SPG11 – the most common type of recessive spastic paraplegia in Norway?

Background –  Hereditary spastic paraplegias (HSP) are neurodegenerative diseases mainly characterized by lower limb spasticity with additional neurological symptoms and signs in complicated forms. Among the many autosomal recessive forms, SPG11 appears to be one of the most frequent.
Objective –  Our objective was to select potential SPG11 patients based on phenotypes in our material, identify eventual disease-causing variants with the collaboration of laboratories abroad, estimate the frequency and spectrum of SPG11-mutations and describe their associated phenotypes.
Material and Methods –  Two isolated cases and two affected members of one family with cognitive impairment and confirmed thin corpus callosum on magnetic resonance imaging were selected from our database for inclusion into a multicenter study.
Results –  Mutations were found in the two isolated cases but not in the proband of the family. Conclusion – We present the first SPG11-HSP in the Norwegian population. SPG11 should be suspected in patients with isolated or recessive HSP, thin corpus callosum and mental retardation.     

Characterization and evaluation of chitosan nanoparticles for dopamine brain delivery

The aim of this study was to characterize nanoparticles (NPs) composed of chitosan (CS) and evaluate their potential for brain delivery of the neurotransmitter Dopamine (DA). For this purpose, CS based NPs were incubated with DA at two different concentrations giving rise to nanocarriers denoted as DA/CSNPs (1) and DA/CSNPs (5), respectively. X-ray Photoelectron Spectroscopy (XPS) analysis confirmed that DA was adsorbed onto the external surface of such NPs. The cytotoxic effect of the CSNPs and DA/CSNPs was assessed using the MTT test and it was found that the nanovectors are less cytotoxic than the neurotransmitter DA after 3 h of incubation time. Transport studies across MDCKII-MDR1 cell line showed that DA/CSNPs (5) give rise to a significant transport enhancing effect compared with the control and greater than the corresponding DA/CSNPs (1). Measurement of reactive oxygen species (ROS) suggested a low DA/CSNPs neurotoxicity after 3 h. In vivo brain microdialysis experiments in rat showed that intraperitoneal acute administration of DA/CSNPs (5) (6-12 mg/kg) induced a dose-dependent increase in striatal DA output. Thus, these CS nanoparticles represent an interesting technological platform for DA brain delivery and, hence, may be useful for Parkinson's disease treatment.     

New Fluorescent Probes Targeting the Mitochondrial-Located Translocator Protein 18 kDa (TSPO) as Activated Microglia Imaging Agents

Purpose  

To evaluate the utility of new Translocator protein 18 kDa (TSPO)-targeted fluorescent probes for in vivo molecular imaging of activated microglia.     

Tunisian hereditary spastic paraplegias: clinical variability supported by genetic heterogeneity

Hereditary spastic paraplegias (HSP) constitute a clinically and genetically heterogeneous group of neurodegenerative disorders characterized by slowly progressive spasticity of the lower extremities. We performed the first clinical, epidemiological and genetic study of HSP in Southern Tunisia. We investigated 88 patients belonging to 38 unrelated Tunisian HSP families. We could establish the minimal prevalence of HSP in the district of Sfax at 5.75/100,000. Thirty‐one percent of the families had a pure HSP, whereas 69% had a complicated form. The mode of inheritance was almost exclusively compatible with an autosomal recessive trait (97%, 37/38). Taking into account previously published results and new data generated in this work, genetic studies revealed significant or putative linkage to known HSP loci in 13 families (34.2%) to either SPG11 (7/38, 18.4%), SPG15 (4/38, 10.5%) or to SPG4 and SPG5 in one family each. The linkage results could be validated through the identification of two recurrent truncating mutations (R2034X and M245VfsX246) in the SPG11 gene, three different mutations (Q493X, F683LfsX685 and the novel S2004T/r.?) in the SPG15 gene, the recurrent R499C mutation in the SPG4 gene as well as the new R112X mutation in the SPG5 gene. SPG11 and SPG15 are the major responsible HSP genes in Tunisia.     

Comparative effects of some hydrophilic excipients on the rate of gabapentin and baclofen lactamization in lyophilized formulations

The aim of this study was to gain insights into the role played by some excipients on the stability of gabapentin 1 and baclofen 2 which can undergo degradation giving rise to the corresponding lactams 2-azaspiro[4.5]decan-3-one 3 and 4-(4-chlorophenyl)-2-pyrrolidone 4, respectively. A screening study was carried out on drug and drug-excipient freeze-dried mixtures at 50 degrees C and under three different humidity values by using a number of commonly available excipients. These include hydroxypropyl-beta-(HP-beta-CD), sulfobutyl-beta-cyclodextrin (SBE-beta-CD), lactose, raffinose, trehalose, PVP-K30 and mannitol. For most cases, it was found that the lactam formation can be satisfactory described by an apparent zero-order equation. Excipients shown to negatively impact gabapentin stability are HP-beta-CD, SBE-beta-CD, lactose and PVP K30 while only this last excipient had a significant effect on the degradation of baclofen. The results can be rationalized in terms of conformational factors favouring the intramolecular dehydration reaction. A positive effect of moisture on the lactamization process was observed under some circumstances. Water may provide a favourable environment for degradation. These findings, taken together, should be considered during the selection of excipients for a possible formulation of gabapentin and baclofen.     

Novel L-Dopa and Dopamine Prodrugs Containing a 2-Phenyl-imidazopyridine Moiety

Purpose The aim of this study was to gain insight into the feasibility of enhancing the delivery of L-Dopa and dopamine to the brain by linking these neurotransmitters and L-Dopa ethyl ester to 2-phenyl-3-carboxymethyl-imidazopyridine compounds giving rise to the so-called Dopimid compounds. Materials and Methods A number of Dopimid compounds were synthesized and both stability and binding studies to dopaminergic and benzodiazepine receptors were performed. To evaluate whether Dopimid compounds are P-gp substrates, [³H]ritonavir uptake experiments and bi-directional transport studies on confluent MDCKII-MDR1 monolayers were carried out. The brain penetration properties of Dopimid compounds were estimated by the Clark’s computational model and evaluated by investigation of their transport across BBMECs monolayers. The dopamine levels following the intraperitoneal administration of the selected Dopimid compounds were measured in vivo by using brain microdialysis in rat. Results Tested compounds were adequately stable in solution buffered at pH 7.4 but undergo faster cleavage in dilute rat serum at 37°C. Receptor binding studies showed that Dopimid compounds are essentially devoid of affinity for dopaminergic and benzodiazepine receptors. [³H]ritonavir uptake experiments indicated that selected Dopimid compounds, like L-Dopa and dopamine hydrochloride, are not substrates of P-gp and it was also confirmed by bi-directional transport experiments across MDCKII-MDR1 monolayers. By Clark’s model a significant brain penetration was deduced for L-Dopa ethyl ester and dopamine derivatives. Transport studies involving BBMECs monolayers indicated that some of these compounds should be able to cross the BBB. Interestingly, the rank order of apparent permeability (P _app) values observed in these assays parallels that calculated by the computational approach. Brain microdialysis experiments in rat showed that intraperitoneal acute administration of some Dopimid compounds induced a dose-dependent increase in cortical dopamine output. Conclusion Based on these results, it may be concluded that some Dopimid compounds can be proposed as novel L-Dopa and dopamine prodrugs.     

Structural and metabolic damage in brains of patients with SPG11-related spastic paraplegia as detected by quantitative MRI

The goal of this work was to assess brain structural and metabolic abnormalities of subjects with SPG11 and their relevance to clinical disability by using quantitative magnetic resonance (MR) metrics. Autosomal recessive hereditary spastic paraplegia (AR-HSP) with thin corpus callosum and cognitive decline is a complex neurological disorder caused by mutations in the SPG11 gene in most cases. Little is known about the process leading to corticospinal and white matter degeneration. We performed conventional MRI/MR spectroscopic imaging ((1)H-MRSI) examinations in 10 HSP patients carrying an SPG11 mutation and in 10 demographically matched healthy controls (HC). We measured in each subject cerebral white matter hyperintensities (WMHs), normalized global and cortical brain volumes, and (1)H-MRSI-derived central brain levels of N-acetylaspartate (NAA) and choline (Cho) normalized to creatine (Cr). Clinical disability was assessed according to patients' autonomy in walking. Conventional MRI showed WMHs in all patients. Global brain volumes were lower in patients than in HC (p < 0.001). Decreased values were diffusely found also in cortical regions (p < 0.01). On (1)H-MRSI, NAA/Cr values were lower in SPG11 patients than in HC (p = 0.002). Cho/Cr values did not differ between patients and HC. Cerebral volume decreases and NAA/Cr in the corona radiata correlated closely with increasing disability scores (p < 0.05). Quantitative MR measures propose that widespread structural and metabolic brain damage occur in SPG11 patients. The correlation of these MR metrics with measures of patients' disease severity suggests that they might represent adequate surrogate markers of disease outcome.     

Synthesis and characterization of a platinum(II) complex tethered to a ligand of the peripheral benzodiazepine receptor

A peripheral benzodiazepine receptor (PBR) ligand (TZ6, 5) has been selected as receptor-mediated carrier for antitumor cisplatin-like compounds. Compound 5, containing a thiazole ring in position 2 of the imidazopyridine nucleus, is able to act as a dinitrogen chelate toward platinum. The resulting complex, cis-[PtCl2(5)], that is, compound 8, has been fully characterized by NMR techniques and has been shown to possess affinity and selectivity for the PBR comparable to those of 5 (IC50 of 4.6 and 2.81 nM for 8 and 5, respectively; selectivity indexes for PBR greater than 10,000 for both compounds). Hence, a platinum moiety cross-linking the imidazopyridine and the thiazole aromatic rings does not alter the affinity for PBR. The same cross-linking could be responsible for the tendency of 8 to associate in dimers. The equilibrium between monomer and dimer has been investigated by NMR spectroscopy and the corresponding constant determined.