Intervening in the ß-barrel structure of lipid binding proteins: consequences on folding, ligand-binding and aggregation propensity.

Natural ß-folds manage to fold up successfully. By contrast, attempts to dissect fragments or peptides from well folded ß-sheet proteins have met with insurmountable difficulties. Here we briefly review selected successful cases of intervention on the well-known scaffold of intestinal fatty acid binding protein (IFABP). Lessons from these examples might set guidelines along the design of proteins belonging to this class. Impact of modifications on topology, binding and aggregation is highlighted. With the aid of abridged variants of IFABP we focus on key structural features responsible for the assembly into oligomeric forms or aggregates.

Structural glance into a novel anti-staphylococcal peptide.

Novel antimicrobial peptides are valuable molecules for developing anti-infective drugs to counteract the contemporary spread of microbial drug-resistance. Here we focus on a novel peptide (RKWVWWRNR-NH2) derived from the fragment 107-115 of the human lysozyme that displays a 20-fold increase in anti-staphylococcal activity. The conformational analysis of this peptide and its interaction with model lipidic phases-as assayed by circular dichroism and fluorescence spectroscopy-show a noteworthy spectral change, which might be related to its anti-staphylococcal activity. The secondary structure of peptide [K(108)W(111)] 107-115 hLz was dramatically affected through a single substitution at position 111 (Ala by Trp). Therefore, this conformational change might improve the interaction of the novel peptide with the bacterial plasma membrane. These results highlight the role of peptide secondary structure and the distribution of polar/nonpolar residues for the effective interaction of this peptide with the bacterial plasma membrane, a key step for triggering its lethal effect. This knowledge may contribute to the rational design of a new generation of antimicrobial peptides with increased efficacy developed from natural sources by simple screening tools.

Performance of alginate films for retention of L-(+)-ascorbic acid.

In view of acting as controlled delivery systems for nutritional supplementation, therapy or antioxidant activity at interfaces, alginate films of different copolymer composition and glycerol plasticizer levels were developed in the presence of Ca(2+) for achieving higher stability of L-(+)-ascorbic acid (AA). The ability of the alginate network to preserve AA from hydrolysis, tested by storage under vacuum at 25 °C, only decreased with the relative humidity (RH) increase when alginates were mainly constituted by guluronic-guluronic acid blocks (GG), whereas also decreased with the glycerol level increase when mannuronic-mannuronic acid (MM) and/or alternating guluronic-mannuronic (GM+MG) flexible blocks were present in higher proportions. This result could be probably related to the lower capability of the latter alginate block compositions to immobilize water in the network as they are not able to constitute Ca(2+) mediated junction zones where water molecules are highly retained. Films also studied under air storage showed that even at less favorable conditions of RH and glycerol levels, both GG and GM+MG enriched alginate networks in general preserved AA from oxidation. It also demonstrated that hydrolysis is the principal way by which AA is lost when supported in films.

Semiología de la PET/TAC con 18F-FDG / No disponible

No disponible

[Utility of myocardial perfusion SPECT for evaluation of patients from Chest Pain Unit]. / Análisis y utilidad de la tomografía de emisión de fotón único de perfusión miocárdica en la evaluación de pacientes de la Unidad de dolor torácico.

UNLABELLED: The Chest Pain Units (CPU) are currently the best solution to improve management of patients with acute chest pain in the Emergency Room thanks to the use of reliable ischemia diagnostic detection tests and early treatment. OBJECTIVE: To assess the value of myocardial perfusion SPECT (MPS) in the CPU in order to treat acute coronary syndromes (ACS) early and discharge patients with low risk of coronary artery disease (CAD) who can be treated as outpatients. MATERIAL AND METHODS: We studied 629 patients from January 2003 to September 2005 with acute chest pain suggestive of angina, normal cardiac enzymes and normal or non-diagnostic ECG who had been referred to Nuclear Medicine for evaluation with a stress test for ischemia: 32 p treadmill stress testing and 597 p MPS (525 p exercise-rest and 72 p pharmacologic stress test). We compared the results with catheterization and clinical follow up for a 6-months period, evaluating new coronary events. RESULTS: 76 % of MPS were normal and 24 % pathological. Only 1.5 % of the patients with normal MPS had CAD or coronary events in the follow-up, increasing to 35.2 % in patients with ischemia. A total of 45 catheterizations were performed, showing CAD 27 (24 with pathological MPS). A total of 2.6 % of the patients had coronary events during follow-up, 75 % of whom had pathological MPS. CONCLUSION: The MPS improves diagnosis of ACS in the CPU, with a very low number of new coronary events at 6 months of the follow-up and permits safe discharge of these patients.

Differential regulation of membrane associated-growth hormone binding protein (MA-GHBP) and growth hormone receptor (GHR) expression by growth hormone (GH) in mouse liver.

Growth hormone (GH) binding to GH receptor (GHR) is the initial step that leads to the physiological functions of the hormone. Proteolytical cleavage of the GHR in humans and rabbits and alternative processing of the GHR transcript in rodents generates circulating growth hormone binding protein (GHBP). Moreover, other GHR truncated forms that result from alternative processing of the GHR mRNA transcript have been described. These GHR short forms are inserted in the plasma membrane but they are unable to transduce the signal. In rodents, membrane associated-GHBP (MA-GHBP), which accounts for a significant proportion of liver GH binding capacity, represents the main GHR short form found in membranes, and may therefore function as a negative form of the receptor. In the present study, GHR and MA-GHBP content in liver were analyzed using mutant and transgenic mice expressing different concentrations of growth hormone to evaluate the correlation between GH levels, body weight (BW), GHR and MA-GHBP expression. It was found that GH deficiency was associated with diminished BW, GHR and MA-GHBP expression, while increased GH concentration led to increased BW, GHR and MA-GHBP expression, but MA-GHBP upregulation was more pronounced than the observed increase in GHR expression. Since GHR and MA-GHBP both contribute to liver GH binding capacity, GH-induced enrichment of the dominant negative form would represent a compensatory mechanism triggered by high levels of the hormone. This attempt to attenuate the effects of supraphysiological concentrations of GH may be critical to reduce or prevent their plausible damaging effects on the organism.

[Iatrogenic lung microembolism detected by 18FDG PET/CT]. / Microembolia pulmonar iatrogénica detectada mediante 18F-FDG PET/TC.

We present the cases of two oncology patients: a male with Hodgkin's disease after completion of chemotherapy, and a woman recently diagnosed of melanoma, who underwent positron emission tomography/computed tomography (PET/CT) with 18F-FDG for therapeutic monitoring and initial staging, respectively. In both cases, hypermetabolic foci of 18F-FDG in lung parenchyma were found, without morphologic abnormalities in CT. These findings would have been consistent with lung pathology in the absence of any anatomic correlation. Combined PET/CT interpretation was of lung microembolisms probably originated at the injection site.

Microembolia pulmonar iatrogénica detectada mediante 18F-FDG PET/TC / Iatrogenic lung microembolism detected by 18FDG PET/CT

Presentamos los casos de dos pacientes oncológicos: varón con enfermedad de Hodgkin tras finalizar tratamiento quimioterápico y mujer recién diagnosticada de melanoma coroideo, a los que se realiza tomografía por emisión de positrones/tomografía computarizada (PET/TC) con 18F-fluorodesoxiglucosa ( 18F-FDG) para monitorización terapéutica y estudio de extensión inicial, respectivamente. En ambos casos se encuentran focos hipermetabólicos de 18F-FDG en parénquima pulmonar, sin concordancia morfológica en la TC. Estos hallazgos hubieran sugerido patología pulmonar en caso de no disponer de estudio anatómico conjunto. La interpretación de la PET/TC fue de microembolismos pulmonares probablemente originados en el punto de inyección

We present the cases of two oncology patients: a male with Hodgkin's disease after completion of chemotherapy, and a woman recently diagnosed of melanoma, who underwent positron emission tomography/computed tomography (PET/CT) with 18F-FDG for therapeutic monitoring and initial staging, respectively. In both cases, hypermetabolic foci of 18F-FDG in lung parenchyma were found, without morphologic abnormalities in CT. These findings would have been consistent with lung pathology in the absence of any anatomic correlation. Combined PET/CT interpretation was of lung microembolisms probably originated at the injection site

Quiste del colédoco: diagnóstico mediante gammagrafía hepatobiliar / Choledochal cyst: diagnosis by hepatobiliary scintigraphy

No disponible

[Renal angiomyolipoma and fever: assessment with isotopic renogram and 67Ga scintigraphy]. / Angiomiolipoma renal y fiebre: valoración mediante renograma isotópico y gammagrafía con 67Ga.

A 26 year-old woman with tuberous sclerosis who came to the Emergency Department with high fever, bilious vomit, right hemiabdomen pain and syncope during 2 weeks. Laboratory analyses show hemoglobin 6.7 g/dl, creatinine 1.5 mg/dl and leukocytes 30,000. Abdominal CT is performed because of suspicion of active bleeding in right hemiabdomen, following rupture of right angiomyolipoma, treated by selective arterial embolization. She was referred to the Nuclear Medicine Department to perform a 67Gallium scintigraphy for the detection of infection, and static and dynamic renal scintigraphy for evaluation of the renal morphology and function.

Angiomiolipoma renal y fiebre: valoración mediante renograma isotópico y gammagrafía con 67Ga / Renal angiomyolipoma and fever: assessment with isotopic renogram and 67Ga scintigraphy

Mujer de 26 años con esclerosis tuberosa, que acude a urgencias por cuadro de dos semanas de evolución de fiebre, vómitos biliosos, dolor en flanco derecho y síncope de segundos de duración. En analítica se refleja hemoglobina de 6,7 g/dl, creatinina de 1,5 mg/dl y leucocitosis (30.000/μl). Se realiza TC abdominal por sospecha de sangrado activo, llegándose al diágnostico de rotura de angiomiolipoma renal derecho, que se trata mediante embolización arterial selectiva. Se remite al servicio de Medicina Nuclear para determinar mediante Gammagrafía con 67Ga posible origen de foco infeccioso no puesto en evidencia por otras técnicas diagnósticas, así como Gammagrafía renal y Renograma isotópico para evaluar la morfología renal y el grado de funcionalidad

A 26 year-old woman with tuberous sclerosis who came to the Emergency Department with high fever, bilious vomit, right hemiabdomen pain and syncope during 2 weeks. Laboratory analyses show hemoglobin 6.7 g/dl, creatinine 1.5 mg/dl and leukocytes 30,000. Abdominal CT is performed because of suspicion of active bleeding in right hemiabdomen, following rupture of right angiomyolipoma, treated by selective arterial embolization. She was referred to the Nuclear Medicine Department to perform a 67Gallium scintigraphy for the detection of infection, and static and dynamic renal scintigraphy for evaluation of the renal morphology and function

[Follow-up of children and young adults with differentiated thyroid cancer treated with radioiodine]. / Seguimiento de niños y jóvenes adultos con cáncer diferenciado de tiroides (CDT) tratados con radioyodo.

This is a retrospective study carried out in a group of 30 patients with differentiated thyroid cancer (age at diagnosis equal to or less than twenty years old). The aim of the study is to evaluate outcome after 131I therapy. Patients were classified into three groups on the basis of initial surgery, pathology and scintigraphic results: group I (thyroid extent), group II (locoregional extent), and group III (distant metastatic disease). Clinical parameters, 131I scans, serum thyroglobulin determinations and 131I therapeutic administered doses were evaluated in the follow-up. Some other complementary techniques such as chest X-ray and pulmonary function tests are also described. Scintigraphic absence of thyroid tissue has been observed in 83% of the cases; high thyroglobulin level is still detectable in 34% of the patients as a single evidence of disease, and 21% remain without any abnormal clinical, scintigraphic or analytical findings. Total doses administered have increased in groups I, II and III respectively, and have also been inversely proportional to the extension of lymph node surgery. At present, all the patients are alive and in good general condition. According to the results obtained, we conclude that children and young adults with DTC should undergo periodical 131I therapeutic doses in case of positive scans (once total thyroidectomy has been realized, with or without lymph node resection depending on the extension of disease). In our experience, the use of radioiodine is effective and safe in the follow-up of children and youngs with DTC.

Seguimiento de niños y jóvenes adultos con cáncer diferenciadode tiroides (CDT) tratados con radioyodo / Follow-up of children and young adults with differentiated thyroid cancer treated with radioiodine

Este es un estudio retrospectivo realizado en un grupo de treinta pacientes con carcinoma diferenciado de tiroides (edad al dignóstico igual o menor a veinte años), que tiene como objetivo valorar la respuesta al tratamiento con radioyodo. Los pacientes fueron clasificados en tres grupos según los resultados quirúrgicos, anatomopatológicos y gammagráficos iniciales: grupo I (enfermedad limitada al tiroides), grupo II (enfermedad locorregional), grupo III (afectación metastásica a distancia). En el seguimiento se evaluaron parámetros clínicos, resultados de rastreos gammagráficos con Iodo-131, determinaciones de tiroglobulina sérica y dosis terapeúticas de radioyodo administradas. También se describen otras técnicas complementarias como la radiología de tórax y las pruebas de función respiratoria. Hemos observado una negativización gammagráfica en el 83 por ciento de los casos; un 34 por ciento presenta niveles de tiroglobulina elevados como único hallazgo sugestivo de existencia de enfermedad y un 21 por ciento no presenta hallazgos clínicos, analíticos o gammagráficos patológicos. Las dosis totales de radioyodo administradas han sido crecientes en los grupos I, II y III respectivamente, e inversamente proporcionales a la extensión de la limpieza ganglionar efectuada. En la actualidad todos los pacientes están vivos y presentan un buen estado general.De acuerdo con los resultados obtenidos, concluímos que el manejo adecuado del CDT en este grupo de edad debe incluir rastreos gammagráficos periódicos con 131I y dosis terapeúticas de 131I en caso de rastreos positivos (una vez realizada la tiroidectomía total, con o sin limpieza ganglionar dependiendo de la extensión de la enfermedad). Según nuestra experiencia, el empleo de radioiodo es eficaz y seguro en el seguimiento de niños y jóvenes con CDT. (AU)

Ovine placental lactogen and ovine prolactin: partial proteolysis and conformational stability.

The high-resolution structure of ovine placental lactogen (oPL) and ovine prolactin (oPRL), not yet established in detail, was probed by limited proteolysis with the Glu-specific protease from Staphylococcus aureus V8. While in hGH there were no cleavage sites inside of any of the four alpha-helices, the analysis of the fragments obtained after partial proteolysis of oPL showed a site of cleavage at the putative third helix, suggesting that this helix is partially unwound at this point. The partial proteolysis of the rest of the molecule was compatible with a similar folding pattern for oPL, hGH and pGH, on the basis of the crystal structure of these last hormones. In the case of oPRL, proteolytic cleavage occurred at Glu residues which would be located at the end of the first helix and the beginning of the second in the hGH folding model, suggesting that these helices are shorter in oPRL than in hGH. In order to gain further insight on the folding of these molecules, circular dichroism and intrinsic fluorescence measurements were used to examine the effect of denaturing conditions on oPL and oPRL. After exposure to 6 M guanidine the unfolding of both proteins was completely reversed upon elimination of the denaturing agent. In contrast, exposure to pH 3.0 caused an irreversible decrease in the alpha-helical content in both hormones, most striking for oPL, indicating that this hormone is less stable than oPRL or hGH.

The diagnostic value of Tc-99m human polyclonal immunoglobulin imaging compared to Tc-99m HMPAO labeled leukocytes in inflammatory bowel disease.

The aim of this study was to establish the usefulness of Tc-99m human polyclonal immunoglobulin (HIG) imaging in a group of patients who were suspected of having inflammatory bowel disease (IBD). The authors performed 30 scans (15 with Tc-99m HMPAO leukocytes and 15 with Tc-99m HIG) on 15 patients with IBD. Ten patients had Crohn's disease and five had ulcerative colitis. The sensitivity of Tc-99m HIG scintigraphy for detecting IBD was 33%, while the sensitivity of Tc-99m HMPAO leukocyte imaging was 100%. The Tc-99m HMPAO leukocyte imaging also detected a larger number of affected segments and provided better image quality of the extent of disease than Tc-99m HIG. On the basis of these results, the authors believe that Tc-99m HIG imaging is not a useful technique in the evaluation of patients with IBD, in the identification of location, or the extension or degree of disease activity.

MCA serum determination in breast carcinoma patients for the diagnosis of bone metastases.

Serum MCA levels were determined in 173 consecutive patients with breast cancer in order to assess the clinical utility of MCA for the detection of bone metastases. Bone pathology was diagnosed by scintigraphy, radiology and clinical follow-up. Metastases were found in 37 patients, benign lesions in 25, and in 111 no bone lesions were found. Eighteen of the 173 bone scans were considered indeterminate for metastases. Based on the receiver-operating characteristic curves (ROC) analysis, the cut-off level for MCA was set at 20 U/ml. Only in 4 of the 37 patients with bone metastases MCA was below 20 U/ml. All 4 patients had completed their chemotherapy course within six months before MCA determination. Only in 6 patients of the 136 without bone metastases MCA levels were above 20 U/ml. Of the 18 patients with indeterminate bone scans, 15 had benign lesions and all of them had MCA levels below 20 U/ml. MCA determination is a sensitive method for the detection of bone metastases in breast carcinoma. We encourage the use of this procedure for the selection of high-risk groups or as a complementary method for the interpretation of bone scintigraphy.