Electron tunneling in azurin: the coupling across a beta-sheet.

BACKGROUND: We would like to understand how electron flow is controlled in biological molecules. Standard theories calculate the rate for long distance electron transfer (ET) as the product of electronic coupling (the square of the electron tunneling matrix element) and nuclear (Franck-Condon) factors. Much attention has been directed to the role of protein secondary and tertiary structure in the tunneling coupling, focusing on the interplay between different types of chemical bonds. Here we have evaluated the relative contributions of covalent bonds, hydrogen bonds and through-space jumps in coupling through a beta-strand or across a beta-sheet section of a blue copper protein, azurin. RESULTS: We have analyzed four distant electronic couplings in azurin. Each coupling is between the copper atom and a Ru(bpy)2(im) complex attached to a histidine on the protein surface. In three experiments the intervening medium was a simple beta-strand, while in the fourth experiment it was a section of beta-sheet. CONCLUSIONS: We have shown that electron tunneling in a protein can be broken down into ET 'tubes' of pathways through specific covalent and hydrogen bonds. These ET tubes encapsulate trivial interference effects and can expose crucial inter-tube interference effects. In coupling through a beta-sheet, hydrogen bonds are as important as covalent links, and are the primary source for tube interference.

Personality features of obsessive-compulsive disorder.

The authors evaluated personality dysfunction in 23 patients with primary obsessive-compulsive disorder and an age- and sex-matched group of patients with major depressive disorder. There were no significant differences between the two patient groups with respect to mean personality trait scores or the frequency or type of personality disorder diagnosis. A mixed personality disorder with avoidant, dependent, and passive-aggressive features was most commonly observed in the obsessive-compulsive group. There was a very low frequency of schizoid or compulsive personality disorder.

The Tridimensional Personality Questionnaire in major depression.

The authors examined Tridimensional Personality Questionnaire scores in 40 patients with unipolar nonpsychotic major depression before and after antidepressant treatment. They found that scores on the novelty seeking and reward dependence dimensions were not affected by depressed state or by treatment response status. However, scores on the harm avoidance dimension were significantly lower in antidepressant responders and were altered by depressed state.

Influence of fructose on the glycogen synthase and phosphorylase systems in rat liver.

Fructose and glucose, when administered as a single, large intravenous dose (500 mg/kg) produced opposite effects on key regulatory enzymes of glycogen metabolism in intact normal fed animals. Glucose rapidly stimulated glycogen synthase phosphatase activity and increased the proportion of glycogen synthase in the active (I) form as expected; fructose reduced synthase phosphatase activity and the proportion of synthase in the I form. Glucose also stimulated a reduction in the proportion of phosphorylase in the active (a) form, whereas fructose stimulated an increase in the proportion of phosphorylase in thea form. The effect of fructose was not mediated by an increase in cyclic adenylate (cAMP) concentration nor by a conversion of phosphorylase kinase b to phosphorylase kinase a. As expected, the concentration of ATP decreased significantly. The increase in proportion of phosphorylase in the a form may be due to stimulation of phosphorylase kinase b activity by a decrease in the intracellular ATP:Mg++ ratio or by increase in intracellular Ca++ concentration. The mechanism of the fructose-induced change in synthase phosphatase activity and in synthase I activity is unknown.

Personality and depression.

Several studies suggest that measures of personality traits and disorders are affected by depressed state. However, none of the studies to date have evaluated the effect of depressed mood on personality using current diagnostic criteria. The effect of depressed mood on personality scale scores and personality disorder diagnoses using the Millon Clinical Multiaxial Inventory was assessed in 42 depressed patients. There was a significant alteration in mean personality trait scores and reduction in personality disorder diagnosis between the depressed and remitted states. The clinical and theoretical implications of these findings are discussed.

Personality and family history of depression in patients with affective illness.

The presence of a family history of depression may distinguish clinically important subgroups of depressed patients. Depressed patients with and without a family history of depression may differ on several clinical features. There are limited data, however, on potential differences in personality variables between patients with and without familial depression. We examined personality measures in 41 depressed subjects with and without a familial history of depression in both the depressed and remitted state. Patients with no family history of depression had significantly higher mean personality trait scores on the dependent and compulsive personality scales. The clinical and theoretical implications of these findings are discussed.

Application of thoracoscopy for diseases of the spine.

For anterior approaches to the thoracic spine, a posterolateral thoracotomy has been the standard approach. Recent expanded experience with video-assisted thoracic surgical techniques has allowed us to perform many thoracic spine procedures that previously required open approaches. These procedures include drainage of spinal abscesses, biopsy of vertebral bodies, discectomy for a herniated nucleus pulposus, and anterior releases for kyphoscoliosis. All procedures were successful, but experience is limited and follow-up still short. It is hoped that further experience will prove that this less invasive approach can be widely applied in the practice of thoracic spinal surgery.

Video-assisted thoracic surgery for the anterior approach to the thoracic spine.

Standard anterior approach to the thoracic spine is by a posterolateral thoracotomy. Because of the morbidity associated with this incision, video-assisted thoracic surgery (VATS) has been used as a less invasive approach for many intrathoracic disease processes. We have applied VATS for anterior access to the thoracic spine. From April 1991 to September 1994, 95 patients underwent thoracic spine procedures using thoracoscopy as the sole method of anterior approach. Procedures performed include discectomy for herniation (n = 57), multilevel discectomy for correction of spinal deformity (27), corpectomy (9), and drainage of intervertebral disc space abscess (2). All levels of the thoracic spine from the T2-T3 level to the T12-L1 interspace were approached. Forty-four procedures were performed through the left side of the chest and 41 through the right. The planned procedure was accomplished by VATS in all but 1 patient who required conversion to an open procedure because of scarring from a previous spine procedure. Mean operative time was 2 hours 24 minutes (range, 45 minutes to 5 hours 10 minutes). Average chest tube duration was 1.4 days, and mean length of stay was 4.82 days (range, 2 to 21 days). Complications included intercostal neuralgia (6), atelectasis (5), excessive epidural blood loss (2,500 mL; 2) and temporary paraparesis in a scoliosis patient related to operative positioning. We conclude that VATS offers a new, less morbid anterior approach to the thoracic spine. Although there is a significant learning period, most procedures requiring an anterior access can be performed safely by this technique. The VATS approach mandates an expanded role for the thoracic surgeon in operative spine disease.

Reoperation for herniated thoracic discs.

OBJECT: In this review the authors address the surgical strategies required to resect residual herniated thoracic discs. METHODS: Data obtained in 15 patients who had undergone prior thoracic discectomy and who harbored residual or incompletely excised symptomatic thoracic discs were reviewed retrospectively. The surgical procedures that had failed to excise the herniated discs completely included 11 posterolateral approaches, one thoracotomy, and three thoracoscopy-guided surgical procedures. Of the lesions that were incompletely resected or residual, there were 13 central calcified, two soft. 12 extradural, and three intradural discs. Indications for reoperation were often multiple in each patient and included misidentification of the level of disc disease at the initial operation (five cases), abandoning the procedure because of intraoperative spinal cord injury (three cases), inadequate visualization of the pathological entity (eight cases), migration of a soft disc fragment within the spinal canal (one case), and intradural disc extension (three cases). The symptoms at the time of reoperation included myelopathy in 13 patients and radicular pain in two patients. The mean interval before reoperation was 150 days (range 1 day-4 years). The reoperation procedures included one thoracotomy and 14 video-assisted thoracoscopic procedures performed ipsilateral (11 cases) or contralateral (four cases) to the site of the initial surgery. The herniated disc material was excised completely in all 15 cases without causing new neurological deficits. Reoperation complications included atelectasis in three patients, intercostal neuralgia in two, a loosened screw that required removal in one, residual intradural disc herniation that required a second reoperation in one patient, and a cerebrospinal fluid leak in one patient. Of the 13 patients who experienced myelopathy prior to operation, 10 recovered neurological function and three stabilized. All patients with radicular pain improved. CONCLUSIONS: Calcified, large, broad-based, centrally located, or transdural thoracic disc herniations can be difficult to resect. These lesions require a ventral operative approach to visualize the dura adequately for a safe and complete resection.

Laparoscopic fusion of the lumbar spine: minimally invasive spine surgery. A prospective multicenter study evaluating open and laparoscopic lumbar fusion.

STUDY DESIGN: Two hundred-forty consecutive patients underwent laparoscopic instrumented interbody fusion using custom-designed instrumentation and BAK (Sulzer Spine Tech, Minneapolis, MN) fusion cages. The surgeries were performed at eight spine centers during U.S. Food and Drug Administration investigational device evaluation clinical trials. This cohort was compared with 591 consecutive patients undergoing open anterior fusion with the same device. OBJECTIVES: To investigate the feasibility and safety of the laparoscopic approach compared with that of open procedures. SUMMARY OF BACKGROUND DATA: In other areas of medicine, advances in laparoscopic surgical procedures have resulted in reduced morbidity, expense, and pain when compared with results of the open counterpart. METHODS: The open anterior procedure was performed using a retroperitoneal approach. The laparoscopic procedure was performed transperitoneally with carbon dioxide insufflation to provide visualization using a 10-mm endoscope. Two hollow, titanium, threaded interbody implants packed with autologous bone were inserted into the diseased interspace. RESULTS: The laparoscopy group had a shorter hospital stay and reduced blood loss but had increased operative time. Operative time improved in the laparoscopy group as surgeons' experience increased. Operative complications were comparable in both groups, with an occurrence of 4.2% in the open approach and 4.9% in the laparoscopic approach. Overall, the device-related reoperation rate was higher in the laparoscopy group (4.7% vs. 2.3%), primarily as a result of intraoperative disc herniation. Conversion to open procedure in the laparoscopy group was 10%, with most cases predictable and preventable. CONCLUSIONS: The laparoscopic procedure is associated with a learning curve, but once mastered, it is effective and safe when compared with open techniques of fusion.

A technical report on video-assisted thoracoscopy in thoracic spinal surgery. Preliminary description.

STUDY DESIGN: This report is a preliminary description of the efficacy of video-assisted thoracoscopic surgery in thoracic spinal procedures that otherwise require open thoracotomy. OBJECTIVE: This report sought to describe the efficacy of video-assisted thoracoscopic surgery in thoracic spinal procedures that otherwise require open thoracotomy. SUMMARY OF BACKGROUND DATA: In a landmark study that compared video-assisted thoracoscopic surgery for peripheral lung lesions with thoracotomy, video-assisted thoracoscopic surgery reduced postoperative pain, improved early shoulder girdle function, and shortened hospital stay. METHODS: Video-assisted thoracoscopic surgery was performed in 12 thoracic spinal patients (herniated nucleus pulposus, infection, tumor, or spinal deformity) and is described in detail in this report. RESULTS: Video-assisted thoracoscopic surgery in thoracic spinal surgery resulted in little postoperative pain, short intensive care unit and hospital stays, and little or no morbidity. In the short follow-up period, there was no post-thoracotomy pain syndrome nor neurologic sequelae in these patients. Operative time decreased dramatically as experience was gained with the procedure. CONCLUSION: Given consistently improving surgical skills, a number of thoracic spinal procedures using video-assisted thoracoscopic surgery, including thoracic discectomy, internal rib thoracoplasty, anterior osteotomy, corpectomy, and fusion, can be performed safely with no additional surgical time or risk to the patient.

Laparoscopic approach to L4-L5 for interbody fusion using BAK cages: experience in the first 58 cases.

STUDY DESIGN: Operative reports were reviewed for patients who underwent laparoscopic fusion at the L4-L5 level and information regarding the mobilization of the vessels was recorded. OBJECTIVE: The purpose of this study was to describe variations in the approach used to address anatomical variations in the location of the great vessel bifurcation in the region of the L4-L5 intervertebral disc space when performing laparoscopic interbody fusion procedures. SUMMARY OF BACKGROUND DATA: Recent interest in laparoscopic spine surgery using threaded cages has resulted in questions regarding the ability to safely access the L4-L5 disc using this approach. The laparoscopic transperitoneal approach to L5-S1 is below the bifurcation of the great vessels, thus requiring minimal mobilization of the iliac vessels. However, the transperitoneal approach to L4-L5 may be complicated by the bifurcation of the great vessels anterior to this disc space. Difficulty in placing two cages may occur if the vessels cannot be adequately mobilized. METHODS: Data were collected for the consecutive series of the first 58 patients (40 males, 18 females; mean age 42.5 years) undergoing laparoscopic anterior lumbar interbody fusion (ALIF) at the L4-L5 level using BAK cages. Operative notes were reviewed to determine variations in the operative approach. In particular, it was recorded if the L4-L5 disc was accessed above, or below the bifurcation of the aorta and the vena cava, or between these structures. The blood loss, operative time, and length of hospitalization were compared with respect to approach variation. RESULTS: In 30 patients, the L4-L5 disc was accessed above the great vessel bifurcation, in 18 patients below the bifurcation, and in the remaining 10 patients, by passing between the vessels. There were no statistically significant differences in the operative time, blood loss, or length of hospitalization with respect to the approach used. Three patients were converted to open procedures as a result of bleeding from segmental veins. None required transfusions and there were no postoperative sequelae. In two patients, successful endoscopic repair of segmental vein avulsion from the vena cava was performed using endoscopic loop ligatures. One patient had a secondary procedure to remove a cage that was causingnerve irritation, and one patient reported retrograde ejaculation after a two level fusion. Another patient, in whom a posterior herniation was removed, later presented with a cerebrospinal fluid leak. Most of the operative complications occurred early in the series. CONCLUSIONS: Laparoscopic transperitoneal approach to L4-L5 for insertion of threaded fusion cages is feasible. The laparoscopic L4-L5 procedure can be accomplished with few complications, provided a dedicated team of collaborative surgeons with experience in laparoscopic spine techniques is employed. Variations in vascular anatomy did not prevent successful insertion of two threaded fusion cages.

Minimally invasive anterior retroperitoneal approach to the lumbar spine. Emphasis on the lateral BAK.

STUDY DESIGN: Eighteen patients with lumbar instability from fractures, postlaminectomy syndrome, or infection were treated prospectively with minimally invasive retroperitoneal lumbar fusions. OBJECTIVES: To determine if interbody Bagby and Kuslich fusion cages and femoral allograft bone dowels can be inserted in a transverse direction via a lateral endoscopic retroperitoneal approach to achieve spinal stability. SUMMARY OF BACKGROUND DATA: Endoscopic spinal approaches have been used to achieve lower lumbar fusion when instrumentation is placed through a laparoscopic, transperitoneal route. However, complications of using this approach include postoperative intra-abdominal adhesions, retrograde ejaculation, great vessel injury, and implant migration. This study is the first clinical series investigating the use of the lateral retroperitoneal minimally invasive approach for lumbar fusions from L1 to L5. METHODS: Eighteen patients underwent anterior interbody decompression and/or stabilization via endoscopic retroperitoneal approaches. In most cases, three 12-mm portals were used. Two parallel transverse interbody cages restored the neuroforaminal height and the desired amount of lumbar lordosis was achieved by inserting a larger anterior cage, distraction plug, or bone dowel. RESULTS: The overall morbidity of the procedure was lower than that associated with traditional "open" retroperitoneal or laparotomy techniques, with a mean length of hospital stay of 2.9 days (range, outpatient procedure to 5 days). The mean estimated intraoperative blood loss was 205 cc (range, 25-1000 cc). There were no cases of implant migration, significant subsidence, or pseudoarthrosis at mean follow-up examination of 24.3 months (range, 12-40 months) after surgery. CONCLUSIONS: This preliminary study of 18 patients illustrates that endoscopic techniques can be applied effectively through a retroperitoneal approach with the patient in the lateral position. Unlike the patients who had undergone transperitoneal procedures described in previous reports, in these preliminary 18 patients, there were no cases of retrograde ejaculation, injury to the great vessels, or implant migration.

The effect of sensory deprivation in the reduction of pain in patients with chronic low-back pain.

Patients who suffer from persistent pain for prolonged periods of time (6 months or more) are often influenced to an increasing extent by psychological factors. Patients begin to focus on their pain as the problem rather than its physical origin. This study evaluated the effectiveness of sensory deprivation in reducing pain in patients with chronic low-back pain. Sixty patients were divided into two groups of 30 patients each: One group underwent 1 hour of sensory deprivation; the other received a lecture on relaxation skills. In the group receiving sensory deprivation, statistically significant decreases in pain and stiffness were noted. Sensory deprivation is an effective treatment to reduce pain and thus interrupt the pain cycle in patients with chronic low-back pain.

Discitis after discography.

A series of nine patients with post-discography discitis were evaluated to help delineate the clinical course. The most consistent sign was the marked exacerbation of neck or back pain. This then was followed by an elevated sedimentation rate at an average of 20 days, followed by a positive bone scan at an average of 33 days. Of note is that seven patients initially had negative bone scans at an average of 18 days. Five out of nine patients had changes on plain roentgenograms between 14 and 51 days after discography. Magnetic resonance imaging was performed in six patients; two of these patients were scanned twice. Three scans were negative and five were positive (2 patients initially had negative scans that later became positive). The course of lumbar discitis ranged from 8 to 11 weeks, and cervical discitis from 6 to 7 weeks, with the latter usually resulting in spontaneous fusion.

Mediating denials of pharmaceutical services: an alternative to traditional appeals.

The effectiveness of mediation as a primary tool to resolve pharmaceutical service denials by managed care is discussed. A three-month prospective randomized trial of 48 medical appeal cases involving prescription drugs was conducted by Tennessee's Department of Health. Patients whose prescription claims were denied by the state's Medicaid managed care program and whose appeals were deemed medically unnecessary by one of two independent reviewers were randomly assigned to either a standard procedure group or a mediation group. Appeals assigned to the standard procedure group were immediately referred for administrative hearing. In the mediation group, the independent reviewer assigned to the case contacted the patient's care provider, discussed the case, and recommended an alternative drug. The care provider either accepted the suggested compromise, concluding the appeals process, or declined the suggestion, allowing the appeal to go to hearing. Reviewers recorded the amount of time they spent on each appeal. The mediation did not substantially increase the time the reviewers spent on each case (mean +/- S.D. minutes, 15.83+/-7.89 mediation versus 12.26+/-6.96 standard procedure). The mean number of appealed drugs was also similar between groups (1.46+/-0.78 mediation versus 1.35+/-0.89 standard procedure). Only 21% of appealed cases went to hearings in the mediation group, while 80% did in the standard procedure group. The average cost to the state for employing mediation ($142.92+/-$186.77) was significantly lower than the average cost incurred by using standard procedures ($355.75+/-$175.43). Mediation is an effective and efficient tool for resolving patients' appeals of denied pharmaceutical services.

Cervical cord compression from ossification of the posterior longitudinal ligament in non-orientals.

We report 14 cases of symptomatic ossification of the posterior longitudinal ligament (OPLL) diagnosed in non-oriental men between 1978 and 1985. All 14 patients had incomplete spinal cord syndromes due to OPLL in the cervical spine and had been referred undiagnosed from other institutions. Twelve had severe myelopathy and seven were wheelchair-bound before OPLL was diagnosed, while six patients had had operations elsewhere for their neurological dysfunction. There was a close association between OPLL and diffuse idiopathic skeletal hyperostosis (Forestier's disease) on plain radiographs, seven patients having both disorders. Enhanced CT scans proved to be the best diagnostic method for the localisation of cord compression, and magnetic resonance imaging, used on four recent cases, provided the best visualisation of the extent of involvement in the sagittal plane. We aim to heighten awareness of OPLL in non-orientals, in whom the clinical features, histological characteristics, and radiographic patterns are very similar to those of oriental patients.

Percutaneous endoscopic thoracic discectomy.

Video-assisted thoracic surgery (VATS) appears to be a safe and efficacious method of excising herniated thoracic discs. Results indicate high patient satisfaction rates comparable to those of open thoracotomy. VATS' advantages include decreased length of hospitalization, decreased postoperative pain, less shoulder girdle dysfunction, lower incidence of pulmonary complications and post-thoracotomy syndrome, and earlier return to normal activity when compared to thoracotomy approaches.