Tunable magnetic interaction at the atomic scale in oxide heterostructures

We report on a systematic study of a number of structurally identical but chemically distinct transition metal oxides in order to determine how the material-specific properties such as the composition and the strain affect the properties at the interface of heterostructures. Our study considers a series of structures containing two layers of ferromagnetic SrRuO₃, with antiferromagnetic insulating manganites sandwiched in between. The results demonstrate how to control the strength and relative orientation of interfacial ferromagnetism in correlated electron materials by means of valence state variation and substrate-induced strain, respectively.

Are ankle chondrocytes from damaged fragments a suitable cell source for cartilage repair?

OBJECTIVE

To characterize the post-expansion cartilage-forming capacity of chondrocytes harvested from detached fragments of osteochondral lesions (OCLs) of ankle joints (Damaged Ankle Cartilage Fragments, DACF), with normal ankle cartilage (NAC) as control.

DESIGN

DACF were obtained from six patients (mean age: 35 years) with symptomatic OCLs of the talus, while NAC were from 10 autopsies (mean age: 55 years). Isolated chondrocytes were expanded for two passages and then cultured in pellets for 14 days or onto HYAFF-11 meshes (FAB, Italy) for up to 28 days. Resulting tissues were assessed histologically, biochemically [glycosaminoglycan (GAG), DNA and type II collagen (CII)] and biomechanically.

RESULTS

As compared to NAC, DACF contained significantly lower amounts of DNA (3.0-fold), GAG (5.3-fold) and CII (1.5-fold) and higher amounts of type I collagen (6.2-fold). Following 14 days of culture in pellets, DACF-chondrocytes generated tissues less intensely stained for Safranin-O and CII, with significantly lower GAG contents (2.8-fold). After 28 days of culture onto HYAFF((R))-11, tissues generated by DACF-chondrocytes were less intensely stained for Safranin-O and CII, contained significantly lower amounts of GAG (1.9-fold) and CII (1.4-fold) and had lower equilibrium (1.7-fold) and dynamic pulsatile modulus (3.3-fold) than NAC-chondrocytes.

CONCLUSION

We demonstrated that DACF-chondrocytes have inferior cartilage-forming capacity as compared to NAC-chondrocytes, possibly resulting from environmental changes associated with trauma/disease. The study opens some reservations on the use of DACF-derived cells for the repair of ankle cartilage defects, especially in the context of tissue engineering-based approaches.

Ceramic materials lead to underestimated DNA quantifications: a method for reliable measurements

In the context of investigating cell-material interactions or of material-guided generation of tissues, DNA quantification represents an elective method to precisely assess the number of cells attached or embedded within different substrates. Nonetheless, nucleic acids are known to electrostatically bind to ceramics, a class of materials commonly employed in orthopaedic implants and bone tissue engineering scaffolds. This phenomenon is expected to lead to a relevant underestimation of the DNA amount, resulting in erroneous experimental readouts. The present work aims at *lpar;i) investigating the effects of DNA-ceramic bond occurrence on DNA quantification, and (ii) developing a method to reliably extract and accurately quantify DNA in ceramic-containing specimens. A cell-free model was adopted to study DNA-ceramic binding, highlighting an evident DNA loss (up to 90%) over a wide range of DNA/ceramic ratios (w/w). A phosphate buffer-based (800 mM) enzymatic extraction protocol was developed and its efficacy in terms of reliable DNA extraction and measurement was confirmed with commonly used fluorometric assays, for various ceramic substrates. The proposed buffered DNA extraction technique was validated in a cell-based experiment showing 95% DNA retrieval in a cell seeding experiment, demonstrating a 3.5-fold increase in measured DNA amount as compared to a conventional enzymatic extraction protocol. In conclusion, the proposed phosphate buffer method consistently improves the DNA extraction process assuring unbiased analysis of samples and allowing accurate and sensitive cell number quantification on ceramic containing substrates.

Genes mediating programmed cell death: an immunohistochemical study of bcl-2, c-myc and p53 expression in colorectal neoplasia

Aims-To describe the expression of three genes involved in the regulation of cell proliferation and programmed cell death (apoptosis) in normal, dysplastic and malignant large bowel epithelium, and to relate any alterations to important biological and clinical variables.Methods-Immunohistochemistry was used to assess bcl-2, c-myc and p53 gene expression in 70 colorectal carcinomas, 36 adenomas and three samples of normal mucosa.Results-Bcl-2 and c-myc protein were detected in all samples of normal mucosa and most adenomas. P53 was never found in normal mucosa and was expressed in only 5% of adenomas. Sixty nine of 70 carcinomas expressed c-myc protein; p53 was found in 46% and bcl-2 was present in 35%. Bcl-2 expression correlated with a higher degree of tumour differentiation whereas the opposite was true for c-myc. Strong staining for c-myc protein predicted survival in univariate analysis. No correlation was found between p53 and bcl-2 expression.Conclusions-While c-myc and bcl-2 proteins are overexpressed at an early stage of the large bowel adenoma-carcinoma sequence, alterations to the p53 protein level only occur as a late event in large, highly dysplastic adenomas and carcinomas. Bcl-2 may therefore protect the growing adenoma against excessive programmed cell death and mutated p53 may play a similar role in carcinomas. In vitro there is a reciprocal relation between p53 and bcl-2 expression. This could not be confirmed in vivo. Similarly, there was no relation between bcl-2 and c-myc status, despite evidence that these proteins cooperate to cause neoplastic transformation. C-myc may be a prognostic indicator in large bowel cancer. There is no evidence in the present series that bcl-2 status will affect survival.

Towards an intraoperative engineering of osteogenic and vasculogenic grafts from the stromal vascular fraction of human adipose tissue

Grafts generated by cultivation of progenitor cells from the stromal vascular fraction of human adipose tissue have been proven to have osteogenic and vasculogenic properties in vivo. However, in vitro manufacture of such implants is challenged by complex, impractical and expensive processes, and requires implantation in a separate surgery. This study investigates the feasibility of an intraoperative approach to engineer cell-based bone grafts with tissue harvest, cell isolation, cell seeding onto a scaffold and subsequent implantation within a few hours. Freshly isolated adipose tissue cells from a total of 11 donors, containing variable fractions of mesenchymal and endothelial progenitors, were embedded at different densities in a fibrin hydrogel, which was wrapped around bone substitute materials based on beta-tricalcium phosphate (ChronOS), hydroxyapatite (Engipore), or acellular xenograft (Bio-Oss). The resulting constructs, generated within 3 hours from biopsy harvest, were immediately implanted ectopically in nude mice and analysed after eight weeks. All explants contained blood vessels formed by human endothelial cells, functionally connected to the recipient's vasculature. Human origin cells were also found within osteoid structures, positively immunostained for bone sialoprotein and osteocalcin. However, even with the highest loaded cell densities, no frank bone tissue was detected, independently of the material used. These results provide a proof-of-principle that an intraoperative engineering of autologous cell-based vasculogenic bone substitutes is feasible, but highlight that - in the absence of in vitro commitment--additional cues (e.g., low dose of osteogenic factors or orthotopic environmental conditions) are likely needed to support complete osteoblastic cell differentiation and bone tissue generation.

Structure and energetics of azobenzene on Ag(111): benchmarking semiempirical dispersion correction approaches

We employ normal-incidence x-ray standing wave and temperature programed desorption spectroscopy to derive the adsorption geometry and energetics of the prototypical molecular switch azobenzene at Ag(111). This allows us to assess the accuracy of semiempirical correction schemes as a computationally efficient means to overcome the deficiency of semilocal density-functional theory with respect to long-range van der Waals (vdW) interactions. The obtained agreement underscores the significant improvement provided by the account of vdW interactions, with remaining differences mainly attributed to the neglect of electronic screening at the metallic surface.

Investigation of the exclusive 3He(e,e' pn)1H reaction

Cross sections for the 3He(e,e' pn)1H reaction were measured for the first time at energy transfers of 220 and 270 MeV for several momentum transfers ranging from 300 to 450 MeV/c. Cross sections are presented as a function of the momentum of the recoil proton and the momentum transfer. Continuum Faddeev calculations using the Argonne V18 and Bonn-B nucleon-nucleon potentials overestimate the measured cross sections by a factor 5 at low recoil proton momentum with the discrepancy becoming smaller at higher recoil proton momentum.

Maternal serum screening for trisomy 21 in women with a false positive result in last pregnancy

Maternal serum screening for Down syndrome is a common practice in the United Kingdom. A number of factors have been shown to influence the chance of a false positive test result. Analysis of routinely collated information stored on an electronic database in a district general hospital has shown that women with a previous false positive maternal screen are at much greater chance of having a false positive result in their next pregnancy. Overall, there was a fivefold increased risk attributed to biological variation in their serum concentrations of alpha-feto protein (AFP) and human chorionic gonadotrophin (hCG). The potential effect of this was to increase the chance of such women having an unnecessary amniocentesis. Women should be advised of this effect in subsequent pregnancies. Ideally a correction factor should be applied which would reduce the false positive rate without affecting adversely the sensitivity of the test.

Incidence of chemotherapy-induced nausea and vomiting in 2008

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Background: The authors determined the incidence of acute and delayed chemotherapy-induced nausea and vomiting (CINV) among new patients (pts) receiving chemotherapy with modern antiemetic prophylaxis in 2008. Methods: A prospective observational study of adult cancer pts receiving, for the first time, moderately or highly emetogenic chemotherapy (MEC or HEC) was performed. Study participants were called on day 2 and day 8, after first and second cycle, to evaluate acute and delayed emesis according a 10-item questionnaire. All patients received, before and after their chemotherapy, the optimal antiemetic prophylaxis according to the 2006 Update of ASCO Guideline for Antiemetics. Results: 131 consecutive pts were enrolled between January and June 2008. At cycle 1, on 124 assessable pts for acute emesis: 68 pts received MEC and 18, HEC. 5.6% developed acute vomiting (5.9% for MEC and 5.6% for HEC) and 33.1%, acute nausea (39.7% for MEC and 44.4% for HEC). At cycle 1, on 101 assessable pts for delayed emesis: 5% experienced delayed vomiting (5.1% for MEC and 6.3% for HEC) and 17.8%, delayed nausea (18.6% for MEC and 31.3% for HEC). At cycle 2, on 121 assessable pts for acute emesis: 62 pts received MEC and 18, HEC. 8.3% developed acute vomiting (6.5% for MEC and 16.3% for HEC) and 31.4%, acute nausea (35.5% for MEC and 44.4% for HEC). At cycle 2, on 96 assessable pts for delayed emesis: 5.2% experienced delayed vomiting (3.3% for MEC and 9.1% for HEC) and 19.8%, delayed nausea (23% for MEC and 27.3% for HEC). Conclusions: Though the application of the last antiemetic recommendations, CINV, especially nausea, remained a substantial toxicity for patients receiving chemotherapy, pointing out the need for improved therapeutic intervention.

[Table: see text]

Risk factors in the population of the GDR-MONICA Study (1983/84)

The GDR-MONICA project comprises 25 administratively defined areas with a population of nearly two million people aged 25-64. Data from the first random sample survey are reported here. The survey gathered information regarding risk factors, dietary behaviour, physical activity and psychosocial factors from 11,281 persons aged 25-64. The average risk factor levels were high in the population: The mean casual blood pressure was 140/88 mmHg and 138/86 mmHg for men and women respectively. In both sexes the mean total cholesterol level exceeded 6.1 mmol/L, and the mean body mass index (BMI) was just over 26.0. The study population consumed, on average, excessive amounts of energy, fat, alcohol, and sodium, and too few carbohydrates. Preliminary conclusions regarding unfavourable trends in risk factor levels have been drawn by comparing the present data with other recent reliable epidemiological studies.

Intra-individual comparison of human ankle and knee chondrocytes in vitro: relevance for talar cartilage repair

OBJECTIVE

As compared to knee chondrocytes (KC), talar chondrocytes (TC) have superior synthetic activity and increased resistance to catabolic stimuli. We investigated whether these properties are maintained after TC are isolated and expanded in vitro.

METHODS

Human TC and KC from 10 cadavers were expanded in monolayer and then cultured in pellets for 3 and 14 days or in hyaluronan meshes (Hyaff-11) for 14 and 28 days. Resulting tissues were assessed biochemically, histologically, biomechanically and by real-time reverse transcriptase-polymerase chain reaction (RT-PCR). The proteoglycan and collagen synthesis rates in the pellets were also measured following exposure to Interleukin-1 beta (IL-1 beta).

RESULTS

After 14 days of pellet culture, TC and KC expressed similar levels of type I collagen (CI) and type II collagen (CII) mRNA and the resulting tissues contained comparable amounts of glycosaminoglycans (GAG) and displayed similar staining intensities for CII. Also proteoglycan and collagen synthesis were similar in TC and KC pellets, and dropped to a comparable extent in response to IL-1 beta. Following 14 days of culture in Hyaff-11, TC and KC generated tissues with similar amounts of GAG and CI and CII. After 28 days, KC deposited significantly larger fractions of GAG and CII than TC, although the trend was not reflected in the measured biomechanical properties.

CONCLUSION

After isolation from their original matrices and culture expansion, TC and KC displayed similar biosynthetic activities, even in the presence of catabolic stimuli. These in vitro data suggest a possible equivalence of TC and KC as autologous cell sources for the repair of talar cartilage lesions.

Prognostic value of maximum standardized uptake values from preoperative positron emission tomography in resectable adenocarcinoma of the esophagus treated by surgery alone

Preoperative staging for esophageal adenocarcinoma is suboptimal for predicting outcomes when compared with pathological data. The aim of this study was to assess if the quantitative values obtained by preoperative 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) are independent prognostic indicators for survival in patients with resectable adenocarcinoma of the esophagus undergoing surgical treatment without neoadjuvant therapy. Patients were identified from a prospective database, survival analyses were undertaken using log rank and Cox method. The median follow-up was 44 months (range 18-61 months). Between November 2002 and November 2005, 45 consecutive patients underwent FDG-PET followed by surgery. The median age was 72 years (range 38-82 years). On univariate analysis of overall survival and disease-free survival, preoperative FDG-PET maximum standardized uptake value (SUV(max); P= 0.008 and P= 0.015, respectively) and postoperative pathological stage (P= 0.001 and P= 0.001, respectively) as well as postoperative histological grade (P= 0.001 and P= 0.001, respectively) were significantly associated with outcome. Multivariate analysis demonstrated that only the postoperative pathological variables were independent predictors of outcome (Wald 11.81, P= 0.001). Preoperative FDG-PET SUV(max) is associated with outcome after esophageal adenocarcinoma resection but remains less accurate than postoperative variables. A high FDG-PET SUV(max) could be used to identify a high-risk population who would benefit most from neoadjuvant therapies.

Cartilage tissue engineering using pre-aggregated human articular chondrocytes

In this study, we first aimed at determining whether human articular chondrocytes (HAC) proliferate in aggregates in the presence of strong chondrocyte mitogens. We then investigated if the aggregated cells have an enhanced chondrogenic capacity as compared to cells cultured in monolayer. HAC from four donors were cultured in tissue culture dishes either untreated or coated with 1% agarose in the presence of TGFbeta-1, FGF-2 and PDGF-BB. Proliferation and stage of differentiation were assessed by measuring respectively DNA contents and type II collagen mRNA. Expanded cells were induced to differentiate in pellets or in Hyaff-11 meshes and the formed tissues were analysed biochemically for glycosaminoglycans (GAG) and DNA, and histologically by Safranin O staining. The amount of DNA in aggregate cultures increased significantly from day 2 to day 6 (by 3.2-fold), but did not further increase with additional culture time. Expression of type II collagen mRNA was about two orders of magnitude higher in aggregated HAC as compared to monolayer expanded cells. Pellets generated by aggregated HAC were generally more intensely stained for GAG than those generated by monolayer-expanded cells. Scaffolds seeded with aggregates accumulated more GAG (1.3-fold) than scaffolds seeded with monolayer expanded HAC. In conclusion, this study showed that HAC culture in aggregates does not support a relevant degree of expansion. However, aggregation of expanded HAC prior to loading into a porous scaffold enhances the quality of the resulting tissues and could thus be introduced as an intermediate culture phase in the manufacture of engineered cartilage grafts.

Search for gravitational-wave bursts from soft gamma repeaters

We present a LIGO search for short-duration gravitational waves (GWs) associated with soft gamma ray repeater (SGR) bursts. This is the first search sensitive to neutron star f modes, usually considered the most efficient GW emitting modes. We find no evidence of GWs associated with any SGR burst in a sample consisting of the 27 Dec. 2004 giant flare from SGR 1806-20 and 190 lesser events from SGR 1806-20 and SGR 1900+14. The unprecedented sensitivity of the detectors allows us to set the most stringent limits on transient GW amplitudes published to date. We find upper limit estimates on the model-dependent isotropic GW emission energies (at a nominal distance of 10 kpc) between 3x10;{45} and 9x10;{52} erg depending on waveform type, detector antenna factors and noise characteristics at the time of the burst. These upper limits are within the theoretically predicted range of some SGR models.

Kondo stripes in an Anderson-Heisenberg model of heavy fermion systems

We study the interplay between the spin-liquid and Kondo physics, as related to the nonmagnetic part of the phase diagram of heavy fermion materials. Within the unrestricted mean-field treatment of the infinite-U 2D Anderson-Heisenberg model, we find that there are two topologically distinct nondegenerate uniform heavy Fermi liquid states that may form as a consequence of the Kondo coupling between spinons and conduction electrons. For certain carrier concentrations, the uniform Fermi liquid becomes unstable with respect to the formation of a new kind of anharmonic "Kondo stripe" state with inhomogeneous Kondo screening strength and the charge density modulation. These features are experimentally measurable and thus may help to establish the relevance of the spin-liquid correlations to heavy fermion materials.

Local ferromagnetic resonance imaging with magnetic resonance force microscopy

We report nanoscale scanned probe ferromagnetic resonance force microscopy (FMRFM) imaging of individual ferromagnetic microstructures. This reveals the mechanism for high spatial resolution in FMRFM imaging: the strongly inhomogeneous local magnetic field of the cantilever mounted micromagnetic probe magnet used in FMRFM enables selective, local excitation of ferromagnetic resonance (FMR). This approach, demonstrated here in individual permalloy disks, is straightforwardly extended to excitation of localized FMR modes, and hence imaging in extended films.

Positron emission tomography and pathological evidence of response to neoadjuvant therapy in adenocarcinoma of the esophagus

Our aim was to determine if fluorodeoxyglucose positron emission tomography (FDG-PET) could be correlated with a pathological response in patients with esophageal adenocarcinoma receiving neoadjuvant chemotherapy and/or chemoradiation therapy. Patients with resectable, histologically proven adenocarcinoma of the esophagus were entered in the study. Preoperative chemotherapy comprised two cycles of cisplatin and 5-fluorouracil. Radiation therapy commenced with the second cycle on day 22. FDG-PET images were obtained pre-treatment and on completion of intended neo-adjuvant treatment. Quantification was achieved by the calculation of both standardized uptake values (SUV) and tumor/liver ratios (TLR). Evidence of histopathological response was identified according to the Mandard tumor regression scoring system. There were 45 patients, 22 receiving neoadjuvant chemotherapy and 23 chemoradiation therapy. Forty patients underwent surgical resection. Seven patients (16%) had a histopathological response. The mean percentage change in SUV in the histological responders group was -56.8% (SD 29) and in the non-responders -27.8% (SD 32.1) (P = 0.035). The mean percentage change in TLR was -49.1% (SD 44.8) in the responders and in the non-responders -27.3% (SD 31.3) (P = 0.128). There was no difference between the two methods of assessment, however there was less variation with SUV. There was no correlation between the FDG-PET response and the histopathological response. Presently an FDG-PET scan performed 3-6 weeks after neoadjuvant therapy for adenocarcinoma of the esophagus should not be used as a marker of the potential result of the treatment. The optimal timing of a second FDG-PET remains unclear.

Engineered cartilage generated by nasal chondrocytes is responsive to physical forces resembling joint loading

OBJECTIVE

To determine whether engineered cartilage generated by nasal chondrocytes (ECN) is responsive to different regimens of loading associated with joint kinematics and previously shown to be stimulatory of engineered cartilage generated by articular chondrocytes (ECA).

METHODS

Human nasal and articular chondrocytes, harvested from 5 individuals, were expanded and cultured for 2 weeks into porous polymeric scaffolds. The resulting ECN and ECA were then maintained under static conditions or exposed to the following loading regimens: regimen 1, single application of cyclic deformation for 30 minutes; regimen 2, intermittent application of cyclic deformation for a total of 10 days, followed by static culture for 2 weeks; regimen 3, application of surface motion for a total of 10 days.

RESULTS

Prior to loading, ECN constructs contained significantly higher amounts of glycosaminoglycan (GAG) and type II collagen compared with ECA constructs. ECN responded to regimen 1 by increasing collagen and proteoglycan synthesis, to regimen 2 by increasing the accumulation of GAG and type II collagen as well as the dynamic modulus, and to regimen 3 by increasing the expression of superficial zone protein, at the messenger RNA level and the protein level, as well as the release of hyaluronan. ECA constructs were overall less responsive to all loading regimens, likely due to the lower extracellular matrix content.

CONCLUSION

Human ECN is responsive to physical forces resembling joint loading and can up-regulate molecules typically involved in joint lubrication. These findings should prompt future in vivo studies exploring the possibility of using nasal chondrocytes as a cell source for articular cartilage repair.

A low percentage of autologous serum can replace bovine serum to engineer human nasal cartilage

For the generation of cell-based therapeutic products, it would be preferable to avoid the use of animal-derived components. Our study thus aimed at investigating the possibility to replace foetal bovine serum (FBS) with autologous serum (AS) for the engineering of cartilage grafts using expanded human nasal chondrocytes (HNC). HNC isolated from 7 donors were expanded in medium containing 10% FBS or AS at different concentrations (2%, 5% and 10%) and cultured in pellets using serum-free medium or in Hyaff(R)-11 meshes using medium containing FBS or AS. Tissue forming capacity was assessed histologically (Safranin O), immunohistochemically (type II collagen) and biochemically (glycosaminoglycans -GAG- and DNA). Differences among experimental groups were assessed by Mann Whitney tests. HNC expanded under the different serum conditions proliferated at comparable rates and generated cartilaginous pellets with similar histological appearance and amounts of GAG. Tissues generated by HNC from different donors cultured in Hyaff(R)-11 had variable quality, but the accumulated GAG amounts were comparable among the different serum conditions. Staining intensity for collagen type II was consistent with GAG deposition. Among the different serum conditions tested, the use of 2% AS resulted in the lowest variability in the GAG contents of generated tissues. In conclusion, a low percentage of AS can replace FBS both during the expansion and differentiation of HNC and reduce the variability in the quality of the resulting engineered cartilage tissues.

Laparoscopic distal pancreatectomy: the Brisbane experience of forty-six cases

BACKGROUND AND AIMS

Laparoscopic distal pancreatectomy (LDP) is a safe alternative to conventional open distal pancreatectomy, with advantages that include smaller incisions, less pain, and shorter postoperative recovery. Despite these apparent advantages, however, uptake of the procedure has been slow, with only a handful of series published.

MATERIAL AND METHODS

All LDPs performed in Brisbane, Australia, over a 10-year period (May 1996 to June 2006) were retrospectively reviewed.

RESULTS

Forty-six consecutive LDPs were performed. A variety of lesions were resected, including nine cancers. Twelve patients were converted for oncological (6) or technical reasons (6). The spleen was retained in 14/29 patients, either by main splenic vessel preservation (9) or solely supported by the short gastric vessels (5), resulting in inferior pole infarction in 2 patients. Overall morbidity was 39%, including 15% pancreatic fistula. All fistulas resolved after a median of 6 weeks without re-operation. A non-significant trend toward fewer fistulas with stapled rather than sutured stump closure was observed (13% vs 19%; p=0.43). Median operative duration and hospital stay were 157 min and 7 days, respectively. There was no mortality.

CONCLUSION

LDP is a safe alternative to conventional resection for a wide range of lesions. As with open resection, pancreatic fistula is the dominant morbidity, but is generally indolent. While spleen preservation is often possible, care must be taken to avoid infarction of the inferior pole if the Warshaw technique is utilized.

Conserved dimeric subunit stoichiometry of SLC26 multifunctional anion exchangers

The SLC26 gene family encodes multifunctional transport proteins in numerous tissues and organs. Some paralogs function as anion exchangers, others as anion channels, and one, prestin (SLC26A5), represents a membrane-bound motor protein in outer hair cells of the inner ear. At present, little is known about the molecular basis of this functional diversity. We studied the subunit stoichiometry of one bacterial, one teleost, and two mammalian SLC26 isoforms expressed in Xenopus laevis oocytes or in mammalian cells using blue native PAGE and chemical cross-linking. All tested SLC26s are assembled as dimers composed of two identical subunits. Co-expression of two mutant prestins with distinct voltage-dependent capacitances results in motor proteins with novel electrical properties, indicating that the two subunits do not function independently. Our results indicate that an evolutionarily conserved dimeric quaternary structure represents the native and functional state of SLC26 transporters.

Outcomes from salvage esophagectomy post definitive chemoradiotherapy compared with resection following preoperative neoadjuvant chemoradiotherapy

Chemoradiotherapy (CRT) as a definitive treatment for esophageal cancer, is being used with increasing frequency and as a result, surgeons will be required to assess more patients who have residual or recurrent local malignancy. This article aimed to assess outcomes after esophagectomy following definitive CRT (dCRT) and compare any difference between them and patients who had preoperative neoadjuvant CRT (nCRT) using a similar regimen of chemotherapy. From a prospective database the details of patients who had a resection following nCRT and dCRT were analyzed. The main therapeutic difference between the groups was the dose of radiotherapy (35 vs 60 Gy) and the timing of the resection following completion of the CRT (median 4 vs 28 weeks). Fourteen patients had an esophagectomy following a dCRT and 53 had one following a nCRT. Preoperatively, the dCRT group had worse respiratory function and more ECG abnormalities. Preoperative tumor length, pathological TNM staging and R0 resection rates were the same in both groups. Post resection, the dCRT group had greater morbidity than the nCRT group, spending longer in the intensive care unit (median 48 vs 24 h), more days in hospital (median 31 vs 13) and having more severe respiratory complications (37%vs 6%). The operative mortality was higher in the dCRT group (7%vs 0%). The three-year survival was 24% after dCRT. Patients selected for salvage esophagectomy following dCRT are a major challenge in postoperative care. However, some patients survive for a reasonable period of time, making resection a worthwhile option.

Measurement of energy eigenstates by a slow detector

We propose a method for a weak continuous measurement of the energy eigenstates of a fast quantum system by means of a slow detector. Such a detector is sensitive only to slowly changing variables, e.g., energy, while its backaction can be limited solely to decoherence of the eigenstate superpositions. We apply this scheme to the problem of detection of quantum jumps between energy eigenstates in a harmonic oscillator.

Multiple mechanisms underlie defective recognition of melanoma cells cultured in three-dimensional architectures by antigen-specific cytotoxic T lymphocytes

Cancer cells' growth in three-dimensional (3D) architectures promotes resistance to drugs, cytokines, or irradiation. We investigated effects of 3D culture as compared to monolayers (2D) on melanoma cells' recognition by tumour-associated antigen (TAA)-specific HLA-A(*)0201-restricted cytotoxic T-lymphocytes (CTL). Culture of HBL, D10 (both HLA-A(*)0201+, TAA+) and NA8 (HLA-A(*)0201+, TAA-) melanoma cells on polyHEMA-coated plates, resulted in generation of 3D multicellular tumour spheroids (MCTS). Interferon-gamma (IFN-gamma) production by HLA-A(*)0201-restricted Melan-A/MART-1(27-35) or gp 100(280-288)-specific CTL clones served as immunorecognition marker. Co-culture with melanoma MCTS, resulted in defective TAA recognition by CTL as compared to 2D as witnessed by decreased IFN-gamma production and decreased Fas Ligand, perforin and granzyme B gene expression. A multiplicity of mechanisms were potentially involved. First, MCTS per se limit CTL capacity of recognising HLA class I restricted antigens by reducing exposed cell surfaces. Second, expression of melanoma differentiation antigens is downregulated in MCTS. Third, expression of HLA class I molecules can be downregulated in melanoma MCTS, possibly due to decreased interferon-regulating factor-1 gene expression. Fourth, lactic acid production is increased in MCTS, as compared to 2D. These data suggest that melanoma cells growing in 3D, even in the absence of immune selection, feature characteristics capable of dramatically inhibiting TAA recognition by specific CTL.

Differential cartilaginous tissue formation by human synovial membrane, fat pad, meniscus cells and articular chondrocytes

OBJECTIVE

To identify an appropriate cell source for the generation of meniscus substitutes, among those which would be available by arthroscopy of injured knee joints.

METHODS

Human inner meniscus cells, fat pad cells (FPC), synovial membrane cells (SMC) and articular chondrocytes (AC) were expanded with or without specific growth factors (Transforming growth factor-beta1, Fibroblast growth factor-2 and Platelet-derived growth factor bb, TFP) and then induced to form three-dimensional cartilaginous tissues in pellet cultures, or using a hyaluronan-based scaffold (Hyaff-11), in culture or in nude mice. Human native menisci were assessed as reference.

RESULTS

Cell expansion with TFP enhanced glycosaminoglycan (GAG) deposition by all cell types (up to 4.1-fold) and messenger RNA expression of collagen type II by FPC and SMC (up to 472-fold) following pellet culture. In all models, tissues generated by AC contained the highest fractions of GAG (up to 1.9% of wet weight) and were positively stained for collagen type II (specific of the inner avascular region of meniscus), type IV (mainly present in the outer vascularized region of meniscus) and types I, III and VI (common to both meniscus regions). Instead, inner meniscus, FPC and SMC developed tissues containing negligible GAG and no detectable collagen type II protein. Tissues generated by AC remained biochemically and phenotypically stable upon ectopic implantation.

CONCLUSIONS

Under our experimental conditions, only AC generated tissues containing relevant amounts of GAG and with cell phenotypes compatible with those of the inner and outer meniscus regions. Instead, the other investigated cell sources formed tissues resembling only the outer region of meniscus. It remains to be determined whether grafts based on AC will have the ability to reach the complex structural and functional organization typical of meniscus tissue.