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Biomedical subjects

D Scott

Publications and source records attributed to D Scott.

At least 145 records · Page 8Linked to original sources
PubMed1997

Drug calculation competencies of graduate nurses.

This study describes the analysis of the mathematical ability of 220 registered nurses (RNs) from six Victorian universities who applied for a graduate year program at St Vincent's Hospital, Melbourne. Each applicant completed a drug calculation competency test (DCCT) which required them to calculate 11 drug dosages commonly performed by RNs in clinical practice. The results revealed that 58 percent (n = 127) of the 220 applicants were not able to accurately calculate all 11 drug dosages. The results also demonstrated significant differences between applicants from respective universities. The findings suggest that there are fundamental problems with the mathematical competencies of this group of newly graduated nurses. The results may also support the assertion that the educational preparation of these nurses at the undergraduate level could be enhanced in some universities and does not appear to adequately prepare nurses to perform basic drug calculations which are frequently required in the acute setting.

Clinical Competence↗
PubMed1997

Iron supplementation moderates but does not cure the Belgrade anemia.

Belgrade rats inherit microcytic, hypochromic anemia as an autosomal recessive trait (gene symbol b). Erythrocytes and tissue are iron deficient in the face of elevated TIBC (total iron binding capacity) and percent iron saturation; iron injections increased the number of erythrocytes but their appearance remained abnormal. We have investigated iron supplements to improve husbandry of b/b rats and to learn more about the underlying defect and its tissue distribution. Weekly i.m. (intramuscular) injections of iron-dextran (Imferon at 30 mg kg-1) improved the anemia but did not alter the red cell morphology. Certain diets also improved the health of b/b rats when compared to standard rat chows by the criteria of weight, survival to adulthood, hematology and reproduction. The critical nutritional factor turned out to be iron bioavailability, with ferrous iron added to the diet improving the health of Belgrade rats without affecting the underlying erythroid defect. Tissue iron measurements after dietary or parenteral supplementation confirmed the iron deficient status of untreated b/b rats and established that dietary ferrous iron partially relieved this deficiency, with injections leading to greater amounts of tissue iron. Serum iron and TIBC were also found to be elevated in untreated b/b rats, with dietary supplementation decreasing but not eliminating the elevation in TIBC. These studies indicate that iron supplements can improve the health of b/b rats without altering the underlying defect and also suggest that the mutation could alter iron uptake in the GI (gastrointestinal) tract.

Anemia, Hypochromic↗
PubMed1997

Absence of mutations in the ATM gene in breast cancer patients with severe responses to radiotherapy.

The effectiveness of cancer radiotherapy is compromised by the small proportion (approximately 5%) of patients who sustain severe normal tissue damage after standard radiotherapy treatments. Predictive tests are required to identify these highly radiosensitive cases. Patients with the rare, recessively inherited, cancer-prone syndrome ataxia-telangiectasia (A-T) sustain extremely severe normal tissue necrosis after radiotherapy and their cultured cells are also highly radiosensitive. Clinically normal carriers (heterozygotes) of the A-T gene have an increased risk of breast cancer, account for approximately 4% of all breast cancer cases and show a modest increase in cellular radiosensitivity in vitro. It has been suggested that a substantial proportion of highly radiosensitive (HR) breast cancer patients may be A-T heterozygotes, and that screening for mutations in the A-T gene could be used as a predictive test. We have tested this hypothesis in a group of cancer patients who showed adverse reactions to radiotherapy. Sixteen HR breast cancer patients showing mainly acute reactions (and seven HR patients with other cancers) were tested for ATM mutations using the restriction endonuclease fingerprinting assay. No mutations typical of those found in obligate A-T heterozygotes were detected. If the estimate that 4% of breast cancer cases are A-T gene carriers is correct, then ATM mutations do not confer clinical radiosensitivity. These early results suggest that screening for ATM mutations in cancer patients may not be of value in predicting adverse reactions.

Ataxia Telangiectasia Mutated Proteins↗
PubMed1997

G2 chromosomal radiosensitivity in fibroblasts of ataxia-telangiectasia heterozygotes and a Li-Fraumeni syndrome patient with radioresistant cells.

PURPOSE: To investigate whether the good discrimination we previously observed between ataxia-telangiectasia (A-T) heterozygotes and normal donors for induction of chromosome aberrations by X-rays in G2 lymphocytes is also seen in G2 fibroblasts. Also to investigate the G2 radiosensitivity of a patient with the cancer-prone Li-Fraumeni syndrome (LFS) whose fibroblasts are resistant to the lethal effects of radiation. MATERIALS AND METHODS: Fibroblasts were exposed to 0.5 Gy X-rays and harvested for metaphase analysis 90 min later. RESULTS: Four A-T heterozygote cell strains were all more sensitive than seven normal controls. The LFS strain with a germline TP53 mutation was twice as sensitive as the mean control value. CONCLUSIONS: Although chromosomal, radiosensitivity is seen in A-T heterozygotes and LFS cells, the former are radiosensitive and the latter radioresistant to cell killing. Repair defects may predominate in A-T heterozygotes, inadequate genome surveillance in LFS cells.

Ataxia Telangiectasia↗
PubMed1997

Visualization of an extracellular mucoid layer of Treponema denticola ATCC 35405 and surface sugar lectin analysis of some Treponema species.

Slime layers and capsules are common amongst medically relevant bacteria. We herein report that Treponema denticola, which has been associated with periodontitis, synthesizes or acquires an extracellular polysaccharide layer that we have observed through electron microscopy using the polysaccharide-specific dye Alcian blue and phosphotungstate. We have also visualized this extracellular layer by dark-field microscopy of Alcian blue-stained spirochete cells. A representative strain of each of the oral spirochete species T. denticola, Treponema vincentii and Treponema socranskii were differentiated by concanavalin A, phaseolus, lotus A and arachis lectins in a microtiter plate immunoassay for the detection of surface sugars.

Bacterial Capsules↗
PubMed1997

The researcher's personal responses as a source of insight in the research process.

Drawing on accounts of the author's personal responses while undertaking a qualitative study on the norms governing the relationship between nurses and mothers, it is argued that such responses, rather than being seen as a source of bias, have the potential to be a source of insight and interpretation in the research. This paper tells the 'inside' story of previously published research that was 'sanitized' by the omission of any reference to the researcher's subjective responses. The recognition of such researcher responses has implications for how research is supervised and presented.

Anthropology, Cultural↗
PubMed1997

Effect of diets varying in nitrogen or phosphorus content on indicators of bone growth in lambs.

Growing lambs were fed diets low in nitrogen and phosphorus (LNLP), low in nitrogen and high in phosphorus (LNHP), high in nitrogen and low in phosphorus (HNLP) or high in nitrogen and phosphorus (HNHP) and the effects on bone growth and on blood and urinary bone marker levels or excretion rates were monitored. Plasma calcium concentrations were higher, and phosphorus concentrations lower, in lambs fed the low phosphorus diets but there were no differences in plasma 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) concentrations. Lambs fed both low phosphorus diets (LNLP and HNLP) had lower plasma osteocalcin and higher bone-specific alkaline phosphatase concentrations than those fed the high phosphorus diets. Urinary pyridinoline and deoxypyridinoline excretion were also affected by treatment, with their rates of excretion being highest in lambs fed the diet low in both nitrogen and phosphorus (LNLP). Lambs fed the low phosphorus diets were lighter in weight at slaughter and had lighter bones that were less well mineralized than those fed the high phosphorus diets. Reducing the nitrogen content of the diet appeared to have little effect on bone composition. These results suggest that bone markers that have proved useful in the diagnosis and treatment of bone disease are sensitive to variation in nutrient supply and may prove useful in early detection of nutrient deficiencies that affect bone growth.

Animals↗
PubMed1997

Glycosaminoglycan depletion greatly raises the hydraulic permeability of rabbit joint synovial lining.

The hydraulic resistance of the synovial lining of a joint is important for retention of intraarticular lubricant. The resistance has been attributed to synovial interstitial glycosaminoglycans. This was tested by depletion of hyaluronan and chondroitin sulphates from synovium in five rabbit knees in vivo under anaesthesia, using testicular hyaluronidase. The enzyme raised synovial permeability to fluid 5- to 7-fold-substantially more, in fact, than predicted by a recent model. The results prove that hyaluronan and/or chondroitin sulphate are important sources of hydraulic resistance in synovium.

Animals↗
PubMed1997

Intestinal tolerability of nitroxybutyl-flurbiprofen in rats.

BACKGROUND: Nitric oxide derivatives of non-steroidal anti-inflammatory drugs (NSAIDs) are thought to be much less ulcerogenic than their parent compounds. AIM: To compare the effect and potency of flurbiprofen and nitroxybutyl-flurbiprofen to uncouple mitochondrial oxidative phosphorylation (an early pathogenic event in NSAID enteropathy), increase intestinal permeability (transitional stage), and cause macroscopic small intestinal damage. METHODS: In vitro uncoupling potency was assessed using isolated coupled rat liver mitochondria and in vivo by electron microscopy of rat small intestinal mucosa (two hours after the drugs). A dose-response study with flurbiprofen (single doses of 5, 10, 20, and 40 mg/kg) and equimolar doses of nitroxybutyl-flurbiprofen was performed; assessing their effect on intestinal permeability (at 18-20 hours), with 51Cr EDTA, and the number of pointed (< 5 mm) and longitudinal (> 5 mm) small intestinal ulcers at 24 hours. RESULTS: Flurbiprofen, but not nitroxybutyl-flurbiprofen, stimulated coupled respiration in vitro. Both drugs, however, uncoupled in vivo; in the case of nitroxybutyl-flurbiprofen possibly because hydrolysis of its ester bond released free flurbiprofen. Intestinal permeability was uniformly and equally increased with both drugs compared with controls. The number of small intestinal ulcers, pointed and longitudinal, was significantly reduced with nitroxybutyl-flurbiprofen apart from the number of longitudinal ulcers with the highest dose. CONCLUSIONS: These studies show that nitroxybutyl-flurbiprofen is associated with significantly less macroscopic damage in the small intestine than flurbiprofen but was associated with mitochondrial damage in vivo and caused similar increases in permeability of the small intestine, suggesting that its beneficial effect is on the later pathogenic stages of the damage.

Animals↗
PubMed1997

Mitochondrial damage: a possible mechanism of the "topical" phase of NSAID induced injury to the rat intestine.

BACKGROUND: The "topical" effect of non-steroidal anti-inflammatory drugs (NSAIDs) seems to be an important cause of NSAID induced gastrointestinal damage. AIM: To examine the possible mechanism of the "topical" phase of damage in the small intestine. METHODS: Electron microscopy and subcellular organelle marker enzyme studies were done in rat small intestine after oral administration of indomethacin (doses varied between 5 and 30 mg/kg). The effect of conventional and non-acidic NSAIDs on rat liver mitochondrial respiration was measured in vitro in a Clarke-type oxygen electrode. RESULTS: The subcellular organelle marker enzymes showed mitochondrial and brush border involvement within an hour of indomethacin administration. Electron microscopy showed dose dependent mitochondrial changes following indomethacin administration consistent with uncoupling of oxidative phosphorylation (or inhibition of electron transport) which were indistinguishable from those seen with the uncoupler dinitrophenol. Parenteral indomethacin caused similar changes, but not in rats with ligated bile ducts. A range of NSAIDs, but not paracetamol or non-acidic NSAIDs which have a favourable gastrointestinal tolerability profile, uncoupled oxidative phosphorylation in vitro at micromolar concentrations and inhibited respiration at higher concentrations. In vivo studies with nabumetone and aspirin further suggested that uncoupling or inhibition of electron transport underlies the "topical" phase of NSAID induced damage. CONCLUSION: Collectively, these studies suggest that NSAID induced changes in mitochondrial energy production may be an important component of the "topical" phase of damage induction.

Acetaminophen↗
PubMed1997

The male-specific histocompatibility antigen, H-Y: a history of transplantation, immune response genes, sex determination and expression cloning.

H-Y was originally discovered as a transplantation antigen. In vivo primary skin graft responses to H-Y are controlled by immune response (Ir) genes mapping to the MHC. In vitro T cell responses to H-Y are controlled by MHC class I and II Ir genes, which-respectively, restrict CD8 and CD4 T cells: These can be isolated as T cell clones in vitro. T cell receptor (TCR) transgenic mice have been made from the rearranged TCR genes of several of these, of which that specific for H-Y/Db is the best studied. Non-MHC Ir genes also contribute to the control of in vitro CTL responses to H-Y. The Hya/HYA gene(s) encoding H-Y antigen have been mapped using translocations, mutations, and deletions to Yq in humans and to the short arm of the Y chromosome in mice, where they lie in the deletion defined by the Sxrb mutation between Zfy-1 and Zfy-2. Hya/HYA has been separated from the testis-determining gene, Sry/SRY, in both humans and mice and in humans the azoospermia factor AZF has been separated from HYA. In mice transfection of cosmids and cDNAs mapping to the Sxrb deletion has identified two genes encoding H-Y peptide epitopes. Two such epitopes, H-Y/K(k) and H-Y/D(k), are encoded within different exons of Smcy and a third, H-Y/D(b), by a novel gene, Uty. Peptide elution approaches have isolated a human H-Y epitope, H-Y/HLA-B7, and identified it as a product of SMCY. Each of the Hya genes in mice is ubiquitously expressed but of unknown function. Their X chromosome homologues do not undergo X inactivation.

Animals↗
PubMed1997

Effect of hypokalemia on the abundance of HK alpha 1 and HK alpha 2 protein in the rat kidney.

An H(+)-K(+)-adenosinetriphosphatase (H(+)-K(+)-ATPase) contributes to potassium reabsorption by the collecting ducts of the rat kidney. mRNAs for two isoforms of the H(+)-K(+)-ATPase, HK alpha 1 and HK alpha 2, have been found in the rat kidney. To evaluate whether the HK alpha 1 and HK alpha 2 proteins are present in the rat kidney, microsomes enriched in HK alpha 1 or HK alpha 2 were isolated using the MiniMac magnetic separation system with antibodies directed against either HK alpha 1 (HK 12.18) or HK alpha 2 (AS 31.7). Immunoblots of rat kidney microsomal protein isolated with HK 12.18 revealed a band approximately 94 kDa in size that comigrated with the G1 fraction of the stomach. Immunoblots of rat kidney microsomal protein isolated with AS 31.7 revealed a band slightly greater than 94 kDa that comigrated with a band obtained from rat colonic microsomal protein. To examine the effect of perturbations in potassium metabolism, the abundance of the HK alpha 1 and HK alpha 2 isoforms was compared in rats fed a normal or potassium-deficient diet. A low-potassium diet increased the abundance of HK alpha 2, whereas that of HK alpha 1 was not altered. These data suggest that HK alpha 2 might be the isoform responsible for potassium conservation by the kidney.

Animals↗
PubMed1997

Joy-riding among British youth.

The behavioural and legal aspects of the problematic and repetitive criminal behaviour of aggravated vehicle taking or "joyriding" are reviewed as context for a study in Great Britain of data from 20 males imprisoned for joy-riding and/or vehicle theft for gain, 10 habitual joyriders who were members of a youth club established to counter the problem, 10 imprisoned house-breakers, and 10 males with no criminal convictions. No specific ethnographic, motivational, or personality differences between joy-riders and those involved in other crimes of theft were found, although there was evidence for the notion of joyriding developing into car theft for pure financial gain.

Adolescent↗
PubMed1997

Experimental Results with the Multi-Linkª Stent in a Porcine Model.

OBJECTIVES: The purpose of this study was to assess the delivery characteristics and the vascular response to placement of the Multi-Linkª stent in normal porcine coronary arteries. BACKGROUND: The Multi-Link stent is a balloon expandable stainless steel stent with an interconnected corrugated ring structure designed to provide a high degree of compressive resistance while preserving longitudinal flexibility. The placement characteristics and vascular response to this stent in normal porcine coronary arteries has not been characterized. METHODS: We tested the delivery characteristics and vascular response to the Multi-Link stent in 19 normolipemic miniature swine. Quantitative coronary angiography was used to define stent performance characteristics such as stent expansion and recoil. Histologic assessment of the stented arteries was used to evaluate the acute and chronic vascular response to stent placement. RESULTS: Thirty-five of thirty-five stents (100%) were successfully implanted in the left anterior descending (n = 14), left circumflex (n = 8) or right (n = 13) coronary arteries of nineteen swine. The baseline angiographic mean lumen diameter of the stented coronary segment was 3.41 +/- 0.32 mm and increased to 3.53 +/- 0.33 mm (p < 0.001) after stent placement. The balloon inflated stent diameter was 3.61 +/- 0.36 mm with minimal recoil to a final minimal lumen diameter of 3.53 +/- 0.33 mm after implant (p = 0.001). Linear regression analysis revealed that the percent stent recoil had a significant positive correlation with the stent to artery ratio or the degree of stent over-sizing (r = 0.67; p < 0.0001). Angiographic and histologic follow-up at 72 hours (n = 9), 14 days (n = 12) and 56 days (n = 12) demonstrated that all stents were patent without evidence of migration, intraluminal filling defect or side-branch occlusion. On histology, there was rare evidence of stent-induced deep arterial wall injury such as rupture of the internal elastic lamina and medial laceration. There was no significant difference in the mean injury score observed on day 3 (0.23 +/- 0.22), 14 (0.35 +/- 0.28) or 56 (0.36 +/- 0.27) after implant (p = 0.27). On day 3, the mean thrombus thickness overlying the stent wires was 70 +/- 98µ. The mean neointimal area was similar at 14 and 56 days after implant (1.63 +/- 1.25 mm2 versus 1.78 +/- 0.68 mm2, p = 0.54). CONCLUSIONS: The MULTI-LINK stent easily tracked the coronary arteries and deployed reliably in this experimental model. The multiple interconnected ring geometry of the stent provides adequate compressive resistance, longitudinal flexibility and uniform coverage of the arterial wall throughout the length of the endoprothesis. The stent has acceptable blood and tissue biocompatibility in normal porcine coronary arteries. Oversizing this stent (>10 percent) may have a theoretical disadvantage resulting in a proportionally higher degree of stent recoil. The results of clinical trials will determine if the design features of the Multi-Link stent favorably impact on procedural outcome or long-term patency.

Journal Article↗
PubMed1997

Avoiding diarrhea after subtotal colectomy with primary anastomosis in the treatment of colon cancer.

BACKGROUND: Subtotal colectomy has been criticized as causing increased frequency of stool passage, thus adding to the patients' morbidity. We review our experience with subtotal colectomy and determine the factors affecting postoperative diarrhea. STUDY DESIGN: One hundred thirty-six patients with colon cancer were treated by primary subtotal colectomy. Of these, 30 percent underwent an emergency resection; 15 percent, semi-emergency resection; and 55 percent, elective subtotal colectomy. There were 29 complications and 3 deaths. RESULTS: The incidence of complications was higher when the operation was carried out on an emergency or semi-emergency basis. In assessing the patients' increased postoperative stool frequency, there was no difference between the groups; but, the length of the remaining colon and the resected terminal ileum had a significant effect on postoperative diarrhea. If less than 10 cm of terminal ileum is resected and more than 10 cm of colon is left above the peritoneal reflection, there is a marked decrease in the incidence of diarrhea after subtotal colectomy. CONCLUSIONS: Subtotal colectomy is an acceptable treatment for left colonic carcinoma, electively as well as in emergency situations. Postoperative diarrhea can be minimized by attention to the length of small bowel and sigmoid that are resected.

Adult↗