Considerations on the possible origins of fetal hemoglobin cells produced in developing tumors.

Although tumor angiogenesis in relation to cancer therapy has been widely investigated for more than four decades, its counterpart tumor hematopoiesis has not been equally considered. In that respect, in our long-term immunohistochemical examination of fetal hemoglobin (HbF) cells in various solid tumors, we have observed signs of fetal hematopoiesis in situ within the tumors. We hypothesize that this observed fetal hematopoiesis, involving angiogenesis, mirrors mammalian blood system development in the embryo and the fetus; this is consistent with the concept of the hemogenic endothelial progenitor, common to endothelial and hemopoietic cells. Based on this assumption, there should exist in tumors at least two routes of hematoangiogenesis: one of fetal (HbF) hematopoiesis and the other of adult (HbA) hematopoiesis, each one deserving a different therapeutic approach. In the fetal route, HbF should support tumor growth by virtue of its high oxygen affinity.

Integron-mediated ESBL resistance in rare serotypes of Escherichia coli causing infections in an elderly population of Israel.

OBJECTIVES: To identify and characterize the aetiology of an outbreak of extra-intestinal multidrug-resistant Escherichia coli infections in elderly patients in Israel. METHODS: Extended-spectrum beta-lactamase (ESBL)-producing clinical isolates of E. coli from extra-intestinal sources were tested for susceptibility to non-beta-lactam drugs, and their serotypes were determined. Restriction enzyme digestion, followed by PFGE of DNA purified from isolates, was used to classify the phylogenetic relationship between them. Plasmid DNA from five isolates of different serotypes was used to transform an E. coli laboratory strain. The plasmids were partially sequenced. RESULTS: E. coli isolates from 86 patients, mostly elderly, were shown to be positive for inhibitor-susceptible ESBLs, and more resistant to cefotaxime than to ceftazidime. Ninety-six per cent of ESBL producers were also resistant to gentamicin, and 100% to trimethoprim/sulfamethoxazole and ciprofloxacin. All isolates belonged to one of five serotypes. PFGE analysis of purified DNA yielded 17 profiles. Sequencing of plasmids isolated from the transformants identified sul1, aac(6')-Ib and bla(CTX-M-2). These genes were embedded in an integron, InS21. CONCLUSIONS: Extra-intestinal infections with ESBL-producing E. coli of different serotypes and probably mixed clonality showed a surprising homogeneity in resistance profiles, with 100% being co-resistant to ciprofloxacin and trimethoprim/sulfamethoxazole, and 96% to gentamicin. Plasmid DNA from three isolates from different serotypes contained integron InS21, previously demonstrated in Salmonella enterica from Argentina. This is the first molecular identification of an ESBL gene and integron in Israel or neighbouring geographical areas.

Endemic occurrence of infections by multidrug-resistant Escherichia coli of four unique serotypes in the elderly population of Israel.

During a period of four years, multidrug-resistant Escherichia coli of particular serotypes have been isolated from 255 elderly (>65 years) patients from four hospitals in central Israel. 83% of the isolates belonged to one of four predominant serotypes (O153:H31, O101:H-, O2:H42, and O102:H6). All isolates were producers of extended spectrum beta-lactamases and resistant to ciprofloxacin. To our knowledge, the involved serotypes have hitherto not been reported as etiological agents of extraintestinal human infections (MEDLINE). Pulsed-field gel electrophoresis of isolates from one of the most frequent serotypes indicated a clonal relationship between them. Further investigation of these strains and analysis of their virulence factors may help to confine their spread.

Enteroaggregative Escherichia coli serotype O126:H27, Israel.

Enteroaggregative Escherichia coli (EAEC) is a newly diarrheagenic agent wherein several predominant serotypes are reported. We studied the association between those serotypes, as clonal indicators, and the trait of enteroaggregative adherence to host cells, tested by polymerase chain reaction. We also evaluated the clinical manifestations of infection in 17 hospitalized children by our most common EAEC serotype, O126:H27.

The inducing capacities of the primary hypoblast as revealed by transfilter induction studies.

1. The inducing powers of the primary hypoblast of the chick embryo were studied by the insertion of a TH millipore filter between the hypoblast and the reacting epiblast. 2. Two successive inducing capacities were discovered in the hypoblast. The first to appear and disappear is the inductor of the primitive streak, while the second is a prosencephalic inductor. 3. The formation of a mature primitive streak which contains a Hensen's node is dependent on direct cellular contact between the epiblast and hypoblast, and most probably on the inclusion of hypoblastic cells in the forming node and notochord. 4. The formation of spinal cord-like structures and undifferentiated neural plates can be related to the presence of nodeless primitive streaks in the blastoderms. These neural structures are probably induced by the mesoderm produced by the defective primitive streaks, which were unable to form notochord or somites. 5. The primary hypoblast, by virtue of its prosencephalic inducing power, can be compared with the presumptive pharyngeal endoderm of the amphibian embryo.