A 9.6 kilobase deletion in the low density lipoprotein receptor gene in Norwegian familial hypercholesterolemia subjects

Haplotype analysis of the low density lipoprotein receptor (LDLR) gene was performed in Norwegian subjects heterozygous for familial hypercholesterolemia (FH). Southern blot analysis of genomic DNA, using an exon 18 specific probe and the restriction enzyme NcoI, showed that two out of 57 unrelated FH subjects had an abnormal 3.6 kb band. Further analyses revealed that this abnormal band was due to a 9.6 kb deletion that included exons 16 and 17. The 5' deletion breakpoint was after 245 bp of intron 15, and the 3' deletion breakpoint was in exon 18 after nucleotide 3390 of cDNA. Thus, both the membrane-spanning and cytoplasmatic domains of the receptor had been deleted. A polymerase chain reaction (PCR) method was developed to identify this deletion among other Norwegian FH subjects. As a result of this screening one additional subject was found out of 124 subjects screened. Thus, three out of 181 (1.7%) unrelated Norwegian FH subject possessed this deletion. The deletion was found on the same haplotype in the three unrelated subjects, suggesting a common mutagenic event. The deletion is identical to a deletion (FH-Helsinki) that is very common among Finnish FH subjects. However, it is not yet known whether the mutations evolved separately in the two countries.     

Evaluation of the Determine Rapid Syphilis TP assay using sera

The Abbott Determine Rapid Syphilis TP assay is a treponemal test that can be used in resource-poor settings that lack laboratory facilities. However, this test has not been extensively evaluated. We measured its sensitivity and specificity by using stored serum specimens (n = 567) from all persons who tested Treponema pallidum hemagglutination assay (TPHA) positive (n = 250) or TPHA indeterminate (n = 17) in the year 2001 and the first 300 patients in 2001 who tested TPHA negative at the Evandro Chagas Research Institute in Rio de Janeiro, Brazil. This rapid assay was independently interpreted by three different observers. With TPHA results as the reference, sensitivity ranged between readers from 95.6 to 98.4% and specificity ranged from 97.3 to 95.7%. There was little interreader variability in the interpretation of results, with approximately 98% agreement for all reader combinations. Of samples from persons with human immunodeficiency virus (HIV) infection (n = 198), sensitivity was 96.9 to 99.2% and it was 94.4 to 96.3% among HIV-negative persons (n = 127). Specificity was 92.4 to 95.5% among HIV-positive persons and 97.2 to 100% among HIV-negative persons. We found this test to have high sensitivity and specificity and little interreader variability, indicating that it may be easily used in resource-poor settings without laboratory facilities. Further studies are needed using this test on whole blood and under the clinical conditions for which it is intended.     

Correlation between fluorescence in-situ hybridization analyses and in-vitro development to blastocyst stage of embryos from Robertsonian translocation (13;14) carriers

BACKGROUND: Little is known about the extent and timing of selection against the embryos that are carriers of unbalanced translocations. METHODS: Fluorescence in-situ hybridization (FISH) with probes for chromosomes 13, 14 and 18 was performed, mostly on day 3, on 69 human embryos which were then allowed to develop further in culture to day 5, from five carriers of Robertsonian translocation (RT) t(13;14). RESULTS: Twelve normal/balanced blastocysts were replaced in seven consecutive cycles (day 5). Three cycles resulted in clinical pregnancies. The proportion of blastocysts displaying a normal/balanced karyotype was 56%, while only the 20% of blocked embryos were normal/balanced (chi(2): P < 0.05). All the embryos analysed on day 5, except one, displayed mosaicism. The percentages of diploid cells for chromosomes 13 and 14 were significantly lower than for chromosome 18 (chromosome 13: 49.0 +/- 28.0; chromosome 14: 53.0 +/- 31.8; chromosome 18: 75.7 +/- 20.4; Mann-Whitney test: P < 0.01). The embryos displaying vertical line 62% of diploid cells for at least two of the three chromosomes analysed, more frequently reached the blastocyst stage (blocked embryos: blastocysts chromosome 13: 43.1 +/- 30.3, 64.9 +/- 29.0; chromosome 18: 64.9 +/- 29.0, 83.0 +/- 12.9; Mann-Whitney test: P < 0.01). CONCLUSIONS: Normal/balanced embryos developed better but the proportion of abnormal blastocysts was still high. Preimplantation genetic diagnosis is recommended to select normal/balanced embryos from RT t(13;14) carriers.     

Continuity, discontinuity, and coherence in attachment from infancy to late adolescence: sequelae of organization and disorganization

This longitudinal study examines continuity and discontinuity of attachment quality from infancy to late adolescence in a sample of 125 participants considered at birth to be at high-risk due to poverty. Strange Situations were conducted at 12 and 18 months; Adult Attachment Interviews were administered at age 19. Child and maternal characteristics and experiences and observational assessments of the families were explored as correlates of continuity and discontinuity in attachment. Contrary to findings of continuity from low-risk samples, analyses demonstrated no significant overall continuity in attachment security. Disorganized infants were significantly more likely than organized infants to be insecure or unresolved in late adolescence. Additionally, infant disorganization predicted unresolved abuse scores on the AAI for those participants who experienced childhood abuse. Significant correlates of continuity and change spanned a variety of age periods and included infant temperament, maternal life stress, family functioning at pre-adolescence, child maltreatment and features of the home environment. Findings are discussed as supporting the coherence of attachment over time.     

Ultrastructural comparison of hydroxyapatite and silicon-substituted hydroxyapatite for biomedical applications

Silicon-substituted hydroxyapatite (Si-HA) has been shown to lead to significantly increased rates of bone apposition when compared with phase-pure hydroxyapatite (HA) bioceramic implants (Patel N, et al. J Mater Sci Mater Med 2002;13:1199-1206). However, uncertainty remains about the mechanism by which Si increases the in vivo bioactivity. In this study, defect structures in Si-HA were observed and characterized for the first time using high-resolution transmission electron microscopy. Using tilting experiments and the g. b = 0 criterion for invisibility, the Burgers vectors of dislocations in phase-pure HA and 0.8 wt % Si-HA were characterized to be screw and mixed in character. Dislocations were observed in both pure HA and 0.8 wt % Si-HA with no significant difference in dislocation density between HA and Si-HA. However, our findings suggest that an increased number of triple junctions in Si-HA may have a significant role in increasing the solubility of the material and the subsequent rate at which bone apposes Si-HA ceramics.