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PubMed1993

On the puzzling arrangement of the asymmetric MalT-binding sites in the MalT-dependent promoters.

The MalT-dependent promoters of the enterobacteria belong to a small family of positively regulated prokaryotic promoters in which the activator protein recognizes short asymmetric nucleotide sequences present in several locations and orientations. We demonstrate that active MalT-dependent semisynthetic promoters can be constructed by using a synthetic decanucleotide as the MalT site and random nucleotide sequences as connecting sequences, provided that the location and orientation of the sites are the same as in natural MalT-dependent promoters. Strikingly, the induced level of promoter activity and the induction factor of each semisynthetic promoter are identical to those of its natural counterpart, in spite of considerable differences in their nucleotide sequences. The study of these semisynthetic promoters confirms the importance of the structural motif formed by two MalT sites in a direct repeat. This motif is involved in promoter activation either alone or in conjunction with a third MalT site, proximal with respect to the transcription start site. In this latter configuration, the promoters are active irrespective of the orientation of the repeat, and they retain at least some activity when the distance between the repeat and the proximal site is increased, provided that the alignment along the axis of the helix is conserved.

Bacterial Proteins↗

PubMed1998

Antigen-dependent progression of mucosa-associated lymphoid tissue (MALT)-type lymphoma in the stomach. Effects of antimicrobial therapy on gastric MALT lymphoma in mice.

In humans, low-grade B-cell mucosa-associated lymphoid tissue (MALT) lymphomas of the stomach regress when Helicobacter pylori infection is cured by antimicrobial therapy. Using an animal model of human gastric MALT lymphoma, we observed the effects of Helicobacter felis eradication and the relationship between infection and disease progression. Antimicrobial therapy was given to one-half of the BALB/c mice infected with H. felis for 20 months. Groups of antibiotic-treated and untreated mice were killed 2, 3, and 4 months after antimicrobial therapy (ie, 22, 23, and 24 months after infection). The numbers of mice with MALT decreased after H. felis eradication with no lymphoid follicles seen 4 months after treatment. MALT lymphoma was present in a total of 23% (11/48) of antibiotic-treated infected mice compared with 75% (27/36) in untreated infected mice. These lymphomas were further graded into low-, intermediate-, and high-grade lymphoma. In the untreated mice, lymphoma development was more advanced with 36% low-grade (13/36), 39% intermediate-grade (14/36), and 6% high-grade (large B-cell) lymphoma (2/36) whereas in the treated mice the incidence was 21% (10/48), 6% (3/48), and 0% (0/48), respectively. These observations suggest that antigenic stimulation by H. felis sustained growth and progression of low-grade MALT lymphoma and that primary high-grade gastric lymphomas can evolve from the transformation of these tumors. Eradication of the organism caused low-grade tumors to regress, with inhibition or slowing down of lymphoma development toward high-grade lymphoma. The H. felis mouse model of gastric MALT lymphoma presents an opportunity to address the issues arising from antimicrobial treatment of these tumors in humans.

Animals↗

PubMed2004

Variable frequencies of MALT lymphoma-associated genetic aberrations in MALT lymphomas of different sites.

Although several recurrent genetic aberrations are known to occur in MALT lymphoma, no comprehensive study on the most prevalent MALT lymphoma-associated genetic aberrations is available. We therefore screened 252 primary MALT lymphomas for translocations t(11;18)(q21;q21), t(14;18)(q32;q21), and t(1;14)(p22;q32), and trisomies 3 and 18. The above-listed translocations occurred mutually exclusively and were detected overall in 13.5, 10.8, and 1.6% of the cases; trisomy 3 and/or 18 occurred in 42.1%. The frequency at which the translocations occurred varied markedly with the primary site of disease. The t(11;18)(q21;q21) was mainly detected in pulmonary and gastric tumors, whereas the t(14;18)(q32;q21) was most commonly found in lesions of the ocular adnexa/orbit, skin, and salivary glands. Trisomies 3 and 18 each occurred most frequently in intestinal and salivary gland MALT lymphomas. Our results demonstrate that the three translocations and trisomies 3 and 18 occur at markedly variable frequencies in MALT lymphoma of different sites.

Chromosome Aberrations↗

PubMedDate not supplied

Detection of polypeptides and amylase isoenzyme modifications related to malting quality during malting process of barley by two-dimensional electrophoresis and isoelectric focusing with immobilized pH gradients.

Two cultivars ("Alexis" and "Lenka") of contrasting final attenuation values were malted, and the protein and amylase isoenzyme composition, as well as the change in protein and amylase isoenzyme composition during malting, was investigated by two-dimensional polyacrylamide gel electrophoresis of total proteins, and isoelectric focusing of amylase isoenzymes, respectively. Isoelectric focusing demonstrated that significant differences exist between the amylase isoenzyme patterns of the two cultivars, suggesting a correlation between the presence of certain amylase isoenzyme bands and final attenuation. This finding was confirmed by analysis of 36 barley cultivars with a wide range of quality. It was shown that all cultivars which are of low or, at best, moderate final attenuation values exhibit the amylase band "B" (isoelectric point approximately 6.8), whereas those cultivars which are predominantly of high malting grade do not possess this "B" isoenzyme band, but exhibit the pronounced "A" isoenzyme band (isoelectric point approximately 6.5) instead, suggesting that these isoenzymes (which we suppose to be beta-amylases) can be utilized to predict the final attenuation values of unknown barley samples or new lines. However, "final attenuation" is a complex function. Preliminary results of two-dimensional gel electrophoresis indicate that other factors, such as total amount of amylases, or a 19 kDa A hordein-like polypeptide, which was degraded faster in the low malting grade cultivar "Lenka", may also have a role in determining quality.

Amylases↗

PubMed1970

Fecal streptococci on barley and malt kernels and instant malted milk powder.

Among 500 barley kernels, tested singly, 1.8% (9 kernels) were positive for fecal streptococci. Among 800 malt kernels, tested singly by the same procedure, 68% (540 kernels) were positive for fecal streptococci. In unsulfured and sulfured malts, 67 and 68% of the kernels, respectively, were positive for these bacteria. Fecal streptococci were also isolated by an enrichment procedure from two brands of instant malted milk powder sold in supermarkets. Seventy randomly picked isolates from malts were identified to be fecal streptococci, belonging probably to more than one species.

Agar↗

PubMed1999

What are the criteria for distinguishing MALT from non-MALT lymphoma at extranodal sites?

Criteria for the diagnosis of low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type differed among participants in the Society for Hematopathology Workshop. Some would accept any extranodal lymphoma that lacked features of another lymphoma type as MALT type, while others required the presence of all morphologic criteria. Criteria for the diagnosis of MALT-type lymphoma can be clinical, morphologic, and biologic, and the implications of making the diagnosis may dictate how restrictive the criteria for diagnosis should be. The morphologic definition of MALT lymphoma is a lymphoma that recapitulates the structure of the Peyer's patch. The clinical definition is an indolent extranodal lymphoma that tends to remain localized or to recur in other extranodal sites, with a potential for cure with local therapy. The biologic definition is unknown, but it includes an antigen-stimulated B cell with a special relationship to epithelial tissues and germinal centers. For clinical purposes, exclusion of one of the other types of small B-cell lymphoma may be sufficient to dictate treatment. For investigation and further understanding of lymphomas, however, a more restrictive definition should be used, since there may be other small B-cell lymphomas not yet described.

Diagnosis, Differential↗

PubMed1999

Primary low-grade gastric mucosa-associated lymphoid tissue (MALT) lymphoma with polypoid appearance. Polypoid gastric MALT lymphoma: A clinicopathologic study of eight cases.

In the current study, we report eight cases with primary low-grade gastric mucosa-associated lymphoid tissue (MALT) lymphoma endoscopically characterized by polypoid lesions in order to highlight their clinicopathologic significance. Four patients were male, their ages ranging from 40 to 78 years old. The resected specimens revealed a histology of low-grade MALT lymphoma characterized by dense lymphocytic infiltration predominantly in the submucosa and a relatively monotonous proliferation of centrocyte-like cells with reactive follicles and infrequent lymphoepithelial lesions. The tumor cells were of CD5-, CD10-, CD20+, BCL2+ and cycline D1- phenotype, and showed a monoclonal rearrangement of immunoglobulin heavy chain genes in the five of six cases examined. Interestingly, Helicobacter pylori (H. pylori) was detected in three (37.5%) of the eight patients, which was significantly lower than previous reports. Two of the H. pylori-positive cases initially underwent H. pylori eradication, but showed no change in their lymphomas after the cure of H. pylori infection. The clinicopathologic findings of the present cases appeared to closely resemble those of colorectal MALT lymphoma with a polypoid appearance and few association of H. pylori infection in their pathogenesis. These gastric polypoid cases may merit separate consideration because of the therapeutic problems they pose.

Adult↗

PubMed2002

Effectiveness of local radiotherapy in primary extranodal marginal zone B-cell lymphoma of MALT or MALT lymphoma of conjunctiva: study of four cases.

Primary lymphomas of the conjunctiva are extremely infrequent and usually belong to extranodal marginal zone B-cell lymphoma of MALT or MALT lymphoma. Radiotherapy with lens shielding is one of the most employed therapeutic options. Four patients with MALT lymphomas of the conjunctiva with complete and maintained response to radiotherapy are reported. The effectiveness as well as the lack of significant toxicity of radiotherapy are emphasized.

Adolescent↗

PubMed1991

Effect of chemical treatments on the micro-organisms associated with malting of sorghum grains and sorghum malt.

The effect of five chemical preservatives on the micro-organisms associated with sorghum grain and malts was investigated. Sorbic acid, sodium benzoate, nisin, formaldehyde and lime at concentrations up to 500, 100, 1000, 1500 and 2000 ppm, respectively did not adversely affect the malting properties of sorghum grain. Only HCHO and Ca(OH)2, each of which prevented bacteria and mould growth at 500 and 2000 ppm, respectively, were sufficiently effective at maximum practicable concentrations to control microbial contamination during malting.

Bacteria↗

PubMed2001

Characterization of lactobacilli from Scotch malt whisky distilleries and description of Lactobacillus ferintoshensis sp. nov., a new species isolated from malt whisky fermentations.

Sixty-four strains of Lactobacillus were isolated from fermentation samples from 23 malt whisky distilleries located in the major whisky producing regions of Scotland. The strains were assigned to 26 ribotype patterns. Strains of some ribotype patterns were widely distributed and recovered from distilleries throughout Scotland, while strains representing other ribotypes were particular to a specific region or even a certain distillery. Repeated sampling of a single distillery over a 12 month period showed that the range of bacteria present, as indicated by ribotyping, was stable, but was influenced by changes in malt supply and the period of closure for annual maintenance. Partial 16S rDNA sequence analysis of ribotype representatives revealed Lactobacillus brevis, Lactobacillus fermentum, Lactobacillus paracasei and Lactobacillus pentosus as the major species present in the distilleries; however, four isolates could not be identified by this procedure. Determination of the full 16S rDNA gene sequence from one of these isolates (strain R7-84) revealed >98.5% similarity to Lactobacillus buchneri and its phylogenetic neighbours. DNA from two other strains showed greater than 70% hybridization to DNA from R7-84 under non-stringent renaturation conditions and DNA from strain R7-84 shared less than 65% hybridization with members of the L. buchneri group. It is proposed that these three strains should be placed in a new species for which the name Lactobacillus ferintoshensis represented by the type strain R7-84(T) is suggested.

Alcoholic Beverages↗

PubMed1966