Species delineation and clonal diversity in four Bifidobacterium species as revealed by multilocus sequencing

The genus Bifidobacterium comprises several species that are important contributors to the gut microbiome, with some strains having beneficial health effects. Understanding the evolutionary emergence of advantageous biological properties requires knowledge of the genetic diversity and clonal structure of species. We sequenced seven housekeeping genes in 119 Bifidobacterium strains of Bifidobacterium animalis, Bifidobacterium bifidum, Bifidobacterium breve and Bifidobacterium longum. Phylogenetic analysis of concatenated sequences delineated sequence clusters that correspond to previously named taxa, and suggested that B. longum subsp. infantis is a nascent lineage emerging from within B. longum subsp. longum. Clear traces of recombination among distant bifidobacterial species indicate leaky species borders and warn against the practice of single gene-based identification. Multilocus sequence typing achieved precise strain genotyping, with discrimination indices above 99% in B. bifidum, B. breve and B. longum, providing a powerful tool for strain traceability, colonization dynamics and ecological studies. Frequent homologous recombination accelerates clonal diversification and may facilitate the transfer of biological properties among bifidobacterial strains.     

New molecular marker for Trypanosoma (Duttonella) vivax identification.

Trypanosoma vivax is a widespread hemoparasite in tropical areas and is pathogenic to ruminant domestic livestock as well as wild ruminants. The accurate identification of parasites in both hosts and vectors is crucial for epidemiological studies and disease control programs. We describe here the development of molecular markers specific for T. vivax identification. These markers were used to identify mouthpart infections in field-collected tsetse flies from Cameroon. The markers target the genomic sequence of a species-specific antigen from the bloodstream stages. No cross amplification with other trypanosome species was observed, which makes the markers a reliable tool to detect T. vivax infections, both in hosts and vectors. The PCR-amplified sequence contains a (CA)_n microsatellite repeat for which 11 different alleles were identified. This microsatellite, which showed high polymorphism, provides a suitable marker for population genetic studies.     

ErbB-4 and neuregulin expression in the adult mouse olfactory bulb after peripheral denervation

ErbB-4 is expressed by the periglomerular and the mitral/tufted cells of the adult mouse olfactory bulb (OB) and in the present work we tested whether this expression is regulated by the olfactory nerve input to the OB. Reversible zinc sulphate lesions of the olfactory mucosa were made in adult mice and the deafferented OB analysed by immunohistochemistry, Western blotting and semiquantitative RT-PCR. Following deafferentation, the expression of erbB-4, erbB-2 and neuregulin-1 (NRG-1) mRNAs in the OB was altered. At early stages (7-14 days) after lesion the levels of expression of olfactory marker protein (OMP), tyrosine hydroxylase (TH), erbB-4 and NRG-1 mRNAs were decreased, whilst expression of erbB-2 increased and that of NRG-2 was not significantly altered. We observed at least two distinct time courses for these expression changes. The lowest amounts of mRNA for erbB-4 and NRG-1 were observed at day 7 after lesion, whilst mRNAs for TH and OMP were lowest at day 14. At day 28 after the lesion, when olfactory receptor neuron axons had reinnervated the olfactory bulb, the expression levels of OMP, TH, erbB-2, erbB-4 and NRG-1 were identical to control values. These results indicate that the expression of erbB-4 mRNA and protein in periglomerular and mitral cells is controlled by peripheral olfactory innervation. The tight correlation in NRG-1 and erbB-4 expression levels also suggests a possible functional link that deserves further exploration.     

Combined effects of fasting and alanine on liver function recovery after cold ischemia

The effect of donor nutritional status on hepatic function recovery after cold ischemia is still debated. We demonstrated previously that a 48-h fast diminished the survival rate of liver-transplanted rats and that the deleterious effect of fasting was prevented by infusion of alanine to the recipient at reperfusion. Whether the duration of fasting influenced the protective effect of alanine and whether this effect was metabolic were not known, and the elucidation of these questions is the aim of this study. The effect on hepatic function recovery of fasting periods of 24 h, 48 h and 72 h prior to cold ischemia were studied in a model of isolated, perfused rat liver. After a cold-ischemic time of 24 h in University of Wisconsin (UW) solution at 4 degrees C, livers were reperfused for 3 h. The combined effect of alanine (8 mM) infusion at liver reperfusion was evaluated for each prior fasting period. The addition of pyruvate (8 mM), a metabolic intermediary of alanine, was only tested in the 72-h fasting group. The evaluation criteria were: liver weight after reperfusion, release of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) in the perfusate, bile production, vascular resistance and liver histology after reperfusion. The enzyme release at reperfusion was significantly higher when livers were harvested from rats submitted to a 48-h fast (ALT) or a 72-h fast (ALT, AST, LDH), as compared to those from fed rats. Vascular resistance was increased in 72-h fasted livers. An addition of alanine (8 mM) at reperfusion lowered the release of AST, ALT and LDH. This effect was more obvious when the fasting duration was increased. By contrast, the addition of pyruvate at reperfusion did not improve the recovery of livers submitted to a 72-h fasting period before preservation. A long fasting period is deleterious as compared to feeding; however, this effect can be compensated by infusion of alanine at reperfusion. The mechanism involved is not metabolic. In a clinical setting, the infusion of alanine to the recipient at reperfusion may be a convenient way to compensate for donor undernutrition, especially after a long stay in an intensive care unit.     

Drug-metabolizing enzyme activities in the liver and intestine of rats exposed to DDT: effects of vitamin A status

One-half of a group (deficient group) of male Wistar rats which received a daily intake of 50 IU of vitamin A/kg of body weight, and one-half of a second group (normal group), which received 500 IU of the same substance, were treated by intragastric intubation with 40 mg of DDT/day/kg body weight. Rats were killed after 5 or 12 days of exposure to DDT. The liver vitamin A contents indicated a different rate of storage depending on the amount of vitamin A. DDT increased the relative liver weight and decreased hepatic vitamin A storage in both groups; it induced benzo(a)pyrene hydroxylase (AHH) and glutathione-S-transferase (GST) activities in both organs and cytochrome P 450 only in the liver. At both ages, no change was noted in the cytochrome P450 content in the liver and intestine, whereas enzymatic activities, unchanged in the liver, were significantly modified in the intestine and included a reduction in AHH activity, an increase in UDP-glucuronosyl transferase (UDPGT) and GST activities. Vitamin A deficiency had no effect on AHH and UDPGT activities nor on the cytochrome P 450 content in the liver or intestine. However, it significantly increased the GST activity in the intestine, but not in the liver.     

Altered interpretation of neck proprioceptive signals in persons with subclinical recurrent neck pain.

OBJECTIVE: To evaluate whether subjects with subclinical recurrent neck pain have an altered interpretation of neck proprioceptive signals. DESIGN: A comparative group design. SUBJECTS: Twelve subjects with recurrent neck pain and 12 control subjects. METHODS: The shoulder, head, trunk and whole-body position were measured under the following conditions: active and passive elevation and depression of the right shoulder and vibration of the trapezius muscle. RESULTS: During passive shoulder movements both groups moved their head in the opposite direction (p<0.05). During passive elevation subjects with recurrent neck pain showed a significant over-appraisal of shoulder position. Both groups responded similarly to active movements. Subjects with recurrent neck pain and control subjects showed similar trunk and head-to-trunk movements during shoulder movements. Subjects with recurrent neck pain, however, made larger movements compared with healthy subjects (p<0.05). During trapezius muscle vibration similar whole-body movements were found in both groups. CONCLUSION: These results show a modified interpretation of neck proprioceptive signals in subjects with recurrent neck pain and may reflect an offset in the egocentric reference frame or a decreased capacity to switch between reference frames. Better insight into these mechanisms might lead to better evaluation and treatment of subjects with recurrent neck pain and to a reduction in recurrent episodes.     

Local Anesthetic Inhibition of m1 Muscarinic Acetylcholine Signaling

Background: Local anesthetics inhibit lipid mediator signaling (lysophosphatidate, thromboxane) by acting on intracellular domains of the receptor or on the G protein. On receptors for polar agonists, the ligand-binding pocket could form an additional site of interaction, possibly resulting in superadditive inhibition. The authors therefore investigated the effects of local anesthetics on m1 muscarinic receptor functioning.

Methods: The authors expressed receptors in isolation using Xenopus oocytes. Using a two-electrode voltage clamp, the authors measured the effects of lidocaine, QX314 (permanently charged), and benzocaine (permanently uncharged) on Ca2+-activated Cl- currents elicited by methylcholine. The authors also characterized the interaction of lidocaine with [3H] quinuclydinyl benzylate ([3H]QNB) binding to m1 receptors.

Results: Lidocaine inhibited muscarinic signaling with a half-maximal inhibitory concentration (IC50 18 nm) 140-fold less than that of extracellularly administered QX314 (IC50 2.4 [mu]m). Intracellularly injected QX314 (IC50 0.96 mm) and extracellularly applied benzocaine (IC50 1.2 mm) inhibited at high concentrations only. Inhibition of muscarinic signaling by extracellularly applied QX314 and lidocaine was the result of noncompetitive antagonism. Intracellularly injected QX314 and benzocaine inhibited muscarinic and lysophosphatidate signaling at similar concentrations, suggesting an action on the common G-protein pathway. Combined administration of intracellularly injected (IC50 19 [mu]m) and extracellularly applied QX314 (IC50 49 nm) exerted superadditive inhibition. Lidocaine did not displace specific [3H]QNB binding to m1 receptors.     

Treatment of bone metastases of prostate cancer with strontium-89 chloride: efficacy in relation to the degree of bone involvement

This retrospective study evaluated the toxicity and efficacy of strontium-89 chloride (Metastron, Amersham) in 94 patients with painful bone metastases of prostate cancer (117 injections of 150 MBq) and compared the efficacy of treatment in patients with moderate and extensive bone involvement. The predictive value of flare response with regard to analgesic response was also studied. High-grade leukothrombopenias were observed after only 5% of injections. An improvement in quality of life was obtained in 65% of cases, a decrease in pain in 78% (31% complete response) and a reduction of analgesics in 60%. Efficacy was significantly better for pain decrease (P=0.005) and reduction of analgesics (P=0.018), and response was significantly longer (P<0.0035) in patients with moderate than in patients with extensive bone involvement. The flare response observed in 23% of cases was not predictive of pain response (P=0.919) or reduction of analgesics (P=0.353). A second dose prolonged analgesia in three-quarters of cases without any apparent increase in toxicity. These results confirm the benefit of ⁸⁹Sr chloride for the treatment of metastatic bone pain and suggest that internal radiotherapy should be started earlier. A bone scan could be proposed at the time of hormonal escape resulting in bone pain, and internal radiotherapy could be initiated when several metastatic foci exist, even if only one is painful. In this way, pain-free follow-up could be prolonged, and the transition to other therapeutic approaches, particularly opioids, delayed.