Denileukin diftitox

Primary cutaneous T-cell lymphomas (CTCLs) encompass a wide variety of lymphomas that are characterized by the localization of the malignant lymphocytes to the skin at presentation. They are slow-growing and rare, occurring in fewer than 1,000 people annually. Patients may go for months to years with skin abnormalities before being diagnosed. Mycosis fungoides and Sezary syndrome are the most common forms of CTCL and are considered to be indolent diseases. Patients with T1 disease have a normal life expectancy, whereas patients who undergo transformation to large cell lymphoma (8%-23% of patients) have a poor prognosis, with mean survival ranging from 2-19 months.

The hypervariable domain of the murine leukemia virus surface protein tolerates large insertions and deletions, enabling development of a retroviral particle display system

The surface proteins (SU) of murine type-C retroviruses have a central hypervariable domain devoid of cysteine and rich in proline. This 41-amino-acid region of Friend ecotropic murine leukemia virus SU was shown to be highly tolerant of insertions and deletions. Viruses in which either the N-terminal 30 amino acids or the C-terminal 22 amino acids of this region were replaced by the 7-amino-acid sequence ASAVAGA were fully infectious. Insertions of this 7-amino-acid sequence at the N terminus, center, and the C terminus of the hypervariable domain had little effect on envelope protein (Env) function, while this insertion at a position 10 amino acids following the N terminus partially destabilized the association between the SU and transmembrane subunits of Env. Large, complex domains (either a 252-amino-acid single-chain antibody binding domain [scFv] or a 96-amino-acid V1/V2 domain of HIV-1 SU containing eight N-linked glycosylation sites and two disulfides) did not interfere with Env function when inserted in the center or C-terminal portions of the hypervariable domain. The scFv domain inserted into the C-terminal region of the hypervariable domain was shown to mediate binding of antigen to viral particles, demonstrating that it folded into the active conformation and was displayed on the surface of the virion. Both positive and negative enrichment of virions expressing the V1/V2 sequence were achieved by using a monoclonal antibody specific for a conformational epitope presented by the inserted sequence. These results indicated that the hypervariable domain of Friend ecotropic SU does not contain any specific sequence or structure that is essential for Env function and demonstrated that insertions into this domain can be used to extend particle display methodologies to complex protein domains that require expression in eukaryotic cells for glycosylation and proper folding.

Adaptations of myocardial beta-adrenergic receptor complex in hibernating marmots

Properties of marmot (Marmota flaviventris) myocardial beta-adrenergic receptor complex (beta-AR) were evaluated during hibernation (H), in summer (S) animals, and in animals aroused from hibernation (C). The results obtained for S and C animals were identical, and only the results for C animals are shown. In H-animal myocardial membrane preparations assayed at 37 degrees C, isoproterenol-dependent adenylate cyclase activity (ACA) was consistently higher, whereas the synergistic contribution of 5'-guanylylimidodiphosphate [Gpp(NH)p] in this reaction was reduced. When assayed at 10 degrees C, only the ACA in H animals responded to the combination of isoproterenol and Gpp(NH)p. In contrast, at 10 degrees C, ACA in response to Gpp(NH)p alone is essentially equal in H and C animals. Hibernation did not change myocardial beta-AR receptor density or affinity. In contrast, analysis of isoproterenol displacement of [125I]iodocyanopindolol revealed that the proportion of beta-AR in the high-affinity state was substantially greater in H than in C animals, and this relationship was retained even in the presence of Gpp-(NH)p. In an evaluation of the role of the GTP binding proteins that couple the beta-AR to the effector adenyl cyclase, we determined that there was no change in the cholera toxin- or pertussis toxin-dependent ADP ribosylation patterns. Immunochemical detection of the individual GTP binding proteins revealed no change in the levels of G alpha i1, G alpha i2, or G alpha i3. In contrast, we observed a hibernation-associated decrease in G alpha o associated with the plasma membrane-enriched particulate fraction. (ABSTRACT TRUNCATED AT 250 WORDS)

Modification of antisense phosphodiester oligodeoxynucleotides by a 5' cholesteryl moiety increases cellular association and improves efficacy

Phosphodiester oligodeoxynucleotides bearing a 5' cholesteryl (chol) modification bind to low density lipoprotein (LDL), apparently by partitioning the chol-modified oligonucleotides into the lipid layer. Both HL60 cells and primary mouse spleen T and B cells incubated with fluorescently labeled chol-modified oligonucleotide showed substantially increased cellular association by flow cytometry and increased internalization by confocal microscopy compared to an identical molecule not bearing the chol group. Cellular internalization of chol-modified oligonucleotide occurred at least partially through the LDL receptor; it was increased in mouse spleen cells by cell culture in lipoprotein-deficient medium and/or lovastatin, and it was decreased by culture in high serum medium. To determine whether chol-modified oligonucleotides are more potent antisense agents, we titered antisense unmodified phosphodiester and chol-modified oligonucleotides targeted against a mouse immunosuppressive protein. Murine spleen cells cultured with 20 microM phosphodiester antisense oligonucleotides had a 2-fold increase in RNA synthesis, indicating the expected lymphocyte activation. Antisense chol-modified oligonucleotides showed an 8-fold increase in relative potency: they caused a 2-fold increase in RNA synthesis at just 2.5 microM. The increased efficacy was blocked by heparin and was further increased by cell culture in 1% (vs. 10%) fetal bovine serum, suggesting that the effect may, at least in part, be mediated via the LDL receptor. Antisense chol-modified oligonucleotides are sequence specific and have increased potency as compared to unmodified oligonucleotides.

Trypanosoma cruzi: mechanisms of intracellular calcium homeostasis

Regulation of intracellular Ca2+ homeostasis was characterized in epimastigote forms of Trypanosoma cruzi using the fluorescence probe Fura-2. Despite an increase in extracellular Ca2+, [Ca2+]o, from 0 to 2 mM, cytosolic Ca2+, [Ca2+]i, increased only from 85 +/- 9 to 185 +/- 21 nM, indicating the presence of highly efficient mechanisms for maintaining [Ca2+]i. Exposure to monovalent Na+ (monensin)-, K+ (valinomycin, nigericin)-, and divalent Ca2+ (ionomycin)-specific ionophores, uncouplers of mitochondrial respiration (oligomycin), inhibitors of Na+/K(+)-ATPase (ouabain), and Ca(2+)-sensitive ATPase (orthovanadate) in 0 or 1 mM [Ca2+]o resulted in perturbations of [Ca2+]i, the patterns of which suggested both sequestration and extrusion mechanisms. Following equilibration in 1 mM [Ca2+]o, incubation with orthovanadate markedly increased [Ca2+]i, results which are compatible with an active uptake of [Ca2+]i by endoplasmic reticulum. In contrast, equilibration in 0 or 1 mM [Ca2+]o did not influence the relatively smaller increase in [Ca2+]i following incubation with oligomycin, suggesting a minor role for the mitochondrial compartment. In cells previously equilibrated in 1 mM [Ca2+]o, exposure to monensin or ouabain, conditions known to decrease the [Na+]o/[Na+]i gradient, upon which the Na+/Ca2+ exchange pathways are dependent, markedly increased [Ca2+]i. In a complementary manner, decreasing the extracellular Na+ gradient with Li+ increased [Ca2+]i in a dose-dependent manner. Finally, the calcium channel blockers verapamil and isradipine inhibited the uptake of Ca2+ by greater than 50%, whereas diltiazem, nifedipine, and nicardipine were ineffective. The results suggest that epimastigote forms of T. cruzi maintain [Ca2+]i by uptake, sequestration, and extrusion mechanisms, with properties common to eukaryotic organisms.

Stimulation of calcium influx in HL60 cells by cholesteryl-modified homopolymer oligodeoxynucleotides

Cholesteryl-modified 15-mer homopolymers of cytidine and thymidine phosphodiester oligodeoxynucleotides (chol-OdC15 and chol-OdT15), but not chol-modified heteropolymeric oligos or chol-modified phosphorothioate oligos, were found to increase cytosolic free Ca2+ in HL60 cells. A flow cytometer and the calcium-sensitive dye indo-1 were used to make multiparameter measurements on the HL60 cells. Chol-OdC15 (5-10 microM) triggered a rapid increase (within 1 min) in [Ca2+]i, with a subsequent slow decline to baseline over 15 min in the continuous presence of agonist. The effect was preserved after unloading the intracellular Ca2+ stores with caffeine and ryanodine. The effect was not sensitive to membrane depolarization by KCl (60 mM) or nimodipine, a dihydropyridine calcium channel antagonist. An increase in [Ca2+]i was absent in a Ca(2+)-free solution and was inhibited by the inorganic Ca2+ channel blocker Cd2+. The results suggest that Ca2+ influx activated by the chol-oligomer is probably mediated by receptor-operated Ca2+ channels. This effect may be due to direct binding of the chol-oligo to the channel or to induced conformational changes due to modification of the local microenvironment.

Two subtypes of dihydropyridine-sensitive calcium channels in rat ventricular muscle

Two opposite inotropic effects of the dihydropyridine activators, CGP 28392 and Bay K 8644, given at the same concentration (1-2 microM) were found in rat papillary muscles: a positive effect in polarized tissue (4 mM KCl) and a negative one during partial depolarization. The depressive effect found at a low rate or after a short rest was associated with marked prolongation of the Ca2(+)-mediated action potential, indicating that the drugs behave as Ca channel stimulators. The depressive effect of the activation on the resting state contraction was antagonized by nifedipine (2 microM) and high Mg2+ (5 mM). It was suggested that at least two subtypes of the L-type, dihydropyridine-sensitive channels underlie the opposite inotropic responses of the activators. The positive effect is apparently caused by conventional stimulation of Ca2+ entry through the cell membrane, whereas the negative effect is probably due to the stimulation of Ca2+ efflux from the sarcoplasmic reticulum, leading to depletion of intracellular stores. The effect was proposed to be mediated by activation of junctional channels linked to sarcoplasmic reticulum Ca2+ release. An important role for these channels in triggering the sarcoplasmic reticulum Ca2+ release and regulation of force-frequency relation is proposed.

Ca2+-antagonistic properties of phospholipase A2 inhibitors, mepacrine and chloroquine

The effects of putative phospholipase A2 inhibitors mepacrine and chloroquine on membrane ionic currents were studied in intact frog atrial trabeculae. Both agents decreased slow calcium channel current Isi and fast sodium channel current If. Isi was affected twice at least in comparison to If. Half-block of Isi was observed at approximately 10(-6) mol/l mepacrine and at approximately 10(-5) mol/l chloroquine. These effects on transmembrane ionic transport should be considered when using the above agents as phospholipase inhibitors or antiarrhythmic drugs.

Paradoxical reversion of the inhibitory effects of dihydropyridine enantiomers on the calcium current in frog heart by CGP 28861

A dihydropyridine CGP 28861 (5 x 10(-6) M) did not change slow inward Ca current as measured by the double sucrose gap method in frog atrial fibres but decreased the agonist effects of Bay K 8644, CGP 28392, (+)-(S)-202-791 and the antagonist effects of nifedipine and (+)-(PN)-200-110. Paradoxically, the weak antagonists (-)-(R)-202-791, (-)-(PN)-200-110 and (+)-Bay K 8644 increased Ca-current after washout of CGP 28861. These data suggest that CGP 28861 can convert the dihydropyridine Ca-channel receptor from an antagonistic site into an agonistic one.

Ryanodine as a trigger of tension oscillations in rat ventricular muscle

In rat ventricular muscles, ryanodine (10-30 nM) evoked tension oscillation in the relaxation phase of an isometric twitch (relaxation oscillations) and an increase of tonic tension (ryanodine contracture). Both events were more pronounced in Ca2+-loaded rat muscles due to the addition of 0.5 microM adrenaline, an increase in the Ca2+ concentration in the solution and high muscle activity. The ryanodine-induced tension oscillations were comparable to those triggered by caffeine in this species. In both cases, blockers of the release of Ca2+ from the sarcoplasmic reticulum, namely tetracaine and dantrolene, abolished the relaxation oscillations and the ryanodine contracture. The results suggest that the ability of low concentrations of ryanodine to facilitate the release of Ca2+ from the sarcoplasmic reticulum, as shown recently in biochemical experiments, makes a direct contribution to triggering the relaxation oscillations and the ryanodine contracture in intact ventricular muscles. The Ca2+ load of the sarcoplasmic reticulum appears to be essential for the manifestation of the ryanodine Ca2+-releasing activity in rat ventricular muscles.

Biphasic inotropic effects of a Ca2+ channel activator CGP28392 in rat myocardium: possible relation to intracellular Ca2+ release

1. The inotropic effect of a Ca2+-entry stimulator, CGP28392, (CGP) was compared in rat and frog myocardium in a concentration- and time-dependent manner. 2. Frog preparations exhibited a persistent positive inotropic effect following prolonged treatment with CGP. 3. Compared to amphibian myocardium, rat ventricular muscle exhibited a biphasic time-dependent response to CGP: an initial increase in the twitch tension amplitude of 30% was changed to a reduction of 80% below the control level during prolonged exposure to CGP (stimulation frequency, 0.2 Hz). 4. Following prolonged incubation with CGP, the resting-state contraction was decreased and the negative force-frequency relation was converted into a positive one in rat muscle. 5. Since sarcoplasmic reticulum (SR) is the major source of Ca2+ in a rested-state contraction, inhibition by CGP suggests an additional, intracellular action of the Ca2+ channel activator on SR-Ca2+ release in rat myocardium.

Two types of spontaneous contractions in rat myocardium and their possible relation to different Ca release processes

The potency of putative blockers (lidocaine, dantrolene Na, DAN, SKF 525A) for various forms of Ca2+ release from sarcoplasmic reticulum (SR) against two types of spontaneous contractions induced by 0.5 mM caffeine (caffeine response) or myocardium Ca2+ overload (after-contractions) was tested in rat papillary muscle. There were differences in the sensitivity of spontaneous contractions to the agents employed. The caffeine response was depressed by DAN but not affected by lidocaine. Conversely, conventional diastolic after-contractions were eliminated by lidocaine and SKF 525A but DAN failed to affect them. The two types of spontaneous contractions were suggested to be triggered by different CA2+ release processes supposedly originating from different SR compartments.

Atypical Brown-Sequard syndrome following gunshot wound to the face

A case report of an atypical Brown-Sequard syndrome following a gunshot wound to the face has been described. Initial physical examination gave no evidence of spinal cord injury. Later examination revealed neurologic deficits consistent with a Brown-Sequard syndrome. This article shows the possibly delay in onset of clinical manifestations of cord injuries that may occur following head and neck trauma and the importance of a thorough physical, neurologic, and radiographic examination of the traumatized patient.