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Biomedical subjects

J MacDonald

Publications and source records attributed to J MacDonald.

At least 55 records · Page 3Linked to original sources
PubMed1999

Evaluation of echocardiography in the management of elderly patients with heart failure.

OBJECTIVE: To determine the validity of a clinical diagnosis of systolic dysfunction in elderly patients with heart failure and assess the contribution of echocardiography to their management. SUBJECTS: 61 elderly patients with a diagnosis of heart failure in a geriatric assessment unit setting. METHODS: Prospective study determining sensitivity, specificity and predictive values of a clinical and radiological diagnosis compared with echocardiographic standard. Proposed management was compared before and after echocardiography. RESULTS: Clinical assessment was highly sensitive (93%) but lacked specificity (32%). Combining radiological and clinical diagnoses increased specificity to 58%. Echocardiography revised the lead cardiac diagnosis for 28% of patients and influenced patient management plans for 41%. CONCLUSION: For elderly patients with heart failure, echocardiography improves diagnostic accuracy and identifies those patients with potential to benefit from angiotensin-converting enzyme inhibitors.

Aged↗
PubMed1999

Naproxen does not alter indices of muscle damage in resistance-exercise trained men.

PURPOSE: Unaccustomed exercise is associated with an elevated plasma creatine kinase (CK), myofibrillar inflammation, and delayed onset muscle soreness (DOMS). Nonsteroidal antiinflammatory drugs (NSAID) may attenuate DOMS and indirect indices of inflammation in humans. METHODS: We studied the effects of an NSAID (naproxen sodium (500 mg, 2 times a day for 48 h)) taken before and after resistance exercise in eight healthy, moderately trained men in a randomized, double-blind trial. The exercise consisted of unilateral knee concentric/eccentric weight lifting with 6 sets x 10 repetitions at 80-85% of the 1 repetition maximal contraction. Muscle biopsies of each vastus lateralis (EX = exercised/REST = control) were taken 24 h after exercise for immunohistochemical staining of inflammatory cells (leukocyte common antigen). At 24 and 48 h postexercise, we also determined DOMS, plasma CK activity, and knee extensor muscle torque. RESULTS: Exercise resulted in an increased CK activity at +24 and +48 h (vs preexercise: P < 0.01), with no treatment effect. There were no treatment effects for any of the measured variables except for a return of voluntary knee extension torque to baseline by +48 h postexercise for NSAID treatment (P < 0.05). CONCLUSIONS: NSAID administration did not alter CK rise, muscle force deficit at 24 h postexercise, nor perceived muscle pain. In addition, the increased CK at 24 h postexercise was not associated with an acute myofibrillar inflammatory cell infiltrate in moderately trained men after resistance exercise.

Administration, Oral↗
PubMed1999

Performing CPR and holding hands. Interview by Barbara Sibbald.

A while back, ER nurse Janet MacDonald was caring for an elderly woman who had suffered a small stroke. The woman was scheduled for a CT scan the next morning, but when MacDonald told her she'd have to go home she became very upset and said she was scared. Very scared. "It was like a slap in the face," says MacDonald, who realized she wasn't caring for the patient's needs, just the hospital's. The nurse in charge agreed the woman needed to stay and they found a place for her.

Attitude of Health Personnel↗
PubMed1998

Immunoaffinity resin for purification of urinary leukotriene E4.

Urinary leukotriene E4 (LTE4) has been used as an index of total leukotriene synthesis. A wide variety of methods have been applied to measure LTE4 which has made direct comparison of urinary levels reported by different laboratories difficult. A new peptidoleukotriene immunoaffinity resin was utilized for urinary LTE4 purification in a method that is easy and inexpensive, utilizing commercially available reagents. This method is described and compared to other methods. LTE4 (50-250 pg/mL) added to a urine extract was quantitatively recovered using the immunoaffinity resin. Similarly, LTE4 (50-400 pg/mL) added to urine was recovered between 63 and 76%. The coefficient of variation of samples purified and quantified on the same or on different days ranged from 8-10%. There was a strong correlation (r2 = 0.95) between LTE4 concentrations determined after immunofiltration and immunoaffinity purification. Although there was a good correlation between urinary LTE4 levels measured without purification compared to after immunoaffinity purification, the high y-intercept of 179 indicates the presence of interfering substances in unpurified urine. Urinary LTE4 in normal healthy adults was 80 +/- 7 pg/mg creatinine, similar to that previously reported following HPLC or immunofiltration purification. Urinary LTE4 was also measured in healthy children (age 3-12) and found to be 103 +/- 9.

Adult↗
PubMed1998

A preliminary normative profile of mild traumatic brain injury diagnostic criteria.

This study investigated how mild traumatic brain injury (MTBI) diagnostic and related variables present in a large, nonreferred MTBI sample. Participants were 119 adults with MTBI, drawn from consecutive admissions to two hospital emergency wards. Within 3 weeks of injury, they were asked how the 1993 American Congress of Rehabilitation Medicine MTBI diagnostic criteria and related phenomena presented in their particular cases. Results showed that retrograde amnesia was not reported or was generally very brief; retrograde amnesia was not reported unless posttraumatic amnesia was also reported; and the median ratio of posttraumatic amnesia to retrograde amnesia duration, when both were reported, was 300:1. These and other data provide a preliminary normative profile of such MTBI phenomena, and can help with differential diagnosis of MTBI in individual cases.

Adult↗
PubMed1998

The significance of variations in the angular correction factor in in situ gamma spectrometry.

In situ gamma spectrometry is a powerful method of assessing radioactive contamination in soil. The most widely adopted calibration methodology relates the overall sensitivity of the detector system to the product of three calibration factors: (a) the flux at the detector per unit activity in the ground phi/S(A), (b) the detected count-rate per unit flux incident normally at the detector N0/phi and (c) a correction factor to take into account the angular non-uniformity in response of the detector (Nf/N0). The dependence of the latter factor on the activity distribution with soil depth is generally neglected despite the lack of published evidence to support this. By (i) modelling and (ii) use of published experimental profiles, this work examines the range of Nf/N0 values likely to be encountered in the field. It was found that the use of a fixed angular correction factor is justified given that the maximum errors in the derived activity concentration do not exceed 5% and are far outweighed by other uncertainties.

Calibration↗
PubMed1997

The choice of jet nebulizer, nebulizing flow, and addition of albuterol affects the output of tobramycin aerosols.

The use of inhaled antibiotics in the treatment of cystic fibrosis has become widespread despite controversy in the literature as to the appropriate dosing regimen and its effectiveness. This study compared two tobramycin (T) preparations (one with and one without the addition of albuterol) using two different jet nebulizers in order to determine if drug output would be affected. Using calibrated flows from a dry compressed gas source of 6 and 8 L/min as well as a specific compressor (Pulmo-Aide), the Hudson 1720 nebulizer was compared with the newer disposable Hudson 1730. The albuterol preparation used in this study was the Ventolin (albuterol) Respirator Solution (VRS). The nebulizers were charged with (1) 2 mL T (80 mg/2 mL) with 0.5 mL VRS (5 mg/mL) and normal saline solution to make the total nebulizer charge of 3 or 4 mL, or (2) 2 mL T and either 1 or 2 mL normal saline solution. A laser diffraction analyzer (Malvern 2600) was used to determine the aerosol particle size distribution. From the distribution, the respirable fraction, which is the fraction of aerosol that could enter and remain in the lungs, was calculated. For all solutions and each particular flow, the Hudson 1730 had a larger respirable fraction of T. The addition of VRS lowered the surface tension of the solution in the nebulizer and resulted in a greater output of T. This effect was most apparent for the 3-mL volume fills of the Hudson 1720. The greatest differences were between the 3-mL nebulizer charges of T using the Hudson 1720 driven by a flow of 6 L/min, which produced 8 mg of T in the respirable fraction, compared with 35 mg produced by the Hudson 1730 driven by a flow of 8 L/min. These results suggest that different nebulizers, different nebulizer solutions, and different techniques of nebulization may result in very different amounts of T aerosol output in the respirable fraction.

Administration, Inhalation↗
PubMed1996

Enhanced LTP in mice deficient in the AMPA receptor GluR2.

AMPA receptors (AMPARs) are not thought to be involved in the induction of long-term potentiation (LTP), but may be involved in its expression via second messenger pathways. However, one subunit of the AMPARs, GluR2, is also known to control Ca2+ influx. To test whether GluR2 plays any role in the induction of LTP, we generated mice that lacked this subunit. In GluR2 mutants, LTP in the CA1 region of hippocampal slices was markedly enhanced (2-fold) and nonsaturating, whereas neuronal excitability and paired-pulse facilitation were normal. The 9-fold increase in Ca2+ permeability, in response to kainate application, suggests one possible mechanism for enhanced LTP. Mutant mice exhibited increased mortality, and those surviving showed reduced exploration and impaired motor coordination. These results suggest an important role for GluR2 in regulating synaptic plasticity and behavior.

Animals↗
PubMed1996

The composition of glyphosate-tolerant soybean seeds is equivalent to that of conventional soybeans.

One important aspect of the safety assessment of genetically engineered crops destined for food and feed uses is the characterization of the consumed portion of the crop. One crop currently under development, glyphosate-tolerant soybeans (GTS), was modified by the addition of a glyphosate-tolerance gene to a commercial soybean cultivar. The composition of seeds and selected processing fractions from two GTS lines, designated 40-3-2 and 61-67-1, was compared with that of the parental soybean cultivar, A5403. Nutrients measured in the soybean seeds included macronutrients by proximate analyses (protein, fat, fiber, ash, carbohydrates), amino acids and fatty acids. Antinutrients measured in either the seed or toasted meal were trypsin inhibitor, lectins, isoflavones, stachyose, raffinose and phytate. Proximate analyses were also performed on batches of defatted toasted meal, defatted nontoasted meal, protein isolate, and protein concentrate prepared from GTS and control soybean seeds. In addition, refined, bleached, deodorized oil was made, along with crude soybean lecithin, from GTS and control soybeans. The analytical results demonstrated the GTS lines are equivalent to the parental, conventional soybean cultivar.

Amino Acids↗
PubMed1996

Learning opportunities for internal medicine residents: comparison of a tertiary care setting and a regional setting.

PURPOSE: To compare the learning opportunities for internal medicine residents in tertiary care and community hospital settings. METHOD: Two sites were studied: Victoria General Hospital, a teaching hospital affiliated with the Dalhousie University Faculty of Medicine, staffed by five general internists and serving Halifax County (population of 420,000); and South Shore Regional Hospital, serving the community of Bridgewater (with a catchment area of 50,000) and staffed by three general internists. All in- and outpatients seen in the two settings over a one-year period (1993) were described in accordance with the Canadian Institute for Health Information's major clinical categories, as well as a case mixture recommended as providing appropriate learning experiences for internal medicine clerks. Over a one-month period (August 1993), consecutive patients were interviewed, completing a health status questionnaire, the Medical Outcome Study Short Form 36 (SF-36). RESULTS: Data were collected from the records of 2,763 patients, and the SF-36 questionnaire was administered to 406 patients. The data indicate that the settings were relatively similar except that there was more case variety in the tertiary care setting, and that more patients with cardiovascular disease and no patient with acquired immune deficiency syndrome were seen in the regional setting. Quality-of-life scores showed similarities to norms in the United States and United Kingdom, except that the ambulatory patients in the regional setting had rather lower scores. CONCLUSION: Overall, the patients' problems in the regional and tertiary care settings offered similar learning opportunities.

Aged↗
PubMed1996

Evaluation of surfactant treatment strategies after prolonged graft storage in lung transplantation.

We have previously documented alterations in endogenous surfactant after lung transplantation and improved graft function in some dogs after instillation of bovine lipid extract surfactant (bLES) into the recipient. To determine the effect of bLES delivery method and timing of treatment on physiologic response and surfactant recovery, 21 canine left lung grafts were divided into four groups: (1) Treatment of the donor for 3 h with aerosolized bLES prior to graft storage (Donor Aerosol); (2) Treatment of the recipient with instilled bLES immediately after transplantation (Recipient Instilled); (3) No bLES treatment (Control); and (4) Aerosolized bLES in donors and instilled bLES in recipients (Combined Therapy). Aerosolized bLES was labeled with [3H]-dipalmitoylphosphatidylcholine (DPPC) and instilled bLES with [14C]-DPPC. Grafts were stored for 36 h, transplanted and reperfused for 6 h. The native right and transplanted left lungs were then lavaged and protein yield, surfactant aggregates, and bLES recovery were measured. After 6 h of reperfusion, PO2/FlO2 ratio was significantly better after Combined Therapy (372 +/- 52 mm Hg) than in the Recipient Instilled (117 +/- 47 mm Hg) and Control groups (87 +/- 26 mm Hg), with intermediate values in Donor Aerosol dogs (232 +/- 64 mm Hg). The recovery of donor aerosolized bLES from transplanted lungs was increased in dogs given Combined Therapy versus Donor Aerosol treatment alone (p = 0.03). Furthermore, with Combined Therapy there was an increased percentage of instilled bLES recovered from transplanted lungs compared with the Recipient Instilled group. We conclude that surfactant treatment strategies influence physiologic response and bLES recovery after prolonged lung preservation. Treatment of lung donors with exogenous surfactant prior to graft storage was associated with less severe lung injury. Combined donor and recipient bLES therapy resulted in a superior physiologic response during reperfusion in this model.

Aerosols↗
PubMed1995

The incidence of hyperemesis gravidarum is increased among Pacific Islanders living in Wellington.

AIMS: To compare the incidence of hyperemesis gravidarum among Pacific Islanders living in Wellington with nonPacific Islanders and to investigate some properties of the disorder. METHODS: Data were collected on all first time admissions to Wellington Women's Hospital for hyperemesis gravidarum over a 5-year period. Women were classified as having severe hyperemesis gravidarum if abnormalities of serum electrolytes and liver function tests results were present and as less severe if these abnormalities were absent. Almost all women had ketonuria. Mantel-Haenszel odds ratios, chi 2 analysis and Fisher's 2-tailed exact test were used for statistical analysis. RESULTS: The proportion of hyperemesis gravidarum patients who were Pacific Islanders was significantly increased when compared to their proportion in a control group (p < 0.01). The difference remained significant when the hyperemesis patients were divided into less and more severe. Abnormal thyroid function test results were more common among Pacific Island patients than among nonPacific Island patients. This difference was significant (p < 0.01) only in the less severe group. CONCLUSION: The incidence of hyperemesis gravidarum is significantly increased among Pacific Island women (especially Samoans) living in Wellington and is often associated with abnormalities of thyroid function test results.

Female↗
PubMed1995

Imaging strategies in the first 12 months after reduction of developmental dislocation of the hip.

We have reviewed the records of 32 infants whose developmental dislocation of the hip (DDH) was treated by reduction and immobilization in a plaster cast. We examined 50 CT scans from 22 patients. The postreduction radiological studies led to a change of cast in 10 patients and, in five of them, the subluxation shown on CT scan was not seen in an earlier radiograph. Where reduction has been undertaken at the time of arthrography or in an older child, a plain radiograph may be adequate to confirm the position in the cast. In an infant, CT scans give superior information, have acceptable risks, and should be used in association with radiation protection measures.

Arthrography↗