Precise parameter control of multicycle terahertz generation in PPLN using flexible pulse trains

The low (sub %) efficiencies so-far demonstrated for nonlinear optical down-conversion to terahertz (THz) frequencies are a primary limiting factor in the generation of high-energy, high-field THz-radiation pulses (in particular narrowband, multicycle pulses) needed for many scientific fields. However, simulations predict that far higher conversion efficiencies are possible by use of suitably-optimized optical sources. Here we implement a customized optical laser system producing highly-tunable trains of infrared pulses and systematically explore the experimental optimization of the down-conversion process. Our setup, which allows tuning of the energy, duration, number and periodicity of the pulses in the train, provides a unique capability to test predictions of analytic theory and simulation on the parameter dependences for the optical-to-THz difference-frequency generation process as well as to map out, with unprecedented precision, key properties of the nonlinear crystal medium. We discuss the agreements and deviations between simulation and experimental results which, on the one hand, shed light on limitations of the existing theory, and on the other hand, provide the first steps in a recipe for development of practical, high-field, efficiency-optimized THz sources.

Characteristic Timescales of the Local Moment Dynamics in Hund's Metals

We study the characteristic timescales of the fluctuating local moments in Hund's metal systems for different degrees of correlation. By analyzing the dynamical spin susceptibility in the real-time domain, we determine the timescales controlling oscillation and damping of on-site fluctuations-a crucial factor for the detection of local moments with different experimental probes. We apply this procedure to different families of iron pnictides or chalcogenides, explaining the material trend in the discrepancies reported between experimental and theoretical estimates of their magnetic moments.

Late spontaneous recanalization of a symptomatically occluded internal carotid artery two years after extra-intracranial bypass. Case report and review of the literature

Spontaneous recanalization of the internal carotid artery (ICA) is rarely observed. Mainly case reports are published. Most often early recanalization occurs within days or weeks and only a few cases of late recanalization months or years after detected occlusion are reported. Symptomatic bilateral ICA occlusion is regarded as an acceptable indication for extra-intracranial (EC-IC) bypass. The authors report on a case with bilateral symptomatic ICA occlusion and EC-IC bypass >2 years prior to detected spontaneous leftsided recanalization. Spontaneous recanalization unmasking a high degree ICA stenosis at the carotid bifurcation allowed a successful subsequent surgical recanalization in this patients. Mechanisms of early and late recanalization as well as treatment options are discussed.

Organ-cocultures (COCs) for long term in vitro studies of lung cancer using 2-photon microscopy

Three-dimensional organ cultures allow performing research in vitro in a complex multi-cellular environment. We aimed at developing a long term coculture system (COC) for the study of lung cancer to repeatedly measure tumor volume. Organ cultures of bronchial mucosa with 1-2 mm diameter were embedded in agarose and bisected with a tissue slicer so that the organ culture within was cut into halves uncovering the connective tissue of the stroma of each half. A cell suspension of GFP-transfected EPLC 32M1 lung tumor cells was brought in contact with the connective tissue of the wounded surface. Adherent tumor cells grew invasively into the organ culture. Using 2-Photon microscopy, Z-stacks were recorded, reconstructed with appropriate analysis software, and the tumor volume was calcvulated. Tumor cells were identified by GFP-fluorescence. Repeated measurements of the same COC could be performed over up to 8 weeks. The tumor volume increased continually with the growth rate becoming slower towards the end of culture. A comparison of two clones of tumor cells which had shown different rates of proliferation in monolayer culture demonstrated that the clone with the higher rate of proliferation in monoculture produced tumors with more rapid growth in the COC model. In this study we present a coculture system for the study of lung cancer using 2-Photon microscopy. COCs are particularly appropriate for long term in vitro treatment studies.

Ankylosing spondylitis monocytes show upregulation of proteins involved in inflammation and the ubiquitin proteasome pathway

OBJECTIVES

To determine if peripheral blood monocytes from patients with ankylosing spondylitis (AS) differed in protein expression compared to rheumatoid arthritis (RA) and healthy controls (HC).

METHODS

Monocyte protein expression was characterised by 2D gel electrophoresis and by label-free quantitative expression profiling, using nano-ultra performance liquid chromatography coupled to electrospray ionisation mass spectrometry (ESI-MS(E), where (E) refers to low/high collision energy switching). Data sets were analysed using the Waters expression profiling system and Ingenuity pathway analysis (IPA).

RESULTS

Two-dimensional gel electrophoresis showed upregulation of proteasomal constituents in AS monocytes, including the beta subunit of proteasome activator (PA)28. Monocyte expression profiling and IPA showed that significant changes in protein expression within the ubiquitin proteasome pathway (UPP) were restricted to AS monocytes. Statistically significant differences in protein expression involving the leucocyte extravasation, vascular endothelial growth factor, integrin and Toll-like receptor signalling pathways were seen in AS and RA monocytes compared to healthy controls. No evidence of upregulation of proteins involved in the endoplasmic reticulum stress response pathway was found in either AS or RA monocytes. Finally, the PA28 complex was shown to increase the generation of human leucocyte antigen (HLA)-B27 antigenic epitopes by the proteasome in vitro.

CONCLUSIONS

Our proteomic analyses support the hypothesis that monocytes play an important role in the pathogenesis of AS and RA, and further suggest a specific role in AS for the UPP. Quantitative proteomic expression profiling constitutes a powerful new tool for rheumatology research.

Cell Cycle Effects of Radiation on Human Bronchial Epithelium and Lung Carcinoma Cells in Monolayer Cultures and a Three-Dimensional Co-culture System

The aim of this study was to investigate whether the three-dimensional structure of the bronchial tissue and the contact of non-malignant with malignant cells influence the effectiveness of radiotherapy. Monolayer cultures of cells of the human bronchial epithelial cell line BEAS 2B, monolayer co-cultures of BEAS 2B cells and cells of the GFP-transfected lung carcinoma cell line EPLC 32M1, organ cultures of human bronchial epithelium, and organ co-cultures with EPLC 32M1 cells were irradiated with 10 Gy, and the DNA content was analyzed using flow cytometry. In non-malignant epithelial cells, BEAS 2B monolayer cultures without tumor cells were highly radiosensitive. However, contact with tumor cells in monolayer co-cultures markedly reduced radiosensitivity. Non-malignant cells in three-dimensional organ cultures and organ co-cultures with tumor cells showed moderate radiosensitivity. In EPLC 32M1 tumor cells, proliferation was increased without irradiation when the cells were in contact with epithelial cells in both organ and monolayer co-cultures. Radiosensitivity was higher in organ co-cultures than in monolayer cultures and monolayer co-cultures. These data indicate that organ co-cultures in combination with flow cytometry allow investigation of the effects of radiation in an in vivo-like environment and that both the spatial organization and the interaction of non-malignant and tumor cells are crucial for the effectiveness of radiotherapy.

5-Aminolevulinic acid-induced fluorescence in bronchial tumours: dependency on the patterns of tumour invasion

5-ALA-induced protoporphyrin IX (PPIX) fluorescence kinetics was quantified by fluorescence microscopy in three-dimensional organ co-cultures of human bronchial epithelium, which were infiltrated by four different lung tumour cell lines (EPLC-M31, LCLC-103H, NCI-H125 and NCI-H841). Corresponding fluorescence measurements were performed in monolayer cultures of these tumour cell lines and BEAS-2B cells as a model for normal bronchial epithelium by flow cytometry. Significant differences of fluorescence intensities (FI) between the tumours were detected in organ co-cultures as well as in single cell measurements. Relative FI values in organ co-cultures (FI(EPLC-32M1)>FI(LCLC-H103)>FI(NCI-H125)>FI(NCI-H841)) did not correspond to the measurements in single cells (FI(LCLC-H103)>FI(NCI-H125)>FI(NCI-H841)>FI(EPLC-32M1)). Histology of organ co-cultures revealed different patterns of invasion and tumour cell densities depending on the tumour type. After correction of FI in the co-cultures to tumour cell density the correlation coefficient for fluorescence values between both models increased considerably. Thus, additionally to distinctive features of 5-ALA metabolism, patterns of tumour invasion may be a factor determining 5-ALA-induced fluorescence. Considering these results, a pronounced heterogeneity of 5-ALA-induced fluorescence might be expected in different bronchial tumours in vivo. This could interfere with the diagnostic reliability of 5-ALA-induced fluorescence for early tumour detection.

[Hernia repair--which technique? Help in making the decision]

Operation of the inguinal hernia is the most common operation in general surgery. Many criteria influence the kind of operation the surgeon will perform. Detailed anatomic knowledge of the inguinal region, standardised tactical and technical performance of the operation team, careful preparation and a minimum of blood loss reduce complications to low levels. These items are the same for all operation methods. The Shouldice procedure has been the golden standard for many years, nowadays (1998) in America in more than 80% of operations a mesh is implanted in the abdominal wall. A Cochran review of EBM showed advantages for mesh repair compared to nonmesh repair. Patient oriented decision making in choosing a method for inguinal hernia repair should be the new standard of modern general surgery.

[Effectiveness and economics of private practice established surgeons, exemplified by ambulatory laparoscopic cholecystectomy in 1994 and 1996]

Ambulatory laparoscopic cholecystectomy is a safe procedure providing high patient satisfaction if performed by an experienced surgeon. These are the results of a prospective documentation of 150 outpatients to undergo laparoscopic cholecystectomy between 1994 and 1996. Patients returned to work early (mean 13.2 days off). No patient had to be admitted to hospital following ambulatory operation. All patients declared that they would have the operation performed in the same way a second time if necessary at all. Looking at the money earned for the ambulatory operation compared to the costs, there is a deficit of nearly DM 800 with each performance. Despite the good results and the great satisfaction on the part of the patients, outpatient laparoscopic cholecystectomy will not be widely performed until and unless the surgeons costs are at least covered.

[Sprain of the cervical spine: early functional vs. immobilization treatment]

Neck sprains are very common injuries often treated with immobilisation of different duration. The treatment with collars was tested against physiotherapy in a prospective randomised trial. Endpoints were defined as state of health, pain and costs. Ninety-seven patients with whiplash injuries were splitted by randomisation into two groups. One group was treated with a certain scheme of physiotherapy. Another group was treated with collar immobilisation for 3 weeks. Concerning symptoms at the time of admittance, age and sex distribution the groups were comparable. Fifty healthy persons with the same age and sex distribution served as a control group. Regarding to physical state of health and pain, which were examined by valid questionnaires, significant advantages of physiotherapy after two weeks were found. After 12 weeks the physical state of health corresponds to that of the control group. No influence on psychical state of health was seen. Physiotherapy for treatment of neck sprain is highly recommended. It has clear advantages over the treatment with collars with regard to state of health and pain, and it seems to be economically favourable.

[Ambulatory laparoscopic cholecystectomy]

A total of 140 patients underwent outpatient laparoscopic cholecystectomy in an outpatient clinic. Evaluation and follow-up of the patients were done prospectively. Population and preoperative data were comparable to published studies of patients operated on in hospitals. There were no serious intra- or postoperative complications. Postoperatively, patients needed less pain medication, were less tired and returned to work earlier than patients after clinical laparoscopic cholecystectomies. Outpatient laparoscopic cholecystectomy offers a good alternative to patients with moderate operative risks (ASA 1-3). It could reduce costs in the German health system and would be therefore highly cost effective.

Hyperinsulinism and cerebral microangiopathy

BACKGROUND AND PURPOSE

High insulin levels are a recognized risk factor for atherosclerosis. Microvascular endothelium is more susceptible to metabolic and mitogenic effects of insulin than large-vessel endothelium. Besides their atherogenic effect, high insulin levels impair fibrinolysis by enhancing plasminogen activator inhibitor-1. We undertook this study to evaluate the hypothesis that elevated serum insulin and C-peptide levels are related to cerebral small-vessel disease rather than large-vessel pathology.

METHODS

One hundred ninety-four consecutive patients presenting with symptomatic cerebrovascular disease were assigned to three subgroups that were differentiated by clinical presentations, brain imaging studies, and extracranial as well as transcranial vascular ultrasound findings: (1) patients with lacunes (n = 20), (2) patients with subcortical arteriosclerotic encephalopathy (n = 35), and (3) patients with strokes due to large-vessel disease (n = 99). Patients who had suffered a cryptogenic (n = 9) or cardioembolic (n = 16) stroke or who showed characteristics of the microangiopathy and macroangiopathy groups (n = 15) were not further evaluated. Thirty patients without manifestations of cerebrovascular disease were also examined. Fasting blood glucose, insulin, and C-peptide levels were determined in all subjects.

RESULTS

There were no significant differences in age or sex among the three groups and control patients. Insulin levels were significantly higher in the lacunar group compared with the subcortical arteriosclerotic encephalopathy group, the macroangiopathy group, and the control patients (median [interquartile range]: 103.8 [198.6], 72.0 [103.2], 66.0 [57.0], and 52.2 [57.0] pmol/L, respectively; all P < .05, Mann-Whitney test). There was a statistically significant difference in insulin concentrations between the microangiopathy group (subcortical arteriosclerotic encephalopathy and lacunes) and the macroangiopathy and control groups (81.0 [110.4], 66.0 [57.0], and 55.2 [57.0] pmol/L, respectively; all P < .05, Mann-Whitney). The same was true for the distribution of C-peptide levels and to a minor extent blood glucose values, but these differences failed to reach statistical significance.

CONCLUSIONS

Elevated insulin levels potentially represent a pathogenetic factor in the development of cerebral small-vessel disease, predominantly in patients presenting with lacunes. Whether this is due solely to atherosclerotic changes of the small penetrating arteries or whether changes in hemorheology are operative as well remains to be evaluated.

A comparison of long term results of the standard Whipple procedure and the pylorus preserving pancreatoduodenectomy

The standard Whipple procedure involves intestinal disturbances, such as dumping, diarrhea, dyspeptic complaints and the occurrence of ulcers of the anastomoses. A postoperative weight loss was observed ranging between 10 and 40 kilograms. Only a few patients were able to compensate after several months. It was thought that preservation of the intact stomach would prevent the complications arising from a loss of gastric reservoir function and thus the malnutrition could be improved postoperatively. Between 1985 and March 1992, we performed the pylorus-preserving Whipple procedure and treated a group of 43 patients with this method. In the same period, 15 patients were operated upon with the standard Whipple procedure. The present evaluation of the accumulated patient data, including extensive functional studies, led to the following results comparing the pylorus preserving Whipple procedure with the standard Whipple procedure. First, the capacity for food uptake and the development of body weight postoperatively is significantly better. Second, gastric or jejunal ulcers were not observed. Third, there were no clinical signs of digestive disorders, such as different forms of dumping. Nutrition and digestion were not impeded by the preserved opening mechanism of the pylorus. Fourth, the postoperative exocrine function was only slightly decreased. Fifth, glucose metabolism postoperatively was influenced only slightly by preservation of the pylorus. In taking the results of all the examinations into consideration, it can be said that the restricted organ loss in the Whipple procedure with pylorus preservation leaves the secretory and functional capacity of the upper part of the gastrointestinal tract almost unchanged.

Spontaneous intracerebral hemorrhage following carotid endarterectomy. Experience of 328 operations from 1983-1988

In a consecutive series of 328 carotid endarterectomies there were two cases of postoperative intracerebral hemorrhage. The patients with transient ischemic attacks and subsequent major cerebral infarction had repair of their very tight carotid stenosis. Each developed intracerebral hemorrhage after a symptom free interval and hypertension was uncontrolled during the postoperative period. Hypertension is a significant complication of carotid endarterectomy and may be a prominent factor in the development of intracerebral hemorrhage after carotid endarterectomy. Also defective cerebrovascular autoregulation in chronic ischemic brain regions may predispose patients to intracerebral hemorrhage.

Akuter schmerz in der chirurgie die bedeutung eines vernachl�ssigten problems

Acute pain represents a significant problem in surgical patients. However, the management of acute pain in Germany is unsatisfactory, mostly because surgeons are not interested in the pain of their patients, and anesthesiologists do not give pain treatment on surgical wards. The aim of this article is therefore to point out the significance of the problem of "acute pain" for surgeons. Basic knowledge of the production, perception and projection of pain as well as the special aspects of acute versus chronic pain is mandatory. Every surgeon should know about the predictors of postoperative pain, including the surgical and anesthesiological factors and patient characteristics. Efficient management of acute pain requires knowledge of the clinical significance of pain and the different methods for assessment. It is not sufficient to know the methods and advantages of appropriate management of acute pain; one must also understand the dangers. Problems caused by the treatment of pain should be recognized from a clinical point of view. Surgeons must take a greater interest in the problem of "pain", which should lead to the establishment of new concepts in the management of acute pain in surgical patients.

Thromboembolieprophylaxe mit niedermolekularem Heparin in der Chirurgie

In einer Multicenter-Studie mit insgesamt 2428 Patienten an 85 Kliniken der Bundesrepublik wurden klinische Wirksamkeit und Verträglichkeit der Thromboembolieprophylaxe mit dem niedermolekularen Heparin Fraxiparin untersucht. Die Mehrzahl der Patienten kam aus dem Bereich der Allgemeinchirurgie (N = 2037), zusätzlich wurden 222 gefäßchirurgische Eingriffe und 125 gynäkologische Operationen durchgeführt. Den Patienten wurde einmal pro Tag eine subkutane Injektion von 0,3 ml Fraxiparin verabreicht.

Postoperativ wurden in der klinischen Studie neun Verdachtsdiagnosen und drei apparativ bestätigte Diagnosen einer Lungenembolie gestellt. Dagegen wurde nur eine klinisch manifeste tiefe Venenthrombose diagnostiziert.

Die untersuchten Kriterien der Verträglichkeit zeigten keine wesentlichen Abweichungen zu den bisher durchgeführten Studien hinsichtlich der Parameter intraund postoperativer Blutverlust, Wundhämatome und Reoperationen bei Blutungskomplikationen. Der Einsatz von niedermolekularem Heparin (Fraxiparin) bietet bei einmal täglicher Applikation einen ausreichend hohen antithrombotischen Schutz.

[Prevention of stress-induced hemorrhage of the upper gastrointestinal tract in neurosurgical intensive care patients. A controlled, randomized double-blind study with ranitidine alone and in combination with pirenzepine]

During a controlled, randomized, double blind study, 30 patients of a neurosurgical intensive care unit were treated with ranitidin and placebo (group 1) or ranitidin and pirenzepin (group 2). No significant difference in the effectivity of both methods was established, presumably due to the small number of cases. The pH values of group 2 lay in the median above 3.5, whereby the difference only became statistically significant after a seven-day period of therapy. In how far the increase of the pH value represents the only factor of a stress ulcer prophylaxis requires further investigation, particularly in connection with pulmonary risks caused by this.

Treatment of abdominothoracic actinomycosis with imipenem

The probably successful treatment of a 42 year old diabetic patient suffering from relapsing abdominothoracic actinomycosis with imipenem is reported. Several earlier attempts to cure the patient by combination of surgical procedures (including cysto-jejunostomy and pancreatic tail resection) in combination with four or six week courses of intravenously administered penicillin G had failed.

Formation of cysteinyl-containing leukotrienes by human arterial tissues

Human arterial rings incubated in modified Tyrode solution released small amounts of leukotriene (LT) C4-like material spontaneously and larger amounts upon stimulation with the ionophore A23187 as determined by radioimmunoassay. By reversed phase high pressure liquid chromatography (HPLC) LTC4-like material was found to comigrate with authentic LTC4, LTD4 and LTE4. Nordihydroguaiaretic acid (NDGA) significantly inhibited the ionophore A23187-induced release of LTC4-like material, while indomethacin was without effect. Simultaneously the arterial rings released much larger amounts of 6-keto-prostaglandin (PG) F1 alpha, which were significantly decreased by indomethacin. The results demonstrate that human arterial tissue has the capacity to synthesize cysteinyl-containing LT from endogenous arachidonic acid.

An enzymatic assay for monitoring serum, cerebrospinal fluid, and urine concentration of beta-lactam antibiotics

August 29/October 24, 1984 An enzymatic assay for the determination of the concentrations of various beta-lactam antibiotics in serum, urine, and cerebrospinal fluid samples is described. Recently developed beta-lactam derivatives are used as competitive inhibitors of the breakdown of the labile coloured beta-lactam compound PADAC, which serves as the substrate for the various beta-lactamases. Under the conditions of the assay, there is effectively no interference due to the matrix. Moreover, the assay is not influenced by other antibiotics such as aminoglycosides, macrolides, ansamycines, tetracyclines, fusidic acid or fosfomycin. The C.V.s for within-run precision ranged from 3.7% to 4.4%, depending on the beta-lactam derivative. The sensitivity of the assay is at least comparable with that of conventional procedures. Excellent correlations were observed between the enzymatic and the microbiological procedures; correlation coefficients: r = 0.988 for 22 imipenem samples, r = 0.968 for 16 cefotaxime samples, and r = 0.989 for 16 piperacillin samples routinely sent to our laboratory.

[Aneurysm of the internal carotid artery at the base of the skull (author's transl)]

A 15-year-old diabetic boy suffering from recurrent peritonsillar infections developed a mycotic aneurysm of the internal carotid artery at the base of the skull. The aneurysm was approached through a cervical and retroauricular incision. The styloid process was burred down at its base. The sternocleidomastoid muscle and the digastric muscle were resected from the mastoid. The internal carotid artery was clamped proximally and blocked with a balloon-catheter distally. The carotid bone canal was opened 10 mm and the carotid artery resected until normal vessel wall was reached. A vein graft was placed end-to-end with single stitches, using 8 X 0 monofil sutures with a small needle. The postoperative course was uneventful except for a temporary paresis of the peripheral facial nerve. Postoperative angiography revealed restoration of the vessel to normal, the patient is now free of symptoms.