Farmer's lung is now in decline

Farmer's lung incidence in Ireland was constant until 1996, even though hay making methods were revolutionised in late 1980's. We undertook this study to find out the incidence of farmer's lung in Ireland from 1982-2002 and its correlation with rainfall and the effect of changing farm practices. The primary cases of farmer's lung were identified from Hospital in Patients Enquiry (HIPE) unit of the national Economic & Social Research Institute (ESRI) Dublin. Rainfall data were obtained from Met Eireann whereas population, hay production and silage production were obtained from the Central Statistics Office, Dublin. As the farming population is in decline, we used the annual working unit (AWU), which reflects the true population at risk. An AWU is the equivalent of 1800 hours per farm worker per year. The incidence rates were constant from 1982-1996, but from 1997-2002 a marked decline was observed. There was strong positive correlation with hay production (r = 0.81) and strong negative correlation with silage production (r = -0.82). This study indicates that the incidence of farmer's lung is now in decline.

Heart Rate Variability: Does it Change After RF Ablation of Reentrant Supraventricular Tachycardia?

BACKGROUND

Following RF ablation of reentrant supraventricular tachycardia, inappropriate sinus tachycardia may occur. Local parasympathetic denervation is a possible mechanism for these rhythm disturbances. The purpose of this study was to determine the incidence of sinus tachycardia and to determine the relation between endocardial lesions at different ablation sites and alterations in autonomic tone in several different groups of patients with supraventricular tachycardia, using techniques of heart rate variability analysis.

METHODS

The subjects of this study were 75 patients (48 women, 27 men) with a mean age of 39.99 (SD = 13.39). They underwent RF ablation of AV nodal slow pathways (40 cases), posteroseptal APs (23 cases), left lateral and right free wall APs (12 cases) because of symptomatic tachycardias. The mean sinus rate and time domain (standard deviation of RR intervals and root mean square of differences of adjacent RR intervals) and frequency domain (low frequency, high frequency and low frequency/high frequency ratio) analyses of heart rate variability were obtained by use of 24 hour Holter monitoring before and 1 month after ablation compared with pre-ablation values.

RESULTS

Analysis of 24 hour ambulatory Holter-monitors, performed 1 month after RF ablation, showed no significant changes in time and frequency domain parameters of heart rate variability in different groups. A significant increase in mean heart rate was noted after RF ablation at AV nodal slow pathway group and left freewall/right free wall accessory pathways group. Patients undergoing RF ablation of right or left posteroseptal accessory pathways had no significant increase in the mean heart rate.

CONCLUSION

In summary, an increase in sinus tachycardia may be initiated by RF ablation of atrioventricular reentrant tachycardia (AVNRT) and right free wall or left free wall accessory pathways. This finding shows that the modifications of heart rate are not directly related to the posteroseptal region or to the accessory pathways.

Resolution of tachycardia-induced cardiomyopathy following ablation of verapamil-sensitive idiopathic left ventricular tachycardia

Few reports have described tachycardia-induced cardiomyopathy secondary to ventricular tachycardia. We present a 12-year-old boy with dilated cardiomyopathy and incessant verapamil-sensitive idiopathic left ventricular tachycardia. Twelve-lead electrocardiogram showed right bundle branch block QRS morphology with superior axis during tachycardia. Electrophysiology study confirmed the diagnosis, and radiofrequency ablation was done and successfully terminated and prevented induction of ventricular tachycardia. During the follow-up period of 18 months, the patient remained free of symptoms and arrhythmia. Three months after ablation, left ventricular ejection fraction improved and cardiac silhouette became normal on chest x-ray.

Radiofrequency ablation of accessory pathways

INTRODUCTION

17 years ago the first radiofrequency catheter ablation of an accessory pathway (AP) was performed. The aim of this study was to describe the contemporary success rates and procedure related complication rates of radiofrequency (RF) ablation of accessory pathways (APs). In addition, the present study describes the anatomical distribution of APs according to the new nomenclature introduced by NASPE and ESC in 1999.

METHODS

The analysis included all patients, who underwent RF ablation of an AP in the Heart Center Leipzig between January 2000 and December 2003.

RESULTS

Over a 4 year period 336 APs were ablated in 323 patients. 201 APs (60%) presented with antegrade and retrograde conduction and showed preexcitation on ECG. For the remaining 135 APs (40%), only retrograde conduction over the AP was documented. According to the new nomenclature APs were classified as left-sided, right sided, septal and paraseptal APs. 188 APs (56%) were located on the left, 41 (12%) on the right, 64 (19%) in the paraseptal space and 31 APs (9%) presented with a septal or parahisian localization, respectively. Because of atypical course and/or characteristics 12 APs (4%) could not be classified. Ablation of all pathways were successful in 315 patients (98%). In 289 patients (89%) success was achieved within a single ablation session. The left-sided pathways had a re-intervention rate of 5%, which was significantly lower compared to the remaining localizations. The highest re-intervention rate was observed in the septal APs (23%). Complications were observed in less than 2% of all treated patients.

CONCLUSIONS

17 years after the first RF catheter ablation of an AP this therapy is established as a highly effective procedure. The success rate has improved to 98% and the complication rate has been minimized to less than 2%. The most frequent localization of APs is left posterior. Left sided APs also presented with the lowest re-intervention rate. The introduction of the new nomenclature in 1999 by NASPE and ESC has simplified the description of the exact anatomical localization of an AP.

Double-blind randomized controlled study of coblation tonsillotomy versus coblation tonsillectomy on postoperative pain

This double-blind randomized controlled trial of coblation tonsillotomy versus coblation tonsillectomy uses visual analogue scoring to compare the pain experienced in the 24h postoperative period. No statistically significant difference in pain is demonstrated in the group of 14 patients studied. Tonsillectomy is recommended over tonsillotomy.

Intestinal mast cell progenitors require CD49dbeta7 (alpha4beta7 integrin) for tissue-specific homing

Mast cells (MCs) are centrally important in allergic inflammation of the airways, as well as in the intestinal immune response to helminth infection. A single lineage of bone marrow (BM)-derived progenitors emigrates from the circulation and matures into phenotypically distinct MCs in different tissues. Because the mechanisms of MC progenitor (MCp) homing to peripheral tissues have not been evaluated, we used limiting dilution analysis to measure the concentration of MCp in various tissues of mice deficient for candidate homing molecules. MCp were almost completely absent in the small intestine but were present in the lung, spleen, BM, and large intestine of beta7 integrin-deficient mice (on the C57BL/6 background), indicating that a beta7 integrin is critical for homing of these cells to the small intestine. MCp concentrations were not altered in the tissues of mice deficient in the alphaE integrin (CD103), the beta2 integrin (CD18), or the recombination activating gene (RAG)-2 gene either alone or in combination with the interleukin (IL)-receptor common gamma chain. Therefore, it is the alpha4beta7 integrin and not the alphaEbeta7 integrin that is critical, and lymphocytes and natural killer cells play no role in directing MCp migration under basal conditions. When MCp in BALB/c mice were eliminated with sublethal doses of gamma-radiation and then reconstituted with syngeneic BM, the administration of anti-alpha4beta7 integrin, anti-alpha4 integrin, anti-beta7 integrin, or anti-MAdCAM-1 monoclonal antibodies (mAbs) blocked the recovery of MCp in the small intestine. The blocking mAbs could be administered as late as 4 d after BM reconstitution with optimal inhibition, implying that the MCp must arise first in the BM, circulate in the vasculature, and then translocate into the intestine. Inasmuch as MCp are preserved in the lungs of beta7 integrin-deficient and anti-alpha4beta7 integrin-treated mice but not in the small intestine, alpha4beta7 integrin is critical for tissue specific extravasation for localization of MCp in the small intestine, but not the lungs.

Predictors of visual acuity and the relative afferent pupillary defect in optic neuropathy

The relationships among visual acuity (log MAR), diagnostic category, age, the magnitude of a relative afferent pupillary defect (RAPD) in log units, photopic foveal thresholds to white and colored light (dB), and the mean deviation on the Humphrey visual field (dB) were studied in patients with various optic neuropathies. All acuity and dB values were expressed as interocular differences, the majority of cases having normal acuity in the fellow eye. In multiple regression analyses, acuity and RAPD were alternately chosen as the dependent or response variable with all remaining variables serving as the predictors or independent variables. The main finding was that the only significant predictor of a RAPD was the interocular mean deviation difference on the Humphrey field and the only significant predictor of acuity was the foveal threshold to white light. Redundant and insignificant variables were therefore identified with multiple regression analysis. Subsidiary findings include: (a) although diagnostic group was not a significant predictor in the above, simple linear regression line slopes relating RAPD magnitude to the Humphrey mean deviation were significantly different between optic neuritis and compression categories; (b) for a given level of acuity, foveal thresholds were substantially worse in these cases with neuronal damage than in strabismic amblyopia, refractive error, or corneal damage; and (c) sensitivity losses for red vs. blue light were similar.

Mucosal T lymphocyte numbers are selectively reduced in integrin alpha E (CD103)-deficient mice

The mucosal lymphocyte integrin alpha E(CD103)beta 7 is thought to be important for intraepithelial lymphocyte (IEL) localization or function. We cloned the murine integrin gene encoding alpha E, localized it to chromosome 11, and generated integrin alpha E-deficient mice. In alpha E-/- mice, intestinal and vaginal IEL numbers were reduced, consistent with the known binding of alpha E beta 7 to E-cadherin expressed on epithelial cells. However, it was surprising that lamina propria T lymphocyte numbers were diminished, as E-cadherin is not expressed in the lamina propria. In contrast, peribronchial, intrapulmonary, Peyer's patch, and splenic T lymphocyte numbers were not reduced in alpha E-deficient mice. Thus, alpha E beta 7 was important for generating or maintaining the gut and vaginal T lymphocytes located diffusely within the epithelium or lamina propria but not for generating the gut-associated organized lymphoid tissues. Finally, the impact of alpha E deficiency upon intestinal IEL numbers was greater at 3-4 wk of life than in younger animals, and affected the TCR alpha beta+ CD8+ T cells more than the gamma delta T cells or the TCR alpha beta+ CD4+CD8- population. These findings suggest that alpha E beta 7 is involved in the expansion/recruitment of TCR alpha beta+ CD8+ IEL following microbial colonization. Integrin alpha E-deficient mice will provide an important tool for studying the role of alpha E beta 7 and of alpha E beta 7-expressing mucosal T lymphocytes in vivo.