Comparisons of MR Findings Between Supratentorial and Infratentorial Gangliogliomas.

PURPOSE: Ganglioglioma is an uncommon intracranial disorder. The purpose of our study was to describe the different MR characteristics between supratentorial and infratentorial gangliogliomas and to evaluate the diagnostic value of MR imaging for the disorder. METHODS: The MR images of 33 patients with intracranial gangliogliomas from July 2007 to November 2012 were retrospectively reviewed. We evaluated the images in relation to the following variables: location, size, cystic changes, cortical changes, and enhancement pattern. RESULTS: Histological diagnosis was achieved in all cases by surgery. Tumors were divided into a supratentorial group (n = 24) and an infratentorial group (n = 9) according to their location. In the supratentorial group, tumor dimensions varied from 0.5 to 5 cm (mean dimension, 2.7 cm). Cystic (n = 2), cystic-solid (n = 10), and solid (n = 12) tumors without cortical changes had variable enhancement in this group. In the infratentorial group, tumor dimensions varied from 4 to 7 cm (mean dimension, 5.2 cm). Solid (n = 7) tumors with ipsilateral cerebellar cortical atrophy (n = 7) had remarkable heterogeneous enhancement in this group. CONCLUSIONS: MR imaging features of supratentorial gangliogliomas are non-specific. Relatively larger solid masses with remarkable heterogeneous enhancement and ipsilateral cerebellar cortical atrophy in the infratentorial region are suggestive of ganglioglioma. As such, cerebellar cortical atrophy may be a specific finding that is well demonstrated with MR imaging. Although MR findings can provide some evidence for this rare entity, a differential diagnosis is still needed.

Ureteroscopic management of lower-pole renal calculi: technique of calculus displacement.

PURPOSE: We review our technique of ureteroscopic management of lower pole renal calculi with Nitinol basket displacement and holmium laser stone fragmentation. METHODS: Lower pole calculi are identified with a 7.5F flexible ureteroscope. In patients in whom the laser fiber reduces ureteroscopic deflection, precluding reentry into the lower pole, a Nitinol basket or grasper is used to displace the calculi into an upper pole calix for easier fragmentation. RESULTS: The Nitinol device can be passed into the lower pole through the fully deflected ureteroscope without any loss of deflection. Irrigation is significantly reduced by the basket, but this factor does not impede stone retrieval. CONCLUSIONS: Ureteroscopic management of lower pole stones is a reasonable alternative to SWL or percutaneous nephrolithotomy in low-volume stone disease. If the stone cannot be fragmented in situ, Nitinol basket capture through a fully deflected ureteroscope into a less dependent position facilitates stone fragmentation.

Simplified ureteral stent placement with the assistance of a ureteral access sheath.

PURPOSE: When using a ureteral access sheath following a ureteroscopic procedure, placement of an internal ureteral stent can be simplified by inserting the stent through the sheath without the need to reinsert the cystoscope. MATERIALS AND METHODS: An indwelling ureteral stent with the pull string attached is inserted over the guide wire into the access sheath followed by the pusher. The guide wire is partially withdrawn allowing the stent to form a coil in the renal pelvis, using the pull string to adjust the stent position. The fluoroscopy unit is then focused onto the bladder and the guide wire is slowly withdrawn until its tip is at the level of pubic symphysis. The pusher and guide wire are then removed and the pull string is cut at the urethral meatus. RESULTS: Among 71 cases studied 60 required ureteral stent placement. In 43 of the 60 cases (72%) the ureteral access sheath greatly facilitated ureteroscopy, and a stent was placed through the access sheath in 34 (79%). Stent placement through the access sheath was successful in all cases, with an average time saving of 2.3 minutes per case, compared to placing the stent by reinserting a cystoscope. CONCLUSIONS: If an access sheath has already been placed during a ureteroscopic procedure and stent insertion is deemed necessary, the stent can be easily placed through the access sheath under fluoroscopic guidance without the need to reinsert the cystoscope. Our experience suggests that all urologists who routinely perform ureteroscopic procedures can easily master this timesaving technique.

Induction of polyclonal prostate cancer-specific CTL using dendritic cells transfected with amplified tumor RNA.

Polyvalent cancer vaccines targeting the entire antigenic spectrum on tumor cells may represent a superior therapeutic strategy for cancer patients than vaccines solely directed against single Ags. In this study, we show that autologous dendritic cells (DC) transfected with RNA amplified from microdissected tumor cells are capable of stimulating CTL against a broad set of unidentified and critical prostate-specific Ags. Although the polyclonal CTL responses generated with amplified tumor RNA-transfected DC encompassed as a subcomponent a response against prostate-specific Ag (PSA) as well as against telomerase reverse transcriptase, the tumor-specific CTL were consistently more effective than PSA or telomerase reverse transcriptase CTL to lyse tumor targets, suggesting the superiority of the polyclonal response. Although tumor RNA-transfected DC stimulated CTL, which recognized not only tumor but also self-Ags expressed by benign prostate tissue, these cross-reactive CTL were exclusively specific for the PSA, indicating an immunodominant role of PSA in the prostate cancer-specific immune response. Our data suggest that tumor RNA-transfected DC may represent a broadly applicable, potentially clinically effective vaccine strategy for prostate cancer patients, which is not limited by tumor tissue availability for Ag preparation and may minimize the risk of clonal tumor escape.

Simultaneous measurement of liposome extravasation and content release in tumors.

OBJECTIVE: The success of liposome-based drug delivery systems for tumor targeting relies on maximum extravasation of liposomes into tumor interstitium, as well as optimal release of contents from the liposomes once within the tumor Liposome extravasation and content release are two separate processes that can be individually or jointly manipulated so a method is needed to monitor these two processes independently and simultaneously. In this report, we describe a method to measure liposome extravasation and content release in tumor tissues growing in a rat skinfold window chamber preparation. METHODS: Mixtures of liposomes containing either doxorubicin or calcein, both of which are fluorescent, and liposomes surface-labeled with rhodamine were injected intravenously. Fluorescent, light intensities in a tumor region in two fluorescent channels were measured using an image-processing system. Light intensities of plasma from blood samples were also measured using this system. These measurements were used to calculate the amounts of liposomes and released contents in both plasma and tumor interstitium. The calculations were based on the fact that the liposome surface labels and contents emit fluorescent light at different wavelengths and when encapsulated, the contents fluorescence is self-quenched. The model included equations to account for fluorescent light "cross-contamination" by the two fluorochromes as well as equations relating the measured fluorescent light intensities to the amounts of liposomes and released contents. This method was applied to three situations in which liposome extravasation and content release were manipulated in different, predictable ways. RESULTS AND CONCLUSION: Our results indicate that this method can perform simultaneous independent and quantitative measurements of liposome extravasation and content release. This method can potentially be used to study drug delivery of other carrier systems in vivo.

Thermosensitive liposomes: extravasation and release of contents in tumor microvascular networks.

PURPOSE: The purpose of this study was to determine whether hyperthermic exposure would accelerate drug release from thermosensitive sterically stabilized liposomes and enhance their extravasation in tumor tissues. MATERIALS AND METHODS: In vivo fluorescence video microscopy was used to measure the extravasation of liposomes, as well as release of their contents, in a rat skin flap window chamber containing a vascularized mammary adenocarcinoma under defined thermal conditions (34 degrees, 42 degrees, and 45 degrees C). Images of tissue areas containing multiple blood vessels were recorded via a SIT camera immediately before, and for up to 2 h after i.v. injection of two liposome populations with identical lipid composition: one liposome preparation was surface labeled with Rhodamine-PE (Rh-PE) and the other contained either Doxorubicin (Dox) or calcein at self-quenching concentrations. The light intensity of the entire tissue area was measured at 34 degrees C (the physiological temperature of the skin) for 1 h, and at 42 degrees or 45 degrees C for a second hour. These measurements were then used to calculate the fluorescent light intensity arising from each tracer (liposome surface label and the released contents) inside the vessel and in the interstitial region. RESULTS: The calculated intensity of Rh-PE for the thermosensitive liposomes in the interstitial space (which represents the amount of extravasated liposomes) was low during the first hour, while temperature was maintained at 34 degrees C and increased to 47 times its level before heating, when the tumor was heated at 42 degrees or 45 degrees C for 1 h. The calculated intensity of the liposome contents (Dox) in the interstitial space was negligible at 34 degrees C, and increased by 38- and 76-fold, when the tumor was heated at 42 degrees and 45 degrees C for 1 h, respectively. Similar values were obtained when calcein was encapsulated in liposomes instead of Dox. A similar increase in liposome extravasation was seen with nonthermosensitive liposomes, but negligible release of Dox occurred when the window chamber was heated to 45 degrees C for 1 h. Extravasation of liposomes continued after heating was stopped, but content release stopped after removal of heat. Release of Dox from extravasated liposomes was also seen if heating was applied 24 h after liposome administration, but no further enhancement of liposome extravasation occurred in this case. CONCLUSIONS: Our data suggest that hyperthermia can be used to selectively enhance both the delivery and the rate of release of drugs from thermosensitive liposomes to targeted tissues.

Inhibition of radiation-induced up-regulation of leukocyte adhesion to endothelial cells with the platelet-activating factor inhibitor, BN52021.

PURPOSE: The inflammatory process is likely involved in normal tissue damage after radiation exposure, yet few studies have directly evaluated the factors that might be involved in the regulation of inflammation after irradiation in vivo. We tested the hypothesis that platelet-activating factor, a neutrophil agonist synthesized by endothelial cells, is involved in the upregulation of radiation-induced leukocyte-endothelial cell interactions by using an inhibitor of its receptor, BN52021. METHODS AND MATERIALS: Fischer-344 rats with dorsal skin-fold window chambers were randomized to three experimental groups: control (sham irradiation); 6 Gy radiation; and 6 Gy + BN52021. BN52021 (0.5 mg/kg) was administered 5 min prior to 6 Gy radiation. Leukocytes were stained in vivo with i.v. acridine orange for visualization with fluorescent microscopy. Venous vessel diameters were measured and number of rolling leukocytes were counted per 30-s period. The number of adhering leukocytes per unit surface area was also determined. Differences among the three experimental groups for rolling and adhering leukocytes were analyzed using a mixed-effects linear model with vessel shear rate used as a covariate. Results are reported as means +/- standard errors. RESULTS: Irradiation caused upregulation of leukocyte rolling, as compared with sham-treated controls (p = 0.04): the BN compound in addition to radiation did not downregulate this effect. Irradiation also upregulated leukocyte adhesion (p < 0.001), but the addition of BN52021 prior to irradiation blocked this effect. The drug did not affect heart rate or blood pressure. CONCLUSIONS: These results support the hypothesis that radiation-induced upregulation of leukocyte adhesion is mediated by platelet-activating factor. These results are consistent with prior reports that platelet-activating factor is not involved in leukocyte rolling, which involves separate families of adhesion molecules from those that regulate adhesion. BN52021, a ginkolide, or other related drugs might provide a useful pharmacological means to prevent or ameliorate inflammatory pathways that are invoked after radiation exposure.

Differences in leucocyte-endothelium interactions between normal and adenocarcinoma bearing tissues in response to radiation.

Previously, we demonstrated that the interaction between leucocytes and endothelial cells in tumour tissues is greatly diminished compared with normal tissues under several induced inflammatory conditions. Radiation has been reported to cause release of inflammatory mediators and to promote neutrophil adhesions to cultured endothelial monolayers. In this study, we tested the hypothesis that radiation would cause increased leucocyte rolling and adhesion in both tumour and normal tissues. We examined these two parameters in response to 6 Gy of gamma-radiation in mammary adenocarcinomas implanted into rat skinfold window chambers as well as normal (i.e. non-tumour-bearing) preparations. Leucocyte rolling and adhesion were measured in terms of flux of rolling leucocytes (F(rolling)) and density of adhering leucocytes (D(adhering)) in microvessels. F(rolling) and D(adhering) were measured in two groups of preparations: irradiated and control. In normal preparations, F(rolling) and D(adhering) were both increased significantly by radiation. In contrast, in adenocarcinoma-bearing preparations, F(rolling) and D(adhering) were either unchanged (in the tumour centre) or reduced (in tumour periphery and the normal tissue surrounding the tumour) by radiation. Radiation did not cause changes in haemodynamics in these preparations, thus the observed changes in leucocyte rolling and adhesion could not be accounted for by haemodynamic factors. These results indicate that: (1) in normal preparations, radiation could cause inflammation as manifested by increased leucocyte rolling and adhesion; and (2) in tumour-bearing preparations, radiation caused changes in the vascular surface properties such that they became less adhesive to leucocytes. Such differences in radiation response may have important implications for radiation therapy and provide new insights into the unique features of tumours.

Measurement of material extravasation in microvascular networks using fluorescence video-microscopy.

We have developed a new method using fluorescence videomicroscopy to quantitate the extravasation of intravenously injected materials. This method can measure the relative plasma concentration of, and the vascular permeability to, these materials in microcirculatory preparations which contain multiple blood vessels in a field of view. The image of a tissue area containing multiple blood vessels is recorded via a SIT camera immediately before, and for an extended period after, the intravenous injection of a bolus of fluorescent test tracers. The videotape is analyzed off-line. At various time points, the light intensities of the entire tissue area and of several spots over selected vessels are measured. These measurements are then used to calculate the fluorescent light intensities arising from the tracers inside vessels (Iv) and in the interstitial region (Ii). Iv represents the relative amount of the tracers in the plasma, and Ii represents that in the interstitium. Iv and Ii are used to calculate an average permeability (P) for the vessels in the observed region. The benefit of this method is that it can be used to compare permeability of various tissues of interest or to serially evaluate changes in P in the same tissue over time. In this study, it was applied to measuring P to albumin as well as to liposomes in granulating and implanted tumor tissues in a rat skin flap window chamber. Changes in permeability to a small molecule (sulforhodamine B) before and during bradykinin application were also measured. The results of these experiments indicate that the relative plasma concentrations predicted by this method conformed well to those measured directly from blood samples, and the measured permeability values were consistent with previously published data. Therefore, this method provides a valid approach for quantitatively measuring the extravasation of intravenously injected molecular and colloidal materials in microcirculatory preparations. The method has a set of defined experimental conditions and assumptions that cannot be violated, however, or erroneous results can be obtained.

Increased microvascular permeability contributes to preferential accumulation of Stealth liposomes in tumor tissue.

Stealth liposomes have recently emerged as a promising antitumor drug delivery system, yet no studies have been reported to examine their dynamic behavior at the microcirculatory level. In this investigation, we have used in vivo fluorescence videomicroscopy to study the decay in plasma concentration and the interstitial accumulation of Stealth and conventional liposomes in tumor and granulating tissue microcirculatory preparations. Fluorescently labeled Stealth or conventional liposomes were injected i.v. into rats bearing dorsal skinflap window chambers, some of which contained a vascularized mammary adenocarcinoma. After injection, fluorescent light intensities arising from liposomes within blood vessels and the interstitium were measured over time. These measurements were used to derive plasma pharmacokinetics and vascular permeability coefficients for each liposome species in both tumor and granulating normal tissues. Within the first 90 min after injection, Stealth liposome accumulation in the tumor interstitium was 3-4-fold that for conventional liposomes. The percentage of administered liposomes remaining in the circulation at the end of 90 min was 60.2% for Stealth and 20.4% for conventional liposomes. Tumor vascular permeability was 3.42 +/- 0.78 x 10(-7)cm/s for Stealth and 1.75 x 0.38 x 10(-7)cm/s for conventional liposomes. In normal granulating tissues permeability for the 2 constructs was equivalent at 0.8-0.9 x 10(-7)cm/s. In conclusion, preferential accumulation of Stealth liposomes in tumors was attributable to a combination of slower plasma clearance and higher vascular permeability relative to conventional liposomes. Our method of combining in vivo microscopy with a tumor microcirculatory model provides a unique approach to study quantitatively the delivery of liposomes to tumor tissues, since it can be used to study the process in real time at the microcirculatory level.

Possible mechanism(s) for permeability recovery of venules during histamine application.

Histamine is known to cause a substantial increase in the permeability of venules to both water and proteins. However, this increase is transient, i.e., the initially elevated permeability returns toward control levels, or "recovers," even during continuous histamine stimulation. In this investigation, we attempted to identify the possible chemical signal(s) initiating the permeability recovery process in single venules of rat mesentery. Specifically, we tested whether histamine's binding to H2 receptors and/or the production of prostacyclin by endothelial cells was involved in this process. To achieve this aim, the time course of endothelial cells was involved in this process. To achieve this aim, the time course of histamine-induced changes in permeability to alpha-lactalbumin was measured in the presence of H2 receptor antagonist (cimetidine) or of prostacyclin synthetase inhibitor (tranylcypromine), respectively. Permeability of individually perfused microvessels was measured using fluorescence microscopy. The results demonstrated that permeability recovery was not affected by the H2 receptor antagonist but was suppressed or even abolished by the prostacyclin synthesis inhibitor. Therefore, these results suggest that the production of prostacyclin by endothelial cells might serve as one chemical signal to initiate the permeability recovery process, whereas histamine's binding to H2 receptors is not involved in this phenomenon.

Diminished leukocyte-endothelium interaction in tumor microvessels.

Leukocyte-endothelium interaction in vivo consists of the rolling of leukocytes along the vascular wall and, under certain conditions, their adherence to endothelial cells. In a rat tumor microcirculation model (mammary adenocarcinoma implanted in rat skinfold window chamber), we demonstrated that this interaction, measured as flux of rolling leukocytes and density of adhering leukocytes, was significantly reduced in tumor microvessels compared to normal microvessels, both under control conditions and during inflammation induced by N-formylmethionylleucylphenylalanine (1 microM), bacterial lipopolysaccharide (1 microgram/ml), or tumor necrosis factor alpha (500 units/ml). We also measured the blood flow shear rate in the tumor and normal microvessels and found that the difference in shear rate between the two types of microvessels could not account for the differences in leukocyte-endothelium interaction. The diminished leukocyte-endothelium interaction in tumors under various stimulated conditions suggests that a number of adhesion molecules may not be expressed properly on tumor endothelial cells.

Transient venular permeability increase and endothelial gap formation induced by histamine.

Histamine is known to increase permeability of venules and to cause formation of gaps between endothelial cells. The permeability increase is transient, lasting only a few minutes during continuous histamine application. In this study, three series of experiments were conducted to test the hypothesis that the transient permeability increase is due to transient formation of endothelial gaps. First, the time course of permeability changes to alpha-lactalbumin during 15 min of 10(-3) M histamine suffusion was determined on single venules in the rat mesentery. With histamine application, permeability increased initially, peaked with an average of fivefold increase around the 3rd min, and then declined toward control. Second, the temporal development of endothelial gaps during histamine treatment was studied with electron microscopy. The fraction of gaps among all junctions increased from 2% at control to 26.5% at 3 min and then decreased toward control. Finally, gap morphology data were obtained from the individual venules whose permeability response to a given period of histamine treatment had been recorded. The temporal development of the gaps was mirrored by that of permeability. Because both permeability and endothelial gaps followed similar developmental patterns during histamine treatment, the result of our study supports the hypothesis that the histamine-induced transient permeability increase is due to transient formation of endothelial gaps.

Endothelial surface charge of intestinal mucosal capillaries and its modulation by dextran.

Capillary endothelial surface charge was investigated by perfusing the intestinal circulation of anesthetized rats in situ with 0.1 or 10 mg/ml native ferritin (NF, pI = 3.8-4.2) or with 0.1 mg/ml cationized ferritin (CF, pI greater than 10.0) for 5 min, with or without 5% Dextran 40. Ferritin binding was quantified by electron microscopy. All electron micrographs of capillaries perfused with NF showed some NF binding. Mean NF particle densities (particles/microns) were significantly greater at vesicle necks (PDv) than elsewhere on the endothelial surface (PD). Capillaries perfused with CF showed binding in only 60% of the transverse sections examined. The binding was very marked in a large proportion of these vessels. Mean CF particle densities were significantly greater at fenestrae (PDf) than elsewhere. These results demonstrate that mucosal capillaries have a variable negative electrostatic charge on the endothelial surface and support the hypothesis that some vesicle diaphragms act as preferential attractors for anionic macromolecules. Such structures could promote transendothelial vesicular transport of albumin. Dextran significantly decreased PD for NF from 25.4 +/- 2.4 (SEM) to 13.1 +/- 0.9 and PD, PDv, and PDf for CF from 45.9 +/- 4.6 to 31.0 +/- 2.7, from 62.1 +/- 6.2 to 43.6 +/- 5.4, and from 152.9 +/- 15.5 to 114.5 +/- 8.6, respectively. The above responses result from dextran's weak interaction with the endothelial surface. Dextran reduces access of ferritin molecules to the cell surface by steric hindrance and/or electrostatic shielding of the glycocalyx.