Towards ten-watt-level 3-5 µm Raman lasers using tellurite fiber.

Raman lasers based on mid-infrared fibers operating at 3-5 µm atmospheric transparency window are attractive sources for several applications. Compared to fluoride and chalcogenide fibers, tellurite fibers are more advantageous for high power Raman fiber laser sources at 3-5 µm because of their broader Raman gain bandwidth, much larger Raman shift and better physical and chemical properties. Here we report on our simulations for the development of 10-watt-level 3-5 µm Raman lasers using tellurite fibers as the nonlinear gain medium and readily available continuous-wave (cw) and Q-switched erbium-doped fluoride fiber lasers at 2.8 µm as the pump sources. Our results show that a watt-level or even ten-watt-level fiber laser source in the 3-5 µm atmospheric transparency window can be achieved by utilizing the 1st- and 2nd-order Raman scattering in the tellurite fiber. The presented numerical study provides valuable guidance for future 3-5 um Raman fiber laser development.

Etiopathology of Arnold-Chiari malformation: a fetal rat model of dysraphism.

OBJECTIVES: We report an experimental fetal rat model with the aim of comparing two surgical methods used to check Arnold-Chiari Malformation (ACM) by dysraphism. We also wanted to (1) determine which type(s) of ACM akin to human anatomical findings were generated with the model and (2) study whether a cerebrospinal fluid pressure gradient could be responsible for ACM's etiopathology. MATERIALS AND METHODS: At E20, a mean of two fetuses per pregnant rat underwent an incision at the 2-3 lumbar level, deep into the medulla oblongata central canal, by two different surgical methods. Cesarian section was performed at E22. Dysraphic fetuses were examined clinically. Those born alive and controls without lesions were anatomically and histologically studied. RESULTS: Method 2 was better than method 1 at reproducing the model. 100% of operated fetuses showed no spontaneous motility or sensibility to pressure on the posterior limbs in addition to anatomopathological evidence of type II ACM. CONCLUSIONS: A high rate of ACM could be checked by dysraphism with both methods. The opening of the central canal was demonstrated to generate a cerebrospinal fluid pressure gradient responsible for the herniation of encephalic structures comparable with human ACM. We believe this model may be useful for evaluating further strategies for prenatal treatment.

Dietary deficiency or enrichment of essential fatty acids modulates tumorigenesis in the whole body of cobalt-60-irradiated mice.

The effect of dietary polyunsaturated fatty acids (PUFAs) on whole body-induced tumorigenesis was assayed in mice fed on essential fatty acid sufficient (EFAS) or essential fatty acid deficient (EFAD) diets following cobalt-60 irradiation. Four groups of mice were maintained, one on a control stock diet and three on experimental diets: a) without added fat (fat free, FF); b) containing 5% olein (O), rich in n-9; and c) containing 5% corn oil, rich in n-6 EFA (CO). Only mice fed on FF or O diets showed clinical and biochemical signs of EFAD. Total incidence of tumors showed an increase in FF (P < 0.02) and O (P < 0.03) mice. Tumors developed mostly in the liver in each of the EFAD groups (P < 0.001). Slight promoting activity on lung tumorigenesis was recorded in the CO group when this parameter was compared in EFAD and EFA sufficient mice. It may be concluded that, when a tumor initiator injures the body as a whole, EFAD, achieved either through a fat-free or an oleic-supplemented diet, behaves as a general promoting condition for tumorigenesis. The borderline tumorigenic effect of n-6 corn oil on the lungs suggests that this effect, when present, is target specific.

Spontaneous murine lung adenocarcinoma (P07): A new experimental model to study paraneoplastic syndromes of lung cancer.

We report the histological and biological behavior characteristics of a lung tumor (P07) that arose spontaneously in a Balb/c mouse. P07 is a moderately to poorly differentiated adenocarcinoma that secretes granulocyte-macrophage colony stimulating factor (GM-CSF) in culture supernatants. This tumor presents some paraneoplastic syndromes, such as leukocytosis, hypercalcemia and cachexia. taken together with the peripheral blood leukocyte (PBL) counts and serum calcium levels during s.c. tumor growth and after surgery, this study suggests that P07 may be a useful experimental model to study the biology of lung cancer and paraneoplastic syndromes.