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.

Complete staining of nerve fiber and myoneural junctions with acetylthiocholine and silver

We describe a combined stain for simultaneous demonstration of the preterminal axons and cholinesterase activity at myoneural junctions of mammalian muscles. This technique employs acetylthiocholine iodide as the substrate for cholinesterase activity and silver nitrate impregnation of preterminal axons. The procedure is rapid, simple and uses fresh muscles. Intramuscular nerves, preterminal axons and myoneural junctions are stained simultaneously brown or black with minimal background staining of connective tissue and muscle fibers.

Ultrastructure of the Lyonet's glands in larvae of Diatraea saccharalis Fabricius (Lepidoptera : Pyralidae)

The Lyonet's gland is found in Lepidoptera larvae, close to the excretory duct of the silk gland. The role played by this gland is still uncertain. This work aims to describe the ultrastructure of the Lyonet's bland in Diatraea saccharalis larvae, offering suggestions regarding its possible function. The insects were reared under laboratory-controlled conditions. The glands were conventionally prepared for transmission (TEM) and scanning (SEM) electron microscopy. SEM showed that Lyonet's glands are paired small structures located in the ventral side of the head. They are composed by clustered long cells resembling leaves. Under TEM observations, each cell is surrounded by a thin basal lamina and contains large stellate nucleus. The cytoplasm presents large and empty canaliculi with small microvilli. The basal plasma membrane forms numerous infoldings where numerous and well-developed mitochondria are concentrated. The cytoplasmic membrane system is poorly developed. Our ultrastructural results suggest that the Lyonet's gland in D. saccharalis larvae may be involved in the uptake of small molecules from the hemolymph no morphological evidences of macromolecules synthesis and secretion were noticed. The detection of nerve fibers in the gland suggest a neural control for the glandular cell function.

Effect of high laryngeal mask airway intracuff pressure on the laryngopharyngeal mucosa of dogs

Objectives: To evaluate the effect of increased of laryngeal mask airway (LMA) intracuff pressures on the laryngopharyngeal mucosa. Study Design: Animal model. Methods: Sixteen mixed-breed dogs were randomly allocated to two groups, G1 (intracuff volume, 30 mL; n = 8) and G2 (intracuff volume, 54 mt; n = 8), to produce, respectively, high or very high intracuff pressures. Anesthesia was induced and maintained with pentobarbital. Intracuff pressures were measured immediately after insertion and inflation of a No. 4 laryngeal mask airway (LMA) and 30, 60, 90, and 120 minutes thereafter. The dogs were euthanized, and biopsy specimens from eight predetermined areas of the laryngopharynx in contact with LMA cuff were collected for light microscopic (LM) and scanning electron microscopic (SEM) examination. Results: Initial LMA cuff inflation in G1 and G2 resulted in intracuff pressures of 119 mm Hg +/- 4 mm Hg and 235 mm Hg +/- 13 mm Hg, respectively. Over a 2-hour period, the intracuff pressure decreased significantly in G1 (P < .001) and G2 (P < .01), and there was a significant difference between the groups over time (P < .001). The LM study of laryngopharyngeal mucosa in both groups showed mild congestion in the subepithelial layer. There were no differences between the groups (P > .10) or among the areas sampled (P > .10). In some areas of G2, the SEM study showed epithelial desquamation that was more intense than that in GI. Conclusions: the increase in LMA intracuff pressure caused only mild alterations in the laryngopharyngeal mucosa of the dog.

MULLER CELLS AND DIABETIC-RETINOPATHY

Muller cells provide nutrition for neural cells. We studied the structure and ultrastructure of Muller cells in the retina of thirty 3-month old Wistar rats; divided equally into 3 groups: normal rats, alloxan diabetic rats and treated alloxan diabetic rats. 1 and 12 months after induction of diabetes. We observed that the Muller cell nuclei under light microscope examination had hexagonal shape and higher density than the other nuclei. Differences between groups could be observed only by electron microscopy. In the diabetic rats, Muller cells presented dispersion of nuclear chromatin and electrondense nuclear granulations, with the presence of increased glycogen, dense bodies and lysosomes in the cytoplasm. The alterations were more frequent in the perivascular region and at 12 months. The treated diabetic rats exhibited some alterations we observed in diabetic rats. but these alterations were less intense. We conclude that, despite the treatment, the diabetic retinopathy continues to evolve.

Lidocaine effects on corneal endothelial cell ultrastructure

The purpose of this study was to determine whether intracameral commercial lidocaine 2% induces alterations on the rabbit corneal endothelium. Forty white rabbits received different substances inside the anterior chamber: group (G)1, no substance; G2 and G3 received lidocaine 2% with preservative in aqueous solution; G4 and G5, lidocaine 2% with preservative in gel solution; G6 and G7, the anesthetic preservative (metilparahydroxybenzoate 0.1%); and G8 and G9, lidocaine 2% without preservative in aqueous solution. The animals from G2, 4, 6 and 8 were sacrificed after 1 h, and from G3, 5, 7 and 9 after 24 h after injection of the substance inside the anterior chamber. The corneas were clinically evaluated and assessed by transmission and scanning electron microscopy. G1, 2, 6, 7, 8 and 9 animals had very similar characteristics in clinical, ultrastructural and morphometric evaluations; the G3 and G4 animals showed discrete edema and one animal in G5 had intense corneal edema. We conclude that lidocaine 2% with preservative induces few ultrastructural alterations in the corneal endothelial cells.

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.

Morphological and quantitative aspects of nodule formation in hemolymph of the blowfly Chrysomya megacephala (Fabricius, 1794)

Insects manifest effective immune responses that include both cellular and humoral components. Morphological and quantitative aspects of cellular and Immoral cooperation during nodule formation in Chrysomya megacephala hemolymph against Saccharomyces cerevisae yeast cells were demonstrated for the first time. The analyses were performed in non-injected larvae (NIL), saline-injected larvae (SIL) and yeast-injected larvae (YIL). The hemolymph of injected groups was collected 0.5, 1, 2, 4, 12, 24, 36, or 48-h post-injection. Morphological aspects of YIL nodulation were investigated using transmission electron microscopy (TEM). Quantitative analyses consisted of total (THC) and differential hemocyte counts (DHC) in all the groups and total yeast count (TYC) in YIL, which were performed in an improved Neubauer chamber. Nodule formation was initiated at approximately 2-h post-injection. Twelve hours after the injection, TEM revealed the presence of an amorphous membrane, at the same time that circulating hemocyte number decreased significantly contrasting the increase of yeast number. Our results showed the ability of C megacephala hemolymph to perform humoral encapsulation when hemocyte population is insufficient to eliminate the microorganisms, warranting consideration in future investigations on the relative roles played by cellular and humoral elements of innate immunity of this calliphorid. (c) 2007 Elsevier B.V. All rights reserved.

Effects of Passiflora edulis on the Metabolic Profile of Diabetic Wistar Rat Offspring

Dry extract of the genus Passiflora has been shown to help control glycemia and lipid levels. The objective of this study was to evaluate the effects of passion fruit (P. edulis) on the biochemical profile of offspring from diabetic rats. Diabetes was induced by streptozotocin. The diabetes group consisted of 10 rats with glucose levels greater than 200 mg/dL; the nondiabetic (control) group consisted of 10 rats with glucose levels less than 120 mg/dL. After the diagnosis of diabetes, the mating phase was started. By day 21 of pregnancy, the offspring were born; the dams were kept in individual cages with their offspring until the weaning period. The offspring were then divided into 4 groups (n = 15 each): G1 were offspring from control dams, G2 were offspring from treated nondiabetic dams, G3 were offspring from diabetic dams, and G4 were offspring from treated diabetic dams. For 30 consecutive days, G1 and G3 offspring were treated with vehicle (oral gavage) and G2 and G4 offspring were treated with passion fruit juice (oral gavage). After 30-day treatment, the animals were anesthetized and killed, and blood was drawn immediately for analysis of the biochemical profile (total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, and glucose). The G2 and G4 rats showed significantly reduced total cholesterol, triglyceride, and low-density lipoprotein cholesterol levels and an increased high-density lipoprotein cholesterol level. The use of passion fruit juice improved lipid profiles, suggesting that this plant may have beneficial effects in the prevention and treatment of dyslipidemias and hyperglycemia.