Rat neonatal intestinal wall-free graft

An experimental study was carried out in order to evaluate the regeneration capacity of the neonatal intestinal wall in ischaemia and its repercussion over organs of the immune system such as the spleen. We isolated a reservoir of small intestine in adult Sprague-Dawley rats that, after having been everted and placed at a subcutaneous level, was grafted with a free small intestine segment of neonatal Sprague-Dawley rats and analysed 3, 15 and 30 days after grafting. Samples obtained were stained with Martin's trichromic stain and studied at the light microscopic level. A total regeneration of the crypt architecture, formed by absorptive enterocytes, was observed in the interior of the reservoirs. A quantitative immunohistochemical study with monoclonal antibodies against CD4, CD8, MHC I and MHC II was carried out in the spleen of these animals. An additional immunohistochemical study was also performed in the small intestine reservoirs and spleen of transplanted animals using nitric oxide synthase (NOS) antibodies. Three days after transplantation NOS immunoreactive cells were observed in the reservoirs with transplanted neonatal small intestine. Antigenic stimulation produced, in the spleen red pulp of transplanted animals, a significant increase (P < 0.001) in the percentage of NOS, CD8 and MHC I immunoreactive cells in relation with values observed in control animals. These morphometric changes could be related with the stimulation that nitric oxide produces in the proliferation of the cytotoxic T cells.     

Efficacy of phosphomycin in the control of Escherichia coli infection of broiler chickens

Seventy-five 25-day-old broilers were divided into three groups: group I unmedicated and challenged with E coli 078:K80; group F infected and treated with 150 ppm of phosphomycin in their drinking water, and group C acted as a control. Their weights, feed intake, clinical signs, macroscopic lesions, E coli reisolation, and serum biochemistry were compared. Group F showed fewer symptoms and gross lesions than those from group I while the average daily gain, bodyweight, and feed intake were similar to the control group. E coli was reisolated in 32 per cent of the livers and spleens from group I, compared with 4 per cent of liver and 8 per cent of spleens from group F. There was an increase in the levels of total protein and globulins in group I but not in group F. These results provide evidence of the therapeutic efficacy of phosphomycin in the control of an experimental E coli infection in broiler chickens.     

Cytologic and histologic features of a poorly differentiated glioma in a dog

A 5-year old female Boxer with a 1-week history of progressive paresis and paraplegia had a T10-13 subarachnoid filling defect on myelography. Exploratory hemilaminectomy revealed an intramedullary spinal cord tumor which was subsequently diagnosed as a poorly differentiated glioma, most likely an anaplastic ependymoma. The cytologic, histologic, and immunocytochemical staining characteristics of this neoplasm are described. Differential diagnoses, including primary and secondary tumors involving the central nervous system are discussed.     

Effect of beta‐aminoproprionitrile on eggshell formation

1. Eggshells are bioceramic‐biopolymer composites made by a cell‐mediated deposition of an extracellular matrix which drives the organisation of the inorganic phase. Ultrastructurally, eggshells are composed of shell membranes, mammillary knobs, palisade, and cuticle. Shell membranes are two nets of type X collagen‐containing fibrils. On to these membranes, the mammillary knobs, that is, the crystal nucleation sites, are deposited. Type X collagen is highly cross‐linked and insoluble.

2. In order to evaluate the role of type X collagen cross‐linking on eggshell formation, hens were injected with different doses of β‐aminoproprionitrile, which specifically interferes with cross‐link formation.

3. Changes in egg size and shape were observed. Scanning electron micrographs analysis of these eggs demonstrated marked changes in crystal growth and shell membrane structure and arrangement. A dot‐blot analysis, using a monoclonal antibody against chicken type X collagen, shows a dose‐dependent increase in shell membrane collagen extractability.

4. It is concluded that the formation of β‐aminoproprionitrile‐sensitive cross‐links among the type X collagen molecules of the shell membranes play an essential role in normal eggshell formation.     

Microbial response of an acid forest soil to experimental soil warming

 Effects of increased soil temperature on soil microbial biomass and dehydrogenase activity were examined on organic (O) horizon material in a low-elevation spruce-fir ecosystem. Soil temperature was maintained at 5  °C above ambient during the growing season in the experimental plots, and soil temperature, moisture, microbial biomass, and dehydrogenase activity were measured during the experiment. An incubation study was also conducted under three temperature regimes, 5, 15, and 25  °C, and under four moisture regimes of 20, 120, 220, and 320% to further evaluate these environmental factors on dehydrogenase activity and microbial biomass. Soil moisture content and microbial biomass controls were significantly lower (30% and 2 μg g^–1 soil, respectively) in the heated plots during the treatment period, suggesting that moisture content was important in controlling microbial biomass. In the incubation study, temperature appeared more important than moisture in controlling microbial biomass and dehydrogenase activity. Increasing temperature between 5  °C and 25  °C resulted in significant decreases in microbial biomass and dehydrogenase activity. Received: 7 August 1998     

Demography of Lolium rigidum in winter barley crops: analysis of recruitment,survival and reproduction

Demographic studies were conducted with Lolium rigidum Gaud. growing in winter barley crops at five sites in central and eastern Spain, over a period of 2 or 3 years. Although threefold differences (34–97%) in annual recruitment were recorded in the various experiments, most of the values were close to the overall average (67%). Seedling emergence took place in a very short period of time after sowing, with 90% emergence generally being reached after a thermal time of 242 d°C (provided soil moisture was adequate at sowing). Seedling survival was very high (78–95%) in most experiments, with no clear relationship between this parameter and any of the environmental variables studied. Survival curves were relatively linear, with plant mortality increasing gradually throughout the life cycle of the plant. There were 34‐fold differences (from 7 to 237 seeds per plant) in the fecundities recorded in the various experiments. Variation in fecundity resulted partly from differences in crop and weed densities and total precipitation received during the growth cycle. The annual rate of population growth was estimated based on the above‐mentioned parameters. The potential for population growth was high (average λ=6.21), but large differences were obtained for the different sites and years.     

Study of Calcium Ion Diffusion in Nixtamalized Quality Protein Maize as a Function of Cooking Temperature

In this report, the effect of temperature on the calcium content of Quality Protein Maize (QPM H-368C) during the nixtamalization process as a function of the steeping time for three cooking temperatures (72, 82, and 92°C) is presented. Also, for the first time, we report in physico-chemical terms the end of the cooking stage during the nixtamalization process that was established when the moisture content in corn kernels reached a value of 36% (w/w) with a lime concentration of 1% (w/v), independent of the cooking temperature. Atomic absorption spectroscopy was used to determine the calcium concentration in the whole kernel and in its different anatomical components (pericarp, endosperm, and germ) as well as in 10% of the outermost layers, the next 10%, and the remaining 80% of the endosperm as a function of the steeping time. It was found that if the cooking temperature increases, the calcium content increases also. For steeping times in the range of 5–7 hr, a relative maximum was found in the calcium contents of 0.24, 0.21, and 0.18% (w/w) in QPM H-368 flours at 92, 82, and 72°C, respectively. Calcium was found in the most external layers in the endosperm and minimum diffusion occurs in the internal 80%. Phosphorous was measured by using UV spectroscopy and the results showed that it remains constant at 0.24% throughout the process. Scanning electron microscopy analysis was used to explain the calcium ion diffusion in the kernel. The physical changes in the pericarp govern the calcium diffusion process.