Detection and transmission of Drechslera avenae from oat seed

Detection, symptoms and symptomless transmission of Drechslera avenae (teleomorph Pyrenophora avenae) from seed were investigated. The present study reported that the D. avenae is frequently found in oat (Avena sativa) seed in Argentina. The prevalence of the seed lot infected was 54%. The incidence of seeds infected by D. avenae in the various seed lots from different regions ranged from 0 to 52% (overall mean of 7%). Besides conidia on conidiophore and immature pseudothecia, D. avenae produced small, spherical to pear-shape picnidia containing tiny conidia, on the seed surface. The pathogen was efficiently transmitted at a rate of 55% from seed to coleoptile tips in symptomless seedlings and at 12.5% to plumules. The importance of the infected seed and its epidemiological role are discussed.

Detection, transmission, pathogenicity and chemical treatment of fungi in Ceiba speciosa seeds

The aim of this work was to evaluate fungus association, transmission and pathogenicity, besides chemical seed treatment in Ceiba speciosa seeds from different regions of southern Brazil. Seven seed samples were used to do the germination test, fungus detection by blotter test and potato-dextrose-agar (PDA), fungus transmission and pathogenicity tests; besides, chemical seed treatments were tested. Germination ranged from 0 to 59,5%. The following fungi were associated in the seeds: Fusarium sp., Alternaria sp., Colletotrichum sp., Curvularia sp. and Pestalotia sp.; in addition, Fusarium sp. was found in all the samples. Alternaria sp. and Fusarium sp. were transmitted by seeds. The isolates of Alternaria sp., Colletotrichum sp. and Fusarium sp., were pathogenic to seedlings and seeds. The seed treatment with methyl tiophanate and the combination captan + methyl tiophanate reduced Fusarium sp. incidence.

Varieties of the generality constraint

Since its introduction by Evans (1982), the generality constraint (GC) has been invoked by various philosophers for different purposes. Our purpose here is, first, to clarify what precisely the GC states by way of an interpretive framework, the GC Schema, and second, to demonstrate in terms of this framework some problems that arise if one invokes the GC (or systematicity) without clearly specifying an appropriate interpretation. By utilizing the GC Schema these sorts of problems can be avoided, and we thus propose it as a tool to facilitate argumentation that appeals to the GC.

Transmission of porcine circovirus 2 (PCV2) by semen and viral distribution in different piglet tissues

Porcine circovirus infections are caused by the porcine circovirus 2 (PCV2). Among six different clinical manifestations involving respiratory, enteric, nervous and reproductive signs, the postweaning multisystemic wasting syndrome (PMWS) is the most important and studied disease. However, reproductive failures associated with PCV2 have been increasingly reported. Some studies have shown the possible contamination of sows by semen of PCV2 positive boars. In order to investigate the transmission of PCV2 by contaminated semen and its ability to infect the sow and piglets, 20 PCV2 negative sows were inseminated, 10 with negative boar semen and 10 with previously nested-PCR tested positive boar semen. The sows were weekly monitored and blood samples were collected. Based on the results, 4 out 20 sows were selected (1 sow was PCR negative and inseminated with a negative semen, 2 sows were PCR negative and inseminated with a positive semen and 1 sow was PCR negative and inseminated with a positive semen, but became PCR positive around the 30 days of pregnancy). After weaning, 12 male piglets, 3 of each sow, were selected and maintained under isolation. In order to investigate which organs harbored the virus, the young pigs were necropsied around 9 months of age. Samples of serum collected monthly were tested by immunocitochemistry (ICC), and all 12 pigs serum converted. Samples of lymphoid, systemic and reproductive organs were analyzed by nested-PCR and immunohistochemistry (IHC). Evaluation of the samples by nested-PCR, revealed that several tissues were positive in 10 of 12 pigs, mainly the lymph nodes, bone marrow and spleen. Various samples were positive by IHC in 8 of 12 piglets, being the lymph nodes, tonsils and bulbourethral glands the most frequently positive. Thus, the results of testing different samples, in the 3 tests (ICC, nested-PCR and IHC) were complementary. These results show that PCV2 transmission through semen to the sows and piglets may occur and may also represent a potential risk for the herd.

Occurrence of infection with Toxoplasma gondii and factors associated with transmission in broiler chickens and laying hens in different raising systems

Toxoplasmosis is a zoonotic disease caused by the protozoan Toxoplasma gondii. The aim of the present study was to determine the occurrence and identify the risk factors associated with transmission of T. gondii to chickens raised in different systems (free-ranged and confined) to produce eggs or meat. The 810 animals were allocated in two experimental groups according to the production system purpose: 460 broiler chickens (Group 1) and 350 layer chickens (Group 2). In order to analyze the possible factors involved in T. gondii infection in the chickens, an epidemiological questionnaire was developed for all properties.The serological detection of anti-Toxoplasma gondii antibodies was performed by Indirect Immunofluorescence (IFAT) and by Enzime Linked Imunossorbent Assay (ELISA). Since the agreement index (kappa) between these two serological techniques was considered high, 21.2% of the 810 animals were considered reactive. In Group 1, 12.2% (56/460) were positive, while in the Group 2 the positivity rate was 33.1% (116/350). The production system may be influencing the seropositivity of the animals in both groups. However, only in Group 2 it was possible to notice a statistically significant relationship between the breeding system and the frequency of positive sera. This result indicates that, at least for laying hens, the production system is directly involved in T. gondii infection. The contact with cats in Group 1 did not influence the distribution of seroreactive animals, but in Group 2 a significant relationship was observed. The occurrence of anti-T. gondii antibodies was high in both groups (broiler and posture chickens). Free-ranged chickens raised for egg production proved to be the most exposed group to the T. gondii infection. This can be related to the fact that these animals stay for longer periods in the farms, in direct contact with possibly contaminated soil by the presence of domestic cats.

Glutamatergic transmission in the nucleus tractus solitarii: from server to peripherals in the cardiovascular information superhighway

Afferent nerves carrying signals from mechanoreceptors in the aortic arch and carotid sinus terminate predominantly in the nucleus tractus solitarii (NTS). Signal transduction and neurotransmission in the NTS are critical for central cardiovascular reflex control, but little was known about either until the late 1970's. None of the numerous neuroactive chemicals found in the NTS had met strict criteria as a neurotransmitter in the baroreflex arc until data suggested that the excitatory amino acid L-glutamate (GLU) might be released from baroreceptor afferent terminals in the NTS. In anesthetized animals microinjection into the NTS of GLU, which can be demonstrated in terminals in the NTS, produces cardiovascular responses like those seen with activation of the baroreceptor reflex. Similar responses occur in awake animals if the chemoreceptor reflex is eliminated; otherwise, in conscious animals responses mimic those of chemoreceptor reflex activation. GLU is released in the NTS upon selective activation of the baroreceptor, and possibly the chemoreceptor, reflex. Responses to selective agonists as well as baroreflex responses are eliminated by GLU antagonists microinjected into the NTS. Non-NMDA (N-methyl-D-aspartic acid) receptors seem to predominate at primary baroreceptor synapses in the NTS while NMDA receptors may be involved at later synapses. Although inhibition of soluble guanylate cyclase attenuates responses to ionotropic glutamate agonists in the NTS, nitric oxide does not seem to play a role in glutamate transmission in the NTS. GLU may also participate in transmission at cardiovascular neurons beyond the NTS. For example, a role has been suggested for GLU in the ventrolateral medulla and spinal cord. Work continues concerning GLU signal transduction and mechanisms that modulate that transduction both at the NTS and at other cardiovascular nuclei

One hundred million years of interhemispheric communication: the history of the corpus callosum

Analysis of regional corpus callosum fiber composition reveals that callosal regions connecting primary and secondary sensory areas tend to have higher proportions of coarse-diameter, highly myelinated fibers than callosal regions connecting so-called higher-order areas. This suggests that in primary/secondary sensory areas there are strong timing constraints for interhemispheric communication, which may be related to the process of midline fusion of the two sensory hemifields across the hemispheres. We postulate that the evolutionary origin of the corpus callosum in placental mammals is related to the mechanism of midline fusion in the sensory cortices, which only in mammals receive a topographically organized representation of the sensory surfaces. The early corpus callosum may have also served as a substrate for growth of fibers connecting higher-order areas, which possibly participated in the propagation of neuronal ensembles of synchronized activity between the hemispheres. However, as brains became much larger, the increasingly longer interhemispheric distance may have worked as a constraint for efficient callosal transmission. Callosal fiber composition tends to be quite uniform across species with different brain sizes, suggesting that the delay in callosal transmission is longer in bigger brains. There is only a small subset of large-diameter callosal fibers whose size increases with increasing interhemispheric distance. These limitations in interhemispheric connectivity may have favored the development of brain lateralization in some species like humans. "...if the currently received statements are correct, the appearance of the corpus callosum in the placental mammals is the greatest and most sudden modification exhibited by the brain in the whole series of vertebrated animals..." T.H. Huxley (1).

The pharmacological effect of Bothrops neuwiedii pauloensis (jararaca-pintada) snake venom on avian neuromuscular transmission

The neuromuscular effects of Bothrops neuwiedii pauloensis (jararaca-pintada) venom were studied on isolated chick biventer cervicis nerve-muscle preparations. Venom concentrations of 5-50 µg/ml produced an initial inhibition and a secondary increase of indirectly evoked twitches followed by a progressive concentration-dependent and irreversible neuromuscular blockade. At venom concentrations of 1-20 µg/ml, the responses to 13.4 mM KCl were inhibited whereas those to 110 µM acetylcholine alone and cumulative concentrations of 1 µM to 10 mM were unaffected. At venom concentrations higher than 50 µg/ml, there was pronounced muscle contracture with inhibition of the responses to acetylcholine, KCl and direct stimulation. At 20-24ºC, the venom (50 µg/ml) produced only partial neuromuscular blockade (30.7 ± 8.0%, N = 3) after 120 min and the initial inhibition and the secondary increase of the twitch responses caused by the venom were prolonged and pronounced and the response to KCl was unchanged. These results indicate that B.n. pauloensis venom is neurotoxic, acting primarily at presynaptic sites, and that enzyme activity may be involved in this pharmacological action.

Risk of hepatitis B virus transmission by diagnostic hysteroscopy

Few data are available in the literature concerning the efficacy of standard hysteroscope disinfection procedures to prevent hepatitis B transmission. The aim of the present study was to determine the risk of hepatitis B virus (HBV) transmission during hysteroscopy among anti-HBc-seropositive women. Serum and hysteroscopic samples were collected from 62 women after diagnostic hysteroscopy. All samples were tested for serologic HBV markers. Polymerase chain reactions (PCR) were carried out to amplify regions C and S of the viral genome and only samples amplified by both pairs of primers were considered to be positive. Anti-HBc was repeatedly reactive in 48 (77%) of 62 serum samples, and HBsAg was detected in 8 (13%). At least one HBV serologic marker was found in 49 (79%) samples. Only one sample was HBsAg positive and anti-HBc negative. HBV-DNA was detected by PCR in 7 serum samples but in only 3 hysteroscopic samples obtained just after hysteroscopy. It is noteworthy that high levels of anti-HBc IgM were detected in one HBsAg-negative patient who showed an HBV-DNA-positive hysteroscopic sample. An elevated sample/cut-off ratio for anti-HBc IgM suggests recent infection and reinforces the need for testing for HBsAg and anti-HBc before hysteroscopy, since acute hepatitis B can be clinically asymptomatic. Viral DNA was not detected in any hysteroscopic samples collected after washing and disinfecting procedures with glutaraldehyde. We conclude that HBV-DNA can be found in the hysteroscope soon after hysteroscopy, but standard disinfecting procedures are effective in viral removal.

Cross-transmission of vancomycin-resistant Enterococcus in patients undergoing dialysis and kidney transplant

The objective of this study was to investigate the occurrence of vancomycin-resistant Enterococcus (VRE) cross-transmission between two patient groups (long-term dialysis and kidney transplant patients). Molecular typing, by automated ribotyping with the RiboPrinter Microbial Characterization System (Qualicon, USA), was used to analyze VRE isolates from 31 fecal samples of 320 dialysis patients and 38 fecal samples of 280 kidney transplant patients. Clonal spread of E. faecalis and E. casseliflavus was observed intragroup, but not between the two groups of patients. In turn, transmission of E. gallinarum and E. faecium between the groups was suggested by the finding of vancomycin-resistant isolates belonging to the same ribogroup in both dialysis and transplant patients. The fact that these patients were colonized by VRE from the same ribogroup in the same health care facility provides evidence for cross-transmission and supports the adoption of stringent infection control measures to prevent dissemination of these bacteria.

Three days of intermittent stretching after muscle disuse alters the proteins involved in force transmission in muscle fibers in weanling rats

The aim of this study was to determine the effects of intermittent passive manual stretching on various proteins involved in force transmission in skeletal muscle. Female Wistar weanling rats were randomly assigned to 5 groups: 2 control groups containing 21- and 30-day-old rats that received neither immobilization nor stretching, and 3 test groups that received 1) passive stretching over 3 days, 2) immobilization for 7 days and then passive stretching over 3 days, or 3) immobilization for 7 days. Maximal plantar flexion in the right hind limb was imposed, and the stretching protocol of 10 repetitions of 30 s stretches was applied. The soleus muscles were harvested and processed for HE and picrosirius staining; immunohistochemical analysis of collagen types I, III, IV, desmin, and vimentin; and immunofluorescence labeling of dystrophin and CD68. The numbers of desmin- and vimentin-positive cells were significantly decreased compared with those in the control following immobilization, regardless of whether stretching was applied (P<0.05). In addition, the semi-quantitative analysis showed that collagen type I was increased and type IV was decreased in the immobilized animals, regardless of whether the stretching protocol was applied. In conclusion, the largest changes in response to stretching were observed in muscles that had been previously immobilized, and the stretching protocol applied here did not mitigate the immobilization-induced muscle changes. Muscle disuse adversely affected several proteins involved in the transmission of forces between the intracellular and extracellular compartments. Thus, the 3-day rehabilitation period tested here did not provide sufficient time for the muscles to recover from the disuse maladaptations in animals undergoing postnatal development.

Detection, transmission and pathogenicity of fungi on Blepharocalyx salicifolius (H.B.K.) Berg. seeds

The objective of this study was to identify the fungi associated with the fruit and seeds of Blepharocalyx salicifolius and verify their transmission and pathogenicity to seeds and seedlings. Fungal identification on seeds was made using the blotter test and potato-dextrose-agar but only the blotter test was used for fruit. Fungal transmission to seedlings was evaluated using four replications of 50 seeds planted in vermiculite. The pathogenicity of the fungi, Colletotrichum sp., Curvularia sp., Cladosporium sp. Pestalotia sp. and Macrophomina sp. was tested. Potentially pathogenic and saprophytic fungi were found on the fruits and seeds. The transmission of Cladosporium sp. from seeds to seedlings was verified, and Cladosporium sp. Pestalotia sp. and Macrophomina sp. were found to be pathogenic to B. salicifolius seedlings.