Self-assembling processes involved in the molecular beam epitaxy growth of stacked InAs/InP quantum wires

The growth mechanism of stacked InAs/InP(001) quantum wires (QWRs) is studied by combining an atomic-scale cross-sectional scanning tunnelling microscopy analysis with in situ and in real-time stress measurements along the [110] direction (sensitive to stress relaxation during QWR formation). QWRs in stacked layers grow by a non-Stranski-Krastanov (SK) process which involves the production of extra InAs by strain-enhanced As/P exchange and a strong strain driven mass transport. Despite the different growth mechanism of the QWR between the first and following layers of the stack, the QWRs maintain on average the same shape and composition in all the layers of the stack, revealing the high stability of this QWR configuration.

Exciton gas compression and metallic condensation in a single semiconductor quantum wire

We study the metal-insulator transition in individual self-assembled quantum wires and report optical evidence of metallic liquid condensation at low temperatures. First, we observe that the temperature and power dependence of the single nanowire photoluminescence follow the evolution expected for an electron-hole liquid in one dimension. Second, we find novel spectral features that suggest that in this situation the expanding liquid condensate compresses the exciton gas in real space. Finally, we estimate the critical density and critical temperature of the phase transition diagram at n{c} approximately 1 x 10;{5} cm;{-1} and T{c} approximately 35 K, respectively.

Determination of the strain generated in InAs/InP quantum wires: prediction of nucleation sites

The compositional distribution in a self-assembled InAs(P) quantum wire grown by molecular beam epitaxy on an InP(001) substrate has been determined by electron energy loss spectrum imaging. We have determined the strain and stress fields generated in and around this wire capped with a 5 nm InP layer by finite element calculations using as input the compositional map experimentally obtained. Preferential sites for nucleation of wires grown on the surface of this InP capping layer are predicted, based on chemical potential minimization, from the determined strain and stress fields on this surface. The determined preferential sites for wire nucleation agree with their experimentally measured locations. The method used in this paper, which combines electron energy loss spectroscopy, high-resolution Z contrast imaging, and elastic theory finite element calculations, is believed to be a valuable technique of wide applicability for predicting the preferential nucleation sites of epitaxial self-assembled nano-objects.

Changes in Exercise Tolerance, Health Related Quality of Life, and Peripheral Muscle Characteristics of Chronic Obstructive Pulmonary Disease Patients After 6 Weeks' Training

OBJECTIVE

This study was designed to assess changes in skeletal muscle characteristics after 6 weeks' high-intensity physical training of patients with moderate to severe chronic obstructive pulmonary disease (COPD) and to determine how the changes were related to improvements in exercise tolerance and health related quality of life (HRQL).

PATIENTS AND METHODS

Ten patients with a mean (SD) age of 60 (10) years and a forced expiratory volume in 1 second of 32% (9%) were enrolled. The effect of training on the 6-minute walk test, HRQL questionnaires, and skeletal muscles was examined for the 8 patients who completed the program. The structural and chemical characteristics of skeletal muscles before and after training were studied in vastus lateralis muscle biopsies.

RESULTS

Training significantly modified the 6-minute walk test (P<.01), HRQL (P<.05), and citrate synthetase activity (P<.05). Changes in distances walked during the 6-minute walk test were significantly related to changes in the mean area of fibers (r=0.81).

CONCLUSIONS

The results of this study indicate that 6 weeks of high-intensity physical training of COPD patients produces moderate changes in skeletal muscles which could partly explain improvements observed in exercise tolerance after respiratory rehabilitation.

Purification and preliminary characterization of a plasma kallikrein inhibitor isolated from sea hares Aplysia dactylomela Rang, 1828

An inhibitor active against pancreatic trypsin was found in the crude extract from the sea hares Aplysia dactylomelaRang, 1828. A stronger inhibitory activity against human plasma kallikrein was detectable after treating this extract at 60 degrees C, for 30 min. The plasma kallikrein inhibitor (AdKI) purification was achieved by acetone fractionation (80%) v/v, ion-exchange chromatography on Mono Q column and gel filtration chromatography on Superdex 75 column (FPLC system). By the latter a molecular mass of 2900 Da was estimated. The purified inhibitor strongly inhibits human plasma kallikrein with a K(i) value of 2.2 x 10(-10)M, while human plasmin and pancreatic trypsin were inhibited with K(i) values of 1.8 x 10(-9) and 4.7 x 10(-9)M, respectively. Chymotrypsin, pancreatic elastase, pancreatic kallikrein and thrombin are not inhibited. The effect of AdKI on plasma kallikrein was confirmed by the prolongation of activated partial thromboplastin time, using a clotting time assay. The inhibitor did not affect prothrombin time or thrombin time. AdKi is a more specific inhibitor than other serine proteinase inhibitors from marine invertebrates.

Expanded bed adsorption processing of mammalian cell culture fluid: comparison with packed bed affinity chromatography

A comparison between expanded bed adsorption and conventional packed bed Protein A Fast Flow to purify the anti-rHBsAg mAbs from feedstock is presented in this work. Direct capture by STREAMLINE expanded bed adsorption chromatography resulted in 92% product recovery and sevenfold more concentrated product with similar purity levels compared to that obtained by the standard packed method. The process time and buffer consumption were reduced in the expanded bed adsorption method not only with the binding-elution conditions but also with the use of NaOH during the cleaning-in-place step. The latter is the most widely accepted agent in downstream processing, being a cost effective technique that provides not only efficient cleaning but also sanitizes complete column systems and destroys pirogens.

Eosinophilic gastroenteritis: our recent experience: one-year experience of atypical onset of an uncommon disease

Eosinophilic gastroenteritis is an unusual entity that is rarely found in daily clinical practise. Its aetiology is unknown and diagnosis can be made microscopically with evidence of massive eosinophilic infiltration in patients with chronic gastrointestinal symptoms, excluding entities that may cause such findings (parasitic infestation, medical therapy, inflammatory bowel disease, and so on). Allergic processes are usually associated and these normally respond well to steroids. We present our last year's experience of four women with eosinophilic gastroenteritis with an extraordinary atypical clinical onset. Two of the women presented with an acute abdomen and two with isolated colonic involvement. The management of acute abdomen avoiding surgery and a complete response with azathioprine are the outstanding variables that make our recent cases of special interest. Demographic variables were similar to others reported from our medium, with the exception of a higher incidence of women. Our cases suggest the wide spectrum of clinical presentations and show the high suspicion index needed for a diagnosis that is made by pathologists.

Predictive factors for a successful mobilization of peripheral blood CD34+ cells in multiple myeloma

We analyzed the prognostic factors for a successful mobilization and peripheral blood stem cell collection in a series of 57 consecutive patients with multiple myeloma (MM); a new scoring system to predict an adequate mobilization in this subset of patients was also constructed. A total of 221 aphereses were performed in 57 patients with MM. The median time from diagnosis to mobilization was 12 months (range 4-120). Only one line of chemotherapy was administered before mobilization to 36 patients and two or more to 21. The median number of alkylating chemotherapy cycles was 6 (2-33). Two patients were mobilized in complete remission, 32 in partial response, and 23 in stable/progressive disease. Significant adverse prognostic factors for collecting 2.5 x 10(6) CD34+cells/kg or more were: a period of at least 12 months from diagnosis, at least six cycles of alkylating agents, and a plasma cell infiltration of 20% or more prior to mobilization. Patients with three risk factors had a probability of only 0.38 (95% CI 0.3-0.9) for adequate mobilization. Ten patients failed to mobilize; a period from diagnosis of 12 months or more and female sex were unfavorable factors. Patients with two risk factors had a probability of 0.50 (95% CI 0.2-0.8) for failing the mobilization procedure. These findings indicate that MM patients must be mobilized early in the course of the disease, with minimal disease burden before severe hematopoietic progenitor cell injury due to cumulative therapy.

Community respiratory virus infections in patients with hematologic malignancies

BACKGROUND AND OBJECTIVE

The main difficulty of PCR-based clonality studies for B-cell lymphoproliferative disorders (B-LPD) is discrimination between monoclonal and polyclonal PCR products, especially when there is a high background of polyclonal B cells in the tumor sample. Actually, PCR-based methods for clonality assessment require additional analysis of the PCR products in order to discern between monoclonal and polyclonal samples. Heteroduplex analysis represents an attractive approach since it is easy to perform and avoids the use of radioactive substrates or expensive equipment.

DESIGN AND METHODS

We studied the sensitivity and specificity of heteroduplex PCR analysis for monoclonal detection in samples from 90 B-cell non Hodgkin's lymphoma (B-NHL) patients and in 28 individuals without neoplastic B-cell disorders (negative controls). Furthermore, in 42 B-NHL and in the same 28 negative controls, we compared heteroduplex analysis vs the classical PCR technique. We also compared ethidium bromide (EtBr) vs. silver nitrate (AgNO(3)) staining as well as agarose vs. polyacrylamide gel electrophoresis (PAGE).

RESULTS

Using two pair consensus primers sited at VH (FR3 and FR2) and at JH, 91% of B-NHL samples displayed monoclonal products after heteroduplex PCR analysis using PAGE and AgNO(3) staining. Moreover, no polyclonal sample showed a monoclonal PCR product. By contrast, false positive results were obtained when using agarose (5/28) and PAGE without heteroduplex analysis: 2/28 and 8/28 with EtBr and AgNO(3) staining, respectively. In addition, false negative results only appeared with EtBr staining: 13/42 in agarose, 4/42 in PAGE without heteroduplex analysis and 7/42 in PAGE after heteroduplex analysis.

INTERPRETATION AND CONCLUSIONS

We conclude that AgNO(3) stained PAGE after heteroduplex analysis is the most suitable strategy for detecting monoclonal rearrangements in B-NHL samples because it does not produce false-positive results and the risk of false-negative results is very low.

Modulation of hepatic and intestinal glutathione S-transferases and other antioxidant enzymes by dietary lipids in streptozotocin diabetic rats

Antioxidant enzymes in liver and small intestine were investigated using control and streptozotocin diabetic rats fed diets with 5% olive, sunflower or fish oil for five weeks. In liver, Glutathione Peroxidase and Superoxide Dismutase decreased and in intestine Glutathione-S-transferase (GST) increased by diabetes. In isolated jejunum and ileum, this increase in GST activity was due to an increase in GST-alpha and -mu isoenzymes in jejunum and GST-alpha, mu and -pi in ileum. Since GST plays an important role in protecting tissues from oxidative damage, our results highlight the role of the intestine against free radicals in physiological or pathological situations.

Pulmonary enterovirus infections in stem cell transplant recipients

In recent years, it has been recognised that the community respiratory viruses are a frequent cause of upper and lower respiratory tract infections in immunocompromised hosts such as bone marrow transplant recipients. By contrast, infections by non-polio enteroviruses have rarely been reported after stem cell transplantation. We present four cases of acute respiratory illness with enterovirus isolated as the sole pathogen from bronchoalveolar lavage. All four patients developed pneumonia and three died of progressive pneumonia, which reflects the severity of this complication. We conclude that enteroviral pulmonary infections may be a cause of severe pneumonia in immunocompromised hosts.

Moderate hyperhomocysteinemia is a highly prevalent defect in Spanish patients with venous thromboembolic disease

Recent studies suggest that mild hyperhomocysteinemia may be a risk factor for venous thromboembolic disease (VTED). In this work we evaluated the prevalence of moderate hyperhomocysteinemia in patients with VTED in our area. We found hyperhomocysteinemia in 23.4% of 64 patients studied compared with 7.35% of 68 healthy controls (p = 0.014). Our results suggest that moderate hyperhomocysteinemia is one of the most prevalent abnormalities associated with VTED.

A novel cancer vaccine composed of human-recombinant epidermal growth factor linked to a carrier protein: report of a pilot clinical trial

BACKGROUND

There is evidence of a relationship between epidermal growth factor (EGF) and tumor cell proliferation, such as the overexpression of EGF receptor (EGF-R) in different human tumors, which makes this system an interesting target for cancer treatment. Up to now, passive immunotherapy with monoclonal antibodies against the EGF-R has been assayed in clinics. Our approach consists of active immunotherapy with human EGF (hu-EGF). We conducted a pilot clinical trial to define the safety, toxicity and immunogenicity of vaccination with hu-EGF coupled to a carrier protein.

PATIENTS AND METHODS

Ten patients with histologically-proven malignant carcinomas (colon, lung, stomach and prostate) in advanced clinical stages were enrolled. Patients were immunized twice (on days 0 and 15) with hu-EGF linked to either tetanic toxoid (TT, five patients) or P64K Neisseria Meningitidis recombinant protein (P64k, five patients), intradermically, using aluminium hydroxyde as adjuvant.

RESULTS

In both groups 60% of patients developed anti-EGF antibody titers without evidence of toxicity. Secondary reactions were very mild, limited to erythema and itching at the site of injection, which disappeared without medication.

CONCLUSIONS

We conclude that the proposed vaccination with hu-EGF was well tolerated and that antibody titers against self EGF were developed. The results of this trial may be useful in the design of new clinical trials with higher dose immunization protocols and using more effective adjuvants.

Concomitant chronic lymphocytic leukemia and acute myeloid leukemia with an uncommon immunophenotype

We report a case of simultaneous diagnosis of chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML), in which the use of flow cytometry analysis allowed the demonstration of two different cell populations and the study of both immunophenotyping patterns with a large panel of monoclonal antibodies (MoAbs). CLL cells showed a typical immunophenotype with coexpression of B cell markers with CD5, CD23, CD43, and weak surface immunoglobulin light chain restriction expression, whereas the AML population had a very uncommon phenotype with expression of myeloid markers and CD56 and lack of expression of other natural killer (NK) antigens, CD34 and HLA-DR. After chemotherapeutic treatment of AML with two induction courses, the patient achieved complete remission of the AML with persistence of a CD19/CD5 positive population. After consolidation chemotherapy, this latter population was no longer detectable despite the presence of lymphoid nodules in a bone marrow biopsy. Six months after diagnosis, the patient relapsed with AML and died shortly afterwards.

Purification, characterization and immobilization of proteinase inhibitors from Stichodactyla helianthus

Isolation of proteinase inhibitors from the sea anemone Stichodactyla helianthus was achieved by trichloroacetic acid treatment of the aqueous extract followed by affinity chromatography on trypsin-Sepharose and ion-exchange chromatography on CM-cellulose. The average molecular mass of the major inhibitor (ShPI-I) obtained by fast atom bombardment mass spectrometry (FAB-MS) was 6110.6 Da. The amino acid sequence was determined by FAB-MS combined with manual Edman degradation, digestions with endopeptidases and exopeptidases and automatic sequencing. The sequence of ShPI-I (55 amino acids) was compared with those reported in the SwissProt database for several proteinase inhibitors and significant similarity to inhibitors belonging to the Kunitz family was observed. ShPI-I exhibits a broad specificity for serine, cysteine and aspartic proteinases. The dissociation constants of the complexes formed with different enzymes were determined. The affinity-purified fraction (PI) was immobilized on Sepharose and used in the purification of different classes of proteinases.