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Biomedical subjects

D Emerson

Publications and source records attributed to D Emerson.

35 records · Page 2Linked to original sources
PubMed1991

Experimental apparatus for selection of adherent microorganisms under stringent growth conditions.

A bioreactor apparatus is described for studying bacterial attachment. A cyclic, on-off, flow regime was imposed within the apparatus. Model calculations illustrate the utility of this flow pattern in the selection and maintenance of slow-growing, adherent organisms. The apparatus is believed to have general utility in testing bacterial attachment influenced by many types of experimental or environmental constraints, including variations in fluid dynamics, presence of toxic substances (metals or organics), nature of the substratum surface, concentrations of limiting nutrients, and competition between bacterial strains. As an example application, the apparatus was employed to test 14 bacterial strains for surface attachment in a nutrient-limited growth medium. The medium was developed, using the chemical equilibrium program MINEQL, for planned studies of biofilms in a solution with a chemically defined composition that permits calculation of trace metal speciation. The apparatus was used to select organisms with growth and attachment characteristics that could not be evaluated by conventional batch, or chemostat, culture conditions. When supplied with acetate, pyruvate, or succinate as a carbon and energy source, the gram-negative strains Pseudomonas cepacia 17616 and Zoogloea sp. WGO4 showed superior attachment characteristics to glass surfaces in the chemically defined medium but only moderate fluid-phase growth. The gram-positive Arthrobacter sp. strain 9G4D and gram-negative species P. pickettii and Zoogloea sp. WNJ8, when supplied with pyruvate as a carbon and energy source, were capable of superior growth in the fluid phase but formed only a low to moderate biofilm surface coverage.

Bacteria↗
PubMed1989

Transabdominal chorionic villus sampling for first-trimester prenatal diagnosis.

We report here our technique and initial experience with transabdominal chorionic villus sampling for first-trimester prenatal diagnosis at the University of Tennessee, Memphis. Eighty-seven patients underwent transabdominal chorionic villus sampling between 9 and 12 menstrual weeks of pregnancy. Sufficient chorionic villi (greater than or equal to 5 mg) were obtained from 83 of the 87 patients (95.4%); in 73 (88%) of the 83 successful samplings only a single needle passage was required. In one case a 47,XX, +21 complement was diagnosed; the patient elected to terminate the pregnancy and the diagnosis was confirmed in the abortus. In a second case a 46,XX,rcp(15;21)(p11;q21) woman had a fetus who also had the same balanced translocation. In a third case nonmosaic 47,XX, +16 was detected in both direct preparations of cytotrophoblast cells and cultured mesenchymal core cells. Amniocentesis performed at 15 weeks showed a normal 46,XX complement. The pregnancy continued, and the patient was delivered at term of a healthy female infant. Two spontaneous fetal losses occurred in this series, and one woman underwent an elective abortion after receiving the results of a 46,XX complement. To date, 39 of the women have been delivered and all infants are doing well; the remaining 44 pregnancies are continuing uneventfully. We conclude that transabdominal chorionic villus sampling can be a useful alternative to transcervical chorionic villus sampling, particularly when transcervical sampling is contraindicated (e.g., active genital herpes) or where the transcervical approach would be technically difficult.

Adult↗
PubMed1989

Transabdominal chorionic villus sampling in a patient with a bicornuate uterus.

In our preliminary experience with transabdominal chorionic villus sampling, we encountered a patient with a uterus bicornis bicollis and anterior fundal placenta, which posed particular technical difficulties for the transcervical approach, but in whom sampling was easily accomplished by the transabdominal route. A description of this case, as well as a discussion of our technique and experience to date, is provided.

Abdomen↗
PubMed1986

Antibodies to neurofilament protein in retinitis pigmentosa.

Antibodies reactive with heterologous neural tissue were detected by indirect immunofluorescence microscopy in the sera of 17 of 34 patients with retinitis pigmentosa, one of 30 normal control sera, and a variable percentage of sera derived from subjects with diverse ocular and neurological diseases. These antibodies were also found both in disease-free first degree relatives and in spouses of patients with retinitis pigmentosa. Analytical sodium dodecyl sulfate-polyacrylamide gel electrophoresis of human spinal cord components followed by immunoblots with sera under study revealed that the serum antibody was specific for the high molecular weight protein subunit of neurofilaments. No correlation was found between the presence of these antibodies and other immunological and clinical parameters in retinitis pigmentosa. These findings suggest that release of piled-up neurofilaments from damaged neurones in retinitis pigmentosa triggers B lymphocytes autoreactive to neurofilament antigens.

Adult↗
PubMed1986

Antenatal sonographic findings in trisomy 18.

The clinical and sonographic findings of trisomy 18 are varied. Fifteen cases of trisomy 18 were retrospectively reviewed with attention to demonstrable antenatal sonographic features. Certain combinations of findings, particularly in the third trimester, seem highly suggestive of this diagnosis. A late antepartum diagnosis is warranted because of the poor prognosis.

Abnormalities, Multiple↗
PubMed1984

Delivering educational programs via telephone: teleconferencing.

Professionals participating in poison network programs not only need to maintain technical and scientific updatedness but also need to develop colleagual relationships between and among themselves regardless of geographic location. In an effort to achieve both objectives in a cost-effective and cost-efficient manner, we have explored the use of telephone conferencing. With the "speaker" located in Seattle, and the connecting bridge established and manned in Boise, Idaho, three one and one half hour presentations were brought to 90 sites scattered throughout rural and semi-rural Idaho; and received by more than 1,200 attendees. Hosting groups of 8-20, each location had a speaker phone enabling two-way communication to take place, i.e. they could hear the speaker and individuals could interrupt and address the speaker. Moreover, each location had a slide projector and duplicated set of slides used by the speaker in the presentation. Post presentation evaluations were obtained and the actual costs of the entire program have been determined. As a group utilizing telephones as a way of life, members of the AAPCC have an opportunity to lead the way in validating and verifying the effectiveness and potential cost savings of telephone conferences.

Education, Medical, Continuing↗
PubMed1982

Interactions of lectins with CHO cell surface membranes. I. Competition studies indicate concanavalin a and WGA bind to discrete populations of sites.

The binding of radioiodinated lectins to the CHO cell surface was measured for the following affinity purified plant agglutinins; concanavalin A, wheat germ agglutinin, Ricinus agglutinins (I, II) pea agglutinin, peanut agglutinin, and Bandeiria simpliciafolia agglutinin (BSLI). The number of binding sites at saturation ranged from 6 x 10(5) for BSL I to 5 x 10(7) for pea and Ricinus. Affinity constants calculated by the Steck-Wallach procedure ranged form 2 x 10(5) m(-1) for pea lectin to 4.5 x 10(5) M(-1) L for peanut lectin. Competition studies between homologous and heterologous radiolabeled and unlabeled lectins indicated that homologous unlabeled lectin could fully block binding of radiolabeled lectin. For heterologous pairs, a variety of results were observed. Of particular interest is the finding that concanavalin A and wheat germ agglutinin mutually failed to compete for binding indicating that these two lectins bind to distinct, nonoverlapping populations of surface sites. This finding suggests that the binding sites for WGA and Con A reside, for the most part, on discrete populations of membrane molecules; this concept is further validated in a companion paper in the upcoming issue of this journal (Schwartz et al., 1982).

Animals↗
PubMed1979

Cryogenic preservation of isolated rat Islets of Langerhans: effect of cooling and warming rates.

Isolated rat Islets of Langerhans have been frozen to and stored at -196 degrees. After thawing, these islets were capable of secreting near normal levels of insulin in response to graded glucose challenge. Maximal retention of functional viability as measured by the ability of the islets to secrete insulin in response to a glucose challenge was obtained after freezing islets at a cooling rate of approximately 75 degrees per minute in the presence of 1.0 mol/1 dimethyl sulfoxol followed by warming at rates of greater than 3.5 degrees/minute. The critical freezing parameters include the time and temperature of exposure to dimethyl sulfoxide, the rate of cooling, the temperature of the post-thaw dilution from the freezing medium and the presence of serum in the dilution medium.

Animals↗
PubMedDate not supplied

Magnetic field dependence of 1/T1 of protons in tissue.

It is well established that the spin-lattice magnetic relaxation rate 1/T1 of solvent protons in homogeneous protein solutions increases dramatically as the magnetic field is reduced well below the traditional NMR range. For a 5% solution of protein of 10(5) Daltons, for example, 1/T1 increases from about 50% above the pure solvent rate at 20 MHz to five times the solvent rate at 0.01 MHz. At higher fields, the effect of protein on the relaxation rate decreases progressively toward zero. 1/T1 of solvent in erythrocyte suspension behaves similarly, indicating that extracellular water has ready access to intracellular protein. We now report analogous data for samples of various mammalian tissues: we find that the data can be accommodated within the conceptual framework developed earlier for analyzing homogeneous protein solutions. It appears that tissue water probes the macromolecular composition and structure in a tissue-specific fashion. The variation of 1/T1 with field differs for each tissue, and its magnitude at low fields varies by more than a factor of three, far more than does the water content of the tissues. The relevance to contrast in NMR imaging is discussed.

Adipose Tissue↗
PubMedDate not supplied

Studies of the normal human placental syncytiotrophoblast membrane: a combined immunological and physiochemical approach.

In view of the importance of the syncytiotrophoblast in the immunobiology of human pregnancy, the composition of this interface between fetus and mother was further studied by a combination of physicochemical and immunological approaches. Trophoblast membranes were solubilized using three classes of detergents: zwitterionic (sulfobetaine14), non-ionic (Triton X-100), and anionic (deoxycholate). Quantitative studies of protein released demonstrated the importance of dispersion of membranes into detergent, and optimum solubilization was then obtained at detergent:protein ratios of 1.3:1 for sulfobetaine, 2.5:1 for Triton X-100, and 4.4:1 for deoxycholate. Analysis of chaotrope-treated detergent-solubilized membrane components was performed by preparative isoelectric focusing followed by combined physiocochemical and immunological methods. The results revealed three major proteins which were identified as placental alkaline phosphatase, albumin, and transferrin. Certain additional low molecular weight proteins were also evident; one of these components displayed physicochemical properties similar to those of actin, but none appeared to be recognized by conventional heteroantisera raised to trophoblast membrane. These findings and the results of further immunological analysis by affinity chromatography are consistent with the concept that human trophoblast may express limited immunogenicity due in part to the presence of large amounts of absorbed maternal serum components and limited expression of fetal proteins.

Albumins↗
PubMedDate not supplied

Development of a nude mouse model of ras-mediated neoplasia using WR21 cells from a transgenic mouse salivary tumor.

A novel cell line (WR21) was derived from a salivary tumor in a male wap-ras transgenic mouse. Salivary tumors in wap-ras transgenic mice are extremely aggressive and express high levels of oncogenic ras protein from the activated, human Ha-ras transgene. WR21 cells also expressed high levels of oncogenic ras protein in vitro and in vivo. They gave rise to aggressive, highly anaplastic solid tumors when injected subcutaneously into athymic nude mice and approximately 90% of the mice had lung metastases by the fifth week of tumor growth. WR21 tumors were inhibited by cyclophosphamide, 5-fluorouracil, adriamycin, mitomycin C and actinomycin D, but not methotrexate. Our results suggest that the WR21/nude mice model will be useful for testing the efficacy of drug therapies against ras-mediated neoplasias.

Animals↗