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John Stewart

Publications and source records attributed to John Stewart.

At least 37 records · Page 2Linked to original sources
PubMed2004

Comparison of hospitalization rates in patients with community-acquired pneumonia treated with telithromycin for 5 or 7 days or clarithromycin for 10 days.

AIMS: To compare the impact on hospitalization rates and the clinical efficacy of oral telithromycin and clarithromycin treatment in patients with community-acquired pneumonia (CAP). METHODS: A total of 581 patients with CAP were enrolled in this randomized, double-blind, parallel group, multinational study, of whom 575 were evaluated for healthcare resource utilization from a payer perspective (intent to treat [ITT] population). Patients received telithromycin 800 mg once daily for 5 (n = 193) or 7 (n = 195)days, or clarithromycin 500 mg once daily for 10 days (n = 187). The primary efficacy endpoint was clinical outcome at test of cure (Days 17-24) in the per-protocol population. Frequency of CAP-related hospitalizations, physician visits/tests/procedures, and additional respiratory tract infection-related antibacterial use were compared by treatment group (ITT) up to late post- for clarithromycin vs dollars 37930 (difference: -26446; therapy (Days 31-36). Study investigators blinded to treatment assessed whether hospital admissions were CAP-related or not. CAP-related hospitalization costs (USdollars) for telithromycin and clarithromycin were compared. RESULTS: Clinical cure rates were similar in patients who received clarithromycin for 10 days and telithromycin for 5 or 7 days: 91.8% (134/146), 89.3% (142/159), and 88.8% (143/161), respectively, and both 5- and 7-day telithromycin were statistically equivalent to clarithromycin (difference: -2.5 and -3.0%, respectively; 95% CI: -9.7, 4.7 and -10.2, 4.3, respectively). There were 7 CAP-related hospital admissions among clarithromycin patients vs 3 (p = 0.283) and 1 (p = 0.021) admissions among 5- and 7-day telithromycin patients, respectively. The number of hospital days/100 patients was 40.1 for clarithromycin vs 17.1 and 7.2 for 5- and 7-day telithromycin, respectively. Projected hospitalization costs/100 patients were dollars 86205 95% CI: -66 654; 13 762) and dollars 16 091 (difference: -37 847; 95% CI: -77953; 2259) for 5- and 7-day telithromycin, respectively. CONCLUSIONS: Data from this study demonstrate that telithromycin 800 mg once daily for 5 or 7 days with fewer hospital days and potentially lower is an effective treatment for CAP,and that telithromycin treatment of CAP may be associated hospitalization costs than clarithromycin treatment.

Administration, Oral↗
PubMed2004

Hospitalization rates among patients with community-acquired pneumonia treated with telithromycin vs clarithromycin: results from two randomized, double-blind, clinical trials.

AIMS: To compare hospitalization rates among patients with community-acquired pneumonia (CAP) treated with oral telithromycin and clarithromycin, based on pooled data from two randomized, double-blind, multinational clinical trials. PATIENTS AND METHODS: Adult patients with CAP eligible for oral therapy (Study 1, n = 448; Study 2, n = 575) received telithromycin 800 mg once daily for 10 (Study 1, 2-arms), 5 or 7 (Study 2, 3-arms) days, or clarithromycin 500 mg twice daily for 10 days. Frequency of CAP-related hospitalizations, physician visits/tests/procedures, and additional respiratory tract infection-related antibacterial use, as well as CAP-related length of hospital stay and hospitalization costs, were compared by treatment group (intent to treat populations) up until the late post-therapy visit (Days 31-36). Study investigators blinded to treatment regimen assessed whether hospital admissions were CAP related. RESULTS: Despite equivalent clinical efficacy for telithromycin vs clarithromycin in the clinically evaluable per-protocol populations (n = 784) (88.8% [428/482] vs 90.1% [272/302]--difference: -1.3%; 95% CI: -6.0, 3.4), telithromycin treatment for 5, 7, or 10 days was associated with significantly fewer CAP-related hospitalizations (p = 0.023) and CAP-related hospital days (p = 0.025) vs clarithromycin (reduction of 2.3 hospitalizations and 23.4 hospital days per 100 patients). Accordingly, estimated CAP-related hospitalization costs were significantly lower (p = 0.025) for telithromycin recipients (30,231 US dollars less per 100 patients). CAP-related hospitalizations, duration of hospital stay, and hospitalization costs for 7- to 10-day telithromycin--the approved dosing regimen for CAP--were significantly lower (p = 0.023, 0.025, and 0.025, respectively) than for clarithromycin. CONCLUSIONS: Data from this study indicate that telithromycin 800 mg once daily for 5, 7, or 10 days provides an effective therapy for patients with CAP, and may be associated with fewer CAP-related hospitalizations and hospital days than clarithromycin 500 mg twice daily for 10 days. Treatment with telithromycin could, therefore, potentially translate into cost savings in the management of CAP.

Adult↗
PubMed2004

Patterns of municipal health expenditure in interwar England and Wales.

This article aims to fill a gap in the history of medical services in England and Wales in the interwar period by focusing on the historiographically neglected municipal sector--a relative neglect that is particularly unjustified given that this sector provided an increasingly wide array of medical services over the period. Focusing on the highly urbanized county boroughs, this article investigates whether and how expenditure on municipal health services changed over the interwar period, and whether these patterns were replicated by boroughs across England and Wales. It is found that many of the largest personal health services were experiencing a common pattern of growing investment over the period, but that county boroughs did not act uniformly in their spending decisions. Considered regionally, the Northeast and the West Midlands were found to perform poorly in expenditure terms compared to the data set as a whole, while the large conurbations of Leeds, Manchester, and Liverpool raised the average performance of the Northwest and Yorkshire. Regional patterns are found to be less consistent in the south of the country, where voluntary provision and demands arising from the boroughs' geographical position (for example, seaside resorts) may have exerted significant influences over levels of expenditure on health.

England↗
PubMed2003

Monocytes heterozygous for the Asp299Gly and Thr399Ile mutations in the Toll-like receptor 4 gene show no deficit in lipopolysaccharide signalling.

Toll-like receptor 4 (TLR4)-mediated recognition of lipopolysaccharide (LPS) is required for efficient recognition of Gram-negative bacterial infections. Two commonly occurring mutations in the human TLR4 gene (Asp299Gly and Thr399Ile) have recently been shown to be associated with blunted physiological responses to inhaled LPS, and with increased risk of Gram-negative bacteraemia in sepsis patients and reduced risk of atherosclerosis in an Italian population. Here we show that monocytes from individuals heterozygous for both mutations in the TLR4 gene exhibit no deficit in recognition of LPS of Escherichia coli, Neisseria meningitidis, Bacteroides fragilis, Yersinia pestis, Chlamydia trachomatis, Porphyromonas gingivalis, or Pseudomonas aeruginosa. We propose that the relatively high frequency of these mutations in the Caucasian population may reflect modified responses of carriers to alternative TLR4 agonists.

Aspartic Acid↗
PubMed2003

Changes in amino-terminal portion of human B2 receptor selectively increase efficacy of synthetic ligand HOE 140 but not of cognate ligand bradykinin.

Recently, we have shown that a widely used antagonist of the human bradykinin B(2) receptor (B(2)R) HOE 140 acts as a full agonist of the chicken ornithokinin receptor (B(o)R). To understand the molecular mechanisms underlying differential efficacy of HOE 140 for the various kinin receptors, we have constructed chimeric kinin receptors (CKR) in which the amino-terminal portion including the first two transmembrane regions and the first extracellular loop (CKR-2) or only the second transmembrane region and the first extracellular loop (CKR-1) of B(2)R were substituted with the corresponding segments of B(o)R. Ligand efficacy of synthetic ligand HOE 140 decreased in the order B(o)R > CKR-2 > CKR-1 > B(2)R, whereas the efficacy of the endogenous kinin ligand was unchanged. Enhanced HOE 140 efficacy was not due to a structural change in the ligand binding site or to an enhanced receptor expression level. Rather, heterologous binding competition studies indicated that structural change(s) introduced into the engineered receptors caused a selective reduction in apparent affinity of HOE 140 for the uncoupled inactive receptor state R but not for the active G protein-coupled state R*, thereby increasing the ratio of R* over R for a given ligand concentration. Our results may help explain the unusually broad efficacy spectrum of HOE 140, which varies from inverse to full agonism, depending on kinin receptor subtype, tissue origin, or species.

Amino Acid Substitution↗
PubMed2002

Trypanosoma cruzi induces edematogenic responses in mice and invades cardiomyocytes and endothelial cells in vitro by activating distinct kinin receptor (B1/B2) subtypes.

Trypanosoma cruzi, the protozoan that causes Chagas' heart disease, invades endothelial cells in vitro by activating the B2 kinin receptor (B2R). Here, we demonstrate that mice infected with trypomastigotes develop potent edema after treatment with the angiotensin-converting enzyme (ACE) (or kininase II) inhibitor captopril. Experiments performed with specific kinin receptor (B2R/B1R) antagonists and knockout mice revealed that the early-phase (3-h) edema is mediated by the constitutive B2R, whereas the late-phase (24-h) response depends on stimulation of the up-regulated B1R. Given previous evidence that parasite invasion of cells expressing B2R is potentiated by captopril, we investigated the prerequisites for in vitro infection of Chinese hamster ovary cells overexpressing either B1R or B2R, human umbilical vein endothelial cells activated by lipopolysaccharide, and neonatal rat cardiomyocytes. Our results indicate that captopril potentiates parasite invasion regardless of the kinin (B2/B1) activation pathways, whereas DL-2-mercaptomethyl-3-guanidino-ethylthiopropanoic acid (MGTA), an inhibitor of kininase I (carboxypeptidase M/N), selectively decreases parasite infectivity for B1R-expressing cells. These data suggest that formation of the B1R agonist, i.e., [des-Arg] kinins, critically depends on the processing action of kininase I, here proposed as a potential pathogenesis cofactor. Collectively, our data suggest that fluctuations in the levels of kininases may modulate parasite infectivity and pathological outcome in Chagas' disease.

Animals↗
PubMed2002

A new statistical method for quantitative analyses: application to the precise quantification of T cell receptor repertoires.

In experimental immunology, a situation quite commonly arises in which there are a large number of potential events but the probability of any individual event is small and one wishes to measure the number of events which actually occur. We present a new general statistical method, denoted Continuous Poisson Method (COPOM), for estimating the number of events underlying a quantitative measurement. This situation is well illustrated in the case of quantitative analyses of the immune receptor repertoire in a diverse population of cells. We show that repetition of T cell receptors (TCRs) complementarity determining region 3 (CDR3) length measurements by Immunoscope, on independent samples containing the similar numbers of cells prepared from splenocytes, results in variable profiles. When analyzed by COPOM, this variability provides direct quantification of the lymphocytes expressing any antigen receptor with a given V, J and CDR3 length inside the cell population. Using COPOM, a single dilution was sufficient to cover events over a 100-fold variation in frequency and the sensitivity of the assay was such that a single cell inside a pool of 5 x 10(4) lymphocytes could be quantified. A comparison of the frequency of splenocytes using either Vbeta14-Jbeta or the specific Vbeta8.3-Jbeta1.1 rearrangement, determined either by our or other approaches, revealed the accuracy and convenience of our method. This approach provides the first precise method able to measure the diversity of the antigen receptor repertoire inside a complex cell population by the use of a single straightforward technique.

Animals↗
PubMed2002

Preparative reversed-phase liquid chromatography of peptides. Isocratic two-step elution system for high loads on analytical columns.

We have developed further our novel sample displacement chromatography (SDC) methodology to carry out preparative separations on analytical equipment and 15-cm analytical columns for sample loads < or = 200 mg. Thus, a two-step isocratic SDC protocol was developed and applied to the purification of important biologically active peptides, i.e. bradykinin antagonists of 10 and 11 residues. Following sample loading in 100% aqueous solvent at a concentration of approximately 7-10 mg/ml (with sample loads varying from 67 to 200 mg) onto a small C18 column (150 x 4.6 mm I.D., made up of three 50-mm columns attached in series), we applied isocratic elution with aqueous acetonitrile at two concentrations, the first (lower concentration) to displace hydrophilic impurities off the column and the second (higher concentration) to displace pure product from the column; hydrophobic impurities remain trapped on the column. This modified SDC approach promises to allow great flexibility in purifying peptides, at high yield of pure product (> 99% purity), and encompassing a range of sample hydrophobicities as well as sample loads (< or = 200 mg) varying by as much as a factor of three.

Chromatography, High Pressure Liquid↗
PubMed2002

Bradykinin antagonist dimer, CU201, inhibits the growth of human lung cancer cell lines by a "biased agonist" mechanism.

All small cell (SCLCs) and many non-small cell lung cancers (NSCLCs) have neuroendocrine features including production of neuropeptides and cell surface receptors creating autocrine and paracrine growth loops. Neuropeptides bind to a family of 7-transmembrane receptors and activate heterotrimeric G proteins consisting of G(alphaq) and G(alpha12,13). Substance P derivatives (SPDs) induced apoptosis and inhibited growth of lung cancer cells by discoordinately inhibiting G(alphaq) and stimulating G(alpha12,13). However, these SPDs had low potency and short half-lives. In this report we show that a bradykinin antagonist dimer, CU201, inhibited the growth of SCLC and NSCLC cell lines with or without multidrug-resistant proteins and was 10-fold more potent with a longer plasma half-life than SPDs. Bradykinin agonists in either monomeric or dimeric form and monomeric bradykinin antagonist have no effect on lung cancer cell growth. The dimeric linking moiety of the two molecules was created, requiring a sufficient number of carbon chains to provide critical spacing between the two antagonists. CU201 inhibited intracellular Ca2+ release in response to bradykinin, indicating blockage of the G(alphaq) signal, and stimulated c-Jun kinases, indicating stimulation of the G(alpha12,13) pathway. CU201-induced apoptosis was preceded by unique changes in apparent nuclear DNA binding and by c-Jun kinase and caspase-3 activation. At the concentration at which CU201 inhibited the growth of the cancer cells, it had no effect on the growth of normal lung cells in vitro. CU201 and similar compounds offer hope of becoming a new form of targeted therapy for tumors with neuroendocrine properties.

Antineoplastic Agents↗
PubMed2002

Pediatric meralgia paresthetica.

Meralgia paresthetica is a focal peripheral neuropathy involving the lateral femoral cutaneous nerve and is rarely observed in pediatric practice. Previous reports have highlighted its occurrence within the context of a regional bony malignancy. We present here three patients less than 18 years of age with idiopathic meralgia paresthetica.

Adolescent↗
PubMed2002

Genetics, biology and multifactorial diseases.

The schematic concept of "levels of causal interaction" is applied to the relation between genetics and biology. The strength of classical formal genetics lies in its power to proceed directly from observations on an external phenotype, to inferences concerning the nature and properties of the fundamental genetic factors. Its weakness comes from the fact that by short-circuiting the causal chain leading from genotype to phenotype, it creates a divorce between genetics and biology. It is argued that in order to reestablish an articulation of genetics and the biology of whole organisms, it will be necessary to study in detail the entire causal chain leading from a difference in a genetic factor to a difference in a corresponding phenotypic character. This proposal is illustrated by a consideration of multifactorial diseases, which appear to be due to strong interactions between a moderate number of distinct loci; the frequency of "abnormal" alleles at any given locus may be surprisingly high.

Alleles↗
PubMed2002

A state-wide assessment of the obstetric, anesthesia, and operative team personnel who are available to manage the labors and deliveries and to treat the complications of women who attempt vaginal birth after cesarean delivery.

OBJECTIVE: The purpose of this study was to determine on a state-wide basis the range of obstetric, anesthesia, and surgical team personnel who were available immediately to manage the labors and deliveries of women who attempted vaginal birth after cesarean delivery. Additionally, we tried to determine whether hospitals had stopped performing vaginal births after cesarean delivery or made changes in their policies regarding vaginal birth after cesarean delivery as a result of recent American College of Obstetricians and Gynecologists recommendations. STUDY DESIGN: Available immediately was defined as "being present in the hospital." All hospitals that provided obstetric care in the State of Ohio were surveyed to determine whether an obstetrician with cesarean privileges, an anesthesiologist, or an anesthetist capable of independently administering anesthesia for a cesarean section, and a surgical team were available immediately when women attempted vaginal birth after cesarean delivery. The hospitals were also asked whether they had stopped allowing vaginal births after cesarean delivery or had made changes in their vaginal birth after cesarean delivery policies in response to the recent recommendations of the American College of Obstetricians and Gynecologists. Data were computerized and analyzed by the chi(2) test. RESULTS: Seventy-seven (93.9%), 35 (100%), and 13 (100%) of level I, II, and III hospitals performed vaginal births after cesarean delivery. An obstetrician was immediately available in 27.3%, 62.9%, and 100% of level I, II, and III institutions, respectively (P <or=.001). Anesthesia availability was 39%, 100%, and 100% of level I, II, and III institutions, respectively (P <or=.001). A surgical team was available in 35.1%, 97.1%, and 100% of level I, II, and III hospitals, respectively (P <or=.001). A complete complement was available in 15.6%, 62.9%, and 100% of level I, II and III institutions, respectively (P <or=.001). Two hospitals had stopped the performance of vaginal births after cesarean delivery, and 10 additional hospitals were considering stopping the performance of vaginal births after cesarean delivery. Policy changes had been adopted in 15 institutions, and 4 other institutions were considering changes. CONCLUSION: Most level I and many level II hospitals provide less than optimum staffing when women are attempting vaginal birth after cesarean delivery. Because vaginal births after cesarean delivery are equally distributed among level I, II, and III institutions in this state, many women may be attempting vaginal birth after cesarean delivery under less than optimal conditions. The data suggest the need for changes in staffing or referral patterns to safely meet the Healthy People 2010 goal of increasing the vaginal birth after cesarean delivery rate nationally.

Anesthesia, Obstetrical↗
PubMed2002

Towards the genetic analysis of mulfactorial diseases: the estimation of allele frequency and epistasis.

OBJECTIVES: The general aim of this paper is to reactivate the original intention behind the Elston-Stewart algorithm: i.e. physiological characterisation of the effects of individual loci underlying quantitative variation. The specific aim is the estimation of allele frequency and epistasis in multifactorial genetic diseases. METHODS: In a general genetic model, the probability of disease is a sigmoid function of the number of disease alleles summed over all loci. This model has just 4 parameters: the number of loci; the population frequency of disease alleles; a threshold expressed as a proportion of disease alleles; and the slope of the sigmoid curve. Assuming 10 loci, the remaining parameters can be estimated from empirical data: population frequency of the disease, monozygotic twin concordance rates, and disease frequency in sibs of affected probands. RESULTS: For 10 typical multifactorial diseases, the estimates of allele frequency are generally high, of the order of 20%, with strong epistatic interactions between loci. It follows that the frequencies of subphenotypes specific for a single disease locus will also be high, and only about two-fold greater in affected individuals than in normal controls. CONCLUSIONS: Because of allelic heterogeneity, purely genomic approaches are unlikely to succeed in unravelling the genetics of multifactorial diseases; this will rather require articulation with physiology and the identification of biologically meaningful subphenotypes.

Diabetes Mellitus, Type 1↗
PubMed2002

A genome-wide scan for linkage to chromosomal regions in 382 sibling pairs with schizophrenia or schizoaffective disorder.

OBJECTIVE: Some genome-wide scans and association studies for schizophrenia susceptibility genes have yielded significant positive findings, but there is disagreement between studies on their locations, and no mutation has yet been found in any gene. Since schizophrenia is a complex disorder, a study with sufficient power to detect a locus with a small or moderate gene effect is necessary. METHOD: In a genome-wide scan of 382 sibling pairs with a diagnosis of schizophrenia or schizoaffective disorder, 396 highly polymorphic markers spaced approximately 10 centimorgans apart throughout the genome were genotyped in all individuals. Multipoint nonparametric linkage analysis was performed to evaluate regions of the genome demonstrating increased allele sharing, as measured by a lod score. RESULTS: Two regions with multipoint maximum lod scores suggesting linkage were found. The highest lod scores occurred on chromosome 10p15-p13 (peak lod score of 3.60 at marker D10S189) and the centromeric region of chromosome 2 (peak lod score of 2.99 at marker D2S139). In addition, a maximum lod score of 2.00 was observed with marker D22S283 on chromosome 22q12, which showed evidence of an imprinting effect, whereby an excess sharing of maternal, but not paternal, alleles was present. No evidence of linkage was obtained at several locations identified in previous studies, including chromosomes 1q, 4p, 5p-q, 6p, 8p, 13q, 15p, and 18p. CONCLUSIONS: The findings of this large genome-wide scan emphasize the weakness and fragility of linkage reports on schizophrenia. No linkage appears to be consistently replicable across large studies. Thus, it has to be questioned whether the genetic contribution to this disorder is detectable by these strategies and the possibility raised that it may be epigenetic, i.e., related to gene expression rather than sequence variation. Nevertheless, the positive findings on chromosome 2, 10, and 22 should be pursued further.

Chromosome Mapping↗
PubMed2002

The biological activity of a liposomal complete core lipopolysaccharide vaccine.

A vaccine that induces humoral immunity to lipopolysaccharide (LPS), while remaining non-pyrogenic should be beneficial, as high levels of antibodies against LPS are associated with a reduced risk of adverse outcome. However, pure LPS or bacteria expressing LPS are generally considered too toxic to be used as vaccines. Recently, a novel, immunogenic complete core lipopolysaccharide vaccine has been described, which has been designed to prevent endotoxin-related inflammatory reactions in surgical and high-risk hospitalized patients. In vivo studies have shown that while administration of the vaccine to rabbits results in no toxicity over 7 days, it does induce significantly enhanced antibody responses towards a broad range of clinically relevant Gram-negative LPSs. Here we show that encapsulation of the four complete core LPS types Escherichia coli K12, Escherichia coli R1, Bacteroides fragilis and Pseudomonas aeruginosa into liposomes greatly reduces the ability of a given amount of LPS to induce TNF-alpha production in vitro from human monocytes. In contrast to previous studies of liposomal LPS, we demonstrate a reduction in activity of approximately 100,000-fold; a reduction approximately 100-1,000-fold more than that previously described. The signalling by the liposomal LPS appears to be entirely dependent on serum factors, though this can be partially restored by soluble CD14 or, to a lesser extent, by lipopolysaccharide binding protein. Time-course experiments reveal that liposomal LPS signalling shows similar kinetics to pure LPS signalling. Therefore, as well as inducing specific antibody responses, liposomal LPS demonstrates characteristics suitable for use as a vaccine to be used in human beings.

Animals↗