Clinical Evaluation of Morphology Discrimination: An Algorithm for Rhythm Discrimination in Cardioverter Defibrillators

The aim of this study was to test the new morphology discrimination diagnostic algorithm for ICDs that differentiates supraventricular tachycardias (SVTs) from VTs by analysis of ventricular depolarization complexes morphology. Twenty-five patients implanted with a St. Jude Ventritex single chamber ICD were studied during electrophysiological evaluation at predischarge and were followed for 7 +/- 4 months. Sensitivity and specificity for VT detection and overall diagnostic accuracy of the morphology discrimination algorithm were calculated on 326 detected events. At electrophysiological evaluation, the algorithm was tested during 67 episodes of right atrial pacing, during 119 episodes of RV pacing (at basal interventricular septum and RV apex) and during 27 episodes of sustained AF: specificity was 98%, sensitivity was 66%, and diagnostic accuracy was 80%. All episodes of AF were correctly diagnosed as SVT. Exclusion of detections related to pacing at the basal interventricular septum, resulted in a specificity of 98%, a sensitivity of 85%, and a diagnostic accuracy of 93%. During follow-up, evaluation of the morphology discrimination algorithm on 113 spontaneous episodes (31 VTs, 31 AF, 7 SVTs, and 44 sinus tachycardias) exhibited a specificity of 89%, a sensitivity of 100%, and a diagnostic accuracy of 92%. In conclusion, the morphology discrimination algorithm exhibits a high specificity in discriminating VTs from SVTs, although with a corresponding reduction in sensitivity. The preliminary experience on spontaneous episodes is promising. To correct for the reduction in sensitivity, it is advisable to use this algorithm in parallel with other algorithms for rhythm discrimination (sudden onset, stability) coupled with extended high rate.     

Solid-phase synthesis of the native sequence of horse heart cytochrome c-(66–104)-nonatriacontapeptide and of a C-terminal carboxyamide analog selectively modified at Met-80

The peptide corresponding to the (66–104) sequence of horse heart cytochrome c and its carboxyamide analog, selectively modified at the critical Met⁸⁰ residue, have been synthesized by stepwise solid-phase methods on PAM and BHA resins respectively. The correctness of the growing peptide chain as well as the homogeneity of the final products have been monitored by several analytical methods including quantitative Edman degradation. After HF cleavage both peptides were purified by semipreparative HPLC. The overall yields were 24% for the native (66–104) and 10% for the carboxyamide analog. The homogeneity of the purified synthetic peptides have been determined by different criteria including HPLC, amino acid composition, Edman degradation, electrophoresis, and tryptic peptide mapping. The synthetic fragments have been utilized for preliminary semisynthesis experiments with the native [Hse〉⁶⁵](1–65)H heme-sequence.     

Synthesis and biological activity of carboxyl terminally extended dermorphins

Dermorphinoyl(DMR)-glycine, DMR-sarcosine and DMR-glycyl-arginine have been prepared in order to examine the effect of C-terminal extension of dermorphin (H-Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH₂) on opioid activity. On GPI preparation the addition of Gly, Sar, or Gly-Arg to the carboxyl terminus of dermorphinoic acid was detrimental to μ activity: dermorphinoyl-derivatives, in fact, retain only 5–20% of dermorphin potency. Following intracerebroventricular administration (tail-flick test), whereas the analgesic activities of compounds showed the trend dermorphin >DMR-Sar> DMR-Gly-Arg>DMR-Gly>morphine, the nonapeptide displayed highest activity after subcutaneous injection in mice: DMR-Gly-Arg was 2.5 and 10 times more potent than dermorphin and morphine, respectively.     

Endothelial microparticles induce formation of platelet aggregates via a von Willebrand factor/ristocetin dependent pathway, rendering them resistant to dissociation

Endothelial microparticles (EMP) released from activated or apoptotic endothelial cells (EC) are emerging as useful markers for detection of EC dysfunction. Our recent observation that EMP carry von Willebrand factor (vWf) led us to investigate their interaction with platelets. EMP were incubated with normal washed platelets in the presence or absence of ristocetin, then platelet aggregates were measured by flow cytometry. In the absence of ristocetin, negligible EMP conjugated with platelets (< 5%) but in the presence of ristocetin (1 mg mL(-1)), EMP induced up to 95% of platelets to aggregate. EMP-platelet interaction was 80% blocked by anti-CD42b, or by 0.1 microm filtration to remove EMP. Platelet aggregates induced by normal plasma or high molecular weight vWf (Humate-P) dissociated 50% within 15-25 min following 1:20 dilution. In contrast, aggregates formed with EMP persisted two- to threefold longer with the same treatment, indicating greater stability. A similar degree of prolongation of dissociation was observed using plasma from thrombotic thrombocytopenic purpura (TTP) patients compared with normal plasma. Addition of EMP to plasma from severe von Willebrand disease restored his ristocetin-induced platelet aggregation. Multimer analysis of vWf on EMP showed unusually large vWf (ULvWf). In summary, EMP carries ULvWf multimers, promote platelet aggregates, and increase the stability of the aggregates thus formed.     

Long-term Reproducibility of Response to Noninvasive Programmed Cardiac Stimulation in Spontaneous, Sustained Ventricular Tachycardia Treated with Amiodarone Therapy

A total of 73 noninvasive serial electrophysiological studies were carried out in 12 patients with spontaneous sustained ventricular tachycardia, inducible in spite of chronic treatment with amiodarone, in order to verify the effect of this drug on the long-term reproducibility of the test. A ventricular tachycardia was induced in 72 of 73 times; in 59% of cases, the clinical form was induced. In 8 of 12 patients, two or more types or morphologies of ventricular tachycardia could be induced. The induction modes (driving rate and number of extrastimuli) changed considerably in different studies. During a follow-up of 12 ± 6 months, 5 out of 12 patients had spontaneous relapses. We observed no differences between these patients and the others regarding inducibility, types and morphologies of the induced tachycardias, or induction modes. Therefore, when ventricular tachycardia is inducible in spite of chronic amiodarone therapy, it is always inducible during follow-up, even if a great intrapatient change of type and the morphology of induced tachycardias and induction modes is observed. However, since similar electrophysiological features are present in patients with and without spontaneous recurrence of ventricular tachycardia, serial electrophysiological studies are of little value in predicting the clinical outcome.     

Flow Cytometry and Sizing for Routine Andrological Analysis

Summary: Flow fluorometry and Coulter type sizing analysis of sperm have been applied separately in order to improve human semen analysis. Different methods of sample preparation were evaluated and a protocol involving prestaining pepsin treatment of sperm samples is proposed for fluorometric analysis. The data obtained with fluorometry and sizing analysis result in different kinds of information: Coulter counting allows to automate sperm counting and fluorometry yields more datailled information about normozoospermia and oligozoospermia by determining the proportion of mature spermatozoa and immature germ-cells. These two methods, together with light microscopy, may help to explore the correlation of fertility and pathology of spermatozoa. The aim of these investigations is to yield the preconditions for simultaneous two-parameter analysis of DNA content and cellular size distributions. Zusammenfassung: Durchflußcytophotometrie und Größenmessung für andrologische Routineuntersuchungen von Spermatozoen Durchflußanalyse und Größenanalyse nach dem Coulter-Prinzip wurden angewandt, um die Begutachtung menschlichen Spermas zu verbessern. Unterschiedliche Methoden der Probenaufbereitung wurden ausprobiert, und ein Protokoll mit Pepsinbehandlung der Spermatozoenproben für fluorometrische Analysen wird vorgeschlagen. Die mit der Cytofluorometrie und Größenanalyse erhaltenen Daten ergeben unterschiedliche Informationen: Das Coulter-Prinzip erlaubt die Automatisierung der Spermatozoenzählung, und die Fluorometrie ergibt detailliertere Erkenntnisse über Normozoo-spermie und Oligozoospermie, da die Unterscheidung von reifen Spermatozoen und unreifen Keimzellen ermöglicht wird. Diese beiden Methoden können in Kombination mit der Lichtmikroskopie helfen, die Korrelation zwischen Fertilität und Pathologie von Spermatozoen zu erkunden. Das Ziel dieser Untersuchungen ist es, die Voraussetzungen für gleich-zeitige Zweiparameteranalysen des DNA-Gehaltes und der zellulären Größenverteilungen zu liefern.