Biomedical subjects

R F Wideman

Publications and source records attributed to R F Wideman.

At least 109 records · Page 6Linked to original sources

PubMed1988

Effect of Gray strain infectious bronchitis virus and high dietary calcium on renal function of Single Comb White Leghorn pullets at 6, 10, and 18 weeks of age.

Experiments were designed to evaluate the effects of Gray strain infectious bronchitis virus (IBV) and high dietary calcium (Ca), alone and in combination, on renal function in pullets. Eight hundred female Single Comb White Leghorn chicks were raised on starter ration. Five hundred chicks were inoculated intravenously with Gray strain IBV at 4 wk of age; the remaining chicks were not exposed to IBV. At 6 wk of age, IBV-inoculated and uninoculated chicks were randomly divided into two diet treatment groups. Half the chicks were fed commercial grower ration (approximately 1.0% Ca, .6% available P) and half were fed commercial layer ration (approximately 3.25% Ca, .5% available P). Birds remained on their respective diets until 18 wk of age. Kidney function studies were conducted on anesthetized birds at 6 wk of age prior to initiation of the diet treatments, at 10 wk of age, and at 18 wk of age. The layer ration increased Ca excretion, decreased inorganic phosphate excretion, and decreased urine hydrogen ion concentration in 10-wk-old pullets in comparison with the grower ration. These diet effects on kidney function were attenuated when the pullets reached 18 wk of age. The layer ration also caused an 11.5% incidence of urolithiasis, and significantly increased kidney asymmetry in 18-wk-old pullets relative to the effects of the grower ration. Gray strain IBV exposure significantly increased kidney asymmetry in 18-wk-old pullets, but had no gross effect on kidney function clearly related to the etiology of urolithiasis. Gray strain IBV did not enhance the incidence of urolithiasis in any of the age groups.

Age Factors↗

PubMed1988

Effect of dietary acidification and alkalinization on urolith formation and renal function in Single Comb White Leghorn laying hens.

One of the major causes of mortality in poultry is urolithiasis. Although two of the major causes of urolithiasis have been defined, active and preventative treatments for this disease have not been extensively field tested. Previous research demonstrated that a diet acidified with NH4Cl was effective in preventing the formation of uroliths in 16-wk-old pullets. In the present study, experiments were designed to evaluate the effects of dietary acidification and alkalinization on preformed uroliths in mature laying hens. Urolithiasis was induced by feeding excess dietary Ca (in commercial layer ration) during pullet growout (6 to 18 wk of age) and during the early laying period (18 to 32 wk of age). At 32 wk of age birds were randomly divided into three diet treatment groups: a normal layer ration group, an acidified layer ration group (1% NH4Cl added); and an alkalinized layer ration group (1% NaHCO3 added). Each group received the respective diets until 52 wk of age, when the experiment was terminated. Blood gas analysis at 44 wk of age demonstrated that hens fed the acidified diet had significantly higher blood H+ concentrations, lower blood bicarbonate concentrations, and lower total blood carbon dioxide levels than hens fed the alkalinized layer ration. At 52 wk of age, hens fed the acidified layer ration had higher urinary H+ concentrations, higher blood H+ concentrations, and lower blood HCO3 and total CO2 concentrations than hens fed the normal and alkalinized layer rations. The acidified layer ration group had no uroliths present in their ureters (0% urolithiasis), whereas the normal and alkalinized layer ration groups had 8.3 and 13.1% incidences of urolithiasis.(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonium Chloride↗

PubMed1987

Renal regulation of avian calcium and phosphorus metabolism.

Avian plasma calcium (Ca) and inorganic phosphate (Pi) concentrations are coregulated by parathyroid hormone (PTH) and vitamin D acting directly or indirectly on the intestine, bone and kidneys. Within the overall scheme of chemical, hormonal and target tissue interactions, the kidneys serve as a safety valve, operating on a minute-to-minute basis to excrete Ca and Pi when these minerals are present in excess or to conserve Ca and Pi when they are needed for eggshell formation or bone mineral replenishment. This key role of the kidneys is directly mediated by PTH, acting to stimulate Ca reabsorption and increase Pi excretion at the tubular level. By dissociating Ca from Pi transport, the kidneys serve to maintain appropriate blood Ca:Pi concentration ratios during extremes of dietary challenge or bone mineral mobilization. Direct regulatory roles for vitamin D metabolites and calcitonin on avian urinary Ca and Pi excretion have yet to be firmly established.

Animals↗

PubMed1987

A potent hypotensive factor in chicken left ventricle.

Chicken artria and ventricles both have membrane-bound granules which resemble those containing atriopeptin (ANP) in mammals. However, nothing is known about the contents of the avian granules. A previous study in chickens showed that although extracts of whole chicken heart or synthetic rat ANP both caused profound hypotension, ANP caused both natriuresis and diuresis, while chicken heart extract did not. The present study sought to locate the region(s) of chicken heart containing the hypotensive activity, and to observe the effect on sodium and water excretion and blood pressure in rats. Acid extracts of either atrium, either ventricle, ventricular septum, skeletal muscle, and liver were identically prepared from chickens and rats. Extracts were adjusted to the same protein concentration and injected (0.15 ml/kg) into anesthetized Single Comb White Leghorn roosters. Mean arterial pressure (MAP) and the time for recovery were measured. The most potent extract from chicken hearts was from the left ventricle (-38 +/- 1 mm Hg, 149 +/- 9 sec to recover). All other extracts (including right ventricle) produced only small (10-20 mm Hg), short-lived (20-30 sec) decreases in MAP. In contrast, only rat atrial extracts evoked long-lasting hypotension (greater than 40 mm Hg, recovery time greater than 200 sec). A 30-min infusion of the most potent chicken extract (left ventricle, CLV) into rats produced a small but significant natriuresis and diuresis compared to the vehicle time control (P less than 0.05) and the hypotensive response to bolus injection was about one-third that seen in the chicken. The location of potent spasmolytic activity primarily in chicken left ventricle, the different avian renal responses to chicken heart extract and synthetic rat ANP (5), and the weak diuretic, natriuretic, and hypotensive effects of CLV extract in rats all suggest that the chicken heart substance may be different from mammalian ANP.

Animals↗

PubMed1987

Effect of saline adaptation and renal portal sodium infusion on glomerular size distributions and kidney function in domestic fowl.

Experiments were designed to evaluate acute and chronic effects of sodium on glomerular size distributions and kidney function of Single Comb White Leghorns. Chicks were raised on either tap water (control) or .6% NaCl (saline) drinking water. Kidney function studies were conducted when the birds reached 14 to 16 weeks of age. Saline-adapted birds had significantly lower glomerular filtration rates and significantly higher sodium and potassium excretion rates when compared with birds raised on tap water. Acute effects of sodium on kidney function were assessed by infusing 25 mM tetrasodium pyrophosphate unilaterally into the renal portal system. For birds raised on tap water, unilateral sodium infusion caused a significant unilateral reduction in the glomerular filtration rate. However, neither the acute nor the chronic reductions in glomerular filtration rates in response to sodium were associated with a reduction in the number of filtering nephrons. Saline-adapted birds had significantly hypertrophied glomeruli.

Animals↗

PubMed1987

Effect of dietary acidification on kidney damage induced in immature chickens by excess calcium and infectious bronchitis virus.

Experiments were designed to evaluate the effect of dietary acidification on the development of kidney lesions induced by excess dietary calcium (Ca) and Gray strain infectious bronchitis virus (IBV). Specific pathogen-free (SPF) chicks and SPF chicks inoculated with Gray strain IBV were fed one of three diets: a commercial pullet grower ration (1% Ca); a commercial layer ration (3.25% Ca); or layer ration plus .5% ammonium chloride (acidified layer ration). Gray strain IBV significantly reduced total kidney weights in males, reduced total kidney weight as a percentage of body weight in males, increased the number of gross kidney lesions, and decreased the number of filtering nephrons when compared with uninoculated birds when both groups were fed the grower ration. The layer ration induced a 60% incidence of kidney lesions, caused a significant increase in kidney weight asymmetry ratios, and caused a 25% reduction in the number of filtering nephrons. Acidifying the layer ration significantly reduced the incidence of gross kidney lesions and reduced kidney weight asymmetry ratios, but did not prevent Ca-induced reductions in filtering nephrons.

Acidosis↗

PubMed1987

Avian diuretic response to renal portal infusions of the mycotoxin citrinin.

Citrinin is a nephrotoxic mycotoxin produced by common molds. Previous research has shown that citrinin causes increased urine flow, increased free water clearance, and increased sodium, potassium, and inorganic phosphate excretion. The present study was conducted to evaluate the dose-response effects of citrinin and to further evaluate previously reported phosphaturic effects of citrinin. Ureteral urine was collected from anesthetized domestic fowl during a control period (30 min) and during unilateral renal portal infusion (90 min) of citrinin carrier vehicle, 200 ppm citrinin, or 400 ppm citrinin. Comparisons of the portal infused vs. uninfused kidneys were used to evaluate the direct effects of citrinin. Citrinin caused acute (unilateral) dose-related increases in urine flow, free water clearance, and fractional sodium excretion and dose-related decreases in urine osmolality. Citrinin had no direct effect on glomerular filtration rates, fractional potassium excretion, or fractional inorganic phosphate excretion. An additional group of birds received systemic intravenous infusions of parathyroid hormone (PTH) beginning 40 min after the start of unilateral renal portal infusion of citrinin. The citrinin and PTH infusion were continued for 60 min. Fractional inorganic phosphate excretion increased bilaterally during the citrinin-PTH infusion period but citrinin had no direct phosphaturic effect. Previously reported phosphaturic effects of citrinin were not confirmed in the present study.

Animals↗

PubMed1987

Evaluation of sex differences in embryonic heart rates.

Adult female chickens are known to have higher heart rates than adult males. Previous evidence suggested that sex-related differences in heart rates exist in embryos. The objective of the present study was to determine if differences in heart rate can be used for sexing chickens during embryonic development. The effects of hyper and hypothermia also were evaluated. On Day 14 of incubation, Single Comb White Leghorn embryos were candled and three surface electrodes were placed on the eggshell. The electrodes were attached to an electrocardiograph. Heart rates were recorded from Days 15 to 20 of incubation. Female embryos exhibited higher mean heart rates than males (2 to 4 beats/min) for Days 15 to 19 of incubation. Average heart rates of male and female embryos decreased and were significantly different when exposed to hypothermia (26.1 C for 2 h) on Day 15 of incubation. Hyperthermia (39.4 C for 45 min) on Day 15 of incubation increased embryonic heart rates, but male and female heart rates did not differ significantly. Extensive overlap between male and female heart rates under normal and hypothermic conditions makes this technique an industrially impractical method for determining embryonic sex.

Animals↗

PubMed1986

Effects of atriopeptin and chicken heart extract in Gallus domesticus.

Effects of Ser-Leu-Arg-Arg-atriopeptin III (ANP) and chicken heart extract (CHE) were compared during unilateral renal portal infusion in anesthetized Single Comb White Leghorn chickens. The purpose was to determine whether renal effects were glomerular and/or tubular. Both CHE and ANP caused substantial decreases in mean arterial pressure but had different renal actions. ANP caused small but significant increases in both absolute and fractional sodium excretion, but these effects were modest compared with those reported in mammals. Although there was a tendency for higher fractional sodium excretion in the portal infused kidney, the difference was not significant (0.1 less than P greater than 0.05). ANP also increased glomerular filtration rate (GFR), urine flow rate (UFR), and osmolal clearance and decreased estimated renal vascular resistance. In contrast, CHE decreased GFR and increased resistance. In contrast, CHE decreased GFR and increased fractional potassium excretion in the infused kidney. After CHE infusion was stopped, GFR and UFR increased, and there was a further transient kaliuresis. No natriuretic effects were ever seen with CHE. Chickens apparently lack potent mammalian-type cardiac natriuretic factor(s) and/or have a limited capacity for natriuresis in response to mammalian ANP. Because hypotension was the most prominent avian response to both CHE and ANP, endogenous vasoactive factor(s) in chicken hearts may function to regulate blood pressure rather than blood volume.

Animals↗

PubMed1986

Characterization and composition of uroliths from domestic fowl.

Urolithiasis (kidney stone formation) is an acquired degenerative kidney lesion affecting sexually mature and immature domestic fowl. For the present study, uroliths were collected from three commercial flocks during outbreaks of urolithiasis. Uroliths also were collected from a research flock in which urolithiasis was induced by feeding immature chickens a diet formulated to contain excess calcium (3.25% Ca) and .4% available phosphorus. All uroliths were tested by x-ray diffractometry, infrared spectrophotometry, and emission spectrography. With one exception, the stones were composed of compact masses of microcrystalline to fine pleomorphic crystals of calcium sodium urate, with random substitution of magnesium for calcium, and potassium for sodium. No initiating nidus was evident. One of four stones from one laying hen flock was positively identified as an ammonium acid (hydrogen) urate. The unique calcium-sodium-urate stone composition in all but one of the stones tested suggests that similar processes were involved in stone formation in the four different flocks.

Animals↗

PubMed1986

Kidney function in domestic fowl with chronic occlusion of the ureter and caudal renal vein.

A previously published technique for producing renal insufficiency in chicks involves ligating the caudal renal vein together with the ureter near the midpoint of the kidney. This ligation occludes the normal route (caudal renal vein) by which blood exits the medial and posterior kidney divisions. The present study was conducted to evaluate kidney function following chronic caudal renal vein and ureter occlusion. The ureters and caudal renal veins of 2 to 3-week-old chicks were clamped with hemostatic clips (Clamp Group), and kidney function evaluations were conducted when the birds reached 14 weeks of age. Plasma values [osmolality, Na, K, Ca, inorganic P (Pi)] of control, sham, and clamp groups did not differ significantly. Plasma uric acid concentrations did not differ when the control and clamp groups were compared. Clamping the ureter near the midpoint of the kidney caused a significant reduction in the number of filtering glomeruli per kidney, but due to compensatory hypertrophy the kidney weights of the groups did not differ significantly. Kidney function comparisons (urine flow rates, glomerular filtration rates, renal plasma flow rates, urine pH, fractional excretion of Na, K, Ca, Pi, and uric acid) revealed a significant reduction in Na and K excretion by the clamp group, but other renal function parameters did not differ significantly. These experiments demonstrate that chickens have a remarkable capacity to survive significant reductions in renal mass and to adapt to major disruptions of blood flow patterns.

Animals↗

PubMed1985

Comparisons of avian renal responses to bovine parathyroid extract, synthetic bovine (1-34) parathyroid hormone, and synthetic human (1-34) parathyroid hormone.

The structure of avian parathyroid hormone (PTH) is only partially known, therefore studies of the avian renal responses to PTH have been conducted using bovine parathyroid extract (bPTE), synthetic human PTH (h(1-34)PTH), and synthetic bovine PTH (b(1-34)PTH). In vitro studies indicate that these peptides may have quite different chick kidney receptor binding affinities and adenylate cyclase activation potencies. In the present study, the in vivo renal responses to bPTE, b(1-34)PTH, and h(1-34)PTH have been compared in immature domestic fowl. The following parameters were evaluated: glomerular filtration rates; renal plasma flow rates; urine pH; and fractional excretion of sodium, potassium, chloride, calcium, magnesium, and inorganic phosphate. Overall, the different hormonal peptides elicited qualitatively similar responses: they all were phosphaturic, natriuretic, diuretic, hypomagnesiuric, hypocalciuric, and kaliuretic. This is the first study to show an effect of PTH on renal magnesium transport in avian species. Quantitative comparisons make it clear that bPTE is more natriuretic and diuretic, but less phosphaturic than either b(1-34)PTH or h(1-34)PTH. A temporal dissociation of the phosphaturic response from the other mineral and electrolyte responses suggests that the phosphaturic response is mediated by a separate mechanism.

Animals↗

PubMed1985

Avian renal responses to oxidized and nonoxidized bPTH(1-34).

The hypotensive, hypercalcemic, and hyperphosphaturic responses to bovine synthetic 1-34 amino acid parathyroid hormone [bPTH(1-34)] were simultaneously evaluated in anesthetized laying hens, and compared to the same responses to oxidized (0.3% hydrogen peroxide) bPTH(1-34) prepared from the same commercial batch of hormone. The oxidized and nonoxidized hormones were administered intravenously into separate groups of animals, which were also receiving a constant intravenous infusion of inulin and p-aminohippuric acid (PAH) to serve as renal clearance test markers. bPTH(1-34) caused a 33.25 +/- 7.05 mm Hg decrease in mean arterial blood pressure. The corresponding change in response to the oxidized hormone preparation was a 10.75 +/- 1.49 mm Hg decrease, a significant reduction in hypotensive activity compared to the intact hormone. In contrast, oxidation had no influence on the hypercalcemic or hyperphosphaturic (relative clearance of phosphate, CPO4/CIn) responses to bPTH(1-34), both preparations causing significant and parallel increases in these variables. Both hormone preparations also caused increases in urine flow rate, GFR, CPAH, CCa/CIn, CK/CIn, CNa/CIn, and urine pH. However, on the basis of percentage change from the respective control periods, only CNa/CIn and urine pH showed significant differences between the two hormone preparations, with the intact hormone causing greater natriuresis and urine alkalinization than the oxidized hormone. The failure of peroxide oxidation to significantly affect the renal hyperphosphaturic response to bPTH(1-34) in chickens contrasts with results reported on mammalian species, and may be related to differences in the mechanism of renal phosphate transport between these groups.

Animals↗

PubMed1985

Parathyroid transplants and unilateral renal delivery of parathyroid hormone in domestic fowl.

Exogenous parathyroid hormone (bovine 1-84 PTH) was infused unilaterally into the renal portal system or unilaterally into the renal arterial system of domestic fowl. Endogenous PTH was secreted unilaterally into the renal portal system by parathyroid tissue transplanted to the leg muscle. None of the experimental protocols caused significant unilateral phosphaturia, although unilaterally infused kidneys were shown to have received significantly more PTH than the contralateral kidneys. The transplanted parathyroid tissue was a major source of endogenous PTH, as was indicated by the development of significant hypocalcemia following surgical removal of the transplant. Unilateral PTH infusion did cause a significant unilateral increase in sodium excretion and significant bilateral phosphaturia. These results demonstrate that the phosphaturic and natriuretic responses to PTH can be dissociated in clearance experiments.

Animals↗

PubMed1985

Arterial blood gas, pH, and bicarbonate values in laying hens selected for thick or thin eggshell production.

Bicarbonate, pH, carbon dioxide partial pressure (pCO2), and oxygen partial pressure (pO2) were measured in blood samples collected anaerobically from the brachial arteries of domestic fowl from lines selected for thick (TK) or thin (TN) eggshell production. The blood values of TK and TN hens were compared 6 hr prior to oviposition and continued at 2-hr intervals until 10 hrs postoviposition. Percent shell values were measured for eggs laid 2 days prior to and during blood sampling. Hens with TK shells had significantly (P less than .001) higher percent shell values than hens with TN shells. The measured blood parameters (bicarbonate, pH, pCO2, and pO2) did not differ significantly (P greater than .05) when TK and TN hens were compared at the time of oviposition. However, between 2 and 6 hr postoviposition, TN hens had significantly lower blood pH, pO2, and bicarbonate than did TK hens. Arterial pCO2 tended to be higher in TN hens than in TK hens, but this difference was significant only at 6 hr preoviposition. These results show that TN hens develop metabolic acidosis relative to TK hens during the first 6 hr postoviposition.

Acidosis↗

PubMed1985

A comparison of two techniques for determining glomerular size distributions in domestic fowl.

Nephrons in the avian kidney have an extremely heterogeneous size distribution. The shortest nephrons have very small glomeruli, and the larger nephrons have very large glomeruli. Physiological, nutritional, and disease factors may be correlated with the functioning of different sized nephrons. The present study was conducted to compare two techniques for measuring glomerular size distributions. A postmortem India ink infusion technique gave results that were highly comparable to an in vivo alcian blue infusion technique. Single Comb White Leghorn pullets were found to have approximately 270,000 glomeruli per kidney; glomerular circumferences and diameters ranged between .07 to .42 mm and .02 to.14 mm, respectively. A unimodal size distribution was found, with most glomeruli falling within the circumference range of .15 to .26 mm. The alcian blue technique should provide a quantitative in vivo method for evaluating selective tubular damage or physiological glomerular intermittency.

Alcian Blue↗

PubMed1985

Induction of urolithiasis in single comb white Leghorn pullets: effect on glomerular number.

Urolithiasis was induced in an experimental group of Single Comb White Leghorn pullets by feeding them layer ration and exposing them to nephrotrophic Gray strain infectious bronchitis virus (IBV). Gray strain IBV was recovered from kidney and cloacal swabs for up to 26 days after exposure to the virus. Control pullets fed pullet grower ration and not exposed to Gray strain IBV did not develop urolithiasis. The experimental design did not allow differentiation between the roles of layer ration and IBV in triggering urolithiasis. Urolithiasis was associated with asymmetry in left vs. right kidney weight comparisons for individual pullets. Pullets from the urolithiasis group had 43,800 +/- 4,500 glomeruli/gram kidney weight, whereas control pullets had 68,770 +/- 3,500 glomeruli/gram kidney weight. This difference was significant (P less than .01). Total kidney weights did not differ significantly when the experimental and control pullets were compared. Comparisons of glomeruli size distributions indicated that the number of intermediate sized glomeruli (.15 to .22 mm in circumference) was significantly reduced in pullets from the urolithiasis treatment group. These observations indicate that a significant reduction in nephron number can be masked by compensatory hypertrophy of the remaining kidney tissue in pullets with urolithiasis.

Animals↗

PubMed1985

Kidney function of single comb white Leghorn pullets following acute renal portal infusion of the mycotoxin citrinin.

Poultry consuming diets contaminated with citrinin excrete copious quantities of urine and exhibit increased water consumption. The present study was conducted to determine if citrinin acts directly on the kidneys and, if so, to provide a detailed physiological evaluation of the nephrotoxic effects of citrinin. Single Comb White Leghorn pullets were anesthetized and prepared for renal function studies. Ureteral urine was collected during a pre-infusion period (30 min), during unilateral renal portal infusion of 200 ppm citrinin (30 min), and during a recovery period following citrinin infusion (90 min). Pilot studies had shown that 200 ppm citrinin is the lowest dose capable of causing consistent unilateral responses when infused at a rate of .2 ml/kg body weight (BW) X min. The responses of the portal-infused kidneys were compared with the responses of the contralateral (uninfused) kidneys to determine the direct effects of citrinin. Citrinin had no acute direct (unilateral) effect on glomerular filtration rate, renal plasma flow rate, urine pH, or fractional calcium or magnesium excretion. Citrinin caused rapid unilateral increases in urine flow rates, free water clearance, and in fractional sodium, potassium, and inorganic phosphate excretion. Increased solute excretion did not compensate for increased free water clearance, as reflected by a significant decrease in urine osmolality. Recovery from the effects of citrinin occurred within 30 min after cessation of unilateral renal portal infusion. No histopathological damage was seen when citrinin was infused at 200 and 800 ppm, although dose-related increases in urine flow and decreases in urine osmolality were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗