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PubMed1999

The graft versus leukemia effect after bone marrow transplantation: a case study using structural nested failure time models.

Over the last decade, J. M. Robins has developed a set of tools for assessing, from observational data, the causal effects of a time-dependent treatment or exposure in the presence of time-dependent covariates that may be simultaneously confounders and intermediate variables. This report concerns a case study of the application of one these techniques, G-estimation using structural nested failure time models, to the problem of assessing the effect of graft versus host disease on leukemia relapse after bone marrow transplantation.

Biometry↗
PubMed2003

Need for recovery from work related fatigue and its role in the development and prediction of subjective health complaints.

AIMS: To present the available empirical evidence for the assumed position of the concept of work related fatigue as: (1) short term effect of the working day; and (2) an intermediate variable between work demands and the development of subjective health complaints and sickness absence. METHODS: Results from six single occupation studies, conducted between 1996 and 2002, are presented. Work demands (working hours, decision latitude, break control/autonomy, and mental, emotional, and physical demands) were assessed through validated scales. Work related fatigue was represented and assessed by means of the need for recovery after working time scale in all studies. Subjective health complaints and duration of sickness absence were quantified with the same instruments in most studies as well. Both cross sectional studies (four) as well as prospective studies (two; up to two years follow up) were performed. Cross sectional data of 3820 workers, in total, were available. Prospective data were accessible for 1200 workers in industry and health care. Models were tested with stepwise multiple regression analyses. RESULTS: Strong associations between work demands and need for recovery were found in different occupations. The variance explained in need for recovery by work demands, age, and (baseline) need for recovery ranged between 14% and 48% in both types of studies. The amount of explained variance by work demands, age, and (baseline) need for recovery in subjective health complaints ranged between 24% and 58% in the different occupations. The prospective data showed the prognostic value of need for recovery in relation to subjective health complaints (in terms of psychosomatic complaints, emotional exhaustion, or sleep problems) and duration of future sickness absence. CONCLUSIONS: The hypothesised role for work related fatigue as a link in the causal string of events, that is assumed to exist between repeated adverse work demands and the development of work related stress reactions, (psychological) overload and, eventually, health problems, was confirmed.

Adult↗
PubMed1999

Physical activity and ischemic stroke risk. The atherosclerosis risk in communities study.

BACKGROUND AND PURPOSE: The relationship between physical activity and stroke is inconclusive according to the 1996 US Surgeon General's Report on Physical Activity and Health. Therefore, this study examined the relationship between physical activity and ischemic stroke risk among 14 575 Atherosclerosis Risk in Communities Study participants aged 45 to 64 years free of self-reported stroke and coronary heart disease at baseline. METHODS: Eligible potential stroke hospitalizations were identified from ongoing hospital surveillance and from hospitalizations reported by the cohort study participants. All strokes were validated by hospitalization records. Physical activity was measured as sport, leisure (nonsport), and work with the use of the Baecke questionnaire. Multivariable Poisson and Cox proportional hazards models were used to determine the association of differing levels of physical activity with ischemic stroke incidence. RESULTS: During an average of 7.2 years of follow-up, 189 incident ischemic strokes occurred. Ischemic stroke incidence rates were highest in the lowest quartile of sport, leisure, and work scores. The hazard rate ratios with 95% CIs for ischemic stroke for the highest quartile compared with the lowest quartile of activity adjusted for age, sex, race-center, education, and smoking, were sport 0.83 (0.52, 1.32), leisure 0.89 (0.57, 1.37), and work 0.69 (0.47, 1.00). Further adjustment for factors that likely were intermediate variables (hypertension, diabetes, fibrinogen, and body mass index) between physical activity and stroke attenuated the associations. CONCLUSIONS: Our findings suggest that physical activity was weakly associated with a reduced risk of ischemic stroke among middle-aged adults. The association may be due to links between physical activity and other risk factors or due to chance.

Brain Ischemia↗
PubMed2003

Cost effectiveness of a multi-stage return to work program for workers on sick leave due to low back pain, design of a population based controlled trial [ISRCTN60233560].

BACKGROUND: To describe the design of a population based randomized controlled trial (RCT), including a cost-effectiveness analysis, comparing participative ergonomics interventions between 2-8 weeks of sick leave and Graded Activity after 8 weeks of sick leave with usual care, in occupational back pain management. METHODS DESIGN: An RCT and cost-effectiveness evaluation in employees sick-listed for a period of 2 to 6 weeks due to low back pain. Interventions used are 1. Communication between general practitioner and occupational physician plus Participative Ergonomics protocol performed by an ergonomist. 2. Graded Activity based on cognitive behavioural principles by a physiotherapist. 3. Usual care, provided by an occupational physician according to the Dutch guidelines for the occupational health management of workers with low back pain. The primary outcome measure is return to work. Secondary outcome measures are pain intensity, functional status and general improvement. Intermediate variables are kinesiophobia and pain coping. The cost-effectiveness analysis includes the direct and indirect costs due to low back pain. The outcome measures are assessed before randomization (after 2-6 weeks on sick leave) and 12 weeks, 26 weeks and 52 weeks after first day of sick leave. DISCUSSION: The combination of these interventions has been subject of earlier research in Canada. The results of the current RCT will: 1. crossvalidate the Canadian findings in an different sociocultural environment; 2. add to the cost-effectiveness on treatment options for workers in the sub acute phase of low back pain. Results might lead to alterations of existing (inter)national guidelines.

Cost-Benefit Analysis↗
PubMed1990

Inhibin and estradiol responses to ovarian hyperstimulation: effects of age and predictive value for in vitro fertilization outcome.

We have compared the time courses of serum inhibin and estradiol responses to ovarian hyperstimulation in patients undergoing in vitro fertilization and embryo transfer as well as their predictive value for outcome of intermediate variables and pregnancy in in vitro fertilization and embryo transfer. Blood samples (n = 749) were collected for up to 6 days before hCG administration in 100 consecutive treatment cycles, of which 44 resulted in pregnancy, as defined by elevated luteal phase serum hCG beta levels. Inhibin and estradiol levels increased markedly in parallel during hyperstimulation and were highly correlated (r = 0.89; P less than 0.001). Inhibin responses were significantly lower in women 35 yr of age or older (P less than 0.001), although estradiol responses were not influenced by age. Gravidity and tubal disease also had marginal effects on the time course of inhibin responses, but not on overall mean inhibin levels or estradiol responses. The time course of hormonal responses to hyperstimulation was not influenced by any other demographic or etiological factors. Peak values of both hormones correlated with the total number of follicles (inhibin, r = 0.70; estradiol, r = 0.65; P less than 0.001) and oocytes retrieved per cycle (inhibin, r = 0.49; estradiol, r = 0.39; P less than 0.001). The time course and peak values of inhibin and estradiol responses to hyperstimulation did not differ significantly between conception or nonconception cycles whether judged by biochemical (luteal hCG beta) or clinical (viable ongoing pregnancy) criteria. Luteal phase serum inhibin, estradiol, progesterone, and hCG levels were significantly higher in conception than in nonconception cycles (P less than 0.001). These data suggest that the rises in serum inhibin and estradiol levels during hyperstimulation have similar predictive properties for IVF-ET outcomes and could, therefore, be used interchangeably to monitor hyperstimulation regimens. The age-related reduction in inhibin, but not estradiol, responses suggests that these two hormones reflect different granulosa cell functions and that serum inhibin responses to maximal ovarian stimulation may be a sensitive and early index of declining ovarian function with advancing age.

Adult↗
PubMedDate not supplied

Regulation and function of the fetal adrenal gland in sheep.

It is now known that in some species (sheep, cow, pig, llama) the fetal adrenal cortex is capable of secreting cortisol both early and late in gestation, but not during some, variable, intermediate time period. In the sheep the fetal adrenal can secrete cortisol, and respond quickly to ACTH, both between 40-90 days of gestation, and from 120-150 days (term), but not between 90-120 days. The inability to secrete cortisol in this 'off' period is due to lack of adequate pituitary ACTH at this time to maintain expression of P-450(17 alpha and P-450scc. Recent experiments demonstrate that the fetal pituitary does secrete adequate amounts of ACTH to keep these genes expressed, in the 40-90 day period. The question now becomes, therefore, what regulates the triphasic secretion pattern of ACTH during fetal sheep development.

Adrenal Glands↗
PubMed1987

Genetic variation and differentiation of three Schistosoma species from the Philippines, Laos, and Peninsular Malaysia.

Electrophoretically-detected allozyme variation is described in strains of Schistosoma japonicum (4 Philippine strains), S. mekongi (Laos), and an undescribed anthropophilic S. japonicum-like schistosome from Peninsular Malaysia. Result, together with those reported previously for 8 other strains (S. japonicum, China, Formosa, Japan, Philippines; S. mekongi, 2 substrains; Malaysian schistosome, 2 strains) permit a composite genetic characterization of 15 strains of Asian schistosomes at 9-18 presumptive loci. The proportion of polymorphic loci (P) and the mean heterozygosity per locus (H) were zero in all strains. Although this was expected for strains that had been in laboratory culture for up to 50 years, we expected to detect variation in strains based on 10-50 recently field-collected infected snails. We expected S. japonicum to be as variable as S. mansoni (P = 0.13 (0-0.33), H = 0.04, 18 loci, 22 strains) as it is believed to reproduce sexually, has an evolutionary history of several million years, inhabits a wide geographic range, coevolved with a genetically variable intermediate snail host, and has a diversity of mammalian hosts. No differences were detected between the 5 S. japonicum strains from Leyte and Luzon (Philippines), between the 3 S. mekongi strains, or between the 3 Malaysian schistosome strains; these groups and the remaining S. japonicum strains representing Mindoro (Philippines), China, Formosa, and Japan each have distinctive multilocus electromorphic patterns. Nei's genetic distances (D) were calculated to estimate interstrain and interspecific divergence. Interstrain genetic distances in S. japonicum averaged greater than 0.3; much higher than those reported previously for S. mansoni (D = 0.06, D(max) = 0.24). S. japonicum (Mindoro) was moderately differentiated from the Leyte-Luzon strains (D = 0.29, 12 loci). Estimates of the S. japonicum China-Philippine distance (D greater than 0.4, 11 loci) are high for conspecific populations and further studies of the still poorly characterized Chinese parasite may reveal that these are, in fact, separate species. S. japonicum is shown to be only distantly related to S. mekongi and the Malaysian schistosome (D greater than 1); the latter is closely related to, but genetically quite distinct from, S. mekongi (D = 0.61 +/- 0.275, 11 loci) and warrants recognition as a new species. The medical significance of the isogenic nature of the Asian schistosome strains and their evolutionary divergence are discussed.

Animals↗
PubMedDate not supplied

[The Cambridge Cognitive Examination as a tool for detection of dementia].

INTRODUCTION: The efficiency of Cambridge Cognitive Examination' (CAMCOG) is analyzed as a tool to detect dementias in epidemiological studies. PATIENTS AND METHODS: The data were obtained from subjects who enrolled the second phase on a door-to-door field epidemiological study. The tool used was the 'Cambridge Mental Disorders of the Elderly Examination' (CAMDEX). RESULTS: From the total sample of 602 subjects, 189 (31%) were men and the remaining 413 (69%) were women. The age average was 77.21 +/- 6.18 for the men group and 78.76 +/- 5.98 for the women group. The cut-off point that obtained best efficacy was 59/60. A multiple regression analysis was made using CAMCOG total scoring as the dependent variable and clinical diagnosis, age, sex and scholarship as independent variables. All the variables intermediate on CAMCOG total scoring with a multiple correlation coefficient (R) of 0.7061 (p < 0.0000). Five of the twelve CAMCOG subareas were efficient with a significance level of p > 0.0000, classifying correctly the 82.56% of the subjects. CONCLUSION: The CAMCOG is a moderate efficient total to discriminate dementia from no dementia on epidemiological studies.

Aged↗
PubMed1997

[Simulation of a decoupling generalized predictive control algorithm for temperature-humidity system].

A decoupling generalized predictive control algorithm was presented in this paper. This algorithm was proposed to control the temperature-humidity system of a practical air-conditioning environmental chamber. By introducing absolute humidity as an intermediate variable, temperature and humidity of the system can be decoupled. Then the two decoupled systems are controlled by generalized predictive control (GPC) algorithm at different sample rates. Many simulation experiments demonstrated the effectiveness of the algorithm. Besides, decoupling of temperature and humidity will be extremely helpful to the application of GPC on the real system. This is also the effective method to control the temperature and humidity system.

Air Conditioning↗
PubMed1984

Does female education affect fertility behaviour in Pakistan?

The study explores the relationship between female education and fertility in Pakistan and is based on data from the Pakistan Fertility Survey 1975. Only slight differentials were identified between women with no education and those who had primary or less schooling. However, women with more than primary education had notably lower fertility. Also the role of the intermediate variables such as proportions married, length of breastfeeding, and contraceptive use had significant associations with female education.

Age Factors↗
PubMedDate not supplied

[Approaches to low-income groups' sexuality: a comparative study of women in three low-income contexts in Peru].

"This work...examines the cultural dimension of sexuality and fertility of women from [low-income] sectors in Peru. It intends to explain the cultural processes that fall into the intermediate variables of fertility, such as marriage rate, contraception, breastfeeding and...abortion. These dimensions of sexual and reproductive life are analyzed according to two explanatory dimensions: generation and cultural context of socialization. The general hypothesis is that a cultural process of homogenization of the values and behaviors has been taking place over sexuality, in such a way that the younger generations will show similar standard behaviors and values no matter their context of socialization; in the meantime, in the older groups there will exist contextual differences in these dimensions." (SUMMARY IN ENG)

Age Factors↗
PubMed1988

An analysis of the empirical relationship between contraceptive prevalence and fertility in Bangladesh.

"This paper presents an empirical relationship between contraceptive prevalence and fertility [in Bangladesh]. It also shows how much the level of contraceptive practice is to be raised to reach a targeted level of fertility on the assumption that all other intermediate variables that influence the fertility remain constant. Regression analysis has been used to measure the relationship. A formula derived from Bongaarts's model is used to find the level of contraceptive practice required to reach a targeted fertility." Data are from a variety of sources, including four contraceptive prevalence surveys carried out between 1979 and 1985, the 1975 Bangladesh Fertility Survey, and official statistical sources.

Asia↗
PubMedDate not supplied

[Neuropsychological aspects of obsessive compulsive disorder].

INTRODUCTION AND OBJECTIVE: Neuropsychological performance in obsessive compulsive disorder (OCD) and its association with disfunctions in neuroanatomic structures and clinical symptoms of disorder has been reviewed. DEVELOPMENT: OCD symptoms and different aspects between children and adult psychopatology are presented. Briefly neurobiologic studies related with the etiology and patophisiology of OCD has been revised. This article summarizes some last studies about OCD cognitive functioning and its impairment. CONCLUSION: The more impaired cognitive functions in OCD are executive functions and visual abilities, specially non verbal memory. In addition, other studies have identified verbal memory deficits. These deficits are consistent with neurodevelopmental models, which hypothesizes that abnormalities of ventral prefrontal striatal and thalamic circuits may be involved in the etiology and patophisiology of OCD. The cognitive deficits could be functioning as a intermediate variable between neurobiological abnormalities and OCD symptoms. More studies are needed to analize the OCD cognitive impairment.

Adult↗
PubMed1992

Risk factors for severe measles.

A retrospective study on measles was carried out in 522 children admitted to the Department of Pediatrics, Sumber Waras Hospital, Jakarta during the period of January 1982-December 1986. Most of the subjects (91.1%) came from lower socio-economic levels, living in unfavorable environmental conditions in crowded housing. The predominant age group was 2-5 years; complications were observed in 82.6% and mortality in 10.3%. The most common complications and cause of deaths were bronchopneumonia (94.4%), encephalopathy (88.9%) and diarrhea (25.9%) or combinations thereof. The outcome of measles infections is determined by the presence of malnutrition and complications which is influenced by the nutritional intake, exposure, susceptibility and constitution of the patients. The household characteristics (socio-economic, socio-cultural and health facilities available) influence the above mentioned interactions through intermediate variables of nutrition (feeding pattern, food supplements), constitution, age) and treatment. Research and intervention on measles can be designed and planned based on this model of interactions.

Acute Disease↗
PubMed1988

Ego and superego alterations in borderline structures: their effect on the process and outcome of treatment.

The intermediate variable establishing the link between pathological structural alterations and aetiopathogenic factors, whether constitutional or acquired, might correspond to mental substructures derived from defensively altered and pathologically internalized object relations. Some basic postulates, connected to this central thesis, guided a brief, introductory critical review of two controversial areas in the treatment of borderline structures: (a) the relationship between mental models and developmental theories and (b) the relationship between mental models and therapeutic approaches. Since the axis of this paper centred around the limitations determined by structural alterations produced by defences, I then outlined some aspects of the treatment of a patient with severe character pathology, laying particular stress on: (a) the clinical manifestations of ego and superego alterations and their influence on the process and outcome of treatment; (b) the impediments and complications stemming from early superego precursors, with reference, in particular, to the therapeutic frame and psychoanalytic tactics; and, finally (c) the limitations and vicissitudes of the interplay of specific and diatrophic (non-specific) aspects of the analytic work in the task of promoting emotional growth.

Adult↗
PubMed1995

Elevated platelet-derived microparticle levels during unstable angina.

OBJECTIVE: To use fluorescent-activated flow cytometry coupled with activation-dependent and -independent platelet-specific monoclonal antibodies in a pilot study to assess the degree and time course of platelet activation events in patients presenting within 24 h of onset of Canadian Cardiovascular Society class 4 angina. BACKGROUND: Although activated platelets play a key role in the pathogenesis of unstable angina, the development of simple assays to quantify platelet activation events directly is lacking. METHODS: Blood samples were drawn from six unstable angina patients from the coronary care every 4 h over a 24 h period into a fixative and analyzed the following day. All patients were on acetylsalicylic acid and heparin. Comparisons were made with six healthy, medication-free volunteers. Platelets were defined by flow cytometry as positive for fluorochrome-labelled monoclonal antibody to glycoprotein Ib (AP1) and within the single intact platelet window defined by scatter characteristics. The presence of the fluorochrome-labelled activation-specific monoclonal antibody (KC4.1 for anti-P-selectin, PAC-1 for activated glycoprotein IIb/IIIa) was used to determine the percentage of activated platelets. Platelet activation-dependent microparticles were identified by gating on AP1-positive events and defining microparticles (percentage of total platelet events) as being smaller (forward size scatter) than single intact platelets. RESULTS: There was a marked, sixfold increase in microparticle generation (17 +/- 7% versus 2.8 +/- 1.4%) in the unstable angina patients (P = 0.001) compared with healthy volunteers. Further assessment of six coronary care unit patients with nonischemic cardiac disorders demonstrated a highly variable intermediate level of microparticle generation (11 +/- 7%). No differences in activated glycoprotein IIb/IIIa expression were noted for the various groups and P-selectin expression was lower in the unstable angina patients (6 +/- 2% versus 12 +/- 3%, (P = 0.007). CONCLUSIONS: This pilot study suggests that measuring circulating platelet microparticle levels is a simple yet useful parameter for the assessment of platelet activation in unstable angina compared with activation markers on intact whole platelets. Despite antiplatelet and antithrombin therapy, significant platelet activation occurred in these patients over the initial 24 h. Flow cytometry may be a useful tool in assessing the efficacy of newer therapeutic modalities.

Adult↗
PubMed1977

[Cytologic diagnosis of myxoid liposarcomas of soft tissues].

Myxoid sarcomas are characterized by the presence of branching capillaries in preparations around which lipogenesis is proceeded (unilocular and multilocular). Fat is chemically neutral. The cell content is represented by two basic kinds of cells: 1. stellate lipoblast -- a cambial element of the tumor, and 2. mature lipocyte -- a terminal stage of the differentiation of stellate lipoblast. Moreover, variable intermediate forms demonstrating the stage of lipoge nesis may be encountered. The differential diagnosis between the former and intramuscular myxoma and neurinoma (Antony B type) was made. The work is based on the analysis of 10 cases of myxoid liposarcomas.

Adult↗
PubMed1997

Risk factors and clinical outcomes between fungal and bacterial keratitis: a comparative study.

PURPOSE: Previous studies on fungal and bacterial keratitis were descriptive single case series analysis. We conducted a hospital-based retrospective study to evaluate fungal and bacterial keratitis using a case-control design to compare risk factors and clinical outcomes. METHODS: Twenty-nine cases of culture-positive fungal keratitis seen over a 5-year period were compared to 51 cases of culture-positive bacterial keratitis seen over a 21 months period. Using bacterial keratitis as the reference group, case-control odds ratios (OR) for predisposing factors and cohort relative risks (RR) for clinical outcomes associated with fungal keratitis were derived. Mantel-Haenszel adjustment procedures were used to examine the respective roles of confounding and intermediate variables. RESULTS: Compared to bacterial keratitis, fungal keratitis was significantly more likely to be associated with ocular trauma (OR = 2.69, 95% confidence interval [CI], 1.06-6.86) but significantly less likely to be associated with contact lens wear (OR = 0.16, 95% CI, 0.04-0.67) and preexisting ocular diseases (OR = 0.23, 95% CI, 0.07-0.72). Fungal keratitis was more likely to perforate than bacterial keratitis (RR = 5.28, 95% CI, 1.35-20.66) and to require penetrating keratoplasty (OR = 5.86, 95% CI, 2.06-16.69). CONCLUSIONS: Fungal keratitis appears more likely to result from ocular trauma, whereas bacterial keratitis is more likely to result from contact lens wear and pre-existing ocular diseases. Fungal keratitis is more likely than bacterial keratitis to result in perforation and require penetrating keratoplasty.

Adolescent↗