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L Perin

Publications and source records attributed to L Perin.

18 recordsLinked to original sources
PubMed2006

Burkholderia silvatlantica sp. nov., a diazotrophic bacterium associated with sugar cane and maize.

In a previous study, nitrogen-fixing isolates were recovered from the rhizosphere of maize and from surface-sterilized leaves of sugar cane cultivated in Rio de Janeiro, Brazil. On the basis of 16S rRNA gene sequence similarities, these isolates were identified as belonging to the genus Burkholderia, and whole-cell-protein profiles demonstrated that they are closely related to each other. In the present study, novel isolates were recovered from the roots of different sugar-cane varieties cultivated in diverse geographical regions of Brazil. Twenty-one nitrogen-fixing isolates were analysed using polyphasic taxonomy criteria, including DNA-DNA relatedness, 16S rRNA gene sequence similarities, fatty acid profiles, whole-cell-protein patterns and multilocus enzyme electrophoresis profiles, as well as morphological, physiological and biochemical characterization. The analysis confirmed that these isolates belong to a novel species within the genus Burkholderia, for which the name Burkholderia silvatlantica sp. nov. is proposed. The type strain, SRMrh-20(T) (=LMG 23149(T)=ATCC BAA-1244(T)), was isolated from the rhizosphere of maize var. Avantis A2345 cultivated in Seropédica, Rio de Janeiro.

Bacterial Proteins↗
PubMed2006

Diazotrophic burkholderia species associated with field-grown maize and sugarcane.

Until recently, diazotrophy was known in only one of the 30 formally described species of Burkholderia. Novel N(2)-fixing plant-associated Burkholderia species such as B. unamae, B. tropica, and B. xenovorans have been described, but their environmental distribution is scarcely known. In the present study, the occurrence of N(2)-fixing Burkholderia species associated with different varieties of sugarcane and maize growing in regions of Mexico and Brazil was analyzed. Only 111 out of more than 900 isolates recovered had N(2)-fixing ability as demonstrated by the acetylene reduction assay. All 111 isolates also yielded a PCR product with primers targeting the nifH gene, which encodes a key enzyme in the process of nitrogen fixation. These 111 isolates were confirmed as belonging to the genus Burkholderia by using a new 16S rRNA-specific primer pair for diazotrophic species (except B. vietnamiensis) and closely related nondiazotrophic Burkholderia. In Mexico, many isolates of B. unamae (predominantly associated with sugarcane) and B. tropica (more often associated with maize) were recovered. However, in Brazil B. tropica was not identified among the isolates analyzed, and only a few B. unamae isolates were recovered from one sugarcane variety. Most Brazilian diazotrophic Burkholderia isolates (associated with both sugarcane and maize plants) belonged to a novel species, as revealed by amplified 16S rRNA gene restriction profiles, 16S rRNA gene sequencing, and protein electrophoresis. In addition, transmissibility factors such as the cblA and esmR genes, identified among clinical and environmental isolates of opportunistic pathogens of B. cenocepacia and other species of the B. cepacia complex, were not detected in any of the plant-associated diazotrophic Burkholderia isolates analyzed.

Brazil↗
PubMed2002

IGF-I, IGF-I-binding proteins and GH-binding protein in malnourished elderly patients with inflammation receiving refeeding therapy.

OBJECTIVE: To investigate the mechanisms determining the success or failure of refeeding therapy in malnourished elderly patients with inflammation by studying changes in plasma IGF-I, GH-binding protein (GHBP) and IGF-binding protein (IGFBP) levels and IGFBP-3 proteolysis. DESIGN AND METHODS: We studied 15 severely malnourished hospitalized elderly patients. Weight, food intake, plasma albumin, transthyretin, C-reactive protein (CRP), orosomucoid, interleukin-6 (IL-6), IGF-I, intact and proteolytically degraded IGFBP-3 and GHBP levels were determined on admission and during refeeding therapy designed to increase food intake to 40 kcal/kg body weight per day (15% protein). RESULTS: Plasma IGF-I, IGFBP-3 and GHBP levels were significantly low for age on admission in all malnourished elderly patients. They increased in nine patients as nutritional status improved (albuminemia >30 g/l; transthyretinemia >200 mg/l or weight gain >5% of initial body weight) and levels of inflammation markers decreased (group 1). In contrast, plasma IGF-I, IGFBP-3 and GHBP levels remained low in six patients in whom nutritional status failed to improve and levels of inflammation markers increased (group 2). IGF-I showed greater variations than IGFBP-3 or GHBP with respect to nutritional status. High plasma CRP and IL-6 levels were associated with high levels of IGFBP-3 proteolysis. CONCLUSION: Efficient refeeding therapy was associated with a significant increase in IGF-I plasma levels. In patients with severe and persistent inflammation, high levels of proteolysis of IGFBP-3 may have contributed to the low plasma IGF-I levels, persistence of hypercatabolism and lack of improvement in nutritional status.

Aged↗
PubMed2001

IGF type 1 receptor ligand binding characteristics are altered in a subgroup of children with intrauterine growth retardation.

The IGFs, IGF-I and IGF-II, regulate fetal growth by activating IGF type 1 receptors (IGF-IR). We aimed to quantify the binding of IGF-I to its cognate receptors in intrauterine growth-retarded children (IUGR). We measured the affinity of the erythrocyte IGF-IR and the number of IGF-IR receptors in 17 children with retarded growth (mean height, -2.7 SD), normal levels of GH, and a history of idiopathic intrauterine growth retardation (height at birth, -10 to -2 SD; mean, -3.1 SD). These children had reduced receptor affinity (Kd = 0.47 nM; P < 0.01) and more receptors per cell [binding capacity (Bmax) = 11.7 binding sites/cell; P < 0.05)] compared with control children (Kd = 0.32 nM; Bmax = 7.8 binding sites/cell). Moreover, the distributions of Kd and Bmax suggested that there were two groups of IUGR children. Group 1 included subjects with normal receptor binding function (Kd = 0.36 nM; Bmax = 8.2 sites/cell) and normal levels of circulating IGF-I. Group 2 comprised children with low receptor affinity (Kd = 0.56 nM) and increased receptor number (Bmax = 14.7 sites/cell). This group showed significantly decreased IGF-I levels (-2.1 SD; P < 0.01). We investigated these IGF-IR binding parameters in two additional groups of growth-retarded children (Turner syndrome and patients with chronic renal failure), in whom the IGF-I axis was not believed to be the primary cause, and found that Kd and Bmax were normal or nearly normal. We also measured IGF-IR binding parameters in 4 Seckel syndrome patients with IUGR and severely retarded growth (mean height, -7.9 SD). Their receptor affinity was reduced, but not statistically different, from that in controls, and their receptor number was normal, whereas IGF-I levels were elevated. Our results suggest heterogeneous alterations in IGF-IR binding function in IUGR patients.

Adolescent↗
PubMed2000

Insulin-like growth factor-I (IGF-I), insulin-like growth factor binding proteins (IGFBP) and insulin-like growth factor type I receptor in children with various status of chronic renal failure.

Chronic renal failure in childhood causes severe growth retardation. The aim of the study was to identify whether changes in the IGF system could account for the growth retardation observed in children with chronic renal failure. Insulin-like growth factor (IGF-I) serum concentrations, insulin-like growth factor binding proteins (IGFBP) and/or IGF-I binding to erythrocyte type I receptor of IGF were analysed in 69 children (mean age 11.6 +/- 4.3 years) with chronic renal failure and growth retardation (mean height -2.6 +/- 1.8 SD). The study population was separated into three groups, according to their renal status, children on conservative treatment (CRF group: n = 30), on haemodialysis (ESRD group: n = 26) and those transplanted (RT group: n = 13). Nineteen of these children, some from each of the three groups, received recombinant growth hormone therapy (rhGH). Mean basal IGF-I serum concentrations were -0.7 +/- 1.2 SD in the CRF group, + 2.1 +/- 3 SD in the ESRD group and + 1.1 +/- 2 SD in the RT group. Under rhGH therapy, as height velocity improved, mean IGF-I concentrations increased up to + 3.1 +/- 0.6 SD in the CRF group, to + 6.9 +/- 2.8 SD in the ESRD group and to + 3.9 +/- 2 SD in the RT group. Basal IGFBP-3 levels, studied by Western Ligand Blot were low in the CRF group and high in the ESRD and normal in the RT groups, whereas IGFBP-2 and a 30-32 kDa IGFBP were always high in all cases. Western immunoblot analysis showed that this 30-32 kDa IGFBP was mostly composed of IGFBP-1 and IGFBP-6 in all three groups, but IGFBP-6 was particularly abundant in the ESRD group. IGFBP-6 concentrations assessed by RIA were moderately increased in CRF children (392 +/- 177 ng/mL) and very high in children on ESRD (2094 +/- 1525 ng/mL) when compared to normal values (131 +/- 42 ng/mL). Binding studies of IGF type I receptor showed that there was no particular difference in IGF-I binding between renal failure patients and normal children. In poorly growing children, especially in ESRD children and to a lesser extent in RT children, high concentrations of IGF-I and IGFBP-1, 2, 3 and 6, suggest a resistance mainly by a sequestration mechanism. Moreover, in the CRF group, especially in the younger children, low levels of IGF-I and IGFBP-3 are evocative of an associated resistance at the GH receptor level.

Adolescent↗
PubMed2000

A targeted partial invalidation of the insulin-like growth factor I receptor gene in mice causes a postnatal growth deficit.

The insulin-like growth factor (IGF) system is a major regulator of somatic growth in vertebrates. Both ligands (IGF-I and IGF-II) signal via the same IGF receptor (IGF-IR). Classical IGF-IR invalidation is lethal at birth, so that conditional models are needed to study the postnatal role of this receptor. To establish a genetically inducible invalidation of IGF-IR, we targeted the IGF-IR gene using a construct that introduced a neomycin resistance cassette into intron 2, leaving the rest of the gene intact. This neomycin resistance cassette interfered with the processing of the primary transcript, resulting in there being 12% fewer IGF-binding sites at the cell surface in heterozygous mice and 41% fewer in homozygous mice. Hetero- and homozygous offspring grew more slowly than their wild-type littermates. This difference was noticeable from 4 weeks after birth and was significant from 5 weeks after birth in males. In females, the effect on postnatal growth of insertion of the neo cassette was not significant. In males, IGF-I levels increased moderately (+26%) but significantly, indicating effective feedback regulation of the IGF system. IGF-binding protein-4 (IGFBP-4) levels, estimated by Western ligand blotting, were low in homozygotes (-38%), whereas IGFBP-1, -2, and -3 levels were unaffected. In females, IGF-I and IGFBP-1, -2, -3, and -4 levels did not differ significantly among heterozygous, homozygous, and wild-type animals. We investigated the molecular mechanism involved and characterized two RNA-splicing events that could account for the decrease in IGF-IR. The phenotype of these mice developed exclusively postnatally, and body proportions were maintained. IGF-IRneo mice constitute a new model for human postnatal growth deficiency.

Animals↗
PubMed1999

Autocrine role of IGF-II in proliferation of human adrenocortical carcinoma NCI H295R cell line.

In adrenocortical tumors, the malignant phenotype is associated with rearrangements (paternal isodisomy) at the 11p15 locus and IGF-II gene overexpression, strongly suggesting that the IGF system is a major determinant of adrenocortical tumor progression. The aim of this study was to validate an in vitro model for investigating the involvement of the IGF system in adrenocortical tumorigenesis. We analyzed the production of IGF mRNA and proteins, IGF-binding proteins (IGFBPs) and IGF receptors by the NCI H295R cell line, which is derived from a human adult adrenocortical carcinoma. H295R cells were shown to proliferate for a long period (26 days) in the absence of serum or any added growth factor. Northern blot analyses showed high IGF-II mRNA contents in H295R cells. The cells secreted large amounts of IGF-II protein (14 ng/10(6) cells per 48 h) although no IGF-I protein was detected. Western ligand blot analyses of conditioned media detected the presence of large amounts of a 34 kDa protein, which was identified as IGFBP-2 by immunoblotting. The presence of high-affinity binding sites for IGF-I and IGF-II on H295R cells was shown by binding experiments using radiolabeled IGFs and confirmed by reverse transcription PCR analyses showing type 1 and type 2 IGF receptors. Proliferation of H295R cells was inhibited by anti-IGF-II antibody (45%) and by anti-type 1 IGF receptor antibody (53%) indicating that IGF-II is an autocrine growth factor for these cells and that its effects are, at least in part, mediated by the type 1 IGF receptor. These findings confirm the involvement of the IGF system in adrenocortical tumors and suggest that the H295R cell line is a suitable in vitro model for studying the molecular mechanisms of adrenocortical tumor proliferation.

Adrenal Cortex Neoplasms↗
PubMed1998

Increased levels of insulin-like growth factor II (IGF-II) and IGF-binding protein-2 are associated with malignancy in sporadic adrenocortical tumors.

In adrenocortical tumors, malignancy is strongly associated with insulin-like growth factor II (IGF-II) gene overexpression and abnormalities at the 11p15 locus, suggesting a role for this growth factor in adrenocortical tumorigenesis. To further investigate this role, the IGF/IGF-binding protein (IGFBP) system was analyzed in 18 adrenocortical tumors, classified into 2 groups on the basis of their IGF-II messenger ribonucleic acid (mRNA) content (group 1, normal IGF-II mRNA content, mostly benign tumors; group 2, high IGF-II mRNA content, mostly malignant tumors). Group 2 tumors contained 10 times more IGF-II protein than group 1 tumors or normal adrenal tissue (P < 0.001), indicating efficient translation of IGF-II mRNA in malignant tumors. Western ligand blotting detected various functional IGFBPs in normal adrenocortical glands and tumors: a doublet of 39-42 kDa identified by immunoblotting as IGFBP-3, a band at 32 kDa, and bands at 29-30 and 24 kDa. Total IGFBP-3 protein levels were similar in the two groups of tumors. By contrast, malignant tumors differed from benign ones by specific expression of the 32-kDa IGFBP. Immunoblotting identified this 32-kDa band together with a proteolytic fragment of 25 kDa as IGFBP-2, and quantitative analysis showed significantly higher levels of total IGFBP-2 in malignant tumors than in benign tumors (P < 0.001). Despite enhanced levels of IGBP-2 protein in malignant tumors, no increase in IGFBP-2 mRNA levels was detected, suggesting post-transcriptional regulation of this IGFBP. These results confirm the major role of IGF-II in adrenocortical tumorigenesis and suggest that IGFBP-2 may be a regulator of IGF-II proliferative effects in this tumor system.

Adolescent↗
PubMed1997

Insulin-like growth factors and their binding proteins in pleural fluid.

We investigated the expression and potential regulatory role of insulin-like growth factors (IGFs) and their specific binding proteins (BPs) in tuberculous and nontuberculous pleuritis. By using a radioimmunoassay after acid gel filtration chromatography, we found that mean concentrations of IGF-I were 211.9 +/- 20.2 microg/l and 203.2 +/- 31.1 microg/l in pleural fluid of 14 patients with tuberculous pleuritis and 9 patients with malignant pleuritis respectively. These values were near those in serum of the same patients (221.3 +/- 19.5 microg/l and 204.6 +/- 21.0 microg/l respectively). By using a specific protein-binding assay, we found that mean concentrations of IGF-II were 345.3 +/- 61.0 microg/l and 167.6 +/- 22.7 microg/l in tuberculous and malignant pleural effusions respectively. These values were significantly lower than those in serum of the same patients (628.3 +/- 79.0 microg/l, P<0.025 and 532.0 +/- 85.9 microg/l, P<0.025 respectively). Because bioavailability and bioactivity of IGFs may be regulated by their binding to IGFBPs, we studied IGFBP patterns in the pleural fluid of 6 patients with tuberculous pleuritis. As assessed by Western ligand blotting the levels of IGFBP-1 and IGFBP-2 were increased whereas those of IGFBP-3 were decreased in pleural fluid in comparison with serum. The decrease in IGFPB-3 levels reflected increased proteolysis, as assessed by Western immunoblotting. In spite of this presence of IGFBPs, IGFs could be responsible for the local biosynthesis of 1.25-dihydroxyvitamin D (1,25-(OH)2D) since pleural fluid levels of both IGF-I and IGF-II significantly correlated with those of 1,25-(OH)2D. These results indicate that IGFs are detectable in pleural fluid and may contribute to control the activity of 25-hydroxyvitamin D-1alpha hydroxylase in tuberculous pleuritis.

Adult↗
PubMed1994

IGFs and their binding proteins.

Insulin-like growth factors (IGFs), initially known as somatomedins, and their specific, high-affinity binding proteins (IGFBPs) are synthesized in most tissues, but principally in the liver. The interest of measuring their circulating levels, which reflect liver production, is to obtain indications as to their endocrine function and regulation. IGF-I plays a pivotal role in post-natal growth. Its half-life is significantly increased by its association with IGFBPs and its serum levels reflect somatotropic status, unlike growth hormone (GH) which has a much shorter half-life and whose secretion comes in pulses. Since investigation of growth retardation must include the most finely tuned appreciation possible of somatotropic secretion, assays of IFG-I and electrophoretic analysis of IGFBP profile can be useful tools, both diagnostically and therapeutically, and can help in determining the need or otherwise for GH treatment, especially in view of the growing demand for such therapy.

Growth Disorders↗
PubMed1994

Protease-induced alteration of insulin-like growth factor binding protein-3 as detected by radioimmunoassay. Agreement with ligand blotting data.

Structural alteration of insulin-like growth factor binding protein-3 (IGFBP-3) resulting from limited proteolysis by one or more serine proteases in vivo was first described in the serum of pregnant women and in certain pathological conditions. Western immunoblotting has since been employed to detect the phenomenon in normal serum, using a polyclonal antibody raised against recombinant human IGFBP-3 and a highly sensitive technique of visualization by chemiluminescence. The major proteolytic fragment of 30 kDa, which fails to be detected in native serum by ligand blotting owing to its weak affinity for IGFs, has proved clearly visible in all serum samples tested, sometimes accompanied by smaller fragments of 20 and 16 kDa. Among the serum samples analysed, increasing proportions of proteolysed IGFBP-3 were found in the following order: acromegalic patients, normal subjects, GH-deficient patients, pregnant women. In RIAs done with the same antibody, many of the serum samples yielded dose-response curves which were not parallel with standard curves, with lower gradients. In the samples where measurements were possible, apparent IGFBP-3 levels proved lower in pregnant women (2.28 +/- 0.23 mg/l, mean +/- SEM) than in normal adults (4.26 +/- 0.33 mg/l, P < 0.001). These observations, which contradict earlier reports of higher levels in pregnant women, suggest that the 30 kDa proteolytic fragment has a weaker affinity for the antibody than the intact IGFBP-3 (which in ligand- and immunoblotting appears as a characteristic 42-39 kDa doublet and which is barely or not detectable in pregnancy serum).(ABSTRACT TRUNCATED AT 250 WORDS)

Acromegaly↗
PubMed1993

The pneumotoxicant paraquat induces IL-8 mRNA in human mononuclear cells and pulmonary epithelial cells.

Paraquat (PQ) is a herbicide which is highly pneumotoxic by generating reactive oxygen intermediates (ROI). Pro-inflammatory cytokines, particularly IL-1 and TNF, have been implicated in some ROI-mediated pathologies, including bleomycin toxicity and ischaemia/reperfusion injury. We have studied the effect of PQ on the expression of the neutrophil chemotactic cytokine, IL-8, by human peripheral blood mononuclear cells (PBMC). While almost no IL-8 mRNA was detected in unstimulated cells, PQ (100 microM) induced high mRNA expression with a maximum at 24 h of incubation. While PQ did stimulate the appearance of IL-8 mRNA, no significant production of IL-8 protein was detected. However, PQ potentiated the production of IL-8 in the presence of 1 ng/ml of endotoxin (lipopolysaccharide, LPS). This was paralleled by an increased production of chemotactic activity for neutrophils, indicating that the IL-8 was actually bioactive. Stimulation of IL-8 mRNA by PQ was suppressed by IL-4 and by free radical scavengers (dimethylsulfoxide, mannitol). Increased IL-8 expression by PQ was also observed in the human pulmonary epithelial cell line A549 indicating that the effect of PQ was not specific for PBMC. These findings suggest that IL-8 might be involved in the pulmonary effects of PQ and that its production might be stimulated following an oxidative insult, and might clarify the pathogenetic mechanisms of adult respiratory distress syndrome (ARDS) or oxidant-induced pulmonary fibrosis.

Antioxidants↗
PubMed1992

A novel pharmacological approach for paraquat poisoning in rat and A549 cell line using ambroxol, a lung surfactant synthesis inducer.

Paraquat (PQ) is a widely used herbicide that causes acute adult respiratory distress syndrome (ARDS) and chronic lung damage (diffuse fibrosis). One of the earliest biochemical effects induced by PQ is damage to type II pneumocytes with consequent depletion of surfactant. With the aim of counteracting the toxic effects of PQ, a series of investigations were performed into the possible protective effect of the drug ambroxol, which induces the synthesis of surfactant in lung alveolar type II cells. The number of survivors and survival time of rats treated ip with 35 mg PQ/kg was significantly increased by 3 days of ambroxol pretreatment and by ambroxol treatment 30 min or 2 hr after PQ. Total phospholipid content in lung and bronchoalveolar lavage fluid (BALF) was significantly reduced 30 hr after treatment with PQ alone. The association of ambroxol with PQ significantly antagonized this reduction. In BALF the ratio between palmitic acid and stearic acid concentrations was significantly lower in animals treated with PQ alone but was returned to normal by the association with ambroxol. The cell line A549, exposed in vitro to PQ concentrations from 0.5 x 10(-4) to 2 x 10(-3) M, showed a significant dose-dependent loss of viability. Cells pretreated with ambroxol (10 mg/ml) were more resistant to PQ and their viability started to decrease significantly only from a PQ concentration of 0.8 x 10(-3) M. Membrane microviscosity was measured on the same cells. Cells treated with PQ alone showed a reduction of membrane microviscosity, which was significantly counteracted by ambroxol pretreatment. The curves of modification of membrane microviscosity of cells treated with PQ and with ambroxol plus PQ paralleled those of cell viability, indicating that the stimulation of surfactant synthesis in vitro may be a prerequisite for counteracting some of the early effects of PQ.

Adenocarcinoma↗
PubMed1991

Effects of exogenous insulin-like growth factor I on insulin-like growth factor binding proteins in a case of growth hormone insensitivity (Laron-type).

The electrophoretic profiles of serum insulin-like growth factor binding proteins (IGFBPs) from an 18-year-old patient with growth hormone (GH) insensitivity were analysed by Western ligand blotting before and after administration of recombinant human insulin-like growth factor I (IGF-I). Under basal conditions, the profile was the same as that observed in all cases of GH deficiency or insensitivity, that is, low IGFBP-3 (seen as two bands of 41.5 and 38.5 kDa) and enhanced IGFBP-2 and, to a lesser extent, IGFBP-1. Subcutaneous injection of IGF-I, 40 micrograms/kg, provoked an increase in serum IGF-I levels to close to the lower limits of the normal range and a small increase in IGFBP-3, suggesting that IGF-I has a direct effect on the synthesis of this GH/IGF-I-dependent IGFBP. Moderate increases were also observed in IGFBP-2 and IGFBP-4. Repeated doses of IGF-I over 7 days had no further effect on these changes, which persisted for a few days after the last injection.

Adolescent↗
PubMed1989

Membrane fluidity affects tumor-cell motility, invasion and lung-colonizing potential.

Membrane fluidity, determined by steady-state fluorescence polarization measurements, was correlated with metastatic capacity of murine tumor-cell lines. A correlation was observed in cell lines with different metastatic potential, and was confirmed when their lung-colonizing ability was modulated by alteration of either the membrane lipid composition or the culture conditions. Two cellular functions, motility and basement membrane invasion, were affected by the membrane lipid composition, and might explain the role of membrane fluidity observed in cancer metastasis.

Animals↗