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Biomedical subjects

C Cox

Publications and source records attributed to C Cox.

At least 379 records · Page 21Linked to original sources
PubMed1990

The adrenocortical response to brain injury: correlation with the severity of neurologic dysfunction, effects of intoxication, and patient outcome.

To test the hypothesis that cortisol levels reflect the extent of neurologic dysfunction and predict patient outcome, neurologic function and cortisol levels were determined in 120 traumatically brain injured patients who never received glucocorticoid treatment. Their mean age was 29 years and 78% were men. The impact of intoxication was examined in 59 patients who had ethanol levels measured. Ethanol was detectable in 40 patients and greater than or equal to 100 mg/dl in 31. There were significant correlations between the extent of neurologic dysfunction, determined by the Glasgow Coma Score and plasma cortisol concentrations 1 and 4 days postaccident. Cortisol levels were universally elevated on admission and approached normal 7 days later. Multiple linear regression analysis revealed significant effects of circulating ethanol levels on the association between cortisol concentrations and progressively worsening neurologic function, i.e., ethanol reduced the magnitude of the cortisol elevations in a dose dependent manner, abolishing this relationship at levels above 100 mg/dl. Analysis of the relationships between circulating cortisol levels and patient outcome provided a second method for ascertaining the association between injury severity and the magnitude of adrenocortical activation. Admission and day 1 cortisol concentrations were 25 to 40% lower in patients having good recoveries or moderate disabilities than those who remained severely disabled, persistently vegetative or died; serum cortisol values of less than 20 micrograms/dl one day after the accident were more likely to be associated with a good outcome than a poor one (55 vs. 25%, p less than 0.001). The worsening prognosis of patients having higher cortisol values is further reflected in the duration of acute hospitalization of these individuals.(ABSTRACT TRUNCATED AT 250 WORDS)

Accidents, Traffic↗
PubMed1990

Selective deficits in cognition and memory in high-functioning parkinsonian patients.

To evaluate the profile and extent of cognitive deficits in Parkinson's disease, afflicted patients of exceptional professional distinction, who continue to function successfully in leadership positions, were compared neuropsychologically to neurologically normal individuals, matched for sex, age, education and professional standing. While patients showed relative preservation of verbal skills and higher executive function, they exhibited a significant reduction in episodic memory and visuospatial function. The observation of circumscribed impairment in this select group of Parkinsonian patients further implicates cognitive and memory deficits as consistent features of Parkinson's disease.

Adult↗
PubMed1990

Word-association responses and severity of dementia in Alzheimer disease.

To test the impairment of semantic memory in Alzheimer Disease, two groups of patients (one French and one American) were given a free-word-association task. Analysis showed a strong correlation between the scores of the Mini-Mental State Examination and an index of commonality of responses in both groups. As the severity of dementia increased, Alzheimer patients were less likely to give common responses. Our results are consistent with those of previous studies showing a relationship between dementia severity and impairment in semantic memory in Alzheimer Disease.

Aged↗
PubMed1990

Chronic myelomonocytic leukemia.

Thirty adult patients with CMML were evaluated to determine prognostic factors that might have an impact on conversion to acute leukemia and survival. Neither leukocyte count nor monocyte count correlated with survival. The median survival for all 30 cases was 41 months. Patients with less than 5% marrow blasts had a median survival of 60 months but those with 5-20% blasts had only a 9-month median survival.

Aged↗
PubMed1990

Predicting risk for bronchopulmonary dysplasia: selection criteria for clinical trials.

Early identification of neonates in whom bronchopulmonary dysplasia is most likely to develop permits appropriate enrollment into clinical trials testing early intervention therapies for the prevention or treatment of bronchopulmonary dysplasia. Analysis of 160 neonatal intensive care unit survivors to 28 days revealed that supplemental oxygen requirement at 28 days could be predicted by a logistic regression including (1) birth weight, gestational age, 5-minute Apgar score, and peak inspiratory pressure at 12 hours for 12-hour-old neonates and (2) birth weight, gestational age, peak inspiratory pressure at 12 hours, and mean airway pressure at 10 days for 10-day-old neonates. These two regression analyses were applied prospectively to three new data sets totaling 238 neonates to test their predictive ability. Neonates were classified into low-, moderate-, or high-risk groups on the basis of their predicted probability of requiring oxygen supplementation at 28 days; low = probability of less than 25%, moderate = probability of 25% to 75%, and high = probability greater than 75%. Although these populations were demographically distinct from the original group, the regression analyses performed well. The regression analysis for 12 hours of age classified 125 neonates at low risk of whom 9% required supplemental oxygen at 28 days, and the regression analysis for 10 days classified 141 neonates at low risk of whom 7% required supplemental oxygen. The 12-hour regression analysis classified 80 neonates at moderate risk of whom 33% required supplemental oxygen at 28 days and the 10-day regression analysis classified 49 neonates at moderate risk of whom 24% required supplemental oxygen.(ABSTRACT TRUNCATED AT 250 WORDS)

Apgar Score↗
PubMed1990

Repetitive pulsed-train "off" duration mitigates reductions in root growth rates of Pisum sativum L. induced by 60-Hz electric field.

An investigation was undertaken to define a 60-Hz electric field exposure system which would affect a eukaryotic cell system while mitigating a potential thermal rise. The biological effectiveness of pulsed 60-Hz electric fields on a cell system of defined sensitivity to continuous-wave 60-Hz electric fields was sought. Roots of garden pea (Pisum sativum L.) were exposed to pulsed trains of 60-Hz, 430 V/m electric fields. The "on" time was constant at 1 s and the "off" time varied. The repetitive on:off regimens used were 1:20, 1:50, 1:100, 1:130, 1:200, and 1:300. With continuous or 1:20 pulsed fields the growth response was equivalent (representing a 60% depression in root growth rate). The severity of the growth effect diminished as the off time increased; for the 1:100 regimen, the relative growth rate was depressed by about 30%; for the 1:300 regimen, the relative growth rate was equal to that of the controls.

Electromagnetic Fields↗
PubMed1989

Tissue distribution of Pb in adult vs. old rats: a pilot study.

The coupling between the degenerative processes of aging and toxicant exposure has received little experimental attention. This experiment compared the tissue lead (Pb) distribution of adult and old rats exposed to 50 ppm Pb acetate in drinking water for 11 months and fed a semipurified diet. Blood Pb and zinc protoporphyrin (ZPP) determinations were carried out after 6 months of exposure; after 11 months of exposure blood lead and tissue Pb levels were determined. Several age-related differences between adult and old rats were noted: old rats exposed to Pb exhibited lower brain weights than old controls, a difference not noted between adult-control and adult-Pb rats. Pb-induced elevations of ZPP were confined to old-Pb rats while adult-Pb rats showed no increase relative to adult-controls. Blood lead values of adult-Pb and old-Pb rats showed differential trends over the course of exposure: adult values declined, while those of old rats tended to increase further. Brain lead concentrations, and to a marginally significant extent, liver Pb levels, rose higher in old-Pb rats than in adult-Pb rats, while bone Pb levels were significantly less than those of adult-Pb rats. The current findings confirm the assertion that tissue Pb distribution patterns may be markedly altered when Pb exposure occurs during the later stages of the life cycle.

Aging↗
PubMed1989

Relation of plasma D-dimer concentrations to coronary artery reperfusion before and after thrombolytic treatment in patients with acute myocardial infarction.

This study was designed to investigate the possible role of pre- and posttreatment plasma D-dimer concentration as a reflection of coronary artery thrombolysis. Blood was collected from 206 patients with angiographically documented acute coronary occlusion presenting within 6 hours of symptom onset who were enrolled in a prospective study comparing intravenous APSAC (30 U) (IV-APSAC) with intracoronary streptokinase (160,000 U) (IC-SK). D-dimer concentrations in 104 patients after IV-APSAC therapy were higher than in 90 patients after IC-SK (mean +/- standard error, 1,009 +/- 60 vs 603 +/- 45, p less than 0.001), but there was no difference in patients with and without reperfusion (1,096 +/- 88 vs 875 +/- 67, p = 0.1 for IV-APSAC, and 587 +/- 48 vs 634 +/- 95, p = 0.6 for IC-SK). The median concentrations before treatment were similar in the IV-APSAC and IC-SK groups (93 and 90 ng/ml, respectively). These were higher than the value in 25 ambulatory control subjects (72 ng/ml) but lower than in 29 post-AMI (6 to 30 hours) patients and in preoperative orthopedic patients (140 ng/ml each). There was no difference in D-dimer concentrations in patients with grade 0 or grade 1 coronary artery occlusion (median 85 vs 90 ng/ml) or in patients with or without ultimate successful reperfusion (median 85 vs 93 ng/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Measurement variability in DNA flow cytometry of replicate samples.

A Bladder Cancer Flow Cytometry Network study has been carried out aimed at identification of the sources of inter- and intralaboratory variability. Replicate "cocktail" samples containing a mixture of peripheral blood lymphocytes and an aneuploid cell line and samples of peripheral blood lymphocytes serving as a DNA reference standard were distributed to five network laboratories. The samples were stained for DNA using propidium iodide, with each laboratory using its own staining protocol. Sets of these samples were analyzed by flow cytometry to obtain cellular DNA distributions. DNA index and hyperdiploid fraction were calculated for each histogram using an automated technique. Results were evaluated by analysis of variance to identify sources of variability. Three important sources of variation were found that affect flow cytometry in general and- the transportability of flow cytometry results to routine clinical use in particular. The significant variation among laboratories that is constant across time most probably represents stable differences in instrumentation, instrument set-up, and laboratory techniques. This variation can be compensated for, if it is known and stable, to develop transportable classification criteria. The second type of variation, termed the interaction component, represents differences among laboratories that are not constant across time. Sources of this variation include inconsistency in sample preparation, staining, and analysis. The elimination of this type of variation is required for meaningful comparison of data within and among laboratories and the creation of interlaboratory data-bases. The third type of variation represents pure measurement variability and affects the sensitivity of the technique.

Cell Line↗
PubMed1989

Dopamine and memory function in Parkinson's disease.

Response fluctuations in motor function, complicating long-term dopaminomimetic therapy of Parkinson's disease, may extend to the cognitive realm. To evaluate the effect of levodopa treatment both on attention as well as acquisition and retrieval of memory tasks, parkinsonian patients were examined neuropsychologically both while medicated with levodopa/carbidopa ("on") and when the medication's antiparkinsonian effect had worn off ("off"). Significant cognitive differences emerged only on the delayed recall of complex verbal materials, where patients when "on" performed better compared with their "off" state. Comparison of change scores across states (administration or withholding of levodopa/carbidopa between acquisition and retrieval, "off" to "on" or "on" to "off"), revealed no substantial differences as a function of dopaminomimetic therapy. These results support the view that slight changes in cognition are associated with dopaminomimetic therapy of Parkinson's disease, but that these changes may be task-specific.

Aged↗
PubMed1989

Rerandomization tests for analyzing correlated data from dental studies.

Dental research studies often produce relatively small data sets in which observations are serially or spatially correlated. Rerandomization tests are presented as alternatives to analysis of variance and multivariate analysis for assessing group differences using such data. Rerandomization tests are particularly useful when the investigator is unwilling to make strong assumptions about the nature of the serial correlation or the distribution of the data. Two examples are discussed that demonstrate these techniques.

Data Interpretation, Statistical↗
PubMed1989

A test of I2t as a dose parameter for fetal weight reduction from exposure to ultrasound.

It has been suggested that fetal weight reduction by ultrasound exposure is linearly related to the dose parameter I2t, where I is the intensity and t the exposure time. A direct test of the concept was conducted using CF-1 mice. No effect on fetal weight was found at values of the dose parameter large enough to produce measurable heating in the fetal and maternal tissues.

Animals↗
PubMed1989

Dose-response analysis of infants prenatally exposed to methyl mercury: an application of a single compartment model to single-strand hair analysis.

A new method of estimating fetal exposure is used in a dose-response analysis of data from the 1971 outbreak of methyl mercury poisoning in rural Iraq. An X-ray fluorescence instrument for the measurement of single strands of human hair was employed to obtain longitudinal profiles recapitulating fetal exposure. Logit and hockey-stick models as well as nonparametric smoothing are used to describe data on delayed development and central nervous system abnormality.

Bread↗
PubMed1989

Decreased cholestasis with enteral instead of intravenous protein in the very low-birth-weight infant.

Thirty to 50% of very low-birth-weight infants have parenteral nutrition-associated cholestasis. To test the hypothesis that the incidence of cholestasis would be decreased if parenteral amino acids were avoided and protein given enterally, infants with a gestational age of less than 30 weeks were randomized to two groups. One group received amino acid-free parenteral nutrition and whey protein enterally with added premature infant formula. The control group received standard parenteral nutrition with amino acids and enteral premature formula. At the end of 3 weeks of parenteral nutrition, infants who had a direct serum bilirubin level of greater than 3 mg/dl were considered to have significant cholestasis. Twenty-nine infants required parenteral nutrition for 3 weeks, 17 in the whey group and 12 in the control group. No instances of significant cholestasis were observed in the whey group (0/17), whereas seven of 12 infants (58%) in the amino acid control group had cholestasis (p less than 0.001).

Amino Acids↗
PubMed1989

Prognostic significance of myeloperoxidase positivity of blast cells in acute myeloblastic leukemia without maturation (FAB: M1): an ECOG study.

The relationship between cell features by light microscopy and therapeutic outcome of 72 patients with acute myeloblastic leukemia (FAB M1) were investigated. The patients were divided into two groups according to myeloperoxidase-(MPO) positive percentage of blast cells, namely a low (less than 50%) and high (greater than 50%) MPO group. No remarkable morphological difference of blast cells between these two groups was observed. The 38 patients with low MPO showed a significantly lower complete response rate (CR) (52.6%) than the 34 patients with high MPO (85.3%) (p = 0.003) that included 10 CAE-positive patients and 2 ANAE-positive CAE-negative patients. The low MPO group included 5 CAE-positive patients with granulocyte dysplasia and 7 additional patients with alpha naphthyl acetate esterase (ANAE) positivity who were chloroacetate esterase (CAE) negative. Low positivity of blast cells may be due to a defective enzyme expression in the former but also may be a reflection of 'monocytic' aberrant expression in the latter. The low MPO group in M1 with this heterogeneous population is less likely to achieve CR with chemotherapy, while the high MPO group with a higher CR rate suggests a more pure entity within the myeloblastic leukemias referred to as M1. After further refinement by eliminating 24 cases that were 'esterase positive' (ANAE and/or CAE), the results were still the same, suggesting that the more immature blast populations were in the low MPO group.

Adult↗
PubMed1989

Extracorporeal membrane oxygenation for neonatal respiratory failure. A report of 50 cases.

From February 1985 through June 1987, 50 newborn infants in whom maximal ventilator therapy failed (80% predicted mortality) were treated with extracorporeal membrane oxygenation (ECMO) according to the following inclusion criteria: arterial oxygen tension less than 50 torr (alveolar-arterial oxygen gradient greater than 630 torr) for 2 hours or arterial oxygen tension less than 60 torr (alveolar-arterial oxygen gradient greater than 620 torr) for 8 hours. Criteria for exclusion from ECMO therapy included birth weight less than 2000 gm, gestational age less than 35 weeks, presence of intracranial hemorrhage, presence of other major congenital anomalies including cyanotic heart disease, and high levels of ventilatory support for more than 7 days. Mean birth weight was 3.28 +/- 0.56 kg, mean gestational age was 39.6 +/- 1.7 weeks, and mean age at the start of ECMO was 48.6 +/- 36.9 hours. Meconium aspiration, usually associated with persistent pulmonary hypertension, was the most common cause of pulmonary failure (62%). Mean pre-ECMO arterial oxygen tension during maximal ventilatory and pharmacologic support was 34.5 +/- 14.5 torr. Mean ventilatory support immediately before the institution of ECMO was as follows: peak inspiratory pressure 46.8 +/- 9.9 cm H2O, positive end-expiratory pressure 4.6 +/- 1.6 cm H2O, and intermittent mandatory ventilation rate 101.0 +/- 22.7 breaths/min with all patients receiving an inspired oxygen fraction of 1.0. Lung management to prevent pulmonary atelectasis during ECMO consisted of moderate levels of positive end-expiratory pressure (mean 10.3 +/- 2.6 cm H2O, range 8 to 14 in 94% of patients. Other mean ventilator parameters during ECMO were as follows: peak inspiratory pressure 22.8 +/- 1.6 cm H2O, intermittent mandatory ventilation rate 11.8 +/- 2.9, and inspired oxygen fraction 0.21. The overall long-term patient survival rate was 90%. Mean values for arterial blood gases and ventilator settings immediately after the discontinuation of ECMO were as follows: oxygen tension 78.4 +/- 22.1 torr, pH 7.39 +/- 0.10, carbon dioxide tension 37.4 +/- 10.7 torr, peak inspiratory pressure 25.2 +/- 3.9 cm H2O, positive end-expiratory pressure 5.6 +/- 1.2 cm H2O, and intermittent mandatory ventilation rate 41.3 +/- 12.6 with an inspired oxygen fraction of 0.42 +/- 0.17. Despite slightly higher levels of ventilator support (peak inspiratory pressure 46.8 versus 45.0 cm H2O, not significant) mean pre-ECMO oxygen tension was significantly lower than that reported from the National ECMO Registry (34.5 versus 42.0 torr, p less than 0.01).(ABSTRACT TRUNCATED AT 400 WORDS)

Extracorporeal Membrane Oxygenation↗
PubMed1988

Diluted formula for beginning the feeding of premature infants.

To evaluate whether there is a preferable mode of advancing feedings in premature infants, 50 infants with birth weights of less than 1500 g were randomized into two groups. Twenty-eight infants were begun on a regimen of full-strength (FS) formula (84 J/30 mL [20 cal/oz]), and the volume of formula was advanced on a daily basis. Twenty-two infants received half-strength formula (equal parts, 84 J/30 mL [20 cal/oz] formula and water) and were advanced at twice the volume per feeding as the FS group. The groups were compared with respect to the amount of time needed to reach an enteral energy intake of 420 J (100 cal)/kg. The half-strength feeding group had fewer residuals and reached the indicated energy intake level earlier than infants in the FS group.

Energy Intake↗