Hormone theory

Czajlachian, M.C., Hormonal-theorie der Entwicklung der Pflanzen, Verl. Akad. d. Wissensch. Moskau u. Leningrad, 200S, 1937. 

The so-called hormone theory (X Ahlqvist, 1980) is based on the impact of hyperoestrogenaemia on the biliary/canalicular system and bile acid metabolism. The question of sequential causality remains open. (quot. 75)... 

Deficiency in essential fatty acids (e.g., omega-3 fatty acids) may cause a dysregulation of neurotransmitter activity. Neurotransmitter/neuroendocrine/hormonal theories... 

Lastly our work proves that EDKINS pyloric hormone theory is utterly inadequate that... 

Comparative studies of transport in Phaseolus vulgaris. New Phytol 62 173-197 Loeb J (1917) Influence of leaf upon root formation and geo tropic curvature in the stem of Bryophyllum calycinum and the possibility of a hormone theory of these processes. Bot Gaz 63 25-50... 

By the turn of the century the theory of chemical mediation of physiologic responses had gained some currency. There ensued in some laboratories an intense search for endogenous chemical modifiers of bodily responses. The first such agent to be isolated from mammalian tissue was the ubiquitous hormone, epinephrine—at that time known as adrenaline. This compound has played an important role in pharmacology as well as in medicinal chemistry. 

Since the theory and medical applications of collagen sponge were described by Chvapil et al. (52-54), they have been used to deliver steroid hormones (55), the anticancer drugs trans-retinoic acid (TRA) (56,57), and 5-fluorouracil (5-FU) (58), and antibiotics (59). 

First described in 1926 by Perrin [16], the theory was greatly expanded by Weber [17], who developed the first instrumentation for the measurement of FP. Dandliker [18] expanded FP into biological systems such as antigen-antibody reactions and hormone-receptor interactions. Jolley [19] developed FP into a commercial system for monitoring of therapeutic drug levels and the detection of drugs of abuse in human body fluids. 

Many women seek medical treatment for the relief of menopausal symptoms, primarily hot flashes however, the role of hormone-replacement therapy (HRT) has changed dramatically over the years. HRT has long been prescribed for relief of menopausal symptoms and, until recent years, has been purported to protect women from CHD. The original reason behind recommending HRT in postmenopausal women revolved around a simple theory If the hormones lost during menopause were replaced through drug therapy, women would be protected from both menopausal symptoms and chronic diseases that often follow after a woman experiences menopause. Recent studies have disproved this theory. 

Although there has been a substantial body of pharmacological evidence in support of the monoamine theory of depression, clinical biochemical data have been less convincing (Luchins, 1976) this is where differences in the concentrations of NA and 5-HT and their metabolites or hormones, which are ultimately under the control of brain monoaminergic neurons (neuroendocrine markers), have been compared between depressed patients and normal controls. However, by the early 1970s a major difficulty with the theory was becoming apparent this was the time lag between the immediate... 

Reductionist theories of human behavior are hardly new. During much of the Nineteenth and Twentieth centuries man has been constructed as an evolutionary product, the brain as biochemical, and the body as hormones or genes. The Nineteenth century sciences of craniometry and phrenology reduced social, moral, and intellectual differences to physical manifestations. 

The intracellular distribution of steroid hormone receptors has long been the object of controversy. The first theoretical formulation on the intracellular location of the ERs was elaborated by Jensen in 1968 and is known as the two-step theory. Its execution was based entirely on biochemical observations obtained by means of tritium-marked estradiol. The ERs, in cells not exposed to hormones, are found abundantly in the soluble cell fraction, or cytosol (Fig. 1.1). Treatment with hormones confines the receptors to the particulated or nuclear fraction and causes their disappearance from the cytosol. The two-step theory established that the receptor is found in the cytoplasm naturally and upon the arrival of a hormone it is transformed into a complex hormone-receptor (first step) capable of translocating itself to the nucleus and of modifying gene expression (second step). 

At present, the two-step theory is still accepted, but it leaves out the question of receptor location within the cell so as to be able to cover all members of a family. The receptor, in the absence of hormone, is found associated with other proteins (hsp90, p59, and perhaps others) and very weakly bound to cell structures (nuclear or cytoplasmatic). The arrival of hormones transforms the receptor, freeing it from other proteins, giving it a greater affinity for nuclear structures, and causing it to achieve an active state as a transcription factor (Beato et al. 1996 Beato 1989). The difference is that the receptors not... 

It is obvious why the spectroscopist wants to investigate the structure of integral membrane proteins or enzymes, whose biological action is linked to the presence of phospholipids such as phospholipase, in a membrane-mimicking environment Why such an environment should also be used for other peptides like hormones becomes more clear when we take into account the membrane compartment theory [10-12] as postulated by R. Schwyzer. This theory states that peptides that target membrane-embedded receptors... 

The classical theory of electrophoretic migration has also been successfully applied to the description of the behaviour of human growth hormone peptides. According to the classical theory, the mobility (ju) of a peptide can be described by... 

Bimolecular processes are very common in biological systems. The binding of a hormone to a receptor is a bimolecular reaction, as is substrate and inhibitor binding to an enzyme. The term bimolecular mechanism applies to those reactions having a rate-limiting step that is bimolecular. See Chemical Kinetics Molecularity Reaction Order Elementary Reaction Transition-State Theory... 

Polar Cell Systems for Membrane Transport Studies Direct current electrical measurement in epithelia steady-state and transient analysis, 171, 607 impedance analysis in tight epithelia, 171, 628 electrical impedance analysis of leaky epithelia theory, techniques, and leak artifact problems, 171, 642 patch-clamp experiments in epithelia activation by hormones or neurotransmitters, 171, 663 ionic permeation mechanisms in epithelia biionic potentials, dilution potentials, conductances, and streaming potentials, 171, 678 use of ionophores in epithelia characterizing membrane properties, 171, 715 cultures as epithelial models porous-bottom culture dishes for studying transport and differentiation, 171, 736 volume regulation in epithelia experimental approaches, 171, 744 scanning electrode localization of transport pathways in epithelial tissues, 171, 792. 

Both unimolecular and bimolecular reactions are common throughout chemistry and biochemistry. Binding of a hormone to a reactor is a bimolecular process as is a substrate binding to an enzyme. Radioactive decay is often used as an example of a unimolecular reaction. However, this is a nuclear reaction rather than a chemical reaction. Examples of chemical unimolecular reactions would include isomerizations, decompositions, and dis-associations. See also Chemical Kinetics Elementary Reaction Unimolecular Bimolecular Transition-State Theory Elementary Reaction... 

Current theories suggest that hypersecretion of cortisol during stress may damage the hippocampus. Studies have demonstrated reduced hippocampal volume in trauma survivors with PTSD, compared to nontrauma tized individuals (Sapolsky, 2000 Bremner, 2001). However, hormonally regulated plasticity in the hippocampus involves multiple influences, and glucocorticoid hormones work in concert with excitatory amino acids and N-methyl-D-aspartate (NMDA) receptors, as well as other neurotransmitters and the GABA-benzodiazepine system (see McEwen, 2000a,b, for review). 

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