Lipid microdomains contribute to apoptosis-associated modifications of mitochondria in T cells.

Plasma membrane lipid microdomains have been considered as a sort of 'closed chamber', where several subcellular activities, including CD95/Fas-mediated proapoptotic signaling, take place. In this work we detected GD3 and GM3 gangliosides in isolated mitochondria from lymphoblastoid CEM cells. Moreover, we demonstrated the presence of microdomains in mitochondria by immunogold transmission electron microscopy. We also showed that GD3, the voltage-dependent anion channel-1 (VDAC-1) and the fission protein hFis1 are structural components of a multimolecular signaling complex, in which Bcl-2 family proteins (t-Bid and Bax) are recruited. The disruption of lipid microdomains in isolated mitochondria by methyl-beta-cyclodextrin prevented mitochondria depolarization induced by GD3 or t-Bid. Thus, mitochondrion appears as a subcompartmentalized organelle, in which microdomains may act as controllers of their apoptogenic programs, including fission-associated morphogenetic changes, megapore formation and function. These results disclose a new scenario in which mitochondria-associated lipid microdomains can act as regulators and catalysts of cell fate.

Selective rescue of early haematopoietic progenitors in Scl(-/-) mice by expressing Scl under the control of a stem cell enhancer.

The stem cell leukaemia gene (Scl) encodes a basic helix-loop-helix transcription factor with a pivotal role in both haematopoiesis and endothelial development. During mouse development, Scl is first expressed in extra-embryonic mesoderm, and is required for the generation of all haematopoietic lineages and normal yolk sac angiogenesis. Ectopic expression of Scl during zebrafish development specifies haemangioblast formation from early mesoderm. These results suggest that SCL is essential for establishing the transcriptional programme responsible for the formation of haematopoietic stem cells and have focused attention on the transcriptional regulation of Scl itself. Previous studies have identified a panel of Scl enhancers each of which directed expression to a subdomain of the normal Scl expression pattern. Among them, a 3' enhancer directed expression during development to vascular endothelium and haematopoietic progenitors but not to Ter119(+) erythroid cells. The expression in haematopoietic stem cells, however, remained undetermined. We demonstrate that this 3' enhancer directs lacZ expression in transgenic mice to most foetal and adult long-term repopulating haematopoietic stem cells, and therefore functions as a stem cell enhancer. Consistent with these results, expression in Scl(-/-) embryos of exogenous Scl driven by the stem cell enhancer rescued the formation of early haematopoietic progenitors and also resulted in normal yolk sac angiogenesis. By contrast, erythropoiesis remained markedly deficient in rescued embryos. This observation is consistent with the inactivity of the stem cell enhancer in erythroid cells and reveals an essential role for SCL during erythroid differentiation in vivo.

GD3 glycosphingolipid contributes to Fas-mediated apoptosis via association with ezrin cytoskeletal protein.

Efficiency of Fas-mediated apoptosis of lymphoid cells is regulated, among other means, by a mechanism involving its association with ezrin, a cytoskeletal protein belonging to the 4.1 family of proteins. In the present work, we provide evidence for a further molecule that associates to ezrin in Fas-triggered apoptosis, the disialoganglioside GD3. In fact, as an early event, GD3 redistributed in membrane-associated domains in uropods and co-localized with ezrin. Co-immunoprecipitation analyses confirmed this result, indicating a GD3-ezrin association. Altogether, these results are suggestive for a role of GD3 in Fas/ezrin-mediated apoptosis, supporting the view that uropods contain a multimolecular signaling complex involved in Fas-mediated apoptosis.

The transcriptional repressor CDP (Cutl1) is essential for epithelial cell differentiation of the lung and the hair follicle.

The mammalian Cutl1 gene codes for the CCAAT displacement protein (CDP), which has been implicated as a transcriptional repressor in diverse processes such as terminal differentiation, cell cycle progression, and the control of nuclear matrix attachment regions. To investigate the in vivo function of Cutl1, we have replaced the C-terminal Cut repeat 3 and homeodomain exons with an in-frame lacZ gene by targeted mutagenesis in the mouse. The CDP-lacZ fusion protein is retained in the cytoplasm and fails to repress gene transcription, indicating that the Cutl1(lacZ) allele corresponds to a null mutation. Cutl1 mutant mice on inbred genetic backgrounds are born at Mendelian frequency, but die shortly after birth because of retarded differentiation of the lung epithelia, which indicates an essential role of CDP in lung maturation. A less pronounced delay in lung development allows Cutl1 mutant mice on an outbred background to survive beyond birth. These mice are growth-retarded and develop an abnormal pelage because of disrupted hair follicle morphogenesis. The inner root sheath (IRS) is reduced, and the transcription of Sonic hedgehog and IRS-specific genes is deregulated in Cutl1 mutant hair follicles, consistent with the specific expression of Cutl1 in the progenitors and cell lineages of the IRS. These data implicate CDP in cell-lineage specification during hair follicle morphogenesis, which resembles the role of the related Cut protein in specifying cell fates during Drosophila development.

Expression of P-170 glycoprotein sensitizes lymphoblastoid CEM cells to mitochondria-mediated apoptosis.

Multidrug resistance caused by P-glycoprotein (P-170) is a phenomenon by which cells exposed to a single drug acquire resistance to other structurally and functionally unrelated drugs. This is a widespread phenomenon described in vivo in the management of infectious as well as non-infectious diseases. Several in vitro models have been developed in order to evaluate physiopathological properties of P-170. Among these are P-170-expressing variants of the human T-lymphoblastoid CEM cell line called VBL100. As a general rule, drug resistance normally results in resistance to apoptosis induction. By contrast, a paradoxical activity is exerted in this cell model by the cytokine tumour necrosis factor-alpha (TNF-alpha), which is capable of inducing apoptosis in P-170-expressing variants better than in wild-type (wt) cells. In the present study we partially address the mechanisms underlying this activity. In fact, the susceptibility of VBL100 cells to TNF-alpha appears to be specifically due to the depolarization of their mitochondrial membrane, a key factor for apoptotic induction. The same was observed with staurosporine, a specific mitochondrion-mediated proapoptotic chemical probe. Conversely, other proapoptotic stimuli, such as Fas/CD95 or the anti-cancer drug etoposide, did induce significant cell death in wild type cells only. Thus, schematically, mitochondrially dependent stimuli appeared to be more effective in VBL100-cell killing, while 'physiological' stimuli showed the opposite behaviour. Importantly, under steady-state conditions, VBL100 cells displayed per se a mitochondrial membrane hyperpolarization that appeared strictly related to their high susceptibility to specific apoptotic stimuli. In conclusion, the study of a well-established cell model such as that represented by the wt/VBL CEM lymphoid cell line seems to suggest that the multidrug resistance phenotype can specifically sensitize cells towards 'unphysiological', mitochondria-associated cell death cascade or, in the same fashion, it could shift cells from type I (mainly plasma membrane-associated) towards type II (mainly mitochondrial membrane-associated) phenotype.

N-Acetylcysteine counteracts erythrocyte alterations occurring in chronic obstructive pulmonary disease.

A key role has been proposed for reactive oxygen species (ROS) in chronic obstructive pulmonary disease (COPD). Aim of the present work was to evaluate possible implications of ROS in the integrity and function of the cell type mainly involved in oxygen uptake and delivery to the peripheral tissues: the erythrocyte. Red blood cells (RBCs) were thus collected from blood samples from COPD patients. Furthermore, blood samples from the same patients treated with the antioxidizing drug of widespread use in such disease i.e., N-acetylcysteine (NAC), were also considered. Morphometric and analytical cytology studies were then conducted. We report herein that: (i) alterations of RBC ultrastructure were detectable in RBCs from COPD patients, that (ii) relevant changes of spectrin cytoskeleton and glycophorin expression were also found and that (iii) NAC treatment was capable of significantly counteracting these changes. These results are consistent with a reappraisal of the role of RBCs in this disease.

Colonic disease in cirrhotic patients with portal hypertension: an endoscopic and clinical evaluation.

Fifty cirrhotic patients with portal hypertension but without colonic or systemic disease underwent lower gastrointestinal endoscopy in order to investigate the effects, if any, of portal hypertension on the colon. Fifty patients without liver or systemic disease, examined by colonoscopy because of irritable bowel syndrome in the same period served as controls. Rectosigmoid varices were observed in 34% of the cirrhotic patients and 2% of the controls. Hemorrhoids were observed in 70% of the cirrhotic patients and 48% of the controls. Multiple vascular-appearing lesions were found in 16% of the cirrhotic patients and 6% of the controls. Nonspecific inflammatory changes were noted in 10% of the cirrhotic patients and 4% of the controls. Simultaneous presence, in the same patient, of rectosigmoid varices, hemorrhoids, multiple vascular-appearing lesions, and nonspecific inflammatory changes, was observed in only five (10%) of the cirrhotic patients. We found polyps in 12% of the cirrhotic patients and 14% of the controls, and a malignant tumor in 4% of the cirrhotic patients. The patients with normal colonoscopic findings were 8% of the cirrhotic patients and 36% of the controls. All patients and controls were followed up for 1 year; there was no gastrointestinal hemorrhage among controls, whereas 34% of the cirrhotic patients had an upper gastrointestinal hemorrhage (88% from esophageal varices, 12% from the stomach) and 4% had a lower gastrointestinal hemorrhage (one from rectosigmoid varices and one from nonspecific inflammatory lesions). Colonic lesions were significantly more frequent in the cirrhotic patients (92%) than in the control group (64%); however, such lesions did not seem specific to the disease and were not statistically correlated with the degree of esophageal varices by Child's grading, the etiology of cirrhosis, or the bleeding risk from the lower gastrointestinal tract.

Evaluation of clinical patterns in ulcerative colitis: a long-term follow-up.

The aim of this prospective research was to compare, in a seven-year follow-up, the clinical outcome of ulcerative pancolitis with that of non-progressive ulcerative colitis. The activity of the disease was evaluated by a Clinical Activity Index and an Endoscopic Index. Of 112 cases of ulcerative colitis observed, 95 showed no change in extent and were studied as examples of non-progressive UC, and in this group the extension of the disease was: pancolitis in 19%, left-sided colitis in 39%, proctosigmoiditis in 17% and proctitis in 25%. A colectomy had to be performed in 5%. None of the enrolled cases developed a cancer during the follow-up. The patients with ulcerative pancolitis or left-sided colitis were treated with 5-ASA 1.6 g/day in a delayed-release formulation, while the cases with proctosigmoiditis or proctitis were treated with 5-ASA enemas 4 g/day. The cases with more than one relapse/year were 39%. The proportion of patients with only one relapse/year was 53%. The patients with steady remission for all the seven years of the trial were only 8%, but with a statistically significant difference between the groups with initial diagnosis of proctosigmoiditis or proctitis and the group with initial diagnosis of pancolitis or left-sided colitis (12% versus 5%). Among the cases with continuous remission, 37% showed colonic alterations, with an endoscopic score higher than 4 but a clinical score less than 6. Side-effects were observed in 6% patients but without treatment withdrawal. Non-progressive ulcerative colitis throughout the colon has a relatively good prognosis which seems to be independent of the location of the disease, even if we have found a statistically significant higher percentage of cases with steady remission among the patients with more distal disease.

Prevalence of hepatitis C virus genotypes in Italy.

Hepatitis C viruses (HCV) present in 110 Italian patients were characterized by genotype-specific PCRs. Among the 65 cases of community-acquired hepatitis, HCV genotype II was dominant (60%), followed by genotypes IV (15%), III (11%), and I (3%). Among the 45 hemophilia-associated cases, the distribution of the four HCV genotypes was markedly different: genotype I was the most prevalent (61%), followed by genotypes II (25%), III (4%), and IV (2%). Double infections were observed in eight patients. Two HCV remained unclassified. For the 45 community-acquired cases from which a liver biopsy was available, genotype II was associated with more severe liver damage than the other types.

Therapeutic effectiveness and tolerance of 5-aminosalicylic acid in short term treatment of patients with ulcerative colitis at a low or medium phase of activity.

The therapeutic effectiveness and tolerance of 5-aminosalicylic acid (5ASA), compared with Salazosulphapyridine (SASP) in treatment of ulcerative colitis have been evaluated in 86 patients with the disease at a low or medium phase of activity. After a treatment of six weeks, an improvement was noted in 63.6% (5ASA) and 61.3% (SASP) of these patients. However in no case was a complete remission of the disease observed on the basis of endoscopic inspection. In patients with pancolitis the improvement was lower (37.5% with 5ASA, 40% with SASP). The only side-effect was gastric intolerance, which occurred in 18.1% of the 5ASA and in 19% of the SASP patients. In conclusion we can assume that 5ASA and SASP largely overlap each other as regards both therapeutic effectiveness and occurrence of side-effects.

Albinismo en negroides. Primera descripcion para el Uruguay. Estudio genetico. / Albinism in negroids. First description to the Uruguay. Genetic study

Se describe la ocurrencia de albinismo oculo-cutaneo en una familia negroide de la ciudad de Treinta y Tres, Uruguay. Los propositi son un varon y su hermana, hijos de un matrimonio consanguineo. Se describe la genealogia, se estima el coeficiente de consanguinidad y se intenta clasificar a los casos en relacion a los diferentes tipos de albinismo