SOLID-PHASE PEPTIDE SYNTHESIS OF SOMATOSTATIN USING MILD BASE CLEAVAGE OF Nα-9- FLUORENYLMETHYLOXYCARBONYLAMINO ACIDS

Experimental details for the “Fmoc solid phase peptide synthesis” of somatostatin are described. The 9-fluorenylmethyloxycarbonyl group was rapidly and quantitatively cleaved by 55% piperidine in dimethylformamide and monitored (u.v.) manually. For a kinetic study, a centrifugal reactor with a photometric control system and reference cell was used at each stage. The symmetrical anhydride coupling reaction was rapid and either acetic anhydride or fluorescamine termination was incorporated to minimize formation of deletion peptides. Anchor-bond cleavage was effected with trifluoroacetic acid which simultaneously removed all the acid labile tert.-butyl side chain protecting groups. Nα-9-fluorenylmethyloxycarbonyl peptides may be obtained by omitting the piperidine deprotection step after the last cycle of synthesis. From several syntheses, analytically pure di-S-protected somatostatin 14-peptide was obtained in 55–60% overall yield. The S-protecting groups were removed and the product was purified by gel filtration to give homogeneous dihydrosomatostatin (91% yield). Oxidation of dihydrosomatostatin with potassium ferricyanide and purification by countercurrent distribution provided analytically pure homogeneous somatostatin.     

Excess cumulative blood flow and repayment during reactive hyperemia in human cutaneous tissue

The influence of duration of vascular occlusion upon the reactive hyperemic response in human cutaneous tissue was studied in 6 subjects. Blood flow in cutaneous tissue was measured dorsally on the distal phalanx of the second finger by the local ¹³³Xenon washout technique. Post-occlusive blood flow, calculated from the steepest part of the ¹³³Xenon washout curve just after release of vascular occlusion, reached a maximum value when duration of vascular occlusion was 12 min. However, excess cumulative blood flow, i.e. the integrated blood flow during reactive hyperemia minus integrated pre-ischemic blood flow for a period corresponding to the duration of the reactive hyperemic response, increased with increasing duration of vascular occlusion from 3 to 24 min. Fractional repayment, i.e. excess cumulative blood flow divided by pre-ischemic blood flow times duration of vascular occlusion, was not correlated significantly to duration of vascular occlusion. However, there was a significant inverse correlation between fractional repayment and pre-occlusive blood flow, indicating that, besides metabolic factors, pre-ischemic blood flow in cutaneous tissue is influenced by other factors, such as heat regulation.     

E-SELECTIN EXPRESSION IN EXPERIMENTAL MODELS OF INFLAMMATION IN MICE

E-selectin (CD62E, formerly termed ELAM-1) is a cytokine-inducible adhesion molecule which mediates the binding of neutrophils, monocytes, and skin homing T-cells. The murine homologue of E-selectin has been cloned. A monoclonal antibody (21KC10) was used here to study immunohistochemically the expression and regulation of murine E-selectin in vitro and in vivo . As described for the human system, there was no staining of normal endothelium in skin and other tissues. LPS and tumour necrosis factor-alpha (TNF-α ), but not interleukin-4 (IL-4) or interferon-gamma (IFN- γ), induced a transient expression of E-selectin, both when injected in vivo and when added to endothelial cell lines in vitro. To analyse temporal expression of E-selectin under pathophysiological conditions in vivo, we chose two murine models of inflammation: allergic (ACD) and irritant contact dermatitis (ICD). Expression of E-selectin was found to be induced on vascular endothelium of post-capillary venules in both ACD and ICD. In ICD, maximal staining of endothelial cells occurred earlier than in ACD. Expression of E-selectin during ICD and ACD was then compared between strains of mice which differ with regard to the intensity of their inflammatory reaction. BALB/c mice, which in contrast to C57BI/6 mice show a denser infiltrate and prolonged influx of granulocytes and monocytes, revealed a more pronounced and more prolonged expression of E-selectin than C57BI/6 mice. This held true for both ACD and ICD, and in each case, peak expression of E-selectin was associated with the highest density of the leukocytic infiltrate. This study thus reveals regulatory mechanisms involved in the expression of murine E-selectin in vivo and in vitro . It also demonstrates a correlation between endothelial expression of E-selectin and the genetically determined intensity of the inflammatory response.     

Pre‐operative fasting: a nationwide survey of German anaesthesia departments

Background: Shorter pre‐operative fasting improves clinical outcome without an increased risk. Since October 2004, German Anaesthesiology Societies have officially recommended a fast of 2 h for clear fluids and 6 h for solid food before elective surgery. We conducted a nationwide survey to evaluate the current clinical practice in Germany. Methods: Between July 2006 and January 2007, standardized questionnaires were mailed to 3751 Anaesthesiology Society members in leading positions requesting anonymous response. Results: The overall response rate was 66% (n=2418). Of those, 2148 (92%) claimed familiarity with the new guidelines. About a third (n=806, 34%) reported full adherence to the new recommendations, whereas 1043 (45%) reported an eased fasting practice. Traditional Nil per os after midnight was still recommended by 157 (7%). Commonest reasons reported for adopting the new guidelines were: ‘improved pre‐operative comfort’ (84%), and ‘increased patient satisfaction’ (83%); reasons against were: ‘low flexibility in operation room management’ (19%), and ‘increased risk of aspiration’ (13%). Conclusion: Despite the apparent understanding of the benefits from reduced pre‐operative fasting, full implementation of the guidelines remains poor in German anaesthesiology departments.     

Electrical Performance and Automatic Capture Characteristics of a 3.5-mm2 Passive Fixation Lead during 1-Year Follow-Up

Background: Bipolar low polarization electrodes are recommended for a regular AutoCapture™ (St. Jude Medical, Inc., Sylmar, CA, USA) function in order to effectively detect the evoked response (ER) signal. The objective of this national multicenter registry was to evaluate the electrical performance and the AutoCapture™ characteristics of the bipolar ventricular pacing lead IsoFlex S, model 1636T or 1646T (St. Jude Medical), in combination with single- and dual-chamber pacemakers.
Methods: Ventricular pacing and sensing thresholds, lead impedance, ER amplitude, and polarization signals were measured at discharge and routine follow-up visits after 1, 3, 6, 9, and 12 months. AutoCapture™ activation was recommended based on the results of the ER sensitivity test.
Results: Of the 252 patients initially included, 109 (43%) have completed the follow-up. The mean ventricular pacing threshold was 0.43 ± 0.19 V at discharge and 0.68 ± 0.32 V at 12 months postimplant. The values for the ventricular sensing threshold were between 9.51 ± 4.12 and 9.99 ± 4.09 mV at discharge and at the 12-month follow-up. The unipolar lead impedance decreased from 533 ± 94 to 476 ± 73 ohms during the follow-up. The mean ER amplitude was 16.47 ± 6.70 mV at discharge and 17.42 ± 7.43 mV after 12 months, and the corresponding mean polarization signals were 0.59 ± 1.00 and 0.74 ± 1.24 mV, respectively. AutoCapture™ activation was recommended in at least 95% of the patients investigated over the 12-month follow-up.
Conclusion: The bipolar ventricular pacing lead IsoFlex S 1636/1646T shows a good electrical performance and is mostly compatible with the AutoCapture™ algorithm.