99MTc-Dextran-Antibody Conjugates : Labelling procedures

Dextran forms stable chelates with ^99mTc, a radionuclide with ideal properties for planar scintigraphic and tomographic imaging. This study investigates some of the factors of importance to the formation of ^99mTc-dextran. The complex was used for the technetium labelling of a monoclonal antibody. Two radiolabelling methods were studied: direct dextran labelling with the reductant dissolved in HCl and labelling via a weak 'transfer' chelator (tartaric acid) with the reductant dissolved in ethanol. Different conditions during the labelling reaction were studied. Finally, dextran was coupled to a monoclonal anticytokeratin antibody and the conjugate was subsequently radiolabeled with ^99mTc. Gel filtration (GFR) and thin layer chromatography (TLC) were compared as methods for estimation of the labelling efficiency. When using 10-500μM of Ugand, 5-100μM SnCl₂ with 10-500 MBq of technetium at pH7 incubated for 10-15 min, the radiolabelling seemed optimal (70-75% labelling efficiency). It was found that 100 μM tartaric acid used as a weak intermediate chelator with SnCl₂ dissolved in ethanol improved the reproducibility of the labelling. The labelling efficiency was not affected by either the presence of oxygen or the addition of an oxygen scavenger during the labelling incubation. In general, TLC showed higher labelling efficiencies than GFR, indicating inadequate separation of the different moieties.     

An ELISA technique for quantitation of human xenoantibodies binding to pig cells: Application in patients with pig kidneys extracorporeally connected to the circulation

ABSTRACT: A quantitative ELISA technique for determination of human anti-pig xenoantibody number in serum samples has been established using pig lymphocytes and pig/rabbit erythrocytes as target cells and a pool of serum from human blood group AB donors. The number of low affinity antibodies binding to the cells was determined by quantitation following the use of aqueous washing of the cells and separation of bound and unbound antibodies with the phthalate oil method. The efficiency of different soluble Galal-3Gal-terminating di- and tri-saccharides to inhibit antibody binding was tested and found to vary between 70–90% at a saccharide concentration of 10 mg/ml. The assay was used to evaluate the antibody changes in two patients who, after plasmapheresis treatments, had pig kidneys extracorporeally connected to their blood circulation. The number of anti-pig IgM/IgG antibodies bound to each pig lymphocyte were reduced from 5,600/13,200 to 1,300/3,100 in patient 1 and from 1,200/6,500 to 500/2,100 in patient 2 by three consecutive daily plasmapheresis treatments. Although the lymphocytotoxic titers were reduced to very low levels, the antibody numbers still present in the blood of patient 1 caused a hyperacute rejection of the pig kidney. However, the antibody levels in patient 2 did not cause rejection of this kidney during 15 min perfusion time. A strong anti-pig antibody response 3 weeks after the perfusion experiment was found in patient 1 as shown by 27,600/245,300 IgM/IgG molecules bound to pig lymphocytes corresponding to an increase of lymphocytotoxic titer from 8 to 512. The second patient showed a much weaker immune response with 1,400/19,800 IgM/IgG antibodies corresponding to a lymphocytotoxic titer increase from 8 to 32. The use of this quantitation technique enables more accurate investigation of antibody bindine to xenoeenic tareet cells than conventional titration techniaues.     

Total hip replacement in patients with hemophilia: 13 hips in 11 patients followed for 1-16 years

During 1973-88, we performed 13 total hip replacements in 11 hemophilia patients, mean age 46 (25-65) years. During the operation, blood loss averaged 920 mL, and a mean of 120, 000 units of factor VIII/IX were used. the mean duration of follow-up was 7 (1-16) years. 5 hips became loose within 6 years, and a further one after 13 years. 4 hips were revised, 2 of them due to infection in patients who were also seropositive for HIV. At the latest follow-up, 10 patients were alive. 6 had no hip pain and 7 could walk at least 1, 000 meters at a time. Although these results are inferior to those obtained in arthrosis, total hip replacement should be considered in hemophiliac patients.     

Factors predicting healing complications in femoral neck fractures: 138 patients followed for 2 years

We have previously studied the radiographic outcome of femoral neck fracture osteosynthesis with either two hook-pins or a four-flanged nail performed by a small group of surgeons with special interest in the methods. In 138 femoral neck fractures a backwards stepwise logistic regression analysis was used to study the significance of preoperative fracture-related factors, intraoperative factors and the osteosynthesis. The development of non-union/re displacement and segmental collapse of the femoral head was influenced by fracture displacement (P 0.001) and method of osteosynthesis (P 0.007). The postoperative scintimetric ratio was influenced by the method of osteosynthesis (P 0.0003), fracture displacement (P 0.004) and by the presence of a posterior fragment (P 0.03).

Reduction of the fracture and positioning of the osteosynthesis were to a large extent within the accepted limits. This may explain why the previously well documented negative effects of malpositioning of the osteosynthesis and inferior reduction were not demonstrated to influence the rate of healing-complications. We conclude that neither patient age, sex nor preoperative fracture variables, with the exception of the extent of fracture displacement, can be used to predict radiographic healing-complications in femoral neck fractures.     

Die Genauigkeit der klinischen Untersuchung bei der Diagnose der rektalen Invagination

Ziel:   

Diese Studie wurde durchgeführt, um die routinemäßige klinische Untersuchung und die Defäkographie in der Diagnose der rektalen Invagination bei obstipierten Patienten zu vergleichen und um die Beziehungen zwischen rektaler Invagination und Symptomen zu untersuchen.     

Calculation and measurements of absorbed dose in total body irradiation

A method which is simple, reliable, and rapid to use in clinical routine for basic dose calculation in total body irradiation (TBI) has been tested with 8 MV x-rays. The dosimetry follows, as far as possible, national and international recommendations for conventional radiotherapy. The dose rate at different locations and depths is calculated from the absorbed dose rate at dose maximum for a phantom size of 30 x 30 x 30 cm in the TBI field (Dc), an inverse square law factor (SAD2/SPD2), the tissue-maximum ratio (TMR), an equivalent phantom and patient size correction factor (A), a factor for lack of back-scattering material (B), an off-axis output correction factor (O), and a factor that corrects for off-axis variations in effective photon beam energy and for oblique beam penetration of the patient (R). The collimator opening is constant for all patient sizes. It is shown that TMR, A, B and R can be measured in conventional geometry in ordinary phantoms but at an extended distance, while Dc, O and SAD2/SPD2 must be measured in TBI geometry. Tests in Humanoid phantoms showed an agreement in measured and planned AP/2 doses of 2% or better. If the calculation method is used for lower photon energies or in other TBI geometries it may be necessary to correct for the elliptical shape of the patient and for back-scattered radiation from the walls or floor.     

Fracture incidence and bone disease in epileptics receiving long-term anticonvulsant drug treatment

Of 155 institutionalized epileptics, 16 (10%) were noted to have suffered from different kinds of fractures when observed over a period of 1 year. The patients with fractures were further investigated with respect to blood and urine chemistry and bone morphology. The serum and urinary calcium values were below the average values for the population. Elevated values for serum alkaline phosphatase and for immunoreactive parathyroid hormone were found in most patients. The values of serum phosphate were distributed close to those of the normal population, while the urinary phosphate values were lower. Examination of bone biopsies revealed a significantly increased amount of osteoid and a significantly increased osteoclastic resorptive activity in epileptics, compared with age-matched controls. Furthermore, a slightly diminished volume of trabecular bone was noted. The high incidence of fractures may be explained by bone disease--a combination of osteoporosis, osteomalacia, and hyperparathyroidism due to chronic treatment with anticonvulsant drugs.     

A drug that facilitates glutamatergic transmission reduces exploratory activity and improves performance in a learning-dependent task

A recently developed benzamide compound which facilitates glutamate receptor-mediated synaptic responses was used to test behavioral consequences of enhanced glutamatergic transmission. The drug was found to depress exploratory activity by rats in a novel environment. At a dose below threshold for causing such effects, drug-treated and control rats exhibited no evident behavioral differences during the acquisition phase of a radial maze experiment. Yet, when tested 2.5 h later, experimental animals were more likely than controls to choose maze arms that had not been entered during the acquisition session, suggesting that the drug enhanced retention of information about prior choices and the maze environment. © 1993 Wiley-Liss, Inc.