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Biomedical subjects

G Brooks

Publications and source records attributed to G Brooks.

At least 19 recordsLinked to original sources
PubMed2005

Functional interactions of antiapoptotic proteins and tumor necrosis factor in the context of a replication-competent adenovirus.

Replication-selective oncolytic adenoviruses hold promise, but novel mechanisms must be identified to maximize intratumoral virus persistence, spread and therapeutic transgene-carrying capacity while maintaining safety. One of the main approaches to engineering cancer-selectivity has been to delete a viral gene that is theoretically expendable in cancer cells. Results with this approach have been mixed, however, as evidenced by controversy over Onyx-015 (E1B-55kD(-)) selectivity. We hypothesized that the functional redundancy between viral gene products might limit selectivity and/or potency with this approach. Antiviral immune inducers of apoptosis (eg TNF-alpha) have not been thoroughly investigated in previous studies. We therefore explored whether deletion of functionally redundant viral genes, E1B-19kD and E3B, both independently antagonize TNF-alpha, could lead to enhanced oncolytic potency while maintaining selectivity. Since tumors have numerous blocks in apoptotic pathways, we hypothesized that deletion of one or both gene regions would result in cancer-selectivity in the presence of TNF-alpha. We have previously shown that the E1B-19kD deletion resulted in enhanced viral spread in vitro and in immunocompetent tumor models in vivo. In contrast, the impact of E3B deletion, especially its in vitro selectivity and potency, was not thoroughly characterized, although it resulted in rapid immune-mediated viral clearance in vivo. Furthermore, previous publications indicated that double-deleted mutants have selectivity but unsatisfactory efficacy. We compared the selectivity and potency of E1B-19kD(-), E3B(-) and E1B-19kD(-)/E3B(-) mutants to wild-type adenovirus. In cancer cells, the E1B-19kD(-) mutant had superior replication, spread and cytolysis (+) or (-) TNF-alpha; deletion of both E1B-19kD and E3B was relatively deleterious. In normal cells without TNF-alpha, similar results were obtained. In contrast, all three mutants were significantly inhibited in the presence of TNF-alpha. In immunocompetent mice, all three mutants were significantly inhibited in normal tissue. In tumors, only the E1B-19kD(-) mutant demonstrated enhanced replication, spread and antitumoral efficacy. Therefore, E1B-19kD deletion and E3B retention should be incorporated in oncolytic adenoviruses for enhanced safety and efficacy. In addition, functional redundant viral genes and their biological mediators/targets need to be carefully examined for the next generation of gene-deleted oncolytic viruses.

Adenoviridae↗
PubMed2005

Launching the Tidal Model: evaluating the evidence.

Launching the Tidal Model: evaluating the evidence This paper reports on two evaluations of the Tidal Model, in the context of two separate acute admission wards, one in Birmingham (2004) and the other in Newcastle (2001), and makes recommendations concerning the criteria and type of reasoning appropriate to evaluating the evidence the two projects have generated. In the Birmingham study, results showed that in the year following the introduction of the Tidal Model, the total number of serious untoward incidents such as physical assault, violence and harassment, decreased by 57%. Nurse satisfaction with their work also improved with nurses rating the model superior to their previous way of working. Inpatient service user assessment of the overall quality of their care was also positive. These findings are then compared with the positive results of an earlier study of the Tidal Model undertaken in Newcastle in 2001. That study was criticized, however, for not showing conclusively that the positive results of the evaluation correlated with the introduction of the Tidal Model. This criticism is briefly examined in the light of both ancient (Aristotle) and modern (Charles Peirce) understandings of the nature of evidence and suggests that such criticism begs the question of the nature of proof. The paper concludes by arguing that, according to both Aristotle and the procedures of abductive reasoning advocated by Charles Peirce, inferring a positive correlation between the results of both studies and the introduction of Tidal Model is a good example of reasonable inference to the best explanation. The available evidence suggests that the results of both studies render the conclusion probable and thus 'good enough' to warrant serious consideration for implementing the Tidal Model more widely within and across Mental Health NHS Trusts.

Humans↗
PubMed2001

Pleuromutilins. Part 1. The identification of novel mutilin 14-carbamates.

A novel series of mutilin 14-carbamates has been discovered as a result of structure-activity studies on the naturally occurring antibiotic pleuromutilin (1). In particular, the 4-methoxybenzoylcarbamate, SB-222734 (15o) displays potent antibacterial activity against a number of bacterial pathogens which are resistant to currently used agents and shows enhanced metabolic stability when compared to earlier pleuromutilin derivatives. Such derivatives therefore have the potential to provide a new class of antibacterial agents for human therapy which address the threat of bacterial resistance.

Anti-Bacterial Agents↗
PubMed2001

The coronavirus infectious bronchitis virus nucleoprotein localizes to the nucleolus.

The coronavirus nucleoprotein (N) has been reported to be involved in various aspects of virus replication. We examined by confocal microscopy the subcellular localization of the avian infectious bronchitis virus N protein both in the absence and in the context of an infected cell and found that N protein localizes both to the cytoplasmic and nucleolar compartments.

Amino Acid Sequence↗
PubMed2001

Localization to the nucleolus is a common feature of coronavirus nucleoproteins, and the protein may disrupt host cell division.

The subcellular localization of transmissible gastroenteritis virus (TGEV) and mouse hepatitis virus (MHV) (group I and group II coronaviruses, respectively) nucleoproteins (N proteins) were examined by confocal microscopy. The proteins were shown to localize either to the cytoplasm alone or to the cytoplasm and a structure in the nucleus. This feature was confirmed to be the nucleolus by using specific antibodies to nucleolin, a major component of the nucleolus, and by confocal microscopy to image sections through a cell expressing N protein. These findings are consistent with our previous report for infectious bronchitis virus (group III coronavirus) (J. A. Hiscox et al., J. Virol. 75:506-512, 2001), indicating that nucleolar localization of the N protein is a common feature of the coronavirus family and is possibly of functional significance. Nucleolar localization signals were identified in the domain III region of the N protein from all three coronavirus groups, and this suggested that transport of N protein to the nucleus might be an active process. In addition, our results suggest that the N protein might function to disrupt cell division. Thus, we observed that approximately 30% of cells transfected with the N protein appeared to be undergoing cell division. The most likely explanation for this is that the N protein induced a cell cycle delay or arrest, most likely in the G(2)/M phase. In a fraction of transfected cells expressing coronavirus N proteins, we observed multinucleate cells and dividing cells with nucleoli (which are only present during interphase). These findings are consistent with the possible inhibition of cytokinesis in these cells.

Animals↗
PubMed2000

An adenovirus E1A mutant that demonstrates potent and selective systemic anti-tumoral efficacy.

Replication-selective oncolytic viruses constitute a rapidly evolving and new treatment platform for cancer. Gene-deleted viruses have been engineered for tumor selectivity, but these gene deletions also reduce the anti-cancer potency of the viruses. We have identified an E1A mutant adenovirus, dl922-947, that replicates in and lyses a broad range of cancer cells with abnormalities in cell-cycle checkpoints. This mutant demonstrated reduced S-phase induction and replication in non-proliferating normal cells, and superior in vivo potency relative to other gene-deleted adenoviruses. In some cancers, its potency was superior to even wild-type adenovirus. Intravenous administration reduced the incidence of metastases in a breast tumor xenograft model. dl922-947 holds promise as a potent, replication-selective virus for the local and systemic treatment of cancer.

Adenoviridae↗
PubMed1999

Altered expression of cell cycle proteins and prolonged duration of cardiac myocyte hyperplasia in p27KIP1 knockout mice.

-The precise role of cell cycle-dependent molecules in controlling the switch from cardiac myocyte hyperplasia to hypertrophy remains to be determined. We report that loss of p27(KIP1) in the mouse results in a significant increase in heart size and in the total number of cardiac myocytes. In comparison to p27(KIP1)+/+ myocytes, the percentage of neonatal p27(KIP1)-/- myocytes in S phase was increased significantly, concomitant with a significant decrease in the percentage of G(0)/G(1) cells. The expressions of proliferating cell nuclear antigen, G(1)/S and G(2)/M phase-acting cyclins, and cyclin-dependent kinases (CDKs) were upregulated significantly in ventricular tissue obtained from early neonatal p27(KIP1)-/- mice, concomitant with a substantial decrease in the expressions of G(1) phase-acting cyclins and CDKs. Furthermore, mRNA expressions of the embryonic genes atrial natriuretic factor and alpha-skeletal actin were detectable at significant levels in neonatal and adult p27(KIP1)-/- mouse hearts but were undetectable in p27(KIP1)+/+ hearts. In addition, loss of p27(KIP1) was not compensated for by the upregulation of other CDK inhibitors. Thus, the loss of p27(KIP1) results in prolonged proliferation of the mouse cardiac myocyte and perturbation of myocyte hypertrophy.

3T3 Cells↗
PubMed1999

The cell cycle and drug discovery: the promise and the hope.

In recent years, there have been major developments in the understanding of the cell cycle. It is now known that normal cellular proliferation is tightly regulated by the activation and deactivation of a series of proteins that constitute the cell cycle machinery. The expression and activity of components of the cell cycle can be altered during the development of a variety of diseases where aberrant proliferation contributes to the pathology of the illness. Apart from yielding a new source of untapped therapeutic targets, it is likely that manipulating the activity of such proteins in diseased states will provide an important route for treating proliferative disorders, and the opportunity to develop a novel class of future medicines.

Journal Article↗
PubMed1999

Cell cycle regulatory molecules (cyclins, cyclin-dependent kinases and cyclin-dependent kinase inhibitors) and the cardiovascular system; potential targets for therapy?

In the preceding sections we have described the potential for using cell cycle regulatory molecules as targets for drug development within the cardiovascular system. Opportunities for affecting the expression and activities of selected cell cycle regulatory molecules exist in interventional cardiological procedures such as PTCA to limit specifically the intimal hyperplasia of vascular smooth muscle cells that occurs following angioplasty. In addition, the potential for targeting the cardiac myocyte cell cycle to re-initiate cell division in a controlled manner would provide a suitable approach for repairing damaged areas of myocardial tissue following an infarct. Although this approach has not been demonstrated to date in vivo, data from transgenic mouse models and in vitro studies have implicated the cell cycle as a suitable target for manipulation. The next few years will enable the feasibility of this approach to be demonstrated.

Animals↗
PubMed1998

Cell cycle profiles and expressions of p21CIP1 AND P27KIP1 during myocyte development.

The ability of the cardiac myocyte to divide ceases shortly after birth. Thus, following severe injury, e.g., during myocardial infarction, the mature heart is unable to regenerate new tissue to replace the dead or damaged tissue. The identification of the molecules controlling the cessation of myocyte cell division may lead to therapeutic strategies which aim to re-populate the damaged myocardial area. Hence, we have determined the cell cycle profile, expressions and activities of the cyclin-dependent kinase inhibitors (CDKIs), p21CIP1 and p27KIP1, during rat ventricular myocyte development. Fluorescent activated cell sorting (FACS) analyses showed the percentage of S phase myocytes to be decreased significantly throughout development, concomitant with a significant increase in the percentage of G0/G1 and G2/M phase cells. The expression of p21CIP1 and p27KIP1 increased significantly throughout cardiac development and complexed differentially with a number of cyclins and CDKs. Furthermore, an adult myocyte extract reduced neonatal myocyte CDK2 kinase activity significantly (>30%, p<0.05) whereas immunodepletion of p21CIP1 from adult lysates restored CDK2 kinase activity. Thus, p21CIP1 and p27KIP1 may be important for the withdrawal of cardiac myocytes from the cell cycle and for maintaining the G0/G1 and G2/M phase blockades.

Animals↗
PubMed1998

Diacylglycerol-induced protection against injury during ischemia and reperfusion in the rat heart: comparative studies with ischemic preconditioning.

The role of protein kinase C (PKC) activation in ischemic preconditioning remains controversial. Since diacylglycerol is the endogenous activator of PKC and as such might be expected cardioprotective, we have investigated whether: (i) the diacylglycerol analog 1,2-dioctanoyl-sn-glycerol (DOG) can protect against injury during ischemia and reperfusion; (ii) any effect is mediated via PKC activation; and (iii) the outcome is influenced by the time of administration. Isolated rat hearts were perfused with buffer at 37 degrees C and paced at 400 bpm. In Study 1, hearts (n=6/group) were subjected to one of the following: (1) 36 min aerobic perfusion (controls); (2) 20 min aerobic perfusion plus ischemic preconditioning (3 min ischemia/3 min reperfusion+5 min ischemia/5 min reperfusion); (3) aerobic perfusion with buffer containing DOG (10 microM) given as a substitute for ischemic preconditioning; (4) aerobic perfusion with DOG (10 microM) during the last 2 min of aerobic perfusion. All hearts then were subjected to 35 min of global ischemia and 40 min reperfusion. A further group (5) were perfused with DOG (10 microM) for the first 2 min of reperfusion. Ischemic preconditioning improved postischemic recovery of LVDP from 24+/-3% in controls to 71+/-2% (P < 0.05). Recovery of LVDP also was enhanced by DOG when given just before ischemia (54+/-4%), however, DOG had no effect on the recovery of LVDP when used as a substitute for ischemic preconditioning (22+/-5%) or when given during reperfusion (29+/-6%). In Study 2, the first four groups of study were repeated (n=4-5/group) without imposing the periods of ischemia and reperfusion, instead hearts were taken for the measurement of PKC activity (pmol/min/mg protein+/-SEM). PKC activity after 36 min in groups (1), (2), (3) and (4) was: 332+/-102, 299+/-63, 521+/-144, and 340+/-113 and the membrane:cytosolic PKC activity ratio was: 5.6+/-1.5, 5.3+/-1.8, 6.6+/-2.7, and 3.9+/-2.1 (P=NS in each instance). In conclusion, DOG is cardioprotective but under the conditions of the present study is less cardioprotective than ischemic preconditioning, furthermore the protection does not appear to necessitate PKC activation prior to ischemia.

Animals↗
PubMed1998

Differential changes in transforming growth factor-beta isoform expression during postnatal cardiac growth.

Transforming growth factor-beta (TGF-beta) is synthesised as an inactive precursor protein; this is cleaved to produce the mature peptide and a latency associated protein (LAP), which remains associated with the mature peptide until activation by LAP degradation. Isoform specific antibodies raised against the LAPs for TGF-beta 2 and -beta 3 were used to determine the myocardial levels of LAP (activatable TGF-beta) and full length precursor (inactive TGF-beta) forms during post-natal development in the rat. TGF-beta 2 was present predominantly as the precursor in 2 day old myocardium. There was an age-dependent shift from precursor protein to LAP between 2 and 28 days. A corresponding increase in the level of mature (activatable) TGF-beta 2 was found. TGF-beta 3 was detected in significant quantities only as LAP. However, a four-fold increase in the expression of TGF-beta 3 LAP was observed between 2 and 28 days. The substantial increases in activatable forms of TGF-beta 2 and -beta 3 that occur in myocardium during the first 28 days of life in the rat support a role for these proteins in post-natal cardiac development.

Amino Acid Sequence↗