Pericentric chromosome 8 inversion associated with the 5?RUNX1/3?CBFA2T1 gene in acute myeloid leukemia cases

In the present paper we report pericentric chromosome 8 inversions in two (2.4%) of 82 acute myeloid leukemia (AML) cases characterized by the 5'RUNX1/3'CBFA2T1 fusion gene. Molecular cytogenetic characterization was achieved using appropriate bacterial artificial chromosome (BAC) and P1 artificial chromosome (PAC) probes in fluorescence in situ hybridization (FISH) experiments. In these two cases the fusion gene was detected on the der(8) short arm, resulting from a pericentric chromosome 8 inversion followed by a t(8;21) rearrangement. These results suggest that heterogeneous mechanisms can lead to the generation of the 5'RUNX1/3'CBFA2T1chimeric gene.

Adherence to antiretroviral therapy and its determinants in children with human immunodeficiency virus infection: a multicentre, national study

AIM

To investigate rates and determinants of adherence to antiretroviral therapy in Italian children infected with the human immunodeficiency virus (HIV).

METHODS

An observational, cross-sectional multicentre study was performed through a structured interview with the caregivers of HIV-infected children. The interview included quantitative information on adherence in the 4 d before interview. Sociodemographic, clinical and psychosocial characteristics of children were recorded.

RESULTS

129 children (median age 96 mo) were enrolled, of whom 94 were on highly active antiretroviral therapy (HAART). Twenty-one (16%) omitted more than 5% of total doses in 4 d and were considered non-adherent. However, only 11% of caregivers reported that therapy had been administered at the correct times. No significant difference was found between age and the stage of HIV infection. Children aware of their HIV status were less adherent. Individual drugs showed a broad adherence pattern and children who received HAART were more adherent. Children receiving therapy from foster parents were more adherent than those receiving drugs from biological parents or relatives.

CONCLUSIONS

Adherence is a major problem in children. Psychological rather than clinical or sociodemographic features and types of drug are major determinants of adherence.

A novel chromosomal translocation t(3;7)(q26;q21) in myeloid leukemia resulting in overexpression of EVI1

The EVI1 proto-oncogene encodes a nuclear zinc finger protein that acts as a transcription repressor factor. In myeloid leukemia it is often activated by chromosomal rearrangements involving band 3q26, where the gene has been mapped. Here we report two leukemia cases [a chronic myeloid leukemia blast crisis (CML-BC) and an acute myeloid leukemia (AML) M4] showing a t(3;7)(q26;q21) translocation in a balanced and unbalanced form, respectively. Fluorescent in situ hybridization (FISH) analysis revealed that both patients showed a breakpoint on chromosome 3 inside the clone RP11-33A1 containing the EVI1 oncogene and, on chromosome 7, inside the clone RP11-322M5, partially containing the CDK6 oncogene which is a D cyclin-dependent kinase gene, observed to be overexpressed and disrupted in many hematological malignancies. Reverse transcriptase polymerase chain reaction (RT-PCR) analysis showed overexpression of EVI1 in both cases, but excluded the presence of any CDK6/ EVI1 fusion transcript. CDK6 expression was also detected. Together, these data indicate that EVI1 activation is likely due not to the generation of a novel fusion gene with CDK6 but to a position effect dysregulating its transcriptional pattern.

Short duration of breastfeeding and early introduction of cow's milk as a result of mothers' low level of education

Inappropriate infant feeding including a lack of breastfeeding and the early introduction of cow's milk are the most common forms of infant feeding malpractice. To evaluate the hypothesis that infant feeding malpractices are associated with mothers' low level of education, questionnaires were administered to 400 mothers of infants below 12 mo of age divided into 3 groups according to their various educational levels. Items included the type of milk given at birth and at 1, 3 and 6 mo of age. To investigate the efficacy of paediatricians in orienting infant feeding, the same questionnaire was given to 30 paediatricians in primary paediatric healthcare, in hospitals or in private practices. Initiation of breastfeeding was similar in the three groups. An analysis of the data showed that an increasing number of infants born to mothers of low and intermediate educational level did not receive exclusive breastfeeding compared with those with a higher level of education, a difference that was significant as early as 1 mo of age. In infants aged 3 mo, the prevalence of exclusive breastfeeding was 37%, 40% and 65% in the three groups, respectively, in relation to progressively increasing levels of education. In infants of 6 mo, the respective prevalence rates were 13%, 15% and 48%. Early introduction of cow's milk showed a similar correlation with educational level. A greater number of infants born to mothers with a low level of education received cow's milk at 3 mo of age compared with those born to mothers with an intermediate education (12% vs 5%). A similar difference was observed between the latter group and infants born to mothers with a high educational level (0%). This pattern was supported by data for infants at 6 mo of age with prevalence rates for cow's milk feeding of 39%, 20% and 0% in the three groups in association with progressively increasing level of educational (p < 0.05). The analysis of the paediatricians' response to the questionnaire showed that while physicians know and correctly prescribe age-related infant nutrition regimens, they are unaware that a substantial number of mothers do not comply with what they prescribe. Overall, these data support the relationship between a low educational level and infant feeding malpractice and suggest that a more effective role should be played by paediatricians in supporting an adequate duration of breastfeeding and the use of formula rather than cow's milk protein.

Deletions on der(9) chromosome in adult Ph-positive acute lymphoblastic leukemia occur with a frequency similar to that observed in chronic myeloid leukemia

The t(9;22)(q34;q11), generating the Philadelphia chromosome (Ph), is found in more than 90% of patients with chronic myeloid leukemia (CML) and in 15-30% of adults with acute lymphoblastic leukemia (ALL). Different groups have recently described the presence of large genomic deletions adjacent to the translocation breakpoint on the derivative chromosome 9 in 9-16% of CML patients. In the present paper, we report a FISH study of 45 Ph+ adult ALL patients with the aim of investigating the presence of deletions on derivative chromosome 9. In four (9%) of 45 cases, all showing an M-bcr, we detected deletions on der(9). The frequency of deletions we observed is similar to that reported in CML patients. The association of an M-bcr breakpoint and deletions appears significant (P=0.03). Some authors have suggested a very low incidence of der(9) deletions in ALL. This discrepancy can be explained by taking into account the low percentage of M-bcr ALL patients in the latter study (18%) compared to the present one (44%).

Extramedullary involvement at relapse in acute promyelocytic leukemia patients treated or not with all-trans retinoic acid: a report by the Gruppo Italiano Malattie Ematologiche dell'Adulto

PURPOSE

Recent reports of extramedullary disease (EMD) at recurrence in acute promyelocytic leukemia (APL) have raised increasing concern about a possible role of retinoic acid (RA) therapy.

PATIENTS AND METHODS

We analyzed the risk of developing EMD localization at relapse in APL patients enrolled onto two consecutive studies of the Gruppo Italiano Malattie Ematologiche dell'Adulto. The studies investigated chemotherapy alone (LAP0389) versus RA plus chemotherapy (AIDA).

RESULTS

When all relapse types were taken into account, 94 (51%) of 184 patients and 131 (18%) of 740 patients who attained hematologic remission underwent relapse in the LAP0389 and AIDA studies, respectively (P < .0001). EMD localization was documented in five (5%) of 94 and 16 (12%) of 131 patients (P = .08). Hematologic and/or molecular relapse was diagnosed concomitantly in all but two patients with EMD in the AIDA study. For patients in the LAP0389 and AIDA series, the probability of EMD localization of any type at relapse was 3% and 4.5%, respectively (P = .79), while the probability of CNS involvement was 0.6% and 2% (P = .28). No significant differences were found with regard to mean WBC count and promyelocytic leukemia/retinoic acid receptor-alpha junction type in comparisons of patients with EMD and hematologic relapse.

CONCLUSION

APL patients receiving all-trans retinoic acid in addition to chemotherapy have no increased risk of developing EMD at relapse as compared with those treated with chemotherapy alone.

Retinal abnormalities in newly diagnosed adult acute myeloid leukemia

Retinal abnormalities (RA) are very frequently observed in adult patients with acute myeloid leukemia (AML), but the clinical significance of these findings has not been fully investigated. We examined the fundus oculi in a cohort of 122 adult patients with AML at presentation and analyzed some clinical and biological features to assess whether there was any association with RA. For this purpose, we subdivided the patients into two groups according to the presence or absence of RA (groups 1 and 2, respectively). We considered current laboratory parameters such as white blood cell (WBC) count, hemoglobin (Hb), platelets and serum lactate dehydrogenase (LDH). Moreover, we subdivided the patients into two groups according to age <60 (group A) or > or =60 years (group B) to evaluate a possible association between RA and response to treatment and/or overall survival (OS). In our series, a higher median age and a lower Hb value were associated with group 1 (p = 0.001 and p = 0.04, respectively); the median LDH value was 812 U/l (range 224-5,551) and 607 (range 181-5,244) for groups 1 and 2, respectively (p = 0.02). There was no association between RA and karyotypic alterations. In terms of outcome, in group A (<60 years), 80% patients who achieved complete remission (CR) were in group 2 vs. 13% nonresponders (NR) (p < 0.0001). Median OS of group 2 patients was 49.7 months compared with 7.2 months for those in group 1 (p = 0.002). In group B, 58% patients who achieved CR were in group 1 vs. 15% NR (p < 0.006). Median OS of patients in group 2 was 14.6 months compared with 2.9 months in group 1 (p = 0.02). Our data show that RA are significantly associated with some biological features and with shorter OS in AML patients and this parameter seems to be an effective clinical sign of poor prognosis in terms of CR.

Colonocyte basolateral membranes contain Escherichia coli heat-stable enterotoxin receptors

Heat-stable enterotoxin (ST(a)) elaborated by E. coli is a major cause of diarrhea. The transmembrane protein guanylyl cyclase C (GC-C) is the acknowledged receptor for ST(a) and for the mammalian peptides guanylin and uroguanylin. Binding to GC-C results in generation of cGMP, activation of type II cGMP-dependent protein kinase, phosphorylation of CFTR and increased chloride and bicarbonate secretion. We had previously shown that ST(a) receptors (GC-C) are found on the brush border membranes of small intestinal enterocytes and of colonocytes. However, since it has subsequently been shown that the endogenous ligands for these receptors, guanylin and uroguanylin, circulate in blood, we proposed the existence of ST(a) binding sites on the basolateral membranes (BLM) of colonocytes. Specific binding of 125I-ST(a) to rat colonocyte BLM was seen. The kinetics of binding to the BLM were similar to binding to BBM. The nature of the BLM receptor is unknown. This suggests that circulating guanylin and uroguanylin, analogues of ST(a), may also function via the basolateral surface.

Biochemical behaviour of norbixin during in vitro DNA damage induced by reactive oxygen species

Naturally occurring antioxidants such as carotenoids are extensively studied for their potential in reducing the risk for cancer and other chronic diseases. In the present study, the radical-scavenger activity of the food additive norbixin, a water-soluble carotenoid extracted from Bixa orellana seeds and commercialized as annatto, was evaluated under conditions of DNA damage induced by reactive oxygen species, particularly by hydroxyl radicals. The cell-free scavenger activity of norbixin was evaluated using plasmid DNA as target molecule and Sn2+ or Fe2+ as oxidant. The addition of H2O2 enhanced DNA breakage induced by metal ions, particularly Fe2+. Under these conditions, norbixin started to protect plasmid DNA against single- and double-strand breakage at a metal:norbixin ratio of 1:1 (Sn2+) and 1:10 (Fe2+). However, at lower ratios to Sn2+, norbixin enhanced Sn2+-induced DNA breakage (P < 0.05). The ability of norbixin to protect genomic DNA against oxidative damage was assessed in murine fibroblasts submitted to H2O2-induced oxidative stress and the results were evaluated by the comet assay. Under low serum conditions (2 % fetal bovine serum (FBS)), a protective effect of norbixin against H2O2-induced DNA breakage was inversely related to its concentration, a protection ranging from 41 % (10 microm) to 21 % (50 microm). At higher concentrations of norbixin, however, oxidative DNA breakage was still enhanced, even in the presence of a high serum concentration (10 % FBS). Under normal conditions, norbixin per se has no detectable genotoxic or cytotoxic effects on murine fibroblasts. The antimutagenic potential of norbixin against oxidative mutagens was also evaluated by the Salmonella typhimurium assay, with a maximum inhibition of 87 % against the mutagenicity induced by H2O2. Although plasmid DNA and Ames data indicated that norbixin can protect DNA against oxidative damage, it seems to be a risky guardian of genomic DNA as it can also increase the extent of oxidative damage.

The effect of electromagnetic field exposure on the formation of DNA lesions

In an attempt to determine whether electromagnetic field (EMF) exposure might lead to DNA damage, we exposed SnCl2-treated pBR322 plasmids to EMF and analysed the resulting conformational changes using agarose gel electrophoresis. An EMF-dependent potentiation of DNA scission (i.e. the appearance of relaxed plasmids) was observed. In confirmation of this, plasmids pre-exposed to EMF also were less capable of transforming Escherichia coli. The results indicate that EMF, in the presence of a transition metal, is capable of causing DNA damage. These observations support the idea that EMF, probably through secondary generation of reactive oxygen species, can be clastogenic and provide a possible explanation for the observed correlation between EMF exposure and the frequency of certain types of cancers in humans.

Bone marrow aspirate on the 14th day of induction treatment as a prognostic tool in de novo adult acute myeloid leukemia

BACKGROUND AND OBJECTIVES

In adult acute myeloid leukemia (AML), a variety of clinical and biological parameters have been examined for their potential value in predicting treatment response. Early response to induction therapy could be an important prognostic factor in this disease.

DESIGN AND METHODS

We studied the relationship between reduced blasts in bone marrow aspirate on the 14th day (BMA14th) of induction chemotherapy and treatment outcome in 198 adult AML patients of whom 124 were < 60 years old (group A) and 74 > or = 60 years old (group B). Receiver operating characteristic curve analysis was used to assess the prognostic performance of BMA14th. Using the percentages of blasts of < or = 22% and < or = 15% as criteria for predicting treatment outcome gave the highest accuracy in terms of sensitivity and specificity in groups A and B, respectively.

RESULTS

In group A, of 97 patients with a BMA14th < or = 22%, 77 (79%) achieved complete remission (CR), whereas of 27 patients with a BMA14th > 22%, 22 (81%) were non-responders (NR) (p < 0.0001). The test sensitivity and specificity were 93.9% and 71.4%, respectively. In group B, of 27 patients with a BMA14th < or = 15%, 18 (67%) achieved CR, whereas of 47 patients with a BMA14th >15%, 38 (81%) were NR (p = 0.0001). The test sensitivity and specificity were 66.7% and 80.9%, respectively.

INTERPRETATION AND CONCLUSIONS

Our data suggest that BMA14th may be a predictive test for CR, helping to identify NR patients early in their disease. Further studies are needed to establish the practical implications of the results of our study.

Structural and functional features of modified heat-stable toxins produced by enteropathogenic Klebsiella cells

Heat-stable enterotoxins (STs) are 18- or 19-amino acid peptides (STa or ST1) produced by enteropathogenic bacteria with small differences in their amino acid sequence and a highly conserved carboxy terminus. All STs contain a core of three disulfide bridges whose integrity is believed to be necessary for full biologic activity. We previously reported that strains of Klebsiella pneumoniae transformed by the plasmid pSLM004 produce a modified toxin not recognized by MAb raised against genuine Escherichia coli ST. Investigation of the chemical structure of the modified toxins revealed that three new toxins were present. These were purified to homogeneity by a series of sequential chromatography on reverse-phase columns using guanylate cyclase to monitor the enterotoxic activity during purification procedures. The sequence of the modified toxins was obtained by a combination of Edman degradation and mass spectrometry, showing that they are proteolytically processed forms of E. coli ST1b. In particular, toxin A-2 lacks the cysteine at position 18 and then is not able to form the disulfide bridge cysteine-10-cysteine-18. All three toxins showed the ability to stimulate guanylate cyclase and to elicit chloride secretion in Caco-2 cell monolayers mounted in Ussing chambers. Toxin A-1 and toxin B demonstrated greatly reduced immunoreactivity whereas toxin A-2 was not recognized at all in the ELISA. It is likely that the three modified toxins were generated by Klebsiella specific proteolytic processing of the original pretoxin. These results have important implications for the diagnosis and prevention of heat-stable toxin-induced diarrhea.

Toxicological evaluation by in vitro and in vivo assays of an aqueous extract prepared from Echinodorus macrophyllus leaves

Toxicity of an aqueous extract prepared from Echinodorus macrophyllus dried leaves, a plant used in folk medicine to treat inflammation and kidney malfunctions, was estimated by different bioassays. Mutagenicity of the aqueous extract was evaluated in the Salmonella/microsome assay (TA97a, TA98, TA100 and TA102 strains), with or without metabolic activation. No mutagenic activity (lyophilized extract tested up to 50 mg/plate) could be detected to any of the tester strain. Furthermore, no cytotoxic effect has been observed when a crude extract of E. macrophyllus (up to 7.5 mg/ml) was tested on the exponential growth of hepatoma and normal kidney epithelial cells in culture. Toxicity of E. macrophyllus was also evaluated in male Swiss mice after 6 weeks of continuous ingestion of the aqueous extract in drinking water. Average daily ingested doses were 3, 23 and 297 mg/kg for a lyophilized extract, and 2200 mg/kg for a crude extract, with dose two being equivalent to the daily dose recommended to humans. At the end of the treatment, all animals revealed a deficit in final body weight ranging from 5 to 47%. Biochemical analysis of the plasma revealed some minor alterations indicating subclinical hepatic toxicity. Genotoxic effect on liver, kidney and blood cells has been also evaluated by the comet assay, being negative to liver and blood cells. However, DNA analyses of the kidney cells detected some genotoxic activity for the highest dose tested of E. macrophyllus extract, either lyophilized or crude. On the other hand, exposure dose of 23 mg/kg, equivalent to the daily dose recommended to humans, did not revealed any genotoxic effect and hence this herb seems to be safe to human organism.

Adherence to antiretroviral therapy in HIV-infected children in Italy

Adherence to antiretroviral therapy is a major problem in children with HIV infection, who depend on parents or foster parents for receiving drugs. During an ongoing investigation on intestinal function in children with symptomatic HIV infection who were treated with zidovudine, blood samples were obtained six hours after the administration of zidovudine as reported by the parents and, again, one and six hours after its administration in the hospital, and drug concentration was measured by radioimmunoassay. Both peak and steady state zidovudine levels were within the expected concentration ranges after administration in the hospital. In contrast, they were below the effective concentration in five of the 10 children that reportedly had received the drug at home by the parents. These data directly show poor compliance with antiretroviral therapy in children. Compliance with antiretroviral therapy should be carefully checked in children and strategies are needed to increase full and permanent adherence with antiretroviral therapy by people in charge to administer drugs to HIV-infected children.

[Acute infectious diarrhea in children]

Infantile acute gastroenteritis is still a frequent problem particularly in younger children, with high mortality rate in developing countries and high impact on health costs in industrialized countries. The increased knowledge on its pathophysiology has led to the definition of two distinct mechanisms of diarrhea: the secretory and the osmotic pathway. Investigation on the host-microorganism interaction revealed a complex scenario with sophisticated mechanisms developed by microorganisms during evolution to overcome the host defense system. The latter includes immune and non immune coordinated components, with a major role played by the GALT (gut associated lymphoreticular tissue). Knowledge of epidemiology and of the natural history of intestinal infections has led to rational diagnostic approach with substantial cut of medical costs. Novel therapeutic strategies have been made available with the use of probiotics and of passive immunotherapy together with a dramatic reduction of antibiotic treatment. HIV pandemy raises major problems which need rapid responses.

Oral bacterial therapy reduces the duration of symptoms and of viral excretion in children with mild diarrhea

BACKGROUND

Oral administration of live Lactobacillus casei strain GG is associated with the reduction of duration of diarrhea in children admitted to the hospital because of diarrhea. The purposes of this work were to investigate the clinical efficacy of oral administration of Lactobacillus in children with mild diarrhea who were observed as outpatients, and to see whether Lactobacillus GG can reduce the duration of rotavirus excretion.

METHODS

Duration of diarrhea was recorded in 100 children seen by family pediatricians and randomly assigned to receive oral rehydration or oral rehydration followed by the administration of lyophilized Lactobacillus casei, strain GG. Rotavirus was looked for in the stools of all children and in those in whom results were positive, stools were examined again 6 days after the onset of diarrhea.

RESULTS

In 61 children results were positive for rotavirus and in 39 results were negative. Duration of diarrhea was reduced from 6 to 3 days in children receiving Lactobacillus GG, with a similar pattern in rotavirus-positive and -negative children. Six days after the onset of diarrhea, stools in only 4 out of 31 children that received Lactobacillus GG were positive for rotavirus compared with positive findings in 25 out of 30 control subjects.

CONCLUSIONS

Oral administration of Lactobacillus GG is effective in rotavirus-positive and rotavirus-negative ambulatory children with diarrhea. Furthermore, it reduces the duration of rotavirus excretion.

Iron deficiency and intestinal malabsorption in HIV disease

Children with human immunodeficiency virus (HIV) infection have a higher prevalence of intestinal malabsorption. Anemia is also a common feature in these children. The aims of this work were (a) to establish the prevalence of iron deficiency in HIV-infected children, (b) to test the hypothesis that iron deficiency is related to intestinal malabsorption, (c) to see whether it may contribute to anemia, and (d) to evaluate the sensitivity of oral iron load in the investigation of intestinal function. To accomplish these goals, 71 HIV-infected symptomatic children were enrolled. Iron serum values were determined before and after oral load with ferrous sulfate. The correlation between basal and post-load iron levels was evaluated by linear regression. Xylose level after oral load, fecal fat, and fecal alpha 1-antitrypsin concentration were also determined. Iron deficiency was detected in 48% of patients, and it was significantly associated with intestinal iron malabsorption. Sugar malabsorption, steatorrhea, and fecal protein loss were detected in 26, 36, and 17% of patients, respectively. Low hemoglobin levels were detected in 66% of patients. The majority of children with iron deficiency also had anemia. Preliminary data showed that oral iron administration was sufficient for raising hemoglobin in children with normal iron absorption, whereas parenteral administration was required in those with iron malabsorption. We conclude that (a) iron deficiency is a major feature of pediatric HIV infection, (b) it is related to intestinal malabsorption, and (c) it contributes to anemia. Finally, oral iron load is a sensitive test for investigating intestinal function.

Unusual transformation of the 3-hydroxy-picolinoyl residue of pristinamycin IA

Pristinamycin IA was modified in a two-step procedure to give original derivatives possessing a tricyclic nucleus (8a, 8b, 8c) or a substituted pyrrole ring (10a, 10b) in place of the natural exocyclic 3-hydroxy-picolinoyl residue. This transformation involved firstly preparation of pyridinium betaines 5 from pristinamycin IA and secondly a 1-3 dipolar cycloaddition between 5 and N-substituted maleimides or diethyl acetylenedicarboxylate. The compounds obtained were evaluated as antibacterial agents alone and in association with pristinamycin IIA.

Etiology and risk factors of severe and protracted diarrhea

Severe and protracted diarrhea (SPD) is the most severe form of diarrhea in infancy and has also been defined as intractable diarrhea. Its etiology is poorly defined. We have retrospectively evaluated the etiology, the outcome, and the risk factors of 38 children, admitted with protracted diarrhea and need for total parenteral nutrition (TPN) from 1977 to 1993. Children with anatomic abnormalities and/or primary immunodeficiency were excluded. There was an inverse relationship between the number of patients and the age of diarrheal onset (mean age, 2.9 +/- 3.5 months). Etiology of SPD was an enteric infection in 18 cases (eight Salmonella, three Staphylococcus, five rotavirus, one adenovirus, one Cryptosporidium), multiple alimentary intolerance (eight cases), familial microvillous atrophy (two), autoimmune enteropathy (two), celiac disease, lymphangectasia, eosinophilic enteropathy, intestinal pseudoobstruction, and intestinal neurodysplasia (1 case each). Etiology was not detected in three cases. Overall, 12 children died, five are presently being treated, and 21 had full remission. Comparative evaluation of risk factors between children with SPD and a control population of children with diarrhea but without the need for TPN showed that low birth weight, no breast feeding, history of fatal diarrhea in a relative, and early onset of diarrhea had a significantly higher incidence in the former. Social background was similar in the two populations. We conclude that a specific etiology can be identified in the majority of cases of SPD. The etiologic spectrum of SPD is broad, but an enteric infection is the most common cause of SPD. The severity of this condition is related, at least in part, to established risk factors.

Enterotoxic effect of stool supernatant of Cryptosporidium-infected calves on human jejunum

BACKGROUND/AIMS

The clinical pattern of cryptosporidial diarrhea suggests an enterotoxic mechanism. No evidence for this mechanism has been reported thus far. This study aimed to look for enterotoxic effect elaborated by Cryptosporidium.

METHODS

The effects on human intestinal transport of stool supernatant of diarrheal calves infected with Cryptosporidium parvum were examined. Aliquots of centrifuged and filtered stools were added to the mucosal or serosal side of human jejunum obtained from patients undergoing surgery and mounted in Ussing chambers. Electrical parameters were recorded. Stool supernatants of uninfected calves served as a control.

RESULTS

The mucosal addition of 2.5 mg protein of fecal supernatant from diarrheal calves induced a prompt and significant increase in short circuit current with no effects on tissue conductance. The serosal addition of this material and the addition of control supernatant to either side did not induce modifications of electrical parameters. The enterotoxic effect was dose-dependent and saturable. It was reversible by withdrawing the supernatant from the incubation medium. The electrical effect was chloride- and calcium-dependent and was sensitive to heating.

CONCLUSIONS

An enterotoxic activity is present in the stools of Cryptosporidium-infected calves. This activity may be responsible for secretory diarrhea in humans.