Isolation of a conserved sequence deleted in Duchenne muscular dystrophy patients.

We have isolated a DNA sequence (HIP25) by subtraction- hybridisation which is deleted in a number of Duchenne muscular dystrophy (DMD) patients. HIP25 is conserved in evolution and hybridises to human fetal and adult muscle mRNA. HIP25 is absent in human fetal fibroblast mRNA. Physical mapping data localise this sequence within Xp21 between the breakpoints of X;autosome translocations found in two females suffering from the disease. HIP25 is a candidate exon sequence for the basic defect in DMD boys deleted at this locus.     

Human DNA (cytosine-5)methyltransferase selectively methylates duplex DNA containing mispairs.

The presence of the C.C mispair in a defined duplex oligodeoxynucleotide enhanced its capacity to serve as a substrate for highly purified human DNA methyltransferase. Analysis of tritiated reaction products showed that the C.C mispair acted as a "methylation acceptor" in that it was itself rapidly methylated. The m5C.G base pair also enhanced the capacity of the oligodeoxynucleotide to serve as a substrate for the enzyme. However, this complementary base pair was found to act as a "methylation director". That is, the presence of the m5C in one strand induced the enzyme to rapidly methylate at the cytosine residue on the opposite strand in an adjacent C.G base pair.     

An electrophoretic karyotype for Schizosaccharomyces pombe by pulsed field gel electrophoresis.

The three chromosomal DNAs of S. pombe have been fractionated by pulsed field gel electrophoresis. The resulting molecular karyotype will greatly speed gene mapping in this organism, and it indicates that the separation range of the technique extends to DNA molecules as large as 9,000,000 base pairs.     

Construction and characterisation of a hybrid-hybrid monoclonal antibody recognising both carcinoembryonic antigen (CEA) and vinca alkaloids

Summary Recent developments of hybridoma technology have allowed us to prepare a bispecific monoclonal antibody recognising both the tumour-associated antigen carcinoembryonic antigen (CEA) and the cytostatic vinca alkaloids. The yields of the hybrid-hybrid 28.19.8 monclonal after affinity chromatography purification are close to 50% of the total Ig produced.The hybrid-hybrid has a molecular weight ca. 150000 daltons. The heavy chains of the hybrid-hybrid are a 1 heavy chain from the parental anti-CEA monoclonal and a 2a heavy chain from the anti-vinca alkaloid donor lymphocytes.     

Antibody to myelin constituents: A possible factor in induction of cell-mediated demyelination

Results from this laboratory have demonstrated that¹⁴C-labeled myelin opsonized with antibodies raised to purified CNS myelin in rabbit is phagocytized by cultured macrophages in larger amounts than untreated myelin or myelin opsonized with preimmune serum. The cultured macrophages produced high amounts of radioactive cholesterol ester and triglyceride from the antibody-treated myelin while much less was formed from preimmune serum-treated or untreated myelin. Antiserum to galactocerebroside also greatly enhanced the formation of radioactive cholesterol ester, while that to myelin basic protein as well as to other myelin constituents had little or no effect. Serum from Lewis rats with acute EAE 13–14 days after immunization with whole CNS myelin also stimulated radioactive cholesterol ester formation compared to serum from Freund's adjuvant-injected controls (FAC). Serum from EAE rats as a result of myelin basic protein injection was as active as that from rats with whole myelin injection. No galactocerebroside antibody could be demonstrated in the EAE sera, although a strong immunostaining to myelin basic protein and proteolipid protein was demonstrated. IgG prepared from EAE serum also showed stimulatory effects compared to IgG from FAC serum, but much of the activity was lost, and the possibility that other factors may be involved is discussed. These experiments provide evidence that myelin phagocytosis and digestion by macrophages is enhanced by the presence of antibody to myelin. In EAE this antibody may leak into CNS with the breakdown of the blood-brain barrier. A humoral involvement in demyelination in EAE is implicated, and these findings may be extended eventually to the demyelinative mechanism in multiple sclerosis where IgG is found in large amounts in the CNS.Special Issue Dedicated to Dr. Abel Lajtha.     

Aluminium bone disease in patients receiving plasma exchange with contaminated albumin.

Aluminium balance studies were carried out on eight patients with various immunological disorders who were receiving plasma exchange with albumin solutions known to be contaminated with aluminium. Four patients with impaired renal function (creatinine clearance less than 50 ml/min) retained between 60% and 74% of the aluminium infused during a single plasma exchange. Transiliac bone biopsy specimens from three patients in this group had a high content of aluminium and showed histological evidence of current or previous bone disease related to aluminium. Two of these patients suffered intermittent bone pain. The main route of excretion of injected aluminium was in urine, only a small proportion of the total input being removed in the "plasma bag" during plasma exchange. The extent of aluminium retention and bone deposition was not reflected by the plasma aluminium concentration before or after plasma exchange. Treatment of five patients with intravenous desferrioxamine increased the plasma aluminium concentration and urinary output of aluminium in those with evidence of aluminium retention. These studies show that patients with poor renal function receiving treatment with albumin contaminated with aluminium retain the metal and deposit it in bone, where it may eventually cause aluminium bone disease. Plasma exchange should be used with caution in patients with renal impairment.