Influence of α-interferon therapy on blood lymphoid cells

Summary The influence of natural -interferon (-IFN) therapy (3×10⁶ units i.m. daily) on blood lymphoid cells was studied in 20 patients with gynecological neoplasias (7 patients with condylomata accuminata and 13 patients with ovarian carcinoma). There was a statistically significant increase in the intracellular levels of 2'–5'oligoadenylate synthese 1 day after the first injection of IFN and with few exceptions this activity remained increased during 3 months of treatment. In most of the patients, the capacity of blood lymphoid cells to produce IgA, IgG, and IgM following stimulation with pokeweed mitogen was decreased 1 day after the first injection of IFN and with few exceptions it remained low during 6 months of IFN therapy. In most patients there was a decrease in the capacity of lymphoid cells to act as stimulator or responder cells in a mixed lymphocyte culture during IFN therapy. The -IFN therapy had no major influence on the response of lymphoid cells to mitogens. We conclude, that neither this nor our previous studies on the influence of IFN therapy on immunological functions have given support to the hypothesis that the antitumor action of IFN is mediated by the immune system.     

Modulation of phosphoinositide metabolism in rat brain slices by excitatory amino acids,arachidonic acid,and GABA

In rat brain slices the synthesis of [³H]phosphoinositides and the production of [³H]inositol monophosphate (IP₁) induced by norepinephrine (NE) were inhibited by glutamate. Calcium concentrations were varied to test if these inhibitory effects of glutamate were mediated by a calcium-dependent process. Although reducing calcium or addition of the calcium antagonist verpamil reduced the inhibitory effects of glutamate, these results were equivocal because reduced calcium directly decreased agonist-induced [³H]phosphoinositide synthesis. The inhibitory effects of glutamate were mimicked by quisqualate in a dose-dependent manner, but none of a variety of excitatory amino acid receptor antagonists modified the inhibition caused by quisqualate. It is suggested that glutamate activates a quisqualate-sensitive receptor (for which an antagonist is not available) and causes inhibition of phosphoinositide hydrolysis mediated in part by a direct or indirect inhibitory effect of calcium on phosphoinositide synthesis. Modulatory effects of arachidonic acid were examined because glutamate and calcium can activate phospholipase A₂. Arachidonic acid caused a rapid and dose-dependent inhibition of [³H]phosphoinositide synthesis and of NE-stimulated [³H]IP₁ production. A similar inhibition of the response to carbachol also occurred. The inhibition caused by arachidonic acid was unchanged by addition of inhibitors of cyclooxygenase or lipoxygenase. Activation of phospholipase A₂ with melittin caused inhibitory effects similar to those of arachidonic acid. Inhibitors of phospholipase A₂ were found to impair phosphoinositide metabolism, likely due to their lack of specificity for phospholipase A₂. Further studies were carried out in slices that were prelabelled with [³H]inositol in an attempt to separate modulatory effects on [³H]phosphoinositide synthesis and agonist-stimulated [³H]IP₁ production. Several excitatory amino acid agonists inhibited NE-stimulated [³H]IP₁ production. This inhibitory inter-action could be due to impaired synthesis of [³H]phosphoinositides because, even though the slices were prelabeled, addition of unlabelled inositol reduced NE-stimulated [³H]IP₁ production, indicating that continuous regeneration of [³H]phosphoinositides is required. In contrast to the inhibitory effects of the excitatory amino acids, gamma-aminobutyric acid (GABA) enhanced the response to NE in cortical and hippocampal slices. GABA also enhanced the response to carbachol in hippocampal and striatal slices and to ibotenic acid in hippocampal slices. Baclofen potentiated the response to NE similarly to the effect of GABA and baclofen partially blocked the inhibitory effect of arachidonic acid but did not alter that of quisqualate.Abbreviations AMPA -amino-3-hydroxy-5-methyl-4-isoxazolepropionic - acid AP₄ dl-2-amino-4-phosphonobutyric acid - BPB bromphenacyl bromide - BSA bovine serum albumin - CNQX 6-cyano-7-nitroquinoxaline-2,3-dione - DFMO -difluoromethylornithine - DIDS diisothiocyanotostilbene-2,2-disulfonic acid - EGTA ethyleneglycol-bis-N - N, N N-tetraacetic acid - GABA -aminobutyric acid - GDEE glutamate diethyl ether - -GG -glutamylglycine - IP₁ inositol monophosphate - IP₂ inositol bisphosphate - IP₃ inositol trisphosphate - NDGA nordihydroguaiaretic acid - NE norepinephrine - NMDA N-methyl-d-aspartate     

Interaction of alpha-N-Acetyl-beta-endorphin and calmodulin

Acetylation at the -amino terminal is a common post-translational modification of many peptides and proteins. In the case of the potent opiate peptide -endorphin, -N-acetylation is a known physiological modification that abolishes opiate activity. Since there are no known receptors for -N-acetyl--endorphin, we have studied the association of this peptide with calmodulin, a calcium-dependent protein that binds a variety of peptides, phenothiazines, and enzymes, as a model system for studying acetylated endorphin-protein interactions. Association of the acetylated peptide with calmodulin was demonstrated by cross-linking with bis(sulfosuccinimidyl)suberate; like -endorphin, adducts containing 1 mol and 2 mol of acetylated peptide per mole calmodulin were formed. Some of the bound peptides are evidently in relatively close proximity to each other since, in the presence of amidated (i.e., lysine-blocked) calmodulin, cross-linking yielded peptide dimers. The acetylated peptide exhibited no appreciable helicity in aqueous solution, but in trifluoroethanol (TFE) considerable helicity was formed. Also, a mixture of acetylated peptide and calmodulin was characterized by a circular dichroic spectrum indicative of induced helicity. Empirical prediction rules, applied earlier to -endorphin, suggest that residues 14–24 exhibit -helix potential. This segment has the potential of forming an amphipathic helix; this structural unit is believed to be important in calmodulin binding. The acetylated peptide was capable of inhibiting the calmodulin-mediated stimulation of cyclic nucleotide phosphodiesterase (EC 3.1.4.17) activity with an effective dose for 50% inhibition of about 3 µM; this inhibitory effect was demonstrated using both an enzyme-enriched preparation as well as highly purified enzyme. Thus, acetylation at the -amino terminal of -endorphin, although abolishing opiate activity, does not interfere with the binding to calmodulin. Indeed, -endorphin and the -N-acetylated peptide behave very similarly with respect to calmodulin association.Portions of this work are in partial fulfillment of the requirements for the Ph.D. degree from Vanderbilt University.     

Biosynthesis of Territrems by Aspergillus terreus

Different radioactive precursors were added to 8-day potato-dextrose liquid cultures of Aspergillus terreus 23-1. Territrems were isolated from chloroform extracts of the cultures at day 14 and purified by thin-layer chromatography and high-pressure liquid chromatography. The territrem B obtained was treated with alkaline hydrogen peroxide, and 3, 4, 5-trimethoxy benzoic acid was isolated from an ethyl acetate extract of the reaction mixture and purified by thin-layer chromatography and high-pressure liquid chromatography. By comparison of the specific radioactivities of territrem B and its cleaved aromatic product (disintegrations per minute per micromole of compound), it was demonstrated that the radioactivity of territrem B was located mainly on its aromatic moiety when [U-C]shikimate, l-[methyl-C]methionine, and l-[methyl-H]methionine were precursors; however, the radioactivity of territrem B was located mainly on its nonaromatic moiety when [2-C]mevalonate was the precursor. Mevinolin, a specific inhibitor of beta-hydroxyl beta-methyl glutaryl coenzyme A reductase, was shown to inhibit production of territrems by A. terreus 23-1. When [U-C]acetate was used as a precursor, mevinolin inhibited the incorporation of radioactive carbon into territrem but mevinolin did not inhibit incorporation of radioactive carbon from [2-C]mevalonate into territrem.     

An electronic mechanism in the action of drugs, ATP, transmitters and other cardinal adsorbents. II. Effect of ouabain on the relative affinities for Li+, Na+, K+, and Rb+ of surface anionic sites that mediate the entry of Cs+ into frog ovarian eggs

Ouabain enhanced the inhibitory effects of Li+, Na+, and K+ on the rate of Cs+ permeation into frog ovarian eggs while it reduced the inhibiting effect of Rb+. The data agree with earlier demonstrated effects of ouabain on the rank order of selective accumulation of the five alkali-metals in frog muscles and on the relative effectiveness of glycine, Li+, Na+, K+, Rb+, and Cs+ in inhibiting the rate of entry of Cs+ into frog sartorius muscle. In all three cases, the ouabain behaved as an electron-donating cardinal adsorbent (EDC) causing a rise of the electron density (c-value) of the beta- and gamma-carboxyl groups in the cell cytoplasm (for selective accumulation) and on the cell surface (for selective ion permeation). Explanations based on the association-induction hypothesis were offered why an EDC like ouabain does not initiate cell activation (like veratridine does) and why Ca++ and tetradotoxin delays or inhibits physiological and artificial cell activation.     

新生儿巨细胞病毒感染的检测

建立了用ELISA检测巨细胞病毒(HCMV)IgA抗体的方法,並用于检测北京地区100对母婴的HCMV抗体,母血、脐带血、母乳中HCMV-IgG抗体的阳性率分别为83％,75％和38％,HCMV-IgA抗体的阳性率分别为19％,15％和58％,对其中的16名婴儿半年后追踪观察,5名出生时母、脐血全为阴性的,有2名抗体阳转。8名出生时母、脐血均阳性的,有1名IgA仍阳性並检查发现肝大肋下二指。另1名IgG持续阳性,其他6名婴儿抗体转阴。3名出生时母血HCMV-IgG阳性者中,1名婴儿IgA和‘gG转阳,此时母亲IgA也阳转。随访的16名婴儿中有3名可能是生后半年内受HCMV感染。     

银额果蝇的B染色体研究 2.昆明群体的生活力和B染色体的关系

本文分析了钮额果蝇的生活力和B染色体的关系。结果表明,银额果蝇的B染色体在其生长和发育过程中具双重性调节作用。一方面,B染色体以单一的形式存在于单雌系核型中,即1B或2Bs,可刺激生长、发育,增强生活力。另一方面,在单雌系的细胞中存在多条B染色体,并形成核型多态性,这似乎对生长和发育又有一定的抑制作用而减弱其生活力。     

Sensitization of low-dose-rate irradiation by nonlethal hyperthermia

To assess whether hyperthermia could radiosensitize cells irradiated at a low dose rate, Chinese hamster V79 cells were simultaneously heated and irradiated at 0.86 Gy/h. The data showed that heat treatments at 39 and 40 degrees C, which did not induce heat killing alone or high-dose-rate radiosensitization, resulted in enhanced cell killing with low-dose-rate irradiation. The dose-modification factor (ratio of the slopes of the curves for low dose rate and high dose rate) was reduced to 1.8 at 39 degrees C and 1.4 at 40 degrees C, compared to a value of 2.1 at 37 degrees C. These data indicate that nonlethal heat treatments can cause enhanced radiosensitization under low-dose-rate conditions. The implications of these results for interstitial thermoradiotherapy are discussed.