Search PubMed⌕ Search

Biomedical subjects

F J Castillo

Publications and source records attributed to F J Castillo.

At least 37 records · Page 2Linked to original sources
PubMed1998

[Quinolone resistance in Salmonella enterica].

Nalidixic acid resistance is a marker of quinolone sensibility in Salmonella spp. In our laboratory we observed an increase of nalidixic acid resistant strains from 0.44% in 1990 to 13.7% in 1996. The purpose of this work was to study the evolution of nalidixic acid resistance in Salmonella spp., as well as the association with certain serotypes and the cross-resistance to others agents. A total of 1,782 isolates of Salmonella enterica were studied from fecal and blood sources over a 7-year period; 45 strains (2.52%) were resistant to nalidixic acid (MIC > 16 microgram/ml). Two isolates required 2 microgram/ml of ciprofloxacin for inhibition, while the remaining 43 strains required 1 microgram/ml. The most frequent serotypes in nalidixic acid resistant strains were the following: enteritidis (33.3%), hadar (31.11%) and virchow (15.5%). In 1996, enteritidis was the predominant serotype (13/31), and hadar serotype was found to have the greatest nalidixic acid resistance at 80% of strains. No differences of sensibility to other agents were detected between the nalidixic acid resistant group and nalidixic acid sensitive strains. This type of resistance appears regularly in uncommon serotypes such as hadar. The increasing incidence of resistant isolates in enteritidis in 1996 is of even greater concern.

Anti-Infective Agents↗
PubMed1997

Diplogonoporiasis presumably introduced into Spain: first confirmed case of human infection acquired outside the Far East.

A 58-year-old man who was very fond of eating raw fish and had not left Zaragoza Province in Spain in the last 20 years excreted a short chain of gravid proglottids. Treatment with 50 mg/kg of paromomycin sulfate was divided into three doses, all given within the same day, followed by administration of a laxative at night. On days 1 and 2 post-treatment, several chains of degenerated proglottids were evacuated. Only eggs were expelled on days 3 and 4. A long complete strobila including the scolex, and immature, mature, and gravid segments was spontaneously discharged on day 25 after treatment. It was identified as Diplogonoporus balaenopterae, and was the first confirmed case of diplogonoporiasis outside the Far East (all previous cases were reported from Japan, except for one recent case reported from Korea). The origin of this case, outside of its normal geographic location, may be associated with the importation of fish into Spain. The viability of the infective larval stage is evidence of its resistance to export/import conditions. Treatment with paromomycin sulfate did not result in the whole worm being discharged but several short strobilar chains showed drug-induced degeneration.

Animals↗
PubMed1996

Comparison of 2 centrifugation procedures in the formalin-ethyl acetate stool concentration technique for the detection of Cryptosporidium oocysts.

A comparison between the standard formalin-ethyl acetate (FEA) stool concentration procedure (centrifugation at 400 g for 2 min) and a modification proposed to increase the recovery of Cryptosporidium oocysts (500 g for 10 min) was performed on 73 formalin-preserved stool specimens known to be positive for Cryptosporidium. False-negative results were obtained with both methods, but the increase in centrifugation time and force resulted in the detection of a higher number of oocysts and positive samples. The modified procedure had a sensitivity significantly higher than the standard method (99% compared to 86%, P = 0.0045).

Acetates↗
PubMed1996

[Antibiotic resistance in Salmonella enterica: an increasing problem].

OBJECTIVE: To determine the evolution of the frequencies of Salmonella enterica serotypes and their resistance to antimicrobial agents. METHOD: A retrospective study of all S. enterica strains isolated from stool samples in the Hospital Clinico Universitario of Zaragoza over the period 1990-1994. RESULTS: Enteritidis was the most frequently isolated serotype (62.9%), although it showed a progressive decrease (from 76.2% in 1990 to 39.8% in 1994). Typhimurium was the serotype showing the highest resistance levels, 37.1% of its isolates being resistant to ampicillin, streptomycin, chloramphenicol and tetracyclin. There was a distinct increase in the frequency of multiresistant strains, from 9.7% in 1990 to 22.9% in 1994. Of 88 such strains, 78.4% corresponded to serogroup B, whereas only 4.5% to serogroup D. Of the antimicrobial agents traditionally considered elective, only cotrimoxazole maintained acceptable resistance levels (4.4%). Resistance to fluoroquinolones or 3rd-generation cephalosporines was not detected. CONCLUSIONS: The increasing frequency of Typhimurium, a highly resistant serotype, restrains the elective antimicrobial agents to cotrimoxazole in children and fluoroquinolones in adults. 3rd-generation cefalosporines may be a good alternative in case of therapeutic failure.

Drug Resistance, Microbial↗
PubMed1995

Evaluation of the optimal number of faecal specimens in the diagnosis of cryptosporidiosis in AIDS and immunocompetent patients.

This study determines the optimal number of faecal samples that should be examined in order to minimize the occurrence of false-negative results in the diagnosis of cryptosporidiosis using routine techniques. A total of 23,023 faecal samples from 10,870 patients submitted for parasitological examination were processed by the formalin-ethyl acetate concentration technique and stained using a modified Ziehl-Neelsen method. Cryptosporidiosis was diagnosed in 232 patients (2.13%), 44 of whom were infected by HIV, the prevalence rate in this population group being 15.54%. The increase in the number of diagnoses obtained by the examination of n and (n-1) specimens was evaluated statistically. This study found that three is the optimal number of faecal samples that should be examined when cryptosporidiosis is suspected in immunocompetent patients; whereas, only two samples are required for diagnosing this protozoosis in AIDS patients.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Design, formulation, and optimization of media.

The fundamental knowledge available about the microorganism, substrates, and process represent the basis on which a rational approach for the design and formulation of media for microbial processes can be attempted. In this respect, it is necessary to analyze critically the main objective to be optimized (yield, productivity, quality of final product, etc.). The first step of medium development is concerned with the decision to be taken about the adequate components to be used, followed by the calculation of their concentrations. After medium preparation and experimentation, the application of the most appropriate statistical optimization methodology will make it possible to attain the optimal medium. Medium design and formulation for plant cell processes are still carried out on an empirical basis owing to the lack of fundamental knowledge. However, some general guidelines can be given for growth and production media considering the experimental evidence available about the functions and influence of the medium components for promoting growth and product formation. Adequate manipulation of the carbon, nitrogen, and phosphorus sources and phytohormones and the inclusion of precursors and elicitors in the medium represent the best strategy for improving medium development for plant cell processes. The development of cost-effective medium supplies for mammalian cell culture production of proteins is a key element for a commercially successful process. Medium development is a task that requires experience, time, and resources in its solutions, which may be several. An optimal formulation is elusive because there will always be room for improvement, but through systematic, comprehensive work, practical combinations of nutrients, factors, and feeding schedules can be developed in a reasonable time. A properly developed formulation can bring the burden of the medium below 10% of the total cost of a mammalian cell process.

Animals↗
PubMed1994

Hybridoma stability.

Hybridoma stability issues include mutations, chromosome losses, and the potential effects of process variables on the yield, quality and homogeneity of the Monoclonal Antibody (MAb) product. MAb production by murine hybridomas is typically unstable in the early stages after fusion but repeated cloning normally produces stable clones. The stability of hybridomas and the consistency of the MAbs produced during extended high density perfusion cultures at Xoma Corporation were evaluated. Cell stability was assessed by recovering cells from the bioreactors at different intervals and comparing their growth and product formation kinetics and yields to those of cells started fresh from the corresponding Manufacturer's Working Cell Banks. Product consistency was evaluated in the crude harvests and in the corresponding purified MAb lots by biochemical and functionality tests including: SDS-PAGE (reducing and non-reducing), IEF, HPLC (size exclusion and cation exchange), peptide mapping, N-terminal sequencing, carbohydrate composition and binding assays. Several murine hybridomas were studied during runs lasting several months and found to be stable by all criteria employed. Such results support the viability of extended hollow fiber perfusion cultures for reproducible production of murine MAbs. Selecting stable clones and understanding the effects of process variables on the quantity and quality of the MAbs are keys to controlling hybridoma stability during the manufacturing process.

Animals↗
PubMed1993

A reverse transcriptase-polymerase chain reaction assay for the detection and quantitation of murine retroviruses.

Specific hybridization primers for the PCR assay were developed to detect the presence of the ecotropic, xenotropic, and mink cell focus-forming classes of murine leukemia viruses (MuLVs) in samples derived from cultured cells and cell-free supernatants. The primers, which were tested against reference viruses from all three classes and two subclasses and accurately identified each class present, were used to characterize the endogenous expression of MuLV-related sequences in a number of murine and mink cell lines. Two murine/murine hybridomas were shown to contain expressed retroviral sequences from all three classes. The murine cell lines SC-1, Balb/c 3T3, and NIH 3T3, were found to constitutively express sequences from many of the MuLV classes. These MuLV-related sequences were not expressed in the Mus dunni or mink lung cell lines. When these primers were used in a quantitative PCR assay to determine the retroviral content of hybridoma supernatants, the values were less variable than those obtained by transmission electron microscopy (TEM). This assay can be adapted to detect and quantitate any viral contaminant in cell culture supernatants, ascites fluids, process validation samples, and final products.

3T3 Cells↗
PubMed1991

[Epidemiology of shigellosis and colicin typing of Shigella sonnei. A 14-year study].

To study the most important epidemiologic features of shigellosis and the application of colicinotyping as an epidemiologic marker for Shigella sonnei. A total of 44.818 stoll-cultures were performed. We classify, using colicinotyping, 156 Shigella sonnei strains isolated from different patients. The incidence of Shigellosis in our media is low (1.08% of all stool-cultures). It is more frequent in pediatric population and increases on late summer and fall. We had been able to show an increasing incidence, with an hyperendemic situation during a three-years period (1981-1983). Shigella sonnei is the most prevalent species (86% of cases), followed by S. boydii (7.3%) and S. flexneri (5.9%). All S. sonnei strains epidemiologically related showed the same colicinotype. Only two strains were not typable and we identified 9 different colicinotypes, being type 13 (30.8%), type 8 (18.6%), type 6 (17.3%) and type 12 (11.54%) the more frequent types. Colicinotype 8 was the more prevalent between 1978-1979. Type 13 was predominant between 1981 and 1985. During 1987 and 1989, at the same time that incidence had risen, types 6 and 12 were prevalent. The total number of different colicinotypes identified during a single year is never greater than five. Colicinotyping of S. sonnei is a simple typing method that gives enough useful epidemiologic information, discriminative and reproducible. Although there are changes of circulating types incidence and the prevalen colicinotype colud vary from one year to another, during longer periods of time there is a reduced number of alternating colicinotypes, which sets up a situation that could be further classified as endemic.

Adult↗
PubMed1990

Ca transport in membrane vesicles from pinto bean leaves and its alteration after ozone exposure.

The influence of ozone on Ca(2+) transport in plant membranes from pinto bean (Phaseolus vulgaris L. var Pinto) leaves was investigated in vitro by means of a filtration method using purified vesicles. Two transport mechanisms located at the plasma membrane are involved in a response to ozone: (a) passive Ca(2+) influx into the cell and (b) active Ca(2+) efflux driven by an ATP-dependent system, which has two components: a primary Ca(2+) transport directly linked to ATP which is partially activated by calmodulin and a H(+)/Ca(2+) antiport coupled to activity of a H(+)-ATPase. The passive Ca(2+) permeability is increased by ozone. A triangular pulse of ozone stimulates a higher influx of Ca(2+) than does a square wave, even though the total dose was the same (0.6 microliter per liter x hour). Leaves exposed to a square wave did not exhibit visible injury and were still able to recover from oxidant stress by activation of calmodulin-dependent Ca(2+) extrusion mechanisms. On the other hand, leaves exposed to a triangular wave of ozone, exhibit visible injury and lost the ability of extruding Ca(2+) out of the cell.

Journal Article↗
PubMed1989

Alteration of Extracellular Enzymes in Pinto Bean Leaves upon Exposure to Air Pollutants, Ozone and Sulfur Dioxide.

Diamine oxidase and peroxidase, associated with the wall in pinto bean (Phaseolus vulgaris L. var Pinto) leaves, can be washed out by vacuum infiltration and assayed without grinding the leaf. The diamine oxidase activity is inhibited in vivo by exposure of the plants to ozone (dose of 0.6 microliters per liter x hour), whereas the peroxidase activity associated with the wall space is stimulated. This dose does not cause obvious necrosis or chlorosis of the leaf. These alterations are greater when the dose of ozone exposure is given as a triangular pulse (a slow rise to a peak of 0.24 microliters per liter followed by a slow fall) compared to that given as a constant square wave pulse of 0.15 microliters per liter for the same 4 hour period. Exposure of the plants to sulfur dioxide (at a concentration of 0.4 microliters per liter for 4 hours) does not result in any change in the diamine oxidase or peroxidase activities, yet the total sulfhydryl content of the leaf is increased, demonstrating the entry of sulfur dioxide. These two pollutants, with different chemical reactivities, affect the activities of the extracellular enzymes in different manners. In the case of ozone exposure, the inhibition of extracellular diamine oxidase could profoundly alter the movements of polyamines from cell to cell.

Journal Article↗
PubMed1984

Peroxidase Release Induced by Ozone in Sedum album Leaves: Involvement of Ca.

The effect of ozone was studied on the peroxidase activity from various compartments of Sedum album leaves (epidermis, intercellular fluid, residual cell material, and total cell material). The greatest increase following a 2-hour ozone exposure (0.4 microliters O(3) per liter) was observed in extracellular peroxidases. Most of the main bands of peroxidase activity separated by isoelectric focusing exhibited an increase upon exposure to ozone. Incubation experiments with isolated peeled or unpeeled leaves showed that leaves from ozone-treated plants release much more peroxidases in the medium than untreated leaves. The withdrawal of Ca(2+) ions reduced the level of extracellular peroxidase activity either in whole plants or in incubation experiments. This reduction and the activation obtained after addition of Ca(2+) resulted from a direct requirement of Ca(2+) by the enzyme and from an effect of Ca(2+) on peroxidase secretion. The ionophore A23187 promoted an increase of extracellular peroxidase activity only in untreated plants. The release of peroxidases by untreated and ozone-treated leaves is considerably lowered by metabolic inhibitors (3-(3,4-dichlorophenyl)-1,1-dimethylurea and sodium azide) and by puromycin.

Journal Article↗
PubMed1984

Production of amylase by Aspergillus foetidus on rice flour medium and characterization of the enzyme.

Aspergillus foetidus ATCC 10254 was selected from nine starch-utilizing microorganisms for its high amylolytic activity. This mould produced high levels of extracellular alpha-amylase in rice starch medium and degraded the available starch efficiently. Optimal conditions for enzyme production on 2.0% rice medium included 28 degrees C, initial pH of 6.6, and supplementations with 0.02% NaNO2, 0.08% KH2PO4, and 0.08% corn steep liquor. Eleven-fold purification of the enzyme was obtained after ammonium sulphate and ethanol precipitations from spent medium. The molecular weight was estimated at 41 500. Optimum pH and temperature for enzyme activity were 5.0 and 45 degrees C. Michaelis-Menten constants were 1.14 mg/ml on amylopectin, 2.19 mg/ml on soluble starch and 7.65 mg/ml on amylose. Amylose produced substrate inhibition while glucose or maltose did not inhibit the enzyme. This alpha-amylase may be used as a saccharifying enzyme for rice starch. Aspergillus foetidus ATCC 10254 also presents a potential for treatment of starch-containing waste waters.

Aspergillus↗
PubMed1982

Regulation of beta-D-galactosidase synthesis in Candida pseudotropicalis.

Regulation of lactose (beta-D-galactosidase) synthesis in the lactose-utilizing yeast Candida pseudotropicalis was studied. The enzyme was inducible by lactose and galactose. When grown on these sugars the enzyme level of the yeast was 20 times or higher than when grown on glycerol. The Km and optimal pH were similar for the lactase induced either by lactose or galactose. The hydrolysis of o-nitrophenyl-beta-D-galactopyranoside by the lactase was inhibited by galactose and several analogs and galactosides, but not by glucose. Lactose uptake activity observed in lactose-grown cells was very reduced in cells grown on glucose or galactose. Glucose repressed the induction of lactase, but not the metabolic system for galactose utilization. In continuous culture on lactose medium at dilution rates below 0.2 h-1 the specific lactase activity was higher than in batch cultures and decreased with increases in dilution rate. Lactase was induced by pulses of lactose and galactose in cells growing on glucose, but only at low dilution rates were the steady-state concentration of glucose was very low.

Candida↗