Characterization Of Subpopulations Research Articles

Urbanization, mental health, and social deviancy. A review of issues and research.

This article reviews the international research literature on the relationship of urbanization, mental health, and social deviancy. Attention is called to the multidisciplinary and multisectoral nature of the topic, and to its associated definitional, conceptual, and methodological issues and challenges. Selected research literature on rural-urban differences in mental health and social deviancy is reviewed. There is little consensus on the causal relationship between urbanization, mental health, and social deviancy, although numerous environmental and social pathogenic processes have been posited and investigated. Data indicate rural and urban milieus can have both pernicious and salutary consequences and that more research is needed to specify critical etiological factors and their relationship to subpopulation characteristics. Suggestions for improving future research efforts are offered, including the use of more complex theoretical models, measurement indices, and data analysis procedures.

Flow cytometric analysis of platelet activation and fibrinogen binding

Human blood platelets can be activated by a variety of physiological activators such as adenosine diphosphate (ADP), thrombin or collagen, leading to activation of GPIIb-IIIa into a high-affinity receptor for Fg (FgR), binding of fibrinogen (Fg), and subsequent platelet aggregation required for normal hemostasis. Although enormous progress has been made in the biochemistry of platelet activation, of the platelet membrane GPIIb-IIIa, and of solution Fg, much less is known of the dynamics of expression of FgR, of its occupancy by Fg, and of their relation to the dynamics of platelet aggregation. Since platelet activation and aggregation occur within ∼1 s of stirring with activators such as ADP, a methodology was required for determining the rapid dynamics of expression of FgR and binding of Fg, and their correlation with platelet aggregation kinetics. We therefore developed the theoretical and experimental base for determining these dynamic changes under non-equilibrium conditions, using fluorescently-labelled probes and flow cytometry. This approach has yielded a novel general technique for assessing the rapid dynamics of any cell surface molecule, as well as unexpected new insights into the kinetic expression and nature of FgR formed on platelet surfaces activated with ADP and PMA. The same approach has been extended to an analysis of the size-dependent (subpopulation) behaviour of platelets in expressing FgR, obtainable by analytically selecting platelets of different size from forward scatter profiles obtained in studies of the whole population. Parallel measurements of kinetics of platelet recruitment into microaggregates and expression and Fg occupancy of FgR as a function of ADP concentration, led to an unexpected new model for platelet activation and recruitment based once again on the selective recruitment of platelet subpopulation and an 'all or none, quantal' response of any single platelet in expressing all of its FgR and becoming recruitable for aggregation, but at a critical ADP concentration dependent on its own subpopulation characteristics. This approach has also led to novel insights into problems associated with platelet 'activation' arising with different isolation procedures. Dynamic binding studies of Fg to FgR on activated platelets has become possible using appropriately FITC-labelled Fg and flow cytometry. This has also led to studies of the relation between shear-dependent capture efficiency of platelets into doublet formation and the fraction of Fg-occupied receptors. In addition, we have successfully used FITC-labelled human and bovine Fg to demonstrate a delayed expression of FgR and Fg binding to ADP-activated platelets from bleeding Simmental cattle, although the final expression of numbers and accessibility of FgR, measured at equilibrium, were normal. Some future directions for dynamic flow cytometric studies of platelet activation and function are discussed.

Flow cytometric analysis of apoptosis and BCL‐2 in human solid neoplasms

Apoptosis (programmed cell death) and the genes regulating this process (e.g., bcl-2), have recently become a focus of interest in the study of cancer development and progression. We adapted flow cytometric techniques for measuring apoptosis and bcl-2 protein in solid tissues and concomitantly determined both parameters in 65 malignant solid neoplasms. Four different fixation methods were evaluated for bcl-2 analysis using a lymphoma cell line possessing a t(14;18), and the Daudi cell line as positive and negative controls, respectively; optimal fixation was achieved using 70% ethanol. Apoptosis was determined using the terminal deoxynucleotidyl transferase (TdT) end-labeling method of (Gorczyca et al.: Cancer Res 53:1945-1951, 1993). Treated (5Gy radiation, 4 h) and untreated portions of a murine cell line were used as positive and negative controls for apoptosis induction. For tumor specimens, bcl-2 positivity ranged from 0 to 89.5% (15.8 +/- 22.9), and apoptosis (TdT end-labeling) ranged from 0.4 to 84.3% (15.9 +/- 17.0). Generally, tumors with high bcl-2 expression (> or = 20.0%) showed significantly lower numbers of apoptotic cells than those with low (< 20.0%) bcl-2 (P = 0.05). A subset of tumors, however, exhibited low values for both parameters. We also observed that the proliferative fractions of tumors with high apoptosis (> or = 15.0%) were significantly different from those with low (< 15.0%) apoptosis (P = 0.005); higher proliferative rates were associated with high apoptosis. We conclude that optimal bcl-2 analysis is achieved using ethanol fixation and that flow cytometry provides a rapid and reliable technique for the measurement of these parameters. Concurrent analysis of these markers provides detailed information on the biological characteristics of tumor subpopulations and may assist in categorizing tumors for different management strategies.

Selective Versus Nonselective Losses in Glaucoma

This article reviews the histopathologic and psychophysical evidence for selective losses to specific subpopulations of optic nerve fibers in glaucoma. Based on this evaluation, the degree to which these losses are selective is drawn into question, and a distinction is drawn between selective tests and selective losses. An alternative hypothesis for early detection of functional losses in glaucoma, the reduced redundancy hypothesis, is presented. This concept takes into account the redundancy or sampling characteristics of specific subpopulations of optic nerve fibers, as well as the relative amount of glaucomatous loss incurred by each optic nerve fiber subpopulation. An example is presented in which an undersampled subpopulation of optic nerve fibers with minimal redundancy is better able to reveal early losses, even though there are greater amounts of relative loss for other optic nerve fiber subpopulations. The design of psychophysical tests for early detection of functional losses in glaucoma should take into account both the relative amounts of loss for various subpopulations of optic nerve fibers and their inherent redundancy or sampling properties.

Morphofunctional Aspects of Melanotrope Cell Heterogeneity

New data show that differential responses to physiological stimuli by cells of one endocrine cell type depend on differential morphological and physiological characteristics of subpopulations of cells. In this work, we present evidence for the existence of cell heterogeneity in the frog intermediate pituitary lobe, in both morphological and physiological aspects.

Morphologic and functional characteristics of subpopulations of murine lung fibroblasts grown in vitro.

Fibrotic development is a common response of the lung to toxic or deleterious insult. For example, the lung is the dose-limiting organ for irradiation of the thorax for primary or metastatic lesions, due in large part to latent fibrosis. The development of the fibrotic response reflects a cascade of cell-cell and cell-extracellular matrix interactions, the ultimate target of which is the fibroblast. There is increasing evidence of subpopulations of pulmonary fibroblasts, which may have differing roles in either the initiation or progression of fibrosis. Recently we described two fibroblast subpopulations from the murine lung, which differ in the presence or absence of the membrane antigen Thy-1 (Phipps et al., 1989). These Thy-1+ and Thy-1- subpopulations are stable and differ in certain functions, such as the production of cytokines and the display of Class II MHC antigens. To determine the morphologic development of the two subpopulations and their growth characteristics in vitro, cultures of the two cell subtypes were prepared for transmission and scanning electron microscopy at varying stages of growth. Thy-1+ fibroblasts are more spindle-shaped, contain intracellular lipid, exhibit abundant cell-cell contacts, and are capable of secreting large amounts of collagen and modest amounts of fibronectin. Thy-1- fibroblasts are more rounded and spread, contain no intracellular lipid droplets, possess more intracellular microfilaments and microtubules, and synthesize less collagen and more fibronectin than do Thy-1+ cells. There are no significant differences between the two subpopulations insofar as growth rates are concerned, but Thy-1+ fibroblasts possess an additional DNA peak during periods of early growth.

Sampling and Weighting in the National Assessment

This chapter describes procedures for obtaining the National Assessment of Educational Progress (NAEP) student samples used in the national and state assessments and for deriving survey weights for use in the analysis of the survey data. Following the description of general procedures, more detailed discussion is included about several issues that relate to the procedures used. In some cases, these involve procedures that NAEP is actively reviewing and investigating, with a view toward implementing improvements in the future. In other cases, the procedures, although well established in NAEP, involve technical aspects with interesting features not fully described in the available technical reports. Probability sampling techniques are used to select the student samples for the national assessment and for the Trial State Assessment program. The sample designs for these two types of samples depend on each other only in the implementation of procedures to minimize the overlap of the samples of participating schools. For both the national assessment and the Trial State Assessment, the goal of the sample design is to obtain samples of students from which estimates of subpopulation characteristics can be obtained with reasonably high precision while satisfying economic and operational constraints. We will describe the procedures used to obtain the student samples used in the national and state assessments and to derive survey weights for use in the analysis of the survey data. Additionally, we will discuss several

Effects of macrophage colony-stimulating factor on reduction of viable bacteria and survival of mice during Listeria monocytogenes infection: characteristics of monocyte subpopulations

Mice could well tolerate infection with a lethal dose of Listeria monocytogenes after intraperitoneal preinjections with 250 micrograms of macrophage colony-stimulating factor (M-CSF) per kg of body weight for 5 days. The characteristic changes in the surface markers (Mac-1, LFA-1, and F4/80) of peripheral monocytes were also investigated in order to analyze the mechanism of protection by M-CSF. This investigation shows the excellent effect of intraperitoneal preinjections of M-CSF on the reduction of viable Listeria organisms and the improvement of survival after an intravenous Listeria infection.

Applications of flow cytometry to artificial insemination: a review

Flow cytometry is a technique in which sub-populations of cells can be analysed and separated according to the staining pattern seen with various fluorescent markers. This review describes some of the ways in which flow cytometry can be applied to the investigation of sperm populations, either as a means of quality control of semen or to examine the characteristics of different sub-populations of sperm within an ejaculate. These methods can replace or augment existing subjective assessments of semen characteristics. Using this technique it is possible to produce aliquots of sexed sperm for insemination or for in vitro fertilisation. An objective assessment can be made of the effects of environmental stress on male physiology by monitoring changes in semen quality.

Lymphocyte subsets in granulomas of human tuberculosis: An in situ immunofluorescence study using monoclonal antibodies

The immunophenotypic characteristics of lymphocyte subpopulations in tissue lesions of human tuberculosis were investigated in 18 cases. Frozen sections of affected cervical lymph nodes were stained with a panel of monoclonal antibodies using avidin-biotin immunofluorescence technique. The mean percentage of cells staining with different antibodies was as follows: CD3 44%; CD4 43%; CD8 36%; HLA-DR 86%; and IgM 29%. The mean CD4/CD8 ratio was 1.3:1. Leu7 and CD1 staining cells were very sparsely distributed in the granulomas. Thus, infection with tuberculosis is associated with a predominantly T cell infiltrate in lesional tissues. The proportion of CD4 positive (helper/inducer) cells at these sites is much lower than that seen (i) in the normal circulation, (ii) in reactive lymph nodes and (iii) at the site of purified protein derivative (PPD) injection in healthy tuberculin-responsive individuals.

Endothelial cell subpopulations in vitro: cell volume, cell cycle, and radiosensitivity.

Vascular endothelial cells (EC) are important clinical targets of radiation and other forms of free radical/oxidant stresses. In this study, we found that the extent of endothelial damage may be determined by the different cytotoxic responses of EC subpopulations. The following characteristics of EC subpopulations were examined: 1) cell volume; 2) cell cycle position; and 3) cytotoxic indexes for both acute cell survival and proliferative capacity after irradiation (137Cs, gamma, 0-10 Gy). EC cultured from bovine aortas were separated by centrifugal elutriation into subpopulations of different cell volumes. Through flow cytometry, we found that cell volume was related to the cell cycle phase distribution. The smallest EC were distributed in G1 phase and the larger cells were distributed in either early S, middle S, or late S + G2M phases. Cell cycle phase at the time of irradiation was not associated with acute cell loss. However, distribution in the cell cycle did relate to cell survival based on proliferative capacity (P less than 0.01). The order of increasing radioresistance was cells in G1 (D0 = 110 cGy), early S (135 cGy), middle S (145 cGy), and late S + G2M phases (180 cGy). These findings 1) suggest an age-related response to radiation in a nonmalignant differentiated cell type and 2) demonstrate EC subpopulations in culture.

Characteristics of lymphocyte subpopulations isolated from persons in normal health and with nonspecific ulcerative colitis

Characteristics of lymphocyte subpopulations isolated from persons in normal health and with nonspecific ulcerative colitis

Quantitation of the immunocytochemical assay for estrogen receptor protein (ER-ICA) in human breast cancer by television imaging.

A Quantimet 720D Image Analysis System has been programmed for light microscopic evaluation of the nuclear estrogen receptor distribution in frozen sections of human breast cancer stained by the peroxidase-antiperoxidase method using monoclonal antibodies to estrogen receptor protein (ER). This method provides precise criteria for distinguishing ER-positive and -negative cells and a sensitive and reproducible means for densitometric quantification of the staining patterns. Although imaging sequence and graphic analysis are automated by computer programs, light pen interaction provides supervision of feature selection. Imaging of the immunocytochemical assay (ER-ICA) in 50 patients revealed marked heterogeneity of nuclear estrogen receptor concentration varying over a nearly 100 fold concentration range. Various ER concentration patterns were evident: (I) distributions with a single peak (CV = 5%) present at various concentration levels; (II) bimodal distributions, revealing co-existent ER-positive and ER-negative subpopulations; (III) multimodal distributions with a number of resolvable concentration peaks; and (IV) highly skewed distributions with or without discernible peaks, frequently extending over the entire concentration range. Statistical methods of de-convolution were applied to determine the frequency and ER concentration characteristics of component subpopulations in the mosaic cases and for resolving the proportion of ER-positive and -negative cells. An approach for evaluating nuclear ER content in conjunction with ER concentration patterns in individual patients revealed whether spread in the ER concentration distribution resulted from differences in nuclear ER content or from variability in nuclear volume distribution.

Morphological and functional characteristics of subpopulations of amoebocytes in the snail Lymnaea Stangalis: Effect of infection with Trichobilharzia ocellata: [formula omitted], [formula omitted], [formula omitted] and [formula omitted]. Lab. Med. Parasitol., Free University, P. O. Box 7161, Amsterdam, The Netherlands

Morphological and functional characteristics of subpopulations of amoebocytes in the snail Lymnaea Stangalis: Effect of infection with Trichobilharzia ocellata: [formula omitted], [formula omitted], [formula omitted] and [formula omitted]. Lab. Med. Parasitol., Free University, P. O. Box 7161, Amsterdam, The Netherlands

Alterations in lymphocyte subpopulations in copper-deficient mice.

Analyses of cell surface determinants of splenocytes from copper-deficient C58 mice indicate alterations in lymphocyte subpopulation characteristics. Both the absolute number and the relative percentage of surface immunoglobulin-bearing (B) cells from copper-deficient mice were significantly greater than those from copper-supplemented controls. The relative percentage of Thy 1.2-positive (T) cells was decreased, and the decrease was most prominent within the Lyt 1-positive (helper) T-cell subset. The functional responsiveness of both B cells and T cells was decreased in copper deficiency.

Characteristics of pathogenic subpopulations of antibodies to DNA.

Characteristics of pathogenic subpopulations of antibodies to DNA.

Do childhood cancers result from prenatal x-rays?

An independent review of the published data from the Oxford Survey of Childhood Malignancies is presented. Publications of the Survey point out that the mothers of the children who died of cancer had a greater incidence of abdominal X-rays during pregnancy than the control group, and they attribute the difference in incidence to a cancer-causing effect of the X-rays exerted on the fetuses. Although this association of prenatal X-rays with cancer decreased for children born after 1957, the residual implied radiation effect is much larger than could be expected from the direct experience at Hiroshima and Nagasaki. The “crude dose-response” curves that have been published are shown to be faulty; they do not substantiate the existence of a casual relationship between prenatal X-rays and childhood cancer. Examination of the method used to calculate “relative risk” from X-rays shows that it requires an assumption that the sub-population of cancer cases has the same probability of being X-rayed as the sub-population of controls. The published data show that this is not the case and that, therefore, there is no basis for estimating any casual relationship. In fact, the sub-population of cancer cases is different from the control population in ways that indicate a greater need for medical care, with its associated X-ray procedures. Thus, the greater frequency of X-raying of the mothers of the children who died of cancer can be accounted for entirely by differences in sub-population characteristics.

Phylogeny of immunocompetent cells: III. Mitogen response characteristics of lymphocyte subpopulations from normal and thymectomized frogs ( Xenopus laevis)

Thymectomy during very early larval life, together with an analysis of in vitro proliferation of adult lymphocytes cultured with selective mitogens, has confirmed the existence of thymus-dependent and -independent populations of frog lymphoid cells. Mitogen reactivities of unfractionated lymphocyte suspensions from the spleen, blood, liver, bone marrow, and thymus revealed additional heterogeneity and organ compartmentalization; density gradient analyses of cells from the same tissues further disclosed that thymus-independent (PPD responsive) cells closely followed the total cell distribution, whereas thymus-dependent (Con A and PHA) responses were consistently a function of low density cells. Data are discussed from a phylogenetic perspective.

Surface characteristics of separated subpopulations of mouse teratocarcinoma cells

Specific subpopulations of 129/J mouse teratocarcinoma cells were separated by velocity sedimentation in shallow density gradients using unit gravity or centrifugal force. The subpopulations were examined with perspective plots generated by a computer program. These plots permitted 360 ° rotation of the horizontal axis making it possible to examine the symmetry of the major cell populations. The teratoma consistently separated into two major populations of cells: ‘large’ cells and ‘small’ cells. Although the small and large cells bound many of the eight lectins tested, only the large cells agglutinated in the presence of low concentrations of lectins. The large cells, therefore, are more malignant-like than the small cells with respect to their agglutinability characteristics. This work demonstrates that a heterogeneous, in vivo teratocarcinoma tumor can be separated into specific cell populations that clearly differ with respect to certain cell surface characteristics.

Field Studies and Model Simulation of the First Square Event in Cotton1

AbstractThe ability of cotton (Gossypium hirsutum L.) production models to accurately predict the first‐square event is essential for estimating square and boll production rates. A first‐square model was formulated which requires three plant character inputs: 1) mainstem node number limits for first‐square positions, 2) characterization of fist‐square distribution between the mainstem node limits, and 3) a measure of the variability of mainstem node generation times and one environmental parameter—mean daily air temperature.Observations were made in field populations of 200 plants grown in rows spaced 101.6 cm at population densities of 98,900 plants/ha. Canparison of model simulations with the field observations in which the cultivars ‘Paymaster 909,’ ‘Paymaster 303,’ and ‘Acala 3080’ were used indicated close agreement between simulated and observed cumulative first‐square curves. The firstsquare characteristics of subpopulations of plants that emerged on the same day (Day 2 or Day 4) were most accurately simulated by beginning the simulation on the day of initial emergence for the total population. This result suggested that germination and development of seedlings that emerged as late as 3 days after the earliest plants probably began simultaneously with the earliest seedlings.Sensitivity analysis was utilized for examination of the relative influence of model parameters on the firstsquare event. Raising the position limits of the first‐square node from the interval 4 and 9 to the interval 6 and 11 increased the length of the first‐squaring period from 22 to 25 days. Changing the distribution of limit squares between the node position limits by doubling the value of the binomial distribution parameter p from 0.3 to 0.6 caused the firstquaring period to increase from 20 to 23 days. Inoreasing the mean variance of mainstem‐node generation time from 0.1 to 0.4 increased the first‐squaring period from 22 to 23 days. Mean daily air temperature had the greatest effect on the first‐squaring period; a decrease in temperature from 27 to 21 C increased the length of the first‐squaring period from 15 to 35 days.