Sugar-Binding Activity of Pea Lectin Expressed in White Clover Hairy Roots.

Introduction of the pea (Pisum sativum L.) lectin (PSL) gene into white clover (Trifolium repens L.) hairy roots facilitates nodulation by the nitrogen-fixing bacterium Rhizobium leguminosarum biovar viciae, which normally nodulates pea and not white clover (C.L. Diaz, L.S. Melchers, P.J.J. Hooykaas, B.J.J. Lugtenberg, and J.W. Kijne [1989] Nature 338: 579-581). Here, we show that PSL is functionally expressed in transgenic white clover hairy roots transformed with the PSL gene. PSL could be isolated from these roots by affinity chromatography. Immunoanalysis of PSL showed the presence of polypeptides corresponding to the PSL precursor and its [beta] subunits. In addition, we developed a highly sensitive localization technique based on specific binding of a glycan moiety of rat IgE to PSL. Similar to the situation in pea roots, PSL appeared to be localized on the external cell surface of elongated epidermal cells and on the tips of emerging and growing root hairs of transgenic white clover hairy roots. PSL was not observed on normal white clover roots and on hairy roots without the PSL gene. These results show that (a) in transgenic white clover hairy roots, PSL is correctly processed and targeted to root cells susceptible to rhizobial infection, and (b) like in pea roots, PSL is surface bound with at least one of its two sugar-binding sites available for (rhizobial) ligands.

Implications of lung corrections for dose specification in radiotherapy.

The influence of taking into account the lung density in the calculation of the dose distributions was examined for a group of 23 patients with bronchus carcinoma. Anatomical information and electron densities were available by means of CT scans. All calculations were made for cobalt-60 gamma rays using a patient specific multiple field irradiation technique. The effect of lung tissues for the dose distributions was calculated using a generalization of Batho's method. All patients entered into this study were planned to receive a minimum tumor dose of 60 Gy, calculated without correction for lung density. The actual dose in each patient was recalculated with lung correction. In the group of patients the corrected minimum tumor dose varied between 63 Gy and 77 Gy (105-128%). The calculated homogeneity of the dose in the target area and the dose to surrounding normal tissues are also affected by lung correction. For different radiation techniques and different methods of dose specification, the interrelation between corrected and uncorrected dose is presented in tables. The impact of lung correction on the uncorrected dose schedules that are commonly used in the treatment of patients with lung cancer is discussed.

Computerized tomography in carcinoma of the prostate: treatment volume and morbidity in radiotherapy.

Fifty-five patients with adenocarcinoma of the prostate were treated with external beam irradiation. In 31 of them conventional localization was used and in 24 computerized tomography was used in the localization of the treatment volume. In these 24 patients we see a larger treatment volume with a wider distribution. This method would appear to be superior to the use of standard irradiation fields. The larger treatment volume did not increase morbidity.

Curative radiotherapy in Hodgkin's disease: significance of haematogenous dissemination established by examination of peripheral blood and spleen.

Studies of peripheral blood leucocyte concentrates in patients with Hodgkin's disease showed two types of cells believed to be typical for the disease in a number of patients. Involvement of the spleen as diagnosed after splenectomy and histological examination showed a close correlation with the presence of these characteristic cells in the peripheral blood. This is believed to be an argument for haematogenous spread or a multicentric origin of the disease in these cases. The results of attempted curative high-voltage radiotherapy with total node irradiation in 24 patients seem to support this concept. On the basis of the Rye classification of clinical stages the results of radiotherapy are not predictable. Six patients in stage II and seven in stage III were in remission, one in each of stages II and IV, and six in stage III had recurrences of the disease within one year. A division into localized or disseminated forms of the disease based on the investigations of blood and spleen showed all localized cases in remission; of the disseminated cases one reached a remission and all others had recurrences. In three patients the therapy could not be completed. These preliminary treatment results are believed to support the idea of a special role of the spleen in the dissemination of the disease. A new classification of clinical stages in Hodgkin's disease is proposed.