Biomedical subjects
Publications and source records attributed to R Mitchell.
Microembolization by platelet leukocyte aggregates is a threat to the pulmonary microvasculature when blood is transfused to patients. Those aggregates can be removed by filters (either depth filter or screen filter); their efficiency, as shown by SFP measurements is not questionable, however they are working in different ways as observed by SEM: mechanical retention and adsorption.
An investigation of the serological and biochemical properties of red cells in two unrelated British families revealed the probable presence of examples of the rare genotype EnaEn. In one family the En-modified red cells carried N-like determinants associated with s. In the other family M-like determinants associated with S were found.
The aerobic heterotrophic bacterial flora in over 200 individuals from 10 wild populations and 3 laboratory colonies of the schistosome vector snail Biomphalaria glabrata was examined. Internal bacterial densities were inversely proportional to snail size and were higher in stressed and laboratory-reared snails. The numerically predominant bacterial genera in individual snails included Pseudomonas, Acinetobacter, Aeromonas, Vibrio, and several members of the Enterobacteriaceae. Enterobacteriaceae seldom predominated in laboratory colonies. Our data suggest that Vibrio extorquens and a Pasteurella sp. tend to predominate in high-bacterial-density snails. These snails may be compromised and may harbor opportunistic snail pathogens.
A capillary assay was used to evaluate the chemotactic responses of Vibrio alginolyticus to three common algal extracellular products. Acrylate and glycolate attracted the motile marine bacterium. The peak response occurred with 10(-2) M of each chemical. Acrylic and glycolic acid also attracted V. alginolyticus, with the peak response occurring at 5 x 10(-4) M of each chemical. Higher concentrations of the organic acids resulted in a decreased response. The bacteria also displayed positive chemotaxis to dimethyl sulfide.
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A quantitative capillary assay is described for measuring chemoreception in the neritic and littoral unicellular alga Dunaliella tertiolecta. Lucite chemotaxis plates were used in the assay with 3-microliter capillaries. A Coulter Counter was employed to determine algal cell numbers. D. tertiolecta is attracted to ammonium ion with a maximum positive response at 10(-3) M. Inclusion of calcium and L-methionine in the chemotaxis medium stimulates algal chemoreception, although neither chemical is essential for motility. Attraction of the chlorophyte to ammonium is dependent on time of incubation, cell density, and pH. The optimum pH for attraction was found to be 6.25.
In the present study, population sizes of high self-renewal potential stem cells, i.e. colony forming units (CFU), and low self-renewal potential stem cells, i.e. transient endogenous colony forming units (TE-CFU) in Sl/Sld mice and their normal congenic littermates were measured and compared. By correcting for differences in the seeding efficiency 'f', it was possible to demonstrate that Sl/Sld mice suffer a deficiency of both stem cell populations. Therefore, it is concluded that the defective stromal tissue of the Sl/Sld mouse does not support normal size stem cell populations. However, as noted in the discussion, it remains an open question as to whether the defective stromal tissue supports normal erythroid differentiation at the stem cell level.
Rhythmic movements such as head-rolling, head-banging and body-rocking are seen in normal children in early life, but much more commonly in the mentally handicapped. Emotional disturbance and boredom tend to increase the movements. Various theories have been advanced to account for these stereotyped patterns. They appear to be intentional and may satisfy some inner need or allay frustations, but it is concluded that their true significance is unknown.
Selected area reflection electron diffraction has been used to determine the phases present in the reaction zones surrounding the Ag-Cu eutectic dispersant in Dispersalloy amalgam. The experiments were carried out on two kinds of specimens, (1) Dispersalloy amalgam and (2) Dispersalloy amalgam using 30, 50, 75, and 100% more mercury than found in commercially available capsules. The results show that the reaction zones in the specimens of the present investigation consist of Cu6Sn5 and Ag2Hg3. These diffraction data confirm the presence of the phases in the reaction zone which are suggested by the elemental analysis obtained by Mahler and his associates using an electron probe. Moreover, the strong intensity of the eta-Cu6Sn5 diffraction rings suggests a composition which is predominantly Cu6Sn5, again, in agreement with the electron probe data.
Our experience using the lateral simplified thoracotomy incision for most chest work other than operations requiring median sternotomy is reported. The incision provides adequate exposure, yet preserves major muscle masses and decreases the postoperative morbidity. Return of normal ipsilateral arm function appears to be hastened in the postoperative period. In addition, the incision is easier to open and close than the standard incision.
The chemotactic responses of a marine pseudomonad to steroisomers and analogues of amino acids and sugars were tested. The data reveal that the bacterium is equally attracted to D, L, and DL forms of the amino acids. In contrastr, chemical analogues of the amino acids and glucose yielded significantly lower chemotactic responses. The threshold of bacterial detection was 10(-8) M for leucine and cysteine. However, the threshold molarity of most of the analogues was higher than those of the related amino acids and sugars.
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Organic compounds are capable of repelling motile bacteria from marine surfaces. The most effective compounds were acrylamide and benzoic and tannic acids. These were active at concentrations that were not toxic to the bacteria. Repellents were incorporated in nontoxic paints and applied to metal panels. Treated panels immersed in seawater developed a bacterial film of only 10(6) bacteria per cm6 after 12 days compared with untreated panels, which had 5 times 10(12) bacteria per cm2 after the same period. Field studies confirmed the effectiveness of these repellents. The use of biological repellents provides a new approach to the control of marine fouling.
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