The ratio of cardiopulmonary blood volume to stroke volume as an index of cardiac function in horses

A method was developed for determining the ratio of cardiopulmonary blood volume to stroke volume, in horses. The radioisotope 99 Tc (technetium 99m pertechnetate) was injected into the jugular vein as a bolus, which was then detected in the right and left ventricles consecutively by a scanning device consisting of a Na I crystal, a collimator, an amplifier and a discriminator. The radiocardiogram (RCG) and the ECG were recorded simultaneously by a two-channel writing device. The ratio of cardiopulmonary blood volume to stroke volume (cardiopulmonary flow index=CPFI) was then determined from the RCG and ECG tracings.Five categories of horses were examined, viz. Thoroughbreds in training, showjumpers in training, horses not in training, horses with cardiovascular disease and horses with chronic lung disease. The mean CPFI of the above categories were respectively 7.0±0.39, 7.3±0.45, 6.7±0.61, 9.8±1.30 and 6.2±0.47.The mean CPFI of the subjects with heart disease was significantly greater than the mean values of the other four categories (P<0.001).It was concluded that the CPFI was a reproducible physiological parameter in horses and that the value was significantly increased in our series of subjects with heart disease.     

Efficacy and safety of 3 versus 5 days of meloxicam as an analgesic for feline onychectomy and sterilization

Three- or 5-day courses of meloxicam [0.2 mg/kg body weight (BW) subcutaneously pre- or postoperatively on Day 1 followed by 0.05 mg/kg BW, PO per day thereafter] were assessed for analgesic efficacy and safety in 50 client-owned cats undergoing onychectomy and sterilization. Primary outcome parameters were analgesia score, gait/lameness score, and need for rescue analgesia assessed at times 0, 1, 4, 7, 24, 28, 35, 48, 52, 57 hours and on Day 5. Packed cell volume/total solids and serum biochemistry were assessed at time 0 and Days 3 and 5. There were no differences in efficacy and safety parameters regardless of the treatment protocol employed and no cat required rescue analgesia. The patients that received meloxicam preoperatively had statistically better gait/lameness scores than those that received meloxicam postoperatively, supporting the principle of preemptive analgesia.     

Factors affecting the bluetongue virus neutralizing antibody response and the reaction between virus and antibody.

A study was made of different aspects of the bluetongue virus neutralizing antibody response and the reaction between the virus and antibody. Optimum neutralization was obtained in a 2mM Tris-HCl buffer, pH 9,0, at a temperature of 4 degrees C. The reaction of virus and antibody could be demonstrated by electron microscopy in the formation of clumps which were shown to be serotype specific. It was found that both IgM and IgG antibodies can neutralize the virus, but that IgM reached its maximum level sooner after infection than IgG.     

Auxotrophic, plasmid-cured Salmonella enterica serovar typhimurium for use as a live vaccine in calves

Calves were vaccinated orally, subcutaneously or intraperitoneally with a smooth, plasmid-cured strain of Salmonella enterica serovar typhimurium, strain 81. Oral vaccination was not effective, as only 1/5 calves survived challenge with virulent S. typhimurium. Strain 81 was attenuated for calves, as only a slight rise in rectal temperatures was detected after vaccination. The organism was excreted by some calves in the faeces, but no signs of diarrhoea were observed after vaccination. After parenteral vaccination, strain 81 was able to reach the intestines, gastric associated lymphoid tissues and other internal lymphoid tissues and remained viable for up to 14 days in the bovine host. After oral challenge with a virulent strain, 9/10 vaccinated calves survived challenge as opposed to 4/10 control calves (p<0.5). Diarrhoea was present in all calves of the control groups, but in only 4/10 of the vaccinated calves. The clinical reactions of the vaccinated calves were milder than in the control calves, as the rises in rectal temperatures were lower, diarrhoea was less severe, and the challenge strain was present in fewer organs from vaccinated calves than control calves. This study showed that parenterally administered Salmonella vaccines can induce both mucosal and systemic immunity, and it is postulated that this capability of strain 81 is related to its colonisation of lymphoid tissues and other systemic and intestinal tissues. This study confirmed that plasmid-cured strains were attenuated in the bovine host and conferred significant protection after parenteral vaccination, but not oral vaccination.     

VirE1-Mediated Resistance to Crown Gall in Transgenic Arabidopsis thaliana

ABSTRACT Crown gall disease, caused by Agrobacterium tumefaciens, remains a serious agricultural problem despite current biocontrol methods. Agrobacterium tumefaciens transfers single-stranded DNA (T-strands) into plant cells along with several virulence proteins, including a single-stranded DNA-binding protein (VirE2). In plant cells, T-strands are protected from nucleases and targeted to the nucleus by VirE2, which is essential for efficient transmission (transfer and integration) of T-strands. VirE1 is the secretory chaperone for VirE2; it prevents VirE2 from forming aggregates and from binding the T-strands in bacterial cells. Therefore, we hypothesized that sufficient quantities of VirE1 expressed in plant cells might block T-DNA transmission by preventing VirE2 from binding T-strands. Here we show that root explants from Arabidopsis thaliana plants that expressed virE1 formed 3.5-fold fewer tumors than roots from plants without virE1. Also, this resistance was specific for VirE2-mediated Agrobacterium transformation. Plants that have been genetically altered to resist crown gall may prove more effective than biological control.     

Ferroelectricity in free niobium clusters

Electric deflections of gas-phase, cryogenically cooled, neutral niobium clusters [NbN; number of atoms (N) = 2 to 150, temperature (T) = 20to 300kelvin], measured in molecular beams, show that cold clusters may attain an anomalous component with very large electric dipole moments. In contrast, room-temperature measurements show normal metallic polarizabilities. Characteristic energies kBTG(N) [Boltzmann constant kB times a transition temperature TG(N)] are identified, below which the ferroelectric-like state develops. Generally, TG decreases [110 > TG(N) > 10K] as N increases, with pronounced even-odd alternations for N > 38. This new state of metallic matter may be related to bulk superconductivity.     

The toxic effects on cardiac myocytes of tyledoside F, a cumulative neurotoxic cardiac glycoside isolated from Tylecodon grandiflorus

To investigate the cardiac cellular effects of tyledoside F, a cumulative neurotoxic bufadienolide and ouabain, a non-cumulative cardenolide, the whole-cell clamp method was used to measure the Na-K pump current after the Na-K pump had been activated by high intracellular Na2+. The toxic effects of tyledoside F and ouabain on cardiac myocytes were also investigated by observing the effect of the Ca2+ overload on the variability of myocytes during a period of 75 min. From the results it is clear that there are similarities in the direct effects of tyledoside F and ouabain on the Na-K pump. It was found that ouabain inhibited the Na-K pump current more than that of tyledoside F. With regard to Ca2+ overload, there are differences in their mode of production of Ca2+ overload because cinnarizine protects the myocytes against ouabain-induced Ca2+ overload but not against tyledoside-induced Ca2+ overload. This study shows that with the whole-cell clamp technique tyledoside F inhibited the Na-K pump in a manner similar to inhibition of the pump by ouabain. Viability studies with myocytes indicated that tyledoside F also has other effects which are different from these of ouabain.