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Biomedical subjects

D Briggs

Publications and source records attributed to D Briggs.

At least 73 records · Page 4Linked to original sources
PubMed1991

Left ventricular function immediately after exercise in elite cyclists.

To determine the response to exercise of the left ventricle of endurance-trained athletes, 6 elite (world class) cyclists were compared to 6 untrained healthy control subjects. In athletes the stroke volume increased with exercise. In untrained volunteers the stroke volume did not change with exercise. This difference of the response of the stroke volume to exercise reflected a difference of the left ventricular end-diastolic volume. In athletes the left ventricular end-diastolic volume tended to increase. In control subjects the end-diastolic volume decreased. In conclusion, athletes increased cardiac output by increasing stroke volume and heart rate, whereas control subjects increased their cardiac output only by increasing their heart rate.

Adolescent↗
PubMed1991

Abortion in South Australia, 1971-86: an update.

Official statistics on abortion in South Australia for the period 1971-86 are analysed in terms of incidence, age of patients and nuptiality, reasons for abortion, method of termination, period of gestation, previous abortions and concurrent sterilisation. Demographic implications are discussed and recommendations are made for more education and counselling, especially for younger and unmarried women for whom the incidence of abortion seems to be rising.

Abortion, Induced↗
PubMed1990

Poly(dimethylsiloxane)-poly(ethylene oxide)-heparin block copolymers. III: Surface and bulk compositional differences.

Previously observed bioactivity of poly(dimethylsiloxane)-poly(ethylene oxide)-heparin (PDMS-PEO-Hep) triblock copolymers has prompted studies of the surface and bulk character of this copolymer using angular-dependent electron spectroscopy for chemical analysis (ADESCA), static secondary mass spectroscopy (SIMS), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Because the low-energy PDMS phase dominates surfaces of this copolymer when solvent cast under air or vacuum conditions, attempts were made to explain surface restructuring and rearrangements induced in hydrated or aqueous environments that permit surface accessibility and bioactivity of heparin moieties. Based on comparisons with PDMS, PEO, and heparin homopolymers, PEO/heparin blends, and an unheparinized PDMS-PEO diblock copolymer, PDMS-PEO-heparin demonstrates both phase-mixed and phase-separated regions in DSC analysis. During annealing cycles above the Tg values of the copolymer constituents, phase-mixed regions become increasingly phase separated and PEO enriched. TGA analysis confirmed the presence block copolymer constituents and presented evidence of intermolecular segmental interactions, hence phase-mixing in the copolymers. ADESCA analysis indicates that the outer 5 A of both the PDMS-PEO and PDMS-PEO-Hep copolymers is essentially pure PDMS. However, significant amounts of PEO are detected 5 to 20 A below the surface. Static SIMS also detects the presence of PDMS at the surfaces of the PDMS-PEO and PDMS-PEO-Hep copolymers. Compositional models based on ADESCA, SIMS, and DSC data are presented for desiccated and hydrated copolymer surfaces.

Biocompatible Materials↗
PubMed1990

Continuous fetal heart rate monitoring and tocodynamometry in routine obstetrical care, fetal stress and non-stress testing, and labor induction in the chimpanzee (Pan troglodytes).

The use of continuous fetal heart rate (FHR) and uterine pressure monitoring in the chimpanzee (Pan troglodytes) by external Doppler transducer and tocodynamometer is described in 1) the routine obstetrical assessment of fetal well-being, 2) oxytocin challenge (stress) testing (OCT) and non-stress testing (NST) for the diagnosis of in utero fetal distress, and 3) induction of labor by intravenous oxytocin infusion, by surgical rupture of the chorio-amniotic membranes (amniotomy), or by a combination of these techniques, as an alternative to Caesarean section for clinical, managemental, or experimental purposes. FHR traces were analyzed during a total of 57 term pregnancies for three basic characteristics: baseline rate, variability, and periodic pattern. Results indicated that continuous FHR monitoring in the chimpanzee can provide a valuable tool for fetal assessment and management of labor in any attempt to reduce the unacceptably high annual incidence of perinatal and neonatal infant mortality reported in the U.S.

Amnion↗
PubMed1990

Genetic factors in scleroderma.

1. In no ethnic group is the overall association between SSc and the MHC, T-cell receptors, or drug metabolism phenotypes strong enough for direct clinical use. 2. Indications are that associations between specific subsets of SSc patients and genetic markers will assume greater importance both diagnostically and prognostically. The lung fibrosis group may be a prime candidate. 3. Genetic markers are useful means of relating chemically induced SSc-like disorders with the classical disease. Vinyl chloride disease is an example. 4. Evidence is emerging of strong associations between certain genetic markers and autoantibody production; a similar story has emerged in SLE. We believe that genetic testing will influence therapy in at least a subset of SSc patients, but that a dramatic breakthrough will not be made until we know how the genetics of the disease relate to the primary biochemical disease characteristic, that is the overproduction of collagen. In this respect, it has been suggested that the 5' flanking DNA of dermal collagen genes is particularly susceptible to the binding by Scl-70 (topoisomerase I). A problem is how to combine this and the other observations discussed above. Chromosomal instability can be linked to both the MHC and SSc-inducing chemicals, and the association of autoantibodies to topoisomerase I provides a tentative link between the MHC and collagen gene expression. Although the role and reason for anti-Scl 70 in SSc is unknown, humoral autoimmunity, at least in SLE, appears to be strongly dependent on specific HLA genes.

Chromosome Aberrations↗
PubMed1989

Direct demonstration of termination signals for RNA polymerase II from the sea urchin H2A histone gene.

Previous studies [1,2] suggested but did not prove that the sea urchin H2A histone gene possesses strong transcriptional termination signals close to, but separate from, the 3' processing signals. In this study we have demonstrated by two independent approaches that these sequences elicit authentic transcriptional termination. First we show by nuclear run off analysis that nascent transcription terminates in the immediate 3' flanking region of the H2A gene, in an A-rich region. Second we show that these termination signals prevent transcriptional read through when placed in the intron of a globin gene. The intronic position of the termination signal rules out any effect on steady state mRNA levels. We have therefore defined DNA sequences which act as a transcription terminator when placed in heterologous RNA polymerase II genes.

Animals↗
PubMed1989

Short-term effects of butylated hydroxytoluene on the Wistar rat liver, urinary bladder and thyroid gland.

Long-term feeding of butylated hydroxytoluene (BHT) to rats and mice has been linked to the enhancement of the incidence of liver tumors. It is shown in this paper that in the liver, urinary bladder and thyroid of the male Wistar rat, feeding the highest tolerated doses of BHT for 30 days does not lead to detectable increases in [3H]thymidine labeling. On the other hand, treatment of rats with 0.5% dietary BHT leads to a time-limited increase in liver cell [3H]thymidine labeling that subsided to control values within 8 days. This increase in [3H]thymidine labeling in the liver is accompanied by an unexpectedly large increase in the mitotic index. These results are discussed in the light of the behavior of certain rodent liver tumorigens.

Animals↗
PubMed1989

Definition of an efficient synthetic poly(A) site.

We constructed and analyzed a synthetic poly(A) (SPA) site that was based on the highly efficient poly(A) signal of the rabbit beta-globin gene. By use of the SPA, we demonstrate that the minimum sequences required for efficient polyadenylation are the AATAAA sequence and a GT/T-rich sequence with the correct spacing of 22-23 nucleotides between them. When placed downstream of the poly(A) site of the human alpha 2-globin gene, the SPA is used exclusively. We predict that the SPA, with its more extensive GT/T-rich sequence, is a more efficient poly(A) site than alpha-globin. Also, we compared the use of the SPA when it is placed either in the exon 3 or intron 2 of the rabbit beta-globin gene. When in the exonic position, SPA is used 10-fold more than the regular poly(A) site of rabbit beta-globin. In contrast, when it is in the intronic location, no detectable use of SPA is observed; however, the deletion of the donor site of intron 2 reactivates the intronic positioned SPA. These results indicate that the splicing of intron 2 in the rabbit beta-globin gene occurs ahead of polyadenylation and have important implications for termination of transcription. Polyadenylation, although required for termination of transcription, is not sufficient; therefore, additional termination signals for RNA polymerase II must exist.

Animals↗
PubMed1988

Knowledge and attitudes of Victorian medical practitioners in relation to the acquired immunodeficiency syndrome.

A stratified random sample of Victorian medical practitioners was surveyed to determine doctors' knowledge of and attitudes to the acquired immunodeficiency syndrome (AIDS). The results of this survey have shown that the knowledge level of a representative sample of medical practitioners in Victoria about AIDS was satisfactory at the beginning of a continuing educational campaign. The knowledge level varied according to the age of the doctor and the specialty of medicine that was practised. Attitudes towards and management practice of AIDS varied according to the specialty and rarely correlated with the knowledge level of the doctor. The majority of doctors who were surveyed had already received queries about AIDS from their patients, and over 90% of doctors thought that medical practitioners have a role to play in educating and counselling patients about AIDS (including preventive measures). In addition, the majority of doctors were receptive to receiving more information about AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1988

HLA antigens in the Guillain-Barré syndrome.

HLA typing for class I and II antigens was performed on 89 caucasoid patients with Guillain-Barré syndrome and compared with controls. No significant association, between HLA type and susceptibility to disease, prognosis at 12 months or antecedent event was discovered. HLA antigen DR2 was more frequent among patients with the most profound muscle weakness.

Campylobacter Infections↗