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PubMed1988

T lymphocyte development and maturation in horses.

Monoclonal antibodies specific for equine T lymphocyte subpopulations were produced and procedures for the continuous culture of equine lymphocytes were developed. These reagents and procedures were used to analyse the appearance, maturation and functions of T lymphocytes in normal horses and in T lymphocyte deficient horses with severe combined immunodeficiency (SCID). T lymphocytes appeared as early as the 75th day of fetal development and were normally distributed prior to birth of normal foals. Analysis of thymic T lymphocyte differentiation in SCID foals revealed the presence of both prothymocytes and mature thymocytes, but a virtual absence of cortical thymocytes. The data obtained support the hypothesis that two distinct pathways of T lymphocyte differentiation exist within the thymus. Although the gene defect in foals with SCID blocks the production of mature B and T lymphocytes, such foals do possess large granular lymphocytes which are cytotoxic following induction with interleukin 2. This suggests that lymphoid cells with natural killer cell activity are spared by the gene defect resulting in SCID in horses.

Animals↗

PubMed1979

Evaluation of the activated whole blood clotting time (ACT) in vitro.

The activated whole blood clotting time (ACT) was analyzed in vitro using blood samples from normal individuals and from patients with heart disease, scheduled for open heart surgery. The ACT was found to be normally distributed in a group of normal individuals with a mean of 135 sec. In patients with heart diseases, the average ACT was slightly shorter than in normal individuals. A linear relationship between ACT and heparin concentrations was established. Haemodilution and depletion of platelets did not significantly influence the ACT. When a clean venipuncture with disposable needles is used, ACT is a reliable, uncomplicated bedside technique by which heparinisation can be monitored.

Blood Coagulation Tests↗

PubMed1976

Permeability of individual human erythrocytes to thiourea.

The osmotic swelling to haemolysis of individual red blood cells by isosmotic thiourea has been studied using microcine photography. 2. Crenation occurs immediately upon addition of isosmotic thiourea. The cell becomes a crenated sphere without volume decrease. 3. Subsequently, the cell volume increases linearly with time with maximum swelling occurring at about 102 sec which is 81% of the total haemolysis time. 4. At maximum swelling, the cell volume is 92% greater than the initial cell volume. This volume increase is about double that measured with other permeating substances. 5. The much larger maximum volume implies that thiourea increases the area of the cell membrane. This increase varies from 0 to 75% for individual cells, with a mean of 22%. 6. Membrane expansion varies inversely as the initial cell membrane area and cell volume (r=0-790). 7. Using the increased surface area, increased maximum volume and the swelling time, the mean permeability is calculated to be 5-52 X 10(-7) cm/sec (S.D. of mean=+/-1-19 X 10(-7) cm/sec). The distribution of permeabilities represents a normal distribution. 8. The pre-lytic potassium loss ranged from 0 to 36% with a mean value of 16-5%. This is consistent with values reported in the literature for slow haemolysis. As with other permeants the distribution is skewed towards lower values. 9. Membrane permeability of individual cells varies with the amount of membrane expansion observed. Coefficient of correlation between permeability and expansion index is 0-674. 10. There is no correlation between permeability and the reciprocal of the haemolysis time (r=-0-035). The correlation between permeability and the reciprocal of the swelling time is also poor (r=0-303), probably owing to the variability in membrane expansion by thiourea in individual cells. 11. As has been shown previously for faster permeants, the permeability coefficient cannot be calculated from the haemolysis time. Because thiourea alters the membrane area and the haemolytic volume, the coefficient cannot be calculated from the swelling time unless the changes in the membrane area are also taken into account.

Cell Membrane↗

PubMed1985

Lymphocyte fluctuation in bronchoalveolar lavage fluid in normal volunteers.

In an attempt to understand the widely varying bronchoalveolar lavage lymphocyte counts reported in normal subjects, we performed bronchoalveolar lavage in 42 healthy nonsmokers. The mean (SD) lymphocyte percentage in this first lavage was 9.6% (7.7%). The values did not fit a normal distribution. Five subjects had more than 20% of lymphocytes, and when they were excluded the distribution of lymphocyte counts was normal. Bronchoalveolar lavage was repeated once or twice in these five subjects 47 days or more after the previous lavage and the lymphocyte count decreased below 14% in four. Eight volunteers with an initial lymphocyte percentage less than 20% also had repeat lavages; two presented a transient increase of lymphocyte count above 20%. These data show that the percentage of lymphocytes in lavage fluid fluctuates significantly in normal subjects and suggest that lymphocyte counts counts higher than 14% should not be considered as normal.

Adult↗

PubMed1989

Distribution of sodium-lithium countertransport and blood pressure in Caucasians five to eighty-nine years of age.

Case-control studies suggest that increased erythrocyte sodium-lithium countertransport may predict increased susceptibility to the development of essential hypertension. To characterize interindividual variation in sodium-lithium countertransport and its relation to blood pressure levels in the general population, we studied 1,475 Caucasians between 5 and 89 years of age (711 males and 764 females) ascertained through 266 households with children in the schools of Rochester, Minnesota. Individuals who were taking antihypertensive agents or combinations of estrogen and progesterone were not included in the sample. A third-order polynomial regression on age accounted for only a small fraction of variability in sodium-lithium countertransport (2.8% in males, p less than 0.001; 2.1% in females, p less than 0.01), whereas a fourth-order regression on age accounted for a large proportion of variability in systolic blood pressure (45.7% in males, p less than 0.001; 52.5% in females, p less than 0.001) and diastolic blood pressure (39.8% in males, p less than 0.001; 33.0% in females, p less than 0.001). Mean sodium-lithium countertransport was higher in males than females at all ages; but the rank order of male and female means for systolic and diastolic blood pressure was age dependent. Positively skewed distributions for age-, height-, and weight-adjusted sodium-lithium countertransport in male and female cohorts between 5-19.9, 20-49.9, and 50-89.9 years of age were explained significantly better by postulating a mixture of two partially overlapping sodium-lithium countertransport distributions rather than a single normal distribution (p less than 0.01). Among men in the 20-49.9-year-old cohort, adjusted sodium-lithium countertransport values in the upper distribution were associated with higher systolic and diastolic blood pressure (mean +/- SD) than values in the lower distribution (for systolic blood pressure: 115 +/- 11 vs. 111 +/- 11 mm Hg, p less than 0.07; for diastolic blood pressure: 71.2 +/- 8.0 vs. 68.4 +/- 8.6 mm Hg, p less than 0.08). Among females in the 50-89.9-year-old cohort, adjusted sodium-lithium countertransport values in the upper distribution were associated with significantly greater diastolic blood pressure than values in the lower distribution (77 +/- 10 vs. 70 +/- 9 mm Hg, p less than 0.03).(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

PubMedDate not supplied

Lymphocyte morphology in mucoid middle ear effusions.

Cytologically, the mucoid middle ear effusions could be divided into a lymphocyte-monocyte type and a type where the granulocytes predominated. By alpha-naphthyl-acetate esterase (ANAE) staining procedure the T lymphocytes were found to make up the majority of lymphocytes in the first type, often accompanied by large numbers of ANAE-positive macrophages. In the second type the relative and particularly the absolute numbers of T cells were smaller. The T lymphocytes in aural effusions, distributed in agreement with their normal distribution in blood, could be the basis of possible delayed hypersensitivity immune mechanisms in the middle ear, but definite proof, either demonstrating receptor molecules directed to antigens or a specific response by T cells, is still lacking.

Child↗

PubMed1995

Defining and classifying learning disabilities and attention-deficit/hyperactivity disorder.

This paper provides an overview of current conceptualizations of learning disabilities and ADHD, a conceptual framework critical for defining and classifying each disorder and for distinguishing each disorder from the other and from other, less common problems of childhood. At a most basic level, reading disability or dyslexia (the most common and best defined of the learning disabilities) and ADHD represent two distinct disorders that may frequently cooccur in the same unfortunate child but that can be clearly distinguished from one another. Reading disability represents a disorder of cognitive functioning. In contrast, ADHD is defined by the child's behavior as perceived by the child's parents and teachers; ADHD thus refers to a disorder affecting primarily the behavioral domain. Within the last decade, considerable progress has been made in our understanding of reading and reading disability. Converging evidence from several lines of investigation now indicates that reading ability conforms to a normal distribution model, so that there is a continuum of reading ability and reading disability. Children along this continuum differ by degree but not in kind. Cutoff points may be instituted to segment this continuous distribution, but these will be arbitrary and will not reflect any natural joints in nature; there is no second mode or "hump" in the distribution of reading ability. The normal model of reading and reading disability indicates that reading disability is related to normal reading ability, that there is a seamless transition from good to poor reading ability. Awareness of this relationship is critical to our approach to understanding the basis of reading disability.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed2006

On the generalized poisson regression mixture model for mapping quantitative trait loci with count data.

Statistical methods for mapping quantitative trait loci (QTL) have been extensively studied. While most existing methods assume normal distribution of the phenotype, the normality assumption could be easily violated when phenotypes are measured in counts. One natural choice to deal with count traits is to apply the classical Poisson regression model. However, conditional on covariates, the Poisson assumption of mean-variance equality may not be valid when data are potentially under- or overdispersed. In this article, we propose an interval-mapping approach for phenotypes measured in counts. We model the effects of QTL through a generalized Poisson regression model and develop efficient likelihood-based inference procedures. This approach, implemented with the EM algorithm, allows for a genomewide scan for the existence of QTL throughout the entire genome. The performance of the proposed method is evaluated through extensive simulation studies along with comparisons with existing approaches such as the Poisson regression and the generalized estimating equation approach. An application to a rice tiller number data set is given. Our approach provides a standard procedure for mapping QTL involved in the genetic control of complex traits measured in counts.

Algorithms↗

PubMed2003

Factors influencing variability and potential uptake routes of heavy metals in black kites exposed to emissions from a solid-waste incinerator.

Exposure to heavy metals from emissions of the solid-waste incinerator (SWI) of Madrid (Spain) was assessed by determining the relationships between the distance from black kite (Milvus migrans) nests to the SWI and metal concentrations in nestling blood and failed eggs. Lead levels increased as the distance to the SWI decreased, while no significant relationship was found for the remaining elements. Analysis of frequency distributions showed that Pb was normally distributed, suggesting a generalized exposure to this contaminant. Variability in metal levels within and between nests indicated a differential nest exposure to contaminant metals with sibling chicks showing similar metal levels. Correlations between essential and contaminant metals suggested detoxifying mechanisms mediated by essential metals. The contribution of metal residues in blood coming from deposition in eggs was minimal compared with residues coming from posthatch exposure. Exposure to particulate volatile Pb in the form of dust from fly ash emitted to the air by the SWI is suggested to be the main route of uptake via inhalation, while both dietary and respiratory routes may contribute to Cd uptake. The increasing human population living close to the SWI may be increasingly at risk from exposure to air-borne contaminants depending on the emission standards from the SWI.

Air Pollutants↗

PubMedDate not supplied

Prevention of perinatal morbidity by tight metabolic control in gestational diabetes mellitus.

In a prospective controlled trial, we studied the effect of tight metabolic control on the outcomes of 102 gestational diabetes mellitus (GDM) pregnancies compared with outcomes of 102 matched nondiabetic control pregnancies. Women with GDM were treated to achieve and maintain a blood glucose concentration of less than 130 mg/dl at 1 h after breakfast. Treatment consisted of a diet low in oligosaccharides and fat and, if necessary, once daily insulin. By the end of gestation, 88 of the 102 women with GDM received insulin at a mean dose of 18 U/day. Duration of insulin therapy ranged from 3 to 32 wk with a median of 11 wk. Perinatal outcome of GDM pregnancies under this management equaled that of control pregnancies. The full spectrum of excess morbidity from GDM was prevented, and normal distribution of birth weight and normal rates of macrosomia, dystrophy, hypoglycemia, hypocalcemia, hyperbilirubinemia, fetal acidosis, and low Apgar scores were achieved. No mortality was observed. In addition to the two main study groups, we also studied a third group of 24 women with GDM whose treatment lasted less than or equal to 5 wk due to late diagnosis. This suboptimally treated group demonstrated a significant (P less than .05) increase of macrosomia and umbilical artery acidosis compared with the well-treated GDM group. The study reported herein demonstrates that excess mortality and morbidity typically observed in GDM can be prevented by early institution of tight metabolic control, which required insulin in 86% of our patients.

Birth Weight↗

PubMed1978

Estimation of the critical bandwidth from loudness summation data.

An automatic method for critical band estimation from loudness summation data is presented. A mathematical model, based on a power function, is fitted to the data and the critical bandwidth is defined at the intersection of the asymptotes. The model is designed for clinical use, involving the treatment of the data from single test persons; it represents an operational solution to a difficult task. The model is able to describe data from normals and patients with a sensorineural hearing loss. Variability of the critical band estimates, intrasubject as well as intersubject, is larger than for visually obtained estimates. However, visual estimation is difficult, subjective, and probably heavily biased. The model produces estimates which in logarithmic form have a Normal distribution at medium loudness level, while visual estimation gives rise to irregular distributions at all levels. A normal range for model estimates from sets of data obtained at medium loudness level is defined by mean and standard deviation.

Auditory Perception↗

PubMed1975

[Comparison of the parts in relation to some problems of the statistical processing and planning of cytological experiments].

A possibility is studied of using phi-transformation for comparison of portions in homogenous totalities with intra-group variability. The phi value distribution is approximated satisfactorily by normal distribution, beginning from a certain amount of observation (n) depending on P, P being a portion of cells (individuals) with the character under study. On this basis, a method of statistical treatment and experiment planning is proposed.

Cytogenetics↗

PubMed1990

[Comparison of observed and expected person-years: a simulated approach].

In Epidemiology, no simple test is available for comparing an observed number of exposed person-years with an expected number. The number of person-years is a sum of lengths of stays which is not normally distributed under the null hypothesis. A method is proposed and an example is given. The objective was to study in the French territory of New-Caledonia the relationship between past places of living and occurrence of respiratory cancers. The total observed number of person-years in a zone, among cases, was compared to an expected distribution, based on censuses and controlling for two confounding factors, period of stay and ethnic group. Different methods are compared: a test based on a simulated distribution, and parametric approaches with normality assumption. If the number of cases is small, the simulation test seems to be the best approach.

Analysis of Variance↗

PubMed1989

[Diagnostic specific values of disability duration--a contribution to the epidemiologic analysis of empirical morbidity figures].

In view of the great importance of the disablement period for the sickness figure, a method for interpreting empirical distributions of disablement periods is presented which yields practical information for optimizing diagnosis-specific disablement case periods. By approximating the disablement period distribution via a log-normal distribution, the location parameters mode, median and other quantiles can uniquely determined. The cumulatively determined frequencies of the disablement days with reference to chosen location parameters illustrate the possibilities of maintaining the capacity to work and the necessity of intensifying the medical care if diagnosisuntypical disablement periods are exceeded. To establish these requires further research of concrete long-dated disablement cases.

Absenteeism↗

PubMed1988

[Distributions, mean values and correlations of various coronary risk factors in a population of Veneto].

During the National Research Council (CNR) program called Atherosclerosis-Risk Factors 2 (ATS-RF2) a random sample of 1903 subjects (50.1% male) aged 20-59 years was examined in the general population of Mirano-Venice. Mean values of serum total cholesterol and triglycerides, body mass index, as well as systolic and diastolic blood pressure were assessed. On the whole these turned out to be higher in men and increased with age. The continuously distributed variables showed an approximately normal distribution and a close correlation. Comparing our results with those obtained by other Italian units co-operating in the same CNR program, different levels of serum total cholesterol and systolic blood pressure were observed. The overall risk factor pattern in northern Italian regions is closer to that reported in the literature for central European countries than to that of southern Italian regions. These findings might explain why mortality due to ischaemic heart disease is higher in northern Italy and becomes progressively smaller in central and southern Italy.

Adult↗

PubMed1979

Technetium colloid bone marrow imaging in Fanconi's anemia.

Four patients with Fanconi's anemia were evaluated with 99mTc-sulfur colloid bone marrow scans. The scans revealed similar paradoxical and irregular tracer distribution in all four patients. Normal to increased activity was demonstrated in the proximal metaphyses of the humeri with varying degrees of increased activity in more primitive marrow sites in the distal diaphyses of the humeri and tibia, the distal metaphyses of the humeri and femora, and the proximal metaphyses of the ulnae, radii, and tibia. Skip areas of normal distribution were seen in the proximal diaphyses of the humeri and femora. Although the scan reflects only the reticuloendothelial portion of bone marrow, it may be of some value in the differential diagnosis of pancytopenia.

Abnormalities, Multiple↗

PubMed1993

A statistic study of atmospheric pollen in Japan.

By using a volumetric method, the authors made an investigation on airborne pollen grains in connection with the incidence of pollinosis since 1969, in Toho University, Funabashi, Chiba, Japan. The airborne pollen grains in each sample were counted under the microscope to identify the pollen types, and the pollen grains were classified into seven types according to the classification of pollen grains in Japan reported by Ikuse. In this report, the accumulated number of each species was analyzed statistically by circular plot, semi-logarithmic plot and test of skewness (g1) and kurtosis (g2) of frequency distribution by G. W. Snedecor. From the investigation in the years of 1969, 1970, 1990, 1991, the most frequent airborne pollen grains belonged to the 1-aperturate 3C(ab) type pollen in 1969 and 1970, and to the 1-aperturate 3B type pollen in 1990 and 1991, reflecting the change of environment during twenty years. By the g1 and g2 statistics for almost all species, the mode of distribution curve was significantly smaller than the mean, indicating that the whole distribution significantly skewed from a normal distribution, and the peak was flat for the herbs, while sharp for the trees.

Air↗

PubMed1987

Altitude and birth weight.

The effect of altitude on birth weight was measured with data in U.S. natality records from 1978 to 1981 after correlation with the mean altitude of the mother's resident county. For comparison of the low birth weight (LBW) rate at different altitudes, certain socioeconomic risk factors known to affect birth weight were controlled by the selection of an idealized subpopulation of singleton births. With 500 m gradations for altitude, a curvilinear dose-response relationship of birth weight reduction with increasing altitude was demonstrated (P less than 0.001). In comparison with neonates born at sea level, neonates born at higher altitudes (greater than 2000 m) had a twofold to threefold increase in LBW rate, mainly related to a higher incidence of intrauterine growth retardation. Comparison of the LBW rate on the basis of small geographic divisions in the mountain states showed a positive correlation between the LBW rate and the high altitude. The birth weight frequency distribution curves of the idealized subpopulation at each altitude approximate normal distributions and parallel one another, indicating that altitude has a general effect on all births. Such nearly normal birth weight distributions allowed the determination of altitude-specific LBW cutoff limits that can be used to detect areas of greater risk for LBW but independent of the altitude effect.

Altitude↗