Topical antiangiogenic SRPK1 inhibitors reduce choroidal neovascularization in rodent models of exudative AMD

PURPOSE

Exudative AMD (wet AMD) is treated by monthly injection into the eye of anti-VEGF proteins. VEGF is alternatively spliced to produce numerous isoforms that differ in angiogenic activity. Serine-rich protein kinase-1 (SRPK1) has been identified as a regulator of pro-angiogenic VEGF splicing by phosphorylating serine-rich splicing factor-1 (SRSF1), which binds to VEGF pre-mRNA. We tested the hypothesis that topical (eye drop) SRPK1-selective inhibitors could be generated that reduce pro-angiogenic isoforms, and prevent choroidal neovascularization in vivo.

METHODS

Novel inhibitors were tested for SRPK inhibition in vitro, pro-angiogenic VEGF production in RPE cells by PCR and ELISA, and for inhibition of choroidal neovascularisation in mice and rats.

RESULTS

A novel disubstituted furan inhibitor was selective for the SRPK family of kinases and reduced expression of pro-angiogenic but not antiangiogenic VEGF isoforms. This inhibitor and previously identified SRPK inhibitors significantly reduced choroidal neovascularisation in vivo. Topical administration of SRPK inhibitors dose-dependently blocked CNV with an EC50 of 9 μM.

CONCLUSIONS

These results indicate that novel SRPK1 selective inhibitors could be a potentially novel topical (eye drop) therapeutic for wet AMD.

Use of environmental manipulation and classroom and modified informal reality orientation with institutionalized, confused elderly patients

The effectiveness of 'classroom' reality orientation (CRO) for confused elderly subjects was evaluated. Experimental groups 1 and 2 (each consisting of five subjects) received CRO for 1 month with only group 1 continuing with maintenance CRO for a further 2 months. Both experimental groups and the control group (10 subjects) received modified informal reality orientation (IRO) and environmental manipulation (EM) for all 3 months. All subjects were assessed prior to the start of the study and after 4 and 12 weeks of treatment on cognitive and behavioural measures. Both experimental groups showed significant improvement on both cognitive and behavioural measures after 1 month compared with the controls. This improvement was maintained at 12 weeks for both experimental groups but there was a statistically significant difference only between group 1 and its matched controls.

Catalytic role of the C-terminal domains of a fungal non-reducing polyketide synthase

The in vivo activity of truncated forms of methylorcinaldehyde synthase shows that the synthase retains a hydrolytic release activity in the absence of reductive chain release and that chain-length is not controlled by the reductive release domain; experiments using a methyltransferase inhibitor suggest that methylation occurs prior to aromatisation.

Use of environmental manipulation and modified informal reality orientation with institutionalized, confused elderly subjects: a replication

The effectiveness, for confused elderly subjects, of modified informal reality orientation and environmental manipulation without any 'classroom' reality orientation was investigated with 10 experimental subjects in one ward and 10 control subjects in another. All subjects were assessed prior to the start of the intervention and after 6 and 12 weeks of treatment on cognitive and behavioural measures. While the control group showed decline on all measures except one, the experimental group improved in ward orientation and cognitive status and showed no decline on the behavioural measures.

Substrate selectivity of an isolated enoyl reductase catalytic domain from an iterative highly reducing fungal polyketide synthase reveals key components of programming

A cis-acting enoyl reductase (ER) catalytic domain was isolated from a fungal highly reducing iterative polyketide synthase (HR-iPKS) for the first time and studied in vitro. The ER from the squalestatin tetraketide synthase forms a discrete dimeric protein in solution. The ER shows broad substrate selectivity, reducing enoyl species including both natural and unnatural substrates. Pantetheine-bound substrate thiolesters reacted much faster than the corresponding SNAC thiolesters. The unnatural substrates included Z-olefins, 2-ethyl olefins and pentaketides. Methylation of the substrate modifies the activity of the ER such that the 2,4-dimethyl oct-2-enoyl substrate fits into the active site but cannot be reduced. A new NMR-based assay was developed for the direct observation of the stereochemical preferences at the 4' position of the NADPH cofactor and the C-2 and C-3 positions of the substrates. The assay reveals that the fungal iPKS ER-catalysed reaction is stereochemically identical to that of the vertebrate FAS (vFAS) at the cofactor 4' position and the substrate 3-position, but the high stereoselectivity displayed by intact SQTKS is lost such that reprotonation at the 2-position is unselective by the isolated ER. A 3D model of ER was consistent with these observations and showed that the ER may sequester its final substrate to prevent further chain extension. The results support a developing model for programming by HR-iPKS in which competition for substrates between restrictive and permissive catalytic domains chaperones the growing polyketide to completion, while allowing for errors and evolution.

Assessing memory deterioration with the Wechsler Memory Scale, the National Adult Reading Test, and the Schonell Graded Word Reading Test

The National Adult Reading Test (NART), the Schonell Graded Word Reading Test (SGWRT), and the Wechsler Memory Scale, Form I (WMS) were administered to 65 healthy subjects aged 65 to 89 years. Regression equations were derived which allowed total raw score on the WMS to be predicted from the subject's age and from the number of errors on the NART alone or on the NART and SGWRT combined. The distribution of discrepancies between obtained and predicted WMS scores for each equation did not depart significantly from normality and the percentage of subjects at each discrepancy score is provided. The standard error of prediction for each equation is slightly less than that for predicting WAIS IQ from the NART. Sixteen patients with clinical diagnoses of senile dementia of the Alzheimer type obtained discrepancies as large or larger than the most discrepant 2% of normal subjects. These results suggest that this procedure may provide a brief but effective assessment of cognitive deterioration in the elderly and may be capable of assessing dementia earlier than the NART/WAIS combination.

In vitro kinetic study of the squalestatin tetraketide synthase dehydratase reveals the stereochemical course of a fungal highly reducing polyketide synthase

Six potential diketide substrates for the squalestatin tetraketide synthase (SQTKS) dehydratase (DH) domain were synthesised as N-acetyl cysteamine thiolesters (SNAC) and tested in kinetic assays as substrates with an isolated DH domain. 3R-3-hydroxybutyryl SNAC 3R-16 was turned over by the enzyme, but its enantiomer was not. Of the four 2-methyl substrates only 2R,3R-2-methyl-3-hydroxybutyryl SNAC 2R,3R-8 was a substrate. Combined with stereochemical information from the isolated SQTKS enoyl reductase (ER) domain, our results provide a near complete stereochemical description of the first cycle of beta-modification reactions of a fungal highly reducing polyketide synthase (HR-PKS). The results emphasise the close relationship between fungal HR-PKS and vertebrate fatty acid synthases (vFAS).

Anna Thompson and the American liner New York: some normative data

Increased proactive inhibition is claimed to be common in brain-damaged subjects and the Wechsler Memory Scale is often used in the clinical examination of such subjects. Normative data are presented on the two paragraphs of the Logical Memory sub-test of the WMS, Form 1, which allow evaluation of the frequency of occurrence of a discrepancy of a given size between performances on the two paragraphs, based on the performances of 500 subjects without any known neuropsychiatric involvement.

Paired associate learning: normative data for differences between high and low associate word pairs

Wilson, Bacon, Kaszniak, and Fox (1982) suggest that the learning of low associate pairs on the Wechsler Memory Scale involves episodic memory alone while the learning of high associate pairs involves semantic memory as well. Tulving (1983) also comments that, whereas some information in episodic memory is relatively unorganized and access to its content tends to be deliberate and requiring conscious effort (e.g., low associate pairs), information in semantic memory is organized and access to its content is more automatic (e.g., high associate pairs). As there may be occasions when it would be useful to compare these two types of memory functioning, differential diagnosis between depressive pseudodementia and organic dementia for example, normative data is provided enabling the calculation of the frequency with which differences between the learning of the two kinds of associate occur, based on the performance of 500 subjects with no known neuropsychiatric involvement.

Structural and mechanistic studies of the orf12 gene product from the clavulanic acid biosynthesis pathway

Structural and biochemical studies of the orf12 gene product (ORF12) from the clavulanic acid (CA) biosynthesis gene cluster are described. Sequence and crystallographic analyses reveal two domains: a C-terminal penicillin-binding protein (PBP)/β-lactamase-type fold with highest structural similarity to the class A β-lactamases fused to an N-terminal domain with a fold similar to steroid isomerases and polyketide cyclases. The C-terminal domain of ORF12 did not show β-lactamase or PBP activity for the substrates tested, but did show low-level esterase activity towards 3'-O-acetyl cephalosporins and a thioester substrate. Mutagenesis studies imply that Ser173, which is present in a conserved SXXK motif, acts as a nucleophile in catalysis, consistent with studies of related esterases, β-lactamases and D-Ala carboxypeptidases. Structures of wild-type ORF12 and of catalytic residue variants were obtained in complex with and in the absence of clavulanic acid. The role of ORF12 in clavulanic acid biosynthesis is unknown, but it may be involved in the epimerization of (3S,5S)-clavaminic acid to (3R,5R)-clavulanic acid.

Structural and biochemical analyses reveal how ornithine acetyl transferase binds acidic and basic amino acid substrates

Structural and biochemical analyses reveal how ornithine acetyl-transferases catalyse the reversible transfer of an acetyl-group from a basic (ornithine) to an acidic (glutamate) amino acid by employing a common mechanism involving an acetyl-enzyme intermediate but using different side chain binding modes.

Paired associate learning: form 1 and form 2 of the Wechsler Memory Scale

Despite its popularity as a clinical measure, the paired Associate Learning (PAL) subtest of Wechsler's Memory Scale (WMS) still remains relatively undocumented for its psychometric properties. This article reports on the performance of 500 (form 1) and 600 (form 2) general medical patients hospitalized for other than neuropsychiatric conditions across five (20-69) and six (20-79) ten-year age bands respectively. In both alternate forms of PAL, strong age effects emerged while sex differences were more marked in form 2. Temporal reliability, assessed in separate student samples, proved adequate for either form. Parallel form correlations also indicated a moderate relationship between them. When easy and hard associates were analysed as separate measures with MANOVA the two forms were found to differ. Some possible reasons for these results are explored with respect to current information processing concepts postulated to affect verbal learning performance, and their utility in helping distinguish between pseudodementia and mild Alzheimer type dementia. Separate factor analyses also showed the two equivalent forms to diverge somewhat in their structural pattern with form 1 demonstrating clear clusterings of the pairs along a continuum ranging from very easy (overlearned) and mediate (superordinate) to hard associates.