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 After selective PV angiography to define the ostial position and size, the catheter was introduced into each PV and withdrawn to the most stable proximal position, with optimal wall contact ensured by progressive loop expansion.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.     

Common Health Problems among Minority Elders

This article reviews the primary health problems of African-American, Hispanic-American, Asian/Pacific Islander-American, and Native-American elders. The goal is to familiarize practicing dietitians with the differences in longevity, disease spectrum, and functional status (where data are available) for each of these ethnic groups. These data should be of assistance in making decisions regarding dietary counseling for ethnic elders. It is acknowledged that most data accumulated according to race do not accurately measure ethnicity. The degree of acculturation may vary widely among individuals. Therefore, it is recommended that dietitians solicit clients’ perceptions of the factors that may contribute to illness and the barriers to implementing recommended remedies.     

Relation Between Cycle Length, Volume, and Pressure in Type I Atrial Flutter

Assuming that type I atrial flutter is a macroreentrant circuit, its cycle length should vary with the atrial dimensions. In order to test this hypothesis, flutter cycle length was measured while inducing atrial volume and pressure changes by postural and pharmacological means in seven patients undergoing a therapeutic programmed stimulation for type 1 atrial flutter conversion. Right atrial volume was estimated from B-mode echocardiography data. Basal values were compared with those obtained during inspiration, expiration, Valsalva maneuver, negative tilt (head down), and positive tilt (head up) with 0.8–1.6 mg p.o. nitroglycerin. The right atrial size increased slightly from 17.8 to 18.3 cm² (P = 0.04) during the pressure load induced by negative tilt (+ 3 mmHg), with a corresponding lengthening of the flutter cycle length from 228 to 233 msec (P = 0.02). Similarly, pressure unloading of -2 mmHg by positive tilting and nitrates was accompanied by a decrease in right atrial size to 16.6 cm² (P = 0.04), with a corresponding decrease in cycle length from 228 to 219 msec (P = 0.03). Respiratory maneuver yielded similar results with an inspiratory cycle lengthening, expiratory shortening, and further shortening during Valsalva maneuver. These experiments demonstrate a direct relation between cycle length and atrial volume in human type I atrial flutter. They underline the importance of the right heart preload and atrial size for the electrophysiological characteristics of type I atrial flutter. Beside its fundamental interest, this finding is important for the understanding of the mechanism of maintenance and therapeutic responses of this common arrhythmia.     

Friction, capacitance and transepidermal water loss (TEWL) in dry atopic and normal skin

The biophysical properties of non-eczematous skin at three locations in atopics and non-atopics were characterized using non-invasive physical methods. Skin friction was measured with a newly developed sliding friction instrument, the degree of hydration with a capacitance meter (Corneometer CM 820), and the transepidermal water loss (TEWL) was determined using an Evaporimeter EP1. The areas examined (dorsum of the hand, volar forearm and lower back) showed lower values of friction and capacitance in the atopic patients than did corresponding sites in the normal controls. In most areas a significant correlation between friction and capacitance was found. The TEWL was increased in atopic skin, but TEWL seems to correlate neither to friction nor to capacitance.     

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.     

Structure-activity studies of hydrophobic amino acid replacements at positions 9, 11 and 16 of glucagon

We have designed and synthesized eight compounds 2-9 which incorporate neutral, hydrophobic amino acid residues in positions 9, 11 and 16 of the glucagon molecule: (2) [desHis¹,Va1⁹,11e^11,16] glucagon amide, (3) [desHis¹,Val^9,11,16]glucagon amide, (4) [desHis¹,Va1⁹,Leu^11,16]glucagon amide, (5) [desHis¹,Nle⁹,11e^11,16]glucagon amide, (6) [desHis¹,Nle⁹,Val^11,16]glucagon amide, (7) [desHis¹,Nle⁹,Leu^11,16]glucagon amide, (8) [desHis¹,Val⁹,Leu^11,16,Lys^17,18,Glu²¹]glucagon amide and (9) [desHis¹,Nle⁹,Leu^11,16,Lys^17,18,Glu²¹]glucagon amide. The effect of neutral, hydrophobic residues at positions 9, 11 and 16 led to good binding to the glucagon receptor. Compared to glucagon (IC₅₀= 1.5 nM), analogues 2-9 were found to have IC₅₀ values of 6.0, 6.0, 11.0, 9.0, 2.5, 2.8, 6.5 and 7.0 nM, respectively. When these compounds were tested for their ability to block adenylate cyclase (AC) activity, they were found to be antagonists having no stimulation of adenyl cyclase, with PA₂, values of 6.15, 6.20, 6.30, 7.25, 6.10, 7.30, 6.25 and 7.25, respectively. © Munksgaard 1997.     

Pulmonary Bioavailability and Fine Particle Enrichment of 2,3,7,8-Tetrachlorodibenzo-p-dioxin in Respirable Soil Particles

The pulmonary bioavailability of 2,3,7,8-tetrachlorodibenzo-p-dioxin(TCDD) and the enrichment of polychlorinated dioxins (PCDDs)and furans (PCDFs) in fine particles were evaluated to assessthe implications that these factors have on risk and exposureassessments. Respirable subfractions of PCDD-contaminated soilfrom a former 2,4,5-trichlorophenoxyacetic acid manufacturingsite were isolated by chemical dispersion and gravity sedimentation.Analysis of the subfractions revealed that there was a size-dependentenrichment of PCDDs and PCDFs, with smaller particles more highlycontaminated. TCDD was enriched up to 33-fold as compared tounfractionated soil. Soil and laboratory-recontaminated galliumoxide, which served as the positive control, were administeredby intratracheal instillation to female Sprague-Dawley rats.Animals were terminated up to 28 days following treatment andpulmonary bioavailability of TCDD was assessed by hepatic enzymeinduction and TCDD concentration. Enzyme induction was dependenton the duration of exposure with up to 56 and 918% increasesin cytochrome P450 and aryl hydrocarbon hydroxylase (AHH) activity,respectively, following exposure to PCDD-contaminated soil.There was no significant difference in AHH induction betweenanimals which received contaminated soil and those treated withthe positive control. Hepatic concentration of TCDD in soil-exposedrats was 115, 101, and 179% of positive controls at 1, 7, and28 days post-treatment, suggesting that the soil or co-contaminantsinfluenced retention of TCDD in the liver. These data indicatethat the relative pulmonary bioavailability of TCDD on respirablesoil particles is 100% as compared to laboratory-recontaminatedgallium oxide and that PCDDs and PCDFs are highly enriched onrespirable particles. Utilization of these results will reducethe uncertainty and improve the accuracy of envi ronmental riskassessments of PCDDs and PCDFs.