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Hellman, Amy N.,Vahidi, Behrad,Kim, Hyung Joon,Mismar, Wael,Steward, Oswald,Jeon, Noo Li,Venugopalan, Vasan Royal Society of Chemistry 2010 Lab on a chip Vol.10 No.16
<P>We describe the integrated use of pulsed laser microbeam irradiation and microfluidic cell culture methods to examine the dynamics of axonal injury and regeneration <I>in vitro</I>. Microfabrication methods are used to place high purity dissociated central nervous system neurons in specific regions that allow the axons to interact with permissive and inhibitory substrates. Acute injury to neuron bundles is produced <I>via</I> the delivery of single 180 ps duration, λ = 532 nm laser pulses. Laser pulse energies of 400 nJ and 800 nJ produce partial and complete transection of the axons, respectively, resulting in elliptical lesions 25 μm and 50 μm in size. The dynamics of the resulting degeneration and regrowth of proximal and distal axonal segments are examined for up to 8 h using time-lapse microscopy. We find the proximal and distal dieback distances from the site of laser microbeam irradiation to be roughly equal for both partial and complete transection of the axons. In addition, distinct growth cones emerge from the proximal neurite segments within 1–2 h post-injury, followed by a uniform front of regenerating axons that originate from the proximal segment and traverse the injury site within 8 h. We also examine the use of EGTA to chelate the extracellular calcium and potentially reduce the severity of the axonal degeneration following injury. While we find the addition of EGTA to reduce the severity of the initial dieback, it also hampers neurite repair and interferes with the formation of neuronal growth cones to traverse the injury site. This integrated use of laser microbeam dissection within a micropatterned cell culture system to produce precise zones of neuronal injury shows potential for high-throughput screening of agents to promote neuronal regeneration.</P> <P>Graphic Abstract</P><P>We describe the integrated use of pulsed laser microbeam irradiation and microfluidic cell culture to examine the dynamics of axonal injury and regeneration <I>in vitro</I>. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b927153h'> </P>
S. HELLMAN,M. UDDIN,P. T. TKACIK,S. D. KELLY 한국자동차공학회 2016 International journal of automotive technology Vol.17 No.2
The performance and safety of the rear wing and spoiler employed on the National Association of Stock Car Auto Racing (NASCAR) COT (car of tomorrow) racecar are experimentally studied using 10 % scale models in a water channel. Particle image velocimetry is used to qualitatively examine the differences in flow structures between the two downforce-generating devices under 0 and 180-degree yaw cases. The latter is important due to an issue with the COT flipping into the air when at extreme yaw (i.e. during a crash). At zero yaw, it is observed that smaller length scales of the flow structures in the wake of the wing compared to those in the wake of the spoiler, provide more predictable handling for racecars in close proximity and may allow more safe and competitive racing. At 180-degree yaw, it is observed that wake-structure interactions may not allow proper operation of anti-flipping devices (roof flaps) on the winged car. In the extreme yaw case, local flow scales are examined and show much stronger Reynolds number (Re) dependence for the wing than the spoiler.
Yeast Elf1 Factor Is Phosphorylated and Interacts with Protein Kinase CK2
Kubinski, Konrad,Zielinski, Rafal,Hellman, Ulf,Mazur, Elzbieta,Szyszka, Ryszard Korean Society for Biochemistry and Molecular Biol 2006 Journal of biochemistry and molecular biology Vol.39 No.3
One of the biggest group of proteins influenced by protein kinase CK2 is formed by factors engaged in gene expression. Here we have reported recently identified yeast transcription elongation factor Elf1 as a new substrate for both monomeric and tetrameric forms of CK2. Elf1 serves as a substrate for both the recombinant CK2$\alpha$' ($K_m$ 0.38 ${\mu}M$) and holoenzyme ($K_m$ $0.13\;{\mu}M$). By MALDI-MS we identified the two serine residues at positions 95 and 117 as the most probable in vitro phosphorylation sites. Co-immunoprecypitation experiments show that Elf1 interacts with catalytic ($\alpha$ and $\alpha$') as well as regulatory ($\beta$ and $\beta$') subunits of CK2. These data may help to elucidate the role of protein kinase CK2 and Elf1 in the regulation of transcription elongation.
Cervical cancer in the screening era: who fell victim in spite of successful screening programs?
B. Folke Pettersson,Kristina Hellman,Roxane Vaziri,Sonla Andersson,Ann-Cathrin Hellström 대한부인종양학회 2011 Journal of Gynecologic Oncology Vol.22 No.2
Objective: To compare profiles of a prescreening and screening cohort of women with cervical cancer regarding histopathology and clinical variables in order to identify those remaining at risk despite successful screening programs. By analyzing these profiles we hope to improve future screening methods. Methods: The prescreening and screening cohorts consisted of 5,046 and 1,174 women, respectively, treated for cervical cancer at the Department of Gynecological Oncology at Radiumhemmet, Karolinska University Hospital, during the periods 1944-1957 and 1990-2004. Results: Mean age increased from 48.9 years to 55.3 years in the cohorts treated 1944-1957 and 1990-2004, respectively. The percentage of patients older than 69 years was 5.4% and 27.3% in the prescreening and screening period, respectively. A shift towards earlier stages at diagnosis, a reduction of squamous cervical cancer and an increase of adenocarcinoma were observed in the screening cohort. The percentage of adenocarcinoma was about 6 times higher among younger patients. Cases of stump cancer and cervical cancer associated with pregnancy have declined. Eighty-seven women in the screening cohort had a history of treatment for in situ carcinoma by conization; 28% of these cases developed cervical cancer within one year after conization. Conclusion: The profile changed in the screening era indicating a need to refine screening for improved detection of in older women. This study, one of the largest clinical series of cervical cancer, provides an important baseline with which later studies can be compared to evaluate the effects of human papillomavirus vaccine and other important changes in this field. Objective: To compare profiles of a prescreening and screening cohort of women with cervical cancer regarding histopathology and clinical variables in order to identify those remaining at risk despite successful screening programs. By analyzing these profiles we hope to improve future screening methods. Methods: The prescreening and screening cohorts consisted of 5,046 and 1,174 women, respectively, treated for cervical cancer at the Department of Gynecological Oncology at Radiumhemmet, Karolinska University Hospital, during the periods 1944-1957 and 1990-2004. Results: Mean age increased from 48.9 years to 55.3 years in the cohorts treated 1944-1957 and 1990-2004, respectively. The percentage of patients older than 69 years was 5.4% and 27.3% in the prescreening and screening period, respectively. A shift towards earlier stages at diagnosis, a reduction of squamous cervical cancer and an increase of adenocarcinoma were observed in the screening cohort. The percentage of adenocarcinoma was about 6 times higher among younger patients. Cases of stump cancer and cervical cancer associated with pregnancy have declined. Eighty-seven women in the screening cohort had a history of treatment for in situ carcinoma by conization; 28% of these cases developed cervical cancer within one year after conization. Conclusion: The profile changed in the screening era indicating a need to refine screening for improved detection of in older women. This study, one of the largest clinical series of cervical cancer, provides an important baseline with which later studies can be compared to evaluate the effects of human papillomavirus vaccine and other important changes in this field.
Chacon-Heszele, Maria F.,Zuo, Xiaofeng,Hellman, Nathan E.,McKenna, Sarah,Choi, Soo Young,Huang, Liwei,Tobias, John W.,Park, Kwon Moo,Lipschutz, Joshua H. American Physiological Society 2014 American Journal of Physiology Vol.306 No.9
<P>Cystogenesis and tubulogenesis are basic building blocks for many epithelial organs, including the kidney. Most researchers have used two-dimensional (2D) cell culture to investigate signaling pathways downstream of hepatocyte growth factor (HGF). We hypothesize that three-dimensional (3D) collagen-grown Madin-Darby canine kidney (MDCK) cells, which form cysts and then tubulate in response to HGF, are a much more in vivo-like system for the identification of novel tubulogenes. With the use of a canine microarray containing over 20,000 genes, 2,417 genes were identified as potential tubulogenes that were differentially regulated, exclusively in 3D-grown MDCK cells. Among these, 840 were dependent on MAPK signaling. Importantly, this work shows that many putative tubulogenes, previously identified via microarray analysis of 2D cultures, including by us, do not change in 3D culture and vice versa. The use of a 3D-culture system allowed for the identification of novel MAPK-dependent and -independent genes that regulate early renal tubulogenesis in vitro, e.g., matrix metalloproteinase 1 (MMP1). Knockdown of MMP1 led to defects in cystogenesis and tubulogenesis in 3D-grown MDCK cells, most likely due to problems establishing normal polarity. We suggest that data obtained from 2D cultures, even those using MDCK cells treated with HGF, should not be automatically extrapolated to factors important for cystogenesis and tubulogenesis. Instead, 3D culture, which more closely replicates the biological environment and is therefore a more accurate model for identifying tubulogenes, is preferred. Results from the present analysis will be used to build a more accurate model of the signaling pathways that control cystogenesis and tubulogenesis.</P>