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Biomedical subjects

A B Roberts

Publications and source records attributed to A B Roberts.

At least 307 records · Page 17Linked to original sources
PubMed1981

New class of transforming growth factors potentiated by epidermal growth factor: isolation from non-neoplastic tissues.

Proteins potentiated by epidermal growth factor (EGF) to induce a transformed phenotype in non-neoplastic rat kidney fibroblasts in cell culture have been isolated from many non-neoplastic tissues of the adult mouse, including submaxillary gland, kidney, liver, muscle, heart, and brain. They resemble previously described transforming growth factors (TGFs) isolated from neoplastic cells as follows: they are extractable by acid/ethanol and are acid-stable, low molecular weight (6000-10,000) polypeptides requiring disulfide bonds for activity; and they cause anchorage-independent growth of non-neoplastic indicator cells that will not grow in soft agar in their absence. Partial purification of these TGFs from submaxillary glands of male mice shows that they are distinct from EGF. Unlike previously described extracellular TGFs, but like certain cellular TGFs from neoplastic cells, they are potentiated by EGF in their ability to promote anchorage-independent growth. The isoelectric point of the submaxillary gland TGF protein is near neutrality. Chromatography on Bio-Gel P-30 followed by high-pressure liquid chromatography has resulted in a 22,000-fold overall purification. The most purified protein is active in inducing growth in soft agar at 1 ng/ml when assayed in the presence of EGF. The data add further evidence to the concept that neoplasia may result from a quantitative, rather than qualitative, alteration in non-neoplastic biochemical processes.

Animals↗
PubMed1980

In vitro and in vivo metabolism of all-trans- and 13-cis-retinoic acid in hamsters. Identification of 13-cis-4-oxoretinoic acid.

Administration of either all-trans-[3H]- or 13-cis-[3H]retinoic acid to hamsters fed a normal diet results in the formation of a number of polar metabolites. At least one of these metabolites has been shown to be common to both isomers of retinoic acid and can be generated in a hamster liver 10,000 X g supernatant system using 13-cis-retinoic acid as substrate. It has been identified as 13-cis-4-oxoretinoic acid by mass spectral, ultraviolet absorption, and proton NMR characteristics, as well as by its co-migration with synthetic 13-cis-4-oxoretinoic acid in two different high pressure liquid chromatographic systems. In addition, its metabolic precursor, 13-cis-4-hydroxyretinoic acid, has been tentatively identified. These compounds are believed to be early metabolites in the elimination pathway of retinoic acid from the body.

Animals↗
PubMed1980

Transforming growth factors: isolation of polypeptides from virally and chemically transformed cells by acid/ethanol extraction.

Polypeptides characterized by their ability to confer a transformed phenotype on an untransformed indicator cell have been isolated directly from tumor cells growing both in culture and in the animal, by using an acid/ethanol extraction procedure. Assay of these polypeptides is based on their ability to induce normal rat kidney fibroblasts to form colonies in soft agar. Peptides from murine sarcoma virus-transformed mouse 3T3 cells grown in culture had the highest specific activity in this assay; peptides from sarcomas produced from these cells or from chemically induced transplantable bladder carcinomas of mice were one-third as active; and peptides from a chemically induced rat tracheal carcinoma had only one-tenth the activity. Treatment with either trypsin or dithiothreitol destroyed the activity of all of these materials. The properties of these intracellular polypeptides from both virally and chemically transformed cells are similar to those described for the sarcoma growth factors (SGFs) previously isolated from the conditioned medium of sarcoma virus-transformed mouse 3T3 cells, suggesting the definition of a class of transforming growth factors common to tumor cells of different origins. The transforming peptides from the cultured sarcoma virus-infected cells were separately by gel filtration into two fractions of apparent molecular weight 7000 and 10,000. The major fraction at molecular weight 7000 represented approximately 0.1% of the original cell protein and had a specific activity 50 times that of the original acid/ethanol extract.

Animals↗
PubMed1980

Fetal activity in 100 normal third trimester pregnancies.

The incidence of fetal breathing movements (FBM), fetal trunk movements (FTM), and total fetal activity (TFA) was assessed in 100 normal pregnancies between 28 weeks and term. One 30-minute recording was made from each patient between 0900 and 1700 hours. The mean incidences of FBM, FTM and TFA were respectively 37 +/- 26 (SD) per cent, 18 +/- 10 per cent, and 53 +/- 24 per cent. The mean breathing rate was 48 +/- 12 per minute, and the mean nunber of movements per 30-minute study period was 29 +/- 15. There was a slightly higher incidence of FBM postprandially, but this failed to reach statistical significance. The mean incidence of FBM was lower before 31 weeks and after 40 weeks, compared to that between 31 and 40 weeks, when the values of FBM and FTM were constant. The breathing rate was directly related to gestational age. The mean number of movements per 30-minute study period was inversely related to gestational age, but the duration of movements increased progressively towards term, so that the incidence of FTM was constant throughout the third trimester. There was only one recording of TFA below 10 per cent.

Adolescent↗
PubMed1979

Maternal perception of fetal motor activity.

A technique using real-time ultrasound for comprehensive recording of fetal motor activity was used in 20 subjects in the third trimester of pregnancy. Maternal awareness of fetal movement correlated with the number of fetal parts contributing to the movement but not with maternal parity or obesity, gestational age, placental site, or duration of the fetal movement. Some subjects recorded fetal breathing, passive fetal displacement, and Braxton Hicks's contractions as fetal movement. Most of our subjects were consistent and accurate in their perception of major fetal movements, but a few were inconsistent and one was completely unaware of major fetal movements. These results suggest that kick counts kept by most mothers will be accurate. Low counts of fetal movement should be an indication for fetal monitoring by other means and not, unconfirmed, for intervention.

Female↗
PubMed1979

Isolation and identification of 4-hydroxy- and 4-oxoretinoic acid. In vitro metabolites of all-trans-retinoic acid in hamster trachea and liver.

Incubation of [3H]retinoic acid in the presence of hamster liver 10000g supernatant produces several metabolites that are more polar than the parent compound. Two of these metabolites are identical with synthetic all-trans-4-hydroxyretinoic acid and all-trans-4-oxoretinoic acid both in ultraviolet absorption and mass spectral characteristics and in migration rates on two different reverse-phase high-pressure liquid chromatographic systems. The metabolites produced in a cell-free liver incubation reaction also migrate on a high-pressure liquid chromatography column together with metabolites isolated from a tracheal organ culture system. Both the metabolites and the synthetic standards show less biological activity than the parent all-trans-retinoic acid in a tracheal organ culture assay.

Animals↗
PubMed1979

Normal patterns of fetal activity in the third trimester.

The incidence and frequency of fetal respiratory movements (FRM) and fetal trunk movements (FTM) were measured in 21 normal pregnancies between 28 and 39 weeks gestation. Fetal activity was assessed with a real-time ultrasound scanner and all observed movements were punched directly onto computer tape. Recordings were made for one hour in three over a 24 hour period, providing a total of 168 hours for analysis. The overall mean percentage incidence of FRM was 31 per cent at a mean breathing rate of 43 breaths/minute. The mean percentage incidence of FRM during the day (0800-1759 hours) was 37 per cent. The overall mean percentage incidence of FTM was 18 per cent with a mean of 29 moves per 30 minute observation period. The mean percentage incidence of FTM during the day (0800-1759 hours) was 16 per cent. There was a well-defined circadian variation in fetal activity with FRM peaking between 1900 and 2200 hours, and FTM between 2200 and 0100 hours. There was considerable variation in the amount of FRM and FTM recorded from hour to hour. Total fetal activity rarely fell below 10 per cent in any one recording period and this measurement may be a more useful clinical test of fetal well-being than FRM or FTM alone.

Adolescent↗
PubMed1979

Cholera in the Gilbert Islands. II. Clinical and laboratory findings.

An epidemic of cholera due to Vibrio cholerae biotype El Tor occurred in 1977 on Tarawa in the Gilbert Islands. No cholera epidemic had occurred there previously and special problems were encountered in both the diagnosis and clinical management. The clinical features of the 585 hospital admissions on Tarawa during the first 64 days of the epidemic were recorded. Eight hospital deaths occurred in this period. A marked increase in cholera among malnourished Gilbertese children was noted. Simplified regimes for management were devised for the circumstances including schemes for oral and intravenous rehydration. Coconut water was used extensively in oral rehydration. Paramedical personnel were used effectively during the epidemic. Prophylactic tetracycline was used in household contacts of patients and was effective in reducing subsequent illness.

Cholera↗
PubMed1979

Recent advances in the in vivo and in vitro metabolism of retinoic acid.

Retinoic acid, a natural metabolite of retinol, has previously been shown to be capable of supporting growth and maintaining proper differentiation in epithelial tissues. Recently, investigation into the in vivo and in vitro metabolism of retinoic acid in hamsters, using both tracheal organ culture and subcellular preparations derived from intestinal mucosa, liver, and testis, has revealed the production of several metabolites more polar than the parent compound. Two of the early products of this metabolic pathway have been identified as 4-hydroxy- and 4-keto-retinoic acid. The formation of these metabolites is maximal in vitamin A-deficient hamsters that have been pretreated with retinoic acid and in vitamin A-normal animals. This fact, together with the decreased biological activity of the two compounds relative to retinoic acid in a tracheal organ culture assay, suggested that oxidative attack at carbon-four of the cyclohexenyl ring may be the first step in the elimination of retinoic acid from tissues. In addition, observations both in vivo and in vitro indicate that all-trans- and 13-cis-retinoic acid at low concentrations may be sharing a common metabolic pathway that includes an isomer of 4-keto-retinoic acid.

Animals↗
PubMed1978

Comparison between subjective and ultrasound assessments of fetal movement.

Forty pregnant women participated in a study to compare subjective with ultrasound assessments of fetal movements. A real-time ultrasound scanner was used. Movements were recorded for 45 minutes in all cases. There was a significant positive correlation between the number of movements recorded by the two methods, but the 95% confidence limits were wide and no correlation was found in those patients who recorded fewer than 20 movements in the study period. Thus "false-positive" information may be obtained from purely subjective data, and in patients reporting low "kick counts" fetal activity should be assessed from real-time ultrasound recordings.

Female↗