Generation, characterization, and medical utilization of laser-produced emission continua

Intense continua of electromagnetic radiation of very brief duration are formed in the interaction of focused ultra-short terawatt laser pulses with matter. Two different kinds of experiments, which have been performed utilizing the Lund 10 Hz titanium-doped sapphire terawatt laser system are being described, where visible radiation and X-rays, respectively, have been generated. Focusing into water leads to the generation of a light continuum through self-phase modulation. The propagation of the light through tissue was studied addressing questions related to optical mammography and specific chromophore absorption. When terawatt laser pulses are focused onto a solid target with high nuclear charge Z, intense X-ray radiation of few ps duration and with energies exceeding hundreds of keV is emitted. Biomedical applications of this radiation are described, including differential absorption and gated-viewing imaging

Early neoplastic and metastatic mammary tumours of transgenic mice detected by 5-aminolevulinic acid-stimulated protoporphyrin IX accumulation

A photodynamic technique for human breast cancer detection founded upon the ability of tumour cells to rapidly accumulate the fluorescent product protoporphyrin IX (PpIX) has been applied to transgenic mouse models of mammary tumorigenesis. A major goal of this investigation was to determine whether mouse mammary tumours are reliable models of human disease in terms of PpIX accumulation, for future mechanistic and therapeutic studies. The haeme substrate 5-aminolevulinic acid (5-ALA) (200 mg kg−1) was administered to mouse strains that develop mammary tumours of various histological subtypes upon expression of the transgenic oncogenes HRAS, Polyoma Virus middle T antigen, or Simian Virus 40 large T antigen in the mammary gland. Early neoplastic lesions, primary tumours and metastases showed consistent and rapid PpIX accumulation compared to the normal surrounding tissues, as evidenced by red fluorescence (635 nm) when the tumours were directly illuminated with blue light (380–440 nm). Detection of mouse mammary tumours at the stage of ductal carcinoma in situ by red fluorescence emissions suggests that enhanced PpIX synthesis is a good marker for early tumorigenic processes in the mammary gland. We propose the mouse models provide an ideal experimental system for further investigation of the early diagnostic and therapeutic potential of 5-ALA-stimulated PpIX accumulation in human breast cancer patients

Quadrature error estimates for layer potentials evaluated near curved surfaces in three dimensions

The quadrature error associated with a regular quadrature rule for evaluation of a layer potential increases rapidly when the evaluation point approaches the surface and the integral becomes nearly singular. Error estimates are needed to determine when the accuracy is insufficient and a more costly special quadrature method should be utilized. The final result of this paper are such quadrature error estimates for the composite Gauss-Legendre rule and the global trapezoidal rule, when applied to evaluate layer potentials defined over smooth curved surfaces in R3. The estimates have no unknown coefficients and can be efficiently evaluated given the discretization of the surface, invoking a local one-dimensional root-finding procedure. They are derived starting with integrals over curves, using complex analysis involving contour integrals, residue calculus and branch cuts. By complexifying the parameter plane, the theory can be used to derive estimates also for curves in R3. These results are then used in the derivation of the estimates for integrals over surfaces. In this procedure, we also obtain error estimates for layer potentials evaluated over curves in R2. Such estimates combined with a local root-finding procedure for their evaluation were earlier derived for the composite Gauss-Legendre rule for layer potentials written in complex form [4]. This is here extended to provide quadrature error estimates for both complex and real formulations of layer potentials, both for the Gauss-Legendre and the trapezoidal rule. Numerical examples are given to illustrate the performance of the quadrature error estimates. The estimates for integration over curves are in many cases remarkably precise, and the estimates for curved surfaces in R3 are also sufficiently precise, with sufficiently low computational cost, to be practically useful

Dopamine-related receptors, substance dependence, behavioral problems and personality among juvenile delinquents

The objective was two-fold: to examine possible associations between dopamine-related genetic polymorphisms and (1) substance dependence; and (2) self-reported psychiatric disturbances, behavioral problems, and personality. Genotyping of single nucleotide polymorphisms (SNP: s) in COMT, DAT and DRD4 was conducted in 174 Russian male juvenile inmates (14–18 years of age) subdivided into having a diagnosis of substance dependence or not, as assessed by using K-SADS-PL. The inmates completed several self-reports assessing psychiatric symptoms (CPTS-RI, BDI), behavioral problems (YSR), and personality traits (TCI). Results revealed that juveniles meeting the criteria for substance dependence differed significantly from their counterparts in four polymorphisms, namely COMT rs737865, DAT rs6347, DRD4 C_1611535 and DRD4 exon III; and exact binary regression analysis indicated a highly significant association between the DRD4 C_1611535 GG genotype and substance dependence. One-way ANOVA tests further showed this gene polymorphism variant to be significantly associated with higher levels of posttraumatic stress, thought problems, aggressive behavior, and personality traits indicating antisocial personality disturbances, as compared with the other gene polymorphism variants. In conclusion, the results underscore the role of the DRD4 polymorphism C_1611535 GG genotype for substance dependence, and suggest its associations with different self-reported phenotype characteristics