Dextrin–rhEGF conjugates as bioresponsive nanomedicines for wound repair

Growth factors are known to act in concert to promote wound repair, but their topical application rarely leads to a significant clinical improvement of chronic wounds due to premature inactivation in wound environment. The aim of this study was to synthesise a polymer–growth factor conjugate and investigate whether the novel concept called Polymer-masking-UnMasking-Protein Therapy (PUMPT) might be used to generate bioresponsive polymer therapeutics as nanomedicines able to promote tissue repair. Succinoylated dextrin ( 85,000 g/mol;  19 mol% succinoylation), and rhEGF were chosen as a first model combination. The conjugate synthesised contained  16%wt rhEGF and < 1% free protein. It exhibited increased stability towards proteolytic degradation by trypsin and the clinically relevant enzyme neutrophil elastase. The dextrin component was degraded on addition of α-amylase leading to sustained release of free rhEGF over time (52.7% release after 168 h). When biological activity was assessed (± α-amylase) in proliferation assays using epidermoid carcinoma (HEp2) cells and HaCaT keratinocytes, as anticipated, polymer conjugation reduced rhEGF bioactivity (p = 0.0035). However, exposure to physiological concentrations of α-amylase triggered dextrin degradation and this led to protein unmasking with restoration of bioactivity to the level seen for unmodified rhEGF. Indeed, prolongation of HEp2 proliferation was observed over 8 days. The inability of dextrin, succinoylated dextrin or α-amylase alone to induce proliferative effects, and the ability of α-amylase-exposed dextrin–rhEGF to induce phosphorylation of the epidermal growth factor receptor (EGFR) in HEp2 cells confirmed a mechanism of action by stimulation of classical signal transduction pathways. These observations suggest that this dextrin–rhEGF, and other dextrin-growth factor conjugates have potential for further development as bioresponsive nanomedicines for tissue repair.     

The acute impact of ingestion of breads of varying composition on blood glucose, insulin and incretins following first and second meals

Structural characteristics and baking conditions influence the metabolic responses to carbohydrate-containing foods. We hypothesized that consumption of whole wheat or sourdough breads would have a favourable effect on biomarkers of glucose homeostasis after first and second meals, compared with those for white bread. Ten overweight volunteers consumed 50 g available carbohydrate of each of the four breads (white, whole wheat, sourdough, whole wheat barley) followed 3 h later by a standard second meal. Blood was sampled for 3 h following bread ingestion and a further 2 h after the second meal for determination of glucose, insulin, paracetamol (indirect marker of gastric emptying), glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1). Glucose and GLP-1 responses to sourdough bread were lower (P < 0.05) than whole wheat and whole wheat barley breads. Glucose area under the curve (AUC) for sourdough bread was lower than those for whole wheat (P < 0.005) and whole wheat barley (P < 0.03) breads for the entire study. GIP AUC after sourdough bread ingestion was lower compared to white (P < 0.004) and whole wheat barley (P < 0.002) breads following the second meal. There were no significant differences in insulin and paracetamol concentrations among the test breads. Ultra-fine grind whole wheat breads did not result in postprandial responses that were lower than those of white bread, but sourdough bread resulted in lower glucose and GLP-1 responses compared to those of these whole wheat breads following both meals.     

Broadening the age restriction for initiating rotavirus vaccination in regions with high rotavirus mortality: Benefits of mortality reduction versus risk of fatal intussusception

Introduction

Recently developed rotavirus vaccines have the potential to reduce diarrhea mortality in children in developing countries. Available data to date do not indicate risk of intussusception with these new vaccines. To avoid a potential unanticipated risk post-licensure, it is recommended that rotavirus immunization be initiated before 12 weeks of age when background intussusception rates are low. This policy could exclude a substantial number of children from vaccination, especially in developing countries where delays in vaccination are common.

Methods

We conducted a scenario analysis to assess the potential benefits of mortality reduction from rotavirus versus the risk of fatal intussusception when the first dose of the vaccine is strictly administered by 12 weeks of age compared with a free strategy with vaccine administered before 1 year of age using data on rotavirus disease, vaccine safety and efficacy, and current diphtheria–tetanus–pertussis vaccination rates, and by incorporating hypothetical risks of intussusception.

Results

In developing countries, assuming vaccine efficacy of 50% and 75% for doses 1 and 2, respectively, and a hypothetical sixfold and threefold increased relative risk of intussusception within 7 days of doses 1 and 2, respectively, initiating rotavirus immunization before 12 weeks of age would prevent 194,564 of the 517,959 annual rotavirus-associated deaths among children <5 years, while potentially resulting in 1106 fatal intussusception events. Administration of the first dose to infants up to 1 year of age would prevent an additional 54,087 rotavirus-associated deaths (total = 248,651) while potentially resulting in an additional 1226 intussusception deaths (total = 2332).

Conclusion

In developing countries, the additional lives saved by broadening the age restrictions for initiation of rotavirus vaccination would far outnumber the hypothetical excess intussusception deaths that would accompany such an approach.     

Noninvasive measurement of the cerebral blood flow response in human lateral geniculate nucleus with arterial spin labeling fMRI

To date, functional magnetic resonance imaging (fMRI) studies of the lateral geniculate nucleus (LGN) have primarily focused on measures of the blood oxygenation level dependent (BOLD) signal. Arterial spin labeling (ASL) is an MRI method that can provide direct measures of functional cerebral blood flow (CBF) changes. Because CBF is a well-defined physiological quantity that contributes to BOLD contrast, CBF measures can be used to improve the quantitative interpretation of fMRI studies. However, due in part to the low intrinsic signal-to-noise ratio of the ASL method, measures of functional CBF changes in the LGN are challenging and have not previously been reported. In this study, we demonstrate the feasibility of using ASL fMRI to measure the CBF response of the LGN to visual stimulation on a 3 T MRI system. The use of background suppression and physiological noise reduction techniques allowed reliable detection of LGN activation in all five subjects studied. The measured percent CBF response during activation ranged from 40 to 100%, assuming no interaction between the left and right LGN.     

Psychogenic nonepileptic seizures in patients with learning disability: comparison with patients with no learning disability

Among a consecutive series of patients with psychogenic nonepileptic seizures (PNES), we compared patients with learning disability (LD) (n=25) with patients with no LD (n=263), with respect to demographic and clinical variables. A higher proportion of the LD group had epilepsy as well as PNES (P<0.001) (uncorrected P values are quoted), and a higher proportion were taking antiepileptic drugs at the time of diagnosis of PNES (P=0.007). Fewer patients with LD had a history of antecedent sexual abuse (P=0.036). A higher proportion of the LD group had previous pseudostatus (P<0.001), and a higher proportion had immediate situational or emotional triggers for their attacks (P<0.001). There were trends toward a higher proportion of men in the LD group (P=0.056) and a longer delay between onset of PNES and diagnosis (P=0.072). Our data suggest potentially important clinical differences between PNES populations with and without LD, as well as possible differences in mechanism.     

The progression of behavior in dementia: an in-office guide for clinicians

This article examines the progression of behavioral changes in 200 community living and long term care patients using the Kingston Standardized Behavioral Assessment, a measure of traditional neuropsychiatric behaviors (behavioral and psychological symptoms of dementia) and neuropsychological behaviors. A group of patients diagnosed with probable Alzheimer's disease or mixed dementia (Alzheimer's disease and vascular dementia), was assessed using the Kingston Standardized Behavioral Assessment, ranked by total Kingston Standardized Behavioral Assessment score and were divided into quartile-based groups. The scores revealed changes in behavior patterns across quartiles. Significant behavior change appeared even in quartile one. Lower scores were predominantly associated with neuropsychological behaviors; as scores increased, neuropsychiatric behaviors became equally common. An at-a-glance guide characterizing the patterns of increasing behavioral change is provided for clinicians. Behavioral changes appear both early and throughout dementia; the type and pattern of these emerging behaviors change as the disease progresses. Clinicians can use the typical patterns of behavioral change to identify behavioral impairment in individual patients and anticipate future changes and related care needs.     

Increased procoagulant cell-derived microparticles (C-MP) in splenectomized patients with ITP

Background: Splenectomy is frequently employed for therapeutic and diagnostic purposes in various clinical disorders. However its long-term safety is not well elucidated. Although risk of infection by encapsulated organisms is widely recognized, less well-known are risks of thrombosis and cardiovascular disease. Methods: We investigated levels of cell-derived microparticles (C-MP) in 23 splenectomized ITP (ITP-S) and 53 unsplenectomized ITP patients (ITP-nS). Assay of C-MP derived from platelets (PMP), leukocytes (LMP), red cells (RMP) and endothelial cells (EMP) were performed by flow cytometry. Coagulation parameters included PT, aPTT and activities of FVIII, IX and XI. Results of all measures were compared between the two groups, ITP-S vs ITP-nS. Results: Levels of all C-MP were higher in ITP-S than ITP-nS but only RMP and LMP reached statistical significance (p = 0.0035 and p < 0.0001, respectively). The aPTT was significantly shorter in ITP-S (p = 0.029). Interestingly, correlation analysis revealed that RMP, but not other C-MP, were associated with shortening of aPTT (p = 0.024) as well as with increased activities of factors VIII (p = 0.023), IX (p = 0.021) and XI (p = 0.0089). Conclusions: RMP and LMP were significantly elevated in splenectomized compared to non-splenectomized ITP patients. This suggests that the spleen functions to clear procoagulant C-MP, and that elevation of C-MP might contribute to increased risk of thrombosis, progression of atherosclerosis and cardiovascular disease following splenectomy.     

Imaging language pathways predicts postoperative naming deficits

Naming difficulties are a well recognised, but difficult to predict, complication of anterior temporal lobe resection (ATLR) for refractory epilepsy. We used MR tractography preoperatively to demonstrate the structural connectivity of language areas in patients undergoing dominant hemisphere ATLR. Greater lateralisation of tracts to the dominant hemisphere was associated with greater decline in naming function. We suggest that this method has the potential to predict language deficits in patients undergoing ATLR.     

A graded forceps crush spinal cord injury model in mice

Given the rising availability and use of genetically modified animals in basic science research, it has become increasingly important to develop clinically relevant models for spinal cord injury (SCI) for use in mice. We developed a graded forceps crush model of SCI in mice that uses three different forceps with spacers of 0.25, 0.4, and 0.55 mm, to produce severe, moderate, and mild injuries, respectively. Briefly, each mouse was subjected to laminectomy of T5-T7, 15-second spinal cord crush using one of those forceps, behavioral assessments, and post-mortem neuroanatomical analyses. There were significant differences among the three injury severity groups on behavioral measures (Basso Mouse Score, footprint, and ladder analyses), demonstrating an increase in neurological deficits for groups with greater injury severity. Quantitative analysis of the lesion demonstrated that as injury severity increased, lesion size and GFAP negative area increased, and spared tissue, spinal cord cross-sectional area, spared grey matter and spared white matter decreased. These measures strongly correlated with the behavioral outcomes. Similar to other studies of SCI in mice, we report a dense laminin and fibronectin positive extracellular matrix in the lesion sites of injured mice, but unlike those previous studies, we also report the presence of numerous p75 positive Schwann cells in and around the lesion epicenter. These results provide evidence that the graded forceps crush model is an attractive alternative for the study of SCI and related therapeutic interventions. Because of its demonstrated consistency, ease of use, low cost, and clinical relevance, this graded forceps crush is an attractive alternative to the other mouse models of SCI currently available.