Bioassay guided purification of the antimicrobial fraction of a Brazilian propolis from Bahia state

Background  

Brazilian propolis type 6 (Atlantic forest, Bahia) is distinct from the other types of propolis especially due to absence of flavonoids and presence of other non-polar, long chain compounds, but presenting good in vitro and in vivo antimicrobial activity. Several authors have suggested that fatty acids found in this propolis might be responsible for its antimicrobial activity; however, so far no evidence concerning this finding has been reported in the literature. The goals of this study were to evaluate the antibacterial activity of the main pure fatty acids in the ethanolic extract and fractions and elucidate the chemical nature of the bioactive compounds isolated from Brazilian propolis type 6.     

Passive mechanical properties of cardiac tissues in heart hypertrophy during pregnancy

We evaluated changes in passive mechanical properties in cardiac tissues during rat pregnancy. Left and right ventricular free walls were dissected from hearts of nonpregnant, late-pregnant, and postpartum rats. Mechanical experiments in ventricular strips were done by stretch–release cycles using a step motor. The results show that during pregnancy, there is cardiac hypertrophy associated with (1) an increase in myocyte size, particularly of augmented myocyte length, (2) a decrease in passive tension developed by the myocardial walls, and (3) a decrease in both elastic modulus and hysteresis. All changes observed during rat pregnancy were reversed during postpartum. In conclusion, a heart with less ventricular rigidity could contribute to facilitating the ventricular filling in conditions of a greater circulating volume characteristic of pregnancy. J. L. Marin deceased: 16 November 2007.     

Childhood radiation‐associated atypical meningioma with novel complex rearrangements involving chromosomes 1 and 12

Meningiomas are recognized as the most common late complication following radiotherapy. However, cytogenetic studies in childhood atypical radiation‐induced meningioma are sporadic, mainly because this condition generally occurs after a long latent period. In the present study we show the results of conventional and molecular cytogenetics in a 14‐year‐old boy with a secondary atypical meningioma. Apart from numerical changes, we found complex aberrations with the participation of chromosomes 1, 6 and 12. The invariable presence of loss of 1p was demonstrated by fluorescent in situ hybridization (FISH) analysis with probes directed to telomeric regions and by comparative genome hybridization (CGH). Previous cytogenetic studies on adult spontaneous and radiation‐associated meningiomas showed loss of chromosome 22 as the most frequent change, followed by loss of the short arm of chromosome 1. To the best of our knowledge this is the first report of highly complex chromosome aberrations in the pediatric setting of meningioma.     

Phenotypic alterations of neurons that innervate osteoarthritic joints in rats

Objective

Pain is a prominent feature of osteoarthritis (OA). To further understand the primary mechanisms of nociception in OA, we studied the expression of the phenotype markers calcitonin gene‐related peptide (CGRP), isolectin B4 (IB4), and neurofilament 200 (NF200) in sensory neurons innervating the OA knee joint in rats.

Methods

OA was induced in rats by intraarticular injection of 2 mg of mono‐iodoacetate (MIA) into the knee. Neurons innervating the joint were identified by retrograde labeling with fluorogold in dorsal root ganglia (DRG) and colocalized with neurochemical markers by immunofluorescence. The total number of DRG cells was determined by stereologic methods in Nissl‐stained sections.

Results

A 37% decrease in the number of fluorogold‐backlabeled cells was observed in rats with OA when compared with control rats, even though no decrease in the total number of cells was observed. However, an increase in the number of medium/large cell bodies and a decrease in the number of the smallest cells were observed, suggesting the occurrence of perikarya hypertrophy. The percentage of CGRP‐positive cells increased significantly, predominantly in medium/large cells, suggesting the occurrence of a phenotypic switch. Colocalization of CGRP and NF200 revealed no significant changes in the percentage of double‐labeled cells, but an increase in the number of medium/large double‐labeled cells was observed. No differences in the expression of either IB4 or NF200 were observed in fluorogold‐backlabeled cells.

Conclusion

These results indicate that MIA‐induced OA causes an up‐regulation of CGRP in different subpopulations of primary afferent neurons in DRG due to a phenotypic switch and/or cell hypertrophy which may be functionally relevant in terms of the onset of pain in this pathologic condition.

     

Connexin36, an essential element in the rod pathway,is highly expressed in the essentially rodless retina of Gallus gallus

Electrical coupling provided by connexins (Cx) in gap junctions (GJ) plays important roles in both the developing and the mature retina. In mammalian nocturnal species, Cx36 is an essential component in the rod pathway, the retinal circuit specialized for night, scotopic vision. Here, we report the expression of Cx36 in a species (Gallus gallus) that phylogenetic development endows with an essentially rodless retina. Cx36 gene is very highly expressed in comparison with other Cxs previously described in the adult retina, such as Cx43, Cx45, and Cx50. Moreover, real‐time PCR, Western blot, and immunofluorescence all revealed that Cx36 expression massively increased over time during development. We thoroughly examined Cx36 in the inner and outer plexiform layers, where this protein was particularly abundant. Cx36 was observed mainly in the off sublamina of the inner plexiform layer rather than in the on sublamina previously described in the mammalian retina. In addition, Cx36 colocalized with specific cell markers, revealing the expression of this protein in distinct amacrine cells. To investigate further the involvement of Cx36 in visual processing, we examined its functional regulation in retinas from dark‐adapted animals. Light deprivation markedly up‐regulates Cx36 gene expression in the retina, resulting in an increased accumulation of the protein within and between cone synaptic terminals. In summary, the developmental regulation of Cx36 expression results in particular circuitry‐related roles in the chick retina. Moreover, this study demonstrated that Cx36 onto‐ and phylogenesis in the vertebrate retina simultaneously exhibit similarities and particularities. J. Comp. Neurol. 512:651–663, 2009. © 2008 Wiley‐Liss, Inc.     

Effect of weight loss after weight loss surgery on plasma N-terminal pro-B-type natriuretic peptide levels

Natriuretic peptides have multiple beneficial cardiovascular effects. Previous cross-sectional studies have indicated that obese subjects have lower natriuretic peptide concentrations than those of normal weight. It is not known whether this relative natriuretic peptide deficiency is reversible with weight loss. We studied 132 obese subjects undergoing weight loss surgery with serial measurement of plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentrations at preoperative, early (1 to 2 months), and late postoperative (6 months) points. In addition, 20 subjects also underwent echocardiography at baseline and 6 months after surgery. Significant weight loss was observed after surgery (median body mass index 45.1, 41.0, and 32.9 kg/m(2) for the 3 corresponding points, analysis of variance p <0.001). The median NT-proBNP levels increased substantially (31.6, 66.9, and 84.9 pg/ml; p <0.001). The average intrasubject increase in NT-proBNP at the 2 postoperative points was 3.4 and 5.0 times the preoperative level (p <0.001 for both points vs preoperatively). In the multivariate regression models adjusted for clinical characteristics and insulin resistance, the strongest predictor of the change in NT-proBNP level 6 months after weight loss surgery was the change in weight (p = 0.03). Echocardiography showed a mean intrasubject reduction in left ventricular mass index of 18% (p <0.001) and mild improvements in diastolic function, with no change in ejection fraction. In conclusion, we have demonstrated that weight loss is associated with early and sustained increases in NT-proBNP concentrations, despite evidence of preserved systolic and improved diastolic function. These findings suggest a direct, reversible relation between obesity and reduced natriuretic peptide levels.     

Inappropriate serum levels of retinol, alpha-tocopherol, 25 hydroxyvitamin D3 and 24,25 dihydroxyvitamin D3 levels in healthy Spanish adults: simultaneous assessment by HPLC

Objective

Simultaneous assessment of the status of lipid-soluble vitamins; retinol, α-tocopherol, 25 hydroxyvitamin D₃ and 24,25 dihydroxyvitamin D₃ in serum of blood donors, paradigm of a healthy population.

Patients and methods

Serum samples were supplied by the Regional Blood Donors Center in Cordoba from 215 healthy Spanish individuals (166 males and 99 females). Target analytes were determined using liquid-liquid extraction and separation-detection by HPLC.

Results

The method was validated using standard reference material (SRM 968c, NIST). Standard errors were 1.4%, 2.1% and 1.8% for 25OHD₃, vitamin A and vitamin E, respectively.The ranges thus assessed were as follows: 17.1 ± 8.0 nmol/L, for 24,25(OH)₂D₃, 40.3 ± 34.6 nmol/L for 25OHD₃, 2.57 ± 0.7 μmol/L for retinol and 22.13 ± 8.30 μmol/L for α-tocopherol. Females showed lower serum levels of retinol (p < 0.01), α-tocopherol (p < 0.01) and 25OHD₃ (p = 0.028).A total of 10.4% subjects showed vitamin E deficiency, 85.4% had normal levels and 4.2% had high levels of vitamin E. 65.6% of the target subjects showed normal levels of retinol, and 1.6% had moderate or severe vitamin A deficiency. High levels of vitamin A were found in 32.8% of the subjects.Fourteen percent of the healthy subjects showed severe vitamin D deficiency (serum levels of 25OHD₃ < 25 nmol/L), 50.8% had vitamin D₃ insufficiency (25OHD₃ from 25 to 50 nmol/L), 17.6% of the subjects had suboptimal 25OHD₃ serum levels (25OHD₃ from 50 to 75 nmol/L), only 16.8% had an adequate status of 25OHD₃ and 0.8% had high levels of vitamin D (25OHD₃ > 200 nmol/L). Among subjects with vitamin D below 50 nmol/L, 49.38% had high levels of retinol (over 2.4 μmol/L). This association is considered a risk factor for osteoporosis and fracture.

Conclusions

The reported data of high prevalence of lipid-soluble vitamin values outside the physiological range have important repercussions on public health. These data also uphold the need for simultaneous measurement of fat-soluble vitamins as a valuable tool in clinical practice as well as in epidemiological studies for awareness and correction.     

Low level and sub-chronic exposure to methylmercury induces hypertension in rats: nitric oxide depletion and oxidative damage as possible mechanisms

Increased risk of hypertension after methylmercury (MeHg) exposure has been suggested. However, the underlying mechanisms are not well explored. In this paper, we have analyzed whether sub-chronic exposure to MeHg increases systolic blood pressure even at very low levels. In addition, we analyzed if the methylmercury-induced hypertension is associated with a decreased plasmatic nitric oxide levels and with a dysregulation of the activities of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT), as well as the levels of MDA and glutathione. For this study, Wistar rats were treated with methylmercury chloride (100 μg/kg per day) or vehicle. Total treatment time was 100 days. Malondialdehyde (MDA) and circulating NOx levels and superoxide dismutase (SOD) and catalase (CAT) activities were determined in plasma, whereas glutathione levels were determined in erythrocytes. Our results show that long-term treatment at a low level of MeHg affected systolic blood pressure, increasing and reducing the levels of plasmatic MDA and NOx, respectively. However, the activity of SOD did not decrease in the MeHg exposed group when compared to the control. We found a negative correlation between plasmatic nitrite/nitrate (NOx) levels and systolic blood pressure (r = −0.67; P = 0.001), and a positive correlation between MDA and systolic blood pressure (r = 0.61; P = 0.03), thus suggesting increased inhibition of NO formation with the increase of hypertension. In conclusion, long-term exposure to a low dose of MeHg increases the systolic pressure and is associated, at least in part, with increased production of ROS as judged by increased production of malondialdehyde and depressed NO availability.