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Biomedical subjects

E Serra

Publications and source records attributed to E Serra.

At least 19 recordsLinked to original sources
PubMed2006

Cerebral blood flow in fulminant hepatitis.

Fulminant hepatic failure (FHF) is often complicated with cerebral edema, intracranial hypertension, and coma. Cytotoxic and vasogenic factors have been recognized in the etiology of cerebral edema. One of the main causes seems to be the accumulation of glutamine in astrocytes, which is produced from ammonia and the excitatory neurotransmitter glutamate. Ammonia is detoxified within the brain in astrocytes, where it increases the osmotic pressure for water. Ammonia-induced astrocytic water accumulation seems to act as an integrative trigger for the development of intracranial hypertension. While cerebral blood flow is sometimes reduced in the first stage of FHF, as compensatory cerebral vasoconstriction to reduce mean arterial pressure, it later increases as hyperammonemia decreases cerebral arteriolar tone. Despite vasodilation in the systemic and splanchnic beds at early stages of the disease, cerebral vessel resistance may increase, so that cerebral perfusion pressure may be preserved. When cerebral vascular tone is no longer effective in the course of illness, vasodilation gradually develops and rapidly becomes poorly responsive to carbon dioxide stimulation, which signifies loss of autoregulatory tone and cerebral hyperemia develops. Prolonged excessive flow may lead to brain swelling, vasogenic edema, and intracerebral hemorrhage. Brain edema further aggravates the critically reduced cerebral perfusion and is responsible for the high mortality.

Blood Flow Velocity↗
PubMed2006

cAMP phosphodiesterase activity evaluation in human carcinoma of salivary glands.

The aim of this study was to evaluate differences of cAMP-PDE activity in human salivary glands, between a control group and some different benign tumours groups and, where present, with 2 malignant tumors groups. The value of the enzymatic activity in the groups analysed was 50% lower than control samples. The differences between the control group (82 +/- 7.9 nmols/mg of protein) and the 3 pathologic groups (Benign A: 44 +/- 6.2; Malignant A: 40 +/- 16; Benign B: 40 +/- 14.2; Malign A: 9.1; Benign C: 22 nmols/mg of protein) are statistically significant.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2005

Deficient control of Trypanosoma cruzi infection in C57BL/6 mice is related to a delayed specific IgG response and increased macrophage production of pro-inflammatory cytokines.

Earlier work in Trypanosoma cruzi-infected C57BL/6 and BALB/c mice revealed an acute disease, of lethal outcome in the former group and lesser severity in BALB/c mice. Fatal course was not accompanied by an increased parasite load, but by a substantial imbalance between pro- and anti-inflammatory cytokine serum levels. To better characterise the mechanisms allowing the host to restrain the infection, we have now studied the specific IgG production and in vitro behaviour of peritoneal macrophages (PMs) when exposed to T. cruzi. BALC/c mice displayed higher serum levels of specific immunoglobulins in the first weeks of acute infection. In vitro infected PMs showed no between-group differences in the number of intracellular parasites, although TNFalpha levels were significantly higher in culture supernatants from C57BL/6 mice. Because an LPS-based pretreatment (desensitisation protocol followed by a sublethal LPS dose) reduced disease severity of C57BL/6 mice, we next explored the features of the in vitro infection in PMs from mice subjected to such protocol. PMs from LPS-pretreated mice had a decreased production of TNFalpha and IL-1beta, becoming more permissive to parasite replication. It is concluded that deficient control of T. cruzi infection in C57BL/6 mice may also involve a less satisfactory specific IgG response and increased TNFalpha production by PMs. Improved disease outcome in LPS-pretreated mice may be associated with the reduced inflammatory cytokine production by PMs, but the impaired ability of these cells to control parasite growth suggests that compensatory mechanisms are operating in the in vivo situation.

Animals↗
PubMed2004

Cyclase and phosphodiesterase activity on pre-T lymphoid human cells, treated with dimethyl sulfoxide (DMSO).

Our aim is to estimate the role of the DMSO on pre-T lymphoid human cells, we have searched the cyclase and phosphodiesterase activity. We have studied the GTPspecific cyclase (G-Case) and have observed an analogous course to that one of the cAMP-PDE, where, in both cases, the differences ratio is approximately 5. For the cyclase activity values it has been found that cAMP neo formed is undeterminable in these cells, for the controls and the treated samples.

1-Methyl-3-isobutylxanthine↗
PubMed2002

Volumetric determination of the wear of ceramics for hip joints.

Osteolysis relating to the reaction cascade to wear debris is the main cause of the failure of arthroprostheses. New materials are still under development to minimise the wear of joints and to improve in this way the performance of total joint replacements. Testing the wear performance of very low wear materials is a rather sophisticated technique. Currently, the worn volume is calculated from the weight variations of the sample, observed from wear testing. This method may be limited especially when very low weight differences are to be evaluated on high hardness, high-density materials like CoCr alloys or ceramics like alumina or zirconia. In the present work, the tribological behaviour of ceramic biomaterials like alumina, Y-TZP and alumina-zirconia composites was evaluated by a pin-on-disc apparatus under different testing conditions. The worn volume was calculated by the use of 3-D (three-dimensional) optical profilometry data. Comparison between 3-D optical profilometry and gravimetric wear data shows the better accuracy of the profilometric method in the determination of wear rate in the range of 10(-7) mm3 (mN(-1)) or lower.

Biomechanical Phenomena↗
PubMed2002

Differential susceptibility to acute Trypanosoma cruzi infection in BALB/c and C57BL/6 mice is not associated with a distinct parasite load but cytokine abnormalities.

Inoculation of Trypanosoma cruzi, Tulahuén strain, into C57BL/6 and BALB/c mice led to an acute infection characterized by marked parasitaemia, myocardial inflammation and thymocyte depletion. While C57BL/6 mice showed a progressive and lethal disease, BALB/c mice partly recovered. To characterize these murine models more effectively, we studied the parasite burden, serum levels of major infection outcome-related cytokines, the in vitro features of T. cruzi infection in peritoneal macrophages and the immunophenotype of thymic cells. The greater disease severity of T. cruzi-infected C57BL/6 mice was not linked to an increased parasite load, as parasitaemia, myocardial parasite nests and amastigote counts in peritoneal macrophages were not different from those in BALB/c mice. Cortical thymocyte loss was accompanied by the presence of apoptotic bodies and fragmented nuclear DNA, whereas fluorocytometric analysis at 17 days postinfection (p.i.) revealed a more pronounced loss of CD4+ CD8+ cells in C57BL/6 mice. This group displayed higher levels of TNF-alpha on days 14 and 21 p.i., in the presence of lower IL-1beta and IL-10 concentrations by days 14 and 21, and days 7 and 14 p.i., respectively. Day-21 evaluation showed higher concentrations of nitrate and TNF-alpha soluble receptors in C57BL/6 mice with no differences in IFN-gamma levels, with respect to the BALB/c group. Increased morbidity of C57BL/6 T. cruzi-infected mice does not seem to result from an aggravated infection but from an unbalanced relationship between pro- and anti-inflammatory mediators.

Acute Disease↗
PubMed2001

Trypanocidal drug benznidazole impairs lipopolysaccharide induction of macrophage nitric oxide synthase gene transcription through inhibition of NF-kappaB activation.

In murine macrophages, inducible NO synthase II (NOSII) gene expression is promoted at a transcriptional level by LPS and/or IFN-gamma with benznidazole (BZL), a trypanocidal drug, acting to down-regulate NOSII gene induction and hence inhibiting NO production. By performing transient transfection experiments, we now report that BZL also inhibited the expression of NOSII gene promoter or multimerized NF-kappaB binding site controlled reporter genes. By contrast, no effect was observed on the expression of a reporter gene under the control of the NOSII promoter-derived IFN regulatory factor element. EMSAs demonstrated that BZL inhibited the nuclear availability of NF-kappaB in stimulated macrophages. NF-kappaB is activated in macrophages by phosphorylation, ubiquitination, and subsequent proteolysis of IkappaB. Within this setting, Western blot was also performed to show that BZL blocked IkappaBalpha degradation. Collectively, these results demonstrate that BZL is able to specifically inhibit macrophage NF-kappaB activation after LPS plus IFN-gamma stimulation.

Animals↗
PubMed2001

Somatic NF1 mutational spectrum in benign neurofibromas: mRNA splice defects are common among point mutations.

Neurofibromas, benign tumors that originate from the peripheral nerve sheath, are a hallmark of neurofibromatosis type 1 (NF1). Although loss of heterozygosity (LOH) is a common phenomenon in this neoplasia, it only accounts for part of the somatic NF1 mutations found. Somatic point mutations or the presence of "two hits" in the NF1 gene have only been reported for a few neurofibromas. The large size of the NF1 gene together with the multicellular composition of these tumors has greatly hampered their molecular characterization. Here, we present the somatic NF1 mutational analysis of the whole set of neurofibromas studied by our group and consisting in 126 tumors derived from 32 NF1 patients. We report the identification of 45 independent somatic NF1 mutations, 20 of which are reported for the first time. Different types of point mutations together with LOH affecting the NF1 gene and its surrounding region or extending along the 17q arm have been found. Among point mutations, those affecting the correct splicing of the NF1 gene are common, coinciding with results reported on germline NF1 mutations. In most cases, we have been able to confirm that both copies of the NF1 gene are inactivated. We have also found that both somatic and germline mutations can be expressed at the RNA level in the neoplastic cells. Furthermore, we have observed that the study of more than one tumor derived from the same patient is useful for the identification of the germline mutation. Finally, we have noticed that the culture of neurofibromas and their fibroblast clearance facilitates LOH detection in cases in which it is difficult to determine.

Alleles↗
PubMed2001

Potential mechanism of fibronectin deposits in acute renal failure induced by mercuric chloride.

Many glomerular diseases are associated with changes in the expression and distribution in the components of extracellular matrix. A remarkable feature in acute renal failure induced by mercuric chloride in rats was large fibronectin (Fn) deposits in kidneys 1 h post-HgCl2 injection (5 mg/kg body wt., s.c.). Our study examined some mechanisms as potential explanation of the early Fn deposits in mercuric chloride induced acute renal failure. Total tissue mRNA of livers and kidneys of control and treated rats were used in Northern blot to determine whether accumulation of Fn in kidney is associated with increases in the expression of this protein in the kidney and/or in the liver. Analysis of Fn levels by Western blot were also performed. Northern blot did not show significant difference between control and treated rats, while the abundance of polymerized-Fn in kidney tissue was increased 1 h and 5 h post HgCl2 injection. HgCl2 influence on Fn folding was studied in vitro to detect possible conformational changes that could altered its normal pattern of matrix assembly and/or binding to different ligands. In this context HgCl2 binding to Fn was measured following native tryptophan fluorescence of Fn in the presence of HgCl2 (0.5-250 mM). Binding parameters for the HgCl2-Fn complex formation were Kd = (1.6 +/- 0.2) 10(-4) M; n = 1 +/- 0.3, indicating a low apparent affinity and one type binding site. Thermal denaturation of Fn showed, between 30-60 degrees C, a soft reversible conformational change, while between 75-80 degrees C a highly and irreversible transition is produced suggesting a modification of the tertiary structure. HgCl2 abolished this transition. The kinetic of thermal unfolding of Fn was also measured and the effects observed due to HgCl2 presence reinforced the previous data. Finally, the effect of HgCl2 on Fn binding to denatured collagen (gelatin) was also measured as an index of the effect of this cation on biological properties of Fn. Fn binds gelatin strongest in the presence of HgCl2. Our results suggest that higher Fn deposits in kidney-treated rats seems not to be associated to augmented mRNA-Fn neither in kidney nor in liver. On the other hand, increased levels of polymerized Fn abundance was observed in kidney tissue from mercury-treated rats. We also describe that HgCl2 promotes, in vitro, conformational changes on Fn structure, inducing its denaturation and increasing its binding to gelatin, all events that could be related to the Fn deposits in renal tissues of HgCl2 treated rats, and could be expected in other situations that promoted interstitial fibrosis, not associated to overexpression of matrix-proteins.

Acute Kidney Injury↗
PubMed2001

Mitotic recombination effects homozygosity for NF1 germline mutations in neurofibromas.

Pure populations of neurofibroma-derived Schwann cells bearing both NF1 mutated alleles (NF1-/-) have been isolated from different neurofibromas showing loss of heterozygosity of nearly the entire 17q chromosome. By comparing molecular and fluorescent in situ hybridization analysis of these cells, we demonstrate mitotic recombination is the mechanism underlying this type of loss of heterozygosity leading to reduction to homozygosity of NF1 germline mutation.

Chromosomes, Human, Pair 17↗
PubMed2001

Oral manifestations of HIV positive children.

Oral manifestations in HIV positive children were observed in thirty-eight HIV infected children that have received care at the Special Care Dentistry Center (SCDC) of the School of Dentistry, University of Sao Paulo. Results have shown that 52.63% of the children presented at least one oral manifestation related with HIV/AIDS. Angular cheilitis occurred in 28.94%, parotid gland bilateral enlargement, pseudomembranous candidiasis and erythematous candidiasis in 18.42%, conventional gingivitis in 13.15%, herpes simplex in 5.26%, hairy leukoplakia, recurrent aphthous ulcer and condyloma acuminatum in 2.63%. Although enamel hypoplasia occurred in 23.68%, this could not be attributed specifically to HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Schwann cells harbor the somatic NF1 mutation in neurofibromas: evidence of two different Schwann cell subpopulations.

Neurofibromas are one of the most characteristic features of neurofibromatosis type 1 (NF1), an inherited autosomal-dominant neurogenetic disorder affecting 1 in 3500 individuals worldwide. These benign tumors mainly consist of Schwann cells (SCs) and fibroblasts. Recent evidence demonstrates that somatic mutations at the NF1 gene are found in neurofibromas, but it has not been demonstrated whether SCs, fibroblasts and/or both cell types bear a somatic loss of NF1. We recently established a cell culture system that allows selective expansion of human SCs from neurofibromas. We cultured pure populations of SCs and fibroblasts derived from 10 neurofibromas with characterized NF1 mutations and found that SCs but not fibroblasts harbored a somatic mutation at the NF1 locus in all studied tumors. Furthermore, by culturing neurofibroma-derived SCs under different in vitro conditions we were able to obtain two genetically distinct SC subpopulations: NF1(-/-) and NF1(+/-). These data strongly support the idea that NF1 mutations in SCs, but not in fibroblasts, correlate to neurofibroma formation and demonstrate that only a portion of SCs in neurofibromas have mutations in both NF1 alleles.

Cell Division↗
PubMed2000

Cold shock induces the insertion of a cryptic exon in the neurofibromatosis type 1 (NF1) mRNA.

Alternative splicing is a regulatory process of gene expression based on the flexibility in the selection of splice sites. In this manuscript we present the characterisation of an alternative splicing of the NF1 pre-mRNA induced by cold-shock conditions. We demonstrate that the accuracy of the splicing mechanism was perturbed after keeping samples for a short period of time at room temperature, resulting in the insertion of a 31-bp cryptic exon between exons 4a and 4b of the NF1 mRNA. This alternative splicing is not cell type specific and is not induced by other stress conditions such as heat shock or hyper-osmolarity. The alternative spliced mRNA is efficiently transported to the cytoplasm and it is proven to belong to the poly A(+)mRNA fraction. Previous misleading interpretations about this transcript, together with our finding relating its presence to cold shock and not to the NF1 disease, strongly indicate that this phenomenon should be taken into account in genetic testing when RNA methodology is used for mutation detection. This is the first description of an alternative splicing induced by cold shock in a human pre-mRNA and should provide further insights into the factors that control alternative splicing.

Alternative Splicing↗
PubMed2000

Mutations affecting mRNA splicing are the most common molecular defects in patients with neurofibromatosis type 1.

Neurofibromatosis type 1 (NF1) is one of the most common inherited disorders in humans and is caused by mutations in the NF1 gene. To date, the majority of the reported NF1 mutations are predicted to result in protein truncation, but very few studies have correlated the causative NF1 mutation with its effect at the mRNA level. We have applied a whole NF1 cDNA screening methodology to the study of 80 unrelated NF1 patients and have identified 44 different mutations, 32 being novel, in 52 of these patients. Mutations were detected in 87% of the familial cases, but in 51% of the sporadic ones. At least 15 of the 80 NF1 patients (19%) had recurrent mutations. The study shows that in 50% of the patients in whom the mutations were identified, these resulted in splicing alterations. Most of the splicing mutations did not involve the conserved AG/GT dinucleotides of the splice sites. One frameshift, two nonsense and two missense mutations were also responsible for alterations in mRNA splicing. The location and type of mutation within the NF1 gene, and its putative effect at the protein level, do not indicate any relationship to any specific clinical feature of NF1. The high proportion of aberrant spliced transcripts detected in NF1 patients stresses the importance of studying mutations at both the genomic and RNA level. It is possible that part of the clinical variability in NF1 could be due to mutations affecting mRNA splicing, which is the most common molecular defect in NF1.

Adult↗
PubMed2000

Non-invasive ventilatory approach to treatment of acute respiratory failure in neuromuscular disorders. A comparison with endotracheal intubation.

OBJECTIVE: Prospectively to investigate the efficacy of non-invasive positive pressure ventilation (NPPV) combined with cricothyroid "mini-tracheostomy" (CM) as a first-line intervention in patients with acute respiratory failure (ARF) of neuromuscular origin, in comparison with positive pressure ventilation (PPV) via endotracheal intubation (ETI). DESIGN: Prospective analysis of the short-term outcomes of 14 non-consecutive patients suffering from ARF of neuromuscular origin who were administered NPPV and comparison with the outcomes of 14 matched historical control patients receiving conventional mechanical ventilation (MV) via ETI. SETTING: Adult five-bedded respiratory intensive care unit in a university hospital. PATIENTS AND INTERVENTIONS: Fourteen neuromyopathic patients who developed hypercapnic ARF and were submitted to NPPV (group A) and fourteen matched historical control patients, who were administered PPV via ETI (group B). Seven subjects receiving NPPV also underwent CM. OUTCOME MEASURES: Mortality during ICU stay and treatment failure were evaluated; treatment failure was defined as death or the need for ETI for the NPPV group and as death or the inability to wean from MV for the control group. Length of stay in the ICU and time to improvement, defined as the time required for a significant relief of dyspnea and neurologic impairment and for correction of arterial blood gases, were also compared. RESULTS: Intra-hospital mortality and treatment failure were lower in the NPPV group than in the conventional PPV via ETI group (2 vs 8 cases and 4 vs 11 cases, respectively). In addition, the duration of ICU stay for subjects who underwent NPPV was shorter than for patients who were intubated (13.6 +/- 9.7 vs 47.1 +/- 51.9 days). "Mini-tracheostomy" was well tolerated and no significant side effects were encountered. Two patient were excluded from the study because they showed a severe inability to swallow and needed to be intubated to protect the upper airway from the risk of aspiration. CONCLUSIONS: Non-invasive positive pressure ventilation in combination with CM may be considered as a safer and more effective alternative to ETI in the treatment of patients with neuromuscular disorders (NMD) who develop ARF and require MV; nevertheless, patient selection remains important, since a significant proportion of neuromyopathic patients might have to be excluded from NPPV because of severe risk of aspiration.

Acute Disease↗