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Biomedical subjects

W Sanders

Publications and source records attributed to W Sanders.

At least 19 recordsLinked to original sources
PubMed2001

Potential of anaerobic digestion of complex waste(water).

Although they differ greatly in origin complex waste(water)s mainly consist of proteins, lipids, carbohydrates and sometimes lignin in addition. Hydrolysis is the first and generally rate-limiting step in the process of anaerobic digestion of particulate organic substrates. Hydrolysis of particulate polymers can be described by Surface Based Kinetics, but for use in practice the empirical first order relation is advised. Unlike the hydrolysis of protein and carbohydrate, lipid hydrolysis is hardly occurring in the absence of methanogenesis. The latter is probably a physical rather than a biological process and affects the choice for either a one- or a two-step (phase) anaerobic reactor. In the chain of collection and transport, complex wastes often become complex wastewaters simply because of dilution. Dilution not only changes the reactor technology to be applied but also complicates the post-treatment and possibilities for resource recovery. Combining concentrated with diluted waste streams will almost always end up in much more complicated treatment technologies.

Bacteria, Anaerobic↗
PubMed1991

Anatomic and machine projection angles of various radiographic imaging systems used for cardiac angiography.

Quantitation of coronary artery dimensions in serial angiographic studies requires an awareness of the variety, complexity, and implications of radiographic imaging equipment used for coronary arteriography. Recognition of the geometric complexities inherent in angiographic imaging systems is important in understanding complex image rotations and ensuring identity of projections when serial comparison is desired. Tables, figures, and formulae are provided to permit translation of machine angles into patient reference angles and vice versa.

Angiography↗
PubMed1991

Coronary artery quantitation and data management system for paired cineangiograms.

A computerized system designed to optimize the quantitation of coronary vessels on 35 mm cineangiograms is described and validated. Because the system has two cine film digitizers, it processes paired coronary arteriograms for the evaluation of serial changes in coronary arteries. A database system was specifically designed for the storage of coronary artery quantitation data which resides on a file server in a local area network and may be accessed by multiple workstations. In radiographic phantom studies of nine contrast-filled lucite cylinders of known size, the overall accuracy and precision for the measured diameters were 0.069 mm and 0.066 mm respectively. Measurements of minimum diameter and percent diameter stenosis of 21 coronary lesions selected from 17 routine cineangiograms showed high degree of intraobserver and interobserver reproducibility.

Cineangiography↗
PubMed1990

[The pneumoportogram, a rare finding in septicemia due to an intra-abdominal abscess].

A man aged 73 is described with radiologically revealed air in the portal vein, a peumoportogram, on the basis of intra-abdominal sepsis. Characteristic of this finding are the air shadows extending far into the periphery of the liver in contrast to an air cholangiogram. It is an ominous sign, mostly secondary to severe intra-abdominal pathology such as ischaemic bowel necrosis, peritonitis or abscesses. Treatment should be aimed at these causes. Prognosis depends on the underlying pathology.

Abscess↗
PubMed1990

Evaluation of catheters and metallic catheter markers as calibration standard for measurement of coronary dimension.

Measurement of coronary dimension requires an accurate and reproducible dimensional reference. Angiographic catheters are frequently used for this purpose. We measured the angiographic diameters of a broad range of diagnostic and angioplasty guiding catheters by using two commonly used edge-detection algorithms. Angiographic diameters are significantly less than true catheter outer diameter. Therefore the use of contrast-filled catheters as a dimensional reference may lead to considerable error in vessel measurement with overestimation of absolute dimension. Tables of reference values for multiple catheter as calibration standard, tested under a variety of angiographic conditions. The metallic-tipped marker was found to have a better degree of reproducibility than catheters. These findings have implications for studies employing serial measurements of coronary artery dimension and for the clinical practice of estimating vessel diameter for choice of balloon size during angioplasty.

Calibration↗
PubMed1990

Vasodilatory effects of lidocaine on epicardial porcine coronary arteries.

To investigate the mechanism of lidocaine's effect to cause vasorelaxation, swine epicardial mid-right coronary arterial rings were placed under constant (5 g) tension in a muscle bath, precontracted with 35 mmol/l KCl and exposed to increasing concentrations of lidocaine (3-2,000 micrograms/ml). At a concentration of 10 micrograms/ml, mild vasoconstriction occurred, increasing tension 1.9 +/- 0.1% above baseline. Vasodilation began to occur at 30 micrograms/ml and was maximal at 2,000 micrograms/ml, reducing tension 97.5 +/- 0.2% below baseline. Vasodilation was not altered significantly by removal of endothelium or by pretreatment with propranolol or indometacin.

Animals↗
PubMed1989

Increased hydrogen peroxide in the expired breath of patients with acute hypoxemic respiratory failure.

Acute hypoxemic respiratory failure (AHRF) can result from diverse lung insults. Toxic oxygen metabolites have been implicated in this clinical condition and in animal models of pulmonary edema. Hydrogen peroxide (H2O2), an oxygen metabolite, mediates tissue injury. We measured H2O2 levels by a spectrophotometric technique in the breath condensate of 68 mechanically ventilated patients; 13 patients with normal lungs undergoing elective surgery had no such detectable levels of H2O2. Fifty-five patients in the ICU meeting criteria for the adult respiratory distress syndrome (ARDS) had a higher concentration of H2O2 in the expired breath condensate than ICU patients without pulmonary infiltrates (2.34 +/- 1.15 vs 0.99 +/- 0.72 mumol/L, p less than 0.005). This marker had a sensitivity of 87.5 percent and a specificity of 81.3 percent in separating the two patient populations. Patients with AHRF and focal pulmonary infiltrates who did not meet criteria for ARDS also had higher concentrations of H2O2 (2.45 +/- 1.55 mumol/L) than patients without pulmonary infiltrates (p less than 0.001). No difference was observed between the expired H2O2 concentrations of patients with ARDS or patients with focal pulmonary infiltrates. Patients with brain injury or sepsis tended to have higher levels of H2O2 regardless of lung pathology. Increased levels of H2O2 are detected in the expired breath of ICU patients with focal lung infiltrates and in ARDS patients, which is consistent with the hypothesis that oxygen metabolites participate in the pathogenesis of ARDS and other forms of AHRF.

Breath Tests↗
PubMed1988

Prediction of risk of anterior myocardial infarction by lesion severity and measurement method of stenoses in the left anterior descending coronary distribution: a CASS Registry Study.

To assess the 3 year risk of anterior myocardial infarction in patients with left anterior descending coronary artery territory disease (30 to 100% stenosis), National Heart, Lung, and Blood Institute (NHLBI) Coronary Artery Surgery Study (CASS) registry patients were identified who were 1) medically treated, and 2) had evidence of viable anterior myocardium at the time of baseline angiography. Prospectively, 118 patients having an anterior infarction within 3 years of baseline angiography were identified from annual follow-up of 4,535 medically treated patients who had left anterior descending coronary artery disease and viable anterior myocardium. From the large residual pool of patients without infarction, 141 were randomly selected from a stratified matrix to represent the entire group. The maximal percent stenosis was estimated by the CASS multiple angiographers, by a current single observer rereading and by contemporary computer measurement techniques. Absolute lumen dimension was assessed by computer measurement. The 3 year risk of anterior infarction was 2% for patients with their most severe left anterior descending stenosis less than 50%, 6% for patients with one such stenosis greater than or equal to 50% and 11% for patients with two or more such stenoses greater than or equal to 50% (p less than 0.02). Stenoses of 90 to 98% had the highest (15%) 3 year risk of anterior myocardial infarction. The three methods used to measure maximal percent stenosis differed little with regard to their predictiveness. Absolute lumen dimension was less predictive of risk. These results may provide a more rational basis on which to base coronary revascularization decisions.

Clinical Trials as Topic↗
PubMed1988

New methodologies for studying the prevention of atherosclerosis.

To determine if multiple risk factor modification favorably alters the rate of progression of coronary atherosclerosis, 300 patients with established atherosclerosis have been randomized into a clinical trial; 155 to usual care and 145 to special intervention. All patients have medical/risk examinations at baseline and annually for 4 years. The special intervention patients undergo aggressive risk factor management with emphasis on lipoprotein modification, dietary management, smoking abatement, blood pressure control, weight loss and increased physical activity. To measure progression of atherosclerosis, a quantitative, computer-assisted coronary arteriographic system was developed to analyze the baseline and 4-year follow-up arteriograms. This procedure uses a catheter with a metallic calibration cylinder at its tip to determine absolute artery size and automated computer edge detection techniques to define the internal border of the artery. The analysis system detects artery borders using changes in cine film density and measures distances between these borders. For each segment the minimum, maximum and mean diameters are measured and percent stenosis and atheroma area calculated. This system provides precise and reproducible measures of coronary artery segment diameter. Using this technique, we estimate a 33% reduction in the rate of coronary artery progression over 4 years, defined as mean segment diameter, can be detected at a power of 0.80 and an alpha of 0.05 (one tailed test) with a sample size of 120 in each of 2 groups.

Coronary Angiography↗
PubMed1986

Optimal detection of the progression of coronary artery disease: comparison of methods suitable for risk factor intervention trials.

To assess the best method of quantitating progression of coronary disease, we studied four measurements in 114 coronary segments from 35 medically treated patients from whom angiograms were obtained 5 years apart. Only stenoses of less than 70% that were visualized in nearly identical projections on both angiograms were evaluated. Vessel edges were measured by use of catheter calibration and an automated computer algorithm yielding two "absolute dimensions" (mean and minimum diameters) and two measurements (percent stenosis and atheroma area) that required a "normal reference" diameter. The coefficient of variation for repeated segment measurements was less for mean and minimum diameter than for percent stenosis and area of atheroma. The best measure of progression of coronary disease as determined by t test comparison of different methods was the change in mean diameter over time (6.7 +/- 14.1% decrease), whether calculated on a per coronary segment or per patient basis (p less than .001). Based on this measurement and its standard deviation of progression of coronary disease in this patient subset with relatively benign disease, it is estimated that 470 patients per group would be required for an interventional study to demonstrate a 33% reduction in disease progression (207 patients for 50% reduction) at a 95% confidence level and 90% power.

Cardiac Catheterization↗
PubMed1978

Comparison of BL-S786 with cephalothin, cefamandole and cefoxitin in vitro and in treatment of experimental infections in mice.

The activity of BL-S786 was compared to that of cephalothin, cefamandole and cefoxitin in vitro and in treatment of experimental infections in mice. In broth dilution tests, the activity of BL-S786 was less than cephalothin or cefamandole against Staphylococcus aureus and less than cefamandole or cefoxitin against Haemophilus influenzae. BL-S786 and cefamandole were the two most active drugs against cephalothin-sensitive Enterobacteriaceae. In tests with cephalothin-resistant Enterobacteriaceae, BL-S786 was generally less active than cefamandole but more active than cefoxitin against all strains except Proteus and Providencia. Regardless of the comparative in vitro activity of the four drugs, BL-S786 was the most effective drug in treatment of mice lethally infected with Enterobacteriaceae. Protection from lethality was associated with clearance of bacteremia by each of the four drugs. In several tests where in vitro activity was not predictive of in vivo efficacy, selection of resistance in vivo was found to have occurred.

Animals↗