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Biomedical subjects

R Kingston

Publications and source records attributed to R Kingston.

At least 19 recordsLinked to original sources
PubMed1999

Ikaros DNA-binding proteins direct formation of chromatin remodeling complexes in lymphocytes.

The Ikaros gene family encodes zinc finger DNA-binding proteins essential for lineage determination and control of proliferation in the lymphoid system. Here, we report that, in the nucleus of a T cell, a major fraction of Ikaros and Aiolos proteins associate with the DNA-dependent ATPase Mi-2 and histone deacetylases, in a 2 MD complex. This Ikaros-NURD complex is active in chromatin remodeling and histone deacetylation. Upon T cell activation, Ikaros recruits Mi-2/HDAC to regions of heterochromatin. These studies reveal that Ikaros proteins are capable of targeting chromatin remodeling and deacetylation complexes in vivo. We propose that the restructuring of chromatin is a key aspect of Ikaros function in lymphocyte differentiation.

Adenosine Triphosphatases↗
PubMed1999

Physical and psychological needs of patients dying from colo-rectal cancer.

Sixty-one patients suffering from terminal colo-rectal cancer were interviewed in depth by trained research nurses. The nurses used a semistructured interview, a concerns checklist and the Psychiatric Assessment Schedule to determine patients' key physical complaints, their main concerns and whether or not an affective disorder was present. The interviewers' estimates of these aspects were then compared with the assessments of 48 carers and 58 general practitioners (GPs). The congruence between patients' and carers' reports was reasonable for appetite loss (77%), nausea and vomiting (75%) and pain (72%), and the rate of false positive reporting was low. However, there was much less congruence for breathlessness (48%) and pyrexia (32%). There was even less congruence between the estimates of patients' physical symptoms and GPs' perceptions. The highest congruence was for pain (42%). The congruence was low for appetite loss (8%) and breathlessness (5%). The congruence between patients' and carers' perceptions of the patients' major concerns was low, being at best 33% for patients' concerns about their physical illness. The rate of false positive reporting by carers was high. The carers' major concerns included the patients' illness (47%), the future (33%) and the emotional demands being put on them (23%). Thirteen (22%) of the 59 patients completing a full interview were suffering from an affective disorder. This had been recognized by the GP in only five cases and six patients who had a normal mood were wrongly diagnosed as being depressed. Of the carers interviewed, 22 (46%) considered symptom control had been inadequate and 23 (48%) felt they had no relief from the burden of caring or had too little help. Sixteen (33%) had recently suffered from a major depressive illness, generalized anxiety disorder or adjustment disorder. It is concluded that it is unreliable to rely on carers' proxy reports of the symptoms experienced by terminally ill patients; more accurate personal assessments are needed where possible. It is likely that this will only be achieved by ensuring that those health professionals involved in palliative care have training in the relevant assessment skills.

Aged↗
PubMed1998

Direct mass spectrometric peptide profiling and sequencing of single neurons reveals differential peptide patterns in a small neuronal network.

Mass spectrometry (MS) was employed to detect and structurally characterize peptides in two functionally related neurons, named VD1 and RPD2, which form a network involved in the modulation of heartbeat in Lymnaea. Matrix-assisted laser desorption/ionization MS, directly applied to single neurons VD1 and RPD2, showed overlapping yet distinct mass profiles, with a subset of putative peptides specifically present in neuron VD1. Direct tandem MS of a single VD1 neuron revealed the primary structures of the VD1-specific peptides, which were identified as members of the family of small cardioactive peptides. Based on the tandem MS data, a degenerate oligonucleotide was made for use in a polymerase chain reaction strategy to isolate the cDNA encoding the precursor to the small cardioactive peptides from a brain-specific cDNA library. The calculated masses of the mature, posttranslationally modified peptides, as predicted from the corresponding cDNA, agreed with the measured masses of the actual peptides, as detected in single-cell MS analysis. In situ hybridization studies showed that the transcript encoding the precursor is present in VD1, but not in RPD2, thus corroborating the single-cell MS analysis. Finally, the small cardioactive peptides were shown to enhance the contractions of the auricle in vitro.

Amino Acid Sequence↗
PubMed1997

Immune responses, not promoter inactivation, are responsible for decreased long-term expression following plasmid gene transfer into skeletal muscle.

Long-term high-level in vivo gene expression appears to depend on the promoter chosen to drive the gene of choice. In many cases the promoter appears to 'switch off' some time after in vivo gene transfer. We demonstrate that, following intramuscular injection of beta-galactosidase reporter plasmids, promoter 'switch off' is due to elimination of fibres expressing the transferred reporter gene by activation of a Th1 (cytotoxic) immune response. This finding, in the absence of stimulation of the immune system by viral vector proteins, has implications not only for gene transfer experiments but for the future of muscle-directed gene therapy.

Animals↗
PubMed1997

Incidence of hereditary non-polyposis colorectal cancer in a population-based study of 1137 consecutive cases of colorectal cancer.

BACKGROUND: Previous reports have indicated that 5-13 per cent of colorectal cancer is hereditary. However, the proportion of cases arising as a result of mutations in the hereditary non-polyposis colorectal cancer (HNPCC) genes remains to be determined. METHODS: This study is a part prospective, part retrospective review of all cases of colorectal cancer from a district hospital over 14 years. Some 1137 consecutive patients with colorectal cancer were questioned about their family history of cancer and details were logged on a database. For the past 4 years each case has been re-evaluated where possible. RESULTS: Some 118 patients indicated initially that they had a first-degree relative with colorectal cancer, but on re-evaluation there were significant discrepancies. Only three cases (0.3 per cent) occurred in families which strictly fulfilled the criteria for HNPCC and there were no cases of familial adenomatous polyposis. A total of 16 patients (1.4 per cent) fulfilled looser criteria for HNPCC. CONCLUSION: This population-based study has shown a lower frequency of familial bowel cancer than previous studies and may reflect a lower incidence of inherited mutations in the HNPCC DNA mismatch repair genes than is currently accepted.

Adult↗
PubMed1995

An improved method for clenbuterol screening using high resolution selected ion recording.

A method has been developed using reliable GC derivatization techniques interfaced with a high resolution mass spectrometer. The method has proved successful for the detection of low levels (less than 1 ppm) of clenbuterol in complex biological matrices. Selected ion recording of two characteristic isotopic fragment ions provides a specific mode of detection by verifying the GC retention time of these ions and also by comparing their relative abundance. Analysis of urine samples demands higher mass spectrometric resolution, and 40 000 (10% valley) was found to be a prerequisite for accurate integration of the drug-related chromatographic peaks. The method developed is suitable for adaptation to a completely unattended automated routine incorporating sample injection, storage and retrieval of source tuning parameters, and data processing.

Adrenergic beta-Agonists↗
PubMed1995

Monoclonal antibodies identifying chick gonadal cells.

1. The aim of the present study was to raise monoclonal antibodies (MAbs) which discriminate gonadal cell types in chickens. 2. A panel of 180 MAbs was generated, from which 14 were chosen for their specificity. 3. These MAbs were characterised immunohistologically on frozen sections of embryonic, newly-hatched and adult, male and female, left gonads. 4. Three of these MAbs are described: AGC5, AGC7, and AGC13 which recognise respectively germinal epithelial cells, supporting cells and germ cells. 5. These MAbs may be useful in following the developmental pathways in the chicken gonad and analysing the interactive role(s) taking place between gonadal stromal cells and primordial germ cells.

Aging↗
PubMed1992

Gastrointestinal decontamination. Which method is best?

Why has ipecac syrup become less popular in emergency management of poisoning and overdose? When should gastric lavage, activated charcoal, cathartics, or a combination of methods be used? Which patients are candidates for whole-bowel irrigation with polyethylene glycol-electrolyte solution? Drs Harris and Kingston answer these questions and present their recommendations for each of the available management options.

Cathartics↗
PubMed1991

An improved method for the detection of DNA fragmentation.

An application of the Southern blot technique is described which permits the detection of DNA fragmentation due to cell death by apoptosis. DNA fragments were isolated from cell suspensions and tissues, separated on agarose gel, transferred by Southern blot and hybridized with a radiolabeled total cellular DNA probe. The application of this procedure to thymus cell samples, revealed the distinct ladder pattern of DNA fragments in multiples of about 180-200 base pairs, a characteristic feature of DNA fragmentation. In comparison to conventional DNA visualization with ethidium bromide staining, the radiolabeled probe improved the detection of DNA fragments at least eight-fold. This method detects low levels of DNA fragments, as well as physiological tissue DNA fragmentation, while avoiding cell damage due to DNA radiolabeling.

Animals↗
PubMed1990

Cell growth and gene rearrangement signals during the development of T lymphocytes within the thymus.

The thymus provides signals that control the proliferation and differentiation of T lymphocytes and select the repertoire of T-cell specificities. Antibodies to CD3 molecules inhibit full rearrangement of T-cell receptor beta chain genes in organ cultures of early embryo mouse thymus. Whether this effect is mediated through gamma delta CD3 expressing cells, which are present in small numbers at this stage, or through low amounts of CD3 on alpha beta precursor cells is unclear. A requirement for special gene rearrangement signals within the thymus is supported also by the observations that growth factors such as IL-2 and IL-4, although stimulating proliferation of precursor cells removed from the thymus, do not induce full T-cell receptor gene rearrangements. Recent studies show that newly formed thymic lymphocytes expressing alpha beta CD3 receptors are targets for negative selection (deletion) as a means of removing autoreactive cells. Signalling to immature thymocytes via the alpha beta CD3 complex induces the activation of endogenous endonucleases that cleave DNA into oligonucleosomal fragments. We suggest that the activation of this mechanism is the means by which autoreactive cells are removed.

Animals↗
PubMed1990

Newly generated thymocytes are not refractory to deletion when the alpha/beta component of the T cell receptor is engaged by the superantigen staphylococcal enterotoxin B.

It has been reported that, following the initial expression of the T cell receptor (TcR) alpha/beta, newly generated thymocytes pass through a developmental window characterized by ineffective coupling between the alpha/beta and CD3 components resulting in resistance to deletion (negative selection). However, we now provide evidence that the TcR alpha/beta on developing thymocytes is capable of delivering deletional signals in response to the superantigen staphylococcal enterotoxin B (SEB) as soon as the receptor is expressed. We also show that if TcR+ thymocytes are allowed to mature in organ cultures of embryonic thymus before SEB is added, they respond by proliferation giving rise to blast cells of CD4-CD8-, CD4+CD8- or CD4-CD8+ phenotypes.

Animals↗
PubMed1990

Developmentally regulated fetal thymic and extrathymic T-cell receptor gamma delta gene expression.

The gamma delta T-cell receptor (TCR) is the first TCR to be expressed in ontogeny in all vertebrates in which it has been examined thoroughly. Murine gamma delta cell-surface protein is detected by the fourteenth day of gestation. In this work, the activation of gamma delta RNA has been studied. Data indicate that the first TCR protein to appear in the thymus is encoded by gamma genes that are activated after cells colonize the thymus. However, the sequential appearance of different gamma delta TCR proteins during thymic ontogeny cannot be readily explained by differential temporal activation of V gamma genes in the thymus. There are distinct patterns of gamma and delta gene expression during fetal liver development and in the fetal gut (or tissue associated with it). Cells apparent in the liver of mice at birth express gamma delta cell-surface protein, but they disappear from the liver very soon afterward. One V gamma gene is rearranged and expressed prethymically. In addition, gamma gene expression is detectable in the livers of newborn athymic mice. Together, these observations indicate a thymic-independent pathway of activation of TCR genes.

Animals↗
PubMed1990

Induction of a cellular enzyme for energy metabolism by transforming domains of adenovirus E1a.

Brain creatine kinase is a major enzyme of cellular energy metabolism. It is overexpressed in a wide range of tumor cell lines and is used as a tumor marker. We reported recently that the promoter of the human gene has a strong sequence similarity to the adenovirus E2E promoter. This similarity suggested that the brain creatine kinase gene may be regulated by the viral activator E1a. Experiments reported here showed that both enzyme activity and mRNA levels were induced by the oncogenic products of the E1a region of adenovirus type 5, but unlike the viral E2E promoter, which is induced predominantly by E1a domain 3, brain creatine kinase induction required domains 1 and 2. These domains are important for transformation and for the association of E1a with the retinoblastoma gene product and other cellular proteins. The induction by an oncogene of a cellular gene for energy metabolism may be of significance for the metabolic events that take place after oncogenic activation.

Adenovirus Early Proteins↗
PubMed1989

Apoptosis.

Explore the source record for details and available documents.

Animals↗
PubMed1989

Antibodies to CD3/T-cell receptor complex induce death by apoptosis in immature T cells in thymic cultures.

The receptors found on most T lymphocytes bind to antigen presented on major histocompatibility complex proteins and consist of dimers of alpha- and beta-polypeptides associated with the invariant CD3 complex. A fully competent immune system requires a diverse array of T-cell antigen receptors (TCRs) with different specificities. This diversity is generated by rearrangement of TCR alpha- and beta-chain gene segments within the thymus where the receptors are first expressed. Any cells carrying self-reactive receptors must be eliminated, suppressed or inactivated so that destructive autoimmunity is avoided. Recently, compelling evidence has shown that one process involved in producing such self-tolerance is clonal deletion of autoreactive cells within the thymus by an as-yet-undefined mechanism. Here we show that engaging the CD3/TCR complex of immature mouse thymocytes with anti-CD3 antibodies produces DNA degradation and cell death through the endogenous pathway of apoptosis. Activation of this process in immature T cells by the binding of the TCR to self-antigens may therefore be the mechanism which produces clonal deletion and consequently self-tolerance.

Animals↗
PubMed1989

The effects of anti-CD2 antibodies on the differentiation of mouse thymocytes.

Using a rat monoclonal antibody against mouse CD2, we determined the expression of this marker on thymocytes during ontogeny. CD2 expression becomes detectable at day 15 and reaches adult levels (approximately 95% positivity) by day 19. Furthermore, the effect of anti-CD2 antibodies on T cell differentiation was analyzed by addition of antibodies to thymus organ cultures or repeated injection into newborn mice. Anti-CD2 antibodies inhibit CD2 expression in organ cultures and drastically reduce its expression on thymocytes and peripheral lymphocytes in vivo. In either situation, suppression of CD2 expression does not significantly alter the generation of T cells expressing CD3, CD4, CD8 and T cell receptor V beta 8. These results do not support a role for CD2 in early steps of thymocyte differentiation.

Animals↗