The Renin-Angiotensin-Aldosterone System in Greyhounds and Non-Greyhound Dogs

Background

The renin‐angiotensin‐aldosterone system (RAAS) regulates blood pressure, electrolyte homeostasis, and renal function. Blood pressure, serum sodium concentrations, and urinary albumin excretion are higher in Greyhounds than other purebred and mixed‐breed dogs.

Hypothesis

Alterations in the RAAS in Greyhounds are associated with hemodynamic and clinicopathologic differences observed in the breed.

Animals

Clinically healthy Greyhound and non‐Greyhound dogs consecutively enrolled as blood donors (n = 20/group).

Methods

Prospective study. Standard chemical analysis was performed on serum and urine. Serum angiotensin‐converting enzyme (ACE) activity was determined by fluorometric assay. All other RAAS hormones were determined by radioimmunoassay. Symmetric dimethylarginine (SDMA) was measured by immunoassay. Measurements were compared to blood pressure and urine albumin concentration. Data are presented as mean ± SD or median, range.

Results

Serum creatinine (1.5 ± 0.2 vs 1.0 ± 0.1 mg/dL, P < .001), sodium (149, 147–152 vs 148, 146–150 mEq/L, P = .017), and SDMA (16.1 ± 2.9 vs 12.2 ± 1.8 μg/dL, P < .001) were significantly higher in Greyhounds versus non‐Greyhounds, respectively. Plasma renin activity (0.69, 0.10–1.93 vs 0.65, 0.27–2.93 ng/mL/h, P = .60) and ACE activity (4.5, 2.1–8.5 vs 4.6, 2.1–11.4 activity/mL; P = .77) were similar between groups and did not correlate with higher systolic pressures and albuminuria in Greyhounds. Plasma aldosterone concentration was significantly lower in Greyhounds versus non‐Greyhounds (11, 11–52 vs 15, 11–56 pg/mL, respectively, P = .002).

Conclusions and clinical importance

Basal RAAS activation did not differ between healthy Greyhounds and non‐Greyhounds. Lower aldosterone concentration in Greyhounds is an appropriate physiologic response to higher serum sodium concentration and blood pressure, suggesting that angiotensin II effects in the renal tubule predominate over those of aldosterone.

Plasma Vasoprotective Eicosanoid Concentrations in Healthy Greyhounds and Non-Greyhound Dogs

BACKGROUND

Hypertension and albuminuria often coexist in Greyhounds, suggesting generalized vascular dysfunction that could contribute to the development of a variety of diseases in this breed. Eicosanoid metabolites of arachidonic acid (AA) mediate endothelial function, vascular reactivity, and proteinuria in humans and in rodent models.

HYPOTHESIS

The eicosanoid profile of Greyhounds is shifted toward metabolites that promote vascular dysfunction, hypertension, and proteinuria.

ANIMALS

Healthy Greyhounds (n = 20) and non-Greyhound (n = 20) dogs that were consecutively enrolled in a blood donor program.

METHODS

Prospective study. Plasma eicosanoid metabolites were assayed by liquid chromatography/electrospray ionization mass spectrometry (LC/ESI/MS) and compared to systolic blood pressure (SP) measurements and urine albumin concentration.

RESULTS

Isomers of hydroxyeicosatetraenoic acid (HETE) were higher in Greyhounds than non-Greyhounds (median, range in pmol/mL: 5(S)HETE 19.82, 8.55-32.95 versus 13.54, 4.33-26.27, P = .033; 8(S)HETE 9.39, 3.28-19.84 versus 5.80, 2.25-17.66, P = .002; 9(S)HETE 9.46, 2.43-13.79 versus 5.82, 1.50-17.16, P = .026; 12(S)HETE 10.17, 3.81-40.06 versus 7.24, 2.9-16.16, P = .022). Dihydroxyeicosatrienoic acid (DHET) isomers also were higher in Greyhounds compared to non-Greyhounds (mean ± SD in pmol/mL: 8,9DHET 5.78 ± 2.13 versus 4.03 ± 1.36, P = .004; 11,12DHET 11.98 ± 2.86 versus 8.90 ± 3.48, P = .004; 14,15DHET 7.23 ± 2.19 versus 5.76 ± 1.87, P = .028). Albuminuria correlated with total DHET (rs = 0.46, P = .003). SP was positively correlated with 11,12EET (rs = 0.42, P = .006) and 20(S)HETE (rs = 0.38, P = .017). SP and 8,9EET were inversely correlated (rs = -0.49, P = .001).

CONCLUSIONS AND CLINICAL IMPORTANCE

Plasma eicosanoid profile in Greyhounds was consistent with activation of metabolic pathways known to promote vascular dysfunction and might contribute to higher blood pressures and albuminuria. Inhibition of these eicosanoid pathways should be evaluated as therapeutic targets in Greyhounds.

Treatment of Obese Female and MaleSHHF/Mcc-facpRats with Antihypertensive Drugs, Nifedipine and Enalapril: Effects on Body Weight, Fat Distribution, Insulin Resistance and Systolic Pressure

Little is known about the effects of common antihypertensive drugs in obese, insulin-resistant females. Nine-month-old obese female SHHF/Mcc-fa(cp) rats that received either nifedipine, a calcium channel antagonist, or enalapril, an angiotensin-converting-enzyme inhibitor, for three months were compared with untreated SHHF/Mcc-fa(cp) rats (controls). After one month, nifedipine significantly decreased body weight in obese females compared to either enalapril or controls. After three months of treatment, total, abdominal, and subcutaneous fat masses were decreased in obese females given nifedipine compared to either enalapril or controls. Enalapril treatment was associated with a redistribution of fat mass from abdominal to subcutaneous depots. Nifedipine reduced plasma triglyceride and fasting glucose levels and improved insulin response to an oral glucose load in obese females, whereas enalapril did not appear to affect glycemic control. Systolic pressure was not significantly decreased until after two months of treatment with nifedipine or three months of treatment with enalapril in obese females and may have coincided with improvement in insulin-resistance. Similarly, plasma atrial natriuretic peptide concentrations were significantly lower in obese females given nifedipine. To determine how obese males responded to a calcium channel antagonist, six-month-old obese male SHHF/Mcc-fa(cp) rats were treated for three months with either nifedipine or placebo (controls). Nifedipine-treated obese males showed a mild but significant decrease in weight gain that was due to a decrease in fat deposition in both subcutaneous and abdominal depots and systolic blood pressure was significantly reduced after one month of treatment. Nifedipine did not affect other plasma biochemical parameters in obese males. In conclusion, nifedipine improved systolic pressure and glycemic control in obese female SHHF/Mcc-fa(cp) rats, effects that may be associated with a marked loss in body weight and fat mass and improved lipid metabolism. Nifedipine-treated obese males exhibited only a diminished weight gain that was not associated with changes in diabetic characteristics.

Response: persistent perplexities

This response to the preceding five articles highlights the stubborn persistence of the philosophical perplexities surrounding commodification in the realm of medicine and biotechnology.

Obese female SHHF/Mcc-fa(cp) rats resist antihypertensive effects of renin-angiotensin system inhibition

Gender and obesity may influence response to pharmacological modulation of the renin-angiotensin system. We used SHHF/Mcc-fa(cp) rats to study effect of obesity and gender on the ability of an AT1 receptor antagonist to decrease blood pressure. After 2 weeks treatment with irbesartan (50 mg/kg), only lean and obese males showed significant decreases in blood pressure, while obese females were completely resistant. Lean females showed a trend toward lowering of pressure (p=0.06). However, irbesartan similarly shifted angiotensin II dose response curves to the right in all groups. Twelve weeks of irbesartan also failed to decrease blood pressure, but did significantly reduce heart weight in obese females. In untreated rats, obese females had lower plasma renin activity and serum angiotensin converting enzyme activity compared to lean males, while lean and obese females had increased urinary endothelin excretion. Despite an otherwise similar genetic background contributing to hypertension and heart failure, obese females have different patterns of humoral activation compared to lean males, which may contribute to their resistance to the depressor effects of irbesartan.

Effect of ovariectomy and estrogen replacement on cardiovascular disease in heart failure-prone SHHF/Mcc- fa cp rats

The importance of endogenous and exogenous estrogen levels to the development of cardiovascular disease in women in controversial. The purpose of our study was to examine the effect of estrogen on the development of hypertension, cardiac hypertrophy, ventricular function, and gene expression for atrial natriuretic peptide (ANP) and components of the renin angiotensin system in spontaneously hypertensive heart failure rats (SHHF/Mcc- facp). Development of hypertension was prevented in 3-month-old ovariectomized rats receiving subcutaneous 17 beta -estradiol implants (EST) compared to ovariectomized (OVX) and controls (CON). EST had the least left ventricular hypertrophy, CON were intermediate, and OVX had the most (P<0.05), correlating well with systolic blood pressure. OVX had significantly lower percentage V(1)myosin isoform compared to EST and CON, indicating reversion to a more immature phenotype associated with hypertrophy. Similarly, OVX had decreased percentage left ventricular shortening fraction by echocardiography compared to EST and CON. These changes were not accompanied by alterations in plasma ANP, or in expression of mRNA for left ventricular ANP, renal renin, or hepatic angiotensinogen. Serum angiotensin converting enzyme activity was lower in EST compared to CON or OVX. When 17 beta -estradiol was given to 17-month-old rats that had naturally ceased estrous cycling, there was no effect on hypertension, progression of cardiac functional decline, or survival. In conclusion, estradiol treatment given prior to the development of hypertension in SHHF prevented left ventricular hypertrophy and hypertension. Development of congestive heart failure was not delayed if 17 beta -estradiol was begun in the post-menopausal period. Effectiveness of estrogen therapy may depend on age or whether hypertension is already established at the time treatment is begun.

Comparison of verapamil and felodipine treatment on lipid and glucose metabolism in obese female SHHF/Mcc-facp rats

Calcium channel blockers, verapamil or felodipine, were given to genetically obese 6 and 11-month-old female SHHF/Mcc-facp (SHHF: Spontaneous Hypertension Heart Failure) rats for 8 weeks to investigate their effects on glucose and lipid metabolism and obesity. Both antihypertensive agents significantly decreased systolic blood pressure. In 11-month-old rats, verapamil treatment significantly decreased body weight after 4 weeks whereas with felodipine it was only significantly reduced after 8 weeks. In 6-month-old rats, verapamil significantly curtailed body weight gain. Subcutaneous fat depots were smaller, and abdominal fat depots were larger in verapamil rats compared to felodipine or control rats. Oral glucose tolerance tests in the 6-month-old verapamil and the 11-month-old felodipine groups showed improved glucose tolerance compared to their respective control groups. After 8 weeks of treatment, fasting plasma glucose levels were lower in 6-month-old verapamil rats compared to felodipine and control rats and were decreased by both verapamil and felodipine treatments as compared to control in 11-month-old rats. During the oral glucose tolerance test in 6-month-old rats, both fasting plasma insulin and the area under the insulin curve were increased in verapamil compared to both control and felodipine groups. When compared to controls, plasma cholesterol was increased by verapamil in both age groups, but was significantly decreased by felodipine after 8 weeks of treatment in the 11-month-old group. Plasma triglycerides increased in all control rats compared to initial levels; however, verapamil and felodipine groups showed lower triglycerides in both age groups. In 6-month-old rats, the percentages of plasma HDL significantly increased in both treatment groups as compared to control. This study shows that verapamil and felodipine depressed body weight gain in the young rats, reduced body weight in the old rats, improved lipid parameters and glucose tolerance, but had the opposite effects on body fat distribution and insulin levels in obese female SHHF rats.

Comparison of irbesartan with captopril effects on cardiac hypertrophy and gene expression in heart failure-prone male SHHF/Mcc-fa(cp) rats

Angiotensin-converting enzyme (ACE) inhibitors have proven an effective means to control hypertension and manage cardiac hypertrophy. It is presently unknown if newer specific angiotensin II subtype 1 receptor (AT1R) antagonists are as effective or more effective in treating these conditions compared with ACE inhibitors. There is evidence that these classes of drugs may affect cardiac hypertrophy by different mechanisms. This study compared the effect of irbesartan, an AT1R antagonist, with that of captopril, an ACE inhibitor, on expression of early genetic markers of cardiac hypertrophy in lean male SHHF/Mcc-fa(cp) rats. SHHF/Mcc-fa(cp) rats (n = 10/group) were given captopril (100 mg/kg/day), irbesartan (50 mg/kg/day), or placebo for 16 weeks. Irbesartan and captopril significantly reduced systolic pressure and produced similar rightward shifts in the angiotensin I dose-response curve. Renal renin gene expression was increased 8.6-fold by irbesartan and 17.7-fold by captopril. The only effect on echocardiographic findings was a similar decrease in aortic peak velocity, an index of systolic function, by both treatments. Early markers of cardiac hypertrophy were significantly attenuated by both drugs. Both drugs produced marked and equivalent reductions in left ventricular atrial natriuretic peptide (ANP) messenger RNA (mRNA) levels compared with controls. This decrease in ANP gene expression was accompanied by a decrease in plasma ANP concentration in the treatment groups. The shift from V1 to V3 myosin isozymes was similarly decreased in both treatment groups, compared with controls. These data suggest that captopril and irbesartan are similarly effective in controlling expression of genes associated with ventricular hypertrophy in heart failure-prone SHHF/Mcc-fa(cp) rat.

Effect of ovariectomy in heart failure-prone SHHF/Mcc-facp rats

The importance of the loss of ovarian function to the progression of hypertension and heart disease in women is controversial. We investigated whether ovariectomy would accelerate development of hypertension, congestive heart failure, and neurohumoral activation in adult spontaneous hypertension heart failure (SHHF) rats, a genetic model of heart failure. Six months after ovariectomy, no significant differences between control and ovariectomized rats were seen in systolic or diastolic blood pressure, left ventricular fractional shortening by echocardiography, or heart weight. Percent V1 myosin isozyme was significantly lower in ovariectomized rats. Northern blot analysis failed to show significant differences between groups in expression of hepatic angiotensinogen, renal renin, or left ventricular atrial or brain natriuretic peptide mRNA. In a second experiment, serial measures of systolic pressure and left ventricular shortening fractions failed to document a significant difference between control and ovariectomized rats as they developed heart failure, although there was a significant decline in shortening fraction in both groups at the age when regular estrous cycling naturally ceases. Survival time was similar between groups. In summary, ovariectomy of adult SHHF rats does not appear to affect the progression of genetically programmed hypertension and heart failure in this model.

Muscle potassium content and potassium gluconate supplementation in normokalemic cats with naturally occurring chronic renal failure

Muscle potassium content and supplementation with potassium gluconate were evaluated in normokalemic cats with chronic renal failure (CRF). Affected cats received standard medical therapy for renal failure and either placebo (sodium gluconate) or potassium gluconate. At the beginning of the study and after 6 months of supplementation, glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were estimated using 3H-inulin and 14C-tetraethylammonium bromide (TEA) clearances. Muscle potassium content was determined in biopsy specimens using atomic absorption spectroscopy. Muscle biopsy samples obtained from cats with CRF before treatment had significantly lower muscle potassium content than did those from normal control cats. Over the 6-month period of supplementation, muscle potassium content increased both in cats with CRF that received potassium gluconate and in those that received placebo (sodium gluconate). Serum potassium concentration and fractional excretion of potassium remained relatively unchanged in both groups of cats throughout the treatment period. There were no significant differences in the percentage change in GFR and ERPF between treatment groups over the 6-month time period. Median values for pH, HCO3-, and total CO2 at 6 months were higher than baseline in the potassium gluconate group but lower than baseline in the sodium gluconate group.

Verapamil accelerates the transition to heart failure in obese, hypertensive, female SHHF/Mcc-fa(cp) rats

We sought to characterize the effects of the nonselective Ca2+ channel antagonist, verapamil, and the vascular-selective Ca2+ channel antagonist, felodipine, on obese, hypertensive, heart failure-prone, female SHHF/Mcc-fa(cp) rats. Rats were treated for < or = 2 months with verapamil (57 mg/kg/day) or felodipine (24 mg/kg/day). Blood pressures were determined at monthly intervals by the tail-cuff method. Heart weights and myosin isoforms were measured at the end of treatment. Direct cardiac effects of verapamil and felodipine were examined in electrically field stimulated, fura-2/AM-loaded cardiomyocytes. Both Ca2+ channel antagonists reduced systolic blood pressures. Verapamil, but not felodipine, increased heart weights and decreased expression of the myosin V1 isoform. In older animals, 75% of those treated with verapamil developed end-stage congestive heart failure. Age-matched control and felodipine-treated rats remained healthy. In isolated cardiomyocytes, 10(-9) M verapamil significantly reduced Ca2+ transient amplitudes but 10(-9) M felodipine did not. Both Ca2+ channel antagonists reduced blood pressures in obese, hypertensive, female SHHF rats. Verapamil, but not felodipine, produced heart failure in a large number of these animals. Differences between the in vivo effects of the two Ca2+ channel antagonists may be related to the differing effects on sarcolemmal Ca2+ influx.

Autosomal dominant polycystic kidney disease in Persian and Persian-cross cats

A form of autosomal dominant polycystic kidney disease (ADPKD) similar in clinical features to human ADPKD occurs in the Persian cat. We characterized the morphologic and immunohistochemical features of this disease in a colony of affected cats. Complete postmortem examinations were performed on 11 normal and 22 affected cats ranging in age from 3 months to 10 years. Kidneys were evaluated by gross and histologic examinations, ultrastructure, lectin staining, bromodeoxyuridine immunochemistry for labeling index and immunochemistry for distribution of Na/K ATPase. Feline ADPKD was characterized by variable numbers of cysts in the renal cortex and medullar. Ultrastructural examination and lectin staining suggested that cysts arose from proximal and distal nephron segments. Bromodeoxyuridine labeling demonstrated increased proliferation of epithelium lining some cysts in young cats. Immunohistochemical staining showed variable translocation of Na/K ATPase from the basolateral membranes of cyst-lining cells to the cytoplasm or luminal membranes. Cystic renal disease commonly was associated with chronic tubulointerstitial nephritis and hepatobiliary hyperplasia and fibrosis. Focal hyperplasia of renal tubular epithelium, hepatic cysts, and cardiac lesions were present in some cats. Feline ADPKD shares many morphologic and pathogenetic features with human ADPKD.

Renal function and organic anion and cation transport during dehydration and/or food restriction in chickens

The effect of dehydration in the presence or absence of continued food intake on renal function was evaluated in chickens. In addition, renal transport of organic anions and cations under these conditions was assessed in vitro by uptake of 14C-para-aminohippuric acid and 14C-tetraethylammonium bromide by renal slices. Water restriction with continued food intake resulted in increases in serum osmolality and serum concentrations of sodium, uric acid, calcium and total protein. If food was restricted in addition to water, only serum osmolality and sodium concentration were significantly increased after 48 hours. Dehydration with continued access to food resulted in marked decreases in extracellular fluid volume, glomerular filtration rate and effective renal plasma flow. If food was restricted during dehydration, the decrease in effective renal plasma flow was attenuated despite reductions in glomerular filtration rate and extracellular fluid comparable to that seen in dehydrated birds allowed free access to food. Transport of organic anions was significantly increased after 24 and 48 hours of water restriction, regardless of whether food was withheld. Enhanced transport of organic anions in the presence of decreased glomerular filtration rate and effective renal plasma flow during dehydration may promote precipitation of urates and nephrosis in chickens.

Inheritance of polycystic kidney disease in Persian cats

Polycystic kidney disease in Persian cats culminates in chronic renal failure after a variable clinical course. An affected 6-year-old Persian cat was used to establish a colony of cats with polycystic kidney disease. In affected cats, cysts could be detected by ultrasonography as early as 7 weeks of age. Absence of cysts on ultrasound examination at 6 months of age was correlated with absence of polycystic kidney disease at necropsy. Both males and females were affected and, of progeny from affected x unaffected crosses, 42% were affected and 58% were unaffected. In affected x affected crosses, 73% of progeny were affected and 27% were unaffected. These results are compatible with autosomal dominant inheritance of this trait. Polycystic kidney disease in Persian cats resembles autosomal dominant polycystic kidney disease (ADPKD) in human beings, and represents a valuable animal model of the human disease.

An animal model of gastric ulcer due to bacterial gastritis in mice

Conventional female BalbC mice were inoculated with Gastrospirillum-like bacteria in mouse gastric homogenate or in 5.0-microns filtrate of gastric homogenate. The bacteria were originally isolated from cheetahs with gastritis. The mice were killed 6 months, 7 months, or 1 year after inoculation. All mice became infected with Gastrospirillum-like bacteria that were confined to the gastric mucosa. Control mice, given either sterile Brucella broth, 0.22-microns filtrate of infected gastric homogenate, or uninfected gastric homogenate did not become infected with bacteria. Lesions in infected mice included severe lymphoplasmacytic gastritis (26/26 infected mice), gastric epithelial hyperplasia (25/26 infected mice), and gastric ulceration (11/26 infected mice). Neutrophilic inflammatory cell infiltrates were inconsistent. None of the uninfected control mice had Gastrospirillum-like bacteria, gastritis, gastric epithelial hyperplasia, or gastric ulceration. These results implicate Gastrospirillum-like bacteria from cheetahs in the pathogenesis of gastric ulceration. This model will be useful in investigating the mechanisms of gastric ulceration associated with bacterial gastritis.

Acute renal failure as the cause of death in chickens following intravenous inoculation with avian influenza virus A/chicken/Alabama/7395/75 (H4N8)

One-day-old and 5-week-old commercial leghorn, specific-pathogen-free leghorn, and broiler chickens were inoculated intravenously with either avian influenza virus isolate A/chicken/Alabama/7395/75 (H4N8) (Ck/AL) or sterile diluent. Ck/AL infection resulted in a 44% mortality rate, reduced weight gains, and necrosis of proximal renal tubules and/or tubulointerstitial nephritis. The renal tubule necrosis was more severe and widespread in chickens that died than in chickens that were euthanatized. Hyperuricemia, hypercalcemia, and hyperphosphatemia were present in 5-week-old chickens at day 5 postinfection. Influenza virus isolate Ck/AL was nephropathogenic, and death was associated with acute severe renal damage and failure. Some data suggested that the pathogenicity of Ck/AL may be more severe in leghorns than broilers.

Use of a single injection solute-clearance method for determination of glomerular filtration rate and effective renal plasma flow in chickens

A single-injection clearance method for determining glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) in chickens was compared with the continuous-infusion method. Male and female White Leghorn chickens were anesthetized, and catheters were placed in both brachial veins and over both ureteral openings. A single-bolus injection of 3H-inulin and 14C-para-aminohippuric acid was given at a dose of 1.0 microCi of each solute per kg of body weight and nine blood samples were obtained over 60 min. After the last sample was taken, the birds were given a bolus injection of 1 microCi of 3H-inulin/kg and 1 microCi of 14C-para-aminohippuric acid/kg, followed by a constant infusion of 0.1 microCi of each solute/min at a rate of 0.1 ml.kg-1 x h-1. Following a 45-min stabilization period, three continuous urine collections were performed. A blood sample was obtained at the midpoint of each urine collection. The GFR and ERPF determined by the single-injection method (3.12 +/- 0.43 and 22.81 +/- 3.48 ml.min-1 x kg-1, respectively) were comparable to values for the continuous-infusion method (2.81 +/- 0.35 and 22.88 +/- 4.03 ml.min-1 x kg-1, respectively). Both GFR and ERPF determined by the single-injection method correlated with GFR and ERPF determined by the continuous-infusion method. This single injection method provides a rapid, accurate method for determining GFR and ERPF in chickens and eliminates the need for collection of urine.

Animal models of bacterial gastritis: the role of host, bacterial species and duration of infection on severity of gastritis

Gastric bacteria from cheetahs with gastritis were used to inoculate specific-pathogen free kittens and conventional mice. Helicobacter sp. and Gastrospirillum sp. colonized kittens, while only Gastrospirillum sp. colonized mice. In kittens, both bacterial species induced mild lymphofolliclar gastritis which did not change over the course of the 11 months observation period. In mice, Gastrospirillum sp. induced lymphoplasmacytic and follicular gastritis which increased in severity over 6 months and persisted for the 12 month observation period. Gastric ulcers and gastric mucosal hypertrophy were present in chronically infected mice. These results indicate that host but not bacterial factors influence the severity of gastritis, and that in mice, bacterial gastritis increases in severity with time and may lead to gastric ulceration in some individuals.

Effects of vitamin A deficiency on the reproductive system of mature White Leghorn hens

Two groups of 100 white leghorn hens were fed rations either supplemented or deficient in vitamin A for 32 weeks. At the conclusion of the study, vitamin A-supplemented hens laying normally were also compared with a group of vitamin A-supplemented hens in a state of low egg production. Mean egg retinol equivalents (microgram retinol/g egg yolk), egg production, and hatchability in the vitamin A-deficient group were decreased significantly by 4, 20, and 28 weeks, respectively, after beginning treatment. The ovaries of vitamin A-deficient chickens had increased numbers of atretic follicles compared with the ovaries of vitamin A-supplemented hens (20, 24, 28, and 32 weeks), and these atretic follicles contained moderate to severe hemorrhage. Hemorrhage was located either uniformly throughout the follicle or more commonly between the detached granulosa cell layer and the theca interna. Hemorrhagic follicles were uncommon in both vitamin A-supplemented hens and low-production vitamin A-supplemented hens.

The effect of atrial natriuretic peptide infusion on renal haemodynamics and plasma lipoproteins in puromycin aminonucleoside nephrosis in rats

1. The effect of continuous intravenous administration of 1 microgram/h atrial natriuretic peptide (ANP) for 4 days was studied in normal male Sprague-Dawley rats and rats made nephrotic with puromycin aminonucleoside (PA). 2. ANP infusion significantly increased urinary sodium and potassium excretion by 3 days of infusion in control rats but not in PA-treated rats. ANP infusion significantly increased glomerular filtration rate in PA-treated rats, while effective renal plasma flow was similarly decreased compared with non-infused nephrotic rats. 3. Plasma high density lipoproteins (HDL) were significantly decreased and low density lipoproteins (LDL) were increased in PA-treated rats that received ANP; HDL were increased in normal rats infused with ANP. 4. Competitive binding studies demonstrated a lower density of specific ANP receptors in glomerular membranes from rats injected with PA, while binding affinity was unchanged. 5. Infusion with exogenous ANP did not promote natriuresis in PA nephrosis despite an enhancement of glomerular filtration rate (GFR), thus suggesting that sodium retention in this model is due to a post-glomerular defect. Plasma lipoprotein composition in both normal and nephrotic rats may be affected by ANP.

Helicobacter acinonyx sp. nov., isolated from cheetahs with gastritis

Four strains of a novel Helicobacter species were isolated from the stomachs of cheetahs (Acinonyx jubilatus) with gastritis. These isolates were phenotypically similar to Helicobacter pylori. The isolates were gram-negative, spiral bacteria which grew under microaerophilic conditions at 37 degrees C, but not at 25 or 42 degrees C, and produced urease, catalase, oxidase, alkaline phosphatase, and gamma-glutamyl transpeptidase. The isolates did not ferment glucose, mannitol, inositol, sorbitol, rhamnose, sucrose, melibiose, amygdalin, or arabinose; hydrolyze hippurate or indoxyl acetate; or reduce nitrate. They did not produce H2S from triple sugar iron agar, and they did not grow in the presence of 1.0% glycine or 1.5% NaCl. They were resistant to nalidixic acid and sensitive to cephalothin and metronidazole. Cells were typically 0.3 by 2.0 microns and possessed tufts of two to five sheathed, monopolar flagella. The G+C content of strain 90-119 was 30 mol%. Cluster analysis of densitometry scans of polyacrylamide protein gels revealed more than 70% similarity of the cheetah isolates to H. pylori, less than 60% similarity to Helicobacter felis, and less than 50% similarity to Helicobacter mustelae. Complete 16S rRNA sequences were determined for two of the cheetah isolates. Phylogenetic analysis was performed by comparing the cheetah sequences to those of 19 reference strains, including H. pylori, H. felis (two strains), H. mustelae, Helicobacter muridarum, "Flexispira rappini," Wolinella succinogenes, Campylobacter coli, Campylobacter concisus, Campylobacter curvus, Campylobacter fetus, Campylobacter hyointestinalis, Campylobacter jejuni, Campylobacter lari, Campylobacter rectus, Campylobacter sputorum subsp. bubulus, a Campylobacter sp. (pig isolate), [Bacteroides] gracilis, and [Bacteroides] ureolyticus.(ABSTRACT TRUNCATED AT 250 WORDS)

Epizootic gastritis associated with gastric spiral bacilli in cheetahs (Acinonyx jubatus)

An outbreak of vomiting in a group of captive cheetahs (Acinonyx jubatus) was investigated, and histologic examination revealed chronic gastritis characterized by infiltration of lymphocytes and numerous plasma cells and epithelial erosions. Lymphoid follicles, globule leukocytes, scattered neutrophils, and (in one animal) abscessed gastric glands were inconsistent findings. In addition, necropsy of three cheetahs revealed gastric mucosal hyperplasia. Two kinds of bacteria were identified in the stomachs of infected cheetahs. Numerous long, tightly coiled motile Gastrospirillum-like organisms were seen in gastric mucus and in Warthin-Starry-stained sections of mucosa. These bacteria could not be cultured but were transmitted to conventional mice in homogenates of gastric mucosa from infected cheetahs. Ultrastructural examination revealed helical filaments on some of these bacteria. In addition, a smaller Helicobacter sp. was isolated. This organism could be cultured in vitro under microaerophilic conditions. One or both of these bacterial species was probably responsible for the gastritis in these cheetahs.

Effects of enalapril and clonidine on glomerular structure, function, and atrial natriuretic peptide receptors in SHHF/Mcc-cp rats

Seven-month-old, lean male SHHF/Mcc-cp rats, a model of spontaneous hypertension, progressive renal dysfunction, and congestive heart failure (CHF), were treated with either clonidine (CL) or enalapril (EN) or received no treatment (CON) for 20 weeks. CL significantly decreased systolic blood pressure (SBP), kidney weights, and severity of renal lesions as compared with untreated CON. EN produced a decrease in SBP comparable to that in CL. Kidney weights and severity of renal histologic changes in the EN group were intermediate between those of the CL and CON groups. Despite similar plasma atrial natriuretic peptide (ANP) concentrations, CL treatment resulted in a significant increase in the density of guanylate cyclase-linked glomerular ANP receptors, whereas EN treatment resulted in a significant decrease in the total number of ANP receptors and in the number of nonguanylate cyclase-linked receptors and an increase in overall binding affinity. These findings demonstrate that antihypertensive agents will slow progression of renal injury in SHHF/Mcc-cp rats and that CL is more effective than EN in alleviating progressive kidney damage in this model. Furthermore, different classes of antihypertensive drugs may alter the density or ratio of biologically active and clearance ANP receptor sites in the glomerulus.

Gastric spiral bacilli in captive cheetahs

Two kinds of gastric spiral bacilli were identified in the stomachs of captive cheetahs with naturally occurring gastritis. One type was morphologically similar to 'Gastrospirillum hominis'. This organism could not be cultured in vitro. Some of these bacteria had superficial helical filaments, and others did not. The other type was morphologically, biochemically, and bacteriologically similar to Helicobacter pylori. This organism is most likely a new species of Helicobacter. One or both of these bacteria may have been responsible for the gastritis seen in these cheetahs.

Helicobacter pylori gastric infection in gnotobiotic beagle dogs

Establishment of infection with Helicobacter pylori and gastritis in nonhuman species is currently only successful in gnotobiotic piglets. This study was designed to determine whether H. pylori will colonize the gastrointestinal tract of gnotobiotic dogs. Gnotobiotic beagle pups were derived by standard methods. Group A (five dogs) was orally challenged with 3 x 10(8) H. pylori at 7 days of age. Group B (two dogs) received only peptone water but was contact-exposed beginning on day 23 postinfection (p.i.). Necropsy was performed on dogs on day 30 p.i. H. pylori colonized the stomach of all dogs (groups A and B). Urease map analysis correlated with the microbiologic findings and indicated that the density of colonization was less than that observed in human tissue. Organisms were also recovered from the pharynx, esophagus, duodenum, and rectum of 1, 2, 2, and 1 dog, respectively. All group A and one group B dog developed serum immunoglobulin G specific for H. pylori by day 30 p.i. Gross lesions were restricted to the stomach and consisted of small (less than 1 mm) lymphoid follicles. Microscopically, there were focal to diffuse lymphoplasmacytic infiltrates with follicle formation and mild to moderate infiltration of neutrophils and eosinophils in the gastric lamina propria. With the Warthin-Starry silver stain, organisms were seen on the surface of the gastric epithelial cells, beneath the mucus layer. We conclude that H. pylori colonizes the stomachs of gnotobiotic dogs for at least 1 month and the lesions resemble those seen in humans. H. pylori is transmissible by contact from infected to noninfected dogs.

Enteric disease in specific-pathogen-free turkey poults inoculated with a small round turkey-origin enteric virus

Four- and 5-day-old specific-pathogen-free turkey poults were inoculated orally or by contact exposure to a small round turkey-origin enteric virus. At days 4 and 8 postinoculation (PI), the orally inoculated poults had significantly lower body weight gains than control poults. Poults at day 4 (orally inoculated) and 5 (contact-exposed) PI had watery droppings, dilated thin-walled ceca filled with yellow foamy fluid, catarrhal small intestinal secretions, pale intestinal serosa, and mild lymphocytic enteritis. In addition, at day 4 PI, poults were lymphopenic, had intracytoplasmic crystalline arrays of 17.1 +/- 1.1 nm viral particles in the jejunal villar enterocytes, and had an 18-to-24-nm virus in intestinal contents. Analysis of morphometric data revealed mild shortening of villi in the duodenum and elongation of crypts in the duodenum and ileum during the late stage of the syndrome (day 8 PI). These findings suggest that the 18-to-24-nm virus can produce an enteric disease syndrome and that the acute clinical manifestation of this syndrome is not the result of morphologic change such as intestinal villus atrophy. The definitive identity of this 18-to-24-nm virus is not known; however, based on size and intracytoplasmic arrays of virus, it is most probably an enterovirus.

Dose effect of captopril on renal hemodynamics and proteinuria in conscious, partially nephrectomized rats

The effect of varying doses of captopril, an angiotensin I-converting enzyme inhibitor, on renal hemodynamics, systemic arterial pressure, and the progression of chronic renal disease in conscious, three-quarter nephrectomized adult male Sprague-Dawley rats was studied. Six weeks following nephrectomy (Week 0), rats were randomly divided into five groups. Group 2 (n = 8), 3 (n = 8), 4 (n = 9), and 5 (n = 5) were given 5, 10, 20, and 40 mg/kg captopril, respectively, daily in drinking water. Group 1 (n = 7) and sham-operated controls (n = 7) were given water only. On Weeks -6, 0, 2, and 4, renal function was assessed by 24-hr urinary protein excretion and plasma creatinine. Systolic blood pressure was measured at these times by the tail cuff method. Following Week 4, glomerular filtration rate and effective renal plasma flow were measured in conscious rats by single injection clearance of [3H]inulin and [14C]tetraethylammonium bromide, respectively. Group 1 had significantly higher (P less than 0.05) 24-h urinary protein excretion, plasma creatinine, and systolic pressure compared with Group 5 and controls by Week 4, whereas values for these parameters for Groups 2-4 ranged between these extremes. Although systolic pressures were not significantly different (P greater than 0.05), Group 2 had significantly lower proteinuria than Group 1 (P less than 0.05) at Week 4. Total kidney glomerular filtration rate was similarly decreased in Groups 1-5 compared with control rats. Total kidney effective renal plasma flow was higher in captopril-treated groups than in Group 1, whereas systolic blood pressure was similar or lower, indicating that captopril reduced renal vascular resistance. Furthermore, unlike Groups 1-3, the groups receiving higher doses of captopril (4 and 5) did not develop anemia associated with chronic renal disease. In conclusion, captopril attenuated renal functional deterioration in a dose-related manner. The effect on proteinuria was evident at low doses of captopril which did not significantly reduce systemic blood pressure and was accompanied by an increase in effective renal plasma flow and a decrease in renal vascular resistance.

Choosing family law over contract law as a paradigm for surrogate motherhood

Among the many new forms of human reproduction, none raises more problems of public policy and of law than the practice of what is known, rather inaccurately, as surrogate motherhood or surrogacy. The central policy issue is settling on the paradigm that should govern surrogate motherhood, a model of family relations (adoption) or of contractual relations (sale of a product or service). And the central legal issue is whether any restrictions on personal choice that follow from the policy selected—and especially from a rejection of the contractual model with its implication of free choice—are constitutionally permissible.

We conclude that surrogate mother arrangements should be handled from the perspective of adoption. As recent judicial decisions have demonstrated, existing law on parents and children is largely adequate, and the emergence of surrogacy as a social practice does not require major law reform efforts. Furthermore, neither these rulings nor legislation proposed in many jurisdictions to ban commercialized surrogacy intrude impermissibly on the range of choices about reproduction protected by the Constitution of the United States.

Effect of propranolol on progression of chronic renal disease in partially nephrectomized rats

The effect of propranolol, a beta adrenergic receptor blocking agent, on the progression of renal dysfunction in three-quarters nephrectomized adult male Sprague-Dawley rats was studied. Beginning four weeks after partial nephrectomy (week 0), rats received either 50 mg/kg propranolol (Group I) or distilled water (Group II) daily by gavage for 12 weeks. Renal function was measured by 24 hour urinary protein excretion, water intake, urine output, plasma creatinine, and plasma urea nitrogen at weeks -4, 0, 4, 8, and 12. Mean systolic blood pressure was measured by the tail cuff method. At the end of 12 weeks, rats were euthanatized, and remnant kidneys examined histologically. Group II rats were significantly (p less than 0.05) proteinuric compared to Group I rats at weeks 8 and 12. Mean systolic blood pressures of Group II rats were significantly greater (p less than 0.05) than group I rats on week 8. Both groups became significantly hypertensive (p less than 0.05) compared to week 0 values by week 12. Group II had significant (p less than 0.05) polyuria, polydipsia, and elevated plasma creatinine and urea nitrogen compared to Group I at week 12. Groups I and II could not be distinguished on the basis of renal histologic rank (p = 0.104). We conclude that propranolol attenuated the progression of chronic renal disease in this model.

Povidone-iodine lavage treatment of experimentally induced equine infectious arthritis

Both tarsocrural joints of 4 horses were inoculated with 1.5 X 10(5) colony-forming units of Staphylococcus aureus. On days 1, 3, and 6, each horse had one tarsocrural joint lavaged with a balanced electrolyte solution and had the contralateral tarsocrural joint lavaged with 0.1% povidone-iodine solution. All horses were orally administered trimethoprim (5 mg/kg)/sufadiazine (25 mg/kg) combination twice daily and phenylbutazone (2 g) once daily for the duration of the study (21 days). On days 0, 1, 3, 6, 9, 14, and 21, synovial fluid specimens were collected and analyzed for color, clarity, total protein concentration, WBC count and differential, and mucin clot-forming ability. Synovial fluid specimens collected on days 1, 3, 6, 9, 14, and 21 were bacteriologically cultured. On day 21, all horses were euthanatized, the tarsocrural joints were opened and examined, synovial membrane specimens were collected, bacteriologically cultured, and histologically evaluated, and articular cartilage specimens were histochemically evaluated. Repeated measures analysis of variance were used to evaluate differences between lavage solutions and among days for objective measurements. A paired t test was used to evaluate differences between solutions for the indices of synovial membrane inflammation and articular cartilage staining intensity with safranin-O-fast green. To be considered significant, the probability of a type-I error was less than 0.05. Significant differences were not found between joints lavaged with electrolyte solution vs povidone-iodine solution for synovial total protein concentration, WBC count, results of synovial fluid and membrane bacteriologic culture, synovial membrane inflammation, or articular cartilage glycosaminoglycan concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of various treatments for experimentally induced equine infectious arthritis

To evaluate the effects of 5 treatments on clinical responses, synovial fluid analysis, radiographic changes, bacteriologic culture results of the synovial fluid and synovial membrane, microscopic characteristics of the synovial membrane, and articular cartilage histochemistry, Staphylococcus aureus organisms (1.6 X 10(6) colony-forming units) were inoculated into the tarsocrural joints of 12 horses (n = 24 joints; 2 joints/horse). Each horse was given phenylbutazone (2 g) orally, every 24 hours, beginning 24 hours after inoculation. Two horses (ie, 4 joints) were not given other treatment (controls; group 1). All other horses (ie, 20 joints) were given a trimethoprim-sulfadiazine combination orally, once daily (30 mg/kg; 8 joints) or twice daily (30 mg/kg q 12 hr; 12 joints). Each of these 20 joints were assigned to 1 of 5 treatment groups (4 joints/group) in a balanced incomplete block design. Group 2 (4 joints) was given only the antibiotics once daily. Twelve joints were treated by through-and-through joint lavage on day 1 (group 3), days 1 and 3 (group 4), or days 1, 3, and 6 (group 5). Joints in group 6 had an arthrotomy performed on day 1, with subsequent lavage via an indwelling drain every 12 hours for 4 days. In groups 3 through 6, 1 joint in each group was treated with antibiotics once daily, and 3 joints were treated with antibiotics twice daily. All horses were clinically assessed each day. Complete blood count was performed on days 3, 6, 10, and 21. Before inoculation and on days 0, 1, 3, 6, 10, and 21, synovial fluid specimens were collected and analyzed for color, clarity, total protein concentration, WBC count, differential count, and mucin clot-forming ability. Synovial fluid specimens were cultured bacteriologically before inoculation and on days 0 and 21. Horses in group 1 (controls) were euthanatized before day 6. All other horses were euthanatized on day 21. Tarsocrural joints were opened and examined. Synovial membrane specimens were bacteriologically cultured. Synovial membrane specimens were examined histologically (hemotoxylin and eosin stain) and articular cartilage specimens were (safranin O fast green stain) evaluated histochemically. Synovial membrane specimens were histologically graded into 5 categories. Intensity of articular cartilage intercellular staining with safranin 0 was graded for superficial, outer intermediate, inner intermediate, and deep zones. Two-way analysis of variance was performed to evaluate differences among groups and across time for the determinants evaluated.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of captopril on chronic puromycin aminonucleoside nephrosis in rats

The effect of captopril, an angiotensin converting enzyme inhibitor, on the progression of chronic puromycin aminonucleoside (PAN) nephrosis was examined. Rats were injected with 15 mg/100 gm body weight PAN and 5 mg/100 gm body weight, on weeks - 1 and 5, respectively. A third group was injected with an equivalent volume of 0.9% saline, intraperitoneally (Group III) on week - 1 and 5. Beginning week 0, group I received 50 mg/kg captopril daily in the drinking water for 12 weeks. Group II received no treatment. Captopril failed to attenuate the peak level of proteinuria induced by the first injection of PAN or to alter the rate of decline of proteinuria when begun 1 week after the PAN injection. However, captopril did blunt the increase in urinary protein excretion following the second injection of PAN (p less than 0.05). Group II became hypertensive compared to Group I on week 8 and 12 and Group III on week 12 (p less than 0.05). Group I and II could not be distinguished on the basis of renal histologic rank (p = 0.80). We conclude that captopril affords some protection against the development of PAN-induced proteinuria, but it does not accelerate the recovery phase when glomerular permselectivity is being regained.

Single-injection method for evaluation of renal function with 3H-inulin and 14C-tetraethylammonium bromide in conscious unrestrained Sprague-Dawley rats

A single-injection, double-isotope method for simultaneously determining glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) in conscious, unrestrained rats was evaluated. 3H-inulin and 14C-tetraethylammonium bromide were used to determine GFR and ERPF, respectively. Using a modified, single exponential, 1-compartment, mathematical model, solute clearance was estimated, using a plasma radioactivity disappearance curve constructed from samples collected during a 60-minute period. In 12 healthy, conscious, adult male Sprague-Dawley rats, the mean (+/- SEM) GFR, ERPF, and filtration fraction were 5.65 +/- 0.40 ml/min/kg, 13.92 +/- 0.82 ml/min/kg, and 0.41 +/- 0.03, respectively. In 7 adult male Sprague-Dawley rats that had undergone a three-quarter nephrectomy 6 weeks prior to study, the mean GFR, ERPF, and filtration fraction were 2.69 +/- 0.36 ml/min/kg, 7.02 +/- 0.90 ml/min/kg, and 0.39 +/- 0.03, respectively. In 37 adult male rats in various stages of renal disease, the mean GFR and ERPF correlated significantly (r = 0.85, P less than 0.001 and r = 0.83, P less than 0.001, respectively) with the reciprocal of plasma creatinine. The single-injection, double-isotope technique yielded functional values similar to those reported for healthy rats in which other clearance methods were used. Using this technique, we were able to detect alterations associated with various degrees of renal functional loss. The technique enabled us to evaluate conscious, unrestrained rats, eliminated the need to collect urine, and required short blood collection times (60 min) and small volumes (0.1 ml) of plasma.

Electronic measurement of erythrocyte volume and volume heterogeneity in horses during erythrocyte regeneration associated with experimental anemias

Anemia was induced in three groups of horses by moderate or severe acute hemorrhage, or by acetyl phenylhydrazine-induced hemolysis (Groups I, II, and III, respectively). Serial hemograms were done on a multichannel automated blood cell counter with histogram capability. Changes in hematocrit, mean cell volume, erythrocyte number, red cell distribution width (RDW), and standard deviation of erythrocyte volume were examined over time. Significant increases in mean cell volume were first detectable by days 17, 20, and 14 and reached maximum by days 43, 41, and 29, in Groups I, II, and III, respectively (P less than 0.05). Increased mean cell volume was interpreted as reflecting accelerated erythrocyte regeneration; however, not all horses with accelerated regeneration had changes in mean cell volume. Estimated erythrocyte production rate correlated poorly with hematocrit nadir and change in mean cell volume (r = 0.37 and r = 0.36, respectively, P greater than 0.05). In some horses effective regeneration occurs without development of macrocytosis. Mean cell volume remained increased after other parameters returned to control values, suggesting that mean cell volume values may provide retrospective evidence of altered erythrocyte turnover. Anisocytosis as indicated by significant increases in the standard deviation was greatest during the early part of the regenerative response, reaching maximum values on days 30, 28, and 21 in Groups I, II, and III, respectively, and began to decrease as homogeneous repopulation with macrocytes occurred. Red cell distribution width increased significantly only in severe hemorrhage and hemolysis groups, reaching mean maximum values of 24.3 on day 20 and of 26.4 on day 21 in Groups II and III, respectively (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Hematologic and serum biochemical values for Yucatan miniature swine

Hematologic and serum biochemical values were determined for healthy, mature Yucatan miniature swine, Sus scrofa. These values were similar to those reported for other breeds of swine. There was no effect on erythrocyte count, hematocrit, MCV, MCH, MCHC, RDW, platelet count, or leukocyte count attributable to sex (p greater than 0.05). Differential leukocyte counts generated on an automated multichannel blood cell counter, having a three part leukocyte differential capability, were compared to 100-cell manual leukocyte differentials. Determination of lymphocyte and non-lymphocyte fractions on this system were not significantly different from microscopic differentials (p less than 0.001). However, the mononuclear cell count did not correlate well with the percentage of monocytes determined manually (r = 0.084, p greater than 0.5). Leukocytes, erythrocytes, and platelets behaved properly with respect to counting thresholds as modified for counting cells of other common domestic species on this automated cell counter.

Single-injection method for evaluation of renal function with 14C-inulin and 3H-tetraethylammonium bromide in dogs and cats

A double-isotope single-injection method without urine collection for the estimation of glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) in dogs and cats was evaluated. The GFR was determined, using 14C-inulin and ERPF was determined, using [3H]tetraethylammonium bromide. Using a modified single exponential, 1-compartment mathematical model, the renal clearance of these solutes was estimated with a plasma radioactivity disappearance curve constructed from samples collected over a 150-minute time period. In 25 dogs, GFR, ERPF, and filtration fraction were 3.55 +/- 0.14 ml/kg/min, 10.51 +/- 0.72 ml/kg/min, and 0.34 +/- 0.02, respectively. In 25 cats, GFR, ERPF, and filtration fraction were 3.24 +/- 0.14 ml/kg/min, 8.14 +/- 0.53 ml/kg/min, and 0.39 +/- 0.02, respectively. This time-efficient and reliable method, using beta-emitting isotopes, yielded renal functional values well within the normal ranges reported by a variety of other isotopic and nonisotopic procedures. The advantages of the present procedure over previous double-isotope single-injection methods include the use of less costly, lower energy-using, and less penetrating beta emittors, as well as a shortened blood sampling schedule.