Air change rates and infection risk in school environments: Monitoring naturally ventilated classrooms in a northern Italian urban context

The importance of building ventilation in avoiding long-distance airborne transmission has been highlighted with the advent of the COVID-19 pandemics. Among others, school environments, in particular classrooms, present criticalities in the implementation of ventilation strategies and their impact on indoor air quality and risk of contagion. In this work, three naturally ventilated school buildings located in northern Italy have undergone monitoring at the end of the heating season. Environmental parameters, such as CO2 concentration and indoor/outdoor air temperature, have been recorded together with the window opening configurations to develop a two-fold analysis: i) the estimation of real air change rates through the transient mass balance equation method, and ii) the individual infection risk via the Wells-Riley equation. A strong statistical correlation has been found between the air change rates and the windows opening configuration by means of a window-to-volume ratio between the total opening area and the volume of the classroom, which has been used to estimate the individual infection risk. Results show that the European Standard recommendation for air renewal could be achieved by a window opening area of at least 1.5 m2, in the most prevailing Italian classrooms. Furthermore, scenarios in which the infector agent is a teacher show higher individual infection risk than those in which the infector is a student. In addition, the outcomes serve school staff as a reference to ensure adequate ventilation in classrooms and keep the risk of infection under control based on the number of the students and the volume of the classroom.

Ventilation strategies to reduce airborne transmission of viruses in classrooms: A systematic review of scientific literature

The recent pandemic due to SARS-CoV-2 has brought to light the need for strategies to mitigate contagion between human beings. Apart from hygiene measures and social distancing, air ventilation highly prevents airborne transmission within enclosed spaces. Among others, educational environments become critical in strategic planning to control the spread of pathogens and viruses amongst the population, mainly in cold conditions. In the event of a virus outbreak - such as COVID or influenza - many school classrooms still lack the means to guarantee secure and healthy environments. The present review examines school contexts that implement air ventilation strategies to reduce the risk of contagion between students. The analysed articles present past experiences that use either natural or mechanical systems assessed through mathematical models, numerical models, or full-scale experiments. For naturally ventilated classrooms, the studies highlight the importance of the architectural design of educational spaces and propose strategies for aeration control such as CO₂-based control and risk-infection control. When it comes to implementing mechanical ventilation in classrooms, different systems with different airflow patterns are assessed based on their ability to remove airborne pathogens considering parameters like the age of air and the generation of airflow streamlines. Moreover, studies report that programmed mechanical ventilation systems can reduce risk-infection during pandemic events. In addition to providing a systematic picture of scientific studies in the field, the findings of this review can be a valuable reference for school administrators and policymakers to implement the best strategies in their classroom settings towards reducing infection risks.

Spirocercosis in red fox (Vulpes vulpes) in a natural reserve located in a meso-Mediterranean area

Spirocerca lupi Rudolphi 1809 (Nematoda Spirocercidae) has an indirect cycle involving intermediate and paratenic hosts, having domestic or wild canids as the main definitive hosts. The most frequent pathology affecting dogs is a granulomatous tumor-like growth containing adults in the oesophagus and aorta. There are very few references about the presence of nodules in the stomach. There is scant information about the epidemiology of this disease in wild red foxes in meso-Mediterranean areas. In this work we report on the natural infection of wild red foxes by Spirocerca lupi and the damage produced in the stomach wall in an area where contact with other potential definitive hosts (canids) is very rare. From July 2015 to November 2016, 61 red foxes were sampled. 18.03% of the stomach walls examined had nodules containing Spirocerca lupi adults and eggs. The prevalence of infection was similar for young and adult groups (23.81 and 18.18%; χ2 = 0.25; df = 1; P = 0.6171) and it was higher in females than in males (25.81 versus 10.00%, χ² = 2.58; df = 1; P = 0.1082). The red fox population in the area seems to be well established judging from their age distribution and the fact that they could be captured all year round. It would appear that in the absence of other main definitive host S. lupi population is able to survive just parasitizing red foxes. Pathologic effects of this parasite on red foxes seems to show some differences related to domestic dogs. These results also indicates as predator control programs can maintain suitable host populations with reduced level of infection.

Dose Modification in Biologic Therapy for Moderate to Severe Psoriasis: A Descriptive Analysis in a Clinical Practice Setting

INTRODUCTION

In biologic therapy, dose modification in carefully selected patients when psoriasis is in remission could reduce treatment costs and the risks associated with drug exposure.

MATERIAL AND METHODS

Observational, descriptive, crosssectional study, performed in January 2014, of 112 patients with moderate to severe psoriasis who had been on biologic therapy for at least 6 months. The therapeutic objective in all cases was to achieve and maintain a 75% reduction in Psoriasis Area and Severity Index (PASI 75). All the patients had started treatment with the standard regimen. During treatment, the dose had been reduced in patients who achieved the therapeutic objective and escalated in those who failed to respond adequately to standard doses.

RESULTS

At the time of the study, 42.9% of the patients were receiving the standard dose, 50% were on a reduced dose, and 7.1% were on an escalated regimen. The agent with which the dose was most often reduced was adalimumab (57.7%), and the agents with which therapy was most often escalated were ustekinumab (17.9%) and infliximab (12.5%). Patients who received reduced doses had significantly longer-standing disease (P=.049) and longer treatment duration with the same biologic agent (P=.009). In the group that did not fulfill the criteria for dose reduction, the proportion of patients with psoriatic arthritis was significantly higher (P=.023). Cost savings were as follows: 21.5% with adalimumab, 13.8% with etanercept, .9% with ustekinumab, and .55% with infliximab.

CONCLUSIONS

Patients with longer-standing disease and longer treatment duration with the same biologic agent were significantly more likely to be candidates for dose reduction. The proportion of patients with psoriatic arthritis was greater in the group of patients who did not fulfill the conditions for dose reduction. The overall cost saving achieved using the dose modification algorithm described in this study was 13%. Controlled studies are needed to define the profile of the patients best suited for dose reduction strategies without loss of treatment efficacy.

[Infection by human papilloma virus amongst female inmates in a social re-adaptation centre in South-West Mexico]

INTRODUCTION

The aim of this work is describe the epidemiology of HVP amongst female inmates.

MATERIAL AND METHODS

A total of 82 women were studied in a cross sectional study. Epidemiological data were collected through a direct interview. Samples of cervical cells were taken. HPV and genotypes were identified by molecular test.

RESULTS

Global HPV prevalence was 20.7%. Fifteen different genotypes were identified 60% low risk HPV, 26.7% high risk HPV and 13.3% were not classified in any of the two groups. Types 6/11 were the most common. 23.5% (04/17) of HPV positives samples had multiple infections, 3 with 2 genotypes and one with 3. Association between infection with HPV and smoking was found, p= 0.0258, OR 3.79 IC 95% (1.01-15.58).

[Immunological characteristics of limbal epithelial cells: in vitro analysis of TLR4 function]

OBJECTIVE

The aim of the present study was to determine the expression of TLR4 on human limbal epithelial cells cultivated in vitro, and to determine its cellular function after stimulation with lipopolysaccharide (LPS).

METHODS

Limbal epithelial cells were isolated from sclera-corneal rims and stimulated for 24 hours with different doses of LPS from E. coli and from Pseudomonas. After stimulation, the cells were harvested, stained with antibodies against human TLR4 and analysed by flow cytometry. mRNA was obtained and RT-PCR was performed for the identification of TLR4. Secretion of TNF-alpha by these cells was evaluated by ELISA of the supernatant.

RESULTS

Limbal epithelial cells expanded in vitro constitutively expressed the TLR4 molecule. After stimulation of cells with LPS the average fluorescence intensity increased, indicating that the expression of extracellular TLR4 was augmented. The expression of TLR4 mRNA was also increased with LPS stimulation, with maximum expression measured at 10 ng/ml LPS. The level of TNF-alpha in the supernatant was not different between the stimulated and the non-stimulated cells.

CONCLUSIONS

Although stimulation of in vitro limbal epithelial cells with LPS up-regulates the extracellular expression of TLR4, the function of TLR4 does not seem to be associated with the secretion of TNF-alpha by these cells. These results are consistent with the proposal that the corneal epithelium is an immunosilent site in the eye.

[Expression of B7 molecules and TLR-9 on corneal epithelial cells infected with adenovirus: clinico-pathological implications in viral keratoconjunctivitis]

PURPOSE

B7 molecules are a family of proteins that co-stimulate T cells during immune activation. Normally the corneal epithelial cells (CEC) do not express these molecules on their cell surface. Toll-like receptors play an important role in the innate immune response to invading pathogens and recently have been demonstrated to be expressed on mice cornea. The objective of this study was to determine whether adenoviral infection induces B7 molecules and TLR9 on human CEC.

METHODS

CEC were isolated from human corneas treated with dispase-II, and grown in the presence of supplemented hormonal epithelial medium until confluence. Then CEC were then infected with adenovirus 5 (Ad5) and cultured for different times. The CEC were then recovered and stained against human CD80, CD86, TLR-9 and cytokeratin. All cells were analyzed by flow cytometry.

RESULTS

Ad5 infection of CEC induced the expression of B7 molecules and TLR-9 after 24 hours in culture, rising to maximum levels at 72 hours. B7 expression at 72 hours was as follows: CD80 expression on infected CEC was 62% (standard error [SE] 2.6) versus 3% (SE 1.2) on non-infected CEC (p<0.001); CD86 expression on infected CEC was 95% (SE 2.1) versus 5% (SE 1.2) on non-infected CEC (p<0.001). TLR-9 expression at 72 hours was 80% (SE 1.2) on infected CEC versus 5% (SE 1) on non-infected CEC (p<0.001).

CONCLUSIONS

Ad5 infection induced the expression of B7 molecules and TLR-9 on CEC.

[Erythrodermic lichen planus pemphigoides]

Lichen planus pemphigoides is a clinico-histological subtype of lichen planus in which there are bullous lesions similar to those of bullous pemphigoid. Lichen planus is included among the rare causes of erythroderma. We present a case of erythrodermic lichen planus pemphigoides in a 49-year-old female patient who satisfactorily responded to treatment with cyclosporine. A detailed physical examination and immunofluorescence study are key to the diagnosis of lichen planus pemphigoides.

Burow's grafts in the facial region

BACKGROUND

Full-thickness skin grafts are an important tissue source for reconstructive surgery. Burow's grafts are full-thickness skin grafts that use adjacent lax skin as the donor site. This technique has also been referred to as island grafts, dog-ear grafts or adjacent-tissue skin grafts.

OBJECTIVE

The objective was to describe the technique of Burow's grafts for reconstruction of facial defects taking account of its benefits and limitations.

METHODS

The operative technique is simple: after a circular excision of the cutaneous lesion, we enlarged the excision line (towards one or both sides of the defect) following the relaxed tension lines. We created a secondary triangular defect by excising skin that is then used for the graft (as donor site). After adequate undermining, we proceeded to direct linear closure of this secondary defect. Finally, the graft was placed and sutured in the remaining defect.

RESULTS

The proximity of the donor site provides an excellent tissue match because colour, hair density, texture, sebaceous features and thickness are similar to the recipient site. A good cosmetic result is therefore ensured.

CONCLUSION

Burow's grafts can be a good choice for reconstruction of extensive facial surgical defects because of aesthetic results. In addition, it is a simple technique that can be performed in one sole surgical act, with local anaesthesia and without changing the operative site.

Epidermolysis bullosa acquisita: diagnosis by fluorescence overlay antigen mapping and clinical response to high-dose intravenous immunoglobulin

Epidermolysis bullosa acquisita (EBA) is a chronic, subepidermal blistering disease characterized by the presence of autoantibodies to type VII collagen, located below the lamina densa of the basement membrane zone (BMZ). There is a large clinical and histological overlap between EBA and other subepidermal autoimmune bullous diseases, therefore, complex immunological techniques are required to make an accurate diagnosis. Therapy of EBA is also a difficult issue. Most patients do not respond to several common immunosuppressive agents. We describe a patient who has shown a good response to high-dose intravenous immunoglobulin therapy.

Nuclear bodies domain changes with microspore reprogramming to embryogenesis

We analysed the presence of nuclear bodies and particularly Cajal bodies during representative stages of gametophytic and haploid embryogenic development in isolated microspore and anther cultures of a model system (Brassica napus cv. Topas) and a recalcitrant species (Capsicum annuum L. var. Yolo Wonder B). The nuclear bodies domain is involved on several important roles on nuclear metabolism, and Cajal bodies are specifically involved on the storage and maturation of both snRNPs and snoRNPs, as well as other splicing factors, necessary for mRNA and pre-rRNA processing, but not directly on the transcription. In this study, immunofluorescence and immunogold labelling with anti-trimethylguanosine antibodies against the specific cap of snRNAs, ultrastructural and cytochemical analysis were performed on cryoprocessed samples at confocal and electron microscopy respectively. Results showed that Cajal bodies increase during the early stages of microspore embryogenic development (young pro-embryos), compared to microspore and pollen development. Our results suggest that Cajal bodies may have a role in the transcriptionally active, proliferative stages that characterise early microspore embryogenic development.

Acrokeratosis paraneoplastica (Bazex syndrome)

Bazex syndrome is a paraneoplastic dermatosis characterized by acral psoriasiform lesions associated with an underlying neoplasm. We present the case of a 64-year-old patient that was diagnosed with squamous cell lung carcinoma after being evaluated for lesions compatible with paraneoplastic acrokeratosis. With a high frequency Bazex syndrome is the earliest marker of an underlying subclinical neoplasm. An early suspicion is of the outmost importance in order to perform a prompt diagnosis of an underlying malignancy. We propose a diagnostic algorithm upon suspicion of acrokeratosis paraneoplastica and review the pathogenesis of this entity.

[Tetracaine-induced systemic contact-type dermatitis]

We report the case of a 71-year-old-man with dermatitis in the groin area. Forty-eight hours previously, he had undergone transurethral resection for benign prostatic hyperplasia. During the prostatectomy, the probe was lubricated with a urological ointment containing the topical anesthetic, tetracaine. The patient had previously experienced severe pruritus and fissures in the perianal area after using antihemorrhoidal ointments. Biopsy and patch testing with the standard series and lubricant ointment showed positive reactions to this lubricant, called "urological lubricant" (UL) (+ + +) with caine mix (+ + +). The patient was diagnosed with systemic contact-type dermatitis due to caine mix. The dermatitis improved with topical steroids and oral antihistamine agents.

Histopathologic and histochemical characterization of calcified structures in hamsters inoculated with Paracoccidioides brasiliensis

In pathogenicity studies of 31 Paracoccidioides brasiliensis isolates preserved using Castellani's method we intraperitoneally inoculated 104 young adult hamsters and found laminated concentric structures and calcified appearance that resembled Schaumann bodies, in 43 of them, especially in animals with apparently good condition. We characterized these structures histologically and histochemically using different stains (PAS, Grocott, haematoxylin-eosin, Von Kossa). The Von Kossa staining revealed calcium in these structures. Similar structures have been described in patients with sarcoidosis and also in hamsters inoculated with P. brasiliensis. We found no correlation between the presence of these calcifications and serum calcium levels.

[Pseudoathetosis after medullar and pontine hemorrhage]

INTRODUCTION

Athetosis is a slow and purposeless involuntary movement which changes in frequency, severity. The term pseudoathetosis is used when this movement is associated with proprioceptive sensory impairment.

CLINICAL CASE

A 63 year old man developed right medulla and pons hemorrhage and presented loss of proprioception in left hemibody and athetosis movements in left hand.

CONCLUSION

We report a case of pseudoathetosis associated with loss of proprioceptive sensation.

Diabetes education in the elderly: a 5-year follow-up of an interactive approach

A continuing interactive educational model was established for elderly patients with diabetes mellitus. The effects were studied in 148 diabetic patients aged > or = 60 years who participated in 60 monthly scheduled interactive meetings over a 5-year period. The meetings were performed as group discussions, cultural activities, dining out, and the like. Empowering patients with skills, perceptions and feelings to cope with diabetes and metabolic control was emphasized, rather than clinical aspects. Comparison between pre-programme and 5 years later demonstrates a significant increase (P, 0.001) of knowledge and skills to deal with treatment requirements, and a reduction in body weight and antidiabetic medication (daily doses of insulin and oral compounds; P < 0.01 and P < 0.05, respectively). HbA1c levels improved significantly (P < 0.02). There were less diabetes related conditions requiring emergency services and hospital admission.

The costs and effectiveness of three vitamin A interventions in Guatemala

The purpose of the study presented in this paper was to estimate, using secondary sources of data, the cost and effectiveness of three programs to combat vitamin A deficiency in Guatemala-the national sugar fortification program, a targeted capsules distribution program and the promotion of home food production combined with nutrition education and to draw conclusions concerning priorities for Guatemala. Data on the costs and coverage were collected from implementing agencies in Guatemala. Coverage data were converted into a common set of impact indicators. Sensitivity analyses were conducted on variables whose precise value was uncertain. Potential impacts of improvements in program performance operations were also explored. The analysis found the cost per high-risk person achieving adequate vitamin A to be US $0.98 for fortification, US $1.68-1.86 for capsule distribution and US $3.10-4.16 for food production/education. Fortification is the most efficient option if vitamin A levels in sugar are maintained at reasonable levels. Where fortified sugar is not consumed and vitamin A deficiency is highly prevalent, small-scale, targeted, complementary interventions such as capsules and food production education may be appropriate for sustained broader impacts.

Multiple hidrocystomas

Apocrine hidrocystoma is a cyst from the secretory portion of the apocrine sweat gland and tends to occur as a solitary facial lesion. We report a 66-year-old woman with multiple, cystic lesions on her face. Histopathology revealed cystic spaces lined by a row of secretory cells showing decapitation secretion. We emphasize the multiple character of the case and discuss its distinction from so-called eccrine hidrocystomas.

[Acute non-calculous cholecystitis in non-hospitalized patients]

The increase of acute acalculous cholecystitis (AAC) in out-patients produces the review of clinic files of 810 cases of cholecystectomy because of acute cholecystitis; 27 were acalculous (3.3%). AAC was predominant in female sex (20/27) in which the mean age was 37 years. In twelve patients (44%) the cholecystitis was associated with diabetes and hypertension. The clinical manifestations were similar to patients with cholelithiasis and preoperative diagnosis was made in only 33% by ultrasonography. The surgical findings were: Edematous gallbladder without stones, wall thickness and necrosis, as well as perivesicular adherences. In all patients the treatment was immediate cholecystectomy, with morbidity of 14.4% and no mortality. AAC is not only present in critically ill patients, but also is present in patients not hospitalized, and immediate cholecystectomy is the treatment of choice.

Root exuded nod-gene inducing signals limit the nodulation capacity of different alfalfa varieties with Rhizobium meliloti

Different nodulation capacities were found among nine different varieties of alfalfa, cultivated in the Central region of Mexico, by Rhizobium meliloti 2011. A correlation between nodulation capacity and foliar dry weight was observed, which points to a genotype dependance on these parameters. A correlation between the nodulation capacity and the R. meliloti nod-gene inducing activity of the root exudates from the different varieties, as measured by β-galactosidase induction in a test system consisting of a R. meliloti nodC-lacZ strain incubated with each root exudate, was established. When the root exudate from the best nodulating variety was added to the four poorest nodulating varieties, an increase in nodule formation was observed. We conclude that root exuded nod-gene inducing signals are a symbiotically-limiting component in natural populations of the poorest nodulating varieties of alfalfa.

Patterns in sun exposure and sunscreen use among Puertorrican adolescents

A survey of 245 adolescents visiting different San Juan area beaches was conducted to determine the frequency with which they used sunscreens lotions. Seventy-two percent of the teenager in the survey stated that they spent most weekends in the sun; however, only 68% always used sunscreen, while 31% never did. Prevalence factors found to be associated with the sunscreen use included male sex (odd ratio = 1.01 P < 0.01), having a friend who routinely used the lotion (odds ratio = 0.06, P < 0.05), and having parents who strongly recommend the sunscreen use, (odds ratio = o.g, P > 0.05). This survey substantiates poor compliance with sunscreen lotion use by teenagers despite increasing evidence of the dangers of sun exposure.

[Levels of L-carnitine in the Venezuelan infant population]

The L-carnitine blood serum and amniotic fluid levels were measured in 133 samples obtained from clinically healthy patients: 39 pregnant women with a fetal gestational age ranging from 14 to 40 weeks, 13 newborn children less than a day old, 19 newborn children between the ages of 1 and 30 days, 8 breast-feed babies and 19 children over two years of age. No significant statistical differences were seen in the maternal blood serum and amniotic fluid samples for the different gestational ages considered in the study. The average values were found to be 22.6 +/- 5.1 nmol/mL for maternal blood serum and 25.3 +/- 9.4 nmol/mL for amniotic fluid. The blood serum levels were found to be greater in the group between the ages of 1 to 30 days, reaching levels of 43.1 +/- 7.4 nmol/mL. In the group aged 1 month-18 years, the serum levels were on the average 34.3 +/- 6.7 nmol/mL. The variations found among these groups reflect characteristics specific of our population. These values should be further researched since they differ from those values reported by the Anglo-Saxons. L-carnitine concentration; blood serum level; amniotic fluid level.

[Spermatogonia types in tepezcuintle (Cuniculus paca). Ultrastructural study]

Ultrastructural studies of different types of spermatogonia by thin section techniques and transmission electron microscopy showed that Cuniculus paca has two types of Type A spermatogonia (A-O and A-1). Samples were taken at different stages of the cycle in the seminiferous tubule epithelium presented a similar pattern as those of other rodents. Type B spermatogonia are similar to those of the rat, the difference being that the heterochromatic zones are larger and more numerous. Both characteristics differentiate them from preleptotenic spermatocytes.

Semen analyses in adolescent diabetic patients

We studied the semen quality and plasma testosterone levels (T) in 32 adolescent patients with insulin-dependent diabetes mellitus and in an aged-matched control group. Semen volume, motility and morphology were significantly lower in diabetics whereas seminal fructose and glucose were significantly higher. Even though the sperm count was lower in these adolescent diabetics, the difference was not significant when compared to the control group. No difference was observed in plasma testosterone levels. Patients were divided into two groups according to the presence of retinopathy and neuropathy, and degree of metabolic control. Spermiogram parameters, seminal fructose and glucose were lower in diabetics with neuropathy. No difference was observed in spermiogram parameters between diabetic patients with or without retinopathy, but seminal fructose, and glucose were lower in the former. All spermiogram parameters, as well as seminal fructose were lower in diabetics with poor metabolic control but seminal glucose was higher. No correlation was detected between clinical parameters (age at onset and duration of diabetes mellitus and time since first ejaculation), semen parameters, plasma T, glycemia and glycosuria. In conclusion, a deterioration of the quality of human semen occurs in adolescent diabetic patients. Neuropathy and poor metabolic control seem to be important factors of this deterioration. The presence of retinopathy does not correlate with T and semen quality.

[Persistent iridoplegia and filamentary keratitis complications following cataract extraction (author's transl)]

In a series of 3,222 cataract operations where enzymatic zonulolysis with Alphachymotrypsin was employed, the authors describe two complications which are thought to be due to the effects of the enzyme. They are the persistent iridoplegia in 18 cases (0.05) and the filamentary keratitis in 34 patients (1.05%). The clinical picture of an acute enzymatic intraocular pressure increase and the appearance of a persistent iridoplegia are discussed. Furthermore, these complications are brought together in tables and associated with other which are also thought to be caused by Chymotrypsin.

[Contributions to the surgical technique of external dacryocystorhinostomy (author's transl)]

The authors describe some modifications of the surgical technique of external dacryocystorhinostomy. The preliminary exploration methods and their evaluation are considered. An arched skin incision is used for a more anatomical dissection to approach the lacrimal sac. The following bone trepanation is then made with burrs designed by Burch Barraquer. It should be rather large (15-20 mm), backwards and downwards in the nose bone. A running suture, with three external skin stiches as pexia, is used to tie the anterior muco-mucosal flaps together. This suture is them removed after approximately 12 days. Management and procedures in special cases as well as in reoperations are also discussed.?Author

Effect of Peruvosid (CD412) on excitability and functional refractory period of atrial and ventricular tissues in cardiomyopathy caused by Trypanosoma cruzi

Attempts were made to produce myocarditis by Trypanosoma cruzi inoculation in healthy dog puppies 6 to 8 weeks old. Significant electrocardiographic abnormalities were produced, coinciding with interstitial inflammatory processes in the cardiac tissue and with degenerative changes in the myocardial fibres. In puppies showing these changes, profound changes in the excitability and the functional refractory period of the atrial and ventricular muscular tissue were observed. The administration of Peruvosid in doses of 0.0240 to 0.0647 mg./kg. tended to diminish the excitability, previously increased by the inflammatory process, at the same time increasing the functional refractory period duration which had previously been shortened. The fact that Peruvosid corrects these fundamental factors in the genesis of cardiac arrhythmias suggests that the drug may be useful in the treatment of cardiac insufficiency produced by Chagas' myocardiopathy, in which arrhythmias are one of the basic characteristics.