Home About us Contact
|
Home About us Contact | ||
|
|
||
Posterior Edge (posterior + edge)
Selected AbstractsUltrastructural study of the jaw structures in two species of Ampharetidae (Annelida: Polychaeta)ACTA ZOOLOGICA, Issue 3 2004Alexander B. Tzetlin Abstract Two species of jaw bearing Ampharetidae (Adercodon pleijeli (Mackie 1994) and Ampharete sp. B) were investigated in order to describe the microanatomy of the mouth parts and especially jaws of these enigmatic polychaetes. The animals of both studied species have 14,18 mouth tentacles that are about 30 µm in diameter each. In both species, the ventral pharyngeal organ is well developed and situated on the ventral side of the buccal cavity. It is composed of a ventral muscle bulb and investing muscles. The bulb consists of posterior and anterior parts separated by a deep median transversal groove. In both species, the triangular teeth or denticles are arranged in a single transversal row on the surface of the posterior part of the ventral bulb just in front of its posterior edge. There are 36 denticles in Adercodon pleijeli and 50 in Ampharete sp. B. The height of the denticles (6,12 µm) is similar in both species. Each tooth is composed of two main layers. The outer one (dental) is the electron-dense sclerotized layer that covers the tooth. The inner one consists of long microvilli with a collagen matrix between them. The thickness of the dental layer ranges from 0.95 to 0.6 µm. The jaws of the studied worms may play a certain role in scraping off microfouling. The fine structure of the jaws in Ampharetidae is very similar to that of the mandibles of Dorvilleidae, the mandibles and the maxillae of Lumbrineridae, Eunicidae and Onuphidae, and the jaws of other Aciculata. This type of jaw is characterized by unlimited growth and the absence of replacement. The occurrence of jaws in a few smaller Ampharetidae is considered as an apomorphic state. [source] Balloon cell nevus of the pharynxHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 10 2004Achal Gulati MS Abstract Background. Mucosal melanotic lesions are rare, and the still rarer balloon cell variant has not been reported in the upper aerodigestive tract mucosa. We report a case of balloon cell nevus of the pharynx. Methods. A 35-year-old woman was seen with complaints of a black color in her mouth. Physical examination revealed a diffusely pigmented posterior pharyngeal wall. The pigmentation extended superiorly to the posterior edge of the palate, and laterally, it stopped short of the posterior tonsillar pillars. The overlying mucosa was smooth, with no swelling. Flexible endoscopy showed that the lesion extended to the cricopharynx. Findings on histopathologic examination were consistent with balloon cell nevus of the pharynx. Complete excision was not possible, because the lesion was very diffuse. Results. After 2 years of conservative management and regular follow-up examinations, no change in the symptoms and no increase in the lesion have been seen. Conclusion. Melanotic lesions in the upper aerodigestive tract mucosa are rare. This case is reported for its rarity, unusual presentation, and characteristic histopathologic features. © 2004 Wiley Periodicals, Inc. Head Neck26: 910,914, 2004 [source] Early results of a new open surgical technique for treatment of uretero-pelvic junction obstructionINTERNATIONAL JOURNAL OF UROLOGY, Issue 4 2006SAEED SHAKERI Objective:, Here we report our initial experience with a new open surgical technique for treating uretero-pelvic junction obstruction (UPJO). Methods:, One centimeter distal to the site of the uretero-pelvic junction (UPJ) stenosis, a longitudinal incision of about 15 mm was made over the lateral side of the ureter. The renal pelvis was evacuated. Simultaneously, an oblique incision was made over the posterior and anterior walls of the renal pelvis. The most dependent point over the renal pelvis was sutured to the distal end of the ureterotomy incision. The anterior edge of the pyelotomy incision was anastomosed to the anterior edge of the ureterotomy incision and the posterior edge was anastomosed to the posterior edge of the ureterotomy incision. When the pyeloplasty was completed, the UPJ, accompanied by the proximal 1 cm of the ureter and excessive parts of the renal pelvis, was excised. Results:, In 21 (92%) out of 23 patients, the surgical technique was successful. Conclusions:, This technique results in predictably good outcomes and has the advantages of the dismembered method. It seems to be a valuable alternative treatment for UPJO. [source] Acrossocheilus spinifer, a new species of barred cyprinid fish from south China (Pisces: Teleostei)JOURNAL OF FISH BIOLOGY, Issue SB 2006L. Y. Yuan Acrossocheilus spinifer sp. nov. is described from the river basins in Fujian Province and the Han Jiang basin in Guangdong Province, south China. It is one of the barred Acrossocheilus species sharing five or six vertical bars on the flanks, with each bar being two scales in width. Acrossocheilus spinifer sp. nov. is morphologically most similar to Acrossocheilus wenchowensis, but distinguished from it by: a colour pattern of all vertical bars extending ventrally to the second scale row below the lateral line, and having the second bar placed posterior to the base of the last simple dorsal-fin ray, a blunt snout; and a stout, last simple dorsal-fin ray. Acrossocheilus spinifer sp. nov. resembles Acrossocheilus kreyenbergii and Acrossocheilus stenotaeniatus with which it shares a stout, last simple dorsal-fin ray with a serrated posterior edge, but is separated from both species by having a narrow median interruption in the lower lip, a lower jaw fully covered by the lower lip when viewed ventrally and the second vertical bar placed posterior to the base of the last simple dorsal-fin ray. The absence of a longitudinal stripe extending along the lateral line on the flanks in males readily distinguishes A. spinifer sp. nov. from four other species, namely Acrossocheilus fasciatus, Acrossocheilus paradoxus, Acrossocheilus parallens, and Acrossocheilus jishouensis. [source] Octopus Gonadotrophin-Releasing Hormone: A Multifunctional Peptide in the Endocrine and Nervous Systems of the CephalopodJOURNAL OF NEUROENDOCRINOLOGY, Issue 4 2009H. Minakata The optic gland, which is analogous to the anterior pituitary in the context of gonadal maturation, is found on the upper posterior edge of the optic tract of the octopus Octopus vulgaris. In mature octopus, the optic glands enlarge and secrete a gonadotrophic hormone. A peptide with structural features similar to that of vertebrate gonadotophin-releasing hormone (GnRH) was isolated from the brain of octopus and was named oct-GnRH. Oct-GnRH showed luteinising hormone-releasing activity in the anterior pituitary cells of the Japanese quail Coturnix coturnix. Oct-GnRH immunoreactive signals were observed in the glandular cells of the mature optic gland. Oct-GnRH stimulated the synthesis and release of sex steroids from the ovary and testis, and elicited contractions of the oviduct. Oct-GnRH receptor was expressed in the gonads and accessory organs, such as the oviduct and oviducal gland. These results suggest that oct-GnRH induces the gonadal maturation and oviposition by regulating sex steroidogenesis and a series of egg-laying behaviours via the oct-GnRH receptor. The distribution and expression of oct-GnRH in the central and peripheral nervous systems suggest that oct-GnRH acts as a multifunctional modulatory factor in feeding, memory processing, sensory, movement and autonomic functions. [source] Kinematic analysis of kneeling in cruciate-retaining and posterior-stabilized total knee arthroplastiesJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 4 2008Satoshi Hamai Abstract Kneeling is an important function of the knee for many activities of daily living. In this study, we evaluated the in vivo kinematics of kneeling after total knee arthroplasty (TKA) using radiographic based image-matching techniques. Kneeling from 90 to 120° of knee flexion produced a posterior femoral rollback after both cruciate-retaining and posterior-stabilized TKA. It could be assumed that the posterior cruciate ligament and the post-cam mechanism were functioning. The posterior-stabilized TKA design had contact regions located far posterior on the tibial insert in comparison to the cruciate-retaining TKA. Specifically, the lateral femoral condyle in posterior-stabilized TKA translated to the posterior edge of the tibial surface, although there was no finding of subluxation. After posterior-stabilized TKA, the contact position of the post-cam translated to the posterior medial corner of the post with external rotation of the femoral component. Because edge loading can induce accelerated polyethylene wear, the configuration of the post-cam mechanism should be designed to provide a larger contact area when the femoral component rotates. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:435,442, 2008 [source] Ultrastructure and distribution of superficial neuromasts of blind cavefish, Phreatichthys andruzzii, juvenilesMICROSCOPY RESEARCH AND TECHNIQUE, Issue 9 2009Bahram S. Dezfuli Abstract Transmission and scanning electron microscopy (TEM, SEM) were used to study the ultrastructure of superficial neuromasts in 15 six-month old blind cavefish juveniles, Phreatichthys andruzzii (Cyprinidae). In five specimens examined with SEM, the number of superficial neuromasts over the fish body (480,538) was recorded. They were localized mainly on the head (362,410), including the dorsal surface, the mentomandibular region, and laterally from the mouth to the posterior edge of the operculum. Neuromasts were also present laterally on the trunk and near the caudal fin (116,140). A significantly higher number of neuromasts were present on the head compared to the trunk (t -test, P < 0.05). Superficial neuromasts of the head and those along the trunk were similar in ultrastructure. Each neuromast comprised sensory hair cells surrounded by nonsensory support cells (mantle cells and supporting basal cells) with the whole covered by a cupula. Each hair cell was pear-shaped, 15,21 ,m high and 4,6 ,m in diameter, with a single long kinocilium and several short stereocilia. Most support cells were elongated, with nuclei occupying a large portion of the cytoplasm. In the margin of the neuromast, mantle cells were particularly narrow. Both types of support cells had well-developed Golgi apparatus and rough endoplasmic reticulum. The number of hair cells and nonsensory support cells of the anterior lateral line (head) did not differ significantly from those of the posterior lateral line (trunk) (t -test, P > 0.05). Microsc. Res. Tech. 2009. © 2009 Wiley-Liss, Inc. [source] The treatment of uveal melanoma by ruthenium plaquesACTA OPHTHALMOLOGICA, Issue 2009B DAMATO Purpose Plaque radiotherapy is the first choice of treatment for choroidal melanomas. The standard practice is to position the plaque centrically in relation to the tumour, with a 2mm physical safety margin in all directions. The author has developed techniques for administering brachytherapy with plaques positioned eccentrically, with their posterior edge aligned with the posterior tumour margin. This allows a higher apex dose to be given while reducing the radiation delivered to optic nerve and fovea. Methods The tumour is localized by transillumination and its anterior margin marked on the sclera with a pen. The 'plaque-tumour difference' measurement is then marked on the sclera at the point where the anterior plaque margin should be. A transparent plaque template is sutured to the sclera. The position of the plaque is checked with a right-angled fibre-optic transilluminator, which is passed through a perforation near the posterior edge of the template. If the template is positioned correctly, then with binocular indirect ophthalmoscopy one should see the 'sunset sign', which occurs when the transilluminator is exactly at the posterior tumour margin. Results Eccentric ruthenium plaque positioning has been practised in Liverpool for over a decade. The results have been published. Local tumour control rates have been good (partly because of case selection). Radiation maculopathy and optic neuropathy have been rare if the tumour has not extended within 1 mm of these structures. The main cause of visual loss has been maculopathy, caused by exudation from the irradiated tumour. Methods for treating such exudation are described. Conclusion Plaque radiotherapy is effective for choroidal melanomas up to 5 mm in thickness. It achieves good local tumour control with preservation of vision in most cases. [source] An audit of eccentrically-positioned ruthenium plaque radiotherapy of choroidal melanoma in LiverpoolACTA OPHTHALMOLOGICA, Issue 2009A RUSSO Purpose Brachytherapy is usually administered with the plaque overlapping the entire tumour margin by at least 1-2mm. With posterior tumours, our practice is to position the plaque with its posterior edge aligned with the posterior tumour margin. We audited ocular outcomes after eccentrically-placed ruthenium plaque radiotherapy of choroidal melanoma. Methods Patients were included if receiving primary ruthenium brachytherapy for choroidal melanoma during the three years up to the 31st July 2007. A perforated template was used to facilitate plaque positioning. For posterior tumors, the template was positioned so that trans-illumination produced a glow at the posterior tumour margin (,sunset sign'). Minimum doses of 300-350 Gy and 80-90 Gy were prescribed to the sclera and apex, respectively. Results The cohort comprised 162 patients (93 female and 69 male). The time to the last known visual acuity had a median of 23 months. The initial visual acuity was 20/40 or better in 94.6%, 20/60 to 20/200 in 13.0% and worse than 20/200 in 1.9% of patients. The tumours had a mean basal diameter of 11.7mm. Ten tumours exceeded 5.4 mm in height. Tumour extension to within 5mm of optic disc, fovea or both occurred in 18 (11.1%), 28 (17.3%) and 27 (16.7%) cases respectively. Risk factors for visual loss were proximity to optic disc or fovea, initial visual acuity worse than 20/40 and tumour height exceeding 5.4 mm. In 66 patients with none of these risk factors, 92% retained 20/40 or better and 5 had vision of 20/60 , 20/200. In 72 with one risk factor, 74.3% retained 20/16 , 20/40 and 95.7% had vision of 20/200 or better. In 12 patients with 2 risk factors, these percentages were 25.0% and 91.7%. Only 3 patients had 3 risk factors and one retained vision of 20/200 or better. Tumours distanced < 5 mm to fovea were divided in 3 groups, and visual acuity analysed. Three patients had local tumour recurrence and were treated respectively by proton beam radiotherapy, plaque radiotherapy and enucleation (the only eye lost in this series). Conclusion Eccentric plaque radiotherapy of choroidal melanoma achieves good rates of local tumour control, ocular retention and preservation of vision. [source] The effect of scleral flap edge apposition on intraocular pressure control in experimental trabeculectomyCLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 4 2008Wayne Birchall Abstract Background:, To assess the contribution of scleral flap edge apposition to intraocular pressure (IOP) control in trabeculectomy, using a previously described and validated experimental model of guarded filtration surgery. Materials and methods:, Twelve rectangular-flap trabeculectomy operations each with two apical adjustable sutures were performed on six donor human eyes connected to a constant flow infusion with real-time IOP monitoring. Three sizes of scleral flap were created: 4 × 4 mm, 16 mm2 (n = 4), 3 × 3 mm, 9 mm2 (n = 4) or 3 × 2 mm, 6 mm2 (n = 4). Sutures were tied tightly to produce high aqueous outflow resistance, and equilibrium IOP established. The lateral and posterior edges of the scleral flap were removed, the sutures tightened again, and the new equilibrium IOP measured. Results:, Following flap closure and with intact flap edges, the mean absolute IOP for all flaps (n = 12) was 19.5 ± 3.9 mm Hg (mean ± SD, range 12.4,27 mm Hg) and following flap edge excision 18.7 ± 4.4 mm Hg (range 5.6,27.9 mm Hg), demonstrating no significant difference between flaps with edge apposition compared with those without (P = 0.33). Mean relative IOP (% of baseline) was 68.4 ± 12.1% (range 40.9,94%) with intact flap edges and 65.4 ± 14.5% (range 18.5,97.2%) following flap edge excision (P = 0.31). Flaps measuring 4 × 4 mm and 3 × 3 mm behaved in a similar manner with minimal change in equilibrium IOP following excision of flap edges. Conclusions:, In this experimental model, scleral flap edge apposition is not required for generating outflow resistance. Suture tension generated during tight flap closure produces apposition of the underside of the scleral trapdoor to the underlying bed, and it is this apposition, which determines IOP. [source] | |||||||||||||