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Biomedical subjects

C Binnie

Publications and source records attributed to C Binnie.

At least 19 recordsLinked to original sources
PubMed2001

Proof of principle trials: EEG surrogate endpoints.

Pivotal studies in man require prolonged administration to demonstrate efficacy for most seizure types. Earlier evidence of human efficacy can be of value for decision making, and EEG surrogate endpoints can be of value in this respect. Studies of spontaneous EEG discharges under standard recording conditions can demonstrate meaningful acute EEG effects of antiepileptic drugs (AEDs). These require a rapidly effective formulation of the product, preferably intravenous. The EEG recording conditions are standardised and the subject is required to perform a task to maintain a constant level of vigilance. The outcome measure of efficacy is spike count per minute or, if the discharges are more protracted (as generalised no spike and wave), the percentage of recording time occupied by discharges. Sub-acute experiments are conducted under less rigorously standardised conditions, but over longer periods, using ambulatory monitoring or telemetry to record the EEG. The photoparoxysmal responses (PPRs) of photosensitive subjects, evoked using a standardised stimulation protocol, are subject to less variability than spontaneous epileptiform activity. The PPR is elicited over a range of flash rates that can be used as a measure of sensitivity, and an effective treatment will reduce the range or abolish the PPR. Reduction in photosensitivity is demonstrable after a single dose of various AEDs, at clinically relevant plasma concentrations, even using drugs that are not generally effective for long-term treatment of photosensitive epilepsy. Evoked potential and nerve conduction studies and electronystagmography can be used to assess possible neurotoxicity, and quantitative EEG analysis can be employed to assess sedative effects.

Animals↗
PubMed2001

Multiple subpial transection in Landau-Kleffner syndrome.

We have considered multiple subpial transection (MST) as a treatment option for Landau-Kleffner syndrome (LKS) for the past 6 years. The effect of this technique on language and cognitive ability, behaviour, seizures, and EEG abnormalities is analysed here. Five children (4 males, 1 female; aged 5.5 to 10 years) underwent MST with sufficiently detailed pre- and postoperative data for analysis. Behaviour and seizure frequency improved dramatically after surgery in all children. Improvement in language also occurred in all children, although none improved to an age-appropriate level. All five had electrical status epilepticus in sleep (ESES) before surgery, which was eliminated by the procedure. One child has had an extension of his MST due to the recurrence of ESES and accompanying clinical deterioration with good effect. An attempt is made to set the effect of MST against the natural history of the condition. MST is an important treatment modality in LKS, although the timing of this intervention and its effect on final language outcome remains to be defined.

Cerebral Cortex↗
PubMed2000

The epilepsy tutorial.

Within the European Neurological Network (ENN) project an interactive multimedia tutorial covering the medical field of epilepsy has been created. The first priorities of that project to educate health care professionals, e.g. General Practitioners (GP), throughout the European community as how to best diagnose and treat patients (e.g. reduction of frequent consultations, avoiding of excessive and unnecessary medication and useless laboratory tests) and to inform patients and carers are reached by producing a distributable CD-ROM. Later frequent updates of the content of the installed tutorial will take place by a telematic network contacting the multimedia database of the ENN-project. Using the toolbook author-system with integrated sound, images, animation and videos the data collected from about 10 experts are arranged as an electronic book, with multiple-linked pages and an object oriented program design, based for instance on customisable navigation buttons, special text arrangement, graphics, and staging areas for content and interaction display. The multimedia tutorial about epilepsy contains case reports, specific multiple choice questions with scoring, video clips etc. and several possibilities for access such as help-pages available all times, index, search machine for phrases, bookmark settings and roadmaps for graphical orientation. Detailed text is prepared including physiology and pathophysiology, differential diagnosis, investigations, therapeutics, epilepsy in children, advice for patients and carers, and is supported by a glossary, special definitions and proposals for classification of the different kinds of epilepsy. The tutorial runs with Windows 3.1, 95 and NT and contains 1300 pages text with 382 Fig.s, 14 videos, 70 sound files, 196 definitions and 8 roadmaps. The epilepsy tutorial has been distributed in March/May 1998 to more than 100 general physicians in Germany, Portugal and France.

Adolescent↗
PubMed1997

The Maudsley Family Study, II: Endogenous event-related potentials in familial schizophrenia.

Auditory event-related potentials (ERPs) were obtained from 33 schizophrenics, from 16 families multiply affected with schizophrenia, 57 of their non-schizophrenic first-degree relatives and 32 unrelated healthy controls. Transmission of schizophrenia in these families appeared unilinear with one parent only transmitting the disorder. Consequently, we were able to identify 10 presumed obligate carriers and study eight of them. Schizophrenic patients showed latency prolongation and amplitude reduction of the N100, N200 and P300 waves compared to controls. Their relatives showed similar abnormalities compared to controls. There was a trend for bimodal distribution of the P300 latency in the relatives, with 20 (35%) of them falling outside two standard deviations of the mean of the controls. These included six of the eight obligate carriers. Our results suggest that ERP abnormalities may serve as markers of genetic vulnerability in schizophrenia and may be useful in genetic linkage studies.

Adult↗
PubMed1997

Expression and characterization of soluble human erythropoietin receptor made in Streptomyces lividans 66.

A gene encoding the extracellular domain of the human erythropoietin receptor (EPO-R) was constructed using oligonucleotides, with a view to maintaining preferred codon usage for the Streptomycetes. The gene was subcloned into a multicopy Streptomyces-Escherichia coli shuttle vector, pCAN46 (derived from pIJ680), containing a strong constitutive promoter from the S. fradiae aph gene, a signal peptide coding region derived from the protease B gene of S. griseus, and a transcription terminator sequence also derived from the S. fradiae aph gene. Extracellular expression of authentic EPO-R by S. lividans was demonstrated using SDS-PAGE and Western blot analysis, followed by direct amino terminal sequencing of the purified product. Specific binding of S. lividans-expressed EPO-R to recombinant human glycosylated EPO was demonstrated using BIAcore (surface plasmon resonance) analysis and native gel shift assays.

Base Sequence↗
PubMed1997

Heterologous biopharmaceutical protein expression in Streptomyces.

The commercial production of human proteins in recombinant microorganisms for therapeutic use is well established. Systems have been developed to exploit the natural ability of certain bacteria to secrete properly folded, bioactive proteins into the extracellular medium. The streptomycetes are a relatively well-characterized group of nonpathogenic filamentous bacteria that have the capacity to secrete large amounts of protein. In particular, Streptomyces lividans has the ability to secrete human proteins at a commercially viable level, thanks to relatively well-established plasmid-based expression system, a high-biomass fermentation process and a low level of endogenous protease activity.

Bacterial Proteins↗
PubMed1996

Cloning and analysis of a gene from Streptomyces lividans 66 encoding a novel secreted protease exhibiting homology to subtilisin BPN'.

Amino-terminal degradation has been observed for many of the secreted heterologous proteins produced by S. lividans 66. We, therefore, set out to characterize the relevant proteinases and their genes. A tripeptide chromogenic substrate was used to identify a gene that was shown to encode a secreted protein which removed tripeptides from the amino terminus of extracellular proteins (tripeptidyl aminopeptidase, Tap; Butler et al. 1995). This activity was removed by a homologous gene deletion replacement and the ability of the S. lividans strain to remove N-terminal tripeptides was greatly reduced, but still significant. When the tap-deleted strain was used as a host for the rescreening of a S. lividans 66 genomic DNA library, a number of other genes encoding proteases with aminopeptidase activities were discovered. One clone (P5-4) produced a 45-kDa secreted protein (Ssp), which showed activity against Ala-Pro-Ala-beta-naphthylamide (APA-beta NH-Nap) substrate. Further analysis of the cloned DNA showed an open-reading frame encoding a protein larger than 45 kDa. Direct Edman degradation of the secreted protein confirmed that it was encoded within the cloned DNA and probably processed from a larger precursor. Protein sequence analysis revealed a striking homology to subtilisin BPN' in three regions around the active-site residues suggesting that the protein is a serine protease. As expected, the protease activity was inhibited by phenylmethylsulphonyl fluoride. Mutant strains with most of the ssp gene deleted exhibited reduced activity against APA-beta NH-Nap substrate compared to their non-deleted parental strains.

Amino Acid Sequence↗
PubMed1996

Isolation and characterization of a gene encoding a chymotrypsin-like serine protease from Streptomyces lividans 66.

A gene encoding a Streptomyces lividans homologue of the chymotrypsin-like serine protease (SAM-P20) of Streptomyces albogriseolus was isolated using the Streptomyces griseus prtB gene as a hybridization probe. Nucleotide sequence analysis of a representative clone uncovered the possible presence of a sequence of 900 nucleotides encoding 300 amino acids, including a putative "prepro" region of 115 amino acids. Alignment of the predicted amino acid sequence of this putative gene with other members of the family of Streptomyces extracellular chymotrypsin-like proteases indicated a high degree of homology in all cases, especially with the SAM-P20 protease. This gene product has been identified as the second member of a potentially larger family of SAL (SAM-P20-like) proteases in S. lividans 66.

Amino Acid Sequence↗
PubMed1995

Cloning and characterization of a gene encoding a secreted tripeptidyl aminopeptidase from Streptomyces lividans 66.

The gene encoding a tripeptidyl aminopeptidase (Tap) from Streptomyces lividans was cloned by using a simple agar plate activity assay. Overexpression of the cloned gene results in the production of a secreted protein which has an apparent subunit molecular weight of 55,000 and is responsible for the major amino-terminal degradative activity in culture broths of S. lividans strains. A DNA sequence analysis revealed a potential protein-encoding region of the size expected to encode the observed protein, which contained a sequence that exhibited significant homology around a putative active site serine residue observed for lipases, esterases, and acyl transferases. Preceding the amino terminus of the secreted protein was a predicted signal peptide of 36 amino acids followed by a tripeptide, which could be autocatalytically removed from a secreted Tap precursor. The transcriptional start site for the gene was mapped by primer extension. Mutant strains of S. lividans lacking detectable Tap activity were able to grow and sporulate normally. Cross-species hybridization experiments showed that DNA homologs of the tap gene are present in most of the Streptomyces strains tested.

Amino Acid Sequence↗
PubMed1995

Isolation and characterization of two genes encoding proteases associated with the mycelium of Streptomyces lividans 66.

A strain of Streptomyces lividans 66 deleted for a major tripeptidyl aminopeptidase (Tap) was used as a host to screen an S. lividans genomic library for clones overexpressing activity against the chromogenic substrate Ala-Pro-Ala-beta-naphthylamide. In addition to reisolation of the tap gene, clones representing another locus, slpD, were uncovered. slpD was analyzed by deletion subcloning to localize its functional sequence. Nucleotide sequence determination revealed an open reading frame encoding a 55-kDa protein exhibiting significant amino acid sequence homology to Tap, particularly around the putative active-site serine residue. No secreted protein was observed for strains harboring the slpD clone, but inspection of the predicted protein sequence revealed a putative lipoprotein signal peptide (signal peptidase II type), suggesting a mycelial location for the SlpD proteinase. In an attempt to isolate an endoprotease known to be active against some heterologous proteins, a second clone was isolated by using a longer substrate (t-butyloxycarbonyl [Boc]-APARSPA-beta-naphthylamide) containing a chemical blocking group at the amino terminus to prevent aminopeptidase cleavage. This locus, slpE, appeared to also encode a 55-kDa mycelium-associated (lipoprotein) proteinase, whose predicted protein sequences showed significant amino acid homology to Tap and SlpD, particularly around the putative active-site serine residues. Chromosomal integration and deletion analysis in both the wild-type and Tap-deficient backgrounds appeared to indicate that SlpD was essential for viability and SlpE was required for growth on minimal media.

Amino Acid Sequence↗
PubMed1994

The aminopeptidase N-encoding pepN gene of Streptomyces lividans 66.

The gene (pepN) encoding an aminopeptidase N (PepN) has been cloned from Streptomyces lividans. This was done using either leucine-beta-naphthylamide or arginine-beta-naphthylamide in a liquid overlayer on colonies growing on agar medium to screen for overproduction of the ability to hydrolyse the substrates. The nucleotide sequence of pepN was determined and shown to encode a 95-kDa protein, which displayed significant homology to PepN proteins from other organisms. Analysis of the overproduced proteinase confirmed that this protein was located intracellularly as a monomeric active species. PepN is a metallo-exopeptidase cleaving next to Leu, Arg and Lys in peptide-bond-containing substrates.

Amino Acid Sequence↗
PubMed1993

Seasonal affective disorder: response to light as measured by electroencephalogram, melatonin suppression, and cerebral blood flow.

This study was designed to test the hypothesis that patients with SAD have significantly different physiological responses to light than healthy age- and sex-matched controls. We studied retinal contrast sensitivity, visual evoked EEG responses, and melatonin suppression by, and cerebral blood flow response to, full-spectrum artificial daylight. There was no significant difference between 10 patients and 11 controls in retinal contrast sensitivity, or amplitude or latency of N2, P2, P100 or P300 on EEG. We compared melatonin suppression in 12 SAD patients and 12 controls. During exposure to 500 lux and 1500 lux artificial daylight both the SAD patients and controls had a significant melatonin percentage suppression; however, the percentage suppression did not differ significantly between the SAD patients and the controls. In addition, we carried out a small pilot study into the effect of light on cerebral blood flow in four SAD patients and four controls. Before exposure to 1500 lux artificial daylight there was no significant difference between patients and controls in global, regional or cerebral hemispheric blood flow. After light exposure the SAD patients and controls had a significantly different percentage change in cerebral blood flow. We suggest that patients with SAD do not have significantly physiological responses to light than controls, except perhaps in cerebral blood flow. Furthermore, mechanisms other than supersensitivity of melatonin suppression must explain both the pathophysiology of the disorder and its response to treatment with light.

Bipolar Disorder↗
PubMed1992

A new technique for fractal analysis applied to human, intracerebrally recorded, ictal electroencephalographic signals.

Application of a new method of fractal analysis to human, intracerebrally recorded, ictal electroencephalographic (EEG) signals is reported. 'Frameshift-Richardson' (FR) analysis involves estimation of fractal dimension (1 < FD < 2) of consecutive, overlapping 10-s epochs of digitised EEG data; it is suggested that this technique offers significant operational advantages over use of algorithms for FD estimation requiring preliminary reconstruction of EEG data in phase space. FR analysis was found to reduce substantially the volume of EEG data, without loss of diagnostically important information concerning onset, propagation and evolution of ictal EEG discharges. Arrhythmic EEG events were correlated with relatively increased FD; rhythmic EEG events with relatively decreased FD. It is proposed that development of this method may lead to: (i) enhanced definition and localisation of initial ictal changes in the EEG presumed due to multi-unit activity; and (ii) synoptic visualisation of long periods of EEG data.

Algorithms↗