PubMed Health⌕ Search

Biomedical subjects

D Ratcliffe

Publications and source records attributed to D Ratcliffe.

At least 19 recordsLinked to original sources
PubMed2005

Emergence and evolution of enfuvirtide resistance following long-term therapy involves heptad repeat 2 mutations within gp41.

The objective of this study was to track the evolution of sequence changes in both the heptad region 1 (HR1) and HR2 domains of gp41 associated with resistance to enfuvirtide (ENF) in a patient cohort receiving long-term ENF treatment. We studied 17 highly antiretroviral agent-experienced patients receiving long-term ENF treatment with virological rebound or a lack of suppression. Sixty-two samples obtained after between 5 and 107 weeks of ENF therapy were analyzed. Baseline samples from 15 of these 17 patients were available for analysis. Viruses from five samples from four patients were also sequenced after the cessation of ENF therapy. Drug susceptibilities were assessed by a pseudotype virus reporter assay. We identified HR1 and HR2 sequence changes over time in relation to the baseline sequences. Mutations in HR1 (amino acids 36 to 45) were noted in all cases, including previously unreported changes N42Q/H and N43Q. In addition to a range of HR2 sequence changes at polymorphic sites, isolates from 6 of 17 (35%) patients developed an S138A substitution in the HR2 domain at least 8 weeks after the start of ENF treatment and also subsequent to the first emergence of HR1 mutations. In most, but not all, cases the S138A mutation accompanied HR1 mutations at position 43. Molecular modeling demonstrates the close proximity of S138A with amino acids 40 and 45 in HR1. Of note, isolates in samples available from four patients demonstrated the loss of both the HR1 and the S138A HR2 mutations following the cessation of therapy. We show that the S138A HR2 mutation increased the level of resistance by approximately threefold over that conferred by the HR1 mutation N43D. Continual evolution of HR1 in the domain from amino acids 36 to 45 was observed during long-term ENF therapy. We have identified, for the first time, an ENF resistance-associated HR2 mutation, S138A, which appeared in isolates from 6 of 17 patients with virological failure and demonstrated its potential to contribute to drug resistance. We propose that this represents a possible secondary and/or compensatory mutation, particularly when it coexists with mutations at position 43 in HR-1.

Amino Acid Sequence↗
PubMed2001

Failure of combination therapy with lamivudine and famciclovir following lamivudine monotherapy for hepatitis B virus infection in patients coinfected with human immunodeficiency virus-1.

Individuals coinfected with human immunodeficiency virus 1 (HIV-1) and hepatitis B virus (HBV) often receive treatment with an antiretroviral regimen including lamivudine. Lamivudine monotherapy for HBV may lead to drug-resistant mutations in a significant number of patients. The virological and biochemical responses of 8 patients coinfected with HBV/HIV-1 treated with both lamivudine and famciclovir were studied. Patients exhibiting HBV viral rebound at 1 year were analyzed for the emergence of HBV polymerase mutations. Only 1 patient had no prior exposure to lamivudine. Addition of famciclovir to the treatment regimen resulted in a median fall in HBV DNA level of 0.33 log(10) at 3 months and an overall rise in HBV DNA level of 3 log(10) at 12 months. The only patient in whom durable viral suppression and HBV e antigen seroconversion were noted began receiving lamivudine and famciclovir simultaneously. HBV polymerase gene sequencing identified resistance-associated mutations in 6 of 7 patients with viral rebound. Sequential nucleoside analogue therapy is unlikely to be successful in achieving long-term suppression of HBV replication, and combination therapy should be considered at treatment initiation.

2-Aminopurine↗
PubMed2001

Psychiatric morbidity and its recognition by doctors in patients with cancer.

Psychiatric morbidity in patients with cancer is high and without appropriate treatment unremitting. We assessed the ability of 143 doctors to establish the psychological status of 2297 patients during outpatient consultations in 34 cancer centres and hospitals in the UK. Prior to seeing the doctor, consenting patients completed a short self-report questionnaire (GHQ12), designed for the psychological screening of large populations. At the end of the consultation, doctors completed visual analogue scales rating patients' distress. 837/2297 (36.4%) patients had GHQ scores suggestive of psychiatric morbidity. The doctors' sensitivity (true positive rate) was 28.87% (SD 25.29), specificity (true negative rate) 84.79% (SD 17.44). The misclassification rate was 34.7% (SD 13.79) meaning that for 797 patients the wrong assessment was probably made. These data show that much of the probable psychiatric morbidity experienced by patients with cancer goes unrecognized and therefore untreated. Doctors need communication skills training to elicit problems during consultations. Appropriate referrals to psychological services are necessary when patients requiring help are identified and ought to be an integral part of cancer care.

Adult↗
PubMed2000

Evolution of lamivudine-resistant hepatitis B virus and HIV-1 in co-infected individuals: an analysis of the CAESAR study. CAESAR co-ordinating committee.

OBJECTIVES: Lamivudine has potent activity against HIV-1 and hepatitis B virus (HBV). Co-infection with these two viruses is common, and this may therefore influence the choice of antiretroviral therapies. A cohort of co-infected patients treated with lamivudine were studied in order to evaluate the differential effects of lamivudine on the two viral populations within the same individual after 44-52 weeks of therapy. DESIGN AND METHODS: Retrospective virological analysis of an HIV-1/HBV co-infected lamivudine cohort derived from a randomized, placebo-controlled study of lamivudine in HIV infection, the CAESAR study. RESULTS: Five of thirteen patients with HBV viral load > 10,000 copies/ml after 44-52 weeks of lamivudine therapy had genotypic drug resistance. Four of these five had a rebound of viral replication over the period of study and in one case this was associated with an alanine transaminase serum elevation. Ten of the thirteen patients had a 44-52 week HIV viral load > 1000 copies/ml, all of whom also had HIV reverse transcriptase M184V or M184I mutations. CONCLUSIONS: Extrapolating these results to the population yields an estimated 1-year incidence of drug-resistant HBV of at least 14% in lamivudine-treated HIV-1/HBV co-infected patients. The clinical and virological benefit of HBV lamivudine monotherapy in co-infected patients should be balanced against the potential for emergence of drug resistance. Further, these data suggest that the determinants of HIV and HBV drug resistance are different and that parallel evolution, rather than co-evolution of HBV and HIV-1 in co-infected individuals occurs.

CD4 Lymphocyte Count↗
PubMed2000

Resistance to antiviral drugs in herpes simplex virus infections among allogeneic stem cell transplant recipients: risk factors and prognostic significance.

Herpes simplex virus (HSV) infections in 75 allogeneic stem cell transplant recipients were analyzed. Sixteen patients developed HSV disease following transplantation. The risk factors were age, sex (females), unrelated donor graft, and graft-versus-host disease (GVHD) grade >/=2. Seven patients did not respond to acyclovir, and 3 patients failed to respond to foscarnet. Isolates from 4 patients developed resistance to acyclovir/penciclovir, and 3 patients had foscarnet-resistant isolates. The remaining 3 patients failed to respond to acyclovir, despite having sensitive isolates. All the isolates were sensitive to cidofovir, for which the IC(50) values correlated inversely with those for acyclovir (P=.01). The risk factors for clinical resistance to antiviral drugs were a GVHD grade >/=2 (P=.001) and the lack of ganciclovir prophylaxis (P=.01), with a higher nonrelapse mortality in the latter group (P<.0001). Clinical as well as in vitro resistance to antiviral drugs is common in patients with severe GVHD and is associated with a poor outcome.

Acyclovir↗
PubMed2000

The Medical Interaction Process System (MIPS): an instrument for analysing interviews of oncologists and patients with cancer.

The increase in communication skills training for doctors has led to the need for more effective means of evaluation. Analysis of video and audiotaped consultations using systems of interaction analysis can provide the trainee with in-depth feedback about their communication skills. Most interaction process systems were designed for use in primary care and recent research has questioned the applicability of these systems in medical specialties such as oncology. We describe the development of a new instrument, the Medical Interaction Process System (MIPS) for use in teaching communication skills and empirical research in medical encounters, particularly, between doctors and patients with cancer. A comparison of the MIPS and comparable behaviour categories of another widely used system (the Roter Interaction Analysis System) was made to test convergent validity. Pearson correlation coefficients suggested a good level of concurrence between the two systems. Intercoder reliability tests were carried out between two coders at two separate time periods. Both of these indicated good reliability for the majority of categories. The two major advantages of the MIPS over other coding systems are: (1) the system allows for sequential and parallel coding, thus avoiding major coding conflicts and (2) the design of the coding sheet results in a multidimensional view of the consultation without data loss. We believe that the MIPS yields useful information for teaching doctors communication skills and also provides an objective method for evaluating the effectiveness of communication skills courses.

Humans↗
PubMed2000

Selection of multiresistant hepatitis B virus during sequential nucleoside-analogue therapy.

Hepatitis B virus (HBV) drug resistance to lamivudine is always accompanied by mutations in the viral polymerase gene at position 550, termed group 1 (M550V with L526M) or group 2 (M550I) mutations. The latter mutation has not been associated with famciclovir resistance. Thus, the addition of famciclovir to lamivudine therapy in persons with group 2 lamivudine resistance may lead to virus suppression. The effect of lamivudine/famciclovir combination therapy on HBV infection was monitored in 5 lamivudine-resistant patients by quantitative polymerase chain reaction and polymerase gene sequencing of serum virus. No patients treated with combination therapy had a decline in HBV load >1 log10. Continual evolution of the viral polymerase was detected in association with virologic resistance to both drugs. Cloning experiments identified the preexistence of these multidrug-resistant virus variants as minority species prior to addition of famciclovir therapy. HBV resistance to lamivudine monotherapy is associated with a complex mixture of variants that limit the efficacy of second-line nucleoside-analogue therapy. First-line potent combination therapy may reduce the emergence of HBV drug resistance.

2-Aminopurine↗
PubMed2000

Outcome of lamivudine resistant hepatitis B virus infection in the liver transplant recipient.

BACKGROUND: In many transplant centres lamivudine is an important component of prophylaxis against, and treatment of, hepatitis B virus (HBV) graft infection. Drug resistant HBV species with specific polymerase mutations may emerge during lamivudine treatment. AIMS: To examine the clinical consequences of graft infection by lamivudine resistant virus. METHODS: The clinical course of four liver transplant patients who developed graft infection with lamivudine resistant virus was reviewed. The response of HBV infection to reduction of immunosuppression and to manipulation of antiviral therapy was assessed. For each patient, serum viral titre was measured and the viral polymerase gene was sequenced at multiple time points. RESULTS: High serum titres were observed following emergence of the lamivudine resistant species. Wild type HBV re-emerged as the dominant serum species after lamivudine withdrawal. All patients developed liver failure, and onset of liver dysfunction was observed when resistant virus was the dominant serum species. In three patients, liver recovery was observed when immunosuppression was stopped and when alternative antivirals were given. Wild type virus appeared to respond to ganciclovir, and to reintroduction of lamivudine. For one patient, introduction of famciclovir was associated with clinical, virological, and histological response. CONCLUSIONS: Failure of lamivudine prophylaxis may identify patients at special risk for the development of severe graft infection. Treatment of graft reinfection should include reduction of immunosuppression, and systematic exposure to alternative antivirals. Viral quantitation and genetic sequencing are essential components of therapeutic monitoring.

Adult↗
PubMed2000

Additive antiviral effects of lamivudine and alpha-interferon in chronic hepatitis B infection.

alpha-Interferon has limited efficacy against chronic hepatitis B virus (HBV) infection. Nucleoside analogues may confer greater benefits, however, it is likely that combination therapies will be required for effective control of this infection. We investigated the antiviral effect of lamivudine and interferon therapy in eight patients with high HBV-DNA levels. Six patients received lamivudine/interferon combination therapy followed, after a 6-month drug-free period, with lamivudine monotherapy. Mean HBV viral load (copies/ml) reduction was significantly greater after 4 months of combination therapy (4.3 x 10(3)) compared to an equivalent period of lamivudine monotherapy (2.9 x 10(2)) (P=0.03). Two patients were given 6 months of lamivudine/interferon combination therapy followed immediately by lamivudine monotherapy. Cessation of interferon in these patients led to a rapid 1-2 log10 increase in HBV viral load. These findings suggest that alpha-interferon has a direct antiviral effect on chronic HBV infection, which may be additive to, or synergistic with lamivudine.

Antiviral Agents↗
PubMed1999

Use of real-time PCR and fluorimetry to detect lamivudine resistance-associated mutations in hepatitis B virus.

Very rapid amplification of DNA by PCR in small volumes can be continuously monitored by the detection of the binding of probes with a rapid cycler with built-in fluorometric detection. Primers were designed to amplify approximately 100 bp of the polymerase gene of hepatitis B virus (HBV) spanning codon 550, where mutations associated with resistance to lamivudine invariably occur. Four hybridization probes were synthesized: one was 3' labelled with fluorescein and hybridized upstream of codon 550. The others were 5' labelled with Cy5 and 3' labelled with biotin and spanned codon 550. The Cy5-labelled oligonucleotides contained either wild-type (ATG) or mutant (GTG or ATT) sequences. A Cy5-labelled probe and either the fluorescein-labelled probe or Sybr Green 1 (a compound that fluoresces when bound to double-stranded DNA) were included in each PCR. After completion of the amplification by using a LightCycler (Idaho Technology), the temperature at which the Cy5 probe melted from the product was determined in a melt program that took ca. 3 min. Pre- and posttreatment samples from eight patients (five chronic and three transplant) who failed lamivudine treatment were amplified, and the presence of mutations in codon 550 was determined by ABI sequencing and by using the LightCycler; in some cases PCR products were also cloned, and multiple clones were sequenced. Concordant results were obtained in all cases. We found the LightCycler to be better at resolving the sequences of genomic mixtures; for example, two samples showed a sequence at codon 550 of (A/G)T(G/T), which was found by fluorimetry to be mixtures of GTG and ATT but no ATG, and this finding was confirmed by the sequencing of clones. However, this approach was not more sensitive than population sequencing for the detection of the presence of mixtures. Overall, this pilot study has demonstrated an approach that could be an extremely rapid and economical method for the detection of lamivudine resistance-associated mutations in HBV.

Anti-HIV Agents↗
PubMed1999

Analysis of hepatitis B virus quasispecies changes during emergence and reversion of lamivudine resistance in liver transplantation.

This report describes nucleotide sequence analysis of part of the polymerase gene of hepatitis B virus (HBV) during the development of lamivudine-resistant HBV in five patients who received lamivudine treatment in conjunction with liver transplantation. Samples from patients were analysed before, during and after drug treatment in conjunction with serum HBV quantification by PCR. Lamivudine resistance was found to be associated with L526M and M550V changes in two patients and M550I change in three patients. Other changes associated with lamivudine resistance in some patients were V509I, A546V, S565A and A568T. The effects on HBV surface antigen are also described. Some patients were subsequently treated with famciclovir and/or ganciclovir with variable outcomes. In two out of three patients who stopped lamivudine treatment, reversion (partial or complete) to wild-type virus was observed after about 5 months. In contrast, a complex mixture of mutant viruses emerged in a third patient who stopped lamivudine treatment.

Antiviral Agents↗
PubMed1997

Clinicians' attitudes to clinical trials of cancer therapy.

Progress in the assessment and introduction of new treatments is impeded by the failure to recruit eligible patients into clinical trials. Little is known about the attitudes of U.K. cancer specialists towards trial participation, therefore a postal survey was conducted of 553 British clinical, medical and surgical oncologists. A 45-item questionnaire was returned by 357 clinicians (65% response rate). Although 353 (99%) of respondents stated that they were participating in trials, median 3 (range 0-62), 269 (75%) of clinicians were entering fewer than 50% of eligible patients. Differences were seen between professional groups within oncology; medical oncologists placed more emphasis on research than on clinical activities, felt greater pressure to participate in trials and were more likely to value being known by national and international colleagues than did surgeons or clinical oncologists. Surgeons were more likely to rely on clinical experience rather than enter patients into a trial but were more likely to keep patients on study following relapse. The survey identified constraints imposed by the healthcare system which impede trial participation including lack of time, communication difficulties and conflicts between the role of clinician and scientist. Such factors need consideration when trials are designed. Comparison of British data with those from the U.S. clinicians were broadly similar. The few differences found suggest that the more protocol-driven culture of the U.S. might encourage recruitment and a greater commitment to keep patients on trials.

Attitude of Health Personnel↗
PubMed1994

Viral hepatitis in Nigeria--sickle-cell disease and commercial blood donors.

Hepatitis virus infection is a major cause of morbidity and mortality in sub-Saharan Africa. The high prevalence of hepatitis B virus (HBV) infection in this region is thought to be due to horizontal transmission during childhood. Hepatitis C virus (HCV) infection is also quite prevalent in Africa, but the epidemiology of this infection has yet to be defined. We examined the prevalence of HBV and HCV serological markers in 220 patients attending sickle-cell anaemia clinics in Benin City, Nigeria, in 228 healthy locals, and in 104 local commercial blood donors, to test the hypothesis that patients requiring blood transfusion from unscreened commercial blood donors (in this area of high prevalence for viral hepatitis) are at great risk for the acquisition of post-transfusion hepatitis. Overall, the frequency of hepatitis viraemia in blood donors was high (14% of donors were either HbsAg or anti-HCV positive). Evidence of previous exposure to HBV was common in all three study groups. Risk of HBV infection for sickle-cell patients was not clearly increased by blood transfusion. HCV exposure, however, appears related to transfusion requirement, and all Western-blot-confirmed anti-HCV-positive sicklers had a history of blood transfusion. Screening of blood products in sub-Saharan Africa is unlikely to reduce prevalence of HBV, but may minimize the risks of HCV transmission.

Adolescent↗
PubMed1993

Characterization of influenza virus-induced leukocyte adherence to human umbilical vein endothelial cell monolayers.

The adherence of undifferentiated 51Cr-labeled HL-60 (0.5 x 10(6) HL-60 cells/well) cells was monitored on influenza virus-infected HUVEC monolayers. Whereas only 3.0 +/- 1.6% (n = 36) of HL-60 cells adhered to uninfected HUVEC, adherence was increased to 41.7 +/- 2.2% (n = 6), 79.7 +/- 1.2% (n = 6), 83.9 +/- 0.7% (n = 6), and 84.4 +/- 0.5% (n = 6) on HUVEC infected for 7 h at a MOI of 1, 3, 6, and 9, respectively. In comparison, HL-60 cell adherence increased to 35% when HUVEC monolayers were stimulated with LPS (0.2-20 micrograms) for 4 h. Increased adherence to infected HUVEC occurred at 5 h postinfection, peaked at 7 h, and was maintained at 24 h postinfection. Active virus and metabolically active endothelial cells were required to mediate the virus-induced adherence. E-selectin and ICAM-1 Ag were upregulated 78.3- and 4.1-fold, respectively, by LPS (0.02-20 micrograms, 4 h) whereas virus infection (7 h) only increased these proteins 2.6- and 1.4-fold with a MOI > or = 16. Although the time courses of expression for both adhesion molecules after LPS treatment of virus infection were similar, the difference in the magnitude of upregulation suggests that virus-induced adherence is not a result of upregulation of E-selectin and ICAM-1. In contrast, surface expression of HA is involved in HL-60 cell adherence to virus-infected HUVEC because (1) the time course and magnitude of HA AG expression paralleled the time course and magnitude of HL-60 cell adherence after virus infection of HUVEC; (2) HL-60 cell aggregates were absent on infected HUVEC monolayers in the presence of anti-HA; (3) HL-60 cells competed with RBC for infected endothelial cells stained for cellular HA Ag and (4) anti-HA abolished the virus-induced adherence. Furthermore, it appears that HL-60 cells are binding directly to HA because HL-60 cell adherence to a cell-free surface was increased if virus was prebound and neuraminidase treatment of HL-60 cells prevented the HL-60 cell adherence to influenza virus-infected endothelial monolayers.

Cell Adhesion↗
PubMed1993

Antenatal survey for the seroprevalence of HTLV-1 infections in the West Midlands, England.

The sera of 3522 women who attended an antenatal clinic in Birmingham, England were tested anonymously for antibodies against HTLV-1. Samples from 5 women (0.14%) were positive, one serum showed indeterminate reactivity. Two of the women (0.06%) were born in the West Indies (of Afro-Caribbean ethnic origin), one (0.03%) in Africa (of African ethnic origin), and three (0.09%) were white Caucasian women born in the UK. Thus, HTLV-1 infection in pregnant women in the UK, though comparatively rare, is not negligible. As transmission of HTLV-1 to the newborn via breast milk has been observed and as seropositive mothers can be advised to refrain from breastfeeding or to treat their milk, the question of routine screening for HTLV-1 infection during antenatal care is discussed.

Adolescent↗
PubMed1992

Translocation of influenza virus by migrating neutrophils.

Influenza, a predominantly upper respiratory tract infection, replicates in the respiratory epithelia and spreads by an unknown mechanism to the regional lymph nodes. Neutrophils, which accumulate during the early stages of the infection, may be involved in this process. An in vitro model system was used to examine the effect of migrating neutrophils on the permeability of the infected epithelium and on the spread of virus. Epithelial cells (MDCK) infected with influenza virus (WSN H1N1) maintained a stable transepithelial electrical resistance (a measure of epithelial permeability) for 12 hrs. However, when neutrophils migrated across the epithelium toward the virus budding on the apical surface of the epithelium (6 hrs. after infection), the transepithelial electrical resistance fell 24% (P less than 0.001). Neutrophils adhered specifically to the virus and to hemagglutinin expressed exclusively on the apical surface of the cells and phagocytized the free virions. In response to a chemotactic gradient, the infected neutrophils were able to leave the lumenal surface of the infected epithelium, and were able to migrate across the epithelium in equal numbers and at the same rate as uninfected neutrophils. Migration across infected monolayers from the lumenal to the ablumenal surface also caused a fall in resistance (21%, P less than 0.01). Electron microscopic examination of emigrating neutrophils revealed that the leukocytes transported the influenza virions within phagocytic vacuoles and on their surface to the ablumenal side of the monolayer. The results of these studies suggest that the passage of leukocytes across influenza-infected epithelia increases the permeability of the epithelium and provides a route for viral spread.

Animals↗
PubMed1984

Failure of transdermal nitroglycerin to improve chronic stable angina: a randomized, placebo-controlled, double-blind, double crossover trial.

We assessed the effect of transdermal nitroglycerin (NTG-TTS), releasing 5 mg/24 hr, in 11 patients with chronic stable angina during a randomized, placebo-controlled, double-blind, double crossover trial of four 1-week periods. All patients had a positive exercise test and coronary artery disease prior to entry into the study. Efficacy was assessed weekly by anginal diaries, ambulatory ST segment recordings, and computerized exercise testing 2 to 4 hours after renewal of NTG-TTS. One patient withdrew in the first week (placebo) and was excluded from all analysis. The weekly frequency of anginal attacks was 9 +/- 11 (mean +/- SD) and 9 +/- 10 during the 2 placebo weeks and 11 +/- 14 and 9 +/- 11 during NTG-TTS; the time to 1 mm ST segment depression (seconds) was 268 +/- 178 and 303 +/- 217 with placebo and 228 +/- 221 and 285 +/- 178 with NTG-TTS; exercise duration (seconds) was 375 +/- 230 and 467 +/- 254 during placebo and was 394 +/- 233 and 412 +/- 236 during NTG-TTS. The weekly number of episodes of ST depression was 11 +/- 9 and 8 +/- 5 during placebo and 8 +/- 5 and 9 +/- 7 during NTG-TTS. Our study failed to show any consistent differences in patients treated with placebo or NTG-TTS.

Administration, Topical↗