Segment A2 Research Articles

Variantes anatómicas del círculo arterial cerebral en un anfiteatro universitario en Bogotá (Colombia)

Introducción: el cerebro es un órgano altamente irrigado, y esta irrigación es suministrada por el círculo arterial cerebral: una red arterial anastomótica con frecuentes variaciones anatómicas, algunas asociadas con patologías. El objetivo es describir las características antropométricas y variaciones anatómicas del círculo arterial cerebral en una muestra de especímenes cadavéricos humanos. Materiales y métodos: se revisaron 50 encéfalos, de los cuales 24 cumplieron con los criterios de inclusión. Se realizaron medidas de diámetro y longitud y también se describieron variaciones anatómicas y variaciones morfométricas. Resultados: siete especímenes evidenciaron variaciones anatómicas (29.1%); 3 (12.5%), arteria cerebral anterior (ACA) ácigos; uno (4.1%), doble ACA en el segmento A1; uno (4.1%), triple ACA en el segmento A2 y doble arteria comunicante anterior (AcomA); uno (4.1%), agenesia de la arteria comunicante posterior (AComP) derecha; uno (4.1%), de la AComP izquierda. El 29.1% presentó variaciones antropométricas; el 12.5 %, hipoplasia de la AComP derecha; el 12.5 %, de la AComP izquierda, y el 4.1 %, hipoplasia bilateral de la AComP. Conclusión: la presencia de variaciones anatómicas fue inferior a la hallada en otros estudios, con predominio de variantes de la circulación anterior. Se describe la presencia de triple aca en el segmento A2 y doble arteria comunicante anterior.

PTB7-Th based organic solar cell with a high Voc of 1.05 V by modulating the LUMO energy level of benzotriazole-containing non-fullerene acceptor

The open-circuit voltage (Voc) of classical photovoltaic polymers, such as P3HT and PTB7-Th, are always restricted when combining with fullerene derivatives, due to the difficulty of modulating the energy levels of fullerene derivatives. Thus, design of new non-fullerene small molecule acceptor (NFSMA) is very significant to match with these mature polymer donors and improve the Voc and power conversion efficiency (PCE). Here, a new benzotriazole (BTA)-based NFSMA, BTA7 was synthesized by adopting A2A1DA1A2 type molecular backbone. By using a strong electron-accepting unit of malononitrile (M) as terminal segment A2, BTA7 demonstrates strong crystallinity, red-shifted absorption spectrum and down-shifted lowest unoccupied molecular orbital (LUMO) energy levels in comparison with BTA1 and BTA2. Organic solar cells (OSCs) based on PTB7-Th:BTA7 realized a high Voc of 1.05V with a moderate PCE of 4.60%. The energy loss (Eloss=Eg−eVoc) of 0.53eV is lower than the experiential minimum value of 0.6eV, which indicates PTB7-Th still has large potential to improve the Voc and photovoltaic performance after the development of novel electron acceptors.

Integrated hydroacoustic flares and geomechanical characterization reveal potential hydrocarbon leakage pathways in the Perth Basin, Australia

Geoscience Australia (GA) and the Commonwealth Scientific and Industrial Research Organisation (CSIRO) conducted a marine survey including monitoring hydroacoustic flares in order to understand the natural leakage pathways in the offshore northern Perth Basin. 186 hydroacoustic contacts were encountered and classified and thirty two were interpreted as possible seeps or expulsion of gases from the subsurface. The contacts were typically distributed above areas of interpreted subsurface faulting. In the survey site Da (15 km2), nine probable seeps and sixteen other contacts were interpreted and are aligned with a fault segment (A2) interpreted on 2D seismic reflection data. The segment A2 is part of a major N–NNW trending fault system intersecting the sedimentary sequence from the near seabed to the Permian units, including the Kockatea Shale source rock located in the oil window. Evaluation of the stress state on the fault segment A2 suggests that it is not critically stressed and therefore not likely prone to reactivation and dilation and vertical leakage under the modelled stress field. We propose that fault segment A2 acts as a baffle delimiting a migration pathway in the wall rock and permitting hydrocarbons generated from the source rock to overcome capillary entry pressures of the overlying marginal seals. The interpreted seeps could therefore be associated with intraformational vertical migration in the wall rock focused by the faults.

Quantification of Mitral Valve Anatomy by Three-Dimensional Transesophageal Echocardiography in Mitral Valve Prolapse Predicts Surgical Anatomy and the Complexity of Mitral Valve Repair

Three-dimensional (3D) transesophageal echocardiography (TEE) is more accurate than two-dimensional (2D) TEE in the qualitative assessment of mitral valve (MV) prolapse (MVP). However, the accuracy of 3D TEE in quantifying MV anatomy is less well studied, and its clinical relevance for MV repair is unknown. The number of prolapsed segments, leaflet heights, and annular dimensions were assessed using 2D and 3D TEE and compared with surgical measurements in 50 patients (mean age, 61 ± 11 years) who underwent MV repair for mainly advanced MVP. Three-dimensional TEE was more accurate (92%-100%) than 2D TEE (80%-96%) in identifying prolapsed segments. Three-dimensional TEE and intraoperative measurements of leaflet height did not differ significantly, while 2D TEE significantly overestimated the height of the posterior segment P1 and the anterior segment A2. Three-dimensional TEE quantitative MV measurements were related to surgical technique: patients with more complex MVP (one vs two to four vs five or more prolapsed segments) showed progressive enlargement of annular anteroposterior (31 ± 5 vs 34 ± 4 vs 37 ± 6 mm, respectively, P = .02) and commissural diameters (40 ± 6 vs 44 ± 5 vs 50 ± 10 mm, respectively, P = .04) and needed increasingly complex MV repair with larger annuloplasty bands (60 ± 13 vs 67 ± 9 vs 72 ± 10 mm, P = .02) and more neochordae (7 ± 3 vs 12 ± 5 vs 26 ± 6, P < .01). Measurements of MV anatomy on 3D TEE are accurate compared with surgical measurements. Quantitative MV characteristics, as assessed by 3D TEE, determined the complexity of MV repair.

Bypass graft in the management of the giant serpentine aneurysms

Objective The purpose of this study was to use graft bypass for giant serpentine aneurysms. Method 21 patients with giant serpentine aneurysms were treated with the use of graft bypass. Out of 14 patients with unruptured aneurysms, 4 patients presented with headache, 3 with reversible ischemic neurologic deficit( RIND), 5 patients had neck stiffness and features of lower cranial nerve palsy and out of the remaining two each had epilepsy and visual fields deficits respectively. 7 patients compromised ruptured aneurysms, inclusive of six patients with Hunt - Hess grade Ⅰ and Ⅱ1 , and one grade Ⅲ. Their suffering course ranged from 20 days to 3.5 years(mean, 7. 3 months). Cerebral angiography disclosed the M1 segment aneurysms of the middle cerebral artery in 6 patients and M2 segment in 4 patients, AI segment aneurysms of the anterior cerebral artery in 1 patients and A2 segment in 1 patient, P1 segment aneurysm of the posterior cerebral artery in 2 patients, basilar trunk in 2 patients, and the vertebral aneurysms in 5 patients. The aneurysm size in diameter from 0. 3 to 2. 5 cm(mean diameter, 1.2 cm), 13 aneurysms had length of more than 3. 0 cm and 8 patients with serpentine aneurysms had more than 5.0 cm. We used radial artery graft in 7 patients, superficial artery graft(STA) in 6 patients, occipital artery(OA) in 6 patients and greater saphenous vein ( GSV ) in remaining 2 patients. We underwent extra - intracranial bypass in 12 patients which includes external carotid artery to intracranial artery bypass in 5 cases, occipital artery to intracranial artery bypass in 4 cases and internal maxillary artery to intracranial artery bypass in 3 cases. The recipient intracranial vessel were anastomosed to the middle cerebral arteries in five patients, to the inferiopostrior cerebellar arteries in three patients, to P2 segment of the posterior cerebral arteries in three patients, and to anterioposterior cerebellar artery in one patient. The interposed grafts were performed between the arteries proximal and distal to the aneurysms in 9 patients, which includes interposition graft between M1 and M2 segment of the middle cerebral arteries(MCA) in three patients, M1 trunk of the MCA in two patients, the distal Al segment and proxmial A2 segment of the anterior cerebral arteries in two patients, and the extra - intracranial vertebral arteries in 2 patients. The aneurysms were trapped in 11 cases, the aneurysms were excised in 7 cases after isolating them, and the clip was places at the proximal end of the aneurysm in three cases with perforating arteries arising from the body of the aneurysm after performing the reverse flow bypass to the aneurysm sac securing the perforators. Results 20 patients returned to their normal life, they were free of headaches, seizure, visual acuity and visual field were improved and hemiparesis was recovered. One patient needed assist for his daily life. The postoperative angiographies demonstrated satisfactory patency of the bypass graft and elimination of the aneurysms in 19 patients though the patency of bypass graft in one patient was unidentifiable instead the patient was without neurological deficits clinically. One patient had developed postoperative hematoma in the ipsilateral sylvian fissure 2 days after the surgery. The hematoma was evacuated immediately but got neurological deficit on the contralateral lower limb with the power of grade Ⅳ. Conclusions Bypass graft should be an effective management for surgical treatment of giant serpentine aneurysms. Key words: Intracranial aneurysm; Cerebral revascularization; Vessel graft; Bypass

The influence of small-scale mantle heterogeneities on Mid-Ocean Ridge volcanism: Evidence from the southern Mid-Atlantic Ridge (7°30′S to 11°30′S) and Ascension Island

Volcanism along Mid-Ocean Ridges is known to exhibit significant isotopic and elemental variations, traditionally regarded as reflecting global scale variations in mantle depletion history and refertilization processes. The ∼ 400 km long Mid-Atlantic Ridge (MAR) between the Ascension and Bode Verde Fracture Zones (7°30′S to 11°30′S) has been sampled at high spatial resolution (c. 10 km along-axis scale) and large elemental and isotopic variations have been identified covering almost the entire compositional spectrum of MAR basalts. In this paper we employ a multi-isotope (Sr–Nd–Hf–Pb) and trace element approach in order to explore the geodynamic implications of along-ridge compositional variations and their relationship to off-axis volcanism on nearby Ascension Island, commonly regarded as plume-related. The studied portion of the MAR consists of four major segments. Isotopic data from the deeply incised northern and southern segments A1 and A4 define a trend involving a high-εHf depleted mantle endmember. This isotopic signature is inferred to result from an ancient melting event in the garnet stability field, causing high time-integrated Lu/Hf and elevated 176Hf/ 177Hf. In contrast, a low-εHf depleted mantle endmember is indicated by the compositional trend for samples from the topographically elevated central portion (segments A2 and A3). Both trends converge at a common enriched endmember with least diluted compositions represented by samples from the subaerial eruptive stage of nearby Ascension Island. Because linear co-variations between isotope compositions and the respective parent–daughter ratios cannot be explained as representing “mantle isochrons” we infer that our data reflect arrays related to physical mixing of depleted and enriched mantle domains. This implies that distinctive mantle domains at kilometer scale may survive convection processes over time spans in the order of 1–2 Ga. This finding corroborates the results of recent Os-isotope studies of abyssal peridotite which returned similar conclusions. The systematics of along-axis isotopic variations show that mantle upwelling is highly variable. A systematic decrease of the enriched isotopic signature from the central segment A3 toward the northern termination of the segment A2 suggests a northward flow of enriched mantle material. In marked contrast, the compositional variations along the marginal segments A1 and A4 are random indicating heterogeneous mixing of mantle domains at a spatial resolution of < 50 km to 10 km (along-axis scale). With regard to Ascension Island we show that the submarine volcanic stage, sampled by a 3216 m long drill hole, was fed by a distinctive enriched mantle source currently inaccessible to partial melting. We interpret this observation within the framework of recent local-scale geophysical investigations and infer an on-axis origin of the bulk of the Ascension volcanic edifice at around 5 to 6 Ma, synchronous with the surrounding oceanic crust. Off-axis partial melting of the current common enriched mantle endmember accounts for rejuvenation of volcanism on Ascension generating the volumetrically subordinate subaerial portion of the island.

Total Synthesis of Leustroducsin B

Leustroducsin B was synthesized via a convergent route based on division of the leustroducsin molecule into three segments A, B, and C. Two coupling reactions (Julia coupling reaction and Nozaki-Hiyama-Kishi (NHK) reaction) were employed for coupling of segments A and B: segment A1 for the Julia coupling reaction was prepared by a combination of Sharpless asymmetric epoxidation and an epoxide-cleavage reaction with an organoaluminum reagent, while segment A2 for the NHK reaction was synthesized from optically active alcohol that had previously been prepared by lipase-catalyzed kinetic resolution. Segment B, whose structure was modified with some functional groups, was synthesized from (R)-malic acid by a combination of Wittig reaction and Sharpless asymmetric dihydroxylation, and segment C, containing a cyclohexane moiety, was prepared by asymmetric Diels-Alder reaction. Segment B was first coupled with segment A1 via the Julia coupling reaction, but the yield was low due to unexpected epimerization. The NHK reaction of segment A2 proceeded to give the coupling product in good yield. This product was coupled with segment C via Wittig and Stille coupling reactions, and finally, phosphorylation was carried out by partial hydrolysis of a cyclic phosphate to give leustroducsin B.

Divergent abdominal bristle patterns in two distantly related drosophilids: antero-posterior variations and sexual dimorphism in a modular trait

The number of neurosensory bristles on abdominal sternites of Drosophila is a most investigated trait for quantitative genetic studies. However, the developmental pattern expressed on successive segments in both sexes has remained so far a neglected field. We explored three aspects of this general problem with an isofemale line design: comparing two distantly related species, Drosophila melanogaster and Zaprionus indianus, investigating bristle number variation along the antero-posterior axis, and analysing the sexual dimorphism. Antero-posterior variations could be analysed from segment A2 to A7 in females, and A2-A5 in males. In D. melanogaster, males and females showed parallel changes with a consistently lower number in males. In Z. indianus females the number was quite stable along the abdomen, while in males an important antero-posterior increase was found. The sexual dimorphism was further analysed by considering the female-male correlation and the female/male ratio. The results suggest that sternite bristle number is determined by several developmental genetic systems. One is acting along the antero-posterior axis and may be associated to a gradient, since the genetic correlation decreases when more distant segments are compared. Another is acting in the same way on most segments of both sexes, since the female-male genetic correlation is similar between homologous and non-homologous segments. Finally, genes with specific sex effects are acting on A7 in females of both species, and on A5 in Z. indianus males. The overall architecture of female and male abdomen seems to be constrained by the development of reproductive organs. A large difference between species suggests, however, that the sexual dimorphism of abdominal bristle number is not evolutionarily constrained.

Immature stages of Adelpha malea goyama Schaus (Lepidoptera: Nymphalidae, Limenitidinae)

The immature stages of Adelpha malea goyama Schaus are described from the Estação Ecol6gica do Caiuá, Paraná State, Brazil. The species uses the native liana Arrabidaea mutabilis Bur. & K. Schum. (Bignoniaceae) as larval hostplant in the study site. Isolated eggs are laid on leaf tips, and are similar in shape to those described for other species of Adelpha Hübner. Larvae pass through five stadia during 21 days, and first to third instars construct frass chains. Later instars rest on the upper leaf surface, and their body is covered by rigid branched scoli. The general profile of the pupa is elongated, with short head horns projecting laterally and with segment A2 projecting and curved anteriorly. Comparisons with closely related species of Adelpha are not conclusive, and more species in the genus need to be reared before a clear pattern of the variation in immature morphology becomes evident.

Prey-capture in Pomacanthus semicirculatus (Teleostei,Pomacanthidae): functional implications of intramandibular joints in marine angelfishes

We examined prey-capture morphology and kinematics in the angelfish, Pomacanthus semicirculatus (Cuvier 1931), to evaluate the magnitude and role of functional specialisation. The feeding apparatus of P. semicirculatus possess three biomechanical mechanisms of particular interest: (1) a novel intramandibular joint, permitting dentary rotation and protruded jaw closure; (2) an opercular linkage facilitating mandible depression; and (3) a suspensorial linkage with two novel points of flexion, permitting anterior rotation of the suspensorium and augmenting mandible protrusion. Prey-capture kinematics were quantified using motion analysis of high-speed video, yielding performance profiles illustrating timing of onset, duration and magnitude of movement in these three biomechanical systems, and other variables traditionally quantified in studies of teleostean ram-suction feeding activity. Mandible depression and suspensorial rotation both augmented mandible protrusion, and coincided during jaw protrusion, typically increasing head length by 30%. Jaw closure appeared to result from contraction of the adductor mandibulae segment A2, which rotated the dentary by approximately 30 degrees relative to the articular. This resulted in jaw closure with the mandible fully depressed and the jaws at peak-protrusion. Feeding events were concluded by a high-velocity jaw retraction (20-50 ms), and completed in 450-750 ms. Feeding kinematics and morphology of Pomacanthus differed from other biting teleosts, and more closely resemble some long-jawed ram-suction feeders. The structural and functional modifications in the Pomacanthus feeding apparatus are matched to an unusual diet of structurally resilient and firmly attached benthic prey.

Ischemic preconditioning ameliorates ischemia- and reperfusion-induced intestinal epithelial hyperpermeability in rats.

We hypothesized that ischemic preconditioning (IPC) would ameliorate ischemia (I) and reperfusion (R)-induced intestinal mucosal hyperpermeability and that this effect would be diminished by lowering local adenosine concentrations using adenosine deaminase (ADA). The small intestine of anesthetized rats (group 1; n = 6) was divided into six 10-cm segments (A1-F1) each perfused by a different set of mesenteric branches. Segments D1-F1 were subjected to 3 cycles of IPC (2 min I/5 min R). Segments A1, B1, and C1 were excised at baseline, after 60 min of I (160), and after 60 min of I followed by 60 min of R (160/R60), respectively. Segment D1 was excised immediately after the last cycle of IPC, E1 was excised at 160 after IPC, and F1 was excised at 160/R60 after IPC. In group 2 (n = 6), the intestine was divided into five 10-cm vascularly isolated segments (A2-E2). Segment A2 was resected at baseline. The lumen of the remaining segments was filled with ADA (32 U/50 cm). Segment B2 was removed at the end of the experiment having been exposed to ADA for 150 min (ADA150). Segments C2, D2, and E2 were subjected to IPC. Segment C2 was excised immediately thereafter. Segments D2 and E2 were excised at 160 and 160/R60, respectively. Intestinal permeability to fluorescein isothiocyanate-labeled dextran (molecular weight 4000 D) was assessed ex vivo by using an everted gut sac method. IPC ameliorated intestinal hyperpermeability induced by 160 (43.0+/-7.6 vs. 70.4+/-8.3 nLmin/cm2; P = 0.024) and 160/R60 (20.2+/-3.7 vs. 69.5+/-10.8 nL/min/cm2; P= 0.003). IPC prevented ischemia-induced reduction in villus height. Treatment with ADA partially reversed the protective effect of IPC on the changes in permeability and villus height induced by I/R. We conclude that IPC partially protects against mucosal barrier dysfunction in rats subjected to mesenteric I/R. Adenosine is a mediator of IPC in the gut mucosa, but other factors also may be important.