Biomedical subjects
Publications and source records attributed to B Weiner.
We report an unusual complication of oral-gastric lavage in a drug overdose patient. During the lavage procedure, the oral-gastric tube became impacted in the esophagus. Forceful removal of the tube resulted in an esophageal tear. The patient did well with conservative management and was discharged with no long-term sequelae.
The effect of the postoperative administration of digoxin to patients undergoing coronary artery bypass surgery on the incidence of supraventricular arrhythmias was studied. Patients were randomly assigned to a control group (n = 51) or digoxin group (n = 47) on a prospective basis. Patient characteristics were similar in both groups, and no patients were receiving digoxin therapy preoperatively or other antiarrhythmic medications. All patients had normal systolic ejection fractions, renal function, and hepatic function. Eight patients (16%) in the control group developed postoperative arrhythmias while seven patients (15%) in the digoxin group developed supraventricular arrhythmias. This difference was not significant. Two patients in the digoxin group developed digoxin-induced arrhythmias, and two other patients experienced digoxin-related nausea and vomiting, which were resolved with discontinuation of the drug. The postoperative administration of digoxin to patients undergoing coronary artery bypass surgery had no effect on the incidence of supraventricular arrhythmias. The prophylactic use of digoxin therapy in this patient population is not recommended unless there is a history of arrhythmias responsive to digoxin therapy.
Vegetarians have an apparent diminished risk for the development of ischemic coronary heart disease. This may be secondary to dietary effects of plasma lipids and lipoproteins, but platelets, which may also play a role, have also been observed to have aberrant functions in vegetarians. We measured plasma lipid and lipoprotein levels, platelet function, platelet fatty acid levels, and platelet active prostaglandins in ten strict vegetarians (vegans), 15 lactovegetarians, and 25 age- and sex-matched omnivorous controls. The most striking observations were a highly significant rise in platelet linoleic acid concentration and a decline in platelet arachidonic acid concentration in both vegetarian subgroups as compared with omnivorous controls. Serum thromboxane and prostacyclin levels as well as results of platelet aggregation studies did not differ among the groups tested. Cholesterol levels were significantly lower in both vegetarian groups as compared with controls, but plasma high- and low-density lipoprotein levels were lower only in the vegan subgroup as compared with omnivores. If diet produces these changes in platelet fatty acid and plasma lipid levels it may contribute to the decreased risk of coronary heart disease and possibly atherosclerosis in vegetarians.
The use of the calcium channel-blocking agent, verapamil, in beta-blocked patients has been the subject of intense investigation, particularly because both verapamil and the beta-blockers can produce negative inotropic effects. We studied the hemodynamic effects of verapamil in beta-blocked dogs to establish specific measurements that could be used clinically for early identification of combined negative inotropism. Seven anesthetized, mongrel dogs were beta-blocked with propranolol, and then given 2.5-, 5.0-, and 10.0-mg iv boluses of verapamil. The 2.5- and 5.0-mg boluses represent clinical doses, whereas the 10.0-mg bolus is a large pharmacologic dose. Hemodynamic measurements showed that verapamil was well tolerated at clinical doses; increases in stroke volume compensated for decreases in mean arterial pressure. At high doses of verapamil this response was not observed and left ventricular stroke work decreased. Cardiac and stroke indices were not useful indicators of combined drug toxicity in this dog model.
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A prospective, double-blind trial of a single preoperative dose of ceftriaxone, a new long-acting cephalosporin, versus one preoperative and three postoperative doses of cefazolin was carried out in 81 patients at high risk of infection after biliary surgery. Indications for antibiotic prophylaxis included recent or ongoing cholecystitis (52 patients), common duct stones (14 patients), common duct obstruction (3 patients), and age greater than 70 years (22 patients). Intraoperative bile cultures were positive in 7 of 41 patients (17.1 percent) given ceftriaxone and 12 of 40 patients (30 percent) given cefazolin, but there were no wound infections in either group. Neither regimen was associated with significant antibiotic resistance. Side effects, such as proteinuria and elevated liver transaminases and alkaline phosphatase levels, were transient and not definitely related to the antibiotics. We conclude that a single preoperative dose of ceftriaxone is as effective as multiple perioperative doses of cefazolin in the prophylaxis of infection associated with biliary tract surgery.
Warfarin currently is the most widely used agent in the prevention of thrombosis and embolism after prosthetic cardiac valve replacement. Since smoking has been shown to increase the requirement for medications undergoing hepatic metabolism, this study was designed to determine if a correlation exists between smoking history and warfarin daily maintenance dose (DMD) in patients undergoing cardiac valve replacement. Of 200 charts retrospectively reviewed at the New England Medical Center, 174 satisfied the criteria for inclusion in the study (normal hepatic, renal, and hematologic function, and absence of complicating medications). The study population included aortic, mitral, and combined valve replacement. Study groups consisted of 117 nonsmokers (Group A), 23 light smokers (Group B), and 34 heavy smokers (Group C). Thirty-three percent of patients required a low DMD of warfarin (less than or equal to 2.5 mg), 43 percent required a moderate DMD (greater than 2.5-7.5 mg), and 24 percent required a high DMD (greater than 7.5 mg). Each of the subgroups followed a similar pattern. In Group A, there were 31 percent low, 44 percent moderate, and 25 percent high-dose requiring patients. In Group B, there were 48 percent low, 39 percent moderate, and 13 percent high-dose requiring patients and in Group C there were 29.5 percent low, 41 percent moderate, and 29.5 percent high-dose requiring patients. Chi-square analysis did not demonstrate any statistically significant difference between smokers and nonsmokers in regard to daily maintenance warfarin dose (p = 0.5). The study population followed a normal pattern of distribution in regard to warfarin dosage. On the basis of these data we conclude that smoking history does not affect warfarin dose requirement.
This investigation attempted to replicate and to clarify methodologically an investigation by Pollak and Gilligan (1982). Those investigators reported sex differences in violence imagery to Thematic Apperception Test (TAT) pictures depicting affiliation and achievement situations. Pollak and Gilligan concluded that men perceive danger in situations of affiliation whereas women perceive danger in situations of achievement. It was demonstrated in the present study that Pollak and Gilligan incorrectly classified TAT cards into motivational categories, which may have resulted in incorrect inferences. In addition, their findings could not be replicated when using four different systems for classifying TAT cards into motivational categories. Other potential sources of error in their research, including a restrictive scoring scheme for hostility, unusual instructions, and failure to control for sex role in the TAT pictures, did not influence the pattern of results.
In 36 patients with normal renal function receiving hydrochlorothiazide and propranolol, lying diastolic blood pressure remained above 95 mmHg. In a double-blind trial, Step 3 therapy with 5-40 mg/day of minoxidil reduced blood pressure somewhat more effectively than 25-200 mg/day of hydralazine. The percentage of patients with lying diastolic blood pressure below 90 mmHg was 69 versus 35% at four weeks, and 55 versus 40% at 28 weeks. Transient falls in blood pressure within 4 h of any dose were greater with hydralazine which usually needed to be given in divided daily doses. Minoxidil caused tachycardia, and more adverse effects. Minoxidil is more effective, produces more consistent blood pressure control throughout the day, and may often be administered once daily.
Mitral valve prolapse (MVP) is a predisposing factor for cerebral ischemia, especially in young adults. Cerebral embolization of intracardiac thrombi is the probable mechanism in many cases. Platelets play a key role in the development of thrombi. We found that platelet factor 4, a marker protein of platelet activation, was elevated in 12 of 33 MVP patients (36%) without a history of stroke. This finding indicates that platelets are frequently activated in asymptomatic MVP patients and may allow identification of a subgroup of MVP patients with activated platelets who are at increased risk for emboli.
A training program was designed to teach mentally retarded adults working in sheltered workshops to attribute their success on various assembly tasks to high effort and ability and their failure to lack of effort. These subjects were judged as having motivational problems and also demonstrated decreased levels of performance on assembly tasks following failure experience. They received either individual attribution training, group filmstrip attribution training, or were placed in a control condition. Only the attribution-trained subjects subsequently exhibited more positive reactions to failure, increasing their performance speed in the face of failure. Both training conditions were effective, although filmstrip training was somewhat more beneficial than was individual training.
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In a previous study, we demonstrated that certain disposable coils are contaminated with zinc and release substantial quantities of zinc during hemodialysis, producing high postdialysis plasma zinc concentrations. The present investigation was undertaken to monitor plasma and dialysis fluid zinc and copper throughout dialysis and to estimate plasma zinc and copper uptake. Aluminum, cadmium, and lead release from coils was also determined. Venous plasma, arterial plasma, and coil chamber fluid were sampled periodically during dialysis; the trace metal concentrations were determined by flame atomic absorption spectrophotometry. Release of considerable quantities of zinc from the coils into the dialysis fluid, with uptake into the patient's plasma, was found. Approximately one-half of the plasma zinc uptake occurred within the first 45 min. Coils from different lots released significantly (p less than 0.001) different quantities of zinc. Plasma uptake of zinc ranged from 3.2 mg to 23.0 mg, with a mean (+/-SD) of 15.0 +/- 6.1 mg. Copper release and uptake was low. No detectable release of lead, cadmium, or aluminum was observed. The results suggest that zinc release from disposable dialysis coils should be assessed before recommending that hemodialysis patients receive zinc supplements.
A 3 1/4-year study assessed intervention approaches for hemodialysis-associated hepatitis. A 12-month retrospective study was followed by one year of prospective surveillance (during which attention to hygienic techniques was encouraged) and then by a 15-month period during which antigen-positive cases were transferred from study centers to an isolation hemodialysis center (IHL). The incidence of hepatitis B infection (HBI) fell 35.9% in study centers during surveillance; this was followed by a 50.0% drop during the IHC phase. The total 67.9% drop during the entire study period was statistically highly significant; the IHC contributed significantly more to the total drop than did surveillance alone. At comparison units, HBI increased 97.9% during the same period. This study indicates that HBI incidence can be markedly reduced by a combination of surveillance and assignment of antigen-positive patients to a separate dialysis unit.
It has been suggested that hemodialysis patients might benefit from zinc supplements. However, little attention is given to the trace element content of renal dialysis fluids or to contamination of such fluids with trace metals. Pre- and postdialysis plasma copper and zinc concentrations of patients at two hospital dialysis units were measured by atomic absorption spectrophotometry. The plasma zinc concentration increased substantially in 34 of 37 patients as a result of dialysis. Measurement of dialysate zinc concentrations after primary source of zinc. Because of the possibility of zinc toxicity, zinc nutritional status should be carefully evaluated before recommending zinc supplementation for dialysis patients. Uremic patients dialyzed with certain disposable Cuprophan-membrane coils receive substantial quantities of zinc during dialysis; other Cuprophan-membrane coils tested released negligible quantities of zinc.
Studies were performed on 12 patients with idiopathic hypercalciuria to evaluate the hypothesis that the acid load accompanying potassium acid phosphate would adversely affect renal calcium reabsorption and citrate excretion compared to the neutral form of the phosphate salt. During acute clearance studies, neutral phosphate (NP) led to a fall in FECa (2.2 +/- 0.6% to 0.8 +/- 0.1%, P less than 0.02) and no change in titratable acidity (TA) or net acid excretion (NAE). Acid phosphate (AP) did not reduce FECa acutely, and led to a rise in TA (22 +/- 4 to 62 +/- 6 muEq/min, P less than 0.02) and NAE (46 +/- 6 to 6 89 +/- 7 muEq/min, P less than 0.02). During chronic administration, AP resulted in higher urinary calcium excretion in both absorptive (187 +/- 29 vs. 141 +/- 18 mg/day, P less than 0.02) and renal hypercalciuric patients (233 +/- 24 vs. 173 +/- 190.02 mg/day, P less than 0.02). Also, TA and NAE were higher following AP, whereas citrate excretion was lower (375.4 +/- 64.6 vs. 633.4 +/- 28.8 mg/day, P less than 0.01). These data suggest that the reported ineffectiveness of AP in the therapy of nephrolithiasis may be related to the deleterious effects of the acid load on calcium and citrate metabolism.
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