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Biomedical subjects

A M Johnson

Publications and source records attributed to A M Johnson.

At least 37 records · Page 2Linked to original sources

Lupus headaches in childhood-onset systemic lupus erythematosus: relationship to disease activity as measured by the systemic lupus erythematosus disease activity index (SLEDAI) and disease damage.

The Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) is the most commonly used measure of disease activity for children with systemic lupus erythematosus (SLE). For headaches to be scored in the SLEDAI as a symptom of active disease, they have to be nonresponsive to narcotic analgesia. This may affect the overall estimation of disease activity, especially because headaches are common among children with SLE and narcotic analgesia is rarely used for headache therapy in paediatrics. Moreover, the importance of headaches for the development of damage and their relation to other clinical parameters and outcomes has not been well described for children with SLE. We reviewed the medical charts of an inception cohort of children (n = 63) who were newly diagnosed with SLE. Information on headaches and other disease parameters was obtained. Disease activity and damage were measured using the SLEDAI and the Systemic Lupus International Collaboration Clinics/American College of Rheumatology Damage Index (SDI), respectively. It has been shown that the accumulated burden of active disease as measured by serial SLEDAI scores over time is one of the best predictors of eventual damage to children with SLE. New-onset or significant increase of severe and/or persistent headaches (LHA) were reported in 43% of the patients during a mean follow-up of 3.6 years. LHA occurred preferentially among patients with elevated levels of antiphospholipid antibodies (aPL) (P < 0.02) and only 6% of all LHA episodes were treated with narcotics and thus considered for the measurement of disease activity in the SLEDAI. LHA were unrelated to proxy-measures of disease activity, such as the need to intensify therapies. When used in children, the insensitivity of the SLEDAI to capture LHA did not seem to decrease the responsiveness of the SLEDAI to detect clinically important worsening of disease, or negatively impact on its ability to predict damage.

Adolescent↗

Myosins of Babesia bovis: molecular characterisation, erythrocyte invasion, and phylogeny.

Using degenerate primers, three putative myosin sequences were amplified from Australian isolates of Babesa bovis and confirmed as myosins (termed Bbmyo-A, Bbmyo-B, and Bbmyo-C) from in vitro cultures of the W strain of B. bovis. Comprehensive analysis of 15 apicomplexan myosins suggests that members of Class XIV be defined as those with greater than 35% myosin head sequence identity and that these be further subclassed into groups bearing above 50-60% identity. Bbmyo-A protein bears a strong similarity with other apicomplexan myosin-A type proteins (subclass XIVa), the Bbmyo-B myosin head protein sequence exhibits low identity (35-39%) with all members of Class XIV, and 5'-sequence of Bbmyo-C shows strong identity (60%) with P. falciparum myosin-C protein. Domain analysis revealed five divergent IQ domains within the neck of Pfmyo-C, and a myosin-N terminal domain as well as a classical IQ sequence unusually located within the head converter domain of Bbmyo-B. A cross-reacting antibody directed against P. falciparum myosin-A (Pfmyo-A) revealed a zone of approximately 85 kDa in immunoblots prepared with B. bovis total protein, and immunofluorescence inferred stage-specific myosin-A expression since only 25% of infected erythrocytes with mostly paired B. bovis were immuno-positive. Multiplication of B. bovis in in vitro culture was inhibited by myosin- and actin-binding drugs at concentrations lower than those that inhibit P. falciparum. This study identifies and classifies three myosin genes and an actin gene in B. bovis, and provides the first evidence for the participation of an actomyosin-based motor in erythrocyte invasion in this species of apicomplexan parasite.

Actins↗

The accuracy of reported sensitive sexual behaviour in Britain: exploring the extent of change 1990-2000.

OBJECTIVES: The 1990-1 British national probability sample survey of sexual attitudes and lifestyles (Natsal 1990) was repeated in 1999-2001 (Natsal 2000) to update population estimates of risk behaviours, and assess change over time. We examine whether changes in prevalence estimates may partly result from changes in measurement accuracy. METHODS: Taking Natsal 2000 (11 161 respondents) and Natsal 1990 (13 765 respondents aged 16-44) we compared the response rate, sample representativeness, reporting of abortion last year (relative to official statistics), and selected attitudes. Among the common birth cohort eligible for both surveys (aged 16-34 Natsal 1990, 26-44 Natsal 2000), we compared reporting of experiences before 1990. RESULTS: The response rate (66.8% Natsal 1990, 65.4% Natsal 2000) and completeness of reporting abortion were unchanged (84% Natsal 1990, 86% Natsal 2000). Attitudes were significantly changed in Natsal 2000 relative to Natsal 1990--for example, increased tolerance of male homosexual sex, OR (95% CI) 2.10 (1.93-2.29) men and 2.95 (2.74 to 3.18) women. In the common birth cohort reporting of heterosexual intercourse before 16 (OR 1.15 (1.02 to 1.29) men, 1.49 (1.31 to 1.69) women), and homosexual experience (OR 1.80 (1.46 to 2.21) men, 2.00 (1.61 to 2.48) women) were significantly increased. CONCLUSIONS: The results are consistent with improved reporting accuracy for some sensitive behaviours in Natsal 2000, in line with greater social tolerance and improved survey methodology. However, the evidence is not conclusive, and may not be generalisable to all such behaviours. The increase found in the reported prevalence of STI risk behaviours between Natsal 1990 and Natsal 2000 is likely to be somewhat overstated.

Adolescent↗

Herpes simplex virus type 1 infection: a sexually transmitted infection of adolescence?

OBJECTIVES: To examine the factors associated with antibodies to herpes simplex virus type 1 (HSV-1). DESIGN: Cross sectional study with HSV-1 antibody testing performed by University of Washington western blot assay. SETTING: Central London STD clinic (1990-1) and central London blood donation centre (1992). PARTICIPANTS: Representative sample of 869 new and rebooked GUM clinic attenders and 1494 consecutive blood donors. RESULTS: The prevalence of HSV-1 antibody among clinic attenders was 60.4% (95% CI 57.0 to 63.7) and among donors was 46.1% (95% CI 43.5 to 48.7). HSV-1 antibody was independently associated with increasing age in both populations (p<0.001). Among clinic attenders, HSV-1 was less common among heterosexual men than women and homosexual men (p<0.005), and was more common among black people (p=0.001) and those of lower socioeconomic status (p=0.05). Among blood donors, being single rather than married was independently associated with HSV-1 infection (p=0.03). Early age at first intercourse was strongly associated with presence of HSV-1 in both populations. The adjusted odds of HSV-1 among GUM clinic attenders was 0.37 (95% CI 0.21 to 0.65) for someone aged 20 at first intercourse compared with someone aged <or=15. Among blood donors, those aged 20 had an adjusted odds of 0.64 (95% CI 0.39 to 1.05) compared with someone aged 15. HSV-1 was not associated with increasing number of lifetime partners after adjustment for other factors. CONCLUSIONS: Genital herpes due to HSV-1 antibody is increasing in the United Kingdom, particularly among young people. In this study we found that HSV-1 was strongly associated with early age of first sexual intercourse, which may reflect the sexual practices of people initiating sex in this age group.

Adolescent↗

Phase specific strategies for the prevention, control, and elimination of sexually transmitted diseases: background country profile, England and Wales.

The development of non-invasive tests for evidence of current or past infection offers new prospects for carrying out population studies of sexually transmitted infection (STI) epidemiology, and for improved understanding of the behavioural and biological determinants of STI transmission. In turn this may guide screening, treatment, and behavioural interventions. The evidence base for many interventions is sparse and randomised trials of interventions are in their early days. Increasingly, linked behavioural and biological outcomes will be required to measure effectiveness. Integrated efforts are needed at a national level to achieve greater coordination between STD, HIV, and contraception services, school education, and broader public education and programmes.

Adolescent↗

Response to antiretroviral therapy among patients exposed to three classes of antiretrovirals: results from the EuroSIDA study.

There is an increasing proportion of HIV-positive patients exposed to all licensed classes of antiretrovirals, and the response to salvage regimens may be poor. Among over 8500 patients in EuroSIDA, the proportion of treated patients exposed to nucleosides, protease inhibitors (PIs) and non-nucleoside reverse transcriptase inhibitor (NNRTI) increased from 0% in 1996 to 47% in 2001. Four-hundred-and-thirteen patients, who had failed virologically two highly active antiretroviral therapy (HAART) regimens and experienced all three main drug classes, started a salvage regimen of at least three drugs, in which at least one new PI or NNRTI was included. Median viral load was 4.7 log copies/ml [Interquartile range (IQR) 4.2-5.2], CD4 lymphocyte count 150/mm3 (IQR 60-274/mm3) and follow-up 14 months. Of these patients, 283 (69%) subsequently experienced at least a 1 log decline in viral load and 202 (49%) achieved a viral load < 500 copies/ml. Conversely, the CD4 count halved from the baseline value in 88 (21%), and 45 (11%) experienced a new AIDS-defining disease. In multivariable analyses, a 1 log viral load reduction was related to baseline viral load [relative hazard (RH) 1.27 per 1 log higher; P = 0.008], a previous viral load of less than 500 copies/ml (RH 1.69; P = 0.002), more recent initiation of the regimen (RH 1.36 per year more recent; P = 0.02), number of new drugs in the regimen (RH 1.20 per drug; P = 0.02), time since start of antiretroviral therapy (RH 0.94 per extra year; P = 0.035) and time spent on HAART with viral load > 1000 copies/ml (RH 0.96 per extra month; P = 0.0001). Analysis of factors associated with CD4 count decline and new AIDS disease also indicated improved outcomes in more recent times and a tendency for a better response in those starting more new drugs, but no relationship with the total number of drugs. Outcomes in people starting salvage regimens appear to depend on the number of new drugs started but not on the total number of drugs being used.

Acquired Immunodeficiency Syndrome↗

Sexual behaviour in Britain: partnerships, practices, and HIV risk behaviours.

BACKGROUND: Sexual behaviour is a major determinant of sexual and reproductive health. We did a National Survey of Sexual Attitudes and Lifestyles (Natsal 2000) in 1999-2001 to provide population estimates of behaviour patterns and to compare them with estimates from 1990-91 (Natsal 1990). METHODS: We did a probability sample survey of men and women aged 16-44 years who were resident in Britain, using computer-assisted interviews. Results were compared with data from respondents in Natsal 1990. FINDINGS: We interviewed 11161 respondents (4762 men, 6399 women). Patterns of heterosexual and homosexual partnership varied substantially by age, residence in Greater London, and marital status. In the past 5 years, mean numbers of heterosexual partners were 3.8 (SD 8.2) for men, and 2.4 (SD 4.6) for women; 2.6% (95% CI 2.2-3.1) of both men and women reported homosexual partnerships; and 4.3% (95% CI 3.7-5.0) of men reported paying for sex. In the past year, mean number of new partners varied from 2.04 (SD 8.4) for single men aged 25-34 years to 0.05 (SD 0.3) for married women aged 35-44 years. Prevalence of many reported behaviours had risen compared with data from Natsal 1990. Benefits of greater condom use were offset by increases in reported partners. Changes between surveys were generally greater for women than men and for respondents outside London. INTERPRETATION: Our study provides updated estimates of sexual behaviour patterns. The increased reporting of risky sexual behaviours is consistent with changing cohabitation patterns and rising incidence of sexually transmitted infections. Observed differences between Natsal 1990 and Natsal 2000 are likely to result from a combination of true change and greater willingness to report sensitive behaviours in Natsal 2000 due to improved survey methodology and more tolerant social attitudes.

Adolescent↗

Sexual behaviour in Britain: early heterosexual experience.

BACKGROUND: Relatively high rates of teenage conception and sexually transmitted infection among young people in Britain have focused attention on early sexual behaviour and its determinants. We report the results of the second National Survey of Sexual Attitudes and Lifestyles (Natsal 2000). METHODS: We did a probability sample survey between 1999 and 2001, of men and women aged 16-44 years in Britain. Participants were interviewed using a combination of computer-assisted face-to-face and self-completion questionnaires, and asked questions regarding first heterosexual intercourse, communication about sex, pregnancy, and sexually transmitted infections (STIs). FINDINGS: We recruited 11161 men and women to the survey (4762 men, 6399 women). The proportion of those aged 16-19 years at interview reporting first heterosexual intercourse at younger than 16 years was 30% for men and 26% for women; median age was 16 years. The proportion of women reporting first intercourse before 16 years increased up to, but not after, the mid-1990s. There has been a sustained increase in condom use and a decline in the proportion of men and women reporting no contraceptive use at first intercourse with decreasing age at interview. Among 16-24 year olds, non-use of contraception increased with declining age at first intercourse; reported by 18% of men and 22% of women aged 13-14 years at occurrence. Early age at first intercourse was significantly associated with pregnancy under 18 years, but not with occurrence of STIs. Low educational attainment was associated with motherhood before 18 years, but not abortion. INTERPRETATION: The increase in the proportion of women reporting first intercourse before age 16 years does not appear to have continued throughout the past decade. Only a small minority of teenagers have unprotected first intercourse, and early motherhood is more strongly associated with educational level than with family background. Factors most strongly associated with risk behaviour and adverse outcomes have considerable potential for preventive intervention.

Adolescent↗

Sexual behaviour in Britain: reported sexually transmitted infections and prevalent genital Chlamydia trachomatis infection.

BACKGROUND: Studies of the epidemiology of sexually transmitted infections (STI) are largely based on surveillance data. As part of a national survey of sexual attitudes and lifestyles (Natsal 2000) in Britain, we estimated the frequency of self-reported STIs, and the prevalence of urinary Chlamydia trachomatis infection. METHODS: We did a stratified probability sample survey of 11161 men and women aged 16-44 years in Britain. Computer assisted self-interviews contained items on the nature and timing of previously diagnosed STIs. Half of all sexually experienced respondents aged 18-44 years were invited to provide a urine sample for ligase chain reaction testing for C trachomatis infection. FINDINGS: 10.8% of men and 12.6% of women reported ever having an STI, 3.6% of men and 4.1% of women reported ever being diagnosed with genital warts, and 1.4% of men and 3.1% of women reported previous infection with C trachomatis. 76% of men and 57% of women ever diagnosed with an STI had been to a GUM clinic. C trachomatis was found in 2.2% (95% CI 1.5-3.2) of men and 1.5% (95% CI 1.11-2.14) of women with age-specific prevalence being highest among men aged 25-34 (3.1%) and women aged 16-24 years (3.0%). Non-married status, age, and reporting partner concurrency or two or more sexual partners in the past year were independently associated with infection with C trachomatis. INTERPRETATION: We show substantial heterogeneity in distribution of reported STIs, and the demographic and behavioural determinants of prevalent genital chlamydial infection. The results have potentially wide application for proposed chlamydia screening programmes which, given the demonstrated prevalence, must now proactively seek to involve men.

Adolescent↗

A cognitive behavioural intervention to reduce sexually transmitted infections among gay men: randomised trial.

OBJECTIVE: To determine the effectiveness of a brief cognitive behavioural intervention in reducing the incidence of sexually transmitted infections among gay men. DESIGN: Randomised controlled trial with 12 months' follow up. SETTING: Sexual health clinic in London. PARTICIPANTS: 343 gay men with an acute sexually transmitted infection or who reported having had unprotected anal intercourse in the past year. MAIN OUTCOME MEASURES: Number of new sexually transmitted infections diagnosed during follow up and self reported incidence of unprotected anal intercourse. RESULTS: 72% (361/499) of men invited to enter the study did so. 90% (308/343) of participants returned at least one follow up questionnaire or re-attended the clinic and requested a check up for sexually transmitted infections during follow up. At baseline, 37% (63/172) of the intervention group and 30% (50/166) of the control group reported having had unprotected anal intercourse in the past month. At 12 months, the proportions were 27% (31/114) and 32% ( 39/124) respectively (P=0.56). However, 31% (38/123) of the intervention group and 21% (35/168) of controls had had at least one new infection diagnosed at the clinic (adjusted odds ratio 1.66, 95% confidence interval 1.00 to 2.74). Considering only men who requested a check up for sexually transmitted infections, the proportion diagnosed with a new infection was 58% (53/91) for men in the intervention group and 43% (35/81) for men in the control group (adjusted odds ratio 1.84, 0.99 to 3.40). Using a regional database that includes information from 23 sexual health clinics in London, we determined that few participants had attended other sexual health clinics. CONCLUSIONS: This behavioural intervention was acceptable and feasible to deliver, but it did not reduce the risk of acquiring a new sexually transmitted infection among these gay men at high risk. Even carefully designed interventions should not be assumed to bring benefit. It is important to evaluate their effects in randomised trials with objective clinical end points.

Adolescent↗

Effect of computer-assisted self-interviews on reporting of sexual HIV risk behaviours in a general population sample: a methodological experiment.

OBJECTIVES: To develop methods to maximize the accuracy of reporting HIV risk behaviours in a general population survey. We assessed the feasibility of using a computer-assisted self-completion interview (CASI) in comparison with pen-and-paper self-completion interview (PAPI). DESIGN: A probability sample survey of residents aged 16-44 years in Britain, with alternate assignment of addresses to interview by CASI (462) or PAPI (439). METHODS: Personal interviews exploring demographic and sexual behaviour variables. Principal outcome measures were the impact of CASI in relation to PAPI on data quality and rates of reporting a range of behaviours. RESULTS: A total of 901 interviews were completed; 829 individuals were eligible for and accepted the self-completion module. Internal consistency of data items was greater with CASI than PAPI and item non-response was lower. Overall, there was no significant difference in rates of reporting between CASI and PAPI. The main effect for CASI compared with PAPI in a generalized estimating equation (GEE) analysis was an OR (95% CI) of 1.04 (0.92-1.17). Variables were also examined individually, including homosexual partnership (adjusted OR 1.26 95%, CI 0.69-2.29), payment for sex (adjusted OR 0.68 95% CI 0.29-1.59), masturbation (adjusted OR 0.89 95% CI 0.66 1.22) and five or more partners in the past 5 years (OR 0.85 95% CI 0.61 -1.19). CONCLUSION: We found no evidence of a consistent effect of CASI on rates of reporting sexual HIV risk behaviours in this sample. CASI resulted in improvement in internal consistency and a reduction in missed questions.

Adolescent↗

Weight-related body image concerns among 18-24-year-old women in Canada and India: an empirical comparative study.

OBJECTIVE: Sociocultural factors are important in the pathogenesis of eating disorders. We examined some core (DSM IV) features of eating disorders, i.e., drive for thinness and dissatisfaction with the weight of the abdomen, hips, and thighs among women in Canada and India. METHODS: A total of 65 Canadian (mean+/-S.D. age: 21.4+/-2.0 years) and 47 Indian (mean+/-S.D. age: 18.7+/-4.1 years) women completed the Drive for Thinness (DT) and Body Dissatisfaction (BD) subscales of the Eating Disorder Inventory (EDI) and in addition rated the degree to which they believed all major regions of their body were overweight. RESULTS: After the effects of body mass index (BMI) were partialled out statistically, the DT (EDI) and BD (EDI) scores were not significantly different between the two countries. In both groups, concerns about the weight of the abdomen, hips, thighs, and legs loaded on a factor that essentially described the 'body dissatisfaction' construct. After the effects of BMI were partialled out, however, the factor scores from this factor correlated with BD (EDI) in the Canadian but not the Indian sample. DISCUSSION: In contrast to the Canadian women, the Indian women did not overestimate the 'fatness' of their abdomen, hips, thighs, and legs. Among the Indian women, concerns about the weight of the upper torso (i.e., face, neck, shoulders, and chest) emerged as a distinct body image construct. In conclusion, after the effect of BMI was controlled for statistically, the Canadian and Indian women scored similarly on some of the core features of eating disorders, as measured by the DT (EDI) and BD (EDI) subscales, however, the nature of the underlying body image construct was different between the two groups.

Adipose Tissue↗

Von Hippel-Lindau disease masquerading as autosomal dominant polycystic kidney disease.

The diagnostic confusion in differentiating the various causes of renal cystic diseases in adults is well documented. This confusion can include misclassifications between autosomal dominant polycystic kidney disease (ADPKD) and von Hippel-Lindau disease (VHL). We describe such a case of VHL. A review of the literature and of the patients in our database regarding typical features of each disease, mean age of onset, and frequency of these features was undertaken to provide helpful differentiating features. Pancreatic cysts are one differentiating feature. In VHL, pancreatic cysts can occur in 70% of patients, often are multiple, and rarely may cause exocrine or endocrine insufficiency. Pancreatic islet cell tumors occur. In ADPKD, pancreatic cysts are found in only 9% of patients, usually are single and asymptomatic, generally occur in conjunction with cystic liver disease, and are not found in children or unaffected family members. Pancreatic malignancies do not occur with increased frequency in ADPKD. A different pattern, especially in patients without a strong family history of ADPKD, may be a clue to VHL masquerading as ADPKD. Genetic mutation screening of the VHL gene should be used in these patients.

Adult↗

Progression of autosomal-dominant polycystic kidney disease in children.

BACKGROUND: Although many case reports describe manifestations of autosomal-dominant polycystic kidney disease (ADPKD) in children, no longitudinal studies have examined the natural progression or risk factors for more rapid progression in a large number of children from ADPKD families. METHODS: Since 1985, we have studied 312 children from 131 families with a history, a physical examination, blood and urine chemistries, an abdominal ultrasonography, and gene linkage analysis. One hundred fifteen of 185 affected children were studied multiple times for up to 15 years. Renal volumes were determined by ultrasound imaging. Graphs of mean renal volumes according to age were compared between affected and unaffected children, ADPKD children with and without early severe disease, and children with and without high blood pressure. RESULTS: Affected children had faster renal growth than unaffected children. ADPKD children with severe renal enlargement at a young age continued to experience faster renal growth than those with mild enlargement or normal kidney size for their age, and affected children with high blood pressure had faster renal growth than those with lower blood pressure. Glomerular filtration rate did not decrease in any children except for two with unusually severe early onset disease. CONCLUSIONS: The progression of ADPKD clearly occurs in childhood and manifests as an increase in cyst number and renal size. This study identifies children at risk for rapid renal enlargement who may benefit the most from future therapeutic interventions.

Adolescent↗