Abomasal size and emptying time in healthy lambs and in lambs affected by watery mouth

Contrast radiography (barium sulphate suspension fed by stomach tube) was used to assess abomasal profile area (a reflection of tone in the abomasal wall) and the rate of abomasal emptying in healthy lambs aged four to 144 hours and in lambs affected by watery mouth. In healthy lambs abomasal profile area increased from 15.1 +/- 0.56 cm2/kg at four hours of age to 23.1 +/- 1.07 cm2/kg at 24 to 48 hours (P less than 0.001). There was no change up to 48 to 72 hours but after this age there was a substantial decrease to 12.8 +/- 0.76 cm2/kg at 120 to 144 hours (P less than 0.001). The rate of abomasal emptying decreased as abomasal profile area increased. Complete emptying of the abomasum was observed within three hours of feeding in the majority of lambs aged four hours (seven out of eight) and 120 to 144 hours (13 out of 16) but only in a minority of lambs aged 24 to 48 hours (one out of 11). In lambs affected by watery mouth (mean age [+/- se] 33 +/- 2.8 hours, n = 34) abomasal profile area was greater and the rate of abomasal emptying was slower than in healthy lambs aged 24 to 48 hours. These findings confirm the previous suspicion that watery mouth is associated with an impairment of gut motility. Abomasal emptying time was prolonged in lambs aged four hours when either ewe or cow colostrum was included with the contrast medium. A similar effect was observed in lambs aged 24 to 48 hours when cow colostrum was included. The castration of lambs aged four hours with rubber rings immediately before the administration of contrast medium had no effect on the rate of abomasal emptying.     

DOPPLER MEASUREMENT OF SPLANCHNIC BLOOD FLOW DURING DIGESTION IN UNSEDATED NORMAL DOGS

The purpose of this study was to measure splanchnic blood flow during digestion in unsedated dogs by using duplex Doppler sonography. The study population consisted of 12 healthy dogs. Blood flow in the cranial mesenteric artery, the celiac artery, and the aorta was measured before a test meal and at 20, 60, and 90 minutes after eating. The following measurements were made or calculated: vessel diameter, peak systolic velocity, end diastolic velocity, mean velocity, resistive index, pulsatility index, and flow volume. There was a significant postprandial decrease in the resistive and pulsatility indices in both the cranial mesenteric (preprandial RI = 0.867, postprandial RI = 0.796, preprandial PI = 3.033, postprandial PI = 2.173) and the celiac (preprandial RI = 0.854, postprandial RI = 0.769, preprandial PI = 2.639, postprandial PI = 1.930) arteries. In both vessels the end diastolic velocity, the mean velocity, and the flow volume increased significantly postprandially. These changes occurred significantly earlier in the celiac artery than in the cranial mesenteric artery. The findings most likely correspond to postprandial splanchnic vasodilation. Doppler ultrasound provide a good methode of detecting changes in postprandial splanchnic blood flow in the dog.     

Location and the Innovation Performance of Commercial GIS Companies

This paper looks at the role of firm size, location, and in‐house research and development (R&D) in the innovation performance of U.S. firms in the commercial geographic information systems (GIS) industry. Data from a survey of 300 GIS firms are presented. The results suggest that innovation‐intensity varies directly with in‐house R&D spending (scaled as a proportion of company sales), but inversely with company size (total employment). Significant regional variations in the innovation performance of GIS firms are identified. It is argued that the geography of innovation is influenced by the spatial distribution of young and/or small firms, in that R&D‐productivity is found to vary inversely with company size. An important finding is that creative inputs to support innovation are almost evenly divided between internal and external sources. A surprising result is that the academic community is not viewed as a particularly important source of new ideas for innovative firms. The paper concludes with a discussion of the implications of the survey data for future empirical work on the GIS sector.     

Rehabilitation of degraded Calluna vulgaris (L.) Hull-dominated wet heath by controlled sheep grazing

Many upland areas of the British Isles have seen declines in the area and condition of heather (Calluna vulgaris)-dominated heathland vegetation. To reverse this decline, management regimes must be designed to rehabilitate areas that have seen this decline. As most of this heathland vegetation is primarily managed by grazing, such management has to determine what stocking levels can maintain the vegetation in a desired state. This paper describes how to reverse this decline through suitable grazing management.A degraded ‘wet-heath’ system, previously grazed at 2.1 sheep ha⁻¹, was subject to a range of grazing treatments over a 5-year period. Treatments varied in intensity (0-1.4 sheep ha⁻¹) and timing (summer only, winter only, or year round) of grazing. Grazing levels were maintained at 2.1 sheep ha⁻¹ outside the fenced areas. Vegetation composition remained stable outside the fenced treatments. All the fenced treatments showed an increase in the relative frequency of the evergreen Calluna vulgaris, with the greatest increase being in the ungrazed treatment, and the least in the year round 1.4 sheep ha⁻¹ treatment. This increase was in line with a reduction in heather utilisation to relatively low and sustainable levels. Other species that benefited from reduced grazing included Carex nigra, Deschampsia flexuosa and to a lesser extent Galium saxatile and Erica tetralix, whereas a range of moss species including Hypnum jutlandicum and Rhytidiadelphus loreus were more frequent at higher grazing levels. Though the recovery of heather was similar in the two seasonally grazed treatments, the vegetation showed different overall trajectories. Winter only grazed allowed a substantial increase in the cover of the deciduous Molinia caerulea, whereas this species was kept in check by summer only grazing. A stocking level of between 0.7 and 1.4 sheep ha⁻¹ appears to be appropriate to maintain and even enhance the cover of heather on degraded wet heath. Complete removal is not necessary. Grazing restricted to the winter period is inappropriate in areas where M. caerulea occurs. Setting appropriate stocking levels to maintain the condition of the vegetation must take into account site conditions, especially the presence of species that can affect the utilisation of heather.     

Electrophoretic heterogeneity of polypeptide chains of specific antibodies

Heavy and light polypeptide chains isolated from different specific antibodies to haptens and from (gamma)G-immunoglobulin of normal rabbits have been resolved into distinct, multiple components by disc electrophoresis in polyacrylamide gels in the presence of urea. In spite of the resolution of these chains into multiple bands, different specific antibodies and normal rabbit (gamma)G-immunoglobulin were indistinguishable from each other by this method.     

Cloned viral protein vaccine for foot-and-mouth disease: responses in cattle and swine

A DNA sequence coding for the immunogenic capsid protein VP3 of foot-and-mouth disease virus A12, prepared from the virion RNA, was ligated to a plasmid designed to express a chimeric protein from the Escherichia coli tryptophan promoter-operator system. When Escherichia coli transformed with this plasmid was grown in tryptophan-depleted media, approximately 17 percent of the total cellular protein was found to be an insoluble and stable chimeric protein. The purified chimeric protein competed equally on a molar basis with VP3 for specific antibodies to foot-and-mouth disease virus. When inoculated into six cattle and two swine, this protein elicited high levels of neutralizing antibody and protection against challenge with foot-and-mouth disease virus.     

Band gap fluorescence from individual single-walled carbon nanotubes

Fluorescence has been observed directly across the band gap of semiconducting carbon nanotubes. We obtained individual nanotubes, each encased in a cylindrical micelle, by ultrasonically agitating an aqueous dispersion of raw single-walled carbon nanotubes in sodium dodecyl sulfate and then centrifuging to remove tube bundles, ropes, and residual catalyst. Aggregation of nanotubes into bundles otherwise quenches the fluorescence through interactions with metallic tubes and substantially broadens the absorption spectra. At pH less than 5, the absorption and emission spectra of individual nanotubes show evidence of band gap-selective protonation of the side walls of the tube. This protonation is readily reversed by treatment with base or ultraviolet light.     

A class of potent antimalarials and their specific accumulation in infected erythrocytes

During asexual development within erythrocytes, malaria parasites synthesize considerable amounts of membrane. This activity provides an attractive target for chemotherapy because it is absent from mature erythrocytes. We found that compounds that inhibit phosphatidylcholine biosynthesis de novo from choline were potent antimalarial drugs. The lead compound, G25, potently inhibited in vitro growth of the human malaria parasites Plasmodium falciparum and P. vivax and was 1000-fold less toxic to mammalian cell lines. A radioactive derivative specifically accumulated in infected erythrocytes to levels several hundredfold higher than in the surrounding medium, and very low dose G25 therapy completely cured monkeys infected with P. falciparum and P. cynomolgi.     

Colostral immunoglobulin-A: synthesis in vitro of T-chain by rabbit mammary gland

When minced mammary tissue from lactating rabbits was incubated in vitro with C(14)-labeled lysine and isoleucine, it incorporated radio-activity into colostral immunoglobulin A. The only portion of this colostral molecule with significant labeling was T-chain, with little or no labeling of light or heavy chains. It was thus demonstrated that T-chains are synthesized by mammary gland. Because the remainder of the molecule was derived from unlabeled material, in vivo it was probably derived from serum.