Efficacy and cost effectiveness of rapid on site examination (ROSE) in management of patients with mediastinal lymphadenopathies.

BACKGROUND: The diagnostic and staging approach for the mediastinal lymphadenopathies, with or whithout pulmonary lesions endoscopically visible, is based on transbronchial needle aspiration (TBNA) during fiberoptic bronchoscopy and on mediastinoscopy. One important factor impacting on TBNA sensitivity is the rapid on site cytological examination (ROSE). AIM: The aim of this study was to evaluate the economic impact of TBNA and TBNA + ROSE, in the diagnosis of these lesions. PATIENTS AND METHODS: 120 patients, affected by mediastinal lymphadenopathies suspected for lung cancer, underwent TBNA during fiberoptic bronchoscopy: 60 patients without ROSE (group A) and other 60 with ROSE (group B). Whenever needle aspirations failed to provide diagnosis, the patient underwent mediastinoscopy. The economic impact of the diagnostic process was performed. RESULTS: In group A, 39 patients (65%) obtained a diagnosis with TBNA while 21 patients (35%) required mediastinoscopy. In group B, 48 patients (80%) obtained a diagnosis with TBNA + ROSE, while 12 patients (20%) required mediastinoscopy. With regards to the costs of the procedures performed in the diagnostic process, the use of TBNA with ROSE as first diagnostic approach has saved a considerable amount of euros (19,413) compared to the use of TBNA without ROSE and the combined procedure increased (p < 0.02; chi square test) the sensitivity of TBNA by 15%. CONCLUSIONS: ROSE significantly impacts on the diagnostic yield, as well as on the overall management costs of patients with mediastinal lymphadenopathy, suspected for lung cancer.

[Detection, characterization and clinical significance of circulating cancer cells in patients surgically treated for breast cancer]. / Ricerca, caratterizzazione e significato clinico di cellule tumorali circolanti in pazienti operate per cancro della mammella.

Recent technological advances have led to an increasing ability to detect isolated or groups of tumour cells in blood, lymph nodes or bone marrow in patients with different tumour types. However, the clinical evidence of these advances is unclear. The detection and the characterisation of circulating breast cancer cells and the eventually micrometastasis represent an important prognostic factor with therapeutic implications. The number of neoplastic cells being very small, these are not easily detected by using only cytomorphology, possibly associated to immunocytochemistry. In the last decade many studies have been directed in order to identify new assays. In the present review the Authors summarize advantages and disadvantages about two different technical approaches: molecular and immunomagnetic selection with cellular enrichment and immunocytochemistry.

Immediate skin reactivity to histamine and to allergens in cohorts of 9-year-old schoolchildren studied 16 years apart.

BACKGROUND: Differing or increasing prevalence of positive allergen skin-prick tests observed in Europe could at least in part be explained by population changes in histamine skin reactivity. These changes would also alter the relationship between positive allergen skin-prick tests and serum IgE. OBJECTIVE: To assess changes in histamine reactivity, allergen skin-prick tests and serum IgE in our geographical setting. METHODS: We compared the outcome of two epidemiological surveys conducted 16 years apart in unselected 9-year-old schoolchildren (170 in 1983 and 176 in 1999) from a semi-rural region in central Italy. Outcome measures were skin-prick tests with two histamine concentrations (10 and 1 mg/mL) and 11 locally relevant allergens; serum total and specific IgE for positive allergens. RESULTS: The two histamine concentrations induced significantly larger mean weal diameters in 1999 than in 1983 (10 mg/mL: 5.28+/-0.82 mm vs. 3.25+/-0.97 mm; P<0.001). Whereas the prevalence of subjects with at least one positive allergen-induced weal reaction (>or=3 mm) increased over the 16 years (from 15.3% in 1983 to 25.6% in 1999), the prevalence of positive skin-prick tests, expressed as the allergen/ histamine weal ratio, remained almost unchanged. A given allergen weal diameter yielded less total (P<0.05 by Student's t-test for cumulative weals <8 mm) and specific (P<0.01 by Student's t-test for weals <3 mm, P<0.05 by Kruskal-Wallis test) serum IgE in 1999 than in 1983. CONCLUSIONS: Although the causes and mechanisms remain unclear, the increased histamine skin reactivity over time is associated with an increase in positive allergen skin-prick tests. In the presence of increased tissue and organ susceptibility to histamine, minute amounts of specific IgE could have important biological consequences.

Exhaled nitric oxide in asthmatic and non-asthmatic children: influence of type of allergen sensitization and exposure to tobacco smoke.

Asthmatic bronchial inflammation is associated with increased nitric oxide concentrations in exhaled air (eNO). Recent data suggest that this effect arises from atopy. Our aim in this study was to find out whether atopy and sensitization to particular allergens influences eNO levels. A total of 213 subjects (41 asthmatics and 172 controls) (96 boys and 117 girls, 7.3-14 years of age) were studied. Parents completed a questionnaire that sought information on their children's respiratory symptoms and exposure to tobacco smoke. Subjects underwent skin-prick tests for the following common allergens: Dermatophagoides pteronyssinus (Dpt), cat fur, Aspergillus fumigatus, Alternaria tenuis, mixed grass, mixed tree pollen, Parietaria officinalis, egg, and cow's milk. eNO was collected in 1-l mylar bags (exhaled pressure 10 cmH2O, flow 58 ml/s) and analyzed by using chemiluminescence. Atopic and non-atopic children without a history of chronic respiratory symptoms had a similar geometric mean eNO (atopics, n = 28, 11.2 p.p.b.; non-atopics, n = 96, 10.0 p.p.b.; mean ratio 1.1, 95% confidence interval [CI]: 0.7-1.6). Conversely, atopic asthmatic subjects had significantly higher eNO values than non-atopic asthmatic subjects (atopics, n = 25, 24.8 p.p.b.; non-atopics, n = 16, 11.4 p.p.b.; mean ratio 2.2, 95% CI: 1.2-3.9, p= 0.000). In children with rhinitis alone (n = 15) and those with lower respiratory symptoms other than asthma (n = 33), eNO increased slightly, but not significantly, with atopy. eNO levels correlated significantly with Dpt wheal size (r = 0.51) as well with the wheal size for cat, mixed grass, and Parietaria officinalis (r = 0.30-0.29), and with the sum of all wheals (r = 0.47) (p= 0.000). Subjects sensitized only for Dpt (but not those subjects sensitized only for grass pollen or other allergens) showed significantly higher eNO levels than non-atopic subjects (16.4 p.p.b. vs. 10.2 p.p.b., mean ratio 1.6, 95% CI: 1.1-2.3, p= 0.002). In asthmatic subjects, Dpt sensitization markedly increased eNO levels (Dpt-sensitized subjects: 28.0 p.p.b.; Dpt-unsensitized subjects: 12.2 p.p.b.; mean ratio 2.3, 95% CI: 1.5-3.5, p= 0.000). Non-asthmatic Dpt-sensitized subjects also had significantly higher eNO values than non-asthmatic, non-Dpt-sensitized subjects (14.2 p.p.b. vs. 10.1 p.p.b.; mean ratio 1.4, 95% CI: 1.1-1.9, p= 0.008). No difference was found between eNO levels in asthmatic subjects and control subjects exposed or unexposed to tobacco smoke. In conclusion, eNO concentrations are high in atopic asthmatic children and particularly high in atopic asthmatics who are sensitized to house-dust mite allergen.

Is the increase in childhood asthma coming to an end? Findings from three surveys of schoolchildren in Rome, Italy.

Time trends in the prevalence of asthma, family history of asthma and atopy in Roman schoolchildren were assessed. The study population consisted of all children (aged 6-14 yrs) attending two primary schools in Rome, situated in urban areas that differed markedly in socioeconomic conditions and environmental pollution. Three questionnaire-based surveys were conducted in 1974, 1992 and 1998 in 2,259, 1,229 and 1,139 children. The prevalence of asthma in males and females increased significantly during 1974-1992 and remained stable from 1992-1998. In age groups born in the subsequent 4-yr periods it increased almost linearly, for children born from 1962-1965 to 1982-1985 (4.4%-12.5%), and remained remarkably stable in children born after 1985. Because the prevalence of asthma had a steeper trend in males than in females (approximately 0.55% x yr(-1) versus 0.25% x yr(-1)), the male:female asthma ratio increased (1:38 in 1974; 1:84 in 1992 and 1:62 in 1998). No single environmental factor, including area of residence, seemed to influence the prevalence of asthma. Family history of asthma and atopy also increased steadily (0.72% x yr(-1) and 0.30% x yr(-1) respectively) more than doubling during the 24-yr study period. The strong relationship between asthma and a family history of atopy not only persisted but also strengthened over time (23.3% of asthmatic children belonged to families with atopic illnesses in 1974 but 44.2% in 1998). The environmental factors that might explain the almost three-fold rise in childhood asthma between 1974 and 1992 remain unknown but the genetic background of the disease has presumably remained unchanged since the early 1970s. The fact that the prevalence of asthma increased no further during the past 6 yrs suggests that the progressive induction of asthma symptoms in genetically predisposed subjects is a self-limiting process that has probably come to an end in the authors' study area.

Off-line exhaled nitric oxide measurements in children.

The concentration of exhaled nitric oxide (eNO) is a useful marker of asthmatic bronchial inflammation. eNO can now be measured away from the laboratory (off-line), even in children. Short exhalation maneuvers (8 sec) and small samples (1 L) of exhaled gas are probably sufficient in children, but more information is needed about the effect of different measurement conditions. As a preliminary step before conducting epidemiological studies in schoolchildren, we investigated the effects of expiratory flow, dead space, and expiratory time on eNO concentrations collected in 1-L mylar collection bags. We studied 101 cooperative subjects (62 males) aged 5-18 years (30 healthy volunteers, 51 asthmatics, and 20 children with various other respiratory diseases) in our pulmonary function laboratory. On-line and off-line eNO were compared in a single session, and analyzed with a Sievers NOA 280 nitric oxide analyzer. For both methods of collecting expired gas, subjects did a single exhalation without breath-holding against an expiratory pressure 10 cm H(2)O. We investigated the effects of expiratory flow, dead space, and exhalation time on eNO; we also compared on-line and off-line eNO measurements, and the repeatability of both techniques at a given flow rate. Expiratory flows of 58 mL/sec provided more reproducible data than lower flows (coefficient of repeatability 1.1 ppb for 58 mL/sec vs. 2.8 for 27 mL/sec vs. 5.7 for 18 mL/sec). eNO concentrations were about 25% higher in off-line than in on-line recordings if the initial 250 mL of exhaled gas were not eliminated, and 37% higher if exhalation lasted longer (16 sec vs. 8 sec). Eliminating 250 mL of dead space and shortening the filling time to 8 sec yielded off-line eNO values close to those on-line (geometric mean off-line eNO 14.4 ppb, 95% confidence interval: 12.2-17.0) vs. on-line eNO 13.8 ppb (95% confidence interval: 11.6-16.5). On-line and off-line results were highly correlated (r = 0.996, P = 0.000) and had similar coefficients of variation (on-line eNO 2.6%, off-line 2.8%). Neither agreement nor repeatability of eNO measurements were affected by disease status or baseline FEV(1) (% predicted values). Once standardized, the off-line eNO technique using 1-L gas collection bags will provide results similar to those recorded on-line.

Changes over 13 years in skin reactivity to histamine in cohorts of children aged 9-13 years.

BACKGROUND: Several studies report substantial differences in the prevalence of skin test reactivity to allergens in children from adjacent geographic areas; others report an increased prevalence over time. To find out whether these differences depend on variations in skin reactivity to histamine, we determined the time trend of histamine wheal sizes in successive cohorts of unselected children living in the same area (Viterbo, Italy). METHODS: We conducted three epidemiologic surveys, each including children aged 9 and 13 years. The 1983-7 study investigated 170 children (150 were tested twice); the 1992 study, 158 children; and the 1996 study, 208 children. RESULTS: In both age groups, the mean diameter of the wheal induced by histamine skin prick tests (10 mg/ml) increased significantly over time (9-year-olds: 3.25 mm in 1983, 4.68 in 1992, and 5.89 in 1996; 13-year-olds: 3.89 mm in 1987, 5.18 in 1992, and 6.50 in 1996) (P < 0.001 between subsequent studies). The distribution of the wheal diameters for both ages showed a trend to a right shift in the three successive studies (P < 0.001). The dose-response curves for three histamine concentrations (0.2, 1, and 10 mg/ml) had significantly steeper slopes in 1996 than in 1983-7 (P < 0.001). CONCLUSION: The marked time-related increase in the size of the histamine wheals could help to explain the trend toward an increased prevalence of positive allergen skin test reactions reported during the past years. The causes of increased skin reactivity to histamine remain conjectural.

Cellular and noncellular components of bronchoalveolar lavage fluid in HIV-1-infected children with radiological evidence of interstitial lung damage.

Children with acquired immune deficiency syndrome (AIDS) commonly have recurrent infectious and noninfectious lung complications that ultimately end in death. To study the intensity of alveolar inflammation and to evaluate the clinical utility of bronchoalveolar lavage (BAL) in children with HIV-1 infections, we retrospectively analyzed differential cell counts, lymphocyte subsets, and fibronectin and hyaluronic acid concentrations in BAL fluid of 18 HIV-1-positive children (9 boys, mean age 3.5 years, range 5 months-8 years) with radiological evidence of interstitial lung disease, and 19 control children who had undergone BAL for clinical indications not involving the lung parenchyma (13 boys, mean age 3 years, range 2 months-14 years). BAL fluid from 89% of the HIV-1 infected children showed CD8+ve lymphocytic alveolitis expressing HLA-DR, CD54, and CD 69 antigens. BAL fluid from HIV-infected patients typically contained markedly increased percentages and numbers of lymphocytes (P < 0.0001) and eosinophils (P < 0.04) and significantly higher concentrations of albumin (P < 0.05) and fibronectin (P < 0.0006) than fluids from control children. Whereas BAL cellular components did not differ in P. carinii-positive and P. carinii-negative HIV-1-infected children, fibronectin concentrations were significantly higher in P. carinii-positive than negative children. BAL cell differentials and noncellular components were related neither to severity of disease nor to patients' disease progression. These findings indicate that BAL is useful in studying the intensity of lung inflammation in children with HIV-1 infections and radiologically documented interstitial lung disease, but provides no information on the subsequent clinical course.

Phylogeny of cytokines: molecular cloning and expression analysis of sea bass Dicentrarchus labrax interleukin-1beta.

In this paper the cloning of interleukin-1beta (IL-1beta) from the fish Dicentrarchus labrax (sea bass) is described. Using degenerate primers designed from known IL-1beta sequences, a cDNA fragment was amplified by PCR and elongated by 3' and 5' RACE to give the full-length coding sequence for sea bass IL-1beta. The cDNA is 1292 bp, lacks a putative ICE cut site, and codes for a deduced peptide of 29.4 kDa with a pI of 5.1. Sequence analysis showed highest amino acid similarity with rainbow trout (62%), Xenopus (46%), and carp (45.5%) IL-1beta sequences. Expression studies show that sea bass IL-1beta can be upregulated by bacterial lipopolysaccharide both in vitro and in vivo in leucocytes from blood, head-kidney, spleen, gills and liver, whereas the IL-1beta transcript was not detectable in thymus and gut-associated lymphoid tissue. Northern blot analysis with head-kidney leucocyte RNA showed a main LPS-upregulated band at 1.3 kb, and two minor bands at 0.9 and 3.0 kb, respectively. Phylogenetic comparisons with IL-1beta from other vertebrates is presented.

Bronchoalveolar lavage cell analysis in a child with chronic lipid pneumonia.

In an asymptomatic 4 yr old child with radiographic evidence of parenchymal lung disease, bronchoalveolar lavage (BAL) yielded the diagnosis of chronic lipid pneumonia caused by chronic aspiration of mineral oil given as a laxative. BAL analysis showed a marked reduction in the total number of alveolar macrophages; almost 70% of these cells contained intracytoplasmic lipid vacuoles. It also disclosed lymphocytic (cytotoxic/suppressor) alveolitis. A high percentage of lymphocytes expressed antigen markers of activation (human leucocyte antigen (HLA)-DR), CD54 and CD25). BAL analysis 18 months after mineral oil intake revealed that lymphocytes bearing antigen markers of activation had markedly decreased whereas alveolar macrophages (normal and lipid-laden) had increased. A subsequent whole lung BAL was considered unnecessarily invasive in this otherwise healthy child.

Immune response against Trypanosoma cruzi antigens in Cebus apella monkeys.

The american primate Cebus apella has been used as an experimental model for the study of acute and chronic Chagas' disease. The antibody response elicited by 4 x 10(6) blood trypnomastigotes injected into four monkeys was analysed. Peak titres of IgM and IgG of anti-Trypanosoma cruzi antibodies were found at day 22, and between days 20 and 40 post-infection (p.i.), respectively. The ability of a Mr 37kDa (T37K) glycoprotein purified from T. cruzi epimastigotes to generate IgG anti-T. cruzi antibodies in monkeys, and protect them against a challenge with trypomastigotes, was also studied. Monkeys non-immunized with T37K reached peak values of parasitaemia between days 18 and 21 post-infection, whereas immunized monkeys had lower parasitaemias without important variation. Anti-T37K antibodies in immunized monkeys decreased from day 2 with the lowest titres between days 14 to 22 p.i., coincident with the peak of parasitaemia in control non-immunized monkeys. These results suggest that anti-T37K antibodies could be responsible for the low parasitaemia detected in immunized monkeys.

Gastric acid secretion response in the Cebus apella. A monkey model of chronic Chagas' disease.

The objective was to study the secretory pattern, both basal and stimulated either by histamine (0.1 mg/kg) or pentagastrin (64 micrograms/kg) in eighteen Cebus apella monkeys chronically infected with different T. cruzi strains (CA1, n = 10; Colombian, n = 4 and Tulahuen, n = 4) and to describe the morphological findings in the gastrointestinal tract in twelve infected (6 sacrificed and 6 spontaneously dead) and four healthy monkeys. All infected monkeys and 35 healthy ones were evaluated by contrast X-ray examination. No differences were observed in basal acid output between control and infected groups. Animals infected with the Tulahuen and Colombian strains showed significant lower values of peak acid output in response to histamine or pentagastrin (p < 0.01 and p < 0.05 respectively; "t" test) in comparison to the controls. Barium contrast studies showed enlargement and dilatation of the colon in three infected animals. Histopathological lesions were seen in 75% of the autopsied animals either in colon alone (33%) or both, in colon and esophagus (42%). The normal secretion observed in the CA1 infected group could be due to a lower virulence of the strain, a lower esophageal tropism or the necessity of a longer post-infection time to cause lesions.

Electrocardiographic changes in chronic Trypanosoma cruzi infected Cebus apella monkeys.

PURPOSE: To evaluate electrocardiographic data of Cebus apella monkeys with Chagas' disease. MATERIAL AND METHODS: 53 Cebus apella monkeys (juvenile and adult of both sexes) were used: 35 as a control group and 18 inoculated four-five years ago with 3 different Trypanosoma cruzi strains (CA1, n = 10; Colombian, n = 4; Tulahuen, n = 4). RESULTS: The normal electrocardiogram (ECG) showed differences with that of man, a) high cardiac rate; b) presence of "pulmonary p" wave without pulmonary pathology. The ECT alterations found between 11 and 58 months after last inoculation were: right bundle branch block; intermittent right bundle branch block; left ventricle overload; repolarization disturbances; left anterior hemiblock; extra systole. These alterations resemble those found in humans, as well as clinical parasitological and immunological alterations. Their incidence and the time at which they appeared, seem to vary according to the route, strain, inoculum and frequency of the inoculation. Three of the monkeys died spontaneously 46, 48 and 52 months after the infections due to the natural evolution of the disease, and six were sacrificed during the follow-up. In both cases histopathological lesions were found, and their intensity was directly related to the time and resembled the human disease. CONCLUSION: The Cebus apella, as it reproduces human electrocardiographic and histopathological alterations, a short time after experimental infection, is a suitable model for the study of the different aspects of the physiopathology, immunopathology and therapeutics of the indeterminate and chronic phases of Chagas' disease.

Chronic myocardial damage in experimental T. cruzi infection of a New World primate, Cebus sp. monkey.

Eighteen Cebus apella monkeys, (juvenile and adult of both sexes) were inoculated five years ago, with three Trypanosoma cruzi strains (CA1, n = 10; Colombian, n = 4 and Tulahuen, n = 4), either by conjunctival or intraperitoneal route, once or repeatedly. Parasitological, hematological, serological, enzymatic, radiographic, electro and echocardiographic findings have been previously published and they are similar to those observed in human pathology. The most frequent electrocardiographic alteration was right branch bundle block. Six animals, chosen at random, were sacrificed. Those sacrificed 20 to 25 months post-first inoculation showed focal accumuli of leukocytes with myocytolysis. Foci of diffuse interstitial fibrosis with mild infiltrate of leukocytes among fibers were observed in the animals sacrificed 36 to 47 months post-inoculation. No parasites were seen. The lesions were more prominent in the ventricular walls and the septum. The fact that the infiltrates were predominant in the animals sacrificed at a shorter time after first inoculation and that fibrosis was more severe in those sacrificed at a longer time suggests that there is a progression of the infiltrative lesions to fibrosis, with a leukocytic activity indicative of a chronic phase. These lesions are similar to those described in human chronic Chagas' disease. This would demonstrate that this model is useful in evaluating a progress in the knowledge of the pathogenesis which is still a controversial issue, immunology, immunogenesis and chemotherapeutic agents of the chronic and indeterminate phases of this disease.

Influence of jejunal hypertonic glucose infusion on sham-feeding-stimulated gastric acid secretion: evidence of a defective mechanism in duodenal ulcer patients.

The aims of the present study were to determine in 14 healthy subjects and 14 duodenal ulcer patients the reproducibility of the acid secretory response to a modified sham-feeding test and the effect on this response of intrajejunal hypertonic glucose instillation, in order to evaluate the possibility of the existence of a defective inhibition of the cephalic phase of gastric acid secretion in duodenal ulcer disease. The reproducibility of the acid secretory response to a modified sham-feeding test was demonstrated in both groups in two consecutive tests. The hypertonic glucose instillation produced a significant inhibition of the acid secretory response to modified sham feeding only in the healthy subjects, suggesting that duodenal ulcer patients may have a defective mechanism of acid inhibition during vagal stimulation by modified sham feeding. Non-significant changes were observed in plasma gastrin and pancreatic glucagon levels.

Humoral and cellular parameters of the immune system of Cebus apella monkeys. Cross reactivity between monkey and human immunoglobulins.

The humoral and cellular immunological parameters of the New World non-human primate Cebus apella were analysed. The study included: serum protein immunoelectrophoretic analysis; cross reactivity between monkey and human immunoglobulins by immunoprecipitation, ELISA and indirect immunofluorescence tests; immunoglobulin quantitation by radial immunodiffusion; and assays with peripheral blood lymphocytes involving tests for E and EAC rosettes and detection of surface markers (surface immunoglobulins and CD4-CD8 antigens). The results obtained showed that (a) at least three immunoglobulins with electrophoretic mobility corresponding to IgG, IgA and IgM which showed cross reactivity with the human ones were present in serum; (b) it was possible to evaluate the relative monkey immunoglobulin concentration using specific antibodies against human immunoglobulins and to obtain absolute values using adequate conversion factors; (c) lymphocytes forming E and EAC rosettes were found in peripheral blood in a similar proportion to that reported in man; (d) lymphocyte surface immunoglobulins were detected using anti-human immunoglobulin serum; (e) it was not possible to demonstrate the presence of T helper and T suppressor/cytotoxic lymphocytes using OK T4 and OK T8 monoclonal antibodies.

Determinations of serum and muscle magnesium in Cebus monkeys infected with different T. Cruzi strains

Se midió magnesio (Mg++) sérico y musuclar en monos Cebus apella infectados con diferentes cepas de T. cruzi (CA1, Colombiana y Tulahuén). Los animales se dividieron en cuatro grupos: 1) control (n = 6); 2) CAI (n = 7); 3) Colombiana (n = 2), y 4) Tulahuén (n = 3), según el diseño experimental que se observa en la Tabla 1. En todos los grupos se realizó una biopsia del tensor faciae latae para determinar el Mg++ muscular mediante espectrofotometría de absorción atómica y simultáneamente se tomaron muestras de sangre de la vena femoral para medir magnesemia por complejación, durante la etapa crónica d ela enfermedad. No se observaron diferencias estadísticas, por análisis de varianza, entre los diferentes grupos (Tabla 2). Por lo tanto, podemos inferir que la enfermedad de Chagas no modifica per se los valores de Mg++ sérico y muscular

Determinations of serum and muscle magnesium in Cebus monkeys infected with different T. Cruzi strains

Se midió magnesio (Mg++) sérico y musuclar en monos Cebus apella infectados con diferentes cepas de T. cruzi (CA1, Colombiana y Tulahuén). Los animales se dividieron en cuatro grupos: 1) control (n = 6); 2) CAI (n = 7); 3) Colombiana (n = 2), y 4) Tulahuén (n = 3), según el diseño experimental que se observa en la Tabla 1. En todos los grupos se realizó una biopsia del tensor faciae latae para determinar el Mg++ muscular mediante espectrofotometría de absorción atómica y simultáneamente se tomaron muestras de sangre de la vena femoral para medir magnesemia por complejación, durante la etapa crónica d ela enfermedad. No se observaron diferencias estadísticas, por análisis de varianza, entre los diferentes grupos (Tabla 2). Por lo tanto, podemos inferir que la enfermedad de Chagas no modifica per se los valores de Mg++ sérico y muscular (AU)