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Biomedical subjects

M Sierra

Publications and source records attributed to M Sierra.

At least 55 records · Page 3Linked to original sources
PubMed1997

Pharmacokinetics of levamisole in sheep after intravenous administration.

The pharmacokinetics of levamisole at doses of 5, 7.5 and 10 mg/kg were determined after its intravenous administration to eighteen healthy Merino sheep. Using compartmental analysis, the disposition of the drug best fitted a two-compartmental open model. The mean values for the compartmental volume of distribution at steady state (Vss) were 2.034 +/- 0.23 I, 2.347 +/- 0.720 and 2.001 +/- 0.367 I/kg for each dose, respectively, and values obtained using the statistical moment theory were 2.141 +/- 0.269,2.390 +/- 0.536 and 2.140 +/- 0.345 l/kg for each dose, respectively. There were no dose-related differences (one-way ANOVA) in the constants describing distribution and elimination phases (alpha and beta) or Vss, but significant differences were detected in the total body clearance (Cl) and the area under the plasma concentration-time curve (AUC). After non-compartmental analysis, no significant differences were found when the parameters lambda (the linear terminal slope) and Vss were compared, but significant differences were detected in Cl and AUC. There were no significant differences between the values obtained using the compartmental and non-compartmental analysis when lambda -beta, Cl, Vss, and AUC were compared.

Journal Article↗
PubMed1997

Depersonalization: a conceptual history.

As with other clinical phenomena, the historical analysis of the term, concepts and behaviours involved in the construction of 'depersonalization' should provide researchers with an essential frame for its empirical study. Before the term was coined in 1898, and under a variety of names, behaviours typical of 'depersonalization' were reported by Esquirol, Zeller, Billod, and Griesinger. The word 'depersonnalisation, derived from a usage in Amiel's Journal intime, was first used in a technical sense by Ludovic Dugas. The new disorder has since been explained as resulting from pathological changes in the sensory system, memory, affect, body image and self-experience. During the 1930s, evolutionary views became popular, particularly in the work of Mayer-Gross. The unclear conceptual boundaries of depersonalization still invite confusion and often enough fragments of what used to be its core-behaviour are used to diagnose the disorder. Depersonalization has of late become subsumed under the dissociative disorders. The definitional instability of the latter, however, has caused further complications to the study of depersonalization. It is recommended that the term is used to refer only to the original core-behaviour as this has shown adequate stability.

Depersonalization↗
PubMed1997

Plasma protein binding of levamisole in several species.

The binding of levamisole to total plasma proteins of 6 animal species was determined in vitro by equilibrium dialysis. The percentage of bound drug protein was independent of levamisole concentration within the range studied, 5-50 micrograms/ml (ANOVA). Levamisole was bound to a low extent to plasma proteins of each animal species (19.40-25.91%). There were significant differences in the extent of levamisole binding among species (ANOVA). Owing to the low degree of protein binding and the high volume of distribution of levamisole, the variations in protein binding due to different factors would not be of major clinical importance in its therapeutic application.

Adjuvants, Immunologic↗
PubMed1996

Organochlorine pesticide residues in bovine milk from Leon (Spain).

Residue levels of the organochlorine pesticides (alpha-HCH, lindane, heptachlor-epoxide, aldrin, endrin, dieldrin, o,p'-TDE, p,p'-TDE, p,p'-DDE and p,p'-DDT) were determined in raw bovine milk and compared with the maximum levels allowed by the European Union (EU) in these foods. The highest incidence percentage of the ten insecticides measured was for lindane, followed by alpha-HCH and aldrin. Moreover, the highest mean residue level was for alpha-HCH. None of the samples analyzed exceeded the maximum levels allowed by the EU.

Animals↗
PubMed1996

Pharmacokinetics of ethinyloestradiol in rabbits after intravenous administration.

The pharmacokinetics of ethinyloestradiol (EE2) after intravenous administration of 30, 50 and 100 micrograms.kg-1 was investigated in rabbits. A high-performance liquid chromatographic (HPLC) method with electrochemical (EC) detection was used to measure EE2 in plasma samples in order to avoid the interferences of natural oestrogens. After compartmental analysis, the disposition of EE2 was well described by a two-compartmental open model with mean values of: alpha = 0.3448 +/- 0.2922, 0.1965 +/- 0.1755, 0.3058 +/- 0.1225 min-1, and beta = 0.0137 +/- 0.0018, 0.0140 +/- 0.0065, 0.0198 +/- 0.0066 min-1, for the three doses studied, respectively. There were no dose-related differences (ANOVA, P < 0.05) in a, b or Vss, but significant differences were detected in clearance (90.9 +/- 18.7; 80.6 +/- 17.6; 116.3 +/- 21.5 ml.min-1.kg-1) between the 100 micrograms.kg-1 group and lower dose groups. The AUC increased significantly with the doses (341.7 +/- 67.1; 645.8 +/- 143.9; 892.2 +/- 211.9 ng.min.ml-1). After non-compartmental analysis there were no significant differences in lambda, MRT or Vss as a function of dose, but these differences were significant when Cl or AUC were compared. There were no significant differences in AUC or Cl values obtained by compartmental and non-compartmental analysis.

Animals↗
PubMed1996

Vasoconstriction of the afferent arteriole and defective renal synthesis of nitric oxide in essential hypertension.

This study was designed to investigate whether some relation exists between afferent arteriolar resistance (AAR) and the renal production of nitric oxide (NO) and prostacyclin (PGI2) in 21 patients with untreated essential hypertension and 20 normotensive controls. All subjects were studied in conditions of an unlimited Na+ diet both basally and after a four-hour amino acid infusion. AAR was calculated using Gomez's equations. Renal production of NO and PGI2 were assessed by radioimmunoassay of the urinary excretion of cGMP and 6-keto-PGF1 alpha, respectively. Baseline AAR was higher (P < 0.01) in hypertensives than in normotensives. The baseline urinary excretion of 6-keto-PGF1 alpha and cGMP were similar in the two groups of subjects. AAR diminished (P < 0.005) in normotensives and remained unchanged in hypertensives after amino acid infusion. Urinary excretion of 6-keto-PGF1 alpha was increased similarly in the two groups of subjects after infusion. Urinary excretion of cGMP remained unchanged in normotensives and decreased by 31% in hypertensives after infusion. These findings suggest that afferent vasoconstriction present in hypertensive patients is unresponsive to the vasodilatory manoeuvre of amino acid infusion. This lack of response may be due to a defective renal synthesis of NO in these patients.

6-Ketoprostaglandin F1 alpha↗
PubMed1995

Numerical taxonomy of an 'atypical' population of gram-positive cocci isolated from freshly dressed lamb carcasses.

One hundred Gram-positive, catalase-positive strains were isolated from freshly dressed lamb carcasses. They were randomly selected from a non-selective medium and tested for 75 characters. Only nine cultures could be identified by conventional methods. A numerical taxonomic study was conducted on the whole population and 25 reference strains. At the 80% similarity level (Ssm), ten clusters were formed. Five of them were entirely composed of reference strains. Phena V and VIII contained seven isolates and two reference strains of Micrococcus. Phena VI (six unidentified isolates), VII (nine staphylococci) and IX (69 unidentified isolates) were more related to M. kristinae than to the remaining reference strains. Properties with possible implications in meat spoilage were: strong lipolytic activity (76%), anaerobic growth (85%), tolerance to 15% (w/v) NaCl (95%) and ability to grow at 15 degrees C (95%) and 4 degrees C (26%).

Animals↗
PubMed1995

[Spontaneous mononucleosis caused by cytomegalovirus in the immunocompetent adult].

BACKGROUND: The first Spanish series of spontaneous infectious mononucleosis (IM) by cytomegalovirus (CMV) in immunocompetent adults is reported. METHODS: Patients whose clinical manifestations, physical exam, analysis and serology were compatible with acute CMV infection from 1984 to 1993 were retrospectively reviewed. RESULTS: Thirty patients with a mean age of 36 years fulfilled the diagnostic criteria. All presented fever, alone or associated with other symptoms, with a mean duration of 18 days, which persisted over 3 weeks in 36%. Physical exam showed lymph node enlargement (50%), hepatomegaly (33%), splenomegaly (20%) and was normal in 8 patients (26%). Mean leukocyte count was 9.75 x 10(9) (+/- 4.63 x 10(9) with more than 50% lymphomonocytic cells in 22 patients (76%) and reactive lymphocytes, principally from the outset, although this was observed on days 2 and 60 in 11 cases (36%). LDH, ASAT and ALAT were moderately elevated and ESR was normal. Serologic diagnosis was established from IgM (13%) seroconversion or positive IgM in the two samples with IgG four-fold increase (23%), as well as the presence of positive IgM and invariable high IgG in both determinations (26%) or all IgM positive titers in a single sample (36%). CONCLUSIONS: Infectious mononucleosis by cytomegalovirus is an infrequently diagnosed disease which should be considered in any young patient with fever despite a little demonstrative initial physical exam absence of atypical lymphocytes or a lack of diagnostic serology.

Adolescent↗
PubMed1994

Effect of three commercial starters on growth of Staphylococcus aureus and enterotoxins (A-D) and thermonuclease production in broth.

The growth of four enterotoxigenic Staphylococcus aureus strains was partially inhibited by three commercial starters used in the meat sausage industry when grown in APT broth at 30 degrees C statically. Starter SP318 (a mixture of selected strains of Lactobacillus sake, Pediococcus pentosaceus and Staphylococcus xylosus) showed the most inhibitory activity. Staphylococcal enterotoxins (A, B, C1 and D) synthesis was totally inhibited by the growth of the three starters, whereas staphylococcal thermonuclease production was partially inhibited in mixed cultures.

Animals↗
PubMed1994

Bioavailability of levamisole administered by subcutaneous and oral routes in rabbits.

The bioavailability of levamisole in rabbits was determined after subcutaneous and oral administration at three dose levels of 12.5, 16.0 and 20.0 mg/kg. After non-compartmental analysis the mean values obtained were: Cmax = 3.54, 4.51 and 5.39 micrograms/ml; tmax = 12.0, 22.0 and 20.0 min; F = 134.8, 105.4 and 124.1% after subcutaneous administration for each dose, respectively, and Cmax = 0.71, 1.32 and 1.77 micrograms/ml; tmax = 46.0, 96.0 and 84.0 min; F = 53.0, 62.0 and 80.7% after oral administration. The extent and rate of absorption from the two routes differed significantly, except for tmax at the 12.5 mg/kg dose. After compartmental analysis the pharmacokinetics of levamisole was characteristic of a two-compartment open model in 13 rabbits and of a one-compartment open model in two rabbits after subcutaneous administration, while it was two compartmental in nine and one compartmental in six rabbits after oral administration. The ka values were 0.321, 0.145 and 0.145 min-1 after subcutaneous administration and 0.054, 0.023 and 0.027 min-1 after oral administration. There were no significant differences between the values of Cmax, tmax and AUC calculated by compartmental and non-compartmental analysis.

Absorption↗
PubMed1993

Rapid high-performance liquid chromatographic assay of ethynyloestradiol in rabbit plasma.

A method for the determination of ethynyloestradiol in samples of rabbit plasma containing pentobarbital and heparin, the former used as an anaesthetic and the latter as an anticoagulant, has been developed. Quantification was carried out using a reversed-phase high-performance liquid chromatographic (HPLC) method in isocratic mode at room temperature, with electrochemical detection at an applied potential of +1 V vs. Ag/AgCl. Under these conditions, the retention time for ethynyloestradiol was ca. 2.9 min, the average recovery from plasma was 74.5%, and the limit of detection was 10 pg, corresponding to a plasma concentration of 50 pg/ml using 1 ml of plasma. Natural oestrogens, oestriol, oestradiol and oestrone showed peaks that did not interfere with ethynyloestradiol, and retention times of ca. 0.8, 2.4 and 3.4 min, respectively.

Animals↗
PubMed1993

Long-term outcome in renal transplantation with terminal cutaneous ureterostomy.

We have reviewed the complications and follow-up in 6 patients who underwent kidney transplantation with cutaneous ureterostomy. Four patients had tuberculosis, 1 myelomeningocele and another congenital stenosis of the posterior urethra. Cutaneous ureterostomy was performed by suturing the edges of the distal end of the ureter to the skin. The mean follow-up was 40.6 months (range 2-105). The patient and graft survival rates were 83.3% and 66.6% respectively during the 249 months of total follow-up. Significant bacteriuria and leukocyturia were constantly present and the incidence of urinary infection was 3.1 episodes/patient/year. The early complications of the stoma were partial necrosis in 1 case and haematoma in another. The most frequent late complication was stomal stenosis requiring periodic dilatation. A plasma creatinine of 61.88 to 114.92 mumol/l reflected good long-term graft function in the remaining patients. Terminal cutaneous ureterostomy is a simple technique with good long-term results.

Adolescent↗
PubMed1992

Pharmacokinetics of levamisole in rabbits after intravenous administration.

A compartmental and non-compartmental pharmacokinetic study was carried out on rabbits after intravenous (i.v.) administration of levamisole at the three dose rates: 12.5, 16.0 and 20.0 mg/kg body weight. Using compartmental analysis, the disposition of levamisole best fitted a two-compartmental open model with mean values of alpha = 0.1278, 0.1019 and 0.1282 min-1; beta = 0.0139, 0.0126 and 0.0124 min-1; A = 6.24, 5.27 and 10.58 micrograms/ml and B = 2.14, 3.83 and 5.08 micrograms/ml for each dose, respectively. The statistical moment theory was mainly used for non-compartmental analysis. Values for mean residence time (MRT) of 69.2, 71.7 and 73.1 min were obtained for each dose. The mean values for volume of distribution at steady state (Vd(ss)), determined by compartmental analysis, were 3879, 3279 and 2735 ml/kg for each dose, and values obtained using the statistical moment theory were 3760, 3015 and 2943 ml/kg; there were no statistically significant differences using Student's paired t-test. Identical conclusions were obtained using both methods when the parameters beta, AUC and Cl were compared.

Animals↗