Biomedical subjects

R Lüllmann-Rauch

Publications and source records attributed to R Lüllmann-Rauch.

At least 37 records · Page 2Linked to original sources

PubMed1996

Phenotype of arylsulfatase A-deficient mice: relationship to human metachromatic leukodystrophy.

Metachromatic leukodystrophy is a lysosomal sphingolipid storage disorder caused by the deficiency of arylsulfatase A. The disease is characterized by progressive demyelination, causing various neurologic symptoms. Since no naturally occurring animal model of the disease is available, we have generated arylsulfatase A-deficient mice. Deficient animals store the sphingolipid cerebroside-3-sulfate in various neuronal and nonneuronal tissues. The storage pattern is comparable to that of affected humans, but gross defects of white matter were not observed up to the age of 2 years. A reduction of axonal cross-sectional area and an astrogliosis were observed in 1-year-old mice; activation of microglia started at 1 year and was generalized at 2 years. Purkinje cell dendrites show an altered morphology. In the acoustic ganglion numbers of neurons and myelinated fibers are severely decreased, which is accompanied by a loss of brainstem auditory-evoked potentials. Neurologic examination reveals significant impairment of neuromotor coordination.

Animals↗

PubMed1996

The antimalarials quinacrine and chloroquine induce weak lysosomal storage of sulphated glycosaminoglycans in cell culture and in vivo.

The antimalarial agents quinacrine and chloroquine are well known as potent inducers of lysosomal storage of polar lipids (lipidosis) in cell culture and in vivo. In previous experiments on cultured fibroblasts, chloroquine was shown to additionally cause weak lysosomal storage of sulphated glycosaminoglycans (GAGs) thus inducing mucopolysaccharidosis (MPS). In the present study, quinacrine was investigated for this ability, because we wished to know whether or not the acridine ring system in quinacrine would enhance the MPS-inducing potency as compared to chloroquine carrying an isoquinoline ring system. Tilorone (2,7-bis[2-(diethylamino)ethoxy]fluoren-9-one) known as a potent inducer of MPS served as reference compound. The compounds were compared at a concentration (3 microM) which did not enhance the secretion of the lysosomal enzyme beta-hexosaminidase (E.C. 3.2.1.52), since this would be an indication of unspecific drug effects upon the endosomal/lysosomal compartments of the cell. Additionally the liver of quinacrine- and chloroquine-treated rats was examined with the question whether the lysosomal GAG storage induced by either drug in cell culture had an equivalent in intact organisms. Both, in cell culture and in vivo, quinacrine was found to be a more potent inducer of lysosomal GAG storage than was chloroquine. The results suggest that the acridine ring system favours this drug side effect as compared with the bicyclic isoquinoline ring system. On the other hand, quinacrine was significantly less potent than tilorone and the Symmetrically substituted acridine derivative 3,6-bis[2-(diethylamino)ethoxy]acridine investigated previously. This suggests that the asymmetric structure of the quinacrine molecule reduces the potency as compared to the symmetrically substituted bisbasic compounds with planary tricyclic ring systems such as tilorone and congeners.

Animals↗

PubMed1996

Tilorone-induced lysosomal lesions: the bisbasic character of the drug is essential for its high potency to cause storage of sulphated glycosaminoglycans.

The immunomodulatory agent tilorone -2,7-bis-[2-(diethyl-amino)ethoxy]fluoren-9-one- and congeners are potent inducers of lysosomal storage of sulphated glycosaminoglycans (GAGs) in animals and cultured fibroblasts of animals and man. All potent inducers of GAG storage hitherto described are bisbasic polycyclic aromatic compounds. They are accumulated in lysosomes and disturb the degradation of GAGs, mainly dermatan sulphate. It has been proposed that the drugs cross-link the polyanionic GAG chains giving rise to undergradable drug-GAG complexes. This hypothesis implies that the bisbasic character of the drug molecules is essential for the side effect in question. In the present study, this was tested by comparing tilorone and its monobasic derivative (MT) with respect to (i) induction of GAG storage in cultured bovine corneal fibroblasts and (ii) physicochemical interactions with GAGs in vitro. The intralysosomal concentration of MT achieved after 1-3 days was of the same order of magnitude as previously shown for tilorone. Nevertheless, under conditions that did not enhance the secretion of a lysosomal enzyme (beta-hexosaminidase, EC 3.2.1.52), the ability of MT to cause storage of [35S]GAGs was significantly lower than that of tilorone. Morphological observations showed that MT was much more potent in causing lysosomal storage of polar lipids than of GAGs. CD spectroscopy with tilorone revealed that the presence of GAGs caused the primarily achiral drug molecules to display CD. This suggested a helical orientation of the tilorone molecules within GAG-drug complexes, and short intermolecular distances which allowed electronic coupling of the aromatic ring systems of adjacent drug molecules. In contrast, MT failed to display any induced optical activity, indicating the absence of highly ordered GAG-drug complexes. In conclusion, the present results show that the substitution of the planar aromatic ring system with two basic side chains is essential for the high potency of tilorone in inducing lysosomal GAG storage. This is paralleled by, and presumably causally related to, strong physicochemical interactions with GAGs.

Adjuvants, Immunologic↗

PubMed1996

Lysosomal storage of sulfated glycosaminoglycans induced by two bis-aminomethyl anthrachinones.

Several immunomomodulatory drugs, all of them symmetrically substituted dicationic amphiphilic compounds, are known to cause lysosomal storage of sulfated glycosaminoglycans (GAGs) in intact animals and cultured fibroblasts. The storage is due to impaired GAG degradation. The standard compound is tilorone (2,7-bis[2-(diethylamino)ethoxy]fluoren-9-one). In the present study two bis-aminomethyl anthrachinones were examined for their ability to induce lysosomal GAG storage in cultured bovine corneal fibroblasts. For reference, a bis-aminoethoxy-anthrachinone compound (RMI-10.024) was included, which is known to be a potent inducer of lysosomal GAG storage. The present morphological, radiochemical, and biochemical results show that the bis-aminomethyl anthrachinone compounds investigated cause lysosomal storage of GAGs, although with significantly lower potencies than the bis-aminoethoxy anthrachinone. Dermatan sulfate contributed approximately 90% to the drug-induced increment of intracellular GAGs. The present results suggest that the length of the side chains, i.e., the distance between the aromatic ring system and the protonizable nitrogen of the side chains, and the position of the side chains relative to the aromatic ring system are important molecular features influencing the potency of inducing lysosomal GAG storage.

Animals↗

PubMed1996

Drug-induced lysosomal storage of sulphated glycosaminoglycans.

1. Certain compounds (e.g., the immunomodulator tilorone and congeners) are able to induce lysosomal storage of sulphated glycosaminoglycans (GAG), thus, producing cytological and biochemical alterations reminiscent of the inherited mucopolysaccharidoses. The drug-induced GAG storage has been studied in cultured fibroblasts of several species and in rats, and it is likely to occur also in humans. 2. The cytological hallmarks of GAG storage are enlarged lysosomes congested with material that is intensely stained by cationic dyes. With respect to fixation techniques, one has to keep in mind that the GAGs are highly water-soluble and are leached during conventional fixation and tissue processing. Biochemically, the elevation of GAG contents in tissues and cultured fibroblasts is due to storage of dermatan sulphate, predominantly. 3. The molecular structure of the potent inducers of GAG storage is characterized by a planar tricyclic aromatic ring system that is symmetrically substituted with two side chains of 4-5 sigma bond length, each carrying a protonizable nitrogen atom. The lysosomal storage of GAG is accompanied by lysosomal accumulation of the inducing drug, with the molar ratio of drug to GAG-disaccharide unit amounting to > 1:1. The reversibility of GAG storage is rather slow. 4. The pathogenic mechanisms underlying the drug side effects are discussed and the following hypothesis is put forward: The compounds in question are lysosomotropic weak bases. They get trapped in the acidic lysosomes and accumulate highly there. Physicochemical data suggest that the drugs form complexes with the sulphated GAGs, particularly with dermatan sulphate: The positively charged nitrogen atoms of the drug side chains interact with the negative charges of sulphate and carboxy groups of the GAGs, thereby crosslinking at least two GAG helices. Moreover, the interlinking drug molecules form parallel stacks resulting from interaction of the aromatic pi-electrons of the planar ring systems. This further stabilizes the complexes. The GAGs within the complexes are thought to be resistant to the degrading lysosomal enzymes. 5. Drug-induced GAG storage has not been directly demonstrated in man. Yet, clinical reports on keratopathy and basophilic cytoplasmic inclusions in blood lymphocytes of tilorone-treated patients suggest that this drug side effect may also occur in man.

Adjuvants, Immunologic↗

PubMed1996

Lysosomal storage of sulphated glycosaminoglycans induced by dicationic amphiphilic drug molecules: significance of the central planar ring system.

The immunomodulatory drug tilorone (2,7-bis[2-(diethylamino)ethoxy]fluoren-9-one) and several congeners are known to disturb the lysosomal degradation of sulphated glycosaminoglycans and thereby induce lysosomal storage of glycosaminoglycans in cultured cells and intact organisms. The molecules of tilorone and congeners consist of a planar aromatic ring system symmetrically substituted with two aliphatic side chains each carrying a protonizable nitrogen. In a previous study it was proposed that non-degradable glycosaminoglycan-drug complexes are formed by electrostatic interactions and that additionally intermolecular interactions between the drug molecules due to electronic coupling of their central planar ring system are important for formation and stabilization of the glycosaminoglycan-drug complexes and thus for the drug side effect in question. The significance of the central planar ring system was tested in the present study by comparing tilorone and the compound bis(beta-diethylamino-ethylether)hexestrol (DH) with respect to their potencies to cause lysosomal glycosaminoglycan storage in cultured bovine corneal fibroblasts. DH has the same side chains as tilorone, but its central apolar moiety lacks planarity. At a concentration (1.75 muM) which did not cause enhanced secretion of the lysosomal enzyme beta-hexosaminidase (E.C. 3.2.1.52), DH was significantly less potent than tilorone in causing storage of [35S]glycosaminoglycans. This is taken as support of the hypothesis that the planar tricyclic ring system is essential for the high potency of tilorone and its congeners to exert this adverse action.

Adjuvants, Immunologic↗

PubMed1995

Tilorone-induced lysosomal storage of sulphated glycosaminoglycans can be separated from tilorone-induced enhancement of lysosomal enzyme secretion.

This investigation deals with a drug side-effect. The immunomodulatory drug tilorone (2,7-bis[2-(diethylamino)ethoxy]fluoren-9-one) and congeners induce lysosomal storage of sulphated glycosaminoglycans (GAGs) in animals and in cultured cells. At high tilorone concentrations, GAG storage in cultured fibroblasts was previously reported to be accompanied, and presumably caused by, disturbance of intracellular targeting of lysosomal enzyme precursors, which leads to enhanced secretion and thus loss of lysosomal enzymes. The purpose of the present study was to examine whether the GAG storage induced in cultured bovine fibroblasts by low tilorone concentrations is also accompanied by enhanced lysosomal enzyme release. Enhanced secretion of beta-hexosaminidase (EC 3.2.1.52) was taken as indicating the intracellular mistargeting of lysosomal enzyme precursors. Dose-response curves were established for (a) the intracellular accumulation of 35S-GAGs and (b) the release of beta-hexosaminidase after exposure (72 hr) to tilorone (1-35 microM). For positive controls, the classical lysosomotropic agents NH4Cl (1-30 mM) and chloroquine (1-60 microM) were used. With NH4Cl, 35S-GAG storage was accompanied by enhanced enzyme release throughout the concentration range (EC50 at 3.3 mM for either effect). With chloroquine, low concentrations (< or = 5 microM) caused a small increase in 35S-GAG accumulation without abnormal enzyme secretion; at higher concentrations both drug effects were produced (EC50 around 15 microM for either effect). With tilorone, low concentrations (< or = 5 microM) caused marked 35S-GAG accumulation without enhancement of enzyme release. The EC50 for tilorone-induced 35S-GAG storage was 3 microM, as opposed to 15 microM for enzyme release. The results indicate that GAG storage induced by low concentrations of tilorone is due to mechanisms other than mistargeting and loss of lysosomal enzymes. On the basis of previous results it may be hypothesized that tilorone and other symmetrically substituted dicationic compounds form complexes with the polyanionic GAG chains and thereby impair their enzymic degradation.

Ammonium Chloride↗

PubMed1994

Drug-induced intralysosomal storage of sulfated glycosaminoglycans (GAGs): a methodical pitfall occurring with acridine derivatives.

The present communication deals with an adverse drug action which is exerted by a series of dicationic amphiphilic compounds such as the immunomodulatory drug tilorone and congeners. The drugs induce lysosomal storage of sulfated glycosaminoglycans (GAGs) in intact organisms and in cultured cells by impairing the lysosomal GAG degradation. This impairment was proposed to be due to the formation of non-degradable GAG-drug complexes. GAGs are highly water-soluble and not preservable by aldehyde fixatives. Therefore, usually the lysosomes appear optically empty in histological preparations, unless the fixative is supplemented with a GAG-precipitating agent. When acridine derivatives were used for the induction of GAG-storage, the lysosomal storage material displayed unexpected and unsystematic variability with regard to its preservability and ultrastructure. In the present study, evidence is presented that the acridine derivatives (a) remain bound to the stored GAGs for some time after glutaraldehyde fixation; and (b) they precipitate GAGs in vitro. Thus, apart from their unwanted action in the living cell, i.e., disturbing lysosomal GAG-degradation, the drugs function as precipitants and "fixatives" for the intralysosomal GAGs. The uncontrolled persistence of the drugs after tissue fixation leads to variable degree of GAG-preservation and thus to unpredictable variability of the ultrastructure of the storage lysosomes. If this pitfall is not realized, the resulting inconsistencies may rise confusion among toxicologic pathologists who deal with drug-induced lysosomal storage disorders.

Acridines↗

PubMed1994

Experimentally induced lipidosis in uterine and vaginal epithelium of rats.

The purpose of this study was to investigate the effects of two lipidosis-inducing drugs (the anorectic drug chlorphentermine and the tricyclic antidepressant-imipramine) upon the estrous cycle of rats and upon the morphology of the vaginal and uterine epithelia. After two weeks of continuous administration of high daily drug doses, the estrous cycle became stagnant. Ultrastructurally, the vaginal and uterine epithelia contained storage lysosomes which were filled with undigested polar lipids appearing as multilamellated material. The uterine luminal epithelium was most severely affected. The estrous cycle was abolished also by treatment with the anorexigenic drug phentermine, although this compound does not cause lipidosis. Therefore, the cessation of the estrous cycle cannot be attributed to the lipidosis as induced by chlorphentermine and imipramine; probably it is a consequence of the main actions of these psychotropic drugs. The biological basis for the exceedingly severe lipidosis in the uterine luminal epithelium is suggested to be the heavy load of polar lipids physiologically delivered to the lysosomal apparatus as long as the cycle-dependent apoptotic and autophagic processes were going on during the early period of drug treatment.

Animals↗

PubMed1994

The structure and vascularization of the biceps brachii long head tendon.

In the present study we examined the structure and the blood supply of the long biceps tendon as well as the surface of the intertubercular sulcus, using tissue samples from children and adults. The applied methods were light and electron microscopy, immunohistochemistry, and arterial injection techniques. The tendon represents a sliding tendon with the intertubercular sulcus and humeral head as hypomochlion. The parts facing the humerus show some ultrastructural features of fibrous cartilage, the ovoid chondrocyte-like cells of the tendon lying within felt-like matrix. In the opposite part adjacent to the capsule, the tendon resembles a traction tendon. The intertubercular sulcus is covered by fibrous cartilage. The tendon is supplied with arteries from three different sources. The density of intratendinous vessels in the traction zone is comparable to that of other tendons, while in the sliding zone it is markably decreased. The immediate vicinity of the sliding surface is avascular. Our findings show that the long biceps tendon is structurally adapted to both its functions as sliding and traction tendon. The blood supply seems to be related to the metabolic requirements of the different parts of the tendon.

Adolescent↗

PubMed1993

Drug-induced lysosomal storage of sulfated glycosaminoglycans. Studies on the underlying structure-activity relationships.

Some immunomodulatory drugs have previously been shown to induce lysosomal storage of sulfated glycosaminoglycans (sGAG) in intact organisms and cultured cells. These compounds consist of a planary aromatic ring system and two symmetric side chains each carrying a protonizable nitrogen. The purpose of this study was to test a larger collection of such compounds for their potencies to induce lysosomal storage of sGAG in cultured fibroblasts of rat cornea. The cells were exposed (72 h) to various compounds differing with respect to the aromatic ring system or the side chains. Lysosomal sGAG-storage was demonstrated by selective cytochemical staining with cuprolinic blue. The threshold concentration, i.e., the concentration necessary to induce cuprolinic blue-positive cytoplasmic inclusions in at least 1% of the cells, was determined for each compound. The threshold concentrations were distributed over a range of 0.3-30 microM. It should be emphasized that the threshold concentration of a given compound is not a constant, but depends on the volume of cell culture medium per surface area of cell monolayer, since the lysosomal accumulation lowers the initial drug concentration in the medium. If the ratio of medium volume:cell monolayer surface is increased as compared with standard cell culture conditions, the threshold concentration will be lowered. The compounds were ranked according to their threshold concentrations as determined under standard conditions. The following conclusions can be drawn from the ranking: the type of the central aromatic ring system and the distance between the ring system and the protonizable nitrogen atoms of the side chains influence the potency to induce lysosomal sGAG-storage. Regarding the ring system, the potency decreases as follows: acridine approximately anthrachinone > fenfluorenone approximately fenfluorene > xanthenone; xanthene > dibenzofuran approximately dibenzothiophene. In intact organisms, these structure-activity relationships may be superimposed by drug metabolism and pharmacokinetic factors.

Adjuvants, Immunologic↗

PubMed1992

Lysosomal storage of sulfated glycosaminoglycans in cultured fibroblasts exposed to immunostimulatory acridine derivatives.

The purpose of the present cytological and radiochemical study was to investigate whether the immunomodulatory agent 3,6-bis[2-(diethylamino)ethoxy]acridine (CL-90.100) and three congeners induce lysosomal storage of sulfated glycosaminoglycans (sGAG) in cultured rat corneal fibroblasts. The reason for asking this question was as follows: The four acridine derivatives have molecular similarities with the dicationic amphiphilic compound tilorone, which has previously been shown to cause sGAG storage in cultured cells and in intact rats. The cells were exposed to the drugs for 72 hr. Tilorone served as reference. All acridine derivatives caused cytological alterations which, on the basis of the cytochemical results, were indicative of lysosomal sGAG storage. The threshold concentrations ranged from 0.3 to 0.7 microM. Radiochemical experiments showed that CL-90.100 up to 10 microM induced [35S]GAG storage in a dose-dependent manner, with an EC50 of 2 microM. Concentrations above 10 microM were cytotoxic. Experiments with equimolar concentrations (3 microM) demonstrated that three of the acridine derivatives were more potent and one was less potent than tilorone. Additionally, CL-90.100 was tested on bovine corneal fibroblasts, with cytochemical and radiochemical results similar to those in rat cells. The present findings show that (a) the four acridine derivatives induce lysosomal sGAG storage; (b) the acridine ring, compared with the fenfluorenone ring (tilorone), enhances this potency; and (c) the substituents at the nitrogens can have some influence on the potency to induce sGAG storage.

Acridines↗

PubMed1992

Induction of mucopolysaccharidosis in rats by treatment with immunostimulatory acridine derivatives.

In the accompanying paper, four dibasic acridine derivatives were reported to induce lysosomal storage of sulfated glycosaminoglycans (sGAG), i.e., mucopolysaccharidosis, in cultured fibroblast (Handrock et al. Toxicol. Appl. Pharmacol. 114, 1992). The purpose of the present morphological and biochemical investigation was to examine whether two representatives of the acridine derivatives, namely 3,6-bis[2-(diethylamino)ethoxy]-acridine and the piperidino analogue, induce mucopolysaccharidosis in intact organisms. Rats were orally treated with 60-80 mg/kg up to 22 weeks. Morphological examination of liver, spleen, and blood lymphocytes yielded cytochemical evidence of mucopolysaccharidosis. Biochemically, up to a 48-fold increase of the urinary excretion of sGAG was found. In the liver and spleen of chronically treated rats, the sGAG contents were elevated by factors up to 56 and 23, respectively. Heparan sulfate and dermatan sulfate contributed most to the total increase of sGAG; chondroitin sulfate was stored to a minor degree. For one compound, the tissue concentrations were determined. It was found that the drug was accumulated in the tissues. Due to their fluorescent properties, the drugs could be detected by fluorescence microscopy to be present in high concentrations within the sGAG-storing lysosomes. On the basis of these observations and of the biochemical data it appears justified to assume a ratio of at least one drug molecule per disaccharide unit of the sGAG to be present in the lysosomes. It is proposed that this leads to the formation of sGAG-drug complexes in the lysosomes. Such complexes may be indigestible substrates for the lysosomal enzymes, thus leading to mucopolysaccharidosis. For toxicologic practice, the cytochemical examination of lymphocytes is recommended as a simple measure for early detection and monitoring of this adverse drug effect.

Acridines↗

PubMed1992

Osteopenia in rats with drug-induced mucopolysaccharidosis.

The immunostimulatory drug tilorone (CAS 27591-97-5) induces generalized lysosomal storage of sulfated glycosaminoglycans, i.e., mucopolysaccharidosis (MPS) in rats. Since inherited MPS of man is often associated with skeletal lesions the present study was performed to investigate whether the tilorone-induced MPS is also accompanied by bone alterations. The answer is yes. Rats (initial age 4 weeks) were orally treated with tilorone (60-80 mg/kg; 6-25 weeks). The proximal tibial metaphysis was examined by radiography and by light and electron microscopy. The tibiae of drug-treated rats remained smaller than those of pair-fed control rats. The primary bone trabecules in drug-treated rats became increasingly shorter, and the cortical bone became thinner. The general organization of the cartilaginous growth plate and the zones of vascular invasion and primary trabecule formation appeared similar as in control rats. Increased numbers of active osteoclasts were found at the free ends of the primary trabecules. Ultrastructurally, MPS-like alterations were observed in all types of bone cells. The osteopenia was partly reversible during recovery periods of more than 6 months after discontinuance of drug treatment. At present, the causal relationship between drug-induced MPS and osteopenia, as well as the mechanisms responsible for osteopenia are unknown. It is suggested that the principal factors are stimulation of osteoclasts and retardation, though not profound distortion, of the events involved in enchondral ossification.

Animals↗

PubMed1991

Acridine Orange, a precipitant for sulfated glycosaminoglycans, causes mucopolysaccharidosis in cultured fibroblasts.

The purpose of the present investigation was to examine whether or not a di-cationic amphiphilic compound that is known (1) to be accumulated in lysosomes and (2) to form insoluble complexes with sulfated glycosaminoglycans (sGAG) in vitro, is able to interfere with the lysosomal degradation of sGAG, thus causing mucopolysaccharidosis (MPS) in cultured cells. Acridine Orange (AO) was chosen for this study since it is known to meet the above requirements. Cultured fibroblasts from rat cornea were exposed to AO (0.7 microM to 30 microM) for 72 h; tilorone served as reference compound. AO (1.75 microM to 10 microM) caused MPS in a concentration-dependent manner, higher concentrations were cytotoxic. MPS was demonstrated by cytochemical staining with cuprolinic blue and by measuring the intracellular accumulation of [35S]-GAG. The sGAG-complexing properties of AO were demonstrated by using it as a fixative for the intralysosomal sGAG accumulated in tilorone-treated cells. The present findings give support to the working hypothesis that the MPS induced by di-cationic amphiphilic drugs is due to the formation of insoluble sGAG-drug complexes, with the result that the sGAG become resistant to lysosomal degradation.

Acridine Orange↗

PubMed1991

Drug-induced lysosomal storage of sulfated glycosaminoglycans in cultured bovine and human fibroblasts.

Several di-cationic amphiphilic compounds are known to cause lysosomal accumulation of sulfated glycosaminoglycans (sGAG) in intact rats and in cultured rat fibroblasts. The purpose of the present investigation was to examine whether this drug side effect also occurs in bovine and human cells. Cultured fibroblasts from both species were exposed to tilorone (3 microM and 5 microM) for 72 h; lysosomal sGAG-storage was demonstrated by cytochemical staining with cuprolinic blue and by measuring the intracellular accumulation of [35S]-GAG. The cytological alterations as well as the radiochemical results in both species were in good agreement with previous data from rat fibroblasts. The present findings indicate that the drug-induced lysosomal storage of sGAG is a species-independent phenomenon. Thus, cultured bovine and human fibroblasts are a suitable model for further studies concerning the as yet unknown molecular mechanisms underlying this adverse drug action.

Animals↗

PubMed1990

Cultured corneal fibroblasts as a model system for the demonstration of drug-induced mucopolysaccharidosis.

The purpose of the present investigation was to establish a cell culture system suitable for demonstrating the drug-induced lysosomal storage of sulfated glycosaminoglycans (GAGs). This is a drug side-effect which was previously studied in animals treated with the di-cationic amphiphilic compound tilorone and congeners, and which is likely to occur in humans, too. Cultured corneal fibroblasts of rats were exposed to tilorone for 72 h. They developed histochemical and cytochemical alterations indicative of mucopolysaccharidosis and resembling those occurring in vivo. The threshold drug concentration was found to be below 0.7 microM. The reversibility of the lysosomal GAG storage was low. An increase in the drug concentration to 10 microM produced additional unspecific lysosomal alterations, while the mucopolysaccharidosis-like lesions became less prominent. Concentrations of 40 microM and 80 microM caused unspecific cytoplasmic vacuolation and cell death, respectively. The present model system appears suitable for screening investigations of newly developed drugs with respect to their mucopolysaccharidosis-inducing potential and for investigating the structure-activity relationships underlying this adverse drug effect. Care should be taken not to use too high drug concentrations which cause unspecific lysosomal lesions.

Animals↗

PubMed1990

Human accumulation potential of xenobiotics: potential of catamphiphilic drugs to promote their accumulation via inducing lipidosis or mucopolysaccharidosis.

1. Drug accumulation without a concomitant elevation of blood level may occur if the capacity of the tissue to bind drug increases during chronic treatment. 2. This special type of accumulation is found with cationic-amphiphilic drugs, which induce the formation of lysosomal inclusion bodies containing undergraded lipids or mucopolysaccharides (drug-induced lipidosis or mucopolysaccharidosis, respectively); the stored material provides the additional binding sites for the drug. 3. Factors determining the potential for inducing lipidosis or mucopolysaccharidosis are: (a) affinity of the drugs to phospholipid layers (governed by hydrophobicity) or mucopolysaccharides (drug-induced lipidosis or mucopolysaccharidosis, respectively); the free intra-lysosomal concentration, which is elevated compared with the blood level due to lysosomal trapping (especially with dicationic drugs); (c) the therapeutically required drug concentration in the blood: the therapeutic concentrations are high with drugs that do not act via binding to specific high-affinity receptors.

Glycosaminoglycans↗