Is the Forest Service Keeping Up With the Times?

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75358/1/j.1541-0072.1995.tb01747.x.pd

A new clinico-pathological classification system for mesial temporal sclerosis

We propose a histopathological classification system for hippocampal cell loss in patients suffering from mesial temporal lobe epilepsies (MTLE). One hundred and seventy-eight surgically resected specimens were microscopically examined with respect to neuronal cell loss in hippocampal subfields CA1–CA4 and dentate gyrus. Five distinct patterns were recognized within a consecutive cohort of anatomically well-preserved surgical specimens. The first group comprised hippocampi with neuronal cell densities not significantly different from age matched autopsy controls [no mesial temporal sclerosis (no MTS); n = 34, 19%]. A classical pattern with severe cell loss in CA1 and moderate neuronal loss in all other subfields excluding CA2 was observed in 33 cases (19%), whereas the vast majority of cases showed extensive neuronal cell loss in all hippocampal subfields (n = 94, 53%). Due to considerable similarities of neuronal cell loss patterns and clinical histories, we designated these two groups as MTS type 1a and 1b, respectively. We further distinguished two atypical variants characterized either by severe neuronal loss restricted to sector CA1 (MTS type 2; n = 10, 6%) or to the hilar region (MTS type 3, n = 7, 4%). Correlation with clinical data pointed to an early age of initial precipitating injury (IPI < 3 years) as important predictor of hippocampal pathology, i.e. MTS type 1a and 1b. In MTS type 2, IPIs were documented at a later age (mean 6 years), whereas in MTS type 3 and normal appearing hippocampus (no MTS) the first event appeared beyond the age of 13 and 16 years, respectively. In addition, postsurgical outcome was significantly worse in atypical MTS, especially MTS type 3 with only 28% of patients having seizure relief after 1-year follow-up period, compared to successful seizure control in MTS types 1a and 1b (72 and 73%). Our classification system appears suitable for stratifying the clinically heterogeneous group of MTLE patients also with respect to postsurgical outcome studies

Neutral Bystander, Intrusive Micromanager, or Useful Catalyst?

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73380/1/j.1541-0072.1995.tb01746.x.pd

Does parallel item content on WOMAC's Pain and Function Subscales limit its ability to detect change in functional status?

BACKGROUND: Although the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) is considered the leading outcome measure for patients with osteoarthritis of the lower extremity, recent work has challenged its factorial validity and the physical function subscale's ability to detect valid change when pain and function display different profiles of change. This study examined the etiology of the WOMAC's physical function subscale's limited ability to detect change in the presence of discordant changes for pain and function. We hypothesized that the duplication of some items on the WOMAC's pain and function subscales contributed to this shortcoming. METHODS: Two eight-item physical function scales were abstracted from the WOMAC's 17-item physical function subscale: one contained activities and themes that were duplicated on the pain subscale (SIMILAR-8); the other version avoided overlapping activities (DISSIMILAR-8). Factorial validity of the shortened measures was assessed on 310 patients awaiting hip or knee arthroplasty. The shortened measures' abilities to detect change were examined on a sample of 104 patients following primary hip or knee arthroplasty. The WOMAC and three performance measures that included activity specific pain assessments – 40 m walk test, stair test, and timed-up-and-go test – were administered preoperatively, within 16 days of hip or knee arthroplasty, and at an interval of greater than 20 days following the first post-surgical assessment. Standardized response means were used to quantify change. RESULTS: The SIMILAR-8 did not demonstrate factorial validity; however, the factorial structure of the DISSIMILAR-8 was supported. The time to complete the performance measures more than doubled between the preoperative and first postoperative assessments supporting the theory that lower extremity functional status diminished over this interval. The DISSIMILAR-8 detected this deterioration in functional status; however, no significant change was noted for the SIMILAR-8. The WOMAC pain scale demonstrated a slight reduction in pain and the performance specific pain measures did not reflect a change in pain. All measures showed substantial improvement over the second assessment interval. CONCLUSIONS: These findings support the hypothesis that activity overlap on the pain and function subscales plays a causal role in limiting the WOMAC physical function subscale's ability to detect change

Surface-Enhanced Nitrate Photolysis on Ice

Heterogeneous nitrates photolysis is the trigger for many chemical processes occurring in the polar boundary layer and is widely believed to occur in a quasi-liquid layer (QLL) at the surface of ice. The dipole forbidden character of the electronic transition relevant to boundary layer atmospheric chemistry and the small photolysis/photoproducts quantum yields in ice (and in water) may confer a significant enhancement and interfacial specificity to this important photochemical reaction at the surface of ice. Using amorphous solid water films at cryogenic temperatures as models for the disordered interstitial air/ice interface within the snowpack suppresses the diffusive uptake kinetics thereby prolonging the residence time of nitrate anions at the surface of ice. This approach allows their slow heterogeneous photolysis kinetics to be studied providing the first direct evidence that nitrates adsorbed onto the first molecular layer at the surface of ice are photolyzed more effectively than those dissolved within the bulk. Vibrational spectroscopy allows the ~3-fold enhancement in photolysis rates to be correlated with the nitrates’ distorted intramolecular geometry thereby hinting at the role played by the greater chemical heterogeneity in their solvation environment at the surface of ice than in the bulk. A simple 1D kinetic model suggests 1-that a 3(6)-fold enhancement in photolysis rate for nitrates adsorbed onto the ice surface could increase the photochemical NO[subscript 2] emissions from a 5(8) nm thick photochemically active interfacial layer by 30%(60)%, and 2-that 25%(40%) of the NO[subscript 2] photochemical emissions to the snowpack interstitial air are released from the top-most molecularly thin surface layer on ice. These findings may provide a new paradigm for heterogeneous (photo)chemistry at temperatures below those required for a QLL to form at the ice surface