Synthesis and fungistatic activity of new groups of 2,4-dihydroxythiobenzoyl derivatives against phytopathogenic fungi

Twenty-six compounds, derivatives of amides, hydrazines, hydrazides, hydrazones, and semicarbazides, with a 2,4-dihydroxythiobenzoyl moiety, were synthesized from sulfinyl-bis(2,4-dihydroxythiobenzoyl). The compositions and chemical structures of these compounds were confirmed by IR, (1)H NMR, EI-MS, and elemental analysis. Antifungal properties of chemicals under in vitro conditions against five phytopathogenic fungi were estimated. In vivo studies against Erisiphe graminis were also carried out. The compounds N-substituted with an 2,4-dihydroxythiobenzamide group proved to be the most active. N-2-(1-Cinnamylbenzene ester)-2,4-dihydroxythiobenzamide, under in vitro conditions, showed activity at the level of 80-100% development of most pathogens at a concentration of 20 microg/mL and partially at a concentration of 200 microg/mL. For compounds with -HN-NH- or -NH-N= moiety, weak or no fungistatic properties were found at the concentrations studied.     

Identification of surface morphologic changes in the mitral valve leaflets and chordae tendineae of dogs with myxomatous degeneration

OBJECTIVE: To describe structural changes in the left atrioventricular (mitral) valve complex of dogs with endocardiosis by use of scanning electron microscopy. ANIMALS: 5 clinically normal dogs and 4 dogs with mitral valve endocardiosis. PROCEDURE: The mitral valve complex from each dog was fixed and prepared for examination via scanning electron microscopy. Findings in valves from clinically normal and affected dogs were compared to identify surface changes associated with endocardiosis. RESULTS: Compared with findings in valves from clinically normal dogs, endocardiosis-affected mitral valve complexes had several morphologic abnormalities. Tissue swelling on the edge of valve leaflets, chordae tendineae, and the chordal-papillary muscle junction was evident. Damage to the valve complex endothelium was unevenly distributed; in some areas, denudation of endothelial cells had exposed the basement membrane or subendothelial valve collagen matrix. This damage was most noticeable on the leaflet edges and extended more to the ventricular aspect of the valve than the atrial side. Cell loss also extended to the chordae tendineae but was less apparent at the chordal-papillary muscle junction. The remaining endothelial cells on affected valves were arranged in less-ordered rows and had more plasmalemmal microappendages, compared with cells on unaffected valves. CONCLUSIONS AND CLINICAL RELEVANCE: Morphologic changes associated with mitral valve endocardiosis in dogs were similar to those observed in humans with mitral valve prolapse. In dogs with mitral valve endocardiosis, gross changes in the valve complex may affect hemodynamics in the heart; alterations in the leaflet and chordal endothelium may contribute to pathogenesis of this disease.     

Infections and some other conditions affecting the skin and subcutis of the naso-ocular region of cats--clinical experience 1987-2003

Infections of the skin or subcutis of the naso-ocular region develop through two mechanisms. Cases with lesions but without concomitant signs of nasal disease probably result from cat scratch injuries. Under certain circumstances, such lacerations result in the introduction of saprophytic microorganisms in such large numbers that host defence mechanisms are overwhelmed. This results in localised, variably invasive, disease in an otherwise immunocompetent host. An unpredictable range of organisms can give rise to such infections including a variety of fungal and bacterial genera. Causal organisms will likely vary from one geography to another as a result of differences in soil type and related environmental factors. Accordingly, procurement of appropriate tissue specimens for culture and susceptibility testing is essential to guide therapy, as these cases require medical and sometimes surgical intervention in order to effect a favourable outcome. In contrast, patients with naso-ocular lesions and concurrent signs of nasal disease have a different pathogenesis. Primary infection of the sinonasal region likely results from the inhalation of infectious propagules, with the infection subsequently penetrating overlying bones to invade the subcutaneous space. These lesions are typically the result of cryptococcosis or aspergillosis and must be distinguished from invasive nasal malignancies. An approach to the investigation and treatment of these patients is presented together with photographs of representative cases.     

Early stages of infection of maize (Zea mays) and Pennisetum setosum roots by the parasitic plant Striga hermonthica

Infection of young roots of maize (Zea mays L.) by the parasitic plant Striga hermonthica (Del.) Benth. was examined. Attachment to and penetration of roots occurred within 1–2 days after inoculation. Subsequent growth through the cortex to the host stele and proliferation of parasite xylem tissue was commonly completed by 3–4 days after inoculation. Histochemical staining showed that young maize roots do not contain major wall-thickening components. However, an increase in cell wall fluorescence and endodermal cell wall thickness was often seen at the site of infection and in the surrounding maize root tissue at 3 days after inoculation. This host response was variable and did not prevent rapid and successful penetration by the parasite. In contrast, uninfected roots of Pennisetum setosum (Sw.) L. Rich., a species resistant to S. hermonthica, had substantial thickening of the inner endodermal cell walls and exhibited further cell wall thickening at the stele upon infection. Examination of infections on both hosts demonstrated the presence of autofluorescent material at the host-parasite interface. This material was thicker and more extensive at the P. setosum-S. hermonthica interface than at the maize-S. hermonthica interface, and contained polyphenols and lignin. Examination of the host-parasite xylem connections in maize revealed substantial invasion of the host stele by both parenchyma and tracheary elements. In a few cases of P. setosum infection, parasite cells entered the stele; however, this did not lead to successful establishment of the parasite.     

Risk factors for bovine tuberculosis in New Zealand cattle farms and their relationship with possum control strategies

This paper reports the investigation of farm-level risk factors for confirmed bovine tuberculosis (TB), based on a retrospective cohort study of a population of cattle in the lower North Island of New Zealand. Data were obtained from the TB testing surveillance programme operational in this area since the mid-1970s and comprised 190,665 cattle-years at risk from July 1980 to June 2004 (inclusive). A mixed-effects Poisson regression model was used to investigate the influence of farm-level covariates on the number of cattle confirmed with TB throughout the study period. This model was interpreted in context of depopulation strategies for the wildlife reservoir for TB, the brushtail possum Trichosurus vulpecula, that were applied in this area. The model showed that, despite intensification of possum control strategies over time, proximity to forest parks (a principal possum habitat in this area) remained a significant predictor of the number of confirmed cases of TB detected per farm per year. Our analyses showed a significant, three-fold increase in TB risk in dairy cattle relative to beef conditional on the size of local possum habitat, and confirmed the positive influence of cattle population size and the presence of previous infection status as a determinant of the number of confirmed TB cases per farm per year.     

Influence of contact heterogeneity on TB reproduction ratio R0 in a free-living brushtail possum Trichosurus vulpecula population

Social network analyses were used to investigate contact patterns in a free-living possum Trichosurus vulpecula population and to estimate the influence of contact on R(0) for bovine tuberculosis (TB). Using data collected during a five-year capture-mark-recapture study of a free-living possum population, observed estimates of R(0) were computed and compared with R(0) computed from random networks of similar size that approximated a random mixing process. All networks displayed a heterogeneous pattern of contact with the average number of contacts per possum ranging from 20 to 26 per year. The networks consistently showed small-world and single-scale features. The mean estimates of R(0) for TB using the observed contact networks were 1.78, 1.53, 1.53, 1.51, and 1.52 times greater than the corresponding random networks (P <0.05). We estimate that TB would spread if an average of between 1.94 and 1.97 infective contacts occurred per year per infected possum, which is approximately half of that expected from a random network. These results have implications for the management of TB in New Zealand where the possum is the principal wildlife reservoir host of Mycobacterium bovis, the causal agent of bovine TB. This study argues the relevance of refining epidemiological models used to inform disease management policy to account for contact heterogeneity.     

Pregnancy rate after fixed‐time transfer of cryopreserved embryos collected by non‐surgical route in Lacaune sheep

This study investigated the feasibility of applying fixed‐time (cryopreserved) embryo transfer in ewes. Embryos (n = 106) were non‐surgically recovered from superovulated donors (n = 39) on day 6–7 after oestrus. Straws containing one or two embryos (morulae and/or blastocysts) subjected to either slow freezing (SF, n = 62) or vitrification (VT, n = 44) were randomly used within fixed‐time embryo transfer on Day 8.5. Recipient ewes were nulliparous (n = 58) bearing corpora lutea after synchronous oestrous induction protocol. The pregnancy rate was higher (p = .03) in SF (39.4%) than VT (16.9%) and survival rate tended (p = .08) to be higher in SF than in VT (25.8% vs. 15.9%). Lambing rates were similar (p = .13) between SF (20.9%) and VT (15.9%). Embryos recovered by non‐surgical route after cervical dilation treatment and later cryopreserved by either slow freezing or vitrification produced reasonable pregnancy rates after FTET.