Genome sequence of a symbiotic cyanobacterium from the flowering plant Gunnera tinctoria.

Metagenomic analysis of the symbiotic cyanobacteria colonies within Gunnera tinctoria stems revealed a new strain of Nostoc. Here, we report its genome sequence.

Would Nesotriatoma bruneri Usinger, 1944 be a valid species?

Variation in the size and morphological differences intraspecific of Nesotriatoma flavida led to the description of N. bruneri. However, two years later the same author proposed the synonymization N. bruneri with N. flavida. N. bruneri was revalidated through morphological analysis after 35 years. Thus, given the existing taxonomic questioning between these Cuban triatomines, we analyzed new parameters such as genetic distance from the mitochondrial 16S rDNA deposited in Genbank and cytogenetic characterization, through the constitutive heterochromatin pattern, in order to reassess the specific status of N. bruneri. The analysis of the disposition of constitutive heterochromatin in the genome of these triatomines allowed observing that only the sex chromosome Y is heterochromatic, and the autosomes and the sex chromosomes X are euchromatic. These characteristics are identical to those described for N. flavida. By means of analysis of genetic distance matrix, we found that the genetic distance between N. bruneri and N. flavida was only 0.04%. Thus, by means of extremely low genetic distance and identical cytogenetic characteristics, we suggest that N. bruneri should be back again synonymized with N. flavida. However, we recommend that experimental hybrid crosses and new molecular analysis should be conducted, focusing mainly in the genetic distance based on other genes, on the rate of fertility of eggs and viability of hybrids to confirm the proposed of synonymization.

The suppression of human prostate tumor growth in mice by the intratumoral injection of a slow-release polymeric paste formulation of paclitaxel.

Most patients that present in the clinic with prostate cancer have either localized or recurrent postradiotherapy therapy tumors that may be amenable to injectable treatments using slow-release cytotoxic drugs. The objective of this preclinical study was to design an injectable polymeric paste formulation of paclitaxel for intratumoral injection into nonmetastatic human prostate tumors grown s.c. in mice. Paclitaxel was dissolved (10% w/w) in a blend of a biodegradable triblock copolymer of a random copolymer of D,L-lactide and epsilon-caprolactone (PLC) with poly(ethyleneglycol) [PEG; PLC-PEG-PLC] blended with methoxypoly(ethylene glycol) in a 40:60 ratio. Human prostate LNCaP tumors grown s.c. in castrated athymic male mice were injected with 100 microl of this paste at room temperature. Changes in tumor progression were assessed using both serum prostate-specific antigen (PSA) levels and tumor size. Paclitaxel inhibited LNCaP cell growth in vitro in a concentration-dependent fashion with an IC50 of 1 nM. Apoptosis was documented using DNA fragmentation analysis. The paste formulation solidified over a period of 1 h both in vivo and in aqueous media at 37 degrees C as the methoxypoly(ethylene glycol) component partitioned out of the insoluble PLC-PEG-PLC/paclitaxel matrix. The semisolid implant released drug at a rate of about 100 microg/day in vitro. In control mice treated with paste without paclitaxel, serum PSA levels increased from 2-8 ng/ml (mean, 4.3+/-2 ng/ml) to 60-292 ng/ml (mean, 181+/-88 ng/ml), and tumor volume increased from 30 to 1000 mm3. In mice treated with a single 100-microl injection 3 weeks after castration (early-phase treatment group), tumors decreased in volume from a mean of 43+/-19 mm3 to nonpalpable, and PSA levels decreased from a mean of 22+/-8 to 2+/-1 ng/ml by 8 weeks after castration. In mice treated 5 weeks after castration (androgen-independent tumors; late-phase treatment group), tumors decreased in volume from a mean of 233+/-136 mm3 to nonpalpable, and serum PSA decreased from 24+/-8 to 9+/-4 ng/ml. Observed side effects of the treatment were limited to minor ulceration at the needle injection site in paclitaxel-treated mice only. The controlled-release formulation can be injected via 22-gauge needles and is effective in inhibiting LNCaP tumor growth and PSA levels in mice bearing multiple nonmetastatic tumors. Paclitaxel may be an effective therapy for patients with localized tumors recurring after radiotherapy and for some patients with localized tumors who are not candidates for radical treatment.

Butyrate analogue, isobutyramide, inhibits tumor growth and time to androgen-independent progression in the human prostate LNCaP tumor model.

Progression to androgen independence remains the main obstacle to improving survival and quality of life in patients with advanced prostate cancer. Induction of differentiation may serve as a rational basis for prevention of progression to androgen independence by modulating gene expression activated by castration or upregulated during androgen-independent progression. The objectives of this study were to characterize the in vitro effects of sodium butyrate on human prostate cancer cell growth, PSA gene expression, and differentiation in the LNCaP tumor model and to determine whether tumor progression in vivo is delayed by isobutyramide, an orally bioavailable butyrate analogue with a longer half-life. The effects of isobutyramide on LNCaP tumor growth and serum PSA levels in both intact and castrate male mice were compared to controls. At concentrations >1 mM, butyrate induced dose-dependent changes towards a more differentiated phenotype, G1 cell cycle arrest, and an 80% decrease in LNCaP cell growth rates. PSA gene expression was increased threefold by butyrate, indicative of differentiation-enhanced gene expression. The half-life of isobutyramide in athymic mice was determined by gas chromatography to be 4 h. During a 4 week period in intact-placebo mice, tumor volume and serum PSA increased 4.1- and 6.6-fold, respectively, compared to twofold and 2.7-fold increases in tumor volume and serum PSA in intact-treated mice. During a 7 week period in castrate-placebo mice, tumor volume and serum PSA levels increased 2.4-fold and fourfold, respectively, compared to a 50% reduction in tumor volume and a twofold increase in serum PSA above nadir levels in castrate mice treated with adjuvant isobutyramide. Isobutyramide treatment induced pronounced morphological changes in LNCaP tumor cells, with loss of defined nucleoli and dispersion of chromatin distribution. LNCaP tumor PSA mRNA levels actually increased threefold, indicative of differentiation-enhanced gene expression. This study demonstrates that butyrate causes LNCaP cell cycle arrest and increased PSA gene expression, both indicative of differentiation. The combination of castration and adjuvant isobutyramide was synergistic in delaying tumor progression. Decreased tumor cell proliferation and increased PSA gene expression induced by isobutyramide results in disconcordant changes in serum PSA and tumor volume and reduces the utility of serum PSA as a marker of response to therapy.

Beta-funaltrexamine blockade of opioid-induced inhibition of somatostatin secretion from rat stomach.

Opioid peptides are potent inhibitors of gastric somatostatin secretion. In the current investigation the effect of mu-opioid receptor blockade on responses to [D-Ala2,N-Me-Phe4,Gly5-ol]enkephalin (DAGO) was studied. Gastric inhibitory polypeptide (GIP; 1 nM) -stimulated secretion of immunoreactive somatostatin was almost completely inhibited by DAGO (1 microM). The mu-receptor antagonists, beta-funaltrexamine and naloxonazine, blocked the effect of DAGO. Pretreatment of rats with beta-funaltrexamine, 24 h prior to perfusion, reduced the percentage inhibition by DAGO from 88.6 +/- 5.2% to 50.7 +/- 9.3%. These studies support the involvement of mu-opioid inhibitory receptors in the regulation of gastric somatostatin secretion.

Pharmacological characterization of rapidly accumulated adenosine by dissociated brain cells from adult rat.

Mechanically dissociated brain cells from adult rats were used to study biochemically and pharmacologically their capacity to accumulate rapidly [3H]adenosine. The assay, which used an inhibitor-stop method to prevent further uptake into cells, was characterized with respect to protein and optimal substrate concentrations, and incubation times that ranged from 5 to 180 s. The accumulation of [3H]adenosine using 15-s incubation periods, conditions under which less than 10% of accumulated [3H]adenosine was metabolized, was best described kinetically by a two-component system with Km and Vmax values for the high-affinity component of 0.8 microM and 6.2 pmol/mg protein/15 s and for the low-affinity component 259 microM and 2,217 pmol/mg protein/15 s, respectively. The potencies with which nucleosides, adenosine deaminase resistant adenosine receptor agonists, and nucleoside uptake inhibitors competed for these uptake components were determined. Of the nucleosides examined, adenosine was the "preferred" substrate for the uptake site. The Ki value of adenosine for the high-affinity component was 10.7 microM. Inosine and uridine competed for a single lower affinity uptake system: Ki values were 142 and 696 microM, respectively. Nucleoside uptake inhibitors--nitrobenzylthioinosine, dipyridamole, and dilazep--were the most potent inhibitors of [3H]adenosine accumulation tested: the Ki values for the high-affinity system were 0.11, 1.3, and 570 nM, respectively. The adenosine analogs S-phenylisopropyladenosine, R-phenylisopropyladenosine, and cyclohexyladenosine inhibited the high-affinity component with Ki values of 2.3, 9.3, and 14.5 microM, respectively. N-Ethylcarboxamidoadenosine competed for a single lower affinity uptake system: Ki, 292 microM.(ABSTRACT TRUNCATED AT 250 WORDS)