Non-monotonic variation with salt concentration of the second virial coefficient in protein solutions

The osmotic virial coefficient $B_2$ of globular protein solutions is calculated as a function of added salt concentration at fixed pH by computer simulations of the ``primitive model''. The salt and counter-ions as well as a discrete charge pattern on the protein surface are explicitly incorporated. For parameters roughly corresponding to lysozyme, we find that $B_2$ first decreases with added salt concentration up to a threshold concentration, then increases to a maximum, and then decreases again upon further raising the ionic strength. Our studies demonstrate that the existence of a discrete charge pattern on the protein surface profoundly influences the effective interactions and that non-linear Poisson Boltzmann and Derjaguin-Landau-Verwey-Overbeek (DLVO) theory fail for large ionic strength. The observed non-monotonicity of $B_2$ is compared to experiments. Implications for protein crystallization are discussed.Comment: 43 pages, including 17 figure

Peptide-targeted PEG-liposomes in anti-angiogenic therapy

Peptides with the RGD amino acid sequence show affinity for the alpha(v)beta(3) integrin, an integrin which is over-expressed on angiogenic endothelium and involved in cell adhesion. A peptide with the sequence ATWLPPR has been demonstrated to show affinity for the vascular endothelial growth factor (VEGF) receptor, a receptor involved in the proliferation of endothelial cells. By coupling these peptides to liposomes, these liposomes can serve as a site-specific drug delivery system to tumor endothelial cells in order to inhibit angiogenesis. In the present study we demonstrate that the coupling of cyclic RGD-peptides or ATWLPPR-peptides to the surface of PEG-liposomes results in binding of these liposomes to endothelial cells in vitro. Subsequent studies with RGD-peptide targeted liposomes in vivo also demonstrate specific binding to the tumor endothelium

Anti-tumor efficacy of tumor vasculature-targeted liposomal doxorubicin

Angiogenesis is a key process in the growth and metastasis of a tumor. Disrupting this process is considered a promising treatment strategy. Therefore, a drug delivery system specifically aiming at angiogenic tumor endothelial cells was developed. Alpha v beta 3-integrins are overexpressed on actively proliferating endothelium and represent a possible target. For this, RGD-peptides with affinity for this integrin were coupled to the distal end of poly(ethylene glycol)-coated long-circulating liposomes (LCL) to obtain a stable long-circulating drug delivery system functioning as a platform for multivalent interaction with alpha v beta 3-integrins. The results show that cyclic RGD-peptide-modified LCL exhibited increased binding to endothelial cells in vitro. Moreover, intravital microscopy demonstrated a specific interaction of these liposomes with tumor vasculature, a characteristic not observed for LCL. RGD-LCL encapsulating doxorubicin inhibited tumor growth in a doxorubicin-insensitive murine C26 colon carcinoma model, whereas doxorubicin in LCL failed to decelerate tumor growth. In conclusion, coupling of RGD to LCL redirected these liposomes to angiogenic endothelial cells in vitro and in vivo. RGD-LCL containing doxorubicin showed superior efficacy over non-targeted LCL in inhibiting C26 doxorubicin-insensitive tumor outgrowth. Likely, these RGD-LCL-doxorubicin antitumor effects are brought about through direct effects on tumor endothelial cells

Enriching lipid nanovesicles with short-chain glucosylceramide improves doxorubicin delivery and efficacy in solid tumors

For amphiphilic anticancer drugs, such as the anthracyclin doxorubicin (Dox), uptake by tumor cells involves slow diffusion across the plasma membrane, a limiting factor in clinical oncology. Previously, we discovered that preinsertion of short-chain sphingolipids such as N-octanoyl-glucosylceramide (GC) in the tumor cell membrane enhances cellular Dox uptake. In the present study, we apply this strategy in vitro and in vivo by coadministering GC and Dox in a lipid nanovesicle (LNV). GC enrichment of Dox-LNVs strongly enhanced in vitro cytotoxicity toward B16 melanoma and A431 carcinoma, as evidenced by 6-fold decreased IC(50) values compared with Dox-LNVs. This correlated with enhanced cellular Dox uptake observed by confocal microscopy. Intravital optical imaging in window chamber-bearing mice with orthotopically implanted B16 melanoma demonstrated enhanced GC-mediated Dox delivery to tumor cells. Treatment of nude mice bearing human A431 xenografts with 6 mg/kg GC-Dox-LNVs almost doubled the tumor growth delay compared with Dox-LNVs. A second administration of 5 mg/kg after 3 d induced even 3-fold delay in tumor growth, while no systemic toxicity was found. GC-enriched Dox-LNVs displayed superior in vitro and in vivo antitumor activity, without systemic toxicity. This new drug delivery concept, aiming at increased membrane permeability for amphiphilic drugs, provides an opportunity to improve cancer chemotherapy.-Van Lummel, M., van Blitterswijk, W. J., Vink, S. R., Veldman, R. J., van der Valk, M. A., Schipper, D., Dicheva, B. M., Eggermont, A. M. M., ten Hagen, T. L. M., Verheij, M., Koning, G. A. Enriching lipid nanovesicles with short-chain glucosylceramide improves doxorubicin delivery and efficacy in solid tumors. FASEB J. 25, 280-289 (2011). www.fasebj.or

Lymph node retrieval during esophagectomy with and without neoadjuvant chemoradiotherapy: prognostic and therapeutic impact on survival.

Item does not contain fulltextOBJECTIVES: We aimed to examine the association between total number of resected nodes and survival in patients after esophagectomy with and without nCRT. BACKGROUND: Most studies concerning the potentially positive effect of extended lymphadenectomy on survival have been performed in patients who underwent surgery alone. As nCRT is known to frequently "sterilize" regional nodes, it is unclear whether extended lymphadenectomy after nCRT is still useful. METHODS: Patients from the randomized CROSS-trial who completed the entire protocol (ie, surgery alone or chemoradiotherapy + surgery) were included. With Cox regression models, we compared the impact of number of resected nodes as well as resected positive nodes on survival in both groups. RESULTS: One hundred sixty-one patients underwent surgery alone, and 159 patients received multimodality treatment. The median (interquartile range) number of resected nodes was 18 (12-27) and 14 (9-21), with 2 (1-6) and 0 (0-1) resected positive nodes, respectively. Persistent lymph node positivity after nCRT had a greater negative prognostic impact on survival as compared with lymph node positivity after surgery alone. The total number of resected nodes was significantly associated with survival for patients in the surgery-alone arm (hazard ratio per 10 additionally resected nodes, 0.76; P=0.007), but not in the multimodality arm (hazard ratio 1.00; P=0.98). CONCLUSIONS: The number of resected nodes had a prognostic impact on survival in patients after surgery alone, but its therapeutic value is still controversial. After nCRT, the number of resected nodes was not associated with survival. These data question the indication for maximization of lymphadenectomy after nCRT.1 november 201

A Valid and reliable method for measuring the kicking accuracy of soccer players

BACKGROUND: Initial results of the ChemoRadiotherapy for Oesophageal cancer followed by Surgery Study (CROSS) comparing neoadjuvant chemoradiotherapy plus surgery versus surgery alone in patients with squamous cell carcinoma and adenocarcinoma of the oesophagus or oesophagogastric junction showed a significant increase in 5-year overall survival in favour of the neoadjuvant chemoradiotherapy plus surgery group after a median of 45 months' follow-up. In this Article, we report the long-term results after a minimum follow-up of 5 years. METHODS: Patients with clinically resectable, locally advanced cancer of the oesophagus or oesophagogastric junction (clinical stage T1N1M0 or T2-3N0-1M0, according to the TNM cancer staging system, sixth edition) were randomly assigned in a 1:1 ratio with permuted blocks of four or six to receive either weekly administration of five cycles of neoadjuvant chemoradiotherapy (intravenous carboplatin [AUC 2 mg/mL per min] and intravenous paclitaxel [50 mg/m(2) of body-surface area] for 23 days) with concurrent radiotherapy (41.4 Gy, given in 23 fractions of 1.8 Gy on 5 days per week) followed by surgery, or surgery alone. The primary endpoint was overall survival, analysed by intention-to-treat. No adverse event data were collected beyond those noted in the initial report of the trial. This trial is registered with the Netherlands Trial Register, number NTR487, and has been completed. FINDINGS: Between March 30, 2004, and Dec 2, 2008, 368 patients from eight participating centres (five academic centres and three large non-academic teaching hospitals) in the Netherlands were enrolled into this study and randomly assigned to the two treatment groups: 180 to surgery plus neoadjuvant chemoradiotherapy and 188 to surgery alone. Two patients in the neoadjuvant chemoradiotherapy group withdrew consent, so a total of 366 patients were analysed (178 in the neoadjuvant chemoradiotherapy plus surgery group and 188 in the surgery alone group). Of 171 patients who received any neoadjuvant chemoradiotherapy in this group, 162 (95%) were able to complete the entire neoadjuvant chemoradiotherapy regimen. After a median follow-up for surviving patients of 84.1 months (range 61.1-116.8, IQR 70.7-96.6), median overall survival was 48.6 months (95% CI 32.1-65.1) in the neoadjuvant chemoradiotherapy plus surgery group and 24.0 months (14.2-33.7) in the surgery alone group (HR 0.68 [95% CI 0.53-0.88]; log-rank p=0.003). Median overall survival for patients with squamous cell carcinomas was 81.6 months (95% CI 47.2-116.0) in the neoadjuvant chemoradiotherapy plus surgery group and 21.1 months (15.4-26.7) in the surgery alone group (HR 0.48 [95% CI 0.28-0.83]; log-rank p=0.008); for patients with adenocarcinomas, it was 43.2 months (24.9-61.4) in the neoadjuvant chemoradiotherapy plus surgery group and 27.1 months (13.0-41.2) in the surgery alone group (HR 0.73 [95% CI 0.55-0.98]; log-rank p=0.038). INTERPRETATION: Long-term follow-up confirms the overall survival benefits for neoadjuvant chemoradiotherapy when added to surgery in patients with resectable oesophageal or oesophagogastric junctional cancer. This improvement is clinically relevant for both squamous cell carcinoma and adenocarcinoma subtypes. Therefore, neoadjuvant chemoradiotherapy according to the CROSS trial followed by surgical resection should be regarded as a standard of care for patients with resectable locally advanced oesophageal or oesophagogastric junctional cancer. FUNDING: Dutch Cancer Foundation (KWF Kankerbestrijding)