Closure of large wounds using rubber bands in rabbits

OBJECTIVE: to verify the effectiveness of the rubber elastic band in the treatment of large wounds of the body wall of rabbits by means of traction of its edges. METHODS: we studied 30 New Zealand rabbits, divided into three groups (n=10): Group 1- healing by secondary intention; Group 2- removal and eutopic repositioning of skin as full thickness skin graft; Group 3- Approximation of wound edges with elastic rubber band. In all animals, we removed a segment of the back skin and subcutaneous tissue down to the fascia, in accordance with an acrylic mold of 8cm long by 12cm wide. All animals were observed for 21 days. RESULTS: two animals of groups 1 and 2 had wound abscess. In Group 2, there was partial or total graft loss in 90% of animals. The complete closure of the wounds was observed in four animals of Group 1, six of Group 2 and eight of Group 3. There was no difference between the scar resistance values of groups 2 and 3, which were higher than those in Group 1. The scars of the three groups were characterized by the presence of mature connective tissue mixed with blood vessels and inflammatory infiltration, predominantly polymorphonuclear. CONCLUSION: the tensile strength of the wound edges with rubber elastic band is as efficient as the skin graft to treat rabbits' large body wounds.

Isolation, expansion and differentiation of cellular progenitors obtained from dental pulp of agouti (Dasyprocta prymnolopha Wagler, 1831)

Abstract: The study aimed to isolate, expand, differentiate and characterize progenitor cells existent in the dental pulp of agouti. The material was washed with PBS solution and dissociated mechanically with the aid of a scalpel blade on plates containing culture medium D-MEM/F-12, and incubated at 5% CO2-37⁰C. The growth curve, CFU assay, osteogenic/adipogenic differentiation and characterization were obtained from the isolation. The cells began to be released from the explant tissue around the 7th day of culture. By day 22 of culture, cells reached 80% confluence. At the UFC test, 81 colonies were counted with 12 days of cultivation. The growth curves before and after freezing showed a regular growth with intense proliferation and clonogenic potential. The cell differentiation showed formation of osteoblasts and fat in culture, starting at 15 days of culture in a specific medium. Flow cytometry (FACs) was as follows: CD34 (positive), CD14 (negative), CD45 (negative), CD73 (positive), CD79 (negative), CD90 (positive), CD105 (positive), demonstrating high specificity and commitment of isolated cells with mesenchymal stem cells strains. These results suggest the existence of a cell population of stem cells with mesenchymal features from the isolated tissue in the explants of agouti dental pulp, a potential model for study of stem cell strains obtained from the pulp tissue.

Development, structure and distribution of colleters in Mandevilla illustris and M. velutina (Apocynaceae)

Colleters of Mandevilla illustris and M. velutina are present on the cotyledons, shoot apices, mature leaves and on the nodal region, where they are interpetiolar and intrapetiolar. In M. velutina there are two colleters on the adaxial basal part of the leaf blade, and in M. illustris, this number varies. The differentiation of the colleters occurs in the early stages of leaf development. When colleters are mature, they consist of a long head on a short stalk. The central core of the colleter is made up of parenchymatous cells that may exhibit phenolic compounds and is surrounded by radially elongated epithelial cells. The foliar and intrapetiolar colleters can exhibit vascularization. The colleters produce a translucient sticky substance that reacts positively to polysaccharides and, before senescence, they produce lipophilic substances. The Mandevilla colleters data can give support to the taxonomy and phylogeny of the Apocynaceae.

Morphology and anatomy in Heliconia angusta Vell. and H. velloziana L. Emygd. (Zingiberales: Heliconiaceae) from the Atlantic forest of southeastern Brazil

Morphological and anatomical features of roots, stems, leaves, and scapes were studied in Heliconia angusta and H. velloziana from the Atlantic forest in the southeastern of Brazil. Morphologically H. angusta and H. velloziana show differences in their sizes, blade shapes, number and shape of inflorescence bracts. On the other hand, they have common anatomical characteristics such as: roots with air-canals in the cortex; rhizomes with isolated fiber bundles, collateral vascular bundles, and uniseriate endodermis and pericycle; leaves presenting air-canals and collateral vascular bundles forming arcs, and thin-walled epidermal cells; scapes with collateral vascular and fiber bundles in the cortex. The distribution of the fiber bundles in the leaves and in the scapes was different for each species, having a taxonomical value, H. velloziana presenting continuous fiber bundles. Air-canals in roots and leaves with narrow mesophyll might be related to the moist understorey of the Atlantic forest habitats.

Leaf anatomy variation within and between three "restinga" populations of Erythroxylum ovalifolium Peyr: (Erythroxylaceae) in Southeast Brazil

Erythroxylum ovalifolium is a woody shrub widespread in the "restinga", i.e. the open scrub vegetation of the Brazilian coastal sandy plains. We examined leaf anatomy variation of this species both within populations and between populations of three "restingas" in the state of Rio de Janeiro. Sites were ca.100 km far from each other and differed in regard to rainfall and vegetation structure: a dry, open site; a wet, dense site and an intermediate one. Microhabitats within sites were: (i) exposed to full irradiance, outside vegetation islands; (ii) partially exposed to full irradiance, at the border of vegetation islands; (iii) shaded, inside vegetation islands. Leaf anatomy parameters were measured for five leaves collected in each of five plants per microhabitat, in each population; they were thickness of the leaf blade, of the palisade and spongy parenchyma, and of the adaxial and abaxial epidermis. Leaves from the dry, open site had narrower abaxial epidermis and a smaller contribution of spongy parenchyma to total leaf blade thickeness than the other two sites, which we attributed to water stress. Adaxial epidermis and leaf are thicker in more exposed microhabitats (i and ii, above), irrespective of site. We proposed that between-site anatomical variation in traits related to water stress, and within-site anatomical variation in traits related to light-use are indicative of ecological plasticity and might help explain the high abundance of E. ovalifolium in the studied populations and along the State of Rio de Janeiro coast.

Growth and reproduction of the understory palm Geonoma schottiana Mart. in the gallery forest in Central Brazil

To understand the growth and reproduction of the palm Geonoma schottiana in the gallery forest of Central Brazil, two hypotheses were raised: (i) production of leaves and reproductive structures are concentrated in the period of the year with high light availability; (ii) leaf production and reproductive activity are related to plant length. However, it is expected that senility effects will cause fast reduction in growth and reproduction activities in higher plants. Growth and reproduction were concentrated in the dry season, when insolation is higher than in the wet season, suggesting that leaf and inflorescence production on G. schottiana in the gallery forest understory is more limited by light than by soil humidity. As the individual grows, leaf number and blade area increase, but reproduction activity is independent of plant length. Resources stored in the stem are important to growth, but exogenous factors, as canopy openness, should be more important to reproduction. Plant senescence seems to have a lesser effect on the production of vegetative and reproductive structures in G. schottiana than has been detected in congeneric species with greater clonal activity.

Ontogenesis of stomata in Velloziaceae: paracytic versus tetracytic?

In Velloziaceae, the number of subsidiary cells has been used to characterize species and support groups. Nevertheless, the homology of the stomatal types have not been scrutinized. Stomatal ontogenesis of Vellozia epidendroides and V. plicata, assigned to have tetracytic stomata, and of V. glauca and Barbacenia riparia, assigned to have paracytic stomata, were investigated. In the four species studied, stomata followed perigenic development. Subsidiary cells arise from oblique divisions of neighbouring cells of the guard mother cell (GMC). These cells are elongated and parallel to the longer axis of the stoma. Polar cells show wide variation, following the shape and size of the epidermal cells in the vicinity. Hence, these cells cannot be called subsidiary cells. This wide variation is due to a much higher density of stomata in some regions of the leaf blade. This distribution of stomata forces the development of short polar cells, leading to an apparently tetracytic stomata. In regions of low concentration of stomata, higher spatial availability between the GMCs allows the elongation of polar cells, leading to evident paracytic stomata. Therefore, the four studied species are considered braquiparacytic, questioning the classification of stomata into tetracytic and paracytic in Velloziaceae.

Anatomy, ultrastructure and secretion of Hibiscus pernambucensis Arruda (Malvaceae) extrafloral nectary

This paper reports on the extrafloral nectary (EFN) of Hibiscus pernambucensis, a native shrub species occurring in mangrove and restinga along Brazil's coastline. EFNs occur as furrows with a protuberant border on the abaxial surface veins of the leaf blade. Each nectary consists of numerous secretory multicellular trichomes, epidermal cells in palisade-like arrangements and non-vascularized parenchyma tissue. Nectar secretion is prolonged, since secretion starts in very young leaves and remains up to completely expanded leaves. Reduced sugars, lipids, and proteins were histochemically detected in all the nectary cells; phenolic substances were detected in the vacuoles of the epidermal palisade cells and in some secretory trichome cells. The secretory cells that constitute the body of trichomes have large nuclei, dense cytoplasm with numerous mitochondria, dictyosomes, scattered lipid droplets and plastids with different inclusions: protein, lipid droplets or starch grains; vacuoles with different sizes have membranous material, phenolic and lipophilic substances. The palisade cells show thick periclinal walls, reduced cytoplasm with voluminous lipid drops and developed vacuoles. The nectary parenchyma cells contain abundant plasmodesmata and cytoplasm with scattered lipid droplets, mitochondria, plastids with starch grains and endoplasmic reticulum. Mucilage idioblasts are common in the inner nectary parenchyma. Protoderm and ground meristem participate in the formation of EFN. Our data indicate that all nectary regions are involved in nectar production and secretion, constituting a functional unit. Longevity of the extrafloral nectaries is likely associated with the presence of mucilage idioblasts, which increases the capacity of the nectary parenchyma to store water.

Increased angiotensin-converting enzyme activity in the left ventricle after infarction

An increase in angiotensin-converting enzyme (ACE) activity has been observed in the heart after myocardial infarction (MI). Since most studies have been conducted in chronically infarcted individuals exhibiting variable degrees of heart failure, the present study was designed to determine ACE activity in an earlier phase of MI, before heart failure development. MI was produced in 3-month old male Wistar rats by ligation of the anterior branches of the left coronary artery, control rats underwent sham surgery and the animals were studied 7 or 15 days later. Hemodynamic data obtained for the anesthetized animals showed normal values of arterial blood pressure and of end-diastolic pressure in the right and left ventricular cavities of MI rats. Right and left ventricular (RV, LV) muscle and scar tissue homogenates were prepared to determine ACE activity in vitro by measuring the velocity of His-Leu release from the synthetic substrate Hyp-His-Leu. ACE activity was corrected to the tissue wet weight and is reported as nmol His-Leu g-1 min-1. No significant change in ACE activity in the RV homogenates was demonstrable. A small nonsignificant increase of ACE activity (11 &plusmn; 9%; P0.05) was observed 7 days after MI in the surviving left ventricular muscle. Two weeks after surgery, however, ACE activity was 46 &plusmn; 11% (P<0.05) higher in infarcted rats compared to sham-operated rats. The highest ACE activity was demonstrable in the scar tissue homogenate. In rats studied two weeks after surgery, ACE activity in the LV muscle increased from 105 &plusmn; 7 nmol His-Leu g-1 min-1 in control hearts to 153 &plusmn; 11 nmol His-Leu g-1 min-1 (P<0.05) in the remaining LV muscle of MI rats and to 1051 &plusmn; 208 nmol His-Leu g-1 min-1 (P<0.001) in the fibrous scar. These data indicate that ACE activity increased in the heart after infarction before heart failure was demonstrable by hemodynamic measurements. Since the blood vessels of the scar drain to the remaining LV myocardium, the high ACE activity present in the fibrous scar may increase the angiotensin II concentration and decrease bradykinin in the cardiac tissues surrounding the infarcted area. The increased angiotensin II in the fibrous scar may contribute to the reactive fibrosis and hypertrophy in the left ventricular muscle surviving infarction

Effect of epithelial debridement on human cornea proteoglycans

Corneal transparency is attributed to the regular spacing and diameter of collagen fibrils, and proteoglycans may play a role in fibrillogenesis and matrix assembly. Corneal scar tissue is opaque and this opacity is explained by decreased ultrastructural order that may be related to proteoglycan composition. Thus, the objectives of the present study were to characterize the proteoglycans synthesized by human corneal explants and to investigate the effect of mechanical epithelial debridement. Human corneas unsuitable for transplants were immersed in F-12 culture medium and maintained under tissue culture conditions. The proteoglycans synthesized in 24 h were labeled metabolically by the addition of 35S-sulfate to the medium. These compounds were extracted by 4 M GuHCl and identified by a combination of agarose gel electrophoresis, enzymatic degradation with protease and mucopolysaccharidases, and immunoblotting. Decorin was identified as the main dermatan sulfate proteoglycan and keratan sulfate proteoglycans were also prominent components. When the glycosaminoglycan side chains were analyzed, only keratan sulfate and dermatan sulfate were detected (~50% each). Nevertheless, when these compounds were 35S-labeled metabolically, the label in dermatan sulfate was greater than in keratan sulfate, suggesting a lower synthesis rate for keratan sulfate. 35S-Heparan sulfate also appeared. The removal of the epithelial layer caused a decrease in heparan sulfate labeling and induced the synthesis of dermatan sulfate by the stroma. The increased deposit of dermatan sulfate proteoglycans in the stroma suggests a functional relationship between epithelium and stroma that could be related to the corneal opacity that may appear after epithelial cell debridement.

Schwann cells for spinal cord repair

The complex nature of spinal cord injury appears to demand a multifactorial repair strategy. One of the components that will likely be included is an implant that will fill the area of lost nervous tissue and provide a growth substrate for injured axons. Here we will discuss the role of Schwann cells (SCs) in cell-based, surgical repair strategies of the injured adult spinal cord. We will review key studies that showed that intraspinal SC grafts limit injury-induced tissue loss and promote axonal regeneration and myelination, and that this response can be improved by adding neurotrophic factors or anti-inflammatory agents. These results will be compared with several other approaches to the repair of the spinal cord. A general concern with repair strategies is the limited functional recovery, which is in large part due to the failure of axons to grow across the scar tissue at the distal graft-spinal cord interface. Consequently, new synaptic connections with spinal neurons involved in motor function are not formed. We will highlight repair approaches that did result in growth across the scar and discuss the necessity for more studies involving larger, clinically relevant types of injuries, addressing this specific issue. Finally, this review will reflect on the prospect of SCs for repair strategies in the clinic.

Hypoglycemic activity of polysaccharide fractions containing ß-glucans from extracts of Rhynchelytrum repens (Willd.) C.E. Hubb., Poaceae

ß-Glucans are soluble fibers with physiological functions, such as interference with absorption of sugars and reduction of serum lipid levels. The objective of the present study was to analyze the distribution of ß-glucans in different tissues of the African grass species Rhynchelytrum repens and also to evaluate their hypoglycemic activity. Leaf blades, sheaths, stems, and young leaves of R. repens were submitted to extraction with 4 M KOH. Analysis of the fractions revealed the presence of arabinose, glucose, xylose, and traces of rhamnose and galactose. The presence of ß-glucan in these fractions was confirmed by hydrolyzing the polymers with endo-ß-glucanase from Bacillus subtilis, followed by HPLC analysis of the characteristic oligosaccharides produced. The 4 M KOH fractions from different tissues were subjected to gel permeation chromatography on Sepharose 4B, with separation of polysaccharides with different degrees of polymerization, the highest molecular mass (above 2000 kDa) being found in young leaves. The molecular mass of the leaf blade polymers was similar (250 kDa) to that of maize coleoptile ß-glucan used for comparison. The 4 M KOH fraction injected into rats with streptozotocin-induced diabetes showed hypoglycemic activity, reducing blood sugar to normal levels for approximately 24 h. This performance was better than that obtained with pure ß-glucan from barley, which decreased blood sugar levels for about 4 h. These results suggest that the activity of ß-glucans from R. repens is responsible for the use of this plant extract as a hypoglycemic drug in folk medicine.

Effects of strain and age on ear wound healing and regeneration in mice

Round holes in the ears of MRL mice tend to close with characteristics of regeneration believed to be absent in other mouse strains (e.g., C57BL/6). We evaluated the kinetics and the histopathology of ear wound closure in young (8 weeks old) C57BL/6 and BALB/c mice. We also used middle-aged (40 weeks old) C57BL/6 mice to evaluate the influence of aging on this process. A circular through-and-through hole was made in the ear, photographs were taken at different times after injury and wound area was measured with digital analysis software. The percentages of closed area measured on day 100 were: 23.57 ± 8.66% for young BALB/c mice, 56.47 ± 7.39% for young C57BL/6 mice, and 75.31 ± 23.65% for middle-aged C57BL/6 mice. Mice were sacrificed on days 1, 3, 5, 25, 44, and 100 for histological evaluation with hematoxylin and eosin, Gomori’s trichrome, periodic acid-Schiff, or picrosirius red staining. In young mice of both strains, healing included re-epithelialization, chondrogenesis, myogenesis, and collagen deposition. Young C57BL/6 and BALB/c mice differed in the organization of collagen fibers visualized using picrosirius-polarization. Sebaceous glands and hair follicles regenerated and chondrogenesis was greater in young C57BL/6 mice. In middle-aged C57BL/6 mice all aspects of regeneration were depressed. The characteristics of regeneration were present during ear wound healing in both young BALB/c and young C57BL/6 mice although they differed in intensity and pattern. Greater ear wound closure in middle-aged C57BL/6 mice was not correlated with regeneration.