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Biomedical subjects

P Weihe

Publications and source records attributed to P Weihe.

30 records · Page 2Linked to original sources
PubMed1988

An epidemic outbreak of group B meningococcal disease on the Faroe Islands.

An epidemic of group B meningococcal disease on the Faroe Islands is described. A peak annual incidence of 95 cases/100,000 was reached in 1981. The time at which the epidemic commenced cannot be determined due to inadequate diagnostic facilities, but was presumably around the end of the 1970s. The incidence fell to 29 cases/100,000 in 1985, which indicates that the Faroe Islands are still a high incidence area. A total of 203 cases of meningococcal disease were recorded during the period 1978-1985 with 11 deaths (lethality rate 5.4%). After rifampicin was introduced in 1981 as prophylactic treatment against secondary cases, 1,892 persons were treated with this agent and none of these appeared in the study population. Before rifampicin prophylaxis was introduced, the number of cases were distributed with an evenly increasing incidence in the capital and in the provinces. Following the introduction of rifampicin as prophylactic agent, a fall in the incidence in both areas was observed. This fall was more pronounced in the capital, where the number of prescribed prophylactic doses per case of meningococcal disease was higher than in the province.

Adolescent↗
PubMed1988

Screening for complement deficiencies in patients surviving from epidemic meningococcal disease.

Sera from 132 patients surviving from meningococcal disease during the high-endemic period 1 January 1980 to 31 December 1984 on the Faroe Islands were screened for deficiencies of the complement (C) system by measuring hemolytic complement function in serum. Samples from 12 patients with reduced C function were further investigated by immunochemical quantification of individual C proteins. One patients was identified with C3-deficiency (C3-concentration 6% of normal) due to the presence of C3 nephritic factor (C3NeF) in serum. In addition, eight patients had minor aberrations in one or several complement proteins. It is concluded, that C deficiency is not an important risk factor during epidemics of meningococcal disease. The C3NeF activity could not be absorbed with Neisseria meningitidis group B, type 15, indicating absence of crossreactivity between neisserial antigens and C3NeF.

Complement C3 Nephritic Factor↗
PubMed1982

Hepatic microsomal enzyme function in technicians and anesthesiologists exposed to halothane and nitrous oxide.

It is controversial whether daily occupational exposure to halothane stimulates (induces) the hepatic microsomal enzyme function in man. We investigated two groups of persons with different degrees of exposure to halothane: Six technicians who for years had been employed with repair and control of anesthesiologic equipment resulting in exposure to about 7 ppm of halothane and 50 ppm of nitrous oxide, and seven anesthesiologists exposed during months to about 2 ppm of halothane and 75 ppm of nitrous oxide. The clearance of antipyrine was determined from saliva concentrations before and 4 wk after discontinuation of exposure. Matched control persons were investigated simultaneously. No significant differences were found between the half-life, apparent volume of distribution, or clearance of antipyrine either within the groups or between the groups. If the antipyrine data from both exposure groups are compared to those of the control groups, the data exclude (95% confidence limit) that antipyrine metabolism increased by more than 3% during exposure to waste anesthetics. This indicates that occupational exposure to halothane in concentrations above the proposed maximal time weighted average concentration of 2 ppm does not change the microsomal activity.

Adult↗
PubMedDate not supplied

Feasibility and validity of three computer-assisted neurobehavioral tests in 7-year-old children.

Three tests from the computerized Neurobehavioral Examination System (NES) were administered to a group of 917 Faroese children at approximately 7 years of age. The NES Continuous Performance Test (CPT) was modified to use animal silhouettes as stimuli instead of letters. Almost all children completed Finger Tapping (FT), the modified CPT, and Hand-Eye Coordination (HE). However, 18% of the children missed at least 25% of the stimuli on the CPT (full test period), and 37% of the children did not improve their HE performance by at least 10%, as compared to the first trial. Boys obtained better results than girls, and older children performed better than younger ones. However, both factors were confounded by acquaintance with computer games. Children who used glasses, who had strabismus, or who had decreased contrast sensitivity obtained less satisfactory scores, especially on CPT and HE. The NES performance was significantly associated with functional neurological performance, including catching a ball, diadochokinesia, and finger agnosia. Slight, though statistically significant, decrements were seen with increased levels of prenatal exposure to neurotoxicants, as indicated by the mercury concentrations in cord blood obtained at the time of birth. In conclusion, the tests were feasible in this age group after slight modifications, and the test results showed meaningful associations with major predictors, thus supporting the validity of the data.

Adolescent↗
PubMedDate not supplied

Impact of contrast sensitivity performance on visually presented neurobehavioral tests in mercury-exposed children.

Presentation of neuropsychological tests on a computer screen may involve a visual challenge to the examinee. The possible need for adjustment for visual contrast sensitivity on test performance was therefore determined from data on 917 mercury-exposed children who were examined at age 7 years. Contrast sensitivity was found to be associated with performance on the computer-assisted Continuous Performance Test. However, it showed similar associations with performance on traditional pencil-and-paper tests, especially Bender Visual Motor Gestalt Test and Wechsler Intelligence Scale for Children-Revised (WISC-R) Block Designs. Contrast sensitivity was not associated with prenatal mercury exposure, and adjustment for visual function had only a negligible effect on the regression coefficients for mercury as predictor of neuropsychological deficits. The mercury-associated neurobehavioral deficits are therefore unlikely to be due to mercury-induced visual system dysfunction causing secondary deficits in cognitive domain testing. Visuospatial processing appears to be a determinant in contrast sensitivity performance, and careful consideration of whether to control for contrast sensitivity in future studies of neurotoxicant effects is therefore recommended.

Bender-Gestalt Test↗
PubMedDate not supplied

Neurobehavioral deficits associated with PCB in 7-year-old children prenatally exposed to seafood neurotoxicants.

Prenatal exposure to polychlorinated biphenyls (PCBs) was examined by analysis of cord tissue from 435 children from a Faroese birth cohort. Analysis of 50 paired cord blood samples showed excellent correlation with the cord tissue concentration (r=.90). Among 17 neuropsychological outcomes determined at age 7 years, the cord PCB concentration was associated with deficits on the Boston Naming Test (without cues, two-tailed P=.09 not adjusted for mercury; with cues, P=.03), the Continuous Performance Test reaction time (P=.03), and, possibly, on long-term recall on the California Verbal Learning Test (P=.15). The association between cord PCB and cord-blood mercury (r=.42) suggested possible confounding. While no PCB effects were apparent in children with low mercury exposure, PCB-associated deficits within the highest tertile of mercury exposure indicated a possible interaction between the two neurotoxicants. PCB-associated increased thresholds were seen at two of eight frequencies on audiometry, but only on the left side, and no deficits occurred on evoked potentials or contrast sensitivity. The limited PCB-related neurotoxicity in this cohort appears to be affected by concomitant methylmercury exposure.

Child↗
PubMedDate not supplied

Cognitive deficit in 7-year-old children with prenatal exposure to methylmercury.

A cohort of 1022 consecutive singleton births was generated during 1986-1987 in the Faroe Islands. Increased methylmercury exposure from maternal consumption of pilot whale meat was indicated by mercury concentrations in cord blood and maternal hair. At approximately 7 years of age, 917 of the children underwent detailed neurobehavioral examination. Neuropsychological tests included Finger Tapping; Hand-Eye Coordination; reaction time on a Continuous Performance Test; Wechsler Intelligence Scale for Children-Revised Digit Spans, Similarities, and Block Designs; Bender Visual Motor Gestalt Test; Boston Naming Test; and California Verbal Learning Test (Children). Clinical examination and neurophysiological testing did not reveal any clear-cut mercury-related abnormalities. However, mercury-related neuropsychological dysfunctions were most pronounced in the domains of language, attention, and memory, and to a lesser extent in visuospatial and motor functions. These associations remained after adjustment for covariates and after exclusion of children with maternal hair mercury concentrations above 10 microgram(s) (50 nmol/g). The effects on brain function associated with prenatal methylmercury exposure therefore appear widespread, and early dysfunction is detectable at exposure levels currently considered safe.

Adult↗
PubMedDate not supplied

Delayed evoked potentials in children exposed to methylmercury from seafood.

Methylmercury poisoning may cause constriction of visual fields and deafness, especially if exposure occurs prenatally. However, the risks associated with exposure from contaminated seafood is unclear. We examined 149 children attending first grade in a Madeiran fishing community. As maternal dietary habits were relatively unchanged, current maternal hair concentrations were used as indicator of the child's prenatal exposure to methylmercury (geometric average, 9.64 microg/g [48.2 nmol/g]). After adjustment for age and sex, the mean (+/-SD) latency of peak III of the brainstem auditory evoked potentials at 40 Hz was increased by 0.128+/-0.047 ms when maternal hair-mercury concentrations exceeded 10 microg/g (50 nmol/g) (p for association, 0.002), and the increase of the N145 pattern-reversal visual evoked potential latency at 15 minutes of arc was 3.16+/-1.57 ms (p for association, 0.002). No such relationships were seen with the child's own hair-mercury concentration, and other clinical examinations revealed no mercury-associated deficits. Neurophysiological evidence of adverse effects on brain function are relatively independent of confounders, and should be considered in the risk assessment of this seafood pollutant.

Child↗
PubMedDate not supplied

Evoked potentials in Faroese children prenatally exposed to methylmercury.

A study of 7-year-old children from a fishing village on Madeira has suggested that latencies of evoked potentials may be delayed because of increased exposures to methylmercury during development. Data from a previously published prospective study in the Faroe Islands have therefore been reexamined. Because of changes in instrumentation, results obtained during the second year of examination were excluded. After this restriction, the results show significant mercury-associated delays of the peak III latency and the I-III interpeak latency of the auditory brainstem evoked potentials. Mercury concentrations in both maternal hair at parturition and in cord blood indicated this association, whereas no such relationship was apparent with the child's current hair-mercury concentration. Thus, in agreement with the findings from Madeira, a delay of the peak III latency of the brainstem auditory evoked potentials appears to serve as a marker of prenatal methylmercury toxicity from contaminated seafood.

Atlantic Islands↗
PubMedDate not supplied

Impact of maternal seafood diet on fetal exposure to mercury, selenium, and lead.

Umbilical cord blood from 1,023 consecutive births in the Faroe Islands showed a median blood-mercury concentration of 121 nmol/l (24.2 micrograms/l); 250 of those samples (25.1%) had blood-mercury concentrations that exceeded 200 nmol/l (40 micrograms/l). Maternal hair mercury concentrations showed a median of 22.5 nmol/g (4.5 micrograms/g), and 130 samples (12.7%) contained concentrations that exceeded 50 nmol/g (10 micrograms/g). Frequent ingestion of whale meat dinners during pregnancy and, to a much lesser degree, frequent consumption of fish, and increased parity or age were associated with high mercury concentrations in cord blood and hair. Blood-mercury levels were slightly lower if the mother had occasionally ingested alcoholic beverages. Mercury in blood correlated moderately with blood selenium (median, 1.40 mumol/l). Increased selenium concentrations were associated with intake of whale meat, alcohol abstention, delivery after term, and high parity. Lead in cord blood was low (median, 82 nmol/l), particularly if the mothers had frequently had fish for dinner and had abstained from smoking.

Alcohol Drinking↗