Biomedical subjects
Publications and source records attributed to M Gardner.
Allograft aortic root replacement for primary aortic valve or ascending aortic root pathology is the favored method of technical implantation. Results in 418 patients over 15 years demonstrate exceedingly low early mortality (<1%), complete eradication of preoperative endocarditis but poor long-term durability in the young age group of 20 years or less.
BACKGROUND: Patients with resuscitated ventricular tachyarrhythmias (ventricular tachycardia/ventricular fibrillation) benefit from implantable cardioverter-defibrillators (ICDs) compared with medical therapy. We hypothesized that the patients who benefit most from an ICD are those at greatest risk of death. METHODS AND RESULTS: In the Canadian Implantable Defibrillator Study (CIDS), 659 patients with resuscitated ventricular tachyarrhythmias were randomly assigned to receive an ICD or amiodarone and were then followed for a mean of 3 years. There were 98 and 83 deaths in the amiodarone and ICD groups, respectively. We used multivariate Cox analysis to assess the impact of baseline parameters on the mortality in the amiodarone group. Reduced left ventricular ejection fraction, advanced age, and poor NYHA status identified high-risk patients (P=0.0001 to 0.0009). Quartiles of risk were constructed, and the mortality reduction associated with ICD treatment in each quartile was assessed. There was a significant interaction between risk quartile and the ICD treatment effect (P=0.011). In the highest risk quartile, there was a 50% relative risk reduction (95% CI 21% to 68%) of death in the ICD group, whereas in the 3 lower quartiles, there was no benefit. Patients who are most likely to benefit from an ICD can be identified with a simple risk score (>/=2 of the following factors: age >/=70 years, left ventricular ejection fraction </=35%, and NYHA class III or IV). Thirteen of 15 deaths that were prevented by the ICD occurred in patients with >/=2 risk factors. CONCLUSIONS: In CIDS, patients at highest risk of death benefited most from ICD therapy. These can be identified easily on the basis of age, poor ventricular function, and poor functional status.
BACKGROUND/PURPOSE: Intestinal failure is a complex metabolic process that results from malabsorption and malnutrition and provides challenges for a variety of pediatric subspecialists. The purpose of this study was to evaluate the effect of coordinated interdisciplinary team management of children with intestinal failure on nutritional outcome measures. METHODS: The Intestinal Care Center (ICC) is staffed with an interdisciplinary team of pediatric specialists including a gastroenterologist, pediatric surgeon, transplant surgeon, clinical dietitians, and a nutrition support nurse. Using an established registry, the authors conducted a comprehensive evaluation of patient data including anthropometric measures, organ system function, and mode of nutrition support. Disease-associated complications including micronutrient deficiencies, growth delay, and death also were monitored. Nutritional outcome was assessed by transition from enteral to oral feeding, cessation of total parenteral nutrition (TPN), and maintenance of linear growth. RESULTS: Since the inception of the ICC in 1996, 103 patients (69 boys, 34 girls) with intestinal failure have been evaluated with a median age of 2.6 years (range, 0.2 to 21.3 years). Mode of nutritional therapy on initial consultation included TPN (n = 76, 74%), enteral feedings (n = 6, 6%) and oral intake (n = 21, 20%). After intensive management of the 76 patients who were TPN dependent, 22 (29%) subsequently have been weaned from TPN (duration, 0.2 to 17.5 years) to oral (n = 14), oral-enteral (n = 4) or enteral feedings (n = 4). Of the 6 patients who were receiving enteral feedings, 4 (67%) were transitioned to oral feedings. Sixty-eight patients (66%) had evidence of hepatic disease. Of these, 10 underwent transplant, and 23 died (2 posttransplant). Linear growth velocity of neither pre- nor postpubescent patients significantly improved during the 2-year study period. CONCLUSION: Data registry establishment and concurrent interdisciplinary team management of children with intestinal failure provides for innovative treatment approaches and a foundation for retrospective or prospective assessment of children with disease.
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BACKGROUND/PURPOSE: Although the mortality, morbidity, and spectrum of associated injuries in children with pelvic fractures have been extensively studied, little is known about the functional outcomes in these patients. The authors examined retrospectively functional independence measurement (FIM) at discharge in children with pelvic fractures to determine how it should influence their management protocol. METHODS: The authors reviewed the records of all patients who sustained pelvic fractures between 1993 and 1998 in the trauma registry of a level I pediatric trauma center. Patients were stratified according to demographics, type of pelvic fracture, functional independence measurement, and discharge disposition. Fractures graded 1, 2, or 3 were defined as stable, whereas grade 4 fractures were deemed unstable. RESULTS: A total of 88 children sustained pelvic fractures. Seventy-four percent had stable fractures, whereas 26% sustained unstable fractures. There was no difference in age or sex between the groups; boys were more commonly injured than girls. Motor vehicle-related crashes accounted for most injuries. The mean injury severity score (ISS) for patients with a stable fracture was 17 +/- 14 and 20 +/- 13 for unstable fractures. There was no difference in overall hospitalization nor intensive care unit stay between the unstable and stable fracture patients. Eighty percent of the patients with unstable and 52% of the patients with stable pelvic fractures were dependent based on locomotion, and similar proportions were seen for the transfer category. CONCLUSIONS: Short-term function appears to be significantly impaired in a high percentage of children with stable and unstable pelvic fractures. Therefore, aggressive rehabilitation should be instituted early in all children with pelvic fractures to achieve optimal functional outcome.
The breathing pattern in the aquatic caecilian Typhlonectes natans was investigated by recording airflow via a pneumotachograph under unrestrained normal physiological conditions. Ventilatory mechanics were assessed using airflow and pressure measurements from the buccal cavity and trachea. The breathing pattern consisted of an expiratory phase followed by a series of 10-15 small buccal pumps to inflate the lung, succeeded by a long non-ventilatory period. T. natans separate the expiratory and inspiratory gases in the buccal cavity and take several inspiratory pumps, distinguishing their breathing pattern from that of sarcopterygians. Hydrostatic pressure assisted exhalation. The tracheal pressure was greater than the water pressure at that depth, suggesting that pleuroperitoneal pressure as well as axial or pulmonary smooth muscles may have contributed to the process of exhalation. The frequency of lung ventilation was 6.33+/-0.84 breaths h(-)(1), and ventilation occurred via the nares. Compared with other amphibians, this low ventilatory frequency suggests that T. natans may have acquired very efficient pulmonary respiration as an adaptation for survival in their seasonally fluctuating natural habitat. Their respiratory pathway is quite unique, with the trachea separated into anterior, central and posterior regions. The anterior region serves as an air channel, the central region is attached to the tracheal lung, and the posterior region consists of a bifurcated air channel leading to the left and right posterior lungs. The lungs are narrow, elongated, profusely vascularized and compartmentalized. The posterior lungs extend to approximately two-thirds of the body length. On the basis of their breathing pattern, it appears that caecilians are phylogenetically derived from two-stroke breathers.
Throughout the course of the 20th century, many observers have noted important tensions and antipathies between public health and medicine. At the same time, reformers have often called for better engagement and collaboration between the 2 fields. This article examines the history of the relationship between medicine and public health to examine how they developed as separate and often conflicting professions. The historical character of this relationship can be understood only in the context of institutional developments in professional education, the rise of the biomedical model of disease, and the epidemiologic transition from infectious disease to the predominance of systemic chronic diseases. Many problems in the contemporary burden of disease pose opportunities for effective collaborations between population-based and clinical interventions. A stronger alliance between public health and medicine through accommodation to a reductionist biomedicine, however, threatens to subvert public health's historical commitment to understanding and addressing the social roots of disease.
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The present study sought to determine whether the increased postural instability produced by a spoken mental task was due to competing demands for attentional resources or perturbation of posture by articulation. Postural sway was measured in 36 normal subjects under the following conditions: repeating a number aloud (articulation), counting backwards aloud in multiples of seven (articulation and attention), counting backwards silently (attention), and no mental task (neither articulation nor attention). Articulation resulted in a significant increase in sway, whereas no effect of attention was observed. We conclude that in order to accurately assess the effect of attentional demands on postural control, it is important to eliminate or control the effects of articulation.
BACKGROUND/PURPOSE: A number of pediatric patients with short bowel syndrome (SBS) manifest growth failure despite aggressive nutritional support. Exogenous growth hormone (GH) therapy in children with SBS has proved disappointing. The purpose of this study was to determine if there were characteristic patterns of GH, IGF-1, or IGFBP-3 levels in pediatric SBS patients with profound growth failure in an effort to elucidate an early strategic approach to management of SBS in the subpopulation. METHODS: Forty patients (29 boys, 11 girls; mean age, 5.3 years; range, 0.5 to 18.6 years) with SBS (<30% total bowel length) who received intensive nutrition support and follow-up underwent serological tests for GH, IGF-1, IGFBP-3, and thyroid function. Height (HT), weight (WT), and bone age were assessed relative to age-appropriate percentiles. Growth failure was defined as a HT and WT at less than the fifth percentile and bone age > or = 2 standard deviations below actual age. Residual small bowel length was determined by review of pathological and operative reports. Comparisons between the growth factors, bowel length, and anthropometric data were analyzed by chi2. RESULTS: Two distinct subgroups of patients emerged from our study. Thirty-eight percent of patients (n = 11) had growth failure by anthropometry that was associated significantly with low IGF-1 independently and with both IGF-1 and IGFBP-3 levels (P< 0.05). There were no significant associations with GH level, thyroid function, small bowel length, or the amount of parenteral versus enteral intake in either subgroup of these patients. Low IGF-1 and IGFBP-3 but not GH levels may be indices of intestinal failure in pediatric SBS. Growth in this subpopulation is refractory to aggressive standard approaches to nutritional support and may require early interventions. CONCLUSION: Exogenous IGF-1 and IGFBP-3, not GH, may be beneficial to treat this subpopulation.
The purpose of this study was to determine whether significant attentional resources are required to accurately monitor changes in bodily orientation, using vestibular information. This question was addressed firstly using a dual-task paradigm in which orientation perception tasks and a speeded auditory tone discrimination task were carried out either singly or in combination. For the active orientation perception task, subjects were seated in darkness on a motorised chair which could be rotated about an earth-vertical axis. Following passive angular displacements, subjects were required to return the chair to their perceived starting position, using a joy-stick which controlled chair motion. For the speeded auditory task, subjects pushed a hand-held button as fast as possible when a tone was presented over headphones. When the two tasks were combined, reaction times on the auditory task increased. Reaction time also increased when subjects were simply asked to fixate during rotation. A second experiment demonstrated that if attention was occupied by performance of a demanding mental arithmetic task during the passive rotation, accuracy of subsequently repositioning the chair to the origin declined, implying that change in orientation had been less accurately registered when performing the concurrent mental task. In combination, these findings indicate that a small but significant degree of attention or cognitive effort is necessary to monitor accurately the direction and amplitude of a brief angular rotation, and to suppress vestibulo-ocular reflex eye movement.
This paper reports an approach to the assessment of the validity of environmental monitoring data--a 'data filter'. The strategy has been developed through the UK National Marine Analytical Quality Control (AQC) Scheme for application to data collected for the UK National Marine Monitoring Plan, although the principles described are applicable more widely. The proposed data filter is divided into three components: Part A, 'QA/QC'--an assessment of the laboratory's practices in Quality Assurance/Quality Control; Part B, 'fitness for purpose'--an evaluation of the standard of accuracy that can be demonstrated by activities in (A), in relation to the intended application of the data; and Part C, the overall assessment on which data will be accepted as usable or rejected as being of suspect quality. A pilot application of the proposed approach is reported. The approach described in this paper is intended to formalise the assessment of environmental monitoring data for fitness for a chosen purpose. The issues important to fitness for purpose are discussed and assigned a relative priority order on which to judge the reliability/usefulness of monitoring data.
Fitzroya cupressoides (alerce, Cupressaceae) is a large and exceptionally long-lived conifer, endemic to a restricted area of southern Chile and neighbouring areas of Argentina. As a result of its high economic value, the species has been severely exploited for timber, and remnant populations are fragmented and often highly disturbed. The species is thought to have undergone a major range contraction during the last glaciation. In order to assess the extent of genetic variation using DNA markers within and between populations of this species, samples were obtained from throughout the natural range and analysed for random amplified polymorphic DNA (RAPD) variation. Eight 10-mer and three 15-mer primers were used to produce a total of 54 polymorphic bands. Shannon's diversity estimates were calculated to provide an estimate of the degree of variation within each population. Values varied from 0.343 to 0.636 with only the lowest value differing significantly from the others (Spop = 0.547). This indicated that there is a significant degree of variation within each population, and did not provide evidence for genetic 'bottle-neck' effects within the species. A pairwise distance measure calculated from the RAPD data was used as an input for principal coordinate (PCO) and AMOVA analyses. The first three principal coordinates of RAPD distances described 8.3, 5.9 and 5.4% of the total variance, respectively, and a degree of clustering of samples according to their geographical origin was detectable. AMOVA analysis indicated that although most of the variation (85.6%) was found within populations, a significant proportion (P < 0.002) was attributable to differences between populations. An UPGMA dendrogram constructed using phi ST values derived from AMOVA produced a pattern broadly similar to that produced by the PCO, highlighting differences between three main groups of populations within Chile: those from the northern Coastal Range, the southern Coastal Range and Central Depression, and the Andes. Populations from Argentina also emerged as significantly different from those in Chile. These results are interpreted in the context of the postglacial history of the species, and their implications for the development of conservation strategies for Fitzroya are discussed.
BACKGROUND AND METHODS: Controversy persists regarding the management of pancreatic transection. Over the past 10 years, 51 patients admitted to the Children's Hospital of Pittsburgh sustained blunt pancreatic injuries. We reviewed their medical records to clarify the optimal management strategy and to define distinguishing characteristics, if any, of patients with pancreatic transection. RESULTS: Patients who sustained pancreatic transection had a significantly higher Injury Severity Score, length of stay, serum amylase, and serum lipase, than those patients who sustained pancreatic contusion. Patients who underwent laparotomy within 48 hours of injury for pancreatic transection had a significantly shorter length of stay than those who underwent laparotomy more than 48 hours after injury. CONCLUSION: Serum amylase greater than 200 and serum lipase greater than 1,800 may be useful clinical markers for major pancreatic ductal injury when combined with physical examination. Early operative intervention for pancreatic transection results in shorter length of stay and fewer complications.
The information retrieval systems currently available in general practice, such as Medline, and web search engines are passive and relatively difficult to access during consultations. Emergent technologies, including the National Electronic Library for Health, offer opportunities for more active decision support. We examine the extent to which information retrieval could support primary care consultations by examining the impact of the new technology at different stages of the consultation. We advocate a system whereby professional organisations concerned with quality of care, such as the Royal College of General Practitioners, might contribute the the process.
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BACKGROUND: The objectives were to investigate the factors influencing signal-averaged ECGs (SAECGs) recorded in patients after myocardial infarction (MI) and to develop criteria for predicting arrhythmic events (AEs) that account for these factors. METHODS AND RESULTS: SAECGs were recorded 5 to 15 days after MI in 2461 patients without bundle-branch block. The duration (QRSd), terminal potential (VRMS), and terminal duration (LAS) of the filtered QRS were measured. During follow-up (17 +/- 8 months), AEs (arrhythmic death; ventricular tachycardia, VT; ventricular fibrillation, VF) occurred in 80 patients (3.3%). Receiver operating characteristic curves showed that QRSd discriminated patients with all types of AEs, but VRMS and LAS discriminated only VT patients; QRSd minus LAS also discriminated AE patients. Sex, age, and MI location significantly affected the SAECG; survivors without VT or VF were divided into subgroups (2 sex x 4 age x 2 MI), and QRSd values exceeding the 70th percentile in each subgroup predicted AEs with a sensitivity of 65.4%. An unadjusted QRSd criterion showed the same overall sensitivity and specificity but with less uniform values for each subgroup. A Cox model was constructed by use of multiple prognostic indicators, and in rank order, QRSd, previous MI, and Killip class were predictive of AEs. CONCLUSIONS: SAECG adjustments for sex, age, and MI location did not improve sensitivity and specificity but produced a more uniform predictive performance. The proposed criteria are based only on QRSd, because late potentials (VRMS and LAS) did not discriminate patients with sudden death. Duration of high-level activity during QRS (QRSd-LAS) can predict AEs, suggesting that the arrhythmogenic substate involves a large mass of myocardium.