Vol. 2 No. 2 June 1997

Volume 2 (1997) pp 109-115
Title THE EFFECT OF LOW POWER LASER RADIATION ON THE CHINESE HAMSTER FIBROBLAST CELL MEMBRANE POTENTIAL
Authors K. Rekawiecka, D. Palecz, H. Schüsler** and M. Bryszewska*
Abstract The membrane potential of Chinese hamster fibroblasts was determined to be (-29,9 +/- 6.5) mV. Fibroblast membranes irradiated with red laser light of 670 nm were partially depolarized. This effect was observed for energy doses of 5 J and 10 J.The energy dose of 15 J did not further decrease the membrane potential. In contrast to the red light, the irradiation with green laser light (543.5 nm) did not change fibroblast membrane potential..
Address and Contact Information Institute of Biophysics, Medical Biophysics Unit, University of Lodz, Banacha 12/16,90-237 Lodz, Poland
* Corresponding author: fax: (4842) 35 44 73, e-mail: marbrys@biol.uni.lodz.pl
**Institute of Medical Physics, University of Erlangen-Nuremberg, Germany
[Rozmiar: 1332 bajtów]

Volume 2 (1997) pp 117-124
Title THE KEDEM-KATCHALSKY EQUATIONS AS APPLIED FOR DESCRIBING SUBSTANCE TRANSPORT ACROSS BIOLOGICAL MEMBRANES
Authors A. Kargol*, M. Kargol** and S. Przestalski***
Abstract The classical version of the Kedem-Katchalsky equations is suitable for describing substance transport in membrane systems with well-stirred bathing solutions. However, when dealing with biological reality we are faced with a more complicated situation. For instance, in the living cell one can distinguish the central bulk area where the cytoplasm is well stirred due to its natural streaming and a certain relatively thin layer adjacent to the plasma membrane where there is no stirring. In such situation, the passive transport of substance can be well described using the Kedem-Katchalsky equations in their more general form. The equations can, however, be applied provided the membrane boundary unstirred layers of cytoplasm are treated as diffusion layers. This has been shown in detail in the present work.
Address and Contact Information * Department of Physics, Eastern Mediterranean University, Famagusta, N. Cyprus, Mersin 10, Turkey
** Institute of Physisc, Pedagogical University, 25-509 Kielce, Lesna 16, Poland
***Department of Physics and Biophysics, Agricultural University, 50-375 Wroclaw, Norwida 25, Poland
[Rozmiar: 1332 bajtów]

Volume 2 (1997) pp 125-136
Title EFFECT OF STIRRING ON TRANSPERITONEAL TRANSPORT IN VITRO
Authors K. Czyzewska
Abstract The importance of stirring on the peritoneal absorption and excretion of urea (U), uric acid (UA) inulin (I) and albumin in vitro was analysed. Changes of mixing rate modified the dynamics of the peritoneal transport. These modification were transient. The increase of stirring intensity from 5 ml/min to 11 ml/min caused increase of the mean bidirectional transfer values of UA by about 40% and A by 70%, but not U and I. The increase of mixing from 11 ml/min to 22 ml/min elevated only transperitoneal transfer of A by about 110% in comparison with the control. The obtained results confirm the suggestion that increasing of fluid mixing on the mesothelial and interstitial side of the membrane influences the transperitoneal transfer rate by reduction of unstirred fluid layer. This diffusion resistance in vitro, in contrast to in vivo, is more important for the transport of macromolecular than micromolecular, neutral solutes
Address and Contact Information Department of Pathophysiology, Karol Marcinkowski University of Medical Sciences, Swiecickiego 6, 60-781 Poznan, Poland
[Rozmiar: 1332 bajtów]

Volume 2 (1997) pp 137-150
Title PML SHUTTLES BETWEEN NUCLEAR BODIES AND THE CYTOPLASM
Authors Nico Stuurman* , Arno Floore, Esther Middelkoop**, Roel van Driel and Luitzen de Jong***
Abstract Nuclear bodies are electron dense, spherical structures with a diameter between 0.2 and 1.0 micrometer. The function of these nuclear domains is unclear. One class of nuclear bodies contains the tumor suppressor protein PML. Besides in the nucleus, a small number of PML- containing structures of about the same size as nuclear bodies is also present in the cytoplasm. We have investigated whether PML is transported from the nucleus to the cytoplasm and/or vice versa. To this end we injected the PML-specific mAb 5E10 into the cytoplasm of living cells. Subsequently, we monitored translocation of the antibody across the nuclear envelope by indirect immunofluorescent microscopy. It is well known that antibodies in the cytoplasm of living cells do not enter the nucleus, unless as a complex with a karyophilic protein. We observed accumulation into PML-containing nuclear bodies of 5E10 microinjected into the cytoplasm. Control rabbit IgG and a mAb specific for lamin B2 were not translocated to the nucleus. All nuclear PML bodies were labeled simultaneously by 5E10 with gradually increased intensity in time. Labeling of PML-containing nuclear bodies by 5E10 microinjected into the cytoplasm was not affected by inhibition of protein synthesis. These results suggest that the 5E10 antigen PML shuttles between the nucleus and cytoplasm, indicating that nuclear bodies are dynamic structures.
Address and Contact Information E.C. Slater Instituut, BioCentrum Amsterdam, University of Amsterdam, Plantage Muidergracht 12, 1018TV Amsterdam, The Netherlands
* Present address: Marice Mueller Institut, University of Basel, CH-4056 Basel, Switzerland
** Present address: Department of Dermatology, Academic Medical Centre, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
*** Corresponding author: tel: +31 20 525 5136, fax: +31 20 525 5124, e- mail: a311luit@chem.uva.nl
[Rozmiar: 1332 bajtów]

Volume 2 (1997) pp 151-159
Title CELLULAR UPTAKE AND CYTOTOXICITY OF FREE AND LIPOSOME ENCAPSULATED COLCHICINE
Authors S.B. Kulkarni and G.V. Betageri
Abstract Besides its use in gouty arthritis, colchicine has been found to be useful for anticancer treatment. However, the severe toxicity and low therapeutic index of colchicine limit its therapeutic use. It was hypothesized that toxicity of colchicine can be reduced if it is encapsulated in liposomes. The objective of this study was to determine and compare in vitro cellular uptake and cytotoxicity of colchicine with that of liposome encapsulated colchicine. Colchicine was encapsulated in negatively charged unilamellar liposomes (LUVs). Two cell lines, human macrophages (U-937) and murine myeloma (B-type, P3X63.Ag8.653) cells were used for these investigations. Cells were incubated with colchicine or liposomal colchicine and cellular uptake was determined by means of radioactive labeled colchicine. Cytotoxicity was determined by MTT (3-[4,5-dimethylthiazol- 2-yl]-2,5-diphenyl tetrazolium bromide) assay. Human macrophages as well as murine myeloma cells showed greater uptake of liposomal colchicine than plain colchicine. However, cytotoxicity of liposomal colchicine to human macrophages was less compared to that of plain colchicine. On the other hand, in the case of murine myeloma cells, cellular uptake as well as cytotoxicity was greater with liposomal colchicine than that with plain colchicine. These results indicate that liposomal encapsulation of colchicine could avoid or reduce its toxicity and improve therapeutic efficacy.
Address and Contact Information Department of Pharmacal Sciences, School of Pharmacy Auburn University, Auburn, AL 36849, USA
[Rozmiar: 1332 bajtów]

Volume 2 (1997) pp 161-173
Title HYDROGEN FLUORIDE EFFECTS ON PLASMA MEMBRANES STEROL AND PHOSPHOLIPID COMPOSITION IN NEEDLES OF EASTERN WHITE PINE (Pinus strobus L.) SEEDLINGS PRETREATED WITH DIFFERENT PHOTOPERIOD CONDITIONS
Authors K. J. Rakowski
Abstract Eastern white pine (Pinus strobus L.) seedlings were pre-treated with 12 h photoperiod to induce dormancy or with 18 h photoperiod to accelerate growth. Dormant and non-dormant plants were fumigated with 0.5 ppb (0.4 microg m-3) or 2.0 ppb (1.6 microg m-3) hydrogen fluoride (HF) for 2-28 days. Plasma membranes were isolated from needles of HF treated and control seedlings to determine their particular sterol and phospholipid composition. For all analyses, only those plants which did not show needle necrosis were selected. Analyses of plasma membrane sterol indicated significant increase in sitosterol content observed after 2 days in non-dormant and after 28 days in dormant plants. Analyses of plasma membrane phospholipid fatty acids indicate most significant increase in oleic acid (18:1) level in non-dormant seedlings after 2 and 8 days of HF treatment. Dormant plants expressed decreased level of all analysed fatty acids (18:1, 18:2, 18:3). Results obtained indicate the possibility of direct hydrogen fluoride effect on fatty acid composition resulting in non-specific plasma membrane phospholipid degradation during plant dormancy. On the other hand, increased sitosterol and oleic acid level suggest more specific fluoride effects on particular sterol and phospholipid synthesis in non-dormant seedlings.
Address and Contact Information Department of Genetics and Forest Trees Physiology, Forest Research Institute, Bitwy Warszawskiej 1920R-3, 00-973 Warsaw, Poland.
[Rozmiar: 1332 bajtów]

Volume 2 (1997) pp 175-195
Title CARBOXYL TERMINAL FRAGMENT OF b-AMYLOID PRECURSOR PROTEIN: ELECTROPHYSIOLOGICAL EFFECTS AND CELLULAR TOXICITY
Authors S.P. Fraser*, A.A. Bryan*, J.K.J. Diss*,**, J-H. Kim*,***, S-H. Kim***, Y-H. Suh*** and M.B.A. Djamgoz*
Abstract Alzheimer's disease (AD) is characterized by deposition of b-amyloid (Ab) in areas of the brain. Ab is a metabolic fragment of the b-amyloid precursor protein (bAPP). Genetic evidence has linked bAPP to AD, and there is increasing evidence that fragments from bAPP are neurotoxic. Ab, the main research focus, has been shown to induce depolarizing ion channel activity. Involvement of other cleaved products from bAPP are less clear. We have investigated the 105 amino acid C-terminal peptide (CT105) (containing the full sequence Ab), an alternative fragment linked with cellular toxicity. CT105 induced non-selective ionic currents in Xenopus oocytes (a model cell used in cell signalling studies) and was toxic to oocytes and mammalian cortical neurones. These results suggest possible involvement of CT105 in inducing the neural toxicity characteristic of AD.
Address and Contact Information * Neurobiology Group, Department of Biology, Imperial College of Science, Technology and Medicine,London, SW7 2BB, UK.
** International Marine Centre, 09072 Oristano, Italy.
*** Department of Pharmacology, Seoul National University, College of Medicine, Chongno Gu, Seoul 110-799, Korea.
[Rozmiar: 1332 bajtów]

Volume 2 (1997) pp 197-211
Title IS LEPTIN WHAT WE ARE LOOKING FOR ?
Authors J.S.C. Clark and D. Kielar*
Abstract Leptin and its receptors are newly dicovered factors involved in regulation of energy homeostasis and body weight. Leptin is specifically produced and secreted by adipocytes, but its receptor isoforms have a wide tissue distribution and in many experiments it has been demonstrated that leptin also plays a regulatory role in hematopoiesis, development, reproduction and perhaps glucose metabolism. In this short review we summarise the recent discoveries surrounding leptin, its receptors and their genes, and discuss the possible web of interactions
Address and Contact Information Department of Clinical Biochemistry, Pomeranian Medical Academy, Powstancow Wielkopolskich 72, 70-111 Szczecin, Poland.
* Corresponding author: tel: 04891 826074 or 826075, fax: 04891 821251
[Rozmiar: 1332 bajtów]

Volume 2 (1997) pp 213-222
Title INHIBITION OF SOYBEAN LIPOXYGENASES BY RESORCINOLIC LIPIDS FROM CEREAL BRAN
Authors L.Deszcz and A. Kozubek
Abstract Incubation of soybean lipoxygenase isoenzymes (L-1,L-2, and L-3) with total resorcinolic lipids isolated from wheat bran or their purified homologs (5-n-pentadecylresorcinol and 5-n-tricosylresorcinol) led to apparent inhibition of all three isoenzyme activities. The IC50 values determined for studied compounds showed that the inhibitory activity was related to the length of the resorcinolic lipid aliphatic chain and was more effective for homolog with longer chain attached to 1,3-dihydroxybenzene ring in metha position. Similar dependence on the length of the alkylresorcinol side chain was observed also for Ki values. The 5-n-tricosylresorcinol (23:0 AR) was found to be the most efficient inhibitor of soybean lipoxygenases with IC50 values in the range of several (M regardless of the substrate used (linoleic acid or arachidonic acid). All alkylresorcinols studied caused increase of apparent KM values and decrease of VMAX values of the enzymes thus suggested the mixed type of lipoxygenase inhibition.
Address and Contact Information Institute of Biochemistry, Wroclaw University, Przybyszewskiego 63/77, 51-148 Wroclaw, Poland
deszcz@microb.uni.wroc.pl
[Rozmiar: 1332 bajtów]

ABSTRACTS of contributions to W. Mejbaum-Katzenellenbogen's Seminars on Molecular Biology 4. Nuclear Organization and Intracellular Transport (ARF and 14-3-3 Protein) June 23-25, 1997, Wroclaw/Szklarska Poreba