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PubMed1991

Diabetes mellitus associated with late onset congenital adrenal hyperplasia: coincidence or causality?

Diabetes mellitus and late onset congenital adrenal hyperplasia due to 11 beta-hydroxylase deficiency were observed in two female siblings aged 51 and 60 years. Not only coincidence but also causality (hyperinsulinism, glucose intolerance due to hyperandrogenism) should be considered when explaining the association of diabetes mellitus with late onset congenital adrenal hyperplasia.

Adrenal Cortex Hormones↗

PubMed1988

Conduct disorder and cognitive functioning: testing three causal hypotheses.

The sample consisted of black adolescents who were members of the Columbia-Presbyterian chapter of the Collaborative Perinatal Project from birth to age 7. At age 17, subjects and their parents were administered a battery of instruments that included standardized psychiatric diagnostic interviews as part of a call-back study. Results from least-squares and logistic regression analyses were compatible with the hypothesis that deficiencies in cognitive functioning are causally related to adolescent conduct disorder as defined by DSM III. The results suggested that the relation of cognitive functioning to psychiatric status appears to be specific to conduct disorders. The results were incompatible with a "third" variable hypothesis (third factors included neurological status and environmental disadvantage) and the hypothesis that conduct problems lead to deficits in cognitive functioning. The 3 most (and equally) important factors in accounting for age-17 conduct disorder were cognitive functioning, parent psychopathology, and early aggression. A closer look at the data tentatively suggested that a broad deficiency in acculturational learning, rather than narrowly focused social cognitive differences or native endowment, constitutes a key element in the link between cognitive functioning and conduct disorder. Test bias was ruled out as a possible explanation for the results.

Adolescent↗

PubMed1991

Two metamodels of causal effects.

Two metamodels, termed Model S and Model V, are proposed for definition, measurement, and generalization of quantitative causal effects. The effect is defined as a part change in score in Model S and as a part change in variance in Model V. Two additional changes, total and remainder change, are defined. The latter is due to all other factors or variables than the cause, while total change is the sum of remainder and effect change. Furthermore, it is shown how contrafactual concepts, which imply that some parts of the study situation are supposed to be otherwise, enter into the metamodels. Casual effects are defined and measured in terms of non-contrafactual concepts, except that statistical induction includes contrafactual as well as non-contrafactual inferences. Non-statistical generalization involves both kinds of inferences. Contrafactual definitions are considered inadequate, and a contrafactual interpretation of statistical adjustment is unnecessary and should be replaced by a non-contrafactual one.

Adult↗

PubMed2006

The complex causality of geographical parthenogenesis.

Asexual organisms usually have larger and more northern distributions than their sexual relatives. This phenomenon, called geographical parthenogenesis, has been controversially attributed to predispositions in certain taxa; advantages of polyploidy and/or hybrid origin; better colonizing abilities because of uniparental reproduction; introgression of apomixis into sexuals; niche differentiation of clones; or biotic interactions. This review on apomictic plants demonstrates that each of these factors alone has not been able to explain the observed distributions. Establishment of the complex regulatory system of apomixis requires taxonomic and geographical predispositions; hybridization and/or polyploidization do create diversity, but they do not necessarily result in large distributions; colonizing abilities depend on clonal diversity and are outweighed by sexuals by self-compatibility and higher potentials for speciation; niche differentiation, ploidy levels and selfing keep sympatric sexuals and apomicts separated; and the impact of biotic interactions on distributions is uncertain. In conclusion, the distributional success of apomicts has a complex causality and depends on certain circumstances and combinations of factors. The rare establishment of apomixis may help to explain the predominance of sexuality on the large scale.

Genotype↗

PubMed1986

Causal origins of major mental handicap in the Canadian Maritime provinces.

From a retrospective epidemiological survey, the prevalence of major mental handicap among seven- to 10-year-old children in the Maritime region of Canada in 1980 was estimated to be 36.5 per 10,000 children. Based on information obtained for 221 of the 307 children ascertained by the survey, prenatal origins dominated (58 per cent), followed by perinatal (10 per cent) and postnatal (4 per cent). No specific cause could be determined for 27 per cent of the children, but 41 per cent of this group had epilepsy and/or cerebral palsy in addition to major mental handicap. Significant differences were found in the causal spectrum between the Maritime region of Canada and regions studied in other developed countries. The results of this survey have implications for planning prevention programs, and for epidemiological surveillance and monitoring of adverse reproductive outcomes.

Birth Weight↗

PubMed1984

Lack of a causal relationship between the vasodilator effect of papaverine and cyclic AMP production in the dog basilar artery.

The effects of papaverine and isoprenaline on smooth muscle cells of the dog basilar artery were investigated using radioimmunoassay, electrophysiological and isometric tension recording methods. For comparative purposes, the actions of these drugs on the guinea-pig basilar artery were also examined. Papaverine and isoprenaline (1 microM and 10 microM) increased the amount of cyclic AMP in both dog and guinea-pig basilar arteries. Papaverine (up to 100 microM) and isoprenaline (up to 1 microM) had no effect on the membrane potential and membrane resistance measured by recording the amplitudes of the electrotonic potentials in smooth muscle cells of the dog and guinea-pig basilar arteries. The action potential evoked by outward current pulses after pretreatment with tetraethylammonium chloride (5-10 mM) was inhibited by papaverine (greater than 1 microM) but not by isoprenaline (up to 10 microM) in smooth muscle cells of the dog and guinea-pig basilar arteries. In the dog basilar artery, papaverine (greater than 1 microM) consistently inhibited the contractions evoked by excess concentrations of [K]o (greater than 20.2 mM) or 5-hydroxytryptamine (10 nM-10 microM), dose-dependently. Isoprenaline (1 microM) had only slight effects on the contraction evoked by low concentrations of 5-hydroxytryptamine (10 nM). In the Ca2+-free solution containing EGTA (2 mM), the contraction evoked by 5-hydroxytryptamine (10 microM) or caffeine (10 mM) was dose-dependently inhibited by papaverine (greater than 1 microM). However, isoprenaline (1 microM) had no effect on these contractions. These results indicate that the vasodilator actions of papaverine on the dog basilar artery are mainly due to inhibition of the voltage-dependent influx of Ca2+ and also to inhibition of the receptor-activated release of Ca2+ stored in the cell. Since isoprenaline increased the cyclic AMP to the same extent as papaverine but had no effect on the electrical and mechanical responses, the inhibitory actions of papaverine on this tissue may not be causally related to the increased levels of cyclic AMP induced by inhibition of phosphodiesterase.

Animals↗

PubMedDate not supplied

An ethnographic study of cervical cancer among women in rural Kenya: is there a folk causal model?

This article assesses knowledge, attitudes, and practices regarding cervical cancer among rural women of Kenya. One hundred and sixty women (mean age 37.9 years) who sought various health care services at Tigoni subdistrict hospital, Limuru, Kenya, were interviewed using a semistructured questionnaire. In addition, three focus group discussions (25 participants) were held, five case narratives recorded, and a free list of cervical cancer risk factors obtained from a group of 41 women respondents. All women were aged between 20 and 50 years. About 40% knew cervical cancer, although many still lack factual information. A history of sexually transmitted diseases (61.5%), multiple sexual partners (51.2%), and contraceptive use (33%) were identified as risk factors. Other factors mentioned include smoking, abortion, and poor hygiene standards. High parity, early sexual debut, and pregnancy were not readily mentioned as risk factors. We propose a folk causal model to explain the link between these factors and cervical cancer. Lack of knowledge constrains utilization of screening services offered at the clinics. Consequently, respondents support educating women as a way to tackling issues on cervical cancer. It is recommended that an integrated reproductive health program that addresses comprehensively women's health concerns be put in place.

Adult↗

PubMed2005

Causal links between brain cytokines and experimental febrile convulsions in the rat.

PURPOSE: Despite the prevalence of febrile convulsions (FCs), their pathophysiology has remained elusive. We tested the hypothesis that components of the immune response, particularly the proinflammatory cytokine interleukin-1beta (IL-1beta) and its naturally occurring antagonist interleukin-1 receptor antagonist (IL-1ra) may play a role in the genesis of FC. METHODS: Postnatal day 14 rats were treated with lipopolysaccharide (LPS; 200 microg/kg, i.p.) followed by a subconvulsant dose of kainic acid (1.75 mg/kg, i.p.). Brains were harvested at and 2 h after onset of FCs to measure brain levels of IL-1beta and IL-1ra. Separate groups of animals were given intracerebroventricular (ICV) injections of IL-1beta, or IL-1ra in an attempt to establish a causal relation between the IL-1beta/IL-1ra system and FCs. RESULTS: Animals with FCs showed increased IL-1beta in the hypothalamus and hippocampus but not in the cortex compared with noFC animals that also received LPS and kainic acid. This increase was first detected in the hippocampus at onset of FCs. No detectable difference in IL-1ra was found in brain regions examined in either group. When animals were treated with IL-1beta ICV, a dose-dependant increase was noted in the proportion of animals that experienced FCs, whereas increasing doses of IL-1ra, given to separate groups of animals, were anticonvulsant. CONCLUSIONS: Our results suggest that excessive amounts of IL-1beta may influence the genesis of FCs. This may occur by overproduction of IL-1beta, or by alteration in the IL-1beta/IL-1ra ratio in the brain after an immune challenge.

Animals↗

PubMed2006

Estimation of the causal effects on survival of two-stage nonrandomized treatment sequences for recurrent diseases.

In the treatment of cancer, patients commonly receive a variety of sequential treatments. The initial treatments administered following diagnosis can vary, as well as subsequent salvage regimens given after disease recurrence. This article considers the situation where neither initial treatments nor salvage treatments are randomized. Assuming there are no unmeasured confounders, we estimate the joint causal effects on survival of initial and salvage treatments, that is, the effects of two-stage treatment sequences. For each individual treatment sequence, we estimate the survival distribution function and the mean restricted survival time. Different treatment sequences are then compared using these estimates and their corresponding covariances. Simulation studies were conducted to evaluate the performance of the methods, including their sensitivity to the violation of the assumption of no unmeasured confounders. The methods are illustrated by a retrospective study of patients with soft tissue sarcoma, which motivated this research.

Analysis of Variance↗

PubMed2000

Characterization of an amylase produced by a Trichoderma harzianum isolate with antagonistic activity against Crinipellis perniciosa, the causal agent of witches' broom of cocoa.

An isolate of Trichoderma harzianum showing antagonistic activity against Crinipellis perniciosa, the causal agent of the witches' broom disease of cocoa, produces substantial amounts of hydrolytic enzymes. An amylase purified from isolate 1051 had a molecular mass of about 68.7 kDa. Maximal activity against soluble starch was determined at pH 4.0 and 60 degrees C. The K(m) and V(max) values were 3.5 mg ml(-1) and 1.67 mg min(-1) of reducing sugar. The end products were mostly malto-oligosaccharides. The enzyme also hydrolyzed glycogen, amylopectin, maltotriose, and maltotetraose, but not pullulan or cellobiose. Maltose was only barely hydrolyzed. The purified amylase exerted a discrete hydrolytic effect on the C. perniciosa cell wall in vitro as observed by scanning electron microscopic analysis. While Fe(3+), Al(3+), Zn(2+), and Cu(2+) were effective in inhibiting the purified amylase, Mn(2+) considerably enhanced the activity. Ca(2+), Mg(2+), and Co(2+) showed no substantial effect on enzyme activity.

Amylases↗

PubMed1994

A latent variable causal model of the quality of life and community tenure of psychotic patients.

Services are intended to maintain patients in the community while improving the quality of their lives. The purpose of this study was to determine the extent to which psychiatric patients' diagnoses, levels of autonomy, objective living conditions and degree of service utilization are associated with their perceived quality of life and, in turn, community tenure. A latent variable causal model was developed and tested using data from 152 schizophrenic and affective psychotic patients. Information was obtained using a semistructured interview, a quality of life scale, ratings on the Global Assessment Scale and patient hospital records. Results indicate that greater autonomy is significantly associated with greater perceived quality of life and that greater quality-of-life ratings are associated with greater community tenure.

Activities of Daily Living↗

PubMed1982

Causal analysis on the use of dental services among old-age pensioners in Norway.

The purpose of the present paper was to establish and evaluate a causal model on the use of dental services in Norwegian old-age pensioners living at home. Data were derived from the Health Survey of 1975. The independent variables sex, age, education and dental status were dichotomized and arranged in this assumed temporal sequence. The dependent variable was also dichotomized into use versus non-use of dental services last year. The analysis started with the bivariate percentage table for sex and use, and then proceeded by adding one by one of the independent variables in the order of their time sequence. In this way the statistical relationship between an independent and the dependent variable was decomposed into direct, indirect and spurious effects. Dental status was the most influential determinant of use of services, having the greatest direct effect (0.40) and mediating indirect effect of the prior variables. Education came second with a direct effect of 0.18 and an indirect effect (0.11) by affecting dental status. There were only negligible differences in use rates between the age groups (less than 75 / greater than or equal to 75 years of age) when the other variables were held constant (0.05, P greater than 0.05). The greater part of the direct effect of sex (0.11) was limited to dentate persons aged 65-74 with low education. Both age and sex affected use of services indirectly through dental status (0.09 and --0.04, respectively).

Age Factors↗

PubMed1976

Tissue hyperosmolality as a causal factor in vasodilatation following sympathetic stimulation of the submandibular gland.

In a previous investigation, parasympathetic activation of the submandibular gland in the cat was found to cause a considerable increase of regional tissue osmolality, the degree of which was related to the evoked functional hyperemia; intra-arterial hypertonic infusion to the resting gland producing tissue hyperosmolality of similar magnitudes caused graded and marked dilatations (Lundvall and Holmberg 1974). It was concluded that hyperosmolality contributes significantly to the functional hyperemia response. In the present study evidence is presented to indicate that tissue hyperosmolality is a mediator of the dilatation associated with sympathetic activation as well. An increase of tissue hyperosmolality, as traced in the venous effluent, was found at all frequencies of sympathetic stimulation (2-16 Hz). At high stimulation rates it sometimes exceeded the resting control level by more than 20 mOsm/kg H2O. There was a direct relation between the degree of venous hyperosmolality and the hyperemia response observed immediately after cessation of stimulation. Comparison of the dilator effects evoked by sympathetic stimulation and by hypertonic infusion to the resting gland indicated that tissue hyperosmolality is an important causal factor for the nerve induced dilatation, especially at low and moderate stimulation rates.

Animals↗

PubMed1999

Plasma homocysteine as a cardiovascular risk factor: causal, consequential, or of no consequence?

Elevated plasma total homocysteine may be causally related to the risk of atherosclerotic cardio-vascular diseases. Many significant studies indicate an effect by elevated homocysteine on cardiovascular disease occurrence, progression, and recurrence that is independent of traditional risk factors. However, recent data have cast doubt on the veracity of the relationship between elevated plasma total homocysteine and the incidence of cardiovascular disease. In general, a stronger relationship has been found in cross-sectional and retrospective case-control studies than in nested case-control or prospective studies. The issues of study design, bias, and confounding are critical to an analysis of this putative relationship, and their effects can only be avoided by randomized controlled trials of homocysteine-lowering therapy (folic acid). While awaiting the outcome of these trials, there may already be sufficient evidence to prescribe homocysteine-lowering therapy in subjects deemed to be at high risk of cardiovascular disease.

Aged↗

PubMed1979

The effects of congenital heart disease on cognitive development, illness causality concepts, and vulnerability.

This study suggests that childhood cardiac illness has a depressive impact on the attainment of conservation tasks, but does not affect illness causality conceptualization. The group of twelve ill children studied appeared to feel somewhat more vulnerable to illness in general, especially when projecting to adult health status, than did a matched group of healthy children.

Adaptation, Psychological↗

PubMed1988

Causal beliefs amongst families in therapy: attributions at the group level.

Whereas attribution has traditionally been regarded as an individual process, we argue that attributions can also be located at a group level. A study of the causal beliefs of 10 families undergoing family therapy is reported, which shows that attributional change can be identified as a family as well as an individual process. Families considered not to have 'changed' following therapy differed from the 'changing' families in attributing negative outcomes to more stable causes, but were similar in their increased use of internal attributions for other people's actions. This pattern is interpreted within family systems theory.

Adolescent↗

PubMed1992

Staff attitudes towards patients: the influence of causal attributions for illness.

The aim of this study is to determine whether staff attitudes towards patients are affected by staff causal attributions. Forty-eight nurses and doctors were presented with five case histories of patients suffering from lung cancer, liver cirrhosis myocardial infarction, breast lump and cervical cancer. There were two versions of each case: one patient had followed and the other had ignored a relevant health action (e.g. not smoking in the lung cancer patients). Subjects responded to just one version of each case. For all five conditions, staff had significantly more negative attitudes towards patients who had not undertaken a relevant health behaviour compared with patients who had undertaken a relevant health behaviour. A second group of nurses rated it as more likely that this latter group of patients could have prevented their illnesses. The results suggest that information about a patient's health habits prior to illness influence staff attitudes to that patient. Evidence is presented suggesting that the effect of this information is mediated by perceived controllability of the illness, as predicted by an attributional model of helping behaviour.

Attitude of Health Personnel↗

PubMed1994

Perceived locus of causality, goal orientations, and perceived competence in school physical education classes.

Ryan & Connell (1989) have demonstrated that different types of behavioural regulation can be located on a continuum of perceived autonomy or perceived locus of causality. The present study applied their formulation in the context of school physical education (PE) and examined the relationships of perceived autonomy, perceived competence and goal orientations with intrinsic interest across two PE activities. School students aged 12-14 years (N = 85) completed an adapted version of the Self-Regulation Questionnaire (Ryan & Connell, 1989) and measures of perceived competence and intrinsic interest separately for two PE activities. They also completed the British version of the Task and Ego Orientation in Sport Questionnaire (Duda, Fox, Biddle & Armstrong, 1992). Students appeared to be differentially motivated for the two activities due to different perceptions of autonomy. Structural equation modelling analysis showed that perceived autonomy and task orientation had direct effects on intrinsic interest for both the activities. Perceived competence, however, was positively associated with intrinsic interest only for one of the activities. The implications of the results for the practice of physical education are discussed.

Achievement↗