76
|
Duncan R, Oto M, Russell AJC, Conway P. Pseudosleep events in patients with psychogenic non-epileptic seizures: prevalence and associations. J Neurol Neurosurg Psychiatry 2004; 75:1009-12. [PMID: 15201361 PMCID: PMC1739122 DOI: 10.1136/jnnp.2003.022632] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVES To determine the prevalence and clinical associations of a history of events during sleep in patients with psychogenic non-epileptic seizures (PNES, pseudoseizures), and to compare the prevalence of a history of sleep events with that in poorly controlled epilepsy. METHODS Prospective study by semistructured interview of the history of event patterns and their clinical associations in 142 patients with video EEG confirmed PNES, and 100 patients with poorly controlled epilepsy. RESULTS 84/142 patients with PNES (59%) and 47/100 with epilepsy (47%) gave a history of events during sleep (p = 0.062). In patients with PNES, significant associations were found between a history of sleep events and: convulsive clinical semiology, antiepileptic drug treatment, fatigue, suicide attempts, mood disorder, and physical abuse. A particularly strong association with social security benefit was also found (odds ratio 4.0, p<0.001). CONCLUSIONS The prevalence of a history of sleep events is similar in PNES and epilepsy, and is of no value in discriminating between the two, although a history of events occurring exclusively during sleep does suggest epileptic seizures. The clinical associations found indicate that a combination of psychopathological and external influences may be important in determining whether or not a patient with PNES gives a history of events during sleep.
Collapse
|
77
|
Griffiths PC, Paul A, Khayat Z, Wan KW, King SM, Grillo I, Schweins R, Ferruti P, Franchini J, Duncan R. Understanding the Mechanism of Action of Poly(amidoamine)s as Endosomolytic Polymers: Correlation of Physicochemical and Biological Properties. Biomacromolecules 2004; 5:1422-7. [PMID: 15244460 DOI: 10.1021/bm049936g] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Bioresponsive poly(amidoamine)s (PAA)s are currently under development as endosomolytic polymers for intracellular delivery of proteins and genes. Here for the first time, small-angle neutron scattering (SANS) is used to systematically investigate the pH-dependent conformational change of an endosomolytic polymer, the PAA ISA 23. The radius of gyration of the ISA23 was determined as a function of pH and counterion, the aim being to correlate changes in polymer conformation with membrane activity assessed using a rat red blood cell haemolysis assay. With decreasing pH, the ISA23 radius of gyration increased to a maximum (R(g) approximately 80 A) around pH = 3, before subsequently decreasing once more. At high pH and therefore high ionic strengths, the polymer is negatively charged and adopts a rather compact structure (R(g) approximately 20 A), presumably with the dissociated carboxylic groups on the exterior of the polymer coil. At low pH, the coil again collapses (R(g) < 20 A), presumably due to the effects of the high ionic strength. It is concluded that the nature of the salt form has no direct bearing on the size of the polymer coil, but it does indirectly determine the prevailing pH and, hence, polymer conformation. Pulsed-gradient spin-echo NMR measurements were in good agreement with the SANS estimates of the radius of gyration, although ISA23 polydispersity does complicate the data interpretation/comparison. These results support the proposed mode of action of PAAs, namely a coil expansion on passing from a neutral pH (extracellular) to an acidic pH (endosomal and lysosomal) environments. The results do, however, suggest that the charge on the polymer shows a closer correlation with the haemolysis activity rather than the polymer conformation.
Collapse
|
78
|
McGonigal A, Russell AJC, Mallik AK, Oto M, Duncan R. Use of short term video EEG in the diagnosis of attack disorders. J Neurol Neurosurg Psychiatry 2004; 75:771-2. [PMID: 15090577 PMCID: PMC1763561 DOI: 10.1136/jnnp.2003.024893] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Distinguishing epileptic from psychogenic non-epileptic seizures (PNES) often requires video electroencephalography (EEG) recording. Inpatient recording is a limited resource; some evidence suggests that short term video EEG (SVEEG) is useful, but its role in practice has yet to be evaluated. OBJECTIVE To assess the usefulness of SVEEG in the diagnosis of attack disorders. METHODS One hundred and forty three SVEEG recordings were performed during an 18 month period. RESULTS A diagnostic event was recorded in 72 of 143 (50.3%): PNES (n = 51), epilepsy (n = 7), or other attacks, such as movement disorders (n = 14). CONCLUSIONS SVEEG is a robust and useful diagnostic technique, which complements existing resources.
Collapse
|
79
|
Espie CA, Watkins J, Curtice L, Espie A, Duncan R, Ryan JA, Brodie MJ, Mantala K, Sterrick M. Psychopathology in people with epilepsy and intellectual disability; an investigation of potential explanatory variables. J Neurol Neurosurg Psychiatry 2003; 74:1485-92. [PMID: 14617702 PMCID: PMC1738251 DOI: 10.1136/jnnp.74.11.1485] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
OBJECTIVES There are few studies on epilepsy and psychopathology in people with intellectual disability (mental retardation) despite epilepsy prevalence rates that are thirty times higher than in the general population. The aims of this study, therefore, were to identify reliable, epilepsy-specific predictors of psychiatric and behavioural disorder in these patients, and to investigate reliable predictors of carer stress. METHODS A database of 685 patients was compiled, from which 250 were randomly selected. Structured interviews were completed on 186 of these 250 patients (74%) (108 men, 78 women; mean age (SD) 35.5 (10.1)) comprising descriptive, clinical and functional components, and validated measures of psychopathology for which comparative data were available. Logistic and linear regression methods were used to identify predictors. RESULTS One-third of patients with epilepsy and intellectual disability met criteria for possible psychiatric disorder, particularly affective/neurotic disorder; twice the comparison rates for intellectual disability alone. Behavioural problem levels, however, were lower than population norms. Regression models explaining modest amounts of variance (R(2)< or =24%) suggested certain seizure phenomena (greater seizure severity, more seizures in past month, lesser tendency to loss of consciousness during seizures) as particular risk factors for psychiatric disorder. General disability factors such as level of intellectual, sensory or motor disability and side effects of medication, however, contributed more to explaining behavioural problems. Around half of the family carers reported significant stress, and one-third exhibited clinically significant anxiety symptoms. Younger carers were more stressed, and side effects from patients' medication also contributed to carer stress. CONCLUSIONS Although epilepsy in itself may be a risk factor for psychopathology in a minority of people with intellectual disability, some epilepsy-specific factors may predict psychiatric disorder. Behavioural problems need to be considered separately from psychiatric disorder because general factors, more closely associated with disability, are stronger predictors of their occurrence.
Collapse
|
80
|
Oto M, Russell AJC, McGonigal A, Duncan R. Misdiagnosis of epilepsy in patients prescribed anticonvulsant drugs for other reasons. BMJ 2003; 326:326-7. [PMID: 12574049 PMCID: PMC1125187 DOI: 10.1136/bmj.326.7384.326] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
81
|
Duncan R. Many universities do teach professionalism. BRITISH JOURNAL OF NURSING (MARK ALLEN PUBLISHING) 2002; 11:1297. [PMID: 12481763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
|
82
|
Stephens S, Beyer B, Balthazar-Stablein U, Duncan R, Kostacos M, Lukoma M, Green GR, Poccia D. Two kinase activities are sufficient for sea urchin sperm chromatin decondensation in vitro. Mol Reprod Dev 2002; 62:496-503. [PMID: 12112583 DOI: 10.1002/mrd.90005] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Decondensation of compact and inactive sperm chromatin by egg cytoplasm at fertilization is necessary to convert the male germ cell chromatin to an active somatic form. We studied decondensation of sea urchin sperm nuclei in a cell-free extract of sea urchin eggs to define conditions promoting decondensation. We find that egg cytosol specifically phosphorylates two sperm-specific (Sp) histones in vitro in the same regions as in vivo. This activity is blocked by olomoucine, an inhibitor of cdc2-like kinases, but not by chelerythrine, an inhibitor of protein kinase C (PKC). PKC phosphorylates and solubilizes the sperm nuclear lamina, one requirement for decondensation. Olomoucine, which does not inhibit lamina removal, blocks sperm nuclear decondensation in the same concentration range over which it is effective in blocking Sp histone phosphorylation. In a system free of other soluble proteins, neither PKC nor cdc2 alone elicit sperm chromatin decondensation, but the two act synergistically to decondense sperm nuclei. We conclude that two kinases activities are sufficient for sea urchin male pronuclear decondensation in vitro, a lamin kinase (PKC) and a cdc2-like Sp histone kinase.
Collapse
|
83
|
McGonigal A, Oto M, Russell AJC, Greene J, Duncan R. Outpatient video EEG recording in the diagnosis of non-epileptic seizures: a randomised controlled trial of simple suggestion techniques. J Neurol Neurosurg Psychiatry 2002; 72:549-51. [PMID: 11909925 PMCID: PMC1737844 DOI: 10.1136/jnnp.72.4.549] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVE To assess the yield of recorded habitual non-epileptic seizures during outpatient video EEG, using simple suggestion techniques based on hyperventilation and photic stimulation. DESIGN Randomised controlled trial of "suggestion" v "no suggestion" during outpatient video EEG recording. SETTING Regional epilepsy service (tertiary care; single centre). PARTICIPANTS 30 patients (22 female, 8 male), aged over 16 years, with a probable clinical diagnosis of non-epileptic seizures; 15 were randomised to each group. MAIN OUTCOME MEASURES Yield of habitual non-epileptic seizures recorded, and requirement for additional inpatient video EEG. RESULTS 10/15 patients had habitual non-epileptic seizures with suggestion; 5/15 had non-epileptic seizures with no suggestion (p = 0.058; NS); 8/9 patients with a history of previous events in medical settings had non-epileptic seizures recorded during study. Logistic regression analysis with an interaction clause showed a significant effect of suggestion in patients with a history of previous events in medical settings (p = 0.003). An additional inpatient video-EEG was avoided in 14 of the 30 patients (47%). CONCLUSIONS Habitual non-epileptic seizures can be recorded reliably during short outpatient video EEG in selected patients. Simple (non-invasive) suggestion techniques increase the yield at least in the subgroup with a history of previous events in medical settings. Inpatient video EEG can be avoided in some patients.
Collapse
|
84
|
Richardson SC, Pattrick NG, Man YK, Ferruti P, Duncan R. Poly(amidoamine)s as potential nonviral vectors: ability to form interpolyelectrolyte complexes and to mediate transfection in vitro. Biomacromolecules 2002; 2:1023-8. [PMID: 11710005 DOI: 10.1021/bm010079f] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Poly(amidoamine)s (PAAs) are water-soluble polymers that display pH-dependent membrane activity. PAAs have the potential to act as a synthetic alternative to fusogenic peptides and thus promote endosomal escape. The purpose of this study was to investigate for the first time whether PAA have the ability to complex DNA, protect it from nuclease degradation and to promote transfection in vitro. PAAs ISA 1 (Mn 6900) and ISA 23 (Mn 10,500) and their 2-phenylethylamine containing analogues ISA 4 and ISA 22 (Mn approximately 8000) were studied. All PAAs retarded the electrophoretic mobility of lambda Hind III DNA demonstrating interpolyelectrolyte complex (IPEC) formation and toroids of 80-150 nm in diameter (10:1 polymer excess) were visible using TEM. DNase II inhibition was observed. At a polymer:DNA ratio of 10:1, this was ISA 1(89.6 +/- 6.1%), ISA 4 (92.2 +/- 11.2%), ISA 22 (69.4 +/- 3.7%), and ISA 23 (58.0 +/- 10.0%). PAAs demonstrated the ability to mediate pSV beta-galactosidase transfection of HepG2 cells. At a vector:DNA mass ratio of 5:1, ISA 23 showed equivalent transfection ability compared with polyethylenimine and LipofectIN and was more effective than LipofectACE. These properties suggest that PAAs warrant further development as endosomolytic vectors.
Collapse
|
85
|
Lee N, Bertholet S, Debrabant A, Muller J, Duncan R, Nakhasi HL. Programmed cell death in the unicellular protozoan parasite Leishmania. Cell Death Differ 2002. [PMID: 11803374 DOI: 10.1038/sj/cdd/4400952] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023] Open
Abstract
In the present study we have demonstrated some features characterizing programmed cell death (PCD) in the unicellular protozoan parasite Leishmania donovani, the causative agent of visceral Leishmaniasis. We report that PCD is initiated in stationary phase cultures of promastigotes and both in actively growing cultures of axenic amastigotes and promastigotes upon treatment with anti Leishmanial drugs (Pentostam and amphotericin B). However, the two cell types respond to antileishmanial drugs differently. The features of PCD in L. donovani promastigotes are nuclear condensation, nicked DNA in the nucleus, DNA ladder formation, increase in plasma membrane permeability, decrease in the mitochondrial membrane potential (DeltaPsi m) and induction of a PhiPhiLux (PPL)-cleavage activity. PCD in both stationary phase culture and upon induction by amphotericin B resulted first in the decrease of mitochondrial membrane potential followed by simultaneous change in plasma membrane permeability and induction of PPL-cleavage activity. Of the total PPL-cleavage activity, several caspase inhibitors inhibited a significant amount (21-34%). Inhibitors of cathepsin or calpain did not inhibit PPL-cleavage activity. Taken together this study demonstrates that the characteristic features of PCD exist in unicellular protozoan Leishmania donovani. The implication of PCD on the Leishmania pathogenesis is discussed.
Collapse
|
86
|
Lee N, Bertholet S, Debrabant A, Muller J, Duncan R, Nakhasi HL. Programmed cell death in the unicellular protozoan parasite Leishmania. Cell Death Differ 2002; 9:53-64. [PMID: 11803374 DOI: 10.1038/sj.cdd.4400952] [Citation(s) in RCA: 211] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2001] [Revised: 07/23/2001] [Accepted: 08/31/2001] [Indexed: 11/08/2022] Open
Abstract
In the present study we have demonstrated some features characterizing programmed cell death (PCD) in the unicellular protozoan parasite Leishmania donovani, the causative agent of visceral Leishmaniasis. We report that PCD is initiated in stationary phase cultures of promastigotes and both in actively growing cultures of axenic amastigotes and promastigotes upon treatment with anti Leishmanial drugs (Pentostam and amphotericin B). However, the two cell types respond to antileishmanial drugs differently. The features of PCD in L. donovani promastigotes are nuclear condensation, nicked DNA in the nucleus, DNA ladder formation, increase in plasma membrane permeability, decrease in the mitochondrial membrane potential (DeltaPsi m) and induction of a PhiPhiLux (PPL)-cleavage activity. PCD in both stationary phase culture and upon induction by amphotericin B resulted first in the decrease of mitochondrial membrane potential followed by simultaneous change in plasma membrane permeability and induction of PPL-cleavage activity. Of the total PPL-cleavage activity, several caspase inhibitors inhibited a significant amount (21-34%). Inhibitors of cathepsin or calpain did not inhibit PPL-cleavage activity. Taken together this study demonstrates that the characteristic features of PCD exist in unicellular protozoan Leishmania donovani. The implication of PCD on the Leishmania pathogenesis is discussed.
Collapse
|
87
|
Pattrick NG, Richardson SC, Casolaro M, Ferruti P, Duncan R. Poly(amidoamine)-mediated intracytoplasmic delivery of ricin A-chain and gelonin. J Control Release 2001; 77:225-32. [PMID: 11733090 DOI: 10.1016/s0168-3659(01)00476-x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Poly(amidoamine)s (PAAs) are water-soluble synthetic polymers designed to be biodegradable and biocompatible. Moreover, they display membrane disruptive properties in response to a decrease in pH. This attribute confers PAAs with endosomolytic properties in vitro and in vivo. A model system was developed to quantify their ability to promote the endosomal escape of macromolecules that may be interesting as therapeutic agents. Here, two PAAs (ISA 1 and 4) were incubated with B16F10 cells in vitro together with two non-permeant toxins: either ricin A-chain (RTA) or gelonin. The relatively non-toxic PAAs ISA 1 and 4 (IC50>1.5 mg/ml) restored activity to the inherently inert toxins. The IC50 values for the ISA 1/RTA and ISA 1/gelonin combinations were 0.65+/-0.05 and 0.55+/-0.12 mg/ml, respectively. Similarly, when ISA 4 was incubated with a non-toxic combination of RTA and gelonin the IC50 value decreased to 0.57+/-0.03 and 0.43+/-0.26 mg/ml, respectively. In contrast, the neutral polymer dextran and the PAA ISA 22 were unable to mediate this effect. These observations suggest that specific PAA-toxin combinations warrant further development as novel therapeutics.
Collapse
|
88
|
Schneider R, Agol VI, Andino R, Bayard F, Cavener DR, Chappell SA, Chen JJ, Darlix JL, Dasgupta A, Donzé O, Duncan R, Elroy-Stein O, Farabaugh PJ, Filipowicz W, Gale M, Gehrke L, Goldman E, Groner Y, Harford JB, Hatzglou M, He B, Hellen CU, Hentze MW, Hershey J, Hershey P, Hohn T, Holcik M, Hunter CP, Igarashi K, Jackson R, Jagus R, Jefferson LS, Joshi B, Kaempfer R, Katze M, Kaufman RJ, Kiledjian M, Kimball SR, Kimchi A, Kirkegaard K, Koromilas AE, Krug RM, Kruys V, Lamphear BJ, Lemon S, Lloyd RE, Maquat LE, Martinez-Salas E, Mathews MB, Mauro VP, Miyamoto S, Mohr I, Morris DR, Moss EG, Nakashima N, Palmenberg A, Parkin NT, Pe'ery T, Pelletier J, Peltz S, Pestova TV, Pilipenko EV, Prats AC, Racaniello V, Read GS, Rhoads RE, Richter JD, Rivera-Pomar R, Rouault T, Sachs A, Sarnow P, Scheper GC, Schiff L, Schoenberg DR, Semler BL, Siddiqui A, Skern T, Sonenberg N, Sossin W, Standart N, Tahara SM, Thomas AA, Toulmé JJ, Wilusz J, Wimmer E, Witherell G, Wormington M. New ways of initiating translation in eukaryotes. Mol Cell Biol 2001; 21:8238-46. [PMID: 11710333 PMCID: PMC99989 DOI: 10.1128/mcb.21.23.8238-8246.2001] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
89
|
Selvapandiyan A, Duncan R, Debrabant A, Bertholet S, Sreenivas G, Negi NS, Salotra P, Nakhasi HL. Expression of a mutant form of Leishmania donovani centrin reduces the growth of the parasite. J Biol Chem 2001; 276:43253-61. [PMID: 11544261 DOI: 10.1074/jbc.m106806200] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Leishmania donovani, a protozoan parasite, causes visceral disease in humans. To identify genes that control growth, we have isolated for the first time in the order Kinetoplastida a gene encoding for centrin from L. donovani. Centrin is a calcium-binding cytoskeletal protein essential for centrosome duplication or segregation. Protein sequence similarity and immunoreactivity confirmed that Leishmania centrin is a homolog of human centrin 2. Immunofluorescence analysis localized the protein in the basal body. Calcium binding analysis revealed that its C-terminal Ca(2+) binding domain binds 16-fold more calcium than the N-terminal domain. Electrophoretic mobility shift of centrin treated with EGTA and abrogation of the shift in its mutants lacking a Ca(2+) binding site suggest that Ca(2+) binding to these regions may have a role in the protein conformation. The levels of centrin mRNA and protein were high during the exponential growth of the parasite in culture and declined to a low level in the stationary phase. Expression of N-terminal-deleted centrin in the parasite significantly reduces its growth rate, and it was found that significantly more cells are arrested in the G(2)/M stage than in control cells. These studies indicate that centrin may have a functional role in Leishmania growth.
Collapse
MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- Blotting, Northern
- Blotting, Southern
- Blotting, Western
- Calcium/metabolism
- Calcium-Binding Proteins/chemistry
- Cell Cycle
- Chromosomal Proteins, Non-Histone/chemistry
- Cloning, Molecular
- Cytoskeleton/metabolism
- Egtazic Acid/pharmacology
- Flow Cytometry
- Gene Deletion
- Immunoblotting
- Leishmania donovani/chemistry
- Leishmania donovani/genetics
- Leishmania donovani/physiology
- Microscopy, Fluorescence
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Phylogeny
- Plasmids/metabolism
- Protein Conformation
- Protein Structure, Tertiary
- RNA/metabolism
- RNA, Messenger/metabolism
- Sequence Homology, Amino Acid
- Sequence Homology, Nucleic Acid
- Time Factors
- Transfection
Collapse
|
90
|
Pedone E, Cavallaro G, Richardson SC, Duncan R, Giammona G. alpha,beta-poly(asparthylhydrazide)-glycidyltrimethylammonium chloride copolymers (PAHy-GTA): novel polymers with potential for DNA delivery. J Control Release 2001; 77:139-53. [PMID: 11689267 DOI: 10.1016/s0168-3659(01)00459-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Hydrophilic polycations form complexes when mixed with plasmids. Following functionalisation with glycidyltrimethylammonium chloride (GTA) alpha,beta-poly(asparthylhydrazide) (PAHy), a water-soluble synthetic macromolecule, becomes polycationic and potentially useful for systemic gene delivery. Initially the biocompatibility of PAHy and PAHy-GTA derivatives with different degrees of positive charge substitution were studied and it was shown that PAHy-GTA was neither haemolytic nor cytotoxicity up to 1 mg/ml. After intravenous injection (125)I-labelled PAHy-GTA derivative containing 46 mol% (PAHy-GTA(b)) of trimethylammonium groups did not accumulate in the liver (4.1+/-0.9% of the recovered dose after 1 h) but was subjected to renal excretion (45+/-21% of the recovered dose was in the kidneys after 1 h). PAHy-GTA formed complexes with DNA (gel retardation) and they protected against degradation by DNase II. Finally the ability of the PAHy-GTA(b) derivative to mediate the transfection of HepG2 cells using the marker gene beta-galactosidase was studied. The optimum plasmid/polymer mass ratio was examined in comparison to LipofectACE, Lipofectin and polyethylenimine.
Collapse
|
91
|
Hreczuk-Hirst D, Chicco D, German L, Duncan R. Dextrins as potential carriers for drug targeting: tailored rates of dextrin degradation by introduction of pendant groups. Int J Pharm 2001; 230:57-66. [PMID: 11672956 DOI: 10.1016/s0378-5173(01)00859-6] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
There is a recognised need to identify new biodegradable polymers suitable for development as targetable drug carriers. The aim of this study was to determine the rate of degradation of two dextrin fractions (Mw 15.5 and 51 KDa) by alpha-amylase and liver lysosomal enzymes (tritosomes). Also experiments were conducted to discover whether backbone modification by succinolyation (1-34 mol%) or pendant group incorporation (e.g. doxorubicin) could be used to tailor the rate of polymer degradation. Dextrin (alpha-1,4 polyglucose) is a natural polymer used clinically as a peritoneal dialysis solution and as a controlled drug delivery formulation. Size exclusion chromatography (SEC) showed that dextrin was degraded rapidly (within 20 min) by rat plasma and porcine pancreatic alpha-amylase. In contrast over 48 h no degradation was observed in the presence of tritosomes. The rate of alpha-amylase degradation of succinoylated dextrins (Mw approximately 51 KDa) was dependant on the degree of modification (dextrin >1>5>15>34 mol% succinoylation). Dextrin-doxorubicin conjugates were prepared from the 15 and 34 mol% succinoylated intermediates to have a doxorubicin loading of 8 and 12 wt.%, respectively. These doxorubicin conjugates were more stable than their parent intermediates, and SEC showed an apparently higher molecular weight. The drug conjugates did however degrade slowly over 7 days to release oligosaccharide-doxorubicin species. This fundamental study demonstrates the possibility of controlling the rate of dextrin enzymolysis by backbone modification and thus affords the potential to rationally design dextrin-drug conjugates for specific applications as targetable carriers.
Collapse
|
92
|
Duncan R, Alvarez R, Jaffe CL, Wiese M, Klutch M, Shakarian A, Dwyer D, Nakhasi HL. Early response gene expression during differentiation of cultured Leishmania donovani. Parasitol Res 2001; 87:897-906. [PMID: 11728012 DOI: 10.1007/s004360100464] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The promastigote form of the unicellular parasite, Leishmania donovani, must differentiate into the amastigote form to establish an infection in a mammalian host. Identification of genes whose expression changes during differentiation could help reveal mechanisms of Leishmania gene regulation and identify targets for controlling the diseases caused by this human pathogen. Two genomic clones were isolated, P9 that is more highly expressed in promastigotes than in axenic amastigotes and A14 that is preferentially expressed in axenic amastigotes. Analysis of the DNA sequences revealed open reading frames that would encode 55.5 kDa and 100 kDa proteins, respectively, with no homology to known proteins. The mRNA level for these genes during 24 h time courses of parasite differentiation in culture was compared to two genes known to be differentially expressed, c-lpk2 and mkk. Changes in RNA level occurred within 2 h for each gene and continued in advance of morphological changes. The expression levels of these four genes in axenic amastigotes correlated with results from animal-derived parasites.
Collapse
|
93
|
Hopewel JW, Duncan R, Wilding D, Chakrabarti K. Preclinical evaluation of the cardiotoxicity of PK2: a novel HPMA copolymer-doxorubicin-galactosamine conjugate antitumour agent. Hum Exp Toxicol 2001; 20:461-70. [PMID: 11776408 DOI: 10.1191/096032701682693017] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
PK2 is a polymeric anticancer conjugate composed of an N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer backbone and pendant doxorubicin (DOX) linked via a Gly-Phe-Leu-Gly peptide spacer. Additionally galactose residues are present to facilitate liver targeting. To justify clinical evaluation of PK2 it was necessary to determine its late cardiotoxicity compared to that of free DOX. A well standardised Sprague-Dawley rat model was used with either intravenous (i.v.) administration (4, 8 and 12 mg/kg DOX equivalent) or intraperitoneal (i.p.) administration (12, 18, 24 and 36 mg/kg DOX equivalent) of PK2. This variation in the route was due to the limited solubility of PK2 at higher doses. PK2 showed two to three times less acute toxicity (assessed by the maximum reduction in body weight in the first 2 weeks) than free DOX, and both compounds were less toxic when given i.p.. No animals given PK2 i.v. showed clinical signs of cardiotoxicity, the only toxicity seen was abnormal tooth growth (approximately 50% of the animals receiving 12 mg/kg, DOX equivalent). In contrast, several animals receiving free DOX (1-4 mg/kg) i.v. died due to cardiotoxicity in an approximately dose-related manner. All animals receiving free DOX (4 mg/kg) died by 12 weeks. Following i.p. administration of PKZ there were only two late deaths related to cardiotoxicity and these were in the 24 mg/kg DOX equivalent group. All animals receiving PK2 at the highest dose (36 mg/kg DOX equivalent) died within 4 weeks, cardiotoxicity was not the main contributing factor. In this study, PK2 displayed a approximately 5-fold reduction in cardiotoxicity relative to free DOX and this supported the progression of PK2 into early clinical investigation.
Collapse
|
94
|
Satchi R, Connors TA, Duncan R. PDEPT: polymer-directed enzyme prodrug therapy. I. HPMA copolymer-cathepsin B and PK1 as a model combination. Br J Cancer 2001; 85:1070-6. [PMID: 11592781 PMCID: PMC2375098 DOI: 10.1054/bjoc.2001.2026] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Polymer-directed enzyme prodrug therapy (PDEPT) is a novel two-step antitumour approach using a combination of a polymeric prodrug and polymer-enzyme conjugate to generate cytotoxic drug selectively at the tumour site. In this study the polymeric prodrug N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer-Gly-Phe-Leu-Gly-doxorubicin conjugate PK1 (currently under Phase II clinical evaluation) was selected as the model prodrug, and HPMA copolymer-cathepsin B as a model for the activating enzyme conjugate. Following polymer conjugation (yield of 30-35%) HPMA copolymer-cathepsin B retained approximately 20-25% enzymatic activity in vitro. To investigate pharmacokinetics in vivo,(125)I-labelled HPMA copolymer-cathepsin B was administered intravenously (i.v.) to B16F10 tumour-bearing mice. HPMA copolymer-cathespin B exhibited a longer plasma half-life (free cathepsin B t(1/2alpha)= 2.8 h; bound cathepsin B t(1/2alpha)= 3.2 h) and a 4.2-fold increase in tumour accumulation compared to the free enzyme. When PK1 (10 mg kg(-1)dox-equiv.) was injected i.v. into C57 mice bearing subcutaneously (s.c.) palpable B16F10 tumours followed after 5 h by HPMA copolymer-cathepsin B there was a rapid increase in the rate of dox release within the tumour (3.6-fold increase in the AUC compared to that seen for PK1 alone). When PK1 and the PDEPT combination were used to treat established B16F10 melanoma tumour (single dose; 10 mg kg(-1)dox-equiv.), the antitumour activity (T/C%) seen for the combination PDEPT was 168% compared to 152% seen for PK1 alone, and 144% for free dox. Also, the PDEPT combination showed activity against a COR-L23 xenograft whereas PK1 did not. PDEPT has certain advantages compared to ADEPT and GDEPT. The relatively short plasma residence time of the polymeric prodrug allows subsequent administration of polymer-enzyme without fear of prodrug activation in the circulation and polymer-enzyme conjugates have reduced immunogenicity. This study proves the concept of PDEPT and further optimisation is warranted.
Collapse
|
95
|
Duncan R. Not doing nothing. AUSTRALIAN NURSING JOURNAL (JULY 1993) 2001; 9:46-7. [PMID: 11908124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
|
96
|
Searle F, Gac-Breton S, Keane R, Dimitrijevic S, Brocchini S, Sausville EA, Duncan R. N-(2-hydroxypropyl)methacrylamide copolymer-6-(3-aminopropyl)-ellipticine conjugates. Synthesis, in vitro, and preliminary in vivo evaluation. Bioconjug Chem 2001; 12:711-8. [PMID: 11562189 DOI: 10.1021/bc0001544] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ellipticine derivatives have potential as anticancer drugs. Their clinical use has been limited, however, by poor solubility and host toxicity. As N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-anticancer conjugates are showing promise in early clinical trials, a series of novel HPMA copolymer conjugates have been prepared containing the 6-(3-aminopropyl)-ellipticine derivative (APE, NSC176328). Drug was linked to the polymer via GFLG or GG peptide side chains. To optimize biological behavior, HPMA copolymer-GFLG-APE conjugates with different drug loading (total APE: 2.3-7% w/w; free APE: <0.1% w/w) were synthesized. Conjugation of APE to HPMA copolymers considerably increased its aqueous solubility (>10-fold). HPMA copolymer-GG-APE did not liberate drug in the presence of isolated lysosomal enzymes (tritosomes), but HPMA copolymer-GFLG-APE released APE to a maximum of 60% after 5 h. The rate of drug release was influenced by drug loading; lower loading led to greater release. Whereas free APE (35 microg/mL) caused significant hemolysis (50% after 1 h), HPMA copolymer-APE conjugates were not hemolytic up to 300 microg/mL (APE-equiv). As would be expected from its cellular pharmacokinetics, HPMA copolymer-GFLG-APE was >75 times less cytotoxic than free drug (IC(50) approximately 0.4 microg/mL) against B16F10 melanoma in vitro. However, in vivo when tested in mice bearing s.c. B16F10 melanoma, HPMA copolymer-GFLG-APE (1-10 mg/kg single dose, APE-equiv) given i.p. was somewhat more active (highest T/C value of 143%) than free APE (1 mg/kg) (T/C =127%). HPMA copolymer-APE conjugates warrant further evaluation as potential anticancer agents.
Collapse
|
97
|
Espie CA, Watkins J, Duncan R, Espie A, Sterrick M, Brodie MJ, McGarvey C, Curtice L. Development and validation of the Glasgow Epilepsy Outcome Scale (GEOS): a new instrument for measuring concerns about epilepsy in people with mental retardation. Epilepsia 2001; 42:1043-51. [PMID: 11554892 DOI: 10.1046/j.1528-1157.2001.0420081043.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To develop a measure for use with adults with epilepsy and mental retardation, capable of assessing both clinical and care concerns and of quantifying treatment outcomes. METHODS Extensive validational and other psychometric evaluation was undertaken, comprising initial scale development work with 48 carers and 46 health practitioners, followed by formal field testing on a sample of 186 patients, using 384 respondents (160 clinicians, 141 staff, 83 family). Recognised qualitative methods were applied to identify central themes, and psychometric procedures generated data on validity, reliability, and component structure. RESULTS A total of 1,007 items of concern was generated, which was reduced systematically to a representative set of 90 items. The GEOS-90 comprises four subscales: concerns about "seizures," "treatment," "caring," and "social impact," each explaining approximately 70% of variance. Subscales and factor scales had strong internal consistency (alpha > or = 0.82). Stepwise linear regression was applied to derive a short-form version with similar structure. Thirty-five items were retained (GEOS-35; alpha > or = 0.89). Both scales discriminated moderately on clinical variables (number of seizure types, mono- vs. polytherapy, seizure frequency; all values of p < 0.05) and demonstrated concurrent validity with interview ratings from the ELDQOL (p < 0.05). CONCLUSIONS The GEOS scales appear valid and reliable for use with clinical populations of people with mental retardation.
Collapse
|
98
|
Abstract
Brain perfusion changes during seizures were first observed in the 1930s. Single Photon Emission Computed Tomography (SPECT) was developed in the 1970s, and tracers suitable for the imaging of regional cerebral perfusion (rCP) became available in the 1980s. The method was first used to study rCP in the interictal phase, and this showed areas of low perfusion in a proportion of cases, mainly in patients with temporal lobe epilepsies. However, the trapping paradigm of tracers such as hexamethyl propyleneamine oxime (HMPAO) provided a practicable method of studying changes in rCP during seizures, and a literature was established in the late 1980s and early 1990s showing a typical sequence of changes during and after seizures of mesial temporal lobe origin; the ictal phase was associated with large increases in perfusion throughout the temporal lobe, with first the lateral, then the mesial temporal lobe becoming hypoperfused in the postictal phase. Activation and inhibition of other structures, such as the basal ganglia and frontal cortex, were also seen. Studies of seizures originating elsewhere in the brain have shown a variety of patterns of change, according to the structures involved. These changes have been used practically to aid the process of localisation of the epileptogenic zone so that epilepsy surgery can be planned. Some neuroreceptors (e.g. benzodiazepine receptors) can be studied using SPECT, and have shown localised abnormalities. SPECT has also been used to study brain function during the intracarotid amytal test. SPECT images of all kinds can be analysed using numerical techniques such as statistical parametric mapping, and such techniques promise to improve the yield of information from ictal studies.
Collapse
|
99
|
Duncan R, Gac-Breton S, Keane R, Musila R, Sat YN, Satchi R, Searle F. Polymer-drug conjugates, PDEPT and PELT: basic principles for design and transfer from the laboratory to clinic. J Control Release 2001; 74:135-46. [PMID: 11489490 DOI: 10.1016/s0168-3659(01)00328-5] [Citation(s) in RCA: 159] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
There are now at least seven polymer-drug conjugates that have entered phase I/II clinical trial as anticancer agents. These include N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-doxorubicin (PK1, FCE28068), HPMA copolymer-paclitaxel (PNU 166945), HPMA copolymer-camptothecin, PEG-camptothecin, polyglutamic acid-paclitaxel, an HPMA copolymer-platinate (AP5280) and also an HPMA copolymer-doxorubicin conjugate bearing additionally galactosamine (PK2, FCE28069). The galactosamine is used as a means to target the conjugate to liver for the treatment of primary and secondary liver cancer. Promising early clinical results with lysosomotropic conjugates has stimulated significant interest in this field. Ongoing research is developing (1) conjugates containing drugs that could otherwise not progress due to poor solubility or uncontrollable toxicity; (2) conjugates of agents directed against novel targets; and (3) two-step combinations such as polymer-directed enzyme prodrug therapy (PDEPT) and polymer-enzyme liposome therapy (PELT) that can cause explosive liberation of drug from either polymeric prodrugs or liposomes within the tumour interstitium. Moreover, bioresponsive polymer-based constructs able to promote endosomal escape and thus intracytoplasmic delivery of macromolecular drugs (peptides, proteins and oligonucleotides) are also under study.
Collapse
|
100
|
Patrick M, Duncan R, Coombs KM. Generation and genetic characterization of avian reovirus temperature-sensitive mutants. Virology 2001; 284:113-22. [PMID: 11352672 DOI: 10.1006/viro.2001.0915] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
There currently is little known about the genetic and biological functions of avian reovirus (ARV), an atypical member of the family Reoviridae and the prototype of all nonenveloped viruses that induce syncytia formation. In this study, we created ARV temperature-sensitive (ts) mutants by chemical mutagenesis of ARV strain 138. We developed a novel efficiency of lysis (EOL) screening technique and used it and the classical efficiency of plating (EOP) assay to identify 17 ARV ts mutants. Pairwise mixed infections of these mutants and evaluation of recombinant progeny ts status led to their organization into seven recombination groups. This indicates that these new groups of mutants represent the majority of the ARV genome. To phenotypically characterize the ts mutants, progeny double-stranded RNA (dsRNA) produced at permissive and nonpermissive temperature was measured. Some mutants were capable of dsRNA synthesis at the restrictive temperature (RNA(+)), which indicates the effects of their ts lesions occur after RNA replication. Most mutants were RNA(-), which suggests their mutations affect stages in viral replication that precede progeny genome synthesis.
Collapse
|