Beta-effect

The clinical effects following overdose depend on the receptor selectivity (alpha and/or beta effect). Most patients require only observation for a period of 4-8 h. Pharmacologic intervention is required only in severely symptomatic patients (cardiac arrhythmias, hypertensive crisis, seizures, hyperthermia). Severe overdose effects may most commonly result in hypertension, tachycardias, followed by bradycardia, and arrhythmias, seizures, cerebral hemorrhages and ischemia or vasoconstriction, psychosis, and hyperthermia. 

The stabilisation of carbon cations by a (3-C-Si bond (the beta effect ) was the first carbon-metal hyperconjugation to be recognised, and provided the basis for extending the concept further down Group 14. The most direct evidence for hyperconjugation, however, comes from the ESR spectroscopy of radicals. 

M.A. Camblor and J. Perez-pariente, Crystallization of Zeolite Beta - Effect of Na and K-Ions. Zeolites, 1991, 11, 202-210. 

Camblor, M. A. and Perez-Pariente, J. 1991. Crystallization of zeolite Beta Effect of Na and K ions. Zeolites 11 202-210. 

Net cardiovascular actions Sympathomimetics with both alpha and beta, effects (eg, norepinephrine) may cause a reflex increase in vagal outflow because they increase blood pressure and evoke the baroreceptor reflex. This reflex bradycardia often dominates any direct beta effects on the heart rate, so that a slow infusion of norepinephrine typically causes increased blood pressure and bradycardia (Figure 9-2). If the reflex is blocked (eg. by a ganglion blocker), norepinephrine may cause a direct beta,-mediated tachycardia. A pure... 

Figure 9-2. Typical effects of the principal catecholamines on blood pressure and heart rate. Note that the pulse pressure ( Pulse ) is only slightly increased by norepinephrine but is markedly increased by epinephrine and isoproterenol. The reduction in heart rate caused by norepinephrine is the result of baroreceptor reflex activation of vagal outflow to the heart. The blood pressure effects of epinephrine are typically dose-dependent small doses exhibit more beta effect (isoproterenol-like) large doses exhibit more alpha effect (norepinephrine-like).

The 10 beta effect of mercury is larger than that of silicon and comparable to that of germanium. Interestingly, hyperconjugative assistance with mercnry increases with the nucleophilicity of the solvent, suggesting that coordination of solvent with mercnry in the transition state increases polarizability and nucleophilicity of... 

Lambert, J. B., Emblidge, R. W. (1993). Nucleophilic catalysis in deoxymercuration the beta effect of mercury. Journal of Physical Organic Chemistry, 6,555—560. 

The BERENICE programme (Beta Effective JReactor Experiment for a New international Collaboration Evaluation) has been carried out at the MASURCA critical facility (CE CADARACHE) with the participation of an european team (UK (AEA-T), Italy (ENEA) and France (CEA)) and teams from Japan, (JAERI), USA (LANL) and Russia (IPPE). 

This difference produces a longer period for a given addition of reactivity which can be seen in the reactor period equation, T - ( -p)/Xp. With beta effective used instead of beta, the term (Peff P larger giving a longer period. 

In man the beta-blockade inhibits the circulatory beta effects of adrenaline but not the kininoge-nolysis the opposite happens in rabbit. 

Grimaud E, Heymann D, Redini F. Recent advances in TGF-beta effects on chondrocyte metabolism. Potential therapeutic roles of TGF-beta in cartilage disorders. Cytokine Growth Factor Rev. 2002 13(3) 241-257. 

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