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Biomedical subjects

J B Johnson

Publications and source records attributed to J B Johnson.

At least 55 records · Page 3Linked to original sources
PubMed1982

Stability of phenylpropanolamine hydrochloride in liquid formulations containing sugars.

Stability studies with a decongestant syrup formulation containing phenylpropanolamine hydrochloride in a sugar vehicle indicated a loss of phenylpropanolamine hydrochloride. To ascertain the biological significance of this indicated chemical loss, the degraded formulation was administered to human volunteers and the urinary excretion of phenylpropanolamine hydrochloride was determined. The excretion and chemical assay patterns were in good agreement, indicating that the sugar vehicle was both chemically and biologically incompatible with phenlypropanolamine hydrochloride. A control formulation made with phenylpropanolamine hydrochloride in a sorbitol vehicle showed good chemical stability and urinary excretion patterns. Further studies showed chemical losses with phenylpropanolamine hydrochloride in the presence of fructose, dextrose, and 5-(hydroxymethyl)-2-furaldehyde but not with levulinic acid. Possible mechanisms for the sugar-phenylpropanolamine hydrochloride interaction are discussed.

Carbohydrates↗
PubMed1981

Measurement of DNA synthesis by flow cytometry.

Cells were stained for DNA content with Hoechst 33258 combined with propidium iodide and analyzed on an epi-fluorescence flow cytometer. Scatterplots of red versus blue fluorescence of control cells showed a straight line indicating that both dyes were measuring proportional amounts of cellular DNA. Scatterplots of cells incubated with the thymidine analog bromodeoxyuridine, however, showed a displacement from the control straight line that increased with longer exposure time to bromodeoxyuridine. These results suggest that bromodeoxyuridine incorporation in DNA can be detected by flow cytometry.

Adenocarcinoma↗
PubMed1981

Theophylline magnesium salicylate, a new xanthine compound.

Interaction of 1 mole of magnesium salicylate and 2 moles of theophylline in water precipitated a crystalline compound, identified as theophylline magnesium salicylate pentahydrate from analytical and supportive physicochemical data. Similarly, barium salicylate and theophylline produced theophylline barium salicylate. No precipitates were formed with calcium salicylate or strontium salicylate under the same conditions. Theophylline magnesium salicylate is not a mixture of components and differs in composition from the known theophylline calcium salicylate dihydrate. Unlike the latter compound, it is not alkaline.

Animals↗
PubMed1981

Tumorigenicity of continuous monkey cell lines in in vivo and in vitro systems.

One of the major considerations on the acceptability of a cell substrate for vaccine production concerns the potential malignancy of those cells. Consequently, we tested a variety of continuous monkey cell lines for tumorigenicity in the immunosuppressed newborn rat and immunosuppressed nonhuman primate and in the chick embryonic skin organ culture. Two positive control tumor cell lines produced progressive tumors in both in vivo systems as well as occasional metastases in the rat. The continuous monkey cell lines did not produce progressively growing tumors in the two in vivo models. However, LLC-MK2, produced occasional microscopic tumors in the nonhuman primate and newborn rat as well as lung metastases in the newborn rat test. In the organ culture assay LLC-MK2 demonstrated proliferative and invasive characteristics similar to the positive tumor lines whereas three other monkey lines were similar to secondary monkey kidney cells.

Animals↗
PubMed1979

Kinetics and cell killing in dividing and nondividing leukemic cells in vitro and in vivo by natural splenic cytotoxic factor.

Ultrafiltered splenic extracts (30,000-50,000 daltons) were specifically cytotoxic in crowded cultures of murine leukemic lymphoblasts but were only inhibitory toward normal lymphocytes or sparse cultures of leukemic cells. This expression of cytotoxicity was quantitated by (i) vital dye exclusion, (ii) cytochemical metods, and (iii) the increased survival time of mice injected with L-1210 leukemic cells incubated in vitro with splenic extract. Selective cytotoxicity of splenic extract was not due to medium depletion or to complement-mediated cytolysis and could not be replicated using similar extracts of other lymphoid and nonlymphoid tissues. The selective effect of splenic extract on leukemic cells was characterized by the progressive shedding of cytochemically demonstrable RNA and the corresponding inhibition of 3H-uridine and 3H-thymidine incorporation. The comparison of progressive and gradual expression of cytotoxicity by splenic extract with the S phase specific inhibitor cytosine arabinoside suggests that the former is cytotoxic against leukemic cells predominantly in the G1 phase of the cell cycle.

Animals↗
PubMed1979

Cytochemical and ultrastructural alteration of leukemic cells by a naturally cytotoxic factor from spleen.

Experiments were carried out to delineate the differences in cytocidal modality of natural splenic cytotoxic factor (30,000-50,000 daltons) and cyto-A against normal and human leukemic lymphocytes in vitro. It was found that the differences in the cytocidal action effected by cyto-A and splenic isolate were as follows: (1) the killing effect of cyto-A against leukemic cells was very rapid in contrast to the slowly acting spleen factor as evaluated by cytochemical and ultrastructural studies; (2) spleen factor was not cytotoxic against normal lymphocytes in contrast to the indiscriminatory cytotoxic cyto-A.

Cell Transformation, Neoplastic↗
PubMed1979

Stress reactions of various judging groups to the child dental patient.

Dental personnel representing various levels of clinical experience and education in pedodontics were shown slides of potentially stressing situations within the field of pedodontics. Stress was identified through voice analysis by the Psychological Stress Evaluator (PSE-101). Clinical experience and education in pedodontics does not decrease either absolute or relative amounts of stress. Visual stimuli are capable of eliciting a stressful response. Trained raters can interpret voice prints with a satisfactory degree of inter-rater reliability. The PSE-101 is a valid indicator of stress.

Acoustics↗
PubMed1978

Chick embryonic skin as a rapid organ culture assay for cellular neoplasia.

We used chick embryonic skin (CES) in organ culture to assess the neoplastic potential of a variety of cultured human and nonhuman cell lines. Cells derived from cancer tissues grew in CES and formed tumors in nude mice while cells derived from normal tissues grew in neither system. The CES proved to be more sensitive than the nude mouse when used to assay SV40 transformed human cells; each of four such lines grew in CES while only one of the four lines grew and formed tumors in nude mice. In addition, the patterns of invasion by inoculated cells can be easily studied in the CES. These results suggest that CES in organ culture offers an inexpensive, rapid, and reliable alternative to the nude mouse as a tumorigenicity test.

Animals↗
PubMed1978

Clinical evaluation of the Uni-Yeast-Tek system for rapid presumptive identification of medically important yeasts.

The results of over 400 tests for identification of clinical yeast isolates as to species using the Uni-Yeast-Tek (UYT) system in comparison with a more conventional system are reported. The conventional system utilized a total of 23 individual tests, including both fermentation and assimilation tests, whereas the UYT system included only 11 separate tests. In the initial phase of the study, coded unknown isolates were evaluated by each of two technologists using both methods independently. After this initial evaluation, the two methods were used in parallel for routine testing of yeast isolates as they were obtained from clinical specimens. A further evaluation of the UYT system was carried out by retrospectively analyzing the species reported from a clinical mycology laboratory during two separate time periods in which different approaches to yeast identification were employed. A total of 92% of the isolates tested with the UYT system were correctly reported within 72 h, 96% were correctly named after 1 week of incubation, and 97% were correctly reported after 2 weeks of incubation of UYT plates at 30 degrees C when results of the two phases of the study were analyzed together. With the conventional system, 88% of the isolates were correctly reported at 72 h, 96% at 1 week, and 98% after 2 weeks of incubation of biochemical tests. Retrospective analysis of laboratory records revealed no major changes in species reported after adoption of the UYT system for routine testing of clinical isolates. The data presented in this report suggest that the UYT system can be expected to yield rapid presumptive identification of clinical yeast isolates with reasonable confidence when certain minor limitations that are discussed in the text are taken into account.

Evaluation Studies as Topic↗