Validation of the Kidney Failure Risk Equation in the Colombian Population.

Introduction: Chronic kidney disease prevention programs must identify patients at risk of early progression to provide better treatment and prolong kidney replacement therapy-free survival. Risk equations have been developed and validated in cohorts outside of Colombia, so this study aims to evaluate the discrimination and calibration of the four-variable kidney failure risk equation in a Colombian population where it has yet to be validated. Methods: External validation study of a kidney failure risk equation using a historical cohort of patients with CKD stages 3, 4, and 5, adults without a history of dialysis or kidney transplantation with a two-year follow-up, belonging to the Baxter Renal Care Services Colombia network. The discriminatory capacity of the model was evaluated by the concordance index using Harrell's C statistic, and the time-dependent area under the receiver operating characteristic (ROC) curve was estimated using the nearest neighbor method, as well as the optimal cut-off point for sensitivity and specificity. Calibration was determined by the degree of agreement between the observed outcome and the probabilities predicted by the model using the Hosmer-Lemeshow statistic. Results: A total of 5,477 patients were included, with a mean age of 72 years, 36.4% diabetic, and a mean baseline eGFR of 36 ml/min/1.73 m2. The rate of dialysis initiation was three events per 100 patient-years, 95% CI (2.9-3.6). The optimal cutoff for sensitivity was 0.94, for specificity, 0.76, and the area under the ROC curve was 0.92. Harrell's C-statistic was 0.88 for the total population, 0.88 for diabetic patients, and 0.93 for those 65 years or older. The validation of the model showed good calibration. Conclusions: In this Colombian cohort, the four-variable KFRE with a two-year prediction horizon has excellent calibration and discrimination, and its use in the care of CKD Colombian patients is recommended.

Epidemiología de la infección asociada a catéter venoso central / Epidemiology of infections of central venous catheters

Objetive: To identify the frequency of infections related to Central Cenous Catheters (CVC)in children and determine if the colonization of the line predicts infection. Patients and Methods. A longitudinal descriptive study of 109 CVC. Colonization was detected at the entry point and connection points of the lines with a semi quantitative method. Definitions were made according to CDC (Atlanta) Criteria. Results: The incidence of infection into the blood stream was 11 percent, density of incidence 9/1000 days/ catheter. Risk factors were identified: a) surgery (RR 4,2 IC95 percent 1,5-11,7), b) ostomies (RR 4,0 IC95 percent 1,4-11,4), and c) colonization in line connections (RR 3,9 IC95 percent 1,2-12,3). Agents identified were Staphylococcus coagulasa (-) 83,4 percent and Candida albicans 16,6 percent. Incidence of local infection was 5,5 percent. Sensitivity, specificity and (+) predictive value of cultures of cultures and connections were very low. Conclusions: In this experience, the incidence of infection associated to peripheral lines was quite high. Colonization of insertion and connections does not predict infection. The implementation of Bundle is recommended to prevent these infections.

Objetivo: Identificar frecuencia de infecciones relacionadas con catéter venoso central en niños y determinar si la colonización del catéter predice la infección. Pacientes y Métodos: Se hizo un estudio descriptivo longitudinal en 109 catéteres venosos centrales; se detectó colonización en sitio de entrada y conexiones de los catéteres con método semicuantitativo. Las definiciones se realizaron con los criterios de los Centros de Control de Enfermedades de Atlanta. Resultados: La Incidencia de infección del torrente sanguíneo fue 11 por ciento, la densidad de incidencia 9/1000 días/ catéter; se identificaron como factores de riesgo la cirugía (RR 4,2 IC95 por ciento 1,5-11,7), las ostomías (RR 4,0 IC95 por ciento 1,4-11,4) y la colonización en conexiones del catéter (RR 3,9 IC95 por ciento 1,2-12,3); fueron provocadas por Staphylococcus coagulasa (-) 83,4 por ciento y Candida albicans 16,6 por ciento. La incidencia de infección local fue de 5,5 por ciento. La sensibilidad, especificidad y valor predictivo (+) de los cultivos en inserción y conexiones fueron muy bajos. Conclusiones: En esta experiencia se encontró una elevada incidencia de infección asociada a catéteres de inserción periférica; la colonización de inserción y conexiones no fueron predictores de la infección; se recomienda implementar Bundle para prevención de estas infecciones.

Dialysis outcomes in Colombia (DOC) study: a comparison of patient survival on peritoneal dialysis vs hemodialysis in Colombia.

The goal of the Dialysis Outcomes in Colombia (DOC) study was to compare the survival of patients on hemodialysis (HD) vs peritoneal dialysis (PD) in a network of renal units in Colombia. The DOC study examined a historical cohort of incident patients starting dialysis therapy between 1 January 2001 and 1 December 2003 and followed until 1 December 2005, measuring demographic, socioeconomic, and clinical variables. Only patients older than 18 years were included. As-treated and intention-to-treat statistical analyses were performed using the Kaplan-Meier method and Cox proportional hazard model. There were 1094 eligible patients in total and 923 were actually enrolled: 47.3% started HD therapy and 52.7% started PD therapy. Of the patients studied, 751 (81.3%) remained in their initial therapy until the end of the follow-up period, death, or censorship. Age, sex, weight, height, body mass index, creatinine, calcium, and Subjective Global Assessment (SGA) variables did not show statistically significant differences between the two treatment groups. Diabetes, socioeconomic level, educational level, phosphorus, Charlson Co-morbidity Index, and cardiovascular history did show a difference, and were less favorable for patients on PD. Residual renal function was greater for PD patients. Also, there were differences in the median survival time between groups: 27.2 months for PD vs 23.1 months for HD (P=0.001) by the intention-to-treat approach; and 24.5 months for PD vs 16.7 months for HD (P<0.001) by the as-treated approach. When performing univariate Cox analyses using the intention-to-treat approach, associations were with age > or =65 years (hazard ratio (HR)=2.21; confidence interval (CI) 95% (1.77-2.755); P<0.001); history of cardiovascular disease (HR=1.96; CI 95% (1.58-2.90); P<0.001); diabetes (HR=2.34; CI 95% (1.88-2.90); P<0.001); and SGA (mild or moderate-severe malnutrition) (HR=1.47; CI 95% (1.17-1.79); P=0.001); but no association was found with gender (HR=1.03, CI 95% 0.83-1.27; P=0.786). Similar results were found with the as-treated approach, with additional associations found with Charlson Index (0-2) (HR=0.29; Cl 95% (0.22-0.38); P<0.001); Charlson Index (3-4) (HR=0.61; Cl 95% (0.48-0.79); P<0.001); and SGA (mild-severe malnutrition) (HR=1.43; Cl 95% (1.15-1.77); P<0.001). Similarly, the multivariate Cox model was run with the variables that had shown association in previous analyses, and it was found that the variables explaining the survival of patients with end-stage renal disease in our study were age, SGA, Charlson Comorbidity Index 5 and above, diabetes, healthcare regimes I and II, and socioeconomic level 2. The results of Cox proportional risk model in both the as-treated and intention-to-treat analyses showed that there were no statistically significant differences in survival of PD and HD patients: intention-to-treat HD/PD (HR 1.127; CI 95%: 0.855-1.484) and as-treated HD/PD (HR 1.231; CI 95%: 0.976-1.553). In this historical cohort of incident patients, there was a trend, although not statistically significant, for a higher (12.7%) adjusted mortality risk associated with HD when compared to PD, even though the PD patients were poorer, were more likely to be diabetic, and had higher co-morbidity scores than the HD patients. The variables that most influenced survival were age, diabetes, comorbidity, healthcare regime, socioeconomic level, nutrition, and education.

Potato Tuber UDP-Glucose:Protein Transglucosylase Catalyzes Its Own Glucosylation.

Potato (Solanum tuberosum L.) tuber UDP-glucose:protein transglucosylase (UPTG) (EC 2.4.1.112) is involved in the first of a two-step mechanism proposed for protein-bound alpha-glucan synthesis by catalyzing the covalent attachment of a single glucose residue to an acceptor protein. The resulting glucosylated 38-kilodalton polypeptide would then serve as a primer for enzymic glucan chain elongation during the second step. In the present report, we describe the fast protein liquid chromatography purification of UPTG from a membrane pellet of potato tuber. An apparently close association of UPTG, phosphorylase, and starch synthase was observed under native conditions during different purification steps. Enrichment of a 38-kilodalton polypeptide was found throughout enzyme purification. It is now shown that the purified UPTG, with an apparent molecular mass of 38 kilodaltons, undergoes self-glucosylation in a UDP-glucose- and Mn(2+)-dependent reaction. Therefore, it is concluded that UPTG is the enzyme and at the same time the priming protein required for the biogenesis of protein-bound alpha-glucan in potato tuber.

A method for accurate analysis of intermembrane space in organelles enclosed by double envelope membranes.

Centrifugal filtration through a double layer of silicone oil was applied to determine the intermembrane space of organelles enclosed by double envelope membranes, i.e. proplastids, chloroplasts, mitochondria and amyloplasts. The organelles, capable of transporting adenylates by an adenylate translocator located in the inner envelope membrane, were incubated with increasing concentrations of adenylates while maintaining their specific radioactivities constant. Intermembrane spaces were estimated by extrapolation of radioactivities recovered after filtration of the organelles. The values estimated were compared to those obtained employing the classical method measuring the intake of [14C]-sucrose and [14C]-sorbitol which are impermeable to the inner membranes of organelles. The intermembrane space determined by the present method was shown to be uniformly smaller than the sucrose-permeable space which was always smaller than the sorbitol-permeable space.

ADP-Glucose Transport by the Chloroplast Adenylate Translocator Is Linked to Starch Biosynthesis.

In organello starch biosynthesis was studied using intact chloroplasts isolated from spinach leaves (Spinacia oleracea). Immunoblot analysis using a specific antiserum against the mitochondrial adenylate (ADP/ATP) translocator of Neurospora crassa shows the presence of an adenylate translocator protein in the chloroplast envelope membranes, similar to that existing in mitochondria and amyloplasts from cultured cells of sycamore (Acer pseudoplatanus). The double silicone oil layer-filtering centrifugation technique was employed to study the kinetic properties of adenylate transport in the purified chloroplasts; ATP, ADP, AMP, and most importantly ADP-Glc were shown to be recognized by the adenylate translocator. Similar to the situation with sycamore amyloplasts, only ATP and ADP-Glc uptake was inhibited by carboxyatractyloside, an inhibitor of the mitochondrial adenylate translocator. Evidence is presented to show that the ADP-Glc transported into the chloroplast stroma is utilized for starch synthesis catalyzed by starch synthase (ADP-Glc:1,4-alpha-d-glucan 4-alpha-d-glucosyltransferase). The high activity of sucrose synthase producing ADP-Glc observed in the extrachloroplastic fractions suggests that starch biosynthesis in chloroplasts may be coupled with the direct import of ADP-Glc from the cytosol.