Insights into G protein structure, function, and regulation

In multicellular organisms from Caenorhabditis elegans to Homo sapiens, the maintenance of homeostasis is dependent on the continual flow and processing of information through a complex network of cells. Moreover, in order for the organism to respond to an ever-changing environment, intercellular signals must be transduced, amplified, and ultimately converted to the appropriate physiological response. The resolution of the molecular events underlying signal response and integration forms the basis of the signal transduction field of research. An evolutionarily highly conserved group of molecules known as heterotrimeric guanine nucleotide-binding proteins (G proteins) are key determinants of the specificity and temporal characteristics of many signaling processes and are the topic of this review. Numerous hormones, neurotransmitters, chemokines, local mediators, and sensory stimuli exert their effects on cells by binding to heptahelical membrane receptors coupled to heterotrimeric G proteins. These highly specialized transducers can modulate the activity of multiple signaling pathways leading to diverse biological responses. In vivo, specific combinations of G alpha- and G beta gamma-subunits are likely required for connecting individual receptors to signaling pathways. The structural determinants of receptor-G protein-effector specificity are not completely understood and, in addition to involving interaction domains of these primary acting proteins, also require the participation of scaffolding and regulatory proteins.     

Determining the date of diagnosis – is it a simple matter? The impact of different approaches to dating diagnosis on estimates of delayed care for ovarian cancer in UK primary care

Background  

Studies of cancer incidence and early management will increasingly draw on routine electronic patient records. However, data may be incomplete or inaccurate. We developed a generalisable strategy for investigating presenting symptoms and delays in diagnosis using ovarian cancer as an example.     

Bortezomib inhibits cell-cell adhesion and cell migration and enhances epidermal growth factor receptor inhibitor-induced cell death in squamous cell cancer

The lack of cell-cell adhesion and increased migration are key characteristics of cancer cells. The loss of expression of cell adhesion components and overexpression of components critical for cell migration, such as focal adhesion kinase (FAK), correlate with poor prognosis. Because alteration of protein turnover affects the expression levels and, in turn, may influence protein function, we investigated the effects of the proteasome inhibitor bortezomib on cell adhesion and migration in oral squamous cell cancer cell lines SCC68 and SCC15. Following treatment with bortezomib, protein levels of adherens junction components such as E-cadherin were unchanged. The desmosomal linker protein desmoplakin level was increased, whereas the protein level of the desmosomal cadherin, desmoglein 2, was diminished. Reduced desmoglein 2 levels correlated with the diminished strength of mechanical cell-cell adhesion. The protein level of the epidermal growth factor receptor (EGFR) increased after proteasome inhibition and EGFR inhibition with the EGFR-specific tyrosine kinase inhibitor PKI166 was able to restore cell-cell adhesion. Furthermore, we found that the combination of PKI166 with bortezomib enhanced the rate of cell death. Although the FAK protein level was unchanged following bortezomib treatment, recruitment of FAK phosphorylated at tyrosine residue 397 to the periphery of the cell was induced. Migration was reduced following treatment with bortezomib, which could potentially be explained by a prominent but disorganized actin fiber network revealed through immunofluorescence. Collectively, our results suggest that proteasome inhibition using bortezomib affects cell adhesion and cell migration profoundly and provides a rationale for its clinical use in conjunction with an EGFR inhibitor.     

Management of first-episode pelvic inflammatory disease in primary care: results from a large UK primary care database

Background

Prompt and effective treatment of pelvic inflammatory disease (PID) may help prevent long-term complications. Many PID cases are seen in primary care but it is not known how well management follows recommended guidelines.

Aim

To estimate the incidence of first-episode PID cases seen in UK general practice, describe their management, and assess its adequacy in relation to existing guidelines.

Design of study

Cohort study.

Setting

UK general practices contributing to the General Practice Research Database (GPRD).

Method

Women aged 15 to 40 years, consulting with a first episode of PID occurring between 30 June 2003 and 30 June 2008 were identified, based on the presence of a diagnostic code. The records within 28 days either side of the diagnosis date were analysed to describe management.

Results

A total of 3797 women with a first-ever coded diagnosis of PID were identified. Incidence fell during the study period from 19.3 to 8.9/10 000 person-years. Thirty-four per cent of cases had evidence of care elsewhere, while 2064 (56%) appeared to have been managed wholly within the practice. Of these 2064 women, 34% received recommended treatment including metronidazole, and 54% had had a Chlamydia trachomatis test, but only 16% received both. Management was more likely to follow guidelines in women in their 20s, and later in the study period.

Conclusion

These analyses suggest that the management of PID in UK primary care, although improving, does not follow recommended guidelines for the majority of women. Further research is needed to understand the delivery of care in general practice and the coding of such complex syndromic conditions.     

Polyamine-polycarboxylate metal complexes with different biological effectiveness as nitric oxide scavengers. Clues for drug design

The synthesis of the Fe(III), Co(II), Mn(II), and Ru(III) complexes with two polyamine-polycarboxylate ligands, N-(2-hydroxyethyl)ethylenediamine-N, N', N'-triacetic acid (H3L1) and ethylene bisglycol tetraacetic acid (H4L2) is reported. Potentiometric studies showed that these ligands form stable complexes in aqueous solution and no metal release occurs, thus accounting for their low toxicity in cultured RAW 264.7 macrophages. X-ray characterization of the [Co(L1)](-) complex showed that binding sites are available at the metal for NO binding. Efficiency of these compounds to bind NO was studied by UV-vis spectrophotometry. Then their NO-scavenging properties were assayed in a cell-free system under physiological conditions, using S-nitroso-N-acetyl-D,L-penicillamine (SNAP) as NO source. The L1 complexes caused the most effective reduction of free NO, [Mn(L1)](-) being the most efficient. Conversely, in NOS II induced RAW 264.7 macrophages, the Ru(III) and Co(II) complexes with L2 were the most effective compounds. [Ru(L2)](-) also afforded significant protection against lipopolysaccharide-induced endotoxic shock in the mouse in vivo.     

The Temperature‐Responsive Nanoassemblies of Amphiphilic Random Copolymers Carrying Poly(siloxane) and Poly(oxyethylene) Pendant Chains

Novel amphiphilic random copolymers carrying poly(oxyethylene) and poly(siloxane) pendant chains are synthesized by atom transfer radical polymerization starting from either a fluorescent, julolidine‐based initiator, or a nonfluorescent initiator. For both copolymer systems, dynamic light scattering measurements carried out on aqueous solutions as a function of temperature reveal the occurrence of a sharp and fully reversible transition between two different self‐associative states of individual, single‐chain self‐folded nanoassemblies, so‐called unimer micelles, (D_h = 8–10 nm) and collapsed multichain aggregates (D_h = 700–1400 nm) at a critical temperature T_c. Covalently linked julolidine terminal and added ethidium bromide are separately used as fluorescent probes and both prove the temperature‐dependence of the different self‐association of the copolymers in water.     

The tolerance of gastrointestinal organs to stereotactic body radiation therapy: what do we know so far?

As stereotactic body radiation therapy (SBRT) for gastrointestinal (GI) gains popularity, there is a need to optimize doses and fractionation to minimize GI toxicity. GI organs that have classically developed radiation-induced toxicity include the liver & biliary system, small bowel, esophagus, and rectum. While the literature quantifies dose restrictions for these organs under standard fractionation, there is limited data regarding toxicity with the ablative dose schedules used in SBRT. We conducted a review of the literature to identify prospective and retrospective studies that detail GI toxicities when SBRT was employed. Based on the literature, the median SBRT dose for abdominal and thoracic tumors ranged from 24 to 60 Gy, at 5 to 25 Gy per fraction. The respective observed frequencies of grade 3 and 4 toxicities for the liver, biliary system, small bowel, and esophagus were variable among different studies. Typically, patients who suffered grade 3 and 4 toxicities were more likely to have had some form of systemic therapy as well. The effect of dose, fractionation, timing, and volume on GI toxicities has been described in the literature but more data is necessary to develop uniform treatment guidelines for SBRT.     

Applications in Bridging the Gap: A Community-Campus Partnership to Address Sexual Health Disparities Among African-American Youth in the South

Risky sexual behavior among African-American youth increases risks for sexually transmitted diseases and unintended pregnancy. This article describes a community-academic partnership to assess The 2 HYPE Abstinence Club, a program combining abstinence education with stress management and creative arts promotion for African-American youth ages 12–18. Bi-directional learning and communication systems were established to facilitate culturally relevant evaluation approaches, quality assurance in data collection, and action-based protocols for on-going improvement. Assessment tools included self-administered surveys and focus groups to gauge intervention effectiveness and perceptions regarding abstinence, sexual peer norms and intervention characteristics. Statistically significant increases in the understanding of abstinence benefits and sexual activity risks were observed and youth identified goal-setting and refusal skills as most important program components. Youth-instructor relationships and the integration of hip-hop were reasons cited for sustained participation. This assessment partnership represents a rapport with minority youth and a participatory evaluation approach adding programmatic and evidence-based value to intervention efforts.