Plasma Phosphorus Levels Research Articles

Effect of exercise on occurrence of diurnal rhythms of plasma ions and metabolites in Thoroughbred racehorses

Records of plasma calcium (Ca++), phosphorus (Pi), potassium (K+), sodium (Na+), chloride (Cl-), magnesium (Mg++), iron (Fe++), glucose, cholesterol, triglycerides and total protein levels were measured to determine the effects of exercise on occurrence of diurnal rhythms in Throughbred racehorses (n=7) under physical training. Physical activities consisted of gallop on the track and walking. Blood samples were collected from jugular vein every 4h over a 48h period. Plasma Ca++, K+, Mg++ and Na+ levels were obtained by flame photometry; and, Pi, Cl-, Fe++, glucose, cholesterol, triglycerides and total protein levels were measured by colorimetric tests using visible UV spectrophotometry. The data were analyzed using a 24h period to each exercise performed. Diurnal rhythm of Pi was observed when walking was the physical activity performed, and its acrophase occurred at the light period. Plasma triclycerides showed significant diurnal rhythms, with their acrophases occurring at the dark period, even when walking or gallop were performed. High intensity exercise (gallop) decreased triglycerides amplitude. No significant diurnal rhythms of other variables were found. Gallop, as physical activity, masked phosphorus diurnal rhythm. However, physical training did not influence triglycerides diurnal rhythm occurrence. High intensity exercise (gallop) just declined triglycerides amplitude.

Effects of feeding raw or reconstituted high tannin red sorghum on nutrient utilisation and certain welfare parameters of broiler chickens

1. A feeding trial was conducted on 360 1-d-old chicks from 0 to 6 weeks of age to assess the effect of processed high tannin red sorghum in the diet of broiler chickens on nutrient utilisation and certain welfare parameters. 2. Each of 9 dietary treatments was allotted to 4 groups (replicates) of chicks in a completely randomised design. The treatments were a maize–soy based standard broiler diet (control, RS0) and eight test diets formulated by incorporating either raw red sorghum (RS25, RS50, RS75, RS100) or reconstituted red sorghum () replacing 25, 50, 75 or 100% of maize from the control diet. 3. The tannin content was reduced from 23 to 16 g/kg in reconstituted red sorghum. 4. Utilisations of nitrogen, calcium and phosphorus retention were similar in all the dietary groups. 5. The cell-mediated immune response measured as footpad index (FPI) value of birds given raw red sorghum was significantly higher than in control and reconstituted red sorghum groups. Similarly, comparatively better humoral response measured as HA titre value was observed in raw red sorghum based groups than in reconstituted ones. 6. Plasma albumin, globulin, protein, glucose, calcium, phosphorus, SGOT, SGPT and uric acid levels did not differ significantly due to dietary treatments. 7. Mild histopathological changes were observed in liver and kidney tissues of birds given raw red sorghum. 8. From the present study, it is concluded that (1) the reconstitution of high tannin red sorghum resulted in about 30% reduction in its tannin concentration; (2) the feeding of reconstituted sorghum based diets to broiler chickens did not exert any appreciable influence on nutrient utilisation, blood biochemicals and enzymes and gross pathological changes; and (3) the birds fed on raw red sorghum exhibited higher immuno-responsiveness in comparison to their reconstituted counterparts.

FGF-23 and sFRP-4 in Chronic Kidney Disease and Post-Renal Transplantation

Background: The phosphatonins fibroblast growth factor-23 (FGF-23) and FRP-4 are inhibitors of tubular phosphate reabsorption that may play a role in the hyperphosphatemia associated with chronic kidney disease (CKD) or in the hypophosphatemia associated with renal transplants. Methods: Plasma FGF-23, FRP-4, phosphorus and parathyroid hormone were measured in patients at all stages of CKD. Phosphate regulation of FGF-23 and secreted frizzled related protein-4 (sFRP-4) was examined in end-stage renal disease patients in the presence and absence of therapeutic phosphate binder usage. In renal transplant patients, plasma FGF-23, sFRP-4 and phosphorus concentrations were determined before and 4–5 days after transplantation. Results: Plasma FGF-23 correlated with creatinine clearance (r² = –0.584, p < 0.0001) and plasma phosphorus (r² = 0.347, p < 0.001) in CKD patients and with plasma phosphorus (r² = 0.448, p < 0.001) in end-stage renal disease patients. Phosphate binder withdrawal increased FGF-23 levels. In kidney transplant patients, dramatic decreases in FGF-23 (–88.8 ± 5.4%) and phosphorus (–64 ± 10.2%) were observed by 4–5 days post-transplantation. In patients with post-transplant hypophosphatemia, FGF-23 levels correlated inversely with plasma phosphorus (r² = 0.661, p < 0.05). sFRP-4 levels did not change with creatinine clearance or hyperphosphatemia in CKD or end-stage renal disease patients, and no relation was noted between post-transplant sFRP-4 levels and hypophosphatemia. Conclusions: In CKD, FGF-23 levels rose with decreasing creatinine clearance rates and increasing plasma phosphorus levels, and rapidly decreased post-transplantation suggesting FGF-23 is cleared by the kidney. Residual FGF-23 may contribute to the hypophosphatemia in post-transplant patients.

The Kidney Disease Outcomes Quality Initiative (K/DOQI) Guideline for Bone Metabolism and Disease in CKD: Association With Mortality in Dialysis Patients

In 2003, the National Kidney Foundation-Kidney Disease Outcomes Quality Initiative (K/DOQI) published a guideline recommending tight control of serum calcium, phosphorus, calcium-phosphorus product (Ca x P), and intact parathyroid hormone levels in patients with chronic kidney disease. Within the context of this guideline, we explored associations of these plasma concentrations with all-cause mortality risk in incident dialysis patients in The Netherlands. In a large, prospective, multicenter, cohort study (Netherlands Cooperative Study on the Adequacy of Dialysis), we included 1,629 patients new on hemodialysis or peritoneal dialysis therapy between 1997 and 2004. Multivariate Cox regression models containing calcium level, phosphorus level, intact parathyroid hormone level, age, comorbidity, primary kidney disease, nutritional status, albumin level, dialysis dose, and hemoglobin level were used to examine mortality risks. Mean age was 60 +/- 15 (SD) years, 61% were men, and 64% were treated with hemodialysis. In adjusted time-dependent survival analysis, all-cause mortality risk increased in hemodialysis patients by 40% (hazard ratio [HR], 1.4; 95% confidence interval [CI], 1.1 to 1.7) and in peritoneal dialysis patients by 60% (HR, 1.6; 95% CI, 1.1 to 2.4) for plasma phosphorus levels greater than the target. In addition, having elevated plasma Ca x P product levels increased mortality risk by 40% (HR, 1.4; 95% CI, 1.1 to 1.8) in hemodialysis patients and 50% in peritoneal dialysis patients (HR, 1.5; 95% CI, 1.0 to 2.2). In both patient groups, no significant effects were observed for plasma levels less than the targets. In time-dependent survival analysis, the presence of plasma phosphorus and Ca x P product concentrations greater than K/DOQI targets increased all-cause mortality risk in hemodialysis and peritoneal dialysis patients.

Which vitamin D derivative to prescribe for renal patients

It is possible to control the secondary hyperparathyroidism and osteitis fibrosa of patients with chronic kidney disease by calcitriol when given early and in appropriate doses. However, this control is often achieved at the price of unacceptably high plasma calcium and phosphorus levels, the induction of adynamic bone disease, and soft tissue calcification. To avoid these side effects, so-called 'nonhypercalcemic' vitamin D analogs have been developed. Their possible advantages and their precise place in the treatment and prevention of secondary hyperparathyroidism remain a matter of debate. A large US multicenter study showed that the administration of the vitamin D analog paricalcitol to hemodialysis patients, as compared with calcitriol, was associated with better survival. In a subsequent large US multicenter study paricalcitol-treated hemodialysis patients experienced fewer hospitalizations and hospital days compared with calcitriol-treated patients. In a third, smaller study from Japan, regular alfacalcidol users among hemodialysis patients had better cardiovascular survival than nonusers. Finally, in a recent historical control study the mortality of a large hemodialysis patient cohort was analyzed as a function of previous vitamin D treatment. Patients on active vitamin D compounds at any time had a 2-year survival advantage over vitamin D-naive patients. It must be pointed out, however, that all four studies were retrospective in nature. The development of vitamin D analogs with less side effects than with calcitriol is of major theoretical interest. Practically speaking, however, we still need to be convinced that this goal can be achieved in chronic kidney disease patients.

Differences between metabolic profiles of egg-type and meat-type hybrid hens

The main objective of this study was to compare the metabolic profile (i.e. selected haematological and biochemical parameters in blood plasma) of production egg-type hybrid hens (E, MORAVIA BSL) with that of meat-type hybrid hens (M, COBB 500), and to evaluate dynamic changes occurring during the laying period from the 25th to 50th week of age. The study was prompted by both poultry farmers and veterinary practitioners since parameters defining the health of layers are absent. Selected parameters of the metabolic profile of layers were monitored regularly in 5-week intervals during egg laying. Samples of blood for haematological and biochemical examination were obtained by puncture of the vena basilica and stabilized by heparin. The study has revealed that monitored parameters of the metabolic profile significantly vary with factors such as production type, nutrition, and egg-laying intensity. Enhanced metabolism in egg-type hens was reflected in erythropoiesis which increased (in comparison with meat-type hens) highly significantly (P &amp;le; 0.01), particularly for erythrocyte count 2.36 T/l (2.14&amp;nbsp;T/l), haematocrit level 0.32 l/l (0.30 l/l), content of haemoglobin 94.48 g/l (84.18 g/l) and leukocyte count 17.06&amp;nbsp;G/l (13.22&amp;nbsp;G/l). Similarly, enhanced metabolism in egg-type hens also led to a highly significant increase (P &amp;le; 0.01) in the levels of biochemical parameters in blood plasma, particularly the total level of protein was 57.62 g/l (50.98) g/l), glucose 14.03 mmol/l (13.36 mmol/l), cholesterol 5.34 mmol/l (3.73 mmol/l) and calcium 6.52 mmol/l (5.52 mmol/l). ) In the case of the plasma level of phosphorus, no significant difference was found between egg-type hens (1.58 mmol/l) and meat-type hens (1.59 mmol/l). The reported results are based on the total of 180 haematological and biochemical analyses performed during the laying period. The results are crucial not only for future development of avian haematology and biochemistry, but also in respect to veterinary practice. &amp;nbsp; &amp;nbsp;

Clinical experience with cinacalcet HCl.

Secondary hyperparathyroidism (SHPT) is associated with parathyroid gland hyperplasia, increased parathyroid hormone (PTH) production and secretion, disturbed bone and mineral metabolism, soft tissue calcification and an increased risk of death. The condition is an almost universal complication of end-stage renal disease (ESRD) and currently is managed by treatment with phosphate binders and vitamin D compounds, both of which are associated with significant side effects, including hypercalcaemia and hyperphosphataemia. Therapy with calcimimetics is a new approach to the treatment of SHPT. These agents act at the calcium-sensing receptor (CaR), where they increase the sensitivity of the receptor to ionized serum calcium. Activation of the CaR results in a rapid reduction in PTH secretion. The calcimimetic drug cinacalcet HCl currently is undergoing clinical trials in dialysis patients who have uncontrolled SHPT, despite treatment with vitamin D compounds and/or phosphate binders. Clinical trials have confirmed that the drug rapidly reduces plasma PTH, phosphorus and calcium-phosphorus product (Ca x P) levels, and that levels of PTH, phosphorus and Ca x P remain suppressed for up to 3 years. In clinical trials, cinacalcet HCl was a well-tolerated drug; only nausea and vomiting occurred more frequently in patients who took cinacalcet HCl than in those who took placebo, and the occurrence of transient hypocalcaemia was limited to the initial phase of the treatment. Cinacalcet HCl is therefore a potentially highly effective and well-tolerated treatment for SHPT in patients with ESRD.

Plasma magnesium in adult asthmatics at the Lagos University Teaching Hospital, Nigeria.

To determine the plasma magnesium levels in adult asthmatics. Case control study. Lagos University Teaching Hospital, Lagos, Nigeria. Forty stable asthmatics and thirty five apparently healthy controls. Detailed history including drug history was obtained from patients and controls. Fasting venous blood was collected into heparinized tubes from both patients and controls. Plasma magnesium, albumin, calcium and phosphorus were measured using spectrophotometric end point methods. Mean (SD) plasma magnesium concentration of 0.93(0.24) mmol/L in the asthmatics was significantly lower compared to the controls which was 1.15(0.28) mmol/L, p<0.001. There was no significant difference in the plasma albumin, calcium and phosphorus levels between the patients and controls. Plasma magnesium levels correlated with the plasma albumin level (r=0.62) but did not correlate with the duration of disease, peak flow rate and age of patients. There was no gender difference in plasma magnesium levels in the asthmatics. Adult Nigerian asthmatics have lower plasma magnesium concentrations compared to healthy controls. This may be of use in future therapeutic management of asthma. A large scale multi-centre study needs to be carried out since this study was done in one hospital.

Calcimimetics versus Vitamin D: What Are Their Relative Roles?

A strict control of secondary hyperparathyroidism in patients with chronic kidney disease (CKD) is indicated to avoid serious complications linked to osteitis fibrosa and other parathyroid-hormone (PTH)-related bodily disturbances. However, such a control is often achieved only at the price of unacceptably high plasma calcium and phosphorus levels and the risk of soft tissue calcification, even when using the novel, so-called ‘non-hypercalcemic’ vitamin D analogs. The advent of a new class of drugs, the calcimimetics, should allow a more adequate control of the disturbed calcium-phosphorus metabolism in CKD patients. In my opinion, the calcimimetics will not replace currently used medications but will be a valuable supplement to presently available treatment options for this major complication in patients with renal failure.

Diurnal Rhythms of Plasma Ions and Metabolites Levels in Thoroughbred Racehorses

The purposes of this study were to observe the presence of diurnal rhythms in plasma ions and metabolites levels in Thoroughbred racehorses under physical training, and to determine the time of blood sampling in clinical investigations. Plasma calcium, phosphorus, potassium, sodium, chloride, magnesium, iron, glucose, cholesterol, triglycerides, and total proteins levels were studied over a 72-h period. Blood samples were taken every 4 hours from five male and five female Thoroughbred racehorses under physical training. COSINOR analyses (P = 0.05) were done. Plasma potassium and triglycerides showed significant diurnal rhythms, with its acrophases occurring at dark period. No significant diurnal rhythms of other variables were found. It was concluded that, in Thoroughbred racehorses, the optimum time for potassium, and triglycerides sampling seems to be light period. And for other variables, time of diagnosis is not important.

Urea percentiles in children with chronic renal failure. Data from the ItalKid project.

In chronic renal failure high serum urea levels (sUrea) are correlated with the onset of uremic symptoms. Urea has generally been considered relatively non-toxic, functioning more as a surrogate for other toxic solutes; however, it has been recently reported that it can contribute to uremic toxicity. Clinically sUrea are often difficult to interpret because of the wide range of kidney functions. To obtain a practical and easily accessible tool to evaluate sUrea, we have produced percentile curves for different ranges of chronic renal failure, defined with creatinine clearance ( C(Cr)) obtained with the Schwartz formula. Data were obtained from the Italian Pediatric Registry of Chronic Renal Failure (ItalKid); its inclusion criteria are: (1) C(Cr )<75 ml/min per 1.73 m(2), (2) age <20 years at time of registration, and (3) conservative treatment. To obtain the percentiles, the following patients were excluded: patients with an underlying disease, a concomitant treatment, or a disorder that could affect urea metabolism, per se, and/or food intake, and patients aged <2 years. The study group included 690 subjects (mean age 9.56+/-4.54 years, 485 males). In total, 2,085 observations (C(Cr )and sUrea) were available for the construction of the percentile curves. A median of 258 (range 99-380) observations was obtained for each of the eight different categories of C(Cr )(intervals of 10 ml/min per 1.73 m(2)). The 10th, 25th, 50th, 75th, and 90th percentiles were calculated and a graph was produced. Patients with the highest urea percentiles showed significantly higher plasma levels of phosphorus and parathyroid hormone and significantly lower hemoglobin concentrations and bicarbonate levels. Our percentile curves may help to identify subjects with inappropriate sUrea for a given C(Cr).

Plasma phosphorus content and dietary phosphorus availability in adult sheep

This study was aimed at discriminating different quality phosphorus sources using plasma phosphorus kinetics in sheep. Four adult castrated Vendean sheep received successively two preliminary usual then low phosphorus diets (three weeks on 2.5 g P·kg -1 DM and three weeks on 1.5 g P·kg -1 DM), and then one of four compared diets (2.5 g P·kg -1 DM) in a Youden square design. The four compared diets included either dicalcium phosphate, calcium aluminium phosphate, stan- dard rapeseed meal or formaldehyde-treated rapeseed meal as the main phosphorus source. Inorganic plasma phosphorus was determined in samples taken from the jugular vein from the last week of the first preliminary phase to the last week of the test phase. The first preliminary diet stabilised the plasma phosphorus content (51.2 mg·L -1 , no day effect; no animal effect). The low phosphorus diet induced an initial rapid decrease in plasma phosphorus. After four days, plasma phosphorus in- creased probably resulting from an adjustment in phosphorus homeostasis. During the test phase, dicalcium phosphate and both rapeseed meals were more efficient than calcium aluminium phos- phate in restoring the initial plasma phosphorus levels. Both, rapeseed meal diets induced the highest plasma phosphorus concentration. The physiological significance of these results is discussed. availability / phosphorus / plasma / sheep

Persistent downregulation of calcium-sensing receptor mRNA in rat parathyroids when severe secondary hyperparathyroidism is reversed by an isogenic kidney transplantation.

Experimental severe secondary hyperparathyroidism (HPT) is reversed within 1 wk after reversal of uremia by an isogenic kidney transplantation (KT) in the uremic rats. Abnormal parathyroid hormone (PTH) secretion in uremia is related to downregulation of CaR and vitamin D receptor (VDR) in the parathyroid glands (PG). The aim of this investigation was to examine the expression of CaR and VDR genes after reversal of uremia and HPT in KT rats. 5/6 nephrectomized rats were kept on a normal or high-phosphorus (hP) diet for 8 wk to induce severe HPT (n = 8 in each group). In another group of seven uremic hP rats, uremia was reversed by an isogenic KT and PG were harvested within 1 wk posttransplant. Plasma urea, creatinine, total calcium, phosphorus, and PTH levels were measured. Parathyroid CaR and VDR mRNA were measured by quantitative PCR. Uremic hP rats had significantly elevated levels of creatinine, urea, and phosphorus (P < 0.001) and developed significant hypocalcemia (plasma calcium 1.83 +/- 0.2 mmol/L; P < 0.001) compared with normal control rats. After KT, the levels were normalized from day 3 to 7: creatinine from 0.117 +/- 0.016 to 0.050 +/- 0.002 mmol/L; urea from 23 +/- 4 to 7 +/- 0.3 mmol/L; phosphorus from 3.9 +/- 0.6 to 1.5 +/- 0.06 mmol/L; calcium from 1.8 +/- 0.2 to 2.5 +/- 0.02 mmol/L. Plasma PTH levels fell from 849 +/- 224 to a normal level of 38 +/- 9 pg/ml (P < 0.01). In uremic rats on a standard diet, CaR mRNA was similar to that of normal control rats, whereas VDR mRNA was significantly decreased. In uremic rats kept on hP diet, CaR mRNA was significantly decreased to 26 +/- 7% of control rats (P = 0.01) and VDR mRNA reduced to 36 +/- 11% (P < 0.01). In KT, previously hP uremic rats, both CaR mRNA and VDR mRNA remained severely reduced (CaR, 39 +/- 7%; VDR, 9 +/- 3%; P < 0.01) compared with normal rats. In conclusion, circulating plasma PTH levels normalized rapidly after KT, despite persisting downregulation of CaR and VDR gene expression. This indicates that upregulation of CaR mRNA and VDR mRNA is not necessary to induce the rapid normalization of PTH secretion from hyperplastic parathyroid glands.

Impaired Parathyroid Hormone Action on Urinary Phosphorus Excretion in Isolated Perfused Kidney of Streptozotocin-Induced Diabetic Rats

To study the effects of diabetes on the renal actions of parathyroid hormone (PTH), we observed urinary excretion of cyclic adenosine monophosphate (cAMP) and phosphorus in isolated perfused rat kidney. Diabetic rats were kept for 7 days after an intraperitoneal injection of 70 mg/kg streptozotocin (STZ). STZ-induced diabetic rats were treated with a daily injection of 20 U/kg lente-type insulin for 7 days. Plasma albumin, calcium, phosphorus, and PTH levels were not different among normal control, diabetic and insulin-treated diabetic groups. In the control rat kidney, the addition of PTH increased urinary cAMP excretion from 8 +/- 3 to 190 +/- 49 pmol/5 min and urinary phosphorus excretion from 11.3 +/- 4.4 to 33.6 +/- 10.8 microg/5 min. In the STZ-diabetic rat kidney, basal urinary cAMP was impaired, and PTH altered neither urinary cAMP nor phosphorus excretion (from below 0.7 to below 0.7 pmol/5 min, and from 15.5 +/-4.5 to 13.6 +/- 8.1 microg/5 min, respectively). Insulin treatment completely recovered the PTH actions. These results show that insulinopenic diabetes induces PTH resistance in the kidney.

Evaluation of the secondary stress response in healthy Nile tilapia (Oreochromis niloticus L.) after treatment with a mixture of formalin, malachite green and methylene blue

To determine the effects of exposure to a mixture of formalin, malachite green and methylene blue (FMC) on the secondary stress indices, changes in glucose, phosphorus, calcium, magnesium, sodium, potassium and haematocrit were monitored in healthy Nile tilapia, Oreochromis niloticus L. Fish were exposed separately to varying concentrations of a mixture of formalin, malachite green and methylene blue (0.1, 0.5 and 1 p.p.m.) for 1, 10 and 60 min. In general, treatment of fish with FMC elicited marked elevations of plasma glucose. Plasma phosphorus levels dropped after FMC treatment. In fish exposed to FMC, calcium levels in general were lower than those of the controls. Magnesium levels were not influenced by FMC treatment. Plasma sodium and potassium levels showed an unclear pattern for differing FMC concentrations and exposure times. Haematocrit values were affected by FMC treatment.

Retardo de desenvolvimento associado à Osteopetrose

A osteopetrose é uma doença genética rara, com variação na sua expressividade e no seu modo de herança e que caracteriza-se, básicamente, pela esclerose óssea generalizada resultado de um desequilibrio entre formação e reabsorçâo ósseas. Descreveremos um caso desta doença em que um retardo de desenvolvimento associado a fraturas ósseas iniciaram a investigação. E.D.C., 19 anos e 9 meses, foi encaminhado ao serviço médico por alteração esquelética e baixa estatura. Iniciou aumento de volume testicular e pilificaçâo pubiana aos 18 anos, com progressão lenta da puberdade. Há 6 meses apresentou fratura de antebraço após queda da própria altura. Ao exame físico apresentava estatura de 141,5 cm; peso 38,5 kg; estadiamento puberal em GIII PII com idade óssea de 13 anos e 6 meses. O exame radiológico do esqueleto apresentou uma hiperdensidade óssea com alterações típicas de osteopetrose , com sinais de fratura em ulna e colo de fémur, ambos à direita. A densitometria óssea encontrava-se 10,65 e 15,55 desvios-padrão acima da média para sua idade em coluna lombar e fêmur respectivamente. As dosagens hormonais revelaram níveis reduzidos de testosterona total para a idade cronológica (245 ng/dl) com gonadotrofinas basais normais; hormônio de crescimento (GH) responsivo à hipoglicemia e níveis de fator de crescimento semelhante a insulina-l (IGF-I) diminuídos para o estádio puberal. Os níveis de cálcio (Ca), fósforo (P), atividade de fosfatase alcalina (FA) e paratormônio intacto (PTH) plasmáticos estavam dentro da normalidade. A incidência de osteopetrose em nosso meio é bastante rara, e sua associação com baixa estatura e retardo puberal é conhecida, sendo provavelmente de origem multifatorial, afetando mais intensamente as formas graves da doença, onde a anemia crônica e infecções de repetição estão presentes. As alterações displásicas do tecido ósseo e das cartilagens de crescimento inerentes a osteopetrose certamente desempenham um papel importante na baixa estatura.

Mineral metabolism in healthy geriatric dogs

To study mineral metabolism in geriatric dogs, parathyroid hormone, calcitriol, ionised calcium, phosphorus, blood urea nitrogen and creatinine were evaluated in 35 geriatric dogs (> 10 years) and in 20 young adult dogs (2–5 years). Parathyroid hormone levels were within the normal range in both groups, but values (mean ± SEM) were greater in the old dogs (34·8 ± 3·6 vs 21·2 ± 2·3 pg ml −1, P=0·005). Calcitriol and ionised calcium were similar in the two groups, and the values for both parameters were within the normal reference range. Plasma phosphorus levels were in the normal range in both groups but tended to be greater in the older dogs (P=0·09). While blood urea nitrogen was similar in the two groups, creatinine levels (mean ± SEM) were higher in the young dogs (82·2 ± 3·5 vs 101 ·7 ± 4·4 μmol litre −1). Even when the dogs were matched for weight, plasma creatinine concentration was still greater in the younger dogs. In conclusion, an increase in parathyroid hormone without changes in calcium, phosphorus and calcitriol has been identified in geriatric dogs.

Effect of calcium-channel blockers on calcium—phosphate metabolism in patients with end-stage renal disease

After EDTA-induced hypocalcaemia, healthy volunteers treated with diltiazem display more severe hyperparathyroidism than subjects on felodipine studied under identical conditions. Therefore patients with end-stage renal disease (ESRD) and severe secondary hyperparathyroidism might be particularly sensitive to this side-effect. To test this hypothesis, seven patients with ESRD on chronic haemodialysis (3 women and 4 men) with serum levels of intact PTH ranging from 204 to 675 pg/ml were studied both before and during the first 180 min of haemodialysis against a dialysate with low calcium concentration (0.75 mmol/l, n = 6 and 1 mmol/l, n = 1) under the following three experimental conditions: control, felodipine (10 mg/day) and diltiazem (120 mg b.i.d.). At onset of dialysis, plasma phosphorus level was higher on diltiazem (2.03 +/- 0.08 mM) than on felodipine (1.64 +/- 0.10, P < 0.02), and on the latter it was lower than in control condition (1.88 +/- 0.16, P < 0.02). As a probable consequence, blood ionized calcium concentration was lower on diltiazem (1.14 mM +/- 0.02, mean +/- SEM) than on felodipine (1.2 +/- 0.03, P < 0.05) or in control condition (1.17 +/- 0.01, NS). There was a trend for intact PTH to be higher on diltiazem (324 +/- 47 pg/ml) than on felodipine (246 +/- 55) or in control condition (305 +/- 49) and 1,25-dihydroxyvitamin D was higher indeed on diltiazem (6.70 +/- 0.92 pg/ml) than on felodipine (4.75 +/- 0.91, P < 0.02) or control (3.87 +/- 0.62, P < 0.05). Area under the curve PTH over the first 60 min of dialysis was higher by 16 +/- 7% on diltiazem than on felodipine (P < 0.05). While on diltiazem rather than on felodipine, patients with ESRD display higher plasma phosphorus levels, and slightly aggravate the degree of severity of hyperparathyroidism recorded during haemodialysis against low-calcium dialysate. The long-term effect of this new observation remains to be evaluated.

Effects of inclusion of microbial cultures in barley-based diets fed to laying hens

The effect of a mix of freeze dried Lactobacillus acidophilus plus Lactobacillus casei (2.3 × 10 8 colony forming units (cfu) kg −1 feed), or concentrates of Bacillus cereus (CICT-953) (10 9 cfu kg −1 feed), or Streptococcus faecium (CL-15) (1.5 × 10 9 cfu kg −1) on laying performance and mineral metabolism in White Leghorn hens was investigated in three 16-week experiments. A maize-barley (50/50) based diet (Experiment 1) or a barley based diet (Experiments 2 and 3) was used. The first experiment involved two treatments: a control diet and the same diet with L. acidophilus plus L. casei mixed culture. Supplementation improved hen day egg production ( P<0.01), feed conversion ratio ( P<0.01), egg weight ( P<0.05) and albumen quality ( P<0.05). Feed consumption and egg specific gravity were not influenced by the treatments. The second experiment also involved two treatments: an unsupplemented control diet and the same diet with B. cereus concentrate. Increased ( P<0.01) egg weight and albumen quality were observed in hens receiving the B. cereus culture. There were no significant differences in feed consumption, feed conversion ratio or egg specific gravity. The third experiment involved four dietary treatments: control diet; control diet with L. acidophilus plus L. casei mixed culture; control diet with B. cereus concentrate; or control diet with S. faecium concentrate. The L. acidophilus plus L. casei mix improved hen day egg production ( P<0.01), egg weight ( P<0.05), and albumen quality ( P<0.01). Feed consumption and feed conversion ratio were not affected by the addition of lactobacilli to the diet. Supplementation of B. cereus to the diet determined similar response to that indicated in Experiment 2. Birds receiving S. faecium produced greater egg mass ( P<0.01), egg weight ( P<0.01) and albumen quality ( P<0.01). Feed consumption, feed conversion ratio and egg specific gravity did not differ from the control group. Although calcium retention was not significantly affected by feeding the microorganisms cultures, it tended to improve by 2.4–4.2%. Addition of bacterial cultures to barley diet increased ( P<0.01) shell calcium. Plasma calcium, phosphorus, magnesium and zinc levels were similar to those of hens on the control diet. Feeding the S. faecium culture decreased ( P<0.05) serum copper. Laying hens fed an L. acidophilus plus L. casei mixed culture showed a decrease in serum iron ( P<0.01).

The renal PTH/PTHrP receptor is down-regulated in rats with chronic renal failure

Hypocalcemia, hyperphosphatemia, and resistance to the action of PTH are well characterized features in the setting of advanced chronic renal failure (CRF). Although the underlying mechanisms are ill-understood, clinical and experimental evidence points to both PTH receptor down-regulation and post-receptor abnormalities in their pathogenesis. In the present study we have examined the effect of advanced CRF in rats on the renal expression of PTH/PTHrP receptor (PTH-R). CRF was created by a standard two-step operation (5/6 nephrectomy). Four weeks thereafter, 19 uremic rats were compared with 23 sham-operated rats. Uremic rats had higher mean (+/- SD) plasma creatinine levels than control rats, 164 +/- 107 microM versus 43 +/- 5 microM, respectively. They also had higher plasma phosphorus and iPTH levels, 4.70 +/- 1.71 mM versus 2.59 +/- 0.37 mM and 561 +/- 336 versus 27 +/- 18 pg/ml, respectively. Mean plasma total calcium and blood ionized calcium were significantly lower in uremic than in control rats, 2.13 +/- 0.06 mM versus 2.61 +/- 0.10 mM and 1.07 +/- 0.11 versus 1.31 +/- 0.06 mM, respectively. Mean plasma calcitriol concentration was also significantly lower in uremic than in control rats, 39.8 +/- 14.6 and 80.4 +/- 15.2 pg/ml, respectively. Nine out of the 19 rats were examined for renal PTH-R gene expression.(ABSTRACT TRUNCATED AT 250 WORDS)