Biomedical subjects
Publications and source records attributed to T N Bryant.
This article outlines the mistakes that are commonly made when data are presented graphically. Common errors when displaying data are highlighted, and preferred solutions for avoiding these mistakes are described. The preferred approaches form the requirements that authors should meet when submitting papers to the journal of Pediatric Allergy and Immunology.
To ascertain the outcome of childhood vesicoureteric reflux (VUR), 226 adults (37 males), mean age 27 years, were studied after 10-35 years, extended to 41 years by postal questionnaire in 161. At presentation (mean age 5 years) all had VUR (grade III-V in 68) and urinary tract infection (UTI); there was renal scarring in 85 (acquired before referral in 11 and during follow-up in 1), hypertension in 6 and impaired renal function in 5. They were managed and followed prospectively by one paediatrician; 63% of these children remained free from UTI; VUR persisted in 63 and had resolved in 69% of 193 children managed medically. At follow-up, 61% of adults had remained free from infection; 17 adults had hypertension and/or raised plasma creatinine, 16 with scarred kidneys. Their deterioration was predictable because of scar type, blood pressure or plasma creatinine levels in childhood. No new scars developed after puberty. Renal growth rates were unaffected by initial severity or persistence of VUR. On the later questionnaire, 9 further adults, mean age 38 years, had moderate hypertension. The adults with complications were those with extensive renal scarring and/or at least borderline hypertension in childhood. Those with VUR, but no scarring, and managed carefully in childhood, did not suffer serious consequences as adults. There is a need for early recognition and treatment of children with VUR and UTI to limit scar development.
This article outlines the statistical requirements that authors should fulfill when submitting manuscripts to Pediatric Allergy and Immunology. The requirements are based on the 'Uniform Requirements for Manuscripts Submitted to Biomedical Journals' and the CONSORT statement. Common statistical flaws that routinely arise in the medical literature are described. The use of +/-, confidence intervals and P values, correlation and regression, multiple testing and repeated measures are discussed.
OBJECTIVES: To describe the effect of occult invasive disease on progress towards meeting the Health of the Nation target for reducing the incidence of cervical cancer, and to investigate the possible effect of a higher risk of cervical cancer in women born since 1940. SETTING: Southampton and South West Hampshire (SSWH), with a total female population of 218,549 in 1990, the midpoint of a study period covering 1985 to 1995. METHODS: Incidence was calculated per 100,000 women years at risk in overlapping three year periods for symptomatic and screen detected cancers. The same methods was used for cohorts of women born before and after 1940. Screen detected stage Ia1 cancers were identified as a subgroup. RESULTS: The incidence of invasive cervical cancer fell by 27.4%, from 16.8 to 12.2 per 100,000 women years at risk between 1985-87 and 1993-95, which was a significant linear trend (chi 2 = 4.494, df = 1, p = 0.034). The corresponding figures adjusted for age in a standardised European population were 16.3 and 11.5: a fall greater than required to meet the Health of the Nation target set for the year 2000. Incidence remained relatively high until screen detected cancers, more than one third of which were stage Ia1, had passed a peak in 1992. When screen detected stage Ia1 cancers were excluded, incidence fell by 41.2%, from 16.5 to 9.7 per 100,000 women years at risk: a highly significant linear trend (chi 2 = 12.391, df = 1, p < 0.001). The incidence in the first three years of the study was higher in women born between 1940 and 1954 than in those born between 1925 and 1939, though the reverse would be expected by age and the natural history of the disease. In the 1940-54 birth cohort 44% (23/52) of screen detected cancers were stage Ia1, with a peak in 1992. When these were excluded, incidence fell by 57.1%, from 31.7 to 13.6 per 100,000 women years at risk: a highly significant linear trend (chi 2 = 13.704, df = 1, p < 0.001), whereas an increase would be expected for a cohort aged from 30-45 to 40-55. In the 1925-39 cohort only 24% (8/33) of screen detected cancers were stage Ia1. When these were excluded, incidence fell by 35.3%, from 24.9 to 16.1, which was not a significant linear trend (chi 2 = 0.409, df = 1, p = 0.522). CONCLUSION: An overall decline in incidence was not achieved until prevalent occult invasive disease had been detected by improved screening. The data confirm the effectiveness of screening, particularly in a high risk cohort of women born between 1940 and 1954.
Blood samples were obtained from fetuses and premature babies (n = 51) (15-34 weeks gestation) to determine at what stage the fetal immune system was able to produce a positive proliferative response to common allergens. Peripheral blood mononuclear cells (PBMC) were stimulated with the mitogen, phytohaemagglutinin (PHA), and the allergens, house dust mite, cat fur, birch tree pollen, beta-lactoglobulin, ovalbumin and bee venom (mellitin). Results were expressed as ratios of stimulated to unstimulated 3H thymidine incorporation, and as percent positive responders. There was an increase in proliferation ratio which correlated with increasing gestational age for PHA (p < 0.0001), cat fur (p = 0.042), birch pollen (p = 0.022) and beta-lactoglobulin (p = 0.006). The point in gestation when cells from some individuals began responding to the allergens with a ratio of 2.0 was at approximately 22 weeks. PBMC proliferative response ratios were higher from samples from babies > 22 weeks gestation compared to < 22 weeks for the mitogen and all allergens, except mellitin. There was also a greater proportion of positive responders from samples > 22 weeks compared to < 22 weeks for the mitogen and all allergens, except mellitin. Maternal exposure to birch pollen, which has a discrete season, was assessed to determine whether exposure had occurred at 22 weeks gestation or beyond. Results showed a higher proliferative response in infant cells stimulated with birch pollen (p = 0.005) and higher proportion of positive responders (p = 0.01) in the group of babies whose mothers had been exposed to birch pollen beyond 22 weeks, compared to those whose mothers had not been so exposed. These results suggest that in utero fetal exposure to an allergen from around 22 weeks gestation may result in primary sensitisation to that allergen, leading to positive proliferative responses, at birth.
A study of invasive cervical cancer in Southampton and South West Hampshire is reported, covering three consecutive three year periods during which the screening coverage increased from an estimated 60% to a recorded 87% of eligible women aged 20-64. From the first to the third periods of the study in that age group registrations of fully invasive squamous cell carcinoma (stage lb and above) fell from 64 to 30 (53%), which was largely counteracted by an increase in microinvasive squamous cell carcinoma (linear trend: P<0.0001). In the same age group registrations of adenocarcinoma rose slightly, which resulted from an increase in the number diagnosed at a depth of invasion of less than 3 mm. There were no significant changes in the numbers of stage III and IV cancers or among cancers in women aged 65 and over. A strong inverse association was found between stage of both histological types of cancer and their likelihood of being screen detected rather than symptomatic: 91% of screen detected cancers were diagnosed at stage I compared with 38% of symptomatic cancers. There was a slight downward trend in the incidence of cancer per 100,000 total female population across the three periods of the study with a significant trend towards low stage disease, which is likely to reduce mortality in years to come. The trend towards screen detected cancers and cancers of less than 3 mm depth of invasion is presented as a positive outcome to be expected in early rounds of increasing the screening coverage.
OBJECTIVE: To examine the incidence of invasive cervical cancer per 100,000 women years at risk and relative risk according to screening history among eligible women aged 25-69 in Southampton and South West Hampshire during the three years after completion of the first round of comprehensive screening. RESULTS: There was a significantly higher incidence of invasive cervical cancer in women who had not been screened during the preceding 0.5-5.5 years than in those who had been screened (relative risk (RR) 2.6; 95% confidence interval (CI) 1.6 to 4.3). Among the latter group of women (with interval cancers) there was a significantly higher incidence in those with a long interval of 3.5-5.5 years since their most recent smear than in those with a short interval of 0.5-3.5 years (RR 2.2; 95% CI 1.3 to 3.8). Among women with non-interval cancers, there was a significantly higher incidence among those who had no cytology record than among those who had been screened but were overdue for a smear (RR 3.0; 95% CI 1.2 to 7.3). When screen detected cancers were excluded from the figures the relative risks for all the comparative groups described above were greater, though the 95% confidence limits were wider because the numbers were smaller. The most pronounced difference in incidence was between symptomatic cancers in women with a short screening interval (5.8 per 100,000 women years at risk) and in women with no cytology record (71.3 per 100,000 years at risk). Most cancers were interval cancers (76%) because of the high screening coverage: 89.2% of eligible women aged 25-69 had been screened during the preceding 0.5-5.5 years. The overall incidence per 100000 women years at risk approached that of interval cancers, and was nearer to that observed in the short than the long interval because 74.7% of women had been screened within 3.5 years. CONCLUSION: The results confirm the effectiveness of screening but suggest that a five year screening interval may be too long, at least during the early rounds of screening.
BACKGROUND: Raised peripheral blood mononuclear cells (PBMCs) proliferative responses to food allergens have been demonstrated in children with established atopic dermatitis. OBJECTIVE: In this report we investigate the PBMC proliferative responses to inhalant and food allergens from babies at birth, 6 months and 1 year of age, born to atopic and non-atopic parents. METHODS: PBMCs, separated by density gradient centrifugation, were cultured for 6 days with autologous plasma and a range of allergens (house dust mite [HDM], cat, grass pollen, tree pollen, betalactoglobulin and ovalbumin). Proliferative responses were measured by the uptake of [3H] thymidine added for the final 18 h of culture. RESULTS: At birth, infants born to atopic parents who developed allergic disease by 1 year of age had significantly more positive responses (stimulation index > or = 2 with a value of > or = 1000 cpm above background) to HDM (P = 0.0097), betalactoglobulin (P = 0.0166) and ovalbumin (P = 0.0035) than newborns who did not develop allergy. Infants who developed allergy also had significantly more positive responses to HDM (P = 0.03) and ovalbumin (P = 0.0057) than babies, born to non-atopic parents, who did not develop allergies. At 6 months of age a significant fall in response to HDM (P = 0.003) and cat fur extract (P = 0.006) was seen in infants who developed allergic disease by 1 year of age. A similar pattern was seen for proliferative responses to betalactoglobulin and ovalbumin (P = 0.0006, P = 0.004). Conversely, proliferations to grass and tree pollen extracts increased at 6 months (P = 0.04, P = NS) and 1 year (P = NS, P = 0.01) compared with birth which was significant for infants who did not develop allergic disease. CONCLUSION: Proliferative responses to seasonal allergens increased over the first year of life whilst those to perennial allergens, both inhalant and food, fell. This suggests either the induction of a systemic immune tolerance by perennial exposure to antigens or movement of sensitized cells to target organs where allergen exposure occurs. This process may be independent of the development allergic disease.
Bacterial Identification, first described by Bryant (1986), is a program that provides a novel way of enhancing the teaching of systematic bacteriology and numerical identification procedures. A student is assigned an unknown isolate from a list of bacteria. The student's objective is to identify the unknown isolate using the least number of tests from the set of tests available. Simultaneously the computer tries to identify the unknown using optimised and random selection of tests. A student can compare their progress against that of the computer. The program has been improved and the data matrix on which it was based has been revised by the addition of 14 more species, an additional test and by updating the original probability matrix. The program, Bacterial Identification, is available as 'freeware' and has been placed with organisations that distribute such software.
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A program has been written to help identify the correct RKC codes (Rogosa, Krichevsky and Colwell, 1986) for describing microbiological attributes. Terms, which may be complete words, parts of words, or numbers, can be typed into the computer. A search is made of the set of about 13,800 RKC codes and statements that describe them. Statements that contain the search terms are displayed in a scrolling window so that the required statement(s) can be identified. A list of selected RKC statements can be built up in a second window for subsequent use by other software packages. The program called RKCLIST runs under the MS-DOS operating system. The software routines used to create RKCLIST have been written so that they can be incorporated into other software packages that make use of the RKC coding scheme.
Keyboard entry of large amounts of diagnostic data is a laborious task. Any transcription errors that occur may pass undetected by 'non-technical staff' employed to input these data. The object of this project was to design a system, based on a Marconi 'Macrospeak' Speech Recogniser, for 'on line' laboratory entry of data generated from the microbiological examination of specimens of urine. Six parameters considered important to the success of the system were assessed: accuracy, speech recognition, reproducibility, speed, user friendliness, and cost effectiveness. The system performed well under the test conditions examined. 'On line' hands free entry of diagnostic data, using speech recognition, may be a practical alternative to more conventional means of data entry.
A number of programs are described for the development and evaluation of probabilistic identification matrices for use with computer-assisted identification. The program BEST reads an initial matrix of per cent probabilities for all the binary characters examined during a cluster analysis and determines the most useful set of tests for distinguishing taxa in the matrix. Program RESORT creates from the initial matrix an identification matrix in which the order of the tests may be different or the number of tests reduced. A printed version of a matrix can be produced by MATPRINT, which creates tables giving the per cent probability of a positive test result and the test results presented as '-', 'v' and '+' depending on a user-specified threshold. Program IDSC evaluates an identification matrix by calculating the best identification score for each taxon in the matrix using the expected result for each test. The programs were written in FORTRAN 77 and can be run on any micro-computer using the PC/MS-DOS operating system.
An investigation was carried out to assess the feasibility of using an expert systems approach to assist in the identification of unknown isolates of bacteria. A system was developed using Lisp which utilized the knowledge stored in standard bacteriological texts. A comparison of the expert systems approach and the probabilistic approach based on Bayes Theorem was made together with the advantages and disadvantages of each approach.
Sixty-one isolates of Aeromonas spp. from the faeces of pigs, cows and a variety of associated environmental sources were examined for the characteristics that are reputed to have roles in pathogenicity. Most isolates of Aeromonas hydrophila were cytotoxic (96.4%) and were capable of producing cell elongation factor (75%) and haemagglutinins (67.9%). In contrast few of the Aeromonas caviae isolates produced these three markers (13.6%, 27.3% and 36.4% respectively). In general, Aeromonas sobria occupied an intermediate position (36.4%, 27.3% and 54.5%), but they did produce the highest mean invasion index for HEp-2 cells. Statistical analysis revealed significant associations between the carriage of these factors and it was clear that many isolates of aeromonads from water and animals possessed the full battery of putative virulence factors.
A randomised study of 381 women was carried out to compare the obstetric outcome after epidural analgesia maintained by an intermittent top-up regimen or with a continuous infusion. The two groups were well matched with respect to age, parity, mode of onset of labour and indication for epidural. Maintenance of epidural analgesia by continuous infusion resulted in a significantly decreased need for top-up doses. A reduction in the incidence of hypotension, cardiotocographic evidence of intrapartum fetal hypoxia and Caesarean section was associated with this. It is concluded that the maintenance of epidural analgesia by continuous infusion is a safe and reliable method and may be more advantageous and less labour intensive than the traditional intermittent regimen.
A panel of 19 monoclonal antibodies was used to produce patterns of immunofluorescent staining of 468 isolates of Legionella pneumophila. Twelve monoclonal antibodies were selected that divided L. pneumophila into 17 phenons which, in the majority of cases, conform to serogroup divisions. These phenons are more easily defined than the present serogroups, and isolates can be placed in them with little ambiguity. The standardized set of monoclonal antibodies was also used to define the subgroups of serogroup 1.
Urine samples from neonates admitted to a special care baby unit were analysed to establish ranges for urinary retinol binding protein, albumin, and total protein concentrations in healthy term and preterm infants and to investigate changes seen in disease states. Urinary excretion of retinol binding protein was greater in preterm infants and was increased in sick infants. This was greater than would be predicted from changes in creatinine excretion with gestational or postconceptional age. Urinary retinol binding protein appeared more sensitive to illness than did urinary albumin or total protein.