Biomedical subjects

T Gilbert

Publications and source records attributed to T Gilbert.

At least 19 recordsLinked to original sources

PubMed2004

Endogenous versus exogenous shocks in complex networks: an empirical test using book sale rankings.

We study the precursory and recovery signatures accompanying shocks in complex networks, that we test on a unique database of the Amazon.com ranking of book sales. We find clear distinguishing signatures classifying two types of sales peaks. Exogenous peaks occur abruptly and are followed by a power law relaxation, while endogenous peaks occur after a progressively accelerating power law growth followed by an approximately symmetrical power law relaxation which is slower than for exogenous peaks. These results are rationalized quantitatively by a simple model of epidemic propagation of interactions with long memory within a network of acquaintances. The observed relaxation of sales implies that the sales dynamics is dominated by cascades rather than by the direct effects of news or advertisements, indicating that the social network is close to critical.

Bookselling↗

PubMed2003

Professional discourse and service cultures: an organisational typology developed from health and welfare services for people with learning disabilities.

This study focuses upon the effect of social policy upon a particular area of service provision. It is influenced by the Foucauldian concept of governmentality and the proposition by Lewis et al. that social policy needs to be understood in local contexts. Only through understanding the partial and fragmented impact of policy can we gain a clear insight into the outcomes for users. The study is undertaken through an exploration of the micro politics of organisations providing health and welfare services for people with learning disabilities. It involves an approach to discourse analysis that focuses upon text developed from interviews with service providers, which is brought into contact with published literature in an iterative process. The interpretation of the text produces four themes: power, trust, citizenship and managerialism. The development of these themes and a further holistic interpretation of the text suggest an emerging organisational typology. A typology based upon different articulations of the themes noted that work to produce particular outcomes for service users.

Community Health Services↗

PubMed2002

Entropy production of diffusion in spatially periodic deterministic systems.

This paper presents an ab initio derivation of the expression given by irreversible thermodynamics for the rate of entropy production for different classes of diffusive processes. The first class is Lorentz gases, where noninteracting particles move on a spatially periodic lattice, and collide elastically with fixed scatterers. The second class is periodic systems, where N particles interact with each other, and one of them is a tracer particle that diffuses among the cells of the lattice. We assume that, in either case, the dynamics of the system are deterministic and hyperbolic, with positive Lyapunov exponents. This work extends methods originally developed for a chaotic two-dimensional model of diffusion, the multi-baker map, to higher-dimensional, continuous-time dynamical systems appropriate for systems with one or more moving particles. Here we express the rate of entropy production in terms of hydrodynamic measures that are determined by the fractal properties of microscopic hydrodynamic modes that describe the slowest decay of the system to an equilibrium state.

Journal Article↗

PubMed2001

A soluble class II cytokine receptor, IL-22RA2, is a naturally occurring IL-22 antagonist.

IL-22 is an IL-10 homologue that binds to and signals through the class II cytokine receptor heterodimer IL-22RA1/CRF2-4. IL-22 is produced by T cells and induces the production of acute-phase reactants in vitro and in vivo, suggesting its involvement in inflammation. Here we report the identification of a class II cytokine receptor designated IL-22RA2 (IL-22 receptor-alpha 2) that appears to be a naturally expressed soluble receptor. IL-22RA2 shares amino acid sequence homology with IL-22RA1 (also known as IL-22R, zcytor11, and CRF2-9) and is physically adjacent to IL-20Ralpha and IFN-gammaR1 on chromosome 6q23.3-24.2. We demonstrate that IL-22RA2 binds specifically to IL-22 and neutralizes IL-22-induced proliferation of BaF3 cells expressing IL-22 receptor subunits. IL-22RA2 mRNA is highly expressed in placenta and spleen by Northern blotting. PCR analysis using RNA from various tissues and cell lines showed that IL-22RA2 was expressed in a range of tissues, including those in the digestive, female reproductive, and immune systems. In situ hybridization revealed the dominant cell types expressing IL-22RA2 were mononuclear cells and epithelium. Because IL-22 induces the expression of acute phase reactants, IL-22RA2 may play an important role as an IL-22 antagonist in the regulation of inflammatory responses.

Amino Acid Sequence↗

PubMed2001

Fractality of the hydrodynamic modes of diffusion.

Transport by normal diffusion can be decomposed into hydrodynamic modes which relax exponentially toward the equilibrium state. In chaotic systems with 2 degrees of freedom, the fine scale structures of these modes are singular and fractal, characterized by a Hausdorff dimension given in terms of Ruelle's topological pressure. For long-wavelength modes, we relate the Hausdorff dimension to the diffusion coefficient and the Lyapunov exponent. This relationship is tested numerically on two Lorentz gases, one with hard repulsive forces, the other with attractive, Yukawa forces. The agreement with theory is excellent.

Journal Article↗

PubMed2001

The electronic medical record. A randomized trial of its impact on primary care physicians' initial management of major depression [corrected].

BACKGROUND: Inadequate treatments are reported for depressed patients cared for by primary care physicians (PCPs). Providing feedback and evidence-based treatment recommendations for depression to PCPs via electronic medical record improves the quality of interventions. METHODS: Patients presenting to an urban academically affiliated primary care practice were screened for major depression with the Primary Care Evaluation of Mental Disorders (PRIME-MD). During 20-month period, 212 patients met protocol-eligibility criteria and completed a baseline interview. They were cared for by 16 board-certified internists, who were electronically informed of their patients' diagnoses, and randomized to 1 of 3 methods of exposure to guideline-based advice for treating depression (active, passive, and usual care). Ensuing treatment patterns were assessed by medical chart review and by patient self-report at baseline and 3 months. RESULTS: Median time for PCP response to the electronic message regarding the patient's depression diagnosis was 1 day (range, 1-95 days). Three days after notification, 120 (65%) of 186 PCP responses indicated agreement with the diagnosis, 24 (13%) indicated disagreement, and 42 (23%) indicated uncertainty. Primary care physicians who agreed with the diagnoses sooner were more likely to make a medical chart notation of depression, begin antidepressant medication therapy, or refer to a mental health specialist (P<.001). There were no differences in the agreement rate or treatments provided across guideline exposure conditions. CONCLUSIONS: Electronic feedback of the diagnosis of major depression can affect PCP initial management of the disorder. Further study is necessary to determine whether this strategy, combined with delivery of treatment recommendations, can improve clinical outcomes in routine practice.

Adolescent↗

PubMed2001

Ukrainian application of the Children's Somatization Inventory: psychometric properties and associations with internalizing symptoms.

This paper examines the psychometric properties of the Children's Somatization Inventory (CSI) in 600 10-12-year old children in Kyiv, Ukraine, replicating and extending the original findings from a sample in Nashville, Tennessee (J. Garber et al. 1991). The Kyiv children had significantly lower CSI total scores and reported significantly fewer symptoms than the American children. The Kyiv mothers, however, reported significantly more somatization symptoms in their children than did the American mothers. A factor analysis of the children's data yielded four similar factors encompassing pseudoneurologic, cardiovascular, gastrointestinal, and pain/weakness symptoms. Consistent with the findings from the Nashville study, the CSI was significantly related to the children's self-reports of health and depressive and anxiety symptoms and to maternal reports of child depression and anxiety symptoms. In addition, although more children with the highest CSI scores (25+) reported various illness experiences than those with 0-1 symptoms, no differences were found in the school absentee records. Thus, the results were congruent with the findings of the Nashville study, indicating that the CSI reliably measured somatization in this Ukrainian sample.

Anxiety↗

PubMed2001

Reflective practice and clinical supervision: meticulous rituals of the confessional.

BACKGROUND: Reflective practice and clinical supervision are progressively asserting hegemony upon nursing practice with claims of emancipation and empowerment. However, this is being achieved in an environment where there is little critical debate about the assumptions on which these practices are based. AIM: This paper sets out to challenge the basis upon which reflective practice and clinical supervision are promoted within nursing discourse by employing Michel Foucault's (1982) concept of governmentality. Theme. A broad Foucauldian perspective is used to demonstrate how the technologies of reflective practice and clinical supervision have been accommodated within modern forms of government. These technologies are consistent with the flattened hierarchies and increasing dispersal of practitioners in contemporary health care. In this context reflective practice and clinical supervision can be shown to function in two independent but interrelated ways. First as modes of surveillance disciplining the activity of professionals. Second, as "confessional" practices that work to produce particular identities--autonomous and self-regulating.

Ceremonial Behavior↗

PubMed2001

Overexpression of human insulin-like growth factor binding protein-1 in the mouse leads to nephron deficit.

IGFs and their binding proteins are important regulators of fetal development. We have previously reported that overexpression of the human IGF binding protein-1 in mice is associated with glomerulosclerosis. The aim of this study was to investigate whether, in that model, decreased bioavailability of IGFs also affected nephrogenesis. When the mothers expressed human IGF binding protein-1, pups were growth retarded and had a reduced number of nephrons. Even nontransgenic pups born to heterozygous mothers had a nephron reduction, indicating that renal hypoplasia was secondary to fetal growth retardation. When the transgene was expressed only in the fetus, pups had a normal birth weight and the kidney was normal at birth, as indicated by histologic studies. However, a significant reduction in the nephron number was observed at 3 mo of age. Because nephrogenesis continues for a few days after birth in the mouse, this indicated that human IGF binding protein-1 overexpression altered postnatal nephrogenesis. In addition, exogenously added IGF-II, but not IGF-I, was effective in stimulating in vitro nephrogenesis. Together these elements suggest that reduced amounts of circulating IGFs, presumably IGF-II, impair kidney development.

Animals↗

PubMed2001

Vasovagal syncope: a new treatment for an old problem.

Vasovagal syncope is an extremely common condition that is most often benign. However, in some individuals it can be far more severe, with frequent, sudden, and prolonged episodes of loss of consciousness. The effects can be traumatic, not only from the acute event but from the lifestyle changes that are necessitated by these attacks. We report on the presentation and diagnosis of once such individual and discuss the various treatment options. In addition, supported by recently published evidence, we demonstrate how a pacemaker with rate-drop response is an effective form of treatment.

Adult↗

PubMed2000

Interleukin 21 and its receptor are involved in NK cell expansion and regulation of lymphocyte function.

Cytokines are important in the regulation of haematopoiesis and immune responses, and can influence lymphocyte development. Here we have identified a class I cytokine receptor that is selectively expressed in lymphoid tissues and is capable of signal transduction. The full-length receptor was expressed in BaF3 cells, which created a functional assay for ligand detection and cloning. Conditioned media from activated human CD3+ T cells supported proliferation of the assay cell line. We constructed a complementary DNA expression library from activated human CD3+ T cells, and identified a cytokine with a four-helix-bundle structure using functional cloning. This cytokine is most closely related to IL2 and IL15, and has been designated IL21 with the receptor designated IL21 R. In vitro assays suggest that IL21 has a role in the proliferation and maturation of natural killer (NK) cell populations from bone marrow, in the proliferation of mature B-cell populations co-stimulated with anti-CD40, and in the proliferation of T cells co-stimulated with anti-CD3.

Amino Acid Sequence↗

PubMed2000

Entropy production, fractals, and relaxation to equilibrium

The theory of entropy production in nonequilibrium, Hamiltonian systems, previously described for steady states using partitions of phase space, is here extended to time dependent systems relaxing to equilibrium. We illustrate the main ideas by using a simple multibaker model, with some nonequilibrium initial state, and we study its progress toward equilibrium. The central results are (i) the entropy production is governed by an underlying, exponentially decaying fractal structure in phase space, (ii) the rate of entropy production is largely independent of the scale of resolution used in the partitions, and (iii) the rate of entropy production is in agreement with the predictions of nonequilibrium thermodynamics.

Journal Article↗

PubMed2000

Children's well-being 11 years after the Chornobyl catastrophe.

BACKGROUND: The psychological effects of technological disasters have rarely been studied in children. This study assessed the aftermath of the 1986 Chornobyl disaster in children evacuated to Kyiv from the contaminated zone surrounding the nuclear power facility. METHODS: In 1997, we evaluated three hundred 10- to 12-year-old children in Kyiv who were in utero or infants at the time of the disaster and who had resided near Chornobyl (evacuees) and 300 sex-matched homeroom classmates who had never lived in a radiation-contaminated area. Response rates were 92% (evacuees) and 85% (classmates). Data were obtained from children, mothers, and teachers using standard measures of well-being and risk factors for childhood psychopathology. The children also received physical examinations and basic blood tests. RESULTS: The evacuees and classmates perceived their mental health similarly except for Chornobyl-related anxiety symptoms and perceived scholastic competence. No differences were found on the Iowa Conners' Teacher Rating Scale. Although the physical examination and blood test results were normal, the evacuee mothers rated their children's well-being as significantly worse, especially with respect to somatic symptoms on the Children's Somatization Inventory and Child Behavior Checklist. The most important risk factors for these ratings were maternal somatization and Chornobyl-related stress. CONCLUSIONS: Given the multiple stressful experiences to which evacuee families were exposed, the small differences in the children's self-reports suggest that there are protective factors in the lives of these children. The trauma experienced by the mothers was reflected in their perceptions of their children's well-being, particularly somatic symptoms, but was not transmitted to the children themselves.

Adolescent↗

PubMed2000

Retinoids and nephron mass control.

Advances in the molecular biology of retinoids have provided evidence that vitamin A profoundly influences the differentiation of the whole embryo. In addition to its well-characterized role in primary body axis and central nervous system formation, vitamin A is also required for the ad hoc development of numerous tissues and organs, including the kidney. This review will focus on the emerging evidence that the development of the urogenital tract depends on retinoids. In order to understand the role of vitamin A during kidney development, the mechanisms and sites of retinoic acid production are presented. In addition, an overview of the molecular targets that may be regulated by retinoic acid is included. Together, these elements support the concept that control of vitamin A homeostasis during renal organogenesis might control nephrogenesis via specific gene expression. The clinical impact of variations in vitamin A status during pregnancy is discussed.

Animals↗

PubMed2000

Time- and frequency-resolved photoionisation of the allyl radical

We report picosecond time-resolved pump-probe photoelectron spectra of the allyl radical, C3H5, and the fully deuterated allyl, C3D5, carried out in order to elucidate the primary photophysical processes upon UV excitation. It is shown that the UV bands of allyl decay in a two-step process: the first step is an internal conversion to the lower-lying A-state within 20 ps or less, while the second step is a very fast decay from the A-state to the electronic ground state through a conical intersection. In addition we report the first zero kinetic energy (ZEKE) photoelectron spectrum of allyl, yielding an ionisation energy of 65762 cm-1.

Journal Article↗

PubMed2000

DNA typing of samples for polymarker, DQA1, and nine STR loci from a human body exhumed after 27 years.

A body was exhumed from the ground after 27 years. Samples of femur bone, tooth, and a fingernail were collected and successfully subjected to DNA extraction, quantitation, amplification, and subsequently typed for DQA1, polymarker, and nine STR loci. All three types of samples were typed for D3S1358, vWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S17, D7S820, and amelogenin using ABI Prism 377 DNA sequencer.

Autopsy↗

PubMed1999

Patients with palpitations referred for 24-hour ECG recording.

Palpitations are one of the most common reasons for referral to cardiologists; most are assessed as being medically benign. Eighty consecutive subjects referred for 24-hour ECG recording completed a questionnaire at the time of assessment and a follow-up self-report questionnaire at 18 months. Many of those with and without abnormal hearts reported distress, concern about their symptoms, and limitation of everyday activities. There were few differences between these groups at assessment or at follow-up. There was little change in mental state or in disability in either group over 18 months. Present symptomatic treatment is largely ineffective and there is a need to evaluate psychological and behavioral interventions.

Adrenergic beta-Antagonists↗

PubMed1999

Nephrotoxin exposure in utero reduces glomerular number in sclerosis-prone but not sclerosis-resistant mice.

BACKGROUND: We have previously found that nephron number was not fixed, that is, there was a direct correlation between low birth weight and decreased nephron number in infants. In sclerosis-prone rats, we found that gentamicin exposure in utero induced a reduction in glomerular number and aggravated glomerulosclerosis in adults. In mice, we found that an inborn 50% reduction in nephron number, caused by the Os mutation, was associated with glomerulosclerosis in sclerosis-prone (ROP+/+) mice, but not in sclerosis-resistant (C57BL/6J) mice. Because the genetic background determined the response to decreased nephron number, we asked whether the susceptibility changes in glomerular number and glomerulosclerosis were linked. METHODS: Gentamicin was administered before and after the onset of fetal nephrogenesis. (1) Prior to the onset of nephrogenesis, two groups of pregnant mice were treated from embryonic day (E) E8 to E12. In group A, early glomerular development was studied by placing ureteric ridges removed on E12 in vitro for four days, following which the ureteric bud branches and glomeruli were counted using lectin staining. In group B, nephron number was determined in spontaneously delivered 14-day-old (14PN) pups by counting glomeruli. (2) After the onset of nephrogenesis, to determine the direct effects of gentamicin on nephron induction, ureteric ridges were placed in organ culture at E12 of normal gestation, in the presence or absence of gentamicin. The number of glomeruli and ureteric bud branches were counted after six days in culture. RESULTS: A decrease in glomerular number and ureteric bud branches was observed in sclerosis-prone (ROP+/+) mice, irrespective of whether gentamicin was administered prior to or after the onset of nephrogenesis. Glomerular number and ureteric bud branching were not decreased by gentamicin in sclerosis-resistant (C57BL/6) mice. CONCLUSIONS: These data provide evidence that there is a positive correlation between the susceptibility to glomerulosclerosis in adulthood and a reduction in nephron number in utero. Thus, exposure to nephrotoxins in utero compounds the risk of renal failure as an adult in sclerosis-prone individuals.

Animals↗