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M S Sanchez

Publications and source records attributed to M S Sanchez.

15 recordsLinked to original sources
PubMed2001

Effect of neuropeptide-EI on the binding of [3H]SCH 23390 to the dopamine D1 receptor in rat striatal membranes.

We have previously demonstrated that neuropeptide-EI, at high doses, stimulates the production of cAMP, in caudate putamen, through the activation of adenylate cyclase coupled to specific D1 receptors. The aim of the present work was to find evidences for a probable interaction between this neuropeptide and the dopamine D1 receptor in the mammalian central nervous system. The present data show that neuropeptide-EI, at high concentrations, affected both the maximum binding and the apparent affinity of [n-methyl-3H] (R)-(+)-8 chloro-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepin-7-ol hemimaleate to the dopamine D1 receptor in a concentration-dependent manner.

Animals↗
PubMed2000

Evidence that alpha-MSH induced grooming is not primarily mediated by any of the cloned melanocortin receptors.

It is well established that melanocortic peptides, such as melanocyte-stimulating hormone (MSH) and adrenocorticotropin, induce grooming behavior. The MC3 and MC4 receptors are the MC receptors which are most abundantly expressed in the brain. gamma-MSH, a peptide with preference to the MC3 receptor, however, does not induce grooming. Recent studies have shown that MC4 receptor antagonists are very effective in inhibiting alpha-MSH induced grooming. These data have indicated that grooming behavior in rodents may be mediated by the MC4 receptor. In this study we investigated if the recently developed MC1 receptor selective agonist MS05 was able to induce grooming in comparison with alpha-MSH. The results show that MS05 is effective in inducing grooming after either intracerebroventricular or ventral tegmental area administration in rats. Central administration of either MS05 or alpha-MSH besides grooming also induced stretching, yawning, rearing and locomotion. The results indicate that the earlier hypothesis that the MC4 receptor is the main mediator of grooming behavior has to be modified. Moreover, as this behaviour does not pharmacologically correlate to the profile of any of the five cloned MC receptors, we suggest that alpha-MSH induced grooming may not primarily be mediated by any of these receptors.

Animals↗
PubMed1999

The allotypic patchwork pattern of the rabbit IGKC1 allele b5wf: genic exchange or common ancestry?

The protein sequences of different alleles of the rabbit immunoglobulin IGKC1 gene can differ at more than 40% of the amino acid positions. This exceptional degree of allelic divergence raises questions concerning the causal underlying mechanisms. We report the DNA sequence of the coding region of an allotype which is associated with the mitochondrial lineage A (Southwestern Spain). At the serological level, this b5wf allotype presents a patchwork of antigenic determinants which in domestic breeds are characteristic of the b4, b5, and b6 allotypes. The inferred protein sequence of the b5wf allotype was found to differ from that of the b4, b5, and b6 allotypes at 25, 10, and 15% of the amino acid positions, respectively. Sequence comparisons show that the b4-specific epitopes of the b5wf allotype are probably due to a shared ThrThrGlnThr motif at Kabat positions 153-156. Similarly, the shared b5-specific determinants should relate to the motifs 161ThrSerLys163 and/or 182LysSerAspGlu185. A monoclonal antibody binding epitope shared among the b5wf, b5, and b6 sequences appeared to be correlated with the presence of Asp190. Although there is evidence of interallelic genic exchange, sequence comparisons suggest that the apparent mosaic structure of the b5wf allotype is better explained by common ancestry and point mutation.

Alleles↗
PubMed1999

Effects and interactions between alpha-MSH and MCH/NEI upon striatal cAMP levels.

It is known that alpha-MSH augments cAMP levels in rat brain slices containing accumbens and caudate-putamen nuclei. In this study we examined: a) the effect of other neuropeptides: MCH and NEI, on this cyclic nucleotide; b) if the effects of alpha-MSH on cAMP production can be modulated by addition of MCH or NEI to the incubation medium. Both MCH and NEI (3.6 microM) increased the production of cAMP, whereas at doses of 0.6 microM exerted no effects. When alpha-MSH 0.6 microM was added with NEI or MCH (0.6 microM), only MCH blocked the increase in the cAMP induced by alpha-MSH. Neither MCH nor NEI at the highest dose used (3.6 microM) had any additive effect on AMPc when added together with alpha-MSH. We conclude that, at a high concentration, (MCH/NEI)-like peptides can use the intracellular signal transduction linked to cyclic nucleotides in the CNS.

Animals↗
PubMed1999

Attenuation and immunogenicity of Deltacya Deltacrp derivatives of Salmonella choleraesuis in pigs.

Six different isogenic Deltacya Deltacrp derivatives of a strain of Salmonella choleraesuis var. kunzendorf-chi3246 virulent for pigs were constructed by transposon-mediated deletion mutagenesis. These strains were evaluated for virulence and ability to elicit a protective immune response in young weaned pigs after oral administration and were compared to a commercially available vaccine which lacks the 50-kb virulence plasmid (vpl(-)). These derivatives were Deltacya Deltacrp vpl(+), Deltacya Deltacrp vpl(-), Deltacya Delta(crp-cdt) vpl(+), Deltacya Delta(crp-cdt) vpl(-), Deltacya Deltacrp pmi-3834 vpl(+), and Deltacya Delta(crp-cdt) pmi-3834. In experiments to evaluate safety, no significant adverse effects of any of the vaccine constructs were observed, except that two of the strains which carried the virulence plasmid (vpl(+)) caused a small, short-term elevation in maximum temperature compared to pretreatment temperature values. Orally immunized animals, except for those vaccinated with the Deltacya Deltacrp pmi-3834 vpl(+) strain or SC-54, developed significant serum antibody responses 21 days postvaccination as measured by enzyme-linked immunosorbent assay. No cell-mediated immune responses to heat-killed S. choleraesuis were noted at the same time point as measured with heat-killed bacteria as antigen in a lymphocyte proliferation assay. In an oral challenge exposure model with a highly virulent heterologous strain of S. choleraesuis, the Deltacya Deltacrp strains with deletions in pmi were not protective. As measured by morbidity scores, the responses to challenge of the pigs vaccinated with the other four Deltacya Deltacrp derivatives were significantly better than those of the nonvaccinated, challenged group. With the exception of temperature elevation and slight differences in diarrhea scores postchallenge, none of these strains differed significantly from each other in the other clinical parameters analyzed. While the commercial vaccine was protective by most of the parameters measured, it was not fully protective against challenge with virulent S. choleraesuis as judged by diarrhea scores and temperature elevation. Collectively, these data demonstrate that Deltacya Deltacrp derivatives, with or without the virulence plasmid but not with deletions in the pmi gene, are candidates for vaccines for protection against salmonellosis in pigs.

Animals↗
PubMed1999

Enhancement of the activity of novobiocin against Escherichia coli by lactoferrin.

The activity of novobiocin against Escherichia coli ATCC 25922 and three E. coli strains that were isolated from cases of bovine mastitis was determined in timekill studies in the presence of bovine lactoferrin. Lactoferrin alone did not affect the growth of any of the strains of E. coli. A combination of 1.0 mg/ml of lactoferrin and novobiocin at 1/16x minimum inhibitory concentration (MIC) was bactericidal for E. coli ATCC 25922. When the concentration was increased to 3.0 mg/ml of lactoferrin, novobiocin was bactericidal at 1/64x MIC. Among the mastitis strains tested, 6789 and 6806 were more susceptible to killing by novobiocin than was strain 6800. Strains 6789 and 6806 were killed when treated with novobiocin concentrations of 2, 1/2, and 1/4x MIC. When these strains were also treated with lactoferrin at 3.0 mg/ml, there was a bacteriostatic effect at novobiocin concentrations of 1/8 and 1/16x MIC for strains 6789 and 6800. Strain 6806 appeared to be more susceptible to the combination of lactoferrin and novobiocin as was evidenced by a bactericidal effect over the 24-h testing period. The combination treatment with cephapirin and lactoferrin showed that there was a synergistic bactericidal effect against all of the E. coli strains tested. These studies indicate that lactoferrin can potentiate the activity of antibiotics against Gram-negative bacteria.

Animals↗
PubMed1997

In vitro activity of premafloxacin, a new extended-spectrum fluoroquinolone, against pathogens of veterinary importance.

The in vitro activity of premafloxacin against 673 veterinary pathogens was evaluated. Premafloxacin was equivalent to ciprofloxacin, enrofloxacin, and danofloxacin in activity against the gram-negative bacilli but was much more active (MIC for 90% of the strains tested [MIC90], 0.015 to 0.25 microg/ml) than the comparison antimicrobial agents (MIC90, 0.13 to 16.0 microg/ml) against the staphylococci, streptococci, and anaerobes tested.

Animals↗
PubMed1994

Effect of tumor necrosis factor-alpha, interleukin-1 beta, and antibiotics on the killing of intracellular Staphylococcus aureus.

A bovine blood polymorphonuclear neutrophil system was used to determine the ability of cytokines, alone or in combination with various antibiotics, to enhance the intracellular killing of Staphylococcus aureus sequestered within these phagocytes. Pretreatment of blood polymorphonuclear neutrophils with human recombinant tumor necrosis factor-alpha, bovine macrophage supernatant tumor necrosis factor-alpha, or human recombinant interleukin-1 beta enhanced the killing of S. aureus by the phagocytes compared with that of untreated polymorphonuclear neutrophils. This enhancement was dose-dependent and required 30 min of contact between the cytokine and the blood polymorphonuclear neutrophils. However, mammary gland polymorphonuclear neutrophils, macrophages, and blood monocytes showed no enhanced killing activity following pretreatment with tumor necrosis factor. Pretreatment of polymorphonuclear neutrophils with tumor necrosis factor and subsequent exposure to various antibiotics after infection with S. aureus enhanced intracellular bacterial killing by certain antibiotics, including paldimycin, rifampin, and ciprofloxacin (antibiotics that normally kill intracellular S. aureus). However, no enhancement occurred with antibiotics that do not normally kill intracellular S. aureus. Cytokine therapy may be a useful adjunct to antibiotic therapy in the treatment of bovine staphylococcal infection and mastitis.

Animals↗
PubMed1994

Efficacy of tumor necrosis factor-alpha and antibiotics in therapy of experimental murine staphylococcal mastitis.

The mouse model was used to determine the efficacy of the cytokine, tumor necrosis factor-alpha, and antibiotic in treatment of experimentally induced staphylococcal mastitis. Recombinant human tumor necrosis factor-alpha alone administered to the mammary glands of lactating mice recruited significantly more polymorphonuclear neutrophils into the gland by 4 h posttreatment than did the untreated control. One hundred times less recombinant mouse tumor necrosis factor-alpha than human tumor necrosis factor-alpha was required to enhance the killing of Staphylococcus aureus within the gland. Human tumor necrosis factor-alpha effectively enhanced the killing of the bacteria when it was administered 4 to 0 h prior to infection, but not 4 h after infection. When mice were first pretreated with tumor necrosis factor-alpha, infected, and then treated with antibiotics (ciprofloxacin and pirlimycin, but not cloxacillin), the combination of antibiotic and cytokine significantly reduced the number of bacteria within the gland compared with that for mice treated with antibiotic alone, cytokine alone, or placebo. Recombinant tumor necrosis factor-alpha may be an effective adjunct to antimicrobial therapy in treatment of staphylococcal mastitis in the bovine.

Animals↗
PubMed1991

Activity of antibiotics against Staphylococcus aureus within polymorphonuclear neutrophils.

The intracellular location of certain strains of Staphylococcus aureus serves as a reservoir of bacteria which is thought to be important in therapy of recurrent infections in humans and in chronic staphylococcal mastitis in dairy cows. This overview summarizes data pertaining to the intracellular survival of Staphylococcus aureus within polymorphonuclear neutrophils (PMNs) both in vitro and in vivo in the face of antibiotic treatment. While compounds such as rifampin, clindamycin, erythromycin, and ciprofloxacin have been shown to be rapidly taken up by PMNs, the ability of antibiotics to concentrate within PMNs did not strictly correlate with their ability to kill intracellular Staphylococcus aureus. Rifampin and ciprofloxacin have been shown to be the most effective intraphagocytic killing agents, while clindamycin and erythromycin were inactive in these in vitro assays. In vivo, in therapy of Staphylococcus aureus arthritis and peritonitis in humans and in certain mouse models rifampin has generally been shown to be more effective than comparator antibiotics. In a staphylococcal subcutaneous abscess model, however, clindamycin was very effective in curing the Staphylococcus aureus abscesses in this system where PMNs were the primary inflammatory cells involved. The intracellular bacterial counts decreased as rapidly as the extracellular bacteria. Rifampin was also effective in the abscess model but ciprofloxacin was ineffective at the highest doses tested. The relevance of in vitro and in vivo models and the importance of PMNs as a reservoir of infection in staphylococcal diseases in humans and the dairy cow are discussed.

Anti-Bacterial Agents↗
PubMed1990

[Prevalence of herpetic infection in a female Chilean population].

The prevalence of the herpes simplex virus infection was investigated in a chilean female population. During 1981 and 1985 a number of 1,003 women were analyzed through serological methods. A 29.1% of the group referred past history of oral herpes and 59.4% of these presented 1 to 2 recurrent episodes a year. The high prevalence of this infection in our population is shown when detecting that a 91.4% of the female population had antiherpes simplex antibodies and the titer of this antibodies were in direct correlation to the antecent of recurrent clinical herpes and to the frequency of these episodes.

Adolescent↗
PubMed1988

Evaluation of antibiotic effectiveness against Staphylococcus aureus surviving within the bovine mammary gland macrophage.

Bovine mastitis due to Staphylococcus aureus may become chronic and refractory to antibiotic therapy because of the organism's ability to survive within the mammary gland macrophages and/or polymorphonuclear neutrophils (PMNs). Therefore, phagocytosis and killing of S. aureus by bovine udder macrophages, udder and blood neutrophils and blood monocytes were studied. Gland and blood PMNs were about equally effective at phagocytosing (2.5 log reduction in supernatant) and killing the bacteria (92% reduction of viable bacteria by two hours). Gland macrophages phagocytosed at a lower rate (1.5 log reduction) and were less effective at killing the bacteria (73% reduction by two hours). Blood monocytes phagocytosed and killed S. aureus at the lowest rate. An udder macrophage monolayer system was developed and used to evaluate the ability of antibiotics to kill surviving intracellular S. aureus. This assay was similar to our previously described system with blood PMNs. Several classes of antibiotics were investigated. These included naphthalenic ansamycin, lincosaminide, tetracycline, coumarin, peptide, paulomycin, quinolone, macrolide, cephalosporin, and penicillin-class antibiotics. The activity of these compounds was compared to positive (rifampicin), negative (cloxacillin), and nonantibiotic treated controls. Only naphthalenic ansamycin class antibiotics, paulomycin, paldimycin and ciprofloxacin caused significant reduction in viable intracellular bacteria in the macrophage system. These results were similar to those obtained in the blood PMN monolayer system. Because a low intraphagolysosomal pH could affect an antibiotic's ability to kill intracellular bacteria by affecting the drug itself or inhibiting bacterial growth, the effect of low pH on the minimum inhibitory concentration and the minimum lethal concentration of clindamycin and rifampicin against three strains of S. aureus was also tested. While the activity of clindamycin at pH 5.0 compared to pH 7.0 was not affected greatly, the activity of rifampicin was greatly enhanced at acidic pH. These results suggest that at least some of the excellent activity of rifampicin for intracellular S. aureus is due to potentiation of its activity in the intracellular acidic compartment of the phagolysosome.

Animals↗
PubMed1986

Evaluation of antibacterial agents in a high-volume bovine polymorphonuclear neutrophil Staphylococcus aureus intracellular killing assay.

A bovine polymorphonuclear leukocyte (PMN) monolayer system was used to determine the ability of different antibiotics to kill surviving intracellular Staphylococcus aureus. The following classes of antimicrobial agents were tested in this high-volume assay procedure: aminocyclitol, beta-lactam, coumarin, lincosaminide, macrolide, naphthalenic ansamycin, paulomycin, peptide, quinolone, and tetracycline. The activities of these compounds were compared with those of positive (rifampin), negative (cloxacillin), and non-antibiotic-treated controls. Only oxytetracycline, the ansamycins (rifampin, rifamycin SV, streptovaricin A, C, and D), paulomycin, and paldimycin caused a significant reduction in the viable count of intracellular S. aureus. Of these, however, the intracellular killing by the streptovaricins was directly related to the cytotoxicity (as determined by trypan blue exclusion) of these compounds for the PMNs. Although the paulomycins were cytotoxic for the PMNs, the cytotoxic and the intracellular killing activity of these new compounds could be distinguished. The relevance of these results to the therapeutic effectiveness of these antibiotics in the treatment of bovine staphylococcal mastitis is discussed.

Animals↗