Systemic humoral anti-Helicobacter pylori immune response in patients with gastric malignancies and benign gastroduodenal disease

BACKGROUND/AIMS

Helicobacter pylori elicits a strong local and systemic humoral immune response, but it is not able to eliminate bacteria. Immune response may be important for the course of infection that may lead to different gastroduodenal disease. In order to investigate differences in systemic humoral immune response between patients with different gastroduodenal diseases, we conducted clinical and serological studies.

METHODOLOGY

From 1999 to 2001 we enrolled 80 patients with dyspeptic symptoms: 26 with gastritis, 12 with duodenal ulcer, 29 with gastric cancer and 13 with gastric lymphoma. In all patients during diagnostic work-up we performed ELISA test with Helicobacter pylori-specific IgG and IgA. We investigated difference in stimulation of different immunoglobulin classes in patients with different gastroduodenal diseases, particularly benign and malignant. We estimated significance of differences with Mann-Whitney and Fisher exact probability test.

RESULTS

All patients enrolled in the study were seropositive. Patients with gastritis had statistically significant higher level of IgG than patients with gastric cancer (p=0.0001), and gastric lymphoma (p=0.006). Patients with duodenal ulcer had statistically significant higher level of IgG than patients with gastric cancer (p=0.02), and gastric lymphoma (p=0.046). IgA level was significantly higher in patients with gastritis than in patients with gastric cancer (p=0.03). IgA>IgG ratio was significantly more frequent in patients with gastric cancer and gastric lymphoma than in patients with gastritis and duodenal ulcer (p=0.0002).

CONCLUSIONS

Result of our study suggested that Helicobacter pylori elicits different systemic humoral immune response in patients with gastritis and duodenal ulcer than in patients with gastric cancer and gastric lymphoma at least in intensity of stimulation of different immunoglobulin classes.

Helicobacter pylori infection in Finland

Helicobacter pylori causes chronic gastritis worldwide and it is the most important single factor in peptic ulcer disease. Up to half of H. pylori infected individuals develop atrophic gastritis over years and decades. H. pylori infection has also been classified as a class I carcinogen in human gastric cancer. Most infections are obtained in childhood, in Finland mainly before the age of 7 years but the exact transmission routes are not known. The infection shows an age-dependent pattern, the infection being rare among children but gradually becoming more prevalent among older age groups. As new infections are few in adults and the infection only rarely disappears without effective anti-microbial therapy, the occurrence of the infection in the old actually reflects the prevalence of the infection in their childhood. In developed countries, such as Finland, a rapid decline of H. pylori prevalence rate has been demonstrated. In order to speed up this natural decline of the infection, a unique population based 'screen and treat' project was started in Vammala, a semiurban south-western community in Finland. In this survey, young inhabitants were offered diagnosis and treatment for H. pylori.

Fusobacterium nucleatum: a rare cause of bacteremia in neutropenic patients with leukemia and lymphoma

Although anaerobic bacteremias are uncommon in oncohematologic patients, nevertheless they have been considered an emergent problem in the last few years. Fusobacterium nucleatum is an anaerobic Gram-negative bacillus commonly present in the oral cavity and in the respiratory and genito-urinary tracts. Over a 10-year period 18 episodes of F. nucleatum bacteremia in patients with hematological malignances (15 leukemias and 3 lymphomas) have been observed in our Department of Hematology. Predisposing factors included oropharyngeal mucositis and severe neutropenia owing to intensive chemotherapy. In our experience no septic shock occurred and the outcome of bacteremias caused by F. nucleatum was favorable.

[Identification of Helicobacter pylori and associated gastric lesions]

In this study is presented a silver stain technique for Helicobacter pylori with ammoniacal silver carbonato of Del Río Hortega, in biopsies and surgical specimens embebbed in paraffine. This study was performed between 1999 to 2001, and 717 gastroscopics biopsies were observed, that included: 705 chronic gastritis (98.32%), 11 gastric carcinomas (1.53%), and 1 low-grade lymphoma (0.13%). It is important to note the low incidence of adenocarcinomas and lymphomas from 717 gastroscopic biopsies during the period of 1999-2001, only 11 carcinomas and 1 lymphoma. We added 28 retrospective studies of biopsies and surgical specimens. These latter group included 21 adenocarcinomas and 7 low-grade lymphomas. Hence, there were a total of 745 cases with: 705 chronic gastritis, 32 adenocarcinomas, and 8 low-grade lymphomas. In 705 chronic gastritis, 325 (46.10%) were associated with H pylori, and they were Chronic Superficial Gastritis of Mild (8.62%), Moderate (61.23%), and Severe (12.92%) intensity; and Follicular Gastritis in 17.23%. In a serie of 82 total Follicular Gastritis (82/705), H pylori was founded in 68.29% (56/82). This relative frequency of association between H pylori with Chronic Gastritis in general (46.10%), and with Follicular Gastritis in particular (68.29%), could be explain because: a--many gastroscopic biopsies did not became from antrum, site of H pylori growing. Or b--there was another etiologic factor without morphologic value. There is a clear evidence that H pylori is an important factor in the pathogenesis of these chronic gastritis, from primary Acute Gastritis occurred in children and young patients, to Chronic Superficial Gastritis, Follicular Gastritis, Atrophic Gastritis, intestinal metaplasia, and Peptic Ulcer present in adult patients. Adenocarcinomas were associated with moderate and severe Chronic Superficial Gastritis, Atrophic Gastritis, intestinal metaplasia, and moderate and severe dysplasias of glandular epithelium. H pylori was founded in only 35% of adenocarcinomas, probably related to the presence of atrophic gastritis associated with metaplastic/dysplastic changes, or necrotic tissues, which would possibly explain the absent of H pylori growing under these circumstances. Low-grade lymphomas (MALT-type), arise from lymphatic tissue of the mucosa, and were associated with chronic gastritis, atrophy, and intestinal metaplasia. H pylori was founded in 75% of all lymphomas. Also in this case, there is a clear pathogenic evidence between H pylori infection and the development of low-grade lymphoma, specially in early stages, since it is possible the complete resolution after antibiotic therapy or partial gastrectomy.

Two-year follow-up of Helicobacter pylori infection in C57BL/6 and Balb/cA mice

Helicobacter pylori infection is associated with chronic gastritis, peptic ulcer disease, gastric adenocarcinoma and MALT lymphoma. We previously found high-grade lymphoma after 13 months' H. pylori infection in C57BL/6 mice. In this study we followed H. pylori infection by three different isolates in C57BL/6 and Balb/cA mice for 23 months. Six-week-old C57BL/6 and Balb/cA mice were infected with H. pylori strains 119p (CagA+, VacA+), SS1 (CagA+, VacA+) and G50 (CagA-, VacA-). Mice were followed at 2 weeks, 10 weeks and 23 months post-inoculation (p.i.) by culture, histopathology and serology. Strain G50 was only reisolated from mice 2 weeks p.i. There was no difference in colonization between strain 119p and SS1 at 10 weeks p.i., whereas SS1 gave 100% colonization versus 119p gave 50% 23 months p.i. Interestingly, the inflammation score was higher in mice infected with strain 119p than with SS1 10-week p.i., and there were lymphoepithelial lesions in mice infected with strain 119p and G50 but not with SS1 at 23 months post-infection. Eight mice infected with strains 119p and G50 developed gastric lymphoma (grade 5 and 4). One C57BL/6 mouse infected with strain 119p developed hepatocellular carcinoma after 23 months. Immunoblot showed specific bands of 26-33 kDa against H. pylori in infected mice, and two mice infected with strain SSI reacted with antibodies to the 120 kDa CagA toxin.

CONCLUSION

A reproducible animal model for H. pylori-induced lymphoma and possibly hepatocellular carcinoma is described. Strain diversity may lead to different outcomes of H. pylori infection.

Distinct gene expression profiles characterize the histopathological stages of disease in Helicobacter-induced mucosa-associated lymphoid tissue lymphoma

Long-term colonization of humans with Helicobacter pylori can cause the development of gastric B cell mucosa-associated lymphoid tissue lymphoma, yet little is known about the sequence of molecular steps that accompany disease progression. We used microarray analysis and laser microdissection to identify gene expression profiles characteristic and predictive of the various histopathological stages in a mouse model of the disease. The initial step in lymphoma development is marked by infiltration of reactive lymphocytes into the stomach and the launching of a mucosal immune response. Our analysis uncovered molecular markers of both of these processes, including genes coding for the immunoglobulins and the small proline-rich protein Sprr 2A. The subsequent step is characterized histologically by the antigen-driven proliferation and aggregation of B cells and the gradual appearance of lymphoepithelial lesions. In tissues of this stage, we observed increased expression of genes previously associated with malignancy, including the laminin receptor-1 and the multidrug-resistance channel MDR-1. Finally, we found that the transition to destructive lymphoepithelial lesions and malignant lymphoma is marked by an increase in transcription of a single gene encoding calgranulin AMrp-8.

[Incidence of bacteremia among histologic groups of hematologic malignancies]

INTRODUCTION

Subgroups having dissimilar prognoses are being identified among cancer patients with infection. Previous studies have suggested that these differences may be related to the histologic diagnosis, but this issue has not as yet been demonstrated.

METHODS

We reviewed the medical records of all patients admitted with acute leukemia (AL) or lymphoma (ML) from 1988 to 1998. Incidence of bacteremia was calculated for the following subgroups: acute lymphocytic leukemia (ALL), acute myelocytic leukemia (AML), AML following refractory anaemia with excess blasts (AML-RAEB), high-grade ML (HGML), intermediate-grade ML (IGML), low-grade ML (LGML) and indeterminate ML (IML). Kaplan-Meier curves of time to the first positive blood culture were constructed and compared by means of log-rank test.

RESULTS

In the period covered there were 244 new diagnoses of AL or ML: 62 AML, 32 ALL, 20 AML-RAEB, 78 HGML, 7 IGML, 37 LGML and 6 IML. At the end of the study period, 44 patients were alive, 147 were known to have died at a certain date and 53 had been formally lost to follow-up (most of them, transferred for hospice care). Among 684 blood cultures, there were 51 contaminations and 155 significant isolates. Among the latter, gram-positive bacteria were isolated in 74 and gram-negative bacteria in 47; in 27 cases more than 1 bacterial species were recovered. Fungi were isolated in 7 cases. The incidence of bacteremia expressed as cases per 1000 patient-days was 5.80 for AML, 5.03 for AML-RAEB, 1.56 for ALL, 0.21 for HGML and 0.40 for the remaining ML. Time to the first positive blood culture was significantly shorter for AML than for any other group, and was shorted for ALL and AML-RAEB than for ML.

CONCLUSION

Differences in the incidence of bacteremia were observed among histologically-defined groups of unselected patients with hematologic malignancies.

[Primary gastric lymphoma: a case report]

In this case report the Authors describe a case of primary gastric lymphoma in a 62 years old patient who presented with dyspepsia and weigh loss. Primary gastric lymphoma is a rare neoplasm which of 1-10% of the malignant gastric neoplasms in the gastroenteric tract. The clinic presentation is usually aspecific. The infection by H. pylori is a factor of predisposition for this kind of disease. The diagnostic pathway consists in x-ray examination of the gastrointestinal tract, the endoscopy with biopsies, the computerized tomography and the echo-endoscopy. However obtaining a preoperative diagnosis is often difficult because of the submucosal localization of the lymphoma. There is not a common strategy among the Authors for the treatment of the disease, which can be surgical, radiotherapic or chemotherapic.

Clinical evaluation of a polymerase chain reaction assay to detect Aspergillus species in bronchoalveolar lavage samples of neutropenic patients

The increasing incidence of invasive aspergillosis, a life-threatening infection in immunocompromised patients, emphasizes the need to improve the currently limited diagnostic tools. Using a recently developed two-step polymerase chain reaction (PCR) assay to detect 10 fg of Aspergillus DNA, corresponding to 1-5 colony-forming units (CFU)/ml of spiked samples in vitro, we prospectively examined 197 bronchoalveolar lavage (BAL) samples from 176 subjects, including 141 neutropenic, febrile patients with lung infiltrates, at risk for invasive fungal disease. Underlying diseases of these patients were haematological malignancies; 93 patients suffered from acute leukaemias. Thirty-one of these immunocompromised patients (17.6%) were PCR positive, correlating with positive BAL culture, positive histology from lung surgery or from autopsy, positive computerized tomography scans or positive galactomannan enzyme-linked immunosorbent assay. Six patients (4.3%) of this group had positive PCR results without any correlation to clinical or other diagnostic data, probably owing to contamination of the samples by ubiquitous Aspergillus spores. The samples of two patients (1.4%) with a subsequent histologically proven mould infection were PCR negative. All 102 immunocompromised patients (72.3%) with a negative PCR showed no evidence of invasive fungal disease. From 35 patients without immunodeficiency, four (11.4%) showed positive results, without evidence of invasive or non-invasive pulmonary aspergillosis. In this haematological population, the sensitivity and specificity values of the test reached 93.9% and 94.4%, the positive predictive value 83.8%, the negative predictive value 98.1%. Our data support the considerable clinical value of this PCR assay for confirming and improving diagnosis of pulmonary aspergillosis in high-risk patients.

Invasive fungal infections after allogeneic peripheral blood stem cell transplantation: incidence and risk factors in 395 patients

We have analysed the incidence and risk factors for the occurrence of invasive fungal infections (IFI) among 395 recipients of an allogeneic peripheral blood stem cell transplantation (PBSCT) from a human leucocyte antigen (HLA)-identical sibling. IFI (n = 50) occurred in 46 patients, giving an overall probability of 14%. There were 12 cases of invasive candidiasis (3%), with only one death. Non-Candida IFI occurred in 37 patients (12% probability), mostly invasive aspergillosis (n = 32). In multivariate analysis the only two significant variables associated with a higher risk of developing a non-Candida IFI were the development of moderate-to-severe graft-versus-host disease (GvHD, P < 0.0001; OR 4.6) and having received steroid prophylaxis for GvHD (P = 0.04; OR 2.1). In multivariate analysis the variables associated with a lower overall survival after PBSCT were development of a non-Candida IFI (P < 0.0001; OR 5.6), non-early disease phase (P = 0.0001; OR 1.9), steroid prophylaxis (P = 0.02; OR 1.4), moderate-to-severe GvHD (P = 0.01; OR 1.6) and cytomegalovirus infection post transplant (P = 0.001; OR 1.8). Our results show that non-Candida IFI (in particular aspergillosis) was an important cause of infectious morbidity and mortality after an HLA-identical sibling PBSCT, while invasive candidiasis was rare. Use of steroid prophylaxis and, in particular, the development of moderate-to-severe GvHD post transplant were risk factors for non-Candida IFI. Prophylactic strategies for these infections should thus take into account these risk factors.

Prevention of mycoplasma contamination in leukemia-lymphoma cell lines

The contamination of cell lines with mycoplasmas is certainly one of the major problems occurring in cultured cells. Analyzing more than 460 human leukemia-lymphoma (LL) cell lines, we found that 28% of the cultures were mycoplasma-positive. Mycoplasmas can produce extensive changes, growth arrest and cell death in the infected cultures. While mycoplasma-infected cell lines can be truly cleansed from the contaminants, all the efforts would be in vain when the cells return to a mycoplasma-infested environment or are handled with unsuitable culture practices. Hence, the main focus of mycoplasma control should be on preventing cell culture contamination. Mycoplasmas can be introduced through several routes including culture reagents and laboratory personnel. Cross-contamination from infected cell cultures within one laboratory continues to be the major source for the spread of mycoplasma. Specific technical protocols and cell culturing guidelines may be followed in order to minimize the risk of mycoplasma contamination of cell lines. This "good culture practice" is of utmost importance as faulty cell culture techniques appear to be also the main reason for the high incidence of cross-contaminated LL cell lines which according to our experience using DNA fingerprinting of some 500 LL cell lines is about 15%.

Pathological disorders of the gastric mucosa surrounding carcinomas and primary lymphomas

OBJECTIVE

Gastritis, intestinal metaplasia, atrophy, and dysplasia are disorders that frequently precede the full development of gastric adenocarcinoma. On the other hand, primary gastric lymphomas seem to arise from mucosa-associated lymphoid tissue. It is well accepted that these histological changes are caused by Helicobacter pylori infection. The objective of this study is to determine the frequency and characteristics of epithelial and lymphoid tissue disorders of the gastric mucosa surrounding primary carcinomas and lymphomas.

METHODS

We studied 111 gastrectomies from patients harboring primary adenocarcinomas (30 intestinal and 30 diffuse type) and 51 gastric lymphomas. For comparative purposes, we analized 86 stomachs from patients who died of diseases other than gastric malignancies. Histopathological disorders of the gastric mucosa adjacent to primary neoplasms such as atrophy, intestinal metaplasia, and dysplasia were recorded. Lymphoid follicles were classified in two groups, with or without expansion. Expansion was characterized by increased size, irregular borders, enlarged marginal zone, and expanded germinal centers. Differences were statistically evaluated with chi2 and Fisher exact tests, odds ratio, and relative risk, with 95% CI. p values <0.05 were considered statistically significant.

RESULTS

Most intestinal-type adenocarcinomas showed atrophy (76.6%) and intestinal metaplasia (86.6%) and less frequently, dysplasia (23.3%), in the surrounding gastric mucosa. Expansive lymphoid follicles were more frequent among lymphomas than in adenocarcinomas (56.8% vs 25%); however, a high percentage of lymphomas were also associated with atrophy (50.9%), intestinal metaplasia (62.7%), and rarely dysplasia (11.8%). On the contrary, diffuse-type adenocarcinoma displayed less frequently atrophy (33%), intestinal metaplasia (50%), and dysplasia (3%). Gastric mucosa from patients without any gastric neoplasia was almost normal (84%), whereas the remaining 16% showed, both or alone, atrophy and intestinal metaplasia.

CONCLUSION

Histopathological disorders of the gastric mucosa are not specific for any neoplasm, but intestinal-type adenocarcinomas frequently showed atrophy, intestinal metaplasia, and not uncommonly, dysplasia of the surrounding non-neoplastic gastric mucosa. Diffuse-type adenocarcinomas did not frequently show such lesions. Primary lymphomas displayed expansive lymphoid follicles and also a high percentage of atrophy and intestinal metaplasia of the surrounding gastric mucosa. The presence of intestinal metaplasia, atrophy, and lymphoid follicles with expansion in endoscopic biopsies could suggest a higher suceptibility for the development of gastric intestinal-type adenocarcinoma or gastric lymphoma. Patients harboring such histopathological changes must receive eradication therapy against H. pylori and probably closer follow-up.

Seroprevalence of Helicobacter pylori infection in patients with lymphoma

To determine the Helicobacter pylori (HP) seroprevalence in patients with non-Hodgkin's lymphoma (NHL) and other hematological conditions. Sera were collected from 444 patients with NHL, Hodgkin's disease (HD), lymphoproliferative disorders (LPD), myeloproliferative disorders (MPD), and other hematological conditions. HP seropositivity was determined by ELISA and the results were compared among diagnostic groups HP seropositivity was observed in 168/444 (38%) of the total population. Higher seropositivity rates were associated with increasing age (p=0.001), and country of birth outside the USA and Canada (p=0.0001). Among the diagnostic groups, patients with NHL demonstrated the highest frequency (43%) and those with HD, the lowest frequency (20%; p=.026) of HP seropositivity. The differences among diagnostic groups remained statistically significant after controlling for country of birth (p<0.05), but not after controlling for patient age at diagnosis. The HP seroprevalence of G1 NHL was 55% compared to 40% for non-G1 NHL (p=NS). The highest rate of HP seropositivity (67%) occurred in gastric MALT lymphoma patients, although this did not reach statistical significance compared to the non MALT group (50%) due to small sample size. In conclusion, the rate of HP seropositivity in patients with MALT lymphoma in the USA appears to be lower than in Europe. Helicobacter pylori does not appear to be an important factor in other types of NHL of the G1 tract or elsewhere. Studies of HP prevalence should be controlled for country of birth as well as for age.

Actinomyces and actinobacillus actinomycetemcomitans-Actinomyces-associated lymphadenopathy mimicking lymphoma

We present 2 unusual cases of long-standing, extensive reactive lymphadenopathy secondary to Actinomyces infection, 1 of which was also accompanied by Actinobacillus actinomycetemcomitans-Actinomyces complex infection. To our knowledge, histologic features of lymph node involvement by these organisms have not been previously reported in the literature. One patient had extensive cervical, posterior mediastinal, and abdominal lymphadenopathy. The second patient presented with a submandibular mass and cervical lymphadenopathy. Clinical features strongly suggested lymphoma. The histologic examination of the lymph nodes from both patients revealed reactive follicular hyperplasia, marked interfollicular and capsular fibrosis, and multiple interfollicular microabscesses. Characteristic Actinomyces colonies were identified at the center of the microabscesses in deep sections. Cultures were obtained from the lymph nodes of 1 patient, and were positive for A actinomycetemcomitans. Both patients had poor dental hygiene. Lymphadenopathy subsided with antibiotic therapy and appropriate dental care.

[Helicobacter pylori and gastric neoplasms: adenocarcinoma and lymphoma]

Helicobacter pylori is a risk factor for gastric carcinoma and an established carcinogenic bacterium. The relative risk to induce a gastric cancer is estimated to be 3 to 6 compared to that of individuals without H. pylori. Gastric atrophy and intestinal metaplasia in gastric mucosa are 2 well recognized precancerous lesions. Their occurrence and evolution are multifactorial depending on age at first infection, duration of infection and host's genetic characteristics. Prevention using H. pylori eradication is recommended only in individuals with high risk of cancer. Gastric lymphoma, although less frequent, may be due to H. pylori infection. Only in low grade lymphoma H. pylori eradication and periodic surveillance are recommended.

Gastrointestinal lymphomas: the Würzburg study experience

Appropriate management of primary gastric lymphomas is still controversial. We, therefore, conducted a prospective multicenter study to identify its clinical features, evaluate the accuracy of diagnostic and staging procedures, and assess a treatment strategy based on tumor stage and malignancy. Of 266 patients recruited within three years, 107 had low-grade (40%) and 159 high-grade (60%) lymphoma. A total of 237 patients (89%) presented with localized disease (stages EI/II). Based on the rapid urease test and/or histology the overall Helicobacter pylori positivity was 59% (76%, 51%, 38% in low-grade, high-grade, and secondary high-grade lymphoma, respectively). In 27% of the cases, patients could not be precisely classified and graded on the basis of endoscopic biopsies. In 78 patients, pre-operative endoscopic ultrasound correctly predicted the depth of tumor infiltration in 78% and lymph-node involvement in 75%. Treatment was stratified according to the grade of malignancy and stage: H. pylori eradication in low-grade lymphoma of stage EI, surgical resection in stages EI/II of low- and high-grade lymphoma and, depending on the pathohistological stage and post-operative residual tumor mass radiation and chemotherapy/combined radiochemotherapy in low-grade and high-grade lymphoma, respectively.

Helicobacter pylori. One bacterium and a broad spectrum of human disease! An overview

Since the historical rediscovery of gastric spiral Helicobacter pylori in the gastric mucosa of patients with chronic gastritis by Warren and Marshall in 1983, peptic ulcer disease has been largely viewed as being of infectious aetiology. Indeed, there is a strong association between the presence of H. pylori and chronic active gastritis in histology. The bacterium can be isolated in not less than 70% of gastric and in over 90% of duodenal ulcer patients. Eradication of the organism has been associated with histologic improvement of gastritis, lower relapse rate and less risk of bleeding from duodenal ulcer. The bacterium possesses several virulence factors enabling it to survive the strong acid milieu inside the stomach and possibly damaging host tissues. The sequence of events by which the bacterium might cause gastric or duodenal ulcer is still not fully elucidated and Koch's postulates have never been fulfilled. In the majority of individuals, H. pylori infection is largely or entirely asymptomatic and there is no convincing data to suggest an increase in the prevalence of peptic ulcer disease among these subjects. An increasingly growing body of literature suggests an association between colonization by H. pylori in the stomach and a risk for developing gastric mucosa-associated lymphoid tissue (MALT), MALT lymphoma, gastric adenocarcinoma and even pancreatic adenocarcinoma. The bacterium has been implicated also in a number of extra-gastrointestinal disorders such as ischaemic heart disease, ischaemic cerebrovascular disease, atherosclerosis, and skin diseases such as rosacea, but a causal role for the bacterium is missing. Eradication of H. pylori thus seems to be a beneficial impact on human health. Various drug regimens are in use to eradicate H. pylori involving the administration of three or four drugs including bismuth compounds, metronidazole, clarithromycin, tetracyclines, amoxycillin, ranitidine, omeprazole for 1-2 weeks. The financial burden, side effects and emergence of drug resistant strains due to an increase in the use in antibiotics for H. pylori eradication therapy need further reconsideration.

Kaposi's sarcoma-associated herpesvirus: from cell biology to pathogenesis

Kaposi's sarcoma-associated herpesvirus (KSHV or HHV-8) is linked to the etiopathogenesis of Kaposi's sarcoma, a plasma-blastic variant of Castleman's disease and primary effusion lymphoma. KSHV is related to a number of non-human primate viruses. Only a limited number of KSHV proteins are expressed in tumor cells. Here we discuss the putative role of these proteins in KSHV pathogenesis.

Splenic rupture in children with hematologic malignancies

BACKGROUND

Splenic rupture is an uncommon but life-threatening complication of leukemias and lymphomas, and is reported mostly in adults. The authors investigated the frequency with which splenic rupture is diagnosed in pediatric patients with hematologic malignancies and reviewed its clinical profile and outcome.

METHODS

The data base of St. Jude Children's Research Hospital was searched for cases coded as splenic laceration or rupture, splenic infarction, or splenectomy in patients diagnosed with lymphoma or leukemia between January 1962 and December 1997. The medical records of patients with histopathologic or radiologic evidence of splenic rupture were reviewed. The time spanned by the study was divided into early (1962-1990) and recent (1991-1997) eras to reflect the availability of modern diagnostic imaging techniques.

RESULTS

Seven children experienced splenic rupture. They were between ages 5-17 years. There were four males and three females. Primary diagnoses included acute myeloid leukemia (four patients), acute lymphoblastic leukemia (two patients), and Hodgkin lymphoma (one patient). Five patients were diagnosed in the recent era and two in the early era. Four patients had radiologic or bacteriologic evidence of fungal infection concomitant with the splenic event. Of five deaths, only two were related causally to splenic rupture; these occurred in the early era. All seven acute episodes of splenic rupture were managed conservatively without surgery.

CONCLUSIONS

The overall frequency with which splenic rupture was detected in children with hematologic malignancy at the study institution was 0.18%. In the recent era, the frequency of detection was 9-fold higher (0.55%) than that of the early era (0.06%). Improved imaging techniques and increased utilization of imaging studies may account for the increased incidental detection of "preclinical" splenic rupture. Adolescent age group, acute myeloid leukemia (especially acute promyelocytic leukemia), a high leukocyte count, thrombocytopenia, and coagulopathy may predispose children with leukemia to pathologic splenic rupture. Fungal infection frequently was associated with splenic rupture and may play a role in its pathogenesis.

Lymphoid proliferations and lymphomas associated with gastric metaplasia, dysplasia, and carcinoma

Gastric carcinomas are invariably accompanied by lymphoid proliferations. We studied their features in 22 resected gastric carcinomas in which the lymphoid proliferations ranged from reactive lymphoid follicles to mucosa-associated lymphoid tissue (MALT) lymphomas. In most cases, the collections of lymphocytes were abundant, which is remarkable considering the lack of lymphoid tissue in the normal stomach. They were not haphazardly located but in direct contact with the metaplastic, dysplastic, and neoplastic epithelial cells, in positions suggestive of defense barriers. They consisted of newly formed lymphoid follicles with reactive germinal centers sometimes high up in the superficial mucosa, collections of plasma cells beneath the surface epithelium, and large aggregates of B cells above and below the muscularis mucosae as well as abundant T cells. The latter, both CD4+ and CD8+, were seen within metaplastic epithelial cells as well as within carcinomatous glands that were partially destroyed, resembling apparent neoplastic lympho-epithelial lesions (LEL). In three cases, the B cells infiltrating the gastric muscular layers represented MALT-lymphomas adjacent to gastric carcinomas, as confirmed by polymerase chain reaction (PCR) analysis in two cases. In a case of lymphoepithelioma-like carcinoma, the excessive lymphoid cells were predominantly of T-CD8+ type. In this case, EBV identified by EBV-encoded RNA and latent membrane protein was present in large amounts. Helicobacter pylori was seen in only six cases in areas of chronic gastritis that were distant from carcinoma. H. pylori was not present in the areas of metaplasia, dysplasia, or carcinoma. It appears that the lymphoid proliferations accompanying these gastric changes do not arise in response to the pathogenic agent H. pylori, which caused the persistent infection leading to them yet is no longer present, but rather in response to the existence of the abnormal epithelial cells. Thus the lymphoid proliferations consistently associated with gastric metaplasia, dysplasia, and neoplasia may be regarded as immune reactions to the long-term cellular changes triggered by the initial chronic gastritis. On rare occasions, the exaggerated lymphoid proliferations may reach the end of the spectrum, resulting in MALT lymphomas coexistent with gastric carcinomas.

Different gastritis features are linked to different gastric neoplasms

OBJECTIVES

Helicobacter pylori infection induces gastritis, which may evolve to carcinoma or lymphoma. Whether duration of infection and inflammation pattern determine the outcome of the neoplastic process is not known. The aim of this study was to investigate the features of the gastritis associated with neoplasia.

METHODS

Gastritis found in association with carcinoma (100 cases) and lymphoma (45 cases) were graded using the Sydney system.

RESULTS

In particular in the antrum, gastric carcinomas, in particular of the intestinal type, were associated with a chronic (94%, n = 34/36) atrophic (92%, n = 33/36) gastritis and intestinal metaplasia (81%, n = 29/36). In diffuse type carcinomas inflammation was either absent or mild. An active (64%, n = 16/25), chronic gastritis (100%, n = 25/25) with lymphoid hyperplasia (72%, n = 18/25) was found in marginal zone cell lymphoma.

CONCLUSIONS

Our study shows that the (pre)atrophic phases of inflammation are associated with gastric carcinomas. In contrast the active phase of inflammation, characterized by severe activity as well as severe chronicity, is found next to marginal zone cell lymphoma.

Primary central nervous system lymphomas in 72 immunocompetent patients: pathologic findings and clinical correlations. Groupe Ouest Est d'étude des Leucénies et Autres Maladies du Sang (GOELAMS)

We reviewed 72 primary central nervous system lymphomas occurring in immunocompetent patients. The cases were reviewed for clinical data, histology, immunophenotype, bcl-2 and p53 expression, and Epstein-Barr virus association. Follow-up was available for 40 patients included in the Groupe Ouest Est d'étude des Leucénies et Autres Maladies du Sang (GOELAMS) lymphomes cérébraux primitifs (LCP 88) trial. Each diagnosis, requiring a consensus among at least 3 pathologists, was performed according to the recent Revised European-American Lymphoma classification and equivalents in the updated Kiel classification. Tumors were predominantly classified as diffuse large B-cell lymphomas. There were 3 T-cell lymphomas and 1 Hodgkin lymphoma. The proteins bcl-2 and p53 were expressed in 35% and 16% of the tested cases, respectively. Epstein-Barr virus was not found by in situ hybridization except in the case classfied as a cerebral localization of Hodgkin disease. No significant association was found between subtypes, bcl-2 or p53 expression, and patient survival. From the standpoint of their biologic characteristics, primary central nervous system lymphomas are very similar to systemic diffuse large B-cell lymphomas. In contrast to AIDS-related primary central nervous system lymphomas, primary central nervous system lymphomas are rarely associated with Epstein-Barr virus and in immunocompetent patients they express bcl-2 at a relatively low rate.

[A clinical study of six cases of Pneumocystis carinii pneumonia]

OBJECTIVE

To heighten the awareness of pneumocystis carinii pneumonia.

METHOD

Six cases of pneumocystis carinii pneumonia were retrospectively analyzed.

RESULT

The underlying diseases were leukemia, lymphoma, renal transplantation and autoimmune hemolytic anemia. The clinical features were dyspnea, cough and fever. X rays typically showed a bilateral diffuse or patchy interstitial infiltrate. Three cases complicated with acute respiratory failure showed hypoxemia, intrapulmonary shunt and reduced compliance resembling ARDS. CPAP/PEEP was required. High-level PEEP (> 1.47 kPa) can be applied to the refractory hypoxemia. SMZco and dapsone were the initial choice of treatment.

CONCLUSION

The prognosis of pneumocystis carinii pneumonia with acute respiratory failure was poor. Aggressive early diagnosis and treatment were critical to improve survival.

Adhesion inhibition of Mycoplasma iowae to chicken lymphoma DT40 cells by monoclonal antibodies reacting with a 65-kD polypeptide

Tissue- and cell-specific attachment of mycoplasmas is a key aspect of the host-parasite relationship. In this study, monoclonal antibodies (MAbs) recognizing surface membrane polypeptides with molecular masses of 46 kD (p46) and 65 kD (p65), respectively, were examined in a microtiter cell attachment (agglutination) inhibition assay. MAbs MI3, MI6, and MI12 reacting with p65 polypeptide of Mycoplasma iowae inhibited attachment of the organisms to chicken lymphoma (DT 40) cells. One MAb (MI2) that reacted with p65 in immunoblots did not inhibit cell attachment, possibly because of the intrinsic native conformation of the epitope(s) in intact mycoplasmas as opposed to the linear state (sodium dodecyl sulfate denatured) in immunoblots. More pronounced M. iowae adherence inhibition was demonstrated by polyclonal turkey and mouse anti-M. iowae antisera compared with MAbs. Immunogold labelling followed by electron microscopy allowed us to localize the MAb-recognized epitopes on the membrane surface of M. iowae. On the basis of the cell attachment inhibition of M. iowae by specific MAbs (MI3, MI6, and MI12), we propose that the p65 polypeptide plays a role in cytadherence. The ability of polyclonal antisera to inhibit attachment of M. iowae more efficiently than the MAbs suggests that additional epitopes within p65 and/or other proteins are involved in cell attachment.

[Bacteremic episodes in pediatric oncologic patients, especially caused by the Streptococcus viridans group]

BACKGROUND

The management of infectious complications plays a major role in the care for pediatric cancer patients. The majority of infections in the neutropenic patient present as fever of unknown origin without recovering a pathogen from the blood stream. The careful evaluation of bacteremic episodes is essential, since knowledge of the bacterial spectrum expected is crucial for the successful anti-infective treatment.

PATIENTS AND METHODS

From 1985 to 1995 all bacteremic episodes in pediatric oncology patients at the University Children's Hospital Freiburg were retrospectively analyzed with respect to the pathogens encountered, the antibiotic susceptibility profile and the underlying conditions.

RESULTS

Overall, 113 bacteremic episodes were encountered in pediatric oncology patients, 68 of them in patients with hematological malignancies, and 45 in patients with solid tumors. In both patient groups, gram-positive bacteria were predominant with 72% and 58%, respectively. In patients with hematological malignancies, viridans streptococci were the most frequently isolated pathogens (35%) with a relevant morbidity (29% of patients developed a severe sepsis syndrome and/or ARDS), but were found only in 9% of patients with solid tumors. In 28% of patients with leukemia or lymphoma, gram-negative rods were cultured, in 6% Pseudomonas spec., in 4% Acinetobacter spec., and in 18% enterobacteria. In patients with solid tumors, in 38% gram-negative rods were isolated, 7% Pseudomonas spec., 16% Acinetobacter spec., 16% enterobacteria. In 3 patients, fungemia was observed. The antibiotic susceptibility profile was quite favorable in both, gram-positive and -negative bacteria: none of the gram-positive isolates was resistant to vancomycin, none of the Staphylococcus aureus isolates was resistant to oxacillin. All gram-negative bacteria were fully susceptible to ceftazidime, imipenem and ciprofloxacin.

CONCLUSION

Gram-positive bacteria account for 2/3 of all bacteremic episodes in pediatric oncology patients. Streptococcus viridans was the most important pathogen in hematological malignancies accounting for a significant, pathogen-specific morbidity.

Helicobacter pylori

Helicobacter pylori infection causes peptic ulcer disease, gastric adenocarcinoma, gastric lymphoma, and probably nonulcer dyspepsia. Although the prevalence of infection is declining over time, the organism still infects approximately one half of the world's population. Only a minority will ever suffer serious consequences from their infection. This article reviews current knowledge about H. pylori and presents some of the dilemmas surrounding clinical and public health approaches to this widespread pathogen.

[Invasive fungal infection in malignant hematologic diseases]

In patients with hematological malignancies invasive mycoses occur frequently. In this retrospective study autopsy and histopathology material of 171 patients with hematological malignancy who had died between 1994 and 1996 at the 1st Department of Internal Medicine (Hematology), St. László Hospital, Budapest was analysed. In cases with invasive fungal infection post mortem results were compared to clinical and microbiological data. Through the three years' period an invasive mycosis could be confirmed in 33 patients by autopsy. Aspergillosis occurred in 21, candidiasis in 11, other fungal infections in 2 cases, a double infection was seen in 1 patient. The incidence was 19.2% (in invasive candidiasis: 6.4%, in aspergillosis 12.2%). Invasive aspergillosis most frequently was seen in the lung (71%), while candidiasis occurred mainly in the intestinal tract (42%). Cultures for mycology were collected from the autopsy material of 9 patients, of which 8 gave positive results. A previous fungal colonisation results was confirmed in 23 patients, but based on colonisation conclusions rarely could be driven concerning the species causing invasive infection. Sensitivity of Aspergillus antigen and antibody tests was 45 and 50%, respectively. Predisposing factors for invasive aspergillosis and candidiasis were similar, except for duration of neutropenia (24 vs. 12 days, p < 0.004). The antifungal drug most frequently used was amphotericin B. We observed a persisting infection in invasive pulmonary aspergillosis and chronic disseminated candidiasis in spite of the administration of a cumulative dosis of 1-2 g. Most frequently Aspergillus infections--primarily that of the lung--can be seen. Presence of invasive mycoses can usually be confirmed in vivo, but an early diagnosis still remains unsolved.

What remaining questions regarding Helicobacter pylori and associated diseases should be addressed by future research? View from Europe

A variety of questions regarding Helicobacter pylori need to be addressed by future research. Further investigations are needed on the relationship between H. pylori and gastric cancer. In particular, the mechanism of the interaction between H. pylori infection and host genetic factors and dietary factors that lead to the cancer need to be unraveled. Also, the reversibility of cancer-associated abnormalities (e.g., hypochlorhydria, atrophy, and intestinal metaplasia) by eradication of H. pylori needs to be determined. Noninvasive means of identifying H. pylori-positive subjects at high risk of developing gastric cancer are required for such subjects to be targeted for eradication therapy. Further studies are also required on the interactions between H. pylori and proton pump inhibitor therapy that might predispose to cancer. There is considerable interest in the possibility of noninvasive H. pylori testing replacing endoscopy in determining management of nonelderly patients with uncomplicated dyspepsia unassociated with nonsteroidal anti-inflammatory drugs (NSAIDs). Randomized studies comparing endoscopy vs. noninvasive H. pylori testing in this situation are required with comprehensive outcome measures. Improvement in eradication therapy is required and will depend on the development of more effective and specific antibiotics and therapeutic vaccines. Wide-scale elimination of the infection will depend on preventing its spread from person to person. Achieving this will require further knowledge of its mode of transmission, particularly in childhood, and the development of prophylactic vaccines. Further studies are required to define the role of H. pylori infection in other diseases, including predisposition to enteric infection in the developing world as a result of H. pylori-induced chronic hypochlorhydria, nonulcer dyspepsia, pernicious anemia, atherosclerosis, and NSAID-related ulcer disease. Finally, we need to know whether H. pylori infection may be beneficial in certain circumstances and whether eradicating the infection may be disadvantageous to some subjects.

Helicobacter pylori and non-Helicobacter pylori bacterial flora in gastric mucosal and tumour specimens of patients with primary gastric lymphoma

There is an association between Helicobacter pylori (H. pylori) and gastric mucosa-associated lymphoid tissue (MALT) and MALT lymphoma. Histologically, mainly non-specific stains are used to detect H. pylori, such as haematoxylin-eosin (HE) or modified Giemsa (MG). In this study, both a MG and a specific immunohistochemical stain (IMM) for H. pylori (Dako B471) were performed on sequential slides of resected material containing tumour and non-tumorous gastric mucosa from patients with primary gastric lymphoma (n = 52). Special attention was paid to the presence of non-H. pylori bacterial flora diagnosed by a positive MG (according to form and localization) and a subsequently negative IMM. On all slides, bacterial density was scored semiquantitatively (grades 0, 1, 2, 3). In total, 32 (61.5%) patients were H. pylori positive using IMM and 34 (65.4%) were non-H. pylori positive using MG. In 24 out of the 34 patients, the non-H. pylori flora consisted mainly of cocci in combination with rods in 15 patients, mostly in minor quantities; in another 10 patients, high numbers of both cocci and different types of rods were present. Most non-H. pylori bacteria were localized superficially, although in 22 patients minor quantities of non-H. pylori were also seen in the glandular lumina. After all of the patients had been analysed, no differences in the density of H. pylori and of non-H. pylori flora were found. Only when comparing patients who had a small-cell lymphoma with those who had a large-cell lymphoma was a significantly higher density of H. pylori found in the corpus mucosa of large-cell lymphomas and a higher prevalence of non-H. pylori was found in tumours, in antrum or corpus, of patients with large-cell lymphomas. In conclusion, with joint evaluation using MG and a H. pylori-specific immunohistochemical stains, the proportion of H. pylori-positive gastric lymphoma patients was lower than in most previous studies but other bacteria were found in a relatively high proportion. The role of the non-H. pylori intragastric bacterial flora identified in this study has to be further elucidated in the aetiopathogenesis of primary gastric lymphoma.

Five-year follow-up study of saliva, mutans streptococci, lactobacilli and yeast counts in lymphoma patients

Twenty-two patients out of the 79 that were originally included were examined 5 years after beginning anticancer therapy for lymphomas. The patients' cumulative data on salivary flow rate, buffering capacity and acidogenic microbial counts were compared with respective data of 17 patients who died during the follow-up. Stimulated saliva samples had been taken at baseline and during the cytostatic treatment with combination chemotherapy, and 1 year and 5 years later. Chair-side kits were used at the hospital ward for the assessment of the study parameters. Mean saliva flow at baseline was 1.5 +/- 0.7 ml/min in the surviving group and 1.5 +/- 0.8 ml/min in the deceased. Salivary flow rates were not affected by the anticancer treatment and there was no statistically significant difference between the groups in this respect. A significant difference was observed between the groups in salivary buffering capacity values at baseline: only 32% of the survived had low buffering capacity in comparison to 69% of those who later died (P < 0.02). Buffering capacity values remained low in 50% of the surviving patients 5 years later. Higher mutans streptococci and lactobacilli counts were seen among the deceased than in the survived patients but mutans streptococci decreased significantly in both groups after the start of the anticancer therapy (P < 0.05). The number of positive yeast counts increased consistently during the chemotherapy in both groups, being higher in the survived when compared with the deceased patients. Yeast counts remained positive 5 years later in 73% of the survived patients, while the mean mutans streptococci and lactobacilli counts decreased below baseline values. The results showed that persistently high salivary microbial counts and low buffering capacity may be linked with poor prognosis.

Promotion by Helicobacter hepaticus-induced hepatitis of hepatic tumors initiated by N-nitrosodimethylamine in male A/JCr mice

A new murine Helicobacter species, Helicobacter hepaticus, infects the livers of mice, causing a progressive chronic active hepatitis culminating in hepatocellular tumors. To examine the role of chronic H. hepaticus infection in carcinogenesis, H. hepaticus-infected male infant mice of A/JCr strain were given a single i.p. dose of N-nitrosodimethylamine (NDMA). Noninfected A/J mice similarly treated with NDMA served as controls. The effect of hepatitis induced by H. hepaticus was studied for 64 wk. At 31-36 wk, the incidence of hepatocellular adenomas in infected mice was significantly higher than in noninfected mice (82 vs 52%; p = 0.05). The multiplicity of hepatocellular tumors was also significantly higher in infected mice compared to noninfected mice (3.2 +/- 0.09 vs 0.09 +/- 0.2; p = 0.03). At 51-64 wk, many (10/18) infected mice developed hepatocellular carcinomas while only 2 of 19 control mice developed such tumors (p = 0.005). Overexpression of cyclin D was observed in hepatocytes as well as adenomas induced by NDMA in H. hepaticus-infected mice, suggesting its role in inflammation, abnormal cell growth, and early neoplasia. High molecular weight keratins were highly expressed in hyperplastic oval cells in hepatitis and in liver tumors in mice with hepatitis, establishing a reliable marker for oval cells in formalin-fixed, paraffin-embedded tissue. Thus, chronic H. hepaticus infection significantly stimulated cyclin D expression, accelerated the development of liver tumors, increased the multiplicity of such lesions, and enhanced the progression of benign to malignant tumors.

Helicobacter pylori-associated gastroduodenal disease in childhood

Helicobacter pylori is responsible for one of the most frequently encountered infectious diseases worldwide. Infection due to H pylori can lead to the development of gastritis and peptic ulcer disease. The presence of H pylori in the human stomach also represents an increased risk for gastric cancer and gastric lymphoma. Recent epidemiologic data obtained in adults suggest that the actual colonization with H pylori is in fact determined by childhood factors. Therefore, the pediatric age group represents the ideal target population for studies concerning the pathogenesis and epidemiology of H pylori infection. This review addresses the spectrum of H pylori-associated gastroduodenal disease in childhood.

Synchronous mucosa-associated lymphoid tissue lymphoma and adenocarcinoma of the stomach

The development of simultaneous primary gastric lymphoma and carcinoma is a rare event for which a possible etiopathogenetic role for Helicobacter pylori (HP) recently has been postulated. We report a series of eight such cases diagnosed from 1980 to 1995. In two cases, both tumors arose in a gastric stump, at 26 and 34 years, respectively, after gastric resection for a duodenal ulcer. Grossly, the lymphoma and carcinoma formed a single lesion in four cases (collision tumor); they were separated in the other four cases. Histologically, all the lymphomas fit into the category of B-cell mucosa-associated lymphoid tissue lymphoma; six of them were low-grade lymphomas and two were low-grade lymphomas with a high-grade component. The adenocarcinomas were intestinal-type in four cases, diffuse in three, and mixed in one. Regarding the depth of infiltration, four carcinomas were early gastric cancers and four were advanced. All the collision tumors contained an early gastric cancer. Our observations confirmed the association of HP with gastric lymphoma and carcinoma in 4 cases. Spiral bacteria with the features of Helicobacter heilmannii were found in one case. The occurrence of two different tumors in a gastric stump, which has not been reported previously, suggests that postgastrectomy gastritis might contribute to the development of both gastric lymphoma and carcinoma.

Primary gastric lymphoma presenting with vitamin B12 deficiency and achlorhydria

Gastric lymphoma is an uncommon condition, usually presenting with epigastric pain and/or dyspepsia. There is now good evidence that infection with Helicobacter pylori (Hp) is etiologically important. We report here a case of primary gastric lymphoma presenting with vitamin B12 deficiency anemia and achlorhydria in which there was evidence of previous, but not current, infection with Hp. Vitamin B12 deficiency was proven to be due to intrinsic factor deficiency. To our knowledge, this condition has not previously been reported.

Mycobacterium haemophilum: microbiology and expanding clinical and geographic spectra of disease in humans

Reports of the association of Mycobacterium haemophilum with disease in humans have greatly increased. At least 64 cases have now been reported, with symptoms ranging from focal lesions to widespread, systemic disease. The organism is now known to cause primarily cutaneous and subcutaneous infection, septic arthritis, osteomyelitis, and pneumonitis in patients who are immunologically compromised and lymphadenitis in apparently immunocompetent children. Underlying conditions in the compromised patients have included AIDS; renal, bone marrow, and cardiac transplantation; lymphoma; rheumatoid arthritis; marrow hypoplasia; and Crohn's disease. Reports have originated from diverse geographic areas worldwide. The epidemiology of M. haemophilum remains poorly defined; there appears to be a genetic diversity between strains isolated from different regions. The organism is probably present in the environment, but recovery by sampling has not been successful. M. haemophilum has several unique traits, including predilection for lower temperatures (30 to 32 degrees C) and requirement for iron supplementation (ferric ammonium citrate or hemin). These may in the past have compromised recovery in the laboratory. Therapy has not been well elucidated, and the outcome appears to be influenced by the patient's underlying immunosuppression. The organisms are most susceptible to ciprofloxacin, clarithromycin, rifabutin, and rifampin. Timely diagnosis and therapy require communication between clinician and the laboratory.

Infections in haematological malignancies: an autopsy study of 72 cases

Autopsy material from 72 patients with haematological malignancies treated in India was reviewed. Thirty-seven patients (51%) had documented infections; 20 (27%) had bacterial infections, 14 of which were Gram-negative organisms (Pseudomonas species in 10); tuberculosis was present in 2 patients (2.7%). Twenty-one patients (29%) had systemic fungal infections; invasive pulmonary aspergillosis and gastrointestinal candidiasis were present in 10 patients each. Only 3 patients (4%) had viral infection, all of which were due to cytomegalovirus. Eleven patients (15%) had polymicrobial infections. No patient had any parasitic infection. Systemic fungal infections due to Aspergillus and Candida predominated, while Gram-negative bacterial infections were also common.

Infectious agents and environmental factors in lymphoid malignancies

A strong association was found to exist between patterns of lymphoid malignancies and socioeconomic status. B-cell lymphomas and T-acute lymphoblastic leukemia are much more prevalent in developing countries where the chances of acquiring infections especially at a younger age are high. B-cell precursor acute lymphatic leukemia, however, are much more prevalent in the Western world. Many infectious agents are associated with lymphatic malignancies. Epstein-Barr virus is involved in African Burkitt's lymphoma, human immunodeficiency virus-related Burkitt's lymphoma, lymphoproliferative syndrome post-transplantation, and Hodgkin's disease. Other infectious agents which may play a role in lymphoproliferative disorders are human immunodeficiency virus in acquired immune deficiency syndrome-associated lymphoma, human T-lymphotropic virus in adult T-cell lymphoma, Helicobacter pylori in mucosa-associated lymphoid tissue lymphoma, theileriosis in lymphoproliferative syndrome in cattle, Avian leukosis virus in chicken bursal lymphoma, and possibly a bacterial infection in immunoproliferative small intestine disease, potentially reversed by antibiotic therapy. The association between infectious agents and hematologic malignancies may be explained by the creation of large populations of activated cells followed by higher occurrences of 'genetic accidents'. This theory may be reinforced in at least some malignancies with the existence of viral proteins which either have complex relationships with key cellular gene products like p53 and Rb which have roles in cell cycle control, or share common motifs with bc1-2, therefore operating as anti-apoptotic elements. Whenever these genes are deranged, cell deoxysibonucleic acid repair or apoptosis are no longer possible, thereby creating a state of genome instability, increased acquisition of mistakes, and increased chances for malignant transformation.

Gastric lymphoma in Grampian Region: presentation, treatment and outcome

Forty cases of gastric lymphoma presenting in Grampian Region (1974-91) were reviewed to examine the effects of changing ideas in the fields of chemotherapy, gastric surgery and diagnostic techniques, as well as the impact of Helicobacter pylori. Presentation was non-specific, and the diagnosis was made pre-operatively in only 12 cases. Survival was related to tumour size, staging (Ann Arbor), and grade, with a crude 5-year survival of 49%. Helicobacter pylori was found in all specimens reviewed. Patients who underwent "potentially curative' surgery followed by adjuvant therapy had the best survival (85% at 5 years). There remains a need for larger studies to define the best treatment for this uncommon condition.

Diagnosis and posttreatment follow-up of Helicobacter pylori-positive gastric lymphoma of mucosa-associated lymphoid tissue: histology, polymerase chain reaction, or both?

The differential diagnosis between Helicobacter pylori (H pylori-associated chronic gastritis and low-grade B-cell gastric lymphoma of mucosa-associated lymphoid tissue (MALT) and the assessment of endoscopic biopsy specimens after treatment of lymphoma can be problematic. Although immunocytochemistry can be used to identify clonal B-cell populations, which are characteristic of MALT lymphoma, its application to small biopsy specimens and the subsequent interpretation can be difficult. The polymerase chain reaction (PCR) can detect clonal B-cell populations by analysis of the Ig heavy chain gene in routinely fixed paraffin-embedded material and might provide a useful tool in the assessment of these specimens. We have investigated the value of histology and PCR in the diagnosis of lymphoma and its followup in formalin-fixed paraffin-embedded gastric endoscopy biopsy specimens from 69 sequential patients selected on the basis of a dense mucosal lymphoid infiltrate associated with H pylori infection. Histologic evidence of MALT lymphoma was identified in 13 cases, 9 of which showed PCR-detected monoclonality. In 12 of 13 cases, H pylori was eradicated, and in 11 of 12 cases, histologic regression of the lymphoma followed. PCR evidence of monoclonality disappeared in 6 of 9 originally monoclonal cases. This was synchronous with histologic remission in 1 case, but lagged in the remaining 5 cases by up to 28 months. Two of the 3 of the 9 cases originally monoclonal by PCR that have not shown molecular regression have monoclonal-amplified products 17 and 24 months after negative histology. In 3 cases, the histology of the biopsies was considered indeterminate or discordant. In 1 of these cases, the histologic features were obscured by crush artefact. In a second case, there was molecular evidence of monoclonality in the absence of histologic features suggestive of lymphoma; this persisted after H pylori eradication. An additional single case originally diagnosed as reactive developed a PCR detectable clonal population 29 months after original evaluation in the absence of histologic features of lymphoma but in the presence of persistent H pylori infection. These findings suggest that the histologic assessment of gastric biopsies remains the method of choice for the diagnosis of lymphoma in gastric endoscopic biopsies with a dense mucosal lymphoid infiltrate. PCR provides a useful technique to support the diagnosis if clonal amplification products are found. The significance of PCR detected clonality in the absence of histologic evidence of lymphoma in uncertain but may represent a stage of tumor progression/regression when the clonal population is insufficient to be detected by conventional histology. This is supported by the evidence that PCR-detectable monoclonality can persist after treatment and the disappearance of histologically detectable lymphoma.

Clusters of lymphoma in ferrets

Cluster outbreaks of lymphoma and leukemia have been associated with viral infections in many species including humans, cattle, and cats. This study describes epidemiological, clinical, and pathological features of cluster outbreaks of lymphoma in multiferret households and examines and compares the Aleutian disease virus (ADV) and feline leukemia virus (FeLV) status of cases, ferrets at risk, and controls. Three ferret groups with 21 cases of histologically diagnosed lymphoma (12.6% cumulative incidence) and their cohabitants (n = 35) were examined and compared with three control groups (n = 52) of cohabitating ferrets without lymphoma. A familial distribution was observed in one group but most cases were not consanguinous. Ferrets greater than 3 years of age developed chronic disease in two of the groups and 2-year-old adults had acute disease in the remaining group. Lymphocytosis, splenomegaly, and lymphadenopathy were prominent features. Histologically, predominantly small noncleaved cell and polymorphous lymphoid lesions were observed. All of the ferrets with lymphoma that were tested for ADV and FeLV using serology or PCR were negative. The rate of ADV antibody among cases or ferrets at risk was not significantly different from controls. None of the cluster ferrets were seropositive for FeLV p27 antigen using a monoclonal ELISA. Infection with a novel ferret virus is suspected, but an etiological agent has not yet been identified.

DNA amplification for the in vitro detection of Candida albicans in head and neck squamous cell carcinomas

DNA was extracted from whole cells of Candida albicans and digested with HindIII restriction enzyme. After electrophoresis in a segment of the lane containing between 800 and 1200 base pairs (bp) of DNA fragments, a 1.1-kilobase (kb) fragment was found that hybridizes to biopsied tumor cells from head and neck squamous cell carcinomas (SCC). From the nucleotide sequence of the putative gene locus, primers were synthesized for use in a polymerase chain reaction (PCR) with DNA extracted from 18 SCC of the upper aerodigestive tract. After 30 cycles of amplification all tumors were found to contain sufficient amplified DNA to be detected in polyacrylamide or agarose gels. In contrast, template DNA from lymph nodes and malignant lymphomas failed to generate positive signals under these conditions. However, samples of DNA obtained from head and neck SCC cells in vitro, Candida glabrata, and Candida parapsilosis after PCR were found to contain homologous sequences. Application of this technique to head and neck SCC biopsies may help to identify quickly the presence of concurrent candidal species.

Bacterial infection as a cause of cancer

Bacterial infections traditionally have not been considered major causes of cancer. Recently, however, bacteria have been linked to cancer by two mechanisms: induction of chronic inflammation and production of carcinogenic bacterial metabolites. The most specific example of the inflammatory mechanism of carcinogenesis is Helicobacter pylori infection. H. pylori has been epidemiologically linked to adenocarcinoma of the distal stomach by its propensity to cause lifelong inflammation. This inflammation is in turn thought to cause cancer by inducing cell proliferation and production of mutagenic free radicals and N-nitroso compounds. H. pylori is the first bacterium to be termed a definite cause of cancer in humans by the International Agency for Research on Cancer. Mutagenic bacterial metabolites are also suspected to increase risk for cancer. This model is best exemplified in colon cancer. Bile salt metabolites increase colonic cell proliferation. Exogenous compounds such as rutin may be metabolized into mutagens by resident colonic flora. Moreover, Bacteroides species can produce fecapentaenes, potent in vitro mutagens, in relatively high concentrations. In vivo data on human carcinogenesis by bacterial metabolites, however, are inconsistent. Local bacterial infections may also predispose to nonnodal lymphomas, although the mechanisms for this are unknown. Gastric lymphomas and immunoproliferative small intestinal disease have been most strongly linked to underlying bacterial infection. Because bacterial infections can be cured with antibiotics, identification of bacterial causes of malignancy could have important implications for cancer prevention.

Malignant lymphomas induced by an Epstein-Barr virus-related herpesvirus from Macaca arctoides--a rabbit model

Animal models for Epstein-Barr virus (EBV) are restricted to some species of new-world monkeys which develop malignant lymphoid tumours or benign lymphoproliferative diseases after virus inoculation. Similar pathological features were induced in rabbits by the EBV-related herpesvirus of Macaca arctoides (HVMA). In this study 17 of 32 rabbits infected with varying amounts of HVMA produced from MAL-1 cells developed lymphoproliferative disorders. In 13 rabbits high-grade malignant lymphomas were detected, 4 rabbits revealed the histopathological feature of lymphoid hyperplasia. These lymphoproliferations were shown to be associated with HVMA by PCR and by the expression of EBV-like RNAs (EBER) in 14 and 10 cases, respectively. The homology in the polymerase gene region between DNA from EBV and HVMA, and from HVMA and the malignant tissue was found to be 94.8% and 100%, respectively. All the infected animals produced antibodies to antigens corresponding to early and late EBV proteins. By studying the HVMA expression in MAL-1 cells EBV-like proteins expressed in latency (EBNA1 and EBNA2) and in the lytic cycle (VCA, EA) were detected. Our findings suggested that HVMA caused a symptomatic infection in rabbits with pathological features that fit the conditions of an animal model suitable for testing antiviral drugs and vaccines against EBV.