Spatio-temporal analysis of glass volume processing using ultrashort laser pulses.

Ultrashort laser pulses allow for the in-volume processing of glass through non-linear absorption, resulting in permanent material changes and the generation of internal stress. Across the manifold potential applications of this technology, process optimization requires a detailed understanding of the laser-matter interaction. Of particular relevance are the deposition of energy inside the material and the subsequent relaxation processes. In this paper, we investigate the spatio-temporal evolution of free carriers, energy transfer, and the resulting permanent modifications in the volume of glass during and after exposure to femtosecond and picosecond pulses. For this purpose, we employ time-resolved microscopy in order to obtain shadowgraphic and interferometric images that allow relating the transient distributions to the refractive index change profile. Whereas the plasma generation time is given by the pulse duration, the thermal dynamics occur over several microseconds. Among the most notable features is the emergence of a pressure wave due to the sudden increase of temperature and pressure within the interaction volume. We show how the structure of the modifications, including material disruptions as well as local defects, can be directly influenced by a judicious choice of pulse duration, pulse energy, and focus geometry.

Autologous stem cell transplantation for follicular lymphoma: no benefit for early transplant?

Autologous stem cell transplantation (SCT) is widely used as salvage treatment for patients with relapsed follicular lymphoma (FL). Although SCT can induce prolonged remissions, it does not appear to be curative in the vast majority of patients. The purpose of this study was to investigate if incorporation of SCT into first-line therapy can improve its efficacy. Fifty-five patients underwent sequential high-dose therapy as up-front (n=33) or salvage treatment (n=22) for advanced stage FL at our institution. Treatment consisted of intensive chemotherapy with dexamethasone, carmustine (BCNU), etoposide, cytarabine, and melphalan (Dexa-BEAM) for mobilization of peripheral stem cells and reduction of tumor load, followed by one of three different myeloablative regimens and SCT. With a median follow-up of 4 years, projected event-free survival (EFS) and overall survival (OS) at 4 years post transplant was 59% and 84%, respectively, with no evidence of plateau in the survival curves. By univariate and multivariate analysis weighing age, sex, stage, BM and extranodal involvement, timing of transplant, ex vivo purging, and conditioning regimen [total body irradiation (TBI) vs non-TBI], the only significant factor predicting for superior EFS and OS was up-front vs salvage transplant (4-year EFS 76% vs 38%, p=0.02; 4-year OS 92% vs 73%, p=0.033). However, when calculated from diagnosis, EFS and OS of the up-front and salvage groups were virtually identical, implying that the longer survival post SCT in the up-front group was completely compensated by the longer interval between diagnosis and transplant in the salvage group. Median OS from diagnosis was 13.5 years. Except for one case of anaplastic large cell lymphoma, secondary neoplasms have not occurred to date. In conclusion, our data indicate that SCT might improve the prognosis of patients with disseminated FL, although it is probably not curative even if applied early during the course of the disease. The optimum timing of SCT remains to be determined by the ongoing randomized multicenter trial of the German Low-grade Lymphoma Study Group. The impact of radiotherapy on the success of SCT does not seem to be as essential as originally believed.

[Febrile neutropenia: practical aspects]. / Febrile Neutropenie: Praktische Aspekte.

BACKGROUND: Infections are a major cause of mortality in neutropenic patients. They require long hospital stays and highly expensive therapeutic measures. In this review we discuss the practical and pharmaco-economic aspects of the management of febrile neutropenia. PREVENTION AND THERAPY: Prevention of fever of unknown origin (FUO) demands hygienic and antimicrobiotic measures. First-line antibiotic therapy consists of an aminoglycoside combined with an ureidopenicillin or a 3rd-generation cephalosporin. Double beta-lactam antibiotic combinations are equally effective and less toxic, but more expensive. Monotherapy with carbapenems, ceftazidime, or cefepime appear to offer comparable efficacy. Lung infiltrates require immediate treatment with amphotericin B. If the initial therapeutic regime fails, a carbapenem plus a glycopeptide antibiotic and a parenteral antimycotic drug should be applied after 3 to 4 days. The prophylactic or interventional administration of hematopoietic growth factors is only indicated in special high-risk situations. CONCLUSIONS: Using the described therapeutic procedure, the response rate exceeds 90%. Consistent, step-wise escalating administration of antibiotics is essential. More evaluation is needed to determine whether selected patients with febrile neutropenia can be treated on an outpatient basis.

[Thrombocytosis in polymyalgia rheumatica]. / Die Thrombozytose bei Polymyalgia rheumatica.

BASIC PROBLEM AND OBJECTIVE OF STUDY: The diagnosis of polymyalgia rheumatica is made difficult by the absence of any pathognomonic findings. Erythrocyte sedimentation rate (ESR) and concentration of C-reactive protein are used as diagnostic criteria and to monitor the disease's course. It was the purpose of this study to evaluate prevalence of thrombocytosis and whether there is any correlation between thrombocytosis and ischaemic complications. PATIENTS AND METHODS: In a retrospective study the data of 23 patients (14 women, 9 men; mean age 67.3 [48-84] years) with polymyalgia rheumatica were analysed: platelet counts, ESR and C-reactive protein had been measured at the time of diagnosis and 7, 14 and 21 days after start of glucocorticoid treatment. At the time of diagnosis 17 of 23 patients (74%) had a thrombocytosis (> 400,000/microliter), at a mean value of 511,000 (418,000-638,000)/microliter. The platelet count decreased more slowly than the inflammatory parameters. On average the platelet count returned to normal on the 14th day. Ischaemic complications developed in three patients (visual disturbances, blindness, cardiac arrhythmias, neurological deficits): all had a high platelet count (462,000-524,000/microliter). CONCLUSIONS: Thrombocytosis can serve as an additional criterion in the diagnosis and follow-up of polymyalgia rheumatica. An association with ischaemic complications is especially likely in the elderly, in case of immobility and if there is evidence of giant-cell arteritis. Treatment with platelet aggregation inhibitors should be considered.