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Biomedical subjects

K Cook

Publications and source records attributed to K Cook.

At least 19 recordsLinked to original sources
PubMed2003

Lumbar multifidus muscle size does not differ whether ultrasound imaging is performed in prone or side lying.

This methodological study examined the influence of body position when measuring multifidus muscle size using real-time ultrasound imaging. Previous studies examined multifidus with the subject prone but people with certain conditions cannot be studied in this position, so side lying was investigated as an alternative posture. In 20 normal females (aged 19-45 years), the cross-sectional area (CSA) of lumbar multifidus was measured at the level of the fifth lumbar vertebra (L5) on both the right and left sides, with the subject in prone and in side lying. Multifidus CSA was highly correlated between the two positions on both the right (r=0.90) and left (r=0.91) sides. Paired t-tests found no significant differences between the measurements made in the two scanning postures (right P=0.77; left P=0.16). Bland and Altman plots showed good agreement between the two positions, with no systematic difference. These findings demonstrate that measurements of lumbar multifidus at L5 can be made in either prone or side lying and a valid comparison of the results obtained in both positions can be made.

Adult↗
PubMed2002

Recovery of resources for advanced life support space applications: effect of retention time on biodegradation of two crop residues in a fed-batch, continuous stirred tank reactor.

Bioreactor retention time is a key process variable that will influence costs that are relevant to long distance space travel or long duration space habitation. However. little is known about the effects of this parameter on the microbiological treatment options that are being proposed for Advanced Life Support (ALS) systems. Two bioreactor studies were designed to examine this variable. In the first one, six retention times ranging from 1.3 to 21.3 days--were run in duplicate, 81 working-volume continuous stirred tank reactors (CSTR) that were fed ALS wheat residues. Ash-free dry weight loss, carbon mineralization, soluble TOC reduction, changes in fiber content (cellulose, hemicellulose, and lignin), bacterial numbers, and mineral recoveries were monitored. At short retention times--1.33 days--biodegradation was poor (total: 16-20%, cellulose - 12%, hemicellulose - 28%) but soluble TOC was decreased by 75-80% and recovery of major crop inorganic nutrients was adequate, except for phosphorus. A high proportion of the total bacteria (ca. 83%) was actively respiring. At the longest retention time tested, 21.3 days, biodegradation was good (total: 55-60%, cellulose ca. 70%, hemicellulose - ca. 55%) and soluble TOC was decreased by 80%. Recovery of major nutrients, except phosphorus, remained adequate. A very low proportion of total bacteria was actively respiring (ca. 16%). The second bioreactor study used potato residue to determine if even shorter retention times could be used (range 0.25-2.0 days). Although overall biodegradation deteriorated, the degradation of soluble TOC continued to be ca. 75%. We conclude that if the goal of ALS bioprocessing is maximal degradation of crop residues, including cellulose, then retention times of 10 days or longer will be needed. If the goal is to provide inorganic nutrients with the smallest volume/weight bioreactor possible, then a retention time of 1 day (or less) is sufficient.

Aerobiosis↗
PubMed2002

Sensitivity and accuracy of routine antenatal ultrasound screening for isolated facial clefts.

Facial clefts, as a group, represent one of the most frequently occurring congenital abnormalities detectable on prenatal mid-trimester scan. It has been estimated that, at term, approximately 1 in 1000 infants will be diagnosed with an isolated facial cleft. The aim of this study was to determine the sensitivity and accuracy of routine second trimester ultrasound screening for facial clefts. This was a prospective study of isolated fetal facial clefts, detected at 18-23 weeks gestation, in a routine obstetric population. The antenatal detection rate of facial clefts was derived by comparing the number of cases identified antenatally with the number of neonatal cleft surgeries performed in this centre, for the local population only. The accuracy of antenatal diagnosis of facial clefts was calculated by matching data from the ultrasound database to birth registries and neonatal cleft surgeries performed in this centre, including the referred cases. During the study period, 17,551 women underwent a routine anomaly scan at 18-23 weeks of gestation. A total of 30 babies underwent surgery for isolated facial cleft in this centre during that period. There were no false positive diagnoses of facial clefts, and in five cases (all unilateral), the antenatal diagnosis was found to be inaccurate. 12 babies were from the local population, of which 9 had an antenatal diagnosis of facial cleft, giving a sensitivity of 75%. The current study highlights the effectiveness of antenatal screening for facial clefts. Additionally, it highlights the appropriate terminology that needs to be used in the accurate description of antenatally diagnosed facial clefts.

Cleft Lip↗
PubMed2001

Efficacy of the ketogenic diet in focal versus generalized seizures.

Most reports of the ketogenic diet have focused on its efficacy for generalized seizures. Few data are available regarding its effect on focal seizures. We retrospectively studied patients (mean = 7.5 years of age) with medically intractable epilepsy treated by the ketogenic diet. The predominant seizure types in each patient were classified as generalized (100 patients) or focal (34 patients) based on ictal electroencephalograms (EEGs) or seizure semiology and interictal EEG. A seizure reduction of more than 50% compared with baseline was seen in nine patients (27%) with focal seizures and 46 patients (46%) with generalized seizures at 3 months, in 10 patients (30%) with focal seizures and 46 patients (46%) with generalized seizures at 6 months, and in eight patients (24%) with focal seizures and 42 patients (42%) with generalized seizures at 12 months. Differences were not significant. Outcome tended to be better in patients younger than 12 years of age compared with the older age group, but the difference was significant at 6 months only. Our results suggest that some patients with intractable focal epilepsy may respond favorably to the ketogenic diet and that this option should be considered if epilepsy surgery is not possible.

Adolescent↗
PubMed2000

The prenatal diagnosis of Binder syndrome before 24 weeks of gestation: case report.

A case of Binder syndrome was diagnosed at 21 weeks of gestation using two-dimensional and three-dimensional ultrasound. The first indication of any abnormality was a flattened fetal nose demonstrated in the mid-sagittal plane. Further ultrasound imaging showed the virtual absence of the naso-frontal angle, giving the impression of a flat forehead and small fetal nose. Suspected mild hypertelorism was also seen using transverse and coronal planes. Differential diagnosis of this condition is discussed.

Adult↗
PubMed2000

A trial for comparing methods for eliciting treatment preferences from men with advanced prostate cancer: results from the initial visit.

OBJECTIVE: The objective of this study was to evaluate the convergent validity of 3 types of utility measures: standard gamble, time tradeoff, and rating scale. RESEARCH DESIGN: A prospective cohort of 120 men with advanced prostate cancer were first asked to rank order 8 health states, and then utility values were obtained from each participant for each of the 8 health states through 2 of the 3 techniques evaluated (standard gamble, time tradeoff and rating scale). Participants were randomly assigned to 1 of 3 possible pairs of techniques. The validity of the 3 methods, as measured by the convergence and raw score differences of the techniques, was assessed with ANOVA. The ability of the techniques to differentiate health states was determined. The inconsistencies between rankings and utility values were also measured. Proportions of illogical utility responses were assessed as the percent of times when states with more symptoms were given higher or equal utility values than states with fewer symptoms. RESULTS: There were significant differences in raw scores between techniques, but the values were correlated across health states. Utility values were often inconsistent with the rank order of health states. In addition, utility assessment did not differentiate the health states as well as the rank order. Furthermore, utility values were often illogical in that states with more symptoms received equal or higher utility values than states with fewer symptoms. CONCLUSIONS: Use of the utility techniques in cost-effectiveness analysis and decision making has been widely recommended. The results of this study raise serious questions as to the validity and usefulness of the measures.

Aged↗
PubMed1999

Frozen in time: life in the face of chronic care cutbacks.

Kathy Cook won the $750 first prize in CMAJ's 7th Annual Amy Chouinard Memorial Essay Contest. The deadline for entries to the contest, which is designed to stimulate interest in medical writing among journalism students, is June 1. Entries should be forwarded to the news and features editor. In her winning essay, Cook explores the frustrations and quality-of-life issues that arise in a chronic care institution that is trying to operate in the midst of serious funding cuts.

Adult↗
PubMed1999

Assessing the performance of utility techniques in the absence of a gold standard.

BACKGROUND: Utility techniques are the most commonly used means to assess patient preferences for health outcomes. However, whether utility techniques produce valid measures of preference has been difficult to determine in the absence of a gold standard. OBJECTIVE: To introduce and demonstrate two methods that can be used to evaluate how well utility techniques measure patients' preferences. SUBJECTS AND DESIGN: Patients treated for advanced prostate cancer (n = 57) first ranked eight health states in order of preference. Four utility techniques were then used to elicit patients' utilities for each health state. MEASURES: The rating scale, standard gamble, time trade-off, and a modified version of willingness-to-pay techniques were used to elicit patients' utilities. Technique performance was assessed by computing a differentiation and inconsistency score for each technique. RESULTS: Differentiation scores indicated the rating scale permitted respondents to assign unique utility values to about 70% of the health states that should have received unique values. When the other techniques were used, about 40% or less of the health states that should have received unique utility scores actually did receive unique utility scores. Inconsistency scores, which indicate how often participants assign utility scores that contradict how they value health states, indicated that the willingness-to-pay technique produced the lowest rate of inconsistency (10%). However, this technique did not differ significantly from the rating scale or standard gamble on this dimension. CONCLUSIONS: Differentiation and inconsistency offer a means to evaluate the performance of utility techniques, thereby allowing investigators to determine the extent to which utilities they have elicited for a given decision problem are valid. In the current investigation, the differentiation and inconsistency methods indicated that all four techniques performed at sub-optimal levels, though the rating scale out-performed the standard gamble, time trade-off, and willingness-to-pay techniques.

Aged↗
PubMed1998

Fish consumption and breast milk PCB concentrations among Mohawk women at Akwesasne.

A study was conducted to determine the relation between the consumption of contaminated local fish and concentrations of total polychlorinated biphenyls (PCBs) and 68 PCB congeners in the milk of nursing Mohawk women residing near three hazardous waste sites. From 1986 to 1992, 97 Mohawk women were interviewed and donated at least 50 ml of breast milk. The comparison population consisted of 154 Caucasians. After adjustment for potential confounders, Mohawk mothers who gave birth in 1986-1989 had a geometric mean milk total PCB concentration of 0.602 ppm (fat basis) compared with 0.375 ppm for the control group (p = 0.009). These Mohawk women also had significantly higher geometric mean concentrations of nine congeners. Beginning in 1990, however, there were no significant differences between the Mohawk women and the comparison group. Estimated cumulative lifetime exposure from local fish consumption was significantly related to milk total PCB and to three congeners only among those Mohawks who gave birth from 1986 to 1989. The reduction in breast milk PCB concentrations parallels a corresponding decrease in local fish consumption and may be the result of the advisories that have been issued over the past decade recommending against the consumption of local fish by pregnant and nursing Mohawk women.

Adult↗
PubMed1998

Improved ankle function in children with cerebral palsy after computer-assisted motor learning.

The effect of biofeedback training on ankle function was studied in young children with cerebral palsy (CP) during a pilot study and a 6-week follow-up study. Patients underwent range of motion (ROM) and ankle dorsiflexor (DF) strength training in a laboratory 3 days per week, receiving auditory and visual feedback. An at-home programme used portable EMG units to help train DF muscle recruitment on the remaining days. Independent outcome measures included DF strength, active ROM, and tapping ability pretraining and 6 weeks and 14 months posttraining. Tapping ability increased significantly in the trained leg posttraining. It then fell significantly at the 6-weeks posttraining test, but remained significantly higher than pretest levels, and returned to pretraining levels by 14 months. Passive ROM was unchanged, but active ROM increased significantly in the trained leg. DF strength increased in most children posttraining in both the pilot and main study. Increased motor-unit recruitment is believed to explain the increases in DF strength and active ROM. These results suggest that biofeedback training can improve ankle function, and the implications for gait are discussed.

Ankle↗
PubMed1998

Development and validation of a simple questionnaire to facilitate identification of women likely to have low bone density.

The relationship between low bone mass and risk of fracture is well documented. Although bone densitometry is the method of choice for detecting low bone mass, its use may be limited by the availability of equipment, cost, and reimbursement issues. Improved patient selection for bone densitometry might increase the cost-effectiveness of screening for osteoporosis, a goal we sought to achieve by developing and validating a questionnaire based solely on patient-derived data. Responses to the questionnaire were used to assign postmenopausal women to one of two groups: (1) those unlikely to have low bone mineral density (defined as 2 standard deviations or more below the mean bone mass at the femoral neck in young, healthy white women) and therefore probably not currently candidates for bone densitometry; and (2) those likely to have low bone mineral density and therefore probably candidates for bone densitometry. We asked community-dwelling perimenopausal and postmenopausal women attending one of 106 participating multispecialty centers (both academic and community based) to complete a self-administered questionnaire and undergo bone density measurement using dual x-ray absorptiometry. We used regression modeling to identify factors most predictive of low bone density at the femoral neck in the postmenopausal group. A simple additive scoring system was developed based on the regression model. Results were validated in a separate cohort of postmenopausal women. Data were collected from 1279 postmenopausal women in the development cohort. Using only six questions (age, weight, race, fracture history, rheumatoid arthritis history, and estrogen use), we achieved a target of 89% sensitivity and 50% specificity. The likelihood ratio was 1.78. Validation in a separate group of 207 postmenopausal women yielded 91% sensitivity and 40% specificity. Assuming population characteristics similar to those of our development cohort, use of our questionnaire could decrease the use of bone densitometry by approximately 30%. Sensitivity and specificity can be varied by changing the level for referral for densitometry to provide the most cost-effective use within a particular healthcare setting. Thus use of our questionnaire, an inexpensive prescreening tool, in conjunction with physician assessment can optimize the use of bone densitometry and may lead to substantial savings in many healthcare settings where large numbers of women require evaluation for low bone mass.

Bone Density↗
PubMed1997

Determination of nitrite and nitrate in human serum.

A simple and effective assay for nitrite and nitrate in human serum has been developed using ion chromatography. Initial experiments using isocratic carbonate-bicarbonate elution with conductivity detection on a Dionex QIC system with an AS4A-SC column showed promise but were unsatisfactory because of co-elution problems with nitrite. Carbonate and chloride were investigated as eluents using a gradient system, and direct UV detection at 214 nm was used in place of conductivity detection. Dionex AS4A, AS9A, AS12, Nucleopac PA-100 and Carbopac PA-100 columns were compared for selectivity and resistance to overload. The final method, using a chloride concentration gradient, pH buffering and direct UV detection with a Carbopac PA-100 column, shows good resolution, does not suffer from chloride overload and is simple to use. The method is being used in an investigation of the role of nitric oxide in pre-eclampsia, a hypertensive disorder during pregnancy.

Chromatography, Ion Exchange↗
PubMed1997

The Child and Adolescent Trial for Cardiovascular Health (CATCH): intervention, implementation, and feasibility for elementary schools in the United States.

The Child and Adolescent Trial for Cardiovascular Health (CATCH) was the largest school-based field trial ever sponsored by the National Institutes of Health. The trial demonstrated positive changes in the school food service and physical education program, as well as in students' cardiovascular health behaviors. Because the CATCH intervention programs were implemented in 56 schools (in four states) that were typical of schools throughout the United States, their reception by schools and degree of implementation provide evidence about their feasibility for schools nationally. Extensive process evaluation data were collected from students, teachers, school food service personnel, and physical education specialists throughout the three school years of the CATCH intervention. Four of the CATCH programs--school food service, physical education, classroom curricula, and home programs--were assessed over the three school years. The process data provide information on participation, dose, fidelity, and compatibility of the CATCH programs in the intervention schools for these programs. High levels of participation, dose, fidelity, and compatibility were observed for the four programs during the 3 school years. CATCH emerges as a model of a feasible multilevel health promotion program to improve eating and exercise behaviors for elementary schools in the United States.

Adolescent↗
PubMed1994

Comparative studies of taxol and taxotere on tumor growth and lymphocyte functions.

Taxotere, a semisynthetic derivative similar to taxol, has shown promising results in vitro and in preliminary in vivo studies. We have previously reported that taxol at 10 micrograms/ml suppressed the cytotoxic function and activation of natural killer cells and major histocompatibility nonrestricted (MHC-NR) T cells against the ovarian cell line OV-2774 and the erythroleukemia cell line K-562. In this paper, we investigated the effect of taxotere on lymphocyte function and found that a suppression of MHC-NR cytotoxicity of naive lymphocytes is only seen at higher doses of taxotere (50 micrograms/ml). At the concentrations of 10 and 50 micrograms/ml, taxotere did not have any effect on the cytotoxic function of IL-2-preactivated lymphocytes. On the contrary, both taxol and taxotere caused a significant suppression of lymphocyte growth and activation with IL-2 at 10 and 50 micrograms/ml. Both drugs (at the concentration of 10 micrograms/ml) were potent inhibitors of the growth of the tumor cell lines OV-2774 and K-562. In conclusion, despite the fact that taxotere shares with taxol a potent antitumor effect, it seems to be less suppressive for lymphocyte cytotoxicity, an effect clearly desirable in cancer therapy.

Antineoplastic Agents, Phytogenic↗