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Biomedical subjects

J Twigg

Publications and source records attributed to J Twigg.

14 recordsLinked to original sources
PubMed2001

NGO initiatives in risk reduction: an overview.

NGOs appear to be well placed to play a significant role in natural disaster mitigation and preparedness (DMP), working, as they do, with poorer and marginalised groups in society. However, there is little information on the scale or nature of NGO DMP activities. This paper reports the findings of a study seeking to address that gap. It confirms that NGOs are involved in a diverse range of DMP activities but that a number of them are not labelled as such. Moreover, evidence of the demonstrable quality and benefits of DMP involvement is poor. The paper concludes that a number of problems need to be overcome before DMP can be satisfactorily mainstreamed into NGO development and post-disaster rehabilitation programmes. However, there are some early indications of momentum for change.

Developing Countries↗
PubMed1998

Analysis of the impact of intracellular reactive oxygen species generation on the structural and functional integrity of human spermatozoa: lipid peroxidation, DNA fragmentation and effectiveness of antioxidants.

Exposure of human spermatozoa to nicotinamide adenine dinucleotide phosphate (NADPH) resulted in the dose dependent generation of reactive oxygen species (ROS) which, at a critical level of intensity, induced lipid peroxidation, DNA damage and a dramatic decline of sperm motility. This system was then used as a model for screening the ability of different antioxidants to combat oxidative stress created through the excessive intracellular generation of toxic oxygen products of metabolism. A variety of antioxidants that has previously been shown to be protective against extracellularly derived oxidants (e.g. superoxide dismutase, catalase, vitamin E, hypotaurine) were ineffective in this system. Albumin, however, could provide complete protection against NADPH induced oxidative stress via mechanisms that did not involve the suppression of the lipid peroxidation cascade but rather the inactivation of lipid peroxides generated during this process. Albumin did not protect against DNA damage induced by NADPH but was extremely effective at preventing DNA fragmentation arising from the suppression of glutathione peroxidase activity with mercaptosuccinate. These studies emphasize that the design of clinically effective antioxidant treatments will depend, critically, upon the source of the oxidative stress. For cases involving excessive intracellular ROS generation, albumin appears to be an important means of neutralizing lipid peroxide-mediated damage to the sperm plasma membrane and DNA.

Antioxidants↗
PubMed1998

Iatrogenic DNA damage induced in human spermatozoa during sperm preparation: protective significance of seminal plasma.

Before the advent of intracytoplasmic sperm injection (ICSI) semen preparation techniques focused on the need to sustain the fertilizing potential of the spermatozoa particularly by reducing oxidative stress. However, for severely oligozoospermic patients treated by ICSI, sperm preparation protocols are used which aim to maximize sperm recovery rather than sperm function. In this study we have examined the impact of different sperm preparation techniques on oxidative stress, sperm motion and DNA integrity. Reactive oxygen species (ROS) generation was monitored using luminol-dependent chemiluminescence, seminal antioxidant activity was assessed using a total reactive antioxidant potential (TRAP) assay while sperm motility and DNA damage were evaluated using computer assisted semen analysis and in-situ nick translation respectively. The results demonstrate a significant increase in the levels of ROS generated by samples prepared by swim-up from a washed pellet compared with spermatozoa isolated directly from seminal plasma. This oxidative stress was associated with a highly significant increase in the level of DNA damage sustained by the spermatozoa while the quality of sperm motility remained largely unchanged. These results suggest that if repeated centifugation protocols are to be used to prepare spermatozoa, strategies should be developed for minimizing collateral DNA damage.

Centrifugation, Density Gradient↗
PubMed1993

Notes: a suitable case for audit.

The increasing emphasis on management responsibilities and audit led us to investigate the state of surgical notes in our hospital. Twelve criteria were evaluated regarding information that should be contained in the notes and the absence of this important information was documented. Deficiencies were revealed in all criteria selected. Until hospital patients files are well kept and maintained, retrospective audit whether financial or medical will not be valid. A significant injection of resources is required to redress the situation. Hospitals which have not carried out detailed studies into the contents of their notes need to do so as a matter of urgency.

Humans↗
PubMed1989

Models of carers: how do social care agencies conceptualise their relationship with informal carers?

Carers occupy an ambiguous position within the social care system. Services are predominantly structured around the dependent rather than the carer, and this has important consequences for their delivery and evaluation. Many of the problems that arise in thinking about carer issues relate to confusion over the way the relationship between social care agencies and informal carers should be perceived. The paper outlines three models that provide frames of reference for this relationship: carers as resources; carers as co-workers; and carers as co-clients. The tensions between these are then used to explore the contradictions of policy in this field.

Models, Theoretical↗
PubMed1989

Calcium-induced chromatin condensation and cyclin phosphorylation during chromatin condensation cycles in ammonia-activated sea urchin eggs.

Ammonia-activated sea urchin eggs undergo repeated cycles of DNA synthesis, nuclear envelope breakdown (NEB) and chromatin condensation. No mitotic spindle forms, nor do the eggs undergo cytokinesis. Ammonia-activated eggs exhibit a form of the cell cycle in which the nuclear cycle proceeds without segregation of the chromatin into daughter cells. We discuss here experiments that demonstrate that intracellular free calcium concentration controls the S phase-M phase transition in ammonia-activated eggs, as it does in fertilized embryos. Cyclins are proteins that are synthesized throughout the cell cycle and destroyed abruptly during each round of chromatin condensation. We find that cycles of cyclin phosphorylation and destruction occur coincident with chromatin condensation in ammonia-activated eggs. Cyclin phosphorylation also occurs in eggs treated with the tumour promoter, phorbol myristate acetate (PMA). There is no accompanying NEB or chromatin condensation, however, and the nucleus is insensitive to exogenously-generated calcium transients. These latter data indicate that cyclin synthesis and phosphorylation is not a sufficient condition for calcium-induced NEB in sea urchin embryos. PMA must fail to induce one of the necessary cell cycle initiation signals. We suggest that the missing signal is the activation of the cell cycle control protein p34cdc2, which we have shown to be phosphorylated at fertilization and which is phosphorylated in ammonia-activated eggs.

Ammonia↗
PubMed1988

Translational control of InsP3-induced chromatin condensation during the early cell cycles of sea urchin embryos.

The cycles of DNA synthesis and chromatin condensation in dividing cells are controlled by signals from the cytoplasm. Changes in the concentration of free calcium (Cai) in the cytoplasm control a variety of cellular functions and it has thus been suggested that observed variations in Cai during the cell cycle may be the cytoplasmic signal that co-ordinates nuclear and cytoplasmic division. We show here that increases in Cai induced by the calcium-releasing second messenger inositol 1,4,5-triphosphate (Ins(1,4,5)P3), or by calcium buffers, cause premature chromatin condensation and breakdown of the nuclear envelope in sea urchin (Lytechinus pictus) early embryos. Both natural and induced chromatin condensation are prevented by calcium chelators. The nucleus becomes sensitive to the Cai signal 45 min after fertilization, but remains insensitive if protein synthesis is prevented. Our experiments demonstrate that Cai regulates the behaviour of the nucleus during the cell cycle, suggest that Ins(1,4,5)P3 is a cell cycle messenger and indicate that there is an interaction between the protein and ionic signals that control the state of chromatin during the cell cycle.

Animals↗
PubMedDate not supplied

Day breaks.

Explore the source record for details and available documents.

Caregivers↗
PubMedDate not supplied

Community nursing: nurses' effectiveness in supporting carers.

This article outlines the results of a research project to evaluate the effectiveness of service support to informal carers. There are many ways in which community nurses can support carers, and carers frequently report the benefits of the service. The potential significance of the community nursing service in this role, however, is yet to be realised as nursing is still highly task-orientated, with priority given to specific medical interventions. As a result, some carers face difficulties in obtaining nursing support.

Community Health Nursing↗