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Biomedical subjects

J R Lawrence

Publications and source records attributed to J R Lawrence.

150 records · Page 9Linked to original sources

The renal clearance of disopyramide after bolus intravenous injection.

Following bolus intravenous injection of disopyramide in eight normal volunteers the renal clearance of the drug appeared to fall with time. In the first two hours after injection renal clearance had a mean value of 89.0 ml min-1 and fell to 29.4 ml min-1 between 48 and 72 h. In a separate study disopyramide was given by continuous intravenous (i.v.) infusion for 8 h following a loading dose of the drug. Renal clearance of disopyramide was thus estimated hourly over three narrow serum concentration ranges in a single volunteer. The estimate of renal clearance of the drug over the first hour following the start of these infusions was considerably in excess of values obtained later in the experiments. The change in disopyramide renal clearance following bolus injection is partially time-dependent. There are, however, fallacies in calculating short-term clearance values after bolus drug injection from the venous concentration-time curve and these may partially explain the change in renal clearance of disopyramide with time.

Disopyramide↗

An assessment of a mesocosm approach to the study of microbial respiration in a sandy unsaturated zone.

Microbial respiration rates were determined through a 3.2 m thick, sandy unsaturated zone in a 2.4 m diameter x 4.6 m high mesocosm. The mesocosm was maintained under near constant temperature (18 degrees to 23 degrees C) and reached steady moisture content conditions after several hundred days. Soil-gas CO2 concentrations in the mesocosm ranged from 0.09% to 3.31% and increased with depth. Respiration rates within the mesocosm were quantified over a 342-day period using measured CO2 concentrations and a transient, one-dimensional finite-element model. Microbial respiration rates were 2 x 10(-1) micrograms C.g-1.d-1 throughout most of the system, but decreased to 10(-4) to 10(-3) micrograms C.g-1.d-1 within the capillary fringe. Microbial respiration rates were also determined in minicosms (500 g sample mass) over a range in temperatures (4 degrees to 30 degrees C) and volumetric moisture contents (0.044 to 0.37). The functional dependence of CO2 production on temperature and soil-moisture content was similar for the two scales of laboratory observation. Respiration rates in the minicosms, for temperatures and moisture contents in the mesocosm, were up to an order of magnitude greater than those determined for the mesocosm. The higher respiration rates in the minicosms, compared to the mesocosm, were attributed to greater disturbance of the samples and to shorter acclimation time in the minicosms. Extrapolating the laboratory respiration rates to field conditions yielded rates that were two to three orders of magnitude greater than rates previously determined in situ for C-horizon material. Results show that in situ microbial reaction rates determined using disturbed samples in minicosms and mesocosms yielded respiration rates that greatly exceeded field conditions. Mesocosms can, however, provide a useful environment for conducting process-related research in unsaturated environments.

Carbon↗

Thin-membrane nephropathy--a common cause of glomerular haematuria.

Thin-membrane nephropathy recently has been described as a cause of glomerular haematuria. The prognosis of the condition is unclear but it generally is considered to be benign. In a series of 92 patients with glomerular haematuria, thin-membrane nephropathy was found to be a common cause, occurring in 26 (28%) patients. Sixteen patients were women. The mean age was 42 years. Four patients had a family history of renal disease or haematuria and no patient was deaf. Haematuria had been present from six days to 30 years. Loin pain occurred in 31% of patients. Hypertension was not a feature and mild renal impairment was present in one case only, while a further three cases showed proteinuria at a level of greater than 500 mg of protein per day. Glomerular basement membranes in patients with thin-membrane nephropathy gave a mean (+/- standard deviation) width of 319 + 37 nm which was significantly (P less than 0.002) less than the control value of 394 +/- 61 nm. On the basis of clinical features and serological parameters, thin-membrane nephropathy could not be separated from other renal causes of haematuria but required careful electronmicroscopic examination of renal biopsy material to establish the diagnosis. Limited follow-up has confirmed the good prognosis of the condition.

Adult↗

Shared diabetic care.

Increased diabetic mini-clinic activity in general practice offers an unparalleled opportunity to spread the net of integrated care. Important lessons from results of published schemes must, however, be applied to harness the new energy and resources for maximum patient benefit.

Ambulatory Care↗