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Biomedical subjects

G Davies

Publications and source records attributed to G Davies.

At least 37 records · Page 2Linked to original sources
PubMed2005

Hepatocyte growth factor/scatter factor and prostate cancer: a review.

Men who die from prostate cancer do so from uncontrolled metastatic disease. A better understanding of the mechanisms involved in the progression and metastasis of prostate cancer may lead to novel therapeutic approaches to prevent its natural progression. Hepatocyte Growth Factor / Scatter factor (HGF/SF) has been demonstrated to elicit a number of key functions in numerous tissues that are important in the progression, invasion and metastasis of cancer. Studies have demonstrated that the activity of HGF/SF and its receptor c-Met are linked to disease progression in numerous cancers. However, research into these functions, which include activities as a mitogen, a motogen and an anti-apoptotic and angiogenic factor in prostate cancer are limited. This article reviews the published evidence of the roles HGF/SF plays in prostate cancer progression and highlights the clinical and therapeutic potential of research into this pleiomorphic cytokine.

Animals↗
PubMed2004

Evaluation of novel beta-ribosidase substrates for the differentiation of Gram-negative bacteria.

AIMS: To synthesize novel substrates for the detection of beta-ribosidase and assess their potential for the differentiation of Gram-negative bacteria. METHODS AND RESULTS: Two novel chromogenic substrates, 3',4'-dihydroxyflavone-4'-beta-D-ribofuranoside (DHF-riboside) and 5-bromo-4-chloro-3-indolyl-beta-D-ribofuranoside (X-riboside) were evaluated along with a known fluorogenic substrate, 4-methylumbelliferyl-beta-D-ribofuranoside (4MU-riboside). A total of 543 Gram-negative bacilli were cultured on media containing either DHF-riboside or X-riboside. Hydrolysis of DHF-riboside or X-riboside resulted in the formation of clearly distinguishable black or blue-green colonies, respectively. Hydrolysis of 4MU-riboside was evaluated in a liquid medium in microtiter trays and yielded blue fluorescence on hydrolysis which was measured using fluorimetry. beta-Ribosidase activity was widespread with 75% of strains, including 85.6% of Enterobacteriaceae, showing activity with at least one substrate. Genera that demonstrated beta-ribosidase activity included Aeromonas, Citrobacter, Enterobacter, Escherichia, Hafnia, Klebsiella, Morganella, Providencia, Pseudomonas, Salmonella and Shigella. In contrast, strains of Proteus spp., Acinetobacter spp., Yersinia enterocolitica, Vibrio cholerae and Vibrio parahaemolyticus generally failed to demonstrate beta-ribosidase activity. CONCLUSIONS: The novel substrates DHF-riboside and X-riboside are effective for the detection of beta-ribosidase in agar-based media and may be useful for the differentiation and identification of Gram-negative bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report describing the application and utility of chromogenic substrates for beta-ribosidase. These substrates could be applied in chromogenic media for differentiation of Gram-negative bacteria.

Bacterial Typing Techniques↗
PubMed2004

Absence of macrocytic anaemia in Alzheimer's disease.

There is an association between Alzheimer's disease (AD) and low serum levels of vitamin B12 and folic acid. Patients also have elevated serum levels of homocysteine and disease progression might therefore be associated with the development of a macrocytic anaemia. We investigated the relationship between disease duration, homocysteine and haematological indices in patients with clinically diagnosed AD and healthy elderly controls. Haemoglobin and platelet counts fell only slightly with increasing dementia duration, but there were no other changes in haematological indices. In particular, macrocytosis and red cell distribution width were unrelated to disease duration and no patients were anaemic. Our results support previous observations that the neurological and haematological features of B12 and folate deficiency are often unrelated in these patients.

Aged↗
PubMed2003

Multiresistant Pseudomonas aeruginosa in a pediatric cystic fibrosis center: natural history and implications for segregation.

It has been suggested that cystic fibrosis (CF) patients harboring multiresistant (MR) Pseudomonas aeruginosa (PA) should be seen in separate clinics. The aim of this study was to test the feasibility of this by longitudinally studying the consistency of isolates of MRPA in individuals. We analyzed all respiratory tract cultures undertaken in 1 year from a pediatric CF clinic population (n = 367). PA was classified as MR according to the definition of the American CF Foundation: resistance to all agents in at least two of the following groups of antibiotics: beta-lactams, aminoglycosides, and fluroquinolones. PA was cultured from 96 children during the year of study. Thirty-six were infected with at least one MR strain. Following initial identification of MRPA, MR in subsequent cultures was highly variable. Twenty-three of 36 patients had subsequent cultures in which PA was identified. However, 21 of 23 patients had at least one isolate that was not MR following detection of MRPA. The variability with time in isolation of MR strains from individuals demonstrates the potential difficulties in designing segregation policies based on antibiotic sensitivity patterns.

Adolescent↗
PubMed2003

OM197-MP-AC induces the maturation of human dendritic cells and promotes a primary T cell response.

Dendritic cell (DC) maturation is critical for the induction of antigen-specific T lymphocyte responses and may be essential for the development of human vaccines relying on T cell immunity. We investigated the effects on human DC of OM-197, a synthetic pseudodipeptide derived from amino acids, linked to three fatty acid chains and devoid of endotoxin properties. OM-197 upregulated the expression of HLA-DR, CD80, CD86, CD83, CD40 and CD54 at the surface of myeloid DC naturally present in blood as well as of DC generated in vitro from monocytes using IL-4 and GM-CSF. OM-197 also induced the release of IL-12 and TNF-alpha from DC. Finally, DC incubated with OM-197 after pulsing with hepatitis B surface antigen (HBs Ag) induced in vitro expansion of IFN-gamma-secreting HBs Ag-specific CD4(+) T lymphocytes from naive individuals. Taken together, these data identify OM-197 as a potential vaccine adjuvant for the induction of Th1-type responses.

CD4 Antigens↗
PubMed2003

Tension pneumothorax: eyes may be more diagnostic than ears.

A case is presented of unilateral tension pneumothorax in an awake patient who was seen in prehospital care after a significant fall. Because of extrication difficulties it was 40 minutes after the accident when he was first seen and by this stage the tension pneumothorax was well developed. Many features that are taught as "classic" of tension pneumothorax were absent but various other clinical signs were present to aid the diagnosis, and these are reviewed.

Accidental Falls↗
PubMed2003

Inflammatory and thrombotic mechanisms in coronary atherosclerosis.

Many molecular and cellular mechanisms link inflammation and haemostatic mechanisms. Inflammation, and perhaps chronic infection, may play important roles in the initiation and progression of atherosclerosis. Atherosclerotic lesions are heavily infiltrated by cellular components associated with inflammation (macrophages and T lymphocytes), and acute plaque rupture is also associated with inflammatory components. Several markers of systemic inflammation may predict future cardiovascular events in apparently healthy subjects as well as in patients with chronic and acute syndromes. There may thus be therapeutic potential in modifying the atherosclerotic, vasomotor, and thrombotic components of ischaemic heart disease.

Arteritis↗
PubMed2002

Modelling vaccination strategies against foot-and-mouth disease.

Vaccination has proved a powerful defence against a range of infectious diseases of humans and animals. However, its potential to control major epidemics of foot-and-mouth disease (FMD) in livestock is contentious. Using an individual farm-based model, we consider either national prophylactic vaccination campaigns in advance of an outbreak, or combinations of reactive vaccination and culling strategies during an epidemic. Consistent with standard epidemiological theory, mass prophylactic vaccination could reduce greatly the potential for a major epidemic, while the targeting of high-risk farms increases efficiency. Given sufficient resources and preparation, a combination of reactive vaccination and culling might control ongoing epidemics. We also explore a reactive strategy, 'predictive' vaccination, which targets key spatial transmission loci and can reduce markedly the long tail that characterizes many FMD epidemics. These analyses have broader implications for the control of human and livestock infectious diseases in heterogeneous spatial landscapes.

Animals↗
PubMed2002

Functional vitamin B(12) deficiency and Alzheimer disease.

Moderately elevated total serum homocysteine is associated with an increased risk of atherothrombotic vascular events. Accordingly, serum homocysteine is increased in patients with vascular dementia but is also increased in clinically diagnosed and histologically confirmed AD. It is generally considered that homocysteine potentiates endothelial and neuronal oxidative injury in these diseases. A complementary model of oxidative stress-induced hyperhomocystinemia is proposed by the authors. The hypothesis accounts for several unusual features relating to single-carbon metabolism and AD, including the absence of macrocytic anemia in these patients. It is suggested that cerebral oxidative stress augments the oxidation of an intermediate form of vitamin B(12) (cob[I]alamin) generated in the methionine synthase reaction, thereby impairing the metabolism of homocysteine. Oxidative stress also compromises the intraneuronal reduction of the vitamin to its metabolically active state. Currently available pharmaceutic forms of vitamin B(12) are unlikely to be utilized by neurons under these conditions. Glutathionylcobalamin might be preferential for the treatment of such patients.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed2002

Non-myeloablative stem cell transplantation for congenital immunodeficiencies.

Allogeneic haematopoietic stem cell transplantation (HSCT) can be a highly successful treatment option for individuals with congenital immunodeficiency states. The strategy for HSCT is varied but in cases where there is preservation of residual T cell function, conditioning regimes have been used and have been based around a combination of busulphan and cyclophosphamide with or without serotherapy. In patients with coexisting organ damage this has resulted in significant morbidity and mortality. We have therefore used a low-intensity conditioning regime for transplantation in this group of immunodeficiency patients. Twenty-one patients with a variety of different immunodeficiencies were treated using the following conditioning regimes: (1) fludarabine/melphalan/ATG or Campath 1H (n=16), (2) fludarabine/cyclophosphamide/Campath 1H (n=1), (3) TBI/CyA/MMF (n=1), (4) fludarabine/melphalan/busulphan/ATG (n=3). In 13 cases matched (n=9) and 1 Ag mismatched (n=4) unrelated donors were used and in eight cases transplants from matched siblings (n=4), 1 Ag mismatched sibling (n=1), matched parent (n=1) and haploidentical parents (n=3) were performed. At a median follow-up of 13 months, 19 of 21 (90%) patients were still alive following the transplant procedure. Despite a T cell replete graft and the use of unrelated donor grafts in the majority of patients studied there was no evidence of significant organ disease. Immune reconstitution in terms of CD3+ and CD4+ T cell recovery and function was equivalent in comparison with a historical cohort. We believe that this low-intensity approach has significant implications for transplantation of individuals with immunodeficiency states with established organ disease.

Adolescent↗
PubMed2002

Loss of cytomegalovirus-specific immunological memory in a patient with thymoma.

Cytomegalovirus (CMV) retinitis is a re-activation infection associated with severely impaired T cell-mediated immunity. We describe a patient with long-standing Crohn's disease and thymoma who developed severe CMV retinitis. While thymoma can be associated with impaired humoral immunity and a quantitative CD4+ T helper cell deficiency, these were not evident in our patient. However, more detailed investigation of anti-CMV responses showed absence of specific T cell responses to CMV antigen. Normal CMV seropositive controls have detectable proliferation and interferon-gamma production by T cells in response to stimulation with CMV antigen, but this was absent in this patient both during the acute infection and in convalescence. Other measures of T cell function were normal. Since CMV retinitis is due to reactivation of latent CMV infection, it appears that selective loss of CMV-specific immunity had occurred, perhaps secondary to a thymoma. The causes of thymoma-associated immune impairment are not understood, but this case demonstrates that selective defects can occur in the absence of global T cell impairment. Opportunistic infections should therefore be suspected in patients with thymoma even in the absence of quantitative immune deficiencies.

Aged↗
PubMed2002

Determinants of migraine-specific quality of life.

This paper reports an analysis of two randomized controlled trials of rizatriptan, in which the 24-h Migraine Quality of Life QuestionnaireCopyright was used to assess migraine-specific quality of life in patients receiving acute treatment. The objective of the analysis was to determine which clinical effects of a migraine medication, as measured by traditional clinical trial endpoints, contribute to a better short-term health-related quality of life. The results demonstrate that patients who experience complete pain relief and are able to function at their normal ability within 2 h and experience no headache recurrence have the highest migraine-specific quality of life scores. Patients who were satisfied with medication at 2 h had higher migraine-specific quality of life scores than those who were not satisfied. In conclusion, migraine therapy that provides rapid, complete, and sustained pain relief, with restoration of functional ability, has the most beneficial impact on short-term health-related quality of life for migraineurs.

Adult↗
PubMed2002

Proctitis with caecitis: an atypical presentation of ulcerative colitis.

Ulcerative colitis is characterized as an inflammatory process of the distal colonic mucosa, which may extend proximally. Its proximal extension is classically as a continuous lesion. We describe six patients presenting with typical ulcerative proctiits, who were also found to have an inflammatory area in the caecum, while the remaining colon was macroscopically and histologically normal. With no features to support a diagnosis of Crohn's disease, we believe these cases challenge the classic teaching that ulcerative colitis is a continuous disease. Performing total colonoscopy in patients who seem to have solely distal colitis will permit recognition of this distribution of inflammation.

Adult↗
PubMed2002

Cyclooxygenase-2 (COX-2), aromatase and breast cancer: a possible role for COX-2 inhibitors in breast cancer chemoprevention.

Interest in chemoprevention in oncology using suppressants of prostaglandin (PG) synthesis has been stimulated by epidemiological observations that the use of aspirin and other non-steroidal inflammatory drugs (NSAIDs) is associated with reduced incidence of some cancers, including cancer of the breast. The main target of NSAID activity is the cyclooxygenase (COX) enzyme. Two isoforms of COX have been identified: COX-1, the constitutive isoform; and COX-2. the inducible form of the enzyme. COX-2 can undergo rapid induction in response to many factors such as bacterial lipopolysaccharides, growth factors, cytokines and phorbol esters. COX-2 is overexpressed in some malignancies including carcinoma of the breast. It has been suggested that such enhanced expression may lead to increased angiogenesis such that the inhibition of COX-2 might have a general anticancer effect via decreased blood vessel formation. In addition, an association between COX-2, its main product PGE2 and aromatase activity in human breast cancer suggests that such inhibitors might have an additional, specific prophylactic mechanism for this tumour. New COX-2 inhibitors are already licensed for use in the treatment of arthritis and are well tolerated. Their potential role in chemoprevention of mammary carcinogenesis in rats has already been investigated. What remains to be seen is if these findings can be extrapolated to human studies.

Animals↗