Investigating the association between CYP2J2 inhibitors and QT prolongation: a literature review

Drug withdrawal post-marketing due to cardiotoxicity is a major concern for drug developers, regulatory agencies, and patients. One common mechanism of cardiotoxicity is through inhibition of cardiac ion channels, leading to prolongation of the QT interval and sometimes fatal arrythmias. Recently, oxylipin signaling compounds have been shown to bind to and alter ion channel function, and disruption in their cardiac levels may contribute to QT prolongation. Cytochrome P450 2J2 (CYP2J2) is the predominant CYP isoform expressed in cardiomyocytes, where it oxidizes arachidonic acid to cardioprotective epoxyeicosatrienoic acids (EETs). In addition to roles in vasodilation and angiogenesis, EETs bind to and activate various ion channels. CYP2J2 inhibition can lower EET levels and decrease their ability to preserve cardiac rhythm. In this review, we investigated the ability of known CYP inhibitors to cause QT prolongation using Certara's Drug Interaction Database. We discovered that among the multiple CYP isozymes, CYP2J2 inhibitors were more likely to also be QT-prolonging drugs (by approximately 2-fold). We explored potential binding interactions between these inhibitors and CYP2J2 using molecular docking and identified four amino acid residues (Phe61, Ala223, Asn231, and Leu402) predicted to interact with QT-prolonging drugs. The four residues are located near the opening of egress channel 2, highlighting the potential importance of this channel in CYP2J2 binding and inhibition. These findings suggest that if a drug inhibits CYP2J2 and interacts with one of these four residues, then it may have a higher risk of QT prolongation and more preclinical studies are warranted to assess cardiovascular safety.

Echocardiographic prediction of neonatal ECMO outcome

Cardiopulmonary physiology was assessed by Doppler echocardiography in neonates undergoing pre-ECMO evaluation for meconium aspiration syndrome, congenital diaphragmatic hernia, persistent fetal circulation, and sepsis, from March 1987 through July 1992 (n = 136). Percent survival by diagnosis was: meconium aspiration syndrome, 86%; persistent fetal circulation, 68%; congenital diaphragmatic hernia, 63%; sepsis, 33%. Survival odds by diagnosis predicted a better outcome for meconium aspiration syndrome than for congenital diaphragmatic hernia and sepsis, and a better outcome for persistent fetal circulation than for sepsis. Percent survival for right-to-left patent ductus arteriosus flow (PDA) was 56%; other patent ductus arteriosus flow was 84%. In multivariate analysis, percent survival in congenital diaphragmatic hernia and persistent fetal circulation patients with right-to-left PDA flow suggested a worse outcome (% survival right-to-left vs other: congenital diaphragmatic hernia, 13% vs 70%; persistent fetal circulation, 25% vs 85%), whereas percent survival did not appear to suggest the same in meconium aspiration syndrome or sepsis patients. Similar analysis in non-ECMO patients suggested a worse outcome with right-to-left PDA flow in patients with meconium aspiration syndrome and congenital diaphragmatic hernia. Right-to-left PDA flow, sepsis, and congenital diaphragmatic hernia were associated with a poorer ECMO outcome. Initial assessment of PDA flow helps predict ECMO outcome.

Arthroscopic appearance of frozen shoulder

Patients (n = 150) were referred to a shoulder clinic with a diagnosis of "frozen shoulder" and the suggestion that they be submitted to manipulation. All patients were further investigated using local anesthetic blocks, routine radiography, and, often, computed tomographic scanning and arthrograms. Subsequently, it appeared that only 37 patients qualified for the diagnosis of "primary" frozen shoulder. The others had a "secondary" frozen shoulder from some other painful cause, such as a rotator cuff tear or impingement. The 37 patients were arthroscoped and then manipulated while under general anesthesia. Patients were told that both irrigation and local injection of the joint would have an additional beneficial therapeutic effect in the recovery phase, and they gave prior consent to the procedures. There were no complications. Pain relief was striking. The arthroscopic appearance was uniform: a patchy vascular reaction around the biceps, and the opening into the subscapularis bursa. The capacity of the joint was reduced. In no patient was the infraglenoid recess obliterated, and no adhesions were seen. Such findings at routine shoulder arthroscopy should alert the surgeon to a diagnosis of frozen shoulder if the clinical presentation has been subtle. The findings raise questions about the previous pathological interpretation of this condition.

Primary chest wall tumor appearing as frozen shoulder. Review and case presentations

The term frozen shoulder may apply to a primary, common, recognizable entity with a predictable course to a painful stiff condition with periarthritis secondary to trauma, rotator cuff or arthritic source. We studied 140 cases of frozen shoulder, referred to a surgical clinic for manipulation when conservative care was not effective. Investigations showed only 40 cases had "primary" frozen shoulder and among these were 3 patients with a local primary invasive neoplasm mimicking the exact features of the common condition. The attending physician and surgeon should be suspicious of tumor in younger patients with progressive pain among the other features of primary frozen shoulder.

Superior humeral dislocation. A complication following decompression and debridement for rotator cuff tears

Very large rotator cuff tears may be surgically irreparable and under such circumstances debridement of the edges of the cuff and bursal decompression may relieve pain. In this paper, four cases are described of the development of superior migration of the humeral head following a debridement and bural decompression. In all four patients attempts were made to repair the rotator cuff. In each case the repair failed and the humeral head migrated. Two of the patients had the humeral head replaced because of a fracture; in these patients the prosthesis displaced upwards. This serious complication may follow debridement and release of the subacromial bursa when rotator cuff repair cannot be achieved. In the correction of superior humeral migration, reestablishment of the roof of the bursa was carried out in two cases. This procedure appears effective and may be considered in the future for such cases.

Failed acromioplasty for impingement syndrome

We evaluated 67 shoulders in 65 patients who had pain and dysfunction for more than two years after an initial acromioplasty for impingement syndrome without a rotator cuff tear. In addition to a thorough history, physical examination, local anaesthesia injection and any other necessary investigations all patients had arthroscopic evaluation of the shoulder. In 27 shoulders there had been diagnostic errors, and in 28 operative errors; only in 12 had the diagnosis and the operative procedure both been correct. Subsequent operative intervention in patients not receiving worker's compensation benefit had a 75% success rate, whereas in those receiving such benefits the success rate was only 46%.

Arthroscopy for shoulder instability and a technique for arthroscopic repair

At this time the principal role of the arthroscope in the management of dislocating shoulder seems to be the identification of the intra-articular pathology. The findings should enable a surgeon to carry out an appropriate open repair, and the results of such surgery are excellent. Is there a place for arthroscopic repair? Some patients sometimes request it; others have had a failed open repair, or wish to avoid a scar. The author has devised a removable "Rivet," which fixes a loose labrum and the inferior glenohumeral ligament back on to a roughened glenoid margin. Use of this technique avoids some of the hazards that occur with implanting a staple or similar device in the joint. The "Rivet" is removed after 4-6 weeks. Ten patients have been so treated, with a follow-up of 6 months to 2 years. There was one failure, with a return of dislocation.

Arthroscopic shoulder surgery

Arthroscopy has proven to be a very important orthopaedic tool for treatment of the knee and other joints. Since 1972, we have used the arthroscope to examine the interior of shoulder joints. We prefer to perform arthroscopy while the patient is under general anaesthesia, as local anaesthetic may result in unnecessary patient discomfort and there can be difficulty in distracting and rotating the humerus. Arthroscopic operative procedures include the inspection of a torn glenoid labrum and certain lesions of the biceps tendon, viewing a torn rotator cuff, locating loose bodies in the shoulder, surgery for recurrent dislocations, and division of the coracoacromial ligament.

Researches in orthopedic wound infection

The roles of personnel, clean air, and the patient in the contamination of clean orthopedic wounds have been investigated over a three-year period. Personnel control showed striking decreases in operative infection rates. Wound cultures failed to show specific routes of infection. Microspheres were useful tracers for contamination of a clean air operating room and indicated that residual wound contamination occurred from surgical personnel or from the patient's skin.

Percutaneous bone marrow grafting of fractures and bony defects. An experimental study in rabbits

Since bone marrow has been shown to contain osteoprogenitor cells, an experiment was devised to test its effects when injected percutaneously into osteotomies and 2-cm bony defects produced in rabbit radii. The parameters tested included callus volume, breaking load, tensile strength, and cross-sectional area of callus at the fracture or bony defect site. At two weeks postgrafting callus volume was significantly higher (p less than 0.01) in the grafted radii than in the contralateral saline controls. By four weeks all four parameters were significantly greater in the bone marrow grafted radii than in the contralateral saline controls. Serial radiographs and histology confirm this advanced fracture healing in the grafted bones. The earlier and more abundant callus, at the bone marrow grafted sites, was felt to provide earlier and greater stability, resulting in decreased early healing time when contrasted with the saline controls. Similarly, the bony defects that were grafted with bone marrow united by a bony bridge, whereas the saline controls did not. Percutaneous bone marrow grafting is a simple semi-invasive technique that may have potential clinical applications.

Arthroscopic surgery of the shoulder. A general appraisal

Arthroscopic surgery of the shoulder was performed on 439 patients over a 10-year period: these patients are reviewed after a minimum follow-up of one year. Diagnostic arthroscopy is known to be valuable and we have found that arthroscopic surgery also is safe and effective. It was useful in treating frozen shoulder, early osteoarthritis, isolated tears of the glenoid labrum and lesions of the biceps tendon. It was less useful in treating partial tears of the rotator cuff, tendonitis and severe osteoarthritis, and of little value in treating complete tears of the rotator cuff or in treating patients in whom previous operations on the rotator cuff had failed. It may prove to be a useful method of performing synovectomy in rheumatoid arthritis and of treating instability.

Post-traumatic dystrophy of the extremities

A series of 126 patients who had post-traumatic dystrophy of the hand and foot, with a follow-up of more than five years in most, is described. Nearly all had continuing symptoms and signs. An additional twenty-seven patients, with twenty-eight involved extremities, who were referred from various hospitals in Toronto were treated with one or more intravenous injections of a solution of lidocaine and corticosteroid followed by standard physical therapy. The results were satisfactory or better in twenty-one extremities and poor in seven. Of the twenty-one with a satisfactory result, eleven (six patients with involvement of the hand, bilateral in one, and four patients with involvement of the foot) had an excellent result while the other ten showed substantial improvement. The most important factor in predicting improvement with treatment was a short interval (less than six months) between the onset of dystrophy and the administration of therapy.

Shoulder impingement syndrome. Results of operative release

For the release of mechanical impingement occurring during the movement of the humeral head and its overlying rotator cuff beneath the coracoacromial arch, 21 patients who had a painful arc resistant to conservative treatment, were treated by subacromial recession operations. The procedure consisted of resection of the coracroacromial ligament, anterior acromioplasty, excision of the acromioclavicular joint and shaving of the greater tuberosity. Resection of the coracoacromial ligament was carried out in all patients. The other procedures were added when required for complete release of the impingement. Nineteen patients obtained satisfactory results with a minimum follow-up of one year. A satisfactory result was obtained only when the operative procedure relieved the specific mechanical impingement, i.e., coracoacromial ligament, acromial spur, osteoarthritic acromioclavicular joint or exuberant greater tuberosity.

Advancement of the supraspinatus muscle in the repair of ruptures of the rotator cuff

In ruptures of the rotator cuff, the supraspinatus tendon frequently is retracted and repair without excessive tension is difficult to achieve. The technique of supraspinatus advancement, as described by Debeyre et al., may be a useful technique for such patients. We reviewed the results of this operation in eighteen patients seen by us. In fourteen (77 per cent) of them satisfactory results were obtained after a minimum follow-up of two years. Meticulous technique and preservation of the neurovascular supply of the supraspinatus tendon enhanced the outcome. An approach to the supraspinatus muscle utilizing resection of the acromioclavicular joint facilitated the repair.

"Supraspinatus slide" for rotator cuff repair

The supraspinatus slide procedure described by Debeyre et al. (1965) offers an opportunity for the surgeon to repair certain large and late ruptures of the rotator cuff. In order to re-appraise this procedure and clarify its indications, the authors performed the following study: Firstly 37 rotator cuff ruptures repaired by this method were reviewed. Most of the patients were supplied by the Workmen's Compensation Board of Ontario. The review period was from 1968 to 1977. Secondly, the surgical anatomy of the area was reviewed. Twenty-two (60%) of the patients obtained satisfactory results. They were relieved of pain, gained functional improvement and returned to their previous or a modified occupation. Although the vulnerability of the suprascapular nerve and artery was demonstrated in anatomical dissections, no neurological sequelae were noted and the muscle remained viable in all patients. Electro-myographical studies failed to show supraspinatus muscle denervation in any case. The procedure proved to be useful in the repair of large rotator cuff ruptures that are not amenable to other methods of repair. A young well motivated patient with chronic disability may benefit from this procedure.

An extensile exposure for subacromial derangements

To allow adequate access to the subacromial region of the shoulder the authors designed a multipurpose approach. The exposure consists of an anterior and a posterior part. In the anterior part, the deltoid fibres are separated between the anterior and middle thirds form the acromioclavicular joint for 5 cm distally; this provides the required access for the management of impingement syndrome, calcific tendinitis, bicipital tendon lesions and most tears of the rotator cuff. By extending the anterior part of the incision posteriorly over the supraspinatus muscle, this muscle may be advanced laterally for closure of a large tear. With this approach, osteotomy of the acromion or detachment of the deltoid muscle is avoided so that the integrity of the deltoid mechanism is maintained.

High tibial osteotomy combined with joint debridement: a long-term study of results

Combined high tibial osteotomy and joint debridement have been performed in the treatment of unicompartmental osteoarthritis of the knee. A specially designed angled compression plate was used for fixation after a wedge upper tibial resection, and this permitted early joint motion and eliminated cast immobilization. Knee stiffness was thereby prevented. The adjunctive joint debridement enabled us to remove torn menisci, loose bodies and marginal osteophytes. Seventy-one patients were operated upon between 1966 and 1978. An average follow-up period of six years was recorded. Critical analysis of the results showed a satisfactory rate of 83%. This rate appeared to justify the rationale of the procedure, which is based on a belief that intra-articular pathology is responsible for the symptoms and that the deformity is secondary. Comparison with results of tibial osteotomy alone are favorable. The durability of results compares well with that of joint replacement.

Total hip replacement in a laminar flow environment with special reference to deep infections

A clean air enclosure with standard drapings was inadequate in the prevention of deep infection in total hip replacement and an overall deep infection rate of 2.2% still existed. This suggested that a sterile atmosphere under these circumstances could not ensure a bacteria-free deep wound at the end of a lengthy procedure. Additional antibiotic coverage, however, gave a deep wound infection rate of zero. A larger number of cases must be studied before final conclusions can be reached. Subsequent studies under these conditions have shown that the contamination appears to come from both patient and surgeon--principally the latter. Patient-derived organisms can be eliminated by impermeable draping. Contamination from the surgeon possibly can be eliminated only by drastic modification of conventional surgical attire.

Shoulder arthroscopy. Investigations with a fibreoptic instrument

Ten patients with frozen shoulders and 13 other patients with derangements of the shoulder were examined by arthroscopy. The procedures were performed under anesthesia. A fibreoptic instrument was introduced posteriorly. All patients with frozen shoulders were relieved of their symptoms by the combined procedure of joint distention (with as much as 60 ml of saline) and arthroscopy, with or without manipulation of the shoulder. Three of the 13 cases of imprecisely diagnosed shoulder derangement are described in detail to illustrate refinements in the diagnosis which determined surgical repair in 2 cases and precise local treatment in the other one. All patients, whose shoulders were not manipulated, were discharged to their homes on the day of the procedures. A sling was worn for the first 24 hr and then the patient was placed on a regimen of supervised physical therapy. There was no significant morbidity in these patients. Additional refinements in arthroscopy for the shoulder and increasing expertise in using the techniques will firmly establish arthroscopy as a means for establishing precise diagnoses fro shoulder conditions.

Aspirin prophylaxis of venous thromboembolic disease following fracture of the upper femur

In a prospective study of 51 patients with fractures of the femoral neck, aspirin was used as a prophylactic measure against thromboembolic disease. Thrombi were detected by cuff impedence plethysmography, Doppler ultrasonography and ascending venography. Thrombi were identified in 20 (39.2%) of the patients. There was no significant difference between the frequency with which thrombi occurred in men and in women. Blood salicylate values were the same for patients who had and who did not have thrombi. There were no instances of pulmonary embolism. The frequency of deep vein thrombosis was comparable to that in a previous series of untreated patients from the same centre. It appears from this study that in these cases prophylaxis against venous thromboembolism using aspirin in a dosage of 600 mg bid is ineffective.

Routes of infection. A study of using "tracer particles" in the orthopedic operating room

Wound irrigates and tissue samples were cultured from clean orthopedic wounds at the conclusion of 280 orthopedic operations. The surgeons used a laminar flow unit and took extra precautions against wound contamination although personnel exhaust systems were not used. It was possible to culture residual organisms but difficult to trace the source of these by bacteriological methods. Artificial or "tracer" particles which could be applied to patient or surgeon were retrieved from the wound and suitably stained. Using albumin microspheres it was possible to identify and differentiate "patient-derived particles" from "surgeon-derived particles" in the majority of all wounds. Contamination from the surgeon was significant even under near optimum operating room conditions. These techniques are useful for development of control measures for residual wound contamination in orthopedic operating rooms.