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Biomedical subjects

A Guerrero

Publications and source records attributed to A Guerrero.

At least 91 records · Page 5Linked to original sources
PubMed2000

A new method for radioiodination of polysaccharides and its use in biodistribution studies of an immunomodulating glycoconjugate (Immunoferon).

A new method for the labeling of polysaccharides by using tyrosine derivatives after CNBr activation is presented, along with its use for pharmacokinetic studies of an orally active immunomodulating noncovalent glycoconjugate, which was administered labeled either in the polysaccharide or the protein moiety. The relationship between the obtained results and the mechanism of action are also discussed.

Adjuvants, Immunologic↗
PubMed2000

A 24-kDa cloned zinc metalloprotease from Actinobacillus pleuropneumoniae is common to all serotypes and cleaves actin in vitro.

Actinobacillus pleuropneumoniae causes pleuropneumonia in swine. This bacterium secretes proteases that degrade porcine hemoglobin and IgA in vitro. To further characterize A. pleuropneumoniae proteases, we constructed a genomic library expressed in Escherichia coli DH5alpha, and selected a clone that showed proteolytic activity. The recombinant plasmid carries an 800-base pair A. pleuropneumoniae gene sequence that.codes for a 24-kDa polypeptide. A 350-base pair PstI fragment from the sequence hybridized at high stringency with DNA from 12 serotypes of A. pleuropneumoniae, but not with DNA from Actinobacillus suis, Haemophilus parasuis, Pasteurella haemolytica, Pasteurella multocida A or D, or E. coli DH5alpha, thus showing specificity for A. pleuropneumoniae. The expressed polypeptide was recognized as an antigen by convalescent-phase pig sera. Furthermore, a polyclonal antiserum developed against the purified polypeptide recognized an A. pleuropneumoniae oligomeric protein in both crude-extract and cell-free culture media. This recombinant polypeptide cleaved azocoll, gelatin, and actin. Inhibition of the proteolytic activity by diethylpyrocarbonate suggests that this polypeptide is a zinc metalloprotease.

Actinobacillus Infections↗
PubMed1999

Microscopic and histochemical study of odontoclasts in physiologic resorption of teeth of the polyphyodont lizard, Liolaemus gravenhorsti.

Using tartrate-resistant acid phosphatase (TRAP), we examined the cytodifferentiation of odontoclast cells in resorbing areas of dental tissues during the replacement of teeth in a polyphyodont lizard, Liolaemus gravenhorsti. We also report, by means of Lectin-HRP histochemistry, the distribution pattern of some specific sugar residues of TRAPase-positive cells. For detection of TRAPase activity, the azo dye-coupling technique was used. Lectin binding sites were demonstrated by means of specific HRP-lectins. The process of tooth resorption was divided into four stages: 1) preresorption-the wall of the dental pulp is covered with an odontoblast layer, and no TRAP-positive cells are in the dental pulp; 2) early resorption-TRAP-positive multinucleate odontoclasts are present on the dental wall, but the rest of the pulp surface is still covered with an odontoblast layer; 3) later resorption-the entire surface of the pulp chamber is lined with multinucleate odontoclasts; and 4) final resorption-the tooth has been totally resorbed. Odontoclasts are usually detached from the resorbed surface, and show signs of degeneration. Of the six lectins used, PNA, ECA, and UEA-1 bind to multinucleated but not mononuclear cells. All the remaining lectins, BS-1, RCA(120), and LTA showed no binding to any cells of the teeth. The significance of saccharidic moieties such as acetyl-galactosamine, acetyl-glucosamine, and fucose sugar residues is difficult to ascertain. Perhaps these oligosaccharides might be borne on molecules associated with odontoclastic resorption or associated with multinucleation of odontoclasts after attachment to the dentine surface.

Acetylgalactosamine↗
PubMed1999

Mycobacterium kansasii infection in patients infected with the human immunodeficiency virus.

To investigate the clinical and radiographic features and the response to therapy of Mycobacterium kansasii infection in human immunodeficiency virus-infected patients, the clinical charts of 19 cases diagnosed during a 15-year period were reviewed retrospectively. Most patients were male intravenous drug abusers. Mycobacterium kansasii infection occurred late in the course of HIV disease and was associated with advanced immunosuppression. Thirteen patients had pulmonary disease, three extrapulmonary disease (2 with pulmonary involvement), and three pulmonary colonization. Most of them had fever and nonspecific respiratory symptoms; interstitial and alveolar infiltrates were the most common radiographic findings. Fourteen patients were given antituberculous treatment; among these, a clinical response was observed in 85%. Overall mortality was 63%, but only four patients died from active Mycobacterium kansasii disease. HIV infection has become the most important risk factor for Mycobacterium kansasii disease in our setting. Pulmonary infection is the most frequent form of disease and is usually responsive to antituberculous therapy.

AIDS-Related Opportunistic Infections↗
PubMed1999

Effect of thyroid status on lipid composition and peroxidation in the mouse liver.

In order to analyze the possible relationship between metabolic rate and oxidative stress, OF1 female mice were rendered hyper- or hypothyroid for 4-5 weeks by administration of 0.0012% L-thyroxine (T4) or 0.05% 6-n-propyl-2-thiouracil (PTU), respectively, in their drinking water. Treatment with T4 resulted in increased basal metabolic rate measured by oxygen consumption and liver cytochrome oxidase activity without altering the glutathione redox system. Endogenous lipid peroxidation, sensitivity to lipid peroxidation and fatty acid unsaturation were decreased in the hyperthyroid group. Hypothyroidism also decreased phosphatidylcholine and cardiolipin fatty acid unsaturation but not in total lipids, and thus lipid peroxidation was not altered. Cardiolipin, a mainly mitochondrial lipid, was the most profoundly altered fraction by both hyper- and hypothyroidism. It is suggested that the lipid changes observed in hyperthyroid animals can protect them against an increased oxidative attack to tissue lipids due to their increased mitochondrial activities.

Animals↗
PubMed1999

Zidovudine therapy protects against Salmonella bacteremia recurrence in human immunodeficiency virus-infected patients.

Fifty-five human immunodeficiency virus-infected patients with Salmonella bacteremia were studied to assess the rate of and causes for recurrence and to determine the influence on relapse of zidovudine, cotrimoxazole, and antimicrobial suppressive therapy according to the susceptibility of the isolates. Overall, 22% of patients relapsed in a median time of 87 days, independent of CD4 cell count, Salmonella serotype, or duration of antibiotic therapy. The use of zidovudine was associated with the lowest rate of recurrences compared with cotrimoxazole or amoxicillin as suppressive therapy. In the microbiologic assay, zidovudine showed bactericidal effect on Salmonella species at current dosages, and resistance to zidovudine was uncommon (2 cases, 4%). Due to its direct effect on Salmonella species, a zidovudine-containing regimen may protect against the recurrence of the disease.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Actographic analysis of the effects of an esterase inhibitor on male moth responses to sex pheromone.

The effects of 3-octylthio-1,1,1-trifluoropropan-2-one (OTFP), a trifluoromethyl ketone that inhibits antennal esterases, on male Mamestra brassicae responses to the main pheromone component have been investigated using an actograph. This actograph used a movement detector based on the Doppler effect. The signal from the detector was digitalized and analysed on a PC microcomputer to quantify male activity. When added to the air flowing through the observation chamber, OTFP inhibited the responses of male moths to the pheromone. The number of males responding to the pheromone and the intensity of the response were decreased by OTFP. The latency of the response was increased and its duration decreased. These effects on the kinetics of the behavioural response cannot be directly correlated to the inhibition of pheromone catabolism by OTFP and other targets must be involved. The high level of inhibition of behaviour observed in presence of OTFP demonstrates the interest of trifluoromethyl ketones as mating disruption agents for pest control.

Acetone↗
PubMed1999

Pheromone-triggered orientation flight of male moths can be disrupted by trifluoromethyl ketones.

In a wind tunnel trifluoromethyl ketones (TFMKs) have been found to disrupt the orientation flight of male moths to pheromone sources (virgin females or synthetic pheromone). This is demonstrated by comparison of the flight parameters of the Egyptian armyworm Spodoptera littoralis and the Mediterranean corn borer Sesamia nonagrioides, which had been topically treated with TFMKs, with those calculated for untreated insects. Inhibition occurred in all types of behavior and that of the source contact has been quantified and found to be dose-dependent. The same effect has also been noticed in Mediterranean corn borer males flying to an attraction source consisting of mixtures of (Z)-11-hexadecenyl trifluoromethyl ketone (8), a closely related analogue of the major component of the pheromone, and the natural pheromone blend. The most active TFMKs are those closest in structure to the natural pheromone, along with those chemicals which easily hydrate in solution, such as the beta-thiosubstituted derivatives. Along with the previously reported reduction of catches in the field, our results suggest the possible application of these chemicals in future new pest control strategies.

Animals↗
PubMed1999

Angiotensin II improves random-flap viability in a rat model.

Angiotensin II (AII) is a naturally occurring peptide that has been shown to be angiogenic, cause the proliferation of several primary cell types (including endothelial cells), accelerate the repair of dermal injuries, and increase production of growth factors and extracellular matrix. The effect of a single administration of AII on the viability and vascularity of a random flap was assessed in a rat model. In the control model, the viability of the distal portion of the flap was reduced consistently by postoperative day 8. Initially, AII was administered in an aqueous vehicle (phosphate-buffered saline [PBS]) and a viscous vehicle (10% carboxymethyl cellulose [CMC]). Administration of 1 mg per milliliter AII in PBS did not affect the viability of random flaps (1.2 x 7 cm) in this animal model. However, a single administration of a higher dose of AII in PBS (10 mg per milliliter) or 1 mg per milliliter AII in the CMC vehicle resulted in 67% of the grafts being fully viable at postsurgical day 12, in contrast to vehicle-treated control flaps, none of which were fully viable at day 12. Furthermore, the portion of the flap that was viable was increased significantly (p < or = 0.05). Subsequently, a study was conducted to assess the dose-response curve for AII in a CMC vehicle in this rat model. As the dose of AII was reduced, the percentage of animals with fully viable flaps and the percentage of the flap that was viable decreased correspondingly. Administration of 0.03 mg per milliliter AII and greater increased significantly (p < or = 0.05) the viability of the flaps. In conclusion, AII appears to be highly efficacious in increasing the percentage of distal flap surface area survival when administered as a single topical dose to the wound bed.

Analysis of Variance↗
PubMed1999

Value of PCR for detection of Toxoplasma gondii in aqueous humor and blood samples from immunocompetent patients with ocular toxoplasmosis.

Toxoplasma gondii infection is an important cause of chorioretinitis in the United States and Europe. Most cases of Toxoplasma chorioretinitis result from congenital infection. Patients are often asymptomatic during life, with a peak incidence of symptomatic illness in the second and third decades of life. Diagnosis is mainly supported by ophthalmological examination and a good response to installed therapy. However, establishment of a diagnosis by ophthalmological examination alone can be difficult in some cases. To determine the diagnostic value of PCR for the detection of T. gondii, 56 blood and 56 aqueous humor samples from 56 immunocompetent patients were examined. Fifteen patients with a diagnosis of ocular toxoplasmosis had increased serum anti-T. gondii immunoglobulin G levels but were negative for anti-T. gondii immunoglobulin M (group 1), and 41 patients were used as controls (group 2). Samples were taken before antiparasitic therapy was initiated, and only one blood sample and one aqueous humor sample were obtained for each patient. Single nested PCRs and Southern blot hybridization were performed with DNA extracted from these samples. The results obtained showed sensitivity and specificity values of 53. 3 and 83%, respectively. Interestingly, among all patients with ocular toxoplasmosis, a positive PCR result with the aqueous humor sample was accompanied by a positive PCR result with the blood sample. This result suggests that ocular toxoplasmosis should not be considered a local event, as PCR testing of blood samples from patients with ocular toxoplasmosis yielded the same result as PCR testing of aqueous humor samples. PCR testing may be useful for discriminating between ocular toxoplasmosis and other ocular diseases, and also can avoid the problems associated with ocular puncture.

Adolescent↗
PubMed1999

Transcription originating in the long terminal repeats of the endogenous mouse mammary tumor virus MTV-3 is activated in Stat5a-null mice and picks Up hitchhiking exons.

The enhancer within the long terminal repeats (LTRs) of acquired somatic mouse mammary tumor viruses (MMTV) can activate juxtaposed genes and induce mammary tumors. In contrast, germ line proviral MMTV genomes are integrated in the host genome and considered to be genetically confined transcription units. Here we demonstrate that transcription initiated in an MMTV provirus proceeds into flanking host sequences. We discovered multiple polyadenylated transcripts which are induced in Stat5a null mice. These range from 1.5 kb to more than 8 kb and are specifically expressed in mammary tissue from pregnant and lactating mice from the 129 but not C57BL/6 strain. The RNAs emanate from both LTRs of the endogenous MTV-3 provirus on chromosome 11 and proceed at least 10 kb into the juxtaposed genomic territory. Transcripts originating in the 5' LTR splice from the native splice site within the MMTV envelope gene into at least six exons, three of which contain functional internal splice sites. The combination of alternative splicing and the use of several polyadenylation sites ensure the generation of multiple transcripts. To date no significant open reading frame has been discovered. Furthermore, we demonstrate that transcription from the MMTV 5' LTR is highly active in the absence of Stat5a, a transcription factor that had been shown previously to be required for transcription from the MMTV LTR.

Animals↗
PubMed1999

Neurological complications after autologous stem cell transplantation.

INTRODUCTION: Autologous bone marrow (BMT) or peripheral blood stem cell transplantation (PBSCT) are increasingly used to treat hematological malignancies and solid tumors. The reported incidence of neurological complications varies greatly among the different centers, ranging from 11 to 39%. PATIENTS AND METHODS: In order to gain insight into the real incidence of early neurological complications (first 6 weeks) after autologous transplantation, we analyzed a series of 254 patients who underwent BMT/PBSCT for hematological malignancies (212 cases) or solid tumors (42 cases). RESULTS: Seven patients died during the early posttransplant period (incidence: 2.4%), and one of these deaths was related to a neurological complication. Eight patients developed neurologic complications (incidence: 2.8%). None of the patients developed cerebral hemorrhage during the early posttransplant period, despite a rather restrictive platelet transfusion support. Two out of 13 patients diagnosed AML and 3 out of 36 patients diagnosed Hodgkin's disease developed early neurological complications. DISCUSSION AND CONCLUSIONS: The neurological morbidity related to autologous transplantation was very low in our series of patients as compared to that reported in previous studies. This difference could be explained, at least in part, by a more restrictive definition of early neurologic complications.

Adolescent↗
PubMed1998

Improved outcome of cytomegalovirus retinitis in AIDS patients after introduction of protease inhibitors.

The objective of this study was to evaluate the influence of protease inhibitor therapy on the rate of progression and survival of 17 AIDS patients with stable Cytomegalovirus retinitis, who were receiving anti-CMV therapy. CD4+ count, HIV load, and CMV antigenemia assay were determined at baseline, at the first month, and every 3 months thereafter. Median CD4+ count increased from 11 to 87 cells/mm3, and median HIV RNA level decreased from 4.96 to 3.28 log10 copies/ml, after 6 months on therapy. Although 9 patients (53%) relapsed in a median time of 97 days (range, 15-152 days), no further episodes were observed during a median follow-up of 17 months (range, 5-18 months). Thus, the probability of remaining free of relapse was twofold higher than that observed in matched patients who did not receive protease inhibitors. Median CD4+ count at the 3rd month was higher in those individuals who went on to progress (p = .03), and a positive result to a CMV antigenemia test was associated with progression of retinitis (relative hazard, 4.45; p = .04). Survival rate was 94% at 17 months (89% increase). Therefore, protease inhibitor therapy reduces retinitis progression and improves survival. However, the immunologic response may not provide initial sufficient protection to avoid, or even may play a role on, early CMV progression.

AIDS-Related Opportunistic Infections↗
PubMed1998

Sex pheromone of the oleander scale, Aspidiotus nerii: structural characterization and absolute configuration of an unusual functionalized cyclobutane.

The sex pheromone emitted by the female oleander scale, Aspidiotus nerii (Homoptera, Diaspididae), has been isolated and characterized as (1R, 2S)-cis-2-isopropenyl-1-(4'-methyl-4'-penten-1'-yl)cyclobutaneethanol acetate by using advanced MS and NMR spectroscopic methods, as well as a variety of microderivatization sequences. The structure has been confirmed by stereo- and enantioselective synthesis of the four possible stereoisomers. The absolute configuration has been determined by comparison of the activity of the cis (1S,2R) and (1R, 2S) enantiomers with that exhibited by the natural material in greenhouse bioassays and field tests. The structure of this sesquiterpenoid pheromone is new in the coccids and in the pheromone field in general.

Journal Article↗
PubMed1998

Acrosome reaction inactivation in sea urchin sperm.

Acrosome reaction inactivation (ARI) is a process that renders sperm irreversibly refractory to the egg jelly (the natural inducer of the acrosome reaction, AR). This process triggered by the egg jelly, is associated with an increase in [Ca2+]i. However, we show here that a rise in [Ca2+]i alone is not sufficient to induce ARI, since artificially increasing [Ca2+]i with either an ionophore or rising external pH, does not trigger ARI. Contrary to the AR which strictly requires Ca2+, ARI can be triggered almost equally well by Sr2+. On the other hand, Mn2+ inhibits ARI and, as we showed earlier, does not affect AR. These observations indicate that the mechanisms involved in ARI differ from those leading to AR. In addition, we report here that high external pH (a non-physiological inducer of AR) triggers the AR in previously inactivated sperm by opening the same Ca2+ channels activated by the egg jelly. Considering that the opening of Ca2+ channels is one of the earliest responses triggered by the egg jelly and that ARI requires the egg jelly receptor to be activated, we have concluded that ARI involves the uncoupling between the egg jelly receptor and Ca2+ channels. Furthermore, intracellular pH (pHi) determinations, in the presence or absence of ionomycin to substitute for the uncoupled Ca2+ channels, indicate that pHi regulation is also impaired in inactivated sperm. In conclusion, ARI is a manifestation of the uncoupling of the egg jelly receptor from the different ion transport systems required for the acrosome reaction.

Acrosome↗
PubMed1998

Utility of anti-Hu antibodies in the diagnosis of paraneoplastic sensory neuropathy.

Anti-Hu antibodies (Hu-Abs) were positive in 40 patients with paraneoplastic sensory neuropathy (PSN) and in 1 patient with idiopathic sensory neuropathy in a series of 126 patients who presented with clinical features suggestive of PSN. The specificity of Hu-Abs was 99% and the sensitivity was 82%. Nine (18%) PSN patients were Hu-Ab-negative, and their sera did not harbor other specific anti-neuronal or anti-ganglioside antibodies. Small cell lung carcinoma (SCLC) was the leading neoplasm in the Hu-Ab-positive (79%) and Hu-Ab-negative (44%) groups. This study confirms the value of Hu-Abs for the diagnosis of PSN and SCLC and also emphasizes that in patients with possible PSN, the absence of Hu-Abs does not exclude cancer, particularly in those patients with risk factors for SCLC.

Adult↗