Dislocation of the hips in children with bilateral spastic cerebral palsy, 1985-2000.

The aim of this study was to assess the rate of hip dislocation at different ages in children with bilateral spastic cerebral palsy attending special schools in southern Derbyshire, UK, between 1985 and 2000. The medical notes of 110 individuals (68 males, 42 females) were obtained. They were divided into four groups according to the Gross Motor Function Classification System (GMFCS). We determined whether or not their hips were dislocated at the ages of 5, 10, and 15 years, and the kind of surgery performed in each case. The percentage of individuals with one or both hips dislocated increased with age and with severity of disease. Of those in GMFCS Level II (n=18), none had dislocations; Level III (n=16), none had dislocations at ages 5 and 10, but 11% had by the age of 15; Level IV (n=35), 8% had dislocations by age 5, 19% by age 10, and 30% by age 15; Level V (n=41), 22% had dislocations by age 5, 48% by age 10, and 50% by age 15. Forty-two per cent of individuals with hip dislocation had not had previous preventive surgery. Twenty-one per cent of hips operated on still proceeded to dislocation. We conclude that there was a high rate of hip dislocation, especially in GMFCS groups Levels IV and V, and that this often occurred very early. Preventive surgery avoided dislocation in many children. However, orthopaedic referral was often not made before dislocation was discovered, or the referral was made too late for surgery on soft tissue to be successful. These results may be compared with those from current programmes of hip management, involving radiological surveillance and early use of conservative and surgical interventions.

Botulinum toxin for cerebral palsy; where are we now?

In this article, the evidence base for botulinum-A treatment acquired in recent years is outlined, and the practicalities involved in providing this service are described. Botulinum-A is relatively new, and possible improvements for the future are considered.

Use of a lying hip abduction system in children with bilateral cerebral palsy: a pilot study.

Fourteen children aged 4 to 14 years with hip subluxation due to cerebral palsy (CP) were considered for a trial in a lying hip abduction system (Jenx Dreama, Jenx Limited, Sheffield, UK). Baseline data were recorded for 6 months, then assessments of the system were made for one year at 6 and 12 months. Assessments consisted of hip radiographs in the standard position, a parental questionnaire, and a sleep chart, which was completed by parents every Friday night during the trial. Three children could not enter the trial because of general sleep problems, and three could not complete it because they were unable to sleep with the system. One further child withdrew from the study just before the end because of unacceptable deterioration for which surgery was needed. The remaining seven children completed the trial and there was an overall improvement in rate of hip migration percentage on the right from 7% per annum in the baseline period to 4% with the system (p<0.05). On the left, changes were -3% and 0% respectively (ns). Average sleep at night changed from 9 to 9.4 hours (ns) and wakenings/night from 1 to 1.3 (ns). On the parental questionnaire, there were significant improvements noted with the system in position for seating and sleeping, ease of hip abduction for washing, and with pain reduction. This pilot study supports the use of this type of lying system but further studies are needed to establish the acceptability and efficacy of these systems, particularly in children aged 2 to 5 years when irreversible bony deformities of the hip tend to occur.

Markedly elevated lipid transfer inhibitor protein in hypercholesterolemic subjects is mitigated by plasma triglyceride levels.

Lipid transfer inhibitor protein (LTIP, apolipoprotein F) regulates the interaction of cholesteryl ester transfer protein (CETP) with lipoproteins and is postulated to enhance the ability of CETP to stimulate reverse cholesterol transport. The factors that regulate LTIP levels and control its biosynthesis are unknown. Here, we demonstrate that plasma LTIP is dramatically increased (3-fold) in hypercholesterolemic subjects with normal to mildly elevated plasma triglyceride (TG) levels compared with control subjects. LTIP in these subjects is not correlated with the extent of hypercholesterolemia or with low density lipoprotein (LDL), high density lipoprotein, or CETP levels. However, unlike CETP, LTIP levels correlate negatively with plasma TG levels. This association does not appear to reflect decreased LTIP synthesis, inasmuch as conditions that stimulate TG synthesis and secretion (200 micromol/L oleate) do not reduce LTIP secretion by SW872 or Caco-2 cells. In contrast, native or acetyl LDL stimulates LTIP secretion 2-fold. Importantly, although plasma LTIP typically resides on LDL, up to 25% of LTIP is bound to very low density lipoprotein when this lipoprotein is enriched in cholesteryl esters, as occurs in hypercholesterolemia. In summary, LTIP levels are markedly elevated by hypercholesterolemia; however, plasma TG levels attenuate this response. We hypothesize that this arises from an increased association of LTIP with very low density lipoprotein, leading to a more rapid clearance of the inhibitor from circulation.

Assessment of upper-limb function and movement in children with cerebral palsy wearing lycra garments.

It has recently been suggested that lycra garments are helpful for children with cerebral palsy (CP). Twelve children, with athetosis, ataxia, and spasticity, were fitted with lycra garments (Kendall-Camp UK Ltd). Scores on the Paediatric Evaluation of Disability Inventory (PEDI) scales were determined before and after wearing the garment for at least 6 hours a day for 6 weeks. Five children with motor problems representative of the whole group were investigated during a reach-and-grasp task by kinematic motion analysis; reflective markers were used with and without the garment. Carers were given a questionnaire concerning the practicalities of using the garments. All 12 children made improvements in at least one of the functional scales of the PEDI, and scores for the whole group showed significant gains (Wilcoxon chi2 test, self-help p<0.01; mobility p<0.5; social p<0.1). These changes were usually slight, although noticed by carers. Six children made gains of at least one scale of the caregiver assistance scores, two of the children showed losses (due to difficulties removing the garment for toileting), and four showed no change. Motion analysis indicated that (1) two children with athetosis had improved proximal stability in sitting and in smoothness of arm movements, (2) one child with ataxia had improved in proximal and distal stability, and (3) two children with spasticity had more jerky movements, although one improved in proximal stability. All children had problems in wearing the garments, including problems with toileting and incontinence of urine; the parents of only one child wanted to continue using it. Results suggest that the functional benefit of lycra garments for children with CP is mainly due to improvements in proximal stability but this should be weighed against the inconvenience and loss of independence.

Cholesteryl ester transfer protein biosynthesis and cellular cholesterol homeostasis are tightly interconnected.

Cholesteryl ester transfer protein (CETP) mediates triglyceride and cholesteryl ester (CE) transfer between lipoproteins, and its activity is strongly modulated by dietary cholesterol. To better understand the regulation of CETP synthesis and the relationship between CETP levels and cellular lipid metabolism, we selected the SW872 adipocytic cell line as a model. These cells secrete CETP in a time-dependent manner at levels exceeding those observed for Caco-2 or HepG2 cells. The addition of LDL, 25OH-cholesterol, oleic acid, or acetylated LDL to SW872 cells increased CETP secretion (activity and mass) up to 6-fold. In contrast, CETP production was decreased by almost 60% after treatment with lipoprotein-deficient serum or beta-cyclodextrin. These effects, which were paralleled by changes in CETP mRNA, show that CETP biosynthesis in SW872 cells directly correlates with cellular lipid status. To investigate a possible, reciprocal relationship between CETP expression and cellular lipid homeostasis, CETP biosynthesis in SW872 cells was suppressed with CETP antisense oligonucleotides. Antisense oligonucleotides reduced CETP secretion (activity and mass) by 60% compared with sense-treated cells. When CETP synthesis was suppressed for 24 h, triglyceride synthesis was unchanged, but cholesterol biosynthesis was reduced by 20%, and acetate incorporation into CE increased 31%. After 3 days of suppressed CETP synthesis, acetate incorporation into the CE pool increased 3-fold over control. This mirrored a similar increase in CE mass. The efflux of free cholesterol to HDL was the same in sense and antisense-treated cells; however, HDL-induced CE hydrolysis in antisense-treated cells was diminished 2-fold even though neutral CE hydrolase activity was unchanged. Thus, CETP-compromised SW872 cells display a phenotype characterized by inefficient mobilization of CE stores leading to CE accumulation. These results strongly suggest that CETP expression levels contribute to normal cholesterol homeostasis in adipocytic cells. Overall, these studies demonstrate that lipid homeostasis and CETP expression are tightly coupled.

Co-existence of lysosomal storage diseases in a consanguineous family.

Lysosomal storage diseases are rare and coexistence of more than one in a family can present a diagnostic challenge as illustrated by this study. The index case born to consanguineous Asian parents presented with developmental delay. Investigations led to an incidental finding of Fabry disease. After numerous additional investigations over a year, a second diagnosis of aspartylglucosaminuria (AGU) was made. A family history of renal disease and developmental delay was disclosed. The sister and first cousin of the index case were diagnosed as homozygous for AGU, but do not have Fabry disease. The younger brother has since been diagnosed with both Fabry disease and AGU. Another cousin has learning difficulties and fits, but is heterozygous for AGU, and possibly has another uncharacterised autosomal recessive disorder. In a family with consanguinity when the clinical picture in an individual is not fully explained by the presence of one rare metabolic disease, it is essential to investigate further for the presence of others.

Elevated triglyceride content diminishes the capacity of high density lipoprotein to deliver cholesteryl esters via the scavenger receptor class B type I (SR-BI).

The selective uptake of high density lipoprotein (HDL) cholesteryl ester (CE) by the scavenger receptor class B type I (SR-BI) is well documented. However, the effect of altered HDL composition, such as occurs in hyperlipidemia, on this important process is not known. This study investigated the impact of variable CE and triglyceride (TG) content on selective uptake. CE selective uptake by Y1 and HepG2 cells was strongly affected by modification of either the CE or TG content of HDL. Importantly, TG, like CE, was selectively taken up by a dose-dependent, saturable process in these cells. As shown by ACTH up-regulation and receptor overexpression experiments, SR-BI mediated the selective uptake of both CE and TG. With in vitro modified HDLs of varying CE and TG composition, the selective uptake of CE and TG was dependent on the abundance of each lipid within the HDL particle. Furthermore, total selective uptake (CE + TG) remained constant, indicating that these lipids competed for cellular uptake. These data support a novel mechanism whereby SR-BI binds HDL and mediates the incorporation of a nonspecific portion of the HDL lipid core. In this way, TG directly affects the ability of HDL to donate CE to cells. Processes that raise the TG/CE ratio of HDL will impair the delivery of CE to cells via this receptor and may compromise the efficiency of sterol balancing pathways such as reverse cholesterol transport.

Feeding efficiency and respiratory integration in infants with acute viral bronchiolitis.

OBJECTIVE: To examine the effects of bronchiolitis on feeding efficiency and respiratory integration. STUDY DESIGN: We studied 21 infants with bronchiolitis and 21 bottle-fed healthy infants who formed a comparison group. Repeat evaluations of half the bronchiolitis group were performed during recovery. During each feeding study we measured the duration and frequency of sucking, the frequency of single and multiple swallows, the respiratory rate, the postswallow respiratory direction, and the suck and swallow volumes. RESULTS: The infants with bronchiolitis devoted significantly less time to sucking than their healthy peers (P <.05), and the mean suck volume was reduced. Although the frequency of swallowing was slightly higher, the volume of milk consumed per swallow was almost half the amount consumed by the comparison group (P <.01). Coordination of breathing with swallowing was also less effective (P <.01). CONCLUSION: Although most aspects of feeding are less efficient during periods of respiratory illness, others are preserved or recover rapidly. Coordination of breathing during feeding is also significantly impaired.

An evaluation of lycra garments in the lower limb using 3-D gait analysis and functional assessment (PEDI).

Whole body lycra garments were assessed in eight children using gait analysis, the paediatric evaluation of disability index (PEDI), and a questionnaire of parental acceptance. Seven of the children had cerebral palsy and one Duchennes muscular dystrophy. After initial assessment and fitting of the garment, there was a 2-week introduction period followed by 6 weeks of wearing the garment for at least 6 h everyday, following which they were re-assessed. The root mean square error (RMSE) was used as a measure of variability over three separate passes through the gait laboratory and was a reference figure for gait stability. Proximal stability around the pelvis improved for five children and distal stability improved for three. Five children improved in at least one aspect of the PEDI scale. Although the parents and children detected these improvements, they did not outweigh the disadvantages of wearing the suit and as a consequence only one out of eight families considered continuing with the lycra garment.

The capacity of various non-esterified fatty acids to suppress lipid transfer inhibitor protein activity is related to their perturbation of the lipoprotein surface.

Lipid transfer inhibitor protein (LTIP) regulates cholesteryl ester transfer protein (CETP) activity by selectively impeding lipid transfer events involving low density lipoproteins (LDLs). We previously demonstrated that LTIP activity is suppressed in a dose-dependent manner by sodium oleate and that its activity can be blocked by physiological levels of free fatty acids [R.E. Morton, D. J. Greene, Arterioscler. Thromb. Vasc. Biol. 17 (1997)]. These data further suggested that palmitate has greater LTIP suppressive activity than oleate. In this report we define the ability of the major non-esterified fatty acids (NEFAs) in plasma to modulate LTIP activity. The greater suppression of LTIP activity by palmitate compared to oleate noted above was also seen in lipid transfer assays with various lipoprotein substrates and in the presence of albumin, showing that the relative effects of these two NEFAs are independent of assay conditions. To assess the effect of other NEFAs on LTIP activity, pure NEFAs were added to assays containing (3)H-cholesteryl ester labeled LDLs, unlabeled high density lipoproteins (HDLs) and CETP+/-LTIP. Whereas myristate, palmitate, stearate, oleate and linoleate stimulated CETP activity to varying extents, all NEFAs suppressed LTIP activity. Among these NEFAs, LTIP suppressive activity was greatest for the long-chain saturated and monounsaturated NEFAs. In contrast, linoleate and myristate were poor inhibitors of LTIP activity. The effects of increasing amounts of a given NEFA on LTIP activity correlated well with the increase in LDL negative charge induced by that NEFA, yet this relationship was unique for each NEFA, especially stearate. Notably, as measured by fluorescence anisotropy, the suppression of LTIP was highly and negatively correlated with the decreased order in the molecular packing of lipoprotein surface phospholipids caused by all NEFAs. Long-chain, saturated and monounsaturated NEFAs appear to be most effective in this regard partly because of their preferential association with LDLs where LTIP inhibition likely takes place. We hypothesize that NEFAs suppress LTIP activity by perturbing the surface properties of LDLs and counteracting the heightened molecular packing normally caused by LTIP. Diets rich in long-chain saturated and monounsaturated fatty acids may lead to a greater suppression of LTIP activity in vivo, which would allow LDLs to participate more actively in CETP-mediated lipid transfer reactions.

Air swallowing in Rett syndrome.

The possible causes of excessive swallowing of air leading to bloating, which is common in Rett syndrome (RS), were investigated during feeding and at rest. Seven individuals with RS aged between 4 and 33 years (three with air bloat) underwent feeding videoflouroscopy and concurrent respiration monitoring. The results were compared with a randomly selected group of 11 individuals, aged between 2 and 16 years, with quadriplegic cerebral palsy and feeding problems, some of whom had mild air bloat. All individuals from both groups had isolated pharyngeal swallows and several mouth breathed; this may account for some air swallowing but not the severe air bloat characteristic of RS. Thirty-three individuals with RS aged between 3 and 44 years were monitored for nasal respiration, chest movements, swallowing, and vocal cord position at rest (between feeding). Twenty had air bloat, 17 of whom swallowed air during breath-holding in the same way, and three gulped air during hyperventilation. Of the 13 without air bloat, eight did not have recurrent breath-holding and five did, but without concurrent air swallowing. Several methods for reducing air swallowing in apnoea were investigated. The most successful was a dummy with an air leak, but this was poorly tolerated and could only be used for short periods of time. Apnoeas and air bloat are often worse when individuals are distressed and may in some individuals be reduced by anxiolytic medications.

Cholesteryl ester transfer protein and its plasma regulator: lipid transfer inhibitor protein.

The interconnections between cholesteryl ester transfer protein (CETP) expression and lipid metabolism, and the possible roles of CETP in atherogenesis are examined. The importance of lipid transfer inhibitor protein in modulating CETP activity is detailed, and the consequences of this inhibitory activity on CETP-mediated events are proposed.

Respiratory tract infections due to direct and reflux aspiration in children with severe neurodisability.

Lower respiratory tract infections in children with severe neurodisability are usually caused by aspiration of stomach contents from gastroesophageal reflux (GOR) or direct aspiration (DA) of food due to oral and pharyngeal motor problems. To determine the contributions and interactions of GOR and DA, oesophageal 24-hour pH monitoring and feeding videofluoroscopy were performed in 34 children (age range 7 months to 16 years, mean 7 years) who had severe physical and learning disabilities and who were slow feeders. Subjects were divided into three groups according to the frequency of their respiratory tract infections. Subjects in group 1 had no respiratory tract infections (N=10); five had GOR and none had DA. Subjects in group 2 had minor respiratory tract infections but had not received more than one course of antibiotics for this in the previous year (N=8); two had GOR alone, four had DA alone, and two had neither. All subjects in group 3 had recurrent respiratory tract infections (N=16); one had GOR alone, seven had DA alone, and eight had both GOR and DA. This study suggests that oral and pharyngeal motor problems are the major cause of respiratory tract infection in children with severe neurodisability. These problems lead to DA and, if GOR is present, to the aspiration of stomach contents. Those children with both DA and GOR are more likely to have severe respiratory tract infections which may lead to gastrostomy feeding (together with fundoplication). GOR without sufficient oral and pharyngeal motor problems to cause DA is less likely to cause respiratory tract infection in children with severe neurodisability.

Lipid transfer inhibitor protein defines the participation of lipoproteins in lipid transfer reactions: CETP has no preference for cholesteryl esters in HDL versus LDL.

Cholesteryl ester transfer protein (CETP) catalyzes the net transfer of cholesteryl ester (CE) between lipoproteins in exchange for triglyceride (heteroexchange). It is generally held that CETP primarily associates with HDL and preferentially transfers lipids from this lipoprotein fraction. This is illustrated in normal plasma where HDL is the primary donor of the CE transferred to VLDL by CETP. However, in plasma deficient in lipid transfer inhibitor protein (LTIP) activity, HDL and LDL are equivalent donors of CE to VLDL (Arterioscler Thromb Vasc Biol. 1997;17:1716-1724). Thus, we have hypothesized that the preferential transfer of CE from HDL in normal plasma is a consequence of LTIP activity and not caused by a preferential CETP-HDL interaction. We have tested this hypothesis in lipid mass transfer assays with partially purified CETP and LTIP, and isolated lipoproteins. With a physiological mixture of lipoproteins, the preference ratio (PR, ratio of CE mass transferred from a lipoprotein to VLDL versus its CE content) for HDL and LDL in the presence of CETP alone was approximately 1 (ie, no preference). Fourfold variations in the LDL/HDL ratio or in the levels of HDL in the assay did not result in significant preferential transfer from any lipoprotein. On addition of LTIP, the PR for HDL was increased up to 2-fold and that for LDL decreased in a concentration-dependent manner. Under all conditions where LDL and HDL levels were varied, LTIP consistently resulted in a PR >1 for CE transfer from HDL. Short-term experiments with radiolabeled lipoproteins and either partially purified or homogenous CETP confirmed these observations and further demonstrated that CETP has a strong predilection to mediate homoexchange (bidirectional transfer of the same lipid) rather than heteroexchange (CE for TG); LTIP had no effect on the selection of CE or TG by CETP or its mechanism of action. We conclude, in contrast to current opinion, that CETP has no preference for CE in HDL versus LDL, suggesting that the previously reported stable binding of CETP to HDL does not result in selective transfer from this lipoprotein. These data suggest that LTIP is responsible for the preferential transfer of CE from HDL that occurs in plasma. CETP and LTIP cooperatively determine the extent of CETP-mediated remodeling of individual lipoprotein fractions.

Molecular cloning and expression of lipid transfer inhibitor protein reveals its identity with apolipoprotein F.

Published studies demonstrate that lipid transfer inhibitor protein (LTIP) is an important regulator of cholesteryl ester transfer protein (CETP) activity. Although LTIP inhibits CETP activity among different lipoprotein classes, it preferentially suppresses transfer events involving low density lipoprotein (LDL), whereas transfers involving high density lipoprotein as donor are less affected. In this study, we report the purification of LTIP and the expression of its cDNA in cultured cells. Purification of LTIP, in contrast to other published protocols, took advantage of the tight association of this protein with LDL. Ultracentrifugally isolated LDL was further purified on anti-apoE and apoA-I affinity columns. Affinity purified LDL was delipidated by tetramethylurea, and the tetramethylurea-soluble proteins were separated by SDS-polyacrylamide gel electrophoresis. The protein migrating at a molecular mass of approximately 33 kDa was excised from the gel and its N-terminal amino acid sequence determined. The 14-amino acid sequence obtained showed complete homology with the sequence deduced for apolipoprotein F (apoF) cDNA isolated from Hep G2 cells. On Western blots, peptide-specific antibodies raised against synthetic fragments of apoF reacted with the same 33-kDa protein in LTIP-containing fractions purified from LDL and from lipoprotein-deficient plasma. In contrast to that previously reported, apoF was shown to be associated almost exclusively with LDL, identical to the distribution of LTIP activity. The cDNA for apoF was cloned from a human liver cDNA library, ligated into a mammalian expression vector, and transiently transfected into COS-7 cells. Conditioned media containing secreted apoF demonstrated CETP inhibitor activity, whereas cells transfected with vector alone did not. This CETP inhibitor activity was efficiently removed from the media by nickel-Sepharose, consistent with the 6-His tag incorporated into recombinant apoF. By Western blot, the 6-His-tagged protein had a molecular weight slightly larger than native apoF. The CETP inhibitor activity of recombinant apoF possessed the same LDL specificity, oleate sensitivity, and dependence on lipoprotein concentration as previously noted for LTIP. We conclude that LTIP and apoF are identical.

Lysophosphatidic acid as a potential biomarker for ovarian and other gynecologic cancers.

CONTEXT: Lysophosphatidic acid (LPA) has been shown to stimulate proliferation of ovarian cancer cells and is present in the ascitic fluid of patients with ovarian cancer. OBJECTIVES: To determine whether elevated levels of LPA are present in plasma from patients with ovarian cancer and other gynecologic malignancies compared with healthy controls and to evaluate whether an elevated LPA plasma level may be a biomarker for these diseases. DESIGN: A research assay was used to measure total LPA levels in plasma from healthy women and women with different diseases. All LPA assays and comparison of LPA levels and CA125 (an ovarian cancer biomarker) levels were performed by observers blinded to patient status or group. SETTING: The Cleveland Clinic Foundation. PARTICIPANTS: A convenience sample of 48 healthy control women, 48 women with ovarian cancer, 36 women with other gynecologic cancers, 17 women with benign gynecologic diseases, 11 women with breast cancer, and 5 women with leukemias. MAIN OUTCOME MEASURES: Total LPA levels in plasma samples from patients and controls. RESULTS: Patients in the ovarian cancer group had significantly higher plasma LPA levels (mean, 8.6 micromol/L; range, 1.0-43.1 micromol/L) compared with the healthy control group (mean, 0.6 micromol/L; range, <0.1-6.3 micromol/L) (P<.001). Elevated plasma LPA levels were detected in 9 of 10 patients with stage I ovarian cancer, 24 of 24 patients with stage II, III, and IV ovarian cancer, and 14 of 14 patients with recurrent ovarian cancer. Of 36 patients with other gynecologic cancers, 33 also showed higher LPA levels(mean, 14.9 micromol/L; range, <0.1-63.2 pmol/L), compared with healthy controls (P<.001). Elevated plasma LPA levels were detected in 5 of 48 controls and 4 of 17 patients with benign gynecologic diseases and in no women with breast cancer or leukemia. In comparison, among a subset of patients with ovarian cancer, 28 of 47 had elevated CA125 levels, including 2 of 9 patients with stage I disease. CONCLUSIONS: Plasma LPA levels may represent a potential biomarker for ovarian cancer and other gynecologic cancers. However, these findings are preliminary and require confirmation in larger studies.

Phorbol 12-myristate 13-acetate stimulates lysophosphatidic acid secretion from ovarian and cervical cancer cells but not from breast or leukemia cells.

Lysophosphatidic acid (LPA) is present in ascites from patients with ovarian cancer. It stimulates calcium release and growth of ovarian cancer cells both in vitro and in vivo. Recently, we found that LPA levels were significantly elevated in plasma from patients with ovarian cancer and other gynecological cancers. In contrast, LPA levels were not elevated in patients with breast cancer and leukemias. In view of this, we investigated whether gynecological cancer cells could produce LPA. LPA was extracted from the supernatant of cells cultured in vitro and purified by thin layer chromatography. After hydrolysis and transmethylation, the fatty acid derivatives were analyzed by gas chromatography. We found that the phorbol ester, phorbol 12-myristate 13-acetate (PMA), significantly stimulated the production of LPA in ovarian and cervical cancer cells. In contrast, a small or negligible amount of LPA was produced in breast cancer and leukemia cells upon PMA stimulation. This cell type specificity correlates with our values of plasma LPA, suggesting that gynecological tumor cells may be an important source of the elevated LPA noted in the plasma of patients with these cancers. The cytosolic PLA2 (cPLA2)/Ca2+-independent PLA2 (iPLA2) inhibitor, AACOCF3, inhibited 75.6% PMA-stimulated LPA secretion in ovarian cancer cells, suggesting a cPLA2/iPLA2 activity was involved in LPA production from ovarian cancer cells.

Suppression of lipid transfer inhibitor protein activity by oleate. A novel mechanism of cholesteryl ester transfer protein regulation by plasma free fatty acids.

Cholesteryl ester transfer protein (CETP) mediates the interlipoprotein exchange of cholesteryl ester (CE) and triglyceride. A second plasma protein, lipid transfer inhibitor protein (LTIP), binds to lipoproteins and inhibits CETP activity by displacing CETP from the lipoprotein surface. Since free fatty acids (FFAs) enhance the binding of CETP to lipoproteins, we have examined the possible role of FFAs in modulating LTIP activity. Partially purified CETP, LTIP, and lipoproteins were incubated with 0 to 30 mumol/L sodium oleate, and the transfer of CE between a labeled donor lipoprotein and a given acceptor lipoprotein was measured. Without LTIP, oleate stimulated CETP-mediated CE transfer between VLDL, LDL, and HDL up to threefold. This stimulation was unique in both magnitude and oleate concentration dependence for each donor-acceptor lipoprotein pair. In contrast to CETP activity, in transfer reactions involving LDL or VLDL as donor, LTIP activity was suppressed (> 80%) by 10 to 15 mumol/L oleate. LTIP activity in transfer reactions with HDL as donor was less sensitive. Similar results to these were observed when lipid transfer reactions were measured in the total lipoprotein fraction isolated from FFA-enriched plasma. The FFA content of lipoproteins was strongly influenced by the concentration of FFA in plasma; lipoprotein FFA levels sufficient to suppress LTIP activity by 50% to 100% were achieved in plasma containing 0.8 to 1.0 mmol/L FFA. We conclude that LTIP may be functionally inactive during periods of transient elevations of plasma FFA levels, such as during postprandial lipemia or overnight fasting, or chronically suppressed in disease states in which plasma FFA levels are increased. The suppression of LTIP activity by FFA allows for maximum CETP-mediated lipid transfer between all lipoproteins, including lipid transfer reactions involving LDL that are normally preferentially suppressed by LTIP.