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Biomedical subjects

R Chow

Publications and source records attributed to R Chow.

At least 19 recordsLinked to original sources
PubMed2006

Accuracy of healthcare worker recall and medical record review for identifying infectious exposures to hospitalized patients.

OBJECTIVE: To determine the validity of using healthcare worker (HCW) recall of patient interactions and medical record review for contact tracing in a critical care setting. DESIGN: Trained observers recorded the interactions of nurses, respiratory therapists, and service assistants with study patients in a medical-surgical intensive care unit. These observers' records were used as the reference standard to test the criterion validity of using HCW recall data or medical record review data to identify exposure characteristics. We assessed the effects of previous quarantine of the HCW (because of possible exposure) and the availability of patients' medical records for use as memory aids on the accuracy of HCW recall. SETTING: A 10-bed medical-surgical intensive care unit at Mount Sinai Hospital in Toronto, Ontario. PATIENTS: Thirty-six HCWs observed caring for 16 patients, for a total of 55 healthcare worker shifts. RESULTS: Recall accuracy was better among HCWs who were provided with patient medical records as memory aids (P<.01). However, HCWs tended to overestimate exposures when they used patient medical records as memory aids. For 6 of 26 procedures or care activities, this tendency to overestimate was statistically significant (P<.05). Most HCWs with true exposures were identified by means of this technique, despite the overestimations. Documentation of the activities of the 4 service assistants could not be found in any of the patients' medical records. Similarly, the interactions between 6 (19%) of 32 other patient-HCW pairs were not recorded in patients' medical records. CONCLUSIONS: Data collected from follow-up interviews with HCWs in which they are provided with patient medical records as memory aids should be adequate for contact tracing and for determining exposure histories. Neither follow-up interviews nor medical record review alone provide sufficient data for these purposes.

Disease Transmission, Infectious↗
PubMed2006

A survey of physician's attitudes regarding management of severe group A streptococcal infections.

Intravenous immunoglobulins (IVIG) use in the management of streptococcal toxic shock syndrome remains highly controversial. To evaluate the current management of severe group A streptococcal infections and the feasibility of a randomized controlled trial comparing immunoglobulins versus placebo for streptococcal toxic shock syndrome and/or necrotizing fasciitis, a 32-question mail and web-based survey of Canadian infectious disease specialists was conducted between December 2003 and February 2004. Overall, 172 respondents (90.5%) recommended immunoglobulins as adjunctive treatment of streptococcal toxic shock compared to 67 (35.3%) for fasciitis without toxic shock and 93 (48.9%) for invasive group A streptococcal infections with hypotension. A considerable proportion of respondents agreed that a randomized clinical trial in streptococcal toxic shock (70.1%, 131/187) and necrotizing fasciitis without toxic shock (88.2%, 162/186) would be ethical. From these, a great majority would be willing to enroll patients in a trial comparing IVIG to placebo for streptococcal toxic shock (125/131, 95.4%) and necrotizing fasciitis without shock (152/162, 93.8%). These initial results clearly demonstrate ambivalence in the utilization of intravenous immunoglobulins (IVIG) in invasive group A streptococcal infections in Canada and emphasize the need for further clinical data on immunoglobulin use in streptococcal toxic shock syndrome. They also demonstrate that, although the majority of physicians recommend immunoglobulins, there is important variability between physician recommendations with regard to the indications of use, dose, and time of administration.

Canada↗
PubMed2005

A study on the primary and secondary nucleation of ice by power ultrasound.

Several different investigations have been carried out to study the primary and secondary nucleation of ice by sonocrystallisation. Firstly, the primary nucleation of discrete ice crystals in a supercooled sucrose solution has been observed. For increasing concentrations of sucrose solutions from 0 to 45 wt%, the nucleation temperature consistently occurs at a higher nucleation temperature in the presence of ultrasound. The nucleation temperature also increases as the power output and duty cycle of a commercial ultrasonic horn are increased. Snap shot images of the bubble clouds obtained from the ultrasonic horn also show that the number of bubbles appears to increase as the ultrasonic output is increased. This suggests that the nucleation of ice is related to the power output and number of cavitation bubbles. The effect of a single bubble on the sonocrystallisation of ice is discussed. High-speed movies (1120 fps) have shown that the crystallisation appears to occur in the immediate vicinity of the single bubble. In most cases, many crystals are observed and it is not known whether a single ice crystal is being fragmented by the bubble or whether many crystals are being initiated. The bubble appears to undergo a dancing regime, frequently splitting and rejoining and also emitting some small microbubbles. A study on the secondary nucleation of ice in sucrose solutions has been carried out using a unique ultrasonic cold stage device. Images taken using a microscope system show that the pre-existing ice dendrite crystals can be broken up into smaller fragments by an ultrasonic field. Cavitation bubbles appear to be important during the fragmentation process, possibly melting any ice crystals in their path. Flow patterns around cavitation bubbles have also been observed, and these may be responsible for the fragmentation of ice crystals.

Crystallization↗
PubMed2000

Longitudinal evaluation of supervised versus unsupervised exercise programs for the treatment of osteoporosis.

The efficacy of an exercise program was investigated in a study of 89 post-menopausal women with osteoporosis over a 5-year follow-up period. The study attempted to examine and compare potential differences in bone mineral density (BMD), incidence of fracture, and loss of height, between a group of patients (n = 42) who attended the supervised exercise program in the hospital, and a group (n = 47) who exercised at home. Habitual physical activity, as estimated using the Harvard Alumni Questionnaire, and a Physical Activity Index were combined to obtain an estimate of overall weekly caloric expenditure over the 5-year period. The exercise program involved weight-bearing aerobic activities of moderate intensity, and muscle strengthening exercise using free weights. The mean percentage change for the lumbar BMD was + 4.4% in the hospital group and +3.4% in the home group while for the femoral neck BMD was + 1.1% in the hospital group and -0.9% in the home group. There was a significant reduction in the number of fractures and no significant loss of height over the 5-year follow-up period for both groups. As the correlation between BMD and weekly caloric expenditure of the subjects was not significant, no conclusion can be drawn as to the minimum level of caloric expenditure necessary in order to retard bone loss. It was concluded that for the post-menopausal women with osteoporosis who participated in the program it was possible to stabilize their height and the BMD of the lumbar site, and to reduce fractures over the 5-year study period regardless if they exercised in a supervised or in an unsupervised setting.

Aged↗
PubMed1999

Rapid detection of mecA in methicillin resistant Staphylococcus aureus using cycling probe technology.

A novel method has been developed for the detection of the mecA gene, that confers the principle mechanism of methicillin resistance in staphylococci. Cycling Probe Technology (CPT) is a rapid, simple, isothermal method for the detection of specific target sequences. CPT utilizes a unique chimeric DNA-RNA-DNA probe sequence that provides an RNase H sensitive scissile link when hybridized to a complementary target DNA sequence. In the presence of target DNA, the cycling reaction converts full-length chimeric probe into cleaved probe fragments, which accumulate and are quantified. A cycling probe designed for detection of a specific sequence within the mecA gene was used to develop a culture confirmation assay for methicillin resistant Staphylococcus aureus. The CPT assay was used to screen 238 S. aureus isolates and the results were in complete agreement with detection of the mecA gene by polymerase chain reaction (PCR). Detection of mecA should be considered the gold standard for determining methicillin resistance in S. aureus. This study demonstrates the feasibility of using CPT to meet this need.

Bacterial Proteins↗
PubMed1996

Prevention and management of osteoporosis: consensus statements from the Scientific Advisory Board of the Osteoporosis Society of Canada. 5. Physical activity as therapy for osteoporosis.

OBJECTIVE: To examine exercise as a therapy for people with osteoporosis. OPTIONS: Immobilization, standing low-load and high-load physical activities. OUTCOMES: Risk of injury, quality of life, risk of falls and fractures, strength and posture and pain management. EVIDENCE: Relevant epidemiologic studies, clinical trials and reviews were examined, including the large-scale FICSIT trial in the United States, a prospective 4-year study of women enrolled in an exercise program in Toronto and the large-scale Study of Osteoporotic Fractures. VALUES: Minimizing risk of injury and increasing quality of life were given a high value. BENEFITS, HARMS, AND COSTS: Moderate physical activity in people with osteoporosis can reduce the risk of falls and fractures, decrease pain and improve fitness and overall quality of life. It may also stimulate bone gain and decrease bone loss. Its positive effects are an adjunct to other interventions, such as hormonal therapy. It may give patients the confidence to resume regular activity and can provide social interaction and support. During exercise programs, proper nutrition is necessary to prevent excessive weight loss and impaired immune function resulting from inadequate protein, vitamin and mineral intake. RECOMMENDATIONS: Immobilization should be avoided if possible in anyone with osteoporosis or at increased risk for osteoporosis. Regular, moderate physical activity is recommended for those with osteoporosis. Elderly people should be assessed for risk of falling to identify those in greatest need of an exercise program. Community group exercise programs are beneficial. Younger people with osteoporosis also need exercise that will preserve or improve bone mass, muscular strength, endurance and cardiovascular fitness. Weight loss as a result of physical activity should be avoided and adequate intake of protein, vitamins and minerals assured. Because the benefits of physical activity are independent of the effect of other therapies, physical activity is an essential adjunct to appropriate nutrition and other therapies. VALIDATION: These recommendations were developed by the Scientific Advisory Board of the Osteoporosis Society of Canada at its 1995 Consensus Conference. They are in agreement with the position taken on osteoporosis and exercise by the United States Center for Disease Control and Prevention and the American College of Sports Medicine. SPONSORS: Sponsors of the 1995 conference included the Dairy Farmers of Canada, Eli Lilly Canada, Inc., Hoffmann-La Roche Canada Ltd., Merck Frosst Canada Inc. and Procter & Gamble Pharmaceuticals Canada Inc.

Accidental Falls↗
PubMed1994

Transforming growth factor-beta 1 lowers the CD14 content of monocytes.

Marked elevation of transforming growth factor-beta 1 (TGF-beta 1) has been demonstrated clinically following injury and in sepsis. While alterations in the monocyte binding site (CD14) for the lipopolysaccharide (LPS)-lipopolysaccharide binding protein (LBP) complex have been noted with exposure to LPS, immune complexes, gamma-interferon, and IL-4, it is not known whether TGF-beta 1 can alter CD14 expression. To study the effect of TGF-beta 1 on monocyte CD14 expression, human leukocytes were isolated from healthy donors with discontinuous gradient centrifugation and incubated at 37 degrees C for 2 and 24 hr with increasing doses of purified human platelet TGF-beta 1. Monocytes were immunofluorescently stained with monoclonal antibodies recognizing CD14 and CD16. The cells were analyzed by flow cytometry. At 2 hr, 50 ng/ml TGF-beta 1 significantly lowered CD14 expression (51%, P = 0.043). At 24 hr, there was no significant difference between cells stimulated by TGF-beta 1 and control cells. To confirm that TGF-beta 1 was active at 24 hr, we examined levels of CD16. CD16 expression was increased by 10 ng/ml of TGF-beta 1. These observations suggest that high physiologic concentrations of TGF-beta 1 cause early monocyte suppression of CD14. Thus, CD14 may be marker for the transition of monocytes to macrophages and TGF-beta 1 may be responsible for the down-regulation of CD14 expression observed in monocytes obtained from septic patients.

Antigens, CD↗
PubMed1993

Evaluation of a program for rehabilitation of osteoporotic patients (PRO): 4-year follow-up. The Bone and Mineral Group of the University of Toronto.

The value of a program for the rehabilitation of osteoporotic patients (PRO) was assessed from a 4-year follow up of 139 patients referred to the program over its initial 2 years of operation. The program consisted of educational seminars, social activities and regular exercise supervision. Patients had annual clinical assessments, and bone mass measurements by neutron activation analysis (reported as CaBI). Fitness was assessed by performance on a treadmill (reported in terms of VO2max, ml/kg/min). Seventy-eight of the 139 patients remained in the program over the 4-year follow-up. This unusually high level of commitment to the program is indicative of the psychological value that patients have derived from it. The effect of the program on the osteoporosis process was inconclusive. Group 2, the 37 patients who obtained the greatest improvement in fitness (VO2max > 6 ml/kg/min), had a significantly greater reduction in back pain than did group 1, the 36 with less significant improvement (VO2max < or = 6 ml/kg/min). The bone mass and incidence of vertebral fractures on entry into the program were not significantly different between the two groups. Group 2 had on average a greater increase in bone mass over the 4 years; mean increases in CaBI, (+/- SD) were 0.09 +/- 0.09 and 0.05 +/- 0.10 for groups 2 and 1 respectively. Group 2 had on average fewer new vertebral fractures (0.08 +/- 0.36 and 0.28 +/- 0.75 for groups 2 and 1 respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

The functional properties of hemoglobin modified with mellitic dianhydride: possible applications as a blood substitute.

Human oxyhemoglobin reacts with mellitic dianhydride to produce a modified protein which shows a reduced oxygen affinity over a wide pH range, a reduced but significant cooperativity, a reduced Bohr effect and no response to the allosteric effectors: chloride, clofibric acid or inositol hexaphosphate. The amount of crosslinking in the modified hemoglobin is approximately 22% suggesting promise as a blood substitute. Reaction of deoxyhemoglobin with mellitic dianhydride produces a modified protein with reduced response to clofibric acid and a decrease in oxygen affinity in the presence of inositol hexaphosphate.

Blood Substitutes↗
PubMed1993

Medication use patterns in HIV-positive patients.

Patients with HIV infection or AIDS often receive several medications for treatment or prevention of their primary disease and/or associated complications. The objective of this study was to document patterns of drug use in an HIV-positive, outpatient population. Data were collected via one-on-one interviews with 26 HIV-positive patients; prescription and non-prescription drug use, adverse drug reactions and drug allergies were recorded. Anti-retroviral therapy was received by over 90 % of the patients. Over 90% of patients were on anti-infective agents, commonly cotrimoxazole or dapsone, while 27% received acyclovir. At least 70% of patients used three or more prescription medications concurrently. Every patient reported self-medicating with at least one over-the-counter (OTC) product and over half used three or more OTC products concurrently. Adverse reactions, mainly attributable to zidovudine, were reported by over 80% of patients. Non-compliance was a common drug-related issue; over 70% of patients omitted drug doses. In conclusion, the use of multiple medications in the ambulatory HIV-positive patients presents the health care team with potential drug-related problems that may ultimately affect the efficacy and toxicity of therapy. Thus pharmacists may play an active role in the provision of direct care to these patients.

Adult↗
PubMed1990

Fluoride treatment of postmenopausal osteoporosis: age, renal function, and other clinical factors in the osteogenic response.

We report on 61 women with postmenopausal osteoporosis who were treated with either plain sodium fluoride (NaF) capsules or enteric-coated NaF tablets for 4 years, in whom possible therapeutic and toxic effects were monitored. In these patients there was a mean increase in axial bone mineral mass, assessed by neutron activation analysis, of 26.2% +/- 2.4% (SEM) during the 4 years. This corresponds to a decrease in the bone deficit (compared with reference values) of 48.6%. The response was linear over 4 years. The main predictors of the osteogenic response were bone fluoride (r = 0.52, p less than 0.01), serum fluoride (r = 0.50, p less than 0.01), and age (0.39, p less than 0.01). Patients over 65 years of age achieved higher bone fluoride (F) levels and a significantly greater increase in bone mineral than younger patients (32.8 vs. 17.9%, p less than 0.01), associated with an age-related decline in renal function; serum fluoride was significantly and negatively correlated to creatinine clearance (r = -0.52, p less than 0.01). Although the effect of NaF on fracture rate could not be assessed in this uncontrolled study, the major factors associated with the occurrence of new vertebral fractures were the number of vertebral fractures and the bone mineral mass at the beginning of therapy. There was no correlation between vertebral fracture rate and serum or bone fluoride or other parameters of the osteogenic response, but patients who did not experience new vertebral fractures achieved a normal bone mineral content sooner than those who had new fractures during therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Prevention and rehabilitation of osteoporosis program: exercise and osteoporosis.

Osteoporosis is a common crippling bone disease affecting post-menopausal and elderly women. It results in fractures, spinal deformity and chronic pain leading to decreased mobility and functional disability. A preventive program in Toronto, described in this article, aims to prevent bone loss and maximise the functional capacity of osteoporotic patients through a program with educational, social and exercise components. Evaluation of the program, also reported here, showed that 80 per cent of patients complied with the requirements of the exercise program and that those who exercised reported improvement in general well being, stamina, mobility and pain tolerance. The exercise group also showed a significant improvement in VO 2 max (p less than 0.001) and bone mass (p less than 0.02) after one year of exercise. None of the patients developed fracture as a direct result of the exercise. The exercise prescribed for osteoporosis is safe and beneficial. The program is a social success.

Aged↗
PubMed1988

The effect of verapamil, diltiazem and nifedipine on baroreceptor reflexes.

Heart rate in nifedipine treated patients tends to be higher than in those treated with verapamil or diltiazem. This may be due, among other causes, to a differential action on cardiac baroreflexes. As conclusions of previous studies were controversial, we decided to study the effect of verapamil, diltiazem and nifedipine on baroreflex sensitivity. After 3-5 week treatment, heart rate response to various doses of i.v. phenylephrine and sodium nitroprusside was recorded in conscious rats. The slope of the regression line relating change of heart rate to change in blood pressure, was depressed in verapamil treated rats compared to that in control, diltiazem or nifedipine treated rats (p less than 0.0001). The role of the autonomic nervous system in modulation of baroreflexes was investigated by pretreatment of the animals with propranolol or atropine. The results were compatible with the hypothesis that verapamil depresses adrenergic nerve activity and this may contribute to decreased, vasodilation-induced baroreceptor reflexes.

Animals↗
PubMed1987

Effect of two randomised exercise programmes on bone mass of healthy postmenopausal women.

The effect of two structured exercise programmes on the bone mass of 48 healthy postmenopausal white women aged 50-62 was studied after one year. Volunteers were randomised to group 1 (control), group 2 (aerobic exercise), or group 3 (aerobic and strengthening exercises). Before and after the training programme each subject had evaluations of bone mass (determined by neutron activation analysis and expressed as calcium bone index) and maximum oxygen uptake attained on a multistage exercise treadmill test. After one year both exercise groups had higher levels of fitness and greater bone mass than controls. Mean values (2 SEM) for changes in the calcium bone index were -0.011 (0.037), 0.039 (0.035), and 0.066 (0.036) for groups 1, 2, and 3, respectively. Analysis of variance on the observed data and analysis of covariance adjusting changes to the initial mean value for the whole group showed significant differences between each exercise group and the controls but no difference between the exercise groups themselves. Both exercise groups showed a significant improvement in maximum oxygen uptake. This study suggests that exercise may modify bone loss in healthy postmenopausal women.

Bone and Bones↗