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Biomedical subjects

T Lyngbye

Publications and source records attributed to T Lyngbye.

11 recordsLinked to original sources
PubMed1991

Lessons from a Danish study on neuropsychological impairment related to lead exposure.

Serious problems emerge when evaluating evidence on lead neurotoxicity in children. The extent of these problems and ways to control them were explored in a study of 1291 children from the first class in the schools of Aarhus municipality, Denmark. The lead retention in circumpulpal dentin in shed deciduous teeth was used as an indicator of cumulated lead exposure; it correlated most strongly with traffic density at the residence of each family and at the day-care institutions. In a nested case-control group selected on the basis of dentin lead concentrations, 29 of 200 children had encountered obstetrical complications and other medical risks for neurobehavioral dysfunction; these children primarily belonged to the low-lead group. As lead-related neurobehavioral effects are nonspecific, inclusion of these children in the data analysis would therefore have distorted the results toward the null hypothesis. Children from the high-lead group who had experienced neonatal jaundice showed impaired performance when compared to other high-lead children; this finding may suggest a synergistic effect. The Bender gestalt test scored by the Göttingen system was the test that was most sensitive to lead exposure. The conclusion that neurobehavioral effects can be caused by the relatively low lead exposures in Denmark may not be surprising, as current exposures to this toxic metal greatly exceed the prepollution levels to which the human body originally adapted.

Absorption↗
PubMed1991

Lead concentration in deciduous teeth from Danish school children.

Deciduous teeth were collected from school children in the first grade in six Danish municipalities; 2,033 teeth were received from 1,848 children. The geometric mean for the largest group (from Arhus) was 8.4 micrograms/g. The lead concentrations were similar in two Copenhagen suburbs with a secondary lead and a lead battery factory (geometric means, 9.6 and 9.9 micrograms/g, respectively). Increased lead concentrations were seen in children of low social class, in those whose fathers were automechanics or shipyard workers. Another part of the study showed that children residing in areas with heavy traffic also were at risk for increased lead retention. Thus, automobile exhausts and indirect occupational exposure appear to be important sources of lead retention in children, while a contribution from industrial emissions could not be detected.

Child↗
PubMed1990

Predictors of tooth-lead level with special reference to traffic. A study of lead-exposure in children.

Possible predictors of the lead burden of children were investigated in a low-exposure area. A total of 1302 school children in the first form within the municipality of Aarhus, Denmark, donated deciduous teeth for determination of the lead concentration in the circumpulpal dentin. The families were interviewed on possible sources of lead. Present and former addresses of residences and day-care institutions were obtained, and the traffic intensity was estimated at each of these addresses. Children with a high lead burden resided significantly more often in heavily-travelled streets than children with a low burden, but only during their first 3 years of life. The increased risk for a high lead burden was related to the traffic intensity in a dose-response manner. Further, children with a high lead burden more often exhibited pica, their mothers smoked more during pregnancy, and their fathers were more likely to work at a garage or shipyard. In a logistic multivariate regression, such parental occupation increased the risk for a high lead burden 1.5-fold (ORadj; P = 0.03), whereas tobacco and traffic each were of borderline significance (ORadj = 1.4, P = 0.08).

Air Pollutants↗
PubMed1990

Learning disabilities in children: significance of low-level lead-exposure and confounding factors.

The hypothesis that low-level lead absorption is a risk factor for learning disabilities in school children was examined in the municipality of Aarhus, Denmark. During 1982-1983, a total of 1,302 children in the first grade (54% of the eligible population) delivered shed deciduous teeth. The lead concentration in the circumpulpal dentin was used as an indicator of the cumulated lead absorption, and 200 cases (high-lead) and controls (low-lead) were selected, and matched for socioeconomic group and gender. The parents were interviewed regarding the child's development and past medical history. Possible confounders were identified and controlled for in a logistic multivariate model. The influence of lead absorption became statistically significant only after exclusion of the children with proven medical risk factors, thereby the adjusted odds ratio in the weighted analysis was changed from 2.2 to 4.3. Thus, in a Scandinavian low-level lead-polluted area, lead absorption appears to be a risk factor for learning disabilities.

Child↗
PubMed1990

Validity and interpretation of blood lead levels: a study of Danish school children.

Blood lead concentrations were measured in a group of children from a group of 9- to 10-year-old school children in Aarhus, Denmark. The study group was selected as a high-level and a low-level lead group, as identified by the lead concentration in the circumpulpal dentine in deciduous teeth shed 2-3 years previously. The validity of the blood sampling technique was investigated in adult volunteers, and lead was determined by electrothermal atomic absorption. Capillary blood sampling by a finger-stick method was preferred, as the slight contamination caused by this technique was deemed acceptable. The children with the highest dentine lead levels (n = 70), had blood lead concentrations of 0.08-0.63 mumol/l and a geometric mean of 0.28 mumol/l. The children with lowest dentine levels (n = 76) had blood lead concentrations of 0.08-0.70 mumol/l and a geometric mean of 0.18 mumol/l. The blood lead concentrations were compared with interview data on behaviour, family habits, diet, parents' tobacco smoking and occupation, water lead measurements, and traffic counts. A total of 20% of the variation in blood lead was explained by parents' tobacco smoking, the child's number in the sibship, gender, and consumption of canned food at home.

Adult↗
PubMed1988

Traffic a source of lead exposure in childhood.

Experimental and observational data has long implicated automobile exhaust from leaded petrol as a major source of human lead exposure. The present study evaluates the association of individual traffic exposure with individual lead absorption. A case-referent study was carried out on 1302 out of 2412 children in the municipality of Aarhus - Denmark. Shed deciduous teeth were matched for sex and socioeconomic status. Individual lead sources were assessed by an interview. Information on former addresses and the data of address change was obtained as was information on the daily number of cars driving on all roads of the city. A traffic index was constructed describing the traffic density at the home. An association between high lead and high traffic density was found in the children at the age of 6 months to 2 years. This relationship was of a dose-response nature. The association was not account for by other possible major sources.

Child↗
PubMed1978

Small metacentric nonsatellited extra chromosome: report of five mentally retarded individuals and review of literature. Contribution to further delineation of a new syndrome.

Five mentally retarded male patients with a supernumerary small metacentric nonsatellited chromosome were found to have many clinical features in common. The face showed characteristic small crowded features, the bodily habitus was asthenic, and the hands and feet had minor abnormalities. Renal anomalies were present in two patients. One patient had a myelomeningocele. Cytogenetic studies employing Q, R, and C banding in four patients showed the small extra chromosome to have staining properties compatible with an isochromosome of the short arm of chromosome 18. A comparison with previous case reports suggests a new syndrome. However, the identity of the extra chromosome has not yet been determined.

Adolescent↗
PubMed1977

[Triploidy].

Explore the source record for details and available documents.

Female↗
PubMed1975

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.

Adult↗
PubMedDate not supplied

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.

Animals↗