Biomedical subjects
Publications and source records attributed to D C White.
A method for the separation and quantitative estimation of ethanolamine, dimethyl ethanolamine, and monomethyl ethanolamine derived from lipids is described. After acid hydrolysis of the lipids, the bases are extracted from the neutralized hydrolysate with t-butonol and separated by gas-liquid chromatography.
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Wright, Elizabeth A. (University of Kentucky College of Medicine, Lexington), and David C. White. Formation of a functional electron transport system during growth of penicillin-induced spheroplasts of Haemophilus parainfluenzae. J. Bacteriol. 91:1356-1362. 1966.-Penicillin in a lactose medium can be used to cause the formation of spheroplasts in Haemophilus parainfluenzae. The resulting spheroplasts grew under conditions which produced rapid formation of the electron transport system in the normal bacteria. The following elements that are incorporated into a functionally active electron transport system were formed in spheroplasts: formate and l-lactate dehydrogenases, 2-demethyl vitamin K(2), cytochromes b(1) and c(1), and the cytochrome oxidases. The catabolic enzymes aldolase, glyceraldehyde-3-phosphate dehydrogenase, and malic dehydrogenase showed slight increases in activity. These experiments indicated that spheroplasts can form a fully functional electron transport system essentially similar to that formed during normal growth. The various components of the electron transport system were formed at different rates in the growing spheroplasts.
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Caldwell, D. R. (U.S. Department of Agriculture, Beltsville, Md.), D. C. White, M. P. Bryant, and R. N. Doetsch. Specificity of the heme requirement for growth of Bacteroides ruminicola. J. Bacteriol. 90:1645-1654. 1965.-Previous studies suggested that most strains of Bacteroides ruminicola subsp. ruminicola require heme for growth. Present studies with heme-requiring strain 23 showed that protoheme was replaced by various porphyrins, uroporphyrinogen, coproporphyrinogen, certain iron-free metalloporphyrins, hemes, and certain heme-proteins containing readily removable hemes. Strain 23 utilized a wider range of tetrapyrroles than hemin-requiring bacteria previously studied. Inactive compounds included porphyrin biosynthesis intermediates preceding the tetrapyrrole stage and related compounds; uroporphyrin, chlorophyll, pheophytin, phycoerythrin, bilirubin, pyrrole, FeSO(4) with or without chelating agents; and representative ferrichrome compounds. Strain 23, two other strains representing predominant biotypes of B. ruminicola subsp. ruminicola, and one closely related strain grew in media containing heme-free protoporphyrin, mesoporphyrin, hematoporphyrin, or deuteroporphyrin, apparently inserting iron into several nonvinyl porphyrins. Porphobilinogen and porphyrin synthesis, apparently via the commonly known heme synthesis pathway, occurred during growth of heme-independent B. ruminicola subsp. brevis strain GA33 in a tetrapyrrole-free medium containing delta-aminolevulinic acid, but delta-aminolevulinic acid metabolism to porphobilinogen or porphyrins could not be detected in cells of heme-requiring strain 23 grown in the same medium with hemin added. Growth of strain 23 with uroporphyrinogen, coproporphyrinogen, or protoporphyrin IX replacing hemin suggests that part of the commonly known heme-biosynthesis pathway is present in this strain, but nutritional and metabolic evidence indicates that some or all of the enzymes synthesizing the tetrapyrrole nucleus from linear molecules are lacking or inactive.
Photon counting microscopy was used to quantify relative photon flux from 616 single sessile cells of Vibrio harveyi and 180 single sessile cells of V. fischeri. V. fischeri cells all emitted light at nearly the same level (average 15.93+/-11.48 photons/min, range 0-58.9 photons/min) when bioluminescence was induced, whereas photon flux of V. harveyi single cells was extremely variable (average 10.51+/-20.60 photons/min, range 0-211 photons/min).
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The authors analyzed laboratory costs and utilization in 3,771 cases of Medicare inpatients admitted to a New England academic medical center ("the Hospital") from October 1, 1989 to September 30, 1990. The data were derived from the Hospital's Decision Resource System comprehensive data base. The authors established a historical reference point for laboratory costs as a percentage of total inpatient costs using 1981-82 Medicare claims data and cost report information. Inpatient laboratory costs were estimated at 9.5% of total inpatient costs for pre-Diagnostic Related Groups (DRGs) Medicare discharges. Using this reference point and adjusting for the Hospital's 1990 case mix, the "expected" laboratory cost was 9.3% of total cost. In fact, the cost averaged 11.5% (i.e., 24% above the expected cost level), and costs represented an even greater percentage of DRG reimbursement at 12.9%. If we regard the reimbursement as a total cost target (to eliminate losses from Medicare), then that 12.9% is 39% above the "expected" laboratory proportion of 9.3%. The Hospital lost an average of $1,091 on each DRG inpatient. The laboratory contributed 29% to this loss per case. Compared to other large hospitals, the Hospital was slightly (3%) above the mean direct cost per on-site test and significantly (58%) above the mean number of inpatient tests per inpatient day compared to large teaching hospitals. The findings suggest that careful laboratory cost analyses will become increasingly important as the proportion of patients reimbursed in a fixed manner grows. The future may hold a prospective zero-based laboratory budgeting process based on predictable patterns of DRG admissions or other fixed-reimbursement admission and laboratory utilization patterns.
PURPOSE: Sentinel lymph node mapping using radiolabeled tracer and blue dye is widely accepted and applied for staging melanoma. Common practice involves injection of radiolabeled tracer on the morning of surgery. However, optimal timing of radiolabeled colloid injection with respect to surgery remains debated. Injection on the day before surgery would offer the advantages of increased scheduling flexibility and decreased radiation exposure to the patient and operating room staff. We hypothesized that a single injection of radiolabeled colloid given 24 hours before surgery would be sufficient and would possibly improve intraoperative sentinel lymph node identification. PATIENTS AND METHODS: Ninety-five patients with newly diagnosed cutaneous melanoma underwent injection of radiolabeled colloid and lymphoscintigraphy 18 to 24 hours before surgery for sentinel lymph node mapping and biopsy. Sixty-three patients underwent repeat imaging immediately before surgery, and the images were compared with those obtained the previous day. Intraoperative mapping utilized a hand-held gamma probe and injection of blue dye to identify sentinel lymph nodes. RESULTS: Two hundred fifty-one sentinel lymph nodes were identified by initial lymphoscintigraphy in 95 patients. Delayed imagingwithout reinjection of radiolabeled tracer compared with the initial lymphoscintigraphy demonstrated no change (71%), clarification of initial ambiguous patterns (10%), or newly identified nodes (19%). Two hundred sixty-one sentinel lymph nodes were resected, of which 79% stained blue. Microscopic metastases were present in 20 sentinel lymph nodes (8%) in 19 patients (20%). All positive nodes contained radioactivity and blue dye. CONCLUSIONS: A single injection of radiocolloid 24 hours before surgery combined with intraoperative blue dye injection identified all sentinel lymph nodes and did not miss any metastatic disease. In addition, delayed imaging may clarify initial ambiguous findings and identify additional nodes at risk for metastasis. This technique produces sentinel lymph node identification rates, harvest rates, and rates of positivity comparable to those reported with the use of injection of radiolabeled tracer on the day of surgery and greatly facilitates the technical and administrative aspects of sentinel lymph node mapping.