The impact of size on particle drainage dynamics and antibody response

Vaccine-induced immune response can be greatly enhanced by mimicking pathogen properties. The size and the repetitive geometric shape of virus-like particles (VLPs) influence their immunogenicity by facilitating drainage to secondary lymphoid organs and enhancing interaction with and activation of B cells and innate humoral immune components. VLPs derived from the plant Bromovirus genus, specifically cowpea chlorotic mottle virus (CCMV), are T = 3 icosahedral particles. (T) is the triangulation number that refers to the number and arrangements of the subunits (pentamers and hexamers) of the VLPs. CCMV-VLPs can be easily expressed in an E. coli host system and package ssRNA during the expression process. Recently, we have engineered CCMV-VLPs by incorporating the universal tetanus toxin (TT) epitope at the N-terminus. The modified CCMV_TT-VLPs successfully form icosahedral particles T = 3, with a diameter of ~30 nm analogous to the parental VLPs. Interestingly, incorporating TT epitope at the C-terminus of CCMV_TT-VLPs results in the formation of Rod-shaped VLPs, ~1 μm in length and ~ 30 nm in width. In this study, we have investigated the draining kinetics and immunogenicity of both engineered forms (termed as Round-shaped CCMV_TT-VLPs and Rod-shaped CCMV_TT-VLPs) as potential B cell immunogens using different in vitro and in vivo assays. Our results reveal that Round-shaped CCMV_TT-VLPs are more efficient in draining to secondary lymphoid organs to charge professional antigen-presenting cells as well as B cells. Furthermore, compared to Rod-shaped CCMV_TT-VLPs, Round-shaped CCMV_TT-VLPs led to more than 100-fold increased systemic IgG and IgA responses accompanied by prominent formation of splenic germinal centers. Round-shaped CCMV_TT-VLPs could also polarize the induced T cell response toward Th1. To our knowledge, this is the first study investigating and comparing the draining kinetics and immunogenicity of one and the same VLP monomer forming nano-sized icosahedra or rods in the micrometer size.

Radiological outcome after treatment of juvenile flatfeet with subtalar arthroereisis: a matched pair analysis of 38 cases comparing neurogenic and non-neurogenic patients

PURPOSE

Therapy of juvenile neurogenic flatfoot (JNF) with subtalar arthroereisis (SA) is currently under critical clinical investigation. In this retrospective matched pair analysis, the radiological outcome after arthroereisis in paediatric patients with infantile cerebral palsy and JNF was compared with children with juvenile flatfeet (JF) without neurological diseases.

METHODS

From October 2007 to April 2018 80 patients with 149 flatfeet underwent surgery with SA. Inclusion criteria were: 1) JNF or JF with age at surgery ≤ 13 years; 2) treatment with SA; 3) presence of three sets of biplane radiographs (preoperative, postoperative and follow-up (FU)). The radiographs were analyzed for: 1) navicular-cuboidal-index (NCI); 2) talocalcaneal angle anteroposterior; 3) talocalcaneal angle lateral; 4) calcaneal-pitch (CP); and 5) talometatarsal-index (TMTI). Following this, 25 patients with 38 flatfeet could be included.

RESULTS

The mean age at SA of the JNF group was 9.2 years (JF group: 9.3 years) and the mean time of FU was 35.2 months (JF group: 39.4 months). In comparison with preoperatively, a significant decrease of the NCI was seen in both groups (p = ≤ 0.05 and p = ≤ 0.001) in the FU radiographs. The analysis of CP and TMTI in the JF group also resulted in a significant improvement (p = ≤ 0.001 and p = ≤ 0.05). Overall, the comparison between the JNF and JF group showed no significant differences in regard to the analyzed postoperative parameters.

CONCLUSION

Based on this data, treatment of flatfeet by SA in patient with neurological disorders shows an improvement of radiological parameters comparable with neurologically unimpaired patients and might be considered as additional treatment option.

LEVEL OF EVIDENCE

IV.

Vaccination with nanoparticles combined with micro-adjuvants protects against cancer

BACKGROUND

Induction of strong T cell responses, in particular cytotoxic T cells, is a key for the generation of efficacious therapeutic cancer vaccines which yet, remains a major challenge for the vaccine developing world. Here we demonstrate that it is possible to harness the physiological properties of the lymphatic system to optimize the induction of a protective T cell response. Indeed, the lymphatic system sharply distinguishes between nanoscale and microscale particles. The former reaches the fenestrated lymphatic system via diffusion, while the latter either need to be transported by dendritic cells or form a local depot.

METHODS

Our previously developed cucumber-mosaic virus-derived nanoparticles termed (CuMV_TT-VLPs) incorporating a universal Tetanus toxoid epitope TT830-843 were assessed for their draining kinetics using stereomicroscopic imaging. A nano-vaccine has been generated by coupling p33 epitope as a model antigen to CuMV_TT-VLPs using bio-orthogonal Cu-free click chemistry. The CuMV_TT-p33 nano-sized vaccine has been next formulated with the micron-sized microcrystalline tyrosine (MCT) adjuvant and the formed depot effect was studied using confocal microscopy and trafficking experiments. The immunogenicity of the nanoparticles combined with the micron-sized adjuvant was next assessed in an aggressive transplanted murine melanoma model. The obtained results were compared to other commonly used adjuvants such as B type CpGs and Alum.

RESULTS

Our results showed that CuMV_TT-VLPs can efficiently and rapidly drain into the lymphatic system due to their nano-size of ~ 30 nm. However, formulating the nanoparticles with the micron-sized MCT adjuvant of ~ 5 μM resulted in a local depot for the nanoparticles and a longer exposure time for the immune system. The preclinical nano-vaccine CuMV_TT-p33 formulated with the micron-sized MCT adjuvant has enhanced the specific T cell response in the stringent B16F10p33 murine melanoma model. Furthermore, the micron-sized MCT adjuvant was as potent as B type CpGs and clearly superior to the commonly used Alum adjuvant when total CD8⁺, specific p33 T cell response or tumour protection were assessed.

CONCLUSION

The combination of nano- and micro-particles may optimally harness the physiological properties of the lymphatic system. Since the nanoparticles are well defined virus-like particles and the micron-sized adjuvant MCT has been used for decades in allergen-specific desensitization, this approach may readily be translated to the clinic.

Testing wound dressings using an in vitro wound model

OBJECTIVE

To determine whether or not there are any significant differences in the effects of wound dressings on bacterial bioburden.

METHOD

A selection of non-occlusive, non-adhesive dressings was tested for their effect on bacterial bioburden. The dressings selected included two dressings with antimicrobial properties (one containing silver and one containing PHMB), a cotton-based dressing enclosed in a perforated sleeve of poly(ethylene terephthalate), a carboxymethyl cellulose-based dressing, a fibre-free alginate dressing, and a 12-ply 100% cotton gauze. Using the colony-drip flow reactor (DFR) model, a meticillin-resistant Staphylococcus aureus (MRSA) or Pseudomonas aeruginosa biofilm was grown underneath a dressing sample. Biofilm growth was examined via plate counts, fluorescent microscopy and scanning electron microscopy.

RESULTS

The dressings containing antimicrobial agents had the greatest effect on bacterial load. In the MRSA experiments, both antimicrobial dressings produced lower bacteria counts than the other dressings (p<0.001), while in the P. aeruginosa experiments, only the silver-containing sample had fewer bacteria (p<0.0001). However, neither antimicrobial dressing was able to completely eradicate the bacteria when testing with either microorganism.

CONCLUSION

The results presented herein illustrate that bacteria can grow unchallenged within the dressing environment and that an antimicrobial dressing can limit this bacterial growth.

DECLARATION OF INTEREST

None.

Hyperbaric Oxygen in Tinnitus: Influence of Psychological Factors on Treatment Results?

INTRODUCTION

The standard treatment of subjective tinnitus hardly reaches the level of placebo controls. Though the effectiveness of hyperbaric oxygenation (HBO) for subjective tinnitus has never been objectified, it is still advocated by some institutions. We analyzed the effectiveness of hyperbaric oxygen treatment in the context of accompanying factors.

PATIENTS AND METHODS

We randomized 360 patients suffering from tinnitus into 2 HBO treatment protocols (group A: 2.2 bar for 60 min bottom time and group B: 2.5 bar for 60 min bottom time once a day for 15 days). All patients were asked to fill in a questionnaire (social and medical history, tinnitus characteristics, pre-HBO duration of tinnitus, prior therapy, pretreatment expectation, accompanying symptoms). A subjective assessment of the therapeutic effect was obtained.

RESULTS

Twelve patients (3.3%) experienced complete remission of tinnitus, in 122 (33.9) the intensity lessened, and 44 (12.2%) had a subjectively agreeable change of noise characteristics. No change was found in 157 cases (43.6%) and 25 (6.9%) experienced deterioration. There was no statistically significant difference between groups A and B (p > 0.05). Out of 68 patients with a positive expectation of HBO effects, 60.3% stated that the tinnitus had improved whereas only 47.2 and 19%, respectively, out of patients who underwent therapy with an indifferent (n = 271) or negative expectation (n = 21) reported an improvement. The influence of subjective expectation on the outcome was statistically significant (p < 0.05).

CONCLUSION

The therapeutic effects of HBO on subjective tinnitus may be substantially influenced by psychological mechanisms.

Hyperbaric oxygen (HBO2) in tinnitus: influence of psychological factors on treatment results?

HBO2 for subjective tinnitus has never been objectified, yet it is still advocated by many institutions. We analyzed the therapeutic effect of HBO2 treatment in the context of accompanying factors, especially focusing on the patients' attitude towards HBO2 prior to therapy.

METHODS

360 patients suffering from tinnitus were investigated in this study. They were randomized into 2 hyperbaric treatment protocols, one at 2.2, the other at 2.5 bar, 60 min bottom time each. All patients were asked to fill in a questionnaire (social and medical history, tinnitus characteristics, pre-HBO2 duration oftinnitus, prior therapy, pre-treatment expectation, accompanying symptoms) immediately before and one month after HBO2 treatment. The subjective impact of tinnitus on daily life was assessed using a score from 1 to 10 prior to HBO2 and one month after the treatment.

RESULTS

12 patients (3.3%) experienced complete remission of tinnitus, in 122 (33.9%) the intensity lessened, and 44 (12.2%) had a subjectively agreeable change of noise characteristics. 157 (43.6%) stated no change and 25 (6.9%) experienced deterioration. There was no statistically significant difference between the two hyperbaric protocols (p > 0.05). Out of 68 patients with positive expectation towards HBO2 therapy 60.3% stated that the tinnitus had improved whereas out of the patients who underwent therapy with indifferent (N = 271) or negative expectations (N = 21) only 47.2% and 19%, respectively, reported an improvement. The influence of both positive and negative anticipation on the outcome was statistically significant (p < 0.05).

CONCLUSION

The therapeutic effects of HBO2 on subjective tinnitus might be greatly due to psychological mechanisms triggered by the attitude of the patient towards HBO2 therapy prior to the treatment.

Scintimammography enhances negative predictive value of non-invasive pre-operative assessment of breast lesions

AIMS

The aim of this study was to develop a criterion with a high negative predictive value for the evaluation of breast lesions. We aimed to determine the value of combining three non-invasive tests, mammography (MM), ultrasonography (USS) and 99mTc-methoxyisobutylisonitrite (99mTc-MIBI) scintimammography (scinti-MM).

METHODS

We included 94 consecutive patients with suspected lesions detected by mammography or on physical examination. MM, USS and scinti-MM were performed no more than 4 weeks prior to excisional biopsy in all patients. We then compared the biopsy results with a score calculated for each patient, derived from the results of the three tests, which we termed 'mamma malignancy index' (MMI).

RESULTS

Each of the three exams yielded a score ranging from 0 to 2, with 0 representing an almost certainly benign lesion, 1 an indeterminate finding and 2 a likely malignant lesion, and hence giving a total score ranging from 0 to 6. The biopsy results showed that the lesions in 64 patients were benign. Forty-nine (77%) of these patients had received an MMI score of 0 or 1. The negative predictive value for malignancy in patients with a score less than 2 was 100%.

CONCLUSIONS

Since the smallest detected lesion was 9 mm in diameter, we conclude that MMI may be a highly useful diagnostic tool in the delineation of breast lesions > or =1 cm which should not be routinely referred for biopsy but may be followed non-invasively. Although fine needle aspiration has limitations, we would recommend it as a less invasive method to evaluate suspected lesions smaller than 1 cm.

From scattering singularities to the partition of a horseshoe

In a chaotic scattering system there are two different approaches to construct a symbolic dynamics. One comes from the branching tree obtained from a scattering function. The other comes from a Markov partition based on the line of primary homoclinic tangencies in the Poincare map taken in the interaction region. In general the two results only coincide for a complete horseshoe. We show how to make a different choice for the partition in the internal Poincare section based on scattering behavior and not on homoclinic tangencies. Then the corresponding symbolic dynamics coincides also for the incomplete case with the one obtained naturally from the scattering functions. The scattering based partition lines of the horseshoe are constructed by an iterative procedure. (c) 1999 American Institute of Physics.

Frequency of pulmonary embolism in patients who have iliofemoral deep vein thrombosis and are treated with once- or twice-daily low-molecular-weight heparin

PURPOSE

The purpose of this study was to compare the efficacy and safety of treating mobile iliofemoral patients with deep venous thrombosis (DVT) with subcutaneous low-molecular-weight heparin (dalteparin sodium) either 200 IU/kg once-daily (group 1) or 100 IU/kg twice-daily (group 2).

METHODS

Consecutive patients with suspected iliofemoral DVT diagnosed by duplex ultrasonography and verified by radionuclide venography were randomized to one of the two low-molecular-weight heparin (LMWH) regimens. Perfusion and when necessary ventilation scans were performed for diagnosis of pulmonary emboli (PE) in all patients immediately after admission and were repeated after approximately 10 days, whereupon oral anticoagulation was started unless contraindicated. Minimal and maximal anti-factor Xa activity was measured after 2 to 3 days of therapy. All patients were kept mobile with compression bandages. The primary end point was reduction in frequency of PE as assessed on the second lung scan.

RESULTS

A total of 140 patients with confirmed DVT were randomized, 76 to group 1 and 64 to group 2. The two groups were comparable in their baseline clinical characteristics. In the initial lung scans 36 (47.4%) patients in group 1 and 29 (45.3%) patients in group 2 had objectively verified PE, but only 11 (14.5%) and 8 (12.5%) patients, respectively, had symptoms. After dalteparin treatment PE disappeared in two patients in group 1, but in two other cases new PEs occurred, (NS). In group 2 a resolution of PEs was observed in eight patients, whereas only one new PE could be detected. This change reflects the efficacy of therapy as defined by resolution of existing PEs and by the occurrence of new PEs and is statistically significant according to McNemar's chi-square test with the exact binomial method pair procedure (p < 0.05). Symptomatic PE was reduced from 14.5% to 5.3% in group 1 (96% to CI for the difference, -1.5% to +17.3%) and from 12.5% to 1.6% in group 2 (95% CI for the difference 0.7% to 18%, p < 0.05). There was one single fatal PE, one serious and three minor bleeding episodes in group 1, and one minor bleeding episode in group 2 (95% CI for the difference: -3.6% to +8.1%).

CONCLUSIONS

Treatment of ambulant iliofemoral patients with DVT with 100 IU/kg dalteparin twice-daily appears to be moe safe and effective than 200 IU/kg given once-daily. Bed rest is not necessary for treating mobile patients.