Thrombin regulates components of the fibrinolytic system in human mesangial cells

Besides its procoagulant activity, thrombin has been shown to stimulate cell proliferation and to regulate the fibrinolytic pathway. We report here the effect of purified human alpha thrombin on the synthesis of tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor 1 (PAI-1) by cultured human mesangial cells. Thrombin (0 to 2.5 U/ml) increased in a time- and dose-dependent manner the production of t-PA and PAI-1 (2- to 3-fold increase of secreted t-PA and PAI-1 release during a 24 hour incubation). This effect was associated with a twofold increase in DNA synthesis measured by 3H-thymidine incorporation. Zymographic analysis and reverse fibrin autography showed that thrombin also increased the level of the 110 Kd t-PA-PAI-1 complex, whereas PAI-1 was present as a free 50 Kd form in the culture medium conditioned by unstimulated and thrombin-stimulated cells. Free t-PA was never observed. Both membrane binding and catalytic activity of thrombin were required since the effects of 1 U/ml thrombin were inhibited by addition 2 U/ml hirudin, which inhibits the membrane binding and catalytic activity of thrombin, and since DFP-inactivated thrombin, which has the ability to bind but which has no enzymatic activity, did not induce t-PA or PAI-1. Gamma thrombin, which does not bind to thrombin receptor, did not increase t-PA and PAI-1 releases. The effects of thrombin were probably mediated by protein kinase C activation since H7, an inhibitor of protein kinases, inhibited significantly thrombin effects on t-PA and PAI-1 production, and since addition of an activator of protein kinase A, 8-bromocyclic AMP (100 microM), induced a significant inhibition of the thrombin effect. The effects of thrombin were also suppressed by 1.25 micrograms/ml alpha amanitin, suggesting a requirement of de novo RNA synthesis. Northern blot analysis indicated that thrombin induced an increase in the mRNA levels of t-PA and of PAI-1. We conclude that thrombin increases DNA synthesis in human mesangial cells and enhances the synthesis of both t-PA and PAI-1. The latter is released in a large excess as compared to t-PA. Hence, thrombin may have a role in provoking a localized hypofibrinolytic state and may contribute to the persistence of glomerular fibrin deposits during proliferative glomerulonephritis.     

Plant nurseries: a reliable resource for plant identification?

Poison Centers frequently rely on the assistance of local plant nurseries to identify unknown plants involved in exposures. The reliability and accuracy of utilizing this method has never been studied; therefore, our objective was to evaluate this primary resource of plant identification. A study was done in which callers were instructed to take plant samples to a local nursery for visual identification. Once the patient was treated according to our normal protocol, the plant specimen was sent to a botanist for a second identification. The botanist provided his identification results through a blinded process. The collected data was gathered from 68 cases that completed the necessary study criteria. In 58% of the cases, plant nurseries were an unreliable source for plant identification. These incorrect identifications resulted in the "undertreatment" in 24% of the exposures.     

Social validation in aphasiology: Does judges' knowledge of aphasiology matter?

Background: Social validity assessments can be used to examine clinical significance of changes due to treatment of aphasia. Behavioural researchers have noted the need to investigate various methodological issues in social validity research. For example, differences in rater characteristics have been noted to influence social validation ratings of treatment outcomes.Aims: This study examined the possibility of differences in social validity ratings across judges with varying degrees of knowledge of and experience with aphasia. The secondary purpose was to replicate results of previous research that showed the clinical significance of communication partner training. Research questions included: (1) Does the level of knowledge of aphasia and experience with persons with aphasia result in a difference in social validity ratings of pre- and post-training conversations between a student volunteer and an elder with aphasia? (2) Will the significant social validity findings previously obtained from members of the extended community be replicated (Hickey, 2000)?Methods & Procedures: Ten naïve individuals (no familiarity with aphasia), ten second-year graduate students majoring in speech-language pathology (some familiarity with aphasia), and ten Speech-Language Pathologists served as judges. After watching two pre- and two post-training videotaped conversations, the judges provided ratings for seven dimensions of conversations to examine clinical significance of changes in pre- and post-training conversations between a student volunteer and an elder with aphasia. A mixed design with between and within subjects effects, and interaction effects was used.Outcomes & Results: Repeated measures ANOVA revealed significant main effects for group on two items, significant main effects for training on all seven items, and significant interaction effects for five items. Pre-training ratings showed greater variability than post-training ratings. Naïve judges provided the lowest pre-training ratings, and generally, the most change in pre- and post-training ratings. Post-training ratings of the three groups became more similar.Conclusions: This study suggests that truly naïve judges who are representative of the general public may provide the most robust findings in social validation studies of aphasia treatment outcomes. However, further research is needed to determine the source of variability beyond level of knowledge of aphasia. This study also replicated the results of previous research by revealing the clinical significance of communication partner training for elders with aphasia.     

Fibrosis Progression According to Epithelial‐Mesenchymal Transition Profile: A Randomized Trial of Everolimus Versus CsA

Markers of epithelial‐mesenchymal transition (EMT) may identify patients at high risk of graft fibrogenesis who could benefit from early calcineurin inhibitor (CNI) withdrawal. In a randomized, open‐label, 12‐month trial, de novo kidney transplant patients received cyclosporine, enteric‐coated mycophenolate sodium (EC‐MPS) and steroids to month 3. Patients were stratified as EMT+ or EMT? based on month 3 biopsy, then randomized to start everolimus with half‐dose EC‐MPS (720 mg/day) and cyclosporine withdrawal (CNI‐free) or continue cyclosporine with standard EC‐MPS (CNI). The primary endpoint was progression of graft fibrosis (interstitial fibrosis/tubular atrophy [IF/TA] grade increase ≥1 between months 3–12) in EMT+ patients. 194 patients were randomized (96 CNI‐free, 98 CNI); 153 (69 CNI‐free, 84 CNI) were included in histological analyses. Fibrosis progression occurred in 46.2% (12/26) CNI‐free EMT+ patients versus 51.6% (16/31) CNI EMT+ patients (p = 0.68). Biopsy‐proven acute rejection (BPAR, including subclinical events) occurred in 25.0% and 5.1% of CNI‐free and CNI patients, respectively (p < 0.001). In conclusion, early CNI withdrawal with everolimus initiation does not prevent interstitial fibrosis. Using this CNI‐free protocol, in which everolimus exposure was relatively low and administered with half‐dose EC‐MPS, CNI‐free patients were overwhelmingly under‐immunosuppressed and experienced an increased risk of BPAR.