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Biomedical subjects

M A Lewis

Publications and source records attributed to M A Lewis.

At least 19 recordsLinked to original sources
PubMed1996

Third generation oral contraceptives and risk of venous thromboembolic disorders: an international case-control study. Transnational Research Group on Oral Contraceptives and the Health of Young Women.

OBJECTIVE: To test whether use of combined oral contraceptives containing third generation progestogens is associated with altered risk of venous thromboembolism. DESIGN: Matched case-control study. SETTING: 10 centres in Germany and United Kingdom. SUBJECTS: Cases were 471 women aged 16-44 who had a venous thromboembolism. Controls were 1772 women (at least 3 controls per case) unaffected by venous thromboembolism who were matched with corresponding case for age and for hospital or community setting. MAIN OUTCOME MEASURES: Odds ratios derived with stratified analyses and unconditional logistic regression to adjust for potential confounding variables. RESULTS: Odds ratios (95% confidence intervals) for venous thromboembolism were: for any oral contraceptives versus no use, 4.0 (3.1 to 5.3); for second generation products (low dose ethinyl-oestradiol, no gestodene or desogestrel) versus no use, 3.2 (2.3 to 4.3); for third generation products (low dose ethinyloestradiol, gestodene or desogestrel) versus no use, 4.8 (3.4 to 6.7); for third generation products versus second generation products, 1.5 (1.1 to 2.1); for products containing gestodene versus second generation products, 1.5 (1.0 to 2.2); and for products containing desogestrel versus second generation products, 1.5 (1.1 to 2.2). Probability of death due to venous thromboembolism for women using third generation products is about 20 per million users per year, for women using second generation products it is about 14 per million users per year, and for non-users it is five per million per year. CONCLUSIONS: Risk of venous thromboembolism was slightly increased in users of third generation oral contraceptives compared with users of second generation products.

Adolescent↗
PubMed1996

Third generation oral contraceptives and risk of myocardial infarction: an international case-control study. Transnational Research Group on Oral Contraceptives and the Health of Young Women.

OBJECTIVE: To test whether use of combined oral contraceptives containing third generation progestogens is associated with altered risk of myocardial infarction. DESIGN: Matched case-control study. SETTING: 16 centres in Austria, France, Germany, Switzerland, and the United Kingdom. SUBJECTS: Cases were 153 women aged 16-44 with a myocardial infarction event. Controls were 498 women (at least 3 controls per case) unaffected by myocardial infarction who were matched with their corresponding case for age and for hospital or community setting within four months of the index infarction. MAIN OUTCOME MEASURES: Odds ratios derived with stratified analyses and unconditional logistic regression to adjust for potential confounding variables. RESULTS: The estimated odds ratio for myocardial infarction of third compared with second generation oral contraceptives among all 651 study subjects was 0.36 (95% confidence interval 0.1 to 1.2) (P = 0.11). The odds ratio for the United Kingdom and Germany alone was 0.45 (0.1 to 1.8) (P = 0.26). Other odds ratios for the five countries were 3.1 (1.5 to 6.3) (P = 0.003) for use of second generation products v no current use and 1.1 (0.4 to 3.4) (P = 0.9) for use of third generation products v no current use. Among the confounding variables the independent contribution of smoking (for which adjustment was made in the above estimates) proved to be important (10.1 (5.7 to 17.9), P < 0.001). CONCLUSION: An odds ratio of 0.45 with wide confidence intervals shows that third generation oral contraceptives compared with second generation products are associated with a reduced risk of myocardial infarction or with no difference. This finding from an interim analysis should be interpreted with extreme caution. However, the excess risk of venous thromboembolism associated with the use of third generation products may be balanced by the reduced risk of myocardial infarction associated with the same products.

Adolescent↗
PubMed1995

Ecological chaos in the wake of invasion.

Irregularities in observed population densities have traditionally been attributed to discretization of the underlying dynamics. We propose an alternative explanation by demonstrating the evolution of spatiotemporal chaos in reaction-diffusion models for predator-prey interactions. The chaos is generated naturally in the wake of invasive waves of predators. We discuss in detail the mechanism by which the chaos is generated. By considering a mathematical caricature of the predator-prey models, we go on to explain the dynamical origin of the irregular behavior and to justify our assertion that the behavior we present is a genuine example of spatiotemporal chaos.

Animals↗
PubMed1995

Lhermitte-Duclos disease associated with Cowden's disease.

The twelfth patient in the known literature with Lhermitte-Duclos disease (dysplastic gangliocytoma) occurring in association with Cowden's disease is described. The investigation, aetiology, and management of the case are discussed.

Adult↗
PubMed1995

Prevalence of penicillin resistant bacteria in acute suppurative oral infection.

Pus aspirated from acute suppurative oral infections in 78 patients (age range 13-76 years) yielded a total of 331 bacterial strains consisting of 143 facultative anaerobes (predominantly Streptococcus spp.) and 188 strict anaerobes (predominantly Prevotella spp.). Seventy-five isolates (23%) were resistant to penicillin (MIC > 1 mg/L), 37 (11%) were resistant to ampicillin (MIC > 2 mg/L) and 16 (5%) isolates were resistant to amoxycillin/clavulanic acid (MIC > 2 mg/L). Samples from 43 (55%) of the patients yielded at least one penicillin resistant isolate and within this group 30 samples (73%) contained at least one strain which produced beta-lactamase. A history of antibiotic therapy during the 6 months before enrollment in the study did not influence the isolation of penicillin resistant bacteria. It is concluded that penicillin resistant bacteria are often present in the microflora of acute dental infection.

Acute Disease↗
PubMed1995

Multicystic renal dysplasia diagnosed in the antenatal period: a note of caution.

OBJECTIVE: To document the urological problems associated with multicystic renal dysplasia (MCRD), to assess the efficacy of radiological methods for following the natural history of MCRD and to review current experience in the light of historical data regarding this condition. PATIENTS AND METHODS: From January 1982 to December 1992 data were obtained prospectively on 62 patients (41 boys and 21 girls, age range 1-11 years) who had a diagnosis of MCRD suspected on antenatal ultrasonography. All patients had the diagnosis confirmed with radioisotope scans and micturating cystograms. Serum creatinine was measured in each patient and repeated clinically as indicated. Follow-up was from 1 to 11 years, with a clinical review and an annual ultrasonogram. The natural history of these patients was compared with those in other published studies. RESULTS: Of the 62 patients, 12 had associated vesicoureteric reflux. Four patients developed impaired renal function during the course of observation and 10 patients required urological surgery for other pathologies. In the patients managed conservatively, 38% underwent no resolution on sequential ultrasonograms during the 2-year follow-up, and in four children, where complete resolution of the MCRD had occurred on ultrasonography, significant cellular renal masses were excised at subsequent surgery. CONCLUSION: Patients with MCRD have significant associated urological malformations and the natural history in such patients is unpredictable. We do not regard MCRD as an entirely benign condition and feel that all patients require appropriate investigation of their urinary tract and long-term follow-up where conservative treatment is instituted. From the natural history of these patients, reviewed in conjunction with the literature, we recommend that decisions for management can only be taken with the full informed consent of the parents and that surgical excision is offered as part of that process.

Child↗
PubMed1995

Identification of Candida species by PCR and restriction fragment length polymorphism analysis of intergenic spacer regions of ribosomal DNA.

The PCR was used to amplify a targeted region of the ribosomal DNA from 84 Candida isolates. Unique product sizes were obtained for Candida guilliermondii, Candida (Torulopsis) glabrata, and Candida pseudotropicalis. Isolates of Candida albicans, Candida tropicalis, Candida stellatoidea, Candida parapsilosis, and Candida krusei could be identified following restriction digestion of the PCR products.

Base Sequence↗
PubMed1995

Recruiting patients to clinical trials: lessons from studies of growth hormone treatment in renal failure.

Issues raised by the recruitment of children to trials of growth hormone treatment for short stature in chronic renal failure are reported. Information needs of parents and children are discussed, the latter should take account of the children's developmental level and anticipated involvement in decision making. When the incidence of certain side effects is low and probably unquantifiable there are particular problems; failure to include these in information sheets may compromise informed consent but inclusion will, at least for some families, make an already difficult decision even more complicated. A process of recruitment is described which attempts to protect against bias and which balances the requirement to impart neutral information with appropriate clinical involvement in the decision to enter the study. Other functions of the recruitment process are identified. Analysis of understanding and decision making demonstrates that good understanding is neither necessary nor sufficient for ease of decision making. The recruitment process was time consuming and needs planning and funding in future studies. Many of these issues are of general importance for trials of treatment in children.

Adolescent↗
PubMed1995

Drugs, poverty, pregnancy, and foster care in Los Angeles, California, 1989 to 1991.

To determine the characteristics and childbearing histories of women whose infants entered foster care in Los Angeles County, we examined the cases of 1,155 drug-using women whose infants were removed from them at birth and 236 non-drug-using women whose infants were also removed at birth by court order (July 1989 through March 1991). All of the women were indigent, and less than half had graduated from high school. The drug-using women frequently had criminal records, and more than a quarter were homeless. Many comparison women had mental health problems, and some (16.7%) were teenagers under court custody. Overall, 80% of all the children born to both groups of women were under court jurisdiction. Data obtained after study infants' births on 926 drug-using women observed for 18 months revealed that 22% had borne another infant who was placed in foster care; half of these infants had a positive drug immunoassay. Of the 185 non-drug-using women with 18-month follow-ups, 7.6% had borne another child who was in foster care. The magnitude of the repeated childbearing recorded among both groups of women in this study shows that preventive programs including family planning, mental health services, and drug prevention or rehabilitation programs have not reached this population.

Adolescent↗
PubMed1994

The termination of a randomized clinical trial for poor Hispanic children.

OBJECTIVE: To conduct a randomized clinical trial of the Spanish version of an educational program designed to be an adjuvant to adequate medical care of children with asthma. DESIGN: Randomized, clinical trial. SETTING: Los Angeles County, Calif. PARTICIPANTS: One hundred thirty-eight Hispanic children, ages 7 to 12 years, from disadvantaged families. All had used emergency facilities of major local hospitals in the previous year. MEASUREMENT/MAIN RESULTS: As the study proceeded, it became apparent that subjects were receiving inadequate medical and nursing care and had numerous barriers to applying knowledge and self-care skills gained from the program. Realizing this, we considered it unethical to allow the control children to suffer for the duration of the trial (1 year). Therefore, all children received "adequate" care from the research staff, and the randomized clinical trial, as originally designed, was ended. The emergency department/hospital use by both groups was significantly reduced compared with previous experience. CONCLUSION: Those researchers conducting randomized trials involving poor children should be aware of the potential ethical problems inherent in such ventures.

Asthma↗
PubMed1994

Orofacial artefactual disease.

Self-induced lesions of the face and mouth may occasionally be encountered in dental practice. In general the deliberate creation of orofacial lesions is an indication of underlying psychiatric disease of various types that usually involve a personal gain by the patient from having such lesions. We present three cases of deliberately self-induced lesions and discuss the problem of diagnosis and management of these cases.

Adult↗
PubMed1994

When are dysphoric individuals distressing to others and vice versa? Effects of friendship, similarity, and interaction task.

Interpersonal relationships present difficulties for dysphoric individuals, but the specific contexts in which these difficulties arise remain poorly understood. The authors examined several factors hypothesized to affect how dysphoric and nondysphoric individuals react to each other. Female college students interacted with either a friend or stranger who had a similar or dissimilar dysphoria status in three tasks: a causal conversation, disclosure of a personal problem to the partner, and response to the partner's disclosure of a personal problem. Ss' moods, evaluations of their partners, and verbal behaviors were assessed. Dysphoric Ss exhibited characteristic negative mood and verbal content but did not elicit negative reactions from their partners. Negative reactions were most evident in dysphoric Ss' responses to dissimilar (nondysphoric) strangers, underscoring the need for greater attention to dysphoric individuals' perspective on their social interactions.

Female↗
PubMed1994

Investigative techniques and renal parenchymal damage in children with spina bifida.

The case records of 72 patients attending a multidisciplinary spina bifida clinic were reviewed to discover the prevalence of renal parenchymal damage. 19.4% of the total population had such damage. More detailed analysis of the group according to age showed that the prevalence of parenchymal damage in the over ten year olds (27.3%), was twice that of the under five year olds (13.3%) but the same as the prevalence of "at risk" patients (26.6%) in this group. On the basis that most renal parenchymal damage occurs early we conclude that the current approach to investigation and treatment is reducing the incidence of renal parenchymal damage in this population. Further reduction would require the early identification of the high risk bladder before the onset of hydronephrosis.

Adolescent↗