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R Bares

Publications and source records attributed to R Bares.

70 records · Page 4Linked to original sources
PubMed1993

Quantitative analysis of anti-CEA antibody accumulation in human colorectal carcinomas.

In order to obtain quantitative data on intratumoral antibody accumulation we analyzed resected colorectal adenocarcinomas of 25 patients who had undergone immunoscintigraphy 4-14 days earlier. All had been injected with 0.5-1.0 mg intact anti-CEA antibody (BW 431/26) labelled with 70-80 MBq131I. Correlation of tissue radioactivity concentrations with tumor characteristics revealed significantly higher values in necrotic compared to viable as well as in CEA-positive compared to CEA-negative viable tumor tissue indicating action of both specific and unspecific uptake mechanisms. In contrast, diagnostic results of immunoscintigraphy were influenced by tumor size only. 11 of 12 false-negative findings were obtained in tumors < 4 cm in diameter. Since ex-vivo scintigraphy of resected specimens correctly visualized all but one of these lesions, it is concluded that technical limitations of scintigraphy are the main cause of negative results of radioimmunoimaging with 131I-labelled antibodies.

Adenocarcinoma↗
PubMed1992

The radiation dose to surgical personnel during intraoperative radioimmunoscintimetry.

To estimate the radiation exposure to surgical personnel caused by intraoperative radioimmunoscintimetry, we measured dose rates at different distances from patients who had been injected with 950 MBq technetium-99m-labelled intact carcinoembryonic antigen (CEA)-specific antibodies (Szintimun CEA, Behring AG Marburg, FRG) for immunoscintigraphy 24 h earlier. At 0.05 m (corresponding to working positions during surgery) we found 2.0-16.0 microSv h-1 (average 6.4), which is similar to results for nuclear medicine staff. Thus, if radioimmunoscintimetry is to become a routine procedure, according to national regulations in some countries of the European Communities surgical personnel might be regarded as professionally exposed to radiation.

Colorectal Neoplasms↗
PubMed1991

Pharmacokinetics and pharmacodynamics of cisapride in patients undergoing hemodialysis.

Twenty-two patients who were receiving hemodialysis were studied in three groups of eight subjects each to assess the pharmacokinetics during the dialysis-free interval and during hemodialysis treatment and to assess the pharmacodynamics of cisapride. Cisapride and its metabolite norcisapride were measured by use of HPLC and gas chromatography, respectively. The pharmacodynamic effect of cisapride was measured by means of radionuclide gastric emptying. After a single oral dose of 20 mg the terminal half-life of cisapride was 9.6 +/- 3.3 hours, the volume of distribution was 4.8 +/- 3.3 L/kg, the total oral plasma clearance was 380 +/- 161 ml/min, the area under the curve was 1024 +/- 447 ng.hr/ml (mean +/- SD). Norcisapride only could be detected in the dialysate (0.36 +/- 0.067 mg) and was eliminated by a hemodialysis clearance of 34.7 +/- 7.9 ml/min. Cisapride reduced gastric retention from 77.6% +/- 21.1% to 43.7% +/- 18.2% of maximum filling (40 minutes after meals) and normalized the abnormal gastric emptying time in patients receiving dialysis. Cisapride dosage adjustment or substitution after hemodialysis is not necessary.

Adult↗
PubMed1991

[The effective half-life of 131I during the treatment of autonomous thyroid disease with radioiodine].

In order to compute effective half-life of 131I after application of therapeutic doses (Teff), the time course of whole-body radioactivity was evaluated retrospectively in 115 patients with benign thyroid diseases (multinodular autonomous adenoma, solitary autonomous adenoma or Graves' disease). Because of a large overlap of Teff in the various diseases analyzed, courses of all patients who did (group Ts, 24 cases) or did not (group kTs, 91 cases) receive antithyroid drugs during therapy were summarized. In group Ts a mean Teff of 5.0 +/- 0.9 d was found which was significantly (p less than 0.01) lower than the mean Teff of 6.3 +/- 0.9 d in group kTs. We believe that the mean Teff is a practical alternative in radioiodine dosimetry if an exact determination of Teff cannot be performed because of shortage of time.

Adenoma↗
PubMed1990

[Increased bile acid retention in biliodigestive Roux-Y anastomosis in animal experiment].

In an experimental study on 65 rats the influence of different Roux-Y biliary anastomoses on the enterohepatic bile acid circulation was investigated. Long (10 cm) and short (3 cm) isoperistaltic and long (10 cm) anisoperistaltic Roux-Y loops were studied and compared to sham-operated controls. 75-SeHCAT a y-labeled synthetic bile acid was used for assessment of enterohepatic circulation. Hepatic excretion and enteric bile flow was investigated by 99m-Tc-HIDA. Intestinal transit time was evaluated by 51-Cr-EDTA an inert marker of intestinal contents. Animals with biliary anastomoses showed an increased retention of the synthetic bile acid 75-SeHCAT compared to the controls. Highest retention values were found in animals with anisoperistaltic loops (t1/2 = 98.6 h). Isoperistaltic loops showed uniform values independently of the length of the Roux-limb (t1/2 = 59.8 h resp. 59.3 h). Differences to the controls (t1/2 = 42.6 h) were highly significant (p less than 0.001). In the 99m-Tc-HIDA hepatic excretion into the connected small bowel was normal in all groups. But in rats with biliary anastomoses a marked stasis of the 99m-Tc-HIDA in the Roux-Y loop was apparent. Bowel transit time tested by 51-Cr-EDTA showed comparable results in all groups without significant differences. The results demonstrate an increased bile acid retention in Roux-Y biliary anastomoses. An alteration of the enterohepatic circulation due to stasis in the Roux-Y limb seems to be the underlying mechanism.

Anastomosis, Roux-en-Y↗
PubMed1990

Multi-centre immunoscintigraphic study using indium-111-labelled CEA-specific and/or 19-9 monoclonal antibody F(ab')2 fragments.

Six European nuclear medicine centres performed immunoscintigraphy first retrospectively in 34 patients using indium-111-labelled carcinoembryonic antigen (CEA)-specific and/or 19-9 F(ab')2 fragments. Results for sensitivity and specificity in tumour sites were 94% and 87%, respectively, for the pelvis and 73% and 100% for the extrahepatic abdomen. A second prospective series concerned 58 other patients previously operated on for colorectal adenocarcinoma (27 colon, 31 rectum). Two-thirds of these patients had a suspected recurrence signalled by an isolated rise in tumour markers, and 46 patients examined by immunoscintigraphy, X-ray computed tomography and ultrasonography were found to have a recurrence (a total of 62 tumour sites). Sensitivity and specificity with immunoscintigraphy were 90% and 97%, respectively, for the pelvis and 62% and 95% for the extrahepatic abdomen. For 29 patients injected with CEA-specific fragments, sensitivity was 90% and specificity 94% for the pelvis. For 25 patients injected with 19-9 fragments, pelvic sensitivity and specificity were 80% and 100%, respectively, whereas sensitivity for the extrahepatic abdomen was only 29% since several cases of peritoneal carcinosis were not visualized. In the prospective series, comparison of the three imaging techniques for all tumour sites (including liver and in 5 cases thorax) gave a sensitivity and specificity of 82% and 91%, respectively, for immunoscintigraphy, 52% and 95% for X-ray computed tomography and 59% and 100% for ultrasonography. These results thus confirm the advantage of using 111In-labelled CEA-specific or 19-9 to visualize and localize recurrences of colorectal cancer.

Adenocarcinoma↗
PubMed1990

Bile acid retention after Roux-en-Y biliary reconstruction demonstrated by tauro-23-(75Se)selena-25-homocholic acid. An experimental animal study.

In this study of 65 laboratory rats the influence of biliary Roux-en-Y anastomosis on the enterohepatic circulation was investigated. Three different types of Roux-en-Y limbs were studied and compared with sham-operated controls. To collect information about the influence of the length and motility of the Roux limb, 10-cm and 3-cm isoperistaltic Roux segments and 10-cm anisoperistaltic Roux limbs were investigated. 75SeHCAT, a tau-labelled synthetic bile acid, was used for assessment of enterohepatic circulation. Intestinal transit time was evaluated by measuring the decrease of whole-body counts of 51Cr-labelled ethylenediamintetraacetic acid (EDTA), an inert marker of intraluminal contents. 99mTc-labelled dimethyl-iminodiacetic acid (HIDA) was used to detect possible alterations of bile flow. 75SeHCAT results showed marked retention of bile acids in all Roux-en-Y animals compared with controls. Results of short and long Roux limbs did not differ significantly from each other (t1/2 10 cm, 59.8 h; 3 cm, 59.3 h; control, 42.6 h; p less than or equal to 0.001). The anisoperistaltic Roux limbs showed prolonged retention even when compared with isoperistaltic limbs (t1/2 98.6 h; p less than or equal to 0.001). 51Cr-EDTA results did not show significant differences between all groups. 99mTc-HIDA showed undelayed excretion in all animals but increase of radioactivity at the site of the Roux-en-Y enteroanastomosis, indicating marked stasis in the biliodigestive Roux limb. The results demonstrate the impact of biliary Roux-en-Y anastomosis on bile acid retention due to stasis in the defunctioning jejunal segment.

Anastomosis, Roux-en-Y↗
PubMed1990

[Postcholecystectomy syndrome--still a current argument today?].

The "postcholecystectomy syndrome" was originally defined by Pribram as a pure functional disturbance after cholecystectomy. Today it has become a melting pot of various postoperative syndromes of mostly obscure origin. It's incidence is said to be 26-40%, but surgically treatable lesions of the biliary system amount only 1.5%. Functional consequences for biliary excretion are rare because the loss of the gallbladder reservoir is substituted in part by the biliary tree.

Bile↗
PubMed1989

Radioimmunoscintigraphy with 111In labelled monoclonal antibody fragments (F(ab')2 BW 431/31) against CEA: radiolabelling, antibody kinetics and distribution, findings in tumour and non-tumour patients.

Forty seven patients with suspected malignant disease (mainly colorectal cancer) were studied with 111In labelled F(ab')2 fragments of an anti-CEA monoclonal antibody (BW 431/31). The kinetic data revealed a long whole body retention of the label (62% after 4 days) and a rapid blood clearance (77% within 24 h, 89% within 48 h) leading to an early positive tumour contrast 24 h p.i. and optimal scintigrams 48 h p.i. Diagnostic results were promising in local recurrences of colorectal cancer (8/10 positive = 80%) though false positive findings in patients with inflammatory bowel disease occurred probably due to cross-reaction with a human granulocyte antigen. Liver metastases and tumours neighbouring liver and spleen were often missed (10/27 = 37%) because of high nonspecific uptake in these organs. Thus BW 431/31 proved to be a suitable compound for radioimmunodetection, however, further improvements to optimize tumour affinity and specificity of the antibody are mandatory.

Aged↗
PubMed1989

[Clinical significance of immunoscintigraphy for the diagnosis and treatment of gastrointestinal malignant tumors].

Eighty-one immunoscintigraphy (IS) studies in 80 patients with gastrointestinal malignancies were re-evaluated retrospectively to analyze accuracy and clinical impact of the IS findings. Selection of patients was based upon complete diagnostic records and a clinical follow-up of at least 6 months. The 3 antibody preparations used (99m-Tc labelled complete anti-CEA antibodies (BW 431/26), 111-In labelled F(ab')2-fragments against CEA (BW 431/31), and a mixture of 131-I labelled F(ab')2-fragments against CEA and CA 19-9 (IMACIS-1] yielded equal diagnostic sensitivities (65%, range 60-78%) except for liver metastases. These were preferably detected by the 131-I labelled compound. Best results were gained in local recurrencies of gastrointestinal cancer (12/15 true positive = 80%). Among these were 3 out of the 4 lesions which had been exclusively recognized by IS. Thus IS should be applied in patients with suggested local recurrencies and inconclusive outcome of routine diagnostic workup. A widespread and frequent use of IS (e.g. screening of metastases) cannot be advocated since diagnostic results were not convincing and the immunologic risks of IS (development of human anti-mouse antibodies) are still under discussion.

Antibodies, Monoclonal↗
PubMed1988

Myocardial kinetics of 99Tcm hexakis-(2-methoxy-isobutyl-isonitrile) (HMIBI) in patients with coronary heart disease: a comparative study versus 201Tl with SPECT.

In 15 patients with coronary heart disease, 74 MBq 201Tl (A) and 240 MBq 99Tcm HMIBI (B) were injected during exercise on separate days and SPECT imaging was applied. In (B) a consecutive second injection was given with an identical dose 3 h later (at rest) and net rest distribution was obtained from a subtraction technique. From polar, target-like ROIs, data were computed to compare regional vitality, wash-out and wash-out corrected redistribution. Myocardial wash-out, in contrast to 201Tl, was found to be 20% for 99Tcm independent of the regional myocardial state. Since no considerable redistribution occurred, myocardial distribution of 99Tcm HMIBI remained rather constant for 3 h, resulting in a maximum myocardium to lung ration of about 5. After the second injection, redistribution revealed the same results as in the 201Tl targets. From regional exercise to rest ratios a 'perfusion reserve' was determined which was 2.1 in normal and 1.3 in myocardial areas with defects. Myocardial defect uptake and defect size were nearly identical, yielding agreement in 97% of the myocardial segments. We conclude that 99Tcm HMIBI is a most powerful myocardial imaging agent. The final routine protocol, however, is as yet not established.

Coronary Disease↗
PubMed1987

[Radioimmunoscintigraphy using SPECT: methodology, problems and clinical experiences].

Radioimmunoscintigraphy (RIS) with 111In-and 131I-labelled monoclonal antibodies (MAbs) against CEA and/or CA 19-9 was performed in 83 patients with various gastrointestinal carcinomas. A total of 276 body regions could be examined. The results of planar scintigraphy and SPECT were compared intraindividually. Using 111In-labelled MAbs the sensitivity of RIS was significantly improved by SPECT (88.9 vs. 52.4% with planar scintigraphy, p less than 0.01). For 131I-labelled MAbs the effect was smaller (83.9 vs. 65.6% with planar scintigraphy, n.s.). This finding can be explained by different kinetics and biodistribution of the used MAb preparations. 111In-labelled MAbs with long whole-body retention and rapid blood clearance reveal ideal qualities for SPECT; on the other hand, the short whole-body retention of 131I-labelled MAbs leads to small count rates and therefore long counting times that make delayed SPECT unsuitable in clinical practice.

Antibodies, Monoclonal↗
PubMedDate not supplied

Comparison of 18FDG-PET with CT scans in the evaluation of patients with residual and recurrent Hodgkin's lymphoma.

The reliable assessment of residual masses after treatment as well as of new lesions suspected for relapse remains a diagnostic problem in patients with Hodgkin's disease (HD). The current study compares the results obtained by CT scan to FDG-PET imaging in a blind analysis with respect to the viability of residual masses and in case of suspected relapse. Between 1/94 and 10/99, 47 comparisons of PET and corresponding CT scans - 26 comparisons in 24 patients with residual tumors and 21 comparisons in 20 patients with suspected relapse of HD - were evaluated by independent reviewers blinded to he results of each other. Patients with primary diagnosis had been treated within trials of the German HD Trial study group. Relapsed patients received intensified salvage chemotherapy regimens. PET was assessed visually and by quantifying glucose uptake (SUV). Changes in size of tumor lesions as well as contrast medium enhancement served as criteria for assessment by CT scans. Results were validated either by histologic examination of a resected mass or biopsy (n=17) or by a clinical follow-up over 6 months following treatment (n=30). In 26 cases with residual lesions FDG-PET showed an increased tracer uptake in 8, 7 of which were true positive (TP) and 1 false positive (FP). Eighteen cases were classified as being negative (no viable HD), 17 true negative (TN) and 1 FN. In the blinded reading of the corresponding CT scans, 10 cases with residual lesions were considered to contain vital lymphoma (2 TP, 8 FP). Sixteen CT scans were classified as negative (10 TP, 6 FN). The resulting sensitivity and specificity of PET were 87.5% and 94.4% in contrast to only 25% and 56% for CT scans. The positive and negative predictive values of PET and CT scans were 87.5% and 94.4% and 20% and 62.5%, respectively. In patients with suspected relapse, sensitivity and positive predictive value for the diagnosis of the relapse were 100% and 86%, respectively, yielding the same results for both methods. FDG-PET performed in HD patients with residual masses appears to offer important additional information regarding the presence of viable HD in these residual lesions. In patients with suspected relapse of HD, FDG-PET seems not to offer any information over CT scans. Using SUVs is not superior to visual assessment of PET alone.

Adult↗