Enantioselective determination of metoprolol acidic metabolite in plasma and urine using liquid chromatography chiral columns: applications to pharmacokinetics

Enantioselective separations on chiral stationary phases with or without derivatization were developed and compared for the HPLC analysis of (+)-(R)- and (-)-(S)-metoprolol acidic metabolite in human plasma and urine. The enantiomers were analysed in plasma and urine without derivatization on a Chiralcel OD-R column, and in urine after derivatization using methanol in acidic medium on a Chiralcel OD-H column. The quantitation limits were 17 ng of each enantiomer/ml plasma and 0.5 microgram of each enantiomer/ml urine using both methods. The confident limits show that the methods are compatible with pharmacokinetic investigations of the enantioselective metabolism of metoprolol. The methods were employed in a metabolism study of racemic metoprolol administered to a patient phenotyped as an extensive metabolizer of debrisoquine. The enantiomeric ratio (+)-(R)/(-)-(S)-acid metabolite was 1.1 for plasma and 1.2 for urine. Clearances were 0.41 and 0.25 l/h/kg, respectively, for the (+)-(R)- and (-)-(S)-enantiomers. The correlation coefficients between the urine concentrations of the acid metabolite enantiomers obtained by the two methods were >0.99. The two methods demonstrated interchangeable application to pharmacokinetics.     

Multiparametric magnetic resonance imaging-guided salvage radiotherapy in prostate cancer

AimTo analyse the efficacy and toxicity of postprostatectomy SRT in patients with a BCR evaluated with mpMRI.BackgroundMultiparametric magnetic resonance imaging (mpMRI) has the ability to detect the site of pelvic recurrence in patients with biochemical recurrence (BCR) after radical prostatectomy (RP). However, we do not know the oncological outcomes of mpMRI-guided savage radiotherapy (SRT).ResultsLocal, lymph node, and pelvic bone recurrence was observed in 13, 4 and 2 patients, respectively. PSA levels were significantly lower in patients with negative mpMRI (0.4 ng/mL [0.4]) vs. positive mpMRI (2.2 ng/mL [4.1], p = 0.003). Median planning target volume doses in patients with visible vs. non-visible recurrences were 76 Gy vs. 70 Gy. Overall, mean follow-up was 41 months (6–81). Biochemical relapse-free survival (bRFS) at 3 years was 82.3% and 82.5%, respectively, for the negative and positive mpMRI groups (p = 0.800). Three-year rates of late grade ≥2 urinary and rectal toxicity were 14.8% and 1.9%, respectively; all but one patient recovered without sequelae.ConclusionSRT to the macroscopic recurrence identified by mpMRI is a feasible and well-tolerated option. In this study, there were no differences in bRFS between MRI-positive and MRI-negative patients, indicating effective targeting of MRI-positive lesions.     

Seasonal transmission of Leishmania (Leishmania) mexicana in the state of Campeche, Yucatan Peninsula, Mexico

In the Yucatan Peninsula, Mexico, localized cutaneous leishmaniasis (LCL) caused by Leishmania (Leishmania) mexicana is a typical wild zoonosis restricted to the forest, and humans are only accidentally involved. The transmission of L. (L.) mexicana has been related to the patient's occupation: "chicleros" (gum collectors) and agricultural workers. The objective of this study was to document L. (L.) mexicana seasonally of transmission in endemic areas of LCL in the state of Campeche, Yucatan Peninsula, Mexico. The timing of incidence of LCL in humans during 1993-1994, as well as the rate and time of infection in rodents and sand flies between February 1993 and March 1995 were analyzed. Rodents and sand flies were found infected between November and March, when men carried out their field activities and are exposed. Based on results analyzed, it is concluded that L. (L.) mexicana in the endemic area of LCL in the state of Campeche, Yucatan Peninsula, Mexico, presents a seasonal transmission restricted to the months of November to March. The knowledge of the timing of the transmission cycle in an endemic area of leishmaniasis is very important because intervention measures on the high-risk focus and population might be restricted.     

The effect of light levels on daily patterns of chlorophyll fluorescence and organic acid accumulation in the tropical CAM treeClusia hilariana

Sandy plains are characteristic of the coastal region of Brazil. We investigated the diel patterns of changes in organic acid levels, leaf conductance and chlorophylla fluorescence for sun-exposed and shaded plants ofClusia hilariana, one of the dominant woody species in the sandy coastal plains of northern Rio de Janeiro state. Both exposed and shaded plants showed a typical CAM pattern with considerable diel oscillations in organic acid levels. The degradation of both malic and citric acids during the midday stomatal closure period could lead to potential CO₂ fixation rates of 28 mol m^-2 s^-1 in exposed leaves. Moreover, exposed leaves exhibited large increases in total non-photochemical quenching (q_N) accompanied by a substantial decrease in effective quantum yield during the course of the day. However, these potential high rates of CO₂ fixation and the increases inqn of exposed plants were not enough to maintain the primary electron acceptor of photosystem II (q_A) in a low reduction state, similar to that of shaded plants. As a result, there was a moderate increase in the reduction state of q_A throughout the day. Most of the decline in photochemical efficiency of exposed leaves ofC. hilariana was reversible, as evidenced by the high levels of pre-dawn potential quantum yields (F_v/F_m) and their rapid recovery after sunset. However, the depletion of the organic acid pool in the afternoon resulted in an accentuated subsequent drop in F_v/F_m, suggesting that prolonged periods of water stress accompanied by high irradiance levels may expose plants ofC. hilariana in unprotected habitats to the danger of photoinhibition.     

Emergence of nosocomial Mycobacterium massiliense infection in Goiás, Brazil

A cluster of surgical site infection cases after arthroscopic and laparoscopic procedures occurred between 2005 and 2007 in Goiania, in the central region of Brazil. Nontuberculous mycobacteria (NTM) were isolated from samples (exudates from cutaneous abscesses) from 18 patients of seven private hospitals. There were no reports of post-surgical arthroscopic and laparoscopic mycobacterial infections in Goiania apart from this period. The 18 isolates were identified as Mycobacterium massiliense by PCR-restriction digestion of the hsp65 gene, pulsed-field gel electrophoresis (PFGE) comparisons, and rpoB partial gene sequencing. All isolates were typed as a single clone, indicating that they have the same origin, which suggests a common source of infection for all patients.     

Comparison of vitrification and slow cooling for umbilical tissues

The tissue cryopreservation maintains the cellular metabolism in a quiescence state and makes the conservation possible for an indefinite period of time. The choice of an appropriate cryopreservation protocol is essential for maintenance of cryopreserved tissue banks. This study evaluated 10 samples of umbilical cord, from which small fragments of tissue (Wharton’s jelly and cord lining membrane) were subjected to two protocols of cryopreservation: slow cooling and vitrification. The samples were frozen for a period of time ranging from 5 to 78 days. The efficiency of cryopreservation was evaluated by testing cell viability, histological analysis, cell culture, cytogenetic analysis and comparison with the results of the fresh samples. The results showed that the slow cooling protocol was more efficient than the vitrification for cryopreservation of umbilical cord tissue, because it has caused fewer changes in the structure of tissue (edema and degeneration of the epithelium) and, despite the significant decrease cell viability compared to fresh samples, the ability of cell proliferation in vitro was preserved in most samples. In conclusion, this study showed that it is possible to cryopreserve small fragments of tissue from the umbilical cord and, to obtain viable cells capable of proliferation in vitro after thawing, contributing to the creation of a frozen tissue bank.     

Seasonal metabolic changes in a year-round reproductively active subtropical tree-frog (Hypsiboas prasinus)

Although seasonal metabolic variation in ectothermic tetrapods has been investigated primarily in the context of species showing some level of metabolic depression during winter, but several species of anurans maintain their activity patterns throughout the year in tropical and subtropical areas. The tree-frog Hypsiboas prasinus occurs in the subtropical Atlantic Forest and remains reproductively active during winter, at temperatures below 10 degrees C. We compared males calling in summer and winter, and found that males of H. prasinus exhibit seasonal adjustments in metabolic and morphometric variables. Individuals calling during winter were larger and showed higher resting metabolic rates than those calling during summer. Calling rates were not affected by season. Winter animals showed lower liver and heart activity level of citrate synthase (CS), partially compensated by larger liver mass. Winter individuals also showed higher activity of pyruvate kinase (PK) and lower activity of CS in trunk muscles, and higher activity of CS in leg muscles. Winter metabolic adjustments seem to be achieved by both compensatory mechanisms to the lower environmental temperature and a seasonally oriented aerobic depression of several organs. The impact of seasonal metabolic changes on calling performance and the capacity of subtropical anurans for metabolic thermal acclimatization are also discussed.     

The genomic composition of Tricepiro, a synthetic forage crop.

Chromosome in situ hybridization (FISH and GISH) is a powerful tool for determining the chromosomal location of specific sequences and for analysing genome organization and evolution. Tricepiro (2n = 6x = 42) is a synthetic cereal obtained by G. Covas in Argentina (1972), which crosses hexaploid triticale (2n = 6x = 42) and octoploid Trigopiro (2n = 8x = 56). Several years of breeding produced a forage crop with valuable characteristics from Secale, Triticum, and Thinopyrum. The aim of this work is to analyse the real genomic constitution of this important synthetic crop. In situ hybridization using total DNA of Secale, Triticum, and Thinopyrum as a probe (GISH) labelled with biotin and (or) digoxigenin showed that tricepiro is composed of 14 rye chromosomes and 28 wheat chromosomes. Small zones of introgression of Thinopyrum on wheat chromosomes were detected. The FISH using the rye repetitive DNA probe pSc 119.2 labelled with biotin let us characterize the seven pairs of rye chromosomes. Moreover, several wheat chromosomes belonging to A and B genomes were distinguished. Therefore, tricepiro is a synthetic hexaploid (2n = 6x = 42) being AABBRR in its genomic composition, with zones of introgression of Thinopyrum in the A genome of wheat.     

Molecular identification and dynamics of microbial communities in reactor treating organic household waste

The prokaryotic diversity associated with organic household waste (OHW), leachate (start-up inoculum), and mesophilic anaerobic digestion processes in the degradation of OHW for 44 and 90 days was investigated using a culture-independent approach. Bacterial and archaeal 16S rRNA and mcrA gene clone libraries were constructed from community DNA preparations. Bacterial clones were affiliated with 13 phyla, of which Firmicutes, Proteobacteria, and Bacteroidetes were represented in all libraries, whereas Actinobacteria, Thermotogae, Lentisphaerae, Acidobacteria, Chloroflexi, Cyanobacteria, Synergistetes, Spirochaetes, Deferribacteres, and Deinococcus-Thermus were exclusively identified in a single library. Within the Archaea domain, the Euryarchaeota phylum was the only one represented. Corresponding sequences were associated with the following orders of hydrogenotrophic methanogens: Methanomicrobiales (Methanoculleus genus) and Methanobacteriales (Methanosphaera and Methanobacterium genera). One archaeal clone was not affiliated with any order and may represent a novel taxon. Diversity indices showed greater diversity of Bacteria when compared to methanogenic Archaea.