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Biomedical subjects

S G Axline

Publications and source records attributed to S G Axline.

10 recordsLinked to original sources
PubMed1977

Amikacin therapy. Use against infections caused by gentamicin- and tobramycin-resistant organisms.

Amikacin sulfate was used in 24 treatment courses for 25 serious infections caused by aerobic or facultative anaerobic Gram-negative organisms resistant to numerous drugs. Sites of infection included urinary tract (11 cases), pleuropulmonary (6 cases), primary bacteremia (5 cases), and miscellaneous (3 cases). Serratia marcescens and Pseudomonas sp accounted for 73% of the isolates. The mean minimal inhibitory concentration (MIC) of these organisms to amikacin was 3.6 microgram/ml; to gentamicin, 39 microgram/ml; and to tobramycin, 32 microgram/ml. The mean peak serum concentration of the drug was 20.8 microgram/ml. Eleven patients were critically ill at the onset of therapy, and seven patients were bacteremic. The overall favorable response rate was 80%. The most serious side effect was ototoxicity, which occurred in three of 15 patients examined by serial audiometry.

Adult↗
PubMed1977

Enzymatic basis for bioenergetic differences of alveolar versus peritoneal macrophages and enzyme regulation by molecular O2.

Alveolar macrophages (AM) and peritoneal macrophages (PM) originate from common precursor cells, but function in different O2 environments. In the present studies, the impact of different O2 tensions on cell metabolism has been quantitatively determined, an enzymatic basis for these differences established, and a mechanism which regulates enzymatic differences demonstrated. O2 consumption and lactate production were compared in rabbit AM and PM in air and nitrogen. In air, AM demonstrate significantly greater O2 utilization. In nitrogen, (where glycolysis is the major source of energy provision) lactate production is two- to threefold greater in the PM. A comparison of several enzymes of energy metabolism in AM and PM indicate that one basis for the differences in cell energetics is a difference in activity of key enzymes of both the oxidative phosphorlyative and the glycolytic sequences. Exposure of cultivated AM to hypoxic conditions results in changes in the activity of these enzymes such that the AM closely resembles the PM. A key enzyme in oxidative phosphorylation (cytochrome oxidase) shows decreased activity and reaches values similar to those found in the PM. A key enzyme in glycolysis (pyruvate kinase) shows increased activity to values resembling those found in the PM. These alterations in enzyme pattern occur in isolated cell systems, suggesting that molecular O2 modifies the intrinsic cellular regulation of some enzymes of energy metabolism. Alterations in O2 tension may lead to alterations of the rate of biosynthesis and (or) the rate of biodegradation of key enzymes involved in oxidative phosphorylation and glycolysis. In turn, the alteration of enzyme patterns leads to a more suitable bioenergetic pattern as a function of O2 availability.

Animals↗
PubMed1976

Clearance of gentamicin during hemodialysis: comparison of four artificial kidneys.

The effects of four types of artificial kidney on dialyzer clearance rates and serum pharmacokinetics of gentamicin were compared. In 19 patients undergoing chronic hemodialysis, the mean (+/-SE) interdialysis half-life of gentamicin in serum was 49.3 +/- 3.5 hr, whereas during dialysis this value was reduced to 10.0 +/- 0.7 hr. The mean half-life of gentamicin in serum at conventional flow rates for the Hollow Fiber Kidney, Kiil, Gambro, and Coil dialyzers was 11.3, 10.9, 8.2, and 7.4 hr, respectively, and the mean values for clearance of gentamicin were 26,28,42, and 48 ml per min, respectively. For all dialyzers, rates of clearance of gentamicin increased linearly with plasma flow rate over the flow range studied. The Gambro and Coil dialyzers had significantly higher rates of clearance of gentamicin from serum (P less than 0.05) than the Hollow Fiber Kidney and Kiil dialyzers over a wide range of clinically useful plasma flow rates (119-300 ml per min), whereas the Kiil dialyzer cleared gentamicin more effectively (P less than 0.05) than the Hollow Fiber Kidney dialyzer over a more limited interval (117-177 ml per min). Therapeutic recommendations for patients undergoing hemodialysis were made in light of current findings.

Anti-Bacterial Agents↗
PubMed1976

Computerized consultation system for selection of antimicrobial therapy.

Mycin, a computer-based consultation system which provides to physicians antimicrobial therapy recommendations for patients with bacterial infections, is described. The consultation program arrives at therapeutic decisions using a built-in knowledge base as well as patient data entered by the physician. The system is capable of explaining its recommendations and answering questions about its reasoning process. The system's knowledge can be updated and corrected easily by infectious disease experts. At present the system is operational within a research setting; its routine use in a clinical setting will require further evaluation of its reliability and effectiveness.

Anti-Infective Agents↗
PubMed1975

Phagolysosome formation in normal and colchicine-treated macrophages.

Intracellular lysosomal fusion has been evaluated in cultivated mouse peritoneal macrophages by measurement of transfer of acid phosphatase to polyvinyltoluene (PVT)-containing phagolysosomes. Enzyme transfer was found to be directly and significantly related to the uptake of PVT and to be independent of time allowed for phagolysosome formation over time periods of 15 min to 18 h. In addition, the extent of transfer of lysosomal enzyme to phagolysosomes was unaffected by treatment of the cells with 10(-6) M colchicine, a dose which eradicates morphologically identifiable microtubules in this cell type within 2 h. The data indicate that intracellular fusion of lysosomes with phagosomes in the macrophage does not require formed microtubules and suggest that fusion occurs promptly after interiorization of inert particles.

Acid Phosphatase↗
PubMed1975

Colchicine effects on lysosomal enzyme induction and intracellular degradation in the cultivated macrophage.

The effects of colchicine on lysosomal fusion and lysosomal enzyme induction in the cultivated mouse peritoneal macrophage have been examined. Colchicine (10- minus 6 M), but not lumicolchicine, inhibited lysosomal enzyme induction by both phagocytic and pinocytic stimuli. In addition, the drug significantly retarded pinocytic uptake of [3-H] sucrose and transport of the amino acids [3-H] alpha aminoisobutyric acid and L-[3-H] leucine. In contrast, lumicolchicine had no effect on pinocytosis or amino acid transport. Thus, a role for intact microtubules in lysosomal enzyme induction, pinocytosis, and amino acid uptake in these cells is suggested. That colchicine inhibited lysosomal enzyme induction by phagocytic stimuli under conditions in which pinocytosis contributed little to the enzyme rise indicated that inhibition of pinocytosis was unlikely to account for colchicine effects on lysosomal enzyme induction. Effects of colchicine on degradation of phagocytized and pinocytized substrates were examined to determine if intact microtubules are required for fusion among lysosomes, pinosomes, and phagosomes. Colchicine did not alter the rate of intracellular digestion of radiolabeled bacteria by the cultivated macrophage. Similarly, it had no effect on enzymatic hydrolysis of intracellular [3-H] sucrose resulting from uptake of exogenous invertase. The finding that colchicine had no effect on the functional consequences of fusion of lysosomes with endosomes suggests that intact microtubules are not required for fusion among these constituents of the vacuolar apparatus.

Acid Phosphatase↗