Surgical resolution of uterine prolapse in three pet rabbits.

This report describes a surgical technique for resolution of uterine prolapse in rabbits. Three pet rabbits presented within 24 hours of parturition with a red mass protruding from the vagina, which was diagnosed as uterine prolapse. In the first case, an attempt to reduce the prolapse by manual compression was ineffective. A laparotomy was used to apply internal uterine traction while simultaneously using gentle external pressure with cotton-tip applicators and resulted in successful resolution. After repositioning, an ovariohysterovaginectomy was performed in all three rabbits. All rabbits recovered uneventfully. Laparotomic repositioning of the uterus and ovariohysterovaginectomy, not previously described in rabbits, was easy to perform and permitted resolution of uterine prolapse.

Assessment of a blood preservation protocol for use in ferrets before transfusion.

Blood transfusion has been described in ferrets as a treatment for oestrus-associated anaemia and as a life-saving therapy following trauma, iatrogenic (usually surgery-induced) anaemia, autoimmune haemolytic anaemia and pure red cell aplasia. Although blood banking is a common method for storage of feline and canine blood it is not currently done with ferret blood. The aim of this study was to determine the shelf-life of ferret blood using the anticoagulant citrate-phosphate-dextrose-solution with adenine (CPDA). Two male ferrets were used as blood donors. From each ferret, 6 ml of blood was taken from the cranial vena cava and stored in 10 ml polyethylene terephthalate (PET) blood tubes containing 1 ml of CPDA solution. Blood was taken from each ferret once per month for five months. These 10 blood samples were stored in a laboratory refrigerator at 4°C for four weeks. Biochemical (glucose, pH, lactate, potassium, sodium) and haematological (haematocrit, light microscopic blood smear examination) analyses were performed on the stored blood at days 0, 7, 14, 21 and 28. Biochemical analyses revealed a progressive decrease from day seven in the stored blood pH, glucose and sodium, with a concomitant increase in lactate and potassium. These results are attributable to the ongoing metabolism and deterioration of the red blood cells (RBC) while in storage, and are more rapid than described for human or canine stored blood. Haematological analyses revealed a progressive elevation of the haematocrit due to the appearance of hypochromic red blood cells and echinocytes beginning at day 7. Haemolysis was observed in the microhaematocrit capillary tube sample by day 21, and microscopic clots were visible on the blood smear by day 28. The low blood pH and the appearance of many hypochromic RBCs and some echinocytes from day 7 in CPDA-stored ferret blood, suggest stored ferret blood has a short shelf-life when compared with stored human or canine blood. We recommend that ferret blood stored in CPDA should not be used for transfusion after seven days of storage at 4°C.

FLOTAC for diagnosis of endo-parasites in pet squirrels in southern Italy.

The present study investigated the occurrence of endoparasites in pet squirrels in southern Italy. Fresh fecal samples were collected from 50 asymptomatic pet squirrels belonging to five different species (Callosciurus finlaysonii, n=6, C. prevosti, n=6; Tamias striatus, n=26, T. sibiricus, n=10; Sciurus carolinensis, n=2) housed both in pet shops and/or in private residences. All fecal samples were processed using the FLOTAC pellet technique to identify and count helminth eggs/larvae and protozoan cysts/oocysts. In addition, to detect Cryptosporidium spp. and Giardia spp. the samples were analyzed by the Remel Xpect(®) immunoassay. Helminth eggs were detected in 9 out of 50 squirrels. Specifically, eggs of Dicrocoelium dendriticum were found in 5 squirrels (C. finlaysonii, n=2; C. prevosti, n=2; T. striatus, n=1); eggs of the pinworm Syphacia spp. in 3 squirrels (C. prevosti, n=2; T. striatus, n=1); and eggs of gastrointestinal nematoda (Nippostrongylus-like) were found in 1 subject (C. prevosti). Finally, two squirrels (C. prevosti) had multiple parasitic infections with D. dendriticum and Capillaria hepatica, and with D. dendriticum and Strongyloides spp., respectively. None of the samples were positive for Cryptosporidium spp. or Giardia spp. or any other protozoa (e.g. Eimeria). To the authors' knowledge, this is the first report of a D. dendriticum natural infection in pet rodents.

Unexpected inhibition of cholesterol 7 alpha-hydroxylase by cholesterol in New Zealand white and Watanabe heritable hyperlipidemic rabbits.

We investigated the effect of cholesterol feeding on plasma cholesterol concentrations, hepatic activities and mRNA levels of HMG-CoA reductase and cholesterol 7 alpha-hydroxylase and hepatic LDL receptor function and mRNA levels in 23 New Zealand White (NZW) and 17 Watanabe heritable hyperlipidemic (WHHL) rabbits. Plasma cholesterol concentrations were 9.9 times greater in WHHL than NZW rabbits and rose significantly in both groups when cholesterol was fed. Baseline liver cholesterol levels were 50% higher but rose only 26% in WHHL as compared with 3.6-fold increase with the cholesterol diet in NZW rabbits. In both rabbit groups, hepatic total HMG-CoA reductase activity was similar and declined > 60% without changing enzyme mRNA levels after cholesterol was fed. In NZW rabbits, cholesterol feeding inhibited LDL receptor function but not mRNA levels. As expected, receptor-mediated LDL binding was reduced in WHHL rabbits. Hepatic cholesterol 7 alpha-hydroxylase activity and mRNA levels were 2.8 and 10.4 times greater in NZW than WHHL rabbits. Unexpectedly, cholesterol 7 alpha-hydroxylase activity was reduced 53% and mRNA levels were reduced 79% in NZW rabbits with 2% cholesterol feeding. These results demonstrate that WHHL as compared with NZW rabbits have markedly elevated plasma and higher liver cholesterol concentrations, less hepatic LDL receptor function, and very low hepatic cholesterol 7 alpha-hydroxylase activity and mRNA levels. Feeding cholesterol to NZW rabbits increased plasma and hepatic concentrations greatly, inhibited LDL receptor-mediated binding, and unexpectedly suppressed cholesterol 7 alpha-hydroxylase activity and mRNA to minimum levels similar to WHHL rabbits. Dietary cholesterol accumulates in the plasma of NZW rabbits, and WHHL rabbits are hypercholesterolemic because reduced LDL receptor function is combined with decreased catabolism of cholesterol to bile acids.

In vivo protection against endotoxin by plasma high density lipoprotein.

Overwhelming bacterial infection is accompanied by fever, hypotension, disseminated intravascular coagulation, and multiple organ failure leading to death in 30-80% of cases. These classical symptoms of septic shock are caused by potent cytokines that are produced in response to endotoxin released from Gram-negative bacteria. Treatments with antibodies and receptor antagonists to block endotoxin or cytokine mediators have given mixed results in clinical trials. High density lipoprotein (HDL) is a natural component of plasma that is known to neutralize endotoxin in vitro. We report here that raising the plasma HDL concentration protects mice against endotoxin in vivo. Transgenic mice with 2-fold-elevated plasma HDL levels had more endotoxin bound to HDL, lower plasma cytokine levels, and improved survival rates compared with low-HDL mice. Intravenous infusion of HDL also protected mice, but only when given as reconstituted HDL prepared from phospholipid and either HDL apoprotein or an 18-amino acid peptide synthesized to mimic the structure of apolipoprotein A-I of HDL. Intact plasma HDL was mildly toxic, and HDL apoprotein was ineffective. The effectiveness of the reconstituted peptide renders very unlikely any significant contribution to protection by trace proteins in apo-HDL. These data suggest a simple leaflet insertion model for binding and neutralization of lipopolysaccharide by phospholipid on the surface of HDL. Plasma HDL may normally act to protect against endotoxin; this protection may be augmented by administration of reconstituted HDL or reconstituted peptides.

High-frequency analysis of the signal-averaged ECG. Correlation with left ventricular mass in rabbits.

Standard electrocardiographic (ECG) criteria have exhibited poor correlation with left ventricular mass and poor sensitivity for left ventricular hypertrophy at acceptable levels of specificity. To assess the ability of the high-frequency filtered signal-averaged ECG to improve ECG correlation with left ventricular mass, signal-averaged orthogonal lead recordings in 29 normal rabbits and seven rabbits with left ventricular hypertrophy due to chronic aortic regurgitation were compared with left ventricular mass corrected for body weight. Voltage of the vector QRS complex was integrated over the total duration of the QRS after separate filtering with standard frequency (0-100 Hz) low-pass and high-frequency (44 Hz) high-pass filters. Measurement of individual X, Y, and Z lead R and S wave voltage was performed on averaged, standard frequency filtered complexes, and the maximal spatial vector magnitude was determined from the standard frequency filtered vectors. Voltage of the 44 Hz high-pass filtered vector QRS complex integrated over the total duration of the QRS (high-frequency vector integral) correlated closely with indexed left ventricular mass (r = 0.84, p less than 0.0001), significantly better than the correlation of standard frequency vector integral or maximal spatial vector magnitude voltages (r = 0.35 and r = 0.61, each p less than 0.01 vs high-frequency vector integral) and the correlation of orthogonal lead X R wave or lead Y S wave voltages (r = 0.55 and r = 0.37, respectively, each p less than 0.01 vs high-frequency vector integral).(ABSTRACT TRUNCATED AT 250 WORDS)

Husbandry, reproduction and postnatal development of the neotropical muroid rodent Zygodontomys brevicauda.

Laboratory colonies of the Neotropical muroid rodent Zygodontomys brevicauda have been employed in studies of arbovirus epidemiology and are currently the subjects of experimental research on tropical mammalian reproductive physiology and evolutionary quantitative genetics. Captive-bred litters typically consist of 4 or 5 pups weighing 3-4 g each at birth. Adults 20-40 weeks old average 60-80 g with some sexual dimorphism. Females are sexually mature at 3-4 weeks of age, males at 6-8 weeks. Ovulation is spontaneous and gestation is 25 days. Preliminary observations are provided on the microbiological status and parasites of captive-bred animals.

Control of variance in experimental studies of hyperlipidemia using the WHHL rabbit.

Between-animal variability has frustrated many experimental studies in outbred animal models of human disease. Variability that arises from genetic heterozygosity can be minimized by use of experimental designs that match littermates (polyzygotic twins) across control and treatment groups. Poor breeding vigor has prevented use of this experimental design in the WHHL rabbit model of hyperlipidemia and atherosclerosis. A comparison of reproduction in WHHL and normal rabbits demonstrated that litter size is limited by functional deficits at ovulation, implantation, and gestation in WHHL females. Superovulation of females reliably produced expanded litters of WHHL rabbits. Plasma lipids were measured in expanded litters of Japanese White WHHL (JW-WW) and English Half-lop WHHL (EHL-WW) rabbits. The variance of plasma cholesterol within sibships was two- to three-fold less than that between-litters. Intraclass correlation of total cholesterol within litters of EHL-WW was 0.72 and within litters of JW-WW was 0.67. These data provide evidence of genetic modulation of hypercholesterolemia in WHHL rabbits and demonstrate that experimental designs in which littermates are paired across groups can decrease the number of animals needed or increase the sensitivity of hypothesis tests by two- to threefold.

The physical-chemical basis for sex-related differences in uptake of fatty acids by the liver.

The uptake of fatty acids by the liver was shown previously to be a non-catalyzed process, and rates of uptake were correlated to the affinity of the plasma membranes of liver cells for fatty acids. The experiments in this paper were designed to test whether the known differences in uptake and metabolism of free fatty acids by the livers of male and female rats could be understood based on differences in the affinities of the corresponding plasma membranes for these substrates. The relative affinities for palmitate and oleate of 'male' plasma membranes were found to be lower versus 'female' membranes. Measurements of uptake of palmitate from albumin-palmitate complexes by 'male' and 'female' perfused livers showed higher uptake rates by the latter when correlated with the concentration of the complex. However, the rates of uptake were identical when the concentrations of the fatty acid in the plasma membranes of male and female liver cells were the same.

Low density lipoprotein receptor-independent hepatic uptake of a synthetic, cholesterol-scavenging lipoprotein: implications for the treatment of receptor-deficient atherosclerosis.

The metabolism of infused 111In-labeled phospholipid liposomes was examined in Watanabe heritable hyperlipidemic (WHHL) rabbits, which lack low density lipoprotein (LDL) receptors, and in normal control rabbits. The half-times (t1/2) for clearance of 111In and excess phospholipid from plasma were 20.8 +/- 0.9 hr and 20.3 +/- 4.6 hr in WHHL and 20.0 +/- 0.8 hr and 19.6 +/- 2.2 hr in the normal rabbits (means +/- SEM; n = 4). By 6 hr postinfusion, the plasma concentration of unesterified cholesterol increased by 2.2 +/- 0.23 mmol/liter in WHHL and 2.1 +/- 0.04 mmol/liter in normal rabbits, presumably reflecting mobilization of tissue stores. Disappearance of excess plasma cholesterol was greater than 90% complete in both groups of rabbits by 70 hr postinfusion. By quantitative gamma camera imaging, hepatic trapping of 111In-labeled liposomes over time was indistinguishable between the two groups. At autopsy, the liver was the major organ of clearance, acquiring 22.0% +/- 1.7% (WHHL) and 16.8% +/- 1.0% (normal of total 111In. Aortic uptake of 111In was less than 0.02%. Thus, mobilization of cholesterol and hepatic uptake of phospholipid liposomes do not require LDL receptors. Because phospholipid infusions produce rapid substantial regression of atherosclerosis in genetically normal animals, our results suggest that phospholipid liposomes or triglyceride phospholipid emulsions (e.g., Intralipid) might reduce atherosclerosis in WHHL rabbits and in humans with familial hypercholesterolemia.