Increased excitability in tat-transgenic mice: role of tat in HIV-related neurological disorders.

HIV-1 associated neurocognitive disorders (HAND) are a major complication of HIV-1 infection. The mechanism(s) underlying HAND are not completely understood but, based on in vitro studies, the HIV-1 Tat protein may play an important role. In this study, the effect of prolonged exposure to endogenously produced Tat in the brain was investigated using a tat-transgenic (TT) mouse model constitutively expressing the HIV-1 tat gene. We found that stimulus-evoked glutamate exocytosis in the hippocampus and cortex was significantly increased in TT as compared with wild-type control (CC) mice, while GABA exocytosis was unchanged in the hippocampus and decreased in the cortex. This suggests that Tat generates a latent hyper-excitability state, which favors the detrimental effects of neurotoxic and/or excitotoxic agents. To challenge this idea, TT mice were tested for susceptibility to kainate-induced seizures and neurodegeneration, and found to exhibit significantly greater responses to the convulsant agent than CC mice. These results support the concept that constitutive expression of tat in the brain generates a latent excitatory state, which may increase the negative effects of damaging insults. These events may play a key role in the development of HAND.

Differential effects of Helicobacter pylori eradication on oxidative DNA damage at the gastroesophageal junction and at the gastric antrum.

BACKGROUND AND AIM: Helicobacter pylori-associated gastritis causes accumulation of reactive oxygen species in the mucosal compartment. This prospective study evaluates DNA oxidative damage in biopsy samples obtained from both the antrum and the gastroesophageal junction (GEJ) before and after H. pylori eradication. PATIENTS AND METHODS: Thirty-two consecutive H. pylori-positive patients underwent endoscopy with multiple biopsy sampling (i.e., antrum, incisura angularis, fundus, and cardia at the GEJ). After H. pylori eradication, 32 patients underwent a checkup endoscopy (mean interval, 5.7 months); in a subgroup of 13 subjects, a third endoscopy procedure was also performed (mean interval, 18 months). Additional biopsy samples (two from the antrum and two from the GEJ) were used to assess 8-hydroxydeoxyguanosine (8OHdG) levels using both high-pressure liquid chromatography with electrochemical detector and ELISA. RESULTS: In the antral compartment, no significant modifications of 8OHdG levels were assessed after H. pylori eradication. Conversely, following eradication, 8OHdG levels significantly increased (high-pressure liquid chromatography with electrochemical detector, P = 0.04; ELISA method, P = 0.05) in biopsy samples taken from the GEJ, and a further increase was documented in the subgroup of patients who underwent a third endoscopy (P = 0.01). The increasing trend was more relevant in patients in whom H. pylori-cagA-positive strains were eradicated and in those affected by hiatal hernia. CONCLUSIONS: The levels of DNA adducts in the antral mucosa are not modified by H. pylori eradication; conversely, H. pylori eradication significantly increases the oxidative adducts at the GEJ. The clinical and biological importance of this situation and whether and how it relates to a higher risk of precancerous lesions is open to debate.

Accelerated CCl4-induced liver fibrosis in Hjv-/- mice, associated with an oxidative burst and precocious profibrogenic gene expression.

Hereditary hemochromatosis is commonly associated with liver fibrosis. Likewise, hepatic iron overload secondary to chronic liver diseases aggravates liver injury. To uncover underlying molecular mechanisms, hemochromatotic hemojuvelin knockout (Hjv-/-) mice and wild type (wt) controls were intoxicated with CCl(4). Hjv-/- mice developed earlier (by 2-4 weeks) and more acute liver damage, reflected in dramatic levels of serum transaminases and ferritin and the development of severe coagulative necrosis and fibrosis. These responses were associated with an oxidative burst and early upregulation of mRNAs encoding α1-(I)-collagen, the profibrogenic cytokines TGF-ß1, endothelin-1 and PDGF and, notably, the iron-regulatory hormone hepcidin. Hence, CCl4-induced liver fibrogenesis was exacerbated and progressed precociously in Hjv-/- animals. Even though livers of naïve Hjv-/- mice were devoid of apparent pathology, they exhibited oxidative stress and immunoreactivity towards α-SMA antibodies, a marker of hepatic stellate cells activation. Furthermore, they expressed significantly higher (2-3 fold vs. wt, p<0.05) levels of α1-(I)-collagen, TGF-ß1, endothelin-1 and PDGF mRNAs, indicative of early fibrogenesis. Our data suggest that hepatic iron overload in parenchymal cells promotes oxidative stress and triggers premature profibrogenic gene expression, contributing to accelerated onset and precipitous progression of liver fibrogenesis.

Microsatellite instability and hMLH1 and hMSH2 expression in renal tumors.

Defects in the function of mismatch repair (MMR) genes result in genetic instability, a common feature of malignant progression. This study was conducted to determine the frequency of genetic instability [defined as microsatellite instability (MSI)] and to evaluate the sensitivity/specificity of immunohistochemistry in predicting the deficiency in MMR genes in renal cortical tumors. A total of 51 surgically-resected renal tumors (27 clear cell, 10 papillary, 5 chromophobe carcinomas and 9 oncocytomas) were studied. We also analyzed the correlation with clinicopathological parameters, the MSI status (assessed by using 5 microsatellite markers: D2S123, D11S904, D3S1621, D3S1683 and BAT26), and the immunohistochemical expression of 2 major MMR genes [the human mutL homolog 1 (hMLH1) and the human mutS homolog 2 (hMSH2)]. Sixteen cases (31.4%) showed MSI: Three (5.9%) demonstrated a high level of MSI, 11 (21.6%) demonstrated a low level of MSI, 2 (3.9%) presented with a loss of heterozygosity, and the remaining 35 (68.6%) exhibited microsatellite stability. The loss of hMLH1 and hMSH2 immunohistochemical expressions was observed in 5/51 (9.8%) and 9/51 (17.6%) cases, respectively. The complete absence of both hMLH1 and hMSH2 immunohistochemical expressions was observed only in the 3 cases with a high level of MSI. This study showed that defects in MMR genes are involved in renal carcinogenesis and correlate with the occurrence of MSI.

Expression of p53, p16INK4A, pRb, p21WAF1/CIP1, p27KIP1, cyclin D1, Ki-67 and HPV DNA in sinonasal endophytic Schneiderian (inverted) papilloma.

CONCLUSIONS: Human papilloma virus (HPV) was associated with sinonasal inverted papilloma (SIP) in 14/20 (70%) patients with a prevalence of HPV 6/11; alterations of the cell cycle proteins were statistically significant. OBJECTIVES: We investigated SIPs relationships between HPV infection and aberrant expression of cell cycle proteins. MATERIALS AND METHODS: Twenty SIPs were evaluated for p53, p16(INK4a), pRb, p21(WAF1), p27(Kip1), cyclin D1 and Ki-67 expression by immunohistochemistry. HPV was investigated by polymerase chain reaction (PCR). RESULTS: HPV DNA was detected in 14/20 patients with inverted papillomas (IPs) (70%). The majority of tumours showed strong p16, p21, p27, pRb and cyclin D1 staining and little or no p53 expression. Tumours harbouring dysplasia were significantly more likely to be p53-positive and exhibit up-regulated p21 and p27, and showed altered intensity and distribution of reactive cells into and through the epithelium. Dysplastic epithelium was strongly reactive for p16 and the MIB 1 labelling index was almost 20%. These findings were associated with expression of p53 in the same zones. Comparing the p53 reactivity with the presence of HPV DNA, SIPs were stratified as follows: HPV + p53-, 12 (63.15%); HPV + p53+, 2 (10.52%); HPV - p53+, 3 (15.78%) and HPV - p53-, 2 (10.52%). Statistical analysis showed that HPV presence correlated with p53-positive immunostaining (p=0.045).

Diffuse intra-abdominal clear cell myomelanocytic tumor: report of an unusual presentation of "PEComatosis" simulating peritoneal mesothelioma.

We report a case of diffuse myomelanocytic tumor of the peritoneum that simulates, clinically and instrumentally, a malignant mesothelioma. The patient was a 70-year-old woman with a history of ancient hysterectomy for fibroids, who presented with abdominal discomfort. Exploratory laparotomy revealed diffuse encasing of the peritonealized organs by a thin, fleshy, gray-white tissue rind. Scattered tumor masses were present as well. A dominant lesion measuring 6 cm in larger size was resected from the pelvis. Histological examination revealed a tumor composed of epithelioid and spindle cells, exhibiting either a clear or slightly eosinophilic cytoplasm and a mild to moderate nuclear pleomorphism. Focal areas of necrosis could be documented. Immunohistochemically, tumor cells were positive for HMB45, melan-A, and smooth muscle actin, but negative for other antibodies, including epithelial markers, desmin, and S100 protein. We believe that this case represents an example of myomelanocytic tumor of uncertain biologic potential, a member of the recently devised perivascular epithelioid cell tumors (PEComa), with an unusual presentation simulating a diffuse mesothelial neoplasm. The origin of this particular lesion is briefly discussed in light of the recent literature published on the subject.

Helicobacter pylori CagA status, mucosal oxidative damage and gastritis phenotype: a potential pathway to cancer?

BACKGROUND: Oxidative DNA damage is associated with Helicobacter pylori infection, atrophy and intestinal metaplasia. H. pylori-cagA-positive strains are associated with the highest risk of gastric cancer. AIMS: To ascertain whether cagA-positive H. pylori infection correlates with higher concentrations of 8OHdG and the presence of precancerous changes. PATIENTS AND METHODS: 118 patients were studied (65M/53F, age 61 +/- 14 years). Twelve were H. pylori-negative. Among the H. pylori-positive patients, 34 were cagA-positive and 40 were cagA negative. In 32 patients H. pylori had been eradicated at least 6 months before endoscopic sampling. The phenotype of the gastritis (atrophic compared with nonatrophic, with and without intestinal metaplasia) was scored in biopsy samples obtained from the antrum, corpus, and angularis incisura. In antral biopsy samples, 8-hydroxydeoxyguanosine was assessed by HPLC (electrochemical detector). CagA status was determined by PCR. RESULTS: The highest scores for both mononuclear inflammation and activity of gastritis were significantly associated with cagA status (p = 0.036 antrum and p = 0.02 corpus). cagA-positive infection significantly correlated with a higher prevalence of atrophic-metaplastic lesions (p = 0.04). cagA-positive patients had higher 8-hydroxydeoxyguanosine levels than both cagA-negative and H. pylori-negative cases (p = 0.01). The 8-hydroxydeoxyguanosine levels were significantly higher in multifocal atrophic gastritis (p = 0.04). The odds ratio for cagA-positive patients having 8OHdG levels above a cut-off calculated on the basis of the ROC curves were 7.12, overall, reaching 11.25 when only patients younger than 50 were considered. CONCLUSIONS: cagA-positive patients were characterized: first, for higher scores for gastritis, activity and atrophic and metaplastic lesions; and second for greater oxidative DNA damage overall, at younger age and in the presence of multifocal atrophy. This setting may represent a cancer-prone biological context.

Granular cell tumor of the intrapancreatic common bile duct: one case report and review of the literature.

A granular cell tumor (GCT) in a 39-year-old white man is reported. It was localized in the intrapancreatic part of the common bile duct and caused obstruction of the bile downflow. The patient underwent radical surgical procedures because a malignant tumor was clinically suspected. Macroscopically, the tumor appeared as a duct stricture caused by diffuse infiltration of neoplastic cells in the walls. In the cytoplasm smaller and larger PAS-positive granules were present and constantly reactive to S-100 and NSE antibodies. Ultrastructurally, cytoplasmic granules appeared as membrane-bound vacuoles of variable size and shape containing debris, disrupted mitochondria, and myelin figures. No basal lamina around cell cytoplasm was observed. GCTs are relatively uncommon soft tissue tumors usually presenting in the skin and subcutaneous tissues or tongue. The prognosis in any location is quite good, but very rare malignant GCTs (1-2%) are documented. Complete excision reduces the risk of recurrence. Accurate operative diagnosis seems to be critical when the tumors are located in the intrapancreatic common bile duct as in this reported case. Gastro-pancreatico-duodenectomy is too radical a procedure for such a benign lesion and additional assessments and investigations are recommanded before such an extensive radical surgery.