Cascade Of Morphological Changes Research Articles

Peculiarities of the clinical course of frederick's syndrome on the background of comorbid pathology in the absence of adequate therapy

Atrial fibrillation in old people is one of the most common causes of cardiac decompensation. It can also lead to sudden cardiac death and thromboembolism of vital organs. Comorbidities such as diffuse cardiosclerosis, myocarditis or cardiomyopathy, congenital or acquired defects of the valvular apparatus of the heart, pathology of the endocrine system, chronic obstructive diseases of the bronchopulmonary apparatus, malignant course of arterial hypertension or its refractoriness to therapy, uncontrolled intake of antiarrhythmic drugs, can complicate the course of atrial fibrillation the addition of a transverse atrioventricular block, which is called Frederick’s syndrome. This article presents a case of clinical observation of an uncontrolled course of atrial fibrillation with the subsequent development and progression of severe circulatory failure against the background of the addition of complete atrioventricular block. Such an important factor as adherence to medical recommendations can compensate for various pathological conditions for a long time without causing significant harm to health, which was neglected by the patient from the clinical case under consideration. The launched course of arterial hypertension probably launched a cascade of morphological changes in the structures of the heart, which subsequently led to the formation of atrial fibrillation, the development of heart failure, and the addition of complete atrioventricular block. The appearance of rhythm in the heart rate, which is characteristic of this conduction disturbance, is often perceived as an erroneous restoration of the rhythm in case of pre-existing atrial fibrillation; this can complicate the timely diagnosis of pathology, especially in the absence of syncope conditions characteristic of complete atrioventricular blockade. The risks of thromboembolic complications and sudden cardiac death are as high as those associated with isolated atrial fibrillation. During the examination of the patient, the absolute indications for transplantation of an artificial pacemaker were determined. Subsequently, an increase in the minute volume of blood and cardiac output, as expected, led to an improvement in the clinical course of the disease and well-being, however, the pre-existing hemodynamic disorder of a long-term nature in this patient led to irreversible decompensation of cardiac activity, which adversely affects the long-term prognosis for life.

Global Gene Expression Analysis during Germination in the Chytridiomycete Blastocladiella emersonii

Blastocladiella emersonii is an aquatic fungus of the Chytridiomycete class. During germination, the zoospore, a motile nongrowing cell, goes through a cascade of morphological changes that culminates with its differentiation into the germling cell, capable of coenocytic vegetative growth. Transcriptome analyses of B. emersonii cells were carried out during germination induced under various environmental conditions. Microarray data analyzing 3,563 distinct B. emersonii genes revealed that 26% of them are differentially expressed during germination in nutrient medium at at least one of the time points investigated. Over 500 genes are upregulated during the time course of germination under those conditions, most being related to cell growth, including genes involved in protein biosynthesis, DNA transcription, energetic metabolism, carbohydrate and oligopeptide transport, and cell cycle control. On the other hand, several transcripts stored in the zoospores are downregulated during germination in nutrient medium, such as genes involved in signal transduction, amino acid transport, and chromosome organization. In addition, germination induced in the presence of nutrients was compared with that triggered either by adenine or potassium ions in inorganic salt solution. Several genes involved in cell growth, induced during germination in nutrient medium, do not show increased expression when B. emersonii zoospores germinate in inorganic solution, suggesting that nutrients exert a positive effect on gene transcription. The transcriptome data also revealed that most genes involved in cell signaling show the same expression pattern irrespective of the initial germination stimulus.

Sex Determination and Gonadal Development in Mammals

Arguably the most defining moment in our lives is fertilization, the point at which we inherit either an X or a Y chromosome from our father. The profoundly different journeys of male and female life are thus decided by a genetic coin toss. These differences begin to unfold during fetal development, when the Y-chromosomal Sry ("sex-determining region Y") gene is activated in males and acts as a switch that diverts the fate of the undifferentiated gonadal primordia, the genital ridges, towards testis development. This sex-determining event sets in train a cascade of morphological changes, gene regulation, and molecular interactions that directs the differentiation of male characteristics. If this does not occur, alternative molecular cascades and cellular events drive the genital ridges toward ovary development. Once testis or ovary differentiation has occurred, our sexual fate is further sealed through the action of sex-specific gonadal hormones. We review here the molecular and cellular events (differentiation, migration, proliferation, and communication) that distinguish testis and ovary during fetal development, and the changes in gene regulation that underpin these two alternate pathways. The growing body of knowledge relating to testis development, and the beginnings of a picture of ovary development, together illustrate the complex mechanisms by which these organ systems develop, inform the etiology, diagnosis, and management of disorders of sexual development, and help define what it is to be male or female.

Bordetella adenylate cyclase toxin induces a cascade of morphological changes of sheep erythrocytes and localizes into clusters in erythrocyte membranes

Adenylate cyclase toxin (CyaA) of Bordetella pertussis penetrates the membrane of eukaryotic cells, producing high levels of intracellular cAMP, as well as hemolysis that results from the formation of cation-selective toxin channels in the membrane. Using several microscopical approaches we studied the effects of CyaA action on the morphology of sheep erythrocytes during early phases preceding lysis and examined localization of CyaA molecules within the erythrocyte membrane. CyaA induced a cascade of morphological changes of erythrocytes, such as shrinkage, formation of membrane projections, and blebs and swelling. The use of an enzymatically inactive CyaA-AC- toxoid that is unable to produce cAMP and of a CyaA-E581K mutant exhibiting higher hemolytic activity than with CyaA showed that the hemolytic activity is responsible for the induction of morphological changes of erythrocytes. Further, immunolabeling of inserted CyaA-232/FLAG molecules with specific anti-FLAG antibodies and IgG-gold particles indicated a clustered distribution of CyaA molecules in erythrocyte membrane. This was confirmed by immunofluorescence and confocal microscopy, which revealed uniform stoichiometry of CyaA clusters, suggesting CyaA binding into specific domains in erythrocyte membrane. Indeed, a decrease of CyaA binding after cholesterol depletion of erythrocytes suggests toxin targeting and binding to membrane microdomains (rafts).

Ecdysone-inducible gene expression in mammalian cells and transgenic mice.

During metamorphosis of Drosophila melanogaster, a cascade of morphological changes is triggered by the steroid hormone 20-OH ecdysone via the ecdysone receptor, a member of the nuclear receptor superfamily. In this report, we have transferred insect hormone responsiveness to mammalian cells by the stable expression of a modified ecdysone receptor that regulates an optimized ecdysone responsive promoter. Inductions reaching 4 orders of magnitude have been achieved upon treatment with hormone. Transgenic mice expressing the modified ecdysone receptor can activate an integrated ecdysone responsive promoter upon administration of hormone. A comparison of tetracycline-based and ecdysone-based inducible systems reveals the ecdysone regulatory system exhibits lower basal activity and higher inducibility. Since ecdysone administration has no apparent effect on mammals, its use for regulating genes should be excellent for transient inducible expression of any gene in transgenic mice and for gene therapy.