Targeted melanoma imaging and therapy with radiolabeled alpha-melanocyte stimulating hormone peptide analogues

Radiolabeled alpha-melanocyte stimulating hormone (a-MSH) analogues have been used to define the expression, affinity and function of the melanocortin-1 receptor (MC1-R). The MC1-R is one of a family of five G-protein linker receptors, which is primarily involved in regulation of skin pigmentation. Over-expression of the MC1-R on melanoma tumor cells has made it an attractive target for the development of a-MSH peptide based imaging and therapeutic agents. Initially, the native a-MSH peptide was radiolabeled directly, but it suffered from low specific activity and poor stability. The addition of non-natural amino acids yielded a-MSH analogues with greater MC-1R affinity and stability. Furthermore, peptide cyclization via disulfide and lactam bond formation as well as site-specific metal coordination resulted in additional gains in receptor affinity and peptide stability in vitro and in vivo. Radiochemical stability of the a-MSH analogues was improved through the conjugation of metal chelators to the peptide's N-terminus or lysine residues for radionuclide coordination. In vitro cell binding studies demonstrated that the radiolabeled a-MSH analogues had low to subnanomolar affinities for the MC1-R. Biodistribution and imaging studies in the B16 mouse melanoma modeled showed rapid tumor uptake of the radiolabeled peptides, with the cyclic peptides demonstrating prolonged tumor retention. Cyclic a-MSH analogues labeled with beta and alpha emitting radionuclides demonstrated melanoma therapeutic efficacy in the B16 melanoma mouse model. Strong pre-clinical imaging and therapy data highlight the clinical potential use of radiolabeled a-MSH peptides for melanoma imaging and treatment of disseminated disease.

Iron stores and cerebral veins in MS studied by susceptibility weighted imaging

AIM

In this paper, we seek to determine whether the iron deposition as seen by susceptibility weighted imaging (SWI) in the basal ganglia and thalamus of patients with multiple sclerosis is greater than the iron content measured in normal subjects (individuals unaffected by multiple sclerosis). As increased iron content may result from increased venous pressure, such information would add credence to the concept of Zamboni et al (1) that MS is caused by chronic cerebrospinal venous insufficiency.

METHODS

Fourteen MS patients were recruited for this study with a mean age of 38 years ranging from 19 to 66 year-old. A velocity compensated 3D gradient echo sequence was used to generate SW images with a high sensitivity to iron content. We evaluated iron in the following structures: substantia nigra, red nucleus, globus pallidus, putamen, caudate nucleus, thalamus and pulvinar thalamus. Each structure was broken into two parts, a high iron content region and a low iron content region. The measured values were compared to previously established baseline iron content in these structures as a function of age.

RESULTS

Twelve of fourteen patients had an increase in iron above normal levels and with a particular pattern of iron deposition in the medial venous drainage system that was associated with the confluence of the veins draining that structure.

CONCLUSION

Iron may serve as a biomarker of venous vascular damage in multiple sclerosis. The backward iron accumulation pattern seen in the basal ganglia and thalamus of most MS patients is consistent with the hypothesis of venous hypertension.

Dimerization of CPAP orchestrates centrosome cohesion plasticity

Centrosome cohesion and segregation are accurately regulated to prevent an aberrant separation of duplicated centrosomes and to ensure the correct formation of bipolar spindles by a tight coupling with cell cycle machinery. CPAP is a centrosome protein with five coiled-coil domains and plays an important role in the control of brain size in autosomal recessive primary microcephaly. Previous studies showed that CPAP interacts with tubulin and controls centriole length. Here, we reported that CPAP forms a homodimer during interphase, and the fifth coiled-coil domain of CPAP is required for its dimerization. Moreover, this self-interaction is required for maintaining centrosome cohesion and preventing the centrosome from splitting before the G(2)/M phase. Our biochemical studies show that CPAP forms homodimers in vivo. In addition, both monomeric and dimeric CPAP are required for accurate cell division, suggesting that the temporal dynamics of CPAP homodimerization is tightly regulated during the cell cycle. Significantly, our results provide evidence that CPAP is phosphorylated during mitosis, and this phosphorylation releases its intermolecular interaction. Taken together, these results suggest that cell cycle-regulated phosphorylation orchestrates the dynamics of CPAP molecular interaction and centrosome splitting to ensure genomic stability in cell division.

[Expression of human triggering receptor expressed on myeloid cells 1 in peripheral blood mononuclear cells of patients with acute obstructive suppurative cholangitis]

OBJECTIVE

To investigate the expression pattern of human triggering receptor expressed on myeloid cells 1 (TREM-1) mRNA in peripheral blood mononuclear cells and its clinical significance in acute obstructive suppurative cholangitis (AOSC).

METHODS

Peripheral blood mononuclear cells were collected from 36 patients with AOSC and 40 healthy adults. TREM-1 mRNA was determined by semi-quantitative RT-PCR, and TREM-1 protein by immunocytochemistry. Enzyme-linked immunosorbent assay (TNF-alpha) was used to detect the level of tumor necrosis factor-alpha (TNF-alpha), and immunoturbidimetry employed to detect C reactive protein.

RESULTS

The expression of TREM-1 mRNA relative to beta-actin was 1.007-/+0.252 in patients with AOSC, significantly higher than that in the healthy adults (0.457-/+0.053, P<0.05). The two groups also showed significantly different TREM protein expression (P<0.01). The AOSC patients exhibited significantly higher levels of TNF-alpha and C reactive protein than the healthy adults (P<0.01).

CONCLUSION

The expression of human TREM-1 in peripheral blood mononuclear cells is up-regulated obviously in early stage of AOSC, probably suggesting an important role of TREM-1 in the development of AOSC.

[Subcutaneous implantation of embryonic skin cells to construct a model of hair development in nude mice]

OBJECTIVE

To observe the hair development after subcutaneous implantation of embryonic skin cells in nude mice, and construct a model of hair development.

METHODS

Dermal and epidermal cells isolated from embryonic mouse skin were mixed at a given ratio and injected subcutaneously in nude mice, and hair formation after the implantation was observed under a microscope.

RESULTS

Formation of the hair follicles and fibers under the skin of the recipient nude mice and emergence of the hair shaft were observed microscopically.

CONCLUSION

Embryonic skin cells be used to construct a complete model of hair development after implantation in vivo.

[Effects of different parts of the follicle-unit grafts subjected to controlled injury]

OBJECTIVE

To study the shaft elongation and morphological changes of follicle-unit (FUs) grafts subjected to controlled injury in different parts.

METHODS

Human FUs were isolated by microdissection under a dissecting microscope. The single hair of anagen FUs were randomly divided into A, B and C groups, and A and B groups were subjected to controlled injury with microsurgery imposed to the dermal papilla and the bulge of FUs, respectively, with C as the control group without any treatment. HE staining was used to detect the histological changes of the cells, and organ culture for 10 days was conducted to observe the morphological changes and elongation of FUs.

RESULTS

There were no histological or morphological changes in A, B and C groups. The average elongation of hair shaft was 1.293-/+0.245, 2.116-/+0.423 and 2.235-/+0.379 mm, respectively. There were significant differences between groups A and B (P<0.05) and between groups A and C (P<0.05). No significant difference was found between groups B and C (P>0.05).

CONCLUSION

Damage of the dermal papilla should be avoided in hair transplantation surgery.

Self-assembly of nanocomponents into composite structures: derivation and simulation of Langevin equations

The kinetics of the self-assembly of nanocomponents into a virus, nanocapsule, or other composite structure is analyzed via a multiscale approach. The objective is to achieve predictability and to preserve key atomic-scale features that underlie the formation and stability of the composite structures. We start with an all-atom description, the Liouville equation, and the order parameters characterizing nanoscale features of the system. An equation of Smoluchowski type for the stochastic dynamics of the order parameters is derived from the Liouville equation via a multiscale perturbation technique. The self-assembly of composite structures from nanocomponents with internal atomic structure is analyzed and growth rates are derived. Applications include the assembly of a viral capsid from capsomers, a ribosome from its major subunits, and composite materials from fibers and nanoparticles. Our approach overcomes errors in other coarse-graining methods, which neglect the influence of the nanoscale configuration on the atomistic fluctuations. We account for the effect of order parameters on the statistics of the atomistic fluctuations, which contribute to the entropic and average forces driving order parameter evolution. This approach enables an efficient algorithm for computer simulation of self-assembly, whereas other methods severely limit the timestep due to the separation of diffusional and complexing characteristic times. Given that our approach does not require recalibration with each new application, it provides a way to estimate assembly rates and thereby facilitate the discovery of self-assembly pathways and kinetic dead-end structures.

Comparative analysis of five varieties in Perilla frutescens (L.) Britton by 45S rDNA FISH and 5S rDNA sequences

In this study, the relationships of five varieties in Perilla frutescens (L.) Britton were analyzed. All the varieties showed the same chromosome number 2n = 40, and the banding patterns of PI-DAPI staining and the FISH results of 45S rDNA probe were on the same site of the chromosome pair. The 5S rRNA gene spacers were ranged from 413 bp in P. frutescens var. purpurascens and 408 bp in var. frutescens. The varieties analyzed here were clustered into two clades according to the phylogenetic analysis. The sequence identity of 96% between var. auriculato-dentata and var. arguta suggested they could be considered the same variety.

Assessment of self-reported and health-related quality of life in patients with brain tumours using a modified questionnaire

Assessment of quality of life (QoL) in patients who undergo surgery for brain tumours helps to guide surgery, reduce recurrence and minimize morbidity. This study validated a 25-item, modified QoL questionnaire based on the Medical Outcomes Survey SF-36 and the Karnofsky Performance Scale. The aims were for it to be brain tumour specific for Chinese patients, hence more sensitive, more acceptable, briefer and more easily used. A total of 431 patients with brain tumours were compared with 96 age-matched healthy controls. A surgery-related QoL curve was used to help identify a threshold satisfaction point for QoL. Physiological function, psychological function, satisfaction with medical care and self-care ability of the patients were compared pre-operatively and post-operatively. Cronbach's alpha-coefficient was 0.9521 and the correlation coefficient was 0.8685, suggesting good reliability and repeatability. With the exception of psychological function, which deteriorated, the modified QoL showed significant improvement in physiological function, satisfaction with medical care and self-care ability, and serves to stress the importance of post-operative psychological support.

RNA interference-mediated silencing of the polo-like kinase 1 gene enhances chemosensitivity to gemcitabine in pancreatic adenocarcinoma cells

Gemcitabine is the first-line chemotherapeutic agent for advanced adenocarcinoma of the pancreas; however, chemoresistance to gemcitabine remains a major cause of failure for the clinical treatment of this disease. Polo-like kinase 1 (Plk-1) is highly expressed in pancreatic cancer cell lines and pancreatic tumour tissues, and is involved in a wide variety of cell cycle processes. Nevertheless, its biological role and implication for gemcitabine resistance are not clearly defined. In this study, we used RNA-interference (RNAi)-mediated depletion of Plk-1 to determine its potential for sensitizing pancreatic tumour cells to gemcitabine. We showed that the level of Plk-1 protein was correlated significantly with gemcitabine resistance in human pancreatic adenocarcinoma cells and that overexpression of Plk-1 reduced sensitivity to gemcitabine in these cells. In addition, small interfering RNA (siRNA)-mediated knockdown of Plk-1 caused cell cycle arrest at G2/M and the reduction of cellular proliferation. More importantly, the treatment of pancreatic cancer cells with Plk-1 siRNA followed by exposure to gemcitabine dramatically decreased cell viability and increased cellular apoptosis, as compared with treatment with either agent alone. These observations indicate that down-regulation of Plk-1 expression by RNAi enhances gemcitabine sensitivity and increases gemcitabine cytotoxicity in pancreatic tumour cells. This is the first demonstration that the combination of Plk-1 gene therapy and gemcitabine chemotherapy has synergistic anti-tumour activity against pancreatic carcinoma in vitro. This combination treatment warrants further investigation as an effective therapeutic regimen for patients with resistant pancreatic cancer and other tumours.

Buried bumper syndrome: cut and leave it alone!

Buried bumper syndrome (BBS) occurs due to the overgrowth of gastric mucosa over the inner bumper of a gastrostomy tube. Various therapeutic approaches have been described for the management of BBS. However, no standardized clinical protocol deals with this complication. The authors describe their experience of dealing with BBS. Case notes of the patients undergoing percutaneous endoscopic gastrostomy (PEG) between February 2002 and December 2007 at their institute were reviewed retrospectively, and cases of BBS were analyzed. During this 71-month period, 356 PEG procedures were preformed. Seven patients with BBS were identified from the case note review (incidence of 1.97%). Attempts at endoscopic removal of the buried bumper were made but unfortunately failed. In view of the patients' associated comorbidity, the buried bumpers in these patients were left in situ, and a new PEG was inserted adjacent to the first site in 6 individuals. In 1 patient, a jejunal extension tube was inserted through the original PEG tube for feeding. No complications from the buried bumper arose in these patients during a median follow-up of 18 months (range, 1-46 months). Some patients being fed by a PEG tube are in poor general health and have significant comorbidities. They are therefore poor candidates for surgical or endoscopic removal of a buried bumper. In such patients, leaving the internal bumper in situ should be considered as a relatively safe treatment option.

A novel upstream regulator of WRKY53 transcription during leaf senescence in Arabidopsis thaliana

Arabidopsis WRKY proteins comprise a family of zinc finger-type transcription factors involved in the regulation of gene expression during pathogen defence, wounding, trichome development and senescence. To better understand the regulatory role of the senescence-related WRKY53 factor, we identified upstream regulatory factors using the yeast one-hybrid system. Among others, we identified a DNA-binding protein with a so far unknown function that contains a transcriptional activation domain and a kinase domain with similarities to HPT kinases. In vitro studies revealed that this activation domain protein (AD protein) can phosphorylate itself and that phosphorylation increases its DNA-binding activity to the WRKY53 promoter region. Using the yeast two-hybrid system, an interaction with proteins that were previously shown to bind to the WRKY53 promoter was tested. The AD protein interacted with MEKK1. The interaction with MEKK1 was confirmed in vivo by bimolecular fluorescence complementation (BiFC); however, the AD protein was not phosphorylated by MEKK1 in vitro and vice versa. This indicates that there may be competition between WRKY53 and AD protein for binding of MEKK1 at the WRKY53 promoter. Overexpression and knockout of the respective gene resulted in changes in transcription levels of WRKY53, indicating that AD protein is a positive regulator of WRKY53 expression. Expression of the AD protein gene can be induced by hydrogen peroxide treatment and reduced by jasmonic acid treatment, as previously shown for WRKY53.

Stochastic dynamics of bionanosystems: Multiscale analysis and specialized ensembles

An approach for simulating bionanosystems such as viruses and ribosomes is presented. This calibration-free approach is based on an all-atom description for bionanosystems, a universal interatomic force field, and a multiscale perspective. The supramillion-atom nature of these bionanosystems prohibits the use of a direct molecular dynamics approach for phenomena such as viral structural transitions or self-assembly that develop over milliseconds or longer. A key element of these multiscale systems is the cross-talk between, and consequent strong coupling of processes over many scales in space and time. Thus, overall nanoscale features of these systems control the relative probability of atomistic fluctuations, while the latter mediate the average forces and diffusion coefficients that induce the dynamics of these nanoscale features. This feedback loop is overlooked in typical coarse-grained methods. We elucidate the role of interscale cross-talk and overcome bionanosystem simulation difficulties with (1) automated construction of order parameters (OPs) describing suprananometer scale structural features, (2) construction of OP-dependent ensembles describing the statistical properties of atomistic variables that ultimately contribute to the entropies driving the dynamics of the OPs, and (3) the derivation of a rigorous equation for the stochastic dynamics of the OPs. As the OPs capture hydrodynamic modes in the host medium, "long-time tails" in the correlation functions yielding the generalized diffusion coefficients do not emerge. Since the atomic-scale features of the system are treated statistically, several ensembles are constructed that reflect various experimental conditions. Attention is paid to the proper use of the Gibbs hypothesized equivalence of long-time and ensemble averages to accommodate the varying experimental conditions. The theory provides a basis for a practical, quantitative bionanosystem modeling approach that preserves the cross-talk between the atomic and nanoscale features. A method for integrating information from nanotechnical experimental data in the derivation of equations of stochastic OP dynamics is also introduced.