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Biomedical subjects

R Schaumann

Publications and source records attributed to R Schaumann.

27 records · Page 2Linked to original sources
PubMed1998

Phagocytosis of Escherichia coli and Staphylococcus aureus by neutrophils of human immunodeficiency virus-infected patients.

To study the influence of human immunodeficiency virus (HIV) infection on phagocytosis of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) by polymorphonuclear neutrophils (PMN) from HIV-infected patients in vitro. PMN were isolated from the blood of 25 HIV-infected patients (group 1: CD subset4 </= 250/microL: 14 patients, group 2: CD subset4 >250/microL: 11 patients ) by Percoll density gradient and incubated with E. coli and S. aureus. Subculture technique was used to determine PMN function at 0, 0.5, 1, 2, 4, 6, and 24 hours. Controls were run with PMN from healthy volunteers. Phagocytosis of E.coli and S.aureus by PMN of HIV-infected patients was significantly lower in group 1 (p <0.05). Reduced phagocytosis of E. coli and S. aureus was found in HIV-infected patients with low CD subset4-cell counts. Our findings may contribute to increased susceptibility to bacterial infection in HIV-infected patients with low CD subset4-cell counts.

AIDS-Related Opportunistic Infections↗
PubMed1998

Endothelial cell compatibility of clarithromycin for intravenous use.

OBJECTIVES: Tolerance of intravenously applied clarithromycin has been tested on marginal ear veins of rabbits. Use of human umbilical venous endothelial cells (HUVEC) for testing antibiotic solutions for intravenous compatibility provides a valuable alternate model. DESIGN AND METHODS: In order to evaluate the effect of clarithromycin on intracellular purines, reflecting cell viability, energy production, signal transduction and DNA/RNA synthesis, intracellular adenosine 5' triphosphate (ATP), adenosine 5' diphosphate (ADP), guanosine 5' triphosphate (GTP), and guanosine 5' diphosphate (GDP) levels were measured by means of high performance liquid chromatography (HPLC). RESULTS: Incubation of cells with 2 mg/mL clarithromycin resulted in a rapid decrease of the intracellular ATP from 12.6 +/- 1.1 to 8.87 +/- 0.82 nmol/million cells or 1.5 +/- 0.6 nmol/million cells, after 20 or 60 min, respectively. In addition, ADP was extensively depleted. Purine nucleotide profiles were markedly different following exposure to 1 mg/mL clarithromycin. There was no significant decline of intracellular high energy phosphate levels after 20 min. CONCLUSION: These results show that clarithromycin has a better endothelial compatibility if diluted to a final concentration of 1 mg/mL. These data are in line with our clinical observations that the occurrence of phlebitis could be minimized by diluting the manufacturers' preparation of clarithromycin to 1 mg/mL.

Adenine↗
PubMed1997

Experience with imipenem in internal medicine--a postmarketing surveillance study.

Imipenem was registered for clinical use in Germany in 1985. It is recommended for initial treatment in either severe nosocomial infections or infections in ICU or immunocompromised patients. In this study, we evaluated 1,215 patients who were prescribed imipenem at our Zentrum der Inneren Medizin-a major tertiary care university hospital-over a 6 year period. 650 of 1,215 patients (53.5%) had rapidly fatal disease; and the main indication for imipenem was pneumonia and fever of unknown origin. 56.2% received 500 mg imipenem t.i.d., 40.4% 500 mg b.i.d., 0.9% 1000 mg b.i.d.; and 2.5% 1000 mg t.i.d. Average duration of treatment was 11 days. Lower dose (500 mg b.i.d.) was used in patients with renal insufficiency; highest dose was used in severe infections or infections caused by moderately sensitive organisms. Imipenem was used as a single initial antibacterial agent in the majority of the patients. Success was seen in 80% of the episodes, irrespective of the dosage used; 89% at 500 mg b.i.d., 74% at 500 mg t.i.d., 77% at 1,000 mg b.i.d.; and 69% at 1,000 mg t.i.d. We observed the highest favourable response (91.5%) in the episodes treated initially with imipenem monotherapy. Overall, imipenem was well tolerated. The majority of the patients with untoward effects was on multiple-drug regimens. The most frequent untoward event observed involved the gastrointestinal tract.

Adult↗
PubMed1997

Endothelial cell compatibility of fluoroquinolone solutions for intravenous use.

One local side-effect closely related to the use of parenteral fluoroquinolones is phlebitis. The occurrence of this phenomenon is largely thought due to the damage of endothelial cells with subsequent inflammation. In order to evaluate the effect of ciprofloxacin, fleroxacin, and ofloxacin on the viability of human umbilical venous endothelial cells (HUVEC), intracellular ATP levels were measured by a luciferin-luciferase assay. Prostacyclin (PGI2) and thromboxane A2 (TXA2) were determined by means of direct radioimmunoassay. Commercially available preparations of ciprofloxacin (2 mg/ml) and fleroxacin (4 mg/ml) reduced the intracellular ATP content by 75.9 +/- 1.9% and 82.1 +/- 0.6%, respectively, within 20 minutes, indicating severe damage of endothelial cells. Incubation with ofloxacin (2 mg/ml) did not have any detrimental effect. All fluoroquinolones were tolerated well by endothelial cells at low concentrations up to 20 micrograms/ml. Concentrations between 100-200 micrograms/ml gradually led to functional alterations such as increased PGI2 release. The tolerance of intravenously applied antibiotics has been tested in animal models. Use of human venous endothelial cells for testing antibiotic solutions for intravenous application provides a valuable alternate model for tolerability.

6-Ketoprostaglandin F1 alpha↗
PubMed1995

Influence of free or liposomal amphotericin B on killing of Candida species by human peritoneal macrophages.

The influence of free and liposomal amphotericin B at subinhibitory and inhibitory concentrations on killing of Candida albicans (ATCC 10231), Candida tropicalis (ATCC 13803) and Cryptococcus neoformans (930) by human peritoneal macrophages was investigated in vitro. Peritoneal macrophages were harvested from overnight peritoneal dialysate of 10 patients undergoing regular continuous ambulatory peritoneal dialysis and incubated with Candida species (1:2), pooled human serum, fetal calf serum, Medium 199 and Sabouraud broth (with or without amphotericin B) for 6 hours. The killing of Candida species was determined using subculture technique. The combination of amphotericin B (free or liposomal) with peritoneal macrophages enhanced the killing of the Candida species. Candidacidal activity of free and liposomal amphotericin B resulted in comparable effects; however, the killing of the yeasts by liposomal amphotericin B was slower than by free amphotericin B.

Adult↗
PubMedDate not supplied

Empirical monotherapy with meropenem versus imipenem/cilastatin for febrile episodes in neutropenic patients.

In a nonblind, randomised, parallel-group study, initial empirical monotherapy with meropenem 1 g intravenously every 8 h was compared to an identical dosage of imipenem/cilastatin for the treatment of 66 febrile episodes in 61 adult neutropenic patients. 25/31 episodes treated with meropenem and 24/30 imipenem/cilastatin-treated episodes were still receiving unmodified therapy at 72 h (primary endpoint); this difference was not statistically significant. By the end of the treatment courses, 18/31 meropenem-treated episodes had responded clinically (cured or improved) compared with 18/30 episodes treated with imipenem/cilastatin. Another ten episodes initially treated with meropenem and six episodes treated with imipenem/cilastatia were cured after an additional antimicrobial agent had been administered (cured with modification). Satisfactory bacteriological responses (eradication plus presumed eradication) at the end of unmodified therapy was 9/11 in the meropenem group and 14/16 in the comparator group. Both regimes were well tolerated; however, there were more reports of nausea and/or vomiting in the impenem/cilastatin group (7/33 vs. 2/33 in the meropenem group). The carbapenems meropenem and imipenem/cilastatin appear to be suitable agents for empirical monotherapy of febrile episodes in neutropenic patients. Meropenem may be better tolerated than imipenem/cilastatin, allowing optimal dosing in this patient population.

Adult↗
PubMedDate not supplied

Pericarditis after allogeneic peripheral blood stem cell transplantation caused by Legionella pneumophila (non-serogroup 1).

A case of Legionella pericarditis caused by a Legionella pneumophila isolate other than serogroup 1 is reported in a 59-year-old man after allogeneic peripheral blood stem cell transplantation. On admission a 5 mm pericardial effusion was detected on echocardiography. Antibodies were detected against L. pneumophila serogroups 7 to 14 using the antigen pool and against serogroup 12 alone. Antibodies were not detected against the serogroup 1 to 6 antigen pool. The patient's clinical condition improved dramatically after treatment with clarithromycin and an echocardiography revealed the total disappearance of the pericardial effusion.

Anti-Bacterial Agents↗