Covalent coupling of concanavalin A to a Carbopol 934P and 941P carrier in glucose-sensitive gels for delivery of insulin

A novel glucose-sensitive gel formulation, containing concanavalin A and specific polysaccharides, was stabilised via covalent coupling to two structurally different carbomers. The bonding was done to minimise leaching of gel components thereby preventing toxicity and preserving the working mechanism of the gel. Increased gel stability was introduced by covalently bonding amine groups present on the lysine residues of concanavalin A to carboxylic moieties on Carbopol 934P NF and 941P NF using carbodiimide chemistry. The introduction of dextran then produced a glucose-sensitive formulation that transformed from gel to sol in the presence of free glucose. Rheological examination of glucose-sensitive gels stabilised in this way and containing varying concentrations of glucose was conducted with a cone and plate viscometer used in continual rotation mode. A decrease in viscosity over the chosen glucose concentration range was exhibited by both carbomer-stabilised formulations. The subsequent testing of such formulations in in-vitro diffusion experiments revealed that the leaching of concanavalin A from the covalently coupled gels is restricted significantly with respect to non-coupled formulations. In addition, insulin delivery in response to glucose in the physiologically relevant glucose concentration range has been demonstrated using the carbomer-stabilised gels at 37 degrees C. The performance of this self-regulating drug delivery system has been improved in terms of increased gel stability with reduced component leaching.

A covalently stabilised glucose responsive gel formulation with a Carbopol carrier

A novel glucose-responsive gel formulation was stabilised via covalent coupling to a carbomer resin. The gel formed between the plant lectin, concanavalin A and specific polysaccharides was stabilised to minimise leaching of gel components into the surroundings. This was required to prevent toxicity and to preserve the working mechanism of the formulation. Increased gel stability was introduced by covalently bonding amine groups present on the lysine residues of concanavalin A to carboxylic moieties on Carbopol 974P NF using carbodiimide chemistry. The introduction of dextran then produced a glucose-responsive formulation that transformed from gel to sol in the presence of free glucose. The rheological properties and in vitro component and insulin release of the carbomer-stabilised gel were evaluated. A decrease in viscosity over a chosen glucose concentration range was exhibited by the carbomer-based gel. The testing of such a formulation in in vitro diffusion experiments revealed that the leaching of concanavalin A from the covalently coupled gels was restricted significantly with respect to a non-coupled gel. Insulin delivery in response to glucose in the physiologically relevant glucose concentration range was demonstrated using the carbomer-stabilised gel at 37 degrees C. The performance of this novel self-regulating drug delivery system has been improved in terms of increased gel stability with reduced component leaching.

Visual categorization during childhood: an ERP study

Categorization is a basic means of organizing the world around us and offers a simple way to process the mass of stimuli one perceives every day. The ability to categorize appears early in infancy, and has important ramifications for the acquisition of other cognitive capacities, but little is known of its development during childhood. We studied 48 children (7-15 years of age) and 14 adults using an animal/nonanimal visual categorization task while event-related potentials (ERPs) were recorded. Three components were measured: P1, N2, and P3. Behaviorally, the children performed the task very similarly to adults, although the children took longer to make categorization responses. Decreases in latencies (N2, P3) and amplitudes (P1, N2, P3) with age indicated that categorization processes continue to develop through childhood. P1 latency did not differ between the age groups. N2 latency, which is associated with stimulus categorization, reached adult levels at 9 years and P3 latency at 11 years of age. Age-related amplitude decreases started after the maturational changes in latencies were finished.

Islet cryopreservation using intracellular preservation solutions

Cryopreservation of islets adds great flexibility to clinical islet transplant programs. Methods of islet cryopreservation have traditionally utilized permeating cryoprotectants contained within isotonic solutions without specifically addressing issues of ionic balances, buffering capacity, or oxygen free radicals that occur during hypothermic stresses. These factors may become significant issues during low-temperature storage and during the freezing and thawing process. Since its development in the early 1980s, the University of Wisconsin (UW) organ preservation solution has become the standard vascular flush and preservation solution. Recently, Hypothermosol preservation solution (HTS) was developed as a hypothermic blood substitute. The unique characteristics and composition of these preservation solutions may be important when developing solutions specific for the cryopreservation of cells and tissues. It was the aim of this study to evaluate these two hypothermic preservation solutions as the media used in cryopreservation of islets. Groups of canine islets [5000 islet equivalents (IE)/group] were cryopreserved using the standard protocol of stepwise addition of dimethyl sulfoxide (DMSO) to 2 M, controlled nucleation, slow cooling (0.25 degrees C/min), and rapid thawing (200 degrees C/min). The cryopreservation solutions were made with 1) UW solution, 2) HTS solution, or 3) Medium 199 solution with 10% fetal calf serum (FCS). Additional control groups included islets cryopreserved using 4) HTS, 5) UW solution, and 6) Medium 199 alone, without DMSO. Recovery of islets immediately following thawing was equivalent between the groups with the exception of the islets cryopreserved without DMSO (groups 4-6, p < 0.05). After 48 h of postcryopreservation tissue culture, islet recovery was highest in the groups frozen with UW and HTS (mean +/- SEM) (79.8 +/- 1.9% and 82.5 +/- 1.5%, p < 0.05 vs. group 3, 69.1 +/- 3.3%, p < 0.05, ANOVA). Less than 15% of the islets were recovered when they were cryopreserved without the cryoprotectant DMSO (groups 4-6). Functional viability was assessed by measuring the glucose-stimulated insulin secretion during static incubation after 48-h culture. The stimulation indexes were 4.6 +/- 1.0, 4.2 +/- 0.8, 3.6 +/- 1.2, 0.6 +/- 0.5, and 0.4 +/- 0.2 for islets in groups 1-5, respectively. This study demonstrates that postcryopreservation survival can be improved using intracellular-based preservation solutions, including UW or HTS, in conjunction with DMSO.

Development of a sandwich ELISA and comparison with PCR for the detection of F11 and F165 fimbriated Escherichia coli isolates from septicaemic disease in farm animals

The P fimbriae F11 and F165 that have been demonstrated on Escherichia coli septicaemic strains in poultry and calves, respectively, possess a nearly identical major subunit that demonstrates a serological cross-reaction. A polyclonal antibody-based sandwich ELISA (sELISA) that was specific for both F11 and F165 fimbriated strains was compared with a PCR method to detect F11/F165 fimbriated strains, in a collection of E. coli strains isolated from diseased animals. Of 298 isolates tested, 36 were positive by PCR of which only 14 were sELISA positive. There were no sELISA positive but PCR negative results. The 36 PCR positive isolates comprised 11 avian strains of which 10 were sELISA positive, 20 bovine strains of which 4 were sELISA positive and 3 ovine strains, 1 porcine strain and 1 equine strain all of which were sELISA negative. The F11/F165 incidence of 10.7% in 103 poultry and 18.3% in 109 bovine isolates demonstrates a moderate level of these factors in E. coli septicaemic cases in Northern Ireland.

Magnetoencephalographic evidence of early processing of direction of gaze in humans

Despite the crucial importance of direction of gaze in social interactions, it is only recently that there has been interest in human brain responses to gaze direction. Using full-head magnetoencephalography, we investigated the correlates of direction of gaze in full faces and in eyes-only stimuli, measuring the early face-responsive component between 145 and 225 ms. Faces with eyes forward or averted had larger responses than faces with eyes up or closed. For eyes-only stimuli the shortest latencies were seen for eyes averted and the smallest amplitudes were seen for eyes closed. The data were explained by two dipoles in inferior-temporal regions, which showed greater activation for upright faces than face parts or inverted faces, as well as some sensitivity to direction of gaze in this very early stage of processing.

Severe reactions to filarial chemotherapy and release of Wolbachia endosymbionts into blood

Wolbachia bacteria seem to have evolved as essential endosymbionts of their filarial nematode hosts. Studies in mice have suggested that these bacteria are associated with systemic inflammatory reactions to filarial chemotherapy. We took blood samples from 15 Indonesian patients before and after treatment with diethylcarbamazine for Brugia malayi infection, and recorded the severity of any post-treatment inflammatory reactions. Blood from all three patients with severe adverse reactions and from one of six with moderate reactions was positive for Wolbachia DNA 4-48 h after diethylcarbamazine treatment. We suggest that these severe inflammatory reactions are associated with the release of endosymbionts into the blood after treatment for filariasis.

Natural and experimental nematode infections in red deer (Cervus elaphus elaphus) and the potential for antemortem serodiagnosis of the tissue worm Elaphostrongylus cervi

Red deer (Cervus elaphus elaphus) were exposed to a variety of nematodes, either naturally on pasture (n = 12) or experimentally under controlled conditions (n = 30). Experimental exposures included a combination of one or more of Elaphostrongylus cervi, Dictyocaulus sp., and Muellerius capillaris. The prepatent period of E. cervi infections was 92–133 days post exposure (dpe) in 12 deer each given 20–42 infective larvae (L3) and maintained under controlled conditions. Adult E. cervi were recovered from all 12 animals at necropsy. The prepatent period of Dictyocaulus sp. was 23–37 dpe in 10 deer each given 100 L3 and maintained under controlled conditions. Adult Dictyocaulus sp. were recovered from seven animals at necropsy. No animal exposed to 42–54 M. capillaris L3 developed patent infections, nor were adult worms recovered at necropsy. There was no evidence of neurologic signs in any deer at any time during the experiment. An enzyme-linked immunosorbent assay (ELISA) using somatic protein extracts of adult E. cervi or those from the closely related nematode Parelaphostrongylus tenuis was evaluated. Although the ELISA was sensitive, it lacked specificity with heterologous infections. However, the close phylogenetic relationship of E. cervi to P. tenuis, and our ELISA results, suggest that molecules from P. tenuis may represent a viable alternative source for use in the future development of a reliable antemortem serodiagnostic assay for E. cervi.

A new approach to the treatment of filariasis

The symbiosis of filarial nematodes and intracellular Wolbachia bacteria has recently been exploited as a target for antibiotic therapy of filariasis. Antibiotic treatment of filarial nematodes results in sterility and inhibits larval development and adult worm viability. In the first trial on human onchocerciasis depletion of bacteria following treatment with doxycycline resulted in a complete and long-term block of embryogenesis. Bacteria are unable to repopulate nematode tissues up to 18 months after depletion, suggesting these effects may be permanent. Following ivermectin treatment, individuals given antibiotic therapy showed sustained reductions in skin microfilariae, with the majority of people remaining microfilarial negative 12-18 months after treatment. Since Wolbachia also contribute to the inflammatory pathogenesis of filarial disease, antibiotic therapy could, in addition to effects on worm fertility or viability, prevent the onset or development of filarial pathology.

Sensitivity and specificity of WAIS-III/WMS-III demographically corrected factor scores in neuropsychological assessment

This study explored the neurodiagnostic utility of 6 factor scores identified by recent exploratory and confirmatory factor analyses of the WAIS-III and WMS-III: Verbal Comprehension, Perceptual Organization, Processing Speed, Working Memory, Auditory Memory and Visual Memory. Factor scores were corrected for age. education, sex and ethnicity to minimize their influences on diagnostic accuracy. Cut-offs at 1, 1.5 and 2 standard deviations (SDs) below the standardization sample mean were applied to data from the overlapping test normative samples (N = 1073) and 6 clinical samples described in the WAIS-III/WMS-III Technical Manual (N = 126). The analyses suggest that a I SD cut-off yields the most balanced levels of sensitivity and specificity; more strict (1.5 or 2 SD) cut-offs generally result in trading modest gains in specificity for larger losses in sensitivity. Finally, using combinations of WAIS-III/WMS-III factors together as test batteries, we explored the sensitivity and specificity implications of varying diagnostic decision rules (e.g.,1 vs. 2 impaired factors = "impairment"). For most of the disorders considered here, even a small (e.g., 3 factor) WAIS-III/WMS-III battery provides quite good overall diagnostic accuracy.

Freehand three-dimensional Doppler demonstration of monochorionic vascular anastomoses in vivo: a preliminary report

OBJECTIVES

To demonstrate the three-dimensional vascular anatomy of monochorionic placental anastomoses in vivo, both arterioarterial and arteriovenous.

DESIGN

Two-dimensional placental mapping techniques were used to locate arterioarterial and arteriovenous anastomoses. A freehand sweep was performed across the anastomotic site, and multiple images were stored to disk, at 17 Hz. These were then segmented to show only color information (vascular flow) using purpose-designed software (CQ analysis) and the files reconstructed into a three-dimensional volume, for multidirectional viewing and movie generation.

RESULTS

Both arterioarterial and arteriovenous anastomoses could be visualized in detail. Reconstruction of a dual volume of gray-scale and segmented color images allowed recreation of the vascular anatomy within the placental substance, as well as retention of the original directional flow information.

CONCLUSIONS

Detailed anastomotic anatomy can be demonstrated three dimensionally in vivo. Given the increasing evidence implicating various anastomotic configurations in pathological intertwin transfusion, this technique may prove useful in the antenatal assessment and treatment of monochorionic twin pregnancies.

The effect of jararhagin, a metalloproteinase from Bothrops jararaca venom, on pro-inflammatory cytokines released by murine peritoneal adherent cells

The release of pro-inflammatory cytokines (IL-1beta, IL-6 and TNF-alpha) from murine peritoneal adherent cells (MPAC) was studied after exposure to jararhagin, a metalloproteinase/disintegrin isolated from Bothrops jararaca venom. MPACs were treated with LPS (lipopolysaccharide), jararhagin, or EDTA-inactivated jararhagin for up to 24h. Following incubation, the culture supernatant was assayed by ELISA for the presence of cytokines, while the cells were analysed for viability and cytokine mRNA expression. The cells exposed to native jararhagin released TNF-alpha and IL-1beta after 4 and 24h respectively. When MPACs were exposed to Jararhagin treated with EDTA, TNF-alpha and IL-1beta production was sustained throughout the culture period and IL-6 production was observed. TNF-alpha, IL-6 and IL-1beta mRNA were detected 4h after stimulation with either native or EDTA-treated jararhagin. Addition of jararhagin to LPS stimulated cells resulted in a dramatic decrease in the release of IL-6 and TNF-alpha. RT-PCR showed that this inhibition does not occur at the transcriptional level and further experiments showed that jararhagin degraded soluble cytokines by proteolytic activity. This study suggests that jararhagin induces TNF-alpha, IL-1beta and IL-6 expression, which may be rapidly degraded by its proteolytic activity.

Development of three-dimensional power Doppler ultrasound imaging of fetoplacental vasculature

To develop an off-line system for three-dimensional (3-D) ultrasound (US) reconstruction of fetoplacental vasculature using colour segmentation and reconstruction software and to determine sources of error in fully freehand ultrasound image acquisition. US images were acquired freehand with the Acuson Sequoia (5C 2-MHz transducer) using power Doppler. After digital transfer to a personal computer, CQ Analysis software (Kinetic Imaging Ltd, Liverpool, UK) was used to segment the colour information from these images, and the resulting 8-bit grey-scale images were used for 3-D rendering using commercial software (VoxBlast, Vaytek Inc., Fairfield, IA, USA). 2-D scanning, software and freehand acquisition accuracy were assessed using a linear test rig and distance and volume phantoms (Dansk Phantom Service Ltd); 2-D scanning accuracy was within 1.3%, and software reconstruction accuracy within 1% for x and y planes and up to 3% for the z plane. Fully freehand acquisition was associated with a 12% to 18% mean percentage error in distance measurement in the plane of acquisition. Volumetric reconstruction inaccuracy was between 1.5% and 19.7% for precisely separated images and between 16.2% and 39.2% for fully freehand image acquisition. Rendered 3-D US vascular images clearly delineated vascular anatomy within the placenta and cord. Fully freehand 3-D US does have a role in off-line reconstruction of vascular anatomy, although variability in the z plane precludes its use for volumetric measurement. (E-mail: a.welsh@ic.ac.uk)

Binding occurs at early stages of processing in children and adults

Conjoining features in a high-rate serial presentation was studied in children and adults using event-related potentials. Three blocks of trials were run in which targets were defined by colour, by orientation or by a conjunction of colour and orientation. Only adults had faster RTs when detecting targets defined by a single feature than by a combination of features. Compared with adults, children had longer RTs, longer N1 and P2 latencies, and larger P1 and P2 amplitudes. Amplitudes asymmetries were consistent with differing cortical regions being implicated in the processing of colour and form. There were, however, no ERP latency effects as a function of task, suggesting that the binding of features proceeds in parallel with the processing of single features.

Down-regulated lymphoproliferation coincides with parasite maturation and with the collapse of both gamma interferon and interleukin-4 responses in a bovine model of onchocerciasis

Onchocerciasis is a debilitating parasitic infection caused by the filarial nematode Onchocerca volvulus. Infections are chronic, and persistence of the parasites for several years argues for highly adapted mechanisms of immune evasion. Due to the restricted host repertoire of O. volvulus, we have used the cattle parasite Onchocerca ochengi to investigate the nature of immunomodulation underpinning these long-term infections. Cattle were infected with a single inoculation of 350 infective-stage larvae under laboratory conditions (n = 6). Intradermal nodules containing immature adult worms were detected from 110 days postinfection, and microfilariae in skin were detected from day 280 postinfection. Parasite-specific responses during early infection were nonpolarized with respect to the major Th cytokines (interleukin-4 [IL-4], IL-2, and gamma interferon [IFN-gamma]) produced by antigen-stimulated peripheral blood mononuclear cells (PBMC) or serum antibody isotypes. Antigen-induced proliferation of PBMC peaked shortly after exposure and remained high during the prepatent infection. As the parasites matured and animals developed patent infections, there was a profound down-regulation of lymphoproliferation, accompanied by sharp falls in the expression of both IL-4 and IFN-gamma and a gradual decline in IL-2. Levels of immunoglobulin G2 (IgG2) fell, while those of IgG1 remained high. We conclude that neither a classical Th2 response nor a simple Th1-to-Th2 switch is sufficient to explain the immunomodulation associated with patent Onchocerca infections. Instead, there is an initial Th0 response, which matures into a response with some, but not all of the features of a Th2 response. The natural host-parasite relationship of O. ochengi in cattle may be useful as both a descriptive and predictive tool to test more refined models of immunomodulation in onchocerciasis.

Wolbachia bacteria in filarial immunity and disease

Lymphatic filarial nematodes are infected with endosymbiotic Wolbachia bacteria. Lipopolysaccharide from these bacteria is the major activator of innate inflammatory responses induced directly by the parasite. Here, we propose a mechanism by which Wolbachia initiates acute inflammatory responses associated with death of parasites, leading to acute filarial lymphangitis and adverse reactions to antifilarial chemotherapy. We also speculate that repeated exposure to acute inflammatory responses and the chronic release of bacteria, results in damage to infected lymphatics and desensitization of the innate immune system. These events will result in an increased susceptibility to opportunistic infections, which cause acute dermatolymphangitis associated with lymphoedema and elephantiasis. The recognition of the contribution of endosymbiotic bacteria to filarial disease could be exploited for clinical intervention by the targeting of bacteria with antibiotics in an attempt to reduce the development of filarial pathology.

Eyes first! Eye processing develops before face processing in children

Faces and eyes are critical social stimuli which adults process with ease, but how this expertise develops is not yet understood. Neural changes associated with face and eye processing were investigated developmentally using ERPs (N170), in 128 subjects (4-15 year olds and adults). Stimuli included upright faces to assess configural processing, eyes and inverted faces to assess feature-based processing. N170 was present in the youngest children with similar patterns of face sensitivity seen in adults. Development of N170 to upright faces continued until adulthood, suggesting slow maturation of configural processing. In contrast, N170 was shorter latency and much larger to eyes than faces in children and was mature by 11 years, suggesting the early presence of an eye detector, with a rapid maturational course.

Chemical pathology in brain white matter of recently detoxified alcoholics: a 1H magnetic resonance spectroscopy investigation of alcohol-associated frontal lobe injury

BACKGROUND

Investigations have suggested that frontal lobe abnormalities are a prominent feature of the alcoholic brain, indicated by impaired neuropsychological performance on tests of frontal lobe function and by reduced frontal lobe volume in neuroimaging and neuropathological examinations. White matter compartment volume loss may underlie observed brain shrinkage and cognitive deficits associated with the frontal lobes, although the nature of this change has not been well-characterized.

METHOD

To investigate the susceptibility of frontal lobe white matter to alcohol-associated metabolic change and to understand the nature of alcohol-related white matter injury, 1H magnetic resonance spectroscopy (MRS) was used to measure concentrations of metabolites in frontal white matter (FWM) and parietal white matter (PWM) of recently detoxified alcoholics (RDA) and nonalcoholic controls (CON). Concentrations of N-acetylaspartate (NAA), choline-containing compounds (Cho), myo-inositol (Ins), and creatine plus phosphocreatine (Cr) were measured in 37 RDA (mean age, 40.4 years; mean length of abstinence, 27.9 days) and 15 CON (mean age, 38.0 years).

RESULTS

Analysis of variance (ANOVA) revealed a group by region of interest interaction for concentrations of NAA. Simple effects analysis revealed a significant 14.7% reduction in FWM NAA, while NAA levels in PWM were similar in RDA and CON. In addition, RDA had an 11.8% increase (averaged across both regions of interest) in brain white matter Ins relative to CON. Reductions in FWM NAA were associated with a longer drinking history in the RDA group, but this result was not found when both age and drinking history were used to predict the level of FWM NAA.

CONCLUSIONS

Alcohol-associated reductions in FWM NAA may be the result of neuronal loss or dysfunction in the metabolism of NAA. While alcohol-induced oxidative stress may cause global brain impairments in the metabolism and subsequent reduction of NAA, the frontal lobes are particularly rich in excitatory amino acid pathways, and axonal damage or destruction secondary to glutamate-mediated excitotoxicity during alcohol withdrawal may cause frontal lobe-specific reductions in NAA. Elevations in brain white matter Ins may reflect astrocyte proliferation as well as an osmotic response to cell shrinkage.

Regional cerebral blood flow in cocaine- versus methamphetamine-dependent patients with a history of alcoholism

Although abuse of cocaine or methamphetamine usually takes place in the context of heavy drinking, there is little information on the effects of such substance use comorbidity on brain perfusion. We explored similarities and differences in the effects of these two drugs in combination with alcohol on brain function using SPECT. Global and regional cerebral blood flow (CBF) were examined in 7 abstinent cocaine-dependent alcoholics (CDA; mean age = 39.2 yr, S.D. = 9.2 yr), 7 abstinent methamphetamine-dependent alcoholics (MDA; mean age = 36.8 yr, S.D. = 5.0 yr), and 7 non-alcoholic/non-stimulant abusing controls (NAC; mean age = 37.3 yr, S.D. = 9.6 yr). MDA had significantly lower global CBF than CDA who, in turn, were significantly lower than NAC. In addition, CDA had abnormal perfusion in the superior posterior frontal region compared to NAC; while MDA did not display specific regional deficits. Therefore, it appears that cocaine alters the relationship between global and regional CBF in alcoholics, while methamphetamine does not.