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Biomedical subjects

W D Johnson

Publications and source records attributed to W D Johnson.

At least 163 records · Page 9Linked to original sources
PubMed1984

Angina pectoris and coronary bypass surgery: patterns of prevalence and recurrence in 3105 consecutive patients followed up to 11 years.

Many studies document the effectiveness of bypass surgery in relieving angina pectoris. Few, however, have described patterns of prevalence preoperatively and recurrence postoperatively. After excluding those known to be dead and those residing outside the continental United States, we attempted to contact all patients who had undergone first bypass surgery by us. Follow-up was 94.4% complete. Women had a higher prevalence of preoperative angina and lesser relief after surgery (p less than 0.01). Because of this difference, only men presenting with angina preoperatively were analyzed in detail. In this subgroup, the cumulative percentage of patients with total relief of angina was 87% after the first year; thereafter, the percentage decreased 6%/year. The cumulative percentage of patients improved (those with no angina plus those with less angina than before surgery) was 97% after the first year; thereafter the percentage decreased 0.9%/year. Duration of angina preoperatively had no effect on recurrence unless preoperative duration was less than 6 months. Preoperative left ventricular function had little effect on relief of angina postoperatively. In a short follow-up, 1.5 to 2 years after the original study, we found that patients with postoperative angina had twice the mortality rate of those totally free of angina (p = 0.000004). Furthermore, those with angina at rest had twice the mortality rate of those who had angina but never at rest (p = 0.009).

Adult↗
PubMed1984

The incidence of myoglobinuria in patients with pneumatic trousers.

The possible association between the use of pneumatic trousers and myoglobinuria was investigated. One hundred and four victims of multiple trauma were entered into a study over a three-month period. Patients who suffered serious injuries to two or more organ systems qualified for entrance into the study. Patients who arrived at the emergency department with inflated pneumatic trousers served as the test population (n = 50), and patients who did not have pneumatic trousers served as the controls (n = 54). Urine specimens were obtained from all patients just before the completion of their treatment in the emergency department. No patients in the control group had myoglobinuria 0%), and only one patient in the test group had myoglobinuria 2%). The results were not statistically significant. Myoglobinuria is not an acute complication of the use of pneumatic trousers. The presence of pneumatic trousers on a multiple-trauma patient is not an indication for routine screening for myoglobinuria in the emergency department.

Adult↗
PubMed1984

Detection of abnormal cells in white cell differentials: comparison of the HEMATRAK automated system with manual methods.

Automated differential systems can rapidly count larger numbers of cells compared with the standard manual procedure. When a fixed number of abnormal cells are interspersed randomly with a large number of normal cells, it can be shown mathematically that counting more cells increases the chances of detecting at least one abnormal cell. To test this hypothesis in a clinical setting, the authors compared 200-cell and 400-cell automated differentials obtained via the HEMATRAK Model 360 system with results of 100-cell differentials performed either manually or automatically for a group of 141 blood smears. Manual 100-cell differentials also were performed in a reference laboratory for comparison. In close agreement with theoretical expectation, both 200-cell and 400-cell differentials detected significantly more abnormal cells than did either the manual or automated 100-cell differential. Results of the latter two were not significantly different. Eighty-seven per cent of the slides that, according to the 100-cell manual differential, were without abnormal cells were found to have such cells on the 400-cell automated differential. Atypical lymphocytes and nucleated red blood cells were the abnormal cells most frequently identified.

Automation↗
PubMed1984

Effective hypertension control in an indigent population.

The blood pressure of 60 indigent hypertensive patients who were being treated in the general medicine clinic of a large state-run hospital was found to be unacceptably high after an average follow-up period of 107.5 months. Intensive treatment through a subspecialty clinic resulted in significant decreases in both the mean systolic pressure (from 176.2 to 144.9 mm Hg) and diastolic pressure (from 101.6 to 88.0 mm Hg). Improved blood pressure levels continued for as long as the patients were seen in the subspecialty clinic, but improvement was not maintained at an average of 17.1 months after discharge to the medicine clinic. The mean systolic and diastolic pressures were significantly higher at this time (161.2 and 94.4 mm Hg respectively). We conclude that treatment in a large medicine clinic is inefficient for hypertensive patients and that a subspecialty clinic format is much more successful.

Adult↗
PubMed1984

Percutaneous transluminal coronary angioplasty in patients with prior coronary artery bypass grafting.

Percutaneous transluminal coronary angioplasty (PTCA) has been used to treat patients with prior coronary artery bypass grafting who have stenosis of a saphenous vein graft and/or a native artery. During 53 months, 61 patients underwent 105 angioplasty attempts. Eighty lesions (76%) were successfully dilated in 46 of 61 patients (75%). Success in a patient was determined by a greater than or equal to 20% decrease in the percent diameter stenoses coupled with an improved clinical response; 52 patients had one prior CABG and nine patients had two or more prior CABGs. Multivessel disease was present in 56 patients (92%). A vein graft stenosis was successfully dilated in 26 of 33 cases (79%)--19 of 25 (76%) at an anastomotic site and seven of eight (88%) in the graft body. An arterial stenosis was successfully dilated in 37 of 52 cases (71%)--18 of 22 (82%) in the left anterior descending, 13 of 22 (59%) in the circumflex, 21 of 26 (81%) in the right coronary, and two (100%) in the left main coronary artery. There is no statistically significant difference in the incidence of success in dilating a vein graft or native artery. Complications included: one emergency CABG (1.6%), three myocardial infarctions (4.9%), and two deaths (3.3%). There were 15 unsuccessful PTCAs: Ten patients had elective CABG, one had emergency CABG, two received medical treatment, and two died. Forty-six patients are being followed-up: Twenty-eight (61%) continue to do clinically well, seven (15%) had another PTCA and remain well, and 10 (16%) had elective CABG because of restenosis and/or disease progression. There was one late death and one late myocardial infarction. Thus, 35 patients (57%) had continued clinical success without the need for repeat CABG; 89% had no angina or improved angina, and 90% had improved exercise treadmill results. PTCA is technically feasible in selected patients with prior CABG and can achieve a clinical response with an acceptable complication rate when compared to repeat CABG.

Angina Pectoris↗
PubMed1983

[Complete revascularization surgery in patients with coronary disease with severely reduced left ventricular function. Discrepancies in the evaluation of results].

Clinical data, function and compliance of left ventricle as well as regional wall motion were analysed in 17 patients with preoperatively limited left-ventricular function and signs of myocardial ischaemia after complete revascularisation surgery. Recatheterisation after 5.2 months on average after surgery showed improvement by one NYHA class, an increase of mean left-ventricular enddiastolic pressure, which was interpreted as "improved status of ischaemia", a decrease of left-ventricular compliance by 30%, of enddiastolic volume by 14% and of endsystolic volume by 20% (P less than 0.05). Loss of function occurred in 3 out of 92 bypasses. Up to the time of reporting, 22.4 months postoperatively, all patients have survived in a relatively satisfactory clinical state. All parameters of left-ventricular function as well as regional wall motion showed a tendency for improvement after surgery in the majority of patients. However, pre- and postoperative mean values were not significantly different (P greater than 0.05). Thus, despite clearcut improvement of clinical state and "ischaemia index", improvement of left-ventricular function and regional wall motion are not consistently demonstrable. The reasons of this discrepancy cannot be ascertained by this investigation. The quality of the surgical intervention and the sensitivity of parameter assessment cannot be held responsible.

Blood Pressure↗
PubMed1983

Characteristics of the acquired immunodeficiency syndrome (AIDS) in Haiti.

To identify the characteristics of the acquired immunodeficiency syndrome (AIDS) as it occurs in Haiti, we studied 61 previously healthy Haitians who had diagnoses of either Kaposi's sarcoma (15), opportunistic infections (45), or both (1) established in Haiti between June 1979 and October 1982. The first cases of Kaposi's sarcoma and opportunistic infections in Haiti were recognized in 1978-1979, a period that coincides with the earliest reports of AIDS in the United States. We do not believe that AIDS existed in Haiti before this period. The types of opportunistic infections and the clinical course in Haitians with Kaposi's sarcoma and opportunistic infections were similar in most aspects to those in patients with AIDS in the United States. The median age of Haitians with Kaposi's sarcoma and opportunistic infections was 32 years, and 85 per cent were men. The interval between diagnosis and death was six months in 80 per cent of the patients. Diarrhea was the most common reason for seeking medical attention in patients with opportunistic infections. Lymphopenia and skin-test anergy were observed in 86 and 100 per cent of patients, respectively. Potential risk factors (bisexual activity or blood transfusions) were identified in 17 per cent of male and 22 per cent of female patients. Demographic information suggests that patients belonged to all socioeconomic strata of Haitian society.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Subchronic feeding study in beagle dogs of N-methylpyrrolidone.

The potential toxicity of N-methylpyrrolidone was evaluated following dietary administration for 13 weeks to male and female beagle dogs at dosage levels of 25, 79 and 250 mg per kg body weight per day. Body weight gain and food consumption, hematological and clinical chemical data, and ophthalmic, gross and histopathological examinations were used to study possible toxicological or pathological effects. No statistically significant treatment-related effects that were judged to be biologically meaningful were seen in any parameters of either male or female animals exposed to N-methylpyrrolidone at any dose level. However, a dose-dependent decrease in body weight and increase in platelet count that correlated with increased megakaryocytes was observed. Serum cholesterol in males decreased with increasing doses.

Animals↗
PubMed1983

Subchronic feeding study of grape colour extract in beagle dogs.

The effect of feeding Welch's Special Grape Color Powder Type BW-AT at dose levels of 7.5 and 15% w/w in the diet for 90 days was studied in beagle dogs. Body-weight gain of male and female dogs at the high dose level was significantly decreased compared with control dogs. No other treatment-related effects were seen in food consumption, haematology, clinical chemistry, ophthalmology or gross and histopathological findings.

Animals↗
PubMed1983

Skeletal stabilization with a multiplane external fixation device. Biomechanical evaluation and finite element model.

The general question of the influence of fracture stability on bone healing remains unanswered and has important bearing on fracture stabilization by external fixation. The stiffness of an external fixator is dependent on pin placement and frame orientation. These parameters are under the surgeon's control, within limits set by soft tissue injury and fixator design. Fixator configuration parameters include common fragment pin separation, common fragment pin angle, common fragment pin number, effective pin length, use of transfixing pins versus half-pins, and use of two versus three connecting rods. Each configuration parameter was varied independently under compressive, bending, and torsional load to determine the influence of that parameter on fracture stability under such loads. The interaction between these configuration parameters is complex. In general terms, fracture site stability may be increased by increasing common fragment pin separation, placing common fragment pins orthogonal to one another, increasing common fragment pin number, decreasing effective pin length, using transfixing rather than half-pins, and using as many connecting rods as possible. The difference between fracture site stability attainable with transfixing pins and with half-pins may be minimal if implementation of the other parameters combined with half-pins is optimized.

Biomechanical Phenomena↗
PubMed1983

Bending stiffness of unilateral and bilateral fixator frames.

The structural and geometric fixator properties that best neutralize the prevailing anteroposterior and transverse bending moments at a tibial fracture site were analyzed in anatomic specimens. Clinically and mechanically, anterior unilateral frames were most effective, particularly when applied with relatively stiff components with a maximal spread between the pins in each main bony fragment and with placement of the longitudinal rod close to the tibia.

Fracture Fixation↗
PubMed1982

Combined two-generation reproduction-teratogenesis study of zearalenone in the rat.

The toxicity of zearalenone was studied in two generations of Wistar rats over approximately 10 months. Zearalenone was administered in the diet; the dose levels used were 0, 0.1, 1.0 and 10.0 mg per kg body weight per day in all generations. Animals in the F0 generation were bred twice to produce F1A and F1B generations. The F1A generation was bred to produce the F2A generation. The only lesion found at necropsy that could be attributed to zearalenone administration was increased medullary trabeculation of the femur in animals given the high dose. A dose-related increase in absolute and relative thyroid, pituitary and adrenal gland weights occurred in male and female rats of both the F1 and F1A generation. The alteration in the weights of these endocrine organs is probably a result of the estrogenic activity of zearalenone. Feeding of zearalenone caused decreases in fertility, number of viable offspring per litter and numbers of corpora lutea, implantations and resorptions per dam. Statistically significant differences were noted in the incidences of a number of skeletal and soft tissue abnormalities in both the F1B and F2A1 fetuses, especially at doses of 1.0 and 10.0 mg kg-1. These lesions most likely indicate a delay in fetal development. Unequivocal teratogenic effects could not be defined.

Abnormalities, Drug-Induced↗
PubMed1982

Coronary artery surgery in diabetics: 261 consecutive patients followed four to seven years.

Diabetes mellitus is a well established risk factor for coronary artery disease, but its effect on the conduct and results of bypass surgery (CABG) are not well documented. We identified 261 (11.9%) diabetics among 2192 patients operated August, 1972, through December, 1977. All patients were surveyed, in identical manner, during January, 1981. There were 51 (19.5%) dead, seven (3.3%) lost, and seven (3.3%) residing in foreign countries whom we did not attempt to follow. We divided the 261 patients into three groups by severity of diabetes: drug therapy 106 (40.6%), diet therapy 60 (23.0%), and borderline 95 (36.4%). Severity of diabetes had no effect on any of the factors we investigated. Compared with nondiabetics, diabetics had the same average age, a higher proportion of women, the same number of grafts per patient, slightly more bad ventricles, and a higher surgical and late mortality. Frequency of preoperative angina was slightly higher in diabetics. Relief of angina was essentially the same in both groups. There were 54 serious complications which occurred in 45 (17.2%) patients; of these, 20 (7.7%) were hospital mortalities. The only factors reaching statistical significance were the proportion of women and the surgical mortality in good ventricles. We conclude that the presence of diabetes does increase the morbidity and mortality associated with bypass surgery, but only to a relatively small degree and that controlled diabetes is not sufficient reason to avoid bypass surgery.

Coronary Artery Bypass↗
PubMed1982

Atherosclerosis and polyps of the colon. Quantification of precursors of coronary heart disease and colon cancer.

The prevalence of adenomatous and hyperplastic polyps of the colon and the degree of involvement of the aorta by atherosclerotic lesions were evaluated in 842 autopsies from New Orleans. A positive statistical association between the two variables was found in white males under 75 years of age. In black males a positive correlation between atherosclerotic lesions and adenomatous (but not hyperplastic) polyps was found. The most extensive involvement of the aorta by atherosclerosis was found in patients in whom adenomatous and hyperplastic polyps coincided. The possibilities that dietary factors may account for these findings and its relevance in relation to colon cancer and coronary heart disease are discussed.

Adult↗
PubMed1982

Incidental prostatic carcinoma: tumor extent versus histologic grade.

One hundred forty-three incidental carcinomas from 500 step-sectioned prostates were classified independently by two pathologists according to the Gleason system. The area involved by each tumor was measured by photographic techniques. Observer agreement was 94 per cent when tumors were divided into groups with "pattern scores" 4 or less (less than or equal to 4) and greater than 4 (greater than 4). About 25 per cent of tumors in both races had pattern scores 4 or less (less than or equal to 4). Tumors with pattern scores greater than 4 (greater than 4) were, on the average, significantly larger than those with pattern scores 4 or less (less than or equal to 4) (p less than 0.001). We therefore believe that the Gleason histologic classification system is reproducible and that it discriminates tumors with different biological behavior.

Adult↗