Effect of plasma TNF-alpha on filgrastim-stimulated hematopoiesis in mice and humans

Marshall syndrome is a rare, autosomal dominant skeletal dysplasia that is phenotypically similar to the more common disorder Stickler syndrome. For a large kindred with Marshall syndrome, we demonstrate a splice-donor-site mutation in the COL11A1 gene that cosegregates with the phenotype. The G+1-->A transition causes in-frame skipping of a 54-bp exon and deletes amino acids 726-743 from the major triple-helical domain of the alpha1(XI) collagen polypeptide. The data support the hypothesis that the alpha1(XI) collagen polypeptide has an important role in skeletal morphogenesis that extends beyond its contribution to structural integrity of the cartilage extracellular matrix. Our results also demonstrate allelism of Marshall syndrome with the subset of Stickler syndrome families associated with COL11A1 mutations.     

Studies of bioaccumulation and biotransformation of PCBs in mustelids based on concentration and congener patterns in predators and preys

Bioaccumulation of non-, mono-, and di-ortho-substituted chlorobiphenyls (CBs) was investigated in four species of mustelids (weasel, stoat, polecat, and otter) and their preys, from a restricted area in the northern part of The Netherlands. Diets of these mustelids ranged from terrestrial (weasel, stoat, and polecat) to aquatic (otter). Diet-specific biomagnification factors (BMFs), CB in diet relative to CB in mustelids, were calculated for the sum of 28 congeners (SigmaCB), for the sum of the toxic equivalent concentration (SigmaTEQ) and on an individual congener basis. Biotransformation was studied in relation to structural CB properties (vicinal H-atom substitution). In addition, the methylsulphonyl CB-metabolites were determined. The concentration of SigmaCB on lipid weight basis increased in the order weasel < stoat < polecat < otter. On the basis of SigmaTEQ, the order changed to weasel < polecat < stoat < otter. Most of the differences in BMFs between the CBs could be explained by the vicinal H-atom structure-activity rules. For all mustelids, the lowest BMFs were found for congeners with vicinal H-atoms in the meta, para position. Indications were found that all mustelid species can metabolize these congeners. For some of the CBs, their methylsulphonyl-CB metabolites were determined and found to be present in concentrations up to 350-fold higher than those of the parent compounds. In addition, the non-ortho CBs 126 and 169 are selectively retained in the liver of weasel, stoat, and otter. These CBs had the highest BMFs of all congeners. However, rather surprisingly, in polecat the highest BMFs were found for di-ortho-substituted CBs. This animal was able to metabolize all congeners with vicinal H-atoms in the ortho and meta position (non- and mono-ortho CBs). The information concerning the differences in bioaccumulation of CBs for closely related mustelid species increased the understanding of reported differences in PCB toxicity between mink and ferrets, and suggest that weasel, stoat, and otter are at least as sensitive to CBs as are mink, while polecats are less sensitive. As otter is exposed to much higher concentrations of CBs trough their diet than weasel and stoat, the toxic threat of CBs will be the greatest for this animal.     

Mismatch repair of heteroduplex DNA intermediates of extrachromosomal recombination in mammalian cells

Previous work indicated that extrachromosomal recombination in mammalian cells could be explained by the single-strand annealing (SSA) model. This model predicts that extrachromosomal recombination leads to nonconservative crossover products and that heteroduplex DNA (hDNA) is formed by annealing of complementary single strands. Mismatched bases in hDNA may subsequently be repaired to wild-type or mutant sequences, or they may remain unrepaired and segregate following DNA replication. We describe a system to examine the formation and mismatch repair of hDNA in recombination intermediates. Our results are consistent with extrachromosomal recombination occurring via SSA and producing crossover recombinant products. As predicted by the SSA model, hDNA was present in double-strand break-induced recombination intermediates. By placing either silent or frameshift mutations in the predicted hDNA region, we have shown that mismatches are efficiently repaired prior to DNA replication.     

Transgenic DNA integrated into the oat genome is frequently interspersed by host DNA

Integration of transgenic DNA into the plant genome was investigated in 13 transgenic oat (Avena sativa L.) lines produced using microprojectile bombardment with one or two cotransformed plasmids. In all transformation events, the transgenic DNA integrated into the plant genome consisted of intact transgene copies that were accompanied by multiple, rearranged, and/or truncated transgene fragments. All fragments of transgenic DNA cosegregated, indicating that they were integrated at single gene loci. Analysis of the structure of the transgenic loci indicated that the transgenic DNA was interspersed by the host genomic DNA. The number of insertions of transgenic DNA within the transgene loci varied from 2 to 12 among the 13 lines. Restriction endonucleases that do not cleave the introduced plasmids produced restriction fragments ranging from 3.6 to about 60 kb in length hybridizing to a probe comprising the introduced plasmids. Although the size of the interspersing host DNA within the transgene locus is unknown, the sizes of the transgene-hybridizing restriction fragments indicated that the entire transgene locus must be at least from 35-280 kb. The observation that all transgenic lines analyzed exhibited genomic interspersion of multiple clustered transgenes suggests a predominating integration mechanism. We propose that transgene integration at multiple clustered DNA replication forks could account for the observed interspersion of transgenic DNA with host genomic DNA within transgenic loci.     

Ventricular interdependence: significant left ventricular contributions to right ventricular systolic function

This article reviews diastolic and systolic ventricular interaction, and clinical pathophysiological conditions involving ventricular interaction. Diastolic ventricular interdependence is present on a moment-to-moment, beat-to-beat basis, and the interactions are large enough to be of physiological and pathophysiological importance. Although always present, ventricular interdependence is most apparent with sudden postural and respiratory changes in ventricular volume. Left ventricular function significantly affects right ventricular systolic function. Experimental studies have shown that about 20% to 40% of the right ventricular systolic pressure and volume outflow result from left ventricular contraction. This dependency of the right ventricle on the left ventricle helps to explain the right ventricular response to volume overload, pressure overload, and myocardial ischemia. The septum and its position are not the sole mechanism for ventricular interdependence. Ventricular interdependence causes overall ventricular deformation, and is probably best explained by the balance of forces at the interventricular sulcus, the material properties, and cardiac dimensions.     

The nondigestible fat sucrose polyester does not stimulate gallbladder emptying in humans

BACKGROUND: We determined the effect of oral ingestion of sucrose polyester, which was approved as a fat replacer in the United States, on gallbladder motility and on the release of cholecystokinin, the hormone that mediates gallbladder emptying. OBJECTIVE: Our objective was to measure effects of sucrose polyester on gallbladder emptying and cholecystokinin release. DESIGN: Eight healthy volunteers (3 men and 5 women) drank 60 mL sucrose polyester, digestible fat, or saline solution in a balanced crossover design on 3 separate days. RESULTS: Mean (+/-SEM) gallbladder emptying, when integrated over time, was low in response to both sucrose polyester (-150 +/- 214 mL x 120 min) and saline solution (-89 +/- 123 mL x 120 min). In contrast, there was marked emptying in response to digestible fat (1069 +/- 253 mL x 120 min). Sucrose polyester did not affect plasma cholecystokinin concentrations (-9.3 +/- 15.0 pmol x 120 min/L), whereas digestible fat resulted in a significant increase (89.5 +/- 44.8 pmol x 120 min/L, P = 0.014) compared with saline solution (-3.0 +/- 13.8 pmol x 120 min/L). CONCLUSIONS: Ingestion of sucrose polyester, in contrast with digestible fat, did not stimulate gallbladder emptying or release of cholecystokinin.