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PubMed2006

Thermodynamic stability of fluid-fluid phase separation in binary athermal mixtures: the role of nonadditivity.

We studied the thermodynamic stability of fluid-fluid phase separation in binary nonadditive mixtures of hard-spheres for moderate size ratios. We are interested in elucidating the role played by small amounts of nonadditivity in determining the stability of fluid-fluid phase separation with respect to the fluid-solid phase transition. The demixing curves are built in the framework of the modified-hypernetted chain and of the Rogers-Young integral equation theories through the calculation of the Gibbs free energy. We also evaluated fluid-fluid phase equilibria within a first-order thermodynamic perturbation theory applied to an effective one-component potential obtained by integrating out the degrees of freedom of the small spheres. A qualitative agreement emerges between the two different approaches. We also addressed the determination of the freezing line by applying the first-order thermodynamic perturbation theory to the effective interaction between large spheres. Our results suggest that for intermediate size ratios a modest amount of nonadditivity, smaller than earlier thought, can be sufficient to drive the fluid-fluid critical point into the thermodinamically stable region of the phase diagram. These findings could be significant for rare-gas mixtures in extreme pressure and temperature conditions, where nonadditivity is expected to be rather small.

Journal Article↗
PubMed2006

Pulmonary endothelial permeability is increased by fluid from packed red blood cell units but not by fluid from clinically-available washed units.

BACKGROUND: Massive transfusions are a risk factor for acute respiratory distress syndrome (ARDS) in severely injured patients. Neutrophil priming has been proposed to be an integral part of the early inflammatory response to trauma. To complement that work, we studied another major cell type involved in inflammation: the endothelial cell. Our hypothesis was that soluble factors from units of leukoreduced packed red blood cells (PRBC) directly increase pulmonary endothelial permeability. We also determined whether fluid from clinically-available washed PRBC units affects endothelial permeability. METHODS: As a measure of permeability, transendothelial electrical resistance (TER) was determined across monolayers of a human pulmonary microvascular endothelial cell line after addition of full-strength, diluted, and washed PRBC fluid. Monolayers were stained with phalloidin to assess intercellular space. Storage solution Adsol-1 was tested alone to determine additive component effects on TER. RESULTS: PRBC fluid decreased TER and increased intercellular space, both of which indicate an increase in endothelial monolayer permeability. PRBC fluid diluted to 2% and washed PRBC fluid did not decrease TER and thereby did not change endothelial permeability. Likewise, Adsol-1 did not duplicate the dramatic decrease in TER seen with the PRBC fluid. CONCLUSIONS: Fluid from stored PRBC units contains a soluble, transferable factor that directly increases endothelial permeability. Fluid from washed PRBC units, currently available for patients with immunoglobulin A allergies, does not. This study complements previous work of others that demonstrated that neutrophil priming by PRBC fluid is abrogated by washing. Now that two cell types have been shown to respond more favorably to washed PRBC in vitro, clinical studies should be initiated to investigate whether use of washed PRBC reduces ARDS following transfusions in trauma patients.

Capillary Permeability↗
PubMed1991

Pharmacist interventions improve fluid balance in fluid-restricted patients requiring parenteral nutrition.

Many intensive care unit (ICU) patients require parenteral nutrition (PN) and fluid restriction, making delivery of adequate nutrition difficult. We studied the effects of pharmacist interventions on fluid balance in fluid-restricted ICU patients requiring PN. Twenty patients were randomized to the treatment group (dextrose 70% injection [D70W] plus 15% amino acids for PN, 25-mL piggybacks, selected drugs added to the PN solution) or the control group (D70W plus 10% amino acids, 50- or 100-mL piggybacks). Each group contained 10 patients and they were not significantly different for age, gender, weight, hospital days, and serum albumin concentration. The duration (9.3 +/- 1.2 vs. 9.7 +/- 2.4 d) and doses of PN (29 +/- 6.8 vs. 28.7 +/- 6.9 kcal/kg/d; 1.1 +/- 0.3 vs. 1.1 +/- 0.4 g/kg/d protein) were similar between treatment and control groups. Mean fluid intake (3112 +/- 1146 vs. 3498 +/- 1111 mL/d), fluid balance (146 +/- 1581 vs. 708 +/- 1402 mL/d), and cumulative fluid balance (1358 vs. 6867 mL) were all significantly lower in the treatment group. Mean fluid output was similar between the two groups. Pharmacist interventions can significantly decrease intake and result in a better fluid balance in fluid-restricted ICU patients who require PN.

Adult↗
PubMed1991

Fluid balance during pulmonary edema. Is fluid gain a marker or a cause of poor outcome?

STUDY OBJECTIVE: To evaluate the importance of fluid balance and changes in extravascular lung water (EVLW) on survival in the ICU and short-term outcome in patients with pulmonary edema. DESIGN: Retrospective analysis of data (sorting by survival and "treatment received") from a recent randomized controlled trial of fluid restriction in this population. SETTING: Medical ICU of a university-affiliated, tertiary-care medical center. PATIENTS: Eighty-nine patients (from the previously mentioned study) requiring pulmonary artery catheterization with abnormally high EVLW (greater than 7 ml/kg). MEASUREMENTS AND RESULTS: When analyzed by survival, the survivors had no significant fluid gain or change in EVLW but decreased wedge pressure and body weight, compared to nonsurvivors. When analyzed by fluid balance, patients who gained less than 1 L of fluid by 36 hours into the study had a better rate of survival (74 percent) than the rest (50 percent; p less than 0.05). Also, the median duration of days on the ventilator, ICU days, and days of hospitalization was approximately half as long for each variable in the group with less than 1 L of fluid gain. Even accounting for baseline differences in the severity of illness, fluid balance was an independent predictor of survival (p less than 0.05). When analyzed by whether or not EVLW decreased by more than 15 percent between the first and last measurement, only patients with ARDS or sepsis had decreased days on the ventilator and ICU days. CONCLUSIONS: These data support the concept that positive fluid balance per se is at least partially responsible for poor outcome in patients with pulmonary edema and defend the strategy of attempting to achieve a negative fluid balance if tolerated hemodynamically.

Extravascular Lung Water↗
PubMed1993

Fluid flow during percutaneous drainage procedures: an in vitro study of the effects of fluid viscosity, catheter size, and adjunctive urokinase.

OBJECTIVE: An in vitro study was performed to determine the range of flow times of different bodily fluids through catheters of different diameters and to test the hypothesis that urokinase might decrease the viscosity of purulent material. MATERIALS AND METHODS: A standard viscometer was used to measure the viscosities of water, blood, pseudocyst fluid, purulent material, and purulent material with admixed urokinase. For each fluid, Poiseuille's law was used to calculate the kinematic viscosity, from which theoretical drainage times through seven different sizes of catheters were calculated. These theoretical times were compared with the actual measured values to verify that flow was according to Poiseuille's law. RESULTS: The calculated kinematic viscosities (in 10(-6) stokes) were as follows: water, 0.695 +/- 0.006; pseudocyst fluid, 2.185 +/- 0.008; blood, 3.001 +/- 0.049; abscess fluid without urokinase, 5.729 +/- 0.064; and abscess fluid with urokinase, 4.416 +/- 0.070. The viscosity of abscess fluid decreased by 23% with the addition of urokinase. Drainage time was considerably shorter with larger catheters. CONCLUSION: Flow of various bodily fluids, including pus, is according to Poiseuille's law, confirming that for more viscous fluid, larger catheters provide more rapid drainage. Urokinase decreases viscosity of purulent material and increases flow for all sizes of catheters.

Abscess↗
PubMed1993

Dynamics of prolactin in amniotic fluid and extraembryonic coelomic fluid in early human pregnancy.

Concentrations of prolactin were measured by an immunoradiometric assay in 26 matched samples of amniotic fluid, extraembryonic coelomic fluid and maternal serum from 9 to 12 weeks of pregnancy and in a further 131 amniotic fluid samples from 9 to 20 weeks. Low levels of prolactin (median 40 MU/l) were present in amniotic fluid from 9 to 12 weeks. Levels in the coelomic fluid were higher (median level 371 MU/l; P < 0.0001) than in amniotic fluid. From 13 weeks, there was a rapid rise in amniotic fluid prolactin to reach a peak at 19 weeks (median level 99,850 MU/l). The pattern of increase of prolactin in amniotic fluid is similar to, but occurs 2 weeks later than that for insulin-like growth factor-binding protein-1, another major decidual product.

Amniotic Fluid↗
PubMed1995

Progesterone concentrations in serum, follicular fluid, and oviductal fluid of the golden hamster during the periovulatory period.

In vitro, progesterone induces capacitation, hyperactivated motility, and acrosome reactions in sperm, possibly acting through a non-genomic plasma membrane receptor, but neither progesterone functions nor concentration within the mammalian oviduct during the periovulatory period is well characterized. The objectives of this study were to determine the physiological concentrations of progesterone in serum, follicular fluid, and oviductal fluid of golden hamsters during the period of the reproductive cycle in which capacitation and fertilization occur. Fluids were collected from different groups of animals for each of four time points: the normal time for mating (5-6 h post-LH surge [post-LH]), early in capacitation (8-9 h post-LH), immediately preovulation (11-12 h post-LH), and after ovulation near the beginning of fertilization (14-15 h post-LH). Oviductal fluid was collected by 1-h cannulation followed by cardiac puncture for serum collection and follicle aspiration for follicular fluid. Within each time period, the three types of fluid differed significantly in progesterone concentration. Over time, concentrations of progesterone did not change in either serum (range: 5.64-12.85 ng/ml) or follicular fluid (range: 4.2-7.4 micrograms/ml), but the concentration of progesterone in oviductal fluid decreased from 175.06 ng/ml at the first period to 44.01 ng/ml at the fourth (p < 0.05), while the volume of oviductal secretions collected by the same sampling procedure increased from 1.6 to 2.9 microliters (p < 0.05). With this information concerning in vivo concentrations of progesterone during capacitation and fertilization, the physiological role of progesterone in sperm-egg interactions can be addressed.

Animals↗
PubMed2006

Cytokine signalling in rat pulp interstitial fluid and transcapillary fluid exchange during lipopolysaccharide-induced acute inflammation.

The dental pulp consists of loose connective tissue encased in rigid dentinal walls. Because of its topography the tissue has low interstitial compliance and limited capacity to expand during fluid volume changes. Due to limitations regarding access to interstitial fluid, basic knowledge on transcapillary fluid transport parameters is lacking for this organ. The scope of this project was dual: first we aimed at establishing a method for isolation of pulp interstitial fluid (IF), and second we applied the method in rats subjected to lipopolysaccharide (LPS)-induced endotoxaemia. The aim was to measure colloid osmotic pressure (COP) and pro-inflammatory cytokines in the pulp IF during acute inflammation. Fluid volumes and pulpal blood flow (PBF) were measured to obtain more information about microcirculatory changes that take place in this pulpitis model. By centrifugation of incisor pulp at 239 g we were able to extract fluid representative for IF. Pulp IF had a relative high control COP (approximately 83% of plasma COP) and was similar to plasma COP 3 h after LPS challenge. The pulp exhibited a high content of IF (0.60 +/- 0.03 ml (g wet weight)(-1)) and a vascular volume of 0.03 +/- 0.01 ml (g w.w.)(-1) No differences were observed in the distribution of fluid volumes after 1.5 and 3 h LPS exposure. PBF and systemic blood pressure dropped significantly after LPS administration. PBF remained low whereas systemic blood pressure was re-established during the 3-h period, implying organ dysfunction. There was a differential pattern of cytokine expression in pulp IF and serum with cytokines such as IL-1alpha, IL-1beta and TNF-alpha locally produced, whereas others such as IFN-gamma and IL-6 were produced systemically and probably spilled over to the pulp IF after LPS exposure. Our findings show that pulp IF can be isolated by centrifugation and that this method is useful when studying fluid balance and extracellular signalling mechanisms in the dental pulp in normal and pathological conditions.

Acute Disease↗
PubMed1976

Interstitial fluid and transcapillary fluid balance in the lung.

Alterations in extravascular lung water content when capillary pressure or plasma colloid osmotic pressure is increased have been evaluated in isolated, continuously weighed, plasma-perfused pairs of rabbit lungs. After modest increases in left atrial pressure, most preparations rapidly reached a new stable weight, and thus a new transcapillary fluid balance, but no significant increase in extravascular lung water content could be detected. In preparations where there was still a steady, slow gain in weight and thus still some transvascular filtration of fluid 15 min after the increase in pressure, a moderate but significant increase in extravascular water could be detected. It is concluded that only very small transvascular shifts of fluid occur in the lungs when capillary pressure changes, as long as this change is kept below the level that causes oedema. This limitation of pressure-induced transvascular shifts of fluid in the lung could be explained by the existence, close to the capillaries, of a small interstitial space containing fluid with a high protein concentration. Alterations in the colloid osmotic pressure exerted by this fluid would then contribute markedly towards continuous readjustment of the transcapillary fluid balance in the lung. Experiments by other workers indicate that alveolar pressure can markedly affect the transcapillary fluid balance of the isolated perfused lung.

Animals↗
PubMed1976

The effects of ventricular fluid osmolality on bulk flow of nascent fluid into the cerebral ventricles of cats.

The effects of ventricular fluid osmolality on the bulk flow of nascent fluid into the cerebral ventricles of anesthetized cats was measured during ventriculocisternal perfusion. This nascent fluid consists of both cerebrospinal fluid (CSF) and fluid which results from an osmotic gradient between ventricular fluid and the blood and/or brain. Perfusions were carried out with both mock CSF and with solutions containing either sucrose, urea, or NaCl. Differences between the normal bulk flow rate of nascent CSF and bulk flow rate measured during perfusion with anisotonic solutions were linearly related to corresponding differences in osmolality of the effluent fluid from the ventricles. The coefficients of somotic flow using sucrose (0.231 mul/min per mOsm) and NaCl (0.224) were similar, and greater than that using urea (0.156). During perfusion with sucrose when effluent osmolality increased by 200 mOsm (63% of normal), bulk flow rate of nascent fluid increased by 50 mul/min (200% of normal). Flow was undetectable when the effluent osmolality was 190 mOsm (decrease of 135 mOsm), although osmotically active particles continued to enter the ventricular system. Intravenous injection of acetazolamide reduced these coefficients to similar values of 0.0963 for NaCl, and 0.0955 for urea. In all experimental conditions no changes were found in cerebral water content. These results suggest that the increased bulk flow which occurs during perfusion with hypertonic solutions originates from the choroid plexus.

Acetazolamide↗
PubMed1990

Clear fluids three hours before surgery do not affect the gastric fluid contents of children.

This prospective, randomized, single-blind study of 121 healthy children aged 2 to 12 yr investigated the effect of clear fluids on gastric contents. Gastric fluid volume and pH were measured immediately following the induction of general anaesthesia and were not significantly affected by the ingestion of unlimited clear fluids up to three hours preoperatively. After a prolonged fast (mean fast 14 hr), gastric fluid volume was 0.39 +/- 0.37 ml.kg-1 and gastric pH was 1.7 +/- 0.4; after unlimited clear fluids (203 +/- 109 ml) up to three hours before surgery gastric fluid volume was 0.34 +/- 0.28 ml.kg-1 and gastric pH was 1.8 +/- 0.7 (mean +/- SD). Gastric fluid volume (ml.kg-1) increased in both the control and study groups as age increased, P less than 0.005. It is concluded that drinking clear fluid up to three hours before scheduled surgery does not have a measurable effect on gastric volume and pH of healthy children of ages 2 to 12 yr.

Body Fluids↗
PubMed1994

Follicular fluid lipoproteins in the mare: evaluation of HDL transfer from plasma to follicular fluid.

Using a density gradient ultracentrifugal procedure, we have separated equine plasma and follicular fluid high-density lipoproteins (HDL). The density distribution of the follicular fluid HDL was clearly displaced towards the highest densities in comparison with that of plasma HDL. Similarly, an analysis of size distributions showed a decrease in follicular fluid HDL diameters (4.2 to 9.2 nm) compared to plasma HDL (5.5 to 9.5 nm). HDL were isolated into three subfractions on the basis of the disposition of the Sudan Black stained bands in the centrifuge tubes. Concentrations of each subfraction were clearly lower in the follicular fluid, and the relative percentages with regard to the plasma equivalents were inversely proportional to the molecular weights (23.8% for HDL-1, 49.9% for HDL-2 and 63.7% for HDL-3). The cholesterol/phospholipid molar ratio and the esterified/free cholesterol molar ratio were clearly increased in the follicular HDL-2 and HDL-3 subfractions. The apolipoprotein distribution in follicular fluid HDL was very close to that in plasma HDL. LCAT activity measured in human as well as equine samples was weaker in follicular fluid compared to plasma in both species (4.0 nmol of free cholesterol esterified per h per ml vs. 24 nmol per h per ml). Theoretical concentrations of follicular fluid HDL were calculated assuming that the HDL particles would be merely a filtration product undergoing no detectable metabolic modifications. Biochemical measurements showed that the lightest particles (HDL-1) were less numerous than suggested by the theoretical calculation. Thus, although follicular fluid HDL appear to be a filtration product of plasma HDL, they undergo metabolic transformations that we suggest may be linked to hormonal synthesis and reverse cholesterol transport.

Animals↗
PubMed1992

Correlation of subjective assessment of amniotic fluid with amniotic fluid index.

We assessed the correlation between abnormal amniotic fluid volumes as defined by the two techniques of (1) subjective evaluation and (2) the amniotic fluid index. Ultrasound evaluation of amniotic fluid volume was conducted on 420 pregnant women with known gestational age greater than twenty weeks but less than 42 weeks. Amniotic fluid was evaluated subjectively and placed into one of three categories: normal, oligohydramnios or polyhydramnios. After fetal biometry was performed, the amniotic fluid volume was assessed semi-quantitatively by the amniotic fluid index technique and assigned to similar categories. We analyzed the data with 2 x 2 contingency tables, using amniotic fluid index as the 'gold standard test'. Our study demonstrates that there was moderate agreement (kappa.5) between both amniotic fluid techniques in the identification of oligohydramnios. However, agreement between the techniques was poor for the identification of polyhydramnios (kappa.16).

Amniotic Fluid↗
PubMed1993

Amniotic fluid volume: fluid dynamics and measurement technique.

Evaluation of amniotic fluid volume is an important aspect of obstetrical ultrasound. Several methods are currently used to describe amniotic fluid volumes. The most common are the subjective assessment of fluid and the semiquantitative methods. The reproducibility of these methods is excellent in experienced hands. Because of the multiple methods used to assess fluid, both oligohydramnios and polyhydramnios have numerous definitions. Regardless of which definition is used, it is clear that both of these entities are associated with a variety of fetal and maternal conditions. Abnormal amniotic fluid volume may be the only or earliest sonographic sign of an obstetrical problem. Therefore, it is important that sonologists are familiar with amniotic fluid volume assessment. Although subjective and semiquantitative techniques may produce similar results, a numerical scale is no substitute for experience and training. One should be able to recognize lesser degrees of fluid abnormality and be able to assess the trend of amniotic fluid volume in serial examinations.

Amniotic Fluid↗
PubMed2002

Comparison, characterization, and identification of proteases and protease inhibitors in epididymal fluids of domestic mammals. Matrix metalloproteinases are major fluid gelatinases.

The testicular and epididymal fluids of ram, boar, and stallion were analyzed by means of one-dimensional and two-dimensional gelatin gel zymography. Five main gelatinolytic bands were revealed in the ram and at least seven were observed in the boar and stallion. These proteolytic bands showed regionalized distribution throughout the organs. The two main proteolytic activities at around 54-66 kDa retrieved in all three species were inhibited by EDTA and phenanthroline, indicating that they were metallo-dependent enzymes. The activity of some of the low-molecular-weight gelatinases was also decreased by EDTA, whereas others were inhibited by serine protease inhibitors. One of the main proteases at 60-62 kDa from the caput fluid of the stallion and the ram was N-terminal sequenced; in both cases, high sequence homology was found with the N-terminal of the matrix-metalloproteinase-2 pro-form (pro-MMP-2). Antibodies against MMP-2, MMP-3, and MMP-9 gelatinases confirmed the regional distribution in the fluids of pre -, pro-, active, or degraded forms of these metalloproteases in all three species. We also observed the presence of acrosin in epididymal fluids, which was probably released by dead spermatozoa, but this enzyme did not explain all the serine protease activity. Moreover, the majority of this enzyme is bound to the protease inhibitor alpha(2)-macroglobulin, which is present in the fluids of all three species. TIMP-2, a potent inhibitor of MMPs, was present in the fluid of the caput regions in the ram and boar, and in the caput and caudal fluids of the stallion. This study demonstrated that similar types of proteases and inhibitors are regionally distributed in the epididymal fluids of three domestic species, suggesting an identical role in the sperm maturation process, the plasticity of this organ, or both.

Acrosin↗
PubMed1989

Concentrations of sulphadimidine, oxytetracycline and penicillin G in serum, synovial fluid and tissue cage fluid after parenteral administration to calves.

Drug concentrations in serum, synovial fluid and tissue cage fluid (TCF) in calves were measured after single i.m. doses of oxytetracycline hydrochloride (OTC), procaine penicillin G (PPG) and potassium penicillin G (KPG) and single i.v. doses of sulphadimidine (SDM) and OTC. For all drugs, concentration-time curves in serum and synovial fluid were not identical but they had similar profiles, with peak levels occurring at about the same time. Concurrent concentrations were lower in synovial fluid than in serum. For each drug, elimination half-lives from synovial fluid and from serum were similar, except for penicillin G after KPG administration which had a significantly longer half-life from synovial fluid than from serum (P less than 0.05). Of the two penicillin G preparations, PPG gave a significantly higher synovial fluid:serum area under curve (AUC) ratio than did KPG; 0.76 +/- 0.10 and 0.54 +/- 0.12, respectively (P less than 0.05). For OTC, the synovial fluid:serum AUC-ratio was 0.33 +/- 0.12 after i.m. and 0.34 +/- 0.08 after i.v. administration. Drug concentration-time curves of TCF had different profiles compared with serum, with relatively low and delayed peak levels and slow elimination from TCF. TCF:serum AUC-ratios did not differ significantly for i.m. and i.v. administration of OTC; 0.10 +/- 0.10 and 0.19 +/- 0.03 respectively (P greater than 0.05). Potassium penicillin G (KPG), however, gave a significantly higher TCF:serum AUC-ratio than PPG; 0.55 +/- 0.21 and 0.19 +/- 0.07, respectively (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Enhancement of normal polymorphonuclear cells respiratory burst in ascitic fluid by fibronectin. Comparison between cirrhotic and malignant ascitic fluids.

The chemiluminescence (CL) response of normal peripheral blood polymorphonuclear cells (PMN) in ascitic fluids (cirrhotic = 32; malignant = 17) was studied independently of the ascitic fluid complement activity. CL response and fibronectin levels were higher in malignant ascitic fluid than in cirrhotic ascitic fluid (p less than 0.001). Addition of pure fibronectin or malignant ascitic fluids to cirrhotic ascitic fluids increased the CL response of normal PMN. These findings suggest that the susceptibility of cirrhotic patients to spontaneous bacterial peritonitis (SBP) is a multifactorial defect involving factors distinct from low C3 levels. Fibronectin is an important factor in the promotion of the respiratory burst of normal PMN stimulated by opsonized zymosan or PMA in ascitic fluid. Our results suggest that low levels of ascitic fluid fibronectin could partly explain the high susceptibility of cirrhotic patients to spontaneous bacterial peritonitis.

Adult↗
PubMed1997

Structural and functional comparison of HDL from homologous human plasma and follicular fluid. A model for extravascular fluid.

In the preovulatory period, follicular fluid contains only HDL. Biochemical characterization of such lipoproteins showed that follicular fluid HDLs were cholesterol-poor particles compared with serum HDLs, whereas the amount of phospholipids, expressed as percent weight, was significantly higher in follicular fluid HDLs (28.5%) than in serum HDLs (25.0%, P < .05). The amount of apolipoprotein (apo) A-IV per apo A-I was significantly higher in follicular fluid than in serum (0.77 versus 0.58 mg/g apo A-I, P < .02). To explore the role of HDLs as cholesterol acceptors in physiological media, we compared the ability of either whole human follicular fluids or homologous sera to promote cellular cholesterol efflux using Fu5AH rat hepatoma cells. At equivalent concentrations of HDL cholesterol in follicular fluid and in serum, t1/2 values for cholesterol efflux were in the same range. In addition, estimated maximal efflux values were not significantly different in follicular fluid and serum (45.9% and 49.6%, respectively), as were K(m) values (0.064 and 0.071 mmol/L HDL cholesterol respectively). In addition, isolated HDLs displayed the same capacity to promote cellular cholesterol efflux in both media. Thus, the kinetics and dose-response data between these two physiological media showed that HDLs play the major role in cellular cholesterol efflux. The rate of cholesterol esterification, as measured in the presence of cells, was significantly higher in follicular fluid than in serum at constant HDL cholesterol concentrations, whereas the rate of esterified cholesterol transfer toward added LDL was lower. In contrast, in a cell-free system, lecithin:cholesterol acyltransferase activity represented only 26% of that in serum HDL, whereas cholesterol ester transfer protein activities were comparable. In summary, in this particular model, we confirmed the essential role of HDLs as physiological acceptors in the removal of cellular cholesterol.

Animals↗