Accuracy of formulae for calculating left ventricular volumes of the equine heart

Echocardiography may be an accurate method of measuring left ventricular (LV) volumes and mass of the horse's heart. If so, studies of the heart size and hypertrophy would be possible. This study evaluated geometric models of the external and internal LV shapes, to determine which could be applied to echocardiographic measurements. We preserved 30 horses' hearts and measured their dimensions and cross sectional areas. These measurements were entered into seven formulae representing different geometric models of the ventricle and its chamber. We derived a correction factor to estimate the long axis as a fixed proportion of the external diameter, so that volumes could be determined from an M-mode or a cross sectional echocardiogram. Statistical analysis of the regressions of known volumes against calculated volumes measured by water displacement, demonstrated that the ellipsoid formula using cross sectional areas was very accurate in representing the external shape of the left ventricle (slope = 1.01 r2 = 96.3) and its chamber (slope = 0.83, r2 = 94.3). Myocardial volume, measured by subtracting internal (chamber) volume from external volume, was also calculated accurately (slope = 1.01, r2 = 96.5). The ellipsoid formula using directly measured diameter was only slightly less accurate. LV mass could be calculated by applying the specific gravity of equine myocardium, 1.05, to the myocardial volume. Formulae recommended for evaluating are, with M-mode echocardiography: [equation: see text] and with 2D echocardiography [equation: see text] where De is the external diameter, Di is the internal diameter, Ae the external area and Ai the internal area.     

Effects of persistency and production on the genetic parameters of milk and fat yield in Israeli-Holsteins

Herd-years of Israeli-Holsteins were stratified into three groups by two criteria: mean annualized milk yield [365 (total lactations yield/calving interval)] and mean persistency, estimated as the ratio of daily milk production at the 5th mo postpartum to daily production during the postpartum peak period. The latter was taken as an indication of the relative environmental stress on the cow. Primi- and multiparous cows were analyzed separately. Genetic parameters were estimated for annualized milk and fat production at each production and persistency group. Heritabilities increased with a rise in production for both primiparous and multiparous cows, but the effect was greater for multiparous cows. Even though persistency and production were correlated, no clear trends were evident for stratification by persistency; thus, a relationship between stress and heritability was not established. Genetic correlations among stratification groups were between .7 and .9 for persistency and between .6 and .86 for production; thus, sire x environmental interaction was greater for production than for persistency stratification. Production in a given year can be used as a criterion for selecting herds to test progeny of young sires in the following year.     

Internal friction of the glassy tektites

Tektites are naturally occurring glasses, perhaps of meteoritic origin. They occur all over the world. They range in size from μm to decimeter. They are based on the compounds silica and alumina, with smaller concentrations of alkali metal and transition metal oxides. Their origin is in vigorous dispute; some scientists think they are of terrestrial earth origin, others believe they come from interplanetary space, as is true of meteorites. We have secured seven specimens from various regions of the earth and have measured the internal friction spectrum of several in the kilocycle frequency range above room temperature, where internal friction peaks of synthetic glasses have been observed. A well defined loss peak is observed around 500 K in a number of specimens. We have also measured the loss spectrum of obsidian and of blast furnace slag. From comparison of these measurements, we conclude that tektites are probably of volcanic origin, the loss peaks being associated with the reorientation of Fe–oxygen complexes.     

Adenovirus-mediated gene transfer of inhibitors of apoptosis protein delays apoptosis in cerebellar granule neurons

The inhibitor of apoptosis (IAP) family of antiapoptotic genes, originally discovered in baculovirus, exists in animals ranging from insects to humans. Here, we investigated the ability of IAPs to suppress cell death in both a neuronal model of apoptosis and excitotoxicity. Cerebellar granule neurons undergo apoptosis when switched from 25 to 5 mM potassium, and excitotoxic cell death in response to glutamate. We examined the endogenous expression of four members of the IAP family, X chromosome-linked IAP (XIAP), rat IAP1 (RIAP1), RIAP2, and neuronal apoptosis inhibitory protein (NAIP), by semiquantitative reverse PCR and immunoblot analysis in cultured cerebellar granule neurons. Cerebellar granule neurons express significant levels of RIAP2 mRNA and protein, but expression of RIAP1, NAIP, and XIAP was not detected. RIAP2 mRNA content and protein levels did not change when cells were switched from 25 to 5 mM potassium. To determine whether ectopic expression of IAP influenced neuronal survival after potassium withdrawal or glutamate exposure, we used recombinant adenoviral vectors to target XIAP, human IAP1 (HIAP1), HIAP2, and NAIP into cerebellar granule neurons. We demonstrate that forced expression of IAPs efficiently blocked potassium withdrawal-induced N-acetyl-Asp-Glu-Val-Asp-specific caspase activity and reduced DNA fragmentation. However, neurons were only protected from apoptosis up to 24 h after potassium withdrawal, but not at later time points, suggesting that IAPs delay but do not block apoptosis in cerebellar granule neurons. In contrast, treatment with 100 microM or 1 mM glutamate did not induce caspase activity and adenoviral-mediated expression of IAPs had no influence on subsequent excitotoxic cell death.     

Zur Bestimmung der St?rke in Wurstwaaren

Ohne Zusammenfassung     

Limiting zeros of decouplable MIMO systems

For sufficiently rapid zero-order hold (ZOH) sampling, it is known that the zeros of single-input/single-output discrete-time systems expressed in the forward shift operator converge to values determined only by the degrees of the finite and infinite zeros of the underlying continuous-time system. In this paper, it is shown how this result can be generalized to multi-input/multi-output (MIMO) systems decouplable by static-state feedback (equivalently, having a diagonal interactor matrix). In the fast sampling limit, the authors show how invariant and infinite zero structure is mapped under ZOH sampling for discrete-time systems expressed in either the delta (forward difference) or forward shift operators     

Compensation for decreased expression of B7 molecules on Leishmania infantum-infected canine macrophages results in restoration of parasite-specific T-cell proliferation and gamma interferon production

Infection of humans and dogs by Leishmania infantum may result in visceral leishmaniasis, which is characterized by impaired T-cell-mediated immune responses to parasite antigens. Dogs are natural hosts of Leishmania parasites and play an important role in the transmission of the parasites to humans. In an effort to characterize the immune response in dogs infected with this intracellular pathogen, we examined how infection with L. infantum affects canine macrophages and the consequences for T-cell activation in vitro. We showed that the proliferation of T-cell lines to cognate antigen decreases to background levels when infected autologous monocyte-derived macrophages are used as antigen-presenting cells (APC). The observed reduction of antigen-specific T-cell proliferation was shown to be dependent on the parasite load and to require cell-to-cell interaction of T cells with the infected APC. In addition, we observed a decreased expression of costimulatory B7 molecules on infected monocyte-derived macrophages. The expression of other surface molecules involved in T-cell activation, such as major histocompatibility complex class I and class II, on these cells did not change upon infection, whereas the expression of intracellular adhesion molecule 1 was marginally increased. Compensation for the decreased expression of B7 molecules by the addition of B7-transfected cells resulted in the restoration of cell proliferation and gamma interferon (IFN-gamma) production by a Leishmania-specific T-cell line. These results showed that for the activation of parasite-specific canine T cells producing IFN-gamma, which are most likely involved in protective immunity, sufficient expression of B7 molecules on infected macrophages is required. Provision of costimulatory molecules may be an approach for immunotherapy of leishmaniaisis as well as for vaccine development.