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Biomedical subjects

T S Johnson

Publications and source records attributed to T S Johnson.

At least 73 records · Page 4Linked to original sources
PubMed1980

Correlation of the growth of Chinese hamster V279-17lb multicellular spheroids with cytokinetic parameters.

The volumes of Chinese hamster V279-17lb multicellular spheroids grown in spinner culture were measured and correlated to DNA distribution and cell volume distribution information. Spheroid growth curves were obtained over a 21-day period using both electronic cell volume measurements and microscope micrometer sizing. The spheroids were collected from the aperture tube after electronic sizing, and single cell suspensions were prepared via trypsinization. Saline-washed cells were then stained with mithramycin and analyzed as unfixed or ethanol-fixed cells for both cell volume and DNA fluorescence measurements. Spheroid growth was determined to have an initial 8- to 9-day rapid growth phase, and a slow phase from 10 to 21 days. The single cell volume distributions of cells obtained from spheroids were dependent on spheroid volume and the relative proportions of small volume noncycling cells to large volume cycling cells comprising the spheroids were also dependent on spheroid volume. DNA distribution data and dual parameter DNA distribution cell volume contour patterns obtained for single cells dissociated from spheroids were closely related to the measured spheroid volume and revealed that the fraction of small, hypoxic G0-like cells was greatest in old, large spheroids.

Animals↗
PubMed1980

Flow cytometric applications to tumour biology: prospects and pitfalls.

A brief review of cytometry instrumentation and its potential applications in tumour biology is presented using our recent data. DNA distribution measurements of cells from spontaneous dog tumours and cultured cells after exposure to X-rays, alpha particles or adriamycin are shown. The data show that DNA fluorescence measurments have application in the study of cell kinetics after either radiation or drug treatment. Extensive and careful experimentation is needed, however, to utilize the sophisticated developments in flow cytometry instrumentation.

Animals↗
PubMed1979

A closed lung system study of inert gas absorption.

The demonstration that the rate of rise of the alveolar fraction of nitrous oxide is enhanced when the inspired N2O concentration is high is termed the "concentration effect." A similar effect on a second gas has been termed the "second gas effect". These effects have been observed in open systems and attributed to differential changes between inspired and expired ventilation. The purpose of this investigation is to study these effects in a closed system. A breath-holding maneuver was utilized with a high and a low N2O concentration in argon and oxygen. The results indicate that breath holding with a high N2O concentration "concentrates" both the alveolar fraction of N2O and argon. These results are attributable to alveolar volume shrinkage as a consequence of the large absorption of N2O by the pulmonary blood. A mathematical model verifies this interpretation and suggests that volume shrinkage can be important in breath-holding maneuvers designed for noninvasive measurement of cardiac output and lung tissue volume.

Argon↗
PubMed1978

Improvement of platelet survival time with oxygen in patients with chronic obstructive airway disease.

Platelet survival time has been found to be shortened in hypoxemic patients, and these patients may have an increased risk of thromboembolism. Supplemental O2 was administered to 10 men with sever chronic obstructive airway disease and hypoxemia. Oxygen increased platelet survival time from a mean +/- SE of 1.9 +/- 0.16 to 2.5 +/- 0.21 days (P less than 0.005; normal half-time, 3.7 +/- 0.03 days); the survival half-time was increased by 0.03 days or more in 9 of these 10 men. Arterial Po2 was increased (46.0 +/- 1.1 to 60.0 +/- 1.5 mm Hg; P less than 0.001) in all men. Results suggest that hypoxemia is associated with shortened platelet survival time and that an increase in arterial Po2 is associated with an increase in platelet survival time. Although not established by this study, the increase in platelet survival time associated with supplemental O2 may decrease the risk of thromboembolism.

Blood Platelets↗
PubMed1977

Collection of a clean voided urine specimen: a comparison among spoken, written, and computer-based instructions.

In an effort to compare different methods of instructing patients, 99 women 18-25 years of age were given computer, spoken, weitten, or no instructions for the collection of a clean voided urine specimen. The group who received computer instructions was the most uniform in its performance (P less than 0.002, F-test) and reported the fewest procedural problems (P less than 0.02, Fisher test). In addition, this group had fewer contaminating bacteria than the group who received written instructions (P less than 0.03 , Mann-Whitney test). The group who received no instructions had more bacteria (P less than 0.0001, Mann-Whitney test) than any of the other groups. The effectiveness of the computer instruction was probably related to numerous attributes, including the individualized quality of the dialogue, self-pacing, self-testing, and privacy.

Adolescent↗
PubMed1975

Immunoprophylaxis and cytotoxic effector cells against EL 4 leukemia induced in syngeneic C57BL/6J mice by use of irradiated EL 4 cells.

Tumor-specific immunoprophylaxis was achieved in C57BL/6J mice against EL 4 leukosis cell challenge by sensitization of the syngeneic host with multiple ip injections of irradiated EL 4 cells. A minimal radiation dose was used to replication-block EL 4 cells before inoculation, as defined by dose-response analysis of irradiated EL 4 cells. Multiple ip injections of irradiated EL 4 cells stimulated development of significant, yet relatively low, levels of cytotoxic lymphoid activity (CLA) in lymphoid cells of the peritoneal exudate as measured by in vitro 51Cr-release cytotoxicity assays. The specific temporal and frequency dependencies of the inoculation regimen for achieving immunoprophylaxis indicated that, in addition to CLA, other, short-lived, immune processes were important in the tumor rejection. These observations showed the capacity of the C57BL/6J host for tumor-specific immune recognition and rejection of the syngeneic EL 4 leukemia. The tumor rejection could be elicited solely by inoculations of irradiated EL 4 cells and did not require exogenous amplifiers, such as immunoadjuvants, chemical modifiers, and/or allogeneic immune information transfer.

Animals↗
PubMed1975

Low-megavoltage electron-beam therapy of head and facial skin cancer using a versatile polystyrene collimator system.

Twenty patients with multiple or recurrent superficial head and facial cancer were treated with low-megavoltage electron-beam therapy, using a readily adaptable polystyrene shield assembly with interchangeable collimators. Patient set-up times were reduced, treatment was simplified, and flexibility of therapy was achieved. Therapeutic response was excellent even in patients with extensive primary or recurrent skin cancer requiring large-field irradiation.

Aged↗
PubMedDate not supplied

Reliability of length measurements in full-term neonates.

OBJECTIVE: To describe and compare the intra- and interexaminer reliability of four techniques for measuring length in full-term newborns and to determine whether the different techniques yield significantly different measurements. DESIGN: A descriptive study, describing the intra- and interexaminer reliability of four length measurement techniques: crown-heel, supine, paper barrier, and Neo-infantometer. The nurses were blind to their own and to the other nurse's measurements. The order of the nurses and the order in which the measurements were obtained was randomized. SETTING: Mothers' rooms in a university hospital. PARTICIPANTS: Thirty-two healthy full-term newborns. INTERVENTIONS: Length measurements using four different length techniques were obtained twice each by two experienced neonatal nurses. MAIN OUTCOME MEASURES: To measure the intra- and interexaminer reliability, the following statistics were calculated: mean absolute differences, standard deviations, technical error of measurement; percentage less than .5 and 1.0 cm, and percentage of error. RESULTS: Intra- and interexaminer differences were significantly larger when examiners used the crown-heel measurement technique. Although the intra- and interexaminer reliability of length measurements obtained with the supine, paper barrier, and Neo-infantometer techniques did not differ significantly, the amount of error in these measurements was large. CONCLUSIONS: Measurements obtained using the crown-heel technique are significantly less reliable than measurements obtained using the supine, paper barrier, or Neo-infantometer techniques.

Anthropometry↗
PubMedDate not supplied

A home visit program for breastfeeding education and support.

A home visit program for breastfeeding education and intervention was developed to provide support for mothers and infants at risk for breastfeeding failure. This program was developed to supplement the Early Discharge Program for mothers and newborns who were discharged within 24 hours of delivery. A breastfeeding assessment tool was developed for use in the hospital and during the early discharge home visit. Home visits are provided by a registered nurse with mother-infant assessment skills and competence to provide breastfeeding education, problem management, emotional support, and referrals to lactation consultants or physicians as needed. The response from patients and physicians has been positive. As the demand for services grew, the program was modified to include other mothers and infants (e.g., those delivering via cesarean and high-risk, preterm, and borderline preterm infants in need of breastfeeding support). The readmission rate for breastfeeding infants who receive a home visit is lower than for infants who do not receive a home visit. Patient satisfaction surveys have been positive.

Breast Feeding↗