Oxidative stress-inducible protein tyrosine phosphatase in glomerulonephritis

Previously we found that rat mesangial cells express 3CH134/CL100 protein-tyrosine phosphatase (PTPase) in response to reactive oxygen intermediates (ROIs), and we now extend these studies to glomerulonephritis (GN), where ROI have been demonstrated to play a role. The rat homologue of 3CH134/CL100 was cloned from a rat macrophage cDNA library. The rat 3CH134/CL100 mRNA was strongly induced in the lung, liver, and heart the first day after birth, suggesting that hyperoxic adaption might be involved in the induction of the PTPase mRNA. In anti-glomerular basement membrane (GBM) antibody (Ab) GN in rats, the 3CH134/CL100 PTPase mRNA was expressed in glomeruli as early as 30 minutes after anti-GBM Ab injection. The 3CH134/CL100 mRNA expression was modulated by the ROI scavenger dimethylthiourea (DMTU), indicating that its induction was ROI related. In contrast to the glomerular lesion, PTPase mRNA expression was not induced in experimental tubulointerstitial nephritis. In situ hybridization suggested that mesangial and some infiltrating cells were the major glomerular cell sources of the PTPase mRNA. These results indicate that rat CCH134/CL100 PTPase is actively induced in glomeruli as part of an acute immune injury at least in part related to oxidative stress. PTPase induction in GN and potentially other forms of inflammation may play an important regulatory role in protein kinase signaling pathways.     

Evaluation of the cellulolytic capacity of Ascobolus furfuraceus (Fungi, Ascomycotina)

Growth kinetic variables (dry weight, mycelial protein, extracellular protein and pH evolution) were measured in Ascobolus furfuraceus cultures either with soluble cellulose (CMC) or crystalline cellulose as only carbon sources. When growing on CMC the mycelial protein production reached a maximum at 14 days, while the extracellular protein was maximal at 17 days. On crystalline cellulose more delay was observed (4 and 14 days, respectively). Straight lineal correspondence (r = 0.9883) was observed between the extracellular protein production and enzymatic activity kinetics, showing parallel behavior of these variables. When the biomass and extracellular protein production rates were analysed, the maxima were observed at diverse growth stages. For CMC, the dry weight production rythm precedes the cellulolytic system liberation rythm (maxima at 9 and 14 days, respectively). When crystalline cellulose was the substrate, the maximal rates were inverse, 16th day for biomass production rythm and 12th day for enzyme release rythm. On the basis of such tests and analyses, a model to explain cellulose degration by A. furfuraceus, is proposed.     

Prediction of fatigue screw loosening in anterior spinal fixation using dual energy x-ray absorptiometry

STUDY DESIGN: A biomechanical study was performed to investigate a relation between the bone mineral density of the vertebral body and the number of loading cycles to induce fatigue loosening of an anterior vertebral screw. OBJECTIVES: The objective of this study was to investigate the potential usefulness of dual energy x-ray absorptiometry of measuring bone mineral density of the vertebral body in predicting the fatigue loosening of th anterior vertebral screw. SUMMARY OF BACKGROUND DATA: Loosening of the vertebral body screw is a well know failure in spinal instrumentation, and more commonly observed than pullout failure. The relation between bone mineral density and pullout strength of the screw has been investigated previously, but no studies are available on the fatigue loosening in anterior spinal fixation. METHODS: Bone mineral density was measured using dual energy x-ray absorptiometry and the screw loosening was produce by a cyclic loading in the cephalad-caudal direction. Screw loosening was defined as 1 mm displacement of the screw relative to bone, and the number of loading cycles to induce the screw loosening was obtained and statistically correlated with bone mineral density. RESULTS: There was a positive correlation between the number of loading cycles to induce screw loosening and bone mineral density (R = 0.8, P < 0.01). The average number of loading cycles to induce screw loosening was significantly less for specimens with bone mineral density < 0.45 g/cm2 compared to those with bone mineral density > or = g/cm2. CONCLUSIONS: These findings suggest that bone mineral density may be a good predictor of anterior vertebral screw loosening. Bone mineral density < 0.45 g/cm2 may be critical value of loosening of the anterior vertebral body screw. However, further biomechanical and clinical studies are required before using threshold value clinically.     

Intracellular signaling events during positive and negative selection of CD4+CD8+ thymocytes in vitro

We have used in vitro models of thymocyte positive and negative selection in conjunction with selective inhibitors of the TCR-mediated signaling cascade to investigate the intracellular signaling events that mediate these processes. We report that Ro 31.8425, a potent and selective inhibitor of protein kinase C, which blocks the activation of mature T cells in a dose-dependent fashion, has no effect on either positive or negative selection of CD4+8+ thymocytes. In contrast, cyclosporin A fails to prevent negative selection, but inhibits positive selection through a direct effect on developing thymocytes, rather than through the perturbation of stromal cell support. Thus, our data suggest that positive and negative selection may operate via distinct intracellular signaling pathways.     

Prevalence and correlates of depressive syndromes among adults visiting an Indian Health Service primary care clinic

Depression is common among patients visiting primary care clinics. In order to describe the prevalence of depressive syndromes in an American Indian primary care clinic population and to help define the clinical correlates of depressive syndromes in this setting, a clinic-based research study of depression was undertaken by the Indian Health Service (IHS). One hundred and six patients from an IHS primary care clinic were systematically enlisted for participation in the study. Participants completed the Inventory for Diagnosing Depression (IDD). Twenty-two (20.7%) responded with answers scoring positive for a depressive syndrome. Nine of these 22 (8.9% of the 106 participants) met IDD criteria for a major depressive syndrome. A diagnosis of depression, a past history of depression, use of mental health facilities, unexplained pains, and antidepressant medication use were associated with the presence of a depressive syndrome.