Biomedical subjects

M J Díaz

Publications and source records attributed to M J Díaz.

At least 19 recordsLinked to original sources

PubMed2006

Toxicokinetics of lambda-cyhalothrin in rats.

The toxicokinetics of lambda-cyhalothrin after single 20 mg kg(-1) oral and 3 mg kg(-1) intravenous doses were studied in rats. Serial blood samples were obtained after oral and intravenous administration. Liver, brain, spinal cord, sciatic nerve, vas deferens, anococcygeus and myenteric plexus tissue samples were also collected. Plasma, liver, hypothalamus, cerebellum, medulla oblongata, frontal cortex, striatum, hippocampus, midbrain, spinal cord, vas deferens, anococcygeus, myenteric plexus and sciatic nerve concentrations of lambda-cyhalothrin were determined by HPLC. The plasma and tissue concentration-time data for lambda-cyhalothrin were found to fit a two-compartment open model. For lambda-cyhalothrin, the elimination half-life (T1/2beta) and the mean residence time from plasma were 7.55 and 8.55 h after i.v. and 10.27 and 14.43 h after oral administration. The total plasma clearance was not influenced by dose concentration or route and reached a value of 0.060l h(-1)kg(-1). After i.v. administration, the apparent volume of distribution and at steady state were 0.68 and 0.53l kg(-1), suggesting a diffusion of the pyrethroid into tissue. After oral administration, lambda-cyhalothrin was extensively but slowly absorbed (Tmax, 2.69 h). The oral bioavailability was found to be 67.37%. Significant differences in the kinetic parameters between nervous tissues and plasma was observed. The maximum concentrations in hypothalamus (Cmax, 24.12 microg g(-1)) and myenteric plexus (Cmax, 25.12 microg g(-1)) were about 1.5 times higher than in plasma (Cmax, 15.65 microg ml(-1)) and 1.3 times higher than in liver (Cmax, 18.42 microg ml(-1)). Nervous tissue accumulation of lambda-cyhalothrin was also reflected by the area under the concentration curve ratios of tissue/plasma (liver). The T1/2beta for lambda-cyhalothrin was significantly greater for the nerve tissues, including neuromuscular fibres, (range 12-26 and 15-34 h, after i.v. and oral doses) than for plasma (7.55 and 10.27 h, respectively).

Administration, Oral↗

PubMed2004

Pharmacokinetics of amoxycillin and the rate of depletion of its residues in pigs.

Six pigs were used in a two-period crossover study to investigate the pharmacokinetics of amoxycillin after single intravenous and oral doses of 20 mg/kg bodyweight. Twelve pigs were used to study the residues of the drug in muscle, kidney, liver and fat after they had received daily oral doses of 20 mg/kg amoxycillin for five days. The mean (sd) elimination half life (t1/2beta) and mean residence time of amoxycillin in plasma were 3.38 (0.30) and 3.54 (0.43) hours, respectively, after intravenous administration and 4.13 (0.50) and 4.47 (0.30) hours, respectively, after oral administration. After oral administration, the maximum plasma concentration (Cmax) was 7.37 (0.42) microg/ml and it was reached after 0.97 (0.29) hours. Six days after the last oral dose, the mean concentration of amoxycillin in the pigs' kidneys was 21.38 ng/g and in the liver it was 12.32 ng/g, but no amoxycillin could be detected in fat or muscle; the concentrations of amoxycillin in edible tissues were less than the European Union maximal residue limit of 50 microg/kg.

Adipose Tissue↗

PubMed2003

Optimization of hydrogen peroxide in totally chlorine free bleaching of cellulose pulp from olive tree residues.

The influence of the operating conditions used in the bleaching of olive wood trimmings pulp (viz. hydrogen peroxide concentration and time) on the yield, kappa index and viscosity of the resulting pulp and on strength-related properties of paper sheets was studied to determine the optimal bleaching conditions of this pulp. Hydrogen peroxide bleached pulps at different sequences (oxygen, ozone, chlorine dioxide and alkaline extractions) were compared. Hydrogen peroxide bleaching proved to be suitable for this pulp. Considerable improvements in viscosity were obtained with respect to other bleaching sequences such as oxygen, ozone and chlorine dioxide. Hydrogen peroxide bleaching decreased the kappa index 51.3% less than ozone bleaching, 25.0% less than chlorine dioxide (D) and 6.3% less combined chlorine dioxide-alkaline extraction (DE). To obtain kappa indices 50.9% and 37.9% lower than the index achieved by hydrogen peroxide, oxygen (LaO(p)) and ozone (LaO(LaZ)R) sequences respectively were needed. Lower-medium levels of hydrogen peroxide concentrations (1-3%) and high reaction times (210 min) proved to be suitable for bleaching of pulp olive trimming residues. This approach could be used on this residue to produce adequately bleached pulp.

Cellulose↗

PubMed2003

Hydrothermal and pulp processing of Eucalyptus.

Hydrothermal processing of Eucalyptus wood was performed at operation temperature of 181 degrees C, processing time or 37.5 min and solid water ratio of 1/6 to ensure a maximum loss of xylan recuperation with minimum cellulose fibre degradation. Under those conditions, the loss of xylan was 22% less than that achieved with the conditions 196 degrees C, 50.6 min and 1/8 (solid/water). IN In addition, an experimental design was used to study the influence of process variables: temperature (145-175 degrees C), pulping time (40-120 min) and ethanol concentration (40-70% weight concentration), on the properties of pulps (yield, kappa number, viscosity, cellulose, xylan, lignin acetyl groups contents and brightness) and paper sheets (stretch index, burst index and tear index) obtained from the solid fraction after hydrothermal treatment of Eucalyptus globulus. Pulps with acceptably high physical and chemical properties can be obtained operating at 175 degrees C for 90 min with 55% ethanol concentration.

Cellulose↗

PubMed2001

Co-composting of sugarbeet vinasse: influence of the organic matter nature of the bulking agents used.

Two composts were obtained by co-composting of a concentrated depotassified beet vinasse and two agricultural solid residues with different organic matter nature: grape marc (GM; lignin waste) and cotton gin trash (C; cellulosic waste). Composting was carried out in aerated piles with mechanical turning, in controlled conditions during 4 months. After 71 days of composting, a new addition of vinasse similar to the initial addition was made. Changes in temperature, pH and inorganic nitrogen followed a similar path for both mixtures. However, organic matter fractions showed different behaviour depending on the material co-composted with vinasse. Lower organic matter degradation was observed when GM was used as bulking agent due to its high lignin content. No phytotoxicity was detected in the end products. The chemical and physical properties of both vinasse composts suggest their possible use as fertiliser.

Biodegradation, Environmental↗

PubMed2001

Assessment of a preclinical training system with indirect vision for dental education.

The aim of the present study is the evaluation of a pre-clinical training system using indirect vision for dental education purposes. The study population was undergraduate dental students between the ages of 18-20, at the beginning of their first dental course. From a total of 105 students, those presenting some condition that would have had influence on their manual skills and those who for some circumstance left the study after beginning it were excluded, resulting in 69 students (51 female and 18 male) taking part in the study. The study design involved two sessions separated by a 7-day interval in which the students used a reflection box to develop psychomotor skills in mirror use. In every session they performed an initial evaluation test, some training exercises and a final evaluation test. The evaluation tests and the training exercises consisted in following a curved, straight or convoluted shape in the reflection box. Four groups of students were used who trained in different ways using curved or straight lines. Evaluation of the tests was based on the number of errors made and the time to completion. All students showed an improvement in their performance of following curved and straight lines with indirect vision after this form of training. The results after the first training session were statistically significant, while the further improvement was not significant after the 2nd training session. Those students who trained first with curved lines and later with straight lines produced more errors than the other groups. Female students performed better than male students in this assessment.

Adolescent↗

PubMed2001

Pharmacokinetics and residues of ciprofloxacin and its metabolites in broiler chickens.

The pharmacokinetic properties of ciprofloxacin and its metabolites were determined in healthy chickens after single i.v. and oral dosage of 8 mg ciprofloxacin kg(-1) bodyweight. After i.v. and oral administration, the plasma concentration-time graph was characteristic of a two-compartment open model. Mean (SD) elimination half-life and mean residence time of ciprofloxacin in plasma were 8.84 (2.13) and 8.54 (1.64) hours, respectively, after i.v. administration and 11.89 (1.95) and 13.32 (2.65) hours, respectively, after oral administration. Mean maximal plasma concentration of ciprofloxacin was 2.63 (0.20) microg ml(-1), and the interval from oral administration until maximum concentration was 0.36 (0.07) hours. The mean oral bioavailability of ciprofloxacin was found to be 69.12 (6.95) per cent. Ciprofloxacin was mainly converted to oxociprofloxacin and desethyleneciprofloxacin. Considerable kidney, liver, muscle and skin + fat tissue concentrations of ciprofloxacin and its metabolites oxociprofloxacin and desethyleneciprofloxacin were found when ciprofloxacin was administered orally (8 mg kg(-1) on 3 successive days). It was estimated that mean tissue concentrations of ciprofloxacin and its metabolites ranging between 0.011 to 0.75 microg g(-1) persisted for 5 days.

Administration, Oral↗

PubMed2000

Cytotoxicity in pig hepatocytes induced by 8-quinolinol, chloramine-T and natamycin.

The potential cytotoxic effects of the compounds 8-quinolinol, chloramine-T and natamycin have been studied in isolated pig hepatocytes. The relative cytotoxicity of these compounds was evaluated on the basis of the leakage of cytosolic lactate dehydrogenase (LDH), 3-(4,5 dimethyl)thiazol-2-yl,-2,5-diphenyl tetrazolium bromide (MTT) reduction by mitochondrial dehydrogenases, uptake of neutral red (NR) by cytosolic lysosomes, glutathion (GSH) depletion and oxidized glutathion (GSSG) efflux after 24 h exposure. Evaluation of the 20%, 50% and 80% reduced absorbance data obtained from the parameters NR20, NR50, and NR80, and MTT20, MTT50 and MTT80 enabled us to rank these compounds in decreasing order of cytotoxicity: 8-quinolinol > natamycin > chloramine-T. Also for the parameters LDH and GSH, chloramine-T appears to be less cytotoxic than natamycin and 8-quinolinol. Our study demonstrated that pig hepatocytes may be a useful model for examining cytotoxic events of drugs to be used in pigs, therefore avoiding possible extrapolation problems due to species differences.

Animals↗

PubMed1999

Pharmacokinetic variables and tissue residues of enrofloxacin and ciprofloxacin in healthy pigs.

OBJECTIVES: To determine pharmacokinetics of enrofloxacin and its metabolite ciprofloxacin after a single i.v. and i.m. administration of enrofloxacin and tissue residues after serial daily i.m. administration of enrofloxacin in pigs. ANIMALS: 20 healthy male pigs. PROCEDURE: 8 pigs were used in a crossover design to investigate pharmacokinetics of enrofloxacin after a single i.v. and i.m. administration (2.5 mg/kg of body weight). Twelve pigs were used to study tissue residues; they were given daily doses of enrofloxacin (2.5 mg/kg, i.m. for 3 days). Plasma and tissue concentrations of enrofloxacin and ciprofloxacin were determined. Residues of enrofloxacin and ciprofloxacin were measured in fat, kidney, liver, and muscle. RESULTS: Mean (+/-SD) elimination half-life and mean residence time of enrofloxacin in plasma were 9.64+/-1.49 and 12.77+/-2.15 hours, respectively, after i.v. administration and 12.06+/-0.68 and 17.15+/-1.04 hours, respectively, after i.m. administration. Half-life at alpha phase of enrofloxacin was 0.23+/-0.05 and 1.94+/-0.70 hours for i.v. and i.m. administration, respectively. Maximal plasma concentration was 1.17 +/-0.23 microg/ml, and interval from injection until maximum concentration was 1.81+/-0.23 hours. Renal and hepatic concentrations of enrofloxacin (0.012 to 0.017 microg/g) persisted for 10 days; however, at that time, ciprofloxacin residues were not detected in other tissues. CONCLUSIONS AND CLINICAL RELEVANCE: Enrofloxacin administered i.m. at a dosage of 2.5 mg/kg for 3 successive days, with a withdrawal time of 10 days, resulted in a sum of concentrations of enrofloxacin and ciprofloxacin that were less than the European Union maximal residue limit of 30 ng/g in edible tissues.

Animals↗

PubMed1998

Analysis of cations in drainage water and soil solution by single-column ion chromatography.

Single-column ion chromatography (SCIC) for cation determination in drainage water and soil solution was tested. Using a 100-microliter sample loop, the SCIC detection limits were 0.04 mg l-1 for Na+, 0.02 mg l-1 for NH4-N, 0.06 mg l-1 for K+, 0.05 mg l-1 for Mg2+, and 0.085 mg l-1 for Ca2+. Results were highly reproducible in wide ranges of concentrations. Results obtained by the SCIC method were compared with those by atomic emission spectrometry (Na+ and K+) and atomic absorption spectrometry (Mg2+ and Ca2+). Student's t-test and regression analysis showed that corresponding methods agree closely.

Calcium↗

PubMed1998

Squamous cell carcinoma and infection in a solitary hepatic cyst.

Solitary benign non-parasitic hepatic cysts (SBNHC) are rare congenital cystic abnormalities. Complications of SBNHC include infection, perforation, spontaneous haemorrhage, torsion and neoplastic degeneration. Squamous cell carcinoma is an exceedingly rare entity, which usually arises from metaplastic and subsequent neoplastic transformation of pre-existing cyst of the liver. We report a new case of squamous cell carcinoma of the liver in a non-parasitic solitary hepatic cyst infected by aerobic mixed flora at the time of diagnosis.

Aged↗

PubMed1995

Pharmacokinetics and residues of enrofloxacin in chickens.

The pharmacokinetic properties of enrofloxacin were determined in broiler chickens after single IV and orally administered doses of 10 mg/kg of body weight. After IV and oral administrations, the plasma concentration-time graph was characteristic of a two-compartment open model. The elimination half-life and the mean +/- SEM residence time of enrofloxacin for plasma were 10.29 +/- 0.45 and 9.65 +/- 0.48 hours, respectively, after IV administration and 14.23 +/- 0.46 and 15.30 +/- 0.53 hours, respectively, after oral administration. After single oral administration, enrofloxacin was absorbed slowly, with time to reach maximal plasma concentration of 1.64 +/- 0.04 hours. Maximal plasma concentration was 2.44 +/- 0.06 micrograms/ml. Oral bioavailability was found to be 64.0 +/- 0.2%. Statistically significant differences between the 2 routes of administration were found for the pharmacokinetic variables--half-lives of the distribution and elimination phase and apparent volume of distribution and volume of distribution at steady state. In chickens, enrofloxacin was extensively metabolized into ciprofloxacin. Residues of enrofloxacin and the major metabolite ciprofloxacin in fat, kidney, liver, lungs, muscles, and skin were measured in chickens that received an orally administered dose of 10 mg/kg once daily for 4 days. The results indicate that enrofloxacin and ciprofloxacin residues were cleared slowly. Mean muscle, liver, and kidney concentrations of the metabolite ciprofloxacin ranging between 0.020 and 0.075 micrograms/g persisted on day 12 in chickens after dosing. However, at the time of slaughter (12 days), enrofloxacin residues were only detected in liver and mean +/- SEM concentration was 0.025 +/- 0.003 micrograms/g.

Administration, Oral↗

PubMed1992

[Calibration and safety of sphygmomanometers in health centers of Murcia].

OBJECTIVE: To find the levels of calibration, safety and physical faults in the sphygmomanometers used in Health Centres. DESIGN: A multi-centre, observational, descriptive and crossover study. SITE. 7 Health Centres in the urban zone of Murcia and nearby towns. All the sphygmomanometers in the 7 Health Centres, that is 80 aneroid and 62 mercury ones. MAIN MEASUREMENTS AND RESULTS: It needs high-lighting that 43.7% of the aneroid sphygmomanometers and 12.3% of the mercury ones were wrongly calibrated. We noted that 20% of the measurements made with wrongly calibrated aneroid sphygmomanometers had a margin of error above +/- 8 mmHg, with a tendency towards under-registering. We found very significant differences between the average arterial pressure measured by aneroid instruments as against mercury ones (p < 0.001). The number of sphygmomanometers which show a margin of error greater than +/- 3 mmHg at every level of pressure is significantly greater in aneroid instruments than in mercury ones (p < 0.001). We found physical faults in 23.9% of the instruments. CONCLUSIONS: We consider the number of wrongly calibrated aneroid sphygmomanometers to be excessively high. Therefore mercury ones should be used whenever possible and particularly during diagnosis and treatment. Both aneroid and mercury sphygmomanometers should be regularly checked, using a proper procedure. Mercury instruments set at zero are correctly calibrated and can be used as a model for checking aneroid ones.

Blood Pressure Determination↗

PubMed1992

Pharmacokinetics of norfloxacin and its N-desethyl- and oxo-metabolites in broiler chickens.

Norfloxacin was given to 2 groups of chickens (8 chickens/group) at a dosage of 8 mg/kg of body weight, IV and orally. For 24 hours, plasma concentration was monitored serially after each administration. Another group of chickens (n = 30) was given 8 mg of norfloxacin/kg orally every 24 hours for 4 days, and plasma and tissue concentrations of norfloxacin and its major metabolites desethylenenorfloxacin and oxonorfloxacin were determined serially after the last administration of the drug. Plasma and tissue concentrations of norfloxacin, desethylenenorfloxacin, and oxonorfloxacin were measured by use of high-performance liquid chromatography. Pharmacokinetic variables were calculated, using a 2-compartment open model. For norfloxacin, the elimination half-life (t1/2 beta) and the mean +/- SEM residence time for plasma were 12.8 +/- 0.59 and 15.05 +/- 0.81 hours, respectively, after oral administration and 8.0 +/- 0.3 and 8.71 +/- 0.23 hours, respectively, after IV administration. After single oral administration, norfloxacin was absorbed rapidly, with Tmax of 0.22 +/- 0.02 hour. Maximal plasma concentration was 2.89 +/- 0.20 microgram/ml. Oral bioavailability of norfloxacin was found to be 57.0 +/- 2.4%. In chickens, norfloxacin was mainly converted to desethylenenorfloxacin and oxonorfloxacin. Norfloxacin parent drug and its 2 major metabolites were widely distributed in tissues. Considerable tissue concentrations of norfloxacin, desethylenenorfloxacin, and oxonorfloxacin were found when norfloxacin was administered orally (8 mg/kg on 4 successive days). The concentration of the parent fluoroquinolone in fat, kidneys, and liver was 0.05 micrograms/g on day 12 after the end of dosing.

Animals↗

PubMed1991

Effect of deltamethrin on antipyrine pharmacokinetics and metabolism in rat.

The effect of deltamethrin pretreatment on the pharmacokinetics and metabolism of antipyrine was studied in male rats. The total plasma clearance of antipyrine was significantly decreased by deltamethrin pretreatment (20 mg/kg and 40 mg/kg daily for 6 days prior to antipyrine administration), while the elimination half-life at beta phase, the area under the concentration-time curve and the mean residence time of antipyrine were significantly increased. The magnitude of the observed changes was dose dependent. The urinary excretion of norantipyrine, 4-hydroxyantipyrine and 3-hydroxymethylantipyrine was decreased by 39%, 32% and 26%, respectively (p less than 0.001) in the presence of deltamethrin. In addition, the rate constants for formation of each of these metabolites were significantly decreased by an average of approximately 71%. These results suggest that deltamethrin is capable of inhibiting oxidative metabolism, a finding which could be of clinical and toxicological significance.

Animals↗

PubMed1991

Role of central dopaminergic pathways in the neural control of growth hormone secretion in normal men: studies with metoclopramide.

The aim of this study was to gain further insight into the role that central dopaminergic pathways play in GH neuroregulation in man. Our experimental hypothesis was based on the possibility that most of the controversies on DA role could be due to the fact that the hypothalamic somatotroph rhythm (HSR) was not taken into account when interpreting the GH responses after pharmacological manipulations on dopaminergic pathways. In 10 normal subjects we monitored the effect of central dopaminergic blockade, achieved with metoclopramide (MCP; 10 mg, i.v. bolus), on the pattern of spontaneous GH secretion and the GH responses to a GHRH challenge (GRF1-29, 1 microgram/kg, i.v. bolus) administered together with MCP or 60 min after this drug was given. The study of HSR was made according to our previous postulate. Our results indicate that MCP administration, either prior to or together with the GHRH bolus, significantly increased GHRH-induced GH release during a refractory HSR phase; but not when the GHRH challenge took place during a spontaneous secretory phase. The strong relationship between pre-GHRH plasma GH values and GHRH-elicited GH peaks was lost when MCP was given. These data indicate that MCP was able to disrupt the intrinsic HSR by inhibiting the hypothalamic release of somatostatin (SS). While a main conclusion would be that central DA is a secretagogue for SS secretion, our results also suggest that this role could be dependent on its effects on the adrenergic inputs to SS neurons.

Adult↗

PubMed1990

Pharmacokinetics of pipemidic acid in chickens after single intravenous and oral dosings.

The pharmacokinetics of pipemidic acid after 2 single doses were studied in broiler chickens. Chickens were given single IV and oral doses of 10 and 30 mg of pipemidic acid/kg of body weight. Blood samples were collected over 8 hours after each dose administration. High-pressure liquid chromatography with UV detection was used to determine concentrations in plasma of pipemidic acid. The plasma concentration-time curves after IV administration followed 2-compartment characteristics, rapid initial distribution phase, and a terminal elimination phase. The pharmacokinetic variables differed significantly between single doses of 10 and 30 mg of pipemidic acid/kg. Mean disposition variables were a half-life at alpha phase of 0.06 hours or 0.33 hours, a half-life at beta phase of 1.18 hours or 1.72 hours, a volume of distribution in the central compartment of 0.12 L/kg or 0.31 L/kg, a volume of distribution during the elimination beta phase of 1.64 L/kg or 1.05 L/kg, and a total plasma clearance of 0.97 L/h.kg or 0.41 L/h.kg, for the 10 or 30 mg/kg dose, respectively. After oral administration, the pipemidic acid plasma profile could be adequately described by a 1-compartment model. After the single oral doses of 10 and 30 mg of pipemidic acid/kg, pipemidic acid was absorbed rapidly (time to maximal concentration of 0.31 hours or 0.71 hours) and eliminated with a mean half-life of 0.86 hours or 0.61 hours, respectively. The bioavailability was 39% at 10 mg of pipemidic acid/kg and 61% at 30 mg of pipemidic acid/kg.

Administration, Oral↗

PubMed1989

[Extrahepatic biliodigestive anastomoses. Analysis of 227 cases].

The authors analyze their experience with 227 biliodigestive anastomoses to compare the early and late results. Choledocholithiasis (49%) and cancer of the pancreas (25%) were the most common processes. Choledochoduodenostomy (48%), cholecystojejunostomy (22%), sphincteroplasty (18%) and hepaticojejunostomy (9%) were the techniques most often used. In 61% of cases (90% of the malignant tumors) there was an emergency indication. Twenty-one percent of the patients presented serious complications in the postoperative period (14% of the benign tumors), half of which depended on the bypass. Postoperative peritonitis (2%), external biliary fistula (4%) and acute pancreatitis (2%) were the most significant surgical complications. Hepaticojejunostomy induced the largest number of bypass-dependent complications. There were 12 deaths due to medical causes (5%), these being most numerous in subjects with neoplasms and cholecystojejunostomy, and 8 of surgical origin (4%), half of them in carriers of a hepaticojejunostomy. There was a clear decline in the morbidity of patients operated on in recent years. In the long term, 91% of the patients remained free of discomfort or had minimal symptoms. Choledochoduodenostomy or sphincteroplasty produced the best results. It is concluded that biliodigestive anastomoses yield the best early and late results with minimal secondary effects.

Adolescent↗