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Relative proximity of domains in plasma membrane and smooth endoplasmic reticulum from rat liver.
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Enzyme recovery by continuous crosscurrent extraction.
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Cell-mediated immunity in patients with amebic abscess of the liver.
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Procainamide-induced antibodies to nucleoprotein, denatured and native DNA in human subjects.
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The effect of prostaglandin F2alpha on the counter-current transfer of 85krypton in the ovarian pedicle of the sheep.
A miniature Geiger-Müller probe was inserted into the corpus luteum in five anesthetized ewes. A similar probe was inserted into either the lumen of the adjacent fallopian tube or the opposite ovary. Overall, 17 infusions of 85Krypton-saline into the uterine vein were carried out in the five subjects. After each two minute infusion into the uterine vein, an increase in radioactivity was registered in the adjacent corpus luteum within 30 - 60 seconds. Maximum radioactivity was registered 1 - 3 minutes after the start of the infusion and within 10 minutes radioactivity had dropped to background [corrected] levels. In two out of three sheep a similar kpattern of 85Krypton transfer was registered in the adjacent fallopian tube. Only a negligible amount of radioactivity above background level was registered in the contralateral control ovary, a result in keeping with the known rapid clearance of 85Krypton from the circulation. There was no indication of any change in pattern of the counter current transfer of 85Krypton during the infusion of PGF2alpha (10 microng/hr) into the ovarian pedicle. These results suggest that the previously observed slow transfer of PGF2alpha itself in the ovarian pedicle may be due to physical rather than pharmacological properties of this prostaglandin.
Countercurrent chromatography.
Countercurrent chromatography is a newly developed versatile partition chromatography which totally eliminates the use of solid supports. The method utilizes the intriguing hydrodynamic behavior of two immiscible solvents in a rotating coiled tube. Various types of seal-free flow-through centrifuge schemes are introduced to facilitate a continuous elution process. The method yields high partition efficiencies comparable to liquid chromatography but without the complications arising from the use of solid supports. Countercurrent chromatography covers a wide spectrum of applicable samples ranging from small ions and molecules to macromolecules and even cell particles in both analytical and preparative scales.
Cell-surface changes induced by ectopic expression of the murine homeobox gene Hox-3.3.
Murine homeobox-containing genes (Hox genes) are postulated as playing key roles in the establishment of the anterior-posterior embryonic body axis, possibly providing cells with positional cues. Little is known, however, concerning how cells might respond to homeobox gene expression to interpret these cues. Since changes in the cell-surface are central to many processes in early development we reasoned that cells expressing different complements of Hox genes might have different surface properties. In order to investigate this we have used the sensitive, non-disruptive technique of multiple two-phase aqueous partition, which is able to detect small differences on the surface of intact cells. Using this technique we have found that ectopic expression of the murine Hox-3.3 gene in cultured cells induces reproducible changes in the cell surface. Changes only occurred above a threshold level of gene expression, but above this level a correlation between surface change and gene expression was seen. The implications for the establishment of a 'Hox' code of homeobox genes acting to specifically change cell-surface properties are discussed.
The role of enzymatic processing in the biological actions of substance P.
There is considerable evidence that substance P (SP) is a neurotransmitter in the CNS. Current findings suggest that the effects of synaptically released SP are terminated by enzymatic breakdown, primarily by endopeptidase 3.4.24.11 (endo 24.11). The products of cleavage by endo 24.11 include the amino-terminal fragment SP(1-7). Evidence suggests that SP is involved in mediating baroreceptor reflex activity in the nucleus of the solitary tract (NTS). Microinjection of SP into the NTS lowered blood pressure and heart rate. Microinjection of SP(1-7) into the NTS reproduced the effects of SP on both heart rate and blood pressure. Intra-NTS injection of phosphoramidon, an inhibitor of endo 24.11 activity, completely blocked the effects of a subsequent injection of SP. This blocking effect of phosphoramidon was unaltered by pretreatment with the opiate inhibitor naloxone. In contrast, phosphoramidon failed to block the depressor and bradycardic effects of SP(1-7). The implications of these findings regarding the role of endo 24.11 in the metabolism of SP are discussed.
A critical evaluation of plasma membrane fractionation.
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The synthesis of D-tryptophanyl-D-arginyl-D-phenylalanyl-D-histidyl-D-glutamic acid and its effect on melanotropic activity.
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Effects of DEAE-dextran on the partition of red blood cells in aqueous dextran-polyethylene glycol two-phase systems.
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Factors in the partition of red blood cells in aqueous dextran-polyethylene glycol two-phase systems.
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Blood clam (Anadara inflata) red cells. Partition in aqueous two-polymer phase systems.
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Blood clam (Anadara inflata) hemoglobins. Partition in aqueous two-polymer phase systems and alkali denaturation.
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A specific adenine nucleotide effect on the rat liver glucocorticoid receptor, demonstrated by aqueous two-phase partitioning.
The effect of mononucleotides on the cytosolic rat liver glucocorticoid receptor has been studied by the use of aqueous dextran-poly(ethylene glycol) two-phase partitioning. During incubations in 0.4 M KCl at 0 degrees C, millimolar concentrations of ADP and ATP, but not AMP, CTP, UTP and GTP, inhibit the increase in the receptor partition coefficient associated with receptor activation. This inhibition is counteracted by millimolar concentrations of theophylline and MgCl2. Two nonhydrolyzable analogues of ATP, alpha, beta-Methyleneadenosine 5'-triphosphate and beta, gamma-methyleneadenosine 5'-triphosphate, also inhibit the increase in the partition coefficient. alpha, beta-Methyleneadenosine 5'-triphosphate is much more potent than ATP in doing so, and this compound was also shown to reduce the amount of receptor to bind to DNA-Sepharose after the incubations. Thus, adenine nucleotides induce a change in the state of the receptor, apparently consisting in an inhibition of receptor activation.
Camptothecin and taxol: from discovery to clinic.
Camptothecin (CPT) and taxol are secondary metabolites found in the stembark of Camptotheca acuminata, a native of China, and Taxus brevifolia, found in the northwest Pacific coastal region of the USA, respectively. The compounds were isolated through bioassay-guided fractionation of various extracts and through chromatographic fractions. Their unique and hitherto unknown structures were elucidated by nuclear magnetic resonance, mass spectrometry and X-ray analysis. Both compounds have unique mechanisms of antitumor activity; CPT uniquely inhibits an enzyme, topoisomerase I, involved in DNA replication, while taxol binds to a protein, tubulin, thus inhibiting cell division. Taxol has been called the best new anticancer agent developed from natural products, showing particular efficacy against ovarian cancer. CPT and analogs singly or combined with cisplatinum show efficacy against solid tumors, breast, lung, and colorectal, which hitherto have been unaffected by most cancer chemotherapeutic agents.