Development of heart cells in culture: studies using an affinity purified antibody to a myosin light chain

Cultured neonatal rat heart cells can be used to study the factors that regulate cardiac contractility and myocyte development in vitro. An antibody to the 26,000 dalton light chain of myosin (MLC1), has been produced and purified on a Sepharose 4B affinity column prepared with rat heart myosin. When primary cultures of myocytes are studied by indirect immunofluorescence using this antibody a predictable pattern of myofibrillar structure is observed to develop over 72 h. This myosin cytoskeleton is highly organized and the myosin fibrils exhibit cross striations. The antibody does not stain non-muscle heart cells and there is no evidence for myocyte division in culture. The qualitative immunofluorescent pattern of myosin organization is the same in both spontaneously beating and in non-contracting cells.     

A benzodiazepine antagonist inhibits the cerebral metabolic and respiratory depressant effects of fentanyl

It is reported that benzodiazepines such as diazepam will stimulate the opiate receptor system and that B-carboline drugs, which are benzodiazepine antagonists, may interact with opiate receptors directly. The ability of 3-hydroxymethyl-B-carboline (3-HMC) to antagonize several parameters of fentanyl anesthesia was tested here in rats. Fentanyl (25 and 100 micrograms/kg iv) produced dose dependent depression of cerebral blood flow (CBF), measured by radioactive microspheres, and cerebral oxygen consumption (CMRO2). These effects were significantly inhibited by 10 mg/kg 3-HMC iv. To test for the specificity of this effect, 3-HMC was also given to rats ventilated with inspire concentrations of 2% halothane. Halothane depressed CMRO2 equally in 3-HMC and vehicle treated rats, indicating no significant effect of the benzodiazepine antagonist. Blood pressure was increased in 3-HMC compared to vehicle treated animals during both fentanyl and halothane anesthesia. CBF was increased in 3-HMC vs vehicle treated rats during halothane anesthesia but this could be accounted for by the elevated blood pressure and lack of cerebral autoregulation rather than a direct cerebrovascular effect. 3-HMC decreased the sleep time and respiratory depressant effects of fentanyl but enhanced the analgesic effects of the opiate, as measured by time to respond to a hot plate stimulus. These results indicate that 3-HMC has the ability to specifically antagonize fentanyl anesthesia. These effects may be produced by an action of 3-HMC at the benzodiazepine receptor and/or by an action of the B-carboline at opioid receptors.     

Extracellular lumazine from aggregating Dictyostelium discoideum cells. Influence of pH on its fluorescence

Lumazine has been demonstrated to be one of the two main compounds responsible for the extracellular fluorescence linked with the aggregation ability of Dictyostelium discoideum, strain Ax-2. The other compound, also having lumazine properties, is, however, different from the 7-hydroxylumazine proposed previously. The influence of pH on the fluorescence of lumazine was studied. The possible use of extracellular pteridines as pH markers was stressed and a method for the determination of the amount of "lumazine equivalents" in the extracellular medium of aggregating D. discoideum cells is elaborated.     

Human autologous rosettes. IV. Their relation with interleukin 2 activity production and natural killer cells in cancer patients

Peripheral blood lymphocytes (PBL) of solid-tumor-bearing cancer patients produced a lower interleukin 2 (IL-2) activity after lectin stimulation than did those from normal subjects. Moreover natural killer (NK) cell activity and autologous rosette forming (ARF) cell rate are found significantly correlated with IL-2 production in these patients. No direct relation is observed between ARF cell ratio and NK cell activity in a given patient. A central role for IL-2 in cancer patient immune dysfunctions is suggested. Two lines of pathogenetic mechanisms are documented. First, PBL exhibited cellular function defects, namely, autologous receptor expression, IL-2 production, and NK activity. Second, these dysfunctions involved, at least partly, plasma factors. The possibility of specific deficiency, (e.g., thymic factors) is not documented. Conversely it is demonstrated that patient plasma contain immunosuppressive factor(s) that block(s) IL-2 production and ARF cell expression. Involvement of ARF cell receptor in T-cell activation is discussed.     

Enhancing effects of monocytes on modulation of a lymphocyte membrane antigen

Redistribution, or modulation, of some cell surface antigens occurs in the presence of specific antibody. The phenomenon of antigenic modulation may therefore affect the use of antibodies as therapeutic agents. This study was undertaken to investigate modulation of the 65,000 dalton T65 antigen, present on normal and malignant T cells and some malignant B cells, which is recognized by the monoclonal antibody T101. To induce cell surface antigenic modulation, normal or leukemic lymphoid cells were cultured in the presence of monoclonal antibody T101 for 3-hr periods. Removal of monocytes from mononuclear cell preparations resulted in significantly lower degrees of T65 antigenic modulation. The degree of antigenic modulation could be increased by adding monocytes back to monocyte-depleted lymphocyte suspensions. Furthermore, maximal modulation occurred in the presence of monocytes at T101 concentrations that were 3 logs lower than in the absence of monocytes. The enhancing effect of monocytes was dependent on the Fc portion of the T101 antibody molecule, and presumably was mediated by cross-linking of antigen-antibody complexes on the surface membrane of the modulating cell by Fc receptors present on monocytes. Further experiments performed to examine the characteristics of this enhancement of antigenic modulation by monocytes indicated that autologous as well as allogeneic monocytes were effective, indicating that the enhancing phenomenon was not dependent upon recognition of major histocompatibility antigens. Viable monocytes were required, but pretreatment of monocytes with sodium azide to inhibit energy production, or indomethacin to inhibit prostaglandin synthesis had no effect on this phenomenon. Polymorphonuclear leukocytes did not mediate similar enhancement, although monocytic and myeloid cell lines U937, THP-1, and HL-60 did. Spent culture medium from modulated cultures and preparations containing IL 1 activity did not enhance modulation of the T65 surface antigen on lymphocytes, suggesting that direct contact between lymphocytes and monocytes is required to mediate the effect. The finding that leukemic cells from patients with CLL undergo modulation of the T65 antigen to a much lower degree in vitro than observed in vivo, and that this difference can be overcome by the addition of monocytes, suggests that monocytes or the reticuloendothelial system may augment antigenic modulation in vivo.     

Studies on ultrastructure and host range of aChlorella attacking virus

Summary A tail-less polygonal virus with a prominent capsid of about 140–150 nm in diameter and about 14–15 nm in thickness has been isolated from a freshwater pond. It shows a marked host specificity in attacking only an endosymbioticChlorella sp. isolated fromParamecium bursaria (Ciliata). Viral replication starts in the algal cytoplasm and both autospores and old cells are lysed. The ecology of the virus in the freshwater habitat is discussed. Screening tests for further phycoviruses were not successful.     

Spontaneous cell-mediated cytolysis by peripheral blood cells obtained from whole-body chronically irradiated beagle dogs

The level of natural killer (NK) activity of continuously gamma-irradiated (whole body) beagle dogs and their nonirradiated controls was studied. For analytical purposes, irradiated dogs were segregated into groups according to their clinical status: clinically normal, hypocellular, or with acute non-lymphocytic leukemia. Since unirradiated control animals exhibited a wide range of NK responses, the data from each irradiated animal were compared to its own age-matched or litter-matched unirradiated control. Of the eight clinically normal irradiated dogs (median = 146% activity of control) only one animal had a NK activity lower than that of its control. The hypocellular group (n = 5, median = 21.8% of control) and the leukemic group (n = 4, median = 52.5% of control) each contained one responder with higher activity than its control. The difference between the percentage of control of the clinically normal and clinically abnormal dogs was found to be significant (P less than 0.05). There is a negative correlation between the NK results obtained and the total accumulated dose of radiation at the time of sampling (correlation coefficient = -0.739, P less than 0.01), suggesting a radiation effect upon natural killer activity, which is evidence by enhancement at lower doses and depression at higher doses of irradiation.     

Le genisteto-carlinetum macrocephalae ass. nov. De l'étage montagnard et le ligusticetum corsici ass. nov. De l'étage subalpin des massifs du cinto et du campotile orientale

Sans résuméJe tiens à remercier M. le Dr. J. Braun-Blanquet de la généreuse hospitalité qu'il m'a offerte à la S.I.G.M.A. et des précieux conseils qu'il m'a dispensés pour la définition de ces associations. C'est la raison pour laquelle il m'a paru nécessaire de l'associer à l'une des Associations originales que j'ai décrites.Je suis également reconnaissant à mes amis M. et G. Roux d'avoir permis le traitement de mes données floristiques par l'analyse factorielle des correspondances.     

Le Genisteto-Carlinetum macrocephalae ass. nov. de l'étage montagnard et le Ligusticetum corsici ass. nov. de l'étage subalpin des Massifs du Cinto et du Campotile orientale

Sans résuméJe tiens à remercier M. le Dr.J. Braun-Blanquet de la généreuse hospitalité qu'il m'a offerte à la S.I.G.M.A. et des précieux conseils qu'il m'a dispensés pour la définition de ces associations. C'est la raison pour laquelle il m'a paru nécessaire de l'associer à l'une des Associations originales que j'ai décrites.Je suis également reconnaissant à mes amisM. et G. Roux d'avoir permis le traitement de mes données floristiques par l'analyse factorielle des correspondances.