Age-related changes in human platelet function in vitro

Platelet aggregation and ATP release were simultaneously measured in platelet-rich plasma samples obtained from humans of various age. In subjects aged over 59 years, an increase was found in platelet sensitivity to ADP and collagen as well as elevated aggregation amplitudes 5 min after induction with low concentrations of the aggregation agents. At 1 mumol/l ADP, old persons had a higher incidence of a secondary aggregation wave. Platelets from old subjects also released more ATP in response to collagen stimulation. Since no age-related changes are commonly found in the platelet count, the observed increase in platelet sensitivity to aggregation agents cannot be regarded as a mere compensatory reaction. An attempt is made to relate altered platelet function to peculiarities of lipid metabolism associated with ageing.     

Stimulation of the N-methyl-D-aspartate receptor has a trophic effect on differentiating cerebellar granule cells

N-methyl-D-aspartate (NMDA) supplementation of cerebellar cultures enriched in granule neurones (about 90%) prevented the extensive cell loss which occurs when cultivation takes place, in serum containing media, in the presence of 'low' K+ (5-15 mM). Estimation of tetanus toxin receptors and N-CAM contents indicated that NMDA rescued primarily nerve cells. The influence of NMDA in promoting cell survival was blocked by the receptor antagonist, 2-amino-5-phosphonovalerate. The effect depended both on the concentration of NMDA and on the degree of depolarization of cells, the affinity in the presence of 15 mM K+ being similar to that of NMDA receptor binding. The results attest a new role for excitatory amino acid transmitters by showing that they can exert a stage-dependent trophic action on developing nerve cells.     

Acute effect of endogenous inhibitors and exogenous cytostatics on the ultrastructure of bone marrow cells. I. Single dose of 1,2 : 5,6-dianhydrogalactitol (DAD).

The ultrastructural effects of the endogenous inhibitor, granuloid crude extract (GCE), known to control the proliferation of myeloid cells, and of the current hexitol derivative, 1,2 : 5,6-dianhydrogalactitol (DAD) were compared on the rat bone marrow. A single intraperitoneally injected LD50 dose of DAD induces the following changes in the fine structure: The mitochondria become swollen, the matrix less electron-dense, the cristae fragmentate, the ribosomes aggregate, anomalies appear in the perinuclear the cell membranes, and myelin figures and intranuclear bodies develop. Autophagy, degeneration and the phagocytotic activity of the reticulum cells is appreciable in 4 hours after treatment and increase by the 24th hour. The toxic effect of DAD is cell aspecific but in the ultrastructure its myelotropic effect manifests earlier than in erythropoiesis. In contrast, the arrest caused by a single dose of the endogenous granuloid inhibitor [2] is cell-specific and non-toxic.     

Contaminated antiseptics--an unnecessary hospital hazard

A total of 284 antiseptic solutions were studied to check for their sterility. The overall antiseptic contamination rate was 15.14%. 14.85% of freshly prepared antiseptics were contaminated. Here, the problem could be attributed to inadequate precautions while preparing the antiseptics. 15.3% of the in-use antiseptics were contaminated. This could be due to improper handling. Non-fermenters (45.45%), Pseudomonas aeruginosa (30.30%) and Klebsiella spp. (22.72%) were the commonest organisms recovered from the antiseptics. In 44.44% of patients, the isolates obtained from the catheterised urine in the same wards matched with the isolates from antiseptics of that ward. Antiseptic solutions have to be regularly monitored. If they are found to be contaminated, they should be discarded immediately and replaced by fresh sterile antiseptics otherwise instead of preventing infection, antiseptics will become a source of hospital-acquired infection.     

The influence of some antidepressant drugs on the nuclear volume of rat cingular cortex cells in culture

The changes in the volume of cell nuclei of the rat cingular cortex were investigated in culture after incubation with some antidepressant drugs. Two-week incubation of the cingular cortex culture with both tricyclic (desipramine, imipramine, amitryptyline) and non-tricyclic (mianserin) antidepressants in concentration of 3 X 10(-6) M resulted in a decrease of the volume of the cell nuclei. Because the size of the nucleus is regarded as a criterion of the cell metabolic activity, our results may point to a diminished activity of metabolic processes of the cells.     

Optimal number of pinholes in multi-pinhole SPECT for mouse brain imaging--a simulation study

This study simulates a multi-pinhole single-photon emission computed tomography (SPECT) system using the Monte Carlo method, and investigates different multi-pinhole designs for quantitative mouse brain imaging. Prior approaches investigating multi-pinhole SPECT were not often optimal, as the number and geometrical arrangement of pinholes were usually chosen empirically. The present study seeks to optimize the number of pinholes for a given pinhole arrangement, and also for the specific application of quantitative neuroreceptor binding in the mouse brain. An analytical Monte Carlo simulation based method was used to generate the projection data for various count levels. A three-dimensional ordered-subsets expectation-maximization algorithm was developed and used to reconstruct the images, incorporating a realistic pinhole model for resolution recovery and noise reduction. Although artefacts arising from overlapping projections could be a major problem in multi-pinhole reconstruction, the cold-rod phantom study showed minimal loss of spatial resolution in multi-pinhole systems, compared to a single-pinhole system with the same pinhole diameter. A quantitative study of neuroreceptor binding sites using a mouse brain phantom and low activity (37 MBq) showed that the multi-pinhole system outperformed the single-pinhole system by maintaining the mean and lowering the variance in the measured uptake ratio. Multi-pinhole collimation can be used to reduce the injected dose and thereby reduce the radiation exposure to the animal. Results also suggest that the nine-pinhole configuration shown in this paper is a good choice for mouse brain imaging.     

Cellular and humoral autoimmune responses against human eye muscle membrane antigen in Graves' disease

75 patients with Graves' disease (54 with ophthalmopathy) were investigated using the tests of leucocyte adherence inhibition and immune adsorption with 125I-labelled Staphylococcus Protein A, against human eye muscle "crude" membrane antigen. The results of positive leucocyte adherence inhibition (10 out of 26 vs. 1 out of 28, P less than 0.05) and anti-human eye muscle membrane antibody index (mean +/- S.D.) (1.89 +/- 1.20 vs. 0.84 +/- 0.38, P less than 0.001) showed a correlation with the patients with clinically active eye disease and the HLA-B8 antigen in Graves' ophthalmopathy (P less than 0.01). Positive leucocyte adherence inhibition was observed in 9 out of 21 cases of Graves' disease without ophthalmopathy, but its prognostic relevance has to be confirmed in the development of ophthalmopathy.     

The detection and characterization of viral-related double-stranded RNAs in tobacco mosaic virus-infected plants

The 2 M LiCl-soluble RNA fraction extracted from tobacco mosaic virus (TMV)-infected tobacco plants contains, in addition to the viral replicative form of 4 x 10(6) MW, three smaller double-stranded (ds) RNA species with apparent molecular weights (estimated by polyacrylamide gel electrophoresis, using ds RNAs as markers) of 2.25, 1.1, and 0.23 x 10(6). The synthesis of all four ds RNAs is insensitive to actinomycin D. They are completely RNase insensitive at high salt concentrations and are found both in directly inoculated and in apical tissues. In tissues incubated in the presence of 3H-uridine and actinomycin D, the three small ds RNAs accounted for 6 to 11.5% of the total radioactivity incorporated into viral ds RNA. On a molar basis, however, in apical leaves the smallest ds RNA was synthesized to almost the same level as the replicative form. By molecular hybridization, the three small ds RNAs have been shown to be of viral origin, and each contains sequences represented in the 5' end of complementary (negative strand) TMV RNA. Based on molecular weight data, none of the ds RNAs can be considered to be a ds form of the subgenomic TMV coat protein mRNA (the LMC), suggesting that it is not replicated independently. None of the small ds RNAs was found to be an endogenous product of the bound TMV RNA replicase.     

Twenty-four hour leukocyte adherence inhibition test in thyroid cancer patients

The effect of TG cell depletion taking place during 24 hour incubation on the leukocyte adherence inhibition phenomenon was investigated in patients suffering from cancer of the thyroid and healthy volunteers. The depletion coincided with the increase of the adherence inhibition if PPD was used as antigen in both groups, but the reaction to the tumour associated antigen could not be brought into relation with the depletion of TG cells.