[Tibiotalocalcaneal Arthrodesis: Comparison of Fixation Methods, Mid-Term Clinical Results]

PURPOSE OF THE STUDY The authors focused on the topic of tibiotalocalcaneal arthrodesis. It is a surgical procedure used to manage severe comprehensive ankle and hindfoot pathology. The scope of surgery and the negative impact on the walking stereotype are offset by preserving a weight-bearing and pain-free limb. The purpose of the study was to evaluate the group of patients who had undergone surgery at the First Department of Orthopaedic Surgery, St. Anne s University Hospital Brno and to identify the most suitable fixation for arthrodesis. It also aimed to compare the outcomes achieved by the authors with those reported by other departments. MATERIAL AND METHODS The group included patients operated on at the authors department between 2011 and 2021. The surgery was indicated in patients with severe concomitant arthritis of the upper and lower ankle, complex hindfoot instability, Charcot arthropathy. Contraindications included acute infection, decompensated diabetes and heavy smoking. The study compares fixation using a lateral plate, a retrograde nail and a retrograde nail with fibula acting as biological plate. The patients were scored preoperatively and postoperatively using the AOFAS Ankle-Hindfoot Score. Statistical analysis of the results was also carried out. RESULTS The group included 23 patients, of whom a lateral plate was opted for in 7 patients, a retrograde nail in 8 patients and a retrograde nail with fibula used as a biological plate in 8 patients. The patients of the group were followed up for the period ranging from 0.5 to 9 years after surgery. Serious complications were observed by the authors in 6 patients of the group. The failure of osteosynthesis material was reported in 2 cases with lateral plating fixation. A stress fracture above the apex of the nail developed in 2 cases. A serious infection was observed by the authors in 1 patient. The method associated with the lowest incidence of complications was the fixation with a retrograde nail and fibula used as a biological plate. DISCUSSION The forms of fixation for tibiotalocalcaneal arthrodesis have recently advanced considerably, the methods of fixation for arthrodesis in particular. The modern implants enable to compress the individual structures, to provide stable fixation and potentially to avoid long-term plaster cast fixation. Nonetheless, these surgical procedures are associated with a high complication rate. Currently, there is no consensus in international studies on the optimal fixation for arthrodesis. Numerous papers describe complications including postoperative infections, failure of osteosynthesis material and fractures close to osteosynthesis material. The number and the type of complications observed by the authors in their group of patients were similar to those reported by other authors. CONCLUSIONS Tibiotalocalcaneal arthrodesis is a surgical procedure reserved exclusively for patients indicated based on strict criteria and should be performed by an experienced team able to cope with potential complications. In the followed-up group of patients, the optimal method of fixation for arthrodesis appeared to be the fixation with a retrograde nail and fibula used as a biological plate. Key words: tibiotalocalcaneal arthrodesis, retrograde nail, lateral ankle plate, ankle instability, ankle arthrosis, biological plate.

[Intramedullary Nailing in Managing Diaphyseal Metastases of Long Bones: Retrospective Study Comparing the Expected Survival and the Actual Survival of Patients]

PURPOSE OF THE STUDY The paper focuses on the potential use of nail osteosynthesis in diaphyseal metastases of long bones. The purpose of the paper is to assess the outcomes of intramedullary osteosynthesis in pathologic and impending pathologic fractures, to evaluate patient survival and potential complications. MATERIAL AND METHODS The retrospective study evaluated a cohort of 42 patients (19 men and 23 women) in whom intramedullary osteosynthesis was performed for complete pathologic fracture (28 patients) or impending pathologic fracture (14 patients) between 2010 and 2019. Of the total number of 42 patients, 31 patients' lower limbs were affected, namely by 17 pathologic fractures and 14 impending fractures. There were 11 humerus fractures. The mean age was 61.8 years (range 41-84 years). In the followed-up cohort, the patient survival after osteosynthesis with intramedullary nails, complications occurred and post-operative mobility of the patient were assessed. The functional outcomes were evaluated using the Musculoskeletal Tumor Society (MSTS) scoring system. The unpaired Mann-Whitney test was used to test the significance of the difference in functional outcomes and survival between the followed-up groups. Survival longer than 6 months was evaluated using Fisher's exact test. The level of statistical significance used for the test was p 0.05. RESULTS The investigated indicator was patient survival, which was 11.3 months (range 1-50 months) on average. In the group of impending fractures, the mean survival was 13.5 months. In the group of pathologic fractures, the survival was 10 months. The functional outcome in 16 followed-up patients at three months after intramedullary osteosynthesis according to the MSTS score was 46.9% (30-66.7%). At the level of significance of p 0.05, the statistically significant difference in the functional outcomes between the group with preventive intramedullary osteosynthesis and the group with nail osteosynthesis of the pathologic fracture was not confirmed (p=0.952). When comparing the patient survival after nail osteosynthesis with impending pathologic fracture and the survival of patients with pathologic fracture, a statistically significant difference in survival between these two groups (p=0.520) was not confirmed. The patient survival of longer than 6 months was 71% in the group of impending fractures and 40% in the group of pathologic fractures. DISCUSSION The occurrence of pathologic fracture is associated with increased pain, loss of function, and according to some authors, a higher risk of death. Surgical treatment options include intramedullary osteosynthesis, plate osteosynthesis with cement filling, implantation of an intercalary spacer, and implantation of tumor endoprostheses. When deciding on a surgical procedure, an account is taken of the expected survival of the patient. In patients with an expected survival of up to 6 months, intramedullary osteosynthesis is indicated as a palliative surgical intervention. The most common complications include implant failure and metastatic progression. CONCLUSIONS Intramedullary osteosynthesis is the method of choice in treating pathologic fractures or impending pathologic diaphyseal fractures of long bones in patients with an expected predicted survival of up to 6 months. Intramedullary osteosynthesis aims to reduce pain and enable early verticalization. The study confirmed the importance of preventive intramedullary osteosynthesis and its effect on survival compared to the survival of patients with a pathologic fracture. Key words: skeletal metastases, diaphyseal metastases, intramedullary osteosynthesis, pathologic fracture, impending fracture.

P14.24 Estimating survival outcomes in elderly (70+ years) patients with primary glioblastoma

BACKGROUND

Elderly patients with glioblastoma are perceived to face a poor prognosis, with perceptions around older age and a relative lack of randomized data raising a concern about their undertreatment. The EANO guidelines recommend >70-year-old patients with good performance status to undergo maximal safe resection followed by hypofractionated (40 Gy in 15 fractions, i.e. RT40/15) radiotherapy with or without concurrent and adjuvant Temozolomide (TMZ), depending on MGMT promoter methylation. This study evaluated the relative survival impact of biological, histological, surgical and oncological factors and aimed to devise a scoring system to estimate the survival of elderly glioblastoma patients, with an aim to more accurately guide treatment in this cohort.

METHODS

The records of 169 elderly (≥70 years) patients with a new diagnosis of IDH-wild type glioblastoma were retrospectively examined for gender, age, WHO performance status (PS), comorbidities, MGMT methylation, surgical intervention and chemoradiation regime. The adjusted survival impact of these factors was determined using Cox proportional hazards model and used to devise a two-stage scoring system to estimate survival of patients at the stage of surgical (Elderly Glioblastoma Surgical Score, EGSS) and oncological management (Elderly Glioblastoma Oncological Score, EGOS).

RESULTS

The overall median survival (MS) of the cohort was 28.8 weeks. Subtotal resection (MS=27.7 weeks, 95%CI 24.1–31.6 weeks, HR=0.58) and gross-total resection (MS=77.8 weeks, 95%CI 67.0–88.6 weeks, HR=0.36) were associated with significant overall survival benefit compared to biopsy alone (MS=18.2 weeks, 95%CI 15.7–20.7 weeks, HR=5.23), p<0.05. Hypofractionated radiation with Temozolomide (RT40/15+TMZ, MS=60.9 weeks, 95%CI 49.9–71.8 weeks, HR=0.13) was non-inferior to the Stupp protocol (RT60/30+TMZ, MS=50.6 weeks, 95%CI 32.4–66.7 weeks, HR=0.11), p=0.72. Negative prognosticators included age above 75 years, biopsy alone and no chemoradiotherapy. Subgroup analysis revealed that MGMT unmethylated 70–75 year old patients who received the Stupp protocol had significantly improved overall survival (MS=57.6 weeks, 95%CI 27.7–88.1 weeks) compared to standard of care RT40/15 alone (MS=29.7 weeks, 95%CI 7.1–51.6 weeks), p=0.002. EGSS and EGOS scores estimated survival with 65% and 73% accuracy, respectively.

CONCLUSION

When appropriate and safe, a subgroup of elderly glioblastoma patients may benefit from more aggressive surgical and oncological management. The proposed EGSS and EGOS scores takes into account important prognostic factors to help guide which patients should receive such treatment.

[Long-Term Results of Total Knee Replacement Using P.F.C. Sigma System with an All-Polyethylene Tibial Component]

PURPOSE OF THE STUDY Use of an all-polyethylene (all-poly, AP) tibial component in primary total knee arthroplasty is still an attractive option considering the durability of replacement, the elimination of backside wear and the lower cost compared to modular metalbacked tibia. The purpose of the study was to evaluate the long-term results of the total knee replacement using the P.F.C. Sigma system with a monoblock all-polyethylene tibial component implanted at the 1st Orthopedic Department of the St. Anne's University Hospital and Masaryk University Brno in the period 1999-2010. MATERIAL AND METHODS In the monitored period, 911 total knee replacements using P.F.C. Sigma with an all-polyethylene tibial component were performed. This cohort of patients was evaluated at least 10 years after the primary replacement surgery. Altogether 323 knee replacements in 289 patients were evaluated. The clinical outcomes were assessed according to the Knee Society Clinical Rating System (KSS) and the Total Knee Arthroplasty Roentgenographic Evaluation and Scoring System. The replacement survival was evaluated using the Kaplan-Meier survival analysis. RESULTS In the evaluated group, the average KS was 82.6 points and the average functional score was 74.7 points. Excellent results were recorded in 213 cases, good results in 78 and satisfactory in 23 replacements. Poor clinical results were reported in 9 patients. The average range of motion was 105.8°. In 5 knees (1.5%) revision surgery was performed for infection complications, 3 cases were complicated due to periprosthetic fractures, 4 replacements were revised due to anterior knee pain and 8 knees showed a limited range of motion. Only 1 replacement was revised for aseptic loosening, with no need for reimplantation of the component. The survivorship of the implant was 98.5 % at the follow-up of 12.8 years, including the reasons of reimplantation. DISCUSSION Total knee replacement with an all-polyethylene tibial component is not so popular as the metal-backed modular implants. The all-polyethylene tibial component has certain advantages: lower unit costs, no backside wear, no liner dislocation, possibility of conservative bone resection. On the other hand, this type of implant is not modular and augmentations or longer stems cannot be used. Even though this type of endoprosthesis is recommended exclusively for elderly patients with a lower level of activity, the current mid- and long-term results show that indications for all-poly implants are much broader. CONCLUSIONS The total knee replacement with an all-polyethylene tibial component shows very good long-term clinical outcomes with an excellent survival rate. The all-poly design is cost-effective and may be used not only in elderly patients. Key words: total knee replacement, all-polyethylene tibial component, long-term results.

Targeting eotaxin-1 and CCR3 receptor alleviates enteric neuropathy and colonic dysfunction in TNBS-induced colitis in guinea pigs

BACKGROUND

The accumulation of eosinophils is mediated by the chemokine receptor-3 (CCR3)-eotaxin axis. Increased expression of eotaxin and its receptor is associated with inflammatory bowel disease (IBD). Activation of eosinophils causes the release of cationic proteins that are neurotoxic such as eosinophil-derived neurotoxin (EDN). Damage to enteric neurons alters neurally controlled functions of the gut correlated with intestinal inflammation. We hypothesized that inhibition of the CCR3-eotaxin axis will prevent inflammation-induced functional changes to the gastrointestinal tract.

METHODS

Hartley guinea pigs were administered with trinitrobenzene sulfonate (TNBS; 30 mg/kg in 30% ethanol) intrarectally to induce colitis. A CCR3 receptor antagonist (SB 328437 [SB3]) was injected intraperitoneally 1 hour postinduction of colitis. Animals were euthanized 7 days post-treatment and colon tissues were collected for ex vivo studies. The EDN-positive eosinophils in the colon, indicating eosinophil activation, were quantified by immunohistochemistry. Effects of SB3 treatment on gross morphological damage, enteric neuropathy, and colonic dysmotility were determined by histology, immunohistochemistry, and organ bath experiments.

KEY RESULTS

The number of EDN-positive eosinophils was significantly increased in the lamina propria in close proximity to myenteric ganglia in inflamed colon. The TNBS-induced inflammation caused significant damage to colonic architecture and inhibition of colonic motility. Treatment with SB3 antagonist attenuated inflammation-associated morphological damage in the colon, reduced infiltration of EDN-positive eosinophils and restored colonic motility to levels comparable to control and sham-treated guinea pigs.

CONCLUSION & INFERENCES

This is the first study demonstrating that inhibition of CCR3-eotaxin axis alleviates enteric neuropathy and restores functional changes in the gut associated with TNBS-induced colitis.

3D-printed polymer antiresonant waveguides for short-reach terahertz applications

In this work, we present a 3D-printed waveguide that provides effective electromagnetic guidance in the THz regime. The waveguide is printed using low-cost polycarbonate and a conventional fused deposition modeling printer. Light guidance in the hollow core is achieved through antiresonance, and it improves the energy effectively transported to the receiver compared to free space propagation. Our demonstration adds to the field of 3D-printed terahertz components, providing a low-cost way of guiding terahertz radiation.

Waveguide lasers in ytterbium-doped tantalum pentoxide on silicon

A waveguide laser in an ytterbium-doped tantalum pentoxide film is reported. The waveguide is formed of a rib of sputtered tantalum pentoxide on top of oxidized silicon with an over-cladding of silica. Emission at a wavelength of 1025 nm was achieved with an absorbed pump power threshold and slope efficiency of ≈29  mW and 27%, respectively, for a cavity formed by a high reflector mirror and an estimated 12% Fresnel reflection from the bare end-face at the output.

A metamolecule antenna for coplanar waveguides

We report on a metamolecule antenna, based on a fish-scale design but augmented with two split-ring resonators (SRRs) placed within the fish-scale loops. The properties of the antenna resonator, with and without additional SRRs, were examined using finite element method simulations (COMSOL Multiphysics). The simulation findings were subsequently confirmed experimentally, using a vector network analyser coupled to an antenna-loaded coplanar waveguide (CPW). The addition of SRRs to the fish-scale meta-molecule leads to a demonstrably large increase in microwave-absorption. It is shown that the fish-scale/SRR/CPW combination performs as a microwave antenna. Simulations of the antenna gain and far-field emission are presented and discussed.

Maca reduces blood pressure and depression, in a pilot study in postmenopausal women

OBJECTIVE

Lepidium meyenii (Maca) has been used for centuries for its fertility-enhancing and aphrodisiac properties. In an Australian study, Maca improved anxiety and depressive scores. The effects of Maca on hormones, lipids, glucose, serum cytokines, blood pressure, menopausal symptoms and general well-being in Chinese postmenopausal women were evaluated.

METHODS

A randomized, double-blind, placebo-controlled, cross-over study was conducted in 29 postmenopausal Hong Kong Chinese women. They received 3.3 g/day of Maca or placebo for 6 weeks each, in either order, over 12 weeks. At baseline, week 6 and week 12, estradiol, follicle stimulating hormone (FSH), sex hormone binding globulin (SHBG), thyroid stimulating hormone (TSH), full lipid profiles, glucose and serum cytokines were measured. The Greene Climacteric, SF-36 Version 2, Women's Health Questionnaire and Utian Quality of Life Scales were used to assess the severity of menopausal symptoms and health-related quality of life.

RESULTS

There were no differences in estradiol, FSH, TSH, SHBG, glucose, lipid profiles and serum cytokines amongst those who received Maca as compared to the placebo group; however, significant decreases in diastolic blood pressure and depression were apparent after Maca treatment.

CONCLUSIONS

Maca did not exert hormonal or immune biological action in the small cohort of patients studied; however, it appeared to reduce symptoms of depression and improve diastolic blood pressure in Chinese postmenopausal women. Although results are comparable to previous similar published studies in postmenopausal women, there might be a cultural difference among the Chinese postmenopausal women in terms of symptom reporting.

Fluence and polarisation dependence of GaAs based Lateral Photo-Dember terahertz emitters

We characterise THz output of lateral photo-Dember (LPD) emitters based on semi-insulating (SI), unannealed and annealed low temperature grown (LTG) GaAs. Saturation of THz pulse power with optical fluence is observed, with unannealed LTG GaAs showing highest saturation fluence at 1.1 ± 0.1 mJ cm(-2). SI-GaAs LPD emitters show a flip in signal polarity with optical fluence that is attributed to THz emission from the metal-semiconductor contact. Variation in optical polarisation affects THz pulse power that is attributed to a local optical excitation near the metal contact.

Myeloid derived suppressor cells and their role in diseases

Myeloid derived suppressor cells (MDSCs) are a heterogeneous population of myeloid progenitors that can play a major role in tumour development and chronic inflammation. The importance of the suppressive function ofMDSCs was first suggested by studies involving cancer patients and cancer-bearing mice. In addition, recent studies have demonstrated that MDSCs can also be involved in many other pathological conditions. MDSCs have unique ways of abrogatingan immune response in addition to those utilised by other immune-suppressive cell types, for example via the induction of arginase-1 and consequent upregulation in reactive oxygen species (ROS) production. Due to their heterogeneity,they further can express a variety of lineage markers, which overlap with other myeloid cell types such as Gr1,CD11b, MHCIIlo, Ly6C and Ly6G, making it difficult to identify them by surface phenotype alone. The disparity between mouse and human MDSCs further complicates the identification of these elusive cell populations. In this review, we will summarise the recent updates on the methods for eliciting and studying different MDSC subsets, including newly proposed surface phenotypes, as well as insights into how their function is being characterised in both mice and humans. In addition, exciting new discoveries suggesting their involvement across a number of different pathological settings, such as sepsis, autoimmunity and Leishmaniasis, will be discussed.

Investigation of the role of the lateral photo-Dember effect in the generation of terahertz radiation using a metallic mask on a semiconductor

Pulses of coherent terahertz radiation can be efficiently generated by a lateral diffusion current after ultrafast generation of photo-carriers near a metal interface on the surface of a semiconductor, this is known as the lateral photo-Dember effect. We investigate how the emission depends on the pump spot position, size, power and how it is affected by the application of an applied external bias. We study the role of the metallic mask and how it suppresses emission from the carriers diffusing under it due to a reduction of available radiation states both theoretically and experimentally.

Inflammatory mediators hold the key to dendritic cell suppression and tumor progression

Cancer has long been considered a disease that is associated with immune tolerance. Its connection with inflammation initially appears paradoxical. During the last decade, it has become increasingly clear that immune infiltrates form an integral part of tumor and critically contribute to its development and progression. In the tumor milieu, a variety of inflammatory mediators, such as cytokines (IL- 6, IL-10, VEGF, TGFβ, M-CSF and GM-CSF), chemokines (CCL20 and CXCL8), hormones (prostanoids like PGE2), reactive oxygen species and cellular constituents (gangliosides), are continuously produced. These mediators represent a critical interface between immune and neoplastic compartments. Not only do they continuously support tumor survival and expansion, but suppress the function of immune cells, notably, dendritic cells - the powerful antigen presenting cells that are crucial for induction of tumor-specific immune responses. This review summarizes such a dual role of inflammatory factors and discusses the controversies associated with specific mediators including IL-10, GM-CSF and ROS in tumor and immune modulation. Identifying the inflammatory signature of cancer patients hence represents a critical task for individualized immunotherapy in the future.

Terahertz emission by diffusion of carriers and metal-mask dipole inhibition of radiation

Terahertz (THz) radiation can be generated by ultrafast photo-excitation of carriers in a semiconductor partly masked by a gold surface. A simulation of the effect taking into account the diffusion of carriers and the electric field shows that the total net current is approximately zero and cannot account for the THz radiation. Finite element modelling and analytic calculations indicate that the THz emission arises because the metal inhibits the radiation from part of the dipole population, thus creating an asymmetry and therefore a net current. Experimental investigations confirm the simulations and show that metal-mask dipole inhibition can be used to create THz emitters.

Cytokine profile and induction of T helper type 17 and regulatory T cells by human peripheral mononuclear cells after microbial exposure

The immunomodulatory effects of probiotics were assessed following exposure of normal peripheral blood mononuclear cells (PBMC), cord blood cells and the spleen-derived monocyte/macrophage cell line CRL-9850 to Lactobacillus acidophilus LAVRI-A1, Lb. rhamnosus GG, exopolysaccharides (EPS)-producing Streptococcus thermophilus St1275, Bifidobacteriun longum BL536, B. lactis B94 and Escherichia coli TG1 strains. The production of a panel of pro- and anti-inflammatory cytokines by PBMC following bacterial stimulation was measured, using live, heat-killed or mock gastrointestinal tract (GIT)-exposed bacteria, and results show that (i) all bacterial strains investigated induced significant secretion of pro- and anti-inflammatory cytokines from PBMC-derived monocytes/macrophages; and (ii) cytokine levels increased relative to the expansion of bacterial cell numbers over time for cells exposed to live cultures. Bifidobacteria and S. thermophilus stimulated significant concentrations of transforming growth factor (TGF)-β, an interleukin necessary for the differentiation of regulatory T cells (T(reg) )/T helper type 17 (Th17) cells and, as such, the study further examined the induction of Th17 and T(reg) cells after PBMC exposure to selected bacteria for 96 h. Data show a significant increase in the numbers of both cell types in the exposed populations, measured by cell surface marker expression and by cytokine production. Probiotics have been shown to induce cytokines from a range of immune cells following ingestion of these organisms. These studies suggest that probiotics' interaction with immune-competent cells produces a cytokine milieu, exerting immunomodulatory effects on local effector cells, as well as potently inducing differentiation of Th17 and T(reg) cells.

Numerical simulation of optical Stark effect saturable absorbers in mode-locked femtosecond VECSELs using a modified two-level atom model

The interaction of an optical pulse with a quantum well saturable absorber is simulated using a semi-classical two-level-atom model which has been modified to approximate spectral hole burning in the carrier distribution. Saturable absorption behaviour is examined in the limit where pulse duration approaches the carrier-carrier scattering time. For long pulses bleaching dominates the absorber response but as the pulse duration approaches the carrier-carrier scattering timescale an additional pulse shaping mechanism becomes active, allowing the absorber to continue to shorten pulses beyond the limit set by bleaching. Examination of the spectral and temporal absorption profiles suggests that intense pulses experience additional pulse shortening from the optical Stark effect.

Waveguide mode filters fabricated using laser-induced forward transfer

Titanium (Ti)-in-diffused lithium niobate waveguide mode filters fabricated using laser-induced forward transfer followed by thermal diffusion are presented. The mode control was achieved by adjusting the separation between adjacent Ti segments thus varying the average value of the refractive index along the length of the in-diffused channel waveguides. The fabrication details, loss measurements and near-field optical characterization of the mode filters are presented. Modeling results regarding the device performance are also discussed.

Gain bandwidth characterization of surface-emitting quantum well laser gain structures for femtosecond operation

We present a method to experimentally characterize the gain filter and calculate a corresponding parabolic gain bandwidth of lasers that are described by "class A" dynamics by solving the master equation of spectral condensation for Gaussian spectra. We experimentally determine the gain filter, with an equivalent parabolic gain bandwidth of up to 51 nm, for broad-band InGaAs/GaAs quantum well gain surface-emitting semiconductor laser structures capable of producing pulses down to 60 fs width when mode-locked with an optical Stark saturable absorber mirror.

Haemangioblastoma: a rare cause of a cerebellar mass in the elderly

In the elderly, cerebellar lesions are commonly metastatic tumours with poor prognosis. We describe two octogenarians who presented with obstructive hydrocephalus, secondary to posterior fossa tumours that, on computed tomography, were thought to be cerebellar metastases. Both lesions were excised and the histology proved them to be cerebellar haemangioblastomas, primary benign tumours of the posterior fossa, which are rare in the elderly.

Design of Peptide-Based Vaccines for Cancer

The immune system responds efficiently to bacteria, viruses and other agents however, the immune response to cancers is not as effective. In most cases other than specific genetic rearrangements leading to non-self proteins such as in leukemia and idiotypes in lymphoma, tumor associated proteins are self proteins and are not recognized by the immune system to prevent malignancy. In most cancers, patients develop antibodies and/or CTL-precursors to tumor associated antigens but are not effective in generating a therapeutic immune response. Adjuvants have been used with either whole tumors, subunits or peptides with the aim of increasing their immunity. Whole tumor antigens have certain advantages associated with it, such as ready availability as recombinant proteins, potential epitopes that can be presented by a number of MHC class I/II alleles and antibody development. The methods of identification of CD8 and CD4 epitopes either by use of epitope prediction algorithms or use of transgenic mice has made the use of defined synthetic peptides more attractive. The possibility to synthesize long peptides and introduce multiple epitopes (CD4 or CD8) from single or multiple antigens makes peptide a viable alternative to whole proteins. As an alternative to totally synthetic peptide constructs or polymers, polytopes have been generated by genetic engineering methods. In addition, to deliver immunogens to and to activate DC, receptor-mediated delivery of peptides using antibodies, cytokines and carbohydrates have been used. This review will encompass the various strategies, preclinical and clinical applications in designing peptide-based vaccines for cancer.

Alveolar macrophage function is altered in patients with lung cancer

The alveolar macrophage (AM) is believed to be of central importance in the immune response against infection and tumour. We examined patients with lung cancer in order to evaluate the immuno-stimulatory potential of AM in lung cancer. Bronchoalveolar lavage fluid samples were obtained from patients with adenocarcinoma, squamous cell carcinoma, large cell undifferentiated lung carcinoma, small cell carcinoma and control subjects. AM were isolated and phagocytic function, flow cytometry and cytokine analysis were assessed. AM from patients with small and squamous cell carcinoma had impaired uptake in vitro of 40 nm fluorescent polystyrene beads. AM from patients with small, squamous and large cell undifferentiated carcinoma showed impaired uptake of 1000 nm fluorescent polystyrene beads. Secreted levels of TNF-alpha and IL-1 from AM of patients with small, squamous, and large cell undifferentiated carcinoma were decreased compared to controls. Secreted AM IL-6 levels were decreased in small and large cell undifferentiated carcinoma. AM from adenocarcinoma patients showed similar levels of IL-10, IL-6, IL-1 and TNF-alpha compared to controls. Phenotypic analysis demonstrated that patients with small cell carcinoma were the only group that showed a decrease in MHC class II surface expression. Surface expression of ICAM-1 and CD83 was decreased on AM from patients with large, squamous and small cell carcinoma compared to controls but not adenocarcinoma. Mannose receptor levels were only decreased on AM from patients with squamous and small cell carcinoma but not adenocarcinoma and large cell undifferentiated carcinoma. We conclude that there are type-specific alterations in uptake ability, cytokine secretion and phenotype of AM from lung cancer patients, which may result in an inability to stimulate anti-tumour immunity. The observed differences between lung cancer subgroups may explain previously reported inconsistencies in descriptions of AM characteristics in lung cancer.

Rational Peptide-based vaccine design for cancer immunotherapeutic applications

Immune responses to cancer cells can be elicited in vivo by administering synthetic peptides derived from proteins uniquely or overexpressed on tumor cells (tumor associated antigens--TAAs). Peptides derived from TAAs are presented in the context of major histocompatibility complex (MHC) molecules to cytotoxic T cells (CTL), which can recognize and lyze tumor cells. In contrast to peptides derived from an exogenous source (viral or bacterial), tumor peptides bind weakly to MHC class I molecules. The low binding affinity of these peptides makes them poor candidates for vaccination due to the poor immunogenic response produced. In order to enhance antigen recognition and hence immunogenicity, peptide binding affinity for MHC can be initially improved by modifying the "anchor" residues. However, the task at hand is highly unpredictable and minor changes in peptide sequence can alter/abolish the T cell response. Furthermore, despite the wealth of information obtained over the last decade from high resolution X-ray structures of MHC class I in complex with peptides (pMHC) as well as pMHC in complex with T cell receptor (TcR), prediction remains difficult. Nonetheless, peptides represent convenient chemical entities that can be rapidly synthesized in clinical grade for therapeutic applications. Herein, the rationale behind modifying TAAs will be discussed including the synthesis/use of proteolytically tolerant peptides (and peptide mimetics) which incorporate non-natural amino acids, retro-inversion and cyclization to improve bioavailability.

Use of the mannan receptor to selectively target vaccine antigens for processing and antigen presentation through the MHC class I and class II pathways

Extensive studies have shown that synthetic and recombinant vaccines developed against hemoparasites have not been as effective as whole parasites or crude membrane fractions in eliciting protective immunity. A possible reason is that synthetic vaccines are not being presented in a form that induces the appropriate immune response. We have developed a bovine model system to evaluate the ability of adjuvant compounds to induce an immune response to peptide antigens dominated by a cytokine profile with a Type 1 (cell-mediated) or Type 2 (humoral) bias. In the initial testing of this system, we found that mRNA expression of certain cytokines (interleukin [IL]-1beta, IL-6, IL-12, IL-15, GM-CSF, iNOS, and tumor necrosis factor [TNF]-alpha) is enhanced when monocyte-derived macrophages are stimulated with peptide antigen conjugated with mannan under oxidizing conditions compared to peptide conjugated with reduced mannan. The data suggest this model will be useful in identifying adjuvant systems that selectively modulate the cytokine profile of antigen presenting cells at the time of antigen presentation and the consequent downstream maturation of naive T cells to effector cells with Type 1 or Type 2 cytokine bias.

Induction of T helper type 1 and 2 responses to 19-kilodalton merozoite surface protein 1 in vaccinated healthy volunteers and adults naturally exposed to malaria

Plasmodium falciparum malaria is a major cause of death in the tropics. The 19-kDa subunit of P. falciparum merozoite surface protein 1 (MSP-1(19)), a major blood stage vaccine candidate, is the target of cellular and humoral immune responses in animals and humans. In this phase I trial of MSP-1(19), immunization of nonexposed human volunteers with either of the two allelic forms of recombinant MSP-1(19) induced high levels of antigen-specific Th1 (gamma interferon) and Th2 (interleukin 4 [IL-4] and IL-10) type lymphokines. The adjustment of the antigen dose and number of immunizations regulated the level of specificity of immune responses and Th1/Th2 bias of responses induced by vaccination. Novel conserved and allelic T-cell epitopes which induced cross-strain immune responses were identified. Importantly, responses to many of these novel epitopes were also present in adults exposed to malaria, both in east (Kenya) and west Africa (The Gambia). These data suggest that epitope-specific naturally acquired MSP-1(19) immune responses in endemic populations can be boosted by vaccination.

Applications of peptide mimetics in cancer

The development of a vaccine for cancer has been difficult compared to the effective vaccines of infectious diseases. Most tumor antigens are not entirely foreign and are expressed on normal tissues, thus, making it difficult to induce strong immune responses against self antigens. A peptide mimic, however, may have the potential to generate greater immune responses than those induced to self peptides. In this review we discuss applications of peptide mimics for cancer immunotherapy which may ultimately prove useful in humans.

Gallium-diffused waveguides in sapphire

The fabrication and characterization of gallium-diffused planar waveguides in sapphire are reported. Waveguides were fabricated by diffusion of 60-200-nm-thick films of gallium oxide into c -cut sapphire at 1600 degrees C for times ranging from 6 to 16 h. Near-field intensity profiles of the guided modes were measured at wavelengths from 488 to 850 nm, and the surface-index elevation was estimated to be up to (0.6+/-0.02)x10(-2) . Potential applications for low-threshold Ti:sapphire waveguide lasers and for optical integrated circuits with passive and active elements in sapphire are discussed.

Getting into the groove: unusual features of peptide binding to MHC class I molecules and implications in vaccine design

The major histocompatibility complex presents antigenic peptides on the surface of antigen presenting cells to T cell receptors. Recognition of peptide-MHC by T cells initiates a cascade of signals in T cells which maintains a T cell dependent immune response. An understanding of the how peptides bind to MHC class I molecules is an important prerequisite in the design of vaccines. Herein, we will discuss, with special emphasis on MUC1, unusual features of MUC1 peptide binding to MHC class I, obtained from vaccine studies including a MUC1 peptide mimic and the crystal structures of low and high affinity peptides lacking canonical anchor motifs in complex with H-2Kb.

Anti-mucin monoclonal antibodies

Mucins are of major interest in cell biology, not only are they highly over-expressed in many adenocarcinomas (up to 40-fold increase), but also have important physiological function, and probably more to be determined (1-3). There is much information available on mucins - doubtless because of their unusual structure being heavily glycosylated, but also containing a repeat region rich in the amino acids serine, threonine and proline. This repeat region confers high immunogenicity of the mucins, and as a result, many antibodies (Abs) have been made to mucins of different species (4). Furthermore, the production of Abs led to the cloning of the cDNAs and armed with these reagents (antibodies, cDNA and genomic structures), advances in the knowledge of the structure and function of mucins has been rapid, together with the development of transgenic and gene knockout animals for biological studies (1-9). Here we describe monoclonal antibodies (Mabs) made to the different mucins, including Mucins 1-4, concentrating on human Mucin 1 (MUC1), to variants of MUC1, to regions outside the VNTR of MUC1, mouse Mucin1 (muc1), unusual features and cross reactions of anti-MUC1 Mabs and Abs made by patients in clinical trials. We will especially describe the Mabs produced in our laboratory.

Designing peptide mimetics for the treatment of multiple sclerosis

Multiple sclerosis is a chronic inflammatory disease of the central nervous system. While the molecular basis of the disease is still unknown, research effort is currently under progress to prevent or ameliorate its effects. There are two major approaches currently in the pursuing of improved therapeutics for the treatment of multiple sclerosis. The first approach focuses on peptide or mimetic therapy and the second on immunotherapy by preventing or controlling disease through the release of appropriate cytokines.

Role of the mannose receptor in the immune response

The mannose receptor (MR) recognizes a range of carbohydrates present on the surface and cell walls of micro-organisms. The MR is primarily expressed on macrophages and dendritic cells and is involved in MR-mediated endocytosis and phagocytosis. In addition, the MR plays a key role in host defense and provides a link between innate and adaptive immunity. Herein, we will review the role of the MR in innate host defense as well as the recent evidence for its role in the adaptive response, for both humoral and cellular immune responses.

Antihypertensive drugs that act on Renin-Angiotensin System with emphasis in AT(1) antagonists

Angiotensin II, the primary active hormone in the Renin-Angiotensin System is a major vasoconstrictor implicated in the cause of hypertension. Research efforts have focused in the treatment of disease by blocking its release and more recently by competing its action on AT(1) receptors. This approach generated in the pharmaceutical market, losartan, and other derivatives. To better understand the stereoelectronic requirements that lead to the molecular basis of hypertension the stereochemical features of angiotensin II and its antagonists are studied.

A 16-mer peptide (RQIKIWFQNRRMKWKK) from antennapedia preferentially targets the Class I pathway

Translocation of antigenic peptides into the cytosol of antigen presenting cells facilitates proteosomal processing and loading into Class I molecules for MHC presentation on the cell surface. The DNA binding domain of the Drosophila transcription factor (Antennapedia), a 60 amino acid protein, is rapidly taken up by cells and has been fused to selected antigens to enhance their immunogenicity. We now demonstrate that a 16 amino acid peptide from antennapedia can facilitate the cytoplasmic uptake of CTL epitope 9-mer peptides. Synthetic peptides were made containing the 16-mer antennapedia peptide linked in tandem to the ovalbumin SIINFEKL CTL peptide. The peptide complex was shown to rapidly internalise into APCs by confocal microscopy. This peptide induced CTL in C57BL/6 mice and protected them against growth of an ovalbumin expressing tumour cell line (E.G7-OVA). The ability of the hybrid peptide to be processed and presented by APCs was similar, whether the SIINFEKL sequence was appended at the C-terminus or N-terminus of the Antennapedia peptide. The production of synthetic peptides containing other CTL peptide epitopes may be useful for priming CTLs in vitro and in vivo

Selection and characterization of MUC1-specific CD8+ T cells from MUC1 transgenic mice immunized with dendritic-carcinoma fusion cells

Mice transgenic for the human MUC1 carcinoma-associated antigen (MUC1.Tg) are tolerant to immunization with MUC1 antigen. Recent studies, however, have demonstrated that immunization of MUC1.Tg mice with fusions of MUC1-positive tumour and dendritic cells (FC/MUC1) reverses MUC1 unresponsiveness and results in rejection of established MUC1-positive pulmonary metastases. Here we demonstrate that lymph node cells from MUC1.Tg mice immunized with the FC/MUC1 fusion cells proliferate in response to MUC1 antigen by a mechanism dependent on the function of CD4, major histocompatibility complex (MHC) class II, B7-1, B7-2, CD28, CD40 and CD40 ligand. The findings demonstrate that stimulation of lymph node cells with MUC1 results in selection of MUC1-specific CD8+ T cells. We show that the CD8+ T cells exhibit MUC1-specific cytotoxic T lymphocyte (CTL) activity by recognition of MUC1 peptides presented in the context of MHC class I molecules Kb and Db. The MUC1-specific CD8+ T cells also exhibit antitumour activity against MUC1-positive metastases, but with no apparent reactivity against normal tissues. These results indicate that immunization of MUC1.Tg mice with FC/MUC1 reverses immunological unresponsiveness to MUC1 by presentation of MUC1 peptides in the presence of costimulatory signals and generates MHC-restricted MUC1-specific CD8+ T cells.

Function and dysfunction of T cell receptor: structural studies

The engagement of the T cell receptor (TCR) to its ligand, the major histocompatibility complex (MHC)-peptide complex, leads to T cell activation. The molecular mechanisms leading to this activation are still unknown. Dimerization or substantial conformational changes following TCR ligation have not been observed by classical biochemical methods or by X-ray crystallography of the TCR/MHC complex. However, most of these experiments have used reductionist approaches in which only MHC and TCR molecules were taken into account. In fact, the TCR is only one of many molecules forming the TCR complex (TCRC), and the interplay among the components of this larger complex have not been studied in depth. The reconstitution of a complete TCRC using recombinant molecules is our goal and will be the first step to new structural and functional studies.

Immunotherapy with mannan-MUC1 and IL-12 in MUC1 transgenic mice

Mice immunised with oxidised mannan-MUC1 fusion protein (M-FP) develop MHC restricted CD8(+) cytotoxic T cells. We now demonstrate that in MUC1/HLA-A2 transgenic mice, IL-12 gives enhanced CTL, CTLp and tumor protection. CTLp in MUC1 transgenic mice with M-FP were 1/55,000, and with IL-12, this increased to 1/19,000, with improved tumor protection. Thus, IL-12 is important for effective CTL responses to MUC1 in transgenic mice.

The I-Ag7 MHC class II molecule linked to murine diabetes is a promiscuous peptide binder

Susceptibility to insulin-dependent diabetes mellitus is linked to MHC class II genes. The only MHC class II molecule expressed by nonobese diabetic (NOD) mice, I-Ag7, shares a common alpha-chain with I-Ad but has a peculiar beta-chain. As with most beta-chain alleles linked to diabetes susceptibility, I-Ag7 contains a nonaspartic residue at position beta57. We have produced large amounts of empty I-Ag7 molecules using a fly expression system to characterize its biochemical properties and peptide binding by phage-displayed peptide libraries. The identification of a specific binding peptide derived from glutamic acid decarboxylase (GAD65) has allowed us to crystallize and obtain the three-dimensional structure of I-Ag7. Structural information was critical in evaluating the binding studies. I-Ag7, like I-Ad, appears to be very promiscuous in terms of peptide binding. Their binding motifs are degenerate and contain small and/or small hydrophobic residues at P4 and P6 of the peptide, a motif frequently found in most globular proteins. The degree of promiscuity is increased for I-Ag7 over I-Ad as a consequence of a larger P9 pocket that can specifically accommodate negatively charged residues, as well as possibly residues with bulky side chains. So, although I-Ad and I-Ag7 are structurally closely related, stable molecules and good peptide binders, they differ functionally in their ability to bind significantly different peptide repertoires that are heavily influenced by the presence or the absence of a negatively charged residue at position 57 of the beta-chain. These characteristics link I-Ag7 with autoimmune diseases, such as insulin-dependent diabetes mellitus.

The evolution of DNA vaccines

Vaccination has eradicated smallpox and greatly decreased mortality and morbidity associated with a variety of viral and bacterial infectious diseases. However, conventional methodologies have failed to provide vaccines against many widespread deadly human diseases, among them HIV, malaria and cancer. Recombinant DNA vaccines have shown great promise in animal models in inducing protective immunity. In this review we will discuss their potential safe use in humans following recent advances in their use in animals, including non-human primates.