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1.
Mitochondrial DNA A DNA Mapp Seq Anal ; 30(3): 500-510, 2019 04.
Artículo en Inglés | MEDLINE | ID: mdl-30691341

RESUMEN

The partial sequences of cytochrome c oxidase subunit I (COI) mitochondrial gene were analysed for developing species specific molecular signatures and phylogenetic relationship among the commercially important flying fishes (Cheilopogon cyanopterus, Cheilopogon furcatus and Hirundichthys coromandelensis) distributed in Tamil Nadu coast. Accurate identification of these species is important for fishery management as its morphological characters are very similar. Since the morphological features are very similar, accurate identification using molecular tools is essential for sustainable utilization and management of these species across their distributional range. The estimated transition/transversion bias (R) is 3.45. The average nucleotide sequences calculated were A = 30.00%, T/U = 26.40%, C = 17.00% and G = 26.60%. Using COI data analysis, the intraspecies genetic distance ranged from 0.00 to 0.05, while it varied from 0.06 to 0.08 for interspecies. Partial sequences of the genes provided sufficient phylogenetic information to distinguish the three flying fishes indicating the usefulness of mtDNA-based approach in species identification.


Asunto(s)
ADN Mitocondrial/genética , Explotaciones Pesqueras/organización & administración , Peces/clasificación , Peces/genética , Tipificación Molecular , Filogenia , Animales , India
2.
Rozhl Chir ; 91(1): 26-31, 2012 Jan.
Artículo en Checo | MEDLINE | ID: mdl-22746075

RESUMEN

INTRODUCTION: Severe peritonitis is a frequent condition characterized by high morbidity and mortality rates. Topical negative pressure (TNP) laparostomy could improve the results of the treatment, provided that the adverse events of this method are reduced. The aim of our study was to prove, in a prospective randomized study, that the primary use of TNP laparostomy reduces morbidity and mortality when compared to primary abdominal wall closure after the index surgery for severe peritonitis. The possibility of the abdominal wall fascial closure significantly influencing morbidity was the main topic of this study. MATERIAL AND METHODS: Between 9/2009 and 9/2011,57 patients with severe peritonitis were included in the study at the Department of Surgery of the Bulovka Faculty Hospital; 28 of them were randomized to the TNP laparostomy group and 29 to the primary closure group. The two groups did not differ in age, gender, polymorbidity and severity of peritonitis. RESULTS: The length of hospital stay was similar in both groups (median: 22 days; range 10-171 days) in the intervention group and 23 days (range 3-71) in the control group (p = 0.89). The mortality rate was significantly lower in the TNP laparostomy group in comparison with the primary closure group (3 patients, 11% vs. 12 patients, 41%; p = 0.01). A complete closure of the abdominal wall including fascia and complete abdominal wall healing was achieved in 80% of survivors in the TNP group, compared to 29% in the primary closure group (p = 0.01). No enteral fistula occurred in any surviving patients from both groups. The overall length of abdominal wall healing was significantly shorter in the TNP group (median: 7; 7-94 days, versus 30; 7-223; p = 0.04). CONCLUSIONS: Primary TNP laparostomy is an effective and safe method in the treatment of severe peritonitis. Keeping good clinical practice, especially using dynamic suture as early as after the index surgery and the timely closure of laparostomy as soon as the indication disappears (according to relevant criteria) leads to a significantly higher abdominal wall healing rate, icluding fascial closure, than after peritonitis treatment without laparostomy.


Asunto(s)
Pared Abdominal/cirugía , Fasciotomía , Laparotomía , Terapia de Presión Negativa para Heridas , Peritonitis/cirugía , Técnicas de Sutura , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad
3.
Eur J Obstet Gynecol Reprod Biol ; 158(2): 285-8, 2011 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-21664027

RESUMEN

OBJECTIVE: Endometriosis is one of the most frequent gynaecological disorders being associated with infertility. Hence, the early detection of endometriosis in infertility patients is of importance for the treatment modalities in infertility. Transvaginal hydrolaparoscopy (THL) offers an accurate, safe and quick diagnostic tool, not only for the evaluation of the fallopian tubes but also for the detection of very subtle endometriotic lesions in the early stages of endometriosis. STUDY DESIGN: Between January 2008 and January 2010, we conducted a study in order to evaluate the prevalence, extent and localisation of endometriosis via the new technique of THL in infertility patients. 239 patients with a mean age of 33.9 years underwent THL after having given informed consent. RESULTS: In 237 patients, access to the cul-de-sac was successfully achieved. Endometriosis was detected in 77 of 237 cases (32.5%). In 85.7% of cases, the endometriotic lesions were classified as very small (ASRM stage I°). Predominantly, the small lesions were found merely on the left side of the patient's peritoneal cavity: in 43 cases (55.8%), endometriosis was detected strictly on the left side, whereas the disease was detected on the right side in only 5 patients (6.5%). In 29 patients, endometriosis could be detected in both sides of the pelvis (37.7%). The differences in the side-dependent distribution were statistically highly significant (p<0.0001). In most of the cases, the subtle endometriotic lesions affected the ovarian surface superficially (53.5%) or the peritoneum of the lateral pelvic wall (25.6%). CONCLUSIONS: These data clearly indicate that there is a high prevalence of endometriosis in patients with infertility. THL is an accurate, safe and quick method for a thorough examination of the female pelvis besides the patency of the fallopian tubes. The high prevalence of left-sided subtle endometriotic lesions must be interpreted that during THL a very early process in the development of endometriosis can be observed. Even minimal to mild endometriosis might lead to a significant restriction in uterotubal transport capacity whose integrity is directly correlated to normal pregnancy rates. The extent of the accompanying adenomyosis is directly correlated to the loss of intact uterotubal transport capacity.


Asunto(s)
Endometriosis/diagnóstico , Adulto , Susceptibilidad a Enfermedades , Endometriosis/complicaciones , Femenino , Humanos , Infertilidad Femenina/etiología , Laparoscopía
4.
Nuklearmedizin ; 47(1): 13-7, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-18278207

RESUMEN

AIM: This study was performed to determine the results of ablative radioiodine therapy (RIT) when the achieved dose in the thyroid was above 200 Gy and to characterize predictive factors for treatment outcome. PATIENTS, METHODS: A total of 571 consecutive patients were observed for 12 months between July 2001 and June 2004. Inclusion criteria were a confirmed diagnosis Graves' disease, compensation of hyperthyroidism and withdrawal of antithyroid drugs two days before preliminary radioiodine-testing and RIT. The intended dose was 250 Gy and the therapeutically achieved dose was calculated from serial uptake measurements. The end-point measure was thyroid function 12 months after RIT; success was defined as elimination of hyperthyroidism. The relation between success rate and the achieved dose, thyroid volume, age and sex of patients, TSH- and TRAb-values and presence of ophthalmopathy was analysed. RESULTS: Relief from hyperthyroidism was achieved in 96% of patients who received more than 200 Gy, even for thyroid volumes >40 ml. The success of ablative RIT was not influenced by age or sex of patients, or by TSH- or TRAb values or concomitant ophthalmopathy. The mean achieved dose in the thyroid was 298 Gy with a standard deviation of 74.6 Gy. CONCLUSION: To achieve a dose of over 200 Gy with the above standard deviation, we recommend calculating an intended dose of 250 Gy and using a dosimetric approach with early and late uptake values in the radioiodine test, to allow early therapeutic intervention should the posttherapeutic thyroid dose fall unexpectedly below 200 Gy.


Asunto(s)
Enfermedad de Graves/radioterapia , Radioisótopos de Yodo/uso terapéutico , Radioterapia/métodos , Adulto , Humanos , Persona de Mediana Edad , Tamaño de los Órganos , Radioisótopos/uso terapéutico , Dosificación Radioterapéutica , Estudios Retrospectivos , Glándula Tiroides/anatomía & histología , Glándula Tiroides/efectos de la radiación , Tirotropina/sangre
5.
Radiat Prot Dosimetry ; 126(1-4): 615-8, 2007.
Artículo en Inglés | MEDLINE | ID: mdl-17522032

RESUMEN

High-energy (12)C ions offer favourable conditions for the treatment of deep-seated local tumours. Several facilities for the heavy ion therapy are planned or under construction, for example the new clinical ion-therapy unit HIT at the Radiological University Clinics in Heidelberg. In order to improve existing treatment planning models, it is essential to evaluate the secondary fragment production and to include these contributions to the therapy dose with higher accuracy. Secondary neutrons are most abundantly produced in the reactions between (12)C beams and tissues. The dose contribution to tissues by a neutron is fairly small compared with the projectile and the other charged fragments due to no ionisation and the small reaction cross-sections; however, it distributes in a considerably wider region beyond the bragg-peak because of the strong penetrability. Systematic data on energy spectra and doses of secondary neutrons produced by (12)C beams using water targets of different thicknesses for various detection angles have therefore been measured in this study at GSI Darmstadt.


Asunto(s)
Radioisótopos de Carbono/uso terapéutico , Radioterapia de Iones Pesados , Modelos Biológicos , Neutrones , Radiometría/métodos , Planificación de la Radioterapia Asistida por Computador/métodos , Agua/química , Simulación por Computador , Humanos , Dosificación Radioterapéutica
6.
Biosens Bioelectron ; 16(9-12): 773-82, 2001 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-11679255

RESUMEN

The quartz crystal microbalance (QCM) was used to create a piezoelectric biosensor utilizing living endothelial cells (ECs) as the biological signal transduction element. ECs adhere to the hydrophilically treated gold QCM surface under growth media containing serum. At 24 h following cell addition, calibration curves were constructed relating the steady state Deltaf and DeltaR shift values observed to the numbers of electronically counted cells requiring trypsinization to be removed from the surface. We then utilized this EC QCM biosensor for the detection of the effect of [nocodazole] on the steady state Deltaf and DeltaR shift values. Nocodazole, a known microtubule binding drug, alters the cytoskeletal properties of living cells. At the doses used in these studies (0.11-15 microM), nocodazole, in a dose dependent fashion, causes the depolymerization of microtubules in living cells. This leads a monolayer of well spread ECs to gradually occupy a smaller area, lose cell to cell contact, exhibit actin stress fibers at the cell periphery and acquire a rounded cell shape. We observed the negative Deltaf shift values and the positive DeltaR shift values to increase significantly in magnitude over a 4-h incubation period following nocodazole addition, in a dose dependent fashion, with a transition midpoint of 900 nM. Fluorescence microscopy of the ECs, fixed on the gold QCM surface and stained for actin, demonstrated that the shape and cytoskeleton of ECs were affected by as little as 330 nM nocodazole. These results indicate that the EC QCM biosensor can be used for the study of EC attachment and to detect EC cytoskeletal alterations. We suggest the potential of this cellular biosensor for the real time identification or screening of all classes of biologically active drugs or biological macromolecules that affect cellular attachment, regardless of their molecular mechanism of action.


Asunto(s)
Técnicas Biosensibles/instrumentación , Microtúbulos/efectos de los fármacos , Nocodazol/farmacología , Actinas/metabolismo , Animales , Bovinos , Células Cultivadas , Citoesqueleto/efectos de los fármacos , Endotelio Vascular/citología , Endotelio Vascular/efectos de los fármacos , Endotelio Vascular/metabolismo , Microscopía Fluorescente , Cuarzo , Transducción de Señal
7.
Exp Parasitol ; 98(4): 215-22, 2001 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-11560414

RESUMEN

A cDNA encoding a Ca-ATPase homologue, designated SMA3, was isolated from an adult cDNA library of Schistosoma mansoni. The full-length cloned DNA contains a 3105-bp open reading frame that potentially encodes a 1035-amino-acid protein with a M(r) of 113,729 and a pl of 6.48. Homology searches for SMA3 reveal high sequence identity with a variety of Ca-ATPases from evolutionarily diverse organisms. SMA3 is predicted to contain 10 transmembrane regions typical of this protein family as well as other conserved domains, such as the phosphorylation site and FITC binding domain. The greatest sequence identity (40-50%) is found to those Ca-ATPases belonging to the secretory pathway subclass. Identification of the 5' end of the SMA3 cDNA by RACE analysis reveals the presence of a 36-base spliced leader RNA, suggesting that the SMA3 pre-mRNA is processed by trans-splicing. Northern analysis reveals a single dominant transcript of 5 kb in adult RNA preparations. Antibodies raised against an amino terminal peptide detect the protein in the adult tegument, suggesting that SMA3 functions to help control Ca homeostasis within the tegument and may play a role in signal transduction at the host parasite interface.


Asunto(s)
Proteínas de Caenorhabditis elegans , ATPasas Transportadoras de Calcio/genética , Schistosoma mansoni/enzimología , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Northern Blotting , ATPasas Transportadoras de Calcio/análisis , ATPasas Transportadoras de Calcio/química , ADN Complementario/química , ADN de Helmintos/química , Femenino , Proteínas del Helminto/análisis , Proteínas del Helminto/química , Proteínas del Helminto/genética , Masculino , Microscopía Fluorescente , Datos de Secuencia Molecular , Filogenia , ARN de Helminto/análisis , ARN de Helminto/genética , Schistosoma mansoni/clasificación , Schistosoma mansoni/genética
8.
Cytometry ; 44(1): 45-56, 2001 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-11309808

RESUMEN

BACKGROUND: Programmed cell death, also termed apoptosis, is the main focus of interest in a variety of scientific and clinical areas. For a better understanding of the mechanisms of apoptosis, from the onset of the cellular death program to the late stages of apoptosis or apoptotic necrosis, very early functional events have to be quantified because they might be involved in temporal and causal relationships between apoptosis-related key processes. METHODS: We have established a flow cytometric technique to quantify time-dependent signals simultaneously with high temporal resolution (Deltat = 1 s) in living cells. With this technique, the response of cells to apoptosis-stimulating agents can be analyzed over 15 min. For this purpose, a thermostatted sample tube holder for repeatable interruption-free injection of substances into the cell suspension was developed. Early detectable fluorescence and scatter parameters were related to intracellular free Ca2+ concentration, [Ca2+]i (Indo-1 fluorometry), membrane permeability (propidium iodide [PI] influx), and cell volume (forward scatter). RESULTS: A T-cell line (Jurkat) served as a model system. Apoptosis was induced by the biozid Tri-n-butyltin (TBT). Dependent on the TBT concentration (0.3-10 microM), the mean free [Ca2+]i increased by a factor of 1.2-6 during a short time interval of just 2 min. Especially after low TBT concentrations (< 0.5 microM), this [Ca2+]i increase was nearly transient during the observation time of 15 min. Higher TBT concentrations (0.5-10 microM), however, induced a transient increase of [Ca2+]i (Ca-TR) only in a fraction of the cells; in another subpopulation, a steady-state Ca2+ signal (Ca-SST) was observed. The analysis of the simultaneously registered PI signals of the Ca-SST cells showed a shift to increasing PI fluorescence (by a factor of about 4) with increasing Ca2+ concentrations. In Ca-TR cells, the PI fluorescence remained nearly unchanged. These apoptosis-related changes (increase in [Ca(2+)]i and membrane permeability) could be confirmed by the additional observation of a TBT concentration-dependent decrease in cell volume measured during the same early time period. CONCLUSIONS: The simultaneously analyzed parameters (i.e., [Ca2+]i, membrane permeability, and cell volume) suggested that, in our model system of Jurkat T-cells treated with TBT, an apoptotic cell fate was indicated very early (within 15 min) by the steady-state [Ca2+]i level.


Asunto(s)
Apoptosis , Timo/citología , Compuestos de Trialquiltina/farmacología , Calcio/metabolismo , Relación Dosis-Respuesta a Droga , Procesamiento Automatizado de Datos , Humanos , Indicadores y Reactivos , Células Jurkat , Necrosis , Propidio , Factores de Tiempo
10.
Chemistry ; 6(11): 2063-8, 2000 Jun 02.
Artículo en Inglés | MEDLINE | ID: mdl-10894406

RESUMEN

Base treatment of the pyridinium bromides 11a-e gives rise to the formation of the dihydropyridoazepines 14a-e as the only monomolecular products. The reaction takes place by initial deprotonation to the ylides 12, which undergo 8pi-electrocyclization affording the seven-membered-ring systems; no products of a dipolar 6pi-cyclization were detected. On the basis of quantum mechanical calculations a rationalization of the periselectivity of the electrocyclization process is given.

13.
Biotechnol Prog ; 16(2): 268-77, 2000.
Artículo en Inglés | MEDLINE | ID: mdl-10753454

RESUMEN

The quartz crystal microbalance (QCM) was used to monitor endothelial cell (EC) adhesion on the gold surface of an oscillating quartz crystal contained in a QCM device. A number of parameters were investigated. First, we observed differential QCM O-ring toxicities for ECs. Second, appropriate conditions for cell culture and QCM cell environment were identified that can eliminate large-scale frequency oscillations in the measurements. These artifacts are not due to added cells but originate in the time-dependent evaporation of water. Having eliminated these artifacts, we then demonstrated that the measured steady-state crystal frequency shift, Delta f, and motional resistance shift, DeltaR, were determined by the number of firmly attached ECs requiring trypsinization from the crystal surface. Last, following steady-state attachment of ECs, the EC growth stimulation by fibroblast growth factor was monitored in a continuous fashion by measuring f and R values over a 72 h. period. We observed the Delta f values to increase in a way that reflected the increase in EC number bound to the QCM surface. Following addition of ECs to the QCM, the time-dependent increase in DeltaR can be interpreted in terms of increase by the ECs of the energy dissipation properties of the solution at the solution-gold surface interface. This effect is due to their rapid surface attachment and the elaboration of their cytoskeletal properties. These results indicate that the QCM technique can be used for the study of EC attachment and growth and suggest its potential for the real time study of per unit surface area cell mass distribution dynamics and viscoelastic properties and the cells' responses to stresses or perturbations brought about using biologically active molecules.


Asunto(s)
Técnicas Citológicas , Endotelio Vascular/citología , Animales , Bovinos , Adhesión Celular/efectos de los fármacos , División Celular/efectos de los fármacos , Técnicas Citológicas/instrumentación , Endotelio Vascular/efectos de los fármacos , Factores de Crecimiento de Fibroblastos/farmacología , Tripsina/farmacología
15.
J Parasitol ; 86(1): 146-9, 2000 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-10701578

RESUMEN

The genetic differences between Schistosoma mansoni strains from different geographic areas that were reportedly resistant or sensitive to anti-schistosomal drugs were studied with randomly amplified polymorphic DNA (RAPD) and simple sequence repeat (SSR) polymerase chain reaction (PCR) assays. Of the 20 RAPD primers we chose, 19 showed the capacity to produce a medium to high level of amplification and 6 revealed difference PCR bands between drug-resistant and drug-sensitive strains. One particular primer, 5'-CAGCGACAAG-3', showed 2 major difference bands between praziquantel (PZQ)-resistant and PZQ-sensitive strains from the endemic area of Egypt. These results demonstrate that defined sequence primers could be applied as a useful tool for differentiating drug-resistant and -sensitive schistosome parasites in the field.


Asunto(s)
Técnica del ADN Polimorfo Amplificado Aleatorio , Schistosoma mansoni/efectos de los fármacos , Esquistosomicidas/farmacología , Animales , Dermatoglifia del ADN , Cartilla de ADN/química , ADN de Helmintos/análisis , ADN de Helmintos/química , Resistencia a Medicamentos/genética , Ratones , Schistosoma mansoni/genética
17.
Biophys J ; 77(1): 114-22, 1999 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-10388744

RESUMEN

In this paper we introduce an important parameter called the iso-competition point (ICP), to characterize the competition binding to DNA in a two-cation-species system. By imposing the condition of charge neutralization fraction equivalence theta1 = ZthetaZ upon the two simultaneous equations in Manning's counterion condensation theory, the ICPs can be calculated. Each ICP, which refers to a particular multivalent concentration where the charge fraction on DNA neutralized from monovalent cations equals that from the multivalent cations, corresponds to a specific ionic strength condition. At fixed ionic strength, the total DNA charge neutralization fractions thetaICP are equal, no matter whether the higher valence cation is divalent, trivalent, or tetravalent. The ionic strength effect on ICP can be expressed by a semiquantitative equation as ICPZa/ICPZb = (Ia/Ib)Z, where Ia, Ib refers to the instance of ionic strengths and Z indicates the valence. The ICP can be used to interpret and characterize the ionic strength, valence, and DNA length effects on the counterion competition binding in a two-species system. Data from our previous investigations involving binding of Mg2+, Ca2+, and Co(NH3)63+ to lambda-DNA-HindIII fragments ranging from 2.0 to 23.1 kbp was used to investigate the applicability of ICP to describe counterion binding. It will be shown that the ICP parameter presents a prospective picture of the counterion competition binding to polyelectrolyte DNA under a specific ion environment condition.


Asunto(s)
Unión Competitiva , Cationes/química , ADN/química , Oligodesoxirribonucleótidos/química , Concentración Osmolar
18.
Biotechnol Prog ; 15(3): 522-8, 1999.
Artículo en Inglés | MEDLINE | ID: mdl-10356273

RESUMEN

Amphiphilic decyl derivatives of D-tyrosine self-assemble into long rodlike or tubular aggregate structures in aqueous buffered solution. In this report we demonstrate the novel use of the quartz crystal microbalance (QCM) to measure the presence in solution, and subequent enzymatic polymerization, of long rodlike monomer aggregates of the decyl ester of D-tyrosine (DEDT) as a function of their formation and increasing surface binding level as pH values increase from 3 to 7. From these data, using the Sauerbray equation to calculate the effective elastic mass surface binding of deprotonated DEDT aggregates, a pKapp of 8.3 is obtained for the DEDT alpha-NH2 group protonation-deprotonation and subsequent aggregation equilibrium. Furthermore, once aggregates are bound to the QCM surface, we initiate and subsequently monitor enzymatic polymerization of the DEDT monomers by horseradish peroxidase through the measurement of significant changes in the quartz crystal frequency and motional resistance. Following the onset of polymerization, the viscoelastic properties of the bound monomer aggregates change. A final polymerized state is achieved in which the altered physical properties of the polymerized rodlike aggregates make the solution immediately above the QCM surface-solution interface behave as a Newtonian fluid, producing a nearly pure viscosity-density energy dissipative effect on the measured crystal frequency and motional resistance values.


Asunto(s)
Tirosina/análogos & derivados , Biotecnología , Elasticidad , Concentración de Iones de Hidrógeno , Sustancias Macromoleculares , Micelas , Polímeros/química , Polímeros/aislamiento & purificación , Cuarzo , Tirosina/química , Tirosina/aislamiento & purificación , Viscosidad , Agua
19.
Bioinformatics ; 15(5): 370-5, 1999 May.
Artículo en Inglés | MEDLINE | ID: mdl-10366657

RESUMEN

MOTIVATION: MELTSIM is a windows-based statistical mechanical program for simulating melting curves of DNAs of known sequence and genomic dimensions under different conditions of ionic strength with great accuracy. The program is useful for mapping variations of base compositions of sequences, conducting studies of denaturation, establishing appropriate conditions for hybridization and renaturation, determinations of sequence complexity, and sequence divergence. RESULTS: Good agreement is achieved between experimental and calculated melting curves of plasmid, bacterial, yeast and human DNAs. Denaturation maps that accompany the calculated curves indicate non-coding regions have a significantly lower (G+C) composition than coding regions in all species examined. Curves of partially sequenced human DNA suggest the current database may be heavily biased with coding regions, and excluding large (A+T)-rich elements. AVAILABILITY: MELTSIM 1.0 is available at: //www.uml.edu/Dept/Chem/UMLBIC/Apps/MEL TSIM/MELTSIM-1.0-Win/meltsim. zip. Melting curve plots in this paper were made with GNUPLOT 3.5, available at: http://www.cs.dartmouth.edu/gnuplot_inf o.html Contact : blake@maine.maine.edu;


Asunto(s)
Simulación por Computador , ADN/análisis , Modelos Estadísticos , Programas Informáticos , Composición de Base , ADN Bacteriano/análisis , ADN de Hongos/análisis , Humanos , Desnaturalización de Ácido Nucleico
20.
Biomaterials ; 19(18): 1657-67, 1998 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-9840001

RESUMEN

We have studied the time-dependent uptake of 35S radiolabeled DNA with electrochemically prepared polypyrrole films. The two distinct polypyrrole film surfaces, a rough (solution polymeric growth face, R) and a smooth surface (electrode face, S) were characterized by low-resolution AFM and high-resolution transmission electron microscopy (TEM). These studies showed the presence of steep contours and defects in the form of large and small surface holes and valleys on the rough surface of polypyrrole. The void dimensions ranged from the nanoscale to micron size. By contrast, the smooth surface was flatter and largely devoid of significant structural defects and exhibited closer packing of the polypyrrole chains over large areas. Both surfaces were comprised largely of chains whose average diameters were 1.0-1.2 +/- 0.3 nm. The surface characterization studies were complemented by time-dependent DNA uptake studies which showed a t1/2-dependent total uptake of 35S DNA at higher levels on the rough surface compared to the smooth surface. This is consistent with the apparent higher effective surface area of the rough surface compared to the smooth. Using a proportional counter the time-dependent ratio (R/S) of the 35S DNA detected from the rough surface of the polypyrrole disk to that detected from the smooth surface suggested that DNA was migrating into the disk interior from its uptake surface. The rough side defect dimensions measured by TEM were more than sufficient to allow for the penetration and migration of DNA into the disk interior. Both R/S ratios were extrapolated and found to intersect at an R/S value close to 1.0, suggesting a kinetic process leading ultimately towards a nearly uniform radiolabeled DNA distribution in the disk. These kinetic results were in agreement with the surface characterization studies and suggest a model in which sizeable internal pores exist throughout the electrochemically prepared polypyrrole, that could account for the DNA migration effect. This was confirmed by TEM of the interior of a polypyrrole disk produced by Argon ion milling.


Asunto(s)
Materiales Biocompatibles/química , ADN/química , Pirroles/química , Adsorción , ADN/metabolismo , Electroquímica , Liofilización , Procesamiento de Imagen Asistido por Computador , Cinética , Microscopía de Fuerza Atómica , Microscopía Electrónica , Polímeros/química , Propiedades de Superficie
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