Population Pharmacokinetics of Unbound and Total Teicoplanin in Critically Ill Pediatric Patients.

BACKGROUND AND OBJECTIVES: Teicoplanin is a highly protein-bound antibiotic, increasingly used to treat serious Gram-positive infections in critically ill children. Maturational and pathophysiological intensive care unit-related changes often lead to altered pharmacokinetics. In this study, the objectives were to develop a pediatric population-pharmacokinetic model of unbound and total teicoplanin concentrations, to investigate the impact of plasma albumin levels and renal function on teicoplanin pharmacokinetics, and to evaluate the efficacy of the current weight-based dosing regimen. METHODS: An observational pharmacokinetic study was performed and blood samples were collected for quantification of unbound and total concentrations of teicoplanin after the first dose and in assumed steady-state conditions. A population-pharmacokinetic analysis was conducted using a standard sequential approach and Monte Carlo simulations were performed for a probability of target attainment analysis using previously published pharmacokinetic-pharmacodynamic targets. RESULTS: A two-compartment model with allometric scaling of pharmacokinetic parameters and non-linear plasma protein binding best described the data. Neither the inclusion of albumin nor the renal function significantly improved the model and no other covariates were supported for inclusion in the final model. The probability of target attainment analysis showed that the standard dosing regimen does not satisfactory attain the majority of the proposed targets. CONCLUSIONS: We successfully characterized the pharmacokinetics of unbound and total teicoplanin in critically ill pediatric patients. The highly variable unbound fraction of teicoplanin could not be predicted using albumin levels, which may support the use of therapeutic drug monitoring of unbound concentrations. Poor target attainment was shown for the most commonly used dosing regimen, regardless of the pharmacokinetic-pharmacodynamic target evaluated.

Massive pneumomediastinum with subcutaneous emphysema after elective adenotonsillectomy in children: Involvement of the Boyle-Davis mouth gag.

Adenotonsillectomy, a very common surgical procedure in otorhinolaryngology, is considered easy and safe surgery. However, clinicians should be aware of some less common but potentially life-threatening complications. This report discusses subcutaneous emphysema with pneumomediastinum following elective adenotonsillar surgery in children. The Boyle-Davis mouth gag seemed to play a part in the pathogenic mechanism of this rare complication in this case. Better insights in the mechanism of this severe complication of adenotonsillectomy may contribute to the prevention of this complication.

Lactate dehydrogenase isoenzyme pattern: marker for differentiation of lymphocytes.

The lactate dehydrogenase isoenzyme pattern has been determined in different murine thymocyte cell populations. Enrichment of thymocytes with more mature cells through total irradiation results in a smaller percentage of LDH-1, LDH-2, LDH-3 and a greater percentage of LDH-4 and LDH-5. Fractionation of normal thymocytes by velocity sedimentation at unit gravity yields a fraction of cells with a high sedimentation rate. LDH-1 and LDH-2 formed a smaller percentage of the total enzyme activity in these cells. These findings indicate that the LDH isoenzyme distribution is a marker for differentiation of thymocytes.

Study of messenger-like RNA extracted from HeLa cells polysomes. II. Identification of the types of RNA eluted from methylated albumin kieselguhr columns.

Together with the elution pattern of pure messenger RNA molecules of various origin, the labelling kinetics of rapidly labelled heterogeneously sedimenting RNA (HSRNA) extracted from polysomes of HeLa cells have been studied by chromatogrphy on columns made of methylated bovine serum albumin adsorbed on kieselguhr. HSRNA is eluted within three peaks-IP, Q2P and TDP-following in that order the increase of NaC1 concentration in the eluting buffer. Besides peak TDP which results from an experimental artefact, our data suggest that the appearance of peaks IP and Q2P reflects the absence and presence respectively of polyadenylic acid stretches in these molecules. Within peak Q2P, the critical factor affecting the order of elution is the size of the polyadenylic acid stretch.

Influence of nandrolone decanoate on the repopulation of the thymus after total body irradiation of mice.

It has been reported that nandrolone decanoate is helpful in overcoming the neutropenic phase following irradiation. In the present study the influence of nandrolone decanoate on the thymus' cellularity after total body irradiation was investigated. In comparison with a placebo-treated group, mice receiving nandrolone decanoate showed a similar pattern of thymus repopulation, but a significantly lower number of thymocytes over the whole period of treatment was found. Nonirradiated mice also had a significantly lower number of thymocytes when treated with nandrolone decanoate. In addition, the number of circulating leukocytes was also evaluated over a period of 1 month after total body irradiation. On 11 of the 21 days investigated, a significantly higher number of leukocytes was found in the nandrolone decanoate-treated group. We conclude that the action of nandrolone decanoate was not clearly distinct from that of testosterone regarding either granulopoiesis or thymic involution.

A monoclonal antibody directed against a human cell membrane antigen prevents cell substrate adhesion and tumor invasion.

It was the aim of this study to design mouse monoclonal antibodies (MAbs) that can inhibit the invasion of breast cancer cells in the host tissue. Therefore, MAbs were raised against epitopes on the extracellular domain of SK-BR-3 human breast cancer cells, and biological assays were performed to test the capability of the MAbs to inhibit cell substrate adhesion. MAb 14C5 bound an extracellular plasma membrane antigen of SK-BR-3 and MCF-7 human breast cancer cells and inhibited the cell substrate adhesion of these cells in vitro. The MAb delayed the adhesion of MCF-7 and SK-BR-3 cells on precultured embryonic heart fragments (PHFS). It inhibited the destruction of the PHF by MCF-7 cells and the invasion of the PHF by SK-BR-3 cells. The MAb reacted with an epitope on the cell membrane of in situ and invasive ductal carcinomas of the breast in immunohistochemistry. Poorly differentiated, highly invasive ductal carcinomas show extensive staining of long plasma membrane extensions. Normal multilayered epithelia, normal connective tissue, and tumors derived from these tissues as well as normal breast tissue were negative. From both cell lines a protein complex consisting of two subunits with molecular weight of 50 and 90 kd, respectively, was immunoprecipitated. It is concluded that the 14C5 antigen plays a role in cell substrate adhesion and subsequently also in invasion of breast cancer cells. The 14C5 MAb was able to inhibit cell substrate adhesion and invasion in vitro of breast cancer cells.