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Biomedical subjects

A G Freeman

Publications and source records attributed to A G Freeman.

At least 37 records · Page 2Linked to original sources
PubMed1987

Effect of ultraviolet radiation on the Bacillus subtilis phages SPO2, SPP1 and phi 29 and their DNAs.

A comparative study of the effects of ultraviolet radiation on three Bacillus subtilis phages is presented. Phages phi 29, SPP1 and SPO2c12 or their DNAs were irradiated by UVC (254 nm) and quantum yields for inactivation were calculated. For each phage, the purified DNA was found to be more sensitive than the intact virus when assayed in a uvr+ host. The data imply that this is because transfecting DNA is repaired less efficiently than DNA of the intact phage; rather than because of differences in sensitivity to lesion production. Even though phi 29 has the smallest target size of the three phages, phi 29 and its DNA are the most sensitive. Phages SPO2 and SPP1 code for gene products which complement the repair system of the host. The transfecting DNA of phage SPP1 is extremely sensitive to UV damage when assayed in a uvr-host. This is attributed to the fact that in transfection SPP1 DNA must undergo recombination for productive infection to occur. The recombination process strongly interferes with the repair of damaged DNA.

Bacillus subtilis↗
PubMed1985

Transformation of human cells by DNAs ineffective in transformation of NIH 3T3 cells.

Neonatal human foreskin fibroblasts can be transformed to anchorage-independent growth by transfection with DNAs inefficient in transforming NIH 3T3 cells. Human cells transfected with DNA from GM 1312, a multiple myeloma cell line, or MOLT-4, a permanent lymphoblast line, grow without anchorage at a much higher frequency than do the parental cells and their DNAs can transform human cell recipients to anchorage-independent growth; they have extended but not indefinite life spans and are nontumorigenic. Human fibroblasts are also transformed by DNAs from two multiple myeloma lines that also transform 3T3 cells; however, restriction analysis suggests that different transforming genes in this DNA are acting in the human and murine systems. These results indicate that the human cell transfection system allows detection of transforming genes not effective in the 3T3 system and points out the possibility of detection of additional transforming sequences even in DNAs that do transform murine cells.

Animals↗
PubMed1984

Nonsurgical ovum transfer as a treatment for intractable infertility: what effectiveness can we realistically expect?

Using previously reported human, primate, and cattle reproductive performance data, we developed a mathematical model to predict the cumulative probability of pregnancy per woman per month theoretically obtainable by ovum transfer. We then conducted a preliminary ovum transfer clinical trial and compared the results of that trial to the results predicted by the model. Based on the nine spontaneously ovulating fertile donors and seven spontaneously ovulating infertile recipients available for the trial, the model predicted occurrence of between 0.63 and 8.65 pregnancies during the 6-month period of the study. We actually obtained two pregnancies. The model further predicted, with sufficient numbers of donors to produce one match per ovulation for each prospective patient, that the probability of that patient becoming pregnant from ovum transfer ranges from 0.05 to 0.35 per cycle.

Adult↗
PubMed1983

Short-term variability assessment from abdominal electrocardiogram during the antepartum period.

One hundred eighty-eight patients undergoing antepartum fetal heart rate (FHR) monitoring with abdominal fetal electrocardiogram (ECG) technique were studied with respect to FHR variability derived from fetal R-R intervals. Statistically significant positive correlation existed between various measures of FHR variability and accelerations per minute (p less than 0.01). Insufficient numbers of positive contraction stress tests (CST) were available to establish a relationship with variability, although a trend existed between positive CST and low variability. Postdate pregnancies had significantly higher variability than nonpostdate pregnancies (p less than .05). This mathematical analysis establishes statistical significance between short-term variability and accelerations per minute and application of this technique for assessment of true variability in antepartum testing is possible.

Electrocardiography↗
PubMed1983

Algorithmic analysis of estriol time concentration curves as a guide to timing of amniocentesis for fetal lung maturity.

Utilizing a computerized algorithm which estimates gestational age (GA) by analyses of third trimester plasma estriol (E3) concentration curves, we predicted L/S ratios at the time of 64 amniocentesis indicated for assessment of fetal maturity. In the identification of immature fetuses, both methodologies concur in 95% of cases if an L/S ratio of less than or equal to 2.3 and projected GA of less than or equal to 36 weeks are accepted as cut-off points. In the identification of mature fetuses there is agreement in only 54% of cases if an L/S ratio of greater than or equal to 2.3 and projected GA of greater than or equal to 37 weeks are accepted as cut-off points. The data show that the E3 algorithm is of value in the postponing of premature and therefore unnecessary amniocenteses for fetal maturity. However the poor correlation between the E3 algorithm, a method previously shown to be accurate in GA prediction, and mature L/S ratios demonstrates the need to utilize more accurate indicators of mature amniotic fluid surfactant activity in future investigations.

Amniocentesis↗
PubMed1980

An algorithm for determining gestational age from unconjugated estriol levels.

Between the 30th and 40th weeks of gestational age (GA), plasma unconjugated estriol (E3) concentrations plotted as a logarithmic function of GA describe a complex bimodal curve. The maximum concentrations for the first peak (GAmax1) occur at approximately 34 weeks' GA, those for the second peak (GAmax2) occur at approximately 38 weeks' GA, and a between-mode nadir occurs at 35 weeks' GA. Using the close relationship between the features of this curve and GA, a computerized algorithmic curve analysis is devised for the estimation of GA during the third trimester of pregnancy. This report describes the algorithm, its clinical application, and its preliminary performance.

Computers↗
PubMed1980

Time trend analysis of unconjugated estriol concentrations in third-trimester pregnancy.

Utilizing a plasma pooling procedure to control short-term pulsatile variability of unconjugated estriol (E3) concentrations, the authors evaluated time trend curves in 42 subjects after normalizing time trend curves in 42 subjects after normalizing gestational age (GA) by a computerized algorithm. Semilogarithmic plots from individual subjects and a median plot derived from pooling the 42 subjects describe complex bimodal curves beginning with an initial steep rise at 30 to 32 weeks' GA, a peak between 32 and 34 weeks' Ga, a transient nadir at 35 weeks' GA, a second steep rise between 35 and 37 weeks' Ga, a second peak between 37 and 39 weeks' Ga, and a downward segment just prior to parturition. Predicted GAs at delivery obtained from individual curve analyses concurred with pediatric GAs within 2 weeks or less in 41 or 42 pregnancies.

Estriol↗
PubMed1978

Comparison of quinestrol and Tace for relief of postpartum breast discomfort.

A single 2-mg dose of quinestrol was demonstrated safe and effective for controlling postpartum lactation and for alleviating breast discomfort. A double-blind comparison to Tace 72 mg every 12 hours for 2 days, and to placebo, was made in 134 patients. The single oral dose of quinestrol showed efficacy equal to the 2-day regimen of Tace. Both were superior to placebo.

Adolescent↗