The rise in concentration of free Ca2+ and of pH provides sequential, synergistic signals for secretion in antigen-stimulated rat basophilic leukemia (RBL-2H3) cells

Ag stimulation of rat basophilic leukemia (RBL-2H3) cells results in hydrolysis of inositol phospholipids, a transient increase in concentration of cytosol Ca2+ [( Ca2+]i), a gradual increase in cytosolic pH (pHi) and the activation of protein kinase C. To determine whether all these changes serve as signals for secretion, studies were conducted with cells permeabilized with streptolysin O in which pHi and [Ca2+]i could be varied independently of each other and enzyme activities could be manipulated. At resting pHi (approximately 7.0) and [Ca2+]i (0.1 microM), the permeabilized cells showed little secretory response to Ag. At resting pHi, elevated levels of Ca2+ (0.33 microM) were required for maximal secretory response to Ag. At a pHi of 7.4, however, 0.1 microM [Ca2+]i was sufficient to sustain near maximal responses to Ag. Therefore, a small increase of [Ca2+]i to 0.33 microM was required to initiate secretion, but once the pHi was elevated secretion could be sustained at near basal levels of [Ca2+]i. Since elevating the [Ca2+]i and pHi, by themselves promoted little secretion, another potentiating signal must have been generated by antigen stimulation. This signal was possibly transduced via hydrolysis of inositol phospholipids and protein kinase C. Even with an elevated [Ca2+]i (0.33 microM) the hydrolysis of the phospholipids and secretion stimulated by Ag were inhibited by guanosine 5'(2-O-thio)diphosphate and neomycin. Furthermore, both protein-kinase C and the secretory response to Ag were lost after permeabilized cells were washed but both were retained if cells were exposed to PMA before permeabilization.

Studies of protein kinase C in the rat basophilic leukemia (RBL-2H3) cell reveal that antigen-induced signals are not mimicked by the actions of phorbol myristate acetate and Ca2+ ionophore

Exogenous activators of protein kinase C such as PMA in combination with a Ca2+ ionophore (A23187), cause secretion in rat basophilic (RBL-2H3) cells,but they do so through stimulatory signals that are not the same as those generated by Ag or oligomers of IgE. On the one hand, the synergy between PMA and A23187 and the suppression of Ag-mediated signals (hydrolysis of inositol phospholipids and rise in concentration of cytosolic Ca2+) by PMA were totally dependent on protein kinase C. The loss of synergistic and inhibitory actions of PMA, for example, correlated with the loss of protein kinase C (as determined by immunoblotting techniques) when cells were continuously exposed to PMA. Furthermore, the permeabilization of RBL-2H3 cells resulted in the loss of both protein kinase C and the inhibitory action of PMA, but both were retained if cells were exposed to PMA before permeabilization Ag-induced secretion, on the other hand, was not as dependent on the presence of protein kinase C. The potent inhibitor of this enzyme, staurosporine, which blocked completely the secretory response to the combination of PMA and A23187, did not inhibit Ag-induced secretion except at concentrations (greater than 10 nM) that inhibited Ag-stimulated hydrolysis of inositol phospholipids as well. Also RBL-2H3 cells still showed some secretory-response (approximately 25% of normal) to Ag when cells were depleted (greater than 98%) of protein kinase C by prolonged treatment with PMA. Previous studies have indicated that the secretory response to PMA and A23187 is much lower than that elicited by Ag when the concentrations of stimulants were matched to give the same increase in concentrations of cytosolic Ca2+.

The rise in concentration of free Ca2+ and of pH provides sequential, synergistic signals for secretion in antigen-stimulated rat basophilic leukemia (RBL-2H3) cells

Ag stimulation of rat basophilic leukemia (RBL-2H3) cells results in hydrolysis of inositol phospholipids, a transient increase in concentration of cytosol Ca2+ [( Ca2+]i), a gradual increase in cytosolic pH (pHi) and the activation of protein kinase C. To determine whether all these changes serve as signals for secretion, studies were conducted with cells permeabilized with streptolysin O in which pHi and [Ca2+]i could be varied independently of each other and enzyme activities could be manipulated. At resting pHi (approximately 7.0) and [Ca2+]i (0.1 microM), the permeabilized cells showed little secretory response to Ag. At resting pHi, elevated levels of Ca2+ (0.33 microM) were required for maximal secretory response to Ag. At a pHi of 7.4, however, 0.1 microM [Ca2+]i was sufficient to sustain near maximal responses to Ag. Therefore, a small increase of [Ca2+]i to 0.33 microM was required to initiate secretion, but once the pHi was elevated secretion could be sustained at near basal levels of [Ca2+]i. Since elevating the [Ca2+]i and pHi, by themselves promoted little secretion, another potentiating signal must have been generated by antigen stimulation. This signal was possibly transduced via hydrolysis of inositol phospholipids and protein kinase C. Even with an elevated [Ca2+]i (0.33 microM) the hydrolysis of the phospholipids and secretion stimulated by Ag were inhibited by guanosine 5'(2-O-thio)diphosphate and neomycin. Furthermore, both protein-kinase C and the secretory response to Ag were lost after permeabilized cells were washed but both were retained if cells were exposed to PMA before permeabilization.

Studies of protein kinase C in the rat basophilic leukemia (RBL-2H3) cell reveal that antigen-induced signals are not mimicked by the actions of phorbol myristate acetate and Ca2+ ionophore

Exogenous activators of protein kinase C such as PMA in combination with a Ca2+ ionophore (A23187), cause secretion in rat basophilic (RBL-2H3) cells,but they do so through stimulatory signals that are not the same as those generated by Ag or oligomers of IgE. On the one hand, the synergy between PMA and A23187 and the suppression of Ag-mediated signals (hydrolysis of inositol phospholipids and rise in concentration of cytosolic Ca2+) by PMA were totally dependent on protein kinase C. The loss of synergistic and inhibitory actions of PMA, for example, correlated with the loss of protein kinase C (as determined by immunoblotting techniques) when cells were continuously exposed to PMA. Furthermore, the permeabilization of RBL-2H3 cells resulted in the loss of both protein kinase C and the inhibitory action of PMA, but both were retained if cells were exposed to PMA before permeabilization Ag-induced secretion, on the other hand, was not as dependent on the presence of protein kinase C. The potent inhibitor of this enzyme, staurosporine, which blocked completely the secretory response to the combination of PMA and A23187, did not inhibit Ag-induced secretion except at concentrations (greater than 10 nM) that inhibited Ag-stimulated hydrolysis of inositol phospholipids as well. Also RBL-2H3 cells still showed some secretory-response (approximately 25% of normal) to Ag when cells were depleted (greater than 98%) of protein kinase C by prolonged treatment with PMA. Previous studies have indicated that the secretory response to PMA and A23187 is much lower than that elicited by Ag when the concentrations of stimulants were matched to give the same increase in concentrations of cytosolic Ca2+.

Distribution of haptoglobin phenotypes in oesophageal and gastric cancer

Haptoglobin (Hp) phenotypes were studied in 72 oesophageal and 104 gastric cancer patients and compared with 100 healthy controls to see if there is any association between oesophageal and gastric cancer and haptoglobin type. There was a significantly increased frequency of Hp 2-1 (59.7%) and Hp 2-2 (91.3%) in oesophageal and gastric cancer patients. Our results suggest that genetic factors play a role in the aetiology and pathogenesis of gastrointestinal tract malignancy.

Receptor-mediated release of inositol 1,4,5-trisphosphate and inositol 1,4-bisphosphate in rat basophilic leukemia RBL-2H3 cells permeabilized with streptolysin O

Antigen-mediated exocytosis in intact rat basophilic leukemia (RBL-2H3) cells is associated with substantial hydrolysis of membrane inositol phospholipids and an elevation in concentration of cytosol Ca2+ ([ Ca2+i]). Paradoxically, these two responses are largely dependent on external Ca2+. We report here that cells labeled with myo-[3H]inositol and permeabilized with streptolysin O do release [3H]inositol 1,4,5-trisphosphate upon stimulation with antigen or guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) at low (less than 100 nM) concentrations of free Ca2+. The response, however, is amplified by increasing free Ca2+ to 1 microM. The subsequent conversion of the trisphosphate to inositol 1,3,4,5-tetrakisphosphate is enhanced also by the increase in free Ca2+. Although [3H]inositol 1,4,5-trisphosphate accumulates in greater amounts than is the case in intact cells, [3H]inositol 1,4-bisphosphate is still the major product in permeabilized cells even when the further metabolism of [3H]inositol 1,4,5-trisphosphate is suppressed (by 77%) by the addition of excess (1000 microM) unlabeled inositol 1,4,5-trisphosphate and the phosphatase inhibitor 2,3-bisphosphoglycerate. It would appear that either the activity of the membrane 5-phosphomonoesterase allows virtually instantaneous dephosphorylation of the inositol 1,4,5-trisphosphate under all conditions tested or both phosphatidylinositol 4-monophosphate and the 4,5-bisphosphate are substrates for the activated phospholipase C. The latter alternative is supported by the finding that permeabilized cells, which respond much more vigorously to high (supraoptimal) concentrations of antigen than do intact RBL-2H3 cells, produce substantial amounts of [3H]inositol 1,4-bisphosphate before any detectable increase in levels of [3H]inositol 1,4,5-trisphosphate.

Targeting adriamycin to tumour cells by means of an affinity ligand; a model system for drug delivery

Actively migrating tumour cells possess the proteolytic enzyme guanidinobenzoatase (GB) in an uninhibited form. This enzyme has been used as a target for the delivery of adriamycin to invasive tumour cells in frozen sections. An adriamycin-agmatine complex has been prepared which act as a competitive inhibitor of GB. Competition experiments have demonstrated that the adriamycin-agmatine complex competes with 9-aminoacridine for the active centre of GB associated with invasive tumour cells, located in the lymph nodes and in squamous cell carcinoma of the oral cavity. The technique described should be generally applicable to the targeting of drugs to cells.

Formation of inositol 1,4,5-trisphosphate and inositol 1,3,4-trisphosphate from inositol 1,3,4,5-tetrakisphosphate and their pathways of degradation in RBL-2H3 cells

Previous studies with antigen-stimulated rat basophilic leukemia (RBL-2H3) cells indicated the formation of multiple isomers of each of the various categories of inositol phosphates. The identities of the different isomers have been elucidated by selective labeling of [3H]inositol 1,3,4,5-tetrakisphosphate with [32P]phosphate in the 3'-or 4',5'-positions and by following the metabolism of different radiolabeled inositol phosphates in extracts of RBL-2H3 cells. We report here that inositol 1,3,4,5-tetrakisphosphate, when incubated with the membrane fraction of extracts of RBL-2H3 cells, was converted to inositol 1,4,5-trisphosphate and inositol 1,3,4-trisphosphate. Further dephosphorylation of the inositol polyphosphates proceeded rapidly in whole extracts of cells, although the process was significantly retarded when ATP (2 mM) levels were maintained by an ATP-regenerating system. The degradation of inositol 1,4,5-trisphosphate proceeded with the sequential formation of inositol 1,4-bisphosphate, the inositol 4-monophosphate (with smaller amounts of the 1-monophosphate), and finally inositol. Inositol 1,3,4-trisphosphate, on the other hand, was converted to inositol 1,3-bisphosphate and inositol 3,4-bisphosphate and subsequently to inositol 4-monophosphate and inositol 1-monophosphate (stereoisomeric forms were undetermined). The possible implications of the apparent interconversion between inositol 1,4,5-trisphosphate and inositol 1,3,4,5-tetrakisphosphate in regulating histamine secretion in the RBL-2H3 cells are discussed.

Synthesis, receptor binding, and tissue distribution of (17 alpha,20E)- and (17 alpha,20Z)-21-[125I]iodo-19-norpregna-1,3,5(10), 20-tetraene-3,17-diol

The isomeric (17 alpha,20E)- and (17 alpha,20Z)-(iodovinyl)estradiol derivatives 3 and 6, and their no-carrier-added (nca) [125I]iodovinyl analogues, were tested for their relative target tissue retention and binding affinity for the estrogen receptor. The (iodovinyl)estradiols 3 and 6 were prepared via destannylation of the (17 alpha,20E)- and (17 alpha,20Z)-tributylstannyl precursors 2 and 4 with retention of configuration. Selective formation of the E or Z isomers 2 and 4 during the reaction of 17 alpha-ethynylestradiol 1a with tri-n-butyltin hydride was controlled by the presence or absence of the catalyst, the polarity of the solvent, and the reaction temperature. The nca [125I]iodovinyl analogues [125I]-3a and [125I]-6a were obtained in good radiochemical yield and high purity by treatment of 2a and 4a with [125I]NaI in the presence of H2O2 and chloroamine-T, respectively. Of the two isomeric iodovinyl derivatives 3 and 6, the 20Z isomer 6a exhibited the highest receptor binding affinity and the [125I]-6a gave the highest in vivo receptor-mediated target tissue uptake.

Assessment of IgE-receptor function through measurement of hydrolysis of membrane inositol phospholipids. New insights on the phenomena of biphasic antigen concentration-response curves and desensitization

Previous studies have shown that hydrolysis of membrane inositol phospholipids in rat basophilic leukemia (RBL-2H3) cells depended on the rate and extent of the aggregation of receptors of IgE. This response was used as an experimental probe to study the role of IgE receptors in initiating stimulatory and inhibitory processes within the cell. The response was amplified markedly by increasing the concentration of external Ca2+ from 0 to 1 mM, but the concentration required to support half-maximal response varied from less than 0.1 mM for the most potent cross-linking reagent, DNP24BSA (24 molecules of DNP attached to 1 molecule of BSA) to 0.5 mM for the least potent reagent, aggregated OVA. The dependency of phosphoinositide hydrolysis on external Ca2+ was reduced to zero once hydrolysis of inositol phospholipids was underway but secretion of histamine remained totally dependent on the presence of 0.5 to 1 mM external Ca2+. The stimulatory response persisted as long as receptors remained aggregated but it was modulated by a biochemical process, possibly the activation of protein kinase C, that targeted specifically aggregated receptors, or an associated protein. For example, when cells had become desensitized to high concentrations of one Ag, a normal response could be evoked with a second Ag. Also cells that had become desensitized could be reactivated by permeabilizing the cells. Interestingly, bell-shaped Ag dose-response curves, which were characteristic for both the phosphoinositide and secretory responses, were transformed to sigmoid-shaped curves once cells were permeabilized and dialyzed.

Assessment of IgE-receptor function through measurement of hydrolysis of membrane inositol phospholipids. New insights on the phenomena of biphasic antigen concentration-response curves and desensitization

Previous studies have shown that hydrolysis of membrane inositol phospholipids in rat basophilic leukemia (RBL-2H3) cells depended on the rate and extent of the aggregation of receptors of IgE. This response was used as an experimental probe to study the role of IgE receptors in initiating stimulatory and inhibitory processes within the cell. The response was amplified markedly by increasing the concentration of external Ca2+ from 0 to 1 mM, but the concentration required to support half-maximal response varied from less than 0.1 mM for the most potent cross-linking reagent, DNP24BSA (24 molecules of DNP attached to 1 molecule of BSA) to 0.5 mM for the least potent reagent, aggregated OVA. The dependency of phosphoinositide hydrolysis on external Ca2+ was reduced to zero once hydrolysis of inositol phospholipids was underway but secretion of histamine remained totally dependent on the presence of 0.5 to 1 mM external Ca2+. The stimulatory response persisted as long as receptors remained aggregated but it was modulated by a biochemical process, possibly the activation of protein kinase C, that targeted specifically aggregated receptors, or an associated protein. For example, when cells had become desensitized to high concentrations of one Ag, a normal response could be evoked with a second Ag. Also cells that had become desensitized could be reactivated by permeabilizing the cells. Interestingly, bell-shaped Ag dose-response curves, which were characteristic for both the phosphoinositide and secretory responses, were transformed to sigmoid-shaped curves once cells were permeabilized and dialyzed.

The inhibition of a tumour cell surface protease in vivo and its re-activation by oxidation

Colonic tumour cells possess a cell surface protease capable of binding 9-aminoacridine to its active centre, thus locating cells when viewed under a fluorescence microscope. In vivo and in frozen sections, the enzyme is masked by a protein inhibitor. This inhibitor can be displaced by formaldehyde fixation of the tissue and then replaced by adding a fresh extract of colon or lung tissue. The inhibitor is modified by oxidation; provided by air, oxidized glutathione or potassium permanganate, resulting in a change in conformation in the inhibitor and this then results in the enzyme binding the fluorescent probe. The effect of oxidation can be reversed by dithiothreitol. It is proposed that these changes are brought about by a disulphide exchange acting on the inhibitor which indirectly controls the activity of the cell surface enzyme in vivo. The steps described above can be conveniently followed on sections of tissue mounted on a microscope slide; this has the advantage that the same cells can be monitored during a sequence of reactions. It is believed that these techniques could well be applied to other enzyme systems than the tumour protease described in this study.

Identification of variants of the basophilic leukemia (RBL-2H3) cells that have defective phosphoinositide responses to antigen and stimulants of guanosine 5'-triphosphate-regulatory proteins

Antigen immunoglobulin E-mediated secretion of histamine from RBL-2H3 cells is associated with substantial hydrolysis of membrane inositol phospholipids and a rise in the concentration of cytosol Ca2+ (calcium signal). Such responses differed among cloned variant lines of the RBL-2H3 cell line from undetectable (1A3 bromodeoxyuridine-resistant (BUDRR), 2B1 BUDRR, and 1B3 BUDRR lines) to about 80% of those in the parent RBL-2H3 cells. In all but one line (1B3 thioguanine-resistant (TgR)), the intensities of the phosphoinositide response and of the calcium signal were correlated with the secretory response. The 1B3 TgR line had no detectable calcium signal (as measured by quin 2 fluorescence or uptake of 45Ca2+) but paradoxically showed modest rates of hydrolysis of inositol phospholipids and of secretion. The responses of the 1B3 TgR line were, however, dependent on the presence of external Ca2+ ions. The induction of secretion with antigen, therefore, was invariably associated with the hydrolysis of inositol phospholipids, but it was not necessarily associated with a change in concentration of cytosol Ca2+. All antigen unresponsive clones could secrete when synergistic signals were induced by exposure to the Ca2+ -ionophore, A23187 and the phorbol ester, 12-O-tetradecanoylphorbol 13-acetate. These lines, otherwise, had immunoglobulin E receptors and had no obvious defect in their capacity to synthesize the inositol phospholipids or in their phenotypic expression of phospholipase C as measured in cell extracts. One finding of possible relevance to the role of guanosine 5'-triphosphate-regulatory proteins in the activation of phospholipase C was the inability of one antigen-nonresponsive line to respond to NaF (in intact cells) or to guanosine 5'-(3-O-thio)triphosphate (in electrically permeabilized cells).

Identification of variants of the basophilic leukemia (RBL-2H3) cells that have defective phosphoinositide responses to antigen and stimulants of guanosine 5'-triphosphate-regulatory proteins

Antigen immunoglobulin E-mediated secretion of histamine from RBL-2H3 cells is associated with substantial hydrolysis of membrane inositol phospholipids and a rise in the concentration of cytosol Ca2+ (calcium signal). Such responses differed among cloned variant lines of the RBL-2H3 cell line from undetectable (1A3 bromodeoxyuridine-resistant (BUDRR), 2B1 BUDRR, and 1B3 BUDRR lines) to about 80% of those in the parent RBL-2H3 cells. In all but one line (1B3 thioguanine-resistant (TgR)), the intensities of the phosphoinositide response and of the calcium signal were correlated with the secretory response. The 1B3 TgR line had no detectable calcium signal (as measured by quin 2 fluorescence or uptake of 45Ca2+) but paradoxically showed modest rates of hydrolysis of inositol phospholipids and of secretion. The responses of the 1B3 TgR line were, however, dependent on the presence of external Ca2+ ions. The induction of secretion with antigen, therefore, was invariably associated with the hydrolysis of inositol phospholipids, but it was not necessarily associated with a change in concentration of cytosol Ca2+. All antigen unresponsive clones could secrete when synergistic signals were induced by exposure to the Ca2+ -ionophore, A23187 and the phorbol ester, 12-O-tetradecanoylphorbol 13-acetate. These lines, otherwise, had immunoglobulin E receptors and had no obvious defect in their capacity to synthesize the inositol phospholipids or in their phenotypic expression of phospholipase C as measured in cell extracts. One finding of possible relevance to the role of guanosine 5'-triphosphate-regulatory proteins in the activation of phospholipase C was the inability of one antigen-nonresponsive line to respond to NaF (in intact cells) or to guanosine 5'-(3-O-thio)triphosphate (in electrically permeabilized cells).

Regioselective A-ring iodination of estradiol diacetates

Treatment of estrone or estradiol acetate with thallium trifluoroacetate in TFA and subsequent reaction with KI gave the 2-iodoestrogens as the major product. In the case of estradiol diacetate, treatment of the thallation product with [125I]NaI, using the same reaction conditions, gave exclusively the 2-iodo isomer. Thus, regioselectivity combined with rapidity, renders this procedure particularly suitable for A-ring radioiodination of estradiol with short-lived isotopes.

Some studies on the release of histamine from mast cells treated with d-tubocurarine

d-Tubocurarine (dTc) released histamine in non-cytotoxic fashion from peritoneal mast cells of the rat, mouse and hamster. The response was similar to that evoked by other cationic liberators such as compound 48/80 and polylysine in that it was extremely rapid and enhanced by calcium-deprivation at suboptimal concentrations of secretagogue. Tissue mast cells obtained by enzymic dissociation of the heart, lung and mesentery of the rat and guinea pig were unreactive or hyporesponsive to the effect of dTc. The compound liberated only very small amounts of histamine from isolated preparations of perfused guinea pig heart but significantly increased the rate and contractility of the heart. These results are discussed in terms of the general functional heterogeneity of mast cells from different locations.

Comparison of the histamine-releasing action of substance P on mast cells and basophils from different species and tissues

The action of the neuropeptide substance P as a histamine-releasing agent has been compared in histamine-containing cells from a variety of different tissues and species. Peritoneal mast cells from rat, mouse and hamster but not human cells gave a concentration-dependent release of histamine in response to substance P. Release was greater in the absence than in the presence of calcium in the extracellular medium. Mast cells from rat mesentery, lung and heart released histamine in response to substance P, but heart mast cells responded only weakly. All guinea-pig mast cells and histamine-containing cells from human tissues did not give any substantial substance-P-induced release of histamine. The data provides further evidence for the functional heterogeneity of histamine-containing cells.

Definition of essential sequences and functional equivalence of elements downstream of the adenovirus E2A and the early simian virus 40 polyadenylation sites

In addition to the highly conserved AATAAA sequence, there is a requirement for specific sequences downstream of polyadenylic acid [poly(A)] cleavage sites to generate correct mRNA 3' termini. Previous experiments demonstrated that 35 nucleotides downstream of the E2A poly(A) site were sufficient but 20 nucleotides were not. The construction and assay of bidirectional deletion mutants in the adenovirus E2A poly(A) site indicates that there may be redundant multiple sequence elements that affect poly(A) site usage. Sequences between the poly(A) site and 31 nucleotides downstream were not essential for efficient cleavage. Further deletion downstream (3' to +31) abolished efficient cleavage in certain constructions but not all. Between +20 and +38 the sequence T(A/G)TTTTT was duplicated. Function was retained when one copy of the sequence was present, suggesting that this sequence represents an essential element. There may also be additional sequences distal to +43 that can function. To establish common features of poly(A) sites, we also analyzed the early simian virus 40 (SV40) poly(A) site for essential sequences. An SV40 poly(A) site deletion that retained 18 nucleotides downstream of the cleavage site was fully functional while one that retained 5 nucleotides downstream was not, thus defining sequences required for cleavage. Comparison of the SV40 sequences with those from E2A did not reveal significant homologies. Nevertheless, normal cleavage and polyadenylation could be restored at the early SV40 poly(A) site by the addition of downstream sequences from the adenovirus E2A poly(A) site to the SV40 +5 mutant. The same sequences that were required in the E2A site for efficient cleavage also restored activity to the SV40 poly(A) site.

Synthesis, tissue distribution and tumor uptake of 99mTc- and 67Ga-tetrasulfophthalocyanine

Complexes of tetrasulfophthalocyanine with 99mTc, 69Ga and 67Ga were prepared by the condensation of sulfophthalic acid with the appropriate metal-species. The Ga-complex was also obtained by exchange of the central hydrogens of the empty tetrasulfophthalocyanine. The labeled complexes were purified by thin layer chromatography and characterized by their chromatographic properties. Their biodistribution in rabbits and tumor-bearing rats revealed that most of the radioactivity accumulated in the kidneys, liver, ovaries, adrenals and spleen. Comparison of these distribution pattern with those of [99mTc]pertechnetate and 67Ga-citrate confirmed the in vivo stability of the labeled complexes. The 67Ga-complex reached better tumor-to-blood and tumor-to-muscle ratios than 67Ga-citrate.

The ability of thapsigargin and thapsigargicin to activate cells involved in the inflammatory response

The ability of thapsigargin and thapsigargicin to activate mast cells and leukocytes has been investigated. The thapsigargin-induced histamine release from rat peritoneal mast cells was found to be dependent on the concentration of thapsigargin, the purity of the mast cell preparations, and the number of mast cells in suspension. Thapsigargin induced histamine release from human basophil leukocytes. Thapsigargin induced beta-glucuronidase and lysozyme release from human neutrophil leukocytes. Thapsigargin caused a release of histamine from mesentery, lung, and heart mast cells of the rat, but only to a minor extent from the corresponding guinea-pig cells. Thapsigargicin induced histamine release from mesentery, lung, and heart mast cells of the rat at concentrations from 0.1 microM but provoked only a release from the corresponding guinea-pig cells in the concentration-range 0.16 to 1.6 microM. Thapsigargin increased the cytoplasmic free calcium level in intact human blood platelets at concentrations from 3.0 nM.

Isolation and properties of cardiac and other mast cells from the rat and guinea-pig

A method is described for the enzymic dispersion into their component cells of cardiac tissues from the rat and guinea-pig. The resulting suspensions contain ca. 1% free mast cells and exhibit a low spontaneous release of histamine. The reactivity of these cells towards a number of defined chemical histamine liberators is compared with that of other connective tissue mast cells from the same animals. The results obtained are discussed in terms of the general functional heterogeneity of mast cells from different locations.

Functional characteristics of mucosal and connective tissue mast cells of man, the rat and other animals

Mast cells from different species and even from given tissues within a particular animal are shown to differ in their responsivity to histamine liberators and anti-allergic drugs. The significance of these findings is discussed.

Studies on histamine secretion from enzymically dispersed cutaneous mast cells of the rat

A method has been developed for the enzymic dissociation of rat skin into its component cells. The resulting suspensions contained 3-5% mast cells. The latter were intact as judged by light microscopy and exhibited a low spontaneous release of histamine. Cells obtained from actively sensitized animals released histamine on challenge with specific antigen. The process was rapid, being essentially complete within 1 min, and was both calcium-and temperature-dependent. The cells also responded to antirat IgE and to calcium ionophores but showed a selective, time-dependent reactivity toward defined chemical histamine liberators. On the basis of these results the properties of the cutaneous mast cell are compared with those previously reported for mastocytes from other sources and discussed in terms of the general heterogeneity of this cell population.

Requirement of a downstream sequence for generation of a poly(A) addition site

The 3' terminus of most, if not all, eucaryotic polyadenylated mRNAs is formed as a result of endonucleolytic cleavage of a larger precursor RNA. That is, transcription does not terminate at the mRNA 3' sequence but rather proceeds through this site, terminating at some distance downstream. Using a plasmid containing the adenovirus E2A transcriptional unit, we have investigated the sequence requirement for the formation of a mature mRNA 3' terminus, focusing on the role of sequences immediately distal to the poly(A) addition site. Deletion mutants were constructed in the region distal to the poly(A) addition site and assayed by transfection into human 293 cells. The results demonstrate that 35 nucleotides distal to the site of poly(A) addition are sufficient for the formation of a mature E2 mRNA. However, removal of an additional 15 nucleotides, leaving 20 nucleotides distal to the poly(A) site, abolished the ability to produce functional E2A mRNA. The defect in the production of functional mRNA from such a mutant appears to be in the proper cleavage of the primary transcript at the poly(A) addition site. It would thus appear that sequences immediately distal to the site of poly(A) addition do not contribute to the mature mRNA but are essential for the formation of mature mRNA.

Rhizobium meliloti Tn5 induced auxotrophic mutants responding to different biosynthetic intermediates

Using a suicide plasmid as a vector, the kanamycin–neomycin resistance conferring transposon Tn5 was introduced into the genome of the two Rhizobium meliloti strains 444 and M28str. Among clones carrying random Tn5 insertions, about 0.3% auxotrophic mutants were isolated from each strain. Tn5 was found to integrate preferentially into genes involved in syntheses of adenine, arginine, leucine, pyrimidines, sulphur-containing amino acids, and tryptophan. Growth responses to biosynthetic intermediates uncovered four and two groups of methionine- and tryptophan-requiring mutants, respectively.

Psychiatric patients who discharge themselves against medical advice

Hospital treatment staff are constantly faced with the problem of psychiatric patients who discharge themselves against medical advice before their treatment is completed. A total of 50 patients who signed themselves out of the 9th floor service of the Clarke Institute of Psychiatry, over a two year period, were analyzed. When compared with a random sample of patients who remained for the duration of their treatment, the authors found the AMA patients to have the following characteristics: The patient is likely to be a young male, admitted as an emergency, remain in hospital for three days or less and have a diagnosis of personality disorder or schizophrenia. The authors conclude with a number of recommendations to assist in dealing with the problem.

Maxillary sinus hypoplasia and superior orbital fissure asymmetry

Misdiagnosis of maxillary sinus hypophasia usually as sinus infection, sometimes as neoplasm, can lead to unnecessary and difficult surgical explorations. Associated anatomical abnormalities, e.g., caudal displacement of the ipsilateral frontal lobe of the brain or central position in the maxilla of the infraorbital nerve may create unexpected surgical hazards. Associated orbital enlargement can lead to diagnostic confusion in the investigation of headache, especially if the superior orbital fissures show marked asymmetry suggesting erosion. Projection of the fissure into the antrum in Waters view can simulate trabeculation of the sinus or fracture of the inferior orbital rim. Radiologic examination of 500 patients without intracranial or intraorbital lesions revealed maxillary sinus hypoplasia in 36 cases (7.2%) and in half the hypoplasia was unilateral (sinus asymmetry); aplasia was not encountered. Fissure asymmetry was present in 30 cases (6%), being present in 3.66% of patients with normally developed sinuses and in 36.1% of the hypoplasia patients. The appearances and measurements of the fissure are presented and examples of marked normal fissure asymmetry are demonstrated. Maxillary sinus hypoplasia is classified in this series as grade I-mild hypoplasia with limited inferolateral expansion (4 cases) and grade II in which there is also a curved orbital floor and lateral displacement of the adjacent nasal wall (32 cases).

The pathways of ammonium assimilation in Rhizobium meliloti

Two pathways of ammonium assimilation are known in bacteria, one mediated by glutamate dehydrogenase, the other by glutamine synthetase and glutamate synthase. The activities of these three enzymes were measured in crude extracts from four Rhizobium meliloti wild-type strains, 2011, M15S, 444 and 12. All the strains had active glutamine synthetase and NADP-linked glutamate synthase. Assimilatory glutamate dehydrogenase activity was present in strains 2011, M15S, 444, but not in strain 12. Three glutamate synthase deficient mutants were isolated from strain 2011. They were unable to use 1 mM ammonium as a sole nitrogen source. However, increased ammonium concentration allowed these mutants to assimilate ammonium via glutamate dehydrogenase. It was found that the sole mode of ammonium assimilation in strain 12 is the glutamine synthetase-glutamate synthase route; whereas the two pathways are functional in strain 2011.

Quantification of digoxin by enzyme immunoassay: synthesis of a maleimide derivative of digoxigenin succinate for enzyme coupling

We synthesized the m-maleimidobenzoyl derivative of digoxigenin-3-0-succinate (through a p-phenylenediamine bridge) as a hapten derivative directed towards coupling to sulfhydryl grouos of beta-galactosidase. Prepared enzyme conjugate had about 97% of the enzyme labeled with the hapten derivative while retaining full enzyme activity. The enzyme immunoassay for digoxin we prepared showed a maximum sensitivity of 30 pg per assay (c.v. = 3%) with minimal cross-reaction with digotoxin (3.8%). Our method for hapten conjugation to beta-galactosidase is highly efficient and is simple and easily replicated.

Nicotine antibodies: comparison of ligand specificities of antibodies produced against two nicotine conjugates

Conjugates between bovine serum albumin and (R,S)-2-aminonicotine were produced, and these conjugates were employed in rabbits and goats for the production of nicotine antibodies. In the assay of nicotine, an 125I-tyrosine methyl ester derivative of (R,S)-6-aminonicotine was employed as radioligand. The antibody-bound derivative was separated from the free derivative by charcoal adsorption (0.5% charcoal, 0.1% dextran T-70, 0.1% bovine serum albumin pH 7.3). Among the twenty five nicotine derivatives and metabolites examined, (R,S)-6-aminonicotine gave the highest cross-reaction. Cross-reaction with cotinine, a major mammalian metabolite of nicotine, was less than 0.1% for both the rabbit-derived and goat-derived antisera. Cross-reaction by other metabolites, such as (S)-nicotine-N'-oxide, (S)-nornicotine, and N-methylpyrrolidine was less than 1%. The antibodies produced were thus highly specific to nicotine. The radioimmunoassay for nicotine showed a maximum sensitivity of 10 ng/ml in 50-microliter plasma samples for both antisera. After the smoking of a single cigarette (1.2 mg nicotine content in mainstream) the peak of blood plasma level of nicotine in the subjects varied from 20--104 ng/ml, and high levels of nicotine were not necessarily found in heavy smokers.

Practical enzyme immunoassay for plasma cortisol using beta-galactosidase as enzyme label

Enzyme immunoassay for cortisol was developed using beta-galactosidase as an enzyme label and m-maleimidobenzoyl derivatives of cortisol, i.e. cortisol-21-m-maleimidobenzoate (CT-MB) and cortisol-21-hemisuccinate conjugated with m-maleimidobenzoic acid through p-phenylenediamine linkage (CHS-MB), as the haptens coupled to sulfhydryl groups of the enzyme. This enzyme-coupling procedure was highly efficient; over 90% of the enzyme was labeled while full enzyme activity was retained. CHS-MB-beta-galactosidase conjugate showed high immunoreactivity to antibody produced against cortisol-21-hemisuccinate-bovine serum albumin but showed poor displacement with the added cortisol. CT-MB-beta-galactosidase conjugate, however, showed not only a high immunoreactivity to the antibody but also displaced well with cortisol, showing maximum sensitivity of 1 microgram/dl with a 20-microliter sample size. Modification around the linkage of cortisol derivative resulted in high sensitivity to cortisol. Cross-reactions to cortisol-21-acetate, cortisone, and corticosterone were 150%, 10%, and 7%, respectively. The accuracy, precision and correlation with RIA of this method were satisfactory for clinical application.