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Biomedical subjects

A Beretta

Publications and source records attributed to A Beretta.

At least 19 recordsLinked to original sources
PubMed2001

Bub3 interaction with Mad2, Mad3 and Cdc20 is mediated by WD40 repeats and does not require intact kinetochores.

The kinetochore checkpoint pathway, involving the Mad1, Mad2, Mad3, Bub1, Bub3 and Mps1 proteins, prevents anaphase entry and mitotic exit by inhibiting the anaphase promoting complex activator Cdc20 in response to monopolar attachment of sister kinetochores to spindle fibres. We show here that Cdc20, which had previously been shown to interact physically with Mad2 and Mad3, associates also with Bub3 and association is up-regulated upon checkpoint activation. Moreover, co-fractionation experiments suggest that Mad2, Mad3 and Bub3 may be concomitantly present in protein complexes with Cdc20. Formation of the Bub3-Cdc20 complex requires all kinetochore checkpoint proteins but, surprisingly, not intact kinetochores. Conversely, point mutations altering the conserved WD40 motifs of Bub3, which might be involved in the formation of a beta-propeller fold devoted to protein-protein interactions, disrupt its association with Mad2, Mad3 and Cdc20, as well as proper checkpoint response. We suggest that Bub3 could serve as a platform for interactions between kinetochore checkpoint proteins, and its association with Mad2, Mad3 and Cdc20 might be instrumental for checkpoint activation.

Amino Acid Motifs↗
PubMed2001

Antibodies to C-C chemokine receptor 5 in normal human IgG block infection of macrophages and lymphocytes with primary R5-tropic strains of HIV-1.

In the present study, we demonstrate that normal human IgG for therapeutic use (i.v. Ig) contains natural Abs directed against the CCR5 coreceptor for HIV-1. Abs to CCR5 were isolated from i.v. Ig using an affinity matrix consisting of a synthetic peptide corresponding to the N-terminus of CCR5 coupled to Sepharose. Natural anti-CCR5 Abs inhibited the binding of RANTES to macrophages, demonstrating their interaction with the coreceptor of R5-tropic HIV-1. Affinity-purified anti-CCR5 Ig further inhibited infection of lymphocytes and monocytes/macrophages with primary and laboratory-adapted strains of HIV-1, but did not inhibit infection with X4-tropic HIV. Our results suggest that anti-CCR5 Abs from healthy immunocompetent donors may be suitable for development of novel passive immunotherapy regimens in specific clinical settings in HIV infection.

Animals↗
PubMed2001

The effects of scrambling on Spanish and Korean agrammatic interpretation: why linear models fail and structural models survive.

Several models of comprehension deficits in agrammatic aphasia rely heavily on linear considerations in the assignment of thematic roles to structural positions (e.g., the Trace-Deletion Hypothesis, the Mapping Hypothesis, and the Argument-Linking Hypothesis). These accounts predict that constructions in languages with rules that affect syntactic structure but preserve relative linear order should be unimpaired. Other models [e.g., the Double-Dependency Hypothesis, (DDH)] do not resort to linearity but are purely structural in conception and therefore should be immune to word-order effects. We tested linear and nonlinear accounts with scrambling structures in Korean and topicalization structures in Spanish. The results are very clear. The (nonlinear) DDH is entirely compatible with the evidence, but the linear accounts are not.

Adult↗
PubMed2001

Role of the kinetochore protein Ndc10 in mitotic checkpoint activation in Saccharomyces cerevisiae.

Mitotic checkpoints delay cell cycle progression in response to alterations in the mitotic apparatus, thus ensuring correct chromosome segregation. While improper spindle orientation activates the Bub2/Bfa1-dependent checkpoint in budding yeast, delaying exit from mitosis, lack of bipolar kinetochore-microtubule attachment activates a signal transduction cascade that prevents both anaphase onset and exit from mitosis by inhibiting the Cdc20/APC (Anaphase Promoting Complex)-mediated proteolysis of securin and inactivation of mitotic cyclin-dependent kinases (CDKs), respectively. Proteolysis of the securin Pdsl is necessary to liberate the separase Esp1, which then triggers sister chromatid separation, whereas inactivation of mitotic CDKs is a prerequisite for exit from mitosis and for starting a new round of DNA replication in the next cell cycle. In budding yeast, this latter checkpoint response involves the proteins Mad1, 2, 3, Bub1 and Bub3, whose vertebrate counterparts localize to unattached kinetochores. Mutations that alter other kinetochore proteins result in mitotic checkpoint activation, while the ndc10-1 mutation not only impairs kinetochore function, but also disrupts the checkpoint response, indicating a role for Ndc10 in this process. Here we present evidence that Ndc10 is not part of the Bub2/Bfa1-dependent pathway, and its role in the checkpoint response might also be different from that of the other Mad and Bub proteins. Indeed, Ndc10, unlike other mitotic checkpoint proteins, is not required for the mitotic block induced by overexpression of the Mpsl protein kinase, which is implicated in mitotic checkpoint control. Furthermore, the delay in mitotic exit caused by non-degradable Pds1, which does not require Mad and Bub proteins, depends on Ndc10 function. We propose that a pathway involving Ndc10 might monitor defects in the mitotic apparatus independently of the Mad and Bub proteins. Since the Espl separase is required for exit from mitosis in both ndc10-1 and nocodazole-treated mad2delta cells, the two signal transduction cascades might ultimately converge on the inactivation of Esp1.

Cell Cycle↗
PubMed2001

Insulin receptor antibodies inhibit insulin uptake by the liver: in vivo 123I-insulin scintigraphic scanning and in vitro characterization in autoimmune hypoglycemia.

BACKGROUND: Insulin receptor antibodies can induce severe hypoglycemia or insulin resistance in rare autoimmune syndromes. In vitro properties of these antibodies occasionally explain the clinical features of the syndrome, but direct evidence of their in vivo activity is poor. We studied a 58-year-old male with rheumatoid arthritis who presented with hypoglycemic coma. METHODS AND RESULTS: Antibodies were detected by inhibition of 125I-insulin binding to human insulin receptor-3T3 cells by the patient's serum. By immunofluorescence, they were immunoglobulin G of all four subclasses, immunoprecipitated insulin receptors from biotin-labeled cells, and triggered phosphorylation of the beta subunit of the insulin receptor. Insulin binding on the patient's red blood cells was markedly reduced. A biodistribution study after intravenous 123I-Tyr A14 insulin showed a marked inhibition of tracer uptake by the liver, reaching 10% of the injected dose (controls, mean +/- SD, 21.1 +/- 1.7%; n = 10). Time activity curves generated on the liver and on the heart were parallel, with a T1/2 of 11.5 minutes for both, suggesting that no specific uptake occurred in the liver, where tracer activity represented only the blood pool. Clearance of insulin from the blood was indeed slower than in controls and mainly occurred through the kidneys. Analysis of plasma 123I-insulin immunoreactivity and trichloroacetic acid precipitate showed that insulin degradation did not occur as in normal controls. CONCLUSIONS: In this patient with hypoglycemic syndrome, insulin receptor antibodies with in vitro insulin-like activity are capable of blocking in vivo the access of insulin to the liver receptor compartment, as directly demonstrated by the markedly altered biodistribution of intravenously injected 123I-insulin.

3T3 Cells↗
PubMed2000

Anti-cell antibodies in exposed seronegative individuals with HIV type 1-neutralizing activity.

Despite repeated exposures to HIV-1, some individuals remain seronegative. This study reports that sera from a fraction of exposed seronegative (ESN) subjects showed HIV-neutralizing activity; 5 of 17 ESN sera and none of 17 controls neutralized two different HIV-1 primary isolates (range of neutralizing titers: 1/20 to 1/60). The neutralizing activity was associated with the IgG fraction of 4 of 4 neutralizing ESN sera. Moreover, in 11 of 17 and 9 of 17 ESN sera (but none of the control sera) we found antibodies against HLA class I and CD4, respectively. One of the ESN sera (EU22) neutralized efficiently the primary virus derived from the seropositive partner and showed a good broadly cross-reactive neutralization. Immunoadsorption of two IgG fractions from EU19 and EU22 on peripheral blood mononuclear cells (PBMC) removed virus-neutralizing antibodies. The correlations between the ESN status and neutralizing activity (p<0.05), anti-HLA antibodies (p<0.0002), and anti-CD4 antibodies (p<0.001) were statistically significant. However, there was no statistically significant correlation between neutralizing activity and either anti-HLA or anti-CD4 antibodies. It can therefore be said that exposure to HIV-1 without seroconversion is, in some individuals, associated with HIV-neutralizing antibodies (not directed against viral antigens) and/or with anti-cell autoantibodies, which are possibly specific for cellular antigens involved in the infection/entry process.

Autoantibodies↗
PubMed2000

Hepatic amyloidosis with light chain deposition disease. A rare association.

Monoclonal immunoglobulin deposition diseases are due to pathological protein deposition in various tissues and organs. Protein deposits may be found in a single tissue or systemically and the organs most frequently involved are kidney, heart, peripheral nerves and the liver. Depending on the pattern of the deposits and the type of immunoglobulin, these diseases are distinguished as primary amyloidosis, light chain deposition disease. Differential diagnosis is made in tissue specimens: microscopically by the identification of positive Congo red staining of the deposits, by immunohistochemical demonstration of proteins reacting with light chain (lambda or kappa) antisera or by recognition of fibrillar structures on electron microscopy. We report an unusual case of light chain deposition disease associated with amyloidosis, where hepatomegaly was the presenting manifestation and liver failure the cause of death, without any kidney involvement.

Amyloidosis↗
PubMed2000

Genetic aspects in sarcoidosis.

Sarcoidosis is an immune-mediated, multiorgan, granulomatous disorder thought to be triggered by an intricate combination of environmental and genetic factors. Two robust lines of evidence support the hypothesis of a genetic component in the pathogenesis of sarcoidosis: racial variation in its epidemiology and familial clustering of cases. The relationship between epidemiology and environmental factors affecting variations in sarcoidosis incidence/prevalence and presentation are reviewed, as well as strategies to be pursued in the search for susceptibility genes for the disorder. Pathogenic processes leading to sarcoid granuloma formation and maintenance have prompted investigators interested in the genetics of sarcoidosis to focus mainly on major histocompatibility complex genes, and indeed a remarkable amount of data has been accumulated during the last two decades. Whilst in contrast with some autoimmune disorders a clear association between human leukocyte antigen (HLA) and sarcoidosis is still a controversial issue, there is, however, a general agreement that some HLA genes are related to phenotypic variations of the disease. Some genetic investigators have focused on T-cell receptor genes, immunoglobulin genes, angiotensin converting enzyme gene, chemokine genes and others. From a review of studies performed in different racial and ethnic groups, a reasonable suggestion arises that genetic factors are the major determinant in the racial variations in the epidemiology of the disorder. This assumption is, however, so far limited by lack of studies considering both genetic and environmental factors simultaneously.

Environmental Exposure↗
PubMed2000

Increased frequency of CFTR gene mutations in sarcoidosis: a case/control association study.

A complete screening of the CFTR gene by DGGE and DNA sequencing was performed in patients with sarcoidosis. In 8/26 cases, missense and splicing CFTR gene mutations were found, a significant difference over controls (9/89) from the same population (P = 0.014). The odds ratio for a person with a CFTR gene mutation to develop the disease is 3.95 (1.18 < OR < 13.26). Seven different CFTR gene mutations were observed: R75Q, R347P, 621 + 3 A/G, 1898 + 3 A/G, L997F, G1069R, and a novel mutation which was detected in this study, I991V. R75Q mutation was present in 3/26 patients, a significant increase (P = 0. 01) in cases over controls, indicating its preferential association with sarcoidosis. A trend towards disease progression was observed in patients with CFTR gene mutations compared to patients without mutations. These data suggest that CFTR gene mutations predispose to the development of sarcoidosis.

Adult↗
PubMed1999

Enhanced HIV infectivity and changes in GP120 conformation associated with viral incorporation of human leucocyte antigen class I molecules.

BACKGROUND: Assembly of human immunodeficiency virus type 1 (HIV-1) occurs at the level of the plasma membrane of the host cell. During this process HIV incorporates significant quantities of cell surface-derived molecules into its lipid bilayer including human leucocyte antigen (HLA) class I and II, intercellular adhesion molecule-1 and lymphocyte function antigen-1. Several studies indicate that virion-bound host-cell-derived molecules are functional and affect the biological properties of HIV-1. Virion-associated HLA class II and intercellular adhesion molecule-1 enhance the infectivity of T-cell line-adapted (TCLA) viruses. No role for virion-associated HLA class I molecules has yet been identified. OBJECTIVE: To investigate the role of HLA class I molecules in HIV replication and infectivity. METHODS: HLA class I negative human cells lines transfected with the HLA Cw4 gene were infected with different TCLA viruses as well as primary X4 isolates. The infectivity of HLA Cw4 positive and negative viruses was determined on indicator cell lines and on phytohaemagglutinin-activated peripheral blood mononuclear cells. An entry polymerase chain reaction assay was used to determine differences in entry-competence of Cw4 positive and negative viruses. The expression of selected gp120 epitopes on native Env molecules derived from Cw4 positive and negative viruses was determined by a monoclonal antibody-based enzyme-linked immunosorbent assay. Immunoprecipitation experiments were performed to investigate the presence of gp120/HLA Cw4 complexes. Neutralization assays determined the differences in susceptibility to neutralization between HLA Cw4 negative and positive viruses. RESULTS AND CONCLUSIONS: The infectivity of primary HIV-1 X4 isolates and of TCLA viruses is increased upon viral incorporation of HLA Cw4 molecules. This effect is associated with changes in viral envelope proteins conformation including an enhanced expression of the V3 loop of gp120, and of epitopes that are exposed upon CD4 binding. The gp120 conformational changes are consistent with the formation of a multimolecular complex between HLA class I and gp120/160. HLA Cw4 incorporation is also associated to a lower susceptibility to antibody neutralization. These findings have important implications for understanding the immune response to cryptic and conformational epitopes of the viral envelope.

Cell Line↗
PubMed1999

Recruiting comparative crosslinguistic evidence to address competing accounts of agrammatic aphasia.

Several hypotheses have been advanced whose aim has been to provide a descriptive generalization of comprehension patterns in agrammatic aphasia in terms of current linguistic theory, most notably, the Trace-Deletion Hypothesis. The basic insight of these syntactic accounts of aphasia is that chains are disrupted. In this paper, we seek to confront the Trace-Deletion Hypothesis (TDH) and one of its variants, the Double-Dependency Hypothesis (DDH), with discriminating, crosslinguistic data. We adduce evidence that on raising constructions both hypotheses are able to derive Spanish agrammatic data correctly. However, neither the TDH nor the DDH are able to account for above-chance performance on SV or VS truncated passives. Finally, only the DDH explains the observed data on passive constructions in which a postverbal subject follows the by phrase (V-by phrase-S). The VS word order data are the critical cases because focusing simply on English would not allow these structures to be tested and, in the case of the V-by phrase-S passive, both hypotheses make different predictions. While the data on raising constructions extend the range of both the TDH and the DDH, the VS data suggest that modifications are required.

Aphasia, Broca↗
PubMed1998

HIV-1-resistance phenotype conferred by combination of two separate inherited mutations of CCR5 gene.

BACKGROUND: Despite multiple exposures to HIV-1, some individuals remain uninfected, and their peripheral-blood mononuclear cells (PBMC) are resistant to in-vitro infection by primary HIV-1 isolates. Such resistance has been associated with a homozygous 32-base-pair deletion (delta 32) in the C-C chemokine receptor gene CCR5. We examined other mutations of the CCR5 gene that could be associated with resistance to HIV-1 infection. METHODS: We assessed the susceptibility of PBMC to in-vitro infection by HIV-1 isolates that use the CCR5 as the major coreceptor for viral entry in 18 men who had frequent unprotected sexual intercourse with a seropositive partner. We also did genotypic analysis of CCR5 alleles. One of the 18 exposed but uninfected men (who we refer to as ExU2) showed total resistance to in-vitro infection by CCR5-dependent viruses, and was found to carry a CCR5 delta 32 allele and a single point mutation (T-->A) at position 303 on the other allele. To find out whether the CCR5 mutation was restricted to ExU2's family or existed in the general population, we did genetic analyses of the CCR5 genotype in ExU2's father and sister and also in 209 healthy blood donors who were not exposed to HIV-1. FINDINGS: The m303 mutation found in ExU2 introduced a premature stop codon and prevented the expression of a functional coreceptor. The family studies revealed that the m303 mutant allele was inherited as a single mendelian trait. Genotype analysis showed that three of the 209 healthy blood donors were heterozygous for the mutant allele. INTERPRETATION: We characterise a new CCR5 gene mutation, present in the general population, that prevents expression of functional coreceptors from the abnormal allele and confers resistance to HIV-1 infection when associated to the delta 32 CCR5 mutant gene.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Double-agents and trace-deletion in agrammatism.

The Trace-Deletion Hypothesis (henceforth TDH; Grodzinsky 1986, 1995) states that syntactic traces are deleted in agrammatism and that whenever a trace is deleted, a default strategy is activated. The default strategy assigns the role of Agent to the first NP. In structures where a second NP receives the Agent role syntactically, the consequence is that the agrammatic representation contains two conflicting Agents for the same action. This is the mechanism that induces guessing and the random performance on comprehension tests that has often been observed for passives and certain other structures. In this paper, we isolate the default strategy of the TDH, using a sentence-picture matching task in which one of the pictures matches the meaning arrived at by the default strategy. Our results show that an agrammatic representation does not involve double-Agents, and thus the default strategy (and therefore the TDH) is refuted.

Adolescent↗
PubMed1998

Pathogenetic and clinical aspects of C1 inhibitor deficiency.

People deficient in C1-INH present recurrent angioedema localized to subcutaneous or mucous tissues. The defect can be caused by impaired synthesis, due to a genetic defect (hereditary angioedema), or by increased catabolism (acquired angioedema). In our experience the majority of patients with acquired angioedema (16 of 18) have autoantibodies to C1-INH in their serum. These autoantibodies bind to C1-INH with different and generally low affinity. The vasopermeability mediator responsible for attacks is still undefined: bradykinin (derived from cleavage of high molecular weight kininogen) and a kinin-like peptide (derived from the second component of complement) still remain the two primary candidates. We examined the systems controlled by C1-INH (complement, contact system, fibrinolysis and coagulation) and found that all of them are activated during angioedema attacks. Activation of the coagulation leads to generation of thrombin whose vasoactive effect can thus influence edema formation. Treatment of severe angioedema attacks is satisfactorily performed with C1-INH plasma concentrate although patients with an acquired defect frequently need very high doses. Attenuated androgens effectively prevent attacks in hereditary angioedema, but their safety, on the very long-term, needs to be further assessed. Acquired angioedema generally fail to respond to these drugs, but can be treated prophylactically with antifibrinolytic agents.

Abdomen, Acute↗