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Biomedical subjects

E K Anday

Publications and source records attributed to E K Anday.

At least 19 recordsLinked to original sources
PubMed1995

Ethanol, morphine and barbiturate alter the hemodynamic and cerebral response to cocaine in newborn pigs.

Newborns delivered to cocaine-abusing mothers are often exposed to other concurrently consumed illicit drugs, which may alter the hemodynamic and cerebral response to cocaine. This study examined the interaction of ethanol, morphine or barbiturate with cocaine on mean arterial pressure (MAP), cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) in newborn pigs. CBF, CMRO2 and cerebral O2 extraction (CEO2) were measured before and 4 and 10 min after cocaine (1.5 mg/kg i.v.) was administered in piglets that were awake, or pretreated with morphine, ethanol or pentobarbital. In awake piglets, cocaine increased CMRO2 and CEO2 while it had no significant effect on CBF. Conversely, in morphine- and ethanol-pretreated piglets, cocaine decreased CMRO2, decreased CBF and had not effect on CEO2. In awake piglets, cocaine increased MAP, whereas in morphine- or ethanol-pretreated piglets, cocaine decreased MAP. In the pentobarbital group, cocaine had no effect. These data demonstrate that other drugs of abuse alter the hemodynamic and cerebral effects of cocaine in the immature animal and may contribute to the central nervous system abnormalities in 'crack babies'.

Animals↗
PubMed1994

Alteration of brain cell membrane function following cocaine exposure in the fetal guinea pig.

The effect of cocaine on brain cell membrane structure and function was studied in the fetal guinea pig. We tested the hypothesis that cocaine, a potent vasoconstrictor, would result in brain cell membrane dysfunction as determined by altered activity of Na+,K(+)-ATPase and the appearance of products of membrane lipid peroxidation (conjugated dienes (CD) and fluorescent compounds (FC)). A total of 14 pregnant guinea pigs were studied at term (60 days). One hour prior to delivery, the pregnant guinea pigs were divided into 3 groups as follows: cocaine, 30 mg/kg i.p., saline placebo i.p., or 7% FiO2 for 1 h. Following cocaine, brain Na+,K(+)-ATPase activity decreased (mean +/- S.D., 25.6 +/- 9.2 vs. 54.6 +/- 3.4 mumol Pi/mg protein/h, cocaine vs. control, respectively, P < 0.01) and was similar to the hypoxia group (21.9 +/- 2.8 mumol Pi/mg protein/h). The products of lipid peroxidation did not change significantly following cocaine whereas hypoxia resulted in a rise in CD from 0 to 0.175 +/- 0.015 mumol/g brain, control vs. hypoxia, (P < 0.01), and FC from 1.13 +/- 0.15 to 1.88 +/- 0.13 micrograms quinine sulfate/g brain, control vs. hypoxia, (P < 0.01). These data show that acute fetal cocaine exposure, unlike hypoxia alone, results in a significant decrease in Na+,(K+)-ATPase activity without a significant increase in the products of lipid peroxidation, suggesting the mechanism by which cocaine affects brain cell membrane integrity is distinct from hypoxia. Inhibition of the enzyme activity may be due to a direct action of cocaine on the enzyme or due to enzyme regulation by cocaine-induced alterations in neurotransmitters.

Animals↗
PubMed1993

Response of the newborn cerebral circulation to cocaine.

Cocaine abuse by pregnant women is often associated with neurological injury in the newborn. To explore a vascular-related mechanism of injury, we investigated the effect of cocaine on the cerebral circulation in newborn pigs. During normoxic conditions, cocaine administration (1.5 mg/kg i.v.), resulting in peak plasma cocaine levels on the order of 10(-6) M, decreased cerebral blood flow (CBF) by 14%, as measured by the tracer microsphere method. To elicit the mechanisms by which cocaine decreased CBF, closed cranial windows were placed and the diameter of pial arterioles was measured by intravital microscopy while cocaine (10(-6) M) was applied onto the cortical surface. Topically applied cocaine decreased pial arteriolar diameter by 9%. Vasoconstriction induced by topically applied cocaine was blocked by tetrodotoxin (10(-7) M, Na+ channel blocker), whereas phentolamine (10(-5) M, noradrenergic receptor blocker) had no effect on the arteriolar response to cocaine, which suggested that cocaine effected constriction by an anesthetic and not a sympathomimetic mechanism. To evaluate this hypothesis further, cerebral vessels in the right hemibrain were sympathetically denervated while those in the left hemibrain remained innervated. During normoxia, cocaine (1.5 mg/kg i.v.) decreased CBF equally in both hemibrains, confirming the non-sympathomimetic mechanism. During asphyxia, cocaine administration attenuated cerebral hyperemia in both hemibrains, but in innervated more than in denervated, indicating that anesthetic and sympathomimetic vasoconstriction occurred during asphyxia. We conclude that cocaine constricts the immature cerebrovasculature and decreases CBF by an anesthetic mechanism during normoxic conditions and by both sympathomimetic and anesthetic mechanisms during asphyxia.

Animals↗
PubMed1993

Pharmacokinetics and effect of cocaine on cerebral blood flow in the newborn.

The present study investigated the effect of cocaine (COC) on cerebral circulation (CBF) and oxidative metabolism (CMRO2) in the newborn piglet and aimed to relate pharmacokinetics of cocaine to cerebrovascular effects. COC decreased CBF and CMRO2 from 75 to 64 and 4.27 to 3.91 ml/min/100 g, respectively, at 4 min with reduced flow to all brain regions (p < 0.05) which returned to baseline by 10 min. COC was rapidly metabolized with a t1/2 of 43 min and peak plasma concentration of 1,172 ng/ml. Norcocaine (NOR) appeared in plasma and CSF within 3 min of cocaine administration and remained elevated for the duration of the study along with COC in the CSF. These data show that the timing of the peak plasma COC level is associated with maximal decreased CBF. Further, the stable elevated level of COC and NOR in the CSF suggests that biotransformation does not occur in the brain. As a result, accumulation of these drugs may occur in the brain with successive COC use and affect the developing CNS in a deleterious manner.

Animals↗
PubMed1991

Pneumograms in premature infants: a study of longitudinal data.

In order to define longitudinal data in premature infants, impedance pneumograms were performed weekly on 23 healthy premature infants. Studies were performed while infants remained hospitalized and at the discretion of the attending physician following discharge. A total of 97 studies were obtained on the study group. The recordings were analyzed for percentage of sleep time spent in periodic breathing, apnea density, and duration of longest apneic pause. Infants in this study demonstrated decreased percent of periodic breathing and decreased apnea density with increased maturation; longest pause per recording was independent of postconceptional age. Results from this study provide data to assist in the evaluation of pneumograms in the premature infant.

Gestational Age↗
PubMed1991

Comparison of reflex modification procedures and auditory brainstem response in high-risk neonates.

This study compared the results of reflex modification (RM)--an objective technique for assessing brainstem sensorineural processing--with those of auditory brainstem response (ABR) for a group of high-risk infants at comparable postconceptional ages. For the RM procedure, an eyeblink-eliciting tap to the glabella was presented either alone or accompanied by a brief 90dB SPL tone. 37 high-risk infants were tested with both RM and ABR at a mean postconceptional age of 37.3 weeks. Seven had an increased brainstem conduction time ('failed ABR') and eight did not exhibit significant reflex augmentation ('failed RM'), seven of whom also failed the ABR. These data provide evidence that sensory stimuli which affect the neural mechanisms responsible for the organization of the startle response and auditory processing share essential neural components.

Auditory Pathways↗
PubMed1990

The blink reflex: maturation and modification in the neonate.

The onset and development of the delayed blink response, elicited by a tap to the glabella, and its modification by an acoustic stimulus (tone), were studied longitudinally in 36 healthy preterm and 43 term infants. Blink amplitude increased with gestational age. By term postconceptional age, the responses of the preterm infants to tap alone, and to both tap and tone, were not significantly different from those of the term infants. These results suggest that neurological development, as reflected by the blink reflex and its modification, proceeds in an orderly, sequential fashion and that the mechanisms affecting these brainstem processes are not altered by environmental influences.

Blinking↗
PubMed1989

Sensory processing in the term and preterm infant: use of reflex modification procedures.

The present study uses the glabellar reflex and reflex modification procedures to assess acoustic and tactile sensory processing capabilities in the human neonate. Fourteen term infants and 28 clinically stable preterm infants were given identical test paradigms. Augmentation testing consisted of a 16 V dc tap presented simultaneously with a 90 dB SPL tone; inhibition testing consisted of a 16 V tap preceded 900 msec. by an identical tap. All 14 term infants showed augmentation with 8 of 14 at p less than 0.05 level and eleven of 14 showed significant inhibition at the 900 msec intertap interval. However, only 12 of 28 preterm infants demonstrated significant augmentation and none showed reliable inhibition. These data indicate that areas of the central nervous system that process sensory stimuli are not fully developed at the time of birth even in the term infant. Further, the neural system for augmentation and inhibition may be independent of each other.

Acoustic Stimulation↗
PubMed1989

Altered brainstem sensory processing as assessed by reflex modification procedures in infants at risk for apnea.

Reflex modification procedures were used to test sensory processing in premature infants to examine the relationship between respiratory abnormalities and brainstem neuronal function. A total of 73 premature infants at risk for apnea and/or infants receiving methylxanthine therapy was given a 12-h pneumocardiogram and reflex modification test at a comparable postconceptional age, before discharge. Reflex modification was tested using a controlled eyeblink-eliciting tap to the glabella presented either alone or with a 1 kHz 90-dB SPL tone. The amplitude of the glabellar tap eyeblink and acoustically modified blink were lower in infants discharged on cardiac/apnea monitors (n = 36) than in the unmonitored group (1.44 and 1.59 volts versus 2.15 and 2.39 V, p less than 0.005, respectively). At follow-up, 12 monitored infants had clinically significant apnea after discharge. The records of this subgroup of infants revealed a significantly lower augmentation of the glabellar eyeblink response when compared to all infants screened for respiratory abnormalities and to the other monitored babies (p less than 0.01). The data suggest that abnormalities of the ventilatory pattern and occurrence of clinical apnea in preterm infants may in some measure be related to acoustic sensory processing, implying an alteration of brainstem neuronal function and organization.

Acoustic Stimulation↗
PubMed1989

Effect of in utero cocaine exposure on startle and its modification.

The effect of prenatal cocaine on acoustic sensorineural reactivity was assessed using reflex modification procedures in infants born to mothers with cocaine abuse (C-exposed). Reflex modification was tested using a controlled eyeblink-eliciting tap to the glabella presented either alone or with a 90-dB SPL tone. The results from 19 C-exposed infants were compared to 19 healthy matched drug-free infants. ANOVA comparison of the two groups showed C-exposed infants were more reactive in general, as indicated by a larger glabellar reflex, and more responsive to auditory stimuli, as indicated by an increased blink when the tone accompanied the tap (p less than 0.05). These data suggest that in utero cocaine exposure may have a direct effect on sensorineural processing and may place these infants at risk for cognitive and/or neurological sequelae.

Blinking↗
PubMed1988

Reflex modification audiometry: assessment of acoustic sensory processing in the term neonate.

Behavioral and physiological work in animals and adult humans have established the sensitivity of various procedures and allowed delineation of the neuroanatomical pathways involved in sensory processing. Herein we used the glabellar reflex and reflex modification procedures to assess acoustic sensory processing capabilities in the term newborn infant. The eyeblink-eliciting device consisted of a miniature solenoid which could deliver a controlled tap. A photoreflective densitometer attached to a TDH-39 earphone assessed the eyeblinks. A total of 98 term infants was studied to determine how a response to a reflex-eliciting event (tap) was modified (either augmented or inhibited) by a mild exteroceptive stimulus (tone) which was presented at an appropriate lead interval. Ninety adult subjects were given identical testing procedures and their data were compared to that of the infants. The results of this study showed that newborn infants reliably exhibited an eyeblink response after a tap to the glabella. With fixed intensity tones, frequencies from 1 to 4 kHz produced equivalent amounts of reflex augmentation in infants and adult subjects. Blink amplitude increased as a function of increased tap and tone intensity in both infants and adults. State change was shown to affect the amplitude of the reflexive eyeblink, but not the augmentation effect. However, neonates failed to show inhibition to either acoustic lactile stimuli at an interstimulus interval that produced significant inhibition in the adult. These data indicate that reflex modification procedures provide an objective assessment of acoustic sensory processing in the term neonate.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗
PubMed1987

Inhibition of the eyeblink reflex in the human infant.

In human adults the eyeblink elicited by a given stimulus can be inhibited if that stimulus is preceded by another stimulus at an appropriate lead interval. In the present work, pairs of eyeblink-eliciting stimuli separated by 300-1200 msec were presented to sleeping preterm and full-term infants as well as to adults. Preterm infants did not exhibit reliable inhibition at any interval. Full-term infants did so, but they required longer interstimulus intervals than were needed for inhibition in the adult subjects. Results imply that the neural systems that mediate reflex inhibition are functional at birth, but that they are relatively slow to act.

Adolescent↗
PubMed1986

Reflex augmentation of a tap-elicited eyeblink: the effects of tone frequency and tap intensity.

The amplitude of the human eyeblink elicited by a mild tap between the eyebrows can be increased if a brief tone is presented simultaneously with the tap. In two experiments we examined how this reflex augmentation effect varies with changes in the frequency characteristics of the tone and with changes in the intensity of the tap. We also examined how these effects change in the course of development. For newborn infants and for adults, fixed intensity tones with frequencies of either 1, 2, or 4 kHz produced equivalent amounts of reflex augmentation. Furthermore, while blink amplitude was an increasing function of tap intensity in both populations, the amount of reflex augmentation engendered by a simultaneously presented tone was independent of the intensity of the tap.

Acoustic Stimulation↗
PubMed1985

Respiratory complications of metatropic dwarfism.

Two infants with clinical and radiologic features of metatropic dwarfism presented in the neonatal period with episodes of cyanosis. Diagnostic studies to determine the etiology of these spells, including electrocardiogram, electroencephalogram, arterial blood gases, and metabolic and sepsis studies, were unremarkable. Chest roentgenograms revealed the characteristic long, narrow thoracic cage with no evidence of parenchymal disease. Cervical spine stability evaluation, pulmonary function studies, and chest impedance monitoring with qualitative air flow thermistor studies and transcutaneous oxygen monitoring were carried out. Both patients demonstrated a significant increase in resistance of the respiratory system following passive maneuvering of the head from a neutral position, suggestive of hypopharyngeal air flow obstruction. Obstructive sleep apnea resulting in cyanosis was documented in both patients. All other studies failed to yield a cause for the episodes of cyanosis. Our investigation failed to alter the clinical course which resulted in respiratory arrest and death by 7 months of age. A table is presented for the differentiation of skeletal dysplasias presenting in the perinatal period.

Cervical Vertebrae↗
PubMed1984

Edema, hypoproteinemia, and zinc deficiency in low-birth-weight infants.

Three premature infants with zinc deficiency who had an unusual presentation with generalized edema and hypoproteinemia between 5 and 9 weeks of age are described. The infants were fed their own mother's milk, supplemented with a proprietary formula after the first 2 to 3 weeks of life. None of the infants had diarrhea, liver disease, or urinary protein loss. Treatment with oral zinc supplements led to rapid resolution of the edema, with an increase in values for serum proteins, alkaline phosphatase, and zinc. There was no recurrence of symptoms following discontinuation of zinc therapy 1 month later. At 1-year follow-up, all infants were doing well and had normal growth and development. As zinc plays a critical role in nucleic acid and protein synthesis, it is postulated that dietary zinc deficiency in the phase of rapid postnatal growth precipitated edema and hypoproteinemia in these infants. Zinc deficiency should be included in the list of causes of generalized edema in the low-birth-weight infant.

Diagnosis, Differential↗
PubMed1983

The effect of early feeding on plasma glucose levels in SGA infants.

Plasma glucose levels were measured during the first day of life in 24 small-for-gestational-age (SGA) infants who began formula feedings within two hours of birth. In contrast to the high incidence of low blood sugar seen previously in fasted SGA infants, no infant had a plasma glucose below 30 mg/dl; after the first feeding, no values below 40 mg/dl occurred. Mean plasma glucose levels were lower in infants born to mothers with preeclampsia (57.2 +/- 2 vs 69.7 +/- 2.3 mg/dl, p less than .005). The results indicate that hypoglycemia (plasma glucose less than 40 mg/dl) can be easily avoided in SGA infants simply by providing adequate calories without delay after delivery.

Black People↗