Chemical exposure during embryonic development may cause persistent effects, yet developmental toxicity data exist for very few chemicals.
Gram-negative coliform bacteria acquired from the environment, such as Klebsiella (K). pneumoniae, frequently cause an acute inflammatory response with severe clinical signs, while Gram-positive contagious pathogens such as Staphylococcus (S). aureus may cause persistent, subclinical and chronic infections.
The secondary and tertiary phases may cause persistent inflammation and gliosis, sensitization to further injury, and impaired oligodendrocyte maturation and myelination [19].
Despite migraine is not the most disabling disturbance of CADASIL, it may cause persistent discomfort to patients, especially in those with frequent attacks, and may lead to hospitalization, especially because some auras are difficult to differentiate from cerebrovascular events in these patients.
Chronic exposure to relatively low levels of carbon monoxide may cause persistent headaches, lightheadedness, depression, confusion, memory loss, nausea and vomiting.
Our hypothesis is that an early and strong Th1-response, besides providing an effective eradication, which is important in order to avoid dissemination before antibiotic treatment, is a prerequisite for a proper down regulation of the inflammation, thus avoiding low grade chronic inflammation that may cause persistent symptoms despite absence of the spirochetes.
Other insults such as chronic exposure to pro-inflammatory cytokines, which are elevated in the plasma and brain tissue of pre-symptomatic HD patients, may also cause persistent activation of IKKβ in neurons and further exacerbate the cleavage of Htt [19], [22].
Chronic transudation of interstitial edema of a large tumor may cause the persistent retention of ascites [10].
VSV infection in neurons may lead to immediate morbidity or even mortality in humans, or it may cause a persistent non-lethal infection as seen in other mammals, presenting as sores on the feet or mucus membranes of the mouth and nose [52], [53].
As volume can decline because of changes in cell number, synaptic number or density, or other changes in cellular architecture, these findings reinforce evidence that lead may cause a persistent change in the brain that is associated with progressive declines in cognitive function.
Attributes of the parasite may also account for the propensity to cause persistent diarrhea in children in developing countries.
