Prevalencia de eschericia coli enterohemorrágico en una zona ganadera de Argentina: caracterización genotípica de las cepas de origen animal / Animal reservoir and genotipic characterization of enterohemorrhagic escherichia coli in Argentina

Background: There is a high prevalence of infection by Enterohemorrhagic Escherichia coli (EHEC) and patients with hemolytic uremic syndrome (HUS) in Argentina. Aim: To study cattle and pigs as a possible reservoir of EHEC in Argentina. Material and methods: One hundred two healthy animals (68 cattles and 31 pigs) from a livestock in Argentina, were studied. Stool samples were obtained with a rectal swab. The strains were identified by DNA hybridization with specific gene probes detecting Shiga-like toxin 1 and 2 (Stx1, Stx2), and hly gen related to fimbrial adhesin-associated plasmid. EHEC strains were serogrouped using comercial antisera. Results: EHEC was isolated from 30 out of 68 bovines cultures (44.1 percent) and from 25 out of 31 pigs (58.1 percent). Isolates carrying genes codifying both Stx1 and Sxt2, were observed in 50 percent of cattle and 63.9 percent of pigs. The gene which codifies for hemolysin (associated to fimbrial adhesin) was observed in about 41 percent of EHEC isolates. Strains belonging to serogroups O26, O111, and O157 were isolated from cattle, and O111, and O157 from pigs. Conclusions: The high percentage of EHEC in both cattle and pigs and the presence of human infection-associated serogroups, suggests that these animals are a reservoir of EHEC associated with disease in humans

Sensibilidad a la insulina: ausencia de diferencias sexuales al expresarla en función de la masa magra / Insulin sensitivity: absence of sexual differences when expressed as a function of lean body mass

The hyperinsulinemic, euglycemic clamp techinque was used to test the hypothesis that - when expressed per kiligram of lean body mass - there is a sex-difference in peripheral insulin-mediated glucose disposal (M), as proposed in the literature. Lean body mass wass assessed with tetrapolar bioelectric impedance analysis. We studied 15 normal subjects (volunteers with normal glucose tolerance and body mass indices between 20-25 Kg/m2) of both sexes, 9 women and 6 men, of age-groups, 20-30 year-old and 40-50 year-old. Men and women were similarly aged (33.3 ñ 3.8 and 33.3 ñ 3.8 years, respectively). body mass indices were similar in both sexes (22.5 ñ 0.6 in women and 23.6 ñ 0.7 in men, NS) but percentages of fat mass were not (294 ñ 1.2 in women and 20.6 ñ 1.6 in men, p < 0.001). As no difference in M (mg of glucose metabolized per kilogram of body weight per minute) between age-groups was found (6.4 ñ 0.8 snf 6.8 ñ 1.2 mg/Kg/min, Ns) the data from these 2 age-groups were pooled. When M values obtained in both sexes were compared no differences were found (7.1 ñ 1.5 mg/Kg/min in women and 6.3 ñ 0.6 in men, NS). Similarly, when M was expressed in function of the prevailing insulin levels attained during steady-state, M/l, no differences were disclosed (8.98 ñ 2 mg/Kg/min/µIU insulin in women and 7.8 ñ 1.2 in men, NS). When M was expressed per kilogram of lean body mass, Mmm, the values were similar in both sexes (8.99 ñ 1.86 m/kg lean body mass/min in women and 8.94 ñ 0.8 in men, NS). Finally, another maneuver commonly used to normalize MJ in function of metabolic size, expresing it per square meter of body surface, Ma, failed to disclose a sex-differnce (225.5 ñ 20.6 mg/m2/min in women and 263.5 ñ 52.8 in men, NS). We conclude that no sex-difference exists in M when expressed per kilogram of lean body mass, thus contradicting previous data published elsewhere