Biomedical subjects
J J Collins
Publications and source records attributed to J J Collins.
Noise-enhanced tactile sensation.
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Predictors of atrial fibrillation after coronary artery surgery. Current trends and impact on hospital resources.
BACKGROUND: Atrial fibrillation (AF) after coronary artery bypass surgery (CABG) is the most common sustained arrhythmia. Its pathophysiology is unclear, and its prevention and management remain suboptimal. The aim of this prospective study was to determine the current incidence of AF, identify its clinical predictors, and examine its impact on resource utilization. METHODS AND RESULTS: Over a 12-month period ending July 31, 1994, a CABG procedure was performed on 570 consecutive patients (age range, 32 to 87 years; median age, 67 years; 232 [41%] were > or = 70 years; 175 [31%] were women; 173 [30%] were diabetics; 364 [65%] required nonelective surgery; 86 [15%] had had a prior CABG; and 86 [15%] had had prior percutaneous transluminal coronary angioplasty). AF occurred in 189 patients (33%). The median age for patients with AF was 71 years compared with 66 for patients without (P = .0001). Multivariate logistic regression analysis (odds ratio, +/- 95% CI, P value) was used to identify the following independent predictors of postoperative AF: increasing age (age 70 to 80 years [OR = 2; CI, 1.3 to 3; P = .002], age > 80 years [OR = 3; CI, 1.6 to 5.8; P = .0007]), male gender (OR = 1.7; CI, 1.1 to 2.7; P = .01), hypertension (OR = 1.6; CI, 1.0 to 2.3; P = .03), need for an intraoperative intraaortic balloon pump (OR = 3.5; CI, 1.2 to 10.9; P = .03), postoperative pneumonia (OR = 3.9; CI, 1.3 to 11.5; P = .01), ventilation for > 24 hours (OR = 2; CI, 1.3 to 3.2; P = .003), and return to the intensive care unit (OR = 3.2; CI, 1.1 to 8.8; P = .03). The mean length of hospital stay after surgery was 15.3 +/- 28.6 days for patients with AF compared with 9.3 +/- 19.6 days for patients without AF (P = .001). The adjusted length of hospital stay attributable to AF was 4.9 days, corresponding to > or = $10 055 in hospital charges. CONCLUSIONS: AF remains the most common complication after CABG and consequently is a drain on hospital resources. Concerted efforts to reduce the incidence of AF and the associated increased length of stay would result in substantial cost saving and decrease patient morbidity.
Long-term follow-up after surgical repair of ostium primum atrial septal defects in adults.
OBJECTIVES: We sought to determine the long-term survival rates and defect-related morbidity of adult patients who undergo surgical repair of an ostium primum atrial septal defect. BACKGROUND: The natural history of patients undergoing such surgical repair in adulthood remains unclear. METHODS: We followed up 33 patients who underwent surgical correction of an ostium primum atrial septal defect at our institution at a mean age of 42 years (range 20 to 73); 12 of these patients were > 50 years old at the time of operation. Four patients had moderate preoperative exercise incapacity (New York Heart Association functional class > II) and six had atrial fibrillation. Nine and four patients, respectively, had a preoperative mean pulmonary artery pressure > 25 mm Hg or pulmonary vascular resistance > 4 Wood U. Autologous pericardium was used to patch the defect in 30 patients (91%). Mitral valvuloplasty, consisting of cleft repair (n = 10), and mitral valve replacement (n = 2) were performed selectively. RESULTS: There were no operative deaths. At a mean follow-up interval of 5.3 years (range 1 to 18.2), all 28 surviving patients are free of exercise limitation (functional class 1). Late postoperative deaths occurred in five patients (15%) and were related to myocardial infarction, stroke, hepatic failure, renal failure or sepsis. Reoperation within the 1st postoperative year was required in two patients (6%) because of a residual ostium primum defect in one and severe mitral regurgitation in the other. The presence of advanced age at operation, symptoms, atrial arrhythmias, mitral regurgitation or moderately increased pulmonary vascular resistance did not predict late postoperative mortality, complications or functional capacity. CONCLUSIONS: An ostium primum defect can be repaired in adult patients with the expectation of excellent long-term results, independent of age at operation and preoperative mitral valve function and despite the presence of atrial fibrillation or moderately elevated pulmonary vascular resistance.
Current incidence and determinants of perioperative myocardial infarction in coronary artery surgery.
Increasingly, patients undergoing coronary artery bypass grafting (CABG) are elders, have had previous CABG, and have poor left ventricular function. To evaluate determinants of perioperative myocardial infarction (PMI) after isolated CABG, 499 consecutive patients were reviewed. Definite PMI (total peak creatine kinase [CK] > 700 U/L, creatine kinase MB [CK-MB] > 30 ng/ml, and new pathologic electrocardiographic Q waves) occurred in 25 patients (5.0%) and probable PMI (total peak CK > 700 U/L, CK-MB > 30 ng/ml, and a new wall-motion abnormality) occurred in 10 (2.0%) patients. According to multivariate logistic regression analysis, independent risk factors for definite or probable PMI (adds ratios; 95% confidence intervals) were emergency surgery (3.1; 1.1 to 8.4; p = 0.003), aortic cross-clamp time > 100 minutes (4.2; 1.6 to 11.2; p = 0.004), myocardial infarction in the preceding week (2.6; 1.0 to 6.4; p = 0.04), and previous revascularization (2.4; 1.1 to 5.2; p = 0.02). In conclusion, both preoperative and intraoperative factors influence the risk of PMI after CABG. Despite changes in the profile of patients undergoing CABG, the incidence of PMI in this tertiary center is comparable with that found in earlier series, probably because of improvements in surgical techniques and postoperative care.
Patient-controlled analgesia for mucositis pain in children: a three-period crossover study comparing morphine and hydromorphone.
OBJECTIVES: (1) To test the safety and efficacy of a clinical protocol for administering opioid by using patient-controlled analgesia (PCA) for the management of mucositis pain in children after bone marrow transplantation, (2) to compare the efficacy, side-effect profile, and potency ratio of morphine with those of hydromorphone by using PCA as the method of opioid administration, and (3) to obtain pharmacokinetic data on hydromorphone and morphine in this population of children. METHODS: In this double-blind, three-period crossover study, patients were randomly assigned to receive either morphine (group 1) or hydromorphone (group 2) initially by means of PCA on days 1, 2, and 3 (period 1), to be followed on days 4, 5, and 6 (period 2) with the alternative opioid, followed by the opioid used at the commencement of the study on days 7, 8, and 9 (period 3). A clinical protocol for calculating the PCA commencement opioid dose and subsequent opioid-dose escalation was tested by measures of safety and efficacy. Measures of pain intensity and opioid side effects were made during the three periods. On the last study day (day 10), patients received a continuous infusion of opioid derived from the previous 24-hour PCA opioid requirement, and blood specimens were collected and stored for subsequent opioid analysis. RESULTS: Ten patients were enrolled in this study. Rapid escalation in opioid requirement commonly occurred at the commencement of PCA, followed by a variable plateau phase and then deescalation of opioid requirement after mucositis resolution. The measures demonstrated the safety and efficacy of the clinical protocol. In the concentrations used, there was no statistical difference between the mean daily pain, sedation, nausea and vomiting, and pruritus scores for both opioids (Friedman test). The analysis of variance of the log-total opioid doses per patient during periods 1, 2, and 3 indicated that patients used 27% more hydromorphone than expected from its presumed 7:1 ratio relative to morphine potency used in the PCA infusions. The mean plasma hydromorphone concentration was 4.7 ng/ml (range, 1.9 to 8.9 ng/ml), and the mean clearance was 51.7 ml/min per kilogram of body weight (range, 28.6 to 98.2 ml/min per kilogram). The mean plasma morphine, morphine-6-glucuronide, and morphine-3-glucuronide concentrations were 40.0 ng/ml (range, 15 to 62.5), 168.2 ng/ml (range, 54.4 to 231.9), and 391.0 ng/ml (range, 149.4 to 921.7), respectively. The mean morphine clearance was 34.3 ml/min per kilogram of body weight (range, 19.3 to 58.3). The mean molar ratios of morphine-6-glucuronide/morphine, morphine-3-glucoronide/morphine, and morphine-3-glucuronide/morphine-6-glucuronide were 2.48 (range, 1.4 to 3.3), 5.82 (range, 3.4 to 9.1), and 2.46 (range, 1.1 to 3.3), respectively. CONCLUSIONS: The safety and efficacy of a clinical protocol for the administration of opioids by means of PCA for mucositis pain after bone marrow transplantation was demonstrated. In this small study, hydromorphone was not superior to morphine in terms of analgesia or the side-effect profile: a larger study would be needed to show a difference. The clearances of hydromorphone and morphine in the children studied were generally greater than those previously recorded, but this finding may be related to disease or treatment variables. Apart from clearance, the morphine pharmacokinetics in the study population were similar to those previously recorded. Hydromorphone may be less potent in this population of children than indicated by adult equipotency tables.
Comparison of oral cefuroxime axetil and oral amoxycillin/clavulanate in the treatment of community-acquired pneumonia.
Cefuroxime axetil has been evaluated previously in the treatment of lower respiratory tract infections, but not specifically in the treatment of community-acquired pneumonia. In a multicentre, investigator-blinded clinical trial, 162 patients with community-acquired pneumonia were randomly assigned to receive orally either cefuroxime axetil 500 mg bid (n = 84) or amoxycillin/clavulanate 500 mg/125 mg tid (n = 78) for 10 days. Organisms were isolated from the pretreatment sputum specimens of 97 of 162 (60%) patients, the commonest isolates being Streptococcus pneumoniae (38%) and Haemophilus influenzae (18%). A satisfactory clinical outcome (cure or improvement) was achieved in 100% (55 of 55) and 96% (49 of 51) of the clinically evaluable patients treated with cefuroxime axetil or amoxycillin/clavulanate, respectively (P = 0.23). With respect to eradication of bacterial pathogens, a satisfactory outcome (cure, presumed cure or cure with colonization) was obtained in 94% (32 of 34) and 93% (37 of 40) of bacteriologically evaluable patients treated with cefuroxime axetil or amoxycillin/clavulanate, respectively (P = 1.00). Both treatment regimens used in this study were well tolerated. The most common drug-related adverse experiences were gastrointestinal events, reported by 8% and 4%, respectively, of the patients in the amoxycillin/clavulanate and cefuroxime axetil groups, a difference which was not statistically significant (P = 0.32). These results indicate that cefuroxime axetil twice a day is as effective as amoxycillin/clavulanate three times a day in the treatment of outpatients with mild to moderate community-acquired pneumonia.
Effectiveness of five days of therapy with cefuroxime axetil suspension for treatment of acute otitis media.
BACKGROUND: In recent years there has been considerable interest in reducing the duration of antibiotic treatment regimens in patients with common bacterial infections. We conducted two independent, investigator-blinded, multicenter, randomized clinical trials, one of which included microbiologic evaluation of middle ear fluid obtained by tympanocentesis, comparing the efficacy and safety of 5 or 10 days of treatment with cefuroxime axetil suspension (CAE) with that of 10 days of treatment with amoxicillin/clavulanate suspension (AMX/CL) in children with acute otitis media. METHODS: A total of 719 pediatric patients from the ages of 3 months to 12 years were enrolled in the 2 studies. Patients received CAE for either 5 or 10 days at 30 mg/kg/day in 2 divided doses (n = 242 and 235, respectively) or AMX/CL for 10 days at 40 mg/kg/day in 3 divided doses (n = 242). Patients in the CAE (5 days) group received placebo on Days 6 through 10. In the study that included tympanocentesis, bacteriologic assessments were based on middle ear fluid cultures obtained pretreatment and, when possible, after treatment in patients with an unsatisfactory clinical outcome. RESULTS: Organisms were isolated from the pretreatment middle ear fluid specimens of 177 of 244 (73%) patients undergoing tympanocentesis, with the primary pathogens being Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis (37, 35 and 12% of isolates, respectively). Pathogens were eradicated or presumed to be eradicated in 92% (24 of 26), 84% (32 of 38) and 95% (36 of 38) of bacteriologically evaluable patients treated with CAE for 5 or 10 days or with AMX/CL, respectively. A satisfactory clinical outcome (cure or improvement) occurred in 69% (101 of 147), 70% (121 of 173) and 74% (131 of 177) of clinically evaluable patients treated with CAE (5 days), CAE (10 days) or AMX/CL, respectively. Treatment with AMX/CL was associated with a significantly higher incidence of drug-related adverse events than was treatment with CAE for either 5 or 10 days (P < 0.001), primarily reflecting a higher incidence of drug-related gastrointestinal adverse events (34% vs. 17 and 12%, respectively; P < 0.001), particularly diarrhea. CONCLUSIONS: Treatment with CAE given twice daily for 5 days is equivalent to treatment for 10 days either with the same regimen of CAE or with AMX/CL given three times daily in pediatric patients with acute otitis media.
Comparison of single-dose cefuroxime axetil with ciprofloxacin in treatment of uncomplicated gonorrhea caused by penicillinase-producing and non-penicillinase-producing Neisseria gonorrhoeae strains.
A randomized, multicenter, investigator-blind trial was conducted to compare the efficacies of cefuroxime axetil and ciprofloxacin for treatment of patients with uncomplicated gonorrhea caused by penicillinase-producing Neisseria gonorrhoeae (PPNG). A total of 832 patients (434 females and 398 males) received a single oral dose of cefuroxime axetil (1,000 mg [417 patients]) or ciprofloxacin (500 mg [415 patients]). N. gonorrhoeae was eradicated from the cervix in 114 of 118 (97%) and 118 of 119 (99%) bacteriologically evaluable females treated with cefuroxime axetil and ciprofloxacin, respectively (P = 0.213; difference, -2%; 95% confidence interval, -6 to 1%), and from the urethra in 154 of 166 (93%) and 171 of 171 (100%) bacteriologically evaluable male patients treated with cefuroxime axetil and ciprofloxacin, respectively (P < 0.001; difference, -7%; 95% confidence interval, -11 to -3%). Both treatments were effective in eradicating N. gonorrhoeae in females with rectal infections (cefuroxime axetil, 29 of 30 [97%]; ciprofloxacin, 25 of 25 [100%]; P = 1.00). In small numbers of patients, cefuroxime axetil was less effective than ciprofloxacin in treating males with pharyngeal infections (eradication in 4 of 10 and in 8 of 8 patients, respectively; P = 0.013). PPNG was eradicated from the cervix in 22 of 23 (96%) and 32 of 32 (100%) bacteriologically evaluable female patients treated with cefuroxime axetil and ciprofloxacin, respectively (P = 0.418; difference, -4%; 95% confidence interval, -13 to 4%), and from the urethra in 35 of 36 (97%) and 34 of 34 (100%) bacteriologically evaluable male patients treated with cefuroxime axetil and ciprofloxacin, respectively (P = 1.00; difference, -3%; 95% confidence interval, -8 to 3%). The incidences of drug-related adverse events were similar for the two study drugs. In summary, treatment with a single oral dose of cefuroxime axetil is as effective as treatment with a single oral dose of ciprofloxacin in eradicating PPNG from males and females with uncomplicated gonorrhea (urethral and endocervical), and both regimens are well-tolerated. However, in the present study, cefuroxime axetil was less effective than ciprofloxacin in treating urethral gonococcal infections in male patients, although both study drugs were highly effective in treating cervical gonococcal infections in female patients.
Noise-enhanced information transmission in rat SA1 cutaneous mechanoreceptors via aperiodic stochastic resonance.
1. Aperiodic stochastic resonance (ASR) is a phenomenon wherein the response of a nonlinear system to a weak aperiodic input signal is optimized by the presence of a particular, nonzero level of noise. Our objective was to demonstrate ASR experimentally in mammalian cutaneous mechanoreceptors. 2. Experiments were performed on rat slowly adapting type 1 (SA1) afferents. Each neuron was subjected to a perithreshold aperiodic stimulus plus noise. The variance of the noise was varied between trials. The coherence between the aperiodic input stimulus and the response of each SA1 afferent was computed. 3. Of the 12 neurons tested, 11 showed clear ASR behavior: as input noise variance was increased, the stimulus-response coherence rapidly increased to a peak and then slowly decreased. These findings were in contrast with those for the average firing rate, which increased monotonically as a function of input noise variance. 4. This work shows that noise can serve to enhance the response of a sensory neuron to a perithreshold aperiodic input signal. These results suggest a possible functional role for input noise in sensory systems. These findings also indicate that it may be possible to introduce noise artificially into sensory neurons to improve their abilities to detect arbitrary weak signals.
Evaluation of mortality and cancer incidence among alachlor manufacturing workers.
Alachlor is the active ingredient in a family of preemergence herbicides. We assessed mortality rates from 1968 to 1993 and cancer incidence rates from 1969 to 1993 for manufacturing workers with potential alachlor exposure. For workers judged to have high alachlor exposure, mortality from all causes combined was lower than expected [23 observed, standardized mortality ratio (SMR) = 0.7, 95% CI, 0.4-1.0], cancer mortality was similar to expected (6 observed, SMR = 0.7, 95% CI, 0.3-1.6), and there were no cancer deaths among workers with 5 or more years high exposure and 15 or more years since first exposure (2.3 expected, SMR = 0, 95% CI, 0-1.6). Cancer incidence for workers with high exposure potential was similar to the state rate [18 observed, standardized incidence ratio (SIR) = 1.2, 95% CI, 0.7-2.0], especially for workers exposed for 5 or more years and with at least 15 years since first exposure (4 observed, SIR = 1.0, 95% CI, 0.3-2.7). The most common cancer for these latter workers was colorectal cancer (2 observed, SIR 3.9, 95% CI, 0.5-14.2 among workers). Despite the limitations of this study with respect to small size and exposure estimating, the findings are useful for evaluating potential alachlor-related health risks because past manufacturing exposures greatly exceeded those characteristic of agricultural operations. These findings suggest no appreciable effect of alachlor exposure on worker mortality or cancer incidence rates during the study period.
Reduced mortality and morbidity for ascending aortic aneurysm resection regardless of cause.
BACKGROUND: This study was done to answer the question, "What is the current risk of resection of ascending aortic aneurysms regardless of acuity or cause?" METHODS: One hundred fifteen consecutive patients who underwent ascending aortic aneurysm repair from January 1, 1990, to July 1, 1995, were retrospectively reviewed, excluding those with acute ascending aortic dissection. The mean age was 59 years; 55% were male. Concomitant procedures included coronary artery bypass in 23 (20%) and arch repair in 12 (10%). In group 1, 54 patients had replacement of the aortic valve, root, and ascending aorta with a valve-graft conduit using the "Bentall" technique, and of these 19 (35%) had Marfan's syndrome. In group II, 44 patients had separate aortic valve repair or replacement and supracoronary ascending aortic replacement. In group III, 17 patients had supracoronary ascending aortic replacement, without aortic valve operation. Operative techniques included frequent use of (1) intraoperative transesophageal echocardiography or epiaortic ultrasound scanning of the ascending and descending thoracic aorta to help guide arterial cannulation, avoid atherosclerotic embolization, and assess the repair; (2) antegrade and retrograde multidose cold blood cardioplegia for myocardial protection; (3) exclusion and button anastomotic techniques to ensure secure suture lines; (4) antifibrinolytic agents and collagen-impregnated aortic grafts to reduce bleeding; and (5) deep hypothermic circulatory arrest and the open distal anastomotic technique in patients with distal ascending and arch aortic disease. RESULTS: Operative mortality overall was 2/115 (1.7%). Mortality was 1/54 (1.8) in group I and 1/44 (2%) in group II, and there was no mortality in group III. The overall postoperative morbidity was 3% due to bleeding, 2% due to stroke, and 1% due to myocardial infarction. The length of stay in the past year has decreased to less than 7 days. CONCLUSIONS: The current risk for ascending aortic aneurysm repair is low (< 2%) whether or not the aortic root or valve also needs repair, regardless of the cause of the aneurysm.
Intractable pain in children with terminal cancer.
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Determinants of early mortality and late survival in mitral valve endocarditis.
BACKGROUND: Infective mitral valve endocarditis continues to be a significant surgical challenge. The objective of this study was to examine our experience with mitral valve endocarditis surgery and identify determinants of early mortality and late survival. METHODS AND RESULTS: Over a 24-year period, mitral valve surgery was performed in 96 patients for infective mitral valve endocarditis. Patient age ranged from 20 to 78 years (median age, 52 years). There were 44 women (46%), and 48 of the 96 patients (50%) were in New York Heart Association functional class IV before surgery. Native valve endocarditis (NVE) and prosthetic valve endocarditis (PVE) were present in 72 patients (75%) and 24 patients (25%), respectively. Surgery during the active phase of endocarditis (AE) was required in 60 patients (62%) and during the healed phase (HE) in 36 (38%). The main indications for surgery in the AE group were congestive heart failure (60%), active sepsis (67%), peripheral emboli (47%), and acute renal failure (20%), and for the HE group the main indication was progressive congestive heart failure (69%). The overall operative mortality was 5.2%. Multivariate logistic regression analysis identified PVE (odds ratio [OR] 22.5; +/- 95% confidence interval, CI, 1.9 to 268; P = .014) and an associated procedure (OR 13.3; +/- 95% CI, 1.5 to 120; P = .021) to be independent predictors for early mortality. Follow-up was 97% complete, with a median of 3.5 years. Overall 5- and 10-year survivals were 83 +/- 4% and 63 +/- 8%, respectively. Multivariate analysis for late mortality identified PVE to be a significant predictor of late mortality (hazards ratio = 3.1, +/- 95% CI, 1.4 to 6.8, P = .006). There were no significant differences in long-term morbidity results among the various subsets of mitral valve endocarditis. CONCLUSIONS: Mitral valve surgery for infective endocarditis is a significant high-risk procedure for PVE and when combined with associated procedures. The activity of endocarditis does not appear to have any influence on early mortality or long-term survival.
Open-loop and closed-loop postural control mechanisms in Parkinson's disease: increased mediolateral activity during quiet standing.
Stabilogram-diffusion analysis was used to gain insights into how idiopathic Parkinson's disease (IPD) affects the postural control mechanisms involved in maintaining erect stance. Twenty-two subjects with IPD and twenty-four healthy elderly subjects were studied under eyes-open, quiet-standing conditions. The postural control mechanisms in the parkinsonian subjects, compared to the healthy elderly, were characterized by an increase in the effective stochastic activity in the mediolateral direction. Mediolateral posturographic measures were also associated with a history of falls and poor performance on clinical measures of balance. It is hypothesized that the increase in mediolateral activity in subjects with IPD may reflect an attempt to maintain potentially stabilizing movements during quiet standing in the face of impaired movement in the anteroposterior direction. This study supports the notion that mediolateral instability is an important posturographic marker of functional balance impairment in the elderly.
Stochastic resonance without tuning.
Stochastic resonance (SR) is a phenomenon wherein the response of a nonlinear system to a weak periodic input signal is optimized by the presence of a particular, non-zero level of noise. SR has been proposed as a means for improving signal detection in a wide variety of systems, including superconducting quantum interference devices, and may be used in some natural systems such as sensory neurons. But for SR to be effective in a single-unit system (such as a sensory neuron or a single ion channel), the optimal intensity of the noise must be adjusted as the nature of the signal to be detected changes. This has been thought to impose a limitation on the practical and natural uses of SR. Here we show that the ability of a summing network of excitable units to detect a range of weak (sub-threshold) signals (either periodic or aperiodic) can be optimized by a fixed level of noise, irrespective of the nature of the input signal. We also show that this noise does not significantly degrade the ability of the network to detect suprathreshold signals. Thus, large nonlinear networks do not suffer from the limitations of SR in single units, and might be able to use a single noise level, such as that provided by the intrinsic noise of the individual components, to enhance the system's sensitivity to weak inputs. This suggests a functional role for neuronal noise in sensory systems.
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Caenorhabditis elegans contains genes encoding two new members of the Zn-containing alcohol dehydrogenase family.
We have characterized two cDNA clones from the nematode Caenorhabditis elegans that display similarity to the alcohol dehydrogenase (ADH) gene family. The nucleotide sequences of these cDNAs predict that they encode Zn-containing long-chain ADH enzymes. Phylogenetic analysis suggests that one is most similar to dimeric class III ADHs found in diverse taxa; the other is most similar to the tetrameric forms of ADH previously described only in fungi.