Intergeneric transfer of genes involved in the Rhizobium-legume symbiosis

Genes that seem to be involved in the initial steps of infection of a legume by Rhizobium have been transferred, by transformation, to mutant strains of Azotobacter vinelandii that are unable to fix nitrogen. These genes code for a surface antigen that binds specifically to a protein from the host plant.     

Specificity of amphetamine induced release of norepinephrine and serotonin from rat brain in vitro

Incubation of normal rat cortical or brain stem tissue with 3H-NE or 3H-5-HT and subsequent exposure to amphetamine produced a concentration-related release of the transmitters from tissue stores into the incubation media. Although pretreatment with the catecholamine neurotoxin in 6-hydroxydopamine (6-OHDA) reduced the retention of 3H-NE in both of these tissues, the proportion of 3H-NE released by amphetamine was attenuated only in cortical tissue. Pretreatment with the serotonergic neurotoxin, 5,6-dihydroxytryptamine (5,6-DHT) had no effect on the retention or release of 3H-NE in cortical or brain stem tissue. Pretreatment with 5,6-DHT reduced the retention of 3H-5-HT in the cortex and brain stem, but the release of 3H-5-HT was significantly attenuated only in the latter tissue. 6-OHDA pretreatment increased the retention and proportion of cortical 3H-5-HT released by amphetamine but reduced the release of brain stem 3H-5-HT in the absence of an effect on retention. It appears that the in vitro release of 3H-NE from the cerebral cortex occurs primarily from catecholamine and not serotonergic neurons whereas the cortical release of 3H-5-HT is not an event specific to serotonergic nerve terminals. The release of 3H-5-HT from brain stem does not appear to be restricted to the serotonergic cell bodies since its release was attenuated by 5,6-DHT and 6-OHDA.     

Serial pulmonary function tests in the diagnosis of P. carinii pneumonia

The predictive value of serial versus isolated measurements of transfer factor for carbon monoxide (TLCO) in the diagnosis of pneumocystis carinii pneumonia (PCP) in a cohort of 474 HIV-1 seropositive patients, with all stages of HIV disease, was evaluated. Two groups of patients were studied, one group with serial lung function measurements (Group 1) and another with only a single set of measurements (Group 2). During the study period 118 patients performing serial tests developed a respiratory illness of which 58 were performing monthly and 60 three monthly measurements of lung function (Group 1). In 36 patients from Group 1, where PCP was diagnosed, monthly lung function tests showed a decrease in TLCO from 68% (+/- 3.2) (SEM), (8 weeks prior to illness), to 44% (+/- 2.5) predicted normal at presentation, whereas in 22 patients who did not have PCP, TLCO fell from 71% (+/- 4.5) to 57% (+/- 3.1). TLCO was thus reduced to lower values in these with PCP than in those without PCP (p < 0.05). A fall of TLCO of 5% from initial values when used as predictive for presence of PCP had a sensitivity of 75% and a specificty of 28% (positive predictive value 56%; negative predictive value 48%). TLCO was < 70% predicted in 72/78 patients with PCP who performed only single lung function tests (Group 2), which gave a sensitivity of 92% and a specificity of 71% as a diagnostic test for PCP when compared with the cohort as a whole. The positive predictive value was 34%, negative predictive value was 98%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Neither intestinal sequestration of bile acids nor common bile duct ligation modulate the expression and function of the rat ileal bile acid transporter

The regulatory responses of bile acid (BA) transport in the terminal ileum to perturbations in BA homeostasis are complex, and conflicting results have been reported by different investigators. These studies were designed to examine the response of this system to a reduction in ileal bile salt concentrations at both a functional and molecular level. Common bile duct ligation (BDL) or feeding of a novel bile acid-binding compound, GT31-104HB, for 7 days were used to reduce ileal apical membrane bile salt flux. Apical bile acid transport function was assessed by examining sodium-dependent uptake of [3H]-taurocholate (TC) into brush border membrane vesicles (BBMV). Expression of the apical sodium-dependent bile acid transporter (ASBT) and the ileal lipid-binding protein (ILBP) were assessed by Western blotting with quantitation using [125I]-labeled secondary antibody and a phosphorimager. Neither common BDL nor intestinal sequestration of BA led to a change in ileal bile acid transport function or the expression of the ASBT or the ILBP. These results indicate that a reduction in presentation of bile salts to the apical surface of the terminal ileum does not modulate the expression of the genes involved in their transport.