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PubMed2006

[Spatial heterogeneity of soil moisture in Shapotou sand-fixing artificial vegetation area].

To explore the characteristics of soil moisture heterogeneity in sand-fixing artificial vegetation area is of significance in vegetation recovery and environment control in arid regions. With the methods of traditional statistics and geo-statistics, this paper studied the heterogeneity of soil moisture in the layers from 0 to 200 cm in depth in Shapotou sand-fixing vegetation area. The results showed that the variation of soil moisture in layers of 160 to approximately 180 and 180 to approximately 200 cm was relatively larger, with the variation coefficient being 0.72 and 0.73, respectively, and the next was in top layer (0 to approximately 5 cm ), with a variation coefficient of 0.66. Semi-variance analysis showed that the autocorrelation of soil moisture spatial heterogeneity in total spatial heterogeneity was high, ranging from 87.7% to 99.9%. The scale of spatial heterogeneity in different soil layers was different, with the minimum in 60 to approximately 80 cm layer and the maximum in 20 to approximately 40 cm layer, but no regular changes being observed from surface to deep layers. The colorful contour maps of Kriging interpolation indicated that the variation of soil moisture was larger in 0 to approximately 140 cm layer than in 140 to approximately 200 cm layer. The correlation between semi-variance and distance in four directions of 0 degrees, 45 degrees ,90 degrees and 135 degrees was weak, suggesting that the variation of soil moisture was independent, random, and homogeneous.

Conservation of Natural Resources↗
PubMed2006

[Responses of Artemisia ordosica population to soil moisture spatial heterogeneity on semi-fixed dune of Mu Us sandy land].

Spatial heterogeneity affects the functions and processes of ecosystems. By the methods of statistics and geostatistics, this paper approached the relationships between the spatial heterogeneities of Artemisia ordosica and soil moisture on the semi-fixed dune of Mu Us sandy land. The results showed that on plot-scale (80 m x 80 m), the spatial heterogeneity of A. ordosica biomass and density was dependant on that of soil moisture, and in particular, there existed a significant positive correlation between the biomass and the moisture, indicating that on semi-fixed dune, soil moisture played a decisive role in the spatial heterogeneity of plant population. Due to the redistribution of precipitation on sand dune, the outcomes of the interactions between the spatial heterogeneities of soil moisture and A. ordosica population were assumed as patchness of terrain --> patchness of soil moisture distribution --> patchness of A. ordosica population distribution --> patchness of A. ordosica biomass and density.

Artemisia↗
PubMed1991

Various facets of the intercellular heterogeneity in thyroid primary culture.

The mechanisms that generate the intercellular heterogeneity of functional and proliferation responses in a tissue are generally unknown. In thyroid gland, this heterogeneity is peculiarly marked and it was suggested that it could result from the coexistence of (epi)genetically different subpopulations of thyrocytes. As summarized in this short review, qualitative or quantitative intercellular heterogeneities have been found at each levels of our "in situ" investigations of morphological, differentiation and proliferative responses of unselected dog thyrocytes in primary culture. These different heterogeneities are unrelated at the individual cell level, which does not indicate the coexistence in thyroid of cell subpopulations stably expressing special properties. Nevertheless, using a double labeling methodology that allows to trace the proliferative behavior of some cells, we show how cell division may stably affect further proliferation responses and how a local synchrony of the dividing cells can result in a stable heterogeneity with a regional, patchy pattern, which resembles the one characterizing multinodular goiter.

Animals↗
PubMed1991

Heterogeneity of microvascular flow in rat skeletal muscle is reduced by contraction and by hemodilution.

The objective was to test the hypothesis that heterogeneity of microvascular perfusion in a mammalian muscle will decrease with increased flow. We used the extensor digitorum longus muscle in rats to quantify, via intravital video microscopy, (1) the spatial distribution of red cell velocity, VRBC, and (2) density of capillaries with moving and stationary red cells (CDPER, CDSTAT) within a large capillary bed (1.05 x 0.78 mm) at the muscle surface. From the VRBC distribution, the coefficient of variation (CV = SD/mean) was used as an index of VRBC heterogeneity. The flow was increased by two procedures: (1) 1 min supramaximal muscle contraction, and (2) hematocrit reduction from 49 to 21% by isovolemic hemodilution with a 6% PVP-40 (polyvinylpyrrolidone) solution. Among 5 rats studied, the post-contraction and post-hemodilution mean VRBC's were significantly larger than the resting VRBC (1.08 and 0.17 vs. 0.11 mm/s). The corresponding CV's were significantly lower (33 and 49 vs. 60%). The percentages of capillaries with low velocity (0-0.1 mm/s) were also significantly lower (0 and 27 vs. 52%). CDPER values did not differ from the resting level (30.8 cap/mm of test line) but CDSTAT was significantly smaller after contraction (0.8 vs. 4.9 cap/mm). The present data demonstrate that heterogeneity of VRBC in rat skeletal muscle decreases after contraction and after hemodilution. The study shows that hemodilution has a major effect on improving flow in a population of poorly perfused capillaries. Since heterogeneity also decreased after contraction in an amphibian muscle (Tyml, Microvasc. Res. 32: 84-98, 1986), the study supports the view that heterogeneity, in general, is a microcirculatory parameter that reflects the vascular network response to a given tissue stimulus.

Animals↗
PubMed1991

In vivo antitumor activity of a monoclonal antibody-Vinca alkaloid immunoconjugate directed against a solid tumor membrane antigen characterized by heterogeneous expression and noninternalization of antibody-antigen complexes.

It is widely believed that antigen heterogeneity and noninternalization of antigen-antibody complexes will severely limit the antitumor activity of monoclonal antibody-drug conjugates. The B72.3 monoclonal antibody binds to a tumor-associated antigen which is heterogeneously expressed in human carcinomas (J. Schlom, Cancer Res., 46: 3225-3238, 1986). We therefore performed studies to assess the degree of internalization of B72.3 antibody-antigen complexes and the level of in vivo antitumor activity that could be achieved with B72.3 conjugated to 4-desacetyl vinblastine-3-carboxhydrazide. Internalization studies were performed on LS174T colorectal carcinoma and OVCAR-3 ovarian carcinoma cells using iodinated B72.3 as well as an iodinated antibody that binds to the human transferrin receptor, IIB21. These data indicated that, in contrast to HB-21, the B72.3 antigen-antibody complex was not internalized. The B72.3-Vinca alkaloid immunoconjugate demonstrated significant antitumor activity against LS174T xenografts, although complete regressions of established tumors were not achieved. Immunohistochemical analyses indicated that the B72.3 antigen was heterogeneously expressed in the LS174T xenografts and that tumor cells which were not killed by high doses of B72.3-Vinca also expressed the B72.3 antigen. These studies indicated that significant antitumor activity may be achieved by monoclonal antibody-drug conjugates even when antigen heterogeneity and noninternalization of antigen-antibody complexes are encountered. The data also suggested that the formulation of antibody-drug conjugate cocktails to counteract antigen heterogeneity may not be sufficient to eradicate all malignant cells within a solid tumor mass.

Animals↗
PubMed1991

Single-spin density-gradient ultracentrifugation vs gradient gel electrophoresis: two methods for detecting low-density-lipoprotein heterogeneity compared.

Single-spin density-gradient ultracentrifugation (DUC) has proven to be a reproducible method for detection of low-density-lipoprotein (LDL) heterogeneity. Recently another method has been described for this: gradient gel electrophoresis (GGE) of serum, a method that might be more suitable for screening. To gain insight into the relationship of GGE to DUC and into their reproducibility, we determined LDL heterogeneity by DUC and GGE in 41 healthy individuals. In 90.2% (n = 37) of the subjects, the number of LDL subfractions found by both methods agreed. In addition, the density and the relative migration distance of the predominant LDL subfraction observed with the respective methods showed a strong correlation (Pearson correlation, r = 0.85, P less than 0.0001). Although it was not possible to compare for all aspects of LDL heterogeneity, these data suggest that GGE is a valid method of analysis for LDL heterogeneity. In screening programs, it may be necessary to store samples. Therefore, we studied in 24 sera the influence of storage at -80 degrees C for one, four, and 12 weeks on the LDL subfraction distribution detected by each method. LDL heterogeneity was maintained during storage under these conditions.

Adult↗
PubMed1990

A new, highly selective CCK-B receptor radioligand ([3H][N-methyl-Nle28,31]CCK26-33): evidence for CCK-B receptor heterogeneity.

[N-methyl-Nle28,31]CCK26-33 (SNF 8702) is a nonsulfated cholecystokinin octapeptide analog that is highly selective for cholecystokinin-B (CCK-B) receptors. Inhibition studies using [125I] Bolton-Hunter-labeled CCK-8 show that SNF 8702 has over 4,000-fold greater affinity for CCK receptors in guinea pig cortex relative to those in guinea pig pancreas. SNF 8702 was tritium-labeled to a specific activity of 23.7 Ci/mmol and its binding properties characterized for guinea pig brain membrane preparations. [3H]SNF 8702 binds to a single site with high affinity (Kd = 0.69-0.90 nM) in guinea pig cortex, cerebellum, hippocampus and pons-medulla. Of these four tissues, the highest receptor density was measured in the cortex (86 fmol/mg of protein) and the lowest in the pons-medulla (22 fmol/mg of protein). In contrast to findings of single-site binding in some brain regions, evidence for CCK-B receptor heterogeneity is observed under other conditions. [3H]SNF 8702 binding to membranes prepared from whole guinea pig brain shows biphasic association kinetics at a concentration of 2.0 nM consistent with the presence of binding site heterogeneity. Binding site heterogeneity is consistently observed for [3H]SNF 8702 binding to guinea pig whole brain membranes in saturation studies where a high-affinity site (Kd = 0.31 nM) is distinguished from a low-affinity site (Kd = 3.3 nM). Binding site heterogeneity is also observed for the midbrain-thalamic region. CCK-B receptor heterogeneity is suggested by the effect of the guanyl nucleotide analogue, guanylyl-imidodiphosphate (Gpp(NH)p), on [3H]SNF 8702 binding to CCK-B receptors in the cerebellum.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1988

Mechanisms of heterogeneous distribution of monoclonal antibodies and other macromolecules in tumors: significance of elevated interstitial pressure.

The therapeutic efficacy of monoclonal antibodies (MAbs), bound to radionuclides, chemotherapeutic agents, toxins, growth factors, or effector antibodies, depends upon their ability to reach their target in vivo in adequate quantities. Despite the high vascular permeability and interstitial transport coefficients in tumor tissue compared to several normal tissues, MAbs and their fragments do not distribute homogeneously in a tumor. Heterogeneity of tumor-associated antigen expression alone cannot explain this maldistribution of MAbs in tumors. We propose that in addition to the heterogeneous blood perfusion, hindered diffusion in the interstitium, and extravascular binding of MAbs, elevated interstitial pressure is responsible for the poor penetration of MAbs into tumors. Elevated interstitial pressure principally reduces the driving force for extravasation of fluid and macromolecules in tumors, and also leads to an experimentally verifiable, radially outward convection which opposes the inward diffusion. We present here mathematical models for transport of fluid and macromolecules in a tumor. To illustrate the significance of elevated interstitial pressure, these models are used to describe the interstitial pressure, interstitial fluid velocity, and concentration of nonbinding macromolecules as a function of radial position in a uniformly perfused tumor. The key result of these models is that the filtration of fluid from blood vessels in a uniformly perfused tumor is (a) spatially heterogeneous, (b) a result of elevated interstitial pressure, and (c) sufficient to explain the heterogeneous distribution of macromolecules in tumors. Nonuniform blood flow, and extravascular binding would enhance this heterogeneity in the solute distribution considerably. The results of the models also agree with the following experimental data: (a) tumor interstitial pressure is low in the periphery and it increases toward the center of the tumor; (b) the radially outward fluid velocity at the tumor periphery predicted by the model is of the same order of magnitude as measured in tissue-isolated tumors; and (c) immediately after bolus injection, the concentration of macromolecules is higher in the periphery than in the center; however, at later time periods the peripheral concentration is lower than in the center. These results have significant implications not only for MAbs and their fragments, but for other biologically useful macromolecules (e.g., cytokines) produced by genetic engineering for cancer diagnosis and treatment.

Antibodies, Monoclonal↗
PubMed1979

[Importance of the sialic acid moiety for the heterogeneity in human fibrinogen].

To determine whether the observed heterogeneity of gamma- and B beta-polypeptide chains of human fibrinogen (2 and 1 sialic acid residue per chain) is due to differences in sialic acid content, fibrinogen was desialatgen was compared with normal fibrinogen. The gamma-chain heterogeneity observed in normal fibrinogen was absent in asialofibrinogen, whereas the B beta-chain heterogeneity appeared to be unaffected. Although the variants were indistinguishable on SDS-PAGE, isoelectric focusing in the presence of urea demonstrated heterogeneities of both gamma- and B beta-cahins even in asialofibrinogen. However, fewer bands were recognized in asialofibrinogen. The difference in sialic acid content of the gamma- and B beta-chain variants of human fibrinogen therefore explains on part of the polypeptide chain heterogeneity.

Chromatography, Ion Exchange↗
PubMed1982

Mouse mononuclear phagocyte antigenic heterogeneity detected by monoclonal antibodies.

Identification and characterization of the many cellular and subcellular changes that underlie various macrophage functions have been hampered by the problem of population heterogeneity. The problem has remained because, in the case of most functions, we have not had the means to examine cells at a level below that of whole populations. We report here the potential means to do so. Rat anti-mouse mononuclear phagocyte monoclonal antibodies were raised against adherent cells cultured from bone marrow. These antibodies were used to delineate and, in the presence of complement, eliminate subpopulations of macrophages. The extent to which antigenic heterogeneity occurs was shown in several mononuclear phagocyte populations that are commonly employed experimentally. Some antibodies reacted with most mononuclear phagocytes tested, whereas others showed marked selectivity of binding. As expected, resident populations were less heterogeneous antigenically than inflammatory populations were. The data both extend what is known about mononuclear phagocyte population heterogeneity and suggest means by way of which this heterogeneity can be overcome.

Animals↗
PubMed1982

Covariance analyses with heterogeneity of slopes in fixed models.

Techniques that describe the use of covariance when heterogeneity of slopes exists are severely limited. Although a few procedures for model selection have been recommended, none, except the hierarchical approach, is straightforward and usable with present computer programs. The hierarchical subset selection procedure presented in this paper is based on the proposition that heterogeneity may be present only for certain terms in the model. After hierarchical selection, those terms which do not involve heterogeneity are interpreted as in the usual analysis for covariance. The interpretations of those terms which do involve heterogeneity are modified with respect to significance tests performed at various values of the covariate. The hierarchical subset selection method allows one to investigate heterogeneity of slopes in covariance models as functions of the classification variables present in the design.

Analysis of Variance↗
PubMed1982

Clonotypes of anti-phosphocholine antibodies induced with Proteus morganii (Potter). II. Heterogeneity, class, and idiotypic analyses of the repertoires in BALB/c and A/HeJ mice.

The heterogeneity of the PC-specific IgG response of Proteus morganii (Potter) was systematically analyzed. Serum samples from individual mice were focused in paired adjacent tracks, PC-specific antibodies were detected with 125I-PC-RNase, and the resulting autoradiographs were examined for co-focusing bands. Both the number of different antibody band groups and their frequency of expression were determined. Varying qualitatively from simple to complex, the spectrotypes of 38 BALB/c and 19 A/HeJ each appeared unique. However, after thorough analysis for co-focusing bands. It was evident that each spectrotype reflected a unique combination of shared band groups rather than numerous uniquely focusing band groups. The responses of A/HeJ and BALB/c showed striking similarities qualitatively in the appearance of individual spectrotypes. The heterogeneity of the two strains was also similar quantitatively. The basis for this finite though complex heterogeneity was examined by in situ subclass analysis after IEF and idiotype analysis of IEF bands by using antibodies purified from individual BALB/c and A/HeJ. Each mouse primarily expressed IgG3, and antibody bands of this subclass ranged from pI of 6.75 to 8.2. IgG1-positive bands ranged from pI of 6 to 7. Minimal amounts of IgG2 and IgM were detected. In comparisons of individual mice, there was more heterogeneity apparent in the IgG3 subclass than in the IgG1. The idiotype, IdX-M603, was found in both subclasses and also in multiple band groups focusing at different positions within each subgroup. Possible explanations for this heterogeneity among these idiotypically related antibodies are discussed.

Animals↗
PubMed1982

Heterogeneity of red cells in the sickler: a characteristic with practical clinical and pathophysiological implications.

The role of heterogeneity of red cells and its relation to the severity of sickle cell anemia has been examined by the use of spontaneously formed continuous density gradients. We have found that sicklers have a more heterogeneous distribution of cell densities than normals; that this heterogeneity varies greatly from patient to patient; and that this heterogeneity is functionally significant because it involves changes in MCHC and O2 affinity. Extrapolation of HbS solution data to clinical situations will have to account for heterogeneity, and previous efforts to correlate ISC's with severity might have ignored the role of cells with high density but without the classical morphological features associated with these types of cells.

Anemia, Sickle Cell↗
PubMed1982

Modelling the evolution of heterogeneity in residential mobility.

Migration probabilities are known to vary over the population (heterogeneity) and over time (nonstationarity). It is shown that if the heterogeneity is represented by an SB mixing distribution and the nonstationarity by a set of arbitrary logistic scaling functions, then not only may all sources of heterogeneity, including tastes, be modelled, but heterogeneity at different points in time may be readily compared. The model is calibrated using data previously published by Clark et al. (1977, 1979) for a sample of 1,176 older renters and is found to fit well. The changing heterogeneity over the ten-year period of observation is represented graphically.

Demography↗
PubMed1981

Methods for comparing the mortality experience of heterogeneous populations.

Methods are presented which produce Maximum Likelihood Estimates (MLE) of the degree of heterogeneity in individual mortality risks under a variety of assumptions about the age trajectory of those mortality risks. With these estimates of the degree of population heterogeneity it is possible to adjust comparisons of mortality risks across populations for the effects of population heterogeneity, differential mortality selection, and different age trajectories of the force of mortality. These methods are demonstrated by applying a variety of standard assumptions about the age trajectory of the force of mortality to the analysis of a broad range of cohort mortality data for the U.S. and Swedish populations. The estimates of the degree of heterogeneity, produced under all of the selected force of mortality models, consistently indicated a considerable degree of heterogeneity in mortality risks.

Adult↗
PubMedDate not supplied

Magnetic heterogeneity of biological systems.

In biological systems nonuniformity of magnetic susceptibility, magnetic heterogeneity, is a reflection of their physical-chemical and morphological heterogeneity, A characteristic value of heterogeneity is delta K approximately 10(-6)-10(-7) CGS units, a quantitative measurement of susceptibility of cells and other small objects, may give qualitatively new information about their life processes. Patterns and features of movement of small biological objects and liquids affected by magnetic forces were studied. A method was developed for measuring magnetic susceptibility of single microobjects based on observation of movement of the objects in a strong heterogeneous field with parameters (formula: see text) grad H2/2 approximately 10(9)-10(10) Oe2/cm. This method does not require knowing the distribution of the field along the path of movement of the particles, and does not require preliminary calibration. Movement of human erythrocytes, rat hepatocytes, and starch granules in liquids at a point of entry into a gap with the field was observed experimentally. With sufficiently large fields Ho approximately (1-2) x 10(4) Oe, the value of the magnetic force was enough to change the rate of sedimentation movement of the objects appreciably (up to stopping it). This made it possible to compute the value delta K for cells approximately 10(-7)-10(-8) CGS units and to obtain the value of K for starch granules (-0.80 x 10(-6) cGS units). In connection with the fact that sensitivity to gravity in plants is coupled with a disturbance of the intracellular starch granules under the influence of gravity, certain problems of stimulating the effect of gravity on plants by magnetic forces were studied. Noncontact force effect on magnetically heterogeneous biological objects is a promising instrument for biophysical studies.

Animals↗
PubMed1994

[DNA stemline heterogeneity as preoperative prognostic factor in esophageal cancer].

Flow cytometric nuclear DNA analysis was performed on 36 preoperative endoscopic biopsy specimens and 89 surgically resected specimens of esophageal carcinomas without preoperative radiotherapy. Carcinomas with aneuploid or DNA stem-line heterogeneity had a higher frequency of lymph node metastasis (p < 0.01). The correspondence rate of nuclear DNA ploidy patterns was 97% between biopsy and resected specimens, and that of heterogeneity was 72%. Though only six cases showed heterogeneity in biopsy specimens out of 12 cases which showed heterogeneity in resected specimens, preoperative detection of heterogeneity was supposed to be more accurate by an increase of biopsy specimens. DNA analysis of biopsy specimens may be a possible indicator of the malignant potential of esophageal carcinoma.

Biopsy↗
PubMed1994

[Study on relationship between intratumoral DNA heterogeneity and clinicopathological findings in colorectal cancer].

We studied the relationship between intratumoral DNA heterogeneity and clinicopathological findings in 85 colorectal cancers. DNA ploidy was analyzed in 5 specimens from different sites of each tumor. When the difference in the DNA index (D.I) between several peaks in the same tumor was more than 0.1, the tumor was considered to consist of heterogeneous subpopulations with different DNA clones. DNA heterogeneity was found in 34 cases (40.0%). There was no relationship between DNA heterogeneity and depth of tumor invasion, lymph node metastasis or stage. The incidence of heterogeneity was significantly higher in the tumor with lower differentiation, liver metastasis or vessel invasion.

Colorectal Neoplasms↗