Biomedical subjects

S C Wright

Publications and source records attributed to S C Wright.

At least 19 recordsLinked to original sources

PubMed2004

Use of narcotic analgesics in the emergency department treatment of migraine headache.

OBJECTIVE: Treatment of acute migraine headache with narcotics is potentially ineffective and may lead to abuse. The authors examined the treatment practice variation across five linked EDs in one Canadian center, focusing on the use of narcotic analgesics and factors associated with their use. METHODS: Five hundred acute migraine headache patient charts were randomly selected from five Canadian EDs. Charts underwent a structured review to determine medication use. Data were analyzed, comparing those who received narcotics as first-line treatment with those who did not, using chi(2) and t-tests and logistic regression. RESULTS: The majority of patients (59.6%) received narcotics as first-line treatment. Numerous factors were associated with first-line narcotic treatment. Having taken antiheadache medications prior to ED presentation (odds ratio [OR]: 2.63; 95% CI: 1.53, 4.51) and hospital of presentation being other than Hospital A (e.g., Hospital D, OR: 6.32; 95% CI: 2.76, 14.46) increased the odds of receiving first-line narcotics. Having received a more urgent triage score (OR: 0.4; 95% CI: 0.24, 0.65) or having a longer duration of headache (OR: 0.994; 95% CI: 0.99, 0.99) decreased the odds of receiving first-line narcotics. CONCLUSIONS: Acute migraine management in these EDs does not meet current consensus guidelines. Factors associated with narcotic use are predictable, and a concerted effort to replace narcotics with more evidence-based first-line treatments is needed.

Adult↗

PubMed2001

S-phase-specific expression of the Mad3 gene in proliferating and differentiating cells.

The Myc/Max/Mad transcription factor network plays a central role in the control of cellular proliferation, differentiation and apoptosis. In order to elucidate the biological function of Mad3, we have analysed the precise temporal patterns of Mad3 mRNA expression during the cell cycle and differentiation in cultured cells. We show that Mad3 is induced at the G1/S transition in proliferating cells; expression persists throughout S-phase, and then declines as cells pass through G2 and mitosis. The expression pattern of Mad3 is coincident with that of Cdc2 throughout the cell cycle. In contrast, the expression of Mad3 during differentiation of cultured mouse erythroleukemia cells shows two transient peaks of induction. The first of these occurs at the onset of differentiation, and does not correlate with the S-phase of the cell cycle, whereas the second is coincident with the S-phase burst that precedes the terminal stages of differentiation. Our results therefore suggest that Mad3 serves a cell-cycle-related function in both proliferating and differentiating cells, and that it may also have a distinct role at various stages of differentiation.

3T3 Cells↗

PubMed2001

An internal ribosome entry segment in the 5' untranslated region of the mnt gene.

Mnt is a transcriptional repressor related to the Myc/Mad family of transcription factors. It is expressed in proliferating, resting and differentiating cells and is believed to antagonize the function of Myc. Here we have characterized the major transcription initiation site of the mnt gene. In doing so we noted a remarkable level of sequence conservation between the murine and human 5' untranslated regions. Our experiments revealed that this sequence contains an internal ribosome entry segment (IRES). In addition, we show that sequences at both the 5' and 3' end of the IRES are essential for its function. These findings indicate that mnt can be translated by internal initiation. Such a mechanism may allow efficient Mnt synthesis when cap-dependent translation initiation is reduced.

5' Untranslated Regions↗

PubMed2000

Synthesis and preliminary biological evaluations of CC-1065 analogues: effects of different linkers and terminal amides on biological activity.

CC-1065 analogues possessing a biologically active CBI functional group and amide-substituted indole and benzofuran were synthesized. The IC(50) values of compounds 26, bearing two indoles, and 25, bearing only one indole, are 0.4 and 3 nM, respectively, against U937 leukemia cells in vitro. The IC(50) values of compounds 28, bearing a butyramino group, and 27, bearing an acetamino group, are 0.008 and 0.4 nM, respectively, against U937 leukemia cells in vitro. Compound 29, bearing a double-bond linker, is about 4-fold more potent than 25, bearing no double-bond linker. Compound 26 is highly potent against all cell lines tested in the NCI in vitro screening with IC(50) values in the 0.1-5 nM range for most cell lines. Compounds 26 and 30 are highly active against L1210 leukemia in mice. Compound 26 is also active against B16BL6 melanoma in mice. Most importantly, 26 and 30 are not myelosuppressive at therapeutically effective doses. The mechanism of tumor cell death is through induction of apoptosis, and is accompanied by DNA fragmentation.

Animals↗

PubMed1999

Scottish Confidential Inquiry into Asthma Deaths (SCIAD), 1994-6.

BACKGROUND: There have been important changes in the organisation of care for patients with asthma since asthma deaths were studied in the 1980s by the British Thoracic Association (BTA), with greater emphasis on long term control of symptoms and the use of preventive therapy. Recent trends in routine statistics show a decline in population death rates. METHODS: A confidential review was undertaken of general practice and hospital records and interviews with general practitioners of patients dying in mainland Scotland between January 1994 and December 1996 with a principal diagnosis of asthma recorded by the Registrar General's Office. Panel assessment of the cause of death was carried out and a number of possible adverse factors were identified. The data from the 15-64 year age group were compared with similar data from the earlier study by the BTA. RESULTS: Over the three year period 95 deaths of 235 studied (40%) were confirmed as being due to asthma. Taking account of different methods of case ascertainment used in the BTA and this study, a fall in the calculated rate of "deaths assessed as due to asthma" was found from 2.51 (95% CI 2.34 to 2.68) per 100,000 population in 1979 to 1.26 (95% CI 1.19 to 1.33) per 100,000 population in 1994-6. Fewer individual adverse factors were identified in clinical management, with appropriate routine management in 59% and management of the final attack satisfactory in 71%. Patient factors such as poor compliance, lack of peak expiratory flow (PEF) measurements, and overuse of reliever medication without inhaled corticosteroids, and psychosocial problems, notably depression, were confirmed as important contributing factors. Four of five patients under 16 years of age who died were found to have problems with routine management. CONCLUSIONS: This population based study documents important improvements in the standard of asthma care as well as a significant decline in the rate of deaths due to asthma over a period during which the organisation of care has changed and the chronic nature of the disease has been acknowledged. Strategies which might have a further impact include the greater use of PEF recordings, particularly during acute attacks, to document recovery, prescription monitoring of the underuse of inhaled corticosteroids, consideration of the use of combined preparations where persistent overuse of bronchodilators is occurring, and increased input for young patients whose routine management is proving difficult.

Adolescent↗

PubMed1998

Bcl-2-mediated resistance to apoptosis is associated with glutathione-induced inhibition of AP24 activation of nuclear DNA fragmentation.

Studies on the mechanism of apoptosis in this laboratory support a model in which signal transduction involving caspase 3 leads to activation of a serine protease called Mr 24,000 apoptotic protease (AP24), which then induces internucleosomal DNA fragmentation in the nucleus. This study examined the effect of Bcl-2 overexpression on activation of AP24 and the induction of DNA fragmentation by AP24 in isolated nuclei. It was demonstrated that overexpression of Bcl-2 in either HL-60 or PW leukemia cell lines suppressed activation of AP24 induced by either tumor necrosis factor or UV light and protected cells from apoptosis. Furthermore, nuclei isolated from Bcl-2-overexpressing cells were relatively resistant to internucleosomal DNA fragmentation induced by AP24 isolated from apoptotic cells. Bcl-2-overexpressing cells that were nutritionally depleted of glutathione (GSH) became sensitive to tumor necrosis factor- or UV light-induced activation of AP24 and underwent apoptotic cell death. Moreover, nuclei isolated from Bcl-2-overexpressing cells that were depleted of GSH became sensitive to AP24-induced DNA fragmentation. The addition of exogenous GSH blocked the proteolytic activity of AP24, as well as its ability to induce DNA fragmentation in normal isolated nuclei. These results indicate that Bcl-2 can attenuate at least two events in the AP24 apoptotic pathway: activation of AP24 and induction of DNA fragmentation by activated AP24. Furthermore, agents that deplete intracellular levels of GSH may have therapeutic use in the sensitization of Bcl-2-overexpressing cancer cells to apoptotic cell death.

Apoptosis↗

PubMed1998

Chemotherapeutic drug activation of the AP24 protease in apoptosis: requirement for caspase 3-like-proteases.

AP24 is a serine protease that is activated during TNF or UV light-induced apoptosis and stimulates DNA fragmentation in isolated nuclei. The present study determined whether apoptosis induced by chemotherapeutic drugs resulted in activation of AP24 and examined the possible relationship to caspase activity. We showed that an inhibitor of AP24, DK120, could block DNA fragmentation induced in three leukemia cell lines (U937, HL-60, and CEM) by various DNA-damaging drugs including etoposide, camptothecin, chlorambucil, and the CC1065-related drug, YW201. Etoposide-induced activation of intracellular DEVD-pNa cleaving activity and apoptosis was suppressed by low micromolar concentrations of cell-permeable inhibitors of caspase-3. Furthermore, these inhibitors also suppressed activation of AP24. In contrast, DK120 did not prevent etoposide activation of DEVD-pNa cleaving activity, nor did it prevent cleavage of poly(ADP-ribose) polymerase. AP24 isolated from apoptotic cells following treatment with etoposide activated DNA fragmentation in isolated normal nuclei and was inhibited by DK120, but not by caspase inhibitors. This evidence shows that activation of caspase 3-like proteases generates signals that contribute to the activation of AP24 which may then induce nuclear DNA fragmentation in chemotherapeutic drug-induced apoptosis.

Antineoplastic Agents, Phytogenic↗

PubMed1998

Autoinducer of virulence as a target for vaccine and therapy against Staphylococcus aureus.

Staphylococcus aureus causes pathologies ranging from minor skin infections to life-threatening diseases. Pathogenic effects are largely due to production of bacterial toxin, which is regulated by an RNA molecule, RNAIII. The S. aureus protein called RAP (RNAIII activating protein) activates RNAIII, and a peptide called RIP (RNAIII inhibiting peptide), produced by a nonpathogenic bacteria, inhibits RNAIII. Mice vaccinated with RAP or treated with purified or synthetic RIP were protected from S. aureus pathology. Thus, these two molecules may provide useful approaches for the prevention and treatment of diseases caused by S. aureus.

Amino Acid Sequence↗

PubMed1998

Case report: postconcussion syndrome after minor head injury.

A 31-yr-old flight medic struck the top of his head while loading a patient onto an ambulance. He sustained a momentary alteration of sensorium but otherwise seemed fine. Approximately 1 week after the incident, he experienced the onset of headaches and disabling vertigo that persisted over the next 2 mo, gradually decreasing in severity with time. Although not deemed significant at the time of injury, a mild head injury can result in postconcussion syndrome, a collection of neurologic symptoms that can persist for some time before resolving. This case emphasizes the need for a period of observation after head trauma before clearing aviators for flying duties.

Adult↗

PubMed1997

Activation of CPP32-like proteases is not sufficient to trigger apoptosis: inhibition of apoptosis by agents that suppress activation of AP24, but not CPP32-like activity.

The 24-kD apoptotic protease (AP24) is a serine protease that is activated during apoptosis and has the capacity to activate internucleosomal DNA fragmentation in isolated nuclei. This study examined the following: (a) the functional relationship between AP24 and the CPP32-like proteases of the caspase family; and (b) whether activation of CPP32-like proteases is sufficient to commit irreversibly a cell to apoptotic death. In three different leukemia cell lines, we showed that agents that directly (carbobenzoxy-Ala-Ala-borophe (DK120) or indirectly inhibit activation of AP24 (protein kinase inhibitors, basic fibroblast growth factor, tosylphenylalaninechloromethylketone, and caspase inhibitors) protected cells from apoptosis induced by TNF or UV light. Only the caspase inhibitors, however, prevented activation of CPP32-like activity as revealed by cleavage of the synthetic substrate, DEVD-pNa, by cell cytosols, and also by in vivo cleavage of poly (ADP-ribosyl) polymerase, a known substrate of CPP32. Activation of DEVD-pNa cleaving activity without apoptosis was also demonstrated in two variants derived from the U937 monocytic leukemia in the absence of exogenous inhibitors. Cell-permeable peptide inhibitors selective for CPP32-like proteases suppressed AP24 activation and apoptotic death. These findings indicate that CPP32-like activity is one of several upstream signals required for AP24 activation. Furthermore, activation of CPP32-like proteases alone is not sufficient to commit irreversibly a cell to apoptotic death under conditions where activation of AP24 is inhibited.

Apoptosis↗

PubMed1997

Tumor cell endocytosis imaging facilitates delineation of the glioma-brain interface.

We describe a method for measuring tumor cell endocytosis in vivo and provide the anatomic correlate of this tumor cell function using a superparamagnetic and histologically detectable marker for cell uptake (MION). Rats (n = 22) were intrahemispherically implanted with a thymidine kinase (TK)-positive 9L gliosarcoma cell line, where TK served as the tumor marker. Twenty-four hours after intravenous injection of 10 mg Fe/kg of MION, rat brains were removed and underwent MR imaging ex vivo at near-microscopic resolution (isotropic voxel size of 86 microm, 9.4 T) prior to histologic processing. The imaging probe accumulated within tumor cells adjacent to the hyperpermeable tumor-brain interface including microscopic deposits and along finger-like invasions of the tumor into brain, facilitating the demarcation of the true histologic tumor border in three dimensions by MR microscopy. The method has potential research and clinical implications for delineating the tumor-brain interface prior to therapy and/or for providing a rational basis for imaging nanocolloid drug delivery to solid tumors.

Animals↗

PubMed1997

Calmodulin-dependent protein kinase II mediates signal transduction in apoptosis.

The present studies describe a new function for calmodulin-dependent protein kinase II (CaM-KII) in signal transduction leading to apoptosis. Both tumor necrosis factor alpha (TNF) and UV light rapidly stimulated Ca2+-independent activity of CaM-KII in the monocytic leukemia, U937. Two mechanistically different inhibitors of CaM-KII blocked activation of CaM-KII and prevented DNA fragmentation and death. Activation of CaM-KII during apoptosis and inhibition of DNA fragmentation by the two CaM-KII inhibitors were reproduced in several other lines including KGla, HL-60, and YAC-1. However, K562, which is relatively resistant to apoptosis induced by either TNF or UV light, did not activate CaM-KII in response to these stimuli. A variant derived from U937 that is resistant to TNF- or UV light-induced apoptosis also lacked a CaM-KII response. Activation of Cam-KII was blocked by two protease inhibitors, VAD-fmk and TPCK, but not by other inhibitors of serine proteases. Both inhibitors of CaM-KII and the protease inhibitors blocked activation of AP24, a serine protease originally isolated from apoptotic cells that induces DNA fragmentation in nuclei. Our evidence supports a model in which proteolytic activity functions upstream of CaM-KII. This kinase then leads to activation of AP24, which transmits signals to the nucleus to initiate DNA fragmentation.

Apoptosis↗

PubMed1997

A long-circulating co-polymer in "passive targeting" to solid tumors.

A co-polymer of O-methyl polyethylene(glycol)-O'-succinate (MPEGs, m.w. 5100) and poly-l-lysine (PL, median m.w. 32700, degree of polymerization 256) has been synthesized by covalent grafting. The resultant MPEGs-PL (30% modification degree of epsilon-amino groups) had a hydrodynamic diameter corresponding to a 690 kD protein. Free amino groups (180/mol of the co-polymer) were used for conjugation of diethylene pentaacetic or succinic acid residues to MPEGs-PL. The potential of the resultant compound as a carrier of therapeutic and diagnostic drugs was studied using a rodent carcinoma models. The co-polymer had a blood pool half-life of 36h in adenocarcinoma-bearing rats. Radioactively labeled preparations were resistant to trans-chelation with apotransferrin and stable in blood for 24 h. The co-polymer accumulated in solid tumors at the level of 1.5-2% injected dose/g of tumor in 24 h. At that time, 34-40% of the accumulated polymer was associated with tumor cell fraction. The co-polymer non-covalently associated with cis-diamminedichloroplatinum(II), showed a cytostatic effect against mouse F9 carcinoma, and induced a reversal in tumor growth after intravenous administration.

Animals↗

PubMed1996

Structural, functional analysis and localization of the human CAP18 gene.

CAP18 is an antimicrobial protein found in specific granules of PMNs. The human CAP18 (HCAP18) gene was cloned from a human genomic phage library. Sequence analysis revealed the HCAP18 gene to have 4 exons spanning 3 kb, including 700 bp of upstream DNA. Using 3' RACE no homologs of human HCAP18 were found in human bone marrow or leukocyte populations. By PCR analysis of a somatic cell mapping panel and fluorescence in situ hybridization of a genomic clone to metaphase chromosomes the gene was mapped to chromosome band 3p21.3. Like several other genes expressed late in PMN development the CAP18 gene did not contain typical TATA box or CCAAT sequences. Expression in Cos 7 cells permitted limited mapping of the promoter function in upstream fragments of the HCAP18 gene. Western blot, Northern blot and RT-PCR analysis show HCAP18 to be produced specifically in granulocytes. This work forms the groundwork for future analysis of the genetic regulation of this antimicrobial protein during PMN differentiation.

Antimicrobial Cationic Peptides↗

PubMed1996

Biochemical pathways of apoptosis: nicotinamide adenine dinucleotide-deficient cells are resistant to tumor necrosis factor or ultraviolet light activation of the 24-kD apoptotic protease and DNA fragmentation.

The function of nicotinamide adenine dinucleotide (NAD) and adenosine diphosphate (ADP) ribosylation reactions in the mechanism of apoptotic cell death is controversial, although one theory postulates an essential role for NAD depletion by poly-ADP-ribose polymerase. The present study examined the role of intracellular NAD in tumor necrosis factor (TNF) and ultraviolet (UV) light-induced activation of the 24-kD apoptotic protease (AP24) leading to internucleosomal DNA fragmentation and death. Our results demonstrate that nutritional depletion of NAD to undetectable levels in two leukemia lines (U937 and HL-60) renders them completely resistant to apoptosis. This was attributed to a block in the activation of AP24 and subsequent DNA cleavage. Normal cells show an elevation of ADP-ribosyl transferase (ADPRT) in both the cytosol and nucleus after exposure to TNF, but before DNA fragmentation. ADPRT activity as well as cell death was suppressed by an inhibitor specific for mono-ADPRT. Nuclei from NAD-depleted cells were still sensitive to DNA fragmentation induced by exogenous AP24, indicating a selective function for NAD upstream of AP24 activation in the apoptotic pathway. We confirmed a requirement for intracellular NAD, activation of ADPRT, and subsequent NAD depletion during apoptosis in KG1a, YAC-1, and BW1547 leukemia cell lines. However, this mechanism is not universal, since BJAB and Jurkat leukemia cells underwent apoptosis normally, even in the absence of detectable intracellular NAD. We conclude that TNF or UV light-induced apoptotic cell death is not due to NAD depletion in some leukemia cell lines. Rather, NAD-dependent reactions which may involve mono-ADPRT, function in signal transduction leading to activation of AP24, with subsequent DNA fragmentation and cell death.

3-Iodobenzylguanidine↗

PubMed1996

Enhanced resolution of proton NMR spectra of malignant lymph nodes using magic-angle spinning.

Proton NMR spectroscopy has proven useful in the detection of cancer in lymph node tissue. However, due to the high fat content of this type of tissue, 2D 1H COSY measurements (requiring acquisition times of 4-5 h or longer) are necessary to obtain the spectral information necessary for diagnosis. T2-filtered proton magic-angle spinning (MAS) NMR spectroscopy provides 1D spectra of lymph nodes in approximately 20 min with sufficient spectral resolution allowing for identification of changes in cellular chemistry due to the presence of malignant cells. MAS data from lymph nodes of five control and six rats with mammary adenocarcinoma (R13762) demonstrated increases in the signal intensity of resonances associated primarily with lactate (delta = 4.12 ppm) P < 0.0004, creatines/lysine (delta = 3.04 ppm) P < 0.0032, and glutamate/ glutamine (delta = 2.36 ppm) P < 0.0002 in metastatic compared with normal lymph nodes. The infiltration of lymph nodes by malignant cells is an important prognostic factor for many cancers. The rapid assessment of node tissue without the introduction of sampling errors (inherent in currently employed histological procedures) would allow postoperative therapy decisions to be made more efficiently.

Adenocarcinoma↗

PubMed1996

Tumor cell resistance to apoptosis due to a defect in the activation of sphingomyelinase and the 24 kDa apoptotic protease (AP24).

Signal transduction pathways involved in apoptotic cell death are poorly understood, although recent studies have implicated sphingomyelin hydrolysis and generation of the second messenger, ceramide. Previous work in this laboratory demonstrated that a serine protease termed AP24 was activated by TNF or UV light and induced DNA fragmentation in isolated nuclei. This study extended these findings to examine the role of these enzymes in apoptosis of the U937 cell line and the mechanism of resistance of its variant, U9-TR. Although this subclone was selected by growth in TNF, it was unexpectedly found to resist apoptosis induced by UV light, but was still sensitive to anti-Fas-induced DNA fragmentation. Here we show that in contrast to normal U937 cells, UV light and TNF both failed to activate neutral or acidic sphingomyelinase or AP24 in the U9-TR variant. However, anti-Fas activated both neutral and acidic sphingomyelinase in the variant comparable to that seen in parental U937. The U9-TR variant could be sensitized to TNF or UV light activation of both sphingomyelinase and DNA fragmentation by the protein phosphatase inhibitors okadaic acid and calyculin A. Furthermore, exogenous bacterial-derived sphingomyelinase caused U9-TR activation of AP24 and DNA fragmentation comparable to that in the parental U937. Exposure of permeabilized U937 cells to ceramide caused internucleosomal DNA cleavage that was blocked by an inhibitor of AP24. Taken altogether, these findings demonstrate that TNF or UV light activate sphingomyelinase that leads to the generation of ceramide resulting in activation of AP24 and DNA fragmentation in sensitive cells. A selective defect in signals leading to sphingomyelinase activation can confer resistance to apoptosis even though the variant is still sensitive to downstream apoptotic signals such as nuclear DNA fragmentation by activated exogenous AP24.

Apoptosis↗

PubMed1996

Death from airways obstruction: accuracy of certification in Northern Ireland.

BACKGROUND: Studies of mortality from asthma and chronic obstructive pulmonary disease (COPD) have relied on death certification or registration for case finding. The aim of this study was to determine the accuracy of death certification and registration in asthma and COPD. METHODS: All death certificates in Northern Ireland for 1987 where asthma or COPD (defined as International Classification of Diseases 9th Revision (ICD9) 490, 491, 492, 496) were listed in part I or part II were identified. The following certificates were then selected for further investigation: those mentioning asthma for all ages, those mentioning COPD for ages less than 56 years, and a 50% sample of those mentioning COPD aged 56-75 years. For these selected deaths the general practitioners' case notes, hospital records, and necropsy findings were reviewed. Questionnaires detailing the clinical history and circumstances of death were completed by the general practitioner by post and by a close relative or associate of the deceased (doctor administered) if, after initial investigation, the death was likely to be due to COPD or asthma. A panel of two respiratory physicians reviewed each death and, using clinical diagnostic criteria, assessed the accuracy of the registered cause of death. RESULTS: Of 50 registered asthma deaths 43 were confirmed as being due to asthma. In nine registered deaths from COPD in cases aged less than 56 years one was confirmed as COPD, two as asthma, and six as other respiratory conditions. Of 105 registered deaths from COPD in cases aged 56-75, 42 were confirmed as COPD, 27 as asthma, eight as other respiratory conditions, and 28 as other causes. Although few errors in registration were found, 21% of certificates mentioning asthma and 38% of certificates mentioning COPD but not asthma in part I were subject to variable application of the classification rules by the registering officers. For all deaths under 75 years of age in Northern Ireland in 1987 where either asthma or COPD was mentioned anywhere on the death certificate, the estimated sensitivity and specificity of the registered cause of death in predicting the "true" cause of death were 29% and 98.6% for asthma and 69% and 70% for COPD. CONCLUSIONS: In a population of subjects where asthma or COPD was mentioned anywhere on the death certificate, the registered cause of death is a relatively poor indicator of the "true" cause of death for both asthma and COPD. Variation occurred in the application of death classification rules by registration officers. Many deaths certified and registered as COPD could have been called asthma using current standards of clinical diagnosis. In studies investigating risk factors for deaths from asthma, case finding should consider deaths registered as COPD.

Aged↗