Biomedical subjects

A Contreras

Publications and source records attributed to A Contreras.

At least 19 recordsLinked to original sources

PubMed2006

Molecular characterization and phylogenetic study of Maedi Visna and Caprine Arthritis Encephalitis viral sequences in sheep and goats from Spain.

Small ruminant lentiviruses (SRLV) are widely spread in many countries, including Spain. However, little is known about the genetic characteristics of Spanish goat and sheep SRLV. In this study, segments from three genomic regions (pol, gag-p25 and LTR) were amplified using DNA isolated from three Spanish autochthonous sheep (one) and goats (two). Animals (one per flock) belonged to distantly located, single-species flocks (goat or sheep). Sequence analysis showed conservation of regions that are putatively relevant to viral survival. Sequences of Spanish goat and sheep SRLV were allocated into phylogenetic trees (phylograms) with known SRLV groups. The phylograms corresponding to the pol, gag-p25 and LTR regions analyzed presented a compatible topology. This showed that Spanish caprine and ovine SRLV sequences belonged to the A or D phylogenetic groups and were closer to sheep SRLV prototypes (A1 group) than to goat SRLV prototypes (B or C groups), according to the current classification [Shah, C., Boni, J., Huder, J.B., Vogt, H.R., Muhlherr, J., Zanoni, R., Miserez, R., Lutz, H., Schupbach, J., 2004a. Phylogenetic analysis and reclassification of caprine and ovine lentiviruses based on 104 new isolates: evidence for regular sheep-to-goat transmission and worldwide propagation through livestock trade. Virology 319 (1), 12-26]. It was not possible to amplify in the three genetic regions the expected fragment in additional Spanish caprine and ovine SRLV proviral DNA sequences with the PCR primers used. This suggests that there is heterogeneity at the primer binding site among Spanish SRLV sequences. It also illustrates the need to develop diagnostic tests that are sensitive in local breeds.

Amino Acid Sequence↗

PubMed2006

Occurrence and preliminary study of antimicrobial resistance of enterococci isolated from dairy goats in Spain.

The present study performed in Spain was designed to investigate the occurrence and antimicrobial resistance of enterococci in faecal and bulk tank milk samples from 222 healthy Murciano-Granadina dairy goats reared on 12 farms. Enterococci were isolated in 54.5% and 63.6% of the faecal and bulk tank milk samples, respectively. Enterococci were detected more frequently from goat kids (70%) than from replacement animals (44.4%) and adults (56.4%). Seven species were found in the faecal samples but the most common species detected were Enterococcus faecium (32.3%), Enterococcus faecalis (27.6%) and Enterococcus hiriae (22%). In contrast, only E. faecium and E. faecalis were found in the bulk tank milk samples. According to NCCLS (2002), of the 134 strains studied, 17 (12.7%) were resistant to at least 7 antimicrobials and 14 of these strains were resistant to vancomycin.

Animals↗

PubMed2006

Periodontitis is associated with preeclampsia in pregnant women.

BACKGROUND: Recent investigations have demonstrated a positive association between periodontitis and pregnancy complications. The purpose of this study was to determine the effect of periodontitis and the subgingival microbial composition on preeclampsia. METHODS: A case-control study was carried out in Cali, Colombia that included 130 preeclamptic and 243 non-preeclamptic women between 26 to 36 weeks of pregnancy. Sociodemographic data, obstetric risk factors, periodontal status, and subgingival microbial composition were determined in both groups. Preeclampsia was defined as blood pressure>or=140/90 mm Hg, and >or=2+ proteinuria, confirmed by 0.3 g proteinuria/24 hours of urine specimens. Controls were healthy pregnant women. Odds ratios (ORs) for periodontitis and subgingival microbiota compositions were calculated. RESULTS: A total of 83 out of 130 preeclamptic women (63.8%) and 89 out of 243 controls (36.6%) had chronic periodontitis (OR: 3.0; 95% confidence interval (CI): 1.91 to 4.87; P<0.001). Clinical attachment loss increased in the case group (4.0+/-0.10 mm) compared to the control group (3.0+/-0.08 mm) (P<0.001). The average newborn birth weight from preeclamptic mothers was 2.453 g, whereas in controls was 2.981 g (P<0.001). Two red complex microorganisms, Porphyromonas gingivalis and Tannerella forsythensis, and the green complex microorganism Eikenella corrodens were more prevalent in the preeclamptic group than in controls (P<0.01). CONCLUSIONS: Chronic periodontal disease and the presence of P. gingivalis, T. forsythensis, and E. corrodens were significantly associated with preeclampsia in pregnant women. Further research is needed to establish pathogenic mechanisms of active periodontal disease and subgingival periodontopathogens related to preeclampsia development.

Adolescent↗

PubMed2005

Serotypes, virulence genes and intimin types of verotoxin-producing Escherichia coli and enteropathogenic E. coli isolated from healthy dairy goats in Spain.

Faecal samples from 222 healthy dairy goats on 12 farms in Spain, as well as bulk tank milk samples of these farms, were screened for the presence of verotoxin-producing Escherichia coli (VTEC) and enteropathogenic E. coli (EPEC). VTEC and EPEC were isolated in 47.7 and 7.7% of the animals, respectively. VTEC were isolated more frequently from adults and replacement animals than from goat kids. In contrast, EPEC were detected more frequently from goat kids than from replacement animals and adults. VTEC or EPEC strains were not detected in the bulk tank milk samples. Although a selective enrichment protocol was used, the serotype O157:H7 was not detected. The most frequent serotypes among the 106 VTEC strains isolated from goats were O5:H-, O76:H19, O126:H8, O146:H21, ONT:H- and ONT:H21. None VTEC strain was eae-positive. The absence of the eae gene in the VTEC strains could indicate that these strains are less virulent for humans that the classical eae-positive enterohaemorrhagic E. coli types. However, 16% of VTEC strains isolated from healthy goats belonged to serotypes associated with haemolytic uraemic syndrome in humans. The ehxA gene was detected in 84.9 and 52.9% of the VTEC and EPEC from goats, respectively. The beta1, theta/gamma2 and zeta were the most frequent intimin types among the 17 EPEC strains studied and the most prevalent serotypes of these strains were O156:H25 and O177:H11. Our data show that in Spain healthy goats are an important reservoir of VTEC and EPEC, and a potential source of infection for humans.

Adhesins, Bacterial↗

PubMed2005

Influence of storage and preservation on fossomatic cell count and composition of goat milk.

This study was designed to evaluate the effects of different test conditions on the somatic cell count (SCC) and composition of goat milk. To this end, 3600 tests were performed on 1800 aliquots taken from 40 goat milk samples using a combined instrument set-up based on flow cytometry for SCC and Fourier transform infrared analysis for fat, total protein, lactose, total solids, and freezing point determinations. The conditions tested were storage temperature (refrigeration and freezing), use of a preservative [no preservative (NP), azidiol (AZ), and bronopol (BR)], and age of the milk samples at each storage temperature (24 h to 42 d at refrigeration temperature and 21 to 105 d at freezing temperature). Significant effects on logSCC variation were shown by the storage temperature, the preservation treatment, the interaction of storage temperature x preservation treatment, and milk age within the interaction of storage temperature x preservative. Highest counts were recorded in the BR-preserved milk samples (logSCC = 5.877), and lowest counts were recorded in milk samples preserved using AZ (logSCC = 5.803). The use of frozen/thawed samples led to a significantly decreased logSCC for the treatments AZ and NP; the logSCC was not modified when BR-preserved frozen/thawed samples were analyzed. During storage, variations in the SCC observed for BR-preserved samples stored at refrigeration temperature for up to 25 d and at freezing temperature for all times tested were always < 10%. The preservation treatment was the main factor affecting the milk composition variables examined. Highest values of most variables were obtained in the BR-preserved samples, and the lowest values were obtained in the AZ-preserved samples. The freezing point was lower in the preserved samples than in the NP samples. The levels of milk constituents recorded in the BR-preserved samples were independent of both the storage temperature and age of milk sample. Our findings indicate that the freezing point of goat milk must be interpreted according to the preservative used.

Animals↗

PubMed2004

Influence of sampling time on bacteriological diagnosis of goat intramammary infection.

Intramammary infection in seven commercial goat herds was studied using premilking and postmilking samples for purposes as bacteriological diagnosis. Using a positive result on both premilking and postmilking samples as the definitive diagnosis, we compared the efficacy of single samples collected either premilking or postmilking. With this aim, 2268 bacteriological culture results were compared. The kappa values (0.60) showed moderate agreement between the two samples. Specificity and positive predictive value were higher for postmilking samples than for premilking samples. Specificity of postmilking samples was 99.4% for coagulase-negative staphylococci, 99.9% for Gram-negative bacilli, 100% for streptococci, 99.9% for corynebacteria and 100% for mixed cultures. Premilking samples specificity was 96.6, 99.5, 99.7, 99.8 and 99.8%, respectively. False positive diagnoses were more frequent for premilking samples. The results suggest that postmilking samples should be used to diagnosis of goat intramammary infection.

Animals↗

PubMed2004

Effect of clinical contagious agalactia on the bulk tank milk somatic cell count in Murciano-Granadina goat herds.

From 19 herds of Murciano-Granadina goats, weekly bulk tank somatic cell count (BTSCC) were performed from October to April, and suspicious milk (n = 182), synovial fluid, and ocular swabs (n = 15) from diseased goats were processed for mycoplasma isolation and identification. Also BTSCC from 65 herds were determined (n = 2693). A mixed model procedure was used to establish the effect of the herd and the lactation month on the BTSCC. Monthly rolling values were calculated for each herd using data collected over the preceding 3 complete months, and 4 different BTSCC thresholds were considered: 1,750,000, 1,500,000, 1,000,000, and 750,000 cells/mL. The mean log BTSCC for the 7-mo study period was 5.89 +/- 0.28 for herds without mycoplasma detection from clinical cases, 5.91 +/- 0.31 for mycoplasma-infected herds without clinical contagious agalactia (CA), and 6.47 +/- 0.32 for the herd with clinical CA. The posthoc tests revealed that only the herd that suffered a clinical CA outbreak showed counts that were significantly higher. No significant differences were found for BTSCC between herds not showing clinical episodes of CA, regardless of whether the mycoplasma had been isolated or not. The 1,750,000-cells/mL threshold would only be surpassed by a few herds with serious mastitis problems (clinical outbreak of CA for example). Seventy percent of the goat herds studied were in compliance with the proposed European Union legal limit of 1,500,000 cells/mL for goat milk.

Animals↗

PubMed2003

Identification and analysis of Escherichia coli proteins that interact with the histidine kinase NtrB in a yeast two-hybrid system.

In this work we used the yeast two-hybrid (Y2H) system to deepen our understanding of protein-protein interactions that are involved in the nitrogen regulatory network in Escherichia coli. Three different genes, encoding GlnB, GlnK and AspA, respectively, were found among 64 positive clones identified from E. coli Sau3AI Y2H libraries using the nitrogen regulator NtrB as bait. Structural and functional analysis of the prey clones provided information on library features and the degree of saturation achieved in the screens. Further analysis revealed that the C-terminal kinase domain of NtrB is required for the interaction with GlnK, while AspA(91-312) interacts specifically with the conserved histidine phosphotransfer domain of NtrB, thus providing additional evidence for the involvement of the conserved transmitter module of the histidine kinase NtrB in input sensory functions.

Escherichia coli↗

PubMed2003

Effect of freezing goat milk samples on recovery of intramammary bacterial pathogens.

With the aim of evaluating the effect of freezing goat milk samples on recovery of intramammary pathogens, 1200 milk samples from udder halves with subclinical intramammary infection were studied. Samples (20 ml) were frozen at -20 and at -80 degrees C. Thawing was carried out at room temperature at 7, 14, 21, 28, 58, 118, 178, 236 and 730 days after collection and bacteriological analyses were carried out to determine the number of colony forming units/ml (CFU/ml). Mixed model statistical analysis showed that bacterial group, temperature of storage, interaction of bacterial group and temperature of storage and the interaction of bacterial group, time and temperature of storage were statistically significant effects. For coagulase negative staphylococci (CNS), least squares means of log CFU/ml recovered at -20 and -80 degrees C were not different. Nevertheless, for Gram negative bacilli (GNB) a significant decrease was detected in samples frozen at -20 vs. -80 degrees C. At both temperatures and at different times of storage, significant increases were detected between log CFU/ml of CNS and values on day zero. At -20 degrees C, a significant decrease in GNB recovery was detected between freezing days zero and 730. This difference was not detected when goat milk samples infected by GNB were frozen at -80 degrees C. The results show that frozen milk samples can be useful in goat subclinical mastitis control programs.

Animals↗

PubMed2003

Polyclonal antibodies to xenogeneic endothelial cells induce apoptosis and block support of tumor growth in mice.

In this study, we demonstrate that vaccination of rabbits with murine endothelial cells yields polyclonal immunoglobulin (IgG) with potent antiangiogenic activity. The mechanism of this response appears to be through apoptosis of endothelial cells in vitro. Induction of polyclonal IgG in a xenogeneic host may be useful in passive immunotherapy of a variety of cancers. In fact, the antibody showed antitumor activity in three mouse tumor models (murine B16F10 melanoma, murine SVR angiosarcoma, and human DLD-1 colorectal adenocarcinoma). The polyclonal antibody generated here demonstrated utility in radioimaging of tumors in vivo, using positron emission tomography (PET) imaging, and suggested an antitumor effect in vivo. The results suggest that the antitumor effect in vivo may be related to antiangiogenic effects. Furthermore, anti-endothelial cell antibodies such as these could be useful reagents in isolating specific targets that comprise and induce the antiangiogenic effect.

3T3 Cells↗

PubMed2003

Factors constraining adherence to referral advice for severely ill children managed by the Integrated Management of Childhood Illness approach in Imbabura Province, Ecuador.

AIM: Low referral completion rates in developing countries undermine the Integrated Management of Childhood Illness (IMCI) strategy for lowering child mortality. This study sought to identify factors constraining adherence to referral advice in a health system using the IMCI approach. METHODS: Caregivers of 160 children urgently referred to hospital were prospectively interviewed. Caregivers who accessed and did not access hospital were compared for potential referral constraining factors, including demographics, family dynamics, the severity of their child's illness, their interaction with the health system, self-perceived problems, and physical and financial access. RESULTS: 67/160 (42%) referred children did not access hospital. Six factors were associated with non-access, including two health worker actions: not being given a referral slip [adjusted odds ratio (OR)= 15.3, 95% confidence interval (95% CI) 4.4-64.6] and not being told to go to the hospital immediately (adjusted OR = 5.3, 95% CI 1.9-16.3). Receiving both of these interventions reduced the risk of not accessing hospital to 19%, from 96% for those who received neither intervention. Several indicators of illness severity, including caregivers' ranking of their children's illness severity, the presence of severe illness signs and mortality, were investigated and found not to be important explanatory factors. CONCLUSION: Providing a referral slip and counseling the caregivers of severely ill children to go to the hospital immediately appear to be powerful tools for increasing successful referral outcomes.

Catchment Area, Health↗

PubMed2002

Treatment of Papillon-Lefèvre syndrome periodontitis.

BACKGROUND, AIMS: Conventional mechanical treatment of Papillon-Lefèvre syndrome periodontitis has a poor prognosis. This report describes an effective antimicrobial treatment of rapidly progressing periodontitis in an 11-year old girl having Papillon-Lefèvre syndrome. METHOD: Clinical examination included conventional periodontal measurements and radiographic analysis. Occurrence of major suspected periodontopathic bacteria was determined by selective and non-selective culture and by polymerase chain reaction (PCR) identification. Presence of cytomegalovirus and Epstein-Barr type 1 virus was determined by a nested-PCR detection method. Therapy included scaling and root planing, oral hygiene instruction, and systemic amoxicillin-metronidazole therapy (250 mg of each/3 times daily/10 days) which, based on follow-up microbiological testing, was repeated after 4 months. Supportive periodontal therapy took place at 2 visits during a 16-month period. RESULTS: At baseline, 10 of 22 available teeth demonstrated severe periodontal breakdown. At 16 months, probing and radiographic measurements revealed no teeth with additional attachment loss, and several teeth exhibited significant reduction in gingivitis and pocket depth, increase in radiographic alveolar bone height and clinical attachment level, and radiographic evidence of crestal lamina dura. Baseline subgingival microbiota included Actinobacillus actinomycetemcomitans (3.4% of total isolates), Prevotella nigrescens (16.4%), Fusobacteriumnucleatum (14.3%) and Peptostreptococcus micros (10.6%), as well as cytomegalovirus and Epstein-Barr type 1 virus. At termination of the study, culture and PCR examinations showed absence of A. actinomycetemcomitans, P. micros and herpesviruses, and P. nigrescens and F.nucleatum each comprised less than 0.1 % of subgingival isolates. CONCLUSION: This study suggests that controlling the periodontopathic microbiota by appropriate antibiotic and conventional periodontal therapy can arrest Papillon-Lefèvre syndrome periodontitis.

Aggregatibacter actinomycetemcomitans↗

PubMed2001

Relationships between infection with caprine arthritis encephalitis virus, intramammary bacterial infection and somatic cell counts in dairy goats.

Somatic cell counts, the bacteriological condition of the milk and antibodies against caprine arthritis encephalitis virus (CAEV) were measured monthly throughout lactation in 121 lactating goats of the Murcia-Granada breed in four commercial dairy goat herds. The prevalence of bacterial intramammary infection was 5.6 per cent and the prevalence of CAEV infection was 20.6 per cent. An analysis of variance revealed a significant effect of herd, intramammary infection and the interaction between intramammary infection and CAEV on the somatic cell count. In udder halves free of intramammary infection, the somatic cell counts were significantly lower in seronegative goats than in seropositive goats (P<0.05), but the difference was not significant in udder halves persistently infected by bacteria. There was a significant increase in somatic cell counts due to bacterial intramammary infection (P<0.01) in the seronegative goats, but this effect was not present in the seropositive animals.

Animals↗

PubMed2001

Statin-AE: a novel angiostatin-endostatin fusion protein with enhanced antiangiogenic and antitumor activity.

The combination of angiostatin and endostatin has been shown to have synergistic antiangiogenic and antitumor effects when the genes for these proteins are delivered to tumor cells by retroviral gene transfer. Here we report the construction of a murine angiostatin-endostatin fusion gene (Statin-AE) which shows enhanced antiangiogenic activity on human umbilical vein endothelial cell (HUVEC) tube formation in vitro compared with angiostatin or endostatin alone. Similarly, the fusion gene demonstrates antiangiogenic effects in vivo and antitumor activity in a B16F10 melanoma model when co-delivered by retroviral packaging cell inoculation in mice. The fusion gene demonstrates significantly greater inhibition of tumor growth compared with angiostatin, endostatin or the combination of genes.

Amino Acid Sequence↗

PubMed2001

Typing of herpes simplex virus from human periodontium.

Herpes simplex virus (HSV) is frequently detected in gingival crevicular fluid and in gingival biopsies of periodontal lesions; however, the relative occurrence of HSV type 1 and 2 in periodontal specimens has not been established. This investigation used type-specific polymerase chain reaction (PCR) to detect the presence of HSV-1 and HSV-2 in periodontal pocket samples from 26 patients who had previously been revealed to have periodontal HSV by PCR amplification of a gene shared by HSV-1 and HSV-2. HSV-1 was detected in all 26 periodontal pocket specimens and HSV-2 was not detected. Apparently, HSV-2 is a rare inhabitant of periodontal sites.

Adult↗

PubMed2001

Herpes viruses and periodontopathic bacteria in early-onset periodontitis.

OBJECTIVES: This study examined the occurrence of human herpes viruses and suspected periodontopathic bacteria in early-onset periodontitis patients who experienced progressive disease in at least 2 periodontal sites during the maintenance phase of therapy. MATERIAL AND METHODS: In each of 16 individuals (9 male and 7 female; mean age 33.1+/-2.6 years), subgingival plaque samples were collected from 2 deteriorating and 2 stable periodontitis sites. A nested polymerase chain reaction method determined the presence of human cytomegalovirus (HCMV), Epstein-Barr virus type 1 (EBV-1) and herpes simplex virus (HSV). A 16s rRNA polymerase chain reaction method identified Porphyromonas gingivalis, Dialister pneumosintes, Bacteroides forsythus and Actinobacillus actinomycetemcomitans. RESULTS: HCMV was detected in 59.4% of active and in 12.5% of stable sites (p<0.001), EBV-1 in 43.8% of active and in 12.5 % of stable sites (p=0.01), HSV in 34.5% of active and in 9.4% of stable sites (p=0.03), and co-infection with any of the 3 test herpesviruses in 43.8% of active and in 3.1% of stable sites (p<0.001). P. gingivalis was detected in 71.9% of active and in 37.5% of stable sites (p=0.01), D. pneumosintes in 62.5% of active and in 18.8% of stable sites (p=0.04), co-infection with P. gingivalis and D. pneumosintes in 50% of active and in 0% of stable sites (p<0.001), and co-infection with any 3 or 4 of the test bacteria in 40.6% of active and in 0% of stable sites (p=0.001). All periodontitis sites showing herpesvirus co-infection and all but one site showing P. gingivalis and D. pneumosintes co-infection revealed bleeding upon probing. CONCLUSIONS: HCMV, EBV-1, HSV and herpesvirus co-infection, as well as P. gingivalis, D. pneumosintes and P. gingivalis-D. pneumosintes co-infection were statistically associated with active periodontitis. Herpesviruses are immunosuppressive and may set the stage for overgrowth of subgingival P. gingivalis, D. pneumosintes and other periodontopathic bacteria. Understanding the significance of herpesviruses in human periodontitis may allow for improved diagnosis, more specific therapy and, ultimately, disease prevention.

Adult↗

PubMed2001

Herpesviruses in HIV-periodontitis.

BACKGROUND/AIMS: Human herpesvirus-associated diseases exhibit elevated morbidity and mortality in patients infected with human immunodeficiency virus (HIV). This study aimed to investigate the occurrence of herpesviruses in HIV-periodontitis. METHOD: Gingival biopsies from periodontitis lesions of 21 HIV-patients and 14 non HIV-patients were studied. Nested-polymerase chain reaction methods were employed to detect human cytomegalovirus, Epstein-Barr virus type 1 and 2 (EBV-1, EBV-2), herpes simplex virus, human herpes virus (HHV)-6, HHV-7 and HHV-8. RESULTS: Gingival biopsies from HIV-periodontitis lesions showed on average 4.0 herpesvirus species and gingival biopsies from HIV periodontitis lesions of non-HIV patients revealed an average of 1.9 herpesvirus species (p<0.001). Occurrence of 4 to 6 different herpesviruses was more common in HIV- than in non HIV-gingival biopsies (71% vs. 7%) (p<0.001). EVB-2 was detected in 12 (57%) biopsies from HIV-periodontitis but was absent in non HIV-periodontitis biopsies (p= 0.002). HHV-6 also occurred in significantly higher frequency in HIV-periodontitis (71%) than in non HIV-periodontitis (21%) (p=0.01). HHV-8 was detected only in biopsies from HIV-periodontitis lesions.. CONCLUSION: HIV-periodontitis seems to be associated with elevated occurrence of EBV-2, HHV-6 and herpesvirus co-infections compared to periodontitis in non-HIV-patients. The periodontopathic significance of herpesviruses in HIV-periodontitis constitutes a research topic of considerable interest.

AIDS-Related Opportunistic Infections↗

PubMed2001

Two-hybrid analysis of domain interactions involving NtrB and NtrC two-component regulators.

Signal transduction by two-component regulatory systems involves phosphorylation of the receiver domain of a response regulator by the transmitter domain of the cognate histidine kinase. In the NtrBC system, phosphorylation of NtrC by NtrB results in transcriptional activation of nitrogen-regulated genes. We have used the yeast two-hybrid system to probe interactions between domains of the NtrB and NtrC proteins from Klebsiella pneumoniae. We constructed fusions from each of a series of proteins or protein domains to the activation and the DNA-binding domains of GAL4 and analysed expression of GAL1:lacZ and GAL1:HIS3 reporters in yeast. The DNA-binding domain of NtrC and the so-called sensor domain of NtrB appeared to provide the major determinants for dimerization of the fusion proteins. A strong and specific interaction was also shown between NtrB and NtrC, localized to the HN region of the NtrB transmitter module and to the NtrC receiver domain, whereas other domains of these proteins do not appear to contribute to the recognition specificity. The results presented here indicate that communication between two-component partners also involves protein-protein interactions that can be detected in vivo, suggesting that the yeast two-hybrid system is a powerful genetic tool for identifying functional partners of prokaryotic signal transduction pathways.

Bacterial Proteins↗