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Biomedical subjects

D Banks

Publications and source records attributed to D Banks.

At least 37 records · Page 2Linked to original sources
PubMed1999

The outcome of asthma related to workplace irritant exposures: a comparison of irritant-induced asthma and irritant aggravation of asthma.

STUDY OBJECTIVES: (1) To characterize workers' compensation claims accepted on the basis of new-onset asthma associated with accidental high respiratory irritant exposure at work; (2) to compare the frequency, characteristics, and outcomes in this group of workers to workers who were compensated for an exacerbation of preexisting asthma associated with accidental high respiratory irritant exposure at work. DESIGN: A retrospective review was performed of 469 asthma claims accepted by the Ontario Workers' Compensation Board (WCB) between 1984 and 1988. Among these, claims attributed to an accidental high respiratory irritant exposure at work were classified into two groups: one group with reported preexisting asthma prior to the exposure (accidental aggravation of asthma [AAA]) and another group with no previous history of asthma (irritant-induced asthma [IIA]). RESULTS: Of the 469 claims, 89 subjects (19%) had symptoms related to accidental high respiratory irritant exposure in the workplace; of these, 68 subjects (76%) had AAA, 12 subjects (13%) had IIA, and 9 subjects (10%) had possible IIA but were excluded from the analysis because of insufficient data. Those with IIA had a longer duration of work-attributed symptoms (mean, 219 +/- 208 days) than the subjects with AAA (mean, 32 +/- 38 days; p < 0.001). Nine subjects (75%) with IIA were no longer in the same work environment, while 47 subjects in the AAA group (71%) were still in the same work environment (p < 0.001). The most common triggering agent for subjects with IIA was an isocyanate spill; for those with AAA, the most common triggering agent was paint. CONCLUSIONS: The WCB-accepted claims related to accidental, high respiratory irritant exposure at work are more commonly assigned to the category of AAA than to IIA. IIA patients in this claimant group had a longer mean duration of work-attributed respiratory symptoms, perhaps due to a need for a larger (and thus less common) irritant exposure to induce asthma in previously normal subjects.

Adult↗
PubMed1998

The chemistry of Norwegian groundwaters: I. The distribution of radon, major and minor elements in 1604 crystalline bedrock groundwaters.

A quality-controlled hydrogeochemical dataset of 1604 groundwater samples from Norwegian crystalline bedrock aquifers has been obtained and subject to analyses of radon (scintillation counting), major and minor elements (ion chromatography and ICP-AES), pH and alkalinity. Cumulative probability curves may be constructed to assess the risk of given parameters violating drinking water norms. Parameters such as radon and fluoride show clear lithological correlation, occurring at high concentrations in granites and low concentrations in anorthosites. Other parameters exhibit a lower degree of correlation with aquifer geochemistry (e.g. pH, major ions) and are likely to be governed by more universal thermodynamic equilibria (the calcium carbonate system) and kinetic factors. On a national basis 13.9% of the bedrock groundwaters exceed the recommended action level for radon, while 16.1% exceed the drinking water norm for fluoride. Considering pH, sodium, radon and fluoride together, 29.9% of all wells violate drinking water maximum concentrations for one or more of these parameters.

Calcium↗
PubMed1998

The chemistry of Norwegian groundwaters: II. The chemistry of 72 groundwaters from Quaternary sedimentary aquifers.

Seventy-two samples of groundwater derived from Norwegian Quaternary (largely glaciofluvial or glacial) aquifers were analysed for a wide range of major and minor hydrochemical parameters. The waters exhibit a relatively uncomplex evolution from Na-Cl dominated, immature waters (which reflect marine salts in precipitation) to Ca-HCO3 dominated waters via calcite dissolution. The median pH of these waters is 7.37, in contrast to similar waters from crystalline bedrock aquifers with a median pH of 8.07. The water samples provide little evidence of significant acidification or sulphatisation of groundwaters by 'acid rain'. In fact, a positive correlation emerges between non-marine sulphate and alkalinity/pH, suggesting dominantly lithological sources for non-marine sulphate. No groundwaters from Quaternary deposits exceed maximum recommended concentrations for Rn, F- and Na, while 10% fall outside the required pH range. This again contrasts with bedrock aquifers where 30% of waters are non-compliant with respect to one or more of these parameters.

Acid Rain↗
PubMed1998

The comparative hydrochemistry of two granitic island aquifers: the Isles of Scilly, UK and the Hvaler Islands, Norway.

A comparative study is presented of granitic groundwaters from the Hvaler Islands, south-eastern Norway (11 samples) and the Scilly Islands, south-western England (10 samples). The islands display similar bulk lithologies (peraluminous S-type, U/Th-enriched granites) and land use, but differing glaciation and hence weathering histories. The groundwater of both groups bears a strong marine signature, although the Hvaler Islands display less marine influence and a greater degree of water-rock interaction. The most interesting hydrochemical dissimilarities concern the health related trace elements Rn, U and F. These display median (and maximum) values of 2510 Bq/l (8520 Bq/l), 15 micrograms/l (170 micrograms/l) and 3.3 mg/l (4.4 mg/l), respectively, for Hvaler, compared with 140 Bq/l (200 Bq/l), 1.5 micrograms/l (4 micrograms/l) and 0.1 mg/l (0.27 mg/l) for Scilly. Commonly employed drinking water limits for these parameters are 500 Bq/l (Norwegian action level), 20 micrograms/l (Canadian limit) and 1.5 mg/l. The differences in groundwater contents of these elements between Hvaler and Scilly may be ascribed to: (i) differing trace element compositions of the granites and fracture mineralisations; (ii) radically differing recent weathering histories; and (iii) hydrodynamic factors.

Chemical Phenomena↗
PubMed1997

Protective effects of antioxidants against benomyl-induced lipid peroxidation and glutathione depletion in rats.

The present in vivo study was designed to examine the effects of the antioxidants, N,N-diphenyl-p-phenylenediamine (DPPD) and a 21-aminosteroid (U74389G), on methyl 1-(butylcarbamoyl)-2-benzimidazole-carbamate (benomyl)-induced lipid peroxidation and glutathione depletion in rats. Male Sprague Dawley rats weighing 200 250 g were used in this study and were fasted for 8 12 h before treatment. Benomyl (200 mg/kg/day in olive oil) was administered orally for 7 days to groups of untreated rats and to rats pretreated with two doses (15 mg/kg) of either DPPD or U74389G. Benomyl treatment resulted in a significant increase in serum hydroperoxides and a significant decline in hepatic reduced glutathione (GSH) levels. These results indicate that benomyl induces lipid peroxidation and glutathione depletion in rats. Benomyl-induced lipid peroxidation was blocked by DPPD pretreatment but was not significantly altered by U74389G. However, both antioxidants, DPPD and U74389G, were able to inhibit glutathione depletion induced by benomyl. The present findings indicate that the in vivo toxicity of benomyl may be associated with oxidative stress to cellular membranes and that some degree of protection against this toxicity could be afforded by antioxidants.

Animals↗
PubMed1997

Intraoperative hetastarch infusion impairs hemostasis after cardiac operations.

BACKGROUND: An outbreak of excessive bleeding after cardiac operations occurred at our institution when 5% albumin was in short supply and hetastarch became the preferred intraoperative colloid. As hetastarch may impair coagulation, we investigated the effects of its intraoperative administration on post-cardiac surgical hemostasis. METHODS: Indices of postoperative hemostasis were analyzed in 189 consecutive patients undergoing coronary artery bypass grafting. Three groups were compared: one group (n = 68) received a mean of 796 mL of hetastarch only in the operating room (a few minutes after cessation of cardiopulmonary bypass), another group (n = 59) received a mean of 856 mL postoperatively only, and a third group (n = 62) received no hetastarch. RESULTS: Compared with the other two groups, those patients administered hetastarch intraoperatively exhibited significant reductions in hematocrit and platelet count, a significant prolongation in the prothrombin time, and significant increases in both blood loss and hemostatic drug requirement. Also identified were obvious trends toward a greater transfusion requirement and reexploration rate for bleeding in the latter group. CONCLUSIONS: Hetastarch infusion just after weaning from cardiopulmonary bypass produces a clinically important impairment in post-cardiac surgical hemostasis. Intraoperative use of this agent during heart operations should be avoided until the safe timing of its administration is clarified.

Blood Loss, Surgical↗
PubMed1997

Intravenous phenylephrine preconditioning of cardiac grafts from non-heart-beating donors.

BACKGROUND: Hypoxia and warm ischemia produce severe injury to cardiac grafts harvested from non-heartbeating donors. To potentially improve recovery of such grafts, we studied the effects of intravenous phenylephrine preconditioning. METHODS: Thirty-seven blood-perfused rabbit hearts were studied. Three groups of non-heart-beating donors underwent intravenous treatment with phenylephrine at 12.5 (n = 8), 25 (n = 7), or 50 microg/kg (n = 7) before initiation of apnea. Non-heart-beating controls (n = 8) received saline vehicle. Hypoxic cardiac arrest occurred after 6 to 12 minutes of apnea, followed by 20 minutes of warm in vivo ischemia. A 45-minute period of ex vivo reperfusion ensued. Nonischemic controls (n = 7) were perfused without antecedent hypoxia or ischemia. RESULTS: Phenylephrine 25 microg/kg significantly delayed the onset of hypoxic cardiac arrest compared with saline controls (9.6 +/- 0.5 versus 7.7 +/- 0.4 minutes; p = 0.00001), yet improved recovery of left ventricular developed pressure compared with saline controls (57.1 +/- 5.3 versus 41.0 +/- 3.4 mm Hg; p = 0.04). Phenylephrine 25 microg/kg also yielded a trend toward less myocardial edema than saline vehicle (p = 0.09). CONCLUSIONS: Functional recovery of nonbeating cardiac grafts is improved by preconditioning. We provide evidence that the myocardium can be preconditioned with phenylephrine against hypoxic cardiac arrest.

Analysis of Variance↗
PubMed1997

Is vertical vein ligation necessary in repair of total anomalous pulmonary venous connection?

BACKGROUND: In the repair of total anomalous venous connection, vertical vein ligation is recommended to eliminate left-to-right shunting. However, the small left heart chambers may not always tolerate the immediate increase in blood flow after combined repair and vein ligation. METHODS: A retrospective review of 23 infants and children undergoing correction of total anomalous pulmonary venous connection was undertaken to determine whether vertical vein ligation is a necessary component of successful surgical repair. In 14 patients this vein was ligated, whereas in 9 it was left patent. Six patients who underwent ligation and 5 who did not had pulmonary venous obstruction before operation. RESULTS: The operative mortality rate was 36% (5 of 14 patients) for the ligated group compared with 0% (0 of 9 patients) for the nonligated group (p = 0.06). All deaths occurred in patients with preoperative obstruction and a low mean left atrial pressure, and four of the deaths were directly attributable to left heart failure. Follow-up echocardiography in patients in whom the vertical vein was not ligated revealed adequate cardiac function and no residual left-to-right flow through the previously patent venous conduit. CONCLUSION: Vertical vein ligation during the repair of total anomalous pulmonary venous connection is not routinely necessary and actually may be undesirable in patients with preoperative obstruction, in whom the left heart chambers are particularly small.

Cardiac Surgical Procedures↗
PubMed1997

Sodium nitroprusside exacerbates myocardial ischemia-reperfusion injury.

BACKGROUND: The role of nitric oxide in myocardial ischemia-reperfusion is controversial. Although many studies claim that nitric oxide ameliorates reperfusion injury, others suggest that it exacerbates such injury, possibly through peroxynitrite production. These discordant results may be attributable to a dose-dependent phenomenon. METHODS: Isolated rabbit hearts sustained sequential periods of blood perfusion (20 minutes), warm ischemia (30 minutes), and reperfusion (20 minutes). During reperfusion, four groups underwent intracoronary infusion of saline solution (n = 6), or the nitric oxide donor sodium nitroprusside (100 nm/min [SNP100, n = 6], 1 nmol x L(-1)/min(-1) [SNP1, n = 6], or 0.01 nmol x L(-1) x min(-1) [SNP0.01]). Left ventricular-developed pressure and oxygen consumption were measured after preischemic perfusion and reperfusion. Levels of myocardial nitrotyrosine, a marker for peroxynitrite, were measured after reperfusion with an immunoradiochemical assay. RESULTS: Postischemic-developed pressure and myocardial oxygen consumption were significantly higher in the saline group than all nitroprusside-reperfused groups (p < 0.01 for both parameters). However, there were no differences in either parameter between SNP100, SNP1, or SNP0.01. Nitrotyrosine levels were similar among the four groups (p = 0.43). CONCLUSIONS: Nitroprusside exacerbates myocardial ischemia-reperfusion injury over a wide range of doses, although the mechanism does not appear to be mediated by peroxynitrite.

Animals↗
PubMed1997

Student nurses perceptions of their interpersonal skills: a re-examination of Burnard and Morrison's findings.

Heron's six category intervention analysis is a component of many counselling courses and is used extensively by teachers of interpersonal skills within nursing curricula. The popularity of this framework has generated a number of studies which have attempted to offer empirical support for the theory. The aim of this study was to re-evaluate some of these findings. Utilising an earlier research instrument, a set of findings are offered and comparisons made with previous work. Our findings suggest that student nurses perceive themselves to be most skilled in the use of supportive, prescriptive and cathartic interventions and least skilled in the use of informative, catalytic and confronting interventions. A discussion of the new findings and their implications is offered.

Education, Nursing↗
PubMed1997

Outcome determinants for isocyanate induced occupational asthma among compensation claimants.

OBJECTIVES: To compare the outcome of occupational asthma (OA) induced by isocyanates in Ontario (where a surveillance programme for exposed workers has been in place for over 15 years), with the outcome of OA induced by other work agents. METHODS: Compensated OA claims during the period 1984-88 in Ontario were retrospectively reviewed in a standardised way. RESULTS: 136/235 compensated claims were attributed to isocyanates. Compared with other causes of OA, those attributed to isocyanates had a shorter latent period before onset (5.9 v 7.9 years, P < 0.05), shorter duration of symptoms before diagnosis (2.0 v 3.0 years, P < 0.05), and less associated atopy (43% v 58%, P < 0.05). Outcome at a mean of 1.9 years after initial assessment was significantly better in those with OA induced by isocyanates; 73% cleared or improved v 56% with other causes of OA (P < 0.05). Ten subjects with OA induced by isocyanates stayed at the same work; none cleared and four had worsened at follow up. A better outcome in OA induced by isocyanates was associated with early diagnosis (P < 0.05), and early removal from isocyanates after the onset of asthma. CONCLUSIONS: The outcome in the group with OA induced by isocyanates is similar to previous follow up studies. However, it is better than the outcome in our comparison group with OA due to other causes, perhaps because of earlier diagnosis in the group with OA induced by isocyanates. This may be attributable to the medical surveillance of workers exposed to isocyanates in Ontario, either directly from the surveillance assessments, or indirectly by increasing awareness of the condition.

Adult↗
PubMed1997

Validation of the advanced dynamic anthropomorphic manikin (ADAM) database: horizontal sled test.

As the U.S. Air Force (USAF) continues to introduce advanced technology to make its planes more dynamic, it is becoming increasingly more difficult to adequately test the systems to ensure pilot safety. A cost effective solution to this problem is the use of computer modeling to augment testing. The accuracy of such computer modeling depends on the validity of the analytical formulation, and the correctness of the database characterizing the systems being modeled. One such database is for the large Advanced Dynamic Anthropomorphic Manikin (ADAM); a human surrogate developed by the USAF for high speed ejection testing. The database is used in the Articulated Total Body (ATB) computer model utilized by the Armstrong Laboratories to predict human body dynamics during aircraft crashes and emergency escapes. The large ADAM database, and the parameters from a horizontal sled test were used in an ATB sled simulation. The results of the ATB simulation are compared with actual sled test data. These results include head, chest, and pelvis accelerations; neck and lumbar loads; and elbow, knee, hip and shoulder angular motion. The comparisons are the basis for validating the ADAM database for future predictive simulations.

Acceleration↗
PubMed1996

Controlled reperfusion of cardiac grafts from non-heart-beating donors.

BACKGROUND: Hearts harvested from non-heart-beating donors sustain severe injury during procurement and implantation, mandating interventions to preserve their function. We tested the hypothesis that limiting oxygen delivery during initial reperfusion of such hearts would reduce free-radical injury. METHODS: Rabbits sustained hypoxic arrest after ventilatory withdrawal, followed by 20 minutes of in vivo ischemia. Hearts were excised and reperfused with blood under conditions of high arterial oxygen tension (PaO2) (approximately 400 mm Hg), low PaO2 (approximately 60 to 70 mm Hg), high pressure (80 mm Hg), and low pressure (40 mm Hg), with or without free-radical scavenger infusion. Non-heart-beating donor groups were defined by the initial reperfusion conditions: high PaO2/ high pressure (n = 8), low PaO2/high pressure (n = 7), high PaO2/low pressure (n = 8), low PaO2/low pressure (n = 7), and high PaO2/high pressure/free-radical scavenger infusion (n = 7). RESULTS: After 45 minutes of reperfusion, low PaO2/ high pressure and high PaO2/low pressure had a significantly higher left ventricular developed pressure (63.6 +/- 5.6 and 63.1 +/- 5.6 mm Hg, respectively) than high PaO2/high pressure (40.9 +/- 4.5 mm Hg; p < 0.0000001 versus both). However, high PaO2/high pressure/free-radical scavenger infusion displayed only a trend toward improved ventricular recovery compared with high PaO2/ high pressure. CONCLUSIONS: Initially reperfusing nonbeating cardiac grafts at low PaO2 or low pressure improves recovery, but may involve mechanisms other than decreased free-radical injury.

Animals↗
PubMed1996

Analysis of the T-cell receptor repertoire of human T-cell leukemia virus type 1 (HTLV-1) Tax-specific CD8+ cytotoxic T lymphocytes from patients with HTLV-1-associated disease: evidence for oligoclonal expansion.

Human T-cell leukemia virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a chronic, progressive neurological disease characterized by marked degeneration of the spinal cord and the presence of antibodies against HTLV-1. Patients with HAM/TSP, but not asymptomatic carriers, show very high precursor frequencies of HTLV-1-specific CD8+ T cells in peripheral blood and cerebrospinal fluid, suggestive of a role of these T cells in the pathogenesis of the disease. In HLA-A2+ HAM/TSP patients, HTLV-1-specific T cells were demonstrated to be directed predominantly against one HTLV-1 epitope, namely, Tax11-19. In the present study, we analyzed HLA-A2-restricted HTLV-1 Tax11-19-specific cytotoxic T cells from three patients with HAM/TSP. An analysis of the T-cell receptor (TCR) repertoire of these cells revealed an absence of restricted variable (V) region usage. Different combinations of TCR V alpha and V beta genes were utilized between, but also within, the individual patients for the recognition of Tax11-19. Sequence analysis of the TCR showed evidence for an oligoclonal expansion of few founder T cells in each patient. Apparent structural motifs were identified for the CDR3 regions of the TCR beta chains. One T-cell clone could be detected within the same patient over a period of 3 years. We suggest that these in vivo clonally expanded T cells might play a role in the pathogenesis of HAM/TSP and provide information on HTLV-1-specific TCR which may elucidate the nature of the T cells that infiltrate the central nervous system in HAM/TSP patients.

Amino Acid Sequence↗
PubMed1996

Dosimetric evaluation of copper-64 in copper-67-2IT-BAT-Lym-1 for radioimmunotherapy.

UNLABELLED: Copper-67 (67Cu) is an attractive radionuclide for radioimmuno-therapy because of its favorable physical and biologic characteristics. Current supplies of 67Cu, however, contain as much as 60% of 64Cu at the time of delivery. Scatter photons from 64Cu enter the 67Cu energy window, affecting image resolution and counting accuracy. The radiation dose to tissue is also altered. METHODS: A line source and a small vial source of 67Cu containing varying amounts of 64Cu were used to evaluate the impact of 64Cu on image resolution and activity quantitation, respectively. Identical pharmacokinetics for 67Cu and 64Cu was assumed, and the radiation dosimetry of 64Cu was assessed using quantitative imaging data for 67Cu because the amount of 64Cu could be calculated for any time after 67Cu production. MIRD formalism was used to estimate the therapeutic index, defined as the ratio of radiation dose to tumor divided by the radiation dose to bone marrow. RESULTS: As the amount of 64Cu increased, the full width at tenth maximum of the line spread function increased, although there was no significant change in full width at half maximum. The number of scatter counts from 64Cu increased as the amount of 64Cu or the size of the source region of interest increased. When 64Cu was 25% of the total activity, less than 10% of the total 67Cu photopeak counts detected with a scintillation camera were attributable to 64Cu. Although the tumor radiation dose per unit of activity (cGy/GBq) from 67Cu was five times greater than that from 64Cu, the marrow dose (CGy/GBq) from 67Cu was only three times greater than that from 64Cu. Therefore, the therapeutic index was diminished by the presence of 64Cu. When 64Cu radioimpurity was less than 25% of the total activity, there was less than a 10% decrease in the therapeutic index. CONCLUSION: The shorter physical half-life of 64Cu relative to that of 67Cu and slower uptake and longer retention of antibody by tumor than by marrow result in a lower therapeutic index for 64Cu. The 25% radioimpurity of 64Cu causes less than 10% deviation in activity quantitation and diminution in the therapeutic index. The change in therapeutic index is predictable over time and can be used to determine the optimal time for radiopharmaceutical administration.

Bone Marrow↗
PubMed1995

Long-term safety of statin-fibrate combination treatment in the management of hypercholesterolaemia in patients with coronary artery disease.

OBJECTIVE: To evaluate the long-term safety profile of treatment with a statin-fibrate combination in a cohort of patients with documented coronary artery disease. DESIGN: Retrospective cohort analytical study. SETTING: District general hospital. PATIENTS: 102 (81 male and 21 female) hypercholesterolaemic (total cholesterol concentration > 6.5 mmol/l) patients with documented coronary artery disease and who had been treated with a statin-fibrate combination for over 1 year. Coronary artery disease was confirmed by angiography in 93 patients and by a positive (Bruce protocol) exercise test in the remainder. Fifty eight patients had a history of previous coronary bypass graft surgery. INTERVENTIONS: Twice daily lipid lowering treatment was given, with the fibrate administered in the morning (either bezafibrate 400 mg (n = 101) or fenofibrate 200 mg (n = 1)) and the statin in the evening (either simvastatin 10 mg (n = 23), 20 mg (n = 72), or 40 mg (n = 2) or pravastatin 10 mg (n = 1) or 20 mg (n = 4)). Treatment continued for 1 (n = 9), 2 (n = 58), or 3 (n = 35) years. MAIN OUTCOME MEASURES: Selected laboratory variables (total cholesterol concentration and liver (aspartate transaminase (AST)) and muscle enzyme (creatine kinase (CK)) activities) and documented symptomatology. RESULTS: A mean (SD) total cholesterol concentration of 5.2 (0.8) mmol/l was achieved after combined treatment for 1 year which was maintained at annual follow up. Over a maximum 3 year follow up no patient reported myalgic symptoms and none had a measured CK activity > 10 times above nomal. Four men on a simvastatin-bezafibrate combination had a CK activity rise to less than three times normal. Fourteen patients with a negative history of alcohol excess (consumption < 21 units/week) had borderline raised AST values. CONCLUSIONS: Statin-fibrate combination treatment for up to 3 years in a cohort of patients with coronary artery disease was not associated with serious disturbances in biochemical markers of muscle or liver function.

Adult↗
PubMed1994

An experimental evaluation of an incentive program to reduce serum cholesterol levels among health fair participants.

OBJECTIVE: To evaluate the impact of a health fair and incentive program on the reduction of serum cholesterol levels among participants. DESIGN: Pretest-posttest control group design, with a 6-month delay between pretest and posttest screenings. SETTING: Health fair program for employees of a large midwestern school district. PARTICIPANTS: Volunteer sample among persons with serum cholesterol levels above 5.17 mmol/L (200 mg/dL). Participants were randomly assigned to experimental (N = 29) and comparison groups (N = 34). INTERVENTION: The intervention consisted of four components: a health fair, health risk information, announcement of follow-up screening, and an incentive program. The incentive program consisted of five $100 cash prizes for reducing serum cholesterol levels by 20% or below 5.17 mmol/L (200 mg/dL). The comparison group received only the first three components. MAIN OUTCOME MEASURE: Serum cholesterol levels were measured by a venipuncture, nonfasting, chemical analysis process. RESULTS: The experimental group showed a 13.2% reduction in serum cholesterol levels, and the comparison group exhibited an 11.3% reduction (P < .05). CONCLUSIONS: A health fair, consisting of information on the level of risk and how to reduce risk, and announcement of follow-up screening and incentives can reduce the risk for cardiovascular disease.

Adult↗