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.     

Sorbitol Gum in Xerostomics: The Effects on Dental Plaque pH and Salivary Flow Rates1

Adequate salivary flow is important for patient comfort and maintenance of oral health. Xerostomia, or dry mouth, is a common clinical complaint. Masticatory and gustatory activity can stimulate salivary flow from functional salivary tissue and the use of sugarless mints and gums have been recommended to individuals who complain of xerostomia, but there are minimum clinical data. A clinical study assessing the effect on salivary flow rates and dental plaque pH of a sorbitol-sweetened chewing gum in subjects with the complaint of xerostomia was conducted. The chewing of the gum in this present study stimulated salivary flow in the subjects with xerostomia. Statistically significant stimulated whole mouth and parotid salivary flow rate increases were found when compared to unstimulated whole mouth and parotid salivary flow rates. Chewing of the sorbitol-sweetened gum also effectively reduced the drop in pH seen following the exposure to a fermentable carbohydrate. The findings of this present study indicate that chewing of a sorbitol-sweetened gum may be of benefit to patients with the complaint of xerostomia.     

Apparent decline in the harbour seal Phoca vitulina population near Hvaler, Norway, following an epizootic

From 1986-90 we tagged 98 harbour seal pups at Hvaler, Norway Fifteen were recovered later the same year of which 10 were recovered in 1988, when the seal population was infected by a morbillivirus The epizootic in 1988 resulted in a population decline of c 75% Predicted birth weight did not vary significantly before and after the epizootic Newborn harbour seals have antibodies against the morbillivirus two years after the outbreak of the disease     

The pH profile for acid-induced elongation of coleoptile and epicotyl sections is consistent with the acid-growth theory

The acid-growth theory predicts that a solution with a pH identical to that of the apoplast of auxintreated tissues (4.5–5.0) should induce elongation at a rate comparable to that of auxin. Different pH profiles for elongation have been obtained, however, depending on the type of pretreatment between harvest of the sections and the start of the pH-incubations. To determine the acid sensitivity under in vivo conditions, oat (Avena sativa L.) coleoptile, maize (Zea mays L.) coleoptile and pea (Pisum sativum L.) epicotyl sections were abraded so that exogenous buffers could penetrate the free space, and placed in buffered solutions of pH 3.5–6.5 without any preincubation. The extension, without auxin, was measured over the first 3 h. Experiments conducted in three laboratories produced similar results. For all three species, sections placed in buffer without pretreatment elongated at least threefold faster at pH 5.0 than at 6.0 or 6.5, and the rate elongation at pH 5.0 was comparable to that induced by auxin. Pretreatment of abraded sections with pH-6.5 buffer or distilled water adjusted to pH 6.5 or above gave similar results. We conclude that the pH present in the apoplast of auxin-treated coleoptile and stems is sufficiently low to account for the initial growth response to auxin.Abbreviations FS free space - IAA indole-3-acetic acid This research was supported by a grant from the National Adonautics and space Administration (NASA), NAGW 1394 to R.E.C., NASA grant NAGW-297 to M.L.E., and NASA grant NAG 1849 to D.L.R.     

Light-driven amino acid uptake in Streptococcus cremoris or Clostridium acetobutylicum membrane vesicles fused with liposomes containing bacterial reaction centers.

Reaction centers of the phototrophic bacterium Rhodopseudomonas palustris were introduced as proton motive force-generating systems in membrane vesicles of two anaerobic bacteria. Liposomes containing reaction center-light-harvesting complex I pigment protein complexes were fused with membrane vesicles of Streptococcus cremoris or Clostridium acetobutylicum by freeze-thawing and sonication. Illumination of these fused membranes resulted in the generation of a proton motive force of approximately -110 mV. The magnitude of the proton motive force in these membranes could be varied by changing the light intensity. As a result of this proton motive force, amino acid transport into the fused membranes could be observed. The initial rate of leucine transport by membrane vesicles of S. cremoris increased exponentially with the proton motive force. An H+/leucine stoichiometry of 0.8 was determined from the steady-state level of leucine accumulation and the proton motive force, and this stoichiometry was found to be independent of the magnitude of the proton motive force. These results indicate that the introduction of bacterial reaction centers in membrane vesicles by the fusion procedure yields very attractive model systems for the study of proton motive force-consuming processes in membrane vesicles of (strict) anaerobic bacteria.     

Regeneration of the arterial wall in microporous,compliant, biodegradable vascular grafts after implantation into the rat abdominal aorta

Summary The ultrastructure of a new type of vascular graft, prepared from a mixture of polyurethane (95 weight %) and poly-L-lactic acid (5 weight %), was examined six weeks after implantation into the abdominal aorta of rats. These microporous, compliant, biodegradable, vascular grafts function as temporary scaffolds for the regeneration of the arterial wall.Smooth muscle cells, covering the grafts, regenerated a neo-media underneath an almost completely regenerated endothelial layer (neo-intima). These smooth muscle cells varied in morphology from normal smooth muscle cells to myofibroblasts. They were surrounded by elastic laminae and collagen fibers.Macrophages, epithelioid cells, multinucleated giant cells, fibroblasts and capillaries were present in the disintegrating graft lattices. The epithelioid cells and multinucleated giant cells engulfed polymer particles of the disintegrating grafts.The regeneration of the endothelial and smooth muscle cells is similar to the natural response of arterial tissue upon injury. The presence of macrophages, epithelioid cells, multinucleated giant cells, fibroblasts and capillaries in the graft lattices resembles the natural response of tissue against foreign body implants. Both of these responses result in the formation of a neo-artery that possesses sufficient strength, compliance and thromboresistance to function as a small caliber arterial substitute.Supported by Grant nr. 82.042 from the Dutch Heart Foundation     

Some properties of human and bovine brain cathepsin B

Cathespin B has been purified 750-fold to apparent homogeneity from human and bovine brain cortex using ammonium sulfate fractionation (30–70%), chromatography on Sephadex G-100, CM-Sephadex C-50, and concanavalin A-Sepharose. Enzyme was assayed fluorometrically at pH 4.0 with pyridoxyl-hemoglobin in the presence of 1 mM DTT and 1 mM EDTA. Properties of the enzyme from the two sources proved to be similar. On disc PAGE the purified preparation produced two bands associated with proteinase activity that are due to existence of two multiple forms of brain cathepsin B with pI 6.1 and 6.8. The enzyme is completely inactivated by thiol-blocking reagents, leupeptin, E-64, and demands thiol compounds for its ultimate activity. Z-Phe-Ala-CHN₂ is a potent inhibitor of the enzyme (K _2nd=1280 M⁻¹s⁻¹) in contrast to Z-Phe-Phe-CHN₂ (K _2nd=264 M⁻¹s⁻¹). pH optimum in the reaction of hydrolysis of Pxy-Hb is 4.0–6.0,K _M(app.) =10⁻⁵ M. Cathepsin B splits azocasein: pH optimum 5.0–6.0,K _M(app.)=2.2·10⁻⁵ M, but inclusion of urea in the incubation medium depresses the azocaseinolytic activity of the enzyme 1.5-fold. It does not split Lys-NNap, Arg-NMec and is not inhibited by bestatin. The specific activity of brain cathepsin B with Z-Arg-Arg-NNapOMe at pH 6.0 is 10-fold higher than with Bz-Arg-NNap, Z-Gly-Gly-Arg-NNap is a poor substrate. With Z-Arg-Arg-NMec and Bz-Phe-Val-Arg-NMec the specific acitivity is 80 and 35%, respectively of that with Z-Phe-Arg-NMec. Special Issue dedicated to Dr. Eugene Kreps.     

Self-Renewal Capacity and Clonal Succession of Haemopoietic Stem Cells In Long-Term Bone Marrow Culture

Abstract. The CFU-s proliferative potential varied greatly during long-term cultivation. Most of the CFU-s in the cultures were represented by cells with low renewal capacity. Pre-CFU-s cells capable of producing multipotential colonies in methylcellulose, which contained CFU-s with a high proliferative potential, were identified in the culture. In cultivation of a mixture of cells of different karyotype their ratio changed rapidly from week to week. the findings were consistent with the hypothesis that haemopoietic stem cells are maintained in the culture by the products of a small number of clones which arise and decline in succession, and that pre-CFU-s, but not the CFU-s themselves, are clonogenic progenitors.     

Passive Transfer of Lambert-Eaton Myasthenic Syndrome in Mice: Decreased Rates of Resting and Evoked Release of Acetylcholine from Skeletal Muscle

Mice were injected for 1-2 months daily with 10 mg immunoglobulin G (IgG) from four patients with Lambert-Eaton myasthenic syndrome (LEMS); control mice were injected with pooled human IgG from normal donors. Gastrocnemius muscles were homogenised for the assay of acetylcholine (ACh), choline acetyltransferase (ChAT), and cholinesterase (ChE). The ACh, ChAT, and ChE contents of gastrocnemius muscles from "LEMS mice" were about the same as the control values, which were 180 pmol, 40 nmol X h-1 (37 degrees C), and 15 mumol X h-1 (37 degrees C), respectively. Hemidiaphragms were treated with an irreversible ChE inhibitor (Soman) and incubated at 20 degrees C for estimation of ACh release. Resting ACh release from experimental muscles was reduced by about 25% (P2 less than 0.05) and the release evoked by 3 s-1 nervous stimulation by 50% (P2 less than 0.05). On the other hand, 50 mM KCl-induced transmitter release was not abnormal in LEMS mice. The findings indicate that IgG antibody from patients with LEMS may bind to nerve terminal determinants that are involved in quantal and nonquantal ACh release.