Sch 42029, a naturally produced dopamine receptor ligand: Taxonomy,fermentation, isolation and structure

Summary A natural product, Sch 42029, isolated from the fermentation of anActinoplanes sp. (SCC 1971) was found to displace Sch 23390 from the dopamine-1 (D₁) receptor. The compound was isolated from the fermentation broth by adsorption of the filtrate on XAD-16 resin, elution with water-methanol, followed by purification by gel-permeation chromatography and HPLC. Using spectroscopic analysis, the structure was determined to be 2,5-dihydroxy acetanilide. The pure compound displaced Sch 23390, a D₁-selective ligand, at aK _i of 1.6 m and spiperone, a D₂-selective ligand, at aK _i of 200 m.     

Locomotor disability in very elderly people: value of a programme for screening and provision of aids for daily living.

OBJECTIVE--To assess the prevalence of potentially reversible locomotor disabilities in elderly subjects and the cost effectiveness of providing aids for daily living. DESIGN--Population based randomised controlled trial of subjects aged greater than or equal to 85 living independently in an inner London borough. SETTING--21 Electoral wards of the London Borough of Hackney. SUBJECTS--1255 Subjects aged greater than or equal to 85 living in their own home whose names were obtained from general practitioner lists and cross checked against the electoral register, 511 of whom were subsequently found to be ineligible. Of the 744 remaining, those with disability on screening were randomised and allocated to an intervention group (36) or a control group (43), in which intervention was postponed until four weeks, after the follow up assessment. Subjects with aids supplied previously were excluded from the intervention phase. INTERVENTIONS--Provision of raised toilet seat, teapot tipper, tap turner, shoe horn and elastic laces, and double handled saucepan. MAIN OUTCOME MEASURES--Degree of difficulty (grades 1-4) with specific tasks (getting on and off a toilet, pouring from a teapot into a cup, turning taps on and off, carrying a saucepan of standard weight, and putting on shoes) and time taken to perform them. RESULTS--545 (73%) Of the 744 eligible subjects assessed; 428 had no disability and 118 had difficulty with at least one task. Some had had their disability recognised before the study and already had aids, representing half of those with difficulty getting on and off the toilet but 24% for putting on shoes and 13% for pouring from a teapot and turning on a tap. The mean number of difficulties was similar between the groups (intervention group 1.7, control group 1.6). Time taken to complete the tasks corresponded with the observed grade of difficulty. All aids were associated with reduced difficulty according to observer assessment (% improvement intervention group v control group: raised toilet seat, 71 v 13 teapot tipper 100 v 33; tap turner 100 v 0; saucepan 88 v 0; shoe horn 50 v 13) and time taken to complete the tasks. A cost benefit analysis of this screening-intervention programme suggested a total cost of 32 pounds per individual benefit. CONCLUSIONS--Appreciable degrees of unrecognised locomotor disability are detected on screening of very elderly people living independently. Providing aids offers a feasible and cost effective means of improving function in such people.     

Predicting resource utilization: the utility of optimal foraging models

Predicting how predation changes communities is an important challenge for ecologists. One view assumes that predictions can be made in terms of behavioural phenomena. Static optimality methods have been used to devise models of prey choice and are thought to have performed well. Two examples from the literature show that models of diet choice have either been applied without first testing them at the individual level, or have been tested in a way that does not fulfil all their assumptions. A discussion of the nature of mathematical models shows why it is dangerous to translate theories into natural language and how important it is to appreciate the limitations on the mathematical functions describing behaviour. A final section discusses behavioural phenomena such as satiation and learning, which are likely to limit the predictive capacities of static optimization models. It is likely that dynamic models are the way forward although they may be harder to apply at the ecological level.     

Age-related changes in the haematology of female F344 rats

As little comprehensive baseline data are available on age-related haematological changes in genetically-defined rat strains, the haematology of female F344 rats is described in animals sampled at 2, 4, 8, 20, 66 and 121 weeks of age. Values for Hb, RBC and PCV increased from 2 weeks of age to reach adult levels at 8 weeks, whereas MCV, MCH and reticulocyte counts were high initially but decreased to reach the adult range at 8 weeks. Between 66 and 121 weeks, reticulocyte counts were significantly increased and values for MCHC significantly decreased. Lymphocytes were the predominant white cell type in each age group. The absolute numbers of neutrophils and lymphocytes showed slight variations between 2 and 66 weeks and both cell types increased significantly between 66 and 121 weeks. Platelet counts showed no overall age-related trends. Fibrinogen values increased from 2 weeks of age to reach the adult level at 8 weeks. One animal of the 14 sampled at 121 weeks showed changes in the blood, liver and spleen consistent with a diagnosis of lymphoid leukaemia.     

Murine elongation factor 1 alpha (EF-1 alpha) is posttranslationally modified by novel amide-linked ethanolamine-phosphoglycerol moieties. Addition of ethanolamine-phosphoglycerol to specific glutamic acid residues on EF-1 alpha

Elongation Factor 1 alpha (EF-1 alpha), an important eukaryotic translation factor, transports charged aminoacyl-tRNA from the cytosol to the ribosomes during poly-peptide synthesis. Metabolic radiolabeling with [3H] ethanolamine shows that, in all cells examined, EF-1 alpha is the major radiolabeled protein. Radiolabeled EF-1 alpha has an apparent Mr = 53,000 and a basic isoelectric point. It is cytosolic and does not contain N-linked oligosaccharides. Trypsin digestion of murine EF-1 alpha generated two major [3H]ethanolamine-labeled peptides. Three peptides were sequenced and were identical to two distinct regions of the human EF-1 alpha protein. Blank sequencing cycles coinciding with glutamic acid in the human cDNA-derived sequence were also found to release [3H]ethanolamine, and compositional analysis of these peptides confirmed the presence of glutamic acid. Dansylation analysis demonstrates that the amine group of the ethanolamine is blocked. These results indicate that EF-1 alpha is posttranslationally modified by the covalent attachment of ethanolamine via an amide bond to at least two specific glutamic acid residues (Glu-301 and Glu-374). The hydroxyl group of the attached ethanolamine was shown by mass spectrometry and compositional analysis, to be further modified by the addition of a phosphoglycerol unit. This novel posttranslational modification may represent an important alteration of EF-1 alpha, comparable to the regulatory effects of posttranslational methylation of EF-1 alpha lysine residues.     

A novel pathway for glycan assembly: biosynthesis of the glycosyl-phosphatidylinositol anchor of the trypanosome variant surface glycoprotein

The trypanosome variant surface glycoprotein (VSG), like many other eukaryotic cell surface proteins, is anchored to the plasma membrane by a glycosyl-phosphatidylinositol (GPI) moiety. This glycolipid is assembled first as a precursor (glycolipid A) that is then covalently attached to the newly synthesized polypeptide. We have developed a trypanosome cell-free system capable of performing all of the steps in the biosynthesis of the glycan portion of glycolipid A. Using [3H]sugar nucleotides as substrates, several biosynthetic intermediates have been identified. From structural analyses of these intermediates, we propose a pathway for GPI biosynthesis. Based on comparisons between the VSG GPI anchor and similar structures in other cells, we believe that this same pathway will apply to the GPI anchors, and the related insulin-mediator compound, of higher eukaryotes.     

Cell cycle-related transfer of proteins between the nucleus and cytoplasm of Physarum polycephalum

The proteins of wild-type and polyploid plasmodia of P. polycephalum were prelabelled with [³H]leucine and [¹⁴C]leucine. The two types of plasmodia were then fused for 2 h. Following fusion the nuclei were isolated and the smaller wild-type cell nuclei separated from the larger polyploid cell nuclei. The proteins were isolated from the recipient cell nuclei and the recipient nuclear proteins extracted. Ratios of ³H/¹⁴C in the various nuclear protein fractions show that during fusion differential transfer of labelled preformed proteins from the donor cell into the recipient cell nucleus occurs. The quantity of proteins transferred varies among the different fractions and with the phase of the cell cycle. Isotopic dilution experiments indicate that these differences in protein transfer are, in part, due to a high rate of synthesis and turnover of the nuclear proteins.     

Morphological transformation of cells induced by Kirsten sarcoma virus transforming factor is independent of serine protease

Reports from several laboratories have suggested that the virus transformed state may be maintained either by ectopically produced growth factors of alternatively by ectopically produced serine proteases including plasminogen activator. Here we show that the maintenance of transformation induced by Kirsten sarcoma virus induced growth factor(s) is independent of serine proteases in that (1) the factors are not themselves serine proteases, and (2) the growth factors do not induce the expression of detectable serine proteases or plasminogen activator.