Altered expression of glycosaminoglycans in metastatic 13762NF rat mamma adenocarcinoma cells

A difference in the expression and metabolism of sulfated glycosaminoglycans between rat mammary tumor cells derived from a primary tumor and those from its metastatic lesions has been observed. Cells from the primary tumor possessed about equal quantities of chondroitin sulfate and heparan sulfate on their cell surfaces but released fourfold more chondroitin sulfate than heparan sulfate into their medium. In contrast, cells from distal metastatic lesions expressed approximately 5 times more heparan sulfate than chondroitin sulfate in both medium and cell surface fractions. This was observed to be the result of differential synthesis of the glycosaminoglycans and not of major structural alterations of the individual glycosaminoglycans. The degree of sulfation and size of heparan sulfate were similar for all cells examined. However, chondroitin sulfate, observed to be only chondroitin 4-sulfate, from the metastases-derived cells had a smaller average molecular weight on gel filtration chromatography and showed a decreased quantity of sulfated disaccharides upon degradation with chondroitin ABC lyase compared to the primary tumor derived cells. Major qualitative or quantitative alterations were not observed for hyaluronic acid among the various 13762NF cells. The metabolism of newly synthesized sulfated glycosaminoglycans was also different between cells from primary tumor and metastases. Cells from the primary tumor continued to accumulate glycosaminoglycans in their medium over a 72-h period, while the accumulation of sulfated glycosaminoglycans in the medium of metastases-derived cells showed a plateau after 18-24 h. A pulse-chase kinetics study demonstrated that both heparan sulfate and chondroitin sulfate were degraded by the metastases-derived cells, whereas the primary tumor derived cells degraded only heparan sulfate and degraded it at a slower rate.(ABSTRACT TRUNCATED AT 250 WORDS)     

Randomised controlled trial of short term treatment to eradicate Helicobacter pylori in patients with duodenal ulcer.

OBJECTIVE--To determine whether one week''s drug treatment is sufficient to eradicate Helicobacter pylori in patients with duodenal ulcer. DESIGN--Single blind, randomised controlled trial. SETTING--Specialised ulcer clinic in a teaching hospital. PATIENTS--155 patients with H pylori and a duodenal ulcer verified endoscopically which had either bled within the previous 24 hours or was causing dyspepsia. INTERVENTIONS--Patients were allocated randomly to receive either omeprazole for four weeks plus bismuth 120 mg, tetracycline 500 mg, and metronidazole 400 mg (all four times a day) for the first week (n = 78), or omeprazole alone for four weeks (n = 77). Further endoscopy was performed four weeks after cessation of all drugs. MAIN OUTCOME MEASURES--Presence or absence of H pylori (by urease testing, microscopy, and culture of antral biopsy specimens), duodenal ulcer, and side effects. RESULTS--Eradication of H pylori occurred in 70 (95%) patients taking the four drugs (95% confidence interval 86% to 97%) compared with three (4%) patients taking omeprazole alone (1% to 11%). Duodenal ulcers were found in four (5%) patients taking the four drugs (2% to 12%) and in 16 (22%) patients taking omeprazole alone (14% to 32%). Mild dizziness was the only reported side effect (six patients in each group) and did not affect compliance. CONCLUSIONS--A one week regimen of bismuth, tetracycline, and metronidazole is safe and effective in eradicating H pylori and reduces the number of duodenal ulcers four weeks after completing treatment.     

Expression of epidermal growth factor receptor and associated glycoprotein on cultured human brain tumor cells

The expression of epidermal growth factor (EGF-R) in normal glial and glioma cells grown in culture was examined by using several independent assays. Immunoprecipitation with the monoclonal antibody R1 of extracts from metabolically labeled glial and glioma cells revealed a protein of Mr approximately 170,000, with a migration in sodium dodecyl sulfate-polyacrylamide gels identical to the EGR-R of A431 epidermal carcinoma cells. Furthermore, in the majority of glioma extracts, a protein of Mr approximately 190,000 was specifically immunoprecipitated by this antibody. Similar results were obtained by immunoblotting with a second antibody directed against a synthetic peptide in the sequence of the v-erb-B oncogene. In cell lines expressing both proteins, each was specifically phosphorylated on tyrosine in immune complex kinase assays. The majority of glioma cells bound between 40,000 to 80,000 125I-labeled epidermal growth factor molecules per cell. These results suggest that the expression of EGF-R is common in cultured human glioma cells. In addition, a structurally related protein, is expressed in some of these cells.     

The dnaA initiator protein binds separate domains in the replication origin of Escherichia coli

After binding to its four 9-mer boxes in the 245-base pair Escherichia coli replication origin (oriC), dnaA protein effects the formation of an "open complex" in an adjacent region made up of three 13-mers (Bramhill, D., and Kornberg, A. (1988) Cell 52, 743-755). This open complex formation requires the ATP form of dnaA protein assisted by HU protein (Sekimizu, K., Bramhill, D., and Kornberg, A. (1987) Cell 50, 259-265). We now provide direct evidence that dnaA protein binds the 13-mers, sequences that bear no resemblance to the 9-mer box. The evidence is (i) displacement of dnaA protein from the open complex by oriC or by a synthetic oligonucleotide containing the 13-mers, but not by a mutant of oriC lacking the 13-mers; (ii) filter binding of the synthetic (13-mer) oligonucleotide by dnaA protein; and (iii) requirement for the ATP form of dnaA protein assisted by HU protein for temperature-dependent binding to the 13-mer region. Controlled proteolysis of dnaA protein results in a prompt loss of oriC binding; an NH2-terminal 30-kDa peptide contains the domain that binds ATP and phospholipids known to destabilize the tightly bound ATP.     

A major difference between the divergence patterns within the lines-1 families in mice and voles

L1 retroposons are represented in mice by subfamilies of interspersed sequences of varied abundance. Previous analyses have indicated that subfamilies are generated by duplicative transposition of a small number of members of the L1 family, the progeny of which then become a major component of the murine L1 population, and are not due to any active processes generating homology within preexisting groups of elements in a particular species. In mice, more than a third of the L1 elements belong to a clade that became active approximately 5 Mya and whose elements are > or = 95% identical. We have collected sequence information from 13 L1 elements isolated from two species of voles (Rodentia: Microtinae: Microtus and Arvicola) and have found that divergence within the vole L1 population is quite different from that in mice, in that there is no abundant subfamily of homologous elements. Individual L1 elements from voles are very divergent from one another and belong to a clade that began a period of elevated duplicative transposition approximately 13 Mya. Sequence analyses of portions of these divergent L1 elements (approximately 250 bp each) gave no evidence for concerted evolution having acted on the vole L1 elements since the split of the two vole lineages approximately 3.5 Mya; that is, the observed interspecific divergence (6.7%-24.7%) is not larger than the intraspecific divergence (7.9%-27.2%), and phylogenetic analyses showed no clustering into Arvicola and Microtus clades.      

Monitoring trichloroethylene mineralization by Pseudomonas cepacia G4 PR1

To analyze the extent of mineralization of trichloroethylene (TCE) without disturbing an actively growing biofilm, a minimal growth medium was formulated that reduces the concentration of chloride ions to the extent that the chloride ions generated from TCE mineralization may be detected with a chloride-ion-specific electrode. By substituting chloride salts with phosphates and nitrates, a chloride-free minimal medium was produced that yields a specific growth rate for Pseudomonas cepacia G4 PR1 which was 93% of that in chloride-ion-containing minimal medium. Furthermore, TCE degradation by resting cell suspensions was similar in both media (85% of 75 M TCE degraded in 6 h), and complete mineralization of TCE was slightly superior in the chloride-free minimal medium (77% compared to 60% of 75 M TCE mineralized in 6 h). In addition, indole-containing, minimal-medium agar plates were developed to indicate the presence of the TCE-degrading enzyme toluene ortho-monooxygenase (fire-engine-red colonies) as well as to distinguish this enzyme from other TCE-degrading enzymes (toluene dioxygenase and toluene para-monooxygenase).