Genetic structuring in a Neotropical palm analyzed through an Andean orogenesis-scenario

Andean orogenesis has driven the development of very high plant diversity in the Neotropics through its impact on landscape evolution and climate. The analysis of the intraspecific patterns of genetic structure in plants would permit inferring the effects of Andean uplift on the evolution and diversification of Neotropical flora. In this study, using microsatellite markers and Bayesian clustering analyses, we report the presence of four genetic clusters for the palm Oenocarpus bataua var. bataua which are located within four biogeographic regions in northwestern South America: (a) Chocó rain forest, (b) Amotape-Huancabamba Zone, (c) northwestern Amazonian rain forest, and (d) southwestern Amazonian rain forest. We hypothesize that these clusters developed following three genetic diversification events mainly promoted by Andean orogenic events. Additionally, the distinct current climate dynamics among northwestern and southwestern Amazonia may maintain the genetic diversification detected in the western Amazon basin. Genetic exchange was identified between the clusters, including across the Andes region, discarding the possibility of any cluster to diversify as a distinct intraspecific variety. We identified a hot spot of genetic diversity in the northern Peruvian Amazon around the locality of Iquitos. We also detected a decrease in diversity with distance from this area in westward and southward direction within the Amazon basin and the eastern Andean foothills. Additionally, we confirmed the existence and divergence of O. bataua var. bataua from var. oligocarpus in northern South America, possibly expanding the distributional range of the latter variety beyond eastern Venezuela, to the central and eastern Andean cordilleras of Colombia. Based on our results, we suggest that Andean orogenesis is the main driver of genetic structuring and diversification in O. bataua within northwestern South America.

[Usefulness of procalcitonin upon admission to intensive care in the diagnosis and prognosis of sepsis]

OBJECTIVE

To assess the usefulness of procalcitonin (PCT) upon admission to the Intensive Care Unit (ICU) in the diagnosis and prognosis of sepsis

DESIGN

A 12-month prospective observational cohort study was carried out

SETTING

An 11-bed polyvalent ICU Belonging to a University hospital

PATIENTS

Fifty patients with systemic inflammatory response syndrome (SIRS) were included. The mean age of the patients was 51.66 years, and 68% of them were males

VARIABLES OF INTEREST

Upon admission, the concentration of PCT and C-reactive protein (CRP) was assessed. At discharge, the final diagnosis and outcome were reviewed

RESULTS

Thirty-six patients had sepsis. Mean PCT ± SD was higher in sepsis than in non-infectious SIRS (19.3 ± 4.9 vs. 0.65 ± 0.2) ng/ml) (P=.001). PCT had greater discriminating power than CRP (AUC 0.932 vs. 0.827). The cut-off value of PCT for the diagnosis of sepsis was 0.92 ng/dl, with a sensitivity of 80.56%, specificity 85.71%, positive predictive value 93.55% and negative predictive value 63.16%, LR+ 5.64 and LR- 0.23. Mortality was higher in patients with sepsis (52.78% vs. 21.43%) (P=.039). Mean PCT ± SD upon admission among survivors and deceased patients with sepsis was 18.7 ± 6.7 and 19.5 ± 7.5 ng/ml, respectively (P=.934).

CONCLUSIONS

PCT upon admission to the ICU is useful for the diagnosis of sepsis, and is more effective than PCR in this respect. However, it is of no help in estimating the short-term prognosis.

MRI and endoscopic ultrasonography in the staging of gastric cancer

OBJECTIVE

to determine the diagnostic precision of endoscopic ultrasounds (EUS) and magnetic resonance imaging (MRI) in the preoperative staging of gastric cancer.

METHODS

a prospective, blind study was carried out in 17 patients diagnosed with gastric cancer (GC) using endoscopic biopsy from November 2002 to June 2003. Patients underwent preoperative MRI and EUS. The reference test used was pathology, and laparotomy for non-resectable cases.

RESULTS

MRI (53%) was better than EUS in the assessment of gastric wall infiltration (35%). MRI (50%) was also superior to EUS (42%) for N staging. After pooling stages T1-T2 and T3-T4 together, results improved for both MRI (67 and 87.5%, respectively) and EUS (67 and 62.5%, respectively) (p < 0.05). N staging--lymph node invasion--results were correct in 50% for MRI as compared to EUS (42%). In classifying positive and negative lymph nodes EUS was superior to MRI (73 versus 54%).

CONCLUSIONS

MRI was the best method in the assessment of gastric wall infiltration. EUS was superior to MRI for T1 staging, and in the assessment of lymph node infiltration.

Platelet-activating factor modulates microvascular dynamics through phospholipase C in the hamster cheek pouch

We studied the interactions between platelet-activating factor (PAF) and phospholipase C (PLC) in the modulation of microvascular responses in the hamster cheek pouch using intravital microscopy and computer-assisted image analysis. Changes in arteriolar diameter and in integrated optical intensity (IOI, an index of vascular permeability) were measured. Fluorescein-isothiocyanate-labeled dextran 150 (FITC-Dx 150) served as a tracer for macromolecular transport. 2-Nitro-4-carboxyphenyl N,N-diphenylcarbamate (NCDC) and 1-(6-((17beta-3-methoxyestra-1,3, 5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5,-dione (U-73122), two PLC inhibitors, were applied topically in separate experiments. PAF at 10(-7) M elevated IOI from baseline to a mean +/- SEM value of 70. 7 +/- 8.9 units. Pretreatment with 10(-4) and 10(-5) M NCDC and with U-73122 at 10(-5) and 10(-6) M attenuated the maximal increment in mean IOI (+/-SEM) induced by PAF at 10(-7) M to mean +/- SEM values of 30.6 +/- 6.5, 39.3 +/- 6.0, 12.1 +/- 4.8, and 41.5 +/- 6.0, respectively. The simultaneous vasoconstrictor action of 10(-7) M PAF was expressed as the experimental-to-baseline ratio, with the baseline diameter adjusted to a value of 1. PAF constricted the arterioles to a mean +/- SEM ratio of 0.30 +/- 0.07. Pretreatment with the PLC inhibitors NCDC at 10(-4) and 10(-5) M NCDC and with U-73122 at 10(-5) and 10(-6) M attenuated 10(-7) M PAF-induced vasoconstriction to mean +/- SEM diameter ratios of 0.55 +/- 0.05, 0. 48 +/- 0.06, 0.55 +/- 0.08, and 0.58 +/- 0.06, respectively. Our results demonstrate that PLC is an element of the biochemical pathway involved in PAF modulation of microvascular permeability and in PAF modulation of arteriolar diameter.

[Ampicillin resistance mediated by the R plasmid in strains of Shigella flexneri]

Forty Shigella flexneri strains isolated from children attended to at the Children's Hospital of Camagüey during an outbreak of acute diarrheal disease were studied; the minimal inhibitory concentration of ampicillin was determined. 33 strains (82.5%) were resistant to higher concentrations: 8 to 16 micrograms/mL, and 7 were susceptible to 4 micrograms/mL concentrations. Resistance plasmid (R) extraction was carried out in all the isolated strains and a common plasmid was found this plasmid was purified and transferred to Escherichia coli HE 101. Resistance transmission was tested.

Protein kinase C modulates microvascular permeability through nitric oxide synthase

Protein kinase C (PKC) serves important functions in signal transduction. We hypothesized that PKC modulation of microvascular permeability to macromolecules is mediated by nitric oxide (NO). To test this hypothesis, we stimulated PKC topically with 10(-7) M phorbol 12,13-dibutyrate (PDBu) in the hamster check pouch microcirculation. NG-monomethyl-L-arginine (L-NMMA) at 10(-4) M was superfused in a bicarbonate buffer solution throughout the experiment to inhibit the activity of NO synthase. We evaluated changes in transport of fluorescein isothiocyanate-labeled 150,000 mol wt dextran by integrated optical intensity (IOI) using intravital fluorometry and computer-assisted digital image analysis. Postcapillary areas were recorded. PDBu increased IOI from baseline to a value of 46.8 +/- 6.3 units (+/- SE). Pretreatment with L-NMMA decreased the PDBu-stimulated increment to 10.8 +/- 0.9 units. These results demonstrate that PKC-activated modulation of macromolecular transport operates through a mechanism involving the production of NO.

Platelet activating factor modulates microvascular permeability through nitric oxide synthesis

Biochemical signaling determines the specific action of vasomediators in the control of microvascular permeability and tone. We tested the hypothesis that nitric oxide (NO) synthesis is involved in the biochemical signaling pathway of platelet activating factor (PAF). The cheek pouch of anesthetized male Syrian hamsters was used as a microvascular model. Vessel diameter [expressed as the ratio of the experimental to the control (e/c) diameter, with control diameter normalized to 1] and extravasation of FITC-dextran 150 by integrated optical intensity (IOI) were determined using intravital fluorescent microscopy and computer-assisted digital image analysis. N-Nitro-L-arginine methyl ester (L-NAME) at 10(-5) and 10(-6) M and N-nitro-L-mono-methyl arginine (L-NMMA) at 10(-4) and 10(-5) M were used as inhibitors of NO synthase (NOS). Acetylcholine (ACh) and bradykinin were used as indirect indices of NOS activation. L-NAME and L-NMMA attenuated both ACh and bradykinin vasodilatory effects as well as the bradykinin-induced increase in vascular permeability. Topical PAF (10(-7) M) caused vasoconstriction (mean +/- SEM e/c ratio = 0.3 +/- 0.1) and increased IOI from a normalized baseline of 0 to 67.4 +/- 12.8. Topical administration of L-NAME produced differential effects on the series-arranged arterioles but had no effect on postcapillary venular permeability. L-NMMA did not influence the basal arteriolar diameter, but at 10(-5) M it caused a small increase in permeability (IOI = 14.3 +/- 4.2). In the presence of NOS inhibitors, PAF caused a reduced arteriolar constriction (e/c ratio = 0.6 +/- 0.1) relative to PAF alone. Both NOS inhibitors reduced the PAF-stimulated increase in vasopermeability. At 10(-5) M L-NMMA, the PAF-stimulated IOI mean value was 26.1 +/- 5.2, while at 10(-4) M L-NMMA the PAF-stimulated IOI was 15.2 +/- 2.6 compared to 10(-7) M PAF (67.4 +/- 12.8). These results support our hypothesis that NO synthesis is a step in the biochemical signaling pathway of the postcapillary cellular responses to PAF.

Polyarginine and eosinophil-derived major basic protein increase microvascular permeability independently of histamine or nitric oxide release

We tested the hypothesis that cationic peptides (polyarginine; poly-argn) and eosinophil-derived major basic protein (MaBP) increase permeability by stimulating the release of histamine and/or nitric oxide. We used intravital microscopy, clearance, and integrated optical intensity (IOI), using FITC-dextran 150 (FITC-dx 150) as a tracer, to evaluate changes in microvascular permeability in the hamster cheek pouch. Poly-argn at 1 microM (topical) increased the clearance of FITC-dx 150 from 610 to 3240 nl/60 min/g. In contrast, 1 microM polyglutamic acid (poly-glun; and anionic peptide) did not affect the clearance of FITC-dx 150 (605 nl/60 min/g). At 0.5 and 1.0 nM, poly-argn increased the clearance of FITC-dx 150 from 610 to 1722 and 2396 nl/60 min/g (P < 0.05). Similarly, 0.5 nM MaBP increased clearance from 591 +/- 38 to 1967 +/- 168 nl/60 min/g. L-NAME at 10(-4) M did not prevent the 0.5 nM MaBP-induced elevation in clearance (1784 +/- 350). Poly-argn at 1 nM increased net mean IOI by 21.5 +/- 7.2 units. This elevation was not inhibited by topical 10(-4) M L-NMMA (27.5 +/- 8.4). Using 0.5 nM poly-argn as agonist, we assayed suffusate samples for their histamine concentration using a competitive enzyme immunoassay and found no detectable histamine. Pyrilamine, an H1 antagonist, did not inhibit the 0.5 nM poly-argn-induced elevation in clearance of FITC-dx 150. We conclude that (1) cationic peptides and MaBP increase microvascular permeability and (2) the increase in microvascular permeability produced by low concentrations of poly-argn and by MaBP is independent of the release of histamine and does not require nitric oxide.