Eccrine porocarcinoma (malignant eccrine poroma): a clinicopathologic study of 69 cases

The clinicopathologic characteristics of 69 cases of eccrine porocarcinoma (EP) have been studied. Seven cases of purely in situ disease are included. Forty patients were female, 29 male with ages ranging from 29 to 91 years (mean 73 years). The lower extremity represented the single most common site (44%). Other common sites were the trunk (15 cases, 24%) and head (11 cases, 18%). The histologic diagnosis of EP was predicated on the basis of an irregular tumor at least partly formed of characteristic poromatous basaloid epithelial cells displaying ductal differentiation, and significant cytologic atypia. Forty-seven tumors (68%) contained mature well-formed eccrine ducts having an eosinophilic luminal cuticle, with the remaining tumors containing small ill-formed ducts and/or intracytoplasmic lumina. All ducts were discernible via light microscopy and in 49 cases were highlighted with DPAS stain and/or CEA/EMA immunocytochemistry. A variant with a broad pushing tumor margin and marked nuclear pleomorphism showed some resemblance to proliferative bowenoid dysplasia. In 11 cases (18%) the tumors appeared to arise in continuity with a benign preexistent poroma. A variety of histologic patterns were displayed including clear, squamous, and spindle cell differentiation, mucus cell metaplasia, and colonization by melanocytes. Lymphovascular invasion was present in 9 cases (15%). Three cases showed pagetoid extension of malignant cells (epidermotropism) and appeared to be multifocal. Follow-up was available in 54 patients (78%) with 9 (17%) experiencing local recurrence, 10 developing lymph node metastases (19%), and 6 (11%) experiencing distant metastases or death. Mitoses, the presence of lymphovascular invasion, and tumor depth >7 mm were associated with a poorer prognosis. Dividing tumors into those with a "pushing" or "infiltrating" advancing margin was also predictive of outcome with the latter having an increased risk of local recurrence. This report, the largest series of EP to date, suggests that the incidence of aggressive behavior is less than popularly believed. Furthermore, EP can display a wide variety of histologic patterns that may lead to diagnostic error in the unwary. The large number of cases in this series enables a reliable evaluation of prognostic parameters. A more aggressive clinical course may be indicated by more than 14 mitoses per high power field (hazard ratio [HR] for death 17.0, 95% confidence interval [CI] 2.71-107), lymphovascular invasion by tumor (HR 4.41, CI 1.13-17.2), and depth >7 mm (HR 5.49, CI 1.0-30.3). Thus, mitoses, lymphovascular invasion, and tumor depth should be evaluated in these tumors. We also suggest that tumors presenting an "infiltrative" advancing margin are particularly prone to local recurrence and require wide excision with close attention to the surgical margins by the reporting pathologist.

Demonstration of accuracy and clinical versatility of mutual information for automatic multimodality image fusion using affine and thin-plate spline warped geometric deformations

This paper applies and evaluates an automatic mutual information-based registration algorithm across a broad spectrum of multimodal volume data sets. The algorithm requires little or no pre-processing, minimal user input and easily implements either affine, i.e. linear or thin-plate spline (TPS) warped registrations. We have evaluated the algorithm in phantom studies as well as in selected cases where few other algorithms could perform as well, if at all, to demonstrate the value of this new method. Pairs of multimodal gray-scale volume data sets were registered by iteratively changing registration parameters to maximize mutual information. Quantitative registration errors were assessed in registrations of a thorax phantom using PET/CT and in the National Library of Medicine's Visible Male using MRI T2-/T1-weighted acquisitions. Registrations of diverse clinical data sets were demonstrated including rotate-translate mapping of PET/MRI brain scans with significant missing data, full affine mapping of thoracic PET/CT and rotate-translate mapping of abdominal SPECT/CT. A five-point thin-plate spline (TPS) warped registration of thoracic PET/CT is also demonstrated. The registration algorithm converged in times ranging between 3.5 and 31 min for affine clinical registrations and 57 min for TPS warping. Mean error vector lengths for rotate-translate registrations were measured to be subvoxel in phantoms. More importantly the rotate-translate algorithm performs well even with missing data. The demonstrated clinical fusions are qualitatively excellent at all levels. We conclude that such automatic, rapid, robust algorithms significantly increase the likelihood that multimodality registrations will be routinely used to aid clinical diagnoses and post-therapeutic assessment in the near future.

Homology in structural organization between E. coli ClpAP protease and the eukaryotic 26 S proteasome

Energy-dependent protein degradation is carried out by large multimeric protein complexes such as the proteasomes of eukaryotic and archaeal cells and the ATP-dependent proteases of eubacterial cells. Clp protease, a major multicomponent protease of Escherichia coli, consists of a proteolytic component, ClpP, in association with an ATP-hydrolyzing, chaperonin-like component, ClpA. To provide a structural basis for understanding the regulation and mechanism of action of Clp protease, we have used negative staining electron microscopy and image analysis to examine ClpA and ClpP separately, as well as active ClpAP complexes. Digitized images of ClpP and ClpA were analyzed using a novel algorithm designed to detect rotational symmetries. ClpP is composed of two rings of seven subunits superimposed in bipolar fashion along the axis of rotational symmetry. This structure is similar to that formed by the beta subunits of the eukaryotic and archaeal proteasomes. In the presence of MgATP, ClpA forms an oligomer with 6-fold symmetry when viewed en face. Side views of ClpA indicate that the subunits are bilobed with the respective domains forming two stacked rings. ClpAP complexes contain a tetradecamer of ClpP flanked at one or both ends with a hexamer of ClpA, resulting in a symmetry mismatch between the axially aligned molecules. Our findings demonstrate that, despite the lack of sequence similarity between ClpAP and proteasomes, these multimeric proteases nevertheless have a profound similarity in their underlying architecture that may reflect a common mechanism of action.

High-resolution structure of an HIV zinc fingerlike domain via a new NMR-based distance geometry approach

A new method is described for determining molecular structures from NMR data. The approach utilizes 2D NOESY back-calculations to generate simulated spectra for structures obtained from distance geometry (DG) computations. Comparison of experimental and back-calculated spectra, including analysis of cross-peak buildup and auto-peak decay with increasing mixing time, provides a quantitative measure of the consistence between the experimental data and generated structures and allows for use of tighter interproton distance constraints. For the first time, the "goodness" of the generated structures is evaluated on the basis of their consistence with the actual experimental data rather than on the basis of consistence with other generated structures. This method is applied to the structure determination of an 18-residue peptide with an amino acid sequence comprising the first zinc fingerlike domain from the gag protein p55 of HIV. This is the first structure determination to atomic resolution for a retroviral zinc fingerlike complex. The peptide [Zn(p55F1)] exhibits a novel folding pattern that includes type I and type II NH-S tight turns and is stabilized both by coordination of the three Cys and one His residues to zinc and by extensive internal hydrogen bonding. The backbone folding is significantly different from that of a "classical" DNA-binding zinc finger. Residues C(1)-F(2)-N(3)-C(4)-G(5)-K(6) fold in a manner virtually identical with the folding observed by X-ray crystallography for related residues in the iron domain of rubredoxin; superposition of all main-chain and Cys side-chain atoms of residues C(1)-K(6) of Zn(p55F1) onto residues C(6)-Y(11) and C(39)-V(44) of rubredoxin gives RMSDs of 0.46 and 0.35 A, respectively. The side chains of conservatively substituted Phe and Ile residues implicated in genomic RNA recognition form a hydrophobic patch on the peptide surface.

Bladder tumor staging: comparison of contrast-enhanced CT, T1- and T2-weighted MR imaging, dynamic gadolinium-enhanced imaging, and late gadolinium-enhanced imaging

PURPOSE

To evaluate the accuracy of contrast material-enhanced computed tomography (CT), unenhanced T1- and T2-weighted magnetic resonance (MR) imaging, and dynamic gadolinium-enhanced spoiled gradient-echo MR imaging in the staging of bladder cancer.

MATERIALS AND METHODS

Thirty-six patients with histologically proved bladder cancer were prospectively examined with CT and MR imaging before tumor resection. Images were evaluated in a blinded fashion.

RESULTS

All methods depicted tumors comparably well. Staging was correct in 16 of 29 patients (55%) with CT and 27 of 36 patients (75%) overall with MR imaging. Overstaging was the most common error, and both CT and MR imaging were more accurate for higher-staged tumors.

CONCLUSION

CT and MR imaging perform well in the detection of tumors but are less accurate in staging. Dynamic gadolinium-enhanced MR imaging is better than other techniques, but the difference is not statistically significant.

Molecular layer-by-layer assembled thin-film composite membranes for water desalination

Molecular layer-by-layer (mLbL) assembled thin-film composite membranes fabricated by alternating deposition of reactive monomers on porous supports exhibit both improved salt rejection and enhanced water flux compared to traditional reverse osmosis membranes prepared by interfacial polymerization. Additionally, the well-controlled structures achieved by mLbL deposition further lead to improved antifouling performance.

Retrotransposon reverse-transcriptase-mediated repair of chromosomal breaks

The abundance of short and long interspersed nuclear sequences (SINEs and LINEs) and pseudogenes in eukaryotic genomes indicates that reverse transcriptase (RT)-mediated phenomena are important in genome evolution. However, the mechanisms involved in their spread are largely unknown. We have developed a selection system in the yeast Saccharomyces cerevisiae to test whether RT-mediated events could be linked to the repair of double-strand breaks (DSBs). Here we show that DSBs can be fixed by the insertion of complementary DNAs at the break site. In the presence of functional RT (from human L1, yeast Tyl or Crithidia CRE1), and in the absence of homologous recombination, an HO endonuclease-induced DSB at the mating type (MAT) locus is the primary site at which a marked cDNA is observed among surviving cells. The structure and junctional sequences of these insertions suggest that repair occurs primarily by non-homologous recombination. Our data support a role for endogenous retroelements in the repair of chromosomal breaks.

Crystal structure of LexA: a conformational switch for regulation of self-cleavage

LexA repressor undergoes a self-cleavage reaction. In vivo, this reaction requires an activated form of RecA, but it occurs spontaneously in vitro at high pH. Accordingly, LexA must both allow self-cleavage and yet prevent this reaction in the absence of a stimulus. We have solved the crystal structures of several mutant forms of LexA. Strikingly, two distinct conformations are observed, one compatible with cleavage, and the other in which the cleavage site is approximately 20 A from the catalytic center. Our analysis provides insight into the structural and energetic features that modulate the interconversion between these two forms and hence the rate of the self-cleavage reaction. We suggest RecA activates the self-cleavage of LexA and related proteins through selective stabilization of the cleavable conformation.

Isolation and characterization of a thermophilic lipase from bacillus thermoleovorans ID-1

A thermophilic microorganism, Bacillus thermoleovorans ID-1, isolated from hot springs in Indonesia, showed extracellular lipase activity and high growth rates on lipid substrates at elevated temperatures. On olive oil (1.5%, w/v) as the sole carbon source, the isolate ID-1 grew very rapidly at 65 degrees C with its specific growth rate (2.50 h(-1)) and its lipase activity reached the maximum value of 520 U l(-1) during the late exponential phase and then decreased. In addition to this, isolate ID-1 could grow on a variety of lipid substrates such as oils (olive oil, soybean oil and mineral oil), triglycerides (triolein, tributyrin) and emulsifiers (Tween 20, 40). The excreted lipase of ID-1 was purified 223-fold to homogeneity by ammonium sulfate precipitation, DEAE-Sephacel ion-exchange chromatography and Sephacryl S-200 gel filtration chromatography. As a result, the relative molecular mass of the lipase was determined to be 34 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme showed optimal activity at 70-75 degrees C and pH 7.5 and exhibited 50% of its original activity after 1 h incubation at 60 degrees C and 30 min at 70 degrees C and its catalytic function was activated in the presence of Ca(2+) or Zn(2+).

In-vitro and in-vivo anti-inflammatory effect of oxyresveratrol from Morus alba L

The antioxidative effects of mulberroside A and oxyresveratrol obtained from Mori Cortex were examined. Mulberroside A and oxyresveratrol showed an inhibitory effect against FeSO4/H2O2-induced lipid peroxidation in rat microsomes and a scavenging effect on 1,1-diphenyl-2-picrylhydrazyl radical. The anti-inflammatory effects of mulberroside A and oxyresveratrol using the carrageenin-induced model of inflammation were investigated in rats. Mulberroside A and oxyresveratrol significantly reduced paw edema. To investigate the mechanism of the anti-inflammatory action of these compounds, we examined the effects of oxyresveratrol on lipopolysaccharide (LPS)-induced responses in murine macrophage cell line RAW 264.7. Exposure of LPS-stimulated cells to oxyresveratrol inhibited nitrite accumulation in the culture medium. Oxyresveratrol also inhibited the LPS-stimulated increase of inducible nitric oxide synthase (iNOS) expression in a concentration-dependent manner; however, it had little effect on iNOS enzyme activity, suggesting that the inhibitory activity of oxyresveratrol is mainly due to the inhibition of iNOS expression rather than iNOS enzyme activity. Oxyresveratrol significantly inhibited LPS-evoked nuclear translocation of NF-kB and cyclooxygenase-2 (COX-2) activity in RAW 264.7 cells. The results suggest that the anti-inflammatory properties of oxyresveratrol might be correlated with inhibition of the iNOS expression through down-regulation of NF-kB binding activity and significant inhibition of COX-2 activity.

Mutation in ATG5 reduces autophagy and leads to ataxia with developmental delay

Autophagy is required for the homeostasis of cellular material and is proposed to be involved in many aspects of health. Defects in the autophagy pathway have been observed in neurodegenerative disorders; however, no genetically-inherited pathogenic mutations in any of the core autophagy-related (ATG) genes have been reported in human patients to date. We identified a homozygous missense mutation, changing a conserved amino acid, in ATG5 in two siblings with congenital ataxia, mental retardation, and developmental delay. The subjects' cells display a decrease in autophagy flux and defects in conjugation of ATG12 to ATG5. The homologous mutation in yeast demonstrates a 30-50% reduction of induced autophagy. Flies in which Atg5 is substituted with the mutant human ATG5 exhibit severe movement disorder, in contrast to flies expressing the wild-type human protein. Our results demonstrate the critical role of autophagy in preventing neurological diseases and maintaining neuronal health.

DOI:http://dx.doi.org/10.7554/eLife.12245.001

Ataxia is a rare disease that affects balance and co-ordination, leading to difficulties in walking and other movements. The disease mostly affects adults, but some children are born with it and they often have additional cognitive and developmental problems. Mutations in at least 60 genes are known to be able to cause ataxia, but it is thought that there are still more to be found.

Kim, Sandford et al. studied two siblings with the childhood form of ataxia and found that they both had a mutation in a gene called ATG5. The protein produced by the mutant ATG5 gene was less able to interact with another protein called ATG12. Furthermore, the cells of both children had defects in a process called autophagy – which destroys old and faulty proteins to prevent them accumulating and causing damage to the cell.

Next, Kim, Sandford et al. examined the effect of this mutation in baker’s yeast cells. Cells with a mutation in the yeast equivalent of human ATG5 had lower levels of autophagy than normal cells. Further experiments used fruit flies that lacked fly Atg5, which were unable to fly or walk properly. Inserting the normal form of human ATG5 into the flies restored normal movement, but the mutant form of the gene had less of an effect.

These findings suggest that a mutation in ATG5 can be responsible for the symptoms of childhood ataxia. Kim, Sandford et al. think that other people with severe ataxia may have mutations in genes involved in autophagy. Therefore, the next step is to study autophagy in cells from many other ataxia patients.

DOI:http://dx.doi.org/10.7554/eLife.12245.002

Insulin-like growth factors regulate neuronal differentiation and survival

Insulin-like growth factor I (IGF-I) and IGF-II are potent trophic factors for motor and sensory neurons and glial cells. The actions of IGF-I and IGF-II are mediated via the IGF-I receptor (IGF-IR). IGF:IGF-IR binding activates distinct signaling cascades, which in turn mediate the trophic effects of the IGFs. We discuss three main IGF coupled events: growth cone motility, long-term neurite outgrowth, and neuroprotection. Our data suggest that IGF-I enhances growth cone motility by promoting reorganization of actin and activation of focal adhesion proteins via the phosphatidylinositol-3 kinase (Pl-3K) pathway. Long-term treatment with IGF-I activates the mitogen-activated protein (MAP) kinase cascade and promotes neurite outgrowth. A separable, but likely linked, action of the IGFs via Pl-3K is protection of neurons from apoptosis. These pleotrophic effects of IGFs suggest that this family of growth factors may have potential clinical utility in the treatment of neurological disorders.

Sex cord-stromal and steroid cell tumors of the ovary

Gonadal cell types that derive from the coelomic epithelium (sex cords) or mesenchymal cells of the embryonic gonads include granulosa cells, theca cells, fibroblasts, Leydig cells, and Sertoli cells. Ovarian tumors of these cell types are called sex cord-stromal tumors. This group of tumors represents approximately 8% of ovarian neoplasms and affects all age groups. The more common types are granulosa cell tumors (GCTs), fibrothecomas, and Sertoli-Leydig cell tumors. Sex cord-stromal tumors are of interest partly because of their hormonal effects, which are rare for other ovarian neoplasms. These effects include estrogenic effects (pseudoprecocious puberty, endometrial bleeding, endometrial hyperplasia and carcinoma) and virilization. The variety of gross appearances of these tumors, ranging from large multicystic masses to small solid masses, would appear to preclude a specific radiologic diagnosis. However, in many patients, both clinical and radiologic clues can suggest the diagnosis, including predominantly fibrous content at ultrasound or magnetic resonance imaging (fibrothecoma), large hemorrhagic multicystic mass in a child with pseudoprecocious puberty (juvenile GCT), and associated syndromes such as Peutz-Jeghers syndrome (sex cord tumor with annular tubules) or Ollier disease and Maffucci syndrome (juvenile GCT).

Hyperosmotic stress stimulates promoter activity and regulates cellular utilization of the serum- and glucocorticoid-inducible protein kinase (Sgk) by a p38 MAPK-dependent pathway

We have established that the serum- and glucocorticoid-inducible protein kinase (Sgk) is a new component of the hyperosmotic stress response. Treatment of NMuMg mammary epithelial cells with the organic osmolyte, sorbitol, caused the stable accumulation of Sgk transcripts and protein after an approximately 4-h lag. Transient transfection of a series of sgk-CAT reporter plasmids containing either 5' deletions or continuous 6-base pair substitutions identified a hyperosmotic stress-regulated element that is GC-rich and is necessary for the sorbitol stimulation of sgk gene promoter activity. Gel shift analysis identified four major DNA-protein complexes in the hyperosmotic stress-regulated element that, by competition with excess consensus wild type and mutant oligonucleotides and by antibody supershifts, contains the Sp1 transcription factor. Several lines of evidence suggest that the p38 MAPK signaling pathway mediates the hyperosmotic stress stimulation of sgk gene expression. Treatment with pharmacological inhibitors of p38 MAPK or with a dominant negative form of MKK3, an upstream regulator of p38 MAPK, significantly reduced or ablated the sorbitol induction of sgk promoter activity or protein production. Using an in vitro peptide transphosphorylation assay, sorbitol treatment activates either endogenous or exogenous Sgk that is localized to the cytoplasmic compartment. Thus, we propose that the stimulated expression of enzymatically active Sgk after sorbitol treatment is a newly defined component of the p38 MAPK-mediated response to hyperosmotic stress.

MR imaging of the male and female urethra

Conventional radiographic contrast material-enhanced studies (eg, retrograde urethrography [RUG], voiding cystourethrography [VCUG], double-balloon catheter urethrography) and ultrasonography are useful in evaluating the anatomy of the urethra but are limited in demonstrating anatomic derangement of adjacent structures. Since the anatomic details of both the urethra and periurethral tissues can be evaluated noninvasively with magnetic resonance (MR) imaging, this modality can be used as an adjunctive tool for evaluation of urethral abnormalities. In patients with congenital anomalies, MR imaging is reserved for cases of intersex anomalies or complex genitourinary anomalies, in which evaluation of internal organs is essential. MR imaging may demonstrate diverticula that are not seen on radiographic contrast-enhanced studies, including VCUG, RUG, or double-balloon catheter study. In cases of inflammation, MR imaging can demonstrate not only inflammatory infiltration around the urethra but also the presence of a periurethral abscess or sinus tract. In cases of trauma, MR imaging is helpful in assessing the presence and extent of anterior or posterior urethral injury and predicting the occurrence of complications. At MR imaging, a fistula can be seen as a direct communicating channel with an adjacent organ. In patients with urethral tumors, the major role of MR imaging is in local staging.

Insulin-like growth factor-I-mediated neurite outgrowth in vitro requires mitogen-activated protein kinase activation

Insulin-like growth factor-I (IGF-I) induces neuronal differentiation in vitro. In the present study, we examined the signaling pathway underlying IGF-I-mediated neurite outgrowth. In SH-SY5Y human neuroblastoma cells, treatment with IGF-I induced concentration- and time-dependent tyrosine phosphorylation of the type I IGF receptor (IGF-IR) and extracellular signal-regulated protein kinases (ERK) 1 and 2. These effects of IGF-I were blocked by a neutralizing antibody against IGF-IR. Whereas IGF-IR phosphorylation was observed within 1 min, maximal phosphorylation of ERKs was not reached for 30 min. Both IGF-IR and ERK phosphorylation were maintained for at least 24 h. Also, the concentration dependence of IGF-I-stimulated IGF-IR and ERK tyrosine phosphorylation paralleled that of IGF-I-mediated neurite outgrowth. We further examined the role of mitogen-activated protein kinase activation in IGF-I-stimulated neuronal differentiation using the mitogen-activated protein kinase/ERK kinase inhibitor PD98059. Whereas PD98059 had no effect on IGF-IR phosphorylation, PD98059 reduced IGF-I-mediated ERK tyrosine phosphorylation and ERK phosphorylation of the substrate Elk-1. PD98059 also produced a parallel reduction of IGF-I-stimulated neurite outgrowth. Finally, consistent with its ability to block neuronal differentiation, PD98059 inhibited IGF-I-dependent changes of GAP-43 and c-myc gene expression. Together these results suggest that activation of ERKs is essential for IGF-I-stimulated neuronal differentiation.

Diagnosis of urethral diverticula in women: value of MR imaging

OBJECTIVE

The purpose of this study was to determine the role of MR imaging in the diagnosis of urethral diverticula in women.

SUBJECTS AND METHODS

In 20 patients (mean age, 47 years), MR imaging was performed (1.5-T); unenhanced T1-weighted and T2-weighted images and contrast-enhanced T1-weighted images were obtained. MR imaging findings were compared with findings on urethrograms (including voiding cystourethrograms or double balloon catheter studies) in 16 patients, urethroscopic findings in 18, and surgical findings in 13. MR images were assessed for the presence, size, number, and location (anterior or posterior to the urethral lumen and relationship to the neck of the bladder) of diverticula, visualization of ostia, and presence of any concomitant complications. Sixteen of 20 patients had urethral diverticula: uncomplicated (simple) urethral diverticula in 13 patients; a diverticulum with a stone in one; a diverticulum with chronic granulation in one; and a diverticulum with adenocarcinoma in one. In the remaining four patients, the diagnoses included Gartner's duct cyst (one) and paraurethral cyst (one); urethras were deemed to be normal in two.

RESULTS

In 13 patients who had surgery, MR images correctly showed the presence or absence of diverticula, whereas urethrography was correct in nine (69%) and urethroscopy in 10 (77%). Compared with surgical findings (20 diverticula in 12 patients), MR images depicted 14 (70%) of 20 diverticula and urethrography and urethroscopy each depicted 11 (55%) of 20. The ostium of the diverticulum could not be identified on MR images. The use of MR contrast material did not contribute to lesion detection, but the enhanced images were superior to unenhanced images in showing granulation tissue and carcinoma, although they did not help in their differentiation.

CONCLUSION

MR imaging is accurate for showing urethral diverticula, but owing to its high cost, it should be considered only when urethroscopic or urethrographic findings are equivocal or when patients are unable to undergo these procedures and clinical findings strongly suggest a urethral diverticulum.

Calcium regulation of thin filament movement in an in vitro motility assay

The ability of calcium to regulate thin filament sliding velocity was studied in an in vitro motility assay system using cardiac troponin and tropomyosin and rhodamine-phalloidin-labeled skeletal actin and skeletal heavy meromyosin to propel the filaments. Measurements showed that both the number of thin filaments sliding and their sliding speed (Sf) were dependent on the calcium concentration in the range of pCa 5 to 9. Thin filament motility was completely inhibited only if troponin and tropomyosin were added at a concentration of 100 nM to the motility assay solution and the pCa was more than 8. The filament sliding speed was dependent on the pCa in a noncooperative fashion (Hill coefficient = 1) and reached maximum at 5 microns/s at a pCa of 5. The number of filaments moving uniformly decreased from > 90% at pCa 5-6 to near zero in less than 1 pCa unit. This behavior may be explained by a hypothesis in which the regulatory proteins control the number of cross-bridge heads interacting with the thin filaments rather than the rate at which they individually hydrolyze ATP or translocate the thin filaments.

Tyrosine phosphorylation of paxillin and focal adhesion kinase during insulin-like growth factor-I-stimulated lamellipodial advance

In the current studies, we examined whether focal adhesion kinase (FAK) and paxillin play a role in insulin-like growth factor-I (IGF-I)-stimulated morphological changes in neuronal cells. In SH-SY5Y human neuroblastoma cells, 10 nM IGF-I enhanced the extension of lamellipodia within 30 min. Scanning electron microscopy and staining with rhodamine-phalloidin showed that these lamellipodia displayed ruffles, filopodia, and a distinct meshwork of actin filaments. Immunofluorescent staining identified focal concentrations of FAK, paxillin, and phosphotyrosine within the lamellipodia. Immunoprecipitation experiments revealed that FAK and paxillin are tyrosine-phosphorylated during IGF-I-stimulated lamellipodial extension. Maximal phosphorylation of FAK and paxillin was observed 15-30 min after the addition of 10 nM IGF-I, whereas maximal IGF-I receptor phosphorylation occurred within 5 min. FAK, paxillin, and IGF-I receptor tyrosine phosphorylation had similar concentration-response curves and were inhibited by the receptor blocking antibody alphaIR-3. These results indicate that FAK and paxillin are tyrosine-phosphorylated during IGF-I-stimulated lamellipodial advance and suggest that the tyrosine phosphorylation of these two proteins helps mediate IGF-I-stimulated cell and growth cone motility. These responses contrast directly with recent reports showing insulin-stimulated dephosphorylation of FAK and paxillin.

Fabrication of nanostructures of polyethylene glycol for applications to protein adsorption and cell adhesion

A simple method was developed to fabricate polyethylene glycol (PEG) nanostructures using capillary lithography mediated by ultraviolet (UV) exposure. Acrylate-containing PEG monomers, such as PEG dimethacrylate (PEG-DMA, MW = 330), were photo-cross-linked under UV exposure to generate patterned structures. In comparison to unpatterned PEG films, hydrophobicity of PEG nanostructure modified surfaces was significantly enhanced. This could be attributed to trapped air in the nanostructures as supported by water contact angle measurements. Proteins (fibronectin, immunoglobulin, and albumin) and cells (fibroblasts and P19 EC cells) were examined on the modified surfaces to test for the level of protein adsorption and cell adhesion. It was found that proteins and cells preferred to adhere on nanostructured PEG surfaces in comparison to unpatterned PEG films; however, this level of adhesion was significantly lower than that of glass controls. These results suggest that capillary lithography can be used to fabricate PEG nanostructures capable of modifying protein and cell adhesive properties of surfaces.

Effects of reactive oxygen species on proliferation of Chinese hamster lung fibroblast (V79) cells

Reactive oxygen species (ROS) have emerged as important signaling molecules in the regulation of various cellular processes. In our study, we investigated the effect of a wide range of ROS on Chinese hamster lung fibroblast (V79) cell proliferation. Treatment with H2O2 (100 microM), superoxide anion (generated by 1 mM xanthine and 1 mU/ml xanthine oxidase), menadione, and phenazine methosulfate increased the cell proliferation by approximately 50%. Moreover, a similar result was observed after partial inhibition of superoxide dismutase (SOD) and glutathione peroxidase. This upregulation of cell proliferation was suppressed by pretreatment with hydroxyl radical scavengers and iron chelating agents. In addition to ROS, treatment with exogenous catalase and SOD mimic (MnTMPyP) suppressed the normal cell proliferation. Short-term exposure of the cells to 100 microM H2O2 was sufficient to induce proliferation, which indicated that activation of the signaling pathway is important as an early event. Accordingly, we assessed the ability of H2O2 to activate mitogen-activated protein kinases (MAPK). Jun-N-terminal kinase (JNK) and p38 MAPK were both rapidly and transiently activated by 100 microM H2O2, with maximal activation 30 min after treatment. However, the activity of extracellular signal-regulated kinase (ERK) was not changed. Pretreatment with SB203580 and SB202190, specific inhibitors of p38 MAPK, reduced the cell proliferation induced by H2O2. The activation of both JNK and p38 MAPK was also suppressed by pretreatment with hydroxyl radical scavenger and iron chelating agents. Our results suggest that the trace metal-driven Fenton reaction is a central mechanism that underlies cell proliferation and MAPK activation.

Dimerization of a specific DNA-binding protein on the DNA

Many specific DNA-binding proteins bind to sites with dyad symmetry, and the bound form of the protein is a dimer. For some proteins, dimers form in solution and bind to DNA. LexA repressor of Escherichia coli has been used to test an alternative binding model in which two monomers bind sequentially. This model predicts that a repressor monomer should bind with high specificity to an isolated operator half-site. Monomer binding to a half-site was observed. A second monomer bound to an intact operator far more tightly than the first monomer; this cooperativity arose from protein-protein contacts.

The diabetic foot ulcer

BACKGROUND

Diabetic foot ulcers are associated with significant morbidity and mortality and can subsequently lead to hospitalisation and lower limb amputation if not recognised and treated in a timely manner.

OBJECTIVE

The aim of this article is to review the current evidence for preventing and managing diabetic foot ulcers, with the aim to increase clinicians' confidence in assessing and treating these complex medical presentations.

DISCUSSION

All patients with diabetes should have an annual foot review by a general practitioner or podiatrist. A three-monthly foot review is recommended for any patient with a history of a diabetic foot infection. Assessment involves identification of risk factors including peripheral neuropathy and peripheral vascular disease, and examination of ulceration if present. It is essential to identify patients with diabetes who are 'at risk' of ulceration, assess for any early signs of skin breakdown, initiate appropriate management to prevent progression and refer the patient if indicated.