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Biomedical subjects

D W Anderson

Publications and source records attributed to D W Anderson.

At least 163 records · Page 9Linked to original sources
PubMed1968

Chlorinated hydrocarbons and eggshell changes in raptorial and fish-eating birds.

Catastrophic declines of three raptorial species in the United States have been accompanied by decreases in eggshell thickness that began in 1947, have amounted to 19 percent or more, and were identical to phenomena reported in Britain. In 1967, shell thickness in herring gull eggs from five states decreased with increases in chlorinated hydrocarbon residues.

Animals↗
PubMedDate not supplied

A prospective morphologic evaluation of hepatic toxicity of chenodeoxycholic acid in patients with cholelithiasis: the National Cooperative Gallstone Study.

A sample of 126 patients with cholelithiasis was treated with chenodeoxycholic acid (CDCA) (375 or 750 mg g.d.) for 2 years. Hepatotoxicity was assessed by sequential light (LM) and electron microscopic (EM) analysis of liver biopsies obtained before and after 9 and 24 months of therapy. Patients were without symptoms of biliary colic for 3 months prior to biopsy, less than 70 years old, and had normal tests of liver function. All light microscopy was read blindly by two morphologists, and electron microscopy by one. Only four biopsies (3%) showed severe (3+) abnormalities preventing admission to the study. On evaluation, moderate (2+) LM changes were present in less than 12% of biopsies, while milder changes (1+) were seen more frequently. No severe, dose-related abnormalities were seen in LM over the 2 years of study. However, mild changes (hepatocyte ballooning and lipofuscin, binucleate cells, glycogen nuclei, ductular proliferation, enlarged and fibrotic triads, and sinusoidal congestion) became more prevalent with time (p less than or equal to 0.01) regardless of CDCA dose, according to 1 of the 2 morphologists. Because patients with "proven" cholelithiasis for greater than 2 years (33% of the study population) did not have a greater incidence of morphologic abnormalities than those with the diagnosis for less than 2 years, it is unlikely that these changes were due to the natural history of gallstone disease. Furthermore, electron microscopic findings demonstrated worsening intrahepatic cholestasis and a lesion in two patients which was identical to that produced in animals administered lithocholic acid, the 7-alpha-dehydroxylated metabolite of CDCA. the possibility that clinically significant hepatotoxicity could develop with CDCA therapy greater than 24 months thus cannot be excluded by this study.

Adult↗
PubMedDate not supplied

Service-level costing of drug abuse treatment.

This paper presents a methodology for estimating costs of delivering specific substance abuse treatment services. Data collected from 13 programs indicate that the mean cost of residential treatment is $2,773 per patient per month, and outpatient treatment costs average $636 per patient per month. Data are presented on the cost patient per month for individual treatment and nontreatment services, average number of services, cost per unit of service, and intensity of services. In addition to their application to insurance benefit cost estimation, these data illustrate the costing of best-practice adolescent treatment consistent with a Center of Substance Abuse Treatment (CSAT) Treatment Improvement Protocol. In the emerging policy environment, detailed cost estimates like these will aid the design of cost-effective treatment programs, and serve the development of the substance abuse benefit in a health care reform insurance package.

Adolescent↗
PubMedDate not supplied

Prevalence and clinical features of epilepsy in a biracial United States population.

A need for prevalence information emphasizing racial differences prompted a door-to-door survey of all residents of Copiah County, Mississippi. The fieldwork involved a complete census and an extensive screening questionnaire inquiring about diagnoses, signs, and symptoms of neurologic disease. Residents who lived in institutions or had screening responses suggestive of epilepsy were requested to have an examination by neurologists who used defined diagnostic criteria. Prevalence day was 1 January 1978, and the survey yielded prevalence ratios of 1,043/100,000 inhabitants for epilepsy and 678/100,000 inhabitants for active epilepsy. Age-adjusted prevalence ratios were somewhat higher for males and for blacks. Of the 246 identified cases of epilepsy, 37% were judged symptomatic. The leading (putative) cause was head trauma, especially among white males. About 57% of the 246 cases had been evaluated previously by a neurologist or neurosurgeon, while 7% had never been evaluated medically before the survey.

Adolescent↗
PubMedDate not supplied

Corrections to megavoltage depth-dose values due to reduced backscatter thickness.

Multiplicative corrections for percent depth-dose values were measured for situations with nonmaximal backscatter because of reduced thickness of the irradiated phantom. Data were obtained for common clinical field sizes for a 60Co beam as well as beams from a 2.5-MV and a 4.0 MV generator. Functional forms, which summarize the results and include field size effects, depth, and thickness of the backscatter medium as variables, were obtained by regression analysis.

Cobalt Radioisotopes↗
PubMedDate not supplied

Use of a clinical accelerator in spectroscopic studies of the decay of 197Ir.

The 40-MeV direct beam bremsstrahlung irradiation facility of the Sagittaire clinical electron accelerator was used to produce 197Ir via the reaction 198Pt(lambda,p)197Ir. Gamma rays emitted in the Ir decay were detected with an intrinsic germanium system and multichannel analyzer. 106 of the spectrum peaks could be analyzed for energy, relative intensity, and half-life. Half-life results indicate that 197Ir decays from two isomers, one with half-life 6.1 +/- 0.1 min and another with half-life 8.9 +/- 0.1 min.

Gamma Rays↗
PubMedDate not supplied

Photonuclear activation ratios in fluorine compounds; an index of bremsstrahlung quality.

Samples of potassium hexafluorosilicate (K2SiF6) and polytetrafluoroethylene (C2F4)n were irradiated in the bremsstrahlung beam from a clinical linear electron accelerator at integral values of endpoint energy between 13 and 32 MeV. Sample positron activities produced by the reactions 39K(gamma, n) 38K, 19F(gamma, n) 18F, and 12C(gamma, n)11C, were determined by counting the gamma radiation. Saturation activities per target nucleus were calculated from these data. For the K2SiF6 samples, the photonuclear activation ratio (PAR) of the 7.6 min 39K saturation activity per nucleus divided by the 18F result increased by more than 20% per MeV between 15 and 21 MeV. For the (C2F4)n samples the ratio (PAR) of the 11C saturation activity per nucleus to that for 18F increased by more than 24% per MeV between 22 and 26 MeV. Quality changes caused by the lead flattening filter were easily detectable using the PAR technique. Because of the high sensitivity to bremsstrahlung spectrum changes these PAR values can serve as sensitive indices of quality for high-energy beams.

Fluorides↗
PubMedDate not supplied

Absolute kVp calibration using characteristic x-ray yields.

A spectrometer with a high-resolution room-temperature silicon detector was used to obtain spectra including characteristic x-ray peaks produced after fluoroscopic beams were incident on W, Pb, and Th absorbers. Characteristic x-ray yield points were obtained from spectra taken at several generator kVp settings which produced x rays with energy above the K-shell absorption edge for each element. A line drawn through the yield points when projected to zero yield served to locate the console setting corresponding to the actual K-absorption edge energy for each absorber. The technique is useful for precision measurement of generator kVp and absolute calibration of indirect kVp measuring devices under operational conditions.

Biophysical Phenomena↗