Versatile optical laser system for experiments at the European X-ray free-electron laser facility.

We present the main features of the final prototype of a pulsed optical laser, developed for pump-probe and other experiments in conjunction with the femtosecond x-ray beams at the European X-ray free-electron laser facility. Adapted to the temporal x-ray emission pattern of the facility, the laser provides 10 Hz bursts of up to 600 µs duration with intra-burst pulse frequencies as high as 4.5 MHz. In this mode, we have generated pulses as short as 12 fs at 350 W average power during the burst and with beam qualities close to the diffraction limit. This is, to the best of our knowledge, the highest power to date of a few-cycle laser operating at a center wavelength of 800 nm. Important for experimental flexibility, the laser can be configured in various unique ways, enabling, e.g., energy scaling to >3 mJ per pulse through a frequency change down to 100 kHz and the generation of nearly transform limited pulses between 12 fs and 300 fs. In addition to the 800 nm femtosecond beam line, a synchronized long pulse (0.8 ps or 400 ps) 1030 nm beam can be utilized, offering up to 4 kW burst average power, i.e. up to 40 mJ per pulse at 100 kHz. Efficient nonlinear wavelength conversion and tuning through intrinsic and external means further enhance the capabilities of the laser.

Absorption, disposition and metabolism of di-isononyl phthalate (DINP) in F-344 rats.

Di-isononyl phthalate (DINP; CAS no. 68515-48-0) is a general-purpose plasticizer for polyvinyl chloride. It produced liver and kidney effects when given to rodents at high oral doses, but there were no target organ effects in primates treated under similar conditions. To assist in understanding the basis for these species differences, the pharmacokinetic properties of DINP were evaluated in rodents following both oral and dermal administration. These studies demonstrated that the pharmacokinetic properties of DINP are similar to those of other high-molecular-weight phthalates. When orally administered to rodents, DINP is rapidly metabolized in the gastrointestinal tract to the corresponding monoester, absorbed and excreted, primarily in the urine. Shortly after administration, DINP is found primarily in liver and kidneys, but it does not persist or accumulate in any organ or tissue. It is very poorly absorbed from the skin, but once absorbed it behaves in the same way as the orally administered material. The results of these rodent studies contrast with data from studies involving humans or other primates, which indicate low absorption at low oral doses and much more limited total absorption at high doses. It appears that many, if not all, of the effects of DINP in rodent studies are associated with internal doses that would be difficult, if not impossible, to achieve in humans under any circumstances. Thus, the results of rodent studies may not be very useful in assessing the potential risks to humans from high-molecular-weight phthalates.

Cerebral blood flow in the diabetic patient.

Diabetes is a major risk factor for cardiovascular disease. Coronary revascularization utilizing cardiopulmonary bypass (CPB) is frequently required for the diabetic patient. Nondiabetic individuals can autoregulate cerebral blood flow (CBF) through metabolic and perfusion pressure mechanisms during CPB. However, it has been reported that diabetic patients have impaired CBF autoregulation during CPB. It is possible, therefore, that impaired CBF autoregulation may contribute to postoperative neuropsychologic dysfunction. The mechanisms for this defect may reside in impaired endothelial-dependent responses in the diabetic that are related to morphological and functional changes linking the vascular endothelium and the vascular smooth muscle. The morphological changes occurring in the diabetic include microangiopathy and macroangiopathy which are characterized by endothelial cell (EC) hyperplasia and basement membrane thickening. Also, significant functional changes in local control of vascular tone, such as an imbalance in the synthesis and secretion of vasoactive factors by the EC and abnormal reactivity of the vascular smooth muscle, are seen in the diabetic when compared to the nondiabetic. More specifically, vascular responses to both calcium-dependent pathways of vasoconstriction and nitric oxide pathways of vasorelaxation have been shown to significantly differ between the diabetic and nondiabetic. The emphasis of this discussion is to examine the molecular mechanisms by which diabetes alters vascular function, with emphasis placed on regulation of cerebral artery blood flow during CPB.

Lyme disease presenting as isolated acute urinary retention caused by transverse myelitis: an electrophysiological and urodynamical study.

Several neurological manifestations of Lyme disease, both central and peripheral, have been described. Reported here is a case of acute transverse myelitis related to a Lyme neuroborreliosis that presented with isolated acute urinary retention and no lower-extremity impairment. This case, documented by urodynamic and electrophysiological investigations, partially resolved after 6 weeks of intravenous ceftriaxone, affording the removal of the indwelling catheter. Alpha blocker therapy was needed for 3 months, until the complete normalisation of urodynamic and electrophysiological records. This case study indicates that whenever urinary retention is encountered associated with acute transverse myelitis or alone, the patient should be investigated for Lyme disease.

Pancreatic metabolism of benzo(a)pyrene in vitro and in vivo in the Long-Evans rat.

The in vitro metabolism of benzo(a)pyrene was compared between pancreas and liver with and without pretreatment. There was no significant difference in metabolic pathways between the two tissues. Evidence for induction of the metabolism was evident following 3-methyl-cholanthrene pretreatment. Temporal studies demonstrated rapid elimination of BP from the tissues within the first 5 hours with possible recirculation of metabolites 22 hours after injection of the carcinogen. There was significant binding of BP to DNA in pancreas and liver at 5 hours.