The accessory lung lobe in thoracic disease: a case series and anatomical review

Diseases of the accessory lung lobe (AccLL) are often overlooked in dogs and cats, perhaps because of its recessed location. Diseases of this lobe also can mimic diseases of the diaphragm or structures comprising the caudal mediastinum. Normal anatomy of the AccLL and the diagnostic tools used today will be reviewed to help differentiate disease of adjacent organs. Four cases will also be described to illustrate disease presentation and radiographic findings affecting this lobe.     

Mineralized paraprostatic cyst as a potential contributing factor in the development of perineal hernias in a dog

Perineal hernias almost exclusively affect male dogs (sexually intact or castrated). Factors that may contribute or predispose a dog to perineal hernias include tenesmus, pelvic musculature variations (male vs female), and gonadal hormone influence. In dogs with perineal hernias and tenesmus it is important to include rectal and prostatic diseases, including paraprostatic cysts, in the differential list of potential underlying causes. Surgical correction of the perineal hernia with a perineal herniorrhaphy is indicated. Successful treatment depends on the degree of preexisting neurologic alterations, meticulous surgical technique, and identification and correction of underlying contributing factors. Paraprostatic cysts develop predominantly in sexually intact medium to large breed dogs. These cysts are thin-walled structures often attached to the prostatic dorsal midline. Osseous metaplasia of paraprostatic cysts may occur. Clinical signs of tenesmus often result from compression on adjacent structures (urinary bladder and colon), and tenesmus may contribute to the development of perineal hernias. Preferred treatment of a paraprostatic cyst is surgical removal and castration. This report describes a dog with bilateral perineal hernias and a large mineralized paraprostatic cyst that was identified as a possible contributing factor to the hernias.     

Review of left-to-right shunting patent ductus arteriosus and short term outcome in 98 dogs

The case records of 98 dogs with a left-to-right shunting patent ductus arteriosus (PDA) were reviewed. There were 35 breeds represented, with a female to male ratio of 3:1. Forty per cent of the dogs were older than one year at initial presentation and 31 per cent had clinical signs attributable to PDA. A left heart base continuous murmur of grade IV/VI or higher was noted in 90 per cent of the dogs. On electrocardiography, the most common abnormalities were tall R waves (63 per cent) and deep QII waves (62 per cent). The radiographic triad of dilation of the descending aorta with enlargement of the main pulmonary artery segment and left atrium, typical of PDA, was noted in only 26 per cent of cases. Two-dimensional (2D) and M-mode echocardiography detected left atrial enlargement (35 per cent) and an increased left ventricular diameter in diastole (82 per cent) and systole (84 per cent) as the most common abnormalities. Doppler echocardiography demonstrated increased aortic outflow velocities in 66 per cent of cases. The overall short-term successful outcome in this study was 95 per cent. There was no significant difference between surgical ductal ligation using a standard technique or the Jackson-Henderson technique in terms of survival, occurrence of haemorrhage or residual shunting. The number of interventional procedures used in this study was too low for statistical comparison, but there appeared to be a trend towards a higher rate of residual shunting and a lower fatality rate using a coil occlusion technique.     

Protective Effects Against Erwinia amylovora Induced by hrp Mutants in the Whole Plant are Only Partially Mimicked in Cultivated Cells

A virulent strain of Erwinia amylovora, the causal agent of fire blight of Maloideae, and two of its non-virulent hrp mutants (a secretory and a regulatory mutant) were inoculated into apple cell suspensions either alone or in mixed inoculations. In single inoculations, death of 4- to 5-day-old apple cells occurred only when the concentration of the virulent strain of E. amylovora reached a threshold inoculum concentration of 10⁴CFUml^–1, while high concentrations of the hrp mutants were unable to kill apple cells. When mixed inoculated with the virulent parental strain, both hrp mutants protected apple cells from death caused by the virulent strain. The protective effect was associated with a decrease in the population level of the virulent strain and it was dependent on the non-virulent to virulent inoculum concentration suggesting a competition between the non-virulent mutant and the virulent strain. However, no differential protective ability between the two types of mutants could be noticed, contrary to previous results obtained with apple seedlings or apple flowers in which the regulatory mutant was significantly more effective than the secretory mutant. In conclusion, inoculation of apple cell cultures with E. amylovora does not seem to be a model suitable for investigating mechanisms leading to protection.     

Adhesion receptor CD11b/CD18 contributes to neutrophil diapedesis across the bovine blood-milk barrier

epithelium. Neutrophil migration across mammary arterial endothelial cells was almost completely dependent on CD18, the beta-chain of the beta(2) integrins, and to a lesser extent on CD11b, one of the alpha-chains of the beta(2) integrins. Neutrophil migration across collagen was partially blocked by monoclonal antibodies to CD18. No inhibition was observed by monoclonal antibodies to CD11b. Conversely, neutrophil diapedesis across mammary epithelial cells was dependent to a greater extent on CD11b. These results provide evidence for different CD11b/CD18-dependent mechanisms for neutrophil diapedesis across the various cell layers of the blood-milk barrier.     

Early dexamethasone treatment after implantation of a sciatic-nerve cuff decreases the concentration of substance P in the lumbar spinal cord of rats with neuropathic pain

The main purpose of this study was to evaluate the effects of early dexamethasone treatment on pain-related peptides at an early stage in the development of neuropathic pain induced by implantation of a sciatic nerve cuff in Sprague Dawley rats (body weight 250 to 350 g). The rats were tested for touch sensitivity with the use of von Frey filaments before and 3 d after cuff implantation (n = 12) or sham surgery (n = 6). Half of the cuff-implanted rats received dexamethasone, 1 mg/kg intraperitoneally, 1 h after surgery. Spinal cords were collected on the 3rd day after surgery, and the lumbar enlargement was processed for the detection of selected peptides (neurotensin, substance P, cholecystokinin [CCK], vasoactive intestinal peptide, and calcitonin gene-related peptide) by means of liquid chromatography and tandem mass spectrometry. The right sciatic nerve of each rat was collected, fixed, and stained for histopathological evaluation. Except for neurotensin, all the peptides showed an increased concentration with neuropathic pain; however, the differences were significant (P < 0.05) only for substance P and CCK. In the animals treated with dexamethasone, mechanical allodynia was less pronounced (P < 0.01), and only the concentration of substance P was decreased significantly (P < 0.05). Sciatic nerve sections showed a decrease in C (P < 0.01) and Adelta (P < 0.03) fibres with neuropathic pain and a nearly normal percentage of C fibres after dexamethasone treatment. The dexamethasone-treated animals also had less inflammation detectable microscopically at the nerve constriction site compared with cuff-implanted animals that were not treated with dexamethasone. Our results suggest that in the early stages of neuropathic pain induced by an inflammatory process, dexamethasone may be a useful treatment and that substance P plays an important role in pain perception.     

Morphological and hydraulic properties of a silt loam soil in New Zealand as affected by cropping history

Abstract. A rotation trial of four years' pasture followed by two years' arable was used to study the effect of cropping on the morphological and hydraulic properties of soil. An adjacent paddock in grass for the past 35 years was included as a permanent pasture reference. Initial infiltration and field saturated hydraulic conductivity ( K _fs) were least for cultivated soil and increased with increasing time under pasture. This could be explained by the contrasting porosities of resin-impregnated blocks of undisturbed soil which had been infiltrated with methylene blue dye. Small K _fs values for cultivated soil resulted mainly from a thin surface crust, although pore discontinuity at the depth of the cultivation pan (130 mm) could also have contributed. Greater K _fs values under short-term pasture resulted primarily from water flowing through biogenic pores connected to the surface. The greatest K _fs values were in soil that had been under pasture for 35 years (P35). This was attributed to flow through biogenic pores and fissures associated with the strongly-developed subangular blocky structure. The amount of water that infiltrated the two- and four-year pasture soils (P2 and P4) under ponding was 2.5 and 5 times greater, respectively, than the soil that had been cultivated for two years (C2).
As irrigation duration cannot be varied under the border-dyking system used on the Canterbury Plains, the interval between irrigations must be varied if the same total amount of water is to be applied to each of these soils through the season. The interval should be less for the cultivated soil than for those under pasture, and should increase with increasing time under pasture (i.e. P35 > P4 > P2 > C2).     

Impact of successive drought and re-watering cycles on growth and specific leaf area of two Populus x canadensis (Moench) clones, 'Dorskamp' and 'Luisa_Avanzo'

Responses to successive drought and re-watering cycles (1-3 cycles) were compared in greenhouse-grown cuttings of Populus x canadensis (Moench) clones, 'Luisa_ Avanzo' and 'Dorskamp.' Total leaf number increment rate, duration of leaf expansion, total and individual leaf area expansion rates and stomatal conductance were recorded periodically during the experiment. Soil water content (SWC) and predawn leaf water potential (Psi(WP)) were measured four times during each drought cycle. In parallel, relative leaf water content (RWC) and specific leaf area (SLA) were estimated on leaves collected from the top to bottom of each cutting. Under well-watered conditions, 'Luisa_Avanzo' and 'Dorskamp' differed in their patterns of leaf area expansion. Although duration of leaf expansion was similar between clones, 'Luisa_ Avanzo' exhibited higher total leaf number increment rates and individual leaf area increases than 'Dorskamp.' As a result, 'Luisa_Avanzo' cuttings reached larger individual and total leaf areas than 'Dorskamp.' 'Dorskamp' leaves had lower SLA than 'Luisa_Avanzo' leaves. In response to successive drought cycles, both clones underwent decreases in total leaf number increment rates and in total leaf area expansion rates, but both whole-plant and individual leaf areas were drastically reduced only in 'Luisa_Avanzo.' 'Dorskamp' maintained a constant leaf area as a result of an increase in the duration of leaf expansion during drought and a significant stimulation of individual leaf area expansion rate and total leaf number increment rate in response to re-watering. Drought caused a greater decrease in SLA in 'Luisa_Avanzo' than in 'Dorskamp.' Expanded leaves of 'Dorskamp' were constitutively dense or thick, or both, whereas leaves of 'Luisa_Avanzo' became dense or thick, or both, only in response to drought. In both clones, re-watering caused partial recovery of SLA to control values. Our data confirm previous field and greenhouse observations that 'Dorskamp' is more tolerant to successive drought and re-watering cycles than 'Luisa_Avanzo.' We conclude that this difference is mainly attributable to the plasticity of 'Dorskamp' after re-watering, rather than to clonal differences in drought responses.     

Differential responses of Bolivian timber species to prescribed fire and other gap treatments

We followed the establishment and growth response of 13 commercial tree species to canopy opening, above-ground biomass removal, and experimental burns of low and high intensities in a lowland dry forest in Bolivia. Three patterns of response to treatments were observed among the most abundant commercial tree species. (1) Shade-intolerant species regenerated mostly from seed and had the highest survival and growth rates following high-intensity burns. (2) Shade-tolerant species were abundant in gap control and plant removal treatments. Treatments had little effect on the height growth of these species. (3) Individuals of root sprouting species were most abundant following plant removal and low-intensity burn treatments. Treatments had little effect on the height growth of these species. The wide variation in species responses to gap treatments found in this study not only reinforces the concept that species are distributed along a continuum of shade-tolerance levels, but that other aspects of species biology, such as seed dispersal type or sprouting behavior, further differentiate regeneration strategies. The variety of regeneration strategies found among the species at this forest site will require a flexible management scheme that mixes more intensive silvicultural treatments such as prescribed burning with less intensive treatments.