Highly divergent sympatric lineages of Leptotila verreauxi(Aves:Columbidae)suggest a secondary contact area in the Isthmus of Tehuantepec,Mexico

Due to a complex geological and biotic history,the Isthmus of Tehuantepec(IT),has been long recognized as a driver for the evolutionary divergence of numerous lowland and highland taxa.Widely distributed in the lowlands of the American continent,the White-Tipped Dove(Leptotila verreauxi)is a polytypic species with 13 recognized subspecies.Four of these have been recorded in Mexico,and the distribution of three abuts at the IT,suggesting a contact zone.To estimate phylogenetic patterns,divergence times and genetic differentiation,we examined two mt DNA(ND2 and COI)and one n DNA(β-fibint 7)markers.We also used correlative ecological niche models(ENM)to assess whether ecological differences across the IT may have acted as a biogeographical boundary.We estimated paleodistributions during the Middle Holocene,Last Glacial Maximum and Last Interglacial,to evaluate the influence of climate changes on the distribution and demographic changes.Our results showed genetically distinct lineages that diverged approximately 2.5 million years ago.Climatic and ecological factors may have played a dual role in promoting differentiation,but also in the formation of a secondary contact zone in the southern IT.Our ecological niche comparisons indicated that the ecological niche of sympatric lineages at the IT are not identical,suggesting niches divergence;in addition,environmental niche models across the region indicated no abrupt biogeographic barriers,but the presence of regions with low suitability.These results suggest that genetic differentiation originated by a vicariant event probably related to environmental factors,favored the evolution of different ecological niches.Also,the absence of a biogeographic barrier but the presence of less suitable areas in the contact regions,suggest that secondary contact zones may be also maintained by climatic factors for the eastern group,but also by biotic interactions for the western group.

Phylogenetic Patterns of the Southeast Asian Tree Frog Chiromantis hansenae in Thailand

Although landscape features such as mountains and rivers are recognized often as limiting factors to amphibian dispersal and gene flow, a limited number of studies have investigated such patterns across Southeast Asia. A perfect example of this is Thailand, located in one of the world＇s biodiversity hotspot regions. Thailand represents the corridor between mainland Asia and the Sunda Shelf, a famous and widely recognized biogeographic region, and yet there are few studies on the genetic structure among populations of amphibian species distributed across Thailand. The Southeast Asian tree frog, Chiromantis hansenae has been reported to possess a geographic range that is restricted to Thailand and, presumably, Cambodia~ Here, we investigate phylogenetic relationships among C. hansenae populations using partial sequences of the mitochondrial 16S rRNA gene and nuclear POMC gene. Our results reveal two distinct evolutionary lineages within C. hansenae populations in Thailand. The genetic divergence among populations between these two clades is considerable, and results support inter-population divergence, and high genetic differentiation （pairwise FsT = 0.97）, between two localities sampled in western Thailand （TK1 and TK2）, separated from each other by 40 kilometers only. The results suggest that landscape features across Thailand may have a profound impact on patterns of diversification in the country, underscoring the urgent need for fine-scale investigations of genetic structure of endemic and ＂widespread＂ species.

Treatment Outcome of Papillary Carcinoma Confined to the Thyroid Isthmus

Objective: The purpose of this study is to evaluate the clinicopathologic characteristics and treatment outcomes of Papillary Thyroid Carcinomas (PTC) of the isthmus and to establish an appropriate surgical strategy. Methods: Thirty-four patients with PTC in isthmus are managed by surgery in National Cancer Center/Cancer Hospital of Chinese Academy of Medical Sciences, Peking Union Medical College from 1985-2008. Demographic data, surgical procedures, pathological features, stages and outcomes are analyzed. Results: Seven patients were men and 27 were women. The median age was 41 years (range, 20 - 71). Twenty-five patients were treated with thyroid isthmusectomy or wide field isthmusectomy, five with hemithyroidectomy (lobectomy and isthmusectomy) and four with hemithyroidectomy and partial resection of the contralateral lobe. Twenty-eight patients had a pathologically T1 lesion (pT1);two patients had a pT2 lesion and four had a pT3 lesion. Five patients (14.7%) had papillary carcinoma detected in one of the pretracheal lymph nodes. Thirty-two patients had a solitary lesion confined to the thyroid isthmus. One patient had two lesions in the thyroid isthmus and another one had two lesions located in the thyroid isthmus and right lobe respectively. With a median follow-up of 94 months (range, 12 - 274), two patients had a recurrence and both survived after a re-operation. There was no regional lymph node or distant organ recurrences. No deaths occurred. Conclusions: Isthmusectomy or wide field isthmusectomy could be a sufficient treatment for PTC confined to the thyroid isthmus. We also recommend that pretracheal lymph node dissection be considered.

The sperm-interacting proteome in the bovine isthmus and ampulla during the periovulatory period

Background Spermatozoa interact with oviduct secretions before fertilization in vivo but the molecular players of this dialog and underlying dynamics remain largely unknown.Our objectives were to identify an exhaustive list of sperm-interacting proteins(SIPs)in the bovine oviduct fluid and to evaluate the impact of the oviduct anatomical region(isthmus vs.ampulla)and time relative to ovulation(pre-ovulatory vs.post-ovulatory)on SIPs number and abundance.Methods Pools of oviduct fluid(OF)from the pre-ovulatory ampulla,pre-ovulatory isthmus,post-ovulatory ampulla,and post-ovulatory isthmus in the side of ovulation were collected from the slaughterhouse.Frozen-thawed bull sperm were incubated with OF or phosphate-buffered saline(control)for 60 min at 38.5℃.After protein extraction and digestion,sperm and OF samples were analyzed by nanoLC-MS/MS and label-free protein quantification.Results A quantitative comparison between proteins identified in sperm and OF samples(2333 and 2471 proteins,respectively)allowed for the identification of 245 SIPs.The highest number(187)were found in the pre-ovulatory isthmus,i.e.,time and place of the sperm reservoir.In total,41 SIPs(17%)were differentially abundant between stages in a given region or between regions at a given stage and 76 SIPs(31%)were identified in only one region×stage condition.Functional analysis of SIPs predicted roles in cell response to stress,regulation of cell motility,fertilization,and early embryo development.Conclusion This study provides a comprehensive list of SIPs in the bovine oviduct and evidences dynamic spatiotemporal changes in sperm-oviduct interactions around ovulation time.Moreover,these data provide protein candidates to improve sperm conservation and in vitro fertilization media.

Real-time cardiovascular magnetic resonance-guided radiofrequency ablation:A comprehensive review

Cardiac magnetic resonance(CMR)imaging could enable major advantages when guiding in real-time cardiac electrophysiology procedures offering high-resolu-tion anatomy,arrhythmia substrate,and ablation lesion visualization in the absence of ionizing radiation.Over the last decade,technologies and platforms for performing electrophysiology procedures in a CMR environment have been developed.However,performing procedures outside the conventional fluoro-scopic laboratory posed technical,practical and safety concerns.The development of magnetic resonance imaging compatible ablation systems,the recording of high-quality electrograms despite significant electromagnetic interference and reliable methods for catheter visualization and lesion assessment are the main limiting factors.The first human reports,in order to establish a procedural workflow,have rationally focused on the relatively simple typical atrial flutter ablation and have shown that CMR-guided cavotricuspid isthmus ablation represents a valid alternative to conventional ablation.Potential expansion to other more complex arrhythmias,especially ventricular tachycardia and atrial fibrillation,would be of essential impact,taking into consideration the widespread use of substrate-based strategies.Importantly,all limitations need to be solved before application of CMR-guided ablation in a broad clinical setting.

Mitral isthmus ablation in patients with prosthetic mitral valves

Background Previous studies have investigated the technique of linear ablation at the mitral isthmus （MI） in patients with idopathic atrial fibrillation （AF）, but MI ablation in patients with prosthetic natural mitral valves （MVs） was not described in detail. Present study sought to summarize our initial experience of ablating MI in patients with prosthetic MVs Methods Patients with drug refractory AF and prosthetic MVs were eligible for this study, and the patients with natural MVs but received MI ablation served as control group. Left atrium （LA） mapping and ablation was carried out guided by CARTO system. The anatomy of MI was assessed via computer topography scan. Results During the study period, a consecutive of 19 patients （male/female=12/7, mean age of （48±6） years） with prosthetic MVs （16 with metal valves, 3 with biologic valves） entered for AF ablation, other 35 patients served as control group. In study group, mapping along MI documented lower voltages （（2.0±1.0） vs. （3.1±1.3） mV, P=-0.002）, more fragmented potentials （19/19 vs. 20/15, P 〈0.001 ）, and higher impedance （（132±34） vs. （110±20） Ω, P=0.004）. After initial ablation, more residual gaps along the MI lesions were found in study group （2.4±0.4 vs. 1.7±0.3, P 〈0.001）. The mean length of MI （（6.2±3.3） vs. （7.1±2.3） cm, P=-0.25） was comparable between 2 groups, but the MI in study group was much thicker （（3.1±1.8） vs. （2.1±1.07） cm, P=0.01） and all were found as pouch type （19/19 vs. 2/35, P 〈0.001）. The follow-up results were comparable （65.1% vs. 72.3%, P=-0.30）. Conclusion For patients with prosthetic MVs, linear ablation at MI could be successfully carried out despite anatomical and pathological changes.

SENSITIVITY OF AVIAN MESENCEPHALIC NEURONS TO AMINO ACIDS

It has been shown that in the avian optic tectum, L-glutamate may be an excitatory transmitter, whereas glycine and γ-aminobutyric acid (GABA) may be inhibitory transmitters. Tritiated glycine injections in the avian tectum label the cell bodies within the nucleus isthmus pars parvocellularis (Ipc). Electrical stimulation of Ipc results in the release of exogenous and endogenous glycine into tectal perfusate. It is, therefore, suggested that the isthmotectal pathway uses glycine as its transmitter. Tectal injections of of tritiated GABA also label Ipc cell bodies, indicating that the isthmotectal projection contains GABAergic fibers.

Evaluation of transisthmus conduction interval in predicting bidirectional block after ablation of typical atrial flutter

Objective To determine whether the extent of prolongation of the transisthmus interval after ablation predicts complete bidirectional block.Methods Since 1996 to 2002, 30 consecutive patients underwent ablation procedures for isthmus-dependent atrial flutter. There were 23 males and 7 females [ mean age (47. 85 ±9. 35) years]. With the use of fluoroscopic view of anatomy, radiofrequency ablation was performed during coronary sinus pacing at a cycle length of 600 ms.Results Bidirectional block was achieved with ablation in 29 (97%) of 30 patients. The transisthmus intervals before ablation and after complete transisthmus block were (73.82±13. 01 ) ms and (140. 47±20. 48) ms, respectively, in the clockwise direction (P<0. 0001), and (77. 63±8. 36) ms and (138. 17 ±15. 55) ms, respectively, in the counterclockwise direction (P<0. 0001). A period of incomplete isthmus block was observed during 17 (58%) of the 29 ablation procedures. The clockwise transisthmus intervals during incomplete block [(107. 65 ±21. 33) ms] were (45.5 ± 8. 7)% longer than the baseline transisthmus intervals. An increase in the transisthmus interval by ≥50% in both directions after ablation predicted complete bidirectional block with 100.0% sensitivity and 83. 3% specificity. The positive and negative predictive values were 90. 6% and 100.0% , repectively. The diagnostic accuracy of a≥50% prolongation in the transisthmus interval was 83. 3%.Conclusion The analysis of transisthmus interval is a valuable method for determining complete bidirectional isthmus block.