic surgeons) still interpreted the majority of the musculoskeletal radiographs. Clinicians aided by the deep learning system had higher accuracy diagnosing fractures in radiographs compared with when unaided (unaided AUC: 0.90 [95% CI 0.89 to 0.92]; aided AUC: 0.94 [95% CI 0.93 to 0.95]; difference in least square mean per the Dorfman, Berbaum, Metz model AUC: 0.04 [95% CI 0.01 to 0.07]; p < 0.01). Clinician sensitivity increased when aided compared with when unaided (aided: 90% [95% CI 88% to 92%]; unaided: 82% [95% CI 79% to 84%]), and specificity increased when aided compared with when unaided (aided: 92% [95% CI 91% to 93%]; unaided: 89% [95% CI 88% to 90%]). Clinicians with limited training in musculoskeletal imaging missed a higher percentage of fractures when unaided compared with radiologists (miss rate for clinicians with limited imaging training: 20% [95% CI 17% to 24%]; miss rate for radiologists: 14% [95% CI 9% to 19%]). However, when assisted by the deep learning system, clinicians with limited training in musculoskeletal imaging reduced their fracture miss rate, resulting in a similar miss rate to radiologists (miss rate for clinicians with limited imaging training: 9% [95% CI 7% to 12%]; miss rate for radiologists: 10% [95% CI 6% to 15%]).

CONCLUSION

Clinicians were more accurate at diagnosing fractures when aided by the deep learning system, particularly those clinicians with limited training in musculoskeletal image interpretation. Reducing the number of missed fractures may allow for improved patient care and increased patient mobility.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Optical Mammography in Patients with Breast Cancer Undergoing Neoadjuvant Chemotherapy: Individual Clinical Response Index

RATIONALE AND OBJECTIVES

We present an optical mammography study that aims to develop quantitative measures of pathologic response to neoadjuvant chemotherapy (NAC) in patients with breast cancer. Such quantitative measures are based on the concentrations of oxyhemoglobin ([HbO₂]), deoxyhemoglobin ([Hb]), total hemoglobin ([HbT]), and hemoglobin saturation (SO₂) in breast tissue at the tumor location and at sequential time points during chemotherapy.

MATERIALS AND METHODS

Continuous-wave, spectrally resolved optical mammography was performed in transmission and parallel-plate geometry on 10 patients before treatment initiation and at each NAC administration (mean number of optical mammography sessions: 12, range: 7-18). Data on two patients were discarded for technical reasons. The patients were categorized as responders (R, >50% decrease in tumor size), or nonresponders (NR, <50% decrease in tumor size) based on imaging and histopathology results.

RESULTS

At 50% completion of the NAC regimen (therapy midpoint), R (6/8) demonstrated significant decreases in SO₂ (-27% ± 4%) and [HbT] (-35 ± 4 µM) at the tumor location with respect to baseline values. By contrast, NR (2/8) showed nonsignificant changes in SO₂ and [HbT] at therapy midpoint. We introduce a cumulative response index as a quantitative measure of the individual patient's response to therapy. At therapy midpoint, the SO₂-based cumulative response index had a sensitivity of 100% and a specificity of 100% for the identification of R.

CONCLUSIONS

These results show that optical mammography is a promising tool to assess individual response to NAC at therapy midpoint to guide further decision making for neoadjuvant therapy.

Optical mammography: bilateral breast symmetry in hemoglobin saturation maps

We present a study of the bilateral symmetry of human breast hemoglobin saturation maps measured with a broadband optical mammography instrument. We have imaged 21 patients with unilateral breast cancer, 32 patients with unilateral benign lesions, and 27 healthy patients. An image registration process was applied to the bilateral hemoglobin saturation (SO 2 SO2 ) images by assigning each pixel to the low, middle, or high range of SO 2 SO2 values, where the thresholds for the categories were the 15th and 85th percentiles of the individual saturation range. The Dice coefficient, which is a measure of similarity, was calculated for each patient’s pair of right and left breast SO 2 SO2 images. The invasive cancer patients were found to have an average Dice coefficient value of 0.55±0.07 0.55±0.07 , which was significantly lower than the benign and healthy groups (0.61±0.11 0.61±0.11 and 0.62±0.12 0.62±0.12 , respectively). Although differences were seen in a group analysis, the healthy patient Dice coefficients spanned a wide range, limiting the diagnostic capabilities of this SO 2 SO2 symmetry analysis on an individual basis. Our results suggest that for assessing the SO 2 SO2 contrast of breast lesions, it may be better to select a reference tissue in the ipsilateral rather than the contralateral breast.

Broadband optical mammography instrument for depth-resolved imaging and local dynamic measurements

We present a continuous-wave instrument for non-invasive diffuse optical imaging of the breast in a parallel-plate transmission geometry. The instrument measures continuous spectra in the wavelength range 650-1000 nm, with an intensity noise level <1.5% and a spatial sampling rate of 5 points/cm in the x- and y-directions. We collect the optical transmission at four locations, one collinear and three offset with respect to the illumination optical fiber, to recover the depth of optical inhomogeneities in the tissue. We imaged a tissue-like, breast shaped, silicone phantom (6 cm thick) with two embedded absorbing structures: a black circle (1.7 cm in diameter) and a black stripe (3 mm wide), designed to mimic a tumor and a blood vessel, respectively. The use of a spatially multiplexed detection scheme allows for the generation of on-axis and off-axis projection images simultaneously, as opposed to requiring multiple scans, thus decreasing scan-time and motion artifacts. This technique localizes detected inhomogeneities in 3D and accurately assigns their depth to within 1 mm in the ideal conditions of otherwise homogeneous tissue-like phantoms. We also measured induced hemodynamic changes in the breast of a healthy human subject at a selected location (no scanning). We applied a cyclic, arterial blood pressure perturbation by alternating inflation (to a pressure of 200 mmHg) and deflation of a pneumatic cuff around the subject's thigh at a frequency of 0.05 Hz, and measured oscillations with amplitudes up to 1 μM and 0.2 μM in the tissue concentrations of oxyhemoglobin and deoxyhemoglobin, respectively. These hemodynamic oscillations provide information about the vascular structure and functional integrity in tissue, and may be used to assess healthy or abnormal perfusion in a clinical setting.

The self-aligning knee prosthesis: clinical and radiological outcome and survival analysis of a cruciate retaining meniscal bearing knee at 10-year follow-up

PURPOSE

Previously, the clinical and radiological results of the self-aligning cruciate retaining total knee prosthesis at 5-years follow-up were described. The 10-year follow-up is now reported to determine the clinical and radiological results and the survival of the prosthesis.

METHODS

A 10-year follow-up was performed in this prospectively followed cohort of 246 (232 patients) self-aligning, cruciate retaining total knee arthroplasties performed between 1995 and 1998. Because patients had died and others suffered from comorbidities making them unable to attend a follow-up consultation, data could be obtained for 105 prostheses. Clinical results were evaluated by the Knee Society Score, and radiological follow-up was performed on standard AP and lateral X-rays. All radiographs were evaluated for the presence of radiolucencies, osteolysis and wear.

RESULTS

At the 10-year follow-up, there were no new cases of revision so that the cumulative survival rate at 10 years remains 95%. The 10-year follow-up shows good clinical results with an average Knee Society Score of 154 (SD 35.7) and an average range of motion of 109° (SD 13.7). After excluding 25 prostheses for comorbidities, the mean 10-year KSS score increased from 154 to 163 (SD 26.2). On the other hand, for the ROM, the exclusion of the 25 prostheses had no influence on the mean ROM value of 109°. At the 10-year follow-up, none of the 100 available radiographs showed any radiolucencies >2 mm on any component.

CONCLUSIONS

Long-term follow-up of the mobile bearing, cruciate retaining, SAL-II total knee arthroplasty shows excellent clinical and radiological results without bearing dislocation.

LEVEL OF EVIDENCE

Prospective cohort, Level IV.

Do tibiofemoral contact point and posterior condylar offset influence outcome and range of motion in a mobile-bearing total knee arthroplasty?

PURPOSE

The posterior condylar offset (PCO) and the tibiofemoral contact point (CP) have been reported as important factors that can influence range of motion and clinical outcome after total knee arthroplasty. A mobile-bearing knee implant with an anterior posterior gliding insert would in theory be more sensitive for changes in PCO and CP. For this reason, we analysed the PCO and CP and the relation with outcome and range of motion in 132 patients from a prospectively documented cohort in this type of implant.

METHODS

The prosthesis used was a posterior cruciate retaining AP gliding mobile-bearing total knee replacement (SAL II Sulzer Medica, Switzerland). In 132 knees, the pre- and postoperative PCO and postoperative CP were evaluated. Measurements were made on X-rays of the knee taken in approximately 90° of flexion and with less than 3-mm rotation of the femur condyles. The outcome parameters, range of motion (ROM) and the knee society score (KSS), for each knee were determined preoperatively and at 5-year follow-up.

RESULTS

The mean KSS improved from 91 to 161 at 5-year follow-up (p < 0.001) and the mean ROM from 102 to 108 (p < 0.05). The mean PCO difference (postoperative PCO-preoperative PCO) was--0.05 mm (SD 2.15). The CP was on average 53.9% (SD 5.5%). ROM was different between the 3 PCO groups (p = 0.05): patients with 3 or more mm decrease in PCO had the best postoperative ROM (p = 0.047). There was no statistical difference between the postoperative ROM between patients with a stable PCO and those with an increased PCO. There was no correlation between the difference in PCO and the difference in ROM; R Pearson = -0.056. There was no difference in postoperative ROM or postoperative total KSS between CP <60% and CP >60%: p = 0.22, p = 0.99, for ROM and KSS, respectively. Scatter plots showed uniform clouds of values: increase or decrease in PCO and CP had no significant influence on ROM or KSS.

CONCLUSION

The hypotheses that a stable PCO and a more natural CP increase postoperative ROM and improve clinical outcome could not be confirmed. On the contrary, a decreased PCO seemed to improve knee flexion. Furthermore, a relationship between PCO and CP could not be found.

LEVEL OF EVIDENCE

Prospective cohort study, Level II.

Stable fixation of the IBP humeral component implanted without cement in total elbow replacement: a radiostereometric analysis study of 16 elbows at two-year follow-up

We determined the short-term clinical outcome and migration within the bone of the humeral cementless component of the Instrumented Bone Preserving (IBP) total elbow replacement in a series of 16 patients. There were four men and 12 women with a mean age at operation of 63 years (40 to 81). Migration was calculated using radiostereometric analysis. There were no intra-operative complications and no revisions. At two-year follow-up, all patients showed a significant reduction in pain and functional improvement of the elbow (both p < 0.001). Although ten components (63%) showed movement or micromovement during the first six weeks, 14 (88%) were stable at one year post-operatively. Translation was primarily found in the proximal direction (median 0.3 mm (interquartile range (IQR) -0.09 to 0.8); the major rotational movement was an anterior tilt (median 0.7° (IQR 0.4° to 1.6°)). One malaligned component continued to migrate during the second year, and one component could not be followed beyond three months because migration had caused the markers to break off the prosthesis. This study shows promising early results for the cementless humeral component of the IBP total elbow replacement. All patients had a good clinical outcome, and most components stabilised within six months of the operation.

Depth discrimination in diffuse optical transmission imaging by planar scanning off-axis fibers: initial applications to optical mammography

We present a method for depth discrimination in parallel-plate, transmission mode, diffuse optical imaging. The method is based on scanning a set of detector pairs, where the two detectors in each pair are separated by a distance δDi along direction δ D i within the x-y scanning plane. A given optical inhomogeneity appears shifted by αi δ D i (with 0≤ αi ≤1) in the images collected with the two detection fibers of the i-th pair. Such a spatial shift can be translated into a measurement of the depth z of the inhomogeneity, and the depth measurements based on each detector pair are combined into a specially designed weighted average. This depth assessment is demonstrated on tissue-like phantoms for simple inhomogeneities such as straight rods in single-rod or multiple-rod configurations, and for more complex curved structures which mimic blood vessels in the female breast. In these phantom tests, the method has recovered the depth of single inhomogeneities in the central position of the phantom to within 4 mm of their actual value, and within 7 mm for more superficial inhomogeneities, where the thickness of the phantom was 65 mm. The application of this method to more complex images, such as optical mammograms, requires a robust approach to identify corresponding structures in the images collected with the two detectors of a given pair. To this aim, we propose an approach based on the inner product of the skeleton images collected with the two detectors of each pair, and we present an application of this approach to optical in vivo images of the female breast. This depth discrimination method can enhance the spatial information content of 2D projection images of the breast by assessing the depth of detected structures, and by allowing for 3D localization of breast tumors.

Parametric estimation of 3D tubular structures for diffuse optical tomography

We explore the use of diffuse optical tomography (DOT) for the recovery of 3D tubular shapes representing vascular structures in breast tissue. Using a parametric level set method (PaLS) our method incorporates the connectedness of vascular structures in breast tissue to reconstruct shape and absorption values from severely limited data sets. The approach is based on a decomposition of the unknown structure into a series of two dimensional slices. Using a simplified physical model that ignores 3D effects of the complete structure, we develop a novel inter-slice regularization strategy to obtain global regularity. We report on simulated and experimental reconstructions using realistic optical contrasts where our method provides a more accurate estimate compared to an unregularized approach and a pixel based reconstruction.

Ultra sonographic findings for chronic lateral epicondylitis

PURPOSE

To assess which individual gray-scale and color Doppler US findings and their combination are strongly associated with lateral epicondylitis. Also to determine whether chronic lateral epicondylitis is possible without any positive US findings.

METHODS

49 patients (6 bilateral) underwent gray-scale ultrasonic imaging between 2005 to 2007. All had a history of lateral epicondylitis and had concordant pain during US probe compression in the common extensor region. Mean patient age was 47 (sd 7.7) years; M/F ratio 21/28; L/R ratio 17/32. Five symptom free volunteers (all bilateral) with a mean age of 36 (sd 8.7) years; M/F = 4/6; L/R = 5/5.

RESULTS

Neovascularity determined by color Doppler and four gray-scale US findings - a convex external contour, an erosive lateral epicondular cortex, internal calcifications, or a tear - have a specificity and PPV of 100% with conclusive likelihood ratios. However, only the sensitivity for neovascularity is above 50%. A combination of gray-scale and color Doppler shows a sensitivity between 92% to 100%, a 90% specificity with a 98% PPV and a high likelihood ratio (9 to 10).

CONCLUSION

The combination of gray-scale and color Doppler changes is diagnostically superior to identify chronic lateral epicondylitis. Signs which confirm the diagnosis are a convex boundary, an erosive cortex, internal calcifications, a tear, and neovascularity. Patients with positive clinical signs and concordant pain but no US findings require further MRI evaluation.

Effect of graphite concentration on shear-wave speed in gelatin-based tissue-mimicking phantoms

Elasticity-based imaging modalities are becoming popular diagnostic tools in clinical practice. Gelatin-based, tissue mimicking phantoms that contain graphite as the acoustic scattering material are commonly used in testing and validating elasticity-imaging methods to quantify tissue stiffness. The gelatin bloom strength and concentration are used to control phantom stiffness. While it is known that graphite concentration can be modulated to control acoustic attenuation, the impact of graphite concentration on phantom elasticity has not been characterized in these gelatin phantoms. This work investigates the impact of graphite concentration on phantom shear stiffness as characterized by shear-wave speed measurements using impulsive acoustic-radiation-force excitations. Phantom shear-wave speed increased by 0.83 (m/s)/(dB/(cm MHz)) when increasing the attenuation coefficient slope of the phantom material through increasing graphite concentration. Therefore, gelatin-phantom stiffness can be affected by the conventional ways that attenuation is modulated through graphite concentration in these phantoms.

Foot Build Registration System (FBRS) to evaluate foot posture: a reliability study with healthy subjects and patients with Charcot-Marie-Tooth disease

BACKGROUND

To follow the weight bearing foot posture in subjects, a measurement tool using digital photography was developed, Foot Build Registration System (FBRS) (Fig. 1) [M. Van der Cruijsen, Voetvorm registratie systeem, Boxmeer (1999).]. This study's objective was to investigate the reproducibility of FBRS measurements in healthy feet and feet of patients with Charcot-Marie-Tooth disease (CMT).

METHODS

Reproducibility and reliability studies were performed in several foot views in healthy and CMT patients.

RESULTS

These studies showed that the variability of the 95% prediction limit depended upon the foot view being studied and whether markers had been drawn. Some individuals had a higher intra-individual variability than others. Limiting data collection to those individuals with a SD<3.5 degrees for a series of five or more photographs per view improved the 95% prediction limits. These varied between 2.8 degrees and 7.7 degrees.

CONCLUSIONS

If the differences found between registration are greater than the abovementioned, values can be attributed to time or operative management for healthy and CMT patients and not to measurement error.

A modified tibial tubercle osteotomy for patellar maltracking: results at two years

An abnormal lateral position of the tibial tuberosity causes distal malalignment of the extensor mechanism of the knee and can lead to lateral tracking of the patella causing anterior knee pain or objective patellar instability, characterised by recurrent dislocation. Computer tomography is used for a precise pre-operative assessment of the tibial tubercle-trochlear groove distance. A distance of more than 15 mm is considered to be pathological and an indication for surgery in symptomatic patients. In a prospective study we performed a subtle transfer of the tibial tuberosity according to the information gained from the pre-operative CT scan. This method was applied to two groups of patients, those with painful lateral tracking of the patella, and those with objective patellar instability. We evaluated the clinical results in 30 patients in each group. The outcome was documented at 3, 12 and 24 months using the Lysholm scale, the Kujala score, and a visual analogue pain score. Post-operatively, all but one patient in the instability group who had a patellar dislocation requiring further surgery reported good improvement with no further subluxation or dislocation. All patients in both groups had a marked improvement in pain and functional score. Two patients sustained a tibial fracture six and seven weeks after surgery. One patient suffered a per-operative fracture of the tibial tubercle which later required further fixation. If carefully performed, this type of transfer of the tibial tubercle appears to be a satisfactory technique for the treatment of patients with an increased tibial tubercle-trochlear groove distance and who present with symptoms related to lateral maltracking of the patella.

The uncemented, titanium-coated rm cup: Survival and analyses of failures

This study evaluates the incidence of revision of the monoblock, uncemented, titanium-coated RM (Robert Mathys) cup (Mathys Medical, Bettlach, Switzerland) in primary total hip arthroplasty. Between 1991 and 1995 a total of 630 RM cups were implanted in 462 patients. A Kaplan-Meier survival analysis was performed with failure defined as acetabular revision for any reason. The mean follow-up was 8.2 years. A total of 34 acetabular revisions (5%) were carried out: 15 for recurrent dislocation due to cup malposition, nine for wear caused by impingement of a loose femoral component, five for aseptic loosening, only one cup was revised for articular polyethylene wear, and four for other causes. The cumulative survival rate of the RM cup is 91% at 10.7 years, with a worst case scenario of 87%. The cumulative survival rate for aseptic loosening was calculated: 99% at 10.7 years. The titanium-coated RM cup shows an impressive survival rate with revision for aseptic loosening as endpoint. Correct cup positioning is the key to success and requires experience and meticulous surgical technique. (Hip International 2005; 15: 71-7).

The Zweymller cementless total hip prosthesis in patients aged 50 years and younger

Sixty-eight young patients (74 prostheses), mean age 43 years (standard deviation 7.7) at the time of the index operation, with a Zweymller cementless total hip prosthesis were evaluated with a mean follow-up time of 75 months (sd 15.7). At follow-up, the mean Harris Hip Score was 94 (sd 8.1). Six stem prostheses had vertical sub-sidence and nine cups showed signs indicating possible loosening. The Oxford Hip Score averaged 19 points (sd 8.7). Revision surgery was performed for septic loosening (n=3 stem and cup prostheses), for aseptic loosening of the cup (n=2), and for a traumatic periprosthetic fracture (n=1 stem). Worst case survival analysis for aseptic loosening of the cup showed a probability for revision of 3% (CI95 0 7.2%) with a cumulative survival of 96% (CI95 100 90.3%) after 84 months. For the stem prostheses the probability for revision was 1% (CI95 0 4.3%) after 114 months with a cumulative survival of 99% (CI95 100 95.8%) after 72 months. Worst case cumulative survival for any reason of revision was 94.5% (CI95 99.9 89.2%) after 81 months. Promising results of the Zweymller cementless hip prosthesis for the younger patient were obtained, although longer follow-up will be necessary. (Hip International 2005; 15: 1-11).

Single or double-level anterior interbody fusion techniques for cervical degenerative disc disease

BACKGROUND

The number of surgical techniques for decompression and solid interbody fusion as a treatment for cervical spondylosis has increased rapidly, but the rationale for the choice between different techniques is unclear.

OBJECTIVES

The goal of this study was to determine which method of anterior cervical interbody fusion at a single or double-level provides the best clinical and radiological outcome in patients with degenerative disc disease.

SEARCH STRATEGY

Studies were identified with a computer-assisted search of electronic databases in the Cochrane Central Register of Controlled Trials (Issue 1, 2004), MEDLINE (1966 to 2004), EMBASE (1980 to 2004), and Current Contents (1996 to 2004). We also searched references of selected articles.

SELECTION CRITERIA

With the aid of a checklist, two reviewers independently screened the identified references. Consensus was reached through negotiation. A third reviewer was consulted if consensus could not be reached. Inclusion criteria included: articles were reports of randomised comparative studies; treatments compared anterior cervical decompression and interbody fusion techniques, participants were individuals scheduled for surgery for a chronic (longer than 12 weeks) diagnosis of degenerative disc disease.

DATA COLLECTION AND ANALYSIS

Methodological quality was assessed independently by two reviewers, using the van Tulder list of criteria. With the aid of a data extraction form, data was extracted independently by two reviewers on group characteristics, intervention details and outcome measures.

MAIN RESULTS

Fourteen studies with 939 patients evaluated three comparisons of different fusion techniques. From these comparisons it appears that discectomy alone has a shorter operation time, hospital stay, and post-operative absence from work than discectomy with fusion, while there is no statistical difference for pain relief and rate of fusion. It also appears that fusion techniques that use autograft give a better chance for fusion than interbody fusion techniques that use a cage, but other outcome variables could not be combined.

REVIEWERS' CONCLUSIONS

The low quality of the trials prohibits extensive conclusions from this review. More studies with better methodology and reporting are needed. There should be a more general agreement between researchers on which outcome parameters should be used in the evaluation of anterior cervical fusion procedures.

Total hip arthroplasty with Boneloc cement: Unsatisfactory results in 163 hips after 9 to 11 years

Boneloc bone cement was introduced in the Netherlands in 1992. Inferior short-term results were reported which led to the withdrawal of Boneloc from clinical use in 1995. However, little is known about the long-term outcome of hip arthroplasties with Boneloc. Between April 1992 and August 1994, Boneloc was used in 163 Mallory-Head primary total hip arthroplasties in 163 patients. Follow-up analysis was performed in 2003. To date, 27 hips (17%) have been revised for aseptic loosening of the femoral component. Median time to revision was 5.5 years. Survival analysis based on revision for aseptic loosening showed 77% cumulative survival at 11 years. With revision for aseptic loosening and/or definite radiological loosening according to Harris as endpoint, cumulative survival was 59% at 11 years. In 27 of 43 patients with definite radiological loosening, a cement fracture was seen at a median of 2.9 years. These results show failure of Boneloc cemented total hip arthroplasties occurring even during the later follow-up. Continuing periodic clinical and radiological examination is recommended. (Hip International 2004; 14: 229-32).

CT Density Measurement of Bone Graft Within an Intervertebral Lumbar Cage

Radiographic assessment of lumbar interbody fusion is difficult, especially in the presence of cages and metal artifacts. The purpose of this study is to assess whether impacted bone chips in intervertebral lumbar cages show a tendency toward increased attenuation on postoperative computed tomography (CT) scans as a sign of ongoing revascularization and increased bone mineral content inside the cage. Twenty-one patients with single- or double-level lumbar fusion underwent CT scanning 1-44 months postoperatively. CT attenuation of bone inside the cage was measured with Hounsfield units. Intra- and interobserver variability were evaluated. Regression analysis showed an increase of 7.5 HU/month postoperatively for an initial value of 615 HU. Intra- and interobserver variability showed an interclass coefficient of 0.97. CT attenuation of bone graft inside an intervertebral cage increases in the postoperative period. Hounsfield unit measurement can be performed with a high degree of accuracy and reproducibility and may in the future provide a useful tool in studying cage contents in individual patients.

Patients with lateral tracking patella have better pain relief following CT-guided tuberosity transfer than patients with unstable patella

In patients with either lateral tracking patella or unstable patella the pathological lateral position of the tuberosity can be corrected by a medial transfer. This study compared the results of subtle CT-guided correction of the tuberosity for objective unstable patella (n=27) with the results for lateral tracking patella (potential instability) as described by Dejour (n=16). Follow-up was 37 months. CT revealed a pathological lateralization of the tibial tuberosity-trochlear groove greater than 15 mm in 41 knees. These patients underwent medialization of the tibial tuberosity up to 10-12 mm lateral from the trochlear groove, and 28 patients underwent a distalization to normalize the Caton index to 1.0-1.2. Results were evaluated using Cox' method. Patients with objective patellar instability were rated as 11% excellent, 52% good, 33% fair, and 4% poor. All patients became stable except one who had a 6 degrees valgus alignment. Although 96% had improved stability, 33% of the patients still had pain. The patients with lateral tracking patella (potential instability) were rated as 37.5% excellent, 44% good, and 19% fair. The lower proportion of pain relief in patients with unstable patella is likely the result of the cartilage damage experienced by these patients following multiple dislocations. Thus the patient with lateral tracking patella without patella dislocations must be differentiated from the one with unstable patella. Their prognosis in pain relief is better.

Teardrop-femoral head distance after shelf acetabuloplasty for Perthes' disease

Shelf acetabuloplasty is an accepted treatment for Perthes' disease. Favourable outcomes have been reported. This study aimed at determining whether changes in femoral head subluxation after shelf acetabuloplasty occur and whether they predict outcome. We assumed that reduction of subluxation after shelf acetabuloplasty would improve the long-term outcome. During follow-up, growth presented as a source of error when comparing the amount of absolute subluxation. Correction for growth was achieved by calculating a subluxation index. This index showed a significant reduction during follow-up. There was no correlation between clinical and radiological outcome, but the fact that the subluxation index showed a decreasing trend could be promising regarding outcome. This might be one of the reasons why shelf acetabuloplasty produces its effect. Following shelf acetabuloplasty the enlarged acetabulum could possibly direct the growth of the femoral head to a better-contained joint. This could result in better joint congruity and lesser tendency to degenerative arthritis.

Bioenergetics in cardiac hypertrophy: mitochondrial respiration as a pathological target of NO*

A rat aortic banding model of cardiac hypertrophy was used to test the hypothesis that reversible inhibition of mitochondrial respiration by nitric oxide (NO*) elicits a bioenergetic defect in the hypertrophied heart. In support of this hypothesis, the respiration of myocytes isolated from hypertrophied hearts was more sensitive to exogenous NO* (IC(50) 200 +/- 10 nM vs. 290 +/- 30 nM in controls, P = 0.0064). Hypertrophied myocytes also exhibited significantly elevated inducible NO* synthase (iNOS). Consistent with this endogenous source for NO*, the respiration of hypertrophied myocytes was significantly inhibited at physiological O(2) tensions versus controls. Both the nonspecific NOS inhibitor nitro-L-arginine and the iNOS-specific inhibitor N-[3-(aminomethyl)- benzyl]acetamidine. 2HCl reversed this inhibition, with no effect on respiration of control myocytes. Consistent with an NO*-mediated mitochondrial dysfunction, the ability of intact perfused hearts to respond to a pacing workload was impaired in hypertrophy, and this effect was reversed by NOS inhibition. We conclude that endogenously generated NO* can modulate mitochondrial function in the hypertrophied heart and suggest that this bioenergetic defect may underlie certain pathological features of hypertrophy.

Is there a relation between neuropsychologic variables and quality of life after stroke?

OBJECTIVES

To describe the quality of life (QOL) of stroke patients and to distill neuropsychologic predictors for poor QOL.

DESIGN

A cohort study in which patients were neuropsychologically assessed at a mean of 72.2 days after stroke, with follow-up at a mean of 9.8 months after stroke.

SETTING

Research department of a rehabilitation center.

PATIENTS

A consecutive sample of 164 stroke patients (mean age, 55.2yr) recruited from a university hospital, a regional hospital, and a rehabilitation center.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Orientation, memory, attention and concentration, visuospatial and visuoconstructive functions, language, and arithmetic skills were assessed with neuropsychologic tests. QOL was assessed with the Sickness Impact Profile (SIP).

RESULTS

An overall mean SIP score +/- standard deviation of 20 +/- 11 showed that stroke has a high impact on everyday functioning. Further analyses indicated that QOL is related in particular to tests measuring spatiotemporal and/or sequential aspects of behavior. Forward/backward stepwise regression analysis (n = 106) showed that poor QOL was more likely if patients had a poor result on the Trailmaking Test (TMT) B and/or were women.

CONCLUSION

The predictive value of the TMT is most effective and very useful because the TMT is a short and economical procedure. However, the gender-related aspects of recovery deserve more attention, as does the possible bias that can be caused by the composition of a measurement. Further research is needed to refine predictive models that are needed to facilitate the development of more adequate, individual rehabilitation programs.

Elevated potassium intake inhibits neointimal proliferation in the swine coronary artery

BACKGROUND

Previously, we reported that elevated extracellular potassium concentration in vitro inhibited proliferation and migration of vascular smooth muscle cells, formation of free radical compounds by macrophages, and reduced platelet sensitivity to agonists. More recently, we described a reduction in neointimal proliferation after balloon angioplasty injury in the carotid arteries of rats associated with an elevation of dietary potassium intake during a 4-week experiment. In the present study we conducted a similar investigation in the swine coronary artery balloon angioplasty model.

PROCEDURES

Two groups of seven castrated male swine were studied; for 28 days the normal potassium group consumed a diet containing 0.25% potassium and the high potassium group ate diet containing 2.0% potassium. After 14 days on the diet, balloon angioplasty was performed. After an additional 14 days on the same diets the hearts were removed, and normal and lesioned sections of the artery were analyzed histologically.

RESULTS

The neointimal area was markedly less in the high potassium group than in the normal potassium group, 0.33+/-0.04 mm2 v 0.74+/-0.10 mm2 (P < .004). Neointimal area-to-total wall area ratio in the normal potassium group averaged 0.199+/-0.018, significantly greater than the ratio computed for the elevated potassium group, 0.120+/-0.015 (P < .006).

CONCLUSION

These results support the hypothesis that a high level of dietary potassium intake inhibits neointimal proliferation after balloon angioplasty in the swine coronary artery.

Nitric oxide partitioning into mitochondrial membranes and the control of respiration at cytochrome c oxidase

An emerging and important site of action for nitric oxide (NO) within cells is the mitochondrial inner membrane, where NO binds to and inhibits members of the electron transport chain, complex III and cytochrome c oxidase. Although it is known that inhibition of cytochrome c oxidase by NO is competitive with O2, the mechanisms that underlie this phenomenon remain unclear, and the impact of both NO and O2 partitioning into biological membranes has not been considered. These properties are particularly interesting because physiological O2 tensions can vary widely, with NO having a greater inhibitory effect at low O2 tensions (<20 microM). In this study, we present evidence for a consumption of NO in mitochondrial membranes in the absence of substrate, in a nonsaturable process that is O2 dependent. This consumption modulates inhibition of cytochrome c oxidase by NO and is enhanced by the addition of exogenous membranes. From these data, it is evident that the partition of NO into mitochondrial membranes has a major impact on the ability of NO to control mitochondrial respiration. The implications of this conclusion are discussed in the context of mitochondrial lipid:protein ratios and the importance of NO as a regulator of respiration in pathophysiology.

Shelf acetabuloplasty for Perthes' disease: 12-year follow-up

The goal of all therapies for Perthes' disease is to achieve an optimal shape of the acetabulum and an optimal coverage of the femoral head. Thirty patients who were included in this follow-up study (mean follow-up 12 years) underwent a shelf acetabuloplasty for Catterall group III or IV. The mean IOWA hip score at follow-up was 96 (max. 100 points, range 74-100). The mean acetabular-head quotient increased from 82.9% pre-operatively to 107.9% postoperatively, and remained 102.4% at follow-up. There was a decrease in mean lateral subluxation ratio from 1.44 pre-operatively to 1.27 postoperatively, which remained 1.23 at follow-up. According to the Stulberg classification in the 18 adult hips, 6 hips had a good result (Stulberg 1 or 2), 10 hips had a fair result (Stulberg 3), and 2 hips had a poor result (Stulberg 4 or 5). These results appear to be better than the natural history as described by Stulberg. Shelf acetabuloplasty can be considered as an appropriate surgical treatment for severe cases of Perthes' disease.

Mechanisms of cell signaling by nitric oxide and peroxynitrite: from mitochondria to MAP kinases

Many of the biological and pathological effects of nitric oxide (NO) are mediated through cell signaling pathways that are initiated by NO reacting with metalloproteins. More recently, it has been recognized that the reaction of NO with free radicals such as superoxide and the lipid peroxyl radical also has the potential to modulate redox signaling. Although it is clear that NO can exert both cytotoxic and cytoprotective actions, the focus of this overview are those reactions that could lead to protection of the cell against oxidative stress in the vasculature. This will include the induction of antioxidant defenses such as glutathione, activation of mitogen-activated protein kinases in response to blood flow, and modulation of mitochondrial function and its impact on apoptosis. Models are presented that show the increased synthesis of glutathione in response to shear stress and inhibition of cytochrome c release from mitochondria. It appears that in the vasculature NO-dependent signaling pathways are of three types: (i) those involving NO itself, leading to modulation of mitochondrial respiration and soluble guanylate cyclase; (ii) those that involve S-nitrosation, including inhibition of caspases; and (iii) autocrine signaling that involves the intracellular formation of peroxynitrite and the activation of the mitogen-activated protein kinases. Taken together, NO plays a major role in the modulation of redox cell signaling through a number of distinct pathways in a cellular setting.

Increased sensitivity of mitochondrial respiration to inhibition by nitric oxide in cardiac hypertrophy

Cardiac hypertrophy is a significant risk factor for the development of congestive heart failure (CHF). Mitochondrial defects are reported in CHF, but no consistent mitochondrial alterations have yet been identified in hypertrophy. In this study selective metabolic inhibitors were used to determine thresholds for respiratory inhibition and to reveal novel mitochondrial defects in hypertrophy. Cardiac hypertrophy was produced in rats by aortic banding. Mitochondria were isolated from left ventricular tissue and the effects of inhibiting respiratory complexes I and IV on mitochondrial oxygen consumption were measured. At 8 weeks post-surgery, 65+/-2% complex IV inhibition was required to inhibit respiration half maximally in control mitochondria. In contrast, only 52+/-6% complex IV inhibition was required to inhibit respiration half maximally in mitochondria from hypertrophied hearts (P=0.046). This effect persisted at 22 weeks post-surgery and was accompanied by a significant upregulation of inducible nitric oxide synthase (iNOS, 3.0+/-0.7-fold, P=0.006). We conclude that respiration is more sensitive to complex IV inhibition in hypertrophy. Nitric oxide is a well documented inhibitor of complex IV, and thus the combination of increased NO(.)from iNOS and an increased sensitivity to inhibition of one of its targets could result in a bioenergetic defect in hypertrophy that may be a harbinger of CHF.

Results with the M. E. Müller cemented, straight-stem total hip prosthesis: a 10-year historical cohort study in 180 women

In 1986, 242 M. E. Muller (MEM) cemented, straight-stem total hip arthroplasty prostheses were implanted in 229 patients; 15 hips (13 patients) were lost to follow-up. Of the remaining 227 implants, 180 were placed in women, and 47 were placed in men (each with mean age, 71 +/- 7.7 years). After 10 years, 66 patients had died, and 152 implants were still in situ. As a result of aseptic loosening, 9 hips were revised (5 femoral and 4 acetabular components); two of these patients had a Girdlestone as a result of postoperative infection. Because 50% of the men died during follow-up, further analysis was performed with the 180 implants in women. The incidence of revision for aseptic loosening was 5.9 per 1,000 implants. The cumulative survival rate after 10 years was 94%. Survival was not influenced significantly by age, indication for operation, or having a contralateral hip prosthesis. The 10-year follow-up results for the MEM straight-stem total hip prosthesis in our hospital are satisfactory despite the probability that the cement mantle produced with this stem is not uniform in thickness.

Cyclic GMP-dependent protein kinase expression in coronary arterial smooth muscle in response to balloon catheter injury

Arterial smooth muscle cells undergo phenotypic and proliferative changes in response to balloon catheter injury. Nitric oxide (NO) and cGMP have been implicated in the inhibition of vascular smooth muscle cell proliferation and phenotypic modulation in cultured-cell studies. We have examined the expression of the major cGMP receptor protein in smooth muscle, cGMP-dependent protein kinase I (PKG), in response to balloon catheter injury in the swine coronary artery. On injury, there was a transient decrease in the expression of PKG in neointimal smooth muscle cells when compared with medial smooth muscle cells. The decrease in PKG expression was observed in the population of proliferating cells expressing the extracellular matrix protein osteopontin but not in cells present in the uninjured portion of the media. Coincident with the suppression of PKG expression in neointimal cells after injury, there was a marked increase in the expression of type II NO synthase (inducible NOS [iNOS], NOS-II) in the neointimal cells. These results suggest that PKG expression is transiently reduced in response to injury in the population of coronary arterial smooth muscle cells that are actively proliferating and producing extracellular matrix proteins. The reduction in PKG expression is also correlated temporally with increases in inflammatory activity in the injured vessels as assessed by iNOS expression. Coupled with our current knowledge regarding the role of PKG in the regulation of cultured cell phenotypes, these results imply that PKG may also regulate phenotypic modulation of vascular smooth muscle cells in vivo as well.

High potassium intake inhibits neointima formation in the rat carotid artery balloon injury model

Recently, we reported that elevated extracellular potassium concentration in vitro inhibited proliferation and migration of vascular smooth muscle cells, formation of free radical compounds by macrophages, and reduced platelet sensitivity to agonists. In the present study we analyzed the effects of long-term, in vivo elevation of extracellular potassium concentration resulting from changes in dietary potassium intake on the vascular response to injury. The rat carotid artery balloon injury model was employed in 70 adult Sprague Dawley rats assigned to three groups. Beginning 14 days before surgical placement of the carotid lesion and continuing until death, the animals were fed diets containing either low (0.1% potassium, n = 25), normal (1.5% potassium, n = 19), or high potassium (4.0% potassium, n = 26). Fourteen days postsurgery the animals were killed and the arteries were analyzed to determine quantitatively the ratio of neointimal to medial area. Dietary potassium had a significant effect on arterial plasma potassium concentration (one-way analysis of variance, P < .01). Group mean and standard errors were 4.26+/-0.12 mmol/L for the low-potassium group, 5.22+/-0.19 mmol/L for normal, and 5.80+/-0.23 mmol/L for the high-intake group. Increases in dietary potassium attenuated neointima formation significantly (P < .05, one-way analysis of variance), with the mean ratio of neointimal area to medial area being 0.447+/-0.106 for the low-intake animals, 0.384+/-.116 for normal, and 0.240+/-.046 for the high-intake group. These results are consistent with a hypothesis that a high level of potassium intake is effective in inhibiting neointima formation in vivo.

Concentration-dependent effects of nitric oxide on mitochondrial permeability transition and cytochrome c release

The mitochondrial permeability transition pore (PTP) and associated release of cytochrome c are thought to be important in the apoptotic process. Nitric oxide (NO( small middle dot)) has been reported to inhibit apoptosis by acting on a variety of extra-mitochondrial targets. The relationship between cytochrome c release and PTP opening, and the effects of NO( small middle dot) are not clearly established. Nitric oxide, S-nitrosothiols and peroxynitrite are reported to variously inhibit or promote PTP opening. In this study the effects of NO( small middle dot) on the PTP were characterized by exposing isolated rat liver mitochondria to physiological and pathological rates of NO( small middle dot) released from NONOate NO( small middle dot) donors. Nitric oxide reversibly inhibited PTP opening with an IC(50) of 11 nm NO( small middle dot)/s, which can be readily achieved in vivo by NO( small middle dot) synthases. The mechanism involved mitochondrial membrane depolarization and inhibition of Ca(2+) accumulation. At supraphysiological release rates (>2 micrometer/s) NO( small middle dot) accelerated PTP opening. Substantial cytochrome c release occurred with only a 20% change in mitochondrial swelling, was an early event in the PTP, and was also inhibited by NO( small middle dot). Furthermore, NO( small middle dot) exposure resulted in significantly lower cytochrome c release for the same degree of PTP opening. It is proposed that this pathway represents an additional mechanism underlying the antiapoptotic effects of NO( small middle dot).

A systematic literature review to identify the best method for a single level anterior cervical interbody fusion

The goal of this systematic literature review was to determine, for patients with degenerative disc disease, which method of single-level anterior cervical interbody fusion using the anterior approach gives the best clinical and radiological outcome. The number of new techniques for obtaining a solid fusion has increased rapidly, but the rationale for choosing between different techniques is unclear. Randomised comparative studies on anterior cervical interbody fusions were identified in a sensitive Medline, Cochrane and Current Contents database search. Two independent reviewers evaluated the articles that met the selection criteria, using a checklist. The search yielded eight randomised, controlled trials for the systematic literature review. Three of these studies were judged to be of sufficient quality with regard to methodology and the information provided. In the three articles, five different treatment methods were investigated, four of which were interbody fusions. Fusion rates varied between 28% for an allograft method and 63% for a discectomy-alone method. In one study, kyphosis varied from 40% to 62% between treatments. Good clinical outcome (disability, pain and symptoms) ratings varied from 66% to 82%. A meta-analysis to determine the best method for an anterior interbody fusion could not be performed due to the heterogeneity of the methods reported and because no standard outcome parameter was used. From this systematic literature review, a gold standard for the treatment of degenerative disc disease could not be identified.

A new surgical technique for the silicone gastric band in the presence of a large hiatus hernia

BACKGROUND

The purpose of this study was to establish the efficacy of a new surgical technique for the placement of the silicone gastric band (LAP-Band) in the presence of a large (>5 cm) hiatus hernia.

METHOD

Hiatus hernias >5 cm were identified by endoscopy and barium meal in 6 patients. Each patient underwent hiatal hernia repair and attempted gastrodesis with laparoscopic placement of a gastric band.

RESULTS

At 6 months, there were no complications. Mean weight loss was 16 kg.

CONCLUSION

Repair of hiatus hernia with hiatal repair and gastrodesis of the posterior aspect of the stomach may allow some patients to undergo a procedure previously considered contraindicated.

A preliminary comparison of the psychological impact of laparoscopic gastric banding and gastric bypass surgery for morbid obesity

BACKGROUND

Laparoscopic gastric banding has introduced a new element into weight reduction surgery. The authors compared subjects who had undergone a laparoscopic gastric banding (lap-band) procedure with those who had undergone a gastric bypass operation on relevant psychological and behavioral parameters.

METHODS

A self-report questionnaire developed by the researchers was used. It included questions about aspects of food and eating as well as attitudinal items relating to the outcome of the surgery.

RESULTS

There were significant differences between the lap-band group and the gastric bypass group in their distance from their desired weight, their eating, and their attitudes.

CONCLUSION

9 months after surgery, gastric bypass surgery appears to be the superior procedure on several parameters. The surgery induction process may be critical. Evaluation at later stages is vital.

Abdominal aortic aneurysm repair via percutaneous endovascular stenting in the swine model

Abdominal aortic aneurysms (AAAs) are the 13th leading cause of death in the United States. Endovascular stent grafts are currently being investigated in clinical trials as an alternative method for treatment of AAA. Twelve pigs underwent creation of AAA using the abdominus rectus fascia. Postoperatively, all 12 animals underwent angiography, which demonstrated turbulent flow within the created aneurysms. Four of the animals were not stented and served as controls. Eight animals underwent subsequent percutaneous placement of a covered endovascular stent via a right femoral sheath, and the stents were deployed between the renal arteries and the aortic bifurcation. The animals were maintained for 120 days before sacrifice and necropsy. Unstented animals (4) died within 6 days, 3 from rupture. Eight animals underwent endovascular stenting: 5 survived without complications, 3 deaths within 2 days were related to technical complications. The 5 surviving animals were sacrificed at 120 days, and necropsy was conducted with in situ dissections of the aorta and intact stent: 3 experimental animals had correct anatomic positioning of the stent, and 2 had inexact stent placement but survived 120 days with AAA thrombosis. Treatment of AAA in this swine model has been demonstrated via placement of a percutaneous covered stent.

Gross and microscopic pathological changes associated with nonthoracotomy implantable defibrillator leads

BACKGROUND

Although the effects of epicardial implantable cardioverter-defibrillator (ICD) leads on underlying cardiac tissue have been reported, the gross and microscopic changes associated with endocardial ICD leads are less well described. This study describes the gross and microscopic changes associated with endocardial ICD leads in humans.

METHODS AND RESULTS

The hearts from 8 patients were examined. At the time of ICD implantation, the patients' mean age was 47+/-11 years, and the left ventricular ejection fraction was 0.24+/-0.10. Four patients had ischemic heart disease, and 4 had dilated cardiomyopathy. Five hearts were examined after transplantation; 3, after death. The electrode-myocardial interfaces were characterized by intense endocardial fibrosis and were remarkably consistent. Each lead was encased by a ring of fibroelastic tissue, and there was fibrosis of the right ventricular myocardium adjacent to the leads. Fibrosis involved the tricuspid valve in 5 patients, and 1 had perforation of the valve by the lead. Microscopically, interstitial fibrosis was adjacent to each lead in the current path of ICD shocks. Acute cell injury was present only in the hearts that had received recent shocks.

CONCLUSIONS

The ICD electrode-myocardial interface is characterized by intense fibrosis. The fibrosis associated with endocardial ICD leads and the cumulative acute damage produced by defibrillation discharges may explain changes in the defibrillation and pacing thresholds and the difficulty of lead extraction that can be encountered with transvenous ICD systems.

Local delivery of ethanol inhibits intimal hyperplasia in pig coronary arteries after balloon injury

BACKGROUND

Smooth muscle cell (SMC) hyperplasia is an important mechanism of restenosis after coronary angioplasty and the primary mechanism of restenosis within coronary stents. Ethanol has been shown to reduce the response of SMCs to local growth stimulants in vitro. This study was carried out to determine whether local delivery of ethanol solution could reduce intimal hyperplasia induced by balloon injury.

METHODS AND RESULTS

Three groups of juvenile domestic pigs underwent oversized balloon dilation injury of the left anterior descending and left circumflex coronary arteries. Immediately after the balloon injury, one of the arteries was randomized to local delivery of 15% ethanol with a local delivery balloon catheter, and the other received no further treatment. Histological and morphometric studies were carried out at 2 weeks in group 1 (n=16) and at 4 weeks in group 2 (n=10). In the third group (n=15), animals were killed at days 4, 8, and 14 after balloon injury, and coronary artery segments were studied by immunohistochemical staining against proliferating cell nuclear antigen (PCNA) and bromodeoxyuridine (BrdU). Histological injury scores were not different between the ethanol-treated and untreated arterial segments in either group 1 or 2. The neointimal areas were significantly smaller in the ethanol-treated arterial segments than in the untreated segments (0.25+/-0.08 versus 0.57+/-0.08 mm2, P=.004, at 2 weeks; 0.33+/-0.05 versus 0.54+/-0.07 mm2, P=.03, at 4 weeks). SMC proliferative activity was significantly lower in ethanol-treated arteries than in untreated arteries at 4 and 8 days after injury by BrdU and PCNA staining.

CONCLUSIONS

Local delivery of 15% ethanol solution to pig coronary arteries significantly decreased the SMC proliferative activity and neointimal formation induced by balloon dilation injury.

Eating behavior and the experience of hunger following gastric bypass surgery for morbid obesity

BACKGROUND

Numerous different factors may contribute to the varying degrees of success observed following gastric bypass surgery. It is likely that alterations in the subjective experiences of hunger and satiety, as well as behavioral factors, are important. Our aim was to investigate the association of several factors, including qualitative aspects of hunger and satiety, eating patterns, and the emotional valence of different foods, to the weight loss that occurred following obesity surgery.

METHODS

A questionnaire covering aspects of hunger, eating and satiety was administered to three groups: (1) a group of people who had undergone gastric bypass surgery with an acceptable weight loss; (2) a morbidly obese group of patients prior to their surgical intervention; (3) a group of people of normal weight.

RESULTS

There were significant differences amongst the three groups in scoring on standardized eating disorder scales, in the amount they could eat, and in the experience of hunger. The presurgery, waiting-list group was more receptive to food-related than interoceptive cues when deciding to stop eating. 'Eating styles' also differed across the groups.

CONCLUSIONS

It is concluded that changes in specific food-related behaviors and other psychological variables interact with the physical restriction to eating. The relative weighting of other variables needs further exploration.

Pressure-independent effects of AT1-receptor antagonism on cardiovascular remodeling in aortic-banded rats

To determine the role of angiotensin II-receptor blockade on cardiovascular remodeling in a pressure-overload model of cardiac hypertrophy, a subdiaphragmatic aortic band was placed in adult male Sprague-Dawley rats. Aortic-banded (AB) rats were left untreated or were losartan (Los; 250 mg/l) treated (AB-Los). Sham-operated (S) controls were either left untreated or treated with Los (S-Los). After 4 wk, rats were catheterized for measurement of mean arterial pressures [carotid (CMAP) and femoral (FMAP), in mmHg]. Hearts were perfused on a modified Langendorff system, and minimal coronary resistance (MCR) was determined. Hearts were then perfusion fixed, total and regional heart weights were recorded, and sections were processed for morphology. Changes in coronary artery medial thickness and perivascular fibrosis were assessed by quantitative image analysis. CMAP was significantly higher in AB and AB-Los than in S or S-Los (P < 0.05). There was no difference in FMAP in AB vs. S, but AB-Los and S-Los had lower FMAPs than S. Total heart weight and left ventricular weight-to-body weight ratios were increased in AB and AB-Los compared with S and S-Los (P < 0.05). MCR of AB was greater than S and S-Los. MCR of AB-Los was significantly lower than AB and was not significantly different from S and S-Los. In coronary vessels, medial thickness was greatest in AB, whereas there was no difference among AB-Los, S, and S-Los. Similarly, the increase in perivascular fibrosis was greatest in AB, and there was no difference among AB-Los, S, and S-Los. These data suggest that angiotensin II, independent of increased arterial pressure, is critical for the development of the vascular and fibrotic changes that occur in this model of pressure-overload hypertrophy.

Abdominal wall sinus: a late complication of gallstone spillage during laparoscopic cholecystectomy

Long term complications of laparoscopic cholecystectomy are uncommon. However, as experience with this procedure accumulates, sporadic reports of non-biliary complication have been published. We report a case of abdominal wall sinus formation secondary to gallbladder perforation and stone spillage occurring during laparoscopic cholecystectomy.

Reduction of thrombus formation without inhibiting coagulation factors does not inhibit intimal hyperplasia after balloon injury in pig coronary arteries

BACKGROUND

The proposed mechanisms of restenosis after coronary angioplasty include neointima formation, vessel wall remodeling and mural thrombus. Poloxamer 188 does not inhibit coagulation factors, but was shown to reduce mural thrombus formation in pig coronary arteries after intracoronary stenting in an acute study. This study was performed to examine whether this agent may reduce neointima formation.

METHODS

Thirty domestic juvenile pigs of weight 20-30 kg were anesthetized. A left angiogram was performed via a femoral artery. Proximal left anterior descending and circumflex arteries were dilated three times with a 20-30% oversized coronary angioplasty balloon catheter. Fifteen animals were allocated randomly to receive intravenous infusions of poloxamer 188, starting 30 min before angioplasty and continuing for 24 h. The remaining 15 received intravenous 0.45% saline and served as controls. The animals were killed 2 weeks after the angioplasty. Histologic studies of the arteries were performed. The severity of the injury and the amount of thrombus material incorporated in the neointima were assessed by semiquantitative methods.

RESULTS

There was no significant difference between injury scores in the two groups. Thrombus material in the neointima in the treatment group was significantly less than that in those of the control group (thrombus areas 0.013 +/- 0.004 compared with 0.029 +/- 0.006 mm2, P < 0.02), but there were no significant differences between the neointimal (0.60 +/- 0.08 and 0.60 +/- 0.13 mm2) and luminal (2.51 +/- 0.21 and 2.44 +/- 0.26 mm2) areas in treatment and control groups.

CONCLUSION

Continuous 24 h intravenous infusion of poloxamer 188 after balloon injury in pig coronary arteries may reduce mural thrombus formation significantly, but did not reduce neointima formation.

Captopril prevents vascular and fibrotic changes but not cardiac hypertrophy in aortic-banded rats

To determine the role of the renin-angiotensin system (RAS) on cardiovascular remodeling in a pressure overload model of cardiac hypertrophy, a subdiaphragmatic aortic band was placed in adult male, Sprague-Dawley rats. Rats were left untreated (AB) or given captopril (Cap, 400 mg/l) (AB-Cap). Sham-operated controls were either left untreated (S) or given Cap (S-Cap). After 4 wk, rats were catheterized, and carotid and femoral mean arterial pressures (CMAP and FMAP in mmHg, respectively) were recorded. Hearts were isolated, and minimal coronary resistance (MCR) was determined. Hearts were then perfusion fixed, total and regional heart weights were recorded, and sections were processed for vessel morphology. Changes in coronary artery medical thickness and perivascular fibrosis were assessed by quantitative image analysis. CMAP was significantly higher in AB and AB-Cap than S or S-Cap rats (P < 0.05). There was no difference in FMAP in AB vs. S rats, but AB-Cap and S-Cap had lower FMAP values than S rats. Total heart weight and left ventricular weight-to-body weight ratios were increased in AB and AB-Cap rats compared with S and S-Cap rats (P < 0.05). MCR of AB was greater than S and S-Cap rats. MCR of AB-Cap rats was significantly greater than S and S-Cap rats but was significantly less than AB rats. In coronary vessels, medial thickness was greatest in AB, whereas there was no difference among AB-Cap, S, and S-Cap rats. Similarly, the increase in perivascular fibrosis was greatest in AB rats, and there was no difference among AB-Cap, S, and S-Cap rats. These data suggest that the RAS, independent of increased arterial pressure, is critical for the development of the vascular and fibrotic changes that occur in this model of pressure overload hypertrophy.

23Na and 31P nuclear magnetic resonance studies of ischemia-induced ventricular fibrillation. Alterations of intracellular Na+ and cellular energy

To clarify the role of Na+i, pHi, and high-energy phosphate (HEP) levels in the initiation and maintenance of ischemia-induced ventricular fibrillation (VF), interleaved 23Na and 31P nuclear magnetic resonance spectra were collected on perfused rat hearts during low-flow ischemia (51 minutes, 1.2 mL/g wet wt). When untreated, 50% of the hearts from normal (sham) rats and 89% of the hypertrophied hearts from aorticbanded (band) rats (P < .01 versus sham) exhibited VF. Phosphocreatine content was significantly higher in sham than band hearts during control perfusion (53.3 +/- 1.6 versus 39.8 +/- 2.0 mumol/g dry wt). Before VF at 20 minutes of ischemia, Na+i accumulation was greater in hearts that eventually developed VF than in hearts that did not develop VF for both band and sham groups (144% versus 128% of control in sham; P < .005) and was the strongest metabolic predictor of VF; ATP depletion was also greater for VF hearts in the sham group. Infusion of the Na(+)-H+ exchange inhibitor 5-(N,N-hexamethylene)-amiloride prevented VF in sham and band hearts; reduced Na+i accumulation but similar HEP depletion were observed compared with VF hearts before the onset of VF. Rapid changes in Na+i, pHi, and HEP began with VF, resulting in intracellular Na+i overload (approximately 300% of control) and increased HEP depletion. A delayed postischemic functional recovery occurred in VF hearts, which correlated temporally with the recovery of Na+i. In conclusion, alterations in Na+i were associated with spontaneous VF transitions, consistent with involvement of excess Na+i accumulation in VF initiation and maintenance and with previously reported alterations in Ca2+i with VF.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term histologic patency after percutaneous transluminal coronary angioplasty is predicted by the creation of a greater lumen area

OBJECTIVES

This study assessed the relation between histologic acute and long-term lumen size after coronary angioplasty.

BACKGROUND

Angiographic studies suggest that the creation of a larger acute lumen is associated with a reduced incidence of restenosis. Histologic evaluation of the influence of the acute lumen on late outcome has not been previously reported.

METHODS

Detailed histologic examination and planimetry were performed in 28 postmortem coronary arteries subjected to angioplasty at an average of 71 weeks antemortem. The lumen area on each histologic segment was defined as the final lumen area. The lumen area immediately after angioplasty, the acute lumen area, was defined by the sum of the neointimal area plus final lumen. A final lumen area > or = 25% of the arterial area was considered a long-term success; a final lumen area < 25% was considered a long-term failure.

RESULTS

Arterial size and neointimal area were similar in long-term successes and failures. In successes, the mean (+/- SD) acute lumen area was greater than in failures (4.1 +/- 1.9 vs. 2.7 +/- 1.4 mm2, respectively, p < 0.001). The acute lumen area as a percent of arterial area was 46 +/- 10% in successes versus 27 +/- 11% in failures (p < 0.0001). The corresponding estimated mean acute lumen diameter stenosis was 24 +/- 8% in successes versus 42 +/- 12% in failures (p < 0.0001). Plaque area was greater in failures (7.1 +/- 3.2 mm2) than in successes (4.8 +/- 2.4 mm2, p < 0.002).

CONCLUSIONS

Neointimal proliferation after angioplasty occurs in all dilated coronary arteries, and the amount of neointimal growth is independent of vessel size. The creation of a larger lumen and a larger lumen as a percent of vessel size were associated with an improved long-term histologic patency.

Preischemic glycogen reduction or glycolytic inhibition improves postischemic recovery of hypertrophied rat hearts

The purpose of this study was to determine whether metabolites produced by glycolysis during ischemia significantly contribute to myocardial injury of hypertrophied hearts. The accumulation of glycolytic metabolites during ischemia was reduced by means of glycogen reduction or by treatment with the glycolytic inhibitor, 2-deoxy-D-glucose (2-DG) before ischemia. Hearts from aortic-banded (Band) and sham-operated (Sham) rats (8 wk postop) were isolated, perfused with Krebs buffer, and had a left ventricular (LV) balloon to measure developed pressure. A 15-min perfusion with hypoxic buffer (glycogen reduction, GR) or a 10-min perfusion with 10 mM 2-DG (glycolytic inhibition) was followed by 25 min global, normothermic, no-flow ischemia and 30 min normoxic reperfusion. Heart weights were greater in Band than Sham [2.76 +/- 0.06 vs. 1.5 +/- 0.04 (mean +/- SE) g; P < 0.001]. GR and 2-DG each resulted in reduced ATP levels measured at the beginning of ischemia in both Band and Sham groups compared with untreated groups, but there were no differences among groups after 25 min of ischemia. Myocardial lactate levels at the end of ischemia were significantly reduced in both Band and Sham hearts with GR or 2-DG compared with untreated controls. Recovery of LV function after ischemia and reperfusion was significantly improved in Band after GR (206% increase) and after 2-DG treatment (126% increase) compared with their respective untreated controls. Diastolic dysfunction during reperfusion was ameliorated in Band by preischemic GR but not by 2-DG treatment.(ABSTRACT TRUNCATED AT 250 WORDS)