EuGMS Task and Finish group on Fall-Risk-Increasing Drugs (FRIDs): Position on Knowledge Dissemination, Management, and Future Research.

Falls are a major public health concern in the older population, and certain medication classes are a significant risk factor for falls. However, knowledge is lacking among both physicians and older people, including caregivers, concerning the role of medication as a risk factor. In the present statement, the European Geriatric Medicine Society (EuGMS) Task and Finish group on fall-risk-increasing drugs (FRIDs), in collaboration with the EuGMS Special Interest group on Pharmacology and the European Union of Medical Specialists (UEMS) Geriatric Medicine Section, outlines its position regarding knowledge dissemination on medication-related falls in older people across Europe. The EuGMS Task and Finish group is developing educational materials to facilitate knowledge dissemination for healthcare professionals and older people. In addition, steps in primary prevention through judicious prescribing, deprescribing of FRIDs (withdrawal and dose reduction), and gaps in current research are outlined in this position paper.

EuGMS Task and Finish group on Fall-Risk-Increasing Drugs (FRIDs): Position on Knowledge Dissemination, Management, and Future Research.

Falls are a major public health concern in the older population, and certain medication classes are a significant risk factor for falls. However, knowledge is lacking among both physicians and older people, including caregivers, concerning the role of medication as a risk factor. In the present statement, the European Geriatric Medicine Society (EuGMS) Task and Finish group on fall-risk-increasing drugs (FRIDs), in collaboration with the EuGMS Special Interest group on Pharmacology and the European Union of Medical Specialists (UEMS) Geriatric Medicine Section, outlines its position regarding knowledge dissemination on medication-related falls in older people across Europe. The EuGMS Task and Finish group is developing educational materials to facilitate knowledge dissemination for healthcare professionals and older people. In addition, steps in primary prevention through judicious prescribing, deprescribing of FRIDs (withdrawal and dose reduction), and gaps in current research are outlined in this position paper.

Polypharmacy and falls in the middle age and elderly population.

AIM: Falls in the elderly are common and often serious. We studied the association between multiple drug use (polypharmacy) and falls in the elderly. METHODS: This was a population-based cross-sectional study, part of the Rotterdam Study. The participants were 6928 individuals aged > or = 55 years. The prevalence of falls in the previous year was assessed. Medication use was determined with an interviewer-administered questionnaire with verification of use. Polypharmacy was defined as the use of four or more drugs per day. RESULTS: The prevalence of falls strongly increased with age. Falls were more common in women than in men. Fall risk increased with increasing disability, presence of joint complaints, use of a walking aid and fracture history. The risk of falling increased significantly with the number of drugs used per day (P for trend < 0.0001). After adjustment for a large number of comorbid conditions and disability, polypharmacy remained a significant risk factor for falling. Stratification for polypharmacy with or without at least one drug which is known to increase fall risk (notably CNS drugs and diuretics) disclosed that only polypharmacy with at least one risk drug was associated with an increased risk of falling. CONCLUSIONS: Fall risk is associated with the use of polypharmacy, but only when at least one established fall risk-increasing drug was part of the daily regimen.

Blockade of the alpha 2-macroglobulin receptor/low-density-lipoprotein-receptor-related protein on rat liver parenchymal cells by the 39-kDa receptor-associated protein leaves the interaction of beta-migrating very-low-density lipoprotein with the lipoprotein remnant receptor unaffected.

The nature of the liver binding site which is responsible for the initial recognition and clearance of chylomicron-remnants and beta-migrating very-low-density lipoprotein (beta-VLDL) is under active dispute. We have investigated the effect of the 39-kDa receptor-associated protein (RAP) on the recognition site for activated alpha 2-macroglobulin and beta-VLDL on rat liver parenchymal cells in vivo and in vitro in order to analyze whether both substrates are recognized and internalized by the same receptor system. Radiolabelled trypsin-activated alpha 2-macroglobulin (alpha 2M-T) was cleared rapidly by the liver (maximal uptake of 80.8 +/- 1.0% of the injected dose). Prior injection of 5, 15, or 50 mg gluthathione-S-transferase-linked RAP (GST-RAP)/kg rat reduced the liver uptake to 62.2 +/- 2.3%, 59.3 +/- 1.1%, or 2.9 +/- 0.1% of the injected dose, respectively. Concurrently the serum decay was strongly delayed after injection of 50 mg GST-RAP/kg rat but this did not affect the serum decay and liver uptake of 125I-beta-VLDL. Binding studies with isolated liver parenchymal cells in vitro demonstrated that the binding of 125I-alpha 2M-T was 98% inhibited by GST-RAP with an IC50 of 0.3 microgram/ml (4.2 nM), whereas the binding of 125I-beta-VLDL and 125I-beta-VLDL + recombinant apolipoprotein E (rec-apoE) was unaffected by GST-RAP up to 50 micrograms/ml (700 nM). Also, the cell association and degradation of alpha 2M-T was blocked by RAP, while the association and degradation of beta-VLDL and beta-VLDL + rec-apoE were not influenced. The inhibitory effect of RAP on the cell association and degradation of alpha 2M-T lasted for 1-2 h of incubation at 37 degrees C. The binding of the radioiodinated RAP to isolated liver parenchymal cells was highly efficiently coupled to lysosomal degradation. Upon in vivo injection into rats, 125I-labeled RAP is rapidly cleared from the serum and taken up by the liver, which is also coupled to efficient degradation. Since RAP blocks binding of all known ligands to the alpha 2-macroglobulin receptor/low-density lipoprotein receptor-related protein (the alpha 2Mr/LRP) and at high concentrations the binding to the LDL receptor, we conclude that the initial binding and internalization of beta-VLDL by rat liver parenchymal cells is not mediated by the alpha 2Mr/LRP. The properties of binding of beta-VLDL to rat liver parenchymal cells points to an apoE-specific recognition site for lipoprotein remnants which differs from the alpha 2Mr/LRP, proteoglycans and the LDL receptor and is tentatively called the lipoprotein remnant receptor.

Recognition of lactoferrin and aminopeptidase M-modified lactoferrin by the liver: involvement of the remnant receptor.

Lactoferrin inhibits the hepatic uptake of lipoprotein remnants, and we showed earlier that arginine residues of lactoferrin are involved. In this study, lactoferrin was treated with aminopeptidase-M (APM), which resulted in removal of 14 N-terminal amino acids, including 4 clustered arginines at positions 2-5 (APM-lactoferrin). After i.v. injection into rats, 125I-APM-lactoferrin was cleared within 10 min by the liver parenchymal cells (74.7% of the dose). Binding of APM-lactoferrin to isolated parenchymal liver cells was saturable with a Kd of 186 nM (750.000 sites/cell). This is in striking contrast to the binding of lactoferrin (Kd 10 microM; 20 x 10(6) sites/cell). Preinjection of rats with 20 mg of APM-lactoferrin/kg body weight reduced the liver association of beta-VLDL by 50%, whereas lactoferrin had no effect at this dose. With isolated parenchymal liver cells, APM-lactoferrin was a more effective competitor for beta-VLDL binding than native lactoferrin (50% inhibition at 0.5 mg/ml vs. 8.0 mg/ml). We conclude that the 4-arginine cluster of lactoferrin at position 2-5 involved in the massive association of lactoferrin with the parenchymal liver cell, but is not essential for the inhibition of the lipoprotein remnant uptake. The Arg/Lys sequence at position 25-30, which resembles the binding site of apoE, may mediate the high affinity binding of lactoferrin and block the binding of beta-VLDL to the remnant receptor efficiently.

Recognition of lactoferrin and aminopeptidase M-modified lactoferrin by the liver: involvement of proteoglycans and the remnant receptor.

1. Lactoferrin and aminopeptidase M-modified lactoferrin (APM-lactoferrin; which lacks its 14 N-terminal amino acids) inhibit the liver uptake of lipoprotein remnant. In the present study, the role of proteoglycans in the initial interaction of beta-migrating very-low-density lipoprotein (beta-VLDL), native and APM-lactoferrin with isolated rat parenchymal liver cells was investigated. Treatment of the cells with chondroitinase lowered the Kd of lactoferrin binding (from 10 to 2.4 microM), and the number of sites/cell (from 20 x 10(6) to 7 x 10(6)), while heparinase treatment did not affect the binding. The binding characteristics of APM-lactoferrin and beta-VLDL were not altered by treatment of the cells with chondroitinase or heparinase. It is concluded that proteoglycans are not involved in the initial binding of APM-lactoferrin and beta-VLDL to parenchymal cells, while chondroitin sulphate proteoglycans are mainly responsible for the massive, low-affinity binding of native lactoferrin..2. The binding of lactoferrin, APM-lactoferrin and beta-VLDL to parenchymal liver cells was not influenced by the glutathione S-transferase-receptor-associated protein (GST-RAP) (97.2% +/- 4.0%, 95.5 +/- 3.7% and 98.5% of the control binding), while the binding of alpha 2-macroglobulin was fully blocked at 10 micrograms/ml GST-RAP (1.8 +/- 0.5% of the control binding). Since GST-RAP blocks the binding of all the known ligands to the low-density lipoprotein (LDL)-receptor-related protein (LRP), it is concluded that LRP is not the initial primary recognition site for lactoferrin, APM-lactoferrin and beta-VLDL on parenchymal liver cells. 3. We showed earlier that.APM-lactoferrin, as compared with lactoferrin, is a more effective inhibitor of the liver uptake of lipoprotein remnants (49.4 +/- 4.0% versus 80.8 +/- 4.8% of the control at 500 micrograms/ml respectively). We found in the present study that beta-VLDL is able to inhibit the binding of APM-lactoferrin to parenchymal liver cells significantly (74.9 +/- 3.3% of the control; P < 0.002), while the lactoferrin binding was unaffected. It is concluded that a still unidentified specific recognition site (the putative remnant receptor) is responsible for the initial binding of remnants to parenchymal cells and it is suggested that the partial cross-competition between APM-lactoferrin and beta-VLDL may be of further help in the elucidation of the molecular nature of this recognition site.

LDL receptor-independent and -dependent uptake of lipoproteins.

The liver plays a decisive role in the regulation of the plasma levels of atherogenic lipoproteins. The primary liver interaction site for chylomicron-remnants and VLDL remnants (beta-VLDL) is still unidentified, while the subsequent cellular uptake is likely to be mediated in concert by the LDL receptor related protein (LRP) and the LDL receptor. The nature of the primary interaction site of remnants (remnant-receptor) might be a liver-specific proteoglycan or a liver-specific protein. Atherogenic modified LDL can be recognized by a family of scavenger-receptors. A newly identified 95-kDa protein forms the most likely candidate for mediating the in vivo uptake of oxidized LDL from the circulation and might thus protect the body against the presence of oxidized LDL in the blood compartment.

Lipoprotein receptors and atherogenic receptor-mediated mechanisms.

The liver plays a decisive role in the regulation of the plasma levels of atherogenic lipoproteins. The primary liver interaction site of chylomicron remnants and VLDL remnants (beta-VLDL) is still unidentified, whereas the subsequent cellular uptake is likely to be mediated in concert by the LDL receptor-related protein and the LDL receptor. The nature of the primary interaction site of remnants (remnant receptor) might be a liver-specific proteoglycan or a liver-specific protein. Atherogenic modified LDL can be recognized by a family of scavenger receptors. A newly identified 95 kDa protein forms the most likely candidate for mediating the in-vivo uptake of oxidized LDL from the circulation and may, therefore, protect the body against the presence of oxidized LDL in the blood compartment.

Removal of 14 N-terminal amino acids of lactoferrin enhances its affinity for parenchymal liver cells and potentiates the inhibition of beta- very low density lipoprotein binding.

Lactoferrin inhibits the hepatic uptake of lipoprotein remnants, and we showed earlier that arginine residues of lactoferrin are involved. In this study, lactoferrin was treated with aminopeptidase M (APM), which resulted in removal of 14 N-terminal amino acids, including 4 clustered arginine residues at positions 2-5 (APM-lactoferrin). After intravenous injection into rats, 125I-labeled APM-lactoferrin was cleared within 10 min by the liver parenchymal cells (74.7% of the dose). In contrast to native lactoferrin, APM-lactoferrin was rapidly internalized after liver association (> 80% of the liver-associated radioactivity was internalized within 10 min). Binding of APM-lactoferrin to isolated parenchymal liver cells was saturable with a Kd of 186 nM (750,000 sites/cell). This is in striking contrast to the binding of native lactoferrin (Kd 10 microM; 20 x 10(6) sites/cell). Preinjection of rats with 20 mg of APM-lactoferrin/kg of body weight reduced the liver association of beta-very low density lipoprotein (beta-VLDL) by 50%, whereas lactoferrin had no effect at this dose. With isolated parenchymal liver cells, APM-lactoferrin was a more effective competitor for beta-VLDL binding than native lactoferrin (50% inhibition at 0.5 mg/ml versus 8.0 mg/ml). Selective modification of the arginines of APM-lactoferrin with 1,2-cyclohexanedione reduced the liver association by approximately 60% and abolished the capacity of APM-lactoferrin to inhibit the binding of 125I-labeled beta-VLDL in vitro. In conclusion, our data indicate that the four-arginine cluster of lactoferrin at positions 2-5 is involved in its massive, low affinity association of lactoferrin with the liver, possibly to proteoglycans, but is not essential for the inhibition of lipoprotein remnant uptake. The Arg-Lys sequence at positions 25-31, which resembles the binding site of apolipoprotein E, may mediate the high affinity binding of lactoferrin and block the binding of beta-VLDL to the remnant receptor with high efficiency.

Lactoferrin uptake by the rat liver. Characterization of the recognition site and effect of selective modification of arginine residues.

Recently it was found that lactoferrin, an iron-binding glycoprotein with a molecular weight of 76,500, inhibits the remnant receptor-mediated uptake of apolipoprotein E (apoE)-bearing lipoproteins by the liver. In the present study we characterized the hepatic recognition of lactoferrin. Intravenously injected 125I-lactoferrin was cleared rapidly from the circulation by the liver (92.8 +/- 9.5% of the dose at 5 min after injection). Parenchymal cells contained 97.1 +/- 1.5% of the hepatic radioactivity. Internalization, monitored by measuring the release of liver-associated radioactivity by the polysaccharide fucoidin, occurred slowly. Only about 40% of the liver-associated lactoferrin was internalized at 10 min after injection, and it took 180 min to internalize 90%. Subcellular fractionation indicated that internalized lactoferrin is transported to the lysosomes. Binding of lactoferrin to isolated parenchymal liver cells was saturable with a dissociation constant of 10 microM (20 x 10(6) binding sites/cell). The role of arginine residues on lactoferrin was studied by modifying these residues with 1,2-cyclohexanedione. The modification resulted in a strongly reduced liver association (15.9 +/- 1.6% of the dose at 5 min after injection). Furthermore, unlabeled 1,2-cyclohexanedione-modified lactoferrin did not inhibit the binding of 125I-lactoferrin to isolated parenchymal cells. Arginine residues on lactoferrin thus appear to be essential for its specific recognition by parenchymal liver cells. In particular the clustered N-terminal arginine residues, which resemble the arginine-rich receptor binding sequence in apoE, may be responsible for both the interaction of lactoferrin with its recognition site and the inhibition of the hepatic uptake of apoE-bearing lipoproteins.

Characterization of the chylomicron-remnant-recognition sites on parenchymal and Kupffer cells of rat liver. Selective inhibition of parenchymal cell recognition by lactoferrin.

Upon injection of chylomicrons into rats, chylomicron remnants are predominantly taken up by parenchymal cells, with a limited contribution (8.6% of the injected dose) by Kupffer cells. In vitro storage of partially processed chylomicron remnants for only 24 h leads, after in vivo injection, to an avid recognition by Kupffer cells (uptake up to 80% of the total liver-associated radioactivity). Lactoferrin greatly reduces the liver uptake of chylomicron remnants, which appears to be the consequence of a specific inhibition of the uptake by parenchymal cells. Kupffer-cell uptake is not influenced by lactoferrin. In vitro studies with isolated parenchymal and Kupffer cells show that both contain a specific recognition site for chylomicron remnants. The Kupffer-cell recognition site differs in several ways from the recognition site on parenchymal cells as follows. (a) The maximum level of binding is 3.7-fold higher/mg cell protein than with parenchymal cells. (b) Binding of chylomicron remnants is partially dependent on the presence of calcium, while binding to parenchymal cells is not. (c) beta-Migrating very-low-density lipoprotein is a less effective competitor for chylomicron-remnant binding to Kupffer cells compared to parenchymal cells. (d) Lactoferrin leaves Kupffer-cell binding uninfluenced, while it greatly reduces binding of chylomicron remnants to parenchymal cells. The properties of chylomicron-remnant recognition by parenchymal cells are consistent with apolipoprotein E being the determinant for recognition. It can be concluded that the chylomicron-remnant recognition site on Kupffer cells possesses properties which are distinct from the recognition site on parenchymal cells. It might be suggested that partially processed chylomicron remnants are specifically sensitive to a modification, which induces an avid interaction with the Kupffer cells. The recognition site for (modified) chylomicron remnants on Kupffer cells might function as a protection system against the occurrence of these potential atherogenic chylomicron-remnant particles in the blood.

Recognition of chylomicron remnants and beta-migrating very-low-density lipoproteins by the remnant receptor of parenchymal liver cells is distinct from the liver alpha 2-macroglobulin-recognition site.

The uptake in vivo of chylomicrons and beta-migrating very-low-density lipoprotein (beta-VLDL) by rat liver, which is primarily carried out by parenchymal cells, is inhibited, 5 min after injection, to respectively 35 and 8% of the control values after preinjection of lactoferrin. The decrease in the uptake of lipoproteins by the liver caused by lactoferrin is a specific inhibition of uptake by parenchymal cells. Competition studies in vitro demonstrate that chylomicron remnants and beta-VLDL compete for the same recognition site on parenchymal cells. Data obtained in vivo together with the competition studies performed in vitro indicate that chylomicron remnants and beta-VLDL interact specifically with the same remnant receptor. Hepatic uptake of 125I-labelled-alpha 2-macroglobulin in vivo, mediated equally by parenchymal and endothelial cells, is not decreased by preinjection of lactoferrin and no effect on the parenchymal-cell-mediated uptake is found. In vitro, alpha 2-macroglobulin and chylomicron remnants or beta-VLDL show no cross-competition. Culturing of parenchymal cells for 24-48 h leads to a decrease in the cell association of alpha 2-macroglobulin to 26% of the initial value, while the cell association of beta-VLDL with the remnant receptor is not influenced. It is concluded that beta-VLDL and chylomicron remnants are recognized by a specific remnant receptor on parenchymal liver cells, while uptake of alpha 2-macroglobulin by liver is carried out by a specific receptor system (presumably involving the LDL-receptor-related protein) which shows properties that are distinct from those of the remnant receptor.

Lactosylated low density lipoprotein: a potential carrier for the site-specific delivery of drugs to Kupffer cells.

Low density lipoprotein (LDL) is a spherical particle with a diameter of 22 nm. It consists of an apolipoprotein and a lipid moiety, in which a variety of lipophilic drugs and prodrugs can be incorporated. In the present study, lactose was coupled to the apolipoprotein of LDL by reductive amination (398 +/- 40 residues/LDL particle). After injection into rats, radioactively labeled lactosylated LDL was cleared rapidly from the plasma (half-life, less than 2 min). Ten minutes after injection, the liver contained about 90% of the dose, whereas only small amounts of radioactivity were found in other tissues. Preinjection of N-acetylgalactosamine completely blocked liver uptake, whereas N-acetylglucosamine was ineffective. This indicates that the hepatic recognition site is galactose specific. Subcellular fractionation of liver indicated that the recognition of lactosylated LDL is followed by internalization and degradation of the apolipoprotein in the lysosomes. In the liver, Kupffer cells are mainly responsible for uptake. At 10 min after injection, these cells contained a 70 and 7 times higher amount of lactosylated LDL per mg of cell protein than parenchymal and endothelial cells, respectively. After galactose-specific uptake in parenchymal cells was blocked with asialofetuin, the relative concentration in Kupffer cells was even higher. The hepatic uptake of the lipid moiety of lactosylated LDL, labeled with [3H]cholesteryl oleoyl ether, was identical to that of the 125I-labeled apolipoporotein, which indicates that the particle is taken up as a unit. Thus, lactosylated LDL is taken up rapidly and selectively by Kupffer cells, and it appears that it might be a very effective vehicle for the specific delivery of lipophilic drugs, e.g., immunomodulators, to these cells.