42 W femtosecond Yb:Lu2O3 regenerative amplifier

We report on a femtosecond high-power regenerative amplifier based on Yb:Lu₂O₃. Exploiting the excellent thermo-mechanical properties of this material, we were able to achieve up to 64.5 W in continuous-wave regime, limited only by the available pump power. In pulsed operation, 42 W of average output power at a repetition rate of 500 kHz with 780 fs long pulses could be demonstrated, resulting in a pulse peak power of ∼100  MW. The spectrum was centered at 1034 nm with an FWHM of 2.4 nm, potentially allowing for even shorter pulses. At the maximum output power the beam was nearly TEM₀₀, with an M² value of 1.2 in both axes.

Single-grating-mirror intracavity stretcher design for chirped pulse regenerative amplification

We report for the first time, to the best of our knowledge, an innovative design concept for intracavity pulse stretching in a regenerative amplifier, employing a single "grating-mirror" based on a leaky-mode grating-waveguide design. The very compact and flexible layout allows for femtosecond pulses to be in principle easily stretched up to nanosecond durations. The design has been tested in a diode-pumped Yb:CALGO regenerative amplifier followed by a standard transmission grating compressor. Sub-200-fs pulses (stretched pulses ≈110  ps) with 205-μJ energy at 20-kHz repetition rate have been demonstrated. In order to prove the robustness and potential for energy scaling of leaky-mode grating-waveguide intracavity stretcher, we generated stretched pulses with energies of up to ≈700  μJ (400-ps long) at a lower repetition rate of 10 kHz. A simple model is proposed for the study of the cavity in presence of induced spatial chirp.

High pulse energy multiwatt Yb:CaAlGdO4 and Yb:CaF2 regenerative amplifiers

We investigated and compared Yb:CaAlGdO4 and Yb:CaF2 regenerative amplifiers at repetition rates 5-10 kHz, a frequency range interesting for industrial applications requiring relatively high pulse energy. Both materials allow for pulse energies close to 1 mJ with sub-400-fs pulses. The two laser materials offer comparable performance in the pump power range investigated. The same regenerative amplifiers can be run up to 500 kHz for much faster material processing, with maximum output power of up to 9.4 W.

28-W, 217 fs solid-state Yb:CAlGdO4 regenerative amplifiers

A new high-performance Yb:CaAlGdO(4) (Yb:CALGO) regenerative amplifier is demonstrated. Pumped by 116 W at ≈980 nm and seeded by means of a 92 fs oscillator, it generates as much as 36 W of average output power with chirped pulses, and 28 W with 217 fs compressed pulses at 500 kHz repetition rate. This corresponds to 56 μJ of pulse energy and 258 MW peak power. The compressed pulses have a time-bandwidth product of 0.69 and could be shortened further with an improved compressor setup.

Rapid progression of pericardial calcification in a patient with end-stage renal disease

Dialysis pericarditis is a relatively uncommon cause of pericardial constriction and may be found in patients with end-stage renal disease receiving adequate renal replacement therapy. We present a patient with end-stage renal disease maintained on chronic peritoneal dialysis who developed severe myopericardial calcification over a 2-month period demonstrated by sequential chest computed tomographic scanning. The characteristic hemodynamic findings of constrictive-effusive pericarditis, obtained during cardiac catheterization, are presented and discussed.

The use of topical diphenylcyclopropenone for the treatment of extensive alopecia areata

BACKGROUND

Highly variable results of topical diphenylcyclopropenone (DPCP) in the treatment of alopecia areata have been reported so far.

OBJECTIVE

The purposes of our study were to evaluate the efficacy and tolerability of DPCP in the treatment of chronic, extensive alopecia areata and to assess the long-term overall benefit of treatment.

METHODS

Fifty-six patients with chronic, extensive alopecia areata were enrolled in an open-label clinical trial. After sensitization with 2% DPCP, progressively higher concentrations beginning at 0.001% were applied weekly for 6 to 12 months to one side of the scalp.

RESULTS

Fifty-two of 56 patients completed therapy. Total regrowth of terminal hair was achieved in 25 of 52 patients (48%) at 6 months. The most frequent side effect was an eczematous reaction at the site of application. Notably, persistent response was observed in 60% of these patients after 6 to 18 months of follow-up (mean, 12 months).

CONCLUSION

Topical DPCP treatment for alopecia areata is effective and well tolerated and provides prolonged therapeutic benefits.

Cutaneous epithelioid cell histiocytoma: immunohistochemical and ultrastructural findings suggesting endothelial origin

A 13-year-old boy presented with a polypoid nodule localized in the groin. Although the clinical and histopathological features corresponded to previously described diagnostic criteria of epithelioid cell histiocytoma, immunohistochemical and ultrastructural findings suggested vascular differentiation of the epithelioid cells. In particular, the immunohistochemical negativity of the epithelioid cell elements for Factor XIIIa failed to substantiate the previously forwarded hypothesis that this lesion represents a dendrocytoma. Instead, the presence of histiocytoid, vacuolated cells occasionally containing sparse red blood cells, positive staining for Factor VIII-related antigen, and ultrastructural evidence of endothelial characteristics in epithelioid neoplastic cells favor the hypothesis that "epithelioid cell histiocytoma" is of endothelial origin. We suggest the descriptive term cutaneous histiocytoid hemangioendothelioma for this lesion.

Primary centroblastic/centrocytic lymphoma of the skin. Detection of B-cell monoclonality by polymerase chain reaction

A 60-year-old woman was examined for erythematous plaques and nodules on the back that had appeared 1 year earlier. Histologic examination of a skin biopsy specimen showed a dense, diffuse infiltrate throughout the dermis and subcutis, composed mainly of centroblasts and centrocytes. Immunohistochemistry confirmed positivity of the neoplastic cells for L26 (CD20) and LN1 (CDw75) antibodies and negativity for UCHL1 (CD45RO), polyclonal anti-CD3, anti-kappa, and anti-lambda antibodies. Polymerase chain reaction (PCR) analysis on paraffin-embedded tissue sections of the cutaneous lesion showed immunoglobulin heavy-chain (VDJ) and kappa-chain gene rearrangement. Routine laboratory studies were within normal limits. The staging workup of the patient (bone marrow biopsy, computed tomographic scans of the chest and abdomen) showed no abnormalities. Based on clinicopathologic findings and molecular analysis, a diagnosis of primary cutaneous centroblastic/centrocytic lymphoma was made. The patient was treated with intra- and perilesionally administered recombinant interferon alpha-2a (3 x 10(6) IU) three times a week for 2 months. Complete response was achieved, and no evidence of recurrence has been observed after 18 months of follow-up.

The safety of intracoronary ultrasound. A multicenter survey of 2207 examinations

BACKGROUND

Intracoronary ultrasound (ICUS) is increasingly used in clinical practice to study the natural history of coronary artery disease and to assess the effects of intracoronary, catheter-based interventions. However, the risk associated with the procedure is not well documented.

METHODS AND RESULTS

ICUS studies performed in 28 centers were retrospectively included; these centers agreed to contribute to the study among a total of 60 centers initially invited. Among the 2207 ICUS studies, 505 (23%) were performed in heart transplant recipients and 1702 (77%) in nontransplant patients. Indication for ICUS was diagnostic imaging in 915 (41%), drug testing in 244 (11%), and guidance for intracoronary interventions in 1048 patients (47%). There were no complications in 2034 patients (92.2%). In 87 patients (3.9%), complications occurred but were judged to be "not related" to ICUS by the operator. In 63 patients (2.9%), spasm occurred during ICUS imaging. In 9 patients (0.4%), complications other than spasm were judged to have a "certain relation" to ICUS, including acute procedural events in 6 (3 acute occlusion, 1 embolism, 1 dissection, and 1 thrombus) and major events in 3 patients (2 occlusion and 1 dissection; all resulting in myocardial infarction). In 14 patients (0.6%), complications with "uncertain relation" to ICUS were recorded, including acute procedural events in 9 (5 acute occlusion, 3 dissection, and 1 arrhythmia) and major events in 5 patients (2 myocardial infarction and 3 emergency coronary artery bypass surgery). The incidence of acute procedural or major complications judged to be associated with ICUS (uncertain relation or certain relation to ICUS) was compared in different patient groups. The complication rate was higher in patients with unstable angina or acute myocardial infarction (2.1% events) as compared with patients with stable angina pectoris and asymptomatic patients (0.8% and 0.4%, respectively; chi 2 = 10.9, P < .01). These complications were also more frequent in patients undergoing interventions (1.9%) as compared with transplant and nontransplant patients undergoing diagnostic ICUS imaging (0% and 0.6%, respectively; chi 2 = 13.5, P < .001). Adverse events were few, and no association was detected between these events and the size or type of ICUS catheter used.

CONCLUSIONS

ICUS is associated with (but not necessarily the direct cause of) a minor acute clinical risk. Vessel spasm is the most frequent event occurring during ICUS. Other complications predominantly occur in patients with acute coronary syndromes and during guidance for intervention.

Intraaortic balloon pump support during high-risk coronary angioplasty

Intraaortic balloon pump support has been demonstrated to be of clinical benefit when used therapeutically and prophylactically in high-risk patients undergoing percutaneous transluminal coronary angioplasty (PTCA). Afterload reduction and post-PTCA-enhanced coronary blood flow afforded by diastolic augmentation during intraaortic balloon pumping provides hemodynamic stabilization, attenuates clinical perturbations of myocardial ischemia, and may provide an important 'bridge' to emergent coronary bypass surgery following abrupt vessel closure complicating PTCA. Recent studies demonstrate a reduction in cardiac morbidity and improved coronary artery patency among patients receiving prophylactic intraaortic balloon pumping after establishing infarct artery reperfusion during acute cardiac catheterization for acute myocardial infarction. A modest increase in cardiac output (20-30%), the requirement of a stable, regular cardiac rhythm, peripheral vascular disease and aortic insufficiency limits the use of intraaortic balloon pump support in relatively few patients. These studies demonstrate that intraaortic balloon counterpulsation provides an effective and safe form of mechanical support in many high-risk patients undergoing PTCA.

Autonomic manipulation influences both temporal and frequency analyses of late potentials

Previous studies of late potentials have not standardized the autonomic milieu at the time of testing. We studied the effects of autonomic manipulation in seven patients with previous Q wave myocardial infarction. Late potentials were evaluated using standard temporal (TD) and spectral temporal mapping techniques (STM) in the drug free state, and during separate intravenous administration of each of the following: isoproterenol, esmolol, and atropine. Isoproterenol was titrated to achieve a heart rate of 130% of baseline. Esmolol was infused at a rate of 250 micrograms/kg per minute, after a loading dose of 500 micrograms/kg. Atropine was given as a 2-mg bolus. In addition, five patients who received no drug infusions acted as controls, undergoing four serial signal-averaging studies in the baseline state: a "baseline" study, and then three additional studies at time intervals similar to those incurred by the study patients. Therefore, a total of 21 TD and 21 STM tests were done in the study group (seven patients; three drugs per patient) during the drug infusions, and 15 TD and 15 STM tests were done in the control group (five patients; three "nonbaseline" tests per patient). A change (normal to abnormal, or vice versa) in TD during a drug infusion occurred in 24% of the tests. No such change occurred in the control group (P < 0.01). A change in STM during a drug infusion occurred in 38% of tests, versus 13% of tests in the control group (P = 0.14). Overall, six of seven patients had a change in TD and/or STM diagnosis with infusion of one or more of the study drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

General arousal and performance

The effect of different levels of arousal on performance (of perception and of learning) was studied in 28 subjects, both men and women whose ages ranged from 17 to 25 yr. The tasks were two tactile discrimination tests, one which required learning and memorizing and the other one visual discrimination. The latter test has been used as an interference task in learning and memorizing. Results suggest the fundamental role of general arousal in determining good performance. Tactile perception and visual discrimination under high arousal have been better than those in a relaxed condition, the disturbing task interfered more with performance under a relaxed condition than with that under high arousal.