ABSTRACT
We demonstrate a method for tailoring local mechanical properties near channel surfaces of vascular structural polymers in order to achieve high structural performance in microvascular systems. While synthetic vascularized materials have been created by a variety of manufacturing techniques, unreinforced microchannels act as stress concentrators and lead to the initiation of premature failure. Taking inspiration from biological tissues such as dentin and bone, these mechanical deficiencies can be mitigated by complex hierarchical structural features near to channel surfaces. By employing electrostatic layer-by-layer assembly (ELbL) to deposit films containing halloysite nanotubes onto scaffold surfaces followed by matrix infiltration and scaffold removal, we are able to controllably deposit nanoscale reinforcement onto 200 micron diameter channel surface interiors in microvascular networks. High resolution strain measurements on reinforced networks under load verify that the halloysite reduces strain concentrations and improves mechanical performance.
Subject(s)
Aluminum Silicates/chemistry , Nanotubes/chemistry , Tissue Scaffolds/chemistry , Clay , Elastic Modulus , Nanotubes/ultrastructure , Static ElectricityABSTRACT
Among non-cancer effects of arsenic, cardiovascular diseases have been well documented; however, few are known about the arsenic fate in cardiovascular tissues. We studied the analytic bioinorganic arsenic behaviour in cardiovascular tissues from an arsenic exposure coronary heart disease patient group from Antofagasta-Chile against a small unexposed arsenic coronary heart patient group. Total arsenic concentrations were measured in pieces of cardiovascular tissues of the arsenic-exposed and unexposed coronary heart patient groups by hydride generation atomic absorption spectrometry (HG-AAS); speciation analysis was made by high performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). Pieces of auricle (AU), mammary artery (MAM), saphenous vein (SAP) and fat residuals (FAT) were considered in this study. The arsenic concentrations in AU and MAM tissues were significantly different between both groups of patients. Also, it was demonstrated that the AU is an 'As(3+) target tissue.' Otherwise, linking of the total concentrations of arsenic with conditional variables and variables related to medical geology factors allowed us to infer that the latter are more important for the cardiovascular risk of arsenic exposure in the Antofagasta region. Knowledge of total arsenic and the prevalence of the trivalent ion (As(3+)) in the AU of patients could contribute to understanding the effect of arsenic on cardiovascular diseases.
Subject(s)
Arsenic/toxicity , Cardiovascular Diseases/chemically induced , Cardiovascular System/metabolism , Environmental Exposure/adverse effects , Water Pollutants, Chemical/toxicity , Adult , Aged , Arsenic/isolation & purification , Arsenic/pharmacokinetics , Cardiovascular Diseases/epidemiology , Cardiovascular Diseases/metabolism , Chile/epidemiology , Chromatography, High Pressure Liquid , Environmental Exposure/analysis , Humans , Middle Aged , Spectrophotometry, Atomic , Water Pollutants, Chemical/isolation & purification , Water Pollutants, Chemical/pharmacokineticsABSTRACT
We report on spatial control of nanoporosity in polyelectrolyte multilayer (PEM) films using photopatterning and its effects on film optical and adsorption properties. Multilayers assembled from poly(acrylic acid-ran-vinylbenzyl acrylate) (PAArVBA), a photo-cross-linking polymer, and poly(allylamine hydrochloric acid) (PAH) were patterned using ultraviolet light followed by immersion in low pH and then neutral pH solutions to induce nanoporosity in unexposed regions. Model charged small molecules rhodamine B, fluorescein, and propidium iodide and the model protein albumin exhibit increased adsorption to nanoporous regions of patterned PEM films as shown by fluorescence microscopy and radiolabeling experiments. Films assembled with alternating stacks of PAH/poly(sodium-4-styrene sulfonate) (SPS), which do not become nanoporous, and stacks of PAH/PAArVBA were patterned to create nanoporous capillary channels. Interdigitated channels demonstrated simultaneous, separate wicking of dimethyl sulfoxide-solvated fluorescein and rhodamine B. In addition, these heterostack structures exhibited patternable Bragg reflectivity of greater than 25% due to refractive index differences between the nanoporous and nonporous stacks. Finally, the PEM assembly process coupled with photo-cross-linking was used to create films with two separate stacked reflective patterns with a doubling in reflectivity where patterns overlapped. The combined adsorptive and reflective properties of these films hold promise for applications in diagnostic arrays and therapeutics delivery.
ABSTRACT
We report the synthesis of poly(acrylic acid-ran-vinylbenzyl acrylate) (PAArVBA), a photo-cross-linkable weak polyelectrolyte, and its incorporation into polyelectrolyte multilayer (PEM) films. PEM films assembled from PAArVBA and poly(allylamine hydrochloride) (PAH) are found to exhibit similar thickness trends with assembly pH as those previously reported for poly(acrylic acid) (PAA)/PAH multilayers. Swelling properties of the as-built and photo-cross-linked films are studied by in situ ellipsometry. Two-dimensional masking techniques are used to pattern regions of high and low swelling, as confirmed by atomic force microscopy (AFM), and to provide spatial control over the low-pH-induced microporosity transition exhibited by PAH/PAA PEMs. Films containing alternating blocks of PAH/PAArVBA bilayers and PAH/PAA bilayers were assembled, laterally photopatterned, and exposed to low-pH solution to generate nanoporosity leading to patterned Bragg reflectors, thereby demonstrating three-dimensional control over film structure in these weak PEM assemblies.
ABSTRACT
A study has been made of the effect of urea upon the hydrolysis of 2-naphthyl acetate (2-NA) catalyzed by lipase from Rhizopus arrhizus in AOT-heptane-water reverse micellar solutions at pH 7. The partition constants, K, of 2-NA between n-heptane and aqueous urea solutions in the absence of micelles were also determined. It was found that K decreases when the concentration of urea increases. In aqueous solution the rate of hydrolysis of 2-NA catalyzed by lipase is dependent on the concentration of urea (at a given 2-NA concentration). This result can be due to a decrease in the magnitude of the association of lipase with 2-NA and/or to changes in the reaction rate of the lipase-2-NA complex. The modifications of the enzymatic activities elicited by addition of urea show a lineal correlation with K, emphasizing the relevance of hydrophobic effects in the loss of activity. Nevertheless, the slope of the line is higher than one, suggesting that changes in the conformation of the enzyme would be also important. Addition of urea to the micellar solutions provokes a decrease of the enzyme activity. From the dependence of the reaction rate with AOT concentration, the partition constant of 2-NA between n-heptane and the micelles, K(p), was obtained. In the presence of 2 M urea a value of K(p)=0.33 M(-1) was derived. This value is lower than that measured in the absence of urea (Aguilar et al., Arch. Biochem. Biophys. 388 (2001) 231), indicating that incorporation of urea to the micellar interface produces a decrease of the association of 2-NA with the micelles. From a comparison of the results obtained in the micellar solution and in aqueous solution, it is concluded that the enzyme is more resistant to denaturation by urea in the micellar solution than in aqueous solution. Furthermore, at intermediate urea concentrations (2 M), the additive produces an increase in the Michaelis constant (K(M)) without a significant decrease (or even a small increase) in the catalytic rate constant (k(cat)).
Subject(s)
Lipase/chemistry , Micelles , Urea/chemistry , Catalysis , Dose-Response Relationship, Drug , Heptanes/chemistry , Hydrogen-Ion Concentration , Hydrolysis , Kinetics , Microscopy, Fluorescence , Naphthaleneacetic Acids/chemistry , Time Factors , Water/chemistryABSTRACT
Echinococcus disease is prevalent in Chile, with a rate of occurrence of 8.2 per 100,000. During a 15-year-period (1970 to 1985) we operated on 331 patients for pulmonary hydatidosis. Chest roentgenography was the main method of diagnosis. Among the total of 508 surgical procedures performed, pulmonary cystectomy was the most common (61.4%), whereas pulmonary resection was used in 31.4% of patients. The arc 5 test was used to confirm the diagnosis. Results were positive in 85% of the patients in whom it was done. There were 12.9% immediate postoperative complications in 12.9%, with late complications occurring in 4.10% and an overall mortality rate of 4.21%. These data suggest that hydatid cyst is still a common disease in our country, causing an important number of hospital admissions and a high percentage of complications.
Subject(s)
Echinococcosis, Pulmonary/surgery , Echinococcosis, Pulmonary/diagnostic imaging , Echinococcosis, Pulmonary/mortality , Female , Humans , Male , Postoperative Complications , Radiography , Surgical Procedures, Operative/methodsABSTRACT
Estudio clínico endoscópico, doble ciego, realizado en 10 centros gastroenterológicos argentinos, en 116 pacientes, con diagnósticos de úlcera duodenal activa, que recibieron, en forma randomizada. Misoprostol 800 microng o Cimetidina 1.200 mg, distribuidos en cuatro dosis diarias, durante cuatro semanas, con controles clínicos y bioquímicos semanales, registando los efectos adversos, y permitiendo sólo la toma de Amphogel de acuerdo a necesidades. Los resultados obtenidos sobre 99 pacientes evaluables 54 con Misoprostol y 45 con Cimetidina, fueron estudiados. El critério de curación se basó en al cicatrización completa por documentción en la cicatrización complera por documentación endoscópica al finalizar el tratamiento. El índice de curación obtenido fue de 85,2% (465/54) para el Misoprostol y de 75,5% (34/45) para la Cimetidina, diferencia no significativa estadísticametne. Se concluye que el Misoprostol y la Cimetidina son igualmente efectivos y seguros en el tratamiento de la ulcera duodenal activa y sin efectos adversos importantes. El Misosprostol es una nueva alternativa terapéutica para el tratamiento de la úlcera duodenal
Subject(s)
Adolescent , Adult , Middle Aged , Humans , Male , Female , Alprostadil/therapeutic use , Duodenal Ulcer/drug therapy , Anti-Ulcer Agents/therapeutic use , Cimetidine/therapeutic use , Clinical Trials as Topic , Double-Blind Method , Duodenoscopy , Multicenter Studies as Topic , Random AllocationABSTRACT
Estudio clínico endoscópico, doble ciego, realizado en 10 centros gastroenterológicos argentinos, en 116 pacientes, con diagnósticos de úlcera duodenal activa, que recibieron, en forma randomizada. Misoprostol 800 microng o Cimetidina 1.200 mg, distribuidos en cuatro dosis diarias, durante cuatro semanas, con controles clínicos y bioquímicos semanales, registando los efectos adversos, y permitiendo sólo la toma de Amphogel de acuerdo a necesidades. Los resultados obtenidos sobre 99 pacientes evaluables 54 con Misoprostol y 45 con Cimetidina, fueron estudiados. El critério de curación se basó en al cicatrización completa por documentción en la cicatrización complera por documentación endoscópica al finalizar el tratamiento. El índice de curación obtenido fue de 85,2% (465/54) para el Misoprostol y de 75,5% (34/45) para la Cimetidina, diferencia no significativa estadísticametne. Se concluye que el Misoprostol y la Cimetidina son igualmente efectivos y seguros en el tratamiento de la ulcera duodenal activa y sin efectos adversos importantes. El Misosprostol es una nueva alternativa terapéutica para el tratamiento de la úlcera duodenal (AU)
Subject(s)
Adolescent , Adult , Middle Aged , Aged , Humans , Male , Female , Comparative Study , Duodenal Ulcer/drug therapy , Alprostadil/therapeutic use , Anti-Ulcer Agents/therapeutic use , Cimetidine/therapeutic use , Clinical Trials as Topic , Double-Blind Method , Random Allocation , Duodenoscopy , Multicenter Studies as TopicABSTRACT
Ten Argentine centers participated in this cooperative trial. One hundred and sixteen patients with endoscopically proven duodenal ulcer entered the study and were randomly assigned to receive either Misoprostol 800 micrograms or Cimetidine 1200 mg, q.i.d. per day, during four weeks of treatment. Patients were allowed to take Amphogel tablets for relief of ulcer pain when necessary, and clinical, lab-tests and adverse effects were evaluated weekly. Ninety-nine patients (Misoprostol 54, Cimetidine 45) completed the study and were evaluable. Success/failure criteria were based on endoscopically documented complete healing at the end of treatment period. Healing rate of four week was 85.2 per cent (46/54) for Misoprostol and 75.5 per cent (34/45) for Cimetidine, with no statistically significant difference. It is concluded that Misoprostol and Cimetidine are highly effective and safety in the healing of active duodenal ulcer. Misoprostol is a new therapeutical alternative for the treatment of duodenal ulcer patients.
Subject(s)
Alprostadil/analogs & derivatives , Cimetidine/therapeutic use , Duodenal Ulcer/drug therapy , Adolescent , Adult , Aged , Alprostadil/adverse effects , Alprostadil/therapeutic use , Cimetidine/adverse effects , Clinical Trials as Topic , Double-Blind Method , Duodenal Ulcer/pathology , Duodenoscopy , Humans , Middle Aged , Misoprostol , Multicenter Studies as Topic , Random AllocationABSTRACT
Ten Argentine centers participated in this cooperative trial. One hundred and sixteen patients with endoscopically proven duodenal ulcer entered the study and were randomly assigned to receive either Misoprostol 800 micrograms or Cimetidine 1200 mg, q.i.d. per day, during four weeks of treatment. Patients were allowed to take Amphogel tablets for relief of ulcer pain when necessary, and clinical, lab-tests and adverse effects were evaluated weekly. Ninety-nine patients (Misoprostol 54, Cimetidine 45) completed the study and were evaluable. Success/failure criteria were based on endoscopically documented complete healing at the end of treatment period. Healing rate of four week was 85.2 per cent (46/54) for Misoprostol and 75.5 per cent (34/45) for Cimetidine, with no statistically significant difference. It is concluded that Misoprostol and Cimetidine are highly effective and safety in the healing of active duodenal ulcer. Misoprostol is a new therapeutical alternative for the treatment of duodenal ulcer patients.
ABSTRACT
Los autores presentan su experiencia clinica em el tratamiento de la pancreatitis aguda de origen biliar, realizando esfinteropapilotomia endoscopica en urgencia para extraer calculos que obstruian el orificio ampular de la papila y/o el coledoco terminal, causa etiologica de la inflamacion aguda del pancreas. La serie comprende 4 pacientes portadores de pancreatitis aguda biliar tratados por este metodo, cuyos resultados inmediatos y alejados fueron satisfactorios
Subject(s)
Adult , Middle Aged , Humans , Male , Female , Ampulla of Vater , Cholangiopancreatography, Endoscopic Retrograde , Cholestasis , Pancreatitis , Surgical Procedures, OperativeSubject(s)
Adult , Middle Aged , Humans , Male , Female , Ampulla of Vater , Common Bile Duct NeoplasmsABSTRACT
Los autores presentan su experiencia clinica em el tratamiento de la pancreatitis aguda de origen biliar, realizando esfinteropapilotomia endoscopica en urgencia para extraer calculos que obstruian el orificio ampular de la papila y/o el coledoco terminal, causa etiologica de la inflamacion aguda del pancreas. La serie comprende 4 pacientes portadores de pancreatitis aguda biliar tratados por este metodo, cuyos resultados inmediatos y alejados fueron satisfactorios
Subject(s)
Adult , Middle Aged , Humans , Male , Female , Ampulla of Vater , Cholangiopancreatography, Endoscopic Retrograde , Cholestasis , Pancreatitis , Surgical Procedures, OperativeSubject(s)
Adult , Middle Aged , Aged , Humans , Male , Female , Ampulla of Vater , Common Bile Duct NeoplasmsABSTRACT
We have made an analysis of correlation between Secretin Test and Retrograde pancreatography in 25 patients. Using Secretin Test, in these comparative evaluation we confirmed the predictive values of normality or pathological alteration of the gland obtained through functional exploration of the pancreon. In consequence it's correct to use this test as a first mean of establishing the presence of pancreatic pathologies.
Subject(s)
Cholangiopancreatography, Endoscopic Retrograde , Pancreatic Diseases/diagnosis , Pancreatic Function Tests , Secretin , Adult , Diagnosis, Differential , Female , Humans , Male , Middle Aged , Pancreatic Juice/metabolismABSTRACT
Se ha efectuado, en 25 pacientes, un analisis de correlacion entre el test de Secretina y la pancreatografia retrograda. El valor predictivo de normalidad o de alteracion patologica de la glandula brindado por la exploracion funcional del pancreon mediante el test de secretina es confirmado en esta evaluacion comparativa. Esto justifica que este examen sea utilizado como un primer medio de "rastreo" en el estudio de las diferentes pancreatopatias
