Ultrasound features in trisomy 13 (Patau syndrome) and trisomy 18 (Edwards syndrome) in a consecutive series of 47 cases.

OBJECTIVE: To determine and list the variety of the predominant appeal signs leading to referral and their accompanying features found during specialized ultrasound evaluation in foetuses with trisomy 13 and trisomy 18. MATERIALS AND METHODS: In a period of thirty years, 1110 cases of foetal malformations were detected during specialized echographic evaluation. 47 Of these cases were foetuses with trisomy 13 or trisomy 18. We evaluated the predominant signs leading to referral, the difference and overlap in presenting signs between both syndromes and when the data were available, we also compared the echographic signs with the foetal pathology. RESULTS: In foetuses with trisomy 13 the most common malformations were craniofacial defects, cerebral malformations and genitourinary tract anomalies. The most common malformations associated with trisomy 18 were limb abnormalities and intrauterine growth restriction. Most malformations were predominant in trisomy 18, except for genitourinary tract anomalies. In most cases the sonographic signs correlated with the pathology findings. CONCLUSION: Trisomy 13 as well as trisomy 18 are characterized by a number of various malformations in the foetus. Most of the ultrasound features were predominant in foetuses with trisomy 18. Mostly the foetal pathology correlated with the sonographic evaluation.

Bacterial diversity within the human subgingival crevice.

Molecular, sequence-based environmental surveys of microorganisms have revealed a large degree of previously uncharacterized diversity. However, nearly all studies of the human endogenous bacterial flora have relied on cultivation and biochemical characterization of the resident organisms. We used molecular methods to characterize the breadth of bacterial diversity within the human subgingival crevice by comparing 264 small subunit rDNA sequences from 21 clone libraries created with products amplified directly from subgingival plaque, with sequences obtained from bacteria that were cultivated from the same specimen, as well as with sequences available in public databases. The majority (52.5%) of the directly amplified 16S rRNA sequences were <99% identical to sequences within public databases. In contrast, only 21.4% of the sequences recovered from cultivated bacteria showed this degree of variability. The 16S rDNA sequences recovered by direct amplification were also more deeply divergent; 13.5% of the amplified sequences were more than 5% nonidentical to any known sequence, a level of dissimilarity that is often found between members of different genera. None of the cultivated sequences exhibited this degree of sequence dissimilarity. Finally, direct amplification of 16S rDNA yielded a more diverse view of the subgingival bacterial flora than did cultivation. Our data suggest that a significant proportion of the resident human bacterial flora remain poorly characterized, even within this well studied and familiar microbial environment.

A single copy of apolipoprotein B-48 is present on the human chylomicron remnant.

Individuals homozygous for the e2 allele encoding apolipoprotein E exhibit a remnant removal defect and accumulate substantial levels of intestinally derived particles containing apolipoprotein B-48 (apoB-48). Such lipoproteins were isolated from the plasma of E2/E2 individuals, and further purified by affinity chromatography using a polyclonal antibody specific for selective binding and removal of apoB-100-containing lipoproteins. The unbound lipoproteins, termed chylomicron remnants, were particles with average hydrated diameters of 31.2 nm as determined by dynamic light scattering. They contained apoB-48 and ApoE as their only protein components. The number of apoB-48 molecules on each lipoprotein was assessed by counting the number of antibody molecules bound to the surface of the chylomicron remnants, using either a monoclonal antibody specific for a single epitope on apoB-48 or a mixture of two such monoclonal antibodies specific for widely separated epitopes. The results of this analysis seem unambiguous: no more than one apoB-48 resides on the chylomicron remnant. Because apoB appears to be unable to transfer among lipoprotein particles, it may be inferred that nascent chylomicrons also contain a single copy of apoB-48.