Nuclear CSPP1 expression defined subtypes of basal-like breast cancer.

BACKGROUND: The multi-exon CSPP1 gene, encoding for centrosome and microtubule-associated proteins involved in ciliogenesis and cell division, is a candidate oncogene in luminal breast cancer but expression of CSPP1 proteins remained unexplored. METHODS: CSPP1 gene and protein expression was examined in normal mammary tissue, human breast cancer cell lines, and primary breast cancer biopsies from two patient cohorts. Cell type and epitope-dependent subcellular-specific CSPP1 staining pattern in normal mammary gland epithelium and cancer biopsies were correlated to molecular and clinical parameters. RESULTS: A novel, nuclear localised CSPP1 isoform was exclusively detected in luminal epithelial cells, whereas cytoplasmic CSPP-L was generally expressed in normal mammary epithelium. Luminal cell-related nuclear CSPP1 expression was preserved in type-matched cell lines and carcinomas, and correlated to gene copy number and mRNA expression. In contrast, basal-like carcinomas displayed generally lower CSPP1 mRNA expression. Yet, a subgroup of basal-like breast carcinomas depicted nuclear CSPP1 expression, displayed luminal traits, and differed from nuclear CSPP1 devoid counterparts in expression of eight genes. Eight-gene signature defined groups of basal-like tumours from an independent cohort showed significant differences in survival. CONCLUSIONS: Differential expression of a nuclear CSPP1 isoform identified biologically and clinically distinct subgroups of basal-like breast carcinoma.

Prognostic importance of DNA ploidy and DNA index in stage I and II endometrioid adenocarcinoma of the endometrium.

BACKGROUND: We evaluated the prognostic importance of DNA ploidy in stage I and II endometrioid adenocarcinoma (EAC) of the endometrium with a focus on DNA index. PATIENTS AND METHODS: High-resolution DNA ploidy analysis was carried out in tumor material from 937 consecutive patients with International Federation of Gynecology and Obstetrics (FIGO) stage I and II EAC of the endometrium. RESULTS: Patients with diploid (N = 728), aneuploid tumor with DNA index ≤ 1.20 (N = 118), aneuploid tumors with DNA index >1.20 (N = 39) and tetraploid tumor (N = 52) had 5-year recurrence rates 8%, 14%, 20% and 12%, respectively. Patients with aneuploid tumor with DNA index >1.20 had a poorer 5-year progression-free survival (67%) and overall survival (72%) compared with the patients with aneuploid tumor with DNA index ≤ 1.20 (81% and 89%, respectively). Aneuploid tumors with DNA index ≤ 1.20 relapsed mainly in the vagina and pelvis, whereas aneuploid tumors with DNA index >1.20 relapsed predominantly outside pelvis. CONCLUSIONS: The recurrence risk for the patients with aneuploid tumor is higher than the patients with diploid tumor in EAC of the endometrium. Based on DNA index with cut-off 1.20, aneuploid tumors can be separated into two subgroups with different recurrence pattern and survival.

Measurement of apoptosis in cytological specimens by flow cytometry: comparison of Annexin V, caspase cleavage and dUTP incorporation assays.

OBJECTIVE: To compare the performance of different assays for measuring apoptosis in cytological specimens. METHODS: Apoptosis was assessed in 27 specimens (22 effusions, five fine needle aspirates; 20 malignant, seven reactive) using flow cytometry, applying assays for the measurement of annexin V expression, caspase-3 and -8 cleavage and deoxynucleotidyl transferase deoxyuridine triphosphates (dUTP) incorporation. Results were studied for differences between reactive and malignant specimens, as well as performance across assays. RESULTS: Wide variation in the degree of apoptosis was observed in both benign and malignant specimens using all assays. However, the percentage of annexin V-positive cells was higher compared with those showing caspase cleavage or dUTP incorporation in the majority of cases, irrespective of specimen type. Comparative analysis of benign and malignant specimens showed no significant differences in expression of any of the studied parameters. However, tumour cells and reactive mesothelial cells in pleural effusions had a significantly lower level of dUTP incorporation compared with their counterparts in peritoneal specimens (P = 0.001). CONCLUSIONS: The present data are in agreement with our previous observation in ovarian carcinoma effusions, that measurement of apoptosis by the annexin V assay provides higher expression values than those obtained by other assays, suggesting that this assay does not accurately reflect the degree of apoptosis in benign or malignant cells in effusions.

Flow cytometric measurement of cellular FLICE-inhibitory protein (c-FLIP) in ovarian carcinoma effusions.

OBJECTIVE: The objective of this study was to establish a flow cytometry assay for measuring c-FLIP in serous effusions. In addition, we studied the clinical relevance in ovarian carcinoma effusions of this inhibitor protein in the death receptor signalling pathway of apoptosis. METHODS: Two c-FLIP antibodies were tested using Western blotting and the best performing one was used for titration of c-FLIP expression in a panel of five cell lines, consisting of ovarian carcinoma, breast carcinoma and malignant mesothelioma. The concentration that provided the best signal-to-noise ratio was used for comparison of the performance of three fixation and permeabilization protocols. The best performing protocol was chosen for analysis of 69 ovarian carcinoma effusions. c-FLIP expression was analysed for association with clinicopathological parameters and survival. RESULTS: Rabbit polyclonal c-FLIP by Abcam and the IntraStain kit by Dako performed best. c-FLIP expression was detected in tumour cells in all 69 effusions (expression range 21-100%, median = 80%). No association was found between c-FLIP expression and clinicopathological parameters, including chemoresponse and survival. However, an inverse correlation was found between c-FLIP levels and expression of the previously studied apoptosis marker cleaved caspase-3 (P = 0.029). CONCLUSIONS: An assay for measuring c-FLIP in cytology specimens is presented. c-FLIP is frequently expressed in ovarian carcinoma effusions, but its expression appears to be unrelated to disease aggressiveness.

Effect of varicose vein surgery on venous reflux scoring and plethysmographic assessment of venous function.

BACKGROUND: Colour duplex ultrasonography (CDU) is widely recommended before varicose vein surgery, combined with quantification of venous reflux by plethysmography where required. This study assessed venous haemodynamics before and after varicose vein surgery by venous outflow plethysmography (VOP), venous reflux plethysmography (VRP) and by adoption of a modified segmental venous reflux score (VRS). The effect of wearing one or two class I medical compression stockings was also assessed. The aim of the study was to identify parameters which reflect the outcome of treatment using medical compression stockings or surgical intervention. METHODS: 24 legs of 21 patients with superficial vein incompetence of clinical grade C(2-4a) (CEAP) were assessed before and a mean of 8 S.D. 4 months after superficial vein surgery. Investigations were CDU, as well as VOP and VRP using mercury in rubber gauges fitted either around the calf or the forefoot. Venous reflux was semi-quantitatively graded by CDU in relation to the actual vein diameter and transformed into a VRS with respect to the number of involved serial vein segments. The venous reflux rates were measured in standing patients after knee bending before and after application of one or two superimposed compression stockings (class I). RESULTS: According to VRP, one compression stocking reduced the maximum venous reflux rates (VR(max)) by about 30% which was comparable with the effect of surgery on VR(max). Two superimposed compression stockings were almost twice as effective and diminished VR(max) pre- and post operatively by around 60%. Varicose surgery reduced the maximum venous outflow rates significantly (pre-op: 166 S.D. 77 ml/min x 100 ml tissue, post op: 120 S.D. 34) and improved VRS (pre-op median 5.0 IQR: 4.5-5.5, post-op median 0.5 IQR: 0-1.0). Surgery had no effect on venous refilling time or venous reflux rates when measured without compression stockings. CONCLUSION: Venous reflux assessed by plethysmography was moderated by the use of compression stockings pre-operatively but did not reflect the outcome of surgical treatment of superficial venous reflux. Increased venous volume and venous outflow were restored to the levels of normal contralateral limbs by surgery. The VRS decreased considerably following surgery, reflecting the effect of surgical treatment on the number of incompetent venous segments. Changes in this parameter did not correlate with any of the plethysmographic measurements.

Effect of shear stress on the expression of coagulation and fibrinolytic factors in both smooth muscle and endothelial cells in a co-culture model.

UNLABELLED: Blood vessels are subjected to forces due to the flow. Endothelial cells (EC) are recipients, cross-talk with smooth muscle cells (SMC), and regulate physiology. It was hypothesized that both EC and SMC respond to shear stress, which alters the expression of factors in coagulation and fibrinolysis. METHODS: A co-culture of human saphenous vein EC (HSVEC) and human saphenous vein SMC (HSVSMC) was exposed to shear, following which the cells were separated. Gene expression of tissue factor, thrombomodulin (TM), plasminogen activator inhibitor-1 (PAI-1), tissue plasminogen activator (tPA) and urokinase plasminogen activator (uPA) were analyzed with real-time RT-PCR. Protein expression was studied with ELISA. In HSVEC, the expression of PAI-1 (x2.1), tPA (x1.8), uPA (x1.6), tissue factor (x2.5) and TM (x1.9) was upregulated after 4 h of shear compared to controls. After 24 h of shear, expression was still upregulated in tPA (x2.3) and TM (x1.6). In HSVSMC, change in expression of PAI-1 (x2.1) was present after 4 h and in uPA (x2.1), and TM (x0.4) after 24 h. Both HSVEC and HSVSMC responded to shear, which led to altered expression of coagulation and fibrinolytic factors. This indicates that SMC, and interactions between EC and SMC, are more important in the regulation of vascular wall hemostasis than earlier studies have reported.

The reciprocal translocation t(9;16)(q22;p13) is a primary chromosome abnormality in basal cell carcinomas.

The reciprocal translocation t(9;16)(q22;p13) was identified in three short-term cultured basal cell carcinomas (BCCs). The t(9;16) was the sole anomaly in one clone in two tumors and was accompanied by a second change that also affected the long arm of chromosome 9 in the third. In addition, other cytogenetically unrelated abnormal clones were also found in all three BCCs. The identification of t(9;16)(q22;p13) as a primary chromosomal abnormality in a subset of BCCs (we found it in 3 of 22 tumors) is especially intriguing against the background that the PTCH gene, which when mutated in the germ line presumably gives rise to the autosomal dominant basal cell nevus or Gorlin's syndrome, maps to chromosome band 9q22. None of the genes rearranged in the BCC-specific t(9;16)(q22;p13) translocation have been identified, but we hypothesize that the translocation represents the cytogenetic corollary of a tumorigenic recombination of PTCH with an as yet unknown gene in 16p13. If so, this would be the first time that a tumor suppressor gene causally involved in a hereditary cancer is shown to be frequently rearranged through a specific translocation in sporadic carcinomas of the same type.

Expression levels of the nerve growth factor receptors TrkA and p75 in effusions and solid tumors of serous ovarian carcinoma patients.

PURPOSE: The purpose of this study was to analyze the expression of the high- and low-affinity nerve growth factor (NGF) receptors TrkA and p75 in effusions and in primary and metastatic tumors of serous ovarian carcinoma patients, as well as to evaluate their association with clinicopathological parameters and disease outcome. EXPERIMENTAL DESIGN: Sections from 77 malignant effusions and 78 primary and metastatic lesions were evaluated for protein expression of TrkA and p75 using immunohistochemistry (IHC). Expression of the phosphorylated form of TrkA (p-TrkA) was evaluated in 75 effusions using IHC. TrkA and p75 mRNA expression was studied in 44 effusions using reverse transcription-PCR (RT-PCR). RESULTS: TrkA protein membrane expression was detected in carcinoma cells in 30 of 77 (39%) effusions and 64 of 78 (82%) solid tumors. The decrease in TrkA expression in effusions approached, but did not reach, statistical significance when only corresponding lesions were analyzed (P = 0.06 in the comparison of effusions and primary tumors, P = 0.09 for effusions and metastases). Conversely, p75 protein membrane expression was more common in effusions, which was detected in 16 of 77 (21%) effusions as compared with 6 of 78 (8%) solid tumors (P > 0.05 in analysis of corresponding lesions). Expression of p-TrkA in carcinoma cells was limited to 5 of 75 effusions. Interestingly, 11 of 16 p75-positive effusions were also immunoreactive for the antibody against TrkA (P = 0.001), suggesting NGF activation using two signaling pathways. TrkA and p75 protein expression in tumor cells was similar in pleural and peritoneal effusions (P > 0.05). Using reverse transcription-PCR, TrkA mRNA was detected in 2 of 45 effusions, whereas p75 mRNA was present in 3 of 45 specimens. TrkA and p75 showed no association with tumor grade, Fédération Internationale des Gynaecologistes et Obstetristes stage, chemotherapy status, the extent of residual disease, or survival (P > 0.05). CONCLUSIONS: TrkA and p75 are both expressed in advanced-stage ovarian carcinoma, but whereas p75 expression is elevated in effusions, TrkA shows an opposite trend. The different expression of NGF receptors in effusions may relate to the different microenvironment and growth factor availability in body cavities, as also supported by the infrequent activation of TrkA in effusions. The similar expression of TrkA and p75 in carcinoma cells in pleural and peritoneal effusions provides further evidence for our hypothesis that there are few, if any, phenotypic differences between ovarian carcinoma cells at these two sites. TrkA and p75 expression in effusions does not appear to be a predictor of disease outcome in advanced-stage serous ovarian carcinoma.

Expression of CD44 in effusions of patients diagnosed with serous ovarian carcinoma--diagnostic and prognostic implications.

CD44 is a family of cell adhesion molecules involved in a variety of cellular functions. The present study analysed the expression of two CD44 isoforms in serous effusions of patients diagnosed with ovarian carcinoma and corresponding primary and metastatic lesions. Fifty-eight effusions, 23 primary ovarian tumours, and 44 metastatic lesions were studied for protein expression of CD44s and v3-10 using immunohistochemistry. Results were correlated with clinical parameters. CD44v3-10 was seen in carcinoma cells in the majority of cases at all sites. Malignant effusions showed an up-regulation of CD44s compared to both primary tumours and metastatic solid lesions. Mesothelial cells frequently expressed CD44s, but were rarely immunoreactive for v3-10. CD44s immunoreactivity in cancer cells in effusions was significantly more often observed in patients with FIGO stage 3 than in stage 4 patients (P = 0.045). Staining results did not correlate with age, effusion site, metastatic site, tumour grade or residual tumour mass after initial surgery. Likewise, comparison of overall and disease-free survival with expression of the CD44 isoforms studied did not reveal any statistically significant associations. The up-regulation in CD44 levels in effusions, primarily in stage 3 disease, suggests that adhesion of ovarian carcinoma cells to mesothelium may be regulated at the level of CD44s expression, and provides further evidence of phenotypic alteration in the transition from primary tumour cell clones to effusions. The similar expression profile of CD44 in carcinoma cells in peritoneal and pleural effusions supports our previous observations and the hypothesis that carcinoma cells in peritoneal effusions are truly metastatic.

Angiogenesis in invasive breast carcinoma--a prospective study of tumour heterogeneity.

Assessment of angiogenesis has been reported to be an independent prognostic factor in breast cancer, while other studies have been negative. This study prospectively investigates the degree of intratumoral microvessel heterogeneity and the possible influence on the results. From 21 invasive breast cancers six 4 micro sections were cut. Sections (n=126) were stained immunohistochemically with a CD31 monoclonal antibody (JC70). In each section, three areas with the most intense neovascularisation (hot spots) were identified and the microvessel density (MVD) was obtained by counting vessels at 200x magnification. The variation between sections contributed more to the total variance than variation between different tumours: 45.0 and 37.3%, respectively, according to a nested ANOVA analysis. Paired comparisons of two sections at a time from the same tumour showed a concordance in 59.0% (95% Confidence Interval (CI): (55.3-62.8)) with reference to a tentative cut-off level. Our study demonstrates that assessment of MVD in hot spots is questionable to measure angiogenesis due to the considerable intratumoral heterogeneity.

Ovarian carcinoma cells in serous effusions show altered MMP-2 and TIMP-2 mRNA levels.

The expression of matrix metalloproteinases (MMP) and their inhibitor TIMP-2 in serous effusions from patients with ovarian carcinoma and its association with clinico-pathological parameters were analysed. The findings in carcinoma cells in effusions were compared with corresponding primary and metastatic lesions. Sixty-six effusions and 96 tissue sections were stained for MMP-1, MMP-2 and MMP-9 applying immunohistochemistry (IHC) and analysed for MMP-2, MMP-9 and TIMP-2 expression using mRNA in situ hybridisation (ISH). MMP-2 and MMP-9 mRNA levels in 30 effusions were subsequently analysed using reverse transcription- polymerase chain reaction (RT-PCR). MMP and TIMP expression was detected in both carcinoma and mesothelial cells in effusions. The levels were consistently higher in malignant cells, significantly so for MMP-1 (P=0.016) and MMP-2 (P=0.036) proteins, as well as for TIMP-2 mRNA (P=0.008). In tissue sections, MMP-1, MMP-2 and MMP-9 protein expression was mostly localised to tumour cells, while MMP-2, MMP-9 and TIMP-2 mRNA were predominantly detected in stromal cells. Adenocarcinoma cells in effusions showed a significant upregulation of MMP-2 expression compared with primary tumours, with a concomitant downregulation of TIMP-2. RT-PCR demonstrated the presence of MMP-2 and MMP-9 in 28/30 and 0/30 specimens, respectively. MMP and TIMP are thus mainly synthesised by cancer cells in effusions, while stromal cells have a similar role in solid tumours. MMP-1 and MMP-2 production predominates over that of MMP-9 in effusions. Increased MMP-2 and reduced TIMP-2 levels are seen in ovarian carcinoma cells in effusions, possibly marking the acquisition of a metastatic phenotype.

Quantitative analysis of specific mRNA species in minute cell samples by RT-PCR and flow cytometry.

A method for the quantitative determination of specific mRNAs in small numbers of cells, freshly isolated from tissues or early cell cultures, was developed by combining quantitative reverse transcription-polymerase chain reaction (RT-PCR) and quantitative flow cytometry. Freshly isolated umbilical vein endothelial cells were sorted by flow cytometry and then lysed. The number of cells in the lysate was determined by counting of nuclei after propidium iodide staining using flow cytometry. The number of plasminogen activator inhibitor-1 (PAI-1) mRNA copies per cell was determined by quantitative RT-PCR using point-mutated PAI-1 cRNA as an internal standard. The cells were shown to contain 400-900 copies of PAI-1 mRNA molecules per cell which confirms that endothelial cells in vivo express PAI-1. PAI-1 mRNA expression was also analyzed in small numbers of endothelial cells in primary culture in basal conditions and after incubation with different interleukins. The method allowed reliable and reproducible estimation of the number of mRNA copies per cell from original cell samples containing less than 1000 cells. This method can be used for the quantitative determination of various mRNA species in specified cell populations from small tissue samples or cultured cells.

The role of desmin and N-cadherin in effusion cytology: a comparative study using established markers of mesothelial and epithelial cells.

The objective of the present study was to analyze the role of the mesothelial markers desmin and N-cadherin in the diagnostic panel of serous effusions. A total of 181 pleural and peritoneal effusions consisted of 101 cases cytologically diagnosed as malignant (89 carcinomas, 12 mesotheliomas), 78 benign, and 2 inconclusive specimens. All specimens were immunostained using 11 antibodies, against epithelial membrane antigen, Ber-EP4, carcinoembryonic antigen, E-cadherin, CA 125, N-cadherin, desmin, calretinin, p53, vimentin, and CD45. After evaluation of immunocytochemistry results, 110 specimens were diagnosed as malignant (98 carcinomas, 12 mesotheliomas) and 71 as benign (56 cellular, 15 paucicellular). The presence of desmin was detected in benign mesothelial cells in 47 of 56 (84%) reactive cellular specimens compared with 1 of 12 (8%) malignant mesotheliomas and 2 of 98 (2%) carcinomas. N-cadherin was expressed in 48 of 56 (86%) reactive cases, 12 of 12 (100%) mesotheliomas, and 47 of 98 (48%) carcinomas. In carcinomas, N-cadherin expression was most often seen in ovarian carcinoma but was also found in other carcinomas. Calretinin, an established marker of mesothelial cells, was detected in 52 of 56 (93%) reactive specimens, 11 of 12 (93%) mesotheliomas, and 3 of 98 (3%) carcinomas. Evaluation of staining results led to reclassification of six malignant specimens as benign, whereas 17 cases diagnosed as benign and the two diagnosed as inconclusive were classified as malignant. In conclusion, desmin appears to be a promising marker for the distinction between reactive mesothelium and malignant epithelial cells in terms of both specificity and sensitivity, and its complementary use with calretinin is recommended. Unlike calretinin, it may also prove valuable for the distinction between benign and malignant mesothelial cells. N-cadherin does not have a role in the distinction between mesothelial and epithelial cells. However, it may prove useful in the characterization of carcinomas of unknown origin. As has previously been shown, a significant number of diagnoses that are based on morphologic examination alone are modified after the use of a broad antibody panel.

Ets-1 mRNA expression in effusions of serous ovarian carcinoma patients is a marker of poor outcome.

Ets-1 proto-oncogene is a transcription factor with a role in the activation of metastasis-associated molecules. We recently found that Ets-1 mRNA expression in solid tumors is a marker of poor prognosis in ovarian carcinoma. The objective of this study was to compare the expression of Ets-1 mRNA in effusions and primary and metastatic tumors of serous ovarian carcinoma patients and to evaluate its prognostic role in effusions. Sections from 67 malignant effusions and 90 primary and metastatic lesions were evaluated for expression of Ets-1 using mRNA in situ hybridization. Expression of Ets-1 mRNA was detected in carcinoma cells in 24 of 67 (36%) effusions. Expression in cancer cells was similar in peritoneal and pleural effusions. In solid lesions Ets-1 expression was detected in both tumor cells and stromal cells in 34 of 90 (38%) lesions. Ets-1 expression in tumor cells showed a strong association with that of stromal cells (p <0.001). Ets-1 expression in effusions showed an association with mRNA expression of basic fibroblast growth factor, previously studied in this patient cohort (p = 0.019). Ets-1 expression in solid lesions showed an association with mRNA expression of vascular endothelial growth factor (p <0.001 for both carcinoma and stromal cells), basic fibroblast growth factor (p = 0.007 for carcinoma cells, p = 0.006 for stromal cells), and interleukin-8 (IL-8) (p = 0.001 for tumor cells). Ets-1 mRNA showed upregulation in metastases when compared with effusion specimens (p = 0.028). In univariate survival analysis Ets-1 expression in carcinoma cells in effusions correlated with poor survival (p = 0.003). Our findings confirm the role of Ets-1 as a novel prognostic marker in advanced-stage ovarian carcinoma and extend it to effusion specimens. The elevated expression in solid metastases supports a central role in tumor progression as well. The association between Ets-1 mRNA expression and the expression of angiogenic genes, documented also in our previous study, points to the close link between these molecules, in agreement with the role of angiogenic genes in the transcriptional activation of Ets-1. The identical phenotype of carcinoma cells in pleural and peritoneal effusions provides further evidence for our theory that cells at these sites share similar genotypic and phenotypic profiles.

Fibrinolysis in grafted arteries and veins.

The fibrinolytic activity in autologous artery and vein grafts was studied in cats during a 4-month period. The fibrinolytic activity in the wall of an aortic segment interposed in the caval vein was increased in comparison to the normal aorta. In the corresponding segment of the caval vein interposed in the aorta, the fibrinolytic activity was reduced during the observation time. Thrombosed segments had a decreased activity. No changes were seen in sham operated animals. The plasminogen activator activity in the vessel wall was found to be influenced by the surrounding milieu.

The effect of various anticoagulant/antiplatelet mixtures on determination of plasminogen activator inhibitor, platelet proteins and hemostasis parameters.

Blood collected in different anticoagulant/antiplatelet agents (ETP, EDTA, citrate, citrate/citric acid pH 4.5 and CTAD) was compared with respect to determination of PAI-1 activity and PAI-1 antigen. beta TG and PF4 were analysed as markers of platelet release. Both the middle layer and the remaining layer of the plasma were studied. Moreover vWF:Ag, FVII:Ag, ECLT, t-PA:Ag, t-PA activity, APTT, VIII:C and VII:C were assayed in blood collected in citrate and CTAD. PAI-1 activity showed the same level in all citrate based anticoagulants and ETP and no increase was found in blood standing for 2 hours at room temperature. On the contrary quick handling was most important for determination of PAI-1 antigen. In tubes anticoagulated with citrate no significant increase was found if the sample was prepared within 1 hour. EDTA was not suitable as anticoagulant mixture. Tubes containing the antiplatelet mixture CTAD could be used for determination of PAI activity, PAI antigen, vWF:Ag, FVII:Ag, t-PA activity and APTT. For measurement of PAI-1 antigen quick handling of blood anticoagulated with antiplatelet mixtures are preferable, and plasma treated in that manner could also be used to assay some hemostasis parameters.

Effect of venous stasis on vessel wall fibrinolysis.

The effects of prolonged venous stasis on release of plasminogen activators (PA) from the caval vein of rats were studied. PA activity was continuously reduced in the intimal layer and after 8 hr of stasis the reduction was statistically significant. After 2 and 3 days no intimal PA activity was found. The PA activity in the adventitial vasa vasorum was unchanged during the experimental period.

Tranexamic acid and gastric fibrinolysis in the rat.

An optimal inhibition of tissue fibrinolysis, studied by a histochemical fibrin slide technique in the rat stomach, was obtained by administration of tranexamic acid in a dose of 60 mg/100 g body weight. A significant fibrinolysis inhibition was found within 5 min, when tranexamic acid in this dose was given either intravenously or intragastrically. A prolonged duration of fibrinolysis inhibition was observed after intragastric administration. After 4 hr no inhibitory effect of tranexamic acid could be recorded, irrespective of the route of administration.

Reduction of gastric haemorrhage by fibrinolysis inhibition - an experimental study in rats.

Gastric ulcerations were induced in rats by pyloric ligature and instillation of 1.0 N HCl. After four hours all rats had developed ulcerations. Increased release of plasminogen activators from the mucosa during these conditions has previously been demonstrated. In the present study we investigated the role of fibrinolysis inhibition versus H2-receptor blockade on the gastric bleeding. Tranexamic acid - a synthetic inhibitor of the fibrinolytic system - was found to significantly (p less than 0.01) reduce blood loss into the gastric juice by 30% measured by 51Cr labelled red blood cells; cimetidine did not reduce the gastric haemorrhage under the experimental conditions used. Both treatment regimes significantly (p less than 0.02) reduced the secretion of gastric juice. These results indicate a contribution of the fibrinolytic system in gastric bleeding from experimentally induced gastric ulcerations.

Localization of tissue fibrinolysis in the gastrointestinal tract.

Tissue fibrinolysis in the stomach and intestine of the rat was studied with a histochemical technique. After perfusion of blood vessels to reduce the influence of circulating plasminogen activator and inhibitor fibrinlysis was localized mainly to submucosal arteries and to the serosa of the gastrointestinal tract. This is opposite to previous observations, in which tissue fibrinolysis in the gastrointestinal tract was suggested to be mainly localized to veins. A method for semiquantitative analysis of tissue fibrolysis in the rat stomach is described.