One-year study of spatial memory performance, brain morphology, and cholinergic markers after moderate controlled cortical impact in rats

Persistent cognitive deficits are one of the most important sequelae of head injury in humans. In an effort to model some of the structural and neuropharmacological changes that occur in chronic postinjury brains, we examined the longitudinal effects of moderate vertical controlled cortical impact (CCI) on place learning and memory using the Morris water maze (MWM) test, morphology, and vesicular acetylcholine (ACh) transporter (VAChT) and muscarinic receptor subtype 2 (M2) immunohistochemistry. Vertical CCI (left parietal cortex, 4 m/sec, 2.5 mm; n = 10) or craniotomy (sham) was produced in male Sprague-Dawley rats (n = 10). Place learning was tested at 2 weeks, 4 weeks, 3 months, 6 months, and 12 months postinjury with the escape platform in a different maze quadrant for each time point. At each interval, rats received 5 days of water maze acquisition (latency to find hidden platform), a probe trial to measure place memory, and 2 days of visible platform trials to control for nonspecific deficits. At 3 weeks, half the animals were sacrificed for histology. At these injury parameters, CCI produced no significant differences in place learning between injured and sham rats at 2 weeks, 4 weeks, or 6 months after injury. However, at 3 and 12 months, the injured rats took significantly longer to find the hidden platform than the sham rats. Probe trial performance differed only at 12 months postinjury between injured (25.73+/-2.1%, standard error of the mean) and sham rats (44.09+/-7.0%, p < 0.05). The maze deficits at 1 year were not due to a worsening of performance, but may have resulted from a reduced ability of injured rats to benefit from previous water maze experience. Hemispheric loss of 30.4+/-5.5 mm3 was seen at 3 weeks after injury (versus respective sham). However, hemispheric loss almost doubled by 1 year after injury (51.5+/-8.5 mm3, p < 0.05 versus all other groups). Progressive tissue loss was also reflected by a three- to fourfold increase in ipsilateral ventricular volume between 3 weeks and 1 year after injury. At 1 year after injury, immunostaining for VAChT was dramatically increased in all sectors of the hippocampus and cortex after injury. Muscarinic receptor subtype 2 (M2) immunoreactivity was dramatically decreased in the ipsilateral hippocampus. This suggests a compensatory response of cholinergic neurons to increase the efficiency of ACh neurotransmission. Moderate CCI in rats produces subtle MWM performance deficits accompanied by persistent alteration in M2 and VAChT immunohistochemistry and progressive tissue atrophy. The inability of injured rats to benefit from repeated exposures to the MWM may represent a deficit in procedural memory that is independent of changes in hippocampal cholinergic systems.     

105Changes in Nitric Oxide Levels After Deep Dermal injury in the Female,Red Duroc Pig (FRDP)

Introduction : Hypertrophic scar is a devastating sequel to burns and other tangential skin injuries. It follows deep dermal injuries and does not occur after superficial injuries. Nitric oxide (NO) plays many important roles in wound healing from inflammation to scar remodeling. Studies have shown that expression of nitric oxide synthase and nitric oxide production are decreased in human hypertrophic scar. However little is known about NO involvement in the early stages of hypertrophic scarring, because of the lack of an animal model. It was recently reported that the female red Duroc pig (FRDP) makes thick scar, which is similar to human hypertrophic scar. We hypothesized that NO production in wounds on the female, red Duroc pig is similar to that of human hypertrophic scar and that NO involvement in deep wounds is different from that in superficial wounds. Methods : Superficial (0.015” to 0.030”) and deep (0.045” to 0.060”) wounds were created on the backs of four FRDPs. Biopsies were collected at weeks 1.5, 4, 8 and 21 post wounding including samples of uninjured skin. Nitric oxide levels were measured with the Griess reaction assay and normalized with tissue protein level. Results : Superficial wounds healed with an invisible scar whereas the deep wounds healed with scar resembling mild hypertrophic scar. The thickness of the scars from the deep wounds was significantly greater than uninjured skin and healed superficial wounds (p < 0.01). NO levels were increased at 1.5 weeks in deep wounds compared to superficial wounds and uninjured skin (p < 0.05). At 8 weeks, NO levels in deep wounds had returned to the level of uninjured tissue and superficial wounds. By 21 weeks, NO levels had decreased significantly when compared to superficial wounds (p < 0.01). There were no differences in NO levels between uninjured skin and superficial wounds at any time point (p > 0.05). Conclusions : NO production is similar in late, deep wounds on the female, red Duroc pig to that reported in the literature for human hypertrophic scar further validating this animal model. NO production is quite different after deep wounds as compared to superficial wounds in the FRDP. Early elevation in nitric oxide production might account for excessive inflammation in deep wounds that become thick scars in the FRDP. Nitric oxide regulators and effects at early stages of scar formation should be elucidated further and the FRDP appears to be a useful model.     

Subtle lung cancers: impact of edge enhancement and gray scale reversal on detection with digitized chest radiographs

The authors studied the impact of edge enhancement and gray scale polarity reversal on the detection of subtle lung cancers. Three experienced readers reviewed 46 biopsy-proved subtle lung cancers and 46 normal controls on chest radiographs that had been digitized into a 1,024 X 1,536-pixel matrix 8 bits deep. Receiver-operating characteristics (ROC) analysis of 1,656 pooled observations indicated that performance was best with the unmodified images (ROC area = 0.83), degraded by moderate enhancement of medium frequencies (ROC area = 0.80), and markedly impaired by severe enhancement of low frequencies (ROC area = 0.69). Gray scale polarity reversal further degraded performance (unenhanced ROC area = 0.74; moderately enhanced ROC area = 0.76; severely enhanced ROC area = 0.76). The authors conclude that edge enhancement and gray scale polarity reversal can impair the detectability of subtle lung cancers on digitized radiographs of medium resolution.     

Cerebrospinal fluid biomarkers versus glasgow coma scale and glasgow outcome scale in pediatric traumatic brain injury: the role of young age and inflicted injury

The Glasgow Coma Scale (GCS) and Glasgow Outcome Scale (GOS) are widely used clinical scoring systems to measure the severity of neurologic injury after traumatic brain injury (TBI), but have recognized limitations in infants and small children. Cerebrospinal fluid (CSF) concentrations of neuron-specific enolase (NSE) and S100B show promise as markers of brain injury. We hypothesized that the initial GCS and 6-month GOS scores would be inversely associated with CSF NSE and/or S100B concentrations after severe pediatric TBI. Using banked CSF obtained during ongoing studies of pediatric TBI, NSE and S100B were determined in CSF collected within 24 h of trauma from 88 infants and children with severe TBI (GCS < or = 8) versus 20 non-injured controls. Victims of inflicted (iTBI) and non-inflicted TBI (nTBI) showed similar (>10-fold) increases in both NSE and S100B versus control. Both markers showed overall significant, inverse correlation with GCS and GOS scores. In subgroup analysis, both markers correlated significantly with GCS and GOS scores only in older (>4 years) victims of nTBI; no correlation was found for patients < or =4 years old or victims of iTBI. While confirming the overall correlations between GCS/GOS score and CSF NSE and S100B seen in prior studies, we conclude that these clinical and CSF biomarkers of brain injury do not correlate in children < or =4 years of age and/or victims of iTBI. Although further, prospective study is warranted, these findings suggest important limitations in our current ability to assess injury severity in this important population.     

Effect of inducible nitric oxide synthase on cerebral blood flow after experimental traumatic brain injury in mice

Inducible nitric oxide synthase (iNOS) has been suggested to play a complex role in the response to central nervous system insults such as traumatic brain injury (TBI) and cerebral ischemia. In the current study, we quantified maps of regional cerebral blood flow (CBF) using an arterial spin-labeling magnetic resonance imaging (MRI) technique, at 24 and 72 h after experimental TBI in iNOS knockout (KO) and wild-type (WT) mice. Our hypothesis was that iNOS would contribute to the level of CBF at 72 h after experimental TBI in mice. Comparing anatomical brain regions of interest (ROIs) at 24-h post controlled cortical impact (CCI), there were significant reductions in CBF in the hemisphere, cortex, and contusion-rich area of the cortex of injured animals versus naive, regardless of genotype. Regional assessment of CBF at 72 h after injury demonstrated that recovery of CBF was reduced in the ipsilateral hippocampus, thalamus, and amygdala/piriform cortex in iNOS KO versus WT mice by 26%, 15%, and 21%, respectively; this attenuated recovery was restricted to structures outside the contusion. These regions with reduced CBF in iNOS KO mice represented ROIs where CBF in the WT was either numerically or statistically greater than that seen in respective WT naive, suggesting a contribution of iNOS to delayed posttraumatic hyperemia. However, pixel analysis denoted that the contribution of iNOS to CBF at 72 h was not limited to hyperemia flows. In conclusion, iNOS plays a role in the recovery of CBF after CCI in mice. Questions remain if this effect represents a homeostatic component of CBF recovery, pathologic vasodilatation linked to inflammation, or NO-mediated facilitation of angiogenesis.     

Local and transient inhibition of p21 expression ameliorates age‐related delayed wound healing

Nonhealing chronic wounds in the constantly growing elderly population represent a major public health problem with high socioeconomic burden. Yet, the underlying mechanism of age‐related impairment of wound healing remains elusive. Here, we show that the number of dermal cells expressing cyclin‐dependent kinase inhibitor p21 was elevated upon skin injury, particularly in aged population, in both man and mouse. The nuclear expression of p21 in activated wound fibroblasts delayed the onset of the proliferation phase of wound healing in a p53‐independent manner. Further, the local and transient inhibition of p21 expression by in vivo delivered p21‐targeting siRNA ameliorated the delayed wound healing in aged mice. Our results suggest that the increased number of p21⁺ wound fibroblasts enforces the age‐related compromised healing, and targeting p21 creates potential clinical avenues to promote wound healing in aged population.