Non-anticoagulant heparin increases endothelial nitric oxide synthase activity: role of inhibitory guanine nucleotide proteins

Heparin, which is widely used clinically, has recently been shown to have specific properties affecting the vascular endothelium. We hypothesized that heparin stimulates endothelial nitric oxide synthase (eNOS) activity by a mechanism independent of its anticoagulant properties and dependent on an inhibitory guanine nucleotide regulatory protein (Gi). We determined the effect of both heparin and N-acetyl heparin (Non-Hep), a heparin derivative without anticoagulant properties, on eNOS activity in cultured bovine aortic endothelial cells and on endothelium-dependent relaxation in isolated vascular rings. The eNOS activity was determined by measuring both citrulline and nitric oxide (NO) metabolite formation. Heparin and Non-Hep dose-dependently increased basal eNOS activity (ED50 1.0 microgram/ml or 0.15 U/ml), an effect that was significantly inhibited by pertussis toxin (100 ng/ml), a Gi-protein inhibitor. Agonist-stimulated (acetylcholine, 10 microM) eNOS activity was potentiated following pre-treatment with both heparin and Non-Hep and reversed by pertussis toxin. Heparin and Non-Hep induced a dose-dependent relaxation in preconstricted thoracic aortic rings, an effect that was significantly inhibited by pertussis toxin, endothelial inactivation (following treatment with sodium deoxycholate) and NG-nitro-L-arginine-methyl ester (L-NAME). We conclude that heparin and non-anticoagulant heparin induce endothelium-dependent relaxation following activation of eNOS by a mechanism involving a Gi-protein. Administration of heparin derivatives without anticoagulant properties may have therapeutic implications for the preservation of eNOS in conditions characterized by endothelial dysfunction.     

Survival of Taenia solium cysticerci in carcasses of pigs kept at 4 C

In the present study, the survival of cysticerci of Taenia solium in carcasses of 1 Small-Ear-Miniature and 2 Landrace Small-Ear-Miniature pigs kept in a refrigerator at 4 C was determined. The viability of the cysticerci was determined by observing evagination and active movement of the scolex under a fluorescent light after digestion in pig bile. Although no viable cysticerci were found after day 30, 58.8% cysticerci survived between day 26 and day 30. Moreover, more than 80% of the cysticerci were viable between day 1 and day 25. These findings indicate that taeniasis solium can be transmitted through eating raw or undercooked pork or viscera of pigs following refrigeration at 4 C for less than 30 days.     

Oxidative damage to sarcoplasmic reticulum Ca2+-ATPase AT submicromolar iron concentrations: evidence for metal-catalyzed oxidation

The sarcoplasmic reticulum (SR) calcium ATPase carries out active Ca2+ pumping at the expense of ATP hydrolysis. We have previously described the inhibition of SR ATPase by oxidative stress induced by the Fenton reaction (Fe2+ + H2O2 --> HO. + HO- + Fe3+). Inhibition was not related to peroxidation of the SR membrane nor to oxidation of ATPase thiols, and involved fragmentation of the ATPase polypeptide chain. The present study aims at further characterizing the mechanism of inhibition of the Ca2+-ATPase by oxygen reactive species at Fe2+ concentrations possibly found in pathological conditions of iron overload. ATP hydrolysis by SR vesicles was inhibited in a dose-dependent manner by micromolar concentrations of Fe2+, H2O2, and ascorbate. Measuring the rate constants of inactivation (k inact) at different Fe2+ concentrations in the presence of saturating concentrations of H2O2 and ascorbate (100 microM each) revealed a saturation profile with half-maximal inactivation rate at ca. 2 microM Fe2+. Inhibition was not affected by addition of 200 microM Ca2+ to the medium, indicating that it was not related to iron binding to the high affinity Ca2+ binding sites in the ATPase. Furthermore, inhibition was not prevented by the water-soluble hydroxyl radical scavengers mannitol or dimethylsulfoxide, nor by butylated hydroxytoluene (a lipid peroxidation blocker) or dithiothreitol (DTT). However, when Cu2+ was used instead of Fe2+ in the Fenton reaction, ATPase inhibition could be prevented by DTT. We propose that functional impairment of the Ca2+-pump may be related to oxidative protein fragmentation mediated by site-specific Fe2+ binding at submicromolar or low micromolar concentrations, which may occur in pathological conditions of iron overload.     

Cluster analysis of consensus water sites in thrombin and trypsin shows conservation between serine proteases and contributions to ligand specificity

Postischemic injury in recipients of 3-7-d-old renal allografts was classified into sustained (n = 19) or recovering (n = 20) acute renal failure (ARF) according to the prevailing inulin clearance. Recipients of optimally functioning, long-standing allografts and living donors undergoing nephrectomy served as functional (n = 14) and structural controls (n = 10), respectively. Marked elevation above control of fractional clearance of dextrans of graded size was consistent with transtubular backleak of 57% of filtrate (inulin) in sustained ARF. No backleak was detected in recovering ARF. To explore a structural basis for backleak, allograft biopsies were taken intraoperatively, 1 h after reperfusion in all recipients, and again on day 7 after transplant in a subset (n = 10). Electron microscopy revealed disruption of both apical and basolateral membranes of proximal tubule cells in both sustained and recovering ARF, but cell exfoliation and tubule basement membrane denudation were negligible. Histochemical analysis of membrane-associated adhesion complexes confirmed an abnormality of proximal but not distal tubule cells, marked in sustained ARF but not in recovering ARF. Staining for the zonula occludens complex (ZO-1) and adherens complex (alpha, beta, and gamma catenins) revealed diminished intensity and redistribution of each cytoskeletal protein from the apico-lateral membrane boundary. We conclude that impaired integrity of tight junctions and cell-cell adhesion in the proximal tubule provides a paracellular pathway through which filtrate leaks back in sustained allograft ARF.     

Tendon interposition in a juxta-epiphyseal fracture of the proximal phalanx

PURPOSE: To report the clinicopathologic features of intraocular osseous production in association with proliferative vitreoretinopathy. METHOD: The clinical and histopathologic features of two patients with proliferative vitreoretinopathy and intraocular bone formation are reviewed. RESULTS: Preretinal osseous tissue incorporated in the proliferative vitreoretinopathy was surgically removed in one patient, and osseous tissue was present in the proliferative vitreoretinopathy in the enucleated eye of the other patient. CONCLUSIONS: Bone formation, presumably from metaplastic retinal pigment epithelium, may be present in proliferative vitreoretinopathy tissue. The intraocular bone is present internal rather than external to the neurosensory retina.     

Cancer genetics, cytogenetics--defining the enemy within

BACKGROUND/AIMS: International comparisons of clinical practice may help in assessing the magnitude and possible causes of variation in cross national healthcare utilisation. With this aim, the indications for cataract surgery in the United States, Denmark, the province of Manitoba (Canada), and the city of Barcelona (Spain) were compared. METHODS: In a prospective multicentre study, patients scheduled for first eye cataract surgery and aged 50 years or older were enrolled consecutively. From the United States 766 patients were enrolled; from Denmark 291; from Manitoba 152; and from Barcelona 200. Indication for surgery was measured as preoperative visual status of patients enlisted for cataract surgery. Main variables were preoperative visual acuity in operative eye, the VF-14 score (an index of functional impairment in patients with cataract) and ocular comorbidity. RESULTS: Mean visual acuity were 0.23 (USA), 0.17 (Denmark), 0.15 (Manitoba), and 0.07 (Barcelona) (p < 0.001). When restricting the sample to eyes with normal retina and macula, no significant difference between United States and Denmark was observed (p > 0.05). Mean VF-14 scores were 76 (USA), 76 (Denmark), 71 (Manitoba), and 64 (Barcelona) (p < 0.001). CONCLUSION: Similar indications for cataract surgery were found in the United States and Denmark. Significantly more restricted indications were observed in Manitoba and Barcelona. Possible explanations for the results are discussed, including differences in sociodemographic characteristics, access to care, surgeons' willingness to operate, and patient demand.     

Allelotype analysis of uterine leiomyoma: localization of a potential tumor suppressor gene to a 4-cM region of chromosome 7q

The degree and nature of patient involvement in consultations with health professionals influences problem and needs recognition and management, and public accountability. This paper suggests a framework for understanding the scope for patient involvement in such consultations. Patients are defined as co-producers of formal health services, whose potential for involvement in consultations depends on their personal rights, responsibilities and preferences. Patients' rights in consultations are poorly defined and, in the National Health Service (NHS), not legally enforceable. The responsibilities of patients are also undefined. I suggest that these are not to deny, of their own volition, the rights of others, which in consultations necessitate mutuality of involvement through information-exchange and shared decision-making. Preferences should be met insofar as they do not militate against responsibilities and rights.