Molecular systematics and historical biogeography of tree boas (Corallus spp.).

Inferring the evolutionary and biogeographic history of taxa occurring in a particular region is one way to determine the processes by which the biodiversity of that region originated. Tree boas of the genus Corallus are an ancient clade and occur throughout Central and South America and the Lesser Antilles, making it an excellent group for investigating Neotropical biogeography. Using sequenced portions of two mitochondrial and three nuclear loci for individuals of all recognized species of Corallus, we infer phylogenetic relationships, present the first molecular analysis of the phylogenetic placement of the enigmatic C. cropanii, develop a time-calibrated phylogeny, and explore the biogeographic history of the genus. We found that Corallus diversified within mainland South America, via over-water dispersals to the Lesser Antilles and Central America, and via the traditionally recognized Panamanian land bridge. Divergence time estimates reject the South American Caribbean-Track as a general biogeographic model for Corallus and implicate a role for events during the Oligocene and Miocene in diversification such as marine incursions and the uplift of the Andes. Our findings also suggest that recognition of the island endemic species, C. grenadensis and C. cookii, is questionable as they are nested within the widely distributed species, C. hortulanus. Our results highlight the importance of using widespread taxa when forming and testing biogeographic hypotheses in complex regions and further illustrate the difficulty of forming broadly applicable hypotheses regarding patterns of diversification in the Neotropical region.

[F-18]-Fluorodeoxyglucose PET and PET-CT in diagnostic imaging evaluation of locally recurrent and metastatic bladder transitional cell carcinoma.

BACKGROUND: Little data is available on the utility of positron emission tomography (PET) and positron emission tomography-computed tomography (PET-CT) with [F-18]-fluorodeoxyglucose (FDG) in patients with bladder cancer. We retrospectively assessed the diagnostic utility of dedicated PET and hybrid PET-CT scans with [F-18]-FDG in the imaging evaluation of recurrent and metastatic bladder transitional cell carcinoma. METHODS: The study group included 35 patients who were previously treated for the primary disease. We performed PET in 17 patients and 23 PET-CT scans in 18 patients. Diagnostic validation was by biopsy in 1 patient and clinical and radiological follow-up for up to 5 years in the remaining patients. RESULTS: PET and CT were true negative (TN) in 12 patients and true positive (TP) in 19 patients. In 4 patients in this group, both locally recurrent pelvic mass and distant metastases were demonstrated, while in 3 of these patients, unsuspected skeletal and/or nodal metastases were detected by PET-CT and these patients received additional courses of chemotherapy. PET was discordant with CT in 4 patients. PET was negative in 2 of these patients, while post-chemotherapy CT showed enlarged nodes that were determined to represent successfully treated disease. In another patient, a hypometabolic soft-tissue mass was considered to represent a scar, and a wait-and-watch strategy was pursued. In the remaining patient, PET showed random hypermetabolic osseous lesions that represented early marrow metastatic infiltration. The combined diagnostic information provided by PET-CT affected the clinical management in 17% of patients. CONCLUSION: FDG PET and PET-CT scanning may improve the imaging evaluation of patients with recurrent and metastatic bladder cancer.

[F-18]fluorodeoxyglucose positron emission tomography and positron emission tomography: computed tomography in recurrent and metastatic cholangiocarcinoma.

OBJECTIVES: We retrospectively assessed the diagnostic utility of dedicated positron emission tomography (PET) and hybrid PET-computed tomography (CT) scans with [F-18]fluorodeoxyglucose (FDG) in the imaging evaluation of patients with known or suspected recurrent and metastatic cholangiocarcinoma. METHODS: The study group included 24 patients (13 males and 11 females; age range, 34-75 years) with known or suspected recurrent and metastatic cholangiocarcinoma. We performed 8 dedicated PET scans (Siemens 953/A, Knoxville, Tenn) in 8 patients and 24 hybrid PET-CT scans (Siemens Biograph, Knoxville, Tenn) in 16 patients. Four patients underwent both pretreatment and posttreatment scans. Nonenhanced CT transmission scans were obtained for attenuation correction after administration of oral contrast material. PET images were obtained 60 minutes after the intravenous administration of 15 mCi (555 MBq) FDG. Prior treatments included surgery alone in 12 patients, surgery and chemotherapy in 6 patients, and surgery and combined chemoradiation therapy in 6 patients. Diagnostic validation was conducted through clinical and radiologic follow-up (2 months to 8 years). RESULTS: PET and CT were concordant in 18 patients. PET-CT correctly localized a hypermetabolic metastatic lesion in the anterior subdiaphragmatic fat instead of within the liver and was falsely negative in intrahepatic infiltrating type cholangiocarcinoma. PET was discordant with CT in 6 patients. PET was negative in an enlarged right cardiophrenic lymph node on CT, which remained stable for 1 year. In 1 patient, PET-CT scan showed hypermetabolic peritoneal disease in the right paracolic gutter without definite corresponding structural abnormalities, which was subsequently confirmed on a follow-up PET-CT scan performed 6 months after the initial study, at which time peritoneal nodular thickening was evident on concurrent CT. PET-CT documented the progression of locally recurrent and metastatic disease in another patient based on interval appearance of several new hypermetabolic lesions and significant increase in the standardized uptake values of the known lesions despite little interval change in the size and morphologic character of lesions on concurrent CT. It was also helpful in excluding metabolically active disease in patients with contrast enhancement at either surgical margin of hepatic resection site or focally within hepatic parenchyma and in an osseous lesion. Overall, based on the clinically relevant patient basis for detection of recurrent and metastatic cholangiocarcinoma, the sensitivity and specificity of PET (alone and combined with CT) were 94% and 100% and, for CT alone, were 82% and 43%, respectively. CONCLUSIONS: FDG PET and PET-CT are useful in the imaging evaluation of patients with cholangiocarcinoma (except for infiltrating type) for detection of recurrent and metastatic disease and for assessment of treatment response. In particular, the combined structural and metabolic information of PET-CT enhances the diagnostic confidence in lesion characterization.

2-deoxy-2-[F-18]fluoro-D-glucose-positron emission tomography/computed tomography imaging evaluation of esophageal cancer.

We evaluated the clinical utility of 2-deoxy-2-[F-18]fluoro-D-glucose (FDG)-positron emission tomography (PET)/computed tomography (CT) on the precise localization of pathologic foci and exclusion of normal variants in the imaging evaluation of patients with esophageal carcinoma. Combined PET/CT scans were performed in 60 patients (50 males, 10 females, age range 47-84 years) with history of esophageal carcinoma either at the time of initial diagnosis (group I, n=14) or for surveillance and/or detection of recurrent and metastatic disease (group II, n=46). Prior treatments included esophagectomy with gastric pull-up (n=23), surgery and chemotherapy (n=3), surgery and chemoradiation therapy (n=10), chemotherapy alone (n=5), radiation therapy alone (n=2), and chemoradiation without surgery (n=3). Diagnostic validation was by tissue sampling in three patients and clinical/radiological follow-up for up to 1.5 years in the remaining patients. In group I, discordant abnormalities were noted in seven patients. PET demonstrated hypermetabolism in normal-size lymph nodes on CT in three patients that were considered likely true positive in view of concurrent existence of other adjacent enlarged hypermetabolic lymph nodes in the same nodal basin. Hypometabolic incidental CT abnormalities of up to 1-cm lung nodules were noted in three patients and pleural effusion in one patient, which were considered true negative in view of no change on follow-up PET/CT studies. In group II, both PET and CT showed concordant abnormalities in 23 patients. The precise image fusion of hypermetabolism in a liver lesion allowed a diagnostic CT-guided biopsy in one patient. PET demonstrated true positive hypermetabolic abnormalities in four patients that localized to structures, which were normal by noncontrast CT criteria, and true negative in one patient with hepatic fatty deposits. PET showed decline in metabolic activity of the primary lesion in one patient after chemotherapy, while the corresponding CT abnormality remained unchanged. PET/CT image fusion provided relevant complementary diagnostic information in 14 patients with discordant findings (23% of total) that resulted in biopsy in three cases, institution of chemotherapy in four cases, and a wait-and-watch strategy in seven cases. In conclusion, our findings add to the current body of literature that suggests that FDG-PET/CT scanning may improve the imaging evaluation of patients with esophageal cancer by providing complementary structural-metabolic information. In particular, our findings support the notion that PET/CT may be the most appropriate imaging modality in the evaluation of patients of esophageal cancer that may impact patient management.

The diets of Hispaniolan colubrid snakes : I. Introduction and prey genera.

Approximately 1590 Hispaniolan colubrid snakes representing six genera and eight species were examined for prey remains (Alsophis cantherigerus, Antillophis parvifrons, Darlingtonia haetiana, Hypsirhynchus ferox, Ialtris dorsalis, Uromacer catesbyi, U. frenatus, and U. oxyrhynchus). The snakes were collected at many localities over a span of 80 years.Of 426 prey items, 77.9% were lizards (of which 69.6% were anoles), 19% frogs, 2.6% birds and mammals, and 0.5% other snakes. Darlingtonia was the only snake that did not exploit lizards; it fed exclusively on Eleutherodactylus frogs, including egg clutches. Disregarding Darlingtonia, there is no size class of Hispaniolan colubrids between 20-90 cm SVL that does not prey primarily on Anolis. Certain prey genera are added to, or deleted from, diets depending on snake size, but the data suggest that snake SVL alone does little to dictate what prey genera (or groups) are eaten. Shannon-Wiener values (H') indicate that Darlingtonia has the narrowest trophic niche, while Alsophis and Ialtris have the widest. Values of H' are not correlated with snake SVL, but highly significant (P<0.001) correlations exist between H' and mid-body circumference, head width, and snout width, and these characters may be indicators of trophic generalists and specialists. Anolis lizards are the most ubiquitous and conspicuous vertebrates on Hispaniola, and it is not surprising that they are widely exploited as a food source. Although as some snake species grow larger, anoles play a decreasingly important role in their diets, there is no evidence to suggest that they are ever abandoned as a food source by any Hispaniolan colubrid of any size.Secretive lizards of low vagility are eaten almost exclusively by wide ranging foragers (Alsophis, Antillophis); very active prey (Ameiva) is taken by sit-and-wait strategists (Hysirhynchus, U. frenatus). Those snakes which exploit the most prey groups are active foragers. Uromacer catesbyi exhibits both foraging modes, and predictably, eats diurnally active (anoles) and diurnally quiescent (hylid frogs) prey with almost equal frequency.Within Maglio's cantherigerus species assemblage, in which an Alsophis cantherigerus-like snake was ancestral to the other species, and in which longsnouted Uromacer are the most morphologically derived, there is an obvious trend toward trophic specialization on Hispaniola. The West Indies have provided an ideal natural laboratory for the investigation of many aspects of vertebrate ecology, and an arena in which to test theories of island biogeography. The most extensively studied West Indian vertebrates have been the lizards of the iguanid genus Anolis. Conversely, the ecology of West Indian snakes has been largely ignored. This is surprising in light of the fact that much has been written about Anolis predation, but little has been written about predators of Anolis; snakes may be important, frequent consumers of anoles.Hispaniola is physiographically and ecologically the most diverse of the Greater Antilles and, concomitantly, it has the most diverse snake fauna, including six colubrid genera containing 11 described species. It has rich frog and lizard faunas, but only two endemic mammals. Study of the diets of Hispaniola's colubrid snakes was undertaken to gain initial insights into the ecology of the snakes and to determine 1) what the snakes eat; 2) what relationships exist between snake diet and snake size as well as head and body proportions; 3) what relationships exist between snake foraging mode and prey type and size; 4) if anoles, as the most ubiquitous and conspicuous vertebrates on Hispaniola, comprise an important source of food; 5) if significant geographical differences in diet exist, expecially on satellite islands; 6) if "north island" and "south island" (sensu Williams 1961) Anolis ecomorphs are preyed upon by the same snake species in similar proportions; 7) if snakes are selective or opportunistic predators.This paper, the first in a series that will address all of the above topics, will briefly describe methods, snake species and prey genera. Prey genera are analyzed in terms of what snake taxa prey upon them, what size classes of snakes prey upon them, and prey genera diversity versus snake size and proportions.