Biomedical subjects
Publications and source records attributed to D E Brown.
Guidelines for the assessment of the chronically painful wrist are described, including the uses and limitations of plain roentgenograms, arthrography, CT, tomography, and cineradiography. A careful review of these studies is emphasized.
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Progressive redistribution of pulmonary blood flow to the lung apices occurs with increasing degrees of left ventricular failure, and correlates with increasing pulmonary capillary wedge pressure (PCWP). If similar changes in pulmonary blood volume (PBV) occur, then technetium-99m equilibrium blood pool scintigraphy, by assessing relative distribution of PBV, may allow prediction of PCWP. Therefore 30 patients being monitored with pulmonary artery balloon flotation catheters underwent imaging. PCWP was compared with the average radioactive count density arising from apical (A) and basal (B) regions of interest within the right lung, expressed as an A/B ratio. Correlation was strong for patients imaged erect, either posteriorly (r = 0.864, p = 0.001) or in the 45 degrees left anterior oblique position (r = 0.842, p = 0.001), and only slightly less impressive for patients imaged supine (r = 0.678, p = 0.001). Especially when imaging was performed with patients erect, an A/B ratio greater than unity identified with high sensitivity (100%) and specificity (83 to 88%) an abnormally elevated PCWP (greater than 12 mm Hg). Moreover, directional changes in the A/B ratio reflected concomitant changes in PCWP after intervention. Thus, analysis of lung A/B radioactive count ratios obtained by equilibrium blood pool scintigraphy may be used to evaluate PCWP.
The diagnosis of active pericardial bleeding has traditionally depended on an invasive documentation by needle aspiration, angiography, or direct inspection. Blood pool scintigraphy performed in 2 patients just before and after the development of hemopericardium revealed unique images in which acute pericardial bleeding manifested itself by an additional blood pool adjacent to the cardiac chambers. With appropriate attention to technical factors, such distinctive images should be highly specific for active bleeding into the pericardial sac.
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The effect of actinomycin D on the sensitivity of endotoxin-responsive (C3HeB/FeJ) and endotoxin-unresponsive (C3H/HeJ) mice to challenge with purified lipopolysaccharide (LPS) of Escherichia coli strain O55:B5 was examined using an experimental protocol of adoptive transfer of lymphoid cells into lethally irradiated recipients. Earlier results--that in the absence of actinomycin D, the ability of LPS to cause a lethal response in the immunologically chimeric mice reflected the phenotypic response of the donor lymphoid cells--were confirmed. Simultaneous administration of actinomycin D to endotoxin-responsive C3HeB/FeJ mice increased by several orders of magnitude the sensitivity of these mice to the lethal effects of LPS. Determinations of 50% lethal doses in the presence of actinomycin D indicated that immunologic chimeras were sensitive to lethal effects of LPS if either the donor or the recipient phenotype was LPS-responsive. Thus, the mechanism(s) of host response to LPS in the presence of actinomycin D may not be identical to those elicited in untreated mice.
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Physicochemical data for patent blue violet dye (I) are reported. The pKa for protonation of the first diethylanilino group was 2.78 +/- 0.03. The absorptivity values calculated for a 1% (w/v) solution of previously dried I at pH 7.4 were 1650, 170, and 250 at 638, 412, and 309 nm, respectively. A table of wavelength maxima and observed solution color as a function of pH and Ho and five spectra of I at certain pH and Ho values are included. The solution chemistry of I is explained, and a scheme showing its two protonated carbonium ions and its triphenylcarbinol derivative is presented. The distribution coefficients of I in n-octanol or chloroform and pH 7.4 phosphate buffer systems were 0.013 and 0.12, respectively. The approximate solubilities at 25 degrees of I in six organic solvents and the solubility analysis of I in distilled water are reported. Results of the latter analysis suggest that I forms a lyotropic mesophase in high aqueous concentrations. Compound I is poorly lipid soluble. Samples of 1.000% I in 0.9% NaCl, formulated with and without 1% (v/v) benzyl alcohol and autoclaving, varied not more than 5% from the initial I content during storage in the dark and under constant fluorescent light at 25 +/- 5 degrees for 20 months. Data from the TLC of I in several eluents indicated a high degree of purity of the dye. The half-lives for the loss of color in 5 X 10(-4)% I solutions in potassium hydroxide solutions of pH 13.7, 12.7, 11.3, and 10.0 were 1.2 hr, 17.0 hr, 9.5 days, and 180 days, respectively. The fraction of I bound to 4% (w/v) human serum albumin at 37 degrees and pH 7.4 ranged from 0.05 to 0.83, corresponding to unbound I in the postdialysis concentration range of 1.7 X 10(-4) to 2.0% (w/v). A Scatchard plot of the albumin binding data of I revealed one high-affinity binding site, K = 6235 M-1, and five low-affinity sites, with average affinity constants of 33 M-1. The data support the fact that the spectrophotometric determination of I at 639 +/- 2 nm appears to comprise a stability-indicating assay.
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A surgical preparation allowing for the determination of apparent absorption in the conscious, unrestrained pig is described. The technique allows the collection of blood from the hepatic portal vein and vena cava, as well as the simultaneous determination of rate of flow through the portal vessel. A chronic electromagnetic blood flow probe is placed around, and a mechanical, hydraulically activated sampling needle attached to, the hepatic portal vein. An indwelling catheter is placed within the vena cava. By simultaneously determining nutrient concentration of hepatic portal and vena cava blood and then multiplying their difference by the rate of blood flow through the hepatic portal vein, one can make a point-in-time estimate of apparent absorption from the gastrointestinal tract.
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PSRO adopted a methodology in which first five days of hospitalization were exempted from utilization review. Substantial savings and expanded concurrent review resulted.
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The generation of PSRO impact statements cannot simply be a "fill in the formula" routine. A health care system is not a simple environment, and narrow approaches to documenting change usually will not suffice. Instead, one would hope that future PSRO impact studies will take into consideration at least the concerns discussed here, as well as many others. As demonstrated in the New Mexico PSRO experiment, PSROs may not be able to demonstrate cost savings given the enormity and fragmentation of the health care environment. Such a conclusion should not result in a declaration of the PSRO program's failure but, instead, should serve to redirect the program's emphasis toward quality assurance, for which even the OPEL study noted impact.
Continuous culture studies have been carried out growing Trichoderma viride QM 9123 in a 10 liter stirred fermentor on a medium containing commercial glucose as the carbon source. Experiments were carried out at 30 degrees C and at three controlled pH values of 2.5, 3.0, and 4.0 over a range of dilution rates from 0.01 to 0.11 hr-1. Steady-state values of cell, glucose, and cellulase concentration oxygen tension, and outlet gas oxygen partial pressure were recorded. Values of maximum specific growth rate, endogenous metabolism coefficient, Michaelis-Menten coefficient, yield and maintenance coefficient for glucose were derived and correlated the effect of the hydrogen ion concentration. Specific oxygen uptake rates were correlated with specific growth rates and absorption coefficients were shown to be a function of dilution rate independent of pH. Some data on cellulase biosynthesis were examined and correlated in terms of a maturation time model.
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