Typhoid fever vaccines.
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Bacterial Vaccines↗
Biomedical subjects
J Lau
Publications and source records attributed to J Lau.
Pharmacotherapy for hypertension in the elderly.
OBJECTIVES: To quantify the long-term effects of antihypertensive drug therapy on morbidity and mortality in the elderly. To characterize co morbid risk profiles of trial participants. SEARCH STRATEGY: Electronic search of WHO-ISH Collaboration register (August 1997), The Cochrane Library (1997; Issue 1), MEDLINE (1966 to April 1997) and two Japanese databases (1973-1995); references from reviews, trials and 10 previously published meta-analyses; and experts. SELECTION CRITERIA: Randomized controlled trials of at least one year duration in hypertensive elders (at least 60 years old) assessing antihypertensive drug therapy and providing morbidity and mortality data. DATA COLLECTION AND ANALYSIS: At least two independent reviewers abstracted data on morbidity and mortality results and trial characteristics. The following outcomes were assessed: total mortality; coronary heart disease (CHD) mortality; combined CHD morbidity and mortality; cerebrovascular mortality; combined cerebrovascular morbidity and mortality; cardiovascular mortality; combined cardiovascular morbidity and mortality; and drop outs due to side effects of treatment. MAIN RESULTS: Fifteen trials including 21,908 elderly subjects were identified. The average prevalence of cardiovascular risk factors, cardiovascular disease, and competing co morbid diseases was lower among trial participants than the general population of hypertensive elderly persons. Most subjects were 60 to 80 years old. Most trials were conducted in Western, industrialized countries and evaluated diuretic and beta-blocker therapies. Event rates per 1000 participants over approximately 5 years indicated that antihypertensive drug therapy was beneficial. Cardiovascular morbidity and mortality was reduced from 177 to 126 events (95% CI of the difference 31 to 73). Cardiovascular mortality was reduced from 69 to 50 deaths (95% CI of the difference 9 to 31). Total mortality was reduced from 129 to 111 deaths (95% CI of difference 4 to 28). The data from the three trials restricted to persons with isolated systolic hypertension indicated a significant benefit: cardiovascular morbidity and mortality over approximately 5 years was reduced from 157 to 104 events per 1000 participants (95% CI of the difference 12 to 89). Numbers of participants who dropped out of trials secondary to adverse drug effects were often not reported. The four trials that did report this data showed a wide variation in drop out rates ranging from no significant differences between treatment and control groups to as many as one out of four patients dropping out due to side effects of treatment. REVIEWER'S CONCLUSIONS: Randomized controlled trials establish that treating healthy older persons with hypertension is highly efficacious. Benefits of treatment with low dose diuretics or beta-blockers are clear for persons in their 60s to 70s with either diastolic or systolic hypertension. Differential treatment effects based on patient risk factors, pre-existing cardiovascular disease and competing co-morbidities could not be established from the published trial data.
Aged↗
Beta-sitosterols for benign prostatic hyperplasia.
OBJECTIVES: This systematic review aimed to assess the effects of beta-sitosterols (B-sitosterol) on urinary symptoms and flow measures in men with of benign prostatic hyperplasia (BPH). SEARCH STRATEGY: Trials were searched in computerized general and specialized databases (MEDLINE, EMBASE, Cochrane Library, Phytodok), by checking bibliographies, and by contacting manufacturers and researchers. SELECTION CRITERIA: Trials were eligible for inclusion provided they (1) randomized men with BPH to receive B-sitosterol preparations in comparison to placebo or other BPH medications, and (2) included clinical outcomes such as urologic symptom scales, symptoms, or urodynamic measurements. DATA COLLECTION AND ANALYSIS: Information on patients, interventions, and outcomes was extracted by at least two independent reviewers using a standard form. Main outcome measure for comparing the effectiveness of B-sitosterols with placebo and standard BPH medications was the change in urologic symptom scale scores. Secondary outcomes included changes in nocturia as well as urodynamic measures (peak and mean urine flow, residual volume, prostate size). Main outcome measure for side effects was the number of men reporting side effects. MAIN RESULTS: 519 men from 4 randomized, placebo-controlled, double-blind trials, (lasting 4 to 26 weeks) were assessed. 3 trials used non-glucosidic B-sitosterols and one utilized a preparation that contained 100% B-sitosteryl-B-D-glucoside. B-Sitosterols improved urinary symptom scores and flow measures. The weighted mean difference (WMD) for the IPSS was -4.9 IPSS points (95%CI = -6.3 to -3.5, n = 2 studies). The WMD for peak urine flow was 3.91 ml/sec (95%CI = 0.91 to 6.90, n = 4 studies) and the WMD for residual volume was -28.62 ml (95%CI = -41. 42 to -15.83, n = 4 studies). The trial using 100% B-sitosteryl-B-D-glucoside (WA184) show improvement in urinary flow measures. B-sitosterols did not reduce prostate size. Withdrawal rates for men assigned to B-sitosterol and placebo were 7.8% and 8. 0%, respectively. REVIEWER'S CONCLUSIONS: The evidence suggests non-glucosidic B-sitosterols improve urinary symptoms and flow measures. Their long term effectiveness, safety and ability to prevent BPH complications are not known.
Humans↗
Vaccines for preventing typhoid fever.
BACKGROUND: Whole cell vaccines, consisting of relatively crude preparations of Salmonella typhi administered parenterally, are effective but have a high incidence of adverse effects. Two vaccines have been developed more recently. Ty21a (an attenuated strain of S. typhi administered orally) and Vi (the purified bacterial capsule, given parenterally), have appeared less toxic than the older whole cell vaccines and are thought to be equally effective. OBJECTIVES: The objective of this review was to assess the effects of typhoid fever vaccines. SEARCH STRATEGY: We searched the Cochrane Library, Medline, Index Medicus, Embase and reference lists of articles. SELECTION CRITERIA: Randomised trials comparing typhoid vaccines to other types of vaccine or placebo. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality and extracted data. MAIN RESULTS: Seventeen studies, involving nearly two million people, were included. For the whole cell vaccines single dose regimens provided significant protection for the first two years. Two dose regimens provided significant protection for five years. For the Ty21a vaccine, both two and three dose regimens provided statistically significant protection for two years. The three dose regimen provided protection in the third and fourth years, but protection was not statistically significant in the fifth year. The Vi vaccine provided protection for two years, but the protection in the third year was not significant. The three year cumulative efficacy of two doses of whole cell vaccines was 73% (95% confidence interval 65-80), three doses of Ty21a was 51%, (95% confidence interval 35 to 63) and one dose of Vi was 55% (95% confidence interval 30 to 71). Data on adverse effects were limited, but indicate that whole cell vaccines are more toxic than the newer Ty21a and Vi vaccines. REVIEWER'S CONCLUSIONS: The whole cell vaccines provided more prolonged protection than either the Ty21a vaccine or the Vi vaccine. However whole cell vaccines are associated with higher toxicity.
Adolescent↗
Serenoa repens for benign prostatic hyperplasia.
OBJECTIVES: This systematic review aimed to assess the effects of Serenoa repens in the treatment of Benign Prostatic Hyperplasia (BPH). SEARCH STRATEGY: Trials were searched in computerized general and specialized databases (MEDLINE, EMBASE, Cochrane Library, Phytodok), by checking bibliographies, and by contacting manufacturers and researchers. SELECTION CRITERIA: Trials were eligible if they (1) randomized men with BPH to receive preparations of Serenoa repens (alone or in combination) in comparison with placebo or other BPH medications, and (2) included clinical outcomes such as urologic symptom scales, symptoms, or urodynamic measurements. Eligibility was assessed by at least two independent observers. DATA COLLECTION AND ANALYSIS: Information on patients, interventions, and outcomes was extracted by at least two independent reviewers using a standard form. The main outcome measure for comparing the effectiveness of Serenoa repens with placebo or other BPH medications was the change in urologic symptom scale scores. Secondary outcomes included changes in nocturia and urodynamic measures. The main outcome measure for side effects was the number of men reporting side effects. MAIN RESULTS: 2939 men from18 randomized trials lasting 4 to 48 weeks were assessed. 16 trials were double-blinded and treatment allocation concealment was adequate in 9 studies. Compared with placebo, Serenoa repens improved urinary symptom scores, symptoms, and urinary flow measures. The weighted mean difference (WMD) for the urinary symptom score was -1.41 points (scale range 0-19), (95%CI = -2.52, -0.30, n = 1 study) and the risk ratio (RR) for self rated improvement was 1.75 (95%CI = 1.21, 2.54, n = 6 studies). The WMD for nocturia was -0.76 times per evening (95%CI = -1.22, -0.32; n = 10 studies). The WMD for peak urine flow was 1.93 ml/sec (95%CI = 0.72, 3.14, n = 8 studies). Compared with finasteride, Serenoa repens produced similar improvements in urinary symptom scores (WMD = 0.37 IPSS points (scale range 0-35), 95%CI = -0.45, 1.19, n = 2 studies) and peak urine flow (WMD = -0.74 ml/sec, 95%CI = -1.66, 0.18, n = 2 studies). Adverse effects due to Serenoa repens were mild and infrequent. Withdrawal rates in men assigned to placebo, Serenoa repens or finasteride were 7%, 9%, and 11%, respectively. REVIEWER'S CONCLUSIONS: The evidence suggests that Serenoa repens improves urologic symptoms and flow measures compared with placebo. Serenoa repens produced similar improvement in urinary symptoms and flow compared to finasteride and is associated with fewer adverse treatment events. The long term effectiveness, safety and ability to prevent BPH complications are not known.
Androgen Antagonists↗
Short-term treatment with proton pump inhibitors, H2-receptor antagonists and prokinetics for gastro-oesophageal reflux disease-like symptoms and endoscopy negative reflux disease.
BACKGROUND: Heartburn affects 25% of the adult population on a monthly basis and represents the core symptom of gastro-oesophageal reflux disease (GORD). Treatment is readily available and puts a large demand on healthcare budgets. Research in the past has focused largely on the treatment of oesophagitis. A majority of GORD patients show no endoscopic abnormalities and in daily practice most patients are treated empirically. OBJECTIVES: Summarise, quantify and compare the efficacy of the short-term use of proton pump inhibitors (PPI), H2-receptor antagonists (H2RA) and prokinetics in the empirical treatment of GORD and the treatment of endoscopy negative reflux disease (ENRD). SEARCH STRATEGY: Electronic searches were performed of the Cochrane Controlled Trials Register, MEDLINE and EMBASE. Bibliographies were screened. SELECTION CRITERIA: Included were randomised controlled trials focussing on symptomatic outcome after short-term treatment for GORD using proton pump inhibitors, H2-receptor antagonists or prokinetic agents. Participants had to be classifiable in the empirical treatment group (no endoscopy used in treatment allocation) or in the endoscopy negative reflux disease group (no endoscopic signs of erosive oesophagitis). DATA COLLECTION AND ANALYSIS: Data from included trials were extracted by two reviewers independently. The impact of interventions was expressed as relative risks (RR) together with 95% confidence intervals (95% CI). Meta-analysis was only performed if there were sufficient trials of similar comparisons reporting the same outcomes. Relative risks were combined for binary outcomes. MAIN RESULTS: Twenty-one trials were included: eleven in the empirical treatment group, seven in the ENRD group and three in both. In empirical treatment of GORD the RR for heartburn remission in placebo-controlled trials for PPI was 0.35 (1 trial, 95% CI 0.26 to 0.46), for H2RAs 0.77 (2 trials, 95% CI 0.60 to 0.99) and for prokinetics 0.86 (1 trial, 95% CI 0.73 to 1.01). In direct comparison PPIs were significantly (p<0.05) more effective than H2RAs (3 trials, RR 0.67, 95% CI 0.57 to 0.80) and prokinetic's (2 trials, RR 0.53, 95% CI 0.32 to 0.87). In treatment of ENRD, RR for heartburn remission for PPI versus placebo was 0.68 (4 trials, 95% CI 0.53 to 0.88) and for H2RA versus placebo was 0.84 (2 trials, 95% CI 0.74 to 0.95). The RR for PPI versus H2RA was 0.69 (2 trials, 95% CI 0.39 to 1.20) and versus prokinetic 0.72 (1 trial, 95% CI 0.56 to 0.92). REVIEWER'S CONCLUSIONS: The findings in this review suggest that antisecretory drugs are effective in the empirical treatment of complaints likely to originate from GORD and in treatment of ENRD and furthermore that PPIs are superior to H2RAs in empirical treatment of typical GORD symptoms.
Endoscopy, Digestive System↗
Diagnosis and treatment of uncomplicated acute bacterial rhinosinusitis: summary of the Agency for Health Care Policy and Research evidence-based report.
PURPOSE: The goal was to critically examine evidence regarding the performance of diagnostic tests and the efficacy of antibiotic and other treatments for uncomplicated acute bacterial rhinosinusitis (ABR). METHODS: Scientific literature was reviewed, and meta-analysis methods were used to assess diagnostic test and antibiotic efficacy. A decision analysis and cost-effective analysis were performed. RESULTS: Although more sensitive than clinical examination for diagnosis of ABR, sinus radiograms are not cost-effective as an initial management strategy. Antibiotics reduce the incidence of clinical failures by one half compared to no treatment and, when coupled with clinical criteria-based diagnosis, present the most cost-effective treatment strategy. However, without antibiotics, symptoms in two thirds of patients improve by 14 days with no serious complications. The risk of treatment failure does not differ significantly between amoxicillin or folate inhibitors and newer, more expensive antibiotics. CONCLUSIONS: The current literature shows that treatment of uncomplicated ABR with amoxicillin or folate inhibitors and based on clinical criteria is the most cost-effective strategy.
Acute Disease↗
New highly potent dipeptidic growth hormone secretagogues with low molecular weight.
Based on NN703, low molecular weight growth hormone secretagouges (GHSs) with a reduced number of hydrogen binding sites were designed by removal of the C-terminal amide group. The compounds were highly potent in combination with high efficacy in a rat pituitary cell assay, being characterized with EC(50) values down to 0.8 nM. Selected compounds were tested in in vivo animal models. The oral bioavailability in dogs was 16-44%. Also, the ED(50) values of the compounds were determined both in dog and swine.
Administration, Oral↗
Meta-analysis in hematology and oncology.
In 1992, a review article about meta-analysis identified only 15 meta-analyses of randomized, controlled trials of cancer therapy. Since then, the total number of meta-analyses in this field has increased almost sixfold. More importantly, the number of randomized, controlled trials in this discipline has also grown tremendously. The expansion in the literature will provide a fertile ground for future meta-analyses. The quality of the recent publications has also improved. An ongoing world-wide effort, the Cochrane Collaboration, is systematically assembling and synthesizing several hundred thousand randomized, controlled trials to improve the delivery of health care. Meta-analysis has many important advantages. It allows the viewing of the complete picture of the evidence. The advent of meta-analysis has sensitized researchers to issues of quality and has improved methodology in clinical research. Detection and explanation of bias and heterogeneity are prime objectives of meta-analysis in clinical research. An array of methods has been developed that allows a better understanding of bias and heterogeneity, beyond simple averaging of results from diverse studies. Meta-analyses of individual patient data, in particular, may promote the development of international collaborations. Several examples of their application are already available in oncology. Meta-analysis may point out deficiencies in the study design of past and current studies, suggest the need for new studies, and inform researchers about the size and design of these studies. In the end, meta-analysis helps to integrate evidence and make recommendations for medical care and medical practice.
Clinical Trials as Topic↗
Meta-analysis of diagnostic tests for acute sinusitis.
To facilitate management of acute sinusitis, we conducted a meta-analysis of published studies comparing diagnostic tests for this disorder. Thirteen studies were identified through literature search. Based on sinus puncture/aspiration (considered most accurate), 49-83% of symptomatic patients had acute sinusitis. Compared with puncture/aspiration, radiography offered moderate ability to diagnose sinusitis (summary receiver operator curve [SROC] area, 0.83). Using sinus opacity or fluid as the criterion for sinusitis, radiography had sensitivity of 0.73 and specificity of 0.80. Studies evaluating ultrasonography revealed substantial variation in test performance. The clinical evaluation, particularly risk scores formally incorporating history and physical examination findings, had moderate ability to identify patients with positive radiographs (SROC area, 0.74). Many studies were of poor quality, with inadequately described test methods and unblinded test interpretation. In conclusion, acute sinusitis is common among symptomatic patients. Radiography and clinical evaluation (especially risk scores) appear to provide useful information for diagnosis of sinusitis.
Acute Disease↗
An estimate of long-term care needs and identification of risk factors for institutionalization among Hong Kong Chinese aged 70 years and over.
BACKGROUND: The goal of this study is to estimate the long-term care needs of the Hong Kong Chinese population age 70 years and older, and to identify risk factors for institutionalization. METHODS: A three-year prospective follow-up study was carried out in Hong Kong Special Administrative Region, China. 2,032 subjects aged 70 years and older were recruited territory-wide by stratified random sampling of the Old Age and Disability Allowance register, covering over 90% of the elderly population. A questionnaire was administered at baseline to obtain information on social, functional, physical, and mental health status, and place of residence. A repeat interview was carried out at 36 months. The number of subjects moving from home to institution or vice versa, and the number who had died, were noted. Univariate analysis was performed to determine risk factors for institutionalization, and backward stepwise multiple logistic regression was used to identify independent factors predisposing to institutionalization. RESULTS: The institutionalization rate per year is estimated to be 0.7% for the 70-79 age group, and 1.5% for the 80+ age group. Using population figures projected by the Hong Kong Census, the corresponding number of places required will be 24,150 and 42,000, respectively, for the two age groups by 2005, whereas the number of government subvented places projected to be available is unlikely to be more than 40,000 for the whole population. Age, being a woman, being single, not having a formal education, cognitive impairment, physical dependency, and the presence of depressive symptoms were factors predisposing to institutionalization. In multivariate analysis, age, marital status, and dependency were identified as independent factors. CONCLUSION: The requirement for institutional places is unlikely to be met by government, the shortfall likely to be met by the private sector. Maintenance of functional independence, good social support network, engagement in social activities, and good informal carer support may reduce demand for institutional care.
Activities of Daily Living↗
Evaluation of technologies for identifying acute cardiac ischemia in emergency departments.
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Acute Disease↗
Diagnosis and treatment of uncomplicated acute sinusitis in children.
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Acute Disease↗
Synthesis of novel GABA uptake inhibitors. 4. Bioisosteric transformation and successive optimization of known GABA uptake inhibitors leading to a series of potent anticonvulsant drug candidates.
By bioisosteric transformations and successive optimization of known GABA uptake inhibitors, several series of novel GABA uptake inhibitors have been prepared by different synthetic approaches. These compounds are derivatives of nipecotic acid and guvacine, substituted at the nitrogen of these amino acids by various lipophilic moieties such as diarylaminoalkoxyalkyl or diarylalkoxyalkyl. The in vitro values for inhibition of [(3)H]GABA uptake in rat synaptosomes was determined for each compound, and it was found that the most potent compound from this series, (R)-1-(2-(3,3-diphenyl-1-propyloxy)ethyl)-3-piperidinecarboxyli c acid hydrochloride (29), is so far the most potent parent compound inhibiting GABA uptake into synaptosomes. Structure-activity results confirm our earlier observations, that an electronegative center in the chain connecting the amino acid and diaryl moiety is very critical in order to obtain high in vitro potency. Several of the novel compounds were also evaluated for their ability in vivo to inhibit clonic seizures induced by a 15 mg/kg (ip) dose of methyl 6, 7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM). Some of the compounds tested show a high in vivo potency comparable with that of the recently launched anticonvulsant product 6 ((R)-1-(4, 4-bis(3-methyl-2-thienyl)-3-butenyl)-3-piperidinecarboxylic acid).
Animals↗
N-substituted adenosines as novel neuroprotective A(1) agonists with diminished hypotensive effects.
The synthesis and pharmacological profile of a series of neuroprotective adenosine agonists are described. Novel A(1) agonists with potent central nervous system effects and diminished influence on the cardiovascular system are reported and compared to selected reference adenosine agonists. The novel compounds featured are derived structurally from two key lead structures: 2-chloro-N-(1-phenoxy-2-propyl)adenosine (NNC 21-0041, 9) and 2-chloro-N-(1-piperidinyl)adenosine (NNC 90-1515, 4). The agonists are characterized in terms of their in vitro profiles, both binding and functional, and in vivo activity in relevant animal models. Neuroprotective properties assessed after postischemic dosing in a Mongolian gerbil severe temporary forebrain ischemia paradigm, using hippocampal CA1 damage endpoints, and the efficacy of these agonists in an A(1) functional assay show similarities to some reference adenosine agonists. However, the new compounds we describe exhibit diminished cardiovascular effects in both anesthetized and awake rats when compared to reference A(1) agonists such as (R)-phenylisopropyladenosine (R-PIA, 5), N-cyclopentyladenosine (CPA, 2), 4, N-[(1S,trans)-2-hydroxycyclopentyl]adenosine (GR 79236, 26), N-cyclohexyl-2'-O-methyladenosine (SDZ WAG 994, 27), and N-[(2-methylphenyl)methyl]adenosine (Metrifudil, 28). In mouse permanent middle cerebral artery occlusion focal ischemia, 2-chloro-N-[(R)-[(2-benzothiazolyl)thio]-2-propyl]adenosine (NNC 21-0136, 12) exhibited significant neuroprotection at the remarkably low total intraperitoneal dose of 0.1 mg/kg, a dose at which no cardiovascular effects are observed in conscious rats. The novel agonists described inhibit 6, 7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate-induced seizures, and in mouse locomotor activity higher doses are required to reach ED(50) values than for reference A(1) agonists. We conclude that two of the novel adenosine derivatives revealed herein, 12 and 5'-deoxy-5'-chloro-N-[4-(phenylthio)-1-piperidinyl]adenosine (NNC 21-0147, 13), representatives of a new series of P(1) ligands, reinforce the fact that novel selective adenosine A(1) agonists have potential in the treatment of cerebral ischemia in humans.
Adenosine↗
Synthesis of novel GABA uptake inhibitors. 3. Diaryloxime and diarylvinyl ether derivatives of nipecotic acid and guvacine as anticonvulsant agents.
(3R)-1-[4,4-bis(3-methyl-2-thienyl)-3-butenyl]-3-piperidinecarboxylic acid 1 (tiagabine, Gabitril) is a potent and selective gamma-aminobutyric acid (GABA) uptake inhibitor with proven anticonvulsant efficacy in humans. This drug, which has a unique mechanism of action among marketed anticonvulsant agents, has been launched for add-on treatment of partial seizures with or without secondary generalization in patients >12 years of age. Using this new agent as a benchmark, we have designed two series of novel GABA uptake inhibitors of remarkable potency, using a putative new model of ligand interaction at the GABA transporter type 1 (GAT-1) uptake site. This model involves the postulated interaction of an electronegative region in the GABA uptake inhibitor with a positively charged domain in the protein structure of the GAT-1 site. These two novel series of anticonvulsant agents contain diaryloxime or diarylvinyl ether functionalities linked to cyclic amino acid moieties and were derived utilizing the new model, via a series of design steps from the known 4,4-diarylbutenyl GABA uptake inhibitors. The new compounds are potent inhibitors of [(3)H]-GABA uptake in rat brain synaptosomes in vitro, and their antiepileptic potential was demonstrated in vivo by their ability to protect against seizures induced by the benzodiazepine receptor inverse agonist methyl 4-ethyl-6,7-dimethoxy-beta-carboline-3-carboxylate (DMCM) in mice. From structure-activity studies of these new GABA uptake inhibitors, we have shown that insertion of an ether oxygen in conjugation with the double bond in tiagabine (K(i) = 67 nM) improves in vitro potency by 5-fold to 14 nM.
Animals↗
Adjuvant intra-arterial iodine-131-labelled lipiodol for resectable hepatocellular carcinoma: a prospective randomised trial.
BACKGROUND: Resection of hepatocellular carcinoma is potentially curative, but local recurrence is common. In this prospective randomised trial, we aimed to find out if one dose of postoperative adjuvant intra-arterial iodine-131-labelled lipiodol could reduce the rate of local recurrence and increase disease-free and overall survival. METHODS: Patients who underwent curative resection for hepatocellular carcinoma and recovered within 6 weeks were randomly assigned one 1850 MBq dose of 131I-lipiodol or no further treatment (controls). We compared rates of recurrence and disease-free and overall survival (the primary endpoints) between the two groups by intention to treat. We planned an interim analysis when 30 patients (both groups together) had been followed up for a median of 2 years, with the intention of stopping early if the between-group difference in disease-free survival was significant (p=0.029). FINDINGS: Between April, 1992, and August, 1997, we recruited 43 patients: 21 received intra-arterial 131I-lipiodol and 22 received no adjuvant treatment. During a median follow-up of 34.6 (range 14.1-69.7) months, there were six (28.5%) recurrences among the 21 patients in the adjuvant treatment, compared with 13 (59%) in the controls (p=0.04). Median disease-free survival in the treatment and control groups was 57.2 (0.4-69.7) and 13.6 (2.1-68.3) months, respectively (p=0.037). 3-year overall survival in the treatment and control groups was 86.4% and 46.3%, respectively (p=0.039). The interim analysis showed a significant increase in disease-free survival in the treatment group compared with the controls (p=0.01), so we closed the trial early. 131I-lipiodol had no significant toxic effects. INTERPRETATION: In patients with hepatocellular carcinoma, one 1850 MBq dose of intra-arterial 131I-lipiodol given after curative resection significantly decreases the rate of recurrence and increases disease-free and overall survival.
Adolescent↗
Dissecting the role of acyltransferase domains of modular polyketide synthases in the choice and stereochemical fate of extender units.
Modular polyketide synthases (PKSs), such as the 6-deoxyerythronolide B synthase (DEBS), are large multifunctional enzyme complexes that are organized into modules, where each module carries the domains needed to catalyze the condensation of an extender unit onto a growing polyketide chain. Each module also dictates the stereochemistry of the chiral centers introduced into the backbone during the chain elongation process. Here we used domain mutagenesis to investigate the role of the acyl transferase (AT) domains of individual modules in the choice and stereochemical fate of extender units. Our results indicate that the AT domains of DEBS do not influence epimerization of the (2S)-methylmalonyl-CoA extender units. Hence, stereochemical control of the methyl-branched centers generated by DEBS most likely resides in the ketosynthase (KS) domains of the individual modules. In contrast, several recent studies have demonstrated that extender unit specificity can be altered by AT domain substitution. In some of these examples, the resulting polyketide was produced at considerably lower titers than the corresponding natural product. We analyzed one such attenuated mutant of DEBS, in which the methylmalonyl transferase domain of module 2 was replaced with a malonyl transferase domain. As reported earlier, the resulting PKS produced only small quantities of the expected desmethyl analogue of 6-deoxyerythronolide B. However, when the same hybrid module was placed as the terminal module in a truncated 2-module PKS, it produced nearly normal quantities of the expected desmethyl triketide lactone. These results illustrate the limits to modularity of these multifunctional enzymes. To dissect the role of specific amino acids in controlling AT substrate specificity, we exchanged several segments of amino acids between selected malonyl and methylmalonyl transferases, and found that a short (23-35 amino acid) C-terminal segment present in all AT domains is the principal determinant of their substrate specificity. Interestingly, its length and amino acid sequence vary considerably among the known AT domains. We therefore suggest that the choice of extender units by the PKS modules is influenced by a "hypervariable region", which could be manipulated via combinatorial mutagenesis to generate novel AT domains possessing relaxed or altered substrate specificity.
Acyl Coenzyme A↗