Search PubMed⌕ Search

Biomedical subjects

D Cox

Publications and source records attributed to D Cox.

At least 91 records · Page 5Linked to original sources
PubMed1996

The herpes simplex virus type 1 latency-associated transcript promoter is activated through Ras and Raf by nerve growth factor and sodium butyrate in PC12 cells.

Herpes simplex virus establishes latent infections in the nuclei of sensory neurons. These infections are characterized by the abundant expression of a series of 5' coterminal transcripts termed the latency-associated transcripts (LATs). Available evidence indicates that LAT expression is specifically regulated in latently infected neurons. Although previous studies have examined the regulation of LAT expression in neuronal and nonneuronal cells, the mechanism of regulation of LAT expression in neuronal cells in response to external factors has not been investigated. To address this question, we characterized the activity of LAT promoter fusion constructs in PC12 cells following treatment with nerve growth factor (NGF) and/or sodium butyrate (NaB), agents that affect expression of cell cycle-associated genes. Expression from the LAT promoter was induced 8- to 12-fold by either NGF or NaB alone and 40- to 60-fold when the two agents were added simultaneously. Fibroblast growth factor also induced expression from the LAT promoter but to a lesser extent than NGF. Treatment with factors such as epidermal growth factor, phorbol myristate acetate, cyclic AMP, or KCI had no significant effect on LAT promoter activity. Notably, promoter-reporter constructs containing immediate-early (ICP0 and ICP4), early (ICP8 and UL9), and late (UL10 and UL30) viral promoters were induced only two- to fourfold by NGF, suggesting that the LAT promoter may be unusual among herpes simplex virus genes in the magnitude of its response to this factor. To identify pathways leading to LAT activation in vitro, we characterized the response of the LAT promoter to NGF and/or NaB in PC12-derived cell lines containing mutations in specific signal transduction pathways. We found that activation of the LAT promoter requires Ras activation and that activation of the serine/threonine kinase, Raf, is sufficient to induce LAT expression. Together, these results indicate that the LAT promoter is regulated via the Ras/Raf signal transduction pathway in response to external factors such as NGF and NaB and that LAT expression may be regulated by NGF in latently infected neurons.

Animals↗
PubMed1996

Identification of cis-acting sequences in the promoter of the herpes simplex virus type 1 latency-associated transcripts required for activation by nerve growth factor and sodium butyrate in PC12 cells.

In the absence of detectable viral proteins, expression of the latency-associated transcripts (LATs) is likely regulated by cellular factors during latent infection of neurons with herpes simplex virus type 1. The amounts and activation states of these factors may in turn be regulated by extracellular regulatory factors. Consistent with this hypothesis, we have recently demonstrated that LAT expression is significantly enhanced by nerve growth factor (NGF) and sodium butyrate (NaB) in neurally derived PC12 cells. With the ultimate goal of identifying trans-acting cellular factors involved in regulating LAT expression during latency, we have attempted to identify the cis-acting elements to which these putative cellular factors bind by characterizing the LAT promoter and a series of 5' promoter deletion mutants in PC12 cells following treatment with the LAT-enhancing agents NGF and NaB. Transient expression assays demonstrated that distinct cis-acting sequences mediate basal and induced LAT promoter expression. Basal activity in PC12 cells is mediated by two elements: a negative regulatory element between -435 and -270 and a positive element between -240 and -204. The positive element contains binding sites for the transactivator Sp-1, whereas the negative element bears some resemblance to known neuron-specific silencer elements. In contrast to basal expression, maximum induction of the LAT promoter by NGF and NaB requires sequences between -159 and -81. Using gel mobility shift assays, we have identified three sets of protein-DNA complexes that bind to this 78-bp region and shown by competition analysis that binding is specific. The abundance and mobility of these complexes were altered by treatment with NGF or NaB. The nucleotide sequences to which these complexes bind were fine mapped by competition analysis with oligonucleotide probes containing substitution mutations. The target sequences identified exhibit no homology to binding sites of known transcription factors. These regions were critical for complex formation in vitro and for maximum induction of the LAT promoter by NGF and NaB in transient expression assays. The protein complexes that form with target sequences likely participate in the regulation of LAT expression in response to physiological stimuli in neurons in vivo.

Animals↗
PubMed1996

Should a doctor prescribe hormone replacement therapy which has been manufactured from mare's urine?

Many clinicians are experiencing consumer resistance to the prescription of equine HRT (that is hormone replacement therapy which has been manufactured from mare's urine). In this paper I consider the ethical implications of prescribing these preparations. I decide that patients should have a right to refuse such treatment but also ask whether a prescribing doctor should choose one preparation over another on moral grounds. I determine that there is prima facie evidence to suggest that mares may suffer and that prescription of equine HRT (instead of synthetic oestrogen-oestriol) would therefore have to be justified in terms of either offering greater benefits to the women or offering greater value for money to the health service. I find that there is no substantial evidence to suggest that equine HRT offers unique advantages over and above oestriol. I conclude that it would be preferable for a doctor to recommend the synthetic oestrogen to women who want relief from the symptoms of the menopause and protection from osteoporosis and cardiovascular disease.

Animal Rights↗
PubMed1996

Pentamidine is a specific, non-peptide, GPIIb/IIIa antagonist.

Pentamidine was previously shown to act on glycoprotein (GP) IIb/IIIa (Cox et al., Thromb Haemost 1992; 68: 731). In this paper we study the effect of pentamidine on other RGD-dependent receptors. In a cell adhesion assay, pentamidine was 500 times more potent than RGDS at inhibiting platelet adhesion to fibrinogen. While RGDS inhibited platelet adhesion to fibronectin, endothelial cell adhesion to vitronectin or fibronectin, 293 cell adhesion to vitronectin, IMR 32 cell adhesion to fibronectin and C32 cell adhesion to vitronectin; pentamidine failed to inhibit these interactions at doses as high as 1 mM. Resting platelets fixed in the presence of 1 mM RGDS had increased binding of fibrinogen, i.e., RGDS activated GPIIb/IIIa, while pentamidine at 100 microM had no effect. Similarly, RGDS induced the binding of an anti-LIBS monoclonal antibody, while pentamidine had no effect. Pentamidine partially, but significantly, inhibited lysosome and alpha-granule release induced by the thrombin agonist peptide, while RGDS had no effect. Neither pentamidine nor RGDS affected ADP-induced Ca2+ influx. Pentamidine had no effect on ADP-induced intracellular pH changes while RGDS prevented the pH from returning to normal. Thus, pentamidine is a non-peptide GPIIb/IIIa antagonist that is non-activating and is specific for GPIIb/IIIa.

Amino Acid Sequence↗
PubMed1996

Paraneoplastic intestinal pseudo-obstruction, mononeuritis multiplex, and sensory neuropathy/neuronopathy.

A patient with diffuse intestinal pseudo-obstruction consisting of gastric paresis and impaired small and large bowel motility, mononeuropathy multiplex, and sensory neuropathy/neuronopathy was found to have small-cell carcinoma of the lung. The clinical symptoms were thought to be consistent with paraneoplastic neuropathy, and high antineuronal and anti-calcium channel antibodies led to the diagnosis of small-cell carcinoma of the lung. Identification of paraneoplastic neuropathy is important, because early treatment may halt the progression of the underlying carcinoma.

Aged↗
PubMed1995

Detecting delirium among hospitalized older patients.

BACKGROUND: Delirium occurs commonly among older hospitalized patients and is frequently not recognized. In an effort to identify tools useful to clinicians in the diagnosis of delirium, test characteristics of four screening instruments were compared. METHODS: Patients 65 years of age or older who were admitted to one of four medical and surgical wards of a university teaching hospital were followed up prospectively. Potential subjects were excluded if unavailable for interviews or discharged within 48 hours of admission, or if judged too impaired to participate in the daily interviews. Research assistants administered four instruments used to detect delirium: Digit Span Test, Vigilance 'A' Test, Clinical Assessment of Confusion, and Confusion Assessment Method. Abnormal scores on these tests or suspicion of acute confusion prompted a referral to the clinician-investigators who then assessed the patient daily for delirium based on the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition criteria. RESULTS: Delirium occurred in 64 (14.8%) of 432 subjects. The positive likelihood ratios for all of the instruments were significantly more than 1. The instruments remained useful when applied to selected subgroups: subjects in whom acute mental status changes were documented, subjects on surgical services, and subjects with impaired cognitive status on admission. Combinations of any two instruments did not perform substantially better than the instrument with the best test characteristics: the Clinical Assessment of Confusion. All instruments were more useful at confirming delirium than in excluding it. CONCLUSION: The four instruments studied, which are suitable for use at the bedside, can aid the clinician in identifying patients likely to be suffering from delirium.

Aged↗
PubMed1995

Elevated levels of eosinophil major basic protein in the sera of patients with systemic sclerosis.

OBJECTIVE: To examine eosinophil activation, as reflected by evidence of eosinophil degranulation in the blood and affected tissues, in patients with diffuse and limited cutaneous forms of systemic sclerosis (SSc). METHODS: Levels of the eosinophil-derived major basic protein (MBP), a marker of eosinophil degranulation, were determined in sera from 46 SSc patients, from patients with rheumatoid arthritis and giant cell arteritis, and from healthy volunteers, and in bronchoalveolar lavage fluid from 4 SSc patients. Extracellular tissue deposition of MBP was evaluated in biopsy specimens from affected skin or lung of 11 SSc patients. RESULTS: Patients with diffuse cutaneous SSc (dcSSc) had elevated serum MBP levels compared with normal individuals (mean +/- SD 762 +/- 271 ng/ml versus 534 +/- 144 ng/ml; P = 0.0004). MBP levels were positively correlated with the extent of cutaneous involvement, and negatively correlated with pulmonary function and duration of disease (r = -0.20). By immunohistochemical analysis, modest extracellular MBP deposition could be demonstrated in involved skin in 7 of 10 biopsy specimens, and MBP staining was prominent in affected lung tissues in 2 patients. CONCLUSION: Eosinophil degranulation appears to be increased in some patients with dcSSc, as indicated by elevated serum levels of MBP and extracellular accumulation of MBP in the lung. Eosinophil granule proteins may contribute to the development of cutaneous and pulmonary fibrosis in SSc.

Adult↗
PubMed1995

Serological diagnosis of feline immunodeficiency virus infection using recombinant transmembrane glycoprotein.

We developed an antibody detection enzyme-linked immunosorbent assay (ELISA) using recombinant surface (SU), transmembrane (TM) and capsid (CA) antigens of feline immunodeficiency virus (FIV) expressed in Escherichia coli. The three antigens were tested with sera collected from experimentally infected cats in order to follow the course of seroconversion and of the antibody levels throughout the infection. An early and marked increase of TM antibodies was observed. Antibodies to TM were demonstrated at high levels throughout the observation period. The immune response to SU and to CA was less pronounced and in some cats the level of antibodies to SU and CA tended to decline 6 months after infection. In addition, 413 FIV negative and positive cat sera were tested in order to define for each antigen the diagnostic sensitivity, specificity and efficiency. TM showed the highest diagnostic sensitivity (98%) while its specificity was 97%. Its diagnostic efficiency of 97% was better than that of SU and CA and exceeded that of tests utilizing conventionally grown and gradient purified FIV. Therefore, recombinant TM can be considered a very important antigen for FIV ELISA testing. An interesting perspective is offered in the combination of TM with other recombinant antigens in a dot assay form.

Animals↗
PubMed1995

FIV vaccine studies. I. Immune response to recombinant FIV env gene products and outcome after challenge infection.

We have vaccinated five groups of cats (n = 25) four times with five preparations of recombinant feline immunodeficiency virus (FIV) env gene products; one group (n = 7) served as control. The vaccine formulations were as follows: (1) envelope glycoprotein of FIV Zurich 2 (FIV Z2) expressed in a Baculovirus system and isolated by gel electroelution (denatured form); (2) insect cells expressing FIV Z2 glycoprotein; (3) envelope glycoprotein of a Boston strain (FIV Bangston) expressed in insect cells and isolated by gel electroelution (denatured form); (4) glycosylated Bangston envelope protein made in insect cells and isolated in a native form; (5) non-glycosylated Bangston envelope protein made in Escherichia coli. All cats were challenged with 20 50% cat infective doses (CID50) of FIV Z2 previously titrated in cats. All vaccinated cats developed high enzyme-linked immunosorbent assay (ELISA) antibodies to the homologous antigen; crossreactivity to heterologous antigens was seen at a lower level. Virus neutralizing antibodies (tested with Petaluma virus) reached titers up to 32. After challenge, all cats seroconverted (as judged by anti gag antibodies in Western blot) and became infected (as judged by virus isolation and/or polymerase chain reaction) between 4 and 11 weeks with the exception of one cat. It is concluded that it is relatively easy to induce high ELISA antibody titers using recombinant env gene products, ELISA antibody titers do not correlate with virus neutralization or with protection.

Animals↗
PubMed1995

Acceleration of nitric oxide (NO) release from FK409, a spontaneous NO releaser, in the presence of sulfhydryl-bearing compounds.

PURPOSE: Recently, we have reported that FK409 spontaneously releases nitric oxide (NO) in solution. In the present study, the influence of L-cysteine (Cys) and glutathione (GSH), which are typical sulfhydryl group-bearing compounds, on NO release from FK409 and biological action of FK409 was examined. METHODS: We evaluated the effects of Cys and GSH on NO release from FK409 by nitrite analysis or detection with a chemiiluminesence analyzer. In a biological study, the influence of Cys on inhibition of rat platelet aggregation of FK409 was investigated. In addition, the above mentioned characteristics of FK409 were compared with those of isosorbide dinitrate (ISDN). RESULTS: FK409 decomposed spontaneously with generation of nitrite in solution. Both Cys and GSH accelerated decomposition of FK409 and nitrite generation from FK409 in a concentration-dependent manner. When the NO levels in the headspace of FK409 solutions (0.5 mM) reached equilibrium with and without 25 mM Cys, the constant rate for NO release from FK409 in the presence of Cys was 13 times larger than that in the absence of Cys. In biological study, FK409 (100 microM) showed 56 and 90% inhibition of rat platelet aggregation in the absence and presence of 10 mM Cys, respectively, whereas ISDN (100 microM) showed 10 and 23% inhibition, respectively. CONCLUSIONS: Decomposition of FK409 with generation of NO is spontaneous, and is accelerated in the presence of sulfhydryl group-bearing compounds, thereby potentiating the biological action of FK409.

Animals↗
PubMed1995

Genetic deletion of ABP-120 alters the three-dimensional organization of actin filaments in Dictyostelium pseudopods.

This study extends the observations on the defects in pseudopod formation of ABP-120+ and ABP-120- cells by a detailed morphological and biochemical analysis of the actin based cytoskeleton. Both ABP-120+ and ABP-120- cells polymerize the same amount of F-actin in response to stimulation with cAMP. However, unlike ABP-120+ cells, ABP-120- cells do not incorporate actin into the Triton X-100-insoluble cytoskeleton at 30-50 s, the time when ABP-120 is incorporated into the cytoskeleton and when pseudopods are extended after cAMP stimulation in wild-type cells. By confocal and electron microscopy, pseudopods extended by ABP-120- cells are not as large or thick as those produced by ABP-120+ cells and in the electron microscope, an altered filament network is found in pseudopods of ABP-120- cells when compared to pseudopods of ABP-120+ cells. The actin filaments found in areas of pseudopods in ABP-120+ cells either before or after stimulation were long, straight, and arranged into space filling orthogonal networks. Protrusions of ABP-120- cells are less three-dimensional, denser, and filled with multiple foci of aggregated filaments consistent with collapse of the filament network due to the absence of ABP-120-mediated cross-linking activity. The different organization of actin filaments may account for the diminished size of protrusions observed in living and fixed ABP-120- cells compared to ABP-120+ cells and is consistent with the role of ABP-120 in regulating pseudopod extension through its cross-linking of actin filaments.

Actin Cytoskeleton↗
PubMed1995

A multicenter evaluation of blood glucose awareness training-II.

OBJECTIVE: Blood glucose awareness training (BGAT) teaches individuals with insulin-dependent diabetes to more accurately estimate/detect their blood glucose (BG) fluctuations. It has not, however, consistently resulted in improved ability to detect low BG. To assess an enhanced version of BGAT (BGAT-II), with more focus on increasing sensitivity to low BG events, a multicenter study was undertaken. Following up on previous findings that BGAT is most effective with individuals who are least accurate in estimating BG, this study explicitly recruited subjects who did and did not report reduced awareness of hypoglycemia. RESEARCH DESIGN AND METHODS: Seventy-eight subjects from three research sites participated in a repeated baseline design. Subjects' BG estimation accuracy and BG profiles were assessed 6 months before, immediately before, and immediately after BGAT-II. RESULTS: Post-treatment, BGAT-II led to better overall accuracy in detecting BG fluctuations and better detection of both low and high BG levels. This was achieved while the number of low readings of self-monitoring of blood glucose (SMBG) was reduced. Reduction in the number of low SMBG events was significant only for subjects reporting awareness of hypoglycemia. Detection of low BG was significant only for subjects reporting reduced awareness of hypoglycemia. Both groups demonstrated equivalent improvements in detection of high BG levels. CONCLUSIONS: BGAT may be an effective behavioral strategy for reversing hypoglycemic unawareness and an adjunct to intensive insulin therapy to reduce the occurrence of severe hypoglycemia.

Adult↗
PubMed1995

Sarcoidosis in systemic sclerosis: report of 7 cases.

OBJECTIVE: To describe the clinical, radiologic, and pathologic features of coexistent systemic sclerosis (SSc) and sarcoidosis, 2 conditions of unknown cause associated with altered cellular immune response. METHODS: We reviewed clinical information, results from laboratory and radiologic studies, and lung or lymph node biopsy samples of 7 patients with concurrent SSc and sarcoidosis evaluated at 2 academic referral centers between 1989 and 1993. RESULTS: Each patient fulfilled American College of Rheumatology criteria for the classification of SSc. SSc and sarcoidosis developed simultaneously in 4 patients, whereas in 3 others sarcoidosis was diagnosed more than 6 years after the onset of SSc. The onset of sarcoidosis was characterized by fever, weight loss, or increasing respiratory symptoms. Each patient had radiographic evidence of intrathoracic lymphadenopathy and/or interstitial lung disease. Examination of lung or lymph node biopsies demonstrated noncaseating granulomas. Treatment with corticosteroids was associated with improved lung function. CONCLUSION: Since sarcoidosis coexists with SSc more frequently than previously suggested, it should be considered in patients with SSc presenting with new pulmonary symptoms. Recognizing sarcoidosis in patients with SSc is important, since these patients may benefit from corticosteroid therapy.

Adrenal Cortex Hormones↗