Inhibition of Desmoteplase-Induced Fibrinolytic Activity In Vitro

Introduction. Laboratory monitoring of the hemostatic system during thrombolytic therapy requires that the fibrinolytic activity generated in vivo be immediately inhibited at blood collection in order to prevent artificial results as a consequence of degradation of clotting proteins. For most thrombolytic drugs efficient inhibitors have been described, but not yet for the new thrombolytic agent, desmoteplase, which is vampire bat salivary plasminogen activator. Therefore, we investigated the effect of aprotinin and D-Phe-Pro-Arg-chloromethylketone (PPACK) on desmoteplase-induced fibrinolysis.Materials and methods. We added desmoteplase in pharmacological concentrations to blood samples supplemented with aprotinin, PPACK or both. Fibrinolytic activity was assessed by measuring degradation products of fibrin and fibrinogen, plasmin-antiplasmin complex, thrombin-antithrombin complex, fibrinogen and some overall clotting assays.Results. Desmoteplase caused in vitro activation of plasminogen with concomitant degradation of fibrin and fibrinogen. Aprotinin completely inhibited these effects, whereas PPACK gave only partial inhibition. Neither inhibitor prevented plasminogen activation and thus significant generation of plasmin-antiplasmin complex was observed.Conclusion. Blood collection for hemostatic analyses in clinical studies with desmoteplase requires addition of aprotinin (final concentration 250 KIU/mL) in order to prevent in vitro artifacts.     

Clinical performance of a ventricular automatic capture verification algorithm

BACKGROUND: This study was conducted to evaluate the clinical performance of the ventricular automatic capture feature as implemented in the Insignia I Ultra pacemaker system (Guidant) utilizing a variety of ventricular leads. Currently, the optimal programming of the pacemaker output considers both pacemaker efficiency (prolonging battery longevity) and patient safety (adequate safety margin). The ability of a pacemaker to automatically adjust the ventricular output above the pacing threshold while maintaining the appropriate safety margin has been explored since the early 1970s and is only available today in conjunction with a specific low polarization lead system. METHODS: One hundred and five patients were enrolled from 17 European centers utilizing 31 different types of ventricular leads were followed through their 3-month follow-up visit. There were no restrictions on the type of ventricular leads used. RESULTS: The average mean difference between the commanded autothreshold test (0.652 + 0.335 V) and the manual threshold test (0.651 + 0.335 V) was 0.001 + 0.49 (P < 0.0001). The average mean difference between the ambulatory autothreshold test (0.696 + 0.322 V) and the commanded autothreshold test (0.682 + 0.315 V) was 0.002 + 0.74 (P < 0.0001). Holter recordings confirmed that there were no loss of capture incidences without a backup pulse being delivered. In addition, the mean number of backup pulses delivered in a 24-hour period was less than 0.1% of the total number of paced beats. CONCLUSIONS: This study provided that the automatic capture feature while using a variety of leads accurately determines the ventricular stimulation threshold and safely delivers a backup pulse when required.     

Back to basics in diagnosing diabetic polyneuropathy with the tuning fork!

OBJECTIVE: Several national and international scoring systems are used to diagnose diabetic polyneuropathy (PNP). The variety in these scores and the lack of data on validity and predictive value has led to a comparison and validation of the scores with clinical standards for PNP to determine the most powerful measurement for screening. RESEARCH DESIGN AND METHODS: Three matched groups were selected: 24 diabetic patients with neuropathic foot ulcers, 24 diabetic patients without PNP or ulcers, and 21 control subjects without diabetes. In all participants the scores from the International Consensus on the Diabetic Foot (ICDF) and the Dutch Nederlandse Diabetes Federatie-Centraal Beleids Orgaan (NDF/CBO) were tested. The Diabetic Neuropathy Symptom score, the Diabetic Neuropathy Examination score, Heart Rate Variability, the Nerve Conduction Sum score, and a San Antonio Consensus sum score were obtained as clinical standards. Reproducibility was tested in a separate study (13 patients). RESULTS: The construct validity and discriminative power of the ICDF and NDF/CBO scores were comparable, although monofilaments (NDF/CBO) scored lower. The predictive value was good for all scores, with the best results being obtained for the tuning fork (NDF/CBO). Reproducibility of the NDF/CBO scores (monofilaments and tuning fork) was high. CONCLUSIONS: The characteristics of the scores of tests recommended by ICDF and NDF/CBO are comparable. The single use of the 128-Hz tuning fork produces results similar to the extended scores of the ICDF and much better than those of monofilaments on validation and for predictive value. For screening we therefore advise the use of the tuning fork alone.     

Dynamic protein expression patterns during intraoral wound healing in the rat

Wound healing after cleft palate surgery is often associated with impairment of maxillary growth and dento-alveolar development. Wound contraction and scar tissue formation contribute strongly to these effects. In vitro studies have revealed that fibroblasts isolated during different phases of palatal wound healing show phenotypical differences. They change from a quiescent to an activated state and then partly back to a quiescent state. In this study, we evaluated the existence of fibroblast phenotypes at several time-points during palatal wound healing in the rat. Based on cytoskeletal changes (alpha-sma, vimentin, vinculin), integrin expression (alpha1, alpha2, alpha(v) and beta1) and changes in cellularity, we conclude that phenotypically different fibroblast populations are also present during in vivo wound healing. Alpha-sma and the integrin subunits alpha1 and alpha(v) were significantly up-regulated, and vinculin was significantly down-regulated, at early time-points compared to late time-points in wound healing. These changes point to an activated fibroblast state early in wound healing. Later in wound healing, these activated fibroblasts return only partially to the unwounded situation. These results strongly support the idea that different fibroblast populations with specific phenotypes occur in the course of palatal wound healing.     

Smoking Impairs Rectal Mucosal Bloodflow—A Pilot Study: Possible Implications for Transanal Advancement Flap Repair

ABSTRACT Transanal advancement flap repair has been advocated as the treatment of choice for transsphincteric perianal fistulas, because it enables the healing of almost all fistulas without sphincter damage and consequent continence disturbance. After initial promising reports, recently less favorable results have been reported. It remains unclear why there is such a large variety in the reported healing rates. Recently, it has been suggested that impaired wound healing caused by a diminished rectal mucosal perfusion in patients who smoke may lead to the breakdown of the advancement flap in patients undergoing flap repair for perianal fistulas. This study was designed to investigate the difference in blood flow in rectal mucosa between patients who smoke and those who do not smoke. Furthermore, we assessed the impact of the creation of a mucosa advancement flap and the difference in blood flow in the flap between smoking and nonsmoking patients. Between July 2001 and July 2002, 23 consecutive patients (19 males; median age, 46 (range, 26–69) years) with a perianal fistula of cryptoglandular origin underwent surgery for a perianal fistula. Among them were 13 patients who smoked cigarettes. All patients underwent intraoperative laser Doppler flowmetry. Median blood flow before transanal advancement flap repair was 35 (range, 8–70) volts in patients who did not smoke. In patients who smoked the median blood flow before transanal advancement flap repair was 18 (range, 7–35) volts. Blood flow was significantly lower in patients who smoked (P = 0.018; Mann-Whitney). In conclusion, it seems likely that impaired wound healing caused by a diminished rectal mucosal perfusion is a contributing factor in the breakdown of advancement flaps in patients who smoke cigarettes.Read at the meeting of The American Society of Colon and Rectal Surgeons, New Orleans, Louisiana, June 21 to 26, 2003.Reprints are not available.     

The origin of extrinsic nitrergic axons supplying the human eye

Nitrergic nerve fibres of intrinsic and extrinsic origin constitute an important component of the autonomic innervation in the human eye. The intrinsic source of nitrergic nerves are the ganglion cells in choroid and ciliary muscle. In order to obtain more information on the origin of extrinsic nitrergic nerves in the human eye, we obtained superior cervical, ciliary, pterygopalatine and trigeminal ganglia from six human donors, and stained them for neuronal nitric oxide synthase (nNOS) and nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-D). In the superior cervical ganglia, nNOS/NADPH-D-positive varicose axons were observed whereas perikarya were consistently negative. Fewer than 1% of perikarya in the ciliary ganglia were labelled for nNOS/NADPH-D. The diameter of nNOS/NADPH-D-positive ciliary perikarya was between 8 and 10 microm, which was markedly smaller than the diameter of the vast majority of negative perikarya in the ciliary ganglion. More than 70% of perikarya in the pterygopalatine ganglia were intensely labelled for both nNOS and NADPH-D. In trigeminal ganglia, 18% of perikarya were nNOS/NADPH-D-positive. The average diameter of trigeminal nNOS/NADPH-D perikarya was between 25 and 45 microm. Pterygopalatine and trigeminal ganglia are the most likely sources for extrinsic nerve fibres to the human eye.     

After major ABO-mismatched allogeneic hematopoietic progenitor cell transplantation, erythroid engraftment occurs later in patients with donor blood group A than donor blood group B

BACKGROUND: Isohemagglutinins directed against the donor blood group frequently delay erythroid engraftment after major ABO-mismatched allogeneic hematopoietic progenitor cell transplantation (HPCT). Graft-versus-host reactions are capable of accelerating the clearance of isohemagglutinins. Whether immunogenicity of the A- and B-antigen is important in this process is unknown. PATIENTS AND METHODS: Data of 807 patients from three centers were screened for patients with major or bidirectionally ABO-mismatched donors. Clinical data and red blood cell (RBC) transfusion support were analyzed retrospectively. RESULTS: A total of 158 patients with major or bidirectionally mismatched donors were identified. After major mismatched HPCT, patients with anti-A directed against the donor blood group required RBC transfusion support for a median of 109 days (range, 0-324 days) compared to 21 days (range, 2-98 days) for patients with anti-B directed against donor blood group (log-rank test, p = 0.0001). Other risk factors associated with prolonged RBC transfusion support in univariate analysis were age (p = 0.024), cytomegalovirus infection (p = 0.016), hemolytic anemia (p = 0.027), and chronic bleeding disorders (p = 0.038). The independent influence of donor blood group and recipient age were confirmed in a multivariate analysis. CONCLUSION: These results indicate that the immunogenicity of the ABO antigen plays an important role for the kinetics of erythroid engraftment after ABO-mismatched HPCT.