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Biomedical subjects

J J Collins

Publications and source records attributed to J J Collins.

At least 145 records · Page 8Linked to original sources
PubMed1992

Long-term follow-up of patients undergoing myotomy/myectomy for obstructive hypertrophic cardiomyopathy.

The long-term results of patients undergoing myotomy/myectomy of the ventricular septum for obstructive hypertrophic cardiomyopathy are documented in 31 patients (15 women, 16 men, age range 21 to 80 years [mean 55]) with mean New York Heart Association functional class III to IV congestive heart failure, who underwent radical myotomy/myectomy at the Brigham and Women's Hospital from 1972 to 1991. Preoperative gradients by catheterization or echocardiography ranged from 26 to 240 mm Hg (average 96). There were no operative deaths. Two patients developed early postoperative complete heart block requiring a transvenous pacemaker. Clinical follow-up was 1 to 14 years (mean 6.5). All surviving patients were restudied by echocardiography and clinical examination. The mean postoperative functional class was II. Postoperative gradients ranged from 0 to 30 mm Hg (mean 4.5) (p less than 0.001 compared with preoperative values). There were 5 late deaths (low cardiac output in 2, stroke in 2, and acute respiratory failure in 1); 4 of 5 deaths occurred in patients with concomitant coronary artery disease. Survival at 10 years was 86 +/- 9%. There were no reoperations for subaortic obstruction.

Cardiomyopathy, Hypertrophic↗
PubMed1992

Comparison of cefuroxime axetil and doxycycline in the treatment of early Lyme disease.

OBJECTIVE: To compare the efficacy of cefuroxime axetil and doxycycline in the treatment of patients with Lyme disease associated with erythema migrans. DESIGN: Randomized, multicenter, investigator-blinded clinical trial with clinical evaluations during treatment (8 to 12 days) and at 1 to 5 days and 1, 3, 6, 9, and 12 months post-treatment. SETTING: Three university referral centers and one private practice. PATIENTS: A total of 123 patients with physician-documented erythema migrans. INTERVENTION: Patients were treated orally for 20 days with either cefuroxime axetil, 500 mg twice daily (63 patients), or doxycycline, 100 mg three times daily (60 patients). MEASUREMENTS: Resolution of erythema migrans and of signs and symptoms related to early Lyme disease as well as prevention of late Lyme disease. RESULTS: A satisfactory clinical outcome (success or improvement) was achieved in 51 of 55 (93%) evaluable patients treated with cefuroxime axetil and in 45 of 51 (88%) patients treated with doxycycline (difference, 5%, 95% Cl, -5% to 14%). The only complication at 1 month post-treatment was Lyme arthritis in one patient who received doxycycline. Of the patients with satisfactory outcomes at 1 month post-treatment who were evaluable at 1 year post-treatment, a satisfactory outcome was achieved in 43 of 48 (90%) and in 35 of 38 (92%) patients treated with cefuroxime axetil and doxycycline, respectively (difference, -2%; Cl, -12% to 7%). Lyme arthritis did not develop in any patient after 1 month post-treatment, whereas peripheral neuropathy was suspected in one patient treated with cefuroxime axetil. Thirty percent of patients treated with cefuroxime axetil and 32% of those treated with doxycycline had one or more drug-related adverse events. Doxycycline was associated with more photo-sensitivity reactions (15% compared with 0%; P = 0.001) and cefuroxime axetil with more diarrhea (21% compared with 7%; P = 0.035) and Jarisch-Herxheimer reactions (29% compared with 8%; P = 0.005). CONCLUSIONS: Cefuroxime axetil is well tolerated and appears to be equally as effective as doxycycline in the treating of early Lyme disease and in preventing the subsequent development of late Lyme disease.

Adolescent↗
PubMed1992

Symmetry-breaking bifurcation: a possible mechanism for 2:1 frequency-locking in animal locomotion.

The generation and control of animal locomotion is believed to involve central pattern generators - networks of neurons which are capable of producing oscillatory behavior. In the present work, the quadrupedal locomotor central pattern generator is modelled as four distinct but symmetrically coupled non-linear oscillators. We show that the typical patterns for two such networks of oscillators include 2:1 frequency-locked oscillations. These patterns, which arise through symmetry-breaking Hopf bifurcation, correspond in part to observed patterns of 2:1 frequency-locking of limb movements during electrically elicited locomotion of decerebrate and spinal quadrupeds. We briefly describe how our theoretical predictions could be tested experimentally.

Animals↗
PubMed1992

Clinical comparison of cefuroxime axetil and amoxicillin/clavulanate in the treatment of patients with acute bacterial maxillary sinusitis.

PURPOSE: This multicenter study compared the clinical and bacteriologic efficacy of two oral antibiotics, cefuroxime axetil and amoxicillin/clavulanate, in the treatment of acute bacterial maxillary sinusitis. PATIENTS AND METHODS: Three hundred seventeen patients with clinical and radiographic evidence of acute maxillary sinusitis were enrolled at nine centers and were randomly assigned to receive 10 days of treatment with cefuroxime axetil 250 mg twice daily (n = 157) or amoxicillin/clavulanate 500 mg three times daily (n = 160). Patients were assessed for both clinical and bacteriologic responses once during treatment (5 to 7 days) and twice after treatment (1 to 3 days and 4 weeks). Bacteriologic assessments were based on needle aspirates of the maxillary sinus obtained pretreatment and, when possible, at the first posttreatment visit. RESULTS: Organisms were isolated from the pretreatment sinus aspirates of 198 of 317 (62%) patients, with the primary isolates being Streptococcus pneumoniae (22%), Haemophilus spp. (17%), Staphylococcus aureus (13%), and Haemophilus influenzae (10%). A satisfactory clinical outcome (cure or improvement) was achieved in 85% (98 of 115) and 82% (102 of 124) of the clinically evaluable patients treated with cefuroxime axetil or amoxicillin/clavulanate, respectively (P = 0.446). With respect to the eradication of the bacterial pathogens, a satisfactory outcome (cure or presumed cure) was obtained in 84% (31 of 37) and 87% (34 of 39) of bacteriologically evaluable patients treated with cefuroxime axetil or amoxicillin/clavulanate, respectively (p = 0.567). Treatment with amoxicillin/clavulanate was associated with a significantly higher incidence of drug-related adverse events (13% versus 3%, p = 0.001), particularly diarrhea (8% versus 1%, p = 0.001). Two patients in the cefuroxime axetil group and three patients in the amoxicillin/clavulanate group withdrew from the study due to adverse events. CONCLUSIONS: Our results indicate that cefuroxime axetil twice a day is as effective as amoxicillin/clavulanate three times a day in the treatment of acute bacterial maxillary sinusitis but produces fewer adverse effects.

Acute Disease↗
PubMed1992

Combined carotid and coronary revascularization: the preferred approach to the severe vasculopath.

The timing of carotid endarterectomy (CEA) and coronary revascularization (CABG) for concomitant disease is controversial. Results of combined CEA/CABG in 127 patients (age range, 46 to 82 years; mean age, 65 years; 61% male) from 1978 to 1991 were reviewed. Ninety-five patients (75%) were in New York Heart Association functional class III or IV, 48 (38%) had left main coronary artery disease, and 32 (28%) had depressed ejection fraction ( < 0.50). Forty (32%) had asymptomatic bruits, 61 (48%) transient ischemic attacks, and 26 (20%) prior strokes. Seventy-five (59%) had bilateral carotid stenosis, including 20 (16%) with contralateral occlusions. Perioperative mortality was 7 of 127 (5.5%), and all deaths were cardiac related. Myocardial infarctions occurred in 6 of 127 patients (4.7%) and were nonfatal in 3 (2.3%). Permanent strokes occurred in 7 of 127 (5.5%) and were ipsilateral in 5 (3.9%). Perioperative stroke did not occur in the asymptomatic group, but the risk was higher in those with prior stroke (19%) or with contralateral carotid occlusion (15%). The stroke risk for our patients with carotid disease having CABG without CEA is not known, but the literature reports rates as high as 14%. For our patients without known concomitant disease, the risk of permanent stroke was 1.0% (31/3012) for isolated CABG and 1.5% (7/482) for isolated CEA. The late results after CEA/CABG revealed a 5-year survival of 70% +/- 5%, which correlated with ejection fraction ( > or = 0.50, 81% +/- 5%; < 0.50, 45% +/- 11%; p < 0.003). Freedom from late permanent ipsilateral stroke was 97% +/- 2% at 8 years. Freedom from stroke at 5 years was lower among patients with a previous stroke (71% +/- 10%) compared with transiently symptomatic (90% +/- 4%) and asymptomatic (96% +/- 4%) patients (p < 0.03). Combined CEA/CABG is a useful option in this high-risk group of patients with extensive atherosclerosis; avoids a subsequent hospitalization, anesthetic, and delay period; and provides long-term protection from ipsilateral stroke.

Actuarial Analysis↗
PubMed1992

Subchronic toxicity studies of t-butyl alcohol in rats and mice.

The purpose of this study was to evaluate the toxicity of t-butyl alcohol, an important commodity chemical, an additive to unleaded gasoline, and a contaminant of drinking water. Ninety-day toxicity studies were conducted in B6C3F1 mice and Fischer 344 (F344) rats of both sexes using dosed water. Dose levels of t-butyl alcohol were 0, 0.25, 0.5, 1, 2, and 4% (w/v). Lethality was observed at the 4% level of both sexes and species. Weight-gain depression was present in all dose levels of male rats; 4% female rats; 1, 2, and 4% male mice; and 2 and 4% female mice. Water consumption was increased at lower dose levels in male rats and decreased in the higher dose levels of both sexes of rats and female mice. Clinical signs in rats were ataxia in both sexes and hypoactivity in males. Clinical signs in mice were ataxia, abnormal posture, and hypoactivity. In rats, urine volumes were reduced, in association with crystalluria. Gross lesions at necropsy were urinary tract calculi, renal pelvic and ureteral dilatation, and thickening of the urinary bladder mucosa. Microscopic lesions were hyperplasia of transitional epithelia and inflammation of the urinary bladder. In male rats treated with t-butyl alcohol, microscopic renal changes were suggestive of alpha-2 mu-globulin nephropathy. No-effect levels for the urinary tract lesions were 1% in male rats and mice (803.7 mg/kg/day for the male rats and 1565.8 mg/kg/day for the male mice) and 2% in female rats and mice (1451.5 mg/kg/day for the female rats and 4362.9 mg/kg/day for the female mice). The results indicate that in rodents the urinary tract is the target organ for t-butyl alcohol toxicity, and males are more sensitive to t-butyl alcohol toxicity than females.

Animals↗
PubMed1992

Phase I study of subcutaneously-administered bacterially-synthesised recombinant human granulocyte-macrophage colony-stimulating factor.

A phase I study was initiated to test the effect of bacterially-synthesised recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF). 15 patients with advanced cancers were entered into the study and 14 were evaluable. Patients were administered a single subcutaneous injection (3.0-300 micrograms/m2) of rhGM-CSF. Starting at a concentration of 100 micrograms/m2, an approximate 2-fold increase in leucocyte count was noted 24 h after the injection. By 48 h the counts had returned to baseline. The 300 micrograms/m2 concentration also induced an approximate 2-fold increase. The leucocytosis was associated with a predominant increase in circulating neutrophils and bands. An increase in monocytes was also noted, but peak levels were recorded 48-72 h after the injection. At both the 100 micrograms/m2 and the 300 micrograms/m2 doses, significant levels of circulating rhGM-CSF were detected. The levels measured in the plasma of patients receiving 300 micrograms/m2 were over 10-fold greater than those measured at 100 micrograms/m2. There was no detectable antibody formation against the rhGM-CSF in any of the study patients. The drug was exceptionally well-tolerated. This study shows that rhGM-CSF can be safely administered by subcutaneous administration and a single injection is capable of inducing a leucocytosis with increased circulating neutrophils, bands, and monocytes when doses are used which result in significant levels of circulating rhGM-CSF.

Dose-Response Relationship, Drug↗
PubMed1992

Red cell transfusions in coronary artery bypass surgery (DRGs 106 and 107)

To study red cell transfusion practice in 3216 coronary artery bypass graft (CABG) cases in 11 hospitals in 1988, abstracted patient records were stratified by diagnosis related group (DRG) (that is, DRG 106, coronary artery bypass without catheterization, or DRG 107, coronary artery bypass with catheterization) and International Classification of Diseases, 9th revision, Clinical Modification (ICD-9-CM) surgical procedure code. Means of units per transfused patient, age and length of stay, and in-hospital mortality rates were significantly greater for patients in DRG 106 than DRG 107. Gender was a significant factor for transfusion outcomes; female patients were more likely to undergo transfusion, and, when transfused, they received more units of red cells than male patients. For a given DRG/ICD-9-CM surgical procedure class, significant differences were found between hospitals in the percentage of patients transfused, but not in mean units of red cells per transfused patient. However, within individual hospitals, the proportion of patients transfused and the number of units per transfused patient did not vary significantly across DRG/ICD-9-CM procedure classes. These results suggest that circumstances operating within a hospital, still to be identified, had more influence on transfusion decisions than the nature of the surgical intervention.

Aged↗
PubMed1992

Ultrasound scattering from spherical tumours.

The interaction of biomedical ultrasound with spherical tumours in the human body is investigated using analytic methods which predict the angular distribution of the ultrasound scattered by the tumour. Both the tumour and the surrounding tissue are considered to be lossy elastic media, which support shear-wave modes in addition to the familiar compressional-wave acoustic modes. Exact expressions for the angular distribution of the ultrasonic energy scattered by the tumour are used to illustrate graphically the behaviour of plane ultrasound wave interactions.

Humans↗
PubMed1992

Improved surgical approach to left atrial appendage aneurysm.

Left atrial appendage aneurysm is a rare anomaly, which usually presents with arrhythmia or cerebral embolism. Diagnostic evaluation traditionally required cardiac catheterization, and surgical resection required cardiopulmonary bypass. Utilizing intraoperative transesophageal echocardiography and surgical stapling devices, we have streamlined our operative technique, allowing resection of a left atrial appendage aneurysm without cardiopulmonary bypass. This report of two cases treated over the past decade demonstrates the evolution of our surgical technique.

Adult↗
PubMed1992

Acute bacterial endocarditis. Optimizing surgical results.

BACKGROUND: Acute bacterial endocarditis continues to be a condition with high morbidity. Although the majority of patients are treated by high-dose antibiotics, a high-risk patient group requires surgical intervention, which is the subject of this article. METHODS AND RESULTS: From 1972 to 1991, 3,820 patients underwent heart valve replacement at the Brigham and Women's Hospital, Boston. Of this group, 158 patients underwent surgery for acute bacterial endocarditis: 109 had native valve endocarditis (NVE), and 49 had prosthetic valve endocarditis (PVE). There were 108 men and 50 women with a mean age of 49 years (range, 16-79 years); 64% were New York Heart Association functional class IV before surgery, and 12% of the group had a history of intravenous drug abuse. In both NVE and PVE groups, Streptococcus was the predominant infecting agent. Uncontrolled sepsis, progressive congestive failure, peripheral emboli, and echocardiographically demonstrated vegetations were the most common indications for surgery. Eighty-five percent of patients had a single-valve procedure, 15% had a multivalve procedure, and 34 patients had other associated major cardiac procedures. The operative mortality was 6% in NVE and 22% in PVE. Long-term survival at 10 years was 66% for NVE and 29% for PVE. Freedom from recurrent endocarditis at 10 years was 85% for NVE and 82% for PVE. The main factors associated with decreased survival overall were PVE and nonstreptococcal infection. CONCLUSIONS: The morbidity and mortality after surgical treatment of acute endocarditis depend on the site, the severity, and the subject infected. Early aggressive surgical intervention is indicated to optimize surgical results, especially in patients with nonstreptococcal infection or PVE.

Aortic Valve↗
PubMed1992

Experimental graft arteriosclerosis. I. The Lewis-to-F-344 allograft model.

Progressive graft arteriosclerosis is responsible for the majority of late deaths occurring in cardiac transplant recipients. In order to define a model of this disease in the rat, we exchanged heterotopic cardiac allografts between MHC-compatible inbred strains. Lewis rats served as donors and F-344 rats as recipients. Twenty allografts were followed by daily palpation and removed at the time of terminal rejection or on the 120th postoperative day for pathologic study. Sixteen allografts (80%) survived at least three weeks, and five allografts (25%) survived indefinitely. The majority of arteries (greater than 90%) examined demonstrated significant intimal disease; histologic findings in lesions in allografts rejecting at early time points included intense mononuclear cell infiltration of the intima, while lesions in long-term-surviving allografts demonstrated fibrous intimal thickening, which is characteristic of graft arteriosclerosis seen clinically. A limited course of cyclosporine therapy in F-344 recipients increased the incidence of indefinite allograft survival from 25% to 86%, and was associated with a modest reduction in the amount of intimal disease observed. These results suggest that this model should be useful in future studies regarding the pathogenesis and therapy of cardiac graft arteriosclerosis.

Animals↗
PubMed1991

Doppler echocardiographic comparison of the Carpentier and Duran anuloplasty rings versus no ring after mitral valve repair for mitral regurgitation.

To compare the hemodynamic results of different anuloplasty techniques of primary valve repair for mitral regurgitation, 122 patients were prospectively studied with Doppler echocardiograms 5 to 10 days after operation. Seventy-seven patients had mitral valve prolapse, 27 had coronary artery disease, 13 patients had rheumatic mitral valve lesions and 5 patients had infective endocarditis. Forty-eight patients received the flexible Duran ring, 46 received the more rigid Carpentier ring and 28 patients received no ring. Doppler echocardiography demonstrated a significant decrease in mitral valve area estimated by the pressure half-time method in patients who received either a Carpentier (2.6 +/- 0.8 cm2) or Duran ring (2.8 +/- 0.8 cm2) when compared with patients who received no ring (3.2 +/- 0.7 cm2) (p = 0.01). No significant differences were observed for peak transmitral diastolic velocity, peak transmitral diastolic gradient, or the grade of mitral regurgitation by color flow Doppler mapping between patients with and without rings. The etiology of mitral disease and concomitant surgical procedures accompanying mitral valve repair did not significantly influence mitral valve area, peak velocity or peak gradient. These data suggest that Carpentier and Duran rings decrease the hemodynamic mitral valve area; however, the decrease in valve area is small and not associated with a clinically important increase in transvalvular gradient.

Echocardiography, Doppler↗
PubMed1991

Freshwater molluscs as indicators of bioavailability and toxicity of metals in surface-water systems.

Freshwater molluscs--snails and bivalves--have been used frequently as bioindicator organisms. With increasing needs for research on contaminant effects in freshwater ecosystems, this kind of biomonitoring is likely to develop further in the future. Molluscs can be used effectively for studies of both organic and inorganic contaminants; this review focuses on studies involving bioaccumulation and toxicity of metals. Two important advantages of snails and bivalves over most other freshwater organisms for biomonitoring research are their large size and limited mobility. In addition, they are abundant in many types of freshwater environments and are relatively easy to collect and identify. At metal concentrations that are within ranges common to natural waters, they are generally effective bioaccumulators of metals. Biomonitoring studies with freshwater molluscs have covered a wide diversity of species, metals, and environments. The principal generalization that can be drawn from this research is that bioaccumulation and toxicity are extremely situation dependent; hence, it is difficult to extrapolate results from any particular study to other situations where the biological species or environmental conditions are different. Even within one species, individual characteristics such as size, life stage, sex, and genotype can have significant effects on responses to contaminants. The bioavailability of the metal is highly variable and depends on pH, presence of organic ligands, water hardness, and numerous other controlling factors. Despite this variability, past studies provide some general principles that can facilitate planning of research with freshwater snails and bivalves as metal bioindicators. These principles may also be useful in understanding and managing freshwater ecosystems. Bioaccumulation of metals in biota is a function of both uptake and depuration. Uptake in molluscs may be through either of two vectors--ingestion of food and other metal-containing substances or through direct adsorption of dissolved constituents. Under some conditions, the bioconcentration factors can be in the range of 10(3) to 10(6), relative to water. Most studies that provide comparisons among taxonomic groups indicate that bioaccumulation in molluscs is greater than that is fish. However, such comparisons should be interpreted with caution because metals tend to be nonuniformly distributed among different organs in both molluscs and fish. Bioaccumulation and acute and chronic toxicity are highly dependent on metal speciation. Mainly because of this influence of metal speciation, toxicity and bioaccumulation do not have a consistent relation to each other. Sensitivity to toxic effects of a metal is likely to be considerably greater in juvenile or larval stages than in adults.

Animals↗
PubMed1991

Coronary bypass grafting with totally calcified or acutely dissected ascending aorta.

From August 1984 through November 1988, 10 of 2,658 patients undergoing coronary artery bypass grafting had ascending aortic disease that was not amenable to proximal anastomoses for coronary bypass grafting. This was due to a calcified aorta in 6 and acute aortic dissection in 4. There were 5 male and 5 female patients with a mean age of 71 years. Cannulation site was the femoral artery in 5, ascending aorta in 3, and aortic arch in 2. Profound hypothermia and ventricular fibrillation, with no cross-clamp or cardioplegia, was used in 9 patients, and circulatory arrest in 1. In 8 patients a single internal mammary artery was used as the total inflow with a saphenous vein graft brought off the internal mammary artery to one or more distal left-sided coronary vessels. Bilateral internal mammary arteries were used in 2 other patients. Operative mortality was zero. There was one perioperative myocardial infarction and one transient stroke without sequelae. All patients have done well from 1 to 6 years postoperatively. These data support the use of internal mammary arteries as single or bilateral proximal conduits for other venoarterial bypass grafts when the aorta is extensively diseased either by calcification or dissection.

Aged↗