Boban M. Erovic

Distribution and Antimicrobial Activity of Fosfomycin in the Interstitial Fluid of Human Soft Tissues

ABSTRACT Fosfomycin is a broad-spectrum antibiotic which is established as therapy for uncomplicated lower urinary tract infections. In addition, preliminary data indicate that fosfomycin has a potential role in the treatment of soft tissue infections. However, the use of fosfomycin has not been established for this condition, and it is unclear whether the level of fosfomycin penetration into human soft tissues is high enough to eradicate relevant pathogens. To better characterize the antibiotic potential of fosfomycin, we applied a combined in vivo pharmacokinetic-in vitro pharmacodynamic model to human volunteers. For this purpose fosfomycin concentrations in vivo in the fluid of the interstitial space of human soft tissues were measured by microdialysis following intravenous infusion of 4 or 8 g of fosfomycin (n = 6). Subsequently, bacterial isolates with relevance for soft tissue infections were exposed to concentrations according to the in vivo pharmacokinetic profile in the interstitial space fluid obtained by microdialysis. Our experiments indicated a high degree of soft tissue penetration for fosfomycin, with ratios of the area under the concentration-time curve from 0 to 8 h for muscle (AUC0–8muscle)/AUC0–8serumof 0.48 ± 0.08 and 0.53 ± 0.04 and ratios of AUC0–8adipose tissue/AUC0–8serum of 0.74 ± 0.12 and 0.71 ± 0.11 following administration of 4 and 8 g, respectively. In corresponding in vitro simulation experiments with selected isolates of Staphylococcus aureus,Enterobacter cloacae, and Serratia marcescensfor which MICs were 16 μg/ml, organisms were undetectable after a single dosing interval. Fosfomycin exhibits a strong ability to penetrate into the fluid of the interstitial space of soft tissues and reaches levels sufficient to substantially inhibit the growth of relevant bacteria at the target site. We therefore conclude that fosfomycin might qualify as an alternative candidate for the therapy of soft tissue infections.

Vascular endothelial growth factor receptor 2 (VEGFR2) expression in squamous cell carcinomas of the head and neck

Objectives Vascular endothelial growth factor receptor 2 (VEGFR2; Flk‐1 [fetal liver kinase]/KDR [kinase insert domain containing receptor]) has been identified as a high affinity receptor for vascular endothelial growth factor (VEGF) on vascular endothelium. Head and neck squamous cell carcinomas (HNSCC) have already been shown to produce substantial amounts of VEGF. VEGFR2 is supposed to play a major role in tumor‐neoangiogenesis.

Target Site Concentrations of Ciprofloxacin after Single Intravenous and Oral Doses

ABSTRACT To characterize the potential of ciprofloxacin penetration into human soft tissues following intravenous (i.v.) and oral (p.o.) administration, we measured the free ciprofloxacin concentrations in interstitial space fluid of skeletal muscle and subcutaneous adipose tissue by microdialysis. In addition, ciprofloxacin concentrations were measured in cantharis-induced skin blisters, saliva, and capillary plasma and were compared to the total concentrations in venous plasma. Furthermore, a pharmacodynamic in vitro model was used to simulate in vivo pharmacokinetics in bacterial culture. Eight healthy volunteers received ciprofloxacin in an open randomized crossover fashion either as a single i.v. infusion of 400 mg over 60 min or as a single p.o. dose of 500 mg. For both tissues the mean areas under the concentration-time curves (AUCs) for interstitial space fluid (AUCinterstitial fluids) were significantly lower than the corresponding AUCplasmas, with AUCinterstitial fluid/AUCplasma ratios ranging from 0.38 to 0.68. For skeletal muscle, the AUCinterstitial fluid was significantly higher after administration of 400 mg i.v. than after administration of 500 mg p.o., with a ratio of the AUC after p.o. administration/AUC after i.v. administration of 0.64. The ratio of the concentration in skeletal muscle/concentration in plasma increased over the entire observation period, implying that ciprofloxacin concentrations were not at steady state. The ratio of the concentration in skin blister fluid/concentration in plasma reached values above 4, indicating a preferential penetration of ciprofloxacin into inflamed lesions. The concentrations in saliva and capillary blood were similar to the corresponding total levels in plasma. In vitro both in vivo ciprofloxacin concentration-time profiles were equally effective against select bacterial strains. In conclusion, single-dose administration of two bioequivalent dosage forms of ciprofloxacin might lead to differences in target site pharmacokinetics. These differences, however, are not related to a difference in target site pharmacodynamics.

Target site concentrations after continuous infusion and bolus injection of cefpirome to healthy volunteers

Recent data indicate a higher level of effectivity of β‐lactam antibiotics if serum concentrations are kept above the minimal inhibitory concentration (MIC) of the pathogen. This concept would favor continuous infusion over bolus dosing. However, it is usually not the serum concentration but the free interstitial concentration in the target tissue that determines antibiotic activity. We therefore set out to measure effective drug concentrations in the interstitial space of muscle and subcutaneous adipose tissue and to compare trough levels and times above the MIC after bolus versus continuous infusion of cefpirome.

Motility-related protein-1/CD9 expression in head and neck squamous cell carcinoma

Motility‐related protein (MRP)‐1/CD9 is implicated in cell adhesion and motility and was shown to be clearly involved in tumor prognosis and angiogenesis. Elevated MRP‐1/CD9 expression on tumor cells has been linked to a favorable prognosis in breast cancer, colon cancer, lung cancer, and HNSCC. Because MRP‐1/CD9 is associated with angiogenesis, it might play a role in tumor angiogenesis as well.

CD9 Expression on Lymphatic Vessels in Head and Neck Mucosa

CD9, a member of the transmembrane 4 superfamily, is involved in cell adhesion, migration, and tumor metastasis. Little is known about its vascular expression pattern. In this study, we investigated CD9 expression on endothelial cells in the mucosa of the head and neck and compared it with vascular tumors. Using immunohistochemistry, expression of CD9 was studied in 17 samples of head and neck mucosa and skin (laryngeal mucosa: n = 2, oral: n = 6, and epidermis: n = 9) and a variety of vascular tumors (lymphangiomas: n = 9, juvenile nasopharyngeal angiofibromas: n = 4, hemangiomas: n = 7, angiosarcomas: n = 5, and Kaposis sarcomas: n = 7) and compared with the expression of CD34 and PAL-E (blood vessel markers) and the lymphatic marker podoplanin. Regular lymphatic endothelium and lymphangiomas were strongly positive for CD9 and podoplanin but were mostly negative for PAL-E and CD34. By contrast, blood vessel endothelium and hemangiomas were strongly positive for PAL-E and CD34 but were mostly negative for CD9 and podoplanin. Weak to moderate CD9 reactivity was also observed on EC of juvenile nasopharyngeal angiofibromas, angiosarcomas, and Kaposis sarcomas. Expression of CD9 by lymphatic EC was confirmed by reverse-transcriptase PCR and Western blot analyses. CD9 may be useful as a marker for lymphatic EC. It could promote the adherence of inflammatory and tumor cells to lymphatic EC and participate in the growth and maintenance of the lymphatic capillary net.

Quantitation of microvessel density in squamous cell carcinoma of the head and neck by computer-aided image analysis

SummaryOBJECTIVE: Angiogenesis is the formation of new blood vessels from a preexisting vascular network. In healthy individuals it is normally suppressed and observed only transiently during development, reproduction and wound healing. However, growth, invasion, and metastasis of most solid tumors are dependent on angiogenesis. Without formation of new blood vessels, also termed as neovascularization, tumors cannot exceed a size of about 1 mm3. Therefore, neovascularization is a basic requirement for nutrition and oxygenation of tumor cells. Numerous studies in different solid as well as non-solid tumors have evaluated the prognostic value of tumor neovascularization. In solid tumors the increased microvessel density, the pathological correlate to tumor neovascularization, has been linked to a worse prognosis of the disease. The aim of the current study was to assess the prognostic value of tumor neovascularization for recurrences in squamous cell carcinoma of the head and neck by determining microvessel density. Data was collected using an automated-computerized method and as well as a manual counting method. BASIC RESEARCH DESIGN: Immunohistochemistry was performed to detect intratumoral microvessels in tumor samples of 50 patients with squamous cell carcinoma of the head and neck. We used a monoclonal mouse antibody directed against the CD34 antigen. After immunostaining, the entire tumor section was scanned microscopically at low power (×40) to identify hot spots, which are the areas of highest neovascularization. Individual tumor microvessels were then counted under high power (×200) to obtain a vessel count in a defined area, and the average vessel count in 4 hot spots was taken as the microvessel density. Microvessel counting was performed twice by computerized method, as well as manually by two independent investigators without any previous knowledge of patients’ pertinent clinical data. Subsequently, both counting techniques were statistically compared with each other. RESULTS: On computer-aided image analysis an increased microvessel density was significantly correlated with recurrence of disease (p = 0.02). Repetitive computer counts yielded similar results (p = 0.08), whereas repeated manual counts by two investigators varied significantly (p = 0.04). However, no further statistical correlations between microvessel density and patients clinical data i.e. tumor status, lymph node status, overall survival, or disease free interval could be found. Furthermore, estimation of overall survival of patients with an increased microvessel density by Kaplan–Meier curves revealed non-significant results. CONCLUSION: There is mounting evidence that suggests, that assessment of tumor neovascularization might provide a novel approach of prognostication in patients with squamous cell carcinomas of the head and neck. In particular, in the present study, the degree of angiogenesis of a tumor, as assessed by microvessel density, was found to be correlated with recurrent disease in squamous cell carcinoma of the head and neck. Computer aided image analysis, an automated technique, constitutes a time-efficient and reproducible technique for quantification of tumor vascularization. We suggest that this computerized microvessel determination could be used as a reliable method for microvessel counts, which, furthermore, seems to be superior to manual counting. However, for a reliable and reproducible assessment of tumor neovascularization, validation procedures and quality control protocols are mandatory.

Validation of urea as an endogenous reference compound for the in vivo calibration of microdialysis probes.

Microdialysis is a widely used experimental technique, which offers the opportunity to measure drug and metabolite concentrations in the interstitial space fluid in animals and humans. However, microdialysis probes need to be calibrated in vivo to obtain a recovery factor, which describes the relative drug transfer across the membrane. Recently, novel time-saving calibration techniques, based on the use of reference compounds, have been developed. In particular, the use of endogenous urea levels has been advocated. In the present study we set out to validate the use of the urea reference technique for microdialysis probe calibration in healthy volunteers, employing glucose and paracetamol as model analytes. Urea calibration was compared with the results of two standard calibration techniques, i.e. the no net flux technique and the retrodialysis technique. For glucose, recovery values, calculated by the urea reference technique differed significantly from those values, which were assessed by the no net flux technique (p < 0.05), whereas for paracetamol recovery values did not differ significantly, albeit a high intramethod variability was observed (CV=66%). As a conclusion, we could not confirm the hypothesis that recovery values calculated by the urea reference technique provide equivalent results compared with standard calibration techniques.

Differential Expression Pattern of Cyclooxygenase-1 and -2 in Head and Neck Squamous Cell Carcinoma

Objective—The enzyme cyclooxygenase catalyzes the first step of the synthesis of prostanoids. Cyclooxygenase has been shown to exist in two distinct isoforms: cyclooxygenase-1 is constitutively expressed as a housekeeping enzyme in most tissues whereas the inducible cyclooxygenase-2 has been reported to be involved in inflammatory processes and in the carcinogenesis of squamous cell carcinoma. The aim of this study was to investigate the distribution patterns of cyclooxygenase-1 and -2 in peritumoral lymphocytic infiltrates and tumor cells of head and neck carcinoma. Material and Methods—Immunohistochemical analysis was performed using paraffin-embedded tumor specimens from 24 patients suffering from oropharyngeal, hypopharyngeal and oral squamous cell carcinomas. Results—We observed that cyclooxygenase-2 immunoreactivity, compared to that of cyclooxygenase-1, was significantly increased in peritumoral lymphocytic infiltrates as well as in tumor cells. Conclusion—The expression of cyclooxygenase-2 in both tumor specimens and the surrounding peritumoral lymphocytic infiltrates supports the hypothesis that cyclooxygenase may be one of several important links between chronic inflammation and carcinogenesis.

Formveränderung und Trauma von Nase und Ohr Nasenpframidenfraktur

geschlossene oder offene Fraktur der Nasenbeine unter eventueller Mitbeteiligung des Nasenseptums isoliertes Vorkommen (haufig) oder in Kombination mit einer Mittelgesichtsfraktur direkte Gewalteinwirkung: Sportverletzung, Raufhandel etc.