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Biomedical subjects

A Sanchez

Publications and source records attributed to A Sanchez.

At least 163 records · Page 9Linked to original sources

Histological response of Eptesicus serotinus (Mammalia: Chiroptera) to Argas vespertilionis (Acari: argasidae).

The sequential histological development of Argas vespertilionis (Acarina: Argasidae) feeding sites on Eptesicus serotinus (Mammalia: Chiroptera) was evaluated. Neutrophils, followed by Langerhans cells, were the major components of the cellular infiltrate throughout the earliest phase of tick infestation. The host tended to isolate the tick mouthparts by means of a progressive formation of epithelial tissue in the feeding cavity.

Adenosine Triphosphatases↗

The effect of three commercially available dentifrices containing triclosan on supragingival plaque formation and gingivitis: a six month clinical study.

In order to compare the antiplaque and antigingivitis activity of three commercially-available triclosan containing dentifrices with that of a placebo dentifrice without triclosan, a double-blind clinical study was conducted on 194 subjects over six months. Following baseline supragingival plaque and gingivitis examinations and a complete oral prophylaxis, subjects were stratified by their whole mouth baseline plaque (modified Quigley-Hein) and gingivitis (modified Löe-Silness) scores and then randomly assigned to one of four dentifrice using groups. Plaque and gingivitis examinations were then performed after six weeks, three months and six months use of the dentifrices. Subjects brushed twice daily in their customary manner. The triclosan/soluble pyrophosphate and the triclosan/zinc citrate commercially available dentifrices did not provide statistically significant reductions in either supragingival plaque accumulation or gingivitis at any of the examination intervals, as compared to the placebo dentifrice. The subjects using the commercially available triclosan/copolymer dentifrice had, after six months, statistically significant reductions in supragingival plaque (11.3 per cent), plaque severity (18.8 per cent), gingivitis (19.9 per cent) and gingivitis severity (27.8 per cent), as compared to the placebo dentifrice.

Adolescent↗

Transependymal diapedesis: reality or speculation?

The present study attempts to describe the possible origin of certain elements situated inside the infundibular recess of the third ventricle, such as supraependymal cells and Herring bodies, together with the way in which they reach the ventricular lumen. We used albino Sprague-Dawley rats and cats of both sexes sacrificed at different ages. The results point to the possible existence of a transependymal diapedesis of some Herring bodies and supraependymal cells into the infundibular recess.

Animals↗

Priming for the synthesis of 5-lipoxygenase products in human blood ex vivo by human granulocyte-macrophage colony-stimulating factor and tumor necrosis factor-alpha.

BACKGROUND: Previous studies reported the priming effects of granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor-alpha (TNF alpha) on leukotriene synthesis by isolated polymorphonuclear leukocytes; however, little is known as of yet of these biologic effects of the two cytokines in a physiologic environment. EXPERIMENTAL DESIGN: In this study, we investigate the effects of GM-CSF and TNF alpha on the synthesis of 5-lipoxygenase (5-LO) products in heparinized blood stimulated ex vivo, using reverse phase high performance liquid chromatography analysis of deproteinized plasma samples. RESULTS: Stimulation of blood with f-Met-Leu-Phe resulted in the accumulation of up to 30 pmol of 5-LO products/ml of plasma. Preincubation of blood with 100 pM GM-CSF or 1.2 nM (200 units/ml) TNF alpha for 30 minutes at 37 degrees C before stimulation with f-Met-Leu-Phe resulted in a marked enhancement (> 5-fold) of the synthesis of leukotriene B4 and 5(S)-hydroxyeicosatetraenoic acid, which were formed in equivalent amounts. GM-CSF and TNF alpha priming activities were detectable at concentrations as low as 3 pM and 6 pM (1 unit/ml), respectively. The preincubation times required for optimal priming by GM-CSF and TNF alpha were different (40 and 10 minutes, respectively), and the effects of the two cytokines on leukotriene B4 and 5(S)-hydroxyeicosatetraenoic acid synthesis were additive, suggesting different priming mechanisms. The synthesis of 5-LO products in primed blood was also induced by platelet-activating factor, the complement fragment C5a, the particulate stimulus zymosan, and the ionophore A23187, but not by interleukin-8. Polymorphonuclear leukocytes and mononuclear cells accounted for 80% and 20% of the synthesis of 5-LO products, respectively. CONCLUSIONS: These data demonstrate that GM-CSF and TNF alpha exert very potent priming effects on the biosynthesis of 5-LO products in whole blood stimulated by various stimuli and strongly support that these cytokines could be important modulators of lipid mediator synthesis in physiologic and pathophysiologic conditions.

Arachidonate 5-Lipoxygenase↗

Genetic identification of a hantavirus associated with an outbreak of acute respiratory illness.

A mysterious respiratory illness with high mortality was recently reported in the southwestern United States. Serologic studies implicated the hantaviruses, rodent-borne RNA viruses usually associated elsewhere in the world with hemorrhagic fever with renal syndrome. A genetic detection assay amplified hantavirus-specific DNA fragments from RNA extracted from the tissues of patients and deer mice (Peromyscus maniculatus) caught at or near patient residences. Nucleotide sequence analysis revealed the associated virus to be a new hantavirus and provided a direct genetic link between infection in patients and rodents.

Animals↗

Control of Ca2+ entry into HL60 and U937 human leukaemia cells by the filling state of the intracellular Ca2+ stores.

Differentiation of HL60 cells by treatment with dimethyl sulphoxide induces the expression of membrane receptors for N-formylmethionyl-leucyl-phenylalanine (fMLP) and for platelet-activating factor (PAF). In these cells both agonists produced an increase in the cytosolic Ca2+ concentration ([Ca2+]i) by release of Ca2+ from the intracellular stores, followed shortly by an acceleration of the entry of Ca2+ or Mn2+, used here as a Ca2+ surrogate for Ca2+ channels. Cytochrome P-450 inhibitors blocked the agonist-induced entry of Ca2+ or Mn2+ with no modification of Ca2+ release from the stores. Emptying the intracellular Ca2+ stores either by treatments inducing no inositol phosphate production, such as prolonged incubation in Ca(2+)-free medium or treatment with the Ca2+ ionophore ionomycin, increased the plasma-membrane permeability to Ca2+ and Mn2+. This Ca(2+)-store-regulated Mn2+ entry was inhibited by Ni2+ and by cytochrome P-450 inhibitors. Refilling of the Ca2+ stores by incubation in Ca(2+)-containing medium restored low Mn2+ permeability. The same mechanism is present and functional in non-differentiated cells, before expression of membrane receptors for fMLP and PAF. These results suggest that agonist-induced Ca2+ (Mn2+) entry is secondary to the emptying of the intracellular Ca2+ stores, which in turn activates plasma-membrane channels by a mechanism involving cytochrome P-450.

Antifungal Agents↗

Molecular biology and evolution of filoviruses.

The family Filoviridae contains extremely pathogenic human viruses causing a fulminating, febrile hemorrhagic disease. Filoviruses are enveloped, filamentous particles with a nonsegmented negative-strand RNA genome showing the gene arrangement 3'-NP-VP35-VP40-GP-VP30-VP24-L-5'. Genes are flanked by highly conserved transcriptional signals and are generally separated by variable intergenic regions. They are transcribed into monocistronic polyadenylated messenger RNAs which contain relatively long 5' and 3' untranslated regions. Seven structural proteins are encoded by the genome of which four form the helical nucleocapsid (NP-VP35-VP30-L), two are membrane-associated (VP40-VP24), and one is a transmembrane glycoprotein (GP). Comparison of filovirus genomes with those of other nonsegmented negative-strand RNA viruses suggest comparable mechanisms of transcription and replication and a common evolutionary lineage for all these viruses. Sequence analyses of single genes, however, showed that filoviruses are more closely related to paramyxoviruses, particularly human respiratory syncytial virus. These data support the concept of the taxonomic order Mononegavirales for all nonsegmented negative-strand RNA viruses and the classification of Marburg virus, Ebola virus, and Reston virus in the family Filoviridae, separate from the families Paramyxoviridae and Rhabdoviridae.

Animals↗

The pathway for refilling intracellular Ca2+ stores passes through the cytosol in human leukaemia cells.

The pathway for refilling the intracellular Ca2+ stores of HL60 and U937 human leukaemia cells loaded with fura-2 has been investigated. On addition of external Ca2+ to cells with empty stores there was an increase in the cytosolic Ca2+ concentration ([Ca2+]i) which preceded the refilling of the stores. The increase in [Ca2+]i was faster than the refilling, by 3- to 15-fold, depending on the cell type. In measurements in single HL60 cells we found that the refilling of the stores correlated with the extent of the [Ca2+]i increase on addition of external Ca2+. The cells showing no [Ca2+]i increase were unable to refill their stores. The addition of Ni2+ to the extracellular medium prevented both the [Ca2+]i increase and the refilling of the stores. These results indicate that the limiting step for store refilling is the entry of Ca2+ from the extracellular medium to the cytosol. Hence, we conclude that extracellular Ca2+ cannot gain access directly to the intracellular Ca2+ stores in these cells, but must first enter the cytosol and be taken up from there into the stores.

Calcium↗

Ebola protein analyses for the determination of genetic organization.

Amino-acid sequencing of the purified major nucleoprotein (NP), VP35 and VP40 from purified Ebola virus proved that they are the protein products of the first three genes, and that the open reading frame (ORF) of the NP begins at nucleotide 470. Because of the many unusual features of the ORFs of Ebola virus, we thought that our conclusions should be substantiated. Comparisons of in vitro-translation products to purified viral proteins were used to demonstrate conclusively that the NP, VP35 and VP40 were the protein products of genes one, two, and three, respectively. Studies using antibodies to synthetic peptides matching the N- and C-termini of the deduced sequences from these genes confirmed these conclusions and that the ORF for the NP begins at nucleotide 470. Subsequent studies confirmed that VP30 is encoded by the fifth gene.

Amino Acid Sequence↗

Hydrosyringomyelia-Chiari I complex. Prospective evaluation of a modified foramen magnum decompression procedure: preliminary results.

A modified foramen magnum decompression procedure, designed to respect the subarachnoid spaces as much as possible, was prospectively evaluated in eight consecutive patients with a progressive clinical syndrome related to hydrosyringomyelia-Chiari I complex. This evaluation included quantitative clinical and magnetic resonance follow-up of at least 1 year in the first six patients and 6 months for the last two. Magnetic resonance scans at 6 months or more confirmed a persistent reduction of the hydrosyringomyelic cavity in all cases, which was associated with obvious subjective improvement. All patients have maintained this improvement. The operative technique and methods of clinical and radiological follow-up are discussed.

Adolescent↗

Sequence analysis of the Ebola virus genome: organization, genetic elements, and comparison with the genome of Marburg virus.

Sequence analysis of the second through the sixth genes of the Ebola virus (EBO) genome indicates that it is organized similarly to rhabdoviruses and paramyxoviruses and is virtually the same as Marburg virus (MBG). In vitro translation experiments and predicted amino acid sequence comparisons showed that the order of the EBO genes is: 3'-NP-VP35-VP40-GP-VP30-VP24-L. The transcriptional start and stop (polyadenylation) signals are conserved and all contain the sequence 3'-UAAUU. Three base intergenic sequences are present between the NP and VP35 genes (3'-GAU) and VP40 and GP genes (3'-AGC), and a large intergenic sequence of 142 bases separates the VP30 and VP24 genes. Novel gene overlaps were found between the VP35 and VP40, the GP and VP30, and the VP24 and L genes. Overlaps are 20 or 18 bases in length and are limited to the conserved sequences determined for the transcriptional signals. Stem-and-loop structures were identified in the putative (+) leader RNA and at the 5' end of each mRNA. Hybridization studies showed that a small second mRNA is transcribed from the glycoprotein gene, and is produced by termination of transcription at an atypical polyadenylation signal located in the middle of the coding region. The predicted amino acid sequence of the glycoprotein contains an N-terminal signal peptide sequence, a hydrophobic anchor sequence, and 17 potential N-linked glycosylation sites. Alignment of predicted amino acid sequences showed that the structural proteins of EBO and MBG contain large regions of homology despite the absence of serologic cross-reactivity.

Amino Acid Sequence↗

Utilization of autopsy RNA for the synthesis of the nucleocapsid antigen of a newly recognized virus associated with hantavirus pulmonary syndrome.

A newly recognized hantavirus was recently found to be associated with an outbreak of acute respiratory illness in the southwestern United States. The disease, which has become known as hantavirus pulmonary syndrome, has an unusually high mortality (64%). Virus isolation attempts have been unsuccessful thus far, resulting in a lack of homologous antigen for use in diagnostic assays. For this reason, a molecular approach was initiated to produce recombinant homologous antigen. The virus nucleocapsid (N) protein was selected, since N has been shown to be a sensitive antigenic target in other hantavirus systems. The N protein open reading frame of the virus S genome segment was synthesized from frozen autopsy tissue by polymerase chain reaction amplification, followed by cloning and expression in Hela cells (vaccinia-T7 RNA polymerase system) and Escherichia coli. N protein-expressing Hela cells served as excellent antigens for an improved indirect immunofluorescence assay. Use of the E. coli-expressed N protein in an enzyme-linked immunosorbent assay improved the sensitivity and specificity when compared with heterologous antigens used previously. Preliminary analysis also indicates that the higher sensitivity could result in earlier detection of infected persons. These data demonstrate that even in the absence of a virus isolate, the necessary homologous antigen can be produced and can serve to improve the detection and diagnostic capabilities needed to combat this newly recognized fatal respiratory illness in the United States.

Amino Acid Sequence↗

Iron deficiency anemia after successful renal transplantation.

In patients with chronic renal failure, renal transplantation improves anemia and the production of erythropoietin. In patients undergoing hemodialysis the administration of recombinant human erythropoietin improves anemia with a decrease in bodily iron stores. Therefore, one would expect a similar decrease after kidney transplantation. We followed the ferric parameters to determine the incidence of iron deficiency anemia in 24 consecutive renal transplant patients for an interval long enough to achieve steady state values of hemoglobin (5.1 +/- 0.8 months). Hematological parameters and serum levels of iron, ferritin and erythropoietin were measured. The patients were divided into 2 groups according to the decrease in serum ferritin: group 1--16 with a decrease in respect to basal values (114 +/- 56 ng./ml.) and group 2--those without modifications (720 +/- 320 ng./ml.). Except for the similar values, group 1 showed greater improvement in anemia (red blood cells 4.3 x 10(6) +/- 1.1 x 10(6) versus 3.7 x 10(6) +/- 1.5 x 10(6)/ml., p < 0.01) and hematocrit index (38.5 +/- 5.2 versus 33.0 +/- 5.1%, p < 0.05). Four patients had microcythemia (mean corpuscular volume 76.6 +/- 1.4 fluid) with lower hemoglobin values than the other patients in group 1 (10.77 +/- 0.42 versus 12.79 +/- 0.42 gm./dl., p < 0.05). Among the 16 patients in group 1, 7 of 8 whose basal serum ferritin was less than 150 ng./ml. achieved ferritin levels of less than 30 ng./ml. In conclusion, our data support that renal transplantation produces a rapid decrease in iron stores and in some cases induces iron deficiency anemia. This fact should be evaluated and treated properly.

Adult↗

Baseline entomological data for a pilot malaria control program in Equatorial Guinea.

Entomological studies conducted on the island of Bioko and the mainland province, Río Muni, in Equatorial Guinea provided baseline data for a pilot malaria control program. The main species collected resting in houses at low density were Anopheles gambiae s.l. Giles and Anopheles funestus Giles. An. gambiae s.l. density increased during the rainy season, whereas An. funestus populations remained stable during both dry and wet seasons. Both species tended to be endophilic and were not collected resting or biting outdoors. Overall, delayed sporozoite rates were about 10% for both species and were highest in the dry season. An. gambiae s.l. from the mainland showed resistance to 4% DDT, but the island population was still susceptible. All populations were completely susceptible to 5% malathion and 0.025% deltamethrin.

Animals↗

Antibiotic susceptibility of group A streptococci: a 6-year follow-up study.

The susceptibility patterns of group A streptococci over the last 6 years in our hospital were determined. Since our last study, carried out in 1987, all isolates have remained very susceptible in vitro to penicillin and all of the other beta-lactam agents tested. We observed resistance to erythromycin, clindamycin, tetracycline, and ofloxacin. The prevalence of erythromycin-resistant group A streptococci did not change appreciably throughout the study period.

Anti-Bacterial Agents↗

Podoconiosis in the Ethiopian Rift Valley. Role of beryllium and zirconium.

A geogenic origin has been proposed in the aetiology of non-filarial elephantiasis of the feet and legs, recently renamed podoconiosis. Soil collected in an area of the Ethiopian Rift Valley, the borough of Ocholo, known for its high prevalence of podoconiosis (5.06%), has been submitted to mineral analysis. High values of sulphur (S), cerium (Ce), lanthanum (La) and neodymium (Nd), typical for basaltic bedrocks, were found. Of special interest were the values for zirconium (Zr) and beryllium (Be), 618 +/- 87 ppm and 4.6 +/- 0.5 ppm respectively, twice as high as those recorded for soils sampled in neighbouring areas where the prevalence of podoconiosis is low. To be noted also, a high content in vanadium, above 250 ppm, in half of the soil samples collected in this region. Year-long exposure of unprotected feet to Zr and Be, known for their ability to induce granuloma formation in the lymphoid tissue of man, and present in a clay rich in colloidal silica particle, highly abrasive to skin, is doubtlessly a factor involved in the development of lymph node sclerosis leading to elephantiasis.

Adolescent↗