Pleural mesothelioma and lung cancer: the role of asbestos exposure and genetic variants in selected iron metabolism and inflammation genes.

Two of the major cancerous diseases associated with asbestos exposure are malignant pleural mesothelioma (MPM) and lung cancer (LC). In addition to asbestos exposure, genetic factors have been suggested to be associated with asbestos-related carcinogenesis and lung genotoxicity. While genetic factors involved in the susceptibility to MPM were reported, to date the influence of individual genetic variations on asbestos-related lung cancer risk is still poorly understood. Since inflammation and disruption of iron (Fe) homeostasis are hallmarks of asbestos exposure affecting the pulmonary tissue, this study aimed at investigating the association between Fe-metabolism and inflammasome gene variants and susceptibility to develop LC or MPM, by comparing an asbestos-exposed population affected by LC with an "asbestos-resistant exposed population". A retrospective approach similar to our previous autopsy-based pilot study was employed in a novel cohort of autoptic samples, thus giving us the possibility to corroborate previous findings obtained on MPM by repeating the analysis in a novel cohort of autoptic samples. The protective role of HEPH coding SNP was further confirmed. In addition, the two non-coding SNPs, either in FTH1 or in TF, emerged to exert a similar protective role in a new cohort of LC exposed individuals from the same geographic area of MPM subjects. No association was found between NLRP1 and NLRP3 polymorphisms with susceptibility to develop MPM and LC. Further research into a specific MPM and LC "genetic signature" may be needed to broaden our knowledge of the genetic landscape attributed to result in MPM and LC.

New insights on the role of gephyrin in regulating both phasic and tonic GABAergic inhibition in rat hippocampal neurons in culture.

Gephyrin is a tubulin-binding protein that acts as a scaffold for clustering glycine and GABA(A) receptors at postsynaptic sites. In this study, the role of gephyrin on GABA(A) receptor function was assessed at the post-translational level, using gephyrin-specific single chain antibody fragments (scFv-gephyrin). When expressed in cultured rat hippocampal neurons as a fusion protein containing a nuclear localization signal, scFv-gephyrin were able to remove endogenous gephyrin from GABA(A) receptor clusters. Immunocytochemical experiments revealed a significant reduction in the number of synaptic gamma2-subunit containing GABA(A) receptors and a significant decrease in the density of the GABAergic presynaptic marker vesicular GABA transporter (VGAT). These effects were associated with a slow down of the onset kinetics, a reduction in the amplitude and in the frequency of miniature inhibitory postsynaptic currents (mIPSCs). The quantitative analysis of current responses to ultrafast application of GABA suggested that changes in onset kinetics resulted from modifications in the microscopic gating of GABA(A) receptors and in particular from a reduced entry into the desensitized state. In addition, hampering gephyrin function with scFv-gephyrin induced a significant reduction in GABA(A) receptor-mediated tonic conductance. This effect was probably dependent on the decrease in GABAergic innervation and in GABA release from presynaptic nerve terminals. These results indicate that gephyrin is essential not only for maintaining synaptic GABA(A) receptor clusters in the right position but also for regulating both phasic and tonic inhibition.

Regulation of p53 activity in nuclear bodies by a specific PML isoform.

Covalent modification of the promyelocytic leukaemia protein (PML) by SUMO-1 is a prerequisite for the assembly of nuclear bodies (NBs), subnuclear structures disrupted in various human diseases and linked to transcriptional and growth control. Here we demonstrate that p53 is recruited into NBs by a specific PML isoform (PML3) or by coexpression of SUMO-1 and hUbc9. NB targeting depends on the direct association of p53, through its core domain, with a C-terminal region of PML3. The relocalization of p53 into NBs enhances p53 transactivation in a promoter-specific manner and affects cell survival. Our results indicate the existence of a cross-talk between PML- and p53-dependent growth suppression pathways, implying an important role for NBs and their resident proteins as modulators of p53 functions.

Rab17 regulates membrane trafficking through apical recycling endosomes in polarized epithelial cells.

A key feature of polarized epithelial cells is the ability to maintain the specific biochemical composition of the apical and basolateral plasma membrane domains while selectively allowing transport of proteins and lipids from one pole to the opposite by transcytosis. The small GTPase, rab17, a member of the rab family of regulators of intracellular transport, is specifically induced during cell polarization in the developing kidney. We here examined its intracellular distribution and function in both nonpolarized and polarized cells. By confocal immunofluorescence microscopy, rab17 colocalized with internalized transferrin in the perinuclear recycling endosome of BHK-21 cells. In polarized Eph4 cells, rab17 associated with the apical recycling endosome that has been implicated in recycling and transcytosis. The localization of rab17, therefore, strengthens the proposed homology between this compartment and the recycling endosome of nonpolarized cells. Basolateral to apical transport of two membrane-bound markers, the transferrin receptor and the FcLR 5-27 chimeric receptor, was specifically increased in Eph4 cells expressing rab17 mutants defective in either GTP binding or hydrolysis. Furthermore, the mutant proteins stimulated apical recycling of FcLR 5-27. These results support a role for rab17 in regulating traffic through the apical recycling endosome, suggesting a function in polarized sorting in epithelial cells.

HSV infection of polarized epithelial cells on filter supports: implications for transport assays and protein localization.

Epithelial cell lines can be grown on filter supports and form polarized monolayers with distinct basolateral and apical plasma membrane domains. This property has been extensively used in cell biology to investigate epithelial cell function. To date, a major limitation of this approach has been the difficulty of obtaining transient gene expression in polarized epithelia. Here we present an approach to overcome this problem using gene transfer into polarized epithelial cells grown on filters using a herpes virus-based vector. Recombinant genes are inserted into a defective HSV-1 plasmid and packaged with a replication-incompetent HSV-1 helper virus into virus particles which are used to infect the polarized epithelial cells grown on filters. The transepithelial resistance of the cells is not affected by the addition of virus, and there are no detectable cytopathic effects.

Effect of experimental cold pain stress on gastroesophageal junction.

The impact of stress on gastroesophageal reflux and antireflux mechanisms remains largely unexplored. To a major extent, reflux depends on a balance between gastroesophageal junction resistance to flow and gastric tone. We hypothesized that these two forces could be differently affected by stress, and to test the hypothesis we quantified in 10 healthy volunteers the effect of an acute stressful stimulus (cold pain) upon both gastroesophageal junction resistance (measured by a pneumatic resistometer) and gastric tone (measured by an electronic barostat). Such measurements were performed both under basal conditions and during stress stimulation (hand immersion in cold water for 5 min), on two separate days. The cardiovascular autonomic response was simultaneously monitored as changes in blood pressure and pulse rate. We found that, taken as a whole, cold stress significantly decreased gastroesophageal resistance (flow increase from 347 +/- 29 ml/min to 526 +/- 58 ml/min) as well as gastric tone (volume increase from 147 +/- 10 ml to 218 +/- 17 ml) (P < 0.02 for both). However, responses showed marked intra- and interindividual variation. Moreover, we found no relationship between changes in resistance to flow at the junction and either the cardiovascular autonomic response or the discomfort produced by cold stress. Changes in gastric tone were similarly unrelated to autonomic and perceptive responses. We conclude that in man experimental stress induced by cold pain tends to disrupt each of two opposite mechanisms that control gastroesophageal reflux: gastroesophageal resistance to flow and gastric tone. However, since both are decreased by stress, gastroesophageal function is largely maintained.

Effect of obesity on gastroesophageal resistance to flow in man.

Chronic (obesity) and acute intraabdominal pressure increases appear to favor gastroesophageal reflux, but the mechanism is not completely understood. We hypothesized that it could be due to an alteration in the resistance gradient between the stomach and the gastroesophageal junction, even increasing intragastric resistance above resistance at the gastroesophageal junction. Hence, we used a pneumatic resistometer to measure gastric and gastroesophageal resistance to flow in 11 lean healthy controls and eight morbidly obese individuals without gastroesophageal reflux disease. Resistance was quantified at rest and during acute intraabdominal pressure increases, both in the recumbent and sitting positions. We found that gastroesophageal junction resistance was higher than gastric resistance in lean as well as in obese subjects (P less than 0.001). In obese individuals both gastric and gastroesophageal junction resistance were increased (P less than 0.001), thus a normal gastric-gastroesophageal junction resistance gradient was maintained. Body position did not modify resistance. Acute increases in intraabdominal pressure decreased the gastric-gastroesophageal junction resistance gradient similarly in obese and lean subjects. We conclude that obesity by itself does not appear to predispose to gastroesophageal reflux, but it creates intraabdominal conditions that may favor reflux whenever the gastroesophageal barrier becomes weakened.

Effect of transcutaneous nerve stimulation on esophageal motility in patients with achalasia and scleroderma.

It has been suggested that low-frequency transcutaneous electric nerve stimulation (TENS) alleviates the dysphagia produced by achalasia and scleroderma of the esophagus. The present study was conducted to elucidate whether TENS treatment improves dysphagia because of changes it induces on esophageal motility. We studied nine achalasia patients before forceful dilatation of the cardias, nine achalasia patients after dilatation, and nine patients with scleroderma. High-frequency TENS was applied to the hand for 30 min while esophageal motility was monitored by manometry. In none of the groups did TENS produce any change in the basal tone of the lower esophageal sphincter, lower esophageal sphincter relaxation, or esophageal body wave amplitude. Low-frequency TENS, used in another seven untreated achalasia patients, also did not improve esophageal motility. Our data indicate that high- or low-frequency TENS does not induce detectable changes in esophageal motility in patients with achalasia or scleroderma.

Cigarette smoking increases gastric luminal prostaglandin F2 alpha and thromboxane B2 in healthy smokers.

Pentagastrin-stimulated gastric luminal prostaglandin E2 (PGE2), 6-keto-PGF1 alpha, PGF2 alpha and thromboxane B2 (TxB2) were measured using a second antibody solid-phase enzyme immunoassay before, during and after cigarette smoking in healthy smokers. Smoking significantly increased PGF2 alpha and TxB2 concentration and output; in contrast no significant changes were found for PGE2 and 6-keto-PGF1 alpha levels. In addition, cigarette smoking caused a significant reduction in gastric juice volume and acid output but did not alter intragastric acidity. These findings may suggest a possible role of prostanoids in the response of the stomach to cigarette smoking.

Diagnostic significance of anti-HBc IgM (RIA) in healthy HBsAg carriers and in chronic hepatitis B.

The diagnostic significance of IgM antibody against hepatitis B core antigen (anti-HBc) in healthy hepatitis B surface antigen (HBsAg) carriers and in subjects affected by chronic hepatitis B was evaluated. IgM anti-HBc was sought and found in all nine patients examined who were affected by acute HBsAg-positive hepatitis. It was also detected in 2 out of 18 patients with HBsAg-positive chronic persistent hepatitis and in 12 out of 42 patients affected by HBsAg-positive chronic active hepatitis. The absence of this marker was noted in all 26 HBsAg healthy carriers and in the subjects with HBsAg-positive cirrhosis. No relationship was found between the presence of IgM anti-HBc and the degree of inflammatory activity in the patients with HBsAg-positive chronic active hepatitis. A correlation was not found between the presence of IgM anti-HBc and the presence of hepatitis B e antigen (HBeAg) in the same patients. These data show that the absence of IgM anti-HBc may be useful in identifying healthy carriers of HBsAg. The presence of this antibody may be a suitable indication of acute HBsAg-positive hepatitis. In patients with chronic active hepatitis B the presence of IgM anti-HBc cannot be used as diagnostic tool in predicting the severity of liver disease.