Biomedical subjects
T Lyngbye
Publications and source records attributed to T Lyngbye.
Use of banding techniques for zygosity diagnosis in twins.
Detailed comparison of human variant chromosomes found by Q- and C-banding technique is performed in a pair of twins to show that these variants can be used for zygosity diagnosis.
A girl with karyotype 46,XX,del(7)(qter-p 15:).
A girl with partial deletion of the short arms of one chromosome 7 is described. Among many other symptoms she has craniosynostoses. Early closure of cranio-sutures has previously been described in 2 of 3 patients with partial deletion 7. Investigation of a number of genetic marker systems shows that the HL-A, MN, AcP, and GPT loci are not located in the deleted segment.
[Deletion of the short arm of chromosome 7].
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Neurological deficits in children: medical risk factors and lead exposure.
A study of possible undue neurobehavioral effects of low-level lead exposure was performed in Danish school children who entered first grade in 1982. Lead absorption was found to relate to impaired psychological test performance and difficulties at school. However, this relationship was confounded by medical risk factors for neurological deficit. Such factors were used as exclusionary criteria before psychological testing and were selected a prior on the basis of a critical evaluation of known etiologies of neurobehavioral dysfunction. Children characterized by a medical risk factor tended to show performance below average and, at the same time, low lead absorption. The medical risks were also associated with delayed motor activity in the first year of life, thus perhaps resulting in diminished lead intake. This confounding effect makes strict exclusion for proven medical risk factors crucial to avoid bias toward the null-hypothesis. In spite of strict exclusion, a residual confounding due to health-related variables still remained. Inconsistent findings in the field of neurobehavioral studies may be partly explained by different means of identification and statistical treatment of medical risk factors.
A neuropsychological study of children with elevated dentine lead level: assessment of the effect of lead in different socio-economic groups.
The study was carried out in the municipality of Aarhus, a city of 250,000 inhabitants. The study was designed as a cross-sectional cohort study of school children in first grade in 1982-83. A total of 2,412 children were contacted and asked to submit their shed teeth to the teacher, and 1,291 children delivered at least one usable tooth (response rate, 54 percent). The lead level in circumpulpal dentin showed an average of 10.7 micrograms/g. Eight percent of the children (N = 110) had a lead level above 18.7 micrograms/g and were selected as a "high" lead exposure group. This group was matched by sex and socio-economic status of the parents with control children with a dentin lead level below 5 micrograms/g. Following a detailed interview with the parents, children were excluded from the study if medical risk factors were present. A clinical psychologist, blind to the lead data, administered selected psychometric tests to 162 of the children selected. The high-lead children scored lower on the WISC when compared to low-lead children, especially on the Verbal IQ (p less than 0.001) and Full Scale IQ (p less than 0.01). No significant difference was seen between the high- and low-exposure groups on the Performance IQ and on several experimental tests. Impaired function associated with lead exposure was also found on the Bender Visual Motor Gestalt Test (p less than 0.001) and on a behavioral rating scale (p less than 0.01). These results remained statistically significant even after controlling for socio-economic status and other confounding variables.
Early lead exposure and neonatal jaundice: relation to neurobehavioral performance at 15 years of age.
A cohort of children who attended first grade in 1983 was identified in a Danish community with low-level lead pollution. Two groups with high and low postnatal lead exposure were generated on the basis of the dentin-lead concentration in shed deciduous incisors. At age 8 years, examination of 162 children matched according to gender and socioeconomic status had shown lead-related deficits in verbal intelligence and visuomotor coordination. Re-examination was now carried out in 141 children at age 15 years using the Wechsler Intelligence Scale for Children (WISC), Bender Visual Motor Gestalt, Trail Making, and Visual Gestalts. In general, no lead-related effects could be detected in the group. However, in children with a history of neonatal jaundice, increased lead exposure was associated with mild neurobehavioral deficits, as indicated by lower verbal IQ scores and decreased visuomotor coordination. This finding suggested that moderate neonatal hyperbilirubinemia may have precipitated an increased sensitivity to subsequent exposure to lead.