High-Density Circumferential Pulmonary Vein Mapping with a 20-Pole Expandable Circular Mapping Catheter

The differentiation of pulmonary vein (PV) electrograms from atrial far-field signals during PV isolation (PVI) for atrial fibrillation (AF) may be difficult. In addition, owing to highly variable PV ostial sizes, current fixed-diameter circular PV mapping catheters may not yield optimal electrograms. We evaluated an expandable, circular 15–25 mm diameter, 20-pole mapping catheter for PV mapping during sustained AF in 25 patients. After selective PV angiography to define the ostial position and size, the catheter was introduced into each PV and withdrawn to the most stable proximal position, with optimal wall contact ensured by progressive loop expansion. At each PV ostium, electrograms recorded at high resolution (HR) were compared with those recorded at a resolution similar to that of a standard 10-pole Lasso catheter. After PVI performed during ongoing AF, the presence of residual far-field potentials (FFP) under both set-ups was compared. We mapped 97 PV, including 4 pairs with common ostia. In the HR recordings, the PV potentials had greater amplitude (0.5 ± 0.1 vs 0.3 ± 0.1 mV, P = 0.001) and fragmentation, whereas left atrial FFP were minimized. After successful isolation of all PV, FFP were observed in 33% of left superior and 28% of left inferior PV on the HR recordings, compared to 66% and 61%, respectively under normal resolution. Catheter stability and optimal wall contact, in combination with HR electrograms can optimize circumferential PV mapping during AF and improve the discrimination of FFP postablation.     

Aza-peptides. III. Experimental structural analysis of aza-alanme and aza-asparagine-containing peptides

To determine the structural perturbations induced by the CαH→Nα exchange in aza-peptides, we have examined by H NMR and IR spectroscopy various derivatives of the aza-analogues of alanine, aspartic acid and asparagine in different organic solvents with increasing polarity. Their general formulas are: R'-AzXaa-NR²R³, R'-Pro-AzXaa-NR²R³ and R-AzXaa-Pro-NR²R³ (where AzXaa denotes the aza-analogue of the amino acid residue Xaa = Ala, Asp, Asn; R = Boc, Z; R², R³= H, Me, iPr). The aza-analogue of an amino acid residue appears to be a strong p-turn-inducing motif, and the AzAsn carboxamide side-chain is capable of interacting, as a proton donor, with the preceding peptide carbonyl group.     

Structural variations in the crystal structures of two homologous DL-Leu and Δ-Leu containing peptides+

The similar conformations and interaction modes of Ac-DL-Leu-Nme₂ and Ac-Δ-Leu-NMe₂ molecules in the solid state allow the comparison of their geometrical parameters. The most evident variations are essentially restricted to the α,β-unsaturated side-chain which adopts the Z-disposition. The dimensions of the peptide backbone are much less sensitive to α,β-unsaturation, with a small shortening by 0.04 Å and 0.02 Å of the N-C^α and C^α-C′ bonds, respectively, and an increase by 6° of the N-C^α- C′ bond angle. The ethylenic and amide groups in the Δ-Leu derivative are far from coplanarity, and a significant electronic conjugation of the π-orbital is likely to be rejected.     

New regimen for interpleural block in children

A new regimen for postoperative analgesia after thoracic surgery is proposed. Eight children received an interpleural infusion using bupivacaine 0.1% in a regimen from 0.5 ml·kg^?1·h^?1 up to 1 ml·kg^?1·h^?1, for 48 h according to the pain scores. The plasma levels after 24 h and 48 h were measured as well as the pleural level and in two patients the free fraction of plasma bupivacaine and the plasma PPX (a metabolite of bupivacaine) and one patient the orosomucoid (main plasma protein involved in bupivacaine protein binding) were also measured pre and postoperatively. The results shows the safety of such a regimen, for two days of postoperative analgesia.     

Age-Dependent Prevalence of Cardioembolic Sources Detected by TEE: Diagnostic and Therapeutic Implications

To define the prevalence of cardioembolic sources found by transesophageal echocardiography (TEE) in different age groups of patients with and without cryptogenic systemic embolism, TEE risk factors for cardiogenic embolism were identified from 341 consecutive patients referred for TEE. One hundred and thirty-five had cryptogenic cerebral or systemic peripheral embolic events (CEE) and 206 other indications for TEE (CTR). Cardioembolic sources were found in 40% of CEE and in 29% of CTR (P < 0.02). Specifically, left atrial (LA) thrombi (P < 0.0001), atrial septal aneurysm with right-to-left shunt (P < 0.002), and atherosclerotic aortic plaques (P < 0.02) were more frequent. The prevalence of potential cardioembolic sources was significantly higher in patients ≥ 70-years old than in younger patients (P < 0.03), specifically LA thrombi (P < 0.004) and atherosclerotic aortic plaques (P < 0.0001). In patients ≥ 70-years old, potential cardioembolic sources were found in 63% and in 40% in CEE and CTR (P = 0.073), respectively. However, LA thrombi were more frequent in CEE (P < 0.003). Thus, potential cardioembolic sources observed by TEE are found more frequently in patients ≥ 70-years old than in younger patients. LA thrombi were more frequent in CEE than in CTR patients ≥ 70-years old. In patients ≥ 70-years old with CEE who are eligible for an anticoagulant regimen, a search for potential cardioembolic sources by TEE should be considered.     

Determination of the ratios of the aromatic amino acid residues by first- or second-derivative UV spectrometry for a simple characterization of peptides

A method for the simultaneous determination of the ratios of the three aromatic amino-acid residues in peptides was set up in acidic conditions. Binary and ternary mixtures of these amino acids were prepared, and first- and second-derivative spectra then calculated from their 0.1 nm resolution spectra between 240 and 320 nm. Certain spectral bands were chosen to differentiate tyrosine from tryptophan on the first-derivative spectra, and phenylalanine from tyrosine and tryptophan on the second-derivative spectra. Variation of the amplitude of the chosen bands was shown to be a linear function of the ratio of the aromatic amino acids in the mixture. This technique was validated with peptides whose sequence was known. The difference between theoretical and experimentally determined ratios was lower than 10%. Since the results are obtained as ratios, neither the concentration nor the nature of the peptide has to be known. The feasibility of application using a photodiode array detector with high resolution in reversed-phase high-performance liquid chromatography is discussed. © Munksgaard 1995.     

A Subset of Patients With Recurrent Spontaneous Abortion Is Deficient in Transforming Growth Factor β-2-Producing “Suppressor Cells” in Uterine Tissue Near the Placental Attachment Site

PROBLEM : To determine if patients with unexplained recurrent miscarriage have a deficiency of decidual immunosuppressor cells that produce transforming growth factor β type 2, as has been found in mice with abortion due to rejection and/or trophoblast failure. METHODS : Decidual biopsy specimens were taken as near to the placental attachment site as possible under ultrasound guidance from first trimester legal termination (control) patients with recurrent miscarriage and non-viable pregnancy, and from patients with sporadic missed abortion. The tissue was tested for TGFβ-2⁺ suppressor cells by in situ hybridization, immunohistochemistry, and analysis of supernatants. RESULTS : TGFβ-2-related suppressor molecules similar but not identical to those identified in pregnant mice were released by decidual lymphoid cells. Fifty percent of 14 recurrent miscarriage patients showed a lack of suppressor cells and 59% were subnormal in comparison to 20 controls and 5 sporadic miscarriage patients, where 80–85% of the patients had detectable suppressor cells. CONCLUSIONS : Suppressor cell deficiency is compatible with a role for rejection and/or trophoblast failure in some patients with recurrent miscarriage. Presence of suppressor cells in most patients with missed abortion (4/5) is compatible with an alternative cause of fetal death, similar to findings reported in genetic fetal death mice.     

CONTINUOUS I.V. INFUSION OF LABETALOL FOR POSTOPERATIVE HYPERTENSION: Haemodynamic Effects and Plasma Kinetics

Labetalol is a combined -and ß-adrenoreceptor blockingagent. A loading dose may be used to antagonize sympatheticoveractivity rapidly after surgery and be followed by a continuousinfusion to achieve a stable effect. The haemodynamic effectsand pharmacokinetics of this method of labetalol administrationwere studied in six rewarmed, extubated and sedated patients15±2 h after aortobifemoral bypass surgery. Patientswere monitored with radial and thermistor-tipped pulmonary arterycatheters. Labetalol 1.5 mg kg^–1 was injected i.v. over5 min and a maintenance infusion of 0.2 mg kg ^–1 h^–1was started 30 min later and continued for 5.5 h. Within 5 minof the loading dose, i.v. labetalol induced significant (P <0.05) decreases in mean arterial pressure (–32 ±11%),in heart rate (–20±11%) and in cardiac index (–26± 15%) that lasted throughout the infusion. Changes insystemic vascular resistance were not uniform, but an increasewas not observed in any patient. Mean stroke volume index andventricular filling pressures were not significantly affectedby labetalol administration. The mean measured steady stateplasma concentration (C^ss) (264 ±46 ng ml^–1) washigher than predicted (170 ng ml^–1) because the clearance(13.1 ±2.4 ml kg^–1 min^–1) was lower thanthat used to calculate the infusion rate. We conclude that labetalolis an effective antihypertensive agent in the postoperativeperiod. A C^ss can be achieved rapidly by such i.v. administrationand this offers the advantage of inducing rapid and stable haemodynamiceffects. However, calculation of the infusion rate must be basedon a clearance of 13 ml kg^–1 min^–1.     

VJ REARRANGEMENTS OF THE TCRγ LOCUS IN PERIPHERAL T-CELL LYMPHOMAS: ANALYSIS BY POLYMERASE CHAIN REACTION AND DENATURING GRADIENT GEL ELECTROPHORESIS

Using Southern blotting for the diagnosis of clonality in peripheral T-cell lymphomas (PTCLs), analysis of the T-cell receptor (TCR) γ gene rearrangement was shown to be more informative than that of the TCR β gene rearrangement. In order to amplify every VJγ rearrangement, a polymerase chain reaction (PCR) procedure using newly designed GC-clamp primers has been developed. All primers can be mixed in a single multiplex PCR. PCR products are analysed by denaturing gradient gel electrophoresis (DGGE), providing tumour-specific imprints inasmuch as the procedure characterizes N sequence polymorphism at the VJ junctions. In a series of 30 PTCL cases, the PCR procedure demonstrated 27 cases to be clonally rearranged and failed in three cases. PCR was more accurate than Southern blotting, showing 47 rearranged γ alleles, four of which were undetectable on the Southern blot. When lymphomas were studied at different sites and at relapse, the DGGE pattern remained unchanged. In PTCL, the proposed PCR is helpful for the diagnosis and staging of the disease and should improve the follow-up monitoring. The undetectability of clonal rearrangements in a few cases is discussed in the light of concepts of lymphomagenesis and T-cell differentiation.