Large deletion mutation of SPAST in a multi-generation family from Sardinia

BACKGROUND AND PURPOSE

The hereditary spastic paraplegias (HSP) are characterized by progressive spasticity of the lower limbs, mostly inherited as an autosomal dominant trait. Analyses of large HSP pedigrees could help to better characterize the phenotype due to a single causative mutation. Patients in a seven-generation kindred carrying a large deletion in SPAST/SPG4 are described.

METHODS

Individuals originating from Sardinia were clinically and genetically studied.

RESULTS

Sixty-seven subjects carried a heterozygous deletion encompassing exons 2-17 of SPAST. Fifty patients (53.2 ± 15.4 years) presented a pure form of spastic paraparesis characterized by mild impairment and slow progression. Most patients showed spasticity, increased tendon reflexes in the lower limbs and Babinski sign, whilst weakness was rarely detected and urinary disturbances occasionally reported. Amongst the 17 asymptomatic carriers of the mutation, minimal neurological signs were detected in 11 cases.

CONCLUSIONS

A focus on spasticity, increased tendon reflexes and Babinski sign, more than on weakness, could help clinicians to promote early diagnosis in asymptomatic carriers of SPAST deletions.

Pure akinesia: a kinematic analysis in a case responsive to rotigotine

A patient with pure akinesia is described. This rare gait disorder, poorly responsive to therapy, is characterized by gait impairment which may be associated with handwriting and speech difficulties, in the absence of further signs of extrapyramidal involvement. Here, we report the improvement in a patient suffering from pure akinesia after low doses of rotigotine, a non-ergolinic dopamine agonist, detailing the kinematic analysis before and after the treatment. After therapy, an improvement in all of the gait parameters, particularly gait speed, was observed with a trend toward normalization. Our case report suggests that rotigotine may be a therapeutic option in cases of pure akinesia.

Substituted tetraazaacenaphthylenes as potent CRF1 receptor antagonists for the treatment of depression and anxiety

Two isomers of the hexahydro-tetraazaacenaphthylene templates (1 and 2) are presented as novel, potent, and selective corticotropin releasing factor-1 (CRF1) receptor antagonists. In this paper, we report the affinity and SAR of a series of compounds, as well as pharmacokinetic characterization of a chosen set. The anxiolitic activity of a selected example (2ba) in the rat pup vocalization model is also presented.

Synthesis and pharmacological characterisation of a conformationally restrained series of indole-2-carboxylates as in vivo potent glycine antagonists

After the identification of GV150526, the indole-2-carboxylate template was further explored in order to identify novel potential anti-stroke agents. In particular, the SAR of the side chain present at the C-3 position of the indole nucleus was widely studied. In this paper, the synthesis and the pharmacological profile of a further class of conformationally restricted analogues of GV150526 as in vitro and in vivo potent glycine antagonists is reported. In particular, a pyrazolidinone derivative was identified as a potent neuroprotective agent in animal models of cerebral ischaemia.

A new alternative synthesis of 5-cyanophthalide, a versatile intermediate in the preparation of the antidepressant drug citalopram

An alternative versatile synthesis of 5-cyanophthalide, a key synthetic intermediate in the preparation of the antidepressant drug Citalopram, is presented. The synthesis reported here allows the preparation of this important intermediate in three steps, avoiding the manipulation of environmentally detrimental cyanides.

Synthesis and pharmacological properties of novel glycine antagonists

The NMDA receptor is an ionotropic receptor complex widely distributed in the central nervous system and its activation, particularly in hypoxic conditions such as stroke, traumatic head injury and hypoglycemia, results in a massive influx of calcium ions into the post-synaptic neurones, leading to cell death through the activation of several neurotoxic cascades. The NMDA receptor is a unique ionotropic receptor complex because its activation requires the simultaneous binding of glutamate and glycine and selective antagonists at the glycine binding site are endowed with a better side-effect profile than competitive NMDA antagonists. Then, considerable efforts have been devoted to find potent and selective ligands, resulting in the identification of several classes of glycine antagonists. The research at Glaxo Wellcome has been aimed at the identification of novel in vivo active glycine antagonists, and led to the synthesis and pharmacological characterization of a number of novel, potent and systemically active compounds belonging to different chemical classes.

Substituted analogues of GV150526 as potent glycine binding site antagonists in animal models of cerebral ischemia

A series of analogues of the indole-2-carboxylate GV150526, currently in clinical trials as a potential neuroprotective agent for the control of the cerebral damage after stroke onset, was designed based on previous studies dealing with the electronic features of the north-east region of the glycine binding site associated with the NMDA receptor. In particular, the substitution of the para position of the terminal phenyl ring of GV150526 with suitable hydrophilic groups resulted in the identification of a new class of glycine antagonists. These compounds exhibited nanomolar in vitro affinity to the glycine binding site, high receptor selectivity, and outstanding in vivo potency. In particular, 3-[(E)-2-[(4-ureidomethylphenyl)aminocarbonyl]ethenyl]-4, 6-dichloroindole-2-carboxylic acid was found to be highly effective in the middle cerebral artery occlusion (MCAo) model in the rat, an animal model of focal ischemia, when given both prior to and after the occlusion of the middle cerebral artery. Notably, a significant neuroprotective effect was seen in this model postischaemia, when the administration of this compound was delayed up to 6 h from the occlusion of the middle cerebral artery, further confirming the wide therapeutic window seen for GV150526A.

Substituted indole-2-carboxylates as potent antagonists of the glycine binding site associated with the NMDA receptor

A novel series of indole-2-carboxylate analogues of GV150526 (1) in which the propenoic double bond was substituted with different "probes" or replaced by a isosteric cyclopropyl moiety were synthesized and evaluated for their affinity profile in order to obtain further information on the pharmacophoric model of the glycine binding site associated to the NMDA receptor.

Asymmetric synthesis of some substituted-3-phenyl prolines

The asymmetric synthesis of carboxyphenyl prolines was performed according to Schöllkopf methodology, to prepare possible antagonists of the metabotropic glutamate receptor mGluR1.

Potent antihyperalgesic activity without tolerance produced by glycine site antagonist of N-methyl-D-aspartate receptor GV196771A

Central sensitization is a condition of enhanced excitability of spinal cord neurons that contributes to the exaggerated pain sensation associated with chronic tissue or nerve injury. N-methyl-D-aspartate (NMDA) receptors are thought to play a key role in central sensitization. We have tested this hypothesis by characterizing in vitro and in vivo a novel antagonist of the NMDA receptor acting on its glycine site, GV196771A. GV196771A exhibited an elevated affinity for the NMDA glycine binding site in rat cerebral cortex membranes (pKi = 7.56). Moreover, GV196771A competitively and potently antagonized the activation of NMDA receptors produced by glycine in the presence of NMDA in primary cultures of cortical, spinal, and hippocampal neurons (pKB = 7.46, 8. 04, and 7.86, respectively). In isolated baby rat spinal cords, 10 microM GV196771A depressed wind-up, an electrical correlate of central sensitization. The antihyperalgesic properties of GV196771A were studied in a model of chronic constriction injury (CCI) of the rat sciatic nerve and in the mice formalin test. In the CCI model GV196771A (3 mg/kg twice a day p.o.), administered before and then for 10 days after nerve ligature, blocked the development of thermal hyperalgesia. Moreover, GV196771A (1-10 mg/kg p.o.) reversed the hyperalgesia when tested after the establishment of the CCI-induced hyperalgesia. In the formalin test GV196771A (0.1-10 mg/kg p.o.) dose-dependently reduced the duration of the licking time of the late phase. These antihyperalgesic properties were not accompanied by development of tolerance. These observations strengthen the view that NMDA receptors play a key role in the events underlying plastic phenomena, including hyperalgesia. Moreover, antagonists of the NMDA glycine site receptor could represent a new analgesic class, effective in conditions not sensitive to classical opioids.

Cycloalkyl indole-2-carboxylates as useful tools for mapping the "north-eastern" region of the glycine binding site associated with the NMDA receptor

A novel series of indole-2-carboxylate analogues of GV 150526 (1) in which the terminal phenyl ring belonging to the side chain present in the position C-3 has been replaced with a bridged cycloalkyl group was synthesized and evaluated for its pharmacological profile. Modelling studies on this class of novel glycine antagonist allowed us to identify an asymmetric lipophilic pocket present in the "North-Eastern" region of the pharmacophoric model of the glycine binding site associated to the NMDA receptor. Among the derivatives prepared, 3-[2-(1-adamantylaminocarbonyl)ethenyl]-4,6-dichloroindole-2 -carboxylic acid 6b and 3-[2-(norbornylaminocarbonyl)ethenyl]-4,6-dichloroindole-2-c arboxylic acid 6l were found to be antagonists acting at the strychnine-insensitive glycine binding site, showing nanomolar affinity for the glycine binding site (Ki = 63 and 19 nM, respectively), coupled with high glutamate receptor selectivity (IC50 > 10(-5) M at the NMDA, AMPA, KA binding sites) and high in vivo potency after systemic administration by inhibition of convulsion induced by NMDA in mice.

New synthesis of substituted 2-carboxyindole derivatives: versatile introduction of a carbamoylethynyl moiety at the C-3 position

A novel series of 3-carbamoylethynyl-2-carboxyindoles, antagonists acting at the strychnine-insensitive glycine binding site associated with the NMDA receptor, has been synthesised. This new versatile approach involves the introduction of a 2-chloroethenyl moiety in position C-3 with subsequent derivatisation of the terminal carboxyl group, followed by an unusual elimination of HCl to afford the ethynyl functionality. This novel series of glycine antagonists was evaluated in terms of in vitro affinity at the glycine binding site and the most potent compound was tested in vivo in the NMDA-induced convulsions model in mice.

3-(2-Carbamoylvinyl)-4,5-dimethylpyrrole-2-carboxylic acids as ligands at the NMDA glycine-binding site: a study on the 2-carbamoylvinyl chain modification

Twenty 4,5-dimethylpyrrole-2-carboxylic acids (5a-t) with different 2-carbamoylvinyl chains in position 3 were prepared to further investigate the relationships between structure and in vitro affinity for the strychnine-insensitive glycine-binding site. None of these compounds was superior to (E)-3-(N-phenyl-2-carbamoylvinyl)-4,5-dimethylpyrrole-2-carb oxylic acid III (pKi = 6.70), which was taken as a reference standard, but overall the results obtained indicate that the N-phenyl-2-carbamoylvinyl substituent of III may be replaced with the N-(1-adamantyl)-2-carbamoylvinyl group as in 5h (pKi = 6.20) without considerable loss of affinity. This finding adds to previous knowledge.

Unusual synthesis of new glycine antagonists via sequential aldol condensation-lactonization-elimination reaction

Compounds 2 and 3 were designed in order to probe the North-East region of the strichnine-insensitive glycine binding site of the NMDA receptor. The two products were obtained readily by a tandem aldol condensation-lactonization-elimination step which affords the desired E isomer with complete regioselection.

(E)-3-(2-(N-phenylcarbamoyl)vinyl)pyrrole-2-carboxylic acid derivatives. A novel class of glycine site antagonists

The synthesis and preliminary biological evaluation of novel (E)-3-(2-(N-phenylcarbamoyl)-vinyl)pyrrole-2-carboxylic acids bearing alkyl, acyl, alkoxy, phenyl, and halo substituents at the 4- and 5-positions of the pyrrole ring are reported. These compounds were studied for their in vitro affinity at the strychnine-insensitive glycine-binding site of the N-methyl-D-aspartate (NMDA) receptor complex. In the [3H]glycine binding assay (E)-4,5-dibromo-3-(2-(N-phenylcarbamoyl)vinyl)pyrrole-2-carboxylic acid 6w (pKi = 7.95 +/- 0.01) and the 4-bromo-5-methyl 6j (pKi = 7.24 +/- 0.01) and 4,5-dimethyl 6g (pKi = 6.70 +/- 0.03) analogues were the most active compounds of the series. Qualitative structure-activity analysis points to a negative correlation between bulk of the C-4 and C-5 substituents and affinity which is enhanced by halo-substituents. QSAR analysis by the Hansch descriptors F, R, pi, and MR, on a subset of compounds with pKi > or = 4, indicates that electron-withdrawing groups at C-4 and C-5 enhance the affinity. Bulk and lipophilicity are also relevant for the substituents at these positions. 6g was found to be a full antagonist (alpha = 0; enhancement of the [3H]TCP binding). The in vivo potency of 6g, 6j, and 6w was evaluated by the inhibition of NMDA-induced convulsions in mice by both the i.v. and po routes; 6w was the most active compound (ED50 = 3 x 10(-3) (0.8-10) g/kg, i.v. and 30 x 10(-3) (4.5-61) g/kg, p.o.). The results of this study indicate that the 3,4-disubstitutedpyrrole-2-carboxylate represents a novel template for the design of new glycine antagonists.

Substituted indole-2-carboxylates as in vivo potent antagonists acting as the strychnine-insensitive glycine binding site

A series of indole-2-carboxylates bearing suitable chains at the C-3 position of the indole nucleus was synthesized and evaluated in terms of in vitro affinity using [3H]glycine binding assay and in vivo potency by inhibition of convulsions induced by N-methyl-D-aspartate (NMDA) in mice. 3-[2-[(Phenylamino)carbonyl]ethenyl]-4,6-dichloroindole-2-carboxyl ic acid (8) was an antagonist at the strychnine-insensitive glycine binding site (noncompetitive inhibition of the binding of [3H]TCP, pA2 = 8.1) displaying nanomolar affinity for the glycine binding site (pKi = 8.5), coupled with high glutamate receptor selectivity (> 1000-fold relative to the affinity at the NMDA, AMPA, and kainate binding sites). This indole derivative inhibited convulsions induced by NMDA in mice, when administered by both iv and po routes (ED50 = 0.06 and 6 mg/kg, respectively). The effect of the substituents on the terminal phenyl ring of the C-3 side chain was investigated. QSAR analysis suggested that the pKi value decreases with lipophilicity and steric bulk of substituents and increases with the electron donor resonance effect of the groups present in the para position of the terminal phenyl ring. According to these results the terminal phenyl ring of the C-3 side chain should lie in a nonhydrophobic pocket of limited size, refining the proposed pharmacophore model of the glycine binding site associated with the NMDA receptor.