Volume 5 (2000) pp 3-18 |
Title |
MOLECULAR BIOLOGY AND CLINICAL IMPLICATIONS OF THE
ADENOMATOUS POLYPOSIS COLI (APC) GENE |
Authors |
Roman Miturski1, Dominique Burnouf2, Mark Nothisen2,
Michal Bogusiewicz1 and Jerzy A. Jakowicki1 |
Abstract |
This review describes the structure of the adenomatous polyposis coli
(APC) gene with expressed proteins and their possible tissue interactions. The
functions of APC in animals and humans are discussed. The mutational
spectrum with clinical impact on colon pathology and gynaecological pathology
similarities are presented, along with a discussion of a highly sensitive
molecular biology test. |
Address and Contact Information |
1Department of Gynaecological Surgery, Lublin School of Medicine,
Jaczewskiego 8, 20-090 Lublin, Poland, 2Laboratory of Cancerogenesis
and Mutagenesis Molecular and Structural, UPR 9003, IRCAD,
Place de l'Hôpital 1, 67000 Strasbourg, France 1To whom correspondence should be addressed |
|
Volume 5 (2000) pp 19-34 |
Title |
SURFACE MODIFIED LIPOSOMES BY COATING WITH CHARGED
HYDROPHILIC MOLECULES+ |
Authors |
M. Luisa Sagristă, Margarita Mora
and M. Africa De Madariaga* |
Abstract |
The design of liposomes with a hydrophilic/steric barrier at their
bilayer surface allows the modification of their pharmacokinetics and reduces the
uptake by the RES. Liposomes can be coated by hydrophilic molecules such as
polysaccharides, which disguise the vesicle surface by creating a threedimensional
matrix near them and prevent the binding of plasma proteins and
their recognition by some cellular receptors. All these considerations, and
previous results obtained in our laboratory showing the formation of stable GAGliposome
complexes, have lead us to think about the use of the negatively charged
glycosaminoglycans (GAGs), alternately to other molecules such as the
monosialoganglioside GM1, more expensive, or polyethylene glycol (PEG-PE)
that can disturb the structural organization of the bilayer.
The present paper describes the effect of the incorporation of GAGs to
phospholipid vesicles, in relation to their electrical and permeability properties.
The results obtained show that there is an effective coating of the bilayer surface
when glycosaminoglycans are added to liposome suspensions. The shielding of the
negative surface charge by the neutral hyaluronic acid, in the absence of calcium,
and the increase in the negative charge when the negative polyelectrolytes
chondroitin sulfate, heparin or dextran sulfate are added to calcium-containing
liposome suspensions account for the formation of stable liposome-GAG
complexes. Moreover, the reduced permeability of the GAG-coated liposomes
points out on their ability to hold encapsulated drugs and, so, their potential
usefulness as drug-sustained release carriers. The hydrophilic coating will give to
these liposomal carriers long-circulating properties. |
Address and Contact Information |
Department of Biochemistry and Molecular Biology, Faculty of Chemistry,
University of Barcelona, Martă i Franques 1, 08028-Barcelona, Spain |
|
Volume 5 (2000) pp 35-50 |
Title |
WHAT DOES LIPID HYDRATION TELL US? A MINIREVIEW+ |
Authors |
Gordon L. Jendrasiak and Ralph L. Smith |
Abstract |
The hydration of a variety of phospholipids has been studied,
gravimetrically. The water adsorption isotherms obtained have been analyzed
by the use of BET methodology. The major findings are as follows:
Phospholipids containing choline, as part of their head group and having a
glycerol backbone are "strong" water adsorbers; the nature and fluidity of the
hydrocarbon chains do not control the "strong" vs "weak" nature of the water
binding but do modulate the amount of adsorbed water.
The number of methyl groups present on the N + moiety of the head groups
determines both the nature of the water binding as well as the amount of water
adsorbed.
The electrical charge on the phospholipid head group does not, in itself,
determine the nature of the water binding; it does, however affect the amount of
water bound.
All of the phospholipids studied exhibit a very rapid rise in electrical
conductivity as water is adsorbed; this rise reaches a limiting saturation value at
or close to that for the completion of the first monolayer of water adsorbed.
These findings are discussed in terms of the molecular structure of the
phospholipids. |
Address and Contact Information |
East Carolina University, School of Medicine, Department of Radiation
Oncology, Greenville, NC 27858, USA |
|
Volume 5 (2000) pp 51-66 |
Title |
EFFECTS OF DIOLEOYLPHOSPHATIDYLETHANOLAMINE ON
THE ACTIVITY AND STRUCTURE OF O-ALKYL PHOSPHATIDYLCHOLINE-
DNA TRANSFECTION COMPLEXES+ |
Authors |
Vera A. Rakhmanova1, Thomas J. Mcintosh2
and Robert C. Macdonald1 |
Abstract |
O-alkyl derivatives of dioleoylphosphatidylcholine (DOPC) have
been previously described as effective DNA transfection reagents. This
communication reports the effects of the neutral helper lipid
dioleoylphosphatidylethanolamine (DOPE) on the efficiency of transfection of
BHK cells mediated by the O-ethyl-, O-hexyl-, and O-octadecyl- DOPC
derivatives, compounds that by themselves are known to exhibit lyotropic phase
preferences of lamellar, lamellar or cubic (depending on conditions) and inverse
hexagonal, respectively. The effect of DOPE on transfection efficiency was
found to be inhibition of the ethyl compound, stimulation or inhibition
(depending on amount of DOPE) of the hexyl compound and stimulation in the
case of the octadecyl compound, i.e., DOPE had a beneficial effect on the lipids
that formed non-lamellar phases. X-ray diffraction was used to determine the
lyotropic phase of the lipid-DOPE mixtures and of the lipid-DNA complex.
DNA-lipid complexes tended to be lamellar unless the lipids had a very strong
tendency toward the hexagonal phase, in which case the DNA complex was also
hexagonal. Thus, a mixture of equal amounts of DOPE and hexyl-DOPC
formed a lamellar complex with DNA, although the lipids on their own
assumed the hexagonal phase. Octadecyl-DOPC formed a hexagonal phase
with DOPE and the 1:1 DOPE mixture formed a hexagonal phase DNA
complex; however, if smaller amounts of DOPE were included, the complex
had a lamellar structure, in contrast to the hexagonal phase of the lipids by
themselves. For these cationic phospholipids, there was not necessarily a
benefit to transfection of generating a hexagonal phase lipid-DNA complex. |
Address and Contact Information |
1Department of Biochemistry, Molecular Biology and Cell Biology,
Northwestern University, Evanston, IL 60208, 2The Department of Cell
Biology, Duke University, Durham, NC 27710 |
|
Volume 5 (2000) pp 67-74 |
Title |
MODIFICATION OF MECHANICAL PROPERTIES OF MODEL
MEMBRANES BY SOME BIFUNCTIONAL SURFACTANTS |
Authors |
Halina Kleszczynska, Janusz Sarapuk
and Bozenna Różycka-Roszak |
Abstract |
Interaction of two series of new surfactants with an incorporated antioxidant
functional group with erythrocytes and planar lipid membranes was studied.
Surfactants were synthesized in order to be potentially used as common
bio-cides or as agents protecting biological and/or model membranes against
lipid peroxidation. Both applications need the use of such bifunctional
surfactants in significantly different concentrations. The aim of this work was to
find the concentration range in which surfactants studied could be used as
biocides. Two different models were chosen in order to do it; pig erythrocyte
and asolectin planar membranes. The studied parameters of these models were
hemolysis of red blood cells and stability of BLM in the presence of the
compounds studied, i. e., the parameters describing mechanical properties of
model membranes used. Additionally, the role of the counterions in the
interaction of bifunctional surfactants with model membranes was studied. It
was found that both homologous series of the surfactants influence model
membranes to different degree depending on the length of their hydrophobic
part and the kind of counterion. In the latter case it seems that the differences in
the hydrated radii of bromide and chloride ions, and hence the differences in
their ability to modify electrostatic interaction between the lipid polar heads and
compounds studied, are responsible for the effects o bserved. |
Address and Contact Information |
Agricultural University, Department of Physics and Biophysics, Norwida 25, |
|
Volume 5 (2000) pp 75-90 |
Title |
THE MALIGNANT TRANSFORMATION OF SYRIAN HAMSTER
EMBRYO (SHE) CELLS IN PRIMARY CULTURE BY MALACHITE
GREEN: THE TRANSFORMATION IS ASSOCIATED WITH
ENHANCED VIMENTIN PHOSPHORYLATION, PCNA EXPRESSION
AND BrdU INCORPORATION |
Authors |
Daisy M. Mahudawala, Alka A. Redkar and K.V.K. Rao * |
Abstract |
Malachite green (MG) consisting of green crystals with a metallic
lustre, is very soluble in water and is highly cytotoxic to mammalian cells and
also acts as a liver tumor promoter. In view of its industrial importance and
possible exposure to human beings, MG poses a potential environmental health
hazard. The malignant transformation of Syrian hamster embryo (SHE) cells by
MG has been reported earlier. In this study, an attempt has been made to study
the levels of vimentin, vimentin phosphorylation and the expression of PCNA
and BrdU incorporation in MG transformed cells compared to control cells.
Immunohistochemical and immunoprecipitation studies showed enhanced levels
of vimentin in transformed cells compared to normal cells. Metabolic labelling
studies showed an overall increase in phosphorylation of total cellular proteins
as well as hyperphosphorylation of vimentin in transformed cells. Transformed
cells also showed an increased doubling time, PCNA expression and BrdU
incorporation. This study indicates a close relationship between vimentin levels,
hyperphosphorylation of vimentin and increased cell proliferation associated
with the malignant transformation of SHE cells. |
Address and Contact Information |
Cellular Carcinogenesis Laboratory, Cancer Research Institute,
Parel, Mumbai - 400012, India *Corresponding author, tel: 91-22-4123803, ext.255; fax: 91-22-4146089; e-mail:
cri3@soochak.ncst.ernet.in |
|
Volume 5 (2000) pp 91-106 |
Title |
SERINE PROTEINASE INHIBITOR FAMILY IN SQUASH SEEDS:
MUTATIONAL VARIABILITY MECHANISM AND CORRELATION |
Authors |
Jacek Leluk |
Abstract |
Proteinase inhibitors from squash seeds were analyzed for mutational
variability. The non-homologous positions were subjected to an analysis of the
interrelation between occurring residues and the mechanism of variability, using
the algorithm of genetic semihomology [1]. The study also concerned
mutational correlation at particular positions and their contact with each other. It
was observed that:
- the number of residues occupying particular positions varies from 1 to 8
- the mechanism of variability is based on single point mutation
- the variable positions are seldom in contact with each other
- the mutations in distant positions (not in contact with each other) are
correlated with each other
- the correlated mutations refer to those positions which are far from the
reactive site of the inhibitor
- the mutational variability in primary structure within this family is not
consistent with the Markovian model of amino acid replacement.
|
Address and Contact Information |
|
|
Volume 5 (2000) pp 107-118 |
Title |
THE INFLUENCE OF BOLAAMPHIPHILIC STEROID DIMER
ON THE FORMATION AND STRUCTURE OF BILAYER LIPID
MEMBRANES+ |
Authors |
Sławomir Kalinowski1 , Zenon Łotowski2 and Jacek W. Morzycki2 |
Abstract |
The process of self-assembly and the electromechanical properties of
bilayer lipid membranes (BLM) were investigated. The membranes were made
of phosphatidylcholine with the addition of bolaamphiphilic steroid dimer. The
membranes were formed using the Mueller-Rudin method. Membrane
formation in the presence of the dimer was much faster and they were more
stable than those formed in the absence of the dimer. The membranes formed by
this method usually contain residues of a solvent used in the formation process
which increases membrane thickness. Thus, the membranes formed from pure
phosphatidylcholine had an average thickness of 5.9 nm. The addition of steroid
dimer to the forming solution caused the thickness to decrease to 3.9 nm. An
external voltage applied to the bilayer lipid membranes caused
electrocompression. The presence of bolaamphiphilic steroid dimer in the
membranes decreased the electrocompressibility by approximately 20 times.
The dimer molecules „spanned” both monolayers of the membranes and caused
the membrane thickness to decrease during their formation. The presence of the
dimer in the membrane limited the mobility of solvent inside the membrane.
The membranes formed with the dimer have such properties as thickness,
stability, resistance, breakdown voltage, electrocompressibility, and time of
formation more adequate for their application as a biomembrane model and
support for sensors based on biomembrane molecules. |
Address and Contact Information |
1Warmia and Masuria University in Olsztyn, Department of Chemistry,
10-957 Olsztyn, Poland, 2 |
|
Volume 5 (2000) pp 119-132 |
Title |
STRATEGIES FOR TARGETING AND RELEASE OF ACTIVE ANTICANCER
AND ANTI-MICROBIAL DRUGS FROM LIPOPHILIC
PRODRUGS AND FROM MICROPARTICLES+ |
authors |
Milton B. Yatvin1, Michael J. Meredith2, M. Sanusi Jangi1
and Mohan A. Shenoy1 |
Abstract |
Many anti-cancer and antiviral drugs currently used are either unable
or inefficient in their ability to pass through the blood brain-barrier and to enter
and maintain therapeutic drug levels in brain. The low bioavailability of these
drugs is a limiting factor in their use.
In order to overcome these limitations, we ester-linked various anti-cancer and
antiviral drugs to ceramide and phosphatidylcholine and created prodrugs
possessing therapeutic attributes lacking in the parent compounds. This resulted
in greater cellular uptake and prolonged retention of these prodrugs in vitro.
Likewise, prodrug concentration was greater and retention time longer than the
parent drug in the brain, testes and thymus of mice.
Another major goal in drug development is discovering compounds that have
efficacy against a specific microorganism or virus without significant side
effects. For example, many potentially good drugs cannot be used because they
are either toxic to uninfected cells or they cannot be restricted to a certain part
of the body. If a drug could remain inert unless and until it is inside an infected
cell, many of the common problems associated with drug treatments would be
solved.
In an attempt to address this problem we are developing a method by which a
drug will be released only in cells that are infected with a particular
microorganism or virus. The methodology makes use of the fact that
microparticles are ingested by macrophages. Cell-specific treatment can be
achieved by combining a drug with a microparticle using microorganismspecific
enzyme substrates. Thus, release of active drug will occur only in the
presence of enzymes specific to the target virus or microorganism. In the
uninfected macrophage drug remains bound to the microparticle and is inactive.
In the infected cell active drug is released by enzymatic hydrolysis. Potential applications for this technology include all diseases in which pathogens are
resident in macrophages and other phagocytic cells. |
Address and Contact Information |
1Division of Radiation & Thermal Biology, School of Medicine, 2Department
of Oral Molecular Biology, School of Dentistry Oregon Health Sciences
University, Portland, OR 97201 |
|