The sperm-specific proteins of the edible oyster (European flat oyster (Ostrea edulis)) are products of proteolytic processing

Extraction of sperm proteins from the bivalve mollusc Ostrea edulis shows them to contain a normal complement of core histones, together with three sperm-specific proteins, OE1 and OE2, plus the shorter OE3, which shows substantial microheterogeneity. OE1 and OE2 have a very similar amino acid composition, cyanogen bromide (CNBr) cleavage yields products of identical size and possesses a trypsin-resistant core peptide, together indicating that they are closely homologous histone H1-like proteins. Western blotting shows that OE1 and OE2 are closely related to the histone H1-like protein PL-II* of Mytilus trossulus. The amino acid composition of OE3 shows it to be a protamine-like PL-IV type protein. Edman degradation of a CNBr peptide from OE2 gave the sequence (M)KAAFAKGLKSGALVRPKGS-which has 85% identity to a sequence located towards the C-terminal end of the globular domain of the PL-II* protein of M. trossulus. An O. edulis sperm cDNA library yielded a clone of 428 bp. A genomic clone including an open reading frame (ORF) of 750 bp was isolated by PCR amplification from genomic DNA. Hypothetical translation showed the ORF to encode OE1 (or OE2) immediately followed by OE3, separated by a proteolytic processing site. This arrangement (a two-protein ORF) is also found in M. trossulus and Ensis minor.     

Two distinct steps of Bak regulation during apoptotic stress signaling: different roles of MEKK1 and JNK1

Stress-activated protein (SAP) kinases and the mitochondrial pro-apoptotic Bcl-2 protein Bak are important regulators of apoptosis. Reduced expression of Bak increases cellular resistance to the anticancer agent cisplatin, and we report here that mouse embryo fibroblasts deficient in the SAP kinase jnk1 are highly resistant to apoptosis induced by cisplatin. When human melanoma cells were treated with cisplatin, Bak function was found to be regulated in two distinct steps by two SAP kinases, MEKK1 and JNK1. The first of these steps involves MEKK1-controlled conformational activation of Bak. The second step leads to formation of 80-170 kDa Bak complexes correlating with apoptosis, and is controlled by JNK1. Inhibition of MEKK1 blocked the initial Bak conformational activation but did not block JNK1 activation, and deficiency in, or inhibition of, JNK1 did not prevent conformational activation of Bak. Furthermore, inducible expression of a constitutively active form of MEKK1 led to Bak conformational activation, but not to 80-170 kDa complexes. Consequently, apoptosis was delayed unless JNK was exogenously stimulated, indicating that Bak conformational activation is not necessarily an apoptotic marker. The two-step regulation of Bak revealed here may be important for tight control of mitochondrial factor release and apoptosis.     

Using an evolutionary algorithm to determine the parameters of a biologically inspired model of head direction cells

A biologically inspired model of head direction cells is presented and tested on a small mobile robot. Head direction cells (discovered in the brain of rats in 1984) encode the head orientation of their host irrespective of the host’s location in the environment. The head direction system thus acts as a biological compass (though not a magnetic one) for its host. Head direction cells are influenced in different ways by idiothetic (host-centred) and allothetic (not host-centred) cues. The model presented here uses the visual, vestibular and kinesthetic inputs that are simulated by robot sensors. Real robot-sensor data has been used in order to train the model’s artificial neural network connections. The main contribution of this paper lies in the use of an evolutionary algorithm in order to determine the values of parameters that determine the behaviour of the model. More importantly, the objective function of the evolutionary strategy used takes into consideration quantitative biological observations reported in the literature.     

Clinical significance of FAK expression in human neoplasia

Focal Adhesion Kinase is a 119-121 kDa nonreceptor protein kinase widely expressed in various tissues and cell types. Several studies showed that FAK plays an important role in integrin signaling. Once activated by integrin and non-integrin stimuli, it binds and activates several other molecules, such as Src, p130Cas, Grb2, PI3K and paxillin, thus promoting signaling transduction. In normal cells FAK activity is under constant regulation by mechanisms such as gene amplification, alternative splicing and action of phosphatases. On the contrary, in vitro studies showed that in transformed cells unopposed FAK signaling promoted cancer cells' malignant characteristics. FAK was held responsible for cancer cells' uninhibited proliferation, protection from apoptosis, invasion, migration, adhesion and spreading, as well as tumor angiogenesis. Several in vivo studies supported the above observations and further correlated FAK expression with various clinicopathological parameters of several types of human malignancies. The purpose of this article is a comprehensive review of the existing data on FAK expression and signaling and their clinical significance in human malignancy.     

Recovery of active ribosomal complexes from cellulose nitrate membranes

The ternary Ac-[3H]Phe-tRNA-poly(U)-ribosome complex (complex C) [D. L. Kalpaxis, D.A. Theocharis, and C. Coutsogeorgopoulos (1986) Eur. J. Biochem. 154, 267-271] was used in model experiments aiming at the purification of this complex via adsorption on cellulose nitrate membranes and then desorbing the complex back into solution. The desorption was carried out at pH 7.2 in the presence of the nonionic detergent Zwittergent (ZW). The activity status of complex C was assessed with the aid of the puromycin reaction which characterizes ribosomal peptidyltransferase as part of complex C. The optimal conditions for desorbing complex C were 5 degrees C and a buffered solution containing 0.1% ZW. The kinetic constants of peptidyltransferase in the adsorbed state were kcat = 2.0 min-1, Ks = 0.4 mM. In the desorbed state, in solution, kcat = 3.4 min-1 and Ks = 0.3 mM. The method promises to be suitable for the rapid purification of ribosomal complexes containing mRNA and aminoacyl-tRNA.     

The role of heparins and nano-heparins as therapeutic tool in breast cancer

Glycosaminoglycans are integral part of the dynamic extracellular matrix (ECM) network that control crucial biochemical and biomechanical signals required for tissue morphogenesis, differentiation, homeostasis and cancer development. Breast cancer cells communicate with stromal ones to modulate ECM mainly through release of soluble effectors during cancer progression. The intracellular cross-talk between cell surface receptors and estrogen receptors is important for the regulation of breast cancer cell properties and production of ECM molecules. In turn, reorganized ECM-cell surface interface modulates signaling cascades, which regulate almost all aspects of breast cell behavior. Heparan sulfate chains present on cell surface and matrix proteoglycans are involved in regulation of breast cancer functions since they are capable of binding numerous matrix molecules, growth factors and inflammatory mediators thus modulating their signaling. In addition to its anticoagulant activity, there is accumulating evidence highlighting various anticancer activities of heparin and nano-heparin derivatives in numerous types of cancer. Importantly, heparin derivatives significantly reduce breast cancer cell proliferation and metastasis in vitro and in vivo models as well as regulates the expression profile of major ECM macromolecules, providing strong evidence for therapeutic targeting. Nano-formulations of the glycosaminoglycan heparin are possibly novel tools for targeting tumor microenvironment. In this review, the role of heparan sulfate/heparin and its nano-formulations in breast cancer biology are presented and discussed in terms of future pharmacological targeting.     

A randomised, blinded, placebo-controlled trial in dementia patients continuing or stopping neuroleptics (the DART-AD trial)

Background

There have been increasing concerns regarding the safety and efficacy of neuroleptics in people with dementia, but there are very few long-term trials to inform clinical practice. The aim of this study was to determine the impact of long-term treatment with neuroleptic agents upon global cognitive decline and neuropsychiatric symptoms in patients with Alzheimer disease.

Methods and Findings

Design: Randomised, blinded, placebo-controlled parallel two-group treatment discontinuation trial.Setting: Oxfordshire, Newcastle and Gateshead, London and Edinburgh, United Kingdom.Participants: Patients currently prescribed the neuroleptics thioridazine, chlorpromazine, haloperidol trifluoperazine or risperidone for behavioural or psychiatric disturbance in dementia for at least 3 mo.Interventions: Continue neuroleptic treatment for 12 mo or switch to an identical placebo.Outcome measures: Primary outcome was total Severe Impairment Battery (SIB) score. Neuropsychiatric symptoms were evaluated with the Neuropsychiatric Inventory (NPI).Results: 165 patients were randomised (83 to continue treatment and 82 to placebo, i.e., discontinue treatment), of whom 128 (78%) commenced treatment (64 continue/64 placebo). Of those, 26 were lost to follow-up (13 per arm), resulting in 51 patients per arm analysed for the primary outcome. There was no significant difference between the continue treatment and placebo groups in the estimated mean change in SIB scores between baseline and 6 mo; estimated mean difference in deterioration (favouring placebo) −0.4 (95% confidence interval [CI] −6.4 to 5.5), adjusted for baseline value (p = 0.9). For neuropsychiatric symptoms, there was no significant difference between the continue treatment and placebo groups (n = 56 and 53, respectively) in the estimated mean change in NPI scores between baseline and 6 mo; estimated mean difference in deterioration (favouring continue treatment) −2.4 (95% CI −8.2 to 3.5), adjusted for baseline value (p = 0.4). Both results became more pronounced at 12 mo. There was some evidence to suggest that those patients with initial NPI ≥ 15 benefited on neuropsychiatric symptoms from continuing treatment.

Conclusions

For most patients with AD, withdrawal of neuroleptics had no overall detrimental effect on functional and cognitive status. Neuroleptics may have some value in the maintenance treatment of more severe neuropsychiatric symptoms, but this benefit must be weighed against the side effects of therapy.Trial registration: Cochrane Central Registry of Controlled Trials/National Research Register (#ISRCTN33368770).