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At least 19 recordsLinked to original sources

PubMed1997

Respiratory function in shoe manufacturing workers.

A study of respiratory findings was performed on 376 female workers employed in a shoe manufacturing plant. The mean age of the workers was 32 years and the mean duration of their employment was 12 years. These workers were predominantly nonsmokers. Acute and chronic respiratory symptoms were recorded for each worker, and lung function was measured before and after the work shift. Maximum expiratory flow-volume (MEFV) curves were performed on which forced vital capacity (FVC), 1-second forced expiratory volume (FEV1), and flow rates at 50% and the last 25% (FEF50, FEF25) were measured. Significantly higher prevalences of all chronic respiratory symptoms were recorded in exposed compared to control workers; in particular, chest tightness (exposed: 44.7%; control: 0%), dyspnea (exposed: 42.6%; control: 2.0%), and rhinitis (exposed: 46.3%; control: 2.4%) were far more prevalent in workers than in controls. Among the shoe workers, there was also a high prevalence of acute symptoms that developed during the work shift, being most pronounced for nose and throat irritation (61.4%). The prevalence of acute and chronic respiratory symptoms increased with duration of employment. Statistically significant across-shift reductions were recorded for all ventilatory capacity tests for the group as a whole. In comparison to predicted, the measured ventilatory capacity parameters were significantly lower for all workers (p < 0.01). Lung function abnormalities increased with duration of employment. Environmental measurements demonstrated that benzene, fur, and synthetic fibers were found at higher than allowable maximal concentrations (Croatian standards). The data suggest that work in the shoe manufacturing industry may be responsible for the development of acute and chronic respiratory impairment.

Acute Disease↗

PubMed1981

Prognostic factors and treatment effects on survival in erythroleukemia: a retrospective study of 134 cases.

A total of 134 cases of erythroleukemia (119 from the literature and 15 of the authors' patients) were reviewed in an attempt to correlate survival with age, sex, hepatomegaly, splenomegaly, lymphadenopathy, infection, or hemorrhagic complications at initial presentation; hemoglobin (Hgb), white blood cell (WBC) count, and platelet count; percent myeloblasts in the marrow at diagnosis; and treatment regimens employed. Statistical methods included single classification analysis of variance, nonparametric analysis of variance (Kruskal-Wallis method), contingency table analysis, and correlation coefficient determination for numerical data. No significant correlation between survival and age, sex, hepatomegaly, lymphadenopathy, infection, or hemorrhagic phenomena was found. Improved survival was noted in patients without splenomegaly, and in daunorubicin-treated cases in contrast to those treated with other chemotherapeutic agents. A positive correlation between survival and initial Hgb and WBC was also noted. Erythroleukemia complicating a chronic myeloproliferative disorder had a worse prognosis than de novo erythroleukemia.

Adult↗

PubMed1996

Sensory aspects of host location in mosquitoes.

Visual, thermal and olfactory stimuli all contribute to blood meal host location in mosquitoes but olfaction is probably the dominant sensory modality used for this purpose. Much attention has been devoted to the L-lactic acid receptor because it is well characterized and because its sensitivity is a major determinant of host responsiveness in the anautogenous species Aedes aegypti. Studies employing statistical analysis of close to 500 single unit recordings and the scanning electron microscope have demonstrate that L-lactic acid-excited neurons are associated with the shortest sensilla basiconica (grooved pegs) in Ae. aegypti, Culex pipiens, Aedes atropalpus and Aedes epactius. L-Lactic acid-inhibited neurons are found in either short or long grooved pegs, depending on mosquito species. Video recording analysis, a vertical dual-chamber olfactometer and a horizontal dual-port wind tunnel olfactometer have been used to study host location behaviour and nutritional preferences in the obligately autogenous Ae. atropalpus, the facultatively autogenous Aedes bahamensis and the adult diapausing species Cx. pipiens. These behavioural studies, in conjunction with electrophysiological analysis, illustrate the ways in which the interactions between reproductive condition, developmental stage and L-lactic acid receptor sensitivity determine the nutritional choice made between blood and sugar by mosquitoes and demonstrate the role that olfactory sensitivity plays in this process.

Animals↗

PubMed1994

Testing positional behavior of malagasy lemurs: a randomization approach.

Studies of primate positional behavior have only occasionally employed statistical testing because these data sets violate the assumptions underlying most standard statistical tests. As currently practiced, both common methods of collecting data on positional behavior involve sequential observations of a limited number of individuals, leading to data sets consisting of interdependent observations. Data collected from sequential observations may not be as dependent as currently accepted; however, approaches are available to deal with such data. Some previously applied tests are discussed, and an alternative strategy, a randomization test, is demonstrated. Randomization tests are based on observed rather than theoretical distributions. Thus, they are robust when applied to data sets which do not adhere to the strict assumptions inherent in standard tests. Randomization procedures suggested by Manly ([1991] Randomization and Monte Carlo Methods in Biology [New York: Chapman and Hall]) and Edgington ([1987] Randomization Tests [New York: Marcel Dekker, Inc.]) are applied to data collected for three species of lemurs studied at Ranomafana National Park, Madagascar (Lemur fulvus, Lemur rubriventer, and Lemur variegatus). Standard chi-square tests indicate statistically significant differences between these species in nearly all aspects of locomotor, postural, and substrate use behavior. In contrast, the randomization tests showed a significant difference only in the postures used by these lemurs. Lemur variegatus uses hindlimb suspensory postures much more often than L. fulvus or L. rubriventer, and the latter species use vertical clinging more often than L. variegatus. The results from the randomization tests are considered more reliable because by using individuals rather than observations as the units compared, they limit the problem of interdependence of observations and thus provide a conservative test. The particular randomization tests used also explicitly test the proposition that individuals of a species are more similar to each other than to individuals of other species. The lack of significant results is not surprising in light of the small number of individuals studied and the great deal of variability within a species for most of the variables considered.

Animals↗

PubMed1996

Magnesium, calcium and phosphorus contents in daily food rations in primary school children: questionnaire and analytic studies.

Aims of the performed studies included working out a technique of determining representative rations on the basis of questionnaire studies on school children in Wielkopolska west region of Poland. The reconstructed representative daily food rations provided grounds for analytic studies. The studies were performed in the four seasons of the year. The studied food rations failed to cover the recommended daily intake of Mg and Ca. On the other hand, the daily intake of P transgressed the food norms. The inadequate Ca to Mg and Ca to P ratios were interpreted as deserving special concern when confronted with the market situation in Poland and as creating particular health hazards for the studied school children. The employed statistical analysis demonstrated that the suggested technique of determining representative rations may be employed in evaluation of Mg, Ca and P intake.

Adolescent↗

PubMedDate not supplied

Radionuclide angiography of the heart in coronary heart disease: where do we stand?

Regional systolic left ventricular performance after myocardial infarct was assessed from 216 radionuclide angiograms performed in 170 patients. Recording of first transit of an intravenously injected bolus of technetium-99m pertechnetate was made by a multicrystal scintillation camera at a framing rate of 20 per second. The RAO view was used and a simultaneous ECG was employed. Statistics adequate for resolving regional events were obtained by a compact bolus input and phasic summation into one representative cycle of data obtained during left ventricular passage. Emphasis was given to imaging of regional systolic left ventricular function: perimeter images of end-systole and end-diastole, regional stroke volume images and ejection fraction images were processed. New trend images were presented that reflect total systolic contraction and improve image quality: regional rate of decrease and increase images, wall motion trend images and regional mean transit time images. In 96% of the cases, correspondence was found between the electrocardiographic location of the infarct and the region of major wall motion and ejection disorder. Akinesia and/or dyskinesia were seen in 77% of the cases; a ventricular aneurysm was found in 11%. Additional areas of wall motion anomalies were shown by 70%. Image analysis, nuclear image signs and their diagnostic meaning, as well as the indications for this nontraumatic examination in coronary heart disease are discussed. Relevant information for medical or surgical therapy can be obtained from early and follow-up studies in patients with unstable, progressive angina, ischemic electrocardiographic signs and those who have had myocardial infarctions.

Cardiac Output↗

PubMed1992

Two-dimensional differential scanning calorimetry: simultaneous resolution of intrinsic protein structural energetics and ligand binding interactions by global linkage analysis.

A general theoretical development for the design and analysis of two-dimensional thermal stability surfaces of proteins is presented. The surfaces are generated from multiple excess heat capacity profiles ( vs T) obtained at varying concentrations of an interacting ligand. The energetics of both the intrinsic protein stability and the protein-ligand interaction are simultaneously resolved by employing statistical thermodynamic models in global linkage analysis. This formalism allows resolution of the intrinsic protein folding-unfolding parameters (enthalpy, entropy, and heat capacity changes) as well as the ligand interaction parameters (binding stoichiometry, enthalpy, entropy, and heat capacity changes). The theory has been applied to the case of ribonuclease A and its interaction with cytidine-2'-monophosphate. The accuracy of the thermodynamic parameters obtained by this approach compares within error with those parameters that can be obtained by direct measurements.

Binding Sites↗

PubMed1996

Applications of statistical quality control to cardiac surgery.

BACKGROUND: Although originally developed for use in manufacturing statistical quality control techniques may be applicable to other frequently performed, standardized processes. METHODS: We employed statistical quality control charts (X- s, p, and u) to analyze perioperative morbidity and mortality and length of stay in 1,131 nonemergent, isolated, primary coronary bypass operations conducted within a 17-quarter time period. RESULTS: The incidence of the most common adverse outcomes, including death, myocardial infarction, stroke, and atrial fibrillation, appeared to follow the laws of statistical fluctuation and were in statistical control. Postoperative bleeding, leg-wound infection, and the summation of total and major complications were out of statistical control in the early quarters of the study period but showed progressive improvement, as did postoperative length of stay. CONCLUSIONS: The incidence of morbidity and mortality after primary, isolated, nonemergent coronary bypass operations may be described by standard models of statistical fluctuation. Statistical quality control may be a valuable method to analyze the variability of these adverse postoperative events over time, with the ultimate goal of reducing that variability and producing better outcomes.

Coronary Artery Bypass↗

PubMed1986

The social creation of dependence, dependency ratios, and the elderly in the United States: a critical analysis.

The paper addresses critically the issue of the age/dependency ratio in the United States. It is argued that embedded in this 'objective' statistic are struggles among specific social groups and societal contradictions which only come to the fore when its assumptions, calculations and usage are explored. Through an examination of the notion of social creation of dependency, the manner in which the dependency ratio is calculated and the relationship between the socio-economic structure and the creation of dependency, it is argued that the commonly employed statistics are based on assumptions that are supportive of existing dominant social relations. This phenomenon generates a reproduction of these relations and, at the same time, circumscribes the range of solutions to the problems.

Aged↗

PubMed1994

Self-rated health: biological continuum or social discontinuity?

Correlates of self-rated health among a randomly selected sample of 1863 Australian-born women 45-55 years of age were examined in two logistic regression analyses: one comparing a self-rated health of worse than one's peers with a self-rated health the same as one's peers; and, one comparing a self-rated health of better than one's peers with a self-rated health the same as one's peers. The final model for worse health was largely a reflection of the physical experience of ill health while that for better health was a more complex construct including not only the absence of illness but also markers of sociodemographic advantage and self-image. The two models had only three variables in common. Notably, the relationship between the outcome measures and one common variable, body mass index, differed markedly. It is suggested that previous analyses of self-rated health have had their power to adequately describe correlates and determinants of health status constrained. By assuming that the various self-rated health states are part of a continuum and employing statistical methods consistent with that assumption, previous studies have been unable to demonstrate the discontinuity among such states. In particular, it is suggested that self-rated health is at least in part a reflection of social role and as there is no basis for assuming that such roles form a continuum as the use of correlation-based analyses imply, then such analyses are inappropriate.

Body Mass Index↗

PubMed1996

Factors influencing patient perceived recovery in Mexico.

The aim of this paper is twofold: first, to present empirical findings, using data drawn from a comprehensive two year study of biomedical practice and patients perceptions of treatment and recovery done in a Mexico City public hospital, identifying specific aspects of the doctor-patient relationship that impact on patient perceived recovery. Second, and flowing from the first, the objective is to consider broader theoretical issues relevant to the doctor-patient relationship, the role it plays in the healing process and in biomedical practice, especially in a developing nation such as Mexico. The paper is divided into two sections: in Section I, the problem is defined and the methodology and findings are described, employing statistical and qualitative analyses. While enormous importance has been given to the doctor-patient relationship in biomedicine, the results of the study using statistical analysis, reveal that only particular components of the physician-patient encounter significantly influence differential treatment outcomes. In Section II the significance of the findings are discussed and theoretical issues are addressed bearing on the physician-patient relationship, and patients' perceptions of treatment. To illuminate the differential perceptions of treatment outcomes by patients with non-life-threatening disorders, the concept of life's lesions is proposed.

Acute Disease↗

PubMed1992

Computerized identification of patients at high risk for hospital-acquired infection.

Surveillance for hospital-acquired infections is required in U.S. hospitals, and statistical methods have been used to predict the risk of infection. We used the HELP (Health Evaluation through Logical Processing) Hospital Information System at LDS Hospital to develop computerized methods to identify and verify hospital-acquired infections. The criteria for hospital-acquired infection are standardized and based on the guidelines of the Study of the Efficacy of Nosocomial Infection Control and the Centers for Disease Control. The computer algorithms are automatically activated when key items of information, such as microbiology results, are reported. Computer surveillance identified more hospital-acquired infections than did traditional methods and has replaced manual surveillance in our 520-bed hospital. Data on verified hospital-acquired infections are electronically transferred to a microcomputer to facilitate outbreak investigation and the generation of reports on infection rates. Recently, we used the HELP system to employ statistical methods to automatically identify high-risk patients. Patient data from more than 6000 patients were used to develop a high-risk equation. Stepwise logistic regression identified 10 risk factors for nosocomial infection. The HELP system now uses this logistic-regression equation to monitor and determine the risk status for all hospitalized patients each day. The computer notifies infection control practitioners each morning of patients who are newly classified as being at high risk. Of 605 hospital-acquired infections during a 6-month period, 472 (78%) occurred in high-risk patients, and 380 (63%) were predicted before the onset of infection. Computerized regression equations to identify patients at risk of having hospital-acquired infections can help focus prevention efforts.

Cross Infection↗

PubMed1995

Statistical analyses of electromyographic activity in spasmodic dysphonic and normal control subjects.

Heterogeneity in the quality and task sensitivity of vocal symptoms in the spasmodic dysphonia (SD) population contributes to controversy as to whether this is a single disorder or two disorders with different etiologies (neurogenic versus psychogenic). Perceptual and acoustic assessments of vocal symptoms are inadequate to resolve this controversy. However, myoelectric events are intimately proximal to the source of vocal disruption and may be informative. The present report employs statistical modeling of quantitative amplitude measures of electromyographic activity recorded from thyroarytenoid to examine neuromotor bases of vocal symptoms in SD. Consideration of perceptual ratings of the quality and task sensitivity of vocal symptoms in the context of statistical models provides support for the conclusion that the range of vocal symptoms identified as SD represents a single, neurogenic disorder.

Adult↗

PubMed1991

Traumatic cervical Brown-Sequard and Brown-Sequard-plus syndromes: the spectrum of presentations and outcomes.

Brown-Sequard syndrome (BSS) and Brown-Sequard-plus syndrome (BSPS) are characterised by asymmetrical paresis with hypalgesia more marked on the less paretic side. This study examined the clinical features of 38 patients (30 males and 8 females; mean age = 32 years) with traumatic cervical BSS or BSPS who underwent comprehensive inpatient rehabilitation. Twenty two injuries were caused by road traffic accidents, 8 by penetrating injuries, 5 by diving injuries, and 3 by other causes. After an average of 35 days in acute care and 79 days in rehabilitation, 37 patients had increased muscle strength, all 38 patients improved functional abilities, 29 patients walked independently, 34 had spontaneous bladder emptying, 36 were discharged home, and 14 were employed. Statistically significant increases (p less than 0.001) were made in modified Barthel index functional scores between admission and discharge. Patients with BSPS had a better prognosis than did those with 'pure' BSS. Patients with predominant upper limb weakness had more favourable outcomes than did those with predominant lower limb weakness. Few other potentially predictive demographic, injury, or neurological factors were associated with functional outcome. Patients with BSS or BSPS generally have a good prognosis for neurological and functional improvement.

Activities of Daily Living↗

PubMed1985

[Scientific explanation as a language and its application to psychiatry].

The concept of scientific explanation plays a crucial role in the methodological discussion within psychiatry. This article shows that since scientific explanation employs a language of its own, its syntactic, semantic, and pragmatic dimensions must therefore be analysed with the help of semiotics. The pragmatic dimension is given particular attention because, hitherto, it has been comparatively neglected in the methodological discussion within psychiatry. Furthermore, the concept of explanation is viewed as a problem sui generis and investigated, to begin with, independently of problems such as causality and teleology. By means of the problem of the ambiguity of inductive-statistical explanations, it is shown that scientific explanations which employ statistical laws without taking into consideration the pragmatic concept of the state of knowledge must necessarily come to incomplete and/or contradictory results. The state of knowledge (K) is defined as the set of propositions which are accepted as true by a person (x) at a given time (t). A more precise analysis shows that, within a given state of knowledge, an accepted proposition is generally seen as more or less probable where it can be assigned a value of credibility (B) which lies between 0 and 1. The force of an explanation, in the pragmatic-informative sense, thus consists in the fact that an explanation can increase the credibility value of an explanandum-event (E) through a presentation of particular circumstances (C) and of general laws (T) such that the following holds: BTUC(E) greater than B(E). Depending on the level of the absolute value of BTUC(E), a gradual differentiation is made with respect to the quality of pragmatic-informative explanations. The various types of explanation can be differentiated according to the type of arguments employed in the explanans of a pragmatic-informative explanation; the most important members of this family of explanations are the causal, functional, teleological, and dispositional elements. Finally, the concept of explanation is differentiated from that of understanding, another key concept in psychiatry. In this respect, it is important that the incorporation of pragmatic dimensions into scientific explanation must not be equated with the use of psychological categories; the latter are of importance solely for the concept of understanding. Furthermore, the notion is rejected that in psychiatry a higher value is to be attributed to explanation than to understanding. Rather, both concepts represent different approaches to psychiatric disorders, whereby each employs a language of its own.

Humans↗

PubMedDate not supplied

Axonal processes and neural plasticity.I: Ocular dominance columns.

We present two related computational models of ocular dominance column formation. Both address nervous system plasticity in terms of sprouting and retraction of axonal processes rather than changes in synaptic strength implied by synapse-specific Hebbian models. We employ statistical mechanics to simulate changes in the pattern of network connectivity. Our formalism uses the concept of an energy function, which we interpret as related to the levels of target-generated neurotrophins for which afferents compete. In contrast, synapse-specific Hebbian models impose synaptic normalization, for which there is little experimental evidence, in order to induce competition. Our models make many predictions which require experimental investigation. We suggest that the absence of monocular deprivation effects in the optic tectum may be due to a tendency of amphibian retinal ganglion cells to preserve the complexity of their terminal arbors. One model raises the possibility that boundaries separating columns in the mammalian cortex are poorly innervated if they have been formed by complete but asynchronous retinal activation. Both models exhibit a phase transition, suggesting a discontinuity in the transition from a binocular cortex to one possessing ocular dominance columns. Finally, our other model could account for the perpendicularity of ocular dominance columns to the boundary of the primary visual cortex while admitting of less ordered central patterns.

Animals↗

PubMed1985

The risk of low birth weight. Alternative models of neonatal mortality.

The authors examine the use of the infant's weight at birth to estimate its risk of mortality by the 28th day of life. The performance of several commonly employed statistical models is compared for the population of single births to resident South Carolina mothers in 1975-1980. A log-linear function, fitting the natural logarithm of the probability of neonatal mortality to birth weight, performs far better in this analysis than a quadratic or a logistic model or a model using the logarithm of the probability of survival. The parsimonious log-linear model also appears preferable to more complex models with additional parameters. The authors use the model in an analysis of data in two-year periods to demonstrate its value as an indicator of underlying changes in neonatal prospects and its easily interpreted parameters. The results highlight the importance of changes in neonatal mortality affecting low birth weight infants, which produce a noticeable shift in the range in which low birth weight is associated with the risk of mortality. These have proven more important in accounting for the decline in mortality rates than have changes affecting only neonates with more typical birth weights in South Carolina in 1975-1980.

Birth Certificates↗

PubMed1995

The decline and rise of the medical school applicant pool.

The authors characterize the demographic changes that transpired with the decline and rise of the medical school applicant pool over the past decade, and describe the variations in academic antecedents, attrition, and graduation rates of students matriculated during that time. Data over the ten-year cycle, derived from the AAMC's Student and Applicant Information Management System (SAIMS), were examined in the context of published education and employment statistics. The contraction and expansion of the applicant pool were related to changes in the number and pattern of undergraduate majors and to changes in the employment conditions for college-educated youth. Furthermore, a significant part of the variations in size of the applicant pool is an artifact of changes in the number of repeat applications. Matriculants' pre-medical grades and MCAT scores dropped slightly during the period of applicant decline, and rebounded as admission committees were able to exercise greater selection when the pool expanded. The attrition of medical students rose and fell during this time, but the changes were small and of little discrete influence on graduation rates during the period. The downturn and rebound in applications over the past decade appear to be more related to cycles in the employment market for college graduates than to applicants' perceptions of unfavorable/favorable conditions in medical education and practice.

College Admission Test↗