Ion microscopy based on laser-cooled cesium atoms.

We demonstrate a prototype of a Focused Ion Beam machine based on the ionization of a laser-cooled cesium beam and adapted for imaging and modifying different surfaces in the few-tens nanometer range. Efficient atomic ionization is obtained by laser promoting ground-state atoms into a target excited Rydberg state, then field-ionizing them in an electric field gradient. The method allows obtaining ion currents up to 130pA. Comparison with the standard direct photo-ionization of the atomic beam shows, in our conditions, a 40-times larger ion yield. Preliminary imaging results at ion energies in the 1-5keV range are obtained with a resolution around 40nm, in the present version of the prototype. Our ion beam is expected to be extremely monochromatic, with an energy spread of the order of the eV, offering great prospects for lithography, imaging and surface analysis.

Expression and characterization of Escherichia coli derived hepatitis C virus ARFP/F protein.

Genome of the hepatitis C virus (HCV) contains a long open reading frame encoding a polyprotein that is cleaved into 10 proteins. Recently, a novel, so called "ARFP/F", or "core+1", protein, which is expressed through a ribosomal frame shift within the capsid-coding sequence, has been described. Herein, to produce and characterize a recombinant form of this protein, the DNA sequence corresponding to the ARFP/F protein (amino acid 11-161) was amplified using a frame-shifted forward primer exploiting the capsid sequence of the 1b-subtype as a template. The amplicon was cloned into the pET-24a vector and expressed in different Escherichia coli strains. The expressed protein (mostly as insoluble inclusion bodies) was purified under denaturing conditions on a nickel-nitrilotriacetic acid (Ni-NTA) affinity column in a single step with a yield of 5 mg/L of culture media. After refolding steps, characterization of expressed ARFP/F was performed by SDS-PAGE and Western blot assay using specific antibodies. Antigenic properties of the protein were verified by ELISA using HCV-infected human sera and by its ability for a strong and specific interaction with sera of mice immunized with the peptide encoding a dominant ARFP/F B-cell epitope. The antigenicity plot revealed 3 major antigenic domains in the first half of the ARFP/F sequence. Immunization of BALB/c mice with the ARFP/F protein elicited high titers of IgG indicating the relevance of produced protein for induction of a humoral response. In conclusion, possibility of ARFP/F expression with a high yield and immunogenic potency of this protein in a mouse model have been demonstrated.

Advantage of using a home-made ELISA kit for detection of Helicobacter pylori infection over commercially imported kits.

PURPOSE: To evaluate a home-made ELISA kit for detection of Helicobacter pylori (Hp) infection and comparison of its immunologic criteria with those of foreign commercial kits. METHODS: A home-made IgG ELISA kit was developed using soluble antigenic fractions of Hp proteins. Confirmed sera were tested and serological criteria were evaluated through assessment of 199 serum samples. RESULTS: The accuracy, sensitivity and specificity values of home-made kit were 92, 92 and 90.4%, respectively. These immunologic criteria for Trinity kit were 95.2, 95.2 and 95% in comparison with IBL kit (91.3, 92.2 and 88.5%), BIOHIT kit (72.4, 41.6 and 94.1%) and HelicoBlot2.1 (94.2, 93.4 and 100%). Kappa agreement assessment demonstrated that two of the imported ELISA kits had fair to moderate agreement with the home-made kit while the other one had a poor agreement value. CONCLUSIONS: Apart from comparable values between the home-made kit and the most efficient imported kit (Trinity) there was significant cost benefit. Therefore, we recommend the home-made kit as a suitable substitution for detection of Hp infection in the Iranian population.

Comparative study of chemoradiation and neoadjuvant chemotherapy effects before radical hysterectomy in stage IB-IIB bulky cervical cancer and with tumor diameter greater than 4 cm.

Tumor size seems to be a determinant in the prognosis of early cervical cancer. Patients with tumor greater than 4 cm (bulky) in diameter have worse outcome. The purpose of this study was to compare the efficacy of preoperative combined chemoradiation and neoadjuvant chemotherapy (NAIC) programs followed by radical hysterectomy in stage IB-IIB bulky cervical cancer. From September 1999 to April 2002, 60 patients with stage IB-IIB bulky cervical cancer were treated with preoperative external-beam radiotherapy to 45 Gy plus weekly cisplatin 50 mg/m2 or preoperative NAIC by cisplatin 50 mg/m2 and vincristin 1 mg/m2 every 7-10 days, for three courses. Surgery was performed 4-6 weeks after the completion of the preoperative treatment. There were no significant difference between age, stage, tumor size, and histopathologic type in two groups (P > 0.05). Toxicity associated with two treatment methods was usually mild. In chemoradiation group, two patients developed vesicovaginal fistula, and four patients developed long-term hydronephrosis that needed urethral stenting. Before surgery, complete and partial clinical response had no significant difference between two groups (P > 0.05). After surgery, lymph node and parametrial involvement had no significant difference between two groups (P > 0.05). In NAIC group, more patients had significantly residual tumor (P = 0.012), but residual tumor size had no significant difference between two groups (P > 0.05). Pathologic complete response was significantly higher in chemoradiation group (P = 0.004). According to the result of this study, it seems that NAIC and chemoradiation had similar effects in survival prognostic factors.