PubMed Health⌕ Search

Biomedical subjects

J Machado

Publications and source records attributed to J Machado.

At least 19 recordsLinked to original sources
PubMed2006

Illegal use of nitrofurans in food animals: Contribution to human salmonellosis?

Recent observations in Portugal of a remarkable incidence (65%) of Salmonella isolates from several sources (predominantly human and poultry) with decreased susceptibility to nitrofurantoin (MIC > or =64 mg/L), mostly comprising serogroup D isolates of Salmonella Enteritidis belonging to different phage types, suggest that illegal use of nitrofurans, especially in the poultry industry, might have contributed to the selection and prevalence of S. Enteritidis in food animals, and consequently to human salmonellosis in Portugal. Indiscriminate use of nitrofurans might also be implicated in the emergence of two multiresistant Salmonella Typhimurium clones disseminated throughout the country.

Animal Husbandry↗
PubMed2005

Isolation, purification and characterization of glycosaminoglycans in the fluids of the mollusc Anodonta cygnea.

The isolation, purification and characterization of Anodonta cygnea haemolymph, and extrapallial fluid glycosaminoglycans (Gags), which have high calcium affinity, were carried out in order to better understand the process of nacreous shell biomineralization. Our results show the existence of two different Gags with similar contents in the two fluids, throughout the year, but with significant seasonal variations for both. In the winter months, we identified by electrophoresis, only one kind of Gag chain (hyaluronic acid) while two different Gags (hyaluronic acid and heparan sulphate-like) from both fluids of A. cygnea were found in summer months. Quantification showed the total Gag fractions of both fluids in average, at their highest concentration (79.8 mg/L) in the highest calcification summer period. In contrast, the period of the year with the lowest concentration of total Gags (54.6 mg/L) occurred during the winter when calcification is reduced. This significant decrease between seasons is correlated mainly with the sulphated fraction, being 37.1 mg/L in the summer while only 9.2 mg/L in the winter haemolymph. The present data suggest that a heparan sulphate-like Gag has a relevant role in the biomineralization mechanisms acting as the calcium carbonate nucleator in the shell.

Animals↗
PubMed2003

Trends in antimicrobial drug resistance in Salmonella enterica serotypes Typhi and Paratyphi A isolated in Europe, 1999-2001.

Results of antimicrobial sensitivity tests for strains of Salmonella enterica serotypes Typhi and Paratyphi A isolated from patients in ten European countries between 1999 and 2001 have been transferred electronically to the Enter-net surveillance hub. For Typhi between 22 and 29% of isolates were multiresistant (to four drugs or more) with decreased susceptibility to ciprofloxacin (MIC 0.25-1.0 mg/l) increasing from 20% in 1999 to 26% in 2001. Nineteen of 169 (11%) strains with decreased ciprofloxacin susceptibility were sensitive to nalidixic acid. For Paratyphi A multiple resistance increased from 9% in 1999 to 25% in 2001 and decreased ciprofloxacin susceptibility from 6 to 17%. Clinicians should be aware of the possibility of treatment failures when fluoroquinolones are used as the first-line drug for infections with Typhi and Paratyphi A, particularly for patients recently returning from areas where drug-resistant strains are endemic.

Anti-Bacterial Agents↗
PubMed2003

Molecular epidemiology of Salmonella enteritidis phage type 1b and 6a isolates in Portugal.

Salmonella enterica serotype Enteritidis is an important serovar comprising 76 % of Salmonella isolates in Portugal in 2001. For better understand the epidemiology of salmonellosis, a total of 47 isolates of S. Enteritidis phage type (PT) 1b and 6a were analysed by pulsed-field gel electrophoresis (PFGE) and genomic DNA was subjected to macro restriction with XbaI. For PT 1b isolates, only three different patterns were observed, and PT6a showed a total of 10 digestion patterns. Curiously, the main pattern among PT1b isolates seams quite similar to main pattern of PT6a isolates, but when the two patterns were analysed with Bionumerics, we observed that they exhibited some differences. It was concluded that, in 2001, there was one predominant pattern for PT1b and PT6a and, possibly, we were in presence of clonal strains that exists all over the country.

Bacteriophage Typing↗
PubMed2003

Antimicrobial drug resistance in isolates of Salmonella enterica from cases of salmonellosis in humans in Europe in 2000: results of international multi-centre surveillance.

The Enter-net surveillance system received results of antimicrobial sensitivity tests for isolates from over 27 000 cases of human salmonellosis in 2000 in 10 European countries. Almost 40% of isolates were resistant to at least one antimicrobial, with 18% multiresistant. Resistance to ampicillin, streptomycin, sulphonamides and tetracyclines was common, with over 20% of isolates resistant to at least one of these antimicrobials. Clinical resistance to ciprofloxacin was rare, with only 0.5% of isolates exhibiting such resistance (MIC >1.0 mg/l). Resistance to nalidixic acid coupled with a decreased susceptibility to ciprofloxacin (MIC 0.25-1.0 mg/l) was more common, with 14% of isolates showing these properties. Resistance to third-generation cephalosporins was rare with only 0.6% of isolates resistant to cefotaxime. In all countries multiple resistance was most common in Salmonella enterica serotype Typhimurium, with 51% of isolates multiresistant in total. In England and Wales multiple resistance was also prevalent in S. Virchow and S. Hadar, whereas in other countries multiple resistance was common in serotypes such as S. Blockley.

Anti-Bacterial Agents↗
PubMed2002

Cytometric, morphologic and enzymatic characterisation of haemocytes in Anodonta cygnea.

The haemocytes in bivalve mussels are involved in many processes such as lesion repair, shell repair, elimination of small particles and toxic substances. In Anodonta cygnea there are two categories of haemolymph cells, the granulocytes and hyalinocytes. Two groups of cells were identified by flow cytometry and morphological studies: one with larger size and granularity representing 75%, and another group of cells (25%) which were approximately half the size. The cytochemical reactions showed peroxidase activity in the larger cells and a weak prophenoloxidase activity in the smaller cells. These characteristics suggest that the most common haemocytes are granulocytes and hyalinocytes are less common. Enzymatic studies showed clear activities of few enzymes in different compartments of the mantle. Both haemocytes presented significant variations for alpha-manosidase and beta-glucurosidase activities depending on the acid or alkaline pH. Almost all were sensitive to the pH changes, mainly the beta-galactosidase in the haemolymph plasma. On the contrary, the same enzymatic analysis in the extrapallial elements showed more stabilised activities. The simulation of acidic and alkaline condition with the observation of significant morphological and enzymatic activity changes, allow us to speculate some functional role, mainly in the haemolymph elements. The granulocytes may be speculated to have intense involvement in the digestion of small residues with the formation of calcareous stores while the hyalinocytes are more responsible for the elimination of soluble cytotoxic compounds.

Animals↗
PubMed2001

Virulence genes and P fimbriae PapA subunit diversity in canine and feline uropathogenic Escherichia coli.

In this study, a total of 118 Escherichia coli strains isolated from dogs (93) and cats (25) with urinary tract infection (UTI) were tested in a multiplex polymerase chain reaction for the presence of adhesin-encoding genes (pap, sfa, and afa), hemolysin encoding genes (hly), cytotoxic necrotizing factor 1 (cnf1) and aerobactin (aer) genes. Virulence gene frequencies detected in those isolates which had been randomly collected (68 canine strains) were: 43% pap, 57% sfa, 1% afa, 44% hly, 41% cnf1 and 34% aer. These frequencies were much higher in the remaining 50 hemolytic strains of either cat or dog origin. Virulence factor associations in the 80 hemolytic strains studied revealed that 50/80 simultaneously had two adhesin genes (pap and sfa) and two cytotoxin genes (hly and cnf1), and 15/80 in addition had the aer gene. The major structural subunit and antigenic determinant of P fimbriae of uropathogenic E. coli is PapA. Polymorphism in this subunit was studied by an F antigen-specific papA allele polymerase chain reaction in 51 canine and 22 feline pap positive E. coli strains. The most prevalent canine papA alleles were F10 (39%), F15 (37%) and F12 (35%). In feline strains F15 (50%) was more frequent, other allele frequencies were F12 (45%), F14 and F10 (27%) and F16 (23%). Only nine canine and two feline strains were negative for one of the 11 serologically defined F types of P fimbriae. Three copies of the pap operon were found in 16/51 canine and 9/22 feline UTI E. coli pap positive strains. In this study, we show that a particular combination of virulence genes appears with high frequency in dog and cat urinary tract E. coli strains (pap, sfa, hly, and cnf1). In spite of the more frequent presence of F10, F12 and F15 papA alleles in this virulence gene combination, the occurrence of different papA alleles in strains where up to three copies of the pap operon are present accounts for the observed P fimbriae diversity.

Alleles↗
PubMed2001

Distribution of papG alleles among uropathogenic Escherichia coli isolated from different species.

The distribution of alleles I, II and III of the P adhesin gene papG among Escherichia coli isolated from urinary tract infections in humans, dogs and cats was studied by PCR. Allele I was present in 6% and 5% of the human and cat isolates. Allele II as such was present in 30% and 22%, or in association with allele III in 12% and 2% of the human and canine isolates, respectively. Allele III was present in 33% of the human strains and predominated largely over allele II in E. coli isolates from cystitis of animal origin (72% in dog and 95% in cat strains). The three different classes of the PapG adhesin have been suggested to play a role in host specificity, for example human versus canine specificity. Recent studies, however, showed papG III positive human and dog cystitis isolates to be largely indistinguishable. We found the Class II allele in animal isolates and detected for the first time in Europe the Class I allele in a different genetic background than the J96-like clonal group. Our findings show that uropathogenic E. coli isolates from different species can have the same papG alleles and thus may have zoonotic potential.

Adhesins, Escherichia coli↗
PubMed2001

PTEN-independent induction of caspase-mediated cell death and reduced invasion by the focal adhesion targeting domain (FAT) in human astrocytic brain tumors which highly express focal adhesion kinase (FAK).

Increased expression of focal adhesion kinase (FAK) was consistently observed in low- and high-grade astrocytomas and during glioblastoma progression after radiotherapy, but not in the more benign oligodendroglioma. In glioblastoma cell lines deficient for p53, p16(INK4A), and p14(ARF), FAK was inhibited in a dominant-negative manner by the focal adhesion targeting (FAT) domain, reducing invasion. In addition, caspase-3 activity was increased after serum withdrawal, or by cisplatin in the presence of serum, or upon loss of substrate attachment, and was in each case independent of PTEN status. Our results identify FAK as a potential target for anti-invasive strategies against infiltrating glioma cells.

Astrocytoma↗
PubMed2001

Loss of focal adhesion kinase (FAK) inhibits epidermal growth factor receptor-dependent migration and induces aggregation of nh(2)-terminal FAK in the nuclei of apoptotic glioblastoma cells.

In glioblastoma cells, inhibition of focal adhesion kinase (FAK) by the focal adhesion targeting domain attenuated epidermal growth factor receptor (EGFR) signaling, inhibiting epidermal growth factor-dependent migration. Although the EGFR-specific antagonist PD153035 increased caspase-3 activity, this was independent of FAK activity. Instead, the increase in apoptosis upon inhibition of FAK induced the aggregation of an NH(2)-terminal FAK fragment normally present in the nucleus. A recombinant NH(2)-terminal FAK construct was also targeted to the nucleus and aggregated in apoptotic cells upon coexpression with the focal adhesion targeting domain. Therefore, loss of FAK from the focal adhesions inhibits EGFR signaling at the cell membrane and transmits a proapoptotic signal to an NH(2)-terminal variant of FAK present in the nucleus.

Apoptosis↗
PubMed2001

Soluble interleukin-1 receptor--reverse signaling in innate immunoregulation.

Interleukin-1 (IL-1) is one of the most important proinflammatory cytokines, regulating immunological and inflammatory processes. It induces a very efficient and self-amplifying cytokine-network. The action of IL-1 must, therefore, be under tight control. Soluble IL-1 receptor was thought to be an efficient negative regulator of the IL-1 signaling system. However, recent studies in vitro and in vivo demonstrate that soluble IL-1 receptor can act as an agonist as well, inducing intracellular signaling events. This feature of soluble IL-1 receptor adds a new level of complexity to our understanding of ligand-receptor cross-talk and cell-to-cell communication.

Adjuvants, Immunologic↗
PubMed2001

Investigation and control of a large outbreak of multi-drug resistant tuberculosis at a central Lisbon hospital.

An increase in the number of new cases of tuberculosis (TB) combined with poor clinical outcome was identified among HIV-infected injecting drug users attending a large HIV unit in central Lisbon. A retrospective epidemiological and laboratory study was conducted to review all newly diagnosed cases of TB from 1995 to 1996 in the HIV unit. Results showed that from 1995 to 1996, 63% (109/173) of the Mycobacterium tuberculosis isolates from HIV-infected patients were resistant to one or more anti-tuberculosis drugs; 89% (95) of these were multidrug-resistant, i.e., resistant to at least isoniazid and rifampicin. Eighty percent of the multidrug-resistant strains (MDR) available for restriction fragment length polymorphism (RFLP) DNA fingerprinting clustered into one of two large clusters. Epidemiological data support the conclusion that the transmission of MDR-TB occurred among HIV-infected injecting drug users exposed to infectious TB cases on open wards in the HIV unit. Improved infection control measures on the HIV unit and the use of empirical therapy with six drugs once patients were suspected to have TB, reduced the incidence of MDR-TB from 42% of TB cases in 1996 to 11% in 1999.

AIDS-Related Opportunistic Infections↗
PubMed2000

Bacillary angiomatosis by Bartonella quintana in an HIV-infected patient.

Bacillary angiomatosis and bacillary peliosis are opportunistic infections caused by Bartonella henselae and Bartonella quintana, which occur in patients with late-stage infection. We report a case of bacillary angiomatosis in an HIV-infected patient with skin, bone, and probably liver involvement, The identification of the agent (B quintana ) was done by polymerase chain reaction in the skin specimen. The patient had complete regression of all lesions after a 6-month regimen of oral erythromycin.

AIDS-Related Opportunistic Infections↗