Biomedical subjects

S D Hamburger

Publications and source records attributed to S D Hamburger.

67 records · Page 4Linked to original sources

PubMed1989

EEG spectra in severely dyslexic men: rest and word and design recognition.

To identify and localize differences in brain functioning, electrical activity was recorded with a full complement of scalp electrodes in 14 healthy, severely dyslexic men (mean age = 22 years, S.D. = 3) and 15 matched controls during rest and during word and design recognition. The electroencephalograms were spectrum analyzed, and the mean amplitude in each of 5 bands--delta, theta, alpha, slow beta and fast beta--compared topographically between conditions and groups. The two tasks did not elicit differentially lateralized patterns of electrical activity, but produced anteroposterior differences in alpha and theta. The Designs task, more difficult for both groups, was associated with less posterior alpha than was the Words task. The strongest group difference was likewise seen along an anteroposterior axis on the Designs task. With performance equal to that of controls, the dyslexics showed relatively greater fronto-central theta and less posterior theta (a more activated state), suggesting that dyslexics were compensating for less efficient information processing. There were no group differences in overall amplitude in any band for any condition. The differences in the topographic distribution of theta may reflect subtle differences in brain organization or compensatory recruitment of widely distributed neuronal networks.

Adult↗

PubMed1989

Urinary free cortisol output and disruptive behavior in children.

Hostile, impulsive, and aggressive behaviors have been associated with decreased urinary free cortisol (UFC) output. This is the first study to assess 24-hour UFC output in disruptive behavior disorders. The UFC of 19 boys with attention deficit and/or conduct disorder was compared with that of 19 age, race, and IQ matched normal controls studied as inpatients. Continuous Performance Test scores showed greater impulsivity in the disruptive group. UFC output did not differ between groups. However, UFC and difficulty were positively correlated on the continuous performance test in the form of longer interstimulus intervals and longer reaction times.

Adolescent↗

PubMed1989

Lack of seasonal variation in pediatric lumbar cerebrospinal fluid neurotransmitter metabolite concentrations.

Seasonal variation of cerebrospinal fluid (CSF) monoamines, particularly 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA) has been reported for psychiatrically ill and normal adults. Circannual variability was examined for a group of 72 children (mean age = 159.4 +/- 40.3 (SD), range 77-238 months), with a primary diagnosis of obsessive-compulsive disorder (OCD) or disruptive behavior disorder (DBD) (attention deficit disorder, oppositional disorder and/or conduct disorder), from whom CSF had been obtained systematically. There were no seasonal differences in mean concentrations of 3-methoxy-4-hydroxyphenylglycol (MHPG), HVA, or 5-HIAA, either for the group as a whole, for the separate diagnostic (OCD vs DBD) categories or for the pre-pubertal subgroup. Log-corrected HVA concentrations for the Tanner IV and V subgroup differed by season with summer concentrations less than those of fall (P = 0.06) and winter (P = 0.005). The results suggest that pubertal changes may play a role in any expression of circannual variability.

Adolescent↗

PubMed1989

Growth rate in adolescents with obsessive-compulsive disorder.

In an epidemiological study of 5,596 high school students, the authors identified 20 adolescents with obsessive-compulsive disorder and compared their physical size to that of adolescents of the same sex with no obsessive-compulsive symptoms. The obsessive-compulsive boys (N = 11) were shorter and weighed less than the other boys (N = 2,479) and were shorter than a subsample of normal boys (N = 33) and boys with other psychiatric diagnoses (N = 16). Regression analysis showed a flatter growth pattern through adolescence for the obsessive-compulsive boys (although within the 95% confidence limits for the other boys), suggesting a subtle neuroendocrine dysfunction in obsessive-compulsive disorder.

Adolescent↗

PubMed1988

The effect of methylphenidate on urinary catecholamine excretion in hyperactivity: a partial replication.

Children with attention deficit disorder with hyperactivity were treated with methylphenidate HCl (0.74 +/- 0.2 mg/kg/day) for 2 weeks in an open trial to assess changes in the urinary excretion of catecholamines and behavior. The purpose of this study was to confirm earlier work that methylphenidate has a distinctly different effect on urinary 3-methoxy-4-hydroxyphenylglycol (MHPG) excretion as compared to earlier studies with dextroamphetamine. Results confirmed the earlier finding that methylphenidate does not significantly change urinary MHPG excretion. No significant relationship was found between behavioral change and any of the urinary catecholamines or metabolites measured.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1988

Hemispheric asymmetries, fourth ventricular size, and cerebellar morphology in autism.

Hemispheric asymmetries, fourth ventricular size, and cerebellar morphology were examined in 15 healthy men, aged 18 to 39 years, with documented childhood diagnoses of infantile autism, and in 20 healthy age- and sex-matched controls using computerized transverse axial tomography (CT). Nine patients were of approximately average intelligence, 3 showed specific language impairments, and 3 were mentally retarded. No significant group differences were seen in the distributions of frontal or posterior asymmetries of width or petalia. No subject showed evidence of cerebellar atrophy or an enlarged fourth ventricle. These results fail to support a hypothesis of unusual hemispheric asymmetry or macroscopic abnormalities of the posterior fossa in autism.

Adolescent↗

PubMed1988

Concentration gradient of CSF monoamine metabolites in children and adolescents.

Whether the lumbar cerebrospinal fluid (CSF) concentration gradient of monoamine metabolites found in adults is influenced by age or pubertal status was studied in 26 children ranging from 6.5 to 17.3 years of age. Homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA), and 3-methoxy-4-hydroxyphenylglycol (MHPG) were assayed by high-power liquid chromatography (HPLC) with electrochemical detection. Eight patients were prepubertal (Tanner stage I). The slopes in units of picomoles/milliliter/milliliter for regression lines for CSF monoamine metabolite concentrations versus milliliter of CSF collected were 5.07 +/- 0.65, 10.13 +/- 2.0, and 0.67 +/- 0.22 for 5-HIAA, HVA, and MHPG, respectively, for the group as a whole. Significant correlations with age, height, weight, or Tanner stage were not found for the HVA or MHPG concentration gradients. Tanner stage and 5-HIAA slope were significantly correlated. Three of eight prepubertal patients had nonsignificant 5-HIAA gradients. CSF studies in pediatric populations must control for aliquot collected, as the size of the gradient could produce differences sufficient to mimic a "positive" clinical study if the aliquots collected are not the same.

Adolescent↗

PubMed1988

Objective and subjective side effects of research lumbar punctures in children and adolescents.

Lumbar punctures are a common clinical procedure in pediatric populations, yet little systematic information about side effects or the child's perspective of the procedure is available. In a subset (n = 20) of a sample of children and adolescents with disruptive behavior disorders, we recorded children's ratings of research lumbar puncture in comparison to other hospital experiences of blood sampling, electroencephalography, and going to school. Lumbar puncture did not differ from the other procedures in terms of preference. (School attendance was the last choice of 50% of our patients.) Postlumbar puncture headache occurred in 13 of 60 (22%) patients (age 6.5-19.8 years). Adults may overestimate the relative noxiousness of lumbar punctures in children.

Adolescent↗

PubMed1988

Neuropsychological findings in high-functioning men with infantile autism, residual state.

Ten men (ages 18-39) with clear histories of Infantile autism and approximately average verbal and nonverbal intelligence were studied with a comprehensive battery of neuropsychological tests. Comparisons with 10 matched normal controls showed no significant differences in many visuoperceptual or memory skills or in sensory-perceptual or motor skills or their lateralization. Differences seen on language measures were small, but statistically significant. In contrast to this, the autistic group demonstrated dramatic deficits on simple and complex, verbal and nonverbal problem-solving tasks, such as the Wisconsin Card Sorting Test, selected tasks from the Stanford-Binet, and the Trail Making Test. A left-hemisphere hypothesis of autism was not supported, nor was there compelling evidence of any posterior cortical deficit. Results are compatible with frontal-system dysfunction or with more widespread pathology.

Adolescent↗

PubMed1987

Regional cerebral blood flow in severe developmental dyslexia.

Regional cerebral blood flow was measured under three task conditions in 14 men with severe developmental dyslexia and their control subjects using a xenon 133 inhalation technique. No group differences in overall level or in pattern of gray matter flow were seen under relatively undemanding cognitive conditions. Despite minimal group differences in performance, the dyslexic group showed an increased hemispheric asymmetry (left greater than right) on a semantic classification task and a reduced anteroposterior difference on a line orientation task relative to controls. The exaggerated asymmetry suggests the possibility of less efficient information processing or inadequate bihemispheric integration. The reduced anteroposterior gradient may reflect a deficit in the ability of frontal systems to respond adequately to cognitive demands.

Adult↗

PubMedDate not supplied

Regional MRI measurements of the corpus callosum: a methodological and developmental study.

A technique for quantifying the midsagittal size and shape of the corpus callosum (CC) from magnetic resonance brain scans is presented. The technique utilizes the distances to the ventral and dorsal boundaries of small sectors of the CC from a reference point to compute the size and shape parameters of the CC and its subdivisions. Intrarater and interrater interclass correlation coefficients for the area measurements ranged from 0.88 to 0.99. Correlations between these automated measures and those obtained by pixel counting were equally high. The corpus callosa of 104 (57 male and 47 female) right-handed healthy children and adolescents, ages 4-18, were examined in relation to age and sex. Corpus callosum growth was most striking for the splenium and isthmus with some changes in the midbody regions. The area and perimeter of these regions increased, shapes became more compact, and the boundaries became more regular with age. The length and curvature at the anterior and posterior regions of the CC increased more rapidly in males than in females. These significant and consistent results indicate that the method is reliable and sensitive to developmental changes of the CC.

Adolescent↗

PubMedDate not supplied

Quantitative magnetic resonance imaging of human brain development: ages 4-18.

Brain magnetic resonance images (MRI) of 104 healthy children and adolescents, age 4-18, showed significant effects of age and gender on brain morphometry. Males had larger cerebral (9%) and cerebellar (8%) volumes (P < 0.0001 and P = 0.008, respectively), which remained significant even after correction for height and weight. After adjusting for cerebral size, the putamen and globus pallidus remained larger in males, while relative caudate size was larger in females. Neither cerebral nor cerebellar volume changed significantly across this age range. Lateral ventricular volume increased significantly in males (trend for females), with males showing an increase in slope after age 11. In males only, caudate and putamen decrease with age (P = 0.007 and 0.05, respectively). The left lateral ventricles and putamen were significantly greater than the right (P = 0.01 and 0.001, respectively). In contrast, the cerebral hemispheres and caudate showed a highly consistent right-greater-than-left asymmetry (P < 0.0001 for both). All volumes demonstrated a high degree of variability. These findings highlight gender-specific maturational changes of the developing brain and the need for large gender-matched samples in pediatric neuropsychiatric studies.

Adolescent↗

PubMedDate not supplied

Cerebral magnetic resonance image segmentation using data fusion.

OBJECTIVE: A semiautomated method is described for segmenting dual echo MR head scans into gray and white matter and CSF. The method is applied to brain scans of 80 healthy children and adolescents. MATERIALS AND METHODS: A probabilistic data fusion equation was used to combine simultaneously acquired T2-weighted and proton density head scans for tissue segmentation. The fusion equation optimizes the probability of a voxel being a particular tissue type, given the corresponding probabilities from both images. The algorithm accounts for the intensity inhomogeneities present in the images by fusion of local regions of the images. RESULTS: The method was validated using a phantom (agarose gel with iron oxide particles) and hand-segmented images. Gray and white matter volumes for subjects aged 20-30 years were close to those previously published. White matter and CSF volume increased and gray matter volume decreased significantly across ages 4-18 years. White matter, gray matter, and CSF volumes were larger for males than for females. Males and females showed similar change of gray and white matter volumes with age. CONCLUSION: This simple, reliable, and valid method can be employed in clinical research for quantification of gray and white matter and CSF volumes in MR head scans. Increase in white matter volume may reflect ongoing axonal growth and myelination, and gray matter reductions may reflect synaptic pruning or cell death in the age span of 4-18 years.

Adolescent↗