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Biomedical subjects

A R Santos

Publications and source records attributed to A R Santos.

At least 19 recordsLinked to original sources
PubMed2006

Comparative sediment quality assessment in different littoral ecosystems from Spain (Gulf of Cadiz) and Brazil (Santos and São Vicente estuarine system).

The goal of this work was to establish comparisons among environmental degradation in different areas from Southern Spain (Gulf of Cádiz) and Brazil (Santos and São Vicente estuary), by using principal component analyses (PCA) to integrate sediment toxicity (amphipods mortality) and chemical-physical data (Zn, Cd, Pb, Cu, Ni, Co, V, PCBs, PAHs concentrations, OC and fines contents). The results of PCA extraction of Spanish data showed that Bay of Cádiz, CA-1 did not present contamination or degradation; CA-2 exhibited contamination by PCBs, however it was not related to the amphipods mortality. Ría of Huelva was the most impacted site, showing contamination caused principally by hydrocarbons, in HV-1 and HV-2, but heavy metals were also important contaminants at HV-1, HV-2 and HV-3. Algeciras Bay was considered as not degraded in GR-3 and -4, but in GR-3' high contamination by PAHs was found. In the Brazilian area, the most degraded sediments were found in the stations situated at the inner parts of the estuary (SSV-2, SSV-3, and SSV-4), followed by SSV-6, which is close to the Submarine Sewage Outfall of Santos - SSOS. Sediments from SSV-1 and SSV-5 did not present chemical contamination, organic contamination or significant amphipod mortality. The results of this investigation showed that both countries present environmental degradation related to PAHs: in Spain, at Ría of Huelva and Gudarranque river's estuary areas; and in Brasil, in the internal portion of the Santos and São Vicente estuary. The same situation is found for heavy metals, since all of the identified metals are related to toxicity in the studied areas, with few exceptions (V for both Brazil and Spain, and Cd and Co for Brazilian areas). The contamination by PCBs is more serious for Santos and São Vicente estuary than for the investigated areas in Gulf of Cádiz, where such compound did not relate to the toxicity.

Animals↗
PubMed2005

Use of blends of bioabsorbable poly(L-lactic acid)/poly(hydroxybutyrate- co-hydroxyvalerate) as surfaces for Vero cell culture.

Vero cells, a cell line established from the kidney of the African green monkey (Cercopithecus aethiops), were cultured in F-10 Ham medium supplemented with 10% fetal calf serum at 37 degrees C on membranes of poly(L-lactic acid) (PLLA), poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) and their blends in different proportions (100/0, 60/40, 50/50, 40/60, and 0/100). The present study evaluated morphology of cells grown on different polymeric substrates after 24 h of culture by scanning electron microscopy. Cell adhesion was also analyzed after 2 h of inoculation. For cell growth evaluation, the cells were maintained in culture for 48, 120, 240, and 360 h. For cytochemical study, the cells were cultured for 120 or 240 h, fixed, processed for histological analysis, and stained with Toluidine blue, pH 4.0, and Xylidine ponceau, pH 2.5. Our results showed that cell adhesion was better when 60/40 and 50/50 blends were used although cells were able to grow and proliferate on all blends tested. When using PLLA/PHBV (50/50) slightly flattened cells were observed on porous and smooth areas. PLLA/PHBV (40/60) blends presented flattened cells on smooth areas. PLLA/PHBV (0/100), which presented no pores, also supported spreading cells interconnected by thin filaments. Histological sections showed that cells grew as a confluent monolayer on different substrates. Cytochemical analysis showed basophilic cells, indicating a large amount of RNA and proteins. Hence, we detected changes in cell morphology induced by alterations in blend proportions. This suggests that the cells changed their differentiation pattern when on various PLLA/PHBV blend surfaces.

Animals↗
PubMed2005

A7445G mtDNA mutation present in a Portuguese family exhibiting hereditary deafness and palmoplantar keratoderma.

Mitochondrial DNA (mtDNA) A7445G point mutation has been shown to be responsible for familial nonepidermolytic palmoplantar keratoderma (NEPPK) associated with deafness without any additional features. To date, only a few cases have been described. We report a Portuguese pedigree presenting an inherited combination of NEPPK and sensorineural deafness compatible with maternal transmission. Clinical expression and age of onset of NEPPK and deafness were variable. Normal expression patterns of epidermal keratins and filaggrin, intercellular junction proteins including connexin 26, loricrin and cornified envelope proteins, were observed. Molecular analysis revealed that all the affected members, previously screened for Cx26 mutations with negative results, presented the mtDNA A7445G point mutation in the homoplasmic form. To our knowledge, this is the fifth family in whom inherited NEPPK and hearing loss are related to this mitochondrial mutation.

Adult↗
PubMed2004

Porous and dense poly(L-lactic acid) and poly(D,L-lactic acid-co-glycolic acid) scaffolds: in vitro degradation in culture medium and osteoblasts culture.

The use of bioresorbable polymers as a support for culturing cells has received special attention as an alternative for the treatment of lesions and the loss of tissue. The aim of this work was to evaluate the degradation in cell culture medium of dense and porous scaffolds of poly(L-lactic acid) (PLLA) and poly(D,L-lactic acid-co-glycolic acid) (50:50) (PLGA50) prepared by casting. The adhesion and morphology of osteoblast cells on the surface of these polymers was evaluated. Thermal analyses were done by differential scanning calorimetry and thermogravimetric analysis and cell morphology was assessed by scanning electron microscopy. Autocatalysis was observed in PLGA50 samples because of the concentration of acid constituents in this material. Samples of PLLA showed no autocatalysis and hence no changes in their morphology, indicating that this polymer can be used as a structural support. Osteoblasts showed low adhesion to PLLA compared to PLGA50. The cell morphology on the surface of these materials was highly dispersed, which indicated a good interaction of the cells with the polymer substrate.

Animals↗
PubMed2004

Tumor necrosis factor and interleukin-10 gene promoter polymorphisms in Brazilian population and in Terena Indians.

The Terena Amerindians are located in the midwestern region of Brazil. We have previously reported a restricted polymorphism for HLA class I and class II in 99 unrelated Terena using PCR-SSO and more recently for MICA. There are single nucleotide polymorphisms (SNPs) that determine high or low production of certain cytokines. We have now studied the frequencies of mutant allele (A) at position -308 in the promoter of the gene tumor necrosis factor (TNF)-alpha (pro-inflammatory cytokine) and the alleles A and T, at position -1082 and -819, respectively, in the promoter of the interleukin (IL)-10 gene, in 51 of these subjects from the Terena tribe using PCR SSP and in 195 normal unrelated healthy Brazilians using PCR-RLFP. All 51 Terena Indians tested (100%) had the G/G genotype at position TNF-alpha -308, with no mutation found thus far. In contrast, among the Brazilian general population, the allelic frequency of A was 18.9%. When anti-inflammatory cytokine IL-10 was studied at two different positions, -1082 and -819, a high mutation rate was found when Terena were compared with the general Brazilian population (P <.05). The genetic cytokine profile may be required to balance the restricted HLA repertoire for peptide presentation in this native population.

Brazil↗
PubMed2004

Interleukin-10 promoter single-nucleotide polymorphisms as markers for disease susceptibility and disease severity in leprosy.

We have determined IL-10 promoter genotypes of five single-nucleotide polymorphisms (SNPs): T-3575A, A-2849G, C-2763A, -A-1082G and C-819T. The haplotype frequencies were defined in healthy subjects compared to leprosy patients, and analyzed for their occurrence in multi- (MB) vs paucibacillary (PB) as severe and mild forms of leprosy, respectively. Haplotypes defined by three SNP positions (-3575, -2849 and -2763) captured significant differences between controls and patients (P=0.04). The haplotype carrying -3575A, -2849G and -2763C was associated with resistance to leprosy and to the development of severe forms of the disease using either a binomial (controls vs cases, P=0.005, OR=0.35, CI=0.13-0.91) or ordinal (controls vs PB vs MB, P=0.006, OR=0.32, CI=0.12-0.83) model. By contrast, the IL-10 haplotype -3575T/-2849A/-2763C was found to be associated with susceptibility to leprosy per se (P=0.027, OR=2.37, CI=1.04-5.39), but not leprosy type. The data suggest that the IL-10 locus contributes to the outcome of leprosy.

Confidence Intervals↗
PubMed2003

Dexamethasone and fetal calf serum effects in differentiation of Vero cells cultured on type I collagen gel.

Vero cells, a fibroblastic cell line, were cultured on a collagen I gel without fetal calf serum (FCS), with the addition of 10% FCS, 10% FCS plus dexamethasone (DEX) or 20% FCS. Our objective was to determine the effects of DEX on the differentiation pattern of fibroblastic cells cultured on a collagen substrate. We found that cells cultured with or without 10% FCS were capable of migrating into the collagen matrix. Near the cells in the gel, we found the deposition of extracellular granulations. Cytochemical data suggests that this material is glycosaminoglycans and/or proteoglycans. Surrounding the cells, a fibronectin deposition was found in the collagen. Thus, these cells make up a structure similar to a loose connective tissue. On the other hand, cells cultured with 10% FCS plus DEX or with 20% FCS did not invade the collagen matrix but formed multiple cell layers poor in fibronectin. On collagen I gel surface, we found an acellular layer rich in collagen IV, which appeared between the cells and the substrate. Thus, DEX or 20% FCS, furnished to the cells cultured on a collagen gel, block cell migration into the substrate and induce them to produce a basement membrane-like structure.

Animals↗
PubMed2002

Adhesion and morphology of fibroblastic cells cultured on different polymeric biomaterials.

Cell adhesion is influenced by the physical and chemical characteristics of the materials used as substrate for cell culturing. In this work, we evaluated the influence of the morphological and chemical characteristics of different polymeric substrates on the adhesion and morphology of fibroblastic cells. Cell growth on poly (L-lactic acid) [PLLA] membranes and poly(2-hydroxy ethyl methacrylate) [polyHEMA], poly(2-hydroxy ethyl methacrylate)-cellulose acetate [polyHEMA-CA] and poly(2-hydroxy ethyl methacrylate)-poly(methyl methacrylate-co-acrylic acid) [polyHEMA-poly(MMA-co-AA)] hydrogels of different densities and pore diameters was examined. Cells adhered preferentially to more negatively charged substrates, with polyHEMA hydrogels being more adhesive than the other substractes. The pores present in PLLA membranes did not interfere with adhesion, but the cells showed a distinctive morphology on each membrane.

Journal Article↗
PubMed2001

Antinociceptive properties of chalcones. Structure-activity relationships.

Eleven chalcones were prepared and tested as antinociceptive agents using the writhing test in mice. Some compounds, given intraperitoneally, caused potent and dose-related antinociception, being several times more active than some reference drugs. The results evidenced that some physico-chemical parameters are involved in the pharmacological activity. 3,4-Dichlorochalcone (2) was the most effective compound, and was also studied in another model of pain in mice, the formalin test. Here it inhibited only the inflammatory pain (second phase), being equipotent to the reference drugs.

Acetic Acid↗
PubMed2001

Vero cell growth and differentiation on poly(L-lactic acid) membranes of different pore diameters.

In the last few years, the demand has increased for research on polymeric materials, which can be used as substitutes for injured tissues and organs or to improve their regeneration. In this work, we studied poly(L-lactic acid) (PLLA) membranes, a resorbable biomaterial, which were either dense or had different pore diameters (less than 45 microm, between 180 and 250 microm, and between 250 and 350 microm), in relation to stimulation of cell adhesion, growth, and differentiation in vitro. We used Vero cells, a fibroblastic cell line, as the biological model of investigation. We found that cells attached slowly to all PLLA membranes studied. On the other hand, once the adhesion occurs, the cells are able to grow and differentiate on the different polymers. The cells grew to form a confluent monolayer and were capable of producing collagen Type IV and fibronectin on different PLLA membranes. This behavior indicates that cells try to create a better environment to stimulate their growth. This also indicates that Vero cells alter their differentiation pattern once they are producing extracellular matrix molecules related to epithelial differentiation.

Absorbable Implants↗
PubMed2001

Biological activity of plant extracts: novel analgesic drugs.

The plant-derived secondary metabolites have, over the years, greatly contributed to our current understanding of the important mechanisms related to the process of pain transmission and treatment. Furthermore, they have permitted us to characterise receptor types and identify endogenous ligands involved in the mechanism of nociception. In this review, we discuss the recent advances that have occurred regarding plant-derived substances in the process of development of new analgesic drugs. Plants, such as Papaver somniferum, Cannabis sativa and those of the Capsicum and Salix species, have greatly accounted for the development of clinically relevant drugs which are useful for the management of pain disorders. The recent advances in our understanding of the mechanisms of action of the above plant-derived substances, together with use of molecular biology techniques, have greatly accelerated attempts to identify promising targets for the discovery of new, safe and efficient analgesic drugs. Despite the great progress which has occurred in the elucidation of pain transmission and despite decades of use, leaving aside its known undesirable sides effects, morphine continues to be one of the most used drugs in clinical practice for the treatment of pain disorders. Thus, safer and more efficacious analgesic drugs are urgently needed. A search through the literature reveals that many potentially active antinociceptive plant-derived compounds have been identified. However, studies aiming to investigate their cellular and molecular mechanisms of action and well-controlled clinical trials to prove their efficacy in humans are still lacking. Nevertheless, natural or synthetic substances that bind to vanilloid or cannabinoid receptors, or even those that are capable of modulating the endogenous ligands which bind to these receptors, are expected to soon appear to assist in the treatment of several pain disorders, including those of neuropathic or neurogenic origin.

Journal Article↗
PubMed2001

Behaviour of fibroblastic cells cultured in collagen I using the sandwich technique.

Vero cells, a fibroblastic lineage derived from fibroblastic kidney cells of the African green monkey, were cultivated by means of the sandwich technique, involving glass coverslip/collagen and collagen/collagen with varied foetal calf serum concentrations in the culture medium. The cells, cultured on coverslips, then received a type I collagen gel layer on top, and migrated from the coverslip to the collagen layer. When the cells were cultivated on collagen followed by a covering of type I collagen gel, the cells migrated into both collagen layers. Cellular morphology was similar, independent of the type of sandwich and serum concentration used. Cells in contact with collagen either migrated into the layer or formed a basal lamina separating them from the collagen matrix. The formation of a basal lamina with laminin and collagen IV deposition was most noticeable when 20% foetal calf serum was used in the culture medium. Cellular infiltration into the collagen gel was most evident with the use of 10% foetal calf serum. The gel contraction was similar for the two serum concentrations employed.

Animals↗
PubMed2001

Detection of Mycobacterium leprae DNA by polymerase chain reaction in the blood of individuals, eight years after completion of anti-leprosy therapy.

Thirty eight patients with indeterminate leprosy (HI), at least 4 to 6 years after discharge from multibacillary (MB) or paucibacillary (PB) schemes of anti leprosy multidrug therapy (MDT), were submitted to traditional diagnostic procedures for leprosy and to polymerase chain reaction (PCR) analysis of different clinical samples for detection of Mycobacterium leprae DNA. No significant difference was observed for any of the parameters analyzed between PB or MB schemes of treatment and no indications were found for more efficient outcome of HI using the MB scheme. Remarkably, 18 (54.5%) of the individuals were PCR positive in at least one of the samples: positivity of PCR was highest in blood samples and four individuals were PCR positive in blood and some other sample. Upon comparison of PCR results with clinical and histopathological parameters, no correlation was found between PCR-positivity and eventual relapse. This is the first report on detection of M. leprae DNA in PB patients, more than half a decade after completion of MDT, suggesting that live bacilli are present and circulating much longer than expected, although reinfection of the individuals can not be excluded. Overall, we feel that because of the high sensitivity of the assay, extreme care should be taken about association of PCR results, efficacy of treatment and disease status.

DNA, Bacterial↗
PubMed2000

Differential schwann cell migration in adult and old mice: an in vitro study.

The influence of aging on Schwann cell (SC) proliferation, migration and viability was studied in vitro. SCs were cultured in Ham F-10 medium enriched with 20% fetal calf serum (FCS), 40% FCS or collagen I gel plus 20% FCS. The migration of adult mice derived SCs was stimulated with FCS and collagen. With aging, SC migration, multiplication and viability decreased, indicating that ideal culturing conditions should be adjusted.

Age Factors↗
PubMed2000

Antinociceptive properties of the methanolic extract and two triterpenes isolated from Epidendrum Mosenii stems (Orchidaceae).

The antinociceptive effect of the methanolic extract (ME) and two triterpenes isolated from E. mosenii (Orchidaceae) has been investigated in chemical and thermal models of nociception in mice. The ME of E. mosenii (0.3-30 mg kg(-1), i.p. or 50-400 mg kg(-1), p.o.) produced dose-related, significant and long-lasting (4 to 6 h) inhibition of acetic acid-induced abdominal constriction, with ID50 values of 3.9 and 137.0 mg kg(-1), respectively. Pholidotin and 24-methylenecycloartenol isolated from E. mosenii (0.1-3.0 mg kg(-1), i.p.) also produced marked and dose-related inhibition of acetic acid-induced pain, with ID50 values of 0.9 and 1.1 mg kg(-1). However, these compounds and the ME were about 3- to 13-fold more potent at the level of ID50 than diclofenac when assessed in acetic acid-induced abdominal constriction. The ME of E. mosenii in the same range of doses produced dose-related inhibition of both phases of formalin-induced licking, with mean ID50 values for the first and the second phases of 0.9, 122.0 mg kg(-1) and 0.7, 258.0 mg kg(-1), respectively by i.p. or p.o. routes. In addition, the ME (0.3-30 mg kg(-1), i.p., or 50-400 mg kg(-1), p.o.) also caused dose-related inhibition of capsaicin-induced neurogenic pain with mean ID50 values of 5.2 and 130.0 mg kg(-1), respectively. Treatment of animals with naloxone (5 mg kg(-1), i.p.) completely reversed the antinociceptive effect caused by morphine (5 mg kg(-1), s.c.) and that caused by ME of E. mosenii (1 mg kg(-1), i.p.) when assessed against either phase of the formalin-induced pain. Furthermore, when assessed in the hot-plate test, ME (100 mg kg(-1), i.p.) and morphine (10 mg kg(-1), s.c.) caused significant increase in response latency. However, ME given daily for to 7 consecutive days did not develop tolerance to itself nor did it induce cross-tolerance to morphine. Taken together these data demonstrate that the ME of E. mosenii elicited pronounced antinociception, when assessed by i.p. or p.o. routes, against several models of pain. Its actions involve, at least in part, an interaction with opioid system, seeming no to be related with a non-specific peripheral or central depressant actions. Finally, the active principle(s) responsible for the antinociceptive action of E. mosenii is likely related to the presence of the triterpenes.

Acetic Acid↗
PubMed2000

Naturally occurring antinociceptive substances from plants.

Despite the progress that has occurred in recent years in the development of therapy, there is still a need for effective and potent analgesics, especially for the treatment of chronic pain. One of the most important analgesic drugs employed in clinical practice today continues to be the alkaloid morphine. In this review, emphasis will be given to the important contribution and the history of Papaver somniferum, Salix species, Capsicum species and Cannabis sativa in the development of new analgesics and their importance in the understanding of the complex pathways related to electrophysiological and molecular mechanisms associated with pain transmission. Recently discovered antinociceptive substances include alkaloids, terpenoids and flavonoid. Plant-derived substances have, and will certainly continue to have, a relevant place in the process of drug discovery, particularly in the development of new analgesic drugs.

Analgesics↗
PubMed2000

Analgesic activity of cyclic imides: 1,8-naphthalimide and 1,4,5,8-naphthalenediimide derivatives.

In early studies, we have reported the synthesis and biological activities of several cyclic imides. The present study describes the analgesic activity of 1,8-naphthalimide and 1,4,5,8-naphthalenediimide derivatives in a standard murine model of analgesia. The pharmacological results show that all compounds studied, given intraperitoneally, produced significant inhibition of acetic acid-induced abdominal constrictions. At the ID50 (micromol/kg) level, these cyclic imide derivatives were about 40-270-fold more potent in this assay than aspirin and acetaminophen, two well-known and widely used analgesics. These results extend previous studies on the analgesic activity of cyclic imides.

1-Naphthylamine↗