Case-control study assessing the impact of COVID19 in advanced kidney cancer patients treated with antiangiogenics or immunotherapy: the COVID-REN study

BACKGROUND

Cancer is a risk factor for developing severe COVID19. Additionally, SARS-CoV2 has a special tropism for renal cells and complications like thrombosis or cytokine storm could be enhanced by standard treatments in kidney cancer (i.e., antiangiogenics or immunotherapy). Thus, understanding the impact of COVID19 in patients with this tumor is key for their correct management.

METHODS

We designed a retrospective case-control study comparing the outcome of three groups of advanced kidney cancer patients on systemic treatment: cohort A (developed COVID19 while on antiangiogenics), cohort B (developed COVID19 while on immunotherapy) and cohort C (non-infected). Matching factors were age, gender, and treatment.

RESULTS

95 patients were recruited in 16 centers in Spain from September 2020 to May 2021. Finally, 85 were deemed as eligible (23 cohort A, 21 cohort B, 41 cohort C). Patients with COVID required more dose interruptions (25 vs. six) and hospitalizations (10 vs. none) than those without COVID (both p = 0.001). No difference between cohorts A and B was observed regarding hospitalization or length of stay. No ICU admission was registered and one patient in cohort B died due to COVID19. Regarding cancer evolution, three patients in cohort A presented progressive disease after COVID19 compared to two in cohort B. One case in cohort B, initially deemed as stable disease, achieved a partial response after COVID19.

CONCLUSIONS

Kidney cancer patients who developed COVID19 while on systemic therapy required more treatment interruptions and hospitalizations than those non-infected. However, no significant impact on cancer outcome was observed. Also, no difference was seen between cases on antiangiogenics or immunotherapy.

Quantifying COVID-19's silver lining: Avoided deaths from air quality improvements in Bogotá

In cities around the world, COVID-19 lockdowns have significantly improved outdoor air quality. Even if only temporary, these improvements could have longer-lasting effects by making chronic air pollution more salient and boosting political pressure for change. To that end, it is important to develop objective estimates of both the air quality improvements associated with lockdowns and the benefits they generate. We use panel data econometric models to estimate the effect of Bogotá's 16-month lockdown on PM_2.5 and NO₂ pollution, epidemiological models to simulate the effect of reductions in these pollutants on long- and short-term mortality, and benefit transfer methods to value the avoided mortality. We find that on average, Bogotá's lockdown cut PM_2.5 pollution by 15% and NO₂ pollution by 21%. However, the magnitude of these effects varied considerably over time and across the city's neighborhoods. Equivalent permanent reductions in these pollutants would reduce long-term premature deaths from air pollution by 23% each year, a benefit valued at $1 billion annually. Finally, we estimate that if they occurred ceteris paribus, the temporary reductions in pollutant concentrations in 2020-2021 due to Bogotá's lockdown would have cut short-term deaths from air pollution by 19%, a benefit valued at $244 million.

EFECTO IN VITRO DEL EXTRACTO ETANÓLICO DE CAULERPA FILIFORMIS EN PARÁMETROS SEMINALES HUMANOS

El objetivo de este estudio fue determinar el efecto in vitro del extracto etanólico de Caulerpa filiformis en parámetros seminales  humanos. Se realizaron las siguientes pruebas: vitalidad, motilidad y dispersión de cromatina espermática; tomándose en cuenta las  variables tiempo (5’, 15’, 35’ y 60’) y concentración (0.04mg/ml, 0.4mg/ml y 4 mg/ml) para cada prueba. La muestra fue diluida hasta una concentración de 10 x 106 de espermatozoides/ml con suero fisiológico al 0.9%, luego incubada 1:1 (v/v) con el extracto. Con respecto a la vitalidad, a partir de los 15 minutos el extracto produjo mortalidad espermática. La DL50 fue de 17.35 mg/ml (11.08-57.17 mg/ml), 8.75 mg/ml (7.15-12.00 mg/ml) y 6.43 mg/ml (5.53-8.02 mg/ml) para los 15’, 35’ y 60’, respectivamente. En cuanto a la motilidad espermática se observó una disminución significativa con respecto al control en la concentración de 4mg/ml en los 15’ y 35’. A los 60’ en dicha concentración, todas las repeticiones alcanzaron una inmovilización espermática total. La CE50 a los 60’ fue de 0.49 mg/ml (-1.25-1.16 mg/ml). La prueba de ANOVA de 2 vías mostróque tanto el porcentaje de mortalidad como de espermatozoides inmovilizados se vio afectado por las variables tiempo y concentración, mientras que la interacción de éstas solo afectó la motilidad. El parámetro motilidad solo muestra un efecto dosis dependiente en la concentración de 4 mg/ml. La fragmentación de ADN no se vio afectada por ninguna de las variables ya mencionadas ni por la interacción de estas. Los resultados obtenidos con el extracto etanólico de Caulerpa filiformis podrían tener una naturaleza contraceptiva promisoria, y tal vez ser tomada en cuenta como una alternativa a los espermicidas comerciales, para ello se necesitará futuros estudios que develen la composición química de esta especie.

Inflammation, glucose, and vascular cell damage: the role of the pentose phosphate pathway

BACKGROUND

Hyperglycemia is acknowledged as a pro-inflammatory condition and a major cause of vascular damage. Nevertheless, we have previously described that high glucose only promotes inflammation in human vascular cells previously primed with pro-inflammatory stimuli, such as the cytokine interleukin (IL)1β. Here, we aimed to identify the cellular mechanisms by which high glucose exacerbates the vascular inflammation induced by IL1β.

METHODS

Cultured human aortic smooth muscle cells (HASMC) and isolated rat mesenteric microvessels were treated with IL1β in medium containing 5.5-22 mmol/L glucose. Glucose uptake and consumption, lactate production, GLUT1 levels, NADPH oxidase activity and inflammatory signalling (nuclear factor-κB activation and inducible nitric oxide synthase expression) were measured in HASMC, while endothelium-dependent relaxations to acetylcholine were determined in rat microvessels. Pharmacological inhibition of IL1 receptors, NADPH oxidase and glucose-6-phosphate dehydrogenase (G6PD), as well as silencing of G6PD, were also performed. Moreover, the pentose phosphate pathway (PPP) activity and the levels of reduced glutathione were determined.

RESULTS

We found that excess glucose uptake in HASMC cultured in 22 mM glucose only occurred following activation with IL1β. However, the simple entry of glucose was not enough to be deleterious since over-expression of the glucose transporter GLUT1 or increased glucose uptake following inhibition of mitochondrial respiration by sodium azide was not sufficient to trigger inflammatory mechanisms. In fact, besides allowing glucose entry, IL1β activated the PPP, thus permitting some of the excess glucose to be metabolized via this route. This in turn led to an over-activation NADPH oxidase, resulting in increased generation of free radicals and the subsequent downstream pro-inflammatory signalling. Moreover, in rat mesenteric microvessels high glucose incubation enhanced the endothelial dysfunction induced by IL1β by a mechanism which was abrogated by the inhibition of the PPP.

CONCLUSIONS

A pro-inflammatory stimulus like IL1β transforms excess glucose into a vascular deleterious agent by causing an increase in glucose uptake and its subsequent diversion into the PPP, promoting the pro-oxidant conditions required for the exacerbation of pro-oxidant and pro-inflammatory pathways. We propose that over-activation of the PPP is a crucial mechanism for the vascular damage associated to hyperglycemia.

The interleukin-1 receptor antagonist anakinra improves endothelial dysfunction in streptozotocin-induced diabetic rats

Background

Endothelial dysfunction is a crucial early phenomenon in vascular diseases linked to diabetes mellitus and associated to enhanced oxidative stress. There is increasing evidence about the role for pro-inflammatory cytokines, like interleukin-1β (IL-1β), in developing diabetic vasculopathy. We aimed to determine the possible involvement of this cytokine in the development of diabetic endothelial dysfunction, analysing whether anakinra, an antagonist of IL-1 receptors, could reduce this endothelial alteration by interfering with pro-oxidant and pro-inflammatory pathways into the vascular wall.

Results

In control and two weeks evolution streptozotocin-induced diabetic rats, either untreated or receiving anakinra, vascular reactivity and NADPH oxidase activity were measured, respectively, in isolated rings and homogenates from mesenteric microvessels, while nuclear factor (NF)-κB activation was determined in aortas. Plasma levels of IL-1β and tumor necrosis factor (TNF)-α were measured by ELISA. In isolated mesenteric microvessels from control rats, two hours incubation with IL-1β (1 to 10 ng/mL) produced a concentration-dependent impairment of endothelium-dependent relaxations, which were mediated by enhanced NADPH oxidase activity via IL-1 receptors. In diabetic rats treated with anakinra (100 or 160 mg/Kg/day for 3 or 7 days before sacrifice) a partial improvement of diabetic endothelial dysfunction occurred, together with a reduction of vascular NADPH oxidase and NF-κB activation. Endothelial dysfunction in diabetic animals was also associated to higher activities of the pro-inflammatory enzymes cyclooxygenase (COX) and the inducible isoform of nitric oxide synthase (iNOS), which were markedly reduced after anakinra treatment. Circulating IL-1β and TNF-α levels did not change in diabetic rats, but they were lowered by anakinra treatment.

Conclusions

In this short-term model of type 1 diabetes, endothelial dysfunction is associated to an IL-1 receptor-mediated activation of vascular NADPH oxidase and NF-κB, as well as to vascular inflammation. Moreover, endothelial dysfunction, vascular oxidative stress and inflammation were reduced after anakinra treatment. Whether this mechanism can be extrapolated to a chronic situation or whether it may apply to diabetic patients remain to be established. However, it may provide new insights to further investigate the therapeutic use of IL-1 receptor antagonists to obtain vascular benefits in patients with diabetes mellitus and/or atherosclerosis.

Abstract 560: Inflammation Converts Glucose Into A Deleterious Agent In Human Aortic Smooth Muscle Cells

Although hyperglycemia is an independent risk factor for vascular diseases, the links between glucose metabolism and atherosclerosis still require elucidation. We have previously shown that vascular cells, which regulates the glucose entry, are not damaged by high glucose concentrations unless they are primed with an inflammatory stimulus like interleukin (IL)1β. We now analyze the mechanisms accounting for the synergism between high glucose and IL1β. Under high glucose conditions (22 mmol/L), cultured human aortic smooth muscle cells (HASMC) exhibited excess glucose uptake and consumption (from 4.2±0.6 to 7.5±0.7 pmol per cell/24 h) associated to increased GLUT1 transporters expression only when co-stimulated with 10 ng/mL IL1β. However, the simple excess entry of glucose was not deleterious in these cells, as the inhibition of mitochondrial respiration with 0.5 mmol/L sodium azide increased glucose uptake and consumption (from 6.0±0.1 to 13.2±0.8 pmol per cell/24 h) without triggering inflammatory responses, measured by NF-κB activation and iNOS expression. We found that, besides allowing glucose entry, IL1β enhances glucose-6-phosphate dehydrogenase (G6PD) expression by 3.6±1.0 fold and activates the pentose phosphate pathway (PPP) from 9.6±0.7 to 17.4±1.5 nmol/h.mg prot in HASMC submitted to high glucose, thus permitting some of the excess glucose to be metabolized by this route. This provides additional substrate for enhancing the NADPH oxidase enzymatic activity by from 472±30 to 785±41 RLUS/μg prot/min, producing superoxide anions that are required for the activation of NF-κB and iNOS. The higher the concentration of glucose the more the PPP pathway is activated, giving rise to an increased inflammatory condition which cannot be counterbalanced by the simultaneous regeneration of reduced glutathione. We conclude that IL1β transforms excess glucose into a deleterious agent in HASMC by increasing glucose uptake, which is diverted into the PPP, promoting the pro-oxidant conditions required for the exaggeration of inflammatory pathways. Interestingly, all these pathways were blocked with the IL1 receptor antagonist anakinra (1 μmol/L), suggesting this anti-inflammatory drug can be effective for preventing diabetic vasculopathy.

Osteonecrosis of the jaw as an adverse bisphosphonate event: three cases of bone metastatic prostate cancer patients treated with zoledronic acid

Bisphosphonates offer a significant improvement in the quality of life for cancer patients; these potent inhibitors of bone resorption have been shown to markedly reduce the morbidity frequently resulting from bone metastases. Despite the success of bisphosphonates as therapeutic agents, however, toxicity in the form of osteonecrosis of the jaw (ONJ) is a rare complication whose incidence rate has climbed in recent years. ONJ is defined as an unexpected development of necrotic bone in the oral cavity, and is commonly associated with administration of the bisphosphonates Pamidronate and Zoledronate. Clinical features include local pain, soft-tissue swelling, and/or loose teeth; ONJ is also often correlated with previous dental procedures, such as tooth extractions, during biphosphonate therapy. Although additional risk factors-such as corticosteroids, chemotherapy, radiotherapy, trauma or infection-exhibit etiological associations with ONJ, the real pathobiology has not yet been fully elucidated. Here we report our findings on all 2005 OJN cases presented at our institution resulting from bone metastatic prostate cancer treated with zoledronic acid. The incidence of ONJ is nearly 3% (3 out of 104) in these patients.

Circulating tumoral cells lack circadian-rhythm in hospitalized metastasic breast cancer patients

BACKGROUND

The relationship between breast cancer and circadian rhythm variation has been extensively studied. Increased breast tumorigenesis has been reported in melatonin-suppressed experimental models and in observational studies.

OBJECTIVES

Circulating Tumor Cells (CTC) circadian- rhythm may optimize the timing of therapies. This is a prospective experimental study to ascertain the day-time and night-time CTC levels in hospitalized metastasic breast cancer (MBC) patients.

MATERIAL AND METHODS

CTC are isolated and enumerated from a 08:00 AM and 08:00 PM blood collections. 23 MBC and 23 healthy volunteers entered the study. 69 samples were collected (23 samples at 08:00 AM and 23 samples at 08:00 PM from MBC; 23 samples from healthy volunteers). Results from two patients were rejected due to sample processing errors. No CTC were isolated from healthy-volunteers.

RESULTS AND DISCUSSION

No-differences between daytime and night-time CTC were observed. Therefore, we could not ascertain CTC circadian-rhythm in hospitalized metastasic breast cancer patients.

[Evaluation of the effect of Lactobacillus rhamnosus probiotic culture added to yogurt over Staphylococcus aureus, Escherichia coli O157:H7, Listeria monocytogenes and Salmonella enteritidis populations]

The effect of different types of probiotics present in yogurt over known populations of Staphylococcus aureus, Escherichia coli O157:H7, Listeria monocytogenes and Salmonella enteritidis was evaluated. The three types of yogurt used were: without added probiotics, with added probiotics (Lactobacillus casei CRL_431 and L. acidophilus CRL_730 CHR HANSEN) and another one with the same probiotics mentioned above and Lactobacillus rhamnosus (LR-35) culture. About 10(9) CFU/ mL of each potentially pathogenic bacteria was added to each type of yogurt tested, and kept in refrigeration at 4 degrees C during its shelf life, about 30 days. Bacterial count was done the initial day and every four days. Results obtained show that there is a difference in the inhibition between yogurts without added probiotics and the commercial yogurt with added probiotics; there is a clear inhibitory effect of the last one over S. aureus, E. coli O157:H7 and Listeria monocytogenes. The yogurt with added probiotics and L. rhamnosus did not show any additional inhibitory effect over the bacteria tested when compared with the yogurt with added probiotics. S. enteritidis could not be evaluated because it was not detectable in any yogurt samples evaluated four days after its inoculation. This study confirms the antagonic effect of probiotic cultures over potentially pathogenic bacteria for human beings and animals that may be present in food. Nevertheless, the use of L. rhamnosus did not produce any additional inhibitory effect.

Trastuzumab associated with successive cytotoxic therapies beyond disease progression in metastatic breast cancer

10617

Background: Whether trastuzumab should be continued after tumor progression remains unknown.We describe the activity of successive trastuzumab-containing regimens in patients with HER2-overexpressing metastatic breast cancer, as well as the response rate, time to progression and predictive factors for response. Methods: Descriptive retrospective study of trastuzumab activity in patients with HER2-overexpressing metastatic breast cancer treated at our hospital from 10/1999 to 07/2005. Results: 93 consecutive patients were evaluated obtaining an objective response rate (OR) for first-time administration of trastuzumab of 46.2%; stable disease (SD) 24.7%; clinical benefit (CB) 71%. Median time-to-progression (TTP) was 5 months (range: 1–39+). A total of 47 pts (50.5%) received a second trastuzumab-containing regimen with an OR of 29.8%; SD 21.3%; CB 51.1%; TTP 4 months (range: 1–31). A total of 21 pts (22.6%) received a third trastuzumab-containing regimen; OR 38.1%; SD 23.8%; CB 61.9%; TTP 4 months (range: 1–30+). A total of 10 pts (10.8%) received a fourth trastuzumab-containing regimen; OR 20%; SD 20%; CB 40%; TTP 4 months (range: 1–37). 5 pts (5.4%) received a fifth trastuzumab-containing regimen; OR 0%; SD 60%. Age < 45 years is a significant prognostic factor (p: 0.005, 95% CI, OR 5.6 (1.5–20.6)). A better response rate in the successive trastuzumab-containing regimens was observed, when there was a response in the first regimen: p = 0.04; 95% CI; OR 3.84 (1.07–14.65). With a follow-up of 16,5 months 45 pts (48,4%) are alive. Conclusions: Trastuzumab-containing therapies beyond disease progression in metastatic breast cancer show activity. There were more responses in younger pts. Those pts who had a previous response to trastuzumab therapy were more likely to respond to successive trastuzumab-containing regimens. Additional controlled studies are needed to test this approach.

No significant financial relationships to disclose.

Identification of the Copepod Intermediate Host of the Introduced Broad Fish Tapeworm, Diphyllobothrium latum, in Southern Chile

The broad fish tapeworm, Diphyllobothrium latum, is an exotic species in both Chile and Argentina, and until now, its copepod host has remained unknown in South American waters. The objective of this study was to identify calanoid copepod species that may be intermediate hosts for D. latum in Lake Panguipulli, Chile. In this lake, the highest levels of infection by this tapeworm occur in the introduced rainbow trout, Oncorhynchus mykiss. Of the 2 calanoid copepods found in Lake Panguipulli, Diaptomus diabolicus and Boeckella gracilipes, only D. diabolicus became infected on experimental exposure to coracidia. Prevalence (mean intensity) of experimental infection in adult copepods was 73.2% (2.8 procercoids per host). Diaptomus diabolicus has been demonstrated to be a new intermediate host; this is the first record of a copepod host for D. latum in South America.

Aislamiento de Escheríchia coli O157:H7 a partir de alimentos costarricenses

Cinco cepas de Escheríchia coli O157:H7 fueron aisladas a partir de muestras de alimentos en Costa Rica. Tres de ellas fueron aisladas a partir de visceras de pollo (3/150) y dos de leche cruda (2/150). Las muestras de visceras de pollo fueron adquiridas en supermercados detallistas ubicados en San José, y las muestras de leche cruda se obtuvieron de productores de leche del área Metropolitana de San José, Costa Rica. Este el es primer reporte del aislamiento de esta bacteria a partir de muestras de alimentos de Costa Rica y la región Mesoamericana.

Sexual behavior in sleep, sleepwalking and possible REM behavior disorder: a case report

Seven cases of sexual behavior during sleep (SBS) have been recently reported. The subjects had histories of behavioral parasomnias as well as positive family histories of parasomnia. A 27 year-old man with a history of sexual behavior during sleep was reported. His sleep history disclosed sleepwalking (SW) since 9 years of age. He also developed episodes of highly disruptive and violent nocturnal behavior with dream enactment at age 20 years, which often resulted in physical injuries either to himself or his wife and infant. His wife also reported episodes of amnestic sexual behavior that began 4 years before referral. During the episodes, the patient typically procured his wife, achieving complete sexual intercourse with total amnesia. Physical and neurological diagnostic workups were unremarkable. Family history disclosed sleepwalking in his brother. He was put on 2mg/day of bedtime clonazepam with a remarkable clinical improvement. This case involves either the combination of violent and non-violent sleepwalking with SBS, or the superimposition of presumed REM sleep behavior disorder (RBD) on top of preexisting SW in a man who also developed SBS in adulthood. Thus, this is a case report of probable parasomnia overlap syndrome.

Correlation between blood adenosine metabolism and sleep in humans

Blood adenosine metabolism, including metabolites and metabolizing enzymes, was studied during the sleep period in human volunteers. Searching for significant correlations among biochemical parameters found: adenosine with state 1 of slow-wave sleep (SWS); activity of 5'-nucleotidase with state 2 of SWS; inosine and AMP with state 3-4 of SWS; and activity of 5'-nucleotidase and lactate with REM sleep. The correlations were detected in all of the subjects that presented normal hypnograms, but not in those who had fragmented sleep the night of the experiment. The data demonstrate that it is possible to obtain information of complex brain operations such as sleep by measuring biochemical parameters in blood. The results strengthen the notion of a role played by adenosine, its metabolites and metabolizing enzymes, during each of the stages that constitute the sleep process in humans.

Rater agreement on interpersonal psychotherapy problem areas

There has been much outcome research on interpersonal psychotherapy (IPT) but little investigation of its components. This study assessed interrater reliability of IPT therapists in identifying interpersonal problem areas and treatment foci from audiotapes of initial treatment sessions. Three IPT research psychotherapists assessed up to 18 audiotapes of dysthymic patients, using the Interpersonal Problem Area Rating Scale. Cohen's kappa was used to examine concordance between raters. Kappas for presence or absence of each of the four IPT problem areas were 0.87 (grief), 0.58 (role dispute), 1.0 (role transition), and 0.48 (interpersonal deficits). Kappa for agreement on a clinical focus was 0.82. IPT therapists agreed closely in rating problem areas and potential treatment foci, providing empirical support for potential therapist consistency in this treatment approach.

Temporal variations of adenosine metabolism in human blood

Eight diurnally active (06:00-23:00 h) subjects were adapted for 2 days to the room conditions where the experiments were performed. Blood sampling for adenosine metabolites and metabolizing enzymes was done hourly during the activity span and every 30 min during sleep. The results showed that adenosine and its catabolites (inosine, hypoxanthine, and uric acid), adenosine synthesizing (S-adenosylhomocysteine hydrolase and 5'-nucleotidase), degrading (adenosine deaminase) and nucleotide-forming (adenosine kinase) enzymes as well as adenine nucleotides (AMP, ADP, and ATP) undergo statistically significant fluctuations (ANOVA) during the 24 h. However, energy charge was invariable. Glucose and lactate chronograms were determined as metabolic indicators. The same data analyzed by the chi-square periodogram and Fourier series indicated ultradian oscillatory periods for all the metabolites and enzymatic activities determined, and 24-h oscillatory components for inosine, hypoxanthine, adenine nucleotides, glucose, and the activities of SAH-hydrolase, 5'-nucleotidase, and adenosine kinase. The single cosinor method showed significant oscillatory components exclusively for lactate. As a whole, these results suggest that adenosine metabolism may play a role as a biological oscillator coordinating and/or modulating the energy homeostasis and physiological status of erythrocytes in vivo and could be an important factor in the distribution of purine rings for the rest of the organism.

A comparison of cardiopulmonary adaptations to exercise in pregnancy at sea level and altitude

OBJECTIVE

The purpose of this study was to compare maternal cardiopulmonary and fetal responses of lowlander pregnant women in the third trimester to exercise at sea level and at an altitude of 6000 feet.

STUDY DESIGN

Seven women at 33.86 +/- 1 weeks' gestation performed a symptom-limited maximal exercise test and a submaximal cardiac output exercise test at sea level at an altitude of 6000 feet. Cardiopulmonary and metabolic variables were measured and compared at sea level and altitude.

RESULTS

Maximal oxygen consumption and work levels were limited by short-term altitude exposure. Ventilatory variables were not significantly influenced by altitude exposure. During submaximal exercise no alteration in exercise efficiency or response was seen for most of the variables when altitude and sea level data were compared. Both cardiac output and stroke volume were elevated at altitude at rest but not during exercise, suggesting a lower reserve for both variables at altitude. Level of plasma glucose, lactate, norepinephrine, and epinephrine were not significantly influenced by altitude exposure. Fetal heart rate responses did not differ between the sea level and altitude conditions.

CONDITIONS

Lowlander pregnant women in the third trimester have some limitations to maximal aerobic capacity but not submaximal exercise on short-term altitude exposure. No ominous fetal responses have been observed during this study. The results suggest that pregnant women may engage in at least brief moderate exercise bouts at moderate altitude without adverse consequences.

Learning capability assessment and feature space optimization for higher-order neural networks

A technique for evaluating the learning capability and optimizing the feature space of a class of higher-order neural networks is presented. It is shown that supervised learning can be posed as an optimization problem in which inequality constraints are used to code the information contained in the training patterns and to specify the degree of accuracy expected from the neural network. The approach establishes: (a) whether the structure of the network can effectively learn the training patterns and, if it can, a connectivity which corresponds to satisfactorily learning; (b) those features which can be suppressed from the definition of the feature space without deteriorating performance; and (c) if the structure is not appropriate for learning the training patterns, the minimum set of patterns which cannot be learned. The technique is tested with two examples and results are discussed.

Long-term control of Chagas disease in Venezuela: effects on serologic findings, electrocardiographic abnormalities, and clinical outcome

To evaluate the long-term effects (20 years) of a Chagas control program (CCP) in Venezuela, a prospective serologic evaluation was carried out from 1981 to 1984 on 5771 inhabitants (8%) of Roscio county. This region was selected as a representative area where the national CCP was implemented effectively. Comparison with a serologic survey performed in the same region before the CCP disclosed a reduction in seropositive subjects from 47.8% to 17.1% (p less than .001), most marked amongst children and teenagers from 29.9% to 1.9%, suggesting that transmission of the disease had diminished. Similar seropositivity changes after the CCP were observed nationwide. Because decreased superinfection would also be expected to occur, we tried to ascertain whether the clinical outcome of seropositive individuals living in Roscio county had improved. The mean age of seropositive subjects between both surveys increased significantly from 34.9 +/- 17.3 to 46.7 +/- 15.1 years (p less than .001). Additionally, we examined clinically and obtained electrocardiograms from 775 seropositive subjects. They were classified as asymptomatic (group A, n = 614) or as symptomatic, having mild-to-moderate heart symptoms (group B, n = 99) or having advanced congestive heart failure (group C, n = 62). Their electrocardiograms were compared with those of 923 seronegative subjects collected simultaneously and with published data obtained before the CCP. Comparison of the age-related rates of electrocardiographic abnormalities of seropositive individuals before and after the CCP showed that they did not differ significantly by linear regression analysis, by the Kruskal-Wallis test, or by the normal approximation to the binomial distribution.(ABSTRACT TRUNCATED AT 250 WORDS)