NMR Studies of Simple Molecules on Metal Surfaces

In recent years, improvements in the sensitivity of nuclear magnetic resonance have made it possible to detect progressively smaller numbers of nuclei. Experiments and studies previously thought to be impractical can now be undertaken, for example, the study of phenomena at surfaces. Nuclear magnetic resonance has been applied to study simple molecules (carbon monoxide, acetylene, and ethylene) adsorbed on metal surfaces (ruthenium, rhodium, palladium, osmium, iridium, and platinum). The metals, in the form of clusters 10 to 50 angstroms in diameter, supported on alumina, are typical of real catalysts. The experiments provide information about the bonding of the molecules to the metal, the structures the molecules assume after adsorption, the motion of molecules on the surface, the breakup of molecules induced by heating, and the products of such breakup.

Quantitative and qualitative analyses of serum antibodies elicited in adults by Haemophilus influenzae type b and pneumococcus type 6A capsular polysaccharide-tetanus toxoid conjugates

Covalent binding to immunogenic proteins increases the immunogenicity of the capsular polysaccharides of Haemophilus influenzae type b (Hib) and pneumococcus type 6A (Pn6A). Conjugates composed of Hib, Pn6A, or the cross-reacting Escherichia coli K100 covalently bound to tetanus toxoid (TT) were injected into young adult volunteers. Local reactions were common and were probably due to Arthus reactivity mediated by the preexisting antibodies reacting with the TT component of the conjugates. Fever occurred in about 10% of the volunteers after the first injection; no volunteers had fever after the second injection. Similar levels of Hib or Pn6A antibodies were elicited by either 50- or 100-micrograms doses or by concurrent injection of two different conjugates (Hib-TT and Pn6A-TT or Hib-TT and K100-TT). The Hib-TT elicited about a 180-fold increase in Hib antibodies, and the Pn6A-TT conjugate elicited about an 8-fold increase in Pn6A antibodies after one injection. Booster reactions were not elicited in adults; similar levels of antibodies in the five experimental groups suggested that the responses elicited by the conjugates were maximal. A one-way cross-reaction was noted as Pn6A conjugates elicited rises of Hib antibodies in 13 of 20 volunteers; only 4 of 59 volunteers immunized with Hib-TT had increases in Pn6A antibodies. The preimmunization Hib antibodies were composed of immunoglobulin M (IgM), IgA, and IgG. The postimmunization sera showed an increase in all three isotypes; the elevation of the IgG was the highest of the three isotypes. Conjugate-induced antibodies to both the polysaccharide and TT exerted biological activities that have been correlated with immunity. Adsorption of the Hib-TT onto aluminium hydroxide resulted in higher levels and an earlier Hib antibody response in infant rhesus. These results encourage the evaluation of Hib and Pn6A conjugates in human children and infants.

Induction of increased antibody responses to pneumococcal type 19F polysaccharide by Klebsiella polysaccharide

The level of antibody to pneumococcal 19F polysaccharide (PS) was studied in the serum of mice inoculated with klebsiella K2 PS or pneumococcal 19F PS or both. The serum antibody levels and the IgM plaque-forming-cell (PFC) response after immunization were higher in mice given both K2 PS and 19F PS than in mice of a control group given 19F PS alone. This immune response was also higher than the sum of PFC production in mice given 19F PS or K2 PS separately. Thus, K2 PS produced the cross-reactive antibody to 19F PS and also enhanced the magnitude of the antibody response to 19F PS. This response appeared to be specific for the 19F PS. The resulting high levels of antibody to pneumococcal 19F persisted for eight weeks after the administration of K2 PS and 19F PS. Animals immunized with both type 3 PS and K2 PS did not show an increased antibody response to pneumococcal type 3 PS. Klebsiella K-O3 antigen also stimulated the immune response to 19F PS. Higher immunologic responses to 19F PS were also induced in nude mice injected with the cross-reacting K2 PS or K47 PS and 19F PS. The ability to stimulate an antibody response to 19F PS by administering both K2 PS and 19F PS could not be transferred with spleen cells obtained from mice given both K2 PS and 19F PS.

Escherichia coli 6S RNA gene is part of a dual-function transcription unit

The gene coding for the metabolically stable 6S RNA of Escherichia coli has been cloned, sequenced, and partially characterized in expression analyses. The DNA sequence results confirm the accuracy of the previously established RNA sequence and, with genomic hybridization data, reveal that there is only one copy of the 6S DNA in the chromosome. Consistent with its relaxed mode of expression, the promoter region of the 6S RNA gene was found to lack the hypothetical GC-rich discriminator domain common to other stable RNA genes under stringent control. The sequence results also revealed the occurrence of a 540-base-pair open reading frame immediately downstream from the 6S RNA coding region. Results from the expression analyses show that the protein and RNA coding regions are cotranscribed in vitro and that the open reading frame is translated in vivo.

Nickel inhibition of calcium release from subsarcolemmal calcium stores of molluscan smooth muscle

Replacement of calcium in artificial sea water (ASW) by nickel causes a loss of calcium at a single exponential rate (tau = 23.2 min) and the loss of contracture response to acetylcholine (ACh) in the anterior byssus retractor muscle of Mytilus edulis L. The ACh contracture response is lost at two rates; 93% of the ACh contracture response is lost rapidly (tau = 7.43 min) and the remaining 7% of ACh contracture response is lost slowly (tau = 66.6 min). The rapid phase of loss of ACh contracture corresponds to the rapid exponential uptake of nickel (tau = 6.5 min). The loss of ACh contracture response is attributed to the displacement of calcium from membrane release sites by nickel. In O-Ca-Mg ASW, the ACh contracture responses are well maintained over a 35-min period when stimulated by ACh every 5 min. Stimulation by ACh after 1, 20 and 40 min in O-Ca-Mg ASW results in a reduction of ACh contracture response to 15% of the response in Ca ASW. Similar treatment in O-Ca-Ni ASW reduces the ACh contracture response to 4%. Potassium and caffeine contracture responses at 1, 20 and 40 min in O-Ca-Mg ASW are reduced to 25 and 28%. Similar treatment in O-Ca-Ni ASW produces a block of potassium contracture response and reduces caffeine contracture response to 3%. Our 45Ca uptake data demonstrate that calcium influx is not required for the ACh contracture responses of anterior byssus retractor muscle.

The effect of a medicinal Chinese herb on platelet function

We investigated the effect of the Chinese herb Injectio Salvia Miltiorrhizae (ISM) on human platelet function in vitro. ISM inhibited platelet aggregation and serotonin release induced by either ADP or epinephrine in a dose dependent manner. This effect of ISM was observed with both gel-filtered platelets (ID50 = 8-30 micrograms ISM/ml gel-filtered platelets) and platelets in plasma (ID50 = 400-900 micrograms ISM/ml of platelet-rich plasma). The active molecule(s) in ISM was heat stable, resistant to acid, base and proteolysis and fractionated on Sephadex 6-25 at MW approximately 280. ISM did not interact with the platelet alpha-adrenergic receptor, but increased cAMP in intact platelets. The results are consistent with the concept that ISM inhibition of platelet aggregation and release is mediated by an increase in platelet cAMP. The exact mechanism whereby ISM increases platelet cAMP appears to be that of inhibition of cyclic AMP phosphodiesterase. The effect of ISM on platelet function is one mechanism which might explain the therapeutic effect of ISM in experimental and clinical coronary artery disease.

The Effect of a Medicinal Chinese Herb on Platelet Function

We investigated the effect of the Chinese herb Injectio Salvia Miltiorrhizae (ISM) on human platelet function in vitro. ISM inhibited platelet aggregation and serotonin release induced by either ADP or epinephrine in a dose dependent manner. This effect of ISM was observed with both gel-filtered platelets (ID50 = 8–30 μg ISM/ml gel-filtered platelets) and platelets in plasma (ID50 = 400–900 μg ISM/ml of platelet-rich plasma). The active molecule(s) in ISM was heat stable, resistant to acid, base and proteolysis and fractionated on Sephadex 6-25 at MW ~ 280. ISM did not interact with the platelet α-adrenergic receptor, but increased cAMP in intact platelets. The results are consistent with the concept that ISM inhibition of platelet aggregation and release is mediated by an increase in platelet cAMP. The exact mechanism whereby ISM increases platelet cAMP appears to be that of inhibition of cyclic AMP phosphodiesterase. The effect of ISM on platelet function is one mechanism which might explain the therapeutic effect of ISM in experimental and clinical coronary artery disease.

Haloperidol produces hypothermic effects in rats

Intraperitoneal administration of either haloperidol or chlorpromazine produced hypothermia both in the cold (8 degrees C) and at room temperature (22 degrees C). The hypothermia was brought about both by a decrease in metabolic heat production and an increase in the cutaneous temperature of tail and foot skin. However, at a higher temperature (29 degrees C), there were no changes in rectal temperature and other thermoregulatory responses.

Effects of apomorphine on thermoregulatory responses of rats to different ambient temperatures

Either systemic or central administration of apomorphine produced dose-related decreases in rectal temperature at ambient temperatures (Ta) of 8 and 22 degrees C in rats. At Ta = 8 degrees C, the hypothermia was brought about by a decrease in metabolic rate (M). At Ta = 22 degrees C, the hypothermia was due to an increase in mean skin temperature, an increase in respiratory evaporative heat loss (Eres) and a decrease in M. This increased mean skin temperature was due to increased tail and foot skin temperatures. However, at Ta = 29 degrees C, apomorphine produced increased rectal temperatures due to increased M and decreased Eres. Moreover, the apomorphine-induced hypothermia or hyperthermia was antagonized by either haloperidol or 6-hydroxydopamine, but not by 5,6-dihydroxytryptamine. The data indicate that apomorphine acts on dopamine neurons within brain, with both pre- and post-synaptic sites of action, to influence body temperature.