Phenotypic Characterization of Recent Clonal Lineages of Phytophthora infestans in the United States.

Phytophthora infestans, the causal agent of late blight disease, has been reported in the United States and Canada since the mid-nineteenth century. Due to the lack of or very limited sexual reproduction, the populations of P. infestans in the United States are primarily reproducing asexually and, thus, show a simple genetic structure. The emergence of new clonal lineages of P. infestans (US-22, US-23, and US-24) responsible for the late blight epidemics in the northeastern region of the United States in the summers of 2009 and 2010 stimulated an investigation into phenotypic traits associated with these genotypes. Mating type, differences in sensitivity to mefenoxam, differences in pathogenicity on potato and tomato, and differences in rate of germination were studied for clonal lineages US-8, US-22, US-23, and US-24. Both A1 and A2 mating types were detected. Lineages US-22, US-23, and US-24 were generally sensitive to mefenoxam while US-8 was resistant. US-8 and US-24 were primarily pathogenic on potato while US-22 and US-23 were pathogenic on both potato and tomato. Indirect germination was favored at lower temperatures (5 and 10°C) whereas direct germination, though uncommon, was favored at higher temperatures (20 and 25°C). Sporangia of US-24 released zoospores more rapidly than did sporangia of US-22 and US-23. The association of characteristic phenotypic traits with genotype enables the prediction of phenotypic traits from rapid genotypic analyses for improved disease management.

Profiles of automated peritoneal dialysis prescriptions in the US 1997-2003.

Automated peritoneal dialysis (PD) is the dominant mode of delivery of PD in the US. Information about actual prescribing patterns has been limited. The present study examines cycler prescription use in large cohorts during the years 1997, 2000, and 2003. We observed trends consisting of increasing fill volumes, increasing time on cycler, lowering of the number of cycles, and a shift in the reason for utilization of tidal therapy. Monitoring of practice patterns is beneficial in identifying opportunities for practice enhancement. The findings of the present survey demonstrate trends that approach standard recommendations of the benefits of increasing fill volume whereas paying close attention to dwell time as a balance between cycle number and therapy duration. Furthermore, this survey shows that the cycler represents a flexible method to personalize PD therapy.

Left bundle branch block and right axis deviation: a report of 36 cases.

Right axis deviation (RAD) with left bundle branch block (LBBB) is a rare combination. From a database of 636,000 electrocardiograms we report a series of 36 patients with this disorder. The majority of subjects had dilated cardiomyopathy with biventricular enlargement. LBBB was fixed in 21 of 36 cases. It was freshly acquired, episodic, intermittent, or physiologic in 15 of 36. The RAD was episodic in 30 of 36; it was fixed and concurrent with LBBB in only 2 cases, and never episodically concurrent. Reported for the first time here were 4 of 36 cases in which the combination of LBBB and RAD was elicited with atrial premature impulses as a rare form of QRS aberration. In one case where the combination was intermittent, a clear relationship with freshly acquired intermittent posterior fascicular block was demonstrated. The possible relationship of the deviation with variable degrees of right ventricular overload is discussed.

QT interval analysis on ambulatory electrocardiogram recordings: a selective beat averaging approach.

A computerised method for the analysis of QT intervals in ambulatory ECG recordings is presented. This approach is based on selective beat averaging which allows one to process P-QRS-T complexes together with the environment that characterises them. Long-term autonomic nervous system influences are accounted for by separating the analysis over different circadian periods. Effects of QT recovery time are taken into account by requiring a stable heart rate preceding each beat to be averaged. Before averaging, beats are resampled and realigned with respect to the R-wave peak estimated by parabolic interpolation. Averaged ECG templates are then analysed with an algorithm which automatically detects QRS complex and T-wave features. Repolarisation analysis is based on first and second derivatives of lowpass filtered ECG (recursive Butterworth filter). The QT/RR relationship and the circadian QT variation at identical heart rate were analysed in 14 normal individuals. When performed at stable heart rate conditions and when confined to well-defined circadian periods, the QT/RR relationship was strongly linear (r = 0.95 +/- 0.06); in addition, the slope of this relation changed between day and night (respectively, 0.197 +/- 0.07 and 0.139 +/- 0.03, p < 0.01). The range of circadian QT variation at identical heart rate was approximately 20 ms for both males and females.

Prospective evaluation of a microprocessor-assisted cardiac rhythm algorithm: results from one clinical center.

A new microprocessor-assisted cardiac rhythm algorithm (MAC-RHYTHM), based on median QRST subtraction from 10-second electrocardiographic (ECG) data, was prospectively tested on 10,761 ECGs acquired at one of three clinical centers. Atrial waves (P waves, atrial fibrillatory waves, and flutter waves) were detected from the median QRST-subtracted residual signals. Rhythm criteria were applied to the detected atrial waves and their temporal relation to QRS complexes for generating rhythm interpretations. Rhythm statements generated by MAC-RHYTHM were compared against the true rhythm of the ECGs as read by an experienced cardiologist. The results of prospective testing were compared with the results of an earlier retrospective testing using MAC-RHYTHM and a released commercial ECG analysis program on stored ECGs. The prospective results were very similar to the results of MAC-RHYTHM on retrospective data for all the rhythms examined (sinus rhythms, atrial fibrillation, atrial flutter, junctional rhythms, second degree atrioventricular blocks). For three of the abnormal rhythms, namely, atrial fibrillation, junctional rhythms, and second degree atrioventricular blocks, MAC-RHYTHM gave significantly higher sensitivity in both prospective (87.5%, 92.2%, and 80.8%, respectively) and retrospective (82.0%, 81.2%, and 79.6% respectively) testing than the released commercial ECG analysis program (65.0%, 39.6%, and 12.0% respectively). Similarly, for sinus rhythms, MAC-RHYTHM had significantly higher specificity (prospective, 91.0% and retrospective, 91.7%) than the released commercial program (86.5%). The specificity for the abnormal rhythms remained very high with MAC-RHYTHM (prospective, 99.4% to 99.7% and retrospective, 99.1% to 99.7%) compared to the released commercial program (99.0% to 99.9%). This prospective study also indicated that further work is needed to improve the detection of pacemaker spikes and the interpretation of paced rhythms in 10-second resting ECGs.

Prophylaxis and treatment of NSAID-induced gastropathy.

Because the gastrointestinal complications of nonsteroidal anti-inflammatory drug (NSAID) use may be responsible for over 10,000 deaths each year, clinicians should consider limiting use of these agents. Risk factors such as previous ulcer disease, high dosage, concomitant corticosteroid use, age greater than 60 years and use of more than one NSAID concomitantly should be reviewed. If a patient has two or more risk factors, prophylaxis with misoprostol is indicated. In low-risk patients, prophylaxis with misoprostol is not indicated because of the risk of gastrointestinal side effects and high cost. Although it is common clinical practice to treat NSAID-induced dyspepsia with prophylactic antiulcer therapy, clinical studies do not support this approach. If an ulcer develops during NSAID therapy, treatment with a histamine H2 antagonist should be started. Discontinuation of the NSAID is recommended but is not necessary for ulcer healing. It is recommended that, once the ulcer heals, the patient also take misoprostol if NSAID usage is continued.

Electrocardiographic changes during acute treatment of hypertensive emergencies with sodium nitroprusside or fenoldopam.

BACKGROUND: Electrocardiograms are routinely obtained before and during the acute treatment of hypertensive emergencies, usually to rule out "ischemic changes." Despite a few anecdotal reports of electrocardiographic changes, little is known about the incidence and significance of such changes, or their relationship to the treatment used. METHODS: We prospectively analyzed 12-lead electrocardiograms from 21 patients admitted for hypertensive emergencies (average blood pressure, 222 +/- 4/140 +/- 3 mm Hg). Patients were randomly assigned to treatment with sodium nitroprusside (n = 11) or the dopamine receptor agonist fenoldopam mesylate (n = 10). Electrocardiograms were obtained at baseline and within 30 minutes of reaching goal blood pressure (diastolic blood pressure, 100 to 110 mm Hg). RESULTS: There was no significant effect of either drug treatment on PR interval, QRS duration, QT interval, or R-wave amplitude, and no major ST-segment changes were noted. During treatment with either drug, the average T-wave amplitude decreased in all leads except aVR. New T-wave inversions in lead V4 occurred in two and four patients after fenoldopam and nitroprusside treatment, respectively. There were no clinically apparent episodes of myocardial ischemia in any patient. CONCLUSIONS: Even in the absence of obvious myocardial ischemia, a decrease in T-wave amplitude, including T-wave inversion, occurs commonly during acute blood pressure reduction in hypertensive emergencies, an observation that may be explained by the accompanying acute changes in cardiac chamber volumes.

Torsade de pointes complicating acute myocardial infarction: the importance of autonomic dysfunction as assessed by heart rate variability.

Torsade de pointes is a polymorphic ventricular tachycardia associated with QT-interval prolongation rarely reported to occur in the setting of an acute myocardial infarction. Autonomic dysfunction has been implicated as a major stimulus for the development of this dysrhythmia. We describe the case of an 80-year-old woman who presented with an acute myocardial infarction and progressive QT-interval lengthening. An 89-beat run of torsade de pointes occurred during the time of the peak creatine phosphokinase (CPK) without electrolyte abnormalities or antiarrhythmic therapy. Assessment of autonomic tone using power spectral analysis of two consecutive 24-h Holter recordings was performed indicating that a transient decrease in heart rate variability and increase in sympathetic tone preceded the tachyarrhythmia. This case shows the potential usefulness of heart rate variability analysis as a marker for autonomic dysfunction and arrhythmogenesis, particularly during myocardial ischemia.

ST segment alternans during coronary angioplasty.

Four patients with severe proximal or mid-LAD stenosis were noted to have ST alternans during balloon angioplasty. Neither mechanical alternans nor increased ventricular ectopy were noted. In contrast to prior descriptions in animals or patients with variant angina, ST alternans did not occur following a premature ventricular contraction. Frequent use of calcium channel blockers during PTCA may interfere with the mechanism leading to electrical alternans and its consequences as seen in animal studies, accounting for the low frequency with which this phenomenon is noted during PTCA.

Lesser metatarsal stress fractures: a study of 37 cases.

A study of lower-extremity stress fractures is presented with emphasis placed on metatarsal stress fractures. The metatarsals were found to be the second most common site in the study. The study documents not only the number of metatarsal stress fractures found, but also the location within the affected metatarsal. Because stress fractures are a common problem, especially for the military recruit or athlete, metatarsal stress fractures can represent a common cause of metatarsalgia.