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Biomedical subjects

C Webster

Publications and source records attributed to C Webster.

At least 37 records · Page 2Linked to original sources
PubMed1998

Rates of tuberculosis infection in healthcare workers providing services to HIV-infected populations. Terry Beirn Community Programs for Clinical Research on AIDS.

OBJECTIVE: To assess the prevalence of tuberculosis (TB) or a positive skin test in healthcare workers (HCWs) providing services to human immunodeficiency virus (HIV)-infected individuals and to determine prospectively the incidence of new infections in this population. DESIGN: This prospective cohort study enrolled 1,014 HCWs working with HIV-infected populations from 10 metropolitan areas. Purified protein derivative (PPD) tuberculin skin tests were placed at baseline and every 6 months afterwards on those without a history of TB or a positive PPD. Demographic, occupational, and TB exposure data also were collected. SETTING: Outpatient clinics, hospitals, private practice offices, and drug treatment programs providing HIV-related healthcare and research programs. PARTICIPANTS: A voluntary sample of staff and volunteers from 16 Community Programs for Clinical Research on AIDS units. RESULTS: Factors related to prior TB or a positive skin test at baseline included being foreign-born, increased length of time in health care, living in New York City, or previous bacille Calmette-Guerin vaccination. The rate of PPD conversion was 1.8 per 100 person years of follow-up. No independent relation was found between the amount or type of contact with HIV-infected populations and the risk of TB infection. CONCLUSION: These data provide some reassurance that caring for HIV-infected patients is not related to an increased rate of TB infection among HCWs in these settings.

AIDS-Related Opportunistic Infections↗
PubMed1998

Medical affective computing: medical informatics meets affective computing.

"The need to cope with a changing and partly unpredictable world makes it very likely that any intelligent system with multiple motives and limited powers will have emotions." [1] From advisory systems that understand emotional attitudes toward medical outcomes, to wearable computers that compensate for communication disability, to computer simulations of emotions and their disorders, the research agendas of medical informatics and affective computing--how and why to create computers that detect, convey, and even have emotions--increasingly overlap. Some psychiatric and neurological researchers state their theories in terms of actual or hypothetical computer programs. Adaptive intelligent systems will increasingly rely on emotions to compensate for their own conflicting goals and limited resources--emotional reactions about which psychiatrists and neurologists have special insights. DEP2 (Depression Emulation Program 2) is a computer simulation of adaptive depression--learning from explainable patterns of failure in autobiographical memory--that simulates many depressive behaviors. In the terminology of fault-tolerant computing, adaptive depression involves fault detection (triggered by failure), fault location (strategic retreat and failure diagnosis), and fault recovery (return to on-line operation). DEP2 relies on subsystems whose structures and behaviors are based on popular hypotheses about left and right brain hemispheric function during depression and emotion. DEP2 and its predecessors, DEP and DEPlanner, are relevant to psychiatric and neurological informatics, and to the design of adaptive autonomous robots and software agents.

Adaptation, Psychological↗
PubMed1997

NHS charges. Light on the charge brigade.

Patients charges form a very small part of NHS income. Governments have often used charges to emphasise their commitment to austerity. Knowledge of the effect of charges on public health, equity and eliminating waste is limited. Both Conservative and Labour health ministers have made attempts to abolish charges.

Cost Sharing↗
PubMed1997

Complement component C5 deficiency reduces edema formation in murine ligation-induced acute pancreatitis.

The complement cascade is activated in humans and animals with acute pancreatitis. Activation of complement component C5 liberates C5a, C5a-desarg, and terminal complement complexes (TCCs) that increase capillary permeability, edema, and leukocyte chemotaxis at injured sites. Complement activation plays a major role in pathogenesis of capillary leak and edema formation in severe acute pancreatitis; however, the contribution of C5 (C5a/C5a-desarg, TCCs) has not been defined. Using He gene mutant mice lacking circulating C5, the role of C5 in ligation-induced acute pancreatitis was evaluated. We performed the following experiments: C5-sufficient (Hc1/Hc1) and C5-deficient (Hc0/Hc0) mice had bile and pancreatic ducts ligated. Sham-operated mice had ducts dissected but not ligated. Mice were killed at 4, 8, and 24 hr after bilepancreatic duct ligation. Serologic and morphologic evidences of acute pancreatitis were evaluated. Pancreatic edema was assessed using analysis of pancreatic water content, histologic edema score, and determination of wet weight ratio. After 4, 8, and 24 hr of bile-pancreatic duct ligation, hyperamylasemia and histologic changes of acute pancreatitis were observed in both C5-deficient and C5-sufficient mice. Edema developed in all mice with acute pancreatitis. However, when compared to C5-sufficient mice, mice deficient in C5 developed significantly less pancreatic edema at both 8 and 24 hr of bile-pancreatic duct ligation. This difference was not observed 4 hr after induction of acute pancreatitis. We conclude that C5 contributes to edema formation in murine ligation-induced acute pancreatitis. The presence of an early C5-independent phase, in conjunction with the observation of significant edema in mice deficient in C5, suggests there are other mediators of edema formation in this acute pancreatitis model.

Amylases↗
PubMed1997

Urinary recovery of lactulose compared to D-xylose absorption kinetics in HIV patients with diarrhea and weight loss.

Using a kinetic model of D-xylose absorption, we have previously shown that there is severely impaired absorption of D-xylose in HIV patients with diarrhea and weight loss. The absorptive defect is characterized by an increased rate constant for nonabsorptive loss of D-xylose, Ko, and a decreased absorptive rate constant, Ka, and is unrelated to histology or the presence of pathogens. It is not known if there is also abnormal paracellular transport in these patients. We have extended our observations in these patients by including a measurement of paracellular transport, lactulose absorption. Nine HIV patients with chronic diarrhea, weight loss, and no detectable intestinal pathogens, two healthy volunteers, and three non-HIV patients with chronic diarrhea (two functional and one with scleroderma) were enrolled. Of the nine HIV patients, six had diminished bioavailability of D-xylose, F (range: 19-52%, normal >70%), and elevated rate constant for nonabsorptive loss, Ko (range: 0.54-1.35/hr, normal <0.353/min). Four of the six also had decreased Ka (range: 0.09-0.36/hr, normal >0.634/min). Only one of these six had increased lactulose recovery (3.51%, normal <0.5%). Two of three patients with normal kinetic parameters of D-xylose absorption had increased lactulose urinary recovery (1.92%, 2.61%). In conclusion, lactulose absorption is increased in some patients with HIV-related diarrhea who have normal D-xylose absorption, suggesting a paracellular mechanism for diarrhea in some patients with AIDS enteropathy.

Diarrhea↗
PubMed1997

The safety of ranitidine in over a decade of use.

BACKGROUND: Ranitidine hydrochloride (Zantac) is one of the most extensively studied and widely used drugs of all time. This has provided an excellent opportunity to define its safety profile. METHODS: Data from 189 controlled clinical trials in which more than 26,000 patients received daily doses of ranitidine for 4 weeks or more were reviewed. More than 80% of patients were treated with up to 300 mg ranitidine daily; the remaining patients received doses of up to 1200 mg daily. Eighty-seven trials were placebo controlled. Analyses of post-marketing surveillance and a database of all spontaneously reported adverse events were also evaluated. RESULTS: Overall in the clinical trial programme adverse events were reported by 20% of those receiving ranitidine compared with 27% of those receiving placebo. The pattern of events was similar in all treatment groups with no evidence of dose-related toxicity in regimens encompassing an eightfold range of therapeutic doses. Similarly in a programme of studies designed to evaluate a dose of ranitidine of 75 mg for non-prescription (over-the-counter) use in the treatment of heartburn, ranitidine was not associated with an adverse event profile distinct from that of placebo. Analysis of spontaneously reported adverse event data allowed identification of rare idiosyncratic events. CONCLUSIONS: Review of data from a large population of controlled clinical trials with analyses of postmarketing surveillance studies and spontaneously reported adverse events confirmed the excellent safety profile of ranitidine.

Anti-Ulcer Agents↗
PubMed1996

Is Burkholderia (Pseudomonas) cepacia disseminated from cystic fibrosis patients during physiotherapy?

Burkholderia cepacia is well recognized as a potential respiratory pathogen in cystic fibrosis (CF) patients and there is increasing concern about nosocomial acquisition. Environmental contamination with B. cepacia before, during and after physiotherapy was studied in eight adult CF patients. Air was sampled using a surface air sampler, and horizontal surfaces and pillows were sampled with moistened swabs and contact plates, respectively. Thirty-nine (40%) of 97 air samples were positive and counts ranged from 1-63 cfu/m3. Forty-four percent of samples taken after physiotherapy were positive. B. cepacia was not recovered from sinks or horizontal surfaces but the pillows of three patients were positive. B. cepacia is disseminated into the immediate environment by adult CF patients receiving physiotherapy. The potential risk of person-to-person transmission during hospitalization justifies the recommendation that B. cepacia-positive patients should be segregated from other CF patients.

Adult↗
PubMed1995

Computer modeling of adaptive depression.

Mild, delimited, and adaptive depression may be a specific example of a more general class of mechanism by which intelligent systems--individual, social, and artificial--adapt to dynamic, uncertain, and dangerous environments. Computer modeling, based on connectionist and artificial intelligence planning and learning programming techniques, supports this hypothesis by generating both adaptive behavior and analogs for 10 phenomena associated with depression: global, stable, and internal failure explantation, a cognitive loop of failure rumination, decreased motivation, self-esteem, and self-efficacy, and increased realism, negative generalization, and cognitive change. The idea of adaptive depression can be applied to more than one level of living systems. A better understanding of normal and adaptive depression may lead to a better understanding of clinical depression.

Adaptation, Psychological↗
PubMed1995

Paracelsus confronts the saints: miracles, healing and the secularization of magic.

The sixteenth and seventeenth centuries witnessed an erosion of the role played by the church in healing. Magical practices mediated by the church were replaced by the resources of medicine. This represented an important cultural development and it is often regarded as a manifestation of increasing secularization, the decline of magic and rise of science. This paper examines this issue with special reference to miraculous healing associated with saints, which constituted one of the most important facets of magic controlled by the church. It will be suggested that Paracelsus (Theophrast von Hohenheim, 1493-1541) played an important part in the argument concerning the miraculous powers of saints. Many works by Paracelsus produced at various points in his career were relevant to this issue, but De causis morborum invisibilium, the sequel to his important Opus Paraminum (1531), was especially significant. The question of miraculous healing was therefore important in the first, full presentation of the new system of medicine developed by Paracelsus. Modern commentators have understandably found De causis morborum invisibilium less intelligible and congenial than the more accessible Opus Paramirum. But the former was important to Paracelsus, and it addressed problems that were fundamental to his audience. This case-study shows how conclusions reached by Paracelsus about medical questions were integrally tied up with his theological standpoint and with his wider reaction to the acute crisis of confidence which affected the church and the established social order at the beginning of the sixteenth century. By eliminating the miraculous intervention of saints and promoting the secularization of magic, Paracelsus was contributing to one of the important cultural changes associated with the Reformation.

Christianity↗
PubMed1995

Why Johnny can't reengineer health care processes with information technology.

Many educational institutions are developing curricula that integrate computer and business knowledge and skills concerning a specific industry, such as banking or health care. We have developed a curriculum that emphasizes, equally, medical, computer, and business management concepts. Along the way we confronted a formidable obstacle, namely the domain specificity of the reference disciplines. Knowledge within each domain is sufficiently different from other domains that it reduces the leverage of building on preexisting knowledge and skills. We review this problem from the point of view of cognitive science (in particular, knowledge representation and machine learning) to suggest strategies for coping with incommensurate domain ontologies. These strategies include reflective judgment, implicit learning, abstraction, generalization, analogy, multiple inheritance, project-orientation, selectivity, goal- and failure-driven learning, and case- and story-based learning.

Commerce↗
PubMed1994

Transcription activation by the Escherichia coli cyclic AMP receptor protein. Receptors bound in tandem at promoters can interact synergistically.

Starting with a semi-synthetic Escherichia coli promoter with a binding site for the cyclic AMP receptor protein (CRP) centred between base-pairs 41 and 42 upstream from the transcription start site, a second upstream CRP-binding site, centred between base-pairs 90 and 91, was introduced. CRP binding to this second upstream site results in a several-fold greater stimulation of CRP-dependent transcription initiation, compared to activation at the starting promoter with just one CRP-binding site. Activation of transcription by the upstream CRP molecule is blocked by the HL159 substitution, suggesting that the upstream-bound CRP makes a direct contact with RNA polymerase. Footprinting experiments suggest that RNA polymerase contacts the promoter DNA between the two CRP-binding sites, most likely due to interactions involving the C-terminal part of the alpha subunit. Synergy between tandem bound CRP molecules in transcription activation requires that the two CRP-binding sites be separated by around 40 or 50 base-pairs, but is not found at intermediate spacings. An experiment in which the upstream CRP-binding site is replaced by a site for the related transcription factor, FNR, shows that heterologous synergistic interactions between FNR and CRP are possible.

Bacterial Proteins↗
PubMed1994

Protein kinase C V3 domain mutants with differential sensitivities to m-calpain are not resistant to phorbol-ester-induced down-regulation.

Distinct linker sequences were introduced into the protease-sensitive V3 domain of protein kinase C-alpha and the mutant proteins were expressed in COS-1 cells. Partially purified preparations of these mutants were functionally similar to wild-type protein kinase C-alpha, however their susceptibility to m-calpain was quite distinct, with one mutant being insensitive to cleavage. The three mutants, after expression in COS-1 cells, were found to behave in a manner indistinguishable from wild-type protein kinase C-alpha with respect to subcellular distribution, acute responses to 12-O-tetradecanoyl-phorbol 13-acetate and 12-O-tetradecanoyl-phorbol-13-acetate-induced down-regulation. The data imply that down-regulation of protein kinase C-alpha is likely to involve a general degradative process rather than cleavage by a site-specific protease.

Amino Acid Sequence↗
PubMed1994

Interactions between the Escherichia coli MelR transcription activator protein and operator sequences at the melAB promoter.

The Escherichia coli MelR protein binds to two sites at the melAB promoter and activates transcription in response to melibiose. The binding of purified MelR to the melAB promoter and to a number of derivatives carrying point mutations has been studied. A melAB promoter fragment that is very weakly activated by the melR gene product has been made by creating multiple symmetrical changes in both MelR-binding sites. A library of random substitutions in MelR was screened to find mutants that were able to activate this mutant promoter. One of these mutants contained a substitution in a proposed helix-turn-helix region that most likely relaxes the sequence-specificity of MelR binding. The other mutants contain substitutions throughout the central part of MelR and appear to alter the conformation of MelR, such that activity is triggered at lower melibiose concentrations and by arabinose.

Base Sequence↗
PubMed1994

Saving children during the Depression: Britain's silent emergency, 1919-1939.

The health of a large section of the British population was more adversely affected by the interwar Depression than was acknowledged by official sources. Particular concern was aroused by the condition of women and children. Many new charitable bodies were formed in response to this problem, and these included Save the Children Fund. This paper gives an indication of the scale of the health problem, which was particularly severe in the areas of heavy industry and high unemployment. It then considers the role of charitable organisations in drawing attention to the severity of deprivation and campaigning for appropriate responses on the part of government. Although these pressure groups were energetic and professional in their campaigning, it is conceded that in the short term they exercised only limited influence. However, it is argued that they won the intellectual contest. Finally, it is pointed out that their policies came to be accepted during World War II; thereby organisations like Save the Children Fund contributed to laying the foundations of the modern welfare state.

Charities↗