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G B Schaefer

Publications and source records attributed to G B Schaefer.

At least 55 records · Page 3Linked to original sources
PubMed1995

Neuroendocrine and neurophysiologic changes of adolescence.

This paper reviews the changes of adolescence that affect neuroendocrine and neurophysiologic functions. Normal variability in onset and progression of pubertal stages is discussed. The effects of hypothalamic and pituitary maturation and resulting changes in circulating hormone levels at the onset of secondary sexual characteristics are reviewed. Several theories and research data regarding the causes of the onset of puberty are identified. Abnormal symptoms of pubertal development are reviewed, and suggestions made for the Cleft Palate-Craniofacial team to monitor these symptoms.

Adolescent↗
PubMed1994

Linkage of a human brain malformation, familial holoprosencephaly, to chromosome 7 and evidence for genetic heterogeneity.

Holoprosencephaly (HPE) is a common malformation of the developing forebrain and midface characterized by incomplete penetrance and variable expressivity. Familial HPE has been reported in many families with autosomal dominant inheritance in some and apparent autosomal recessive inheritance in others. We have examined 125 individuals from nine families with autosomal dominant HPE. Expression in gene carriers varied from alobar HPE and cyclopia through microforms such as microcephaly or single central incisor to normal phenotype. We performed linkage studies by either Southern blot or polymerase chain reaction analyses with DNA markers (D7S22, D7S550, and D7S483) that are deleted from some patients with sporadic HPE and flank a translocation breakpoint in 7q36 associated with HPE. The strongest support for linkage was with D7S22, which was linked with no recombination to autosomal dominant HPE in eight of nine families with a combined logarithm of odds score of 6.4 with an affected-only model-free analysis and 8.2 with a reduced-penetrance model and all phenotypes. Close linkage to this region could be excluded in one family, and there was significant evidence of genetic heterogeneity. These results show that a gene for autosomal dominant HPE is located in a chromosomal region (7q36) known to be involved in sporadic HPE with visible cytogenetic deletions. They also demonstrate genetic heterogeneity in familial HPE. We hypothesize that mutations of a gene in 7q36, designated HPE3, are responsible for both sporadic HPE and a majority of families with autosomal dominant HPE.

Adolescent↗
PubMed1994

Hypoplasia of the cerebellar vermis and corpus callosum in thrombocytopenia with absent radius syndrome on MRI studies.

Thrombocytopenia with absent radius (TAR) syndrome is infrequently (7%) associated with mental retardation. In those cases, the mental deficiency is presumed to be a consequence of intracranial hemorrhage due to the thrombocytopenia. We report on 2 infants with TAR syndrome. One had developmental delay with evidence of cerebral dysgenesis by magnetic resonance imaging (MRI). Such findings have not been noted in the literature, but may not have been investigated in most cases. The other infant with TAR syndrome, who has had normal psychomotor development, has a normal brain on MRI scan. Detailed neuroimaging studies, preferably MRI, should be considered in the evaluation of patients with TAR syndrome, especially when there are documented signs of developmental delay, with or without a history of intracranial hemorrhage.

Abnormalities, Multiple↗
PubMed1994

Lipids and apolipoproteins in growth hormone-deficient children during treatment.

The role of growth hormone (GH) in regulating the transport of plasma lipoproteins has not been clearly defined, but past studies suggest that GH may influence cholesterol levels. This protocol was designed to evaluate possible changes in lipid and apolipoprotein status in GH-deficient children and children with neurosecretory dysfunction (NS) before GH therapy and at intervals after GH therapy was started. Twenty children with classic GH deficiency were evaluated, and 28% were hyperlipidemic at the onset of the study. Seven children were evaluated in the NS group, and only one (14%) showed an elevated total cholesterol (TC) greater than 200 mg/dL. The mean TC for all the GH-deficient children was elevated above the normal range, but not for the NS group. The mean apolipoprotein (apo) C-III level and its heparin-precipitated fraction (HP) were also elevated in the GH-deficient group, but only the apo C-III HP was elevated in the NS group. A standard replacement dose of recombinant methionyl GH was used, and therapy had no significant effect on TC or triglyceride (TG) levels. Apo C-III HP, a marker of hypertriglyceridemia, increased after the start of therapy, but no other lipoprotein levels changed significantly in the GH-deficient group. No changes were seen with treatment in the NS group. The longitudinal design of this study allowed demonstration of the later changes in the apolipoproteins and the presence of a distinct subset of patients with both GH deficiency and hypercholesterolemia. This study supports the role of GH in modulating lipid metabolism.

Adolescent↗
PubMed1994

Facial morphometry of Ecuadorian patients with growth hormone receptor deficiency/Laron syndrome.

Facial morphometry using computerised image analysis was performed on patients with growth hormone receptor deficiency (Laron syndrome) from an inbred population of southern Ecuador. Morphometrics were compared for 49 patients, 70 unaffected relatives, and 14 unrelated persons. Patients with growth hormone receptor deficiency showed significant decreases in measures of vertical facial growth as compared to unaffected relatives and unrelated persons with short stature from other causes. This report validates and quantifies the clinical impression of foreshortened facies in growth hormone receptor deficiency.

Adolescent↗
PubMed1994

Hypoplasia of the corpus callosum: a study of 445 consecutive MRI scans.

The size of the corpus callosum was assessed visually and by computer-assisted image analysis in a series of 445 consecutive magnetic resonance imaging (MRI) scans in children under 17 years of age. Fifty individuals were subjectively identified with small corpora callosa on visual inspection of the MRI scans. Seven patients had true hypoplasia of the corpus callosum after comparing the computer-measured relative size of the structure to previously established normal values. Five additional patients had complete agenesis, and two had partial agenesis of the corpus callosum. The cognitive functional levels of the seven patients with callosal hypoplasia and a control group of 63 randomly selected individuals from the remainder of the group were ascertained by record review. Seventy-one percent of the patients with hypoplasia of the corpus callosum and 29% of the control group had impaired function. The P value determined by Fisher's exact test was P = .061, suggesting that further study with greater numbers may be warranted. The prevalence of mental retardation in this condition, and the fact that hypoplasia is as common as complete and partial agenesis of the corpus callosum combined, suggest that hypoplasia of the corpus callosum is a marker of cerebral dysgenesis that should be looked for in the appropriate clinical setting.

Agenesis of Corpus Callosum↗
PubMed1994

Cerebral dysgenesis. An overview.

A significant portion of patients with neurodevelopmental abnormalities (mental retardation, learning disabilities, and so forth) have no definable cause for these problems. Mounting evidence suggests a substantial number of these idiopathic conditions have subtle abnormalities of brain development (cerebral dysgenesis) as the inherent pathophysiologic event. In this article the authors summarize normal and abnormal brain development, the diagnostic approach to idiopathic neurodevelopmental anomalies, and the new molecular genetic insights into the underlying causes of brain malformations.

Brain↗
PubMed1993

Patient with double heterozygosity for achondroplasia and pseudoachondroplasia, with comments on these conditions and the relationship between pseudoachondroplasia and multiple epiphyseal dysplasia, Fairbank type.

We present a 7 1/2-year-old girl with achondroplasia and pseudoachondroplasia. Her mother has achondroplasia and her father has pseudoachondroplasia. Radiographic manifestations of these two conditions from infancy to age 6 years are outlined. The findings in this patient are compared with those of achondroplastic patients and pseudoachondroplastic patients of similar ages. Our review of radiographs of many pseudoachondroplastic patients and subsequently of those of patients with multiple epiphyseal dysplasia (MED), Fairbank type, reinforced our opinion that pseudoachondroplasia and multiple epiphyseal dysplasia, Fairbank type, are closely related conditions. MED, Fairbank type, may be the mildest form of pseudoachondroplasia. Recently published electron microscopic findings also suggest this.

Achondroplasia↗
PubMed1993

Brain magnetic resonance imaging findings in the Opitz G/BBB syndrome: extension of the spectrum of midline brain anomalies.

We report the brain magnetic resonance imaging findings in 4 patients with the Opitz BBB/G syndrome. The scans were assessed by subjective interpretation and computerized image analysis. Findings noted in 3 of the 4 patients include hypoplasia or agenesis of the corpus callosum (3 patients), cerebellar vermal hypoplasia (2 patients), cortical atrophy and ventriculomegaly (3 patients), macro cisterna magna (3 patients), and a wide cavum septum pellucidum (1 patient). One patient had a normal scan. The demonstration of a wide cavum septum pellucidum extends the spectrum of midline brain anomalies (ventral induction defects) reported in this condition. This study along with other recent reports suggests that midline brain anomalies may be frequent findings in Opitz syndrome.

Adult↗
PubMed1993

Midline cerebral dysgenesis, dysfunction of the hypothalamic-pituitary axis, and fetal alcohol effects.

OBJECTIVE: Neuropathologic evaluation was performed on an infant with fetal alcohol effects. DESIGN: Coronal brain sections and representative tissue blocks stained with hematoxylin-eosin, silver stain, and immunocytochemical stains for hypothalamic and pituitary hormones were evaluated for neuropathologic abnormalities. PATIENT: A 2.5-month-old American Indian girl who had been exposed to first-trimester maternal binge alcohol abuse died after persistent problems of growth failure, sodium imbalance, aberrant temperature regulation, respiratory distress, and seizures. RESULTS: Autopsy revealed severe microcephaly, hypertelorism, midfacial hypoplasia, a high-arched palate, shortened palpebral fissures, and a small brain. The frontal lobes were fused anteriorly; olfactory bulbs and tracts were absent; and optic nerves were hypoplastic. An enlarged and bulbous hypothalamus obscured the pituitary gland. The thalamus and caudate nuclei were fused across the midline. Posteriorly, the single ventricle split to form rudimentary lateral horns. The anterior corpus callosum, septum pellucidum, fimbria, and fornices could not be identified. The anterior commissure and supraoptic nuclei were microscopically present. Many Purkinje cells were horizontally positioned, with abnormal dendritic structure. The posterior pituitary lobe was absent, and the infundibulum was flanked by a hypoplastic adenohypophysis and a large subarachnoid heterotopia. Immunocytochemical studies identified only vasopressin and neurophysin in the hypothalamus and only growth hormone and prolactin in the pituitary gland. CONCLUSION: To our knowledge, an association between fetal alcohol effects and a complex cerebral anomaly with features of incomplete holoprosencephaly and septo-optic dysplasia has not previously been reported and suggests a possible common pathogenesis needing further study.

Brain↗
PubMed1993

Elastin and fibrillin mRNA and protein levels in the ontogeny of normal human aorta.

Elastin associated microfibrils (EAMF) are ubiquitous connective tissue structures that are believed to provide tensile strength and flexibility to numerous tissues. In this study the ontogeny of EAMF in normal human aorta was examined using immunohistochemical analysis of fibrillin, an EAMF component, and mRNA levels of fibrillin and elastin. Specimens of infra-renal aorta from ages 11 months to 44 years were obtained following organ procurement. Decreasing amounts, as judged by computer digitized image analysis, of immunoreactive fibrillin when compared to elastin auto-fluorescence were observed in aortic sections with increasing age. Elastase treatment would un-mask the anti-fibrillin reactive epitope reinforcing the suggestion that EAMF act as a "scaffold" for elastin deposition. Northern and dot blot hybridizations demonstrated a decrease in relative fibrillin message levels with increasing age. The abundance of fibrillin in relation to elastin may suggest a role for EAMF independent of their association with elastin.

Actin Cytoskeleton↗
PubMed1992

Effect of attachment factors (pili plus Opa) on Neisseria gonorrhoeae invasion of human fallopian tube tissue in vitro: quantitation by computerized image analysis.

Pili (P) and opacity-associated proteins (Opa) facilitate Neisseria gonorrhoeae attachment to human fallopian tube epithelium. Subsequent effects on invasion are unproven. Computerized image analysis was used to study the effects of attachment factors on invasion by comparing a P+Opa+ variant to a P-Opa- variant of strain R10 in the fallopian tube organ culture model. Gonococci in sections of infected fallopian tube tissue were identified with FITC-labelled monoclonal anti-gonococcal antibodies. Nomarski DIC microscopy was used to establish anatomic boundaries that excluded extracellular gonococci from invasion measurements. The area of intracellular fluorescence served as an index of gonococcal invasion. With conservative criteria to exclude extracellular gonococci, the per cent of the intracellular area occupied by fluorescent P+Opa+ gonococci was 18% compared to 4.7% for the P-Opa- variant (P < 0.001). Data suggest that P+Opa+ organisms invaded deeper than P-Opa- microbes over the same time period (P = 0.029). Intra-observer variation in invasion measurements was not significant (P > or = 0.85), and inter-observer correlation was high (correlation coefficient = 0.96). Computerized image analysis is a rapid, reliable means of quantifying gonococcal invasion of fallopian tube epithelium. We conclude that gonococcal attachment factors can facilitate events which enhance gonococcal invasion of fallopian tube epithelium.

Antigens, Bacterial↗
PubMed1992

Evaluation of the child with idiopathic mental retardation.

A review of the advances in diagnostic techniques for evaluation of children with idiopathic mental retardation is presented. The current status of the use of clinical genetics, cytogenetics, molecular genetics, and neuroimaging in evaluating children with mental retardation is emphasized. Special attention is given to the evaluation of children with mental retardation and "autism" or "cerebral palsy."

Abnormalities, Multiple↗