Structural organization in leaf blade and sheath of elephant-grass cultivars (Pennisetum purpureum Schum. - POACEAE).

Elephant-grass is known as a great feed to dairy and beef cattle at tropical regions. Its agricultural aspects have been very observed. However, its botanical, mainly anatomical characteristics, are few studied. The objective of this work was to investigate the anatomical changes occurred in leaves (leaf blades and sheaths) of three elephant-grass cultivars (Pennisetum purpureum Schum. cultivar Roxo, EMPASC 307 Testo and EMPASC 309 Areia) at three stages of physiological maturity (4, 8 and 16 weeks after sprouting). In general, the three cultivars presented similar anatomy. A unique feature, the presence of aerenchyma was found in the leaf sheath of all three cultivars, at the second harvest (a weeks).

Localization and irregular distribution of Na,K-ATPase in myelin sheath from rat sciatic nerve

Sodium, potassium adenosine triphosphatase (Na,K-ATPase) is a membrane-bound enzyme that maintains the Na+ and K+ gradients used in the nervous system for generation and transmission of bioelectricity. Recently, its activity has also been demonstrated during nerve regeneration. The present study was undertaken to investigate the ultrastructural localization and distribution of Na,K-ATPase in peripheral nerve fibers. Small blocks of the sciatic nerves of male Wistar rats weighing 250-300g were excised, divided into two groups, and incubated with and without substrate, the para-nitrophenyl phosphate (pNPP). The material was processed for transmission electron microscopy, and the ultra-thin sections were examined in a Philips CNI 100 (TM) electron microscope. The deposits of reaction product were localized mainly on the axolemma, on axoplasmic profiles, and irregularly dispersed on the myelin sheath, but not in the unmyelinated axons. In the axonal membrane, the precipitates were regularly distributed on the cytoplasmic side. These results together with published data warrant further studies for the diagnosis and treatment of neuropathies with compromised Na,K-ATPase activity. (c) 2007 Elsevier Ltd. All rights reserved.

GENETIC INSTABILITY IN NERVE SHEATH CELL TUMORS

After in vitro culture, we analyzed cytogenetically four acoustic nerve neurinomas, one intraspinal neurinoma and one neurofibroma obtained from unrelated patients. Monosomy of chromosomes 22 and 16 was an abnormality common to all cases, followed in frequency by loss of chromosomes 18 (three cases) and chromosomes 8, 17 and 19 (two cases). Trisomy of chromosome 20 was also detected in two cases. Structural rearrangements were detected at low frequencies, with del(10)(p12) being present in two cases. In addition, we observed cell subpopulations showing a certain degree of genetic instability, reflected by the presence of polyploid cells with inconsistent abnormalities, endoreduplications and telomeric associations resulting in dicentric chromosomes. It is probable that these cytogenetic abnormalities represent some kind of evolutionary advantage for the in vitro progression of nerve sheath tumors.

Connective tissue graft to correct peri-implant soft tissue margin: A clinical report

This clinical report describes the use of a subepithelial connective tissue graft to recontour a soft tissue margin discrepancy for a single-implant crown in the anterior maxilla. This procedure demonstrates that the use of soft tissue grafts to correct an esthetic deficiency may be a feasible approach to establish new and stable peri-implant soft tissue contours. The patient presented was followed for 18 months.

Anomalous transport effects on magnetic field profile in a motional current sheath

The radial magnetic field profile during implosion of a reversed field current sheath in a theta-pinch was investigated through local measurements and simulation of hybrid code. The actual profile was defined by Hermite interpolation polynomial through mean value of the field at discrete radial position of measurements. Simulation profile was provided by the numerical code with appropriate initial conditions. Classical and anomalous collision process were taken in account in the theoretical model. The results indicated that anomalous effects play major role during the implosion phase of current sheath in a slow rising theta pinch device.

Ultrastructure of the ovariole sheath in Diatraea saccharalis (Lepidoptera : Pyralidae)

The ultrastructure of the ovariole sheath along the Diatraea saccharalis ovariole was studied by scanning and transmission electron microscopy. Each ovariole is surrounded by an epithelial sheath, a tunica propria and scattered lumen cells. These three components of the ovariole sheath show different ultrastructural features along the ovariole, in the germarium or in the vitellarium; these differences are more evident in the epithelial sheath cells. The epithelial sheath is composed by two layers of cells, the external one running longitudinally and the internal one running circularly in the ovariole. These cells, in vitellarium, present cytoplasmic bundles of myofilaments that are arranged parallel to the long axis of the cells; these myofilaments are apparently related to the contraction movements of the follicles within the ovariole. The acellular tunica propria, composed of finely filamentous material, is attached to the adjacent follicle cells by adhesive dense plates. Between the epithelial sheath and the tunica propria there is a population of lumen cells, with morphological features of secretory activity.

Establishment of the epithelial attachment and connective tissue adaptation to implants installed under the concept of "platform switching": a histologic study in minipigs

Aim: To validate the platform switching concept at oral implants with respect to the preservation of the alveolar crestal bone levels in an animal model. Material & methods: Five minipigs received three implants each with a 0.25mm implant/ abutment mismatch and were placed flush (T(0)), 1 mm below (T(1)) and 1 mm above (T(+1)) the alveolar bony crest, and as a control, one conventionally restored implant placed at the bone level. The implants were randomly inserted flapless into the mandible. Four months after implant insertion, the animals were sacrificed, and undecalcified block sections were obtained and used for histological analyses. Results: The mean values for peri- implant bone resorption were 1.09 +/- 0.59mm (Control), 0.51 (+/- 0.27 mm, T(0)), 0.50 (+/- 0.46 mm, T(1)) and 1.30 (+/- 0.21 mm, T (+1)), respectively. Statistically significant differences (P< 0.05) were found among the test (T(0), T(-1)) and the control sites. Control implants presented an average biologic width length of 3.20mm (+/- 0.33), with a connective tissue adaptation compartment of 1.29mm (+/- 0.53) and an epithelial attachment of 1.91 mm (+/- 0.71). T(0), T(1) and T(+1) implants presented with a mean biologic width of 1.97mm (+/- 1.20), 2.70 mm (+/- 1.36) and 2.84mm (+/- 0.90), respectively, with a connective tissue adaptation compartment of 1.21mm (+/- 0.97), 1.21 mm (+/- 0.65) and 1.50 mm (+/- 0.70) and an epithelial attachment of 0.84 mm (+/- 0.93), 1.66 mm (+/- 0.88) and 1.35 mm (+/- 0.44), respectively. Differences between the configurations were mainly associated with the length of the epithelial attachment. The epithelial attachment was significantly longer in the C sites than in T(0) (P = 0.014). However, no other differences between configurations were detected. Conclusion: If the implants are positioned at the level of the alveolar bony crest, the platform switching concept may have a minor impact on the length of the epithelial attachment (0.84 vs. 1.91 mm), while the connective tissue adaptation compartment remains relatively unaffected. Moreover, platform switching resulted in less resorption of the alveolar crest (0.58 mm).

Comparison of subcutaneous connective tissue responses among three different formulations of gutta-percha used in thermatic techniques.

A study of the subcutaneous connective tissue response of 24 white rats to three different formulations of gutta-percha was undertaken. The prepared specimens were examined under the light microscope after intervals of 7, 21, 60 and 120 days. The results showed identical tissue responses after the initial period of 7 days. However, after 120 days the gutta-percha supplied with the Ultrafil system presented mature granulation tissue with neither oedema nor vascular congestion, in contrast to the responses observed with the McSpadden and Obtura formulations.