Cytotoxic effect of unilamellar detergent dialysis liposomes on Trypanosoma brucei and Trypanosoma congolense bloodstream forms in vitro

Liposomes from egg yolk lecithin and egg yolk lecithin/ganglioside are cytotoxic for Trypanosoma brucei and Trypanosoma congolense bloodstream forms in vitro. The trypanocidal effect is influenced by the liposome age and concentration. This effect is diminished in the presence of whole blood in vitro and could not be observed in vivo. Freeze-fractured parasite membrane showed an intramembranous particle aggregation after incubation with liposomes. Liposomes from egg yolk lecithin kill trypanosomes more rapidly than do liposomes from egg yolk lecithin/cholesterol.     

Prostaglandin-induced enhancement of the in vitro anamenstic response

The ability of various prostaglandins (PGs) to affect the in vitro anamnestic immune response of keyhole limpet hemocyanin (KLH)-primed rabbit popliteal lymph node cells was investigated. Of the four PGs studied (PGA₁, PGE₂ and PGF_2α), PGE₁ was found to have a stimulatory effect, whereas PGA₁, PGE₂ and PGF_2α were ineffective in stimulating or inhibiting the in vitro anamnestic response. Under the conditions studied, a 3.5-fold increase in antibody production was obtained in PGE₁-treated, KLH-stimulated cultures. Maximum enhancement was obtained when 0.2 μg of PGE₁ were added at the time of culture initiation and were allowed to remain in contact with the lymph node cells for 24 hours.     

Nucleotide recognition seouence at the cleavage site of Haemophilus aegyptius II (Hae II) restriction endonuclease

We have determined the nucleotide sequence recognized by the restriction endonuclease Hae II from Haemophilus aegyptius which cleaves the simian virus 40 (SV40) DNA at a single specific site. By using terminal radioactive labeling of the cleavage site at both the 5′ and 3′-ends we have deduced the recognition sequence,

with elements of a two-fold rotational symmetry. The endonuclease produces staggered ends with protruding 3′-terminated single-strands, four nucleotides in length. In plasmid RSF 2124 DNA, which contains multiple Hae II cleavage sites, it was observed that the 5th nucleotide from the 3′ terminus is either a pdA or a pdG, indicating alternating recognition sequences.     

Pronase digestion of amino-acid binding components on the surface of Bacillus subtilis cells and minicells

The addition of 250 μg/ml pronase to either cells or minicells of Bacillus subtilis does not interfere with growth, macromolecular synthesis or maintenance of cell integrity. Radioactive amino acids such as proline or isoleucine taken up by cells or minicells are bound to surface components which prevent their release by washing. Pronase treatment causes the release of a significant percentage of these bound amino acids. In cells and minicells exposed to pronase before the addition of labeled amino acids, initial binding capacities are greatly reduced. These data suggest a new approach to the investigation of amino acid binding components on the surface of Bacillus subtilis.     

Ruizgenin,a new steroidal sapogenin diol from AgaveLecheguilla

From the leaves of Agavelecheguilla Torrey, two steroidal sapogenin diols have been isolated. Mass spectral, infra-red and nuclear magnetic resonance data of these two compounds showed them to be (25R) spirost-5-ene-2α, 3β-diol (yuccagenin) and (25R)-5β-spirostane-3β,6α-diol. The latter is a new compound to which the trivial name ruizgenin has been given.     

Recovery of megakaryocyte thromboxane production in vitro after aspirin inhibition

Megakaryocytes isolated in high purity from guinea pigs produced thromboxane B₂ in response to exogenously provided arachidonic acid. This production was inhibited by in vitro treatment with acetylsalicylic acid with a concentration response relationship similar to that seen in platelets. During in vitro culture, the aspirin-treated megakaryocytes recovered thromboxane synthetic ability. Following a lag of 12 hours, recovery of megakaryocyte thromboxane production resumed at a rate of 16% of control per day. This recovery was inhibited by the addition of cycloheximide to the culture medium.     

Outer membrane of Salmonella typhimurium: Reconstitution of sucrose-permeable membrane vesicles

Outer membrane vesicles were reconstituted from phospholipids, lipopolysaccharide, and outer membrane proteins isolated from Salmonella typhimurium. The vesicles appeared to be permeable to sucrose and other small oligosaccharides only when membrane proteins were added to the reconstitution system. The size of saccharides that could pass through the vesicle membranes was found to be close to the size of saccharides that penetrate through the intact outer membrane of S. typhimurium.     

Contractility of rat testicular seminiferous tubules in vitro: Prostaglandin F1α and indomethacin

The frequency of spontaneous in vitro contractions of seminiferous tubules of the rat appeared to be increased in a dose-dependent manner by prostaglandin F_1α. PGF_1α treatment increased the tonus of the smooth muscle cells in the wall of the tubules as indicated by a reduction in the diameter of the tubules. When the tubules were rinsed successively with fresh Tyrode's solution, the contractile frequency was diminished. Returning the original bathing medium to the tubules restored their contractile frequency, as did treatment of the rinsed tubules with PGF_1α (10⁻⁷ M). Pre-injecting the rats with indomethacin tended to reduce the contractile frequency of the extirpated tubules. Treating the tubules with a solution of indomethacin for 90 min. in vitro was more effective than pretreatment in vivo in reducing contractile frequency, but a combination of these two procedures produced the greatest inhibition. PGF_1α restored the contractile frequency of the indomethacin-treated tubules. Our results indicate that PGs modulate the in vitro contractility of the tubules.     

Photoaffinity labelling of juvenile hormone binding proteins in the cockroach Leucophaeamaderae

The synthesis and testing of several diazocarbonyl JH analogs (diazo JHA) which act as photoaffinity labels for insect juvenile hormone binding proteins are described. The best competitor, 10,11-epoxyfarnesyl diazoacetate, has been shown to irreversibly reduce [³H]-JH III binding to both ovarian and hemolymph JHBP from Leucophaeamaderae after irradiation at 254 nm for 20 seconds. No loss of activity was observed after incubation of JHBP and diazo JHA without irradiation. Protection from photoinactivation by diazo JHA II was achieved by the presence of an equimolar amount of JH III during the photolysis. Photoaffinity labeled proteins show loss of binding capacity without alteration of the binding affinity. This is the first example of the use of a photoaffinity label in the study of JH action on a molecular level, and may become a valuable tool in the elucidation of JH-receptor-chromatin interactions.     

Phosphorus-31 NMR of rat brain in vivo with bloodless perfluorocarbon perfused rat

Rat brain in vivo has been examined by ³¹p NMR under conditions of normal blood perfusion (hematocrit 38%) and under conditions in which a perfluorocarbon blood substitute, devoid of any phosphorus containing compounds, largely replaced the animal's normal blood supply (hematocrit 7%). These studies demonstate that 2,3-diphosphoglycerate does not — as has been suggested — contribute to, and thus does not interfere with, the ³¹p NMR analysis of rat brain in vivo. However, low intensity ³¹P resonances assigned to choline phosphate, glycerol 3-phosphorylethanolamine, and glycerol 3-phosphorylcholine are observed. “High energy phosphorus” metabolite levels show no marked change over two hours with perfluorocarbon blood substitution from those of the normal blood perfused animal. This supports use of perfluorocarbon media for tissue perfusion in vitro and for ¹⁹F NMR vascular imaging in vivo.     

Adenylate cyclases in Physarum polycephalum: Inhibition of a nuclear enzyme by polyamines

Two distinct adenylate cyclase enzymes have been found in Physarum polycephalum. One is derived from isolated nuclei and is potently inhibited by an equimolar combination of the three polyamines, putrescine, spermidine, and spermine. The second enzyme is particulate, derived from the cytoplasmic compartment, and is insensitive to inhibition by the polyamines. These observations support a potential role for the polyamines in the control of adenosine 3′,5′-monophosphate synthesis in P. polycephalum nuclei.     

Prostaglandin synthesis in rabbit graafian follicles in vitro. Effect of luteinizing hormone and cyclic AMP

We have demonstrated the capacity of isolated follicles from estrous rabbits to synthesize prostaglandins in vitro and to respond to gonadotropins added to the incubation medium with an increased accumulation of these lipids. The increase in both prostaglandins became apparent only after 5 hours of incubation. The effect was specific for hormones with LH activity and the threshold dose of LH appeared to be 0.005 μg/ml. In addition, we have shown that cyclic AMP (0.02 M) added to the incubation medium also increased prostaglandin in this in vitro system and appears to be a likely mediator of this action of LH.     

The antagonism by anti-inflammatory analgesics of prostaglandin F2α-induced contractions of human and rabbit myometrium in vitro

The anti-inflammatory analgesic drugs, aspirin, indomethacin, phenylbutazone, mefenamic acid, ibuprofen and flurbiprofen are shown to inhibit in a dose-dependent manner the force of contraction of isolated human pregnant myometrial strips which have been stimulated to contract by adding prostaglandin (PG) F_2α to the tissue bath. These drugs and also flufenamic acid and salicin show a similar antagonism of the action of PGF_2α with isolated rabbit non-pregnant myometrium. The ratio of the inhibitory concentration in vitro to the maximum plasma level after a normal dose in vivo suggests that phenylbutazone and possibly ibuprofen may be capable of inhibiting human uterine contractions in vivo. Patients who were treated with aspirin during induction of abortion using PGF_2α during the second trimester of pregnancy showed no significant change in the induction-abortion interval compared with patients not taking aspirin.     

Metabolism of progesterone and testosterone by a Bacillus sp.

Microbial transformations by a Bacillus sp. were employed as a means of preparing potentially important derivatives of progesterone and testosterone. Each microbial metabolite was subjected to structure elucidation employing ¹H and ¹³C nmr, mass spectral and cd analysis. Hplc was used for the determination of the percentages of the metabolites formed. The progesterone metabolites were characterised as 14-hydroxy-4-pregnene-3,20-dione (II), 14-hydroxy-5 α -pregnane-3,6,20-trione (III)., 11 α — hydroxy-5 α — pregnane-3, 6,20-trione (IV) and 11 α, 14-dihydroxy-4-pregnene-3,20-dione (V). The testosterone analogs were identified as 4-androstene-3,17-dione (VII), 17 β-hydroxy-5 α -androstene-3,6-dione (VIII), 14-hydroxy-4-androstene-3,17-dione (IX) and 14, 17 β-dihydroxy-4-androsten -3-one (X)₁. The availability of the metabolites enabled complete elucidation of their ¹³C nmr spectra.     

Synthesis of prostaglandin by reproductive tissue of the male house cricket, acheta domesticus

Whole reproductive tracts of male house crickets, Acheta domesticus, incubated with arachidonic acid and glutathione yielded an average of 17 ug of prostaglandin (PG) E₂/g of tissue. Biosynthesized PGE₂ was identified by mass spectroscopy. A compound with thin layer and gas chromatographic properties identical to PGE₁ was isolated from spermatophores of house crickets. This appears to be the first report of the occurrence of a PG in an insect species. The possible role of PG in insect reproduction is discussed.     

Inhibition of conjugation and cell division in Tetrahymena pyriformis by tunicamycin: A possible requirement of glycoprotein synthesis for induction of conjugation

Tunicamycin, a glucosamine-containing antibiotic inhibited the conjugation process of Tetrahymena pyriformis. Sexual pairing was prevented completely when 1.5 μg/ml of tunicamycin was added to a mixture of the two mating types. Tunicamycin caused preferential inhibition of glycoprotein synthesis in Tetrahymena pyriformis. At 1.5 μg/ml and 6 μg/ml tunicamycin inhibited by 40% and 60% respectively [³H]-glucosamine incorporation into material precipitated by ethanol, while it did not affect [¹⁴C]-leucine incorporation. Cell division was also inhibited when the drug was added either to the regular growth medium or to the starvation medium.     

Effects of epinephrine and oxytocin on the release of prostaglandin F from the rat uterus in vitro

Isolated uteri from rats with regular 4-day cycles were incubated in Krebs-Ringer bicarbonate buffer and the release of PGF into the medium was measured by radio-immunoassay after extraction of the incubation medium with ethyl acetate at pH 3.0–3.5. PGF was produced from endogenous precursors and accumulated in equal amounts in the medium during two successive 60 min periods on each day of cycle, but the magnitude of the production varied significantly during the cycle, being greatest in estrus. Oxytocin in doses up to 500 mU/ml had no effect on PGF accumulation in the incubation period at any stage of the cycle, while epinephrine (10⁻³) greatly stimulated PGF release from the estrous uterus but had no effect on PGF release from the diestrous uterus. Phentolamine, an α-blocking agent, had no effect on the epinephrine-induced release of PGF, while propranolol, a β-blocking agent, not only prevented the increase in PGF production induced by epinephrine but also reduced the basal release of PGF by the estrous uterus. Since oxytocin contracts and epinephrine relaxes the nonpregnant rat uterus both in vivo and in vitro, it is unlikely that the effects of these two compounds on uterine contractility are mediated by the release of PGF_2α.     

Phenolic 9,10-secosteroids as products of the catabolism of bile acids by a Pseudomonas sp.

The obligate aerobe, Pseudomonas putida ATCC 31752, efficiently utilises bile acids as a source of carbon and energy for growth and maintenance. When aeration is considerably restricted, a consequence to the catabolism of the bile acids in a fermentor is an accumulation of certain steroidal catabolites. Evidence is presented to show that among these are hydroxy-9,10-seco-1,3,5(10)-androstratriene-9,17-diones and those from four of the common bile acids, cholic, chenodeoxycholic, hyodeoxycholic and deoxycholic acids have been isolated and their structures determined. The product of catabolism of hyodeoxycholic acid appears to exist in a hemi-acetal form which readily forms an acetal during isolation procedures. All but one of these are described for the first time.     

Progesterone in the uterus. VI. On the question of the in vitro progesterone metabolism in human endometrium and myometrium

Human endometrial and myometrial tissue pieces were incubated with radioactively labeled progesterone in nutrient medium for 20 min., 1 hr and 2 hrs. The only compound extracted from the tissue pieces and the nutrient fluids was identified to be progesterone by TLC, chemical reactions and crystallization experiments. Radiometabolites could not be detected in the tissue pieces and in the nutrient fluids under the experimental conditions applied ( 10^?7 M 1,2-³H-progesterone in the incubation medium). This result is comparable with recent findings on the in vitro progesterone metabolism by rat uterine tissue.     

Growth of Dioscorea deltoidea at high sugar concentrations

Dioscorea deltoidea cell suspension cultures were grown at initial sucrose concentrations of 35 to 200 g/L. The growth rates were similar (about 0.50 day^–1) with all of the initial sugar concentrations examined. The ratio of fresh weight to dry weight of cells was dependent on the initial sugar concentration, however, it remained fairly constant as long as the sugar was present in the growth medium. These results are different from results recently published, claiming that the growth rate of D. deltoidea cells is dependent on sugar concentration and the fresh weight to dry weight ratio increases throughout growth.