Christine A. Davies

The Progression and Topographic Distribution of Interleukin-1β Expression after Permanent Middle Cerebral Artery Occlusion in the Rat

The cytokine interleukin-1 (IL-1) has been implicated in the exacerbation of ischemic damage in the brains of rodents. This study has ascertained the cellular localization and chronologic and topographic distribution of pro/mature interleukin-1β (IL-1β) protein 0.5, 1, 2, 6, 24, and 48 hours after ischemia by subjecting rats to permanent unilateral occlusion of the middle cerebral artery. Interleukin-1β was localized immunocytochemically in vibratome sections of perfusion-fixed brains. The cells that expressed IL-1β had the morphologic features of microglia and macrophages. Interleukin-1β was first detected 1 hour after occlusion in ipsilateral meningeal macrophage-like cells. By 6 hours, pro/mature IL-1β-immunoreactive (IL-1βir) putative microglia were present in the ischemic cerebral cortex, corpus callosum, caudoputamen, and surrounding tissue. By 24 and 48 hours after ischemia, the number and spread of IL-1βir cells increased greatly, including those resembling activated microglia and macrophages, as the core of the infarct became infiltrated. Interleukin-1βir cells also were present in apparently undamaged tissue, adjacent to the lesion ipsilaterally, and contralaterally in the cerebral cortex, dorsal corpus callosum, dorsal caudoputamen, and hippocampus. These results support the functional role of IL-1 in ischemic brain damage and reveal a distinct temporal and spatial expression of IL-1β protein in cells believed to be microglia and macrophages.

An integrated analysis of the progression of cell responses induced by permanent focal middle cerebral artery occlusion in the rat

Defining the chronology and severity of cell damage in an evolving lesion after ischemia is important for understanding the underlying mechanisms in the development of therapeutic intervention. In the present study, we used a combination of histological and immunocytochemical methods to evaluate cell responses from 30 min to 48 h after permanent occlusion of the middle cerebral artery (MCAO) in the rat. Specific immunocytochemical markers clearly revealed acute early responses in neurons (neurofilament protein 200), astrocytes (glial fibrillary acidic protein), and microglia/macrophages (OX-42 and ED-1) such as enlarged, convoluted neuronal processes, and disintegration of glia. Progressive topographic changes in the developing lesion, pinpointed by immunolabeling, indicated the severity and extension of the cell damage. Proliferation and hypertrophy of astrocytes and microglia around the infarct, and contralaterally, occurred 24-48 h after MCAO and coincided with mass necrosis and infiltration of neutrophils and macrophages into the core. These observations corroborate the suggestion that the inflammatory process is involved in the progression of the infarct.

Effects of differential environments on the cerebral anatomy of rats as a function of previous and subsequent housing conditions

After 1 month in enriched or impoverished environments, groups of rats were housed for an additional month in either the same or the opposite environment. The cross-over design allowed us to see whether or not the cerebral effects of differential environments are modified by subsequent housing conditions, and also whether or not such effects might be influenced by previous experience. Differential housing for 1 month was associated with significant alterations in the weight and length of the cerebrum, the thickness of the occipital cortex, and the relative number of neurons and oligodendrocytes, and no change in the ratio of astrocytes to neurons. The effects of enrichment were not reduced in animals that were previously impoverished. When impoverishment followed enrichment, certain effects appeared to diminish, notably, the increase in cortical thickness. Other effects, however, such as the increase in the ratio of oligodendrocytes to neurons, were very stable. The gross cerebral alterations associated with differential housing did not differ significantly after 2 as opposed to 1 months exposure, but the effects on neuronal density and the ratio of oligodendrocytes to neurons in layers V and VI of the cortex were, paradoxically, significantly smaller with the longer duration. We suggest that this decrease is due to the continuation of processes induced in the first month of differential experience rather than to their dissipation.

Deficits in synapse-to-neuron ratio due to early undernutrition show evidence of catch-up in later life

30-day-old rats undernourished from birth are known to have large deficits in the synapse-to-neuron ratio in certain brain regions. It has not been possible to demonstrate any statistically significant deficits in this ratio in animals undernourished from birth to 30 days but then provided with an ad libitum amount of food till 6 months of age.

The effects of early-life undernutrition and subsequent environment on morphological parameters of the rat brain

The investigation examines the extent to which lasting effects of early-life undernutrition on the brain of rats can be modified by manipulating the amount of environmental stimulation later. Infant rats were undernourished during the vulnerable brain growth spurt in the lactation period; then after two months of unrestricted feeding, they were placed in enriched or impoverished environments. Measurements of the forebrain, posterior cerebral cortex and hippocampus showed that neither undernutrition nor environmental stimulation affected the brain uniformly and that some parameters were more susceptible to one condition than the other. Where nutritional and environmental conditions affected the same anatomical dimensions, their combined effects appeared to be additive rather than synergistic.

Expression of advanced glycation end products and their receptor in skin from patients with systemic sclerosis with and without calcinosis.

OBJECTIVES Our aim was to establish which tissue components express advanced glycation/lipoperoxidation end products (AGEs) and their receptor (RAGE) in skin from patients with SSc, and how their expression relates to the disease subtypes and various clinical parameters. METHODS Skin punch biopsies were taken from the forearms of 61 SSc patients with lcSSc; 32 with calcinosis (lcSScCal) and 29 without lcSSc, 36 with the dcSSc subtype and 22 healthy control subjects. Immunohistochemical localization of AGE-CML [N(epsilon)-(carboxymethyl) lysine] and RAGE was assessed semi-quantitatively on the microvascular endothelium, dermal fibroblasts and the cutaneous extracellular matrix (ECM). The Kruskal-Wallis one-way ANOVA was used to compare data between groups. RESULTS AGE-CML expression on the papillary dermis ECM of lcSScCal was greater than in the control group (P = 0.016). The reticular dermis of lcSScCal showed increased AGE-N(epsilon)-(carboxymethyl) lysine (CML) expression compared with controls (P = 0.002), dcSSc (P = 0.024) and lcSSc (P = 0.025). Increased immunostaining for RAGE was seen on the reticular dermis ECM of the lcSScCal group compared with controls (P = 0.007). The lcSScCal subgroup showed statistically significant correlations for AGE-CML, and to a lesser extent for RAGE, with increased RP duration. There was no consistent evidence that the expression of AGE-CML or RAGE related to autoantibody status, clinical or histological skin score or patient age. CONCLUSIONS Our results indicate the possible contribution of AGE-CML deposition on the ECM in the dermis of the lcSScCal subgroup to the pathogenesis of formation of calcinotic deposits.