Nanofibrillar cellulose wound dressing in skin graft donor site treatment.

BACKGROUND: Although new therapeutic approaches for burn treatment have made progress, there is still need for better methods to enhance wound healing and recovery especially in severely burned patients. Nanofibrillar cellulose (NFC) has gained attention due to its renewable nature, good biocompatibility and excellent physical properties that are of importance for a range of applications in pharmaceutical and biomedical fields. In the present study, we investigated the potential of a wood based NFC wound dressing in a clinical trial on burn patients. Previously, we have investigated NFC as a topical functionalized wound dressing that contributes to improve wound healing in mice. METHODS: Wood based NFC wound dressing was tested in split-thickness skin graft donor site treatment for nine burn patients in clinical trials at Helsinki Burn Centre. NFC dressing was applied to split thickness skin graft donor sites. The dressing gradually dehydrated and attached to donor site during the first days. During the clinical trials, physical and mechanical properties of NFC wound dressing were optimized by changing its composition. From patient 5 forward, NFC dressing was compared to commercial lactocapromer dressing, Suprathel® (PMI Polymedics, Germany). RESULTS: Epithelialization of the NFC dressing-covered donor site was faster in comparison to Suprathel®. Healthy epithelialized skin was revealed under the detached NFC dressing. NFC dressing self-detached after 11-21days for patients 1-9, while Suprathel® self-detached after 16-28days for patients 5-9. In comparison studies with patients 5-9, NFC dressing self-detached on average 4days earlier compared with Suprathel®. Lower NFC content in the material was evaluated to influence the enhanced pliability of the dressing and attachment to the wound bed. No allergic reaction or inflammatory response to NFC was observed. NFC dressing did not cause more pain for patients than the traditional methods to treat the skin graft donor sites. CONCLUSION: Based on the preliminary clinical data, NFC dressing seems to be promising for skin graft donor site treatment since it is biocompatible, attaches easily to wound bed, and remains in place until donor site has renewed. It also detaches from the epithelialized skin by itself.

Lithography-free oxide patterns as templates for self-catalyzed growth of highly uniform GaAs nanowires on Si(111).

We report self-catalyzed growth of GaAs nanowires (NWs) on Si/SiOx patterns fabricated by a lithography-free method. The patterns are defined using droplet epitaxy of GaAs nanocrystals, spontaneous oxidation, and thermal annealing. We investigate the influence of the size and density of the nucleation sites on the NW growth process and show that this approach enables the fabrication of highly uniform GaAs NWs with controllable density. The pattern fabrication and NW growth process are studied and discussed in relation to the surface morphology and chemical properties of the Si/SiOx patterns. Furthermore, the optical quality of the NWs is investigated by photoluminescence experiments performed for GaAs­AlGaAs core­shell NWs.

The impact of surgical wound bacterial colonization on the incidence of surgical site infection after lower limb vascular surgery: a prospective observational study.

OBJECTIVE: To study the relationship between surgical wound bacterial colonization and the development of surgical site infection (SSI) after lower limb vascular surgery. SSI is a major problem after lower limb vascular surgery. Most SSIs in vascular surgery are caused by Staphylococcal species that are part of normal skin flora. A prospective observational investigator blind study to examine quantitative and qualitative analysis of surgical wound bacterial colonization and the correlation with the development of SSI has been conducted. METHODS: The study cohort comprised 94 consecutive patients with 100 surgical procedures. Swabs for microbiological analyses were taken from surgical wounds at four different time intervals: before surgery, just before the surgical area had been scrubbed, at the end of surgery, and on the first and second postoperative days. Postoperative complications were recorded. RESULTS: Three hundred and eighty-seven skin bacterial samples from 100 surgical wounds were analyzed. The most common bacteria isolated were coagulase-negative staphylococci (80%), Corynebacterium species (25%), and Propionibacterium species (15%). In 13 (62%) cases, the same bacterial isolates were found in the perioperative study samples as in the infected wounds. The incidence of SSI was 21%. Multivariate analysis revealed that high bacterial load on the second postoperative day and diabetes independently increased the risk of SSI. Elective redo surgery was protective against the development of SSI. CONCLUSIONS: A high bacterial load in the postoperative surgical wound independently increases the risk of the development of SSI after lower limb vascular surgery.

Size-dependent properties of single InAs quantum dots grown in nanoimprint lithography patterned GaAs pits.

We report on the structural and optical properties of single InAs quantum dots (QDs) formed in etched GaAs pits with different dimensions. The site-controlled QDs were fabricated by molecular beam epitaxy on GaAs(001) surfaces patterned by nanoimprint lithography. We show that the properties of the QDs can be modified by varying the dimensions of the etched GaAs pits. Increasing the pit size resulted in larger QDs and thus in longer photoluminescence wavelengths. However, the fine structure splitting remained unaffected. A photoluminescence linewidth of 41 µeV and average fine structure splitting of 15.7 µeV were obtained for exciton recombination in the single site-controlled QDs.

Large array of single, site-controlled InAs quantum dots fabricated by UV-nanoimprint lithography and molecular beam epitaxy.

We present the growth of single, site-controlled InAs quantum dots on GaAs templates using UV-nanoimprint lithography and molecular beam epitaxy. A large quantum dot array with a period of 1.5 µm was achieved. Single quantum dots were studied by steady-state and time-resolved micro-photoluminescence experiments. We obtained single exciton emission with a linewidth of 45 µeV. In time-resolved experiments, we observed decay times of about 670 ps. Our results underline the potential of nanoimprint lithography and molecular beam epitaxy to create large-scale, single quantum dot arrays.

The influence of post-growth annealing on the optical properties of InAs quantum dot chains grown on pre-patterned GaAs(100).

We report on the effect of post-growth thermal annealing of [011]- ,[011(-)]-, and [010]-oriented quantum dot chains grown by molecular beam epitaxy on GaAs(100) substrates patterned by UV-nanoimprint lithography. We show that the quantum dot chains experience a blueshift of the photoluminescence energy, spectral narrowing, and a reduction of the intersubband energy separation during annealing. The photoluminescence blueshift is more rapid for the quantum dot chains than for self-assembled quantum dots that were used as a reference. Furthermore, we studied polarization resolved photoluminescence and observed that annealing reduces the intrinsic optical anisotropy of the quantum dot chains and the self-assembled quantum dots.

Structural characterization of InAs quantum dot chains grown by molecular beam epitaxy on nanoimprint lithography patterned GaAs(100).

We combine nanoimprint lithography and molecular beam epitaxy for the site-controlled growth of InAs quantum dot chains on GaAs(100) substrates. We study the influence of quantum dot growth temperature and regrowth buffer thickness on the formation of the quantum dot chains. In particular, we show that by carefully tuning the growth conditions we can achieve equal quantum dot densities and photoluminescence ground state peak wavelengths for quantum dot chains grown on patterns oriented along the [011], [01 ̄1], [011] and [001] directions. Furthermore, we identify the crystal facets that form the sidewalls of the grooves in the differently oriented patterns after capping and show that the existence of (411)A sidewalls causes reduction of the QD density as well as sidewall roughening.

Oncolytic adenovirus modified with somatostatin motifs for selective infection of neuroendocrine tumor cells.

We have previously described the oncolytic adenovirus, Ad(CgA-E1A-miR122), herein denoted Ad5(CgA-E1A-miR122) that selectively replicates in and kills neuroendocrine cells, including freshly isolated midgut carcinoid cells from liver metastases. Ad5(CgA-E1A-miR122) is based on human adenovirus serotype 5 (Ad5) and infects target cells by binding to the coxsackie-adenovirus receptor (CAR) and integrins on the cell surface. Some neuroendocrine tumor (NET) and neuroblastoma cells express low levels of CAR and are therefore poorly transduced by Ad5. However, they often express high levels of somatostatin receptors (SSTRs). Therefore, we introduced cyclic peptides, which contain four amino acids (FWKT) and mimic the binding site for SSTRs in the virus fiber knob. We show that FWKT-modified Ad5 binds to SSTR2 on NET cells and transduces midgut carcinoid cells from liver metastases about 3-4 times better than non-modified Ad5. Moreover, FWKT-modified Ad5 overcomes neutralization in an ex vivo human blood loop model to greater extent than Ad5, indicating that fiber knob modification may prolong the systemic circulation time. We conclude that modification of adenovirus with the FWKT motif may be beneficial for NET therapy.

Ad5/3-9HIF-Delta24-VEGFR-1-Ig, an infectivity enhanced, dual-targeted and antiangiogenic oncolytic adenovirus for kidney cancer treatment.

Despite good safety data in clinical trials, oncolytic adenoviruses have not been efficient enough to make them a viable treatment alternative for cancers. As more potent viruses are being made, transcriptional and transductional targeting to tumor tissues becomes increasingly appealing. To improve antitumor efficacy, oncolytic adenoviruses can be armed with therapeutic transgenes, such as the antiangiogenic soluble vascular endothelial growth factor receptor 1-Ig fusion protein. We hypothesized that an infectivity enhanced, targeted, vascular endothelial growth factor receptor 1-Ig armed oncolytic adenovirus would exhibit improved specificity and antitumor effect in murine kidney cancer models. Two hypoxia inducible factor-sensitive promoters were evaluated for renal cancer specificity using a novel in vivo dual luciferase-imaging system. Earlier data had shown usefulness of the 5/3-serotype chimera capsid modification for kidney cancer. Therefore, we constructed Ad5/3-9HIF-Delta24-VEGFR-1-Ig, which showed good specificity and oncolytic effect on renal cancer cells in vitro and resulted in antitumor efficacy in a subcutaneous in vivo model, in which vascular endothelial growth factor receptor 1-Ig expression and a concurrent antiangiogenic effect were confirmed. In an intraperitoneally disseminated kidney cancer model, significantly enhanced survival was observed when compared with control viruses. These results suggest that a targeted, antiangiogenic, oncolytic adenovirus might be a valuable agent for testing in kidney cancer patients.

Extended release of adenovirus from silica implants in vitro and in vivo.

Despite promising preclinical results, the clinical benefits of cancer gene therapy have been modest heretofore. The main obstacle continues to be the level and persistence of gene delivery to sufficiently large areas of the tumor. One approach for overcoming this might entail extended local virus release. We studied the utility of silica gel monoliths for delivery of adenovirus to advanced orthotopic gastric and pancreatic cancer tumors. Initially, the biochemical properties of the silica-virus matrix were studied and nearly linear release as a function of time was detected. Virus stayed infective for weeks at +37 degrees C and months at +4 degrees C, which may facilitate storage and distribution. In vivo, extended release of functional replication deficient and also replication-competent, capsid-modified oncolytic viruses was seen. Treatment of mice with pancreatic cancer doubled their survival (P<0.001). Also, silica gel-based delivery slowed the development of antiadenovirus antibodies.

Changing the adenovirus fiber for retaining gene delivery efficacy in the presence of neutralizing antibodies.

Prior infection has primed most adult humans for a rapid neutralizing antibody (NAb) response when re-exposed to adenovirus. NAb induction can severely limit the efficacy of systemic re-administration of adenoviral gene therapy. We hypothesized that changing the fiber knob could overcome NAb. Immune-competent mice were exposed to serotype 5 adenovirus (Ad5)(GL), Ad5/3luc1, Ad5lucRGD or Ad5pK7(GL). Mice immunized with Ad5(GL) featured reduced intravenous Ad5(GL) gene transfer to most organs, including the liver, lung and spleen. Ad5(GL) gene transfer was affected much less by exposure to capsid-modified viruses. Anti-Ad5(GL) NAb blocked intravenous Ad5(GL) gene transfer to orthotopic lung cancer xenografts, whereas capsid-modified viruses were not affected. When gene transfer to fresh cancer and normal lung explants was analyzed, we found that capsid-modified viruses allowed effective gene delivery to tumors in the presence of anti-Ad5(GL) NAb, whereas Ad5(GL) was blocked. In contrast, crossblocking by NAbs induced by different viruses affected gene delivery to normal human lung explants, suggesting the importance of non-fiber-knob-mediated infection mechanisms. We conclude that changing the adenovirus fiber knob is sufficient to allow a relative degree of escape from preexisting NAb. If confirmed in trials, this approach might improve the efficacy of re-administration of adenoviral gene therapy to humans.

Transformation of InAs islands to quantum ring structures by metalorganic vapor phase epitaxy.

The transformation of InAs islands to quantum rings (QRs) by metalorganic vapor phase epitaxy is investigated. After covering the InAs islands with a thin GaAs partial capping layer and annealing under tertiarybutylarsine (TBAs) flow, ring-shaped nanostructures with a density of 10(7)-10(9) cm(-2) are obtained at 500-600 °C. The effects of the growth temperature, annealing process and thickness of the partial capping layer are studied. Optimum values for the annealing time and the partial capping layer thickness were found to be 60-120 s and 0.5-2.0 nm, respectively. Low temperature photoluminescence (PL) emission peaks from islands and QRs grown at 500 °C are observed at 1.04 eV and 1.22 eV, respectively. The annealing temperature affected the QR evolution and the PL emission from the QRs due to the temperature dependence of the diffusion rate of indium atoms.

Utility of TK/GCV in the context of highly effective oncolysis mediated by a serotype 3 receptor targeted oncolytic adenovirus.

Arming oncolytic adenoviruses with therapeutic transgenes and enhancing transduction of tumor cells are useful strategies for eradication of advanced tumor masses. Herpes simplex virus thymidine kinase (TK) together with ganciclovir (GCV) has been promising when coupled with viruses featuring low oncolytic potential, but their utility is unknown in the context of highly effective infectivity-enhanced viruses. We constructed Ad5/3-Delta24-TK-GFP, a serotype 3 receptor-targeted, Rb/p16 pathway-selective oncolytic adenovirus, where a fusion gene encoding TK and green fluorescent protein (GFP) was inserted into 6.7K/gp19K-deleted E3 region. Ad5/3-Delta24-TK-GFP killed ovarian cancer cells effectively, which correlated with GFP expression. Delivery of GCV immediately after infection abrogated viral replication, which might have utility as a safety switch. Due to the bystander effect, killing of some cell lines in vitro was enhanced by GCV regardless of timing. In murine models of metastatic ovarian cancer, Ad5/3-Delta24-TK-GFP improved antitumor efficacy over the respective replication-deficient virus with GCV. However, GCV did not further enhance efficacy of Ad5/3-Delta24-TK-GFP in vivo. Simultaneous detection of tumor load and virus replication with bioluminescence and fluorescence imaging provided insight into the in vivo kinetics of oncolysis. In summary, TK/GCV may not add antitumor activity in the context of highly potent oncolysis.

Luciferase imaging for evaluation of oncolytic adenovirus replication in vivo.

Oncolytic viruses kill cancer cells by tumor-selective replication. Clinical data have established the safety of the approach but also the need of improvements in potency. Efficacy of oncolysis is linked to effective infection of target cells and subsequent productive replication. Other variables include intratumoral barriers, access to target cells, uptake by non-target organs and immune response. Each of these aspects relates to the location and degree of virus replication. Unfortunately, detection of in vivo replication has been difficult, labor intensive and costly and therefore not much studied. We hypothesized that by coinfection of a luciferase expressing E1-deleted virus with an oncolytic virus, both viruses would replicate when present in the same cell. Photon emission due to conversion of D-Luciferin is sensitive and penetrates tissues well. Importantly, killing of animals is not required and each animal can be imaged repeatedly. Two different murine xenograft models were used and intratumoral coinjections of luciferase encoding virus were performed with eight different oncolytic adenoviruses. In both models, we found significant correlation between photon emission and infectious virus production. This suggests that the system can be used for non-invasive quantitation of the amplitude, persistence and dynamics of oncolytic virus replication in vivo, which could be helpful for the development of more effective and safe agents.

A heparan sulfate-targeted conditionally replicative adenovirus, Ad5.pk7-Delta24, for the treatment of advanced breast cancer.

Conditionally replicating adenoviruses (CRAds) that replicate in tumor but less in normal cells are promising anticancer agents. A major determinant of their potency is their capacity for infecting target cells. The primary receptor for serotype 5 adenovirus (Ad5), the most widely used serotype in gene therapy, is the coxsackie-adenovirus receptor (CAR). CAR is expressed variably and often at low levels in various tumor types including advanced breast cancer. We generated a novel p16/retinoblastoma pathway-dependent CRAd, Ad5.pK7-Delta24, with a polylysine motif in the fiber C-terminus, enabling CAR-independent binding to heparan sulfate proteoglycans (HSPG). Ad5.pK7-Delta24 mediated effective oncolysis of all breast cancer cell lines tested. Further, we utilized noninvasive, fluorescent imaging for analysis of antitumor efficacy in an orthotopic model of advanced hormone refractory breast cancer. A therapeutic benefit was seen following both intratumoral and intravenous delivery. Murine biodistribution similar to Ad5, proven safe in trials, suggests feasibility of clinical safety testing. Interestingly, upregulation of CAR was seen in low-CAR M4A4-LM3 breast cancer cells in vivo, which resulted in better than expected efficacy also with an isogenic CRAd with an unmodified capsid. These results suggest utility of Ad5.pK7-Delta24 and the orthotopic model for further translational studies.

Crystal-structure-dependent photoluminescence from InP nanowires.

The formation and photoluminescence (PL) of InP nanowires grown by metal organic vapour phase epitaxy on InP(111)B substrates, using colloidal gold nanoparticles as catalysts, are investigated. The dependence of the orientation and dimensions of the nanowires on the growth temperature is studied using scanning electron microscopy. Vertically aligned [Formula: see text] oriented nanowires with a mean base diameter in the range 50-150 nm, and a tip diameter of 50 nm, show a PL blue-shift of about 80 meV compared to the substrate. Blue-shift due to quantum confinement is ruled out because of the large diameter of the nanowires. A clear correlation between the orientation of the nanowires on the substrate and the PL peak position is observed. Based on x-ray diffraction and transmission electron microscopy measurements, it is proposed that the as-grown vertically oriented nanowires have crystallized in the wurtzite lattice instead of in the zinc-blende structure, which results in a blue-shifted PL.

Noninvasive dual modality in vivo monitoring of the persistence and potency of a tumor targeted conditionally replicating adenovirus.

In clinical trials with cancer patients, the safety of conditionally replicating adenoviruses (CRAds) has been good. However, marginal data are available on the persistence or antitumor efficacy of these agents. The oncolytic potency of CRAds is determined by their capacity for entering target cells. Consequently, we constructed a retargeted CRAd featuring a secreted marker protein, soluble human carcinoembryogenic antigen (hCEA), which can be measured in growth medium or plasma. We found that virus replication closely correlated with hCEA secretion both in vitro and in vivo. Further, antitumor efficacy and the persistence of the virus could be deduced from plasma hCEA levels. Finally, using in vivo bioluminescence imaging, we were able to detect effective tumor cell killing by the virus, which led to enhanced therapeutic efficacy.

Green fluorescent protein (GFP) fusion constructs in gene therapy research.

The history of green fluorescent protein (GFP) as a marker is less than 10 years old, but it has already made a major impact on many areas of natural sciences, especially on cell biology and histochemistry. GFP can be detected in living cells without selection or staining and it can be fused to other proteins to yield fluorescent chimeras. The potential of GFP has also been recognised by gene therapy researchers and various GFP-tagged therapeutic proteins have been constructed. These chimeric proteins have been used to determine the expression level, site and time course of the therapeutic gene, or the correlation between gene transfer rate and therapeutic outcome. This review summarises the status of the applications of GFP fusions in gene therapy research.

Auditing a nationwide vascular registry--the 4-year Finnvasc experience. Finnvasc Study Group.

OBJECTIVE: To assess the validity of a national vascular registry. MATERIALS AND METHODS: 17,465 vascular and endovascular procedures, immediate reoperations excluded, registered in the Finnvasc registry from 26 centres during the years 1991-1994. CHIEF OUTCOME MEASURES: Comparison of the number of registered procedures with hospital records, comparison of initial registrations with a random sample of re-registration and comparison of the 1-year local data input of one major centre to the same data input of the central unit. RESULTS: The rate of missing registrations was 19% ranging from 0-47%. The data of the re-registered forms were in agreement with the original data in 93% of all data points, the range being from 81-100%. There was a difference of 1.5% in the data between the major centre and the central unit. CONCLUSIONS: The Finnvasc registry makes it possible to audit vascular surgery nationally, although a potential limitation is centres with low registration rates.