Ipsilateral proximal and shaft femoral fractures: Results of two treatment strategies / Fracturas ipsilaterales proximales y diafisarias del fémur: resultados de 2 estrategias de tratamiento

Introduction: Ipsilateral proximal and shaft femoral fractures typically occur in young adults after high-energy trauma. No consensus exists regarding the optimal internal fixation device or surgical strategy for these complex fractures. Our main objective is to identify differences on outcomes and complications between patients treated with one or combined implants. Material and method: This is a single-center retrospective cohort study in patients with associated fractures of the proximal (31 AO) and shaft femur (32 AO). We divided the patients into two groups according to the use of single (Group I) or combined implants (Group II). Demographic, clinical, radiological, surgical data and development of complications were collected.Results: We identified 28 patients (19 men and 9 women) with an average age of 43 years. We used an anterograde femoral nail in group I (17 patients) and a retrograde femoral nail or a plate associated with hip lag screws or sliding hip screw in Group II (11 patients). Patients were followed up for 26.28 (9.12–62.88) months. Osteonecrosis of the femoral head, osteoarthritis, infection or nonunion was found in 9 patients (32%). No significant differences (p 0.70) were found in complications between two groups or between definitive surgical fixation before or after the first 24h. Conclusions: No differences in the development of complications or timing of definitive fixation were found between the use of one or combined implants in ipsilateral proximal femur and shaft fractures. Regardless of the implant chosen, an appropriate osteosynthesis technique is crucial, even so high complication rates are expected.

Introducción: Las fracturas ipsilaterales proximales y diafisarias del fémur suelen ocurrir en adultos jóvenes después de un traumatismo de alta energía. No existe consenso sobre el dispositivo de fijación interna óptimo o la estrategia quirúrgica para estas fracturas complejas. Nuestro principal objetivo es identificar las diferencias en los resultados y complicaciones entre los pacientes tratados con un implante o combinados. Material y método: Este es un estudio de cohorte retrospectivo unicéntrico en pacientes con fracturas asociadas del fémur proximal (31 AO) y diafisarias (32 AO). Dividimos a los pacientes en 2 grupos según el uso de implantes únicos (grupo i) o combinados (grupo ii). Se recogieron datos demográficos, clínicos, radiológicos, quirúrgicos y complicaciones. Resultados: Se identificaron 28 pacientes (19 hombres y 9 mujeres) con una edad promedio de 43 años. Utilizamos un clavo femoral anterógrado en el grupo i (17 pacientes) y un clavo femoral retrógrado o una placa con tornillos a compresión o tornillo deslizante de cadera en el grupo ii (11 pacientes). Los pacientes fueron seguidos durante 26,28 (9,12-62,88) meses. Se encontró osteonecrosis de la cabeza femoral, osteoartritis, infección o seudoartrosis en 9 pacientes (32%). No se encontraron diferencias significativas (p=0,70) en las complicaciones entre los 2 grupos o entre la fijación quirúrgica definitiva antes o después de las primeras 24h. Conclusiones: No se encontraron diferencias en el desarrollo de complicaciones o el momento de la fijación definitiva entre el uso de un implante o combinado en fracturas ipsilaterales de fémur proximal y diafisario. Independientemente del implante elegido, una técnica de osteosíntesis adecuada es crucial; aun así son esperables altas tasas de complicaciones.(AU)

[Artículo traducido] Fracturas ipsilaterales proximales y diafisarias del fémur: resultados de dos estrategias de tratamiento / Ipsilateral proximal and shaft femoral fractures: Results of two treatment strategies

Introduction: Ipsilateral proximal and shaft femoral fractures typically occur in young adults after high-energy trauma. No consensus exists regarding the optimal internal fixation device or surgical strategy for these complex fractures. Our main objective is to identify differences on outcomes and complications between patients treated with one or combined implants. Material and method: This is a single-center retrospective cohort study in patients with associated fractures of the proximal (31 AO) and shaft femur (32 AO). We divided the patients into two groups according to the use of single (Group I) or combined implants (Group II). Demographic, clinical, radiological, surgical data and development of complications were collected.Results: We identified 28 patients (19 men and 9 women) with an average age of 43 years. We used an anterograde femoral nail in group I (17 patients) and a retrograde femoral nail or a plate associated with hip lag screws or sliding hip screw in Group II (11 patients). Patients were followed up for 26.28 (9.12–62.88) months. Osteonecrosis of the femoral head, osteoarthritis, infection or nonunion was found in 9 patients (32%). No significant differences (p 0.70) were found in complications between two groups or between definitive surgical fixation before or after the first 24h. Conclusions: No differences in the development of complications or timing of definitive fixation were found between the use of one or combined implants in ipsilateral proximal femur and shaft fractures. Regardless of the implant chosen, an appropriate osteosynthesis technique is crucial, even so high complication rates are expected.

Introducción: Las fracturas ipsilaterales proximales y diafisarias del fémur suelen ocurrir en adultos jóvenes después de un traumatismo de alta energía. No existe consenso sobre el dispositivo de fijación interna óptimo o la estrategia quirúrgica para estas fracturas complejas. Nuestro principal objetivo es identificar las diferencias en los resultados y complicaciones entre los pacientes tratados con un implante o combinados. Material y método: Este es un estudio de cohorte retrospectivo unicéntrico en pacientes con fracturas asociadas del fémur proximal (31 AO) y diafisarias (32 AO). Dividimos a los pacientes en 2 grupos según el uso de implantes únicos (grupo i) o combinados (grupo ii). Se recogieron datos demográficos, clínicos, radiológicos, quirúrgicos y complicaciones. Resultados: Se identificaron 28 pacientes (19 hombres y 9 mujeres) con una edad promedio de 43 años. Utilizamos un clavo femoral anterógrado en el grupo i (17 pacientes) y un clavo femoral retrógrado o una placa con tornillos a compresión o tornillo deslizante de cadera en el grupo ii (11 pacientes). Los pacientes fueron seguidos durante 26,28 (9,12-62,88) meses. Se encontró osteonecrosis de la cabeza femoral, osteoartritis, infección o seudoartrosis en 9 pacientes (32%). No se encontraron diferencias significativas (p=0,70) en las complicaciones entre los 2 grupos o entre la fijación quirúrgica definitiva antes o después de las primeras 24h. Conclusiones: No se encontraron diferencias en el desarrollo de complicaciones o el momento de la fijación definitiva entre el uso de un implante o combinado en fracturas ipsilaterales de fémur proximal y diafisario. Independientemente del implante elegido, una técnica de osteosíntesis adecuada es crucial; aun así son esperables altas tasas de complicaciones.(AU)

Ipsilateral proximal and shaft femoral fractures: Results of two treatment strategies.

INTRODUCTION: Ipsilateral proximal and shaft femoral fractures typically occur in young adults after high-energy trauma. No consensus exists regarding the optimal internal fixation device or surgical strategy for these complex fractures. Our main objective is to identify differences on outcomes and complications between patients treated with one or combined implants. MATERIAL AND METHOD: This is a single-center retrospective cohort study in patients with associated fractures of the proximal (31 AO) and shaft femur (32 AO). We divided the patients into two groups according to the use of single (Group I) or combined implants (Group II). Demographic, clinical, radiological, surgical data and development of complications were collected. RESULTS: We identified 28 patients (19 men and 9 women) with an average age of 43 years. We used an anterograde femoral nail in group I (17 patients) and a retrograde femoral nail or a plate associated with hip lag screws or sliding hip screw in Group II (11 patients). Patients were followed up for 26.28 (9.12-62.88) months. Osteonecrosis of the femoral head, osteoarthritis, infection or nonunion was found in 9 patients (32%). No significant differences (p 0.70) were found in complications between two groups or between definitive surgical fixation before or after the first 24h. CONCLUSIONS: No differences in the development of complications or timing of definitive fixation were found between the use of one or combined implants in ipsilateral proximal femur and shaft fractures. Regardless of the implant chosen, an appropriate osteosynthesis technique is crucial, even so high complication rates are expected. LEVEL OF EVIDENCE: IV. Grade of Recommendation: C.

Usefulness of the Nasal Allergen Provocation Test in the Diagnosis of Shellfish Allergy.

BACKGROUND AND OBJECTIVES: Shellfish allergy is a major cause of food allergy and anaphylaxis worldwide. Several allergenic proteins have been described in the last few years, but the only diagnostic tool that still enables discrimination between allergic and nonallergic sensitized persons is the oral food challenge (OFC). The aim of this study was to evaluate the usefulness of the nasal allergen provocation test (NAPT) as a diagnostic tool in shellfish allergy. METHODS: Forty-five patients with confirmed sensitization to shrimp by a positive skin prick test (SPT) result with a commercial shrimp extract were recruited and classified as sensitized-allergic or sensitized-nonallergic based on current tolerance to shrimp intake, the result of an OFC with a freeze-dried cooked shrimp mixture extract, or a recent history of anaphylaxis induced by shrimp ingestion. These patients and 10 controls not sensitized to shrimp underwent NAPT with a freeze-dried cooked shrimp mixture extract. The response was evaluated using acoustic rhinometry and a visual analog scale. RESULTS: Significant differences (P=.001) were found between the sensitized-allergic group (18/20 positive NAPT, 90%) and both the sensitized-nonallergic group (2/18 positive NAPT, 11.1%) and controls (0/10 positive NAPT). NAPT enables differentiation between allergic and nonallergic persons with a sensitivity of 90%, specificity of 89%, positive predictive value of 90%, and negative predictive value of 89%. CONCLUSIONS: Our results indicate that NAPT makes it possible to differentiate between sensitized symptomatic patients and sensitized tolerant patients and could be a valuable diagnostic tool when assessing shrimp allergy.

Usefulness of the Nasal Allergen Provocation Test in the Diagnosis of Shellfish Allergy

Background: Shellfish allergy is a major cause of food allergy and anaphylaxis worldwide. Several allergenic proteins have been described in the last few years, but the only diagnostic tool that still enables discrimination between allergic and nonallergic sensitized persons is the oral food challenge (OFC). Objective: The aim of this study was to evaluate the usefulness of the nasal allergen provocation test (NAPT) as a diagnostic tool in shellfish allergy. Methods: Forty-five patients with confirmed sensitization to shrimp by a positive skin prick test (SPT) result with a commercial shrimp extract were recruited and classified as sensitized-allergic or sensitized-nonallergic based on current tolerance to shrimp intake, the result of an OFC with a freeze-dried cooked shrimp mixture extract, or a recent history of anaphylaxis induced by shrimp ingestion. These patients and 10 controls not sensitized to shrimp underwent NAPT with a freeze-dried cooked shrimp mixture extract. The response was evaluated using acoustic rhinometry and a visual analog scale. Results: Significant differences (P=.001) were found between the sensitized-allergic group (18/20 positive NAPT, 90%) and both the sensitized-nonallergic group (2/18 positive NAPT, 11.1%) and controls (0/10 positive NAPT). NAPT enables differentiation between allergic and nonallergic persons with a sensitivity of 90%, specificity of 89%, positive predictive value of 90%, and negative predictive value of 89%. Conclusions: Our results indicate that NAPT makes it possible to differentiate between sensitized symptomatic patients and sensitized tolerant patients and could be a valuable diagnostic tool when assessing shrimp allergy (AU)

Shellfish Allergy: Unmet Needs in Diagnosis and Treatment.

Seafood is a major cause of food allergy and anaphylaxis worldwide. Shellfish is included among the "big eight" food groups, which are responsible for more than 90% of all cases of food allergy. Approximately 2.5% of the world's population has experienced an adverse reaction to seafood. Seafood allergy is one of the most frequent and lethal allergies that exist. The several allergenic proteins involved in allergic reactions that have been described in recent years include tropomyosin, arginine kinase, myosin light chain, and sarcoplasmic calcium-binding protein. Despite all the data reported in the last few years, shellfish allergy is still diagnosed and treated as it was 50 years ago. The only effective treatment to prevent allergic reactions to shellfish is avoidance. This review aims to update recently published data on shellfish allergy and to highlight those areas that have yet to be resolved.

Termólisis facetaria por radiofrecuencia en el dolor dorso lumbar crónico / Facet radiofrequency thermolysis in chronic thoracolumbar pain

Objetivo: Evaluar la seguridad de la termólisis facetaria por radiofrecuencia en el tratamiento del dolor dorsolumbar crónico. Materiales y métodos: Entre julio de 2013 y julio de 2014, se analizaron retrospectivamente 12 pacientes con dolor dorsolumbar crónico de tipo facetario, a los que se les había realizado previamente un bloqueo bajo tomografía computada (TC). Se evaluaron las complicaciones inmediatas y tardías, registrándose también la mejoría de síntomas de forma directa (escala visual analógica) e indirecta (consumo de medicación). Resultados: Hubo menos de un 20% de complicaciones tempranas leves, todas autolimitadas. No se constataron complicaciones tempranas graves ni tardías. A los tres meses del procedimiento se confirmó un descenso del dolor en el 83% de los casos (n = 10), con una supresión total de la ingesta de medicamentos en un 25% (n = 3) y una reducción de la misma en un 58% (n = 7) de los pacientes. Discusión: A pesar del número reducido de pacientes de nuestro estudio, los resultados en cuanto a la seguridad y el éxito del procedimiento fueron muy similares a los reportados en otros trabajos con mayor casuística. La mejora se vio reflejada no solo en la reducción del dolor, sino también en la menor ingesta de analgésicos. Conclusión: La termólisis facetaria por radiofrecuencia es un método seguro y útil, con un bajo porcentaje de complicaciones que pueden manejarse ambulatoriamente

Objective: To evaluate the safety of facet-dependent radiofrequency thermolysis for the treat-ment of chronic thoracolumbar pain. Materials and methods: A retrospective analysis was performed on 12 patients with chronic thoracolumbar pain of facet type, who had previously undergone a radicular blockage using computed tomography (CT), in the period between July 2013 and July 2014. Inmediateand delayed complications where assessed. Improvement of symptoms was also assessed, both directly (visual analogue scale), and indirectly (reduction in pain relief medication). Results: Self-limited early complications were noted in 20% of the patients. No late nor serious complications were reported. Three months after the procedure was performed, pain relief was observed in 83% of the cases (n= 10), with absolute reduction in pain relief medication in 25% (n = 3) of the patients, and a partial reduction in 58% (n = 7). Discussion: In spite of the reduced number of patients in our study, the results were similar to other publications with larger populations in regard to safety and procedure success. Improvement was not only reflected by the reporting of reduced pain, but it was also observed in a reduced intake of pain relief medications. Conclusión: Our study shows that facet-dependent radiofrequency thermolysis is a safe and useful method, with low complication rates, that can be managed on an outpatient basis

Partial least squares regression: a valuable method for modeling molecular behavior in hemodialysis.

The aim of this work was to use the Partial Least Squares Regression (PLS) technique to fit simple models for the interpretation of an underlying complex process. In this study, the technique was used to build a statistical model for molecular kinetic data obtained from hemodialyzed patients. By using PLS we derived statistical linear models for the prediction of the equilibrated urea concentration which would be reached 30-60 min after the end of the dialysis session. Models with an average relative prediction error (RPE) of less than 0.05% were achieved. The model predictive accuracy was evaluated in a cross-center study yielding an RPE < 3%. The chosen model was robust to variations such as sampling extraction time demonstrating a high capacity for modeling kinetics. It also was found to be useful for bedside monitoring. Finally, the PLS technique allowed identification of the most important co-variables in the model and of those patients with outlier patterns in their molecular dynamics.

The use of homeopathic combination remedy for dengue fever symptoms: a pilot RCT in Honduras.

A double-blind, placebo-controlled randomized trial of a homeopathic combination medication for dengue fever was carried out in municipal health clinics in Honduras. Sixty patients who met the case definition of dengue (fever plus two ancillary symptoms) were randomized to receive the homeopathic medication or placebo for 1 week, along with standard conventional analgesic treatment for dengue. The results showed no difference in outcomes between the two groups, including the number of days of fever and pain as well as analgesic use and complication rates. Only three subjects had laboratory confirmed dengue. An interesting sinusoidal curve in reported pain scores was seen in the verum group that might suggest a homeopathic aggravation or a proving. The small sample size makes conclusions difficult, but the results of this study do not suggest that this combination homeopathic remedy is effective for the symptoms that are characteristic of dengue fever.

Comparison of different methods for hemodialysis evaluation by means of ROC curves: from artificial intelligence to current methods.

BACKGROUND: The National Kidney Foundation Guidelines (DOQI) and the European Renal Association (ERA) have set standards for adequacy of hemodialysis treatment. They recommended minimum single pool doses of 1.2 (Kt/Vsp DOQI), and 1.4 (Kt/Vsp ERA) and a "standard" urea removal ratio (URR) of 65%. Here, we compare an Artificial Intelligence Method (AIM) based on an Artificial Neural Network (ANN) and the usual methods for hemodialysis treatment follow-up such as Smye, Daugirdas, standard urea reduction ratio (URR using post-dialysis urea concentration) and modified URR [Cheng et al. 2001] against equilibrated Kt/V and URR calculated using a 60 min post-dialysis urea concentration. METHODS: We used ROC analysis to evaluate and compare these methodologies. We also propose a method to find a minimum target dose that maximizes the sensitivity, specificity and positive predictive values of the diagnostic tool. RESULTS: From a URR point of view, the ANN, stdURR and mURR perform almost equally well with an area under the curve (AUC) of 0.90, 0.93 and 0.92, respectively, but the ANN achieved the lowest false positive rate (FPR = 7.94%) and error rate (ER = 12.7%). When Kt/V is used as a dose index, the logarithmic single-and double-pool equations perform almost equally (AUC 0.957 and 0.962), and the ANN method achieves an AUC of 0.934. The lowest FPR was for ANN and Kt/Vsp (4.76%), which also achieved the lowest ER of 6.39%. CONCLUSIONS: For both cases (URR and Kt/V), the minimum doses required to achieve the lowest FPR and ER for the standard methods (stdURR and Kt/Vsp) were higher than those reported by the DOQI guidelines, being 70% for stdURR and 1.35 for Kt/Vsp, whereas for those methods using the double-pool Kt/V or equilibrated URR, the dose targets were close to those recommended by DOQI and ERA. Our proposed method for target dose selection is easy to understand, and it takes into account both accuracy and confidence of the adequacy tool. We found the ANN method to be superior to the Smye method for estimation of equilibrated urea, and the results presented here suggest that ANN methods could be useful tools in the analysis of nephrology data.

Dialysate-side urea kinetics. Neural network predicts dialysis dose during dialysis.

Determination of the adequacy of dialysis is a routine but crucial procedure in patient evaluation. The total dialysis dose, expressed as Kt/V, has been widely recognised to be a major determinant of morbidity and mortality in haemodialysed patients. Many different factors influence the correct determination of Kt/V, such as urea sequestration in different body compartments, access and cardiopulmonary recirculation. These factors are responsible for urea rebound after the end of the haemodialysis session, causing poor Kt/V estimation. There are many techniques that try to overcome this problem. Some of them use analysis of blood-side urea samples, and, in recent years, on-line urea monitors have become available to calculate haemodialysis dose from dialysate-side urea kinetics. All these methods require waiting until the end of the session to calculate the Kt/V dose. In this work, a neural network (NN) method is presented for early prediction of the Kt/V dose. Two different portions of the dialysate urea concentration-time profile (provided by an on-line urea monitor) were analysed: the entire curve A and the first half B, using an NN to predict the Kt/V and compare this with that provided by the monitor. The NN was able to predict Kt/V is the middle of the 4h session (B data) without a significant increase in the percentage error (B data: 6.69% +/- 2.46%; A data: 5.58% +/- 8.77%, mean +/- SD) compared with the monitor Kt/V.

Detection of abnormality in the electrocardiogram without prior knowledge by using the quantisation error of a self-organising map, tested on the European ischaemia database.

Most systems for the automatic detection of abnormalities in the ECG require prior knowledge of normal and abnormal ECG morphology from pre-existing databases. An automated system for abnormality detection has been developed based on learning normal ECG morphology directly from the patient. The quantisation error from a self-organising map 'learns' the form of the patient's ECG and detects any change in its morphology. The system does not require prior knowledge of normal and abnormal morphologies. It was tested on 76 records from the European Society of Cardiology database and detected 90.5% of those first abnormalities declared by the database to be ischaemic. The system also responded to abnormalities arising from ECG axis changes and slow baseline drifts and revealed that ischaemic episodes are often followed by long-term changes in ECG morphology.

Using artificial intelligence to predict the equilibrated postdialysis blood urea concentration.

Total dialysis dose (Kt/V) is considered to be a major determinant of morbidity and mortality in hemodialyzed patients. The continuous growth of the blood urea concentration over the 30- to 60-min period following dialysis, a phenomenon known as urea rebound, is a critical factor in determining the true dose of hemodialysis. The misestimation of the equilibrated (true) postdialysis blood urea or equilibrated Kt/V results in an inadequate hemodialysis prescription, with predictably poor clinical outcomes for the patients. The estimation of the equilibrated postdialysis blood urea (eqU) is therefore crucial in order to estimate the equilibrated (true) Kt/V. In this work we propose a supervised neural network to predict the eqU at 60 min after the end of hemodialysis. The use of this model is new in this field and is shown to be better than the currently accepted methods (Smye for eqU and Daugirdas for eqKt/V). With this approach we achieve a mean difference error of 0.22 +/- 7.71 mg/ml (mean % error: 1.88 +/- 13.46) on the eqU prediction and a mean difference error for eqKt/V of -0.01 +/- 0.15 (mean % error: -0.95 +/- 14.73). The equilibrated Kt/V estimated with the eqU calculated using the Smye formula is not appropriate because it showed a great dispersion. The Daugirdas double-pool Kt/V estimation formula appeared to be accurate and in agreement with the results of the HEMO study.

Trial of a community-based intervention to decrease infestation of Aedes aegypti mosquitoes in cement washbasins in El Progreso, Honduras.

Washbasins and metal drums are important sources of Aedes aegypti mosquitoes in much of Latin America. When manual cleaning was found to be ineffective in eliminating mosquito larvae in a community-based control programme in El Progreso, Honduras, it was decided to develop and evaluate an improved method of removing mosquito eggs based on commonly-available materials. The method, named La Untadita ('The Little Dab', in English), consists of five steps: mixing chlorine bleach and detergent to make a paste, applying the mixture to the walls of the container, waiting 10 min, scrubbing with a brush, and finally rinsing with water. A field trial of the Untadita was conducted in 13 peri-urban neighbourhoods. At the first post-intervention survey, in spite of high levels of exposure to the community-based intervention, high levels of knowledge regarding the Untadita and high levels of its reported use, little or no impact was discernable on mosquito larvae and pupae. The method was then modified by increasing the recommended quantities of bleach and detergent and simplifying the instructions. In the second post-intervention survey, knowledge of the steps and their order increased further; the intervention neighbourhoods had significantly fewer algae on washbasin walls, an indicator of more effective cleaning; and numbers of pupae and 3rd and 4th instar larvae were significantly lower than in untreated neighbourhoods. Effective promotion of the Untadita should be able to control mosquito infestation in many washbasins, especially those in frequent use, thus reducing the need for chemical and biological larvicides that may be either more costly or less acceptable to householders.

Development of an indicator to evaluate the impact, on a community-based Aedes aegypti control intervention, of improved cleaning of water-storage containers by householders.

Householders in a community-based programme to control dengue in El Progreso, Honduras, are being encouraged to improve the cleaning of the water-storage containers in which many of the vectors thrive. The objective of the present study was to develop an indicator of the change occurring in human behaviour. Traditional Aedes aegypti larval indices do not differentiate between containers in which all the immature stages are present and those which hold only first- and second-instar larvae. However, it is not essential to prevent all larval development to limit transmission of pathogens by the adults; if the Ae. aegypti in the containers only manage to develop to young larvae before the containers are cleaned, then control of the vector in these containers will be effective. In field trials, sampling of third- and fourth-instar larvae in washbasins by taking five dips (quick immersions to a standard depth) with a hand-held net was found to be sufficient for estimating the true population size of that same cohort. This sampling method was then included in a large-scale survey of households, conducted for programme monitoring. An index was then developed as a summary measure of the degree of infestation of a washbasin by Ae. aegypti. This index was the sum of four variables assessed in the survey: presence of any immature stages (larvae and/or pupae); presence of pupae; detection of third-fourth-instar larvae in a five-dip sample; and a log-transformation of the number of larvae recovered. Based on this new index, the 884 washbasins encountered in the survey were classified as infestation-free (76.2%), or with low-(6.7%), medium-(14.9%) or high-level (2.2%) infestation. Application of the same procedure to 240 drums encountered in the survey showed that 66.3% were infestation-free and 9.2%, 17.1% and 7.4% had low-, medium- and high-level infestations, respectively. Compared with the traditional indices, this new index should be more sensitive to changes in human behaviour resulting from a control programme exposure than a simple, dichotomous variable (i.e. positive/negative for presence of immature stages). The use of such an index could make the control programme more efficient, allowing the greatest efforts to be targeted at households that have medium-high levels of infestation.

La Untadita: a procedure for maintaining washbasins and drums free of Aedes aegypti based on modification of existing practices.

Chlorine bleach and detergent are routinely used by householders in El Progreso, Honduras in the process of cleaning washbasins and drums, the two most important larval habitats of Aedes aegypti in the city. The efficacy of these materials in eliminating eggs, larvae, and pupae of Ae. aegypti was assessed under controlled conditions. The promising results obtained led to trials using a combination of chlorine bleach and detergent to apply to the walls of washbasins and drums as a method for eliminating eggs. The bleach maintained its ovicidal properties when mixed with detergent, and the detergent gave the mixture consistency so that it could be applied as a thin film to the walls. This new procedure was named the little dab (Untadita in Spanish) and allows households to direct their efforts against a stage of the mosquito life cycle that has been ignored in the past: the egg.

Macromolecular domains containing nuclear protein p107 and U-snRNP protein p28: further evidence for an in situ nuclear matrix.

Polyclonal antibodies have been produced which react with a nuclear protein having a molecular weight of 107kD and a pI of 8.7-8.8 (designated p107). This protein is shown to be a component of the residual ribonucleoprotein (RNP) network of the nuclear matrix. P107 localized exclusively to the nuclear interior but not within nucleolar or chromatin domains. We have taken advantage of this unique probe to examine whether the RNP network of the isolated nuclear matrix has a physical counterpart in situ. We show that RNA, p107, divalent cations and the 28 kD Sm antigen of U-snRNPs are components of in situ macromolecular assemblies. While the morphology and intranuclear distribution of these assemblies are insensitive to the removal of chromatin, they are markedly altered by degradation of RNA. Digestion in situ of RNA in the presence of EDTA followed by extraction with high ionic strength buffers solubilized the components of these assemblies. Electron microscopic and immunobiochemical data are presented which support the concept that the residual RNP network of the nuclear matrix is an isolate of a pre-existing structure, and that perturbations in this internal network can be created by RNA degradation, depletion of essential metal ions and proteolysis.