Immediately after an injury, the nervous system generates "pro-inflammatory" cytokines, which are molecules used to coordinate a response to the insult. These cytokines are toxic to the developing brain, and their activity in an effort to respond to specific areas of damaged tissue is believed to cause "bystander damage" to nearby areas that were not affected by the original insult. Further damage is believed to be caused by free radicals, compounds produced during ischemic episodes. The processes affecting neurons also cause damage to glial cells, leaving nearby neurons with little or no support system. It is thought that other factors might lead to PVL, and researchers are studying other potential pathways. A 2007 article by Miller, et al., provides evidence that white-matter injury is not a condition limited to premature infants: full-term infants with congenital heart diseases also exhibit a "strikingly high incidence of white-matter injury." In a study described by Miller, of 41 full-term newborns with congenital heart disease, 13 infants (32%) exhibited white matter injury. Diagnosis
As previously noted, there are often few signs of white matter injury in newborns. Occasionally, physicians can make the initial observations of extreme stiffness or poor ability to suckle. The preliminary diagnosis of PVL is often made using imaging technologies. In most hospitals, premature infants are examined with ultrasound soon after birth to check for brain damage. Severe white matter injury can be seen with a head ultrasound; however, the low sensitivity of this technology allows for some white matter damage to be missed.
Cultural explorations
During the Renaissance, Edmund Spenser in The Faerie Queene endorsed sadness as a marker of spiritual commitment.In The Lord of the Rings, sadness is distinguished from unhappiness, to exemplify J. R. R. Tolkiens preference for a sad, but settled determination, as opposed to what he saw as the shallower temptations of either despair or hope.Julia Kristeva considered that "a diversification of moods, variety in sadness, refinement in sorrow or mourning are the imprint of a humanity that is surely not triumphant but subtle, ready to fight and creative". See also
Joie de vivre
Melancholia
Mood (psychology)

References


== Further reading ==