Reptiles and mammals have differentially retained long conserved noncoding sequences from the amniote ancestor.

Many noncoding regions of genomes appear to be essential to genome function. Conservation of large numbers of noncoding sequences has been reported repeatedly among mammals but not thus far among birds and reptiles. By searching genomes of chicken (Gallus gallus), zebra finch (Taeniopygia guttata), and green anole (Anolis carolinensis), we quantified the conservation among birds and reptiles and across amniotes of long, conserved noncoding sequences (LCNS), which we define as sequences ≥500 bp in length and exhibiting ≥95% similarity between species. We found 4,294 LCNS shared between chicken and zebra finch and 574 LCNS shared by the two birds and Anolis. The percent of genomes comprised by LCNS in the two birds (0.0024%) is notably higher than the percent in mammals (<0.0003% to <0.001%), differences that we show may be explained in part by differences in genome-wide substitution rates. We reconstruct a large number of LCNS for the amniote ancestor (ca. 8,630) and hypothesize differential loss and substantial turnover of these sites in descendent lineages. By contrast, we estimated a small role for recruitment of LCNS via acquisition of novel functions over time. Across amniotes, LCNS are significantly enriched with transcription factor binding sites for many developmental genes, and 2.9% of LCNS shared between the two birds show evidence of expression in brain expressed sequence tag databases. These results show that the rate of retention of LCNS from the amniote ancestor differs between mammals and Reptilia (including birds) and that this may reflect differing roles and constraints in gene regulation.

Paleogenomic data suggest mammal-like genome size in the ancestral amniote and derived large genome size in amphibians.

An unsolved question in evolutionary genomics is whether amniote genomes have been expanding or contracting since the common ancestor of this diverse group. Here, we report on the polarity of amniote genome size evolution using genome size estimates for 14 extinct tetrapod genera from the Paleozoic and early Mesozoic Eras using osteocyte lacunae size as a correlate. We find substantial support for a phylogenetically controlled regression model relating genome size to osteocyte lacunae size (P of slopes <0.01, r²=0.65, phylogenetic signal λ=0.83). Genome size appears to have been homogeneous across Paleozoic crown-tetrapod lineages (average haploid genome size 2.9-3.7 pg) with values similar to those of extant mammals. The differentiation in genome size and underlying architecture among extant tetrapod lineages likely evolved in the Mesozoic and Cenozoic Eras, with expansion in amphibians, contractions along the diapsid lineage, and no directional change within the synapsid lineage leading to mammals.

Wing pointedness associated with migratory distance in common-garden and comparative studies of stonechats (Saxicola torquata).

Migration promotes utilization of seasonal resources, and the distance flown is associated with specific morphologies, yet these relationships can be confounded by environmental factors and phylogeny. Understanding adaptations associated with migration is important: although migration patterns change rapidly, it is unclear whether migratory traits track behavioural shifts. We studied morphometrics of four stonechat populations representing a migratory gradient and raised under common-garden conditions. With multivariate analyses, we identified wing traits that differed clearly from general size trends, and used phylogenetic comparative methods to test the prediction that these traits correlated with migratory distance in captive and wild populations. Pointedness differed among populations, changed independently from overall body size, and was correlated with migration distance. Migration in stonechats may lead to deviations from allometric size changes, suggesting that birds may adapt morphologically to selection pressures created by their own behaviour in response to changing environmental conditions.

Interleukin-1 and interleukin-8 in nicotine- and lipopolysaccharide-exposed gingival keratinocyte cultures.

BACKGROUND AND OBJECTIVE: Tobacco use is associated with increased periodontal destruction in both cigarette smokers and smokeless tobacco users. Gingival keratinocytes are the first cells in contact with microbial and tobacco components and play a key role in the innate immune response to these agents. The objective of this study was to evaluate the effect of nicotine and bacterial lipopolysaccharide (LPS) alone and in combination on gingival keratinocyte production of interleukin-1 alpha (IL-1 alpha) and interleukin-8 (IL-8). MATERIAL AND METHODS: Gingival keratinocyte cultures were established from 10 healthy, non-tobacco-using subjects. The cells were stimulated for 24 h with 1 mum or 1 mm nicotine and/or 10 microg/mL Escherichia coli or Porphyromonas gingivalis LPS. Interleukin-1 alpha and IL-8 proteins were quantified using ELISAs. RESULTS: Compared with untreated cultures, 1 mm nicotine stimulated production of IL-1 alpha (p < 0.001); E. coli and P. gingivalis LPS increased IL-8 production (p = 0.0014 and p = 0.0232, respectively). A combination of nicotine and LPS produced the highest cytokine quantities. Amounts of IL-1 alpha and IL-8 following 1 mm nicotine and LPS exposure were significantly greater than in untreated cultures (p < 0.001). Interleukin-8 was also responsive to 0.1 mum nicotine combined with E. coli or P. gingivalis LPS compared with control cultures (p < 0.0001 and p = 0.0029, respectively). Both cytokines tended to be elevated following the combined treatment relative to nicotine or LPS treatment alone. CONCLUSION: These results demonstrate that nicotine and LPS differentially regulate IL-1 and IL-8 production by gingival keratinocytes. Combined treatment tended to elevate cytokine production further, which may have implications for the progression of periodontitis in tobacco users.

Variability in sex-determining mechanisms influences genome complexity in reptilia.

In this review, we describe the history of amniote sex determination as a classic example of Darwinian evolution. We suggest that evolutionary changes in sex determination provide a foundation for understanding important aspects of chromosome and genome organization that otherwise appear haphazard in their origins and contents. Species with genotypic sex determination often possess heteromorphic sex chromosomes, whereas species with environmental sex determination lack them. Through a series of mutations followed by selection at key genes, sex-determining mechanisms have turned over many times throughout the amniote lineage. As a consequence, amniote genomes have undergone gains or losses of sex chromosomes. We review the genomic and ecological contexts in which either temperature-dependent or genotypic sex determination has evolved. Once genotypic sex determination emerges in a lineage, viviparity and heteromorphic sex chromosomes become more likely to evolve. For example, in extinct marine reptiles, genotypic sex determination apparently led to viviparity, which in turn facilitated their pelagic radiation. Sex chromosomes comprise genome regions that differ from autosomes in recombination rate, mutation rate, levels of polymorphism, and the presence of sex-determining and sexually antagonistic genes. In short, many aspects of amniote genome complexity, life history, and adaptive radiation appear contingent on evolutionary changes in sex-determining mechanisms.

A history of the dissolution of retained choledocholithiasis.

BACKGROUND: Common duct calculi retained after gallbladder surgery continue to present a clinical challenge especially in the era of minimally invasive surgery. This review examines the strategy of dissolution therapy used throughout the history of biliary tract surgery and its use to the modern surgeon. DATA SOURCES: Original journal articles and reviews were identified using standard surgical textbooks and MEDLINE. Keywords for searching included choledocholithiasis, dissolution, mono-octanoin, common duct stones, MTBE, cholic acid, and gallstones. CONCLUSIONS: Dissolution therapy used initially as an alternative to open surgery is now used more effectively as an adjunct to laparoscopic or endoscopic biliary tract surgery. The current review demonstrates a majority of patients with retained choledocholithiasis respond to dissolution and can be safely managed without choledochotomy.

Thyroid gland and surgery of the thyroglossal duct: exercise in applied embryology.

Thyroglossal duct cysts (TDCs), the most common congenital cervical abnormality, originates from the medial anlage of the thyroid gland and presents as a painless asymptomatic midline suprahyoid mass. It does not represent a diagnostic challenge. The tract may persist as a fibrous cord or leave nests of cells anywhere along its embryonic path, and it gives rise to the development of TDC. The Sistrunk operation described in 1920 consists of en bloc cystectomy and central hyoidectomy, with tract excision up to the foramen cecum. This procedure remains an effective treatment for TDC. Malignant degeneration of TDC is rare (0.7%).

Changing patterns of resident operative experience from 1990 to 1997.

HYPOTHESIS: Resident operative experience has increased or decreased with respect to 12 specific operations. DESIGN: A retrospective analysis of resident operative experience reported to the Accreditation Committee for Graduate Medical Education for academic years 1990-1997. SUBJECTS: Residents completing an Accreditation Committee for Graduate Medical Education surgical program. MAIN OUTCOME MEASURES: The total number of residents, average number of operations performed per resident, and the most common operations performed. RESULTS: The number of house staff completing surgical residency training programs has remained constant, while operative volume has increased from 1991 to 1997. Comparison of the frequencies of 12 selected operative procedures performed in academic years 1990-1991 and 1996-1997 found increases in the following procedures: carotid endarterectomy (137%), pancreaticoduodenectomy (66.7%), laparoscopic cholecystectomy (64.8%), parathyroidectomy (51.2%), thyroidectomy (19.2%), colectomy (14.1% to 44.4% depending on subtype), and elective infrarenal aortic aneurysm repair (10.7%). Conversely, frequencies decreased for open cholecystectomy (63.4%), open parietal cell vagotomy (40%), modified radical mastectomy (15.2%), gastroesophageal antireflux procedure (10.4%), and subtotal gastric resection (8.93%). Resident experience was essentially unchanged for emergent infrarenal aortic aneurysm repair and laparoscopic proximal gastric vagotomy. CONCLUSIONS: The number and variety of operative interventions in surgical therapeutics is changing. Continued analysis of the operative experience during surgical training will indicate the need for changing requirements for surgical resident experience. The causes of these shifts are not specifically addressed by this study. Perhaps technological advances in the diagnosis and management of surgical patients or the increase in subspecialty training programs have affected the experience of general surgery trainees.

Ethics in surgery: historical perspective.

Ethics codes and guidelines date back to the origins of medicine in virtually all civilizations. Developed by the medical practitioners of each era and culture, oaths, prayers, and codes bound new physicians to the profession through agreement with the principles of conduct toward patients, colleagues, and society. Although less famous than the Hippocratic oath, the medical fraternities of ancient India, seventh-century China, and early Hebrew society each had medical oaths or codes that medical apprentices swore to on professional initiation. The Hippocratic oath, which graduating medical students swear to at more than 60% of US medical schools, is perhaps the most enduring medical oath of Western civilization. Other oaths commonly sworn to by new physicians include the Declaration of Geneva (a secular, updated form of the Hippocratic oath formulated by the World Medical Association, Ferney-Voltaire, France) and the Prayer of Moses Maimondes, developed by the 18th-century Jewish physician Marcus Herz.