Incrementing the Frequency of Dynamic Strain on SMC-Cellularised Collagen-Based Scaffolds Affects Extracellular Matrix Remodeling and Mechanical Properties

Notwithstanding the efforts injected in vascular tissue engineering in the past 30 years, the clinical translation of engineered artery constructs is far from being successful. One common approach to improve artery regeneration is the use of cyclic mechanical stimuli to guide cellular remodeling. However, there is a lack of information on the effect of cyclic strain on cells within a 3D environment. To this end, this work explored the effect of gradual increase in stimulation frequency on the response of human umbilical artery smooth muscle cells (HUASMCs) embedded in a 3D collagen matrix. The results demonstrate that, with an applied strain of 5%, the gradual increase of frequency from 0.1 to 1 Hz improved collagen remodeling by HUASMCs compared to samples constantly stimulated at 1 Hz. The expression of collagen, elastin and matrix metalloproteinase-2 (MMP-2) genes was similar at 7 days for gradual and 1 Hz samples which showed lower amounts than static counterparts. Interestingly the mechanical properties of the constructs, specifically the amplitude of the time constants and the elastic equilibrium modulus, were enhanced by gradual increase of frequency. Taken together, these results show an increase in collagen remodeling by the HUASMCs overtime under incremental cyclic mechanical strain. This work suggests that only the in-depth investigation of the effects of stimulation parameters on the behavior of vSMC under cyclic strain in a 3D environment could lead to the design of optimized control strategies for enhanced vascular tissue generation and maturation in bioreactors.

Unraveling the role of mechanical stimulation on smooth muscle cells: A comparative study between 2D and 3D models

A thorough understanding of cell response to combined culture configuration and mechanical cues is of paramount importance in vascular tissue engineering applications. Herein, we investigated and compared the response of vascular smooth muscle cells (vSMCs) cultured in different culture environments (2D cell monolayers and 3D cellularized collagen-based gels) in combination with mechanical stimulation (7% uniaxial cyclic strain, 1 Hz) for 2 and 5 days. When cyclic strain was applied, two different responses, in terms of cell orientation and expression of contractile-phenotype proteins, were observed in 2D and 3D models. Specifically, in 2D configuration, cyclic strain caused ∼50% of cell population to align nearly perpendicular (80-90 degrees) to the strain direction, while not influencing the contractile-phenotype protein expression, as compared to the 2D static controls. Conversely, the application of uniaxial strain to 3D constructs induced a ∼60% cell alignment almost parallel (0-10 degrees) to the strain direction. Moreover, 3D mechanical stimulation applied for 5 days induced a twofold increase of SM α-actin level and a 14-fold increase of calponin expression as compared to 3D static controls. Altogether these findings provide a new insight into the potential to drive cell behavior by modulating the extracellular matrix and the biomechanical environment. Biotechnol. Bioeng. 2016;113: 2254-2263. © 2016 Wiley Periodicals, Inc.

Dementia in Parkinson's disease: a 20-year neuropsychological study (Sydney Multicentre Study)

OBJECTIVE

To determine whether neuropsychological measures differ between patients with idiopathic Parkinson's disease (PD) who acquire dementia within 10 years of disease onset versus those who acquire dementia later in the disease course, using data from the longitudinal Sydney Multicentre Study of PD.

METHODS

The Sydney Multicentre Study of PD is a cohort of 149 community-living de novo patients with idiopathic PD studied over a 20-year period. Detailed clinical and neuropsychological tests were administered at baseline and at 3, 5, 10, 15 and 20 years, and the dementia status was assessed at each time point. For the present study, the pattern of longitudinal neuropsychological measures was compared between PD patients with the onset of dementia in the middle (5-10 years, mid-stage PD dementia, N = 20) or late (>10 years, late-stage PD dementia, N = 10) disease stages using analysis of variance and multiple linear regression modelling, and the relationship between age and dementia onset assessed using survival statistics.

RESULTS

Mid-stage PD dementia patients were differentiated from late-stage PD dementia patients by having greater deficits in vocabulary skills prior to and at dementia onset. The pattern of cognitive deficits following dementia onset are similar, and there is no difference in the age of dementia onset between the different PD groups.

CONCLUSIONS

These data suggest that the evolution of dementia within PD occurs at around 70 years of age, regardless of the time of PD onset, and affects cognitive domains in a similar way, although patients with earlier-onset PD have a preserved linguistic ability prior to dementia onset.

Galantamine for Alzheimer's disease and mild cognitive impairment

BACKGROUND

Galantamine is a specific, competitive, and reversible acetylcholinesterase inhibitor.

OBJECTIVES

To assess the clinical effects of galantamine in patients with mild cognitive impairment (MCI), probable or possible Alzheimer's disease (AD), and potential moderators of effect.

SEARCH STRATEGY

The trials were identified from a search of the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group, last updated on 25 April 2005 using the terms galanthamin*, galantamin* and Reminyl. Published reviews were inspected for further sources. Additional information was collected from unpublished clinical research reports for galantamine obtained from Janssen and from http://www.clinicalstudyresults.org/.

SELECTION CRITERIA

Trials selected were randomised, double-blind, parallel-group comparisons of galantamine with placebo for a treatment duration of greater than 4 weeks in subjects with MCI or AD.

DATA COLLECTION AND ANALYSIS

Data were extracted independently by the reviewers and pooled where appropriate and possible. Outcomes of interest include the clinical global impression of change (CIBIC-plus or CGIC), Alzheimer's Disease Assessment Scale-cognitive sub scale (ADAS-cog), Alzheimer's Disease Cooperative Study/Activities of Daily Living (ADCS-ADL), Disability Assessment for Dementia scale (DAD) and Neuropsychiatric Inventory (NPI). Potential moderating variables of treatment effect assessed included trial duration, dose, and diagnosis of possible versus probable Alzheimer's disease.

MAIN RESULTS

Ten trials with a total 6805 subjects were included in the analysis. Treatment with galantamine led to a significantly greater proportion of subjects with improved or unchanged global rating scale rating (k = 8 studies), at all dosing levels except for 8 mg/d . Confidence intervals for the ORs overlapped across the dose range of 16 mg to 36 mg per day, with point estimates of 1.6 - 1.8 when analysed with the intention-to-treat sample. Treatment with galantamine also led to significantly greater reduction in ADAS-cog score at all dosing levels (k = 8), with greater effect over six months compared to three months. Confidence intervals again overlapped. Point estimate of effect was lower for 8 mg/d but similar for 16 mg to 36 mg per day. For example, treatment effect for 24 mg/d over six months was 3.1 point reduction in ADAS-cog (95%CI 2.6-3.7, k = 4, ITT).ADCS-ADL, DAD and NPI were reported only in a small proportion of trials: all showed significant treatment effect in some individual trials at least. Confidence interval of treatment effect for the one trial recruiting patients with possible AD overlapped with the other seven recruiting patients with probable AD. Galantamine's adverse effects appeared similar to those of other cholinesterase inhibitors and to be dose related. Prolong release / once daily formulation of galantamine at 16 - 24mg/d was found to have similar efficacy and side-effect profile as the equivalent twice-daily regime. Data from the two MCI trials suggest marginal clinical benefit, but a yet unexplained excess in death rate.

AUTHORS' CONCLUSIONS

Subjects in these trials were similar to those seen in earlier anti dementia AD trials, consisting primarily of mildly to moderately impaired outpatients. Galantamine's effect on more severely impaired subjects has not yet been assessed.Nevertheless, this review shows consistent positive effects for galantamine for trials of three to six months' duration. Although there was not a statistically significant dose-response effect, doses above 8 mg/d were, for the most part, consistently statistically significant. Galantamine's safety profile in AD is similar to that of other cholinesterase inhibitors with respect to cholinergically mediated gastrointestinal symptoms. It appears that doses of 16 mg/d were best tolerated in the single trial where medication was titrated over a four week period, and because this dose showed statistically indistinguishable efficacy with higher doses, it is probably most preferable initially. Longer term use of galantamine has not been assessed in a controlled fashion. Galantamine use in MCI is not recommended due to its association with an excess death rate.

Galantamine for Alzheimer's disease

BACKGROUND

Galantamine is a specific, competitive, and reversible acetylcholinesterase inhibitor.

OBJECTIVES

To assess the clinical effects of galantamine in patients with probable or possible Alzheimer's disease (AD), and potential moderators of effect.

SEARCH STRATEGY

The trials were identified from a search of the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group, last updated on 25 August 2005 using the terms galanthamin*, galantamin* and Reminyl. Published reviews were inspected for further sources. Additional information was collected from unpublished clinical research reports for galantamine obtained from Janssen.

SELECTION CRITERIA

Trials selected were randomised, double-blind, parallel-group comparisons of galantamine with placebo for a treatment duration of greater than 4 weeks in subjects with AD.

DATA COLLECTION AND ANALYSIS

Data were extracted independently by the reviewers and pooled where appropriate and possible. Outcomes of interest include the clinical global impression of change (CIBIC-plus or CGIC), Alzheimer's Disease Assessment Scale-cognitive sub scale (ADAS-cog), Alzheimer's Disease Cooperative Study/Activities of Daily Living (ADCS-ADL), Disability Assessment for Dementia scale (DAD) and Neuropsychiatric Inventory (NPI). Potential moderating variables of treatment effect assessed included trial duration, dose, and diagnosis of possible vs. probable Alzheimer's disease.

MAIN RESULTS

Seven trials with a total 3777 subjects were included in the analysis. Treatment with galantamine led to a significantly greater proportion of subjects with improved or unchanged global rating scale rating (k=7), at all dosing levels except for 8mg/d . Confidence intervals for the ORs overlapped across the dose range of 16mg to 36mg per day, with point estimates of 1.6-2.1 when analysed with the intention-to-treat sample. Treatment with galantamine also led to significantly greater reduction in ADAS-cog score at all dosing levels (k=7), with greater effect over 6 months compared to 3 months. Confidence intervals again overlapped. Point estimate of effect was lower for 8mg/d but similar for 16mg to 36mg per day. For example, treatment effect for 24mg/d over 6 months was 3.1point reduction in ADAS-cog (95%CI 2.6-3.7, k=4, ITT).ADCS-ADL, DAD and NPI were reported only in a small proportion of trials: all showed significant treatment effect in some individual trials at least. Confidence interval of treatment effect for the one trial recruiting patients with possible AD overlapped with the other six recruiting patients with probable AD. Galantamine's adverse effects appeared similar to those of other cholinesterase inhibitors and to be dose related.

REVIEWERS' CONCLUSIONS

Subjects in these trials were similar to those seen in earlier anti dementia AD trials, consisting primarily of mildly to moderately impaired outpatients. Galantamine's effect on more severely impaired subjects has not yet been assessed.Nevertheless, this review shows consistent positive effects for galantamine for trials of 3 to 6 months duration. Although there was not a statistically significant dose-response effect, doses above 8mg/d were, for the most part, consistently statistically significant. Galantamine's safety profile is similar to that of other cholinesterase inhibitors with respect to cholinergically mediated gastrointestinal symptoms. It appears that doses of 16 mg/d were best tolerated in the single trial where medication was titrated over a 4 week period, and because this dose showed statistically indistinguishable efficacy with higher doses, it is probably most preferable initially. Longer term use of galantamine has not been assessed in a controlled fashion.

Accuracy of combined breast imaging in young women

This is a study of the accuracy of combined breast imaging (mammography and ultrasound) in young women with breast symptoms. We performed an appraisal of the literature, and improved our study design by avoiding biases identified in published work. Our study presents the sensitivity and specificity of mammography and breast ultrasound, individually and in combination, using different thresholds for categorizing test results, in a population of consecutive women. We show that combining the two imaging tests does improve sensitivity without significantly reducing test specificity. However, the number of additional cancers correctly identified using combined imaging, relative to the number of false positives, is highly dependent on breast cancer prevalence.

Recognition and invasion of human skin by Schistosoma mansoni cercariae: the key-role of L-arginine

The attachment of Schistosoma mansoni cercariae to mammalian skin is specifically stimulated by L-arginine. As L-arginine is an unsuitable signal for a specific identification of mammalian skin we examined the following 5 hypotheses to explain the advantage of the cercarial sensitivity to L-arginine. (1) A Schistosoma infection lowered the arginine concentration in the serum of mice, and this could enable the cercariae to avoid attachments to already infected mice. However, the infection did not reduce the arginine concentration in the skin and the cercarial attachment responses to it. (2) Creeping cercariae showed chemotactic orientation specifically along increasing L-arginine gradients. L-arginine could act as a pheromone which could guide cercariae towards common penetration sites. However, the cercarial acetabular gland contents were not attractive and they did not (in contrast to previous reports) contain much arginine. (3) Schistosomula (transformed cercariae) could use L-arginine to produce nitric oxide (NO) for blood vessel dilation during their migration in the host. However, in vitro the transformed cercariae did not convert L-arginine into citrulline and NO. (4) Schistosomula could bind L-arginine from the surrounding tissues and so escape the cellular immune attack (which needs L-arginine as the precursor of NO). However, transformed cercariae bound no more L-arginine than L-serine and L-lysine. (5) Schistosomula, migrating parallel to the surface in the mammalian epidermis, are dependent on information on their position between the inner and the surface layers of the skin. In the mouse skin, they adjusted their body axis with the ventral side toward the deeper (arginine-residue rich) epidermis layers. When migrating in agar, they showed chemo-orientation toward serum, and D-glucose and L-arginine were the stimulating compounds therein. The burrowing schistosomula adjusted their body axis (as in the epidermis) with the ventral side toward the higher concentration of L-arginine and not of glucose. We argue that the sensitivity for L-arginine has its primary function in orientation within mammalian skin and in location of blood vessels.

Prevalence of cercariae from Lymnaea stagnalis snails in a pond system in Southern Germany

Lymnaea stagnalis snails were collected from 174 individual ponds of an extensive pond system in South Germany; 43,441 snails collected during 1980 2000 were examined for shedding cercariae. The species richness (at least 18 species of cercariae) and the high cercarial prevalence (at least 44.9%) may result from the high abundance and diversity of vertebrate and invertebrate hosts in the area. The mean prevalence (% +/- SEM) of most cercarial species increased from May-June to August-October, e.g. in Diplostomum spathaceum from 4.1% to 18.6%, in all echinostomatids from 5.6% to 18.0%, in Pseudechinoparyphium echinatum from 3.0% to 11.2%, in Xiphidiocercariae from 2.2% to 13.4%, and the overall prevalence shifted from 13.7% to 53.5%. There was no change in the prevalence of the different cercarial species over the last 20 years. The agents of cercarial dermatitis showed a constant low prevalence, 0.17% in Trichobilharzia ocellata (43,441 L. stagnalis examined) and 0.24% in other Trichobilharzia species (4,245 Radix examined). Such low prevalences seem to be normal in areas where cercarial dermatitis occurs in humans.

Recognition of cattle skin by cercariae of Orientobilharzia turkestanica

The cercariae of Orientobilharzia turkestanica attached to isolated cattle skin and penetrated it. The attachment was stimulated by warmth and by hydrophilic and lipophilic chemical cues of skin surface extracts. The enduring contact with the skin was also stimulated by the chemical cues, but not by warmth. Penetration of the cercariae into agar substrates was triggered by skin surface lipids, and free fatty acids were identified as the exclusively active compounds of the lipids. That the cercariae attach and remain on the skin by responding to at least two different chemical host cues is unique among the schistosomatids studied so far. It might reflect an adaptation to invade the hosts in clear water or near the water surface where chemical mud compounds will not interfere with host recognition.

Photo- and geo-orientation by Echinostome cercariae results in habitat selection

The effect of light and gravity on orientation was studied in cercariae of 4 echinostome species: Pseudechinoparyphium echinatum, Echinostoma revolutum, Hypoderaeum conoideum, and Isthmiophora melis. The cercariae were placed into vertical and horizontal cuvettes, illuminated with 2 different light intensities from various directions, and their distribution recorded for 6 hr Each species showed its individual pattern of horizontal photo-orientation and geo-orientation, with distinct changes during the time after emerging. The geo-orientation was controlled differently in each species by the intensity and the direction of light radiation. The different orientation patterns suggest functions such as leaving the habitats of the host-snails emitting the cercariae, dispersal, and frequenting the microhabitats of potential hosts. The high diversity of orientation patterns among the species that originated from the same first intermediate host Lymnaea stagnalis in the same ponds and that invade similar host spectra suggests adaptations to different ecological conditions.

Effect of immersion of biopsy forceps in formalin on tissue urease activity

BACKGROUND AND AIMS

It is routine practice to wash biopsy forceps that have been immersed in formalin solution before taking gastric biopsies to test for urease activity as formalin is thought to inactivate the urease enzyme. The aim of this study was to assess the effect of pre-immersion of biopsy forceps in formalin solution on the ability to detect Helicobacter pylori urease activity in biopsies obtained with the same forceps.

METHODS

Two hundred consecutive patients undergoing gastroscopy who had macroscopic evidence of possible H. pylori infection had an initial antral biopsy taken using sterile forceps for determining biopsy urease activity. The same forceps were then used to obtain an antral biopsy for histological examination. The forceps were then used, without washing off any adherent formalin solution, to obtain a further antral biopsy for urease testing.

RESULTS

The concordance rate for urease tests, with or without formalin exposure, was 100% (95% confidence interval (CI) 98.2-100%). Fifty-six of 200 patients (28%) were found to have urease-positive biopsies. Of these, 52/56 (92.9%) had identifiable H. pylori on histopathology. One hundred and forty-four of 200 patients (72%) were found to have urease-negative biopsies. Of these, seven (4.9%) had identifiable H. pylori on histopathology. Six of seven (85.7%) had only a small number of organisms identified. The sensitivity and specificity for the urease test compared with the histopathology as a reference standard was 88.1% (95% CI 79.9-96.4%) and 97.2% (95% CI 94.4-99.9%), respectively.

CONCLUSION

Immersion of biopsy forceps in formalin did not reduce the ability to detect urease activity in gastric biopsies taken subsequently.

Schistosoma mansoni cercariae: stimulation of acetabular gland secretion is adapted to the chemical composition of mammalian skin

The chemical signals of mammalian skin that stimulate the secretion of acetabular gland contents of Schistosoma mansoni cercariae were determined by exposing cercariae to fractions of human and pig skin surface obtained by thin-layer chromatography. Postacetabular gland secretion was stimulated by hydrophilic skin extracts but was often combined with a secretion of preacetabular glands. Secretion of preacetabular glands, which contain enzymes for skin lysis, could be selectively stimulated with skin surface lipids. Two different mechanisms of lipid-stimulated preacetabular gland release could be distinguished. First, secretion in combination with penetration behavior and probably tegument transformation was stimulated by the fraction of free fatty acids. Second, secretion independent of penetration behavior and tegument transformation was exclusively stimulated by glucosylceramides and phospholipids, probably phosphatidylcholines. The secretion mechanisms seem to allow a continuous lysis of epidermal macromolecules during the skin passage of the cercariae. Free fatty acids occur in the uppermost skin layers and may stimulate the combination of the first response; phospholipids and glucosylceramides are restricted to deeper epidermal layers and may stimulate the enzyme secretion there. An active preacetabular gland release was also stimulated by toxic chemicals, which could suggest an emergency penetration program for impaired cercariae.