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Biomedical subjects

G Bird

Publications and source records attributed to G Bird.

At least 19 recordsLinked to original sources
PubMed2006

Molecular chirality and charge transfer through self-assembled scaffold monolayers.

The effect of molecular chirality on electron transmission is explored by photoelectrochemistry. Thiol-terminated chiral scaffold molecules containing a porphyrin chromophore were self-assembled on gold surfaces to form a monolayer. Incorporation of the SAM-coated gold into an electrochemical cell and illumination with visible light generated a cathodic photocurrent. When using circularly polarized light, the photocurrent displayed an asymmetry (different magnitude of photocurrent for right versus left polarization) that changed with the molecular chirality (left- or right-handedness of the scaffold). A symmetry constraint on the electronic coupling between the porphyrin and the organic scaffold is proposed as a possible mechanism for the photocurrent asymmetry.

Journal Article↗
PubMed2005

Somatosensory activations during the observation of touch and a case of vision-touch synaesthesia.

In this study, we describe a new form of synaesthesia in which visual perception of touch elicits conscious tactile experiences in the perceiver. We describe a female subject (C) for whom the observation of another person being touched is experienced as tactile stimulation on the equivalent part of C's own body. Apart from this clearly abnormal synesthetic experience, C is healthy and normal in every other way. In this study, we investigate whether C's 'mirrored touch' synesthetic experience is caused by overactivity in the neural system that responds to the observation of touch. A functional MRI experiment was designed to investigate the neural system involved in the perception of touch in a group of 12 non-synesthetic control subjects and in C. We investigated neural activity to the observation of touch to a human face or neck compared with the observation of touch to equivalent regions on an object. Furthermore, to investigate the somatosensory topography of the activations during observation of touch, we compared activations when observing a human face or neck being touched with activations when the subjects themselves were touched on their own face or neck. The results demonstrated that the somatosensory cortex was activated in the non-synesthetic subjects by the mere observation of touch and that this activation was somatotopically organized such that observation of touch to the face activated the head area of primary somatosensory cortex, whereas observation of touch to the neck did not. Moreover, in non-synesthetic subjects, the brain's mirror system-comprising premotor cortex, superior temporal sulcus and parietal cortex-was activated by the observation of touch to another human more than to an object. C's activation patterns differed in three ways from those of the non-synesthetic controls. First, activations in the somatosensory cortex were significantly higher in C when she observed touch. Secondly, an area in left premotor cortex was activated in C to a greater extent than in the non-synesthetic group. Thirdly, the anterior insula cortex bilaterally was activated in C, but there was no evidence of such activation in the non-synesthetic group. The results suggest that, in C, the mirror system for touch is overactive, above the threshold for conscious tactile perception.

Adult↗
PubMed2000

Systemic lupus erythematosus with C1q deficiency.

We report a case of systemic lupus erythematosus associated with C1q deficiency. Our patient presented at the age of 6 years with cutaneous lupus. She later developed Raynaud's phenomenon, non-scarring alopecia, oral ulceration and grand mal seizures due to cerebral vasculitis. Complement C3 and C4 levels were consistently normal during flares of her lupus and haemolytic activity of her complement was absent, suggesting a deficiency of an early component of the complement cascade. No C1q could be detected.

Alopecia↗
PubMed1999

Coeliac disease in primary care: case finding study.

OBJECTIVES: To provide evidence of underdiagnosis of coeliac disease and to describe the main presenting symptoms of coeliac disease in primary care. DESIGN: Case finding in a primary care setting by testing for coeliac disease by using the endomysial antibody test. SETTING: Nine surgeries in and around a market town in central England, serving a population of 70 000. PARTICIPANTS: First 1000 patients screened from October 1996 to October 1997. OUTCOME MEASURES: Determination of endomysial antibody titre of patients fulfilling the study criteria, followed by small intestine biopsy of those with positive results. RESULTS: The 30 patients (out of 1000 samples) with positive results on the endomysial antibody test all had histological confirmation on small intestine biopsy. The commonest mode of presentation (15/30) was anaemia of varying severity. Most patients (25/30) presented with non-gastrointestinal symptoms. Specificity of the endomysial antibody test was 30/30. CONCLUSIONS: Underdiagnosis and misdiagnosis of coeliac disease are common in general practice and often result in protracted and unnecessary morbidity. Serological screening in primary care will uncover a large proportion of patients with this condition and should be made widely available and publicised. Coeliac disease should be considered in patients who have anaemia or are tired all the time, especially when there is a family history of the disease.

Adult↗
PubMed1998

Coeliac disease in children and adolescents with IDDM: clinical characteristics and response to gluten-free diet.

A total of 167 children and adolescents with insulin-dependent (Type 1) diabetes mellitus (97 males; age range 1.9-22.4 yrs) in a UK paediatric diabetic clinic were screened for coeliac disease using the IgA endomysial (EMA) test, or, in IgA deficient subjects, the IgG antigliadin (AGA) test. Antibody positive subjects were selected for small bowel biopsy, and confirmed coeliac cases started on a gluten free diet. Clinical features, height (Ht) standard deviation score (SDS), body mass index (BMI) SDS, HbA1c, insulin requirements' haemoglobin (Hb), mean red cell volume (MCV), serum folate and ferritin levels were evaluated at diagnosis and thereafter at 3-6 month intervals. A total of 156 subjects (93.4%) were antibody negative. Eleven (6.6%) were antibody positive (10 EMA/1 AGA; 6 males), of whom 9 had biopsies: 1 normal: 8 coeliac (4.8%; 5 males; 1 'classical'; 1 anaemia; 3 'atypical'; 3 asymptomatic). Seven coeliac subjects were followed during 12-24 months of dietary therapy. Pretreatment mean (range) Ht SDS = 0.08 (-1.66 to 1.88); BMI SDS = 0.32 (-0.82 to 1.29); HbA1c = 8.9 (6.2 to 11.3%); insulin dose = 0.98 (0.51 to 1.29) U kg(-1) day(-1). During treatment antibody status reverted to and remained negative, and symptoms resolved. By 24 months, there was a trend towards increased BMI SDS (mean (range) 1.31 (0.47 to 2.29), p = 0.248) and to reductions in HbA1c (8.1 (6.4-10.8), p = 0.697). Repeat small bowel biopsies were normal in 6 subjects (1 refused). No statistically significant changes occurred in any other parameters. In conclusion, serological screening is effective, although the therapeutic benefit of dietary therapy in asymptomatic cases remains uncertain.

Adolescent↗
PubMed1997

Epstein-Barr virus induced virus-associated hemophagocytic syndrome and monoclonal TCR-beta rearrangement: a case report.

Virus-associated hemophagocytic syndrome (VAHS) is a rare histiocytic proliferative disorder secondary to viral infection affecting children and young adults and in which there is both a poor prognosis and no specific treatment. We report a case of VAHS in a 22-year-old woman secondary to infection with Epstein Barr virus in which multiorgan failure developed with a fatal outcome 3 weeks after presentation. Clonal analysis showed EBV incorporation into the T cell genome accompanied by monoclonal rearrangement of the TCR beta gene. Treatment with cyclosporin A resulted in hematological improvement but the patient died of disseminated fungal infection. We propose that bone marrow ablation and allografting should be available for these rare cases and suggest that a protocol should be developed with designated transplant centres to aid early referral.

Adult↗
PubMed1996

D2 dopamine receptor gene TaqI A1 and B1 restriction fragment length polymorphisms: enhanced frequencies in psychostimulant-preferring polysubstance abusers.

Several lines of evidence suggest that presence of a D2 dopamine receptor (DRD2) gene variant marked by TaqI restriction fragment length polymorphisms (RFLPs) might contribute to vulnerability to substance abuse. Psychostimulants display the most robust enhancement of dopamine activity in mesolimbic/mesocortical circuits important for behavioral reward. The present study tests the hypothesis that a DRD2 gene variant might be more prominent in polysubstance users who preferentially use psychostimulants than in addicts with preferential opiate use or in those with no drug preference. Polysubstance users with histories of heavy daily preferential psychostimulant use more often displayed one or two copies of the TaqI A1 (27/62 = 43.5% vs 33/119 = 27.7% for controls), and B1 (20/62 = 32.3% vs 23/119 = 19.8% for controls) markers at the DRD2 locus. DRD2 gene marker distributions in abusers with more prominent opiate use, or those with no history of drug preference, were similar to control genotypes. Psychostimulant-preferring drug users also reported earlier onset of psychostimulant use. Our data are consistent with the hypothesis that DRD2 gene variants marked by these polymorphisms may work, probably in concert with other genetic and environmental factors, to enhance vulnerability to psychostimulant abuse.

Adult↗
PubMed1996

Chemokine levels in human liver homogenates: associations between GRO alpha and histopathological evidence of alcoholic hepatitis.

Alcoholic hepatitis is characterized by parenchymal neutrophil infiltration. Hepatic synthesis of the neutrophil chemokine interleukin-8 (IL-8) is highly elevated in alcoholic hepatitis and levels correlate with the degree of neutrophil infiltration. The aim of this study was to further determine the spectrum of synthesis of chemokines in liver tissue from patients with alcoholic liver disease and a range of disease control subjects. Subjects were composed of 24 patients with alcoholic liver disease of whom 15 had histopathological evidence of alcoholic hepatitis (10 cirrhotic) and 9 no evidence of alcoholic hepatitis (5 cirrhotic); other controls included; normal liver (n = 6), viral hepatitis (n = 16), primary biliary cirrhosis (n = 5), acute liver failure (n = 4), and miscellaneous liver disease (n = 13). Levels of the C-X-C neutrophil chemokine GRO alpha and the mononuclear cell C-C chemokines: macrophage inflammatory protein 1 alpha, macrophage chemotactic protein 1 and RANTES, were determined by ELISA in liver homogenates. Levels of the neutrophil chemokine GRO alpha were specifically elevated (mean 46 pg/mg, compared with normal liver 11 pg/mg) in patients with alcoholic hepatitis. GRO alpha levels correlated with IL-8 levels and were higher in patients with alcoholic liver disease and parenchymal neutrophil infiltration. Hepatic RANTES was elevated in diseased liver, with the highest levels found in viral hepatitis (mean 117 pg/mg, compared with 24 pg/mg in normal liver). No significant changes in hepatic levels of macrophage inflammatory protein 1 alpha (MIP-1 alpha) or macrophage chemotactic protein 1 (MCP-1) were found. These data provide further supportive evidence that parenchymal neutrophil infiltration in alcoholic hepatitis may be determined by selective upregulation of C-X-C chemokine synthesis.

Chemokine CCL2↗
PubMed1995

Device-related, nonintravascular infections.

The intensive care environment is conducive to the transmission of microorganisms because of the array of medical equipment and the frequent contamination of the hands of health care workers. This article reviews recommended nursing interventions for the following nonintravascular devices: automatic implantable cardioverter defibrillators, chest tubes, peritoneal dialysis, enteral nutrition, electronic thermometers, oximeter sensors, and urinary drainage devices.

Catheters, Indwelling↗
PubMed1994

Delayed "all-or-none" activation of inositol 1,4,5-trisphosphate-dependent calcium signaling in single rat hepatocytes.

When single rat hepatocytes were stimulated with the phospholipase C-activating hormone, vasopressin (from 300 pM to 1 microM), the [Ca2+]i signals were always "all-or-none" responses. At low concentrations of vasopressin, Ca2+ release was maximal because liberation of additional inositol 1,4,5-trisphosphate (IP3) by photolysis of its caged precursor at the top of the [Ca2+]i spike failed to increase [Ca2+]i further. However, if IP3 was generated by photolysis of caged IP3 in previously unstimulated cells, [Ca2+]i increased immediately, and the magnitude of the response was a graded function of the quantity of IP3 released. We also analyzed the kinetics of activation of intracellular IP3 receptor/Ca2+ channels by monitoring the quench of sequestered dye by the entry of cytoplasmic Mn2+ into fura-2-loaded intracellular IP3-sensitive organelles. This Mn(2+)-induced quench was precipitous and always preceded by a delay inversely related to the vasopressin concentration. In hepatocytes stimulated with 10 nM vasopressin, IP3 increased slowly, and the half-time of the IP3 rise was comparable with the latency for the release of intracellular calcium. The slow rise in IP3 would be predicted to produce accelerating Ca2+ release. This is consistent with the results of the Mn2+ quench experiments, which revealed accelerating activation of intracellular IP3-regulated calcium channels. We conclude that this accelerating release of Ca2+, which does not occur with instantaneous increases in IP3 due to flash photolysis, is likely to be important for generating the all-or-none Ca2+ mobilization that initiates the processes of intracellular [Ca2+]i oscillations.

Animals↗
PubMed1994

Survey on the use of information sources in the field of aging.

This article presents the results of a survey conducted over the summer of 1992 on the use of information sources by professionals in the field of aging. In particular, factors affecting the use of electronic information sources were investigated. The data provide a demographic profile of North American gerontologists, with a predictably wide range of disciplines and types of practice represented. Several factors were found to have an impact on the gerontologists' utilization of electronic information sources. Respondents who used a larger-than-average number of computer applications were found to make relatively more use of electronic sources, including online searches, CD-ROM indexes, library OPACs, and other databases searched by remote access. Attendance at library workshops was found to increase the amount of end-user searching but not the amount of library-mediated searching. Respondents also reported which databases they used and which they considered most important. MEDLINE was the most frequently mentioned database across all disciplines, including the health and social sciences. Computer databases were ranked least important out of six listed sources of information, and only 5% of respondents reported having used an electronic current awareness profile.

Aging↗
PubMed1993

Circulating and tissue levels of the neutrophil chemotaxin interleukin-8 are elevated in severe acute alcoholic hepatitis, and tissue levels correlate with neutrophil infiltration.

Acute alcoholic hepatitis is characterized by a unique degree of liver neutrophil infiltration, often accompanied by marked peripheral neutrophilia in the absence of demonstrable bacterial or fungal infection. In this study we assayed plasma and tissue levels of a potent neutrophil activator and chemotaxin, interleukin-8, in patients with a spectrum of alcoholic liver diseases and in normal and diseased control subjects. Levels of circulating interleukin-8 were undetectable in normal subjects but highly elevated in patients with alcoholic hepatitis, particularly in those who died (geometric mean = 600 ng/L; confidence interval = 323 to 1,120 vs. geometric mean = 184 ng/L; confidence interval = 114 to 309 in survivors). Levels correlated with biochemical indicators of severe disease (bilirubin: R = 0.38; international prothrombin ratio: R = 0.28; white blood cell count: R = 0.35; creatinine: R = 0.34) and with tumor necrosis factor-alpha (R = 0.43) and soluble tumor necrosis factor receptors (p55; R = 0.59). In contrast, moderate elevations in the levels of circulating interleukin-8 were seen in alcoholic cirrhosis (geometric mean = 93 ng/L; confidence interval = 40 to 213) and in alcoholic patients undergoing alcohol withdrawal (geometric mean = 137 ng/L; confidence interval = 72 to 259). Levels in nonalcoholic inflammatory liver disease were comparatively low (geometric mean = 17 ng/L; confidence interval = 10 to 29).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1992

Activation of the classical complement pathway in spontaneous bacterial peritonitis.

To investigate the possibility that low complement concentrations in the plasma and ascites of patients with severe liver disease could be secondary to complement consumption, complement activation was studied in 32 patients with severe liver disease, 11 of whom had spontaneous bacterial peritonitis (SBP). In patients with SBP, plasma C3 and C4 were significantly lower than in uninfected patients (mean values 0.74 v 1.13 g/l, p less than 0.01 and 0.20 v 0.28 g/l, p less than 0.05 respectively). Plasma complement activation via the classical pathway, as shown by C4d/C4, was significantly increased in patients with SBP compared with uninfected patients (37.3 v 22.2, p less than 0.01) as was C3d/C3 (14.0 v 8.11, p less than 0.01), but there was no significant difference in Ba/B between SBP and uninfected patients. Ascitic C3 concentrations were higher in patients without SBP than in infected patients (0.37 v 0.08 g/l, p less than 0.05), as were factor B values (0.11 v 0.03 g/l, p less than 0.05). There was no significant difference in ascitic C4 concentrations in patients with SBP compared with uninfected patients (0.03 v 0.07 g/l). Although consumption of C3, as shown by C3d/C3 in ascites, was increased in infected patients compared with uninfected patients (79.1 v 36.1, p less than 0.05), there was no difference in ascitic complement activation between the groups for either the classical or alternative pathways. In SBP, decreased plasma C3 and C4 are primarily caused by increased activation of the classical pathway and not impaired hepatic synthesis. Activation and consumption of C3 is one factor causing the low ascitic C3 concentrations observed in SBP.

Adult↗