Genetic and phenotypic characterization of complex hereditary spastic paraplegia

The hereditary spastic paraplegias are a heterogeneous group of degenerative disorders that are clinically classified as either pure with predominant lower limb spasticity, or complex where spastic paraplegia is complicated with additional neurological features, and are inherited in autosomal dominant, autosomal recessive or X-linked patterns. Genetic defects have been identified in over 40 different genes, with more than 70 loci in total. Complex recessive spastic paraplegias have in the past been frequently associated with mutations in SPG11 (spatacsin), ZFYVE26/SPG15, SPG7 (paraplegin) and a handful of other rare genes, but many cases remain genetically undefined. The overlap with other neurodegenerative disorders has been implied in a small number of reports, but not in larger disease series. This deficiency has been largely due to the lack of suitable high throughput techniques to investigate the genetic basis of disease, but the recent availability of next generation sequencing can facilitate the identification of disease- causing mutations even in extremely heterogeneous disorders. We investigated a series of 97 index cases with complex spastic paraplegia referred to a tertiary referral neurology centre in London for diagnosis or management. The mean age of onset was 16 years (range 3 to 39). The SPG11 gene was first analysed, revealing homozygous or compound heterozygous mutations in 30/97 (30.9%) of probands, the largest SPG11 series reported to date, and by far the most common cause of complex spastic paraplegia in the UK, with severe and progressive clinical features and other neurological manifestations, linked with magnetic resonance imaging defects. Given the high frequency of SPG11 mutations, we studied the autophagic response to starvation in eight affected SPG11 cases and control fibroblast cell lines, but in our restricted study we did not observe correlations between disease status and autophagic or lysosomal markers. In the remaining cases, next generation sequencing was carried out revealing variants in a number of other known complex spastic paraplegia genes, including five in SPG7 (5/97), four in FA2H (also known as SPG35) (4/97) and two in ZFYVE26/SPG15. Variants were identified in genes usually associated with pure spastic paraplegia and also in the Parkinson’s disease-associated gene ATP13A2, neuronal ceroid lipofuscinosis gene TPP1 and the hereditary motor and sensory neuropathy DNMT1 gene, highlighting the genetic heterogeneity of spastic paraplegia. No plausible genetic cause was identified in 51% of probands, likely indicating the existence of as yet unidentified genes

Visual short-term memory deficits associated with GBA mutation and Parkinson's disease.

Individuals with mutation in the lysosomal enzyme glucocerebrosidase (GBA) gene are at significantly high risk of developing Parkinson's disease with cognitive deficit. We examined whether visual short-term memory impairments, long associated with patients with Parkinson's disease, are also present in GBA-positive individuals-both with and without Parkinson's disease. Precision of visual working memory was measured using a serial order task in which participants observed four bars, each of a different colour and orientation, presented sequentially at screen centre. Afterwards, they were asked to adjust a coloured probe bar's orientation to match the orientation of the bar of the same colour in the sequence. An additional attentional 'filtering' condition tested patients' ability to selectively encode one of the four bars while ignoring the others. A sensorimotor task using the same stimuli controlled for perceptual and motor factors. There was a significant deficit in memory precision in GBA-positive individuals-with or without Parkinson's disease-as well as GBA-negative patients with Parkinson's disease, compared to healthy controls. Worst recall was observed in GBA-positive cases with Parkinson's disease. Although all groups were impaired in visual short-term memory, there was a double dissociation between sources of error associated with GBA mutation and Parkinson's disease. The deficit observed in GBA-positive individuals, regardless of whether they had Parkinson's disease, was explained by a systematic increase in interference from features of other items in memory: misbinding errors. In contrast, impairments in patients with Parkinson's disease, regardless of GBA status, was explained by increased random responses. Individuals who were GBA-positive and also had Parkinson's disease suffered from both types of error, demonstrating the worst performance. These findings provide evidence for dissociable signature deficits within the domain of visual short-term memory associated with GBA mutation and with Parkinson's disease. Identification of the specific pattern of cognitive impairment in GBA mutation versus Parkinson's disease is potentially important as it might help to identify individuals at risk of developing Parkinson's disease

Genotype–phenotype correlation in PRKN- associated Parkinson’s disease

Bi-allelic pathogenic variants in PRKN are the most common cause of autosomal recessive Parkinson’s disease (PD). 647 patients with PRKN-PD were included in this international study. The pathogenic variants present were characterised and investigated for their effect on phenotype. Clinical features and progression of PRKN-PD was also assessed. Among 133 variants in index cases (n = 582), there were 58 (43.6%) structural variants, 34 (25.6%) missense, 20 (15%) frameshift, 10 splice site (7.5%%), 9 (6.8%) nonsense and 2 (1.5%) indels. The most frequent variant overall was an exon 3 deletion (n = 145, 12.3%), followed by the p.R275W substitution (n = 117, 10%). Exon3, RING0 protein domain and the ubiquitin-like protein domain were mutational hotspots with 31%, 35.4% and 31.7% of index cases presenting mutations in these regions respectively. The presence of a frameshift or structural variant was associated with a 3.4 ± 1.6 years or a 4.7 ± 1.6 years earlier age at onset of PRKN-PD respectively (p < 0.05). Furthermore, variants located in the N-terminus of the protein, a region enriched with frameshift variants, were associated with an earlier age at onset. The phenotype of PRKN-PD was characterised by slow motor progression, preserved cognition, an excellent motor response to levodopa therapy and later development of motor complications compared to early-onset PD. Non-motor symptoms were however common in PRKN-PD. Our findings on the relationship between the type of variant in PRKN and the phenotype of the disease may have implications for both genetic counselling and the design of precision clinical trials

Genotype-phenotype correlation in PRKN-associated Parkinson's disease

Bi-allelic pathogenic variants in PRKN are the most common cause of autosomal recessive Parkinson's disease (PD). 647 patients with PRKN-PD were included in this international study. The pathogenic variants present were characterised and investigated for their effect on phenotype. Clinical features and progression of PRKN-PD was also assessed. Among 133 variants in index cases (n = 582), there were 58 (43.6%) structural variants, 34 (25.6%) missense, 20 (15%) frameshift, 10 splice site (7.5%%), 9 (6.8%) nonsense and 2 (1.5%) indels. The most frequent variant overall was an exon 3 deletion (n = 145, 12.3%), followed by the p.R275W substitution (n = 117, 10%). Exon3, RING0 protein domain and the ubiquitin-like protein domain were mutational hotspots with 31%, 35.4% and 31.7% of index cases presenting mutations in these regions respectively. The presence of a frameshift or structural variant was associated with a 3.4 ± 1.6 years or a 4.7 ± 1.6 years earlier age at onset of PRKN-PD respectively (p &lt; 0.05). Furthermore, variants located in the N-terminus of the protein, a region enriched with frameshift variants, were associated with an earlier age at onset. The phenotype of PRKN-PD was characterised by slow motor progression, preserved cognition, an excellent motor response to levodopa therapy and later development of motor complications compared to early-onset PD. Non-motor symptoms were however common in PRKN-PD. Our findings on the relationship between the type of variant in PRKN and the phenotype of the disease may have implications for both genetic counselling and the design of precision clinical trials

Synthesis, Characterization, and Evaluation of Castor Oil-Based Acylated Derivatives as Potential Lubricant Base Stocks

Synthesis, characterization, and evaluation of a series of novel acylated derivatives of castor oil as biolubricant base stocks are described. The acylated derivatives of castor oil, castor oil fatty acid methyl and 2-ethylhexyl esters were synthesized using different anhydrides (C₁–C₆) in about 90–95% yield. All the products were structurally characterized using NMR and IR spectral data. The acylated products were evaluated for their physicochemical and lubricant properties. Although these products belong to group V, based on viscosity index (130–156), acylated derivatives of castor fatty acid alkyl esters belong to group III, the category of base fluids as per API classification. The acylated products exhibited excellent pour point (−21 to −39 °C) and flash point (174–280 °C). The hexanoylated and butanoylated esters of castor oil exhibited excellent flash points of 280 and 272 °C, respectively. The air release value was found to be excellent in the range of 0.38–0.99 min, and NOACK volatilities in the range of 3.25–3.92%. The other lubrication properties such as load carrying capacity, and emulsion stability were found to be good. Therefore, these derivatives will have utility in hydraulic and metal working fluids and other industrial fluids with their wide range of properties

Synthesis and evaluation of anti-oxidant and cytotoxic activities of novel 10-undecenoic acid methyl ester based lipoconjugates of phenolic acids

The synthesis of five novel methyl 10-undecenoate-based lipoconjugates of phenolic acids from undecenoic acid was carried out. Undecenoic acid was methylated to methyl 10-undecenoate which was subjected to a thiol–ene reaction with cysteamine hydrochloride. Further amidation of the amine was carried out with different phenolic acids such as caffeic, ferulic, sinapic, coumaric and cinnamic acid. All synthesized compounds were fully characterized and their structures were confirmed by spectral data. The anti-oxidant activity of the synthesized lipoconjugates of phenolic acids was studied by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and also by the inhibition of linoleic acid oxidation in micellar medium by differential scanning calorimetry (DSC). The prepared compounds were also screened for their cytotoxic activity against five cell lines. It was observed that the lipoconjugates of caffeic acid, sinapic acid, ferulic acid, and coumaric acid displayed anticancer and anti-oxidant properties. The anticancer properties of these derivatives have been assessed by their IC50 inhibitory values in the proliferation of MDA-MB231, SKOV3, MCF7, DU 145 and HepG2 cancer cell lines

Preparation and Properties of Lubricant Base Stocks from Epoxidized Karanja Oil and Its Alkyl Esters

Lubricant base stocks of epoxidized oil and its alkyl esters namely epoxidized karanja fatty acid methyl, butyl, 2-methyl-1-propyl, and 2-ethylhexyl esters were synthesized from renewable nonedible source karanja oil (<i>Pongamia glabra</i>). The reaction was carried out using peroxy formic acid (HCOOH) generated <i>in situ,</i> 30 wt % aqueous hydrogen peroxide (H₂O₂) by monitoring oxirane oxygen value. The optimized conditions to obtain epoxidized products were oil/ester: HCOOH: H₂O₂ (1:2:8/1:1.5:3 mol/mol/mol). The epoxidized products were obtained in 90–97% conversion by GC analysis. All the products were characterized by GC, GC-MS, IR, ¹H NMR spectral studies. The synthesized products were evaluated for physicochemical and lubricant properties. Based on viscosity index all the products belong to group III, category of base fluids as per API classification. Expecting pour point values that are on higher side, other lubrication properties such as viscosity, VI, flash point, Cu corrosion value, and air release value were found to be good

Novel Acyl Derivatives from Karanja Oil: Alternative Renewable Lubricant Base Stocks

Lubricant base stocks of acylated oil and its derivatives, namely, propionylated, butanoylated, and hexanoylated karanja oil and fatty acid methyl esters, were synthesized from renewable nonedible source karanja oil (Pongamia glabra). The reaction was carried out by Prilezhaev dihydroxylation, an in situ peroxyformic acid generated using hydrogen peroxide and formic acid. The hydroxylated derivatives were acylated with three acid anhydrides (C₃, C₄, and C₆). All of the synthesized products were examined for their purity by GC and GC-MS and characterized by IR and ¹H NMR spectral studies. The acylated derivatives were evaluated for physicochemical and lubricant properties. Propionylated and butanoylated esters of KFAME were found suitable as IS: 3098 hydraulic fluids in ISO VG 46 and ISO VG 68 categories, respectively. In addition, propionylated esters of KFAME are also suitable as IS: 8406 gear oils (R&O type). Other lubrication properties such as viscosity, viscosity index of all products belonging to group III, category of base fluids as per API classification, Cu corrosion value, weld point, and air release value were found to be good. These base stocks may find applications in hydraulic fluids and metal-working fluids