Photolysis of CF3CH2CHO in the presence of O2 at 248 and 266 nm: quantum yields, products, and mechanism.

Three different detection techniques, coupled to pulsed laser photolysis (PLP), have been employed to determine the quantum yields of CF3CH2CHO at 248 and 266 nm: CF3CH2CHO + hν → CF3CH2 + HCO (R1a), CF3CH2CHO + hν → CF3CH3 + CO (R1b), and CF3CH2CHO + hν → CF3CH2O + H (R1c). (a) In the presence of air, Fourier transform infrared (FTIR) spectroscopy was employed at a total pressure of 760 Torr to monitor and quantify the loss of CF3CH2CHO at both wavelengths as well as the build-up of formed products (CO, CF3CH3, CF3CHO, and CF3CH2OH) after various laser pulses. Cyclohexane was added as OH-scavenger in most experiments. CF3CH3 was observed and quantified at both wavelengths, confirming that channel R1b is occurring. Small amounts of HCOOH and COF2 were also detected. (b) Time-resolved cw-cavity ring down spectroscopy (cw-CRDS) at 40 Torr He coupled to photolysis at 248 nm was employed for the detection of HO2 radicals. Varying the O2 concentration allows distinguishing the origin of the HO2 radicals from either R1a or R1c. OH radicals were simultaneously detected by laser-induced fluorescence. (c) Time-resolved tunable diode laser absorption spectroscopy (TDLAS) at 30 Torr N2 coupled to photolysis at 266 nm was employed for the determination of the quantum yields of CO. By varying the O2 concentration, a distinction can be achieved between the yields of prompt CO R1b or decomposition of highly excited CF3CH2CO from R1c and HCO radicals R1a. Channel R1a has been identified as the major reaction path. The overall quantum yield, Φλ(CF3CH2CHO), at 248 nm was found as Φ248nm = (0.76 ± 0.14) and (0.73 ± 0.20) from cw-CRDS and FTIR experiments, respectively. At 266 nm, the overall quantum yield was found as Φ266nm = (0.55 ± 0.10) and (0.47 ± 0.10) from TDLAS and FTIR experiments, respectively.

Sensorimotor polyneuropathy in light chain multiple myeloma.

The authors describe an adult onset sensorimotor polyneuropathy in a woman with light chain K-type myeloma. Neurophysiological investigation showed a severe reduction of conduction velocity of the peripheral nerve to the four limbs. A muscle and sural nerve biopsy were performed. Sural nerve displayed a severe loss of myelinated and unmyelinated fibers. No amyloid deposit was observed in vessels, perineurium and endomysium by electron microscopy examination. No onion bulb formation was present in nerve tissue, but many demyelinated fibers were surrounded by circumferentially disposed Schwann cell processes without any interposition of collagen fibrils. Some fibers exhibit signs of active remyelination; axonal alterations were rarely seen. Collagen pockets were frequently observed among proliferated collagen fibrils. The mechanism of peripheral nerve lesions in various categories of multiple myeloma is till now an unsolved problem. In this case the unusual association with a light chain myeloma suggest that these immunoglobulins play a role in the pathogenesis of the polyneuropathy as supported by experimental studies.

Hernias paraesofagicas: experiencia de dos anos / Paraesophageal hernias: a 2 years experience

Se comenta una serie de 6 casos de hernias diafragmaticas paraesofagicas observadas en un total de 720 consultas por trastornos digestivos (0,8%). Todos los casos pertenecian al sexo femenino; 5 presentaron sintomas digestivos y 1 era asintomatica. La endoscopia no revelo esofagitis. Coexistian con la hernia una litiasis vesicular y un cancer del antro pilorico.Estas fueron las unicas enfermas operadas; se efectuo colecistectomia y gastrectomia Billroth II, agregandose en ambos la reduccion de la hernia, cierre parcial del hiato y procedimiento de Nissen. Una enferma recidivo; fue reoperada, colocandose una plastica con Marlex. Las otras 4 pacientes evolucionaron bien con tratamiento medico

Hernias paraesofagicas: experiencia de dos anos / Paraesophageal hernias: a 2 years' experience

Se comenta una serie de 6 casos de hernias diafragmaticas paraesofagicas observadas en un total de 720 consultas por trastornos digestivos (0,8%). Todos los casos pertenecian al sexo femenino; 5 presentaron sintomas digestivos y 1 era asintomatica. La endoscopia no revelo esofagitis. Coexistian con la hernia una litiasis vesicular y un cancer del antro pilorico.Estas fueron las unicas enfermas operadas; se efectuo colecistectomia y gastrectomia Billroth II, agregandose en ambos la reduccion de la hernia, cierre parcial del hiato y procedimiento de Nissen. Una enferma recidivo; fue reoperada, colocandose una plastica con Marlex. Las otras 4 pacientes evolucionaron bien con tratamiento medico