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Biomedical subjects

D Stephens

Publications and source records attributed to D Stephens.

At least 91 records · Page 5Linked to original sources
PubMed1998

Variation in the measurements of basement membrane thickness and inflammatory cell number in bronchial biopsies.

We do not have an estimate of how much tissue is needed for a reliable measure of bronchial epithelial reticular basement membrane (RBM) thickness or for counts of inflammatory cells. An assessment of the frequency distribution and variance of data from repeat measurements of RBM thickness and biopsy section inflammatory cell counts in cases with asthma (n=6), chronic obstructive pulmonary disease (COPD; n=5), and normal healthy subjects (n=7) was made. Tissue sections were stained with haematoxylin and eosin or by immunohistochemistry for EG2, mast cell tryptase and CD3-positive cells. Measurements of RBM thickness in individuals followed a log-normal distribution. For a precision of approximately +/-15%, 31-45 measurements were required. In contrast, inflammatory cell counts for each individual did not follow a normal distribution. There was high variance such that the cumulative weighted mean did not become stable until at least 5-10 mm of tissue underlying the RBM had been included. In conclusion multiple measurements of reticular basement membrane thickness or tissue section cell counts should be made for each individual in studies of bronchial biopsies. It is recommended that reticular basement membrane thickness should be measured at 20 mm intervals over a 1 mm reticular basement membrane length and that a zone beneath it of at least 5-10 mm of reticular basement membrane should be included for counts of inflammatory cells.

Adult↗
PubMed1998

Particle size determination of a flocculated suspension using a light-scattering particle size analyzer.

Microscopy is a useful and direct method for measuring the particle size of a suspension because, in addition to the particle size and size distribution, it provides visual detection of the shape and state of aggregation of the particles in the suspension. However, this method suffers from the shortcomings of being tedious and time consuming. In this study, a light-scattering particle size analyzer was used to determine the particle size and size distribution of a flocculated suspension. The sonication of the sample prior to and during measurement was found to be critical in ensuring that data are representative of the size distribution of the primary particles of the suspension. The light-scattering results were further confirmed by data generated using a polarized light microscope equipped with an image analyzer.

Benzocaine↗
PubMed1998

Wall perimetry in chiropractic.

BACKGROUND: Wall perimetry is a method of examination that led to the initial appreciation of the "tunnel vision information." The visual field loss that wall perimetry indicates generally defines the overall characteristics of the dysfunction associated with 'tunnel vision.' Wall perimetry is an inexpensive, yet sensitive, preliminary screening test for perception abnormality in the outermost periphery of vision. OBJECTIVE: To describe wall perimetry. The term "wall perimetry" denotes a simple preliminary method of examining the visual fields of chiropractic patients. DISCUSSION: The test is described with reference to photographs. The patient stands 1 m from the corner of a room and is instructed to look directly at the junction of the walls, with the head remaining still and gaze fixed. Standing behind the patient, the examiner projects a target of light onto the wall and moves it until it is seen by the subject. CONCLUSION: Chiropractors are encouraged to test appropriate patients by wall perimetry before spinal manipulation therapy. On the basis of existing experience, detection of patients with visual field loss is to be expected. From that point, formal examination of the visual fields using kinetic or static perimetry apparatus is recommended to further verify the "tunnel vision" discovery.

Chiropractic↗
PubMed1998

Tunnel vision information: a paradox of ethics, economics, politics and science.

BACKGROUND: Improvement in vision with spinal manipulation was first observed in the early 1970s. Reports of the phenomenon appeared in the 1980s in the popular press and at scientific meetings, but it was not until the mid-1990s that general discussion of the potential value of this knowledge occurred. Considering the far-reaching implications of the possible ability to improve brain function by spinal manipulation, the delay in consideration and implementation of this concept is a paradox in general terms and a total mystery in the case of the chiropractic profession. OBJECTIVE: To provide explanations for the delay in scientific assessment of the discovery that vision improves, in appropriate patients, when the spine is manipulated and to discuss the implications of this finding. This discovery is now called the "tunnel vision information." DISCUSSION: A schema of pathological hierarchy is depicted in which the level of intervention of spinal manipulation outranks other forms of treatment. The significance of this precedence is portrayed. Possible reasons for the failure to address this hierarchy in light of the tunnel vision information are discussed with reference to established protocols, medical politics, the presentation of the data, the failure of scientific editorship and the illogical aspects of the illness itself. CONCLUSION: In the future, the delay from the initial observation of the tunnel vision discovery to its free discussion in scientific literature may seem incongruous, particularly if the health benefits which it augurs are realized.

Chiropractic↗
PubMed1997

Complete atrioventricular septal defects: results of repair, risk factors, and freedom from reoperation.

BACKGROUND: Several perioperative risk factors influence outcomes after repair of complete atrioventricular septal defects. This study was conducted to determine their association with perioperative mortality and need for reoperation. METHOD AND RESULTS: Between July 1982 and February 1995, 363 children underwent defect repair (median age, 8.3 months; mean, 17.4+/-1.3). Tetralogy of Fallot was present in 21 patients, double-outlet right ventricle in 4, subaortic stenosis in 8, ventricular hypoplasia in 8, coarctation in 5, atrial isomerism in 2, and other congenital anomalies in 9. Down's syndrome was present in 235 (65%). One-patch technique was applied in 99, two-patch in 243. During repair, the anterior bridging leaflet was divided in 12, the posterior bridging leaflet in 31, both leaflets in 71, and neither in 249. Left atrioventricular valve (LAVV) cleft was closed partially in 181 and completely in 112. Early mortality was 10.5%; 10-year survival, 83% (95% confidence interval, 0.79 to 0.87). At 10 years, freedom from reoperation for LAVV repair was 86%; LAVV replacement, 90%; subaortic stenosis, 95%; residual ventricular septal defect, 97%; permanent pacemaker insertion, 98%; and other types of reoperation, 95%. At the time of operation, greater age, shorter ischemic time, absence of a double-orifice LAVV, and cleft closure were found to be significant independent predictors of survival. CONCLUSIONS: Repair of atrioventricular septal defects has acceptable early and late mortality and a low incidence of reoperation. Double-orifice LAVV remains a risk factor. Repairs that include complete cleft closure may confer better survival.

Follow-Up Studies↗
PubMed1997

Dominant coloboma-microphthalmos syndrome associated with sensorineural hearing loss, hematuria, and cleft lip/palate.

Ocular colobomas and microphthalmos, isolated or as part of a syndrome, are usually sporadic and only rarely found in large families. A 4-generation family with autosomal dominant uveal coloboma and microphthalmos associated with cleft lip and palate was re-evaluated. Wide variability in expression is evident and more recently recognized manifestations include a complete spectrum of eye involvement, impairment of extraocular movement, mid-frequency sensorineural hearing loss, and hematuria. Learning difficulties requiring remedial teaching were present in one third of those affected and a neural tube defect has occurred in one presumed affected member. This family appears to present a unique phenotype, which provides an opportunity to identify a genetic locus involved in eye, ear, renal, primary palate, and brain development.

Abnormalities, Multiple↗
PubMed1997

Inhibition of HIV-1 replication using a mutated tRNALys-3 primer.

Cellular tRNALys-3 serves as the primer for reverse transcription of human immunodeficiency virus, type 1 (HIV-1). tRNALys-3 interacts directly with HIV-1 reverse transcriptase, is packaged into viral particles and anneals to the primer-binding site (PBS) of the HIV-1 genome to initiate reverse transcription. Therefore, the priming step of reverse transcription is a potential target for antiviral strategies. We have developed a mutant tRNALys-3 derivative with mutations in the PBS-binding region such that priming specificity was re-directed to the highly conserved TAR stem-loop region. This mutant tRNA retains high-affinity binding to HIV-1 reverse transcriptase, viral encapsidation, and is able to prime at both the targeted TAR sequence and at the viral PBS. Constitutive expression of mutant tRNA in T-cells results in marked inhibition of HIV-1 replication, as determined by measurements of viral infectivity, syncytium formation, and p24 production. Inhibition of retroviral replication through interference with the normal process of priming constitutes a new anti-retroviral approach and also provides a novel tool for dissecting molecular aspects of priming.

Base Sequence↗
PubMed1997

Hospitalization patterns in severe acute asthma in children.

We set out to determine associations between hospitalization and disease severity before and 2 hours after initiation of asthma therapy in the Emergency Department, and to describe the outcome of patients admitted and discharged. This is a retrospective review of data and charts from a randomized, double blind, placebo-controlled trial (R.C.T.) of 120 asthmatics 5-17 years of age with baseline forced expiratory volume in 1 second (FEV1) < 50% predicted, treated with 3 or 1 or 0 doses of nebulized ipratropium added to three albuterol nebulizations administered over 1 hour. None of the clinical parameters measured at baseline were associated with hospitalization. However, by 2 hours after initiation of therapy, both the FEV1 percent of predicted values (% pred.) and the total asthma score were associated with likelihood of hospital admission. Baseline O2 saturation < 92% indicated a longer hospital stay (75.3 +/- 51 hours vs. 43.0 +/- 24.4 hours, P = 0.015) and a later onset of infrequent nebulizations (46.7 +/- 35.1 vs. 26.6 +/- 17.4 hours, P = 0.006). By 2 hours, those with a post-treatment FEV1 % pred < or = 30% and an asthma score > or = 6 of 9 had a high likelihood of hospitalization (86 and 80%, respectively, combined probability 100%), whereas FEV1 % pred > or = 60% and total asthma score < 3 were associated with successful discharge (probability of 92 and 83%, respectively). We conclude that pre-treatment assessments were not associated with hospitalization, while patients with post-treatment FEV1 % pred < or = 30% and a score > or = 6 had high likelihood of hospitalization.

Administration, Inhalation↗
PubMed1997

Economic evaluation of respiratory syncytial virus infection in Canadian children: a Pediatric Investigators Collaborative Network on Infections in Canada (PICNIC) study.

OBJECTIVES: To quantify the cost and distribution of health care resources consumed annually in management of Canadian children from birth to 4 years of age with respiratory syncytial virus (RSV) infection. STUDY DESIGN: Estimates of direct medical expenditures (in 1993 U.S. dollars) were collected from a prospective cohort study of hospitalized children with RSV and from national and provincial databases. RESULTS: The annual cost of RSV-associated illness was almost $18 million. The largest component of direct expenditures (62%) was for inpatient care for the estimated 0.7% of all infected children ill enough to require admission. Physician fees comprised only 4% of inpatient expenses. Expenditures for ambulatory patients accounted for 38% of direct costs. CONCLUSIONS: The greatest reductions in the economic cost of RSV infections will be found in interventions that reduce duration of or prevent hospital stay. Costs for management of RSV infection in children in the Canadian health care system are considerably less than charges reported in the United States.

Absenteeism↗
PubMed1997

Effectiveness of prophylactic inhaled steroids in childhood asthma: a systemic review of the literature.

BACKGROUND: There has been no systematic appraisal of the evidence regarding the effectiveness of prophylactic inhaled steroids in childhood asthma. OBJECTIVE: We sought to evaluate the effectiveness of prophylactic inhaled steroids in childhood asthma. METHODS: A MEDLINE search from January 1966 through December 1996 was used to identify pertinent English-language publications. All randomized, double-blind, placebo-controlled trials of prophylactic inhaled steroid therapy for childhood asthma that included data on clinical outcomes (symptom scores and concomitant drug use) or laboratory outcomes (peak expiratory flow rate) were included. RESULTS: In total, 24 of 93 studies retrieved met the inclusion criteria. The overall weighted relative improvement in mean total symptom score (inhaled steroid vs placebo) was 50% (95% confidence interval [CI]: 49%, 51%), the overall weighted relative decrease in mean concomitant beta2-agonist use (inhaled steroid vs placebo) was 37% (95% CI: 36%, 38%), and the overall weighted relative decrease in mean concomitant oral steroid use (inhaled steroid vs placebo) was 68% (95% CI: 66%, 70%). The overall weighted absolute improvement in mean peak expiratory flow rate (inhaled steroid vs placebo) was 38 L/min (95% CI: 34.3 L/min, 41.7 L/min). CONCLUSIONS: Prophylactic inhaled steroids are effective, compared with placebo, in improving both clinical and laboratory outcomes in childhood asthma.

Child↗
PubMed1997

Giuseppe Gradenigo and his contributions to audiology.

Giuseppe Gradenigo (1859-1926) was an important figure in the development of Otology. Within this paper the authors consider his background and his particular contributions to the development of various aspects of audiology.

Audiology↗
PubMed1997

Pendred syndrome--100 years of underascertainment?

Pendred syndrome is an autosomal recessive condition classically characterized by deafness and goitre. Since both cochlear and thyroid pathology are required to secure the diagnosis, it is unclear whether the condition might present without the classical features. The perchlorate discharge test, the gold-standard investigation for Pendred syndrome, is non-specific, and in the absence of alternative means of confirming the diagnosis, its sensitivity is unknown. We used the recent mapping of the gene to chromosome 7q to identify pedigrees with a likely diagnosis of Pendred syndrome, and assessed the prevalence of clinical parameters of disease in affected patients. Thirty-six familial cases showed co-segregation between disease and the Pendred syndrome locus on chromosome 7q. Clinical and investigative findings were compared in index cases (n = 18) vs. affected siblings (n = 18). The overall prevalence of goitre was 73%, higher in index cases (94%) than in siblings (56%), many of whom had not previously been considered to have the condition. One perchlorate discharge test was false-negative (2.9%). Radiological malformations of the cochlea were identified in 86% of cases. Securing a diagnosis of Pendred syndrome may be difficult, especially in the single case. The perchlorate discharge test, although valuable, is difficult to undertake in the younger patient, and radiology may assist in diagnosing such patients.

Adolescent↗
PubMed1997

A tinnitus problem questionnaire in a clinic population.

OBJECTIVE: The purpose of this study was to investigate difficulties associated with tinnitus in a large sample of patients using an open-ended problem questionnaire. DESIGN: Four hundred seventy-three unselected patients referred to the Tinnitus Clinic of the Welsh Hearing Institute (1986 through 1991) completed the Tinnitus Problem Questionnaire (Tyler & Baker, 1988). Before clinical assessment, patients were invited to list problems that they associated with their tinnitus in order of importance in an open-ended questionnaire. Their responses were coded into 45 categories. The responses of 39 patients who only described their tinnitus were excluded, leaving unselected responses from 436 patients, 224 women and 212 men, whose average age was 57.1 yr. The questionnaire elicited an average 3.78 responses per patient (range 1 to 12). RESULTS: The 30 most common difficulties attributed to tinnitus are described. There was broad agreement between the problems reported in this clinic-based study and those reported by a self-help group sample (Tyler & Baker, 1983). CONCLUSIONS: Analysis of these responses into groups based on psychological (30.1%), hearing (23.5%), health (20.7%), sleep (14.6%), and situational (11.1%) difficulties highlights the need for recognition of the global consequences of tinnitus to many patients and for a broadly based tinnitus management model.

Adolescent↗
PubMed1997

Age-related hearing loss in the dependent elderly population: a model for nursing care.

Advancing nursing care through the implementation of evidence-based practice is a legitimate professional ideal. In reality there are many complex issues that need be addressed before such a goal can be achieved. This paper takes an intermediate step towards the realization of this aim in one aspect of continuing care nursing through the presentation of a procedural model. The presented model is designed to stimulate debate as to what could be, and arguably should be the role of the nurse in relation to meeting the auditory rehabilitative needs of dependent elderly patients. The model is based upon a published management model which outlines the auditory rehabilitative process within a psychosocial framework. The original model has been modified as a result of knowledge synthesis from a range of specialist disciplines including nursing. The Audiological Care Model for Nursing is intended to offer an accessible guide to this often neglected aspect of care.

Activities of Daily Living↗
PubMed1997

Pendred syndrome: evidence for genetic homogeneity and further refinement of linkage.

Pendred syndrome is the association between congenital sensorineural deafness and goitre. The disorder is characterised by the incomplete discharge of radioiodide from a primed thyroid following perchlorate challenge. However, the molecular basis of the association between hearing loss and a defect in organification of iodide remains unclear. Pendred syndrome is inherited as an autosomal recessive trait and has recently been mapped to 7q31 coincident with the non-syndromic deafness locus DFNB4. To define the critical linkage interval for Pendred syndrome we have studied five kindreds, each with members affected by Pendred syndrome. All families support linkage to the chromosome 7 region, defined by the microsatellite markers D7S501-D7S523. Detailed haplotype analysis refines the Pendred syndrome linkage interval to a region flanked by the marker loci D7S501 and D7S525, separated by a genetic distance estimated to be 2.5 cM. As potential candidate genes have as yet not been mapped to this interval, these data will contribute to a positional cloning approach for the identification of the Pendred syndrome gene.

Adolescent↗
PubMed1997

Nosocomial respiratory syncytial virus infection in Canadian pediatric hospitals: a Pediatric Investigators Collaborative Network on Infections in Canada Study.

OBJECTIVE: To determine nosocomial transmission of respiratory syncytial virus (RSV) in Canadian pediatric hospitals, outcomes associated with nosocomial disease, and infection control practices. DESIGN: A prospective cohort study in the 1992 to 1994 winter respiratory seasons. SETTING: Nine Canadian pediatric university-affiliated hospitals. PARTICIPANTS: Hospitalized children with symptoms of lower respiratory tract infection (at least one of cough, wheezing, dyspnea, tachypnea, and apnea) and RSV antigen identified in a nasopharyngeal aspirate. RESULTS: Of 1516 children, 91 (6%) had nosocomial RSV (NRSV), defined as symptoms of lower respiratory tract infection and RSV antigen beginning >72 hours after admission. The nosocomial ratio (NRSV/[com-munity-acquired RSV {CARSV})] + NRSV) varied by site from 2.8% to 13%. The median length of stay attributable to RSV for community-acquired illness was 5 days, but 10 days for nosocomial illness. Four children with NRSV (4. 4%) died within 2 weeks of infection, compared with 6 (0.42%) with CARSV (relative risk = 10.4, 95% confidence interval: 3.0, 36.4). All sites isolated RSV-positive patients in single rooms or cohorted them. In a multivariate model, no particular isolation policy was associated with decreased nosocomial ratio, but gowning to enter the room was associated with increased risk of RSV transmission (incidence rate ratio 2.81; confidence interval: 1.65, 4.77). CONCLUSIONS: RSV transmission risk in Canadian pediatric hospitals is generally low. Although use of barrier methods varies, all sites cohort or isolate RSV-positive patients in single rooms. Children with risk factors for severe disease who acquire infection nosocomially have prolonged stays and excess mortality.

Canada↗
PubMed1997

Does ribavirin impact on the hospital course of children with respiratory syncytial virus (RSV) infection? An analysis using the pediatric investigators collaborative network on infections in Canada (PICNIC) RSV database.

OBJECTIVES: To determine the relationship between receipt of aerosolized ribavirin and the hospital course of high-risk infants and children with respiratory syncytial virus (RSV) lower respiratory infection (LRI). METHODS: The 1993-1994 Pediatric Investigators Collaborative Network on Infections in Canada (PICNIC) RSV database consists of prospectively enrolled children with acute RSV LRI, admitted to nine Canadian pediatric tertiary care centers. After excluding cases with compromised immunity and/or nosocomial infection, subsets with any congenital heart disease (CHD), chronic lung disease (CLD), age </=6 weeks (INFANT), gestation </=36 weeks (PREM), or severe disease within 48 hours of admission as shown by an oxygen saturation </=90% or an FiO2 requirement of >.35 (EARLY HYPOXIA) were studied in two ways. First, each risk group subset was analyzed separately to assess the association between ribavirin receipt and measures of disease severity including duration of intensive care, mechanical ventilation, hypoxia and RSV-attributable hospital stay. Secondly, ribavirin was added as an independent variable to a previously described multiple regression model for RSV-attributable length of hospital stay and two mutually exclusive subsets were analyzed: 1) previously healthy patients with >/=1 of: INFANT, PREM, or EARLY HYPOXIA; 2) patients with CHD and/or CLD. RESULTS: Between January 1993 and June 1994, 1425 community-acquired hospitalized cases of RSV LRI were entered into the RSV database. Among these 750 (52.6%) fit into one or more of the defined subsets including 97 CHD, 134 CLD, 213 INFANT, 211 PREM, and 463 EARLY HYPOXIA. The proportion ventilated in each group was 20.6%, 20.9%, 15.5%, 15.2%, and 13.3%, respectively. Across the subsets ribavirin use ranged from 36% to 57% of ventilated patients and 6% to 39% of nonventilated patients. For nonventilated patients in each subset the median RSV-attributable hospital length of stay (RSV-LOS) was 2 to 3 days longer for ribavirin recipients and the duration of hypoxia was significantly increased. Duration of intensive care unit (ICU) stay was also increased for all ribavirin-treated subgroups except those with CHD. In contrast, for ventilated patients, ribavirin therapy was not significantly associated with any of the outcome measures regardless of risk group. In the multiple regression model, ribavirin was significantly associated with a prolonged RSV-LOS both for children with CHD and/or CLD as well as for those whose only risk factors included INFANT, PREM, and/or EARLY HYPOXIA. CONCLUSIONS: These data raise further doubts about the clinical effectiveness of ribavirin in infants and children with risk factors for severe disease. Selection bias, with ribavirin used for sicker children, may have influenced outcome. Nevertheless the long durations of hospitalization, ICU, ventilation, and oxygen supplementation in nonventilated ribavirin recipients stress the need for further randomized trials to assess its efficacy.

Antiviral Agents↗