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Biomedical subjects

P W Thomas

Publications and source records attributed to P W Thomas.

At least 19 recordsLinked to original sources
PubMed2006

A placebo-controlled, double-blind, randomized controlled trial of a natural killer cell stimulant (BioBran MGN-3) in chronic fatigue syndrome.

BACKGROUND: Previous research has suggested that natural killer (NK) cell activity may be reduced in patients with chronic fatigue syndrome (CFS). AIM: To evaluate the effectiveness of a putative NK cell stimulant, BioBran MGN-3, in reducing fatigue in CFS patients. DESIGN: Randomized, double-blind, placebo-controlled trial. METHODS: We recruited 71 patients with CFS (according to the Centers for Disease Control 1994 criteria) attending an out-patient specialist CFS service. Participants were given oral BioBran MGN-3 for 8 weeks (2 g three times per day) or placebo equivalent. The primary outcome measure was the Chalder physical fatigue score. Self-reported fatigue measures, self-assessment of improvement, change in key symptoms, quality of life, anxiety and depression measures were also included. RESULTS: Data were complete in 64/71 patients. Both groups showed marked improvement over the study duration, but without significant differences. Mean improvement in the Chalder fatigue score (physical scale) was 0.3 (95%CI -2.6 to 3.2) lower in the BioBran group. DISCUSSION: The findings do not support a specific therapeutic effect for BioBran in CFS. The improvement showed by both groups over time highlights the importance of placebo controls when evaluating interventions in CFS.

Adult↗
PubMed2006

The epidemiology of coeliac disease in East Dorset 1993-2002: an assessment of the 'coeliac iceberg', and preliminary evidence of case clustering.

BACKGROUND: Coeliac disease (CD) results from mucosal exposure to dietary gluten in genetically predisposed individuals, although other environmental factors may be involved. The seroprevalence of CD is approximately 1%, with a high ratio of undiagnosed to diagnosed cases, leading to the concept of a 'coeliac iceberg'. AIM: To provide contemporary estimates of the incidence of diagnosed CD and the size of the submerged 'coeliac iceberg', and to seek evidence of disease clustering. DESIGN: Prospective observational study in a defined local population. METHODS: Data were collected prospectively for all biopsy-proven cases diagnosed at Poole Hospital, 1993-2002. Age-specific incidence was calculated and point prevalence estimated for cases within the defined study zone. Evidence of disease clustering was sought using a space-time scan statistic based on a Poisson model. RESULTS: The overall incidence of CD was 8.7 cases/100,000/year (95%CI 7.4-10.1), with a median age at diagnosis of 53 years. Incidence increased progressively during the study period, and the estimated point prevalence of biopsy-proven CD rose from 0.18% to 0.4%. An area of significant space-time clustering was identified, with an incidence of 22.9 cases/100,000/year (95%CI 16.1-31.6), but there was no evidence of seasonality. DISCUSSION: The submerged component of the 'coeliac iceberg' may be diminishing due to increasing case ascertainment, with a projected ratio of undiagnosed to diagnosed cases as low as 1.5:1. Our identification of clustering must be interpreted with caution, but suggests that an additional environmental factor may influence the pathogenesis of CD.

Adolescent↗
PubMed2006

Psychological interventions for multiple sclerosis.

BACKGROUND: The unpredictable, variable nature of Multiple Sclerosis (MS), and the possibility of increasing disability, means that a diagnosis can have substantial psychological consequences. OBJECTIVES: To assess the effectiveness of psychological interventions for people with MS. SEARCH STRATEGY: We searched 19 databases up to December 2004; Cochrane MS Group Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, PsychINFO, CINAHL and 14 others. We searched reference lists of articles, wrote to corresponding authors of the 13 papers identified by June 2004, and searched for trials in progress using 3 research registers. SELECTION CRITERIA: Randomised controlled trials of interventions described as wholly or mostly based on psychological theory and practice, in people with MS. Primary outcome measures were disease specific and general quality of life, psychiatric symptoms, psychological functioning, disability, and cognitive outcomes. Secondary outcome measures were number of relapses, pain, fatigue, health care utilisation, changes in medication, and adherence to other therapies. DATA COLLECTION AND ANALYSIS: Pertinent studies were identified from abstracts by one author. Full papers were independently compared to selection criteria by four authors. Key details were extracted from relevant papers using a standard format, and studies scored on three dimensions of quality. The review is organised into four mini-reviews (MR) dependent on the intervention's target population; people with cognitive impairments (MR1), people with moderate to severe disability (MR2), people with MS (no other criteria) (MR3), and people with depression (MR4). MAIN RESULTS: Overall 16 studies were identified and included. MR1: three trials (n=145). Some evidence of effectiveness of cognitive rehabilitation on cognitive outcomes, although this was difficult to interpret because of the large number of outcome measures used. MR2: three trials (n=80). One small trial suggesting psychotherapy may help with depression. MR3: seven studies (n=688). Some evidence that cognitive behavioural therapy may help people adjust to, and cope with, having MS (three trials). The other trials were diverse in nature and some difficult to interpret because of multiple outcome measures. MR4: three trials (n=93). Two small studies of cognitive behavioural therapy showed significant improvements in depression. AUTHORS' CONCLUSIONS: The diversity of psychological interventions identified indicates the many ways in which they can potentially help people with MS. No definite conclusions can be made from this review. However there is reasonable evidence that cognitive behavioural approaches are beneficial in the treatment of depression, and in helping people adjust to, and cope with, having MS.

Adaptation, Psychological↗
PubMed2005

Characterization of a serodiagnostic complement fixation antigen of Coccidioides posadasii expressed in the nonpathogenic Fungus Uncinocarpus reesii.

Coccidioides spp. (immitis and posadasii) are the causative agents of human coccidioidomycosis. In this study, we developed a novel system to overexpress coccidioidal proteins in a nonpathogenic fungus, Uncinocarpus reesii, which is closely related to Coccidioides. A promoter derived from the heat shock protein gene (HSP60) of Coccidioides posadasii was used to control the transcription of the inserted gene in the constructed coccidioidal protein expression vector (pCE). The chitinase gene (CTS1) of C. posadasii, which encodes the complement fixation antigen, was expressed using this system. The recombinant Cts1 protein (rCts1(Ur)) was induced in pCE-CTS1-transformed U. reesii by elevating the cultivation temperature. The isolated rCts1(Ur) showed chitinolytic activity that was identical to that of the native protein and had serodiagnostic efficacy comparable to those of the commercially available antigens in immunodiffusion-complement fixation tests. Using the purified rCts1(Ur), 74 out of the 77 coccidioidomycosis patients examined (96.1%) were positively identified by enzyme-linked immunosorbent assay. The rCts1(Ur) protein showed higher chitinolytic activity and slightly greater seroreactivity than the bacterially expressed recombinant Cts1. These data suggest that this novel expression system is a useful tool to produce coccidioidal antigens for use as diagnostic antigens.

Antigens, Fungal↗
PubMed2004

Influence of alcohol on cognitive performance during mild hypoglycaemia; implications for Type 1 diabetes.

AIMS: Alcohol and hypoglycaemia independently affect cognitive function. This may be relevant for insulin-treated diabetic patients who drive motor vehicles. The aim of this study was to examine the effect of mild hypoglycaemia (2.8 mmol/l) with modest alcohol intoxication (levels below UK driving limits) on intellectual performance in patients with Type 1 diabetes. METHODS: A hyperinsulinaemic glucose clamp (60 mU/m2) was used to study 17 subjects [age 35 +/- 8 years, HbA1c 8.1 +/- 1.4% (mean +/- sd)] on four occasions: (A) euglycaemia (4.5 mmol/l) with placebo, (B) euglycaemia with alcohol, (C) hypoglycaemia (2.8 mmol/l) with placebo, and (D) hypoglycaemia with alcohol. Cognitive performance was assessed using four-choice reaction time (4CRT, primary outcome), measurements of general intellectual skills [trail making B (TMB) and digit symbol substitution (DSST)], and visual information processing [visual change detection (VCD)]. A test related to driving performance (hazard perception) was also used. RESULTS: In experiments B and D the average blood alcohol level was 43 mg/dl. This was associated with deterioration in 4CRT [+ 35 ms [95% confidence interval (CI) 20, 50]] and TMB, whereas hypoglycaemia without alcohol increased 4CRT only [+ 39 ms (95% CI 5, 73)]. However, when alcohol was combined with hypoglycaemia, there was marked deterioration in all the cognitive function tests [4CRT 74 ms (95% CI 35, 113), TMB, DSST and VCD]. Hazard perception was not affected. The effect of alcohol was no different in euglycaemia than in hypoglycaemia, i.e. there was no interaction. Whereas hypoglycaemia did not reduce the likelihood that the subjects would drive, alcohol did. CONCLUSIONS: The cumulative effect of alcohol and hypoglycaemia on cognitive function together has implications for driving in patients with Type 1 diabetes. Both independently impair cognitive function and together the effects are additive. Patients with Type 1 diabetes should be educated about hypoglycaemia and driving and should avoid alcohol completely if planning to drive.

Adult↗
PubMed2002

The long Bain breathing system: an investigation into the implications of remote ventilation.

A long version of the Bain breathing system is commonly used when remote anaesthesia is required, such as during magnetic resonance imaging or radiotherapy. We compared the static compliance and distal pressures over a range of flows in a 1.6 and 9.6 m Bain system. We examined the effect on ventilation of increasing the length of the Bain system in lung models for 10, 20 and 70 kg patients. We found that static compliance was increased in the long Bain system. We found that with matched peak inspiratory ventilator pressures there was a reduction in peak inspiratory pressures at the patient end with the longer system (p < 0.001). A reduction in tidal volume was found with the 9.6 m Bain (p < 0.001), and positive end-expiratory pressure was increased (p = 0.01). Although the effect on tidal volume was proportionally small in the 70 kg simulation (660 and 617 ml in 1.6 and 9.6 m systems, respectively) it increases in significance in children, with a 23% reduction in tidal volume in the 10 kg mock lung (95 and 73 ml in 1.6 and 9.6 m systems, respectively). Anaesthetists should be aware of the reduction in tidal volume and increased positive end-expiratory pressure. During remote anaesthesia with a long Bain system, the ventilator should be adjusted to compensate.

Adult↗
PubMed2001

G-quadruplex DNA binding by a series of carbocyanine dyes.

We have examined a number of carbocyanine dyes for their ability to bind intramolecular G-quadruplex DNA structures (G4'-DNA) using a Taq polymerase stop assay. Of the five dyes examined, only one, N,N'-diethylthiacarbocyanine iodide (DTC), was found to bind to G4'-DNA. DTC was also the only dye found to inhibit human telomerase at 50 microM concentration.

Binding Sites↗
PubMed2000

Disruption of the gene which encodes a serodiagnostic antigen and chitinase of the human fungal pathogen Coccidioides immitis.

Disruption of genes in medically important fungi has proved to be a powerful tool for evaluation of putative virulence factors and identification of potential protein targets for novel antifungal drugs. Chitinase has been suggested to play a pivotal role in autolysis of the parasitic cell wall of Coccidioides immitis during the asexual reproductive cycle (endosporulation) of this systemic pathogen. Two chitinase genes (CTS1 and CTS2) of C. immitis have been cloned. Preliminary evidence has suggested that expression of CTS1 is markedly increased during endospore formation. The secreted CTS1 chitinase has also been shown to react with patient anti-Coccidioides complement-fixing (CF) antibody and is a valuable aid in the serodiagnosis of coccidioidomycosis. To examine the role of CTS1 in the morphogenesis of parasitic cells, the CTS1 gene was disrupted by a single, locus-specific crossover event. This resulted in homologous integration of a pAN7.1 plasmid construct that contained a 1.1-kb fragment of the chitinase gene into the chromosomal DNA of C. immitis. Results of Southern hybridizations, immunoblot analyses of culture filtrates using both CTS1-specific murine antiserum and serum from a patient with confirmed coccidioidal infection, an immunodiffusion test for CF antigenicity, and substrate gel electrophoresis assays of chitinase activity confirmed that the CTS1 gene was disrupted and nonfunctional. This is the first report of a successful targeted gene disruption in C. immitis. However, loss of CTS1 function had no effect on virulence or endosporulation. Comparative assays of chitinase activity in the parental and Deltacts1 strains suggested that the absence of a functional CTS1 gene can be compensated for by elevated expression of the CTS2 gene. Current investigations are focused on disruption of CTS2 in the Deltacts1 host to further evaluate the significance of chitinase activity in the parasitic cycle of C. immitis.

Animals↗
PubMed2000

Height and weight reference curves for homozygous sickle cell disease.

OBJECTIVE: To derive height and weight growth reference curves for children with homozygous sickle cell disease. STUDY DESIGN: Subjects (n = 315) were participants in a population based, longitudinal cohort study of sickle cell disease in Kingston, Jamaica. Regular measurements of height and weight were made from enrollment into the study at birth up to 22 years of age. RESULTS: Sex specific growth reference curves for height for age and weight for age covering the age range 0-18 years are presented. CONCLUSION: These growth reference curves are suitable for identifying coincidental growth problems in children with homozygous sickle cell disease.

Adolescent↗
PubMed1999

Isolation and confirmation of function of the Coccidioides immitis URA5 (orotate phosphoribosyl transferase) gene.

The OPRTase (URA5) gene of the human pathogenic fungus, Coccidioides immitis (Ci), was cloned, sequenced, chromosome-mapped and expressed both by transformation of Escherichia coli and by complementation of wdura5Delta, an auxotrophic strain of Wangiella dermatitidis (Wd) with a disrupted URA5 gene. A functional assay of the recombinant URA5 expressed by E. coli was conducted to ensure that the isolated Ci gene encodes the appropriate enzyme. In the absence of a transformation system for Ci, we also used a reported method of introduction of heterologous DNA into cells of the phylogenetically related fungus, Wangiella dermatitidis, to confirm the function of the Ci URA5 gene. Both the genomic and cDNA sequences of the Ci URA5 gene are presented. The transcription start point and two poly(A) addition sites were confirmed. The gene contains a 714-bp ORF that translates a 238-amino-acid (aa) protein of 25.5kDa and pI of 6.5. No introns are present. The translated protein contains a single, putative N-glycosylation site. The deduced Ci protein showed 55-63% aa sequence similarity to reported fungal OPRTases. The URA5 gene was mapped to chromosome IV of Ci, and was shown to be a single copy gene by Southern and Northern hybridizations. Transformation of the wdura5Delta mutant to prototrophy was accomplished by electroporation of Wd yeast cells with the Ci URA5 gene. Cellular uptake of the heterologous DNA was confirmed by Southern hybridization. The stable transformants were unable to grow on a medium containing 5-FOA. Expression of the Ci URA5 gene can be used as a selectable marker for a transformation system, and the latter is essential for molecular studies of this pathogenic fungus.

Amino Acid Sequence↗
PubMed1999

Postsplenectomy course in homozygous sickle cell disease.

OBJECTIVE: To determine whether children with homozygous sickle cell (SS) disease and splenectomy are at greater risk of death, overwhelming septicemia, or other complications. METHODS: A total of 130 patients with SS treated by splenectomy (46 recurrent acute splenic sequestration, 84 chronic hypersplenism) over a 22.5-year period at the Sickle Cell Clinic of the University Hospital of the West Indies, Kingston, Jamaica, were compared with a control group matched for sex, age, and duration of follow-up in a retrospective review. Deaths and bacteremias were examined over the whole study period. Painful crises, acute chest syndromes, and febrile episodes were compared in the 90 patients completing 5 years of postsplenectomy follow-up. FINDINGS: Mortality and bacteremic episodes did not differ between the splenectomy and control groups. Painful crises were more common in the splenectomy group than in the control group (P =.01) but did not differ between splenectomy indications. Acute chest syndrome was more common in the splenectomy group than in the control group (P <.01) and was more common in the acute splenic sequestration group than in the hypersplenism group (P =.01). Febrile events did not differ between the groups or between the indications for splenectomy. CONCLUSION: Splenectomy does not increase the risk of death or bacteremic illness in patients with SS disease and, if otherwise indicated, should not be deferred for these reasons.

Adolescent↗
PubMed1999

Pulmonary haemorrhage after percutaneous paravertebral block.

We describe the management of a 65-yr-old woman anaesthetized for thoracotomy. The patient suffered a pulmonary haemorrhage after percutaneous paravertebral injection performed using the loss of resistance to saline technique. Thoracotomy at a later date revealed that the lung tissue had become adherent to the chest wall and that the paravertebral space was fibrosed secondary to previous surgery. This particular complication of percutaneous paravertebral block has not been reported previously and raises the question of risk vs benefit of this pre-emptive analgesic technique.

Aged↗
PubMed1998

Comparison of responses evoked by mild indirect cooling and by sound in the forearm vasculature in patients with homozygous sickle cell disease and in normal subjects.

In normal individuals, novel or noxious stimuli commonly evoke the pattern of the alerting or defence response which includes cutaneous vasoconstriction, but vasodilatation in forearm skeletal muscle. We have compared cardiovascular responses evoked by sound and by indirect cooling in 60 patients with homozygous sickle cell (SS) disease and in 30 control subjects with normal haemoglobin genotype (AA). A sound of 90 dB, 1 kHz for 30s evoked an increase in hand and forearm cutaneous vascular resistance (HCVR and FCVR) in SS patients and an increase in HCVR in AA subjects, as assessed from Doppler flowmetry. Meanwhile, a decrease in forearm vascular resistance (FVR) assessed by venous occlusion plethysmography, occurred in 14 out of 30 AA subjects and 25 out of 60 SS patients, indicating vasodilatation in forearm muscle; an increase in FVR occurred in the remainder. The proportions of SS patients and AA subjects who showed an increase in FVR (53% vs 57%) were not significantly different. Cooling increased HCVR and FCVR in SS patients and increased FCVR in AA subjects; a decrease in FVR indicating vasodilatation, occurred in 12 out of 30 AA subjects, but in only 10 out of 60 SS patients. The proportion of SS patients who showed an increase in FVR to cooling was greater than in AA subjects (83% vs 60%, P < 0.05). Thus, SS patients are just as capable of showing the muscle vasodilatation of the alerting response to sound as AA subjects. That few SS patients showed muscle vasodilatation in response to cooling is consistent with the view that reflex vasoconstrictor responses to cooling are particularly strong in SS patients. This, in turn, is consistent with our hypothesis that the reflex vasoconstrictor response to cooling acts as a trigger for the painful crisis of SS disease by diverting blood flow away from active bone marrow.

Acoustic Stimulation↗
PubMed1998

Peripheral vascular response to mild indirect cooling in patients with homozygous sickle cell (SS) disease and the frequency of painful crisis.

1. In homozygous sickle cell (SS) disease, skin cooling is a common precipitating factor of the painful crisis which is associated with avascular necrosis of active bone marrow. Since skin cooling does not directly induce sickling, we have investigated the nature of the reflex vascular responses to mild cooling in SS patients in a steady state of the disease and compared them with their history of painful crises. 2. Experiments were performed in Jamaica on 60 male SS patients and 30 matched control subjects with normal haemoglobin (AA) genotype. Forearm blood flow (FBF) was measured by venous occlusion plethysmography and mean arterial pressure (MAP) by a Finapres device: forearm vascular resistance (FVR) was calculated as MAP/FBF. Cutaneous erythrocyte flux in forearm and hand was monitored by a laser Doppler meter. The contralateral hand was immersed in cool water at 16 degrees C for 2 min, 6 times, at random intervals of 0.5-3 min. 3. The first cool immersion evoked an increase in MAP, cutaneous vasoconstriction and a net increase in FVR in both AA and SS subjects. However, the direction of change in FVR varied between individuals such that 18 AA subjects showed an increase in FVR (constrictor group) while 12 showed a decrease in FVR, indicating vasodilatation in forearm muscle (dilator group). In contrast, 50 SS subjects showed an increase in FVR and only 10 showed a decrease in FVR. The proportion of subjects who showed net vasoconstriction was significantly greater in the SS than in the AA group (83% versus 60%, P = 0.03, chi 2 test). 4. By the sixth cool stimulus, the 'dilator' group of AA subjects showed no change in FVR while the 'dilator' group of SS patients showed an increase in FVR. We suggest that forearm muscle vasodilatation was the characteristic component of the alerting/defence response to novel or noxious stimuli which habituates on repetition. 5. In the whole group of SS patients, baseline values of cutaneous vascular resistance and FVR increased between stimuli, indicating persistent vasoconstriction, and the sixth cool stimulus still evoked cutaneous vasoconstriction and a net increase in FVR. In contrast, AA subjects showed an increase in baseline FVR between stimuli, but the sixth cool stimulus had no significant effect on cutaneous vascular resistances, or FVR. 6. In SS patients there were no associations between the direction of change in FVR evoked by the first cool stimulus and forearm circumference or skinfold thickness, concentrations of haemoglobin or fetal haemoglobin. However, the frequency of painful crises was significantly greater in the 'constrictor' group than in the 'dilator' group (0.36 versus 0.12/year, P = 0.04, Mann-Whitney test). 7. These results indicate that the primary reflex vasoconstrictor response evoked by mild cooling is stronger and more persistent in SS patients than in AA subjects and is particularly strong in SS patients who are most prone to painful crises. The results are consistent with the hypothesis that skin cooling may precipitate the painful crisis by causing reflex vasoconstriction in muscle, and possibly in bone marrow, so diverting blood flow away from the active marrow.

Acute Disease↗
PubMed1998

Immunogenicity of a 48-kilodalton recombinant T-cell-reactive protein of Coccidioides immitis.

The outcome of coccidioidomycosis depends to a large extent on the effectiveness of the T-cell-mediated immune (CMI) response to the fungal pathogen. For this reason, identification of Coccidioides immitis antigens which stimulate T cells is important for understanding the nature of host defense against the organism and essential for the development of an effective vaccine. Here we describe the immunogenicity of a 48-kDa T-cell-reactive protein (TCRP). The antigen is expressed by parasitic cells and localized in the cytoplasm. It stimulates the proliferative response and production of gamma interferon by T cells of mice immunized with C. immitis spherules. Specific antibody reactive with the recombinant TCRP (rTCRP) was detected in sera of patients with confirmed coccidioidal infection, and the highest titers of antibody to the recombinant protein correlated with elevated titers to the serodiagnostic complement fixation antigen of C. immitis. These results suggest that the TCRP is presented to the host during the course of infection. Immunization of BALB/c and C3H/HeN mice with the rTCRP affords a modest but significant level of protection against an intraperitoneal challenge with C. immitis. It is suggested that the rTCRP may be able to contribute to a multicomponent vaccine designed to stimulate CMI response against the parasitic cycle of C. immitis.

Amino Acid Sequence↗
PubMed1997

Microchromatographic quantitation of hemoglobin A levels in phenotypes of sickle cell-beta(+) thalassemia.

The inheritance of the sickle cell gene in combination with a gene for beta(+) thalassemia results in a spectrum of sickle cell-beta(+) thalassemia syndromes with varying levels of hemoglobin A (HbA). Some severe sickle cell-beta(+) thalassemia syndromes have small amounts of HbA, which may be difficult to quantitate in the presence of fetal hemoglobin. A microcolumn chromatographic method, using 0.5 M Tris-acetic acid developers with varying pH values from 9.0 to 6.0, appears to adequately quantitate small amounts of HbA. This method is relatively simple and cheaper than high-performance liquid chromatography, a major consideration in developing countries.

Chromatography↗
PubMed1997

The hsp60 gene of the human pathogenic fungus Coccidioides immitis encodes a T-cell reactive protein.

A heat shock protein-encoding gene (hsp60) from the human respiratory fungal pathogen, Coccidioides immitis (Ci), was cloned, sequenced, chromosome-mapped, expressed and immunolocalized in parasitic cells. Both the genomic and cDNA sequences are presented. The transcription start point and poly (A) addition site were confirmed. The hsp60 gene contains two introns and a 1782-bp ORF which translates a 594-amino acid (aa) protein of 62.4 kDa and pI of 5.6. The translated protein revealed two potential N-glycosylation sites. The deduced HSP60 showed 78-83% aa sequence similarity to reported fungal HSP60 proteins. The hsp60 gene was mapped to chromosome III of Ci and was shown to be a single copy gene by Southern and Northern hybridization. Expression of a 1737-bp cDNA fragment of the hsp60 gene in E. coli resulted in production of a recombinant protein. Amino acid sequence analysis of the recombinant protein confirmed that it was encoded by the Ci hsp60 gene. Antiserum raised in mice against the isolated recombinant protein immunolocalized HSP60 in the cytoplasm and wall of parasitic cells of Ci. The recombinant HSP60 was used to immunize BALB/c mice and was shown to induce proliferation of T cells isolated from lymph nodes of these animals. The hsp60 gene of Ci is the first reported heat-shock protein gene of this human pathogen.

Amino Acid Sequence↗