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Biomedical subjects

P Hardy

Publications and source records attributed to P Hardy.

At least 73 records · Page 4Linked to original sources
PubMed1999

Effects of early reduced light exposure on central visual development in preterm infants.

The aim of this study was to determine, in infants born at < or =29 weeks postmenstrual age until 32 weeks postmenstrual age, whether reduction to light stimulation by occlusion of eyes affected central visual development. The pattern visual-evoked potential responses at 41 and 51 weeks postmenstrual age and 3 y of age did not differ between infants subjected or not to ocular occlusion. Hence, an early marked reduction in light stimulation in preterm infants does not seem deleterious to visual development.

Age Factors↗
PubMed1999

Cyclooxygenase-2 plays a significant role in regulating the tone of the fetal lamb ductus arteriosus.

Nonselective cyclooxygenase (COX) inhibitors are potent tocolytic agents but have adverse effects on the fetal ductus arteriosus. We hypothesized that COX-2 inhibitors may not affect the ductus if the predominant COX isoform is COX-1. To examine this hypothesis, we used ductus arteriosus obtained from late-gestation fetal lambs. In contrast to our hypothesis, fetal lamb ductus arteriosus expressed both COX-1- and COX-2-immunoreactive protein (by Western analysis). Although COX-1 was found in both endothelial and smooth muscle cells, COX-2 was found only in the endothelial cells lining the ductus lumen (by immunohistochemistry). The relative contribution of COX-1 and COX-2 to PGE2 synthesis was consistent with the immunohistochemical results: in the intact ductus, PGE2 formation was catalyzed by both COX-1 and COX-2 in equivalent proportions; in the endothelium-denuded ductus, COX-2 no longer played a significant role in PGE2 synthesis. NS-398, a selective inhibitor of COX-2, was 66% as effective as the selective COX-1 inhibitor valeryl salicylate and the nonselective COX inhibitor indomethacin in causing contraction of the ductus in vitro. At this time, caution should be used when recommending COX-2 inhibitors for use in pregnant women.

Animals↗
PubMed1999

Developmentally increased cerebrovascular NO in newborn pigs curtails cerebral blood flow autoregulation.

We tested the hypothesis that a reduced ability of the newborn (1-2 d old) to autoregulate cerebral blood flow (CBF) during acute hypertension is contributed by an increased synthesis of nitric oxide (NO) from endothelial (e) and neuronal NO synthase (nNOS). As previously reported, CBF (measured by radiolabeled microsphere technique) in newborn pigs remained constant only between 50 and 90 mm Hg of mean arterial blood pressure. Treatment of newborn pigs with Nomega-monomethyl-L-arginine or specific nNOS inhibitors 7-nitroindazole monosodium, 3-bromo-7-nitroindazole, and 1-(2-trifluoromethylphenyl) imidazole extended the upper limit of CBF autoregulation as seen in saline-treated (control) juvenile (4-6-wk-old) animals. Cerebrovascular production of nitrite (stable NO oxidation product) in vivo was markedly increased during hypertension (mean arterial blood pressure > 90 mm Hg) in newborn but not in the juvenile pigs. Inhibition of NOS with Nomega-monomethyl-L-arginine, 7-nitroindazole monosodium, 3-bromo-7-nitroindazole, or 1-(2-trifluoromethylphenyl) imidazole prevented the hypertension-induced increase in nitrite levels. In addition, eNOS and nNOS protein expression and activity were 2- to 3-fold higher (p < 0.05) in the cerebral microvasculature of newborn than in the tissues of juvenile pigs. It is concluded that during acute hypertension, excess production of NO associated with increased activity of NOS curtails the upper limit of CBF autoregulation in the newborn subject; in addition, nNOS seems to serve a significant role in this important physiologic function.

Animals↗
PubMed1999

[Factors in the progression of renal insufficiency during the 2 years preceding the use of dialysis].

UNLABELLED: The respective contribution of sex, type of nephropathy, degree of proteinuria, blood pressure, protein and sodium daily intake, lipid profile, protidemia, hemoglobinemia, acidosis and CaPO4 product on the rate of renal failure progression is debated. The link between these parameters and the decrease of creatinine clearance, delta Ccr (according to Cockroft) was assessed in uni and multivariate analysis in a population of 49 patients (26 men, 23 women; age 60 +/- 15 years, weight 73 +/- 15 kg) selected out of 173 presently treated hemodialysis patients on the basis of availability of a quarterly follow-up for two years before starting dialysis. The patients were advised a moderate protein and salt restriction which could be retrospectively assessed (on urinary excretion of urea and sodium) at respectively 0.82 g/kg/day and 6.5 g/day. The two years delta Ccr was 14 +/- 14 ml/min. It was not different in men and women (specially when expressed in % of initial value). This decrease in Ccr was neither significantly different in glomerular disease (17 +/- 8, n = 14), diabetic nephropathy (12 +/- 6, n = 7), nephroangiosclerosis (15 +/- 8, n = 5), interstitial nephritis (12 +/- 10, n = 14), and PKD (11 +/- 12, n = 9). Patients with antihypertensive drugs (n = 42) had a faster progression than those without drugs (n = 7): delta Ccr = 15 +/- 14 vs 7 +/- 7 ml/min (p < 0.05) in spite of comparable blood pressure but with higher proteinuria. Linear regression of delta Ccr with the initial and two year averaged values of the quantitative parameters showed a significant positive link for both values with cholesterol, hemoglobin and proteinuria and a negative one with protidemia. A positive link was observed with the initial value of bicarbonate and the two year mean of diastolic and mean blood pressures. No link at all was observed with urea and Na excretion, CaPO4 product and triglycerides. Multiple regression disclosed a significant link only for protidemia (negative with both initial and two years averaged value), diastolic BP (only for the two year averaged value and hemoglobinemia (for the initial value). When the patients were classified according to a threshold value of their protidemia, DBP, hemoglobinemia, and cholesterolemia those with the combination of two risk factors of progression (pro-tidemia < 66 g/l, DBP > or = 90 mmHg, hemoglobinemia > 11 g/dl, proteinuria > 3g/d, CT > 5 mmol/l) had a significantly greater decrease of Ccr than those with the three other combinations at the exception of the association of low protidemia with DBP. CONCLUSION: 1. diastolic hypertension and low protidemia are the two most important factors predicting progression of renal failure; 2. a predictive synergy was furthermore pointed out between on one hand low protidemia and diastolic hypertension and on the other hand proteinuria and cholesterol; 3. on the contrary, anemia attenuates progression linked to low protidemia, diastolic hypertension, proteinuria and high cholesterol.

Acidosis↗
PubMed1999

Risk factors of renal failure progression two years prior to dialysis.

AIM: The respective contribution of sex, type of nephropathy, degree of proteinuria, blood pressure, protein and sodium daily intakes, blood lipid profile, protidemia, hemoglobinemia, acidosis and CaPO4 product on the rate of renal failure progression is debated. PATIENTS AND METHODS: The link between these parameters and the decrease of creatinine clearance, deltaCcr (according to Cockroft) was assessed in uni- and multivariate analysis in a population of 49 patients (26 women; age 60+/-15 years, weight 79+/-15 kg) selected out of 173 presently treated hemodialysis patients on the basis of availability of a quarterly follow-up for 2 years before starting dialysis. The patients were advised a moderate protein and salt restriction which could be retrospectively assessed (on urinary excretion of urea and sodium) at, respectively, 0.82 g/kg/day and 6.5 g/day. RESULTS: The 2-year deltaCcr was 14+/-14 ml/min. It was not different in men and women. This decrease in Ccr was neither significantly different in gomerular disease (17+/-8, n = 14), diabetic nephropathy (12+/-6, n = 7), nephroangiosclerosis (15+/-8, n = 5), interstitial nephritis (12+/-10, n = 14), and PKD (11 +/-12, n = 9). Patients with antihypertensive drugs (n = 42) had a faster progression than those without drugs (n = 7): deltaCcr = 15+/-14 vs 7+/-7 ml/min (p < 0.05) in spite of comparable blood pressure but with higher proteinuria. Linear regression of deltaCcr with the initial and 2-year averaged values of the quantitative parameters showed a significant positive link for both values with cholesterol, hemoglobine and proteinuria and a negative one with protidemia. A positive link was observed with the initial value of bicarbonate and the 2-year mean of diastolic and mean blood pressures. No link at all was observed with urea and Na excretion, CaPO4 product and triglycerides. Multiple regression disclosed a significant link only for protidemia (negative with both initial and 2-year averaged value), diastolic BP (only for the 2-year averaged value and hemoglobinemia (for the initial value). When the patients were classified according to a threshold value of their protidemia, DBP, hemoglobinemia, and cholesterolemia those with the combination of 2 risk factors of progression (protidemia > or = 66 g/l, DBP > or = 90 mmHg, hemoglobinemia > 11 g/dl, proteinuria > or = 3 g/d, CT > 5 mmol/l) had a significantly greater decrease of Ccr than those with the 3 other combinations at the exception of the association of low protidemia with DBP. CONCLUSION: Diastolic hypertension and low protidemia are the 2 most important factors predicting progression of renal failure. A predictive synergy was furthermore pointed out between low protidemia or diastolic hypertension with proteinuria and cholesterol. On the contrary anemia attenuates progression linked to low protidemia, diastolic hypertension, proteinuria and high cholesterol.

Anemia↗
PubMed1999

[Osteosynthesis under arthroscopic control of separated tibial plateau fractures. 26 case reports].

PURPOSE OF THE STUDY: Arthroscopic treatment of tibial plateau fractures may reduce morbidity compared to open articular surgery. But bony fixation is necessarily percutaneous and minimal. The purpose of our study was not only to assess immediate results but also long term functional and anatomic results after arthroscopic treatment of tibial plateau fractures, with special reference to radiographical results. MATERIAL AND METHODS: Twenty-six patients (mean age 42 years, range 18 to 70 years, 17 men, 9 women) were arthroscopically treated for a fresh tibial plateau fracture. According to Schatzker classification, there was 2 type I, 17 type II, 6 type III and 1 type IV. No type V or VI were treated in this series. The fixation device was: percutaneous cannulated screw in 23 cases, Kirchner wire in 2 cases, and bone cement filing of the fracture site in 1 case. We did not use cancellous bone graft but we used a hydroxyapatite plug in one case. There were 8 meniscal injuries: 2 underwent arthroscopic suture, 1 had partial meniscectomy and 5 were left in place. Twenty-six cases were suitable for immediate post op follow up. 19 were reviewed at long term. A clinical (Knee Society scoring system) and radiographical examination were done with an average follow-up of 32.7 months. RESULTS: There were no complications except one immediate postoperative septic osteoarthritis (case with hydroxyapatite plug) and one bony depression of the lateral tibial plateau at the fourth month. Passive motion of the knee started at 1.8 days postop with no pain. Mean flexion at 3 months was 130 degrees. At revision, the average score was: 94.1 for the knee, 94.7 for the function. In two cases we found early signs of osteoarthrosis. There were no secondary bony depression or significant valgus deformity on X-rays. CONCLUSION: Arthroscopic management of tibial plateau fractures allows a complete articular screening. Rapid rehabilitation, short hospital stay, and low rate of complications reduce morbidity. The long term results are as good as those with open surgical technique for the types of fracture that we have treated (type III and IV). A minimal, percutaneous osteosynthesis which was the only possibility under arthroscopic control, did not modify the anatomical results.

Adolescent↗
PubMed1999

Developmental regulation of endothelial nitric oxide synthase in cerebral vessels of newborn pig by prostaglandin E(2).

We investigated whether prostaglandins regulate endothelial nitric oxide synthase (eNOS) in the pig cerebral vasculature during the neonatal period. Prostaglandins, eNOS mRNA, eNOS protein, and NO production were higher in cerebral microvessels of newborn (1 day old) than in those of adult (6- to 8-month-old) pigs. The treatment of isolated cerebral microvessels of newborn animals with ibuprofen for 24 h reduced eNOS mRNA and nitrite production to levels in the adult; this effect of ibuprofen was prevented by concurrent treatment with prostaglandin (PG)E(2) analog 16,16-dimethyl-PGE(2), nonselective PGE(2) receptor analog 11-deoxy PGE(1), and prostaglandin EP(3) receptor agonists sulprostone and M&B 28,767 but was not modified by PGI(2) analog carbaprostacyclin, PGD(2), and EP(1) receptor agonist 17-phenyl trinor PGE(2). Correspondingly, 16, 16-dimethyl-PGE(2) and M&B 28,767 increased eNOS mRNA expression of adult microvessels to values in the newborn. Data similar to those with isolated cerebral vessels were obtained through histochemical analysis (NADPH-diaphorase positivity) of brain from newborn animals treated in vivo with ibuprofen in combination or not with sulprostone. Furthermore, substance P-induced NO-mediated cerebral vasorelaxation was decreased to adult values through the treatment of newborn pigs with ibuprofen; this effect was prevented by concomitant treatment with sulprostone. It is concluded that PGE(2) regulates eNOS in newborn pig cerebral microvessels via EP(3) receptors; this may be physiologically required during normal neurovascular development.

Age Factors↗
PubMed1999

[Arthroscopic meniscectomy with Ho-Yag laser versus mechanical meniscectomy. Mid-term results of a randomized prospective study of 80 meniscectomies].

INTRODUCTION: The theoretical advantages of the Ho-Yag laser make it the ideal instrument for current use in arthroscopic meniscectomy. Short term results showed less patient discomfort, rapid recovery and less post operative pain and swelling. The purpose of this single blind prospective randomized study was to compare the results of arthroscopic meniscectomy performed mechanically to those obtained with the Ho-Yag laser, with a minimum follow up of one year. MATERIALS AND METHODS: Eighty meniscectomies in 76 patients were included with a mean follow up of 19.5 months (extremes 12-35 months). The mean age was 42.5 years (extremes 18-65 years). The laser group included 39 patients while the mechanical group included 37 patients. In the Ho-Yag laser group, energy never exceeded 30 watts. During arthroscopic meniscectomy, no other surgical procedure was allowed i.e. chondroplasty, ligament surgery. Prior to arthroscopy, all patients underwent a clinical evaluation including: Pain and Lysholm score assessment. This was repeated in the post operative period at the 10th, 30th day and at last follow up. 37 patients also had a standard X ray at last follow up (anterior-posterior, lateral, and schuss views). RESULTS: No statistically significant difference was observed in global clinical results between both techniques. Even if mechanical meniscectomy showed better results, the laser remained best when used in degenerative medial meniscal tears with minimal cartilaginous lesions. In degenerative medial meniscal tears with severe cartilaginous lesions, mechanical meniscectomy showed significantly better results (p = 0.048). X ray control was normal in 47 p. 100 of the laser group and in 80 p. 100 of the mechanical group. The difference was statistically significant (p = 0.038). Narrowing of the joint space was observed in 45 p. 100 of laser group and in 18 p. 100 of mechanical group. Iterative arthroscopy was necessary in 4 cases (3 laser and 1 mechanical) for residual pain. Severe chondrolysis was present in 2 cases following laser meniscectomy. In the 2 other cases a complement of meniscectomy for residual lesions allowed good results. No bony necrosis was observed after laser meniscectomy. CONCLUSION: According to the results of this study and the high cost of the laser, we do not recommend the laser as a routine technique for arthroscopic meniscectomy.

Adolescent↗
PubMed1999

Effects of hyperbaric oxygen on aerobic performance in a normobaric environment.

The purpose was to examine the acute effects of a hyperbaric oxygen (HBO2) treatment on a) recovery following prolonged exercise and b) aerobic performance in a trained population. Subjects were six male and six female, trained runners with mean Vo2max values of 64.6 +/- 5.6 and 51.9 +/- 6.6 ml x kg(-1) x min(-1), respectively. Subjects performed four exercise-HBO2 conditions in random order: a) control, b) exercise-no HBO2, c) no exercise-HBO2; and d) exercise-HBO2. Exercise was a 90-min run at 75-80% of Vo2max x HBO2 treatments consisted of breathing 95% O2 at 2.5 atm abs for 90 min. At the end of each condition, aerobic performance was assessed with a VO2max test and by the oxygen cost of running on a treadmill at three submaximal velocities. Recovery was not enhanced following a single HBO2 treatment at 2.5 atm abs for 90 min, nor did it alter submaximal or maximal running performance.

Adult↗
PubMed1998

One day survey by the Mental Health Act Commission of acute adult psychiatric inpatient wards in England and Wales.

OBJECTIVES: To provide (via the Mental Health Act Commission's "national visit") empirical evidence on ward occupancy levels, use of the Mental Health Act 1983, nurse staffing, and care of female patients on acute adult psychiatric wards. DESIGN: One day survey of a stratified random sample. SETTINGS: 119/250 (47%) acute adult psychiatric inpatient units in England and Wales. SUBJECTS: End sample of 263 acute psychiatric inpatient wards. MAIN OUTCOME MEASURES: Ward occupancy rates; number of patients detained under the Mental Health Act and proportion "absent without leave"; nurse staffing levels, skill mix, and vacancies;proportion of women with self contained, women-only facilities. RESULTS: Mean ward occupancy was 99% (95% confidence interval 97% to 102%). A ward mean of 30% (28% to 32%) of patients were detained under the Mental Health Act; of all detained patients, 1% (1% to 2%) were absent without leave. A ward mean of 0.3 (0.29 to 0.31) nurses were on duty per patient at the time of the visit. An estimated ward mean of 31% (30% to 32%) of nurse staffing may have been through casual contracts--higher in inner (48% (43% to 53%)) and outer London (45% (41% to 48%)). On 26% (21% to 32%) of wards, there were no nurses interacting with patients. A ward mean of 36% (30% to 41%) of female patients had self contained, women-only facilities. CONCLUSIONS: Attention should focus on improving the quality of acute inpatient psychiatric care as well as of community care.

Adolescent↗
PubMed1998

A major role for prostacyclin in nitric oxide-induced ocular vasorelaxation in the piglet.

We studied the mechanisms of retinal and choroidal vasorelaxation elicited by nitric oxide (NO) using piglet eyes. The NO donors sodium nitroprusside (SNP) and diethylamine-NONOate caused comparable concentration-dependent relaxation that was partially (approximately 40%) attenuated by the guanylate cyclase inhibitors methylene blue and LY83583 and reduced to a lesser extent (approximately 25%) by the inhibitor of cGMP-dependent kinase, KT 5823. In contrast, NO-induced dilatation (by NO donors and endogenous NO after stimulation with bradykinin) was substantially (approximately 70%) diminished by the KCa channel blockers tetraethylammonium (TEA), charybdotoxin, and iberiotoxin; by the cyclooxygenase inhibitors indomethacin and ibuprofen; by the prostaglandin I (PGI2) synthase inhibitor trans-2-phenyl cyclopropylamine (TPC); and by the removal of endothelium; whereas relaxation of endothelium-denuded vasculature to SNP was unaltered by indomethacin, TPC, and charybdotoxin but was nearly nullified by methylene blue and the Kv channel blocker 4-aminopyridine. NO donors significantly increased PGI2 synthesis and the putative PGI2 receptor-coupled second messenger cAMP, from ocular vasculature (retinal microvessels and choroidal perfusate), and this increase in PGI2 formation was markedly reduced by TPC, tetraethylammonium, charybdotoxin, and/or the removal of endothelium, but it was only slightly reduced by methylene blue and LY83583. Also, SNP and KCa channel openers NS1619 and NS004 caused an increase in PGI2 synthesis in cultured endothelial cells, which was virtually abolished by KCa blockers. Finally, vasorelaxation to a cGMP analogue, 8-bromo cGMP, and protein kinase G stimulant beta-phenyl-1,N2-etheno-8-bromoguanosine 3':5'-cyclic monophosphate was mostly Kv dependent and, in contrast to NO, largely unrelated to PGI2 formation. In conclusion, data indicate that NO-induced ocular vasorelaxation is partly mediated by cGMP through its action on smooth muscle, and more importantly, by stimulating PGI2 formation of endothelial origin via a mechanism mostly independent of guanylate cyclase, which involves the opening of a KCa channel.

Animals↗
PubMed1998

Formation of isoprostane-like compounds (neuroprostanes) in vivo from docosahexaenoic acid.

F2-isoprostanes are prostaglandin F2-like compounds that are formed nonenzymatically by free radical-induced oxidation of arachidonic acid. We explored whether oxidation of docosahexaenoic acid (C22:6omega3), which is highly enriched in the brain, led to the formation of F2-isoprostane-like compounds, which we term F4-neuroprostanes. Oxidation of docosahexaenoic acid in vitro yielded a series of compounds that were structurally established to be F4-neuroprostanes using a number of mass spectrometric approaches. The amounts formed exceeded levels of F2-isoprostanes generated from arachidonic acid by 3.4-fold. F4-neuroprostanes were detected esterified in normal whole rat brain and newborn pig cortex at a level of 7.0 +/- 1.4 ng/g and 13.1 +/- 8 ng/g, respectively. Furthermore, F4-neuroprostanes could be detected in normal human cerebrospinal fluid and levels in patients with Alzheimer's disease (110 +/- 12 pg/ml) were significantly higher than age-matched controls (64 +/- 8 pg/ml) (p < 0.05). F4-neuroprostanes may provide a unique marker of oxidative injury to the brain and could potentially exert biological activity. Furthermore, the formation of F4-neuroprostane-containing aminophospholipids might adversely effect neuronal function as a result of alterations they induce in the biophysical properties of neuronal membranes.

Alzheimer Disease↗
PubMed1998

Aseptic avascular necrosis of the femoral condyles in renal transplant patients: clinical and radiological aspects on 69 knees.

The purpose of this study was to analyze clinical and radiological aspects of aseptic avascular necrosis (AVN) of the femoral condyles in renal transplant patients. Forty-five renal transplant patients were followed between 1971 and 1993, and 69 knees have been studied. The immunosuppressive protocol comprised in all cases corticosteroids, with aziathioprine and since 1983 cyclosporin in 80% of patients. Episodes of rejection were treated with bolus doses of methylprednisolone. In 53.3% of patients, both knees were involved. The necrosis was bicondylar in 60.8% of knees. In the case of an unicondylar lesion, the lateral condyle was involved in 24.7% of knees vs 14.5% for the medial condyle. Symptoms occurred on average 4.9 years after transplantation (range 3 months-10.5 years). This period appeared significantly shorter for patients who had suffered an episode of rejection. In only 24.4% of patients was the knee involvement isolated. Pain was the initial symptom for 83% of patients. Other symptoms included locked knee (20.7%), effusion (49.2%), instability (14.5%), and loss of motion (15.9%). The diagnosis was established by standard radiographs, and in 8 patients by magnetic resonance imaging. Aseptic AVN of the femoral condyles in renal transplant patients is not rare even if it is less frequent than femoral head necrosis. Medication with corticosteroids is the main risk factor.

Adolescent↗
PubMed1998

Expression of cyclooxygenases in ductus arteriosus of fetal and newborn pigs.

OBJECTIVE: We studied the ontogeny of the expression of cyclooxygenase-1 and cyclooxygenase-2 in the ductus arteriosus and evaluated their functional significance. STUDY DESIGN: The expression of cyclooxygenase-1 and cyclooxygenase-2 was studied in ductus arteriosus of fetal (at approximately 75% gestation) and term newborn pig. Effects of selective inhibitors of cyclooxygenase-1 and cyclooxygenase-2 on ductal patency were evaluated by Doppler ultrasonography. RESULTS: Ductus arteriosus of the fetus expressed virtually only cyclooxygenase-1 immunoreactive protein and activity. In contrast, the ductus of the term newborn pig (<45 minutes old) contained proteins of both cyclooxygenase-1 and cyclooxygenase-2, but the latter contributed to >90% of prostaglandin E2 formation. The selective cyclooxygenase-2 inhibitor DuP697 reduced prostaglandin E2 levels in the ductus arteriosus, albeit not in plasma, but did not affect ductal patency in the newborn pig (<1(1/2) hours old); in contrast, the cyclooxygenase-1 inhibitor valeryl salicylate, like indomethacin, markedly reduced levels of prostaglandin E2 in the plasma and ductus arteriosus and caused significant constriction of the ductus arteriosus. CONCLUSION: The ductus arteriosus of the term newborn pig, in contrast to that of the fetus, expresses cyclooxygenase-2, but circulating prostaglandins, arising mostly from cyclooxygenase-1, seem to exert the major control on ductal patency in vivo. Our data suggest that cyclooxygenase-2 inhibitors might be better alternatives for the fetus than nonselective cyclooxygenase blockers if indicated for maternal conditions such as inflammation or for tocolysis.

Animals↗
PubMed1998

Glomus tumor of the fat pad.

The authors report an exceptional glomus tumor location in Hoffa's ligament in a 65-year-old man. Based on this observation and a literature review, the authors provide the clinical and radiographic diagnostic appearances of this type of tumor. Surgical removal of the tumor achieved immediate disappearance of knee pain. Histological examination of the tumor has established the definitive diagnosis.

Adipose Tissue↗
PubMed1998

Role of calcium carbonate administration timing in relation to food intake on its efficiency in controlling hyperphosphatemia in patients on maintenance dialysis.

A study has claimed that at an equal elemental calcium dose, CaCO3 was not less but equally as efficient in controlling predialysis hyperphosphatemia as calcium acetate, provided both calcium salts were ingested 5 min before meals instead of during meals because the higher acidity of the fasting gastric juice would allow for better dissociation of CaCO3. However, this study did not directly demonstrate that the efficiency of CaCO3 in controlling hyperphosphatemia was actually greater when it was administered before a meal than during a meal. To examine this point, we performed a 3 month randomized crossover trial in 12 reliable and stable patients maintained on chronic hemodialysis. Their plasma concentrations of calcium, protein, phosphate, bicarbonate, urea, and creatinine were measured before the first dialysis of each week and the amount of intact parathyroid hormone (PTH) at the beginning and at the end of each of the 3 months. Comparison of the plasma concentrations measured during the 2 modes of administration showed no significant differences in creatinine, urea, bicarbonate, or intact PTH. The mean (+/-SD) plasma concentration of PO4 was not significantly lower (1.88+/-0.50 vs. 1.74+/-0.41 mM) whereas the corrected level of plasma Ca was significantly lower (2.30+/-0.17 vs. 2.38+/-0.16 mM; p < 0.04) when CaCO3 was given before meals than during meals. In conclusion, the administration of CaCO3 before a meal does not increase its efficiency in controlling hyperphosphatemia because the level of plasma PO4 was actually slightly higher with this timing of administration whereas the comparison of the creatinine and urea levels suggested a stability of phosphate intake and the comparison of the PTH and bicarbonate levels suggested the stability of osteolysis and of the transcellular membrane shift of phosphate. Also, administration of CaCO3 before a meal is associated with significantly lower plasma corrected calcium, suggesting less absorption of calcium, which may be an advantage but only in hypercalcemic patients. There is no reason other than the prevention of its hypercalcemic effect to recommend the administration of CaCO3 just before meals rather than during meals.

Absorption↗
PubMed1998

Inhibition of gastric secretion by omeprazole and efficiency of calcium carbonate on the control of hyperphosphatemia in patients on chronic hemodialysis.

Contradictions exist in the literature regarding the effect of gastric secretion inhibition on phosphate absorption. In healthy controls, omeprazole would decrease the hyperphosphatemia or the hyperphosphaturia induced by an acute phosphate load, suggesting an inhibition of phosphate absorption. In chronic hemodialysis patients, gastric hypersecretion is associated with hyperphosphatemia, but inhibition of gastric hypersecretion by ranitidine in those receiving calcium carbonate (CaCO3) as a phosphate binder would paradoxically exacerbate their hyperphosphatemia. Because of these conflicting observations, we performed an open crossover study on 16 chronic stable hemodialyzed patients with a daily mean intake of 9.4+/-4 g of CaCO3, and we compared the plasmatic predialysis levels of phosphate, calcium, protides, bicarbonates, intact parathyroid hormone (PTH), urea, and creatininemia during 2 successive periods of 2 months, the first one without omeprazole and the second one with 20 mg omeprazole intake in the morning. Phosphatemia increased with omeprazole but not significantly from 1.80+/-0.38 to 1.89+/-0.42 mM whereas corrected calcemia decreased significantly (p = 0.04) from 2.41+/-0.18 to 2.36+/-0.16 mM as did bicarbonatemia from 26.7+/-3.5 to 25.7+/-3.1 mM (p < 0.05). No change in creatininemia or in blood urea was observed, suggesting the stable efficiency of dialysis as well as the stable intakes of protein and therefore of phosphate during the two study periods. In conclusion, inhibition of gastric secretion by omeprazole increases the plasmatic phosphate predialytic level but in a nonsignificant way. This increase may be explained by a slight but significant concomitant decrease of calcemia and bicarbonatemia. These results do not support the phosphate binding efficiency of CaCO3 being decreased by the inhibition of gastric acid secretion.

Absorption↗