Ion channels and bacterial infection: the case of beta-barrel pore-forming protein toxins of Staphylococcus aureus

Staphylococcus aureus strains causing human pathologies produce several toxins, including a pore-forming protein family formed by the single-component alpha-hemolysin and the bicomponent leukocidins and gamma-hemolysins. The last comprise two protein elements, S and F, that co-operatively form the active toxin. alpha-Hemolysin is always expressed by S. aureus strains, whereas bicomponent leukotoxins are more specifically involved in a few diseases. X-ray crystallography of the alpha-hemolysin pore has shown it is a mushroom-shaped, hollow heptamer, almost entirely consisting of beta-structure. Monomeric F subunits have a very similar core structure, except for the transmembrane stem domain which has to refold during pore formation. Large deletions in this domain abolished activity, whereas shorter deletions sometimes improved it, possibly by removing some of the interactions stabilizing the folded structure. Even before stem extension is completed, the formation of an oligomeric pre-pore can trigger Ca(2+)-mediated activation of some white cells, initiating an inflammatory response. Within the bicomponent toxins, gamma-hemolysins define three proteins (HlgA, HlgB, HlgC) that can generate two toxins: HlgA+HlgB and HlgC+HlgB. Like alpha-hemolysin they form pores in planar bilayers with similar conductance, but opposite selectivity (cation instead of anion) for the presence of negative charges in the ion pathway. gamma-Hemolysin pores seem to be organized as alpha-hemolysin, but should contain an even number of each component, alternating in a 1:1 stoichiometry.

Can a post-operative brace in slight hyperextension prevent extension deficit after anterior cruciate ligament reconstruction? A prospective randomised study

It has been our observation that post-operative anterior cruciate ligament (ACL) braces together with the post-operative bandages do not always allow the knee to reach full extension. In ten uninjured knees with known hyperextension, the knees were bandaged in the same way as after an ACL-reconstruction. The knees were then studied radiologically in a Hypex brace set at 0 degrees, -5 degrees and -10 degrees of knee extension. Not a single knee was found to be straight in the brace set at 0 degrees. At -5 degrees most of the knees were straight or in slight hyperextension. It took -10 degrees to get all knees straight or in hyperextension. In a prospective randomised study 44 patients who underwent an arthroscopic ACL-reconstruction with a bone patellar tendon bone graft were randomised to use either a brace set at -5 degrees or a straight brace (0 degrees ) for at least the first three postoperative weeks. Before and three months after surgery range of motion was determined, using a goniometer with long arms, and sagittal knee laxity was measured with a KT-2000 arthrometer at manual max. Pre- and post-operative pain was evaluated with the Visual Analogue Scale (VAS). The same examiner (blindfolded to what type of brace was used) performed all the measurements. At three months, two of the 22 patients with the brace set at -5 degrees and twelve of the 22 patients with the straight brace had a loss of full extension of 2 degrees or more ( p<0.001). No significant differences were found between the groups in terms of knee flexion, sagittal knee laxity or post-operative pain. Although extension deficit after ACL-reconstruction can be prevented also in other ways, a Hypex brace set at -5 degrees seems to be an easy way of ensuring full knee extension.

The effect of dance training on joint mobility, muscle flexibility, speed and agility in young cross-country skiers--a prospective controlled intervention study

We evaluated a short-term (3 months) and a long-term (8 months) effect of dance training on joint mobility and muscle flexibility of the spine, hip and ankle and on speed and agility in young cross-country skiers. Twenty elite cross-country skiers - aged 12-15 years - participated in the study. Five males and five females received dance training (intervention group) and five males and five females did not dance (reference group). Joint mobility and muscle flexibility of the spine, hip and ankle joints were measured using a goniometer, a kyphometer, a measuring tape and a ruler. Two sports-related functional tests - the slalom-test and the hurdle-test - were also performed. These measurements/tests were performed before the start of the dancing period and after 3 and 8 months. The subjects from the intervention group increased their speed with 0.3 s after 3 (P = 0.05) and 8 months (P = 0.02), respectively, when measured with the slalom-test. They also improved their speed and agility according to the hurdle-test after 3 months with 0.8 s (P = 0.000) and 8 months with 0.6 s (P = 0.01). Furthermore, they increased flexion-extension of the thoracic spine with 7.5 degrees after 3 months (P = 0.05) and with 9 degrees degrees after 8 months (P = 0.03) and lateral flexion of the spine with 0.04 m (P = 0.005) and 0.03 m (P = 0.02) after 3 and 8 months, respectively. The reference group was impaired or unchanged in the studied parameters after both 3 and 8 months. We conclude that dance training has a positive effect on speed and agility and on joint mobility and muscle flexibility in flexion-extension and lateral flexion of the spine in young cross-country skiers.

The effect of exercise regimens on reflex response time of the vasti muscles in patients with anterior knee pain: a prospective randomized intervention study

The purpose of this prospective randomized intervention study was to evaluate the effect of two exercise protocols on reflex response time of vastus medialis obliquus (VMO), vastus lateralis (VL), in patients with anterior knee pain. Sixty patients were randomized into a 5-week treatment program, which consisted of only open kinetic chain tonification exercises (group I) (n = 30), or only closed kinetic chain tonification exercises (group II) (n = 30). Assessment of an aspect of neuromotor control was obtained by measuring the reflex response times of VMO and VL at the time of initial clinical examination, at the end of the exercise period (five weeks), and three months after the completion of the exercise period. At these evaluation occasions, the intensity and the number of times that the patients experienced anterior knee pain during daily life was recorded on a Visual Analog Scale (VAS). No alterations in reflex response times of VMO and VL were observed in either group. Changes of anterior knee pain over time were statistically significant in both groups. Only small and not statistically supported differences in anterior knee pain were found between the two groups. These results suggest that the reflex response times of the two vasti muscles can not be altered after a five week open or closed kinetic chain exercise program. In contrast, knee pain decreased significantly in both groups.

Dynamics and localization of activin A expression in rat gastric ulcers

BACKGROUND

Activin A, the homodimer of the activin/inhibin betaA subunit, has been shown to participate in cutaneous wound healing. In this study we intended to determine its part in gastric ulceration.

METHODS

Activin A expression was studied by immunohistochemistry and in situ hybridization in acetic-acid-induced chronic gastric ulcers in rat. The dynamics of this process were also assessed by quantitative real time RT-PCR and RNase protection assays (RPA). The effects of different doses of this cytokine on epithelial and mesenchymal cell proliferation were quantitated in vitro.

RESULTS

Low amounts of activin A and its mRNA were expressed by epithelia, endothelia and fibroblasts in intact gastric tissue. Granulation tissue of gastric ulcers and gastric glands adjacent to the ulcer rim expressed markedly increased amounts of activin protein as well as activin/inhibin betaA mRNA. RPA and RT-PCR studies revealed a more than 3-fold increase in the relative abundance of this mRNA. Activin A did not affect the proliferation rate of fibroblasts and epithelial cells in vitro.

CONCLUSIONS

Activin A participates in gastric ulcer healing in a similar fashion as in cutaneous wounding. Its expression on protein and mRNA level is markedly increased in ulcer base and rim.

The hazards of kissing when you are food allergic. A survey on the occurrence of kiss-induced allergic reactions among 1139 patients with self-reported food hypersensitivity

BACKGROUND

According to a few case reports, kissing can induce symptoms due to food allergy.

OBJECTIVE

We wanted to investigate the occurrence of kiss-induced allergic symptoms and other social inconveniences among patients with self-reported food hypersensitivity.

METHODS

A questionnaire was answered by 1139 patients (1-84 years old, mean age 29 years, 393 males and 746 females) who considered themselves to be food allergic.

RESULTS

12% of the patients experienced allergic symptoms when in close contact with (e.g., kissing) a person who had eaten a nontolerated food prior to the contact. Some case histories suggested that the symptoms only appeared if the food intake had occurred immediately before the kiss. In addition, the questionnaires showed that 55% had problems in daily life finding tolerable food, 44% were afraid of a severe reaction from eating nontolerated food, 13% could experience symptoms when sitting beside a person who was eating such a food, and 17% could experience symptoms in the kitchen when someone else was preparing such food.

CONCLUSIONS

What other people eat can influence the quality of life of food-allergic patients.

Pressure-induced phase transitions of piezoelectric single crystals from the langasite family: La3Nb0.5Ga5.5O14 and La3Ta0.5Ga5.5O14

The hydrostatic compression of piezoelectric single crystals of La(3)Nb(0.5)Ga(5.5)O(14) (LNG) and La(3)Ta(0.5)Ga(5.5)O(14) (LTG) was studied at pressures of up to 23 GPa in diamond-anvil high-pressure cells using single-crystal X-ray diffraction techniques. The reflection-intensity data for LNG and LTG were collected at pressures of up to 22.8 GPa and 16.7 GPa, respectively. Both compounds show anisotropic behaviour under pressure, which is caused by differences in bonding parallel to the a and c directions. The compression of strongly rigid structures leads to increasing internal strains and results, at pressures of 12.4 (3) GPa for LNG and 11.7 (3) GPa for LTG, in a transition to lower symmetry. The compressibilities along the c axis are almost the same for LNG and LTG through the whole investigated pressure range. In contrast, the pressure dependencies of the a axis of these materials are similar only for the initial phase, and the axial compressibilities for the high-pressure polymorphs of LNG and LTG are significantly different to each other. The volume compressibilities of trigonal LNG and LTG (space group P321) are about 0.007 GPa(-1); respective bulk moduli are 145 (3) GPa and 144 (2) GPa. The monoclinic high-pressure phases (space group A2) of LNG and LTG show differing compressions, which can be explained by the substitution of Ta(5+) for Nb(5+). Thus, the bulk moduli for the high-pressure polymorphs of LNG and LTG are B(0) = 93 (2) GPa and B(0) = 128 (12) GPa, respectively. The volume compressibilities of the high-pressure phases at 0.011 GPa(-1) for LNG and 0.008 GPa(-1) for LTG are higher than the initial phases, this effect being more pronounced in the case of LNG.

Self-release of ski-binding

We investigated whether twenty-five male and female downhill skiers of different ages (11 - 63 years) and skiing skills were able to self-release their ski binding by an inward twist of the foot and leg. We also studied possible correlations between thigh muscle torques and the ability to release the binding. All subjects used the same ski and binding, Marker Titanum M48, individually set according to weight, height, skiing skill, age, and boot sole length. Prior to the test we used a special torque wrench, the Vermont Release Calibrator, to verify that the settings of the binding corresponded to the appropriate torque (Nm) to produce a release. Isokinetic concentric and eccentric quadriceps and hamstring torques were measured. EMG was used to study which muscles are engaged in this self-test. Nineteen skiers were able to release the binding, while four children and the two muscularly weakest skiers were not. The medial hamstrings produced the highest degree of muscle activity during the inward twist release of the binding. There was a highly significant correlation between thigh muscle torques and the ability to release the binding.

The incidence of atopic dermatitis in school entrants is associated with individual life-style factors but not with local environmental factors in Hannover, Germany

BACKGROUND

Atopic dermatitis (AD) is a common skin disease in childhood. Micro- and macro-environmental factors have not yet been studied simultaneously in a large cohort of the same area in detail.

OBJECTIVES

The incidence of AD was investigated in 97% of all school entrants (n = 4219) in the city of Hannover, Germany, with regard to the influence of individual and environmental factors.

METHODS

A standardized questionnaire based on the criteria of Hanifin and Rajka that has the sensitivity and specificity of 97% compared with the clinical diagnosis of a dermatologist and a logistic regression model were used. Multiple local-based environmental factors were analysed for all 49 city quarters.

RESULTS

Of all children studied, 10.5% suffered from AD at some time in their lives. The frequency of AD was significantly increasing with more privileged socio-economic status (P < 0.01). Independent factors that were associated with a higher frequency of AD were German nationality (12.4% AD compared with 2.1% in non-German), higher paternal socio-economic status (i.e. father's profession), higher daily duration of the fathers' professional work and the lack of paternal shift work. In contrast, there was no significant association between the frequency of AD and local environmental factors such as the biological effective level of air pollution and urbanization.

CONCLUSIONS

In conclusion, we confirm an association between a privileged life-style and a higher incidence of AD in a large number of investigated children between 5 and 9 years of age (97.6% of children were 6 or 7 years old) for the German city of Hannover. We propose the socio-economic status as a marker for different life-styles and social micro-environments in further studies as there were multiple significant correlations between individual social and environmental factors. The macro-environment seems to be less important for the disease outcome in this context.

Anterior cruciate ligament injuries in young females playing soccer at senior levels

The aim of this investigation was to study the consequences of anterior cruciate ligament injuries in female soccer players. Special interest was focused on young female soccer players (< 16 years) sustaining anterior cruciate ligament injuries when playing at a senior level, which means playing together with players 19 years or older. In Sweden, all players belonging to an organized soccer club are insured by the same insurance company, the Folksam Insurance Company. Data of all soccer-related knee injuries in females reported to the Folksam Insurance Company between 1994 and 1998 were collected. A questionnaire was sent to 978 females who were registered to have sustained a knee injury before the age of 20 years. The response rate was 79%. Three hundred and ninety-eight female soccer players who had sustained an anterior cruciate ligament injury before the age of 19 years were analysed. Most of their anterior cruciate ligament injuries had been diagnosed using arthroscopy or magnetic resonance imaging (84%). Thirty-eight percent of the players had been injured before the age of 16 years. Of these, 39% were injured when playing in senior teams. When playing in senior teams 59% of the players below the age of 16 years and 44% of the players 16 years or older sustained their ACL injuries during contact situations. At the time of this investigation (2-7 years after the anterior cruciate ligament injury), altogether 78% (n = 311) reported that they had stopped playing soccer. The most common reason (80%) was symptoms from their anterior cruciate ligament-injured knee. It appears that many young female soccer players injure their anterior cruciate ligament when playing at a senior level. Therefore, we suggest that female soccer players under the age of 16 years should be allowed to participate only in practice sessions but not games at a senior level.

[Work-satisfaction and Health of Hospital Nursing and Medical Personnel]

The implementation of new service demands and increasing rationalisation measures exercise stress and pressure on medical and nursing personnel in German hospitals. However, their satisfaction and health are important quality criteria in the ranking of a hospital. Basing on the introduction of a new tool, an inquiry was conducted among the medical and nursing personnel of two hospitals (A and B) in respect of the quality of their working conditions. The scope of the questionnaires covered the nature and kind of the work, opportunities of professional success, management of co-operation and conflicts, physical and structural obstacles to smooth working as well as the management of quality. Finally, a scale of complaints and a burn-out scale served to assess the personnel's subjective health situation. The questionnaire was submitted in hospital A between November 1999 and February 2000 to a total of 39 doctors (58 % compliance) and 84 nursing personnel (47 % compliance) of the specialist departments concerned with internal medicine, rheumatology, urology, general and accident surgery. In hospital B the questionnaire was completed between March and July 2001 by a total of 40 doctors (54 %) and 91 nursing personnel (68 %) of two departments of internal medicine, surgery, neurosurgery and gynaecology. Comparable to other studies, the nursing personnel in both the hospitals rated the working conditions more negatively than the medical personnel. The differences, however, are more of a quantitative (number of frequency of problems) than of a qualitative nature (type or kind of problems). With both groups, problems connected with structural difficulties in working and with quality management were by far most important while the nursing personnel also underlined physical stress. Individual health condition were also classified more negatively by the nursing personnel than by the doctors, and the overall physical complaints of the nursing personnel were generally greater than with the average population, whereas medical personnel registered fewer complaints. Health promotion measures in hospitals may help to prevent negative developments. Such measures are too rarely translated into reality.

Retrieving biological activity from LukF-PV mutants combined with different S components implies compatibility between the stem domains of these staphylococcal bicomponent leucotoxins

Bicomponent leucotoxins, such as Panton-Valentine leucocidin, are composed of two classes of proteins, a class S protein such as LukS-PV, which bears the cell membrane binding function, and a class F protein such as LukF-PV, which interacts to form a bipartite hexameric pore. These leucotoxins induce cell activation, linked to a Ca(2+) influx, and pore formation as two consecutive and independently inhibitable events. Knowledge of the LukF-PV monomer structure has indicated that the stem domain is folded into three antiparallel beta-strands in the water-soluble form and has to refold into a transmembrane beta-hairpin during pore formation. To investigate the requirements for the cooperative assembly of the stems of the S and F components to produce biological activity, we introduced multiple deletions or single point mutations into the stem domains of LukF-PV and HlgB. While the binding of the mutated proteins was weakly dependent on these changes, Ca(2+) influx and pore formation were affected differently, confirming that they are independent events. Ca(2+) entry into human polymorphonuclear cells requires oligomerization and may follow the formation of a prepore. The activity of some of the LukF-PV mutants, carrying the shorter deletions, was actually improved. This demonstrated that a crucial event in the action of these toxins is the transition of the prefolded stem into the extended beta-hairpins and that this step may be facilitated by small deletions that remove some of the interactions stabilizing the folded structure.

The activin binding proteins follistatin and follistatin-related protein are differentially regulated in vitro and during cutaneous wound repair

Follistatin is a secreted protein that binds activin in vitro and in vivo and thereby inhibits its biological functions. Recently, related human and murine genes, designated follistatin-related gene (FLRG), were identified, and their products were shown to bind activin with high affinity. In this study we further characterized the murine FLRG protein, and we analyzed its tissue-specific expression and regulation in comparison with those of follistatin. Transient expression of the mouse FLRG protein in COS-1 cells revealed that the FLRG cDNA encodes a secreted glycoprotein. FLRG mRNA was expressed at high levels in the lung, the testis, the uterus and, particularly, the skin. Immunohistochemistry revealed the presence of FLRG in the basement membrane between the dermis and the epidermis and around blood vessels. FLRG mRNA expression was induced in keratinocytes by keratinocyte growth factor, epidermal growth factor and transforming growth factor-beta 1, and in fibroblasts by platelet-derived growth factor and epidermal growth factor. The induction was more rapid, but weaker, than that of follistatin. Most interestingly, both follistatin and FLRG were expressed during the wound healing process, but their distribution within the wound was different. The different expression pattern of FLRG and follistatin and their differential regulation suggest different functions of these activin-binding proteins in vivo.

The Mad1 transcription factor is a novel target of activin and TGF-beta action in keratinocytes: possible role of Mad1 in wound repair and psoriasis

Activin A, a member of the transforming growth factor beta (TGF-beta) superfamily, affects keratinocyte proliferation and differentiation in vitro and in vivo. However, little is known about the mechanisms of activin action in keratinocytes, and its target genes have not been identified. In this study, we demonstrate that activin A and TGF-beta1 directly induce the expression and activity of Mad1, an antagonist of the c-Myc transcription factor, in the human HaCaT keratinocyte cell line. Expression and activity of Mad1 was strongly induced by both factors in keratinocytes, although the intensity of induction was different for activin A and TGF-beta1. To determine a possible role of activin and TGF-beta in the regulation of mad1 expression in vivo, we analysed its expression during cutaneous wound repair when high levels of these factors are present. Expression of mad1 mRNA and protein, but not of other mad genes, increased significantly after skin injury, particularly in polymorphonuclear leukocytes and in suprabasal keratinocytes of the hyperproliferative epithelium. Elevated levels of mad1 mRNA were also detected in the hyperthickened epidermis of psoriatic patients. Since Mad1 regulates proliferation and/or differentiation of various cell types, our results suggest that this transcription factor mediates at least in the part the anti-mitotic and/or differentiation-inducing activities of TGF-beta and activin in keratinocytes.

Requirements for minus-strand transfer catalyzed by Rous sarcoma virus reverse transcriptase

We have examined the specific minus-strand transfer reactions that occur after the synthesis of minus strong-stop DNA and nonspecific strand switching on homopolymeric poly(rA) templates with different types of Rous sarcoma virus (RSV) reverse transcriptases. Three different types of reverse transcriptases can be isolated from virions of RSV: heterodimeric alphabeta and homodimeric alpha and beta. The mechanism of minus-strand transfer was examined using a model primer-template substrate corresponding to the 5'- and 3'-terminal RNA regions of the RSV genome. The results reveal that the RNase H activity of RSV reverse transcriptases is required for minus-strand transfer. Less than 2% of strand transfer of the extended product is detectable with RNase H-deficient enzymes. We could show that the alpha homodimer lacking the integrase domain can perform strand transfer almost as efficiently as the alphabeta and alphaPol heterodimers. In contrast, the activities of beta and Pol for minus-strand transfer are reduced. Furthermore, a two- to fivefold increase in minus-strand transfer activities was observed in the presence of human immunodeficiency virus type 1 nucleocapsid protein.

Commencing growth hormone replacement in adults with a fixed low dose. Effects on serum lipoproteins, glucose metabolism, body composition, and cardiovascular function

The safety and effects of a fixed low dose of growth hormone (GH), 0.17 mg/day was evaluated for 3 months, on glucose metabolism, serum lipids, body composition and cardiac function in 53 GH deficient adults aged 18-78 years. Body composition was determined by dual energy X-ray absorptiometry and total body water was determined by bioelectrical impedance. Echocardiography was used to assess cardiac function and bicycle ergonometry was used to determine exercise capacity. All investigations were performed at baseline and after 3 months. At 3 months, serum levels of insulin-like growth factor (IGF)-I, IGF binding protein (IGFBP)-3 and lipoprotein (a) and lean body mass were increased (P<0.05). Total and low density lipoprotein cholesterol levels and fat mass were reduced (P<0.05). There was an increase in the serum glucose value at 120 min after an oral glucose tolerance test performed at 3 months (P<0.05), no other changes in glucose metabolism or in cardiac function were noted. Side-effects were few and mild. This fixed low-dose regime resulted in improvements in body composition and lipid profile, without causing serious side effects. This is therefore a valid method to institute GH replacement in adults.

The Ca2+-binding proteins S100A8 and S100A9 are encoded by novel injury-regulated genes

To gain insight into the molecular mechanisms underlying cutaneous wound repair, we performed a large scale screen to identify novel injury-regulated genes. Here we show a strong up-regulation of the RNA and protein levels of the two Ca(2+)-binding proteins S100A8 and S100A9 in the hyperthickened epidermis of acute murine and human wounds and of human ulcers. Furthermore, both genes were expressed by inflammatory cells in the wound. The increased expression of S100A8 and S100A9 in wound keratinocytes is most likely related to the activated state of the keratinocytes and not secondary to the inflammation of the skin, since we also found up-regulation of S100A8 and S100A9 in the epidermis of activin-overexpressing mice, which develop a hyperproliferative and abnormally differentiated epidermis in the absence of inflammation. Furthermore, S100A8 and S100A9 expression was found to be associated with partially differentiated keratinocytes in vitro. Using confocal microscopy, both proteins were shown to be at least partially associated with the keratin cytoskeleton. In addition, cultured keratinocytes efficiently secreted the S100A8/A9 dimer. These results together with previously published data suggest that S100A8 and S100A9 are novel players in wound repair, where they might be involved in the reorganization of the keratin cytoskeleton in the wounded epidermis, in the chemoattraction of inflammatory cells, and/or in the defense against microorganisms.

Circumscripted pigmentations after iron injections-treatment with Q-switched laser systems

BACKGROUND AND OBJECTIVE

Cutaneous brown discolorations in the area of injection can be a cosmetically bothersome side effect from a parenteral iron treatment, and have not responded to an effective therapy until now.

STUDY DESIGN/PATIENTS AND METHODS

We report retrospectively on five patients who were treated with the Q-switched ruby and/or Nd:YAG laser for circumscripted siderosis after intramuscular or intravenous iron injection.

RESULTS

The number of required laser treatments was between 3 and 16. The clinical improvement after the first 2-4 sessions was the most impressive, especially after the application of the Nd:YAG laser. Hypopigmentation and scars did not develop. In one case hyperpigmentation appeared.

CONCLUSIONS

This study shows that there is an effective method of clearing persistent brown discolorations with few side effects after parenteral iron therapy, using Q-switched laser technology.

Characterization of two novel mutations in the glucocorticoid receptor gene in patients with primary cortisol resistance

OBJECTIVE

Primary glucocorticoid resistance is characterized by decreased sensitivity to cortisol signalling. We have performed genetic analysis of the glucocorticoid receptor (GR) gene in 12 unrelated patients with primary cortisol resistance as defined by a pathological dexamethasone suppression test.

METHODS

Exon specific polymerase chain reaction amplification of the GR gene and sequencing of each exon was carried out. The two mutations were characterized in vitro in terms of glucocorticoid driven reporter gene activity in a transient transfection assay and in a ligand binding assay. Molecular modelling of the R477H mutant was performed based on the X-ray structure of the GR-DNA binding domain.

RESULTS

Two novel mutations in the GR gene were found: R477H in the DNA-binding domain which is the first reported mutation in that region of the human GR gene and G679S in the ligand binding domain. The R477H mutation showed no transactivating capacity, whereas the G679S mutation had reduced transactivation capacity compared to the wild-type (wt) GR. When tested for ligand binding capacity, the G679S mutation had 50% binding affinity compared to the wt GR. The effect of the point mutation R477H was deduced by a comparison between the wt structure and the model of the mutant. The wt GR has direct and water mediated contact with the phosphate groups of the glucocorticoid responsive element (GRE) whereas, in the model, the mutation R477H has no contact with the GRE. The G679S mutation is located on the surface of the ligand binding domain, at a distance from the steroid-binding site. A previously reported polymorphism, AAT to AAC at amino acid position 766, was found in four of the patients.

CONCLUSIONS

In two of 12 patients with clinical glucocorticoid resistance, mutant forms of GR could be found. The glucocorticoid resistance in vivo in these two patients corresponds to impaired function of the two mutated GR forms in two in vitro assays. The relevance of the conservative polymorphism for the glucocorticoid insensitivity noted in these patients remains to be clarified.

Risk factors for leg injuries in female soccer players: a prospective investigation during one out-door season

The following possible risk factors for leg injuries in female soccer players were studied: age, anatomical alignment, generalized joint laxity, thigh muscle torque, muscle flexibility, ligamentous laxity of the knee and ankle joints, recent injuries, and duration of soccer exposure. A total of 146 players from 13 teams in the second and third Swedish divisions underwent clinical examination, isokinetic measurements of quadriceps and hamstring torques, and testing of postural sway of the legs. All soccer-related leg injuries resulting in absence from at least one scheduled practice session or game were recorded during one outdoor season (April-October). In 50 players there were 61 traumatic injuries, and 17 players sustained 19 overuse injuries. The overall injury incidence rate (traumatic and overuse) was 5.49/1000 h of soccer. Variables significantly increasing the risk of traumatic leg injuries included generalized joint laxity, low postural sway of the legs, hyperextension of the knee joint, and a low hamstring-to-quadriceps ratio during concentric action. Multivariate logistic regression showed hyperextension of the knee joint, a low postural sway, reduced H/Q ratio during concentric action, and a higher exposure to soccer to significantly increase the risk of traumatic leg injury. All five players who suffered an anterior cruciate ligament injury during the study period had a lower hamstring-to-quadriceps ratio during concentric action on the injured side than on their noninjured side.

Reliability of sports related functional tests with emphasis on speed and agility in young athletes

The aim of the present investigation was to test the reliability of two sports related functional tests, a speed test (slalom-test) and an agility test (hurdle-test). Eleven athletes aged 11 years (8 boys, 3 girls) participated voluntarily in the study. All subjects completed four different test sessions for both the slalom-test and the hurdle-test using six standard track hurdles placed at 2-m intervals along a 12-m length of track. There were no significant differences between testing sessions for either the slalom-test (P=0.99) or the hurdle-test (P=0.96), showing no systematic variation between test times. The intraclass correlation coefficients were 0.96 and 0.90 respectively, indicating a good reliability. We conclude that the slalom-test and the hurdle-test are reliable sports related functional tests for measuring speed and agility in groups of young athletic individuals.

O-GlcNAc expression in developing and ageing mouse brain

In order to understand whether there is a specific role for the posttranslational N-acetylglucosamine modification linked O-glycosidically (O-GlcNAc) to serine and threonine residues of proteins during development and/or ageing of the brain, we investigated the O-GlcNAc expression of early postnatal cerebellar neurons as well as of mouse brain of different ages. In all cells either in culture or of cryosections mainly the nuclei and nuclear membranes were stained with an O-GlcNAc specific monoclonal antibody. In cerebellar neurons in culture the level of expression could be manipulated by directly interfering with either the biosynthesis of GlcNAc or the removal of O-GlcNAc from proteins confirming the dynamic nature of this protein modification. O-GlcNAc was ubiquitously expressed in mouse brains from embryonic day 10 until late adulthood with some variations in expression strength from cell to cell. In addition, no significant difference in O-GlcNAc expression of subcellular fractions from brains of mice which age at an accelerated rate could be detected compared to normal mice. Taken together these observations support the view that the O-GlcNAc modification has important functional roles for physiological processes of neural cell throughout development, in adulthood and ageing.

The roles of activins in repair processes of the skin and the brain

A recent study from our laboratory demonstrated a strong upregulation of activin expression during cutaneous wound healing. To further analyze the role of activin A in skin morphogenesis and wound repair, we generated transgenic mice that overexpress activin A under the control of the keratin 14 promoter. The latter targets expression of transgenes to the basal, proliferating layer of the epidermis. Hetero- as well as homozygous transgenic animals were viable and fertile. However, they were smaller than non-transgenic littermates and they had smaller ears and shorter tails. Histological analysis of their skin revealed dermal hyperthickening, mainly due to the replacement of fatty tissue by connective tissue, and an increase in suprabasal, partially differentiated epidermal layers. After cutaneous injury, a strong enhancement of granulation tissue formation was observed. Furthermore, the extent of re-epithelialization was increased in some of the wounds. These data demonstrate that activin A is a potent stimulator of the wound healing process. Using an in vivo model of local brain injury, we found that activin A also plays a significant role in the early cellular response to neuronal damage. Expression of activin mRNA and protein is markedly upregulated within a few hours of injury. If applied exogenously, recombinant activin A is capable of rescuing neurons from acute cell death. Studying the interaction between bFGF, a well-established neuroprotective agent, which is currently being tested in stroke patients, and activin A, we arrived at the unexpected conclusion that it is the strong induction of activin A by bFGF which endows the latter with its beneficial actions in patients. These findings suggest that the development of substances directly targeting activin expression or receptor binding should offer new possibilities in the acute treatment of stroke and brain trauma.

Paracrine regulation of keratinocyte proliferation and differentiation

The histoarchitecture and function of the epidermis depend on a well-controlled balance between keratinocyte proliferation and differentiation. This balance is perturbed after skin injury, and imbalance is a characteristic feature of major human skin diseases such as psoriasis and epidermal cancers. Recent studies have highlighted the importance of fibroblast-derived soluble factors for the regulation of keratinocyte proliferation and differentiation. Therefore, identification of these paracrine-acting factors and the elucidation of their mechanisms of action are necessary for understanding epidermal homeostasis, repair and disease, and these approaches will offer new potential targets for drug therapy. Here, we review exciting recent findings on the identification, regulation and function of paracrine-acting cytokines in the skin. In particular, we describe the role of fibroblast-derived mitogens as regulators of keratinocyte proliferation and differentiation, and we summarize the regulation of these factors by keratinocyte-derived interleukin 1 that involves the transcription factors c-Jun and JunB.