Experimental modeling of preclinical and clinical stages of Parkinson��s disease

Degeneration of dopaminergic (DAergic) neurons of the nigrostriatal system is the key stage in the pathogenesis of Parkinson's disease. The first symptoms of this disease are observed after degeneration of 70-80% neurons, which occurs over 20-30 years. The clinical stage of Parkinson's disease begins after this period. Late diagnostics of Parkinson's disease contributes to low efficiency of therapy for this disorder. Detailed study of the pathogenesis and development of preclinical diagnostic methods for Parkinson's disease are the urgent problems. This work was designed to develop a new experimental model of the preclinical and clinical stages of the disease. Experimental modeling was performed on C57Bl/6 mice using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). This agent is converted into the MPP(+)-neurotoxin in brain DAergic neurons. We showed that MPTP in a dose of 4 mg/kg has no effect on the nigrostriatal DAergic system. MPTP in a dose of 8-16 mg/kg produced the toxic effect only on DAergic axons, which simulates the preclinical stage of Parkinson's disease. MPTP in a dose of 20-40 mg/kg had the toxic effect on neuronal axons and bodies, which simulates the clinical stage of Parkinson's disease. The data suggest that progressive degeneration of DAergic neurons is accompanied by activation of compensatory mechanisms for functional deficiency of these cells.     

The effects of irradiation by 12C carbon ions on monoamine exchange in several rat brain structures

Rats were irradiated with carbon ions (¹²C) in a Nuklotron accelerator. The irradiation dose was 1 Gy, the energy of the ions was 500 MeV/nuclon, and the linear energy transmission (LET) was 10.6 keV/micron. The animals were decapitated 1 day after irradiation. We isolated the prefrontal cortex, nucleus accumbens, hypothalamus, hippocampus, and striatum, where we determined the concentrations of monoamines and their metabolites. Strong changes were observed in three structures, viz., the prefrontal cortex, nucleus accumbens, and hippocampus. However, significant changes were found in the prefrontal cortex and weaker changes were seen in the nucleus accumbens, whereas changes were insignificant in the hippocampus. This reaction may be related to the fact that the animals were examined on the 2nd day after irradiation. It was shown that an increase in the interval between irradiation and examination of animals results in enhancement of the effects of radiation treatment. The experiments revealed the high sensitivity and reactivity of the prefrontal cortex, which we relate to the key role of this structure in vitally critical processes of behavior.     

Parasitic diseases in the USSR and tasks in their prevention

Paper presents the data on the morbidity pattern of parasitic diseases in the USSR as well as on the trends in ascariasis, trichocephaliasis and hymenolepiasis infection rates. Problems of improving the prophylactic and antiepidemic measures are discussed with regard both to practical parasitology and investigations.     

Standardization of extracellular vesicle measurements by flow cytometry through vesicle diameter approximation

Essentials

• Platelet extracellular vesicles (EVs) concentrations measured by flow cytometers are incomparable.
• A model is applied to convert ambiguous scatter units to EV diameter in nanometer.
• Most included flow cytometers lack the sensitivity to detect EVs of 600 nm and smaller.
• The model outperforms polystyrene beads for comparability of platelet EV concentrations.

Summary

Background

Detection of extracellular vesicles (EVs) by flow cytometry has poor interlaboratory comparability, owing to differences in flow cytometer (FCM) sensitivity. Previous workshops distributed polystyrene beads to set a scatter‐based diameter gate in order to improve the comparability of EV concentration measurements. However, polystyrene beads provide limited insights into the diameter of detected EVs.

Objectives

To evaluate gates based on the estimated diameter of EVs instead of beads.

Methods

A calibration bead mixture and platelet EV samples were distributed to 33 participants. Beads and a light scattering model were used to set EV diameter gates in order to measure the concentration of CD61–phycoerythrin‐positive platelet EVs.

Results

Of the 46 evaluated FCMs, 21 FCMs detected the 600–1200‐nm EV diameter gate. The 1200–3000‐nm EV diameter gate was detected by 31 FCMs, with a measured EV concentration interlaboratory variability of 81% as compared with 139% with the bead diameter gate. Part of the variation in both approaches is caused by precipitation in some of the provided platelet EV samples. Flow rate calibration proved essential because systems configured to 60 μL min^?1 differed six‐fold in measured flow rates between instruments. Conclusions EV diameter gates improve the interlaboratory variability as compared with previous approaches. Of the evaluated FCMs, 24% could not detect 400‐nm polystyrene beads, and such instruments have limited utility for EV research. Finally, considerable differences were observed in sensitivity between optically similar instruments, indicating that maintenance and training affect the sensitivity.

     

Comparative evaluation of bioglass with calcium sulphate β-hemihydrate for the treatment of intraosseous defects—a clinico-radiological study

Background

The aim of the present clinical and radiological study was to compare bioglass and calcium sulphate β-hemihydrate in the treatment of intraosseous defect in chronic periodontitis.

Method

A total of 50 subjects with bilaterally symmetrical periodontal osseous defects with probing pocket depth = 5 mm and intraosseous defects ≥ 3 mm as seen on the radiographs were undertaken for the study. In one site (group A) bioactive glass was placed in defect and in contralateral site (group B) calcium sulphate β-hemihydrate was used in the defect site.

Results

Clinical improvement was noted in all patients at the end of study. Both the groups showed reduction in probing pocket depth, increase in clinical attachment level, and reduction in osseous defect. Both materials were effective in achieving osseous gain.

Conclusion

The osseous gain in group A subjects was 58.93%, whereas in group B subjects it was 48.56%. Calcium sulphate β-hemihydrates showed promising results and were cost effective.     

Multimeric composition of endothelial cell-derived von Willebrand factor

The multimeric composition of human endothelial cell (EC)-derived von Willebrand factor (vWF) was studied using SDS-agarose gel electrophoresis and autoradiography. Two multimers were found in lysates prepared from confluent cultures of human umbilical vein endothelial cells. The smaller multimer had a molecular weight (mol wt) of approximately 950 Kd, while the second was larger than those seen in plasma. When electrophoresis was performed using the discontinuous buffer system of Ruggeri and Zimmerman, the small multimer consisted of a single band migrating with the slowest-moving component of the corresponding plasma triplet. The large EC-vWF multimer was detected in culture media conditioned with EC monolayers for ten minutes. It remained the only multimer in media conditioned for up to three days. Calcium ionophore A23187 increased the amount of the large vWF multimer released into the culture media, but did not change its multimeric composition. The small multimer was never detected in the EC- conditioned media. These findings suggest that (1) a large, fully polymerized multimer of vWF is released from the ECs, while the small multimer probably represents a major intermediate component in the process of multimerization, and (2) plasma vWF multimers are probably generated from the large endothelial vWF after it is released into the circulation.