Biomedical subjects

T Hillen

Publications and source records attributed to T Hillen.

10 recordsLinked to original sources

PubMed2003

Cattaneo models for chemosensitive movement. Numerical solution and pattern formation.

We derive models for chemosensitive movement based on Cattaneo's law of heat propagation with finite speed. We apply the model to pattern formation as observed in experiments with Dictyostelium discoideum, with Salmonella typhimurium and with Escherichia coli. For Salmonella typhimurium we make predictions on pattern formation which can be tested in experiments. We discuss the relations of the Cattaneo models to classical models and we develop an effective numerical scheme.

Animals↗

PubMed2003

Cattaneo models for chemosensitive movement: numerical solution and pattern formation.

Animals↗

PubMed2003

Self ratings of health predict functional outcome and recurrence free survival after stroke.

STUDY OBJECTIVE: To measure stroke victims' self rated health (SRH) status and SRH transition, and to compare how the two are prospectively associated with disability and recurrence free survival. DESIGN: Prospective case registry study with face to face follow up interviews at three months, one, two, and three years. Ascertained were SRH status and SRH transition using single question assessments, Barthel Index (BI), Frenchay Activities Index (FAI), and Mini Mental State Examination (MMSE). SETTING: A multiethnic inner city population of 234 533. PARTICIPANTS: Patients surviving the initial three months after a first in a lifetime stroke in 1995 to 1998. RESULTS: Of 690 stroke survivors 561 (81.3%) could complete the self report items. Answers to the item on SRH status did not vary significantly between the four follow up interviews. However, responses to the item on SRH transition changed significantly during follow up with three months ratings being more negative than all subsequent ratings. SRH transition, but not SRH status, showed a prospective association with long term outcome in multivariate analyses controlling for the BI, FAI, and MMSE. Compared with all other patients, patients reporting "Much worse health" at three months were more likely to be disabled ( = BI<20) at one year (OR 6.29, 95% CI 2.26 to 17.52) and their combined risk of stroke recurrence and death was increased over five years (HR 1.72, 95% CI 1.25 to 2.38). CONCLUSIONS: Items on SRH should be used with caution in populations with high rates of disability and language problems, as many participants are unable to complete them. SRH transition may be a better predictor of disability and recurrence free survival after major medical events than SRH status.

Aged↗

PubMed2002

Incidence and case fatality rates of stroke subtypes in a multiethnic population: the South London Stroke Register.

OBJECTIVE: To identify sociodemographic differences in the incidence of the subtypes of first ever stroke in a multiethnic population. METHODS: A prospective community stroke register (1995-8) was developed using multiple notification sources and pathological and clinical classifications of stroke. Standardisation of rates was to European and World populations and adjusted for age, sex and socioeconomic status in multivariate analyses. A multiethnic population of 234 533 in south London, of whom 21% are black was studied. RESULTS: A total of 1254 cases were registered. The average age of stroke was 71.7 years with black patients being 11.3 years younger than white patients (p<0.0001). The incidence rate/1000 population was 1.33 (crude) (95% CI 1.26 to 1.41), 1.28 (European adjusted) (95% CI 1.2 to 1.35) with a 2.18 (95% CI 1.86 to 2.56) (p<0.0001) age and sex adjusted incidence rate ratio in the black population. Radiological diagnosis was confirmatory in 1107 (88.3%) with 862 (68.7%) infarction, 168 (13.4%) primary intracerebral haemorrhage, and 77 (6.2%) subarachnoid haemorrhage. Of the cerebral infarction cases 189 (21.9%) were total anterior circulatory, 250 (29%) partial anterior, 141 (16.4%) posterior (POCI) and 282 (32.7%) lacunar infarcts. The black group had a significantly higher incidence of all subtypes of stroke except for POCI and unclassified strokes. The incidence rate ratio (IRR) for men compared with women was 1.34 (95% confidence interval (95% CI) 1.19 to 1.50; p<0.001). The IRR for manual versus non-manual occupations in those aged 35-64 years was 1.64 (95%CI 1.22 to 2.23; p<0.0001). There was a borderline significant increase in adjusted survival at 6 months in the black group 95% (CI 0.61 to 1.03, p=0.078) with a hazard ratio of 0.79 after adjustment and stratification. CONCLUSIONS: Although the black population is at increased risk of stroke and most subtypes of stroke, this is not translated into significant differences in survival. Hence black/white differences in mortality are mainly driven by incidence of stroke. There are striking demographic inequalities in the risk of stroke in this multiethnic inner city population that need to be tackled through interagency working. Although the reasons for the increased risk in the black population are unclear, demographic factors such as socioeconomic status do seem to play a significant independent part.

Adolescent↗

PubMed2000

DHEA-S plasma levels and incidence of Alzheimer's disease.

BACKGROUND: Cross-sectional studies controlling for age and gender reported a relationship between Alzheimer's disease and low dehydroepiandrosterone sulphate (DHEA-S) plasma levels. Prospective data with sufficient control for confounding factors are lacking. METHODS: A nested case-control study examined baseline DHEA-S in participants of the Berlin Aging Study. Cases (n = 14) developed dementia of the Alzheimer type within 3 years. Control group A (n = 14) was matched for gender, age, multimorbidity, and immobility. Control group B (n = 13) was matched for gender and age and comprised participants free from multimorbidity, immobility, multimedication, need of help, incontinence, visual impairment, hearing impairment, and depression. RESULTS: The mean plasma DHEA-S concentration of case subjects was 1.02 +/- 0.61 mumol/L. Both control groups had higher mean DEHA-S levels, in control group A, it was 1.89 +/- 1.24 mumol/L (p = .012) and in control group B 1.70 +/- 1.38 mumol/L (p = .093). CONCLUSIONS: This population-based prospective study supports the role of DHEA-S as a risk factor for Alzheimer's disease.

Aged↗

PubMed2000

Carotid atherosclerosis, vascular risk profile and mortality in a population-based sample of functionally healthy elderly subjects: the Berlin ageing study.

OBJECTIVES: Studies on extracranial carotid atherosclerosis have predominately been undertaken on middle-aged subjects. This study examines the prevalence of extracranial carotid atherosclerosis, its relation to vascular risk factors and its significance for survival in elderly subjects. DESIGN: Population-based cross-sectional survey. Non-modifiable vascular risk factors examined were family history of atherosclerotic disease, sex and apolipoprotein E (apoE) genotype. Potentially modifiable risk factors assessed were smoking, fibrinogen, fasting lipids, body mass index, hypertension and diabetes. SETTING AND SUBJECTS: Two hundred and twenty-five functionally healthy volunteers of the Berlin Ageing Study, aged 70-100. MAIN OUTCOME MEASURES: Presence of carotid stenosis and plaque ascertained by ultrasound imaging; 5-year mortality. RESULTS: At least one plaque was found in 144 (64%) of the volunteers; 34 (15%) had a stenosis over 50%; and nine (4%) had a stenosis over 75%. Total cholesterol > 6.5 mmol L-1, LDL cholesterol > 4.6 mmol L-1 and total cholesterol/HDL cholesterol ratio > 5 were significantly associated with presence of plaque in 70- to 80-year-old subjects, as was diabetes in subjects over 80 years. Log-linear analyses showed significant three-way interactions for high LDL cholesterol and diabetes with plaques and age. Family history, sex, apoE genotype, smoking and fibrinogen were not related to presence of plaque in the study population. Cox regression analysis revealed increased 5-year mortality rates for subjects with plaques (OR = 2. 88; 95% CI = 1.30-6.35), whereas the vascular risk profile was not associated with mortality. CONCLUSIONS: In a population-based sample of functionally healthy elderly subjects, the significance of the vascular risk profile seemed to be diminished. It had no impact on survival and only modifiable risk factors showed an age-dependent association with carotid disease.

Age Factors↗

PubMed2000

Ventilatory capacity and risk for dementia.

BACKGROUND: Previous studies have found a relationship between single indicators of ventilatory capacity and measures of cognitive function, but have not addressed dementia specifically. This study examined the relationship between different indicators of ventilatory capacity and dementia, diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition, controlling for important confounding factors. METHODS: Cross-sectional data on participants (n = 437) of the Berlin Aging Study (BASE), which are representative of former West Berlin's living population aged 70 years and older, were analyzed. Ventilatory capacity was measured by spirometry as peak expiratory flow rate (PEF-R), forced expiratory volume in 1 second (FEV-1), maximal expiratory flow at 50% of forced vital capacity (MEF50%FVC), and maximal expiratory flow at 25% of forced vital capacity (MEF25%FVC). Odds ratios (OR) for dementia associated with ventilatory capacity were obtained by logistic regression, adjusting for age, gender, education, ApoE4 status, chronic obstructive pulmonary disease, smoking, heart failure, visual and auditory functioning, grip strength, and former physical activity. RESULTS: Separate analyses for PEF-R, FEV-1, MEF50%FVC, and MEF25%FVC revealed significantly increased odds for dementia among subjects in the lowest compared with the best functioning group in ventilatory testing. The OR associated with PEF-R > or = 2 l/s was found to be 20.4 (confidence interval [CI] 5.1-82.7). For FEV-1, MEF50%FVC, and MEF25%FVC ORs of 7.5 (CI 2.1-27.9), 4.3 (CI 1.5-12.5), and 4.7 (CI 1.3-17) were obtained, respectively. CONCLUSIONS: Ventilatory capacity, measured by spirometry in a representative sample of very elderly people, is cross-sectionally related to dementia. Taking evidence from longitudinal studies into account, this result suggests that decreased respiratory function may increase the risk for dementia, independent from already known risk factors.

Aged↗

PubMed2000

Self rating of health is associated with stressful life events, social support and residency in East and West Berlin shortly after the fall of the wall.

STUDY OBJECTIVE: To compare the health status and factors influencing the health of populations that had previously lived under different political systems. DESIGN: Cross sectional health and social survey using postal interviews. The relation between self reported health and psychosocial factors (stressful life events, social support, education, health promoting life style and health endangering behaviour) was investigated. To determine East-West differences a logistic regression model including interaction terms was fitted. SETTING: East and West Berlin shortly after reunification 1991. PARTICIPANTS: Representative sample of 4430 Berlin residents aged 18 years and over (response rate 63%). RESULTS: Of all respondents, 15.4% rated their health as unsatisfactory. Residents of East Berlin rated their health more frequently as unsatisfactory than residents of West Berlin (Or(age adjusted)= 1.29, 95%CI 1.08, 1.52), these differences occurred predominantly in the over 60 years age group. Logistic regression showed significant independent effects of stressful life events, social support, education, and health promoting life style on self rated health. The effects of education and health promoting life style were observed to be more pronounced in the western part of Berlin. Old age and female sex showed a stronger association with unsatisfactory health status in the eastern part of Berlin. CONCLUSIONS: For subjects aged over 60 years there was evidence that living in the former East Berlin had an adverse effect on health compared with West Berlin. The impact of education and a health promoting lifestyle on self rated health seemed to be weaker in a former socialist society compared with that of a Western democracy. This study supports an "additive model" rather than a "buffering model" in explaining the effects of psychosocial factors on health.

Adolescent↗

PubMed2000

Antithrombotic and antihypertensive management 3 months after ischemic stroke : a prospective study in an inner city population.

BACKGROUND AND PURPOSE: We sought to examine the frequency, predictors, and effects of nontreatment with antithrombotic and antihypertensive therapies 3 months after ischemic stroke. METHODS: The population-based South London Community Stroke Register prospectively collected data on first-in-a-lifetime strokes between 1995 and 1997. Among patients registered with ischemic stroke, treatment status with antithrombotic and antihypertensive therapies was examined 3 months after the event. RESULTS: In a cohort of 457 patients with ischemic stroke, 393 (86.0%) were considered appropriate for antiplatelet medication, 32 (7.0%) for anticoagulant medication, and 254 (55.9%) for antihypertensive medication. The rates of nontreatment observed 3 months after the event were 24.4% for antiplatelet, 59.4% for anticoagulant, and 29.5% for antihypertensive medication. Independent risk factors for nontreatment with antithrombotic therapies (antiplatelets and anticoagulants) were the subtype of stroke (nonlacunar infarct: OR=1. 60, 95% CI 1.07 to 2.54), stroke severity measured by the Glasgow Coma Scale (GCS) score (GCS </=13: OR 2.08, 95% CI 1.18 to 3.66) and the Barthel Index (BI) score 5 days after the event (BI </=10: OR 1. 85, 95% CI 1.17 to 2.93). For antihypertensive therapies the stroke subtype (OR 2.46, 95% CI 1.33 to 4.54), GCS score (OR 2.97, 95% CI 1. 35 to 6.53), BI score (OR 2.33, 95% CI 1.27 to 4.29), and ethnicity (Caucasian: OR 2.43, 95% CI 1.15 to 5.14) were independently associated with nontreatment. Cox regression modeling showed no significant association between the treatment status and recurrence-free 3-year survival rates after controlling for severity and subtype of stroke. CONCLUSIONS: Secondary prevention for a common disease such as stroke appears to be inadequate in the study area. Healthcare professionals need to consider antithrombotic and antihypertensive therapies for all stroke patients.

Adult↗

PubMed1999

[Intraoperative changes in arterial end tidal CO2 partial pressure difference in interventions with constant ventilation-perfusion ratio].

During general anaesthesia, the endtidal CO2 pressure serves as an estimate of the arterial CO2 pressure to regulate the ventilator setting. Important arterial to end-tidal carbon dioxide tension differences (P(a-et)CO2) have been observed among patients undergoing procedures which have substantial impact on the ventilation-perfusion ratio (V/Q). Data on the P(a-et)CO2 for procedures in which the V/Q-ratio remains constant are lacking. Repeated measurements of P(a-et)CO2 in twelve patients with chronic obstructive lung disease (COLD) and nine pulmonary healthy patients undergoing jaw surgery were performed. The P(a-et)CO2 in the pulmonary healthy subjects (5.96 +/- 1.68 mmHg) was lower than in the COLD patients (9.05 +/- 3.49 mmHg) (p < 0.01). A clinically significant P(a-et)CO2 > or = 8 mmHg was observed in 52% of the measurements in patients with COLD compared with 11% in the pulmonary healthy subjects (p < 0.01). Both patient groups showed only minimal intraoperative changes of P(a-et)CO2. The deviation of all subsequent P(a-et)CO2 values from the initial P(a-et)CO2 was 2.17 +/- 1.52 mmHg in the pulmonary healthy patients and 2.02 +/- 1.49 mmHg in the patients with COLD (p = 0.76). Intraoperative changes of the P(a-et)CO2 are small during procedures with no major alterations of the V/Q ratio. For these procedures an initial measurement of the P(a-et)CO2 in patients with lung disease should be sufficient. In pulmonary healthy subjects the P(a-et)CO2 seems to be negligible.

Adult↗