[The problem of the light source in photoelectric colorimeters].
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Colorimetry↗
Biomedical subjects
J Link
Publications and source records attributed to J Link.
Determination of binding constants of diabodies directed against prostate-specific antigen using electrochemiluminescence-based immunoassays.
Two diabody molecules directed against the prostate-specific antigen (PSA) were generated from a combinatorial phage display library. The C-termini of diabodies incorporated the FLAG peptide epitope (P008D diabody) or the myc epitope (P001D). Both diabodies have the same antigen-binding site. Equilibrium-binding constants of these molecules were determined in two immunoassays using the ORIGEN detection system based on electrochemiluminescence. The binding of diabodies to biotinylated PSA was detected with either polyclonal antimouse Fab F(ab')2 or a monoclonal antibody directed against the FLAG epitope. Both detecting antibody preparations were covalently labeled with a ruthenium (II) tris (bipyridyl) moiety, Ru(bpy)3(2+), which allows quantification via an electrochemically triggered light reaction in an ORIGEN analyzer. The binding constants obtained by Scatchard analysis of non-linear curve fitting calculations from electrochemiluminescence immunoassays were compared with data derived from kinetic-binding studies using the BIAcore technology based on surface plasmon resonance. Depending on the detecting antibody, the dissociation constants KD determined at equilibrium with the ORIGEN technology are between 0.1 and 0.4 nM for both diabodies. From the kinetic constants kon and koff measured with the BIAcore instrument KD was calculated to be 0.2 nM for P001D and 0.6 nM for P008D. It is concluded that these two very different methods generate comparable affinity data for the diabodies.
Animals↗
Contrast-enhanced, K-space-centered, breath-hold MR angiography of the renal arteries and the abdominal aorta.
The purpose of this study was to evaluate the capability of contrast-enhanced breath-hold fast imaging with steady-state precession (FISP) three-dimensional MR angiography (MRA) to detect stenotic lesions of the abdominal aorta, the renal arteries, and the iliac arteries by using a K-space-centered 20-ml gadolinium-diethylene pentaacetic acid (Gd-DTPA) bolus. Fifty patients were studied before conventional x-ray angiography. Contrast-enhanced breath-hold FISP three-dimensional MRA was applied in the coronal view, centered at the renal arteries. Twenty ml of Gd-DTPA was used in all subjects. A test bolus was applied to determine the injection time for the K-space-centered bolus injection. Of 300 segments, 284 segments were classified correctly, 11 were overestimated, and five were underestimated. Sensitivity was 98%, specificity was 96%, positive predictive value was 96%, negative predictive value was 98%, and accuracy was 97%. Of the 50 patients studied, 43 were staged correctly. No venous overlay was seen in 31 patients; partial overlay was seen in 16 patients, and venous structure overlay obscuring arterial anatomy was found in two patients. Six of nine accessory renal arteries could be identified by MRA. Intraobserver variability was .94. This study has shown the ability of contrast-enhanced breath-hold FISP three-dimensional MRA to detect and grade vascular lesions in the abdominal aorta and the renal arteries. The method may serve as a screening tool in the future.
Adult↗
Perivascular inflammatory reaction after percutaneous placement of covered stents.
A 52-year-old woman with an extensive superficial femoral artery occlusion was treated with percutaneous transluminal angioplasty. Because of extensive dissections, two covered stents were placed percutaneously. The intervention was successful with respect to vessel patency, but local pain and fever developed 5 hr after the intervention. Swelling of the thigh occurred, but deep venous thrombosis was excluded. MRI revealed pronounced soft-tissue edema in the adductor canal that persisted for 4 weeks. The fever responded to antiinflammatory medication, but the pain remained for 4 weeks. The vessel was patent at the last follow-up, 8 weeks after graft placement. Soft-tissue edema after percutaneous placement of covered stents has been reported previously. The cause of the inflammatory reaction is unclear.
Aortic Dissection↗
Rheolytic thrombectomy of an acutely thrombosed transjugular intrahepatic portosystemic stent shunt.
As an alternative to chemical thrombolysis, an acutely occluded transjugular intrahepatic portosystemic stent shunt in a 72-year-old woman was successfully recanalized using a 5 Fr rheolytic catheter system. No adjunctive thrombectomy treatment was necessary. The underlying stenotic leason was treated with percutaneous transluminal angioplasty and a Palmaz stent. Immediately after the intervention optimal shunt flow was achieved. Ascites vanished within a few days and no further bleeding complications appeared.
Aged↗
Selection and rapid purification of murine antibody fragments that bind a transition-state analog by phage display.
Functional antibody fragments may be displayed on the surface of filamentous bacteriophage by introducing variable region genes into the viral genome at a gene encoding a viral coat protein. "Phage display" enables the isolation of antibody genes from large libraries according to the binding specificities they encode. We have constructed a new phage-display vector encoding a polyhistidine tag that has been used for rapid purification of soluble antibody fragments. An antibody library derived from immunized mice was cloned into this vector. This library was panned against the transition state analog RT3, and a high proportion of binders isolated after two rounds of panning. PCR analysis revealed that there were 24 different pattern groups. Sequencing of 15 clones within the major pattern group revealed 10 related clones with a range of point mutations. Thus, phage display can provide a large diverse repertoire of candidate catalytic antibodies based on TSA selection and screening.
Animals↗
Percutaneous endoluminal stent and stent-graft placement for the treatment of femoropopliteal aneurysms: early experience.
PURPOSE: To determine the efficacy of percutaneous endoluminal stents and stent-grafts for the treatment of isolated femoropopliteal aneurysms. METHODS: Seven men (age 51-69 years) with femoropopliteal occlusions (n = 6) related to aneurysms and a patent femoropopliteal aneurysm (n = 1) were treated percutaneously. In two patients uncovered Wallstents and in five patients polyester-covered nitinol stents were implanted. Assessment was performed with Doppler ultrasound and duplex ultrasonography 24 hr, 1, 3, 6, 12, and 24 months after the intervention. Additionally, intraarterial angiography was performed at 6 months. RESULTS: Stent placement succeeded in all cases. No immediate adjunctive surgical treatment was necessary. Ankle-brachial index (ABI) improved from 0.29 +/- 0. 29 (SD) before to 0.78 +/- 0.23 (SD) 24 hr after the intervention. One patient was lost to follow-up. Stent-graft occlusion occurred in four patients: after 2 days (n = 1), 1 month (n = 2), and 3 months (n = 1). One of the patients, whose stent occluded at 1 month, underwent successful recanalization with local fibrinolysis therapy. Three of the seven, all with three-vessel run-off, demonstrated patency of the stent, which was assessed by duplex ultrasonography at 29, 31, and 34 months. Breaking of the stent struts or significant stent migration was not observed. CONCLUSIONS: These results in a small number of patients warrant further investigation to evaluate the role of percutaneous stents in femoropopliteal aneurysms. Until further data of clinical studies are available, this method cannot be recommended, and it cannot replace surgical treatment.
Aged↗
Prospective assessment of carotid bifurcation disease with spiral CT angiography in surface shaded display (SSD)-technique.
PURPOSE: To decide, whether spiral CT-angiography (CTA) in surface display (SSD)-technique is suitable for accurate quantification of carotid artery stenoses. MATERIAL AND METHODS: Forty-four patients (25 male, 19 females) with a total of 80 symptomatic carotid artery were studied prospectively with selective cerebral angiography and spiral CTA in SSD-technique. The degree of stenosis was determined according to the NASCET-study. RESULTS: Assessment of the degree of stenoses with CTA and angiography was the same in 36% of mild stenoses, in 64% of moderate stenoses, in 68% of severe stenoses, and in 95% of the occluded internal carotid arteries. Overall, CTA in SSD-technique showed equivalent results as selective cerebral angiography in 65% of all cases. CONCLUSION: Spiral CTA in SSD-technique is inferior to selective cerebral angiography. Calcified plaques, vessel opacification and thresholding influence the most grading of stenosis.
Adult↗
Intracerebral hemorrhage as a late complication after CNS treatment of childhood lymphoma.
Since the majority of children with acute leukemia and lymphoma are long-term survivors, more attention is directed towards late sequelae of therapy. Intracerebral hemorrhage after treatment of central nervous system (CNS) neoplasia in childhood is a very rare event. A seven and a half-year-old boy was admitted to our hospital because of acute third nerve palsy. Three years and eight months before the patient had been treated for a mediastinal T-cell non Hodgkin's lymphoma (T-NHL) with CNS involvement by combined chemo-radiotherapy. Recurrent disease was excluded, but intracerebral hemorrhage in the tectal area was demonstrated by repeated magnetic resonance imaging. Symptoms of incomplete oculomotor paresis improved spontaneously with conservative therapy. Intracerebral hemorrhage may occur as a rare complication in children with malignant CNS disease even years after treatment with combined chemo-radiotherapy.
Central Nervous System Neoplasms↗
Lower extremity occlusive disease: diagnostic imaging with a combination of cardiac-gated 2D phase-contrast and cardiac-gated 2D time-of-flight MRA.
PURPOSE: The goal of this work was to test the ability of a combination of 2D phase-contrast MR angiography (2D-PC-MRA) and triggered 2D time-of-flight MRA (2D-TOF-MRA) in comparison to intraarterial digital subtraction angiography (DSA) to correctly diagnose the location and shape of occlusive lesions in the iliac and femoral arteries and to determine whether 2D-TOF-MRA is helpful to clarify questionable lesions demonstrated by 2D-PC-MRA. METHODS: In 50 patients with claudication, 2D-PC-MRA was performed in three consecutive coronal positions from the aortic bifurcation to below the trifurcation. Axial 2D-TOF-MRA was performed additionally at the site of detected lesions of >50% and lesions in doubt to obtain more precise information about the stenosis. Lesions were classified as follows: low grade occlusion, <50%; high grade occlusion, >50%. MRA was performed within 24 h of a DSA examination. RESULTS: In all patients, the arterial tree from the aortic bifurcation to the trifurcation could be visualized. One hundred twelve lesions were detected by MRA. Sensitivity was 96% and specificity was 92%. Sixty-two lesions were classified as high grade occlusion and reevaluated. In this category, sensitivity was 100% and specificity was 96%. CONCLUSION: The combination of 2D-PC-MRA with triggered 2D-TOF-MRA detects stenotic lesions in the lower extremity arterial system with high sensitivity and specificity.
Adult↗
Self-monitoring of blood glucose: how accurate are children with diabetes at reading chemstrip bG?
Accuracy of self-monitoring of blood glucose (SMBG) using Chemstrip bG (Bio-Dynamics, Indianapolis, Indiana) was studied in 90 randomly selected children with insulin-dependent diabetes mellitus (IDDM). For 28 children (mean age 8.3 +/- 3.6 yr) a parent routinely read the Chemstrip at home. The remaining 62 children (mean age 13.7 +/- 2.8 yr) read the Chemstrip themselves. Each child or parent analyzed 20 capillary blood samples using Chemstrips and answered a questionnaire on SMBG. The accuracy of SMBG of the group was high (mean correlation coefficient = 0.89 +/- 0.05), but consistency of measurement was variable (mean standard deviation = 1.90 +/- 0.57) and there was a general tendency to underread Chemstrips (mean y-intercept = 1.05 +/- 1.48; mean slope = 0.80 +/- 0.17). For each subject, 0-65% (mean of 34%) of readings were within 10% of the laboratory measurement, and 17-100% (mean 68%) within 20%. These results indicate that most subjects were fairly accurate in reading Chemstrips; however, analysis of accuracy is useful in identifying individuals who are inaccurate or inconsistent in SMBG. Continuing supervision of SMBG is necessary in children with IDDM.
Adolescent↗