Efficacy of multidisciplinary approach in the treatment of two cases of nonclassical infantile glycogenosis type II

Glycogenosis type II (GSD II) is a lysosomal storage disorder due to acid alpha-glucosidase deficiency. We report the results of a clinical multidisciplinary approach in two cases of nonclassical infantile GSD II. The patients received a high-protein diet by percutaneous enteral gastrostomy (PEG), mechanical ventilatory support by tracheostomy and a physiotherapy programme. After 12 months of treatment, the patients showed significant improvement in muscular strength, nutritional state and respiratory function. Electrocardiography (ECG) and echocardiography improved in both patients. They maintained good clinical conditions for a period of 18 and 20 months, respectively; thereafter they presented with an elevated and persistent fever that was not correlated to a septic status and was not responsive to any antipyretic treatment. They deteriorated progressively and died. This study shows how a multidisciplinary approach may be useful to improve, even if temporarily, the clinical course of nonclassical infantile GSD II.

A3 adenosine receptors in human astrocytoma cells: agonist-mediated desensitization, internalization, and down-regulation

A(3) adenosine receptor activation has been previously demonstrated to result in both neuroprotective and neurodegenerative effects, depending upon specific pathophysiological conditions. This dual effect may depend on receptor regulation mechanisms that are able to change receptor availability and/or function. In the present study, we investigated desensitization, internalization, and down-regulation of native A(3) adenosine receptors in human astrocytoma cells after exposure to the agonist 2-chloro-N6-(3-iodobenzyl)-N-methyl-5'-carbamoyladenosine (Cl-IBMECA). Cl-IBMECA induced a concentration-dependent inhibition of adenylyl cyclase activity with an EC(50) value of 2.9 +/- 0.1 nM. The effect was suggested to be mediated by A(3) adenosine receptor subtype by the use of selective adenosine receptor antagonists. Cell treatment with pertussis toxin abolished Cl-IBMECA-mediated inhibition of adenylyl cyclase activity, evidencing an A(3) receptor coupling to inhibitory G protein. Short-term exposure to the agonist Cl-IBMECA (100 nM) caused rapid receptor desensitization, within 15 min. Agonist-induced desensitization was accompanied by receptor internalization: A(3) adenosine receptor internalized with rapid kinetics, within 30 min, after cell exposure to 100 nM Cl-IBMECA. The localization of A(3) adenosine receptors on the plasma membrane and in intracellular compartments was directly revealed by immunogold electron microscopy. After desensitization, the removal of agonist led to the restoration of A(3) adenosine receptor functioning through receptor recycling to the cell surface within 120 min. Prolonged agonist exposure (1-24 h) resulted in a marked down-regulation of A(3) adenosine receptors that reached 21.9 +/- 2.88% of control value after 24 h. After down-regulation, the recovery of receptor functioning was slow (24 h) and associated with the restoration of receptor levels close to control values. In conclusion, our results demonstrated that A(3) receptors, in astrocytoma cells, are regulated after short- and long-term agonist exposure.

Bone complications in children with Gaucher disease

For paediatric patients with Gaucher disease, enzyme replacement therapy (ERT) has the potential to prevent the development of serious, irreversible skeletal complications. Analysis of skeletal data for paediatric patients receiving ERT must take into account the pubertal growth spurt and developmental changes in bone marrow composition. In a study conducted at the Burlo Garofolo Institute in Trieste, Italy, 10 paediatric patients have received ERT, and data are available for 3-9 years of follow-up. ERT was associated with a significant increase in the mean lumbar bone mineral density (BMD) Z score after 2 years of treatment (p=0.003). Skeletal growth rates increased among patients exhibiting growth delays. At the Gaucher Disease Treatment Center in Cincinnati, OH, USA, a total of 11 paediatric patients have been followed for 2 years or more of ERT. Of these 11 patients, 6 have demonstrated significant increases in lumbar BMD after 2 years of ERT; these patients tended to have lower BMD Z scores at the start of ERT. At the Children's Hospital of the Johannes-Gutenberg University in Mainz, Germany, 7 children with type 1 Gaucher disease presented with reduced BMD in the distal ulna, and after 18-24 months of ERT, these patients demonstrated increases in BMD at this site. The patients exhibiting growth retardation experienced growth acceleration during treatment. These studies suggest that ERT improves BMD and growth rates in paediatric patients with Gaucher disease. ERT in paediatric patients may have the potential to prevent serious skeletal complications such as fractures and vertebral compression later in life.

Two novel mutations of the human Δ7-sterol reductase (DHCR7) gene in children with Smith–Lemli–Opitz syndrome

We analyzed seven unrelated children with the Smith-Lemli-Opitz syndrome (SLOS) for mutations in the delta7-sterol reductase gene by using SSCP and direct sequencing. We identified two novel mutations (V330M and R363C) in the DHCR7 gene. Reported mutations found in this study were T93M (3/14 alleles), E448K (2/14), and W151X, G244R, P329L, and R446Q (each found in one allele). The so-called common IVS8-1 G --> C was found in three alleles, confirming its relative rarity among Italian SLOS families. By using a scoring system, clinical severity did not seem to correlate with 7DHC levels and type of mutation. Expanding the spectrum of mutations in SLOS, our study does not support direct genotype-phenotype correlation.

Importance of a small N-terminal region in mammalian peptide transporters for substrate affinity and function

The two closely related, proton-coupled, electrogenic mammalian peptide transporters PEPT1 and PEPT2 differ substantially in substrate affinity and mode of function. The intestinal carrier PEPT1 has a lower affinity for most substrates than the isoform PEPT2 that is expressed in kidney, lung, brain and other tissues. A previous analysis of PEPT1-PEPT2 chimeras has suggested that the N-terminal half of the carrier proteins is important for substrate affinity. We constructed and analyzed new PEPT1-PEPT2 chimeras for identifying smaller segments within the N-terminal region of the transporter proteins that contribute to the kinetic properties. The first 59 or 91 amino-acid residues of PEPT1 were used to replace the corresponding region in PEPT2 leading to the chimeras CH3 and CH4, which could be analyzed when expressed in Xenopus laevis oocytes. Substrate affinities of both chimeras for the zwitterionic substrate D-Phe-Ala ranged between those that are characteristic for either PEPT1 or PEPT2, but when charged dipeptide substrates were employed, both chimeras possessed PEPT1-like affinities. The chimera CH3 carrying the N-terminal 59 amino-acid residues of PEPT1 exhibited a PEPT2-like phenotype with respect to pHout-dependency as well as to the current-voltage relationship of inward currents. In the chimera CH4 possessing the 91 amino-terminal residues of PEPT1, a pronounced alteration in the pHout-dependence was observed, with highest transport rates occurring at pH values as low as pH 4.0. Based on this analysis, we propose that the two identified aminoterminal regions in mammalian peptide carriers play an important role in determining the substrate affinity and also other characteristic features of the two transporter subtypes.

Glycolipid analysis of different tissues and cerebrospinal fluid in type II Gaucher disease

The lipid composition or the liver, spleen, brain, cerebellum and cerebrospinal fluid of a Gaucher disease type II patient who died at the age of 5 months was examined. The glycolipid analysis demonstrated a marked increase of total amounts not only in the peripheral tissues but also in the brain cerebellum and cerebrospinal fluid, with a prevalence of glucosylceramide. A reduction in gangliosides was observed in all the analysed tissues with a relative increase of GD3 in the nervous tissue. The fatty acid composition of glucosylceramide showed a prevalence of stearic acid in the central nervous system, while in the peripheral tissues palmitic acid was prevalent. This result suggests a different origin of the glucosylceramide stored in different tissues. The generalized reduction of gangliosides and their modified distribution together with the central nervous system GD3 increment represent a new observation. These data could be useful in the effort to clarify the pathophysiological mechanism of brain damage in neuronopathic Gaucher disease.

7-Nitrobenzofurazan (NBD) derivatives of 5'-N-ethylcarboxamidoadenosine (NECA) as new fluorescent probes for human A(3) adenosine receptors

New fluorescent ligands for adenosine receptors (ARs), obtained by the insertion, in the N(6) position of NECA, of NBD-moieties with linear alkyl spacers of increasing length, proved to possess a high affinity and selectivity for the A(3) subtype expressed in CHO cells. In fluorescence microscopy assays, compound 2d, the most active and selective for human A(3)-AR, permitted visualization and localization of this human receptor subtype, showing its potential suitability for internalization and trafficking studies in living cells.

[Giacomo Andrea Diacomini, the medical systems and the origins of experimental pharmacology]

Giacomo Andrea Ciacomini was Professor of Physiology, Pathology and General Therapeutics in the University of Padua (1824-1849); follower of systematic medicine, he followed vitalistic theories. For him diagnosis-identification of diseases and therapy are closely related and diseases are due to an excess or a loss of stimulations. About quinine, generally administered in fevers at high doses as a tonic-stimulant drug, Giacomini believed that it has a depressant activity, an action verified by him on rabbits, an early example of exerimental pharmacology in Italy (1840). Thus, Giacomini performed empirical studies, and the real differences between systematic and scientific medicine are in the different approach to the relationship between empirical observations and theoretical hypotheses.

2-Arylpyrazolo[1,5-a]pyrimidin-3-yl acetamides. New potent and selective peripheral benzodiazepine receptor ligands

A new class of N,N-diethyl-(2-arylpyrazolo[1,5-a]pyrimidin-3-yl)acetamides (3f-y), as azaisosters of Alpidem, was prepared following a novel synthetic method and their affinities for both the peripheral (PBR) and the central (CBR) benzodiazepine receptors were evaluated. Binding assays were carried out using both [3H]PK 11195 and [3H]Ro 5-4864 as radioligands for PBR, whereas [3H]Ro 15-1788 was used for CBR, in rat kidney and rat cortex, respectively. The tested compounds exhibited a broad range of binding affinities from as low as 0.76 nM to inactivity and most of them proved to be high selective ligands for PBR. The preliminary SAR studies suggested some of the structural features required for high affinity and selectivity; particularly the substituents on the pyrimidine moiety seemed to play an important role in PBR versus CBR selectivity. A subset of the highest affinity compounds was also tested for their ability to stimulate steroid biosynthesis in C6 glioma rat cells and some of these were found to increase pregnenolone formation with potency similar to Ro 5-4864 and PK 11195.

Synthesis and biological data of 4-amino-1-(2-chloro-2-phenylethyl)-1H-pyrazolo[3,4-b]pyridine-5-carboxylic acid ethyl esters, a new series of A1-adenosine receptor (A1AR) ligands

The synthesis of a new family of A1-adenosine receptor (A1AR) ligands 3a-n has been performed in a straightforward way. Affinity data at A1AR, A2AAR and A3AR in bovine membranes show that these new compounds bind the A1AR in a selective way over A2AAR and A3AR and one of them (3j) presents a very high affinity, probably due to the phenethylamine substituent at C-4.

Intractable fever and cortical neuronal glycogen storage in glycogenosis type 2

Glycogenosis type 2 is an autosomal recessive glycogen storage disorder caused by deficiency of lysosomal acid alpha-glucosidase. Different phenotypes are recognized. The authors describe two children affected by the late infantile form; both presented terminal hyperthermia not caused by infections. Autopsy performed in one case showed diffuse glycogen storage in the CNS neurons. In light of current interest in enzyme replacement therapy, this finding casts some doubt on how effective enzyme replacement therapy will be unless it can be targeted directly into the CNS.

Novel N-(arylalkyl)indol-3-ylglyoxylylamides targeted as ligands of the benzodiazepine receptor: synthesis, biological evaluation, and molecular modeling analysis of the structure-activity relationships

A series of N-(arylalkyl)indol-3-ylglyoxylylamides (4-8) was synthesized as ligands of the benzodiazepine receptor (BzR) and tested for their ability to displace [(3)H]flumazenil from bovine brain membranes. The new compounds, bearing a branched (4) or a geometrically constrained benzyl/phenylethyl amide side chain (5-8), represent the continuation of our research on N-benzylindol-3-ylglyoxylylamides 1 (Da Settimo et al., 1996), N'-phenylindol-3-ylglyoxylohydrazides 2 (Da Settimo et al., 1998), and N-(indol-3-ylglyoxylyl)alanine derivatives 3 (Primofiore et al., 1989). A few indoles belonging to the previously investigated benzylamides 1 and phenylhydrazides 2 were synthesized and tested to enrich the SARs in these two series. The affinities and the GABA ratios of selected compounds for clonal mammalian alpha(1)beta(2)gamma(2), alpha(3)beta(2)gamma(2), and alpha(5)beta(3)gamma(2) BzR subtypes were also determined. It was hypothesized that the reduced flexibility of indoles 4-8 would both facilitate the mapping of the BzR binding cleft and increase the chances of conferring selectivity for the considered receptor subtypes. In the series of indoles 4, the introduction of a methyl group on the benzylic carbon with the R configuration improved affinity of the 5-substituted (5-Cl and 5-NO(2)) derivatives, whereas it was detrimental for their 5-unsubtituted (5-H) counterparts. All S enantiomers were less potent than the R ones. Replacement of the methyl with hydrophilic substituents on the benzylic carbon lowered affinity. The isoindolinylamide side chain was tolerated if the 5-position was unsubstituted (K(i) of 5a = 123 nM), otherwise affinity was abolished (5b, c). All the 2-indanylamides 6 and (S)-1-indanylamides 8 were devoid of any appreciable affinity. The 5-Cl and 5-NO(2) (R)-1-indanylamides 7b (K(i) 80 nM) and 7c (K(i) 28 nM) were the most potent among the indoles 5-8 geometrically constrained about the side chain. The 5-H (R)-1-indanylamide 7a displayed a lower affinity (K(i) 675 nM). The SARs developed from the new compounds, together with those collected from our previous studies, confirmed the hypothesis of different binding modes for 5-substituted and 5-unsubstituted indoles, suggesting that the shape of the lipophilic pocket L(1) (notation in accordance with Cook's BzR topological model) is asymmetric and highlighted the stereoelectronic and conformational properties of the amide side chain required for high potency. Several of the new indoles showed selectivity for the alpha(1)beta(2)gamma(2) subtype compared with the alpha(3)beta(2)gamma(2) and alpha(5)beta(3)gamma(2) subtypes (e.g.: 4t and 7c bind to these three BzR isoforms with K(i) values of 14 nM, 283 nM, 239 nM, and 9 nM, 1960 nM, 95 nM, respectively). The GABA ratios close to unity exhibited by all the tested compounds on each BzR subtype were predictive of an efficacy profile typical of antagonists.

Synthesis and preliminary pharmacological evaluation of 5-hydroxy- and 5,6-dihydroxy-1,2,3,7,12,12a-hexahydrobenzo[5,6]cyclohepta[1,2,3-ij]isoquinoline derivatives as dopamine receptor ligands

A series of 5-hydroxy- and 5,6-dihydroxy-1,2,3,7,12,12a-hexahydrobenzo[5,6]cyclohepta[1,2,3-ij]isoquinoline derivatives (5a--e and 6a--e) were synthesized as conformationally rigid analogues of 1-benzyltetrahydroisoquinoline and evaluated for their affinity at D(1) and D(2) dopamine receptors. All compounds showed lower D(1) and D(2) affinities than dopamine. The 5-hydroxy-1-methyl-2,3,12,12a-hexahydrobenzo[5,6]cyclohepta[1,2,3-ij]isoquinoline 5a and the 5,6-dihydroxy analogue 6a showed D(2) agonist activity. This was proved by their effects on prolactin release from primary cultures of rat anterior pituitary cells. Molecular modeling studies showed that the geometric parameters (namely the distances from meta and para hydroxyl oxygens to the nitrogen and the height of nitrogen from the hydroxylated phenyl ring plane) of the dopaminergic pharmacophore embedded in our compounds have lower values in comparison with those observed in D(1) and D(2) selective ligands.

The A3 adenosine receptor induces cytoskeleton rearrangement in human astrocytoma cells via a specific action on Rho proteins

In previous studies, we have demonstrated that exposure of astroglial cells to A3 adenosine receptor agonists results in dual actions on cell survival, with "trophic" and antiapoptotic effects at nanomolar concentrations and induction of cell death at micromolar agonist concentrations. The protective actions of A3 agonists have been associated with a reinforcement of the actin cytoskeleton, which likely results in increased resistance of cells to cytotoxic stimuli. The molecular mechanisms at the basis of this effect and the signalling pathway(s) linking the A3 receptor to the actin cytoskeleton have never been elucidated. Based on previous literature data suggesting that the actin cytoskeleton is controlled by small GTP-binding proteins of the Rho family, in the study reported here we investigated the involvement of these proteins in the effects induced by A3 agonists on human astrocytoma ADF cells. The presence of the A3 adenosine receptor in these cells has been confirmed by immunoblotting analysis. As expected, exposure of human astrocytoma ADF cells to nanomolar concentrations of the selective A3 agonist 2-chloro-N6-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (CI-IB-MECA) resulted in formation of thick actin positive stress fibers. Preexposure of cells to the C3B toxin that inactivates Rho-proteins completely prevented the actin changes induced by CI-IB-MECA. Exposure to the A3 agonist also resulted in significant reduction of Rho-GDI, an inhibitory protein known to maintain Rho proteins in their inactive state, suggesting a potentiation of Rho-mediated effects. This effect was fully counteracted by the concomitant exposure to the selective A3 receptor antagonist MRS1191. These results suggest that the reinforcement of the actin cytoskeleton induced by A3 receptor agonists is mediated by an interference with the activation/inactivation cycle of Rho proteins, which may, therefore, represent a biological target for the identification of novel neuroprotective strategies.

Regional variations of insulin-like growth factor I (IGF-I), IGF-II, and receptor type I in benign prostatic hyperplasia tissue and their correlation with intraprostatic androgens

Benign prostatic hyperplasia (BPH) is an androgen-dependent disease; it originates exclusively in the inner prostate, which includes tissue surrounding the urethra. Stromal-epithelial interaction has a pivotal role in the regulation of the development and growth of the prostate, and locally produced peptide growth factors are considered important mediators of this interaction. Insulin-like growth factor I (IGF-I) and IGF-II, acting mainly through type 1 IGF receptor (IGFR1), have mitogenic and antiapoptotic effects on epithelial and stromal prostatic cells. In this study the expression of IGF-I, IGF-II, and IGFR1 messenger ribonucleic acid (mRNA), the immunoreactive content of IGF-I (irIGF-I) and IGF-II (irIGF-II) were determined in periurethral, intermediate, and subcapsular regions of BPH tissue to verify their possible regional variation; a correlation to the tissue levels of dihydrotestosterone (DHT) and 3 alpha-androstanediol (3 alpha Diol) was also determined to verify their possible androgen dependence. Prostates were removed by suprapubic prostatectomy from 14 BPH patients and sectioned in the periurethral, intermediate, and subcapsular regions. Gene expression of IGF-I, IGF-II, and IGFR1 was evaluated by semiquantitative RT-PCR, using beta-actin as a control. irIGF-I was measured by RIA, and irIGF-II was measured by IRMA after acidification and chromatography on Sep-Pak C(18) cartridges. DHT and 3 alpha Diol concentrations were evaluated by RIA after extraction and purification on Celite microcolumns. IGF-II and IGFR1, but not IGF-I, mRNA was higher in the periurethral than in the intermediate (P < 0.05) and subcapsular (P < 0.01) region. Also, prostatic levels of irIGF-II, expressed as picomoles per g tissue, were higher in the periurethral (20.84 +/- 1.84) than in the intermediate (14.81 +/- 2.11; P < 0.05) and subcapsular (10.88 +/- 1.21; P < 0.001) region. No significant differences were found in irIGF-I content. Considering prostatic androgen levels, DHT and 3alphaDiol presented a regional variation, with the highest concentrations in the periurethral region. IGF-II mRNA and irIGF-II levels were positively correlated with both DHT and 3 alpha Diol content. These results demonstrate that in BPH tissue a greater IGF-II activity is present in the periurethral region, the site of origin of BPH. Moreover, we can hypothesize that the tissue androgen content may modulate prostatic production of IGF-II, acting at the transcriptional and probably the posttranscriptional level. Therefore, even though further studies will need to confirm this hypothesis, DHT may increase IGF-II activity, mainly in the periurethral region, which, in turn, induces, through IGFR1, benign proliferation of both epithelial and stromal cells, characteristic of BPH.

Peripheral-type benzodiazepine receptor ligands: mitochondrial permeability transition induction in rat cardiac tissue

Strong evidence is emerging that mitochondrial permeability transition (MPT) may be important in certain physiological conditions and, above all, in the processes of cell damage and death. Reversible MPT, triggered by inducing agents in the presence of calcium ions, has resulted in the opening of a dynamic multiprotein complex formed in the inner mitochondrial membrane and has caused large-amplitude mitochondrial swelling. In the present work, the exposure of de-energized rat cardiac mitochondria to peripheral benzodiazepine receptor (PBR) ligands (1-(2-chlorophenyl-N-methyl-1-methylpropyl)-3-isoquinolinecarboxamide (PK 11195), 7-chloro-5-(4-chlorophenyl)-1,3-dihydro-1-methyl-2H-1,4-benzodiazepin-2-one (Ro5-4864), and diazepam) produced a dose-dependent and cyclosporin A (CSP)-sensitive loss of absorbance, which was indicative of mitochondrial swelling. By contrast, the addition of a high-affinity central benzodiazepine receptor ligand (clonazepam) was ineffective, even at the highest concentration tested. The ultrastructural changes associated with swelling were similar in mitochondria exposed either to PK 11195 or to calcium. Supporting the apoptotic role of PK 11195-induced swelling, supernatants from mitochondria that had undergone permeability transition caused apoptotic changes in isolated cardiac nuclei. In addition, ultrastructural abnormalities were observed in rat cardiac tissue following in vivo PK 11195 administration, with these abnormalities being prevented by CSP co-administration. These data indicate that PBR ligands induce mitochondrial permeability transition and ultrastructural alterations in isolated cardiac mitochondria as well as in myocardiocytes, suggesting a novel strategy for studying the implication of PBR ligands as apoptosis inducers, through a probable effect on the MPT pore.

3-Aryl[1,2,4]triazino[4,3-a]benzimidazol-4(10H)-ones: a new class of selective A1 adenosine receptor antagonists

Radioligand binding assays using bovine cortical membrane preparations and biochemical in vitro studies revealed that various 3-aryl[1,2,4]triazino[4,3-a]benzimidazol-4(10H)-one (ATBI) derivatives, previously reported by us as ligands of the central benzodiazepine receptor (BzR) (Primofiore, G.; et al. J. Med. Chem. 2000, 43, 96-102), behaved as antagonists at the A1 adenosine receptor (A1AR). Alkylation of the nitrogen at position 10 of the triazinobenzimidazole nucleus conferred selectivity for the A1AR vs the BzR. The most potent ligand of the ATBI series (10-methyl-3-phenyl[1,2,4]triazino[4,3-a]benzimidazol-4(10H)-one 12) displayed a Ki value of 63 nM at the A1AR without binding appreciably to the adenosine A2A and A3 nor to the benzodiazepine receptor. Pharmacophore-based modeling studies in which 12 was compared against a set of well-established A1AR antagonists suggested that three hydrogen bonding sites (HB1 acceptor, HB2 and HB3 donors) and three lipophilic pockets (L1, L2, and L3) might be available to antagonists within the A1AR binding cleft. According to the proposed pharmacophore scheme, the lead compound 12 engages interactions with the HB2 site (via the N2 nitrogen) as well as with the L2 and L3 sites (through the pendant and the fused benzene rings). The results of these studies prompted the replacement of the methyl with more lipophilic groups at the 10-position (to fill the putative L1 lipophilic pocket) as a strategy to improve A1AR affinity. Among the new compounds synthesized and tested, the 3,10-diphenyl[1,2,4]triazino[4,3-a]benzimidazol-4(10H)-one (23) was characterized by a Ki value of 18 nM which represents a 3.5-fold gain of A1AR affinity compared with the lead 12. A rhodopsin-based model of the bovine adenosine A1AR was built to highlight the binding mode of 23 and two well-known A1AR antagonists (III and VII) and to guide future lead optimization projects. In our docking simulations, 23 receives a hydrogen bond (via the N1 nitrogen) from the side chain of Asn247 (corresponding to the HB1 and HB2 sites) and fills the L1, L2, and L3 lipophilic pockets with the 10-phenyl, 3-phenyl, and fused benzene rings, respectively.