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Biomedical subjects

M Gray

Publications and source records attributed to M Gray.

At least 181 records · Page 10Linked to original sources
PubMed1985

Reanalysis of the equation for simple action.

De Villiers and Herrnstein (1976) have shown that the equation for simple action, derived from the matching law, predicts change in behavioral output for some 40 experiments in which the value of a single source of reinforcement has been varied. Using only the positive-reinforcement studies they cite that used five or more different reinforcement values, we found the high percentage of variance they report accommodated by this equation (94%) is predicated on instances of averaging rates of behavioral output before making a least-squares fit of the equation. In our reanalysis, which minimizes rate averaging, only 78% of the data variance is accommodated. This diminished data-variance accommodation can be improved by adding parameters that permit the equation's scaling constant to change as a function of reinforcement. Although these parameters permit acceptable levels of accommodation of data variance, they correspond to no obvious psychological processes. These findings support the view that the equation for simple action is an inadequate model for behavioral output.

Journal Article↗
PubMed1984

Facilitating prevention in primary care.

We believe that many general practitioners would practice preventive medicine if they had the opportunity to organise their practice to do this. We therefore provided a "facilitator," who understands the work of a general practice, to help practices that were interested in prevention to set up programmes. She, for example, helped the primary care team to set up objectives, trained practice nurses to measure blood pressure, and set up a system to measure the progress of the programme.

Adult↗
PubMed1984

Upper genital tract abnormalities and pregnancy outcome in diethylstilbestrol-exposed progeny.

Previous studies have suggested that there is an association between genital tract abnormalities and pregnancy outcome in women exposed to diethylstilbestrol (DES) in utero. In a collaborative study, 676 DES-exposed women had hysterosalpingographic examinations, and the findings were related to the outcome of pregnancy in 327 of these women. The findings revealed that (1) there is a considerable variation of frequency of different types of upper genital tract anomalies in women from different sources and with different motivations for enrollment in the study, (2) the presence of structural cervical changes and vaginal epithelial changes are markers for the likelihood of abnormalities in the uterine fundus, (3) women with upper genital tract abnormalities have increased odds for poor pregnancy outcome as compared to women with normal hysterosalpingographic findings, and (4) although some abnormalities were most often or consistently associated with poor pregnancy outcome, no specific changes could be related to specific types of pregnancy outcomes.

Abortion, Spontaneous↗
PubMed1984

Efficacy of a real-time digital disk in the digital lightbox.

This paper describes a high-speed digital lightbox. The current status of film in the medical imaging department sets the stage for this next generation of image display/management systems. Digital imaging devices are proliferating because of their diagnostic speed and accuracy, and their ease of use. However, the resultant images are usually prepared by a technician, transmitted to film, then mounted on a lightbox to be eventually reviewed by the physician. Until recently, the shortcomings of a film display system could be overlooked in favor of its data-acquisition and archiving advantages. With recent developments in real-time disks and high-resolution display systems, it is now possible to improve upon the physician's display with a digital lightbox. A unique Multimodality Acquisition and Review System (MARS) is described that will support this new digital lightbox with performance features that meet or exceed the characteristic use of film in today's medical imaging departments.

Data Display↗
PubMed1983

Antenatal detection of grossly distended bladder owing to absence of the urethra in a fetus with trisomy 18.

An ultrasonic examination revealed a grossly distended fetal abdomen. Amniocentesis at 19 weeks' gestation showed raised amniotic fluid alphafetoprotein, a second band of specific acetylcholinesterase, and a fetal karyotype 47,XY,+18. The pregnancy was terminated and the necropsy examination showed absence of the urethra, grossly distended bladder, hydroureters, and congenital heart anomalies.

Adult↗
PubMed1983

Effects of age, gender, and cigarette smoking on human immunoregulatory T-cell subsets: establishment of normal ranges and comparison with patients with colorectal cancer and multiple sclerosis.

Normal ranges for peripheral circulating mature functional T cells (OKT3+), T helper-inducer cells (OKT4+), and T cytotoxic-suppressor cells (OKT8+) were determined in 161 normal male and female volunteers. Children between 5 and 15 years of age showed higher circulating OKT3+ cell numbers than adults, and in male children the circulating OKT4+ cell number was also higher. In adults, females demonstrated higher circulating OKT4+ cell numbers than males, and smokers demonstrated higher circulating numbers of both OKT3+ and OKT4+ cells than nonsmokers. There was a significant interaction between gender and smoking, with female smokers exhibiting the highest circulating OKT3+ cell numbers. Two groups of patients entering longitudinal T-cell subset monitoring studies were compared to their appropriate normal control groups. It was found that 48% of patients with colorectal cancer were T-cell (OKT3+) lymphopenic at presentation, and that 62% had a low OKT4/OKT8 ratio. Colorectal surgery tended to correct this T-cell lymphopenia. However, only transient rises in low OKT4/OKT8 ratios were observed after surgery. Of 11 patients with multiple sclerosis in a trial of transfer factor therapy, 7 were found to have high OKT4/OKT8 ratios prior to treatment; these ratios have persisted to date during treatment.

Adolescent↗
PubMed1982

Characterization of Giemsa dark- and light-band DNA.

Using synchronized cultures of V79-8 Chinese hamster lung fibroblasts, we either alternately labeled early- and late-replicating DNA, or substituted one of these with bromodeoxyuridine to separate them in CsCl density gradients or to identify the bromodeoxyuridine-containing chromosome bands by fluorescence microscopy. The Giemsa light R bands were shown to replicate in the first half of S phase, and the dark G bands were shown to replicate in the last half of S phase. S phase was bimodal, with a distinct pause in the rate of DNA synthesis that separated the period of R-band DNA synthesis from that of G-band DNA synthesis. G-band DNA was found to be 3.2% richer in AT than R-band DNA. Surprisingly, G- and R-band DNA appeared equally transcriptionally active in that alternate labels in chromatin were digested with the same kinetics by DNAase I, and in reassociation experiments, total poly(A)+ RNA drove nick-translated G- and R-band DNA probes similarly. G- and R-band DNA also reassociated with identical kinetics, demonstrating that they contain equal proportions of all kinetic-complexity classes of sequences.

Animals↗
PubMed1982

Potentiation of radiation injury by interferon.

Interferon (IFN) is being tested clinically in the treatment of a wide range of human malignancies. Patients undergoing cancer treatment may require radiotherapy in conjunction with IFN administration. This study examined the effect of purified preparations of IFN on the radiation response of mouse Swiss 3T3 cells in culture. Cells were exposed to 10 U/ml of mouse IFN or human IFN 2 hours prior to radiation. The IFN was left in the medium for the duration of the experiment. Marked enhancement of radiation response was observed in the presence of mouse IFN as compared to human IFN or no IFN treatment. The difference in radiation response was due to a reduction in the shoulder portion of the survival curve with no change in the slope of the exponential portion. Since human IFN was inactive in these experiments, the data suggest that the potentiation of radiation damage is specific for mouse IFN. The reduction in the shoulder in the presence of mouse IFN suggests the inhibition of the ability of cells to accumulate sublethal radiation injury. Split-dose experiments to test for sublethal radiation injury repair capacity failed to demonstrate an IFN effect. We conclude from these studies that IFN potentiates radiation injury. In clinical situations in which IFN is used, careful monitoring of dosage and timing of irradiation may be required to avoid excessive tissue damage. Moreover, treatment strategies may be directed to time radiation and IFN to obtain an improved therapeutic ratio.

Animals↗