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Biomedical subjects

E L Simpson

Publications and source records attributed to E L Simpson.

18 recordsLinked to original sources
PubMed2001

Venous thromboembolism in pregnancy and the puerperium: incidence and additional risk factors from a London perinatal database.

OBJECTIVE: To determine the incidence of venous thromboembolism in pregnancy and the puerperium and to identify risk factors for pregnancy-related venous thromboembolism. DESIGN: Cohort study and case-control study. SETTING: London, UK. POPULATION: 395,335 women with live births or pregnancies of 24 or more weeks of gestation between 1988 and 1997. METHODS: Data extraction from the St Mary's Maternity Information System database. Random sample of 5% for case-control study. MAIN OUTCOME MEASURES: Incidence of venous thromboembolism; odds ratios for variables associated with venous thromboembolism. RESULTS: The incidence of venous thromboembolism was 85/100,000 maternities. There were approximately twice as many postpartum as antepartum events. Blood group A, multiple pregnancy, caesarean section, cardiac disease, delivery at gestational age of < 36 weeks, a body mass index of > or = 25, or more and maternal age of 35 or over were all found to increase incidence of venous thromboembolism. CONCLUSIONS: Although venous thromboembolism is the leading cause of maternal deaths in the UK, it is still a rare event. Most of these events are deep vein thromboses occurring in the postpartum period. Antenatally multiple birth is an important risk factor. Postnatally women who have had a caesarean section, premature delivery or history of cardiac disease should be assessed carefully for venous thromboembolism.

Adult↗
PubMed2000

Perirhinal cortex ablation in rats selectively impairs object identification in a simultaneous visual comparison task.

In Experiment 1, rats discriminated among computer-generated visual displays (scenes) comprising 3 different shapes (objects). One constant scene (unrewarded) appeared on every trial together with a trial-unique variable scene (rewarded). Four types of variable scene were intermingled: (a) unfamiliar objects in different positions from the constant; (b) unfamiliar objects in same positions as the constant; (c) same objects as the constant in different positions; (d) same objects and positions, recombined. Aspiration lesions of perirhinal cortex impaired performance with type (b) only. Experiment 2 tested spatial delayed nonmatching-to-sample. The perirhinal group were impaired nonsignificantly, and less than fornix-transected rats in an earlier study. Rats' perirhinal cortex, like monkeys', subserves object identification in the absence of memory requirement but does not contribute substantially to hippocampal system spatial memory function.

Animals↗
PubMed2000

Rapid visual learning in the rat: effects at the 5-HT1a receptor subtype.

The 5-hydroxytryptamine1a (5-HT1a) receptor agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT; 0.15 mg/kg) impaired rats' rapid visual learning on a computerized maze. This treatment also increased decision time (DT) but the learning impairment was not necessarily a side-effect of slower responding because, in this task, responses made at long DT are more accurate than those at short DT. The selective 5-HT1a receptor antagonist WAY-100635 (0.3 mg/kg) was itself without effect on accuracy, but was effective in reversing effects of 8-OH-DPAT (on both accuracy and DT). Within problems (i.e., over the 40-60 trials of a single discrimination), performance was reduced by treatment with 8-OH-DPAT at all stages of learning. We conclude that this effect is mediated through the 5-HT1a receptor site (rather than through some other serotonergic receptor site or non-specific mechanism) as it was reversible by treatment with WAY-100635. Although it could still arise from behaviourally non-specific effects, the performance deficit finds its best account in terms of the psychological processes necessary to visual learning. Its reversal with WAY-100635 offers support to the hypothesis that 5-HT1a receptor antagonists could improve cognitive function, under conditions of pre-existing impairment due to overactive serotonergic inhibition, as is thought to occur in Alzheimer's disease.

Analysis of Variance↗
PubMed2000

The effects of age, body mass index, smoking and general health on the risk of venous thromboembolism in users of combined oral contraceptives.

OBJECTIVES: To investigate the factors associated with idiopathic venous thromboembolism in combined oral contraceptive users and to estimate the crude and age-specific incidence rates ofidiopathic venous thromboembolism among this population. METHODS: The UK MediPlus Database and the General Practice Research Database were searched to identify women with evidence of venous thromboembolism while exposed to combined oral contraceptives. Cohort and nested case-control studies were carried out using the same methodology on both databases. We conducted a meta-analysis using the individual data for the cases and controls from the two case-control studies to identify factors associated with idiopathic venous thromboembolism in women using combined oral contraceptives. RESULTS: The incidence rate of idiopathic venous thromboembolism among oral contraceptive users was 39.4 per 100,000 exposed woman-years. The age-specific incidence rates were found to rise sharply after the age of 39 years. Factors identified as being significantly associated with idiopathic venous thromboembolism in women using combined oral contraceptives were: body mass index of 25 kg/m2 and over, the association rising dramatically in women with a body mass index of 35 kg/m2 or more; smoking; general ill health; and asthma. CONCLUSION: We believe that, before prescribing combined oral contraceptives, the venous as well as the arterial factors need to be considered and, in addition, age, obesity and smoking are all relevant when assessing an individual patient's risk.

Adolescent↗
PubMed1999

Scene and object vision in rats.

Dark Agouti rats learned to discriminate large visual displays ("scenes") in a computer-controlled Y-maze. Each scene comprised several shapes ("objects") against a contrasting background. The constant-negative paradigm was used; in each problem, one constant scene was presented on every trial together with a trial-unique variable scene, and rats were rewarded for approaching the variable scene. By varying the manner in which variables differed from the constant, we investigated what aspects of scenes and the objects comprising them were salient. In Experiment 1, rats discriminated constant scenes more easily if they contained four objects rather than six, and they showed a slight attentional bias towards the lower halves of the screens. That bias disappeared in Experiment 2. Experiments 3 and 4 showed that rats could discriminate scenes even if the objects that comprised them were closely matched in position, luminance, and area. Therefore, they encoded the form of individual objects. Rats perceived shapes of the same class (e.g. two ellipses) as more similar than shapes from different classes (e.g. ellipse and polygon) regardless of whether they also differed in area. This paradigm is suitable for studying the neuropsychology of perceiving spatial relationships in multi-object scenes and of identifying visual objects.

Animals↗
PubMed1998

Eccrine syringofibroadenomatosis associated with hidrotic ectodermal dysplasia.

Eccrine syringofibroadenoma (ES) is generally regarded as a solitary benign adnexal neoplasm of the skin. Recently, the epithelial and stromal changes of this lesion have been recognized as being a reaction pattern in certain settings. We describe two individuals in whom this process was a manifestation of hidrotic ectodermal dysplasia. In both cases, the diagnosis had been missed for many years and the process had been thought to be a manifestation of an inflammatory dermatosis of the palms and soles. In both instances, other family members were found to be affected. Thus, ES may be manifested clinically as erythematous erosive plaques, especially of the palms and soles. It is important that clinicians be familiar with this disorder and be aware that it may exhibit unusual cutaneous manifestations.

Aged↗
PubMed1996

Extraskeletal soft tissue masses of Langerhans' cell histiocytosis.

Typically, soft-tissue involvement with Langerhans' cell histiocytosis (LCH) is the result of extension from adjacent bone marrow. We present a patient who developed soft-tissue masses of LCH, which did not arise as a result of extension from bone marrow, but instead produced extrinsic cortical erosion, preserving the marrow signal on MRI.

Adult↗
PubMed1988

Hyperdense pelvic and inguinal lymph nodes.

This small series reports on the computed tomography appearance of hyperdense iliac, inguinal, and femoral lymph nodes in four cases of lymphoma and one case each of ovarian and breast carcinoma. The mean attenuation value of the lymph nodes was 93.8 Hounsfield units (HU), compared to 61 HU for adjacent muscle and 110.7 HU for blood vessels. A relatively homogeneous enhancement pattern was noted, which could not be directly related to hypervascularity, inflammation, or previous treatment with drugs or radiation.

Adult↗
PubMed1986

Computed tomography in the diagnosis of renal pseudotumors.

If the initial evaluation of the urinary tract raises the possibility of renal mass, one must decide what study or studies to perform to confirm or deny its presence. Radionuclide imaging has been the study of choice in this situation. Six cases are presented in which computed tomography definitively demonstrated that a suspicious renal mass represented normal renal parenchyma. Comparison with other renal imaging modalities is discussed.

Adult↗
PubMed1983

Absence of parathyroid hormone messenger RNA in nonparathyroid tumors associated with hypercalcemia.

We used a sensitive and specific hybridization assay that detects evidence of parathyroid hormone synthesis in tumors to investigate whether this hormone mediates the hypercalcemia of malignant disease. The assay uses radiolabeled, cloned parathyroid hormone DNA to hybridize selectively with parathyroid hormone messenger RNA. We assayed 13 human and 3 animal tumors of diverse cell origins that are frequently associated with the hypercalcemia of cancer. Five of the human tumors were obtained from patients known to be hypercalcemic at the time of tumor excision, two were from normocalcemic patients, and six were from patients with breast cancer whose serum calcium levels were unknown. Messenger RNA was prepared from cultured cell lines or tumors; active RNA fractions were hybridized with either human or bovine cloned parathyroid hormone DNA that had been labeled to a high specific activity with [32P]nucleotide. We were unable to detect parathyroid hormone RNA transcripts in any of the tumors. Our results indicate that parathyroid hormone rarely, if ever, causes hypercalcemia in malignant disease.

Adult↗
PubMedDate not supplied

Effect of 1995 pill scare on rates of venous thromboembolism among women taking combined oral contraceptives: analysis of general practice research database.

OBJECTIVE: To compare the incidence of venous thromboembolism among women taking combined oral contraceptives before and after the October 1995 pill scare. DESIGN: Analysis of General Practice Research Database. SETTING: United Kingdom, January 1993 to December 1998. SUBJECTS: Women aged 15-49 taking combined oral contraceptives. MAIN OUTCOME MEASURES: Incidence of venous thromboembolism. RESULTS: Use of so called "third generation" combined oral contraceptives fell from 53% during January 1993 to October 1995 to 14% during November 1995 to December 1998. There was no significant change in the incidence of venous thromboembolism between the two periods after age was adjusted for (incidence ratio 1.04, 95% confidence interval 0.78 to 1.39). CONCLUSIONS: The findings are not compatible with the assertion that third generation oral contraceptives are associated with a twofold increase in risk of venous thromboembolism compared with older progestogens.

Adolescent↗