Lap18 is a highly conserved cytosolic protein that is expressed in dividing cells. Data from a number of studies show that a range of cell lines and mitogen-stimulated normal cells cultured in PMA phosphorylate and subsequently down-regulate Lap18. This has been found to be associated with growth arrest, although it is not clear that these events are causally related. In the present study we confirm that the HL60 promyelocytic leukemia and K562 erythroleukemia cell lines, when cultured with PMA, behave in this manner. This was not the case for any of five mouse plasmacytoma cell lines and six lines derived from patients with multiple myeloma or plasma cell leukemia. All of these lines contain Lap18, although the level of this protein in the mouse but not the human plasmacytoma cell-line cells is relatively low. All the neoplastic plasma cell-line cells phosphorylate Lap18 on culture with PMA, but this does not induce growth arrest nor result in down-regulation of Lap18 expression. Further experiments are required to test whether there is a mechanistic relationship between the continued growth of plasmacytoma cell lines and their failure to down-regulate Lap18 on culture in PMA.

Animals↗

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Static and dynamic function of the lower esophageal sphincter before and after laparoscopic Nissen fundoplication.

The means by which fundoplication protects against reflux is disputed. We studied the resting and dynamic features of the lower esophageal sphincter (LES) and 24-hour pH monitoring in 26 patients before and after laparoscopic Nissen fundoplication. Resting features were LES pressure, abdominal length, and total length. Dynamic function was assessed by the residual pressure in the LES during a swallow measured as the bolus flowed though the LES. All patients experienced near-total relief of heartburn and all but one had normal postoperative acid scores. Resting LES characteristics were restored to normal. Mean residual pressure on swallowing was 7.1+/-3.2 mm Hg in the patients postoperatively compared with 1.2+/-1 mm Hg preoperatively and 4.0+/-2.4 mm Hg in normal subjects. Eighteen of 26 patients had residual LES pressure within the normal range (<8.2 mm Hg). There was a tendency for residual pressures to be lower as experience with the procedure was gained. Incomplete LES relaxation is not necessary for effective functioning of a Nissen fundoplication. In construction of a Nissen fundoplication, creating a large retroesophageal window and deliberate dissection of the back of the posterior fundus from the left crus allows the creation of an effective antireflux procedure with restoration of static LES parameters to normal and minimal limitation of LES relaxation.

Adult↗

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Tracking the evolution of the elusive Andean mountain cat (Oreailurus jacobita) from mitochondrial DNA.

Rarely observed in the wild, the existence of the Andean mountain cat (Oreailurus jacobita) has been established based on only 3 skulls and 14 museum skins. The Andean mountain cat's evolutionary relationship to other felids based on morphological characters is largely contradictory, with evidence aligning it with South American small spotted cats (ocelot lineage) or alternatively with pantherine lineage felids. Here we describe the phylogenetic distinctiveness and placement of the Andean mountain cat using DNA extracted from pieces of nine independent pelt specimens, including one confiscated from a trapper in 1995. A phylogenetic analysis of DNA sequences from three rapidly evolving mitochondrial genes (16S rRNA, NADH-5, and ATP-8) indicate that the Andean mountain cat is a distinct species belonging to the ocelot lineage. Our findings suggest that the Andean mountain cat diverged from a common ancestor with the ocelot (Leopardus paradalis) and margay (L. wiedii) and exhibits moderate levels of genetic variation.

Animals↗

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Genomic ancestry of the American puma (Puma concolor).

Puma concolor, a large American cat species, occupies the most extensive range of any New World terrestrial mammal, spanning 110 degrees of latitude from the Canadian Yukon to the Straits of Magellan. Until the recent Holocene, pumas coexisted with a diverse array of carnivores including the American lion (Panthera atrox), the North American cheetah (Miracynonyx trumani), and the saber toothed tiger (Smilodon fatalis). Genomic DNA specimens from 315 pumas of specified geographic origin (261 contemporary and 54 museum specimens) were collected for molecular genetic and phylogenetic analyses of three mitochondrial gene sequences (16S rRNA, ATPase-8, and NADH-5) plus composite microsatellite genotypes (10 feline loci). Six phylogeographic groupings or subspecies were resolved, and the entire North American population (186 individuals from 15 previously named subspecies) was genetically homogeneous in overall variation relative to central and South American populations. The marked uniformity of mtDNA and a reduction in microsatellite allele size expansion indicates that North American pumas derive from a recent (late Pleistocene circa 10,000 years ago) replacement and recolonization by a small number of founders who themselves originated from a centrum of puma genetic diversity in eastern South America 200,000-300,000 years ago. The recolonization of North American pumas was coincident with a massive late Pleistocene extinction event that eliminated 80% of large vertebrates in North America and may have extirpated pumas from that continent as well.

Americas↗

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Phylogenetic and phylogeographic analysis of Iberian lynx populations.

The Iberian lynx (Lynx pardinus), one of the world's most endangered cat species, is vulnerable due to habitat loss, increased fragmentation of populations, and precipitous demographic reductions. An understanding of Iberian lynx evolutionary history is necessary to develop rational management plans for the species. Our objectives were to assess Iberian lynx genetic diversity at three evolutionary timescales. First we analyzed mitochondrial DNA (mtDNA) sequence variation to position the Iberian lynx relative to other species of the genus LYNX: We then assessed the pattern of mtDNA variation of isolated populations across the Iberian Peninsula. Finally we estimated levels of gene flow between two of the most important remaining lynx populations (Doñana National Park and the Sierra Morena Mountains) and characterized the extent of microsatellite locus variation in these populations. Phylogenetic analyses of 1613 bp of mtDNA sequence variation supports the hypothesis that the Iberian lynx, Eurasian lynx, and Canadian lynx diverged within a short time period around 1.53-1.68 million years ago, and that the Iberian lynx and Eurasian lynx are sister taxa. Relative to most other felid species, genetic variation in mtDNA genes and nuclear microsatellites were reduced in Iberian lynx, suggesting that they experienced a fairly severe demographic bottleneck. In addition, the effects of more recent reductions in gene flow and population size are being manifested in local patterns of molecular genetic variation. These data, combined with recent studies modeling the viability of Iberian lynx populations, should provide greater urgency for the development and implementation of rational in situ and ex situ conservation plans.

Animals↗

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Genetic and morphological divergence among sympatric canids.

Numerous studies have suggested that the extent of character divergence observed between two sympatric species reflects the intensity of competition for resources or space. However, the influence of time on divergence is often overlooked. We examined the relationship between time and character divergence in two groups of congeneric, sympatric canids on two continents: South American foxes and African jackals. Character divergence was assessed from measurements of body mass and dental and cranial shape. Divergence time was estimated from data on mitochondrial DNA restriction site polymorphisms. Our findings indicate that African jackals are morphologically similar despite having diverged more than 2 million years ago. By contrast, South American foxes differ substantially in both size and morphology after only 250,000 years of evolution. Thus, the lack of character divergence among the African jackals cannot be explained as a result of very recent common ancestry.

Animals↗

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The costs of caring for the elderly--a panel discussion.

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Age Factors↗