DEADSPACE IN PAEDIATRIC ANAESTHETIC APPARATUS

The effective apparatus deadspace of the Magill, Potter andCape Town gas circuits has been investigated using a model systemsimulating 3- and 8-year-old children. The Cape Town system is more suitable for smaller children. The Potter system is more suitable for larger children. A generous fresh gas flow will decrease the deadspace of thePotter and the Cape Town systems. A flow of double the minutevolume is suggested. There is no place for the Magill system in anaesthesia of children,and it might be better to supplant it with the Potter systemin adults too.     

Information processing and coping style during the wake/sleep transition

Information processing of meaningful events (subject's own name, neutral name and tones) was studied during the transition from wakefulness to sleep in two groups of subjects with opposing information processing styles, Monitors and Blunters. In two experimental sets, subjects were instructed to execute a fingerlift response to a predetermined stimulus type. Subject's own name produced the greatest number of K-complexes and arousals relative to other name and tones. A task relevance effect was found for arousals but not for K-complexes. The overall P3 amplitude was larger for Monitors than for Blunters, whereas Blunters showed a larger N350 to target stimuli than Monitors. The findings suggest that higher level processing continues during light sleep and that N350 may reflect a process related to sleep maintenance.     

What Range of Programmable AV Delays is Necessary in Antibradycardia DDD Stimulation?

DDD pacemakers differ considerably in device specific extents of AV delay (AVD) programmability. To demonstrate the requirements of a mean DDD pacemaker patient population optimal AVDs in 200 DDD pacemaker patients (age 8 to 91 years) were estimated by left atrial electrography. The results should help to define an AVD programmability standard. Left atrial electrograms were recorded via a bipolar filtered esophageal lead. The method aims on adjusting the left atrial electrogram to 70 ms prior to the ventricular spike, both during VDD and DDD operation of the pacemaker. In atrial sensed stimulation the optimal AVD varied from 40 to 205 ms (100.5 ± 24.5 ms) and in atrial paced stimulation from 85 to 245 ms (169.1 ±24.5 ms). The difference of the mean values is statistically significant (p < 0.001). The difference between both values in the individual patient, the individual AVD correction time, varied from 0 to 170 ms (68.7 ± 26.6 ms). Thus, from our findings requirements on AV delay programmability standard can be derived: AVDs (1) should have a range from 40 to 250 ms, (2) should be independently programmable during atrial sensed and atrial paced operation, ami (3) should provide as nominal settings 100 ms for atrial sensed and 170 ms for atrial paced stimulation.     

Homing of transplanted bone marrow cells in livers of Schistosoma mansoni‐infected mice

Elkhafif N, Voss B, Hammam O, Yehia H, Mansy S, Akl M, Boehm S, Mahmoud S, El Bendary O, El Fandy G. Homing of transplanted bone marrow cells in livers of Schistosoma mansoni‐infected mice. APMIS 2010; 118: 277–87. The efficiency of differentiation of bone marrow cells (BMCs) into hepatocytes in vivo and its importance in physiopathological processes is still debated. Murine schistosomiasis was used as a liver injury model and unfractionated male mice BMCs were transplanted through intrahepatic injection into non‐irradiated Schistosoma mansoni‐infected female mice on their 16th week post‐infection. Two weeks after bone marrow transplantation, mice were sacrificed on a weekly basis until 10 weeks. Tracing of male donor‐derived cells in female recipient mice livers was carried out by the detection of Y chromosome expression by fluorescent in situ hybridization (FISH) and also of chromodomain Y‐linked (CDYL) protein by indirect immunofluorescence (IF). Their transformation into hepatocytes was studied by double labelling indirect IF using antibodies directed against CDYL and mouse albumin. Histopathological and electron microscopic examinations revealed the presence of small hepatocyte‐like cells in the periportal tracts and in between the hepatocytes facing the sinusoids. Donor‐derived cells showing Y chromosome by FISH and expressing CDYL protein by IF were recovered in the infected transplanted livers. The initial number of these cells increased with increased post‐transplantation time. Cells were mainly localized in the periphery of schistosoma granuloma. Few donor‐derived cells appeared within the hepatic parenchymal tissue and showed positivity for albumin secretion by double labelling with IF. We suggest that transplanted bone marrow stem cells can repopulate the Schistosoma‐infected liver of immunocompetent mice. Their differentiation is a complex event controlled by many factors and needs to be further characterized extensively. The extent and type of liver injury and the number of transplanted cells are important variables in the process of stem cell engraftment and differentiation into functioning hepatic cells that still need to be defined.