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Biomedical subjects

J J Ramos

Publications and source records attributed to J J Ramos.

At least 19 recordsLinked to original sources
PubMed2006

A simple and fast method for the simultaneous determination of polychlorinated biphenyls and polybrominated diphenyl ethers in small volumes of human serum.

A fast extraction and clean-up method for the simultaneous determination of PCBs and PBDEs has been developed. The procedure consisted of a solid-phase extraction (SPE) of the analytes on an Oasis HLB cartridge and the subsequent on-line fat elimination by directly dropping the eluate from the SPE cartridge onto a second cartridge containing layers of activated neutral silica gel and sulphuric acid modified silica gel. Detection limits using a gas chromatography coupled with an ion trap detector in the tandem mass spectrometry mode were from 0.03 to 0.3 pg/microL for PCBs and from 0.07 to 1.3 pg/microL for PBDEs. Repeatability (lower than 11%) and reproducibility (lower than 17%), expressed as relative standard deviation (RSD, n=4), were satisfactory. The feasibility of the method developed for the determination of the target compounds was evaluated by participation in several rounds of interlaboratory exercises involving human serum with a wide range of PBDE and PCB concentrations. The method has been applied to the evaluation of PBDEs and PCBs in human serum samples of up to 1 mL.

Chromatography, Gas↗
PubMed2006

Miniaturised selective pressurised liquid extraction of polychlorinated biphenyls from foodstuffs.

The feasibility of miniaturised pressurised liquid extraction (PLE) with in-cell purification and subsequent gas chromatography with micro-electron capture detection (GC-micro-ECD) for the determination of prioritary and toxic polychlorinated biphenyls (PCBs) in a variety of foodstuffs (fat contents in the range 22-49%, w/w, on a freeze-dried basis) has been investigated. After optimisation of the several experimental parameters affecting the efficiency of the selective PLE process, the developed method provided quantitative recoveries of the endogenous PCBs studied and complete fat elimination in a single step using n-hexane as extraction solvent. A total solvent volume of 3.5 mL was used for the two consecutive 7 min static PLEs of 100-mg samples. Detection limits using GC-micro-ECD were below 0.2 ng/g freeze dried sample for all 22 PCBs investigated in real-life foodstuffs, and the repeatability of the complete PLE plus GC-micro-ECD method as calculated for the analysis of the endogenous PCBs in general was better than 14%. Comparison of the miniaturised PLE method developed with either conventional Soxhlet extraction or matrix solid phase dispersion with subsequent (off-line) clean-up for the analysis of non-spiked samples showed that the efficiency of PLE was similar to or better (recoveries in the range 83-133%, as calculated for the endogenous analytes) than for the other two extraction methods assayed.

Analytic Sample Preparation Methods↗
PubMed2006

Influence of colostrum treated by heat on immunity function in goat kids.

The aim was to evaluate the influence of goat colostrum treated by heat on immune function in kids. Thirteen newborn kids were fed untreated colostrum (group A) and 13 kids were fed colostrum treated by heat (56 degrees C, 30 min) (group B). Blood samples were obtained at eight time points between the ages of 0 h to 28 days. Serum protein fractions, IgG levels and phagocytic activity of neutrophils were determined. A delayed type hypersensitivity (DTH) test was used, clinical status and body weight was recorded. There were no clinical signs of disease and no differences (P>0.05) on body weight between groups were noted. Kids from group B had less total protein levels and gamma-globulins than kids from group A (P<0.05). A decrease in serum IgG levels (P<0.05) was observed in kids from group B during all experiment. DTH response in kids from group B was lower (P<0.01) than group A, suggesting alteration on cellular immune system. No effects on phagocytic activity of the neutrophils were observed when both groups were compared (P>0.05). These results showed that colostrum treated by heat impaired some immunological parameters in kids, but these changes did not affect on clinical status or performance.

Animals↗
PubMed2005

Faecal thiaminase, plasma lactate and pyruvate concentrations and erythrocyte transketolase activity changes in apparently normal replacement ewes after the initiation to the pasture.

A study was made to investigate faecal thiaminase and the thiamine-related biochemical changes in apparently normal replacement ewes with a feed change, after the initiation without adaptation to the new pasture. Twenty-four female ewes were divided into two groups. Group A was managed in a system based on pasture and was compared with group B system based on a diet of concentrate and straw until moving to pasture 9 weeks after. Blood samples for lactate, pyruvate and erythrocyte transketolase activity determinations and faeces for thiaminase estimation were evaluated chronologically. At the end of a 126 days experimental period, live weights of groups were similar. We confirmed that clinically normal sheep may have thiaminase activity in the faeces and concluded that the thiaminase release increased during the diet changes, from concentrate to pasture, and that their continued excretion could develop some degree of thiamine deficiency.

Animal Feed↗
PubMed2005

High prevalence of ulcerative posthitis in Rasa Aragonesa rams associated with a legume-rich diet.

This study describes an outbreak of ulcerative posthitis that eventually affected 76 of 80 of rams in a flock of Rasa Aragonesa sheep on a legume-rich diet. Lesions were confined to the prepuce and varied from mild hyperaemia to ulcerations. Corynebacterium renale was isolated from the lesions. Treatment of an initial group of 17 was based on a change of diet and topical treatment with Veterin Banedif with prednisolone once a day for 15 days and was successful. Lesions in this group were completely resolved after 15 days. The relationship between a legume-rich diet, ruminal alkalosis, elevated urine pH and posthitis is discussed.

Animal Feed↗
PubMed2004

Miniaturization in sample treatment for environmental analysis.

The increasing demand for faster, more cost-effective and environmentally friendly analytical methods is a major incentive to improve the classical procedures used for sample treatment in environmental analysis. In most classical procedures, the use of rapid and powerful instrumental techniques for the final separation and detection of the analytes contrasts with the time-consuming and usually manual methods used for sample preparation, which slows down the total analytical process. The efforts made in this field in the past ten years have led to the adaptation of existing methods and the development of new techniques to save time and chemicals, and improve overall performance. One route has been to develop at-line or on-line and, frequently, automated systems. In these approaches, miniaturization has been a key factor in designing integrated analytical systems to provide higher sample throughput and/or unattended operation. Selected examples of novel developments in the field of miniaturized sample preparation for environmental analysis are used to evaluate the merits of the various techniques on the basis of published data on real-life analyses of trace-level organic pollutants. Perspectives and trends are briefly discussed.

Journal Article↗
PubMed2003

Biochemical changes in apparently normal sheep from flocks affected by polioencephalomalacia.

Blood samples were obtained for determination of the activities of lactate, pyruvate and erythrocyte transketolase, and faeces as samples for estimation of thiaminase, from 190 apparently healthy sheep from 19 flocks in which at least one animal had been diagnosed with polioencephalomalacia (PEM), from 59 control animals and from 7 affected by PEM. Feed and pasture grass samples were collected for thiaminase analysis and thiaminase was assayed in ryegrass and fescue. Decreased erythrocyte transketolase activity, accompanied by a corresponding rise in the thiamin pyrophosphate effect, and estimation of the thiaminase content in faeces, may be useful diagnostic procedures by which to identify periods of greater risk, during which animals could develop PEM. The changes in the diet probably acted as a primary factor for microbial production of thiaminases in replacement ewes. In these, the prevalence was higher in the spring months.

Animals↗
PubMed2002

Driven reconnection about a magnetic X-line with strong guide component.

A two-dimensional, two-fluid model is used to investigate driven magnetic reconnection in collisionless or semicollisional plasmas. The reconnection is driven by externally induced plasma flows in a background magnetic configuration that has a hyperbolic null component in the reconnection plane and a strong component, the so-called guide component, perpendicular to that plane. A dynamic solution is obtained in which the reconnection proceeds in two phases: an initial one whose characteristic rate is a fraction of the Alfvén frequency, and a later one whose rate is determined by the electron collision frequency.

Journal Article↗
PubMed2001

Molecular mobility and fragility in indomethacin: a thermally stimulated depolarization current study.

PURPOSE: To show that thermally stimulated depolarization currents (TSDC), which is a dielectric experimental technique relatively unknown in the pharmaceutical scientists community, is a powerful technique to study molecular mobility in pharmaceutical solids, below their glass transition temperature (Tg). Indomethacin (Tg = 42 degrees C) is used as a model compound. METHODS: TSDC is used to isolate the individual modes of motion present in indomethacin, in the temperature range between -165 degrees C and +60 degrees C. From the experimental output of the TSDC experiments, the kinetic parameters associated with the different relaxational modes of motion were obtained, which allowed a detailed characterization of the distribution of relaxation times of the complex relaxations observed in indomethacin. RESULTS: Two different relaxational processes were detected and characterized: the glass transition relaxation, or alpha-process, and a sub-Tg relaxation, or secondary process. The lower temperature secondary process presents a very low intensity, a very low activation energy, and a very low degree of cooperativity. The fragility index (Angell's scale) of indomethacin obtained from TSDC data is m = 64, which can be compared with other values reported in the literature and obtained from other experimental techniques. CONCLUSIONS: TSDC data indicate that indomethacin is a relatively strong glass former (fragility similar to glycerol but lower than sorbitol, trehalose, and sucrose). The high-resolution power of the TSDC technique is illustrated by the fact that it detected and characterized the secondary relaxation in indomethacin, which was not possible by other techniques.

Calorimetry↗
PubMed2000

Effect of acute hyperglycaemia on the serum fructosamine and blood glycated haemoglobin concentrations in canine samples.

The effect was studied of an acute and non-persistent hyperglycaemia on the serum fructosamine and blood glycated haemoglobin concentrations in canine samples. Five dogs were given glucose solution intravenously and blood samples were taken from each dog before and at 5, 15, 30, 60 and 120 min and 24 h after the infusion. There was an intense hyperglycaemia 5 min after the injection was given, but no statistically significant differences in the serum fructosamine and glycated haemoglobin were observed. It was concluded that an acute and transient hyperglycaemia does not cause significant changes in the glycated haemoglobin and fructosamine concentrations in healthy dogs.

Acute Disease↗
PubMed1997

Serological serum protein fraction and responses to Brucella melitensis in lambs fed aflatoxins.

Twenty-four lambs were given 2 ppm aflatoxins (AF) in their diet for 37 d and 12 were kept as a control group. After this time, toxic feed was removed for a further 35 days (clearance period). On day 17 all lambs were vaccinated with B melitensis strain Rev-1, and blood samples were taken regularly to determine the levels of antibodies and serum proteins. Aflatoxins decreased titers of Rose Bengal test and optical densities of ELISA, both in the intoxicated and clearance periods. Complement fixation titers were lower in intoxicated lambs, except on the 23rd day of intoxication, but not statistically different (P > 0.05). No effect of AF was noted on total serum proteins, but albumin and alfa-globulin levels were lower for intoxicated lambs than for the control group. Beta-globulin concentration did not change, and increases in gamma-globulins levels in dosed lambs were observed throughout the experiment. These results suggest that AF causes a failure in the acquired immunity system of lambs by decreasing antibody production and altering serum profile proteins.

Aflatoxins↗
PubMed1996

Comparison of indirect immunofluorescent antibody test and modified direct agglutination test methods for detection of Toxoplasma gondii antibodies in adult sheep in Spain.

A total of 2306 serum samples obtained from adult sheep were analysed for Toxoplasma gondii IgG antibodies by modified direct agglutination test and indirect immunofluorescence assay test. Similar results were obtained with both procedures (seroprevalence of 35.27% for modified direct agglutination test and 33.72% for indirect immunofluorescence assay test at dilution 1:80), but some differences in relation to sample dilution were registered. All the titers assayed (dilution two-fold from 1:40 to 1:320) can be used in diagnosis with both procedures, but titers 1:80 are recommended for screening studies in ovine flocks.

Agglutination Tests↗
PubMed1995

Changes in the prothrombin time, haematology and serum proteins during experimental aflatoxicosis in hens and broiler chickens.

Two groups of 32 laying hens and two groups of 32, 23-day-old broiler chickens were given 2.5 and 5 mg kg-1 of aflatoxin in their diet for four, eight, 16 and 32 days; 16 hens and 32 broiler chicks served as control groups. In the laying hens, aflatoxicosis was characterised mainly by an increase in prothrombin time, and decreases in total plasma proteins and albumin levels; there were increases in red blood cell (RBC) counts and haematocrit which were greater in the group fed 5 mg kg-1. There was a decrease in beta-globulins and an increase in gamma-globulins. In the broiler chickens, there was only a slight increase in prothrombin time and a decrease in RBC counts. This data proves the good sensitivity and utility of prothrombin time values as an indicator of aflatoxicosis in birds.

Aflatoxins↗
PubMed1995

Changes in the coagulation profile of lambs intoxicated with aflatoxin in their feed.

Twenty-three male lambs were intoxicated with 2.5 ppm aflatoxins in their feed for a period of 3 weeks. Thirteen lambs were maintained as a control group (0 ppm aflatoxins in their feed). The coagulation profiles were determined from blood samples that were obtained at 0, 7, 14 and 21 d during the intoxication period and at 1, 2, 4 and 8 d of an 8-d clearance period. Aflatoxicosis in the animals was characterized by an increase in prothrombin time (P < 0.01) from d 14 of the intoxication period until the end of the experiment. An increase (P < 0.05) in fibrinogen concentration was detected beginning on d 21, instead of the expected decrease. This was probably due to the inflammation found in the lungs of the intoxicated animals. No difference in activated partial thromboplastin time was found between intoxicated and control animals. These results suggest that there was a significant change in some coagulation factors of the extrinsic pathway in the intoxicated lambs and that prothrombin time determination could be used as an indicator of aflatoxicosis in lambs.

Aflatoxins↗
PubMed1994

Vitamin B12 levels in ewe colostrum and milk and in lamb serum.

Vitamin B12 was measured in samples of normal ovine colostrum and milk and in sera of lambs and ewes taken at various stages of lactation, from lambing up to 16 d. Colostrum obtained within 24 h of lambing contained high concentrations of vitamin B12, but within a few days the levels fell. The lambs received high levels of vitamin B12 from their dams' colostrum but a parallel decrease of vitamin B12 levels in lambs' serum and ewes' milk was subsequently observed. Milk vitamin B12 was analysed by the microbiological method (Lactobacillus leichmannii, ATCC 7830) and a radioisotope dilution (RID) technique. Milk vitamin B12 concentrations were greater with the microbiological technique compared with the RID method. The radioassay method has been shown to be as reliable as the microbiological method for measuring vitamin B12 in ovine milk except for very low levels.

Animals↗