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S Thomsen

Publications and source records attributed to S Thomsen.

At least 19 recordsLinked to original sources
PubMed2006

Active zone assembly and synaptic release.

Neurotransmitter release at chemical synapses occurs when synaptic vesicles fuse to the presynaptic membrane at a specialized site termed the active zone. The depolarization-induced fusion is highly dependent on calcium ions, and, correspondingly, the transmission characteristics of synapses are thought to be influenced by the spatial arrangement of voltage-gated calcium channels with respect to vesicle release sites. Here, we review the involvement of the Drosophila Bruchpilot (BRP) protein in active zone assembly, a process that is required for the clustering of presynaptic calcium channels to ensure efficient vesicle release.

Animals↗
PubMed2005

Histological evidence for the role of mechanical stress in modulating thermal denaturation of collagen.

The hyperthermia and thermal denaturation literatures reveal a time-temperature equivalency when heating cells or connective tissues: thermal damage increases with increasing temperature (for the same duration) and increases with increasing duration (for the same temperature). Recent findings conversely suggest that increasing the mechanical loading on a tissue during heating decreases the thermal damage (for a given temperature and duration of heating). Surprisingly, however, there are few histological correlates of such damage. In this paper, we show that progressive light microscopic changes - swelling of collagen bands, thickening of collagen-rich layers, hyalinization, and loss of birefringence approximately - correlate very well with both increased heating times and decreased mechanical loading. Increased mechanical stress is thus thermally protective and should be considered in the design of clinical procedures that use heating to treat diseases or injuries.

Animals↗
PubMed2005

Control of foot differentiation in Hydra: phylogenetic footprinting indicates interaction of head, bud and foot patterning systems.

Homeodomain transcription factor CnNK-2 seems to play a major role in foot formation in Hydra. Recently, we reported in vitro evidence indicating that CnNK-2 has autoregulatory features and regulates expression of the morphogenetic peptide pedibin. We proposed that CnNK-2 and pedibin synergistically orchestrate foot differentiation processes. Here, we further analyzed the regulatory network controlling foot formation in Hydra. By phylogenetic footprinting we compared the CnNK-2 5'-flanking sequence from two closely related species, Hydra vulgaris and Hydra oligactis. Unexpectedly, we detected a highly conserved binding site for HNF-3beta, a vertebrate Forkhead transcription factor, in the CnNK-2 5'-flanking region. The Hydra HNF-3beta homolog budhead is predominantly expressed in the apical region of the body column and early during budding. Budhead is absent from tissue expressing CnNK-2 and thought to be involved in determining tissue for head differentiation. By electrophoretic mobility shift assays we demonstrate an in vitro interaction between recombinant budhead protein and the interspecific conserved HNF-3beta binding motif in the CnNK-2 5'-flanking region. Our results strengthen the view of CnNK-2 as an important regulator during foot patterning processes. Furtheron, they point to budhead as a candidate for a transcriptional regulator of CnNK-2 and to an interaction of foot and head patterning processes in Hydra on the molecular level.

Animals↗
PubMed2004

Control of foot differentiation in Hydra: in vitro evidence that the NK-2 homeobox factor CnNK-2 autoregulates its own expression and uses pedibin as target gene.

The foot of the simple metazoan Hydra is a highly dynamic body region of constant tissue movement, cell proliferation, determination and differentiation. Previously, two genes have been shown to participate in the development and differentiation of this body region: homeodomain factor CnNK-2 and signal peptide pedibin [Dev. Biol. 180 (1996) 473; Development 126 (1999) 517; Development 122 (1996) 1941; Mech. Dev. 106 (2001) 37]. CnNk-2 functions as transcriptional regulator and is responsive to changes in the positional value while the secreted peptide pedibin serves as "extrinsic" positional signal. Exposure of polyps to pedibin increases the spatial domain of CnNK-2 expression towards the gastric region, indicating that positional signals are integrated at the cis-regulatory region of CnNK-2. In the present study, to elucidate the molecular basis of the interaction of CnNK-2 and pedibin, we characterized the 5' regulatory regions of both genes. Within the CnNK-2 5' upstream region, electrophoretic mobility shift assays showed that putative NK-2 binding motifs are specifically bound by both nuclear protein from Hydra foot and by recombinant CnNK-2, suggesting that CnNK-2 might autoregulate its own expression. This is the first indication for an autoregulatory circuit in Hydra. In addition, we also identified NK-2 binding sites in the cis-regulatory region of the pedibin gene, indicating that this gene is one of the targets of the transcription factor CnNK-2. On the basis of these results, we present a model for the regulatory interactions required for patterning the basal end of the single axis in Hydra which postulates that CnNK-2 together with pedibin orchestrates foot specific differentiation.

Animals↗
PubMed2004

Fifty ways to leave your rubber: how men in Mombasa rationalise unsafe sex.

OBJECTIVE: To explore the reasons why men who have sex with sex workers in Kenya refuse to use condoms in order to develop potential interventions that might help to overcome these barriers. METHODS: We conducted participant observations over a period of 2 months in the bars, discos, shebeens, and guesthouses of Mombasa, Kenya, where many of the sexual transactions are initiated. RESULTS: Analysis of the participant observations revealed at least 50 reasons for not using a condom, which we grouped into six categories: condoms are not pleasurable, condoms are defective, condoms are harmful, condoms are unnecessary, condoms are too hard to use, and external forces prohibit using condoms. CONCLUSIONS: Some of the reasons men say they do not use condoms would be difficult to affect directly. Others are the result of gaps in knowledge and have not been impacted through better communication strategies. Finally, some of the reasons for not using condoms, such as men's weaknesses, and the loss of pleasure, could possibly be addressed through the introduction of female controlled devices. However, the most important conclusion of this paper is that men who pay for sex do so because it is pleasurable and many men do not find the male condom pleasurable. Therefore, messages targeted at men who have sex with sex workers may not be 100% successful if they only emphasise the benefits of condom use as disease control.

Attitude to Health↗
PubMed2001

A comparative study of the experiences of violence of English and Swedish mental health nurses.

Recent studies suggest that violence in health care environments, especially mental health care, appears to be increasing. Although there is a lack of cross-cultural studies to prove it, this increase in violence would seem to be an international phenomenon. The present study sought to compare the extent and nature of violence encountered by mental health nurses in Sweden and England. Systematic studies of violence have previously been carried out independently in both countries but this was the first attempt to compare levels of violence. Clearly defined study protocols were put in place, an operational definition of 'violence' adhered to, and random samples recruited. A specially designed questionnaire was sent to every subject (Swedish nurses n=720; English nurses n=296) enquiring about the extent of nurses' exposure to violence, the nature and severity of the violence experienced, and the effect of violence on self-esteem and job satisfaction. Significant differences were found with English nurses experiencing more violence than their Swedish counterparts. Yet support for English nurses appeared to be less good than for Swedish nurses. Reasons for the differences are discussed along with possible measures to minimise the frequency of violence against nurses and the negative effects on their work.

Adult↗
PubMed2000

An examination of nonresponse in a work environment questionnaire mailed to psychiatric health care personnel.

Nonresponse to surveys, which seems to plague work environment studies and studies of health care personnel in particular, may pose problems of generalizability and validity. The aim of this study was to provide an estimate of nonresponse error in a self-administered survey concerning the work environment of psychiatric health care personnel. A random sample of 10% of the original survey population (N = 693) was selected to participate in a telephone follow-up of a postal survey that had a response rate of 51%. There were no differences between the responders and nonresponders to the postal survey on the exposure or outcome variables. There was no evidence of nonresponse bias in this study, although recall bias may have been a problem. In those cases in which generalizability is deemed important, it is recommended that nonresponse studies be regularly carried out when response rates are less than 100%.

Adult↗
PubMed2000

Changes in collagen I and collagen III metabolism in patients with generalized atopic eczema undergoing medium-dose ultraviolet A1 phototherapy.

Fourteen patients suffering from acute, exacerbated atopic eczema were screened for changes in collagen I and collagen III metabolism in serum (n = 11), urine (n = 11) and skin biopsies (n = 9) before and after medium-dose ultraviolet (UV) A1 phototherapy (15 exposures of 50 J/cm2 over a 3-week period, total dose 750 J/cm2). Mature collagen I and, to a lesser extent, mature collagen III were found to be decreased after the therapy in skin samples from the irradiated patients. As markers of collagen I degradation, the cross-links pyridoline and deoxypyridoline were analysed in urine using high-performance liquid chromatography. Both cross-links were found to be mildly increased after UVA1 phototherapy, without reaching statistical significance. As markers of de novo collagen synthesis we screened for the procollagen I-carboxyterminal peptide (PICP) and procollagen III-aminoterminal peptide (PIIINP) levels in serum and skin. The ratio of PICP to PIIINP in serum dropped significantly after the UVA1 phototherapy, suggesting a different impact of UVA1 on the two collagens. These findings were paralleled by a diminished ratio of PICP to PIIINP in tissue samples. Staining for matrix metalloproteinase 1 (MMP-1) and its specific counterpart, tissue inhibitor of MMP-1 (TIMP-1), showed slight increases for both proteins by therapeutic UVA1; this was also seen in serum for TIMP-1 but not MMP-1. In our study, high-energy UVA1 doses induced changes of the skin collagens in patients with atopic eczema which are measurable by their metabolites in serum and urine.

Chromatography, High Pressure Liquid↗
PubMed2000

Optimizing the therapeutic approach in tinea capitis of childhood with itraconazole.

BACKGROUND: Tinea capitis is the most common dermatophytosis of childhood with increasing incidence. Whereas griseofulvin is considered by many as the mainstay of treatment, newer oral antifungal agents, including fluconazole, itraconazole and terbinafine have demonstrated higher efficacy, resulting in shorter treatment durations. OBJECTIVES: We aimed to determine the optimum regimen for the treatment of childhood tinea capitis with itraconazole. METHODS: A mycological culture outcome-dependent combination of a 28-day continuous and facultative additional 14-day courses with itraconazole was used in 42 children (20 girls; 22 boys) aged 12-140 months (mean 66) with tinea capitis due to Microsporum canis (n = 26) and Trichophyton violaceum (n = 16). The drug was given orally according to the patients' body weight (50 mg daily for < 20 kg; 100 mg daily for > or = 20 kg) over 4 weeks. Direct microscopy and fungal culture as a parameter for efficacy were repeated 2 weeks after termination of treatment. Assessment of efficacy was based on the evaluation of results from light microscopy and culture at 8 weeks after initiation of treatment, and in the case of a further positive mycological culture at 14 and 20 weeks, respectively. A positive fungal culture at these times resulted in an additional course for 2 weeks with the initially chosen itraconazole dosage. RESULTS: In 34 of 42 patients a single 4-week course of itraconazole resulted in a complete mycological cure of lesions as demonstrated by light microscopy and mycological culture. Four of 42 patients had to be treated by a second itraconazole course for 2 weeks, and four children received a third course of itraconazole for 2 weeks until all lesions showed negative direct microscopy and mycological culture. No abnormal haematological or biochemical results occurred. Apart from transient, completely reversible indigestion in two children, no side-effects were observed. CONCLUSIONS: A culture-based 28-day continuous therapeutic regimen plus facultative cultural outcome-dependent additional 14-day courses of a body weight-adapted dosage of itraconazole in tinea capitis due to M. canis and T. violaceum is discussed; this offers the advantage of an effective therapy with complete negative direct microscopy as well as negative cultural results, within a shorter active treatment period (cf. previous studies with continuous administration of itraconazole).

Adolescent↗
PubMed2000

Autofluorescence patterns in short-term cultures of normal cervical tissue.

Fluorescence spectroscopy has potential to improve cervical precancer detection. The relationship between tissue biochemistry and fluorescence is poorly understood. The goal of this study was to characterize normal cervical autofluorescence, using fresh tissue short-term tissue cultures and epithelial cell suspensions. Transverse, short-term tissue cultures were prepared from 31 cervical biopsies; autofluorescence images were obtained at 380 and 460 nm excitation. Fluorescence excitation-emission matrices were measured from normal, precancerous and cancerous cervical cell suspensions. Observed fluorescence patterns contrast those reported for frozen-thawed tissue, and were placed into groups with (1) bright epithelial and weak stromal fluorescence; (2) similar epithelial and stromal fluorescence; and (3) weak epithelial and bright stromal fluorescence. The average ages of women in the groups were 30.9, 38.0 and 49.2 years. Epithelial fluorescence intensity was similar in Groups 1 and 2, but weaker in Group 3. Stromal intensity was similar in Groups 2 and 3, but weaker in Group 1. The ratio of epithelial to stromal fluorescence intensity was significantly different for all groups. EEMs of cell suspensions showed peaks consistent with tryptophan, reduced form of nicotinamide adenine dinucleotide (phosphate) and flavin adenine dinucleotide. Short-term tissue cultures represent a novel, biologically appropriate model to understand cervical autofluorescence. Our results suggest a biological basis for the increased fluorescence seen in older, postmenopausal women.

Adult↗
PubMed1999

Activation of caspase-3 in axotomized rat retinal ganglion cells in vivo.

Recently, we have shown that inhibition of caspase-3-like caspases is the most effective treatment strategy to protect adult rat retinal ganglion cells from secondary death following optic nerve transection. In the present study, we localized active caspase-3 in axotomized retinal ganglion cells in vivo and demonstrated a co-localization of the active p20 fragment and TUNEL-staining in some of these cells. In line with this, we detected an enhanced cleavage and activity of caspase-3 protein in retinal tissue after lesion, while caspase-3 mRNA expression remained unchanged. These data suggest caspase-3 as an important mediator of secondary retinal ganglion cell death following axotomy in vivo.

Animals↗
PubMed1999

Computer-controlled bipolar endotubal sterilization is successful in a rabbit model.

OBJECTIVE: To determine the efficacy of a computer-controlled bipolar endotubal catheter system designed to accomplish safe, effective, and inexpensive female sterilization in preventing pregnancy in a rabbit model. DESIGN: Prospective controlled study. SETTING: University animal care facility. ANIMAL(S): Sixty healthy virginal female New Zealand white rabbits. INTERVENTION(S): Rabbits were assigned to the following groups: [1] endotubal radiofrequency minimal energy (95 degrees C) treatment; [2] endotubal radiofrequency maximal energy (105 degrees C) treatment; [3] endouterine radiofrequency (105 degrees C) treatment; [4] nonsurgical control; [5] laparotomy-only control; [6] endotubal radio-frequency sham control; and [7] external Kleppinger forceps bipolar cautery control. Rabbits were mated at 4 or 12 weeks after treatment. MAIN OUTCOME MEASURE(S): Pregnancy outcomes in treated animals and nontreated controls. RESULT(S): No pregnancies were observed in any of the uterine horns in which minimal or maximal energy was delivered to the fallopian tubes or uterus, although pregnancy occurred in one horn as a result of the delivery of energy below the radiofrequency minimum of 95 degrees C. The outcomes of the treatment groups were significantly different from those of the nonsurgical and sham surgical control groups. CONCLUSION(S): With adequate tissue heating, 100% sterilization efficacy was achieved with a new, computer-controlled bipolar catheter, whereas pregnancies occurred in all untreated control groups. If human studies support these results, the goal of a safe, effective means of transcervical sterilization may be realized.

Animals↗
PubMed1999

A comparative study of the perceptions of British mental health nurses and psychiatrists of their work environment.

This comparative study of the perceptions of mental health nurses and psychiatrists about aspects of their work environment was undertaken in the West Midlands in England. The aim of the study was to ascertain the extent to which the environment in which mental health professionals' work impacts on their own mental and physical well-being. Seventy-four psychiatrists and 301 mental health nurses responded to a postal questionnaire. Analysis of data indicated that significant differences exist between nurses and psychiatrists in their working conditions, their physical working environment, their sources of support with a work-related problem, and the effects of their work on their own mental and physical health. The main recommendation derived from this study was to improve communication between mental health professionals and their managers by giving more structured feedback and guidance about one's work performance. This may help to alleviate the mental strain many mental health professionals experience in their work.

Adaptation, Psychological↗
PubMed1999

Individual and organizational well-being in psychiatric nursing: a cross-cultural study.

Although health care systems around the world are undergoing rapid changes, there is an absence of comparative studies of how these changes affect nurses' well-being and work life. The purpose of this study was (i) to identify and describe possible differences between the psycho-social work environments of English and Swedish mental health nurses, and (ii) to attempt to explain these differences. 1016 psychiatric nurses from Stockholm (Sweden) and Birmingham (England) responded to a postal questionnaire on their psycho-social work environment and feelings of professional fulfillment, mental energy and work-related exhaustion. The study was given ethical clearance in Stockholm and Birmingham. Results indicated that while the English nurses rated their organizational well-being more favourably, Swedish psychiatric nurses reported greater individual well-being than their counterparts. Multiple regression analyses indicated that self-esteem was important for explaining mental energy and work-related exhaustion, but less so for explaining professional fulfillment, which was predicted primarily by organizational factors. When controlling for self-esteem, which was higher amongst the Swedish nurses, the differences in professional fulfillment and mental health were no longer significant. Reasons for the differences in self-esteem and experiences of the workplace are discussed. Low response rate may have contributed to a selection bias.

Adult↗
PubMed1999

Violence in mental health care: the experiences of mental health nurses and psychiatrists.

Violence against mental health service personnel is a serious workplace problem and one that appears to be increasing. This study aimed to ascertain the extent and nature of violence against mental health nurses and psychiatrists, and to identify what support, if any, they received following exposure to violence. Mental health staff working within five West Midlands Trusts in the United Kingdom were surveyed using a postal questionnaire to investigate the extent and nature of violence they encountered in their daily work. There was an overall response rate of 47%, which included a response rate for psychiatrists of 60% (n=74) and for mental health nurses of 45% (n=301). Though both groups experienced violence at work, nurses were found: to have been exposed to violence significantly more during their career; to have been a victim of violence within the previous 12 months of the survey; and to have suffered a violent incident involving physical contact. Whilst a higher proportion of nurses than psychiatrists received some support following a violent incident, a large proportion of both groups did not receive any, although most felt in need of it. The implications of this study for training and management are discussed.

Adult↗
PubMed1999

Feelings of professional fulfilment and exhaustion in mental health personnel: the importance of organisational and individual factors.

BACKGROUND: Mental health personnel are at high risk for mental illness, burnout and suicide. Previous studies of this group of professionals have indicated the importance of organisational factors in explaining burnout, or exhaustion, and work satisfaction. This study looks more systematically at the contribution of organisational and individual factors to work-related exhaustion and to professional fulfillment, an expanded version of job satisfaction. METHODS: A cross-sectional study of 1, 051 psychiatrists and mental health nurses in the city of Stockholm was carried out by postal questionnaire with a previously validated instrument. Multiple and logistic regressions were used to identify predictors of exhaustion and professional fulfillment. RESULTS: Organisational characteristics were found to be more important than individual characteristics in predicting exhaustion and professional fulfillment in mental health professionals. CONCLUSIONS: The results indicate that the psychosocial work environment and well-being of mental health professionals can be improved by concentrating on organisational factors such as efficiency, personal development and goal quality.

Adult↗
PubMed1999

Making family-centred care a reality.

The role of families in caring for their sick children has evolved over the last century. Where once they were banned from hospitals, families now play an integral part in the care of their children, whether in hospital or at home.

Cerebral Palsy↗