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Biomedical subjects

C J Mullany

Publications and source records attributed to C J Mullany.

80 records · Page 5Linked to original sources

Measurement of plasma free fatty acid turnover and oxidation using [1-13C]palmitic acid.

The measurement of plasma free fatty acid turnover and oxidation by means of the isotopic dilution technique using a radiolabeled free fatty acid has proven useful for the in vivo study of fat metabolism in animals. However, because of the ethical considerations regarding the administration of radioisotopes to humans, there is a lack of adequate information regarding the in vivo regulation of free fatty turnover and oxidation in humans, particularly children. Consequently, we have developed a technique using the stable, nonradioactive [1-13C]palmitic acid molecule as free fatty acid tracer to measure plasma free fatty acid metabolism in vivo. We have analysed the isotopic enrichment of plasma palmitate by selected ion monitoring on a gas chromatograph mass spectrometer and we have used an isotope ratio mass spectrometer to determine the much lower isotopic enrichment of the expired CO2. We have found this technique to be safe to administer, to a high degree of analytical reproducibility, and to yield values in dogs comparable with those obtained using [1-14C]palmitic acid as the tracer.

Animals↗

Glucose requirements following burn injury. Parameters of optimal glucose infusion and possible hepatic and respiratory abnormalities following excessive glucose intake.

Glucose and leucine metabolism in 18 severely burned patients were studied using the primed constant infusion of U-13C-glucose and 1-13C-leucine, respectively. The leucine data were used to calculate rates of whole-body protein synthesis. In four additional burn patients and seven normal controls, the effects of exogenously infused insulin on the metabolism of infused glucose were evaluated. Also, the effect on leucine metabolism of adding insulin to infused glucose was tested and rates of protein synthesis were calculated. The protein studies were divided into two groups depending on the rate of glucose infusion. Protein synthesis was 4.3 + 0.54 g protein/kg/day during the lower infusion rates (1.4--4.5 mg/kg/min) and 5.17 + 0.19 g protein/kg/day during the higher infusion rates (4.7--9.3 mg/kg/min) (statistically different, p less than 0.05). However, when the high infusion rate group was divided into two subgroups (high, 4.7--6.8 mg/kg/min, and very high, 7.03--9.31 mg/kg/min), there was no difference in the rate of protein synthesis. When U-13C-glucose was infused during varying rates of unlabeled glucose infusion, we found that the per cent of CO2 coming from the direct oxidation of glucose rose rapidly at the lower infusion rates but reached a plateau at approximately 55% as the infusion rates exceeded 5 mg/kg/min. Addition of insulin did not affect the rate of glucose oxidation but did seem to exert a stimulatory effect on protein synthesis. It was concluded that there appears to be a maximal rate of glucose infusion, beyond which physiologically significant increases in protein synthesis and direct oxidation of glucose cannot be expected. Furthermore, there appears to be a physiological cost of exceeding the optimal glucose infusion rate, as indicated by increased rates of CO2 production during infusion as well as large fat deposits in the liver at autopsy in patients infused with large amounts of glucose.

Adolescent↗

Bile peritonitis after the use of latex rubber T-tubes.

Three cases of biliary peritonitis following the removal of a latex rubber T-tube from the common duct in the second postoperative week are reported. This is a well-recognized complication following the use of polyvinyl chloride T-tubes in biliary duct surgery, but its occurrence with latex rubber T-tubes is extremely uncommon.

Adult↗

Rupture of the bowel due to road trauma: the emergence of the "seat belt syndrome".

Seat belts have proved to be life saving for drivers and passengers involved in motor-car collisions. The number of severe head, face and trunk injuries has been significantly reduced. However, the wearing of belts has been responsible for an increased incidence of bowel rupture, in itself a potentially lethal injury if not diagnosed and treated early. There is still much to be done in improving seat belt design.

Accidents, Traffic↗

The surgical treatment of infective endocarditis.

We have reviewed 108 cases of bacterial endocarditis treated surgically since 1968. The mean age of the patients was 47.7 +/- 15.6 years (+/- SD) (range, 14-79 yr). Seventy-seven percent were male. The most common causative organisms were staphylococci (46%), streptococci viridans group (5%), and other streptococci (20%). Forty-five percent, 25%, and 13% of patients had native aortic valve, native mitral valve, or native double valve (AV/MV) involvement, respectively. Eighteen patients had prosthetic valve endocarditis. No patient underwent surgery for tricuspid valve endocarditis. Seventy-three patients were considered to have active endocarditis (AE) (positive blood or tissue cultures and/or annular abscess). The 35 remaining patients had healed endocarditis (HE). Preoperative complications in patients with either AE or HE were stroke (11%, 11%), renal failure (33%, 3%; p less than 0.001), pulmonary edema (83%, 34%; p less than 0.001), anemia (36%, 8%; p less than 0.01), and inotrope dependence (22%, 6%; p less than 0.05). Hospital mortality for native valve AE was 19.5% (11/56), and for healed endocarditis, 5.7% (2/35). Independent predictors of hospital mortality were inotrope dependence (p less than 0.001), annular abscess (p less than 0.01), pulmonary edema (p less than 0.01), and staphylococcal infection (p less than 0.05). The 5-year actuarial survival for operative survivors was 68.4 +/- 7.5% (AE) and 78.3 +/- 9.2% (HE). We conclude that the operative mortality for patients with continuing sepsis is high and that surgery should be undertaken early in staphylococcal endocarditis. If surgery is successful, then the long-term prognosis is good.

Adolescent↗

Aortic valve surgery in the elderly.

As the population ages, aortic valve replacement, particularly for aortic stenosis, has become more common. Although many patients have considerable coexisting morbidity, almost all symptomatic patients are candidates for surgery. Once symptoms develop, surgery should not be unduly delayed, because the operative mortality clearly increases in the presence of poor left ventricular function, heart failure, and New York Heart Association Class III or IV symptoms. Operative difficulties often are related to fragile tissues, a small aortic annulus, and extensive calcification of the aortic annulus and root. In the author's experience, approximately 10% of these patients undergo aortic annulus and root enlargement using pericardium. A tissue valve is the preferred prosthesis. Operative mortality for elective surgery in patients older than 80 years of age is 4-10%, depending on whether associated procedures are required (eg, coronary artery bypass grafting) or whether the patient has had previous surgery. Postoperative neurologic events are important complications that are more common in the elderly. Outcome after successful surgery is excellent, with a 5-year survival of approximately 60%. The vast majority of patients have an improved symptomatic status.

Age Factors↗