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Biomedical subjects

R Sullivan

Publications and source records attributed to R Sullivan.

At least 181 records · Page 10Linked to original sources
PubMed1979

Contamination of erythropoietin by endotoxin: in vivo and in vitro effects on murine erythropoiesis.

Endotoxin was detected in all erythropoietin preparations tested and was removed from four lots, without loss of erythropoietic activity, by adsorption with limulus amebocyte lysate. Comparison of adsorbed (endotoxin-depleted) and nonadsorbed (endotoxin-containing) erythropoietin preparations demonstrated significant inhibition of CFU-e and BFU-e in vitro by nonadsorbed erythropoietin at concentrations higher than 0.25 U/ml and 2.0 U/ml, respectively. CFU-e and BFU-e were inhibited significantly by readdition in vitro of 10(-5)-10(-3) mug of endotoxin per unit of limulus-adsorbed erythropoietin. Administration of saline or 6 U of nonadsorbed or adsorbed erythropoietin twice a day for 4 days of CF1 mice resulted in reticulocyte counts of 2.1%, 9.9%, and 15.9%, respectively. Nonadsorbed erythropoietin resulted in a 29% decrease in erythropoiesis, a 42% decrease in CFU-e, and a 16% increase in granulopoiesis in the marrow, whereas adsorbed erythropoietin caused a 28% increase in erythropoiesis, no significant change in CFU-e and a 19% decrease in granulopoiesis in the marrow. Both preparations resulted in marked increases in splenic erythropoiesis and granulopoiesis. The effects of adsorbed erythropoietin are similar to those produced following stimulation of hematopoiesis by endogenous erythropoietin. Hemopoietic changes induced by nonadsorbed erythropoietin in vivo and in vitro are affected substantially by contamination of the erythropoietin preparations with endotoxin.

Adsorption↗
PubMed1978

Inhibition of normal murine hematopoiesis by leukemic cells.

Inhibition of normal mouse hemopoietic stem cells by leukemic cells (C1498) was observed with use of in vitro agar and in vivo diffusion-chamber cultures. The C1498 cells were unresponsive to colony-stimulating activity, and, above a critical threshold, they inhibited normal granulocyte progenitors in agar culture. C1498 cells added to normal marrow in diffusion chambers progressively reduced granulocyte progenitors. The larger, more rapidly growing, C1498 cells showed the most inhibitory effect. Transmembrane culture of C1498 cells adjacent to normal marrow in double diffusion chambers for five to 14 days led to reduction of recovery of granulocyte progenitors (72 +/- 7 per cent of control) and pluripotent stem cells (45 +/- 7 per cent of control) from the normal marrow chambers. These results indicate that leukemic mouse cells inhibit normal mouse-marrow stem cells by releasing a diffusible substance, and this inhibition occurs primarily at the level of the pluripotent stem cell.

Animals↗
PubMed1978

Effects of actinomycin D in vivo on murine erythroid stem cells.

Low-dose actinomycin D (Acto) selectively suppresses murine erythropoiesis without decreasing erythropoietin (Ep) production. We used the plasma clot system to determine the stage of erythroid differentiation at which this inhibition occurs. Late erythroid precursors, CFU-E, and less differentiated committed erythroid stem cells, BFU-E, were assayed in CF1 mice given Acto 75-82 microgram/kg/day or saline subcutaneously for 5 days. We also assayed pluripotent (CFU-S) and committed granulocyte-monocyte (CFU-C) stem cells. Reticulocytes and marrow and spleen nucleated erythroid precursors were decreased by 99% in the Acto-treated mice; tibial marrow CFU-E were decreased by 97% and splenic CFU-E by 99%. Tibial BFU-E were not decreased by Acto, although there was a 66% diminution in splenic BFU-E. Acto increased tibial CFU-S, but splenic CFU-S and tibial and splenic CFU-C were unchanged. Thus Acto inhibits erythropoiesis by suppressing the ability of immediate committed erythroid precursors of CFU-E or CFU-E themselves to differentiate further in response to Ep. Acto does not affect survival or proliferation of the less differentiated cells--CFU-C, CFU-S, and marrow BFU-E. The suppression of splenic BFU-E in Acto-treated mice may indicate that marrow and splenic BFU-E are basically different stem cells. Alternatively, Acto treatment may impair migration of BFU-E from marrow to spleen.

Animals↗
PubMed1978

[Technology and real performances of a new circuit for new pacemaker (author's transl)].

Continuing evolution in cardiac stimulation today imposes on PM manufacturers the need to submit their products under new criteria, such as: contained dimensions, functional complexity and longer periods of patient care. PM electronic circuity plays a determinant role in meeting the best solution of these problems. Thick film hybrid technology has been chosen by the Authors because it is deemed to be the best compromise for the present goals, such as: low power consumption, low weight and small size, electrical parameters stability, functional complexity and high circuitry density, Hi-Rel performance for longer working life. A little space has been reserved for schematic diagrams of the manufacturing cycle and the applied technology; particular evidence has been shown concerning selection criteria for circuitry component selection and Hi-Rel tests for the end product. Hi-Rel and qualification standards have been selected by the Authors from MIL-STD 883 methods and AAMI-FDA pacemakers standards. Practical results of the application of this methodology can be summarised as follows: only 44-50% of the total circuits pass the complete cycle of tests and thus are used for PM manufacture; electronic failure rate in the implanted units is 0.024% failure per month.

Electronics↗
PubMed1977

Persistence of poliovirus 1 in soil and on vegetables grown in soil previously flooded with inoculated sewage sludge or effluent.

Land disposal of sewage sludge and effluent is becoming a common practice in the United States. The fertilizer content and humus value of such wastes are useful for agricultural purposes, and the recycling of sewage onto the land eliminates many of our stream pollution problems. The potential exists for crops grown in such irrigated soil to be contaminated by viruses that may be present in the sewage. Studies were initiated to determine viral persistence in soil and on crops grown under natural conditions in field plots that had been flooded to a depth of 1 inch (2.54 cm) with poliovirus 1-inoculated sewage wastes. Lettuce and radishes were planted in sludge- or effluent-flooded soil. In one study, the vegetables were planted 1 day before flooding, and in another they were planted 3 days after the plots were flooded. Survival of poliovirus 1 in soil irrigated with inoculated sewage sludge and effluent was determined during two summer growing seasons and one winter period. The longest period of survival was during the winter, when virus was detected after 96 days. During the summer, the longest survival period was 11 days. Poliovirus 1 was recovered from the mature vegetables 23 days after flooding of the plots had ceased. Lettuce and radishes are usually harvested 3 to 4 weeks after planting.

Poliovirus↗
PubMed1975

Collaborative study of the glass wool filtration method for the recovery of virus inoculated into ground beef.

A method for estimating viral population levels in ground beef was studied collaboratively in 7 laboratories. The collaborators recovered virus from 6 inoculated samples. Three samples were replicates of the high virus concentration 050 plaque-forming units (pfu)/g) and 3 replicates represented the low concentration (10 pfu/g). Six of the 7 collaborators recovered acceptable levels of virus from the samples. The per cent of variation was 30.6 for the high concentration and 18.5 for the low concentration. Collaborators did not differ from one another significantly in the results obtained for the 10 pfu/g samples, but results from one collaborator were significantly low for the recovery of virus from the 50 pfu/g samples. The results indicate that the glass wool filtration method is adequate for the detection of a number of viruses that may be found in foods. The method has been adopted as official first action.

Animals↗
PubMed1973

Gamma radiation inactivation of coxsackievirus B-2.

The radioresistance of coxsackievirus B-2 was studied when the virus was suspended in Eagle minimal essential medium, distilled water, cooked ground beef, and raw ground beef and irradiated at various temperatures in a cobalt-60 gamma radiation source. The number of surviving viruses at given doses of radiation was determined by a plaque assay system. All destruction curves indicated a first-order reaction. When the virus was irradiated in minimal essential medium at temperatures of -30, -60, and -90 C, D values (in Mrad) were 0.69, 0.59, and 0.64, respectively. When the virus was suspended in water and irradiated at -90 C, the D value was 0.53. Cooked ground beef containing the virus was irradiated at temperatures ranging from 16 to -90 C. The D values were 0.70 (16 C), 0.76 (0.5 C), 0.68 (-30 C), 0.78 (-60 C), and 0.81 (-90 C). Raw ground beef containing the virus was irradiated at -30, -60, and -90 C, and the D values were respectively 0.75, 0.71, and 0.68. The D values indicate that the rate of viral inactivation was dependent on the suspending menstrum.

Analysis of Variance↗
PubMed1973

Comparison of methods for the recovery of virus inoculated into ground beef.

Various methods for the recovery of virus inoculated into ground beef were investigated in an attempt to develop a sensitive system that could be used to detect viral contaminants in market foods. A 100-g sample, inoculated with poliovirus 1, was suspended in 150 to 900 ml of Eagle minimum essential medium, pH 8.5, and mixed in either plastic bags or plastic cups on a mechanical shaker. The particulate materials were removed by means of cheese cloth, glass wool, woven fiber glass, or low-speed centrifugation. Large volumes of fluid were concentrated by ultrafiltration. Microbiological contamination was controlled by high antibiotic concentrations or by filtration. Quantitative plaque-forming-unit recovery of the virus was determined by utilizing an agar overlay technique on Vero cell cultures. The data indicated that from 20 to 50% of the seeded virus could be recovered from a 100-g sample of ground beef. The glass wool and woven fiber glass methods were the most effective, with recovery of approximately 50% of the inoculated virus.

Acetates↗
PubMed1971

Inactivation of thirty viruses by gamma radiation.

Decimal reduction values (D value) for 30 viruses were determined. The weighted D values of the viruses suspended in Eagle's minimum essential medium ranged from 0.39 to 0.53 Mrads. It was necessary to increase the radiation dose by a factor of >3 to inactivate virus suspended in Eagle's minimum essential medium as compared to the same virus suspended in distilled water. The destruction rate curves were of a first-order reaction.

Amino Acids↗
PubMed1971

Thermal resistance of certain oncogenic viruses suspended in milk and milk products.

Thermal destruction rate curves were determined for adenovirus 12, reovirus 1, and herpes simplex virus in sterile milk, raw milk, raw chocolate milk, and raw ice cream mix. At 40 to 60 C, the curves were asymptotic to the base line. At 65 C, which is near the pasteurization standard, the curves approached a first-order reaction. Thermal resistance studies, by means of in vivo assays, of Moloney and Rauscher leukemia viruses and Moloney and Rous sarcoma viruses indicated that Rous sarcoma was the most resistant. A comparison of the 12D processes of Rous sarcoma virus, reovirus 1, adenovirus 12, and herpes simplex virus in ice cream mix (the most protective of the suspending menstrua studied) with the U.S. Public Health Service pasteurization standard indicated an adequate safety factor in current pasteurization practices.

Adenoviridae↗