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Biomedical subjects

K Strobel

Publications and source records attributed to K Strobel.

At least 19 recordsLinked to original sources
PubMed2006

18F FDG-PET imaging in musculoskeletal infection.

(18)F Fluorodeoxyglucose-positron emission tomography (FDG-PET) has become an encouraging imaging modality in musculoskeletal infection. This application has an incremental value in the assessment of both acute and chronic infection and has shown to be more accurate in detecting chronic osteomyelitis than conventional radionuclide imaging. Whether FDG-PET has the potential to replace conventional scintigraphy completely depends on a number of factors, including cost and availability. Conventional radionuclide studies have represented imaging methods of choice in the diagnosis of implant-associated infection in patients with trauma so far. However, nonspecific tissue uptake of imaging agents and limited spatial resolution restrict their usefulness. Magnetic resonance imaging (MRI) and computed tomography (CT) image quality is degraded in the presence of metallic implants due to susceptibility and beam-hardening artifacts, respectively. Although its role is still evolving, FDG-PET imaging will have increased importance in patients with metallic implants used for trauma surgery because FDG uptake is not hampered by metallic artifacts. In contrast to patients with metallic implants, PET may not be as useful in the diagnosis of infection in patients with failed total joint replacements. In this situation, combined 111Indium-labeled leucocyte/(99m)Tc-sulfur colloid marrow imaging still remains the gold standard. This article reviews the currently available literature on FDG-PET and PET/CT in the diagnosis of musculoskeletal infection.

Clinical Trials as Topic↗
PubMed2005

How much intravenous contrast is needed in FDG-PET/CT?

Intravenous, iodinated contrast agents are used routinely for CT (ceCT) imaging but only applied reluctantly for FDG-PET/CT due to possible artefacts. Only for few oncological PET/CT indications, the role of IV contrast agent has been clarified. Essentially, if any knowledge regarding vascular structures or tumour invasion into adjacent structures are needed, a ceCT as part of the combined PET/CT exam should be implemented. However, for some indications like lymphoma, contrast seems not to be necessary. Therefore, imaging procedures for the use of IV contrast for PET/CT have to be adapted individually for each FDG-PET/CT indication to especially reduce unnecessary radiation burden to the patient.

Contrast Media↗
PubMed2002

[Crohn's disease and stromal sarcoma of the small bowel--a rare coincidence].

We report the case of a 29-year-old female who suffers for more than 13 years from Crohn's disease. A small bowel resection had to be performed because of a complicated and insufficiently controlled course of the disease with beginning subileus. At laparotomy a leiomyosarcoma was found. This case represents the forth case in the literature of an association between chronic inflammatory bowel disease and malign mesenchymal tumors. Tumors of epithelial and lymphoreticular origin are known as a much more common complication in Crohn's disease and especially ulcerative colitis. An exact histological characterization of these sarcomas is important to define the prognosis of the disease. If recurrent subileus is poorly controlled in Crohn's disease stromal tumors with their frequent intraluminal growth have to be considered as part of the differential diagnosis.

Adult↗
PubMed2000

Endoscopic ultrasound criteria for vascular invasion in the staging of cancer of the head of the pancreas: a blind reevaluation of videotapes.

BACKGROUND: It has been claimed in several prospective studies that endoscopic ultrasonography (EUS) is highly accurate in the locoregional staging of pancreatic cancer. However, the value of the EUS criteria for the diagnosis of vascular involvement is less well established. To totally exclude potential bias introduced by the availability of prior information, a completely blinded analysis of videotapes of patients with cancer of the pancreatic head was therefore conducted. METHODS: Videotape sequences of 75 patients with cancer of the head of the pancreas with surgical confirmation or unequivocally positive angiography demonstrating vascular invasion were reevaluated without any clinical data or information from other imaging studies. Involvement of the vascular system (portal vein with confluence, superior mesenteric vein, celiac axis) was assessed on EUS with special emphasis on EUS parameters of the tumor-vessel relationship. RESULTS: The overall sensitivity and specificity of EUS in the diagnosis of venous invasion were 43% and 91%, respectively, when using predetermined parameters (visualization of tumor in the lumen, complete obstruction, or collateral vessels). If the parameter "irregular tumor-vessel relationship" had been added to these criteria, the sensitivity would have risen to 62%, but the specificity would have fallen to 79%. The only vascular system that could be properly visualized by EUS was the portal vein/confluence area. The positive and negative predictive values for the single parameters chosen to diagnose portal venous involvement were as follows: 42% and 33% for irregular tumor-vessel relationship, 36% and 34% for visualization of tumor in the vascular lumen, 80% and 28% for complete vascular obstruction, and 88% and 18% for collateral vessels. CONCLUSIONS: In a completely blinded evaluation of the EUS diagnosis of vascular invasion by cancer of the head of the pancreas it was not possible to find suitable morphologic parameters with clinically useful sensitivity and specificity values (over 80%).

Adult↗
PubMed1998

[Blood tests for PCB in teachers at a heavily PCB-polluted school].

The levels of PCB 28, 52, 101, 153, 138 and 180 were determined in blood samples of subjects (mainly teachers; n = 18) who had worked in a PCB-contaminated school-building for many years (average: 14.2 years). The PCB concentrations in indoor air ranged up to 13,500 ng/m3. For comparison PCB blood levels were determined in 18 teachers working in schools not contaminated by PCB. The subjects of the reference group were matched with the exposed subjects with respect to age and gender. PCB 28, 52 and 101 were not detectable in the blood samples (detection limit: 0.1 microgram/l). In the exposed subjects blood levels of PCB 153 and 138 were, on average, slightly higher and the levels of PCB 180 slightly lower when compared with the reference subjects, but the differences were not statistically significant. The levels of PCB 153, 138 and 180 increased with age. With the exception of two subjects the levels of these congeners were below the reference values proposed by Kappos et al. The results show that inhalative exposure to PCB 153, 138 and 180 is very low in comparison to PCB background exposure via food. Due to rapid metabolisation and elimination the blood levels of PCB 28, 52 and 101 are usually very low.

Adult↗
PubMed1990

Bioavailability and pharmacokinetics of rectally administered metoclopramide.

The absolute and relative bioavailability of metoclopramide following the administration of a single suppository--test (Gastrosil) and reference preparations--containing 20 mg of the pure drug or after i.v. injection of 17.8 mg was compared in 12 sex matched healthy volunteers according to an open, three-way cross-over, intra-individual design. The metoclopramide plasma levels were determined up to 32 h following rectal administration and 24 h following intravenous application using a modified and specific HPLC-assay. The areas under the concentration-time curves were either calculated to the last time-interval measured (AUC-1) by using the trapezoidal rule or by extrapolating to infinity (AUC(0-infinity] in a model-dependent manner. Pair-differences and ratios were taken for the individual AUC-values and for the maximum plasma levels (cmax-values) at the corresponding time values (tmax-values) for test and reference formulations and tested for statistical significance. The results showed the mean AUC-1 and AUC (0-infinity)-values respectively to be 10.7% and 9.5% lower for the test suppository. The mean tmax-values were found to be 21% and 11.6% lower and the mean cmax-values were found to be about 4.3% larger than the corresponding parameters for the reference formulation. The 95% Wilcoxon confidence limits for both test and reference preparation were found to range from 80.2-108.9% for all AUC-values and to lie in the region 83.5-120.3% and 57.8-100% for the cmax- and tmax-values, respectively. Thus, with respect to the pharmacokinetic target parameters, little difference can be found between the two suppository forms each containing 20 mg metoclopramide-base and under trial in this study.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Rectal↗
PubMed1987

Pharmacokinetics and dose recommendations of carumonam in renal failure.

The pharmacokinetics of (Z)-[[[(2-aminothiazol-4-yl)[[(2S,3S)-2-(hydroxymethyl)-4-oxo-1- sulfoazetidin-3-yl]carbamoyl]methylene]amino]oxo]acetic acid, disodium salt (carumonam, Ro 17-2301) after a 2 g intravenous infusion (20 min) were evaluated in 10 healthy volunteers and 20 patients with various degrees of renal failure. The main results of the kinetic parameters in healthy volunteers (mean + SD) corrected for zero infusion time and 70 kg body weight were: t1/2 alpha, 29 +/- 12 min; t1/2 beta, 108 +/- 27 min; AUCtot, 327 +/- 40 mg h/l; Vdss, 12.2 +/- 1.5 l/70 kg; urinary recovery, 78.7 +/- 8.2%; total clearance 103 +/- 13 ml/min; renal clearance, 85 +/- 13 ml/min. Because of the large variation in the degree of renal insufficiency, calculations of the mean values for the pharmacokinetic parameters in the patient group were not generally justified with the exception of the volume of distribution (Vdss = 14.4 +/- 3.0 l/70 kg). To derive dose recommendations, a regression analysis was performed using values from both the volunteer and patient group for the total area under curve (AUCtot) and glomerular filtration rate (GFR), divided by the mean AUCtot value for the volunteers. This curve can be interpreted as giving the dose reduction factor (DRF) as a function of GFR, where by definition, DRF = 1 for healthy (and young) subjects. Using this method of equivalent areas, no (or only a slight) dose reduction is necessary for patients with GFR values above 40 ml/min.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

[Pharmacokinetic studies and bioavailability of bendroflumethiazide in combination with spironolactone].

An intraindividual comparative multiple-dose study (6 days) was carried out under controlled conditions on 10 healthy volunteers in order to establish the bioavailability of bendroflumethiazide (Bft; 3-benzyl-6-trifluoromethyl-7-sulfamyl-3,4-dihydro-1,2,4-benzoth iad iazine-1, 1-oxide), the sum of the fluorogenic metabolites of spironolactone (3-[3-oxo-7-alpha-acetylthio-17 beta-hydroxy-4-androstene-17-alpha-yl]-propionic acid-gamma-lactone) and canrenone, the main spironolactone metabolite from a fixed combination of Bft with spironolactone vs. the commercial preparations of the single drugs. Canrenone was assayed from plasma by high-performance liquid chromatography (HPLC) whereas Bft and the total aldosterone antagonistically acting spironolactone metabolites were determined fluorometrically. Both the fixed and the monosubstance formulation can be considered as bioequivalent for canrenone and the total fluorescence. Bft, in contrast, shows a reduced systemic availability of 61% when administered as the single drug formulation. A 2-compartment model was taken as the basis for the calculation of the steady-state plasma concentration curves and the pharmacokinetic parameters of Bft, canrenone and the sum of the fluorogenic spironolactone metabolites. Following oral multiple administration of 2.5 mg Bft (b.i.d.), the terminal elimination half-life, the steady-state volume of distribution and the total plasma clearance were determined to be 8.6-8.2 h, 0.88 l/kg and 269.4 ml/min, resp. In contrast to Bft, the AUC(120,tlast)-values for post-steady-state elimination, starting with the final spironolactone dose on day 6 were comparable.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1986

Pharmacokinetics and bioequivalence of different formulations of pirenzepine.

An intraindividual comparative single-dose study was carried out under carefully controlled conditions on 12 healthy volunteers in order to establish the bioavailability of 5,11-dihydro-11-[(4-methyl-piperazin-1- -yl)acetyl]-6H-pyrido[2,3b][1,4]benzodiazepin-6-one dihydrochloride (pirenzepine), the active principle of newly developed tablets (Gastricur) and suspension containing 10 mg. In an additional multiple dose, cross-over study on 12 healthy volunteers, the bioequivalence of pirenzepine was investigated after administration of the newly developed vs. commercial dose-equivalent tablets. Pirenzepine was assayed from plasma by a new, highly sensitive high-performance liquid chromatography method. A 3-compartment model was taken as a basis for the calculation of the plasma concentration curves and the pharmacokinetic parameters. Following i.v. administration, the terminal elimination half-life, t 1/2, the volume of distribution, V1, and the total plasma clearance Cl were determined to be 7.7 +/- 1.4 h, 0.255 +/- 0.057 l/kg and 263.4 +/- 56.8 ml/min, respectively. From the tablet and suspension formulation the systemic availabilities were calculated to be 33.5% and 20.3%, respectively. In the multiple dose study, both tablet forms investigated were bioequivalent.

Administration, Oral↗
PubMed1985

[The pharmacokinetics and bioequivalence of various dosage forms of ambroxol].

An intraindividual comparative single-dose study was carried out under carefully controlled conditions on 12 healthy volunteers in order to establish the bioavailability of trans-4-(2-amino-3,5-dibromobenzyl)-amino-cyclohexanol (ambroxol) the active principle of newly developed tablets and drops, in comparison to a commercial i.v. preparation. In an additional single-dose, cross-over study on 12 healthy volunteers the bioequivalence of ambroxol was investigated after administration of a newly developed vs. a commercial dose-equivalent, sustained-release dosage form. Following off-line derivatisation using formaldehyde to the corresponding tetrahydroquinazoline compound, ambroxol was assayed from plasma by high-performance liquid chromatography. A 2-compartment model was taken as a basis for the calculation of the plasma concentration curves and the pharmacokinetic parameters following intravenous injection of the drug. After i.v. administration, the terminal elimination half-life, the apparent volume of distribution and the total plasma clearance were determined to be 3.72 h, 1.52 l/kg and 565 ml/min, respectively. From the tablet and drop formulations the systemic availabilities were calculated to 73 and 81%, respectively; the mean transit times were determined to be 6.8 and 5.4 h, respectively. Both sustained-release dosage forms investigated are bioequivalent.

Adult↗
PubMed1983

Distribution of oxametacine and its anti-inflammatory metabolites in inflamed tissues of rats.

The anti-inflammatory drug oxametacine (1-p-chlorobenzoyl-5-methoxy-2-methyl-3-indolylacetohydroxamic acid) is extensively metabolized both in laboratory animals and in man. In rats, dosed orally with 5 mg/kg [14C]-oxametacine, there is a 2.2-2.7 fold increase in radioactivity in the inflamed tissues, in the hind-paws of animals with adjuvant arthritis and in the granulomas of cotton-pellet implanted rats. The total tissue radioactivity (following two-fold extraction with methanol; recoveries being 95 +/- 3%) was distributed into the following metabolites: 34-7% oxametacine, 26-37% indomethacin, 16-46% demethylindomethacinamide, and 26-10% indomethacinamide over 2-8 h following drug administration.

Animals↗
PubMed1983

Pharmacokinetics of metioprim in normal subjects and patients with impaired renal function.

The pharmacokinetics of metioprim, a new competitive inhibitor of bacterial dihydrofolate reductases, were studied after a single oral dose of 100 mg in two young healthy subjects, four elderly volunteers, and eight patients with impaired renal function. The pharmacokinetic parameters of unchanged metioprim were derived by analyzing plasma level curves using a two-compartment model. Plasma half-lives determined for the beta phase were 10.5 to 11.5 h in young volunteers, 12.0 to 12.9 h in elderly subjects, and 13.2 to 15.3 h in patients with renal impairment. A significant correlation between the overall elimination rate constant and the creatinine clearance was demonstrated.

Adult↗
PubMed1983

[Pharmacokinetics and bioequivalence of various oral formulations of metoclopramide].

Two intraindividual comparative single-dose studies were carried out under carefully controlled conditions on 8 (10) healthy volunteers in order to establish the bioequivalence of 4-amino-5-chloro -N- (2-diethyl-aminoethyl) -2- methoxy-benzamide (metoclopramide) the active principle of Gastrosil tablets and drops, in comparison to the respective formulations, i.e. tablets and drops of a reference drug. In an additional, open single-dose study the pharmacokinetics of metoclopramide were investigated after administration of a newly developed sustained-release dosage form. The analysis of unchanged metoclopramide in plasma was carried out using high-performance liquid chromatography. A 2-compartment open model was taken as a basis for the calculation of the plasma concentration curves and the pharmacokinetic parameters. All oral dosage forms investigated are bioequivalent. Comparing the present results to literature data following i.v. administration of the drug, bioavailabilities between 54-75% could be calculated. The initial distribution of the drug following administration of tablets and drops is very rapid, the terminal elimination half-lives ranges from 4.1-5.7 h and the apparent volumes of distribution were found to be 5.2-5.8 l/kg body weight.

Administration, Oral↗