Empiric antibiotics for community-acquired pneumonia in adult patients: a systematic review and a network meta-analysis.

OBJECTIVE: The main aim of this network meta-analysis is to identify the empiric antibiotic (Em-ATB) with the highest probability of being the best (HPBB) in terms of (1) cure rate and (2) mortality rate in hospitalised patients with community acquired pneumonia (CAP) . METHOD: Inclusion criteria: (1) adult patients (>16 years old) diagnosed with CAP that required hospitalisation; (2) randomised to at least two different Em-ATBs, (3) that report cure rate and (4) are written in English or Spanish. EXCLUSION CRITERIA: (1) ambiguous antibiotics protocol and (2) published exclusively in abstract or letter format. DATA SOURCES: Medline, Embase, Cochrane and citation reviews from 1 January 2000 to 31 December 2018. Risk of bias: Cochrane's tool. Quality of the systematic review (SR): A MeaSurement Tool to Assess systematic Reviews-2. Certainity of the evidence: Grading of Recommendations Assessment, Development and Evaluation. STATISTICAL ANALYSES: frequentist method performed with the 'netmeta' library, R package. RESULTS: 27 randomised controlled trials (RCTs) from the initial 41 307 screened citations were included. Regarding the risk of bias, more than one quarter of the studies presented low risk and no study presented high risk in all domains. The SR quality is moderate. For cure, two networks were constructed. Thus, two Em-ATBs have the HPBB: cetaroline 600 mg (two times a day) and piperacillin 2000 mg (two times a day). For mortality, three networks were constructed. Thus, three Em-ATBs have the HPBB: ceftriaxone 2000 mg (once a day) plus levofloxacin 500 (two times a day), ertapenem 1000 mg (two times a day) and amikacin 250 mg (two times a day) plus clarithromycin 500 mg (two times a day). The certainity of evidence for each results is moderate. CONCLUSION: For cure rate, ceftaroline and piperaciline are the options with the HPBB. However, for mortality rate, the options are ceftriaxone plus levofloxacin, ertapenem and amikacin plus clarithromycin. It seems necessary to conduct an RCT that compares treatments with the HPBB for each event (cure or mortality) (CRD42017060692).

COVID-19 and other viruses: Holding back its spreading by massive testing.

The experience of Singapore and South Korea makes it clear that under certain circumstances massive testing is an effective way for containing the advance of the COVID-19. In this paper, we propose a modified SEIR model which takes into account tracing and massive testing, proving theoretically that more tracing and testing implies a reduction of the total number of infected people in the long run. We apply this model to the spreading of the first wave of the disease in Spain, obtaining numerical results. After that, we introduce a heuristic approach in order to minimize the COVID-19 spreading by planning effective test distributions among the populations of a region over a period of time. As an application, the impact of distributing tests among the counties of New York according to this method is computed in terms of the number of saved infected individuals.

PRDM15 Is Associated with Risk of Chronic Obstructive Pulmonary Disease in a Rural Population in Chile.

BACKGROUND: Genome-wide association studies (GWAS) have accelerated our understanding of the genetic underpinnings of chronic obstructive pulmonary disease (COPD); however, GWAS populations have typically consisted of European descent, with ∼1% of Latin American ancestry. OBJECTIVE: To overcome this limitation, we conducted a GWAS in a rural Chilean population with increased COPD risk to investigate genetic variation of COPD risk in this understudied minority population. METHOD: We carried out a case-control study of 214 COPD patients (defined by the GOLD criteria) and 193 healthy controls in Talca, Chile. DNA was extracted from venous blood and genotyped on the Illumina Global Screening Array (n = 754,159 markers). After exclusion based on Hardy-Weinberg equilibrium (p ≤ 0.001), call rates (<95%), and minor allele frequencies (<0.5%) in controls, 455,564 markers were available for logistic regression. RESULTS: PRDM15 rs1054761 C allele (p = 2.22 × 10-7) was associated with decreased COPD risk. Three PRDM15 SNPs located on chromosome 21 were significantly associated with COPD risk (p < 10-6). Two of these SNPs, rs1054761 and rs4075967, were located on a noncoding transcript variant region of the gene. CONCLUSION: PRDM15 overexpression may play a role in the B-cell dysregulation in COPD pathogenesis. To the best of our knowledge, the association between PRDM15 and COPD risk was not previously found in GWAS studies in largely European populations, highlighting the importance of investigating novel variants associated with COPD risk among ethnically diverse populations.

Medium-long term effects of saline reclaimed water and regulated deficit irrigation on fruit quality of citrus.

BACKGROUND: Non-conventional water sources and water-saving techniques can be valuable in semi-arid regions, although their long-term effects on citrus quality are little known. This study evaluated the effects of irrigation with two sources, transfer water (TW) and reclaimed water (RW), combined with two irrigation strategies, full irrigation (FI) and regulated deficit irrigation (RDI), on fruit quality of mandarins and grapefruits during eight growth seasons. RESULTS: Reclaimed water irrigation in mandarin, without water restriction, influenced maturity index (MI) less than TW-FI, because titratable acidity (TA) increased to a greater degree than soluble solid contents (SSC). Nevertheless, juice quality standards were satisfied. Regardless of the irrigation treatment (FI or RDI), a trend towards increasing fruit weight was also detected with RW. In grapefruit, its rootstock (Citrus macrophylla) enhanced salinity resilience with respect to the rootstock of mandarin ('Carrizo' citrange) and, hence, MI was not affected by RW. The RDI strategy, without saline stress (TW-RDI), increased, to a similar degree, both SSC and TA in mandarin fruit, not affecting the MI. In grapefruit, the water stress of RDI did improve the MI due to the TA did not change and SSC increased significantly, the TA did not change. The combination of both strategies, RW-RDI, decreased the MI only in some years because TA increased proportionally more than SSC in mandarin. CONCLUSIONS: The medium- and long-term feasibility of using RW and RDI to irrigate citrus was demonstrated. However, they must be performed cautiously and with appropriate management to avoid damaging fruit quality as a result of phytotoxic elements. © 2019 Society of Chemical Industry.

Biopesticide and formulation processes based on starch industrial wastewater fortified with soybean medium.

The aim of this study was to produce Bacillus thuringiensis-based biopesticide using starch-producing industry wastewater (SIW) fortified with soybean medium and optimize the formulated product using different adjuvants. This study was necessary as low endotoxin concentration is obtained in formulated biopesticide when SIW alone is used as fermentation medium. The fermentation runs were conducted using SIW alone and SIW fortified with 25% soybean (w/v) medium in 2000 L and 150 L bioreactor, respectively. SIW supplemented with soybean medium showed an increase in cell count (from 1.95 × 108 to 1.65 × 109 CFU mL-1), spore synthesis (from 1.5 × 108 to 1.35 × 109 CFU mL-1) and endotoxin concentration (from 436 to 1170 µg mL-1) when compared to SIW medium alone. The fermented broth was concentrated using continuous centrifugation and adjuvants were added for biopesticide formulation in order to enhance its resistance against UV rays and rainfastness. Entomotoxicity of the formulation produced using fermented broth of SIW fortified with soybean (38,000 IU µL-1) was higher than that obtained by SIW medium alone (21,000 IU µL-1), commercial biopesticide Foray 76B (20,000 IU µL-1) and Btk sander's (12,500 IU µL-1).

Feasibility, results and endoscopic requirements of the Elipse® swallowable intragastric balloon: initial experience.

BACKGROUND: the Elipse® intragastric balloon (EIGB) is a swallowable capsule that is filled under x-ray control. After 16 weeks, its self-releasing valve is degraded and the balloon is deflated and excreted naturally, without endoscopy. The aim of this study was to assess the feasibility of EIGB and its efficacy, duration, safety and endoscopic requirements. METHODS: this is a prospective, descriptive, non-randomized study of the first patients enrolled for EIGB. An x-ray was systematically performed after placement to ensure the correct filling of the balloon. The balloon duration was determined according to its excreted visualization or by x-ray/ultrasound. The efficacy, tolerance, adverse events and their resolution outcome (endoscopic requirements), as well as the final satisfaction degree at 16 weeks, were analyzed. RESULTS: the study included 30 patients with a basal mean weight and body mass index (BMI) of 83.3 ± 10.7 kg and 30.6 ± 2.7 kg/m². All subjects swallowed the capsule with correct x-ray control. The mean weight loss was 11.2 ± 5.5 kg (12.1 ± 5.8% of total weight loss [TWL], 64.7 ± 25% of excess weight loss [EWL]), with a weight loss > 10% in 80% of patients (p < 0.05) after four months. Early elimination of the balloon with an insufficient duration (< 12 weeks) was observed in 2/24 patients (8.3%). There was an acceptable tolerance in 80%. With regard to adverse effects, one balloon was vomited up, there was one intolerance and the balloon was removed by gastroscopy and one small bowel ileal obstruction, which was removed by ileoscopy. The final satisfaction degree was good in 60% of cases. CONCLUSIONS: EIGB placement by x-ray seems feasible and safe. Although some devices have a shorter duration than expected, such as < 16 weeks in 29% patients and < 12 weeks in 8.3% of patients, an acceptable weight loss at four months was obtained. There were some adverse effects that required endoscopy, thus we advise that the procedure be supervised by a bariatric endoscopist.

Bariatric and metabolic endoscopy in the handling of fatty liver disease. A new emerging approach?

BACKGROUND: non-alcoholic fatty liver disease (NAFLD) is the most frequent cause of chronic hepatopathy in our environment. However, the benefits of the bariatric endoscopy in this disease are barely documented. OBJECTIVES: to evaluate changes in NAFLD, via non-invasive methods in obese patients who underwent bariatric restrictive endoscopy. Weight, metabolic changes and the level of technical safety were also analyzed as secondary objectives. METHODS: thirty patients with NAFLD and obesity (mean BMI 38.22 ± 6.55 kg/m2) underwent bariatric restrictive endoscopy; this included 15 one-year intragastric balloons and 15 sutured gastroplasties (ESG-Apollo®). A non-invasive prospective analysis was performed via analytical (hepatic function, insulin-resistance and hepatic steatosis/fibrosis scores) and ultrasonographic parameters. In addition, anthropometric features and the evolution of the main obesity-related comorbidities were evaluated. The follow-up period was one year in all cases. RESULTS: thirty patients were included; 63% were female with a mean age of 46 ± 13.8 years. There was a decrease in FLI, HSI, NAFLD-Fibrosis Score, hepatic ultrasonographic steatosis, subcutaneous fat (p < 0.001), HOMA-IR, insulin and triglycerides (p < 0.05) after 12 months. An average EWL of 44.02% (16.34% TBWL) was obtained after one year, with EWL > 25% in 27/30 patients (TBWL > 10% in 25/30 patients) (p < 0.001). Obesity-related comorbidities were resolved in 17/30 (57%) of cases, 5/8 (62.5%) HTA, 5/12 (41.7%) DLP, 2/4 (50%) T2DM, 2/3 (66.7%) SOAS and 3/3 (100%) arthropathy. An improvement in HbA1c in the ESG-Apollo group (p = 0.017) was the only difference. One migrated and spontaneously expelled balloon was the only technical incidence. CONCLUSIONS: bariatric endoscopy could be proposed during short-term follow-up as an effective and safe alternative in patients with obesity and NAFLD. It stimulates weight loss and improves analytical and ultrasound parameters from hepatic fat, insulin-resistance and hypertriglyceridemia. It also improves associated major comorbidities.

Improving the Security and QoE in Mobile Devices through an Intelligent and Adaptive Continuous Authentication System.

Continuous authentication systems for mobile devices focus on identifying users according to their behaviour patterns when they interact with mobile devices. Among the benefits provided by these systems, we highlight the enhancement of the system security, having permanently authenticated the users; and the improvement of the users' quality of experience, minimising the use of authentication credentials. Despite the benefits of these systems, they also have open challenges such as the authentication accuracy and the adaptability to new users' behaviours. Continuous authentication systems should manage these challenges without forgetting critical aspects of mobile devices such as battery consumption, computational limitations and response time. With the goal of improving these previous challenges, the main contribution of this paper is the design and implementation of an intelligent and adaptive continuous authentication system for mobile devices. The proposed system enables the real-time users' authentication by considering statistical information from applications, sensors and Machine Learning techniques based on anomaly detection. Several experiments demonstrated the accuracy, adaptability, and resources consumption of our solution. Finally, its utility is validated through the design and implementation of an online bank application as proof of concept, which allows users to perform different actions according to their authentication level.

Efficacy and safety of transoral outlet reduction via endoscopic suturing in patients with weight regain after a surgical Roux-en-Y gastric bypass.

INTRODUCTION: many patients that undergo bariatric surgery (Roux-en-Y gastric bypass [RYGB]) may regain some of their weight lost over time. A transoral outlet reduction (TORe) with endoscopic suture could be a valid alternative in these patients. METHODS: this was a retrospective initial series of 13 consecutive patients with weight regain after RYGB and a dilated gastro-jejunal anastomosis (> 15 mm). TORe was performed using an endoscopic transmural suture device (OverStitch-Apollo®), which was used to reduce the anastomosis aperture and also to treat the gastric pouch. The initial data of feasibility, safety and weight loss are described with a limited follow-up of six months. RESULTS: there was a mean maximum weight loss of 37.69 kg after RYGB and a subsequent average regain of 21.62 kg. The mean anastomosis diameter was 36 mm (range 20-45) which was reduced to 9 mm (range 5-12) (75% reduction), with an average of 2.5 sutures. The mean pouch size was 7.2 cm (range 2-10), which decreased to 4.7 cm (range 4-5) (34.72% reduction), with an average of 2.7 sutures. The mean weight loss six months after TORe was 12.29 kg, a weight loss of 56.85% of the weight regained after RYGB. No complications related to the procedure were recorded. CONCLUSIONS: endoscopic suture reduction of the dilated gastro-jejunal anastomosis and the gastric pouch seems a feasible and safe option in our limited initial experience. With a multidisciplinary approach and a short term follow-up, this seems to be a minimally invasive and effective option to control weight regain after RYGB.

Pilot-scale biopesticide production by Bacillus thuringiensis subsp. kurstaki using starch industry wastewater as raw material.

Pilot-scale Bacillus thuringiensis based biopesticide production (2000 L bioreactor) was conducted using starch industry wastewater (SIW) as a raw material using optimized operational parameters obtained in 15 L and 150 L fermenters. In pilot scale fermentation process the oxygen transfer rate is a major limiting factor for high product yield. Thus, the volumetric mass transfer coefficient (KLa) remains a tool to determine the oxygen transfer capacity [oxygen utilization rate (OUR) and oxygen transfer rate (OTR)] to obtain better bacterial growth rate and entomotoxicity in new bioreactor process optimization and scale-up. This study results demonstrated that the oxygen transfer rate in 2000 L bioreactor was better than 15 L and 150 L fermenters. The better oxygen transfer in 2000 L bioreactor augmented the bacterial growth [total cell (TC) and viable spore count (SC)] and delta-endotoxin yield. Prepared a stable biopesticide formulation for field use and its entomotoxicity was also evaluated. This study result corroborates the feasibility of industrial scale operation of biopesticide production using starch industry wastewater as raw material.

Influence of the hole geometry on the flow distribution in ventricular catheters for hydrocephalus.

BACKGROUND: Hydrocephalus is a medical condition consisting of an abnormal accumulation of cerebrospinal fluid within the brain. A catheter is inserted in one of the brain ventricles and then connected to an external valve to drain the excess of cerebrospinal fluid. The main drawback of this technique is that, over time, the ventricular catheter ends up getting blocked by the cells and macromolecules present in the cerebrospinal fluid. A crucial factor influencing this obstruction is a non-uniform flow pattern through the catheter, since it facilitates adhesion of suspended particles to the walls. In this paper we focus on the effects that tilted holes as well as conical holes have on the flow distribution and shear stress. METHODS: We have carried out 3D computational simulations to study the effect of the hole geometry on the cerebrospinal fluid flow through ventricular catheters. All the simulations were done with the OpenFOAM® toolbox. In particular, three different groups of models were investigated by varying (i) the tilt angles of the holes, (ii) the inner and outer diameters of the holes, and (iii) the distances between the so-called hole segments. RESULTS: The replacement of cylindrical holes by conical holes was found to have a strong influence on the flow distribution and to lower slightly the shear stress. Tilted holes did not involve flow distribution changes when the hole segments are sufficiently separated, but the mean shear stress was certainly reduced. CONCLUSIONS: The authors present new results about the behavior of the fluid flow through ventricular catheters. These results complete earlier work on this topic by adding the influence of the hole geometry. The overall objective pursued by this research is to provide guidelines to improve existing commercially available ventricular catheters.

Parametric study of ventricular catheters for hydrocephalus.

BACKGROUND: To drain the excess of cerebrospinal fluid in a hydrocephalus patient, a catheter is inserted into one of the brain ventricles and then connected to a valve. This so-called ventricular catheter is a standard-size, flexible tubing with a number of holes placed symmetrically around several transversal sections or "drainage segments". Three-dimensional computational dynamics shows that most of the fluid volume flows through the drainage segment closest to the valve. This fact raises the likelihood that those holes and then the lumen get clogged by the cells and macromolecules present in the cerebrospinal fluid, provoking malfunction of the whole system. In order to better understand the flow pattern, we have carried out a parametric study via numerical models of ventricular catheters. METHODS: The parameters chosen are the number of drainage segments, the distances between them, the number and diameter of the holes on each segment, as well as their relative angular position. RESULTS: These parameters were found to have a direct consequence on the flow distribution and shear stress of the catheter. As a consequence, we formulate general principles for ventricular catheter design. CONCLUSIONS: These principles can help develop new catheters with homogeneous flow patterns, thus possibly extending their lifetime.

Energy balance of biofuel production from biological conversion of crude glycerol.

Crude glycerol, a by-product of biodiesel production, has gained significant attention as a carbon source for biofuel production. This study evaluated the energy balance of biodiesel, hydrogen, biogas, and ethanol production from 3.48 million L of crude glycerol (80% w/v). The conversion efficiency (energy output divided by energy invested) was 1.16, 0.22, 0.27, and 0.40 for the production of biodiesel, hydrogen, biogas, and ethanol respectively. It was found that the use of crude glycerol for biodiesel production was an energy gain process, with a positive energy balance and conversion efficiency of greater than 1. The energy balance revealed a net energy gain of 5226 GJ per 1 million kg biodiesel produced. Production of hydrogen, biogas and ethanol from crude glycerol were energy loss processes. Therefore, the conversion of crude glycerol to lipids and subsequently to biodiesel is suggested to be a better option compared to hydrogen, biogas, or ethanol production with respect to energy balance.

New designs of ventricular catheters for hydrocephalus by 3-D computational fluid dynamics.

INTRODUCTION: Based on a landmark study by Lin et al. of the two-dimensional flow in ventricular catheters (VCs) via computational fluid dynamics (CFD), we studied in a previous paper the three-dimensional flow patterns of five commercially available VC. We found that the drainage of the cerebrospinal fluid (CSF) mostly occurs through the catheter's most proximal holes. In this paper, we design five VC prototypes with equalized flow characteristics. METHODS: We study five prototypes of VC by means of CFD in three-dimensional (3-D) automated models and compare the fluid-mechanical results with our previous study of currently in use VC. The general procedure for the development of a CFD model calls for transforming the physical dimensions of the system to be studied into a virtual wire-frame model, which provides the coordinates for the virtual space of a CFD mesh. The incompressible Navier-Stokes equations, a system of strongly coupled, nonlinear, partial differential equations governing the motion of the flow field, are then solved numerically. RESULTS: By varying the number of drainage holes and the ratio hole/segment, we improved flow characteristics in five prototypes of VC. Models 1, 2, and 3 have a distal to proximal decreasing flow. Model 4 has an inverse flow to the previous ones, that is, a distal to proximal increasing flow, while model 5 has a constant flow over the segments. CONCLUSIONS: New catheter designs with variable hole diameter, number of holes, and ratio hole/segment along the catheter allow the fluid to enter the catheter more uniformly along its length, thus reducing the chance that the catheter becomes occluded.

Basic cerebrospinal fluid flow patterns in ventricular catheters prototypes.

OBJECT: A previous study by computational fluid dynamics (CFD) of the three-dimensional (3-D) flow in ventricular catheters (VC) disclosed that most of the total fluid mass flows through the catheter's most proximal holes in commercially available VC. The aim of the present study is to investigate basic flow patterns in VC prototypes. METHODS: The general procedure for the development of a CFD model calls for transforming the physical dimensions of the system to be studied into a virtual wire-frame model which provides the coordinates for the virtual space of a CFD mesh, in this case, a VC. The incompressible Navier-Stokes equations, a system of strongly coupled, nonlinear, partial differential conservation equations governing the motion of the flow field, are then solved numerically. New designs of VC, e.g., with novel hole configurations, can then be readily modeled, and the corresponding flow pattern computed in an automated way. Specially modified VCs were used for benchmark experimental testing. RESULTS: Three distinct types of flow pattern in prototype models of VC were obtained by varying specific parameters of the catheter design, like the number of holes in the drainage segments and the distance between them. Specifically, we show how to equalize and reverse the flow pattern through the different VC drainage segments by choosing appropriate parameters. CONCLUSIONS: The flow pattern in prototype catheters is determined by the number of holes, the hole diameter, the ratio hole/segment, and the distance between hole segments. The application of basic design principles of VC may help to develop new catheters with better flow circulation, thus reducing the possibility of becoming occluded.

[Cellular effectors of the inflammatory response in chronic obstructive pulmonary disease (COPD)]. / Efectores celulares de la respuesta inflamatoria en la enfermedad pulmonar obstructiva crónica.

Approximately 3 million people in the world die every year as a consequence of COPD, which is associated with an abnormal inflammatory response of the lung to noxious particles and gases. This inflammatory pattern causes pathological changes leading to a narrowing of small airways and destruction of lung parenchyma, also known as emphysema. Classically, these changes were associated to macrophages and neutrophils, although T CD8+ lymphocytes were latter added to the equation to explain the origin of emphysematous lesions. However, in recent years, multiple evidences have arisen indicating that inflammatory response in COPD is much more complex. These findings point to a key role for mast cells, dendritic cells, T CD4+ and B cells. The aim of this article is to review such evidence and report what is known so far about those cells involved in the inflammatory response in COPD.

Multiple interdigital neuromas: a retrospective study of 279 feet with 462 neuromas.

Morton's neuroma is a common pathologic entity that, traditionally, was considered to be an isolated tumor that rarely affected more than 1 interdigital space. However, in recent years, multiple neuromas have become more common in our day-to-day practice. The objective of the present study was to assess the frequency with which Morton's neuroma appears in the different interdigital spaces. A retrospective study was performed of 279 feet that had been surgically treated for Morton's neuroma using a dorsal approach during a 9-year period (from January 2003 to December 2011), with an ultrasound scan taken preoperatively and histopathologic analysis performed afterward. From the 279 treated feet, 462 interdigital neuromas were surgically removed. Of the 279 feet, 97 (34.8%) displayed isolated neuromas, and 182 (65.2%) were treated for multiple neuromas. Regarding the neuromas that were treated as isolated lesions, 74.2% were located in the third space. For the feet affected by multiple interdigital neuromas, 100% had a neuroma in the third space and 98.9% in the second. The incidence of multiple interdigital neuromas can be considered frequent. The assessment, therefore, of interdigital neuromas of the foot should include, at a minimum, the second and third interdigital spaces.

Ecto-nucleotidases activities in the contents of ovarian endometriomas: potential biomarkers of endometriosis.

Endometriosis, defined as the growth of endometrial tissue outside the uterus, is a common gynecologic condition affecting millions of women worldwide. It is an inflammatory, estrogen-dependent complex disorder, with broad symptomatic variability, pelvic pain, and infertility being the main characteristics. Ovarian endometriomas are frequently developed in women with endometriosis. Late diagnosis is one of the main problems of endometriosis; thus, it is important to identify biomarkers for early diagnosis. The aim of the present work is to evaluate the ecto-nucleotidases activities in the contents of endometriomas. These enzymes, through the regulation of extracellular ATP and adenosine levels, are key enzymes in inflammatory processes, and their expression has been previously characterized in human endometrium. To achieve our objective, the echo-guided aspirated fluids of endometriomas were analyzed by evaluating the ecto-nucleotidases activities and compared with simple cysts. Our results show that enzyme activities are quantifiable in the ovarian cysts aspirates and that endometriomas show significantly higher ecto-nucleotidases activities than simple cysts (5.5-fold increase for ATPase and 20-fold for ADPase), thus being possible candidates for new endometriosis biomarkers. Moreover, we demonstrate the presence of ecto-nucleotidases bearing exosomes in these fluids. These results add up to the knowledge of the physiopathologic mechanisms underlying endometriosis and, open up a promising new field of study.

Computational fluid dynamics of ventricular catheters used for the treatment of hydrocephalus: a 3D analysis.

INTRODUCTION: The most common treatment for hydrocephalus remains the ventriculoperitoneal shunt. Yet, the most frequent complication is ventricular catheter obstruction, which may account for 50-80 % of newly inserted shunts. Although many factors contribute to this, the main one is related to flow characteristics of the catheter within the hydrocephalic brain. A landmark study by Lin et al. addressed the problem of fluid characteristics in ventricular catheters using a two-dimensional simulation program of computational fluid dynamics (CFD). METHODS: The authors have studied five current commercially available ventricular catheter designs using CFD in three-dimensional automated designs. The general procedure for the development of a CFD model involves incorporating the physical dimensions of the system to be studied into a virtual wire-frame model. The shape and features of the actual physical model are transformed into coordinates for the virtual space of the computer and a CFD computational grid (mesh) is generated. The fluid properties and motion are calculated at each of these grid points. After grid generation, flow field boundary conditions are applied, and the fluid's thermodynamic and transport properties are included. At the end, a system of strongly coupled, nonlinear, partial differential conservation equations governing the motion of the flow field are numerically solved. This numerical solution describes the fluid motion and properties. RESULTS: The authors calculated that most of the total fluid mass flows into the catheter's most proximal holes. Fifty to 75 % flows into the two most proximal sets of inlets of current commercially available 12-32-hole catheters. Some flow uniformity was disclosed in Rivulet-type catheter. CONCLUSIONS: Most commercially available ventricular catheters have an abnormally increase flow distribution pattern. New catheter designs with variable hole diameters along the catheter tip will allow the fluid to enter the catheter more uniformly along its length, thereby reducing the probability of its becoming occluded.

Biphalangeal/triphalangeal fifth toe and impact in the pathology of the fifth ray.

BACKGROUND: Having reviewed the studies on the biphalangeal fifth toe, we have observed a great disparity of data depending on the research center. We have investigated the frequency of biphalangeal toes and also its handedness. We have also analyzed the relationship of pathological deviations of fifth toe with this feature and with the fifth metatarsal. METHODS: We performed a descriptive prospective study, which analyzed 2494 feet (1247 people) with bilateral dorsoplantar radiographs. We studied the number of phalanges of the fifth toe, the deviations in the sagittal and transverse plane, and the state of the fifth metatarsal phalangeal joint. RESULTS: After analyzing the data we found the presence of biphalangeal fifth toe in 46.3% of the feet, presenting this feature bilaterally in 97.4% of them. A statistically significant higher percentage of pathological toes was found in people with triphalangeal fifth toe (pathological in 29.91%) than in the biphalangeal toes (pathological in 15.60%). We found that these differences are accentuated in the alterations of the fifth toe in the sagittal plane. CONCLUSIONS: It is almost 4 times more likely to suffer a fifth hammer toe if the fifth toe is triphalangeal (OR = 3.98 to p = 0.000). Alterations in the coronal plane of the fifth toe are associated with tailor's bunion (p = 0.000). We did not find any significant differences regarding the need for surgery of the fifth toe of the biphalangeal (39.1%) versus triphalangeal toes (60.9%). CLINICAL RELEVANCE: There may be an association between pathologic deviations and bigger mobility of the triphalangeal fifth toes. However, biphalangeal fifth toes show bigger rigidity leading to smaller accommodation inside the shoe, which may lead to less painful feet and decreased proportion of surgery.