Photo-responsive supramolecular polymer bottle-brushes: The key role of the solvent on self-assembly and responsiveness

HYPOTHESIS

Supramolecular polymer bottlebrushes (SPBs) consist in the 1D self-assembly of building blocks composed of a self-assembling core with pendant polymer arms. Kinetic hurdles often hinder their stimuli-responsiveness in solution. Changing the nature of the solvent should alleviate these hurdles by modulating the self-association strength, leading to stimuli-responsive SPBs.

EXPERIMENTS

The SPBs were formed, in various solvents, by hydrogen bond-driven self-assembly of an azobenzene-bisurea decorated with poly(ethylene oxide) polymer arms. The photo-isomerization of the azobenzene unit was studied by UV/visible spectroscopy and proton NMR spectroscopy, whereas the consequences on supramolecular self-assembly were studied by small angle neutron and X-ray scattering.

FINDINGS

In water, the assembly was previously shown to be driven by both hydrogen-bonds and strong hydrophobic effects, the latter rendering the system kinetically frozen and the disassembly irreversible. Here we show that in organic solvents such as toluene or chloroform, reversible light-responsive dissociation is achieved. Solvophobic effects in these solvents are expected to be much weaker than in water, which probably allows reversibility of the light-response in the former solvents. The key role of the solvent on the reversibility of the process opens up new perspectives for the design of stimuli-responsive SPBs and their applications in various fields.

Facet-Dependent Strain Determination in Electrochemically Synthetized Platinum Model Catalytic Nanoparticles

Studying model nanoparticles is one approach to better understand the structural evolution of a catalyst during reactions. These nanoparticles feature well-defined faceting, offering the possibility to extract structural information as a function of facet orientation and compare it to theoretical simulations. Using Bragg Coherent X-ray Diffraction Imaging, the uniformity of electrochemically synthesized model catalysts is studied, here high-index faceted tetrahexahedral (THH) platinum nanoparticles at ambient conditions. 3D images of an individual nanoparticle are obtained, assessing not only its shape but also the specific components of the displacement and strain fields both at the surface of the nanocrystal and inside. The study reveals structural diversity of shapes and defects, and shows that the THH platinum nanoparticles present strain build-up close to facets and edges. A facet recognition algorithm is further applied to the imaged nanoparticles and provides facet-dependent structural information for all measured nanoparticles. In the context of strain engineering for model catalysts, this study provides insight into the shape-controlled synthesis of platinum nanoparticles with high-index facets.

Evaluation of intragranular strain and average dislocation density in single grains of a polycrystal using K-map scanning

Quick scanning X-ray microscopy combined with three-dimensional reciprocal space mapping was applied to characterize intragranular orientation and strain in a single grain of uniaxially deformed Al polycrystal. The strain component perpendicular to the direction of the applied tensile load was found to be very heterogeneous with high compressive and tensile values in the grain interior and near two grain boundaries, respectively. The distribution of the magnitude of diffraction vectors indicates that dislocations are the origin of the strain. The work opens new possibilities for analysing dislocation structures and intragranular residual stress/strain in single grains of polycrystalline materials.

Compact ultrahigh vacuum sample environments for x-ray nanobeam diffraction and imaging

X-ray nanobeams present the opportunity to obtain structural insight in materials with small volumes or nanoscale heterogeneity. The effective spatial resolution of the information derived from nanobeam techniques depends on the stability and precision with which the relative position of the x-ray optics and sample can be controlled. Nanobeam techniques include diffraction, imaging, and coherent scattering, with applications throughout materials science and condensed matter physics. Sample positioning is a significant mechanical challenge for x-ray instrumentation providing vacuum or controlled gas environments at elevated temperatures. Such environments often have masses that are too large for nanopositioners capable of the required positional accuracy of the order of a small fraction of the x-ray spot size. Similarly, the need to place x-ray optics as close as 1 cm to the sample places a constraint on the overall size of the sample environment. We illustrate a solution to the mechanical challenge in which compact ion-pumped ultrahigh vacuum chambers with masses of 1-2 kg are integrated with nanopositioners. The overall size of the environment is sufficiently small to allow their use with zone-plate focusing optics. We describe the design of sample environments for elevated-temperature nanobeam diffraction experiments demonstrate in situ diffraction, reflectivity, and scanning nanobeam imaging of the ripening of Au crystallites on Si substrates.

A phase II randomized study comparing navelbine and capecitabine (Navcap) followed either by Navcap or by weekly docetaxel in the first-line treatment of HER-2/neu negative metastatic breast cancer

Following the proven efficacy and tolerability of Navcap and Navcap followed by docetaxel in the treatment of MBC, a phase II randomized study was initiated to assess the ORR of both arms in the first-line setting of MBC. Patients with no prior chemotherapy for MBC and HER-2/neu negative were eligible. All patients received Navcap (V 25 mg/m2 on d1 and d8 and C 825 mg/m2 bid D1-14 q3w) for a total of 4 cycles. Patients progressing under Navcap were withdrawn and received docetaxel as second-line treatment. Patients responding or stable were randomized to 2 arms: 4 cycles of Navcap (A) or 12 weekly docetaxel (25 mg/m²/week) (B). From July 2004 to July 2008, a total of 106 patients were enrolled. Ninety-four patients were evaluable before randomization, with a clinical benefit of 58%. Twenty-one patients (22%) had disease progression and were therefore not randomized. Forty-one patients were randomized to arm A and 29 patients to arm B. ORRs were 56 and 71% in arms A and B, respectively. The median time to progression and overall survival were 10 and 35 months in arm A and 12 and 37 months in arm B. Adverse events were mild. Arm A: grade 3-4 neutropenia (10%), grade 3 anemia (5%). Arm B: grade 3 neutropenia (6%), grade 3 anemia (6.2%), and grade 2 alopecia (12%).

CONCLUSION

Both Navcap and Navcap followed by Docetaxel regimens were tolerated with manageable toxicity, offering consistent activities in terms of response rate for metastatic breast cancer patients.

Collective molecular reorientation of a calamitic liquid crystal (12CB) confined in alumina nanochannels

We study the smectic director structure of the rodlike liquid crystal 4-n-dodecyl-4'-cyanobiphenyl (12CB) confined in cylindrical cavities of 200 nm diameter in porous alumina templates by means of combined broadband dielectric spectroscopy, optical birefringence, and neutron scattering measurements. We show that the collective molecular orientation differs between entering the smectic A phase upon cooling from the isotropic state and entering the same phase upon heating while melting the confined crystal. We discuss this collective molecular realignment in terms of a competition between weak planar anchoring at the p-Al2O3/12CB interface and a preferred texture typical of the crystallization of rodlike molecules in nanochannels (Bridgman growth).

Criticality of an isotropic-to-smectic transition induced by anisotropic quenched disorder

We report combined optical birefringence and neutron scattering measurements on the liquid crystal 12CB nanoconfined in mesoporous silicon layers. This liquid crystal exhibits strong nematic-smectic coupling responsible for a discontinuous isotropic-to-smectic phase transition in the bulk state. Confined in porous silicon, 12CB is subjected to strong anisotropic quenched disorder: a short-ranged smectic state evolves out of a paranematic phase. This transformation appears continuous, losing its bulk first-order character. This contrasts with previously reported observations on liquid crystals under isotropic quenched disorder. In the low temperature phase, both orientational and translational order parameters obey the same power law.

Triple-negative breast cancer: Epidemiology, characteristics, and survival in a Lebanese cohort

e22228

Background: Breast cancer (BC) is the most common malignancy in women in Lebanon. Triple negative (TN) phenotype is known to be associated with an increased likelihood of recurrence and death. The purpose of this study is to determine the incidence, characteristics and survival of TN BC patients in a Medical Oncology department in a University Hospital in Lebanon. Methods: We retrospectively reviewed the pathology of all women with breast cancer that were seen in our institution between 1997 and 2008. TN BC patients (pts) were defined as those that were negative for all 3 receptors (estrogen, progesterone and HER2neu on immunohistochemistry). Pts' characteristics and survival of TN women were analyzed. Results: Of the 1599 breast cancer pts, 155 (9.7%) had a triple negative phenotype. Median age was 52 years. A positive family history of breast/ovarian cancer was found in 15 pts (10%). Pathology studies showed: invasive ductal carcinoma component in 138 pts (89%), pure medullary carcinoma in 7 pts (5%), pure invasive lobular carcinoma in 6 pts (4%), pure mucinous carcinoma in 3 pts (2%) and epidermoid carcinoma in 1 pt (1%). A grade III was found in 98 of specimens (63%). Twenty-six pts (17%) presented with stage I, 73 (47%) with stage II, 37 (24%) with stage III and 19 (12%) with stage IV. Twelve percent had inflammatory breast cancer. After a median follow up of 17 months (mths), 43 pts had relapsed (5 stage I, 18 stage II and 20 stage III). The most common sites of relapse were brain (in 20 % of cases), lungs (in 20% of cases) and bone (in 11% of cases). Five- year disease free survival and 5-year overall survival were respectively 75% and 88% for stage I, 58% and 72% for stage II and 40% and 63% for stage III. Adjuvant therapy was administered to 96% of pts among which a taxane-based regimen was used in 38% of cases . Median survival for stage IV was 19 mths with a first line taxane-based regimen used in 50% of cases. Conclusions: The incidence of TN BC in Lebanon is similar to that described in the literature. It has an aggressive course. Focus on understanding the biology of this particular BC subtype is essential for determining targets for future therapeutic options.

No significant financial relationships to disclose.

[Synchronous sigmoid colon and breast cancers in man]

We report the case of 72-year-old man with sigmoid colon cancer associated with synchronous right breast cancer. However, in the present case, we found breast cancer insidiously at physical exam. The patient died after six months after the dissemination of the breast cancer.

Preliminary results of phase II study of irinotecan and capecitabine combination as first line chemotherapy for advanced and metastatic gastric cancer

14030

Background: Chemotherapy has a proven palliative role in advanced gastric cancer. The most widely investigated single-agent chemotherapy is 5-fluorouracil with partial response rates up to 20%. Single-agent irinotecan achieved response rates of 18%-23%. We investigated the combination Irinotecan plus Capecitabine for previously untreated locally advanced or metastatic gastric cancer. Methods: We conducted a phase II study with the combination of Irinotecan 80 mg/m2 on day 1, 8, and 15, and capecitabine 625 mg/m2 twice daily on days 1 to 14 repeated every 4 weeks. Patients were evaluated every second cycle. Previous chemotherapy for metastatic disease was not allowed. Patients must have measurable disease, ECOG PS < 2, life expectancy > 2 months, adequate hematological, liver and renal functions. Response was evaluated according to RECIST and toxicities according to NCI common toxicity criteria 3.0. Results: Between February 2002 and December 2005 31 patients were enrolled (20 male and 11 female). The median age was 57 years [range 37–74 years]. 142 cycles were administered with a median of 4.6 cycles per patient [range 1–10 cycles]. 29 patients were evaluable for response, and two are on ongoing treatment. Partial response rate was 38.5% . 9 patients (29%) had stable disease. Overall tumor control rate was 67.5%. Median time to progression and overall survival were 5.8 months [range- 1–16] and 10.58 months [range- 1–21] respectively. There was no grade III-IV reported toxicity including no hand and foot syndrome. Conclusions: Irinotecan and capecitabine in combination show an interesting tumor control rate (67.5%) with extremely well tolerated toxicity in patients with extensive gastric cancer.

No significant financial relationships to disclose.

Preliminary results of second-line chemotherapy with vinorelbine and gemcitabine after docetaxel and carboplatin failure in advanced non small cell lung cancer (NSCLC)

17130

Background: To evaluate the efficacy and safety of a doublet platinum-free therapy based on Vinorelbine and Gemcitabine in the salvage treatment of patients with advanced NSCLC, previously treated with Carboplatin and Docetaxel. Methods: We conducted a phase II study with the combination of vinorelbine 30 mg/m2 and gemcitabine 1000 mg/m2 d1 d8 / 3w. Eligible were patients with histologically proven advanced or metastatic NSCLC who were refractory or progressed after first-line chemotherapy combining Docetaxel and Carboplatin. Results of this first-line therapy were already reported (Proc. Am. Soc. Clin. Oncol. 2005, abstr 7330). Patients must have measurable disease, PS ≤ 2, life-expectancy ≥ 3 months, adequate hematologic, liver and renal functions. Response to therapy was evaluated according to RECIST guidelines. Toxicities were assessed according to the national cancer institute (NCI) common toxicity criteria 3.0. Results: From August 2004 to September 2005, 28 patients were enrolled. Median age was 63 years (range, 44 to 77) with 18 males and 10 females. A total of 109 cycles were delivered with a median of 4 cycles per patient (range, 1 to 9). Mean metastatic sites were lymph nodes in 9 pts, liver in 6 pts and pleura in 5 pts. 26 patients were evaluable for response (1 patient too early and 1 pt lost of follow-up). 6 patients responded partially (23%), one of them was initially resistant to the first-line therapy. 11 patients had stable disease (42%). Mean objective response duration was 7 months (range, 5 to 10+). Main toxicities (grade 3/4) were: anemia in 4 patients, neutropenia in 7 patients, leucopenia in 8 patients and lymphopenia in 4 patients. Neutropenic fever was encountered in only one patient. Non-hematological toxicities grade 3/4 were universally absent. No dose reduction or treatment delay related to toxicity was necessary. Conclusion: The study is still ongoing and more patients are expected to define time to progression and survival. However, these preliminary results were encouraging with low toxicity profile.

No significant financial relationships to disclose.

Capecitabine and irinotecan in elderly patients with advanced or metastatic gastro-intestinal tumors

18619

Background: Capecitabine and Irinotecan exhibit single-agent activity in gastro-intestinal tumors. Their combination seems safe and effective. Adult patients with advanced or metastatic gastric or colorectal cancers were enrolled separately in 2 phase II trials dealing with the combination of both drugs. The aim of this study was to evaluate retrospectively the toxicities and the safety profile of this combination in elderly patients (≥ 65 years) as first line therapy for advanced or metastatic gastro-intestinal cancers. Methods: Patients with advanced or metastatic adenocarcinomas of the colon or the stomach aged 65 years or more were treated with the combination of: Irinotecan 80 mg/m2 IV d1,8,15, and Capecitabine 1250 mg/m2 orally d 1–14, Q 4w. Toxicities were graded according to the NCI common toxicities criteria version 3. Results: 24 naïve-chemotherapy patients were included. Median age was 68 years (extremes 65 to 88). Primary tumor was stomach, colon, and rectum in 13, 9, and 2 cases respectively. Frequent sites of metastases were liver (18), lymph nodes (8), peritoneum (7), and lung (5). They received 113 cycles with median number 4.7/patient, and extremes 1 to 14. Serious toxicities graded as IV were universally absent. Grade III anemia, diarrhea, and vomiting were encountered in 1, 1, and 2 patients respectively. Grade II anemia, leucopenia, diarrhea, alopecia, fatigue, and vomiting were recorded in 5, 2, 4, 2, 2, and 6 patients respectively. Hand-foot syndrome was observed as only grade I in 2 patients. There was no febrile neutropenia. In the other hand, objective response was encountered in 9 patients (37.5%), with median response duration of 6 months (extremes 1 to 15). After a median follow-up of 36 months, 19 patients died from progression of their disease with mean overall survival of 5.5 months (extremes 1 to 28). Conclusion: The combination of Irinotecan and Capecitabine according to our schedule revealed an excellent safety profile with easily manageable toxicities. This schedule is highly suitable for elderly patients.

No significant financial relationships to disclose.

Gemcitabine and pegylated liposomal doxorubicin as salvage therapy in metastatic breast cancer (MBC)

10645

Background: Doxorubicin and Taxanes are the most used drugs in front-line therapy for MBC. Patients with progressive disease refractory to these drugs are candidate to different salvage regimens. We investigated the combination of gemcitabine and pegylated liposomal doxorubicin as salvage option for these patients. Methods: This phase II study included gemcitabine (Gemzar) 1000 mg/m2 day 1, day 8 and pegylated liposomal doxorubicin (Caelyx) 25 mg/ m2 day 1 every 21 days. Inclusion criteria included measurable disease, performance status <2 according to the Zubrod scale, and no prior Gemzar or Caelyx treatment. Patients had to have one line of chemotherapy for metastatic disease. Responses were evaluated according to the RECIST criteria. Study Objectives were response rate, time to progression, and toxicity profile. Results: Between March 2003 and September 2005, 30 patients were enrolled. Mean age was 54 years [32–72]. 22 patients had two or more metastatic sites. Mean metastatic sites were liver (17), bone (12), lung (10) and pleura (5). 26 patients have had prior taxane treatment, and 21 prior anthracyclines. 144 cycles were delivered with a median of 6 per patient. There were 13 partial response, 11 stable disease, 5 progression and 1 unknown. Overall response rate was 43% with median response duration of 7 months (4–20+). 12 among the 13 objective responses were noted at visceral sites. During follow-up, 14 patients died. Median Survival time was 7 months. Median Time to progression was 7 months [0.5–20+]. The most encountered grade 3 or 4 toxicities were anemia in 5 pts, thrombopenia in one pt, neutropenia in 7 pts, neutropenic fever in 2 pts, hand-foot syndrome in 4 pts and stomatitis in 3 pts. No cardiotoxicity was noted. Conclusion: Salvage therapy for MBC could be successfully achieved by the combination of Gemcitabine and Pegylated liposomal doxorubicin (43% OR) according to our schedule. The tolerability was also acceptable. This schedule warrants further investigation.

No significant financial relationships to disclose.

[Mesothelioma--asbestos in Lebanon: a problem to be considered]

To estimate the incidence of pleural mesothelioma and its relationship with the occupational and environmental exposure to asbestos in Chekka region. Between 1991 and 2000, 22 cases of malignant mesothelioma were diagnosed at Hôtel-Dieu de France Hospital. Eighteen cases were epidemiologically investigated. Fifteen among these 18 patients (83%) had a positive exposure history: exposure was occupational in 11 cases and environmental in 4 cases. The tumor was attributable to Eternit Company in 12 cases among the exposed 15 (80%). These 12 cases were secondary to occupational exposures in 8 and to environmental exposure in 4 cases. Mean latency period between exposition and diagnosis was 29 years. Fifteen patients died from the progression of their disease after a median survival of 8 months. The relationship between pleural mesothelioma and Eternit Company with the related occupational and environmental risk in Chekka region is obvious. The assessment of the incidence needs a national cancer registry. Despite the protective measures taken by the government since 1996, an increase in the incidence is suspected in the coming ten years because of the long latency period of the disease.

[Castelman's disease. Report of two cases with review of the literature]

Castelman's disease, an unusual condition of unknown cause, consisting of a massive proliferation of lymphoid tissue. Three histologic variants (hyaline vascular, plasma-cell, and mixed) and two clinical types (localized and multicentric) of Castelman's disease have been described. Localized disease can be cured with surgery or radiotherapy, but complete remission in patients with multicentric disease have been achieved only with prednisone or chemotherapy given at the time of diagnosis. The aim of this study is to report two cases of retroperitoneal Castelman's disease with review of the literature. The first patient, of 36 years old, presented for abdominal pain with anorexia and weight loss. The abdomino-pelvic CT scan showed a 6 cm retroperitoneal mass. The biopsy of this lesion suspected a lymphoproliferative disease. At laparotomy total excision of mass was made and the final histology revealed a hyalino-vascular type of Castelman's disease. The second patient, of 26 years old, presented for left lombar pain with weight loss. The abdominopelvic CT Scan showed a 6.5 cm retroperitoneal mass. The biopsy of this lesion showed a Castelman's disease. At laparotomy total excision of mass was made and the final histology confirmed a hyalino-vascular type of Castelman's disease.

[Necrotizing fasciitis in sacrococcygeal pilonidal sinus in a patient with bone marrow aplasia. Treatment by large excision and closing by local flaps]

Pilonidal sinus is a frequent, benign disease with either an acute or a chronic course. The treatment of this common disease is essentially surgical. Necrotizing fasciitis is a rare complication of this disease that can be life-threatening, especially in immunocompromised subjects. The authors report the case of a 35-year-old woman with bone marrow aplasia following chemotherapy for type 2 acute myeloblastic leukaemia, who developed necrotizing fasciitis of a pre-existing sacrococcygeal pilonidal sinus and present a review of the literature.

[Cerebral metastasis disclosing osteosarcoma. Apropos of a case]

Brain metastasis from osteosarcoma is a rare entity. Almost 20 cases have been reported in the literature. We report an illustrative case of a 15 years old boy presenting with isolated brain metastase revealing a fibular osteosarcoma. Diagnostic methods and treatment modalities are discussed.

[Radiation-induced esophageal cancer. Presentation of a case and review of the literature]

Esophageal cancer induced by radiation is uncommon. Irradiation of the head, the neck, the chest and the abdomen may cause an esophageal cancer several years later. Therefore, regular gastroscopy and biopsy of esophageal mucosa are strongly recommended in symptomatic patients. Surgery combined or not with radiotherapy seems to be the most effective treatment for this kind of cancer. We report a case of squamous cell carcinoma of the esophagus diagnosed 13 years after chemotherapy and radiotherapy for Hodgkin disease stade IIIb.

[Gastric metastases of breast cancer]

Breast cancer is the most frequently encountered cancer in women and the first cause of death in the female population. Metastasis may occur ubiquitously depending on the histological type and the presence or absence of oestroprogesterone receptors. We report three cases with gastric metastasis. Signs of gastric involvement are often non-specific and should not be mistaken for simple side reactions to treatment. Hormone chemotherapy is indicated in most situations but surgery may be needed. It should be noted that gastrointestinal metastasis predominates in lobular breast cancers positive for progesterone receptors.

Phase I trial of Idarubicin (4-demethoxydaunorubicin) in adult acute leukemia

Idarubicin (IDR) is a new analog of Daunorubicin (DNR) selected for clinical trials because of its outstanding activity in experimental leukemias of mice and in several experimental models when compared to DNR and Doxorubicin. This Phase I trial was designed to determine the maximal tolerated dose in adult patients with acute leukemia refractory to prior treatment, using intravenously (I.V.) daily treatments for 5 consecutive days. Eleven patients were entered in this study. The initial dose of IDR was 4 mg/m2/d X 5 I.V. The highest dose given was 8 mg/m2/d X 5 I.V. Dose limiting toxicity were gastrointestinal side effects at the 8 mg/m2/d X 5 level (mucositis-diarrhea). Antileukemic activity has been detected in acute non-lymphoblastic leukemia not pretreated with anthracyclines. For Phase II adult leukemia studies using this schedule, it is recommended that the IDR dose should be 7 mg/m2/d.

[Digestive lymphosarcomas. Apropos of 30 cases]

30 cases of digestive non-Hodgkin lymphomas are studied. Localization of the tumor was gastric in 14 cases, ileocoecal in 9 and in the small bowel in 7. Patients with gastric involvement are older (median 48 1/2 years) than those in the other groups (median 26 years). Management included maximal surgery followed by intensive chemotherapy with adriamycin, VM 26 and cyclophosphamide. This protocol gives excellent results: 85% lasting complete remissions with a median follow-up of 30 months and a maximal follow-up of 102 months. Failures occur only in the lymphoblastic cases which require a more intensive chemotherapy.