Hepatic Insulin-Positive Cells and Major Transcription Factors (PDX1, MAFA,NGN3) in Rat Models of Type 1 and Type 2 Diabetes Mellitus

Journal of Evolutionary Biochemistry and Physiology - Due to a high occurrence of diabetes mellitus (DM) and its complications, insulin-positive cells detected in different organs are of great...     

Mechanism of the suppression of the spinal pain syndrome by serotonin derivatives

The ability of serotonin derivatives to stimulate cAMP accumulation in isolated nerve terminals and lumbar enlargement of the spinal cord of normal rats was compared. The effect of the compounds on the intensity of spinal pain syndrome was also assessed. It has been established that substitutes injected into NH2-group of serotonin in 5-OH position attenuate the ability to stimulate cAMP accumulation in synaptosomes, with the effect more pronounced with substitutes of larger volume. A certain correlation between the ability of serotonin derivatives to stimulate adenylate cyclase in vivo and in vitro, on the one hand, and their analgetic effect, on the other hand, is suggested.     

The Effects of a Low-Frequency Electric Field on Recombinant Luciferase Activity

Biophysics - Studies on the effects of an electromagnetic field on the activity of recombinant luciferase in the luciferase–luciferin–ATP-Mg2+ system were conducted. The enzymatic...     

Inhibitory effect of the amygdala on alimentary-conditioned reflexes in the dog

In experiments on dogs, changes of conditioned alimentary reflexes were studied under stimulation (50-100 mcA, 1, 40, 100 imp/s, 0.5 ms) of the basolateral area of amygdala before and after electrolytic ablation (5 mA, 60 s) of the head of the caudate nucleus. Stimulation of the amygdala, which elicited inhibition of conditioned secretory reflexes and prolongation of latencies in intact dogs leads to opposite - activating - influences after destruction of the caudate nucleus head. A conclusion is made on the participation of neurophysiological and neurochemical mechanisms of the caudate nucleus in transmission of inhibitory effects of the amygdala on alimentary conditioned reflexes.     

The lepidopteran mitochondrial control region: structure and evolution

For several species of lepidoptera, most of the approximately 350-bp mitochondrial control-region sequences were determined. Six of these species are in one genus, Jalmenus; are closely related; and are believed to have undergone recent rapid speciation. Recent speciation was supported by the observation of low interspecific sequence divergence. Thus, no useful phylogeny could be constructed for the genus. Despite a surprising conservation of control-region length, there was little conservation of primary sequences either among the three lepidopteran genera or between lepidoptera and Drosophila. Analysis of secondary structure indicated only one possible feature in common--inferred stem loops with higher-than-random folding energies-- although the positions of the structures in different species were unrelated to regions of primary sequence similarity. We suggest that the conserved, short length of control regions is related to the observed lack of heteroplasmy in lepidopteran mitochondrial genomes. In addition, determination of flanking sequences for one Jalmenus species indicated (i) only weak support for the available model of insect 12S rRNA structure and (ii) that tRNA translocation is a frequent event in the evolution of insect mitochondrial genomes.      

Glutamine repeats and inherited neurodegenerative diseases: molecular aspects

Several dominantly inherited, late onset, neurodegenerative diseases are due to expansion of CAG repeats, leading to expansion of glutamine repeats in the affected proteins. These proteins are of very different sizes and, with one exception, show no sequence homology to known proteins or to each other; their functions are unknown. In some, the glutamine repeat starts near the N-terminus, in another near the middle and in another near the C-terminus, but regardless of these differences, no disease has been observed in individuals with fewer than 37 repeats, and absence of disease has never been found in those with more than 41 repeats. Protein constructs with more than 41 repeats are toxic to E. coli and to CHO cells in culture, and they elicit ataxia in transgenic mice. These observations argue in favour of a distinct change of structure associated with elongation beyond 37–41 glutamine repeats. The review describes experiments designed to find out what these structures might be and how they could influence the properties of the proteins of which they form part. Poly- -glutamines form pleated sheets of β-strands held together by hydrogen bonds between their amides. Incorporation of glutamine repeats into a small protein of known structure made it associate irreversibly into oligomers. That association took place during the folding of the protein molecules and led to their becoming firmly interlocked by either strand- or domain-swapping. Thermodynamic considerations suggest that elongation of glutamine repeats beyond a certain length may lead to a phase change from random coils to hydrogen-bonded hairpins. Possible mechanisms of expansion of CAG repeats are discussed in the light of looped DNA model structures.     

Active immunization to exogenous and endogenous antidepressants. The formation of antibodies to biogenic amines and peptide regulators

The active immunization of rabbits and white rats to antidepressant sydnophen results in the formation of antibodies binding norepinephrine, dophamine, serotonine as well peptide regulatory compounds: substance P, pynorphine, vasopressin and beta-endorphin. The immunization against endogenic antidepressant thyroliberin induces the formation of antibodies to the same biogenic amines and to the gamma-aminobutyric acid, oxytocin and leu encephalin. The data obtained are discussed in connection with some physiological and biochemical changes found earlier during immunization to antidepressants.