Intracellular events in the assembly of chylomicrons in rabbit enterocytes

The aim of this study was to determine the intracellular events in chylomicron assembly in adult villus enterocytes. We have used novel methods for separation of the intracellular components of the secretory compartment [rough and smooth endoplasmic reticulum (RER and SER, respectively) and Golgi], and their membrane and luminal components, from villus enterocytes isolated from rabbit small intestine. The steady state composition of the components of the secretory compartment and the intracellular pools of newly synthesized apolipoprotein B-48 (apoB-48) and triacylglycerol (TAG) was determined. The observations indicate that the SER is the main site of TAG synthesis and of chylomicron assembly. Newly synthesized apoB-48 and TAG accumulate in the SER membrane and are transferred into the lumen in a microsomal triglyceride transfer protein-dependent step. In enterocytes isolated from chow-fed rabbits, in which fat absorption is relatively slow, transfer of apoB-48 and TAG from the SER membrane into the lumen appears to be rate limiting. In enterocytes from fat-fed rabbits, TAG accumulates in the lumen of the SER, suggesting that movement out of the SER lumen becomes rate limiting, when chylomicron secretion is markedly stimulated. In these cells, the cytosolic TAG also increased to 450 microgram/g enterocytes, compared with 12 microgram/g enterocytes from chow-fed rabbits, indicating that transfer of TAG from the SER membrane into the secretory pathway can become saturated, so that newly synthesized TAG moves into the cytosol.

Diagnostic quality in endoscopic retrograde cholangiopancreatography: comparison between lodixanol and lopromide

BACKGROUND AND STUDY AIMS

The contrast medium for endoscopic retrograde cholangiopancreatography (ERCP) must produce adequate images, whilst keeping the risk of complications to a minimum. There is a theoretical reason to suppose that a dimeric isosmolar medium may be superior to a monomeric hyperosmolar medium. We have compared two such media in a triple-centre double-blind randomized study on patients referred with a clinical indication for ERCP.

PATIENTS AND METHODS

A total of 160 patients were randomly allocated to either lodixanol or lopromide. Assessments were made of the quality of images and the complications encountered.

RESULTS

A total of 151 patients were evaluated. Apart from a trend towards better diagnostic quality for main pancreatic duct imaging with lodixanol, there were no differences between the two groups. The overall frequencies of adverse events were similar

CONCLUSIONS

lodixanol is a safe and effective water-soluble contrast medium for ERCP, comparable to lopromide, but despite theoretical advantages lodixanol has no clear practical benefit.

Long-term insulin treatment of 3T3-L1 adipocytes results in mis-targeting of GLUT4: implications for insulin-stimulated glucose transport

AIMS/HYPOTHESIS

Insulin stimulates glucose transport in adipose and muscle tissue by the translocation of a specialised pool of intracellular GLUT4-containing vesicles to the cell surface. It is well established that defective insulin-stimulated GLUT4 translocation is associated with insulin resistance. Long-term insulin treatment (500 nmol/l for 24 h) of 3T3-L1 adipocytes has previously been shown to decrease cellular GLUT4 content and reduce insulin-stimulated GLUT4 translocation. Here, we test the hypothesis that the insulin resistance observed after long-term insulin treatment arises by the selective loss of GLUT4 from a specific intracellular compartment.

METHODS

Using iodixanol gradient centrifugation we have separated intracellular GLUT4 containing membranes into two distinct populations corresponding to recycling endosomes and a distinct intracellular compartment which probably represents GLUT4 storage vesicles (GSVs).

RESULTS

A short-term insulin stimulation reduced the content of GLUT4 in the GSV fraction (51 +/- 3.5%) with only a modest decrease from the endosomal fraction (23 +/- 2.6%). Long-term insulin treatment decreased cellular GLUT4 content by about 40% and diminished the ability of a short-term insulin challenge to promote GLUT4 translocation. We further show that this depletion of cellular GLUT4 is selectively from the GSV fraction (68 +/- 7% decrease compared to untreated cells).

CONCLUSIONS/INTERPRETATION

Such data argue that long-term insulin treatment results in the mis-targeting of GLUT4 such that it no longer accesses the GSV compartment. These data imply that defective targeting of GLUT4 away from the GSV compartment plays an important role in the aetiology of insulin resistance.

Abdominal lymphoma staging: is MR imaging with T2-weighted turbo-spin-echo sequence a diagnostic alternative to contrast-enhanced spiral CT?

PURPOSE

To evaluate the diagnostic value of MR imaging in abdominal lymphoma staging, in comparison with that of the established spiral CT, within the context of a prospective study.

METHODS

50 patients with non-Hodgkin (n = 27) and Hodgkin lymphoma (n = 23) were examined with a plain T2-weighted TSE sequence (parameters: TE 90 ms, TR >2.500 ms, slice thickness 8 mm, slice interval 0.8 mm, ETL 20, NEX 4), and with spiral CT following oral and intravenous administration of contrast agent.

RESULTS

Both CT and MR imaging agreed in showing abdominal lymphomas in 34/50 cases. The size of the detected lymphomas was between 1.5-9 cm (mean: 4.3 +/-2.2 cm). In the analysis of the individual lymph node sites, CT showed involvement of the paraaortic lymph nodes in 29/50 patients, compared with 28/50 in MRI, and involvement of the portal lymph nodes in 15/50, compared with 12/50. Both techniques showed the iliac lymph nodes in 21/50 patients, the inguinal lymph nodes in 10/50, and the mesenteric lymph nodes in 11/50. Both techniques also showed focal organ lesions in 12/50 cases.

CONCLUSIONS

In the staging of abdominal lymphomas, MR imaging with a T2-weighted TSE sequence can be regarded as equal to spiral CT in the detection of lymph adenopathy and the demonstration of focal organ lesions. In addition to the absence of ionizing radiation, the advantage of MR imaging is that there is no necessity for oral or intravenous administration of contrast agent.

Vena cavography with CO(2) versus with iodinated contrast material for inferior vena cava filter placement: a prospective evaluation

PURPOSE

To determine whether carbon dioxide (CO(2)) vena cavography can safely guide the placement of inferior vena cava (IVC) filters.

MATERIALS AND METHODS

One hundred nineteen patients were prospectively enrolled in this study. CO(2 )cavograms were obtained and evaluated for IVC diameter, location of renal veins, and presence of thrombus and venous anomalies. If CO(2 )cavography was judged to be adequate, an IVC filter was deployed. After filter placement, cavography was performed with iodinated contrast material; these images were compared with the CO(2) cavograms.

RESULTS

Two patients experienced mild side effects related to venous CO(2) injection. Comparison of cavograms obtained with CO(2) and iodinated contrast-enhanced material showed the caval size to be within 3 mm in all 119 patients. In 116 patients (97.5%), CO(2) cavography was judged to be adequate, and in 115 patients, filters were placed. In three (2.5%) patients, it was necessary to perform iodinated contrast-enhanced cavography before filter deployment. All six cases of venous anomaly and 11 (78.6%) of 14 cases of thrombosis were clearly identified with CO(2) cavography. One filter was maldeployed owing to misinterpretation of the CO(2) cavogram.

CONCLUSION

CO(2) cavography is well tolerated, safe, and adequate for identification of the parameters necessary for filter deployment. It is especially valuable in patients with a history of reaction to iodinated contrast material or renal insufficiency.

Characterization of isolated acidocalcisomes of Trypanosoma cruzi

The acidocalcisome is an acidic calcium store in trypanosomatids with a vacuolar-type proton-pumping pyrophosphatase (V-H(+)-PPase) located in its membrane. In this paper, we describe a new method using iodixanol density gradients for purification of the acidocalcisome from Trypanosoma cruzi epimastigotes. Pyrophosphatase assays indicated that the isolated organelle was at least 60-fold purified compared with the large organelle (10,000 x g) fraction. Assays for other organelles generally indicated no enrichment in the acidocalcisome fraction; glycosomes were concentrated 5-fold. Vanadate-sensitive ATP-driven Ca(2+) uptake (Ca(2+)-ATPase) activity was detectable in the isolated acidocalcisome, but ionophore experiments indicated that it was not acidic. However, when pyrophosphate was added, the organelle acidified, and the rate of Ca(2+) uptake increased. Use of the indicator Oxonol VI showed that V-H(+)-PPase activity generated a membrane potential. Use of sulfate or nitrate in place of chloride in the assay buffer did not affect V-H(+)-PPase activity, but there was less activity with gluconate. Organelle acidification was countered by the chloride/proton symport cycloprogidiosin. No vacuolar H(+)-ATPase activity was detectable in isolated acidocalcisomes. However, immunoblots showed the presence of at least a membrane-bound V-H(+)-ATPase subunit, while experiments employing permeabilized epimastigotes suggested that vacuolar H(+)-ATPase and V-H(+)-PPase activities are present in the same Ca(2+)-containing compartment.

Properties of sperm separated using Percoll and IxaPrep density gradients. A comparison made using CASA, longevity, morphology and the acrosome reaction

Since the withdrawal of Percoll from use in human assisted reproduction techniques in 1996, alternative density gradients have been sought. IxaPrep is one candidate that has low toxicity and can separate spermatozoa. Fractions of spermatozoa from normozoospermic men, separated by Percoll and IxaPrep gradient centrifugation, were assessed for sperm recovery, motility, morphology and the ability to undergo the acrosome reaction. The Percoll fractions had a significantly higher sperm recovery, motile count, rapid motile count, VAP, VSL, and VCL than those obtained using IxaPrep, both immediately after separation and up to 24 h later. In contrast, ALH, level of abnormal sperm morphology and the ability to acrosome react were not statistically different in sperm fractions separated using either gradient forming material.

Kinetic analysis of human immunodeficiency virus type 1 assembly reveals the presence of sequential intermediates

The assembly and budding of lentiviruses, such as human immunodeficiency virus type 1 (HIV-1), are mediated by the Gag protein precursor, but the molecular details of these processes remain poorly defined. In this study, we have combined pulse-chase techniques with density gradient centrifugation to identify, isolate, and characterize sequential kinetic intermediates in the lentivirus assembly process. We show that newly synthesized HIV-1 Gag rapidly forms cytoplasmic protein complexes that are resistant to detergent treatment, sensitive to protease digestion, and degraded intracellularly. A subpopulation of newly synthesized Gag binds membranes within 5 to 10 min and over several hours assembles into membrane-bound complexes of increasing size and/or density that can be resolved on Optiprep density gradients. These complexes likely represent assembly intermediates because they are not observed with assembly-defective Gag mutants and can be chased into extracellular viruslike particles. At steady state, nearly all of the Gag is present as membrane-bound complexes in various stages of assembly. The identification of sequential assembly intermediates provides the first demonstration that HIV-1 particle assembly proceeds via an ordered process. Assembly intermediates should serve as attractive targets for the design of antiviral agents that interfere with the process of particle production.

Comparison of double-contrast CT arthrography image quality with nonionic contrast agents: isotonic dimeric iodixanol 270 mg I/mL and monomeric iohexol 300 mg I/mL

RATIONALE AND OBJECTIVES

The authors evaluated the image quality on delayed CT arthrography images with the use of the nonionic dimeric contrast agent, iodixanol 270 mg I/mL, compared with iohexol 300 mg I/mL.

METHODS

A total of 132 patients with shoulder pain were included in a randomized, parallel, double-blind study. Sixty seven patients received iodixanol and 65 patients received iohexol. Patients underwent two CT-arthrography examinations: the first was performed 20 to 30 minutes after contrast injection and the second, 50 to 70 minutes after contrast injection. Data from 31 patients were excluded from the efficacy analysis. The overall quality of CT arthrography images was graded into four categories: excellent, good, moderate, and bad.

RESULTS

The overall quality of delayed CT arthrography images was significantly better in the iodixanol group (P = 0.001, alpha = 0.05). On the first CT examination, image quality was good or excellent in 88% of the cases in the iodixanol group and in 96.1% in the iohexol group. The results on the delayed CT arthrography examination indicated that image quality was good or excellent in 88% of the cases when iodixanol was used and in 63.5% when iohexol was used.

CONCLUSIONS

The overall quality of delayed images was significantly better with iodixanol than with iohexol.

Assessment of coronary vasomotor function: old and new tools

Atherosclerosis has an impact on the vasomotor reaction of coronary segments to iodinated non-ionic contrast agents. Angiographically normal coronary segments show divergent vasomotor reactions to iodixanol or iopromide according to the presence of, and distance from, a coronary atherosclerotic lesion. The mechanism responsible for the above-mentioned vasomotor effect does not seem to involve flow-mediated vasodilation or endothelial nitric oxide synthesis. On the other hand, a cyclooxygenase product may be, at least in part, responsible for the vasodilating effect of non-ionic agents on epicardial coronary arteries. These findings have potential clinical implications that are herein discussed.

A comparison of ionic versus nonionic contrast medium during primary percutaneous transluminal coronary angioplasty for acute myocardial infarction (GUSTO IIb). Global Use of Strategies to Open Occluded Coronary Arteries in Acute Coronary Syndromes

The clinical impact of contrast medium selection during primary percutaneous transluminal coronary angioplasty for acute myocardial infarction (AMI) has not been studied. We compared the clinical outcomes of patients who received ionic versus nonionic low osmolar contrast medium in the setting of primary percutaneous transluminal coronary angioplasty for AMI in the second Global Use of Strategies to Open Occluded Coronary Arteries in Acute Coronary Syndromes (GUSTO IIb) trial. Univariable and multivariable analyses were performed to assess the relation between contrast medium selection and clinical outcome (death, reinfarction, or refractory ischemia) at 30 days. Although baseline clinical and angiographic characteristics were generally similar between the 2 groups, patients who received ionic, low osmolar contrast were less likely to have been enrolled at a US site (23% vs 43%, p = 0.001) and less likely to have occlusion of the left anterior descending coronary artery (34% vs 47%, p = 0.03) or a history of prior AMI (8% vs 16%, p = 0.02). The triple composite end point of death, reinfarction, or refractory ischemia occurred less frequently in the ionic group, both in the hospital (4.4% vs 11%, p = 0.018) and at 30 days (5.5% vs 11%, p = 0.044). Although the trend favoring ionic contrast persisted, the differences were no longer statistically significant after adjustment for imbalances in baseline characteristics using a risk model developed from the study sample (n = 454, adjusted odds ratio for ionic contrast 0.48 [0.22 to 1.02], p = 0.055), and using a model developed from the entire GUSTO IIb study cohort (n = 12,142, adjusted odds ratio for ionic contrast 0.50 [0.23 to 1.06], p = 0.072). The results of this observational study warrant further elucidation by a randomized study design in this setting.

Regional differences in intestinal spreading and pH recovery and the impact on salmon calcitonin absorption in dogs

PURPOSE

To investigate the regional influence of intestinal spreading and pH recovery on the performance of drug and excipient delivery systems and their impact on the oral absorption of a model peptide drug, salmon calcitonin (sCT), in conscious beagle dogs.

METHODS

Male beagle dogs were surgically prepared with subdermal Intestinal Access Ports (IAP). The catheter from one port was placed in the duodenum and the other in the ileum. Fluoroscopy and Heidelberg pH capsule studies were performed to characterize intestinal spreading and pH recovery, respectively. Three treatments were performed: (1) a radiopaque dye and citric acid (CA) were infused into the intestinal segments, (2) a radiopaque powder capsule containing CA was given orally, and (3) capsules containing CA and sCT were given orally. Regular blood samples were collected and analyzed by radioimmunoassay (RIA) to determine the absorption characteristics of sCT.

RESULTS

Since sCT is an excellent substrate for the pancreatic serine protease trypsin, the rate of degradation of sCT in the GI lumen is dependent upon the regional pH, activity of digestive enzymes and the concentration of sCT at the site of absorption. Fluoroscopy results clearly showed that when the radiopaque dye was infused into the duodenum and capsule disintegration occurred early, there was significant dilution and spreading of the excipients throughout a large section of the upper small intestine (USI). However, when the radiopaque dye was infused into the ileum and capsule disintegration occurred in the lower small intestine (LSI), the excipients moved along as a bolus (i.e., plug). The pH monitoring results were consistent with the fluoroscopy results. The pH dropped only momentarily and rose quickly in the USI consistent with well-stirred mixing kinetics. In the LSI, dilution and spreading were minimal and the drop in pH was greater and persisted for a longer period of time. Plasma levels of sCT were maximal when disintegration occurred in the LSI.

CONCLUSIONS

Since significantly less dilution and spreading occurred in the LSI, the exposure of the intestine to pharmaceutical excipients and sCT was more concentrated resulting in a higher fraction of sCT absorbed. The results of this study demonstrate that intestinal mixing kinetics have a dramatic impact on the ability of pharmaceutical excipients to modulate the oral bioavailability of peptide drugs like sCT.

Segmental and subsegmental pulmonary arteries: evaluation with electron-beam versus spiral CT

PURPOSE

To compare contrast agent-enhanced spiral and electron-beam computed tomography (CT) for the analysis of segmental and subsegmental pulmonary arteries.

MATERIALS AND METHODS

CT angiography of the pulmonary arteries was performed in 56 patients to rule out pulmonary embolism. Electron-beam CT was performed in 28 patients. The other 28 patients underwent spiral CT with comparable scanning protocols. The depiction of segmental and subsegmental arteries was analyzed by three independent readers. The contrast enhancement in the main pulmonary artery was measured in each patient.

RESULTS

Analysis was performed in 1,120 segmental and 2, 240 subsegmental arteries. One segmental (RA7, P =.010) and two subsegmental (LA7b, P =.029; RA6a+b, P =.038) arteries in paracardiac and basal segments of the lung were depicted significantly better with electron-beam CT. There was no statistically significant difference between electron-beam and spiral CT in the total number of analyzable peripheral arteries depicted. The mean contrast enhancement in the main pulmonary artery was 362 HU in electron-beam CT studies versus 248 HU in spiral CT studies.

CONCLUSION

Detailed visualization of peripheral pulmonary arteries is well within the scope of advanced CT techniques. Electron-beam CT has minor advantages in analyzing paracardiac arteries, probably because of reduction of motion artifacts and higher contrast enhancement. Further studies are needed to establish whether electron-beam CT allows a more confident diagnosis of emboli in these vessels.

Size of colorectal liver metastases at abdominal CT: comparison of precontrast and postcontrast studies

PURPOSE

To investigate whether measurements of hepatic metastases from colorectal carcinoma before contrast material administration are significantly different statistically from measurements after contrast material administration.

MATERIALS AND METHODS

Twenty-four patients with hepatic metastases from colorectal carcinoma underwent spiral computed tomography (CT) with 7-mm collimation. The liver was imaged before and in the portal-dominant phase after intravenous contrast material administration. For each scan, one to three discrete liver lesions were selected for measurement (n = 49). Three experienced radiologists performed independent measurements of the selected lesions on both pre- and postcontrast images at a computer workstation. A three-way analysis of variance (ANOVA) was performed: subjects by raters (the three independent radiologists) by pre- or postcontrast status. The dependent variable was the product of bidimensional measurements.

RESULTS

Sixty-seven percent (33 of 49) of the lesions were measured as larger on precontrast images; 33% (16 of 49), as smaller. There was high interrater reliability, with an intraclass correlation coefficient greater than 0.9 ANOVA showed significant subject, rater, and contrast material effects (P < .001) for the largest lesions in each liver. Contrast material status was a significant factor for all lesion sizes (P < .003).

CONCLUSION

On average, hepatic metastases from colorectal carcinoma are significantly smaller after contrast material administration.

Separation of the intracellular secretory compartment of rat liver and isolated rat hepatocytes in a single step using self-generating gradients of iodixanol

A novel method is described for the separation on a single gradient of the major intracellular organelles of the secretory pathway, the Golgi, the smooth endoplasmic reticulum, and the rough endoplasmic reticulum. Total microsomes were prepared from rat liver by differential centrifugation and resuspended in 20% iodixanol. The microsomal suspension was then layered between a 30% iodixanol cushion and a layer of 15% iodixanol and centrifuged in a vertical rotor for 2 h. The microsomes distributed in four visible bands. The gradients were collected by upward displacement and were characterized (i) by determination of UDP galactose-galactosyltransferase (Golgi marker) NADPH-cytochrome c reductase (endoplasmic reticulum marker) and RNA (rough endoplasmic reticulum marker); (ii) by immunoblotting for TGN38 (trans-Golgi marker) and GS28 (cis-Golgi marker) and for protein disulfide isomerase (endoplasmic reticulum lumenal marker); (iii) by determination of the lipid composition; and (iv) by electron microscopy. The results suggest that the top band (density 1.045-1. 090 g/ml), which contains 68% of the galactosyltransferase activity, consists of vesicles derived from the Golgi. The second broad band in the middle of the tube (density 1.130-1.160 g/ml), which contains 54% of the NADPH-cytochrome c reductase activity, consists mainly of vesicles derived from the smooth endoplasmic reticulum, overlapped at the top by a small band of Golgi-derived lamellae. The two bands at the bottom of the tube (density 1.130-1.160 and density 1.180-1. 220 g/ml) appear to contain two subfractions of vesicles derived from the rough endoplasmic reticulum.

Absence of cerebrospinal fluid abnormalities and spinal cord lesions after iotrolan cervical myelography in normal cats: an open placebo-controlled study

Iotrolan (Isovist 300, Schering AG) at a volume of 0.5 ml/kg B.W. was injected into the cerebellomedullary cistern of 12 cats (Isovist group); the same volume of normal saline was injected in four other cats (control group). Two ml of CSF was collected from each anaesthetized cat by cisternal tap immediately before, and 7 and 15 days after, injection. The physical characteristics, specific gravity, total cell count and total protein concentration of each CSF sample were recorded. The cats were euthanized on day 15 immediately after CSF samples and spinal cord specimens had been obtained. Spinal cord histopathology was examined with the aid of light and transmission electron microscopy. The physical characteristics of all the CSF samples were within the reference range. No significant differences were found for CSF specific gravity, total cell count and total protein concentration between the pre-injection samples and those collected 7 and 15 days post-injection in both groups; no spinal cord lesions were detected in histopathology.

Liver metastases from melanoma: detection with multiphasic contrast-enhanced CT

PURPOSE

To assess the clinical utility of multiphasic computed tomography (CT) of the liver in patients with metastatic melanoma.

MATERIALS AND METHODS

Nonenhanced and biphasic hepatic CT examinations were performed in 28 patients with metastatic melanoma, and liver lesion conspicuity was graded. CT studies in 20 patients met the eligibility criteria, and 13 patients had liver lesions.

RESULTS

A total of 57 liver lesions were seen on CT studies: 48 on hepatic arterial phase images, 49 on portal venous phase phase images, and 30 on delayed phase images. Of eight lesions overlooked on portal venous phase images, six were seen on nonenhanced images, and six were seen on arterial phase images. Twenty-eight lesions were graded as more conspicuous on portal venous phase images; 10 were graded as more conspicuous on arterial phase images.

CONCLUSION

CT images obtained only during the portal venous phase would have resulted in eight (14%) overlooked lesions, which implies that more than one phase is needed for hepatic CT in patients with malignant melanoma. The combination of nonenhanced and portal venous phase CT was as effective as the combination of arterial and portal venous phase CT in these patients. Delayed phase CT did not improve lesion detection either alone or in combination with CT at other phases.

Purification and protein composition of PM2, the first lipid-containing bacterial virus to be isolated

The marine, icosahedral bacteriophage PM2 was isolated in the late 1960s. It was the first phage for which lipids were firmly demonstrated to be part of the virion structure and it has been classified as the type organism of the Corticoviridae family. The host, Pseudoalteromonas espejiana BAL-31, belongs to a common group of marine bacteria. We developed a purification method producing virions with specific infectivity approximately as high as that of the lipid-containing phages PRD1 and &phi;6. The sensitivity of the virus to normally used purification media such as those containing sucrose is demonstrated. We also present an alternative host, a pseudoalteromonad, that allows enhanced purification of the virus under reduced salt conditions. We show, using N-terminal amino acid sequencing and comparison with the genomic sequence, that there are at least eight structural proteins in the infectious virus.

Comparison of iodixanol and iohexol in renal impairment

Iodixanol (Visipaque, Nycomed, Oslo, Norway) is an iodinated contrast medium in the form of a non-ionic dimer which is iso-osmolar with plasma at all iodine concentrations. There is little evidence regarding its renal tolerance in renal impairment. We therefore undertook a prospective randomized comparison of iodixanol and the non-ionic monomer iohexol (Omnipaque, Nycomed, Oslo, Norway). The serum creatinine was measured pre- and post-angiography in a series of in-patients to establish whether there was any clinically detectable evidence of superiority of iodixanol over iohexol in this high risk group. 8/54 (15%) patients in the iodixanol group had a rise in creatinine of > 10% in the week following angiography compared with 15/48 (31%) in the iohexol group (p < 0.05). The creatinine rise was positively correlated with the dose of both contrast media. These results suggest that iodixanol may be slightly less nephrotoxic than iohexol.

[Indirect lymphography--possibilities and limits of roentgen diagnosis of the lymphatic system]

Indirect lymphangiography enables to opacify peripheral lymph-collectors. In case of lymph valve insufficiency and dermal back flow also small skin lymphatics can be visualized. Indirect lymphangiography showed various new lymphatic patterns in different kinds of leg oedema. Specificity of 89% and sensitivity of 97% recommends the method as a good diagnostic tool for diagnosis of lymphoedema in a suspected clinical situation. Indirect lymphangiography is not able to opacify proximal or central lymphcollectors and lymph nodes.

Digital subtraction angiography of the abdominal aorta and lower extremities: carbon dioxide versus iodinated contrast material

PURPOSE

To compare the diagnostic value of carbon dioxide to that of iodinated contrast material for digital subtraction angiography of the abdominal aorta and lower extremities.

MATERIALS AND METHODS

Thirty-five patients underwent comparative CO2 and iodinated contrast material arteriography of the abdominal aorta and lower extremities. For each contrast study, three independent observers evaluated the degree of opacification and percentage of stenosis of each vessel, the degree of certainty of their observations, and the overall quality of the study. Data of CO2 and iodinated studies were compared using analysis of variance for repeated measures. Interobserver and intertechnique agreements were estimated with Cohen's kappa and intraclass correlation coefficient.

RESULTS

Iodine-based vascular opacification was superior to that with CO2 in the central and distal arteries (P = .02). The degree of certainty and overall quality score were higher for iodine than for CO2-based contrast studies (P = .00001). The interobserver agreement for categorizing stenoses was higher for iodine as compared to CO2-based angiography. No significant difference was observed between the mean stenosis values obtained with CO2 and iodine-based angiography in any segment. Intraclass correlation coefficient demonstrated a high degree of convergence of the two techniques for assessing the percentage of stenosis.

CONCLUSION

CO2 can be used as an alternative to iodinated contrast material for obtaining arteriograms of the abdominal aorta and lower extremities for investigating atherosclerotic disease.

Comparison of iodixanol 270 with iohexol 300 in infrapopliteal arteriography. Digital densitometric analysis of angiographic opacification

PURPOSE

To compare iodixanol 270 mg I/ml with iohexol 300 mg I/ml in infrapopliteal arteriography by measuring digital densitometric vessel opacification and by visually assessing angiographic enhancement.

MATERIAL AND METHODS

In a double-blind, dual-balanced, 4-sequence cross-over design, 50 claudicant patients received two contrast media injections (10 min interval) in the superficial femoral artery. Digital angiography was performed at 8 frames/s and time-density curves with a circular region of interest over a distal calf artery were generated. A mixed, linear model was used to identify effects influencing the density measurements. Subjective evaluation of the image quality was made independently by two observers.

RESULTS

No statistically significant difference between the contrast media was revealed in the analysis of the densitometric measurements (p=0.14) nor in the subjective visual evaluation (p=0.74). However, the mean density at the time of maximum opacification was higher after the first injection than that after the second injection (p=0.02). There was a tendency towards lower intensity of warmth during injection of iodixanol 270 than during injection of iohexol 300.

CONCLUSION

In patients with severe occlusive atherosclerotic disease, iodixanol yielded the same image quality as iohexol in infrapopliteal arteriography, in spite of the 30 mg I/ml lower iodine concentration.

Percutaneous biopsy of a posterior mediastinal mass through an extrapleural window created with dilute contrast

Extrapleural administration of dilute contrast was used to facilitate biopsy of a posterior mediastinal mass.