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Biomedical subjects

M L Lewis

Publications and source records attributed to M L Lewis.

At least 73 records · Page 4Linked to original sources
PubMed1988

Correlation of bronchoalveolar lavage cell populations with clinical severity of Pneumocystis carinii pneumonia.

We correlated bronchoalveolar lavage (BAL) cell populations with clinical course and outcome in 19 patients with Pneumocystis carinii pneumonia and acquired immunodeficiency syndrome. Twelve patients demonstrated an elevated (greater than or equal to 5 percent) BAL combined neutrophil and eosinophil count, which correlated with the magnitude of the alveolar-arterial PO2 gradient. Patients with elevated BAL granulocytes also had significantly higher serum lactate dehydrogenase levels. Three of the four patients who died had the highest percentage of neutrophil counts observed in lavage fluid. Although no patient was thought to have a concurrent bacterial infection, potential pathogens were cultured from the sputum of patients with the most elevated neutrophil counts. Whether BAL granulocytes reflect an inflammatory process analogous to the adult respiratory distress syndrome or signify concomitant bacterial infection remains to be determined. We conclude that BAL granulocytes are associated with more severe respiratory compromise in patients with Pneumocystis carinii pneumonia.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Elevated lactate dehydrogenase values in patients with Pneumocystis carinii pneumonia.

We investigated the source of elevated serum lactate dehydrogenase (LDH) levels in seven patients with Pneumocystis carinii pneumonia (PCP) by analyzing blood and bronchoalveolar lavage (BAL) albumin (ALB) and LDH, with isoenzyme fractionation. Four patients with non-PCP lung disease served as control subjects. In PCP patients, BAL LDH was sixfold higher, and BAL ALB, fourfold higher than in the non-PCP patients. The increased LDH/ALB in BAL as compared to serum, in addition to a BAL isoenzyme pattern characteristic of lung, suggest that BAL LDH arises from a pulmonary source. We postulate that the high correlation observed between BAL and serum LDH (r = 0.93, p less than 0.001) reflects backflow of pulmonary-derived LDH into the blood through an alveolocapillary membrane (ACM) compromised by PCP. Furthermore, a comparison of BAL LDH/ALB for each isoenzyme with the same serum ratio showed less backflow for the cationic isoenzymes. The ACM appears to sieve proteins on an electrical basis which may account for the LDH isomorphic pattern observed in the serum of PCP patients.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Continuous flow electrophoretic separation of proteins and cells from mammalian tissues.

A new continuous flow electrophoretic separator for cells and macromolecules was built and tested in laboratory experiments and in the microgravity environment of space flight. Buffer flows upward in a 120-cm long flow chamber, which is 6 cm wide X 1.5 mm thick in the laboratory version and 16 cm wide X 3.0 mm thick in the microgravity version. Electrophoretic subpopulations are collected in 197 fractions spanning 16 cm at the upper end of the chamber. The electrode buffer is recirculated through front and back cooling chambers, which are also electrode chambers. Ovalbumin and rat serum albumin were used as test proteins in resolution and throughout tests; resolution of these two proteins at 25% total w/v concentration in microgravity was the same as that found at 0.2% w/v concentration in the laboratory. Band spreading caused by Poiseuille flow and conductance gaps was evaluated using polystyrene microspheres in microgravity, and these phenomena were quantitatively the same in microgravity as in the laboratory. Rat anterior pituitary cells were separated into subpopulations enriched with cells that secrete specific hormones; growth-hormone-secreting cells were found to have high electrophoretic mobility, whereas prolactin-secreting cells were found to have low electrophoretic mobility. Cultured human embryonic kidney cells were separated into several electrophoretic subfractions that produced different plasminogen activators; a medium-high-mobility subpopulation and a medium-low-mobility subpopulation each produced a different molecular form of urokinase, whereas a high- and an intermediate-mobility subpopulation produced tissue plasminogen activator. Canine pancreatic islets of Langerhans cells were separated into subpopulations, which, after reaggregation into pseudoislets, were found to be enriched with cells that secrete specific hormones; insulin-secreting beta cells were found in lowest mobility fractions, whereas glucagon-secreting alpha cells were found in the highest mobility fractions. Results of particle electrophoresis experiments were comparable in microgravity and in the laboratory, since cell densities that overloaded the carrier buffer (resulting in zone sedimentation) were avoided, and a 500-fold increase in protein throughput was achieved without compromising resolution in microgravity.

Animals↗
PubMed1987

Obliterative otosclerosis.

A total of 2,985 stapedectomies were done during the 25-year period 1959 to 1984 in a busy urban otologic practice. One hundred twenty-three of these cases were found to have obliterative otosclerosis which resulted in a drill-out stapedectomy. Postoperatively, a minimum of 2 years follow-up yielded 98 of the original 123 drill-out cases constituting the study group. Several parameters will be evaluated: 1. Initial hearing gain (measured 3 months after surgery), 2. long-term hearing results (measured 2 years and beyond), 3. additional sensorineural hearing loss, and 4. probability of bilateral obliterative disease.

Follow-Up Studies↗
PubMed1986

Electrophoretic separation and analysis of living cells from solid tissues by several methods. Human embryonic kidney cell cultures as a model.

Preparative electrophoresis of living cells has been considered for some time as a potential tool for isolating, from heterogeneous mixtures, subpopulations of cells according to function. Such a purification depends upon the retention of electrophoretic heterogeneity and the retention of function. Human embryonic kidney cells that had been in monolayer culture for 1-5 subcultivations were resuspended by treatment with trypsin and/or EDTA and suspended in a variety of electrophoresis buffers, ranging in ionic strength from 0.0015 to 0.15 M. Analytical electrophoresis with a Zeiss Cytopherometer or Pen Kem 3000 automated light-scattering electrophoretic analyzer indicated that electrophoretic heterogeneity was retained under the full range of conditions tested. Preparative electrophoresis by three methods--in a density gradient, with continuous flow, and in microgravity--indicated that electrophoretic heterogeneity coincided with functional heterogeneity; for example, some electrophoretically isolated subpopulations produced increased levels of urokinase while others produced increased level of tissue plasminogen activator.

Buffers↗
PubMed1986

Prenatal diagnosis of hereditary red cell membrane defect.

The red cells of a severely anaemic 2-year-old child of a white British family showed high haemolytic fragility with poikilocytosis. The cells showed markedly impaired thermal stability. The mother was phenotypically normal, but the father's red cells showed mild elliptocytosis. The spectrin from the latter, extracted at low temperature, was 30% dimeric (cf. 5-10% in normals). Tryptic digests of the spectrin from both father and daughter showed a reduction in the fragment of 80,000 molecular weight, derived from the terminus of the alpha-chain, and the elevation of a fragment of molecular weight 46,000, as well as one of 53,000. These characteristics and the autosomal recessive inheritance lead to a diagnosis of type II hereditary pyropoikilocytosis, so far reported only in two black American families (Lawler et al, 1983). The spectrin from the father was examined with respect to thermal conformational stability, and was found to be normal. The spectrin from the cells of the daughter gave evidence of the presence of oxidative (disulphide) cross-links, as well as of extensive noncovalent aggregation. Blood was obtained from the umbilical cord vein of the 19-week fetus of the pregnant mother: 250 microliters of blood was used for preparation of red cell membranes for SDS-gel electrophoresis and for extraction of spectrin. Analysis of the spectrin by gel electrophoresis in the native state revealed that the proportion of dimer was within the normal range, and the fetus therefore did not possess the hereditary pyropoikilocytosis phenotype. It is suggested that the procedures described could be generally applied to the prenatal identification of phenotypes associated with severe haemolytic anaemias.

Anemia, Hemolytic, Congenital↗
PubMed1985

The effect of previous experience on preference of approach for effective counseling.

Students in a general psychology class viewed four videotapes of initial vocational-educational and initial personal concern counseling sessions. The sessions were presented from a client-centered approach and from a behavioral approach, and employed the same client and counselor. After viewing the tapes, the students were asked to indicate which approach they thought would be more effective in helping a client. Results showed that students who had previously experienced counseling preferred a behavioral approach for both the vocational-educational concern and the personal concern. Students with no experience of counseling did not exhibit a preference.

Adult↗
PubMed1984

Problems in the bioassay of products from cultured HEK cells: plasminogen activator.

For research and commercial purposes, the production of materials from cultured cells is progressively becoming routine. Measuring products in cell culture medium, however, is not always straight-forward even when the most appropriate product assays are utilized. A researcher interested in a particular cell product does not intend to spend time developing or refining existing assays. Instead, he would prefer using techniques and standards reported in the literature. Evaluations of enzyme activity using purified standards or control products may inadvertently lead to the assumption that the same procedures will give reproducible results when cell culture medium is assayed for the product. This report describes the selection of commercially available lots of human embryonic kidney cells and the activity of the plasminogen activator (PA) produced by these cells. PA activity was measured by the fibrin plate assay. The problems of comparing activity in conditioned culture medium with that of purified standard preparations are presented. Factors contributing to non-linearity in dose response curves, inconsistencies in activity in replicate flask cultures, and variations in repeated assays after sample storage are considered. Sample handling procedures and alternate assay systems are discussed.

Animals↗
PubMed1984

Bioprocessing in space: human cells attach to beads in microgravity.

Attachment to a substrate and survival of human embryonic kidney (HEK) cells have been tested in an incubator installed in the flight-deck of the Space Shuttle 'Challenger' during its eighth mission. HEK cells are producing the enzyme urokinase and are presently investigated as candidates for electrophoretic separation in an apparatus developed and manufactured by McDonnell Douglas. Attachment of HEK cells to a substrate is mandatory for survival and production of urokinase after electrophoretic separation. Analysis of the samples shows that cells adhere, spread and survive in microgravity (< 10(-3) x g) conditions as well as the ground controls at 1 x g. This result represents an important step towards further bioprocessing in space.

Biotechnology↗
PubMed1984

Electrophoretic separation of kidney and pituitary cells on STS-8.

A Continuous Flow Electrophoresis System (CFES) was used on Space Shuttle flight STS-8 to separate specific secretory cells from suspensions of cultured primary human embryonic kidney cells and rat pituitary cells. The objectives were to isolate the subfractions of kidney cells that produce the largest amounts of urokinase (plasminogen activator), and to isolate the subfractions of rat pituitary cells that secrete growth hormone, prolactin, and other hormones. Kidney cells were separated into more than 32 fractions in each of two electrophoretic runs. Electrophoretic mobility distributions in flight experiments were spread more than the ground controls. Multiple assay methods confirmed that all cultured kidney cell fractions produced some urokinase, and five to six fractions produced significantly more urokinase than the other fractions. Several fractions also produced tissue plasminogen activator. The pituitary cells were separated into 48 fractions in each of the two electrophoretic runs, and the amounts of growth hormone (GH) and prolactin (PRL) released into the medium for each cell fraction were determined. Cell fractions were grouped into eight mobility classes and immunocytochemically assayed for the presence of GH, PRL, ACTH, LH, TSH, and FSH. The patterns of hormone distribution indicate that the specialized cells producing GH and PRL are isolatable due to the differences in electrophoretic mobilities.

Animals↗
PubMed1984

Properties of electrophoretic fractions of human embryonic kidney cells separated on Space Shuttle flight STS-8.

Suspensions of cultured primary human embryonic kidney cells were subjected to continuous flow electrophoresis on Space Shuttle flight STS-8. The objectives of the experiments were to obtain electrophoretically separated fractions of the original cell populations and to test these fractions for the amount and kind of urokinase (a kidney plasminogen activator that is used medically for digesting blood clots), the morphologies of cells in the individual fractions, and their cellular electrophoretic mobilities after separation and subsequent proliferation. Individual fractions were successfully cultured after return from orbit, and they were found to differ substantially from one another and from the starting sample with respect to all of these properties.

Cell Line↗
PubMed1984

Retinal detachment following the acute retinal necrosis syndrome.

Twenty-six patients with the acute retinal necrosis involving 32 eyes have been followed at the Bascom Palmer Eye Institute. Sixteen eyes developed retinal detachment and surgical repair was attempted in thirteen. Ten eyes were successfully reattached. Vitreous surgery was necessary in ten eyes and was performed in eight of the ten successful eyes. The clinical characteristics of the retinal detachments as well as the surgical procedures and results are presented.

Acute Disease↗
PubMed1984

Spinal cord or nerve root compression in patients with malignant disease: CT evaluation.

Fifty patients with malignant disease were seen on an emergency basis because they showed clinical signs of spinal cord or nerve root compression. All were studied with high resolution computed tomography (CT) of the spine; in addition, myelography was performed on 10 of the patients. We found that 48 cases (96%) could be accurately diagnosed by CT alone. In two cases (4%) CT was inconclusive, but myelography was diagnostic; one proved to be cerebrospinal fluid seeding with nerve root involvement, and the other showed conus medullaris involvement. In the remaining eight cases studied by both techniques, correlation between CT and myelography was very good.

Adult↗
PubMed1984

Posterior fossa ependymal cyst and atlantoaxial subluxation in a patient with Down syndrome: CT findings.

A 61-year-old woman with Down syndrome presented with progressive deterioration of gait over 9 months. Cranial CT without and with intravenous administration of contrast material demonstrated a posterior fossa cyst. The cyst did not communicate with the fourth ventricle or subarachnoid spaces as proven by CT following a metrizamide ventriculogram. Surgical fenestration of the cyst into the fourth ventricle was done. In addition, a moderate atlantoaxial subluxation with 2 mm movement from extension to flexion was present, which was thought not to be clinically significant, but which might require a spinal fusion at a future time. Ependymal cells were found as a result of a biopsy of the cyst wall.

Atlanto-Axial Joint↗