Lesions transient

Regeneration processes, such as substitution of denaturated enzymes by enzyme synthesis and mechanisms for the repair of DNA, can sometimes render the effect of the chemical lesion transient. On the other hand, taking into account the essentially irreversible character of chemical lesions, there is a tendency for the effect to be cumulative. This accumulation is one of the main factors in the long-term toxicity of cancerogenic and mutagenic agents. 

Mild pain with transient burning/ Apply to all lesions q3h stinging, pruritus, rash, vulvitis, 6 times daily for 1 wk edema or pain at application site Irritation at application site, Apply q2h for 4 d... 

Sallanon, M., Sakai, K, Denoyer, M., Jouvet, M. (1989) Long lasting insomnia induced by preoptic neuron lesions and its transient reversal by muscimol injections into the posterior hypothalamus. Neuroscience. 32, 669-83. 

The majority of patients treated for primary and secondary syphilis experience the Jarisch-Herxheimer reaction after treatment, characterized by flu-like symptoms such as transient headache, fever, chills, malaise, arthralgia, myalgia, tachypnea, peripheral vasodilation, and aggravation of syphilitic lesions. 

In rats, the administration of fullerene by inhalation, as nano- and microparticles generated by aerosol, does not lead to lesions and only a little increase of protein concentration in bronchoalveolar lavage fluid was obtained (Baker et al., 2007). Recently, Sayes et al. (2007) analyzed in vivo pulmonary toxicity of C60 and C60(OH)24, after intratracheal instillation in rats. They verified only transient inflammatory and cell injury effects, 1 day postexposure, without differences from water-instilled controls. No adverse lung tissue effects were measured, and the results demonstrated little or no differences in lung toxicity effects between the C60 and fiillerols, compared to controls. 

Areas related to the evaluation of the adversity of an effect are reversibility and irreversibility and adaptation to an exposure. Irreversible effects are always of great concern. Reversible effects may also be of great concern depending on the nature of the effect and on the setting in which they occur. It cannot be mled out that a permanent lesion may have occurred even if the overt effect is transient. Eurthermore, when there is a more or less continuous exposure to a substance, the question of reversibility is not relevant because adaptation systems will be counteracted by new insults. In many cases it is not possible to draw any conclusion on whether an effect is reversible or not as such experimental data are rare, and all significant health effects that can impair function, both reversible and irreversible, should therefore be considered in the hazard assessment. 

Toxicology. Tantalum has a low order of toxicity but has produced transient inflammatory lesions in the lungs of animals. 

Liver Methotrexate causes hepatotoxicity, fibrosis, and cirrhosis, but generally only after prolonged use. Acutely, liver enzyme elevations are frequent, usually transient and asymptomatic, and also do not appear predictive of subsequent hepatic disease. Liver biopsy after sustained use often shows histologic changes, and fibrosis and cirrhosis have occurred these latter lesions often are not preceded by symptoms or abnormal liver function tests (see Precautions). For this reason, periodic liver biopsies are usually recommended for psoriatic patients who are under long-term treatment. Persistent abnormalities in liver function tests may precede appearance of fibrosis or cirrhosis in the RA population. 

A similar pattern of reactivity has been observed by Burrows and coworkers for the reaction between A -acetyllysine methyl ester (Lys) and dG. This reaction was studied in order to gain an understanding of structural aspects of DNA-protein cross-links (DPCs). These cross-links are regarded as a common lesion of oxidative damage to cells, but remain, from a chemical point, a poorly understood DNA lesion. As pointed out by Burrows, oxidation of protein-DNA complexes should occur preferentially at the primary amines since these sites have a lower oxidation potential (1.1 V vs. NHE, pH 10) than G. While protonation of the primary amine inhibits the oxidative process, transient deprotonation of a lysine residue would give rise to a lysine aminyl radical (or aminium radical cation). Using... 

Management has three important caveats. Firstly, it is mandatory that the causative lesion be reliably identified and, if possible, corrected. Here it should be remembered that a suboptimal intake of this vitamin is frequently seen in those who have diets deficient in vegetables and particularly fresh leafy products found in salads. Secondly, once treatment is initiated, there may be precipitous falls in serum potassium as ineffective haematopoiesis suddenly corrects and so removes the substantial delivery of the intracellular cation to the circulation renal compensation requires slightly longer to adapt and in that interval cardiac arrhythmia and death can occur. Eor this reason patients either need to have plasma electrolytes monitored initially or arbitrary oral potassium replacement supplied. Thirdly, there may be a transient increase in haemoglobin, which then reaches a plateau, and this is the consequence of exhausting available iron stores so that monitoring is necessary or supplementation with simple ferrous salts provided. 

The concept of toxicity is an important one it involves a damaging, noxious, or deleterious effect on the whole or part of a living system, which may or may not be reversible. The toxic response may be a transient biochemical or pharmacological change or a permanent pathological lesion. The effect of a toxic substance on an organism may be immediate, as with a pharmacodynamic response such as a hypotensive effect, or delayed, as in the development of a tumor. 

The most important adverse effect of capsaicin is the initial burning sensation that it produces. Intravesical capsaicin induces intense suprapubic pain during intravesical instillation that may be made tolerable by lidocaine in some but not all patients. Capsaicin also frequently causes a transient worsening of the urinary conditions before improvement of symptoms due to desensitization of bladder afferents becoming evident. In patients with high spinal cord lesions capsaicin might provoke life-threatening autonomic dysreflexia. 

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