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Biomedical subjects

D García

Publications and source records attributed to D García.

At least 19 recordsLinked to original sources
PubMed2003

Mucosal immunogenicity of the hepatitis B core antigen.

The hepatitis B virus (HBV) core antigen (HBcAg) is a potent immunogen in animal models and humans and has been used as a carrier for several antigens, however, the mucosal immunogenicity of HBcAg or chimeric HBcAg proteins has been poorly studied and only using the truncated variant of the HBcAg. In this study we explored the mucosal immunogenicity in mice of the recombinant complete nucleocapside of HBcAg. The antigen was administered by different mucosal and parenteral routes. The antibody response in sera was evaluated after each immunization and mucosal lavages were tested with the final extraction. To characterize the immune response, the serum IgG antibody response was tested during six months and also the ratio IgG2a to IgG1 was determined. The results obtained evidenced that the mucosal immunogenicity of HBcAg depended on the administration route, being the intranasal (i.n.) route the one that generated the higher IgG responses in sera, similar in intensity and duration to parenteral administrations. The IgA response in mucosal washes was superior for nasally immunized mice compared to the rest of mucosal and parenteral groups. The nasal route also induced the higher IgG2a to IgG1 ratio, evidencing a Th1-like Ab subclass pattern. In addition to the high Ab responses, preliminary results of the cellular response induced by nasal administration evidenced the induction of strong lymphoproliferative responses in spleen cells.

Animals↗
PubMed2003

Pulsed electric fields cause sublethal injury in Escherichia coli.

AIMS: The objective was to investigate the occurrence of sublethal injury in Escherichia coli by pulsed electric fields (PEF) at different pH values. METHODS AND RESULTS: The occurrence of sublethal injury in PEF-treated E. coli cells depended on the pH of the treatment medium. Whereas a slight sublethal injury was detected at pH 7, 99.95% of survivors were injured when cells were treated at pH 4 for 400 micros at 19 kV. The PEF-injured cells were progressively inactivated by a subsequent holding at pH 4. CONCLUSIONS: PEF cause sublethal injury in E. coli. The measurement of sublethal injury using a selective medium plating technique allowed prediction of the number of cells that would be inactivated by subsequent storage in acidic conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: This work could be useful for improving food preservation by PEF technology and contributes to the knowledge of the mechanism of microbial inactivation by PEF.

Colony Count, Microbial↗
PubMed2002

Resveratrol modulates rat macrophage functions.

This study investigated the effects of trans-resveratrol (trans-3,4',5-trihydroxystilbene, RESV), a natural polyphenol from grapes with known antioxidant activity, on the respiratory-burst responses and phagocytic activity of rat macrophages. RESV at concentrations of 1-10 microM significantly and dose-dependently inhibited (a) the extracellular production of reactive oxygen intermediates (ROls) by resident peritoneal macrophages stimulated with phorbol 12-myristate 13-acetate (PMA) (a potent activator of protein kinase C, PKC) and (b) intracellular production of ROIs after opsonin-independent phagocytosis of Kluyveromyces lactis cells. Over the 10-100 microM concentration ranges, RESV likewise inhibited the production of reactive nitrogen intermediates (RNIs) by macrophages stimulated with thioglycollate. RESV concentrations above 10 microM also dose-dependently inhibited the phagocytosis of K. lactis cells. The results obtained demonstrate that RESV is a potent inhibitor of the antipathogen responses of rat macrophages and, thus, suggest that this agent may have applications in the treatment of diseases involving macrophage hyperresponsiveness.

Adjuvants, Immunologic↗
PubMed2002

Modulation of rat macrophage function by the Mangifera indica L. extracts Vimang and mangiferin.

Vimang is an aqueous extract of Mangiferia indica L., traditionally used in Cuba as an anti-inflammatory, analgesic and antioxidant. In the present study, we investigated the effects of Vimang and of mangiferin (a C-glucosylxanthone present in the extract) on rat macrophage functions including phagocytic activity and the respiratory burst. Both Vimang and mangiferin showed inhibitory effects on macrophage activity: (a) intraperitoneal doses of only 50-250 mg/kg markedly reduced the number of macrophages in peritoneal exudate following intraperitoneal injection of thioglycollate 5 days previously (though there was no significant effect on the proportion of macrophages in the peritoneal-exudate cell population); (b) in vitro concentrations of 0.1-100 microg/ml reduced the phagocytosis of yeasts cells by resident peritoneal and thioglycollate-elicited macrophages; (c) in vitro concentrations of 1-50 microg/ml reduced nitric oxide (NO) production by thioglycollate-elicited macrophages stimulated in vitro with lipopolysaccharide (LPS) and IFNgamma; and (d) in vitro concentrations of 1-50 microg/ml reduced the extracellular production of reactive oxygen species (ROS) by resident and thioglycollate-elicited macrophages stimulated in vitro with phorbol myristate acetate (PMA). These results suggest that components of Vimang, including the polyphenol mangiferin, have depressor effects on the phagocytic and ROS production activities of rat macrophages and, thus, that they may be of value in the treatment of diseases of immunopathological origin characterized by the hyperactivation of phagocytic cells such as certain autoimmune disorders.

Adjuvants, Immunologic↗
PubMed2002

Sib-parentage testing using molecular markers when parents are unknown.

The formulae for computing the so-called Sib Index using codominant alleles for (1) full-sib and (2) half-sib parentage are given. Hypothesis testing is based on the distribution of conditional likelihood ratio or Bayes' factor. Thresholds for rejecting the null hypothesis and P-values were obtained in function of the number of alleles and their frequency distributions. Simulations showed that a relatively low number of marker systems (e.g. 20) are enough to accept the hypothesis of sib parentage with a reasonable power for usual significance levels, but that a higher number would be necessary if full-sib against half-sib parentage is the contrast to be carried out. The effect of sampling variation on the allele frequencies on power calculations is also analysed.

Alleles↗
PubMed2002

Transient topographical disorientation.

Transient topographical disorientation (TTD) is a short-lasting inability to find one's way in a familiar environment, while the patient remains conscious and is able to recall what happened. We report the study of 10 patients with episodes of TTD, studied on the days following the last episode. The episodes of TTD could be separated into two types: the patients either reported difficulties in spatial orientation with preserved abilities to recognize landmarks and objects, or the difficulties appeared with the recognition of landmarks. Tests exploring spatial orientation, as well as higher visuoperceptive capacities were altered in most of the patients and brain SPECT showed hypoperfusion of the right hemisphere in all patients, which could also be demonstrated 2 years later in some cases. Altogether, our findings suggest that TTD is frequently associated with a more persistent right hemisphere dysfunction of unknown cause. This chronic alteration could represent either a sequel of the acute episode or a preexisting right hemisphere deficit, which inclined the acute insult to be manifested as TTD.

Adult↗
PubMed2001

[Bacteremia in patients discharged from the emergency unit].

BACKGROUND: To know the clinical and epidemiologic characteristics, the evolution and the rate of adequate empiric antibiotic treatment in adult patients with a bacteremia discovered after discharge from an emergency unit. PATIENTS AND METHOD: During 10 years (1989-1998), we registered the clinical and epidemiological data from patients with a bacteremia detected after discharge from emergency. The results were compared with those of patients admitted to hospital who had a community-acquired bacteremia. RESULTS: 85 patients were analysed (52 males), 45% aged over 70 years. Overall, they represented 13.9% of community-acquired bacteremias detected during the same period. Most frequent source was the urinary tract (69%) followed by an unknown source (12%). E. coli was isolated in 62% of cases. In 16 cases, treatment was considered incorrect. Three patients died. CONCLUSIONS: A non-worthless number of patients with bacteremia are discharged from the emergency unit, and 21% of them receive inadequate treatment. Fatal outcome is rare but avoidable in some cases.

Aged↗
PubMed2001

Blood flow rate and energy charge in the isolated perfused canine liver.

Background. Liver viability depends on blood flow rate, which varies among isolated perfused livers used in different studies. We aimed to identify the minimal blood flow capable of keeping the energy charge compatible with liver viability. Materials and methods. Isolated canine livers were assigned to different groups (n = 4) with blood flow rates of 0.5 (Group I), 1.0 (Group II), and 1.5 ml/g/min (Group III). Blood gases, hematocrit, and glucose were measured over 180 min. Nucleotides, serum osmolarity, and electrolytes were also measured. Morphological changes were recorded at the end of each experiment. Results. Acid-base balance was better in livers from Group III. Electrolytes, osmolarity, hematocrit, and glucose showed no differences. Higher energy charges correlated with higher blood flow rates. On histopathology, there was evidence of more hydrostatic pressure-related changes in Group III, with no difference in necrosis or inflammatory-related alterations. Conclusions. (1) Energy charge correlates strongly with blood flow rate. (2) A rate of 1.5 ml/g/min allows for a better electrolyte, osmolarity, and acid-base balance. (3) Morphological analysis is not a sensitive predictor of organ viability as assessed by energetic potential. (4) The minimal blood flow rate required to attain an energy charge above 0.75 is 1.33 ml/g/min.

Acid-Base Equilibrium↗
PubMed2000

p16(INK4a) gene alterations are frequent in lesions of mycosis fungoides.

Mycosis fungoides is usually an indolent disease that, after a variable period of time in a stable phase, evolves into a tumoral form with aggressive behavior. The molecular events that mark this progression remain essentially unknown to date, and this prompted us to investigate the hypothetical role of p16(INK4a) silencing in mycosis fungoides progression. We analyzed the three most frequent mechanisms of inactivation of the p16(INK4a) gene (deletion, promoter hypermethylation, and mutation) in nine cases with patch/plaque and tumoral lesions of mycosis fungoides. The existence of alterations was investigated by microsatellite analysis, methylation-specific polymerase chain reaction, and direct sequencing. Alterations of the p16(INK4a) gene were found in four of nine of the plaque lesions (hypermethylation in three samples and allelic loss in one sample) and seven of nine in the tumor lesions (hypermethylation in five samples and allelic loss in three samples). No case presented point mutations. Although a higher incidence of p16(INK4a) hypermethylation was observed in the cases that failed to achieve a complete remission, the limited size of our series prompted us to evaluate this finding cautiously. The results of this study therefore showed a common genetic alteration that is found more frequently in tumoral lesions than it is in plaque lesions of mycosis fungoides. It also offers data that could suggest a relationship between p16(INK4a) hypermethylation and unfavorable clinical outcome. Broader studies are needed to confirm both relationships.

Adult↗
PubMed2000

[Clinical and molecular characterization of autosomal recessive chronic granulomatous disease caused by p47-phox deficiency].

BACKGROUND: The cytosolic protein p47-phox (phagocyte oxidase) is one of the essential components of the superoxide generating system in phagocytes and its defect causes approximately 30% of the chronic granulomatous disease (CGD) cases. AIM: Two patients were studied, belonging to the same family, without a consanguinous background, in which deficiency or absence of superoxide generation was found together with recurrent and severe infections in one case and benign infections in the second. METHODS: The presence of gp91-, p67- and p47-phox in patients and controls was determined by Western Blot analysis of granulocytes. Sequencing of PCR amplified DNA was performed by an enzymatic method. RESULTS: Western Blot analysis showed normal expression of gp91 and p67 and absence of p47-phox. The molecular genetic study demonstrated a homocygotic dinucleotide GT (GT) deletion at the beginning of exon 2 of the p47-phox gene. The same mutation has been found in European, American and Japanese patients. CONCLUSIONS: The molecular characterization of this pathology done for the first time in Chile is important for diagnostic classification, patient prognosis, and adequate genetic advice and a possible future therapy.

Adolescent↗
PubMed1999

In vitro inhibition of the replication of haemorrhagic septicaemia virus (VHSV) and African swine fever virus (ASFV) by extracts from marine microalgae.

We have screened for in vitro inhibition of viral replication with extracts from the following marine microalgae: Porphyridium cruentum, Phaeodactylum tricornutum, Tetraselmis suecica, Chlorella autotrophica, Dunaliella tertiolecta, Dunaliella bardawil, Isochrysis galbana, Isochrysis galbana var Tiso, Ellipsoidon sp. and Tetraselmis tetrathele. We have used as viral models two enveloped viruses of significant economic importance, the viral hemorrhagic septicemia virus (VHSV) of salmonid fish and the African swine fever virus (ASFV). The aqueous extracts from P. cruentum, C. autotrophica and Ellipsoidon sp., produced a significant inhibition of the in vitro replication of both viruses in a dose-dependent manner. That this inhibition could be due to sulfated polysaccharides was suggested because the same pattern of viral inhibition was obtained by using exocellular extracts from microalgae enriched in these compounds and/or dextran sulfate of high molecular weight. However, the inhibition of viral replication did not correlate with the percentage of sulfatation of the exocellular polysaccharides. Extracts from marine microalgae may have prophylactic utility against fish and mammalian viral diseases.

African Swine Fever Virus↗
PubMed1999

Widespread atypical cutaneous Leishmaniasis caused by Leishmania (L.) Chagasi in Nicaragua.

Leishmania chagasi, the causative agent of visceral leishmaniasis (VL) in the Americas, has recently been associated with atypical cutaneous leishmaniasis (ACL) in Central America; however, little comprehensive information about this disease is available. Clinical, epidemiologic, and parasitologic characteristics of 252 ACL cases and 44 VL cases in Nicaragua were analyzed. Visceral leishmaniasis is primarily associated with malnourished children less than five years of age, whereas ACL is found predominantly in children greater than five years of age and young adults. Genetically similar parasites are associated with both disease manifestations. The sand fly Lutzomyia evansi, in addition to Lu. longipalpis, may be involved in transmission of L. chagasi to humans. Our results indicate that ACL is more prevalent than previously thought, affecting up to 10% of a local population. The fact that the same parasite appears to cause both ACL and the potentially fatal visceral disease suggests that the host immune response is critical in determining the outcome of L. chagasi infection. The public health implications of the wide-spread presence of L. chagasi are discussed.

Animals↗
PubMed1999

[Prospective study of 198 community acquired pneumonias in a general hospital].

BACKGROUND: Pneumonia is a common medical problem with a significant mortality and morbidity. It is the leading infectious disease in hospital admissions. We conducted a one year prospective study of the patients over 14 years of age that had been diagnosed of community-acquired pneumonia in our institution. The objective was to determinate the clinical characteristics and the aetiological agents of pneumonia in our geographic area and to know which factors are related with the evolution and prognosis of this disease. PATIENTS AND METHODS: A medical team evaluated and followed-up all the patients diagnosed of community-acquired pneumonia. Epidemiological, clinical, radiological and laboratory data were recorded. An attempt to obtain an aetiological diagnosis was done by means of sputum, blood cultures and serologic studies at admission and between third and fourth week later. In individualized patients invasive techniques were performed. We classified the patients in five groups according to previous criteria defined in the guidelines of our hospital based in age, the presence of an underlying disease and the severity in the initial presentation. RESULTS: 274 patients received an initial diagnosis of pneumonia, in 76 (28%) this initial diagnosis was not confirmed. The mean age of the remaining 198 was 55 years. 62% were men. 40% had an identifiable microbiological etiology. The main causal microorganism was Streptococcus pneumoniae followed by Mycoplasma pneumoniae. Gram stain and sputum culture were the most useful laboratory tests for the aetiological diagnosis. Blood cultures and serological test had a lower efficiency. There was no relationship between the clinical presentation, typical or atypical pneumonia, and the causal microorganism. Complications developed in 11% of the patients and the mortality rate was of 3%. CONCLUSIONS: There was a high rate of initial erroneous diagnoses of pneumonia. The epidemiological, clinical and roentgenographic characteristics were similar to other studies conducted in our country with a lower number of microbiological agents identified. Patients who were admitted at hospital only because their age or the presence of chronic disease had a good evolution. In this series patients with severe presentation also had a good prognosis. It would be interesting to investigate about which parameters could be useful as indicators of prognosis and evolution at initial presentation of pneumonia.

Adolescent↗
PubMed1997

The effects of a triterpene fraction isolated from Crataegus monogyna Jacq. on different acute inflammation models in rats and mice. Leucocyte migration and phospholipase A2 inhibition.

The plant Crataegus monogyna has action against cardiac insufficiency, angina and arrhythmia. The anti-inflammatory properties of the cycloartenol fraction from this plant have been investigated. Chromatographic fractionation of the hexane extract of Crataegus monogyna Jacq. (Rosaceae) furnished a triterpene fraction containing cycloartenol as the main component (80.87%). The anti-inflammatory activity of the fraction was tested against hind-paw oedema induced by carrageenan in rats. At the highest oral dose (40 mg kg-1) inhibition was 61.5 and 52.5% at 3 and 5 h respectively. In the mouse carrageenan peritonitis test, the triterpene fraction given orally inhibited peritoneal leucocyte infiltration (41.9, 64.7 and 89.4% at 10, 20 and 40 mg kg-1, respectively). The fraction also showed weak inhibition of phospholipase A2 (PLA2) in-vitro. These results suggest that the fraction containing cycloartenol as the main component exerts an important anti-inflammatory action in-vivo by reducing the oedema.

Animals↗