Biomedical subjects
K W Smith
Publications and source records attributed to K W Smith.
Pyonephrosis associated with Salmonella infection in a dog.
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The interaction of borate and sulfite with pyridine nucleotides.
The kinetics and equilibria of the borate interaction at ribose with NAD+ and NMN+ have been measured using as a chromophoric probe the perturbation effect borate has on the addition of sulfite to the 4 position of the nicotinamide ring. NAD+ and NMN+ have more favorable borate association constants than do their corresponding sulfite addition complexes. The rate of interaction of the ribose moiety with borate at low borate buffer concentration is dependent on the concentration of both borate and boric acid. At high borate concentration the rate becomes independent of borate concentration, indicating the existence of a two-step process for the interaction of NAD-sulfite with borate with a change of rate-determining step from the interaction of the ribose hydroxyl group with borate at low borate to an elimination of sulfite at high borate concentration. A linear free energy relationship with a slope of 0.94 describes an increased reactivity of the nucleotide for sulfite as the affinity of the nucleotide for sulfite increases.
Borate inhibition of yeast alcohol dehydrogenase.
Yeast alcohol dehydrogenase is inhibited competitively by borate with respect to NAD+. An unusual mechanism of competitive inhibition prevails: the competition for the substrate NAD+ by borate and enzyme. The following evidence supports this conclusion. (1) Much greater inhibition is observed with respect to NAD+ as compared with NADH as substrates. (2) Borate decreases the equilibrium constant of the overall reaction in the direction of ethanol oxidation, therefore, borate enters directly into the overall reaction rather than merely decreases the effectiveness of the catalyst. (3) The Ki values for unrelated enzyme reactions are identical for NAD+. (4) Stopped-flow experiments show burst kinetics only when NAD+ and borate are not premixed. (5) The Ki value is identical with the inverse of the borate-NAD+ complexation constant. (6) The pH dependence of the inhibitor demonstrates that only the B(OH)4-species is inhibiting. These results are consistent with the preferable binding of borate to NAD+ as compared with NADH. These two binding constants were found to be equal to 2000 +/- 60 and 130 +/- 8 M-1, respectively. In contrast to the liver enzyme, the yeast enzyme does not show pre-steady-state burst reactions in the reduction of NAD+. This would indicate that the interconversion of ternary complexes is at least partially rate limiting for the yeast enzyme.
Hyperadrenocorticism in a dog: a case report.
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Stainless steel-vinylidene fluoride resin complete hip prosthesis--evaluation in the dog.
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Small animal surgery of the future.
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Xeroderma pigmentosum. Treatment with topically applied fluorouracil.
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A comparison of gold leaf and other occlusive therapy in the management of skin ulcers.
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Wedge grafting of the canine carpus.
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Trends in the health of the asbestos worker.
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Antibiotic prophylaxis during clean neurosurgery: a large, multicenter study using cefuroxime.
Cefuroxime is a second-generation cephalosporin with in vitro activity against the organisms that are commonly associated with neurosurgical wound infections. Other properties of cefuroxime are an elimination half-life of 1.3 hours, which yields prolonged serum concentrations, and its ability to penetrate the blood-brain barrier in proportion to the degree of inflammation. A prospective, multicenter, open-label study was conducted to evaluate the efficacy and safety of cefuroxime for antibiotic prophylaxis in patients undergoing clean neurosurgery. Cefuroxime 1.5 g was given intravenously 25 to 60 minutes before surgery; for procedures lasting more than 3 hours, cefuroxime 750 mg was given intravenously 8 hours after the initial dose. Patients were examined before surgery, daily during hospitalization, and at 8 weeks after surgery. A total of 956 adults were enrolled in the study. The most common procedures in study patients were laminectomy (41.8% of patients) or craniotomy (24.3%), and the mean duration of surgery was 3.2 hours. Infection occurred in 2 (0.3%) of 592 assessable patients by the time of discharge and in 1 additional patient by the 8-week follow-up evaluation for a total of 3 (0.5%) of 560 assessable patients. Drug-related adverse events occurred in 5 (0.5%) of 956 patients. These results indicate that antibiotic prophylaxis with cefuroxime is associated with a low incidence of postoperative wound infection and is well tolerated in patients undergoing clean neurosurgery.
Is cardiovascular risk factor knowledge sufficient to influence behavior?
This paper examines the level of cardiovascular risk knowledge in the general population and the relationship between such knowledge and behavior. The following questions are addressed: (1) How informed is the general population about what persons can do to reduce their risk of cardiovascular disease? (2) How do sociodemographic factors, self-perceptions of health, and cardiovascular risk factors relate to knowledge? (3) Is there a relationship between knowledge and behavior? (4) What might explain apparent inconsistencies between knowledge and behavior? The data used in this paper derive from a random sample of 732 men and women form the greater Boston area. We assessed cardiovascular risk factor knowledge by asking respondents what specific steps a person could take to make a heart attack or stroke less likely. Risk factors (including physiological measures), sociodemographic factors, and self-perceptions of health also were measured. Results showed that respondents were most knowledgeable about the relationships of exercise and cholesterol to heart disease. Knowledge was related positively to education, being female, and exercising. When we compared knowledge with behavior, results showed that for smokers and those who were overweight, risk was related to awareness, thus suggesting that knowledge does not lead necessarily to risk-reducing behavior. Implications of these results in terms of education and prevention are discussed.
Time-of-flight methods in MR angiography.
Magnetic resonance angiography is a promising new technique for vascular imaging. MRA is based on gradient recalled acquisitions to maximize flow-related enhancement. The two major methods of MRA are time-of-flight and phase contrast. This article examines the time-of-flight method, and also includes a discussion of hemodynamics and the effects of scanning parameters.