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J C Sánchez

Publications and source records attributed to J C Sánchez.

At least 19 recordsLinked to original sources
PubMed2003

Effects of hypotonic shock on intracellular pH in bovine articular chondrocytes.

Chondrocytes inhabit an unusual environment, in which they are repeatedly subjected to osmotic challenges as fluid is expressed from the extracellular matrix during static joint loading. In the present study, the effects of hypotonic shock on intracellular pH, pH(i), have been studied in isolated bovine articular chondrocytes using the pH-sensitive fluroprobe BCECF. Cells subjected to a 50% dilution rapidly alkalinised, by approximately 0.2 pH units, a sustained plateau being achieved within 300 s. The effect was not altered by inhibitors of pH regulators, such as amiloride, bafilomycin and SITS, but was absent when cells were subjected to hypotonic shocks in solutions in which Na(+) ions were replaced by NMDG(+). The response was found to be sensitive to Gd(3+) ions, blockers of stretch-activated cation channels. Alkalinisation was also inhibited by treatment with Zn(2+) ions, at a concentration reported to block voltage-activated H(+) channels (VAHC). Depolarisation using high K(+) solutions supplemented with valinomycin also induced intracellular alkalinisation. Measurements using a membrane potential (E(m)) fluorescent dye showed that E(m) was approximately -44 mV, but was depolarised by over 50 mV following HTS. The depolarisation was also inhibited by Na(+) substitution with NMDG(+) or treatment with Gd(3+). We conclude that in response to HTS the opening of a stretch-activated cation channel leads to Na(+) influx, which results in a membrane depolarisation. Subsequent activation of VAHC permits H(+) ion efflux along the prevailing electrochemcial gradient, leading to the alkalinisation, which we record.

Alkalies↗
PubMed2003

Mechanisms involved in the increase in intracellular calcium following hypotonic shock in bovine articular chondrocytes.

The extracellular osmotic environment of chondrocytes fluctuates during joint loading as fluid is expressed from and reimbibed by the extracellular matrix. Matrix synthesis by chondrocytes is modulated by joint loading, possibly mediated by variations in intracellular composition. The present study has employed the Ca2+-sensitive fluoroprobe Fura-2 to determine the effects of hypotonic shock (HTS) on intracellular Ca2+ concentration ([Ca2+]i) and to characterise the mechanisms involved in the response for isolated bovine articular chondrocytes. In cells subjected to a 50% dilution, [Ca2+]i rapidly increased by approximately 250%, a sustained plateau being achieved within 300 s. The effect was inhibited by thapsigargin or by removal of extracellular Ca2+, indicating that the rise in [Ca2+]i reflects both influx from the extracellular medium and release from intracellular stores. Inhibition of the response by neomycin implicates activation of PLC and IP3 synthesis in the mobilisation of Ca2+ from intracellular stores. The rise was insensitive to inhibitors of L-type voltage-activated Ca2+ channels (LVACC) or reverse mode Na+/Ca2+ exchange (NCE) but could be significantly attenuated by ruthenium red, an inhibitor of transient receptor potential vanilloid (TRPV) channels and by Gd3+, a blocker of stretch-activated cation (SAC) channels. The HTS-induced rise in [Ca2+]i was almost completely absent in cells treated with Ni2+, a non-specific inhibitor of Ca2+ entry pathways. We conclude that in response to HTS the opening of SACC and a member of TRPV channel family leads to Ca2+ influx, simultaneously with the release from intracellular stores.

Adaptation, Physiological↗
PubMed2002

Secretion of human interferon alpha 2b by Streptomyces lividans.

Biologically active human interferon alpha 2b (HuIFNalpha-2b) was secreted into the culture medium by Streptomyces lividans transformed with recombinant plasmids coding for HuIFNalpha-2b fused to the Streptomyces exfoliatus M11 lipase A signal sequence. Levels were low, 15 or 100 ng/ml, depending on the plasmid used. Neither processed nor unprocessed HuIFNalpha-2b was detected in cell lysates of the transformants secreting the recombinant product. However, the secreted recombinant product was found to partially degrade when cultures reached the stationary phase by the action of an, as yet, unidentified mycelium-associated factor. Experimental evidence suggests that the degrading factor is related to mycelium-associated proteolytic activity.

Culture Media↗
PubMed2002

[Cardiorespiratory arrest: a rare complication of subdural block].

We report a case of accidental subdural block after epidural anesthesia that manifested as cardiac arrest due to extensive spinal blockade 20 minutes after administration of 50 mg of 0.5% bupivacaine. The event resolved without sequelae. Subdural placement of the catheter was verified by computed axial tomography contrast medium. Clinical signs of subdural block are highly variable, extensive neural block being among the possible rare presentations, with latency ranging from a few minutes to as long as 30. Recent electron microscope observations with new methods for fixing and preparing tissues suggest that the dubdural space does not exist naturally, but rather forms artificially within a low-resistance cell plane composed of neurothelial cells, as a result of trauma or the injection of a local anesthetic. The characteristics of the space depend, therefore, on factors that come together at the site. These data explain the great variability in the clinical manifestations of a subdural block. The case of cardiopulmonary arrest we report is rare in the literature.

Aged↗
PubMed1997

Action of ebrotidine, ranitidine and cimetidine on the specific binding to histamine H1- and H2-receptors.

Ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)-4-thiazolyl]methyl]thio] ethyl]amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542), a selective H2-receptor antagonist, has proved to competitively inhibit the positive chronotropism induced by histamine in isolated guinea pig atrium. The affinity of ebrotidine to histamine H1- and H2-receptors through the displacement of 3H-pyrilamine and 3H-thiotidine binding to guinea pig cerebellum and brain cortex membranes was investigated. Ebrotidine displaced 3H-thiotidine specific binding to histamine H2-receptors (Ki: 127.5 nmol/l), showing a higher affinity (p < 0.05) than ranitidine (Ki: 190.0 nmol/l) and cimetidine (Ki: 246.1 nmol/l). None of the three substances displaced 3H-pyrilamine binding to H1-receptors (Ki: > 5000 nmol/l). The results showed that ebrotidine is a drug with a high affinity for H2 receptors, higher than cimetidine and ranitidine.

Animals↗
PubMed1994

Activation of a cryptic gene encoding a kinase for L-xylulose opens a new pathway for the utilization of L-lyxose by Escherichia coli.

A silent gene encoding a kinase that specifically phosphorylates L-xylulose was activated and rendered constitutive in mutant cells of Escherichia coli. L-Xylulose kinase was purified to homogeneity and found to be a dimer of two subunits of 55 kDa, highly specific for L-xylulose with a Km of 0.8 mM, a Vmax of 33 mumol/min/mg, and an optimum pH of 8.4. Physical (thin layer chromatography) and spectroscopic (nuclear magnetic resonance and optical rotation) characterization of the product of L-xylulose kinase indicated that the enzyme phosphorylated the sugar at position 5. The gene encoding L-xylulose kinase was mapped in the 80.2 min region of the chromosome by conjugation and transduction. Cloning and comparison of the restriction map with the Kohara map (Kohara, Y., Akiyame, K., and Isono, K. (1987) Cell 50, 495-501) located the gene between positions 3963 and 3965 kilobases. The molecular and functional features of L-xylulose kinase together with the location of the corresponding gene indicate that this enzyme did not derive from mutation of any other known kinase. The new kinase opens a route for the utilization of L-lyxose through the action of rhamnose permease, rhamnose isomerase, and the phosphorylation of the L-xylulose formed to L-xylulose 5-phosphate, which is then introduced into the pentose phosphate pathway for subsequent metabolism.

Cloning, Molecular↗
PubMed1991

[Evaluation of 2 serological techniques in the diagnosis of neurocysticercosis: complement fixation reaction and Western blot].

Evaluation of two serological techniques for diagnosis cysticercosis: complement fixation reaction and Western blot. Comparative study that includes 49 sera samples and 30 CSF samples belonging to 35 patients with clinical diagnosis of cysticercosis of the CNS. As a control group we used 10 sera samples of patients with Trichinella spiralis infection, 33 sera samples of patients with hydatid cyst disease, 9 sera samples from patients with oxyuriasis, 52 sera samples of healthy blood donors and 22 additional CSF samples from patients with different CNS disorders. Thirty-one samples were positive by Western blot technique and 21 samples by complement fixation reaction technique. Agreement between both techniques was 76%. Gathering clinical and laboratory information we believe that a total of 11 patients had cysticercosis of the CNS (33 samples), and three additional patients remain with indeterminate diagnosis. We have also detected cross-reactions with Western blot techniques (reactivity to more than one band) in 43% of patients with hydatid disease and in 20% of patients with Trichinella spiralis infection, but none in oxyuriasis patients. The CFR technique had cross-reaction with 33% of sera samples from hydatid disease patients and 20% of those from oxyuriasis patients. No cross-reactions were seen in any of control patients with both techniques. The two different techniques tested can be of help, together with clinical and radiology data, in the diagnosis of cysticercosis of the CNS. However, both techniques showed strong cross-reactions with hydatid disease.

Animals↗
PubMed1989

[Brucellosis and acute inflammatory polyradiculoneuropathy].

Three patients with Guillain-Barré syndrome (GBS) during active brucellosis are reported: in one of them, who had an unfavorable outcome, the clinical features, the neurophysiological studies and the sural nerve biopsy were consistent with the axonal form of GBS. In the remaining two patients, who had a satisfactory course, the neurophysiological studies and the sural nerve biopsy disclosed the demyelinating character of the disease. We agree with other authors that the axonal and demyelinating forms of GBS should be separated, in view of their different clinical and possibly pathogenetic implications, both in GBS in general and in the form associated with brucellosis.

Adult↗