ULTRASTRUCTURAL SIMILARITY BETWEEN BAT AND HUMAN MAST-CELL SECRETORY GRANULES

Mast cells in the tongue of the bat (Artibeus lituratus) show a well-developed Golgi area and abundant mitochondria in the granule-free perinuclear cytoplasm. Rough endoplasmic reticulum profiles, free ribosomes, mitochondria, bundles of filaments and a great number of secretory granules are found throughout the remaining cytoplasm. The granules, of various shapes and sizes, are simple containing an electron-dense, homogeneous matrix, coarse particles or cylindrical scrolls, or combinations (cylindrical scrolls with either electron-dense, homogeneous matrix or coarse particle contents). Up to now, scroll-containing granules have been considered to be a unique feature of human mast cells.

Mast cells in the eyes of Calomys callosus (Rodentia : Cricetidae) infected by Toxoplasma gondii

The mast cell is a powerful effector cell for the innate immune system, acting through the secretion of several distinct mediators. Few studies have demonstrated the relationship between mast cells and toxoplasmosis. In this study, mast cells were investigated in two experimental Toxoplasma infections using Calomys callosus (Rodentia: Cricetidae) as the host. Animals were inoculated either intraperitoneally or via the conjunctiva with tachyzoites of Toxoplasma gondii (RH strain) and sacrificed after 5 days or 24 h, respectively. Enucleated eyes were processed for histological and ultrastructural analysis. Neither experimental infection altered the localization of mast cells compared to control eyes, but they did lead to an accumulation in some tissues as well as to their activation. There was a significant increase in the number of mast cells within 5 days and 24 h after infection. The ocular lesions were characterized by the presence of tachyzoites, inflammatory cells and vasodilatation in the iris and retina. In conclusion, mast cells were mobilized in these experimental infections, suggesting that they play an important role in the host inflammatory response after infection with T. gondii.

Immunohistochemical evaluation of prostaglandin E2 and vascular endothelial growth factor in canine cutaneous mast cell tumours

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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.

Gap junctions between mast cells and fibroblasts in the developing avian eye

Mast cells are present in the eye of chick embryos from the 14th day onward, displaying metachromatic granules, mainly in the iris anterior surface and pectinate ligament. Ultrastructurally these cells show electron-dense granules and a few thin and short cytoplasmic projections in close contact with fibroblasts. Sometimes these contacts are extensive, with long fibroblast projections partially involving the mast cells. Gap junctions between mast cells and fibroblasts are observed only in the eyes of 16- and 20-day-old embryos. These intercellular specializations are represented by a close apposition of cytoplasmic membranes with an extension up to 300 nm. Gap junctions between mast cells and fibroblasts were not observed previously in vivo or in vitro, although in vitro studies have shown that a number of functionally critical interactions may occur between these cells. Our morphological findings suggest that, in vivo, fibroblasts interact with mast cells and may influence their maturation.

Characteristics of the histamine release from hamster cheek pouch mast cells stimulated by lectins from Brazilian beans and concanavalin A

We have characterized the histamine releasing effects of lectins extracted from Brazilian beans, in comparison to concanavalin A, in hamster cheek pouch cell suspensions containing mast cells. The lectins from Dioclea virgata, Canavalia brasiliensis, and Dioclea rostrata induce histamine release in a similar manner to concanavalin A, but appear to differ in potency and efficacy. The effects depended on the temperature, pH, and metabolic energy, demonstrating the non-cytotoxic nature of the histamine release. It is suggested that the lectins studied act by the same mechanism as concanavalin A (interacting with sugars in the antibodies bound to the mast cells), since high concentrations of glucose inhibit the histamine release. The lectins at high concentrations quench the histamine release. This suppression is reversed by increasing calcium concentration, suggesting that the lectins bind to the calcium that is essential for the secretion, thereby confirming and extending our previous data using the lectin from Dioclea virgata in rat peritoneal mast cells.

Characterization of a monoclonal antibody recognizing mast cells

Immunohistochemical screening for monoclonal antibodies prepared by immunization of mice with a rat osteoblastic cell population led to identification of one antibody that reacted against a small population of cells present in the soft connective tissue compartment of 21 days fetal rat calvaria. The morphology of the cells and the immunohistochemical staining characteristics (a distinct intracellular granular pattern) suggested that the antibody might be reacting specifically against mast cells. We used combined histochemistry and immunohistochemistry to further characterize this antibody, designated RCJ102. Cryosections containing calvaria bone, soft connective tissues and skin were prepared from the top of the head of 21 days fetal rats, and from adult rats cryosections of lung, muscle, adipose tissue and small intestine were prepared. Some sections were labelled by indirect immunofluorescence with RCJ102; corresponding sections were labelled histochemically with toluidine blue. There was a direct correspondence between mast cells identified histochemically and cells labelling with RCJ102 in all tissues except intestine, in which the mast cell detectable by histochemistry were not labelled by RCJ102. These results suggest that the RCJ102 antibody will be a valuable new reagent for further elucidation of the heterogeneity described between connective tissue and intestinal mucosal mast cells.

Peritoneal effusion in a dog secondary to visceral mast cell tumor: A case report

BACKGROUND: Mast cell tumor, one of the most common skin tumors in dogs, may also be found in visceral sites (mainly spleen and liver). When a visceral mast cell tumor is present, neoplastic mast cells may be found in any effusion secondary to the tumor. Therefore, the diagnosis may be made by cytologic analysis of the effusion. CASE: An 8-year-old, spayed, female Siberian husky presented with a peritoneal effusion secondary to a visceral mast cell tumor. Seven months earlier, the dog had presented with a cutaneous nodule diagnosed as a well-differentiated mast cell tumor. The peritoneal fluid was classified as a transudate. Numerous neoplastic mast cells were found in the effusion. Although the mast cell tumor presented with characteristics of the well-differentiated tumor, its biologic behavior was that of a malignant tumor. CONCLUSION: Care should be taken to evaluate the prognosis of mast cell tumors in dogs since their biologic behavior is extremely variable.

Visceral mast cell tumor in a captive black jaguar (Panthera onca)

Little is known about neoplasia in the jaguar (Panthera onca), the largest American feline. A captive black jaguar was diagnosed at necropsy with a mastocytic form of visceral mast cell tumor similar to that which occurs in domestic cats. This animal had no previous clinical disease and died during anesthesia for a routine dental treatment.

Efeito da sacarose e sorbitol na conservação in vitro de Passiflora giberti N. E. Brown

This work objectified the study of sucrose and sorbitol effect in the in vitro conservation for Passiflora giberti N. E. Brown, access. Therefore, an experiment was conducted in a completely randomized design to compare control treatment (standard MS) to MS medium supplemented with three sucrose concentrations (0, 15 and 30 g L -1) combined with three sorbitol concentrations (10, 20 and 40 g L -1), in a total of 10 treatments with 20 replicas. The experiment evaluation was carried out at 30, 60, 90 and 120 days of incubation, whereas the height of shoots (cm), number of roots, number and color of leaves were observed. The results showed the possibility to maintain passion-fruit microplants for a four months period under slow growth in MS medium supplemented with 10 or 20 g L -1 of sorbitol, without sucrose, and kept under 16 hours photoperiod (22 μ E m -2 s -1) and temperature of 27 ± 1°C. Sucrose sustained the longest development of the microplants. Root formation was affected by the sorbitol in the concentration of 40 g L -1 and by the absence of sucrose in the culture medium.

Neutrophil migration induced by IL-1β depends upon LTB4 released by macrophages and upon TNF-α and IL-1β released by mast cells

In the present study, we investigate whether mast cells and macrophages are involved in the control of IL-1β-induced neutrophil migration, as well as the participation of chemotactic mediators. IL-1β induced a dose-dependent neutrophil migration to the peritoneal cavity of rats which depends on LTB 4, PAF and cytokines, since the animal treatment with inhibitors of these mediators (MK 886, PCA 4248 and dexamethasone respectively) inhibited IL-1β-induced neutrophil migration. The neutrophil migration induced by IL-1β is dependent on mast cells and macrophages, since depletion of mast cells reduced the process whereas the increase of macrophage population enhanced the migration. Moreover, mast cells or macrophages stimulated with IL-1β released a neutrophil chemotactic factor, which mimicked the neutrophil migration induced by IL-1β. The chemotactic activity of the supernatant of IL-1β-stimulated macrophages is due to the presence of LTB4, since MK 886 inhibited its release. Moreover, the chemotactic activity of IL-1β-stimulated mast cells supernatant is due to the presence of IL-1β and TNF-α, since antibodies against these cytokines inhibited its activity. Furthermore, significant amounts of these cytokines were detected in the supernatant. In conclusion, our results suggest that neutrophil migration induced by IL-1β depends upon LTB4 released by macrophages and upon IL-1β and TNFα released by mast cells. © 2007 Springer Science+Business Media, LLC.

Cytoplasmic and nuclear morphometric parameters in cytologic preparations of canine cutaneous mast cell tumors

Thirty fine-needle biopsy (FNB) samples from 28 dogs subjected to surgical resection of cutaneous mast cell tumors (MCTs) were stained with Giemsa. At least 100 neoplastic cells from each cytology slide were evaluated by morphometric analysis. The parameters were: area, perimeter of the cell, cytoplasm, nucleus and circumference factor. MCTs of grade III had a mean cellular area of 231.70 μm2 ± 57.1, and grade II had a mean of 252.30 μm2 ± 55.0. Cellular perimeter was 61.20 ± 7.1 in grade II and 59.1 ± 8.6 in grade III. Cellular parameters were not statistically different between grades (p>.05). Mean nuclear area was 88.90 μm2 ± 19 in grade III and 72.30 μm2 ± 13.9 in grade II, with statistical difference between grades (P =.011). Mean nuclear perimeter was 32.40 ìm ± 3.0 in grade II and 35.70 ìm ± 4.0 in grade III, with statistical difference between grades (P =.018). Mean nuclear circumference factor was 1.0 ± 0.33 in grade II and 1.1 ± 0.28 in grade III, with no statistical difference between grades (P = 0.78). Nuclear-tocytoplasmic ratio in grade II was 0.29 ±.07 and 0.39 ±.08 in grade III, with statistical difference (P =.02). The number of binucleated and multinucleated cells and mitotic figures was significantly increased in grade III MCTs (P <.001). In conclusion, the number of mitotic figures, presence of binucleation and multinucleation, and nuclear-to-cytoplasmic ratio can help to guide a profile of MCT aggressiveness in cytologic preparations.

Mast cells modulate the inflammatory process in endotoxin-induced uveitis

Purpose: To investigate the role of mast cells and annexin-A1 (Anxa1) in endotoxin-induced uveitis (EIU). Methods: EIU was induced by injection of lipopolysaccharide (LPS) into the paws of rats, which were then sacrificed after 24 and 48 h. To assess EIU in the absence of mast cells, groups of animals were pretreated with compound 48/80 (c48/80) and sacrificed after 24 h after no treatment or EIU induction. The eyes were used for histological studies and the aqueous humor (AqH) pool was used for the analysis of transmigrated cells and Anxa1 levels. In inflammatory cells, Anxa1 expression was monitored by immunohistochemistry. Results: After 24 h, rats with EIU exhibited degranulated mast cells, associated with elevated numbers of infiltrating leukocytes and the high expression of Anxa1 in the AqH and the neutrophils. After 48 h of EIU, the mast cells were intact, indicating granule re-synthesis, and there was a reduction of neutrophil transmigration and an increase in the number of mononuclear phagocytic cells in ocular tissues. Anxa1 expression was decreased in neutrophils but increased in mononuclear phagocytic cells. In the animals pretreated with c48/80 and subjected to EIU, mast cells responded to this secretagogue by degranulating and few transmigrated neutrophils were observed. Conclustions: We report that mast cells are a potential source of pharmacological mediators that are strongly linked to the pathophysiology of EIU, and the endogenous protein Anxa1 is a mediator in the homeostasis of the inflammatory process with anti-migratory effects on leukocytes, which supports further studies of this protein as an innovative therapy for uveitis. © 2011 Molecular Vision.