Thermodynamics of calmodulin and tubulin binding to the vinca-alkaloid vinorelbine

Vinca-alkaloids, such as vinblastine, and some of their derivatives, for example vinorelbine, are widely used in clinical therapy of leukemia and several types of tumors. Their effects are associated with the disfunctioning of the mitotic spindle, which leads to mitosis blockage and a shutting down of the cell cycle. Their primary target is tubulin; however, recent research has shown that some of the vinca-alkaloids inhibit calmodulin binding to its targets. Vinca-alkaloids binding with other proteins could be responsible for their efficiency and neuroprotection. Here, we investigated the thermodynamics of vinorelbine interactions with calmodulin and tubulin. It was determined that, unlike the other vinca-alkaloids, both vinorelbine binding sites are located in the C-domain of calmodulin and they are characterized by association constants of 4.0 × 10⁵ and 5.4 × 10⁴ M⁻¹. At the same time, the thermodynamics of vinorelbine binding to tubulin are not much different from that of other vinca-alkaloids. These results will allow us to get a better insight on the reaction mechanisms of vinca-alkaloids on a secondary protein target.     

An efficient protocol for stimulating cell development in protoplast culture of S<Emphasis Type=Italic>caevola</Emphasis>

Scaevola, characterised by unique fan-shaped flowers, is an Australian endemic ornamental having a great commercial potential. The breeding of Scaevola however is limited due to poor seed germination, therefore it is critical to understand the embryogenesis in Scaevola so as to facilitate its breeding improvement programs. Direct differentiation of embryo structures was first reported here in mesophyll protoplast cultures of Scaevola aemula. The isolated protoplasts initiated cell division when cultured in KM or MS medium. Higher plating efficiencies were observed in the medium containing a combination of NAA and BAP in contrast to 2,4-D and BAP. The formation of globular embryo structures was successfully achieved. This protoplast culture system can be utilized as an experimental platform for the study of embryogenic differentiation of cells. It may open new vistas to investigate the seed development at molecular and cellular levels in Scaevola and related Australian native plants that are well known for their low seed viability and germination.     

Statin Use and the Risk of Parkinson's Disease: An Updated Meta-Analysis

Introduction

In response to the ongoing debate over the relationship between the use of statins and the risk of Parkinson''s disease (PD), we performed a systematic review and meta-analysis of observational studies to examine their association.

Methods

We conducted a review of the literature using electronic databases supplemented by a manual search to identify potentially relevant case-control or cohort studies. Summary relative risk (RRs) and 95% confidence intervals (CIs) were calculated using a random-effects model. Sensitivity and subgroup analyses were also conducted.

Results

Eleven studies (five case-control and six cohort) with a total of 3,513,209 participants and 21,011 PD cases were included. Statin use was associated with a lower risk of PD, with a summary RR of 0.81 (95% CI 0.71–0.92). Sensitivity analysis demonstrated the robustness of results. Subgroup analyses showed that neither study design nor study region significantly influenced the effect estimates. However, subgroup studies adjusted for age or sex had a greater inverse association than did unadjusted analyses (age-adjusted RR 0.75, 95% CI 0.60–0.95; age-unadjusted RR 0.86, 95% CI 0.75–0.99 and sex-adjusted RR 0.76, 95% CI 0.59–0.98; sex-unadjusted RR 0.85, 95% CI 0.79–0.92).

Conclusions

Results of this systematic review suggest that statin use is associated with a reduced PD risk. However, randomized controlled trials and more observational studies should be performed before strong conclusions are drawn.     

Intestinal endotoxin as a trigger of type 1 diabetes mellitus

The blood serum level of intestinal flora endotoxin was studied in 45 children and adolescents aged 3–17 years with type 1 diabetes mellitus. In all the patients the endotoxin levels 2.89 ± 0.33 EU/ml) were significantly elevated compared to the control group (0.4 ± 0.03 EU/ml). A higher level of endotoxin at the disease onset (3.93 ± 0.79 EU/ml) compared to that in children afflicted with diabetes for more than two years (2.37 ± 0.27 EU/ml) gives evidence of the involvement of endotoxin in the initiation of the disease.     

Development of enzyme immunoassay of amphetamines in human biological fluids

Enzyme-linked immunosorbent assay (ELISA) for detection of amphetamines in urine was developed. The conditions for ELISA using an antigen obtained from the derivative of amphetamine and ovalbumin were optimized. It was shown that the specificity of the proposed method when used in clinical conditions corresponds to that of gas chromatography with mass spectrometric detection.     

Noninvasive estimation of the oxygen status of experimental tumors by diffuse optical spectroscopy

The potentialities of diffuse optical spectroscopy for noninvasive estimation of the oxygen status of experimental tumors have been demonstrated. The distribution of total, oxygenated, and deoxygenated hemoglobin, as well as the level of oxygen saturation of blood have been assessed using two tumor models differing in the histological structure and functional characteristics. The results obtained by the optical method have been verified by immunohistochemical examination of tissue specimens with an exogenous hypoxia marker pimonidazole.     

Verification of a decrease in the rigidity of the phage λ DNA polymeric chain in low ionic strength aqueous solutions by testing the polymer-polymer interlink interactions

Changes in the rigidity of the polymeric chain of phage λ double-strand DNA have been studied by laser correlation spectroscopy. It was shown that, as the ionic strength increases, the effect of the screening of the hydrodynamic interaction of the links of the polymeric chain specific for polymeric coils arises in a DNA solution. It is assumed that the screening occurs when the threshold of the overlapping of DNA coils is achieved. The overlapping of coils is the result of a previously observed significant rise of DNA coil size from abnormally small DNA coils in low ionic strength buffers (about 10⁻² M Na⁺ or less) to maximum possible large coils in the 5SSC and 5SSC-like buffers. Further analysis of the far interlink interactions in linear lambda phage DNA coils in similar buffers at pH 7 and 4 confirms the earlier proposal about the role of H+ ions in the appearance of abnormally small DNA coils. The abnormal decrease in the DNA coil size in low ionic strength buffers is not a specific feature of λ phage DNA only.     

Biological activity of water-soluble nanostructures of dihydroquercetin with cyclodextrins

The biological properties of dihydroquercetin (DHQ) modified by including it into the ring of β-cyclodextrin (β-CD) to give it more water-soluble properties have been investigated. It was shown that the peroral administration of the DHQ/β-CD complex provides a long increase of DHQ concentration in rat blood (up to 7.5 h), and, unlike pure DHQ, the complex does not accumulate in the liver. As DHQ is released from the complex, it penetrates into liposome membranes, changing their thermodynamic characteristics. DHQ decreases the specific heat absorption, enthalpies, and temperature maximum of lipid melting and increases the transition half-width. This property is used to estimate the stability of the DHQ/β-CD complex. It was shown that complex DHQ/β-CD is not stable, and DHQ molecules slowly leave the complex in water environment. Seven and a half hours after the peroral injection of drugs, DHQ was found in the blood plasma of rats to which water-soluble complex DHQ/βCD was injected and in the liver of rats to which free DHQ was injected. Thus, DHQ/βCD not only is a more water-soluble complex but also it slowly releases DHQ, supporting long a low concentration of the free form of DHQ and providing the penetration of DHQ into the blood stream. After several weeks of feeding old mice with antioxidants, the activity of mitochondrial enzymes was restored to the level observed in young animals.