Interaction between circadian rhythms and stress.

Life on earth has adapted to the day-night cycle by evolution of internal, so-called circadian clocks that adjust behavior and physiology to the recurring changes in environmental conditions. In mammals, a master pacemaker located in the suprachiasmatic nucleus (SCN) of the hypothalamus receives environmental light information and synchronizes peripheral tissues and central non-SCN clocks to geophysical time. Regulatory systems such as the hypothalamus-pituitary-adrenal (HPA) axis and the autonomic nervous system (ANS), both being important for the regulation of stress responses, receive strong circadian input. In this review, we summarize the interaction of circadian and stress systems and the resulting physiological and pathophysiological consequences. Finally, we critically discuss the relevance of rodent stress studies for humans, addressing complications of translational approaches and offering strategies to optimize animal studies from a chronobiological perspective.

Patient acceptance and diagnostic utility of automated digital image analysis of pigmented skin lesions.

BACKGROUND: Computerized analysis of pigmented skin lesions may help to increase diagnostic accuracy for melanoma, help to avoid unnecessary procedures and reduce health care costs. OBJECTIVES: We evaluated both the patient acceptance and diagnostic utility of such an analysis tool in a real clinical setting. METHODS: Two hundred nine consecutive patients (median age: 34 years, range: 2-73 years), who were concerned about a pigmented skin lesion, answered a questionnaire about their attitude towards computerized analysis and their confidence in the resulting findings. Using a dermoscopy analyser, their skin lesions (n = 219) were then grouped into the categories, benign, suspicious and malignant, and results were compared with those obtained by in-person examination of dermato-oncologic experts. RESULTS: More than half of the patients (n = 114) would accept the use of computer analysis for melanoma screening; although 16 (14.0%) patients would accept this method solely, 98 (86.0%) patients would prefer an additional in-person examination by a dermatologist. Of the 219 pigmented skin lesions, the dermoscopic experts rated 171 (78.1%) as benign, 36 (16.4%) as suspicious and 12 (5.5%) as malignant, whereas computer analysis revealed 102 (46.6%) benign, 78 (35.6%) suspicious and 39 (17.8%) malignant lesions. At the expense of specificity (48.8%), the sensitivity of computerized analysis was excellent (100%) and equal to that of in-person examination. CONCLUSIONS: Most patients would accept computer analysis for melanoma screening, some of them even without reservations. However, due to a high rate of false positive computer assessments, it cannot be recommended as a screening tool at this time.

Correlation with digital dermoscopic images can help dermatopathologists to diagnose equivocal skin tumours.

BACKGROUND: A variety of pigmented skin tumours can lead to diagnostic difficulties in dermatopathology. OBJECTIVES: To investigate whether the interobserver agreement between histopathological diagnoses of equivocal pigmented tumours made by two referral centres can be improved by additional use of dermoscopic images. MATERIAL AND METHODS: Retrospective study using 160 tumours excised in the pigmented skin lesions clinic in Graz and 141 from Tübingen. Tumours were diagnosed in the referring centres using clinical data, histopathology and, if required, immunohistochemistry. The tumours were initially diagnosed as 74 melanomas, 218 melanocytic naevi and nine nonmelanocytic tumours. Haematoxylin and eosin sections, patients' age and sex, tumour localization and digital dermoscopic images were then exchanged between the participating centres. Then, diagnoses were made initially based solely on dermatopathology and clinical information. After a washout phase, the same sections were reevaluated with the additional use of dermoscopic images. The main outcome measures were the Cohen's kappa-coefficients of the initial diagnoses of the centre submitting the cases and the diagnoses of the other centre without and with dermoscopy. RESULTS: The kappa-coefficient between the initial diagnoses with those made by the second centre without dermoscopy was 0.90 in Graz, 0.73 in Tübingen, and 0.81 overall. With the additional use of dermoscopy the kappa-value was invariably high with 0.89 in Graz, and improved to 0.87 in Tübingen, and to 0.88 overall. CONCLUSIONS: The additional use of digital dermoscopic images further improved the overall very good agreement of histopathological diagnoses between two referral centres.

Dermoscopy of Bowen's disease.

BACKGROUND: Dermoscopy improves the diagnostic accuracy in pigmented skin lesions, but it is also useful in the evaluation of nonpigmented skin tumours as it allows the recognition of vascular structures that are not visible to the naked eye. Bowen's disease (BD) or squamous cell carcinoma in situ is usually nonpigmented, but may also rarely be pigmented. Objective To describe the dermoscopic features in a series of pigmented and nonpigmented BD. METHODS: Dermoscopic images of 21 histopathologically proven BD were evaluated for the presence of various dermoscopic features. Each lesion was photographed using the Dermaphot (Heine Optotechnik, Herrsching, Germany), at 10-fold magnification, and the colour slides were scanned to digital format using a Kodak Photo CD system. RESULTS: The majority of cases of BD revealed a peculiar dermoscopic pattern characterized by glomerular vessels (90%) and a scaly surface (90%). In addition, in pigmented BD small brown globules regularly packed in a patchy distribution (90%), and structureless grey to brown pigmentation (80%) were observed. CONCLUSIONS: Dermoscopy can be helpful for diagnosing BD because of the presence of repetitive morphological findings such as glomerular vessels and a scaly surface. In pigmented BD, small brown globules and/or homogeneous pigmentation can be seen as well.

Regulation of protein kinase C by the cytoskeletal protein calponin.

Previous studies from this laboratory have shown that, upon agonist activation, calponin co-immunoprecipitates and co-localizes with protein kinase Cepsilon (PKCepsilon) in vascular smooth muscle cells. In the present study we demonstrate that calponin binds directly to the regulatory domain of PKC both in overlay assays and, under native conditions, by sedimentation with lipid vesicles. Calponin was found to bind to the C2 region of both PKCepsilon and PKCalpha with possible involvement of C1B. The C2 region of PKCepsilon binds to the calponin repeats with a requirement for the region between amino acids 160 and 182. We have also found that calponin can directly activate PKC autophosphorylation. By using anti-phosphoantibodies to residue Ser-660 of PKCbetaII, we found that calponin, in a lipid-independent manner, increased auto-phosphorylation of PKCalpha, -epsilon, and -betaII severalfold compared with control conditions. Similarly, calponin was found to increase the amount of (32)P-labeled phosphate incorporated into PKC from [gamma-(32)P]ATP. We also observed that calponin addition strongly increased the incorporation of radiolabeled phosphate into an exogenous PKC peptide substrate, suggesting an activation of enzyme activity. Thus, these results raise the possibility that calponin may function in smooth muscle to regulate PKC activity by facilitating the phosphorylation of PKC.

Thin and thick filament regulation of contractility in experimental cerebral vasospasm.

OBJECTIVE: Cerebral vasospasm is a potentially fatal consequence of aneurysmal subarachnoid hemorrhage and influences the prognosis of the patient. The purpose of this study was to evaluate the status of thin (actin) and thick (myosin) filament regulation of smooth muscle contraction in the double-subarachnoid hemorrhage canine model of cerebral vasospasm and to determine the effects of a kinase inhibitor reported to be effective in vasospasm, HA1077, on thin and thick filament regulation. METHODS: Cerebral vasospasm was assessed by vertebral angiography. Myosin regulatory light chain phosphorylation was measured using glycerol-urea gels, whereas protein levels of the thin filament-associated protein calponin were measured by Western blot. RESULTS: The basilar arteries of dogs in which subarachnoid hemorrhage was induced narrowed to 36% +/- 2.0% of their size on the first day (n = 12). The phosphorylation of the regulatory light chain tended to increase, but the change did not reach statistical significance (35% +/- 5.9% [n = 12] versus 25% +/- 4.8% [n = 10] in control arteries). In contrast to this increase, significant degradation of calponin was observed in the samples from vasospastic dogs (85.4% +/- 5.45% [n = 5] versus 15.2% +/- 6.21% [n = 5]; P < 0.01). Prophylactic treatment with intravenous injections of HA1077 at 0.67 mg/kg b.i.d. significantly inhibited vasospasm (diameters, 65% +/- 10.2% of Day 1 diameters [n = 5]; P < 0.05), and calponin degradation (57.8% +/- 13.9% [n = 4]) was substantially reduced. CONCLUSION: These data suggest that degradation of the thin filament-associated protein calponin plays a role in cerebral vasospasm and that the antivasospastic action of HA1077 is, at least in part, due to prevention of calponin degradation.

Calponin interaction with alpha-actinin-actin: evidence for a structural role for calponin.

The purpose of this study was to address the paradox of calponin localization with alpha-actinin and filamin, two proteins with tandem calponin homology (CH) domains, by determining the effect of these proteins on the binding of calponin to actin. The results show that actin can accommodate near-saturating concentrations of either calponin and alpha-actinin or calponin and filamin with little change or no change in ligand affinity. Little direct interaction occurred between alpha-actinin and calponin in the absence of actin, so this effect is not likely to explain the co-distribution of these proteins. Calponin, like alpha-actinin, induced elastic gel formation when added to actin. When alpha-actinin was added to newly formed calponin/actin gels, no change was seen in the mechanical properties of the gel compared to calponin and actin alone. However, when calponin was added to newly formed alpha-actinin/actin gels, the resulting gel was much stronger than the gels formed by either ligand alone. Furthermore, gels formed by the addition of calponin to alpha-actinin/actin exhibited a phenomenon known as strain hardening, a characteristic of mechanically resilient gels. These results add weight to the concept that one of the functions of calponin is to stabilize the actin cytoskeleton.

Fesselin: a novel synaptopodin-like actin binding protein from muscle tissue.

A novel actin binding protein has been isolated from chicken gizzard muscle. When isolated, a pair of proteins with apparent molecular weights of 79 kDa and 103 kDa are obtained; both proteins have a pI near 9.3. Peptide mapping indicates that these proteins are related. Antibodies against this protein cross-reacted with proteins from other smooth muscle containing tissues as well as skeletal and heart muscle. Traces of cross-reactive material were also detected in brain and kidney tissue. The affinity of this protein for actin is ca. 1x10(6) M(-1). Interestingly, this actin binding protein is a potent actin-bundling agent. A partial sequence analysis confirmed that there were no previously reported homologues in smooth muscle. However, considerable homology was found with the protein synaptopodin that is found in nervous tissue and kidney but is absent from muscle tissue. It is likely that the new protein is a member of the synaptopodin family. We call the smooth muscle actin binding protein fesselin.

Extracellular regulated kinase (ERK) interaction with actin and the calponin homology (CH) domain of actin-binding proteins.

An interaction between extracellular regulated kinase 1 (ERK1) and calponin has previously been reported (Menice, Hulvershorn, Adam, Wang and Morgan (1997) J. Biol. Chem. 272 (40), 25157-25161) and has been suggested to reflect a function of calponin as a signalling molecule. We report in this study that calponin binds to both ERK1 and ERK2 under native conditions as well as in an overlay assay. Using chymotryptic fragments of calponin, the binding site of ERK on calponin was identified as the calponin homology (CH) domain, an N-terminal region of calponin found in other actin-binding proteins. ERK also bound, in a gel overlay assay, alpha-actinin, a protein with two tandem CH domains, as well as a 27 kDa thermolysin product of alpha-actinin containing the CH domains of alpha-actinin. The CH domain of calponin could compete with intact calponin or alpha-actinin for ERK binding. Titration of acrylodan-labelled calponin with ERK gave a K(a) of 6x10(6) M(-1) and titration of acrylodan-labelled calponin with a peptide from the alphaL16 helix of ERK gave a K(a) of 1x10(6) M(-1). Recombinant ERK was found to co-sediment with purified actin and induced a fluorescence change in pyrene-labelled F-actin (K(a)=5x10(6) M(-1)). The interaction of ERK with CH domains points to a new potential function for CH domains. The interaction of ERK with actin raises the possibility that actin may provide a scaffold for ERK signalling complexes in both muscle and non-muscle cells.

Caldesmon: binding to actin and myosin and effects on elementary steps in the ATPase cycle.

The actin binding protein caldesmon inhibits the actin-activation of myosin ATPase activity. The steps in the cycle of ATP hydrolysis that caldesmon could inhibit include: (1) the binding of myosin to actin, (2) the transition between any two actin-myosin states and (3) the distribution between inactive and active states of actin. The analysis of these possibilities is complicated because caldesmon binds to both myosin and actin and because each caldesmon molecule binds to several actin monomers. This paper reviews procedures for analysing these interactions and summarizes current information on the stability and dynamics of the interaction of caldesmon with actin and myosin. Possible effects of caldesmon on transitions within the ATPase cycle of actomyosin are also discussed.

PKC-dependent signalling mechanisms in differentiated smooth muscle.

Protein kinase C (PKC) is now known to play an important physiological role in essentially all cell types. This review will focus on what is known about the kinase in contractile differentiated smooth muscle. Current knowledge on the molecular structure of PKC isoforms will be discussed as they relate to mechanisms of translocation and targeting of the kinase within smooth muscle cells. Studies performed on PKC-dependent signalling pathways in differentiated smooth muscle cells will be discussed with emphasis on studies form our laboratory, especially discussing thin filament linked pathways. Thick filament linked PKC-dependent pathways will be described in more detail elsewhere in this monograph.

[Polyneuritis and myositis in Trypanosoma gambiense infection]. / Polyneuritis und Myositis bei Trypanosoma-gambiense-Infektion.

During a four-week trip to Nigeria a 54-year-old German developed a fever of 39 degrees C. Later on he had lymphadenopathy, pretibial oedema, dyspnoea and weight loss. After 16 weeks a wreath-like pale pink skin rash, increased pulse rate with pulse deficit and hepatosplenomegaly were noted. Abnormal laboratory findings were an increased blood sedimentation rate (95 mm), raised immunoglobulin M (483 mg/dl), haemoglobin of 12.0 g/dl, mean corpuscular volume of 76 fl and Borrelia IgM antibody titre of 1:512. The electrocardiogram was suggestive of myocarditis: the cardiac symptoms were controlled with digoxin and verapamil. The patient's general condition deteriorated while he was receiving antibiotic treatment with tetracycline and penicillin. Cerebrospinal fluid (CSF) showed an increased cell count (39/microliters) and albumin (0.98 g/dl). There was a mild, predominantly proximal, tetraplegia which--on the basis of electromyographic and biopsy findings--was thought to be due to polyneuritis and myositis. At this stage blood smear and CSF examination revealed Trypanosoma. He thereupon received suramin (1.0 g) and prednisolone (120 mg down to 40 mg) daily, to which melarsoprol was added after 6 days (0.5 ml up to 5.0 ml daily for 36 days). Almost all symptoms then regressed within 6 weeks.

[Ileus symptoms due to 3 distinctively differentiated small intestine carcinomas in nontropical sprue]. / Ileussymptomatik durch drei unterschiedlich differenzierte Dünndarmkarzinome bei einheimischer Sprue.

Recently recurring abdominal pain, bouts of diarrhoea and weight-loss of 15 kg developed in a 50-year-old woman who had for 18 years been treated by diet for nontropical sprue. She was hospitalized for signs of mechanical ileus. Radiological examination revealed three stenosing small intestine tumours, one of them obstructing the lumen. After resection of the affected segments, with end-to-end anastomosis, histological, histological examination of the surgical specimens demonstrated three small intestine carcinomas of different grades of differentiation. The largest tumour had already metastasized to four regional lymph nodes. This case illustrates the potentially precancerous nature of nontropical sprue which has been present for many years and thus requires careful follow-up.

[The effect of prednisolone on the development of the galactosamine hepatitis of young and old rats (author's transl)]. / Der einfluss von Prednisolon auf die Entwicklung der Galaktosamin-Hepatitis junger und alter Ratten

The present work reports on kinetic and morphological studies of one hundred female albino rats after the administration of galactosamine and galactosamine and prednisolone. The results demonstrate a significant higher increase of the serum transaminasess got and gpt in the older than in the younger rats as well as a protecting effect of prenisolone against galactosamine produced disturbances. In the thirty months old rats the protection against morphological and biochemical disturbances was only demonstrable for the first twelve hours after the administration of galactosamine.