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The author presents 12 theories which try to evaluate the significance of paranasal sinuses. A vast amount of references on this subject and additionally this paper do not explain the role of paranasal sinuses in human. In the author's opinion the most probable is the amortizative and constructive theory based on antropometric studies and experimental head traumas.
Thermodynamic theory of aging explains changes of the functions of states of cells and tissues during aging. The rates of aging depend on the genetic factors, the nature of habitat, nutrition and external influences. These rates can be different. Aging of organs, functional systems and tissues, as theirs diseases, lead decrease of adaptational ability of organism and its death.
This paper gives an overview of the kaupapa and processes of a Maori health research unit and it's researchers within the university environment. It begins with an understanding that research is often viewed with suspicion by Maori, is implicated in the process of colonisation and that Maori research has, in part, grown out of dissatisfaction with prevailing methodologies. Unfortunately this has also involved confronting the argument that there is no such thing as kaupapa maori research. Defining kaupapa maori research is therefore not a comfortable exercise. The need to define, discuss or explain its existence in itself serves as a reminder of the power of colonisation. Kaupapa maori begins as a challenge to accepted norms and assumptions about knowledge and the way it is constructed and continues as a search for understanding within a Maori worldview. If kaupapa maori is about taking for granted a Maori worldview, then this discourse in itself subverts our right to be maori-ordinary. We are now the other in our own country. While kaupapa maori research may be seen as taking a distinctive approach and having underlying principles or aspects which are based on this Maori worldview, methods are likely to be subordinate to the issues and utility of the research and may be drawn from a range of methodologies. By taking a position that challenges norms and assumptions, kaupapa maori research involves a concept of the possibility and desirability of change. The research should aim to make a positive difference (Smith, 1999) and therefore the use, usefulness and ownership of the research are of paramount importance.
During the 1990's the international variation in the prevalence of asthma and allergy was studied in young adults (European Community Respiratory Health Survey, ECRHS) and in children (International Study of Asthma and Allergy in Children, ISAAC). The prevalence of asthma and allergy was highest in the United Kingdom, North America, Australia and New Zealand, lower in the Baltic countries and very low in some of the poorest republics of the former USSR. Children that lived in the countryside during the first year of life had a lower prevalence of atopic disease as teenager while in adults farmers had the highest prevalence of occupational asthma. In both investigations a negative association was found between having pets as a child and atopic sensitisation. This association could, however, be related to selection mechanisms. In a three year follow-up of the Swedish part of the ECRHS the incidence of asthma was higher in smokers than non-smokers. Passive smoking was associated with respiratory symptoms in both children and adults. Follow-ups of both studies are being planned or performed. Further analyses of the geographic differences may explain the reason for the rapid increase of asthma and allergy in the Western world.
This study proposes a model explaining the association between physical abuse of children and children's social and affective status as one in which children's social expectations and behavior, developed within the context of abusive parenting, mediate current functioning in these two outcome domains. Subjects included one hundred 9 to 12-year-old physically abused children recruited from consecutive entries onto the New York State Register for Child Abuse for New York City and 100 case-matched classmate nonabused comparison children. Sociometric assessments were carried out in classrooms, interviews were conducted with the children and their parents, and teachers, parents, and classmates rated the children's behavior. Path analysis was utilized to test the conceptually derived models. Children's social expectations regarding peers, and two social behaviors--aggressive behavior and prosocial behavior--were found to mediate between abuse and positive and negative social status, as well as between abuse and positive and negative reciprocity. Social expectations and withdrawn behavior mediated between abuse and positive social status, but only where withdrawn behavior was a function of social expectations. Social expectations were generally found to mediate between abuse and internalizing problems. Negative social status (peer rejection) added to social expectations in producing internalizing problems. Identification of these mediating pathways can serve to guide secondary preventive intervention efforts so that they best address the problems abused children face in the absence of adequate parental and peer support as the children enter adolescence.
BACKGROUND: The proportion of patients admitted involuntarily varies considerably among Norwegian psychiatric hospitals. We tested the hypothesis that these variations are the result of differences in case-mix. MATERIAL AND METHODS: The observed differences in involuntary admissions to Norwegian psychiatric hospitals were compared to those expected on the basis of their case-mix, as predicted by our multivariate model (multinomial logistic regression). The material was based on a cross-sectional registration of hospitalized patients in Norwegian psychiatric hospitals as of 1 November 1999. Thirty-two hospitals (all Norwegian hospitals that take involuntary admissions) supplied data on a total of 1,500 patients. RESULTS: The analysis shows that a large amount of the observed variation in involuntary admissions is related to differences in case-mix. However, for patients involuntarily admitted for observation, the case-mix was found to have less explanatory effect. Age, sex, previous admissions and diagnoses were used to operationalize hospital case-mix. INTERPRETATION: The analysis also indicated that other explanatory factors should be explored, such as differences in admission threshold and in medical decision in explaining variation in involuntary psychiatric admissions.
This article explains divergent reports on the relative efficacy of unilateral and bilateral electroconvulsive therapy (ECT) by hypothesizing a therapeutic effect of both seizure and electrical stimulus, with the seizure's effect based on its intensity and generalization. The effect of the stimulus is normally obscured by the seizure but emerges with reduced electrical dosage or elevated threshold. These circumstances favor a therapeutic advantage for bilateral ECT, which introduces more electrical charge into a larger and differently distributed volume of brain and induces greater seizure generalization, more diencephalic stimulation, and a relative decrease in left relative to right hemisphere electroencephalographic (EEG) frequencies.
The authors examined whether hostility explained the discrepancy commonly observed between clinic and daytime ambulatory blood pressures. Daytime ambulatory blood pressure (DABP) was assessed every 45 min over 6 days in healthy adults (N = 120). After controlling for demographic variables, time-varying covariates such as position and activity level, and clinic blood pressure (CBP), the Cook-Medley Hostility Scale was significantly associated with daytime ambulatory diastolic blood pressure. No support was obtained for mediation by psychological factors. Discrepancies between DABP and CBP may be due, in part, to differences in the degree to which these 2 types of measures are associated with individual differences in hostility. These results suggest that the addition of hostility to CBP may improve its predictive power.
Several case-control studies agree that elevated homocysteinemia (HC) is a risk factor for cardiovascular disease, particularly for acute myocardial infarction (AMI). However, this agreement does not extend to prospective studies--some of which confirm and others (MRFIT and Karelia) reject this relation. After an AMI there are significant changes in biochemical and laboratory parameters, including a decrease in cholesterolemia, which takes several months to return to baseline levels. The evolution of HC after AMI is still unknown. In this work we set out to evaluate the evolution of homocysteinemia values after acute myocardial infarction. We evaluated fasting homocysteinemia in 34 sequential patients after admission to the Intensive Care Unit and after confirmation of acute myocardial infarction (26 male; mean age 63.8 +/- 13.9 years) in the first 36 hours, between the 3rd and 6th day, and one month after AMI. Simultaneously, we studied traditional risk factors and performed routine laboratory tests. The mean values found for HC were 13.85 +/- 5.46 mol/l in the first 36 hours after AMI, 16.16 +/- 6.63 mol/l between the 3rd and the 6th day, and 16.27 +/- 7.27 mol/l one month after myocardial infarction. The difference between the first and the second, and between the first and the third measurements, was significant (p < 0.05). The HC values found 3-6 days and one month after myocardial infarction were similar (p = 0.88). A highly significant correlation was found between HC values assessed in the first and second (correlation coefficient [CC] = 0.62) and in the second and third measurements (CC = 0.57), both with p = 0.001. We can conclude that HC levels increase significantly 36 hours after an acute myocardial infarction, an increase of around 20%, which is maintained until at least one month after the infarction. In these circumstances the difference in the vascular risk of HC found between case-control and prospective studies may be explained, at least partially, by the HC increase after AMI.
BACKGROUND: Fee-for-item payments are the main source of remuneration for primary care physicians in Norway. Physicians receive a major part of these payments from the National Insurance Administration. The present study describes the development in the National Insurance Administration expenditure for primary physician services in Norway from 1990 to 2000. MATERIAL AND METHODS: The analyses were performed on accounting data from the National Insurance Administration and data on the number of physician per 10,000 population from Statistics Norway. RESULTS: From 1990 to 2000, expenditure increased by 84%, from NOK 863.8 million to NOK 1.58 billion. Our main finding is that a substantial part of this increase can be explained by increases in the number of primary care physicians, population size, and the level of fees. INTERPRETATION: One interpretation of our findings is that National Insurance Administration expenditure on primary physician services to some extent can be controlled by regulating the number of physicians practicing with reimbursement from the National Insurance Administration and the level of fees.
BACKGROUND: In a quantitative overview of published trials, we investigated whether some pharmacological properties of antihypertensive drugs, besides reduction in blood pressure, explain cardiovascular outcomes in hypertensive or high-risk patients. METHODS: Across trials, using meta-regression, we correlated odds ratios with differences in systolic blood pressure between study groups. We then compared odds ratios of benefit observed in recent trials with those predicted by metaregression on the basis of the differences in systolic pressure between randomised groups. RESULTS: Significant differences in systolic pressure between randomised groups (experimental minus reference) were observed in the ALLHAT (-2/+1), CAPPP(-3/-1) and NORDIL (-3.1/+0.2) trials. Furthermore, the differences in achieved systolic and/or diastolic pressure between study groups were also significant in the hypertension trials which involved untreated control patients, as well as in MIDAS (-3.5/ approximately 0 mm Hg), HOPE (-3.3/-1.0 mm Hg), PART2 (-5/-4 mm Hg), and SCAT (4/-2 mm Hg) (1). The differences between the observed odds ratios and those predicted by the meta-regression between outcome and difference in systolic pressure did not reach statistical significance except for the NORDIL trial, in which the risk of stroke was lower on diltiazem than on the older drugs despite a 3.1 mm Hg higher systolic pressure on the calcium-channel blocker. CONCLUSIONS: The finding that in the reviewed trials blood pressure reduction largely accounted for outcome emphasizes the desirability of blood pressure control. The hypothesis that converting-enzyme inhibitors or alpha-blockers might influence cardiovascular prognosis over and beyond their antihypertensive effect remains unproved.
The interrelationships between macro and micro factors in the analysis of interstate migration in the United States are explored. A synthesis between these factors is attempted "by combining objectively calibrated characteristics of states with their subjectively measured counterparts....First, the relationships between the objective variables and their subjective counterparts are analyzed. Second, both sets of variables are used to explain residential preferences and migration. Third, a series of path models are constructed to indicate how the subjective variables act as intervening variables between their objective counterparts and migration."
"There has recently been some speculation that the physical location of a community on the coast plays an equal or even more important role than does region in terms of the importance of geography upon population growth. This paper explores in empirical fashion the relative importance of coastal siting, as well as location, in the South or West, along with variables measuring economic base and demographic structure in explaining the relative rates of population growth in American metropolitan areas from 1980 to 1990."
"Prior research on immigrant naturalization has focused mainly on the effects of immigrants' adaptation experiences and demographic characteristics on their propensity to naturalize. This article proposes a broader analytical framework which incorporates immigrants' individual characteristics and larger social contexts in the country of origin and the country of destination to explain the likelihood of citizenship acquisition. The framework is tested for a cohort of recent immigrants, using the PUMS data from the 1980 U.S. census. The results show that economic, political, social, cultural and geographical conditions in the country of origin, and immigrants ethnic communities and urban concentration in the country of destination, to a large extent influence immigrants' propensity for naturalization and that, net of the contextual factors, many of the immigrants' adaptation and demographic characteristics are also significant predictors of citizenship acquisition."
Carriership of the factor V (FV) R2 haplotype is associated with mild APC-resistance, moderately reduced FV levels and a relative increase of the more thrombogenic FV isoform, FV1. Since low FV levels and increased FV1 can theoretically cause APC-resistance, we investigated whether these alterations can quantitatively account for R2-associated APC-resistance. In order to determine the effect of FV concentration and FV isoform composition on the APC-response, we reconstituted FV-deficient plasma with purified FV1 and FV2 in different molar ratios and to varying FV concentrations. APC sensitivity ratios (APCsr) were determined with the Coatest APC Resistance V, which probes the effect of APC on both FVa- and FVIIIa-inactivation, and with the Immunochrom APC response test, which only quantifies the effect of APC on FVIII(a)-inactivation. In both assays, low FV concentrations and/or high relative amounts of FV1 rendered plasma samples more resistant to APC. APCsr were also determined in FV-deficient plasma reconstituted with purified FV at levels and isoform ratios observed in R2-homozygotes (98% FV, 42% FV1) and age-matched controls (119% FV, 26% FV1). In both tests the APCsr of reconstituted control plasma was the same as that of plasma from controls, whereas reconstituted R2-plasma was less APC-resistant than plasma from homozygous carriers of the R2 haplotype. We conclude that the low FV levels and altered FV isoform ratio cannot fully explain R2-associated APC-resistance.
Several lineages have independently evolved from isogamy (all sexes producing similar gametes) through anisogamy (dissimilar gametes) to the familiar male (producing sperm) and female (producing eggs) condition of most large, multicellular organisms (oogamy). A variety of hypotheses explaining the selective mechanisms causing such evolution and the success of these lineages have been proposed, but little evidence and some confusion persists. Here, a few simplifying assumptions are used to extract and compare the essential features of the various ecological hypotheses. The comparisons reveal that the critical need is to identify a selective advantage of large, immobile gametes (eggs). Assumptions about the effect of sperm size on swimming speed are not important. The classic assumption of increasing zygote success with large size requires a relationship even stronger than survival proportional to volume, which seems unlikely and lacks empirical support. An assumption that eggs produce a pheromone sperm attractant leads, by established physical principles, to a more than sufficient advantage of large egg size. Without pheromones, combinations of increased target size and weaker increased zygote fitness or increased gamete longevity also provide sufficient selection.
BACKGROUND: Socioeconomic status appears to be an important predictor of coronary angiography use after acute myocardial infarction. One potential explanation for this is that patients with lower socioeconomic status live in neighbourhoods near nonteaching hospitals that have no catheterization capacity, few specialists and lower volumes of patients with acute myocardial infarction. This study was conducted to determine whether the impact of socioeconomic status on angiography use would be lessened by considering variations in the supply of services. METHODS: We examined payment claims for physician services, hospital discharge abstracts and vital status data for 47 036 patients with acute myocardial infarction admitted to hospitals in Ontario between April 1994 and March 1997. Neighbourhood income of each patient was obtained from Canada's 1996 census. Using multivariate hierarchical logistic regression and adjusting for baseline patient and physician factors, we examined the interaction among hospital and regional characteristics, socioeconomic status and angiography use in the first 90 days after admission to hospital for acute myocardial infarction. RESULTS: Within each hospital and geographic subgroup, crude rates of angiography rose progressively with increases in neighbourhood income. After adjusting for sociodemographic, clinical and physician characteristics, hospitals with on-site angiography capacity (adjusted odds ratio [OR] 1.88, 95% confidence interval [CI] 1.52-2.33), those with university affiliations (adjusted OR 1.60, 95% CI 1.27-2.01) and those closest to tertiary institutions (adjusted OR 1.57, 95% CI 1.32-1.87) were all associated with higher 90-day angiography use after acute myocardial infarction. However, the relative impact of socioeconomic status on 90-day angiography use was similar whether or not hospitals had on-site procedural capacity (interaction term p = 0.68), had university affiliations (interaction term p = 0.99), were near tertiary facilities (interaction term p = 0.67) or were in rural or urban regions (interaction term p = 0.90). INTERPRETATION: Socioeconomic status was as important a predictor of angiography use in hospitals with ready access to cardiac catheterization facilities as it was in those without. The socioeconomic gradient in the use of angiography after acute myocardial infarction cannot be explained by the distribution of specialists or tertiary hospitals.
There are three hypotheses to explain the relation between allergens and other factors and the onset of atopy: the hygiene hypothesis, the TH2 like hypothesis and the allergenic hypothesis. None of them have been confirmed. It seems necessary to wait for the results of prospective studies before giving recommendations for primary prevention of respiratory allergic diseases. In contrast, tertiary prevention appears as an essential method for treatment of allergic diseases.