A noninvasive method for estimating cardiac output using lung to finger circulation time of oxygen.

To develop a safe, noninvasive, simple, inexpensive, and clinically adaptable method for estimating cardiac output, we evaluated the potential of lung to finger circulation time (LFCT) and buildup time (Tb) of oxygen as measured by pulse oximetry to estimate cardiac output. Significant correlation was found between cardiac output as measured by thermodilution and the inverse of LFCT (R = 0.76, p < 0.001, SEE = 0.9 L/min) as well as the inverse of Tb (R = 0.72, p < 0.001, SEE = 0.9 L/min).

The effects of Lactobacillus strains and oat fiber on methotrexate-induced enterocolitis in rats.

BACKGROUND & AIMS: Administration of methotrexate to rats on an elemental diet results in severe enterocolitis and death. Lactobacilli, an integral part of the healthy gastrointestinal microecology, may provide therapeutic benefits to help the recovery from enterocolitis. The purpose of this study was to evaluate the effects of lactobacilli and oatbase on methotrexate-induced enterocolitis in rats. METHODS: Rats received continuous intragastric infusion of elemental diet or with supplementation of oatbase, Lactobacillus reuteri R2LC, and Lactobacillus plantarum DSM 9843, with and without fermentation, from the beginning of the study. Methotrexate (20 mg/kg) was injected intraperitoneally on day 3, and the sampling was performed on day 6. RESULTS: Lactobacilli and oatbase decreased body weight loss and intestinal permeability and increased bowel mucosal mass in enterocolitic rats. Administration of lactobacilli, but not oatbase, decreased the intestinal myeloperoxidase level, reestablished intestinal microecology, and reduced bacterial translocation to extraintestinal sites. Both lactobacilli and oatbase reduced plasma endotoxin levels. The effects of lactobacilli were greater with fermentation than without fermentation or oatbase alone, and L. plantarum was more effective in reducing intestinal pathogens than L. reuteri. CONCLUSIONS: Exogenous administration of lactobacilli, especially L. plantarum with fermentation, is helpful in reducing the severity of enterocolitis in rats.

Pectin-supplemented enteral diet reduces the severity of methotrexate induced enterocolitis in rats.

BACKGROUND: Administration of methotrexate (MTX) to rats fed an elemental diet results in a high mortality from severe enterocolitis. Previous studies have shown that pectin is an important precursor of substrates for intestinal structure and function and may facilitate intestinal recovery after enterocolitis. The aim of this study is to evaluate the effect of pectin on MTX-induced enterocolitis in rats. METHODS: Rats received intragastric infusion of either 1% pectin-supplemented or pectin-free elemental diet from the beginning of the study via a gastrostomy. On the 4th day animals received either MTX, 20 mg/kg intraperitoneally, or saline injection and were killed on the 7th day for sampling. RESULTS: Pectin supplementation significantly decreased body weight loss, organ water content, and intestinal myeloperoxidase levels and increased mucosal protein, DNA, and RNA content in enterocolitis rats. The intestinal permeability was increased by administration of MTX, and pectin supplementation significantly reversed the increased permeability in the distal small bowel and colon. Pectin supplementation also lowered the magnitude of bacterial translocation, decreased plasma endotoxin levels, and restored bowel microecology. CONCLUSIONS: Pectin significantly decreased MTX-induced intestinal injury and improved bowel integrity.

DNA organization and polymorphism of a wild-type Drosophila telomere region.

Telomeres at the ends of linear chromosomes of eukaryotes protect the chromosome termini from degradation and fusion. While telomeric replication/elongation mechanisms have been studied extensively, the functions of subterminal sequences are less well understood. In general, subterminal regions can be quite polymorphic, varying in size from organism to organism, and differing among chromosomes within an organism. The subterminal regions of Drosophila melanogaster are not well characterized today, and it is not known which and how many different components they contain. Here we present the molecular characterization of DNA components and their organization in the subterminal region of the left arm of chromosome 2 of the Oregon RC wild-type strain of D. melanogaster, including a minisatellite with a 457bp repeat length. Two distinct polymorphic arrangements at 2L were found and analyzed, supporting the Drosophila telomere elongation model by retrotransposition. The high incidence of terminal chromosome deficiencies occurring in natural Drosophila populations is discussed in view of the telomere structure at 2L.

Comparison of two active HeT-A retroposons of Drosophila melanogaster.

HeT-A elements are Drosophila melanogaster LINE-like retroposons that transpose to broken chromosome ends by attaching themselves with an oligo(A) tail. Since this family of elements is believed to be involved in the vital function of telomere elongation in Drosophila, it is important to understand their transposition mechanism and the molecular aspects of activity. By comparison of several elements we have defined here the unit length of HeT-A elements to be approximately 6 kb. Also, we studied an active HeT-A element that had transposed very recently to the end of a terminally deleted X chromosome. The 12 kb of newly transposed DNA consisted of a tandem array of three different HeT-A elements joined by oligo(A) tails to each other and to the chromosome end broken in the yellow gene. Such an array may have transposed as a single unit or resulted from rapid successive transpositions of individual HeT-A elements. By sequence comparison with another recently transposed HeT-A element, conserved domains in the single open reading frame (ORF), encoding a gag-like polypeptide, of these elements were defined. We conclude that for transposition an intact ORF is required in cis, while the reverse transcriptase is not encoded on the HeT-A element but is provided in trans. This would make HeT-A elements dependent on an external reverse transcriptase for transposition and establish control of the genome over the activity of HeT-A elements. This distinguishes the Drosophila HeT-A element, which has been implicated in Drosophila telomere elongation, from the other, 'selfish' LINE-like elements.

The genomic organization of HeT-A retroposons in Drosophila melanogaster.

Members of the Drosophila HeT-A family of transposable elements are LINE-like retroposons that are found at telomeres and in centric heterochromatin. We recently characterized an active HeT-A element that had transposed to a broken chromosome end fewer than nine generations before it was isolated. The sequence arrangement of this element, called 9D4, most likely represents the organization of an actively transposing member of the HeT-A family. Here we assess the degree of divergence among members of the HeT-A family and test a model of telomere length maintenance based on HeT-A transposition. The region containing the single open reading frame of this element appears to be more highly conserved than the non-coding regions. The HeT-A element has been implicated in the Drosophila telomere elongation process, because frequent transpositions to chromosome ends are sufficient to counter-balance nucleotide loss due to incomplete DNA replication. The proposed elongation model and the hypothetical mechanism of HeT-A transposition predict a predominant orientation of HeT-A elements with their oligo (A) tails facing proximally at chromosome ends, as well as the existence of irregular tandem arrays of HeT-A elements at chromosome ends resulting from transposition of new HeT-A elements onto chromosome ends with existing elements. Twenty-nine different HeT-A fragments were isolated from directional libraries that were enriched in terminal DNA fragments. Sequence analyses of these fragments and comparisons with the organization of the HeT-A element, 9D4, fit these two predictions and support the model of Drosophila telomere elongation by transposition of HeT-A elements.

Frequent transpositions of Drosophila melanogaster HeT-A transposable elements to receding chromosome ends.

HeT-A elements are a new family of transposable elements in Drosophila that are found exclusively in telomeric regions and in the pericentric heterochromatin. Transposition of these elements onto broken chromosome ends has been implicated in chromosome healing. To monitor the fate of HeT-A elements that had attached to broken ends of the X chromosome, we examined individual X chromosomes from a defined population over a period of 17 generations. The ends of the X chromosomes with new HeT-A additions receded at the same rate as the broken ends before the HeT-A elements attached. In addition, some chromosomes, approximately 1% per generation, had acquired new HeT-A sequences of an average of 6 kb at their ends with oligo(A) tails at the junctions. Thus, the rate of addition of new material per generation matches the observed rate of terminal loss (70-75 bp) caused by incomplete replication at the end of the DNA molecule. One such recently transposed HeT-A element which is at least 12 kb in length has been examined in detail. It contains a single open reading frame of 2.8 kb which codes for a gag-like protein.