Characterisation of Putative Monoclonal Anti-G3M(U) and Anti-G3M(G) Reagents and their Antigenic Determinants

Monoclonal antibodies (MAbs) against IgG3 allotypic markers were evaluated in haemagglutination inhibition and IgG3 capture ELISA. MAbs PNF69C and 200D1 exhibited G3m(u) and G3m(g) specificity respectively. In HAI target epitopes detected by MAbs were remarkably stable to physiochemical degradation. Western blotting revealed that MAb 200D1, bound to intact IgG3 heavy chain disease protein and not its pFc' fragment; a result consistent with the CH2 domain location of the G3m(g) allotope. The G3m(u) allotope is also located within this domain. Suprisingly anti-G3m(u) MAb PNF69C bound to the pFc' of IgG3-related protein, HW, and to the pFc' of IgG1-related protein, PR, in Western blot.     

The cost benefit of vaccinating broiler flocks against subclinical infectious bursal disease

In an attempt to reduce economic losses due to subclinical infectious bursal disease (IBD), broilers reared in 23 houses known to have been infected with IBD virus were vaccinated with live, attenuated IBD virus vaccine at 20 days of age. Vaccination of either one, two or three consecutive flocks resulted in significant increases in net income and average bird weight, and in a decrease in mortality. An improvement in broiler performance was not restricted to vaccinated flocks, but was also apparent for at least 1 year following placing of the first vaccinated flock in subsequent flocks reared in the same houses.     

Development of a high performance zinc-62/copper-62 radionuclide generator for positron emission tomography

Clinical utilisation of positron emission tomography could be enhanced by the availability of shortlived radionuclides derived from generator systems. The zinc-62/copper-62 combination is one such system which could be used as a source for a number of copper-62 radiopharmaceuticals. We have developed and optimised a high activity (5.6 GBq, 150 mCi) zinc-62/copper-62 generator to provide ⁶²CU in a form that is suitable for direct labelling of pyruvaldehyde-bis-(N ⁴-methylthiosemicarbazone)-copper(II), Cu(PTSM). The distribution coefficients of Zn(II) and Cu(II) between anion-exchange resin and various hydrochloric acid/organic solvent mixtures were measured. Based on these measurements a generator eluent of 0.3 M HCl/40% ethanol provided ⁶²CU in >90% yield in a 3-ml volume. A very low ⁶²Zn breakthrough of less than 3×10^–7% was achieved. Copper-PTSM was successfully labelled with the no-carrier-added ⁶²Cu eluent directly from the generator with 94% radiochemical yield. Offprint requests to: J. Zweit, The Royal Marsden Hospital     

Von Willebrand factor has more than one binding site for platelets

By the use of a series of monoclonal antibodies against platelet membrane glycoproteins (GP) and the von Willebrand factor (vWF), it is shown that thrombin-induced binding to GP IIb/IIIa involves a different site on vWF from ristocetin-induced binding to GP Ib.     

Enhancement by testosterone of dimethylnitrosamine carcinogenesis in lung, liver and kidney of inbred NZR/Gd female rats

The effect of androgenic treatments on single dose dimethyl-nitrosamine(DMN) carcinogenesis was studied in 60 female NZR/Gd inbredrats, 25 of which were intact and received DMN 20 mg/kg i.p.in one dose after 48 h starvation, while 35 received DMN combinedwith testosterone injections every 4 weeks beginning 15 daysbefore or after DMN, and in 29 rats combined also with ovariectomy.Sixteen female rats underwent ovariectomy and received testosteroneevery 4 weeks with no DMN. There were also 107 untreated intactcontemporaneous control female rats. A single dose of DMN inducedalveologenic lung (16%), hepatocellular (24%) and kidney epithelial(44%) tumours in intact rats, and the incidences of lethal tumoursat these sites were significantly enhanced by androgenic treatmentsfollowing the carcinogen, most markedly in the kidney. Androgenictreatment given before DMN injection had no significant effecton kidney or liver tumour incidences, but the carcinogenic responsein lung was still strongly enhanced.     

Genetic and sex-linked factors influencing hbs antigen clearance 1. nonimmune clearance in inbred strains of mice

Differences in the clearance values of polyvinylpyrrolidonc (K_PVP) and HBs antigen (K_HBs) were seen in several strains of inbred mice. In addition, in all strains studied K_HBs was greater in females than in males, while K_PVP was not significantly different in the two sexes. In the strain with the lowest K_HBs values, the incidence of HBs antibody formation was lower than in the other strains. These data indicate that genetic and sex-linked factors influence nonimmune clearance of HBs antigen in mice. If similar factors exist in man they may explain some of the variation in clinical manifestation of HBV infection.     

Detection of Ca antigen in sera from normal individuals and patients with benign and malignant breast disease

Two assay procedures, an inhibition radioimmunoassay (Inhibition-RIA) and an immunoradiometric assay (IRMA), were established for the detection of circulating tumour-associated Ca antigen. There was a good correlation between results (r = 0.987) but the Inhibition-RIA was selected for extended tests on human sera from patients with breast disease because of its greater ease and economy in use. Circulating Ca antigen was not exclusive to malignancy and the level failed to discriminate between patients with primary carcinoma and those with benign disease. Ca antigen was present in sera of 100 healthy individuals (median 7.1 micrograms ml-1, range 1.8-24.4 micrograms ml)-1, 39 patients with benign disease (median 9.9 micrograms ml-1, range 2.5- greater than 100 micrograms ml-1) and in 67 patients with primary carcinoma (median 11.0 micrograms ml-1, range 3.8- greater than 100 micrograms ml-1). Elevated Ca antigen levels were found in 50% of patients with metastatic spread (median 30.7 micrograms ml-1, range 8.2- greater than 100 micrograms ml-1) and in some patients with primary disease but further studies are needed to determine the prognostic significance. Immunochemical studies confirmed that Ca antigen is a normal serum product but its function is unclear.