Continuous H-B-E fermentation by Clostridium carboxidivorans: CO vs syngas.

Leveraging renewable carbon-based resources for energy and chemical production is a promising approach to decrease reliance on fossil fuels. This entails a thermo/biotechnological procedure wherein bacteria, notably Clostridia, ferment syngas, converting CO or CO2 + H2 into Hexanol, Butanol and Ethanol (H-B-E fermentation). This work reports of Clostridium carboxidivorans performance in a stirred tank reactor continuously operated with respect to the gas and the cell/liquid phases. The primary objective was to assess acid and solvent production at pH 5.6 by feeding pure CO or synthetic syngas under gas flow differential conditions. Fermentation tests were conducted at four different dilution rates (DL) of the fresh medium in the range 0.034-0.25 h-1. The fermentation pathways of C. carboxidivorans were found to be nearly identical for both CO and syngas, with consistent growth and metabolite production at pH 5.6 within a range of dilution rates. Wash-out conditions were observed at a DL of 0.25 h-1 regardless of the carbon source. Ethanol was the predominant solvent produced, but a shift towards butanol production was observed with CO as the substrate and towards hexanol production with synthetic syngas. In particular, the maximum cell concentration (0.5 gDM/L) was obtained with pure CO at DL 0.05 h-1; the highest solvent productivity (60 mg/L*h of total solvent) was obtained at DL 0.17 h-1 by using synthetic syngas as C-source. The findings highlight the importance of substrate composition and operating conditions in syngas fermentation processes. These insights contribute to the optimization of syngas fermentation processes for biofuel and chemical production.

Microbiological analysis of autologous bone particles obtained by low-speed drilling and treated with different decontamination agents.

The aim of this study was to compare the effectiveness of three agents - two antibiotics (amoxicillin and clindamycin) and an antiseptic (chlorhexidine) - to decontaminate bone grafts obtained by low-speed drilling. The study included 248 bone tissue samples harvested from 62 patients by low-speed drilling before dental implant placement. Each of four samples obtained from every patient was dropped, using a sterile instrument, into a sterile tube containing a 500-µl solution of 400µg/mL amoxicillin, 150µg/mL clindamycin, 0.12% chlorhexidine, or physiological saline for 1min. The number of colony-forming units (CFU) was determined at 48h of culture. The use of clindamycin, amoxicillin, or chlorhexidine as decontaminant for 1min significantly reduced the CFU count when compared to physiological saline (control agent). In both anaerobic and CO2-rich atmospheres, significant differences in CFU/mL were found between the control and chlorhexidine groups (P<0.001), control and amoxicillin groups (P<0.001), control and clindamycin groups (P<0.001), chlorhexidine and amoxicillin groups (P<0.0001), and chlorhexidine and clindamycin groups (P<0.0001). In conclusion, clindamycin had the highest decontaminating effect on bone particles obtained by low-speed drilling, followed by chlorhexidine and amoxicillin. Clindamycin may therefore be a valid alternative option for the routine decontamination of intraoral bone grafts.

An alternative approach to GTV margin determination in stereotactic body radiotherapy.

PURPOSE: This study aims to estimate a realistic margin in stereotactic body radiotherapy (SBRT) through examining the determination uncertainties of gross tumour volume (GTV). METHODS: Three computed tomography (CT) scans were performed on each patient in different sessions as a treatment simulation. Registration of the different CT image sets was based on the fiducial marks from two stereotactic guides. GTV was defined in each one of them, as well as both the encompassing (UNI) and overlapping (INT) volumes. This protocol was altered following imaging guided radiotherapy (IGRT) implementation, so tumour displacements could be corrected for. The patient was scanned without repositioning solely considering tumour intrafraction variations. In addition, isocentre and dimension variations were obtained for each patient and cohort. A Monte Carlo code was developed to simulate tumour volume, considering them as ellipsoids in order to study their behaviour. Lastly, the equivalent radius (R eq) was defined for each of these volumes, experimental and simulated, and both and values were derived by simple linear regression to the mean value . RESULTS: The global margin M can be defined as this systematic error plus an additional residual random uncertainty, with values M = 3.4 mm for Body Frame, M = 2.3 mm for BodyFIX and M = 2.1 mm without repositioning. The experimental results obtained are in good agreement with simulated values, validating the use of the Monte Carlo code to calculate a margin formula. CONCLUSIONS: Introducing IGRT is not enough to obtain a zero margin; consequently, the safety margin, dependent on tumour shape and size dispersion, can be evaluated using this formulation.

Topographic characterisation of dental implants for commercial use.

BACKGROUND: To characterize the surface topography of several dental implants for commercial use. MATERIAL AND METHODS: Dental implants analyzed were Certain (Biomet 3i), Tissue Level (Straumann), Interna (BTI), MG-InHex (MozoGrau), SPI (Alphabio) and Hikelt (Bioner). Surface topography was ascertained using a confocal microscope with white light. Roughness parameters obtained were: Ra, Rq, Rv, Rp, Rt, Rsk and Rku. The results were analysed using single-factor ANOVA and Student-Neuman-Keuls (p<0.05) tests. RESULTS: Certain and Hikelt obtained the highest Ra and Rq scores, followed by Tissue Level. Interna and SPI obtained lower scores, and MG-InHex obtained the lowest score. Rv scores followed the same trend. Certain obtained the highest Rp score, followed by SPI and Hikelt, then Interna and Tissue Level. MG-InHex obtained the lowest scores. Certain obtained the highest Rt score, followed by Interna and Hikelt, then SPI and Tissue Level. The lowest scores were for MG-InHex. Rsk was negative (punctured surface) in the MG-InHex, SPI and Tissue Level systems, and positive (pointed surface) in the other systems. Rku was higher than 3 (Leptokurtic) in Tissue Level, Interna, MG-InHex and SPI, and lower than 3 (Platykurtic) in Certain and Hikelt. CONCLUSIONS: The type of implant determines surface topography, and there are differences in the roughness parameters of the various makes of implants for clinical use.

PET/CT image registration: preliminary tests for its application to clinical dosimetry in radiotherapy.

The quality of dosimetry in radiotherapy treatment requires the accurate delimitation of the gross tumor volume. This can be achieved by complementing the anatomical detail provided by CT images through fusion with other imaging modalities that provide additional metabolic and physiological information. Therefore, use of multiple imaging modalities for radiotherapy treatment planning requires an accurate image registration method. This work describes tests carried out on a Discovery LS positron emission/computed tomography (PET/CT) system by General Electric Medical Systems (GEMS), for its later use to obtain images to delimit the target in radiotherapy treatment. Several phantoms have been used to verify image correlation, in combination with fiducial markers, which were used as a system of external landmarks. We analyzed the geometrical accuracy of two different fusion methods with the images obtained with these phantoms. We first studied the fusion method used by the PET/CT system by GEMS (hardware fusion) on the basis that there is satisfactory coincidence between the reconstruction centers in CT and PET systems; and secondly the fiducial fusion, a registration method, by means of least-squares fitting algorithm of a landmark points system. The study concluded with the verification of the centroid position of some phantom components in both imaging modalities. Centroids were estimated through a calculation similar to center-of-mass, weighted by the value of the CT number and the uptake intensity in PET. The mean deviations found for the hardware fusion method were: deltax/ +/-sigma = 3.3 mm +/- 1.0 mm and /deltax/ +/-sigma = 3.6 mm +/- 1.0 mm. These values were substantially improved upon applying fiducial fusion based on external landmark points: /deltax/ +/-sigma = 0.7 mm +/- 0.8 mm and /deltax/ +/-sigma = 0.3 mm 1.7 mm. We also noted that differences found for each of the fusion methods were similar for both the axial and helical CT image acquisition protocols.

Frequency of the VO2max plateau phenomenon in world-class cyclists.

We aimed to determine the frequency of the VO2max plateau phenomenon in top-level male professional road cyclists (n = 38; VO2max [mean +/- SD]: 73.5 +/- 5.5 ml.kg(-1).min(-1)) and in healthy, sedentary male controls (n = 37; VO2max: 42.7 +/- 5.6 ml.kg(-1).min(-1)). All subjects performed a continuous incremental cycle-ergometer test of 1-min workloads until exhaustion. Power output was increased from a starting value of 25 W (cyclists) or 20 W (controls) at the rate of 25 W.min(-1) (cyclists) or 20 W.min(-1) (controls) until volitional exhaustion. We measured gas-exchange and heart rate (HR) throughout the test. Blood concentrations of lactate (BLa) were measured at end-exercise in both groups. We defined maximal exercise exertion as the attainment of a respiratory exchange rate (RER) >or= 1.1; HR > 95 % age-predicted maximum; and BLa > 8 mmo.l(-1). The VO2max plateau phenomenon was defined as an increase in two or more consecutive 1-min mean VO2 values of less than 1.5 ml.kg(-1).min(-1). Most cyclists met our criteria for maximal exercise effort (RER > 1.1, 100 %; 95 % predicted maximal HR [HRmax], 82 %; BLa > 8 mmol.l(-1), 84 %). However, the proportion of cyclists attaining a V.O (2max) plateau was considerably lower, i.e., 47 %. The majority of controls met the criteria for maximal exercise effort (RER > 1.1, 100 %; predicted HRmax, 68 %; BLa > 8 mmol. l(-1), 73 %), but the proportion of these subjects with a VO2max plateau was only 24 % (significantly lower proportion than in cyclists [p < 0.05]). Scientists should consider 1) if typical criteria of attainment of maximal effort are sufficiently stringent, especially in elite endurance athletes; and 2) whether those humans exhibiting the VO2max plateau phenomenon are those who perform an absolute maximum effort or there are additional distinctive features associated with this phenomenon.

Antigenic profile of osteoblasts present in human bone tissue sections.

The antigenic profile of human osteoblasts was previously analyzed by our group using primary cultures as study samples. These studies suggested a novel functional approach to this cell population. Osteoblasts have a characteristic antigenic profile and share antigens in common with other cell populations that also originate in the bone marrow. Some of the detected antigens are constitutively expressed, while others are modulated by different factors and/or cytokines. The aim of the present study was to analyze the antigens present in osteoblasts in vivo, since the presence of certain biomolecules in fetal bovine serum may modulate the antigenic expression, compromising the results. For this purpose, human bone tissue sections were analyzed with a wide panel of mAbs and using the immunoperoxidase technique. CD10, CD44 and alkaline phosphatase antigens and IL-12, IL-18 and IFNgamma cytokines were detected in osteoblasts in the bone tissue. However, CD80 and HLA-DR antigens were not found in all samples and when present their expression was weak. The expression of CD54 antigen was moderate or weak. These results allow data obtained by the primary culture of osteoblast-like cells to be endorsed.

[Four-year results after lung volume reduction surgery for emphysema]. / Resultados a los 4 años de la cirugía de reducción de volumen en el enfisema.

OBJECTIVES: While the short-term results of lung volume reduction surgery are known, follow-up over several years has not often been described. The purpose of the present study was to describe results in terms of functional improvement, dyspnea, quality of life, and mortality over a 4-year period in patients with advanced emphysema. PATIENTS AND METHODS: Fourteen successive patients were enrolled between 1996 and 2000 and studied prospectively for 4 years. All patients served as their own controls and initially received pulmonary rehabilitation and medication. Preoperative data were used as baseline and were compared to postoperative data over 4 years. The data analyzed were: functional improvement (forced expiratory volume in 1 second [FEV1]), quality of life, dyspnea, and patient loss due to death or referral to a lung transplantation program. RESULTS: Patients with advanced emphysema (mean FEV1 [SD]: 22.8% [11%] of predicted) were studied. Postoperative mortality was 14%. Overall mortality (postoperative plus deaths due to respiratory insufficiency) was 28% at 1 year and 35% at 4 years. Two patients died of cancer and 5 were referred for transplantation. At 3 months, FEV1 had improved more than 15% in 9 patients (64%); the improvement was maintained in 43% of patients at 1 year and 7% at 4 years. Improvement in dyspnea paralleled improvement in FEV1. Overall, at 3 months mean FEV1 had improved 41.9% (68%), transitional dyspnea index 2.7 (3), and quality of life questionnaire score 1 (0.9). Thus, improvements were considerable, but there was great variation. Preoperative mean decrease in FEV1 was 50 (32) mL/y, and postoperative decrease 194 (70) mL/y. CONCLUSIONS: With the inclusion criteria used, there was considerable variation in the results. Significant overall functional improvement was maintained in 50% of the patients 1 year following surgery and in 7% 4 years after surgery. Given such results, together with a surgical mortality rate of 14% and overall mortality of 28% in the first year, we believe that the criteria for using lung reduction surgery should be revised.

[Body mass, dyspnea, and quality of life as success predictors in emphysema surgery for reduction of pulmonary volume]. / Masa corporal, disnea y calidad de vida como predictores de éxito en la cirugía de reducción de volumen en el enfisema.

OBJECTIVES: Lung volume reduction surgery has recently been proposed as a palliative treatment for advanced emphysema. Some patients improve and others remains the same, being debated at this time the factors that predict improvement. The purpose of this work is to find predictive factors for positive response in patients operated with this surgery. MATERIAL AND METHODS: Patients with positive response (7 patients) and patients without positive response (5 patients) have been compared in our series of lung volume reduction surgery (12 patients). Positive response to surgery was defined as Delta FEV1 > or = 15%, dyspnea transitional index (Mahler scale) > or = 3, and improvement in the scoring surgery of quality of life for chronic respiratory disease questionnaire (Guyatt and Güell) > or = 1.5 3 months after the surgery. Basal values of FEV1, FEF50/FIF50%, hyperinsufflation degree, heterogeneity, PaO2, PaCO2, type of surgery, body mass index (BMI), dyspnea basal index (DBI) and quality of life questionnaire score (QLQS). RESULTS: Patients without and with positive response were different only because their baseline BMI, DBI and QLQS were lower. Other parameters studied (although the population was rather homogeneous) did not show significant differences between the two groups. CONCLUSIONS: Patients with higher subjective problems (dyspnea and quality of life) and more malnourished are those with less benefit from surgery for pulmonary volume reduction.

Seguimiento de la frecuencia cardiaca y la presión parcial de oxígeno durante la cirugía bucal / Follow up of heart rate and oxygen partial pressure during oral surgery

Se hicieron mediciones de la frecuencia cardiaca y la presión parcial de oxígeno en sangre a un grupo de 29 pacientes durante la cirugía bucal. El objetivo del estudio era comprobar si había diferencias estadísticas entre los datos obtenidos en cada momento quirúrgico. Aplicando el test de student para muestras apareadas se obtuvieron los siguientes resultados:1.-La frecuencia cardiaca se elevó de manera significativa tras la anestesia y se mantuvo durante el despegamiento. Volvió a descender durante la osteotomía, manteniéndose durante la sutura y en el alta. En estos momentos no había diferencias con el momento inicial.2.-La presión parcial de oxígeno en sangre permaneció casi constante en cada tiempo de la cirugía bucal, y no hubo variaciones que pudieran ser atribuibles a un momento específico de la misma (AU)

Measures of heart rate and oxygen partial pressure were made in a group of 29 patients during oral surgery. The aim of the study was to compare data coming from every surgical moment by statistical methods. By using student test for coupled samples the next results were found: 1. - Heart rate increased significantly after anesthesia and went on while separating of the flap. After that, it decreased during osteotomy and didn't show considerable changes during the closing of the wound and the discharging of the patient. At this point , there were not differences compared with the starting moment. 2. - Oxygen partial pressure in blood remained almost constant while the oral surgery and there were not variations that could be Iinked to an specific stage of the ongoing surgery (AU)

Relation of patient and surgical variables to postoperative pain and inflammation in the extraction of third molars.

OBJECTIVES: An analysis is made of the influence of patient and surgical variables upon the postoperative pain and swelling normally associated with third molar extractions. STUDY DESIGN: The following patient variables were considered in a series of 150 individuals subjected to third molar extraction: sex, age, and dimensions of neurotic personality trait and extroversion (based on the Eysenck Personality Inventory, EPI). The corresponding surgical intervention parameters were: duration, ostectomy degree, dental sectioning and number of sutures. Pain was scored on a visual analog scale (VAS) 0, 8, 24, 43 and 48 hours after surgery, while inflammation was rated by means of a verbal response scale (VRS) 48 hours after extraction. RESULTS: Multivariate analysis showed postextraction pain to be mainly related to patient age and the number of sutures on the day of the operation, and to swelling over the subsequent days. A less important relation was observed with patient sex and the dimensions of neuroticism and extroversion. CONCLUSIONS: In conclusion, older patients and those subjected to extractions involving a greater number of sutures refer the most intense pain. In turn, patients with increased intensity pain also present greater inflammation.

Importancia de los índices periodontales en la evaluación de los implantes osteointegrados / Importance of periodontal indices in the evaluation of osseointegrated implants

El objetivo del estudio es conocer la relación existente entre la tasa de fracaso de una muestra de implantes recubiertos de hidroxiapatita (H.A.) y los parámetros periodontales del paciente; así como el grado de asociación entre estos últimos. La muestra está formada por 52 pacientes, a los que hemos colocado 158 implantes recubiertos de H.A. (Integral de Calcitek), que han sido revisados a los tres años de su colocación. El fracaso de los implantes se ha establecido según los criterios de SCHNITMANY SHULMAM de 1979.El estudio realizado es observacional analítico retrospectivo de seguimiento, a través del cual se evalúa la evolución clínica y radiológica de los implantes; resultando que la recesión periimplante medida en vestibular, lingual, mesial y distal de cada fijación es el único parámetro periodontal asociado al fracaso del implante (P= 0.008). La reabsorción ósea y la recesión periimplante se asocian de forma significativa (P < 0.05); así como la profundidad de sondaje lo hace con el índice de gingivitis en todas sus posiciones, y con el índice de placa en posición lingual. Hemos hallado una correlación positiva entre estos dos índices r=0.519, P<0.01 de forma que al aumentar uno lo hace el otro y viceversa. Podemos concluir que la aparición de recesión alrededor de un implante aumenta las probabilidades de que éste fracase. Existe además una correlación positiva entre el índice de gingivitis, de placa y la profundidad de bolsa, lo que indica la salud del surco gingival pero no las probabilidades de éxito del implante (AU)

The aim of this study was to determine, firstly,the relation between the failure of a sample of hydroxyapatite-coated implants (HA) and the periodontal parameters of the patient, and secondly, the degree of association between such parameters. The sample was comprised of 52 patients and 158 H.A. coated implants (Integral® by Calcitek), which were revised three years after their insertion. Implant failure was determined according to the criteria of Schnitman and Shulman (1979). A retrospective analytical observational follow-up study was carried out, by means of which the clinical and radiological evolution of the implants was determined. It was found that the peri-implant recession measured facial, lingual, mesial and distal from each implant is the only periodontal parameter associated with the failure of the implant (p=0.008). Bone resorption and periimplant recession were significantly associated (p<0.05),as was probe depth with the gingivitis index in all positions and with the plaque index in the lingual position. A positive correlation was found between the latter two indices (r=0.519; p<0.01). It may be concluded that the appearance of recession around an implant increases the probability of its failure. There was also a positive correlation between the gingivitis index, the plaque index and pocket depth, which is indica tive of the state of the gingival sulcus but not of the success rate of the implant (AU

Sustitutos óseos: el papel de los biomateriales en cirugía bucal y maxilofacial / Osseus substitutes: The biomaterials' role in oral and maxillofacial surgery

Para este trabajo, nos hemos planteado utilizar las propiedades más significativas de cada material, con el objetivo de obtener una mezcla que pueda ser útil para la regeneración ósea. Igualmente, con ello, tratamos de evitar la toma sistemática de grandes cantidades de injerto autógeno, e incluso prescindir de él. Con este propósito hemos incluido un total de 15 pacientes que presentaban algún tipo de cavidad o defecto óseo, los cuales fueron tratados con diferentes materiales: hueso autógeno, polvo de cortical desmineralizado e hidroxiapatita (HA), en diferentes combinaciones. El hueso autólogo es esencial para el éxito de la regeneración del defecto óseo, pero otros factores importantes deben ser también considerados (AU)

Expression of molecules involved in antigen presentation and T cell activation (HLA-DR, CD80, CD86, CD44 and CD54) by cultured human osteoblasts.

BACKGROUND: Osteoblasts express the CD44 antigen and HLA class II antigens, molecules which, together with other costimulatory molecules such as CD80, CD86, and CD54, are involved in antigen presentation and T cell activation. The aim of this study was to investigate the expression of these molecules in human osteoblasts. METHODS: Human osteoblastic cells obtained from samples of normal bone obtained during mandibular osteotomy were isolated, maintained in culture, and characterized. The identity of the cells was confirmed by their alkaline phosphatase activity and their capacity to produce osteocalcin. Flow cytometry was used to examine the expression HLA-DR, CD80, CD86, CD44, and CD54 molecules involved in immune activities. RESULTS: We detected the expression of CD10, CD44, and HLA-DR antigens, molecules involved in antigen presentation in cultured osteoblastic cells. Although the cells were negative for CD45, the leukocyte common antigen and CD14 (an antigen detected on macrophages), they expressed CD54, CD80, and CD86 antigens, which are also involved in the mechanisms of antigen presentation to and activation of T cells. CONCLUSIONS: Our results suggest that osteoblastic cells or a subpopulation of these cells may have immune functions in bone. Further studies in which immune functions are assessed will be needed to test this hypothesis.