bluuebunny/crossref_metadata_2025 huggingface dataset:
Antagonist muscle coactivation during isokinetic knee extension
Authors: Aagaard P. , Simonsen E. B. , Andersen J. L. , Magnusson S. P. , Bojsen‐Møller F. , Dyhre‐Poulsen P.
Published: March 2003

The aim of the present study was to quantify the amount of antagonist coactivation and the resultant moment of force generated by the hamstring muscles during maximal quadriceps contraction in slow isokinetic knee extension. The net joint moment at the knee joint and electromyographic (EMG) signals of the vastus medialis, vastus lateralis, rectus femoris muscles (quadriceps) and the biceps femoris caput longum and semitendinosus muscles (hamstrings) were obtained in 16 male subjects during maximal isokinetic knee joint extension (KinCom, ROM 90–10°, 30° · s−1). Two types of extension were performed: [1] maximal concentric quadriceps contractions and [2] maximal eccentric hamstring contractions. Hamstring antagonist EMG in [1] were converted into antagonist moment based on the EMG‐moment relationships determined in [2] and vice versa. Since antagonist muscle coactivation was present in both [1] and [2] a set of related equations was constructed to yield the moment/EMG relationships for the hamstring and quadriceps muscles, respectively. The equations were solved separately for every 0.05° knee joint angle in the 90–10° range of excursion (0°=full extension) ensuring that the specificity of muscle length and internal muscle lever arms were incorporated into the moment/EMG relationships established. Substantial hamstring coactivation was observed during quadriceps agonist contraction. This resulted in a constant level of antagonist hamstring moment of about 30 Nm throughout the range of motion. In the range of 30–10° from full knee extension this antagonist hamstring moment corresponded to 30–75% of the measured knee extensor moment. The level of antagonist coactivation was 3‐fold higher for the lateral (Bfcl) compared to medial (ST) hamstring muscles. The amount of EMG crosstalk between agonist–antagonist muscle pairs was negligible (RXY2<0.02–0.06). The present data show that substantial antagonist coactivation of the hamstring muscles may be present during slow isokinetic knee extension. In consequence substantial antagonist flexor moments are generated. The antagonist hamstring moments potentially counteract the anterior tibial shear and excessive internal tibial rotation induced by the contractile forces of the quadriceps near full knee extension. In doing so the hamstring coactivation is suggested to assist the mechanical and neurosensory functions of the anterior cruciate ligament (ACL).
Specific protein alteration in the soleus following immobilization‐atrophy
Authors: Wagatsuma A. , Yamada S.
Published: March 2003

To investigate the effect of immobilization in a shortened position on protein alteration in the mouse soleus, total protein from immobilized and control muscle were analyzed by SDS‐PAGE and two‐dimensional polyacrylamide gel electrophoresis. Five‐week‐old male ddY mice (n=22) were used throughout this study. A 67.3 kDa protein was significantly increased by 1.7‐fold in the immobilized muscles in SDS‐PAGE compared to control muscle (P<0.001). This protein had the same mobility as serum albumin. The isoelectric point of the 67.3 kDa protein was pH 6.3, similar to serum albumin (range from pH 6.0 to 6.3). Specific antibody to the 67.3 kDa protein reacted with serum albumin by Western blot analysis. This protein was localized in the interstitial space in the control muscle and accumulated in pathologic areas in the immobilized muscle. It was presumed that this protein was a serum albumin‐like protein.
Anterior knee pain 7 years after an anterior cruciate ligament reconstruction with a bone‐patellar tendon‐bone autograft
Authors: Järvelä T. , Kannus P. , Järvinen M.
Published: March 2003

In order to evaluate the occurrence and predicting factors of anterior knee pain in patients after an anterior cruciate ligament reconstruction with a bone‐patellar tendon‐bone autograft, a functional, clinical and radiographic evaluation was performed on 91 patients on average 7 years after the surgery. Also, the isokinetic muscle torque was measured. At 7 years, anterior knee pain, as classified by the International Knee Documentation Committee (IKDC), was absent in 40 patients, mild in 47 patients, and moderate in 4 patients. None was classified as suffering from severe anterior knee pain. In the logistic regression analysis of predicting factors (forward‐stepping), knee extension torque deficit of the operated limb was the only factor that showed significant association with anterior knee pain. The other objective measurements of the knee (flexion torque deficit, range of motion, stability evaluation, and radiographic evaluation of the knee) were not associated with anterior knee pain. Subjectively and not surprisingly, the patients without anterior knee pain were more often satisfied with the overall outcome than the patients with anterior knee pain. Also, the Lysholm and Marshall knee scores and the final outcome in the IKDC rating scale were significantly better in patients without than with anterior knee pain.
Bone morphogenetic proteins and tendon repair
Authors: Aspenberg P. , Forslund C.
Published: March 2003

Bone repair is controlled by signalling proteins as well as mechanical stimuli. Bone morphogenetic proteins (BMPs), implanted or injected into a fracture site, can enhance bone healing, and so can mechanical stimulation. Possibly, mechanical signals can alter BMP expression, but furthermore, tissue differentiation initiated by an implanted BMP could be guided into the required direction by mechanical signals. Mechanical stimulation also has profound effects on tendon repair. We studied the effects of 3 different BMPs in a rat tendon repair model. One of these, osteogenic protein 1 (OP‐1) induced bone formation in the tendon at the expense of mechanical strength and thus overrode any mechanical control system. On the other hand, cartilage derived morphogenetic protein 1 and 2 (CDMP‐1 and ‐2) both made the tendon callus bigger and stronger at an early time point.
A prospective four‐ to seven‐year follow‐up after arthroscopic anterior cruciate ligament reconstruction
Authors: Brandsson S. , Faxén E. , Kartus J. , Jerre R. , Eriksson B. I. , Karlsson J.
Published: March 2003

The aim of this study was to evaluate the results after arthroscopic anterior cruciate ligament reconstruction using a bone‐patellar tendon‐bone graft in 99 patients, who were followed up prospectively for four to seven years. The pre‐injury Tegner activity level was 7 compared with 5 at the four‐ to seven‐year follow‐up (P<0.0001). The preoperative Lysholm score was 74.5 points. At the two‐year follow‐up, the Lysholm score was 95 points, while it was 90 points at the four‐ to seven‐year follow‐up (P<0.0001 preoperative vs two years and preoperative vs four to seven years and P<0.0005 two years vs four to seven years). Using the IKDC evaluation system, 80% of the patients were classified as normal or nearly normal and 20% as abnormal or severely abnormal at the final follow‐up. The KT‐1000 laxity measurements revealed a side‐to‐side difference of 2.9 mm preoperatively, 0.6 at two years and 1.0 mm at four to seven years. Twenty‐six patients underwent additional surgery during the follow‐up period. The results after arthroscopic reconstruction of the anterior cruciate ligament appear to be satisfactory both at the short‐ and the medium‐term follow‐ups, but there appears to be some deterioration between the two‐year and the four‐ to seven‐year follow‐up.
Creatine supplementation improves sprint performance in male sprinters
Authors: Skare O.‐C. , Skadberg Ø. , Wisnes A. R.
Published: March 2003

The object of this study was to evaluate the effect of creatine (Cr) supplementation in well trained male sprinters. The study was performed as a single blind test on 18 sprinters at a local competition level. During the last two years a substantial part of their training had consisted of a series of maximal sprints with short rest periods to improve their fatigue resistance. The participants consumed either 20 g Cr+20 g glucose per day (Cr group, n=9) or 40 g glucose per day (placebo group, n=9), divided into 4 equal dosages. The effect of Cr on sprint performance was evaluated in two tests, 1×100 m sprint and an intermittent 6×60 m sprint. Cr supplementation increased the 100 m sprint velocity (11.68±0.27 s vs 11.59±0.31 s) and reduced the total time of 6 intermittent 60 m sprints (45.63±1.11 s vs 45.12±1.1 s), whereas no changes were observed in the placebo group. The sprint velocity was significantly increased in 5 out of 6 intermittent 60 m sprints. Venous blood was drawn 5 min after finishing the final intermittent 60 m run. Plasma lactate, Cr and serum creatinine (Crn) were all increased in the Cr group compared to presupplementation values; no changes were observed in the placebo group. The improved sprint performance suggests an increased availability of energy substrate for performing work, possibly as a result of increased skeletal muscle creatine phosphate (PCr).
Prevalence of knee instability in relation to sports activity
Authors: Hahn T. , Foldspang A. , Ingemann‐Hansen T.
Published: March 2003

The objective was to estimate the prevalence of knee instability among active athletes and to investigate potential associations to type, amount and duration of sports participation. Based on a questionnaire, 339 athletes provided information about different features of occupation, sports activity and knee instability. The 12‐month period prevalence of knee instability and constant or recurrent knee instability, and absence from sport and absence from work due to knee instability, was 22%, 14%, 5% and 1%, respectively. Knee instability as such, and constant or recurrent knee instability were found to be positively associated with female gender and different features of occupational work. In conclusion, knee instability is a commonly reported phenomenon among active athletes. It was found to be independent of the type and the amount of sports activity but highly dependent on female gender, type and amount of occupational work.
A randomized controlled trial of rehabilitation after hospitalization in frail older women: effects on strength, balance and mobility
Authors: Timonen Leena , Rantanen Taina , Ryynänen Olli‐Pekka , Taimela Simo , Timonen Tero E. , Sulkava Raimo
Published: March 2003

When frail older people become acutely ill, they are at increased risk of further functional deterioration and rehabilitation is needed to restore functioning. The effects of an out‐patient multicomponent training program including strength training after hospitalization were studied in a randomized controlled trial. Sixty‐eight women (mean age 83.0 ± 3.9 years) who were hospitalized due to an acute illness and were mobility impaired at admission were randomized into training (N = 34) and home exercise (N = 34) groups. Maximal voluntary isometric strength of knee extension and hip abduction, dynamic balance, and maximal walking speed were measured before and after the 10‐week training period, and 3 and 9 months after the end of the intervention. After the intervention, significant improvements were observed in the training group compared to the home exercise group in the maximal voluntary isometric knee extension strength (20.8% vs. 5.1%,P= 0.009), balance scale (+ 4.4 points vs. −1.3 points,P= 0.001) and walking speed (+ 0.12 m s−1vs. −0.05 m s−1,P= 0.022). Effects on knee extension and hip abduction strength, balance and walking speed were observed 3 months later, and some effects on hip abduction strength (9.0% vs. −11.8%,P= 0.004) and mobility were still apparent even 9 months after the intervention.
Muscle fibre type adaptation in the elderly human muscle
Authors: Andersen Jesper L.
Published: March 2003

This short review discusses changes in the fibre type distribution, myosin heavy chain isoform composition and histological appearance of the very elderly human skeletal muscle. Point of origin of the discussion comes from data that we have obtained from muscle biopsies from the vastus lateralis muscle of a group of frail very elderly subjects (age: 88 ± 3 years, range 85–97). Myosin heavy chain composition of muscle homogenates and single fibres, fibre type distribution, fibre size and capillary density were examined and compared with muscle biopsies from the young vastus lateralis muscle. Histological preparations of the muscle biopsies from our elderly subjects showed extended “grouping” (Nygaard & Sanchez, Anat Rec 1992: 202: 451–459) of the fibre types as well as significant changes in the appearance and size of the individual muscle fibres. On average, the fibre type composition of our very elderly subjects do not seem to be different to what is observed in a corresponding young group when examined with ATPase histochemistry. Likewise, the MHC composition of the muscle homogenates is comparable to what is observed in young subjects. Nevertheless, a detailed examination of the MHC composition of single fibres from the old subjects revealed that the most prominent phenotype was fibres co‐expressing MHC I and MHC IIA. This is very different from what is observed in the young muscle. Detailed investigation of longitudinally cut fibres indicated that some fibres in the very old muscle, in contrast to the young muscle, switch fibre type along the length of the fibre or contain areas or nuclear domains in which the MHC expression is different from the remaining part of the fibre.
A novel in vivo model in guinea pigs for dry skin syndrome
Authors: Sagiv Assaf Eliezer , Ingber Arieh , Dikstein Shabtay
Published: March 2003

Background/aims: The lack of a suitable, validated animal model for the comparison of the pharmacological effectiveness of known and potential moisturizers in the treatment of “dry skin syndrome” led us to develop such an in vivo model.

Methods: “Dry skin syndrome” was induced in guinea pigs by daily application of 2% sodium lauryl sulphate (SLS) in deionized water on one of the two shaved flanks for three consecutive days. After ascertaining skin dryness, that side was treated with an agent for 6 days. The in vivo humectant effect was measured by a Corneometer CM 825®, erythema was measured by a Mexameter MX 16®. In some cases histological studies were carried out.

Results: The treatment with the 2% SLS led to a consistent “dry skin syndrome” for 2 weeks. Glycerol, Vaseline, urea and ammonium lactate treatments validated the model, since the Corneometer CM 825® readings of the treated dry side was equal to that of the control untreated side after 1 week of treatment. Mexameter MX 16® measurements showed abolishment of the erythema by glycerol only. Histological study showed that SLS treatment creates acanthosis that is partially reversed by Vaseline and fully reversed by glycerol treatment.

Conclusion: The guinea pig dry skin model is a relevant model of the human “dry skin syndrome”. The instrumental results combined with the histological findings indicate that erythema measurements are relevant for the determination of curative effect.
Use of Cutometer to assess epidermal hydration
Authors: Dobrev Hristo
Published: March 2003

Background/aims: The Cutometer equipped with a 2‐mm diameter suction probe is a device suitable for assessment of epidermal mechanics. The objectives of this study were to determine the sensitivity of Cutometer parameters to epidermal hydration, to evaluate the correlation between skin mechanical parameters and skin capacitance, and to study the role of pretension of the skin.

Methods: In the first study, skin capacitance (Corneometer) and 10 mechanical parameters were determined before and 60 min after application of five different moisturizers on the volar forearm. In the second study, measurements of epidermal mechanics were made without and with 0.1 s presuction of the skin, before and 120 min after application of petrolatum and glycerin.

Results: Hydration of the skin significantly increased the values of capacitance and all rheological parameters. Delayed distension (Uv) and viscoelastic‐to‐elastic ratio (Uv/Ue) were the most sensitive Cutometer parameters. Significant correlations between skin capacitance and mechanical parameters were not found. Pretension of the skin did not significantly influence the values of skin mechanical parameters.

Conclusions: The non‐invasive measurements of skin elasticity are appropriate for an objective and quantitative evaluation of the complex effect of different dermatological and cosmetic products on skin mechanics and hydration.
Digital dermoscopy analysis of atypical pigmented skin lesions: a stepwise logistic discriminant analysis approach
Authors: Rubegni P. , Cevenini G. , Burroni M. , Dell'Eva G. , Sbano P. , Cuccia A. , Andreassi L.
Published: March 2003

Background: Digital microscopy is a non‐invasive diagnostic technique enabling determination of characteristics that cannot be appreciated by direct observation. If correctly applied, this technique can be useful for the diagnosis of pigmented skin lesions.

Purpose: To evaluate the utility of digital microscopy for analysing atypical benign and malignant pigmented skin lesions exploiting digital numerical filtering and automatic measurements.

Methods: Forty‐eight parameters were identified as possible discriminating variables, and were grouped in four categories: geometries, colours, textures, and islands of colour. Statistical analysis was used to identify the variables with the highest discriminating power.

Results: The high quality of the digital image made it possible to observe diagnostic signs in pigmented skin lesion images, acquired by the present technique, in great detail. Specially designed filtering enhanced certain diagnostic patterns. Stepwise discriminant analysis selected only 10 variables (the means of these variables were higher in melanomas than in nevi).

Conclusions: The combined use of digital dermoscopy and stepwise logistic discriminant analysis made it possible to single out the best objective variables for distinguishing atypical nevi and early melanoma.
Surface free energy characterization of vernix caseosa. Potential role in waterproofing the newborn infant
Authors: Youssef Wael , Wickett R. Randall , Hoath Steven B.
Published: March 2003

Background/aims: Vernix caseosa is a proteolipid biofilm synthesized by the human fetus, which progressively covers the fetal skin surface during the last trimester of pregnancy. The exact physiological functions of vernix are unclear. Hypothetically, it serves a role in “waterproofing” the fetus during the critical period of epidermal barrier development before birth. Vernix may also play a role in adaptation of the fetal skin surface to the dry, cool extrauterine environment after birth. Given the strategic position of vernix on the fetal skin surface and the rapidly changing environment encountered by the skin at birth, we proposed that investigation of vernix surface characteristics would facilitate understanding its putative physiological roles.

Methods: In this paper, we focused on the determination of the surface free energy (SFE) of vernix caseosa. Different approaches were used to calculate the SFE of vernix from contact angle (θ) measurements between vernix and various liquids (benzyl alcohol, diiodomethane, glycerol, and water). The critical surface tension (CST) of vernix was calculated using Zisman plots. The dispersive and the polar components of vernix SFE were calculated using the Owens–Wendt geometric mean method. Vernix was contrasted with petrolatum, a commonly used skin protectant.

Results: CST of fresh vernix was 40.5 dyne/cm while that of petrolatum was 35.8 dyne/cm. Fresh vernix polar SFE was 1.5 dyne/cm while petrolatum had almost no polar SFE component (0.03 dyne/cm). For all liquids (except the nonpolar diiodomethane) there was a significant decrease in contact angle with time.

Conclusions: The CST and the total SFE values suggest that vernix has very low surface energy and is highly unwettable. These findings are significant insofar as the main component in vernix is water, which is highly energetic. Although vernix has a very high water content, the major part of its SFE is hydrophobic (dispersive). The limited interaction between vernix and hydrophilic liquids supports the hypothesis that vernix acts as a natural protectant cream to “waterproof” the fetus in utero while submerged in the amniotic fluid.
Visualization of cutaneous hemoglobin oxygenation and skin hydration using near‐infrared spectroscopic imaging
Authors: Attas Michael , Hewko Mark , Payette Jeri , Posthumus Trevor , Sowa Michael , Mantsch Henry
Published: March 2003

Background/aims: The visualization of skin hemodynamics and tissue water content has important implications in a number of areas of dermatology, plastic surgery, and clinical skin evaluation. The aim of this study was to develop instrumentation and techniques for infrared spectroscopic imaging, and to evaluate whether they can be used to make objective assessments of skin health, perhaps even before clinical signs are evident.

Methods: A liquid‐crystal tunable filter was mounted on the front of the objective lens of an infrared‐sensitive charge‐coupled device digital camera. Sets of narrow‐band images of skin were acquired in vivo at wavelength intervals of 10 nm from 650 to 1050 nm, under computer control. The data processing techniques used to extract interpretable clinical information from the raw image sets included normalization, ratios, and multivariate analysis.

Results: To highlight the capabilities of these techniques, results are presented of two studies that generated spectroscopic images. One examined a volunteer’s forearm subjected to short interruptions of blood flow, and the other followed changes in a skin flap elevated on a rat model. The data sets were processed in different ways to determine several skin and blood parameters, in particular hemoglobin oxygen saturation, blood volume, and skin hydration. Variations in these parameters were followed non‐invasively as a function of time and location to study the skin’s response to blood flow changes, and to predict the viability of the skin.

Conclusion: Near‐infrared reflectance spectroscopic imaging is demonstrated to be a powerful augmentation to the standard clinical assessment of skin.
Water, salts and skin barrier of normal skin
Authors: Yoshizawa Yusuke , Kitamura Keijiro , Kawana Seiji , Maibach Howard I.
Published: March 2003

Background: We recently reported that open application of seawater for 20 min ameliorated experimental irritant contact dermatitis induced by sodium lauryl sulphate (SLS) cumulative irritation. The efficacy was overall contributed by 500 mm of sodium chloride (NaCI) and 10 mm of potassium chloride (KCl), which are consistent with the each concentration in seawater. Although the usefulness of mineral water with 500 mm NaCl and 10 mm KCl to treat atopic dermatitis (AD) or irritated skin was considered, seawater or its components would induce a feel of stinging in patients with AD. Furthermore, 20 min application was thought to be too long to use everyday as a treatment.

Objective: We report the effects of 3 types of mineral water with NaCl and KCl to check the further efficacy with lesser stinging by 2 min application.

Results: A mineral water with 250 mm NaCl and 50 mm KCl was the most effective water to prevent disruption of skin barrier and stratum corneum water content after cumulating irritation by SLS. Moreover, improvement of skin dryness and pruritus were shown 2 weeks after the application of the mineral water to a 6‐year‐old boy with atopic dermatitis.

Conclusion: Our results suggested the possible usefulness of the mineral water with 250 mm NaCl and 50 mm KCl as the therapy of atopic dermatitis of other chronic dermatitis. Although the mineral water would not cure those skin diseases, it could be an adjunctive therapy. Further controlled clinical trials with evaluation by TEWL and capacitance are required to declare the efficacy of the mineral water in the treatment of patients with AD or other chronic dermatitis.
The use of different concentrations of betaine as a reducing irritation agent in soaps monitored visually and non‐invasively
Authors: Nicander Ingrid , Åberg Peter , Ollmar Stig
Published: March 2003

Background/aims: Products containing detergents can damage the skin and give rise to irritant contact dermatitis. Therefore, attempts have been made to find less irritating detergents as well as substances decreasing undesired side‐effects of detergents, and a novel approach is offered by betaine. The aim of the study has been to determine the irritating properties of some liquid soaps for personal hygiene and to map the effect of different concentrations of betaine using electrical impedance, trans‐epidermal water loss and visual inspection.

Methods: Twenty‐eight healthy subjects were patch tested with different commercial soaps with and without betaine and sodium lauryl sulphate on both volar forearms for 24 h. A site with distilled water and an unoccluded area were used as references. Responses of the skin reactions were evaluated by visual inspection and by measuring trans‐epidermal water loss and electrical impedance before application and 24 h after removal of the chambers.

Results/conclusions: Significant skin reactions were found for all soaps tested but the soaps containing betaine were the least irritating. However, the skin irritation did not decrease with increasing concentrations of betaine in the tested range. On the whole the differences between the products were not large. The non‐invasive methods used were more sensitive than visual assessment for evaluation of invisible or barely visible skin responses.
Cell Invasion by Un‐Palatable Parasites
Authors: Sibley L. David , Andrews Norma W.
Published: March 2003

While some intracellular pathogens invade and replicate exclusively in phagocytic host cells, others have evolved mechanisms to stimulate their uptake by cells not equipped with well‐developed phagocytic machinery. A common mechanism utilized by bacteria involves the induction of macropinocytosis, or of other F‐actin‐driven processes which result in engulfment of the pathogen through formation of a plasma membrane‐derived vacuole. Interestingly, this type of ‘induced phagocytosis’ mechanism does not appear to be utilized by protozoan parasites, which are significantly larger than bacteria in size (about 5–10 μm in average length). Intracellular protozoa either restrict themselves to infecting ‘professional’ phagocytes (one example is the trypanosomatid Leishmania), or utilize highly unusual mechanisms for gaining access to the intracellular environment. Here we discuss what has been revealed in recent years about the remarkable cell invasion strategies of two highly successful intracellular parasites: Toxoplasma gondii and Trypanosoma cruzi. Toxoplasma utilizes a distinct form of actin/myosin‐dependent gliding motility to propel itself into mammalian cells, while T. cruzi invades by subverting a Ca2+‐regulated lysosomal exocytic pathway.
Actin Assembly Plays a Variable, but not Obligatory Role in Receptor‐Mediated Endocytosis
Authors: Fujimoto L. Miya , Roth Robyn , Heuser John E. , Schmid Sandra L.
Published: March 2003

Three cell‐permeant compounds, cytochalasin D, latrunculin A and jasplakinolide, which perturb intracellular actin dynamics by distinct mechanisms, were used to probe the role of filamentous actin and actin assembly in clathrin‐mediated endocytosis in mammalian cells. These compounds had variable effects on receptor‐mediated endocytosis of transferrin that depended on both the cell line and the experimental protocol employed. Endocytosis in A431 cells assayed in suspension was inhibited by latrunculin A and jasplakinolide, but resistant to cytochalasin D, whereas neither compound inhibited endocytosis in adherent A431 cells. In contrast, endocytosis in adherent CHO cells was more sensitive to disruption of the actin cytoskeleton than endocytosis in CHO cells grown or assayed in suspension. Endocytosis in other cell types, including nonadherent K562 human erythroleukemic cells or adherent Cos‐7 cells was unaffected by disruption of the actin cytoskeleton. While it remains possible that actin filaments can play an accessory role in receptor‐mediated endocytosis, these discordant results indicate that actin assembly does not play an obligatory role in endocytic coated vesicle formation in cultured mammalian cells.
Caveolins and Cellular Cholesterol Balance
Authors: Ikonen Elina , Parton Robert G.
Published: March 2003

Caveolins are major integral membrane components of caveolae. Over the last few years, evidence has accumulated for a close link between caveolin, caveolae, and the regulation of cellular cholesterol levels. However, the exact role of caveolin in this process, the intracellular trafficking routes followed by caveolin/cholesterol complexes, and the relationship of caveolin‐cholesterol to other caveolin‐mediated processes such as signal transduction have remained unclear. Recent findings from a number of systems suggest that specific signaling pathways require precise regulation of cellular cholesterol. Here we review evidence for caveolin regulation of cholesterol transport and consider how this may relate to signal transduction.
A Screen of Random Sequences for those that Alter the Trafficking of the Influenza Virus Hemagglutinin In Vivo
Authors: Lewis Cheryl M. , Latham Katrina , Roth Michael G.
Published: March 2003

In order to determine if the sequence patterns known to specify internalization represent the majority of possible internalization signals, we identified random sequences capable of causing a reporter protein to be internalized at least several‐fold faster than the rate of non‐selective internalization of membrane by clathrin‐coated pits. A library of influenza hemagglutinin (HA) proteins, bearing short random sequences in place of the wild‐type cytoplasmic domain, was prepared in recombinant SV40 virus. The library was expressed and screened for HAs that could internalize anti‐HA antibody from the medium. The cytoplasmic sequences of the selected proteins were determined. From a small sample of sequences, we detected several that did not resemble those previously identified. The known internalization signals must represent only a subset of the sequences that can serve as internalization signals.
The Protein Import Machinery of the Mitochondrial Membranes
Authors: Rassow Joachim , Pfanner Nikolaus
Published: March 2003

Mitochondria are surrounded by two membranes that contain independent and non‐related protein transport machineries. Remarkable progress was recently achieved in elucidating the structure of the outer membrane import channel and in the identification of new components involved in protein traffic across the intermembrane space and the inner membrane. Traditional concepts of protein targeting and sorting had to be revised. Here we briefly summarize the data on the mitochondrial protein import system with particular emphasis on new developments and perspectives.
Molecular Structures of Proteins Involved in Vesicle Fusion
Authors: Ybe Joel A. , Wakeham Diane E. , Brodsky Frances M. , Hwang Peter K.
Published: March 2003

We present a summary of the structures of 13 proteins involved in the docking and fusion of intracellular transport vesicles to their target membranes.
The Making and Breaking of the Endoplasmic Reticulum
Authors: Powell Kendall S. , Latterich Martin
Published: March 2003

The endoplasmic reticulum (ER) is a dynamic organelle central to many essential cellular functions. It is an important calcium store, which functions in cellular signal transduction cascades. It is also the site of entry for secreted proteins into the secretory pathway. Lumenal enzymes will fold and glycosylate these proteins, and if a protein is destined to be secreted, it will be packaged into membrane vesicles that bud off from the ER. The ER is also the site where most cellular lipids are synthesized. It is contiguous with the nuclear envelope, which serves as a diffusion barrier to control entry into and out of the nucleus. In the life cycle of a cell, the ER is in a constant flux of membrane traffic. What maintains the ER in the shape of an intact reticulum among this constant flux of material? We discuss the mechanisms that contribute to the biogenesis of the ER, the maintenance of the organelle, as well as processes that give the ER its characteristic shape and pattern of inheritance.
Proteomic Tools for Cell Biology
Authors: McDonald W. Hayes , Yates III John R.
Published: March 2003

Acquisition of large bodies of genomic sequence is facilitating the use of global techniques to assay cellular function. DNA microarrays have enabled the measurement of global mRNA levels and are able to detect changes in gene expression between different cellular states. Since much of the regulation of physiolgical processes happens post‐translationally, measuring only the mRNA levels gives an incomplete picture. Strategies to assay global expression, localization, or interaction of proteins fall into the emerging field of proteomics, with various combinations of techniques being utilized to separate and identify proteins. In this review, we will present a general overview of the currently available proteomic tools and then give examples of how these tools are being utilized to answer questions in cell biology.
Cholesterol is Required for the Formation of Regulated and Constitutive Secretory Vesicles from the trans‐Golgi Network
Authors: Wang Yanzhuang , Thiele1 Christoph , Huttner Wieland B.
Published: March 2003

We studied the role of cholesterol in regulated protein secretion in neuroendocrine cells by manipulating the cholesterol content of AtT‐20 cells. Depletion of cellular cholesterol levels caused a reversible block of immature secretory granule biogenesis at the level of the trans‐Golgi‐network, whereas increased cholesterol levels promoted immature secretory granule formation. Cholesterol depletion also blocked the formation of constitutive secretory vesicles, but did not inhibit the transport between the endoplasmic reticulum and the Golgi complex. Our results indicate that the assembly of cholesterol‐based lipid microdomains is required for the biogenesis of both regulated and constitutive secretory vesicles from the trans‐Golgi‐network in neuroendocrine cells.
The Roles of Claudin Superfamily Proteins in Paracellular Transport
Authors: Heiskala Marja , Peterson Per A. , Yang Young
Published: March 2003

The claudin superfamily consists of at least 18 homologous proteins in humans. These proteins are important structural and functional components of tight junctions in paracellular transport. Complexed with two other integral transmembrane proteins, occludin and junctional adhesion molecule, claudins are located in both epithelial and endothelial cells in all tight junction‐bearing tissues. Claudins interact directly with tight junction‐specific, membrane‐associated guanylate kinase homologues, ZO‐1, ZO‐2, and ZO‐3, and indirectly with AF‐6 and the myosin‐binding molecule cingulin. These protein–protein interactions promote scaffolding of the tight junction transmembrane proteins and provide a link to the actin cytoskeleton for transducing regulatory signals to and from tight junctions. The distinct permeability properties observed in different epithelia and endothelia seemingly result from the restricted tissue expression, variability of the homopolymer and heteropolymer assembly, regulated transcription and translation, and the subcellular localization of claudin family proteins. Defects in claudins are causatively associated with a variety of human diseases, demonstrating that claudins play important roles in human physiology. In conditions where the cell adhesion function contributed by tight junctions is essential, such as in altered paracellular transport, in proliferative diseases, and during morphogenesis, the claudin superfamily of homologous proteins provides the molecular basis for the uniqueness of tight junctions and emerges as a new target for intervention.
Morphogen Gradient Formation and Vesicular Trafficking
Authors: Entchev Eugeni V. , González‐Gaitán Marcos A.
Published: March 2003

Morphogens are secreted signaling molecules which form spatial concentration gradients while moving away from a restricted source of production. A simple model of gradient formation postulates that the morphogens dilute as they diffuse between cells. In this review we discuss recent data supporting the idea that movement of the morphogen could also occur via vesicular trafficking through the cells. We explore the implications of these results for the control of gradient formation and the determination of the gradient slope which ultimately encodes the coordinates of positional information.
Trafficking of the Salmonella Vacuole in Macrophages
Authors: Holden David W.
Published: March 2003

Salmonella enterica is a facultative intracellular pathogen which can replicate in macrophages. Intracellular Salmonella exist in a membrane‐bound compartment called the Salmonella‐containing vacuole. Most studies on Salmonella trafficking in relation to the endocytic pathway have concluded that the majority of Salmonella‐containing vacuoles do not interact extensively with late endosomes and lysosomes. Numerous bacterial genes have been identified which are required for survival and replication in macrophages. These include the spv operon, located on the large virulence plasmid, the phoP‐phoQ regulon, and those connected with the Salmonella pathogenicity island 2 type III secretion system. The functions of some of these genes are beginning to be understood. In this review, I discuss their roles in relation to our broader understanding of Salmonella trafficking in macrophages.
Myosin‐V, a Versatile Motor for Short‐Range Vesicle Transport
Authors: Langford George M.
Published: March 2003

Myosin‐V is a versatile motor involved in short‐range transport of vesicles in the actin‐rich cortex of the cell. It binds to several different kinds of vesicles, and the mechanism by which it interacts with the vesicle surface is being unraveled, primarily in melanocytes. Members of the Rab family of G‐proteins are required for the recruitment of myosin‐V to vesicles. Rab27a and its rabphilin‐like effector protein, Melanophilin, recruit myosin‐Va to melanosomes and appear to serve as the membrane receptor. Myosin‐V is also involved in fast axonal/dendritic transport and, interestingly, it forms a complex with kinesin, a microtubule‐based motor. This kinesin/myosin‐V heteromotor complex allows long‐range movement of vesicles within axons and dendrites on microtubules and short‐range movement in the dendritic spines and axon terminals on actin filaments. The direct interaction of motors from both filament systems may represent the mechanism by which the transition of vesicles from microtubules to actin filaments is regulated.
Short‐term exposure to alcohol increases the permeability of human oral mucosa
Authors: Howie NM , Trigkas TK , Cruchley AT , Wertz PW , Squier CA , Williams DM
Published: March 2003

OBJECTIVES: The aim of this study was to evaluate the effect of short‐term exposure to ethanol on the permeability barrier properties of human oral mucosa.

MATERIALS AND METHODS: Permeability constants (Kp× 10−4 cm min−1) to tritiated water were determined, for untreated human ventral tongue, and following treatment with phosphate‐buffered saline (PBS), 5, 15 or 40% ethanol using an in vitro perfusion chamber system. Some samples were also exposed to fluorescent‐labelled albumin and examined by fluorescence microscopy. Permeability barrier lipid composition was assessed in treated and untreated mucosa by heat separation, solvent extraction and thin layer chromatography.

RESULTS: Fifteen per cent ethanol significantly increased mucosal permeability (5.8 ± 0.44; P < 0.05) compared with untreated, PBS and 5% ethanol treated mucosa (4.69 ± 0.26, 4.48 ± 0.3 and 4.13 ± 0.27, respectively). Albumin was restricted to the epithelial surface in control tissue, but extended further through the epithelium and, in some cases, into the connective tissue after treatment with ethanol. Biochemical analysis revealed no significant difference in the epithelial lipid composition of treated and untreated mucosa.

CONCLUSIONS: These results suggest that short‐term exposure to ethanol may act as a permeability enhancer, possibly by causing molecular rearrangement of the permeability barrier, not as a result of lipid extraction.
Opportunistic infections associated with HIV infection in Africa
Authors: Maartens G
Published: March 2003

HIV‐associated infections in sub‐Saharan Africa differ markedly in their incidence from those in industrialized countries. Tuberculosis is the commonest cause of morbidity and mortality. Enteric pathogens such as microsporidiosis commonly cause disease as access to safe water is limited. Pneumocystis carinii pneumonia, which is the commonest opportunistic infection in industrialized countries, is uncommon in adults with HIV infection. This remains unexplained because P. carinii pneumonia is common in Black African HIV‐infected children. Cytomegalovirus and Mycobacterium avium complex, which only occur in severely immune‐suppressed individuals, are seldom found. One reason may be that survival after conversion to AIDS is relatively short in Africa. Patients often die before they develop severe immune suppression. Recently, prophylactic cotrimoxazole treatment was shown to be effective in symptomatic HIV‐infected adults in Africa. Tuberculosis preventive therapy is also effective in Africa, at least in the medium term. It is hoped that these two affordable interventions will become available to large numbers of patients identified in voluntary counselling and testing centres.
Prognostic significance of HIV‐associated oral lesions and their relation to therapy
Authors: Birnbaum W , Hodgson TA , Reichart PA , Sherson W , Nittayannanta SW , Axell TE
Published: March 2003

The oral manifestations of HIV infection have been considered to be of value in assessing disease progression in the developed world. However, the potential use of oral lesions as prognostic markers in resource‐poor countries has yet to be fully investigated. There is reasonably compelling evidence in the developed world for an association between oral lesions and viral load. However, the true nature of this association is less clear and there are few data available from the developing world. With the introduction of HAART, a change in prevalence of the oral manifestations of HIV infection has been observed, including regression of oral candidiasis, Kaposi's sarcoma and oral hairy leukoplakia. However, oral condylomata and herpes simplex virus infection appear to persist with HMRT therapy. Further research in partnership with resource‐poor countries is required to document disease progression and the associated oral lesions in both adults and children.
Enhancement of transmucosal permeation of cyclosporine by benzalkonium chloride
Authors: Van Der Bijl P , Van Eyk AD , Gareis AA , Thompson IOC
Published: March 2003

OBJECTIVES: Permeation of cyclosporin A (CsA) through intact and de‐epithelialized human vaginal mucosa in the presence and absence of benzalkonium chloride (BZCl) was tested.

MATERIALS AND METHODS: Human vaginal mucosa (snap‐frozen in liquid nitrogen, stored at −85°C) had been used for permeability experiments. CsA permeation through thawed frozen intact and de‐epithelialized vaginal mucosa was determined using a flow‐through diffusion apparatus (20°C, 24 h). Flux rates for CsA across these two mucosae were determined in the presence and absence of 0.01% BZCl. ANOVA and Duncan's multiple range test were used to test for steady‐state and an unpaired t‐test with Welch's correction was used to test for differences between the mean flux values at each time point (significance level of 5%). A piece of thawed tissue from each patient, before and after de‐epithelialization, was placed in formalin and histologically examined.

RESULTS: Flux rates of CsA across intact vaginal mucosa tended to increase by 28–46% in the presence of 0.01% BZCl, and CsA across de‐epithelialized mucosa by approximately 28%. The latter differences were statistically significantly higher after 10 h. Flux rates across de‐epithelialized mucosa were 52–140% higher in the presence of 0.01% BZCl (statistically significantly higher after 12 h).

CONCLUSIONS: The permeation of CsA through intact and de‐epithelialized human vaginal mucosa can be enhanced by 0.01% BZCl.
Oral signs and symptoms in relation to disease activity and site of involvement in patients with inflammatory bowel disease
Authors: Katz J , Shenkman A , Stavropoulos F , Melzer E
Published: March 2003

OBJECTIVE: An assessment of oral symptoms and signs in patients with inflammatory bowel disease (IBD).

METHODS: Fifty‐four patients with IBD, 34 with Crohn's disease (CD) and 20 with ulcerative colitis (UC) participated in the study. Forty‐two patients without gastrointestinal disease or complaints attending the orthopedic clinic served as controls. Each patient completed a written questionnaire and was subjected to an oral examination.

RESULTS: The main findings of this study were the higher prevalence of halitosis (50%vs 10%P < 0.0008), nausea (30%vs 7%, P < 0.017) and reflux (regurgitation) (45%vs 17%, P < 0.017) in patients with UC, and nausea (50%vs 7%, P < 0.026), dry mouth and halitosis (29%vs 10%, P < 0.026) and vomiting (41%vs 5%, P = 0.01) in patients with CD, compared with controls. Patients with active CD had a higher prevalence of dry mouth, nausea and vomiting compared with controls (46, 69 and 54%vs 10, 7 and 5%, respectively, P < 0.001) and of reflux compared with non‐active CD (46%vs 5%, P < 0.001). Patients with active UC had a higher prevalence of halitosis and regurgitation (50 and 60%vs 10 and 17%, P < 0.001) compared with controls.

CONCLUSIONS: The present study demonstrates increased frequency of oral signs and symptoms in patients with IBD. Patients with active CD had more oral signs compared with non‐active CD patients. Manifestations such as nausea, vomiting, regurgitation and dry mouth may have detrimental effects on teeth and soft tissues of the oral cavity. Communication between gastroenterologists and dentists is imperative for success of the overall treatment of their patients.
Saliva and inhibition of HIV‐1 infection: molecular mechanisms
Authors: Shugars DC , Sweet SP , Malamud D , Kazmi SH , Page‐Shafer K , Challacombe SJ
Published: March 2003

Oral fluids are rarely a vehicle for HIV‐1 infection in vivo, unlike other mucosal secretions. This unique property raises questions regarding (1) the molecular mechanisms responsible for the lack of salivary transmission, (2) the extent to which oral immunological responses mirror responses at other mucosal sites, (3) the use of promising salivary markers of HIV‐1 disease progression, (4) the relationship between oral and blood viral loads, (5) cofactors that influence oro‐genital transmission, and (6) the feasibility of oral‐based antibody testing for HIV‐1 diagnosis in the home. This paper discusses these questions and provides background summaries, findings from new studies, consensus opinions, practical relevance to developing countries, and suggestions for future research agenda on each of the key topics.