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Biomedical subjects

A Beckett

Publications and source records attributed to A Beckett.

At least 19 recordsLinked to original sources
PubMed2005

Diagnosis of duck circovirus infections by conventional and real-time polymerase chain reaction tests.

Development of the first conventional and real-time polymerase chain reaction (PCR) tests for the diagnoses of duck circovirus (DuCV) infections is described. Both tests amplified a 230 bp fragment specific to the DuCV Rep gene. Although both tests had the same detection limit (13 x 10(3) target DNA/ml) when the target DNA was diluted in water, the detection limit of the real-time test (13 x 10(4) target DNA/ml) was 10-fold less than the conventional test (13 x 10(5) target DNA/ml) when the amplifications were performed in the presence of cellular DNA. Using the conventional PCR test, DuCV DNA was detected in 85 (84%) of 101 bursa of Fabricius samples from dead or sick ducks, aged between 1 and 12 weeks, and in samples from 35 (94%) of 37 flocks. Application of the SYBR Green-based real-time PCR test to 54 selected bursa of Fabricius samples indicated that more samples were positive by real-time PCR than by conventional PCR, allowed the numbers of genome copies to be estimated and showed that some bursa of Fabricius samples contained over 10(13) genome copies/g tissue. Although DuCV infections were detected in birds aged from 1 to 12 weeks, higher virus DNA levels were detected in ducks aged older than 5 weeks than in ducks younger than 5 weeks. An in situ hybridization method for the detection of DuCV in histological samples was also developed. Additional work is required to determine the clinicopathological significance of DuCV infections.

Animals↗
PubMed2005

Lymphocyte contamination of laryngoscope blades--a possible vector for transmission of variant Creutzfeldt-Jakob disease.

Variant Creutzfeldt-Jakob disease (vCJD) is associated with extensive prion infection of lymphoreticular tissues during the prolonged asymptomatic incubation period. Instruments exposed to infected tissues of preclinically infected individuals during medical or surgical procedures represent a potential risk of iatrogenic transmission of vCJD prions. We assessed the frequency of contamination with lymphoid tissue of single-use laryngoscope blades used for tracheal intubation for general anaesthesia. Using a cyto-centrifugation technique, lymphocytes were detected from 30% of laryngoscope blades studied. As prions resist routine sterilisation procedures, the use of non-disposable laryngoscope blades poses a risk of transmitting vCJD from patient to patient. The use of such instruments should be abandoned and disposable alternatives used.

Anesthesia, General↗
PubMed2004

Parallel changes in bladder suburothelial vanilloid receptor TRPV1 and pan-neuronal marker PGP9.5 immunoreactivity in patients with neurogenic detrusor overactivity after intravesical resiniferatoxin treatment.

OBJECTIVE: To compare PGP9.5 and transient receptor potential vanilloid receptor (TRPV1) suburothelial immunoreactivity between controls and patients with spinal neurogenic detrusor overactivity (NDO) before and after treatment with intravesical resiniferatoxin, as suburothelial PGP9.5-staining nerve fibres decrease in patients with spinal NDO who respond to intravesical capsaicin, and TRPV1 is present on these suburothelial nerve fibres in normal and overactive human urinary bladder. PATIENTS AND METHODS: Patients with refractory NDO were enrolled in a prospective, randomized, parallel-group, double-blind, placebo-controlled trial using escalating doses of resiniferatoxin to a maximum of 1 micro mol/L. Flexible cystoscopic bladder biopsies obtained at baseline, 4 weeks after each instillation and at the time of maximum clinical response were compared with biopsies taken from control subjects. Frozen sections were incubated with rabbit antibodies to TRPV1 and PGP9.5, and assessed using standard immunohistochemical methods. PGP9.5 nerve density was analysed using a nerve-counting graticule by an observer unaware of sample origin. Another two independent observers unaware of each other's results used a random grading scale to evaluate TRPV1 nerve fibre density and intensity. The immunohistochemistry results were compared with histology findings (haematoxylin-eosin), and the Mann-Whitney test used to assess any differences (P < 0.05 significant) and the Pearson test for correlation. RESULTS: There were eight controls and 20 patients with spinal NDO, 14 (five clinical responders and nine not) who received the maximum dose of resiniferatoxin. There were more PGP9.5 and TRPV1 nerve fibres in patients with NDO than in controls (P = 0.007 and 0.002, respectively). Immunoreactivity before resiniferatoxin was similar in both groups for both PGP9.5 and TRPV1. In responders there were fewer PGP9.5 and TRPV1-positive fibres after treatment (P = 0.008 for each) but no change in those not responding. Changes after treatment for TRPV1 correlated well with those for PGP9.5 (r = 0.88, P < 0.001). CONCLUSIONS: The decrease of PGP9.5 and TRPV1 immunoreactive nerve fibres in responders to resiniferatoxin (to levels in control tissues) suggests that the increased numbers of nerve fibres in patients with NDO are mainly of sensory origin and express TRPV1. As baseline nerve fibre values were similar in responders and nonresponders, an additional factor may account for the difference in treatment outcome.

Administration, Intravesical↗
PubMed2000

Microdysgenesis with abnormal cortical myelinated fibres in temporal lobe epilepsy: a histopathological study with calbindin D-28-K immunohistochemistry.

Microdysgenesis is a microscopic cortical malformation reported to occur with varying incidence in surgical lobectomies from patients with temporal lobe epilepsy (TLE). It may act as a substrate for the seizures. Four patients are reported with TLE, hippocampal sclerosis and cortical microdysgenesis which was also characterized by the presence of abnormal myelinated fibres running tangentially in the superficial cortical laminae and closely associated with abnormal clusters of neurones. Similar abnormal cortical fibres have been described in other malformations of cortical development including polymicrogyria and focal cortical dysplasia and it is therefore likely that these fibres represent part of the microdysgenetic malformation not hitherto reported. The possibility is discussed that they may also be of functional significance in terms of influencing local seizure propagation and the secondary cortical neuronal loss observed, predominantly affecting layer II. Studies of calbindin interneuronal populations showed preservation of these cells in the microdysgenetic cortex, when compared with non-malformed temporal lobes, despite an overall reduction in cortical neuronal density. In addition, prominent numbers of neurogliaform calbindin-positive nerve cells were observed in the microdysgenesis cases and the nature of these cells is speculated upon.

Adult↗
PubMed2000

The effect of intravesical capsaicin on the suburothelial innervation in patients with detrusor hyper-reflexia.

OBJECTIVE: To determine the effect of intravesical capsaicin on the suburothelial innervation in patients with detrusor hyper-reflexia, in whom a single dose of intravesical capsaicin (1-2 mmol/L) increases the bladder capacity for 3-6 months. PATIENTS AND METHODS: Thirteen patients with detrusor hyper-reflexia underwent cystometry and had flexible cystoscopic biopsies taken before and 6 weeks after receiving instillations of intravesical capsaicin (1 mmol/L). Similar biopsies were also obtained from a control group of 12 neurologically normal patients with microscopic haematuria and normal bladders. Frozen sections were stained using antibodies to S100 and PGP 9.5. Using computerized analysis, the mean nerve density scores were expressed as nerves/mm2 for S100-positive structures and 'red%' and 'red in frame' for PGP 9.5. RESULTS: The mean (SEM) functional bladder capacity increased from 193.2 (28.17) mL before to 396.3 (41.96) mL at 6 weeks after treatment with capsaicin, in nine of the 13 patients. The mean nerve density of S100-positive structures in the control group was 83 (3.18) nerves/mm2. In hyper-reflexic patients who responded to capsaicin by improved bladder capacity, the mean nerve density of S100-positive structures was reduced from 100 (12.2) before to 66 (9.4) nerves/mm2 6 weeks after treatment. In those who did not respond to capsaicin there was no significant difference in these scores. Similarly the 'red%' and 'red in frame' reduced from 3.41 (1.06) to 1.15 (0.32) and 824.7 (246.3) to 297.9 (83.5) units, respectively, before and 6 weeks after capsaicin treatment. The difference in those not responding was not significant. CONCLUSIONS: Intravesical capsaicin causes a reduction in suburothelial nerve densities in the bladder of patients with detrusor hyper-reflexia. This may explain its prolonged beneficial effect in these patients.

Administration, Intravesical↗
PubMed1998

Treating the human bladder with capsaicin: is it safe?

OBJECTIVES: Although human contact with capsaicin has occurred over thousands of years, some uncertainty surrounds its status as a possible carcinogen. This is the first report of bladder biopsies from patients who have been treated with capsaicin over a 5-year period. METHODS: Between 1991 and 1996, 20 patients (9 males, 11 females; mean age 52.5 years, range 40-70 years) with intractable detrusor hyperreflexia have had repeated instillations of intravesical capsaicin (1-2 mmol/l). The number of treatments per patient varied between 1 and 17 (total = 82; average 6/patient). The surveillance programme involved repeated flexible cystoscopy and bladder biopsies before and after capsaicin. Cryostat sections were stained with haematoxylin-eosin and examined by light microscopy. RESULTS: None of the bladder biopsies have shown metaplasia, dysplasia, flat carcinoma in situ, papillary or solid invasive cancer. CONCLUSIONS: No pre-malignant of malignant change has been found in biopsies of patients who had repeated capsaicin instillations for up to 5 years. However, as the morphological effects of chemical carcinogens may not be apparent for 10 years, further surveillance is being continued.

Adult↗
PubMed1997

Spontaneous epileptiform seizures but increased resistance to kindled seizures in a mutant Sprague-Dawley rat (mf/mf).

Approximately 30% of a breeding colony of Sprague-Dawley rats homozygous for an autosomal recessive mutation mf ("mutilated foot") associated with a peripheral sensory neuropathy have been found unexpectedly to suffer spontaneous epileptiform attacks. Seizures ranged from brief episodes of compulsive running to tonic-clonic convulsions lasting for up to 30 s, recurring at intervals of hours or days. EEG recordings during seizures showed high-voltage 8-10 Hz spike trains that abated over the ensuing 1-2 min. Interictal records were usually normal. Twice-daily kindling of the amygdala (200 microA sinewave for 1.0 s) was unexpectedly ineffective. Most of the rats that had suffered spontaneous seizures failed to develop kindled afterdischarges, even after 30 kindling stimulations. Other mf rats developed prolonged high-amplitude kindled afterdischarges that were arrested at stage 2 and failed to evolve into convulsive seizures. Hippocampal dentate granule cells of kindled mf rats, stained for zinc by Timm's method, showed significantly less mossy fibre sprouting than wild-type Sprague-Dawley rats after the same number of kindled afterdischarges. A minority of the mf rats tested (2 of 14) kindled normally. Auditory stimulation (n = 23) or stroboscopic flicker (n = 14) failed to elicit seizures or running fits in any mf rat. Peripheral neuropathy corresponding to that in the mf rat, with resistance to kindling and diminished mossy fibre sprouting, have also been reported in transgenic mice with defective p75NGFR neurotrophin receptors. A homologous genetic defect in the rat could account for most of the features of the mf phenotype.

Acoustic Stimulation↗
PubMed1994

An immunohistochemical study of p53 and proliferating cell nuclear antigen expression in progressive multifocal leukoencephalopathy.

Nuclear p53 immunoreactivity is demonstrated in infected oligodendroglia, as well as in a proportion of reactive and bizarre astrocytes, in seven progressive multifocal leukoencephalopathy (PML) biopsies. This likely represents binding to, and prolongation of the half-life of, wild-type p53 protein by JC virus T-antigen. Other possible mechanisms are considered. The same cells show proliferating cell nuclear antigen (PCNA) positivity, as do a proportion of morphologically normal oligodendroglia and astrocytes, reflecting proliferating populations of these glial sub-types. It is possible that functional inactivation of p53 in nonlytically infected astrocytes may allow neoplastic astrocyte clones to emerge. However, p53 and PCNA immunoreactivity per se cannot be regarded as indicative of neoplasia in PML, and caution must be exercised in the interpretation of such nuclear staining profiles.

Adult↗
PubMed1990

Neuropsychiatric manifestations of HIV infection.

In addition to physical and psychological effects, HIV infection can produce neuropsychiatric signs and symptoms. Clinicians working with HIV-infected patients should be familiar with the multiple pathological changes with which it can be associated.

AIDS Dementia Complex↗
PubMed1990

Treating persons with ARC and AIDS in group psychotherapy.

The authors describe a range of critical issues that are common within homogeneously composed groups for patients suffering from Acquired Immunodeficiency Syndrome (AIDS) and AIDS Related Complex (ARC). They examine the need for these patients to understand their physical symptomatology, to reconsider life's priorities, and to confront their ethical and moral dilemmas. The authors also highlight special effects, unique group atmosphere and process, and the nature of the group contract that is essential for these patients.

AIDS-Related Complex↗
PubMed1986

Clonazepam blockade of spontaneous and CO2 inhalation-provoked panic in a patient with panic disorder.

A 30-year-old woman with panic disorder and phobic avoidance responded partially to treatment with alprazolam but recovered fully while receiving clonazepam, which blocked her panic attacks and anticipatory anxiety. Before treatment, the patient underwent a carbon dioxide inhalation test as a challenge and sustained a full-featured panic attack. After clonazepam therapy and retesting under identical conditions, no panic attack was reported. This is the first report of provoked panic blocked by clonazepam, a putative, clinically effective antipanic agent.

Adult↗
PubMed1983

Effects of hydration on the surface morphology of urediospores.

Changes in the surface morphology of mature urediospores of Uromyces viciae-fabae have been studied with respect to different preparative procedures for the scanning electron microscope. Specimens were examined in the critical point-dried, freeze-dried and frozen-hydrated states. Dried urediospores were significantly different in appearance from those which were hydrated. Shrinkage probably accounted for some of the surface features of dried spores, particularly amongst those which had been critical point-dried. No significant effects on spore surface texture resulted from chemical immersion fixation, chemical vapour fixation, dehydration or the mode of sputter-coating. It is suggested that the presence or absence of unfreezable water, involved in maintaining the structural stability of polymers which provide the specimen surface with its characteristic morphology, may have an important influence on the gross texture of cell surfaces as viewed with the scanning electron microscope.

Fixatives↗