Search PubMed⌕ Search

Biomedical subjects

J L Cox

Publications and source records attributed to J L Cox.

At least 37 records · Page 2Linked to original sources
PubMed2000

Stroke prevention as an indication for the Maze procedure in the treatment of atrial fibrillation.

The Maze procedure has proven to be extremely effective in curing medically refractory atrial fibrillation. This analysis of our surgical results with the Maze procedure indicates that the Maze procedure, with or without associated cardiac surgery, has the lowest perioperative stroke rate of any major cardiac surgical procedure. This is surprising in view of the fact that all of the patients who undergo the Maze procedure have an elevated risk of stroke because of the presence of atrial fibrillation. In addition, many of the patients have already had strokes, further increasing the likelihood of perioperative stroke. Only 1 patient has had a stroke in the 12-year follow-up period following the Maze procedure. This is comparable to the risk of stroke in the general population and indicates that the Maze procedure essentially abolishes the risk of stroke associated with atrial fibrillation.

Adult↗
PubMed2000

Observations on the perioperative management of patients undergoing the Maze procedure.

In addition to the usual measures that constitute optimal perioperative care after cardiac surgery, the Maze procedure demands several other measures because of certain complications that are unique to this particular operation. These complications include preoperative conditions such as amiodarone therapy, thromboembolism, diastolic dysfunction of the left ventricle, and associated valvular heart disease, as well as intraoperative differences that include multiple atriotomies and excision of both atrial appendages. The most common postoperative complications are atrial arrhythmias, excessive fluid retention, and pulmonary complications. In this article, we outline our own approach to the perioperative care of patients undergoing the Maze procedure.

Atrial Fibrillation↗
PubMed2000

New surgical and catheter-based modifications of the Maze procedure.

There is currently an intense interest in applying the principles of the Maze procedure in a less invasive manner so that a wider group of patients with atrial fibrillation can be treated safely and effectively. These efforts have centered around surgical attempts to curtail the number of lesions placed in the atria at the time of valve surgery and catheter-based attempts to re-create a part or all of the Maze procedure with radiofrequency ablation. Thus far, these techniques remain highly experimental and largely without merit. Many of the problems that we encountered several years ago in developing the surgical Maze procedure are now being repeated in patients undergoing these highly experimental and inadequately evaluated procedures. Nevertheless, there are occasional flashes of promise with some of these approaches. Moreover, it is clear that only a miniscule percentage of the patients with atrial fibrillation will ever become candidates for the open-heart Maze procedure as it is now performed. Therefore, the continuing struggle to relieve the invasive downside of the Maze procedure is warranted but with the caveat, especially to our cardiologist colleagues, to proceed with caution.

Animals↗
PubMed1999

Evaluation of the effect of simulated rainfall on the efficacy of Ivomec Pour-On against Cooperia spp. infection in cattle.

Four controlled studies, one each in Australia, Germany, the United Kingdom, and the United States, involving 30 calves each were conducted to evaluate the effect of simulated rainfall on the efficacy of Ivomec Pour-On against infections of Cooperia spp. At 3 weeks before treatment the calves were infected orally with third-stage larvae of Cooperia spp. In each study a recent, locally derived field isolate was used. The calves were allocated by restricted randomization based on body weight within sex to one of the following treatments: unmedicated control with no rain, Ivomec Pour-On with no rain, Ivomec Pour-On with rain starting at 40 min before treatment, Ivomec Pour-On with rain starting at 10 min after treatment, and Ivomec Pour-On with rain starting at 60 min after treatment. Ivomec Pour-On was applied topically at a dose rate of 1 ml/10 kg body weight (500 microg ivermectin/kg body weight). The simulated rainfall was equivalent to a heavy shower of approximately 12.5 mm of water during a 30-min period. The calves were necropsied for worm counting at 14 or 15 days after treatment. An evaluation of the pooled data showed that as compared with the untreated controls, the Ivomec Pour-On-treated calves with no rain had significantly (P < 0.01) fewer C. oncophora (> 99%), C. punctata (> 99%), C. surnabada (> 98%), and combined Cooperia spp. (> 99%). The reduction in Cooperia numbers noted for calves exposed to simulated rainfall was > 96% for all Cooperia species, regardless of when the rainfall started relative to the application of Ivomec Pour-On. There was no significant (P > 0.1) difference between the Ivomec Pour-On-treated calves with no rain and the pooled groups with simulated rainfall or between the group with rain before treatment and the pooled groups with rain after treatment. Ivomec Pour-On was highly effective against established infections of Cooperia spp. when applied to wet animals or to animals becoming wet shortly after treatment.

Animals↗
PubMed1999

Radial approach: a new concept in surgical treatment for atrial fibrillation I. Concept, anatomic and physiologic bases and development of a procedure.

BACKGROUND: The maze procedure cures atrial fibrillation; however, it isolates the pulmonary vein area and results in discordant activation in certain adjacent left atrial segments, which affects left atrial function. To preserve a more physiologic atrial transport function, we developed a new concept of surgical treatment for atrial fibrillation-the radial approach. The atrial incisions radiate from the sinus node toward the atrioventricular annular margins to allow a more physiologic atrial activation sequence and parallel the atrial coronary arteries to preserve blood supply to most atrial segments. METHODS: We examined the atrial coronary arteries and the activation sequence during sinus rhythm in normal canine hearts to design the atrial incisions according to the concept of a radial approach. RESULTS: The pattern of coronary artery distribution was centripetal, branching from the right coronary or left circumflex coronary artery at the right or left atrioventricular groove and spreading toward the sinus node. The endocardial mapping of the atria disclosed some important findings in designing the atrial incisions of the radial approach: the activation sequence at the left atrial septum and at the posterior left atrium between the pulmonary vein orifices. The atrial incisions were designed according to these findings. CONCLUSIONS: The radial approach may represent a more physiologic atrial transport function.

Animals↗
PubMed1999

Radial approach: a new concept in surgical treatment for atrial fibrillation. II. Electrophysiologic effects and atrial contribution to ventricular filling.

BACKGROUND: In a previous study the atrial incisions that follow the concept of the radial approach were designed according to the activation sequence during sinus rhythm and the atrial coronary artery anatomy in normal dogs. The purpose of the present study was to determine whether the radial approach provides a more physiologic activation sequence and atrial transport function than the maze procedure. METHODS: Ten dogs that had undergone the radial approach (n = 5) or the maze procedure (n = 5) were studied 6 weeks postoperatively. Sinus node function and inducibility of atrial fibrillation were examined before and after operation. The atria were mapped endocardially with 212 electrodes, and atrial activation sequences during sinus rhythm and right atrial pacing were examined. Atrial transport function was assessed by transepicardial Doppler echocardiography. RESULTS: No dogs developed sinus node dysfunction postoperatively. Both the radial approach and the maze procedure equally prevented sustained atrial fibrillation. The atrial activation sequence was more synchronous after the radial approach than after the maze procedure. There was no electrically isolated region after the radial approach. The total activation time of the left atrium was significantly shorter after the radial approach than after the maze procedure (53.6+/-9.8 versus 70.5+/-9.6 ms, p<0.05). The ratio of peak flow velocity of the E wave to the A wave (peak E/A) of the transmitral Doppler flow was significantly smaller after the radial approach than after the maze procedure (1.7+/-0.4 versus 3.5+/-1.7, p<0.05). The atrial filling fraction of the transmitral Doppler flow was significantly larger after the radial approach than after the maze procedure (29.9%+/-7.3% versus 14.8%+/-5.0%, p<0.01). There was no significant difference in peak E/A and atrial filling fraction of the transtricuspid Doppler flow between the two procedures. CONCLUSIONS: The radial approach provides a more synchronous activation sequence and atrial transport function, and thus may represent a more physiologic alternative to the maze procedure as a surgical treatment for atrial fibrillation.

Atrial Fibrillation↗
PubMed1999

The closed heart MAZE: a nonbypass surgical technique.

BACKGROUND: The MAZE-III is the surgical treatment of choice for medically refractory atrial fibrillation. Although a number of nonsurgical techniques are evolving to duplicate the transmural atrial lesions of the MAZE-III, the surgical atriotomy remains the gold standard for conduction block. It was the objective of this study to surgically create the atrial incisions of the MAZE-III without the use of cardiopulmonary bypass. METHODS: A technique was developed to create and intersect the linear incisions of the MAZE-III on 10 beating canine hearts without the use of cardiopulmonary bypass using a "tunnel" of atrial tissue. The effectiveness of the procedure was tested by atrial burst pacing. RESULTS: This technique was successfully performed on 10 mongrel dogs without operative mortality. Preoperatively, sustained atrial fibrillation (>30 seconds) was induced in all animals. Postoperatively, all the animals remained in sinus rhythm even after burst pacing. CONCLUSIONS: In an experimental canine model, the MAZE-III can be performed on beating hearts without the assistance of cardiopulmonary bypass using a "tunnel" technique. This technique allows for the immediate assessment of electrophysiologic and mechanical function after the MAZE-III, or any other type of procedure using the "maze principle" and may find future application in the clinical arena.

Animals↗
PubMed1999

Impact of the maze procedure on the stroke rate in patients with atrial fibrillation.

OBJECTIVE: The incidence of stroke associated with atrial fibrillation, even in high-risk patients, can be reduced significantly by adequate anticoagulation. However, anticoagulation does not abolish the stroke rate, and unfortunately only 40% of patients with atrial fibrillation actually receive anticoagulant therapy, even in areas where adequate health care is available. METHODS: During the past 11.5 years, we have performed the maze procedure for the treatment of medically refractory atrial fibrillation in 306 patients, 58 of whom presented with a history of having had a stroke (n = 40) or transient ischemic attack (n = 18) before surgery. All patients with atrial fibrillation are at an increased risk for these complications, but they are especially prevalent in those patients with previous thromboembolic events and those with other recognized risk factors. RESULTS: Among the 306 patients who had surgery, there were only 2 perioperative strokes (0. 7%), and in the 265 patients followed for up to 11.5 years after the maze procedure, there has been only 1 late minor stroke that has now completely resolved. CONCLUSIONS: The ability of the maze procedure to decrease the risk of stroke associated with atrial fibrillation so dramatically is likely due to the restoring of sinus rhythm and atrial transport function in combination with surgical removal or obliteration of the left atrial appendage, where most thrombi associated with atrial fibrillation develop.

Atrial Appendage↗
PubMed1999

The Edinburgh Postnatal Depression Scale: validation for an Italian sample.

A sample of 113 women has been recruited for the Italian validation of Edinburgh Post Natal Depression Scale (EPDS). These women, between the eighth and the twelfth week after delivery, were admnistered the EPDS and diagnosed according the DSM-III-R criteria using the MINI Interview. At the 8/9 cut-off score the sensitivity is 94.4%, specificity 87.4% and PPV 58.6%. The internal consistency of the EPDS Italian version was tested using Chronbach's alpha coefficient (0.7894) and Guttman split-half coefficient (0.8191). Finally a receiver operating characteristic (ROC) analysis was carried out to evaluate the global functioning of the scale: the area under ROC curve AUC is 0.7470 and the logistic estimate for the threshold score of 11/12 fitted the model sensitivity at 75% and model specificity at 67%. Our data confirm the validity of EPDS in identifying postnatal depression also in its Italian version and the scale could be used as an useful instrument in the clinical practice.

Adult↗
PubMed1999

Echocardiographic characterization of left ventricular diastolic properties in patients presenting for the maze procedure.

The aim of this study is to characterize and compare the left ventricular (LV) diastolic filling patterns in patients with paroxysmal (PAF) versus chronic atrial fibrillation (CAF) undergoing the maze procedure and to examine their relation with the hemodynamic status. Fifty patients with PAF and 22 with CAF were studied. Hemodynamic measurements and transesophageal echocardiography (TEE) were performed after the induction of anesthesia but before surgical incision, at stable conditions. Transmitral (TMF) and pulmonary venous flow (PVF) velocities were recorded with the pulsed Doppler method. Statistical analysis between the two groups (PAF and CAF) was performed using Student's t-test and chi-squared test, with P less than .05 statistically significant. Compared with patients in the PAF group, those in the CAF group had: (1) higher pulmonary capillary wedge pressure (14 +/- 5 v 12 +/- 4 mm Hg; P < .05), (2) lower left ventricular fraction of area change (43% +/- 6% v 52% +/- 9%; P < .01), (3) slower PVF systolic wave velocity (23 +/- 10 v 35 +/- 15 cm/s; P < .05), and (4) lower ratio of PVF systolic to diastolic wave velocity (0.75 +/- 0.3 v 1.2 +/- 0.4; P < .05). In the present study, LV filling patterns of abnormal relaxation were found in all our patients who underwent the maze procedure for CAF or PAF. Although the cause of LV filling abnormalities is not apparent, the data suggest LV diastolic dysfunction is prevalent in these patients.

Adult↗
PubMed1999

A perspective on postoperative atrial fibrillation.

Some patients develop atrial fibrillation after any type of surgery, some patients develop atrial fibrillation only after cardiac surgery, and still other patients never develop postoperative atrial fibrillation. Despite the inherent difficulty in identifying the causes of postoperative atrial fibrillation, several important observations have been made during the recent past that may play a role in treating or even preventing this common and serious postoperative problem. This communication provides a framework within which the problem of postoperative atrial fibrillation can be evaluated and treated.

Atrial Fibrillation↗
PubMed1999

Responsibility and education.

Ethical assumptions of psychiatry training and practice in a postmodern society, and of values and their linked beliefs have become important to search for and to acquire if a psychiatrist is to work in an informed, safe and helpful manner. These educational themes have particularly impacted on mental health services in the past 12 months and are reflected in the publications, including several editorials, reviewed. It is unsurprising that this literature is not evidence based in a restricted sense; but instead the area reviewed is within the field of opinion, purpose of regulatory bodies, and the influence of the public through user groups and the ballot box.

Clinical Competence↗
PubMed1999

Inhibition of B16 melanoma metastasis by overexpression of the cysteine proteinase inhibitor cystatin C.

Progression to metastasis has been correlated with increased cysteine proteinase activity for a number of tumour types. One mechanism of cysteine proteinase regulation in normal cells is by natural protease inhibitors, the cystatins. Here we further characterize a transfected cell line showing increased cystatin C transcription driven by cytomegalovirus (CMV) promoter/enhancer sequences. Properties of this cystatin C altered cell line such as growth in vitro, lung colonization after tail vein injection in mice, production of cystatin, and cysteine proteinase inhibitor activities were examined. Although there was no difference between the growth rate of the cystatin transfected cell line and that of the control, there was a substantial difference in metastatic ability. No increase was noted in cystatin C secretion into the media for the cystatin C transfected cell line compared with the control transfected cell line. There was, however, a difference in cysteine protease inhibitor activity in the cell-free extracts. These results show that alteration of cystatin C levels by overexpression in B16 melanoma alters properties associated with metastasis.

Animals↗
PubMed1999

Induction and maintenance of gastric ulceration in horses in simulated race training.

Gastric ulceration is a prevalent condition of racehorses. A number of models of gastric ulceration have been described, but none mimic the conditions of a horse in training. The objectives of this study were to determine whether gastric ulcers could be induced and maintained in a group of horses in simulated race training. In addition, serum cortisol was measured on a weekly basis to investigate the possibility that stress may be important in the pathogenesis of gastric ulceration. Thirty horses used in the trial were fed Bermuda grass hay and 6 kg of a concentrate diet, and exercised 6 days/week at speed over a distance of 1.6-2.4 km. Serum was collected and gastroendoscopic examinations performed on a weekly basis for the duration of the trial. All horses developed moderate to severe ulceration, and ulcers were maintained for the 56 day period of the trial. Only one horse had signs of abdominal discomfort, which resolved with minimal symptomatic treatment and without the use of anti-ulcer medications. Serum cortisol remained within reference ranges for the duration of the trial. Although there was some variation between the weekly examinations, serum cortisol concentrations were decreased from values obtained at the start of the trial. In this study ulcers developed without the administration of nonsteroidal anti-inflammatory agents or withholding of feed. This model provides a method to study the condition, and to investigate the effects of medications on the healing of ulcers in racehorses.

Analysis of Variance↗
PubMed1999

Safety of omeprazole paste in foals and mature horses.

Omeprazole has been shown to promote healing of spontaneously occurring gastric ulcers in horses when administered for 28 days at a dose of 4 mg/kg bwt/day and to prevent recurrence of ulcers in almost all horses when treatment is continued at a dose of at least 2 mg/kg bwt/day. The purpose of the 3 studies reported here was to 1) evaluate the evolution of potential effects of omeprazole paste (GastroGard), at a dose of 20 mg/kg bwt/day (5x the recommended dose) for 91 days in mature Thoroughbred horses; 2) evaluate the safety in young horses of omeprazole paste when dosed at 4 mg/kg bwt/day (1x), 12 mg/kg bwt/day (3x) or 20 mg/kg bwt/day (5x) for 91 days in Tennessee walking horse foals; and 3) evaluate the safety of omeprazole paste when dosed at 40 mg/kg bwt/day (10x) for 21 days in mature Thoroughbred horses. Within each study, horses were allocated randomly to the control or omeprazole paste treatment group. Clinical examinations, serum biochemistry and haematology were performed at regular intervals until necropsy at the end of the study. There were no treatment-related clinical signs in any treated horse and serum biochemistry and haematology were normal. In conclusion, omeprazole paste is safe for use in horses as demonstrated in studies with foals and mature horses.

Administration, Oral↗
PubMed1999

Safety, acceptability and endoscopic findings in foals and yearling horses treated with a paste formulation of omeprazole for twenty-eight days.

A paste formulation of the H+,K(+)-ATPase inhibitor omeprazole was evaluated in Thoroughbred foals and yearlings for its safety and acceptability. Twenty foals age 11-16 weeks and 20 yearling horses age 15-17 months were included and gastroscopic examinations performed 1-3 days before and at the end of each trial. Lesions were scored on a scale of 0 to 3 and animals allocated based on endoscopic lesion score and sex, with 4 animals in each of 5 replicates. Dosages of 4 mg omeprazole/kg bwt or sham treatment were administered once daily for 28 days, from a syringe graduated in 50 lb (22.68 kg) increments, the amount of paste administered being rounded up to the nearest corresponding weight in pounds. Acceptability of the paste or sham treatment was assessed and recorded by the individual administering the treatment on the basis of the tolerance or resistance to insertion of the syringe into the mouth, administration of the paste and if the paste was swallowed or actively expelled by the animal. Safety was determined on the basis of daily observation recordings and physical examination findings during and at the conclusion of the trial. Treatment was judged to have been accepted for all 420 doses of omeprazole paste and all 140 sham doses given to foals during the trial and for 418/420 doses of paste and all 140 sham doses given to yearlings. Two doses of paste were entirely rejected by yearlings. On the initial endoscopic examination, lesions were observed in the gastric squamous epithelial mucosa in 4 foals and 3 yearlings, and single small, superficial erosions were seen in the gastric glandular mucosa of 2 foals. On the second examination there were small, superficial erosions in the squamous mucosa in 3 foals and 2 yearlings, multi-focal superficial erosions in 1 foal and 1 yearling, and 1 foal had large areas of erosion extending from the margo plicatus toward the dorsal fundus. No lesions in the glandular mucosa were seen in foals or yearlings. There were no significant differences (P < 0.05) in lesion scores between the beginning and the end of the trials in the omeprazole-treated or sham-treated groups of foals or yearlings. A paste formulation of omeprazole, administered at a dose of 4 mg/kg bwt once daily for 28 days, was determined to be highly acceptable to the foals and yearlings we studied, and no adverse effects attributable to the medication were noted.

Administration, Oral↗