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R J Jones

Publications and source records attributed to R J Jones.

At least 253 records · Page 14Linked to original sources
PubMed1966

Inoculum-dependent division lag of Bacillus cultures and its relation to an endogenous factor(s) ("schizokinen").

Lankford, C. E. (The University of Texas, Austin), James R. Walker, James B. Reeves, N. H. Nabbut, B. R. Byers, and R. J. Jones. Inoculum-dependent division lag of Bacillus cultures and its relation to an endogenous factor(s) ("schizokinen"). J. Bacteriol. 91:1070-1079. 1966.-When cells of Bacillus megaterium, grown on Brain Heart Infusion Agar, were inoculated into a chemically defined medium, they exhibited a division lag which was an inverse function of inoculum size. The addition of filtrates of cultures from the same medium eliminated the inoculum-dependent component of lag, but not an inoculum-independent residual lag of constant duration. Culture filtrate of B. subtilis var. niger not only eliminated its inoculum-dependent lag but also was required to sustain exponential division. Dose-response and "growth time" bioassays, developed to measure lag-reducing activity of filtrates, demonstrated accumulation of active filtrate factor to a "critical" concentration prior to division initiation. Addition of this concentration to cultures eliminated the inoculum-dependent lag. Accumulation of the factor ceased temporarily at onset of division, but excretion was resumed later during exponential growth. Accumulation of a lag-reducing, cell-associated factor followed a similar course. Chromatographic and bioautographic analyses of culture filtrates of B. megaterium indicated that a single substance was primarily responsible for their activity. Results of dose-response tests for reciprocal activities of filtrates of different Bacillus species and strains suggested production of different factors by some, and of different quantities of similar factors by others. It is proposed that such endogenous factors which are synthesized and accumulate to a population-dependent concentration as a requisite to initiation and maintenance of division be designated as "schizokinens."

Bacillus cereus↗
PubMedDate not supplied

Diurnal variation in the b-wave implicit time of the human electroretinogram.

Photopic electroretinograms (ERGs) elicited by light flashes were recorded for three normal human subjects who were exposed, throughout, to natural ambient light cycles over 24-h day-night periods. ERGs were recorded either with the adaptation state of the eyes maintained at the level set by the natural ambient lighting, or after 10 min dark adaptation. The amplitudes and implicit times of both the a- and b-wave components of the ERG were examined and of these, only the b-wave implicit time exhibited significant diurnal variation, such that the nighttime values were 20-40% greater than those recorded during daytime. Such diurnal variations were observed under both recording conditions and cannot, therefore, be attributed to diurnal changes in the adaptation state of the cone photoreceptors. ERGs were recorded at midday and midnight during 24-h exposure to the natural light cycle, but during the recording period, the short-term adaptation state of the eye was controlled by exposure to rod saturating background field, so that visual sensitivity was the same at both recording times. The b-wave implicit times recorded at midnight were, nonetheless, greater than those recorded at midday. This difference is not, therefore, determined by the short-term state of retinal adaptation, but reflects long-term light history. Measurements performed under 24-h continuous light exposure showed no variation in the b-wave implicit time, whereas some measurements made during extended dark adaptation provided limited evidence for implicit time changes. By controlling the wavelengths to which the eye was exposed during the daylight phase of the diurnal cycle, it was shown that the shifts in b-wave implicit time associated with the change from dark to light are triggered by the rod system, although they are most clearly observed in the cone-dominant responses to long-wavelength light. The results demonstrate a diurnal variation in the temporal responses of the post-photoreceptoral cone pathways of the human retina, which is triggered by activation of the rod photoreceptors.

Adult↗
PubMedDate not supplied

Pharmacokinetics of salicylate ester prodrugs of cyclic HPMPC in dogs.

A series of aryl ester prodrugs of cyclic HPMPC have been synthesized and their physicochemical properties, pharmacokinetics and metabolism have been evaluated. Chemical stability was dependent on the orientation of the exo-cyclic ligand; the equatorial isomers were 5.4 to 9.4 fold more reactive than the axial isomers. The oral bioavailability of cyclic HPMPC from the aryl ester prodrugs ranged from 11.2% for o-pentylphenyl cyclic HPMPC to 46.3% for butylsalicylyl cyclic HPMPC. Cyclic HPMPC was the major metabolite observed for all the salicylyl ester prodrugs. Cidofovir accounted for 2 to 12% of the total plasma AUC for butyl-, cyclohexyl- and phenethyl-salicylyl esters of cyclic HPMPC. Intact prodrug or the corresponding monosalicylyl esters of cidofovir each accounted for less than 10% of the total AUC for salicylyl ester prodrugs.

Administration, Oral↗
PubMedDate not supplied

Immunization of burned patients against Pseudomonas aeruginosa infection at Safdarjang Hospital, New Delhi.

Patients (746) aged one to 60 years admitted to Safdarjang Hospital with full skin-thickness burns over 5%-70% of their body surface were randomly allocated to a group in a controlled clinical trial in which polyvalent pseudomonas vaccine (PEV-01), antipseudomonas human immunoglobulin, pseudomonas vaccine and immunoglobulin, or no immunologic prophylaxis was administered. The mortality rate for 297 patients immunized with PEV-01 was reduced fourfold in adults and more than twofold in children as compared with that for the 263 patients who received no immunoprophylaxis. Children particularly benefited from prophylaxis with immunoglobulin; the mortality rate for children who received PEV-01 was more than twofold less than that for a control group of unimmunized children. In both children and adults, immunoprophylaxis with PEV-01 plus immunoglobulin was less effective in reducing mortality than was PEV-01 or immunoglobulin administered alone. Antibodies measured by passive hemagglutination and by passive protection tests failed to correlate with one another, but all three immunologic regimens enhanced the bactericidal capacity of whole blood against Pseudomonas aeruginosa. Klebsiella pneumoniae emerged as the dominant gram-negative bacterial species causing bacteremia in patients receiving immunoprophylaxis against P. aeruginosa.

Adolescent↗