Cell-substrate adhesion and metastatic potential of cultured mesothelioma cells induced by asbestos

Cell-substrate adhesion was quantified for two cultured mesothelioma cell lines (epitheliomatus and sarcomatous) on glass, fibronectin and laminin substrates. Interference reflection microscopy (IRM) was used to image the adhesion patterns of cells and a grey level analysis was employed to quantify adhesion. Sarcomatous cells demonstrated marked adhesion to glass and fibronectin-coated substrates but not to laminin-coated substrate, with the greatest adhesion occurring on the fibronectin-coated surface. This adhesion was accompanied by cytoplasmic spreading. By contrast, epitheliomatous cells showed little tendency to adhere to any of the substrates and only showed significant spreading when in contact with the laminin substrate (P < 0.01). A bioassay was used to determine the metastatic potential of each of the cell lines. Via the intravenous route, the sarcomatous cells killed the host rats in 24.7 ± 1.5 (S.D.) days compared to 27.3 ± 0.9 (S.D.) days for the epitheliomatous cells (P < 0.01). After subcutaneous inoculation of tumour cells, the sarcomatous cells killed the host rats in 54.7 ± 0.7 (S.D.) days compared to 48.5 ± 0.5 (S.D.) days for the epitheliomatous cells (P < 0.01). We conclude that the results of the metastasis bioassays were consistent with the predicted behavior of these cell lines based on their ability to adhere to substrates in the in vitro adhesion assays.     

Cobalt determination in serum and urine by electrothermal atomic absorption spectrometry

Cobalt determinations in biological fluids are of great interest in biological or toxicological research programs. Cobalturia is often chosen as an indicator for a biological monitoring program in occupational exposure to cobalt dusts. The method described here derives from the IUPAC reference method for nickel determination. It enables cobaltemia and cobalturia to be measured in small samples (1 mL). The mean usual values for cobalt in biological fluids are very low (2.7 nmol L⁻¹ for serum and 6.7 nmol L⁻¹ for urine), and therefore, thus require an analytical procedure with preconcentration and extraction. The sample is mineralized by wet acid digestion. After digestion, inorganic cobalt is extracted in form of ammonium pyrrolidine dithiocarbamate complex into isobutyl methyl ketone and measured in the organic layer by electrothermal atomic absorption spectrometry. The analytical parameters are described in detail. The extraction output is about 99%. The detection limits are 1.93 and 1.89 nmol L⁻¹ for serum and urine, respectively. Sensitivity (expressed as the concentration that gives a 0.044 absorbance) is 3.4 nmol L⁻¹ for serum and 3.3 nmol L⁻¹ for urine. Within-run precision ranged between 3.9 and 2.5% (coefficients of variation) for serum and 4.2 and 1.1% for urine, at 87 and 136 nmol L⁻¹ levels, respectively. Between-run precision ranged between 4.3 and 3.3% (coefficients of variation) for serum and 4.2 and 2.3% for urine, at 87 and 136 nmol L⁻¹ levels, respectively. At very low concentration, 5.7 nmol L⁻¹ for serum and 2.5 nmol L⁻¹ for urine, the between-run precision is, respectively, 19.5 and 28%. Linearity is effective between 0 and 272 nmol L⁻¹. Interferences and matrix effects are negligible for urine, serum, or plasma samples without hemoglobin. The method is easily applicable for routine determinations.     

Rapid neurotrophic actions of an ACTH/MSH(4–9) analogue after nigrostriatal 6-OHDA lesioning

ACTH peptide fragments demonstrate potent neurotrophic effects on peripheral nerves in situ, central neurons in culture, and have been implicated to have effects on central neurons in vivo. Neurotoxic lesioning of the nigrostriatal system, which depletes the striatum of dopamine, provides a feasible model of central regeneration in which to test these peptides. Male Sprague-Dawley rats were lesioned unilaterally with 6-hydroxydopamine (8 μg/4 μl), infused into the substantia nigra. They were subsequently treated with 10 μg/kg IP of Org 2766 [ACTH/MSH(4–9) analogue] or saline every 24 h starting immediately after the infusion and were observed for 2 weeks. Rotational behavior data indicate that Org 2766 significantly decreases ipsiversive turning (p < 0.05), induced by amphetamine (2 mg/kg), as well as accelerating the onset of denervation supersensitivity induced by apomorphine (0.05 mg/kg). Evaluation of dopamine immunohistochemistry, using an anti-tyrosine hydroxylase antibody, demonstrates an enhanced intensity of staining in the ORG 2766-treated tissue compared to its saline counterpart. This difference is confirmed and quantified through specific high-affinity dopamine uptake. Dopamine uptake is about 17% higher in the striata of animals treated with Org 2766. Higher dopamine uptake levels in these ACTH-treated animals correlate with greater fiber density in this group. Therefore, it appears that treatment with the ACTH/MSH(4–9) analogue Org 2766 (10 μg/kg/24 h) offers a protective effect from 6-OHDA lesions in the substantia nigra as well as accelerating various compensatory mechanisms involved in functional recovery.     

BRCA1 maps proximal to D17S579 on chromosome 17q21 by genetic analysis

Previous studies have demonstrated linkage between early-onset breast cancer and ovarian cancer and genetic markers on chromosome 17q21. These markers define the location of a gene (BRCA1) which appears to be inherited as an autosomal dominant susceptibility allele. We analyzed five families with multiple affected individuals for evidence of linkage to the BRCA1 region. Two of the five families appear to be linked to BRCA1. One apparently linked family contains critical recombinants, suggesting that the gene is proximal to the marker D17S579 (Mfd188). These findings are consistent with the maximum-likelihood position estimated by the Breast Cancer Linkage Consortium and with recombination events detected in other linked families. Linkage analysis was greatly aided by PCR-based analysis of paraffin-embedded normal breast tissue from deceased family members, demonstrating the feasibility and importance of this approach. One of the two families with evidence of linkage between breast cancer and genetic markers flanking BRCA1 represents the first such family of African-American descent to be reported in detail.     

The decline of tree diversity on newly isolated tropical islands: A test of a null hypothesis and some implications

Summary Six islands, each less than a hectare in area, were isolated in about 1913 from the mainland of central Panamá by the rising waters of Gatun Lake. By 1980, the diversity of trees on all but one of these islands was far lower than on mainland plots of comparable size. A restricted subset of tree species has spread on these islands, notablyProtium panamense, Scheelea zonensis, Oenocarpus panamanus andSwartzia simplex. We constructed a null model to predict how chance would change tree diversity and the similarity of tree species compositions of different islands, assuming that each mature tree has equal chances of dying and/or reproducing, regardless of its species. This model cannot account for the diminished diversity of the changes in vegetation on these islands: some factors must be favoring a particular set of tree species.Two factors, exposure to wind and absence of mammals, seem needed to bring about the vegetation changes observed on these small islands. Their vegetation shows many signs of wind damage and of adaptation to resist wind, reflecting its exposure to dry season winds and storm winds sweeping across the lake from the west. Their most common tree species appear to have spread because mammals rarely visit these small and isolated islands. Seed of these common species are normally much eaten by mammals and do not need burial by mammals to escape insect attack.A thorough grasp of plant—animal interactions is needed to understand the events that have taken place on these islands. Identifying those keystone animals essential for maintaining plant diversity is a necessary element of reserve design and forest management in the tropics.The US government has the right to retain a non-exclusive, royalty-free license in and to any copyright covering this paper.     

Two novel microsatellite markers for prenatal prediction of spinal muscular atrophy (SMA)

Autosomal recessive spinal muscular atrophy (SMA) has been mapped to a 6-cM interval on chromosome 5q12–13.3, flanked proximally by locus D5S6 and distally by locus D5S112. In this study we describe the isolation of two new microsatellite markers (EF1/2a and EF13/14) near locus D5S125, which lies 2 cM distal to D5S6. We show by linkage analysis and the study of the recombinants in 55 SMA pedigrees that the disease lies in the 4-cM interval between EF1/2a and D5S112. Fluorescence in situ analysis of cosmids from D5S6, EF1/2a and D5S112 confirms the genetic order and relative distance of markers. The microsatellites EF1/2a and EF13/14 are the first highly polymorphic PCR based proximal markers in SMA to be described, and will be of value in prental prediction of the disorder.     

Synthesis and evaluation of the antidepressant activity of the enantiomers of bupropion

The synthesis of the enantiomers of bupropion, (rac)-2-tert-butylamino-3′-chloropropiophenone 1 (Wellbutrin®) is described. The enantiomers were compared with the racemate in both the tetrabenazine-induced sedation model and the inhibition of uptake of biogenic amine assay. No significant differences were found in their potencies to reverse tetrabenazine-induced sedation in mice or in their IC₅₀ values as inhibitors of biogenic amine uptake into nerve endings obtained from mouse brain. © 1993 Wiley-Liss, Inc.     

The Mechanochemistry of Muscular Contraction : I. The isometric twitch

The dependence of PC¹ and ATP¹ dephosphorylation on the number of isometric twitches in the iodoacetate-nitrogen-poisoned muscle has been examined. There is no net dephosphorylation of adenosinetriphosphate. PC dephosphorylation varies linearly with the number of twitches and produces equivalent amounts of C¹ and P_1i.¹ Iodoacetate concentrations which block the enzyme, creatine phosphokinase, render the muscle non-contractile. A value of 0.286 µmole/gm. for the amount of PC split per twitch is obtained which gives a value of -9.62 kcal./mole for the "physiological" heat of hydrolysis of PC in agreement with expectations based on thermochemical data. In a single maximal isometric twitch it is estimated that 2 to 3 PC molecules are dephosphorylated per myosin molecule, or 1 per actin molecule. The results support the view that under the conditions of these experiments PC dephosphorylation is the net energy yielding reaction. The in vivo stoichiometry of the mechano-chemistry of contraction revealed by these studies on the one hand, and the known stoichiometry of actin polymerization and its coupling to the creatine phosphokinase system on the other are strikingly similar and strongly suggest that the reversible polymerization of actin is involved in a major way in the contraction-relaxation-recovery cycle of muscle.     

Effect of exercise intensity on the postexercise sweating threshold.

The hypothesis that the magnitude of the postexercise onset threshold for sweating is increased by the intensity of exercise was tested in eight subjects. Esophageal temperature was monitored as an index of core temperature while sweat rate was measured by using a ventilated capsule placed on the upper back. Subjects remained seated resting for 15 min (no exercise) or performed 15 min of treadmill running at either 55, 70, or 85% of peak oxygen consumption (V(o2 peak)) followed by a 20-min seated recovery. Subjects then donned a liquid-conditioned suit used to regulate mean skin temperature. The suit was first perfused with 20 degrees C water to control and stabilize skin and core temperature before whole body heating. Subsequently, the skin was heated ( approximately 4.0 degrees C/h) until sweating occurred. Exercise resulted in an increase in the onset threshold for sweating of 0.11 +/- 0.02, 0.23 +/- 0.01, and 0.33 +/- 0.02 degrees C above that measured for the no-exercise resting values (P < 0.05) for the 55, 70, and 85% of V(o2 peak) exercise conditions, respectively. We did note that there was a greater postexercise hypotension as a function of exercise intensity as measured at the end of the 20-min exercise recovery. Thus it is plausible that the increase in postexercise threshold may be related to postexercise hypotension. It is concluded that the sweating response during upright recovery is significantly modified by exercise intensity and may likely be influenced by the nonthermal baroreceptor reflex adjustments postexercise.