Time filter

Source Type

MacLennan C.A.,University of Birmingham | MacLennan C.A.,University of Malawi | MacLennan C.A.,University of Liverpool | Gilchrist J.J.,University of Birmingham | And 28 more authors.
Science | Year: 2010

Nontyphoidal Salmonellae are a major cause of life-threatening bacteremia among HIV-infected individuals. Although cell-mediated immunity controls intracellular infection, antibodies protect against Salmonella bacteremia. We report that high-titer antibodies specific for Salmonella lipopolysaccharide (LPS) are associated with a lack of Solmonella-killing in HIV-infected African adults. Killing was restored by genetically shortening LPS from the target Salmonella or removing LPS-specific antibodies from serum. Complement-mediated killing of Salmonella by healthy serum is shown to be induced specifically by antibodies against outer membrane proteins. This killing is lost when excess antibody against Salmonella LPS is added. Thus, our study indicates that impaired immunity against nontyphoidal Salmonella bacteremia in HIV infection results from excess inhibitory antibodies against Salmonella LPS, whereas serum killing of Salmonella is induced by antibodies against outer membrane proteins. Source

Rivas-Santiago B.,Mexican Institute for Social Security | Rivas-Santiago C.,Rutgers University | Rivas-Santiago C.,Instituto Nacional Of Ciencias Medicas Y Nutricion Sz | Sada E.,Instituto Nacional Of Enfermedades Respiratorias | Hernandez-Pando R.,Instituto Nacional Of Ciencias Medicas Y Nutricion Sz
Immunotherapy | Year: 2015

Aim: Patients with pulmonary tuberculosis (TB) are the most important source for TB infection, being the risk of infection determined by the source case infectiousness and the contact closeness. Currently, the administration of isoniazid is used to prevent the infection to some extent in household contacts. At experimental level, defensins are efficient molecules for the treatment of TB and other infectious diseases. Materials & methods: In this work, we used a model of Mycobacterium tuberculosis transmission by long cohabitation of infected and noninfected mice, and treated the latter group with antimicrobial peptides in order to determine the potential capacity of defensins to prevent the infection. Results: Our results showed that the intratracheal administration of human neutrophil peptide-1, human β-defensin-2 alone or in combination and the use of L-isoleucine significantly prevents bacterial transmission, diminishing pulmonary lesions and bacterial loads. Conclusion: Data suggest the potential use of L-isoleucine as prophylactic for TB household contacts. © 2015 Future Medicine Ltd. Source

Montes-Cortes D.H.,Mexican Institute for Social Security | Hicks J.J.,National Institute of Respiratory Diseases Ismael Cosio Villegas
Metabolism: Clinical and Experimental | Year: 2010

Oxidative stress damage to biomolecules has been implicated in several diseases including diabetes mellitus. In the present study, we investigated the effect of oxidative stress in whole blood (WB) from diabetic patients (n = 60) on recombinant human insulin. Insulin was incubated with WB obtained from diabetic patients (DP) who had hyperglycemia (>300 mg/dL) or from 41 healthy volunteers (HV). Whole blood of DP, unlike WB of HV, induced higher values of formazan (142%), dityrosines (279%), and carbonyls (58%) in the insulin residues. Interestingly, the insulin modified by WB of DP showed less hypoglycemic activity in rat (30%) in comparison with insulin incubated with WB of HV. The incubation of insulin in WB from DP induces chemical changes in insulin and a decrease in its biological activity, events that might be associated with the high levels of oxidative stress markers found in the plasma of these patients. © 2010 Elsevier Inc. All rights reserved. Source

Perez G.,Mexican Institute for Social Security | Olivares I.M.,National Polytechnic Institute of Mexico | Rodriguez M.G.,University of Tlaxcala | Ceballos G.M.,National Polytechnic Institute of Mexico | Sanchez J.R.G.,National Polytechnic Institute of Mexico
Onkologie | Year: 2012

Background: Breast cancer is an important cause of cancerrelated death in women. In this pathological condition, arginase plays a role by providing ornithine as a substrate for the biosynthesis of polyamines which are important in tumor progression. The aim of this work was to determine the arginase activity in the plasma and tumors of patients with breast cancer; also, we investigated the relationship between this activity and the presence of the estrogen receptor. Patients and Methods: We evaluated the plasma arginase activity levels in 80 women with breast cancer and 42 healthy control subjects. We also measured the arginase levels in 42 breast cancer biopsies and 42 control tissues. Results: The mean activity of arginase in plasma was higher in breast cancer patients (0.78 nM/min/mg protein ± 0.04; p = 0.001) than in healthy volunteers (0.53 nM/min/mg protein ± 0.04); however, this difference was indicative of patients in the advanced stages of the disease (n = 38, stage III; p < 0.0001). In addition, we did not find a relationship between the estrogen receptor and arginase activity. Conclusion: Our results show a higher arginase activity in the plasma of patients in the advanced stages of the disease, suggesting that arginase activity could serve as a possible biological marker of breast cancer progression. © 2012 S Karger AG Basel. Source

Gutierrez-Escolano A.L.,CINVESTAV | Velazquez F.R.,Mexican Institute for Social Security | Escobar-Herrera J.,CINVESTAV | Saucedo C.L.,CINVESTAV | And 2 more authors.
Journal of Medical Virology | Year: 2010

Few studies exist regarding the frequency of human caliciviruses as single etiologic agents in sporadic cases, or in outbreaks occurring in children hospitalized for acute gastroenteritis. In this study, a total of 1,129 children of <5 years of age and hospitalized due to acute diarrhea were enrolled from three main hospitals in Mexico City during a period of 3 years (March 1998 to December 2000). After analyzing all fecal samples for several enteropathogens, 396 stools that remained negative were further screened for human caliciviruses by RT-PCR using a primer set specific to norovirus and sapovirus. Human caliciviruses were detected in 5.6% (22/396) of the children. The minimum incidence rate for 1999 were 5.3% (7/132) for 1999 and 7.8% (13/167) for 2000, since only fecal specimens that tested negative to other enteric pathogens were examined. Positive samples were further characterized using specific GI and GII primers and sequencing. Norovirus GII was detected in 19/22 samples, most of them were GII/4, while sapovirus GI/2 was detected in one sample. Associations between the presence of human calicivirus and clinical and epidemiological data revealed that diarrhea occurred with a seasonal pattern, and that children hospitalized due to human calicivirus disease scored an average of 13 ± 3.2 (SD) points on the Vesikari scale, which corresponded to severe episodes. These results highlight that human caliciviruses, by themselves, are enteropathogens of acute severe diarrhea among young Mexican children requiring hospitalization and that their detection is important in order to reduce the diagnosis gap. © 2010 Wiley-Liss, Inc. Source

Discover hidden collaborations