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Biomedical subjects

M Barr

Publications and source records attributed to M Barr.

At least 73 records · Page 4Linked to original sources
PubMed1991

Twin gestation: influence of placentation on fetal growth.

To study fetal growth in twin gestation, morphometric autopsy data of 52 midgestation twin pairs who were stillborn or who died less than or equal to 24 hours after birth were analyzed. Twins were divided into three groups: (1) monozygotic: diamniotic, monochorionic placenta (n = 18); (2) dizygotic: diamniotic, dichorionic placenta, unlike sex (n = 12); (3) like-sex: placenta diamniotic, dichorionic in 63.6%, unknown in 36.4% (n = 22). The monozygotic group had a significantly higher rate of growth discordance, which was defined as a greater than 20% difference in body weight (monozygotic 72.2%, dizygotic 16.7%, like-sex 0%), and polyhydramnios (monozygotic 50%, dizygotic 0%, like-sex 9.1%). Organ weight z scores for body weight and brain weight standards were calculated for the smaller and larger of each twin pair. In the monozygotic group highly significant z scores were obtained for brain weight in the smaller twin (z = 2.71, p = 0.003, body weight standards) and heart weight in the larger twin (body weight standards, z = 3.87, p less than 0.001; brain weight standards, z = 3.64, p less than 0.001). We conclude that monozygotic twins with diamniotic, monochorionic placentation have a high degree of brain-sparing growth restriction in the smaller twin and cardiac hyperplasia in the larger twin, most likely caused by hemodynamic inequalities.

Adolescent↗
PubMed1991

Records. Rights of access.

From 1 November 1991 clients will have right of access to their health records. Health visitor journal outlines the provisions of the Access to Health Records Act 1990; HVA professional officer Jane Naish examines the implications for health visitor and school nurse practice, and solicitor Melanie Barr describes the legal context.

Community Health Nursing↗
PubMed1990

An intron mutation in the human alpha 1(I) collagen gene alters the efficiency of pre-mRNA splicing and is associated with osteogenesis imperfecta type II.

This study describes a homozygous, G----A transition at the moderately conserved +5 position within the splice donor site of intron 14 in the human alpha 1(I) collagen gene. The mutation reduced the efficiency of normal splice-site selection since the exon upstream of the mutation was spliced alternatively. Moreover, the extent of alternative splicing was sensitive to the temperature at which the mutant cells were grown, suggesting that the mutation directly affected spliceosome assembly. To achieve exon skipping, this effect must be propagated so as to disrupt the selection of a second splice site in the adjacent intron.

Adenine↗
PubMed1990

Cytogenetic results of chorionic villus sampling: high success rate and diagnostic accuracy in the United States collaborative study.

Cytogenetic results of first-trimester chorionic villus sampling are reported from seven U.S. medical centers. For 6033 patients who had a successful chorionic villus sampling procedure, the rate for obtaining a cytogenetic diagnosis was 99.6% with the direct method, long-term culture, or both. There were no incorrect sex predictions and no diagnostic errors involving trisomies 21, 18, or 13, sex chromosome aneuploidies, or structural abnormalities. There were no cases of normal cytogenetic diagnosis followed by birth of a cytogenetically abnormal infant. Three cases of unusual aneuploidies (tetraploidy, trisomy 16, and trisomy 22) detected by the direct method only were not confirmed by cytogenetic follow-up. Mosaic cytogenetic abnormalities were observed in 0.83% of all cases in which chorionic villus sampling was done but were confirmed by amniocentesis or in fetal tissues in only 7 of 30 cases (23.3%). Maternal cell contamination occurred in 1.9% of long-term cultures, although this did not present any cytogenetic diagnostic difficulties. Overall, a very high degree of laboratory success and diagnostic accuracy was observed with either cytogenetic method, although fewer predictive errors were observed with the long-term culture method and none were observed when both methods were used.

Amniocentesis↗
PubMed1990

Periodontal disease in children with Down's syndrome.

The occurrence of supra- and subgingival calculus, gingival inflammation, periodontal pockets (greater than or equal to 5 mm) and alveolar bone loss was determined in children (10-19 yr) with Down's syndrome (D-S) and in an aged- and sex-matched control group (n = 39). Of D-S children (n = 71), 39 of the patients (mean age 15.5 yr) cooperated in a clinical and roentgenologic examination. Alveolar bone loss was determined around incisors and first molars on intraoral radiographs when the distance between cementoenamel junction (CEJ) to alveolar crest (AC) exceeded 2.0 mm. Alveolar bone loss was diagnosed in 39% of the D-S children compared to 3% in the control group (P less than 0.001). Of the total number of sites examined on radiographs the distance from CEJ to AC exceeded 2.0 mm in 8% in the D-S group compared to 0.2% in the control group (P less than 0.001). The frequency of sites with alveolar bone loss in D-S children was significantly (P less than 0.001) higher around the mandibular incisors compared to first molars. The study shows that early signs of periodontitis are frequently seen in D-S children as early as 11 yr of age and the lesions are first diagnosed in the mandibular anterior region.

Adolescent↗
PubMed1989

Ebstein's anomaly and extracardiac defects.

Ebstein's anomaly of the tricuspid valve occurs as an isolated defect with other forms of congenital heart disease such as transposition of the great arteries or tetralogy of Fallot or, rarely, in association with extracardiac malformations. Because so little is known about this latter group, we studied four cases clinically, at autopsy, and by means of a retrospective chart review. Major extracardiac changes most often involved the craniofacial region, central nervous system, and limbs. Karyotypes were normal, and no distinctive syndromes or anatomic patterns were identified. Since the timing of Ebstein's anomaly is quite precise, ascertainment of such cases on the basis of cardiac morphology may enhance the understanding of etiology and pathogenesis. Both causes and mechanisms may well be diverse, for the clinical histories and anatomic findings in present and previously reported cases vary considerably. Isolated Ebstein's anomaly may develop from topographically and temporally localized damage. Ebstein's anomaly with extracardiac defects may involve damage during a longer, and perhaps earlier, period.

Abnormalities, Multiple↗
PubMed1989

Symmetrical intrauterine growth retardation is not symmetrical: organ-specific gravimetric deficits in midtrimester and neonatal trisomy 18.

Models to predict normal fetal growth have been of limited accuracy. Abnormal growth is even more problematic. We have developed a mathematical modeling system based on observed body and brain weights to study fetal growth patterns in midgestational trisomy 18 fetuses. Third-degree polynomial-based analysis using observed fetal body and brain weights to generate predicted weights for various organ systems allows for the comparative study of growth patterns at various fetal weights and gestational ages. Our data suggest that what has been previously called symmetrical intrauterine growth retardation associated with aneuploid fetuses is really an asymmetrical pattern that is dynamic in nature and may change through the course of pregnancy.

Body Weight↗
PubMed1989

Utilization of screening mammography by primary care physicians.

Although mammography is the primary modality for the detection of early breast cancer, routine screening of asymptomatic women in the U.S. has not occurred. A survey of the referral practices for breast cancer screening of 513 Virginia primary care physicians was conducted. An average percentage of 39% of women age 35 to 40, 55% of women age 40 to 50, and 57% of women over age 50 were referred for screening mammography. Gynecologists referred the greatest number of women for screening. An increase of mammography referrals was repeated by 81% of physicians; 21% of physicians stated that they referred all women over 50 for screening. Half of the physicians believed that women in their community were unaware of the benefits of mammography screening. Major deterrents were the cost of mammography and the lack of third-party coverage.

Adult↗
PubMed1988

Disturbances in dental development after total body irradiation in bone marrow transplant recipients.

The dental status of 16 children who had been treated with bone marrow transplantation (BMT) for serious bone marrow diseases was followed for up to 6 years. Several types of disturbances in dental development were observed in children who had been conditioned with total body irradiation (TBI) at 10 Gy before BMT. Thus, impaired root development that caused short V-shaped roots was found in all patients, a complete failure of root development and premature apical closure were found in five patients, enamel hypoplasia was observed in four patients, and microdontia was observed in three patients conditioned with TBI. Patients younger than 6 years of age at BMT exhibited the most severe and extensive dental aberrations. The TBI at 10 Gy appeared to be the major cause of the disturbances found.

Abnormalities, Radiation-Induced↗