Primary damage

Primary damage from an explosion may result from several events ... 

In animals the primary damage from intoxication is to the liver, but in humans the majority of fatalities have been due to renal injury with secondary cardiac failure. Human autopsy reports have confirmed renal tubular necrosis. In humans, liver damage occurs more often after ingestion of the liquid than after inhalation of the vapor. 

In genotoxic assays PNCB induced reverse mutations but not primary damage in bacteria. At toxic doses, it induced chromosomal aberrations, sister chromatid exchange, and repairable DNA breaks in cultured mammalian cells. In vivo it induced DNA damage in mice. ... 

Since in both cases the primary damage is set by OH, these differences can be explained if the transition metal ion which must be still near the damaged site modifies the damage prior to a reaction of oxygen. Alternatively, H202 which was present at rather high concentrations in these experiments (0.1 to 0.4 mol... 

MPTP is one example of a toxicant that causes direct structural damage to neurons, resulting in loss of function. In the following sections, other types of structural and functional effects of neurotoxicants are described. Structural effects are divided into three primary types effects on myelin formation, primary damage to axons, and direct promotion of cell death. Neurons may also be secondarily affected by neurotoxicants... 

Neuronopathy. Neuronopathy refers to generalized damage to nerve cells, with the primary damage occurring at the nerve cell body. Axonal and dendritic processes die secondarily in response to loss of the cell body. Like other cells in the body, neurons die by one of two processes distinguished by their morphological and molecular features apoptosis and necrosis. (This division is overly simplistic there is much debate... 

Materials Degradation Effects. Virtually all of the effects of S02 on materials are associated with its dissolution in surface moisture as the primary mechanism of deposition (19). Thus an appropriate environmental index for materials damage should include not only the average ambient S02 concentration but also a measure of the portion of time that the material surfaces are wet and thus receptive to S02 deposition. Sulfur in the atmosphere has an additional adverse affect on some materials through acidification of precipitation however, for both "dry" deposition of S02 and impact by acid precipitation, the primary damage mode is attack by dilute acids. 

The SN often associated with the Hu antibody is characterized by primary damage to the nerve cell body. The patient suffers from progressive, painful sensory disturbances evolving subacutely, usually with a Rankin score of 3 within 12 weeks of the onset of symptoms [14]. Presenting symptoms include paresthesia, hypoestesia, and very often proprioceptive loss in the affected areas sensory ataxia is common. The upper limbs are often involved [97], The distribution of the SN is often atypical for peripheral neuropathy. The involvement is usually asymmetrical, especially at the onset of symptoms, and may affect the face or upper limbs only. SN is often the presenting symptom of the PEM/SN syndrome, but signs of CNS involvement usually evolve, and autonomic disturbances are common [36]. 

An alternate method of classification of damage mechanisms in terms of environmental conditions such as stress, temperature, corrosion, wear, radiation is known as the failure wheel. In this representation secondary mechanisms are underlined as opposed to primary damage mechanisms. The boiler tube failure discussed can be represented in terms of failure wheel, as shown in Figure 2.31. The aim in any case is to identify definitively the underlying mechanism of failure to enable one to undertake remedial action such that future failures do not occur. 

Figure 50.4 depicts the basic chemical mechanism by which sulfur mustard incurs the primary damage to biological molecules which results in subsequent damage to cells, tissues, and organs. 

DNA primary damage DNA single and double strand-breaks, alkali-labile sites, incomplete excision repair sites, DNA-DNA and DNA-protein crosslinks. 

DNA primary damage DNA adducts (alkyl and bulky adducts) are nucleotide bases covalently modified by reactive electrophilic chemical intermediates or free radicals. 

Repair of DNA lesions and unscheduled DNA synthesis in response to DNA primary damage. 

Venous (red) thrombi develop in areas of slow blood flow (e.g., leg veins of a bedridden patient). The clot forms rapidly and lacks the organization of the arterial thrombus. Venous occlusion occurs, but is not the primary damage caused by venous thrombi. More worrisome is the tendency of small pieces (emboli) to detach from venous thrombi and travel to pulmonary arteries. The emboh wedge into pulmonary arteries, prohibiting deoxygenated blood from entering the portion of the limg served by the embolized artery. 

For 19 of the 38 pesticides tested in the bioassays (grouped in Tables lll-VI), a mutagenic or related effect was found. Of the 19, however, 11 were positive for primary damage to DNA only. 

Abrasive wear takes place when two hard materials are brought into contact without bonding, when the primary damage is associated with mechanical interlocking (shear of asperities) and the generation of Herzian cone-cracks surrounding the contact points [115, 116],... 

It was earlier reported that photoinhibition in intact thylakoid membranes is a multistep event and that inhibition of electron transport is followed by a slow degradation of the reaction center proteins D1 and D2 (3). From the spectroscopic data presented above we conclude that the primary damage to the reaction center proteins is caused by the primary charge separation or donor side reactions in centers were the function of ( A has been impair. To further test the hypothesis that the protein degradation is initiated by reactions on the oxidizing side of PSII, we... 

Eliminates delamination, which is the primary damage mechanism in laminated composites Reduced cost Better performance... 

---