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Biomedical subjects

W Feldman

Publications and source records attributed to W Feldman.

At least 37 records · Page 2Linked to original sources
PubMed1996

Positional sequencing by hybridization.

Sequencing by hybridization (SBH) is a promising alternative to the classical DNA sequencing approaches. However, the resolving power of SBH is rather low: with 64kb sequencing chips, unknown DNA fragments only as long as 200 bp can be reconstructed in a single SBH experiment. To improve the resolving power of SBH, positional SBH (PSBH) has recently been suggested; this allows (with additional experimental work) approximate positions of every l-tuple in a target DNA fragment to be measured. We study the positional Eulerian path problem motivated by PSBH. The input to the positional eulerian path problem is an Eulerian graph G(V, E) in which every edge has an associated range of integers and the problem is to find an Eulerian path e1,...,e/E/ in G such that the range of ei contains i. We show that the positional Eulerian path problem is NP-complete even when the maximum out-degree (in-degree) of any vertex in the graph is 2. On a positive note we present polynomial algorithms to solve a special case of PSBH (bounded PSBH), where the range of the allowed positions for any edge is bounded by a constant (it corresponds to accurate experimental measurements of positions in PSBH). Moreover, if the positions of every l-tuple in an unknown DNA fragment of length n are measured with O(log n) error, then our algorithm runs in polynomial time. We also present an estimate of the resolving power of PSBH for a more realistic case when positions are measured with theta (n) error.

Algorithms↗
PubMed1996

A cohort study on childhood asthma admissions and readmissions.

BACKGROUND: Admissions to hospitals for childhood asthma seem to be increasing, even though admissions for other childhood conditions are decreasing. We studied admissions and readmissions for childhood asthma in Ontario in an attempt to uncover factors relating to the admission patterns. METHODS: Using the hospital discharge data from the Canadian Institute for Health Information, 28,646 children with diagnoses of asthma were identified from April 1, 1989, to March 31, 1992. RESULTS: The admission rates for asthma among children in Ontario showed a 14.8% decrease from 1987 to 1992. This decline was observed primarily in 5- to 17-year-olds. Younger children had a fourfold risk of hospital admission for asthma. In the 4 years studied, 10,427 children (36.4%) were readmitted at least once, representing 22,114 readmissions, 16,196 (73.2%) of which were for asthma. The 6-month probabilities of readmission for asthma were 20.0% (0- to 4-year-olds) and 11.7% (5- to 17-year-olds). The estimated relative risks (RRs) indicated that younger children had a significantly higher risk of readmission for asthma (RR, 1.38; 95% confidence interval, 1.30 to 1.46) or asthma-related causes (RR, 5.02; 95% confidence interval, 4.16 to 6.05). CONCLUSIONS: The observed increasing trend in admissions for asthma among children in the 1970s and 1980s leveled off in the early 1990s. The declining admission rates were largely caused by the lower admission rates among school-aged children from 5 to 17 years. The relatively high admission and readmission rates of preschool children are still a concern. Further research is necessary to examine factors that influence admissions for asthma among young children.

Adolescent↗
PubMed1995

Helicobacter pylori, gastroduodenal disease, and recurrent abdominal pain in children.

OBJECTIVE: To assess the evidence for a cause-and-effect relationship between Helicobacter pylori infection and antral gastritis, peptic ulcer disease, and recurrent abdominal pain in children. DATA SOURCES: A MEDLINE search from January 1983 through July 1994 was used to identify pertinent English-language publications. Current Contents and selected specialty journals were searched manually. Editorials, reviews, case reports, abstracts, and letters to the editor were excluded. STUDY SELECTION: All studies in children (ie, 0 to 18 years) were included. DATA EXTRACTION: Hill's criteria for causal inference were used to determine the strength of the evidence for a causal relationship. DATA SYNTHESIS: In total, 45 studies (case series, cross-sectional surveys, and treatment trials) were retrieved. The rate ratio of antral gastritis in children with H pylori infection (compared with uninfected children) ranged from 1.9 to 71.0 (median, 4.6). The prevalence of H pylori infection in children with duodenal ulcer was high (range, 33% to 100%; median, 92%) compared with children with gastric ulcer (range, 11% to 75%; median, 25%). Prevalence rates of infection in children with recurrent abdominal pain were inconsistent (range, 0% to 81%; median, 22%), with lower rates in children meeting Apley's criteria (range, 0% to 9%; median, 6%). CONCLUSIONS: There is strong evidence for an association between H pylori infection and antral gastritis and duodenal ulcer disease in children; however, data from randomized, double-blind, placebo-controlled treatment trials are required. There is weak evidence for an association with gastric ulcer and weak or no evidence for an association with recurrent abdominal pain.

Abdominal Pain↗
PubMed1994

Gray code masks for sequencing by hybridization.

In light-directed synthesis of high-density oligonucleotide arrays for sequencing by hybridization, synthesis errors result from the unintended illumination of chip regions that should remain dark. Most synthesis errors occur at the borders of illuminated regions, where light diffraction, internal reflection, and scattering produce the most unintended illumination. A combinatorial synthesis strategy based on two-dimensional Gray codes was devised to reduce the overall lengths of these borders in masks for photolithographic chip design. This article describes an application of two-dimensional Gray codes and demonstrates that masks based on this approach are optimal for minimizing the border length in VLSIPS (very large scale immobilized polymer synthesis).

Algorithms↗
PubMed1994

Management of moderate head injury in childhood: degree of consensus among Canadian pediatric emergency physicians.

The purpose of this study was to assess the degree of consensus among Canadian pediatric emergency physicians regarding the management of moderate head injury in children. A questionnaire regarding the management of moderate head injury in a child was developed, and it concentrated on indications for admission and policies regarding skull radiograph. The questionnaire was given to all pediatricians who are members of the Emergency Section of the Canadian Pediatric Society (n = 33) and who represent 15 Canadian pediatric emergency departments. The outcome was measured by the degree of consensus regarding management of children with moderate head injury. Twenty-three of 33 (70%) questionnaires, representing 14 of 15 (93%) emergency departments, were returned. Only five of 23 (22%) questionnaires report routinely admitting otherwise well children with short (three minutes or less) loss of consciousness; five (22%) routinely order a skull radiograph - three (13%) routinely do both. Certain clinical indicators led to 70 to 80% agreement regarding admission: severe headache, seizures, depressed skull fracture, and persistent vomiting. Agreement of more than 70% regarding indications for ordering a skull radiograph was achieved only for clinical suspicion of a depressed skull fracture. In conclusion, for the average child who is well after a loss of consciousness after a head injury lasting three minutes or less, the majority of respondents do not routinely admit the child or order a routine skull radiograph. A reasonable degree of consensus (70-80%) regarding ordering of skull radiographs and admission is based on clinical criteria.

Canada↗
PubMed1994

Do child and/or parent bereavement programs work?

Bereavement programs for children and parents are becoming popular since there are more and more neonatal intensive care programs, pediatric oncology programs and pediatric intensive care programs offering these services. This paper addresses the following question: Do bereavement programs work? An overview of the literature dating back to 1964 was undertaken. Only papers dealing with treatment were reviewed. Randomized controlled trials were selected as presenting the best evidence for or against program effectiveness. Methodologic features such as description of the sample, comparability of treatment and control groups, description of the intervention, use of objective, valid, reproducible and blinded outcome measures, sample size calculations, thoroughness of follow-up and attention to clinical as well as statistical significance were assessed. Four randomized controlled trials were found in the literature search. Two of the studies showed benefit, two did not. All four suffered significant methodologic flaws. At this time it is unclear as to whether or not bereavement programs help families. Given the high costs of health care, it is important that studies be done to determine which families are likely to benefit from bereavement programs and what type of program is effective.

Adaptation, Psychological↗
PubMed1993

Over-the-counter cold medications. A critical review of clinical trials between 1950 and 1991.

OBJECTIVE: To determine whether over-the-counter cold medications have been shown to be effective in relieving symptoms in children, adolescents, and adults. DATA SOURCES: The MEDLINE database using the key words combined with medications and research and review articles. Articles were retrieved if they were written in English and published between January 1950 and January 1991. STUDY SELECTION: Articles were selected if they described a controlled clinical trial on the treatment of the common cold. Forty-eight percent of 106 articles met the selection criteria, and these were grouped by age into child studies (< 5 years old and < 12 years old) and adolescent (aged 12 years and older)/adult studies. DATA EXTRACTION: Each article was scored on 11 criteria to determine scientific validity. Those articles scoring above 70% were included in the final analysis. Two authors independently scored a sample of articles to determine interrater reliability. DATA SYNTHESIS: Very few studies have been performed on children. Of those, two done on preschool children demonstrated no symptom relief, whereas two done on older children showed some benefit. In the adolescent/adult studies, chlorpheniramine maleate, pseudoephedrine hydrochloride, oxymetazoline hydrochloride, phenylpropanolamine hydrochloride, ipratropium bromide, and atropine methonitrate all improved nasal symptoms. Combination therapy (using an antihistamine-decongestant mix) was shown to relieve a variety of symptoms. CONCLUSIONS: No good evidence has demonstrated the effectiveness of over-the-counter cold medications in preschool children. Further studies are required to clarify the role of these medications in children. Certain single over-the-counter medications and combinations have been shown to reduce cold symptoms in adolescents and adults.

Adolescent↗
PubMed1993

Comparison of CNS adverse effects between astemizole and chlorpheniramine in children: a randomized, double-blind study.

OBJECTIVE: To assess the central nervous system side effects of chlorpheniramine and astemizole in children. DESIGN: Prospective, randomized, double-blind cross-over study. SETTING: Children were recruited from the out-patient allergy clinic and from respondents to an advertisement in a local newspaper. The study was conducted in the outpatient clinics of the ambulatory care services of the Children's Hospital of Eastern Ontario. PATIENTS, PARTICIPANTS: Children 8-16 years of age, with isolated allergic rhinitis or hay fever, were eligible for the study. We excluded children with: (1) chronic conditions (specifically asthma, atopic dermatitis, learning disabilities, or current treatment with oral corticosteroid medication); (2) known allergy to the study medications; (3) recent use of any antihistamine medication. One hundred and three children entered the study and 92 completed it. INTERVENTIONS: Children were stratified by age and randomly allocated to treatment with one of the two medication sequences. Over a period of 13 weeks both groups had 1 week of baseline studies, 3 weeks of one study medication, either chlorpheniramine or astemizole, a 6-week wash-out period and then 3 weeks of the other study medication for a second treatment period. MAIN OUTCOME MEASURES: Attention span (continuous performance test), short-term auditory and visual memory (visual aural digit span test), visual memory for geometric shapes (Benton visual retention test), motor coordination and visual-motor integration (grooved pegboard test), tapping speed and fine motor coordination (finger tapping test), physical side effects (such as sleepiness and dizziness), and compliance. RESULTS: One hundred and three patients were enrolled in the study, 92 (89%) completed the study. There were no significant drug effects on the visual retention test and the continuous performance test. On the visual aural digit span test, patients treated with astemizole scored higher than at baseline. There were no clinical or statistical differences in adverse effects between the two medications or between each medication and baseline. CONCLUSIONS: The two antihistamines studied had no adverse effects on the performance of children.

Adolescent↗
PubMed1992

Nonfatal childhood injuries: a survey at the Children's Hospital of eastern Ontario.

OBJECTIVE: To examine the types and severity of injuries seen in the Emergency Department of the Children's Hospital of Eastern Ontario and the circumstances surrounding the events. DESIGN: Chart review. SETTING: A tertiary care hospital that serves a child population of 600,000 in eastern Ontario and western Quebec. PARTICIPANTS: Every sixth day's charts of children up to 17 years of age who visited the Emergency Department because of injuries between Sept. 1, 1984, and Aug. 31, 1985, were examined retrospectively. RESULTS: A total of 2886 charts were reviewed. There were more boys than girls. Most (1354 [46.9%]) of the accidents had occurred at home. Falls and sports-related accidents were the leading causes of injury (in 1088 [37.7%] and 560 [19.4%] of the cases respectively). Most of the visits were for minor injuries (bumps, swellings, cuts, bruises and scrapes), and only 114 (4.0%) of the children were admitted to the hospital. Injuries from motor vehicle accidents accounted for the highest admission rate (17.4%). Important information regarding the circumstances surrounding the events (e.g., whether a seat belt or car seat was used) was frequently missing from the charts. CONCLUSIONS: Nonfatal injuries are common, especially in or around the home, and remain a significant problem in our society in terms of radiographic and consulting fees, time off from school or work and pain. Given the difficulties in obtaining information on the circumstances surrounding the events prospective studies are needed. Factors related to the occurrence and severity of childhood injury and whether these factors can be altered remain a high priority for research.

Accidental Falls↗
PubMed1992

Evaluation of renal scars by technetium-labeled dimercaptosuccinic acid scan, intravenous urography, and ultrasonography: a comparative study.

The objective of our prospective study was to compare the sensitivity and specificity of ultrasonography, intravenous pyelography, and dimercaptosuccinic acid scan in detecting scarred kidneys. Twenty-seven consecutive subjects with recurrent urinary tract infections, vesicoureteral reflux, scarred kidneys, or a combination of these problems had all three imaging procedures performed. With the total number of scars serving as the gold standard, the sensitivity (94%) and specificity (100%) in identifying renal scars in children were highest for the DMSA scan. Intraobserver (95%) and interobserver (90%) reliability were also high for the DMSA scan. However, the clinical interpretation of the increased sensitivity of the DMSA scan is unknown. Changes on the scan not identified by intravenous urography may not represent true scars. Research into the long-term significance of these scars is indicated.

Adolescent↗
PubMed1992

Central nervous system side-effects of antihistamines in schoolchildren.

There are no studies available in the literature on the effects of classical antihistamines on the central nervous system (CNS) in children. Clinical studies indicate that somnolence occurs more often with classical antihistamines than with placebo. There is no difference in inducing somnolence in children between placebo and astemizole or terfenadine, two new antihistamines that have thoroughly been shown to have no sedative effect greater than placebo in adults. A double-blind, cross-over trial investigating the CNS-effects of astemizole and chlorpheniramine in schoolchildren failed to show a negative effect of either of these drugs on performance.

Astemizole↗
PubMed1991

Serious childhood injuries caused by air guns.

OBJECTIVE: To determine the severity of nonfatal injuries to children caused by air guns and pellet guns. DESIGN: Case series (hospital chart review). SETTING: Inpatient wards of the Children's Hospital of Eastern Ontario. PATIENTS: All children under 18 years of age admitted to the hospital from Jan. 1, 1979, to Dec. 31, 1989, under ICD code E917, E922, E955, E965, E970 or E985 who had suffered air gun injuries. MAIN OUTCOME MEASURES: Personal data, circumstances of event and clinical data. RESULTS: The 43 children (37 boys) had a median age of 12 years. The circumstances of the accident were known in 20 cases: 17 children were playing and 3 were cleaning the gun when it went off. Four children thought the gun was unloaded. In five cases the bullet ricocheted into the eye. Nine injuries were self-inflicted. Injury was to the extremities in 21 (49%), the eyes in 15 (35%) and the head and neck in 7 (16%). The median length of hospital stay was 4 days. Six children had long-term disabilities, all the result of eye injuries; two had cataract surgery, and four required enucleation of the eye. CONCLUSIONS: Air guns can cause serious injury to children. Their sale needs to be banned or at least carefully regulated.

Adolescent↗
PubMed1991

Effect of therapeutic plasma concentrations of theophylline on behavior, cognitive processing, and affect in children with asthma.

A double-blind, randomized, crossover study assessed the effects of theophylline on behavior, mood, and efficiency of cognitive processing. Thirty-one children aged 8 to 12 years with moderate asthma were randomly assigned to 10-day theophylline followed by placebo or to placebo followed by theophylline experimental conditions separated by 2-day washout periods. Theophylline plasma concentrations and pulmonary function tests were performed throughout the study. Cognitive functioning tests and self-report measures were administered at baseline and after each medication phase. Behavior ratings were obtained from parents and teachers. Parents' and teachers' ratings did not reflect a theophylline effect on attention or activity level; children's self-reports showed no changes in mood, and no statistically significant differences were found on measures of cognitive processing. Large individual differences in sensitivity to theophylline effects were present. Although most of the children tolerated theophylline well, those already having attentional or achievement problems appeared vulnerable to adverse effects. Individual response differences should be a focus of future studies.

Affect↗
PubMed1991

Randomized, controlled trial comparing long-term sulfonamide therapy to ventilation tubes for otitis media with effusion.

Several studies have indicated that either the surgical insertion of ventilation tubes (VTs) or long-term treatment with sulfonamide-based antibacterials is effective in the management of otitis media with effusion (OME; otherwise known as serous otitis media, secretory otitis media, and glue ear) when compared with a no-treatment control or placebo. This controlled trial is the first to compare directly the effectiveness of these two treatments for long-standing OME. Outcome variables are treatment success rates, hearing thresholds, recurrent acute otitis media episodes, and side effects of medication or complications of VT placement. One hundred twenty-five children (aged 2.5 to 7 years) who met the usual indications for surgery (long-standing [greater than 3 months] OME and conductive hearing loss) were randomly assigned to "medical" treatment (sulfisoxazole 75 mg/kg per day for 6 months) or "surgical" treatment (bilateral insertion of VTs). Subjects underwent pure-tone audiometry (500, 1000, 2000, 4000 Hz) and otomicroscopic examination at 2, 4, 6, 12, and 18 months. A significantly greater proportion of medical subjects (67%) than surgical subjects (48%) were treatment failures at 6, 12, or 18 months (P = .0208). Surgical subjects had significantly better hearing at 2 and 4 months (P values less than .01) but not at 6, 12, and 18 months (P values greater than .2). A significantly greater proportion of surgical subjects (50%) experienced complications of treatment than did medical subjects (9%) (P less than .001). Thirty-three percent of candidates for VT placement did not require surgery when treated with a 6-month course of sulfisoxazole.(ABSTRACT TRUNCATED AT 250 WORDS)

Audiometry, Pure-Tone↗
PubMed1991

Is childhood sexual abuse really increasing in prevalence? An analysis of the evidence.

One controversy regarding childhood sexual abuse is whether the increased rate of reported cases reflects a true increase in prevalence. In this report, data obtained in the 1970s and 1980s were compared with those of the 1940s. Using predetermined criteria for quality of information, commonality of definitions of childhood sexual abuse, and research design, the authors reviewed the Kinsey report published in 1953 and 19 prevalence studies reported in the last 10 years. Interrater reliability was .97 for each paper. In spite of differences in study designs and populations surveyed, where definitions of childhood sexual abuse were similar, the more recent studies with the strongest methodology reported prevalence figures similar to those of Kinsey in the 1940s, ie, 10% to 12% of girls younger than 14 years of age. Thus it would appear that increased reporting is due to changes in legislation and social climate rather than a true increase in prevalence. The absence of an increase in prevalence of childhood sexual abuse should not deter those interested in pursuing solid research in prevention and treatment because any childhood sexual abuse is too much.

Adolescent↗
PubMed1990

Twice-daily antibiotics in the treatment of acute otitis media: trimethoprim-sulfamethoxazole versus amoxicillin-clavulanate.

Twice-daily trimethoprim-sulfamethoxazole has been shown to be effective in the treatment of acute otitis media except that caused by group A beta-streptococci. Amoxicillin-clavulanate potassium is effective in vitro against all bacterial pathogens causing acute otitis media and has been reported to be effective when given twice daily for urinary tract infections, acute otitis media and respiratory tract infections. To determine whether the in-vitro efficacy of amoxicillin-clavulanate carries over clinically, we conducted a prospective randomized double-blind trial in 219 children presenting at a pediatric walk-in clinic. Diagnosis and follow-up assessments were made by means of examination of the tympanic membrane and acoustic otoscopy. Of the 219 children 202 (101 in either group) were assessed by a specially trained nurse at a follow-up visit 12 to 16 (mean 14) days after treatment was begun. Cure was defined as absence of symptoms and normal results of both visual inspection of the tympanic membrane and acoustic reflectometry; improvement was defined as absence of symptoms and either normal appearance of the tympanic membrane or normal results of acoustic reflectometry; treatment failure was defined as abnormal appearance of the tympanic membrane along with an acoustic reflectometry reading of 5 units or more. There were no differences in age (mean 60 months), sex or proportion of subjects with unilateral versus bilateral disease between the two groups. The combined rate of cure an improvement was significantly higher with trimethoprim-sulfamethoxazole (93%) than with amoxicillin-clavulanate (82%) (p = 0.03). The rate of compliance (more than 80% of the drug taken) did not differ significantly between the two groups. Gastrointestinal side effects were more common with amoxicillin-clavulanate (p less than 0.0001). Our results suggest that for acute otitis media twice-daily trimethoprim-sulfamethoxazole is more effective clinically and produces fewer side effects than twice-daily amoxicillin-clavulanate.

Acoustic Impedance Tests↗