Meiotic nucleolar cycle and chromatoid body formation during the rat (Rattus novergicus) and mouse (Mus musculus) spermiogenesis

The aims of the present study were to follow the nucleolar cycle in spermiogenesis of the laboratory rodents Rattus novergicus and Mus musculus, to verify the relationship between the nucleolar component and chromatoid body (CB) formation and to investigate the function of this cytoplasmic supramolecular structure in spermatogenic haploid cells. Histological sections of adult seminiferous tubules were analyzed cytochemically by light microscopy and ultrastructural procedures by transmission electron microscopy. The results reveal that in early spermatids, the CB was visualized in association with the Golgi cisterns indicating that this structure may participate in the acrosome formation process. In late spermatids, the CB was observed near the axonema, a fact suggesting that this structure may support the formation of the spermatozoon tail. In conclusion, our data showed that there is disintegration of spermatid nucleoli at the beginning of spermatogenesis and a fraction of this nucleolar material migrates to the cytoplasm, where a specific structure is formed, known as the "chromatoid body", which, apparently, participates in some parts of the rodent spermiogenesis process. (c) 2007 Elsevier Ltd. All rights reserved.

An essential role for mast cells as modulators of neutrophils influx in collagen-induced arthritis in the mouse

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

Biocompatibility of a chlorhexidine local delivery system in a subcutaneous mouse model

Objective: This study aimed evaluating histologically and histomorphometrically the response of the conjunctive tissue face to the implant of chlorhexidine chips in the subcutaneous tissues of rats. Study Design: In this research 35 male rats Wistar were used to analyze the biocompatibility and the degradation process of chlorhexidine chip. In each animal, it was made 2 incisions for subcutaneous implantation of chlorhexidine chip (test group) and a polytetrafluorethylene membrane (control group). The morphological changes in subcutaneous implantations were assessed after 1, 3, 5, 7, 10, 14, 21 days. The data were submitted to Friedman nonparametric test to analyze the comparisons among observation periods and to allow the comparison among groups. Results: Differences were found in the analysis of the inflammatory response when comparing the tested materials (p values <= 0.05). In test group was observed hemorrhage, edema and intense inflammatory infiltrate predominantly neutrophilic around material. From 3-day and subsequent periods was verified granulation tissue externally at this infiltrate. From 10-day on was observed crescent area of degradation of chlorhexidine chip, associated with neutrophilic and macrophagic infiltrate, that maintained until 21-day. In the control group, moderate inflammatory infiltrate was observed initially, predominantly polymorphonuclear, edema and granulation tissue 3-day period. The inflammatory infiltrate was gradually replaced for granulation tissue, culminating in a fibrous capsule. Giant multinucleate cells situated at contact interface with the coating was examined since 3-day and persisted until 21-day. Conclusion: The chlorhexidine chip induces an intense acute inflammatory response at subcutaneous tissue of rats. Therefore, at conditions of this study was not biocompatible.

Rabies laboratory diagnosis: peculiar features of samples from equine origin

O diagnóstico laboratorial da raiva é realizado através de métodos de pesquisa do corpúsculo de Negri, imunofluorescência direta e inoculação em camundongos. Na maioria dos casos, quando a amostra é bem coletada, bem conservada e o profissional responsável possui experiência, verifica-se concordância entre as técnicas utilizadas. A Seção de Raiva e Encefalomielite do Instituto Biológico ao comparar a sensibilidade das três técnicas diagnósticas, em 3713 amostras (córtex cerebral, cerebelo e hipocampo) recebidas no período de 1980-1994, sendo 3010 da espécie bovina (983 positivas) e 703 da espécie eqüina (111 positivas), observou que, no caso da raiva eqüina, esta concordância não é mantida. Verificou-se, nesta espécie, que somente em algumas oportunidades foi possível identificar, pelo método histopatológico, o corpúsculo de Negri. em relação à prova de imunofluorescência pode-se afirmar que a mesma detectou uma porcentagem menor de amostras positivas, provenientes da espécie equina, em compração com as da espécie bovina, sendo esta diferença estatisticamente significativa. A prova biológica foi a mais sensível, porém houve uma diferença, também significativa, entre o período de incubação em camundongos das amostras de origem bovina e das de origem eqüina. A presença pouco frequente de corpúsculos de Negri e o período de incubação em camundongos mais prolongado, das amostras de origem eqüina, sugerem que devem ser intensificados os estudos da patogenia da raiva nesta espécie.

Multiplex polymerase chain reaction to identify and determine the toxigenicity of Corynebacterium spp with zoonotic potential and an overview of human and animal infections

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Intoxicação experimental de bovinos com toxina botulínica tipo D

Realizou-se uma intoxicação experimental em bovinos, pela administração oral, com diferentes doses de toxina botulínica tipo D. O objetivo foi determinar o tempo de permanência da toxina no sangue circulante de bovinos, pela detecção da toxina no soro mediante bioensaio em camundongos, e de verificar a presença da toxina no fígado, no baço, nos rins e no coração, e no conteúdo ruminal de bovinos que morreram e/ou foram sacrificados. Utilizaram-se 12 bovinos, mestiços, divididos em quatro grupos de três animais cada. Os grupos I, II e III receberam 200DL50/ml, 21.300DL50/ml e 63.200DL50/ml de toxina botulínica, respectivamente, e o grupo IV manteve-se como controle. A toxina foi detectada principalmente no soro dos bovinos pertencentes aos grupos II e III que receberam altas doses do inóculo tóxico, nos quais a toxina permaneceu por um período de um a sete dias após o aparecimento dos primeiros sinais clínicos da doença. A toxina não foi detectada no fígado, no baço, nos rins e no coração, mas o foi no conteúdo ruminal de um bovino do grupo II. A toxina botulínica foi mais facilmente detectada no soro do que nos órgãos dos bovinos, sendo encontrada principalmente quando o animal ingeriu muita toxina, durante a fase inicial da doença e por um período de sete dias.

Antigenic typing of brazilian rabies virus samples isolated from animals and humans, 1989-2000

Amostras de vírus rábico isoladas de animais e humanos no período de 1989 a 2000 foram tipificadas antigenicamente com a utilização de um painel de anticorpos monoclonais contra a nucleoproteína viral, pré-estabelecido para o estudo da epidemiologia molecular do vírus rábico isolado nas Américas. As amostras testadas foram isoladas no laboratório de diagnóstico do Instituto Pasteur e outros centros de diagnóstico de raiva no Brasil. Além das cepas de vírus rábico fixo CVS-31/96-IP, mantida em cérebro de camundongos e a PV-BHK/97, mantida em cultura de células, cepas de vírus rábico isoladas de cães, gatos, bovinos, eqüinos, morcegos, ovinos, caprino, suínos, raposa, sagüí, coatí, guaxinim e humanos, totalizaram 330 amostras. Seis variantes antigênicas foram definidas, compatíveis com perfís observados no painel de anticorpos monoclonais pré-estabelecido utilizado, as de número 2 (cão), 3 (Desmodus rotundus), 4 (Tadarida brasiliensis), 5 (Vampiro da Venezuela), 6 (Lasiurus cinereus) e Lab (reagente a todos os anticorpos utilizados), além de outros seis perfís desconhecidos, não compatíveis com aqueles observados no painel utilizado. A maior variabilidade foi observada entre as amostras isoladas de morcegos insetívoros e a variante mais comum isolada entre as espécies foi a variante 3 (Desmodus rotundus). Estes fatos podem representar a existência de múltiplos ciclos de transmissão independentes, envolvendo diferentes espécies de morcegos.

Influence of cholecalciferol (Vitamin D3) on the course of experimental systemic lupus erythematosus in F1 (NZBxW) mice

The course of systemic lupus erythematosus (SLE), an autoimmune disease, is markedly affected by hormones such as estrogen and prolactin. It is well known that heavy exposure to sunlight has deleterious effects on SLE, triggering episodes of the disease. Classical explanations for this occurrence suggest that UV radiation damages DNA, which becomes immunogenic, or induces exposure of the Ro antigen in keratinocytes. In recent years, it has been shown that vitamin D3 has important effects on the immune system. Thus, we proposed an alternative hypothesis, suggesting that UV radiation, by promoting vitamin D3 synthesis, could be a factor aggravating the course of SLE after exposure to sunlight. To test this hypothesis, we injected F1(NZBxW) mice, which are prone to developing SLE, with vitamin D3, and we demonstrated a worsening of the histopathological findings in the kidney. (C) 2000 Wiley-Liss, Inc.

Mouse extensor digitorum longus and soleus show distinctive ultrastructural changes induced by veratrine

We investigated whether veratrine (5 μl, 10 ng/kg) injected into the mouse extensor digitorum longus (EDL) (fast-twitch) and soleus (SOL) (slow-twitch) muscles provokes distinctive ultrastructural disturbances 15, 30 and 60 min later. The mitochondria in SOL were affected earlier (within 15 min) than in EDL. Swelling of the sarcoplasmic reticulum terminal cisternae was more marked in EDL than in SOL and caused distortion of sarcomeres so that fragmentation of myofilaments was more pronounced in EDL. Hypercontracted sarcomeres were seen mainly in SOL and veratrine caused infoldings of the sarcolemma only in this muscle. In both muscles, the T-tubules remained unaffected and by 60 min after veratrine most of the above alterations had reverted to normal. Pretreatment with tetrodotoxin prevented the alterations induced by veratrine. This suggests that most of the alterations resulted from the enhanced influx of Na+ into muscle fibers. These results emphasize the importance of considering the type of muscle when studying the action of myotoxic agents.

Study on the mutagenicity and antimutagenicity of a natural food colour (annatto) in mouse bone marrow cells

Most manufactured foods contain chemicals added as a deliberate part of the manufacturing process. The aims of the present study were to evaluate the mutagenicity and antimutagenicity of annatto, a natural pigment extracted from the Bixa orellana L. and widely used as a colorant in foods. The micronucleus test was performed in bone marrow cells from Swiss male mice treated with one of the three concentrations of annatto (1330, 5330 and 10,670 ppm), incorporated into the diet. The animals were fed with the diets for 7 days and sacrificed 24 h after the last treatment. For the evaluation of the antimutagenic potential of annatto, at day 7, the animals received an intraperitoneal injection of cyclophosphamide (50 mg/kg body weight). Under the concentrations tested annatto did not present mutagenic or antimutagenic activities on the mice bone marrow cells. However, an increased frequency of micronucleated cells was observed when the highest concentration (10,670 ppm) was administered simultaneously with cyclophosphamide. In conclusion, the data indicate that annatto colour, for the conditions used, is neither mutagenic nor an inhibitor of induced mutations, although it should be used carefully since high doses may increase the effect of a mutagen. © 2003 Elsevier Science Ltd. All rights reserved.

Secretion of tumor necrosis factor-alpha by mouse peritoneal macrophages in the presence of dental sealers, sealapex and endomethasone

After filling root canals, the healing process depends on the chemical composition or physical-chemical properties of the material used, among other factors. All root canal sealers, whether solid or plastic, are foreign matter for the body if they remain in permanent contact with apical and periapical tissues. As a result, the first organic reaction that occurs is an attempt to phagocytize the material. During phagocytosis, macrophages release a large number of cell mediators into the area, among which are cytokines that are essential in intercellular communication and in many physiological and pathophysiological processes. One of these cytokines is tumor necrosis factor-alfa (TNF-α), which acts through links to specific receptors on the cell membrane initiating a cascade of events leading to induction, activation, or inhibition of numerous cytokine-regulated genes in the cell nucleus. The release of TNF-α in a cell culture of mouse peritoneal macrophages incubated with three concentrations (25, 50, and 100 mg/ml) of two endodontic sealers was measured. The solutions containing the calcium hydroxide-based root canal sealer (Sealapex) released fewer units of TNF-α than solutions containing the zinc oxide and eugenol-based sealer (Endomethasone).

Morphometric study of the postnatal growth of the parotid gland of the mouse

The growth of the mouse parotid glands during 7 and 35 days of postnatal life was studied by morphometric methods. The mass of the gland, the volume of each morphological compartment, and the cell number in each compartment were evaluated. The data obtained for each evaluated dimension were adjusted by an exponential equation, of the type Y = a.e KX, thus permitting the calculation of their mean duplication time (T D), i.e., an estimation of their growth rate. Analysis of the results showed a marked 1,424% increase in the gland mass during the whole studied period, with T D = 7.10 days. This growth occurred by increases in absolute volume of acini, intercalated ducts, striated ducts, excretory ducts and stroma, with percentual increases of 3,048%, 417%, 2,662%, 2,594% and 367%, respectively, and T Ds of 5.62, 11.71, 5.55, 5.47 and 14.45 days, respectively. Analysis of the cell number growth in each compartment showed increases of 1,904%, 285%, 1,228%, 1,090% and 286%, respectively, and T Ds of 6.62, 20.40, 7.19, 7.26 and 14.51 days, respectively. Based on the present results, we concluded that the growth of the mouse parotid glands from day 7 to day 35 of age occurred by intense cell accumulation, mainly in the acini, striated ducts and excretory ducts, with a growth rate sensibly higher than that of the intercalated ducts and stroma.

Maxi-K channels contribute to urinary potassium excretion in the ROMK-deficient mouse model of Type II Bartter's syndrome and in adaptation to a high-K diet

Type II Bartter's syndrome is a hereditary hypokalemic renal salt-wasting disorder caused by mutations in the ROMK channel (Kir1.1; Kcnj1), mediating potassium recycling in the thick ascending limb of Henle's loop (TAL) and potassium secretion in the distal tubule and cortical collecting duct (CCT). Newborns with Type II Bartter are transiently hyperkalemic, consistent with loss of ROMK channel function in potassium secretion in distal convoluted tubule and CCT. Yet, these infants rapidly develop persistent hypokalemia owing to increased renal potassium excretion mediated by unknown mechanisms. Here, we used free-flow micropuncture and stationary microperfusion of the late distal tubule to explore the mechanism of renal potassium wasting in the Romk-deficient, Type II Bartter's mouse. We show that potassium absorption in the loop of Henle is reduced in Romk-deficient mice and can account for a significant fraction of renal potassium loss. In addition, we show that iberiotoxin (IBTX)-sensitive, flow-stimulated maxi-K channels account for sustained potassium secretion in the late distal tubule, despite loss of ROMK function. IBTX-sensitive potassium secretion is also increased in high-potassium-adapted wild-type mice. Thus, renal potassium wasting in Type II Bartter is due to both reduced reabsorption in the TAL and K secretion by max-K channels in the late distal tubule. © 2006 International Society of Nephrology.

Toxoplasma gondii: Detection by mouse bioassay, histopathology, and polymerase chain reaction in tissues from experimentally infected pigs

In the present study, we evaluated three techniques, mouse bioassay, histopathology, and polymerase chain reaction (PCR) to detect Toxoplasma gondii infection in tissues from experimentally infected pigs. Twelve mixed breed pigs, seronegative for T. gondii using an indirect immunofluorescent antibody test (IFAT), were used. Ten pigs were infected with 4 × 104 VEG strain oocysts, and two were maintained as uninfected controls. Animals were killed 60 days pos infection. Muscle (heart, tongue, diaphragm, and masseter) and brain samples were collected to investigate the presence of T. gondii tissue cysts by the different assay methods. For the bioassay, samples of brain (50 g) and pool of muscle samples (12.5 g of tongue, masseter, diaphragm, and heart) were used. PCR was performed using Tox4 and Tox5 primers which amplified a 529 bp fragment. The DNA extraction and PCR were performed three times, and all tissue samples were tested individually (brain, tongue, masseter, diaphragm, and heart). For histopathology, fragments of tissues were fixed in 10% of buffered formal saline and stained with HE. Histopathological results were all negative. PCR showed 25/150 (16.6%) positive samples, being 17/120 (14.1%) and 8/30 (26.6%) from muscle, and brain tissues, respectively. Tissue cysts of T. gondii were identified by mouse bioassay in 54/98 (55.1%) samples, being 31/48 (64.6%) from muscle samples, and 23/50 (46.0%) from brain samples. Toxoplasma gondii isolation in muscle samples by mouse bioassay was higher than in PCR (P < 0.01). Results indicate that DNA from pig tissues interfered with 529-bp-PCR sensitivity, and mouse bioassay was better than PCR in detecting T. gondii in tissues from pigs. © 2006 Elsevier Inc. All rights reserved.