Evidence for an increased rate of choline efflux across erythrocyte membranes in Alzheimer's disease

Alzheimer's disease (AD), the major dementing disorder of the elderly, is associated with cholinergic neuronal loss and decreased activity of choline acetyl-transferase (CAT). Previous biophysical studies had suggested an altered conformation of membrane proteins in AD erythrocyte ghosts. Since erythrocytes have a choline transport system and cholinergic neurons are implicated in AD, the present experiments were undertaken to determine if the efflux rate of [¹⁴C]choline was altered in AD erythrocytes. The mean efflux rate constant was highly significantly increased (P<0.01) by greater than 25% in 9 drug-free AD patients compared to 9 sex-matched, drug-free controls of similar age. These results are discussed in terms of potential molecular mechanisms to account for cholinergic neuronal loss in AD.     

A somatic component to myocardial infarction.

Sixty two patients were randomised to be seen by osteopathic physicians for palpation of the thoracic paravertebral soft tissue, T1-T8. Twenty five patients had clinically confirmed acute myocardial infarction. Of the remainder, 22 without known cardiovascular disease served as controls and 15 were placed in an excluded group because of diagnosed cardiovascular disease other than myocardial infarction. Observations were described in predetermined standard terminology. The control group was found to have a low incidence of palpable changes throughout the thoracic dorsum, and these changes were uniformly distributed from T1 to T8. Examination of the group with myocardial infarction disclosed a significantly higher incidence of soft tissue changes (increased firmness, warmth, ropiness, oedematous changes, heavy musculature), confined almost entirely to the upper four thoracic levels. The 15 patients who were excluded from the experimental group because they had various cardiovascular diseases other than myocardial infarction also showed significantly different changes on palpation compared with the group with myocardial infarction. These findings suggest that myocardial infarction is accompanied by characteristic paravertebral soft tissue changes which are readily detected by palpation.     

Proton translocation during denitrification in Rhodopseudomonas sphaeroides f. denitrificans

Proton translocation during the reduction of NO ₃ ^- , NO ₂ ^- , N₂O and O₂, with endogenous substrates, in washed cells of Rhodopseudomonas sphaeroides f. denitrificans was investigated by an oxidant pulse method. On adding NO ₂ ^- to washed cells, anaerobically in the dark, an alkalinization occurred in the reaction mixture followed by acidification. When NO ₃ ^- , N₂O or O₂ was added to cells in the dark or with these compounds and NO ₂ ^- in light an acidification only was observed. Proton translocation was inhibited by carbonyl cyanide-m-chlorophenyl hydrazone.Valinomycin treated cells produced acid in response to the addition of either NO ₃ ^- , NO ₂ ^- , N₂O or O₂. The proton extrusion stoichiometry ( ratios) in illuminated cells were as follows: NO ₃ ^- 0.5N₂, 4.82; NO ₂ ^- 0.5N₂, 5.43; N₂ON₂, 6.20; and O₂H₂O, 6.43. In the dark the comparable values were 3.99, 4.10, 4.17 and 3.95. Thus, illuminated cells produced higher values than those in the dark, indicating a close link between photosynthesis and denitrification in the generation of proton gradients across the bacterial cell membranes.When reduced benzyl viologen was the electron donor in the presence of 1 mM N-ethylmaleimide and 0.5 mM 2-n-heptyl-4-hydroxyquinoline-N-oxide in the dark, the addition of either NO ₃ ^- , NO ₂ ^- or N₂O to washed cells resulted in a rapid alkalinization of the reaction mixture. The stoichiometries for proton consumption, ratios without a permeant ion were NO ₃ ^- NO ₂ ^- ,-1.95; NO ₂ ^- 0.5 N₂O,-3.03 and N₂ON₂,-2.02. The data indicate that these reductions occur on the periplasmic side of the cytoplasmic membrane.Abbreviations BVH reduced benzyl viologen - CCCP carbonyl cyanide m-chlorophenyl hydrazone - DIECA N, N-diethyl-dithiocarbamate - HOQNO 2-n-heptyl-4-hydroxyquinoline-N-oxide - NEM N-ethylmaleimide     

Genome size and complexity in Azotobacter chroococcum

All of eight strains of Azotobacter chroococcum examined contained between two and six plasmids ranging from 7 to more than 200 MDal in size. Strain MCC-1, a derivative of NCIMB 8003, was cured of various of the four largest of its five plasmids and the phenotypes of the strains compared. all fixed nitrogen and exhibited uptake hydrogenase activity. No differences were observed in carbon source utilization or antibiotic, heavy metal or UV resistance. The genome sizes of two strains of A. chroococcum were determined by two-dimensional electrophoresis. Strain CW8, an isolate from local soil containing two small plasmids of 6 and 6.5 MDAl contained unique DNA sequences equivalent to 1.78 x 10(6) (+/- 20%) bp (1.2 x 10(9) Dal). In strain MDC-1, a derivative of MCC-1, containing a 190 MDal and 7 MDal plasmid, the genome size was 1.94 x 10(6) (+/- 20%) bp. In exponential batch cultures, both contained 20 to 25 genome equivalents per cell. MCD-1 exhibited complex UV kill kinetics with a marked plateau of resistance; CW8 showed a simple response inconsistent with the possibility of organization of its DNA into identical chromosome copies capable of independent segregation.     

Carbon monoxide sensitivity of cytochrome oxidase in wheat leaves in relation to dwarfing genes (Rht) in wheat cultivars

Summary Leaves of young seedlings of a number of tall cultivars of wheat, lacking the dwarfing Rht genes, readily responded to a brief 2 min exposure to CO, as assessed by in vivo aerobic assay of nitrate reductase. This test depends on the inhibition of cytochrome c oxidase by CO, which in turn renders cytosolic NADH available for the reduction of nitrate to nitrite in vivo. Semi-dwarf cultivars of wheat (Rht present) did not respond to CO in this way. Since CO forms a complex only with reduced cytochrome a₃, the results indicate differences in the redox state of cytochrome a₃, during in situ respiration of leaves from tall and semi-dwarf plants which are likely to be under genetic control.     

N-terminal amino acid sequence of cytochrome c-552 from Nitrosomonas europaea

Nitrosomonas europaea is an ammonia-oxidizing bacterium which contains multiple c-type cytochromes. Few of these components have been assigned physiological roles, but on the basis of molecular weight and redox potential cytochrome c-552 has been considered to be an analogue of the mitochondrial cytochrome-c family of proteins. We present the N-terminal amino acid sequence (47 residues) of cytochrome c-552 and show that this protein is most closely related to the group of small cytochrome-c components from pseudomonads (cytochromes c-551) and is probably evolutionarily distant from the analagous protein (cytochrome c-550) from the nitrite-oxidizing bacterium Nitrobacter agilis.     

A new species of Rhynchoidomonas Patton, 1910 (Kinetoplastida: Trypanosomatina) from Operophtera brumata (Lepidoptera: Geometridae)

Summary A new species of Rhynchoidomonas Patton was observed in a single adult male winter moth, Operophtera brumata (L.) from England. Intracellular amastigotes, and extracellular epimastigotes and trypomastigotes with an undulating membrane and free flagellum, were present. All stages had a large, reniform kinetoplast. As transmission of the flagellate between generations of winter moths by ingestion of infected faeces is a virtual impossibility, it is suggested that the flagellate's true host may have been a dipteran parasitoid and that an egg, surface-contaminated with the flagellate, was oviposited into or ingested by a winter moth larva. If the parasitoid had died, this flagellate infection could have been carried over to the adult moth. ac]19830601     

CL-proteins and the regulation of lipoprotein lipase activity in locust flight muscle

Lipoprotein lipases in the flight muscles of Locusta migratoria show a marked substrate specificity: diacylglycerols associated with the adipokinetic hormone (AKH)-induced lipoprotein, A+, are hydrolysed at 4 to 5 times the rate of those associated with the lipoprotein in resting (non-hormone-stimulated) locusts, Ayellow. To determine the basis for this discrimination, the effect on the activity of flight muscle lipoprotein lipase of CL-proteins, a major constituent of lipoprotein A+, but not of Ayellow, has been investigated; they inhibit the flight muscle enzyme in a competitive manner whether activity is measured with a natural lipoprotein substrate, a lipid emulsion or a water soluble substrate. Experiments in vivo suggest that the flight muscle enzyme is normally inhibited in resting (non-AKH-stimulated) locusts but, interestingly, injection of synthetic AKH-I relieves the inhibition and increases the activity by 30 to 40%. This is not a direct effect of the hormone on the enzyme, but appears to be related to the hormone-induced formation of lipoprotein A+, so that the majority of CL-proteins in the haemolymph become bound to this lipoprotein and the concentration of free CL-proteins is markedly reduced. We suggest that CL-proteins play a major role in the regulation of lipoprotein lipase in locust flight muscle.     

A unique and essential role for insulin in the phenotypic expression of rat mammary epithelial cells unrelated to its function in cell maintenance

Mammary explants from pregnant rats can be induced in regard to casein synthesis and alpha-lactalbumin activity when cultured in the presence of hydrocortisone, prolactin and levels of insulin approaching physiological concentrations. No detectable induction occurs in the absence of insulin. Although epidermal growth factor and multiplication stimulating activity, in the presence of hydrocortisone, can maintain the initial level of NADH-cytochrome c reductase as well as insulin, neither can substitute effectively for insulin in the induction of the milk proteins. Proinsulin, nerve growth factor, platelet-derived growth factor and fibroblast growth factor are also ineffective substitutes for insulin in this regard. Whereas prolonged tissue exposure to multiplication stimulating activity, hydrocortisone and prolactin does not result in induction of alpha-lactalbumin activity, subsequent addition of insulin leads to prompt response. The results suggest that the ability of insulin to function as a unique, essential factor in the induction of rat milk proteins is independent of its cell-maintenance activity. Thus, in addition to its well established functions in metabolic processes, insulin appears to play a vital role in certain developmental processes.