Correlation between the parameters of contingent negative variation and characteristics of variational pulsometry in Parkinsonian patients

In patients suffering from Parkinson's disease (PD), we analyzed correlations between the parameters of contingent negative variation (CNV) and data of variational pulsometry (according to the measurements of R-R ECG intervals). Studies were carried out on 35 patients (group PD), 49 to 74 years old, with the stage of disease of 1.5 to 3.0 according to the Hoehn-Yahr international classification. In the course of CNV recording (i.e., in the state of a certain functional loading), we observed significant negative correlations between the integral magnitude (area) of this potential and indices of variational pulsometry (RMSSD, SDNN, C. var, and HF) that characterize the intensity of parasympathetic (respiratory) influences on the cardiovascular system. In the control group, such correlations were absent. We found significant correlations between the autonomic balance, CNV magnitude, and stage of PD reflecting the level of generalization of the pathological process. In the subgroup of patients with the PD stage 1.5 to 2.0, significant changes in the mean values of indices of parasympathetic influences during recording of the CNV were not observed, while in another subgroup (the PD stage 2.5 to 3.0), these values increased significantly (P < 0.05 and P < 0.01). If the estimates of the PD stage were low, the CNV area demonstrated greater values (P < 0.01). The disturbance of coordination of muscle-to-muscle interactions in the PD group is, probably, an important factor responsible for parasympathetic dysregulation and suppression of the CNV generation. We found positive correlation between the intensity of parasympathetic influences in the course of CNV recording and the level of postural disorders (r = 0.37, P < 0.05). On the contrary, the CNV magnitude demonstrated a negative correlation with the intensity of these disorders (r = −0.36, P < 0.05), as well as with the level of postural instability (r = −0.55, P < 0.001). We hypothesize that alterations of the autonomic balance and the activity of those cerebral structures, which are responsible for the motor readiness, result, to a significant extent, from weakening of the activity of the noradrenergic system due to degenerative processes developing in cells of the locus coeruleus. The impairment of the latter structure, together with degeneration of neurons of the substantia nigra and a decrease in the level of nigro-striatal dopamine, underlies the pathomorphological pattern of PD. Neirofiziologiya/Neurophysiology, Vol. 40, No. 3, pp. 242–253, May–June, 2008.     

Temperature effects on osmotic fragility, and the erythrocyte membrane

Results are reported on the temperature-dependence of intact-cell surface area, isotonic volume, hemolytic volume, and ghost steady-state surface area and volume, using several techniques of resistive pulse spectroscopy. Temperature was found not to alter the intact cell surface area permanently: the area remains constant at 130 +/- 1 micron 2, at temperatures ranging from 0 to 40 degrees C. Temperature does alter the steady-state volume of the cells, with a colder temperature inducing swelling by about 0.29 micron 3/deg. C. Such a temperature-induced volume change is sufficient to explain only approximately half of the fragility differences which result from temperature changes. The remainder was found to result from higher temperatures enabling a substantial transient increase in surface area of intact cells (up to at least 14% of 40 degrees C), with a corresponding increase in the cell's hemolytic volume (up to 21%). The hemolytic volume apparently increases linearly with temperature, since steady-state ghost volumes are found to increase linearly with the temperature at which the ghosts were produced. In the steady state (at high temperature), the membranes of electrically-impermeable resealed ghosts can remain extended by more than 10%, compared with membranes of the corresponding unhemolyzed, intact red cells.     

Stability of tissue culture medium pH as a function of autoclaving,time, and cultured plant material

Autoclaving is a standard procedure for sterilizing nutrient media for plant tissue cultures. Most tissue cultures are grown at pH 5.2 to 5.8 with pH adjustments being made prior to autoclaving. This paper reports that there are significant differences between initial pH levels and pH levels following autoclaving, particularly in the pH range of 5.7 to 8.5. This effect is noted with and without agar. In addition, we report that with time the pH of the medium drifts into the acid range. When Cucumis callus was added to the medium, the pH was changed significantly within 48 hours. The amount and direction (increase or decrease of pH) was significantly correlated with the original pH. This suggests that researchers should be wary of the true pH situation in their medium. In addition, in publications authors should specify whether their medium pH value was determined before or after autoclaving.     

The effect of whey protein hydrolyzates on the lactic acid fermentation

Summary The batch fermentation of whey permeate to lactic acid was improved markedly by the addition of enzymehydrolyzed whey protein. Acid concentrations greater than 90 g/l were achieved at a productivity of 4.3 g/l per h and a 98% substrate use. Cell mass concentration reached 6 g/l. The acid productivity achieved is somewhat higher than that typical for fermentation of whole whey. The process economics, based on in-house hydrolyzate preparation, look promising. Presented in this paper are the experimental results showing the effects of hydrolyzate concentration on acid and cell mass production.     

Structural components of sea urchin sperm nuclei

The sea urchin sperm nucleus rapidly loses its conoid morphology and becomes more voluminous and spherical upon its entry into the egg cytoplasm during fertilization. This investigation has attempted to determine what are the structural constraints placed upon the sperm nucleus, so that further investigations might determine the egg cytoplasmic factors that are responsible for modifying nuclear morphology. Isolated sperm nuclei were subjected to various extraction procedures in order to remove the majority of the proteins (histones) and also the DNA; subsequently, the residual structures were processed for and examined by electron microscopy. The data presented in this investigation demonstrate the removal of the sperm nuclear histones plus other nonhistone proteins has no effect on the conoid morphology of the sperm nucleus, yet this protein removal has a profound effect on the structure of the nuclear chromatin. It is also shown that removal of the majority of the nuclear DNA has no effect on the shape of the sperm nucleus. These results indicate that there are other components (possibly a nuclear matrix) associated with the sperm nucleus that are responsible for maintaining its conoid morphology.     

Free radicals in dicarboxylic acids: an e.s.r. study of gamma-irradiated single crystals of glutaric acid at 77 K

Electron spin resonance techniques were used to study the gamma-radiation-induced free radicals in single crystals of glutaric acid in the temperature range from 77 K to 300 K. Three different radicals are stabilized at 77 K. The decarboxylation radical is the dominant species and the other two radicals are assigned to the anion and to the substituted acetyl sigma-radical. When the temperature of the crystal is raised, these radicals disappear and the previously studied room temperature radicals appear. E.S.R.-data and the results from semi-empirical INDO-MO calculations were compared in order to elucidate the structures of the various radicals.     

Multiple forms of acetylcholinesterase from rat erythrocytes. Effect of fat-free diet.

Electrophoretic patterns of acetylcholinesterase (acetylcholine hydrolase, EC 3.1.1.7) from rat erythrocyte were studied. The enzyme was solubilized by the following treatments: a) Triton X-100, b) sodium deoxycholate, or c) ultrasonic irradiation. When the erythrocyte membrane was solubilized by Triton X-100 at concentrations higher than 0.3%, by 10 mM sodium deoxycholate, or by ultrasonic irradiation for more than 5 min, a single band of acetylcholinesterase activity appeared in the gel. Two bands of activity were stained in the gel when the membrane was solubilized by Triton X-100 at concentrations between 0.1--0.2%, or by ultrasound for 5 min. Electrophoretic patterns of acetylcholinesterase from rats fed a fat-sufficient diet were similar to those for the enzyme from animals fed a fat-free diet. The recombination of lipids with the enzyme eluted from the gels confirmed the "phenotypic allosteric desensitization phenomenon".     

Feather mites (Acari: Astigmata) and body condition of their avian hosts: a large correlative study

Feather mites are arthropods that live on or in the feathers of birds, and are among the commonest avian ectosymbionts. However, the nature of the ecological interaction between feather mites and birds remains unclear, some studies reporting negative effects of feather mites on their hosts and others reporting positive or no effects. Here we use a large dataset comprising 20 189 measurements taken from 83 species of birds collected during 22 yr in 151 localities from seven countries in Europe and North Africa to explore the correlation between feather mite abundance and body condition of their hosts. We predicted that, if wing‐dwelling feather mites are parasites, a negative correlation with host body condition should be found, while a mutualistic interaction should yield positive correlation. Although negative relationships between feather mite abundance and host body condition were found in a few species of birds, the sign of the correlation was positive in most bird species (69%). The overall effect size was only slightly positive (r =0.066). The effect of feather mite abundance explained <10% of variance in body condition in most species (87%). Results suggest that feather mites are not parasites of birds, but rather that they hold a commensalistic relationship where feather mites may benefit from feeding on uropygial gland secretions of their hosts and birds do not seem to obtain a great benefit from the presence of feather mites.     

Diffusible signals and fasciculated growth in reticulospinal axon pathfinding in the hindbrain

We have addressed the control of longitudinal axon pathfinding in the developing hindbrain, including the caudal projections of reticular and raphe neurons. To test potential sources of guidance signals, we assessed axon outgrowth from embryonic rat hindbrain explants cultured in collagen gels at a distance from explants of midbrain-hindbrain boundary (isthmus), caudal hindbrain, or cervical spinal cord. Our results showed that the isthmus inhibited caudally directed axon outgrowth by 80% relative to controls, whereas rostrally directed axon outgrowth was unaffected. Moreover, caudal hindbrain or cervical spinal cord explants did not inhibit caudal axons. Immunohistochemistry for reticular and raphe neuronal markers indicated that the caudal, but not the rostral projections of these neuronal subpopulations were inhibited by isthmic explants. Companion studies in chick embryos showed that, when the hindbrain was surgically separated from the isthmus, caudal reticulospinal axon projections failed to form and that descending pioneer axons of the medial longitudinal fasciculus (MLF) play an important role in the caudal reticulospinal projection. Taken together, these results suggest that diffusible chemorepellent or nonpermissive signals from the isthmus and substrate-anchored signals on the pioneer MLF axons are involved in the caudal direction of reticulospinal projections and might influence other longitudinal axon projections in the brainstem.