bluuebunny/crossref_metadata_2025 huggingface dataset:
Maternal and cord blood serum levels of zinc, copper, and iron in healthy pregnant Jordanian women
Authors: Awadallah S.M. , Abu‐Elteen K.H. , Elkarmi A.Z. , Qaraein S.H. , Salem N.M. , Mubarak M.S.
Published: January 2004

Altered plasma levels of zinc, copper, and iron during pregnancy are known to have profound effects on pregnant women and their neonates. The status of these elements is not known in pregnant women in Jordan. During the three trimesters of pregnancy, blood specimens were collected from 186 healthy pregnant women aged 17–45 years and from cord blood of 92 of their neonates. The mean neonatal birth weight was 3.34 ± 0.44 kg. Maternal and cord blood serum levels of zinc, copper, and iron were determined by atomic absorption spectrophotometry, and hemoglobin concentration was determined by hematology cell counter. The results indicate significantly lower serum zinc levels and higher copper and iron levels in cord blood than in maternal blood. During the three trimesters of pregnancy, the serum levels of zinc and copper significantly decreased and increased, respectively, whereas the levels of serum iron were unchanged. Significant positive correlation was observed only between zinc levels of cord blood and birth weight. During third trimester, the mean serum levels of zinc and iron were significantly lower in anemic pregnant women (group I: Hb less than 11.0 g/dL, n = 36) than that in nonanemic pregnant women (group II: Hb > or = 11.0 g/dL, n = 56). There was no noticeable difference between group I and group II regarding cord blood parameters on one hand and neonatal birth weight on the other hand. Similar significant positive correlation was observed between serum zinc levels of cord blood and birth weight in both groups. These results indicate that Jordanian women during pregnancy follow a well‐balanced and adequate diet regime. J. Trace Elem. Exp. Med. 17:1–8, 2004. © 2004 Wiley‐Liss, Inc.
Possible role of trace elements in the hypoglycemic effect of plants extract in diabetic rats
Authors: Al‐Awadi F.M. , Anim J.T. , Srikumar T.S. , Al‐Rustom Mona
Published: January 2004

The present study is designed to investigate the possible role of zinc, copper, manganese, and selenium on the hypoglycemic action of a plants mixture and alfalfa using a diabetic rat model. Diabetes was induced in male Wister rats using streptozotocin and confirmed by estimation of glucose levels in blood and urine and further by histologic examination of the pancreas. The animals were treated with the plants mixture and alfalfa extracts orally by gastric intubation for 7 days. Untreated normal and diabetic rats were included as controls. After evaluating glucose tolerance, animals were sacrificed and organs harvested for trace element analysis and histopathological study. The concentration of zinc, copper, manganese, and selenium in plasma, liver, and pancreas of diabetic rats was significantly lower than those of nondiabetic controls. Treatment of diabetic rats with plants mixture and alfalfa significantly decreased the blood glucose concentration but increased the levels of zinc, copper, manganese, and selenium in plasma, liver, and pancreas. Similar changes occurred in the nondiabetic normal control animals treated with the same products. Histological and immunohistochemical examination also confirmed the presence of more β‐cells in the islets of treated diabetic animals compared with untreated diabetic controls. There was no histological evidence of damage to the liver of either diabetic or normal control animals treated with the plants extract. The present study indicated that treatment of diabetes with naturally available plants mixture appears to be effective and the hypoglycemic effect could be through a multimechanism action including that exerted by the trace element content in the different tissues including the pancreas. J. Trace Elem. Exp. Med. 17:31–44, 2004. © 2004 Wiley‐Liss, Inc.
Inhibitory effect of tannic acid on iron–dextran‐augmented and 7,12‐dimethyl benz(a)anthracene‐initiated skin carcinogenesis
Authors: Babaei Hossein , Nayebi Ali Reza Mohajjel , Rezazadeh Hassan , Abdulla Mohamed
Published: January 2004

Tannic acid (TA) is naturally occurring polyphenol present in fruits and vegetables. In this study we report that TA inhibits the carcinogenic effect of 7,12‐dimethylbenz(a)anthracene (DMBA) in normal and iron‐overloaded mice skin. Albino Swiss mice were given iron–dextran and pretreated with a single topical application of tannic acid; after 1 h, tumors were initiated by multiple topically application of DMBA. Appearance, number, and percent tumor incidence were recorded. When compared with the control group, the pretreated groups showed a significantly higher inhibition of tumor incidence. The induction of [3H]thymidine incorporation in cutaneous DNA and lipid peroxidation was inhibited in TA‐pertreated animals as compared with the normal control group. Based on this study, we propose that TA significantly inhibits the augmentation potential of iron–dextran. A depletion in lipid peroxidation levels in TA‐pretreated groups indicates that excessive generated oxidants in the mice skin tissues may be quenched by TA and because of the chelation of redox active iron and its faster elimination from the body. In conclusion, our data suggest that TA may be an effective chemopreventive agent and may offer protection against iron mediated skin cancer. J. Trace Elem. Exp. Med. 17:21–29, 2004. © 2004 Wiley‐Liss, Inc.
Lead intoxication: Histological and oxidative damage in rat cerebrum and cerebellum
Authors: Sidhu Pardeep , Nehru Bimla
Published: January 2004

The present experiment was designed to study the neurotoxic consequences of lead exposure on antioxidant enzymes like glutathione, glutathione peroxidase, super oxide dismustase, and catalase along with structural changes both in cerebrum as well as cerebellum. Lead was administrated orally in the doses of 50 mg/kg for a period of 8 weeks and study was performed at the end of exposure. Decrease in the concentration of all the antioxidant enzymes was observed, and after lead treatment, transverse sections of cerebrum showed degeneration of neurons. Disruption of normal arrangement of cell layers was seen. Cells were bigger in size with large vascular spaces around them. Lead treatment for 8 weeks also was enough to disrupt the normal arrangement of cellular layer of cerebellum. Large spaces in between purkinje cell layer and granular layer were seen. J. Trace Elem. Exp. Med. 17:45–53, 2004. © 2004 Wiley‐Liss, Inc.
Can long‐term exposure to chromium improve insulin sensitivity in chromium mine workers?
Authors: Tuzcu A. , Bahcecı M. , Dursun M. , Parmaksız Y. , Ertem M. , Dalgıc A. , Turgut C. , Kale E.
Published: January 2004

The purpose of this work was to evaluate insulin sensitivity in chromium mine workers exposed to chromium chronically. Body mass index, waist circumference, fat mass and percent, lipid levels, serum glucose, insulin, leptin and chromium levels, HOMA (%S), and HOMA (%B) values were measured in 93 male workers and 94 age‐ and body mass index‐matched healthy controls. Fat mass and fat percent of workers were higher than control subjects (P < 0.01 and P < 0.0001, respectively). Mean insulin level of the workers was lower than control subjects (6.2 ± 4.9 μU/mL and 9.38 ± 5, respectively, P < 0.0001). Mean serum leptin levels was also lower than the control group (8.47 ± 6.5 ng/mL and 19.0 ± 10.8, respectively, P < 0.0001). Serum chromium was higher than the control subjects (407.7 ± 224.2 nmol/L and 4.45 ± 3.9, respectively, P < 0.00001). Mean HOMA (%S) index of workers was higher than control subjects (114.4 ± 55.6 and 55.7 ± 40.6, P < 0.001). Serum high‐density lipoprotein cholesterol levels of the workers were significantly higher than the control group (P < 0.02). In conclusion, long‐term exposure to chromium may improve insulin sensitivity and β‐cell function. This improvement appears to be a result of low body fat mass and fat percent in body composition. In addition, chromium usage may have useful effects in the insulin sensitivity and therefore in development of type 2 diabetes mellitus. J. Trace Elem. Exp. Med. 17:55–63, 2004. © 2004 Wiley‐Liss, Inc.
Compound load of copper and iron in the livers of pretreatment patients with Wilson's disease
Authors: Harashima Ai , Hattori Ai , Hayashi Hisao , Wakusawa Shinya , Kusakabe Atsuhiko , Fujita Yoshikazu , Tanaka Minoru , Yano Motoyoshi , Yoshioka Kentaro
Published: January 2004

Ceruloplasmin is a major ferroxidase in sera, and people with hypoceruloplasminemia might have iron load complications. We used histochemical and X‐ray microanalysis techniques on pretreatment liver specimens from five patients with Wilson's disease. Serum levels of ceruloplasmin and ferritin were determined before chelation therapy. All the patients showed hypoceruloplasminemia ranging from 15 to 160 mg/L. Histo‐chemical copper was positively stained in four of the five patients. Copper deposits were clearly observed in the hepatocyte lysosomes of one patient. High serum ferritin levels ranging from 188 to 400 ng/mL were found. Histochemical iron was positive in the livers of two patients. Iron‐specific X‐rays were positive in the hepatocyte lysosomes of all the patients. These findings suggest that compound load of copper and iron is a fundamental finding in the liver of Wilson's disease with hypoceruloplasminemia. Copper cytotoxicity is a primary target for chelation therapy, and iron load, if hepatotoxic, should be treated by phlebotomy. J. Trace Elem. Exp. 17:65–73, 2004. © 2004 Wiley‐Liss, Inc.
Effect of melatonin treatment on liver and thymus zinc levels in young and middle‐aged rats
Authors: Öztürk Güler , Akbulut K. Gonca , Afrasyap Lale , Sevinç Deniz
Published: January 2004

Melatonin (MEL) is the main neurohormone of the pineal gland. Zinc (Zn) is an essential trace element that is required as a catalytic component for more than 200 enzymes. Both MEL and Zn are considered beneficial for anti‐immunosenescence. Recent findings have shown that MEL can modulate Zn turnover. The aim of this study was to investigate the effect of MEL treatment on the tissue Zn levels in young (4 months) and middle‐aged (14 months) rats. Male wistar rats received during 3 weeks subcutaneous injection of MEL (10 mg/kg). After 3 weeks, rats were decapitated and tissue samples were collected. Zn levels were measured by spectrophotometric assay. In conclusion, MEL decreased liver Zn levels both in young and middle‐aged rats. In addition, Zn levels in young control group were significantly higher than middle‐aged control group. However, MEL treatment increased thymus Zn levels in middle‐aged group compared with the control. These findings indicate that tissue Zn levels are significantly affected by MEL treatment. J. Trace Elem. Exp. Med. 17:75–80, 2004. © 2004 Wiley‐Liss, Inc.
LiNbO3 Pockels cell for Q-switch of Er:YAG laser
Authors: Jelínková H , Šulc J , Koranda P , Němec M , Čech M , Jelínek M , Škoda V
Published: January 2004

Specially designed LiNbO3 electrooptic shutter was
used for Q-switching of Er:YAG laser system. Brewster angles was
employed at the Pockels cell LiNbO3 crystal faces to avoid the
insertion of a polarizer into the resonator. By help of the
theoretical analysis based on Jones calculus, the dependency of
Pockels cell radiation transmission on applied voltage was found.
Theoretically and experimentally was proved, that for 25 mm long
LiNbO3 crystal the voltage of 1.5 kV is sufficient to avoid
the laser oscillation. With this Pockels cell a stable running
Q-switched Er:YAG laser system was realized. The generated giant
pulse length and energy was 70 ns and 30 mJ, respectively.
Nd:YAG laser interaction with mine wrapping materials
Authors: Rothacher T , Weber R , Lüthy W , Weber H P
Published: January 2004

According to UN publications landmines are a daily
threat in approximately 70 countries of the world. There exist
different ways to destroy detected antipersonnel mines.
Neutralisation of mines with laser is a possibility that offers
several advantages like working from safe distance and possibly
mine destruction by deflagration and without explosion. Previous
work has shown the importance of an absorbing mine wrapping
material to achieve the desired burning process. In this paper,
interaction of Nd:YAG laser radiation with different realistic
synthetic mine wrapping materials is investigated. Penetration
duration of laser radiation at λ = 1.064 μm through
samples with different thickness is measured. Penetration through
all tested materials is achieved at an incident power of 28.8 W.
With an investigated material thickness up to 3 mm, penetration
duration is in the range of seconds. Also penetration through a
real mine case consisting of bakelite is achieved.
Corollary to Noether's theorem about the conservation of angular momentum and spin in theories that are dealing with strong laser fields
Authors: Ristić V M , Radulović M M
Published: January 2004

We have shown that Noether's theorem [16] has a corollary which proves non-conservation of angular momentum and spin in ``mixed'' theories (the ones that combine classical and quantum approach). As laser field is treated classically and atoms with which it interacts must be treated as quantum objects (see, for instance [1], where the ADK-theory is described, which we take as a represent of ``mixed'' theories), it is shown that in such theories the law of conservation of the 4-angular momentum tensor is broken. As there are many other theories that can be defined as "mixed" [see, for instance, 18], we think the result being interesting enough, though that evident shortcoming does not affect the results of ADK-theory, because it never operates with spin, and the most probable ejected electrons have orbital quantum numberl= 0 [8, 17]. However it should be stressed that the corollary we have proveddoes notimply that the law of conservation of angular momentum and spin is not valid in general, but only that one should be cautious when treating angular momentum and spin in "mixed" theories.
In vivo determination of doxorubicin and its metabolites within the
skin using laser scanning microscopy
Authors: Jacobi U , Waibler E , Bartoll J , Schulze P , Sterry W , Lademann J
Published: January 2004

Much research in medicine is focused on the development
of antitumoral therapies. The encapsulation of the active single
chemotherapy agent doxorubicin in highly stable
Stealth® liposomes can cause
dominant and dose-limiting mucocutaneous reactions, such as the
hand-foot syndrome. The aim of the present study was to determine
the kinetic and localization of doxorubicin or its metabolites
within the skin in vivo. Therefore, a laser scanning microscope
was used to excite and detect the fluorescence of these compounds.
The approach was tested on porcine skin after topical application
of the agent prior to measurement. Subsequently, the laser
scanning microscope was used to study skin areas mainly affected
by the hand-foot syndrome on a patient who had undergone a therapy
with the encapsulated doxorubicin
(Caelyx®). Fluorescence was
detected on the skin surface of the axilla, on the forehead inside
furrows and the sebaceous glands (1 h after commencement of the
treatment) and within the skin of the sole and the palm (2 h after
beginning the injection). These signals were determined for up to
3.5 h. The results obtained indicate that both the sweat glands
and sebaceous glands function as pathways for the release of
doxorubicin or its metabolites. The described method opens the
possibility for further studies to develop and test prevention
strategies against the hand-foot syndrome.
Structure determination of aligned samples of membrane proteins by NMR spectroscopy
Authors: Nevzorov Alexander A. , Mesleh Michael F. , Opella Stanley J.
Published: January 2004

The paper briefly reviews the process of determining the structures of membrane proteins by NMR spectroscopy of aligned samples, describes the integration of recent developments in the interpretation of spectra of aligned proteins and illustrates the application of these methods to the trans‐membrane helical domain of a protein. The emerging methods of interpreting the spectral parameters from aligned samples of isotopically labeled proteins provide opportunities for simultaneously assigning the spectra and determining the structures of the proteins, and also for comparing the results from solid‐state NMR experiments on completely aligned samples with those of solution NMR experiments on weakly aligned samples. Copyright © 2004 John Wiley & Sons, Ltd.
Structural studies of apoptosis and ion transport regulatory proteins in membranes
Authors: Franzin Carla M. , Choi Jungyuen , Zhai Dayong , Reed John C. , Marassi Francesca M.
Published: January 2004

Solid‐state NMR spectroscopy is being used to determine the structures of membrane proteins involved in the regulation of apoptosis and ion transport. The Bcl‐2 family includes pro‐ and anti‐apoptotic proteins that play a major regulatory role in mitochondrion‐dependent apoptosis or programmed cell death. The NMR data obtained for 15N‐labeled anti‐apoptotic Bcl‐xL in lipid bilayers are consistent with membrane association through insertion of the two central hydrophobic α‐helices that are also required for channel formation and cytoprotective activity. The FXYD family proteins regulate ion flux across membranes, through interaction with the Na+, K+‐ATPase, in tissues that perform fluid and solute transport or that are electrically excitable. We have expressed and purified three FXYD family members, Mat8 (mammary tumor protein), CHIF (channel‐inducing factor) and PLM (phospholemman), for structure determination by NMR in lipids. The solid‐state NMR spectra of Bcl‐2 and FXYD proteins, in uniaxially oriented lipid bilayers, give the first view of their membrane‐associated architectures. Copyright © 2004 John Wiley & Sons, Ltd.
Structural diversity of amyloid fibril formed in human calcitonin as revealed by site‐directed 13C solid‐state NMR spectroscopy
Authors: Naito Akira , Kamihira Miya , Inoue Ryozo , Saitô Hazime
Published: January 2004

Fibril formation in human calcitonin (hCT) from aqueous solution at pH 4.1 was examined and compared with those at pH 3.3 and 7.5 corresponding to three different net charges by means of site‐directed 13C solid‐state NMR spectroscopy. Notably, the observed 13C chemical shifts and lineshapes of the 13C CP/MAS spectra differed substantially among fibrils prepared at different pHs. It was found that antiparallel β‐sheet structures were formed at pH 7.5 and 4.1 in the central core regions. In the C‐terminal region, random coils were formed at both pH 7.5 and 4.1, although the random coil region at pH 4.1 was larger than that at pH 7.5. Fibrillation kinetics analyzed by a two‐step autocatalytic reaction mechanism showed that the rate constants k1 and k2 for nucleation and maturation reactions of the fibril formation, respectively, were separately determined and the values correlated well with the net positive charges of Lys18 and His20 rather than the existence of a negative charge of Asp15. Further, an attempt was made to assess interatomic distances between amide nitrogen and carbonyl carbon of neighboring chains of 13C, 15N‐labeled hCT and a model pentapeptide by 13C REDOR measurements by taking into account its dipolar interaction analyzed by the 3 spin system proposed previously. A unique chain packing of the antiparallel β‐sheets was proposed as a dominant fibril structure, although the possibility of a contribution of chain packing consisting of sliding one or two residues perpendicular to the fibril direction cannot be ruled out. In addition, it appears that the phenyl rings of Phe16 are aligned on the same side of the β‐sheet and make the β‐sheet stable by forming π–π interactions between the β‐strands. Copyright © 2004 John Wiley & Sons, Ltd.
Investigation of the dynamics of an elastin‐mimetic polypeptide using solid‐state NMR
Authors: Yao Xiao L. , Conticello Vincent P. , Hong Mei
Published: January 2004

Elastin is the main structural protein that provides elasticity to various tissues and organs in vertebrates. Molecular motions are believed to play a significant role in its elasticity. We have used solid‐state NMR spectroscopy to characterize the dynamics of an elastin‐mimetic protein as a function of hydration to better understand the origin of elastin elasticity. Poly(Lys‐25), [(VPGVG)4(VPGKG)]39, has a repeat sequence common to natural elastin. 13C cross‐polarization and direct polarization spectra at various hydration levels indicate that water enhances the protein motion in a non‐uniform manner. Below 20% hydration, the backbone motion increases only slightly whereas above 30% hydration, both the backbone and the side‐chains undergo large‐amplitude motions. The motional amplitudes are extracted from 13C–1H and 1H–1H dipolar couplings using 2D isotropic–anisotropic correlation experiments. The root mean square fluctuation angles are found to be 11–18° in the dry protein and 16–21° in the 20% hydrated protein. Dramatically, the amplitudes increase to near isotropic at 30% hydration. Field‐dependent 1H rotating‐frame spin–lattice relaxation times (T1ρ) indicate that significant motions occur on the microsecond time‐scale (1.2–2.3 µs). The large‐amplitude and low‐frequency motion of poly(Lys‐25) at relatively mild hydration indicates that the conformational entropy of the protein in the relaxed state contributes significantly to the elasticity. Copyright © 2004 John Wiley & Sons, Ltd.
Temperature dependence and resonance assignment of 13C NMR spectra of selectively and uniformly labeled fusion peptides associated with membranes
Authors: Bodner Michele L. , Gabrys Charles M. , Parkanzky Paul D. , Yang Jun , Duskin Craig A. , Weliky David P.
Published: January 2004

HIV‐1 and influenza viral fusion peptides are biologically relevant model fusion systems and, in this study, their membrane‐associated structures were probed by solid‐state NMR 13C chemical shift measurements. The influenza peptide IFP‐L2CF3N contained a 13C carbonyl label at Leu‐2 and a 15N label at Phe‐3 while the HIV‐1 peptide HFP‐UF8L9G10 was uniformly 13C and 15N labeled at Phe‐8, Leu‐9 and Gly‐10. The membrane composition of the IFP‐L2CF3N sample was POPC–POPG (4:1) and the membrane composition of the HFP‐UF8L9G10 sample was a mixture of lipids and cholesterol which approximately reflects the lipid headgroup and cholesterol composition of host cells of the HIV‐1 virus. In one‐dimensional magic angle spinning spectra, labeled backbone 13C were selectively observed using a REDOR filter of the 13C–15N dipolar coupling. Backbone chemical shifts were very similar at −50 and 20°C, which suggests that low temperature does not appreciably change the peptide structure. Relative to −50°C, the 20°C spectra had narrower signals with lower integrated intensity, which is consistent with greater motion at the higher temperature. The Leu‐2 chemical shift in the IFP‐L2CF3N sample correlates with a helical structure at this residue and is consistent with detection of helical structure by other biophysical techniques. Two‐dimensional 13C–13C correlation spectra were obtained for the HFP‐UF8L9G10 sample and were used to assign the chemical shifts of all of the 13C labels in the peptide. Secondary shift analysis was consistent with a β‐strand structure over these three residues. The high signal‐to‐noise ratio of the 2D spectra suggests that membrane‐associated fusion peptides with longer sequences of labeled amino acids can also be assigned with 2D and 3D methods. Copyright © 2004 John Wiley & Sons, Ltd.
15N T2′ relaxation times of bacteriorhodopsin transmembrane amide nitrogens
Authors: Soubias Olivier , Réat Valérie , Saurel Olivier , Milon Alain
Published: January 2004

15N T2′ relaxation times of bacteriorhodopsin (BR) amide nitrogens were determined in the temperature range from 40 to −60°C using a Hahn echo pulse sequence and proton decoupling during the echo and detection times. Using oriented membrane samples, with their bilayer normal parallel to the external magnetic field, the 15N amide nitrogens belonging to the transmembrane helices could be selected for the analysis. The experiments were performed on purple membrane fragments (in which BR is organized in a 2D crystalline network) and on BR reconstituted into dimyristoylphosphatidylcholine at a 1:150 molar ratio (in which BR is in a freely diffusing monomeric state at 40°C and in an aggregated state at 4°C and below). The results are discussed in terms of helix dynamics, mosaic spread and resolution of the 15N spectra for the various samples and experimental conditions. Copyright © 2004 John Wiley & Sons, Ltd.
Conformational response of the phosphatidylcholine headgroup to bilayer surface charge: torsion angle constraints from dipolar and quadrupolar couplings in bicelles
Authors: Semchyschyn Darlene J. , Macdonald Peter M.
Published: January 2004

The effects of bilayer surface charge on the conformation of the phosphocholine group of phosphatidylcholine were investigated using a torsion angle analysis of quadrupolar and dipolar splittings in, respectively, 2H and 13C NMR spectra of 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphocholine (POPC) labelled in the phosphocholine group with either deuterons (POPC‐α‐d2, POPC‐β‐d2 and POPC‐γ‐d9) or carbon‐13 (POPC‐α‐13C and POPC‐αβ‐13C2) and incorporated into magnetically aligned bicelles containing various amounts of either the cationic amphiphile 1,2‐dimyristoyl‐3‐trimethylammoniumpropane (DMTAP) or the anionic amphiphile 1,2‐dimyristoyl‐sn‐glycero‐3‐phosphoglycerol (DMPG). Three sets of quadrupolar splittings, one from each of the three deuteron labelling positions, and three sets of dipolar splittings (13Cα–31P, 13Cα–13Cβ, 13Cβ–14N), were measured at each surface charge, along with the 31P residual chemical shift anisotropy. The torsion angle analysis assumed fast anisotropic rotation of POPC about its long molecular axis, thus projecting all NMR interactions onto that director axis of motion. Dipolar, quadrupolar and chemical shift anisotropies were calculated as a function of the phosphocholine internal torsion angles by first transforming into a common reference frame affixed to the phosphocholine group prior to motional averaging about the director axis. A comparison of experiment and calculation provided the two order parameters specifying the director orientation relative to the molecule, plus the torsion angles α3, α4 and α5. Surface charge was found to have little effect on the torsion angle α5 (rotations about Cα–Cβ), but to have large and inverse effects on torsion angles α3 [rotations about P–O(11)] and α4 [rotations about O(11)–Cα], yielding a net upwards tilt of the P–N vector in the presence of cationic surface charge, and a downwards tilt in the presence of anionic surface charge, relative to neutrality. Copyright © 2004 John Wiley & Sons, Ltd.
Properties of polyunsaturated phosphatidylcholine membranes in the presence and absence of cholesterol
Authors: Epand Richard M. , Epand Raquel F. , Bain Alex D. , Sayer Brian G. , Hughes Donald W.
Published: January 2004

Mixtures of cholesterol with phosphatidylcholine species containing the polyunsaturated acyl chains arachidonoyl or docosahexaenoyl were studied by 13C magic angle spinning (MAS) NMR using both cross‐polarization and direct polarization, by 31P NMR and by differential scanning calorimetry. Several unique features of these systems were observed. The separation of cholesterol in crystalline form occurred at much lower molar fractions than with other forms of phosphatidylcholine. The crystals that were formed were sensitive to the history of the sample. At cholesterol molar fractions below 0.5, they dissolved into the membrane by sequential heating and cooling scans. With higher molar fractions of cholesterol, larger amounts of anhydrous crystals were formed after the first heating. This was accompanied by the formation of non‐lamellar phases. The cholesterol crystals that were formed generally were not observed by direct polarization 13C MAS NMR, even with delay times of 100 s. This suggests that the cholesterol crystals are in a more rigid state in mixtures with these lipids. This is in contrast with the terminal methyl group of the acyl chains that is too mobile to allow cross‐polarization using 1 ms contact times. Copyright © 2004 John Wiley & Sons, Ltd.
Lateral diffusion studied by pulsed field gradient NMR on oriented lipid membranes
Authors: Orädd Greger , Lindblom Göran
Published: January 2004

This mini‐review focuses on the utilization of pulsed magnetic field gradients to measure diffusional motion in systems of macroscopically oriented lipid bilayers. The NMR diffusion technique is proposed to have appreciable potential for future biophysical investigations in the field of membrane biology. Topics such as transport of molecules both across and in the plane of the membrane can be successfully studied, and the formation of lipid domains and their intrinsic dynamics can also be scrutinized. First, a short introduction to the NMR technique is given together with a brief discussion on methods of obtaining a good bilayer orientation. Then, a number of recent results on biophysical/biological membrane systems of great interest is presented, in which some unique conclusions on so‐called ‘raft membranes’ are reached. It is shown for systems with large two‐phase areas of liquid disordered and liquid ordered phases that lipid lateral diffusion is faster in the former phase and has a smaller apparent activation energy. Further, on the time‐scale of the experiments (50–250 ms), exchange between the two phases is fast in the phospholipid–cholesterol–water ternary system, whereas it is slow in the sphingomyelin–dioleoylphosphatidylcholine–cholesterol–water quaternary system. Copyright © 2004 John Wiley & Sons, Ltd.
‘Boomerang’‐like insertion of a fusogenic peptide in a lipid membrane revealed by solid‐state 19F NMR
Authors: Afonin Sergii , Dürr Ulrich H. N. , Glaser Ralf W. , Ulrich Anne S.
Published: January 2004

Solid state 19F NMR revealed the conformation and alignment of the fusogenic peptide sequence B18 from the sea urchin fertilization protein bindin embedded in flat phospholipid bilayers. Single 19F labels were introduced into nine distinct positions along the wild‐type sequence by substituting each hydrophobic amino acid, one by one, with L‐4‐fluorophenylglycine. Their anisotropic chemical shifts were measured in uniaxially oriented membrane samples and used as orientational constraints to model the peptide structure in the membrane‐bound state. Previous 1H NMR studies of B18 in 30% TFE and in detergent micelles had shown that the peptide structure consists of two α‐helical segments that are connected by a flexible hinge. This helix–break–helix motif was confirmed here by the solid‐state 19F NMR data, while no other secondary structure (β‐sheet, 310‐helix) was compatible with the set of orientational constraints. For both α‐helical segments we found that the helical conformation extends all the way to the respective N‐ and C‐termini of the peptide. Analysis of the corresponding tilt and azimuthal rotation angles showed that the N‐terminal helix of B18 is immersed obliquely into the bilayer (at a tilt angle τ ≈ 54°), whereas the C‐terminus is peripherally aligned (τ ≈ 91°). The azimuthal orientation of the two segments is consistent with the amphiphilic distribution of side‐chains. The observed ‘boomerang’‐like mode of insertion into the membrane may thus explain how peptide binding leads to lipid dehydration and acyl chain perturbation as a prerequisite for bilayer fusion to occur. Copyright © 2004 John Wiley & Sons, Ltd.
Amyloidosis of Alzheimer's Aβ peptides: solid‐state nuclear magnetic resonance, electron paramagnetic resonance, transmission electron microscopy, scanning transmission electron microscopy and atomic force microscopy studies
Authors: Antzutkin Oleg N.
Published: January 2004

Aggregation cascade for Alzheimer's amyloid‐β peptides, its relevance to neurotoxicity in the course of Alzheimer's disease and experimental methods useful for these studies are discussed. Details of the solid‐phase peptide synthesis and sample preparation procedures for Alzheimer's β‐amyloid fibrils are given. Recent progress in obtaining structural constraints on Aβ‐fibrils from solid‐state NMR and scanning transmission electron microscopy (STEM) data is discussed. Polymorphism of amyloid fibrils and oligomers of the ‘Arctic’ mutant of Aβ(1–40) was studied by 1H,13C solid‐state NMR, transmission electron microscopy (TEM) and atomic force microscopy (AFM), and a real‐time aggregation of different polymorphs of the peptide was observed with the aid of in situ AFM. Recent results on binding of Cu(II) ions and Al–citrate and Al–ATP complexes to amyloid fibrils, as studied by electron paramagnetic resonance (EPR) and solid‐state 27Al NMR techniques, are also presented. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis and structure–activity relationship of new analogues of antistasin
Authors: Danalev Dantcho L. , Vezenkov Lyubomir T. , Grigorova Boryana
Published: January 2004

Intensive investigation connected with the development of new anticoagulant agents for the treatment of cardiovascular diseases was carried out. Direct and specific inhibition of thrombin and Factor Xa–like serine proteases in the coagulation cascade has been the focus of many efforts to design novel anticoagulants over the past decade. This work reports the synthesis and biological activity of new anticoagulant peptide analogues of natural isoforms 2 and 3 of antistasin. In addition they include different tripeptide sequences in their molecules, which are highly active inhibitors of different serine proteases such as plasmin, trypsin, thrombin and Factor Xa. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
Novel carbohydrate‐induced modification of peptides: crystal structure and NMR analysis of ester‐bridged bicyclic galactose‐enkephalin adduct containing imidazolidinone moiety
Authors: Kojić‐Prodić Biserka , Perić Berislav , Roščić Maja , Novak Predrag , Horvat Štefica
Published: January 2004

Comparative studies based on x‐ray crystallography and NMR spectroscopy were used for structural characterization of the novel minor, imidazolidinone moiety containing, product 2b of the Maillard reaction obtained in vitro by using the galactose‐modified endogenous opioid pentapeptide leucine‐enkephalin (Tyr‐Gly‐Gly‐Phe‐Leu) 1. The x‐ray analysis uniquely defined the molecular structure as cyclo‐{N‐{[2‐[‐4)‐D‐galacto‐pentitol‐1‐yl]‐4‐(4‐hydroxybenzyl)‐5‐oxoimidazolidin‐1‐yl‐(1 → O]acetyl}glycyl‐L‐phenylalanyl‐L‐leucyl‐} (3), having an 18‐membered ring with an ester bond between the secondary (C4′) hydroxyl group of a D‐galacto‐pentitolyl residue and the C‐terminal carboxy group of leucine‐enkephalin. The absolute configuration of the new chiral centre at the imidazolidinone moiety was established as C2(S), indicating a cis arrangement of C2 and C4 substituents at the 5‐membered heterocyclic ring. The NMR analysis of compound 2b carried out in CH3CN‐d3 and DMSO‐d6, indicated the existence of two isomers in solution, differing only in the position of the ester group in the molecule. NMR data for the minor isomer (13%–16%) are in agreement with structure 3. The migratory tendency of the peptidyl group from the primary (2b) to the secondary hydroxyl group (3) of a D‐galacto‐pentitolyl residue in methanol/water solution was confirmed by RP HPLC analysis. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
Heteroclitic recognition of combinatorial TX1TX2T peptide mixtures by mucin‐2 protein specific monoclonal antibody
Authors: Windberg Emôke , Uray Katalin , Illyés Eszter , Skribanek Zsolt , Price Michael R. , Sebestyén Ferenc , Hudecz Ferenc
Published: January 2004

The mucin‐2 (MUC2) glycoprotein secreted by the epithelial cells of human colon may be abnormally under‐glycosylated in the case of cancer. Monoclonal antibody (mAb) 994 raised against the immunogenic part of the protein core, recognizes malignant human colon tissues as well as pentapeptides with TX1TX2T motif present in MUC2. Using a combinatorial approach and ELISA experiments it was found that mAb 994 is able to recognize peptides of the sub‐library TQTX2T very strongly, and to some extent also peptides from TETX2T, TLTX2T and TVTX2T sub‐libraries. Binding studies with peptides corresponding to the TQTX2T and TETX2T sub‐libraries showed that mAb 994 recognized only six peptides (IC50 = 9–208 µmol dm−3) from the 19 compounds of the TQTX2T sub‐library and only three peptides (IC50 = 3500–16700 µmol dm−3) from the ‘second‐best’ TETX2T sub‐library. The most pronounced mAb binding occurred when Gln was in position X1 and it was much weaker in the case of Glu, Val or Leu. As for X2 amino acids, the presence of Pro, Ala can provide a strong, while Tyr, Trp, Phe and Ser a weaker, peptide–antibody interaction. Data from this study suggest that pentapeptide TQTPT, whose sequence is present in the native protein, is bound most strongly. However, almost identical binding properties were observed with peptide TQTAT, whose sequence is not present in the protein. Apart from this, some other ‘heteroclitic’ peptides were found with a different rank in the binding‐hierarchy. Based on these peptides artificial compounds can be prepared as potential candidates for vaccine development. Results of this study also provide a rationale for understanding the molecular background of the heteroclitic nature of the MUC2 protein core specific mAb 994. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
An unsaturated peptidomimetic assembly derived from a carbohydrate
Authors: Chung Ying‐Kit , Claridge Timothy D. W. , Fleet George W. J. , Johnson Stephen W. , Jones John H. , Lumbard Keith W. , Stachulski Andrew V.
Published: January 2004

A strategy has been established for the synthesis of peptidomimetics derived from unsaturated carbohydrates, and exemplified by the use of methyl 2,6‐anhydro‐7‐azido‐3,7‐deoxy‐4,5‐O‐isopropylidene‐D‐lyxo‐hept‐2‐enonate 9 as a dipeptide ‘monomer’ which can be elaborated from either end. Selective reduction of 9 gives a protected pseudodipeptide ester suitable for use as an amino component, and saponification gives an azido acid suitable for use as a carboxyl component. The ‘dimer’ product of coupling these two components with TBTU can be similarly elaborated at either end to give a ‘trimer’, and a further cycle of selective reduction and coupling gave a ‘tetramer’, 17, a pseudo‐octapeptide. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
New antitumour cyclic astin analogues: synthesis, conformation and bioactivity
Authors: Rossi Filomena , Zanotti Giancarlo , Saviano Michele , Iacovino Rosa , Palladino Pasquale , Saviano Gabriella , Amodeo Pietro , Tancredi Teodorico , Laccetti Paolo , Corbier Catherine , Benedetti Ettore
Published: January 2004

Astins, antitumour cyclic pentapeptides, were isolated from the Aster tataricus. Their chemical structures, consist of a 16‐membered ring system containing a unique β,γ‐dichlorinated proline [Pro(Cl)2], other non‐coded amino acid residues and a cis conformation in one of the peptide bonds. The astin backbone conformation, along with the cis peptide bond in which the β,γ‐dichlorinated proline residue is involved, was considered to play an important role in their antineoplastic activities on sarcoma 180A and P388 lymphocytic leukaemia in mice, but the scope and potential applications of this activity remain unclear. With the aim at improving our knowledge of the conformational properties influencing the bioactivity in this class of compounds, new astin‐related cyclopeptides were synthesized differing from the natural products by the presence of some non‐proteinogenic amino acid residues: Aib, Abu, ‐(S)β3‐hPhe and a peptide bond surrogate (‐SO2‐NH‐). The analogues prepared c(‐Pro‐Thr‐Aib‐β3‐Phe‐Abu‐), c[Pro‐Thr‐Aib‐(S)β3‐hPhe‐Abu], c[Pro‐Abu‐Ser‐(S)β3‐hPheΨ(CH2‐SO2‐NH)‐Abu] and c[Pro‐Thr‐Aib‐(S)β3‐hPheΨ(CH2‐SO2‐NH)‐Abu] were synthesized by classical methods in solution and tested for their antitumour effect. These molecules were studied by crystal‐state x‐ray diffraction analysis and/or solution NMR and MD techniques. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
Indices of lifetime polydrug use among adolescents
Authors: Sneed Carl D , Morisky Donald E , Rotheram‐Borus Mary Jane , Lee Sung‐Jae , Ebin Vicki J
Published: January 2004

The functional equivalency for three indices of lifetime polydrug use was examined in a sample of adolescents (N=794). The following indices were included in analyses: (a) a count of lifetime self‐report of substances used; (b) an index weighted by the severity of the substances used; and (c) a hierarchical index of substance use. Analyses for each index was conducted twice with abstinent youth (no report of substances over their lifetime) included and excluded from analyses. Relationships between the indices with gender, age, ethnicity, and country of origin were examined. The only difference between the indices found was for ethnicity in the full sample. African Americans had higher scores on the hierarchical substance use index than Latinos or Asian/Pacific Islanders. With the exception of the relationship between the hierarchical index and ethnicity, the relationships between the other demographic variables with indices were consistent. Implications for utilizing the count or weighted index versus a hierarchical index of lifetime polydrug use are discussed.
The reciprocal relationship between early adolescent attachment and internalizing and externalizing problem behaviour
Authors: Buist Kirsten L. , Deković Maja , Meeus Wim , van Aken Marcel A.G.
Published: January 2004

The aim of the present study is to examine the reciprocal relationship between parental attachment and adolescent internalizing and externalizing problem behaviour. In this longitudinal study, 288 adolescents (mean age 13.5 years) reported on their attachment relationships with their parents and on problem behaviour three times, with 1‐year‐intervals between measurement waves. Results show that attachment and both indicators of adolescent problem behaviour remain stable over time, although there were differences in stability between constructs. Reciprocal negative effects were found between attachment and internalizing problem behaviour, and between attachment and externalizing problem behaviour.
Precipitation and Northern Hemisphere regimes
Authors: Raible Christoph C. , Luksch Ute , Fraedrich Klaus
Published: January 2004

Rainfall anomalies in a longterm integration of general circulation model highlight the non‐stationarity of the ocean–atmosphere coupling in the North Atlantic which becomes manifest in two regimes. Anti‐correlations between the precipitation in the tropical and subtropical western Atlantic illustrate the changes of the Hadley cell with El Niño/Southern Oscillation (ENSO).The precipitation anomaly pattern in the north eastern Atlantic resembles variations of the North Atlantic storm track and the North Atlantic Oscillation (NAO). In the hemispheric regime, where 40% of the NAO variability can be explained by ENSO, both precipitation pattern are connected, whereas in the regional regime the ENSO‐link with the North Atlantic storm track and the subtropical 500 hPa geopotential height disappears. Copyright © 2004 Royal Meteorological Society. Published by Elsevier Ltd. All rights reserved.
Evolution of multicellularity in Metazoa: comparative analysis of the subcellular localization of proteins in Saccharomyces, Drosophila and Caenorhabditis
Authors: Hazkani‐Covo Einat , Levanon Erez Y. , Rotman Galit , Graur Dan , Novik Amit
Published: January 2004

A comparison of the subcellular assignments of proteins between the unicellular Saccharomyces cerevisiae and the multicellular Drosophila melanogaster and Caenorhabditis elegans was performed using a computational tool for the prediction of subcellular localization. Nine subcellular compartments were studied: (1) extracellular domain, (2) cell membrane, (3) cytoplasm, (4) endoplasmic reticulum, (5) Golgi apparatus, (6) lysosome, (7) peroxisome, (8) mitochondria, and (9) nucleus. The transition to multicellularity was found to be characterized by an increase in the total number of proteins encoded by the genome. Interestingly, this increase is distributed unevenly among the subcellular compartments. That is, a disproportionate increase in the number of proteins in the extracellular domain, the cell membrane, and the cytoplasm is observed in multicellular organisms, while no such increase is seen in other subcellular compartments.

A possible explanation involves signal transduction. In terms of protein numbers, signal transduction pathways may be roughly described as a pyramid with an expansive base in the extracellular domain (the numerous extracellular signal proteins), progressively narrowing at the cell membrane and cytoplasmic levels, and ending in a narrow tip consisting of only a handful of transcription modulators in the nucleus. Our observations suggest that extracellular signaling interactions among metazoan cells account for the uneven increase in the numbers of proteins among subcellular compartments during the transition to multicellularity.
Cerebral decreases in opioid receptor binding in patients with central neuropathic pain measured by [11C]diprenorphine binding and PET
Authors: Jones Anthony K.P. , Watabe Hiroshi , Cunningham Vin J. , Jones Terry
Published: January 2004

Central neuropathic pain (CNP) is pain resulting from damage to the central nervous system. Up till now, it has not been possible to identify a common lesion or pharmacological deficit in these patients. This preliminary study in a group of patients with CNP with predominantly post‐stroke pain, demonstrates that there is significantly less opioid receptor binding in a number of cortical and sub‐cortical structures that are mostly, but not exclusively, within the medial pain system in patients compared to age‐matched pain‐free controls. The reductions in opioid receptor binding within the medial system were observed mainly in the dorsolateral (Brodman area 10) and anterior cingulate (Brodman area 24 with some extension into area 23) and insula cortices and the thalamus. There were also reductions in the lateral pain system within the inferior parietal cortex (Brodman area 40). These changes in binding could not be accounted for by the cerebral lesions shown by CT or MRI, which were outside the areas of reduced binding and the human pain system. To our knowledge this is the first systematic demonstration of a reduction in opioid receptor‐binding capacity in neurones within the human nociceptive system in patients with CNP. This may be a key common factor resulting in undamped nociceptor activity within some of the structures that are predominantly within the medial nociceptive system. If confirmed, these findings may explain why certain patients with CNP require high doses of synthetic opiates to achieve optimum analgesia. The findings also raise the possibility of new pharmacological approaches to treatment.