Biomedical subjects

T Naab

Publications and source records attributed to T Naab.

8 recordsLinked to original sources

PubMed2001

Metastatic choriocarcinoma presenting as a bleeding duodenal ulcer.

We report a case of a young man with a rare disease, a choriocarcinoma of the gastrointestinal tract presenting as a common entity, a bleeding duodenal ulcer. Pathological findings and strongly positive immunostains of tissue specimens for beta human chorionic gonadotrophin confirmed the entire tumor to be a choriocarcinoma ruling out the possibility of an adenocarcinoma with focal components of choriocarcinoma or a beta human chorionic gonadotrophin producing adenocarcinoma. The pattern of tumor invasion in this case is more suggestive of metastatic than primary involvement of the gastrointestinal tract. The diagnosis of primary gastrointestinal choriocarcinoma is difficult because of the need to meticulously rule out the occurrence of a primary in other organs, which at times regresses spontaneously, a diagnosis made more difficult in this case in which no autopsy was performed.

Choriocarcinoma↗

PubMed2000

A method for establishing primary cultures of human gastric epithelial cells.

Long-term culture of human gastric epithelial cells has been difficult, and at present no normal human gastric epithelial cell lines are readily available. As part of our experiments to study pathogenesis of H. pylori, a bacterium that infects the stomach, we developed methods to culture normal human gastric epithelial cells. Primary cultures of human gastric epithelial cells can be established from gastric biopsies taken at upper G.I. endoscopy. Enzymatically isolated gastric epithelial-like cells are present in tight colonies on culture dishes within 24 hours of placing the cells in culture. Cells isolated stain positively for cytokeratin and produce neutral mucins, indicating that they are mucin secreting epithelial cells, consistent with gastric epithelial cells. Epithelial cells can be maintained up to 4 weeks in culture with evidence of DNA synthesis up through the first week of culture.

Biopsy↗

PubMed1999

Effects of Helicobacter pylori on proliferation of gastric epithelial cells in vitro.

OBJECTIVE: H. pylori infection of the gastric mucosa has been associated with an increase in gastric epithelial cell proliferation. However, in vitro adherence of H. pylori to gastric epithelial cells is associated with reduced cell proliferation. Reduction of epithelial cell proliferation may contribute to ulcer formation and delay ulcer healing. The following study was undertaken to elucidate the ability of cagA-positive and -negative strains to impede gastric epithelial cell proliferation. METHODS: A human gastric adenocarcinoma cell line (AGS) was overlaid with either cagA-positive or cagA-negative H. pylori strains suspended in cell culture medium. Proliferation of AGS cells was analyzed by performing direct cell counts and by measuring metabolism of a soluble tetrazolium compound (MTS), after exposure to H. pylori for 24 h. RESULTS: When compared with control cells cultured in medium alone, AGS cell proliferation was reduced by 45.6% and 28.5% due to exposure to cagA-negative and cagA-positive strains, respectively. When bacterial-induced cytotoxicity was assessed by measuring release of lactose dehydrogenase (LDH) into the culture medium, cagA-positive strains were shown to induce significantly more cytotoxicity than cagA-negative strains. CONCLUSIONS: These experiments demonstrate that H. pylori exposure to AGS cells significantly reduces cell proliferation. However, cagA-positive strains that induce more cell injury reduce cell proliferation to a lesser extent than cagA-negative strains. Persistent replication of gastric epithelial cells injured by exposure to cagA-positive strains may be partially responsible for the stronger association with gastric cancer in persons infected with cagA-positive H. pylori strains.

Antigens, Bacterial↗

PubMed1996

Increased incidence of second primary malignancy in patients with carcinoid tumors: case report and literature review.

There is an increased incidence of second noncarcinoid neoplasms in patients with carcinoid tumors. This article reports a case of a synchronous malignant ileal carcinoid tumor in a patient with an adenocarcinoma of the sigmoid colon. This report illustrates the increased association of carcinoid tumors with other gastrointestinal malignancies.

Adenocarcinoma, Mucinous↗

PubMed1996

Effects of sucralfate on vacuolating cytotoxin activity and adherence of Helicobacter pylori to human gastric epithelial cells.

Sucralfate inhibits activity of certain Helicobacter pylori enzymes, implying that this medication may limit gastric cell injury associated with H pylori infection. This study evaluates the ability of sucralfate and its two major structural components, sucrose octasulfate and aluminum hydroxide, to reduce the cytotoxic effects of H pylori and to inhibit binding of H pylori to human gastric epithelial cells. Experiments were performed using human gastric epithelial cells isolated from gastric biopsy tissue taken at upper gastrointestinal endoscopy. Primary cultures of human gastric epithelial cells, when exposed to broth-culture supernatant from a vacuolating cytotoxin-positive H pylori strain, were shown to form cytoplasmic vacuoles. Preexposing H pylori brothculture supernatant to sucralfate reduced vacuole formation in human gastric epithelial cells; however, preexposure of H pylori broth-culture supernatant to aluminum hydroxide or sucrose octasulfate did not reduce vacuolation in human gastric epithelial cells. H pylori binding to human gastric epithelial cells was significantly reduced when H pylori was exposed to sucralfate prior to incubating the bacterium with human gastric epithelial cells. These data show that sucralfate, but not its two major components, reduces the toxicity of an H pylori-produced cytotoxin (VacA) and decreases H pylori adherence to human gastric epithelial cells. This reduction in H pylori cytotoxicity may contribute to sucralfate's ulcerhealing properties and to the lower ulcer recurrence rates seen in patients treated with this medication.

Anti-Ulcer Agents↗

PubMed1993

Adherence of Helicobacter pylori to cultured human gastric epithelial cells.

Experiments were performed to demonstrate that adherence of Helicobacter pylori to gastric epithelial cells causes alterations in the cell cytoskeleton. H. pylori intimately attached to cultured human gastric epithelial cells on small cellular projections, while there was no intimate association of H. pylori with cultured human esophageal epithelial cells. Fluorescein-conjugated phalloidin staining of gastric epithelial cells showed that H. pylori adherence stimulated actin polymerization; this stimulation was not observed with esophageal cells. Also, this organism's selectivity for gastric mucosa was supported by rare binding of bacteria to esophageal epithelial cells and gastric fibroblasts.

Actins↗

PubMed1987

Intrapulmonary thymoma.

A 50-year-old man presented with a lung mass in the left upper lobe, which was shown by electron microscopy to be a thymoma. There was no evidence of a mediastinal mass. The lymphocytes of the tumor reacted with monoclonal antibody T101, a pan T-cell marker, and with OKT8. B1 and B2 surface antigens characteristic of B lymphocytes were not detected. Tumors of thymic epithelial cells completely covered by pleura without mediastinal involvement are rare.

Humans↗

PubMedDate not supplied

Testicular plasmacytoma in a patient with the acquired immunodeficiency syndrome.

Clinical, laboratory, and pathologic findings from a case of primary extramedullary plasmacytoma of the testis and sinuses in a patient with acquired immunodeficiency syndrome (AIDS) are presented. To our knowledge this is the first case in the English literature of a primary testicular plasmacytoma in an HIV-infected patient. The findings in this report and those of others confirm the difference in the pattern of plasma cell tumor (PCT) presentation in patients infected with AIDS from those in non-infected individuals, suggesting that these tumors should be considered in the differential diagnosis of AIDS-associated malignancies.

Acquired Immunodeficiency Syndrome↗