Cognitive-behavioural therapy for adult attention-deficit hyperactivity disorder: a proof of concept randomised controlled trial.

OBJECTIVE: To investigate efficacy, patient acceptability and feasibility of formulation-based cognitive-behavioural therapy (CBT) for adults with attention-deficit hyperactivity disorder (ADHD). NICE guidelines for adult ADHD recommend further research into psychological treatments. METHOD: Sixty participants with adult ADHD were randomly allocated to treatment as usual (TAU) vs. TAU plus up to 16 sessions of individual formulation-based CBT for ADHD. RESULTS: Adding formulation-based CBT to TAU for ADHD significantly improved ADHD symptoms on the Barkley Current Symptoms Scale and scores on the Work and Social Adjustment Scale. Adjusted effect sizes (ES) were 1.31 and 0.82 respectively. There were also significant improvements on secondary outcomes including independently evaluated clinical global improvement, self-rated anxiety, depression, global distress and patient satisfaction (adjusted effect sizes 0.52-1.01). CONCLUSIONS: This is the first randomised controlled trial to provide preliminary evidence of efficacy and acceptability of individual formulation-based CBT for ADHD when added to TAU over TAU alone. This approach now needs to be tested in a larger multicentred randomised controlled trial.

The effect of socioeconomic status on treatment and pregnancy outcomes in women with epilepsy in Scotland.

Compared to the background population, people with epilepsy tend to have lower rates of education and employment, lower rates of marriage and childbearing, and lower overall socioeconomic status (SES). Disparities in epilepsy care based on sociodemographic factors have been observed in the literature, but it is not known whether any such disparities exist in the UK. The UK Epilepsy and Pregnancy Register is a prospective, observational, registration and follow-up study that was set up to determine the relative safety of all AEDs taken in pregnancy. Here, we report outcomes of registered pregnancies to women with epilepsy living in Scotland from December 1996 to June 2012, based on the degree of socioeconomic deprivation of their postcode area. The Scottish Index of Multiple Deprivation (SIMD) quintile scores from 2006 were used to determine degree of socioeconomic deprivation, and group 1 (most deprived) and group 5 (least deprived) were compared. There were 1526 pregnancies with complete outcome data to women living in Scotland. Of these, 1453 (95.1%) resulted in a live birth and 68 (4.7%) had a major congenital malformation (MCM). Postcodes could not be reliably identified or verified for an additional three women, who have been excluded from SIMD group analysis. Of all women included in this study, 32.4% were in group 1 and 13.2% in group 5. No difference in MCM rate was observed between the two groups (4.4% in group 1 compared to 4.7% in group 5, p=0.84). Women in group 5 were more likely to take preconceptual folic acid (56.8% compared to 14.0%, relative risk: 4.1; 95% CI: 3.1-5.2) and less likely to have generalized tonic-clonic seizures in pregnancy (13.0% compared to 29.2%, relative risk: 0.4; 95% CI: 0.3-0.7) than those in group 1. Women in group 5 were more likely to be on monotherapy regimens (80.2% compared to 65.9%, relative risk: 1.2; 95% CI: 1.1-1.3), less likely to be on valproate (19.5% compared to 28.0%, p=0.05), and more likely to be on lower doses of the drug (825.9mg/day compared to 1012.0mg/day, p=0.05) compared to those in group 1. Although no change in MCM rate was seen based on SES, differences in treatment between socioeconomic groups do exist, particularly for preconceptual folic acid consumption, AED regimen, and seizure frequency. Greater emphasis on the importance of preconceptual counseling, both to discuss AED choice and folic acid intake, would be of benefit, particularly to those living in areas of high socioeconomic deprivation, to improve equity of healthcare delivery for women with epilepsy in Scotland.

Are Mental Health, Family and Childhood Adversity, Substance Use and Conduct Problems Risk Factors for Offending in Autism?

Mental health difficulties, family and childhood adversity factors, substance use and conduct problems have all been linked to offending behaviour in the general population. However, no large-scale study with comparison groups has investigated these risk factors in relation to autistic offenders. The current research included 40 autistic offenders, 40 autistic non-offenders, 40 typically developed (TD) offenders and 39 TD non-offenders. Conduct problems risk factors differentiated autistic offenders from both non-offender groups (autistic and TD) and mental health risk factors differentiated autistic offenders from both TD groups (offenders and non-offenders). Further research is required to understand more about the role of both conduct problems risk factors in autistic offenders (e.g., age at onset, frequency of behaviours) and the mental health needs of autistic offenders.

Severe statin-induced rhabdomyolysis mimicking Guillain-Barré syndrome in four patients with diabetes mellitus treated with fusidic acid.

BACKGROUND: An interaction between fusidic acid and HMG coenzyme A reductase inhibitors (statins), resulting in rhabdomyolysis, has been described. Pain and mild weakness are common presenting symptoms. CASE REPORT: We report four patients with Type 2 diabetes prescribed long-term statin treatment who, following treatment with fusidic acid, presented atypically with painless, severe flaccid paralysis suggestive of Guillain-Barré syndrome. This, together with nerve conduction studies consistent with Guillain-Barré syndrome, resulted in the delayed recognition of rhabdomyolysis in these cases. CONCLUSIONS: The addition of fusidic acid can precipitate rhabdomyolysis in patients with diabetes already taking a statin. This can present with rapidly progressive weakness resembling Guillain-Barré syndrome. We recommend that creatine kinase is checked in patients with diabetes on statin therapy who present with profound weakness and routinely in those commenced on prolonged courses of fusidic acid.

Self-reported motivations for engaging or declining to engage in cyber-dependent offending and the role of autistic traits.

Cyber-dependent offending, i.e. criminal behaviour reliant on computing and the online domain, has been reportedly associated with particular characteristics and motivations such as being young, male, autistic and motivated by challenge. These associations are anecdotal however and empirical evidence is limited. The present study investigated reasons for engaging or declining to commit cyber-dependent offending in cyber-skilled non-offenders (n = 175) and offenders (n = 7) via an online survey measuring cyber-dependent criminality. The potential role of autism and autistic traits was also considered. Qualitative interviews about motivations for offending were carried out with the offenders. The cyber-dependent offenders reported seven main reasons for engaging in cyber-dependent offending: (1) lack of understanding; (2) entertainment; (3) peer influence; (4) experience and career; (5) anonymity and risk perception; (6) life events; and (7) morals. Twenty-nine (approximately 17 %) of the non-offenders had been asked to engage in cyber-dependent offending but had declined. Their reasons and motivations for declining to commit cyber-dependent offences were compared with the cyber-dependent offenders reasons and motivations for engaging in cybercrime. Seven main reasons for declining to offend were identified: (1) moral principles; (2) perception of risk; (3) fear of consequences; (4) not wanting to; (5) wanting to adhere to the law; (6) behaviour being too complicated; and (7) price being too low. Implications for practise are discussed.

Folic acid use and major congenital malformations in offspring of women with epilepsy: a prospective study from the UK Epilepsy and Pregnancy Register.

OBJECTIVE: In the general population, folic acid supplementation during pregnancy has been demonstrated to reduce the frequency of neural tube defects (NTDs) and other major congenital malformations (MCMs). It is recommended that women with epilepsy contemplating pregnancy take supplemental folic acid because of the known antifolate effect of some antiepileptic drugs (AEDs). Here the aim was to determine the effectiveness of this practice. METHODS: This study is part of a prospective, observational, registration and follow-up study. Suitable cases are women with epilepsy who become pregnant and who are referred before outcome of the pregnancy is known. The main outcome measure is the MCM rate. Outcomes were analysed against folic acid exposure, malformation type and drug group for the most commonly used monotherapy AEDs. RESULTS: In 1935 cases reported to have received preconceptual folic acid, 76 MCMs (3.9%; 95% CI 3.1 to 4.9) and eight NTDs (0.4%; 95% CI 0.2 to 0.8) were identified. For 2375 women who were reported to have received folic acid but not until later in the pregnancy (n = 1825) or not at all (n = 550), there were 53 outcomes with an MCM (2.2%; 95% CI 1.7 to 2.9) and eight NTDs (0.34%; 95% CI 0.2 to 0.7). CONCLUSIONS: The study supports the view that extrapolation from studies carried out in the general population to groups of women with epilepsy may be questionable. It may be that the increased risk of MCM recorded in this group occurs through mechanisms other than that of folic acid metabolism.

Detecting seizure origin using basic, multiscale population dynamic measures: preliminary findings.

Many types of electrographic seizures are readily identifiable by direct visual examination of electroencephalographic or electrocorticographic recordings. This process can, however, be painstakingly slow, and much effort has been expended to automate the process using various dynamic properties of epileptiform waveforms. As methods have become more subtle and powerful they have been used for seizure subclassification, seizure prediction, and seizure onset identification and localization. Here we concentrate on the last, with reference to seizures of neocortical origin. We briefly review some of the methods used and introduce preliminary results from a very simple dynamic model based on key electrophysiological properties found in some seizure types: occurrence of very fast oscillations (sometimes called ripples), excess gamma frequency oscillations, electroencephalographic/electrocorticographic flattening, and changes in global synchrony. We show how this multiscale analysis may reveal features unique to seizure onset and speculate on the underlying cellular and network phenomena responsible.

Adapting Psychological Therapies for Autism - Therapist Experience, Skills and Confidence.

BACKGROUND: Psychological interventions informed by cognitive behavioural theory have proven efficacy in treating mild-moderate anxiety and depression. They have been successfully adapted for autistic children and adults who experience disproportionately high rates of co-occurring emotional problems. There has been little research into the perspectives and experience of psychological therapists adapting cognitive behavioural therapy (CBT) as part of routine clinical practice. We surveyed therapist skills, experience and confidence in working psychologically with autistic people, in order to highlight gaps and needs, as well as strengths in terms of therapist skills when working with this group. METHOD: Fifty therapists attending a training event completed a survey about their experience of adapting CBT for autistic clients, alongside a measure of therapist confidence. RESULTS: Almost all therapists reported making adaptations to CBT practice when working with autistic clients. Key challenges identified were rigidity in thinking and pacing sessions appropriately. Therapists were relatively confident about core engagement and assessment skills but reported less confidence in using their knowledge to help this group. Therapist confidence was not associated with years of practice or number of adaptations made, but was positively associated with level of therapy training received. CONCLUSIONS: This study highlights a need for training and ongoing supervision to increase therapist confidence in and ability to make appropriate adaptations to CBT treatment protocols for autistic people.

Inhibition of prolyl 4-hydroxylase decreases muscle fibrosis following chronic rotator cuff tear.

OBJECTIVES: Rotator cuff tears are among the most frequent upper extremity injuries. Current treatment strategies do not address the poor quality of the muscle and tendon following chronic rotator cuff tears. Hypoxia-inducible factor-1 alpha (HIF-1α) is a transcription factor that activates many genes that are important in skeletal muscle regeneration. HIF-1α is inhibited under normal physiological conditions by the HIF prolyl 4-hydroxylases (PHDs). In this study, we used a pharmacological PHD inhibitor, GSK1120360A, to enhance the activity of HIF-1α following the repair of a chronic cuff tear, and measured muscle fibre contractility, fibrosis, gene expression, and enthesis mechanics. METHODS: Chronic supraspinatus tears were induced in adult rats, and repaired 28 days later. Rats received 0 mg/kg, 3 mg/kg, or 10 mg/kg GSK1120360A daily. Collagen content, contractility, fibre type distribution and size, the expression of genes involved in fibrosis, lipid accumulation, atrophy and inflammation, and the mechanical properties of the enthesis were then assessed two weeks following surgical repair. RESULTS: At two weeks following repair, treatment groups showed increased muscle mass but there was a 15% decrease in force production in the 10 mg/kg group from controls, and no difference between the 0 mg/kg and the 3 mg/kg groups. There was a decrease in the expression of several gene transcripts related to matrix accumulation and fibrosis, and a 50% decrease in collagen content in both treated groups compared with controls. Additionally, the expression of inflammatory genes was reduced in the treated groups compared with controls. Finally, PHD inhibition improved the maximum stress and displacement to failure in repaired tendons. CONCLUSIONS: GSK1120360A resulted in improved enthesis mechanics with variable effects on muscle function. PHD inhibition may be beneficial for connective tissue injuries in which muscle atrophy has not occurred.Cite this article: J. P. Gumucio, M. D. Flood, A. Bedi, H. F. Kramer, A. J. Russell, C. L. Mendias. Inhibition of prolyl 4-hydroxylase decreases muscle fibrosis following chronic rotator cuff tear. Bone Joint Res 2017;6:57-65. DOI: 10.1302/2046-3758.61.BJR-2016-0232.R1.

Structure and mechanism of arylamine N-acetyltransferases.

Arylamine N-acetyltransferases (NATs) are a family of phase II drug-metabolising enzymes which are important in the biotransformation of various aromatic and heterocyclic amines and hydroxylamines, arylhydrazines and arylhydrazides. NATs are present in a wide range of eukaryotes and prokaryotes. Humans have two functional NAT isoforms, both of which are highly polymorphic. The pharmacogenetics of NATs is an area which has been extensively studied. The determination of the X-ray crystal structure of NAT from Salmonella typhimurium led to the identification of the catalytically essential triad of residues: Cys-His-Asp, which is present in all functional NAT enzymes. Recent co-crystallisation data and in silico docking studies of NAT from Mycobacterium smegmatis with substrates and inhibitors have aided the identification of important contact residues within the active site. The X-ray crystal structures of four prokaryotic NAT proteins have now been determined, and these have been used to generate structural models of eukaryotic NATs, providing valuable insight into their active-site architecture. In addition to aiding crystallographic experiments, recent progress in the production of recombinant prokaryotic and eukaryotic NATs has allowed comparative studies of the kinetics and activity profiles of these enzymes. In this review we present an overview of recent structural and activity studies on NAT enzymes, and we outline how in silico methods may be used to predict NAT protein-ligand interactions based on the current knowledge.

Identification of a human HECT family protein with homology to the Drosophila tumor suppressor gene hyperplastic discs.

Use of the differential display technique to isolate progestin-regulated genes in T-47D human breast cancer cells led to identification of a novel gene, EDD. The cDNA sequence contains a 2799 amino acid open reading frame sharing 40% identity with the predicted 2894 amino acid product of the Drosophila melanogaster tumor suppressor gene hyperplastic discs, while the carboxy-terminal 889 amino acids show 96% identity to a rat 100 kDa HECT domain protein. EDD mRNA was progestin-induced in T-47D cells and was highly abundant in testes and expressed at moderately high levels in other tissues, suggesting a broad role for EDD. Anti-EDD antibodies immunoprecipitated an approximately 300 kDa protein from T-47D cell lysates. HECT family proteins function as E3 ubiquitin-protein ligases, targeting specific proteins for ubiquitin-mediated proteolysis. EDD is likely to function as an E3 as in vitro translated protein bound ubiquitin reversibly through a conserved HECT domain cysteine residue. EDD was localized by FISH to chromosome 8q22, a locus disrupted in a variety of cancers. Given the homology between EDD and the hyperplastic discs protein, which is required for control of imaginal disc growth in Drosophila, EDD potentially has a role in regulation of cell proliferation or differentiation.

Electrostatic effects on modification of charged groups in the active site cleft of subtilisin by protein engineering.

The dielectric constant in the active site cleft of subtilisin from Bacillus amyloliquefaciens has been probed by mutating charged residues on the rim and measuring the effect on the pKa value of the active site histidine (His64) by kinetics. Mutation of a negatively charged surface residue, which is 12 to 13 A from His64, to an uncharged one Asp----Ser99) lowers the pKa of the histidine by up to 0.4 unit at low ionic strength (0.005 to 0.01 M). This corresponds to an apparent dielectric constant of about 40 to 50 between Asp99 and His64. The mutation is in an external loop that is known to tolerate a serine at position 99 from homologies with subtilisins from other bacilli. The environment between His64 and Asp99 is predominantly protein. Another charged residue that is at a similar distance from His64 (14 to 15 A) and is also in an external loop that is known to tolerate a serine residue is Glu156, at the opposite side of the active site. There is only water in a direct line between His64 and Glu156. Mutation of Glu----Ser156 also lowers the pKa of His64 by up to 0.4 unit at low ionic strength. This change again corresponds to an apparent dielectric constant of about 40 to 50. The pKa values were determined from the pH dependence of kcat/KM for the hydrolysis of peptide substrates, with a precision of typically +/- 0.02 unit. The following suggests that the changes in pKa are real and not artefacts of experimental conditions: Hill plots of the data for pKa determination have gradients (h) of -1.00(+/- 0.02), showing that there are negligible systematic deviations from theoretical ionization curves involving a monobasic acid: the pH dependence for the hydrolysis of two different substrates (succinyl-L-alanyl-L-alanyl-L-prolyl-L-phenylalanyl p-nitroanilide and benzoyl-L-valyl-L-glycyl-L-arginyl p-nitroanilide) gives identical results so that the pKa is independent of substrate; the pH dependence is unaffected by changing the concentration of enzyme, so that aggregation is not affecting the results; the shift in pKa is masked by high ionic strength, as expected qualitatively for ionic shielding of electrostatic interactions.

Gender differences in psychogenic non-epileptic seizures.

PURPOSE: To determine whether male and female populations of patients with psychogenic non-epileptic seizures (PNES) are similar, in terms of demographic and social factors, aetiological factors, the clinical characteristics of events and path to diagnosis. METHODS: Prospective study by semi-structured interview of 160 consecutive patients (117 female and 43 male) with video EEG confirmed diagnosis of PNES + epileptic seizures (ES). RESULTS: Most parameters showed no significant differences. Males were, however, more likely to be unemployed (P = 0.028), and females were six times more likely to self-harm (P = 0.050), though the numbers were small in these categories. Men were more likely to attribute their PNES to a predisposing factor for epilepsy (P = 0.001), and women were over eight times more likely to report sexual abuse (P = 0.001). Event semiology was similar, but women were more likely to weep after events (P = 0.017). The carers and family of men with PNES were three times less likely to accept the diagnosis of PNES (P = 0.017). CONCLUSIONS: Our samples showed few significant gender differences, suggesting that other male and female populations of patients with PNES are likely to be similar also. Some of the differences we found may give insight into causation of PNES.

Schizophrenia and the myth of intellectual decline.

OBJECTIVE: The authors' goal was to investigate the issue of intellectual deterioration in schizophrenia. METHOD: They examined the childhood IQs of adult patients with schizophrenia who had attended a child psychiatry service where measurement of intelligence was routine. Follow-up IQs of 34 of these patients were obtained an average of 19.4 years later. RESULTS: The mean child and adult IQs were greater than one standard deviation lower than those of the general population. There were no significant differences between the child and adult IQs, however, suggesting that the impairment in intelligence during childhood was stable over the follow-up period. CONCLUSIONS: The deficit in intellectual function observed in these patients, and reported in the literature, is lifelong and predates the onset of schizophrenia.

Mutation in the human gene for 3 beta-hydroxysteroid dehydrogenase type II leading to male pseudohermaphroditism without salt loss.

A 5-year-old XY pseudohermaphrodite was found to have a defect of steroid biosynthesis consistent with a partial deficiency of the enzyme 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD). Circulating concentrations of delta 5 steroids and delta 5 urinary steroid metabolites were elevated and remained elevated after orchidectomy. There was no evidence of salt loss, plasma renin being within normal limits, and no detectable glucocorticoid abnormality. The coding sequences of the genes for 3 beta-HSD types I and II were amplified by PCR and screened for mutations by denaturing gradient gel electrophoresis (DGGE) and manual and automatic DNA sequencing. A mutation in the gene for 3 beta-HSD type II was observed at codon 173 (CTA-->CGA), leading in the affected patient to a homozygous substitution in which the leucine at residue 173 was altered to an arginine (L173R). The propositus's 2-year-old XX sister was also homozygous for L173R and showed the biochemical characteristics of partial 3 beta-HSD deficiency without clinical symptoms or signs. The mutation segregated as an autosomal recessive. Three related heterozygous adult females showed evidence of a small over-production of delta 5 steroids and steroid metabolites and a variable reduction in ovarian function. Concentrations of delta 5 steroids and steroid metabolites in the heterozygous father of the propositus were within the normal range. These data are discussed in relation to the endocrine causes of pseudohermaphroditism and hirsutism. Evidence for tight linkage between the genes for 3 beta-HSD types I and II was obtained using a microsatellite polymorphism in the third intron of the gene for 3 beta-HSD type II and synonymous and non-synonymous mutations and polymorphisms in the gene for 3 beta-HSD type I. The latter polymorphisms were located 88 bp apart at the 3' end of the type I coding sequence and could be physically resolved as haplotypes using DGGE. The application of DGGE to the analysis of mutations in members of a multigene family is discussed.

The human 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) gene cluster on chromosome 1p13 contains a presumptive pseudogene; 3 beta-HSD and CYP17 do not segregate with dominantly inherited hirsutism.

Four hirsute females from a family exhibiting idiopathic dominant hirsutism were examined. Basal blood levels of delta 5 and delta 4 steroids were within the normal range, but ACTH stimulation led to increases in 17-hydroxypregnenolone and dehydroepiandrosterone that were significantly above control levels. Using polymorphic genetic markers, the genes for cytochrome P450c1717 encoded by CYP17, and the type I and II forms of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) were found not to segregate with hirsutism in this family, though a base substitution was detected in the 3' end of exon 1 of the gene for 3 beta-HSD type I in three of the four patients investigated. Analysis of PCR patients amplification products by denaturing gradient gel electrophoresis (DGGE) and sequencing revealed a novel homologue of exon 3 of 3 beta-HSD. DNA of one of the affected patients was used to create a genomic library in lambda gem 11 and clones containing the novel homologue were obtained and partially sequenced. The equivalent clone was obtained from a genomic library of an unrelated normal individual. The sequences of the clones from patient and control were identical and homologous to exons 2-4 of human 3 beta-HSD types I and II. No difference was found in the PCR primer sites that flanked the exons 3 homologue which led to its detection on DGGE gels. In both clones, stop codons and deletions were identified in the exon 4 homologue, leading to the deduction that the sequence comes from a pseudogene, which we call 3 beta-HSD psi 1. The pseudogene mapped to chromosome 1p13. It was concluded that dominantly inherited idiopathic hirsutism in this rare kindred was not due to deficiencies in 3 beta-HSD types I, II, or psi or of CYP17).

Phenotypic variability and origins of mutations in the gene encoding 3beta-hydroxysteroid dehydrogenase type II.

Mutations in HSD3B2, the gene for 3beta-hydroxysteroid dehydrogenase type II (3beta-HSD II) have been detected and activities analysed through the in vitro expression of mutant cDNAs. Two full sibs with male pseudohermaphroditism were found to be double heterozygotes: N100S/266DeltaA. This genotype leads to the most profound loss of 3beta-HSD II enzyme activity (1.3% of normal) described to date in cases without severe salt-loss. One sib (N100S/266DeltaA) is the first reported male case of type II deficiency affected with premature adrenarche. Three apparently independent kindreds had propositi affected with the HSD3B2 mutation A82T/A82T, which is associated with a non salt-losing phenotype with variable expressivity in females. These three families had the same extended HSD3B haplotype and are likely to have inherited the same ancestral mutation. The significance of this finding is discussed in the light of the presence of A82T mutation at a homologous position in pseudogene varphi5 that is present in the HSD3B cluster.

Mutation in 3 beta-hydroxysteroid dehydrogenase type II associated with pseudohermaphroditism in males and premature pubarche or cryptic expression in females.

A mutation (A82T) is described in the coding sequence of the gene for 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) type II that is associated with variable clinical consequences. Four homozygotes are described, all of which showed elevated levels of delta 5 steroids consistent with 3 beta-HSD deficiency. Two males from a consanguineous family were found to be homozygous for A82T and were affected with pseudohermaphroditism. They differed in their degree of mild salt loss. In the same family a female was found to be homozygous for A82T, but was clinically normal and had no history of premature pubarche or of abnormal menstrual cycles. However, in an apparently unrelated family, the A82T mutation was found in a female affected with premature pubarche. This is the first report of a proven mutation in 3 beta-HSD type II associated with premature pubarche.

Light-induced tailoring of PEG-hydrogel properties.

We have previously reported (Andreopoulos et al. J Am Chem Soc 118 (1996) 6235-6240) the synthesis of hydrogels via the photopolymerization of water-soluble PEG molecules. In this paper, PEG-hydrogel membranes were prepared by the irradiation (> 300 nm) of aqueous solutions of photosensitive 4-armed PEG (nominal molecular weight of 20000), in the absence of photo-initiators. The hydroxyl termini of the PEG's were functionalized with cinnamylidene acetate groups to form photosensitive PEG macromers (PEG-CA), which upon irradiation (>300 nm) formed crosslinks between adjacent cinnamylidene groups resulting in highly crosslinked networks (hydrogels) (Andreopoulos et al. J Am Chem Soc 118 (1996) 6235-6240). The hydrogel membranes were highly swellable with equilibrium volume fractions ranging from 0.02 to 0.05. Their swellability was a function of irradiation light (>300 nm) and degree of modification of the PEG molecules. The effect of light on the permeation fluxes of myoglobin (Mb), hemoglobin (Hb), and lactate dehydrogenase-L (LDH) through PEG membranes was also assessed and the diffusion coefficients of the proteins were determined accordingly. The PEG-CA membranes exhibited photoscissive behavior upon exposure to UV irradiation (254 nm). Therefore, UV light was used as a trigger to control the mesh size of the membranes, and thereby the permeation fluxes of Mb, Hb, and LDH. Equilibrium swelling experiments with membranes prepared under different irradiation conditions were performed, and the Flory-Huggins model was utilized to determine the mesh size and the average molecular weight between crosslinks of the synthesized hydrogels.

Treatment of rat pancreatic islets with reactive PEG.

Covalent attachment of polymers to cells and tissues could be used to solve a variety of problems associated with cellular therapies. Insulin-dependent diabetes mellitus is a disease resulting from the autoimmune destruction of the beta cells of the islets of Langerhans in the pancreas. Transplantation of islets into diabetic patients would be an attractive form of treatment, provided that the islets could be protected from the host's immune system in order to prevent graft rejection. If reaction of polyethylene glycol (PEG) segments with the islet surface did not damage function, the immunogenicity and cell binding characteristics of the islet could be altered. To determine if this process damages islets, rat islets have been isolated and treated with protein-reactive PEG-isocyanate (MW 5000) under mild reaction conditions. An assessment of cell viability using a colorimetric mitochondrial activity assay showed that treatment of the islets with PEG-isocyanate did not reduce cell viability. Insulin release in response to secretagogue challenge was used to evaluate islet function after treatment with the polymer. The insulin response of the PEG-treated islets was not significantly different than untreated islets in a static incubation secretagogue challenge. In addition, PEG-isocyanate-treated islets responded in the same manner as untreated islets in a glucose perifusion assay. Finally, the presence of PEG on the surface of the islets after treatment with the amine-reactive N-hydroxysuccinimide-PEG-biotin (not PEG-isocyanate) was confirmed by indirect fluorescence staining. These results demonstrate the feasibility of treating pancreatic islets with reactive polymeric segments and provide the foundation for further investigation of this novel means of potential immunoisolation.