Hospitalisation and resource utilisation in patients with schizophrenia following initiation of risperidone long-acting therapy in the Veterans Affairs Healthcare System

OBJECTIVE

To examine hospitalisation rates and resource utilisation following initiation of risperidone long-acting therapy (RLAT) among US veterans with schizophrenia.

METHODS

Encounter data were analysed from the Ohio Veterans Affairs (VA) Healthcare System. Adult patients (schizophrenia or schizoaffective disorder) with ≥1 medical or hospital visits with a diagnosis code of 295.xx, continuous enrolment from January 2003 through January 2006, and ≥4 injections of RLAT were selected. Analyses compared psychiatric-related resource utilisation pre- and post-exposure to RLAT; each patient served as his/her own control. The pre-exposure and post-exposure periods defined were equal in duration (e.g., a 6-month post-exposure period was matched with a 6-month pre-exposure period). Descriptive and comparative analyses (paired t tests, McNemar's test) were performed.

RESULTS

Patients (n=106) were 51.9 years old (+/-10.2), male (93%), white (73%) and received on average 14 RLAT doses (+/-9.7; range, 4-47 injections) over 309 days (+/-196; range, 42-737 days). Most experienced a psychiatric-related hospitalisation prior to initiation; less than half experienced hospitalisation after initiation (75% vs. 42%; p<0.001). Relative to pre-initiation, fewer psychiatric-related hospitalisations (mean [SD] change, -0.8 [2.0]; p<0.001), shorter length of stay (-25 [63.6] days; p<0.001), fewer inpatient days/month (-3.1 [7.2] days) and one (2.8) additional outpatient visit/month (p<0.001) occurred post-initiation.

LIMITATIONS

The absence of a control group in this pre-/post comparison may have resulted in exposure to a regression to the mean effect. Also, this study evaluated only one cohort of patients in a VA healthcare setting.

CONCLUSIONS

VA patients with schizophrenia and schizoaffective disorder treated with RLAT experienced fewer hospitalisations and psychiatric-related inpatient days following RLAT initiation. Further studies utilising a control group and in non-VA populations are warranted.

Phage display screening of epithelial cell monolayers treated with EGTA: identification of peptide FDFWITP that modulates tight junction activity

Phage display was used to screen for peptides that modulate the activity of epithelial cell tight junctions. Panning with a phage library that displays random 7-mers was performed using monolayers of human bronchial epithelial cells (16HBE14o(-)) treated with a calcium chelator, ethylene glycol-bis(2-aminoethylether)- N, N, N', N'-tetraacetic acid (EGTA), to increase accessibility to the junctional complex/paracellular space, followed by subtractive panning. A novel peptide, FDFWITP, identified as a potential tight junction modulator, was synthesized in linear and cyclic forms with lysine residues added to improve solubility. The cyclic form of the peptide reduced transepithelial electrical resistance (TER) in a concentration-dependent manner (80% reduction at 100 microM and 95% reduction at 500 microM) and was reversible within 2 h; the linear form only affected TER at the highest concentration. Interestingly, the constrained peptide did not increase permeation of the model small molecule, fluorescein. The highly selective activity of FDFWITP supports the hypothesis that ions and small molecules may be transported paracellularly across tight junctions by separate pathways.

The Trp cage motif as a scaffold for the display of a randomized peptide library on bacteriophage T7

Phage libraries displaying linear or disulfide-constrained peptides often yield weak binders, upon screening against a target, and must be optimized to improve affinity. The disadvantages of libraries based on larger complex proteins, such as single chain antibodies, have stimulated interest in the development of smaller nonimmunoglobulin protein scaffolds. A promising candidate is the Trp cage motif, a 20-residue C-terminal sequence of exendin-4. Amino acid substitution within the Trp cage resulted in a 20-mer peptide recognized as an ultrafast cooperative folding miniprotein, with ideal characteristics for the discovery of small structured nonimmunoglobulin motifs having a stable tertiary structure. Although we were unable to display the Trp cage on M13 phage, successful display was achieved using the lytic T7 phage. Interestingly, mutations were observed at a frequency dependent on display valency. A Trp cage library designed with randomized amino acids at seven solvent-exposed positions was developed from 1.6 x 10(9) primary clones in T7Select10-3b. DNA sequencing of 109 library clones revealed 38% mutants and 16% truncations by TAG codons at randomized positions. Amino acid frequencies were largely within expected bounds and DIVAA analysis revealed that the library had an average diversity of 0.67. Utility of the library was demonstrated by identification of HPQ containing Trp cage miniproteins, which bound streptavidin, and AAADPYAQWLQSMGPHSGRPPPR, which bound to human bronchial epithelial cells. A high complexity library based on the Trp cage miniprotein has demonstrated potential for identifying novel cell and protein binding peptides that could be used for the delivery of therapeutic molecules or as target-specific therapeutic agents.

Effect of intravenous contrast on treatment planning system dose calculations in the lung?

Intravenous contrast-enhanced computed tomography is utilised in radiotherapy lung treatment planning to improve the delineation of the tumour volume and nodal areas. In the resultant CT images, the electron density is increased within the vascular structures of the lung and the overall density in the lung volume may also be increased. As yet, it is unclear whether the change in density affects the accuracy of dose calculations based on this CT data. Two investigations were undertaken. Firstly, contrast-enhancement was simulated using an anthropomorphic phantom. In the second investigation, bulk density corrections were performed in an existing patient dataset. In both investigations, treatment plans were generated using both pre- and post-contrast datasets. The numbers of monitor units calculated in each of the plans were compared, as were the resulting isodose curves, dose volume histograms and physical mean lung doses. The numbers of monitor units calculated from the contrast- and non contrast-enhanced datasets agreed within 2%. The isodose curves and dose volume histograms showed very minor differences in size and shape. With the introduction of contrast agent, the physical mean lung doses calculated remained below the limit recommended for an acceptable plan. These results indicate that the introduction of contrast agent has a minimal dosimetric impact upon lung cancer treatment plans.

Can the Use of HIV-1 Derived Gene Transfer Vectors for Clinical Application be Justified?

Vectors derived from human immunodeficiency virus type 1 (HIV-1) are an attractive option for many gene therapy applications as they can transduce non-cycling cell populations, and can integrate their genome into the host cell chromosome. The rationale underlying the design of most retroviral vector systems is to segregate the viral cis sequences, which are required for transfer of the viral genome, from the trans sequences that encode viral proteins. This allows the efficient production of replication incompetent virus and has been successfully applied to the generation of HIV-1 vectors. Nonetheless, the possibility that recombination events in the vector production system can generate replication-competent virus, combined with the pathogenic nature of HIV-1, raises major bio-safety issues. Numerous HIV-1 vectors have now been reported, with each generation significantly improved in ways designed to reduce the risk of replication-competent virus being produced. However, progress in vector design needs to be complemented by the development of methods for the quantitation of the probability of replication competent virus being produced. Assaying individual events in the multi-step pathway that can lead to the production of replication-competent virus, rather than relying on the detection of replication-competent virus per se, will be important for quality control purposes. This review will specifically examine the approaches to HIV-1 vector design that have been postulated as increasing bio-safety, possible methods for evaluating bio-safety and whether these approaches are likely to be sufficient to overcome resistance to the use of HIV-1 for clinical application. In addition, we discuss the possible justifications for developing vectors from lentiviruses other than HIV-1.

Mass spectrometry in the study of lysosomal storage disorders

Lysosomal storage disorders represent a group of over 45 distinct genetic diseases, each one resulting from a deficiency of a particular lysosomal protein or, in a few cases, from non-lysosomal proteins that are involved in lysosomal biogenesis. A common biochemical feature of this group of disorders is the accumulation within lysosomes of undegraded or partially degraded substrates that are normally degraded within, and transported out of the lysosome. The particular substrates stored and the site(s) of storage vary with disease type and enzyme/protein deficiency. The nature of the substrate can be used to group the disorders into broad categories including the mucopolysaccharidoses, lipidoses, glycogenoses and oligosaccharidoses. These categories show many clinical similarities within groups as well as significant similarities between groups. For most lysosomal storage disorders the relationship between the stored substrates (type, amount and location) and the disease pathology is not well understood. The use of mass spectrometry and in particular tandem mass spectrometry provides a powerful tool for the investigation of stored substrates in this group of disorders. In this review we will describe the use of mass spectrometry for the analysis of stored substrates. We will discuss progress in the field, limitations of current methods, and summarise issues relating to the diagnosis and treatment of some of the more prevalent lysosomal storage disorders.

Rational development of a HIV-1 gene therapy vector

BACKGROUND

HIV-1 provides an attractive option as the basis for gene transfer vectors due to its ability to stably transduce non-cycling cell populations. In order to fully utilise the promise of HIV-1 as a vector it is important that the effects of viral cis sequence elements on vector function are carefully delineated.

METHODS

In this study we have systematically evaluated the effect of various cis elements from the HIV-1 YU-2 genome that have been implicated as either affecting vector performance, or HIV-1 replication, on the efficiency of vector production (titre and infectivity). As a measure of the relative safety of vectors their propensity to inadvertently transfer the gagpol gene to transduced cells was assessed.

RESULTS

Sequences that were found to increase vector titre were from the 5' end of the gag gene, from the 5' and 3' ends of the env gene, from immediately upstream of the polypurine tract, and the central polypurine tract. The substitution of the HIV-1 RRE with heterologous RNA transport elements, or the deletion of the RRE, resulted in greatly reduced vector titres. RNA analysis suggested that the role of the Rev/RRE system extends beyond simply acting as an RNA nuclear export signal. The relative safety of different vector designs was compared and an optimal construct selected.

CONCLUSIONS

Based on our results we have constructed a vector that is both more efficient, and has better safety characteristics, than the widely used pHR' HIV-1 vector construct.

On the confirmation of an effect of magnetic fields on the interictal firing rate of epileptic patients

The effect of magnetic fields on interictal firing rates was investigated in three epileptic patients with depth electrode implantation in the hippocampus for pre-surgical evaluation. The protocol consisted of 10 min test periods, during which magnetic fields were cycled for 1 min on and 1 min off, and intervening 5 min rest periods. Only one patient revealed a 95% significant increase in the 10 s after the fields were switched on compared with the background estimate from the 10s before the fields were applied. This patient was also the only patient to show significant increases in firing rates during field-on compared with field-off periods, and during magnetic field test periods compared with intervening rest periods. This patient had a right hippocampal seizure onset. All patients showed increased firing rates during the 10 min periods of magnetic field testing compared to the 5 min rest periods between tests. This result was significant for the group at the 99% level. Two patients with right temporal lobe onset showed greater activity in the right hippocampus than the left. All patients exhibited a progressive increase in firing rates in rest periods between tests.

Helper plasmids for production of HIV-1-derived vectors

Vectors derived from human immunodeficiency virus type 1 (HIV-1) appear an attractive option for many gene therapy applications. This is due to their ability to transduce noncycling cell populations and to integrate their genome into the host cell chromosome, resulting in the stable genetic modification of the transduced cell. These properties have permitted the direct in vivo transduction of several tissues, including the central nervous system, retina, and liver. However, the pathogenic nature of HIV-1 has raised considerable concerns about the safety of such vector systems. To help address these concerns, we have expressed each of the primary transcriptional units encoding trans functions relevant for vector production in individual plasmid constructs. The gag-pol gene sequence was codon-optimized for expression in mammalian cells resulting in high level Rev/Rev-response element (RRE)-independent expression. Codon optimization of gag-pol also reduces sequence homology with vectors containing gag gene sequences, which results in reduced transfer of biologically active gag-pol sequences to transduced cells. Furthermore, the vif reading frame overlapping the 3' end of the pol coding sequence is destroyed by codon optimization. We have also shown that the Gag and Gag-Pol polyproteins can be efficiently expressed from separate transcriptional units. This has enabled the removal of a cis-acting viral element, the gag-pol translational frameshift sequence, from the vector/packaging system and prevents detectable transfer of biologically active sequences equivalent to the gag-pol gene to transduced cells.

Prefrontal cortical sulcal widening associated with poor treatment response to clozapine

Increased sulcal widening in the prefrontal cortex of patients with schizophrenia may be associated with a poor treatment response to clozapine. To further evaluate this, we examined data from patients treated with clozapine in our center. Patients with the greatest degree of improvement (n=26) and those with no improvement (n=10) were compared. Computerized tomography (CT) scans were rated blindly on a visual scale of prefrontal sulcal widening. Patients with the greatest degree of functional improvement had significantly less prefrontal sulcal widening than those whose symptoms remained unchanged. There was no relationship between clozapine response and general sulcal widening. These data support the link between the superior therapeutic efficacy of clozapine and the integrity of the prefrontal cortex.

Changes in paroxysmal brainwave patterns of epileptics by weak-field magnetic stimulation

In order to assess the effects of weak-field magnetic stimulation on brain electrical activity in epileptics, three patients suffering from mesial temporal lobe epilepsy (MTLE) were exposed to DC magnetic fields of 0.9 and 1.8 millitesla (mT). The EEG activity was recorded simultaneously from intracranial electrodes inserted through the foramen ovale (FO) and scalp electrodes. Significant enhancement of interictal epileptiform activity was observed in two patients, while in one patient, magnetic stimulation resulted in the cessation of interictal spike/wave trains.

Recombinant canine alpha-l-fucosidase: expression, purification, and characterization

Canine fucosidosis has proven to be an excellent large animal model both for the equivalent human disorder and, in more general terms, for the central nervous system pathology found in many of the lysosomal storage disorders. Most importantly studies in this animal model were among the first to convincingly show that bone marrow transplantation could successfully modify the course of clinical central nervous system disease and to define some of the important parameters for successful treatment. In order to evaluate other, more generally applicable routes to treatment of central nervous system disease in the lysosomal storage disorders we have expressed recombinant canine alpha-l-fucosidase (rcFUC) in Chinese hamster ovary and Madin-Darby canine kidney cells to levels of between 2 and 13 mg/liter of culture medium and purified the enzyme to apparent homogeneity by affinity chromatography on fucosylamine-linked agarose. rcFUC is composed of subunits of M(r) 50 kDa and the native enzyme is a homotrimer of M(r) 156 kDa. Kinetic properties of rcFUC were similar to those of FUC isolated from both human and dog liver. rcFUC was shown to be effective in correcting the storage phenotype of human fucosidosis cells after endocytosis via the mannose-6-phosphate-receptor-mediated pathway. It was also shown to degrade fucosylated storage products isolated from affected dog brain. The availability of large amounts of rcFUC will allow us to explore ways of extending the proven efficacy of enzyme replacement therapy to the treatment of central nervous system pathology using the fucosidosis dog as a model system.

Malignant catatonia-induced respiratory failure with response to ECT

A 47-year-old acutely psychotic schizophrenic man was diagnosed with malignant catatonia. Because of a history of neuroleptic malignant syndrome (NMS), traditional neuroleptics were avoided, and the patient had been treated with reserpine for a period of 10 years. Symptomatically, severe agitation alternated with severe retardation. The syndrome progressed, despite early termination of any neuroleptic medications, to marked catatonic rigidity and dehydration. Worsening was associated with transfer to a medical intensive care unit, intubation, and subsequently a tracheostomy. Dantrolene and bromocriptine were unhelpful. Lorazepam produced muscular relaxation and resulting decreases in creatine phosphokinase levels but elicited no other improvement. Eleven bilateral electroconvulsive treatments, however, resolved the respiratory impairment and catatonia and improved the psychosis. This report highlights the efficacy of ECT in lethal catatonia despite respiratory impairment and tracheostomy.

Social inequalities and health in rural Chiapas, Mexico: agricultural economy, nutrition, and child health in La Fraylesca region

The objective of this study was to investigate the association between farmers' socioeconomic conditions and their children's health in La Fraylesca, Chiapas. Data were collected using a cross-sectional survey of 1046 households (5546 individuals) sampled from locations in two counties situated in the study area. The survey included anthropometric measurements, a 24-hour dietary recall, stool tests, and childhood mortality data. Children of private farmers and "wealthy peasants" displayed better nutritional status, higher quality diet, lower prevalence of intestinal parasites, and a lower risk of dying than those whose parents were communal farmers, from ejidos, or "poor peasants". The results suggest that using volume of maize production as a classification method proved more valuable than land tenure to identify agricultural groups with different health status. It appears that the main determinants of health differentials are structural inequities in resource distribution. Thus, the impact of medical interventions on inequalities will be limited unless they are accompanied by redistribution of resources.

Nefazodone therapy in patients with treatment-resistant or treatment-intolerant depression and high psychiatric comorbidity

Given the potentially severe functional impairment, morbidity, and high costs associated with refractory depression, it is important to explore all treatment options that may benefit patients with this disorder. This is a retrospective, uncontrolled analysis of our experience with nefazodone therapy in treatment-resistant and treatment-intolerant depression. Potential candidates for nefazodone therapy were referred by their treating psychiatrist. Documentation of failure to respond to previous antidepressant therapy, a diagnosis of clinical depression according to criteria in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, and completion of a Beck Depression Inventory (BDI) were required before initiation of nefazodone. A follow-up BDI was obtained after > or =4 weeks of nefazodone therapy. A Clinical Global Inventory (CGI) score was obtained retrospectively based on documentation of target symptoms in the clinical record of the last clinic visit. The study group consisted of 20 patients with treatment-resistant or treatment-intolerant major depression who received nefazodone therapy. The mean (+/- SD) age of the group was 48.1+/-9.4 years. The mean number of previously failed antidepressant trials was 1.9+/-0.6. Psychiatric comorbidity in this group was substantial, with posttraumatic stress disorder (PTSD) found in 11 (55%) patients, substance abuse in 3 (15%) patients, and personality disorder found in 2 (10%) patients. After treatment with nefazodone, 11 of 20 patients (55%) were rated on the CGI as much or very much improved. In addition, 9 patients (45%) had >20% improvement on BDI, 3 patients (15%) had 10% to 20% improvement, and 6 patients (30%) had <10% change. Two patients (10%) discontinued nefazodone therapy due to adverse effects. Analysis of our experience with nefazodone therapy in a population with treatment-resistant depression and a high degree of psychiatric comorbidity suggests that approximately 50% of patients may have substantial response to treatment, with a smaller proportion having a more modest clinical response. While receiving nefazodone therapy, most patients continued to take concurrently prescribed psychotropic medications, primarily anxiolytics or other antidepressants. Of interest was the positive drug response among a subgroup of individuals with depression and chronic, severe PTSD. Larger, controlled studies are needed to determine whether these preliminary observations are confirmed.

Receptor mediated binding of two glycosylation forms of N-acetylgalactosamine-4-sulphatase

The lysosomal storage disorders are a group of inherited metabolic diseases each characterised by a relative or absolute deficiency of one or more of the lysosomal proteins involved in the hydrolysis of glycoconjugates or in the transport of the resulting product. Enzyme replacement therapies are under consideration for a number of these disorders and are based on the in vitro observation that cells from affected patients can be corrected by addition of exogenous enzyme. In this study, two glycosylation variants of the lysosomal enzyme N-acetylgalactosamine-4-sulphatase (4S) (the deficiency of which causes Mucopolysaccharidosis (MPS) type VI, (Maroteaux-Lamy syndrome) were made by expression of 4S cDNA in both wild type chinese hamster ovary (CHO-K1), and Lec1 (N-acetylglucosaminyltransferase I deficient CHO-K1) cells. Differences in the glycosylation pattern of the two enzyme forms were demonstrated with endoglycosidase H and N-glycosidase F digestions. The receptor mediated binding of these two forms of 4S to two cell types, human skin fibroblasts and rat alveolar macrophages, was then analysed. We have shown that both enzyme forms bind to the mannose-6-phosphate receptor on human skin fibroblasts with equal affinity demonstrating that the degree of phosphorylation of mannose residues in the two forms is similar. However, using rat alveolar macrophages, we found that the binding/uptake of the two enzymes differs considerably. These results show that differences in glycosylation of lysosomal enzymes can be an important factor in altering enzyme uptake by different cell types. Thus, producing carbohydrate modification variants in this way may be useful for altering the distribution of exogenous enzyme in vivo.

The Repertoire of Social Behaviours of Agile Wallabies, Macropus agilis

The repertoire of social behaviours of the Agile Wallaby, Macropus agilis, was compiled from observations of free-ranging and captive animals in the vicinity of Darwin, Northern Territory. Behaviours were divided into general, maternal, agonistic and sexual contexts. A larger repertoire of behaviours was recorded from captive wallabies but most of these behaviours, except subtle acts like Flehmen and sexual vocalisations, were also seen in free-ranging individuals. The social behaviours of M. agilis are similar to those of other species in the subgenus Prionotemnus. Macropus agilis performed tail-lashing (in sexual, agonistic and general contexts) and males did not use sustained tail support during fights, features which distinguish Prionotemnus from the other subgenera of Macropus. Macropus agilis gave a foot-thump flight signal but also tapped their feet when aware of a potential threat. More complex sexual and agonistic acts which occur in Whiptail Wallabies (Macropus parryi), Euros (Macropus robustus) and Grey Kangaroos (Macropus giganteus) were not observed in M. agilis.

Canine fucosidosis: a model for retroviral gene transfer into haematopoietic stem cells

Severe progressive fatal neurological degeneration occurs in fucosidosis, a storage disease. Bone marrow transplantation into affected dogs has shown that haematopoietic stem cells can provide enzyme producing daughter cells to the central nervous system, altering disease course. This makes canine fucosidosis an ideal large animal model for gene therapy. Fucosidosis affected allogeneic or autologous canine marrow was transduced ex vivo by cocultivation, then transplanted into fucosidosis affected dogs conditioned with total lymphoid irradiation. The vectors were Moloney murine leukaemia virus based. Transduction efficiency was increased with multiple cytokines in short term marrow culture. Despite high levels of transduction, proviral sequence was detected 2 months post transplant in only one dog. Early or total graft failure occurred in all transplants. We believe lack of engraftment could be caused by differentiation or change of repopulating ability of marrow cells occurring with multiple cytokine mixes in culture media.

Neurotrophic immunophilin ligands stimulate structural and functional recovery in neurodegenerative animal models

Although immunosuppressant immunophilin ligands promote neurite outgrowth in vitro, their neurotrophic activities are clearly independent of their immunosuppressive activity. In the present report, a novel nonimmunosuppressive immunophilin ligand, GPI-1046 (3-(3-pyridyl)-1-propyl (2S)-1-(3,3-dimethyl-1,2-dioxopentyl)-2-pyrrolidinecarboxylate+ ++) is described. In vitro, GPI-1046 bound to FK506 binding protein-12 and elicited neurite outgrowth from sensory neuronal cultures with picomolar potency with maximal effects comparable to nerve growth factor. In vivo, GPI-1046 stimulated the regeneration of lesioned sciatic nerve axons and myelin levels. In the central nervous system, GPI-1046 promoted protection and/or sprouting of serotonin-containing nerve fibers in somatosensory cortex following parachloroamphetamine treatment. GPI-1046 also induced regenerative sprouting from spared nigrostriatal dopaminergic neurons following 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine toxicity in mice or 6-hydroxydopamine (6-OHDA) toxicity in rats. The rotational abnormality in 6-OHDA treated rats was alleviated by GPI-1046. These neurotrophic actions in multiple models suggest therapeutic utility for GPI-1046 in neurodegenerative diseases.

Isolation and characterisation of a recombinant, precursor form of lysosomal acid alpha-glucosidase

Glycogenosis type II (GSD II, Pompe disease) is an autosomal recessive lysosomal storage disease that results from a deficiency of acid alpha-glucosidase (GAA). Patients with this disorder are unable to break down lysosomal glycogen, which consequently accumulates in the lysosome. To evaluate enzyme replacement therapy for GSD II patients, we have expressed human GAA cDNA in Chinese hamster ovary-K1 cells utilising a vector that places the cDNA under the transcriptional control of the human polypeptide chain elongation factor 1 alpha gene promoter. A clonal cell line that secreted precursor recombinant GAA at approximately 18 mg.l-1.day-1 was identified. The precursor recombinant GAA was purified to homogeneity, had a molecular mass of 110 kDa as measured by SDS/PAGE, and was shown to have pH optima and kinetic parameters similar to those of GAA purified from human tissues. The partial N-terminal amino acid sequence of recombinant GAA conformed to that derived from the nucleotide sequence of the cloned cDNA. The recombinant enzyme was taken up by cultured fibroblasts and skeletal muscle cells from GSD II patients, and was shown to correct the storage phenotype. Endocytosed GAA was localised to the lysosome and showed evidence of intracellular processing to a more mature form. Activity levels increased up to twice the normal value and uptake was prevented if cells were cultured in the presence of mannose 6-phosphate.

Expression, purification and characterization of recombinant human N-acetylgalactosamine-6-sulphatase

Full-length cDNA sequences encoding human N-acetylgalactosamine-6-sulphatase were stably expressed in Chinese hamster ovary cells under the transcriptional control of the human polypeptide chain elongation factor 1 alpha gene promoter. A clonal cell line overexpressing recombinant N-acetylgalactosamine-6-sulphatase to a level of approx. 3 mg/l of culture medium was isolated. The secreted precursor enzyme was purified to homogeneity by a two-column procedure with an overall yield of 53% of the activity. The physical and catalytic parameters of the recombinant enzyme were similar to those of the mature form isolated from liver. On SDS/PAGE and gel filtration, recombinant N-acetylgalactosamine-6-sulphatase had a native molecular mass of 58-60 kDa. Recombinant N-acetylgalactosamine-6-sulphatase was endocytosed by mucopolysaccharidosis IVA fibroblasts via the mannose-6-phosphate receptor-mediated pathway and was efficiently localized to lysosomes.

Spontaneous sustained ventricular tachycardia in the Electrophysiologic Study Versus Electrocardiographic Monitoring (ESVEM) Trial

OBJECTIVES

We compared the QRS waveforms of the initial and subsequent complexes of spontaneous sustained monomorphic ventricular tachycardia and the rhythm induced at electrophysiologic study to test the theory that premature ventricular complexes "trigger" spontaneous ventricular tachycardia and that a stable substrate exists such that the spontaneous arrhythmia can be reproduced at electrophysiologic study.

BACKGROUND

Failure rates have been high in several recent studies in which prevention of ventricular tachyarrhythmias was guided by suppression of premature ventricular complexes or induced ventricular tachycardias.

METHODS

Digital waveform analysis was used to distinguish events of ventricular tachycardia initiated by configurationally distinct, possibly triggering, complexes (type 1) from events in which the initial QRS waveforms were identical to subsequent complexes, suggesting no requirement for premature ventricular beats (type 2).

RESULTS

Of 1,102 episodes of spontaneous ventricular tachycardia, 73 (6.6%) were type 1; 1,012 were type 2 (91.8%); and 17 (1.5%) were uncertain. Of 59 patients only 14 (24%) had only type 1 episodes (group 1), whereas 37 patients (63%) had predominantly type 2 events (group 2) (p < 0.0001). Sustained ventricular tachycardia was inducible in all group 1 patients, and in most (57%) the induced rhythm was similar to the spontaneous rhythm. Ventricular tachycardia could not be induced in 7 patients from group 2 (19%), and in 18 patients (49%) the induced and spontaneous rhythms were dissimilar. Recurrence of arrhythmia rates differed according to the guidance method in group 2.

CONCLUSIONS

Discrepancies between observed and predicted modes of initiation of ventricular tachycardia and between spontaneous and induced rhythms could result in inappropriate guidance and subsequent failure of antiarrhythmic treatment.

Cyclohexylamine inhibits the adhesion of lymphocytic cells to human syncytiotrophoblast

We have previously shown that lymphocytic cells adhere to cultured syncytiotrophoblast and that this may be important in the lymphocyte-mediated infection of trophoblast with the human immunodeficiency virus (HIV). During the course of studies aimed at investigating the role of cell surface carbohydrates in adhesion, it was discovered that a contaminant of commercial fucose-1-phosphate, dicyclohexylamine, inhibited MOLT-trophoblast adhesion. Dicyclohexylamine and the related compounds, cyclohexylamine and hexylamine, inhibited adhesion in a dose-responsive manner with half-maximal inhibition seen at about 4 mM. While the pressor effects of cyclohexylamine, the principal metabolite of cyclamate, are well known, this is the first report of an effect of this and related compounds on cell adhesion activity. The inhibitory effect was reversible and, at concentrations less than 25 mM, did not result in loss of cell viability. Several possible mechanisms of action of cyclohexylamine were examined in an attempt to explain the effect on adhesion. No evidence was found to suggest that the effects of cyclohexylamine were due to inhibition of polyamine synthesis, increase in intracellular Ca2+ concentration or to a lysosomotropic effect. The concentrations of cyclohexylamine used are within the range of plasma concentrations attainable in humans, raising the possibility that the in vitro effects described here may also occur in vivo. The results also suggest that caution should be used in the interpretation of results obtained from experiments where cell adhesion is blocked using exogenous monosaccharides that are in the form of dicyclohexylammonium salts. Appropriate controls must be included or, if possible, sodium, potassium or barium salts should be chosen.

On the sensitivity of the human brain to magnetic fields: evocation of epileptiform activity

Evocation of epileptiform activity by DC magnetic fields of between 0.9 and 1.8 millitesla (mT) has been demonstrated in 6 epileptic patients undergoing presurgical evaluation. The activity was monitored by electroencephalography (EEG) recording from both electrodes attached to the scalp as well as from intracranial electrodes inserted via the foramen ovale. Epileptiform activity evoked by the magnetic field application was distinguished from background levels by comparing the number of epileptiform discharges in the 10-s intervals before and after field applications. In nearly all cases, a delay of up to several seconds was observed between the application of the magnetic field and the onset of epileptiform firing. Removal of the field also appeared to cause firing in some instances, but this has not yet been investigated systematically. In all 6 patients, subsequent seizures confirmed that the epileptiform activity monitored during the experiments was originating from the primary epileptogenic zones of the patients.

Estimating ECG distributions from small numbers of leads

The utility of body surface potential mapping to improve interpretation of electrocardiographic information lies in the presentation of thoracic surface distributions to characterize underlying electrophysiology less ambiguously than that afforded by conventional electrocardiography. Localized cardiac disease or abnormal electrophysiology presents itself electrocardiographically on the body surface in a manner in which pattern plays an important role for identifying or characterizing these abnormalities. Thus, in myocardial infarction, transient myocardial ischemia, Wolff-Parkinson-White syndrome, or ventricular ectopy, observation of electrocardiographic potential patterns, their extrema, and their magnitudes permits localization and quantization of the abnormal activity. Conventional electrocardiography assesses pattern information incompletely and does not use information of distribution extrema locations or magnitudes. Thus, increases or decreases in the magnitudes of electrocardiographic features (ST-segment potential displacement, amplitude, or morphology of Q, R, S, or T waves) associated with changes in cardiac sources (ischemia, infarction, conduction abnormalities, etc.) as measured from fixed leads have a high likelihood of being misinterpreted if the distribution itself is changing. In this study, the authors demonstrate the utility of estimating distributions from small numbers of optimally selected leads, including conventional leads, to reduce uncertainty in the interpretation of electrocardiographic information. This issue is highly relevant when thresholds are used to detect significance of potential levels (exercise testing, detection of myocardial infarction, and continuous monitoring to assess ST-segment changes). Significance of this work lies in improved detection and characterization of abnormal electrophysiology using conventional or enhanced leadsets and methods to estimate thoracic potential distributions.

Magnetic material in the human hippocampus

Magnetic analyses of hippocampal material from deceased normal and epileptic subjects, and from the surgically removed epileptogenic zone of a living patient have been carried out. All had magnetic characteristics similar to those reported for other parts of the brain [6]. These characteristics along with low temperature analysis indicate that the magnetic material is present in a wide range of grain sizes. The low temperature analysis also revealed the presence of magnetite through manifestation of its low temperature transition. The wide range of grain sizes is similar to magnetite produced extracellularly by the GS-15 strain of bacteria and unlike that found in magnetotactic bacteria MV-1, which has a restricted grain size range. Optical microscopy of slices revealed rare 5-10 micron clusters of finer opaque particles, which were demonstrated with Magnetic Force Microscopy to be magnetic. One of these was shown with EDAX to contain AI, Ca, Fe, and K, with approximate weight percentages of 55, 19, 19, and 5, respectively.

Criteria for local myocardial electrical activation: effects of electrogram characteristics

Detection of local electrical myocardial activation by means of extracellular recordings is often difficult in the presence of polyphasic electrograms. The purpose of this investigation was to compare the ability of several variables to distinguish unipolar deflections due to local activation from those due to nonlocal activity. A model of polyphasic deflections based on atrial recordings during reentrant tachycardia was used to facilitate distinction of local and distant activity by methods independent of the test variables. The performance of variables were assessed by comparing areas under receiver operating characteristic curves. Optimal thresholds of test variables were identified by maximizing statistics which corrected for the pretest probability of local activation. We found that the greatest negative first derivative of the unipolar potential discriminated between local and distant ventricular signals, but performed less well than the ratio of the first derivative to the potential for distinguishing between local atrial signals and distant ventricular signals. A linear combination of the potential and the ratio of the first derivative and the potential performed well for all groups of signals studied. We conclude that optimal criteria for detecting local activation depends on the characteristics of the population of signals and that a statistical approach can be used to identify optimal criteria for a given population.

A review of hospitalized patients with bacterial gastroenteritis

The distribution and clinical management of thirty-two hospitalized patients with salmonella and campylobacter infections were reviewed and the impact of these infections on hospital resources was assessed. Eighteen patients with salmonella infection had an age and sex distribution comparable with the community cases. In contrast, 10 out of 14 (71.4%) patients with campylobacter infection were under 20 years of age though the peak incidence of the infection in the community occurred in the 21-65 years age group (67%). There was no male predominance. The median duration of stay in hospital was 6 days for patients with salmonella infection and 3 days for those with campylobacter infection. Physicians were inconsistent in the treatment of campylobacter infection. Overall the financial impact of managing patients with salmonella and campylobacter infection was considerable (1384 pounds and 779 pounds respectively per patient). A limitation on unnecessarily prolonged hospital stays and the establishment of clear guidelines for the clinical management of these infections are necessary.

Determination of local myocardial electrical activation for activation sequence mapping. A statistical approach

Electrical activation sequence mapping requires accurate identification of local activation, but because extracellular recordings do not exclusively reflect local events, complex electrograms may be difficult to interpret. In such cases, the assignment of local activation is subject to error that could affect interpretation of the resulting activation maps. The purpose of this investigation was to develop an approach that would provide quantitative indexes of error in the determination of local activation. An electrode array with 64 closely spaced unipolar electrodes was used to record from the left ventricular surface during open heart surgery. Electrograms with multiple deflections were recorded from four patients with scarred myocardium; two other patients with normal myocardial function served as controls. Each of 784 deflections was scored on the basis of three features: evidence for propagation, the configuration of the bipolar signal, and the effect of changing from the chest to an average reference. Local activation was considered probable if evidence for all three features was present and improbable if none of the three features was present. Deflections that were ambiguous with respect to this standard were excluded. Of over 30 test variables analyzed, the three with the greatest power to discriminate signals due to local activation from those due to distant activity were 1) a linear combination of the extracellular potential plus the ratio of the second derivative and the extracellular potential, 2) the second derivative, and 3) the minimum (greatest negative) first derivative. For each of these variables, the threshold value providing the greatest performance was identified by the maximum quality of efficiency, an index of agreement. This statistical approach provides an objective basis for determining local activation and provides a quantitative assessment of error that could enhance interpretation of electrical activation sequence maps.

Correlates of breast-feeding in a low-income population of whites, blacks, and southeast Asians

Infant feeding was examined in 492 children in a population-based survey conducted in a low-income, urban county of St Paul, Minn. Of 41 Southeast Asian infants who were foreign born, 93% (38) had been breast-fed compared with 10% (12) of Southeast Asian infants born in the United States (n = 116). Among non-Southeast Asian infants, 73% (173) of whites (n = 237), 63% (27) of blacks (n = 43) and 65% (36) of other ethnic groups (n = 55) had been breast-fed. Among the non-Southeast Asian infants, the initiation of breast-feeding was associated with higher parental education and with being married. Ethnic group, level of poverty, and participation in the Supplemental Food Program for Women, Infants, and Children during pregnancy did not appear to influence the initiation of breast-feeding. The findings indicate a higher incidence of breast-feeding than in previous surveys of low-income black and white women; however, this may reflect the higher educational level of the non-Southeast Asian study population. In contrast, the sharp decline in the incidence of breast-feeding among Southeast Asian infants who were born in the United States compared with those who were foreign born indicates the need for public health approaches to strengthen traditional breast-feeding practices.