P38 MAP kinase is activated at early stages in Alzheimer's disease brain

The regional, cellular, and subcellular localization of phosphorylated p38 MAPK (pp38) was examined by immunocytochemistry, immuofluorescent multiple labeling, and immunoblotting of extracts as well as immunoprecipitates of human postmortem tissue from control and Alzheimer's disease (AD) cases at different Braak stages. "Early AD" cases (Braak stages IV-V) and a subset of Braak stage VI cases have high levels of pp38 immunoreactivity, with the most dense immunoreactivity located in CA2 and subiculum followed by CA1 in the hippocampus. On the contrary, very little pp38 was detected in age-matched controls (Braak stages 0-II). More importantly, as revealed by various multiple labeling experiments, pp38 immunoreactivity is mainly located in neurons bearing early neurofibrillary pathology, but not in typically fibrillar tangles that are densely stained by thioflavin-S. Most pp38-positive neurons only contain a small amount of phospho-tau. Additionally, pp38 immunoreactivity was not associated with senile plaques. At the subcellular level, pp38-immunoreactive granules are usually larger than the granules stained with the lysosomal marker cathepsin D. Immunoblotting with different extraction buffers and immunoprecipitation indicate that pp38 does not or only loosely binds to phospho-tau. Taken together, this study demonstrates that p38 MAPK is activated at early stages of neurofibrillary degeneration in AD hippocampus. The p38 activation may also be linked to neurodegeneration through mechanisms other than neurofibrillary tangle formation.     

Functional prognosis of paraplegia due to cord ischemia: a retrospective study of 23 patients

The functional prognosis of spinal cord infarct is not well known, complicating care of patients suffering from ischemic paraplegia. The aim of this study was to evaluate the clinical and functional outcome of patients with spinal cord infarct treated in rehabilitation centers in order to identify factors influencing functional outcome. We studied cases of non-trauma-related paraplegia treated between 1992 and 1999. Spinal compression and infectious and inflammatory myelopathy were excluded. Age, gender, cardiovascular risk factors, initial and final clinical findings according to the American Spinal Injury Association (ASIA/IMSOP) criteria, MRI findings, and initial urodynamic findings were analyzed. Two groups were identified regarding extension of the spinal cord infarct to the cone or not. Assessment of functional outcome was based on the Frankel classification, ambulatory ability, wheelchair use, and bladder control. Cases of spinal cord infarct were then classified according to extension to the cone or not, determined on the basis of initial clinical, MRI, and urodynamic findings. Twenty-three patients (19 males and 4 females) were selected for analysis. Mean age was 54 years, with no mortality during the follow-up period. At discharge, the group of nine patients whose infarct had not extended to the medullary cone had a significantly better motor recovery using the ASIA motor score (p<0.01). Patients whose infarct did not extend to the cone used wheelchairs less often, were more often in Frankel class D (p<0.05), and had normal bladder control more often (p<0.05) than patients whose infarct extended to the cone. Lack of extension to the medullary cone appeared to be a factor predictive of better functional outcome.     

Recovery from gastric mucus depletion in the intact guinea pig mucosa

BACKGROUND: In developed countries one-third of the population is infected with the gastric pathogen Helicobacter pylori. In the early stages of H. pylori-induced gastritis, typical symptoms include gastric erosions and mucus depletions. Artificial mucus depletion was generated, demonstrating both consequent irritation and recovery processes in the mucosa. METHODS: The mucus depletion was examined by removing a small cylinder of mucus from the surface of the explanted guinea pig corpus mucosa, leaving the epithelial surface intact. pH microelectrodes were inserted into the mucosa in vitro, measuring the epicellular mucus pH, the pH(i) of the underlying epithelial cells and the pH inside the gastric glands during mucus regeneration. Using infrared microscopy, the same process of mucus layer renewal was followed in anaesthetized animals. RESULTS: The depletion exposed the tissue surface to low luminal pH levels. At a luminal pH of 2.5, a decrease was observed in the crypt outlet pH and surface cell pH(i), while deeper cells were less affected. However, a subsequent neutralization in the deep gland lumen was found. During the repair process, a quarter of the mucus layer was regenerated within the first 5 min. This newly secreted mucus formed a structure similar to that before depletion. Within 45 min, pH(i) and tissue-near pH values had fully recovered. CONCLUSION: Following mucus depletion, there is a decrease in surface cell pH(i) and crypt outlet pH values. The repair process is then characterized by extensive mucus secretion and local cessation of acid secretion.     

Influence of hydration on dihydroxyacetone-induced pigmentation of stratum corneum

Dihydroxyacetone, the browning ingredient in sunless tanning formulations, reacts with amino acids in the outer stratum corneum to form a mixture of high molecular weight pigments. Our initial observations indicated that high hydration of dihydroxyacetone-treated skin completely inhibited development of pigmentation. To investigate the mechanism underlying this effect, studies were carried out in isolated murine epidermis, polyvinyl alcohol/lysine films, and lysine in glycerol/water solvent. Murine epidermis treated with dihydroxyacetone showed a biphasic dependence on relative humidity: maximum pigmentation developed at 84% relative humidity and minimum pigmentation at 0% and 100% relative humidity. Filaggrin proteolysis, which shows a similar dependence on relative humidity and provides free amino acids in the outer stratum corneum, did not account for the relative humidity dependence of dihydroxyacetone pigmentation. A similar biphasic pigmentation response was obtained when polyvinyl alcohol film containing lysine was treated with dihydroxyacetone and incubated at various relative humidities, indicating that the structure of the stratum corneum was not a major factor. To remove the influence of the matrix, the reaction of dihydroxyacetone with lysine was followed at varying concentrations of water in mixed glycerol/buffer solvent. Again, greater pigment formation was found at an intermediate level of water (6% vol/vol) and little pigmentation at 0% and 100% water content. These results are consistent with a requirement for water at low relative humidity, which facilitates formation of free amine groups needed for the initial reaction with dihydroxyacetone, and with inhibition of the dehydration reactions by water through the law of mass action at high relative humidity.     

Subcutaneous T-cell lymphoma

A 70-year-old woman presents with a 2-year history of intermittent, subcutaneous nodules. The patient was otherwise asymptomatic. A biopsy specimen was consistent with a subcutaneous T-cell lymphoma, a rare subset of peripheral T-cell lymphoma; when accompanied by the hemocphagocytic syndrome, it can be rapidly fatal. The histopathologic characteristics and nature of the disease are discussed.     

Meta-analysis of the effects of endothelin receptor blockade on survival in experimental heart failure

BACKGROUND: Although an initial study of endothelin receptor blockade reported positive findings, subsequent experiments and clinical trials in humans found little or no benefit. METHODS: We applied meta-analytic methods to assess the methodologic rigor of preclinical studies of endothelin blockade and to quantitatively evaluate the totality of evidence regarding the effect of endothelin receptor blockers in experimental heart failure. A total of 396 animals were assigned to control and 594 were assigned to experimental therapy in the pooled analysis. Of the 9 studies identified, no study reported a priori sample size justification. Although there was a tendency to increased mortality with early administration (relative risk 1.39, P=.15) and decreased mortality with late administration (relative risk 0.85, P=.6), in the overall analysis, there was no significant evidence of benefit or harm (relative risk 1.03, P=.9). Studies with a small sample size had estimated effects that tended to deviate further from the pooled estimate of all studies. CONCLUSIONS: Consideration of mortality effects in the totality of studies revealed no significant effect of endothelin antagonists in animal models of experimental heart failure. Given the potential for between-study variability, reliance on studies with small sample size may lead to unrealistic expectations when extrapolating preclinical experimental results to future research.     

Incorporation and integration of implanted myogenic and stem cells into native myocardial fibers: anatomic basis for functional improvements

BACKGROUND: Myoblasts and stem cells implanted into myocardium can differentiate into myocytes and may functionally improve impaired ventricles. For implanted cells to actually contribute to the synchronous contractions of the heart, however, they must be anatomically integrated with the existing native myocardial fibers. METHODS: Isogenic Lewis rats were used as donors and recipients to simulate clinical autotransplantation. Either skeletal myoblasts or marrow stromal stem cells were isolated from donors, culture expanded, and labeled with 4',6-diamidino-2-phenylindole (4',6-diamidino-2-phenylindole). Labeled cells were then injected into the myocardium of recipients. At intervals specimens were obtained, sectioned, and stained with hematoxylin and eosin and immunohistochemically against connexin-43 to demonstrate gap junctions (intercalated discs). RESULTS: At 1 week the labeled cells were still undifferentiated, but early expression of connexin-43 could be detected at contact points between the implanted cells and the native myocytes. By 4 to 6 weeks, labeled, fully differentiated myocytes could be seen to interconnect among themselves and with native cardiomyocytes by means of intercalated discs. In sections parallel to the myofibers, full integration of new labeled myocytes with the native myofiber cells could be observed. Furthermore, the labeled myofibers were in parallel with the native, unlabeled fibers. We postulate that such supracellular structural integration was enhanced by fiber stretching during cardiac contractions, sending signals for cellular reorientation and incorporation, in which the cytoskeletal system may play an important role. CONCLUSION: We conclude that implanted precursor cells can be integrated into native myocardial structure so as to contribute to myocardial function. Direct cell-to-cell contact seems to be an important signaling mechanism, which has implications for cellular implantation strategies.