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P Joffe

Publications and source records attributed to P Joffe.

At least 19 recordsLinked to original sources
PubMed2000

Quantification of gadodiamide as Gd in serum, peritoneal dialysate and faeces by inductively coupled plasma atomic emission spectroscopy and comparative analysis by high-performance liquid chromatography.

An inductively coupled plasma atomic emission spectroscopy (ICP-AES) method for determination of gadodiamide as Gd in serum, peritoneal dialysate and faeces was developed. The within-day and between-day precision for determination of Gd in serum and peritoneal dialysate were 0.60-2.9 and 1.8-4.4%, respectively, and the accuracy was 98.0-99.3%. The quantification limits in serum and peritoneal dialysate were 6.5 and 1.6 microM Gd, respectively. The within-day and between-day precision determination of gadolinium in faeces were 1.0-5.3 and 2.2-7.9%, respectively, and the accuracy was 104-116%. The quantification limit was 11 nmol Gd/g dry weight. For the high-performance liquid chromatography (HPLC) method, the within-day precision in determination of gadodiamide in peritoneal dialysate was 1.2% and the accuracy was 103%. The quantification limit was 0.9 microM Gd. Comparative analysis of gadodiamide in serum and peritoneal dialysate from severely impaired renal patients by ICP-AES and HPLC revealed no metabolism of chelator or transmetallation of gadolinium, even in samples obtained as long as 7 days after dosing. Furthermore, the ICP-AES determination of Gd in faeces allows for the determination of faeces content of Gd corresponding to less than 0.1% of a clinical dosage of a Gd-based contrast medium.

Chromatography, High Pressure Liquid↗
PubMed1999

Healthcare systems--an international review: an overview.

Based on the source of their funding, three main models of healthcare can be distinguished. The first is the Beveridge model, which is based on taxation and has many public providers. The second is the Bismarck 'mixed' model, funded by a premium-financed social insurance system and with a mixture of public and private providers. Finally, the 'Private Insurance model' is only in existence in the US. The present report explores the impact of these healthcare models on the access to, quality and cost of healthcare in selected European countries. Access is nearly 100% in countries with a public provider system, while in most of the 'mixed' countries, the difference from 100% is made up by supplementary private insurance. No differences are seen between public and mixed provider systems in terms of quality of care, despite the fact that the countries with the former model spend, in general, less of their Gross National Product on healthcare. The Private Insurance/private provider model of the US produces the highest costs, but is lowest in access and is close to lowest ranking in quality parameters.

Delivery of Health Care↗
PubMed1998

Single-dose pharmacokinetics of citalopram in patients with moderate renal insufficiency or hepatic cirrhosis compared with healthy subjects.

OBJECTIVE: To compare the pharmacokinetics of the antidepressant citalopram and its metabolites demethylcitalopram and didemethylcitalopram in subjects with moderate renal insufficiency and subjects with hepatic cirrhosis with that in healthy subjects. METHODS: Pharmacokinetic parameters from three individual, open-label, phase I trials were derived following single oral or intravenous citalopram dose (40 mg) to healthy subjects and a single oral dose (20 mg) to patients. Serum and urine concentrations of citalopram and metabolites were determined using a validated HPLC method. RESULTS: The absolute bioavailability of citalopram tablets in healthy subjects was 80%. The renal clearance was a minor component (<20%) of the total elimination of citalopram. Serum Cmax and t(max) for citalopram were essentially unaffected by the occurrence of renal or hepatic disease. In comparison with healthy subjects, renal impairment was associated with a significant reduction in the renal elimination of citalopram and its two metabolites and a slight prolongation of serum citalopram t1/2 (49.5 h vs 36.8 h in healthy subjects). Cirrhosis resulted in significant decrease in citalopram CLoral (0.21 vs 0.331 x h(-1) x kg(-1) in healthy subjects) and increase in Vz x f(-1) with an approximately twofold increase in t1/2 (83.4 h vs 36.8 h in healthy subjects). Indices of renal (creatinine or 51Cr-EDTA clearances) and hepatic (galactose elimination capacity or Child-Pugh score) function were poor predictors of the changes in the pharmacokinetics of citalopram and its metabolites in these populations. CONCLUSION: No reduction of citalopram dosage is warranted in patients with moderately impaired renal function. However, that may not apply for patients with severe renal failure. In patients with impaired hepatic function, prescription of a lower dosage of citalopram may be appropriate.

Administration, Oral↗
PubMed1998

Pharmacokinetics of gadodiamide injection in patients with severe renal insufficiency and patients undergoing hemodialysis or continuous ambulatory peritoneal dialysis.

RATIONALE AND OBJECTIVES: The authors performed this study to evaluate the pharmacokinetics, dialysability, and safety of gadodiamide injection in patients with severely reduced renal function not treated with renal replacement therapy and patients undergoing hemodialysis or continuous ambulatory peritoneal dialysis. MATERIALS AND METHODS: Twenty-seven patients--nine with severely reduced renal function (glomerular filtration rate, 2-10 mL/min), nine undergoing hemodialysis, and nine undergoing continuous ambulatory peritoneal dialysis--were followed up for 5, 8, and 22 days, respectively, after receiving gadodiamide injection (0.1 mmol per kilogram body weight). RESULTS: Gadodiamide injection caused no changes in renal function. In patients with severely reduced renal function, the elimination half-life of gadodiamide injection was prolonged (34.3 hours +/- 22.9) compared with data in healthy volunteers (1.3 hours +/- 0.25). An average of 65% of the gadodiamide injected was eliminated during a hemodialysis session. After 22 days of continuous ambulatory peritoneal dialysis, 69% of the total amount of gadodiamide was excreted; this reflects the low peritoneal clearance. In all patients, no metabolism or transmetallation of gadodiamide was found. There were no contrast material-related adverse events. CONCLUSION: Gadodiamide is dialysable and can safely be used in patients with severely impaired renal function or those undergoing hemodialysis or continuous ambulatory peritoneal dialysis. No precautions to increase the elimination are necessary.

Adult↗
PubMed1996

Staphylococcus aureus carriage and infections among patients in four haemo- and peritoneal-dialysis centres in Denmark. The Danish Study Group of Peritonitis in Dialysis (DASPID).

A three-month prospective surveillance study was undertaken in four dialysis centres to establish the prevalence of Staphylococcus aureus carriage in a Danish population of patients on haemodialysis (HD) or on continuous ambulatory peritoneal dialysis (CAPD). General data such as sex, age, diagnosis, number of months in dialysis, hospital and ward were registered on a precoded form. Standardized nose and four skin swabs (axillae, groins, perineum) were performed on the first day of the survey. After one and two months, nose swabs were collected. Infections were registered and cultures were sent for phage-typing together with the S. aureus strains isolated from the swabs; 59.5% of HD patients and 51.2% of CAPD patients carried S. aureus. Permanent carriage was most frequent (P < 0.00009), primarily in the nose (44.0 and 34.9%, respectively in HD and CAPD). Skin carriage alone was rare (2.4 and 4.7%). Approximately one third (36.6 and 40.7%) of infections were caused by S. aureus. Although diabetics were not significantly more frequent carriers (60.5%) than non-diabetics (55.0%), the incidence of infection was much higher (26.3% vs. 10.3%, P = 0.004). In CAPD, peritonitis and tunnel/exit-site infections predominated (81.4%), often caused by S. aureus (34.8%). More than two thirds of the infections in HD patients were related to intravascular catheterization. The most serious infection was septicaemia, in all cases due to S. aureus. S aureus infections occurred significantly more frequently among carriers (P = 0.005), and more than half the patients were infected by the same or possibly the same strain as they carried in the nose or on skin. Different regimens for the elimination of S. aureus carriage in dialysis patients are discussed. A policy for risk assessment of patients should be developed, and the elimination of S. aureus carriage before dialysis should be encouraged. Controlled trials comparing the cost-effectiveness of recommended regimens to eliminate carriage in HD/CAPD patients are needed. Nose swabs are reliable indicators of carriage in dialysis patients.

Carrier State↗
PubMed1996

Aspects of osseous, peritoneal and renal handling of bisphosphonate during peritoneal dialysis: a methodological study.

The accumulation of methylene bisphosphonate (MBP) in increased bone turnover is an index of the total skeletal turnover. Accordingly, a model has been described where uptake of the osseous tracer can be estimated, regardless of renal function. In the present study, the model was adapted to continuous ambulatory peritoneal dialysis (CAPD). The aims were: to assess the kinetics of 99m-technetium MBP (99mTc-MBP) in CAPD, and to evaluate the correctness of the assumption that the peritoneal and renal clearances of 99mTc-MBP equal the total plasma clearance of 51-chromium ethylenediamine tetra-acetic acid (51Cr-EDTA). Eight patients on CAPD were studied cross-sectionally. The mean plasma clearances of 99mTc-MBP and 51Cr-EDTA in the steady state (4h) were 38.2 and 12.2 ml min-1 (p < 0.01), the peritoneal clearances (0-4 h) were 5.2 and 7.2 ml min-1 (p < 0.01), and the renal clearances (0-4 h) were 2.5 and 2.8 ml min-1 (not significant), respectively. The bone bisphosphonate clearance (BBC) at steady state was 26.0 ml min-1, a value which was significantly higher than that at infinity (16.5 ml min-1, p < 0.01). We conclude that the assumption that the sum of peritoneal and renal clearances of 99mTc-MBP equal the clearances of 51Cr-EDTA is correct from a clinical point of view. We found that the uptake of the tracers in soft tissue and the renal handling of 51Cr-EDTA and 99mTc-MBP are also similar. The differences between the clearance values for 51Cr-EDTA and 99mTc-MBP may be explained by their different molecular weight. The differences in the BBCs at infinity and at steady state are most probably due to late recirculation of MBP from the bone compartment. Hence, the BBC technique can be applied in the CAPD setting.

Adult↗
PubMed1996

Can bone histomorphometry be predicted by clinical assessment and noninvasive techniques in peritoneal dialysis?

In an attempt to evaluate whether bone histology could be predicted by clinical assessment and noninvasive techniques in patients on peritoneal dialysis, bone histomorphometry was correlated with symptoms of renal osteodystrophy, serum bone markers and parathyroid hormone (PTH) as well as radiographs and forearm osteodensitometry (bone mineral content, BMC). No correlations were found between clinical symptoms, biochemical markers, radiographic bone surveys, BMC measurements, and bone diagnosis. Serum 1,25-(OH)2D3 correlated negatively with the intracortical resorption and the degree of osteoporosis. No other correlations were seen between the serum markers measured, PTH and the radiographic parameters. Alkaline phosphatase correlated negatively with mineralization lag time and positively with eroded surface, mineral appositional rate, tetracycline-labelled surface and bone formation rates. HCO-3 correlated negatively with osteoid thickness and osteoid surface. Ca2+ correlated with osteoid surface, osteoid volume and cortical thickness. Mg correlated with the duration of azotemia, cortical porosity and bone aluminum content, while serum phosphate correlated with the mineral appositional rate. Osteocalcin and PTH correlated with osteoid thickness, the mineral appositional rate, tetracycline-labelled surface, the adjusted apposition rate, mineralization lag time and the bone formation rates. BMC measurements correlated with PTH and Ca2+ and inversely with sex and trabecular bone volume, osteoid thickness, osteoid surface, osteoid volume, eroded surface, osteoclast surface, tetracycline-labelled surface and the bone formation rates. Seven of the histomorphometric parameters correlated significantly with the radiological bone features. However, the clinical assessment and the serum markers of bone metabolism were of limited value. Thus, bone histology cannot be comprehensively predicted by non-invasive methods, although radiographs and forearm osteodensitometry provided some valuable information.

Adult↗
PubMed1996

[Copper in the drinking water--cause of gastrointestinal symptoms?].

This suspicion has been raised on the basis of investigations done mainly in Sweden. The copper originates from the copper pipelines inside the houses, and the concentration is highest in newly built houses and in the morning, when the water has been unstirred in the lines over night. The literature concerning the metabolism and toxicology of copper is presented, and it is concluded, that sufficient investigations are missing.

Adult↗
PubMed1995

Parameter estimation in six numerical models of transperitoneal transport of potassium in patients undergoing peritoneal dialysis.

The mechanisms of transperitoneal potassium transport during peritoneal dialysis were evaluated by validation of different mathematical models. The models were designed to elucidate the presence or absence of diffusive, non-lymphatic convective and lymphatic convective solute transport. Experimental results were obtained from 26 non-diabetic patients undergoing peritoneal dialysis. The validation procedure demonstrated that models including both diffusive and non-lymphatic convective solute transport were superior to the other models. Lymphatic convective solute transport was not identifiable. Furthermore, it was demonstrated experimentally that the equilibrium distribution of potassium between plasma water and dialysate did not differ from a Donnan equilibrium, although the precondition of the Donnan equilibrium was not fulfilled, i.e. the volumes on each side of the membrane were not constant and dialysate was not an ultrafiltrate of plasma.

Adult↗
PubMed1995

An evaluation of twelve nested models of transperitoneal transport of urea: the one-compartment assumption is valid.

Models of transperitoneal urea transport are generally based on the one-compartment assumption, i.e. that the plasma water urea concentration in the peritoneal capillary bed is equal to the plasma water urea concentration in the peripheral veins. The aim of this study was to investigate the mechanism(s) of transperitoneal urea transport and to test the one-compartment assumption for urea. A total of 12 nested models were formulated and validated on the basis of experimental results obtained from 23 non-diabetic patients undergoing peritoneal dialysis. The validation procedure demonstrated that transperitoneal transport of urea probably involves diffusion, non-lymphatic convection and lymphatic convection. It was furthermore demonstrated that the inclusion of lymphatic convection changes the mass transfer area coefficient considerably. Finally, no deviation from the one-compartment assumption was demonstrated by our results.

Adult↗
PubMed1995

Collagen markers in peritoneal dialysis patients.

Possible relationships between the dialysate-to-plasma creatinine equilibration ratio (D/Pcreatinine 4 hour), duration of peritoneal dialysis treatment, number of peritonitis episodes, and mass appearance rates of three connective tissue markers [carboxyterminal propeptide of type I procollagen (PICP), aminoterminal propeptide of type III procollagen (PIIINP), and carboxyterminal telopeptide of type I collagen (ICTP)] were studied in 19 nondiabetic peritoneal dialysis patients. The absence of correlation between the mass appearance rates of the markers and the duration of dialysis treatment as well as the number of peritonitis episodes supports the concept that peritoneal dialysis does not cause persistent changes in the deposition and degradation rates of collagen. A correlation between the D/Pcreatinine 4 hr and the PICP mass appearance rates was found. Since it is unlikely that transperitoneal transport alone is responsible for the appearance of PICP in dialysate, this might reflect an association between a large peritoneal surface area and the amount of submesothelial connective tissue.

Adult↗
PubMed1995

Bidirectional peritoneal transport of albumin in continuous ambulatory peritoneal dialysis.

The present study was undertaken in order to assess bidirectional peritoneal kinetics of albumin after simultaneous i.v. and i.p. injection of radioiodinated albumin tracers (125I-RISA and 131I-RISA) in eight clinically stable uraemic patients undergoing continuous ambulatory peritoneal dialysis (CAPD). The plasma volume, intravascular albumin mass (IVM), and overall extravasation rate of albumin were not significantly different from that found in healthy controls. Albumin flux from the plasma into the peritoneal cavity was 3.71 +/- 0.82 (SD) mumol/h, which was only 3% of the overall extravasation rate (137 +/- 52 mumol/h). Albumin flux from the peritoneal cavity into the plasma was substantially lower (0.22 +/- 0.07 mumol/h, P < 0.01). The net peritoneal accumulation of the albumin from plasma over 4 h was 14 +/- 3.2 mumol, which was significantly lower than the intraperitoneal albumin mass at the end of the dialysis (54 +/- 19 mumol, P < 0.01). This indicates that only about 25% of the albumin loss during CAPD occurs directly from the plasma. The initial osmotic net filtration was 508 +/- 302 ml. The volume flow equivalent to the albumin flux was 6.3 +/- 1.5 ml/h into the peritoneal cavity and 7.8 +/- 1.9 ml/h back into the plasma. Although minor, as compared to the osmotic net filtration (508 ml), the albumin flux equivalent volume (31.2 ml) exceeded the steady state filtration (25.2 ml) significantly (P < 0.01) during the 4 h investigation. In conclusion, albumin flux into the peritoneal cavity is small compared to the overall extravasation rate, but our results suggest that CAPD loss of albumin predominantly occurs from the subperitoneal interstitial space and only to a minor degree directly from the plasma. Albumin flux equivalent volume flow is relatively small and most probably represents peritoneal lymph drainage.

Adult↗
PubMed1995

Type I procollagen propeptide in patients on CAPD: its relationships with bone histology, osteocalcin, and parathyroid hormone.

Serum procollagen type I carboxyterminal propeptide (PICP) has been shown to be a useful marker of bone formation in patients undergoing haemodialysis. However, PICP levels has not been evaluated in depth in patients maintained on continuous ambulatory peritoneal dialysis (CAPD). Therefore serum and dialysate levels of PICP, its peritoneal clearance (Clp), mass transfer (MTp), and its possible relationship with osteocalcin, parathyroid hormone (PTH), and bone histomorphometry were studied in a group of CAPD patients. Serum PICP was just above the normal range with significant amounts detected in the dialysate but no correlations were found between levels of serum PICP, dialysate PICP, and Clp-PICP. One patient with systemic lupus and osteitis fibrosa had extraordinarily high serum and dialysate levels of PICP. The patient later developed sclerosing peritonitis. No associations were seen between serum PICP and Clp-PICP and any of the 18 bone histomorphometric parameters evaluated. Dialysate level of PICP correlated negatively with mineral appositional rate (r = -0.62, P < 0.01) and mineralization lag time (r = 0.64, P < 0.01). MTp-PICP correlated positively with mineral appositional rate (r = 0.65, P < 0.01). Serum osteocalcin and serum PTH levels did not correlate to serum, dialysate, Clp or MTp measurements of PICP. These results suggest that measurements of PICP in CAPD patients do not give substantial information as an non-invasive marker of bone histology.

Adult↗
PubMed1994

[Giant fecaloma].

A case of a giant faecaloma of the sigmoid colon secondary to surgery is reported. The predisposing factors, the diagnostic and therapeutic approaches are discussed.

Aged↗
PubMed1994

Osteocalcin: a non-invasive index of metabolic bone disease in patients treated by CAPD.

Serum osteocalcin has been found to correlate with bone formation. However, present literature gives only limited data on osteocalcin and bone histomorphometry in patients undergoing peritoneal dialysis. This study assessed serum osteocalcin, dialysate osteocalcin, peritoneal clearance of osteocalcin (Clp-osteocalcin) and mass transfer of osteocalcin (MTp-osteocalcin), and evaluated relationships between these values and bone histomorphometry. Eighteen patients were treated by continuous ambulatory peritoneal dialysis (CAPD). Bone biopsies, serum and dialysate osteocalcin, serum levels of parathyroid hormone, alkaline phosphatase, aluminum, phosphate, Ca2+ and vitamin D3 metabolites were measured at the start and in 10 of the patients a year later. Serum osteocalcin was found to be elevated. Osteocalcin was detected in the dialysate resulting in significant values of Clp-osteocalcin and MTp-osteocalcin. Serum and dialysate levels of osteocalcin correlated significantly (r = 0.66, P < 0.001) and like MTp-osteocalcin with serum levels of alkaline phosphatase and PTH. Histomorphometry showed that osteitis fibrosa was the predominant bone disease detected. Serum concentration of osteocalcin correlated with osteoid thickness, eroded and osteoclast surfaces, aluminum staining, and some of the bone dynamic parameters. Dialysate osteocalcin, MTp-osteocalcin, PTH and alkaline phosphatase correlated with practically the same histomorphometric parameters as serum osteocalcin. No correlations were seen between Clp-osteocalcin and any histomorphometric parameters. Serum osteocalcin was elevated above the normal range, and significant positive correlations between serum osteocalcin and bone formation parameters were found. Serum osteocalcin correlated with almost the same histomorphometric parameters as PTH. Thus, serum levels of PTH and osteocalcin gave additional information to one another as non-invasive parameters in this group of patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Acute effect of oral, intraperitoneal, and intravenous 1 alpha-hydroxycholecalciferol on markers of bone metabolism.

OBJECTIVE: To study the acute effect of 1 alpha-hydroxycholecalciferol (1 alpha-OHD3) on serum levels of alkaline phosphatase, Ca2+, osteocalcin, parathyroid hormone (PTH), phosphate and type I and III procollagens (PICP and PIIINP respectively) in patients undergoing peritoneal dialysis. Also, 1,25-(OH)2D3 was measured. DESIGN: Single doses of 1 alpha-OHD3 (80 ng/kg body wt) were given in randomized cross-over fashion, orally, intraperitoneally (i.p.) and intravenously (i.v.) on three occasions. Blood was sampled at 0, 1, 6, 12, and 24 h after administration of 1 alpha-OHD3. MAIN RESULTS: Following oral administration of 1 alpha-OHD3, a decrease in serum alkaline phosphatase was seen when levels at 1 and 6 h were compared to baseline (P < 0.05). Oral and i.v. drug administrations resulted in an increasing trend in serum Ca2+ throughout the study (P < 0.05). Moreover, a difference in serum Ca2+ was found when 24-h levels after oral 1 alpha-OHD3 dose was compared to baseline (P < 0.05). Serum osteocalcin at 12 and 24 h after oral 1 alpha-OHD3 compared to baseline were increased (P < 0.05). Intact PTH followed a circadian rhythm after all three routes of drug delivery. After 24 h, significant decreases of intact PTH were observed in the oral and i.v. group. No changes in serum phosphate and serum PICP levels were observed over time after oral, i.p., and i.v. delivery of 1 alpha-OHD3. However, serum PIIINP following oral and i.p. administration of 1 alpha-OHD3 decreased at 1 and 6 h (P < 0.05). CONCLUSION: Oral and i.v. administration of 1 alpha-OHD3 does influence serum levels of osteocalcin, PTH, and PIIINP: Noticeable is the significant increase in serum osteocalcin after oral administration of 1 alpha-OHD3, the remarkable increase (22.6%) in osteocalcin 24 h after i.v. 1 alpha-OHD3, though not statistically significant, the increase in serum PTH levels 12 h following oral and i.v. doses of 1 alpha-OHD3 and the moderate effect on serum Ca2+ levels.

Administration, Oral↗
PubMed1994

Transperitoneal transport of creatinine. A comparison of kinetic models.

Six kinetic models of transperitoneal creatinine transport were formulated and validated on the basis of experimental results obtained from 23 non-diabetic patients undergoing peritoneal dialysis. The models were designed to elucidate the presence or absence of diffusive, non-lymphatic convective and lymphatic convective solute transport. The validation procedure included an assessment of theoretical (a priori) and practical (a posteriori) identifiability, goodness of fit, residual error analysis and plausibility of parameter estimates. The results of the validation procedure demonstrate that the model including all three forms of transport is superior to other models. We conclude that the best model of transperitoneal creatinine transport includes diffusion, non-lymphatic convective transport and lymphatic convective transport.

Adult↗