bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of pinealectomy and melatonin on the retrograde degeneration of retinal ganglion cells in a novel model of intraorbital optic nerve transection in mice
Authors: Kilic Ertugrul , Hermann Dirk M. , Isenmann Stefan , Bähr Mathias
Published: March 2003

The effects of pinealectomy and of intraperitoneally administered melatonin on the retrograde degeneration of retinal ganglion cells (RGCs) were examined in a novel model of optic nerve (ON) transection in C57BL/6J mice. RGCs were prelabeled with the fluorescent tracer 1,1′‐dioctadecyl‐3,3,3′,3′‐tetramethyl indocarbocyanine perchlorate (Di‐I), and the ON was cut inside the orbital cavity 7 days later. The degree of RGC injury was assessed by counting viable Di‐I labeled RGCs in various locations of the retina. In unlesioned control eyes, a mean ganglion cell density of 1891 ± 30/mm2 (mean ± S.E.M.) was determined. The cell density markedly declined at 14 days after axotomy (295 ± 9 cells/mm2; 15.6% of contralateral). Sham‐pinealectomy did not influence the density of RGCs at 14 days after ON transection (382 ± 37 cells/mm2). In pinealectomized animals, on the other hand, the RGC number was significantly reduced as compared with untreated and sham‐pinealectomized animals (91 ±  33 RGCs/mm2). The effect of pinealectomy was reversed after i.p. administration of melatonin (4 mg/kg bw bolus followed by continuous infusion of 8 mg/kg bw/day) (286 ± 27 cells/mm2). In nonpinealectomized animals, on the contrary, i.p. melatonin did not influence the RGC density (344 ± 20 cells/mm2). The present results suggest that endogenous melatonin prevents the delayed degeneration of adult central nervous system (CNS) neurons in vivo, and that exogenous substitution of melatonin may be useful to protect injured neurons against cell death under conditions of melatonin deficiency, e.g. in the aged brain, when melatonin synthesis and secretion have decreased.
The chemistry of melatonin's interaction with reactive species
Authors: Allegra M. , Reiter R.J. , Tan D.‐X. , Gentile C. , Tesoriere L. , Livrea M.A.
Published: March 2003

Abstract: Melatonin has been shown to be an effective antioxidant in a number of experimental models both in vitro and in vivo. Considering the data available, it is now clear that the indoleamine is involved in antioxidative mechanisms more complex than originally envisaged. These range from the direct radical scavenging of a variety of radicals and reactive species to the control and/or modulation of a number of processes which may trigger a redox imbalance between antioxidant and prooxidant species. This review focuses on the direct radical scavenging activity of melatonin and provides a summary of the mechanisms of the reactions between the indoleamine and reactive species in pure chemical solutions. These actions likely account for at least some of the protective actions of melatonin under conditions of high oxidative stress.
Motor pattern of the knee joint muscles during side‐step cutting in European team handball
Authors: Bencke J. , Næsborg H. , Simonsen E. B. , Klausen K.
Published: March 2003

The incidence of anterior cruciate ligament (ACL) injuries is reported to be high in many popular team sports. The most risky movement in European team handball is reported to be the side‐step cutting manoeuvre. Well‐rehabilitated ACL‐deficient athletes have been shown to have increased co‐contraction about the knee joint with this manoeuvre. The aim of this study was to examine the effect of a prophylactic training programme on the co‐contraction of the knee joints of non‐injured European team handball players. The subjects performed ‘match‐like’ cutting manoeuvres on a force platform. EMG‐signals from the involved knee joint muscles and force platform signals were simultaneously stored on a personal computer. The data collected before and after a 12‐week prophylactic training program were compared. The results demonstrated that rehabilitation exercises cannot increase co‐contraction about the knee joint in healthy athletes during side‐step cutting. This is contradictory to the reported effect on ACL‐deficient athletes.
Are social classes still relevant to analyse sports groupings in “postmodern” society? An analysis referring to P. Bourdieu’s theory
Authors: Ohl F.
Published: March 2003

P. Bourdieu’s theory will be used to analyse changes in sport sociology. A significant part of the transformation of sociological research depends on the analysis of social categories and particularly of social classes. The theory of P. Bourdieu grants social positions and conditions an important role in the explanation of an agent’s behaviour. The question is to know whether sports groupings, in the so‐called “postmodern” society, can still be analysed with Bourdieu’s sociological frame of analysis. The observation of new forms of sports grouping is used, by some French sociologists, to criticise Bourdieu’s axiomatic. It is argued here that it is more often a misunderstanding or a mechanical use of Bourdieu’s theory which needs to be criticised.
Physical exercise and musculoskeletal pain among forest industry workers
Authors: Miranda H. , Viikari‐Juntura E. , Martikainen R. , Takala E.‐P. , Riihimäki H.
Published: March 2003

The study investigated the relations between physical exercise and musculoskeletal pain among forest industry workers. We studied a population of 3312 Finnish forest industry workers, who replied to a questionnaire survey in 1994 (response rate 77%). The outcome variables in this cross‐sectional study were the number of days with pain in the low back, neck, shoulder and knee during the preceding 12 months. Multivariable logistic regression models were used in statistical analyses. Active walkers had more sciatic pain, active volleyball players had more shoulder pain and those who practiced trekking actively had more knee pain than those who practiced these activities less. The risk of shoulder pain was more than three times higher for those who played volleyball actively compared to those who played less. In addition, age, mental stress and work‐related physical loading were strongly associated with musculoskeletal pain. When studying the relations between physical exercise and musculoskeletal pain in a working population, it is important to not only detect the general physical activity but also to specify the different modes of exercise. In addition, the other factors which are strongly related to pain (such as mental stress and work‐related physical loading) should be taken into account.
Non‐operative treatment regime including eccentric training for lateral humeral epicondylalgia
Authors: Svernlöv B. , Adolfsson L.
Published: March 2003

In a pilot study 38 patients with lateral humeral epicondylalgia were randomly allocated to two treatment groups. Group S (stretching) was treated with a contract‐relax‐stretching program while group E (eccentric exercise) underwent an eccentric exercise program. Both groups also received forearm bands and wrist support nightly. The programs were carried out daily at home during 12 weeks. Evaluation before and 3, 6 and 12 months after treatment, included subjective assessment of symptoms using visual analogue scales and grip strength measurements. Thirty‐five patients were available for follow‐up. Five patients, three in group S and two in group E, did not complete the programs due to increased pain while 30 (86%) reported complete recovery or improvement. Reduced pain and increased grip strength were seen in both treatment groups but 12 out of 17 patients (71%) in group E rated themselves as completely recovered as compared to 7 out of 18 (39%) in group S (P=0.09), and in group E the increase in grip strength after 6 months was statistically significantly larger than in group S. In a second study the eccentric training regime was used in a consecutive series of 129 patients with lateral epicondylalgia. The patients were divided into two groups with one group consisting of patients with less than one year duration of symtoms and the other comprised patients with a duration of symptoms for more than one year. The results of treatment were evaluated in the same way as in the pilot study, and also after 3.4 years using the scoring system by Verhaar et al. At the end of the treatment period statistically significant improvements were seen in all VAS recordings and in grip strength. After 3.4 years 38% had excellent, 28% good, 25% fair and 9% poor results according to the score. In the self‐rated outcome 54% regarded themselves as completely recovered, 43% improved, 2% unchanged and 2% worse. No significant differences were seen between patients with a duration of symptoms for more than one year compared to patients with symptoms for less than one year. The eccentric training regime can considerably reduce symptoms in a majority of patients with lateral humeral epicondylalgia, regardless of duration, and is possibly superior to conventional stretching.
Ammonia threshold—comparison to lactate threshold, correlation to other physiological parameters and response to training
Authors: Yuan Y. , So R. , Wong S. , Chan K. M.
Published: March 2003

During standard graded exercise, blood lactate and blood ammonia levels increase in parallel and the two thresholds appear at the same relative intensity. The first part of this study aimed at comparing ammonia threshold to lactate threshold with five different graded exercise protocols. A significant difference between the two thresholds was found only in the continuous protocol with 4‐min steps in which ammonia threshold appeared at a higher intensity than lactate threshold. The second part of the study investigated the correlation of ammonia threshold to some common physiological measurements. Correlation was significant with lactate threshold, ventilation threshold and endurance time. No correlation was found the anaerobic power, anaerobic capacity measurement and peak VO2. Ammonia threshold was also studied before and after endurance training and sprint training. The 8‐week endurance training program was able to delay the appearance of ammonia threshold, but not the 8‐week sprint training program. Findings in this study demonstrate that ammonia threshold is a physiological parameter that should be recognized and has potential to be applied for the evaluation of exercise capacity and the effectiveness of endurance training programs.
Stability of leisure‐time physical activity during adolescence—a longitudinal study among 16‐, 17‐ and 18‐year‐old Finnish youth
Authors: Aarnio M. , Winter T. , Peltonen J. , Kujala U. M. , Kaprio J.
Published: March 2003

Participation in physical activity during childhood and adolescence is frequently mentioned as one factor likely to promote a more active lifestyle in adulthood with its health benefits. We studied the changes in leisure‐time physical activity pattern and self‐reported fitness during a three‐year period in adolescence and investigated whether the type of sports has an effect on stability of physical activity at leisure. A questionnaire with identical physical activity items was sent to Finnish twins on their 16th and 17th birthdays and 6 months after the 18th birthday. A total of 1338 boys and 1596 girls responded to all three questionnaires, with response rates of 73.6% and 86.5%. The proportions of very active adolescents and adolescents with very good self‐reported fitness seem to be alike at each age. Among girls, 23.7% to 27.7% reported being very active (4–5 times a week) and 13.7% to 15.1% considered their physical fitness to be very good at the ages of 16, 17 and 18. Among boys, the comparable percentages were 31.5% to 35.5% and 30.6% to 34.4%. However, the longitudinal three‐year follow up showed substantial changes over time among individuals from one physical activity group to another. Only 19.1% of boys and 11.2% of girls were persistent exercisers (i.e., very active on all three years) and 15.6% of boys and 5.1% of girls were persistently fit (i.e., very good self‐reported fitness on all three years). Stability of leisure‐time physical activity was highest among those who participated in several different types of sports. Among boys the proportion of persistent exercisers was highest for those who participated in cross‐country skiing, jogging and body‐building (22.0–41.5%) and among girls for those who participated in ball games (11.9–28.6%). Those who participated in organised sports were more often persistent exercisers than those who did not (odds ratio = 13.2 for boys (CI 9.4–18.7) and 8.9 for girls (CI 6.4–12.5)). Also, those who participated in organised sports were more often persistently fit (odds ratio = 7.3 for boys (CI 5.2–10.2) and 10.4 for girls (CI 6.4–16.9). Adolescents are recommended to participate in and try different types of sports, and especially for girls ball games would appear to favour long‐term maintenance of leisure‐time physical activity.
Erythropoietin concentrations and isoforms in urine of anonymous Olympic athletes during the Nagano Olympic Games
Authors: Berglund B. , Wide L.
Published: March 2003

The ordinary doping control urine samples of 36 anonymous participants (cross‐country skiers, biathlon athletes, and curling athletes) of the 1998 Nagano Olympic Games were analyzed for erythropoietin and erythropoietin isoforms. The urine erythropoietin concentration (IU/l) was determined with a competitive radioimmunoassay method and the isoforms were studied by electrophoresis and given as milli albumin mobility units (mAMU). Erythropoietin was detectable in 23 out of 36 specimens (64%). The biathlon and curling athletes had similar urine concentration of erythropoietin. The group of 16 cross‐country skiers had significantly (P < 0.05) increased urine concentration of erythropoietin as compared to curling athletes and four of them had urine erythropoietin concentrations between 3.6 and 5.1 IU/l. The electrophoretic mobility of erythropoietin was determined in all eight samples with urine concentration of erythropoietin of more than 2 (range 2.1–5.1) IU/l. No single urine specimen with a median erythropoietin electrophoretic mobility below the cut‐off level of 670 mAMU (indicative of doping with recombinant erythropoietin) was registered. Erythropoietin in urine was detected in 71% and the isoforms of Epo characterized in 29% of the anonymous Olympic endurance athletes. The urine concentration of erythropoietin in the biathlon and curling athletes were similar to those of non‐athletes. The group of cross‐country skiers had higher levels of erythropoietin in urine. These higher levels of urine erythropoietin in cross‐country skiers are partly due to more concentrated urine specimens.
Timing of post‐exercise protein intake is important for muscle hypertrophy with resistance training in elderly humans
Authors: Esmarck B. , Andersen J. L. , Olsen S. , Richter E. A. , Mizuno M. , Kjaer M.
Published: March 2003

(1) Age‐associated loss of skeletal muscle mass and strength can partly be counteracted by resistance training, causing a net synthesis of muscular proteins. Protein synthesis is influenced synergistically by post‐exercise amino acid supplementation, but the importance of the timing of protein intake remains unresolved. (2) The study investigated the importance of immediate (P0) or delayed (P2) intake of an oral protein supplement upon muscle hypertrophy and strength over a period of resistance training in elderly males. (3) Thirteen men (age 74 ± 1 years; body mass index (BMI), 25 ± 1 kg m− 2 (means ± SEM)) completed a 12‐week resistance training program (three times per week) receiving oral protein in liquid form (10 g protein, 7 g carbohydrate, 3 g fat) immediately after (P0) or 2 h after (P2) each training session. Muscle hypertrophy was evaluated by magnetic resonance imaging (MRI) and from muscle biopsies and muscle strength was determined using dynamic and isokinetic strength measurements. Body composition was determined from dual‐energy X‐ray absorptiometry (DEXA) and food records were obtained over 4 days. The plasma insulin response to protein supplementation was also determined. (4) In response to training, the cross‐sectional area of m. quadriceps femoris (54.6 ± 0.5–58.3 ± 0.5 cm2) and mean fiber area (4047 ± 320–5019 ± 615 μ m2) increased in the P0 group, whereas no significant increase was observed in P2. For P0 both dynamic and isokinetic strength increased, by 46 and 15%, respectively (P < 0.05), whereas P2 only improved in dynamic strength, by 36% (P < 0.05). No differences in glucose or insulin response were observed between protein intake at 0 and 2 h post‐exercise. (5) We conclude that early intake of an oral protein supplement after resistance training is important for the development of hypertrophy in skeletal muscle of elderly men in response to resistance training.
Exercise and injury prevention in older people
Authors: Skelton D. A. , Beyer N.
Published: March 2003

This review aims to provide the reader with up to date evidence in relation to the role of exercise in the reduction of risk factors and the prevention of falls and injuries. Falls and injury may lead to a spiral of inactivity and decline that take older people close to or below the critical “thresholds” of performance necessary for everyday activities. Yet, low strength and power, poor balance, poor gait and functional ability, and fear of falling are all risk factors for falls modifiable with tailored exercise. Although the evidence on types, amounts and specificity of exercise to prevent falls is not complete, recommendations have been published that have been effective, either as an exercise stand‐alone intervention or with exercise as part of a multifactorial intervention. It is clear that the target population must be at risk or already fallers, they must be “not too fit” and “not too frail”. Supervised home‐based exercise programs may be effective in those aged over 80 because they fall more frequently, injure more easily, and recover more slowly. In younger, community‐dwelling, fallers multifactorial group interventions including targeting of balance, strength, power, gait, endurance, flexibility, co‐ordination and reaction may be more effective. There are, however, research questions that still need answering – whether there are certain types of exercise harmful in certain subgroups of older people, what is the ideal intensity, frequency and duration of exercise for different subgroups of older people (primary and secondary prevention) and the relative value of the different components of fitness to prevention of falls and injuries. This review highlights the necessity of tailored, specific balance and strength exercise in the multidisciplinary prevention of falls and injuries.
Detection of solid pigment in dermatoscopy images using texture analysis
Authors: Murali Anantha , Stoecker William V. , Moss Randy H.
Published: March 2003

Background/aims: Epiluminescence microscopy (ELM), also known as dermoscopy or dermatoscopy, is a non‐invasive, in vivo technique, that permits visualization of features of pigmented melanocytic neoplasms that are not discernable by examination with the naked eye. ELM offers a completely new range of visual features. One such feature is the solid pigment, also called the blotchy pigment or dark structureless area. Our goal was to automatically detect this feature and determine whether its presence is useful in distinguishing benign from malignant pigmented lesions.

Methods: Here, a texture‐based algorithm is developed for the detection of solid pigment. The factors d and a used in calculating neighboring gray level dependence matrix (NGLDM) numbers were chosen as optimum by experimentation. The algorithms are tested on a set of 37 images. A new index is presented for separation of benign and malignant lesions, based on the presence of solid pigment in the periphery.

Results: The NGLDM large number emphasis N2 was satisfactory for the detection of the solid pigment. Nine lesions had solid pigment detected, and among our 37 lesions, no melanoma lacked solid pigment. The index for separation of benign and malignant lesions was applied to the nine lesions. We were able to separate the benign lesions with solid pigment from the malignant lesions with the exception of only one lesion, a Spitz nevus that mimicked a malignant melanoma.

Conclusion: Texture methods may be useful in detecting important dermatoscopy features in digitized images and a new index may be useful in separating benign from malignant lesions. Testing on a larger set of lesions is needed before further conclusions can be made.
Sea water or its components alter experimental irritant dermatitis in man
Authors: Yoshizawa Yusuke , Tanojo Hanafi , Kim Seong Jin , Maibach Howard I.
Published: March 2003

Background/aims: Ocean bathing has been considered “healthy” for skin, but its efficacy remains testimonial in nature. Our aim was to evaluate the effects of sea water and its main components on experimental irritant contact dermatitis induced by sodium lauryl sulphate (SLS) cumulative irritation.

Methods: After open application of 2% SLS for 10 min on volar forearm sites, solutions of sea water, 500 mM NaCl, 10 mM KCl, 55 mM MgCl2, 10 mM CaCl2, or deionized water were separately applied using filter paper discs for 20 min. The procedures were repeated daily for 2 weeks. The effects of the treatment were assessed daily using measurements of transepidermal water loss (TEWL), as an indicator of epidermal barrier function, and capacitance, as a parameter of stratum corneum water content.

Results: Sea water, NaCl, and KCl significantly inhibited the increase of TEWL as compared with deionized water (P<0.003, P<0.05, P<0.05, respectively). Sea water and NaCl inhibited the decrease of capacitance as well (P<0.03, P<0.01).

Conclusion: The effect of sea water may be attributed to skin barrier preservation by NaCl and KCl, and an emollient effect by NaCl.
Unconventional Myosins: Anchors in the Membrane Traffic Relay
Authors: Tuxworth Richard I. , Titus Margaret A.
Published: March 2003

The family of unconventional myosins is ever growing and the functions attributed to them seem to expand in parallel. These actin‐based motor proteins have been implicated in processes as seemingly diverse as endocytosis and exocytosis, the transport of organelles, in spermatogenesis and in neurosensory functions such as hearing and sight. A common myosin function may underlie them all — the regulation of intracellular membrane traffic.
The Polymerization Motor
Authors: Theriot Julie A.
Published: March 2003

Polymerization and depolymerization of actin filaments and microtubules are thought to generate force for movement in various kinds of cell motility, ranging from lamellipodial protrusion to chromosome segregation. This article reviews the thermodynamic and physical theories of how a nonequilibrium polymerization reaction can be used to transduce chemical energy into mechanical energy, and summarizes the evidence suggesting that actin polymerization produces motile force in several biological systems.
Lipid Metabolism and Regulation of Membrane Trafficking
Authors: Huijbregts Richard P.H. , Topalof Lora , Bankaitis Vytas A.
Published: March 2003

The past 20 years have witnessed tremendous progress in our understanding of the molecular machinery that controls protein and membrane transport between organelles (Scheckman R, Orci L. Coat proteins and vesicle budding. Science 1996;271: 1526–1533 and Rothman JE. Mechanisms of intracellular protein transport. Nature 1994;372: 55–63.) The research efforts responsible for these impressive advances have largely focused on the identification and characterization of protein factors that participate in membrane trafficking events. The role of membranes and their lipid constituents has received considerably less attention. Indeed, until rather recently, popular models for mechanisms of membrane trafficking had relegated membrane lipids to the status of a passive platform, subject to deformation by the action of coat proteins whose polymerization and depolymerization govern vesicle budding and fusion reactions. The 1990s, and particularly its last half, has brought fundamental reappraisals of the interface of lipids and lipid metabolism in regulating intracellular membrane trafficking events. Some of the emerging themes are reviewed here.
Both Calmodulin and the Unconventional Myosin Myr4 Regulate Membrane Trafficking Along the Recycling Pathway of MDCK Cells
Authors: Huber Lukas A. , Fialka Irene , Paiha Karin , Hunziker Walter , Sacks David B. , Bähler Martin , Way Michael , Gagescu Raluca , Gruenberg Jean
Published: March 2003

In epithelial cells, endocytosed transferrin and its receptor, which cycle basolaterally, have been shown to transit through recycling endosomes which can also be accessed by markers internalized from the apical surface. In this work, we have used an in vitro assay to follow transfer of an endocytosed marker from apical or basolateral early endosomes to recycling endosomes labeled with transferrin. We show that calmodulin (CaM) function is necessary for transfer and identified myr4, a member of the unconventional myosin superfamily known to use CaM as a light chain, as a possible target protein for CaM. Since myr4 is believed to act as an actin‐based mechanoenzyme, we tested the role of polymerized actin in the assay. Our data show that conditions which either prevent actin polymerization or induce the breakdown of existing filaments strongly inhibit interactions between recycling endosomes and either set of early endosomes. Altogether, our data indicate that trafficking at early steps of the endocytic pathway in Madin–Darby Canine Kidney cells depends on the actin‐based mechanoenzyme myr4, its light chain CaM, and polymerized actin.
Membrane Fusion Mechanisms: The Influenza Hemagglutinin Paradigm and its Implications for Intracellular Fusion
Authors: Stegmann Toon
Published: March 2003

The mechanism of membrane fusion induced by the influenza virus hemagglutinin (HA) has been extensively characterized. Fusion is triggered by low pH, which induces conformational changes in the protein, leading to insertion of a hydrophobic ‘fusion peptide’ into the viral membrane and the target membrane for fusion. Insertion perturbs the target membrane, and hour glass‐shaped lipidic fusion intermediates, called stalks, fusing the outer monolayers of the two membranes, are formed. Stalk formation is followed by complete fusion of the two membranes. Structures similar to those formed by HA at the pH of fusion are found not only in many other viral fusion proteins, but are also formed by SNAREs, proteins involved in intracellular fusion. Substances that inhibit or promote HA‐induced fusion because they affect stalk formation, also inhibit or promote intracellular fusion, cell–cell fusion and even intracellular fission similarly. Therefore, the mechanism of influenza HA‐induced fusion may be a paradigm for many intracellular fusion events.
How to Convert a Traditional Electron Microscopy Laboratory to Digital Imaging: Follow the ‘Middle Road’
Authors: Heuser John
Published: March 2003

Today, electron microscopy (EM) is increasingly confronted by the revolution in image‐processing technology provoked by modern computers. Digital cameras are fast replacing film‐based cameras in EM, as elsewhere, and the procedures for digital image‐archiving, image‐analysis, and image publication are rapidly evolving. To take advantage of these advances, we have chosen for the moment a ‘middle road’, in which film remains our basic recording medium in the electron microscope, but immediately thereafter, all film‐based images are converted to digital files for further analysis and processing. The rationale behind this approach is that film still offers far greater sensitivity and resolution (providing an image equivalent to> 10 000 pixels per inch in a 1‐s exposure), and film is still far easier to organize and archive than digital images of comparable resolution. However, digital manipulation of EM images has become mandatory. Hence, we explain here, in some detail, how we convert from film to digital.
Gut Thoughts on the Golgi Complex
Authors: Griffiths Gareth
Published: March 2003

The new millennium coincides within 1 year of Camillo Golgi's centennial celebrations. It is quite remarkable that the structure and formation of this organelle is as controversial today as was its mere existence from Golgi's time to the 1950s, when EM approaches were introduced. Since the late 1950s, two opposing models of Golgi structure and function have split the Golgi scientific community, namely vesicular transport versus organelle maturation. Although a few years ago Golgi maturation seemed to be ‘out for the count’, it has recently seen an almost messianic revival. In this review, I argue that this large‐scale desertion from the vesicle transport model to the maturation camp is premature. I propose an alternative, dynamic steady‐state model, in which transient tubular connections function in parallel to vesicular transport and that the biosynthetic pathway is made up of three major distinct compartments: the ER, the Golgi and the TGN.
Overexpression of a Novel Sorting Nexin, SNX15, Affects Endosome Morphology and Protein Trafficking
Authors: Barr Valarie A. , Phillips Susan A. , Taylor Simeon I. , Haft Carol Renfrew
Published: March 2003

Sorting nexin (SNX) 15 is a novel member of the SNX family of proteins. Although the functions of most SNXs have not yet been determined, several family members (e.g., SNX1, SNX2, SNX3, and SNX8) are orthologs of yeast proteins involved in protein trafficking. Overexpression of myc‐tagged SNX15 in COS‐7 cells altered the morphology of several endosomal compartments. In transient transfection experiments, myc‐SNX15 was first seen in small punctate spots and small ring structures. Later, myc‐SNX15 was found in larger rings. Finally, myc‐SNX15 was observed in large, amorphous membrane‐limited structures. These structures contained proteins from lysosomes, late endosomes, early endosomes, and the trans‐Golgi network. However, the morphology of the endoplasmic reticulum and Golgi was not affected by overexpression of myc‐SNX15. In myc‐SNX15‐overexpressing cells, the endocytosis of transferrin was severely inhibited and endocytosis of tac‐trans‐Golgi network (TGN) 38 and tac‐furin was slowed. In addition, the recycling of internalized tac‐TGN38 and tac‐furin was also inhibited. Both the morphological and biochemical data indicate that SNX15 plays a crucial role in trafficking through the endocytic pathway. This is the first demonstration that a mammalian SNX protein is involved in protein trafficking.
Prominin: A Story of Cholesterol, Plasma Membrane Protrusions and Human Pathology
Authors: Corbeil Denis , Röper Katja , Fargeas Christine A. , Joester Angret , Huttner Wieland B.
Published: March 2003

Prominin is the first identified member of a novel family of polytopic membrane proteins conserved throughout the animal kingdom. It has an unusual membrane topology, containing five transmembrane domains and two large glycosylated extracellular loops. In mammals, prominin is expressed in various embryonic and adult epithelial cells, as well as in nonepithelial cells, such as hematopoietic stem cells. At the subcellular level, prominin is selectively localized in microvilli and other plasma membrane protrusions, irrespective of cell type. At the molecular level, prominin specifically interacts with membrane cholesterol and is a marker of a novel type of cholesterol‐based lipid ‘raft’. A frameshift mutation in the human prominin gene, which results in a truncated protein that is no longer transported to the cell surface, is associated with retinal degeneration. Given that prominin is concentrated in the plasma membrane evaginations at the base of the outer segment of rod photoreceptor cells, which are essential precursor structures in the biogenesis of photoreceptive disks, it is proposed that prominin has a role in the generation of plasma membrane protrusions, their lipid composition and organization and their membrane‐to‐membrane interactions.
Sorting and Transport of Alpha Herpesviruses in Axons
Authors: Tomishima M. J. , Smith G. A. , Enquist L. W.
Published: March 2003

The alpha herpesviruses, a subfamily of the herpesviruses, are neurotropic pathogens found associated with most mammalian species. The prototypic member of this subfamily is herpes simplex virus type 1, the causative agent of recurrent cold sores in humans. The mild nature of this disease is a testament to the complex and highly regulated life cycle of the alpha herpesviruses. The cellular mechanisms used by these viruses to disseminate infection in the nervous system are beginning to be understood. Here, we overview the life cycle of alpha herpesviruses with an emphasis on assembly and transport of viral particles in neurons.
Dynamics of Leptomycin B‐Sensitive Nucleocytoplasmic Flux of Parathyroid Hormone‐Related Protein
Authors: Lam Mark H. C. , Henderson Beric , Gillespie Matthew T. , Jans David A.
Published: March 2003

Parathyroid hormone‐related protein is responsible for hypercalcemia induced by various tumors. The similarity of its N‐terminus to that of parathyroid hormone enables parathyroid hormone‐related protein to share parathyroid hormone's signaling properties, but the rest of the molecule possesses distinct functions including a role in the nucleus/nucleolus in reducing apoptosis and enhancing cell proliferation. We have previously shown that parathyroid hormone‐related protein nuclear import is mediated by importin β1. Here we use fluorescence recovery after photobleaching for the first time to show that, in living cells, parathyroid hormone‐related protein is exported from the nucleus in a leptomycin B‐sensitive manner, implicating CRM1 as the parathyroid hormone‐related protein nuclear export receptor. Leptomycin B treatment significantly reduced the rate of nuclear export 4 −10‐fold, thereby increasing parathyroid hormone‐related protein concentration in the nucleus/nucleolus about 2‐fold. Intriguingly, this also led to a 2‐fold reduced nuclear import rate. Inhibiting the nuclear export of a protein able to shuttle between nucleus and cytoplasm through distinct receptors thus can also affect nuclear import, indicating that the subcellular localization of a protein containing distinct nuclear import and export signals is the product of an integrated system. Although there have been several recent studies examining the dynamics of intranuclear transport using fluorescence recovery after photobleaching, this represents, to our knowledge, the first use of the technique to examine the kinetics of nucleocytoplasmic flux in living cells.
Kinetic Timing: A Novel Mechanism That Improves the Accuracy of GTPase Timers in Endosome Fusion and Other Biological Processes
Authors: Li Guangpu , Qian Hong
Published: March 2003

The GTPase superfamily contains a large number of proteins that function as molecular switches by binding and hydrolyzing GTP molecules. They are localized at various intracellular organelles and control diverse cellular processes. For many GTPases, the lifetime of the activated, GTP‐bound state is believed to serve as a timer in determining the activation time of a biological event such as membrane fusion and signal transduction. However, such a timer is intrinsically stochastic due to thermal noise at the level of single GTPase molecules. Here, we describe a mathematical model that shows how a directional GTPase cycle, in a nonequilibrium steady‐state driven by GTP hydrolysis, can significantly reduce the variance in the lifetime of an activated GTPase molecule and thereby increase the accuracy and efficiency of the timer. This mechanism, termed kinetic timing, articulates a clear function for the energy consumption in GTPase‐controlled biological processes. It provides a rationale for why biological timers utilize a GTP hydrolysis cycle rather than a simple GTP binding–dissociation equilibrium, and why the GTP‐bound state is a better timer than the GDP‐bound state. It also explains the necessity for the existence of multiple GTP‐bound intermediates identified by fluorescence spectroscopy and nuclear magnetic resonance studies.
Characterization of Novel Rab6‐Interacting Proteins Involved in Endosome‐to‐TGN Transport
Authors: Monier Solange , Jollivet Florence , Janoueix‐Lerosey Isabelle , Johannes Ludger , Goud Bruno
Published: March 2003

Rab6 GTPase regulates intracellular transport at the level of the Golgi complex. Using the yeast two‐hybrid screen, we have isolated two clones that specifically interact with the three isoforms of Rab6 present in mammalian cells (Rab6A, A′ and B). The cDNAs encode two proteins of 976 and 1120 amino acids (calculated molecular mass of 112 and 128 kDa, respectively) that we named Rab6IP2A and Rab6IP2B (for Rab6 Interacting Protein 2). The two proteins likely correspond to spliced variants of the same gene. Rab6IP2s have no significant homology with other known proteins, including Rab effectors or partners. They are ubiquitously expressed, mostly cytosolic and found in high molecular mass complexes in brain cytosol. We show that Rab6IP2s can be recruited on Golgi membranes in a Rab6:GTP‐dependent manner. The overexpression of any form of Rab6IP2 has no detectable effect on the secretory pathway. In contrast, the retrograde transport of the Shiga toxin B subunit between the plasma membrane and the Golgi complex is partly inhibited in cells overexpressing the Rab6‐binding domain of Rab6IP2. Our data suggest that Rab6IP2s is involved in the pathway regulated by Rab6A′.
1st Class Ticket to Class I: Protein Toxins as Pathfinders for Antigen Presentation
Authors: Smith Daniel C. , Lord J. Michael , Roberts Lynne M. , Tartour Eric , Johannes Ludger
Published: March 2003

A number of bacterial toxins have evolved diverse strategies for crossing membrane barriers in order to reach their substrates in the mammalian cytosol. Recent studies show that this property can be exploited for the delivery of fused antigens into the major histocompatibility complex class I‐restricted presentation pathway, with the goal of eliciting a specific immune response. Here we discuss the peculiarities of the trafficking pathways of a variety of toxins, and how these may allow the toxins to be used as delivery vehicles for therapeutic and diagnostic purposes.
Lipid Rafts and Assembly of Enveloped Viruses
Authors: Suomalainen Maarit
Published: March 2003

The plasma membrane, late secretory pathway and endosomal compartments contain detergent‐insoluble raft microdomains that are enriched in sphingolipids and cholesterol. Rafts are currently an intensively studied topic of cell biology, and raft involvement has been implicated in numerous cellular processes. A number of recent reports have localized structural proteins of several enveloped viruses to rafts, thus raising the possibility that rafts also play a role in the assembly and budding of viruses, but what exactly that role might be is still unknown.
AP‐1A and AP‐3A Lysosomal Sorting Functions
Authors: Reusch Uwe , Bernhard Olaf , Koszinowski Ulrich , Schu Peter
Published: March 2003

Heterotetrameric adaptor‐protein complexes AP‐1A and AP‐3A mediate protein sorting in post‐Golgi vesicular transport. AP‐1A and AP‐3A have been localized to the trans‐Golgi network, indicating a function in protein sorting at this compartment. AP‐3A appears to mediate trans‐Golgi network‐to‐lysosome and also endosome‐to‐lysosome protein sorting. AP‐1A is thought to be required for both trans‐Golgi network‐to‐endosome transport and endosome‐to‐trans‐Golgi network transport. However, the recent discovery of a role for monomeric GGA (Golgi localized γ‐ear containing, ARF binding protein) adaptor proteins in trans‐Golgi network to endosome protein transport has brought into question the long‐discussed trans‐Golgi network‐to‐endosome sorting function of AP‐1A. Murine cytomegalovirus gp48 contains an unusual di‐leucine‐based lysosome sorting signal motif and mediates lysosomal sorting of gp48/major histocompatibility complex class I receptor complexes, preventing exposure of major histocompatibility complex class I at the plasma membrane. We analyzed lysosomal sorting of gp48/major histocompatibility complex class I receptor complexes in cell lines deficient for AP‐1A, AP‐3A and both, to determine their sorting functions. We find that AP1‐A and AP3‐A mediate distinct and sequential steps in the lysosomal sorting. Both sorting functions are required to prevent MHC class I exposure at the plasma membrane at steady‐state.
Molded bone augmentation by a combination of barrier membrane and recombinant human bone morphogenetic protein‐2
Authors: Takeishi H , Irie K , Okuda K , Ozawa H , Yajima T , Ejiri S
Published: March 2003

OBJECTIVES: To provide the histological background to a new method of local bone augmentation, we examined the events occurring beneath a barrier membrane applied with recombinant human bone morphogenetic protein‐2 (rhBMP‐2).

MATERIALS AND METHODS: The effects on bone augmentation of rhBMP‐2, applied with a membrane mold (BMP‐Memb), over surgically‐induced bone defects in rat calvaria were examined histologically, and the results compared with those from application of rhBMP‐2 (BMP) alone, or of a molded membrane (Memb) alone.

RESULTS: At postoperative week 2, the BMP group showed the most marked bone formation. However, the bone diminished in size by week 8. The Memb group showed slow but continuous bone formation by week 8. In the BMP‐Memb group, bone filled the space in the mold at week 2, and this was maintained until week 8. Moreover, the soft tissue that had intervened between newly formed bone and the membrane in the Memb group was not evident in the BMP‐Memb group, in which bone had formed directly on the membrane.

CONCLUSIONS: The results suggest that the combination of rhBMP‐2 and barrier membrane has advantages in producing and maintaining bone in the intended shape by inducing osteoblasts directly on the inner surface of the membrane.
Factors associated with the temporomandibular disorder, pain dysfunction syndrome (PDS): Manchester case–control study
Authors: Macfarlane TV , Gray RJM , Kincey J , Worthington HV
Published: March 2003

OBJECTIVES: To determine the individual and combined effects of potential risk factors in relation to the temporomandibular disorder, Pain Dysfunction Syndrome (PDS).

DESIGN: Case–control study.

MATERIAL AND METHODS: Cases were new referrals to the temporomandibular disorder clinic of the University Dental Hospital of Manchester, diagnosed with PDS. Controls were randomly selected from 24 dental practices. Using a postal questionnaire information was collected on socio‐demographic, local mechanical, psychological factors, co‐morbidities and illness behaviour. The adjusted participation rate was similar in cases and controls (64%), and 131 cases and 196 controls finally participated in the study.

RESULTS: Compared with the controls, the cases were more likely to report that their teeth felt as though they did not fit together properly [odds ratio (OR) 8, 95% Confidence Interval (CI) 6–13] and report history of facial trauma (OR 3, 95% CI 2–6). Both diurnal and nocturnal grinding were significantly associated with PDS, and individuals who reported grinding their teeth both during the day and at night had a risk of 6; 95% CI 3–13 for PDS compared with those who did not. A history of orthodontic treatment, having any dentures, having missing teeth, use of chewing gum or biting the fingernails did not show any relationship with PDS. People who took medication for the bowels had a higher risk of PDS (OR 2, 95% CI 1–4). Participants with frequent headaches had a threefold increase in risk of having PDS (OR 3, 95% CI 2–5) while having pain in parts of the body other than the head was associated with an OR of 3 (95% CI 2–5). An increased propensity to have PDS was seen in those individuals with higher levels of psychological distress (OR 3; 95% CI 1–4 in the highest category, test for trend P < 0.001) and sleep disturbance (OR 5; 95% CI 2–94 in the highest category, test for trend P < 0.001). Aspects of illness behaviour, such as disease conviction (OR 4; 95% CI 2–9 in the highest category) and perception of illness (0.3; 95% CI 0.2–0.5) were associated with PDS. The result for the denial scale became statistically significant after adjustment for age and gender (2; 95% CI 1–3).

CONCLUSIONS: The current case–control study provides complementary epidemiological information on oro‐facial pain (OFP) and supports a multifactorial aetiology of PDS, with factors from many domains, including local mechanical factors, psychological and co‐morbidities. People with PDS were characterized by frequent headaches, history of facial trauma, teeth grinding, sleep problems, pain elsewhere in the body and high levels of psychological distress. From the results of current study and available evidence it seems inappropriate to consider PDS in isolation and future research should adopt a multidisciplinary approach to OFP.
Oral fungal and bacterial infections in HIV‐infected individuals: an overview in Africa
Authors: Hodgson TA , Rachanis CC
Published: March 2003

Oral opportunistic infections developing secondary to human immunodeficiency virus (HIV) infection have been reported from the early days of the epidemic and have been classified by both the EC‐Clearinghouse and the World Health Organisation (WHO). Among the fungal infections, oral candidiasis, presenting in African HIV‐infected patients has been sporadically documented. We review the literature with respect to candidal carriage, oral candidiasis prevalence and the predictive value of oral candidiasis for a diagnosis of underlying HIV disease in African HIV‐infected patients. The use of oral candidiasis as a marker of disease progression, the species of yeasts isolated from the oral cavity in Africa and the resistance of the yeasts to antifungal agents and treatment regimens are discussed. Orofacial lesions as manifestations of the systemic mycoses are rarely seen in isolation and few cases are reported in the literature from Africa. In spite of the high incidence of noma, tuberculosis, chronic osteomyelitis and syphilis in Africa, surprisingly there have been very few reported cases of the oral manifestations of these diseases in HIV‐positive individuals. Orofacial disease in HIV‐infected patients is associated with marked morbidity, which is compounded by malnutrition. The authors indicate specific research areas, initially directed at the most effective management strategies, which would complete data in this important area.