Multifunctional biosensors based on peptide-polyelectrolyte conjugates.

A novel enzymatic platform for the sensing of H2O2 and glucose that uses L,L-diphenylalanine micro/nanostructures (FF-MNSs) as an enzyme support is shown. This platform is obtained by the self-assembly of poly(allylamine hydrochloride) (PAH), FF-MNSs, and microperoxidase-11 (MP11) anchored onto the peptide matrix, in two different crystal structures of FF-MNSs: hexagonal (P61) and orthorhombic (P22121). The electroactive area of the electrodes increases in the presence of FF-MNSs. We also demonstrate via theoretical calculations that the valence band energy of the orthorhombic structure allows it to be doped, similarly to p-type semiconductors, where PAH acts as a doping agent for the orthorhombic peptide structure, decreasing the band-gap by around 1 eV, which results in a smaller charge transfer resistance. These results are consistent with electrochemical impedance spectroscopy measurements, which further elucidate the role of the band structure of the orthorhombic FF-MNSs in the conductivity and electron transfer rates of the hybrid material. An effective communication between the electrode and the active site of a glucose oxidase enzyme through MP11-protein complexes occurs, paving the way for FF-MNSs in the orthorhombic phase for the future development of bioelectronics sensing devices.

Polycaprolactone fibers with self-assembled peptide micro/nanotubes: a practical route towards enhanced mechanical strength and drug delivery applications.

Peptide-based scaffolds are a frontier research area in materials science with widespread impact in biomedical engineering. In this paper, we describe a hybrid material formulated through the conjugation of electrospun polycaprolactone (PCL) fibers and micro/nanotubes of l,l-diphenylalanine (FF-MNTs). Morphology and crystallinity of the composite matrices are investigated using a wide range of analytical techniques including electron microscopy, thermal analyses, X-ray diffraction and micro-tomography. Peptide assemblies are found to produce deep modifications on the microstructure of PCL fibers, impacting average diameters, crystallinity degree and porous size in the polymer network. These changes are correlated with mechanical properties of the resulting scaffolds, whose strength is found to exhibit a brittle-to-ductile transition upon increasing the amount of FF-MNTs and lead to enhanced Young's moduli of polymer fibers. The PCL/FF-MNTs composites were tested for the drug delivery application of a lipophilic drug, benzocaine. In vitro permeation studies have shown that these polymer/peptide hybrids are able to produce a steady release of benzocaine over periods of up to ∼13 hours, much higher than commercially available gel formulations. Enzymatic tests have shown a significant increment in biodegradation rates in PCL/FF-MNTs hybrids containing higher peptide amounts, which exhibited almost 100% weight loss against only 10% found in pure PCL. Our findings indicate that using PCL/FF-MNTs materials is a simple route towards achieving enhanced mechanical strength of PCL networks that have the ability to promote controlled drug delivery from a completely biodegradable matrix.

Hemobilia in hereditary hemorrhagic telangiectasia: an unusual complication of endoscopic retrograde cholangiopancreatography.

Hepatobiliary manifestations of hereditary hemorrhagic telangiectasia (HHT) are rare, but often involve cholestasis. We report here a case of HHT associated with cholestasis due to common bile duct stenosis. Attempted balloon dilation of the stenosis during endoscopic retrograde cholangiopancreatography (ERCP) resulted in hemobilia. Hemostasis was achieved by adjusting the nasobiliary drain. The aim of this report is to highlight the biliary manifestations of HHT and draw attention to an unusual complication of ERCP in this setting.

[Pancreatic tumors. Therapeutic endoscopy of malignant stenoses of the common bile duct using endoprostheses]. / Tumores do pâncreas. Terapêutica endoscópica das estenoses malignas da via biliar principal com endopróteses.

From September 1987 to April 1994, 144 biliary endoprostheses were introduced (81 male; 63 female; mean age 68.7 years) in patients presenting distal stricture of the common bile duct by pancreatic tumors. 135 plastic (10 and 12 French) and 9 metallic (30 French) prostheses were placed. The most common complication associated with plastic prostheses is clogging (16%); this problem was solved with the use of metallic prosthesis, which is limited by their high cost. The mortality and morbidity are lower and the time hospital discharge is shorter until, than the ones associated with bilio-digestive anastomosis; mean survival is similar with two procedures endoscopy/surgery.

[Advances in the endoscopic therapy of chronic pancreatitis]. / Avanços na terapêutica endoscópica da pancreatite crónica.

Endoscopic interventional techniques have created a wide new perspective for non-surgical treatment of chronic pancreatitis (CP). Surgery and endoscopy differ in their techniques, but are comparable with regard to tactics. The aim of methods in CP is to relieve pain and/or local complications. The preliminary results of endoscopic procedures in CP are promising and the methods appear safe in the hands of experienced endoscopists.

Determination of lomefloxacin in human plasma by solid-phase extraction and high-performance liquid chromatography with UV detection.

A high-performance liquid chromatographic method for the determination of lomefloxacin in human plasma has been developed and validated. A solid-phase extraction procedure was used to isolate lomefloxacin from the biological matrix prior to the quantitative analysis. The compound was separated on a Vydac anion-exchange column using acetonitrile-phosphate buffer (pH 7.0) as the mobile phase and quantified by measuring its UV absorbance at 280 nm. The lower limit of detection for the analyte was 0.05 micrograms ml-1. Enoxacin was used as the internal standard. The calibration graph of the method was linear from 0.1 to 10 micrograms ml-1 of lomefloxacin in human plasma. This procedure is suitable for pharmacological and pharmacokinetic studies of lomefloxacin.

Steroid receptors in Brazilian patients with large bowel cancer.

1. Twenty-two colorectal carcinomas were examined for the presence of estrogen (ER), progesterone (PR), androgen (AR) and glucocorticoid receptors (GR) by a charcoal dextran assay. 2. ER was detected in 4/13 (31%) and 5/9 (56%) of the rectum and colon carcinomas analyzed, and density values ranged from 10 to 14 and from 10 to 27 fm/mg protein, respectively. Normal distal or adjacent mucosa presented similar incidence and ER density values within the tumor ranges. 3. The incidence of PR-positive samples was also higher in colon than in rectal carcinomas (44% vs 23%). Normal mucosa displayed significantly higher PR titers than the corresponding tumor tissue. It seems reasonable to assume that normal colorectal mucosa may be one of the target tissues of progesterone activity. Most tumor biopsies and normal mucosa were completely AR negative, whilst GR was present in a larger fraction (63%) of tumoral specimens, occurring more commonly in colon than in rectum carcinomas. GR incidence tended to be higher in neoplasms than in normal mucosa (54% vs 38% in rectum and 78% vs 56% in colon), suggesting that glucocorticoids may be involved in the control of tumor-cell proliferation. 4. Our findings which indicate low densities of ER, PR, and absence of AR in some large bowel cancers, suggest sex hormone and endocrine independence for those cancers. The role of glucocorticoid receptors in those forms of cancer remains to be elucidated.

Steroid receptors in Brazilian patients with large bowel cancer

1. Twenty-two colorectal carcinomas were examined for the presence of estrogen (ER), progesterone (PR), androgen (AR) and glucocorticoid receptors (GR) by a charcoal dextran assay. 2. ER was detected in 4/13 (31 per cent ) and 5/9 (56 per cent ) of the rectum and colon carcinomas analyzed, and density values ranged from 10 to 14 and from 10 to 27 fm/mg protein, respectively. Normal distal or adjacent mucosa presented similar incidence and ER density values within the tumor ranges. 3. The incidence of PR-positive samples was also higher in colon than in rectal carcinomas (44 per cent vs 23 per cent ). Normal mucosa displayed significantly higher PR titers than the corresponding tumor tissue. It seems reasonable to assume that normal colorectal mucosa may be one of the target tissues of progesterone activity. Most tumor biopsies and normal mucosa were completely AR negative, whilst GR was present in a larger fraction (63 per cent ) of tumoral specimens, occurring more commonly in colon than in rectum carcinomas. GR incidence tended to be higher in neoplasms than in normal mucosa (54 per cent vs 38 per cent in rectum and 78 per cent vs 56 per cent in colon), suggesting that glucocorticoids may be involved in the control of tumor-cell proliferation. 4. Our findings which indicate low densities of ER, PR, and absence of AR in some large bowel cancers, suggest sex hormone and endocrine independence for those cancers. The role of glucocorticoid receptors in those forms of cancer remains to be elucidated

Effects of androgens on proliferation and progesterone receptor levels in T47D human breast cancer cells.

The effects of estradiol (E2), dihydrotestosterone (DHT) and dehydro-3-epiandrosterone (DHEA) on proliferation and progesterone receptor induction were studied in a breast cancer cell line (T47D) expressing estrogen, androgen, and progesterone receptors. A significant enhancement of growth and progesterone receptor expression was observed after treatment with E2 and DHEA, which was antagonized by the antiestrogen tamoxifen and not altered by the antiandrogen flutamide, supporting the involvement of estrogen receptors. When cells were treated with either E2 or DHEA, transforming growth factor-alpha mRNA was induced. DHT treatment did not alter growth but was effective in stimulating androgen receptors and down-regulating progesterone receptors.

Lung beta-adrenoceptors in pulmonary hypertension. A study of biopsy specimens in children with congenital heart disease.

Characteristics of beta-adrenoceptors were analyzed using radioligand-binding techniques with 3H-dihydroalprenolol in lung specimens from 11 children with pulmonary hypertension (median age, three years) undergoing surgical repair of congenital heart defects and four pediatric control subjects (median age, five years) undergoing thoracotomy for removal of neoplasms or cysts. Scatchard analysis of 3H-DHA binding to lung membranes showed similar values of the dissociation constant in both groups (Kd = 0.72 +/- 0.22 nM in patients vs 1.22 +/- 0.22 nM in controls; p = NS). The receptor density was significantly increased in patients in comparison with controls, with respective values of 164 +/- 19 and 95 +/- 13 fmol/mg of protein (p less than 0.025), and correlated directly with mean pulmonary arterial pressure (r = 0.82; p less than 0.0005). No significant relationship was observed between receptor number and pulmonary arterial medial thickness. Thus, the increase in receptor density in these patients may be related to adaptative changes in cells other than vascular smooth muscle.

Occupied and unoccupied type II estrogen binding sites in human breast cancer.

Using a saturation analysis over a wide range of [3H]estradiol at two temperatures 4 and 22 degrees C we have determined unoccupied (4 degrees C) and total (22 degrees C) type II estrogen binding site (EBS) levels in individual cytosols of 100 patients with breast cancer (50 post and 50 premenopausal). Exchange was found to be complete after 18 h at 22 degrees C and receptor degradation was negligible during this treatment. Steroid specificity and affinity determined by Scatchard and Rosenthal plot analysis were not altered at 22 degrees C. Carcinomas presented a higher total type II REBS level as compared unfilled type II binding sites or the classical ER, independently of menopausal status, phase of the menstrual cycle or positivity of ER. On the other hand, unoccupied type II EBS level was strongly correlated to the concentration of type I ER, being higher on the post-menopausal group and older patients.