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Biomedical subjects

A Ross

Publications and source records attributed to A Ross.

At least 181 records · Page 10Linked to original sources
PubMed1990

Precursors of reading delay: neurodevelopmental milestones.

The relationship between current reading ability and the achievement of early language and motor developmental milestones was evaluated in 240 children, aged 7 1/2 years, whose language and motor achievement had been charted at each well baby visit during the first 2 years of life. Those children whose composite reading score was 6 months behind their chronologic age on the Woodcock-Johnson Psychoeducational Battery were classified as having reading delay. Relationships to reading outcome were assessed for individual infant milestones, for critical screening values, and by statistical techniques that characterized the developmental process rather than single milestones. Significant differences (P less than .05) were noted between children with and without reading delays for the following milestones: 4 to 6 words, 7 to 20 words, 50 words, 2-word sentences, and 5 and 8 body parts. The positive predictive value of slower milestone achievement ranged from 0% to 50%. Techniques that focused on the developmental process during the first 2 years (either rate of achievement of neurodevelopmental milestones or order of milestone acquisition) were better able to classify children with reading delay (sensitivity = .73, specificity = .78). Although the language milestone measures did not classify children sufficiently well to be diagnostic, the data served to determine whether a child would be at high risk based on performance rather than historical factors.

Child↗
PubMed1990

Stature and weight status of children in an urban kindergarten population.

To assess the prevalence of growth problems among school entrants in an urban population who were not preselected on poverty or other nutritional risk criteria, we analyzed height and weight measurements for 5170 4- and 5-year-old children (91.9% black, 5.5% white, and 2.6% Hispanic) who enrolled in District of Columbia public school kindergartens in the Fall of 1985. Compared to the National Center for Health Statistics reference, the white girls and boys were of average height, Hispanic girls were of average height, and Hispanic boys were shorter than average. The black girls and boys were taller than average. In light of published evidence for black-white differences in the timing and duration of growth, we tentatively attributed this tall stature to advanced skeletal maturation of the black children relative to the predominantly white United States population growth standards. Underweight was virtually absent in this population. Excess overweight was noted in all sex-racial/ethnic subgroups, particularly among Hispanic children. However, the extent to which overweight (high weight-for-height percentile) represents obesity in kindergarten-aged children and in different racial/ethnic groups needs clarification before the implications of the finding of excess overweight can be fully understood. Overall, the growth of these children was on a par with the National Center for Health Statistics growth reference population.

Age Factors↗
PubMed1989

Health and mental health problems of homeless men and women in Baltimore.

A study of homeless people in Baltimore, Md, focused on their health and other characteristics, with special emphasis on their needs for services. In the first stage, 298 men and 230 women were randomly selected from the missions, shelters, and jail in Baltimore to respond to a baseline interview that provided extensive sociodemographic and health-related data. In the second stage, a subsample of 203 subjects was randomly selected from the baseline survey respondents to have systematic psychiatric and physical examinations. Data are presented from both stages. Data from the first stage demonstrate, among other things, the high levels of disaffiliation of this population and their heavy involvement in substance abuse. Data from the clinical examinations demonstrate the high prevalence of mental illnesses and other psychiatric disorders and of a wide range of physical disorders and confirm the high prevalence of alcohol abuse disorders. The high rates of comorbidity of these conditions is demonstrated and data are provided on the subjects' needs for mental health and substance abuse services.

Adult↗
PubMed1989

What have we learned about coronary artery disease from high-frequency epicardial echocardiography?

We have used a high frequency epicardial echocardiographic technique to visualize and measure coronary artery lumens and walls in patients undergoing cardiac surgery. A 12 MHz probe (Surgiscan, Biosound Corp.) is sterilized and placed on the exposed epicardial coronary arteries. Transverse cross-sectional views are obtained from the arteries on the anterior surface of the heart: the right coronary artery to the cardiac margin and the left anterior descending coronary artery to the cardiac apex. Numerous echocardiographic-angiographic-pathological correlations have been obtained from this work. We have validated the echocardiographic lumen and wall measurements by comparing the echo measurements to histological material from pressure-distended coronary arterial segments (from animals and fresh human autopsy specimens). We have shown by comparison with angiography that coronary arteries which appear normal or only minimally diseased by angiograms are often diffusely and severely atherosclerotic. We have also evaluated the shape of atherosclerotic lesions and demonstrated a wide range of lumen shapes (oval, circular, complex) and location within the residual coronary lumen (eccentric vs. concentric). Highly eccentric lesions are characterized by relative preservation of portions of the arterial wall, and this may preserve vasoreactivity of the atherosclerotic vessel. We have also demonstrated remodeling of atherosclerotic lesions: enlargement of the total arterial area (wall plus lumen) as a compensatory mechanism to preserve the arterial lumen in the face of encroaching atherosclerosis. High frequency epicardial echocardiography offers an accurate, real-time, in-vivo method for the anatomic and functional evaluation of coronary atherosclerosis. This dynamic, in-vivo technique supports and extends information previously obtainable only from pathologic studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗
PubMed1989

Evaluation of blood collected on filter paper for detection of antibodies to human immunodeficiency virus type 1.

This study was undertaken to evaluate the sensitivity and specificity of a commercial enzyme immunoassay in detecting antibody to human immunodeficiency virus type 1 using whole-blood specimens collected onto filter paper. Results obtained with specimens collected onto filter paper were comparable with those obtained with the corresponding serum or plasma specimens.

Blood Specimen Collection↗
PubMed1989

Giftedness. Can it be predicted in infancy?

A cohort of 200 children, who were followed from birth and periodically evaluated as part of a longitudinal study of child development, was used to determine the ability of the Bayley Scales of Infant Development (BSID) to predict children who would be considered intellectually gifted at 7.5 years. The cohort was predominantly white (91%), upper middle class (70% in Hollingshead class 1 or 2), and had preschool educational experiences (94%). At outcome, 36 children had WISC-R verbal, performance, or full scale IQs greater than 135 and were called gifted. On average, gifted children walked 0.7 months earlier and spoke two-word sentences 2.2 months earlier than the non-gifted group. As a group, gifted children showed statistically significant, but clinically small, advantages for age of walking, age of speaking two-word sentences, BSID, and Stanford Binet IQ. Of the 36 children who later proved to be gifted, only two had BSID IQs greater than 134. Of the four children who had BSID IQs greater than 134, two maintained their superior function but 2 did not. A discriminant function analysis was used to predict giftedness for individual children based on BSID performance. The resulting classification achieved sensitivity = 0.69 and specificity = 0.39. Although groups of infants who will be gifted have higher BSID scores, the BSID cannot be endorsed as a method of identifying individual infants who will later demonstrate superior cognitive function.

Child↗
PubMed1989

Factors affecting preparation of chromosomes for scanning electron microscopy using osmium impregnation.

Osmium impregnation techniques have become useful for imparting conductivity to tissue specimens for SEM, thereby avoiding coating with gold or other metals. Such techniques have been developed to produce aesthetically pleasing images of mammalian (particularly human) chromosomes prepared by standard cytogenetical methods which use methanol-acetic acid fixation. The present study was designed: (1) to examine changes in the appearance of chromosomes as a result of preparation by osmium impregnation techniques; (2) to assess the function and importance of the various stages of chromosome preparation; and (3) to identify the chemical groups responsible for osmium binding. Methanol-acetic acid fixed chromosomes are known to have lost many proteins during fixation, and appear to be flattened down on the substrate. Osmium impregnation swells these flattened chromosomes to a variable extent, but the result is inevitably an artefact, albeit a useful one, and not a true representation of the chromosome in vivo. The size of chromatin fibres, for example, is the consequence of the degree of protein extraction during fixation, the loss of material during pre-treatments (e.g. trypsin), and the amount of osmium uptake during impregnation. Trypsin pre-treatment removes a surface coating of protein from the chromosomes as well as exposing chemical groups which can react with osmium. The principal reactive site appears to be amino groups, which bind glutaraldehyde, which in turn binds thiocarbohydrazide, to which the osmium becomes attached. Pre-treatments other than trypsin can be used to extract chromosomal material and to reveal different aspects of chromosome structure.

Animals↗
PubMed1988

Induction of phosphorylation and cell surface redistribution of acetylcholine receptors by phorbol ester and carbamylcholine in cultured chick muscle cells.

We have investigated the mechanisms regulating the clustering of nicotinic acetylcholine receptor (AChR) on the surface of cultured embryonic chick muscle cells. Treatment of these cells with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA), a potent activator of protein kinase C, was found to cause a rapid dispersal of AChR clusters, as monitored by fluorescence microscopy of cells labeled with tetramethylrhodamine-conjugated alpha-bungarotoxin. The loss of AChR clusters was not accompanied by an appreciable change in the amount of AChR on the surface of these cells, as measured by the specific binding of [125I]Bgt. Analysis of the phosphorylation pattern of immunoprecipitable AChR subunits showed that the gamma- and delta-subunits are phosphorylated by endogenous protein kinase activity in the intact muscle cells, and that the delta-subunit displays increased phosphorylation in response to TPA. Structural analogues of TPA which do not stimulate protein kinase C have no effect on AChR surface topography or phosphorylation. Exposure of chick myotubes to the cholinergic agonist carbamylcholine was found to cause a dispersal of AChR clusters with a time course similar to that of TPA. Like TPA, carbamylcholine enhances the phosphorylation of the delta-subunit of AChR. The carbamylcholine-induced redistribution and phosphorylation of AChR is blocked by the nicotinic AChR antagonist d-tubocurarine. TPA and carbamylcholine have no effect on cell morphology during the time-course of these experiments. These findings indicate that cell surface topography of AChR may be regulated by phosphorylation of its subunits and suggest a mechanism for dispersal of AChR clusters by agonist activation.

Animals↗
PubMed1988

Satisfaction and job stress in general practice.

This paper investigates sources of job satisfaction and dissatisfaction in general practice and identifies pressures and difficulties experienced by general practitioners in their work. The study revealed widespread job satisfaction based on three separate (but independent) aspects of general practice: clinical, psychosocial or managerial. Despite this, significant pressures were experienced and, in common with previous studies over the last 20 years, this research found continuing problems affecting young general practitioners in particular. The main pressures currently experienced were uncertainty and insecurity about work, isolation, poor relationships with other doctors, disillusion with the role of the general practitioner, and an awareness of changing demands. These pressures were related to experience in general practice, amount of study leave and practice organization. Like previous studies, it also appears from this research that continuing education could play an important role in attenuating these difficulties. It is argued that the emphasis should be on developing support, confidence and better contacts between general practitioners, as well as teaching knowledge and skills.

Attitude of Health Personnel↗
PubMed1988

Major blunt abdominal trauma due to child abuse.

We reviewed 15 years' experience with childhood trauma at two hospitals in different cities, one a city hospital, the other a children's hospital, to learn the extent, circumstances, presentations, and consequences of major blunt abdominal trauma due to child abuse. Some 10,000 children admitted to these hospitals for treatment of injuries from 1972 through 1986 provided the basis for the study; the incidence and severity of pediatric trauma at the two hospitals was similar, in that 13% of the visits to both hospitals' emergency rooms were for trauma, of which 5% resulted in admission. Major blunt abdominal trauma due to child abuse accounted for 22 of these cases, six at the former, 16 at the latter, and represented less than 0.50% of all abused children seen at both institutions. The average age was 24 mo; 14 were boys and eight were girls. In only two instances was the family unit intact; in both, the child was abused by the babysitter. Otherwise, the father, or the mother's "boyfriend," was responsible. Overall mortality was 45%, and was related both to type of injury and presenting signs. Of one who presented with an epigastric mass due to a pancreatic hematoma, none died; the pseudocyst which subsequently developed resolved on bowel rest and TPN. Of three who presented with bilious vomiting due to duodenal hematoma, none died; one required operative evacuation. Of five who presented with peritonitis due to duodenojejunal rupture, one died; this child presented greater than 24 hr following injury in profound septic shock. Of three who presented with hypovolemia due to moderate hemorrhage, none died; the former two were managed conservatively.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdominal Injuries↗
PubMed1988

Variations in pregnancy outcomes and use of obstetric procedures in two institutions with divergent philosophies of maternity care.

Pregnancy outcomes were compared between a stratified random sample of 796 women delivering a live birth at a maternity center (BMC) and a frequency matched sample of 804 women delivering a live birth at a tertiary hospital (TJUH) in 1977-1978. The relationship of use of obstetric procedures with pregnancy outcomes was investigated within and between the two samples. The neonatal morbidity rate, as measured by Hobel's neonatal risk score, was significantly higher and mean birth weights were lower at TJUH than at BMC when adjusted for institutional differences in use of obstetric procedures, medical-obstetric risk, and demographic characteristics. Conversely, the proportion of newborns with low 1-minute Apgar scores (fewer than seven) was significantly greater at BMC. The relationship of use of obstetric procedures with each outcome varied between the two institutions as well as across the three measures of pregnancy outcomes. The relationship of use of some procedures with each outcome may be explained in part by use of the procedure because of a suspected poor outcome of pregnancy, rather than an elevated risk of poor outcomes because of use of the procedure. Self-selection of some patients to BMC cannot be ruled out as a possible explanation for institutional differences.

Anesthesia, Obstetrical↗
PubMed1988

Continuing education for general practitioners.

This research was conducted to investigate patterns of attendance at continuing education meetings and examine which factors encourage or inhibit attendance by comparing the characteristics of general practitioners who attend regularly with those who attend occasionally or not at all. The findings provide course organizers with a detailed insight into the attitudes and perceptions of frequent and infrequent attenders. The research identifies a need for greater personal contact in changing attitudes to continuing education and bringing about greater involvement. It is concluded that the role of general practitioner tutor should be enhanced to provide more direct contact and influence with small groups of doctors.

Adult↗