Leukotrienes (LTC4, LTD4) confer glass non-adherence on leukocytes of asthmatic individuals. Dependency on cyclooxygenase products and calcium ion

It has been suggested that cysteinyl-containing leukotrienes (LT) are important mediators in bronchial asthma. Since leukotrienes have been shown to mediate the leukocyte adherence inhibition (LAI) phenomenon observed in cancer-bearing host we have devised a modified LAI assay which determines the acquisition of non-adherence properties of leukocytes following a challenge with pure synthetic LT. Our results demonstrate that peripheral blood leukocytes of asthmatic individuals acquire non-adherence properties when challenged with pure synthetic leukotriene C₄ and D₄, a property not shared by peripheral blood leukocytes of control healthy individuals. Furthermore, we demonstrate that LT activity as manifested by the LAI assay is dependent on cycloxygenase products, since 2×10⁻⁶ M Indomethacin abrogated the LT-induced LAI and is restored by the addition of 2×10⁻⁶ M prostaglandin E₂ which is also synergistic to LT activity. Our results further suggest the possibility that leukotriene activity is dependent on calcium ions since it was negated by known calcium antagonists. It is thus suggested that the LT-induced LAI may serve as a tool for the study of the interrelationship between the metabolic pathways of arachidonic acid and calcium ion homeostasis.     

Intracellular Ca antagonist TMB-8 blocks catecholamine secretion evoked by caffeine and acetylcholine from perfused cat adrenal glands in the absence of extracellular Ca

Unlike acetylcholine, caffeine was much more effective in releasing catecholamine in the absence of extracellular Ca²⁺ than in its presence in perfused cat adrenal glands. The intracellular Ca²⁺ antagonist, TMB-8 (10⁻⁴ M), inhibited reversibly the catecholamine secretion evoked by caffeine (40 mM) and that induced by acetylcholine (10⁻⁴ M) in the presence of hexamethonium (10⁻³ M) during perfusion with Ca²⁺-free Locke solution containing EGTA (10⁻⁵ M). These results support our view that muscarinic receptor activation causes catecholamine secretion by mobilizing Ca²⁺ from an intracellular pool just as caffeine does.     

Dual effect of verapamil on K-evoked release of endogenous dopamine from arcuate nucleus-median eminence complex

The effect of verapamil, a calcium-entrance blocker, on K⁺-evoked release of endogenous dopamine from tuberoinfundibular neurons incubated in vitro was studied. This compound, added to the incubation medium, at the dose of 10⁻⁶ M, significantly reinforced K⁺-induced dopamine release, whereas, at higher doses (10⁻⁵, 5 × 10⁻⁵ and 10⁻⁴ M), it completely prevented the stimulated dopamine release. The results obtained with the higher doses showed the calcium dependence of K⁺-evoked release of endogenous dopamine from central neurons. The opposite effect, seen with the lower dose of verapamil, could be due to different pharmacological properties of the drug.     

Binding specificity of a class II-restricted hepatitis B epitope by DR molecules from responder and nonresponder vaccine recipients

A small but significant proportion of people who receive the hepatitis B vaccine do not produce anti-hepatitis B antibodies, a phenomenon associated with certain human leukocyte antigen (HLA) class II haplotypes. We were interested in determining whether natural allelic differences between two HLA-DR4 molecules associated with responder versus nonresponder subtypes differed with respect to binding of an immunodominant hepatitis B surface antigen (HBsAg) peptide as measured using a resonant mirror biosensor. In contrast to our original hypothesis, we found a ten-fold difference in the affinity in favor of the nonresponder DRB1*0401 allele, with a K_D of 6.89 × 10⁻⁸ M versus a K_D of 6.71 × 10⁻⁷ M for the responder DRB1*0404 allele. Half-times of dissociation were 1.3 min and 7.7 min, respectively, although association rate constants for both HLA class II molecules were similar (approximately 10⁴ M⁻¹s⁻¹). Of particular interest was the observation of different on-rates during the association phase, suggesting that stoichiometry of binding was not 1:1 or that different structural forms of the HLA-peptide complex exist. Our observations indicate that whereas HBsAg peptide binding to HLA class II molecules is influenced by HLA polymorphism, the nonresponse to hepatitis B vaccine associated with this HLA-DR4 subtype is not a result of failure of processed HBsAg to bind HLA class II molecules.     

Trophic action of pharmacological substances with a guanidine group on mouse neuroblastoma cells and chick ganglionic neurons in culture

A series of substances (designated CTQ compounds) with a guanidine group have been synthesized and tested for their ability to promote neuronal survival and neurite outgrowth. Mouse neuroblastoma clonal cell lines grown in serum-containing medium for 10 days as well as primary cultures of embryonic chicken ganglion neurons grown in serum-free defined medium for 1 or 2 days have been used for the experiments. Among the various CTQ compounds (CTQ1–CTQ20) tested, only CTQ8 exerted positive neurotrophic effects on these peripheral neuronal cells. At a concentration of 10⁻⁴ M, CTQ8 enhanced neuritogenesis of neuroblastoma cells. However, the most striking influence of CTQ8 was its promoting effect (6- to 10-fold) on the survival of chicken ciliary and dorsal root ganglionic neurons at concentrations ranging from 10⁻³ M to 5×10⁻⁴ M.     

A quantitative analysis of rat adrenal chromaffin tissue: Morphometric analysis at tissue and cellular level correlated with catecholamine content

A morphometric analysis of normal Wistar rat adrenal medulla following perfusion fixation and Araldite embedding, was correlated with catecholamine levels on fresh tissue, measured by high-performance liquid chromatography. The mean volume of whole adrenal is 13.2 mm³ and the mean medullary volume 1.3mm³. Volume density estimates showed that the medulla is composed of 63% chromaffin tissue with an adrenaline to noradrenaline storing cell ratio of 4.4:1. The vasculature occupies 20%, neuronal tissue 5% and interstitial tissues 12% of the medulla. A comparison was made of cell volumes, cell numbers and volume and surface density estimates of cytoplasmic organdies in adrenaline and noradrenaline storing cells. The mean cell volume of adrenaline storing cells at 1300 μm³ is larger than that of noradrenaline storing cells at 980 μm³. A single adrenal medulla contains4.4−5.7 × 10⁵ adrenaline cells and1.5−1.9 × 10⁵ noradrenaline cells. Chromaffin granules account for approximately 30% of the volume of the cytoplasm; the numerical density of granules at different sites in the cell was calculated for adrenaline cells. The volume density of mitochondria (4%) and the surface density of mitochondrial membranes (the ratio of outer to inner membrane being approximately 1:2.3) were similar in both cell types. Rough endoplasmic reticulum was the only organelle to show a significant difference in volume and surface density between the two cell types. Adrenaline storing cells have stacks of rough endoplasmic reticulum which have two to three times the surface and volume densities of that found diffusely scattered throughout noradrenaline cells. The adrenaline content of an adrenaline storing cell is0.14 × 10⁻⁶ μM and that of a granule 3.0 × 10⁻¹² or3.8 × 10⁻¹² μ moles depending on the method of calculation. The noradrenaline content of noradrenaline storing cells can only be calculated on the assumption that all noradrenaline is stored in this cell type though it is likely that some is contained within adrenaline cells. Based on this assumption the noradrenaline content is0.17 × 10⁻⁶μ moles per cell and5 × 10⁻¹² μ moles per granule. The present study provides baseline morphometric data on the rat adrenal medulla at tissue and cellular level correlated with amine levels in adrenaline and noradrenaline storing cells and granules.     

New modulated metallic macrocycles: Electrochemistry and their interaction with calf thymus DNA

New modulated pentacoordinate complexes [C₁₇H₃₄N₇O₂Cu]ClO₄ (5), [C₁₇H₃₄N₇O₂Co]ClO₄ (6), [C₁₇H₃₄N₇O₂Ni] ClO₄ (7) have been synthesized by the interaction of 1,8-dihydro-1,3,6,8,10,13 Cu(II) (2), Co(II) (3), Ni(II) (4) hexaazacyclotetradecane complexes and Hsalea N-(2-hydroxy benzyl)-2-amino-1-ethanol ligand (1). All the complexes have been characterized by infrared, electron paramagnetic resonance, ¹H and ¹³C nuclear magnetic resonance (NMR), 2D correlation spectroscopy NMR and ultraviolet–visible (UV–vis) spectroscopy. In all the complexes, the metal center is encapsulated by the Hsalea ligand in a pentacoordinate environment. Conductance measurements show that the complexes are ionic in nature. UV–vis absorption titration and viscometric studies have been carried out to ascertain the interaction of complexes 5 and 6 with calf thymus DNA (CT DNA). The experimental results suggest that complex 5 binds to CT DNA through partial intercalation of the aromatic ring into the base pair of DNA while complex 6 binds to CT DNA by electrostatic mode. The intrinsic binding constants K_b of complex 5 and 6 were found to be 6.8 × 10⁻⁵ M⁻¹ and 1.8 × 10⁻⁴ M⁻¹, respectively. The binding of complexes 5 and 6 with CT DNA has also been investigated by cyclic voltammetry.     

Acquisition of lipoproteins in the procyclic form of Trypanosoma brucei

The procyclic form of Trypanosoma brucei binds and internalizes bovine high density lipoprotein (HDL) particles in a saturable process; the binding and uptake of ¹²⁵I-labeled HDL are inhibited by excess unlabeled HDL. We calculated that each procyclic trypanosome exposes ≈1.0×10⁶ binding sites for bovine HDL, with an equilibrium dissociation constant (K_d) of ≈1.26×10⁻⁷ M. Uptake of HDL particles does not occur at 4°C. At 28°C, a significant amount of the internalized HDL particles were efficiently degraded through a process that is sensitive to the presence of 50 μM chloroquine. These results suggested that the uptake of HDL particles in procyclic T. brucei may occur via receptor mediated endocytosis, leading to proteolytic degradation of the particles in an acidic and endocytic compartment.     

The frequency of QAP2.1 is increased in psoriasis vulgaris patients

The heritage of psoriasis has a polygenic mode, the most essential antigens being Cw6,DR7,DQA1^*0201 in many ethnic groups. We have found a strong association between the high risk HLA haplotypes carrying DQA1^*0201 and psoriasis. Thus, the aim of this study was to further examine if the flanking promotor genes, URRs of DQ (QAP and QBP) are involved in the susceptibility to this disease. The series consisted of 62 patients and 50 control subjects and the PCR-SSO method was used. The frequency of the promoter gene QAP2.1 was significantly increased in the psoriatics (P_c=1.5×10⁻², RR=4.6) and the frequency of QAP4.1 was decreased in the patients group (P_c=3.9×10⁻²). The psoriasis risk allele DQA1^*0201 was associated always with QAP2.1, except once with QAP3.1.

: The combination of QAP2.1 and DQA1^*0201 is associated to psoriasis. Promotor region could exert its influence by gene expression or functionally through different inducibility by cytokines.     

Lithium discriminates between muscarinic receptor subtypes on guinea pig hippocampal neurons in vitro

In CA3 pyramidal neurons of guinea pig hippocampal slices an outward current activated by the GABA_B agonist, baclofen (0.3 μM, I_bac) was reduced by low concentrations of carbachol (Cch, 0.1–0.3 μM). The effect of Cch desensitized suggesting that the receptor subtype involved in this muscarinic effect of Cch was of the M₁ subtype. The receptor subtype was also characterized by its equilibrium dissociation constant for pirenzepine (10 nM) as an M₁ receptor. Li⁺ applied extracellularly (1 mM) or intracellularly blocked the suppression of I_bac by Cch without affecting the Cch blockade of a current termed I_AHP, which is mediated by M₂ receptors. While the effect of intracellular Li⁺ application was immediate, it developed very slowly with extracellular application. Since Li⁺-salts are used effectively in the treatment of mania and depression, the selective effect of Li⁺ on M₁-mediated muscarinic neurotransmission might be important for the cholinergic hypothesis of affective disorders.     

Human extracellular proteins display a different pattern of local sequence similarity with the four classes of human T-cell receptor V-regions than foreign proteins and human intracellular proteins: a preliminary report

A pool of 110 randomly selected/generated amino acids sequences was used to perform specific local sequence similarity alignment analysis with the pool of 279 reported sequences of human T-cell receptor (TCR) V-regions. The 110 analyzed sequences were divided, according to their origin and nature, into six protein groups, as: human intracellular (hi), extracellular/transmembrane (he) and extracellular adhesive matrix (ha) proteins, ‘average' human proteins (hum), proteins of non-human origin (nhum) and randomly generated quasi-protein sequences (r). These sequences were decomposed into all their overlapping 11-mer segments, generating a total of 56 836 derived peptides (at least 8000 per group). Each derived peptide was aligned with the 279 human TCR V-regions and assigned to the category (-like, β-like, γ-like or δ-like) corresponding to the class (V, Vβ, Vγ or Vδ) of the V-region encompassing the most similar segment, as determined by the performed similarity-search. The six protein groups were found to differ significantly in their distribution of derived peptides among the four categories. According to the binomial tests results, human proteins from the extracellular compartment (he, ha) comprise a higher proportion of δ-like segments (P=2.3×10⁻² and P<10⁻⁸, respectively) than the ‘average' human proteins (hum). In addition, and in accordance with this finding, proteins that are normally not found in that topological compartment comprise a lower proportion of δ-like peptides (P=1.4×10⁻⁵ and P<10⁻⁸ for groups nhum and hi, respectively) than the ‘average' human proteins (hum). In contrast, these proteins comprise a higher proportion of γ-like segments (P=8.3×10⁻³, P=1.4×10⁻³ and P=1.7×10⁻⁴, for groups r, nhum and hi, respectively) than the ‘average' human proteins (hum). These findings indicate significant differences between proteins encountered in the extracellular compartment—that are normally immunologically tolerated—and those the presence of which is usually non-tolerated. The results suggest that the discrimination and the reaction of the human immune network to proteins found in the extracellular compartment correlate with the proteins' pattern of preferential local sequence similarity with the Vγ and Vδ classes of human TCR V-regions, implying a specific and an important role of γδ-cells in the maintenance of the immune homeostasis. Whether this implication represents a rule associated with self-tolerance, will be investigated by future analyses.     

Biomechanics of the saphenous artery and vein in spontaneous hypertension in rats

Incremental compliance and distensibility of certain muscular arteries were recently reported to be normal or slightly increased in hypertension at the same pressure levels. In this work biomechanical properties of isolated perfused and superfused veins and large muscular arteries from saphenous bed from male spontaneously hypertensive (SHR) and Wistar–Kyoto (WKY) rats were compared in vitro. Outer diameter of cylindrical vessel segments was measured and intraluminal pressure (IP) was changed cyclically. We found larger contractile response to methoxamine (1.06×10⁻⁵ mol/l) in SHR arteries compared to WKY (active strain e.g. at 100 mmHg IP: 7.12±4.1 vs 0.35±0.46%). Resting incremental distensibility was higher (e.g. 100 mmHg IP: 3.4±0.4×10⁻⁶ vs 1.2±0.3×10⁻⁷ m²/N), elastic modulus lower (e.g. 100 mmHg IP: 3.7±0.6×10⁵ vs 27±7.6×10⁵ N/m²) in the arteries from SHR in pressure range of 60–110 mmHg. After papaverine administration (2.8×10⁻⁴ mol/l) the artery became more rigid, thus the increased incremental elasticity of SHR artery might be due to the enhanced smooth muscle tone. However, compared at in vivo pressure levels the differences were negligible suggesting a shift in the elastic parameters toward the higher operation pressures. Saphenous vein of SHR had larger diameter, than that of WKY, while in the wall thicknesses no difference were found (therefore external radius-wall thickness ratio was larger, e.g. at 6 mmHg IP: 15.9±3.0 vs 8.1±0.7). Consequently, lumen capacity of the vein was also higher in SHR, however, elastic parameters did not exhibit significant differences. We conclude that pressure-distensibility curve of muscular type arteries like SHR saphenous artery is shifted to higher pressure levels compared with that of normotensive controls. This shift is due to the enhanced smooth muscle contractility. The unchanged elasticity of veins suggests that the arterial deformations in SHR are not primary but secondary alterations.     

Improvement in the basic technology of electrofusion for generation of antibody-producing hybridomas

In order to define the optimum conditions of electrofusion technique for the generation of antibody-producing hybridomas, mouse spleen cells or EBV-transformed human B cells were fused with mouse myeloma cells (SP2/0) or human fusion partner cells (KR-4 or KR-12), respectively, by electric field pulse under various conditions. The results confirm reports that the presence of both Ca²⁺ and Mg²⁺ in fusion medium and pretreatment of mixed cells with proteases improved hybridoma yield. Moreover, the presence of liposome or hydrophobic protein in the fusion medium greatly enhanced the yield. Under optimum conditions, hybridoma yields of mouse cells and human cells were 2.5 × 10⁻⁴ and 1 ×10⁻⁴, respectively. These efficiencies were about ten times higher than those obtained by the conventional polyethylene glycol technique. Microscopic observation of the fusion-process revealed that in a human cell system 20%–50% of the cells were physically fused, although only one in 5000 physically fused human cells grew as a hybridoma after hypoxanthine-aminopterin-thymidine selection.     

Linkage of low and high affinity anti-fluorescein idiotype families

Data presented in this study describes the isolation and characterization of two anti-fluorescein (Fl) hybridoma proteins 3–24 and 12–40, both IgG₁, with a K_a = 2.8 and 3.4 × 10⁶ M⁻¹, respectively, at 37°C. These clones inhibited (6.8 ± 2.8 − 20.8 ± 0.6% at l μg/well) the idiotype-anti-idiotype interactions (IAII) of anti-Fl clones 3–13 and 3–17, which define a previously described low affinity idiotype family. Antibodies 3–24 and 12–40 also inhibited (45.0 ± 3.0 and 61.3 ± 5.6%, respectively, at 1 μg/well) an IAII denfied by a high affinity (K_a = 5.2 ± 1.5 × 10⁹ M⁻¹ at 37°C) anti-Fl clone, 4-4. Hybridoma proteins 3–13 and 3–17 possess similar affinities for Fl (K_a = 3.8 ± 5.1 and 5.9 ± 4.0 × 10⁴ M⁻¹) and are known to be idiotypically unrelated to clone 4-4. While 3–24 and 12–40 appeared very similar, non-identity of their active sites was established by heterologous idiotypic inhibitions, fine specificity of binding and spectral measurements (Q_max and λ_max) of bound Fl. All IAII (3–13, 3–17, 9–40 and 4-4) were inhibited>80% by the presence of 10⁻⁴M F1 or F1-BSA, In addition, four intermediate affinity (6.0 × 10⁶ K_a 5.3 × 10⁸ M⁻¹) anti-FI clones, comprising a second previously described idiotype family (designated the 9–40 family) were further analyzed. Inhibition of the 9–40 IAII by all heterologous proteins in the 9–40 family (except clone 5–27), and clones 3–24, 12–40 and 4-4 ranged from 87.7 ± 1.3 to 95.4 ± 1.0% at 1μg/well. Titration of the 9–40 IAII inhibition by antibodies 9–40, 3–24, 12–40 or 4-4 generated essentially superimposable profiles. In reciprocal inhibition experiments, using the 4-4 IAII, clones 3–24, 12–40, 9–40 and 4-4 gave distinct idiotypic titration patterns. Thus, members of the 9–40 family, 3–24 and 12–40 were more closely related to intermediate affinity clone 9–40 than high affinity clone 4-4. Finally all members of the 9–40 family also significantly inhibited both the 3–13 and 3–17 IAII (11.8 ± 3.1 − 32.9 ± 6.1 at 1 μg/well) and gave distinct idiotypic inhibition profiles. Clones 3–24 and 12–40, characterized in this report, and the 9–40 family provide linkage between idiotypically distinct anti-Fl hybridoma proteins differing in affinity by> 20,000-fold. This linkage provides a greater span in affinity, than in all previously reported idiotypic families, within restricted or unrestricted systems.     

Permeability of amalgam restorative materials

The beneficial effect of fluoride-containing amalgam in preventing recurrent dental caries depends on the ability of the material to deliver fluoride (F). A two-chamber diffusion cell has been employed to monitor the diffusion of F in freshly prepared amalgam sections (membranes) as well as in amalgam sections stored in F solution for 15 d. The diffusion of ¹²⁵I was also monitored, as a reference. Five and ten successive measurements at 72 h intervals were made on the fresh and stored amalgam specimens, respectively. The average diffusion coefficient, D, of F and ¹²⁵I in fresh amalgam was 2.39 × 10⁻¹⁰ and 1.85 × 10⁻¹⁰ cm²/s, respectively. For stored amalgam, the average D of F during a 30 d experiment was 1.35 × 10⁻¹⁰ cm²/s. The average D of F in stored amalgam, during the first 15 d of the experiment, was 31 % less than in fresh amalgam (p < 0.01). A decline in the diffusion process was observed during the course of the experiments. During 15 d diffusion in fresh amalgam and 30 d diffusion in stored amalgam the cumulative diffused F were 0.79 and 0.88% of the F in the source. SEM findings revealed the deposition of corrosion products on amalgam stored for 3 months in 0.19% F solution.     

Dihydropyridine-sensitive calcium currents in bipolar cells of salamander retina are inhibited by reductions in extracellular chloride

Dihydropyridine-sensitive calcium currents (I_Ca) in photoreceptors are unusual in that they can be inhibited by reductions in extracellular chloride. The present study examined whether I_Ca in retinal bipolar cells, which as in photoreceptors mediates sustained neurotransmission, is also inhibited by reductions in chloride. Nystatin-perforated patch, whole cell recordings were obtained from bipolar cells in a retinal slice preparation of larval tiger salamander. In the presence of Ba²⁺, voltage steps above −40 mV evoked sustained inward currents, which were enhanced by the dihydropyridine, (−)BayK8644, and inhibited by nisoldipine. Similar to photoreceptors, replacing Cl⁻ with gluconate or CH₃SO₄ inhibited bipolar cell I_Ca and produced a negative shift in the current/voltage relationship. Thus, sensitivity to Cl⁻ may be a more general property of L-type Ca²⁺ channel subtypes that mediate sustained neurotransmission.     

Chemiluminescence in Human Whole Blood: Modulation by the Cocarcinogens Phorbol Diester and Polychlorobiphenyls

A human whole blood chemiluminescence (CL) assay was established using zymosan as cell activator. Aroclor 1254 was found to inhibit this CL response in a direct linear relation to its concentration, (50% inhibitory dose, (ID₅₀) equal to 5 × 10^-4 M) in diluted blood samples of 10 normal human subjects. In comparison the ID₅₀ of other inhibitors was 1.3 × 10^-3 M for ethylenediamine tetraacetic acid, 3.3 × 10^-3 M for ascorbic acid, 4 × 10^-3 M for reduced glutathione, 1.2 × 10^-3M for ethanol, 2.5 × 10^-1 for methanol and 3.7 × 10^-1 M for dimethyl sulfoxide. Using 12-o-tetradecanoyl-phorbol-13-acetate (TPA) as cell activator the CL response was likewise inhibited by Aroclor 1254 with an ID₅₀ of 4.5 × 10^-4 M. However, it was found that Aroclor 1254 alone has a stimulatory CL effect on otherwise unactivated cells. To compare the mechanisms involved in the CL elicited by the three stimulants zymosan, TPA and Aroclor 1254, the CL signal was measured in the presence of cytochalasin B. Cytochalasin B inhibited zymosan-induced CL, had a smaller inhibitory effect on TPA-induced CL but it could augment the CL response initiated by Aroclor 1254. This pattern of responses implicates Aroclor 1254 in the activation of eicosanoid metabolism as it matches the differential responses reported for arachidonic acid.     

Mechanism of histamine-induced calcium efflux from cultured bovine adrenal chromaffin cells: possible involvement of an Na/Ca exchange mechanism

The effect of stimulation of the histamine receptor on Ca²⁺ mobilization in cultured bovine adrenal chromaffin cells was examined. Histamine (10⁻⁵ M) increased the intracellular free Ca²⁺ ([Ca²⁺]_i) to a peak in the presence or absence of extracellular Ca²⁺, followed by decrease with time. Histamine (10⁻⁸–10⁻⁵ M) also stimulated ⁴⁵Ca²⁺ efflux from cultured bovine adrenal chromaffin cells in a concentration dependent manner. Its stimulatory effect on ⁴⁵Ca²⁺ efflux was inhibited by the specific histamine H₁ receptor antagonist mepyramine. The increase in histamine-stimulated ⁴⁵Ca²⁺ efflux was inhibited by deprivation of extracellular Na⁺ and by the Na⁺/Ca²⁺ exchange inhibitor amiloride. In addition, histamine stimulated ²²Na⁺ influx into the cells, and this action was inhibited by amiloride. These results suggest that stimulation of the histamine H₁ receptor regulates Na⁺/Ca²⁺ exchange in cultured bovine adrenal chromaffin cells.     

Lack of effect of opioid compounds on angiotensin II responses of bovine adrenal medullary cells

Angiotensin II (10 nM) increased basal adrenaline and noradrenaline secretion from cultured bovine adrenal chromaffin cells by 2.5- to 3-fold and 4- to 6-fold, respectively, and stimulated basal accumulation of inositol phosphates more than 2-fold. Etorphine and diprenorphine in the range 10⁻⁹ to 10⁻⁵ M had no effect on the catecholamine secretion induced by angiotensin II, and, at 10⁻⁸ and 10⁻⁵ M, had no effect on angiotensin II-induced inositol phosphate accumulation. The functions of adrenal medullary opioid receptors remain to be determined.     

Affinity of purified thrombin or antithrombin III for two insoluble anticoagulant polystyrene derivatives: I. In vitro adsorption studies

In previous papers, we described insoluble polystyrene derivatives which exhibit a heparin-like antithrombic activity in plasma. In order to ascertain the heparin-like mechanism of this activity we have studied the interactions of thrombin and antithrombin III with two polymers of this series: sulphonated polystyrene and sulphonate-glutamic acid sulphonamide polystyrene. The adsorption was measured using purified enzyme and enzyme inhibitor and polymer beads whose average diameter was about 25 μm. The maxima of adsorption approximately correspond to a monolayer of protein. The results are discussed with respect to the most common isotherms used in chemisorption and the affinities of the enzyme and its inhibitor for both materials are evaluated: k_T- 10⁷(M/I)⁻¹, k_AT- 3.10⁵(M/I)⁻¹.