Two-dimensional cellular automaton model for mixed-culture biofilm

Structural and microbial heterogeneity occurs in almost any type of biofilm system. General approaches for the design of biofilm systems consider biofilms as homogeneous and of constant thickness. In order to improve the design of biofilms systems, models need to incorporate structural heterogeneity and the effect of inert microbial mass. We have improved a 2D biofilm model based on cellular automata (CA) and used it to simulate multidimensional biofilms with active and inert biomass including a self-organizing development. Results indicate that the presence of inert biomass within biofilm structures does not change considerably the substrate flux into the biofilm because the active biomass is located at the surface of the biofilm. Long-term simulations revealed that although the biofilm system is highly heterogeneous and the microstructure is continuously changing, the biofilm reaches a dynamic steady-state with prediction of biofilm thickness and substrate flux stabilizing on a delimited range.

Genotipo y expresión fenotípica de la hemocromatosis hereditaria en España

INTRODUCTION

The prevalence of C282Y homozygosity in patients with hereditary hemochromatosis (HH) has been reported to be markedly lower in the Mediterranean Basin than in northern Europe. In Spain, the available data are contradictory and limited to small series in specific regions. The objective of this study is to determine the prevalence of the 2 main HFE gene mutations in a large series of unrelated Spanish patients with HH from different geographical origins.

PATIENTS AND METHOD

The criteria for HH diagnosis were: repeat serum transferrin saturation index (> 45% plus C282Y homozygosity and/or hepatic iron index (> 1.9 of dry liver weight in non-cirrhotic patients or (> 4.1 in patients with liver cirrhosis. Cases in related individuals were excluded. Demographic data, clinical expression, iron parameters and HFE gene mutations (C282Y and H63D) were assessed in 222 patients.

RESULTS

A total of 83.3% of patients were C282Y homozygous and 5% were compound heterozygous (C282Y/H63D). No significant differences in phenotypic expression or in the frequency of C282Y homozygosity were observed between patients born in the North and South of Spain.

CONCLUSION

The genotypic and phenotypic expression of HH in Spain is very similar to that reported in Northern Europe. Thus, the genetic heterogeneity described in some Southern European regions cannot be considered a common feature to all countries of the Mediterranean Basin.

Isovolumic Contraction Time by Pulsed-Wave Doppler Tissue Imaging in Aortic Stenosis

BACKGROUND

Doppler Tissue Imaging (DTI) has been evaluated in ischaemic heart disease and some cardiomyopathies. In patients with aortic stenosis (AS), left ventricular contraction is slowered. This study aimed to evaluate the possible role of the measurement of isovolumic contraction time (ICT) by DTI in the evaluation of AS severity.

METHODS

The study population constitutes 30 patients: 15 with AS (nine severe and six non-severe) and 15 control subjects. All of them had normal systolic function, sinus rhythm, and absence of ischaemic heart disease of conduction abnormalities. ICT was defined as the time from the onset of the QRS complex to the beginning of the DTI systolic wave. The correlation between ICT and aortic area obtained by continuity equation, as well as the diagnostic value of ICT in the identification of severe AS were studied.

RESULTS

ICT was significantly increased in patients with severe AS (98+/-27 versus 65+/-21 ms, p=0.024). There was a significant correlation between ICT and aortic area (r=-0.56; p=0.035). The receiver operator characteristic curve of ICT in the identification of severe AS yielded an area under the curve of 0.852 (95% confidence interval: 0.665-1.0). The two best cut-points were >73 ms (88% sensitivity, 77% specificity) and >85 ms (78% sensitivity, 83% specificity). A value of >41 ms had a 100% sensitivity, but only a 17% specificity, and >91 ms showed a 100% specificity, but only a 44% sensitivity.

CONCLUSIONS

ICT measured by pulsed-wave DTI is increased in patients with aortic stenosis.

[Serotypes and antibiotic susceptibility of Streptococcus pneumoniae in children in the health district of Valencia and Castellón, Spain: a multicenter, prospective trial]

A study was conducted to determine the serotypes, the coverage of the heptavalent conjugate vaccine (VCN 7-v) and the antibiotic susceptibility of Streptococcus pneumoniae in children (<15 years) in the health districts of the provinces of Castellon and Valencia, Spain, from June 1999 to December 2002. A total of 271 strains were evaluated, 15.5% of which were invasive, 63.5% were of respiratory origin and 22.5% were from conjunctival and otitic exudates; 67.2% of the strains were found in children younger than 2 years of age. The distribution of the serotypes showed slight changes according to age and the origin of the sample: the most common serotypes were 19, 6, 23, 14, 3, 9 and 11; however, in children younger than 2 years of age the order changed to 19, 6, 14 and 23, 9, 11 and 3, and in the invasive strains to 19, 6, 14, 3 and 23. A total of 27.2% of the stains were susceptible to the ten antibiotics tested. For penicillin, reduced susceptibility was found in 50.4% and high resistance in 5.8%; 98.3% were susceptible to ampicillin and amoxicillin-clavulanic acid, and 80.7% to cefuroxime; 52.5% were resistant to erythromycin and 43.7% to clindamycin. No strains were resistant to rifampicin, vancomycin, levofloxacin or cefotaxime. The most susceptible serotypes were 3 and 11, and the most resistant was 14 (which consistently showed resistance to an antibiotic), 19, 6 and 23. According to these data, the theoretical coverage of VCN 7-v would be 80.1% in children younger than 2 years and 73.43% in those aged 0-14 years.

[Thomas' shunt for hemodialysis: dysfunction and its percutaneous treatment]

PURPOSE

To assess the usefulness of percutaneous treatment of abnormalities of the venous tree in extending the survival of external Thomas shunts (TS).

MATERIALS AND METHODS

Twelve cases of TS were included in a hemodialysis access fistula dysfunction monitoring program and were followed for up to 48 months. The abnormalities found were treated by percutaneous transluminal angioplasty (PTA) or thrombolysis and PTA. Survival curves and the Kaplan-Meier method were used to calculate the likelihood of primary patency (P1), secondary patency (P2), and overall patency (OP).

RESULTS

A total of 61 interventions were performed during the period of follow-up. On 12 occasions the fistula was thrombosed; in the rest, increased venous pressure to 150 mmHg or higher was detected during dialysis. Fistulography was performed after washing the thrombosed fistulas with urokinase, and revealed one or more of the following angiographic signs: 1) a short reduction of more than 50% in lumen caliber in the femoral vein adjacent to the anastomosis, present in 52% of the cases (fig. 1); 2) imaging a "jet" of contrast material at the site of entry of the shunt into the femoral vein (fig. 2), present in 22% of the cases; and 3) a filling defect or "flap" at the same site, owing to hyperplastic tissue or piece of thrombus adhering to the intima, present in 34% of the cases (figs. 3-5). This last-mentioned finding ordinarily gave rise to a "valve" effect, whereby injection into the venous branch was feasible but aspiration from the venous branch was difficult or impossible. PTA was carried out and attained anatomical and functional success in 100% of cases. PI was 58%, 33%, 8%, and 0% at 6, 12, 24, and 36 months, respectively; P2 was 100%, 75%, 58%, and 25%; respectively, at those same times. The comparison of the PI and P2 curves was statistically significant; p < 0.001 (table 1). OP was 83%, 66%, 50% and 41% at 12, 24, 36 and 48 months. The comparison of the PI surgical and OP curves was statistically significant; p < 0.01 (table II).

CONCLUSIONS

Percutaneous treatment of TS dysfunction was proved to be effective in maintaining long-term patency. This type of fistula affords an alternative to tunneled central venous catheters.

Long term outcome of patients with postinfarction left ventricular pseudoaneurysm

BACKGROUND

It is debatable whether surgical repair is routinely indicated in asymptomatic patients with left ventricular pseudoaneurysms.

OBJECTIVE

To evaluate the long term outcome of patients with pseudoaneurysm after myocardial infarction, focusing on those treated conservatively.

METHODS

10 patients with postinfarction left ventricular pseudoaneurysm were followed up over a mean (SD) period of 3.8 (5.2) years.

RESULTS

In those treated conservatively (n = 9), cumulative survival was 88.9 (10.5)% and 74.1 (16.1)% at one and four years, respectively. The probability of being free of cardiac death was 88.9 (10.5)% at both one and four years. No patient had complete fatal heart rupture during follow up. Three patients suffered ischaemic stroke (at 1, 11, and 62 months). The cumulative incidence of ischaemic stroke was 10% at one year and 32.5% at four years.

CONCLUSIONS

Long term outcome of patients with postinfarction left ventricular pseudoaneurysm is relatively benign, with a very low risk (none in this series) of fatal rupture. Taking into consideration the relatively high risk of stroke, chronic anticoagulant treatment could be considered.

Genetic marker variation in coastal populations of Chile

Gene frequencies for nine genetic marker systems are presented for the following Chilean coastal populations: Paposo, Carelmapu, Laitec and Ukika. Historical and anthropological data suggest the presence of descendants of the Amerindian populations, specifically of Changos, Cuncos, Chonos and Yamanas in these populations. Results indicate that the studied groups maintain an important aboriginal genetic composition. According to Amerindian admixture estimates, the genetic isolation of coastal populations is lower than that of inland populations, suggesting that proximity to the sea facilitated gene flow. Genetic distances and dendrograms were obtained for these populations and another four Chilean Indian populations. Results agree with expectations, taking geographic isolation and non-aboriginal admixture into account.

[Clinical predictors of the presence of perfusion defects in more than than one territory in myocardial scintigraphy with GATED-SPECT]

BACKGROUND AND OBJECTIVE

Extension of perfusion defects is associated with outcome in patients undergoing myocardial scintigraphy. The study aimed to identify the clinical characteristics that can predict the existence of perfusion defects in more than one territory in patients referred for myocardial scintigraphy with GATED-SPECT.

PATIENTS AND METHODS

A total of 193 patients undergoing myocardial scintigraphy with GATED-SPECT (99mTc-tetrofosmine) were studied. Clinical variables and scintigraphy results were studied to determine what clinical variables are associated with perfusion defects in more than one territory.

RESULTS

The number of territories with perfusion defects per patient was 1.1 0.8 and 29% had perfusion defects in > 1 territory. Patients with greater probability of having perfusion defects in > 1 territory were those with previous myocardial infarction (44% vs 21%, p = 0.030) and males (33% vs 10%, p = 0.006). In addition, patients with > 2 coronary risk factors had a statistical tendency to have defects in > 1 territory (47% vs 20%, p = 0.057). Only 15% of the patients with one of these three characteristics had perfusion defects in > 1 territory in comparison with 45% and 83% in those with 2 or 3 factors, respectively.

CONCLUSION

Considering 3 simple clinical characteristics (male gender, previous infarction and existence of > 2 coronary risk factors), it is possible to predict which patients are more likely to show perfusion defects in > 1 territory during GATED-SPECT myocardial scintigraphy.

[Diagnostic value of gated-SPECT for each coronary artery in patients clinically diagnosed of coronary heart disease]

This study aimed to evaluate the diagnostic value of gated-SPECT for each coronary artery in patients with clinical diagnosis or suspicion of coronary heart disease.

PATIENTS AND METHODS

The study population is made up of 43 patients (64 9 years, 88% male gender) with prior clinical diagnosis or suspicion of coronary heart disease who had undergone gated-SPECT (99mTc-tetrofosmin) and cardiac catheterization. Scintigraphic study after exercise treadmill test and rest study were performed on the same day.

RESULTS

Gated-SPECT showed perfusion defects in 86% of patients, the mean number of territories with perfusion defects being 1.58 +/- 0.79. A total of 39 (91%) of the 43 patients had significant coronary heart disease. Single, two- and three-vessel disease was demonstrated in 12 (28%), 15 (35%) and 12 (28%) patients, respectively. Sensitivity and specificity were 81% and 91%, respectively, for left anterior descending artery, 88% and 65% for right coronary artery, and 55% and 81% for circumflex one.

CONCLUSIONS

Myocardial scintigraphy with gated-SPECT offers high sensitivity and specificity for the diagnosis of left anterior descending artery disease. However, sensitivity for circumflex artery and specificity for right coronary artery were low in our series.

Reason for discrepancies in identifying myocardial viability by thallium-201 redistribution, magnetic resonance imaging, and dobutamine echocardiography

Dobutamine echocardiography (DE), magnetic resonance imaging (MRI), and thallium redistribution (TS) are used to assess cardiac viability. However, these modalities sometimes yield contradictory results. Our aim was to establish the degrees of agreement among DE, MRI, and TS in identifying myocardial viability and to analyze the minimum critical mass of live (viable) cells required for each test to identify viability. A prospective study was done in which DE, MRI, and TS were consecutively performed in 10 ischemic patients scheduled for heart transplantation. The explanted heart was analyzed to quantify the amount of live cells per segment. The pathologic data were compared with the test results to analyze the minimum mass of viable cells required by each technique to identify viability. Mean age was 58 +/- 8 years (8 men). The mean ejection fraction was 0.27 +/- 0.04. Seven patients had severe cardiac failure (New York Heart Association functional class IV) and 6 patients had refractory angina. A total of 150 cardiac segments were analyzed. Among the 150 segments, 107 (71.3%) showed some degree of myocardial necrosis. Mean total area, mean fatty area, and mean necrotic area per segment were 2.53 +/- 0.7, 0.13 +/- 0.2, and 0.55+/-0.5 cm(2), respectively. As expected, a higher amount of necrotic tissue was found in nonviable segments. From the 150 segments, DE identified 90 as viable and 60 as nonviable. These data were similar to that of MRI (98 viable and 52 nonviable). A higher proportion of viable segments was found by TS (117 viable vs 33 nonviable). The concordance between DE and TS was only moderate (kappa 0.49). The agreement between MRI and TS also showed moderate concordance (kappa 0.56). The highest agreement was found between DE and MRI (kappa 0.73). Thus, discrepancies in assessing viability by DE, MRI, and TS may be due to differences in the minimum critical mass of live myocytes required by each technique to diagnose viability. Thallium requires a lesser amount of live tissue than DE or MRI to detect viability; also, its maximum diagnostic efficiency is obtained with lesser amounts of live tissue on each segment. These considerations should be taken into account when these diagnostic tests are used for the detection of viability before revascularization procedures.

Congenital quadricuspid aortic valve associated with congenital complete heart block

Congenital quadricuspid aortic valve is very uncommon, and is often associated with other cardiac disorders, such as patent ductus, ventricular septal defect, pulmonary stenosis, mitral valve malformation, hypertrophic cardiomyopathy and coronary abnormalities. We report a patient with congenital quadricuspid aortic valve associated with congenital complete heart block. To our knowledge, this association has not been reported so far.

[Hookwire localization of pulmonary nodules for video-thorascopic surgical resection]

OBJECTIVES

To assess the usefulness of a technique for inserting hookwires guided by computed tomography to locate and resect pulmonary nodules by video-assisted thoracoscopy. To describe the procedure and its complications.

PATIENTS AND METHODS

Nine pulmonary nodules were located in nine patients. All were </= 2 cm in diameter, radiologically undefined and of unknown origin. Four patients had a history of cancer. The nodules were located using the needle/hookwire system (Kopans), guided by computed tomography and were resected by video-assisted thoracic surgery.

RESULTS

The hookwire was placed correctly in 8 patients and incorrectly in 1. Thoracotomy was necessary for 1 patient. The histologic diagnosis was benign for all 9 nodules; 5 were hamartomas, 2 were necrotic or fibrotic nodules, 1 was a granuloma and 1 was an anthracotic node. Hospital stay ranged from 1 to 8 days (mean 3.3 days).

CONCLUSION

The location of pulmonary nodes by hookwire and needle for later resection by video-assisted thoracoscopic surgery is a simple, safe way to facilitate removal in some cases, for diagnosis and treatment.

Weak concordance between wall motion and microvasculature status after acute myocardial infarction: study with myocardial contrast echocardiography in real time with power modulation

AIMS

The microvasculature damage after myocardial infarction has important implications. The hypothesis of the study was that wall motion abnormalities and microcirculation status do not necessarily match after myocardial infarction, and therefore the study of only myocardial wall motion could offer an incomplete evaluation in these patients.

METHODS

Wall motion and myocardial perfusion assessed by contrast echocardiography were evaluated by two different blinded investigators in 29 patients with recent (<1 week) myocardial infarction. Myocardial perfusion was assessed in real-time using power modulation after Optison (1.5-3.0 ml) intravenous administration.

RESULTS

One hundred and ninety-nine segments could be adequately evaluated. Of these, 54 (27%) were akinetic. Regarding contrast opacification, 134 segments (67%) had a normal perfusion, whereas the remaining 65 (33%) had an impaired (n=37, 19%) or absent (n= 28, 14.1%) perfusion. Concordance between presence of akinesia and abnormal contrast opacification was only moderate (kappa index 0.42) and agreement only occurred in 116 segments (58%). Fourteen per cent of normoquinetic segments had an impaired perfusion, whereas 35% of akinetic segments had a preserved perfusion. Correlation between the proportion of segments with akinesia and the proportion of segments with impaired perfusion was moderate (r=0.41), and there was no correlation between the proportion of segments with akinesia and the percentage of segments with absent perfusion.

CONCLUSION

There is a weak association between regional systolic function and myocardial perfusion after myocardial infarction, as assessed by real-time contrast myocardial echocardiography using power modulation.

Usefulness of contrast agents in the diagnosis of left ventricular pseudoaneurysm after acute myocardial infarction

BACKGROUND AND OBJECTIVE

The diagnosis of left ventricular pseudoaneurysm after acute myocardial infarction is usually based on echocardiography. However, this technique may have limitations in some patients, especially in cases with suboptimal acoustic window. The objective of this study was to evaluate the usefulness of contrast echocardiography in the diagnosis of left ventricular pseudoaneurysm after myocardial infarction.

METHODS AND RESULTS

The study population comprises six patients in whom a two-dimensional echocardiography showed an image consistent with left ventricular pseudoaneurysm. Levovist (Schering) 4gr was administered i.v. to more clearly visualize the blood flow from the left ventricle to the left ventricular pseudoaneurysm cavity in all patients. Infarct location was anterior in five patients, and posterolateral in one. No patient had received thrombolysis or primary angioplasty during the acute phase. The transthoracic echocardiographic study showed an echo-free space adjacent to left ventricle in all patients. In four cases, the diagnosis of left ventricular pseudoaneurysm was made before contrast administration. In the remaining two patients, the definite diagnosis was made only after Levovist administration.

CONCLUSION

In the diagnosis of postinfarction left ventricular pseudoaneurysm, the administration of contrast agents may be of help in the correct visualization of the blood flow from the left ventricle to the left ventricular pseudoaneurysm cavity, and may allow a definite diagnosis to be obtained in some patients.

New issues in severity scoring: interfacing the ICU and evaluating it

Since the development of the first general outcome prediction models, these instruments have been widely used in the intensive care unit (ICU), both for patient evaluation and for ICU evaluation. Since some of these uses have been serious questioned, we assisted in the last years to the exploration of alternative paths for increasing the predictive power of the models and to enhance their applicability and utility in the real world. Part of these efforts focused on the exploration of more meaningful outcomes (clinical and non-clinical) with a strong tonic into the relation between outcomes and resources use. Also, since it is now widely recognized that the ICU is not an island, but it is integrated in a continuum of care, more and more efforts are being made to optimize and evaluate the interface between the ICU and the hospital, both at ICU admission and at ICU discharge. The objective of this review is to present and discuss, to the clinician working in the ICU, these emerging issues.