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1.
Int J Artif Organs ; 47(1): 67-72, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-38142295

RESUMEN

INTRODUCTION: The study aims to present a case of acute mercuric chloride poisoning treated successfully with continuous renal replacement therapy using the CytoSorb filter. CASE DESCRIPTION: A 21-year-old female patient after a suicide attempt by intentional ingestion of mercuric chloride, was admitted to the hospital with features of multiple organ damage for specific treatment. The performed laboratory tests confirmed high levels of mercury in the blood (1051 µg/L) and urine (22,960 µg/L). Due to acute renal failure, continuous renal replacement therapy (CRRT) CVVHD Ci-Ca was initiated; the procedure was then converted to CVVHDF Ci-Ca with ultrafiltration to optimise therapy, and CytoSorb was added to the artificial kidney system on day 3. Specific antidote therapy (DMPS) was administered concurrently. The ongoing treatment resulted in a reduction in subjective complaints, a decrease in blood mercury levels to 580 µg/L, and an improvement in parenchymal organ function. CONCLUSION: In the event of poisoning with inorganic mercury compounds (mercuric chloride), continuous renal replacement therapy using the CytoSorb filter as an extracorporeal blood purification method may be considered.


Asunto(s)
Lesión Renal Aguda , Intoxicación por Mercurio , Mercurio , Femenino , Humanos , Adulto Joven , Adulto , Cloruro de Mercurio/uso terapéutico , Cloruros/uso terapéutico , Intoxicación por Mercurio/diagnóstico , Intoxicación por Mercurio/tratamiento farmacológico , Mercurio/uso terapéutico , Lesión Renal Aguda/inducido químicamente , Lesión Renal Aguda/terapia
2.
Heliyon ; 8(9): e10643, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-36164542

RESUMEN

The goal of the paper is to show how the problem of determining the Economic Order Quantity and Reorder Point could be solved with the use of a regression model. The method proposed by the authors of the paper is an alternative to the methods in which a mathematical EOQ formula is used and also to the simulation method. The intention of the authors was to find a solution which would allow, on the one hand, to obtain results as close as possible to real parameters and on the other, could be useful for decision makers in companies. With the use of a specially elaborated model, simulations have been conducted for different parameters (value, weight, demand of a commodity, logistics costs) which first proved the importance of the optimization of deliveries to a warehouse. Second, based on the results of these simulation, model regression models have been worked out and used for finding delivery quantities and reorder point. Both regression models are statistically significant, a slightly better value is obtained by the model created for the reorder point.

3.
Materials (Basel) ; 15(3)2022 Feb 07.
Artículo en Inglés | MEDLINE | ID: mdl-35161180

RESUMEN

In recent years, natural-based polymeric composites have gained the attention of researchers and the industry due to their low environmental impact and good applicational properties. A promising example of these materials is polylactide-based composites filled with linseed cake. Even though they can be characterized by reduced brittleness and enhanced crystallization rate, their applicational potential cannot be fully evaluated without knowing their tribological properties. This paper is aimed to analyze the influence of the oil contained by the filler on the mechanical and frictional properties of polylactide-based composites. Specimens of unfilled polylactide and its composites containing 10 wt % of linseed cake with different oil content were prepared by injection molding. Their microhardness was measured by the Vickers method. The softening temperature was determined by the Vicat method. The scratch resistance of the samples was tested with the loading of 10, 20 and 40 N. The coefficient of friction was evaluated by the pin-on-plate method, using CoCrMo alloy as the counter surface. It was found that the oil content in the filler does not directly influence the mechanical and tribological properties, but the composite samples present comparable hardness and lower coefficient of friction than the unfilled polymer, so they can be a good eco-friendly alternative to the unfilled polylactide when the frictional properties are an important factor.

4.
J BUON ; 25(1): 527-530, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32277679

RESUMEN

PURPOSE: To evaluate and compare plasma osteopontin (OPN, a candidate prostate cancer biomarker) levels in prostate cancer patients receiving radiotherapy or combined radiotherapy or hormone therapy. METHODS: OPN levels were determined by ELISA in 40 prostate cancer patients eligible for radiotherapy (n=18 radiotherapy alone, n=22 combined radiotherapy and hormone therapy) before the start of irradiation, during treatment, and one month after its completion. RESULTS: OPN levels were significantly higher (p=0.02) in prostate cancer patients after receiving radiotherapy compared to baseline. In a subgroup analysis, there were no differences in OPN levels before and after treatment in patients undergoing radiotherapy alone, but OPN levels were significantly higher in patients after radiotherapy with hormone therapy compared to baseline (p=0.04) and in patients during radiotherapy compared to baseline (p=0.03). CONCLUSIONS: Radiotherapy can increase plasma OPN concentrations in patients with prostate cancer, and radiotherapy may interact with hormone therapy to increase OPN concentrations. These differences suggest that OPN is worthy of further study as a predictive biomarker.


Asunto(s)
Osteopontina/efectos de los fármacos , Neoplasias de la Próstata/tratamiento farmacológico , Neoplasias de la Próstata/radioterapia , Anciano , Anciano de 80 o más Años , Humanos , Masculino , Persona de Mediana Edad , Pronóstico
5.
Biomed Mater Eng ; 30(3): 297-308, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31006657

RESUMEN

BACKGROUND: Breakage of joint arthroplasty components are rare, yet during an implant retrieval program we found several cases. OBJECTIVE: In this study we examined the components to determine the causes and mechanisms of breakage of these implants. METHODS: From our collection of 849 retrievals we selected 682 cases with metal parts (503 hip, 79 knee arthroplasties) and identified fractured components: seven hip resurfacing implants, five total hip replacement stems, one monopolar femoral head, and one modular revision femoral stem from. Implants were examined using optical and scanning electron microscopy; metallographic sections were prepared and samples of periprosthetic tissues underwent microscopic examination. RESULTS: In the resurfacing components breakage occurred in small stems placed in the femoral neck due to necrosis of femoral heads, with no metal flaws detected. Fatigue breakage of femoral stems was caused by presence of material flaws in the CoCrMo alloy, and corrosion. The monopolar head failed in fatigue fracture mechanism, breakage was initiated in an undercut near the taper connection for femoral component. The modular stem from Ti alloy sustained fatigue fracture induced by corrosion caused by debris from previously revised stem; no material flaws were detected in this sample. In most cases periprosthetic tissues had a morphology typical for aseptic loosening. CONCLUSIONS: In our series failure was caused by material flaws, presence of stress raisers and localized corrosion. Our findings indicate that sharp edges and other features which can act as stress raisers should be avoided in newly designed implants. Corrosion induced fracture of the modular Ti stem indicates the need for a detailed debridement of periprosthetic tissues during revision arthroplasties.


Asunto(s)
Prótesis de Cadera , Falla de Prótesis , Vitalio , Artroplastia de Reemplazo de Cadera/efectos adversos , Corrosión , Análisis de Falla de Equipo , Cabeza Femoral/patología , Cabeza Femoral/cirugía , Articulación de la Cadera/cirugía , Prótesis de Cadera/efectos adversos , Humanos , Diseño de Prótesis , Falla de Prótesis/efectos adversos , Vitalio/efectos adversos , Vitalio/química
6.
Urol J ; 16(2): 134-140, 2019 05 05.
Artículo en Inglés | MEDLINE | ID: mdl-30178447

RESUMEN

PURPOSE: The novel biomarkers that would identify patients at risk for relapse and metastatic spread are needed. The aim of this study was the evaluation of serum levels of osteopontin (OPN) and tumor endogenous angiogenic factors such as vascular-endothelial growth factor (VEGF), vascular-endothelial growth factor receptor 2 (VEGF R2), endostatin, angiostatin and thrombospondin 1, in prostate cancer (PC) patients. MATERIAL AND METHODS: Blood concentrations of the analyzed parameters were determined in 40 prostate cancer patients eligible for radiotherapy as well as in the control group consisted of 25 volunteers. Commercial ELISA kits were used for the analysis. RESULTS: Significantly higher levels of OPN (101.49 ng/mL vs 59.88 ng/mL; P<.001), endostatin (252.60 ng/mL vs. 223.55 ng/mL; P=.043), angiostatin (47 ng/mL vs. 13 ng/mL; P=.047), VEGF (262.1 pg/mL vs. 138.0 pg/mL; P=.056) and VEGF R2 (11188.81 pg/mL vs. 9377.50 pg/mL; P=.047) were detected in PC patients compared with the control group. In PC patients we showed a positive correlation between OPN level and TNM clinical stage(R=0.36; P=.02) and negative correlation between OPN level and hemoglobin concentration (R=-0.33; P=.04). CONCLUSION: The study showed higher levels of the angiogenic factors in PC patients compared with the control group and identified OPN as an indicator of the PC clinical stage as well as a decreased hemoglobin level.


Asunto(s)
Proteínas Angiogénicas/sangre , Biomarcadores de Tumor/sangre , Osteopontina/sangre , Neoplasias de la Próstata/sangre , Anciano , Anciano de 80 o más Años , Humanos , Masculino , Persona de Mediana Edad
7.
J BUON ; 24(6): 2570-2576, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31983134

RESUMEN

PURPOSE: The purpose of this study was to develop a method for dose distribution visualization in the case of Electron Beam Intraoperative Radiotherapy based on the images obtained in the operating room. This cannot be relied on CT images obtained before surgery due to significant tissue deformation. METHODS: The ultrasound scanning is the only method to obtain 3-dimensional (3D) reconstruction of a patient's tissue under operating room conditions. We decided to apply this modality as a background to visualize 3D dose distribution in terms of intraoperative radiotherapy (IORT). Dose distribution was obtained on the basis of dosimetric measurements carried out in the water phantom (PDD curves, transversal profiles). RESULTS: The method which has been developed in our department helps optimize the treatment. The amount of information depends strongly on the quality of the ultrasound image. We have verified the method (spatial correctness of dose painting) using commercially available phantom typically used for performance and quality assurance in ultrasound imaging (CIRS) and we noticed good correlation between 3D dose distribution and ultrasound image. CONCLUSIONS: Using up-to-date ultrasound tissue images allows better treatment optimization compared to the previous method that uses pre-surgery scans (CT or MRI). It helps optimize the angle of the beam axis and choose the beam with adequate range (energy) and avoid the risk of inaccurate irradiation of the area of interest.


Asunto(s)
Electrones/uso terapéutico , Imagenología Tridimensional/métodos , Neoplasias/diagnóstico por imagen , Fantasmas de Imagen , Planificación de la Radioterapia Asistida por Computador/métodos , Radioterapia Guiada por Imagen/métodos , Ultrasonografía/métodos , Femenino , Humanos , Masculino , Neoplasias/patología , Neoplasias/radioterapia , Dosificación Radioterapéutica
9.
Br J Radiol ; 91(1088): 20170653, 2018 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-29470136

RESUMEN

OBJECTIVE: Studies examining radiation-induced heart toxicity in breast cancer patients are inconclusive. The aim of this study was to prospectively and quantitatively asses myocardial blood flow (MBF) with, for the first time, 15O-H2O PET/CT as a marker of heart damage in irradiated breast cancer patients. METHODS: 15 breast cancer patients receiving intact breast or chest wall irradiation were included in the analysis (six with right-sided and nine with left-sided breast cancer). They underwent 15O-H2O PET/CT before radiotherapy (RT) and 2 and 8 months after RT. MBF was quantitatively assessed at rest and under stress conditions in 17 heart segments distinguished according to the American Ultrasound Association classification. Regional MBF values were derived in each of the coronary artery territories. RESULTS: MBF decreased in 53% and increased in 33% of cases 2 months after RT in both left-sided and right-sided breast cancer patients. Stress testing was more sensitive than at-rest testing, demonstrating decreased perfusion in the segments supplied by the left anterior descending coronary artery (LAD) [5.41 ± 1.74 vs 4.52 ± 1.82 ml (g*min)-1; p = 0.018], which persisted at 6 months [5.41 ± 1.74 vs 4.40 ± 1.38 ml (g*min)-1; p = 0.032] and a decrease in global heart perfusion [5.14 ± 1.49 vs 4.46 ± 1.73 ml (g*min)-1; p = 0.036]. A minimal radiation dose applied to the LAD correlated with MBF changes observed 2 months after RT (r = -0.57; p = 0.032). Radiological findings were not correlated with clinical symptoms of heart toxicity. CONCLUSION: 15O-H2O PET/CT is safe and effective for the early detection and quantitative analysis of subclinical post-RT changes in heart perfusion in breast cancer patients. The LV segments supplied by the LAD are the main site of MBF changes. A minimum radiation dose deposited in the LAD may be a predictor of radiation-induced heart toxicity. Advances in knowledge: This is the first time that 15O-H2O PET/CT has been used to assess MBF after RT and the first granular description of the distribution of blood flow changes after breast cancer RT.


Asunto(s)
Neoplasias de la Mama/fisiopatología , Neoplasias de la Mama/radioterapia , Circulación Coronaria , Corazón/diagnóstico por imagen , Corazón/efectos de la radiación , Radioisótopos de Oxígeno , Tomografía Computarizada por Tomografía de Emisión de Positrones , Agua , Adulto , Anciano , Femenino , Humanos , Persona de Mediana Edad , Tomografía Computarizada por Tomografía de Emisión de Positrones/métodos , Estudios Prospectivos , Factores de Tiempo
11.
J Mech Behav Biomed Mater ; 55: 127-139, 2015 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-26584076

RESUMEN

Data regarding in vivo performance of titanium nitride (TiN) coated prosthetic femoral heads is scarce, and available studies of older generations of implants demonstrated coating wear in vivo. That is why we conducted a retrieval analysis of 11 femoral heads (articulating in vivo for 1-56 months) with TiN film formed using physical vapor deposition (PVD), to verify if coating failure is a problem in contemporary implants. Retrieved implants were examined using scanning electron microscope, coating roughness was evaluated with a contact profilometer and adhesion was tested using a Rockwell HRC test according to VDI 3824 guideline. Although no gross failure of the TiN coating was observed in our retrievals, all implants had defects typical for PVD coatings, such as pinholes, small titanium droplets and blisters with delaminated coating. In some heads the coating was contaminated with small niobium (Nb) droplets uniformly scattered on the entire surface of the film. Presence of Nb contamination was associated with an increased number and area of other types of defects and poorer coating adhesion. In one component, subjected to multiple dislocations we found severe delamination and cracking of the coating, increased roughness and the presence of third bodies. Our results indicate, that although wear of the coating is lower than seen in older generations of implants, inconsistent quality of the TiN film among different implants indicates the need for strict monitoring of the manufacturing process.


Asunto(s)
Materiales Biocompatibles Revestidos/química , Cabeza Femoral , Prótesis de Cadera , Ensayo de Materiales , Fenómenos Mecánicos , Polietileno/química , Titanio/química , Propiedades de Superficie , Volatilización
12.
PLoS One ; 10(10): e0140917, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26468649

RESUMEN

Gliomas are common brain tumours, but obtaining tissue for definitive diagnosis can be difficult. There is, therefore, interest in the use of non-invasive methods to diagnose and grade the disease. Although positron emission tomography (PET) with 18F-fluorethyltyrosine (18F-FET) can be used to differentiate between low-grade (LGG) and high-grade (HGG) gliomas, the optimal parameters to measure and their cut-points have yet to be established. We therefore assessed the value of single and dual time-point acquisition of 18F-FET PET parameters to differentiate between primary LGGs (n = 22) and HGGs (n = 24). PET examination was considered positive for glioma if the metabolic activity was 1.6-times higher than that of background (contralateral) brain, and maximum tissue-brain ratios (TBRmax) were calculated 10 and 60 min after isotope administration with their sums and differences calculated from individual time-point values. Using a threshold-based method, the overall sensitivity of PET was 97%. Several analysed parameters were significantly different between LGGs and HGGs. However, in a receiver operating characteristics analysis, TBR sum had the best diagnostic accuracy of 87% and sensitivity, specificity, and positive and negative predictive values of 100%, 72.7%, 80%, and 100%, respectively. 18F-FET PET is valuable for the non-invasive determination of glioma grade, especially when dual time-point metrics are used. TBR sum shows the greatest accuracy, sensitivity, and negative predictive value for tumour grade differentiation and is a simple method to implement. However, the cut-off may differ between institutions and calibration strategies would be useful.


Asunto(s)
Neoplasias Encefálicas/diagnóstico por imagen , Neoplasias Encefálicas/patología , Glioma/diagnóstico por imagen , Glioma/patología , Tomografía de Emisión de Positrones , Radiofármacos , Adulto , Anciano , Biopsia , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Clasificación del Tumor , Tomografía de Emisión de Positrones/métodos , Tomografía de Emisión de Positrones/normas , Curva ROC , Reproducibilidad de los Resultados , Estudios Retrospectivos , Carga Tumoral , Adulto Joven
13.
J Ultrason ; 14(59): 393-401, 2014 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-26673805

RESUMEN

It is assumed that tactical medicine encompasses all therapeutic activities performed by a military medical service during military and humanitarian missions. Its scope is only apparently limited by the standards which, when referred to the NATO member countries, have been collected in the Joint Theater Trauma System - Clinical Practice Guidelines. The stage-structured character of medical assistance and treatment of the wounded, injured and sick patients assumes that the scope of therapeutic activities performed at each stage is limited only to essential actions. Consequently, more injured patients may be saved - those for whom life-saving activities are performed prior to their transfer to a higher level. The second level is represented by a field hospital. Its first structure is the trauma room in which a rescue team saves and qualifies the injured for further medical activities. Each injured patient undergoes an eFAST ultrasound examination which allows for a quick decision about a surgical treatment to be provided. Moreover, this technique is helpful in vascular cannulation. The authors present their own experiences with using an ultrasound examination during the work in the Field Hospital of the Polish Military Contingent in Afghanistan.

14.
Contemp Oncol (Pozn) ; 17(5): 413-20, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-24596529

RESUMEN

AIM OF THE STUDY: The aim of the study was to evaluate the effectiveness of postoperative radiotherapy in prostate cancer patients with unfavorable prognostic factors. MATERIAL AND METHODS: In the years 2002-2008, 121 consecutive prostate cancer patients underwent radical prostatectomy and postoperative radiotherapy. The median dose was 64 Gy (range: 60-72 Gy). Biochemical and clinical progression-free survival were estimated. Univariate and multivariate analyses were used to analyze clinicopathological variables associated with treatment failure. RESULTS: The median follow-up was 27 months. Three-year bPFS was 72%. On univariate analysis it was influenced by: extracapsular tumor extension (60% vs. 75%, p = 0.0232), seminal vesicles invasion (52% vs. 85%, p = 0.00041), Gleason score ≥ 7 (65% vs. 86%, p = 0.044) and the use of hormonal therapy (50% vs. 80%, p = 0.0058). On multivariate analysis bPFS was associated with: TNM stage (HR = 3.19), postoperative hormonal therapy (HR = 2.6), total irradiation dose (HR = 0.82) and the maximum pretreatment level of prostate-specific antigen (PSA) (HR = 0.95). Three-year cPFS was 84%. On univariate analysis it was influenced by: preoperative PSA level > 10 ng/ml (75% vs. 90%, p = 0.04), vascular-nerve bundles involvement (63% vs. 88%, p = 0.0031), adjacent organs infiltration (50% vs. 85%, p = 0.018) and the use of postoperative hormonal therapy (62% vs. 90%, p = 0.02). On multivariate analysis cPFS was associated with: TNM stage (HR = 2.68), postoperative hormonal therapy (HR = 3.61) and total irradiation dose (HR = 0.78). CONCLUSIONS: Postoperative radiotherapy in patients with unfavorable prognostic factors provides good biochemical and local control. Total irradiation dose and postoperative hormonal therapy are important treatment factors influencing prognosis.

15.
Otolaryngol Pol ; 66(3): 196-200, 2012.
Artículo en Polaco | MEDLINE | ID: mdl-22748681

RESUMEN

INTRODUCTION: The aim of the work was to assess early complications of Griggs percutaneous tracheotomy in the own material. MATERIAL AND METHODS: The study covered 155 patients aged 17-88, including 36 women and 119 men. The patients were treated at the Department of Anaesthesiology and Intensive Therapy between 2006-2010. They underwent Griggs percutaneous tracheostomy by a laryngologist or a trained anaesthesiologist. Each surgical procedure was conducted with the use of Portex Blue Line Ultra Percutaneous Tracheotomy Kit (Smiths Medical Co., USA), the trachea was intubated while the patient was under general anaesthesia with propofol, fentanyl and relaxation with atracurium. RESULTS: The studied material revealed Griggs percutaneous tracheotomy complications in 26 patients (16.8%), in which 11 patients (7.1%) presented complications within the perioperative period while 15 patients (9.7%) reported early complications. Haemorrhage, usually not very profuse, occurred 7 times (4.6%), mainly in tracheopunction, and was the most often perioperative complication. Moreover, in the perioperative period, 3 patients (1.9%) had trachea identifications difficulties, which required tracheopunction many a time, and 1 patient (0.65%) encountered sudden circulatory arrest with asystolia and effective CPR. In the early postoperative period after Griggs percutaneous tracheotomy, the most common complication was haemorrhage in the operative twenty-four hours, which was noted in 10 patients (6.5%). Among other adverse complications were found: infection of the tissues near the tracheostomal region in 3 patients (1.9%), subcutaneous oedema in 1 patient (0.65%), accidental removing the tube from an unformed tracheostoma in 1 patient (0.65%). CONCLUSIONS: In the studied material, complications after Griggs percutaneous tracheotomy amounted to 16.8%, of which 7.1% occurred in the perioperative period while 9.7% were early complications, mainly light bleeding. This may prove good preparation of the surgical team for the surgical procedures.


Asunto(s)
Hemorragia/epidemiología , Infecciones/epidemiología , Complicaciones Posoperatorias/epidemiología , Enfermedades de la Tráquea/epidemiología , Traqueotomía/métodos , Traqueotomía/estadística & datos numéricos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Causalidad , Femenino , Hemorragia/etiología , Humanos , Infecciones/etiología , Masculino , Persona de Mediana Edad , Complicaciones Posoperatorias/etiología , Enfermedades de la Tráquea/etiología , Traqueotomía/efectos adversos , Adulto Joven
16.
Int J Occup Saf Ergon ; 18(2): 233-43, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22721541

RESUMEN

The aim of the study was to investigate the possibility of using infrared (IR) thermography for assessing muscle fatigue during low effort. Three tests at constant levels of load 5, 15 and 30% of maximum voluntary contraction (MVC) lasting 5 min each were performed on a group of 10 men. Temperature and electromyographic (EMG) signal were registered from biceps brachii (BB). Analysis focused on the influence of load on the values and changes in time of muscle temperature. Correlations between temperature and EMG parameters (RMS, MPF and MF) were also analysed. Constant load sustained during the tests resulted in an increase in the temperature of BB. There were statistically significant correlations between temperature and EMG parameters for most subjects. Results of the study suggest that IR thermography can be an alternative or supplementary method for assessing muscle fatigue at low levels of contraction.


Asunto(s)
Temperatura Corporal , Fatiga Muscular , Músculo Esquelético/fisiología , Termografía , Adulto , Electromiografía , Humanos , Masculino , Adulto Joven
17.
Contemp Oncol (Pozn) ; 16(6): 491-7, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-23788934

RESUMEN

Prostate cancer is one of most frequent malignant tumours at men. The androgen-deprivation therapy is the part of cancer treatment. It could be used both in the early stage of prostate cancer and in the bone metastates. From this reason the antiandrogen drugs waste systematically grows. Unfortunately androgen-deprivation therapy has numerous side effects such as: the inferior quality of live, sexual disturbances, the fatigue, the anaemia, the bone mineral density loss and the increase of the risk of breaks the bone, the increase of body mass, insulinresistance, hypercholesterolemia, the increase risk of cardiac disorders. The aim of this article is the introduction of the reader with possibly complications androgen-deprivation therapy and with possibilities in diagnosis and treatment.

18.
J Phys Chem A ; 114(30): 7903-11, 2010 Aug 05.
Artículo en Inglés | MEDLINE | ID: mdl-20666538

RESUMEN

An infrared camera was used for the first time to monitor the progress of traveling fronts in oscillatory chemical reactions, taking the Belousov-Zhabotinsky (BZ) reaction as the test system. The experiments involved comparative visual imaging and infrared thermography measurements for the thin-layer of the BZ solution in the Petri dish, including both aqueous and gel media, the latter one hindering the convection. Infrared thermography experiments that supply information on the temperature distribution at the solution surface were compared with the bulk temperature variations of the stirred solution with BZ reaction, measured simultaneously with the oscillatory variations of the Pt electrode potential. The experimentally observed correlation between the ferroin catalyst concentration and the temperature distribution was compared with the results of numerical modeling of these distributions in 2-D reactor space, based on the classical Oregonator. Analogous experiments were performed for the oscillatory oxidation of thiocyanates with hydrogen peroxide, catalyzed with Cu(2+) ions, in search of factors causing the development of traveling fronts, previously reported. The inhomogeneous distribution of the free surface temperature that could contribute to surface instabilities was found. Also, periodical increase and decrease in temperature of solution surface was reported. This was interpreted as periodically predominating cooling of the surface in contact with the surroundings because for the bulk, thermally isolated stirred solution, the temperature monotonically increases. In terms of our nine-variable kinetic model of this system, it was possible to identify the reaction steps responsible for the experimentally observed temperature dynamics and ascribe the appropriate heat effects to them. Our results constitute the first contribution to the thermochemical characteristics of the H(2)O(2)-SCN(-)-OH(-)-Cu(2+) oscillator.

19.
J Contemp Brachytherapy ; 1(2): 92-96, 2009 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-27795718

RESUMEN

PURPOSE: To determine the clinical and dosimetric factors that predict prostate-specific antygen (PSA) bouncing following brachytherapy HDR and three-dimensional conformal radiation therapy (3D-CRT) for prostate cancer patients. MATERIAL AND METHODS: The evaluated population consisted of 121 prostate cancer patients with a minimum of 5 years of follow-up and at least 6 post-treatment PSA levels. All patients were treated using 3D-CRT combined with brachytherapy HDR. A bounce was defined as a PSA rise of ≥ 0.2 ng/ml above the nadir followed by a subsequent 120 decline of ≥ 0.2 ng/ml. The evaluated clinical factors included: patient age, Gleason score, maximum initial pretreatment PSA value (iPSAmax), clinical stage, prostate volume, median time to PSA nadir, median PSA nadir value and patient follow-up in months. The dosimetric factors evaluated included the percentage of the prostate volume receiving 100% (V100), 150% (V150) and 200% (V200) of the prescribed minimal peripheral dose. RESULTS: Statistically significant predictive factors for PSA bounce were age, V100, V150, V200, iPSAmax and median time to PSA nadir. Logistic regression model for multivariate analysis revealed that only age, iPSAmax and V200 were statistically significant predictors for PSA bounce. There were not statistical differences between median nadir among patients who exhibited a PSA bounce and did not but non-bouncer reached PSA nadir earlier than bouncer, respectively median time was 12.1 vs. 17.2 months. CONCLUSIONS: PSA bouncing occurs in approximately a one third (1/3) of patients treated with 3D-CRT and brachytherapy HDR. Bouncing is associated with age, higher pretreatment PSA level and increased V200 factor.

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