NONINVASIVE ESTIMATION OF CENTRAL VENOUS PRESSURE IN ANESTHETIZED DOGS BY MEASUREMENT OF HEPATIC VENOUS BLOOD FLOW VELOCITY AND ABDOMINAL VENOUS DIAMETER

Determination of central venous pressure (CVP) is relevant to patients with right heart disease, hypovolemia, and following intravenous fluid therapy. We hypothesized that changes in CVP in dogs could be predicted by measurements of hepatic vein diameter, caudal vena cava (CVC) diameter, and hepatic venous flow velocities. Nine healthy American Foxhounds were anesthetized. Following baseline recordings, intravenous fluids were administered to increase CVP. Volume administration created treatment periods with CVP ranges of 5, 10, 15, 20, and 25 mm Hg. Flow velocities in the right medial hepatic vein were recorded using pulsed wave Doppler ultrasound. Hepatic vein, CVC, and aorta diameters were determined with B‐mode ultrasound. Variables were compared across the treatment periods by ANOVA for repeated measures. Relationships between CVP, Doppler, and B‐mode variables were evaluated using Spearman's rank correlations, multiple linear regression, and repeated measures linear regression. The a‐, S‐ and v‐wave velocities were augmented significantly with volume loading. The best part (semipartial) correlation coefficients predicting increasing CVP were identified with v‐wave velocity (0.823), S‐wave velocity (?0.800), CVC diameter (0.855), and hepatic vein diameter (0.815). Multiple linear regression indicated that CVP in this study could be predicted best by a combination of CVC and hepatic vein diameter and the v‐wave velocity (r=0.928). Ultrasound imaging identified gallbladder and pancreatic edema consistently, likely related to acute volume loading. These findings may be applicable in the assessment of volume status, dogs with right heart disease, and during serial monitoring of dogs receiving fluid or diuretic therapy.     

WetUp: a software tool to display approximate wetting patterns from drippers

Knowledge of the wetted perimeter of soil arising from infiltration of water from trickle irrigation drippers is important in the design and management of efficient systems. A user-friendly software tool, WetUp, has been developed to help highlight the impact of soils on water distribution in trickle-irrigated systems. WetUp determines the approximate radial and vertical wetting distances from an emitter in homogeneous soils calculated using analytical methods, and then uses an elliptical plotting function to approximate the expected wetted perimeter. In this paper we describe WetUp and use examples to demonstrate how it can be applied. We also compare the wetted perimeter predicted using WetUp with that predicted by other methods. Results show that the wetting pattern is well described by the ellipsoidal approximation for slowly permeable soils, but that it tends to underestimate the radial wetting in highly permeable soils, particularly as the volume of applied water increases. The error is, however, small in most cases, and of minimal concern when applying WetUp to illustrate the important role that soil hydraulic properties play in determining wetting patterns.Communicated by J. Annandale     

Crystal and molecular structures of rhenium heptafluoride

Rhenium heptafluoride, ReF(7), is one of only two stable binary compounds MX(7) with a heptacoordinated metal atom M and halide atom X. Its low-temperature crystal structure, as determined by high-resolution powder neutron diffraction, reveals the molecular structure, which has been the subject of speculation and debate for many years. Here it is shown within experimental error that at 1.5 kelvin the lowest energy configuration of ReF(7) has symmetry Cs (m) and is a distorted pentagonal bipyramid. The deviation of the two axial Re-F bonds from collinear and the puckering of the ring of equatorial fluorine atoms are similar to what has been postulated as one of the conformations of the pseudorotational motion observed at higher temperatures.     

Morphine-3-succinyl--bovine serum albumin: an immunogenic hapten-protein conjugate

Morphine-3-hemisuccinate was synthesized by reaction of morphine with succinic anhydride. This compound was conjugated to bovine serum albumin by the mixed anhydride method, and the degree of conjugation was determined by base hydrolysis of the conjugate, extraction, and measurement of free morphine. An average of 6.5 molecules of morphine were conjugated to each molecule of protein. Eleven rabbits immunized with varying doses of the conjugate were producing antibody 8 weeks later, as determined by a modification of the ammonium sulfate method, which measures primary binding of antigen by antibody.     

Rejection of renal allografts: specific immunologic suppression

Kidneys were transplanted across a major genetic barrier (Ag-B locus), from LewisxBN F(1) hybrid rats into bilaterally nephrectomized Lewis rats. Survival of grafts is prolonged (indefinite?) in rats treated with a combination of (i) intravenous injection of donor spleen cells 1 day before the graft, and (ii) passive immunization with antiserum prepared in rats of the recipient strain against donor spleen and lymph-node cells. The recipient's immune response to other antigens is not impaired.