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Biomedical subjects

David J Cook

Publications and source records attributed to David J Cook.

17 recordsLinked to original sources
PubMed2005

On-line MS/MS monitoring of acrylamide generation in potato- and cereal-based systems.

An on-line MS/MS technique was used to study the generation of acrylamide in rye-, wheat-, and potato-based systems during cooking. Acrylamide release to the gas phase was monitored continuously and was correlated with the acrylamide content of samples using a calibration based upon the partition of [1,2,3-(13C3)]acrylamide. On-line results at 180 degrees C were compared with data relating to the same systems obtained through GC-MS analysis. Agreement between the two techniques was notable, both in terms of the temporal profiles of acrylamide generation and when comparing the relative magnitudes of results for potato, wheat, and rye determined by each method. The effects of pH (citric acid) and added amino acids (soy protein hydrolysate) on the generation of acrylamide in hydrated potato flake were modeled at 180 degrees C. It was concluded that a combined treatment of low levels of each additive could result in significant reductions in acrylamide, although the effects of such treatments on sensory properties such as color and flavor remain to be evaluated.

Acrylamide↗
PubMed2005

On line monitoring of acrylamide formation.

A system to monitor the formation of acrylamide in model systems and from real food products under controlled conditions of temperature, time and moisture content has been developed. By humidifying the gas that flows through the sample, some control over moisture content can be affected. Results are presented to show the validity and reproducibility of the technique and its ability to deliver quantitative data. The effects of different processing conditions on acrylamide formation and on the development of color, due to the Maillard reaction, are evaluated.

Acrylamide↗
PubMed2005

Changing incidence, type, and natural history of conduction defects after coronary artery bypass grafting.

BACKGROUND: Cardiac conduction defects occur after cardiac surgery. We hypothesized that population aging and increased use of beta-blockers would increase the incidence of new conduction defects after coronary surgery. METHODS: We examined the medical records of 800 coronary artery bypass grafting (CABG) patients (400 from 1991 and 400 from 2001). Exclusion criteria included the following: preexisting conduction defect, permanent pacemaker, and perioperative atrial fibrillation, leaving 303 and 269 patients, respectively, included in the two study years. The incidence, type, and persistence of new conduction defects were determined from the preoperative, postoperative, and the predischarge electrocardiogram. Multivariate analysis identified predictors of new defects. RESULTS: Study populations were well-matched. There was a marked decrease in the incidence of new postoperative conduction defects from 1991 (19%) to 2001 (6%). There was also a change in the most frequently occurring block, from a right-bundle-branch-block in 1991 (10%) to first-degree atrioventricular block (3%) in 2001. Finally, conduction defects in 1991 were more transient. While 19% of 1991 patients showed a conduction defect early postoperatively, only 9% were persistent. In 2001, the incidence of conduction defects at discharge (7%), was equivalent to that early postoperatively (6%). Predictors of new conduction defects included year of operation, age, intraaortic balloon counterpulsation, number of vessels bypassed, and crystalloid cardioplegia. CONCLUSIONS: Our results were the opposite of those predicted. Our report identifies a changing incidence, type, and natural history of conduction defects after CABG. Our comparison demonstrated a decrease in the incidence of new conduction defects, as well as a qualitative change in the defects identified. Multivariate analysis provided predictors of new conduction defects after CABG.

Adult↗
PubMed2005

Quantitative evaluation of "Can It Happen in Kansas: Response to Terrorism and Emerging Infections".

PURPOSE: This study describes the evaluation of a 2-year plan to train 10 percent of Kansas' multidisciplinary health professionals for response to terrorism and emerging infections. This project was part of a national effort covering 19 states funded by the Health Resources and Services Administration in 2003. METHODS: The initial training occurred in six 2-day workshops. A terrorism preparedness questionnaire was developed to assess Health Resources and Services Administration terrorism response competencies/learning objectives. These were measured before, after, and 3 months after training in a hybrid cross-sectional and cohort follow-up design. RESULTS: Health professionals' mean scores significantly improved on all four Health Resources and Services Administration terrorism self-reported competencies from pretest to posttest. Three months posttraining, health professionals' mean scores decreased slightly but remained significantly higher than their pretest scores. CONCLUSIONS: This project prepared healthcare professionals to respond to the medical consequences of terrorism. The integration of core competencies into the evaluation plan allowed for trainees to evaluate their confidence and abilities. The evaluation plan and curriculum may serve as useful tools for preparation of healthcare workers nationwide, with the potential to rebuild the public health infrastructure to assume preparedness responsibilities.

Adult↗
PubMed2005

Diffusion theory and telemedicine adoption by Kansas health-care providers: critical factors in telemedicine adoption for improved patient access.

Twenty counties in Kansas were randomly selected from those designated as rural on the basis of their populations. A sample of 356 physicians and physicians' assistants in these counties was chosen. A postal survey was sent to the identified providers up to three times. One hundred and eighty-six of the questionnaires were returned (a response rate of 52%). In all, 76% of the respondents were physicians, 76% were men and 42% were family practitioners. Practitioners were classified as adopters or non-adopters of telemedicine, based on their report of whether they had ever referred one or more patients for a health-care consultation via telemedicine. Of the 167 participants who marked this item, 30 (18%) were adopters and 137 (82%) were non-adopters. Among the adopters, 16 (53%) said that they expected to use telemedicine with about the same frequency or more often in the future. In contrast, 61 (45%) non-adopters reported that they did not expect to refer patients by telemedicine in the future and 51 (37%) were unsure. Neither age (r = 0.16, P = 0.44) nor gender (chi2 = 2.35, P = 0.13) was related to the adoption variable or the number of referrals made to telemedicine clinics. The results suggest that adopters and non-adopters of telemedicine perceive its value very differently, and that an opportunity exists to promote the concept to non-adopters more effectively.

Age Factors↗
PubMed2004

Persistent renal cortical scintigram defects in children 2 years after urinary tract infection.

BACKGROUND: Renal cortical scintigraphic studies challenge the role of vesicoureteric reflux in renal scar development, emphasizing instead the part played by acute pyelonephritis. OBJECTIVE: To determine the prevalence of renal cortical defects in a child cohort 2 years after the child's first diagnosed urinary tract infection and to analyze the relationship of these defects with acute illness variables, primary vesicoureteric reflux and recurrent infections. MATERIALS AND METHODS: In a prospective cohort study, 193 children younger than 5 years with their first proven urinary tract infection underwent renal sonography, voiding cystourethrogram, and renal cortical scintigraphy within 15 days of diagnosis. Two years later, 150 of the 193 children, or 77.7%, had a further renal cortical scintigram, including 75, or 86.2%, of the 87 children who had acute scintigraphic defects. The relationship of cortical defects to age, gender, pre-treatment symptom duration, hospitalization, presence and grade of vesicoureteric reflux, and recurrent urinary tract infections was evaluated. RESULTS: Overall, 20 of the 150 (13.3%; 95% confidence interval (CI) 8.3, 19.8) children had persistent defects 2 years after infection. This included 20 of 75 (26.7%; 95% CI 17.1, 38.1) with initially abnormal scintigrams. No new defects were detected. Although acute defects were more common in the young, those with persistent defects were older (median ages 16.4 vs. 6.8 months, P=0.004) than those with transient abnormalities. After adjustment for age, persistent defects were no longer associated with gender and were not predicted by acute illness variables, primary vesicoureteric reflux or recurrent infections. CONCLUSIONS: Renal cortical scintigraphic defects persisted in approximately one-quarter of young children after their first proven urinary tract infection. The associated clinical features, however, failed to predict scar formation. It is possible that some of the scintigraphic defects preceded the infection by arising from either previously undiagnosed acute pyelonephritis or from underlying congenital dysplasia. The etiology of scars may be best addressed by determining whether prevention of urinary tract infections from birth avoids post-natal scar acquisition or extension.

Chi-Square Distribution↗
PubMed2004

A cost analysis of a tele-oncology practice in the United States.

Oncology services have been provided by telemedicine from the University of Kansas Medical Center (KUMC) for almost 10 years. We have analysed the costs associated with providing tele-oncology clinics to a rural Kansas town for two fiscal years, 1995 and 2000. The aim was to compare recent tele-oncology costs with those of the first year of tele-oncology practice. A study conducted in 1995 showed that the average cost was $812 per telemedicine consultation. Data from fiscal year 2000 showed that the average cost was $410 per telemedicine consultation, a decrease of almost 50%. As the tele-oncology practice in Kansas continues to grow, it can be expected that the costs associated with providing tele-oncology services will continue to decline.

Costs and Cost Analysis↗
PubMed2003

Effects of hydrocolloid thickeners on the perception of savory flavors.

The perceived intensities of savory flavors in hydrocolloid-thickened solutions were investigated using sensory paired comparison tests between two distinct thickener concentrations (high and low viscosities). The perceived saltiness of 3.5 g/L NaCl was found to be significantly reduced (P < 0.01) at the higher thickener concentration of both hydroxypropylmethyl cellulose (HPMC) and lambda-carrageenan, relative to the lower concentration. Mushroom flavor (8 ppm of 1-octen-3-ol with 3 g/L NaCl) was perceived as significantly more intense (P < 0.05) in 1.7 g/L lambda-carrageenan as compared with the same concentration of flavoring in 10.2 g/L lambda-carrageenan. Garlic flavor (2.5 ppm of diallyl disulfide with 2 g/L NaCl) was perceived to be significantly more intense in 2 g/L HPMC (P < 0.01) than in 10 g/L HPMC. However, when the NaCl concentration in the more viscous sample was increased to 3 g/L, the garlic flavor intensities of the two systems were not significantly different, suggesting a perceptual interaction (enhancement) between salt taste and garlic flavor. In vivo aroma release measurements from the same samples, using API-MS, showed that hydrocolloid concentration did not significantly alter the amount of mushroom or garlic aromas released when solutions were consumed. It was concluded that changes in perceived saltiness were driving the reduction in savory flavor perception even though the aroma stimulus was unchanged (a taste-aroma interaction). These findings parallel previous results in sweet hydrocolloid-thickened solutions.

Agaricales↗
PubMed2003

Oral shear stress predicts flavour perception in viscous solutions.

The perception of sweetness and flavour were studied in viscous solutions containing 50 g/l sucrose, 100 p.p.m. iso-amyl acetate and varying concentrations of three hydrocolloid thickeners (guar gum, lambda-carrageenan and hydroxypropylmethyl cellulose). Zero-shear viscosity of the samples ranged from 1 to 5000 mPas. Perception of both sweetness and aroma was suppressed at thickener concentrations above c* (coil overlap concentration, the point at which there is an abrupt increase in solution viscosity as thickener concentration is increased). Sensory data for the three hydrocolloids was only loosely correlated with their concentration relative to c* (c/c* ratio), particularly above c*. However, when perceptual data were plotted against the Kokini oral shear stress (tau), calculated from rheological measurements, data for the three hydrocolloids aligned to form a master-curve, enabling the prediction of flavour intensity in such systems. The fact that oral shear stress can be used to model sweetness and aroma perception supports the hypothesis that somatosensory tactile stimuli can interact with taste and aroma signals to modulate their perception.

Adult↗
PubMed2003

An estimation of costs of a pediatric telemedicine practice in public schools.

BACKGROUND: Costs per consult are a vital consideration in determining the viability of a telemedicine practice. This study estimated total, average, and marginal cost curves for an ambulatory pediatric telemedicine practice. OBJECTIVE: The objective of this study was to estimate the costs of providing 386 telemedicine clinical consults at school clinics during one school year (September, 1999 to May, 2000). Cost curves were used to estimate costs of clinics with varying numbers of consults. RESEARCH DESIGN: This analysis used cost data from school clinics and a university medical center, which provided physician inputs. Standard cost-accounting procedures were used. SUBJECTS: Cost analyses were conducted using 10 school clinics. Three hundred eighty-six consults were completed with 286 children. Seventy-one percent of the children were black or Hispanic. RESULTS: The average costs of a telemedicine consult ranged from a high of $7328.17 when only one consult was done to a low of $173.13 when 129 consults were completed. At 165 consults, extrapolations from the cost curves suggested that the average costs of a telemedicine consult and a medical center pediatric ambulatory consult were approximately equal, a little more than $153. At 200 consults, telemedicine was estimated to be equal to or less costly than conventional ambulatory care visits by some 9.5%. CONCLUSIONS: Point and CI estimates of average costs suggest that telemedicine is cost competitive with conventional clinics when 200 or more consults are provided. The limited evidence available suggests that telemedicine consults also may be quality competitive.

Ambulatory Care↗
PubMed2002

Time course of transient cortical scintigraphic defects associated with acute pyelonephritis.

BACKGROUND: Acute pyelonephritis is distinguished from renal scarring using repeat cortical scintigraphy. The defects of acute pyelonephritis resolve, while those of scars persist. OBJECTIVE: To determine the duration of reversible cortical defects following acute pyelonephritis and the time interval required to differentiate infection from scars. MATERIALS AND METHODS: An observational prospective study of 193 children (386 kidneys) aged less than 5 years following their first proven urinary tract infection (UTI). Renal cortical scintigraphic defects were detected in 112 (29%) kidneys within 15 days of diagnosis. Of these, 95 underwent repeat renal cortical scans 2 years after the UTI, including 50 with additional scans performed within 2-6 months of infection. RESULTS: Of the 50 kidneys undergoing a second renal cortical scan within 2-6 months of the first UTI, 22 (44%) had persistent defects. A third scan was performed on 17 (77%) kidneys after 2 years, by which time defects had resolved in another 8 (47%) kidneys. The predictive value of defects detected within 2-6 months of UTI representing scars is 53% (95% CI 28, 77). Overall, nine (18%) kidneys with initial renal cortical abnormalities had permanent defects. In the 45 kidneys undergoing a second cortical scan more than 6 months after the UTI, 11 (24%) had persistent defects. None of the 95 kidneys undergoing serial scans developed new or larger defects. CONCLUSIONS: Renal scars may not be reliably diagnosed by cortical scintigraphy performed within 6 months of UTI because the inflammatory lesions may not have fully resolved.

Acute Disease↗
PubMed2002

Profound reduction in brain embolization using an endoaortic baffle during bypass in swine.

BACKGROUND: Cerebral embolization during cardiopulmonary bypass is an important cause of neurologic injury. This study determined whether an endoaortic baffle catheter (Cardeon Cobra Catheter; Cardeon Corporation, Cupertino, CA) could substantially reduce cerebral embolization in a swine cardiopulmonary bypass model. METHODS: Sixteen 60 kg pigs underwent cardiopulmonary bypass; 8 animals with the Cobra baffle (Cardeon Corporation, Cupertino, CA) deployed, and 8 with the same cannula without baffle deployment. The animals were embolized with 72,000 fluorescent microspheres (97 to 100 microm) at normothermia. At the end of the experiment, the brains were removed and microspheres were isolated from eight regions. RESULTS: During embolization, the two groups were equivalent with regard to pump flow, mean arterial pressure, temperature, Hgb and PaCO2. Deployment of the Cobra baffle reduced embolization to every brain region. Deployment of the baffle reduced total brain embolization by 89%. There was a mean of 61+/-60 emboli per gram in the control animals and 7+/-24 emboli per gram in those animals in which the baffle was deployed. CONCLUSIONS: Cerebral embolization is profoundly reduced by use of the Cobra baffle aortic cannula. The application of this device may reduce postcardiac surgical neurologic injury.

Animals↗
PubMed2002

Reduction in brain embolization using the Aegis aortic cannula during bypass in swine.

BACKGROUND: Cerebral embolization during cardiopulmonary bypass (CPB) is an important cause of neurologic injury. This study determined whether a new aortic cannula (Cardeon Aegis) could substantially reduce brain embolization in a swine CPB model. METHODS: Fourteen 70-kg pigs underwent normothermic CPB, 7 animals with the Aegis device and 7 with a control cannula. Cerebral blood flow was determined using 15-microm fluorescent microspheres before bypass and twice during CPB. After the second bypass CBF measurement, animals were embolized with 120,000 78-microm fluorescent microspheres at normothermia. At the end of the experiment the brain, eyes, kidneys, myocardium, and small bowel were removed and the microspheres isolated. RESULTS: Cerebral blood flow was equivalent between groups before bypass and during both bypass periods. While the two groups were equivalent with regard to pump flow, temperature, hemoglobin, and PaCO2, use of the Aegis cannula markedly reduced embolization to three of four brain regions. Deployment of the baffle reduced total brain embolization by 91% from a mean of 22 +/- 21 emboli per gram in the control animals to 2 +/- 6 emboli per gram in animals receiving the Aegis device. CONCLUSIONS: Cerebral blood flow with the Aegis device is equal to or greater than that observed under nonbypass conditions and that seen with conventional aortic cannulas. However, cerebral embolization is profoundly reduced by use of the Aegis device. The application of this cannula may reduce postcardiac surgical neurologic injury.

Animals↗
PubMed2002

Use of the Cobra catheter for targeted temperature management during cardiopulmonary bypass in swine.

BACKGROUND: The purpose of this investigation was to determine whether temperatures of the aortic arch and descending aortic circulations could be controlled independently during cardiopulmonary bypass with a cannula possessing an endoaortic baffle (Cobra; Cardeon, Cupertino, Calif). METHODS: After Institutional Animal Care and Use Committee approval, 12 pigs weighing 60 kg were started on bypass through a sternotomy. A dual-lumen endoaortic cannula with a deployable baffle was used for arterial cannulation. Bypass was initiated at 37 degrees C, and control measurements were obtained. The baffle was then inflated with saline solution, segmenting blood flow along the greater and lesser curvatures of the aortic arch. Parallel heat exchangers were used to independently control temperature of the arch and descending aortic perfusates. Cerebral and systemic temperatures were recorded continuously. RESULTS: During cardiopulmonary bypass, mean flow and arterial pressure were maintained at 2.4 to 2.6 L x min(-1) x m(-2) and 60 to 70 mm Hg, respectively. With aortic flow distributed by the baffle, a 5 degrees C temperature differential between brain (30 degrees C) and body (35 degrees C) was established in a mean of 5 +/- 2 minutes. Mean brain and corporeal temperatures of 27 degrees C and 35 degrees C were then maintained over 60 minutes. Relative to control, internal jugular and inferior vena cava oxygen saturations increased during targeted temperature control with the device. CONCLUSIONS: The Cobra cannula allows for independent control of brain and body temperature while providing satisfactory hemodynamics. Application of this temperature management strategy may offer cerebral protection and the advantages of warm systemic bypass temperature.

Animals↗
PubMed2002

Explaining the adoption of telemedicine services: an analysis of a paediatric telemedicine service.

Since 1998, over 1300 telemedicine consultations have been provided to 12 schools in Kansas City. Despite the success of the programme, effective utilization of services has not occurred at all sites. We used a focus group and survey methods to investigate barriers to and catalysts for service adoption. The results showed that the school nurses strongly supported the programme. They valued its ability to provide health-care for the children and they welcomed their enhanced role. However, technical complexities and difficulties in obtaining parental consent were found to impede adoption. The nurses also expressed frustration with school personnel who had a poor understanding of their role in general as well as that of the telemedicine service. A new state reimbursement policy may promote greater understanding and provide a financial incentive for schools to adopt the telemedicine service.

Attitude of Health Personnel↗