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Biomedical subjects

J Edwards

Publications and source records attributed to J Edwards.

At least 91 records · Page 5Linked to original sources
PubMed1993

Molecular cloning and characterization of p64, a chloride channel protein from kidney microsomes.

Chloride channels were previously purified from bovine kidney cortex membranes using a drug affinity column. Reconstitution of the purified proteins into artificial liposomes and planar bilayers yielded chloride channels. A 64-kDa protein, p64, identified as a component of this chloride channel was used to generate antibodies which depleted solubilized kidney membranes of all chloride channel activity. This antibody has now been used to identify a clone, H2B, from a kidney cDNA library. Antibodies, affinity-purified against the fusion protein of H2B also depleted solubilized kidney cortex from all chloride channel activity. The predicted amino acid sequence of p64 shows that it contains two and possibly four putative transmembrane domains and potential phosphorylation sites by protein kinase A, protein kinase C, and casein kinase II. There was no significant homology to other protein (or DNA) sequences in the data base. The protein is expressed in all cells tested. Expression of its mRNA in Xenopus laevis oocytes led to the insertion of a protein with the appropriate molecular mass in microsomes but not in the plasma membrane. It is likely that p64 represents the chloride channel of intracellular organelles.

Amino Acid Sequence↗
PubMed1993

A comparison of tumor and normal tissue microvascular hematocrits and red cell fluxes in a rat window chamber model.

This laboratory has previously used a window chamber model to measure red blood cell velocity in mammary tumors and normal granulation tissues of the F-344 rat. Because red cell flux and hematocrit more accurately reflect the oxygen carrying potential of blood, we used this model to measure these parameters. Red blood cells were labelled with fluorescein isothiocyanate, and 0.2 ml. packed cells were injected intravenously into rats bearing an 8 to 10 day old R-3230 mammary carcinoma. beta-phycoerythrin (0.15 mg.) was also injected and served as a plasma dye to outline the blood vessels. A sample of peripheral blood was then taken and analyzed by flow cytometry to determine the labeled fraction of red blood cells. Flowing tumor and normal tissue vessels were recorded onto a VCR, and these video images were used to determine vascular length and diameter, RBC flux and velocity, and hematocrit. Median vessel diameter and loge (red blood cell flux) were significantly greater in tumors than in normal tissues (p = 0.007 and p < 0.025, respectively). After controlling for these variables, the median tumor hematocrit of 19% was not significantly greater than the median normal tissue hematocrit of 15%. This technique provides a nontoxic and reproducible method that is now being used to assist in the in vivo definition of tumor oxygenation.

Animals↗
PubMed1993

Auditory lexical decisions in children and adults: an examination of response factors.

This study examined the influence of nonlexical response factors on the speed of auditory lexical decisions in children and adults. Two groups of children (6- and 7-year-olds, 8- and 9-year-olds) and adults participated in three tasks: a real-word lexical decision task in which subjects were asked to say "yes" as quickly as possible to real words; a nonword lexical decision task in which subjects were asked to say "no" as quickly as possible to nonwords; and an auditory-vocal reaction time task in which subjects were asked to say "yes" or "no" to a tone. Response times on all tasks decreased with age. However, the age-related differences on the real-word lexical decision task disappeared when differences in auditory-vocal reaction times were taken into account. This result suggests that a large part of developmental differences in the speed of lexical processing may be due to nonlexical response factors.

Adult↗
PubMed1993

Effect of extradural analgesia on stress responses to abdominal surgery in infants.

We studied 40 children younger than 4 yr having elective abdominal surgery under general anaesthesia supplemented with either systemic opioids or extradural bupivacaine. Venous blood samples were obtained before tracheal intubation to measure baseline concentrations of adrenaline, noradrenaline, glucose, ACTH and cortisol. Additional samples were obtained 45 min after the start of surgery, at the end of surgery, 1 h and 24 h after the end of surgery. Plasma concentrations of bupivacaine were measured also in the extradural group at each sampling time. Both techniques provided acceptable analgesia, but the perioperative increases in adrenaline, glucose and ACTH were significantly greater in the opioid group. Noradrenaline concentrations decreased to less than baseline values in the extradural group and were significantly less than in the opioid group. The perioperative increase in cortisol was similar in the two groups, despite the differences in ACTH responses. Most responses returned to the baseline values within 24 h. Plasma bupivacaine concentrations remained within safe limits during the study, but systemic concentrations increased in some of the patients during postoperative infusion with 0.125% bupivacaine.

Abdomen↗
PubMed1993

Caregiver-infant interaction--comforting post-operative neonates.

Analysis of 40 h of videotaped caregiving to four male infants was conducted using ethology. All infants were full term and had major chest surgery 12 h previously. All incidents of caregiver-infant interaction were examined, and the verbal and tactile comforting behavior of the caregiver was coded for duration, context, infant cue and infant state prior and following the interaction. A total of 191 comforting incidents occurred during the study. Stroking was the most common form of touch used. Most of the comforting (60%) was given in the context of caregiving; sleeping infants were touched often (38%); 25.3% of the touches were given to acutely distressed infants, and wide awake infants relatively little. Most of the infants showed no change in infant state after the relatively brief comforting incidents, but in 15.7% of the incidents the infants 'settled' after comforting. The authors conclude that this is a relatively strong effect considering the short duration of the comforting actions.

Caregivers↗
PubMed1993

Effects of endotoxin in vivo on endothelial and smooth-muscle function in rabbit and rat aorta.

In order to determine whether endotoxemia induced generalized defects in vascular contraction and endothelium-dependent relaxation, we studied the effect of in vivo endotoxin administration in Sprague-Dawley rats and New Zealand White rabbits on endothelial and arterial smooth-muscle responses of isolated thoracic aorta in vitro. Endotoxin treatment significantly decreased contractile responses to phenylephrine (PE), angiotensin II (AII), serotonin (5-HT), and potassium chloride. This effect was not altered by indomethacin or endothelial denudation. Treatment of vessels with NG-nitro-L-arginine (NNLA), an inhibitor of arginine-dependent nitric oxide biosynthesis, or with methylene blue, an inhibitor of soluble guanylate cyclase, resulted in significant improvement of the contractile defect in endotoxin-treated vessels. The restorative effect of NNLA on contractile responses in endotoxin-treated aortic rings was similar in the presence or absence of an intact endothelium. Endothelium-dependent relaxation in response to acetylcholine, substance P, or the calcium ionophore A23187 was markedly impaired in vessels from endotoxin-treated rabbits, while endothelium-independent relaxation in response to nitroprusside was similar in both groups. These results suggest that endotoxemia both induces basal, nonendothelial nitric oxide synthesis and impairs the agonist-stimulated release of endothelium-derived relaxing factor (EDRF). These findings may have mechanistic importance in the hemodynamic derangements of endotoxemia.

Angiotensin II↗
PubMed1993

Types of health problems and satisfaction with services in a rural nurse-managed clinic.

The purpose of this study was to investigate the satisfaction of clients with care provided in a rural nurse-managed health center by family nurse practitioners and to describe common health problems for which family nurse practitioner services were sought. The results indicated that of the 2,106 visits from a case load of 1,350 clients, acute health problems were the most common (95.7%), and chronic health problems were the least common (3.9%). Respiratory and ear infections were the most frequent acute illness (55%), and hypertension (29%), respiratory (27%), and musculoskeletal complaints (27%) were the most frequent chronic conditions. Children up to 6 years of age constituted the largest client population (30%), followed by young adults (23%). Older adults were the smallest numbers of clients (3%). Client satisfaction with nurse practitioner-managed care was highly rated by 97% (n = 101) of the subjects in a random sample telephone survey. The results suggested that family nurse practitioners were providing effective and satisfactory healthcare for this rural community. Issues for further investigation are also discussed.

Adolescent↗
PubMed1993

Undercover 'shopping' to evaluate lab services.

Wonder what goes on at your outpatient labs when you're not there? This clever adaptation from the retail world can help you ferret out foul play and affirm first-rate employees.

Consumer Behavior↗
PubMed1993

Youth suicide in the Australian Capital Territory.

A study was made of all suicides of young people aged under 25 years in the Australian Capital Territory (ACT) over the 6 year period 1985 to 1990. The rationale was to attempt to identify significant risk factors. 'Psychological autopsies' were carried out on material from the coroner's files. The results of the study suggest that suicide among the young in the ACT appears to be the result of a complex interplay of intrapersonal, interpersonal and social environmental factors.

Adolescent↗
PubMed1992

MCMI-II personality disorders in recent-onset bipolar disorders.

This study investigated the personality disorders of 21 recent-onset Bipolar Disorder patients using the revised Million Clinical Multiaxial Inventory (MCMI-II; Millon, 1987). Personality disorder assessments, conducted after patients' clinical symptoms had settled, indicated that 17 patients received at least one MCMI-II personality disorder diagnosis with a trend toward multiple diagnoses. Narcissistic, Antisocial, and Histrionic personality disorders were diagnosed most frequently and were the scales most elevated. Schizoid and Compulsive personality disorders were the scales least elevated. Diagnostic concordance between the MCMI-II and the Structured Interview for DSM-III Personality (SIDP; Pfohl, Stangl, & Zimmerman, 1983) was poor; the MCMI-II made more multiple diagnoses. Implications of the discrepancies between these instruments and suggestions for future research are discussed.

Adult↗
PubMed1992

Metabolism of 1,2-dibromoethane in the human fetal liver.

1. Toxicity of 1,2-dibromoethane requires bioactivation via glutathione S-transferase. Since this enzyme is undetectable in the fetus of several laboratory animal species during early gestation, in vitro studies were carried out with human fetal liver to assess potential fetotoxicity. 2. Glutathione S-transferase occurs abundantly in the human fetal liver cytosol and its titer is equal to or exceeds that found in adult human liver when estimated using 1-chloro-2,4-nitrobenzene as the second substrate. 3. Human fetal liver cytosolic glutathione S-transferase metabolized 1,2-dibromoethane with a high efficiency (mean +/- SD specific activity of 3.10 +/- 0.83 nmol/min/mg protein). This reaction was enzymatic in nature and the rate of conjugation was proportional to the concentration of reduced glutathione, 1,2-dibromoethane and the enzyme present in the reaction medium. 4. A significant bioactivation with a possibility of only limited detoxication via cytochrome P-450-dependent oxidation suggests that human fetus may be at greater risk from 1,2-dibromoethane toxicity than adult.

Biotransformation↗
PubMed1992

Nurse-managed primary care. Tapping the rural community power base.

Involving community members into plans and projects is especially salient in initiating and maintaining nurse-managed centers. Nowhere is community involvement more crucial than in establishing a nursing practice in an isolated rural setting. The authors share their first-hand experiences in community interaction in establishing the state-funded health center.

Ambulatory Care Facilities↗
PubMed1992

Pitfalls in the use of color-flow duplex ultrasound for screening of suspected arterial injuries in penetrated extremities.

We compared color-flow duplex ultrasonographic scanning (CFD) to arteriography in 67 patients who sustained 75 penetrating injuries to the extremities without obvious arterial injury. There were 72 negative and three (4.0%) positive CFD studies and no failed attempts. With arteriography as the "gold standard," CFD had a specificity of 99% and a sensitivity of 50%, positive and negative predictive values of 66% and 97%, and an accuracy of 96%. Small pseudoaneurysms were missed in an axillary and an aberrant radial artery, and a genicular artery pseudoaneurysm was misread as originating from the popliteal artery. Cautious interpretation of negative studies appears warranted, particularly in the axilla and in bifurcated arteries. Extremity arteries should be completely imaged to rule out aberrant anatomy. Questionable studies should be confirmed arteriographically. With these caveats, color-flow duplex scanning may be useful for screening extremities with penetrating injuries thought to harbor occult arterial injuries.

Angiography↗