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Biomedical subjects

C E Bennett

Publications and source records attributed to C E Bennett.

At least 37 records · Page 2Linked to original sources
PubMed1981

Studies on the toxicity and binding kinetics of abrin in normal and Epstein Barr virus-transformed lymphocyte culture-I: experimental results - 3.

The effects of treatment with varying doses of abrin, a D-galactose binding lectin, on DNA and protein synthesis of normal and Epstein Barr virus-transformed lymphocytes have been investigated. Using data on EBV-transformed lymphocyte cell density as a function of time and dose of abrin, one can demonstrate that the mean number of sites bound/EBV-lymphocyte needed to exert a biological influence upon the cell DNA synthesis lies between 59,264 and 370,000 sites/cell. Using a simple packing model, one can demonstrate that a theoretical estimate places the number of binding sites between 57,600 and 360,000 sites/cells.

Abrin↗
PubMed1981

On the dynamics of abrin binding to receptor sites in normal and Epstein Barr Virus transformed lymphocyte cell cultures.

The effects of treatment with varying doses of abrin, a D-galactose binding lectin, on DNA an protein synthesis of normal and Epstein Barr Virus transformed lymphocytes has been investigated. Activation, stimulation, and relative toxicity factor indices are studied, as well as possible relationships between DNA and protein synthesis rates, as measured by simultaneous tritiated thymidine (3H-TdR) and 14C-leucine uptake. Studies of the two new indices, the metabolic self and cross coupling indices lead to the prediction that there are three morphologically distinct subpopulations of EBV-transformed lymphocytes with different abrin receptor site concentrations. This prediction is supported by SEM morphological differences. Using data on EBV-transformed lymphocyte cell density as a function of time and dose of abrin, one can demonstrate that the mean number of receptors bound-EBV-lymphocyte needed to exert a biological influence lies in the interval 59,264 receptors/cell to 370.040 receptors/cell. Using a simple packing model, one can demonstrate that a theoretical estimate places the number of binding sites between 57,600 receptors/cell and 360,000 receptors/cell.

Abrin↗
PubMed1980

Trace metal levels in commercially prepared tissue culture media.

Four trace elements, lead, copper, tin and zinc, in addition to certain electrolytes, were measured in 11 commercially prepared tissue culture media. Glass media bottles and plastic tissue culture dishes and flasks were treated with a HCl acid solution to determine the amounts of trace metals leached from their surfaces. Zinc, lead and copper were detected in all media. Tin was detected only in RPMI Medium 1640, fetal bovine serum, minimum essential medium and penicillin-streptomycin. It is possible that a major cause of variability in tissue culture experimental results may be due to effects on growth caused by fluctuation in trace element contamination from batch to batch. Variability in establishing primary cultures of corneal endothelial cells was traced to high lead levels in commercially prepared tissue culture media. A strong case is made for continued diligent efforts to expand analytical horizons and our definition of substances in culture media.

Copper↗
PubMed1979

Corneal endothelium: a modified method for cultivation.

A modified method for establishing cultures of rabbit corneal cells is described. The new technique utilized a Lucite disc in combination with a Tygon ring for growth of pure cell cultures and was compared with an explant method for growing cells. Each method provided adequate cell cultures for biochemical or ultrastructure studies of rabbit corneal cells, but the ring and disc method described here allowed the isolation of specific cell types without the interference of stromal cell contamination.

Animals↗
PubMed1979

Redundant nutritive tubes in insect ovarioles: the fate of an extensive microtubule transport system.

The developing oocytes in the ovarioles of hemipteran insects receive materials from nutritive cells by way of channels known as nutritive tubes. The tubes contain an extensive system of microtubules which are thought to be involved in the transport between the two cell types. At the onset of vitellogenesis the connection is discontinued. Redundant nutritive tubes have been identified, compared with functional tubes, and their fate discussed.

Animals↗
PubMed1979

Relationship between virus neutralization and serum protection bioassays for IgG and IgM antibodies to foot-and-mouth disease virus.

The time interval between administering the serum and the virus was found to influence the results of the in vivo mouse protection test for foot-and-mouth disease antibodies. In particular, for both IgG and IgM antibodies to strain A12 virus, the mouse protection index increased from zero to a maximum at about 6 h and remained high for at least five days. Variations in the antiserum concentration, on a log scale, had a proportional effect on the mouse protection index, if between 1 and 3. The constant of proportionality was unity for IgM and 2 for IgG antibody. Comparison with in vitro neutralization tests revealed essentially parallel neutralization curves. The lower serum titre in the protection test, if computed for less than 10(3) LD50/dose, was accounted for by the simple dilution of the inoculated serum into the volume of the mouse. Consequently, in the low titre range, the same virus-antibody reaction and its effect are operable in each of the two tests. Analysis of literature data in which both the in vivo protection test and the in vitro neutralization test results were available on the same sera showed consistency with the above conclusions for both cattle and swine sera. The protection test had a highly atypical survival pattern occurring at antibody concentrations expected to neutralize more than 10(3) LD50/dose. The resulting in vivo dampening effect on virus titre is postulated to be caused by the excess antibody of the passive immunity test interfering with the spread of infection. The effect is analogous to an anomaly caused by not removing the inoculum in quantal tissue culture assays and it prevents quantification of antibody levels in strong sera.

Animals↗
PubMed1978

The identification of soluble adult antigen on the tegumental surface of juvenile Fasciola hepatica.

An antiserum was raised in rabbits against a soluble extract of fresh homogenized adult Fasciola hepatica of rat origin and was then absorbed with rat and mouse tissue antigens. This antiserum reacted specifically with the surface coat of adult flukes, of both rat and mouse origin, by indirect immunofluorescence to show the detail of surface spines. When tested against juvenile stages recovered from mice the reaction was positive with all but the earliest hepatic parenchyma stages. No reaction was present on the tegumental surface of newly excysted juveniles or stages 1 or 2 days post-infection (p.i.) whether recovered from the peritoneal cavity or the hepatic parenchyma.

Animals↗
PubMed1977

Bacterial gram staining by conventional and strip methods.

Conventional gram staining was compared with a method which uses dye impregnated paper strips for staining. The paper strip technique was judged accurate and reproducible and is recommended for use in the small laboratory and hospital ward.

Bacteriological Techniques↗
PubMed1976

Stimulation of thymidine uptake and cell proliferation in mouse embryo fibroblasts by conditioned medium from mammary cells in culture.

Undialyzed conditioned medium from several cell culture sources did not stimulate thymidine incorporation or cell overgrowth in quiescent, density-inhibited mouse embryo fibroblast cells. However, dialyzed conditioned medium (DCM) from clonal mouse mammary cell lines MCG-V14, MCG-T14, MCG-T10; HeLa cells; primary mouse adenocarcinoma cells; and BALB/c normal mouse mammary epithelial cells promoted growth in quiescent fibroblasts. The amount of growth-promoting activity produced per cell varied from 24% (HeLa) to 213% (MCG-V14) of the activity produced by primary tumor cells. The production of growth-promoting activity was not unique to tumor-derived cells or cells of high tumorigenicity. The amount of growth-promoting activity produced per cell in the active cultures was not correlated with any of the following: tumorigenicity, growth rat, cell density achieved at saturation, cell type, or species of cell origin. It is concluded that transformed and non-transformed cells of diverse origin, cell type, and tumorigenicity can produce growth factors in culture. The growth-promoting potential of the active media from primary tumor cultures accumulated with time of contact with cells and was too great to be accounted for entirely by the removal of low-molecular-weight inhibitors by dialysis. The results are consistent with the hypothesis that conditioned medium from the active cultures contained a dialyzable, growth-promoting activity. Different cell lines exhibited differential sensitivity to tumor cell DCM and fetal bovine serum. Furthermore, quiescent fibroblasts were stimulated by primary tumor cell DCM in the presence of saturating concentrations of fetal bovine serum. These observations support the notion that the active growth-promoting principle in primary tumor cell DCM may not be a serum factor(s).

Adenocarcinoma↗
PubMed1975

Surface features, sensory structures, and movement of the newly excysted juvenile Fasciola hepatica L.

Three types of presumed sensory endings were distinguished by scanning electron microscopy: a ciliated type, a domed type, and a pit. The ciliated and domed type were also serially sectioned for transmission electron microscopy. Six of the pit type were observed, a group of 3 on each side of the oral sucker. The ciliated type were found only among the tegumental spines, and on the anterior ventrolateral surfaces except for an anterodorsal pair. The domed type resembled the ciliated type in that it had a ciliary basal body and rootlet but it lacked a cilium. It was found only in the tegument above the suckers where it probably serves as a pressure or contact receptor. Movement in vitro occurred by alternate attachment and release of the suckers with a vermiform peristalsis and the rings of spines between the suckers were considered to aid this movement in vivo.

Animals↗
PubMed1975

Scanning electron microscopy of Fasciola hepatica L. during growth and maturation in the mouse.

Throughout the entire life of the fluke the spines anterior to the ventral sucker are arranged in approximately 60 rings each of 60 to 70 spines. The spines on the posterior body are scattered without any pattern of rings and by 1 week post infection (p.i.) their numbers have doubled (from 3,000 on the newly excysted juvenile) to 6,000 and by 3 weeks p.i. their numbers have multiplied by 8 to 24,000. Just prior to entry into the bile ducts, between 2 and 3 weeks p.i., all spines, anterior and posterior, have metamorphosed from single pointed to multipointed forms by division at the spine tips. Spines on the anterior body of mature flukes recovered from the bile ducts of mice 26 weeks p.i. have between 10 and 15 points whereas those on the posterior body have up to 30 points. The tegument forms a rectangular pattern of plateaux and valleys around each spine on the posterior body of mature flukes but this pattern is not present on the anterior body.

Animals↗