Synthesis and biological evaluation of novel heterocyclic derivatives of combretastatin A-4

A novel series of combretastatin A-4 heterocyclic analogues was prepared by replacement of the B ring with indole, benzofurane or benzothiophene, attached at the C2 position. These compounds were evaluated for their abilities to inhibit tubulin assembly: derivative cis 3b, having a benzothiophene, showed an activity similar to those of colchicine or deoxypodophyllotoxine. The antiproliferative and antimitotic properties of cis 3b against keratinocyte cancer cell lines were also evaluated and the intracellular organization of microtubules in the cells after treatment with both stereoisomers of 3b was also determined, using confocal microscopy.     

Factors associated with inadequate colorectal cancer screening with flexible sigmoidoscopy

Background and study aim: Inadequate colorectal cancer screening wastes limited endoscopic resources. We examined patients factors associated with inadequate flexible sigmoidoscopy (FSG) screening at baseline screening and repeat screening 3–5 years later in 10 geographically-dispersed screening centers participating in the ongoing Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Methods: A total of 64,554 participants (aged 55–74) completed baseline questionnaires and underwent FSG at baseline. Of these, 39,385 participants returned for repeat screening. We used logistic regression models to assess factors that are associated with inadequate FSG (defined as a study in which the depth of insertion of FSG was <50 cm or visual inspection was limited to <90% of the mucosal surface but without detection of a polyp or mass). Results: Of 7084 (11%) participants with inadequate FSG at baseline, 6496 (91.7%) had <50 cm depth of insertion (75.3% due to patient discomfort) and 500 (7.1%) participants had adequate depth of insertion but suboptimal bowel preparation. Compared to 55–59 year age group, advancing age in 5-year increments (odds ratios (OR) from 1.08 to 1.51) and female sex (OR = 2.40; 95% confidence interval (CI): 2.27–2.54) were associated with inadequate FSG. Obesity (BMI >30 kg/m²) was associated with reduced odds (OR = 0.67; 95% CI: 0.62–0.72). Inadequate FSG screening at baseline was associated with inadequate FSG at repeat screening (OR = 6.24; 95% CI: 5.78–6.75). Conclusions: Sedation should be considered for patients with inadequate FSG or an alternative colorectal cancer screening method should be recommended.     

Ground reaction forces and impulses during a transient turning maneuver

Understanding the kinetic strategies of turning as expressed in ground reaction forces (GRFs) and impulses (GRIs) is necessary to design therapies and technologies to enable patients with ambulatory difficulties perform daily activities. Previous studies have reported data only for one step of the turn and expressed the data in terms of a global reference frame making it difficult to understand how the forces act on the body to cause a change in heading and orientation during a turn. This study is the first to report GRF and GRI data for three steps of a turn and express that data in terms of a body reference frame. Motion and GRF data were collected from 10 subjects walking at self-selected speeds along a straight path and performing 90 degrees left and right turns. During the left turn, turn initiation and apex steps were collected. During the right turn, turn termination steps were collected. GRF data were rotated to a reference frame whose origin was the body center of mass (COM) and aligned to the COM trajectory and then integrated to find the GRIs. In the medial-lateral direction, straight steps were characterized by a brief medial impulse at heel strike followed by a prolonged lateral impulse. Turn initiation and termination steps were both characterized by medial impulses spanning the entire stance phase while apex steps were characterized by a large lateral impulse. In the anterior-posterior direction, initiation steps had larger braking and smaller propulsive impulses than straight steps. Apex steps had larger propulsive impulses than straight steps, and termination steps had smaller braking and larger propulsive impulses than straight steps.     

Senescence and apoptosis in yeast mother cell-specific aging and in higher cells: a short review

It is our intention to give the reader a short overview of the relationship between apoptosis and senescence in yeast mother cell-specific aging. We are studying yeast as an aging model because we want to learn something of the basic biology of senescence and apoptosis even from a unicellular eukaryotic model system, using its unrivalled ease of genetic analysis. Consequently, we will discuss also some aspects of apoptosis in metazoa and the relevance of yeast apoptosis and aging research for cellular (Hayflick type) and organismic aging of multicellular higher organisms. In particular, we will discuss the occurrence and relevance of apoptotic phenotypes for the aging process. We want to ask the question whether apoptosis (or parts of the apoptotic process) are a possible cause of aging or vice versa and want to investigate the role of the cellular stress response system in both of these processes. Studying the current literature, it appears that little is known for sure in this field and our review will therefore be, for a large part, more like a memorandum or a program for future research.     

The role of prostaglandins in triggering the liver regeneration cascade.

Following injury or surgical resection, the liver has the remarkable ability to regenerate. Despite over 100 years of research, the trigger of the liver regeneration cascade has only recently been identified. Shear stress-induced nitric oxide (NO), released secondary to a hemodynamic event following partial hepatectomy (PHX), has been implicated as the trigger of the liver regeneration cascade. However, it is also known that prostaglandins (PGs) are released following PHX, and in response to shear stress. Therefore, it is hypothesized that PGs, released secondary to an increase in the blood flow-to-liver mass ratio following PHX, trigger the liver regeneration cascade, and that NO and PGs interact during the triggering event. An index of initiation of the liver regeneration cascade, c-fos mRNA expression 15 min after PHX, has been employed. As expected, c-fos mRNA expression increased 15 min after PHX and this increase was inhibited by the NO synthase antagonist, l-NAME. This inhibition was reversed by the NO donors, SIN-1 and SNAP, and by the PGs, PGE2 and PGI2. Also, the increase in c-fos mRNA expression was inhibited by indomethacin, a cyclooxygenase antagonist. This inhibition was also reversed by the NO donors, SIN-1 and SNAP, and by the PGs, PGE2 and PGI2. These results suggest that there is interaction between NO and PGs in triggering the liver regeneration cascade, and that in a situation where either NO or COX is inhibited, provision of excess exogenous NO or PGs can reverse the inhibition. This suggests that exogenous NO and/or PGs may play a role in potentiation of the liver regeneration cascade.     

Ubiquitination of a novel deubiquitinating enzyme requires direct binding to von Hippel-Lindau tumor suppressor protein.

von Hippel-Lindau (VHL) disease is a hereditary cancer syndrome caused by germline mutations of the VHL gene. Recent studies suggest that VHL protein (pVHL) is a component of an E3 ubiquitin ligase, but the detailed biological function of pVHL remains to be determined. To further elucidate the biological functions of pVHL, we searched pVHL-interacting proteins using yeast two-hybrid screening. A novel protein named VHL-interacting deubiquitinating enzyme 1 (VDU1) was identified as being able to directly interact with pVHL in vitro and in vivo. We have determined the full-length cDNA of this enzyme, which includes two putative subtypes. Type I consists of 942 amino acids, and type II consists of 911 amino acids with predicted molecular masses of 107 and 103 kDa, respectively. We have also cloned a mouse homologue of this enzyme. Sequence analysis reveals that this protein is conserved between human and mouse and contains the signature motifs of the ubiquitin-specific processing protease family. Enzymatic function studies demonstrate its deubiquitinating activity. We have determined that the VDU1-interacting region in pVHL is located in its beta-domain, and several naturally occurring mutations located in this domain disrupt the interaction between pVHL and VDU1 protein. Co-immunoprecipitation demonstrates that VDU1 can be recruited into the pVHL-elongin C-elongin B complex. Finally, we demonstrate that VDU1 is able to be ubiquitinated via a pVHL-dependent pathway for proteasomal degradation, and VHL mutations that disrupt the interaction between VDU1 and pVHL abrogate the ubiquitination of VDU1. Our findings indicate that VDU1, a novel ubiquitin-specific processing protease, is a downstream target for ubiquitination and degradation by pVHL E3 ligase. Targeted degradation of VDU1 by pVHL could be crucial for regulating the ubiquitin-proteasome degradation pathway.     

Neurotransmitter Specific,Cellular-Resolution Functional Brain Mapping Using Receptor Coated Nanoparticles: Assessment of the Possibility

Receptor coated resonant nanoparticles and quantum dots are proposed to provide a cellular-level resolution image of neural activities inside the brain. The functionalized nanoparticles and quantum dots in this approach will selectively bind to different neurotransmitters in the extra-synaptic regions of neurons. This allows us to detect neural activities in real time by monitoring the nanoparticles and quantum dots optically. Gold nanoparticles (GNPs) with two different geometries (sphere and rod) and quantum dots (QDs) with different sizes were studied along with three different neurotransmitters: dopamine, gamma-Aminobutyric acid (GABA), and glycine. The absorption/emission spectra of GNPs and QDs before and after binding of neurotransmitters and their corresponding receptors are reported. The results using QDs and nanorods with diameter 25nm and aspect rations larger than three were promising for the development of the proposed functional brain mapping approach.     

Patterns of DNA methylation in the normal colon vary by anatomical location,gender, and age

Alterations in DNA methylation have been proposed to create a field cancerization state in the colon, where molecular alterations that predispose cells to transformation occur in histologically normal tissue. However, our understanding of the role of DNA methylation in field cancerization is limited by an incomplete characterization of the methylation state of the normal colon. In order to determine the colon’s normal methylation state, we extracted DNA from normal colon biopsies from the rectum, sigmoid, transverse, and ascending colon and assessed the methylation status of the DNA by pyrosequencing candidate loci as well as with HumanMethylation450 arrays. We found that methylation levels of repetitive elements LINE-1 and SAT-α showed minimal variability throughout the colon in contrast to other loci. Promoter methylation of EVL was highest in the rectum and progressively lower in the proximal segments, whereas ESR1 methylation was higher in older individuals. Genome-wide methylation analysis of normal DNA revealed 8388, 82, and 93 differentially methylated loci that distinguished right from left colon, males from females, and older vs. younger individuals, respectively. Although variability in methylation between biopsies and among different colon segments was minimal for repetitive elements, analyses of specific cancer-related genes as well as a genome-wide methylation analysis demonstrated differential methylation based on colon location, individual age, and gender. These studies advance our knowledge regarding the variation of DNA methylation in the normal colon, a prerequisite for future studies aimed at understanding methylation differences indicative of a colon field effect.