Differentiating characteristics of deafblindness and autism in people with congenital deafblindness and profound intellectual disability.

BACKGROUND: In persons with deafblindness, it is hard to distinguish autism spectrum disorders from several deafblind specific behaviours caused by the dual sensory impairments, especially when these persons are also intellectually disabled. As a result, there is an over-diagnosis of autism in persons who are deafblind leading to unsuitable interventions. METHODS: Autism as specified by the DSM-IV was studied in 10 persons with congenital deafblindness with profound intellectual disabilities. Behaviours of people with deafblindness and autism (n = 5) and of people with deafblindness without autism (n = 5) were observed in a semi-standardised assessment. RESULTS: All people with deafblindness showed impairments in social interaction, communication and language. In contrast to persons without autism, people with deafblindness and autism showed significantly more impairments in reciprocity of social interaction, quality of initiatives to contact and the use of adequate communicative signals and functions. No differences between the groups were found for quantity and persistence of stereotyped behaviour, quality of play and exploration and adequate problem-solving strategies. CONCLUSIONS: This study indicates that there are some possibilities to differentiate autism from behaviours specific for deafblindness. It also confirms the large overlap in overt behaviours between people with deafblindness and persons with autism.

The influence of a fish oil-enriched diet on the phospholipid fatty acid turnover in the rabbit red cell membrane in vivo.

The influence of the polyunsaturated fatty acid (PUFA) composition of the diet on the rate of fatty acid turnover of individual phospholipids in the erythrocyte membrane in vivo was studied. Following modification of the fatty acid composition of the membrane phospholipids by the use of a fish oil or a linoleic acid enriched diet, phospholipids--labelled in the unsaturated fatty acid at the 2-position of the glycerol moiety--were introduced into the membrane of freshly isolated rabbit erythrocytes. Thereafter, the labelled erythrocytes were reinjected into the bloodstream of the animal. It appears that, with the exception of 1-palmitoyl,2-linoleoyl phosphatidylcholine, all other phosphatidylcholines disappear faster from the erythrocytes of fish oil-fed rabbits than from the red cells of linoleic acid-fed rabbits. Another parameter, which possibly influences the turnover rates of PUFA containing phospholipids, can be peroxidation. An attempt was made to measure peroxidative damage of lipids in vivo by the introduction of 1-palmitoyl,2-cis-parinaroyl phosphatidylcholine (PnPC)--a probe to measure oxidative stress--into the membrane of freshly isolated erythrocytes, in the same way as is described for the radioactive phospholipids. The data demonstrate that the fluorescent signal from the PnPC decreases at a fast rate which is independent of the dietary conditions.

Comparison of the effects of dietary vitamin E on in vivo and in vitro parameters of lipid peroxidation in the rabbit.

This study has investigated the effect of dietary vitamin E on markers of antioxidant status. Four groups of rabbits received diets containing 30 energy percent (en%) total fat (7.8 en% contributed by linoleic acid) for 12 weeks. D,1-alpha tocopheryl acetate was added to the diets to obtain a range of vitamin E concentrations (49, 114, 179, or 775 tocopherol equivalents per kg diet). Increased vitamin E concentrations were demonstrated in plasma lipoproteins and erythrocyte membranes following supplementation, and dietary effects on lipid peroxidation were investigated by (i) monitoring a fluorescent parinaric acid probe incorporated into erythrocyte membranes in vivo, (ii) determination of malondialdehyde and oxysterols in plasma, and (iii) investigation of the susceptibility of low density lipoprotein (LDL) to copper-induced conjugated diene formation in vitro. No effects of vitamin E were observed on parinaric acid oxidation in vivo or on the accumulation of lipid peroxidation products in plasma, but the resistance of LDL to oxidation in vitro increased significantly as vitamin E was supplemented to the diets. Our results demonstrate that under these dietary conditions (7.8 en% linoleic acid) increasing the vitamin E content of plasma and erythrocytes approximately two-fold does not reduce the level of lipid peroxidation in vivo, indicating sufficient antioxidant capacity on the lowest vitamin E diet. In contrast, LDL became more resistant to an extreme oxidative stress applied in vitro. The relevance of these assays to currently proposed mechanisms of atherosclerosis is discussed.

In vivo turnover of 1,2-dipalmitoylphosphatidylcholine and sphingomyelin in rabbit erythrocytes.

The in vivo turnover of both 1,2-dipalmitoylphosphatidylcholine (DPPC) and sphingomyelin (SM) in rabbit erythrocytes was studied. DPPC, either 14C-labelled in the fatty acyl chain at the 2-position of the glycerol moiety or 3H-labelled in the choline's methyl group, and [N-methyl-14C]SM (bovine) were introduced into the membrane of freshly isolated rabbit erythrocytes by using phospholipid transfer proteins. Thereafter, the labelled erythrocytes were reinjected into the bloodstream of the animal. Analysis of blood samples shows that both labels disappear from the circulating cells with the same rate, resulting in a half-time value of about 6.4-6.6 days. This result demonstrates that the loss of DPPC from the cells is due to transfer of intact molecules to the plasma and that a deacylation process is of no or minor importance as mechanism of renewal of DPPC. Labelled sphingomyelin, introduced into the rabbit erythrocyte membrane in a similar way, disappears from the circulating red cell with a half-time value of 15.5 days. This accounts for a daily replacement of the total SM pool by 3.2%.

In vivo turnover of phospholipids in rabbit erythrocytes.

The rate of phospholipid turnover in erythrocyte membranes in vivo has been studied using a recently developed procedure (Kuypers, F.A., Easton, E.W., van den Hoven, R., Wensing, T., Roelofsen, B., Op den Kamp, J.A.F. and van Deenen, L.L.M. (1985) Biochim. Biophys. Acta 819, 170-178). The technique is based on the application of phospholipid transfer proteins in order to introduce trace amounts of radiolabelled phospholipids in the membrane of isolated erythrocytes, followed by re-injection of the erythrocytes into the bloodstream of the animal. The most abundant species of the phosphatidylcholine (PC) class, 1-palmitoyl,2-linoleoyl PC, has, on the basis of loss of the radioactivity in its fatty acyl part, a relatively high turnover with a half-time value of 1.5 days. Other PC species studied exhibit more moderate turnover rates of about 5 days for 1-palmitoyl,2-oleoyl PC and 1-stearoyl,2-arachidonoyl PC. Dipalmitoyl PC, labelled in the polar headgroup, turns over at a slow rate with a half-time value of 9 days. From these data and the relative abundance of the various species, it can be calculated that, on a daily basis in vivo, about one third of the total PC pool in rabbit erythrocyte membranes is replaced and/or modified by de-/reacylation. The only phosphatidylethanolamine (PE) species studied so far, 1-palmitoyl,2-arachidonoyl PE, appeared to be renewed at a relatively low rate with a half-time value of 12 days. The data demonstrate that the in vivo turnover values of phospholipids in the erythrocyte membrane may depend on their polar head group structure, their localization in the membrane and, to a large extent, on their fatty acid composition.