Antibodies to Cholinergic Neurons in Alzheimer''s Disease

Alzheimer's disease (AD) is associated with degenerative changes in nuclei of the basal forebrain which provide most of the cholinergic input to the cortex and hippocampus and with a reduction in presynaptic cholinergic parameters in these areas. Although the etiology and pathogenesis of AD are not known, several reports indicate the involvement of immunological mechanisms. In the present work we examined the existence of antibodies in sera of AD patients that bind specifically to cholinergic neurons. As antigens we employed the purely cholinergic electromotor neurons of the electric fish Torpedo which are chemically homogeneous and cross-react antigenically with human and other mammalian cholinergic neurons. Our findings show that immunoglobulins from sera of AD patients bind to a specific antigen (molecular mass 200 kilodaltons) in the cell bodies and axons of Torpedo electromotor neurons and that the levels of such antibodies are significantly higher in AD patients than in controls. The possible role of these antibodies in the cholinergic dysfunction in AD and their diagnostic potential are discussed.     

Mutation to rifampicin resistance at the beginning of the RNA polymerase beta subunit gene in Escherichia coli

Summary The unusual recombinant plasmid pRC19 carrying the N-terminal fragment of the Escherichia coli RNA polymerase rpoB gene was found to specify high level rifampicin resistance of E. coli cells. Sequence analysis of this plasmid revealed one substitution only: transversion GT, leading to amino acid substitution Val¹⁴⁶Phe. This mutational change marks the second domain of the subunit involved in rifampicin binding.     

Overproduction of protein p53 contributes to simian virus 40-mediated transformation.

The possible involvement of p53 overproduction in simian virus 40 (SV40)mediated transformation was studied by using the rat embryo fibroblast focus formation assay. Transformation by wild-type SV40 was enhanced two- to threefold by cotransfection of a plasmid overexpressing mouse p53. More significantly, such a plasmid could partially complement a transformation-defective deletion mutant of SV40. Hence, the ability of SV40 T antigen to induce high p53 levels may indeed be directly relevant to the viral transforming potential.     

Potentials of spinal motoneurons in cats with experimental tetanus

Potentials of motoneurons of the lower segments of the spinal cord were recorded with the aid of intracellular microelectrodes in experiments on cats with induced tetanus produced by injection of tetanus toxin (1500–2000 mouse LD₅₀) into the extensor muscles of the left shin. Neither afferent volleys of impulses in cutaneous and muscle nerves, nor antidromic volleys in the corresponding ventral roots, produced IPSPs in motoneurons of the extremity into which toxin was injected. The form both of antidromic peak potentials and of monosynaptic EPSPs in motoneurons in which IPSPs were blocked by tetanus toxin did not differ from the form of corresponding potentials of motoneurons in normal cats. The values of threshold depolarization for peak discharges during synaptic and direct stimulation were equal in tetanus and control motoneurons. Resistance and time constant values of the membrane in "tetanus" motoneurons did not differ from the corresponding values for "control" motoneurons.N. I. Pirogov Second Medical Institute, Moscow. Translated from Neirofiziologiya, Vol. 1, No. 1, pp. 25–34, July–August, 1969.     

Substitution of 2-Aminoadenine and 5-Methylcytosine for Adenine and Cytosine in Hybridization Probes Increases the Sensitivity of DNA Fingerprinting

An oligonucleotide (m⁵C-am²A-m⁵C)₅ containing 2′-amino-deoxyadenosine (am²A) and 5-methyldeoxycytidine (m⁵C) residues has been synthesized and compared with unsubstituted pentadecadeoxyribonucleotide (CAC)₅ as a hybridization probe for DNA fingerprinting. It was shown that considerably higher sensitivity can be achieved with the modified analog.     

Modifying effect of deep hypoxia on neutron-irradiated mice

Deep hypoxia was shown to influence the survival of animals, the state of the small intestine mucosa and the haemopoietic system. DMF (LD50/30) was 2.49 and 1.66 with X- and neutron radiation, respectively. As to haemopoietic stem cells X-irradiated in vivo, D0 was 0.96 +/- 0.04 Gy (control) and 2.82 +/- 0.14 Gy (anoxia). With neutron irradiation, D0 was 0.44 +/- 0.01 Gy and 0.8 +/- 0.03 for the control and experimental animals respectively.