Hydrodynamic and Electrophoretic Properties of Trastuzumab/HER2 Extracellular Domain Complexes as Revealed by Experimental Techniques and Computational Simulations.

The combination of hydrodynamic and electrophoretic experiments and computer simulations is a powerful approach to study the interaction between proteins. In this work, we present hydrodynamic and electrophoretic experiments in an aqueous solution along with molecular dynamics and hydrodynamic modeling to monitor and compute biophysical properties of the interactions between the extracellular domain of the HER2 protein (eHER2) and the monoclonal antibody trastuzumab (TZM). The importance of this system relies on the fact that the overexpression of HER2 protein is related with the poor prognosis breast cancers (HER2++ positives), while the TZM is a monoclonal antibody for the treatment of this cancer. We have found and characterized two different complexes between the TZM and eHER2 proteins (1:1 and 1:2 TZM:eHER2 complexes). The conformational features of these complexes regulate their hydrodynamic and electrostatic properties. Thus, the results indicate a high degree of molecular flexibility in the systems that ultimately leads to higher values of the intrinsic viscosity, as well as lower values of diffusion coefficient than those expected for simple globular proteins. A highly asymmetric charge distribution is detected for the monovalent complex (1:1 complex), which has strong implications in correlations between the experimental electrophoretic mobility and the modeled net charge. In order to understand the dynamics of these systems and the role of the specific domains involved, it is essential to find biophysical correlations between dynamics, macroscopic transport and electrostatic properties. The results should be of general interest for researchers working in this area.

Size and conformational features of ErbB2 and ErbB3 receptors: a TEM and DLS comparative study.

ErbB2 and ErbB3 receptors belong to the epidermal growth factor receptor family. The members of this family are able to form homo- and heterodimers that trigger diverse downstream signalling concerned to multiple cellular events. In the absence of a ligand, ErbB3 adopts a characteristic tethered conformation, which differs from ErbB2 extended conformation. In this work, transmission electron microscopy (TEM) and dynamic light scattering (DLS) have been used to characterize the conformational features and the size of ErBb2 and ErbB3 receptors. Two main objectives are presented. The first one is to evaluate the use of TEM as a tool for structural studies for this family of receptors. The low molecular weight of these proteins represents a challenging purpose for TEM studies. The other one is to search for a relationship between the results obtained by TEM and those obtained for the hydrodynamic size measured by DLS. This comparison has allowed us to identify the conformational differences of the receptors and to anticipate the use of these experimental techniques for the study of the ligand activated heterodimerization, a process related to a significant number of human malignancies.

[Fulminant ischemic gastropathy: the final stage of a difficult-to-diagnose disease]. / Isquemia gástrica fulminante: el estadio final de una enfermedad poco expresiva.

Ischemic gastropathy is highly infrequent in daily medical practice. In the last few years, the number of reported cases has increased. Although the guiding symptom is usually abdominal pain, the clinical spectrum of the disease is highly variable. Early diagnosis and treatment are essential to change the natural history of the disease. We present the case of a 75-year-old man with chronic abdominal pain who developed a fulminant form of necrotizing gastric ischemia and died within less than 24h.

[Adequate rate of response to hepatitis B virus vaccination in patients with inflammatory bowel disease]. / Eficacia de la vacuna contra el virus de la hepatitis B en pacientes con enfermedad inflamatoria intestinal.

BACKGROUND AND OBJECTIVE: Patients with Inflammatory Bowel Disease (IBD) may have an increased risk of developing hepatitis B virus (HB) infection. Invasive procedures such as colonoscopies and surgery might be some of the reasons for this. Moreover, the use of immunosuppressors may reactivate a latent infection. We assessed the immune status among IBD patients receiving HB vaccine and the circumstances that predicted its results. AIMS AND METHODS: Serological markers of B and C hepatitis virus in patients with IBD who were referred for consultation were assessed since 2006. The subsequent determination of antibodies against superficial antigen (HBsAb) could differentiate between responders and non responders to the vaccine and an adequate immunity to HB was defined as higher than 10mUI/ml. RESULTS: One hundred and twenty nine patients were included in our study. Fifty-six (43,4%) patients had received immunosuppressive medication before the first vaccine dose. Notably, 85 (65.9%) patients had inadequate levels of HBsAb: 36 had no detectable levels and 49 had less than 10mUI/ml. Younger patients had a better immunity response than older patients (30.91+/-14.8 vs 39.91+/-14.2) (p<0.001). CONCLUSION: More than half of the patients had a suboptimal serologic response after vaccination. Only the younger group showed a better rate of response. It was not demonstrated whether an additional fourth dose of vaccination or a complete revaccination improved the rate of responders.

[Endoscopic retrograde cholangiopancreatography in patients aged less than 18 years old: our experience]. / Colangiopancreatografía retrógrada endoscópica en pacientes menores de 18 años: nuestra experiencia.

BACKGROUND: There is scant information on the use of endoscopic retrograde cholangiopancreatography (ERCP) in patients under 18. OBJECTIVE: To analyze our experience in all patients under 18 who underwent ERCP. PATIENTS AND METHODS: We performed a retrospective study of all ERCP conducted in patients under 18 between 1993 and 2006. We analyzed indications, endoscopic and radiologic findings, diagnostic and therapeutic success, and complications. RESULTS: We included 31 patients who underwent 36 ERCP in total. The mean age was 9.89 +/- 5 years old. We used general anesthesia in 58.3% (21 patients), with a mean age of 8 +/- 5 years. The most frequent indications were complications after liver transplantation in 33.3% (12 patients), suspicion of biliary obstruction in 27.7% (10 patients), and pancreatitis in 22.2% (8 patients). We achieved cannulation and repletion in the selected duct in 94.4%. The most frequent pathologic findings were changes in the biliary tract after liver transplantation in 25% (9 patients). The results of ERCP were normal in 10 patients (27.7%). Therapeutic maneuvers were indicated in 17 out of the 34 (50%) examinations considered, achieving therapeutic success in 76.47% (13/17). Complications consisted of hemorrhage after simple sphincterotomy in one patient (2.8%) and mild pancreatitis in two patients (5.6%). CONCLUSIONS: We found ERCP to be a safe procedure with a high diagnostic and therapeutic success rate, and a low rate of early complications.

[Usefulness of ultrathin transnasal endoscopy for the placement of nasoenteric feeding tubes]. / Utilidad de la endoscopia ultrafina transnasal en la aplicación de sondas de nutrición enteral.

BACKGROUND: Placement of nasoenteral feeding tubes can require endoscopic support. AIM: To analyze the usefulness of transnasal ultrathin endoscopy in the placement of nasoenteral feeding tubes. PATIENTS AND METHODS: We performed an ambispective study of all patients who underwent nasoenteral feeding (4.9 mm) in 2007. RESULTS: Twenty-six procedures were performed. The mean age of the patients was 69.3+/-13 years. Nasal anesthesia was used in 23 patients (88.4%), and midazolam in 8 (30.8%). No anesthesia was used in 4 patients (15.3%). INDICATIONS: stenotic esophageal lesions (42.3%), distal placement to the pathological alteration (46.1%), and failure of placement through the normal route (11.5%). We placed 13 (50%) nasoduodenal, 7 (29.6%) nasogastric and 6 (23.1%) nasojejunal tubes. The success rate was 100%. The most frequently used calibre was 12 F. There were no complications. CONCLUSIONS: The use of transnasal ultrathin endoscopy in the placement of nasoenteral feeding tubes in our patients was safe, effective and relatively easy.

[Diagnostic value of fecal calprotectin in predicting an abnormal colonoscopy]. / Precisión diagnóstica de la calprotectina fecal para predecir una colonoscopia patológica.

BACKGROUND AND OBJECTIVE: Abdominal pain and diarrhoea are common symptoms in the general population. The colonoscopy is the gold standard method of detecting an organic pathology in the colon. However, it is invasive; it can not be repeated frecuently; it is expensive; and the system is overloaded. Fecal calprotectin (FCP) is a marker that may detect organic pathologies of the colon. The aims of this study were to analyze the usefulness of FCP to predict an abnormal colonoscopy and to correlate the levels of FCP with the degree of activity in inflammatory bowel disease (IBD). PATIENTS AND METHOD: 190 people were included in the study. All of them underwent a colonoscopy and a stool sample. People were divided in: normal colonoscopy: 117 people, and 28 colon adenomas, 20 colorectal cancer (CRC) and 25 IBD. RESULTS: The mean (SD) FCP concentration was 2,171.1 (2,133.6) mg/kgin patients with IBD and 726.6 mg/kg (533) in CRC. Both results were significantly elevated compared with those of healthy controls [114 (113)] mg/kg In patients with IBD, their levels correlated directly with the activity of the inflammation. 217 mg/kg was the best cut-off for discriminating patients with organic colon disorders. The sensibility was 85% and NPV was 93%. NSAIDs use was a clinical variable which was connected with a high FCP concentration in patients with normal colonoscopy. CONCLUSIONS: The higher levels of FCP were found in people with IBD and CRC. The measurement of FCP is a non-invasive, inexpensive, reliable and easily measured test. Among people with abdominal pain and diarrhoea, testing for FCP allows us to select those who must undergo a colonoscopy. NSAIDs can raise the levels of FCP in people with normal colonoscopies.

ERCP in patients 90 years of age and older.

BACKGROUND: Biliary diseases represent particular diagnostic and therapeutic problems in elderly patients. METHODS: Patients 90 years of age or older who underwent ERCP from January 1993 to September 2001 were studied retrospectively. RESULTS: A total of 126 patients underwent 147 ERCP procedures (range 1-5 per patient). Twelve additional ERCPs were performed in 9 of the patients during follow-up because of recurrent symptoms. A total of 159 procedures were, therefore, available for analysis. The most frequent indications were suspicion of bile duct stones (46.8%) and obstructive jaundice (35.7%). Midazolam (95.6%) was used for conscious sedation and hyoscine (74.8%) for duodenal ileus. Patient tolerance of the procedure was good in 92.4% of sessions. Diagnoses included bile duct stones (54%), bile duct dilatation without any apparent obstruction (11.9%), and malignant stenosis (9.5%). Therapeutic procedures were indicated in 95.6% of diagnosed patients and completed in 96.3% of cases. Complications occurred in association with 2.5% of the ERCP procedures; the procedure-related mortality rate was 0.7%. CONCLUSIONS: ERCP in elderly patients is practicable. The complication rate is low, and therapeutic efficacy is good.