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PubMed1982

A DNA sequence containing the control sites for gene malT and for the malPQ operon.

The order of 802 base pairs was established in a DNA segment containing the promoter for malPQ which is one of the three maltose operons, and the promoter for malT, the positive regulator gene of the maltose regulon. The determination of the amino-terminal sequence of the MalT protein allowed us to identify the beginning of the malT gene on the sequence. The position of the malP gene was deduced from the published amino-terminal sequence of maltodextrin phosphorylase. A total of 611 base pairs separate the initiation codons for these two genes, which are transcribed in opposite directions. This large intergenic region does not code for any polypeptide of significant size. The main features of this sequence are discussed in terms of the regulation known to operate on malT and malPQ expression.

Bacterial Proteins↗

PubMed1980

Mutants which make more malT product, the activator of the maltose regulon in Escherichia coli.

Some of the previously described malT-lacZ fusion strains (Débarbouillé and Schwartz, 1979) produce very low amounts of beta-galactosidase activity and hence grow poorly on lactose. Spontaneous mutants growing faster on lactose have been isolated. Some of the mutations map in, or close to, the promoter of the hybrid gene. They lead to an increased production of the hybrid proteins, which then become detectable on polyacrylamide gels. This effect is cis dominant. When the mutations, called malTq, are transduced into a malT+ background the resulting transductants express the three maltose operons in a partially constitutive way. The malTq mutations therefore represent a new type of constitutive mutation. Their existence provides further evidence for the previously proposed model of positive regulation in the maltose regulon. In addition they should facilitate the purification of the malT product, and the identification of the malT promoter on the DNA.

Escherichia coli↗

PubMed1997

Diagnosis of MALT lymphoma by conjunctival biopsy: a case report.

BACKGROUND: Most extranodular lymphatic tissue is found in the intestinal mucosa. Together with similarly structured lymphatic tissue at other locations it has been named mucosa-associated lymphatic tissue (MALT). Malignant transformation of such tissue to lymphoma is well known. Although MALT lymphoma has been described in tissue physiologically void of MALT, lymphoma manifestation in the conjunctiva is rare. METHODS: We report a case of a 47-year-old woman who was referred to our clinic for symptomatic treatment and evaluation of severe symptoms of dry eyes. She was thought to suffer from Sjögren's syndrome because of xerophthalmia and xerostomia, as well as massive bilateral swelling of the parotid gland. Ophthalmological examination revealed marked hyperplasia of the conjunctiva, of which a biopsy was taken. RESULTS: Histological and immunohistochemical examination of the conjunctival biopsy, together with analysis of gene rearrangement by Southern blot, led to the diagnosis of low-grade B-cell lymphoma of the MALT. CONCLUSION: The differential diagnosis of keratoconjunctivitis sicca presenting with conjunctival swelling of unknown origin should include lymphoma, especially since Sjögren's syndrome may be associated with malignant disorders of the lymphatic system. A biopsy of suspicious conjunctival changes can clarify a multisystem disease by providing a tissue diagnosis.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1989

Mineral utilization of malted sorghum and corn with added crayfish in rats.

Forty adult rats were used to study the mineral balances of malted and unmalted wet- or dry-milled sorghum and corn combined with crayfish and fed rats for 12 days. Five out of the twelve days were for adjustment and the rest for balance period. These mixtures each was calculated to provide 1.6 g N daily for the entire study period. Malting and wet milling produced increases in crude protein content of the cereal grains. However, the increases were much more evident in sorghum. Wet milling caused increases in calcium retention in corn groups. It produced the same effect on phosphorus balance only in sorghum groups. On the other hand, it produced positive iron balances only in unmalted corn and malted sorghum groups. The results suggest improved mineral nutriture due to malting except for the Fe retention of the MDC:CR group.

Animal Nutritional Physiological Phenomena↗

PubMed1995

Mantle cell lymphoma with the features of mucosa-associated lymphoid tissue (MALT) lymphoma in an HTLV-I-seropositive patient.

A case of small lymphocytic B-cell lymphoma with seropositivity for human T-cell leukemia virus type I (HTLV-I), whose clinical features were closely related to those of mucosa-associated lymphoid tissue (MALT) lymphoma, is presented. The neoplastic cells of the lymph node were immunologically positive for CD5, in addition to several B-cell markers, but negative for CD10, and cytogenetically carried a t(11;14)(q13;q32). These findings were fully consistent with so-called mantle cell lymphoma (MCL). In addition to the lymph nodes and bone marrow, multiple extranodal sites including lacrimal and salivary glands, lung and stomach (where MALT is present) were occupied by lymphoma cells. These extranodal lesions were immunologically identical to the lymph nodes (CD5(+), CD10(-)), but histologically showed lymphoepithelial lesions (LEL) characteristic of MALT lymphoma. These findings suggest a possible relationship between MCL and MALT lymphoma, and the neoplastic cells are thought to originate from the CD5-positive B cells, which are present near the areas across the mantle and marginal zones. Furthermore, HTLV-I-infection, which appears to create an immunodeficient state or modulate the B-cell response, is thought to play a role in B-cell lymphomagenesis.

Antigens, CD↗

PubMed2001

[Impaired CD95-(Fas,APO-1-)apoptosis regulation is a progression factor in early MALT-type lymphoma genesis].

BACKGROUND: MALT-type lymphomas are B cell tumors arising for so far unknown reasons on the background of chronic inflammation, e.g. Helicobacter pylori-associated gastritis. T cells are supposed to have a positive impact on tumor growth, but fail in their control function. We therefore examined the interaction of T cells with malignant B cells in vitro and focused on T cell control which normally operates by CD95L/CD95-mediated apoptosis. PATIENTS AND METHODS: Malignant B cells were isolated from tumor tissues of 7 patients with low-grade MALT-type lymphoma and 4 patients with DLBL and cocultured in vitro with activated T cells. Normal memory B cells were used as control. We developed a T/B coculture assay for investigation of CD95L/CD95-mediated apoptosis. The influence of T cells on CD95 expression and survival of B cells was measured by FACS analysis. RESULTS: Activated T cells induced CD95 expression and thus enhanced sensitivity to CD95L-mediated apoptosis in normal memory B cells. However, malignant B cells from 3 out of 7 low-grade MALT-type lymphomas and all 4 gastric DLBLs resisted apoptosis, although the cells showed enhanced CD95 expression. CONCLUSION: Resistance to CD95L/CD95-mediated apoptosis allows malignant B cells from MALT-type lymphoma to escape T cell control and leads to prolonged survival. This phenomenon acts as a progression factor in early lymphomagenesis.

Adult↗

PubMed2002

Markers polymorphic among malting barley ( Hordeum vulgare L.) cultivars of a narrow gene pool associated with key QTLs.

Barley used for malting is a fine-tuned organism, and it requires breeding within narrow gene pools for realistic cultivar enhancement. Significant phenotypic advance within such narrow gene pools has been achieved and the necessary genetic variability for breeding progress has been documented, but it was not well understood. This study was conducted to further characterize detectable genetic variability present within a select set of four closely related malting barley cultivars using three types of molecular markers: RFLP, PCR-RAPD and AFLP. The markers that identified polymorphism among the select malting cultivars tended to link with each other and to map in chromosomal regions associated with quantitative trait loci (QTLs) for agronomic and malting quality traits that differed among the four cultivars. Although RFLPs identified the least amount of polymorphism, the differences detected by the RFLPs best fit the chronology of the cultivars. These results indicate that a large amount of the genetic variability necessary for cultivar improvement may have originally been present in the breeding gene pool, but does not rule out de novo variation. Study of the populations from crosses within this narrow germplasm is needed to further elucidate the basis of the phenotypic variability found among these select barley cultivars.

Journal Article↗

PubMed2002

Complete remission of chronic plaque psoriasis and gastric marginal zone B-cell lymphoma of MALT type after treatment with 2-chlorodeoxyadenosine.

A 58-year-old woman with a 15-year history of chronic plaque psoriasis was diagnosed with gastric marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type. Topical treatment and ultraviolet radiation for therapy of psoriasis had been of limited efficacy. The patient received intravenous treatment with 0.12 mg/kg per day of 2-chlorodeoxyadenosine (2-CDA) over 5 days for management of MALT lymphoma, as it was resistant to eradication of Helicobacter pylori. A total of six cycles were administered from June 1999 until November 1999 (cumulative dose 244.8 mg 2-CDA). After 2 months of 2-CDA administration, psoriatic skin lesions improved significantly, and after 3 months, complete remission of skin lesions was observed. Ongoing complete remission of the MALT lymphoma could be achieved after six cycles of 2-CDA administration. After a follow-up period of 34 months, no recurrence of psoriatic lesions has occurred. The patient is at present free of psoriatic plaques and gastric MALT lymphoma. The course of disease in our patient provides evidence for sustained therapeutic efficacy of 2-CDA in chronic plaque psoriasis in the absence of severe side effects except asymptomatic lymphopenia.

Antineoplastic Agents↗

PubMed2003

Clonal relationship in multifocal non-Hodgkin's lymphoma of mucosa-associated lymphoid tissue (MALT).

To elucidate the progression of gastric marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type, we analyzed a case presenting simultaneously with MALT lymphoma of the stomach and lung, and a gastric high-grade diffuse large lymphoma. The rearranged immunoglobulin heavy chain (IgH) variable regions were analyzed using a polymerase chain reaction (PCR)-based assay. Clonal relationship was shown between the gastric high-grade and the pulmonary low-grade lymphoma. The gastric MALT lymphoma was not related to the other manifestations. Translocation t(11;18) was not detected in the gastric high-grade lymphoma. MALT lymphomas at various locations and with different histologies may derive from a common precursor cell. Lymphomas at identical sites may have different stem cells.

Aged↗

PubMed1999

CT appearances of mucosa-associated lymphoid tissue (MALT) lymphoma.

Mucosa-associated lymphoid tissue (MALT) lymphoma is a low-grade lymphoma that differs from high-grade non-Hodgkin lymphoma both clinically and histologically. The CT appearances of MALT lymphoma are described. Of 40 patients referred with biopsy-proven MALT lymphoma, only seven had not had gastrectomy or chemotherapy prior to CT examination. The CT scans of these seven cases were analysed for the degree and extent of gastric wall thickening, enlargement of abdominal and extra-abdominal lymph nodes, and presence of extra-nodal disease. In all patients the stomach was distended with oral contrast medium and scans performed at narrow collimation, after intravenous administration of 20 mg hyoscine butylbromide. In six patients focal thickening of the gastric wall was 1 cm or less. One patient had thickening of over 4 cm. There was no enlargement of abdominal or extra-abdominal lymph nodes or extension to adjacent organs. Thus on CT, at presentation, MALT lymphoma results in minimal gastric wall thickening, unlike high-grade non-Hodgkin lymphoma, which typically causes bulky gastric disease, nodal enlargement and extension into adjacent organs. CT is therefore of limited value in monitoring response to treatment. With disease greater than minimal thickening, transformation to a higher grade should be considered.

Adult↗

PubMed2002

High incidence of B-cell monoclonality in follicular gastritis: a possible association between follicular gastritis and MALT lymphoma.

Many studies have indicated a close association between gastric mucosa-associated lymphoid tissue (MALT) lymphoma and Helicobacter pylori ( Hp) infection. Follicular gastritis (FG), a rare type of gastritis, is also closely associated with Hp infection and histologically similar to MALT lymphoma. However, there are few studies investigating the relationship between FG and MALT lymphoma. To clarify the issue, we examined the B-cell monoclonality in FG by immunoglobulin heavy chain (IgH) gene rearrangement. Seventy FG patients (all Hp-positive, 23 males and 47 females, median age 33 yr) were investigated; 70 age-and gender-matched non-FG Hp-positive controls and 24 non-FG Hp-negative controls were also examined. Two gastric biopsies, one from the antrum and one from the corpus, were obtained from each patient. DNA was extracted from formalin-fixed, paraffin-embedded biopsy specimens. IgH gene rearrangement was examined by semi-nested polymerase chain reaction (PCR). In the antral mucosa, monoclonal B-cell populations were detected in 19 (32%) of 60 FG, in 6 (10%) of 60 Hp-positive controls, and in none of 20 Hp-negative controls. In the corporal mucosa, monoclonal B-cell populations were detected in 14 (30%) of 47 FG, in 6 (11%) of 54 Hp-positive controls, and in none of 20 Hp-negative controls. The incidence of monoclonal B-cell populations in the FG patients was higher than in both Hp-positive and Hp-negative controls ( P<0.05). The monoclonal B-cell populations disappeared after successful Hp eradication in 8 of 8 FG patients examined. These data suggest that FG may be strongly associated with MALT lymphoma, and that Hp eradication therapy may be indicated in FG.

Adolescent↗

PubMed2002

Is gastroscopy still a valid diagnostic tool in detecting gastric MALT lymphomas? A dilemma beyond the eye. Mucosa-associated lymphoid tissue.

BACKGROUND: Primary gastric lymphomas are distinct entities with an indolent clinical course and biologic behavior. They account for 2-8% of all gastric malignancies. We conducted this study to evaluate the role of gastroscopy as the principal diagnostic method in detecting gastric MALT lymphomas. METHODS: Sixty-three consecutive patients with gastric MALT lymphomas, who were evaluated and treated at our institution between January 1978 and December 1997, are retrospectively reviewed. There were 36 males and 27 females, with a mean age of 53 years (range 20-80 years). All patients underwent the standard diagnostic evaluation, including gastroscopy and biopsy. Patients were staged according to revised Musshof modification of the Ann Arbor classification system, whereas histological evaluation was made according to the Isaacson classification system for gastric MALT lymphomas. RESULTS: According to endoscopic findings, the antrum harbored the neoplasm in 31 patients (49%), the body in 38% (24 patients), and the fundus in 4% (3 patients), whereas in 5 patients (8%) the neoplasm occupied the entire stomach. The macroscopic appearance was not in most cases pathognomonic of the disease. Three macroscopic patterns were recognized at endoscopy: (a) the ulcerative in 51% (32 patients), (b) the polypoid in 33% (21 patients) and (c) the diffuse infiltrative in 16% (10 patients). The neoplasm was characterized as a benign disease in 24 patients (38%), with malignancy being suspected in 62% (39 patients). Endoscopy displayed a sensitivity of 61% in detecting malignancy; however, the sensitivity dropped to 27% when endoscopic diagnosis of non-Hodgkin's lymphoma was hypothesized. CONCLUSIONS: Although the impact of gastroscopy as a diagnostic tool in the patients of our study was of limited value, due to the nonspecific gross pattern of gastric MALT lymphomas, it should be maintained in the diagnostic intervention of the upper GI tract pathologies.

Adult↗

PubMed2000

Gastric MALT lymphomas: the value of an endoscopic follow-up evaluation.

BACKGROUND: Findings have demonstrated the close association between primary gastric B-cell lymphomas originating from mucosa-associated lymphoid tissue (MALT) and Helicobacter pylori (HP) infection, with their regression after an HP eradication therapy in up to 70% of the cases. Endoscopic-biopsy diagnosis and endoscopic ultrasound are of major importance as decisive prognostic factors and therapeutic determinants. OBJECTIVES: We report 3 years of experience and follow-up evaluation in the management of MALT lymphomas. We also describe the guidelines strategy therapy used in our institution. METHODS: Since July 1996, nine patients with a histologic diagnosis of low-grade, HP-positive MALT gastric lymphomas, have been followed up. All patients had stage IE lymphomas (according to Musshoff classification). Eradication of HP was performed with triple therapy amoxycillin, clarithromycin, and omeprazole using over a 14-day period. The patients were seen for endoscopic follow-up assessment after 3, 6, 9, and 15 months, then twice a year. The actual median follow-up time was 30.4 months (range, 16-38 months). RESULTS: All the patients are now free of disease and asymptomatic. We have registered two cases of HP relapse (both after 1-year follow-up evaluation), positively treated with the same triple therapy, and three cases of disease relapse treated with single-dose chemotherapy (plus radiotherapy in one patient). CONCLUSIONS: In our experience the eradication of HP appears to be effective, and we consider it the first therapeutic option in patients with stage IE gastric low-grade MALT lymphoma, although long-term results are still needed. Prolonged follow-up evaluation (particularly by endoscopy) is necessary (and feasible in our experience) to determine whether these remissions are long-lasting. We recommend that HP be eradicated in these lymphomas before referral to other standard treatment.

Aged↗

PubMed2005

Deep infiltrative low-grade MALT (mucosal-associated lymphoid tissue) colonic lymphomas that regressed as a result of antibiotic administration: endoscopic ultrasound evaluation.

Since 1997 we have experienced three cases of low-grade colonic mucosal-associated lymphoid tissue (MALT) lymphomas. The depth of tumor invasion was evaluated by endoscopic ultrasonography (EUS) and the mass lesions were all diagnosed as having extended beyond the deep region of the submucosal layer. Although all of these patients tested negative for gastric Helicobacter pylori, their tumor lesions regressed after antibiotic treatment in accordance with H. pylori eradication therapy. In general, consensus has been reached regarding antibiotic therapy for gastric MALT lymphomas. However, as a prerequisite for antibiotic therapy, the therapy has been deemed effective against these gastric tumors if the extent of infiltration, as evaluated by EUS, is limited to the mucosal layer or the superficial region of the submucosal layer. Based on the therapeutic outcomes seen in the three patients studied here, it is suggested that antibiotic therapy might be useful in treating MALT lymphomas of the colon, even in patients with advanced invasive tumors, in contrast to the extent of the lesions in the stomach suitable for antibiotic treatment. The success of the antibiotic treatment also suggests that MALT lymphomas may be caused by unknown luminal microorganisms, other than H. pylori.

Aged↗

PubMed2006

Successful treatment of Helicobacter pylori-negative gastric MALT lymphoma with rituximab.

Helicobacter pylori infection is strongly associated with low-grade gastric lymphoma, commonly known as mucosa-associated lymphoid tissue (MALT) lymphoma. H. pylori eradication leads to complete remission in 80% of early stage MALT lymphomas. The treatment for early stage H. pylori-negative gastric MALT lymphoma is evolving. Rituximab, a chimeric anti-CD20 antibody, has shown response rates of approximately 50% with minimal toxicity in patients with B-cell non-Hodgkin lymphoma. We describe herein the clinical, endoscopic, and histologic features of a patient with H. pylori-negative gastric MALT lymphoma treated successfully with rituximab.

Aged↗

PubMed2001

Long-term follow-up of gastric MALT lymphoma after H. pylori eradication.

For almost 10 years, we have been familiar with the concept of mucosa-associated lymphoid tissue (MALT)-type lymphoma of the stomach caused by chronic Helicobacter pylori infection. Many epidemiologic, biologic, and molecular genetic studies have implicated H. pylori for its role in lymphoma genesis. Since the first reports on complete remission of gastric MALT lymphomas after cure of bacterial infection, many clinical studies have investigated the effect of eradicating H. pylori on the course of MALT lymphoma, and indeed were able to confirm remission of the lymphoma. To date, more than 650 patients worldwide have been treated for gastric MALT lymphoma with antibiotics, and we have gained many new insights concerning the biologic behavior of this disease, especially from the deepened knowledge of cytogenetics. Furthermore, factors relevant for the prediction of treatment outcome have been identified, which has helped to stratify patients into risk groups.

Follow-Up Studies↗

PubMed2006

Lacrimal gland extranodal marginal zone B-cell lymphoma of MALT-type.

PURPOSE: To evaluate the clinical features and outcome of extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue type (MALT lymphoma) in the lacrimal gland. DESIGN: Retrospective, noncomparative, observational case series in an academic referral setting. METHODS: A consecutive series of 13 histologically verified MALT lymphoma in the lacrimal gland at presentation was studied. Clinical characteristics, treatment, and prognosis were analyzed. RESULTS: Eight males and five females with a median age of 64 years and a median follow-up time of 48 months were included. All patients had no prior lymphoma and initially presented as MALT lymphoma in the lacrimal gland. Extraorbital involvement at diagnosis was noted in six patients (46.2%). Two patients had autoimmune disease, and both had Stage IV disease at presentation. Treatment consisted of surgical resection in one patient, radiotherapy in four, chemotherapy in four, and combined radiotherapy and chemotherapy in four. Complete remissions were obtained in eight patients (61.5%). Patients with bilateral disease (61.5%) had a higher rate of advanced-stage disease and a poor outcome. Recurrence was noted in two patients. At the last follow-up, eight patients were free of disease, three were alive with disease, one died of sepsis as a complication of chemotherapy, and one died of lymphoma. CONCLUSIONS: MALT lymphoma in the lacrimal gland has a high rate of extraorbital involvement and synchronous bilateral lacrimal gland involvement at presentation. The prognosis is relatively poor, especially in patients with advanced disease and bilateral involvement. Extensive staging and long-term follow-up are warranted for these patients.

Adult↗

PubMed2006

Frequency of chromosomal aneuploidies and deletions of the RB and TP53 genes in MALT lymphomas harboring the t(14;18)(q32;q21).

The t(14;18)(q32;q21) involving the MALT1/MLT and IGH genes has been identified recently as a recurrent abnormality in mucosa-associated lymphoid tissue (MALT) lymphomas. The frequency of secondary chromosomal aberrations in MALT lymphomas harboring the t(14;18) is largely unknown. We therefore analyzed six t(14;18)-positive MALT lymphomas (five parotid, one conjunctiva) by interphase fluorescence in situ hybridization for aneuploidies of chromosomes 3, 7, 12, 18, and X, gains or disruption of the CMYC/8q24 and BCL6/3q27 genes, as well as deletions of the retinoblastoma and TP53 tumor suppressor genes. Except for one MALT lymphoma of the parotid with trisomy 3, neither aneuploidies nor deletions were detected in any of our cases.

Aneuploidy↗