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Biomedical subjects

J Del Castillo

Publications and source records attributed to J Del Castillo.

At least 19 recordsLinked to original sources
PubMed2006

Sorption kinetics of chlortetracyline and tylosin on sandy loam and heavy clay soils.

Antibiotics may appear in the environment when manure, sewage sludge, and other organic amendments are added to soils. There is concern that the presence of antibiotics in soils may lead to the development of antibiotic-resistant bacteria which may spread to the rest of the environment. This paper aims at evaluating the sorption kinetics of two antibiotics frequently used in pig production. The results indicate that sorption of chlortetracycline (CTC) and tylosin (TYL) in sandy loam and clay occurs very fast. More than 95% of the CTC adsorption is completed within 10 min on both soils and of TYL within 3 h. These results suggest that 24-h soil and antibiotic solution mixtures is enough for sorption studies. Also, there is less likelihood that these antibiotics will leach through soil and appear in the ground water since their sorption on soils is very high unless they are carried by soil particles through preferential flow. There was also no effect of soil sterilization on sorption kinetics of these antibiotics thus suggesting that there is minimal probability of the antibiotics degrading by microorganisms during 24- to 48-h adsorption studies.

Adsorption↗
PubMed2001

Prolonged neutropenia in a novel mouse granulocyte colony-stimulating factor neutralizing auto-immunoglobulin G mouse model.

Therapeutic use of recombinant human cytokines in humans can result in the generation of drug-specific antibodies. To predetermine the maximum potential effects of a granulocyte colony-stimulating factor (G-CSF) neutralizing auto-immunoglobulin G (auto-IgG) response during recombinant human G-CSF therapy, we developed a mouse model of mouse G-CSF (mG-CSF) neutralizing auto-IgG response. Mice were immunized and boosted with mG-CSF chemically conjugated to either keyhole limpet hemocyanin or ovalbumin on an alternating schedule. Sera were analyzed for mG-CSF-specific titers and full blood counts were performed on a Technicon H-1E. On day 252, tissues were collected for histology. IgG was protein A affinity purified from pooled mG-CSF autoimmune sera. Mice immunized with mG-CSF conjugates produced mG-CSF-specific auto-IgG responses that lasted for the length of the study. Significant neutropenia (p(max) < 0.004) was concurrent with the rise in mG-CSF-specific IgG titers. However, neutrophil counts remained at approximately 20% of preimmunization levels through day 252. Endogenous mG-CSF neutralizing auto-IgG had no significant effect on hemoglobin, erythrocyte, lymphocyte, eosinophil, basophil, and platelet counts, and had minor, transient, or no effects on monocyte counts. Bone marrow colony assays from mG-CSF autoimmune mice demonstrated no significant effect of G-CSF neutralization on the numbers or proliferative capacity of preneutrophil lineage progenitors. Purified IgG from mG-CSF autoimmune mice neutralized mG-CSF in vitro. High-titer G-CSF neutralizing auto-IgG in adult mice partially inhibited steady-state granulopoiesis and had little or no effect on steady-state levels of other hematopoietic cells.

Animals↗
PubMed2001

Novel erythropoiesis stimulating protein (darbepoetin alfa) alleviates anemia associated with chronic inflammatory disease in a rodent model.

OBJECTIVE: We developed a rodent model of noninfectious systemic inflammation to examine the pathogenesis of the associated anemia of chronic disorders (ACD), to evaluate the similarity of this ACD model to human ACD, and to evaluate the potential efficacy of novel erythropoiesis stimulating protein (darbepoetin alfa) as an ACD therapy. METHODS: Lewis rats were immunized with peptidoglycan-polysaccharide polymers (PG-APS), the chronic inflammation and associated ACD were characterized, and the effects of darbepoetin alfa treatment on complete blood counts (CBC), red blood cell (RBC) indices, and iron metabolism were analyzed weekly. RESULTS: Acutely inflamed rats had reduced peripheral blood (PB) RBC counts and hemoglobin (Hb) concentrations and increased reticulocyte counts. PB RBC numbers normalized during chronic inflammation, but RBC remained hypochromic and microcytic. Consequently, the rats remained chronically anemic. Anemic rats had fluctuating serum erythropoietin (EPO) concentrations, but mean EPO concentrations never varied significantly from baseline control levels. Histology of anemic rat spleen sections revealed reticuloendothelial siderosis. Total serum iron concentrations were chronically low. Peritoneal exudate cells (PEC) isolated from anemic rats and stimulated with PG-APS in vitro produced more interleukin (IL)-1alpha and interferon (IFN)-gamma, and significantly more tumor necrosis factor (TNF)-alpha and IL-10 than control cultures. Darbepoetin alfa restored Hb concentrations to baseline levels within 2 to 7 weeks, depending on dosage. A refined treatment strategy restored Hb to baseline and maintained those levels with reduced dosing. CONCLUSION: ACD in this rodent model closely replicates human ACD. Darbepoetin alfa treatment reversed ACD in this model by increasing RBC production and RBC hemoglobinization while reducing siderosis and hypoferremia.

Anemia↗
PubMed1995

Catch in the primary spines of the sea urchin Eucidaris tribuloides: a brief review and a new interpretation.

Previous models of reversible catch in echinoid spines, as a property of muscle or of collagen, are briefly reviewed and discussed. This brief review offers a new interpretation of catch in primary spines of Eucidaris tribuloides, viewing the collagen and small muscles of the catch ligament working together as a variable-length tendon. In the model presented, changes in ligament length when out of catch are accommodated by sliding of discontinuous, interdigitating and cross-link-stabilized columns of collagen fibrils, the muscle layer external to the ligament effecting spine movement. Catch is viewed as a consequence of contraction of small muscles inserted on the collagen columns within the ligament. Ligament shortening tightens the profuse (ca. 30,000/mm2) and highly ordered collagen insertion loops within the stereoms of the spine base and test, and catch results from the multiplicative effect of these friction sites in series. New data are presented on novel structural cross-links between collagen fibrils. The cross-links stabilize the ligament columns. The central ligament in Eucidaris plays a purely passive mechanical role in maintaining the alignment of the spine-test articulation. It contains no muscle and neither contracts nor undergoes catch; its insertions are simple, unlike the complex stereom insertions of the main ligament.

Animals↗
PubMed1994

Intratracheal injection of LPS and cytokines. V. LPS induces expression of LIF and LIF inhibits acute inflammation.

Lipopolysaccharide (LPS) injected into the trachea of rats was found to induce the secretion of leukemia inhibitory factor (LIF) into bronchoalveolar lavage (BAL) fluid with a maximum expression of LIF after 2-12 h. The acute pulmonary neutrophilic inflammation caused by the intratracheal injection of bacterial endotoxin (LPS) could be inhibited by the intratracheal coinjection of recombinant LIF. Compared with intratracheal injection of LPS alone, intratracheal coinjection of LIF and LPS decreases the number of BAL neutrophils obtained 6 h later by approximately 50% (P < 0.0001). LIF decreased the amount of the proinflammatory cytokine tumor necrosis factor (TNF), but not the amount of the anti-inflammatory cytokine interleukin (IL)-6, in the BAL fluid of LPS-injected rats. Similarly, intravenous LIF was found to decrease TNF expression, but increase IL-6 expression, in the serum of rats receiving intravenous LPS. Intravenous LIF, even in the absence of LPS, was found to cause IL-6 expression. In conclusion, intratracheal LPS initiates the secretion of endogenous LIF into the alveolar space where LIF may contribute to the downregulation of LPS-initiated acute neutrophilic inflammation by downregulating expression of TNF. LIF may down-regulate LPS-initiated TNF expression at least in part indirectly by upregulating expression of IL-6, a cytokine known to downregulate LPS-initiated TNF expression.

Acute Disease↗
PubMed1993

[The use of monoclonal antibodies in the study of ion transporting pumps].

The active ion transport is related to some vital functions for the normal eukaryotic cell metabolism. The study of transport mechanism and its regulation is a fundamental problem in cellular biology. The production of monoclonal antibodies (AcM) let us to have a probe, with large specificity, for the study of the localization, distribution and function of carrier proteins in the epithelium, as well as the study of its molecular structure, synthesis and assembling in the cell. The quality of a monoclonal antibody depends of the proper selection of each step to follow in the course of its production. In this article, we examine the strategy more currently used in the production of monoclonal antibodies and its direct use in the ionics pump's morphological, biochemical and physiological study.

Animals↗
PubMed1990

The attachment of collagenous ligament to stereom in primary spines of the sea-urchin, Eucidaris tribuloides.

The similar proximal and distal attachments to the stereom of primary spine ligament in the echinoid Eucidaris tribuloides are described, from thin sections and SEM studies on frozen and fractured spine articulations and ligaments from decalcified material. The orthogonal structure of the general stereom is modified on the attachment zones where bundles of collagen cylinders enter approximately hexagonally arranged channels. Straps of collagen extend in parallel series between adjacent bundles via regularly placed ports and collagen loops rather than non-striated 'tendons' pass over skeletal trabeculae. The regular pattern of collagen straps is most evident on the proximal and distal attachment zones. Mechanical features of the non-adhesive mode of attachment are considered, together with similarities and differences between insertion of muscle cells and mutable collagenous tissue (ligament) in echinoderms.

Animals↗
PubMed1977

Rapid desensitization of acetylcholine receptors of eel electroplaques following iontophoretic application of agonist compounds.

1. The electrical potential difference across the innervated membrane of the electroplaque of Electrophorus electricus was measured with an intracellular micro-electrode while an extracellular double-barrelled micropipette was used to apply acetylcholine and carbamylcholine iontophoretically very close to the point of insertion of the recording electrode. 2. The average depolarizing response to brief (several msec) pulses of carbamylcholine decayed 22 times more slowly than the response to acetylcholine. Treatment of the electroplaque with eserine or neostigmine prolonged the acetylcholine responses. 3. When a steady current of acetylcholine was applied for several seconds, the membrane first depolarized, then partially repolarized. Usually no repolarization was seen during long pulses of carbamylcholine or long pulses of acetylcholine in the presence of eserine or neostigmine. 4. During long conditioning pulses of acetylcholine or carbamylcholine, the responses to brief test pulses of acetylcholine showed a progressive decline in amplitude, but recovered after termination of the conditioning pulse. Desensitization half-times as short as 0-6 sec were observed, making these results similar to those obtained in the frog motor end-plate.

Acetylcholine↗