Li+ inhibition of membrane current responses to epinephrine in guinea-pig ventricular cells

Membrane currents of guinea-pig ventricular myocytes were recorded using the whole-cell voltage clamp method. The epinephrine-induced increase in Ca²⁺ current (2.9±0.5 times control) was reduced (1.8 ±0.3 times) by replacing Na⁺ with Li⁺ in the bathing solution. In addition, 0.5 M epinephrine increased a time-independent membrane conductance in the Na⁺ external solution, having a reversal potential of –19 ±3 mV (epinephrine-induced current). In the Li⁺ external solution, however, 0.5 M epinephrine failed to induce the epinephrine-induced current. The findings are consistent with the reported Li⁺ inhibition of GTP-binding protein and/or adenylate cyclase.     

C3 degradation products (C3d) in normal pregnancy.

Plasma C3 degradation products (C3d) were measured in 65 normal pregnancies and compared with those of non-pregnant women. No significant difference was detected between the two groups, although a difference had been previously reported. Plasma C3d estimations give an indication of complement activation and may be used as an indicator of disease activity in patients with systemic lupus erythematosus (SLE), irrespective of pregnancy.     

Modulation of Whole-Cell Currents in Plasmodium Falciparum-Infected Human Red Blood Cells by Holding Potential and Serum

Recent electrophysiological studies have identified novel ion channel activity in the host plasma membrane of Plasmodium falciparum -infected human red blood cells (RBCs). However, conflicting data have been published with regard to the characteristics of induced channel activity measured in the whole-cell configuration of the patch-clamp technique. In an effort to establish the reasons for these discrepancies, we demonstrate here two factors that have been found to modulate whole-cell recordings in malaria-infected RBCs. Firstly, negative holding potentials reduced inward currents (i.e. at negative potentials), although this result was highly complex. Secondly, the addition of human serum increased outward currents (i.e. at positive potentials) by approximately 4-fold and inward currents by approximately 2-fold. These two effects may help to resolve the conflicting data in the literature, although further investigation is required to understand the underlying mechanisms and their physiological relevance in detail.     

Inflammatory cytokine response to Vibrio vulnificus elicited by peripheral blood mononuclear cells from chronic alcohol users is associated with biomarkers of cellular oxidative stress

Vibrio vulnificus is the leading cause of death in the United States associated with the consumption of raw seafood, particularly oysters. In epidemiological studies, primary septicemia and inflammation-mediated septic shock caused by V. vulnificus is strongly associated with liver disease, often in the context of chronic alcohol abuse. The present study was undertaken to determine whether clinical biomarkers of liver function or cellular oxidative stress are associated with peripheral blood mononuclear cell inflammatory cytokine responses to V. vulnificus. Levels of interleukin-1 beta (IL-1 beta), IL-6, IL-8, and tumor necrosis factor alpha elicited in response to V. vulnificus and measured in cell supernatants were not associated with the liver biomarkers aspartate aminotransferase (AST) or alanine aminotransferase (ALT) or the AST/ALT ratio. In contrast, reduced glutathione (GSH) levels were associated with the release of all four cytokines (IL-1 beta [R(2) = 0.382; P = 0.006], IL-6 [R(2) = 0.393; P = 0.005], IL-8 [R(2) = 0.487; P = 0.001], and TNF-alpha [R(2) = 0.292; P = 0.021]). Those individuals with below-normal GSH levels produced significantly less proinflammatory cytokines in response to V. vulnificus. We hypothesize that persons with markers for cellular oxidative stress have increased susceptibility to V. vulnificus septicemia.     

Methods for optimal recovery of Malassezia furfur from blood culture.

Malassezia furfur, a recently described agent of catheter-associated sepsis, requires long-chained fatty acids for in vitro growth. To determine optimum conditions for recovery of the organism from blood culture, we compared a radiometric (BACTEC) with a lysis centrifugation-direct agar plating (Isolator) blood culture method. When blood culture isolates of M. furfur were suspended in phosphate-buffered saline and used as inocula, the BACTEC system detected the organisms radiometrically only when bottles were supplemented with lipid compounds; detection was often delayed (greater than or equal to 72 h) when small inoculum sizes were tested. The Isolator pediatric tube system detected growth of M. furfur within 48 h of plating onto a lipid-supplemented agar medium. Simulated blood culture experiments showed that the addition of whole human blood and Intralipid to the BACTEC 6B bottle was associated with rapid lysis of erythrocytes, accumulation of a chocolate brown sediment in the bottles, and fungicidal activity to the M. furfur isolates. In contrast, suspensions of M. furfur in whole human blood were stable for at least 8 h in Isolator tubes and quantitatively recoverable after plating onto agar. Of the two systems studied, the Isolator tube system provided a more suitable procedure for isolation of M. furfur from blood culture.     

In situ localization of pea enation mosaic virus double-stranded ribonucleic acid

Precursor ([³H]uridine) incorporation studies in the presence or absence of actinomycin D (AMD) showed that AMD-insensitive nucleic acid synthesis occurred only in the nuclei in pea enation mosaic virus (PEMV)-infected pea plant tissues. Ferritin-labeled antibody studies showed that ds-RNA was present only in nuclei. In vitro hybridization of the nucleic acid from various infected or healthy cell fractions with [¹²⁵I]PEMV-ss-RNA indicated that PEMV-ds-RNA was primarily associated with nuclei-enriched fractions from infected cells.An in situ hybridization technique, which utilized autoradiography to detect the subcellular location of material which hybridized with [¹²⁵I]PEMV-ss-RNA, was developed. This method confirmed that PEMV-ds-RNA was localized in the nuclei of PEMV-infected tissues.     

Expression of recombinant enterotoxigenic Escherichia coli colonization factor antigen I by Salmonella typhimurium elicits a biphasic T helper cell response

Protective immunity to enterotoxigenic Escherichia coli (ETEC) is antibody (Ab) dependent; however, oral immunization with purified ETEC fimbriae fails to elicit protective immunity as a consequence of antigenic alteration by the gastrointestinal (GI) tract. Unless unaltered ETEC fimbriae can reach the inductive lymphoid tissues of the GI tract, immunity to ETEC cannot be induced. To produce immunity, live vectors, such as Salmonella typhimurium, can effectively target passenger antigens to the inductive lymphoid tissues of the GI tract. By convention, oral immunizations with Salmonella vectors induce CD4(+) T helper (Th) cell responses by gamma interferon (IFN-gamma)-dominated pathways both to the vector and passenger antigen, resulting in serum immunoglobulin G2a (IgG2a) and modest mucosal IgA Ab responses. In the present study, mice orally immunized with a Salmonella vector engineered to stably express ETEC colonization factor antigen I (CFA/I) showed initially elevated serum IgG1 and mucosal IgA anti-CFA/I Ab responses. As expected, mice orally immunized with an E. coli-CFA/I construct elicited poor anti-CFA/I Ab responses. In fact, the addition of cholera toxin during oral E. coli-CFA/I immunization failed to greatly enhance mucosal IgA Ab responses. Seven days after immunization with the Salmonella-CFA/I construct, cytokine-specific ELISPOT showed induction of predominant Th2-type responses in both mucosal and systemic immune compartments supporting the early IgG1 and IgA anti-CFA/I Abs. By 4 weeks, the Th cell response became Th1 cell dominant from the earlier Th2-type responses, as evidenced by increased mucosal and systemic IFN-gamma-producing T cells and a concomitant elevation of serum IgG2a Ab responses. This biphasic response offers an alternative strategy for directing Salmonella vector-induced host immunity along a Th2 cell-dependent pathway, allowing for early promotion of mucosal and systemic Abs.     

Townes-Brocks syndrome

Townes-Brocks syndrome (TBS) is an autosomal dominant disorder with multiple malformations and variable expression. Major findings include external ear anomalies, hearing loss, preaxial polydactyly and triphalangeal thumbs, imperforate anus, and renal malformations. Most patients with Townes-Brocks syndrome have normal intelligence, although mental retardation has been noted in a few.     

Effect of drugs on vitamin B12 levels obtained using the Lactobacillus leichmanii method

In 750 consecutive assays of serum vitamin B₁₂ levels using Lactobacillus leichmanii, 25 (3·3%) showed inhibition. A satisfactory history of drug therapy was obtained in 23 cases. Seventeen of these were receiving ampicillin at the time. Two patients showed inhibition while receiving phenoxmethyl penicillin or phenethicillin. A prospective study of 11 patients detected inhibition in seven at varying intervals during ampicillin therapy. It was shown that the vitamin B₁₂ as measured by the radioisotope and Euglena gracilis methods was not affected. Inhibition of L. leichmanii was reproduced in vitro with concentrations of ampicillin corresponding to those obtained in therapy. Benzylpenicillin, streptomycin, and chloramphenicol had no such effect.     

Identification of a group 1-like capsular polysaccharide operon for Vibrio vulnificus

Virulence of Vibrio vulnificus correlates with changes in colony morphology that are indicative of a reversible phase variation for expression of capsular polysaccharide (CPS). Encapsulated variants are virulent with opaque colonies, whereas phase variants with reduced CPS expression are attenuated and are translucent. Using TnphoA mutagenesis, we identified a V. vulnificus CPS locus, which included an upstream ops element, a wza gene (wza(Vv)), and several open reading frames with homology to CPS biosynthetic genes. This genetic organization is characteristic of group 1 CPS operons. The wza gene product is required for transport of CPS to the cell surface in Escherichia coli. Polar transposon mutations in wza(Vv) eliminated expression of downstream biosynthetic genes, confirming operon structure. On the other hand, nonpolar inactivation of wza(Vv) was specific for CPS transport, did not alter CPS biosynthesis, and could be complemented in trans. Southern analysis of CPS phase variants revealed deletions or rearrangements at this locus. A survey of environmental isolates indicated a correlation between deletions in wza(Vv) and loss of virulent phenotype, suggesting a genetic mechanism for CPS phase variation. Full virulence in mice required surface expression of CPS and supported the essential role of capsule in the pathogenesis of V. vulnificus.