Effect of pH and Glucose on the Stability of α-lactalbumin

The objective of this study is to understand the influence of pH and effect of cosolvent (glucose) on the stabilization of bovine α-lactalbumin by using ultrasonic techniques. Values of density, ultrasonic velocity and viscosity were measured for bovine α-lactalbumin (5 mg/ml) dissolved in phosphate buffer (pH 2, 5, 7, 9 and 12) solutions mixed with and without the cosolvent at 30 °C. These measurements were used to calculate few thermo-acoustical parameters such as adiabatic compressibility, intermolecular free length, acoustic impedance, relaxation time, relative association constant, the partial apparent specific volume and the partial apparent specific adiabatic compressibility for the said systems. The obtained results revealed a strong comparison between the effects of acidic and alkaline pH values on protein denaturation, i.e., the acidic pH are instantaneous and are of less magnitude whereas alkaline pH are slower but sharper. Further the present study supports the fact that the presence of glucose stabilizes α-lactalbumin against denaturation due to pH variation, which may be due to the strengthening of non-covalent interactions and the steric exclusion effect.     

Effect of Diabetes Mellitus Type 2 on Salivary Glucose – A Systematic Review and Meta-Analysis of Observational Studies

Background

Early screening of type 2 diabetes mellitus (DM) is essential for improved prognosis and effective delay of clinical complications. However, testing for high glycemia often requires invasive and painful blood testing, limiting its large-scale applicability. We have combined new, unpublished data with published data comparing salivary glucose levels in type 2 DM patients and controls and/or looked at the correlation between salivary glucose and glycemia/HbA1c to systematically review the effectiveness of salivary glucose to estimate glycemia and HbA1c. We further discuss salivary glucose as a biomarker for large-scale screening of diabetes or developing type 2 DM.

Methods and Findings

We conducted a meta-analysis of peer-reviewed published articles that reported data regarding mean salivary glucose levels and/or correlation between salivary glucose levels and glycemia or HbA1c for type 2 DM and non-diabetic individuals and combined them with our own unpublished results. Our global meta-analysis of standardized mean differences on salivary glucose levels shows an overall large positive effect of type 2 DM over salivary glucose (Hedge''s g = 1.37). The global correlation coefficient (r) between salivary glucose and glycemia was large (r = 0.49), with subgroups ranging from medium (r = 0.30 in non-diabetics) to very large (r = 0.67 in diabetics). Meta-analysis of the global correlation between salivary glucose and HbA1c showed an overall association of medium strength (r = 0.37).

Conclusions

Our systematic review reports an overall meaningful salivary glucose concentration increase in type 2 DM and a significant overall relationship between salivary glucose concentration and associated glycemia/HbA1c values, with the strength of the correlation increasing for higher glycemia/HbA1c values. These results support the potential of salivary glucose levels as a biomarker for type 2 DM, providing a less painful/invasive method for screening type 2 DM, as well as for monitoring blood glucose levels in large cohorts of DM patients.     

The Combined Effect of Glucose and β-Hydroxybutyrate on the Membrane Potential of Synaptosomal Mitochondria

Biophysics - Abstract—The ketogenic diet is used as a treatment for different brain diseases. It involves replacement of dietary carbohydrates with fat, which leads to production of ketone...     

Studies on the Effect of Water-Soluble Polymers on Drug–Cyclodextrin Complex Solubility

The effect of complexation of irbesartan (IRB), a practically water-insoluble drug, with cyclodextrins in presence of different concentrations of water-soluble polymers (PEG 4000 and PVP K-90) on the dissolution rate of the drug has been investigated. Phase solubility studies were carried out to evaluate the solubilizing power of βCD in association with water-soluble polymers towards IRB and to determine the apparent stability constant (K _S) of the complexes. Improvement in K _S value for ternary complexes (IRB–βCD–polymers) clearly proved the benefit on the addition of water-soluble polymer to increase complexation efficiency. The dissolution rate of the drug from ternary systems containing PEG 4000 and PVP K-90 was higher as compared to the binary system. An optimum increase in the dissolution rate of the drug was observed at a polymer concentration of 5% w/w for PVP K-90 and 10% w/w for PEG 4000. DSC, FTIR, SEM, and XRD studies were carried out to characterize the complexes.     

Effect of cadmium on physiological parameters of cereal and millet plants—A comparative study

Metal load is an abiotic stress that becomes stronger by continual industrial production, wastage, and long-range transport of contaminants. It deteriorates the conditions of agricultural soil that leads to lower growth of cereals as well as decreasing nutritional value of harvested grains. Cadmium (Cd) entry by food chain also affects the health of population. The present study is focused on finding out the superior cereal variety under increasing Cd regime. The plants were grown in increasing Cd levels (0–1000 µM) in the medium and were investigated on 15th day of the exposure. Various parameters like antioxidative enzymes and osmoprotectant levels were studied in both roots and shoots. Cd accumulation in plant organs was determined by atomic absorption spectrophotometry (AAS). Analysis of stress tolerance mechanisms through reactive oxygen species (ROS) scavenging and better partitioning of Cd in roots indicated kodo millet to be more stress tolerant than wheat.     

Effect of Glucose on the Lactoferrin’s Conformation and its Effect on MC 3T3-E1 Cell Proliferation

The objective of this research was to investigate the influence of glucose on bovine lactoferrin’s (LF) conformation, thermodynamic stability and osteoblastic cell proliferation. The conformation and thermodynamic stability of LF was detected by spectroscopic and differential scanning calorimetry (DSC). The osteoblastic cell proliferation of LF at physiological concentrations (100 μg/ml) was measured by BrdU incorporation. The binding constant between glucose and LF is KSV = 5 × 10⁻³, and Tyr residues of LF were located in a more hydrophobic environment, while Trp residues were located in a more hydrophilic environment. LF with glucose had increased α-helix and β-sheet contents by 6 and 14 %, respectively. It showed a two-step denaturation of LF. There was a gradual changs in the denaturation temperature and the calorimetric enthalpies (ΔHcal) with a growing concentration of glucose. It has also revealed that glucose dose dependently reduced the ability of LF to increase MC 3T3-E1 cell proliferation. Increasing the binding with glucose, LF might cause to change its native state, which reduced the stimulation activity of osteoblasts cell proliferation.     

Effect of inter-renal aortic coarctation-induced hypertension on function and expression of vascular α(1A)- and α(1D)-adrenoceptors

We investigated the effect of inter-renal aortic coarctation on the function and expression of vascular α(1A)- and α(1D)-adrenoceptors and plasma angiotensin II (ATII) in rats. Male Wistar rats, either sham operated (SO), or with aortic coarctation for 7 (AC7) and 14?days (AC14) were used for agonist-induced pressor responses in vehicle (physiological saline)- and antagonist-treated anesthetized animals, immunoblot analysis (α(1A)- and α(1D)-adrenoceptor in aorta and caudal arteries), and immunoassay (plasma ATII). The α(1D)-adrenoceptor antagonist, BMY-7378 (BMY) blocked noradrenaline-induced responses in the order SO?> AC7?? AC14; in contrast, the α(1A)-adrenoceptor antagonist RS-100329 (RS), produced a marginal shift to the right of the dose-response curve to noradrenaline, along with a strong decrease of the maximum pressor effect in the order SO?> AC7?= AC14. The potency of the α(1A)-adrenoceptor agonist A-61603 increased in rats with AC14, and responses were inhibited by RS in the order AC14?> AC7?> SO. In aorta, α(1D)-adrenoceptor protein increased in AC7 and decreased in AC14; α(1A)-adrenoreceptor protein increased in the caudal artery of AC7 and returned to control values in AC14. Plasma ATII increased in AC7 and AC14, compared with SO rats. These results suggest an early and direct relationship between ATII and α(1D)-adrenoreceptors in the development of hypertension in this experimental model.     

The Toxic Effect of Lithium Ion on Neurons (PC12 cells) and Aβ42 Molecules

In this study, the neurotoxicity of Li ion and its effect on the morphologies of Aβ₄₂ molecules were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays, fluorescence (FL), atomic force microscopy (AFM), and circular dichroism (CD) spectroscopy. MTT assays show that Li ion with a dosage level lower than 50 mg/l did not show detectable cytotoxicity on pheochromocytoma (PC12) cells whereas a dosage level higher than 100 mg/l resulted in significant cytotoxicity. The interaction between Aβ₄₂ and Li ion occurs, and the quenching effect of Li ion on the fluorescence emission of AΒ₄₂ is found to be concentration dependent, suggesting that Li ion can bind to the Aβ₄₂ molecules. CD results suggest that a more incompact conformation state will be adopted upon the interaction between Aβ₄₂ and Li ion. According to AFM images, Li ion could induce the formation of the fibrils after incubation for 3 or 5 days. The formation of the oligomer and fibrils originates from the strong interactions between Aβ₄₂ and Li ion. Li ion could accelerate the random coil Aβ₄₂ monomers aggregating into the β-sheet fibrils, which would induce the neurotoxic effect.     

Effect of 24-epibrassinolide on biomass, growth and free proline concentration in Spirulina platensis (Cyanophyta) under NaCl stress

In this study, biomass, growth and free proline concentration were investigated in Spirulina platensis treated with different concentrations of NaCl (50, 100, 150, and 200 mM) and 24-epibrassinolide (24-epiBL) hormone (0.5, 1.0, and 3.0 μM) over 5 days. As a result of analysing the cultures under salinity stress, it was determined that biomass and growth rate decreased significantly, while proline concentration increased considerably under salinity stress. The increase in the concentration of proline suggests a role in response to NaCl stress. Among the cultures treated with different concentrations of 24-epiBL, maximum growth was determined at the cultures at 1.0 μM 24-epiBL. Algal growth was also greater at the 0.5 and 3.0 μM concentrations of 24-epiBL with respect to control cultures. With respect to control, 24-epiBL affected growth rate and biomass positively, but proline concentration did not change. Among the cultures supplied with different combinations of NaCl and 24-epiBL, growth rate increased in 150/0.5 and 150/3.0 mM/μM concentrations, but was maximal for the culture containing 150/1.0 mM/μM combination. The increase in algal growth suggests a role for 24-epiBL in partially alleviated to NaCl stress. These results suggest that 24-epiBL may have a protective role for S. platensis reducing the inhibitor effects of salinity stress.     

Effect of competition on the demography of planktonic cladocerans — Daphnia and Diaphanosoma

Summary Isolated and mixed continuous cultures of Daphnia hyalina and Diaphanosoma brachyurum in lake water were maintained under laboratory conditions to elucidate demographic effects of competition. Population dynamics curves were obtained. Interspecific competition was revealed by the decrease in the average density of animals in the mixed versus isolated cultures and by the extinction of one species in the presence of the other. Within the first 50 days either Diaphanosoma (4 cases) or Daphnia (1 case) was the superior competitor, depending on the initial conditions. Further cultivation resulted in the extinction of Diaphanosoma in the mixed cultures. There were no statistically significant differences between the maximum rates of population increase (r _m ) in Daphnia and Diaphanosoma at the concentration of edible algae about 2·10⁵ m³ml^-1(0.293 and 0.286 days^-1, respectively). Time lags for density-dependent parameters of the populations were evaluated by means of rank cross-correlations. Regardless of the species identity the time lags of fecundity, birth rate, and the rate of population growth were significantly higher in the superior competitor. The initial conditions of culturing affected the time lags which in their turn influenced the outcome of the interaction. Enhanced competitive ability due to the maximized time lags in Daphnia was not associated with the loss of population stability. Conversely, it brought about destabilization of Diaphanosoma populations which seemed to be the ultimate cause of its extinction observed in the end of the experiment. Time lag of the population growth rate was well predicted based on the half-sum of time lags in birth and death rates (r²=0.80, P<0.001). Daphnia responded to competition with a sharp shortening of the time lags of fecundity, birth rate, and the population growth rate. It increased clutch size and showed inverse relationship between the fecundity time lag and average fecundity even though it was strongly suppressed by Diaphanosoma. The competitive ability was not related to the percentage of adults in the populations. In contrast to the current belief the major result of interspecific competition in the experiment was not a decrease in the rate of population growth but was a reduction in population time lags.