Biomedical subjects

Marc Kalinowski

Publications and source records attributed to Marc Kalinowski.

11 recordsLinked to original sources

PubMed2006

Added value of gastrin receptor scintigraphy in comparison to somatostatin receptor scintigraphy in patients with carcinoids and other neuroendocrine tumours.

Gastrin receptor scintigraphy (GRS) is a new imaging method primarily developed for the detection of metastases of medullary thyroid carcinoma (MTC). As gastrin-binding CCK(2) receptors are also expressed on a variety of other neuroendocrine tumours (NET), we compared GRS to somatostatin receptor scintigraphy (SRS) in patients with NET. SRS and GRS were performed within 21 days in a series of 60 consecutive patients with NET. GRS was directly compared with SRS. If lesions were visible on GRS but not detectable by SRS, other imaging modalities (MRI, CT) and follow-up were used for verification. Of the 60 evaluable patients, 51 had carcinoid tumours, 3 gastrinomas, 2 glucagonomas, 1 insulinoma and 3 paragangliomas. The overall tumour-detection rate was 73.7% for GRS and 82.1% for SRS. In the 11 patients with negative SRS, GRS was positive in 6 (54.5%). Based on the number of tumour sites detected and the degree of uptake, GRS performed better than SRS in 13 patients (21.7%), equivalent images were obtained in 18 cases (30.0%) and SRS performed better in 24 (40.0%) cases. In six of the SRS positive patients, 18 additional sites of tumour involvement could be detected. Overall, GRS detected additional tumour sites in 20% of the patients. Localisation of the primary tumours or their functional status had no influence on the outcome of imaging. GRS should be performed in selected patients as it may provide additional information in patients with NET with equivocal or absent somatostatin uptake.

Adult↗

PubMed2005

Airway management under general anaesthesia in pigs using the LMA-ProSeal: a pilot study.

OBJECTIVE: Evaluation of the LMA-ProSeal for positive pressure ventilation (PPV) in the pig. STUDY DESIGN: Prospective observational study. ANIMALS: Twelve German country pigs, weighing 25-62 kg. METHOD: Lungs of pigs were mechanically ventilated under general anaesthesia using the LMA-ProSeal. The ease of insertion, number of attempts and total time until placement of the LMA-ProSeal and gastric tube were recorded. Bronchoscopy was performed to determine the position of the LMA-ProSeal and to detect signs of aspiration. Ventilation variables and the leak airway pressure (P(leak)) were measured. An arterial blood gas sample was taken to determine the adequacy of ventilation. RESULTS: The airway was secured in all pigs within 39 +/- 19 seconds (27-51). Different sizes of LMA-ProSeal were used; up to 30 kg: size 3, up to 43 kg: size 4; and above 43 kg: size 5. In all but one animal the P-LMA and gastric tube were inserted at the first attempt. In nine animals gastric fluid was drained through the gastric tube. There was no evidence of aspiration in any animal. The mean [+/-SD (95%CI)]P(leak) was 28.8 +/- 7.5 cm H(2)O (24.06-33.60) and normal ventilation was achieved in all animals. CONCLUSIONS: The results of this study indicate that the airway of pigs weighing 25-62 kg can be secured safely and reliably with the sizes 3, 4 and 5 LMA-ProSeal. CLINICAL RELEVANCE: Endotracheal intubation in pigs can be difficult so there is a risk of hypoxemia in the apnoeic animal. With the LMA-ProSeal the airway can be secured rapidly, safely and reliably. Use of the Standard-LMA under PPV can be associated with gas leakage into the stomach and the subsequent risk of gastric distension and regurgitation. Both the ability to drain the stomach and the high P(leak) of the LMA-ProSeal could contribute to improved protection against aspiration under PPV.

Anesthesia, General↗

PubMed2004

Effects of altering infusion parameters on intimal hyperplasia following local catheter-based delivery into the rabbit iliac artery.

BACKGROUND: Efficient local gene or drug therapy requires optimized application modalities to avoid vessel damage, which might lead to increased neointimal hyperplasia. Aim of the study was to evaluate different application parameters for local delivery using the channeled balloon catheter in order to minimize vessel trauma induced by local application. METHODS AND RESULTS: Sixty cholesterol fed rabbits were randomly enrolled into twelve groups of different local application parameters: group I, application pressure 2atm/application volume 1ml physiologic saline; group II, 2atm/2ml; group III, 2atm/5ml; group IV, 4atm/1ml; group V, 4atm/2ml; group VI, 4atm/5ml. The other six groups received Ringer's solution instead of saline. Administration of the solution was randomly performed in one iliac artery using the channeled balloon catheter with simultaneous balloon angioplasty (8atm). The contralateral iliac artery served as a control and was treated with balloon angioplasty only. Four weeks after local therapy, calibrated angiography was performed; the animals were sacrificed, vessel segments were excised and quantitative morphometric measurements were obtained. In none of the animals acute complications, e.g. dissection, thrombosis or perforation of the vessel, was noted. Up to an application pressure of 4atm and an application volume of 5ml, no significant neointima formation was seen compared to arteries which underwent angioplasty only. Additionally, no significant differences between saline and Ringer's solution were detected. In a multivariate analysis, neither application pressure nor volume were found to have a statistically significant influence on the amount of neointimal hyperplasia. CONCLUSIONS: Local application of "drugs" using the channeled balloon catheter is safe and feasible without significant induction of neointimal hyperplasia compared to angioplasty, if an application volume of 5ml and a pressure of 4atm is not exceeded.

Angiography↗

PubMed2004

Effects of different application parameters on penetration characteristics and arterial vessel wall integrity after local nanoparticle delivery using a porous balloon catheter.

Catheter-based local delivery of drug loaded nanoparticles agents offers a potential therapeutic approach to reducing restenosis. However, high delivery pressures and large volumes of infusates may cause severe vascular damage and increase intimal thickening. Therefore, we investigated the penetration pattern and vessel wall integrity of fluorescence-labelled nanoparticles (217 nm in diameter) into the non-atherosclerotic aorta abdominalis of New Zealand white rabbits in dependence of the volume (2.5 and 5 ml) and concentration (0.5 and 1 mg/ml) of the nanoparticle suspension, as well as the infusion pressure (2 and 4 atm) using a channelled balloon catheter (SCIMED REMEDY model RC 20/2.5). The location and penetration characteristics of nanoparticles in the arterial vessel wall were visualized using confocal laser scanning microscopy and transmission electron microscopy (TEM). Catheter design and infusion pressure form a radial particle stream through intima and media into the adventitial layer of the aorta abdominalis. Infusion pressures of 4 atm in combination with high particle concentrations lead to effective nanoparticle delivery without severe vessel wall disruptions. Endothelium of the treated vessel segments was slightly affected during catheter insertion showing partly denudation of the innermost cell layer. TEM micrographs underlines transport functional properties of the vasa vasorum inside the vessel wall. Consequently, local delivery efficiency of nanoparticulate carriers is critically affected by infusion pressure, and concentration of carrier suspensions. These factors need to be taken into consideration for the design of in vivo experiments.

Animals↗

PubMed2003

Adjunctive techniques in percutaneous mechanical thrombectomy.

Percutaneous mechanical thrombectomy is an established method in interventional radiology and refers to the removal of acute embolic or thrombotic occlusive material in arteries, veins, or vascular grafts using percutaneous transluminal methods. However, initial complete removal of occlusive material can be achieved only in a minority of patients. The amount of removed material varies with the age and composition of the occlusive material. To achieve sufficient revascularization, adjunctive use of a variety of percutaneous endovascular recanalization techniques is necessitated. Additional treatment with local intra-arterial fibrinolysis, balloon angioplasty, stent implantation, endoluminal atherectomy, and other measures results in primary technical success rates of 70% to 100% for revascularization of acutely occluded vessels. The above-mentioned different techniques should not be viewed as competitive treatment modalities, rather a synergistic approach should be offered. The aim of this report is to review different adjunctive techniques in percutaneous mechanical thrombectomy with emphasis on techniques, mechanisms of action, experimental and clinical results, potential complications, and their potential role in view of clinical pathways to treat acute limb ischemia.

Algorithms↗

PubMed2003

1-molar gadobutrol as a contrast agent for computed tomography: results from a comparative porcine study.

RATIONALE AND OBJECTIVES: To evaluate prospectively the efficacy of gadobutrol as contrast agent for computed tomography (CT) compared with iodinated contrast media in a porcine animal model. METHODS: In 8 domestic pigs (35 +/- 4 kg body weight [BW]), continuous spiral CTs of the chest and abdomen were performed using either 2 mmol/kg BW Gadovist 1.0 (1 mol/L gadobutrol) intravenously or Ultravist (300 mg I/mL iopromide) (slice 5 mm, table feed 7.5 mm, reconstruction increment 5 mm). One week later, the same animals were examined using the same protocol with the other contrast agent. In 2 additional animals, serial CTs were performed at the same level using gadobutrol or iopromide on day 1 and the alternate agent on day 8 inches order to determine contrast media kinetics, peak enhancement, and time enhancement-product in important vascular regions and parenchymal organs (abdominal aorta, inferior vena cava, liver, and renal parenchyma). Peak enhancement (net increase compared with nonenhanced baseline values) was measured in Hounsfield units (HU) in defined regions of interest. RESULTS: In vivo, the mean peak enhancement 5, 15, 30, and 120 seconds in the abdominal aorta after injection of 2 mL/kg BW gadobutrol and iopromide was 200 +/- 11, 224 +/- 10, 261 +/- 13, and 95 +/- 9 HU versus 232 +/- 10, 298 +/- 10, 152 +/- 11, and 123 +/- 10 HU, respectively. Differences in enhancement of vascular structures was statistically significant (P < 0.05) in carotid arteries (235 +/- 20 HU for gadobutrol and 264 +/- 19 HU for iopromide) and the aortic arch (261 +/- 14 HU for gadobutrol and 279 HU +/- 13 HU for iopromide). No statistical significance was seen in all other measured vascular structures and parenchymal organs. CONCLUSION: Contrast-enhanced CT with 1 mol/L gadobutrol in a dose of 2 mmol/kg BW resulted in an excellent vascular and parenchymal enhancement in most vascular regions and parenchymal organs similar to an equivalent volume of 300 mg/mL iodinated contrast media.

Animals↗

PubMed2002

X-ray digital subtraction angiography with 1 mol/L gadobutrol: results from a comparative porcine study With iodinated contrast agents.

RATIONALE AND OBJECTIVES: To evaluate prospectively diagnostic accuracy of 1 mol/L gadobutrol as a contrast agent for intraarterial x-ray digital subtraction angiography (DSA) in comparison to iodinated, nonionic contrast media and 0.5 mol/L gadolinium-DTPA. METHODS: Flush arteriograms (ascending, descending, abdominal aorta, iliac, and femoral arteries) and selective angiograms (carotid, renal, and visceral arteries) were obtained from bilateral femoral arterial access (5 F sheaths) in 10 domestic pigs (70 kg body weight). Digital subtracted angiograms were obtained during injection of undiluted 1 mol/L gadobutrol, 300 mg I/mL iopromide, or 0.5 mol/L gadopentetate. Injection parameters (volume and velocity) were similar for all three contrast agents. In paired arteries, two different contrast media were used during the same angiographic run. Diagnostic quality and accuracy of the angiograms were evaluated on a three-step scale by three independent blinded investigators. RESULTS: Sufficient nonselective angiographic images were obtained in 90% of cases using iodinated contrast material. Gadobutrol achieved sufficient nonselective angiograms in 64%. Selective angiograms were sufficient in 98% using iodinated contrast material, 90% using 1 mol/L Gadobutrol and 48% using 0.5 mol/L Gd-DTPA. Adverse reactions to any of the used contrast agents were not noted. CONCLUSION: One mol/L Gadobutrol solution allows x-ray digital subtraction angiography with a diagnostic accuracy equivalent to 300 mg/mL iodinated contrast media, if selective injections are performed. Flush aortograms are of inferior image quality to iodinated contrast material.

Angiography, Digital Subtraction↗

PubMed2002

Paclitaxel inhibits proliferation of cell lines responsible for metal stent obstruction: possible topical application in malignant bile duct obstructions.

RATIONALE AND OBJECTIVES: To evaluate a dose dependent inhibitory effect of paclitaxel to assess a possible local application for biliary tract malignancies in conjunction with stent placement. METHODS: Cell cultures of the three different cell types (human epithelial gallbladder cells [HEGC], human fibroblasts [HF; PA 314 wt] and pancreatic carcinoma cells [PC; P181]) were incubated for 20 minutes at 37 degrees C with increasing doses of paclitaxel (1.0 x 10(-4) - 1.0 x 10(2) micromol). Half of the cultures were then incubated without paclitaxel, the other half with paclitaxel for 20 minutes, 24 hours, or 72 hours. Cell proliferation was detected by photometric measurements of mitochondrial dehydrogenase activity (MTT assay). RESULTS: Incubation of cell cultures with paclitaxel resulted in a dose dependent and cell specific inhibition of cell proliferation. Concentrations of 1.0 x 10(-4) (and higher) paclitaxel for 20 minutes resulted in a inhibition of cell proliferation of HEGC (28%), PA (26%), and HF (17%). A prolonged paclitaxel incubation (up to 72 hours) resulted in an inhibitory effect on cell proliferation of HEGC (40%), PA (45%), and HF (39%). Cytotoxic effects, manifested by development of vacuoles and damage of cell integrity were seen at concentrations above 1.0 x 10(1) for both the short and long term incubation. CONCLUSIONS: Paclitaxel incubation resulted in a dose dependent inhibition of cell proliferation of human epithelial gallbladder cells, human fibroblasts and pancreatic carcinoma cells. This inhibitory effect of paclitaxel on the cell lines could serve as the basis to develop drug coated or drug eluting stents for malignant biliary strictures.

Antineoplastic Agents, Phytogenic↗

PubMed2002

Deposition of nanoparticles in the arterial vessel by porous balloon catheters: localization by confocal laser scanning microscopy and transmission electron microscopy.

Restenosis remains the major limitation of percutaneous transluminal angioplasty (PTA) and stenting in the treatment of patients with atherosclerotic disease. Catheter-based local delivery of pharmacologic agents offers a potential therapeutic approach to reducing restenosis and minimizing undesirable systemic side effects. However, the intramural retention of liquid agents is low. Therefore, to achieve a sustained and regional release of the therapeutic agent it must be encapsulated in nanoparticle carrier systems. The purpose of this study was to investigate the size dependence of the penetration of nanoparticles after local delivery into the vessel wall of the aorta abdominalis of New Zealand white rabbits. Two milliliters of a 0.025% fluorescence-labeled polystyrene nanoparticle suspension with diameters ranging from 110 to 514 nm were infused at 2 atm and at constant PTA pressure of 8 atm into the aorta abdominalis. After the infused segments were removed, the location of nanoparticles was visualized using confocal laser scanning microscopy and transmission electron microscopy. The study demonstrates a size-dependent nanoparticle penetration into the intact vessel wall. While nanoparticles of about 100 and 200 nm were deposited in the inner regions of the vessel wall, 514-nm nanoparticles accumulated primarily at the luminal surface of the aorta. The observations confirm that size plays a critical role in the distribution of particles in the arterial vessel wall. It is additionally influenced by the formation of pressure-induced infusion channels, as well as by the existence of anatomic barriers, such as plaques, at the luminal surface of the aorta or the connective elastic tissue.

Animals↗

PubMed2002

Comparative study of MR sialography and digital subtraction sialography for benign salivary gland disorders.

BACKGROUND AND PURPOSE: MR sialography has become an alternative imaging technique for ductal salivary gland diseases. We compared the diagnostic accuracies of MR sialography and digital subtraction sialography in patients with successful completion of both examinations and benign salivary gland disorders. METHODS: In a prospective study, we attempted to examine salivary glands in 80 patients with clinically suspected diagnoses of sialadenitis and/or sialolithiasis. Each patient underwent digital subtraction sialography and MR sialography. MR sialography was obtained with a T2-weighted single-shot turbo spin-echo sequence (TR/TE 2800/1100 msec, acquisition time 7 seconds), with use of a quadrature head coil. Final diagnoses were confirmed by clinical follow-up and results of biopsy (n = 9) or surgery (n = 19). RESULTS: Failure rate was 5% (four of 80) for MR sialography and 14% (11 of 80) for digital subtraction sialography. Eighty-one salivary glands (48 parotid, 33 submandibular) in 65 patients were successfully visualized with both modalities. MR sialography depicted the main ductal system and first- and second-order branches, whereas digital subtraction sialography was able to depict third-order branches. Sensitivity and specificity to diagnose chronic sialadenitis were 70% and 98% with MR and 96% and 100% with digital subtraction sialography. MR sialography enabled diagnosis of sialolithiasis with a sensitivity of 80% and a specificity of 98% versus 90% and 98% for each with digital subtraction sialography. CONCLUSION: MR sialography with a heavily T2-weighted sequence is highly successful in the noninvasive visualization of the ductal system of major salivary glands. It is useful for diagnosing sialolithiasis and sialadenitis. Digital subtraction sialography, an invasive technique, had a substantial procedural failure rate, particularly for the submandibular duct. However, because of its higher spatial resolution, successfully completed digital subtraction sialography achieved superior diagnostic information compared with that of MR sialography.

Adolescent↗

PubMedDate not supplied

Local administration of NF-kappa B decoy oligonucleotides to prevent restenosis after balloon angioplasty: an experimental study in New Zealand white rabbits.

PURPOSE: To evaluate the efficacy of NF-kappa B oligonucleotides (ODN) administered by local administration with the channeled balloon catheter to prevent restenosis after balloon angioplasty in restenotic iliac arteries of New Zealand white rabbits. MATERIALS AND METHODS: In vitro, 8000 rabbit vascular smooth muscle cells (rVSMC) where transfected with a liposomal carrier (TfX50) with 100 ng of decoy and scrambled ODN. Inhibition of proliferation was measured using a MTT assay after 24 hours in comparison to control. In vivo, 22 male New Zealand White rabbits were fed a 1% cholesterol diet and received denudation of both common iliac arteries with a 3 mm balloon catheter to induce an arterial stenosis. Four weeks after stenosis induction, local application of NF-kappa B in two different concentrations (1 mug: n = 14; 10 mug: n = 8) was performed randomly on one common iliac artery. Scrambled oligonucleotides without specific binding capacities were injected into the contralateral side. The channeled balloon catheter allows simultaneous balloon dilation (8 atm) of the stenosis and local application of a drug solution (2 atm). Four weeks after local drug delivery the animals were killed and the vessels were excised and computerized morphometric measurements were performed. RESULTS: NF-kappa B decoy ODN but not scrambled ODN inhibited proliferation of rVSMC in vitro. Following local ODN application in the animals, no acute vascular complications were seen. NF-kappa B ODN resulted in a statistically non significant reduction of neointimal area compared to the control group. The neointimal area was 0.97 mm(2) using 1 mug NF-kappa B ODN compared to 0.98 mm(2) in the control group. The higher dose resulted in a neointimal area of 0.97 mm(2) compared to 1.07 mm(2) at the control side. CONCLUSIONS: Local drug delivery of NF-kappa B ODN using the "channeled balloon" catheter could not reduce neointimal hyperplasia in stenostic rabbit iliac arteries. Application modalities have to be improved to enhance the effect of the local application to prevent restenosis after balloon angioplasty.

Angioplasty, Balloon↗