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K Bull

Publications and source records attributed to K Bull.

14 recordsLinked to original sources
PubMed2005

Development of a new photocatalytic oxidation air filter for aircraft cabin.

UNLABELLED: A new photocatalytic oxidation air filter (PCO unit) has been designed for aircraft cabin applications. The PCO unit is designed as a regenerable VOC removal system in order to improve the quality of the recirculated air entering the aircraft cabin. The PCO was designed to be a modular unit, with four UV lamps sandwiched between two interchangeable titanium dioxide coated panels. Performances of the PCO unit has been measured in a single pass mode test rig in order to show the ability of the unit to decrease the amount of VOCs (toluene, ethanol, and acetone) entering it (VOCs are fed separately), and in a multipass mode test rig in order to measure the ability of the unit to clean the air of an experimental room polluted with the same VOCs (fed separately). Triangular cell panels have been chosen instead of the wire mesh panels because they have higher efficiency. The efficiency of the PCO unit depends on the type of VOCs that challenges it, toluene being the most difficult one to oxidise. The efficiency of the PCO unit decreases when the air flow rate increases. The multipass mode test results show that the VOCs are oxidized but additional testing time would be necessary in order to show if they can be fully oxidized. The intermediate reaction products are mainly acetaldehyde and formaldehyde whose amount depends on the challenge VOC. The intermediate reaction products are also oxidized and additional testing time would be necessary in order to show if they can be fully oxidized. The development of this new photocatalytic air filter is still going on. PRACTICAL IMPLICATIONS: The VOC/odor removing adsorbers are available for only a small proportion of aircraft currently in service. The photocatalytic oxidation (PCO) technique has appeared to be a promising solution to odors problems met in aircraft. This article reports the test results of a new photocatalytic oxidation air filter (PCO unit) designed for aircraft cabin applications. The overall efficiency of the PCO unit is function of the compound (toluene, ethanol, and acetone) that challenges the unit and toluene appears to be the most difficult compound to oxidize. Test results have shown the influence of the design of the PCO unit, the air flow rate and the type of UV on the efficiency of the PCO unit. The results obtained in this study represent a first attempt on the way to design a filter for VOC removal in cabin aircraft applications. The PCO technique used by the tested prototype unit is able to partially oxidized the challenge VOCs but one has to be aware that some harmful intermediate reaction products (mainly formaldehyde and acetaldehyde) are produced during the oxidation process before being partially oxidized too.

Air Pollution, Indoor↗
PubMed1999

Complete androgen insensitivity caused by a splice donor site mutation in intron 2 of the human androgen receptor gene resulting in an exon 2-lacking transcript with premature stop-codon and reduced expression.

Various mutations within the human androgen receptor gene have been documented to cause defective sexual differentiation in karyotypic male individuals. In this study, we report a previously undescribed point mutation at the donor splice-site of the second intron of the androgen receptor gene in a patient with a completely female phenotype. The sequence alteration was detected by single-strand-conformation-analysis-PCR and genomic sequencing. Applying competitive reverse transcribed PCR, cDNA sequencing and Western blotting, we could demonstrate considerable aberrations of structure and concentration of the transcript and its translation product in the patient's fibroblasts from the genital region. (1) In the transcript, exon 1 and 3 are directly linked to each other, the complete second exon is skipped. The mRNA predictively suffers a codon frame-shift in exon 3 associated with a premature termination between codons 598 and 599, leading to a truncated androgen receptor protein lacking any in vivo function. (2) Steady-state concentration levels of transcript and protein are abnormally low. Our observations highlight the influence of exon-flanking intron sequences on proper expression and function of gene products.

Amino Acid Sequence↗
PubMed1999

Regulation of CD97 protein in thyroid carcinoma.

CD97 is a dimeric glycoprotein belonging to the secretin receptor superfamily and is abundantly expressed in cells of hematopoietic origin. The aim of this study was to analyze the expression of the CD97 protein in thyroid carcinomas and the role of all-trans-retinoic acid (RA) in the regulation of CD97 protein in monolayer culture of the human follicular thyroid carcinoma cell line FTC-133. In normal thyroid tissue, no immunoreactivity of CD97 could be found, whereas in differentiated thyroid carcinomas, CD97 expression was either lacking or low. Undifferentiated anaplastic thyroid carcinomas revealed high CD97 expression. The expression of CD97 protein seems to be correlated to the postoperative histopathological classification staging. Approximately 50% of FTC-133 cells expressed the CD97 protein under basal culture conditions. No differences were found in the number of CD97-positive cells after TSH, forskolin, and insulin treatment compared to control values. Epidermal growth factor treatment led to an increase in CD97 immunostaining (up to 90%), whereas phorbol 12-myristate 13-acetate slightly decreased the immunoreactivity of CD97 (from 50% to 30%). Under basal conditions, RA treatment for 72 h led to a decrease in total cell number by 33% and in CD97-positive cells from 50% to 30%. TSH, forskolin, phorbol 12-myristate 13-acetate, and insulin showed no effect after 72-h pretreatment with RA, whereas epidermal growth factor treatment led to a slight increase in the number of the CD97-positive cells (from 30% to 40%) compared to the control value. These data suggest that CD97 expression may play an important role in the dedifferentiation of thyroid tumors, and RA might interfere with this process in thyroid carcinoma by suppressing the dedifferentiation marker CD97.

Adult↗
PubMed1997

Survival analysis in observational studies.

Multi-centre databases are making an increasing contribution to medical understanding. While the statistical handling of randomized experimental studies is well documented in the medical literature, the analysis of observational studies requires the addressing of additional important issues relating to the timing of entry to the study and the effect of potential explanatory variables not introduced until after that time. A series of analyses is illustrated on a small data set. The influence of single and multiple explanatory variables on the outcome after a fixed time interval and on survival time until a specific event are examined. The analysis of the effect on survival of factors that only come into play during follow-up is then considered. The aim of each analysis, the choice of data used, the essentials of the methodology, the interpretation of the results and the limitations and underlying assumptions are discussed. It is emphasized that, in contrast to randomized studies, the basis for selection and timing of interventions in observational studies is not precisely specified so that attribution of a survival effect to an intervention must be tentative. A glossary of terms is provided.

Algorithms↗
PubMed1996

An empirical comparison of expert-derived and data-derived classification trees.

Classification trees provide an attractively transparent discrimination technique, and may be derived from both expert opinion and from data analysis. We consider a real and complex problem concerning the diagnosis of babies with suspected critical congenital heart disease into one of 27 classes. A full loss matrix for all possible misclassifications was obtained from clinical assessments. A tree derived from expert opinion was compared with those derived from analysis of 571 past cases, both for the full problem and for a subset of 6 diseases. Automatic methods for tree creation and pruning were found to have problems for rare diseases, and hand-pruning was carried out. Inclusion of costs led to much improved clinical performance, even for trees that had originally been constructed to minimize classification errors. The expert tree showed a specific building strategy that could not be reproduced automatically. The expert tree generally outperformed those derived from data, particularly in the ability to identify important composite features.

Algorithms↗
PubMed1995

Presentation and attrition in complex pulmonary atresia.

OBJECTIVES: This study summarized patterns of presentation and attrition in complex pulmonary atresia. BACKGROUND: Assessment of the potential impact of surgical strategies for managing complex pulmonary atresia requires information about variability in age and physiology at presentation of the condition. METHODS: We performed a retrospective review of age at presentation, referral source, pulmonary artery and collateral anatomy and surgical history of 218 patients from two institutions dealing with congenital heart disease throughout life. RESULTS: Approximately 65% of pulmonary atresia appears in infancy, with 50% of patients severely symptomatic from cyanosis and 25% from heart failure. Compared with those presenting undiagnosed, patients referred secondarily for specialist management tend to be older when first seen, and care must be taken when generalizing about the natural history of the condition from their survival experience. Overall actuarial survival, including the effects of operation, suggests that 60% (95% confidence limits [CL] 43 to 73) of patients presenting in infancy survive to their first birthday, 65% (95% CL 51 to 74) of those alive at 1 year old survive to the age of 10, and 16% (95% CL 5 to 31) of those alive at 10 years old survive to age 35. CONCLUSIONS: Novel surgical approaches have generally been applied beyond infancy in patients selected by their survival through the period of greatest attrition for this disease. Unless successful application in symptomatic infants is demonstrated, we cannot assume that these serial and complicated operations will have a major impact on the outlook of most patients with complex pulmonary atresia.

Actuarial Analysis↗
PubMed1991

Evaluation of a diagnostic algorithm for heart disease in neonates.

OBJECTIVE: To develop, test, and validate an algorithm for diagnosing disease in neonates during an over the telephone referral to a specialist cardiac centre. DESIGN: A draft algorithm requiring only data available to a referring paediatrician was generated. This was modified in the light of a retrospective review of case records. A questionnaire to elicit all the data required by the algorithm was then generated. There followed a prospective three phase evaluation during consecutive over the telephone referrals. This consisted of (a) a conventional phase with unstructured referral consultations, (b) a phase with referrals structured around the questionnaire but independent of the algorithm, and (c) a validation phase with the algorithm (and its previous errors) available during the referral consultation. SETTING: 59 paediatric centres in south east England and a central specialist paediatric cardiology unit. PATIENTS: Consecutive neonates (aged less than 31 days) referred with suspected heart disease. The retrospective review was of records of 174 neonates from 1979. In the prospective evaluation (1987-90) the conventional phase comprised 71 neonates (over 5.5 months), the structured phase 203 neonates (over 14 months), and the validation phase 195 neonates (over 12 months). MAIN OUTCOME MEASURES: Diagnostic accuracy (assigning patients to the correct diagnostic category (out of 27)), of the referring paediatrician, the specialist after the referral consultation, and the algorithm as compared with the definitive diagnosis by echocardiography at the specialist centre, and score for the appropriateness of management in transit. RESULTS: Simply structuring the consultation by questionnaire (that is, proceeding from the conventional phase to the structured phase) improved the diagnostic accuracy of both paediatricians (from 34% (24/71 cases) to 48% (97/203) correct) and specialists (from 54% (38/71 cases) to 64% (130/203) correct). The algorithm (structured phase) would have been even more accurate (78% (158/203 cases); p less than 0.01). Management scores in the structured phase were also better than in the conventional phase (80%(162/203 cases)v 58% (41/71) appropriate; p less than 0.01). Management scores would have improved to 91% appropriate (185/203; p less than 0.001) had the algorithmic diagnoses dictated management. The superiority of the algorithm was maintained but not bettered in the validation phase. CONCLUSIONS: Applying the algorithm should reduce the morbidity and mortality of neonates with critical heart disease by aiding clinicians in therapeutic decisions for in transit care.

Algorithms↗
PubMed1989

Combining clinical judgement and statistical data in expert systems: over-the-telephone management decisions for critical congenital heart disease in the first month of life.

When a new-born baby with congenital heart disease is referred to a regional specialist centre, the transportation management is crucial but must be decided on the basis of clinical information obtained over the telephone. We consider algorithmic and naive statistical approaches to helping in this decision, and on the basis of preliminary results the relative strengths and weaknesses are discussed. A synthesised logical and probabilistic approach appears to have the best potential and could be implemented on hand-held computers.

Algorithms↗
PubMed1989

[Hemorheologic findings in patients with ischemic heart disease].

The paper deals with the rheological properties of the blood of 38 male patients affected by ischaemic heart diseases (age: 40-75 years) and 19 healthy test persons of comparable age. The following haemorheological properties were measured. 1. Relative plasma viscosity 2. Erythrocyte aggregation 3. Erythrocyte deformability 4. Thrombocyte aggregation and 5. Whole blood viscosity. For the purpose of representing and assessing the results of measurement obtained a division was made into different groups according to the appearances of ischaemic heart disease (chronic ischaemic heart disease, unstable angina pectoris, acute heart infarct) and risk factors (smoking, diabetes mellitus, blood high pressure and hyperlipidaemia). The methods 1-3 proved to be especially suitable for representing gradual differences in the examined rheological parameters. The results obtained are discussed and evaluated.

Adult↗
PubMed1986

Antibody response to anaerobic coccoid rods in Crohn's disease.

The IgG and IgM specific antibodies against a panel of 23 anaerobic gut bacteria were examined in Crohn's disease, ulcerative colitis, and healthy controls. Four of the organisms, Bifidobacterium bifidum, Coprococcus comes (ME46), Coprococcus comes (Sp4), and Eubacterium limosum gave abnormal antibody titres in Crohn's disease compared with those of controls. In Crohn's disease specific IgG antibodies to three of the organisms were low and the IgM antibodies were higher than those of controls. IgM antibodies were also raised in ulcerative colitis. Antigenic cross reactivity could be shown between some of these organisms. The possible clinical importance of these abnormal antibody responses to specific organisms is unexplained.

Bacteria, Anaerobic↗