CD304 is preferentially expressed on a subset of B-lineage acute lymphoblastic leukemia and represents a novel marker for minimal residual disease detection by flow cytometry

Minimal residual disease (MRD) has emerged as a major prognostic factor for monitoring patients with B-lineage acute lymphoblastic leukemia (B-ALL). The quantification of MRD by flow cytometry (FC) is based on the identification of a leukemia-associated phenotype (LAP). Because phenotypic switch is common during treatment, multiple LAPs must be available and used for MRD detection over time. We evaluated the potential usefulness of CD304 as a new marker for monitoring MRD. CD304 was expressed in 48% of B-ALL (24/50) with discriminative fluorescence intensity compared with CD304-negative normal B-cell precursors (n = 15). The sensitivity of CD304-based MRD detection reached 10(-4), as with some of established LAPs. The stability of CD304 expression evaluated during therapy and at relapse confirms the usefulness of this marker for MRD quantification. Finally, CD304 was repeatedly expressed in patients with TEL-AML1 gene rearrangement, which warrants further investigation on its potential relevance as a prognosis marker or therapeutic target.     

Combined Effect of Bacteriocins on the Survival of Various Listeria Species in Broth and Meat System

The antilisterial efficiency of three bacteriocins from lactic acid bacteria, lactocin 705 (produced by L. casei CRL705, 17000 AU/ml), enterocin CRL35 (produced by E. faecium CRL35, 17000 AU/ml), and nisin (2000 IU/ml), was tested in broth, individually and in combination against Listeria monocytogenes and Listeria innocua. Both Listeria species showed an initial decrease in viable counts followed by the regrowth of the survivors after 1 h in the presence of each bacteriocin. A greater antilisterial effect was observed when the bacteriocins were combined in pairs, maximal inhibition being reached when nisin was involved. When a mix of the three bacteriocins was used, no survivors were observed after 24 h of incubation. Similar results were obtained when the bacteriocin combinations were tested in a meat system, indicating that the use of more than one LAB bacteriocin in combination may be effective in preventing the spontaneous emergence of a bacteriocin-resistant Listeria population. Received: 17 March 2000 / Accepted: 26 June 2000     

Characterization of Leuconostoc gasicomitatum sp. nov., associated with spoiled raw tomato-marinated broiler meat strips packaged under modified-atmosphere conditions

Lactic acid bacteria (LAB) associated with gaseous spoilage of modified-atmosphere-packaged, raw, tomato-marinated broiler meat strips were identified on the basis of a restriction fragment length polymorphism (RFLP) (ribotyping) database containing DNAs coding for 16S and 23S rRNAs (rDNAs). A mixed LAB population dominated by a Leuconostoc species resembling Leuconostoc gelidum caused the spoilage of the product. Lactobacillus sakei, Lactobacillus curvatus, and a gram-positive rod phenotypically similar to heterofermentative Lactobacillus species were the other main organisms detected. An increase in pH together with the extreme bulging of packages suggested a rare LAB spoilage type called "protein swell." This spoilage is characterized by excessive production of gas due to amino acid decarboxylation, and the rise in pH is attributed to the subsequent deamination of amino acids. Protein swell has not previously been associated with any kind of meat product. A polyphasic approach, including classical phenotyping, whole-cell protein electrophoresis, 16 and 23S rDNA RFLP, 16S rDNA sequence analysis, and DNA-DNA reassociation analysis, was used for the identification of the dominant Leuconostoc species. In addition to the RFLP analysis, phenotyping, whole-cell protein analysis, and 16S rDNA sequence homology indicated that L. gelidum was most similar to the spoilage-associated species. The two spoilage strains studied possessed 98.8 and 99.0% 16S rDNA sequence homology with the L. gelidum type strain. DNA-DNA reassociation, however, clearly distinguished the two species. The same strains showed only 22 and 34% hybridization with the L. gelidum type strain. These results warrant a separate species status, and we propose the name Leuconostoc gasicomitatum sp. nov. for this spoilage-associated Leuconostoc species.     

Use of Group-Specific and RAPD-PCR Analyses for Rapid Differentiation of <Emphasis Type="Italic">Lactobacillus</Emphasis> Strains from Probiotic Yogurts

The increasing interest in probiotic lactobacilli implicates the requirement of techniques that allow a rapid and reliable identification of these organisms. In this study, group-specific PCR and RAPD-PCR analyses were used to identify strains of the Lactobacillus casei and Lactobacillus acidophilus groups most commonly used in probiotic yogurts. Group-specific PCR with primers for the L. casei and L. acidophilus groups, as well as L. gasseri/johnsonii, could differentiate between 20 Lactobacillus strains isolated from probiotic yogurts and assign these into the corresponding groups. For identification of these strains to species or strain level, RAPD profiles of the 20 Lactobacillus strains were compared with 11 reference strains of the L. acidophilus and L. casei group. All except one strain could be attributed unambigously to the species L. acidophilus, L. johnsonii, L. crispatus, L. casei, and L. paracasei. DNA reassociation analysis confirmed the classification resulting from the RAPD-PCR.     

Pharmacological profile of a novel carbacyclin derivative with high metabolic stability and oral activity in the rat

A novel carbacyclin derivative (16S)-13,14-dehydro-16,20-dimethyl-3-oxa-18,18,19,19-tetradehydro-6a-carbaprostaglandin-I₂ (3-oxa-analogue) has been synthesized in order to find chemically and metabolically stable prostacyclin-memetics with a potency equal or even superior to PGI₂.The 3-oxa-analogue was found to be stabilized against β-oxidation, a main metabolic degradation step also for chemically stable PGI₂-analogues. The compound is orally available and displays a long duration of 4,5 – 48 h of antiaggregatory and hypotensive action. The 3-oxa-analogue inhibits ADP-induced platelet aggregation with an IC₅₀ of 3.0 nM. Following intravenous application the 3-oxa-analogue lowers diastolic blood pressure in a dose dependent manner, the ED₂₀ being 0.1 – 0.2 μg/kg after injection and ≤ 0.05 μg/kg/min after infusion respectively. In vivo platelet aggregation is inhibited after i.v. infusion of the 3-oxa-analogue with an IC₅₀ of 0.037 μg/kg/min. As compared to Iloprost, the 3-oxa-analogue is 5 – 12 fold more potent with respect to in vivo hypotensive and anti-aggregatory effects.The results of the present studies indicate that the 3-oxa-analogue has a pharmacological profile comparable to prostacyclin (PGI₂) and Iloprost. Due to the fact that the 3-oxa-analogue is chemically and metabolically stable, long term oral treatment can be achieved in clinical conditions in which PGI₂ and Iloprost have already been shown to be therapeutically useful principles.     

Stable 9 beta- or 11 alpha-halogen-15-cyclohexyl-prostaglandins with high affinity to the PGD2-receptor

Various chemically stable prostaglandin analogues were studied for their affinity towards the PGD2-receptor in human platelet membranes in order to define the requirements for specific ligand binding to this receptor. On replacing the 11- or 9-hydroxyl groups of PGF2 alpha by an 11 alpha- or 9 beta-chloro- or fluoro atom, stable prostaglandin analogues were obtained, which showed high affinity towards the PGD2-receptor. The lower side chain consisted of a 15-cyclohexyl group or of the natural 15-n-pentyl group, other substitutents decreased the affinity substantially. The highest PGD2-mimetic activity with a relative affinity of 0.5 to the PGD2-receptor was found in 9-deoxy-9 beta-chloro-16,17,18,19,20-pentanor-15-cyclohexyl-PGF2 alpha (ZK 110 841, compound 16 in Table 1). ZK 110 841 is a chemically stable crystalline substance, which is orally active and which might thus turn out to be an interesting tool for the study of PGD2-receptor interactions. Some other prostaglandin as well as prostacyclin analogues with a 15-cyclohexyl or 15-n-pentyl group exhibited in addition to their known high affinity to the PGE2-receptor of human uterine membranes or the PGI2-receptor of human platelets also affinities to the PGD2-receptor. Generally, the receptor affinities correlate with the activities as stimulators of adenylate cyclase and inhibitors of thrombin induced elevation of cytoplasmic free calcium as well as their ability to inhibit ADP-induced platelet aggregation. The PGI2-character regarding the effector systems prevails in compounds with affinity to both the PGI2- and PGD2-receptor. Compounds which bind to the PGE2- and PGD2-receptor show a flat dose response curve regarding platelet activation suggesting a mixture of pro- and antiaggregatory properties within these molecules.     

New methods to assess bacterial injury in water.

Two methods are described for measurement of bacterial injury in water. Laboratory time preceding cell division measured with slide cultures and spheroplast formation after lysozyme treatment were accurate and rapid measurements of bacterial damage.     

Variable methylation and differential replication of genomic DNA in cultured carrot root expiants during growth induction as influenced by hormonal treatments

Summary The methylation and amplification pattern of genomic DNA of carrot root expiants (Daucus carota L.) undergoes transitory changes during the cultural cycle. A high degree of variation was observed as early as 36 h after the incubation of fresh expiants in the nutrient medium and, depending on the hormonal treatment significant modifications occurred during 14 days of culture. Proliferative tissue conditioned by kinetin showed an extensive reduction in DNA methylation. Changes in the DNA amplification pattern were not necessarily linked to methylation.