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A Cattaneo

Publications and source records attributed to A Cattaneo.

At least 73 records · Page 4Linked to original sources
PubMed1998

Assembled IgG molecules are exported from the endoplasmic reticulum in myeloma cells despite the retention signal SEKDEL.

The KDEL retention signal, when added at the C-terminal of the constant region of light and heavy chains of immunoglobulins is able to efficiently retain assembled immunoglobulins only in cells of nonlymphoid origin. In transfected myeloma cells the wild type and the KDEL-Ig mutants are secreted with the same efficiency. This phenomenon is not due to a proteolytic cleavage of the KDEL signal nor to a lack of intermolecular disulfide bond formation and is not due to an impaired recognition of the KDEL signal in myeloma cells. Thus, the constitutive secretion of assembled immunoglobulins, currently considered to follow a default process, appears to be regulated by a mechanism that is able to overcome an efficient ER retention system.

Amino Acid Sequence↗
PubMed1998

Periphyton as an indicator of water quality in the St Lawrence River (Québec, Canada).

The performance of various algal indices to document improvements in water quality across a low nutrient concentration gradient was assessed during 2 years in the St Lawrence River (Quebec, Canada). Water-quality variables and periphyton samples were collected on navigational buoys near Montreal during the spring, summer and fall of 1994 and 1995. Exposure to urban wastewater varied widely within the sector surrounding the island of Montreal, with some areas upstream receiving no direct effluents and areas further downstream receiving treated and untreated wastewater. Faecal coliform concentrations provided a good tracer of effluents and were significantly correlated to nutrient concentrations (r = 0.33-0.72, p < 0.001) and water transparency (r = 0.70, p < 0.001). Despite a strong gradient in faecal coliform concentration (< 2 to > 20 000 UFC/100 ml), algal biomass and diversity did not reflect differences between sites with varying levels of urban wastewater. Taxonomic composition of periphyton communities, particularly the presence of the cyanophyte Plectonema notatum Schmidle, was related (r = 0.48, p = 0.004) to exposure to urban effluents. Variables describing seasonal changes (temperature, Julian day, river discharge, conductivity, NO2-NO3) explained a large fraction of total variance (38-52% of total variance) and thus exerted the predominant influence on algal biomass and species composition in the St Lawrence River. Variables describing the presence of effluents explained 1-22% of the variance in compositional data. Subtle changes in periphyton species composition were the only response to different levels of exposure to urban wastewater in the Montreal area, which represented relatively small differences in comparison to natural seasonal variability.

Journal Article↗
PubMed1998

The effects of anti-nerve growth factor monoclonal antibodies on developing basal forebrain neurons are transient and reversible.

In order to reassess the role of nerve growth factor (NGF) on rat basal forebrain cholinergic neurons (BFCNs) survival and/or phenotype maturation during the early postnatal life, we immunoneutralized NGF in vivo. Hybridoma cells producing the neutralizing anti-NGF monoclonal antibody alphaD11 were implanted in the lateral ventricle of the rat at different postnatal ages (P2, P8 and P15) and the effects on the number and the soma size of cholinacetyltransferase (ChAT) positive neurons were analysed 1, 2 or 3 weeks after the injection. A marked decrease in the number and in the soma size of BFCNs was observed implanting hybridoma cells at P2 and performing the analysis 1 week later. These effects are reversed 3 weeks after the implant of hybridoma cells at P2. At this time point, the levels of alphaD11 antibodies in the brain parenchyma are still in a vast molar excess over endogenous NGF. No effects on BFCNs were observed implanting alphaD11 cells at P15 while LGN neurons showed marked shrinkage. Our results demonstrate that the reduction in the number of ChAT-positive neurons during the first two postnatal weeks of anti-NGF treatment is not due to cell death. We conclude that NGF is not a survival factor for BFCNs, and that the influence of NGF on BFCNs cell maturation during the first 2 postnatal weeks is transient and reversible. Our results on tyrosine kinase (Trk) coexpression, suggest that NGF may cooperate with other factors in the cholinergic phenotype differentiation and maintenance after the second postnatal week.

Age Factors↗
PubMed1998

Recommendations for the implementation of Kangaroo Mother Care for low birthweight infants. International Network on Kangaroo Mother Care.

Good quality care of low birthweight infants could reduce neonatal mortality in low-income countries, but the technologies used in rich countries are inappropriate. Kangaroo Mother Care does not need expensive and sophisticated equipment, and for its simplicity it can be applied almost everywhere, including peripheral maternity units of very low-income countries. Kangaroo Mother Care (KMC) can also contribute to the humanization of neonatal care and to better bonding between mother and baby in both poor and rich countries. A group of health professionals with experience in KMC met in a workshop to discuss its effectiveness, safety, applicability and acceptability in different settings: from first and second level maternity units in settings with very limited resources, to second and third level units in settings with limited resources, to second and third level maternity and neonatal care units in settings with ample resources and infant mortality rates <15/1000. The paper summarizes the recommendations of this group of health professionals for the implementation of KMC in these various settings, together with suggested research priorities.

Developing Countries↗
PubMed1998

Kangaroo mother care for low birthweight infants: a randomized controlled trial in different settings.

A randomized controlled trial was carried out for 1 y in three tertiary and teaching hospitals, in Addis Ababa (Ethiopia), Yogyakarta (Indonesia) and Merida (Mexico), to study the effectiveness, feasibility, acceptability and cost of kangaroo mother care (KMC) when compared to conventional methods of care (CMC). About 29% of 649 low birthweight infants (LBWI; 1000-1999 g) died before eligibility. Of the survivors, 38% were excluded for various reasons, 149 were randomly assigned to KMC (almost exclusive skin-to-skin care after stabilization), and 136 to CMC (warm room or incubator care). There were three deaths in each group and no difference in the incidence of severe disease. Hypothermia was significantly less common in KMC infants in Merida (13.5 vs 31.5 episodes/100 infants/d) and overall (10.8 vs 14.6). Exclusive breastfeeding at discharge was more common in KMC infants in Merida (80% vs 16%) and overall (88% vs 70%). KMC infants had a higher mean daily weight gain (21.3 g vs 17.7 g) and were discharged earlier (13.4 vs 16.3 d after enrolment). KMC was considered feasible and presented advantages over CMC in terms of maintenance of equipment. Mothers expressed a clear preference for KMC and health workers found it safe and convenient. KMC was cheaper than CMC in terms of salaries (US$ 11,788 vs US$ 29,888) and other running costs (US$ 7501 vs US$ 9876). This study confirms that hospital KMC for stabilized LBWI 1000-1999 g is at least as effective and safe as CMC, and shows that it is feasible in different settings, acceptable to mothers of different cultures, and less expensive. Where exclusive breastfeeding is uncommon among LBWI, KMC may bring about an increase in its prevalence and duration, with consequent benefits for health and growth. For hospitals in low-income countries KMC may represent an appropriate use of scarce resources.

Breast Feeding↗
PubMed1998

Pediatric risk of mortality: an assessment of its performance in a sample of 26 Italian intensive care units.

OBJECTIVE: To assess the validity of the Pediatric Risk of Mortality (PRISM) scoring system in accurately predicting the probability of mortality in an Italian intensive care unit (ICU) sample. DESIGN: Prospective, observational, multicenter study. SETTING: Twenty-six Italian ICUs classified into two groups: a) ICUs specifically dedicated to treating pediatric patients; and b) adult ICUs treating children on a regular basis. PATIENTS: Consecutive patients (n = 1,533) <15 yrs of age admitted during 1 yr. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: To assess the performance of the PRISM scoring system, the discrimination and calibration measures were adopted both in the whole population and in 12 preselected subgroups. A good discrimination capability of the scoring system was observed for both the whole population and subgroups (areas under the receiver operating characteristic curves were never <0.82). On the other hand, we documented an unsatisfactory calibration capability in the whole population and in most subgroups (p values of the Hosmer-Lemeshow goodness-of-fit test were <.001 in all but two subgroups). CONCLUSIONS: The analyses suggest that the unsatisfactory calibration of PRISM can be attributed to various reasons. Among those reasons, a poor performance of the system, as well as its sensitivity to factors not connected to clinical ICU performance, seem particularly important. A special caution is needed in adopting a severity of illness scoring system to assess quality of care, particularly in contexts different from the one in which the instrument was originally developed.

Adolescent↗
PubMed1998

Predicting outcome in the intensive care unit using scoring systems: is new better? A comparison of SAPS and SAPS II in a cohort of 1,393 patients. GiViTi Investigators (Gruppo Italiano per la Valutazione degli interventi in Terapia Intensiva). Simplified Acute Physiology Score.

OBJECTIVES: This study sought to compare the performance of the old and new versions of the Simplified Acute Physiology Score, SAPS and SAPS II, in classifying patients according to the risk of hospital mortality. METHODS: To compare the performance of the two systems, measures of association between the scores and observed mortality were adopted, together with discrimination (area under the Receiver Operating Characteristics curve) and calibration (goodness-of-fit statistics) estimates. Subjects were 1,393 eligible patients recruited during 1 month in 1994. The outcome measure was vital status at hospital discharge. RESULTS: SAPS II was associated more strongly with hospital mortality than the earlier version. SAPS II also had better discrimination ability than SAPS (area under Receiver Operating Characteristics curve 0.80 versus 0.74) and predicted an overall number of deaths (416.5) closer to the observed figure (475) than SAPS (267.7). Conversely, neither SAPS nor SAPS II fitted our data. Both P values derived from goodness-of-fit statistics were lower than 0.05. CONCLUSIONS: SAPS II offers a real improvement compared with SAPS in its ability to explain hospital mortality, but its standard parameters do not fit our data from Italy. The role and impact of potential determinants of this lack of fit, such as random errors and confounders related to casemix and/or quality of care should be clarified before this scoring system be used outside formal research projects. Special caution is suggested when SAPS II is adopted to predict mortality to compare intensive care unit performance across different countries and systems of care.

Adult↗
PubMed1997

Activity-dependent dendritic targeting of BDNF and TrkB mRNAs in hippocampal neurons.

The mechanisms underlying the subcellular localization of neurotrophins and their receptors are poorly understood. We show that in cultured hippocampal neurons, the mRNAs for BDNF and TrkB have a somatodendritic localization, and we quantify the extent of their dendritic mRNA localization. In the dendrites the labeling covers on average the proximal 30% of the total dendritic length. On high potassium depolarization, the labeling of BDNF and TrkB mRNA extends on average to 68% of the dendritic length. This increase does not depend on new RNA synthesis, is inhibited by the Na+ channel blocker tetrodotoxin, and involves the activation of glutamate receptors. Extracellular Ca2+, partly flowing through L-type Ca2+ channels, is absolutely required for this process to occur. At the protein level, a brief stimulation of hippocampal neurons with 10 mM KCl leads to a marked increase of BDNF and TrkB immunofluorescence density in the distal portion of dendrites, which also occurs, even if at lower levels, when transport is inhibited by nocodazole. The protein synthesis inhibitor cycloheximide abolishes this increase. The activity-dependent modulation of mRNA targeting and protein accumulation in the dendrites may provide a mechanism for achieving a selective local regulation of the activity of neurotrophins and their receptors, close to their sites of action.

Action Potentials↗
PubMed1997

Co-localization of truncated tau and DNA fragmentation in Alzheimer's disease neurones.

Monoclonal antibody MN423 stains all hallmarks of tau neurofibrillary pathology in Alzheimer's disease (AD), without reacting with full-length tau. It recognizes tau molecules which are cleaved at Glu-391, suggesting that tau is endogenously truncated in AD brains. We investigated whether truncation of tau takes place in pre-tangle neurones. Our results showed that tau truncation occurs inside AD neurones in the absence of other signs of AD neurofibrillary pathology. Using in situ end labelling (ISEL) of DNA we found evidence for DNA fragmentation in a significant subpopulation of MN423-positive neurones. Our results therefore suggest that tau truncation is an early intracellular event preceding cell death in AD.

Aged↗
PubMed1997

Oxidative metabolism in cultured fibroblasts derived from sporadic Alzheimer's disease (AD) patients.

Fibroblasts from Alzheimer's disease (AD) patients displayed decreased cytochrome c oxidase (complex IV) activity (P < 0.05). The basal oxygen consumption rate (QO2) and the response to an uncoupler of oxidative phosphorylation did not differ between AD and control fibroblasts. The QO2 of AD fibroblasts was more susceptible (P < 0.05) to inhibition by azide in the range 0.5-5 mM. The basal intracellular pH (pHi) in AD fibroblasts was significantly more acidic than in control ones. The results support the hypothesis that subtle dysfunctions of oxidative energy-producing processes are present in fibroblasts from sporadic AD patients. The alterations observed scantly influence the fibroblasts functioning even in stressful conditions; however in tissues, such as the brain, that rely heavily on oxidative metabolism for their function, similar alterations may trigger molecular mechanisms leading to cell damage.

Aged↗
PubMed1997

Rescue of a neutralizing anti-viral antibody fragment from an intracellular polyclonal repertoire expressed in mammalian cells.

The intracellular expression of recombinant antibodies in mammalian cells is an experimental strategy to inhibit in vivo the function of selected molecules. However, one limitation of this technology is represented by the unpredictable behaviour of antibodies, under conditions of intracellular expression. For this reason, it would be desirable to exploit intracellular expression of antibodies to select or rescue more efficient ones from a polyclonal mixture. In this work we have successfully explored this possibility by rescuing a neutralizing anti-viral antibody fragment from an intracellularly expressed anti-reverse transcriptase polyclonal repertoire.

3T3 Cells↗
PubMed1997

NGF antibodies impair long-term depression at the mossy fibre-CA3 synapse in the developing hippocampus.

Nerve growth factor (NGF) and other neurotrophins are proteins involved in neuronal survival and differentiation. Much experimental evidence is now drawing attention into a role of neurotrophins in activity-dependent synaptic plasticity processes. We now show that slices from rats chronically deprived of NGF, by intraventricular injection of alpha D11 hybridoma cells, which produce monoclonal antibodies against NGF, display a reduced probability of induction of long-term depression at the mossy fibre-CA3 synapse.

Animals↗
PubMed1997

Targeting vectors for intracellular immunisation.

We define intracellular immunization as the inhibition or inactivation of the function of a molecule by the ectopic intracellular expression of antibody binding domains which recognise the molecule. Such recombinant antibodies can be directed to different compartments of eukaryotic cells by means of previously defined targeting signals, thus permiting the study of any molecule in any cellular compartment for which an antibody is available. For this purpose, we have created a set of vectors based on the VHExpress vector described [Persic, L., Roberts, A., Wilton, J., Cattaneo, A., Bradbury, A. and Hoogenboom, H.R. (1997) An integrated vector system for the eukaryotic expression of antibodies or their fragments after selection from phage display libraries. Gene 187, 000-000], which has been modified to express scFvs (single chain fragments) linked to specific targeting signals. These permit the localisation of scFvs to different intracellular compartments: the endoplasmic reticulum (scFvE-er), the nucleus (scFvE-nuclear), the mitochondria (scFvE-mit), the cytoplasm (scFvE-cyto), and as secreted proteins (scFvE-sec). The function of these vectors has been assessed by the immunofluorescence of COS cells transiently transfected with constructs containing the alphaD11 scFv.

Amino Acid Sequence↗
PubMed1997

An integrated vector system for the eukaryotic expression of antibodies or their fragments after selection from phage display libraries.

Phage display is now an established method to select antibody fragments specific for a wide range of diverse antigens. In particular, isolation of human monoclonal antibodies has become a reality and for most purposes bacterial expression of the selected recombinant antibody fragments is sufficient. However, there are some cases where the expression of complete human immunoglobulin in mammalian cells is, if not essential, at least desirable. For this reason we have designed and constructed a set of mammalian expression vectors which permit facile and rapid cloning of antibody genes for both transient and stable expression in mammalian cells. Immunoglobulin genes may be cloned into these expression vectors as V regions or as Fabs for expression as either complete antibodies or as Fab fragments, using restriction sites which are rare in human V genes. All the important elements in the vectors--promoter, leader sequence, constant domains and selectable markers--are flanked by unique restriction sites, allowing simple substitution of elements. The vectors have been evaluated using the variable regions from the neutralizing anti-nerve growth factor (NGF) antibody, alphaD11, and the V regions from 2E10, a scFv selected from a scFv phagemid library.

Animals↗
PubMed1997

Neurotrophin-3 promotes the survival of oligodendrocyte precursors in embryonic hippocampal cultures under chemically defined conditions.

embryonic rat hippocampal cells were cultured in basal medium with or without addition of the neurotrophin NT-3. After culturing in these extreme conditions, the effects of NT-3 on the neuronal and on the glial components were assessed. Neurons survived even in the absence of NT-3 but failed to reach terminal differentiation. On the other hand, NT-3 promoted the survival but not the proliferation and/or the differentiation of oligodendrocytes precursors present in the same culture, an effect that was reversed by the addition of neutralizing antibodies against NT-3. Type I or II astrocytes were not affected by NT-3. These results reinforce the role for NT-3 in oligodendrocyte lineage development and allow to dissect the roles of this neurotrophin in survival and in proliferation/differentiation of oligodendrocytes.

Animals↗