Morphological restructuring of the cellular elements of the ventral tegmental area in selective damage to the catecholaminergic systems of the brain

Electron microscopical investigation of the ventral tegmental area at various time after administration of a specific neurotoxin 6-hydroxydopamine made it possible not only to reveal catecholamine reactive elements, but also those structural reorganizations in them, that are dependent on the lesion of the catecholaminergic systems, including certain changes in the receptor apparatus. Dark neurons with the change of different organelles preserve for a long time, up to 2.5 months. Reactive and destructive reorganizations of some axons, terminal buttons and postsynaptic poles of the ventral tegmental area are accompanied with certain functional disturbances, observed both experimentally and at a pathological process. The results of the work demonstrate that under conditions of the model experiments there is a possibility to study various stages of pathogenesis of a number of nervous-psychical diseases, connected or accompanied with disorders in certain mediator systems.     

Reaction of neurons of the cerebral cingular area in rats to damage of the central monoaminergic systems]

Intracisternal injection of specific neurotoxins 6-oxydopamine and 5,7-dioxytryptamine, producing certain disorders in catecholaminergic and serotoninergic systems respectively, is accompanied with some ultrastructural rearrangements in the proper neurons of the rat cerebral cingular cortex. In the experimental material an essential increase in the amount of intranuclear inclusions--vacuole- and myelin-like--of fibrillar origin is observed. More often than in the control connection of the endoplasmic reticulum with the nuclear membrane is noted. Hypertrophy of cisterns in the Golgi complex, abundance of coated vesicles in its region, dilatation of cisterns of the endoplasmic reticulum are observed. The character of the ultrastructural rearrangements demonstrates certain changes in activity of metabolic processes of these cells, the changes being more pronounced in the case, when the cerebral serotoninergic system is damaged. The reaction of the cerebral cingular zone to injection of neurotoxins is characterized with a selective manifestation and is restricted with certain nervous cells of the II-V layers. According to their ultrastructural organization, these neurons can be considered as stellate and pyramidal.     

基于分组码模型的DNA序列编码特性分析

基于差错控制原理,将遗传信息中由海量碱基构成的DNA序列看作经过编码而获得的具有某种编码特性的编码序列。在此基础上,将编码理论中分组码的分析方法用于对DNA序列进行分析,选用了（6,3）分组码对三种原核生物和两种真核生物DNA序列进行分析,在ORF起始端和结束端观察到明显的码间距离变化。证明该方法对DNA序列分析有较好的指导作用。     

Ultrastructure of the parietal region of the brain after selective damage of the serotoninergic system

The selective lesion of the afferent serotoninergic system by means of intracisternal administration of 5,7-dihydroxytryptamine produces certain structural rearrangements in a part of cellular elements and in various parts of the neuropil of the neocortical parietal area. The deficiency of serotoninergic innervation influences the metabolic processes. This is evident from the change in the structure of protein synthesizing apparatus in a number of postsynaptic neurons. It is possible that the structural rearrangements observed in the serotoninergic and in the conjugated to it mediatory systems make the base of functional disorders in the neocortex and are accompanied with certain changes in the integrative activity of the brain.     

Methodological aspects in the study of the natural foci of zoonoses

Conceptions of different authors on the natural focus of zoonosis infections are analysed and an improved definition of this phenomenon is proposed. The natural focus of disease is the antropoecosystem of certain hierarchic level (biosocial system), where the existence and appearance of the infection agent is supported and the disease is realized in people at certain infection rate.     

Structure of the neuromuscular spindles in the tongue of human fetuses

The dynamics in development of some components--of the neuromuscular spindles in the human fetus and newborn tongues have been studied by means of certain general and neurohistological methods with elements of morphometry. During the whole prenatal period of the human life, there is a certain synchronism in the development of the lingual proper muscles and the neuro-muscular spindles. Certain integration in the development of the neuro-muscular spindles is observed in 4-6-month-old fetuses; in 8-9-month-old fetuses and in newborns it is substituted for heterochronicity. By the time of birth, the muscle spindle contractile elements are supplied with a more differentiated efferent innervation. The latter actively effects the morphological state of the intrafusal muscle fibers and forms a base for functional activity of the tongue.     

A model for the spread of an epidemic

A temporally continuous and spatially discrete stochastic model for the spread of an epidemic within some set of holdings is constructed. A recursion formula is given for the probability that a certain set of holdings is infected at a certain moment. Moreover, under an additional condition (which will always be satisfied in practice) a formula for the expected value and the variance of the moment when a certain holding is infected the first time is given.     

Iron-sulphur proteins: Their possible place in the origin of life and the development of early metabolic systems

A review is made of certain features of the biology and chemistry of the iron-sulphur proteins which suggests that these proteins may be descended from an ancestral form or form swhich arose very early in the development of biological metabolic systems (the origin of life). If this hypothesis is correct it would suggest that this class of proteins developed during the epoch in which the Earth's atmosphere was reducing in nature and that the relative facility with which the active site of certain contemporary iron-sulphur proteins is experimentally reconstituted may have played a part in their evolutionary development.     

Cholesterol and the interaction of proteins with membrane domains

Cholesterol is not uniformly distributed in biological membranes. One of the factors influencing the formation of cholesterol-rich domains in membranes is the unequal lateral distribution of proteins in membranes. Certain proteins are found in cholesterol-rich domains. In some of these cases, it is as a consequence of the proteins interacting directly with cholesterol. There are several structural features of a protein that result in the protein preferentially associating with cholesterol-rich domains. One of the best documented of these is certain types of lipidations. In addition, however, there are segments of a protein that can preferentially sequester cholesterol. We discuss two examples of these cholesterol-recognition elements: the cholesterol recognition/interaction amino acid consensus (CRAC) domain and the sterol-sensing domain (SSD). The requirements for a CRAC motif are quite flexible and predict that a large number of sequences could recognize cholesterol. There are, however, certain proteins that are known to interact with cholesterol-rich domains of cell membranes that have CRAC motifs, and synthetic peptides corresponding to these segments also promote the formation of cholesterol-rich domains. Modeling studies have provided a rationale for certain requirements of the CRAC motif. The SSD is a larger protein segment comprising five transmembrane domains. The amino acid sequence YIYF is found in several SSD and in certain other proteins for which there is evidence that they interact with cholesterol-rich domains. The CRAC sequences as well as YIYF are generally found adjacent to a transmembrane helical segment. These regions appear to have a strong influence of the localization of certain proteins into domains in biological membranes. In addition to the SSD, there is also a domain found in soluble proteins, the START domain, that binds lipids. Certain proteins with START domains specifically bind cholesterol and are believed to function in intracellular cholesterol transport. One of these proteins is StAR-D1, that also has a mitochondrial targeting sequence and plays an important role in delivering cholesterol to the mitochondria of steroidogenic cells.     

Morphological aspects of the science of human ecology

Human ecology is the science on interaction of the man with the environment including the social surrounding. In the human ecological morphology biogenic and sociogenic peculiarities are distinguished; they are formed in the phylo- or ontogenesis. Peculiarities of the body integument, proportions, development of the fat component of the body mass etc. are related with the biogenic signs of the phylogenic origin, since they are connected with life in certain climato-natural conditions. These signs have certain analogues among Mammalia. The sociogenic signs of the phylogenic origin include complexes of bepedality, labour and informative-speech activity. They are characteristic for the human being only. The sociogenic peculiarities of the ontogenic origin include certain changes of the organism connected with professional and sporting activities. According to the human organism state, observed in dynamics, it is possible to judge on biogenic and sociogenic consequences of the environmental influences. For this purpose the data of anthropometric observations in newborn are considered to be important. The role of the biogenic changes is followed in the example of shifts of the body dimensions in time, connected with the solar activity cycles; the sociogenic changes are considered in an example of growth processes under conditions of different gas-pollution of the atmosphere with industrial waste.     

Necessary and sufficient conditions for the existence of certain quadratic invariants under a phylogenetic tree.

Invariants are functions of the probabilities of state configurations among lineages, with expected values equal to zero under certain phylogenies. For two-state sequences, the existence of certain quadratic invariants requires a symmetric substitution model. For sequences with more than two states, the necessary condition for the existence of certain quadratic invariants in terms of independent events is much stronger than symmetry. For DNA sequences, only three parameters are allowed in the substitution model, which includes Kimura's two-parameter model as a special case.     

Morphological changes in the filtration-reabsorption barrier of the remaining kidney after its denervation and disordered lymph outflow

An electron microscopical investigation on combined effect of denervation and disturbance of lymphatic outflow to structural elements of the FRB in the preserved kidney after contralateral nephrectomy has been performed on 20 mature white rats in 3, 30, 180, 360 days. In 3 days in the cellular components of the FRB cytoplasmic structures are at the state of functional strain and overstrain. Hemostasis is observed in glomeruli and in peritubular capillaries, as well as edema of the interstitial connective tissue. In 30 days certain signs of hyperplasia and hypertrophy of intracellular structures appear in the components of the FRB. However, later (in 180, 360 days) certain tendency to predominance of processes of functional strain in the intracellular structures with their certain destruction and reaction of the connective stroma is observed.     

Characteristics of the wall of the 3d cerebral ventricle in rats from the viewpoint of age

The results of the light-, electron microscopic and cytophotometric investigation performed in the wall of the third cerebral ventricle are presented. It includes the ciliar, tanycytar ependyma and subependymal layer in male rats of three age groups (immature--1 month, mature--8-10 months and old--24-26 months of age). A certain decrease in the arrangement density of cellular elements of the ventricular wall is noted with age. A depressed functional activity of the ciliar ependymocytes is revealed with ageing. At the same time, some compensatory-adaptive rearrangements develop; they counteract age decrease of the function. A suggestion is made that the drenage function of the ciliar ependymal area is disturbed with age. Specific age features of the ultrastructure of the blood capillaries situating subependymally are revealed. The age changes of ependymocytes and tanicytes, as well as those of certain groups of tanycytes are not unitypical; this speaks in favour of their different functional role.     

On Interrelations between Temporal Parameters of the Calling Song of the Cricket Gryllus bimaculatus

Based on analysis of the temporal dynamics of parameters of the calling song in male crickets Gryllus bimaculatus, a conclusion has been made about the existence of a certain correlation between the number of pulses in chirps, on one hand, and chirp repetition periods and interchirp intervals, on the other hand. It is suggested that this correlation reflects a certain process running in the nervous system of a singing male with variable intensity that depends on both the external and the internal, including genetic, factors.     

Involvement of the molecular chaperone Ydj1 in the ubiquitin-dependent degradation of short-lived and abnormal proteins in Saccharomyces cerevisiae.

In Escherichia coli and mitochondria, the molecular chaperone DnaJ is required not only for protein folding but also for selective degradation of certain abnormal polypeptides. Here we demonstrate that in the yeast cytosol, the homologous chaperone Ydj1 is also required for ubiquitin-dependent degradation of certain abnormal proteins. The temperature-sensitive ydj1-151 mutant showed a large defect in the overall breakdown of short-lived cell proteins and abnormal polypeptides containing amino acid analogs, especially at 38 degrees C. By contrast, the degradation of long-lived cell proteins, which is independent of ubiquitin, was not altered nor was cell growth affected. The inactivation of Ydj1 markedly reduced the rapid, ubiquitin-dependent breakdown of certain beta-galactosidase (beta-gal) fusion polypeptides. Although degradation of N-end rule substrates (arginine-beta-gal and leucine-beta-gal) and the B-type cyclin Clb5-beta-gal occurred normally, degradation of the abnormal polypeptide ubiquitin-proline-beta-gal (Ub-P-beta-gal) and that of the short-lived normal protein Gcn4 were inhibited. As a consequence of reduced degradation of Ub-P-beta-gal, the beta-gal activity was four to five times higher in temperature-sensitive ydj1-151 mutant cells than in wild-type cells; thus, the folding and assembly of this enzyme do not require Ydj1 function. In wild-type cells, but not in ydj1-151 mutant cells, this chaperone is associated with the short-lived substrate Ub-P-beta-gal and not with stable beta-gal constructs. Furthermore, in the ydj1-151 mutant, the ubiquitination of Ub-P-beta-gal was blocked and the total level of ubiquitinated protein in the cell was reduced. Thus, Ydj1 is essential for the ubiquitin-dependent degradation of certain proteins. This chaperone may facilitate the recognition of unfolded proteins or serve as a cofactor for certain ubiquitin-ligating enzymes.     

Medical ethics and truth telling in the case of androgen insensitivity syndrome.

Should a physician always tell the truth to a patient? Is biomedical ethics too "politically correct" in certain situations? The second-place winner in the 1995 Logie Medical Ethics Essay Contest discusses whether telling the truth is the proper course for a physician dealing with certain patients.     

A stochastic dynamical model for the characterization of the geometrical structure of dendritic processes

Under certain basic assumptions the branching pattern of dendrites can be modeled as a Galton-Watson process in varying environment. Using results from graph theory we compute the probability distributions, expectations and variances for biologically significant variables such as the number of (intermediate and terminal) branches, the maximum number of orders, etc., together with the limit behavior of these quantities. Furthermore, the probability measure induced by the Galton-Watson process on the set of all trees is calculated. The measure assigns to any set of branching patterns the probability that it is realized by a certain process, which is completely described through the bifurcation probabilities.     

Do different populations of GABA-receptors exist in the vertebrate CNS?

Studies of the possible multiplicity of GABA-receptors that have been conducted with ligand-binding techniques and with certain electrophysiological and behavioral methods have been reviewed and analyzed. It seems evident that different populations of GABA binding sites exist in subcellular preparations of CNS tissues, but it is not yet certain that these sites reflect different populations of GABA-receptors that might exist in vivo.     

A theory for the chemical mediation of the excitability of the brain, with special reference to natural and drug-induced sleep.

We review evidence which suggests to us that uracil, or a molecule structurally resembling uracil, is likely to be involved in the mediation of level of arousal. In addition we attempt to show that at least one theory, based on this idea, provides a molecular mechanism for certain features of natural sleep, and for the effect on arousal of several classes of drugs and of certain gene mutations. This theory, and related ones, can feasibly be tested further with existing methods.