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Biomedical subjects

C C Duncan

Publications and source records attributed to C C Duncan.

At least 37 records · Page 2Linked to original sources
PubMed1994

Developmental dyslexia and attention dysfunction in adults: brain potential indices of information processing.

Event-related brain potentials (ERPs) were recorded from a group of 13 men with severe developmental dyslexia and 15 matched normal controls. Auditory and visual stimuli, presented in separate reaction time tasks of graded difficulty, were used to elicit ERPs. No group differences in P300 were seen under relatively undemanding task conditions. However, as task demands increased, visual P300 was reduced in the dyslexic men as compared with the normal readers. An Abbreviated Conners Parent Rating Scale was used to assess retrospectively childhood symptoms of attention-deficit hyperactivity disorder (ADHD). Additional analyses revealed that the dyslexics with a history of many symptoms of ADHD in childhood (high ADHD) accounted for the group differences in P300; the dyslexics with a history of few or no such symptoms (low ADHD) were indistinguishable from the controls at all electrode sites. Furthermore, whereas the low-ADHD dyslexics showed the same hemispheric asymmetry in auditory P300 as did the controls (right > left), auditory P300 was more symmetrically distributed in the high-ADHD dyslexics. The results are interpreted as suggesting that a distinct brain organization may characterize dyslexic men with a history of concomitant deficits in attention.

Adult↗
PubMed1994

Low-dose indomethacin and prevention of intraventricular hemorrhage: a multicenter randomized trial.

OBJECTIVES: Parenchymal involvement of intraventricular hemorrhage (IVH) is a major risk factor for neurodevelopmental handicap in very low birth weight neonates. Previous trials have suggested that indomethacin would lower the incidence and severity of IVH in very low birth weight neonates. METHODS: We enrolled 431 neonates of 600- to 1250-g birth weight with no evidence for IVH at 6 to 11 hours of age in a prospective, randomized, placebo-controlled trial to test the hypothesis that low-dose indomethacin (0.1 mg/kg intravenously at 6 to 12 postnatal hours and every 24 hours for two more doses) would lower the incidence and severity of IVH. Serial cranial ultrasound examinations and echocardiographs were performed. RESULTS: There were no differences in the birth weight, gestational age, sex, Apgar scores, and percent of neonates treated with surfactant between the indomethacin and placebo groups. Within the first 5 days, 25 (12%) indomethacin-treated and 40 (18%) placebo-treated neonates developed IVH (P = .03, trend test). Only one indomethacin-treated patient experienced grade 4 IVH compared with 10 placebo-treated neonates (P = .01). Sixteen indomethacin-treated neonates and 29 control neonates died (P = .08); there was a difference favoring indomethacin with respect to survival time (P = .06). Eighty-six percent of all neonates had a patent ductus arteriosus on the first postnatal day; indomethacin was associated with significant ductal closure by the fifth day of life (P < .001). There were no differences in adverse events attributed to indomethacin between the two treatment groups. CONCLUSIONS: Low-dose prophylactic indomethacin significantly lowers the incidence and severity of IVH, particularly the severe form (grade 4 IVH). In addition, indomethacin closes the patent ductus arteriosus and is not associated with significant adverse drug events in very low birth weight neonates.

Cerebral Hemorrhage↗
PubMed1994

Using administrative data to screen hospitals for high complication rates.

Medicare's Peer Review Organizations (PROs) now are required to work with hospitals to improve patient outcomes. Which hospitals should be targeted? We used 1988 California discharge data to identify hospitals with higher-than-expected rates of complications in six adult, medical-surgical patient populations. Relative hospital complication rates generally were correlated across clinical areas, although correlations were lower between medical and surgical case types. Higher relative rates of complications were associated with larger size, major teaching facilities, and provision of open heart surgery, as well as with coding more diagnoses per case. Complication rates generally were not related significantly to hospital mortality rates as calculated by the Health Care Financing Administration. Different hospitals may be chosen for quality review depending on the method used to identify poor outcomes.

Aged↗
PubMed1993

Intraventricular hemorrhage and prematurity.

Intraventricular hemorrhage or hemorrhage into the germinal matrix tissues of the developing brain with possible rupture into the ventricular system and parenchyma remains a major problem of preterm neonates and is believed to be attributed to alterations in cerebral blood flow to a damaged germinal matrix capillary bed. Topics discussed in this article include germinal matrix anatomy and physiology, neuropathology, risk of hemorrhage, diagnostic imaging techniques, clinical manifestations, posthemorrhagic hydrocephalus, treatment, and outcomes.

Cerebral Hemorrhage↗
PubMed1992

Risk factors for early intraventricular hemorrhage in low birth weight infants.

Because earlier studies suggested that preterm infants with germinal matrix hemorrhage or intraventricular hemorrhage or both (GMH/IVH) present within the first 12 postnatal hours are at greatest risk for the development of high-grade hemorrhage and neurodevelopmental disability, we examined the risk factors for this insult among 229 neonates of 600 to 1250 gm birth weight in a multicenter study. All had echoencephalography (ECHO) within the first 11 hours and serially for the next 20 days; risk factor data were collected prospectively. Forty-three infants had GMH/IVH within the first 5 to 11 hours (mean age at ECHO 7.7 hours): 18 GMH and 21 grade II, 1 grade III, and 3 grade IV IVH. One hundred eighty-six infants did not have GMH/IVH at a mean age of 7.9 hours. Both groups of infants were similar in birth weight, gestational age, maternal risk factors, cord pH values, and surfactant therapy before ECHO. The group with early IVH had more vertex presentations than the group without early IVH (79% vs 55%, p = 0.043), less maternal tocolytic use (42% vs 60%, p = 0.029), and more vaginal deliveries (67% vs 44%, p = 0.005). In the first 21 days, severe IVH developed in 12 infants with early IVH and in 6 infants without early IVH (p < 0.001). There were more neonatal deaths (16% vs 6%, p = 0.035) and more deaths at any time during the primary hospitalization (23% vs 9%, p = 0.010) among the early IVH group than among the group without early IVH. Multivariate analysis indicated that the mode of delivery, fetal presentation, and birth weight were important and independent prognostic indicators of IVH.

Birth Weight↗
PubMed1992

A method for screening the quality of hospital care using administrative data: preliminary validation results.

Applying a computerized algorithm to administrative data to help assess the quality of hospital care is intriguing. As Iezzoni and colleagues point out, there are major differences of opinion as to the worth of such efforts. This article significantly advances the state of the art in using administrative data to screen for potential quality-of-care problems. In addition, this work on identifying complications of care goes well beyond the emphasis of many government organizations on hospital mortality rates. One question, however, not raised in the paper is: What is a practical upper limit to the sensitivity and specificity in comparing computerized screen results with the consensus judgments of a group of independent physicians? Advanced statistical techniques (such as bootstrapping) might be used to estimate the stability of consensus judgments by physician groups. When the judgments of two groups of physicians are compared with each other, the resulting sensitivity and specificity will not be .99! In addition, more training of members of the physician panels would probably have increased interrater reliability. While acknowledging this problem, the researchers' detailed analysis of the panel results is intriguing and represents a model for such studies. It is hoped that the authors will follow up on the avenues opened here. Furthermore, what degree of accuracy is necessary to identify facilities with higher-than-expected rates of complications? The authors discuss problems involved in using administrative data to target hospitals and departments for more costly in-depth reviews of quality. It is hoped that the promising findings that are reported here will be validated in other studies. Certainly their algorithms should find a ready audience in insurers and hospitals willing to try them out. Finally, should we expect additional research to lead to improvement in the authors' algorithms? I believe the algorithms will prove difficult to improve upon; but perhaps we should not worry about this. At some point, however, the cost of trying to identify and correct quality problems in "minimally outlier" hospitals will exceed the benefits, particularly given alternative uses for the funds. Might we now be close the the "flat of the curve" in the development of such systems for identification of quality problems? This issue should be discussed much further in future studies.

Abstracting and Indexing↗
PubMed1991

Analysis of the elements of attention: a neuropsychological approach.

A model for conceptualizing the components or elements of attention is presented. The model substitutes for the diffuse and global concept of "attention" a group of four processes and links them to a putative system of cerebral structures. Data in support of the model are presented; they are derived from neuropsychological test scores obtained from two samples, the first consisting of 203 adult neuropsychiatric patients and normal control subjects, and the second, an epidemiologically-based sample of 435 elementary school children. Principal components analyses of test scores from these two populations yielded similar results: a set of independent elements of attention that are assayed by different tests. This work presents a heuristic for clinical research in which the measurement of attention is essential.

Adult↗
PubMed1991

Cognition in eating disorders.

Cognitive functions were investigated in four groups of women: 30 underweight anorexics, 38 normal-weight bulimics, 20 long-term weight-restored anorexics, and 39 normal controls. A MANOVA was used to examine performance on five neuropsychological domains derived from prior principal components analyses of a comprehensive neuropsychological battery. Underweight anorexics performed more poorly than normal controls in four of five neuropsychological domains (focusing/execution, verbal, memory, and visuospatial), while normal-weight bulimics showed poorer performances only in focusing/execution. The absolute differences in scores between eating disorder groups and normal controls were for the most part small, suggesting subtle rather than frank cognitive difficulties. Poorer neuropsychological test performance was associated with anxiety but not depression as measured by the Tryon, Stein, and Chu Tension scale and scale 2 of the MMPI respectively. The findings support previous reports of attentional difficulties in eating disorders but do not support the hypothesis of differential right-hemisphere dysfunction in eating disorders.

Adult↗
PubMed1990

Effects of bright light on resting metabolic rate in patients with seasonal affective disorder and control subjects.

Many of the symptoms of seasonal affective disorder (SAD) could be construed as having an energy-conserving function. We predicted that SAD patients would have abnormally low resting metabolic rates (RMR), which would be increased to normal levels by light therapy. To test this hypothesis we measured RMR in 10 patients on and off light treatment and 9 normal controls. Contrary to our prediction we found that SAD patients had significantly higher RMR values compared with the normal population (p less than 0.02) and these values were significantly lowered by light treatment (p less than 0.05). The possible implications of these findings are discussed.

Adult↗
PubMed1989

Thromboxane synthesis inhibitor in a beagle pup model of perinatal asphyxia.

During perinatal asphyxia, cerebral blood flow is markedly reduced in the gray and white matter of the telencephalon. Since previous work has implicated prostaglandins in the control of blood flow, we tested the hypothesis that a thromboxane synthesis inhibitor would improve cerebral blood flow and blunt the metabolic alterations that accompany asphyxia. Forty-three newborn beagles 2-7 days old were anesthetized, ventilated, and randomized to insult (5 minutes of asphyxia) or no insult and received treatment with either the thromboxane synthesis inhibitor CGS 13080 (CIBA-GEIGY Corp.) (0.06 mg/kg/hr i.v. infusion) or saline. Cerebral blood flow was measured in 25 pups. Pups received treatment 30 minutes before insult or no insult. In pups randomized to insult and receiving saline, cerebral blood flow increased during insult in the medulla but decreased elsewhere. Pups randomized to insult and treated with thromboxane synthesis inhibitor had increased cerebral blood flow during insult in all cerebral regions studied. In addition, these pups experienced a significantly higher incidence of intraventricular hemorrhage than did pups randomized to insult and receiving saline. In other experiments with 18 pups, brain extracts were prepared for proton nuclear magnetic resonance spectral analysis of high-energy phosphorylated compounds and lactate levels. In pups exposed to insult and receiving saline, mean +/- SD phosphocreatine concentration fell from 1.9 +/- 0.1 to 0.4 +/- 0.1 mmol/kg, lactate concentration increased from 2.0 +/- 0.5 to 3.3 +/- 0.4 mmol/kg, and the calculated pH fell 0.8 units. There were no differences between groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1988

Randomized low-dose indomethacin trial for prevention of intraventricular hemorrhage in very low birth weight neonates.

We admitted 36 preterm neonates (600 to 1250 gm birth weight) with normal 6-hour echoencephalograms to a randomized, placebo-controlled prospective trial to determine whether a low dose of indomethacin would prevent germinal matrix or intraventricular hemorrhage and permit adequate urinary output. Between the sixth and tenth postnatal hours, indomethacin (0.1 mg/kg) or placebo was administered intravenously every 24 hours for a total of three doses. Cardiac ultrasound studies to assess the status of the ductus arteriosus were performed at 6 postnatal hours and on day 5. Urinary output, serum electrolytes, serum indomethacin levels, and renal and clotting functions were monitored. No differences in birth weight, gestational age, or Apgar scores were noted between the two groups of infants. Two indomethacin-treated infants and three infants given placebo had significant urinary output difficulties, requiring that the study medication be withheld. Of 19 infants given indomethacin, two had germinal matrix or intraventricular hemorrhage, in comparison with 8 of 17 infants given saline solution (p = 0.02). Of the infants who had a left-to-right patent ductus arteriosus shunt before treatment, 64% of the indomethacin-treated and 33% of the saline solution-treated infants no longer had a patent ductus arteriosus on day 5. Ductal status appeared unrelated to the development of germinal matrix or intraventricular hemorrhage.

Cerebral Hemorrhage↗
PubMed1988

Event-related brain potentials: a window on information processing in schizophrenia.

The application of the P300 component of the event-related brain potential to the study of attentional impairment in schizophrenia is discussed, and two recent studies are described. In one, the relative effects on P300 of stimulus modality and probability were evaluated. The data showed that the P300 is smaller in schizophrenic patients relative to normal controls for low-probability auditory stimuli. Next is described a preliminary report that evaluated whether this P300 reduction reflects a core deficit (trait marker) or clinical symptomatology (state marker). To pursue this question, a group of schizophrenic patients was studied on and off neuroleptic medication. The data showed that improvement in clinical state was highly correlated with increased visual P300 but was uncorrelated with auditory P300. These findings suggest that P300 elicited in the visual modality has the characteristics of a state marker of schizophrenia. In contrast, auditory P300 remains a candidate for a vulnerability trait marker of schizophrenia. The core deficit in schizophrenia thus appears to involve the auditory information-processing system, whereas fluctuations in clinical state may be reflected in the visual processing system.

Antipsychotic Agents↗
PubMed1988

Management of proximal shunt obstruction. Technical note.

Proximal shunt obstruction or obstruction of the ventricular catheter may present with signs and symptoms of shunt failure with either no cerebrospinal fluid flow or a falsely low intracranial pressure (ICP) upon shunt tap. The author reports a technique for lowering the ICP and for measuring the pressure in patients with such obstruction by cannulation of the reservoir and ventricular catheter to penetrate into the ventricle with a 3 1/2-in. No. 22 spinal needle. The findings in 20 cases in which this approach was utilized are summarized.

Cerebrospinal Fluid Shunts↗