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Biomedical subjects

A J Davis

Publications and source records attributed to A J Davis.

At least 127 records · Page 7Linked to original sources
PubMed1991

Mechanism of secretion of plasma insulin-like growth factor-I into milk of lactating goats.

125I-Labelled insulin-like growth factor-I (IGF-I) was infused as the free form directly into the pudic artery supplying one gland of lactating goats (n = 6). The infusion was for 60 min and 0.4 +/- 0.09% (S.E.M.) of the infusate was secreted into milk from the infused gland during its first passage through that gland. A large proportion of the 125I-labelled IGF-I escaped into the systematic circulation and was secreted into milk of both glands. A total of 5.2 +/- 0.4% of infused radioactivity was recovered in milk from both glands from 0 to 720 min. Radioactivity consisted of trichloroacetic acid (TCA)-precipitable and -soluble counts which were shown by gel filtration to be authentic IGF-I and degraded products of the peptide. The amount and time course of TCA-soluble radioactivity in milk from both glands was similar, suggesting degradation of 125I-labelled IGF-I at extramammary sites. Maximum specific activity for 125I-labelled IGF-I in milk from the infused gland was reached 80-120 min after the start of infusion and was 2.5-fold greater than milk from the non-infused gland. The time course of appearance of 125I-labelled IGF-I in milk suggests that transfer was via the transcellular pathway and this was further supported by comparing the pattern of transfer of [14C]sucrose and [14C]amino acids. When excess unlabelled IGF-I was included in the infusate, specific activity in milk from the infused gland was reduced to that of the non-infused gland, indicating a competitive and saturable mechanism of secretion for 125I-labelled IGF-I.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Recombination of pseudorabies virus vaccine strains in swine.

We report here genetic recombination between 2 USDA-licensed vaccine strains of pseudorabies virus co-inoculated into swine. The vaccine strains, one of which was a conventionally attenuated strain and the other, a genetically engineered deleted strain containing a negative immunologic marker, had complementary genomes. Co-inoculation resulted in the creation of novel strains of pseudorabies virus containing negative immunologic markers with restored virulence genes. Plaque-purified recombinant progeny viruses were found in 2 litters of pigs in which both strains were co-inoculated IM, a litter in which both strains were co-inoculated oronasally, and a litter in which the conventionally attenuated strain was inoculated oronasally and the genetically engineered strain was inoculated IM. Recombinant phenotypes and recombinant restriction fragment patterns were observed. The creation, spread, and potential misdiagnosis of these types of recombinant strains could disrupt control and eradication programs that are based on the serologic identification of swine infected with potentially virulent strains of pseudorabies virus.

Animals↗
PubMed1990

Subsequent asynchronous torsion of normal adnexa in children.

Children who have suffered from ovarian torsion may be at increased risk for a repetitive event. Torsion in a normal adnexa may be due to excessive mobility resulting from congenitally long supportive ligaments. Oophoropexy or shortening of the ligamentous support of the remaining functional ovary after torsion is recommended in attempt to prevent a subsequent torsion. The evaluation of young females with abdominal pain should always include the consideration of ovarian torsion. Preoperative ultrasonography is not invasive and could lead to earlier operative intervention resulting in salvage of ovarian tissue. Observation in these same children may allow a torsed edematous ovary to convert to a nonviable necrotic tissue necessitating oophorectomy. Laparoscopy is useful in cases in which the diagnosis is unclear.

Child↗
PubMed1990

The good nurse: descriptions from the People's Republic of China.

This study is based on questionnaire data gathered from 33 students in the first class of the first BSN programme in the People's Republic of China. They were asked to describe the characteristics of a good nurse and characteristics of a bad nurse. These students had just completed their pre-nursing courses and were entering the nursing part of their education. They identified personal qualities, behaviour and knowledge areas as the overall categories for these characteristics.

China↗
PubMed1989

Genetic analysis of attTn7, the transposon Tn7 attachment site in Escherichia coli, using a novel M13-based transduction assay.

The large (14 kb; kb = 10(3) bases) bacterial transposon, Tn7 (encoding resistance to trimethoprim and streptomycin/spectinomycin), has unusual properties. Like other elements, Tn7 transposes with low efficiency and low target-site specificity, but Tn7 also transposes, with high frequency in a unique orientation, to a preferred "attachment" site, called attTn7, in the Escherichia coli chromosome and similarly into plasmids containing attTn7. We developed a novel bacteriophage M13-based assay system to measure the transposition frequency of Tn7 to M13mp phage vectors containing attTn7 on a cloned 1 kb fragment of chromosomal DNA. Phage harvested from a Tn7 donor strain were used to infect recipient bacteria with selection for trimethoprim resistance. Transposition frequency, expressed as the number of trimethoprim-resistant colonies per plaque-forming unit, was found to be approximately 10(-4) to M13mp::attTn7, in contrast to 10(-10) to M13mp recombinants with approximately 1 kb insertions of other, "generic brand", DNA. By deletion analysis of M13mp::attTn7, we show that attTn7 is contained within a 64 base-pair region; sequences adjacent to the actual insertion site and encoding the carboxy terminus of the glmS gene are required. This assay also provided evidence for transposition immunity conferred by the right end of Tn7.

Attachment Sites, Microbiological↗
PubMed1989

The competency quagmire: clarification of the nursing perspective concerning the issues of competence and informed consent.

Selected issues involved in informed consent and the patient's competence to give it are examined. A discussion of tests of competence reveals some of the problems encountered in using them. There are differences in medical and nursing functions and responsibilities in the informed consent process. One nursing framework, self care, is used to discuss whether informed consent should be obtained from patients when they receive specific nursing care.

Attitude of Health Personnel↗
PubMed1989

Clinical nurses' ethical decision making in situations of informed consent.

Based on responses to vignettes and semistructured interviews with 27 nurses working in two clinical settings, data were gathered focused on nurses' ethical decision making in situations of informed consent. A content analysis of the interviews revealed that the most potent variables at play in these situations were institutional and philosophical influences. Aspects of these influences are discussed.

Attitude of Health Personnel↗
PubMed1989

U.S. and Australian nurses' attitudes and beliefs about the good death.

The purpose of this study was to ascertain the attitudes and beliefs of nurses in Australia and the United States regarding aspects of passive euthanasia, or the "good death." Two foci guided the study: (a) the possible discrepancies that these nurses might perceive between what they thought would be done in a given clinical situation and what they thought ought to be done, and (b) the possible differences and similarities between the American and the Australian nurses. Responding to the 8 vignettes, 30 American and 32 Australian nurses took part in the study. The lack of agreement between the Australian and American nurses on issues of euthanasia reflects differences in the health care system; the general social position of nursing as a profession; the relationship among health professionals, patients and families, which serves as the context for definition of ethical duties and patient rights; and the role of the law in health care decisions.

Adult↗
PubMed1989

Neurotransmitters and lymphatic-vascular transfer of prostaglandin F2 alpha stimulate ovarian oxytocin output in sheep.

The mechanisms of lymphatic-vascular transfer across the ovarian vascular pedicle were studied in anaesthetized sheep 8-15 days after ovulation. [3H]Prostaglandin F2 alpha (PGF2 alpha), [14C]mannitol and [36Cl]Na were infused continuously into either a uterine lymphatic or a uterine vein and the kinetics of transfer into the adjacent utero-ovarian vein or ovarian plasma were studied. Transfer occurred according to the sequence [36Cl] greater than [14C] greater than [3H] indicating that PGF2 alpha is not transferred by rapid diffusion, as with [36Cl]Na, nor by a paracellular route, as with [14C]mannitol, but by a slower process probably involving facilitated diffusion. Transfer into the adjacent utero-ovarian vein or ovarian blood was greater when compounds were infused into a uterine lymphatic than into a uterine vein. Substantially more [3H]PGF2 alpha occurred in the adjacent corpus luteum than either of the other compounds after a lymphatic infusion. Intra-lymphatic infusion of PGF2 alpha stimulated the release of ovarian oxytocin but the effect was not confined to the adjacent ovary. Intravenous (jugular) infusion of PGF2 alpha failed to stimulate ovarian oxytocin secretion whereas close-arterial infusion into the ovaries was effective, and the possibility was investigated that any systemic effect of PGF2 alpha was mediated through neural mechanisms. Noradrenaline and acetylcholine were both effective in causing the release of ovarian oxytocin when infused close-arterially into the ovary. With infusions of acetylcholine, ovarian oxytocin secretion rate was increased over fivefold without any change in posterior pituitary release. Noradrenaline and acetylcholine produced a concomitant fall in ovarian blood flow, and neurotransmitter-induced ischaemia may have played a role in ovarian oxytocin release. The finding that PGF2 alpha infused into a uterine lymphatic stimulates ovarian secretion of oxytocin, and that the effect is bilateral whereas PGF2 alpha accumulation in ovarian tissue is unilateral, implies that its mechanism of action may not be solely directed at the luteal cell.

Acetylcholine↗