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Biomedical subjects

D H Crowell

Publications and source records attributed to D H Crowell.

At least 19 recordsLinked to original sources
PubMed1992

Race, ethnicity and birth-weight: Hawaii 1983 to 1986.

A study of racial/ethnic-specific mean infant birth-weights reported on 1968 to 1972 live birth-weight certificates for Oahu, Hawaii is reviewed here. The 1983 to 1986 data confirm those earlier results: (a) The Hawaiian group is significantly heavier in mean birth-weights than other cohorts during the preterm period (33 to 36 weeks gestational age); (b) statistically significant differences also were present in mean birth-weights for the term and post-term periods (37 to 45 weeks gestational age); and (c) the ranking of cohorts from heaviest to lightest in mean birth-weights is Caucasian, Hawaiian, Japanese and Filipino respectively. The data raises 2 questions: (1) Which birth-weight standards are most applicable for Asian and Pacific Islanders; and (2) what are the implications of the race/ethnic-specific mean birth-weight differences relative to mortality, morbidity and developmental outcome?

Birth Weight↗
PubMed1989

Childhood developmental changes in the auditory P300.

In this study we investigated developmental changes in the auditory P3 latency from childhood to adolescence. Event-related potentials evoked by improbable auditory stimuli were recorded from 35 normal children between the ages of 5 and 13 years. Regression analyses showed significant age trends in the auditory P3 latency. Latencies decreased at a rapid rate (Cz: 20.34 msec/yr; Pz: 19.27 msec/yr) from childhood to adolescence, suggesting an increased efficiency in processing information as children mature. This rate was linear or constant in nature as evidenced by the failure of the quadratic and cubic components to significantly increase predictability of the regression equation. The slope of the P3 latency/age regression line was also shown to be influenced by the interactive effects of task difficulty and maturation. It was hypothesized that neuro-developmental processes (increased myelination and dendritic arborization) may underlie the maturational changes observed in the P3 latency during childhood.

Adolescent↗
PubMed1988

Identifying sleep apnea from self-reports.

An apnea score (AS) was developed as a potential screening tool for sleep apnea. This was based on self-report questionnaire responses of 76 sleep disorder center patients and 20 sleep survey volunteers. Twenty volunteers and 23 patients (group I) comprised the initial AS development group. Their questionnaire responses were compared to polysomnographic apnea indexes (AI) and apnea plus hypopnea indexes (AHI). Stepwise multivariate discriminant analysis was used to test whether or not selected group I questionnaire responses could be used to correctly classify respondents into apnea (AI or AHI greater than 5) or nonapnea (AI, AHI less than or equal to 5) groups. Self-reports of "stops breathing during sleep," "loud snoring," and history of adenoidectomy best discriminated normal (AI less than or equal to 5) from apnea (AI greater than 5) cases. The AS derived from group I responses to these three variables was then computed for group II (n = 53). After examination of the AS results, the AS was modified to include just "stops breathing" and "loud snoring" and the AI criterion was raised to 10 per hour. This revised AS correctly identified 100% of the cases with moderate-severe sleep apnea (AI or AHI greater than 40) and 70-76% of all sleep apnea cases with AI or AHI greater than 5. Predictive accuracy was 88% for AI greater than 10. The two questions that comprise the AS should be incorporated into risk appraisal instruments or interviews to screen for sleep apnea.

Adenoidectomy↗
PubMed1987

Auditory responsivity and intrauterine growth retardation in small for gestational age human newborns.

Auditory responsivity in term small for gestational age (SGA) compared to term appropriate for gestational age (AGA) human newborns reflects functional differences which may be attributable to intrauterine growth retardation (IUGR). Between-group comparisons of percent of responses of averaged late component auditory evoked events (AEEs) to pure tone stimuli (500, 1000, 2000, 4000, 6000 and 8000 Hz) at 63 and 80 dB SPL revealed significantly greater AGA responsivity at 80 dB SPL. Conversely, the AEE mean latencies were significantly shorter for SGA infants at both intensity levels. Between-group responsivity differences suggest developmental retardation in term (38-42 weeks) SGA newborns, but the faster SGA latencies may reflect 'induced' acceleration in auditory neurophysiologic function.

Auditory Perception↗
PubMed1982

Daytime sleep stage organization in three-month-old infants.

Sleep monitoring at 3 months post term of clinically normal term infants, pre-term infants with no demonstrable pathologic clinical signs, and pre-term and term infants with a history of metabolic disorders show that these infants have EEG sleep stages resembling those seen in adults, as well as the adult pattern of sleep stage organization. The presence of NREM stage organization and stage sequencing suggest that sleep regulatory mechanisms are approaching a level of functional maturity in the human infant at 3 months post term. There is a significant relationship between sleep staging at 3 months post term and mental and motor performance at 12 months post term. In light of this, it is hypothesized that early bioelectric maturation may reflect the development of neural mechanisms which are also the substrate for later cognitive and behavioral functioning. Sleep stage organization at 3 months post term may be utilized as a benchmark of CNS development and for research on the pathophysiology of sleep disorders.

Brain↗
PubMed1981

Multiple carboxylase deficiency: clinical and biochemical improvement following neonatal biotin treatment.

Multiple carboxylase deficiency is characterized by deficient activities of three biotin-dependent enzymes, propionyl coenzyme A carboxylase, pyruvate carboxylase, and beta-methylcrotonyl coenzyme A carboxylase. A newborn infant was seen with metabolic ketoacidosis, hyperammonemia, organic aciduria, seizures, and coma. Multiple carboxylase deficiency was subsequently confirmed by enzyme activity determinations in his peripheral blood leukocytes and cultured skin fibroblasts. The infant's neurologic and metabolic status improved markedly within a few days of administration of pharmacologic doses of oral biotin. His EEG, which was distinctly abnormal, became normal; his extensive computed tomography scan changes resolved, with the exception of ventricular dilation, over the next two months. After two weeks of biotin treatment the excretion of abnormal organic acid metabolites was reduced and his carboxylase activities increased to the normal range. However, the activities of these enzymes increased only to 30% to 55% of normal in fibroblasts incubated in supplemental biotin. This partial correction of enzyme activity differs from that observed in other individuals with multiple carboxylase deficiency and suggests biochemical heterogeneity in this disorder. Prompt diagnosis and intervention can avert some of the pathologic complications of this biotin-responsive condition.

Biotin↗
PubMed1980

Effects of induction of labor on the neurophysiologic functioning of newborn infants.

Neurophysiologic responses of newborn infants delivered after normal onset of labor are compared with those of newborn infants whose mothers had labor induced with oxytocin or prostaglandin F2 alpha. No differences in brain activity or heart rate were detected between groups in terms of frequency of response to auditory, visual, tactile, or olfactory stimulation. Significant differences were found for resting brain activity defined in terms of autoregressive spectral estimates or coefficients. The largest differences were between the groups with normal onset of labor and prostaglandin F2 alpha.

Autonomic Nervous System↗
PubMed1980

Autoregressive analysis: a method for detecting electroencephalic changes in newborns to tones.

This report presents an autoregressive technique for detectiong statistically significant changes in brain activity to tones. The change detectin model is applied to stationary time series electroencephalogram samples from sleeping newborn infants. The electroencephalic responses of neonates to tones are quantified and analyzed in terms of t-statistics. Confidence limits applied to averaged t-statistics objectively and reliably defined statistically significant late components in newborns.

Acoustic Stimulation↗
PubMed1979

A comparison of clinical behavioral audiometry and autoregression analysis of EEG and heart rate in hearing-impaired children.

Autoregressive analysis, a statistical technique for detecting changes in electroencephalic (EEG) and heart rate (HR) data was compared with clinical behavioral audiometric results on 10 hearing-impaired children in schools for the hard of hearing and deaf. EEG and HR data were collected in a screening paradigm involving tones of .5, 1, and 4 kc/s at 80 db SPL in a free field. An index of reliability, or acceptable level of agreement, was set at 70%. This criterion was met 5 out of 6 times. For the EEG, agreements exceeded 70% at 1 and at 4 kc/s, and for HR at all 3 frequencies. Results suggest that the autoregressive approach yields data very similar to behavioral audiometry in this population. Continued exploration of autoregressive analysis of electrophysiologic indices in determining reactivity to tones is warranted, particularly since the statistical method can be used with younger infants.

Audiometry↗