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PubMed2006

Quantum mechanical modeling of self-assembly and photoinduced electron transfer in PNA-based artificial living organisms.

In order to support the creation of both artificial living organisms in the USA LANL "Protocell Assembly" project and programmable nano-biorobots in the EU "Programmable Artificial Cell Evolution" project, we used quantum mechanical (QM), density functional theory (DFT), the semiempirical PM3 method, and molecular mechanics (MM) software to investigate various complex photosynthetic systems based on peptide nucleic acid (PNA) in a water environment. Quantum mechanical DFT PBEPBE simulations, including electron correlations, confirm that water molecules that surround all the photosynthetic complex of the LANL protoorganism are main constructing factors and stabilize this system consisting of: PNA fragment attached by covalent bond sensitizer 1,4-bis(N,N-dimethylamino)naphthalene molecule, lipid precursor molecule and fragment of lipid molecules mono layer. The absorption spectrum shift to the red wavelengths in the complex artificial protocell photosynthetic center might be used as the measure of the complexity of this system. The electron pi-pi* transitions in the first and third excited states are from HOMO and HOMO-1 located on the conjugated water molecules and sensitizer 1,4-bis(N,N-dimethylamino)naphthalene molecule to the LUMO of the lipid precursor molecule as calculated using the time dependent (TD) PBEPBE/6-31G model. Electron charge tunneling in the first and third excited states should induce metabolic photodissociation of the lipid precursor molecule because of localization of the transferred electron cloud on the head (waste) of the lipid precursor molecule. TD electron correlation PBEPBE/6-31G calculations show that in the different energies of excitation, the charge transfer tunneling is from sensitizer to lipid precursor and cytosine molecules. One should note that in a water solvent, the electron charge transfer pi-pi* transition in the fifth and sixth excited state is from the HOMO and HOMO-1 located on the sensitizer 1,4-bis(N,N-dimethylamino)naphthalene molecule to the LUMO+2 located on the cytosine-PNA fragment molecule. Investigation results indicate that strong back electron tunneling from the sensitizer 1,4-bis(N,N-dimethylamino)naphthalene molecule to the cytosine molecule in the LANL artificial photosynthetic system exists.

Biomimetics↗
PubMed1998

My life with Dr. Willem Kolff.

Since 1957, I have been well aware of Dr. Kolff's contribution in the field of artificial organs. Therefore, when I came to the United States, the first thing I knew I wanted to do was to meet Dr. Kolff. I finally met him on April 16, 1962 in Cleveland. At that time, I never dreamed that one day I would be working for him even though I had already been involved in the field of artificial organs. During the 3 years that I worked for Dr. Kolff, between April 1, 1964 and March 31, 1967, I obtained the basic training and foundation for succeeding him in the Department of Artificial Organs, Cleveland Clinic Foundation. During those first 10 years after succeeding Dr. Kolff, I devoted myself to reestablishing the department. He was always supportive of me in establishing my objective. Beginning in 1977, together with Dr. Kolff, I devoted my life to establishing and maintaining the International Society for Artificial Organs (ISAO) as the leading organization in the world for artificial organ technologies. Dr. Kolff was also supportive of this effort. Without his support, I, as well as others in the world who are involved in artificial organ technologies, believe that the ISAO would not be what it is today. We are very grateful to him for his contributions in this field.

Animals↗
PubMed2006

The fixation of living skin equivalents.

Histologic evaluations and immunohistochemical characterizations are important in studies of artificial organs such as skin equivalents. However, tissue compact organization is not easy to obtain when the artificial organ is constructed in vitro. Thus, appropriate fixation methods must be selected according to the compactness of the artificial organ and tissue engineering methodologies. The effects of several fixatives-Carnoy, Bouin's solution, formalin, paraformaldehyde, and paraformaldehyde-glutaraldehyde-were examined to select the best fixation method for preserving the structural and molecular markers of skin equivalents. Formalin-based fixatives ware found to be relatively free of the histologic problems (e.g., tissue shrinkage, poor structural preservation, weak stainability, and nonspecific immunolocalization) presented by the soft tissue fixatives (i.e., Carnoy or Bouin's solution). Unfortunately, the standard concentration of formalin induced detachment of epidermis from dermis, but this was prevented by reducing the concentration of the fixative. These findings suggest that fixation procedures should be selected for particular tissue and specific goals; in particular, they show that the paraformaldehyde-glutaraldehyde combination performed best in terms of preserving the histologic features of skin equivalents.

Eosine Yellowish-(YS)↗
PubMed1987

[Therapy of acute renal failure--filtration--dialysis, when?].

Artificial organ support ("artificial kidney") is part of the therapeutic regimen as a whole in patients with acute renal failure. The absolute indications for an artificial kidney (hyperkalemia, hyperhydration, uremic encephalopathy), should be prevented by modern intensive care in the majority of cases. Hemofiltration has the advantage of better cardiovascular tolerance, but is less effective than hemodialysis in respect to elimination of toxins with low molecular weight. The continuous arterio--venous hemofiltration (CAVH) bears the advantage of continuous elimination and minimal cardiovascular side effects.

Acute Kidney Injury↗
PubMed2003

Application of Taylor vortices in hemocompatibility investigations.

BACKGROUND: Artificial organs, implants and extracorporeal circulation affect the physiological flow characteristics of blood as a liquid organ. These artificial systems consist of a wide variety of biomaterials with different geometries and, therefore, with their own flow properties. Secondary flow also occurs in extra--as well as in intracorporeal circulation. METHODS: In order to investigate the influence of vortical flow conditions a modified Taylor-Couette system was introduced. It consisted of two coaxial cylinders whose surfaces were the target of investigation. The annular gap was filled with donor blood shear and secondary flows were produced by rotating the inner cylinder. Platelet activation and protein adsorption were investigated as markers for thrombogenicity. RESULTS: At shear rates high enough to establish stable Taylor vortices (G > or = 550 s(-1)) significant differences between vortical Taylor flow and steady laminar flow were detected. At shear rates of G > or = 550 s(-1) laminar flow caused a significantly higher platelet drop and PF4 release when compared to Taylor vortex flow. Also protein adsorption per square unit was significantly higher for laminar flow. CONCLUSIONS: Based on the present data we conclude that vortical flow patterns lead to an accumulation of platelets and plasma proteins in the vortex center and therefore to a decreased probability of contact between platelets and material surfaces. It can be concluded that a preactivation of the platelets circulating in extracorporeal circuits can be manifested downstream in other geometrical configurations and flow conditions.

Adsorption↗
PubMed2006

[Educational system for medical sciences at the University of Tsukuba--with special reference to medical technology].

Three-year colleges for nursing, medical technology, and so on, have all been reorganized into four-year educational institutions in national universities. Since the reform, universities are not responsible for educating medical scientists except nurses. The new College of Nursing and Medical Technology in the University of Tsukuba has been developed along these lines. Here introduce some of its attempts and provide an opportunity to a better system. The Department has the following three characteristics: 1. Medical scientists are educated in the new Department, and the Department is closely cooperating with the School of Medicine. 2. There are courses for medical researchers concerning Molecular Pathology, Pathological Engineering and Environmental Pathology. 3. The qualification to apply to a national test for medical technologists is given to the students. Unfortunately, the system is not fully understood by the faculty or the students and does not work well because the Medical Technology Department and the Nursing Department are grouped together as a single institution. Moreover, this flaw in the system prevents the Medical Technology Department from actively promoting highly advanced medical sciences, such as organ transplantation, artificial organs, gene therapy, reproductive medicines, and so forth (Fig. 1). Few specialists exist who can bridge achievements in basic or advanced sciences and clinical application. Serious social problems about food safety, care systems, post-genome medicine, the youth, and so on, have to be dealt with, too. We are thus planning to separate the Department as the College of Medical Science (Fig. 2) and link it to the educational system in the master's and doctoral programs (Fig. 3). This model will successfully educate a new type of medical specialists.

Curriculum↗
PubMed1989

[Experiences of a regional coordinating center in preparing for organ donations].

Potential organ donors can be expected in every hospital. In the GDR, the annual number of donors nearly corresponds to the number of hospitals, e.g. 1985:500. Even if they work as donor hospitals only once every 1 to 2 years, medical and organizational problems are unavoidable. Taking this aspect into consideration, a regional coordinating centre for the District of Magdeburg with 1.3 million inhabitants and 24 hospitals was established in 1981 at the Clinic for Anaesthesiology and Intensive Therapy of the Magdeburg Medical Academy. This centre advises the "donor-hospitals" and admits potential donors if they are transportable. In 8 years, the centre was consulted in 148 cases. Fifty-six of the resulting organ explantations were performed at the centre. The main advantages of such a centralized service are: permanent presence of specialists who are experienced in organ donor procedures, close local and organizational links to special groups for diagnosing brain death, performing organ explantation, artificial organ perfusion and organ transportation, the possibility to admit patients for "donor conditioning".

Germany, East↗