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Biomedical subjects

Chris Harris

Publications and source records attributed to Chris Harris.

11 recordsLinked to original sources
PubMed2006

Safety of electronic apex locators and pulp testers in patients with implanted cardiac pacemakers or cardioverter/defibrillators.

The purpose of this study was to determine if electronic apex locators (EAL) or electric pulp testers (EPT) interfere with the function of implanted cardiac pacemakers (ICP) or cardioverter/defibrillators (ICD). Twenty-seven patients with ICPs or ICDs had continuous electrocardiogram monitoring and device interrogation to detect interferences during the use of two types of EALs and one EPT. No interferences were detected by any ICP or ICD. In six patients, with intermittent pacing, a significant increase in pacing was observed during EAL/EPT stimulation (p < 0.05). Examination of RR intervals (a measure of intrinsic heart rate) demonstrated significantly longer RR intervals (slower intrinsic heart rate) during EAL/EPT stimulation (p < 0.05). Evaluation of the electrocardiograms for each patient failed to show any abnormalities in pacing during testing. These findings led us to conclude that the increased pacing frequency observed was related to a slower intrinsic heart rate and not electrical interference with the cardiac devices. In conclusion, the two EALs and one EPT used in this study did not interfere with the functioning of any of the cardiac devices tested.

Analysis of Variance↗
PubMed2006

Non-eating disorders psychopathology in children and adolescents with eating disorders: implications for malnutrition and symptom severity.

OBJECTIVES: To compare the general psychopathology in an eating disorders (ED) and a child mental health outpatient sample and investigate the implications of comorbidity on psychological and physical measures of ED severity. METHODS: One hundred thirty-six children and adolescents with a DSM-IV ED diagnosis were compared with age- and gender-matched controls. Measures included the Eating Disorders Examination and the Child Behavior Checklist. RESULTS: The ED group had lower general and externalizing psychopathology scores and no difference in internalizing (anxiety-depression) symptoms. Of the anorexia nervosa group, 49% experienced comorbid psychopathology. This group had significantly higher ED psychopathology, longer duration of illness, and more gastrointestinal symptoms, but no difference in malnutrition status. Eating disorders not otherwise specified (EDNos) group measures were less influenced by comorbidity status. CONCLUSIONS: Anxiety-depressive symptoms are very common in children and adolescents with EDs. Comorbidity status influences illness severity, especially in the anorexia nervosa group. The management implications of these findings are discussed.

Adolescent↗
PubMed2004

The apnea test for brain death determination: an alternative approach.

INTRODUCTION: Problems associated with the standard apnea test relate to overshooting or undershooting the target PaCO2, potentially compromising the viability of organs for transplantation or invalidating the test. MATERIALS AND METHODS: In 60 adult patients, the authors used an alternative method using exogenously administered CO2 and measurement of end-tidal CO2. RESULTS: All patients achieved an adequate respiratory stimulus (mean increase in PaCO2 was 28+/-3 mmHg, postapnea test pH was 7.20+/-.02). There was a clinically insignificant reduction in arterial blood pressure during testing, but no other complications occurred. Multiple regression analysis demonstrated a correlation between the predicted PaCO2 (predicted from the end-tidal CO2) and measured PaCO2 (64+/-9 versus 67+/-9; r=.75169, p<0.0001). CONCLUSION: Exogenously administered CO2 as an alternative method for the standard apnea test was a reliable and safe method, with minimal complications that offers several advantages over the standard method.

Adolescent↗
PubMed2003

Translaryngeal tracheostomy: experience of 340 cases.

OBJECTIVE: To describe the authors' initial experience with a new and innovative dilational translaryngeal tracheostomy bedside technique. STUDY DESIGN: A prospective documentation of 340 patients who received an elective translaryngeal tracheostomy in a multidisciplinary, tertiary care intensive care unit during a 45-month period. RESULTS: All translaryngeal tracheostomy procedures but one were completed successfully; one was aborted because of bleeding from a thyroid vein. Minor perioperative complications occurred in 42% of patients, which caused no adverse effects. The most common complication was arterial desaturation occurring in 17% of patients; this was short-lived, and the lowest saturation was 79%. Blood loss was minimal (<5 mL) in all but one case, despite an elevated international normalized ratio (INR) and partial thromboplastin time in 42% and 41% of patients, respectively, and a low platelet count in 13% of patients. CONCLUSIONS: Translaryngeal tracheostomy is a safe and reliable technique and can also be used in patients with unstable cervical spines and bleeding diathesis. It has become the authors' procedure of choice for an elective bedside tracheostomy in the intensive care unit.

Documentation↗
PubMed2003

Unusual side effects of lamotrigine therapy.

An 8-year-old boy developed tremor, unsteadiness, chorea, and eye movement abnormalities on starting lamotrigine for myoclonic jerks. Investigations for a neurodegenerative disorder were negative. Symptoms and signs resolved on stopping lamotrigine. He was well and asymptomatic on follow-up after 4 years. Another 7-year-old boy who started on lamotrigine for suspected absence seizures developed abnormalities of eye movement with associated cognitive decline, which also resolved on discontinuing the medication. Eye movement abnormalities, involuntary movements, and behavioral changes appear to be unusual side effects of lamotrigine therapy.

Anticonvulsants↗
PubMed2002

Gene discovery and microarray analysis of cacao (Theobroma cacao L.) varieties.

The cacao bean harvest from the relatively under developed tropical tree cacao (Theobroma cacao L.) is subject to high losses in potential production due to pests and diseases. To discover and understand the stability of putative natural resistance mechanisms in this commodity crop, essential for chocolate production, we undertook a gene-discovery program and demonstrated its use in gene-expression arrays. Sequencing and assembling bean and leaf cDNA library inserts produced a unique contig set of 1,380 members. High-quality annotation of this gene set using Blast and MetaFam produced annotation for 75% of the contigs and allowed us to identify the types of gene expressed in cacao beans and leaves. Microarrays were constructed using amplified inserts of the uni-gene set and challenged with bean and leaf RNA from five cacao varieties. The microarray performed well across the five randomly chosen cacao genotypes and did not show a bias towards either leaf or bean tissues. This demonstrates that the gene sequences are useful for microarray analysis across cacao genotypes and tissue types. The array results, when compared with real-time PCR results for selected genes, showed a correlation with differential gene-expression patterns. We intend that the resultant DNA sequences and molecular microarray platform will help the cacao community to understand the basis, likely stability and pathotype resistance range of candidate cacao plants.

Cacao↗
PubMed2002

Individual psychotherapy for children and adolescents with an eating disorder from historical precedent toward evidence-based practice.

This article reviews the place of individual therapy in the suite of treatment services required by children and adolescents with an eating disorder. Individual therapy is defined and traced from historical origins in psychoanalytic practice with later important modifications by Hilda Bruch and Arthur Crisp. More recent developments, based primarily on cognitive and learning theory are discussed, as is the timing of individual therapy with respect to illness stage and patient motivation. Evidence for therapy effectiveness is reviewed where possible. At present, treatment evidence in the pediatric mental health field must be inferred from adult research.

Adolescent↗
PubMedDate not supplied

A developmental model of infantile nystagmus.

The possibility that infantile nystagmus (IN) may reflect a failure in early sensorimotor integration has been proposed for more than a century, but is only recently being borne out in animal studies. The underlying neural and genetic substrate for this plasticity is complex. We propose that, in most cases, IN develops as a developmental response to reduced contrast sensitivity to high-spatial frequencies in an early "critical period," however caused, whether by structural malformations (e.g. foveal hypoplasia) or poor optics (e.g. cataract). As shown by psychophysics, contrast sensitivity to low spatial frequencies is enhanced by motion of the image across the retina. Based on our previous theoretical study (Harris & Berry, Nonlinear Dynamics, 2006), we argue that the best compromise between moving the image and maintaining the image near the fovea (or its remnant) is to oscillate the eyes with jerk nystagmus with increasing velocity waveforms, as seen empirically. The generation of jerk waveforms relies heavily on the saccadic system, which is immature in infancy. Pendular waveforms may therefore provide an alternative to jerk waveforms, and may explain why they are seen more often in young infants. We discuss the implications of this developmental model for the need to synchronize sensory and motor developments in normal development. Failure of this synchronization may also explain some idiopathic cases.

Eye Movements↗