Lipopolysaccharide (LPS) from Brucella abortus is less toxic than that from Escherichia coli, suggesting the possible use of B. abortus or LPS from B. abortus as a carrier in vaccines.

Brucella abortus may be useful as a component of vaccines. This is because it possesses several unique properties as a carrier that enable it to stimulate human B cells even in the relative absence of T cells. Human immunodeficiency virus type 1 proteins conjugated to B. abortus could induce neutralizing antibodies against human immunodeficiency virus type 1. Recently we showed that the characteristics of lipopolysaccharide (LPS) derived from B. abortus are similar to those of the whole bacterium in that the LPS acts as a T-independent type 1 carrier in mice. In this study we wanted to determine whether LPS derived from B. abortus is associated with the adverse effects seen with other bacterial endotoxins. LPS purified from B. abortus by butanol extraction was shown to have less than 2% (wt/wt) contamination by protein and less than 1% (wt/wt) contamination by nucleic acids and to contain 1% (wt/wt) ketodeoxyoctanic acid. Compared with LPS derived from Escherichia coli, B. abortus LPS was 10,000-fold less potent in eliciting fever in rabbits, 268-fold less potent in killing D-galactosamine-sensitized mice, and 1,400-fold and 400-fold less potent in inducing interleukin-1 beta and tumor necrosis factor alpha production, respectively. These results suggest that B. abortus LPS is much less likely than the LPS from E. coli to evoke endotoxic shock; therefore, it may be feasible to incorporate B. abortus as a component of vaccines.     

Comparative activity of teicoplanin and vancomycin against 400 penicillin susceptible and resistantStreptococcus pneumoniae

The MICs of teicoplanin and vancomycin were determined for 400 penicillin-susceptible and -resistant strains ofStreptococcus pneumoniae isolated during a multicenter study in 1992. Teicoplanin displayed a four-fold better activity than vancomycin, with modal MICs of these agents being 0.06 and 0.25 µg/ml, respectively. These data warrant further studies with teicoplanin in the treatment of pneumococcal infections.J. Akli, Centre Hospitalier Général, 41016 Blois Cédex; P. Allouch, Hôpital André Mignot, 78157 Le Chesnay Cédex; C. Bébéar, Centre Hospitalier Pellegrin-Tripode, 33076 Bordeaux Cédex; P. Blondel, Centre Hospitalier Général, 93205 Saint-Denis Cédex 1; A. Boisivon, Centre Hospitalier Général, 78104 Saint-Germain en Laye; J.C. Burdin, Hôpital Central, 54035 Nancy Cédex; H. Chardon, Centre Hospitalier Général, 13616 Aix en Provence Cédex; A. Coupry, Nouvel Hôpital de Fleyrat, 01012 Bourg-en-Bresse Cédex; J.C. Croix, Centre Hospitalier Général, 10003 Troyes Cédex; G. Dorche, Hôpital Bellevue, 42043 Saint-Etienne Cédex; P. Fiévet, Centre Hospitalier, 59507 Douai Cédex; F. Geffroy, Centre Hospitalier René Laënnec, 29107 Quimper Cédex; P. Geslin, Centre Hospitalier Intercommunal, 94010 Créteil; M.L. Grillot, Hôpital Général, 76083 Le Havre Cédex; B. Hautefort, Centre Hospitalier Général, 13697 Arles Cédex; M. Larrouy, Centre Hospitalier Intercommunal de la Côte Basque, 64109 Bayonne; H. Lefrand, Hôpital Henri Duffaut, 84902 Avignon Cédex 9; J.F. Lemeland, Hôtel-Dieu, 76000 Rouen; J.M. Libert, Centre Hospitalier Mane-Lannelongue, 92350 Le Plesssis-Robinson; A. Marmonier, Centre Hospitalier, 72037 Le Mans Cédex; M. Melon, Centre Hospitalier Général, 64011 Pau Cédex; M.H. Nicolas, Hôpital Ambroise Paré, 92104 Boulogne; J.C. Reveil, Hôpital Manchester, 08011 Charleville-Mézières Cédex; Y. Rio, Hôpital Notre Dame de Bon Secours, 57038 Metz Cédex; R. Sanchez, Hôpital Général, 24019 Périgueux Cédex; A. Sédaillan, Centre Hospitalier, 74011 Annecy Cédex, France.     

Relationship of resting blood pressure and heart rate to experienced anger and expressed anger

Forty-five nonmedicated subjects rated on analog scales the anger they experienced at home and at work (Experienced Anger). They also rated the extent to which others were aware of their anger (Expressed Anger) and the extent to which anger had been expressed in their families or origin (Family Expressed Anger). They were then physiologically monitored during a 2-min relaxation period that followed habituation to the laboratory setting. For the group as a whole, Expressed Anger was inversely related to systolic (SBP) and diastolic (DBP) blood pressure while Family Expressed Anger was inversely related to SBP only. When the sample was divided into normotensive and hypertensive subgroups, the normotensives showed significant associations between Experienced Anger and SBP, Expressed Anger and DBP, and Family Expressed Anger and SBP. The hypertensive subgroup showed no significant associations. Both males and females showed a significant association between Expressed Anger and DBP, but only females showed this relationship with SBP. It is concluded that coping with anger by conscious inhibition of its expression is associated with increases in both systolic and diastolic blood pressure.     

The BPV-1 E5 oncoprotein expressed in Schizosaccharomyces pombe exhibits normal biochemical properties and binds to the endogenous 16-kDa component of the vacuolar proton-ATPase

The 44-amino-acid E5 oncoprotein of bovine papillomavirus type 1 transforms immortalized murine fibroblast cell lines. This highly hydrophobic protein forms homodimers, localizes to intracellular membrane compartments (including the Golgi apparatus), and forms a complex with the 16-kDa membrane-embedded constituent (16k) of the vacuolar proton-ATPase. To develop a system for the genetic and biochemical analysis of the E5/16k interaction, the E5 gene was cloned into a new vector which was designed for expression in the fission yeast Schizosaccharomyces pombe. The E5 protein synthesized in this system dimerized normally and bound to endogenous and overexpressed S. pombe 16k protein. Comparison of the S. pombe and mammalian 16k proteins showed strong conservation in carboxyl-terminal amino acids but greater variation in the amino-terminal sequences, suggesting that E5 was interacting with the 16k carboxyl domains. Finally, a new protein epitope tag is described which permitted for the first time the coprecipitation of E5 with antibodies directed against the 16k protein.     

Identifying candidate causal variants responsible for altered activity of the ABCB1 multidrug resistance gene

The difficulty of fine localizing the polymorphisms responsible for genotype-phenotype correlations is emerging as an important constraint in the implementation and interpretation of genetic association studies, and calls for the definition of protocols for the follow-up of associated variants. One recent example is the 3435C>T polymorphism in the multidrug transporter gene ABCB1, associated with protein expression and activity, and with several clinical conditions. Available data suggest that 3435C>T may not directly cause altered transport activity, but may be associated with one or more causal variants in the poorly characterized stretch of linkage disequilibrium (LD) surrounding it. Here we describe a strategy for the follow-up of reported associations, including a Bayesian formalization of the associated interval concept previously described by Goldstein. We focus on the region of high LD around 3435C>T to compile an exhaustive list of variants by (1) using a relatively coarse set of marker typings to assess the pattern of LD, and (2) resequencing derived and ancestral chromosomes at 3435C>T through the associated interval. We identified three intronic sites that are strongly associated with the 3435C>T polymorphism. One of them is associated with multidrug resistance in patients with epilepsy (chi2 = 3.78, P = 0.052), and sits within a stretch of significant evolutionary conservation. We argue that these variants represent additional candidates for influencing multidrug resistance due to P-glycoprotein activity, with the IVS 26+80 T>C being the best candidate among the three intronic sites. Finally, we describe a set of six haplotype tagging single-nucleotide polymorphisms that represent common ABCB1 variation surrounding 3435C>T in Europeans.     

Hyperglycemia potentiates H(2)O(2) production in adipocytes and enhances insulin signal transduction: potential role for oxidative inhibition of thiol-sensitive protein-tyrosine phosphatases

Insulin signal transduction in adipocytes is accompanied by a burst of cellular hydrogen peroxide (H(2)O(2)) that facilitates insulin signaling by inhibiting thiol-dependent protein-tyrosine phosphatases (PTPs) that are negative regulators of insulin action. As hyperglycemia is associated with increased cellular reactive oxygen species, we postulated that high glucose conditions might potentiate the H(2)O(2) generated by insulin and modulate insulin-stimulated protein phosphorylation. Basal H(2)O(2) generation was increased threefold in differentiated 3T3-L1 adipocytes by growth in 25 mM glucose versus 5 mM glucose. High glucose increased the sensitivity of the insulin-stimulated H(2)O(2) signal to lower concentrations of insulin. Basal endogenous total PTP activity and the activity of PTP1B, a PTP implicated in the negative regulation of insulin signaling, were reduced in high glucose conditions, and their further reduction by insulin stimulation was more enhanced in high versus low glucose medium. Phosphorylation of the insulin receptor, IRS-1, and Akt in response to insulin was also significantly enhanced in high glucose conditions, especially at submaximal insulin concentrations. In primary rat adipocytes, high glucose increased insulin-stimulated H(2)O(2) production and potentiated the oxidative inhibition of total PTP and PTP1B activity; however, insulin signaling was not enhanced in the primary cells in high glucose apparently due to cross-regulation of insulin-stimulated protein phosphorylation by activation of protein kinase C (PKC). These studies indicate that high glucose can enhance insulin stimulated H(2)O(2) generation and augment oxidative PTP inhibition in cultured and primary adipocytes, but the overall balance of insulin signal transduction is determined by additional signal effects in high glucose, including the activation of PKC.     

The effects of stress and caffeine on hypertensives

Eighteen male hypertensives on diuretic medication between the ages of 37 and 60 were studied in a double-blind, randomized, crossover design under three conditions: 200 mg of caffeine and mental arithmetic; placebo and mental arithmetic; and 200 mg of caffeine alone. Systolic and diastolic blood pressure, heart rate, and skin conductance were recorded. During rest, caffeine compared to placebo increased blood pressure by 8/6 mm Hg, but had no effect on heart rate or skin conductance. During mental arithmetic, the combined effect of mental stress and caffeine led to a further increase of 17/7 mm Hg, reaching a pressure level of 163/100 mm Hg. Heart rate and skin conductance were increased above their prior caffeine levels. There were no significant differences between the blood pressure response to mental arithmetic with caffeine and that response to mental arithmetic with a placebo, which may have been due to the fact that the hypertensives were already responding at ceiling level during the mental stressor.     

Thymic germinal centres in myasthenia gravis: a correlative study

The density of germinal centres in the thymic medulla in twenty-three cases of myasthenia gravis correlated inversely with age but did not correlate with sex, the duration of symptoms of myasthenia gravis, the presence of thymoma, or the result of tests for antibody to striated muscle and thymic epithelial cells.

The number of germinal centres formed in lymphoid tissues during an immune response in man is known to decrease with increasing age and this probably applies to autoimmune reactions. The inverse correlation of thymic germinal centres and age in myasthenia gravis is thus consistent with an autoimmune reaction occurring in the thymus in all cases of myasthenia gravis.