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PubMed2001

Changes in heart rate variability in chronic uremic patients during ultrafiltration and hemodialysis.

BACKGROUND: The analysis of heart rate variability (HRV) is a useful tool to evaluate cardiac autonomic modulation, which is frequently impaired in chronic uremia. AIMS: The aim of this study was to evaluate HRV in chronic uremics and to separately investigate the acute changes induced by volume depletion and solute removal during a hemodialysis session. METHODS: Fourteen uremic patients (8 males and 6 females, aged 50 +/- 15 years) on maintenance hemodialysis and 14 sex- and age-matched healthy controls were studied. Both groups underwent ambulatory electrocardiogram monitoring to evaluate the HRV time and frequency domain indices. The hemodialysis session was performed by 1 h of high-rate isolated ultrafiltration followed by 3 h of bicarbonate diffusive procedure. RESULTS: In uremic patients, the overall variability in the frequency [low-frequency power (LF): 505 +/- 473, vs. 1,446 +/- 654; high-frequency power (HF): 133 +/- 162 vs. 512 +/- 417; p < 0.001] and time domain indices (standard deviation of normal R-R intervals: 101.9 +/- 33.3 vs. 181.7 +/- 44.1 ms; p < 0.001) was markedly reduced compared to controls, whereas mean heart rate (83 +/- 12.4 vs. 60.9 +/- 8.8 bpm; p < 0.001) and LF/HF ratio (5.8 +/- 3.5 vs. 2.2 +/- 0.8; p < 0.001) were increased. Isolated ultrafiltration produced a marked further decrease in HRV indices, but the subsequent diffusive hemodialysis procedure, with a low ultrafiltration rate, made HRV increase again. CONCLUSIONS: Chronic uremics showed abnormal autonomic modulation with sympathetic-vagal imbalance. The unbalanced hypersympathetic response to body fluid depletion is related to the ultrafiltration rate. Low interdialytic weight gain and a low ultrafiltration rate, associated with adequate hemodialysis, should be the preferable strategy for uremic patients with autonomic dysfunction.

Adult↗
PubMed2006

Peritoneal ultrafiltration: mechanisms and measures.

The net ultrafiltration during peritoneal dialysis equals the osmotic ultrafiltration minus the fluid loss. Fluid loss is made up primarily of hydrostatic pressure-driven convection to the tissues surrounding the peritoneal cavity and a lesser amount of lymph flow. The cellular and blood capillary sources of water are distributed in an interstitial matrix, which decreases the effective osmotic pressure in the vicinity of the microvasculature. The interstitial matrix makes the process of fluid removal far less efficient than it would be if the blood capillaries were actually in direct contact with the peritoneal fluid. Osmotically driven water transport occurs chiefly across the blood capillary endothelium into the interstitium and ultimately out into the peritoneal cavity. Aquaporin-1, water-only channels, are important for solute-free water transport from blood capillaries. There may also be specialized water channels in cells, but this likely provides only a small component of solute-free water to the peritoneal cavity. Signs of ultrafiltration failure include loss of solute-free ultrafiltration and general decrease in ultrafiltration below 400 ml with a 4-h dwell of hypertonic dialysate.

Humans↗
PubMed1988

Cardiovascular function and arterial blood gases during isolated ultrafiltration in healthy man.

In order to recognize possible cardiovascular signs of underhydration during isolated ultrafiltration (IUF), we have studied the physiological hemodynamic adaptation to IUF in healthy man both above and below normohydration. In 7 subjects IUF was performed with the subjects in a normohydrated state at the start of IUF. In 8 subjects the IUF was preceded by a 1-hour infusion of Ringer solution equal to 3% of body weight. By invasive techniques, cardiac index (thermodilution), stroke index, heart rate, brachial and pulmonary arterial blood pressures, systemic vascular resistance index, central blood temperature, PaO2 and PaCO2 were measured. Calf vascular resistance was assessed by venous occlusion plethysmography. A recirculation period of 30 min was followed by IUF in both study groups. During IUF with overhydration and normohydration at the start of IUF, cardiac output fell because of a decline in stroke volume and an unchanged heart rate. Blood pressure remained constant because of systemic vascular constriction. PaO2 and PaCO2 remained unchanged. IUF in healthy man is mainly characterized by vascular constriction and an unchanged heart rate. Thus, the cardiovascular adaptation to ultrafiltration was the same whether or not ultrafiltration was performed at overhydration or normohydration at the start of ultrafiltration. Therefore, it is unlikely that monitoring of heart rate or noninvasive recording of blood pressure can predict whether a subject is becoming underhydrated during isolated ultrafiltration. The adaptation to IUF is similar to that observed during the treatment of uremic patients without complications.

Blood Gas Analysis↗
PubMed2006

Impact of modified ultrafiltration on morbidity after pediatric cardiac surgery.

Cardiopulmonary bypass is a double-edged sword. Without it, corrective cardiac surgery would not be possible in the majority of children with congenital heart disease. However, much of the perioperative morbidity that occurs after cardiac surgery can be attributed to a large extent to pathophysiologic processes engendered by extracorporeal circulation. One of the challenges that has confronted pediatric cardiac surgeons has been to minimize the consequences of cardiopulmonary bypass. Ultrafiltration is a strategy that has been used for many years in an effort to attenuate the effects of hemodilution that occur when small children undergo surgery with cardiopulmonary bypass. Over the past several years, a modified technique of ultrafiltration, commonly known as modified ultrafiltration, has been used with increasing enthusiasm. Multiple studies have been undertaken to assess the effects of modified ultrafiltration on organ function and postoperative morbidity following repair of congenital heart defects. This review attempts to evaluate current available scientific evidence on the impact of modified ultrafiltration on organ function and morbidity after pediatric cardiac surgery.

Cardiac Surgical Procedures↗
PubMed1993

Cytokines in plasma and ultrafiltrate during continuous arteriovenous haemofiltration.

Cytokines are considered to be important mediators in the pathophysiology of sepsis and septic shock. We investigated if continuous arteriovenous haemofiltration (CAVH) could be used to remove excessive amounts of the cytokines tumour necrosis factor-alpha (TNF alpha), interleukin (IL)-1 alpha and IL-6 from peripheral blood in critically ill patients. Nine septic patients with renal failure were treated with CAVH. Ultrafiltrate and plasma were tested for cytokines by ELISA. All patients had detectable TNF alpha and IL-6 plasma levels, ranging from 10-750 pg/ml and 50-4,575 pg/ml, respectively. TNF alpha was removed by the ultrafiltrate with concentrations ranging from 10-1,000 pg/ml. The TNF alpha levels were significantly higher in the ultrafiltrate samples than in the corresponding plasma samples (P < 0.003). IL-6 was undetectable in the ultrafiltrate from five of the patients despite concomitant high plasma levels. IL-1 alpha was detectable in both plasma and ultrafiltrate in four patients. All patients developed multi-organ failure and septic shock and seven died. It is concluded that TNF alpha and IL-1 alpha but not IL-6 can be removed by CAVH in patients with sepsis.

Acute Kidney Injury↗
PubMed2002

Prooxidant and antioxidant properties of human serum ultrafiltrates toward LDL: important role of uric acid.

Oxidized LDL is present within atherosclerotic lesions, demonstrating a failure of antioxidant protection. A normal human serum ultrafiltrate of Mr below 500 was prepared as a model for the low Mr components of interstitial fluid, and its effects on LDL oxidation were investigated. The ultrafiltrate (0.3%, v/v) was a potent antioxidant for native LDL, but was a strong prooxidant for mildly oxidized LDL when copper, but not a water-soluble azo initiator, was used to oxidize LDL. Adding a lipid hydroperoxide to native LDL induced the antioxidant to prooxidant switch of the ultrafiltrate. Uric acid was identified, using uricase and add-back experiments, as both the major antioxidant and prooxidant within the ultrafiltrate for LDL. The ultrafiltrate or uric acid rapidly reduced Cu2+ to Cu+. The reduction of Cu2+ to Cu+ may help to explain both the antioxidant and prooxidant effects observed. The decreased concentration of Cu2+ would inhibit tocopherol-mediated peroxidation in native LDL, and the generation of Cu+ would promote the rapid breakdown of lipid hydroperoxides in mildly oxidized LDL into lipid radicals. The net effect of the low Mr serum components would therefore depend on the preexisting levels of lipid hydroperoxides in LDL. These findings may help to explain why LDL oxidation occurs in atherosclerotic lesions in the presence of compounds that are usually considered to be antioxidants.

Amidines↗
PubMed1984

The EMIT FreeLevel ultrafiltration technique compared with equilibrium dialysis and ultracentrifugation to determine protein binding of phenytoin.

A rapid new ultrafiltration technique (EMIT FreeLevel System I) for the routine measurement of unbound phenytoin concentrations was evaluated. The precision of this procedure was sufficient (between-days coefficient of variation, 11.7%). The results obtained by the ultrafiltration technique for the percentage of free phenytoin in samples from about 40 non-uraemic patients treated with this drug were in good agreement with those determined by ultracentrifugation and equilibrium dialysis (ultrafiltration vs ultracentrifugation, y = 0.94x + 0.60%; ultrafiltration vs equilibrium dialysis, y = 1.02x - 0.60%). The mean value of the results obtained by ultracentrifugation was significantly about 8% lower than that observed with equilibrium dialysis, apparently due to a sedimentation of free phenytoin during ultracentrifugation. With the methods used in our study, the mean values of percentage phenytoin bound to serum proteins obtained in samples from non-uraemic patients ranged from 91.8 to 92.8%. All 3 methods yielded similar binding curves for phenytoin, with spiked human pool sera containing albumin concentrations between 19 and 45 g/L. A rise of the unbound phenytoin fraction was observed with increasing total concentrations of the drug and a decrease of the albumin concentration. With samples from non-uraemic patients (n = 203), a rather good correlation was found between free and total phenytoin concentrations (r = 0.91). In a number of patients (n = 11), free phenytoin concentrations correlated better than total phenytoin concentrations with the clinical status. Patients with free phenytoin concentrations of less than or equal to 2.1 micrograms/ml and total phenytoin concentrations above the therapeutic range did not show signs of toxicity. From the results of our study it is concluded that the EMIT FreeLevel ultrafiltration technique is very well-suited for a rapid and reliable separation of unbound phenytoin. In patients with altered protein binding or an unusual clinical response, free phenytoin determinations appear to be necessary for proper interpretation of total phenytoin levels and rational dosage adjustment.

Adolescent↗
PubMed2002

Screening drugs for metabolic stability using pulsed ultrafiltration mass spectrometry.

A pulsed ultrafiltration-mass spectrometric screening method has been developed to evaluate the metabolic stability of drugs. Pooled human liver microsomes containing cytochrome P450 enzymes were trapped by an ultrafiltration membrane in a stirred flow-through chamber, and eight beta-blocker drugs including acebutolol, alprenolol, atenolol, metoprolol, oxprenolol, pindolol, propranolol, and timolol were flow-injected through the chamber along with the cofactor NADPH. The ultrafiltrate was collected, concentrated and analyzed by using liquid chromatography-tandem mass spectrometry (LC-MS-MS) in order to quantitate the unmetabolized fraction of each drug. The metabolic stability of each beta-blocker was determined based on the difference between the corresponding LC-MS-MS peak areas of an experimental incubation and a control without NADPH. A flow-through incubation method, pulsed ultrafiltration metabolic screening minimizes the potential for product feed back inhibition of cytochrome P450 enzymes. The importance of this phenomenon was illustrated by the observation that the metabolic stability of the set of beta-blocker drugs measured using pulsed ultrafiltration more closely resembled the in vivo stability than that determined using a conventional batch incubation with microsomes or an incubation with human hepatocytes. Since a mixture of compounds was analyzed, the relative metabolic stability of each compound could be assessed by comparison to the other compounds in the incubation. This approach might be particularly useful for the ranking of a directed library of drug leads with respect to metabolic stability and then the selection of lead compounds for further drug development.

Adrenergic beta-Antagonists↗
PubMed1978

[Hydrolyzed lactose contained in the ultrafiltrate of milk or milk products in an enzymatic membrane reactor].

Milk and milk by-products with a low lactose content, very interesting from a nutritional and technological point of view, were obtained by the application of the enzymatic membrane reactor technique. A previous separation of the aqueous phase of milk or ultrafiltrate was necessary and realized by ultrafiltration. The enzyme, a commercial beta-galactosidase, was maintained in solution in the retentate part of the membrane reactor. The optimal conditions of the lactose hydrolysis in milk and whey ultrafiltrates were determined. The behaviour of the aqueous phase of milk in membrane reactor, specially of mineral salts, was studied. Three possibilities were proposed to avoid a calcium-phosphate deposit on the surface of (and in) the reactor membranes: a precipitation of calcium salts by heating, a partial demineralization by electrodialysis or ion exchange, a calcium complexation by addition of sodium citrate. A continuous process for the lactose hydrolysis of milk and demineralized whey or milk ultrafiltrate was proposed. The organoleptic quality of low lactose milk, before and after heat treatment, was evaluated by a tasting panel. High sweeting syrup, were obtained by concentration of lactose hydrolyzed and demineralized ultrafiltrates. Nutritional aspects of these products are discussed specially from the toxicological point of view of galactose.

Animals↗
PubMed1999

New methods of protein purification. Affinity ultrafiltration.

This review describes a recently developed method for protein purification-affinity ultrafiltration. In affinity ultrafiltration, the protein to be purified is complexed with a macroligand composed of a soluble polymer or an insoluble microparticle with covalently bound, target protein-specific affinity ligands. The complex is trapped by an ultrafiltration membrane, whereas unwanted proteins pass through the membrane. The unwanted proteins are removed from the system by the carrier liquid. The system is then supplemented with an agent eluting the target protein by dissociating it from the microligand complex. The purified protein then passes the membrane, while the macroligand is trapped by it. The macroligand can be re-used after regeneration. Affinity ultrafiltration has a number of advantages over other protein purification techniques: 1) commercial availability of ultrafiltration systems with various high-productivity designs; 2) availability of presynthesized macroligands, which can be supplemented with additional, easily manufactured, commercial latex-based macroligands; 3) rapid separation of large solution volumes; 4) repeated use of equipment, enabling consecutive purification of different proteins; 5) simple scale-up and automation procedures.

Ligands↗
PubMed2001

An experimental evaluation of continuous cardiotomy reservoir ultrafiltration.

Ultrafiltration has been suggested as a means to reduce the morbidity associated with blood activation. However, the application of ultrafiltration to the highly activated blood of the cardiotomy suction subcircuit has not been investigated. The purpose of this study was to determine whether cardiotomy reservoir ultrafiltration (CRUF) would be effective in altering cytokine levels. Six swine, undergoing 90 min of cardiopulmonary bypass (CPB), were divided into two groups; one group was assigned to receive CRUF (N = 3), the other was to serve as controls and did not receive ultrafiltration (N = 3). Blood samples were analyzed for hematocrit, plasma-free hemoglobin, total protein, interleukin-8 (IL-8), and tumor necrosis factor alpha (TNF-alpha). Samples were taken pre-bypass, postheparinization, every 30 min during CPB, post-CPB and postprotamine. All data were analyzed using a one-way analysis of variance (ANOVA), with significance accepted at p < .05. There were no significant differences found between treatment and control groups for plasma-free hemoglobin levels (22.4 +/- 22.2 vs. 14.6 +/- 14.4; 40.1 +/- 26.1 vs. 40.0 +/- 19.3). After 90 min of ultrafiltration, there was a significant decrease in TNF-alpha (261.6 +/- 119.6 vs. 71.8 +/- 11.4; p = .02). Although IL-8 levels decreased from throughout the experiment, concentrations did not reach statistical significance. In conclusion, CRUF can be used without increasing cellular destruction, and can decrease certain cytokine levels. Our results suggest that further clinical studies should be undertaken utilizing this technique with a larger sample size.

Analysis of Variance↗
PubMed2001

New parameter for monitoring fouling during ultrafiltration of WWTP effluent.

Variations in water quality of waste water treatment plant (WWTP) effluent complicate ultrafiltration of this feed water. Traditional parameters do not provide sufficient information to explain the fouling of membranes during ultrafiltration of WWTP effluent. New parameters for measuring and monitoring the fouling potential of feed water for ultrafiltration membranes need to be developed. The normalised membrane fouling index for ultrafiltration membranes (MFI-UFn) can be used as such and is according to the cake filtration theory calculated from the ratio of filtration time and filtration volume as a function of the filtration volume. MFI-UFn can be calculated from both experiments with constant Trans Membrane Pressure (TMP) and from experiments with constant flux. This parameter can also be calculated independent of the scale of the experiment. Results show that differences in fouling potential can be measured for various feed waters using the same membrane type and for various membrane types using the same feed water. Variation in feed water quality leads to a deviation of the MFI-UFn, as was found especially for WWTP effluent. The applied TMP influences the value of the MFI-UFn, indicating cake compression when applying a higher TMP. MFI-UFn can be used to identify the effect of pre-treatment methods, which is useful when using WWTP effluent as feed water for an ultrafiltration processes.

Equipment Contamination↗
PubMed2001

Effects of ultrafiltration on enoxaparin: an in vitro analysis.

The use of low molecular weight heparins (LMWH) as an anticoagulant in the heparin-resistant patient poses challenges during cardiopulmonary bypass (CPB). The ultrafiltrability of LMWH has not been previously examined. The purpose of this study was to determine the effects of continuous ultrafiltration on the concentraton of a LMWH, enoxaparin. An in vitro analysis was performed using fresh whole human blood and an extracorporeal circuit containing four parallel ultrafiltrators and a cardiotomy reservoir with an integrated heat exchanger. Constant conditions included temperature (37 degrees C), flow (0.20 L-min(-1)) transmembrane pressure (200 mmHg), and hematocrit (25 +/- 2%). Samples were collected at the inlet, outlet, and ultrafiltrate line at one and three min for one control trial and again for each of the four hemoconcentrators following the bolus of enoxaparin. Coagulation measurements included a viscoelastic monitor (TEG), activated clotting time (ACT), activated partial thromboplastin time (aPTT), and quantitative analysis utilizing a membrane-based electrode for potentiometric measurement of polyanionic concentrations of enoxaparin. Enoxaparin concentration, from inlet to outlet, increased from 2.95 +/- 0.64 to 5.89 +/- 0.95 (p < .001) at 1 min and 4.24 +/- 0.49 to 7.89 +/- 0.606 (p < .001) at 3 min. Kinetic clot activity, as assessed by the TEG index, decreased from -3.8 +/- 2.5 vs. -10.5 +/- 6.0; (p < .01) pre- to postultrafiltrator samples after 3 min. ACT and aPTT results demonstrated no significant change. In conclusion, this study demonstrates enoxaparin is concentrated with the use of continuous ultrafiltration. Functional coagulation studies also indicate a concentrating effect, primarily via the TEG.

Anticoagulants↗
PubMed2003

Validation of ultrafiltration as a method of measuring free 99mTc-MDP.

UNLABELLED: Quantitative studies of the kinetics of (99m)Tc-methylene diphosphonate ((99m)Tc-MDP) in metastatic and metabolic bone disease require the measurement of free tracer in plasma to derive the input function. Several methods of measuring free (99m)Tc-MDP have been described including ultrafiltration, precipitation using trichloroacetic acid, and a direct in vivo measurement based on the assumption that free MDP is cleared through the kidneys by glomerular filtration. The aim of this study was to validate ultrafiltration as a convenient and accurate method of measuring the free fraction of (99m)Tc-MDP by comparing it with the glomerular filtration rate (GFR) method. A second aim was to measure the percentage of free (99m)Tc-MDP in a cross-section of patients using ultrafiltration to determine the interpatient variability and, therefore, whether individual measurements are required for bone kinetic studies. METHODS: In study 1, 10 volunteers (7 women, 3 men; mean age, 37 y; range, 26-55 y) were injected with 3 MBq (99m)Tc-MDP and 3 MBq (51)Cr-ethylenediaminetetraacetic acid, and multiple blood and urine samples were taken between 0 and 4 h. Plasma samples were spun in 5-, 10-, and 30-kDa filters and counted in a gamma-counter. In study 2, 51 randomly selected patients (26 women, 25 men; mean age, 66 y; range, 31-87 y) attending our department for a routine bone scan were injected with 600 MBq (99m)Tc-MDP, and 4 blood samples were taken between 0 and 4 h and spun in 10-kDa filters. RESULTS: In study 1, the mean percentages (+/-SD) of free (99m)Tc-MDP at 5 min and 4 h after injection measured using the 10-kDa filters were 83.1% +/- 3.4% and 44.0% +/- 10.0%. The mean ratios (+/-SEM) of the free (99m)Tc-MDP in ultrafiltrate compared with the GFR method for the 5-, 10-, and 30-kDa filters were 0.894 +/- 0.010, 0.943 +/- 0.009, and 0.987 +/- 0.010. In study 2, the mean percentages (+/-SD) of free (99m)Tc-MDP at 15 min and 4 h were 75.3% +/- 8.0% and 48.8% +/- 9.5%, with a precision error of 2.3%. The percentages of free MDP at 150 min and 4 h were significantly correlated with GFR but not with serum albumin. CONCLUSION: Ultrafiltration provides an accurate method of evaluating free (99m)Tc-MDP in plasma for bone kinetic studies. The results from both the healthy volunteers in study 1 and the patients in study 2 show that protein binding varied with time and showed significant differences between individuals that were partly dependent on GFR. It is thus necessary to measure individual protein binding values for bone kinetic studies.

Adult↗
PubMedDate not supplied

Enhanced ultrafiltration using 7.5% icodextrin/1.36% glucose combination dialysate: a pilot study.

OBJECTIVE: A pilot study to compare the use of a combination dialysate (7.5% icodextrin/1.36% glucose) versus icodextrin 7.5% alone for the long dwell in patients on peritoneal dialysis (PD). DESIGN: A 4-week, prospective, randomized crossover study. SETTING: A large regional renal unit providing treatment for a population of 1.7 million. PATIENTS: Five patients on continuous ambulatory PD (CAPD) and 3 patients on automated PD. MAIN OUTCOME MEASUREMENTS: Long-dwell and 24-hour ultrafiltration volumes, body weight, 24-hour ambulatory blood pressure, and antihypertensive/diuretic tablet count. RESULTS: The use of the combination dialysate resulted in an increase in the median (interquartile range) long-dwell ultrafiltration, from 750 (650-828) mL to 1000 (889-1100) mL (p < 0.001), and 24-hour ultrafiltration, from 739 (400-1623) mL to 956 (700-1750) mL (p < 0.001). Weight, blood pressure, and tablet count remained unchanged. CONCLUSIONS: The use of the novel combination dialysate resulted in a 33% increase in long-dwell ultrafiltration and a 29% increase in 24-hour ultrafiltration.

Adult↗
PubMed1991

[Ultrafiltration as a fast and simple method for determination of free and protein bound prilocaine concentration. Clinical study following high-dose plexus anesthesia].

Ultrafiltration as a Fast and Simple Method to Separate Free and Protein Bound Concentrations of Local Anesthetics/Pharmacokinetic studies following high-dose anesthesia of the axillary plexus. As many other drugs amide-type local anesthetics are protein bound in plasma. The extent of binding varies between local anesthetics. The free, non protein-bound fraction of these drugs is mainly responsible for cardiovascular and central-nervous side effects. If high doses are necessary for regional anesthetic procedures it seems reasonable to determine the pharmacological active, non protein-bound fraction in addition to the total concentration of the local anesthetic drug. Analyses of protein binding was performed using an ultrafiltration method which is discussed in this paper. Total (HPLC) and unbound plasma levels (combination of ultrafiltration and HPLC) of the local anesthetic drug in central venous blood were studied in 20 healthy orthopedic patients, undergoing plastic surgery of the upper limb (elbow, forearm, hand), over a time period of 90 min, when performing axillary plexus block with 30 ml prilocaine (CAS 721-50-6) 2% (= 600 mg). Separation of the local anesthetic fractions was achieved using the ultrafiltration system MPS-1, equipped with a YMT-membrane. These membranes have a narrow pore size retaining molecules larger than 30000 Dalton. Ultrafiltration was accomplished by subjecting 1.2 ml of plasma to centrifugation at 2000 x g for 60 min at 30 degrees C using a clinical centrifuge equipped with a 35 degree angle head rotor. The plasma samples were adjusted to physiological pH (7.40) with a sodium-potassium-phosphate buffer. The tightness of the used membrane was controlled by a micromethod for protein estimation (sensitivity 10 micrograms/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Proteins↗
PubMed1990

Determination of free progesterone in an ultrafiltrate of saliva collected in situ.

We have investigated the utility of an ultrafiltrate of saliva for measuring progesterone as an indicator of luteal function during the menstrual cycle of women. A filtrate of saliva is collected in the mouth by means of an osmotic pump that accumulates medium containing only molecules less than 12,000 Da. We analyzed the nonextracted ultrafiltrate by a solid-phase immunoassay for progesterone and monitored the mid-luteal surge of lutropin in urine with a liquid-phase radioimmunoassay. Progesterone concentrations in the ultrafiltrate are significantly lower during the follicular phase and increase after the release of lutropin. The concentration of progesterone in the ultrafiltrate correlates closely with total progesterone in matched blood samples (r = 0.84, cycle 1; and r = 0.89, cycle 2). Likewise, we found a good correlation between the results in whole saliva and in the ultrafiltrate (r = 0.95). The described method of obtaining a pre-processed specimen noninvasively simplifies the self-collection of samples by patients (including collection at home); excludes potential interference from microorganisms, desquamated cells, and salivary components; and simplifies the processing of the biological fluid in the laboratory.

Adult↗
PubMed1989

Phosphatidylcholine administration in continuous ambulatory peritoneal dialysis (CAPD) patients with reduced ultrafiltration.

To evaluate the possible role of oral phosphatidylcholine administration in improving peritoneal ultrafiltration sixteen continuous ambulatory peritoneal dialysis (CAPD) patients with a reduced ultrafiltration rate (less than 500 mL/4 h after a standard 3.86% glucose exchange) were studied. Three patients spontaneously stopped phosphatidylcholine due to gastric side effects. Three out of the remaining 13 patients showed a mild increase of standard ultrafiltration, which was not followed by any increase in daily dialysate output. No differences in glucose, sodium, potassium, urea and creatinine equilibration curves were seen. In conclusion, in our series oral phosphatidylcholine is not free of side effects, and its efficacy in improving ultrafiltration is scanty, with no clinical relevance in increasing daily ultrafiltration.

Administration, Oral↗