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Biomedical subjects

R D Fletcher

Publications and source records attributed to R D Fletcher.

At least 127 records · Page 7Linked to original sources
PubMed1977

Measurement of the adhesive strength of a gingival cell line to agar.

A new technique is described for measuring the adhesive strength of a gingival cell line to an agar substratum by the modification of the original "blister" test for adhesives. A cell monolayer was developed on a Petri dish with a hole in the center of the growing surface, overlayed with agar, and the system pressurized to debond the cells from the agar surface. Pressure changes were measured by a capacitance pressure transducer the output of which was measured by a strip-chart recorder. The modulus (E) of the agar overlay was determined and used in the calculation of the adhesive-bond strength (gammaalpha). The gammaalpha yield for the gingival cell line (cell-agar debond) was 48.8 ergs per cm2, and for the control (no cells) (agar-polystyrene debond) was 30.0 ergs per cm2.

Agar↗
PubMed1977

Pericarditis mimicking tricuspid valvular disease.

A patient with rheumatoid disease initially had the physical findings of isolated tricuspid stenosis. Postmortem examination demonstrated adhesive pericarditis with localized hemopericardium which compressed the atrioventricular groove in the area of the tricuspid valve. Historical, physical, electrocardiographic, and cardiac catheterization features which suggested the diagnosis are discussed.

Arthritis, Rheumatoid↗
PubMed1976

Effects of pentadecan-2-one on the growth of cells in culture.

The effect of inclusion of trace amounts of pentadecan-2-one in the incubation medium on the growth of HeLa Cells was evaluated by measuring viable cell counts (cells excluding trypan blue) and incorporation of [14C] leucine into acid precipitable protein. Evidence is presented to show that exposure of the cells to trace amounts of the methyl ketone, 36mug/ml, effectively inhibits cell growth. This inhibition is relieved by simultaneously incubating the cells with a long chain primary alcohol, hexadecan-1- o1, but not with the secondary alcohol, pentadecan-2-o1. The observation that the ethyl ketone, hexadecan-3-one, also inhibits cell growth but at higher concentrations than that observed with pentadecan-2-one and that pentadecan-2-o1 at similar concentrations has no effect on cell growth indicates that, for optimal effect, the keto function must be at the 2-position. Inhibition of cell growth by pentadecan-2-one is not unique to HeLa cells, as suggested by the inhibitory effects of this lipid type on the growth of other malignant cell lines of human origin.

Alkanes↗
PubMed1976

Susceptibility of Haemophilus influenza to ampicillin as determined by use of a modified, one-minute beta-lactamase test.

Fifty-seven cultures of Haemophilus influenzae were tested for production of beta-lactamase by use of a modified, 1-min test. Only the 24 cultures that were ampicillin resistant, whether type b or not, yielded positive results for the enzyme; all ampicillin-susceptible isolates were uniformly negative. The beta-lactamase procedure is simple to perform and requires only commonly available reagents.

Ampicillin↗
PubMed1976

Prolonged His-Q interval in chronic bifascicular block. Relation to impending complete heart block.

Although prolonged infra-His conduction time in bifascicular block is suspected of denoting trifascicular disease, adquate documentation is lacking concerning the correlation between lengthened His-Q interval (H-Q) and the risk of development of complete heart block (CHB). H-Q in conducted sinus beats in patients with bifascicular block associated with Mobitz II or intermittent CHB represents the approximation of maximal H-Q prolongation prior to onset of trifascicular block. To assess this relationship between prolongation of H-Q and trifascicular block, His bundle electrocardiography (HBE) was performed in 50 patients with chronic bifascicular block exhibiting Mobitz II block or transient CHB. Mobitz II or episodic CHB was shown in all patients: within two days prior to HBE in 45/50 patients; in 39/50 patients during HBE; and following HBE in five patients. In 49/50 patients H-Q was prolonged (greater than 55 msec) and in 47 this interval was substantially lengthened (65 msec or greater). Since marked H-Q prolongation in conducted sinus beats was documented in nearly all patients with bifascicular block associated with intermittent complete trifascicular block, we conclude that a considerably lengthened H-Q interval in bifascicular block is not only a usual prerequisite but strong evidence, for impending complete heart block.

Adult↗