bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimated moments at L5/S1 level and muscular activation of back extensors for six prone back extension exercises in healthy individuals
Authors: Plamondon A. , Serresse O. , Boyd K. , Ladouceur D. , Desjardins P.
Published: March 2003

The purpose of this study was to identify the prone back extension (PBE) exercises that offer the most resistance to the back extensor muscles. Twenty males with no previous history of low back injury performed two repetitions of eight exercises. These consisted of two maximal isometric voluntary activations (MVA) and six different PBE exercises. The participants, while lying prone on a bench, were asked to raise either their trunk or legs to the horizontal position and hold for one second (static phase) before returning to the original position. The exercises differed according to the particular segments that were raised into extension. To assess the PBE exercises, a biomechanical model was used to estimate the level of load resistance (%MVA) relative to the maximum voluntary activation strength (MVA). In addition, electromyography (EMG) was included to measure the level of muscle activity (%MVE) relative to the maximum voluntary activation EMG (MVE) value reached during the MVA. A significant relationship of 0.86 was found between the mass of the subject and the peak reaction moment during the MVA. Peak level of load resistance averaged around 50% MVA with the exception of exercise no. 5 where the subject had to raise in extension his trunk, legs and arms (65% MVA). The erector spinae (ES) activity level reached a peak value of 61% MVE for exercise no. 5. In the exercises where only the trunk was lifted, the peak level of ES was below 47% MVE and the average activity during the static phase reached approximately 26% MVE. For healthy individuals PBE exercises can be considered low intensity exercises (< 50% MVA; except exercise no. 5) and can be used to improve the endurance of the back muscles.
Effects of electrical stimulation‐induced leg training on skeletal muscle adaptability in spinal cord injury
Authors: Crameri R. M. , Weston A. , Climstein M. , Davis G. M. , Sutton J. R.
Published: March 2003

Neuromuscular electrical stimulation has grown in popularity as a therapeutic device for training and an ambulation aid to human paralyzed muscle. Despite its current clinical use, few studies have attempted to concurrently investigate the functional and intramuscular adaptations which occur after electrical stimulation training. Six individuals with a spinal cord injury performed 10 weeks of electrical stimulation leg cycle training (30 min d−1, 3 d week−1). The paralyzed vastus lateralis muscle showed significant alterations in skeletal muscle characteristics after the training, indicated by an improvement in total work output (52–112 kJ; P < 0.05), an increase in fiber cross‐sectional area (18 to 41 × 102 µm2; P < 0.05), a reduction in the percentage of type IIX fibers (75% to 12%; P < 0.05), a decrease in myosin heavy chain IIx (68% to 44%; P < 0.05), an increase in capillary density (2–3.5 capillaries around fiber; P < 0.05) and increases in activity levels of citrate synthase (7–16 mU mg−1 protein) and hexokinase (1.2–2.4 mU mg−1 protein). This study showed that 10 weeks of electrical stimulation training of human paralyzed muscle induces concurrent improvements in functional capacity and oxidative metabolism.
Biophysical measurements of human forearm skin in vivo: effects of site, gender, chirality and time
Authors: Chilcott Robert Peter , Farrar Rebecca
Published: March 2003

Background/aims: Measurements of transepidermal water loss (TEWL) and skin colour are biophysical techniques commonly used to measure the in vivo skin effects of cosmetics, topical medicaments and chemical irritants. The purpose of this study was to investigate the variability of TEWL and skin colour on human forearm skin as a function of regional variation, gender and preferred chirality over an 8 h period.

Methods: Biophysical measurements of TEWL and skin colour were made at five sites on both forearms of male (n=8) and female (n=9) human volunteers in vivo (38% relative humidity, 21°C).

Results: Rates of TEWL at the forearm midpoint were 10% lower than at the forearm extremities (P<0.01). Skin redness (a*) near the wrist was 5–10% higher than at other sites (P<0.05). Rates of TEWL were 5% higher in male volunteers (P<0.05). Red and blue (b*) colour measurements of male forearm skin differed by 18% and 20% in comparison with female, respectively. Rates of TEWL, skin brightness (L*) and b* decreased by 9% (P<0.05), 1.8% (P<0.05) and 4% (P<0.05), respectively, with time whereas a* and skin temperature increased by 4.5% (P<0.01) and 7.2% (P<0.01), respectively. There was a significant correlation between the change in all measured parameters with time.

Conclusions: Significant differences in TEWL and skin colour were identified that may have relevance in the design and interpretation of multivariate analyses of human forearm skin. Diurnal variation of TEWL, skin colour and temperature may have a single underlying mechanism.
Autofluorescence spectrum of skin: component bands and body site variations
Authors: Na Renhua , Stender Ida‐Marie , Ma Lixin , Wulf Hans Christian
Published: March 2003

Background/aims: The autofluorescence spectrum of skin consists of a number of overlapping single spectra emitted by fluorescent molecules. The overlapping makes it difficult to distinguish changes in the overall spectrum and the molecular basis for it. We applied curve fitting analysis to decompose the autofluorescence spectrum of normal human skin and studied the variation in different body sites.

Methods: Skin autofluorescence spectra were obtained in vivo from the normal skin of 17 subjects, using 5 excitation wavelengths: 340, 350, 360, 370 and 380 nm. The spectra were displayed in the wavelength range of 400 nm to 800 nm. Curve fitting was performed for each spectrum using the Levenberg–Marquardt algorithm.

Results: The skin autofluorescence spectra, provoked by all the excitation wavelengths, consisted of three component bands with center wavelengths at 450 nm, 520 nm and 625 nm. The 450 nm band contributed about 75% to the intensity of the overall spectrum, the 520 nm band contributed 25%, and the 625 nm band contributed about 2%. The three bands may correspond mainly to the fluorescence of nicotinamide adenine dinucleotide (NADH), flavin adenine dinucleotide (FAD), and porphyrins. Significant differences were found between the spectra of forehead and buttock skin. In forehead skin, the 625 nm band contributed more to the intensity of the overall spectrum, while the 450 nm and 520 nm bands had much lower peak heights, and the 450 nm and 625 nm bands were broader.

Conclusions: The autofluorescence of skin is an overlapped spectra of molecules such as NADH, FAD, and porphyrins. These molecules contribute differently to the overall spectrum in different body sites.
Instrumental evaluation of retinoid‐induced skin irritation
Authors: Stücker M. , Hoffmann M. , Altmeyer P.
Published: March 2003

Background/purpose Retinoids like tazarotene are approved for the treatment of chronic plaque psoriasis. In the beginning of topical retinoid therapy, 15–20% of the patients suffer from mild to moderate adverse reactions with burning and erythema. The aim of the study was to find predicative parameters of the individual irritative potential and to suggest options to reduce these initial irritations.

Methods Twenty in‐patients with different skin types (1 + 2: 11, 3 + 4: 9), with chronic plaque psoriasis were included in this open study. In each patient, 7 randomized plaques on the forearm were treated for 14 days on different ways: test area 1: morning (m) and evening (e) placebo, test area 2: placebo (m) and tazarotene 0.05% (e), test area 3: placebo (m) and tazarotene 0.1% (e), test area 4: calcipotriol (m) and calcípotriol (e), test area 5: mometasone furoate (m) and tazarotene 0.05% (e), test area 6: mometasone furoate (m) and tazarotene 0,1% (e), test area 7: placebo (m) and tazarotene in increasing concentrations (e), test area 8: healthy skin for control. Before and after therapy, skin barrier function, blood flow and plaque thickness in 20‐MHz sonography were assessed in different test areas intraindividually by non‐ invasive biophysical measurements.

Results After 14 days of therapy, tazarotene 0.05% and 0.1% produced a stronger increase of laser Doppler flow in patients with skin type 1 and 2 than in patients with skin type 3 and 4. When using the combination therapy of tazarotene and mometasone, the laser Doppler flow was significantly lower than in tazarotene as monotherapy. 20‐MHz‐ultrasound showed a significant decrease in the thickness of the echopoor band in all topical therapy regimens compared to placebo. Patients of skin type 1 and 2 reached a higher density of the dermis than patients of skin type 3 and 4, meaning a stronger decrease of inflammatory infiltration and acanthosis.

Conclusion Adapting retinoid therapy to the patient's skin type can reduce the initial irritative side‐effects. During the first days, patients with skin type 1 or 2 should add a medium potency corticosteroid. Stronger skin irritation caused by tazarotene therapy increases therapy effects.
Validation of segmentation techniques for digital dermoscopy
Authors: Joel Guillod , Philippe Schmid‐Saugeon , David Guggisberg , Jean Philippe Cerottini , Ralph Braun , Joakim Krischer , Jean‐Hilaire Saurat , Murat Kunt
Published: March 2003

Purpose: This study aims at evaluating two automatic contour detection techniques especially developed for dermoscopic images.

Methods: Twenty‐five images of lesions with a fuzzy boundary have been randomly selected. Five dermatologists experienced in dermoscopy have manually drawn the border of all the lesions and repeated the procedure after two and four weeks. The ability of a dermatologist to reproduce its own results was evaluated by measuring the non‐overlapping area enclosed by its three successive contours. The interobserver variability evaluated the contour accuracy when using automatic or manual drawings. The mean probability that a pixel has been misclassified was computed for every observer and automatic technique.

Results: Experts in dermoscopy are not able to reproduce measurements precisely and the two automatic techniques had a lower missclassification probability than those obtained by each dermatologist.

Conclusion: This study demonstrates that a single dermatologist should not be used as a reference, and subjective validation of lesion contour is inaccurate outside an experts's group. It is argued that image processing techniques for computer‐aided diagnosis must show the best compromise within such a group.
Sec7p Directs the Transitions Required for Yeast Golgi Biogenesis
Authors: Deitz Stephen B. , Rambourg Alain , Képès François , Franzusoff Alex
Published: March 2003

Endoplasmic reticulum (ER)‐to‐Golgi traffic in yeast proceeds by the maturation of membrane compartments from post‐ER vesicles to intermediate small vesicle tubular clusters (VTCs) to Golgi nodular membrane networks (Morin‐Ganet et al., Traffic 2000; 1: 56–68). The balance between ER and Golgi compartments is maintained by COPII‐ and COPI‐mediated anterograde and retrograde traffic, which are dependent on Sec7p and ARF function. The sec7‐4 temperature‐sensitive allele is a mutation in the highly conserved Sec7 domain (Sec7d) found in all ARF‐guanine nucleotide exchange factor proteins. Post‐ER trafficking is rapidly inactivated in sec7‐4 mutant yeast at the restrictive temperature. This conditional defect prevented the normal production of VTCs and instead generated Golgi‐like tubes emanating from the ER exit sites. These tubes progressively developed into stacked cisternae defining the landmark sec7 mutant phenotype. Consistent with the in vivo results, a Sec7d peptide inhibited ER‐to‐Golgi transport and displaced Sec7p from its membrane anchor in vitro. The similarities in the consequences of inactivating Sec7p or ARFs in vivo was revealed by genetic disruption of yeast ARFs or by addition of brefeldin A (BFA) to whole cells. These treatments, as in sec7‐4 yeast, affected the morphology of membrane compartments in the ER‐Golgi transition. Further evidence for Sec7p involvement in the transition for Golgi biogenesis was revealed by in vitro binding between distinct domains of Sec7p with ARFs, COPI and COPII coat proteins. These results suggest that Sec7p coordinates membrane transitions in Golgi biogenesis by directing and scaffolding the binding and disassembly of coat protein complexes to membranes, both at the VTC transition from ER exit sites to form Golgi elements and for later events in Golgi maturation.
Pep12p is a Multifunctional Yeast Syntaxin that Controls Entry of Biosynthetic, Endocytic and Retrograde Traffic into the Prevacuolar Compartment
Authors: Gerrard Sonja R. , Levi Boaz P. , Stevens Tom H.
Published: March 2003

Delivery of proteins to the vacuole of the yeast Saccharomyces cerevisiae requires the function of the endosomal syntaxin, Pep12p. Many vacuolar proteins, such as the soluble vacuolar hydrolase, carboxypeptidase Y (CPY), traverse the prevacuolar compartment (PVC) en route to the vacuole. Here we show that deletion of the carboxy‐terminal transmembrane domain of Pep12p results in a temperature‐conditional block in transport of CPY to the PVC. The PVC also receives traffic from the early endosome and the vacuole, and mutation in PEP12 also blocks these other trafficking pathways into the PVC. Therefore, Pep12p is a multifunctional syntaxin that is required for all known trafficking pathways into the yeast PVC. Finally, we found that the internalized pheromone receptor, Ste3p, can cycle out of the PVC in a VPS27‐independent fashion.
Human Cytomegalovirus Immediate Early Glycoprotein US3 Retains MHC Class I Molecules by Transient Association
Authors: Gruhler Albrecht , Peterson Per A. , Früh Klaus
Published: March 2003

Human cytomegalovirus (HCMV) interferes with major histocompatibility complex (MHC) class I antigen presentation by a sequential multistep process to escape T cell surveillance. During the immediate early phase of infection, the glycoprotein US3 prevents intracellular transport of MHC class I molecules. Interestingly, US3 displays a significantly shorter half‐life than US3‐retained MHC class I molecules. Here we show that US3 associates only transiently with MHC class I molecules, exits the ER, and is inefficiently retrieved from the Golgi. US3 was degraded in a post‐Golgi compartment, most likely lysosomes, because: i) Brefeldin A treatment prolonged the half‐life of US3; and ii) US3 co‐localized with the lysosomal marker protein LAMP in chloroquine‐treated cells. In contrast, MHC class I molecules remained stable in the ER. Upon inhibition of protein synthesis MHC class I molecules were released suggesting that a continuous supply of newly synthesized US3 molecules is required for inhibition of transport. Thus, US3 does not seem to retain MHC class I molecules by a retrieval mechanism. Instead, our observations are consistent with US3 preventing MHC class I trafficking by blocking forward transport.
Traffic COPs of the Early Secretory Pathway
Authors: Barlowe Charles
Published: March 2003

Intracellular transport between the endoplasmic reticulum and Golgi compartments is mediated by coat protein complexes (COPI and COPII) that form transport vesicles and collect the desired set of cargo. Although the COPI and COPII coats are molecularly distinct, a number of mechanistic parallels appear to be emerging, most notably a general role for small guanine triphosphatases in co‐ordinating coat assembly with cargo selection. A combination of morphological, biochemical, and genetic methods is revealing a very dynamic relationship between these compartments, and highlights a central role for COPs in directing traffic through the early secretory pathway. This review focuses on recent advances in molecular mechanisms underlying coated‐vesicle assembly and connections with cellular structures.
Strategies for Prokaryotic Expression of Eukaryotic Membrane Proteins
Authors: Laage Rico , Langosch Dieter
Published: March 2003

High‐level heterologous expression of integral membrane proteins at full‐length is a useful tool for their structural and functional characterization. Here, systems that have previously been used for efficient bacterial expression of eukaryotic membrane proteins are reviewed and novel vectors consisting of a modular fusion moiety based on nuclease A from Staphylococcus aureus are presented.
Floating the Raft Hypothesis for Immune Receptors: Access to Rafts Controls Receptor Signaling and Trafficking
Authors: Dykstra Michelle L. , Cherukuri Anu , Pierce Susan K.
Published: March 2003

The B cell antigen receptor (BCR) is a member of an important family of multichain immune recognition receptors, which are complexes composed of ligand‐binding domains associated with signal‐transduction complexes. The signaling components of these receptors have no inherent kinase activity but become tyrosine phosphorylated in their cytoplasmic domains by Src‐family kinases upon oligomerization, thus initiating signaling cascades. The BCR is unique in this family in that, in addition to its signaling function, it also serves to deliver antigen to intracellular compartments where the antigen is processed and presented bound to major histocompatibility complex (MHC) class II molecules. Recent evidence indicates that both the signaling and antigen‐trafficking functions of the BCR are regulated by cholesterol‐ and sphingolipid‐rich plasma membrane microdomains termed rafts. Indeed, upon oligomerization, the BCR translocates into rafts that concentrate the Src‐family kinase Lyn and is subsequently internalized directly from the rafts. Thus, translocation into rafts allows the association of the oligomerized BCR with Lyn and the initiation of both signaling and trafficking. Significantly, the access of the BCR to rafts appears to be controlled by a variety of B lymphocyte co‐receptors, as well as factors including the developmental state of the B cell and viral infection. Thus, the translocation of the immune receptors into signaling‐competent microdomains may represent a novel mechanism to initiate and regulate immune‐cell activation.
Vrp1p Functions in Both Actomyosin Ring‐Dependent and Hof1p‐Dependent Pathways of Cytokinesis
Authors: Naqvi Suniti N. , Feng Qian , Boulton Victoria J. , Zahn Regina , Munn Alan L.
Published: March 2003

Vrp1p/verprolin/End5p is a Saccharomyces cerevisiae proline‐rich protein, structurally and functionally related to human Wiskott–Aldrich syndrome protein‐interacting protein. Vrp1p is required for viability at 37°C, but not 24°C. Here, we show that loss of Vrp1p (vrp1Δ) leads to a 3–4‐fold delay in cytokinesis, wide bud necks, abnormal actomyosin rings, and aberrant septa even at 24°C. Like other mutations affecting the actomyosin ring, vrp1Δ is synthetic lethal with deletion of HOF1 (or CYK2), which encodes a protein related to mammalian proline serine threonine phosphatase‐interacting protein and Schizosaccharomyces pombe Cdc15p required for an actomyosin ring‐independent pathway of cytokinesis in S. cerevisiae. At 37°C, vrp1Δ cells rapidly cease dividing and exhibit a novel terminal phenotype: a single large bud, two well‐separated nuclei, and an interphase microtubule array. The arrested cells have a persistent ring containing both actin and myosin at the bud neck. Many also exhibit some polarisation of cortical actin patches to the bud neck. Vrp1p binds an SH3‐domain‐containing fragment of Hof1p in vitro. Vrp1p is required in vivo for Hof1p relocalisation to a single ring at the bud neck prior to cytokinesis at 37°C, but not at 24°C. Vrp1p thus acts in both actomyosin ring formation and function, as well as in Hof1p localisation during cytokinesis.
The Mammalian Guanine Nucleotide Exchange Factor mSec12 is Essential for Activation of the Sar1 GTPase Directing Endoplasmic Reticulum Export
Authors: Weissman Jacques T. , Plutner H. , Balch William E.
Published: March 2003

The Sar1 GTPase is an essential component of COPII vesicle coats involved in export of cargo from the endoplasmic reticulum of mammalian cells. To begin to elucidate its mechanism of action, we now report the identity of the mammalian homolog to the yeast Sec12 guanine nucleotide exchange factor (18% identity) that promotes Sar1 activation. Mammalian Sec12 (mSec12) is a type II transmembrane protein with a large cytosolic domain, a fragment of which has previously been reported as the transcription factor prolactin regulatory element binding protein (PREB). mSec12 promotes efficient guanine nucleotide exchange on Sar1, but not Arf1 or Rab GTPases. mSec12 is localized to the endoplasmic reticulum and an antibody to the cytosolic domain of mSec12 potently inhibits Sar1 recruitment and the formation of COPII vesicles in vitro. The dominant negative GDP‐restricted mutant Sar1[T39N] is shown to be a potent inhibitor of mSec12 activity, consistent with its role in preventing COPII vesicle formation in vitro and during transient expression in vivo. We propose that mSec12 is an evolutionarily distant guanine nucleotide exchange factor directing Sar1 GTPase activation in mammalian cells. Its divergence from yeast Sec12p may reflect the specialized needs of the mammalian endoplasmic reticulum involving the formation of Sar1‐dependent transitional elements (Aridor M, et al. J Cell Biol 2001;152:213–229) and selection of cargo into prebudding complexes.
The Dictyostelium LvsA Protein is Localized on the Contractile Vacuole and is Required for Osmoregulation
Authors: Gerald Noel J. , Siano Michael , De Lozanne Arturo
Published: March 2003

LvsA is a Dictyostelium protein that is essential for cytokinesis and that is related to the mammalian beige/LYST family of proteins. To better understand the function of this novel protein family we tagged LvsA with GFP using recombination techniques. GFP‐LvsA is primarily associated with the membranes of the contractile vacuole system and it also has a punctate distribution in the cytoplasm. Two markers of the Dictyostelium contractile vacuole, the vacuolar proton pump and calmodulin, show extensive colocalization with GFP‐LvsA on contractile vacuole membranes. Interestingly, the association of LvsA with contractile vacuole membranes occurs only during the discharge phase of the vacuole. In LvsA mutants the contractile vacuole becomes disorganized and calmodulin dissociates from the contractile vacuole membranes. Consequently, the contractile vacuole is unable to function normally, it can swell but seems unable to discharge and the LvsA mutants become osmosensitive. These results demonstrate that LvsA can associate transiently with the contractile vacuole membrane compartment and that this association is necessary for the function of the contractile vacuole during osmoregulation. This transient association with specific membrane compartments may be a general property of other BEACH‐domain containing proteins.
Peroxisome Remnants in pex3Δ Cells and the Requirement of Pex3p for Interactions Between the Peroxisomal Docking and Translocation Subcomplexes
Authors: Hazra Partha P. , Suriapranata Ivet , Snyder William B. , Subramani Suresh
Published: March 2003

During peroxisomal matrix protein import, the peroxisomal targeting signal receptors recognize cargo in the cytosol and interact with docking and translocation subcomplexes on the peroxisomal membrane. Using immunoprecipitations of multiple protein components, we show that in Pichia pastoris the docking subcomplex consists of the unique peroxins Pex13p, Pex14p and Pex17p, whereas the putative translocation subcomplex has all three RING‐finger peroxins, Pex2p, Pex10p and Pex12p, as unique constituents. We identify Pex3p as a shared component of both subcomplexes. In pex3Δ cells, the unique constituents of the docking subcomplex interact as they do in wild‐type cells, but the assembly of the translocation subcomplex is impaired and its components are present at reduced levels. Furthermore, several interactions detected in wild‐type cells between translocation and docking subcomplex components are undetectable in pex3Δ cells. Contrary to previous reports, pex3Δ cells have peroxisome remnants that pellet during high‐speed centrifugation, associate with membranes on floatation gradients and can be visualized by deconvolution microscopy using antibodies to several peroxins which were not available earlier. We discuss roles for Pex3p in the assembly of specific peroxisomal membrane protein subcomplexes whose formation is necessary for matrix protein import.
Membrane Trafficking During Plant Cytokinesis
Authors: Bednarek Sebastian Y. , Falbel Tanya G.
Published: March 2003

Plant morphogenesis is regulated by cell division and expansion. Cytokinesis, the final stage of cell division, culminates in the construction of the cell plate, a unique cytokinetic membranous organelle that is assembled across the inside of the dividing cell. Both during cell‐plate formation and cell expansion, the secretory pathway is highly active and is polarized toward the plane of division or toward the plasma membrane, respectively. In this review, we discuss results from recent genetic and biochemical research directed toward understanding the molecular events occurring during cytokinesis and cell expansion, including data supporting the idea that during cytokinesis one or more exocytic pathways are polarized toward the division plane. We will also highlight recent evidence for the roles of secretory vesicle transport and cytoskeletal machinery in cell‐plate membrane trafficking and fusion.
Protein Structure and Import Into the Peroxisomal Matrix
Authors: Brocard Cécile B. , Jedeszko Christopher , Song Hong Chang , Terlecky Stanley R. , Walton Paul A.
Published: March 2003

Proteins destined for the peroxisomal matrix are synthesized in the cytosol, and imported post‐translationally. It has been previously demonstrated that stably folded proteins are substrates for peroxisomal import. Mammalian peroxisomes do not contain endogenous chaperone molecules. Therefore, it is possible that proteins are required to fold into their stable, tertiary conformation in order to be imported into the peroxisome. These investigations were undertaken to determine whether proteins rendered incapable of folding were also substrates for import into peroxisomes. Reduction of albumin resulted in a less compact tertiary structure as measured by analytical centrifugation. Microinjection of unfolded albumin molecules bearing the PTS1 targeting signal resulted in their import into peroxisomes. Kinetic analysis indicated that native and unfolded molecules were imported into peroxisomes at comparable rates. While import was unaffected by treatment with cycloheximide, hsc70 molecules were observed to be imported along with the unfolded albumin molecules. These results indicate that proteins, which are incapable of assuming their native conformation, are substrates for peroxisomal import. When combined with previous observations demonstrating the import of stably folded proteins, these results support the model that tertiary structure has no effect on protein import into the peroxisomal matrix.
Current issues in Sjögren's syndrome
Authors: Jonsson Roland , Moen Ketil , Vestrheim Didrik , Szodoray Peter
Published: March 2003

Sjögren's syndrome is a chronic autoimmune and rheumatic disorder with prominent sicca complaints from the mucous membranes because of lack of proper exocrine secretions. There is no straightforward and simple diagnostic test for Sjögren's syndrome, although several classification criteria have been designed including several oral diagnostic tests. A new set of classification criteria in a joint effort by research groups in Europe and USA has recently been presented. A large number of autoantibodies have been reported in Sjögren's syndrome where, in some cases, the antibodies are correlated with the extent and severity of disease. The finding of serum autoantibodies directed against the muscarinic M3 receptor is an important advance in understanding the pathogenesis of not only the impaired glandular function but also associated features of autonomic dysfunction in some patients. The treatment of primary Sjögren's syndrome is still mainly symptomatic.
Oral leishmaniasis in a HIV‐positive patient. Report of a case involving the palate
Authors: Milián MA , Bagán JV , Jiménez Y , Pérez A , Scully C
Published: March 2003

Leishmaniasis is a parasitic disease caused by a protozoon (Leishmania), with different clinical forms that are endemic in certain countries. The association of this disease in patients who are seropositive to human immunodeficiency virus (HIV) has recently been described. Leishmaniasis can develop in any stage of HIV infection, although the clinical manifestations – and hence the diagnosis – tend to coincide with the periods of maximum immune depression. We present the case of a HIV‐positive, ex‐intravenous drug abuser (in stage B2 of the CDC, 1992) with concomitant hepatitis C infection who presented with palatinal pain and bleeding for the past 2 months. Exploration revealed a vegetating tumoration of the hard palate. Hematoxylin‐eosin and Giemsa staining of the biopsy confirmed the diagnosis of leishmaniasis. The definitive diagnosis was mucocutaneous leishmaniasis (MCL), for a bone marrow aspirate proved negative, and no further lesions could be established. The patient was treated with meglumine antimoniate (Glucantime), followed by improvement of the lesions.
Interactions of the two heads of scallop (Argopecten irradians) heavy meromyosin with actin: influence of calcium and nucleotides
Authors: NYITRAI Miklos , SZENT-GYÖRGYI Andrew G. , GEEVES Michael A.
Published: March 2003

We recently proposed a co-operative model for the influence of calcium and ADP on scallop (Argopecten irradians) muscle heavy meromyosin (scHMM), in which scHMM exists in two conformations (designated ‘off’ and ‘on'), and calcium and ADP are allosteric effectors of the equilibrium between the off and on conformations [Nyitrai, Szent-Gyorgyi and Geeves (2002) Biochem. J. 365, 19—30]. Here we examine the influence of actin on scHMM. In the absence of nucleotide, both heads of scHMM bind very tightly to actin, independent of the presence of calcium. In the absence of calcium, ADP dissociates scHMM from actin completely, and little evidence of ternary complex formation can be found (actin affinity >20μM). The off state of scHMM therefore does not interact with actin. In the presence of calcium, ADP and actin lower each other's affinity for scHMM by 30—50-fold, although both heads remain strongly attached to actin (actin affinity 0.17μM). Detailed analysis suggests that the second head contributes far more to the overall binding energy than is the case for mammalian skeletal muscle HMM. This is consistent with a different stereochemical relationship between the two heads in scallop and mammalian HMM molecules.
Photolabelling the rat urotensin II/GPR14 receptor identifies a ligand-binding site in the fourth transmembrane domain
Authors: BOUCARD Antony A. , SAUVÉ Simon S. , GUILLEMETTE Gaétan , ESCHER Emanuel , LEDUC Richard
Published: March 2003

A urotensin II (U-II) peptide analogue containing the photoreactive p-benzoyl-l-phenylalanine (Bz-Phe) in the sixth position was used to identify ligand-binding sites of the rat U-II receptor, also known as GPR14. [Bz-Phe6]U-II bound the receptor expressed in COS-7 cells with high affinity (IC50 0.7nM) and was as potent as U-II in the agonist-induced production of inositol phosphate. Photolabelling of the U-II receptor with 125I-[Bz-Phe6]U-II resulted in the specific formation of a glycosylated 125I-[Bz-Phe6]U-II—U-II receptor complex of 60kDa. Digestion of the 60kDa complex with endoproteinase Glu-C generated a fragment of 17kDa circumscribing the labelled fragment to residues 148—286. Digestion of the ligand—receptor complex with endoproteinase Arg-C produced a short peptide of 4kDa corresponding to fragments 125—148, 167—192 or 210—233. CNBr treatment of the endoproteinase-Glu-C and -Arg-C fragments yielded 2kDa fragments, defining the labelling site to methionine residues 184/185 of the fourth transmembrane domain. Photolabelling of two mutant receptors, M184L/M185L and M184A/M185A, led to a significant decrease in the overall yield of covalent labelling. Taken together, our results indicate that position 6 of U-II normally occupied by phenylalanine would interact with Met184 and/or Met185 of the fourth transmembrane domain of the U-II receptor. This information should be of significant value in the study of the interactions between U-II and its cognate receptor.
A Progestin Antagonist Blocks Vaginocervical Stimulation‐Induced Fos Expression in Neurones Containing Progestin Receptors in the Rostral Medial Preoptic Area
Authors: Blaustein J. D. , Gréco B.
Published: March 2003

Vaginocervical stimulation (VCS) has a variety of effects on the brain, physiology and behaviour. Previous work demonstrated that a progestin antagonist blocked neuronal response to VCS (i.e. Fos expression) in the absence of progesterone in some neurones, and suggested that some of the effects of VCS on the brain are mediated by ligand‐independent activation of progestin receptors (PRs). Although it had been reported previously that some of the cells in which VCS induces Fos expression also contain PRs, it had not been determined if a progestin antagonist blocked Fos expression in these particular neurones. The purpose of this experiment was to determine if a progestin antagonist decreases Fos expression specifically in cells that also express PRs in the preoptic area and ventromedial hypothalamus. As has been shown previously, VCS increased Fos‐immunoreactive (ir) expression in the particular areas studied. In the rostral medial preoptic area, VCS increased Fos expression in cells that coexpressed PRs, as well as in cells that do not. However, in the caudal medial preoptic area, VCS only increased Fos expression in cells that did not coexpress PRs. Injection of the progestin antagonist, RU 486, decreased Fos expression in the rostral, but not caudal medial preoptic area, and it decreased Fos expression only in cells that coexpressed PR‐ir. In contrast to a previous report, in the present study, the progestin antagonist did not inhibit VCS‐induced Fos expression in the ventromedial hypothalamic area. The results of this experiment suggest that the progestin antagonist inhibits VCS‐induced Fos expression in some neurones by blocking PRs, and they provide further support for the idea that VCS influences neuronal response in some cells by ligand‐independent activation of PRs in those cells.
Cellular responses to elevated light levels in Fucus spiralis embryos during the first days after fertilization
Authors: Coelho S. , Rijstenbil J. W. , Sousa‐Pinto I. , Brown M. T.
Published: March 2003

Cellular responses of 1‐, 2‐ and 4‐d‐old Fucus spiralis embryos subjected to a single dose of elevated photosynthetically active photon flux density (PPFD), with or without ultraviolet (UV) radiation, were investigated by measuring the effects on the effective quantum yield of photosystem II (ΔF / Fm′) and intracellular production of active oxygen species (AOS). Production of AOS was determined by the in vivo conversion of 5‐(and‐6)‐chloromethyl‐2′,7′‐dichlorodihydrofluorescein diacetate (CM‐DCFH2‐DA) to the fluorescent compound dichlorofluorescein (DCF) using confocal laser scan microscopy (CLSM) and image analysis. The role of xanthophyll cycle pigments in photoprotection was also assessed. A rapid decline in ΔF / Fm′ was observed under all elevated light conditions. A correlation was found between non‐photochemical quenching and the de‐epoxidation ratio zeaxanthin/(zeaxanthin + violoxanthin). Active oxygen formation increased with PPFD and was higher in older embryos and when UVB was present. Two photoinhibition responses were recognized: (i) a rapid decline of the PSII yield due to the violoxanthin–zeaxanthin cycle (photoprotection), and (ii) a slower second‐phase decline, correlated with active oxygen production. Electron transport rate (ETR) increased with embryo age, and was correlated with AOS production. As a result of enhanced AOS production, there was a slow recovery of the PSII yield, in particular with increased effective UV dose. In general, embryos were able to recover from the imposed light conditions, but UVB had a more damaging effect. Overall, our data suggest that under natural conditions, embryos of F. spiralis are susceptible to elevated light levels, and that UVB radiation is an important stress factor.
High salt‐treatment‐induced Na+ extrusion and low salt‐treatment‐induced Na+ accumulation in suspension‐cultured cells of the mangrove plant, Bruguiera sexangula
Authors: Kura‐Hotta M. , Mimura M. , Tsujimura T. , Washitani‐Nemoto S. , Mimura T.
Published: March 2003

A suspension‐cultured cell strain of the mangrove plant (Bruguiera sexangula) was established from a callus culture and maintained in an amino acid medium in the absence of NaCl. NaCl non‐adapted cells were transferred to media containing 0–200 mm NaCl. The initial growth rate decreased gradually with increasing salt concentrations. However, at up to 150 mm NaCl, cell number growth at the highest point was almost the same as that at lower salt concentrations. Cells even continued to grow in the presence of 200 mm NaCl.

Cells incubated in a medium containing 50 mm NaCl for 3 weeks accumulated Na+, while those incubated in 150 mm NaCl for 2 d showed only a transient increase in Na+ and Cl– concentrations. In the latter treatment, the intracellular concentration of Na+ returned to the original low level within 2 weeks. It took a longer time for Cl– to return to its original level. As a result, the Na+ and Cl– concentrations in cells cultured with 50 mm NaCl were much larger than those in cells cultured with 150 mm NaCl. The intracellular distribution of ions after transfer to the medium containing 150 mm NaCl was analysed by isolating the vacuoles.

Treatment with amiloride, an inhibitor of the Na+/H+ antiporter, suppressed the recovery of Na+ to the original level in the cells. Treatment with 150 mm NaCl for 3 d stimulated the activities of both the vanadate‐dependent H+‐ATPase and the Na+/H+ antiporter in the plasma membrane fraction.
Mercury‐induced genes in Arabidopsis thaliana: identification of induced genes upon long‐term mercuric ion exposure
Authors: Heidenreich B. , Mayer K. , Sandermann H. , Ernst D.
Published: March 2003

Mercuric‐ion‐induced gene expression was studied in Arabidopsis thaliana Columbia wild type. Rosettes of plants grown for 21 d on agar medium supplemented with 20, 30 and 40 µm HgCl2 were pooled and used to isolate cDNAs of induced genes by suppression subtractive hybridization. Of the 576 clones isolated initially, 31 turned out to be mercury‐induced by Northern hybridization. However, kinetic studies using cDNA arrays clearly showed that seven genes were exclusively mercuric‐ion‐induced, 14 were induced by mercury but also affected by a diurnal rhythm, and 10 clones were only modulated by the day–night cycle. The expression levels of the metal‐induced genes increased from 1·5‐fold to 10‐fold. Functional classification resulted in genes encoding proteins for the photosynthetic apparatus and for the antioxidative system. In addition, unexpected genes, whose connection to mercury ion stress is not evident, were identified.
Atmospheric CO2 concentration does not directly affect leaf respiration in bean or poplar
Authors: Jahnke S.
Published: March 2003

It is a matter of debate if there is a direct (short‐term) effect of elevated atmospheric CO2 concentration (Ca) on plant respiration in the dark. When Ca doubles, some authors found no (or only minor) changes in dark respiration, whereas most studies suggest a respiratory inhibition of 15–20%. The present study shows that the measurement artefacts – particularly leaks between leaf chamber gaskets and leaf surface, CO2 memory and leakage effects of gas exchange systems as well as the water vapour (‘water dilution’) effect on DCO2 measurement caused by transpiration – may result in larger errors than generally discussed. A gas exchange system that was used in three different ways – as a closed system in which Ca increased continuously from 200 to 4200 mmol (CO2) mol‐1 (air) due to respiration of the enclosed leaf; as an intermittently closed system that was repeatedly closed and opened during Ca periods of either 350 or 2000 mmol mol‐1, and as an open system in which Ca varied between 350 and 2000 mmol mol‐1– is described. In control experiments (with an empty leaf chamber), the respective system characteristics were evaluated carefully. When all relevant system parameters were taken into account, no effects of short‐term changes in CO2 on dark CO2 efflux of bean and poplar leaves were found, even when Ca increased to 4200 mmol mol‐1. It is concluded that the leaf respiration of bean and poplar is not directly inhibited by elevated atmospheric CO2.
Rapid, reversible alterations in spinach thylakoid appression upon changes in light intensity
Authors: Rozak P. R. , Seiser R. M. , Wacholtz W. F. , Wise R. R.
Published: March 2003

Changes in light quantity and quality cause structural changes within the thylakoid membrane; long‐term responses have been described for so‐called ‘sun’ and ‘shade’ leaves. Many leaves, however, experience changes in irradiance on a time scale of minutes due to self‐shading and sun flecks. In this study, mature, attached spinach leaves were grown at 300 µmol photons m−2 s−1then rapidly switched to a different light treatment. The treatment irradiances were 10, 800 or 1500 µmol m−2 s−1for 10 min, or 10 or 20 min of self‐shading (about 10 µmol m−2 s−1). Image analysis of transmission electron micrographs revealed that a 10 min switch to a lower light intensity increased grana size and number per chloroplast profile by 10–20%. Returning the leaves to 300 µmol m−2 s−1for 10 min reversed the phenomenon. Chlorophyll fluorescence measurements of detached, intact leaves at 77 K were suggestive of a transition from state 2 to state 1 upon shading. Diurnal ultrastructural measurements of granal size and number did not reveal a significant net change in ultrastructure over the time scale of hours. It is concluded that spinach chloroplasts can alter the degree of thylakoid appression in response to irradiance changes on a time scale of minutes. These ultrastructural responses are caused by biochemical and biophysical adjustments within the thylakoid membrane that serve to maximize photosynthesis and minimize photo‐inhibition under rapidly fluctuating light environments.
Consequences of root growth kinetics and vascular structure on the distribution of lateral roots
Authors: Draye X.
Published: March 2003

It has been proposed that the acropetal initiation of lateral roots is a built‐in process specified as part of the general process of cell division and differentiation in the parent root tip. Conversely, it is commonly reported that root branching is essentially a variable feature. In the present study, the interlateral distance along the parent root has been investigated using three banana varieties (Musa spp.) grown in two substrates. The pattern of lateral root initiation was obscured by variations of root growth patterns and vascular structure among roots, genotypes and substrates. A framework model is formulated showing the influence of growth pattern and vascular structure on branching density. The model raises a distinction between growth components which should not affect the branching density (i.e. rate of cell division) and which may affect it (i.e. size of mature cells and number of transverse divisions performed by cells executing their trajectory in the meristem). It appears also that lateral root density and root growth rate might be independently modulated by appropriate changes of root growth patterns, in banana and presumably many other taxa.
Control of chemokine production at the blood–retina barrier
Authors: Crane I. J. , Wallace C. A. , Mckillop‐Smith S. , Forrester J. V.
Published: March 2003

Chemokine production at the blood–retina barrier probably plays a critical role in determining the influx of tissue‐damaging cells from the circulation into the retina during inflammation. The blood–retina barrier comprises the retinal microvascular endothelium and the retinal pigment epithelium. Chemokine expression and production by human retinal microvascular endothelial cells (REC) have never been reported previously, so we examined the in vitro expression and production of monocyte chemoattractant protein‐1 (MCP‐1), regulated on activation of normal T‐cell expressed and secreted (RANTES), macrophage inflammatory protein (MIP)‐1α, MIP‐1β, interleukin (IL)‐8, epithelial cell‐derived neutrophil activating protein‐78 (ENA‐78) and growth related oncogene α (GROα) in these cells, both unstimulated and stimulated by cytokines likely to be present during the evolution of an inflammatory response. We compared this to expression and production of these chemokines in vitro in human retinal pigment epithelial cells (RPE). MCP‐1 was expressed and produced constitutively by REC but all the chemokines were produced in greater amounts upon stimulation with the proinflammatory cytokines IL‐1β and tumour necrosis factor‐α (TNF‐α). MCP‐1 and IL‐8 were produced at much higher levels than the other chemokines tested. MIP‐1α and MIP‐1β were present only at low levels, even after stimulation with IL‐1β and TNF‐α. Cytokines with greater anti‐inflammatory activity, such as IL‐4, IL‐10, IL‐13, transforming growth factor‐β (TGF‐β) and IL‐6, had little effect on chemokine production either by REC alone or after stimulation with IL‐1β and TNF‐α. RPE, although a very different cell type, showed a similar pattern of expression and production of chemokines, indicating the site‐specific nature of chemokine production. Chemokine production by REC and RPE is probably significant in selective leucocyte recruitment during the development of inflammation in the retina.
Diversity in MHC class II antigen presentation
Authors: Robinson John H. , Delvig Alexei A.
Published: March 2003

Processing exogenous and endogenous proteins for presentation by major histocompatibility complex (MHC) molecules to T cells is the defining function of antigen‐presenting cells (APC) as major regulatory cells in the acquired immune response. MHC class II‐restricted antigen presentation to CD4 T cells is achieved by an essentially common pathway that is subject to variation with regard to the location and extent of degradation of protein antigens and the site of peptide binding to MHC class II molecules. These subtle variations reveal a surprising flexibility in the ways a diverse peptide repertoire is displayed on the APC surface. This diversity may have profound consequences for the induction of immunity to infection and tumours, as well as autoimmunity and tolerance.
Effects of food addition on the seasonal density‐ dependent structure of bank vole Clethrionomys glareolus populations
Authors: Yoccoz Nigel G. , Stenseth Nils ChR. , Henttonen Heikki , Prévot‐Julliard Anne‐Caroline
Published: March 2003

Population growth rates of bank vole populations in northern Finland were studied using long‐term Capture–Mark–Recapture (CMR) data from two large grids (food‐addition and control), in 1982–94.

 A marked seasonal structure was found for direct density dependence, with a stronger density dependence in summer than in other seasons. There was no detectable evidence of delayed density dependence, consistent with the disappearance of large periodic multi‐annual fluctuations.

 Food‐addition resulted in higher densities whereas the effect on the seasonal density‐dependent structure was negligible.

 Stability analysis of the deduced population dynamics model suggests that the dynamics were not affected by food addition. Variation in food resources is therefore unlikely to be a direct cause for multi‐annual fluctuations in the studied system. Future studies should aim at linking the seasonal structure in the variation of vital rates to the seasonal structure in population dynamics.